Data Modeling, Development, Installation and Operation of the ACEX Offshore Drilling Information System for the Mission Specific Platform Expedition to the Lomonosov Ridge, Arctic Ocean.

NASA Astrophysics Data System (ADS)

Conze, R.; Krysiak, F.; Wallrabe-Adams, H.; Graham, C. C.

2004-12-01

During August/September 2004, the Arctic Coring Expedition (ACEX) was used to trial a new Offshore Drilling Information System (OffshoreDIS). ACEX was the first Mission Specific Platform (MSP) expedition of the Integrated Ocean Drilling Programme (IODP), funded by the European Consortium for Ocean Research Drilling (ECORD). The British Geological Survey in conjunction with the University of Bremen and the European Petrophysics Consortium were the ECORD Science Operator (ESO) for ACEX. IODP MSP expeditions have very similar data management requirements and operate in similar working environments to the lake drilling projects conducted by the International Continental Scientific Drilling Program (ICDP), for example, the GLAD800, which has very restricted space on board and operates in difficult conditions. Both organizations require data capture and management systems that are mobile, flexible and that can be deployed quickly on small- to medium-sized drilling platforms for the initial gathering of data, and that can also be deployed onshore in laboratories where the bulk of the scientific work is conducted. ESO, therefore, decided that an adapted version of the existing Drilling Information System (DIS) used by ICDP projects would satisfy its requirements. Based on the existing DIS, an OffshoreDIS has been developed for MSP expeditions. The underlying data model is compatible with IODP(JANUS), the Bremen Core Repository, WDC-MARE/PANGAEA and the LacCore in Minneapolis. According to the specific expedition platform configuration and on-board workflow requirements for the Arctic, this data model, data pumps and user interfaces were adapted for the ACEX-OffshoreDIS. On the drill ship Vidar Viking the cores were catalogued and petrophysically logged using a GeoTek Multi-Sensor Core Logger System, while further initial measurements, lithological descriptions and biostratigraphic investigations were undertaken on the Oden, which provided laboratory facilities for the expedition. Onboard samples were registered in a corresponding sample archive on both vessels. The ACEX-OffshoreDIS used a local area network covering the two ships of the three icebreaker fleet by wireless LAN between the ships and partly wired LAN on the ships. A DIS-server was installed on each ship. These were synchronized by database replication and linked to a total of 10 client systems and label printers across both ships. The ACEX-OffshoreDIS will also be used for the scientific measurement and analysis phase of the expedition during the post-field operations `shore-party' in November 2004 at the Bremen Core Repository (BCR). The data management system employed in the Arctic will be reconfigured and deployed at the BCR. In addition, an eXtended DIS (XDIS) Web interface will be available. This will allow controlled sample distribution (core curation, sub-sampling) as well as sharing of data (registration, upload and download) with other laboratories which will be undertaking additional sampling and analyses. The OffshoreDIS data management system will be of long-term benefit to both IODP and ICDP, being deployed in forthcoming MSP offshore projects, ICDP lake projects and joint IODP-ICDP projects such as the New Jersey Coastal Plain Drilling Project.

South China Sea Tectonics and Magnetics: Constraints from IODP Expedition 349 and Deep-tow Magnetic Surveys

NASA Astrophysics Data System (ADS)

Lin, J.; Li, C. F.; Kulhanek, D. K.; Zhao, X.; Liu, Q.; Xu, X.; Sun, Z.; Zhu, J.

2014-12-01

The South China Sea (SCS) is the largest low-latitude marginal sea in the world. Its formation and evolution are linked to the complex continental-oceanic tectonic interaction of the Eurasian, Pacific, and Indo-Australian plates. Despite its relatively small size and short history, the SCS has undergone nearly a complete Wilson cycle from continental break-up to seafloor spreading to subduction. In January-March 2014, Expedition 349 of the International Ocean Discovery Program (IODP) drilled five sites in the deep basin of the SCS. Three sites (U1431, U1433, and U1434) cored into oceanic basement near the fossil spreading center on the East and Southwest Subbasins, whereas Sites U1432 and U1435 are located near the northern continent/ocean boundary of the East Subbasin. Shipboard biostratigraphy based on microfossils preserved in sediment directly above or within basement suggests that the preliminary cessation age of spreading in both the East and Southwest Subbasins is around early Miocene (16-20 Ma); however, post-cruise radiometric dating is being conducted to directly date the basement basalt in these subbasins. Prior to the IODP drilling, high-resolution near-seafloor magnetic surveys were conducted in 2012 and 2013 in the SCS with survey lines passing near the five IODP drilling sites. The deep-tow surveys revealed detailed patterns of the SCS magnetic anomalies with amplitude and spatial resolutions several times better than that of traditional sea surface measurements. Preliminary results reveal several episodes of magnetic reversal events that were not recognized by sea surface measurements. Together the IODP drilling and deep-tow magnetic surveys provide critical constraints for investigating the processes of seafloor spreading in the SCS and evolution of a mid-ocean ridge from active spreading to termination.

Education and Outreach from the JOIDES Resolution during IODP Expedition 360 : linking onboard research and classroom activities during and after the Expedition.

NASA Astrophysics Data System (ADS)

Burgio, M.; Zhang, J.; Kavanagh, L.; Martinez, A. O.; Expedition 360 Scientists, I.

2016-12-01

The International Ocean Discovery Program (IODP) expeditions provide an excellent opportunity for onboard Education Officers (EO) to communicate and disseminate exciting shipboard research and discoveries to students around the world. During expedition 360, the EOs carried out 140 live webcasts, using different strategies to create an effective link between both students and scientists. Below are examples of strategies we used: -Primary school: The Beauty of Gabbro! and Life in the rocks! During the webcasts, students could virtually tour the ship, interview scientists, and see and discuss samples of the cored gabbro and minerals in thin sections. Artistic contextualization by J. Zhang, facilitated these activities. Moreover, highlighting the search for microbes in the Earth's crust , was particularly successful in engaging the students. -Middle and High school: Fun and relationships in science. Students were able to email expert scientists in the scientific discipline they chose to research and interview them during a live webcast. Some students created a song about the expedition. "on the boat - cup song - IODP project" https://www.youtube.com/watch?v=qex-w9aSV7c-University: Travels, research and the everyday life of professors onboard. We used webcasts to connect with universities in France, Japan and Italy, to create vibrant interactions between students and scientists that enabled students to get closer to their professors and understand better the life of onboard researchers. In collaboration with the science party we developed new strategies to keep in touch with students after completion of the cruise. We generated teaching kits consisting of pedaqgoical sets of pictures, exercises using onboard data, a continuously updated map "tracking geologists", and live webcasts to be organized from laboratories to schools. We already have had enthusiastic feedback from teachers that took part in our webcasts and the challenge is to continue to foster the relationships we created.

Using DSDP/ODP/IODP core photographs and digital images in the classroom

NASA Astrophysics Data System (ADS)

Pereira, Hélder; Berenguer, Jean-Luc

2017-04-01

Since the late 1960's, several scientific ocean drilling programmes have been uncovering the history of the Earth hidden beneath the seafloor. The adventure began in 1968 with the Deep Sea Drilling Project (DSDP) and its special drill ship, the Glomar Challenger. The next stage was the Ocean Drilling Program (ODP) launched in 1985 with a new drill ship, the JOIDES Resolution. The exploration of the ocean seafloor continued, between 2003 and 2013, through the Integrated Ocean Drilling Program (IODP). During that time, in addition to the JOIDES Resolution, operated by the US, the scientists had at their service the Chikyu, operated by Japan, and Mission-Specific-Platforms, funded and implemented by the European Consortium for Ocean Research Drilling. Currently, scientific ocean drilling continues through the collaboration of scientists from 25 nations within the International Ocean Discovery Program (IODP). Over the last 50 years, the scientific ocean drilling expeditions conducted by these programmes have drilled and cored more than 3500 holes. The numerous sediment and rock samples recovered from the ocean floor have provided important insight on the active biological, chemical, and geological processes that have shaped the Earth over millions of years. During an expedition, once the 9.5-meter long cores arrive from the seafloor, the technicians label and cut them into 1.5-meter sections. Next, the shipboard scientists perform several analysis using non-destructive methods. Afterward, the technicians split the cores into two halves, the "working half", which scientists sample and use aboard the drilling platform, and the "archive half", which is kept in untouched condition after being visually described and photographed with a digital imaging system. The shipboard photographer also takes several close-up pictures of the archive-half core sections. This work presents some examples of how teachers can use DSDP/ODP/IODP core photographs and digital images, available through the Janus and LIMS online databases, to develop inquiry-based learning activities for secondary level students.

Hundreds of Cruises, Thousands of People, Endless Discoveries - Education and Outreach in the Integrated Ocean Drilling Program

NASA Astrophysics Data System (ADS)

Peart, L.; Niemitz, M.; Boa, S.; Corsiglia, J.; Klaus, A.; Petronotis, K.; Iturrino, G.

2005-12-01

For 37 years, scientific ocean drilling programs have sponsored hundreds of expeditions, drilled at over 1,800 sites and recovered over 200 miles of core. The discoveries of these programs have led to important realizations of how our earth works. Past expeditions have validated the theory of plate tectonics, provided unparalleled ancient climate records and recovered evidence of the asteroid impact that wiped out the dinosaurs 65 million years ago - and new discoveries occur with every expedition. By producing education materials and programs and encouraging mass media journalists' interest in our news, we strive to fulfill our commitment to communicate our programs' scientific discoveries to the public, in a way that people - not just other scientists - understand. With the advent of the Integrated Ocean Drilling Program (IODP), education and outreach efforts have expanded to pursue new opportunities and engage wider audiences. Through our strategy of Teaching for Science, Learning for LifeTM, our education efforts seek to utilize the interdisciplinary nature of scientific ocean drilling to teach career awareness, scientific methods, teamwork, and problem solving techniques for a lifetime of learning, decision making and good citizenship. In pursuit of this goal, we have implemented professional and resource development programs and expanded our outreach at education-focused conferences to help teachers use IODP science to satiate the student's need to learn the methods of science that apply to everyday life. We believe that this message also applies to life-long learners and thus we have focused our efforts on news media outreach and education opportunities surrounding ports of call of the JOIDES Resolution, permanent and traveling museum exhibits. In addition, our outreach to undergraduate and graduate audiences, through a lecture series, research fellowships and internships, helps to create future generations of science leaders.

A comparison of petrophysical data inputs for establishing time-depth relationships: a guide for future drilling expeditions

NASA Astrophysics Data System (ADS)

Boaga, J.; Sauermilch, I.; Mateo, Z. R. P.

2017-12-01

Time-depth relationships (TDR) are crucial in correlating drillhole and core information to seismic reflection profiles, for accurate resource estimation, scientific interpretation and to guide drilling operations. Conventional seismic time-depth domain conversion utilizes downhole sonic logs (DSI), calibrated using available checkshot data, which are local travel times from the surface to a particular depth. Scientific drilling programs (ODP and IODP) also measure P-wave velocity (PWL or C) on recovered core samples. Only three percent of all ODP and IODP sites record all three velocity measurements, however this information can be instructive as sometimes these data input show dissimilar TDR. These representative sites provide us with an opportunity to perform a comparative analysis highlighting the differences and similarities of TDRs derived from checkshot, downhole, and laboratory measurements. We then discuss the impact of lithology, stratigraphy, water column and other petrophysical properties in the predictive accuracy of TDR calculations, in an effort to provide guidance for future drilling and coring expeditions.

Virtual special issue on IODP Expedition 339: The Mediterranean outflow

NASA Astrophysics Data System (ADS)

Hodell, D. A.; Hernández-Molina, F. Javier; Stow, Dorrik A. V.; Alvarez-Zarikian, Carlos

2016-09-01

IODP Expedition 339 had two inter-related objectives to recover continuous sedimentary sequences for: (i) studying the Contourite Depositional System formed by the MOW; and (ii) reconstructing North Atlantic climate variability on orbital and suborbital time scales. This Elsevier Virtual Special Issue (VSI) ;Mediterranean Outflow; is comprised of two volumes that are roughly divided along these lines with Marine Geology devoted to (i) and Global and Planetary Change to (ii), although some papers overlap the two themes. The Marine Geology volume contains 9 contributions addressing specific aspects of IODP Expedition 339 related to contourite deposits including sedimentology, seismic interpretation, stratigraphy, physical properties, downhole logging and ichnofacies (Hernández-Molina et al., 2015; Lofi et al., 2015; Ducassou et al., 2015; Alonso et al., 2015; Takashimizu et al., 2016; Nishida, 2015; Dorador and Rodríguez-Tovar, 2015a, 2015b; Kaboth et al., 2015). The Global and Planetary Change volume consists of 18 papers described below, highlighting paleoclimatic results from sites drilled on the SW Iberian Margin and in the Gulf of Cadiz. The two volumes provide a sample of emerging results of Expedition 339 and foretell of the promising research yet to come.

Characterizing structures on borehole images and logging data of the Nankai trough accretionary prism: new insights

NASA Astrophysics Data System (ADS)

Jurado, Maria Jose

2016-04-01

IODP has extensively used the D/V Chikyu to drill the Kumano portion of the Nankai Trough, including two well sites within the Kumano Basin. IODP Expeditions 338 and 348 drilled deep into the inner accretionary prism south of the Kii Peninsula collecting a suite of LWD data, including natural gamma ray, electrical resistivity logs and borehole images, suitable to characterize structures (fractures and faults) inside the accretionary prism. Structural interpretation and analysis of logging-while-drilling data in the deep inner prism revealed intense deformation of a generally homogenous lithology characterized by bedding that dips steeply (60-90°) to the NW, intersected by faults and fractures. Multiple phases of deformation are characterized. IODP Expedition borehole images and LWD data acquired in the last decade in previous and results of NantroSEIZE IODP Expeditions (314, 319) were also analyzed to investigate the internal geometries and structures of the Nankai Trough accretionary prism. This study focused mainly on the characterization of the different types of structures and their specific position within the accretionary prism structures. New structural constraints and methodologies as well as a new approach to the characterization of study of active structures inside the prism will be presented.

Examination of the Asian Monsoon: Ongoing Studies from IODP Expedition 346

NASA Astrophysics Data System (ADS)

Murray, R. W.; Tada, R.; Alvarez Zarikian, C. A.

2014-12-01

IODP Expedition 346 (Asian Monsoon) tested the hypothesis that Plio-Pleistocene uplift of the Himalaya and Tibetan Plateau, and/or emergence and growth of the northern hemisphere ice sheets and establishment of the two discrete modes of Westerly Jet circulation, is the cause of the millennial-scale variability of the East Asian summer monsoon (EASM) and amplification of Dansgaard-Oeschger cycles. We also examined whether the nature and strength of flow through the Tsushima Strait (which is strongly affected by EASM precipitation, sea level changes, and EAWM cooling) influenced surface and deepwater conditions of the Japan, Yamato, and Ulleung Basins. During only six weeks of drilling, Expedition 346 recovered 6135.3 m of core, which established an IODP record for the amount of recovered material. Because of recent advances in drilling technology and newly developed analytical tools, we were able to examine records that were impossible to acquire even a few years ago. The newly engineered half piston core system recovered the deepest piston core in DSDP/ODP/IODP history (490.4 m in Hole U1427A), which was reached by continuous piston coring from the seafloor. These advances delivered new surprises. We recovered pristine dark-light laminae from approximately 8 Ma sediment from 275 m below the seafloor at Site U1425 (Yamato Rise) and from 210 m below the seafloor (10-12 Ma) at Site U1430 in the Ulleung Basin. Aggressive sampling for geochemistry provided important constraints on the diagenetic and chemical environments throughout these marginal seas, and yet did not negatively compromise paleoceanographic objectives. We are extending earlier pioneering results of the Quaternary dark and light layers in these basins and which record variations of EASM precipitation over South China. Drilling in the East China Sea is providing an excellent record of EASM precipitation because its surface water salinity and temperature during summer is significantly influenced by Yangtze River discharge. Ash records are providing calibrated stratigraphic control and improving understanding of arc history. Interpreting these and other results in the context of other IODP drilling expeditions, such as Expedition 349 to the South China Sea, will be critical to develop a holistic understanding of the Asian monsoon system.

International Collaboration in Data Management for Scientific Ocean Drilling: Preserving Legacy Data While Implementing New Requirements.

NASA Astrophysics Data System (ADS)

Rack, F. R.

2005-12-01

The Integrated Ocean Drilling Program (IODP: 2003-2013 initial phase) is the successor to the Deep Sea Drilling Project (DSDP: 1968-1983) and the Ocean Drilling Program (ODP: 1985-2003). These earlier scientific drilling programs amassed collections of sediment and rock cores (over 300 kilometers stored in four repositories) and data organized in distributed databases and in print or electronic publications. International members of the IODP have established, through memoranda, the right to have access to: (1) all data, samples, scientific and technical results, all engineering plans, data or other information produced under contract to the program; and, (2) all data from geophysical and other site surveys performed in support of the program which are used for drilling planning. The challenge that faces the individual platform operators and management of IODP is to find the right balance and appropriate synergies among the needs, expectations and requirements of stakeholders. The evolving model for IODP database services consists of the management and integration of data collected onboard the various IODP platforms (including downhole logging and syn-cruise site survey information), legacy data from DSDP and ODP, data derived from post-cruise research and publications, and other IODP-relevant information types, to form a common, program-wide IODP information system (e.g., IODP Portal) which will be accessible to both researchers and the public. The JANUS relational database of ODP was introduced in 1997 and the bulk of ODP shipboard data has been migrated into this system, which is comprised of a relational data model consisting of over 450 tables. The JANUS database includes paleontological, lithostratigraphic, chemical, physical, sedimentological, and geophysical data from a global distribution of sites. For ODP Legs 100 through 210, and including IODP Expeditions 301 through 308, JANUS has been used to store data from 233,835 meters of core recovered, which are comprised of 38,039 cores, with 202,281 core sections stored in repositories, which have resulted in the taking of 2,299,180 samples for scientists and other users (http://iodp.tamu.edu/janusweb/general/dbtable.cgi). JANUS and other IODP databases are viewed as components of an evolving distributed network of databases, supported by metadata catalogs and middleware with XML workflows, that are intended to provide access to DSDP/ODP/IODP cores and sample-based data as well as other distributed geoscience data collections (e.g., CHRONOS, PetDB, SedDB). These data resources can be explored through the use of emerging data visualization environments, such as GeoWall, CoreWall (http://(www.evl.uic.edu/cavern/corewall), a multi-screen display for viewing cores and related data, GeoWall-2 and LambdaVision, a very-high resolution, networked environment for data exploration and visualization, and others. The U.S Implementing Organization (USIO) for the IODP, also known as the JOI Alliance, is a partnership between Joint Oceanographic Institutions (JOI), Texas A&M University, and Lamont-Doherty Earth Observatory of Columbia University. JOI is a consortium of 20 premier oceanographic research institutions that serves the U.S. scientific community by leading large-scale, global research programs in scientific ocean drilling and ocean observing. For more than 25 years, JOI has helped facilitate discovery and advance global understanding of the Earth and its oceans through excellence in program management.

NanTroSEIZE in 3-D: Creating a Virtual Research Experience in Undergraduate Geoscience Courses

NASA Astrophysics Data System (ADS)

Reed, D. L.; Bangs, N. L.; Moore, G. F.; Tobin, H.

2009-12-01

Marine research programs, both large and small, have increasingly added a web-based component to facilitate outreach to K-12 and the public, in general. These efforts have included, among other activities, information-rich websites, ship-to-shore communication with scientists during expeditions, blogs at sea, clips on YouTube, and information about daily shipboard activities. Our objective was to leverage a portion of the vast collection of data acquired through the NSF-MARGINS program to create a learning tool with a long lifespan for use in undergraduate geoscience courses. We have developed a web-based virtual expedition, NanTroSEIZE in 3-D, based on a seismic survey associated with the NanTroSEIZE program of NSF-MARGINS and IODP to study the properties of the plate boundary fault system in the upper limit of the seismogenic zone off Japan. The virtual voyage can be used in undergraduate classes at anytime, since it is not directly tied to the finite duration of a specific seagoing project. The website combines text, graphics, audio and video to place learning in an experiential framework as students participate on the expedition and carry out research. Students learn about the scientific background of the program, especially the critical role of international collaboration, and meet the chief scientists before joining the sea-going expedition. Students are presented with the principles of 3-D seismic imaging, data processing and interpretation while mapping and identifying the active faults that were the likely sources of devastating earthquakes and tsunamis in Japan in 1944 and 1948. They also learn about IODP drilling that began in 2007 and will extend through much of the next decade. The website is being tested in undergraduate classes in fall 2009 and will be distributed through the NSF-MARGINS website (http://www.nsf-margins.org/) and the MARGINS Mini-lesson section of the Science Education Resource Center (SERC) (http://serc.carleton.edu/margins/collection.html) in early 2010.

Geochemistry of basement rocks of incoming plate (Cocos Ridge) from Sites U1381 and 1414, IODP Expeditions 334 and 344

NASA Astrophysics Data System (ADS)

Yan, Q.; Shi, X.

2015-12-01

The drilling sites of IODP 334 and 344 lie in the being subducted part of Cocos Ridge, offshore Costa Rica. Some seamount clusters distributed in the northwest side of the sites. Most scientists accepted that the Cocos ridge is intimately related to the activity of Galapagos plume (e.g., Hoernle et al., 2000, 2004, 2008). In this study we have selected some basaltic samples from U1381A, U1381C and U1414A (IODP 334 and 344) (Harris et al., 2015a, b) to carry out petrogenetic study. Major element compositions show that these basaltic rocks belong to sub-alkaline rocks, which is consistent with previous study on basalts from northern side of Cocos ridge. The characteristics of trace element composition are similar to that of EMORB, and the compositional differences in trace elements among samples reflect the influence of fractional crystallization. Sr-Nd-Pb isotopic compositions of these basaltic rocks show that there exist mantle heterogeneity beneath the Cocos ridge, and they may be the product of mixing between DMM/GSC and EMII. The new data show more enriched source feature than those from Galapagos hotspot (and its tracks) in previous study (Hoernle et al., 2000,2004), and slightly more enriched than those Miocene to Pliocene arc volcanics from Central America (Gazel et al., 2009). Partial melting model show that the parental basalts for these basaltic rocks may be produced by 13 to 28% partial melting of garnet pyroxenite. ReferencesGazel et al., 2009. G-cubed.10, Q02S11, doi:10.1029/2008GC002246.//Harris, R.N., Sakaguchi, A., Petronotis, K., and the Expedition 344 Scientists. 2015a. Input Site U1381. Proceedings of the Integrated Ocean Drilling Program, Volume 344//Harris, R.N., Sakaguchi, A., Petronotis, K., and the Expedition 344 Scientists. 2015b. Input Site U1414.Proceedings of the Integrated Ocean Drilling Program, Volume 344//Hoernle et al., 2000. Geology, 28(5),435-438//Hoernle et al., 2004. Geology, 32,697-700//Hoernle et al., 2008. Nature, 451,1094-1098 (This study was supported by National Natural Science Foundation of China (NSFC nos. 41296030 and 41322036, and IODP-China.)

Regional distribution of volcaniclastic layer and its implication for segmentation of the Nankai seismogenic zone

NASA Astrophysics Data System (ADS)

Sasaki, T.; Lim, J.; Higashi, M.; Park, J.

2010-12-01

The Nankai Trough is known as one of the best-suited convergent plate margins for studying accretionary prism growth as well as subduction zone earthquakes. Along the Nankai accretionary margin off southwest Japan, the Shikoku Basin which formed 26-15 Ma as backarc spreading in the Philippine Sea Plate is being subducted about 4 cm/year to the northwest. The Deep Sea Drilling Project (DSDP) and Ocean Drilling Program (ODP) penetrated the Nankai accretionary prism and the incoming sedimentary section along the Ashizuri and Muroto transects, off Shikoku Island. Also, Integrated Ocean Drilling Program (IODP), which represented just one part of a multi-stage project known as the Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) has been conducting drilling cruises now. IODP Expedition 322 in 2009, the coring was carried out at two drilling sites on the northern part of the Shikoku Basin in the subducting Philippine Sea plate. One of the major achievements of Expedition 322 is a discovery of late Miocene (10.2-7.6 Ma) tuffaceous and volcaniclastic sandstone layer (Underwood et al., IODP Prel. Rept. 322, 2009) that has not been previously recognized in the Nankai Trough. Based on age and volcanic sand content analysis, these volcaniclastic layers were unique to the Shikoku Basin off Kii Peninsula. The closest source of this volcanic layer was supposed to be the Izu-Bonin arc. Subducted sediments ultimately affect subduction zone geochemistry, thermal structure, and seismogenesis. High porosity of the volcaniclastic sandstone layer suggests the transportation of fluid to the subduction zone, it might affect the initiation and evolution of the decollement zone or plate boundary fault in the Nankai Trough. We interpreted single channel and multichannel seismic reflection profiles that have been acquired in the Nankai Trough margin by Japan Agency for Marine-Earth Science and Technology (JAMSTEC) since the year of 1997. We tried to map the major seismic layers such as volcaniclastic layer, volcanic ash layer and turbidite layers which were found at drilling sites in the IODP Expedition 322 in the northern Shikoku Basin. As a result, we recognized that these prominent seismic layers are widely distributed in the northern Shikoku Basin. In this talk, we will show specific seismic layers directly connecting to the decollement at the Nankai Trough axis, and discuss its implications for subduction processes in the Nankai Trough margin.

New scientific ocean drilling depth record extends study of subseafloor life

NASA Astrophysics Data System (ADS)

Showstack, Randy

2012-09-01

The Japanese deep-sea drilling vessel Chikyu set a new depth record for scientific ocean drilling and core retrieval by reaching a depth of 2119.5 meters below the seafloor (mbsf) on 6 September. This is 8.5 meters deeper than the prior record, set 19 years ago. Three days later, on 9 September, Chikyu set another record by reaching a drilling depth of 2466 mbsf, the maximum depth that will be attempted during the current expedition. The 6 September record was set on day 44 of the Deep Coalbed Biosphere off Shimokita expedition, which is expedition 337 of the Integrated Ocean Drilling Program (IODP). It occurred at drilling site C0020 in the northwestern Pacific Ocean, approximately 80 kilometers northeast from Hachinohe, Japan. The expedition is scheduled to conclude on 30 September.

Metabolic Activity and Biosignatures of Microbes in the Lower Ocean Crust of Atlantis Bank, IODP Expedition 360

NASA Astrophysics Data System (ADS)

Wee, S. Y.; Edgcomb, V. P.; Burgaud, G.; Klein, F.; Schubotz, F.; Yvon-Lewis, S. A.; Sylvan, J. B.

2017-12-01

International Ocean Discovery Program (IODP) Expedition 360 represents the first leg of a multi-phase drilling program, SloMo, aimed at investigating the nature of the lower crust and Moho at slow spreading ridges. The goal of Expedition 360 was to recover a representative transect of the lower oceanic crust formed at Atlantis Bank, an oceanic core complex on the SW Indian Ridge. Recovered cores were primarily gabbro and olivine gabbro, which may potentially host serpentinization reactions and associated microbial life. Our goal was to sample this subseafloor environment and determine quantity, diversity and metabolic capabilities of any resident microbial life. Hole U1473A was drilled during Expedition 360 down to 790 m below seafloor and samples for detection of microbial communities and microbial biosignatures were collected throughout. We present here quantification of microbial biomass via fluorescence microscopy, preliminary analysis of nutrient addition experiments, data from sequencing of microbial 16S rRNA genes, analysis of microbial lipids, and data from Raman spectra of subsurface isolates. We initiated and sampled 12 nutrient addition experiments from 71-745 mbsf by adding sampled rocks to artificial seawater with no additions, added ammonium, added ammonium plus phosphate, and added organic acids. In nearly all of the experiment bottles, methane was detected when samples were collected at six months and again after one year of incubation. Phosphate in the incubations was drawn down, indicating active microbial metabolism, and archaeal lipids from in situ samples indicate the presence of methanogens, corroborating the likelihood of methanogens as the source of detected methane in the nutrient addition incubations. Altogether, the interdisciplinary approach used here provides a peek into life in the subseafloor upper ocean crust.

Investigating the effects of high temperature and a deep SMTZ on rock magnetic properties at Site C0023, IODP Expedition 370

NASA Astrophysics Data System (ADS)

Kars, M. A. C.; Henkel, S.

2017-12-01

In 2016, International Ocean Discovery Program (IODP) Expedition 370 drilled Site C0023 in the Nankai Trough, off Cape Muroto (Shikoku Island, Japan, NW Pacific Ocean). The aim of this expedition was to explore the limits of life in the deep subseafloor sediments in a high temperature environment (up to 120°C), and to investigate, among other objectives, the processes at the biotic-abiotic transition. A deep sulfate-methane transition zone (SMTZ) was identified between 630 and 750 meters below sea floor (mbsf). Based on the magnetic data profiles and results from previous ODP expeditions in the area, four magnetic zones were defined mostly reflecting changes in detrital supply and alteration/diagenetic features.Here, a rock magnetic study is conducted in order to document the downhole changes in magnetic properties and magnetic mineralogy (content, grain size and composition of the magnetic mineral assemblage) related to post-depositional diagenetic processes from 200 to 1100 mbsf, with a focus on the deep SMTZ. Natural remanent magnetization and its alternating-field demagnetization, magnetic susceptibility and acquisition of isothermal remanent magnetization are measured on 225 discrete samples for concentration and composition of the magnetic assemblage. Hysteresis properties and first order reversal curves are measured on respective dry powders for magnetic grain size study and composition of the magnetic assemblage. The preliminary rock magnetic results are presented and discussed based on the shipboard inorganic geochemical data.

IODP Expedition 360: Analyzing the Media Coverage of a High Profile Research Project

NASA Astrophysics Data System (ADS)

Kavanagh, L.; Martinez, A. O.; Burgio, M.; Zhang, J.; Expedition 360 Scientists, I.

2016-12-01

During Expedition 360 of the International Ocean Discovery Program (IODP), the JOIDES Resolution drilled 789 meters of lower crustal gabbro in the Southwest Indian Ocean. This hole began a multi-expedition project with the goal of one day drilling across the crust-mantle boundary for the first time. This simplified narrative of the research objectives struck a chord with media and the project received worldwide coverage in the form of over 50 stories with a total audience in the millions. This expedition is presented as a case study in science communication. A four-member education and outreach team onboard the ship acted as the point of contact for interested reporters. Major outlets that ran stories include the Australian Broadcasting Corporation, British Broadcasting Corporation, Boston Globe, Daily Express, Fox News, Nature, Smithsonian, and Chinese based Xinhua News Agency who sailed a reporter on the ship for the duration of the expedition. The majority of stories published provided accurate and favourable coverage of the project; however, a few contained critical errors and cast the expedition in a less positive light. Public reaction varied greatly depending on the article. Positive themes include interest in the scientific outcomes and encouragement of human exploration. Negative themes include the project being an inefficient use of money and a perceived risk of the drilling triggering an earthquake or volcano. Through a review of published articles and online comments, the successes and challenges faced by Expedition 360 are identified. Despite minimal preparation for media relations, the team successfully maintained a public profile while working in one of the most remote locations on Earth. Interviews were facilitated and videos, articles, and podcasts were produced onboard the ship. A simple, catchy narrative resulted in a large volume of coverage; however, this simplicity also formed the root of a number of misconceptions and issues of public concern.

IODP Expedition 337: Deep Coalbed Biosphere off Shimokita - Microbial processes and hydrocarbon system associated with deeply buried coalbed in the ocean

NASA Astrophysics Data System (ADS)

Inagaki, Fumio; Hinrichs, Kai-Uwe; Kubo, Yusuke; IODP Expedition 337 Scientists

2016-06-01

The Integrated Ocean Drilling Program (IODP) Expedition 337 was the first expedition dedicated to subseafloor microbiology that used riser-drilling technology with the drilling vessel Chikyu. The drilling Site C0020 is located in a forearc basin formed by the subduction of the Pacific Plate off the Shimokita Peninsula, Japan, at a water depth of 1180 m. Primary scientific objectives during Expedition 337 were to study the relationship between the deep microbial biosphere and a series of ˜ 2 km deep subseafloor coalbeds and to explore the limits of life in the deepest horizons ever probed by scientific ocean drilling. To address these scientific objectives, we penetrated a 2.466 km deep sedimentary sequence with a series of lignite layers buried around 2 km below the seafloor. The cored sediments, as well as cuttings and logging data, showed a record of dynamically changing depositional environments in the former forearc basin off the Shimokita Peninsula during the late Oligocene and Miocene, ranging from warm-temperate coastal backswamps to a cool water continental shelf. The occurrence of small microbial populations and their methanogenic activity were confirmed down to the bottom of the hole by microbiological and biogeochemical analyses. The factors controlling the size and viability of ultra-deep microbial communities in those warm sedimentary habitats could be the increase in demand of energy and water expended on the enzymatic repair of biomolecules as a function of the burial depth. Expedition 337 provided a test ground for the use of riser-drilling technology to address geobiological and biogeochemical objectives and was therefore a crucial step toward the next phase of deep scientific ocean drilling.

Influence of drilling operations on drilling mud gas monitoring during IODP Exp. 338 and 348

NASA Astrophysics Data System (ADS)

Hammerschmidt, Sebastian; Toczko, Sean; Kubo, Yusuke; Wiersberg, Thomas; Fuchida, Shigeshi; Kopf, Achim; Hirose, Takehiro; Saffer, Demian; Tobin, Harold; Expedition 348 Scientists, the

2014-05-01

The history of scientific ocean drilling has developed some new techniques and technologies for drilling science, dynamic positioning being one of the most famous. However, while industry has developed newer tools and techniques, only some of these have been used in scientific ocean drilling. The introduction of riser-drilling, which recirculates the drilling mud and returns to the platform solids and gases from the formation, to the International Ocean Drilling Program (IODP) through the launch of the Japan Agency of Marine Earth-Science and Technology (JAMSTEC) riser-drilling vessel D/V Chikyu, has made some of these techniques available to science. IODP Expedition 319 (NanTroSEIZE Stage 2: riser/riserless observatory) was the first such attempt, and among the tools and techniques used was drilling mud gas analysis. While industry regularly conducts drilling mud gas logging for safety concerns and reservoir evaluation, science is more interested in other components (e.g He, 222Rn) that are beyond the scope of typical mud logging services. Drilling mud gas logging simply examines the gases released into the drilling mud as part of the drilling process; the bit breaks and grinds the formation, releasing any trapped gases. These then circulate within the "closed circuit" mud-flow back to the drilling rig, where a degasser extracts these gases and passes them on to a dedicated mud gas logging unit. The unit contains gas chromatographs, mass spectrometers, spectral analyzers, radon gas analyzers, and a methane carbon isotope analyzer. Data are collected and stored in a database, together with several drilling parameters (rate of penetration, mud density, etc.). This initial attempt was further refined during IODP Expeditions 337 (Deep Coalbed Biosphere off Shimokita), 338 (NanTroSEIZE Stage 3: NanTroSEIZE Plate Boundary Deep Riser 2) and finally 348 (NanTroSEIZE Stage 3: NanTroSEIZE Plate Boundary Deep Riser 3). Although still in its development stage for scientific application, this technique can provide a valuable suite of measurements to complement more traditional IODP shipboard measurements. Here we present unpublished data from IODP Expeditions 338 and 348, penetrating the Nankai Accretionary wedge to 3058.5 meters below seafloor. Increasing mud density decreased degasser efficiency, especially for higher hydrocarbons. Blurring of the relative variations in total gas by depth was observed, and confirmed with comparison to headspace gas concentrations from the cored interval. Theoretically, overpressured zones in the formation can be identified through C2/C3 ratios, but these ratios are highly affected by changing drilling parameters. Proper mud gas evaluations will need to carefully consider the effects of variable drilling parameters when designing experiments and interpreting the data.

Drilling into the deep interior of the Nankai accretionary prism: Preliminary results of IODP NanTroSEIZE Expedition 348

NASA Astrophysics Data System (ADS)

Tobin, H. J.; Hirose, T.; Saffer, D. M.; Toczko, S.; Maeda, L.

2014-12-01

International Ocean Discovery Program (IODP) Expedition 348, the latest advance of the NanTroSEIZE project, started on 13 September 2013 and was completed on 29 January 2014. During Expedition 348, the drilling vessel Chikyu advanced the ultra-deep riser hole at Site C0002, located 80 km offshore of the Kii Peninsula, from a depth of 860 meters below sea floor (mbsf) to 3058.5 mbsf, the world record for the deepest scientific ocean drilling, and cased it for future deepening. The drilling operation successfully obtained data on formation physical properties from logging while drilling (LWD) tools, as well as from lithological analyses of cuttings and core from the interior of the active accretionary prism at the Nankai Trough. IODP Site C0002 is the currently only borehole to access the deep interior of an active convergent margin. Preliminary scientific results of Expedition 348 are as follows: (1) Fine-grained turbiditic mudstones with coarser silty and sandy interbeds, exhibiting steep dips (between ~60 and 90 degrees) are predominant in the prism down to ~3000 mbsf. The biostratigraphic age of the sediments in the lowermost part of the hole is thought to be 9-11 Ma, with an assumed age of accretion of 3-5 Ma. (2) Slickenlined surfaces, deformation bands and mineral veins are present throughout the drilled interval, while well-developed scaly clay fabrics are increasingly observed below ~2200 mbsf. A substantial fault zone with well-developed foliation was successfully cored from the deep interior of the prism at ~2205 mbsf. (3) Porosity generally decreases from ~60% to ~20% from the seafloor to 3000 mbsf. However, physical properties including grain density, electrical conductivity and P-wave velocity suggest fairly homogeneous properties in the interior of the prism between ~2000 and 3000 mbsf. (4) Mud gas analysis during the riser drilling indicates that a source of methane gas shifts from microbial origin to thermogenic at around 2325 mbsf. (5) The maximum horizontal principal stress at ~2200 mbsf is in the NE-SW direction. The inner wedge at ~ 2000 mbsf is currently in a strike-slip stress regime.

High Resolution Vertical Seismic Profile from the Chicxulub IODP/ICDP Expedition 364 Borehole: Wave Speeds and Seismic Reflectivity.

NASA Astrophysics Data System (ADS)

Nixon, C.; Kofman, R.; Schmitt, D. R.; Lofi, J.; Gulick, S. P. S.; Christeson, G. L.; Saustrup, S., Sr.; Morgan, J. V.

2017-12-01

We acquired a closely-spaced vertical seismic profile (VSP) in the Chicxulub K-Pg Impact Crater drilling program borehole to calibrate the existing surface seismic profiles and provide complementary measurements of in situ seismic wave speeds. Downhole seismic records were obtained at spacings ranging from 1.25 m to 5 m along the borehole from 47.5 m to 1325 mwsf (meters wireline below sea floor) (Fig 1a) using a Sercel SlimwaveTM geophone chain (University of Alberta). The seismic source was a 30/30ci Sercel Mini GI airgun (University of Texas), fired a minimum of 5 times per station. Seismic data processing used a combination of a commercial processing package (Schlumberger's VISTA) and MatlabTM codes. The VSP displays detailed reflectivity (Fig. 1a) with the strongest reflection seen at 600 mwsf (280 ms one-way time), geologically corresponding to the sharp contact between the post-impact sediments and the target peak ring rock, thus confirming the pre-drilling interpretations of the seismic profiles. A two-way time trace extracted from the separated up-going wavefield matches the major reflection both in travel time and character. In the granitic rocks that form the peak ring of the Chicxulub impact crater, we observe P-wave velocities of 4000-4500 m/s which are significantly less than the expected values of granitoids ( 6000 m/s) (Fig. 1b). The VSP measured wave speeds are confirmed against downhole sonic logging and in laboratory velocimetry measurements; these data provide additional evidence that the crustal material displaced by the impact experienced a significant amount of damage. Samples and data provided by IODP. Samples can be requested at http://web.iodp.tamu.edu/sdrm after 19 October 2017. Expedition 364 was jointly funded by ECORD, ICDP, and IODP with contributions and logistical support from the Yucatan State Government and UNAM. The downhole seismic chain and wireline system is funded by grants to DRS from the Canada Foundation for Innovation and the Alberta Enterprise and Advanced Education Grants Program.

Overpressure, Flow Focusing, Compaction and Slope Stability on the continental slope: Insights from IODP Expedition 308

NASA Astrophysics Data System (ADS)

Flemings, P. B.

2010-12-01

Integrated Ocean Drilling Program Expepedition 308 used direct measurements of pore pressure, analysis of hydromechanical properties, and geological analysis to illuminate how sedimentation, flow focusing, overpressure, and slope stability couple beneath the seafloor on the deepwater continental slope in the Gulf of Mexico. We used pore pressure penetrometers to measure severe overpressures (60% of the difference between lithostatic stress and hydrostatic pressure) that extend from the seafloor for 100’s of meters. We ran uniaxial consolidation experiments on whole core and found that although permeability is relatively high near the seafloor, the sediments are highly compressible. As a result, the coefficient of consolidation (the hydraulic diffusivity) is remarkably constant over a large range of effective stresses. This behavior accounts for the high overpressure that begins near the seafloor and extends to depth. Forward modeling suggests that flow is driven laterally along a permeable unit called the Blue Unit. Calculations suggest that soon after deposition, lateral flow lowered the effective stress and triggered the submarine landslides that we observe. Later in the evolution of this system, overpressure may have pre-conditioned the slope to failure by earthquakes. Results from IODP Expedition 308 illustrate how pore pressure and sedimentation control the large-scale form of continental margins, how submarine landslides form, and provide strategies for designing stable drilling programs.

Porosity-depth trends of carbonate deposits along the northwest shelf of Australia (IODP Expedition 356)

NASA Astrophysics Data System (ADS)

Lee, Eun Young; Kominz, Michelle; Reuning, Lars; Takayanagi, Hideko; Knierzinger, Wolfgang; Wagreich, Michael; Expedition 356 shipboard scientists, IODP

2017-04-01

The northwest shelf (NWS) of Australia extends from northern tropical to southern temperate latitudes situated offshore from the low-moderate-relief and semi-arid Australian continent. The shelf environment is dominated throughout by carbonate sedimentation with warm-water and tropical carbonate deposits, connected to the long-term northward drift of Australia bringing the NWS into tropical latitudes. IODP expedition 356 cored seven sites (U1458-U1464) covering a latitudinal range of 29°S-18°S off the NWS. This study focuses on porosity-depth trends of the Miocene - Pleistocene carbonate sediment on the NWS. The NWS is an ideal area to study regional (and furthermore general) carbonate porosity-depth relationships, because it contains a nearly continuous sequence of carbonate sediment ranging in depth from the surface to about 1,100m and in age from Pleistocene to Miocene. Porosity-depth trends of sedimentary rocks are generally controlled by a variety of factors which govern the rates of porosity loss due to mechanical compaction and of porosity loss (or gain) due to chemical processes during diagenesis. This study derives porosity data from Moisture and Density (MAD) technique conducted during IODP Expedition 356. MAD samples were collected from packstone (44%), wackestone (27%), mudstone (15%) and grainstone (7%), with the rest from floatstone, rudstone, dolostone, sandstone and other subordinate lithologies. To understand porosity-depth trends, the porosity data are arranged both exponentially and linearly, and correlated with age models and lithologic descriptions provided by IODP shipboard scientists. Porosity(%)-depth(m) trends of all the porosity data are Porosity=52e-0.0008/Depth (exponential) and Porosity=-0.03Depth+52 (linear). Porosities near surface and in the deepest parts of each well are least well represented by these trend lines. Porosity values of Pleistocene sediment are generally higher than those of Miocene - Pliocene sediment. The initial porosity in porosity-depth trends increases from 52% to 57% with increasing mud content from grainstone to packstone, wackestone, and mudstone. Carbonate sediment that includes non-skeletal grains usually has lower porosity values than the trend lines. *This research was a part of the project titled 'International Ocean Discovery Program', funded by the Ministry of Oceans and Fisheries, Korea.

Battling through the thermal boundary layer: Deep sampling in ODP Hole 1256D during IODP Expedition 335

NASA Astrophysics Data System (ADS)

Ildefonse, B.; Teagle, D. A.; Blum, P.; IODP Expedition 335 Scientists

2011-12-01

IODP Expedition 335 "Superfast Spreading Rate Crust 4" returned to ODP Hole 1256D with the intent of deepening this reference penetration of intact ocean crust several hundred meters into cumulate gabbros. This was the fourth cruise of the superfast campaign to understand the formation of oceanic crust accreted at fast spreading ridges, by exploiting the inverse relationship between spreading rate and the depth to low velocity zones seismically imaged at active mid-ocean zones, thought to be magma chambers. Site 1256 is located on 15-million-year-old crust formed at the East Pacific Rise during an episode of superfast ocean spreading (>200 mm/yr full rate). Three earlier cruises to Hole 1256D have drilled through the sediments, lavas and dikes and 100 m into a complex dike-gabbro transition zone. The specific objectives of IODP Expedition 335 were to: (1) test models of magmatic accretion at fast spreading ocean ridges; (2) quantify the vigor of hydrothermal cooling of the lower crust; (3) establish the geological meaning of the seismic Layer 2-3 boundary at Site 1256; and (4) estimate the contribution of lower crustal gabbros to marine magnetic anomalies. It was anticipated that even a shortened IODP Expedition could deepen Hole 1256D a significant distance (300 m) into cumulate gabbros. Operations on IODP Expedition 335 proved challenging from the outset with almost three weeks spent re-opening and securing unstable sections of the Hole. When coring commenced, the destruction of a hard-formation C9 rotary coring bit at the bottom of the hole required further remedial operations to remove junk and huge volumes of accumulated drill cuttings. Hole-cleaning operations using junk baskets returned large samples of a contact-metamorphic aureole between the sheeted dikes and a major heat source below. These large (up to 3.5 kg) irregular samples preserve magmatic, hydrothermal and structural relationships hitherto unseen because of the narrow diameter of drill core and previous poor core recovery. Including the ~60 m-thick zone of granoblastic dikes overlying the uppermost gabbro, the dike-gabbro transition zone at Site 1256 is over 170 m thick, of which more than 100 m are recrystallized granoblastic basalts. This zone records a dynamically evolving thermal boundary layer between the principally hydrothermal domain of the upper crust and a deeper zone of intrusive magmatism. The recovered samples document a sequence of evolving geological conditions and the intimate coupling between temporally and spatially intercalated intrusive, hydrothermal, contact-metamorphic, partial melting and retrogressive processes. Despite the operational challenges, we achieved a minor depth advance to 1522 m, but this was insufficient penetration to complete any of the primary objectives. However, Hole 1256D has been thoroughly cleared of junk and drill cuttings that have hampered operations during this and previous Expeditions. At the end of Expedition 335, we briefly resumed coring and stabilized problematic intervals with cement. Hole 1256D is open to its full depth and ready for further deepening in the near future.

Temperature measurements at IODP 337 Expedition, off Shimokita, NE Japan.

NASA Astrophysics Data System (ADS)

Yamada, Y.; Sanada, Y.; Moe, K.; Kubo, Y.; Inagaki, F.

2014-12-01

Precise estimation of underground temperature is a challenging issue, since direct measurements require drill holes that disturb the original underground environment. During IODP 337 expedition, we have obtained in-situ temperature datasets for several times by using geophysical logging tools. A common procedure to estimate the undisturbed maximum underground temperature is by approximating that the 'build-up' pattern of measured values in the borehole should reach to the equilibrium temperature. At the Shimokita site, this was 63.7 oC at a depth of 2466 m. We have much more measurement dataset and all of these were used to analyze detailed in-site temperatures at various depths. The result shows a non-linear temperature profile to the depth and this may be reflected by the thermal properties of the surrounding rocks.

Potential sulfate reduction in deeply buried coalbeds 2 km below the seafloor off the Shimokita Peninsula (Japan)

NASA Astrophysics Data System (ADS)

Glombitza, C.; Inagaki, F.; Lever, M. A.; Jørgensen, B. B.

2013-12-01

Integrated Ocean Drilling Program (IODP) Expedition 337 aboard the drilling vessel Chikyu in summer 2012 was the first IODP expedition to drill into a deeply buried hydrocarbon system by riser drilling and, in the process, extended the depth record of scientific ocean drilling to 2466 meters below seafloor (mbsf). A main scientific goal of Expedition 337 was to explore microbial communities associated with deeply buried coalbeds 2 km below the seafloor at Site C0020 off the Shimokita Peninsula of Japan, northwestern coast of the Pacific Ocean. Four lithological units were defined according to sedimentological observations (Inagaki et al. 2012). Temperature measurements during wireline logging revealed in-situ temperatures in the range habitable for life, with ~40-45°C in 2km-deep coalbeds and 60°C at the bottom of the hole. To determine potential sulfate reduction rates (pSRRs) throughout the lower half of the borehole (1200-2466 mbsf; Units II - IV), we prepared slurries from fresh core material in artificial seawater medium containing 1 mM of sulfate and incubated these onboard with 35S-labeled sulfate at approximate in-situ temperatures (i.e., 25, 35, and 45°C). A duplicate set of incubations was started from each sample, one with only N2 in the headspace, and one with N2 + CH4 in the headspace. We incubated samples with 3.7 MBq 35S for a period of 10 days to achieve a detection limit of ca. 10 fmol sulfate cm-3 d-1. pSRRs were close to the detection limit in Unit II and increased by two orders of magnitude up to 2 pmol cm-3 d-1 in the coal-bearing strata (Unit III), decreasing again below in Unit IV. Maximum rates in Unit III reached values similar to those determined during the Chikyu shakedown cruise at 350 mbsf at the same site in 2006. In contrast to the pSRRs determined previously, however, addition of methane did not stimulate pSRRs, suggesting that potential sulfate reduction was supported by electron donors other than methane. The increase of pSRR in the coal-bearing unit is in accordance with other indicators of increased microbial activity in this depth interval, such as high C1/C2 ratios with low 13C/12C isotope ratios of methane observed by real-time mud gas logging during riser drilling. Inagaki, F., K.-U. Hinrichs, Y. Kubo, and the Expedition 337 Scientists (2012), Deep coalbed biosphere off Shimokita: microbial processes and hydrocarbon system associated with deeply buried coalbed in the ocean, IODP Prel. Rept., 337, doi: 10.2204/iodp.pr.337.2012

Pleistocene calcareous nannofossil biochronology at IODP Site U1385 (Expedition 339)

NASA Astrophysics Data System (ADS)

Balestra, B.; Flores, J.-A.; Hodell, D. A.; Hernández-Molina, F. J.; Stow, D. A. V.

2015-12-01

During Integrated Ocean Drilling Program (IODP) Expedition 339, Site U1385 (37°34‧N, 10°7‧W, 2578 m below sea level) was drilled in the lower slope of the Portuguese margin, to provide a marine reference section of Pleistocene millennial-scale climate variability. Five holes were cored using the Advanced Piston Corer (APC) to a depth of ~ 151 m below sea floor (mbsf) recovering a continuous stratigraphic record covering the past 1.4 Ma. Here we present results of the succession of standard and unconventional calcareous nannofossil biostratigraphic events. The quantitative study of calcareous nannofossils showed well-preserved and abundant assemblages throughout the core. Most conventional Pleistocene events were recognized and the timing of bioevents were calibrated using correlation to the new oxygen isotope stratigraphy record developed for the Site U1385. The analyses provide further data on the stratigraphic distribution of selected species and genera, such as the large Emiliania huxleyi (> 4 μm), Gephyrocapsa caribbeanica, Helicosphaera inversa, Gephyrocapsa omega and Reticulofenestra asanoi (> 6 μm) and other circular-subcircular small reticulofenestrids, resulting in new insights into the environmental control of their stratigraphic patterns. Finally, the comparison between nannofossil datums and oxygen isotope stratigraphy on the same samples has resulted in an accurate revision of timing of the events, providing valuable biochronologic information.

Igneous stratigraphy and rock-types from a deep transect of the gabbroic lower crust of the Atlantis Bank core complex (SW Indian Ridge): preliminary results from IODP Expedition 360

NASA Astrophysics Data System (ADS)

Sanfilippo, A.; France, L.; Ghosh, B.; Liu, C. Z.; Morishita, T.; Natland, J. H.; Dick, H. J.; MacLeod, C. J.; Expedition 360 Scientists, I.

2016-12-01

International Ocean Discovery Program (IODP) Expedition 360 represents the first leg of a multi-phase drilling programme ('SloMo' project) aimed at investigating the nature of the lower crust and Moho at slow spreading ridges. As an initial phase of the SloMo project, IODP Exp. 360 intended to recover a representative transect of the lower oceanic crust formed at Atlantis Bank, an oceanic core complex on the SW Indian Ridge. During this expedition, 89 cores of gabbroic rocks were recovered at Hole U1473A, drilled to 789.7 m below seafloor. This hole was subsequently deepened to 809.4 mbsf during transit Expedition 362T, which recovered additional 7 cores. The gabbroic section recovered at Hole U1473A consists of several types of gabbro, diabase, and felsic veins. The main lithology is dominated by olivine gabbro (76.5% in abundance), followed by gabbro containing 1-2% oxide (9.5%), gabbro with >2% oxide (7.4%), gabbro sensu stricto (5.1%), felsic veins (1.5%) and diabase (<0.5%). The different lithologies appear randomly distributed throughout the section, although oxide abundance seems to decrease slightly downhole, except for the lowermost intervals where oxide gabbros are more abundant. Based on changes in rock types, grain size, texture, and the occurrence of felsic material, we identified eight lithologic units, which locally define separate geochemical trends. Each unit is characterized by meter-scale heterogeneity which classically characterizes gabbros formed at slow spreading ridges. Reaction textures in olivine gabbros, crosscutting relationships between oxide gabbros and host rocks, the presence of intrusive to sutured contacts, igneous layering and the widespread occurrence of felsic veins and segregations indicate that the evolution of this section was controlled by complicated interactions of magmatic processes, e.g., fractional crystallization, melt-rock reaction, late-stage melt migration, which were active in a crystal mush formed by multiple injections of magma. This contribution describes the main features of these rocks and discusses the complexity of the igneous processes producing this 800 m-long transect of oceanic crust that was formed in a robust magmatic segment of an ultraslow spreading ridge.

Paleomagnetic results from IODP Expedition 344 Site U1381 and implications for the initial subduction of the Cocos Ridge

NASA Astrophysics Data System (ADS)

Li, Yong-Xiang; Zhao, Xixi; Jovane, Luigi; Petronotis, Katerina; Gong, Zheng; Xie, Siyi

2016-04-01

Understanding the processes that govern the strength, nature, and distribution of slip along subduction zones is a fundamental and societally relevant goal of modern earth science. The Costa Rica Seismogenesis Project (CRISP) is specially designed to understand the processes that control nucleation and seismic rupture of large earthquakes at erosional subduction zones. Drilling directly on the Cocos Ridge (CR) during International Ocean Drilling Program (IODP) Expedition 344 discovered a sedimentary hiatus in Site U1381 cores. In this study, we conducted a magnetostratigraphic and rock magnetic study on the Cenozoic sedimentary sequences of site U1381. Anisotropy of magnetic susceptibility data from sediments above and below the hiatus show oblate fabrcis, but the Kmin axes of the AMS data from sediments below the hiatus are more dispersed than those from sediments above the hiatus, implying that formation of hiatus may have affected AMS. Paleomagnetic results of the U1381 core, together with available Ar-Ar dates of ash layers from sediments below the hiatus, allow us to establish a geomagnetic polarity timescale that brackets the hiatus between ca. 9.61 and 1.52 Ma. Analyses of sedimentary records from ODP/IODP cores in the vicinity reveal that the hiatus appears to be regional, spanning the northeastern end of the CR. Also, the hiatus appears to occur only at certain locations. Its regional occurrence at unique locations implies a link to the initial shallow subduction of the Cocos Ridge. The hiatus was probably produced by either bottom current erosion or the CR buckling upon its initial collision with the Middle American trench (MAT). Thus, the initial subduction of the CR must have taken place on or before 1.52 Ma.

Initial results from the Nankai Trough shallow splay and frontal thrust (IODP Expedition 316): Implications for fluid flow

NASA Astrophysics Data System (ADS)

Screaton, E.; Kimura, G.; Curewitz, D.; Scientists, E.

2008-12-01

Integrated Ocean Drilling Program (IODP) Expedition 316 examined the frontal thrust and the shallow portion of the megasplay fault offshore of the Kii peninsula, and was the third drilling expedition of the Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE). NanTroSEIZE will integrate seafloor observations, drilling, and observatories to investigate the processes controlling slip along subduction zone plate boundary fault systems. Site C0004 examined a shallow portion of the splay fault system where it overrides slope basin sediments. Site C0008, located in the slope basin 1 km seaward of Site C0004, provided a reference site for the footwall sediments. Results of drilling indicate that the footwall sediments have dewatered significantly, suggesting permeable routes for fluid escape. These high-permeability pathways might be provided by coarse-grained layers within the slope sediments. In situ dewatering and multiple fluid escape paths will tend to obscure any geochemical signature of flow from depth. Sites C0006 and C0007 examined the frontal thrust system. Although poorly recovered, coarse-grained trench sediments were sampled within the footwall. These permeable sediments would be expected to allow rapid escape of any fluid pressures due to loading. At both sites, low porosities are observed at shallow depths, suggesting removal of overlying material. This observation is consistent with interpretations that the prism is unstable and currently in a period of collapse. Anomalously low temperatures were measured within boreholes at these sites. One possible explanation for the low temperatures is circulation of seawater along normal faults in the unstable prism.

Fresh and Salt Water Distribution in Passive Margin Sediments: Insights from Iodp Expedition 313 ON the New Jersey Margin

NASA Astrophysics Data System (ADS)

Lofi, J.; Inwood, J.; Proust, J.; Monteverde, D.; Loggia, D.; Basile, C.; Hayashi, T.; Stadler, S.; Fehr, A.; Pezard, P.

2012-12-01

For the first time in the history of international scientific drillings, the Integrated Ocean Drilling Program (IODP) mission-specific platform (MSP) Expedition 313 drilled three 631-755 m-deep boreholes on the middle shelf of a clastic passive margin. This expedition gathered a full set of geophysical data tied to drillcores with 80% of recovery. It offers a unique opportunity to access the internal structure of a siliciclastic system, at scales ranging from the matrix to the margin, and to correlate the geological skeleton with the spatial distribution and salinity of saturating fluids. In addition to the discovery of very low salinity pore water (<3g/l) at depths exceeding 400 m below the middle shelf, this expedition provides evidence for a multi-layered reservoir, with fresh/brackish water intervals alternating vertically with salty intervals. Our observations suggest that the processes controlling salinity distribution are strongly influenced by lithology, porosity and permeability. Saltier pore waters are recovered in less porous, more permeable, intervals whereas fresher pore waters are recovered in more porous, less permeable, intervals. Pore water concentrations are inversely correlated to the Thorium content, with high salinities in low Th intervals (i.e. sandy formations). The transition from fresher to saltier intervals is often marked by cemented horizons acting as permeability barrier. In the lower part of some holes, the salinity varies independently of lithology, suggesting different mechanisms and/or sources of salinity. We have developed a 2D model of permeability distribution along a dip transect of the margin, extrapolated from combined clinoform geometries observed on seismic data and sedimentary facies described on cores. This model clearly illustrates the importance of taking into account the spatial heterogeneity of geological system at several scales. Lithology reflects permeability at a small scale whereas seismic facies and system tracts can be used to infer the reservoir geometry at a larger scale. Four main reservoirs (R1 to R4) that are relatively disconnected have been identified. These are essentially developed in coarse-grained deposits observed either in some clinoform topsets (R4), in upper foresets (R2, R3), or in both of them (R1). R2 to R4 contain salty water while the most proximal reservoir R1, located close to the coastline, is saturated with fresh water, and may form the seaward extension of onshore aquifers. Each of these four reservoirs is separated by confining units of varied thicknesses and of relatively broad spatial extension. At the Expedition 313 drilling sites, the fresh waters stored in confining units have a post-deposition age and may have a fossil origin (Pleistocene low-stands?), whereas saltier water recovered in distal reservoirs (R2 to R4) penetrated at a later stage. Further work must be done to clarify the emplacement mechanisms. Future studies should focus on the inclusion of our 2D permeability model in a groundwater model, in order to examine the specific flow processes that are active in this environment. This research used samples and data provided by the Integrated Ocean Drilling Program (IODP) and the International Continental Scientific Drilling Program (ICDP).

Ocean Drilling Program: Science Operator

Science.gov Websites

: www.odplegacy.org Integrated Ocean Drilling Program (IODP): www.iodp.org IODP U.S. Implementing Organization (IODP -USIO): www.iodp-usio.org The Ocean Drilling Program (ODP) was funded by the U.S. National Science Foundation and 22 international partners (JOIDES) to conduct basic research into the history of the ocean

New access to the deep interior of the Nankai accretionary complex and comprehensive characterization of subduction inputs and recent mega splay fault activity (IODP-NanTroSEIZE Expedition 338)

NASA Astrophysics Data System (ADS)

Strasser, Michael; Moore, Gregory F.; Kanagawa, Kyuichi; Dugan, Brandon; Fabbri, Olivier; Toczko, Sean; Maeda, Lena

2013-04-01

The Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) is a coordinated, multi-expedition Integrated Ocean Drilling Program (IODP) drilling project designed to investigate fault mechanics and seismogenesis along subduction megathrusts through direct sampling, in situ measurements, and long-term monitoring in conjunction with allied laboratory and numerical modeling studies. IODP Expedition 338 (1 October 2012 - 13 January 2013), extended riser Hole C0002F from 856 meters below the sea floor (mbsf) to 2005 mbsf. Site C0002 is the centerpiece of the NanTroSEIZE project, and is planned to be deepened to eventually reach the seismogenic fault zone during upcoming drilling expeditions. The original Exp. 338 operational plan to case the hole to 3600 mbsf had to be revised as sudden changes in sea conditions resulted in damage to parts of the riser system, thus the hole was suspended at 2005 mbsf but left for future re-entry. The revised operation plan included additional riserless logging and coring of key targets not sampled during previous NanTroSEIZE expeditions, but relevant to comprehensively characterize the alteration stage of the oceanic basement input to the subduction zone, the early stage of Kumano Basin evolution and the recent activity of the shallow mega splay fault zone system and submarine landslides. Here we present preliminary results from IODP Exp. 338: Logging While Drilling (LWD), mud gas monitoring and analysis on cuttings from the deep riser hole characterize two lithological units within the internal accretionary prism, separated by a prominent fault zone at ~1640 mbsf. Internal style of deformation, downhole increase of thermogenically formed formation gas and evidence for mechanical compaction and cementation document a complex structural evolution and provide unprecedented insights into the mechanical state and behavior of the wedge at depth. Additionally, multiple samples of the unconformity between the Kumano Basin and accretionary prism at Site C0002 shed new light on this debatable unconformity boundary and suggest variable erosional processes active on small spatial scales. Results from riserless drilling at input Site C0012 include 178.7 m of detailed LWD characterization of the oceanic basement, indicating an upper ~100 m zone of altered pillow basalts and sheet flow deposits, and a lower, presumably less altered basement unit without indication for interlayered sediment horizons. Low angle faults identified in X-ray Computed Tomography images and structural investigation on cores from Site C0022, located in the slope basin immediately seaward of the megasplay fault zone, indicate splay-fault-related, out-of-sequence thrusting within slope basin sediments and shed new light on recent activity of the megasplay. Lastly, Exp. 338 added additional coring to improve our understanding of submarine landslides in the slope basins seaward of the splay fault and yields new LWD data to characterize in situ internal structures and properties of mass-transport deposits as it relates to the dynamics and kinematics of submarine landslides.

Microbiology of the lower ocean crust - Preliminary results from IODP Expedition 360, Atlantis Bank

NASA Astrophysics Data System (ADS)

Sylvan, J. B.; Edgcomb, V. P.; Burgaud, G.; Klein, F.; Schubotz, F.; Expedition 360 Scientists, I.

2016-12-01

International Ocean Discovery Program (IODP) Expedition 360 represents the first leg of a multi-phase drilling program, SloMo, aimed at investigating the nature of the lower crust and Moho at slow spreading ridges. The goal of Expedition 360 was to recover a representative transect of the lower oceanic crust formed at Atlantis Bank, an oceanic core complex on the SW Indian Ridge. We present here preliminary analysis of microbial communities sampled from Hole U1473A, drilled to 789.7 m below seafloor during Expedition 360. Sub-sampling of core sections was conducted in a newly designed plexiglass enclosure with positive air pressure and HEPA filtered air, providing a clean environment for microbiology sampling aboard the JOIDES Resolution. Adenosine triphosphoate, an indicator of microbial biomass, was quantified above detection in 23 of 66 samples analyzed. We measured exoenzyme activity for alkaline phosphatase (AP), leucine aminopeptidase and arginine aminopeptidase in 16 samples and found AP to be very low but above background for 14 of the samples, with highest activities measured between 10 and 70 m below seafloor (mbsf) and peaks again at 158 and 307 mbsf, while both peptidase enzymes were above detection for only one sample at 715 mbsf. Isolates of fungi obtained from core samples as well as analyses of lipid and DNA biomarkers, and Raman spectra for a few of our rock core samples provide initial insights into microbial communities in the lower oceanic crust. Finally, a new tracer of seawater and drilling mud contamination, perfluoromethyl decaline (PFMD), was tested for the first time and its performance compared with the commonly used tracer perfluoromethylcyclohexane (PMCH). PFMD was run during coring operations for ten samples and was routinely detected in the drilling fluids, usually detected on the outside of uncleaned cores, and rarely above detection on the cleaned outside of cores. It was below detection on the inside of cores, indicating penetration of drill fluids to the interior of whole round drill cores, where we collected our samples, is unlikely.

Interpretation of a leak-off test conducted near the bottom of the Kumano Forearc Basin strata at IODP Site C0002 in the Nankai accretionary complex, SW Japan

NASA Astrophysics Data System (ADS)

Song, I.; Huepers, A.; Olcott, K. A.; Saffer, D. M.; Dugan, B.; Strasser, M.

2013-12-01

The Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) is a long-term, multi-stage scientific drilling project launched for investigating fault mechanics and seismogenesis along subduction megathrusts. One main key to the mechanics of the plate boundary is understanding the absolute mechanical strength and the in situ stress along the megathrust. As part of efforts to access the Nankai Trough seismogenic zone, the NanTroSEIZE Integrated Ocean Drilling Program (IODP) project began riser-based drilling operations at Site C0002 (Hole C0002F) in 2010 during IODP Expedition 326, with the objective of reaching the plate interface at ~6800 meters below the seafloor (mbsf). The geology in this area is composed of the Kumano Forearc Basin sedimentary strata to ~940 mbsf, underlain by the inner accretionary wedge. IODP Expedition 326 drilled Hole C0002F to 872.5 mbsf, near the bottom of the Kumano Basin, and set a 20-inch casing string to 860.2 mbsf. During IODP Expedition 338 in 2012, the hole was extended to 2005.5 mbsf. At the beginning of the operation, a leak-off test (LOT) was conducted in the interval of 872.5-875.5 mbsf, to define the maximum mud weight for the next stage of logging-while-drilling (LWD). Drilling-out-cement (DOC) at the bottom of the hole prior to the LOT provided a 3-m long, 17-inch diameter open borehole for the LOT. For the LOT, this open hole interval was pressurized with the outer annulus closed by the blow out preventer (BOP) using drilling mud of density of 1100 kg/m3, and mud pressure was measured at the cement pumps. The bottom-hole pressure was calculated by the recorded pressure plus the static pressure of the mud column. The first cycle of pressurization was conducted with injection of drilling mud at 31.8 l/min. However, the leak-off pressure (LOP) was not clearly defined because a large volume of mud was lost. Therefore a second cycle was conducted with a higher drilling mud injection rate (47.7 l /min). The rapid increase in pressure with a lower volume of mud injected during the second cycle suggests that a good mud cake was formed around the borehole wall, possibly due to mud flowing into the formation during the first cycle. In the second cycle, we identify a LOP of ~32.0 MPa from the pressure-volume record, which we interpret as the least principal stress. The total vertical stress given by the integration of bulk density with respect to depth is 35.7 MPa, indicating that the LOP reflects the least horizontal stress. This result can be a solid basis to constrain the in situ state of stress from indirect stress indicators such as wellbore failures at other depths.

Hess Deep Interactive Lab: Exploring the Structure and Formation of the Oceanic Crust through Hands-On Models and Online Tools

NASA Astrophysics Data System (ADS)

Kurtz, N.; Marks, N.; Cooper, S. K.

2014-12-01

Scientific ocean drilling through the International Ocean Discovery Program (IODP) has contributed extensively to our knowledge of Earth systems science. However, many of its methods and discoveries can seem abstract and complicated for students. Collaborations between scientists and educators/artists to create accurate yet engaging demonstrations and activities have been crucial to increasing understanding and stimulating interest in fascinating geological topics. One such collaboration, which came out of Expedition 345 to the Hess Deep Rift, resulted in an interactive lab to explore sampling rocks from the usually inacessible lower oceanic crust, offering an insight into the geological processes that form the structure of the Earth's crust. This Hess Deep Interactive Lab aims to explain several significant discoveries made by oceanic drilling utilizing images of actual thin sections and core samples recovered from IODP expeditions. . Participants can interact with a physical model to learn about the coring and drilling processes, and gain an understanding of seafloor structures. The collaboration of this lab developed as a need to explain fundamental notions of the ocean crust formed at fast-spreading ridges. A complementary interactive online lab can be accessed at www.joidesresolution.org for students to engage further with these concepts. This project explores the relationship between physical and on-line models to further understanding, including what we can learn from the pros and cons of each.

Terrestrial Palynology of Paleocene and Eocene Sediments Above the Chicxulub Impact Crater

NASA Astrophysics Data System (ADS)

Smith, V.; Warny, S.; Bralower, T. J.; Jones, H.; Lowery, C. M.; Smit, J.; Vajda, V.; Vellekoop, J.; 364 Scientists, E.

2017-12-01

International Ocean Discovery Program (IODP) Expedition 364, with support from the International Continental Scientific Drilling Program, cored through Paleocene and Eocene sediments and into the impact structure of the Chicxulub impact crater. Three palynological studies of the post-impact section are currently underway. The two other studies are investigating the dinoflagellate palynology and terrestrial palynology of the K/Pg boundary section, while this study focuses on the early Eocene terrestrial palynology of the IODP 364 core, which has yielded a diverse and well preserved pollen assemblage. A few samples from the Early Paleocene have also been examined but organic microfossil preservation is quite poor. Samples from this core are the oldest palynological record from the Yucatan peninsula. Sample preparation and detailed abundance counts of sixty samples throughout the post-impact section are in progress, with a particular focus on the Paleocene-Eocene Thermal Maximum (PETM) and the Early Eocene Climatic Optimum (EECO). Terrestrial palynomorph assemblages will be used to reconstruct paleoclimatological conditions throughout this time period. Floral response to hyperthermal events in the IODP 364 core will be compared with records from other Gulf of Mexico and Caribbean sections. In addition to the biological and paleoclimatological implications of this research, age control from foraminiferal and nannofossil biostratigraphy, paleomagnetism, and radiometric dating will provide a chronological framework for the terrestrial pollen biostratigraphy, with applications to hydrocarbon exploration in the Wilcox Formation and age equivalent sections in the Gulf of Mexico.

The ``Adopt A Microbe'' project: Web-based interactive education connected with scientific ocean drilling

NASA Astrophysics Data System (ADS)

Orcutt, B. N.; Bowman, D.; Turner, A.; Inderbitzen, K. E.; Fisher, A. T.; Peart, L. W.; Iodp Expedition 327 Shipboard Party

2010-12-01

We launched the "Adopt a Microbe" project as part of Integrated Ocean Drilling Program (IODP) Expedition 327 in Summer 2010. This eight-week-long education and outreach effort was run by shipboard scientists and educators from the research vessel JOIDES Resolution, using a web site (https://sites.google.com/site/adoptamicrobe) to engage students of all ages in an exploration of the deep biosphere inhabiting the upper ocean crust. Participants were initially introduced to a cast of microbes (residing within an ‘Adoption Center’ on the project website) that live in the dark ocean and asked to select and virtually ‘adopt’ a microbe. A new educational activity was offered each week to encourage learning about microbiology, using the adopted microbe as a focal point. Activities included reading information and asking questions about the adopted microbes (with subsequent responses from shipboard scientists), writing haiku about the adopted microbes, making balloon and fabric models of the adopted microbes, answering math questions related to the study of microbes in the ocean, growing cultures of microbes, and examining the gases produced by microbes. In addition, the website featured regular text, photo and video updates about the science of the expedition using a toy microbe as narrator, as well as stories written by shipboard scientists from the perspective of deep ocean microbes accompanied by watercolor illustrations prepared by a shipboard artist. Assessment methods for evaluating the effectiveness of the Adopt a Microbe project included participant feedback via email and online surveys, website traffic monitoring, and online video viewing rates. Quantitative metrics suggest that the “Adope A Microbe” project was successful in reaching target audiences and helping to encourage and maintain interest in topics related to IODP Expedition 327. The “Adopt A Microbe” project mdel can be adapted for future oceanographic expeditions to help connect the public at large to cutting-edge, exploratory research and for engaging students in active learning.

JR Live: Lessons Learned from Ship-to-Shore Interactions with the JOIDES Resolution

NASA Astrophysics Data System (ADS)

Cooper, S. K.

2016-02-01

Live ship-to-shore events have been conducted regularly from the International Ocean Discovery Program (IODP) research vessel JOIDES Resolution since 2009. These 45-minute events have reached thousands of students, educators and members of the general public with the JR's cutting edge science and technology and the excitement of discovery, science process and careers. Conducted by trained on-board Education/Outreach Officers on board the JR's two-month expeditions, the programs vary over time and have evolved with available technology. Each event incorporates collaboration between the Education Officer, scientists who are a part of the expedition science party, and requests from shore-side audiences. These collaborations have been successful in igniting interest among students and educators, providing scientists with outreach experiences and in meeting education standards and goals. Over the past six years, many lessons have been learned about procedures, technology, content, follow-up and impact. This session will share some of these lessons, identify opportunities for collaboration and engagement, and explore growth opportunities and directions.

Studies on thermophysical properties at New Jersey Shallow Shelf (IODP Expedition 313)

NASA Astrophysics Data System (ADS)

Fehr, A.; Pechnig, R.; Inwood, J.; LOFI, J.; Bosch, F. P.; Clauser, C.

2011-12-01

The IODP drilling expedition 313 New Jersey Shallow Shelf was proposed for obtaining deep sub-seafloor samples and downhole logging measurements in the crucial inner shelf region.The inner to central shelf off-shore New Jersey is an ideal location for studying the history of sea-level changes and its relationship to sequence stratigraphy and onshore/offshore groundwater flows. The region features rapid depositional rates, tectonic stability, and well-preserved, cosmopolitan age control fossils suitable for characterizing the sediments of this margin throughout the time interval of interest. Past sea-level rise and fall is documented in sedimentary layers deposited during Earth's history. In addition, the inner shelf is characterised by relatively fresh pore water intervals alternating vertically with saltier intervals (Mountain et al., 2010). Therefore, three boreholes were drilled in the so-called New Jersey/Mid-Atlantic transect during IODP Expedition 313 New Jersey Shallow Shelf. Numerous questions have arisen concerning the age and origin of the brackish waters recovered offshore at depth. Here we present an analysis of thermophysical properties to be used as input parameters in constructing numerical models for future groundwater flow simulations. Our study is based mainly on Nuclear Magnetic Resonance (NMR) measurements for inferring porosity and permeability, and thermal conductivity. We performed NMR measurements on samples from boreholes M0027A, M0028A and M0029A and thermal conductivity measurements on the whole round cores prior to the Onshore Party. These results are compared with data from alternative laboratory measurements and with petrophysical properties inferred from downhole logging data.

Did the onset of high amplitude glacio-eustatic cycles trigger mass-transport processes on the Northwest Shelf of Australia? Insights from IODP expedition 356

NASA Astrophysics Data System (ADS)

Gallagher, S. J.; McCaffrey, J.; Wallace, M. W.; Keep, M.; Fulthorpe, C.; Bogus, K.; McHugh, C.

2017-12-01

Mass-transport processes on continental margins may have catastrophic consequences, causing tsunamis, major rock falls and avalanches and can destroy offshore hydrocarbon installations. Mass-transport deposits (MTD's) with volumes 17 to >162 km3 are common along the northwest margin of Australia. One of the largest is the Gorgon slide which is offshore from Barrow Island with a minimum volume of 250 km3. Age estimates for slides on the Northwest Shelf are variable and range from Miocene to Recent (Gorgon MTD), late Pliocene to Recent (Thebe/Bonaventure MTD's) and Pleistocene to Recent. This age uncertainty is related to a lack of cored sections through these slides and relies on pre-existing ages and correlations from poorly dated sections (usually industry well sections with minimal samples in the upper 500 m) distal from the MTD's. Therefore, the age, origin and history of these MTD's is not well known. A recent International Ocean Discovery Program Expedition (IODP Expedition 356) to the region obtained a series of continuous cores from the upper 600m to 1.1 km of the Northern Carnarvon and Roebuck Basins. Four sites were cored adjacent to hydrocarbon wells; West Tryal Rocks-2 (Site U1461), Fisher-1 (Site U1462), Picard-1 (Site U1463) and Minilya-1 (Site U1464). Site U1461 yielded 100% core recovery through the Gorgon Slide. Preliminary data from this section suggests that it is relatively young (<1 Ma) with ongoing activity from 0.5 Ma continuing to today. We suggest neotectonism combined with the onset of high amplitude glacio-eustatic cycles may have been triggering factors for this slide.

Quantifying K, U, and Th contents of marine sediments using shipboard natural gamma radiation spectra measured on DV JOIDES Resolution

NASA Astrophysics Data System (ADS)

De Vleeschouwer, David; Dunlea, Ann G.; Auer, Gerald; Anderson, Chloe H.; Brumsack, Hans; de Loach, Aaron; Gurnis, Michael; Huh, Youngsook; Ishiwa, Takeshige; Jang, Kwangchul; Kominz, Michelle A.; März, Christian; Schnetger, Bernhard; Murray, Richard W.; Pälike, Heiko

2017-03-01

During International Ocean Discovery Program (IODP) expeditions, shipboard-generated data provide the first insights into the cored sequences. The natural gamma radiation (NGR) of the recovered material, for example, is routinely measured on the ocean drilling research vessel DV JOIDES Resolution. At present, only total NGR counts are readily available as shipboard data, although full NGR spectra (counts as a function of gamma-ray energy level) are produced and archived. These spectra contain unexploited information, as one can estimate the sedimentary contents of potassium (K), thorium (Th), and uranium (U) from the characteristic gamma-ray energies of isotopes in the 40K, 232Th, and 238U radioactive decay series. Dunlea et al. (2013) quantified K, Th, and U contents in sediment from the South Pacific Gyre by integrating counts over specific energy levels of the NGR spectrum. However, the algorithm used in their study is unavailable to the wider scientific community due to commercial proprietary reasons. Here, we present a new MATLAB algorithm for the quantification of NGR spectra that is transparent and accessible to future NGR users. We demonstrate the algorithm's performance by comparing its results to shore-based inductively coupled plasma-mass spectrometry (ICP-MS), inductively coupled plasma-emission spectrometry (ICP-ES), and quantitative wavelength-dispersive X-ray fluorescence (XRF) analyses. Samples for these comparisons come from eleven sites (U1341, U1343, U1366-U1369, U1414, U1428-U1430, and U1463) cored in two oceans during five expeditions. In short, our algorithm rapidly produces detailed high-quality information on sediment properties during IODP expeditions at no extra cost.

Organic Matter Contents and Paleoproductivity Variation Within Late Pleistocene Japan Sea/East Sea Sediments: Results from IODP Expedition 346

NASA Astrophysics Data System (ADS)

Black, H. D.; Anderson, W. T., Jr.

2017-12-01

Inorganic and organic matter concentrations as well as the stable isotopes of nitrogen and organic carbon are presented for continuous sedimentary sequences collected during Integrated Ocean Drilling Program (IODP) Expedition 346 in the Japan Sea/East Sea in 2013. During major glacioeustatic sea level changes, the paleoceanographic conditions within the Japan Sea/East Sea widely vary due to the shallow, narrow straights connecting the sea to surrounding waters limiting an influx of oceanic currents. During glacial sea level low-stands the sea can be nearly isolated, creating a highly-stratified water column and hypoxic to anoxic bottom water conditions. Meanwhile during sea level high-stands, the Tsushima Warm Current (TWC) flows into the sea bringing warmer, nutrient-rich inputs, leading to vertical mixing and oxic conditions. This study aims to better understand the role of orbital cycling within the organic matter and stable isotope contents of these Late Pleistocene sediments. A total of 192 samples were analyzed each for %CaCO3, %TOC, δ13C, %N, and δ15N from two Expedition 346 sampling sites (U1426 and U1427) during the last 430,000 years and statistical analyses were completed using wavelet and time series analyses. Carbonate concentration ranges from 0-44.3%, total organic carbon 0.2 to 6.4%, δ13C -25.8 to -19.6‰, %N 0.04 to 0.4%, and δ15N 3.8 to 13.1‰. These results are well correlated with b* color values of the sediment and generally show increased productivity during interglacial periods, likely through increased vertical mixing and deepwater ventilation, when compared to glacial periods within the Japan Sea/East Sea when the sea may be partially isolated.

On the 40Ar/39Ar Dating of Low-Potassium Ocean Crust Basalt from IODP Expedition 349, South China Sea

NASA Astrophysics Data System (ADS)

Koppers, A. A. P.

2014-12-01

Accurate age dates for the basement rocks in the South China Sea (SCS) basins were lacking before the execution of International Ocean Discovery Program (IODP) Expedition 349 in early 2014. This left a large margin of error in estimated opening ages for the SCS and rendered various hypotheses regarding its opening mechanism and history untested, hampering our understanding of East Asian tectonic and paleoenvironmental evolution. Therefore, high-precision 40Ar/39Ar age dating lies at the heart of Expedition 349, which in particular aimed to determine the timing of the start and cessation of seafloor spreading in the SCS. In addition, the recovery of a complete seamount apron section at Site U1431 allows 40Ar/39Ar dating of abundantly present plagioclase and biotite crystals to help establish a detailed chronology of the sedimentary and volcaniclastic sequences cored. Here we present the first 40Ar/39Ar incremental heating ages on the low-potassium (~0.1-0.2 wt% K2O) and the least altered (loss on ignition < 1.5%) mid-ocean ridge basalt (MORB) from the SCS. Plagioclase and groundmass samples were prepared using conventional mineral separation techniques, acid-leaching and hand-picking. Analyses were carried out using a new ARGUS-VI multi-collector noble gas mass spectrometer. Ages are expected to have precisions ranging between 0.1-0.3 Ma (2σ), which will allow us to precisely and accurately date the final emplacement of basalts at Sites U1431, U1433 and U1434 in the SCS basin, just prior to the cessation of spreading as all sites were slightly offset from the relict spreading center.

EarthLabs Climate Detectives: Using the Science, Data, and Technology of IODP Expedition 341 to Investigate the Earth's Past Climate

NASA Astrophysics Data System (ADS)

Mote, A. S.; Lockwood, J.; Ellins, K. K.; Haddad, N.; Ledley, T. S.; Lynds, S. E.; McNeal, K.; Libarkin, J. C.

2014-12-01

EarthLabs, an exemplary series of lab-based climate science learning modules, is a model for high school Earth Science lab courses. Each module includes a variety of learning activities that allow students to explore the Earth's complex and dynamic climate history. The most recent module, Climate Detectives, uses data from IODP Expedition 341, which traveled to the Gulf of Alaska during the summer of 2013 to study past climate, sedimentation, and tectonics along the continental margin. At the onset of Climate Detectives, students are presented with a challenge engaging them to investigate how the Earth's climate has changed since the Miocene in southern Alaska. To complete this challenge, students join Exp. 341 to collect and examine sediments collected from beneath the seafloor. The two-week module consists of six labs that provide students with the content and skills needed to solve this climate mystery. Students discover how an international team collaborates to examine a scientific problem with the IODP, compete in an engineering design challenge to learn about scientific ocean drilling, and learn about how different types of proxy data are used to detect changes in Earth's climate. The NGSS Science and Engineering Practices are woven into the culminating activity, giving students the opportunity to think and act like scientists as they investigate the following questions: 1) How have environmental conditions in in the Gulf of Alaska changed during the time when the sediments in core U1417 were deposited? (2) What does the occurrence of different types of diatoms and their abundance reveal about the timing of the cycles of glacial advance and retreat? (3) What timeline is represented by the section of core? (4) How do results from the Gulf of Alaska compare with the global record of glaciations during this period based on oxygen isotopes proxies? Developed by educators in collaboration with Expedition 341 scientists, Climate Detectives is a strong example of how learners can engage in authentic research experiences using real data in the secondary science classroom. In this session you will receive a brief overview of the EarthLabs project, learn more about IODP Expedition 341, and see some of the resources that the module makes available to students to help them analyze the data.

Borehole instability analysis for IODP Site C0002 of the NanTroSEIZE Project, Nankai Trough subduction zone

NASA Astrophysics Data System (ADS)

Wu, H.; Kido, Y. N.; Kinoshita, M.; Saito, S.

2013-12-01

Wellbore instability is a major challenge for the engineer evaluating borehole and formation conditions. Instability is especially important to understand in areas with high stress variations, significant structure anisotropy, or pre-existing fracture systems. Borehole (in)stability is influenced by rock strength, structural properties, and near-field principal stresses. During drilling, the borehole conditions also impact borehole integrity. Factors that we can measure in the borehole during with logging while drilling (LWD) to understand these conditions include mud weight, mud loss, ROP (Rate of Penetration), RPM (Rotation Per Minute), WOB (Weight on Bit), and TORQ (Power swivel torque value). We conducted borehole instability analysis for Site C0002 of the Nankai Trough transect based on riser and riserless drilling during IODP Expedition 338. The borehole shape, determined from LWD resistivity images, indicates that most of drilling occurred in stable environments, however, in a few instances the bottom hole assembly became stuck. We used our stress profile model to evaluate the mud weight required to drill a stable borehole for the estimated rock strength and physical properties. Based on our analysis, we interpret that borehole instability during IODP Expedition 338 may have been caused by weak bedding plane and fluid overpressure state. Future work with this model will investigate the roles of these conditions.

Detachment Faulting, Serpentinization, Fluids and Life: Preliminary Results of IODP Expedition 357 (Atlantis Massif, MAR 30°N)

NASA Astrophysics Data System (ADS)

Fruh-Green, G. L.; Orcutt, B.; Green, S.; Cotterill, C.

2016-12-01

We present an overview of IODP Expedition 357, which successfully used two seabed rock drills to core 17 shallow holes at 9 sites across Atlantis Massif (Mid-Atlantic Ridge 30°N). A major goal of this expedition is to investigate serpentinization processes and microbial activity in the shallow subsurface of highly altered ultramafic and mafic sequences that have been uplifted to the seafloor along a major detachment fault zone. More than 57 m of core were recovered, with borehole penetration ranging from 1.3 to 16.4 meters below seafloor, and core recovery as high as 75% of total penetration. The cores show highly heterogeneous rock type, bulk rock chemistry and alteration that reflect multiple phases of magmatism and fluid-rock interaction within the detachment fault zone. In cores along an E-W transect of the southern wall, recovered mantle peridotites are locally intruded by gabbroic and doleritic dikes and veins. The proportion of mafic rocks are volumetrically less than the amount of mafic rocks recovered previously in the central dome at IODP Site U1309, suggesting a lower degree of melt infiltration into mantle peridotite at the ridge-transform intersection. New technologies were developed and successfully applied for the first time: (1) an in-situ sensor package and water sampling system on each seabed drill measured real-time variations in dissolved methane, oxygen, pH, oxidation reduction potential, temperature, and conductivity during drilling and took water samples after drilling; (2) a borehole plug system to seal the boreholes was successfully deployed at two sites to allow access for future sampling; and (3) delivery of chemical tracers into the drilling fluids for contamination testing. We will provide an overview of the drilling strategy and preliminary results of Expedition 357, and highlight the role of serpentinization in sustaining microbial communities in a region of active serpentinization and low temperature hydrothermal alteration.

Linking downhole logging data with geology and drilling /coring operations - Example from Chicxulub Expedition 364.

NASA Astrophysics Data System (ADS)

Lofi, Johanna; Smith, Dave; Delahunty, Chris; Le Ber, Erwan; Mellet, Claire; Brun, Laurent; Henry, Gilles; Paris, Jehanne

2017-04-01

Expedition 364 was a joint IODP/ICDP mission specific platform expedition to explore the Chicxulub impact crater buried below the Yucatán continental shelf. In April and May 2016, our Expedition drilled a single borehole at Site M0077A into the crater's peak ring. It allowed recovering 303 excellent quality cores from 505.7 to 1334.7 meters below sea floor and acquiring more than 5.8 km of high resolution open hole logs. Downhole logs are rapidly collected, continuous with depth, and measured in situ; these data are classically interpreted in terms of stratigraphy, lithology, porosity, fluid content, geochemical composition and structure of the formation drilled. Downhole logs also allow assessing borehole quality (eg. shape and trajectory), and can provide assistance for decision support during drilling operations. In this work, Expedition 364 downhole logs are used to improve our understanding of the drilling/coring operation history. Differentiating between natural geological features and borehole artifacts are also critical for data quality assessment. The set of downhole geophysical tools used during Expedition 364 was constrained by the scientific objectives, drilling/coring technique, hole conditions and temperature at the drill site. Wireline logging data were acquired with slimline tools in three logging phases at intervals 0-503, 506-699 and 700-1334 mbsf. Logs were recorded either with standalone logging tools or, for the first time in IODP, with stackable slimline tools. Log data included total gamma radiation, sonic velocity, acoustic and optical borehole images, resistivity, conductivity, magnetic susceptibility, caliper and borehole fluid parameters. The majority of measurements were performed in open borehole conditions. During the drilling operations some problems were encountered directly linked to the geology of the drilled formation. For example, two zones of mud circulation losses correlate in depth with the presence of karst cavities or open faults, as evidenced from borehole wall images. Both form conduits probably open at a large scale as suggested by associated anomalies in the borehole fluid temperature profiles. When coring the basement, pieces of metal trapped outside the drill bit apparently led to an increase of the borehole tilt as well as to an enlargement of the hole, although this later remained sub-circular. In the post impact carbonates, 6-7 m long apparent cyclic oscillations in the magnetic field coupled to a spiral shape trajectory of the same wavelength suggest drilling induced artifacts and formation re-magnetization. Acknowledgements: Expedition 364 was funded by IODP with co-funding from ICDP and implemented by ECORD, with contributions and logistical support from the Yucatán state government and Universidad Nacional Autónoma de México. Drilling Services were provided by DOSECC Exploration Services. The downhole logging program was coordinated by EPC, as part of ESO. Expedition 364 Scientists: S. Gulick, J.V. Morgan, E. Chenot, G. Christeson, P. Claeys, C. Cockell, M.J. L. Coolen, L. Ferrière, C. Gebhardt, K. Goto, H. Jones, D.A. Kring, J. Lofi, X. Long, C. Lowery, C. Mellett, R. Ocampo-Torres, L. Perez-Cruz, A. Pickersgill, M. Poelchau, A. Rae, C. Rasmussen, M. Rebolledo-Vieyra, U. Riller, H. Sato, J. Smit, S. Tikoo, N. Tomioka, M. Whalen, A. Wittmann, J. Urrutia-Fucugauchi, K.E. Yamaguchi, W. Zylberman.

Upward extension of the Nankai accretionary prism megasplay fault into slope basin strata. Insights from drilling at IODP Expedition 338 Site C0022

NASA Astrophysics Data System (ADS)

Fabbri, O.; Oohashi, K.; Kanagawa, K.; Yamaguchi, A.

2013-12-01

Megasplay faults have been recognized on seismic reflection profiles across several convergent margins in the world. Understanding the behavior of these faults during large to very large inter-plate earthquakes is a major challenge in assessing strong-motion and tsunami hazards at or near subduction zones. One of the goals of the IODP NanTroSEIZE project is to drill across and to obtain data from the megasplay fault crossing the Nankai accretionary prism off Kii peninsula (Kumano transect), SW Japan. This fault is considered to have been activated during the 1944 Tonankai earthquake (Baba et al., 2006 ; Moore et al., 2007). Drilling and coring during IODP Expedition 316 (Expedition 316 Scientists, 2009) showed that the megasplay fault at 300 mbsf at Site C0004 consists in a 60 m thick package of fractured and brecciated rocks. Combined analysis of 3D reflection data in the vicinity of Site C0004 and core data from sites C0004 and C0008 (Strasser et al., 2009 ; Kimura et al., 2011) suggest that the lower boundary of the megasplay fault ceased activity at about 1.55 Ma while its upper boundary has remained active since about 1.95 Ma and probably 1.24 Ma. In order to determine whether the megasplay fault upper boundary crosscuts slope sediments or is sealed by them, drilling at IODP Site C0022 was carried out during Expedition 338. Two 420 m deep holes were drilled: C0022A (LWD) and C0022B (coring). At Hole C0022A, LWD resistivity images show that the 85-105.5 mbsf interval is fractured and extends above and below a ca. 1 m thick interval characterized by a low resistivity value at 100-101 mbsf. Structures observed in cores from Hole C0022B confirm LWD data. While gently dipping elsewhere, bedding in the 73-146 mbsf interval is steep, commonly exceeding 30°. This bedding dip increase may be a consequence of fault activity (folding ?). Though the low-resistivity interval at 100-101 mbsf could not be sampled at Hole C0022B (no recovery between 95.5 and 99.5 mbsf), cores immediately from above this interval show three ca. 2 cm thick zones of claystone characterized by a marked planar fabric bearing faint striations raking at about 90°. Preliminary biostratigraphic dating in Hole C0022B indicate age reversals at 80.5, 137.5 and 145.5 mbsf, suggesting reverse offset bringing older strata over younger strata. Drilling at IODP Site C0022 confirms that a branch of the megasplay fault previously cored at Expedition 316 Site C0004 extends upwards and southeastwards. The core zone of this branch lies at about 100 mbsf and is about 1 m thick. The presence of weakly foliated claystone suggests aseismic motion immediately above the core zone. The lack of samples from the core zone prevents to determine whether motion was aseismic or not.

Geophysical Signatures of cold vents on the northern Cascadia margin

NASA Astrophysics Data System (ADS)

Riedel, M.; Paull, C. K.; Spence, G.; Hyndman, R. D.; Caress, D. W.; Thomas, H.; Lundsten, E.; Ussler, W.; Schwalenberg, K.

2009-12-01

The accretionary prism of the northern Cascadia margin is a classic gas hydrate research area. Ocean Drilling Program Leg 146 and Integrated Ocean Drilling Program (IODP) Expedition 311 documented that gas hydrate is widely distributed across the margin. In recent years an increased research focus has been on cold vents, where methane gas is actively released. Two recent expeditions funded by the Monterey Bay Aquarium Research Institute (MBARI) were conducted in the area of IODP Sites U1327 and U1328. An autonomous underwater vehicle (AUV) was used to map the seafloor bathymetry followed by dives with the ROV Doc Ricketts for ground truth information of various seafloor morphological features identified. The two cruises revealed many new seafloor features indicative of methane venting that were previously unknown. Bullseye Vent (BV) has been extensively studied using seismic imaging, piston coring, heat-flow, controlled-source EM, and deep drilling. BV is seismically defined by a circular wipe-out zone but the new AUV data show that BV is rather an elongated depression. BV is associated with a shoaling in the BSR, but lacks evidence for the existence of an underlying fault in the previous data. Although a massive gas-hydrate plug was encountered within the top 40 mbsf in the IODP holes, the ROV observations only revealed some platy methane derived carbonate outcrops at the outer-most rim of the depressions, a few beds of Vesicomya clams, and no observed gas vents, which together do not indicate that BV is especially active now. Further northeast of BV, but along the same trend, active gas venting was found associated with seafloor blistering and bacterial mats suggesting that there is an underlying fault system providing a fluid flow conduit. The newly discovered vent area has few seismic line crossings; however the available seismic data surprisingly are not associated with wipe-out zones. Another prominent fault-related gas vent also was investigated during the two MBARI expeditions in 2009 (Spinnaker Vent, SV). Seismic profiles over SV show blanking and a slight uplift of the BSR that underlies the vent-area. The seafloor morphological expressions (trending over ~400 m) are similar to the elongated series of depressions seen at BV, but SV overall appears more active and younger due to the presence of widespread chemosynthetic communities, methane bubbling, massive outcrops of methane-derived carbonate as well as seafloor gas-hydrate bearing mounds. The seafloor features at SV all follow a fault trend that is clearly seen on the AUV bathymetry map, as also suggested by the earlier seismic data. Together the new MBARI expeditions and previous studies show that the area investigated on the N. Cascadia margin is dominated by fluid escape features. At least 12 cold vents (7 with bubble-plumes) are now identified within an area of ~10 km2 making a re-evaluation of the methane hydrate and associated underlying fluid-flow regimes an important focus of future studies.

Scientific Drilling in the Arctic Ocean: A challenge for the next decades

NASA Astrophysics Data System (ADS)

Stein, R.; Coakley, B.

2009-04-01

Although major progress in Arctic Ocean research has been made during the last decades, the knowledge of its short- and long-term paleoceanographic and paleoclimatic history as well as its plate-tectonic evolution is much behind that from the other world's oceans. That means - despite the importance of the Arctic in the climate system - the data base we have from this area is still very weak, and large parts of the climate history have not been recovered at all in sedimentary sections. This lack of knowledge is mainly caused by the major technological/ logistic problems in reaching this permanently ice-covered region with normal research vessels and in retrieving long and undisturbed sediment cores. With the successful completion of IODP Expedition 302 ("Arctic Coring Expedition" - ACEX), the first Mission Specific Platform (MSP) expedition within the Integrated Ocean Drilling Program - IODP, a new era in Arctic research has begun. For the first time, a scientific drilling in the permanently ice-covered Arctic Ocean was carried out, penetrating about 430 meters of Quaternary, Neogene, Paleogene and Campanian sediment on the crest of Lomonosov Ridge close to the North Pole. The success of ACEX has certainly opened the door for further scientific drilling in the Arctic Ocean, and will frame the next round of questions to be answered from new drill holes to be taken during the next decades. In order to discuss and plan the future of scientific drilling in the Arctic Ocean, an international workshop was held at the Alfred Wegener Institute (AWI) in Bremerhaven/Germany, (Nov 03-05, 2008; convenors: Bernard Coakley/University of Alaska Fairbanks and Ruediger Stein/AWI Bremerhaven). About 95 scientists from Europe, US, Canada, Russia, Japan, and Korea, and observers from oil companies participated in the workshop. Funding of the workshop was provided by the Consortium for Ocean Leadership (US), the European Science Foundation, the Arctic Ocean Sciences Board, and the Nansen Arctic Drilling Program as well as by sponsorships from British Petroleum, ConocoPhillips, ExxonMobil, Norwegian Petroleum Directorate, StatoilHydro, and Shell International. The major targets of the workshop were: (1) to bring together an international group of Arctic scientists, young scientists and ocean drilling scientists to learn and exchange ideas, experience and enthusiasm about the Arctic Ocean; (2) to develop a scientific drilling strategy to investigate the tectonic and paleoceanographic history of the Arctic Ocean and its role in influencing the global climate system; (3) to summarize the technical needs, opportunities, and limitations of drilling in the Arctic; (4) to define scientific and drilling targets for specific IODP-type campaigns in Arctic Ocean key areas to be finalized in the development of drilling proposals. Following overview presentations about the history of the Arctic Ocean, legacy of high-latitude ocean drilling, existing site-survey database, technical needs for high-latitude drilling, possibilities of collaboration with industry, and the process of developing ocean-drilling legs through IODP, the main part of the workshop was spent in thematic and regional break-out groups discussing the particular questions to be addressed by drilling and the particular targets for Arctic scientific drilling. Within the working groups, key scientific questions (related to the overall themes paleoceanography, tectonic evolution, petrology/geochemistry of basement, and gas hydrates) and strategies for reaching the overall goals were discussed and - as one of the main results - core groups for further developing drilling proposals were formed. Based on discussions at this workshop, approximately ten new pre-proposals are planned to be submitted to IODP for the April 01- 2009 deadline. We hope that the development of new scientific objectives through the pre-proposal process will help reshape plans for scientific ocean drilling beyond 2013 and direct the program north towards these critical priorities and advance exploration of the Arctic.

In situ rock strength and far field stress in the Nankai accretionary complex: Integration of downhole data from multiple wells

NASA Astrophysics Data System (ADS)

Huffman, K. A.; Saffer, D. M.

2014-12-01

Knowing the magnitude of tectonic stress and rock strength at seismically active margins is important towards understanding fault strength and failure mechanics, yet both are difficult to measure in situ. Recent work at subduction margins, including Integrated Ocean Drilling Program (IODP) Nankai Trough Subduction Zone Experiment (NanTroSEIZE) drillsites, uses the width of compressional wellbore breakouts (BO), which depends on far field stress conditions, rock strength, and borehole annular pressure (APRS), to estimate the magnitude of horizontal principal stresses (SHmax and Shmin); estimates are problematic due to uncertainty in rock strength (unconfined compressive strength/UCS- for which direct measurements are scarce) and rheology that govern stress distribution at the wellbore. We conduct a novel case study at IODP Site C0002, where a hole was drilled twice with different boundary conditions, providing an opportunity to define in situ stress and strength from field data. Site C0002 is the main deep riser borehole for NanTroSEIZE, located near the seaward edge of the Kumano Basin above the seismogenic plate boundary, ~30 km from the trench. Several boreholes were drilled at the site. During IODP Expedition 314 in 2007, Hole C0002A was drilled with a suite of logging while drilling (LWD) tools to 1401 mbsf in a riserless mode. Hole C0002F, ~70 m away, was drilled to 862 mbsf in riserless mode during Exp. 326 in 2010 and deepened to 2005 mbsf in a riser mode during Expedition 338 in 2012-2013. Increased APRS achieved by riser drilling stabilizes the borehole and suppresses BO, consistent with resistivity imaging data from Exp. 314 that document well-developed, continuous BO throughout the borehole, and data from Expedition 338 indicating few BO. We use a semi-Newtonian approach to solve for stress and UCS consistent with the observed BO width and measured APRS in the two holes over the interval from 862-2005 mbsf. Effective SHmax ranges from ~10-30 MPa and indicate a strike-slip or thrust regime. Our results indicate UCS is higher than predicted by empirical relations and a small suite of laboratory tests by as much as 20 MPa. This apparent discrepancy may indicate that the failure criterion, or assumed distribution of stresses around the wellbore in analyses of far field stress, may not be appropriate in this setting.

The first microbiological contamination assessment by deep-sea drilling and coring by the D/V Chikyu at the Iheya North hydrothermal field in the Mid-Okinawa Trough (IODP Expedition 331)

PubMed Central

Yanagawa, Katsunori; Nunoura, Takuro; McAllister, Sean M.; Hirai, Miho; Breuker, Anja; Brandt, Leah; House, Christopher H.; Moyer, Craig L.; Birrien, Jean-Louis; Aoike, Kan; Sunamura, Michinari; Urabe, Tetsuro; Mottl, Michael J.; Takai, Ken

2013-01-01

During the Integrated Ocean Drilling Program (IODP) Expedition 331 at the Iheya North hydrothermal system in the Mid-Okinawa Trough by the D/V Chikyu, we conducted microbiological contamination tests of the drilling and coring operations. The contamination from the drilling mud fluids was assessed using both perfluorocarbon tracers (PFT) and fluorescent microsphere beads. PFT infiltration was detected from the periphery of almost all whole round cores (WRCs). By contrast, fluorescent microspheres were not detected in hydrothermally active core samples, possibly due to thermal decomposition of the microspheres under high-temperature conditions. Microbial contamination from drilling mud fluids to the core interior subsamples was further characterized by molecular-based evaluation. The microbial 16S rRNA gene phylotype compositions in the drilling mud fluids were mainly composed of sequences of Beta- and Gammaproteobacteria, and Bacteroidetes and not archaeal sequences. The phylotypes that displayed more than 97% similarity to the sequences obtained from the drilling mud fluids were defined as possible contaminants in this study and were detected as minor components of the bacterial phylotype compositions in 13 of 37 core samples. The degree of microbiological contamination was consistent with that determined by the PFT and/or microsphere assessments. This study suggests a constructive approach for evaluation and eliminating microbial contamination during riser-less drilling and coring operations by the D/V Chikyu. PMID:24265628

The first microbiological contamination assessment by deep-sea drilling and coring by the D/V Chikyu at the Iheya North hydrothermal field in the Mid-Okinawa Trough (IODP Expedition 331).

PubMed

Yanagawa, Katsunori; Nunoura, Takuro; McAllister, Sean M; Hirai, Miho; Breuker, Anja; Brandt, Leah; House, Christopher H; Moyer, Craig L; Birrien, Jean-Louis; Aoike, Kan; Sunamura, Michinari; Urabe, Tetsuro; Mottl, Michael J; Takai, Ken

2013-01-01

During the Integrated Ocean Drilling Program (IODP) Expedition 331 at the Iheya North hydrothermal system in the Mid-Okinawa Trough by the D/V Chikyu, we conducted microbiological contamination tests of the drilling and coring operations. The contamination from the drilling mud fluids was assessed using both perfluorocarbon tracers (PFT) and fluorescent microsphere beads. PFT infiltration was detected from the periphery of almost all whole round cores (WRCs). By contrast, fluorescent microspheres were not detected in hydrothermally active core samples, possibly due to thermal decomposition of the microspheres under high-temperature conditions. Microbial contamination from drilling mud fluids to the core interior subsamples was further characterized by molecular-based evaluation. The microbial 16S rRNA gene phylotype compositions in the drilling mud fluids were mainly composed of sequences of Beta- and Gammaproteobacteria, and Bacteroidetes and not archaeal sequences. The phylotypes that displayed more than 97% similarity to the sequences obtained from the drilling mud fluids were defined as possible contaminants in this study and were detected as minor components of the bacterial phylotype compositions in 13 of 37 core samples. The degree of microbiological contamination was consistent with that determined by the PFT and/or microsphere assessments. This study suggests a constructive approach for evaluation and eliminating microbial contamination during riser-less drilling and coring operations by the D/V Chikyu.

Quaternary radiolarian biostratigraphy in the subarctic northeastern Pacific (IODP Expedition 341 Site U1417) and synchroneity of bioevents across the North Pacific

NASA Astrophysics Data System (ADS)

Matsuzaki, Kenji M.; Suzuki, Noritoshi

2018-01-01

Expedition 341 of the Integrated Ocean Drilling Program (IODP) retrieved sediment cores spanning the time interval between the Pleistocene and Miocene from the southern Gulf of Alaska. Onboard Pleistocene radiolarian biostratigraphy is hereby refined by increasing the sampling resolution. The 178 core samples from the upper 190 m CCSF-B (Composite Core Depth Scale F-B) of Site U1417 contained faunal elements similar to the northwestern Pacific; for example, the three biozones in the northwestern Pacific (i.e., Eucyrtidium matuyamai, Stylatractus universus and Botryostrobus aquilonaris) were also recognized in the Gulf of Alaska, spanning 1.80-1.13 Ma, 1.13-0.45 Ma, and the last 0.45 Myr, respectively. Based on the age model that we used in this study and the shipboard paleomagnetic reversal events, the first occurrences (FOs) of Amphimelissa setosa and Schizodiscus japonicus in the northeastern Pacific were preliminarily determined to be 1.48 and 1.30 Ma, respectively. The last occurrence (LO) of Eucyrtidium matuyamai and the FO of Lychnocanoma sakaii, both well-established bioevents in the northwestern Pacific, were dated at 0.80 and 1.13 Ma, respectively. The LO of E. matuyamai is a synchronous event at 1.05 ± 0.1 Ma in the North Pacific, while the FOs of A. setosa and S. japonicus at 1.48 and 1.30 Ma, respectively, are significantly older than what has been found elsewhere.

Sediment classification using neural networks: An example from the site-U1344A of IODP Expedition 323 in the Bering Sea

NASA Astrophysics Data System (ADS)

Ojha, Maheswar; Maiti, Saumen

2016-03-01

A novel approach based on the concept of Bayesian neural network (BNN) has been implemented for classifying sediment boundaries using downhole log data obtained during Integrated Ocean Drilling Program (IODP) Expedition 323 in the Bering Sea slope region. The Bayesian framework in conjunction with Markov Chain Monte Carlo (MCMC)/hybrid Monte Carlo (HMC) learning paradigm has been applied to constrain the lithology boundaries using density, density porosity, gamma ray, sonic P-wave velocity and electrical resistivity at the Hole U1344A. We have demonstrated the effectiveness of our supervised classification methodology by comparing our findings with a conventional neural network and a Bayesian neural network optimized by scaled conjugate gradient method (SCG), and tested the robustness of the algorithm in the presence of red noise in the data. The Bayesian results based on the HMC algorithm (BNN.HMC) resolve detailed finer structures at certain depths in addition to main lithology such as silty clay, diatom clayey silt and sandy silt. Our method also recovers the lithology information from a depth ranging between 615 and 655 m Wireline log Matched depth below Sea Floor of no core recovery zone. Our analyses demonstrate that the BNN based approach renders robust means for the classification of complex lithology successions at the Hole U1344A, which could be very useful for other studies and understanding the oceanic crustal inhomogeneity and structural discontinuities.

Revised South China Sea spreading history based on macrostructure analysis of IODP Expedition 349 core samples and geophysical data

NASA Astrophysics Data System (ADS)

Sun, Z.; Ding, W.; Zhao, X.; Qiu, N.; Lin, J.; Li, C.

2017-12-01

In Internaltional Ocean Discovery Program (IODP) Expedition 349, four sites were drilled and cored successfully in the South China Sea (SCS). Three of them are close to the central spreading ridge (Sites U1431, U1433 and U1434), and one (Site U1435) is located on an outer rise,,providingsignificant information on the spreading history of the SCS.In order to constrain the spreading historymore accurately with the core results, we analyzed the identifiable macrostructures (over 300 fractures, veins and slickensides)from all the consolidated samples of these four drill sites. Then we made a retrograde reconstruction of the SCS spreading history with the constraints of the estimated fractures and veins, post-spreading volcanism,seismic interpretation, as well as free-air gravity and magnetic anomaly and topography analysis. Our study indicates that the spreading of the SCS experienced at least one ridge jump event and two events of ridge orientation and spreading direction adjustment, which mademagnetic anomaly orientation, ridge positionand facture zone directionskeep changing in the South China Sea. During the last spreading stage, the spreading direction was north-southward but lasted for a very short time period. The oceanic crust is wider in the eastern SCS and tapers out toward west.Due to the subductionof SCS beneath the Philippine Sea plate, the seafloor began to develop new fractures:the NWW-to EW-trending R' shear faults and the NE-trending P faultsbecame dominant faults and controlled the eruption of post-drift volcanism.

Summary of IODP Expedition 344, CRISP-A2, offshore the Osa Peninsula, Costa Rica

NASA Astrophysics Data System (ADS)

Harris, R. N.; Sakaguchi, A.; Petronotis, K. E.

2013-12-01

The Costa Rica Seismogenesis Project (CRISP) is designed to elucidate the processes that control nucleation and seismic rupture of large earthquakes at erosional subduction zones. The CRISP study area is located offshore the Osa Peninsula where the incoming Cocos Ridge has lifted the seismogenic zone to within reach of scientific drilling. The incoming plate is characterized by low sediment supply, a fast convergence rate, abundant plate interface seismicity, and a change in subducting plate relief along strike. In addition to elucidating processes at erosional convergent margins, this project is complementary to other IODP deep fault drilling projects (e.g., NanTroSEIZE and J-FAST). Expedition 344 (23 October - 11 December, 2012) is the second expedition of CRISP Program A (Integrated Ocean Drilling Program Proposal 537A-Full5) that focused on the shallow lithologic, hydrologic, stress, and thermal conditions that lead to unstable slip in the seismogenic zone. With the exception of not reaching the décollement and the underthrust sediment at the toe site (U1412), Expedition 344 exceeded expectations. Material was recovered from the incoming Cocos plate (Sites U1381 and U1414), the toe of the margin (Site U1412), the mid-slope region (Site U1380), and the upper-slope region (Site U1413). Input sites U1381 and U1414 are characterized by anomalously high heat flow and the flow of fluids. These sites contained abundant ash that will be used to assess the impact of Cocos Ridge subduction on the evolution of the Central American volcanic arc. Although toe Site U1412 did not cross the décollement we did penetrate terrigenous sediments interrupted by a Miocene ooze that may reflect accretion of a frontal prism sliver. Mid-slope Site U1380 yielded a major result in that the upper plate material is not a mélange of oceanic material or the offshore extension of the Caribbean large igneous complex, but forearc basin material consisting of lithic sedimentary units. Upper-slope Site U1413 consists of a terrestrially sourced upper slope sequence consistent with high sediment accumulation rates. Preliminary biostratigraphic and paleomagnetic ages from Sites U1380 and U1413, the midslope and upper slope, respectively, yield sediment accumulation rates between ~290 and 590 m/m.y., an order of magnitude greater than estimated offshore the Nicoya Peninsula.

Launching the Next Generation IODP Site Survey Data Bank

NASA Astrophysics Data System (ADS)

Miller, S. P.; Helly, J.; Clark, D.; Eakins, B.; Sutton, D.; Weatherford, J.; Thatch, G.; Miville, B.; Zelt, B.

2005-12-01

The next generation all-digital Site Survey Data Bank (SSDB) became operational on August 15, 2005 as an online resource for Integrated Ocean Drilling Program (IODP) proponents, reviewers, panels and operations, worldwide. There are currently 123 active proposals for drilling at sites distributed across the globe, involving nearly 1000 proponents from more than 40 countries. The goal is to provide an authoritative, persistent, secure, password-controlled and easily-used home for contributed data objects, as proposals evolve through their life cycle from preliminary phases to planned drilling expeditions. Proposal status can be monitored graphically by proposal number, data type or date. A Java SSDBviewer allows discovery of all proposal data objects, displayed over a basemap of global topography, crustal age or other custom maps. Data can be viewed or downloaded under password control. Webform interfaces assist with the uploading of data and metadata. Thirty four different standard data types are currently supported. The system was designed as a fully functioning digital library, not just a database or a web archive, drawing upon the resources of the SIOExplorer Digital Library project. Blocks of metadata are organized to support discovery and use, as appropriate for each data type. The SSDB has been developed by a UCSD team of researchers and computer scientists at the Scripps Institution of Oceanography and the San Diego Supercomputer Center, under contract with IODP Management International Inc., supported by NSF OCE 0432224.

Preliminary data from IODP Site U1338 of the Pacific Equatorial Age Transect (PEAT IODP Expedition 320/321): a study on the interaction between paleoenvironment and evolution of selected calcareous nannofossil taxa

NASA Astrophysics Data System (ADS)

Raffi, I.; Ciummelli, M.; Backman, J.; Iodp Expedition 320/321 Shipboard Scientific Party

2010-12-01

A continuous Cenozoic sediment record of the paleoequatorial Pacific ocean was recovered during IODP Expedition 320/321 (March-June 2009). The Pacific Equatorial Age Transect (PEAT) includes eight sites (U1331 to U1338), cored above the paleo-position of the equator at successive crustal ages on the Pacific plate, with records from the sediment surface to basement, with basalt aged between 53 to 18 Ma. The present study is focused on IODP Site 1338 that collected a 3-18 Ma segment of the PEAT equatorial megasplice. Although the target equatorial interval of Site 1338 was the middle and late Miocene, ~415 m of a complete sedimentary succession from Pleistocene to lower Miocene was recovered. Sediments are nannofossil ooze and chalk with varying concentrations (often relatively high abundances) of biosiliceous components, and show decimeter to meter lithological cycles that possibly reflect changes in production, dissolution, photic zone paleoecology. Ongoing analysis on nannofossil assemblages and selected taxa are providing distribution and abundance data that, combined with geochemical proxies, will unravel the biotic response to different climatic and oceanographic conditions. Biometric analysis and quantitative abundance analysis are used for providing a clear taxonomy of an important Neogene component of the nannofossil assemblages, the genus Discoaster, and for delineating in detail the evolutionary trends within the taxon. Moreover, we will try to relate the evolutionary signal observed in Discoaster lineage to the environmental evolution, namely to significant events such as the carbonate crash (Vincent and Berger, 1985; Lyle, et al., in prep.), the fluctuation and shallowing of the Calcite Compensation Depth (CCD) (Lyle, 2003), and deposition of diatom enriched intervals (Kemp and Baldauf, 1993).

Extracting a Detailed Magnetostratigraphy From Weakly Magnetized, Oligocene to Early Miocene Sediment Drifts Recovered at IODP Site U1406 (Newfoundland Margin, Northwest Atlantic Ocean)

NASA Astrophysics Data System (ADS)

van Peer, Tim E.; Xuan, Chuang; Lippert, Peter C.; Liebrand, Diederik; Agnini, Claudia; Wilson, Paul A.

2017-11-01

Fine-grained magnetic particles in deep-sea sediments often statistically align with the ambient magnetic field during (and shortly after) deposition and can therefore record geomagnetic reversals. Correlation of these reversals to a geomagnetic polarity time scale is an important geochronological tool that facilitates precise stratigraphic correlation and dating of geological records globally. Sediments often carry a remanence strong enough for confident identification of polarity reversals, but in some cases a low signal-to-noise ratio prevents the construction of a reliable and robust magnetostratigraphy. Here we implement a data-filtering protocol, which can be integrated with the UPmag software package, to automatically reduce the maximum angular deviation and statistically mask noisy data and outliers deemed unsuitable for magnetostratigraphic interpretation. This protocol thus extracts a clearer signal from weakly magnetized sediments recovered at Integrated Ocean Drilling Program (IODP) Expedition 342 Site U1406 (Newfoundland margin, northwest Atlantic Ocean). The resulting magnetostratigraphy, in combination with shipboard and shore-based biostratigraphy, provides an age model for the study interval from IODP Site U1406 between Chrons C6Ar and C9n (˜21-27 Ma). We identify rarely observed geomagnetic directional changes within Chrons C6Br, C7r, and C7Ar, and perhaps within Subchron C8n.1n. Our magnetostratigraphy dates three intervals of unusual stratigraphic behavior within the sediment drifts at IODP Site U1406 on the Newfoundland margin. These lithostratigraphic changes are broadly concurrent with the coldest climatic phases of the middle Oligocene to early Miocene and we hypothesize that they reflect changes in bottom water circulation.

Exploring frontiers of the deep biosphere through scientific ocean drilling

NASA Astrophysics Data System (ADS)

Inagaki, F.; D'Hondt, S.; Hinrichs, K. U.

2015-12-01

Since the first deep biosphere-dedicated Ocean Drilling Program (ODP) Leg 201 using the US drill ship JOIDES Resolution in 2002, scientific ocean drilling has offered unique opportunities to expand our knowledge of the nature and extent of the deep biosphere. The latest estimate of the global subseafloor microbial biomass is ~1029cells, accounting for 4 Gt of carbon and ~1% of the Earth's total living biomass. The subseafloor microbial communities are evolutionarily diverse and their metabolic rates are extraordinarily slow. Nevertheless, accumulating activity most likely plays a significant role in elemental cycles over geological time. In 2010, during Integrated Ocean Drilling Program (IODP) Expedition 329, the JOIDES Resolutionexplored the deep biosphere in the open-ocean South Pacific Gyre—the largest oligotrophic province on our planet. During Expedition 329, relatively high concentrations of dissolved oxygen and significantly low biomass of microbial populations were observed in the entire sediment column, indicating that (i) there is no limit to life in open-ocean sediment and (ii) a significant amount of oxygen reaches through the sediment to the upper oceanic crust. This "deep aerobic biosphere" inhabits the sediment throughout up to ~37 percent of the world's oceans. The remaining ~63 percent of the oceans is comprised of higher productivity areas that contain the "deep anaerobic biosphere". In 2012, during IODP Expedition 337, the Japanese drill ship Chikyu explored coal-bearing sediments down to 2,466 meters below the seafloor off the Shimokita Peninsula, Japan. Geochemical and microbiological analyses consistently showed the occurrence of methane-producing communities associated with the coal beds. Cell concentrations in deep sediments were notably lower than those expected from the global regression line, implying that the bottom of the deep biosphere is approached in these beds. Taxonomic composition of the deep coal-bearing communities profoundly differs from those in shallower marine sediments and instead resembles organotrophic communities in forest soils. These findings suggest that the terrigenous microbial ecosystem has been partly retained from the original depositional setting over 20 million years and contributed to deep carbon cycling ever since.

Physical properties of fore-arc basalt and boninite in Izu-Bonin-Mariana forearc recovered by IODP Expedition 352

NASA Astrophysics Data System (ADS)

Honda, M.; Michibayashi, K.; Almeev, R. R.; Christeson, G. L.; Sakuyama, T.; Yamamoto, Y.; Watanabe, T.

2016-12-01

The Izu-Bonin-Mariana (IBM) arc is a typical intraoceanic arc system and is the type locality for subduction initiation. IODP-IBM project is aimed to understand subduction initiation, arc evolution, and continental crust formation. Expedition 352 is one of the IBM projects and that has drilled four sites at the IBM fore-arc. Expedition 352 has successfully recovered fore-arc basalts and boninites related to seafloor spreading during the subduction initiation as well as the earliest arc development. The fore-arc basalts were recovered from two sites (U1440 and U1441) at the deeper trench slope to the east, whereas the boninites were recovered from two sites (U1439 and U1442) at the shallower slope to the west. In this study, we studied textures and physical properties of both the fore-arc basalt and the boninite samples recovered by IODP Expedition 352. The fore-arc basalt samples showed aphyric texture, whereas the boninites showed hyaloclastic, aphyric and porphyritic textures. For the physical properties, we measured density, porosity, P-wave velocity and anisotropy of magnetic susceptibility. P-wave velocities were measured under ordinary and confining pressure. As a result, the densities are in a range between 2 g/cm3 and 3 g/cm3. The porosities are in a range between 5 % and 40 %. The P-wave velocities are in a wide range from 3 km/s to 5.5 km/s and have a positive correlation to the densities. The magnetic susceptibilities showed bimodal distributions so that the physical properties were classified into two groups: a high magnetic susceptibility group (>5×10-3) and a low magnetic susceptibility group (<5×10-3). The high magnetic susceptibility group is almost identical with the fore-arc basalt and boninite samples with the higher correlation trend between the P-wave velocities and the densities, whereas the low magnetic susceptibility group is only the boninite samples with the lower correlation trend between the P-wave velocities and the densities. It suggests that the densities could be related to the occurrence of magnetite in the samples, since the magnetic susceptibilities were remarkably correlated with the relationships between P-wave velocities and densities. In addition, these trends have also been found in the physical properties measured on board during Expedition 351.

Formation MicroScanner (FMS) data and orbital cycle records: preliminary interpretation from the Asian Monsoon IODP Expedition 346

NASA Astrophysics Data System (ADS)

Johanna, Lofi; Grizel, Jimenez Soto; Ryuji, Tada; Murray Richard, W.; Alvarez Zarikian Carlos, A.; Martin, Ziegler

2015-04-01

Recently, IODP Expedition 346 (29 July-27 September 2013) drilled seven sites in in the marginal sea bordered by the Eurasian continent, the Korean Peninsula, and the Japanese Islands, as well as two closely spaced sites in the East China Sea. Expedition 346 was the first scientific drilling expedition ever to focus exclusively on the climate system in this region. During the expedition, the Formation MicroScanner (FMS) downhole logging tool was deployed, providing high-resolution electrical resistivity-based images of borehole walls. Features such as bedding, slump folding and bioturbation can be resolved. Here we analyze FMS image resistivity data collected at Site U1425 that extend back to the Miocene. Analysis allowed the recognition of several FMS intervals, with vertical extension ranging from several tens of centimeters to a few meters, with an apparent cyclicity. These FMS intervals correlate well with other downhole logs (Total Gamma Ray, Uranium, Thorium, Potassium and density). Conductive intervals generally correlate with low gamma ray and low density log values. Conversely, more resistive intervals generally correlate with higher values in the gamma ray and bulk density logs. This relationship can be interpreted in terms of the relative abundance of terrigenous clay/diatoms in the sediment. Clay has high K and Th contents and relatively higher density and lower porosity than higher diatom-rich sediment. Consequently, with the exception of sporadic ash and dolomite layers, conductive intervals in the FMS images tend to reflect intervals enriched in diatoms, whereas resistive intervals reflect relative high-terrigenous clay content. An apparent cyclic nature, with several orders of cycles on the FMS images, is locally clearly observed. The cyclic pattern consists of ~4-8 m thick resistive intervals alternating with conductive intervals, generally correlating in core with laminated (diatomite or carbonate rich) intervals. These conductive intervals often contain higher frequency, smaller scale interbedded layers. The transition between resistive and conductive intervals is marked by an intermediate level of medium conductivity in the FMS images, possibly indicating relative changes in productivity conditions. The FMS images have been interpreted in term of FMS facies (low, medium, high conductivity) and their thickness measured along a 100-m long interval since the late Miocene. Vertical changes in thickness of FMS facies are plotted vs. depth, and we propose an attempt of orbital tuning based on the Site U1425 preliminary age model. In the future, the FMS data will be compared to other proxies measured on cores, and physical and chemical properties of sediments such as color reflectance or XRF data. This research project is undertaken as part of IODP Expedition 346. IODP Expedition 346 Scientists: W.T. Anderson, M.-A. Bassetti, B.J. Brace, S.C. Clemens, G.R. Dickens, A.G. Dunlea, S.J. Gallagher, L.Giosan, M.H. da Costa Gurgel, A.C.G. Henderson, A.E. Holbourn, K. Ikehara, T. Irino, T. Itaki, A. Karasuda, C.W. Kinsley, Y. Kubota, G.S. Lee, K.E. Lee, C.I.C.D. Lopes, M. Saavedra Pellitero, L.C. Peterson, T. Sagawa, R.K. Singh, S. Sugisaki, S. Toucanne, S. Wan, C. Xuan, H. Zheng, C.H. Lee

Arctic Ocean Paleoceanography and Future IODP Drilling

NASA Astrophysics Data System (ADS)

Stein, Ruediger

2015-04-01

Although the Arctic Ocean is a major player in the global climate/earth system, this region is one of the last major physiographic provinces on Earth where the short- and long-term geological history is still poorly known. This lack in knowledge is mainly due to the major technological/logistical problems in operating within the permanently ice-covered Arctic region which makes it difficult to retrieve long and undisturbed sediment cores. Prior to 2004, in the central Arctic Ocean piston and gravity coring was mainly restricted to obtaining near-surface sediments, i.e., only the upper 15 m could be sampled. Thus, all studies were restricted to the late Pliocene/Quaternary time interval, with a few exceptions. These include the four short cores obtained by gravity coring from drifting ice floes over the Alpha Ridge, where older pre-Neogene organic-carbon-rich muds and laminated biosiliceous oozes were sampled. Continuous central Arctic Ocean sedimentary records, allowing a development of chronologic sequences of climate and environmental change through Cenozoic times and a comparison with global climate records, however, were missing prior to the IODP Expedition 302 (Arctic Ocean Coring Expedition - ACEX), the first scientific drilling in the central Arctic Ocean. By studying the unique ACEX sequence, a large number of scientific discoveries that describe previously unknown Arctic paleoenvironments, were obtained during the last decade (for most recent review and references see Stein et al., 2014). While these results from ACEX were unprecedented, key questions related to the climate history of the Arctic Ocean remain unanswered, in part because of poor core recovery, and in part because of the possible presence of a major mid-Cenozoic hiatus or interval of starved sedimentation within the ACEX record. In order to fill this gap in knowledge, international, multidisciplinary expeditions and projects for scientific drilling/coring in the Arctic Ocean are needed. Key areas and approaches for drilling and recovering undisturbed and complete sedimentary sequences are depth transects across the major ocean ridge systems, such as the Lomonosov Ridge. These new detailed climate records spanning time intervals from the (late Cretaceous/)Paleogene Greenhouse world to the Neogene-Quaternary Icehouse world will give new insights into our understanding of the Arctic Ocean within the global climate system and provide an opportunity to test the performance of climate models used to predict future climate change. During the Polarstern Expedition PS87 in August-September 2014, new site survey data including detailed multibeam bathymetry, multi-channel seismic and Parasound profiling as well as geological coring, were obtained on Lomonosov Ridge (Stein, 2015), being the basis for a more precise planning and update for a future IODP drilling campaign. Reference: Stein, R. (Ed.), 2015. Cruise Report of Polarstern Expedition PS87-2014 (Arctic Ocean/Lomonosov Ridge). Reps. Pol. Mar. Res., in press. Stein, R. , Weller, P. , Backman, J. , Brinkhuis, H., Moran, K. , Pälike, H., 2014. Cenozoic Arctic Ocean Climate History: Some highlights from the IODP Arctic Coring Expedition (ACEX). Developments in Marine Geology 7, Elsevier Amsterdam/New York, pp. 259-293.

New Era of Scientific Ocean Drilling

NASA Astrophysics Data System (ADS)

Eguchi, N.; Toczko, S.; Sanada, Y.; Igarashi, C.; Kubo, Y.; Maeda, L.; Sawada, I.; Takase, K.; Kyo, N.

2014-12-01

The D/V Chikyu, committed to scientific ocean drilling since 2007, has completed thirteen IODP expeditions, and Chikyu's enhanced drilling technology gives us the means to reach deep targets, enhanced well logging, deep water riserless drilling, and state of the art laboratory. Chikyu recovered core samples from 2466 meters below sea floor (mbsf) in IODP Exp. 337, and drilled to 3058.5 mbsf in IODP Exp. 348, but these are still not the limit of Chikyu's capability. As deep as these depths are, they are just halfway to the 5200 mbsf plate boundary target for the NanTroSEIZE deep riser borehole. There are several active IODP proposals in the pipeline. Each has scientific targets requiring several thousand meters of penetration below the sea floor. Riser technology is the only way to collect samples and data from that depth. Well logging has been enhanced with the adoption of riser drilling, especially for logging-while-drilling (LWD). LWD has several advantages over wireline logging, and provides more opportunities for continuous measurements even in unstable boreholes. Because of the larger diameter of riser pipes and enhanced borehole stability, Chikyu can use several state-of-the-art downhole tools, e.g. fracture tester, fluid sampling tool, wider borehole imaging, and the latest sonic tools. These new technologies and tools can potentially expand the envelope of scientific ocean drilling. Chikyu gives us access to ultra-deep water riserless drilling. IODP Exp. 343/343T investigating the March 2011 Tohoku Oki Earthquake, explored the toe of the landward slope of the Japan Trench. This expedition reached the plate boundary fault target at more than 800 mbsf in water depths over 6900 m for logging-while-drilling, coring, and observatory installation. This deep-water drilling capability also expands the scientific ocean drilling envelope and provides access to previously unreachable targets. On top of these operational capabilities, Chikyu's onboard laboratory is equipped with state-of-the-art instruments to analyze all science samples. X-ray CT creates non-destructive 3D images of core samples providing high resolution structural detail. The microbiology laboratory offers clean and contamination-free work environments required for microbiological samples.

Composition of Sediment Inputs to the Hikurangi Subduction Margin: A Prelude to IODP Expedition 375

NASA Astrophysics Data System (ADS)

Underwood, M.

2017-12-01

Expedition 375 of the International Ocean Discovery Program is scheduled to begin drilling offshore New Zealand in March 2018. Two sites will be cored seaward of the Hikurangi subduction front (subduction inputs), plus one site at the toe of the accretionary prism, and one site in the forearc above a zone of well-documented slow-slip events. One of the challenges during planning for Expedition 375 has been the total absence of pre-existing compositional data from the region; that lack of basic information impacts such tasks as mixing and analysis of appropriate standards for X-ray diffraction, error analysis, computation of accurate normalization factors, and QA/QC. To help overcome those deficiencies, I analyzed a total of 152 samples from ODP Sites 1123 (Quaternary to Eocene), 1124 (Quaternary to Cretaceous), and 1125 (Quaternary to Miocene), plus piston/gravity-core samples from the repositories at Lamont-Doherty, Oregon State, and NIWA. The results reveal an unusually large range of compositions for the bulk sediments. The relative abundance of total clay minerals ranges from 3 to 64 wt%. Quartz ranges from 0 to 39 wt%. Feldspar ranges from 0 to 40 wt%, and calcite ranges from 0 to 93 wt%. Samples from the Hikurangi Plateau and Chatham Rise are carbonate-rich, with many bordering on almost-pure nannofossil chalk. Hemipelagic muds from the floor of Hikurangi Trough, Ruatoria slide, and the landward slope of the trench are fairly uniform, with averages of 36 wt% total clay minerals, 27 wt% quartz, 24 wt% feldspar, and 13 wt% calcite. Unlike many other subduction zones, this diversity of lithologies will save shipboard scientists from repetitive, mind-numbing descriptions and analyses, and shorebased experiments for frictional properties, permeability, and consolidation will need to pay close attention to the compositional attributes of the specimens. In addition, results from the four IODP boreholes can be interpreted within a broader, regional-scale framework of sediment provenance and dispersal.

Quantifying K, U and Th contents of marine sediments using shipboard natural gamma radiation spectra measured on DV JOIDES Resolution

NASA Astrophysics Data System (ADS)

De Vleeschouwer, David; Dunlea, Ann G.; Auer, Gerald; Anderson, Chloe H.; Brumsack, Hans; de Loach, Aaron; Gurnis, Michael C.; Huh, Youngsook; Ishiwa, Takeshige; Jang, Kwangchul; Kominz, Michelle A.; März, Christian; Schnetger, Bernhard; Murray, Richard W.; Pälike, Heiko; Expedition 356 shipboard scientists, IODP

2017-04-01

During International Ocean Discovery Program (IODP) expeditions, shipboard-generated data provide the first insights into the cored sequences. The natural gamma radiation (NGR) of the recovered material, for example, is routinely measured on the ocean drilling research vessel DV JOIDES Resolution. At present, only total NGR counts are readily available as shipboard data, although full NGR spectra (counts as a function of gamma-ray energy level) are produced and archived. These spectra contain unexploited information, as one can estimate the sedimentary contents of potassium (K), thorium (Th), and uranium (U) from the characteristic gamma-ray energies of isotopes in the 40K, 232Th, and 238U radioactive decay series. Dunlea et al. [2013] quantified K, Th and U contents in sediment from the South Pacific Gyre by integrating counts over specific energy levels of the NGR spectrum. However, the algorithm used in their study is unavailable to the wider scientific community due to commercial proprietary reasons. Here, we present a new MATLAB algorithm for the quantification of NGR spectra that is transparent and accessible to future NGR users. We demonstrate the algorithm's performance by comparing its results to shore-based inductively coupled plasma-mass spectrometry (ICP-MS), inductively coupled plasma-emission spectrometry (ICP-ES), and quantitative wavelength-dispersive X-ray fluorescence (XRF) analyses. Samples for these comparisons come from eleven sites (U1341, U1343, U1366-U1369, U1414, U1428-U1430, U1463) cored in two oceans during five expeditions. In short, our algorithm rapidly produces detailed high-quality information on sediment properties during IODP expeditions at no extra cost. Dunlea, A. G., R. W. Murray, R. N. Harris, M. A. Vasiliev, H. Evans, A. J. Spivack, and S. D'Hondt (2013), Assessment and use of NGR instrumentation on the JOIDES Resolution to quantify U, Th, and K concentrations in marine sediment, Scientific Drilling, 15, 57-63.

IODP Expedition 351 Izu-Bonin-Mariana Arc Origins: Age Model for Site U1438

NASA Astrophysics Data System (ADS)

Morris, A.; Aljahdali, M. H.; Bandini, A. N.; do Monte Guerra, R.; Kender, S.; Maffione, M.

2014-12-01

We report preliminary paleomagnetic and paleontological results from International Ocean Discovery Program (IODP) Expedition 351, which recovered an unprecedented ~1.4 km thick volcaniclastic sedimentary record documenting the initiation and subsequent evolution of the Izu-Bonin-Mariana (IBM) intra-oceanic arc-basin system. Magnetostratigraphic and biostratigraphic constraints provide a high-resolution temporal framework for interpretation of this record.Paleomagnetic analyses of archive half core samples provide a continuous record of the geomagnetic field inclination down to 847 mbsf that allows construction of a detailed site magnetostratigraphy that closely matches the Geomagnetic Polarity Timescale (Gradstein et al., 2012). A total of 87 geomagnetic reversals have been recognized in the studied succession, extending back to ~36 Ma. Despite sporadic microfossil occurrences in parts, calcareous nannofossils, planktonic foraminifera and radiolarians each contribute to the age model for the entire Site. All nannofossil marker species for Oligocene to Eocene Zones NP25 to NP19/20 are recognised. Beneath paleomagnetic control (847-1449 mbsf), foraminifera and radiolarians provide the only age control.The most salient features of the age model are that: (i) average linear sedimentation rates during the Plio-Pleistocene range from 1.4 to 2.2 cm/ka; (ii) there was a reduction in sedimentation rates to 0.25 - 0.5 cm/ka throughout the Miocene; and (iii) sedimentation rates sharply increase again in the Oligocene to Late Eocene to a maximum of ~20 cm/ka. These quantitative constraints closely match (non-quantitative) inferences based on the lithostratigraphy of the site, with fine-grained/coarse-grained sediments dominating in periods with low/high sedimentation rates respectively.

IODP Expedition 351 Izu-Bonin-Mariana Arc Origins: Age model for Site U1438

NASA Astrophysics Data System (ADS)

Morris, Antony; Maffione, Marco; Kender, Sev; Aljahdali, Mohammed; Bandini, Alexandre; Guerra, Rodrigo do Monte

2015-04-01

We report preliminary paleomagnetic and paleontological results from International Ocean Discovery Program (IODP) Expedition 351, which recovered an unprecedented ~1.4 km thick volcaniclastic sedimentary record documenting the initiation and subsequent evolution of the Izu-Bonin-Mariana (IBM) intra-oceanic arc-basin system. Magnetostratigraphic and biostratigraphic constraints provide a high-resolution temporal framework for interpretation of this record. Paleomagnetic analyses of archive half core samples provide a continuous record of the geomagnetic field inclination down to 847 mbsf that allows construction of a detailed site magnetostratigraphy that closely matches the Geomagnetic Polarity Timescale (Gradstein et al., 2012). A total of 87 geomagnetic reversals have been recognized in the studied succession, extending back to ~36 Ma. Despite sporadic microfossil occurrences in parts, calcareous nannofossils, planktonic foraminifera and radiolarians each contribute to the age model for the entire Site. All nannofossil marker species for Oligocene to Eocene Zones NP25 to NP19/20 are recognised. Beneath paleomagnetic control (847-1449 mbsf), foraminifera and radiolarians provide the only age control. The most salient features of the age model are that: (i) average linear sedimentation rates during the Plio-Pleistocene range from 1.4 to 2.2 cm/ka; (ii) there was a reduction in sedimentation rates to 0.25 - 0.5 cm/ka throughout the Miocene; and (iii) sedimentation rates sharply increase again in the Oligocene to Late Eocene to a maximum of ~20 cm/ka. These quantitative constraints closely match (non-quantitative) inferences based on the lithostratigraphy of the site, with fine-grained/coarse-grained sediments dominating in periods with low/high sedimentation rates respectively.

Microstructural analysis and calcite piezometry on hydrothermal veins: Insights into the deformation history of the Cocos Plate at Site U1414 (IODP Expedition 344)

NASA Astrophysics Data System (ADS)

Brandstätter, Jennifer; Kurz, Walter; Rogowitz, Anna

2017-08-01

In this study we present microstructural data from hydrothermal veins in the sedimentary cover and the igneous basement recovered from Hole U1414A, Integrated Ocean Drilling Program (IODP) Expedition 344 (Costa Rica Seismogenesis Project), to constrain deformation mechanism operating in the subducting Cocos Plate. Cathodoluminescence studies, mechanical e-twin piezometry and electron backscatter diffraction (EBSD) analyses of carbonate veins were used to give insights into the deformation conditions and to help to understand the tectonic deformation history of the Cocos Plate offshore Costa Rica. Analyses of microstructures in the sedimentary rocks and in the basalt of the igneous basement reveal brittle deformation, as well as crystal-plastic deformation of the host rock and the vein material. Cathodoluminescence images showed that in the basalt fluid flow and related precipitation occurred over several episodes. The differential stresses, obtained from two different piezometers using the same parameter (twin density), indicate various mean differential stresses of 49 ± 11 and 69 ± 30 MPa and EBSD mapping of calcite veins reveals low-angle subgrain boundaries. Deformation temperatures are restricted to the range from 170°C to 220°C, due to the characteristics of the existing twins and the lack of high-temperature intracrystalline deformation mechanisms (>220°C). The obtained results suggest that deformation occurred over a period associated with changes of ambient temperatures, occurrence of fluids and hydrofracturing, induced differential stresses due to the bending of the plate at the trench, and related seismic activity.

Microstructural analysis and calcite piezometry on hydrothermal veins: Insights into the deformation history of the Cocos Plate at Site U1414 (IODP Expedition 344).

PubMed

Brandstätter, Jennifer; Kurz, Walter; Rogowitz, Anna

2017-08-01

In this study we present microstructural data from hydrothermal veins in the sedimentary cover and the igneous basement recovered from Hole U1414A, Integrated Ocean Drilling Program (IODP) Expedition 344 (Costa Rica Seismogenesis Project), to constrain deformation mechanism operating in the subducting Cocos Plate. Cathodoluminescence studies, mechanical e-twin piezometry and electron backscatter diffraction (EBSD) analyses of carbonate veins were used to give insights into the deformation conditions and to help to understand the tectonic deformation history of the Cocos Plate offshore Costa Rica. Analyses of microstructures in the sedimentary rocks and in the basalt of the igneous basement reveal brittle deformation, as well as crystal-plastic deformation of the host rock and the vein material. Cathodoluminescence images showed that in the basalt fluid flow and related precipitation occurred over several episodes. The differential stresses, obtained from two different piezometers using the same parameter (twin density), indicate various mean differential stresses of 49 ± 11 and 69 ± 30 MPa and EBSD mapping of calcite veins reveals low-angle subgrain boundaries. Deformation temperatures are restricted to the range from 170°C to 220°C, due to the characteristics of the existing twins and the lack of high-temperature intracrystalline deformation mechanisms (>220°C). The obtained results suggest that deformation occurred over a period associated with changes of ambient temperatures, occurrence of fluids and hydrofracturing, induced differential stresses due to the bending of the plate at the trench, and related seismic activity.

IODP Expedition 338: NanTroSEIZE Stage 3: NanTroSEIZE plate boundary deep riser 2

NASA Astrophysics Data System (ADS)

Moore, G. F.; Kanagawa, K.; Strasser, M.; Dugan, B.; Maeda, L.; Toczko, S.

2014-01-01

The Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) is designed to investigate fault mechanics and seismogenesis along a subduction megathrust, with objectives that include characterizing fault slip, strain accumulation, fault and wall rock composition, fault architecture, and state variables throughout an active plate boundary system. Integrated Ocean Drilling Program (IODP) Expedition 338 was planned to extend and case riser Hole C0002F from 856 to 3600 meters below the seafloor (m b.s.f.). Riser operations extended the hole to 2005.5 m b.s.f., collecting logging-while-drilling (LWD) and measurement-while-drilling, mud gas, and cuttings data. Results reveal two lithologic units within the inner wedge of the accretionary prism that are separated by a prominent fault zone at ~ 1640 m b.s.f. Due to damage to the riser during unfavorable winds and strong currents, riser operations were suspended, and Hole C0002F left for re-entry during future riser drilling operations. Contingency riserless operations included coring at the forearc basin site (C0002) and at two slope basin sites (C0021 and C0022), and LWD at one input site (C0012) and at three slope basin sites (C0018, C0021 and C0022). Cores and logs from these sites comprehensively characterize the alteration stage of the oceanic basement input to the subduction zone, the early stage of Kumano Basin evolution, gas hydrates in the forearc basin, and recent activity of the shallow megasplay fault zone system and associated submarine landslides.

Microstructural analysis and calcite piezometry on hydrothermal veins: Insights into the deformation history of the Cocos Plate at Site U1414 (IODP Expedition 344)

PubMed Central

Kurz, Walter; Rogowitz, Anna

2017-01-01

Abstract In this study we present microstructural data from hydrothermal veins in the sedimentary cover and the igneous basement recovered from Hole U1414A, Integrated Ocean Drilling Program (IODP) Expedition 344 (Costa Rica Seismogenesis Project), to constrain deformation mechanism operating in the subducting Cocos Plate. Cathodoluminescence studies, mechanical e‐twin piezometry and electron backscatter diffraction (EBSD) analyses of carbonate veins were used to give insights into the deformation conditions and to help to understand the tectonic deformation history of the Cocos Plate offshore Costa Rica. Analyses of microstructures in the sedimentary rocks and in the basalt of the igneous basement reveal brittle deformation, as well as crystal‐plastic deformation of the host rock and the vein material. Cathodoluminescence images showed that in the basalt fluid flow and related precipitation occurred over several episodes. The differential stresses, obtained from two different piezometers using the same parameter (twin density), indicate various mean differential stresses of 49 ± 11 and 69 ± 30 MPa and EBSD mapping of calcite veins reveals low‐angle subgrain boundaries. Deformation temperatures are restricted to the range from 170°C to 220°C, due to the characteristics of the existing twins and the lack of high‐temperature intracrystalline deformation mechanisms (>220°C). The obtained results suggest that deformation occurred over a period associated with changes of ambient temperatures, occurrence of fluids and hydrofracturing, induced differential stresses due to the bending of the plate at the trench, and related seismic activity. PMID:29081570

Embark students on geosciences expeditions, across the oceans …

NASA Astrophysics Data System (ADS)

Burgio, Marion; Darrieu, Michele; Pointu, Agnes; Maruejol, Patricia; Cooper, Sharon

2017-04-01

As teachers we can live and share a fabulous experience of science and research on the scientific drilling vessels and platforms of IODP-ECORD and JAMSTEC consortiums. ECORD offered us the opportunity to embark on the IODP 359, 360 and 362 expeditions as Education Officers. Our task was to communicate about science with the general public and students from 7 to 25 years-old. In this presentation, we will focus on the 360 expedition, South West Indian Ridge-lower crust and Moho. We explain the three steps of the "teacher at sea" experience from the very first idea to the real pedagogical work during and after the expedition. -Apply, get ready and leave… for two months: From the difficulties you may encounter to the most efficient ways to prepare the pedagogical tasks. -Work, live onboard and get back: We will describe the main activities of the Education officers among the Science party and the way all this can become a highly changing-life experience. -Use data, share and inspire: We will detail some strategies we used to catch the attention of the students. They could participate to "live" science and have a better idea of the job of researcher. Now, we have to inspire others teachers to use our data and pedagogical documents, or to get the opportunity to embark ! What gets out of these crossed experiences is that the quality of the human relationships, and the way the students can get closer to the scientists during the interactions, are the keys to motivate students and give them a new vision of the scientific research.

Source Evolution After Subduction Initiation as Recorded in the Izu-Bonin-Mariana Fore-arc Crust

NASA Astrophysics Data System (ADS)

Shervais, J. W.; Reagan, M. K.; Pearce, J. A.; Shimizu, K.

2015-12-01

Drilling in the Izu-Bonin-Mariana (IBM) fore-arc during IODP Expedition 352 and DSDP Leg 60 recovered consistent stratigraphic sequences of volcanic rocks reminiscent of those found in many ophiolites. The oldest lavas in these sections are "fore-arc basalts" (FAB) with ~51.5 Ma ages. Boninites began eruption approximately 2-3 m.y. later (Ishizuka et al., 2011, EPSL; Reagan et al., 2013, EPSL) and further from the trench. First results from IODP Expedition 352 and preliminary post-cruise data suggest that FAB at Sites U1440 and U1441 were generated by decompression melting during near-trench sea-floor spreading, and that fluids from the subducting slab were not involved in their genesis. Temperatures appear to have been unusually high and pressures of melting appear to have been unusually low compared to mid-ocean ridges. Spreading rates at this time appear to have been robust enough to maintain a stable melt lens. Incompatible trace element abundances are low in FAB compared to even depleted MORB. Nd and Hf Isotopic compositions published before the expedition suggest that FAB were derived from typical MORB source mantle. Thus, their extreme deletion resulted from unusually high degrees of melting immediately after subduction initiation. The oldest boninites from DSDP Site 458 and IODP Sites U1439 and U1442 have relatively high concentrations of fluid-soluble elements, low concentrations of REE, and light depleted REE patterns. Younger boninites, have even lower REE concentrations, but have U-shaped REE patterns. Our first major and trace element compositions for the FAB through boninite sequence suggests that melting pressures and temperatures decreased through time, mantle became more depleted though time, and spreading rates waned during boninite genesis. Subduction zone fluids involved in boninite genesis appear to have been derived from progressively higher temperatures and pressures over time as the subducting slab thermally matured.

Fluid inclusion petrology and microthermometry of the Cocos Ridge hydrothermal system, IODP Expedition 344 (CRISP 2), Site U1414.

PubMed

Brandstätter, Jennifer; Kurz, Walter; Krenn, Kurt; Micheuz, Peter

2016-04-01

In this study, we present new data from microthermometry of fluid inclusions entrapped in hydrothermal veins along the Cocos Ridge from the IODP Expedition 344 Site U1414. The results of our study concern a primary task of IODP Expedition 344 to evaluate fluid/rock interaction linked with the tectonic evolution of the incoming Cocos Plate from the Early Miocene up to recent times. Aqueous, low saline fluids are concentrated within veins from both the Cocos Ridge basalt and the overlying lithified sediments of Unit III. Mineralization and crosscutting relationships give constraints for different vein generations. Isochores from primary, reequilibrated, and secondary fluid inclusions crossed with litho/hydrostatic pressures indicate an anticlockwise PT evolution during vein precipitation and modification by isobaric heating and subsequent cooling at pressures between ∼210 and 350 bar. Internal over and underpressures in the inclusions enabled decrepitation and reequilibration of early inclusions but also modification of vein generations in the Cocos Ridge basalt and in the lithified sediments. We propose that lithification of the sediments was accompanied with a first stage of vein development (VU1 and VC1) that resulted from Galapagos hotspot activity in the Middle Miocene. Heat advection, either related to the Cocos-Nazca spreading center or to hotspot activity closer to the Middle America Trench, led to subsequent vein modification (VC2, VU2/3) related to isobaric heating. The latest mineralization (VC3, VU3) within aragonite and calcite veins and some vesicles of the Cocos Ridge basalt occurred during crustal cooling up to recent times. Fluid inclusion analyses and published isotope data show evidence for communication with deeper sourced, high-temperature hydrothermal fluids within the Cocos Plate. The fluid source of the hydrothermal veins reflects aqueous low saline pore water mixed with invaded seawater.

Fluid inclusion petrology and microthermometry of the Cocos Ridge hydrothermal system, IODP Expedition 344 (CRISP 2), Site U1414

PubMed Central

Brandstätter, Jennifer; Krenn, Kurt; Micheuz, Peter

2016-01-01

Abstract In this study, we present new data from microthermometry of fluid inclusions entrapped in hydrothermal veins along the Cocos Ridge from the IODP Expedition 344 Site U1414. The results of our study concern a primary task of IODP Expedition 344 to evaluate fluid/rock interaction linked with the tectonic evolution of the incoming Cocos Plate from the Early Miocene up to recent times. Aqueous, low saline fluids are concentrated within veins from both the Cocos Ridge basalt and the overlying lithified sediments of Unit III. Mineralization and crosscutting relationships give constraints for different vein generations. Isochores from primary, reequilibrated, and secondary fluid inclusions crossed with litho/hydrostatic pressures indicate an anticlockwise PT evolution during vein precipitation and modification by isobaric heating and subsequent cooling at pressures between ∼210 and 350 bar. Internal over and underpressures in the inclusions enabled decrepitation and reequilibration of early inclusions but also modification of vein generations in the Cocos Ridge basalt and in the lithified sediments. We propose that lithification of the sediments was accompanied with a first stage of vein development (VU1 and VC1) that resulted from Galapagos hotspot activity in the Middle Miocene. Heat advection, either related to the Cocos‐Nazca spreading center or to hotspot activity closer to the Middle America Trench, led to subsequent vein modification (VC2, VU2/3) related to isobaric heating. The latest mineralization (VC3, VU3) within aragonite and calcite veins and some vesicles of the Cocos Ridge basalt occurred during crustal cooling up to recent times. Fluid inclusion analyses and published isotope data show evidence for communication with deeper sourced, high‐temperature hydrothermal fluids within the Cocos Plate. The fluid source of the hydrothermal veins reflects aqueous low saline pore water mixed with invaded seawater. PMID:27570496

IODP Expedition 366 Reveals Widespread Seamount Subduction Effects in the Mariana Forearc

NASA Astrophysics Data System (ADS)

Fryer, P. B.; Wheat, C. G.; Williams, T.

2017-12-01

Numerous studies of the subduction of seamounts at accretionary convergent plate margins show considerable vertical tectonic deformation in the forearc region. This includes embayment of the trench axis, steepening of the inner trench slope, the creation of troughs in the wake of the seamount track beneath the forearc sediment wedge, but hypotheses regarding the seismogenic consequences of these processes are frequently at odds. In the nonaccretionary Mariana convergent plate margin, it is clear that ridges crosscut the entire forearc region in commensurate dimensions with thicker areas of subducting Pacific plate. Furthermore, to-date deep-sea drilling results on ODP Legs 125 and 195 and on IODP Expedition 366 recovered seamount materials from 5 serpentinite mud volcanoes over a 640 km along-strike distance, within 90 km west of the trench axis, and from 13 to 19 km depth to slab. The location of the serpentinite mud volcanoes is always associated with fault lineaments. The faulting creates the conduits for eruption of mixtures of fluids from the subduction channel and fault gouge from both the subduction channel and the forearc lithosphere. Cores from IODP 366 confirm that seamount subduction and deformation is a temporally and spatially pervasive process on the Mariana forearc. The new findings provide windows on a continuum of the evolution of plate and seamount subduction from the trench to nearly 20 km depth within the subduction channel. Cased boreholes were deployed at the summits of three active serpentinite mud volcanoes (Yinazao (Blue Moon), Asùt Tesoro (Big Blue), and Fantangisña (Celestial) Seamounts) during Expedition 366. These, plus the existing borehole observatory at ODP Site 1200C on the active summit of Conical Seamount provide a means to monitor processes of subduction related to serpentinite mud volcanism of the Mariana forearc. Such drilling results and borehole observations impact current paradigms of lithospheric deformation, mass cycling, and physical conditions within the subduction channel.

Chemostratigraphy of Subduction Initiation: Boninite and Forearc Basalt from IODP Expedition 352

NASA Astrophysics Data System (ADS)

Shervais, John; Haugen, Emily; Godard, Marguerite; Ryan, Jeffrey G.; Prytulak, Julie; Li, Hongyan; Chapman, Timothy; Nelson, Wendy R.; Heaton, Daniel E.; Kirchenbaur, Maria; Shimizu, Kenji; Li, Yibing; Whattam, Scott A.; Almeev, Renat; Sakuyama, Tetsuya; Reagan, Mark K.; Pearce, Julian A.

2017-04-01

The Izu-Bonin forearc has been the focus of several recent IODP (International Ocean Discovery Program) expeditions studying the geophysical, petrologic, and chemical response to subduction initiation and its potential relationship to ophiolite genesis. IODP Expedition 352 cored four holes in the Izu-Bonin forearc near Chichi Jima in order to document the petrologic and chemical evolution of nascent subduction zones. Holes U1440 and U1441, drilled closest to the trench, sampled forearc basalt (FAB). U1439 and U1442, drilled stratigraphically up-section and farther from the trench, sampled boninite, high-Mg andesite, and basalt. FAB are characterized by MORB-like compositions, with relatively constant Ti, Zr, and Ti/Zr. In general, more primitive FAB are found in the lower part of the section. In detail, FAB have lower Na, Ti, P, and Zr, lower Ti/V ratios, and are LREE-depleted relative to MORB. Best fit models for the least evolved FAB and a depleted MORB mantle (DMM) source require extraction of 1% melt in the garnet lherzolite field and 19% melt extraction in the spinel lherzolite field (relative to 8-10% melt of DMM to produce MORB). Three types of boninite were found: high silica boninite (HSB), low silica boninite (LSB), and basaltic boninite (BB), as well as high Mg andesites (HMA). HSB, the youngest unit in both U1439 and U1442, is underlain by LSB-BB-HMA lavas, which often occur in mixed magma zones with evolved boninite and basalt. Boninites are distinguished by co-variations in SiO2-MgO and TiO2-MgO, and by Ti/Zr ratios, which increase from HSB through LSB to BB. HSB, LSB and BB define parallel trends in TiO2-MgO space: a low Ti trend represented by LSB and BB, and a lower Ti trend represented by HSB. All of the boninite suite rocks are slightly LREE-rich relative to MORB. LSB and BB have flat REE patterns relative to primitive mantle, whereas HSB are slightly LREE-rich. These trends require distinct source compositions in HSB relative to LSB/BB. The decrease in Ti/Zr from BB to HSB suggests a slab melt component. Melting models (non-modal, fractional) for boninites require additional partial melting of a residual source more depleted than DMM, and mixing with less depleted melts. The data require a heterogeneous source during subduction initiation, tapping progressively more refractory mantle through time, and showing progressive enrichment in slab components.

Active subsurface cellular function in the Baltic Sea Basin, IODP Exp 347

NASA Astrophysics Data System (ADS)

Reese, B. K.; Zinke, L. A.; Bird, J. T.; Lloyd, K. G.; Marshall, I.; Amend, J.; Jørgensen, B. B.

2016-12-01

The Baltic Sea Basin is a unique depositional setting that has experienced periods of glaciation and deglaciation as a result of global temperature fluctuations over the course of several hundred thousand years. This has resulted in laminated sediments formed during periods with strong permanent salinity stratification. The high sedimentation rates (100-500 cm/1000 y) make this an ideal setting to understand the microbial structure of a deep biosphere community in a high-organic matter environment. The responses of deep sediment microbial communities to variations in conditions during and after deposition are poorly understood. Samples were collected through scientific drilling during the International Ocean Discovery Program (IODP) Expedition 347 on board the Greatship Manisha, September-November 2013. We examined the active microbial community structure using the 16S rRNA gene transcript and active functional genes through metatranscriptome sequencing. Major biogeochemical shifts have been observed in response to the depositional history between the limnic, brackish, and marine phases. The microbial community structure in the BSB is diverse and reflective of the unique changes in the geochemical profile. These data further define the existence life in the deep subsurface and the survival mechanisms required for this extreme environment.

Using Research Data to Stimulate Critical Thinking in Undergraduate Geoscience Courses: Examples and Future Directions

NASA Astrophysics Data System (ADS)

Reed, D. L.; Moore, G. F.; Bangs, N. L.; Tobin, H.

2007-12-01

The results of major research initiatives, such as NSF-MARGINS, IODP and its predecessors DSDP and ODP, Ridge 2000, and NOAA's Ocean Explorer and Vents Programs provide a rich library of resources for inquiry-based learning in undergraduate classes in the geosciences. These materials are scalable for use in general education courses for the non-science major to upper division major and graduate courses, which are both content-rich and research-based. Examples of these materials include images and animations drawn from computer presentations at research workshops and audio/video clips from web sites, as well as data repositories, which can be accessed through GeoMapApp, a data exploration and visualization tool developed as part of the Marine Geoscience Data System by researchers at the LDEO (http://www.geomapapp.org/). Past efforts have focused on recreating sea-going research experiences by integrating and repurposing these data in web-based virtual environments to stimulate active student participation in laboratory settings and at a distance over the WWW. Virtual expeditions have been created based on multibeam mapping of the seafloor near the Golden Gate, bathymetric transects of the major ocean basins, subduction zone seismicity and related tsunamis, water column mapping and submersible dives at hydrothermal vents, and ocean drilling of deep-sea sediments to explore climate change. Students also make use of multichannel seismic data provided through the Marine Seismic Data Center of UTIG to study subduction zone processes at convergent plate boundaries. We will present the initial stages of development of a web-based virtual expedition for use in undergraduate classes, based on a recent 3-D seismic survey associated with the NanTroSEIZE program of NSF-MARGINS and IODP to study the properties of the plate boundary fault system in the upper limit of the seismogenic zone off Japan.

The Nicobar Fan and sediment provenance: preliminary results from IODP Expedition 362, NE Indian Ocean

NASA Astrophysics Data System (ADS)

Pickering, K. T.; Pouderoux, H.; Milliken, K. L.; Carter, A.; Chemale, F., Jr.; Kutterolf, S.; Mukoyoshi, H.; Backman, J.; McNeill, L. C.; Dugan, B.; Expedition 362 Scientists, I.

2017-12-01

IODP Expedition 362 (6 Aug-6 Oct 2016) was designed to drill the input materials of the north Sumatran subduction zone, part of the 5000 km long Sunda subduction system and to understand the origin of the Mw 9.2 earthquake and tsunami that devastated coastal communities around the Indian Ocean in 2004 linked to unexpectedly shallow seismogenic slip and a distinctive forearc prism structure (1,2,3). Two sites, U1480 and U1481 on the Indian oceanic plate 250 km SW of the subduction zone on the eastern flank of the Ninetyeast Ridge, were drilled, cored, and logged to a maximum depth of 1500 m below seafloor. The input materials of the north Sumatran subduction zone are a thick (up to 4-5 km) succession mainly of Bengal-Nicobar Fan siliciclastic sediments overlying a mainly pelagic/hemipelagic succession, with igneous and volcaniclastic material above oceanic basement. At Sites U1480 and U1481, above the igneous basement ( 60-70 Ma), the sedimentary succession comprises deep-marine tuffaceous deposits with igneous intrusions, overlain by pelagic deposits, including chalk, and a thick Nicobar Fan succession of sediment gravity-flow (SGF) deposits, mainly turbidites and muddy debrites. The Nicobar Fan deposits (estimated total volume of 9.2 x 106 km3: 3) represent >90% of the input section at the drill sites and many of the beds are rich in plant material. These beds are intercalated with calcareous clays. Sediment accumulation rates reached 10-40 cm/kyr in the late Miocene to Pliocene, but were much reduced since 1.6 Ma. The onset of Nicobar Fan deposition at the drill sites ( 9.5 Ma; 2) is much younger than was anticipated precruise ( 30-40 Ma), based on previous regional analyses of Bengal-Nicobar Fan history and presumptions of gradual fan progradation. Our preliminary results suggest that the Nicobar Fan was active between 1.6 and 9.5 Ma, and possibly since 30 Ma (3). The observed mineralogical assemblage of the SGF deposits and zircon age dating are consistent with a provenance from a northerly Himalayan and Indo-Burmese source area. 1. Dugan, McNeill, Petronotis, and the Expedition 362 Scientists, 2017. https://doi.org/10.14379/iodp.pr.362.2017. 2. Hüpers, and the Expedition 362 Scientists. Science, 356, 841-844. 3. McNeill, and the Expedition 362 Scientists 2017. Earth and Planetary Science Letters, in press.

Ocean Drilling Program: Public Information: News

Science.gov Websites

site ODP's main web site ODP/TAMU Science Operator Home Ocean Drilling Program News The Ocean Drilling Program was succeeded in 2003 by the Integrated Ocean Drilling Program (IODP). The IODP U.S. Implementing

Methane hydrate formation in turbidite sediments of northern Cascadia, IODP Expedition 311

USGS Publications Warehouse

Torres, M.E.; Trehu, A.M.; Cespedes, N.; Kastner, M.; Wortmann, U.G.; Kim, J.-H.; Long, P.; Malinverno, A.; Pohlman, J.W.; Riedel, M.; Collett, T.

2008-01-01

Expedition 311 of the Integrated Ocean Drilling Program (IODP) to northern Cascadia recovered gas-hydrate bearing sediments along a SW-NE transect from the first ridge of the accretionary margin to the eastward limit of gas-hydrate stability. In this study we contrast the gas gas-hydrate distribution from two sites drilled ~ 8??km apart in different tectonic settings. At Site U1325, drilled on a depositional basin with nearly horizontal sedimentary sequences, the gas-hydrate distribution shows a trend of increasing saturation toward the base of gas-hydrate stability, consistent with several model simulations in the literature. Site U1326 was drilled on an uplifted ridge characterized by faulting, which has likely experienced some mass wasting events. Here the gas hydrate does not show a clear depth-distribution trend, the highest gas-hydrate saturation occurs well within the gas-hydrate stability zone at the shallow depth of ~ 49??mbsf. Sediments at both sites are characterized by abundant coarse-grained (sand) layers up to 23??cm in thickness, and are interspaced within fine-grained (clay and silty clay) detrital sediments. The gas-hydrate distribution is punctuated by localized depth intervals of high gas-hydrate saturation, which preferentially occur in the coarse-grained horizons and occupy up to 60% of the pore space at Site U1325 and > 80% at Site U1326. Detailed analyses of contiguous samples of different lithologies show that when enough methane is present, about 90% of the variance in gas-hydrate saturation can be explained by the sand (> 63????m) content of the sediments. The variability in gas-hydrate occupancy of sandy horizons at Site U1326 reflects an insufficient methane supply to the sediment section between 190 and 245??mbsf. ?? 2008 Elsevier B.V.

Mineralogical influences on porosity-depth trends of shelf deposits (Miocene-Pleistocene) along the northwest shelf of Australia (IODP Expedition 356)

NASA Astrophysics Data System (ADS)

Knierzinger, Wolfgang; Lee, Eun Young; Wagreich, Michael

2017-04-01

Porosity in sediments is influenced by various factors such as mineralogical composition, burial depth, connate fluids, and stratigraphic layering. This work focuses on processes underlying porosity anomalies in carbonate shelf deposits along the northwest shelf of Australia by using different techniques (polarization microscopy, electron microscopy, XRD, XRF). IODP expedition 356 recovered cored seven sites (U1458-U1464), covering a latitudinal range of 29°S-18°S on the northwest shelf. Strong negative deviations from general porosity-depth trends for these carbonate rich sediments are clear for samples with higher contents of dolomite, calcium sulfates, and non-skeletal calcite. No significant influence of aragonite on porosity values has yet been detected. However, it is likely that the occurrence of high amounts of aragonite is a crucial element with regard to porosity values in these carbonate rich deposits, since elongated aragonite needles commonly enhance interparticle porosity. Further insight might be gained through the application of electron microscopy. In general, sediments in the northern part of the study area (Sites U1462, U1463, U1464) tend to show slightly higher porosity values compared to sediments form the south (Sites U1459, U1460). This may reflect the influence of calcium sulfate, because mineralogical analyses show, calcium sulfate is relatively rare at the southern sites, whereas higher amounts of calcium sulfates occur in the north. The lack of detrital particles in calcium sulfate components indicates an evaporitic origin. Deposits at Site U 1461 differ from other analyzed sediments insofar as higher amounts of feldspars and micas are apparent. *This research is conducted within the frame of the 'International Ocean Discovery Program', funded by the Ministry of Oceans and Fisheries, Korea.

Paleomagnetic and rock magnetic study of the IODP Site U1332 sediments - relative paleointensity during Eocene and Oligocene

NASA Astrophysics Data System (ADS)

Yamamoto, Y.; Acton, G.; Channell, J. E.; Palmer, E. C.; Richter, C.; Yamazaki, T.

2011-12-01

Integrated Ocean Drilling Program (IODP) Expeditions 320 and 321 recovered sediment cores from equatorial Pacific. Cores were taken at eight Sites (U1331-U1338) and onboard measurements showed that those from Sites U1331, U1332, U1333 and U1334 covered Eocene and/or Oligocene (Expedition 320/321 Scientists, 2010). Although many efforts have been made to reveal relative geomagnetic paleointensity variations in geologic time, those prior to ca. 3 m.y. have been not yet reported except a few studies (e.g. ca. 23-34 Ma, Tauxe and Hartl, 1997). This study concentrates on paleomagnetic and rock magnetic measurements on the Site U1332 sediment core. The measurements include stepwise alternating field demagnetization of the natural remanent magnetization (NRM), the anhysteretic remanent magnetization (ARM) and the isothermal remanent magnetization (IRM). The magnetostrartigraphy constructed from the NRM data show that the sedimentary section extends from the early Oligocene to middle Eocene (23.030-41.358 Ma). Intensity variation of ARM and IRM is within about a factor of six throughout the core. Magnetic grain size proxy, ARM/IRM, differ between Eocene (about 0.11) and Oligocene (about 0.14). These suggest that relative paleointensity (RPI) estimation is basically possible if we divide the core into Eocene and Oligocene periods. RPI estimates have been done by using ARM and IRM as normalizers for NRM. RPIs by ARM and IRM generally show consistent variations. However, several experimental results imply that RPI by IRM may be more preferable. We will compare the U1332 RPI record with the U1331, U1333 and U1334 RPI records.

Calcareous nannoplankton assemblages across the Pliocene-Pleistocene transition in the southwestern Indian Ocean, IODP Site U1475

NASA Astrophysics Data System (ADS)

Cares, Z.; Farr, C. L.; LeVay, L.; Tangunan, D.; Brentegani, L.

2017-12-01

International Ocean Discovery Program (IODP) Expedition 361 cored six sites along the greater Agulhas Current System to track its intensity through time and to better understand its role in global oceanic circulation and climate. One of the main scientific objectives of this expedition was to determine the dynamics of the Indian-Atlantic Ocean Gateway circulation during Pliocene-Pleistocene climate changes in association with changing wind fields and migrating ocean fronts. The Indian-Atlantic Ocean Gateway contains a pronounced oceanic frontal system, the position of which has the potential to influence global climate on millennial scales. Owing to the physical differences between the frontal zones, this region has complex biogeochemistry, changes in phytoplankton distribution, and variations in primary productivity. Site U1475 was cored on the Agulhas Plateau in the Southwestern Indian Ocean and recovered a complete sequence of calcareous ooze spanning the last 7 Ma. Previous studies at this locality have shown latitudinal migrations of the frontal zones over the past 350 kyr that resulted in prominent millennial shifts in primary production, biological pump efficiency, and microfossil assemblages that coincide with Antarctic climate variability. Here we present initial results comprised of calcareous nannoplankton assemblages in order to test if similar latitudinal frontal migrations occurred during the Pliocene-Pleistocene transition (PPT; 2.7 Ma). The calcareous nannoplankton assemblage shows an abundance increase of taxa associated with cooler water and higher primary production across the PPT interval. In addition to a change in species abudance, the Shannon diversity index drops notably across the transition, which is typical of nannoplankton communities in more productive regions. These data suggest that a long-term change in sea surface temperature and nutrient availability took place across the PPT, potentially linked to the northward migration of frontal zones.

IODP Expedition 352 (Bonin Forearc): First Results

NASA Astrophysics Data System (ADS)

Pearce, J. A.; Reagan, M. K.; Stern, R. J.; Petronotis, K. E.

2014-12-01

IODP Expedition #352 (Testing Subduction Initiation and Ophiolite Models by Drilling the Outer Izu-Bonin-Mariana Forearc: July 30-Sept. 29, 2014) is just underway at the time of writing. It is testing the Stern-Bloomer hypothesis that subduction initiation (SI) was followed by a strongly extensional period of slab sinking and trench roll-back and then by a transitional period leading to the establishment of significant slab-parallel plate motion and hence normal subduction. The Expedition aims to carry out offset drilling at two sites near 28°30'N in the Bonin forearc. Ideally, these together will give the vertical volcanic stratigraphy needed to trace the geodynamic and petrogenetic processes associated with SI, and provide the complete reference section required for comparison with volcanic sequences of possible SI origin found on land in ophiolite complexes and elsewhere. We predict, but need to confirm, a c. 1.0-1.5km sequence with basal, MORB-like forearc basalts (known as FAB) marking the initial period of extension, boninites characterizing the transitional period, and tholeiitic and calc-alkaline lavas marking the establishment of normal arc volcanism. Study of such a sequence will enable us to understand the chemical gradients within and across these volcanic units, to reconstruct mantle flow and melting processes during the course of SI, and to test the hypothesis that fore-arc lithosphere created during SI is the birthplace of most supra-subduction zone ophiolites. Here, we present the first Expedition results, including (a) the volcanic stratigraphic record and subdivision into lava units, (b) the classifications and interpretations made possible by shipboard (portable XRF and ICP) analyses and down-hole measurements, and (c) the biostratigraphic, magnetic, mineralogical, sedimentary and structural constraints on the geological history of the SI section and the interactions between magmatic, hydrothermal and tectonic activity during its evolution.

Pleistocene Through Oligocene Record of Himalayan Orogeny and Climate. The Iodp Expedition 354 Drilling Transect across the Middle Bengal Fan at 8°N

NASA Astrophysics Data System (ADS)

Spiess, V.; France-Lanord, C.; Schwenk, T.; Klaus, A.

2015-12-01

IODP Expedition 354 in the Bay of Bengal February-March 2015 drilled a seven site, 320 km-long transect across the Bengal Fan at 8°N. Three deep penetration and additional four shallow holes provided a spatial overview of the primarily turbiditic depositional system, comprising the Bengal deep sea fan. Sediments originate from Himalayan rivers, documenting terrestrial changes of the monsoon evolution and Himalayan erosion and weathering, and are transported through a delta and shelf canyon, supplying turbidity currents loaded with a full spectrum of grain sizes. Mostly following transport channels, sediments deposit on and between levees, while depocenters are laterally shifting over hundreds of kilometers on millennial time scales. Expedition 354 documented these deposits in space and time by identifying, coring and dating numerous stratigraphic marker horizons across the transect, allowing a detailed reconstruction of channel-levee migration, abandonment, reoccupation and overall uniform growth in the late Pleistocene. High resolution records of these growth patterns were acquired in several levee, interlevee and hemipelagic successions. Miocene through Pliocene fan development was studied at three deeper sites, which document and recovered sand rich facies throughout most of the cores acquired by the half-APC coring technology, intercalated by longer periods of hemipelagic deposition and absence of turbiditic input as the results of major depocenter shifts. Recovered sediments have Himalayan mineralogical and geochemical signatures suitable to reconstruct time series of erosion, weathering and changes in source regions as well as impacts on the global carbon cycle. Miocene shifts in terrestrial vegetation, in sediment budget and in style of sediment transport have been tracked. Expedition 354 has extended the record of early fan deposition by 10 Ma into the Late Oligocene.

Fossil ostracodes of continental shelf cores at IODP Site U1354 (Expedition 317)

NASA Astrophysics Data System (ADS)

Kusunoki, S.; Ohi, T.; Kawagata, S.; Ishida, K.; Shipboard Scientific Party, E.

2010-12-01

Integrated Ocean Drilling Program (IODP) Expedition 317 was devoted to understanding the relative importance of global sea level (eustasy) versus local tectonic and sedimentary processes in controlling continental margin sedimentary cycles. The expedition recovered sediments from the Eocene to recent period, with a particular focus on the sequence stratigraphy of the late Miocene to recent, when global sea level change was dominated by glacioeustasy. Drilling in the Canterbury Basin, on the eastern margin of the South Island of New Zealand took advantage of high rates of Neogene sediment supply, which preserved a high-frequency (0.1-0.5 m.y.) record of depositional cyclicity. Ostracodes are crustaceans that widely inhabit marine, brackish, and non-marine environments. Shallow marine species have more restricted habitat and respond sensitively to environmental changes. Therefore they are a useful tool for high-resolution analyses of paleoenvironmental changes. We study samples older than ~1.0 Ma from Site U1354, which is in an intermediate position within the three shelf sites transect of Expedition 317. Quaternary to early Pliocene (~4.5 Ma) sediments were cored in this site with best core recovery (81%) among the shelf sites. The period from the Pliocene to Pleistocene is known for distinct paleoclimatic changes, from the intensive warming at around 3.5 Ma, to the cooling stage starting from 2.75 Ma. We expect that high-resolution analyses of fossil ostracode assemblages reveal detailed sea level and paleoceanographic changes on the continental shelf of the Canterbury Basin caused by global climate changes. Samples were examined at 1.5 m depth intervals. Samples of ~20 cc were freeze-dried and washed through a 63 µm opening sieve. The residues were dried and then divided into aliquot parts containing around 200 specimens using a sample splitter. All individual ostracodes were picked from residues coarser than 125 µm. Valves and carapaces were counted as one specimen. Well preserved ostracodes were found abundantly between the interval of 75 to 100 m (1 to 1.5 Ma) below the sea floor, although many of them are juvenile sized 125-250 µm. The numbers of ostracode specimens in each sample are from 20 to around 1100 per 20 cc and increase upward.

Physical Properties and Seismic Structure of Izu-Bonin-Mariana Fore Arc crust: Results From IODP Expedition 352 and Comparison with Oceanic Crust

NASA Astrophysics Data System (ADS)

Christeson, G. L.; Morgan, S.; Kodaira, S.; Yamashita, M.

2015-12-01

Most of the well-preserved ophiolite complexes are believed to form in supra-subduction zone settings. One of the goals of IODP Expedition 352 was to test the supra-subduction zone ophiolite model by drilling forearc crust at the northern Izu-Bonin-Mariana (IBM) system. IBM forearc drilling successfully cored 1.22 km of volcanic lavas and underlying dikes at four sites. A surprising observation is that basement compressional velocities measured from downhole logging average ~3.0 km/s, compared to values of 5 km/s at similar basement depths at oceanic crust sites 504B and 1256D. Typically there is an inverse relationship in extrusive lavas between velocity and porosity, but downhole logging shows similar porosities for the IBM and oceanic crust sites, despite the large difference in measured compressional velocities. These observations can be explained by a difference in crack morphologies between IBM forearc and oceanic crust, with a smaller fractional area of asperity contact across cracks at EXP 352 sites than at sites 504B and 1256D. Seismic profiles at the IBM forearc image many faults, which may be related to the crack population.

Orbitally-resolved SST Changes during the EOT: Results from IODP 342 Expedition

NASA Astrophysics Data System (ADS)

Liu, Z.; He, Y.; Wilson, P. A.; Pagani, M.

2014-12-01

Sea surface temperature (SST) changes during the Eocene-Oligocene climate transition were characterized by substantial cooling at high latitudes and less cooling in low latitudes, with little information from mid-latitudes so far. Taking advantage of the newly retrieved drift sediments from the IODP 342 Expedition, we aim to reconstruct SST changes at the mid-latitude Newfoundland region, at an unprecedented orbital resolution from Site U1411. During the period investigated, 32-36 Ma, the alkenone UK'37 values range from 0.65 to 0.95, with values all greater than 0.80 before the transition and lower values (<0.80) occurring approximately at the eccentricity minimum nodes after the transition. No immediate cooling associated with Oi-1 glaciation was observed. During the Oligocene, SSTs during warm epochs (corresponding to eccentricity maxima) were not significantly cooler than before. Overall, SST fluctuations appear to be modulated by orbital changes throughout the record, although more apparent due to larger amplitude of SST variability after the transition. We thus hypothesize that the mid-latitude Newfoundland region was largely bathed by low-latitude warm waters during the transition and that polar waters (fronts) reached to the region occasionally at periods of eccentricity minimum nodes during the Oligocene.

Paleomagnetic field variability and chronostratigraphy of Brunhes-Chron deep-sea sediments from the Bering Sea: IODP Expedition 323

NASA Astrophysics Data System (ADS)

Lund, Steve; Stoner, Joseph; Okada, Makoto; Mortazavi, Emily

2016-03-01

IODP Expedition 323 recovered six complete and replicate records of Brunhes-Chron paleomagnetic field variability (0-780,000 years BP) in 2820 m core depth below sea floor (CSF) of deep-sea sediments. On shipboard, we made more than 220,000 paleomagnetic measurements on the recovered sediments. Since then, we have u-channel sampled more than 300 m of Brunhes Chron sediments to corroborate our shipboard measurements and improve our paleomagnetic and rock magnetic understanding of these sediments. Several intervals of distinctive paleomagnetic secular variation (PSV) have been identified that appear to be correlatable among sites 1343, 1344, and 1345. One magnetic field excursion is recorded in sediments of sites 1339, 1343, 1344, and 1345. We identify this to be excursion 7α/Iceland Basin Event (192,000 years BP), which is also seen in the high-latitude North Atlantic Ocean (Channell et al., 1997). We have verified in u-channels the placement of the Brunhes/Matuyama boundary (780,000 years BP) at sites 1341 and 1343. Finally, we have developed a medium-quality relative paleointensity record for these sediments that is correlatable among the sites, even though it is still biased by large-amplitude environmental variability. On the basis of these observations we have built a magnetic chronostratigraphy of Expedition 323 sediments suitable for regional correlation and dating over the last 1 million years, and compared this with oxygen-isotope chronostratigraphy from sites U1339 and U1345.

One Dimensional Backstripping Results from IODP Expedition 318, Site U1356: Tectonic Implications for the Wilkes Land Margin of Antarctica

NASA Astrophysics Data System (ADS)

Hayden, T. G.; Kominz, M. A.; González, J. J.; Escutia, C.; Brinkhuis, H.; Scientific Party of IODP Expedition 318

2011-12-01

The Wilkes Land margin of Antarctica is the conjugate margin of the Great Australian Bight, which underwent extension, thinning and rifting from ~160 Ma until breakup at ~83 Ma. Both Wilkes Land and the Great Australian Bight are considered passive margins, and were thought to be tectonically inactive since breakup at 83 Ma. We have backstripped the U1356 Core recovered from the continental rise off Wilkes Land, Antarctica by IODP Expedition 318. Backstripping input included lithological and sedimentary analysis, paleo-environmental indicators, combined paleomagnetic and biostratigraphic chronologies, and physical properties measurements. Tectonic subsidence shows a major event between 50 and 33.6 Ma, a time represented by a hiatus in the U1356 core. The magnitude of subsidence requires it to be tectonic in origin, and the timing matches with a reorganization of plate motions that represents the transition from slow spreading to fast spreading between Antarctica and Australia, which occurred at approximately 43 Ma. Coupled with a regional seismic framework, and using other Expedition 318 site analyses, the Wilkes Land margin is shown to be far more complex then the simple passive margin currently assumed. We explore several possible mechanisms for the subsidence and erosion observed; including thermal uplift due to continental insulation of the asthenosphere and it's interaction with a recently rifted margin, asthenospheric convection, transtensional or transpressional basin development and loading, and edge-driven asthenospheric convection.

Raman Spectroscopy: an essential tool for future IODP expeditions

NASA Astrophysics Data System (ADS)

Andò, Sergio; Garzanti, Eduardo; Kulhanek, Denise K.

2016-04-01

The scientific drilling of oceanic sedimentary sequences plays a fundamental part in provenance studies, paleoclimate recostructions, and source-to-sink investigations (e.g., France-Lanord et al., 2015; Pandey et al., 2015). When studying oceanic deposits, Raman spectroscopy can and does represent an essential flexible tool for the multidisciplinary approach necessary to integrate the insight provided by different disciplines. This new user-friendly technique opens up an innovative avenue to study in real time the composition of detrital mineral grains of any origin, complementing traditional methods of provenance analysis (e.g., sedimentary petrography, heavy minerals; Andò and Garzanti, 2014). Raman spectra can readily reveal the chemistry of foraminiferal tests, nannofossils and other biogenic debris for the study of ecosystem evolution and paleoclimate, or the Ca/Mg ratio in biogenic or terrigenous carbonates for geological or marine biological applications and oil exploration (Borromeo et al., 2015). For the study of pelagic or turbiditic muds, which represent the bulk of the deep-marine sedimentary record, Raman spectroscopy allows us to identify silt-sized grains down to the size of a few microns with the same precision level required in quantitative provenance analysis of sand-sized sediments (Andò et al., 2011). Silt and siltstone also represent a very conspicuous part of the stratigraphic record onshore and usually preserve original mineralogical assemblages better than more permeable interbedded sand and sandstone (Blatt, 1985). Raman spectra can be obtained on sample volumes of only a few cubic microns by a confocal micro-Raman coupled with a standard polarizing light microscope using a 50× objective. The size of this apparatus can be easily placed onboard an IODP vessel to provide crucial information and quickly solve identification problems for the benefit of a wide range of scientists during future expeditions. Cited references Andò, S., Vignola, P., Garzanti, E., 2011. Raman counting: a new method to determine provenance of silt. Rend. Fis. Acc. Lincei, 22: 327-347. Andò, S., Garzanti, E., 2014. Raman spectroscopy in heavy-mineral studies. Geological Society, London, Special Publications, 386 (1), 395-412. Blatt, H., (1985). Provenance studies and mudrocks. Journal of Sedimentary Research, 55 (1), 69-75. Borromeo, L., Zimmermann, U., Andò, S., Coletti, G., Bersani, D., Basso, D., Gentile, P., Garzanti, E., 2015. Raman Spectroscopy as a tool for magnesium estimation in Mg-calcite. Periodico di Mineralogia , ECMS, 35-36. France-Lanord, C., Spiess, V., Klaus, A., and the Expedition 354 Scientists, 2015. IODP, Exp. 354, Preliminary Report: Bengal Fan, Neogene and late Paleogene record of Himalayan orogeny and climate: a transect across the Middle Bengal Fan. Pandey, D.K., Clift, P.D., Kulhanek, D.K. and the Expedition 355 Scientists, 2015. IODP, Exp. 355, Preliminary Report: Arabian Sea Monsoon, Deep sea drilling in the Arabian Sea: constraining tectonic-monsoon interactions in South Asia.

Physical properties of the Nankai inner accretionary prism sediments at Site C0002, IODP Expedition 348.

NASA Astrophysics Data System (ADS)

Kitamura, M.; Kitajima, H.; Henry, P.; Valdez, R. D., II; Josh, M.; Tobin, H. J.; Saffer, D. M.; Hirose, T.; Toczko, S.; Maeda, L.

2014-12-01

Integrated Ocean Drilling Program (IODP) Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) Expedition 348 focused on deepening the existing riser hole at Site C0002 to ~3000 meters below seafloor (mbsf) to access the deep interior of the Miocene inner accretionary prism. This unique tectonic environment, which has never before been sampled in situ by ocean drilling, was characterized through riser drilling, logging while drilling (LWD), mud gas monitoring and sampling, and cuttings and core analysis. Shipboard physical properties measurements including moisture and density (MAD), electrical conductivity, P-wave, natural gamma ray, and magnetic susceptibility measurements were performed mainly on cuttings samples from 870.5 to 3058.5 mbsf, but also on core samples from 2163 and 2204 mbsf. MAD measurements were conducted on seawater-washed cuttings ("bulk cuttings") in two size fractions of >4 mm and 1-4 mm from 870.5 to 3058.5 mbsf, and hand-picked intact cuttings from the >4 mm size fractions within 1222.5-3058.5 mbsf interval. The bulk cuttings show grain density of ~2.7 g/cm3, bulk density of 1.9 g/cm3 to 2.2 g/cm3, and porosity of 50% to 32%. Compared to the values on bulk cuttings, the intact cuttings show almost the same grain density, but higher bulk density and lower porosity, respectively. Combined with the MAD measurements on hand-picked intact cuttings and discrete core samples from previous expeditions, porosity generally decreases from ~60% to ~20% from the seafloor to 3000 mbsf at Site C0002. Electrical conductivity and P-wave velocity on discrete samples, which were prepared from both cuttings and core samples in the depth interval of 1745.5-3058.5 mbsf, range 0.15-0.9 S/m and 1.7-4.5 km/s, respectively. The electrical resistivity on discrete samples is higher than the LWD resistivity data but the overall depth trends are similar. The electrical conductivity and P-wave velocity on discrete samples corrected for in-situ pressure and temperature will be presented. The shipboard physical properties measurements on cuttings are very limited but can be useful with careful treatment and observation.

Deciphering the Transitional Tectonics of the Southern Alaska Margin Through Gulf Sedimentology and Geophysics: IODP Expedition 341

NASA Astrophysics Data System (ADS)

Reece, R.; Gulick, S. P. S.; Jaeger, J. M.

2014-12-01

Southern Alaska is a complex amalgam of tectonic environments, centered on the subduction/collision of the Yakutat Block with North America. Along the Aleutians in the west, the Pacific Plate subducts normally beneath North America, with a gradually shallowing subduction angle towards the Yakutat Terrane to the east. The western region of the Yakutat Block undergoes nearly flat-slab subduction beneath North America, whereas it transitions to collision in the northeast, which is the primary driver for the growth of the Chugach-St. Elias orogen. Farther to the east, the collisional system transitions to a transform boundary with the Fairweather-Queen Charlotte fault system. The collisional system contributes to farfield tectonic effects in many regions, including northern Alaska and the Pacific Plate, but also combines with glaciation to drive sedimentation in the Gulf of Alaska. Glaciation has periodically increased in the St. Elias Range since the Miocene, but began dominating erosion and spurred enhanced exhumation since the intensification of Northern Hemisphere glaciation, at ~2.5 Ma. Results from IODP Expedition 341 show the first appearance of ice-rafted debris and a doubling of Gulf sedimentation at site U1417 at this age, and a major increase in sedimentation at ~1 Ma at sites U1417 and U1418. Glacigenic sediment flux into the Gulf of Alaska represents the majority of accumulation in the deepwater Surveyor Fan, and was the impetus for formation of the Surveyor Channel system. Climate events correlate to three major differentiable sequences across the Surveyor Fan that have been previously mapped using seismic reflection profiles. The change in morphology observed throughout the sequences allows us to characterize the influence that a glaciated orogen can have in shaping margin processes and the sediment pathways from source to sink. IODP Expedition 341 results allow us to now apply this method at higher resolution time scales (i.e., 100 kyr). We will explore changes in fan geomorphology observed in seismic reflection data to decipher changes in southern Alaska tectonics and climate, and to show the effect of those changes on deepwater sedimentary systems.

First results from IODP Expedition 325 to the Great Barrier Reef: unlocking climate and sea level secrets since the Last Glacial Maximum

NASA Astrophysics Data System (ADS)

Webster, J. M.; Yokoyama, Y.; Cotterill, C.; Expedition 325 Scientists

2010-12-01

Integrated Ocean Drilling Program (IODP) Exp. 325 (GBREC: Great Barrier Reef Environmental Change) that investigated fossil reefs on the shelf edge of the Great Barrier Reef (GBR), was the fourth IODP expedition to use a mission-specific platform, and was conducted by the European Consortium for Ocean Research Drilling (ECORD) Science Operator (ESO). The scientific objectives are to establish the course of sea level change, define sea-surface temperature variations, and to analyze the impact of these environmental changes on reef growth and geometry over the period of 20-10 ka. Exp.325 complements and extends the findings of the 2005 Exp. 310 (Tahiti Sea Level) that recovered Postglacial coral reef cores from the flanks of Tahiti from 41.6-117.5 meters below sea level and spanned ~16 to ~8 ka. Preliminary data confirms that Exp. 325 recovered truly unique and valuable fossil coral reef material from key periods in Earth's sea level and climate history from 30 to 9 ka. On Exp. 325 a succession of fossil reef structures preserved on the shelf edge seaward of the modern barrier reef were cored at three geographic locations (Hydrographers Passage, Noggin Pass and Ribbon Reef) from a dynamically positioned vessel in February-April 2010. A total of 34 boreholes were cored from 17 sites in four transects at depths ranging from 42.2 to 167.2 meters below sea level. Borehole logging of four boreholes provided continuous geophysical information about the drilled strata. The cores were split and described during the Onshore Science Party at the IODP Bremen Core Repository (Germany) in July 2010, where minimum and some standard measurements were made. Initial lithologic and biologic observations identified high-quality fossil coralgal frameworks, consistent with shallow, high energy reef settings - crucial for precise reconstructions of sea level and paleoclimate change. Preliminary C14-AMS and U-Th age interpretations from 60 core catcher samples confirmed that the cores span ages from >30 to 9 ka. This chronology, combined with their recovered depths, clearly demonstrates that Exp. 325 recovered coral reef material from key periods of interest for sea level change and environmental reconstruction, including the Last Glacial Maximum, Heinrich Events 1 and 2, 19ka-MWP, Bølling-Allerød, MWP1A, the Younger Dryas and MWPB. The new Exp. 325 cores are especially important because few fossil coral records span these intervals, and even fewer are from stable, passive margin settings far from the confounding influences of ice sheets or tectonic activity. This paper summarizes Exp. 325’s first results and their broader implications for understanding global sea-level and paleoclimate changes, and provides a first interpretation of how these reefs responded to environmental stress.

Paleothermal structure of the Nankai inner accretionary wedge estimated from vitrinite reflectance of cuttings

NASA Astrophysics Data System (ADS)

Fukuchi, Rina; Yamaguchi, Asuka; Yamamoto, Yuzuru; Ashi, Juichiro

2017-08-01

The paleothermal structure and tectonic evolution of an accretionary prism is basic information for understanding subduction zone seismogenesis. To evaluate the entire paleotemperature profile of the Integrated Ocean Drilling Program (IODP) Site C0002 located in the off-Kumano region of the Nankai Trough and penetrate the inner accretionary wedge down to 3058.5 m below the seafloor (mbsf), we performed a vitrinite reflectance analysis for cuttings and core samples during IODP expeditions 338 and 348: Nankai Trough seismogenic zone experiment. Although vitrinite reflectance values (Ro) tend to increase with depth, two reversals of these values suggested the existence of thrust fault zones with sufficient displacements to offset the paleothermal structure. The estimated maximum paleotemperatures are 42-70°C at 1200-1300 mbsf, 44-100°C at 1600-2400 mbsf, and 56-115°C at 2600-3000 mbsf, respectively. These temperatures roughly coincide with estimated modern temperatures; however, at a smaller scale, the reconstructed partial paleogeothermal gradient (˜60-150°C/km) recorded at the hanging- and footwall of the presumed thrust fault zone is higher than the modern geothermal gradient (˜30-40°C/km). This high paleogeothermal gradient was possibly obtained prior to subduction, reflecting the large heat flow of the young Philippine Sea Plate.

XRF Core Scanning of Igneous Rocks: a Case Study of IODP Expeditions 367/368 Lava Flows, South China Sea

NASA Astrophysics Data System (ADS)

Höfig, T. W.; LeVay, B.; Stock, J. M.; Sun, Z.; Klaus, A.; Jian, Z.; Larsen, H. C.; Alvarez Zarikian, C. A.

2017-12-01

For three decades, X-ray fluorescence core scanning (XRF-CS) has been widely applied to split sediment cores to obtain continuous data sets of element intensities, serving as chemical proxies for paleoceanography and paleoclimate studies. In contrast, there is no record published on igneous rock cores. This study utilizes a remarkably consistent recovery of lava flows from the South China Sea (SCS), intersected during International Ocean Discovery Program (IODP) Expeditions 367/368, to gain preliminary insights into the chemical inventory of a volcanic suite. At IODP Site U1500, a drilled interval of 150 m, starting at 1379.1 meters below seafloor, yielded 115 m of intercalated fine-grained massive, sheet, and pillow lava flows of basaltic modal composition, consisting of aphyric to highly plagioclase-phyric rocks. The pillow lavas feature numerous well-preserved chilled and glassy margins. The whole succession of lavas is overall slightly to moderately altered and notably fresh in parts. The present XRF data, obtained from a third-generation energy dispersive Avaatech® core scanner at a step size of 2 cm, suggest the existence of two chemically distinct lava suites. The bottom six lava flows (in total 40 m thick) show low intensities of both Cr and Ti (e.g., Ti: 7000-8500 counts), while the upper 11 flows reflect higher concentrations of Cr and Ti (e.g., Ti: 8200-9500 counts). A massive flow, which marks the chemical transition, represents the top of the low-Cr and -Ti lava suite. The compositional change from low-Cr-Ti to high-Cr-Ti lavas reflects a clear temporal magmatic evolution of this submarine SCS volcanism, which is characterized by generally constant Fe/Mn ratios. Thus, this trend may be explained by a change to less fractionated and/or less contaminated lavas over time. On a smaller scale, the XRF-CS also enabled mapping of the compositional variations of crosscutting veins with depth as well as the transition from glassy margins to the micro- to cryptocrystalline interiors of lava flows. The present preliminary study demonstrates the great potential of XRF-CS of volcanic rocks for not only informational purposes for any subsequent sampling of certain depth intervals but also for offering a non-destructive approach to investigating the downhole chemical variation at high resolution.

X-ray fluorescence results from IODP Expedition 355 sediments in Laxmi Basin, eastern Arabian Sea: Insights into late Miocene and Pleistocene carbonate production and burial and possible variations in monsoon intensit

NASA Astrophysics Data System (ADS)

Bowen, M. G.; Kulhanek, D. K.; Lyle, M. W.; Hahn, A.

2017-12-01

Variations in CaCO3 accumulation on the seafloor depend on a number of factors, including productivity of carbonate-producing organisms in the overlying water column, input of siliciclastic material from nearby continents, and changes in ocean chemistry. These factors are affected by variations in tectonics and climate. Here we use X-ray fluorescence (XRF) core scanning data to develop high-resolution chemical profiles calibrated with discrete samples to examine changes in carbonate production and burial in the eastern Arabian Sea. International Ocean Discovery Program (IODP) Expedition 355 cored two sites in the Indus Fan in Laxmi Basin. We scanned the Pleistocene composite sections from both sites at 2 cm resolution ( 150-300 year sampling resolution) using the Avaatech XRF core scanner at the IODP Gulf Coast Repository. In addition, we scanned a hemipelagic interval dated to the late Miocene ( 8 to 6 Ma) that spans the late Miocene climate transition to drier conditions globally, as documented by an expansion in C4 plants. The 2 cm scanning resolution represents 500 years between samples for the upper Miocene section. We used carbonate measurements on discrete samples to calibrate the XRF data, supplemented by analysis using a quantitative benchtop XRF at the University of Bremen. We find large variability in carbonate content in the Pleistocene and upper Miocene, varying from 15-80 wt%, with higher carbonate content correlating with lighter colored sediment. The aluminosilicate composition varies in part because of carbonate dilution but also because of changes in the source of clays and turbidites through the section. We also explore the use of chemical ratios to better understand the variations through the section. Changes in Ca/Fe (biogenic/terrestrial component) and Rb/Zr (fine/coarse grained) match well with visual observation of sediment composition in the cores. We can combine these with the oxygen isotope-derived age model for the Pleistocene section to examine orbital-scale variations in carbonate production and terrigenous input at the sites. We also explore proxies for precipitation (Ti/Ca) and weathering (Fe/K and Al/K) to elucidate changes in monsoon strength during the Pleistocene, although these results are preliminary.

80 Million Years of Prolonged and Localized Fluid flow on Shatsky Rise

NASA Astrophysics Data System (ADS)

Vermillion, K. B.; Koppers, A.; Heaton, D. E.; Harris, R. N.

2017-12-01

Shatsky Rise is a large igneous province (LIP) in the northwest Pacific Ocean, which formed at an unstable ridge-ridge-ridge (RRR) triple junction at the Jurassic-Cretaceous boundary. High resolution 40Ar/39Ar incremental heating analyses of samples from TAMU and Ori Massif, the two largest volcanic features on Shatsky Rise, yield mixing ages between fresh plagioclase and sericite alteration phases. Mixing ages range from several million years younger to 75 Myr younger than the eruption ages of 147 (TAMU Massif) and 140 Ma (Ori Massif). Sericitic alteration in plagioclase from IODP (Integrated Ocean Drilling Program) Expedition 324 Holes U1347A, U1349A, U1350A and U1346A on TAMU, Ori and Shirshov Massifs suggests pervasive fluid flow throughout Shatsky Rise in the first million years after eruption. Sericitic alteration in plagioclase from ODP (Ocean Drilling Program) Hole 1231B on the flanks of the TAMU Massif also suggests fluid flow. However, localized and very late stage fluid flow is found in the deepest highly altered pillow basalt sequence (Unit IV) of IODP Hole U1350A, where sericitic plagioclase samples is dated to be 65.8, 70.2 and 82.1 Ma. Since the sericite 40Ar/39Ar ages obtained are a mixture between fresh plagioclase and sericite alteration in the plagioclase, we estimate the true age of alteration, using the Verati and Jourdan (Geological Society, London, 2015) mixing model, showing that in IODP Hole U1350A (140 Ma eruption age) the sericite formed around 127 Ma or much later between 85 and 60 Ma. Thermal modeling suggests that throughout Shatsky Rise sustained fluid flow may occur and could be responsible for sericite alteration up to approximately 22 Myr after eruption. During this initial Shatsky Rise cool down phase, the natural geothermal gradient remains high enough to form sericite at temperatures of 100-215 °C. However, the same model shows that the conductive geothermal gradient alone does not sustain enough heat to form sericite 80 Myr after the age of eruption at Ori Massif in Unit IV of IODP Hole U1350A. The overall mechanism driving the additional heat required to form sericite so much later and locally at Ori Massif is still under investigation, but our models suggest that discharging fluids from the crustal aquifer can supply the heat needed for alteration.

Paleomagnetism Onboard the IODP Research Vessel JOIDES Resolution: Recent Advances, Best Practices, and Pitfalls

NASA Astrophysics Data System (ADS)

Acton, G. D.; Morris, A.; Musgrave, R. J.; Zhao, X., , prof; Clement, B. M.; Evans, H. F.; Hastedt, M.; Houpt, D.; Mills, B.; Novak, B.; Petronotis, K. E.

2017-12-01

One of the largest openly available paleomagnetism databases is derived from paleomagnetic data acquired continuously along drill cores collected by the International Ocean Discovery Program (IODP) and its predecessors. The bulk of data are magnetic remanences measured using superconducting rock magnetometers (SRMs) with automated track systems and in-line alternating field (AF) demagnetization units produced by 2G Enterprises. Our goal in this study is to (1) report on the new SRM that was installed onboard the JOIDES Resolution in December 2016 prior to the start of IODP Expedition 366, (2) consider best practices that may aid shipboard scientists in collecting high quality data, and (3) discuss common pitfalls associated with using an SRM in the shipboard environment to measure a diverse range of lithologies collected in metal core barrels that pass through a relatively strongly magnetized drill string. From a series of tests conducted on the new SRM during a June 11-13, 2017 port call, our main conclusion was that the new magnetometer is functioning as designed. While overall its capabilities are comparable to the previous magnetometer, the new SRM does have several significant advances, including better flux counting, which allows more strongly magnetized rocks to be measured accurately. It also performs AF demagnetizations at high fields (up to 80 mT) without imparting spurious anhysteretic magnetizations, which was a common problem in the old SRM. A worrisome observation, and one that has been made in many shore-based labs, is that devices that emit radio-frequency electromagnetic waves, like actively transmitting cell phones, interfere significantly with SRM measurements. This pitfall will likely have to be addressed on all forthcoming cruises unless better electromagnetic shielding for the SQUID sensors can be found.

Carbonate system at Iheya North in Okinawa Trough~IODP drilling and post drilling environment~

NASA Astrophysics Data System (ADS)

Noguchi, T.; Hatta, M.; Sunamura, M.; Fukuba, T.; Suzue, T.; Kimoto, H.; Okamura, K.

2012-12-01

The Iheya North hydrothermal field in middle Okinawa Trough is covered with thick hemipelagic and volcanic sediment. Geochemical characteristics of Okinawa Trough is to provide abundant of CO2, CH4, NH4, H2, and H2S which originated from magmatic gases, sedimentary organic matters. On this hydrothermal field, a scientific drilling by Integrated Ocean Drilling Program (IODP) Expedition 331 was conducted to investigate metabolically diverse subseafloor microbial ecosystem and their physical and chemical settings. To clarify the spatial distribution of physical condition beneath seafloor around the hydrothermal filed, we focus on the carbonate species analysis to reconstruct in-situ pH, which regulate the diversities of microbial community and mineral composition. We developed the small sample volume dissolved total inorganic carbon (DIC) analyzer and conducted the onboard analysis for the interstitial water during IODP Exp.331. Total alkalinity, boron, phosphate, and ammonium also analyzed for thermodynamic calculation. In this presentation, we represent the spatial distribution of pH beneath the Iheya North hydrothermal field. In addition, we developed a 128 bottles multiple water sampler (ANEMONE) for post drilling environmental monitoring. ANEMONE sampler was deployed on the manned submersible Shinkai 6500 with other chemical sensors (CTD, turbidity, pH, ORP, and H2S), and collected the hydrothermal plume samples every 5 minutes during YK12-05 cruise by R/V Yokosuka (Japan Agency for Marine-Earth Science and Technology, JAMSTEC). DIC concentration of plume samples collected by ANEMONE sampler were analyzed just after submersible retrieve, and nutrients, manganese, density, and total cell counts determination were conducted onshore analysis. Based on these results, we describe the spatial distribution of DIC and carbonate system on Iheya North hydrothermal field (interstitial water, hydrothermal fluid, and hydrothermal plume).

High-Resolution Magnetic Properties and Cyclicity of Contourites from IODP Site U1389 (West Iberian Margin)

NASA Astrophysics Data System (ADS)

Richter, C.; Adesiyun, O.; Acton, G.; Sidorovskaia, N.; Sierro, F. J.; Xuan, C.; Verosub, K. L.

2015-12-01

We present high-resolution paleomagnetic and rock magnetic results from the lower part of the APC-cored section (36 - 107 meters composite depth) of Integrated Ocean Drilling Program (IODP) Site U1389 (36º 25.515'N; 7º 16.683'W, 644 m water depth). This site was cored as part of the IODP Mediterranean Outflow Expedition to address paleoceanographic questions about the evolution of the North Atlantic Mediterranean and climate system over the past 6 million years. The recovered section at Site U1389 consists of a thick, rapidly accumulated (~40 cm/kyr), and very uniform series of contouritic sediment. Ages were obtained by tuning the planktonic foraminifer oxygen isotope data to the NGRIP ice core record. We collected rock magnetic and paleomagnetic measurements at 1-cm resolution on 71-m of U-channel samples (representing ~145 k.yr.), with the goal of extracting a high-resolution record of paleoenvironmental variability, relative geomagnetic paleointensity, and paleosecular variation. Stepwise demagnetization of the natural remanence (NRM) demonstrates the successful removal of a secondary, predominantly drill-string induced, magnetization and identification of a stable and strong primary magnetization carried by the sediment samples (average MAD calculated by principal component analysis: ~1º). Excellent behavior of the samples during alternating field demagnetization and isothermal remanent magnetization (IRM) acquisition suggest magnetite as the main carrier of magnetic remanence. Relative paleointensity estimates were determined by normalizing the NRM by the ARM, IRM, and magnetic susceptibility. Time-frequency analyses of high-resolution concentration and grain-size dependent paleomagnetic proxy data for the entire 107-m (200 k.yr.) long APC section of Site U1389 will be presented with the goal of identifying the driver of cyclic changes in the sedimentary section.

Ocean Drilling Program: Cruise Information

Science.gov Websites

Morgan. Cruise Information The Ocean Drilling Program ended on 30 September 2003 and has been succeeded by the Integrated Ocean Drilling Program (IODP). The U.S. Implementing Organization (IODP-USIO ) (Consortium for Ocean Leadership, Lamont-Doherty Earth Observatory, and Texas A&M University) continues to

Evidence for Methyl-Compound-Activated Life in Coal Bed System 2 km Below Sea Floor

NASA Astrophysics Data System (ADS)

Trembath-reichert, E.; Morono, Y.; Dawson, K.; Wanger, G.; Bowles, M.; Heuer, V.; Hinrichs, K. U.; Inagaki, F.; Orphan, V. J.

2014-12-01

IODP Expedition 337 set the record for deepest marine scientific drilling down to 2.4 kmbsf. This cruise also had the unique opportunity to retrieve deep cores from the Shimokita coal bed system in Japan with the aseptic and anaerobic conditions necessary to look for deep life. Onboard scientists prepared nearly 1,700 microbiology samples shared among five different countries to study life in the deep biosphere. Samples spanned over 1 km in sampling depths and include representatives of shale, sandstone, and coal lithologies. Findings from previous IODP and deep mine expeditions suggest the genetic potential for methylotrophy in the deep subsurface, but it has yet to be observed in incubations. A subset of Expedition 337 anoxic incubations were prepared with a range of 13C-methyl substrates (methane, methylamine, and methanol) and maintained near in situ temperatures. To observe 13C methyl compound metabolism over time, we monitored the δ13C of the dissolved inorganic carbon (by-product of methyl compound metabolism) over a period of 1.5 years. Elemental analysis (EA), ion chromatograph (IC), 13C volatile fatty acid (VFA), and mineral-associated microscopy data were also collected to constrain initial and endpoint conditions in these incubations. Our geochemical evidence suggests that the coal horizon incubated with 13C-methane showed the highest activity of all methyl incubations. This provides the first known observation of methane-activated metabolism in the deep biosphere, and suggests there are not only active cells in the deeply buried terrigenous coal bed at Shimokita, but the presence of a microbial community activated by methylotrophic compounds.

Foraminiferal signatures of mass transport from the North-West Continental Shelf off Western Australia, IODP Expedition 356

NASA Astrophysics Data System (ADS)

Mamo, B. L.; McHugh, C.; Renema, W.; Gallagher, S. J.; Fulthorpe, C.; Bogus, K.

2017-12-01

In 2015, International Ocean Discovery Program Expedition 356 cored a transect along the margin off Western Australian to investigate the history of the Indonesian Throughflow (ITF) and its integral role in the development of global thermohaline circulation and climate. Throughout the expedition, a suite of foraminiferal analyses were employed wherein an incredibly diverse benthic fauna ( 260 species) was used to reveal palaeo-water depth, palaeobathymetric setting and variable conditions at the sediment-water interface. Benthic foraminiferal biofacies are particularly sensitive to changes in environmental conditions, have a rapid turnover and are ideal proxies for monitoring physical and chemical changes in marine environments. When this information is combined with lithostratigraphic and other microfossil data, a robust understanding of past environments and past geological events can be reconstructed. Shipboard data were used to isolate horizons of interest for more intense sampling at Site U1461, situated on the Northwest Shelf (127 m water depth). The shipboard data revealed a large ( 150 m-thick) turbidite horizon hosting benthic foraminifera from a substantially shallower water depth than the horizon immediately preceding. We present preliminary foraminiferal results combined with shipboard sedimentological descriptions to better constrain the deposit's occurrence in the biostratigraphic record, use benthic foraminifera to elucidate the deposit's sedimentary origins and link this event with others in the region to investigate potential catalysts for its deposition.

Exploring the Oceans With OOI and IODP: A New Partnership in Education and Outreach

NASA Astrophysics Data System (ADS)

Gröschel, H.; Robigou, V.; Whitman, J.; Jagoda, S. K.; Randle, D.

2003-12-01

The Ocean Observatories Initiative (OOI), a new program supported by the National Science Foundation (NSF), will investigate ocean and Earth processes using deep-sea and coastal observatories, as well as a lithospheric plate-scale cabled observatory that spans most of the geological and oceanographic processes of our planet. October 2003 marked the beginning of the Integrated Ocean Drilling Program (IODP), the third phase of a scientific ocean drilling effort known for its international cooperation, multidisciplinary research, and technological innovation. A workshop exploring the scientific, technical, and educational linkages between OOI and IODP was held in July 2003. Four scientific thematic groups discussed and prioritized common goals of the two programs, and identified experiments and technologies needed to achieve these objectives. The Education and Outreach (E&O) group attended the science sessions and presented seed ideas on activities for all participants to discuss and evaluate. A multidisciplinary dialogue between E&O facilitators, research scientists, and technology specialists was initiated. OOI/IODP participants support the recommendation of the IODP Education Workshop (May 2003) that the IODP and US Science Support Program (USSSP)-successor program have clear commitments to education and outreach. Specific organizational recommendations for OOI/IODP are: (1) E&O should have equal status with science and engineering in the OOI management/planning structure, and enjoy adequate staffing at a US program office; (2) an E&O Advisory Committee of scientists, engineers, technology experts, and educators should be established to develop and implement a viable, vibrant E&O plan; (3) E&O staff and advisors should (a) provide assistance to researchers in fulfilling E&O proposal requirements from preparation to review stages, (b) promote submittal of proposals to government agencies specifically for OOI/IODP-related E&O activities, and (c) identify and foster partners, networks, and funding opportunities. Specific E&O strategies include: (1) present observatory science and ocean drilling content, and the sense of discovery and international cooperation unique to OOI/IODP, to a broad audience; (2) develop and maintain an effective website with distinct resources for K-20 educators, students, and the public; (3) provide pre-service, in-service, and in-residence programs for K-12 teachers that are synergistic with national and local education standards; (4) focus K-12 education efforts on middle school students in grades 5-8; (5) continue and expand existing, successful Ocean Drilling Program activities for undergraduate and graduate students and educators; and (6) try to avoid redundancy with existing E&O efforts within the ocean sciences community by adopting successful models and exploring partnership opportunities with other NSF-funded ocean science education centers and initiatives.

Microbial diversity in Cenozoic sediments recovered from the Lomonosov Ridge in the Central Arctic basin.

PubMed

Forschner, Stephanie R; Sheffer, Roberta; Rowley, David C; Smith, David C

2009-03-01

The current understanding of microbes inhabiting deeply buried marine sediments is based largely on samples collected from continental shelves in tropical and temperate latitudes. The geographical range of marine subsurface coring was expanded during the Integrated Ocean Drilling Program Arctic Coring Expedition (IODP ACEX). This expedition to the ice-covered central Arctic Ocean successfully cored the entire 428 m sediment stack on the Lomonosov Ridge during August and September 2004. The recovered cores vary from siliciclastic sediment low in organic carbon (< 0.2%) to organic rich ( approximately 3%) black sediments that rapidly accumulated in the early middle Eocene. Three geochemical environments were characterized based on chemical analyses of porewater: an upper ammonium oxidation zone, a carbonate dissolution zone and a deep (> 200 m below sea floor) sulfate reduction zone. The diversity of microbes within each zone was assessed using 16S rRNA phylogenetic markers. Bacterial 16S rRNA genes were successfully amplified from each of the biogeochemical zones, while archaea was only amplified from the deep sulfate reduction zone. The microbial communities at each zone are phylogenetically different and are most closely related to those from other deep subsurface environments.

Between land and sea: divergent data stewardship practices in deep-sea biosphere research

NASA Astrophysics Data System (ADS)

Cummings, R.; Darch, P.

2013-12-01

Data in deep-sea biosphere research often live a double life. While the original data generated on IODP expeditions are highly structured, professionally curated, and widely shared, the downstream data practices of deep-sea biosphere laboratories are far more localized and ad hoc. These divergent data practices make it difficult to track the provenance of datasets from the cruise ships to the laboratory or to integrate IODP data with laboratory data. An in-depth study of the divergent data practices in deep-sea biosphere research allows us to: - Better understand the social and technical forces that shape data stewardship throughout the data lifecycle; - Develop policy, infrastructure, and best practices to improve data stewardship in small labs; - Track provenance of datasets from IODP cruises to labs and publications; - Create linkages between laboratory findings, cruise data, and IODP samples. In this paper, we present findings from the first year of a case study of the Center for Dark Energy Biosphere Investigations (C-DEBI), an NSF Science and Technology Center that studies life beneath the seafloor. Our methods include observation in laboratories, interviews, document analysis, and participation in scientific meetings. Our research uncovers the data stewardship norms of geologists, biologists, chemists, and hydrologists conducting multi-disciplinary research. Our research team found that data stewardship on cruises is a clearly defined task performed by an IODP curator, while downstream it is a distributed task that develops in response to local need and to the extent necessary for the immediate research team. IODP data are expensive to collect and challenging to obtain, often costing $50,000/day and requiring researchers to work twelve hours a day onboard the ships. To maximize this research investment, a highly trained IODP data curator controls data stewardship on the cruise and applies best practices such as standardized formats, proper labeling, and centralized storage. In the laboratory, a scientist is his or her own curator. In contrast to the IODP research parties, laboratory research teams analyze diverse datasets, share them internally, implement ad hoc data management practices, optimize methods for their specific research questions, and release data on request through personal transactions. We discovered that while these workflows help small research teams retain flexibility and local control - crucial in exploratory deep-sea biosphere research - they also hinder data interoperability, discoverability, and consistency of methods from one research team to the next. Additional consequences of this contrast between IODP and lab practices are that it is difficult to track the provenance of data and to create linkages between laboratory findings, cruise data, and archived IODP samples. The ability to track provenance would add value to datasets and provide a clearer picture of the decisions made throughout the data lifecycle. Better linkages between the original data, laboratory data, and samples would allow secondary researchers to locate IODP data that may be useful to their research after laboratory findings are published. Our case study is funded by the Sloan Foundation and NSF.

IN-SITU SAMPLING AND CHARACTERIZATION OF NATURALLY OCCURRING MARINE METHANE HYDRATE USING THE D/V JOIDES RESOLUTION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Frank R. Rack; Peter Schultheiss; Melanie Holland

The primary accomplishments of the JOI Cooperative Agreement with DOE/NETL in this quarter were that: (1) follow-up logging of pressure cores containing hydrate-bearing sediment; and (2) opening of some of these cores to establish ground-truth understanding. The follow-up measurements made on pressure cores in storage are part of a hydrate geriatric study related to ODP Leg 204. These activities are described in detail in Appendices A and B of this report. Work also continued on developing plans for Phase 2 of this cooperative agreement based on evolving plans to schedule a scientific ocean drilling expedition to study marine methane hydratesmore » along the Cascadia margin, in the NE Pacific as part of the Integrated Ocean Drilling Program (IODP) using the R/V JOIDES Resolution.« less

Tectonic evolution of the outer Izu-Bonin-Mariana fore arc system: initial results from IODP Expedition 352

NASA Astrophysics Data System (ADS)

Kurz, W.; Ferre, E. C.; Robertson, A. H. F.; Avery, A. J.; Kutterolf, S.

2015-12-01

During International Ocean Discovery Program (IODP) Expedition 352, a section through the volcanic stratigraphy of the outer fore arc of the Izu-Bonin-Mariana (IBM) system was drilled to trace magmatism, tectonics, and crustal accretion associated with subduction initiation. Structures within drill cores, borehole and site survey seismic data indicate that tectonic deformation in the outer IBM fore arc is mainly post-magmatic. Extension generated asymmetric sediment basins such as half-grabens at sites 352-U1439 and 352-U1442 on the upper trench slope. Along their eastern margins the basins are bounded by west-dipping normal faults. Deformation was localized along multiple sets of faults, accompanied by syn-tectonic pelagic and volcaniclastic sedimentation. The lowermost sedimentary units were tilted eastward by ~20°. Tilted beds were covered by sub-horizontal beds. Biostratigraphic constraints reveal a minimum age of the oldest sediments at ~ 35 Ma; timing of the sedimentary unconformities is between ~ 27 and 32 Ma. At sites 352-U1440 and 352-U1441 on the outer fore arc strike-slip faults are bounding sediment basins. Sediments were not significantly affected by tectonic tilting. Biostratigraphy gives a minimum age of the basement-cover contact between ~29.5 and 32 Ma. The post-magmatic structures reveal a multiphase tectonic evolution of the outer IBM fore arc. At sites 352-U1439 and 352-U1442, shear with dominant reverse to oblique reverse displacement was localized along subhorizontal fault zones, steep slickensides and shear fractures. These were either re-activated as or cut by normal-faults and strike-slip faults. Extension was also accommodated by steep to subvertical mineralized veins and extensional fractures. Faults at sites 352-U1440 and 352-U1441 show mainly strike-slip kinematics. Sediments overlying the igneous basement(maximum Late Eocene to Recent age), document ash and aeolian input, together with mass wasting of the fault-bounded sediment ponds.

Geological Development of the Izu-Bonin Forearc Since the Eocene Based on Biostratigraphic, Rock Magnetic, and Sediment Provenance Observations from IODP Expedition 352 Drill Cores

NASA Astrophysics Data System (ADS)

Petronotis, K. E.; Robertson, A.; Kutterolf, S.; Avery, A.; Baxter, A.; Schindlbeck, J. C.; Wang, K. L.; Acton, G.

2016-12-01

International Ocean Discovery Program (IODP) Expedition 352 recovered early Oligocene to recent sediments above Eocene igneous basement at 4 sites in the Izu-Bonin Forearc. The sites were selected to investigate the forearc region since subduction initiation in the Eocene, with Sites U1439 and U1442 being cored into the upper trench slope and Sites U1440 and U1441 into the lower trench slope. Postcruise studies of biostratigraphy, sediment chemistry, tephra composition and chronology and magnetic properties, along with observations from prior coring help constrain the regional geological development. Volcanic activity in the area, as inferred from its influence on sediment composition, has varied between long periods of activity and quiescence. Combined whole-rock sediment chemistry and tephra compositions suggest that during the Oligocene to earliest Miocene ( 30-22 Ma) tuffaceous input of predominantly dacitic composition was mainly derived from the intra-oceanic Izu-Bonin Arc. The early Miocene interval ( 22-15 Ma) lacks tuffaceous input, as supported by rock magnetic data. During this period, the forearc subsided beneath the carbonate compensation depth (CCD), as evidenced by radiolarian-bearing mud and metal-rich silty clay. This was followed by input of tephra with bimodal felsic and mafic compositions from the Izu-Bonin Arc from 15 to 5 Ma. Middle Miocene to Quaternary time was characterized by increased carbonate preservation, coupled with abundant, predominantly felsic tephra input, which is chemically indicative of a Japan continental arc source (Honshu), with additional chemically distinctive input from the Izu-Bonin Arc. Extending back to 32 Ma, tephra layers can be correlated between the upper-slope sites, extrapolated to the less well-dated lower-slope sites, and further correlated with onland Japanese tephra (Kutterolf et al., 2016; Goldschmidt Conference). Overall, the new results provide an improved understanding of the regional tectonic evolution.

Seismic inversion for incoming sedimentary sequence in the Nankai Trough margin off Kumano Basin, southwest Japan

NASA Astrophysics Data System (ADS)

Naito, K.; Park, J.

2012-12-01

The Nankai Trough off southwest Japan is one of the best subduction-zone to study megathrust earthquake mechanism. Huge earthquakes have been repeated in the cycle of 100-150 years in the area, and in these days the next emergence of the earthquake becomes one of the most serious issue in Japan. Therefore, detailed descriptions of geological structure are urgently needed there. IODP (Integrated Ocean Drilling Program) have investigated this area in the NanTroSEIZE science plan. Seismic reflection, core sampling and borehole logging surveys have been executed during the NanTroSEIZE expeditions. Core-log-seismic data integration (CLSI) is useful for understanding the Nankai seismogenic zone. We use the seismic inversion method to do the CLSI. The seismic inversion (acoustic impedance inversion, A.I. inversion) is a method to estimate rock physical properties using seismic reflection and logging data. Acoustic impedance volume is inverted for seismic data with density and P-wave velocity of several boreholes with the technique. We use high-resolution 3D multi-channel seismic (MCS) reflection data obtained during KR06-02 cruise in 2006, and measured core sample properties by IODP Expeditions 322 and 333. P-wave velocities missing for some core sample are interpolated by the relationship between acoustic impedance and P-wave velocity. We used Hampson-Russell software for the seismic inversion. 3D porosity model is derived from the 3D acoustic impedance model to figure out rock physical properties of the incoming sedimentary sequence in the Nankai Trough off Kumano Basin. The result of our inversion analysis clearly shows heterogeneity of sediments; relatively high porosity sediments on the shallow layer of Kashinosaki Knoll, and distribution of many physical anomaly bands on volcanic and turbidite sediment layers around the 3D MCS survey area. In this talk, we will show 3D MCS, acoustic impedance, and porosity data for the incoming sedimentary sequence and discuss its possible implications for the Nankai seismogenic behavior.

Recent scientific and operational achievements of D/V Chikyu

NASA Astrophysics Data System (ADS)

Taira, Asahiko; Toczko, Sean; Eguchi, Nobu; Kuramoto, Shin'ichi; Kubo, Yusuke; Azuma, Wataru

2014-12-01

The D/V Chikyu, a scientific drilling vessel, is equipped with industry-standard riser capabilities. Riser drilling technology enables remarkable drilling and downhole logging capabilities and provides unprecedented hole-stability, enabling the shipboard team to retrieve high-quality wire-line logging data as well as well-preserved core samples. The 11 March 2011 Tohoku Oki mega-earthquake and tsunami cost over 18,000 casualties in NE Japan. Chikyu, docked in the Port of Hachinohe, was damaged by the tsunami. By April 2012, the ship was back in operation; drilling the toe of the Japan Trench fault zone where topographic surveys suggested there was up to 50 m eastward motion, the largest earthquake rupture ever recorded. During Integrated Ocean Drilling Program (IODP) Expeditions 343 and 343 T, Chikyu drilled 850 m below sea floor (mbsf) in 6,900+ m water depth and recovered core samples of a highly brecciated shear zone composed of pelagic claystone. A subseafloor observatory looking for temperature signatures caused by the fault friction during the earthquake, was installed and later successfully recovered. The recovered temperature loggers recorded data from which the level of friction during the mega-earthquake slip could be determined. Following Exp. 343, Chikyu began IODP Exp. 337, a riser drilling expedition into the Shimokita coal beds off Hachinohe, to study the deep subsurface biosphere in sedimentary units including Paleogene-Neogene coal beds. New records in scientific ocean drilling were achieved in deepest penetration (drilling reached 2,466 mbsf) and sample recovery. Currently Chikyu is conducting deep riser drilling at the Nankai Trough in the final stage of the NanTroSEIZE campaign. During the years 2011 to 2013, including drilling in the Okinawa Hydrothermal System, Chikyu's operational and scientific achievements have demonstrated that the ship's capabilities are vital for opening new frontiers in earth and biological sciences.

Facies And Bedding Analysis of Deep-Marine, Arc-Related, Sediementary Rocks Cored on International Ocean Drilling Program Expedition 351.

NASA Astrophysics Data System (ADS)

Johnson, K. E.; Marsaglia, K. M.

2015-12-01

The Izu-Bonin-Mariana (IBM) Arc System, south of Japan, hosts a multitude of active and extinct (remnant) arc volcanic sediment sources. Core extracted adjacent to the proto-IBM arc (Kyushu-Palau Ridge; KPR) in the Amami-Sankaku Basin on International Ocean Discovery Program (IODP) Expedition 351 contains evidence of the variety of sediment sources that have existed in the area as a result of changing tectonic regimes through arc development, backarc basin formation and remnant arc abandonment. Approximately 1000 meters of Eocene to Oligocene volcaniclastic sedimentary rocks were analyzed via shipboard core photos, core descriptions, and thin sections with the intention of understanding the depositional history at this site. These materials contain a crucial record of arc development complementary to the Neogene history preserved in the active reararc (Expedition 350) and compressed whole-arc record in the current forearc (Expedition 352). A database of stratigraphic columns was created to display grain size trends, facies changes, and bedding characteristics. Individual beds (depositional events) were classified using existing and slightly modified classification schemes for muddy, sandy and gravel-rich gravity flow deposits, as well as muddy debris flows and tuffs. Utilizing the deep marine facies classes presented by Pickering et al. (1986), up section changes are apparent. Through time, as the arc developed, facies and bedding types and their proportions change dramatically and relatively abruptly. Following arc initiation facies are primarily mud-rich with intercalated tuffaceous sand. In younger intervals, sand to gravel gravity-flow deposits dominate, becoming more mud-rich. Muddy gravity flow deposits, however, dominate farther upsection. The overall coarsening-upward pattern (Unit III) is consistent with building of the arc edifice. Farther upsection (Unit II) an abrupt fining-upward trend represents the onset of isolation of the KPR as backarc spreading in the Shikoku Basin was initiated. This information will be combined with volcanic provenance and geochemical information from other studies, ultimately creating a deep-marine facies model for intraoceanic arc systems.

Non-destructive X-ray Computed Tomography (XCT) Analysis of Sediment Variance in Marine Cores

NASA Astrophysics Data System (ADS)

Oti, E.; Polyak, L. V.; Dipre, G.; Sawyer, D.; Cook, A.

2015-12-01

Benthic activity within marine sediments can alter the physical properties of the sediment as well as indicate nutrient flux and ocean temperatures. We examine burrowing features in sediment cores from the western Arctic Ocean collected during the 2005 Healy-Oden TransArctic Expedition (HOTRAX) and from the Gulf of Mexico Integrated Ocean Drilling Program (IODP) Expedition 308. While traditional methods for studying bioturbation require physical dissection of the cores, we assess burrowing using an X-ray computed tomography (XCT) scanner. XCT noninvasively images the sediment cores in three dimensions and produces density sensitive images suitable for quantitative analysis. XCT units are recorded as Hounsfield Units (HU), where -999 is air, 0 is water, and 4000-5000 would be a higher density mineral, such as pyrite. We rely on the fundamental assumption that sediments are deposited horizontally, and we analyze the variance over each flat-lying slice. The variance describes the spread of pixel values over a slice. When sediments are reworked, drawing higher and lower density matrix into a layer, the variance increases. Examples of this can be seen in two slices in core 19H-3A from Site U1324 of IODP Expedition 308. The first slice, located 165.6 meters below sea floor consists of relatively undisturbed sediment. Because of this, the majority of the sediment values fall between 1406 and 1497 HU, thus giving the slice a comparatively small variance of 819.7. The second slice, located 166.1 meters below sea floor, features a lower density sediment matrix disturbed by burrow tubes and the inclusion of a high density mineral. As a result, the Hounsfield Units have a larger variance of 1,197.5, which is a result of sediment matrix values that range from 1220 to 1260 HU, the high-density mineral value of 1920 HU and the burrow tubes that range from 1300 to 1410 HU. Analyzing this variance allows us to observe changes in the sediment matrix and more specifically capture where, and to what extent, the burrow tubes deviate from the sediment matrix. Future research will correlate changes in variance due to bioturbation to other features indicating ocean temperatures and nutrient flux, such as foraminifera counts and oxygen isotope data.

Quantitative Characterization of Chicxulub Impact Basin Peak Ring Materials

NASA Astrophysics Data System (ADS)

King, B.; Nixon, C.; Kofman, R.; Schmitt, D. R.

2017-12-01

The exceptionally low seismic wave speeds determined by tomographic image models of the upper portions of the peak ring of the Chicxulub Impact Structure were largely confirmed by sonic and seismic borehole measurements from the IODP/ICDP Expedition 364 scientific drilling campaign. These low wave speeds result from the extensive damage to the peak ring rocks that, based on the results of numerical modelling, were likely displaced 20 km outwards and 10 km upwards after being subject to initial shock pressures as high as 60 GPa. Here, we describe a series of detailed petrophysical and wave speed measurements on select `granite' and `impact melt' cores from the borehole in order to better understand the nature of this damage To date, two granite and two impact melt samples have been studied. X-ray CT scans (30 mm voxel) reveal extensive micro-fracturing between and within the mineral grains in the granites (Fig. 1a) while highlighting the existence of relatively large, 1000 mm3, occluded pores (Fig. 1b). The porosities, as determined using a Hg-injection porosimeter, were also remarkably high with values of <10% and <25% observed in the granites and the melts, respectively. Grain densities, measured using a helium pycnometer, were similar between both samples ranging between 2.581-2.654 g/cc. Both VP and VS were determined under hydrostatic confining pressures between 3 MPa and 200 MPa by ultrasonic transit time measurements (Fig. 1c). The velocities increase linearly with pressure in the impact melt rock suggesting this material lacks microcrack porosity. In contrast, the velocities in the granites depend strongly on pressure further indicating the existence of pervasive microcracking. Even at the highest confining pressure of 200 MPa available to us, the observed VP is 4.5 km/s, a value much below the 6.0 km/s expected for the same nonporous rock. These observations suggest that the low wave speeds and densities within the peak ring differ based on whether the material is the original displaced granite or the intruded impact melt. Samples and data provided by IODP. Samples can be requested at http://web.iodp.tamu.edu/sdrm after 19 October 2017. Expedition 364 was funded by ECORD, IODP and ICDP with contributions and logistical support from the Yucatan State Government and Universidad Nacional Autónoma de México (UNAM).

Operations Summary During Riserless Drilling to >7700 mbsl in the Japan Trench for IODP Expedition 343 & 343T: JFAST, and Discussion of the Relationship Between Drilling Parameters and Rock Damage.

NASA Astrophysics Data System (ADS)

Toy, V. G.; Maeda, L.; Toczko, S.; Eguchi, N.; Chester, F. M.; Mori, J. J.; Sawada, I.; Saruhashi, T.

2014-12-01

During IODP Expedition 343: The Japan Trench Fast Drilling Project (JFAST), two main boreholes were drilled from the D/V Chikyu in ~7000 m water depth. An uncored hole that penetrated to 850.5 meters below seafloor (mbsf) (total depth [TD] = 7740 meters below sea level [mbsl]) was documented using logging while drilling (LWD) tools. From an adjacent partially cored hole drilled to 844.5 mbsf (TD = 7734 mbsl) 21 cores were acquired that spanned the two main fault targets. The operations lasted 88 days. The drilling operation was very technically challenging. The drill string had to be withdrawn a number of times due to high seas, and technical issues; five holes were drilled (one abandoned after spud-in) and reoccupied in >6800 m water depth. A simple observatory was deployed in the wellhead installed during Exp 343 during the follow-up Exp 343T. In certain intervals during coring we mostly recovered loose, subrounded fine gravel clasts of the two major lithologies penetrated to those depths (silt and mudstones). We have performed particle shape and size analysis on these gravel aggregates. Particle shape variations apparent visually are not clearly quantified by conventional 'shape descriptors'. Variations in particle size distributions are apparent and we will discuss whether these relate to variations in drilling parameters.

Numerical simulations of groundwater flow at New Jersey Shallow Shelf

NASA Astrophysics Data System (ADS)

Fehr, Annick; Patterson, Fabian; Lofi, Johanna; Reiche, Sönke

2016-04-01

During IODP Expedition 313, three boreholes were drilled in the so-called New Jersey transect. Hydrochemical studies revealed the groundwater situation as more complex than expected, characterized by several sharp boundaries between fresh and saline groundwater. Two conflicting hypotheses regarding the nature of these freshwater reservoirs are currently debated. One hypothesis is that these reservoirs are connected with onshore aquifers and continuously recharged by seaward-flowing groundwater. The second hypothesis is that fresh groundwater was emplaced during the last glacial period. In addition to the petrophysical properties measured during IODP 313 expedition, Nuclear Magnetic Resonance (NMR) measurements were performed on samples from boreholes M0027, M0028 and M0029 in order to deduce porosities and permeabilities. These results are compared with data from alternative laboratory measurements and with petrophysical properties inferred from downhole logging data. We incorporate these results into a 2D numerical model that reflects the shelf architecture as known from drillings and seismic data to perform submarine groundwater flow simulations. In order to account for uncertainties related to the spatial distribution of physical properties, such as porosity and permeability, systematic variation of input parameters was performed during simulation runs. The target is to test the two conflicting hypotheses of fresh groundwater emplacements offshore New Jersey and to improve the understanding of fluid flow processes at marine passive margins.

Beyond 2013 - The Future of European Scientific Drilling Research - An introduction.

NASA Astrophysics Data System (ADS)

Camoin, G.; Stein, R.

2009-04-01

The Integrated Ocean Drilling Program (IODP) is funded for the period 2003-2013, and is now starting to plan the future of ocean drilling beyond 2013, including the development of new technologies, new emerging research fields as and the societal relevance of this programme. In this context an interdisciplinary and multinational (USA, Europe, Japan, Asian and Oceanian countries), key conference - INVEST IODP New Ventures in Exploring Scientific Targets - addressing all international IODP partners is therefore planned for September 23rd-25th 2009 in Bremen, Germany (more information at http://www.iodp.org and http://marum.de/iodp-invest.html) to discuss future directions of ocean drilling research and related aspects such as ventures with related programmes or with industry. The first critical step of INVEST is to define the scientific research goals of the second phase of the Integrated Ocean Drilling Program (IODP), which is expected to begin in late 2013. INVEST will be open to all interested scientists and students and will be the principal opportunity for the international science community to help shape the future of scientific ocean drilling. The outcome of the conference will be the base to draft a science plan in 2010 and to define new goals and strategies to effectively meet the challenges of society and future ocean drilling. The current EGU Session and the related two days workshop which will be held at the University of Vienna will specifically address the future of European scientific drilling research. The major objectives of those two events are to sharpen the European interests in the future IODP and to prepare the INVEST Conference and are therefore of prime importance to give weight to the European propositions in the program renewal processes, both on science, technology and management, and to provide the participants with information about the status/process of ongoing discussions and negotiations regarding program structure, and provide them with the expected framework (available drilling platforms and anticipated funding levels). The key items that should be addressed during the EGU Session and the workshop will especially include : (1) The future of ECORD (science, technology, management). (2) New research initiatives and emerging fields in scientific drilling (3) Relationships between IODP and other programs (e.g. ICDP, IMAGES etc). (4) Collaboration between academia and industry. (5) New technologies and the Mission Specific Platform approach.

Ocean Drilling Program: Public Information

Science.gov Websites

IODP planning for post-2003 research Sites related to ODP Merchandise with ODP logo Free brochures are available for free. For more information, please contact webmaster@iodp.tamu.edu or browse the

Magma Differentiation Processes That Develop an "Enriched" Signature in the Izu Bonin Rear Arc: Evidence from Drilling at IODP Site U1437

NASA Astrophysics Data System (ADS)

Heywood, L. J.; DeBari, S. M.; Schindlbeck, J. C.; Escobar-Burciaga, R. D.

2015-12-01

The Izu Bonin rear arc represents a unique laboratory to study the development of continental crust precursors at an intraoceanic subduction zone., Volcanic output in the Izu Bonin rear arc is compositionally distinct from the Izu Bonin main volcanic front, with med- to high-K and LREE-enrichment similar to the average composition of the continental crust. Drilling at IODP Expedition 350 Site U1437 in the Izu Bonin rear arc obtained volcaniclastic material that was deposited from at least 13.5 Ma to present. IODP Expedition 350 represents the first drilling mission in the Izu Bonin rear arc region. This study presents fresh glass and mineral compositions (obtained via EMP and LA-ICP-MS) from unaltered tephra layers in mud/mudstone (Lithostratigraphic Unit I) and lapillistone (Lithostratigraphic Unit II) <4.5 Ma to examine the geochemical signature of Izu Bonin rear arc magmas. Unit II samples are coarse-grained tephras that are mainly rhyolitic in composition (72.1-77.5 wt. % SiO2, 3.2-3.9 wt. % K2O and average Mg# 24) and LREE-enriched. These rear-arc rhyolites have an average La/Sm of 2.6 with flat HREEs, average Th/La of 0.15, and Zr/Y of 4.86. Rear-arc rhyolite trace element signature is distinct from felsic eruptive products from the Izu Bonin main volcanic front, which have lower La/Sm and Th/La as well as significantly lower incompatible element concentrations. Rear arc rhyolites have similar trace element ratios to rhyolites from the adjacent but younger backarc knolls and actively-extending rift regions, but the latter is typified by lower K2O, as well as a smaller degree of enrichment in incompatible elements. Given these unique characteristics, we explore models for felsic magma formation and intracrustal differentiation in the Izu Bonin rear arc.

Isotope Biogeochemistry of Sulfur in a Cold-Water Carbonate Mound (IODP Site 1317)

NASA Astrophysics Data System (ADS)

Ferdelman, T. G.; Boettcher, M. E.

2007-12-01

To establish a depositional model for cold-water carbonate mounds, Challenger Mound and adjacent continental slope sites were drilled during IODP Expedition 307 in May 2005. Although a role for methane seepage and subsequent anaerobic oxidation was discounted both as a hard-round substrate for mound initiation and as a principal source of carbonate within the mound succession, interstitial water profiles of sulfate, alkalinity, Mg, and Sr indicated a tight coupling between carbonate diagenesis and mircrobial sulfate reduction. The reaction of sulfide with siliciclastic iron-bearing minerals to form pyrite was proposed to account for enhanced diagenetic carbonate precipitation (Ferdelman et al., 2006; Proc. IODP, vol. 307; doi:10.2204/iodp.proc.307.2006). To characterize these geomicrobial sulfur transformations in the carbonate mound sediments, the inorganic and stable isotope geochemical compositions of pore water sulfate and solid phase reduced sulfur compounds were performed. Acid-volatile sulfur (AVS) and pyrite del 34S compositions were usually similar and exhibited an increasing trend of from -40 per mil near surface to -20 per mil at the mound base at 132 mbsf. However, several excursions to more 34S sulfur enriched pyrite to values >0 per mil were observed in the deeper sections of the mound sequence. These excursions may be linked transitory changes in the depth of the methane-sulfate transition zone during mound build-up. The oxygen isotopic composition of residual dissolved sulfate indicates intracellular isotope exchange processes within the cells of SRBs, leading to increasing equilibration between extracellular pore water and sulfate.

The ICTJA-CSIC Science Week 2016: an open door to Earth Sciences for secondary education students

NASA Astrophysics Data System (ADS)

Cortes-Picas, Jordi; Diaz, Jordi; Fernandez-Turiel, Jose-Luis; Garcia-Castellanos, Daniel; Geyer, Adelina; Jurado, Maria-Jose; Montoya, Encarni; Rejas Alejos, Marta; Sánchez-Pastor, Pilar; Valverde-Perez, Angel

2017-04-01

The Science Week is one of the main scientific outreach events every year in Spain. The Institute of Earth Sciences Jaume Almera of CSIC (ICTJA-CSIC) participates in it since many years ago, opening its doors and proposing several activities in which it is shown what kind of multidisciplinary research is being developed at the Institute and in Geosciences. The activities,developed as workshops, are designed and conducted by scientific and technical personnel of the centre, who participates in the Science Week voluntarily. The activities proposed by the ICTJA-CSIC staff are designed for a target audience composed by secondary school students (12-18 years). The ICTJA-CSIC joined Science Week 2016 in the framework of the activity entitled "What we investigate in Earth Sciences?". The aim is to show to the society what is being investigated in the ICTJA-CSIC. In addition, it is intended, with the contact and interaction between the public and the institute researchers, to increase the interest in scientific activity and, if possible, to generate new vocations in the field of the Earth Sciences among secondary school pupils. We show in this communication the experience of the Science Week 2016 at the ICTJA-CSIC, carried out with the effort and commitment of the of the Institute's personnel with the outreach of Earth Sciences research. Between November 14th and 19th 2016, more than 100 students from four secondary schools from Barcelona area visited the Institute and took part in the Science Week. A total of six interactive workshops were prepared showing different features of seismology, geophysical borehole logging, analog and digital modelling, paleoecology, volcanology and geochemistry. As a novelty, this year a new workshop based on an augmented reality sandbox was offered to show and to simulate the processes of creation and evolution of the topographic relief. In addition, within the workshop dedicated to geophysical borehole logging, six exact replicates of sediment cores from outstanding expeditions of the Ocean Drilling Program (ODP) and the International Ocean Discovery Program IODP (IODP) were shown to the visitors. We acknowledge the collaboration of ODP and IODP programs and the FECYT in the development of the Science Week 2016 at ICTJA-CSIC.

Virtual Research Expeditions along Plate Margins: Examples from an Online Oceanography Course

NASA Astrophysics Data System (ADS)

Reed, D. L.; Moore, G. F.; Bangs, N. L.; Tobin, H. J.

2010-12-01

An undergraduate online course in oceanography is based on the participation of each student in a series of virtual, at-sea, research expeditions, two of which are used to examine the tectonic processes at plate boundaries. The objective is to leverage the results of major federal research initiatives in the ocean sciences into effective learning tools with a long lifespan for use in undergraduate geoscience courses. These web-based expeditions examine: (1) hydrothermal vents along the divergent plate boundary at the Explorer Ridge and (2) the convergent plate boundary fault along the Nankai Trough, which is the objective of the multi-year NanTroSEIZE drilling program. Here we focus on the convergent plate boundary in NanTroSEIZE 3-D, which is based on a seismic survey supported through NSF-MARGINS, IODP and CDEX in Japan to study the properties of the plate boundary fault system in the upper limit of the seismogenic zone off Japan. The virtual voyage can be used in undergraduate classes at anytime, since it is not directly tied to the finite duration of a specific seagoing project, and comes in two versions, one that is being used in geoscience major courses and the other in non-major courses, such as the oceanography course mentioned above and a lower-division global studies course with a science emphasis. NanTroSEIZE in 3-D places undergraduate learning in an experiential framework as students participate on the expedition and carry out research on the structure of the plate boundary fault. Students learn the scientific background of the program, especially the critical role of international collaboration, and meet the chief scientists before joining the 3-D seismic imaging expedition to identify the active faults that were the likely sources of devastating earthquakes and tsunamis in Japan in 1944 and 1948. The initial results of phase I ODP drilling that began in 2007 are also reviewed. Students document their research on a worksheet that accompanies the expedition, interpret a slice through the 3-D seismic volume, and compose an “AGU-style” abstract summarizing their work, which is submitted to the instructor for review. NanTroSEIZE in 3-D is openly available and can be accessed through the MARGINS Mini-lesson section of the Science Education Resource Center (SERC).

An initial examination of carbonate production in the western equatorial Pacific: XRF results from the Pliocene-Pleistocene of IODP Site U1490

NASA Astrophysics Data System (ADS)

Chapman, J.; Kulhanek, D. K.; Rosenthal, Y.; Holbourn, A. E.

2017-12-01

International Ocean Discovery Program (IODP) Expedition 363 sought to determine the nature of and driving forces behind climate variability in the Western Pacific Warm Pool (WPWP) region throughout the Neogene on millennial, orbital, and geologic timescales. Our research focuses on the Pliocene to recent (4-0 Ma) sediment record from IODP Site U1490 to examine changes in carbonate production and burial in the WPWP as a record of variations in the regional/global carbon cycle. This interval is of particular interest because it spans the Middle Pliocene Warm Period, the initiation of Northern Hemisphere Glaciation, and the Mid-Pleistocene Transition. Site U1490 is located on the northern edge of Eauripik Rise at 05°58.95'N, 142°39.27'E in the northern part of the WPWP. At 2341 m water depth, today the site is bathed in Upper Circumpolar Deepwater. Pliocene to recent sediment primarily consists of foraminifer-rich nannofossil ooze, with the sedimentation rate varying between 1.5 and 3 cm/kyr. Initial shipboard measurement of calcium carbonate content shows little variation at low resolution (1 sample every few meters), varying between 90 and 95 wt%. We collected X-ray fluorescence (XRF) data at 2 cm resolution along the composite stratigraphic section to obtain a qualitative measure of the bulk chemistry of the sediment. We will use the weight percent calcium carbonate of discrete samples to calibrate the XRF data to generate a high-resolution carbonate record. We observe cyclical variations in the Ca/Ba, which may reflect variations in productivity and/or dissolution through this interval, although additional work is needed to fully interpret these data. Ultimately our research will allow for comparison between records obtained from these cores located in the western equatorial Pacific to those obtained in the eastern and central Pacific, which will better elucidate the nature of the carbon system during the Plio-Pleistocene.

IODP Expedition 362: Initial results from drilling the Sumatra subduction zone - the role of input materials in shallow seismogenic slip and forearc plateau development

NASA Astrophysics Data System (ADS)

McNeill, L. C.; Dugan, B.; Petronotis, K. E.; Expedition 362 Scientists, I.

2016-12-01

IODP Expedition 362, August-October, 2016, plans to drill two boreholes within the input section of the Indian oceanic plate entering the North Sumatran subduction zone. In 2004, a Mw 9.2 earthquake ruptured the Sunda subduction zone from North Sumatra to the Andaman Islands, a length of 1500 km. The earthquake and tsunami devastated coastal communities around the Indian Ocean. This earthquake and the 2011 Tohoku-Oki Mw 9.0 earthquake showed unexpectedly shallow megathrust slip. In the case of North Sumatra, this shallow slip was focused beneath a distinctive plateau of the accretionary prism. This intriguing seismogenic behavior and forearc structure are not explained by existing models or by observations at other margins where seismogenic slip typically occurs farther landward. Expedition 362 will use core and log data in conjunction with in situ temperature and pressure measurements to document the lithology, structures, and physical and chemical properties of the input sediments. The input materials of the North Sumatran subduction zone are a distinctive, thick (up to 4-5 km) sequence of primarily Bengal-Nicobar Fan-related sediments. This sequence geophysically shows strong evidence for induration and dewatering and has probably reached the temperatures required for sediment-strengthening diagenetic reactions, and input materials may be key to driving the distinctive slip behavior and long-term forearc structure. The plate boundary fault (décollement) originates within the lower pelagic and submarine fan sediments so sampling this interval will help determine what controls décollement development and how its properties evolve. Initial results from the Expedition and plans for post-expedition experiments and modeling will be presented. These methods will be used to predict physical, thermal, fluid, and mechanical properties and diagenetic evolution of the sediments as stresses and temperatures increase due to burial and subduction. Results will be used to test the role of sediment properties in shallow earthquake slip and in the unusual forearc structure. In addition, the results will contribute to our understanding of a) Bengal-Nicobar fan history and records of Himalayan uplift, erosion and monsoon development, and b) stress conditions in a complexly deforming region of the Indian plate.

From vein precipitates to deformation and fluid rock interaction within a SSZ: Insights from the Izu-Bonin-Mariana fore arc

NASA Astrophysics Data System (ADS)

Micheuz, Peter; Quandt, Dennis; Kurz, Walter

2017-04-01

International Ocean Discovery Program (IODP) expeditions 352 and 351 drilled through oceanic crust of the Philippine Sea plate. The two study areas are located near the outer Izu-Bonin-Mariana (IBM) fore arc and in the Amami Sankaku Basin. The primary objective was to improve our understanding of supra-subduction zones (SSZ) and the process of subduction initiation. The recovered drill cores during IODP expedition 352 represent approximately 50 Ma old fore arc basalts (FAB) and boninites revealing an entire volcanic sequence of a SSZ. Expedition 351 drilled FAB like oceanic crust similar in age to the FABs of expedition 352. In this study we present data on vein microstructures, geochemical data and isotopic signatures of vein precipitates to give new insights into fluid flow and precipitation processes and deformation within the Izu-Bonin fore arc. Veins formed predominantly as a consequence of hydrofracturing resulting in the occurrence of branched vein systems and brecciated samples. Along these hydrofractures the amount of altered host rock fragments varies and locally alters the host rock completely to zeolites and carbonates. Subordinately extensional veins released after the formation of the host rocks. Cross-cutting relationships of different vein types point to multiple fracturing events subsequently filled with minerals originating from a fluid with isotopic seawater signature. Based on vein precipitates, their morphology and their growth patterns four vein types have been defined. Major vein components are (Mg-) calcite and various zeolites determined by Raman spectra and electron microprobe analyses. Zeolites result from alteration of volcanic glass during interaction with a seawaterlike fluid. Type I veins which are characterized by micritic infill represent neptunian dykes. They predominantly occur in the upper levels of drill cores being the result of an initial volume change subsequently to crystallization of the host rocks. Type II veins are characterized by blocky carbonates and idiomorphic to blocky zeolites. Blocky carbonates locally exhibit zonation patterns. Type III and type IV veins are both assumed to be extensional veins. Type III is characterized by syntaxial growth and elongate blocky carbonate minerals. They predominantly occur as asymmetric syntaxial veins, locally exhibiting more than one crack-seal event. Type IV veins are defined as antitaxial fibrous carbonates. Type II veins commonly show deformation microstructures like twinning (type I/II twins), slightly curved twins, and subgrain boundaries indicative of incipient plastic deformation. Based on these observations differential stresses around 50 MPa were needed to deform vein minerals, presumably related to IBM fore arc extension due to the retreat of the subducted Pacific plate. We acknowledge financial support by the Austrian Research Fund (P27982-N29) to W. Kurz

Shipboard Analytical Capabilities on the Renovated JOIDES Resolution, IODP Riserless Drilling Vessel

NASA Astrophysics Data System (ADS)

Blum, P.; Foster, P.; Houpt, D.; Bennight, C.; Brandt, L.; Cobine, T.; Crawford, W.; Fackler, D.; Fujine, K.; Hastedt, M.; Hornbacher, D.; Mateo, Z.; Moortgat, E.; Vasilyev, M.; Vasilyeva, Y.; Zeliadt, S.; Zhao, J.

2008-12-01

The JOIDES Resolution (JR) has conducted 121 scientific drilling expeditions during the Ocean Drilling Program (ODP) and the first phase of the Integrated Ocean Drilling Program (IODP) (1983-2006). The vessel and scientific systems have just completed an NSF-sponsored renovation (2005-2008). Shipboard analytical systems have been upgraded, within funding constraints imposed by market driven vessel conversion cost increases, to include: (1) enhanced shipboard analytical services including instruments and software for sampling and the capture of chemistry, physical properties, and geological data; (2) new data management capabilities built around a laboratory information management system (LIMS), digital asset management system, and web services; (3) operations data services with enhanced access to navigation and rig instrumentation data; and (4) a combination of commercial and home-made user applications for workflow- specific data extractions, generic and customized data reporting, and data visualization within a shipboard production environment. The instrumented data capture systems include a new set of core loggers for rapid and non-destructive acquisition of images and other physical properties data from drill cores. Line-scan imaging and natural gamma ray loggers capture data at unprecedented quality due to new and innovative designs. Many instruments used to characterize chemical compounds of rocks, sediments, and interstitial fluids were upgraded with the latest technology. The shipboard analytical environment features a new and innovative framework (DESCinfo) and application (DESClogik) for capturing descriptive and interpretive data from geological sub-domains such as sedimentology, petrology, paleontology, structural geology, stratigraphy, etc. This system fills a long-standing gap by providing a global database, controlled vocabularies and taxa name lists with version control, a highly configurable spreadsheet environment for data capture, and visualization of context data collected with the shipboard core loggers and other instruments.

Ocean Drilling Program: TAMRF Administrative Services: Travel Information

Science.gov Websites

/TAMU web site ODP's main web site Expense Account Instructions Contact: Sharon Gillespie at (979) 845 -8215 or gillespie@iodp.tamu.edu Please see the IODP-USIO travel web site for forms and instructions

Shallow observatory installations unravel earthquake processes in the Nankai accretionary complex (IODP Expedition 365)

NASA Astrophysics Data System (ADS)

Kopf, A.; Saffer, D. M.; Toczko, S.

2016-12-01

NanTroSEIZE is a multi-expedition IODP project to investigate fault mechanics and seismogenesis along the Nankai Trough subduction zone through direct sampling, in situ measurements, and long-term monitoring. Recent Expedition 365 had three primary objectives at a major splay thrust fault (termed the "megasplay") in the forearc: (1) retrieval of a temporary observatory (termed a GeniusPlug) that has been monitoring temperature and pore pressure within the fault zone at 400 meters below seafloor for since 2010; (2) deployment of a complex long-term borehole monitoring system (LTBMS) across the same fault; and (3) coring of key sections of the hanging wall, deformation zone and footwall of the shallow megasplay. Expedition 365 achieved its primary monitoring objectives, including recovery of the GeniusPlug with a >5-year record of pressure and temperature conditions, geochemical samples, and its in situ microbial colonization experiment; and installation of the LTBMS. The pressure records from the GeniusPlug include high-quality records of formation and seafloor responses to multiple fault slip events, including the 2011 M9 Tohoku and the 1 April Mie-ken Nanto-oki M6 earthquakes. The geochemical sampling coils yielded in situ pore fluids from the fault zone, and microbes were successfully cultivated from the colonization unit. The LTBMS incorporates multi-level pore pressure sensing, a volumetric strainmeter, tiltmeter, geophone, broadband seismometer, accelerometer, and thermistor string. This multi-level hole completion was meanwhile connected to the DONET seafloor cabled network for tsunami early warning and earthquake monitoring. Coring the shallow megasplay site in the Nankai forearc recovered ca. 100m of material across the fault zone, which contained indurated silty clay with occasional ash layers and sedimentary breccias in the hangingwall and siltstones in the footwall of the megasplay. The mudstones show different degrees of deformation spanning from occasional fractures to intensely fractured scaly claystones of up to >10 cm thickness. Sparse faulting with low displacement (usually <2cm) is seen with both normal and reverse sense of slip. Post-cruise rock deformation experiments will relate physical properties to the earthquake response monitored by the observatory array.

Oceanographic Mower Cruise

NASA Astrophysics Data System (ADS)

Valencia, J.; Ercilla, G.; Hernández-Molina, F. J.; Casas, D.

2015-04-01

The MOWER Cruise has executed a geophysics and geologic expedition in the Gulf of Cádiz (sector adjacent to the Strait of Gibraltar) and west off Portugal, in the framework of the coordinate research project MOWER "Erosive features and associated sandy deposits generated by the Mediterranean Outflow Water (MOW) around Iberia: paleoceanographic, sedimentary & economic implications" (CTM 2012-39599-C03). The main aim of this project is to identify and study the erosional features (terraces and channels) and associated sedimentary deposits (sandy contourites) generated by the Mediterranean Water Masses around the middle continental slope of Iberia (The Mediterranean Outflow Water - MOW - in the Atlantic margins), their Pliocene and Quaternary evolution and their paleoceanographic, sedimentary and economic implications. This objective directly involves the study of alongslope (contourite) processes associated with the MOW and across-slope (turbiditic flows, debris flows, etc.) processes in the sedimentary stacking pattern and evolution of the Iberian margins. The MOWER project and cruise are related to the Integrated Ocean Drilling Program (IODP) Expedition 339 (Mediterranean Outflow). It is also linked and coordinated with CONDRIBER Project "Contourite drifts and associated mass-transport deposits along the SW Iberia margin - implications to slope stability and tsunami hazard assessment" (2013-2015) funded by the Fundação para a Ciência e Tecnologia, Portugal (PTDC/GEO-GEO/4430/2012).

Stress magnitude and orientation in deep coalbed biosphere off Shimokita ~IODP Expedition337 drilling project

NASA Astrophysics Data System (ADS)

Wu, H. Y.; Lin, W.; Yamada, Y.

2015-12-01

One of IODP expedition (Borehole C0020A) is located in the forearc basin formed by the subducting between Pacific plate and Eurasian plate off Shimokita Peninsula. This ~2.5km deep scientific drilling collected the high-resolution wire-line resistivity logging, caliper data, Dipole Sonic waveforms; geophysical properties measurements and core samples. The riser drilling operations produced one good conditions borehole even this drilling operation was applied right after 311 Tohoku earthquake. Based on the high-resolutions Formation Micro Imager (FMI) images, both breakout and tensile fractures along the borehole wall indicating the in-situ stress orientation are detected in the unwrapped resistivity images. In this research, a reasonable geomechanical model based on the breakout width and physical properties is constructed to estimate the stress magnitude profile in this borehole. Besides, the openhole leak-off test revealed the information of Shmin magnitude. In general, stress direction along the borehole is slight rotated to east with drilling to the bottom of the borehole. Geomechanical model constarined the principal stresses in Strike-slip stress regime to satisfy the occurrences of borehole enlargements and tensile fractures. Some blank zones with no borehole wall failure and vertical fractures indicated the stress anomaly might be controlled by local lithological facies. Comparing to the JFAST drilling, this site is out of Japan trench slip zone and shows almost parallel stress direcion to the trench (~90 degree apart of Shmin with Site C0019).

Meso- and microscale vein structures in fore-arc basalts and boninites related to post-magmatic tectonic deformation in the outer Izu-Bonin-Mariana fore arc system: preliminary results from IODP Expedition 352

NASA Astrophysics Data System (ADS)

Quandt, Dennis; Micheuz, Peter; Kurz, Walter

2016-04-01

The International Ocean Discovery Program (IODP) Expedition 352 aimed to drill through the entire volcanic sequence of the Izu-Bonin-Mariana fore arc. Two drill sites are situated on the outer fore arc composed of fore arc basalts (FAB) whereas two more sites are located on the upper trench slope penetrating the younger boninites. First results from IODP Expedition 352 and preliminary post-cruise data suggest that FAB were generated by decompression melting during near-trench sea-floor spreading, and that fluids from the subducting slab were not involved in their genesis. Subduction zone fluids involved in boninite genesis appear to have been derived from progressively higher temperatures and pressures over time as the subducting slab thermally matured. Structures within the drill cores combined with borehole and site survey seismic data indicate that tectonic deformation in the outer Izu-Bonin-Mariana fore arc is mainly post-magmatic associated with the development of syn-tectonic sedimentary basins. Within the magmatic basement deformation was accommodated by shear along cataclastic fault zones and the formation of tension fractures, shear fractures and hybrid (tension and shear) fractures. Veins form by mineral filling of tension or hybrid fractures and show no or limited observable macroscale displacement along the fracture plane. (Low Mg-) Calcite and/or various types of zeolite are the major vein constituents, where the latter are considered to be alteration products of basaltic glass. Micrite contents vary significantly and are related to neptunian dikes. In boninites calcite develops mainly blocky shapes but veins with fibrous and stretched crystals also occur in places indicating antitaxial as well as ataxial growth, respectively. In FAB calcite forms consistently blocky crystals without any microscopic identifiable growth direction suggesting precipitation from a highly supersaturated fluid under dropping fluid pressure conditions. However, fluid pressure must have been high before calcite precipitation in order to fracture the host rock and to place host rock fragments within the vein. Cross-cutting relationships of veins and zonation consisting of blocky calcite and micritic calcite indicate multiple and probably chaotic fracturing and repeated mineral precipitation or emplacement of micrite, respectively. Hydrothermal fluids affected significantly the vein walls by forming selvages of asbestiform mineral bands and alteration halos along the vein-wall rock contact. Rock fragments show the same selvages as the vein walls. Moreover, volcanic glass can be completely altered to zeolite and/or palagonite. This hydrothermal activity took place shortly after magma cooling since vein frequency varies with depth but does not seem to correlate with the proximity to faults. With increasing depth, calcite grains in both sequences exhibit deformation microstructures more frequently than at shallower core intervals. These microstructures include thin twinning (type I twins), increasing in width with depth (type I and type II twins), slightly curved twins, and subgrain boundaries indicative of incipient plastic deformation. The differential stresses (≥ 50 MPa) that triggered vein deformation were presumably related to IBM forearc extension due to the retreating Pacific lower plate.

Structure and clay mineralogy: borehole images, log interpretation and sample analyses at Site C0002 Nankai Trough accretionary prism

NASA Astrophysics Data System (ADS)

Jurado, Maria Jose; Schleicher, Anja

2015-04-01

Our research focused on the characterization of fracture and fault structures from the deep Nankai Trough accretionary prism in Japan. Logging Data and cuttings samples from the two most recent International Ocean Discovery Program (IODP) Expeditions 338 and 348 of the NanTroSEIZE project were analyzed by Logging While Drilling (LWD) oriented images, geophysical logs and clay mineralogy. Both expeditions took place at Site C0002, but whereas Hole C0002F (Expedition 338) was drilled down to 2004.5 mbsf, Hole C0002N and C0002P (Expedition 348) reached a depth of 2325.5 mbsf and 3058.8 mbsf respectively. The structural interpretation of borehole imaging data illustrates the deformation within the fractured and faulted sections of the accretionary prism. All drill holes show distinct areas of intense fracturing and faulting within a very clay-dominated lithology. Here, smectite and illite are the most common clay minerals, but the properties and the role they may play in influencing the fractures, faults and folds in the accretionary prism is still not well understood. When comparing clay mineralogy and fracture/fault areas in hole C0002F (Expedition 338), a trend in the abundance of illite and smectite, and in particular the swelling behavior of smectite is recognizable. In general, the log data provided a good correlation with the actual mineralogy and the relative abundance of clay. Ongoing postcruise preliminary research on hole C0002 N and C0002P (Expedition 348) should confirm these results. The relationship between fracture and fault structures and the changes in clay mineralogy could be explained by the deformation of specific areas with different compaction features, fluid-rock interaction processes, but could also be related to beginning diagenetic processes related to depth. Our results show the integration of logging data and cutting sample analyses as a valuable tool for characterization of petrophysical and mineralogical changes of the structures of the Nankai accretionary prism. This is critical for our understanding of clay-fluid interaction and mechanical properties duing fault displacements and seismogenesis.

Palaeobathymetric Interpretations using Foraminiferal Data from the North-west Continental Shelf off Western Australia, IODP Expedition 356

NASA Astrophysics Data System (ADS)

Mamo, B. L.; Renema, W.; Auer, G.; Groeneveld, J.; Gallagher, S. J.; Fulthorpe, C.; Bogus, K.; Expedition 356 Scientists, I.

2016-12-01

In 2015, Integrated Ocean Discovery Program Expedition 356 drilled along the passive margin off the West Australian coast to investigate the history of the Indonesian Throughflow (ITF) and its integral role in the development of global thermohaline circulation and climate. Throughout the expedition, a suite of foraminiferal analyses were employed to assess stratigraphy and benthic environments. Planktic foraminifera were primarily used for biostratigraphy and an incredibly diverse benthic fauna ( 260 species) yielded information regarding palaeobathymetric settings and variable conditions at the sediment-water interface. Benthic foraminiferal biofacies are particularly sensitive to changes in environmental conditions and have rapid turnover making them ideal proxies for monitoring physical and chemical changes in marine environments. When these data are combined with a multi-proxy approach incorporating lithostratigraphic and other microfossil data, a robust understanding of past environments can be realised. Stretching from the Northern Carnarvon Basin north to the Roebuck Basin, several distinct biofacies were isolated at sites U1461-U1464 that reveal an array of marine settings and events that span from the Miocene through to the Pleistocene. These features include water depths ranging from Miocene shallows (including larger benthic foraminifera) to Pliocene bathyal depths ( 1000 m), the occurrence of key indicator species for both the Leeuwin Current and the West Pacific Warm Pool (Asterorotalia and Pseudorotalia), and episodes of downslope sediment transport. Here we present the main isolated biofacies, their associated lithofacies and their implications for reconstructing fluctuating sea-level, thermohaline circulation and sediment transport in a changing marine landscape.

Systematics of Alkali Metals in Pore Fluids from Serpentinite Mud Volcanoes: IODP Expedition 366

NASA Astrophysics Data System (ADS)

Wheat, C. G.; Ryan, J.; Menzies, C. D.; Price, R. E.; Sissmann, O.

2017-12-01

IODP Expedition 366 focused, in part, on the study of geo­chemical cycling, matrix alteration, material and fluid transport, and deep biosphere processes within the subduction channel in the Mariana forearc. This was accomplished through integrated sampling of summit and flank regions of three active serpentinite mud volcanoes (Yinazao (Blue Moon), Asùt Tesoro (Big Blue), and Fantangisña (Celestial) Seamounts). These edifices present a transect of depths to the Pacific Plate, allowing one to characterize thermal, pressure and compositional effects on processes that are associated with the formation of serpentinite mud volcanoes and continued activity below and within them. Previous coring on ODP Legs 125 and 195 at two other serpentinite mud volcanoes (Conical and South Chamorro Seamounts) and piston, gravity, and push cores from several other Mariana serpentinite mud volcanoes add to this transect of sites where deep-sourced material is discharged at the seafloor. Pore waters (149 samples) were squeezed from serpentinite materials to determine the composition of deep-sourced fluid and to assess the character, extent, and effect of diagenetic reactions and mixing with seawater on the flanks of the seamounts as the serpentinite matrix weathers. In addition two Water Sampler Temperature Tool (WSTP) fluid samples were collected within two of the cased boreholes, each with at least 30 m of screened casing that allows formations fluids to discharge into the borehole. Shipboard results for Na and K record marked seamount-to-seamount differences in upwelling summit fluids, and complex systematics in fluids obtained from flank sites. Here we report new shore-based Rb and Cs measurements, two elements that have been used to constrain the temperature of the deep-sourced fluid. Data are consistent with earlier coring and drilling expeditions, resulting in systematic changes with depth (and by inference temperature) to the subduction channel.

Historical methane hydrate project review

USGS Publications Warehouse

Collett, Timothy; Bahk, Jang-Jun; Frye, Matt; Goldberg, Dave; Husebo, Jarle; Koh, Carolyn; Malone, Mitch; Shipp, Craig; Torres, Marta

2013-01-01

In 1995, U.S. Geological Survey made the first systematic assessment of the volume of natural gas stored in the hydrate accumulations of the United States. That study, along with numerous other studies, has shown that the amount of gas stored as methane hydrates in the world greatly exceeds the volume of known conventional gas resources. However, gas hydrates represent both a scientific and technical challenge and much remains to be learned about their characteristics and occurrence in nature. Methane hydrate research in recent years has mostly focused on: (1) documenting the geologic parameters that control the occurrence and stability of gas hydrates in nature, (2) assessing the volume of natural gas stored within various gas hydrate accumulations, (3) analyzing the production response and characteristics of methane hydrates, (4) identifying and predicting natural and induced environmental and climate impacts of natural gas hydrates, and (5) analyzing the effects of methane hydrate on drilling safety.Methane hydrates are naturally occurring crystalline substances composed of water and gas, in which a solid water-­‐lattice holds gas molecules in a cage-­‐like structure. The gas and water becomes a solid under specific temperature and pressure conditions within the Earth, called the hydrate stability zone. Other factors that control the presence of methane hydrate in nature include the source of the gas included within the hydrates, the physical and chemical controls on the migration of gas with a sedimentary basin containing methane hydrates, the availability of the water also included in the hydrate structure, and the presence of a suitable host sediment or “reservoir”. The geologic controls on the occurrence of gas hydrates have become collectively known as the “methane hydrate petroleum system”, which has become the focus of numerous hydrate research programs.Recognizing the importance of methane hydrate research and the need for a coordinated effort, the U.S. Congress enacted Public Law 106-­‐193, the Methane Hydrate Research and Development Act of 2000. This Act called for the Secretary of Energy to begin a methane hydrate research and development program in consultation with other U.S. federal agencies. At the same time a new methane hydrate research program had been launched in Japan by the Ministry of International Trade and Industry to develop plans for a methane hydrate exploratory drilling project in the Nankai Trough. Since this early start we have seen other countries including India, China, Canada, and the Republic of Korea establish large gas hydrate research and development programs. These national led efforts have also included the investment in a long list of important scientific research drilling expeditions and production test studies that have provided a wealth of information on the occurrence of methane hydrate in nature. The most notable expeditions and projects have including the following:-­‐Ocean Drilling Program Leg 164 (1995)-­‐Japan Nankai Trough Project (1999-­‐2000)-­‐Ocean Drilling Program Leg 204 (2004)-­‐Japan Tokai-­‐oki to Kumano-­‐nada Project (2004)-­‐Gulf of Mexico JIP Leg I (2005)-­‐Integrated Ocean Drilling Program Expedition 311 (2005)-­‐Malaysia Gumusut-­‐Kakap Project (2006)-­‐India NGHP Expedition 01 (2006)-­‐China GMGS Expedition 01 (2007)-­‐Republic of Korea UBGH Expedition 01 (2007)-­‐Gulf of Mexico JIP Leg II (2009)-­‐Republic of Korea UBGH Expedition 02 (2010)-­‐MH-­‐21 Nankai Trough Pre-­‐Production Expedition (2012-­‐2013)-­‐Mallik Gas Hydrate Testing Projects (1998/2002/2007-­‐2008)-­‐Alaska Mount Elbert Stratigraphic Test Well (2007)-­‐Alaska Iġnik Sikumi Methane Hydrate Production Test Well (2011-­‐2012)Research coring and seismic programs carried out by the Ocean Drilling Program (ODP) and Integrated Ocean Drilling Program (IODP), starting with the ODP Leg 164 drilling of the Blake Ridge in the Atlantic Ocean in 1995, have also contributed greatly to our understanding of the geologic controls on the formation, occurrence, and stability of gas hydrates in marine environments. For the most part methane hydrate research expeditions carried out by the ODP and IODP provided the foundation for our scientific understanding of gas hydrates. The methane hydrate research efforts under ODP-­‐IODP have mostly dealt with the assessment of the geologic controls on the occurrence of gas hydrate, with a specific goal to study the role methane hydrates may play in the global carbon cycle.Over the last 10 years, national led methane hydrate research programs, along with industry interest have led to the development and execution of major methane hydrate production field test programs. Two of the most important production field testing programs have been conducted at the Mallik site in the Mackenzie River Delta of Canada and in the Eileen methane hydrate accumulation on the North Slope of Alaska. Most recently we have also seen the completion of the world’s first marine methane hydrate production test in the Nankai Trough in the offshore of Japan. Industry interest in gas hydrates has also included important projects that have dealt with the assessment of geologic hazards associated with the presence of hydrates.The scientific drilling and associated coring, logging, and borehole monitoring technologies developed in the long list of methane hydrate related field studies are one of the most important developments and contributions associated with methane hydrate research and development activities. Methane hydrate drilling has been conducted from advanced scientific drilling platforms like the JOIDES Resolution and the D/V Chikyu, which feature highly advanced integrated core laboratories and borehole logging capabilities. Hydrate research drilling has also included the use of a wide array of industry, geotechnical and multi-­‐service ships. All of which have been effectively used to collect invaluable geologic and engineering data on the occurrence of methane hydrates throughout the world. Technologies designed specifically for the collection and analysis of undisturbed methane hydrate samples have included the development of a host of pressure core systems and associated specialty laboratory apparatus. The study and use of both wireline conveyed and logging-­‐while-­‐drilling technologies have also contributed greatly to our understanding of the in-­‐situ nature of hydrate-­‐bearing sediments. Recent developments in borehole instrumentation specifically designed to monitor changes associated with hydrates in nature through time or to evaluate the response of hydrate accumulations to production have also contributed greatly to our understanding of the complex nature and evolution of methane hydrate systems.Our understanding of how methane hydrates occur and behave in nature is still growing and evolving – we do not yet know if methane hydrates can be economically produced, nor do we know fully the role of hydrates as an agent of climate change or as a geologic hazard. But it is known for certain that scientific drilling has contributed greatly to our understanding of hydrates in nature and will continue to be a critical source of the information to advance our understanding of methane hydrates.

Distribution of physical properties and timing of relative uplift in upper plate off Costa Rica: IODP Expedition 344

NASA Astrophysics Data System (ADS)

Saiki, A.; Hashimoto, Y.

2015-12-01

Evolution of physical properties in subduction zone is a key to understand lithification processes, location of decollement, and stress distribution. In this study, we examined the physical properties of sediments using on-board data and laboratory experimental data on sediments obtained off Costa Rica margin. Target sites are in the Integrate Ocean Drilling Program (IODP) Expedition 344 off Costa Rica, including reference sites (U1381 and U1414), mid-slope site (U1378, U1380) and upper-slope site (U1413). Seven samples from reference sites were analyzed. Laboratory experiments for velocity and porosity measurements were conducted with variation of effective pressure. Velocity-porosity relationships from on-board data and from laboratory experiments are comparable. The porosity-effective pressure curves under isotropic condition were converted to the curves under uniaxial condition (Teeuw, 1971). Using the normal consolidation curves under uniaxial stress conditions, we converted onboard porosity to effective pressure and fluid pressure. In reference sites, hydrostatic fluid pressure was estimated as expected as a reference sites, suggesting that porosity-effective pressure relationship was obtained correctly by experiments and it can be adapted to estimation of fluid pressure for the wedge sites. The porosity-effective pressure relationship under isotropic conditions were used for the estimation in wedge sites. In wedge sites, estimated pore pressures show lower than hydrostatic pressure, suggesting that onboard porosity was lower than that under normal compaction. The lower porosity can be caused by relative uplift from deeper portion. The amount of relative uplift can be estimated by differences in porosity-depth relationships between onboard data and experimental data. The amount of relative uplift for each site shows more than ~1000m up to ~5000m. The small error in porosity depth curve from experimental data makes relative uplift larger or smaller exponentially in the deeper portion. The increment of relative uplift, however, starts from about 1Ma in each site, suggesting some events were occurred at the timing. Laboratory experiments under differential stress should be conducted in the near future because smaller porosity is expected under differential stress conditions.

IODP/ICDP Expedition 364-Drilling the Cretaceous-Paleogene Chicxulub impact crater: Insights into large craters formation and their effect on life.

NASA Astrophysics Data System (ADS)

Gulick, S. P. S.; Morgan, J. V.; Fucugauchi, J. U.; Bralower, T. J.; Chenot, É.; Christeson, G. L.; Claeys, P.; Cockell, C. S.; Collins, G. S.; Coolen, M.; Gebhardt, C.; Goto, K.; Kring, D. A.; Xiao, L.; Lowery, C.; Mellett, C.; Ocampo-Torres, R.; Osinski, G. R.; Perez-Cruz, L. L.; Pickersgill, A.; Poelchau, M.; Rae, A.; Rasmussen, C.; Rebolledo-Vieyra, M.; Riller, U. P.; Sato, H.; Schmitt, D. R.; Smit, J.; Tikoo, S.; Tomioka, N.; Whalen, M. T.; Zylberman, W.; Jones, H.; Gareth, C.; Wittmann, A.; Lofi, J.; Yamaguchi, K. E.; Ferrière, L.

2016-12-01

An international project to drill the Chicxulub impact crater was conducted in April and May, 2016 as Expedition 364 of the International Ocean Discovery Program (IODP) and International Continental Scientific Drilling Project (ICDP). Site M0077 is located offshore Yucatan in the southern Gulf of Mexico. The target was to core the only pristine terrestrial peak ring and to measure physical properties of the entire borehole. Specific questions included: What rocks comprise a topographic peak ring? How are peak rings formed? How are rocks weakened during large impacts to allow them to collapse and form relatively wide, flat craters? What insights arise from biologic recovery in the Paleogene within a potentially "toxic" ocean basin? Are impact craters (including peak rings) habitats for life? Coring occurred from 503 - 1334.7 mbsf with nearly 100% recovery. Wireline logs were collected from ultra slimline tools to total depth including gamma ray, magnetic susceptibility, sonic, borehole fluid temperature and conductivity, resistivity data, borehole images, and a finely spaced vertical seismic profile. Stratigraphy cored included 110 m of Eocene and Paleocene carbonates, 130 m of allochthonous impactites, and 590 m of crustal basement with dikes. All cores were measured using a shipboard core logger (density, gamma ray, magnetic susceptibility and resistivity) and shorebased dual energy, 0.3 mm resolution CT scanner. These data allow us to: 1) refine numerical models of the formation of the Chicxulub impact structure; 2) place constraints on environmental perturbations that led to the K-Pg mass extinction; 3) improve simulations of impact craters on other planetary bodies; 4) examine deformation mechanisms for insights into how rocks weaken during impacts; 5) study impact generated hydrothermal systems and 6) understand the effects of impacts on the deep biosphere including as a habitat for microbial life with implications for evolution on Earth and astrobiology. Key results are that the Chicxulub peak ring is formed from fractured basement rocks that may host a subsurface biosphere. The impactite layer overlying the peak ring in turn provides insight into resurge and tsunami processes, while the Paleogene sediments contain the record of the recovery of life after the mass extinction event.

The use of amino acid indices for assessing organic matter quality and microbial abundance in deep-sea Antarctic sediments of IODP Expedition 318

USGS Publications Warehouse

Carr, Stephanie A; Mills, Christopher T.; Mandernack, Kevin W

2016-01-01

The Adélie Basin, located offshore of the Wilkes Land margin, experiences unusually high sedimentation rates (~ 2 cm yr− 1) for the Antarctic coast. This study sought to compare depthwise changes in organic matter (OM) quantity and quality with changes in microbial biomass with depth at this high-deposition site and an offshore continental margin site. Sediments from both sites were collected during the International Ocean Drilling (IODP) Program Expedition 318. Viable microbial biomass was estimated from concentrations of bacterial-derived phospholipid fatty acids, while OM quality was assessed using four different amino acid degradation proxies. Concentrations of total hydrolysable amino acids (THAA) measured from the continental margin suggest an oligotrophic environment, with THAA concentrations representing only 2% of total organic carbon with relative proportions of non-protein amino acids β-alanine and γ-aminobutyric acid as high as 40%. In contrast, THAA concentrations from the near-shore Adélie Basin represent 40%–60% of total organic carbon. Concentrations of β-alanine and γ-aminobutyric acid were often below the detection limit and suggest that the OM of the basin as labile. DI values in surface sediments at the Adélie and margin sites were measured to be + 0.78 and − 0.76, reflecting labile and more recalcitrant OM, respectively. Greater DI values in deeper and more anoxic portions of both cores correlated positively with increased relative concentrations of phenylalanine plus tyrosine and may represent a change of redox conditions, rather than OM quality. This suggests that DI values calculated along chemical profiles should be interpreted with caution. THAA concentrations, the percentage of organic carbon (CAA%) and total nitrogen (NAA%) represented by amino acids at both sites demonstrated a significant positive correlation with bacterial abundance estimates. These data suggest that the selective degradation of amino acids, as indicated by THAA concentrations, CAA% or NAA% values may be a better proxy for describing the general changes in sedimentary bacterial abundances than total organic matter or bulk sedimentation rates.

An Early Middle Eocene Orbital Scale Benthic Isotope Record From IODP Site 1408, Newfoundland Rise

NASA Astrophysics Data System (ADS)

Wu, F.; Lawler, N.; Penman, D. E.; Zachos, J. C.; Kirtland Turner, S.; Norris, R. D.; Wilson, P. A.; Hull, P. M.

2014-12-01

The long-term Paleogene global cooling trend and eventual glaciation of Antarctica has been attributed to a reduction in greenhouse gas levels as well as changes in the configuration of high-latitude oceanic gateways. This major trend in climate and forcing is known to have initiated in the early middle Eocene, between 44-49 Mya, yet our understanding of the detailed evolution of climate and oceanic circulation and carbon chemistry of this critical interval has been limited for lack of high-resolution proxy climate records. Integrated Ocean Drilling Program (IODP) Expedition 342, designed in part to address this deficiency, successfully recovered highly expanded sequences of middle Eocene sediment from multiple sites in the western North Atlantic, with several sites characterized by high sedimentation rates (>2.8 cm/kyr) and pronounced lithologic cycles. Using samples from cores recovered at one of these sites, 1408, located on Southeast Newfoundland Ridge, we are reconstructing the first orbital-scale deep sea δ18O and δ13C records spanning a ~1.6 million year interval (~Chron 20r) of the middle Eocene. Based on analyses of benthic foraminifer N. truempyi, our preliminary data reveal distinct high-frequency cycles with periods matching those of the orbital cycles, particularly precession and obliquity. Cross spectral analysis of δ18O, δ13C and lithologic records reveal a high degree of coherency, implying a high sensitivity in local sediment fluxes and bottom water chemistry (and circulation) to orbital forcing. Also, given the location and depth (~2600 m at 50 Ma), Site 1408 constrains the end-member composition of northern component bathyal bottom waters so that comparison with benthic isotope records from the south Atlantic and other basins can be used to assess ocean circulation patterns in the mid-Eocene. In general, bottom water temperatures appear to have been warmer, and DIC δ13C lower than observed elsewhere. Thus, our preliminary results are consistent with the absence of significant bottom water production in the North Atlantic at this time. This record will eventually be part of a longer Eocene record being assembled by a consortium of Expedition 342 Scientists.

IODP expedition 347: Baltic Sea basin paleoenvironment and biosphere

NASA Astrophysics Data System (ADS)

Andrén, T.; Barker Jørgensen, B.; Cotterill, C.; Green, S.; IODP expedition 347 scientific party, the

2015-12-01

The Integrated Ocean Drilling Program (IODP) expedition 347 cored sediments from different settings of the Baltic Sea covering the last glacial-interglacial cycle. The main aim was to study the geological development of the Baltic Sea in relation to the extreme climate variability of the region with changing ice cover and major shifts in temperature, salinity, and biological communities. Using the Greatship Manisha as a European Consortium for Ocean Research Drilling (ECORD) mission-specific platform, we recovered 1.6 km of core from nine sites of which four were additionally cored for microbiology. The sites covered the gateway to the North Sea and Atlantic Ocean, several sub-basins in the southern Baltic Sea, a deep basin in the central Baltic Sea, and a river estuary in the north. The waxing and waning of the Scandinavian ice sheet has profoundly affected the Baltic Sea sediments. During the Weichselian, progressing glaciers reshaped the submarine landscape and displaced sedimentary deposits from earlier Quaternary time. As the glaciers retreated they left a complex pattern of till, sand, and lacustrine clay, which in the basins has since been covered by a thick deposit of Holocene, organic-rich clay. Due to the stratified water column of the brackish Baltic Sea and the recurrent and widespread anoxia, the deeper basins harbor laminated sediments that provide a unique opportunity for high-resolution chronological studies. The Baltic Sea is a eutrophic intra-continental sea that is strongly impacted by terrestrial runoff and nutrient fluxes. The Holocene deposits are recorded today to be up to 50 m deep and geochemically affected by diagenetic alterations driven by organic matter degradation. Many of the cored sequences were highly supersaturated with respect to methane, which caused strong degassing upon core recovery. The depth distributions of conservative sea water ions still reflected the transition at the end of the last glaciation from fresh-water clays to Holocene brackish mud. High-resolution sampling and analyses of interstitial water chemistry revealed the intensive mineralization and zonation of the predominant biogeochemical processes. Quantification of microbial cells in the sediments yielded some of the highest cell densities yet recorded by scientific drilling.

Occurrence of microbial acetate-oxidation in ~2 km-deep coal-bearing sediments off the Shimokita Peninsula, Japan (IODP Expedition 337)

NASA Astrophysics Data System (ADS)

Ijiri, A.; Inagaki, F.

2015-12-01

During the Integrated Ocean Drilling Program (IODP) Expedition 337 in 2012, the riser-drilling vessel Chikyu extended the previous world depth record of scientific ocean drilling and made one of the deepest scientific borehole down to 2466 m below the seafloor (mbsf) at Site C0020 Hole A off the Shimokita Peninsula, Japan. The sedimentary sequence consists of 17 lignite layers below 1.5 km bellow the seafloor. Microbiological and geochemical data consistently showed evidence for the existence of microbial communities associated with lignite coal beds in the coal-bearing sediments (Inagaki and Hinrichs et al., Science, 2015). Since lignite coals produce substantial dissolved organic compounds during the burial alternation process, volatile fatty acids may play important roles for microbial life and its activity in the deep sedimentary environment. To address this hypothesis, we measured methanogenic and acetate-oxidation activities by radiotracer incubation experiments using 14C-labelled substrate ([2-14C]-acetate) immediately after core recovery. Activity of aceticlastic methanogenesis was observed in the sediment above the coal-baring layers (>1990 mbsf), ranging from 0.2 to 1.2 pmol cm-3 d-1. The highest activity was observed in a coal-bed horizon at 1990 mbsf. However, aceticlastic methanogenesis was below the detection limit in sediment samples below the 2 km-coal layers. Activity of acetate oxidation to CO2 was measured by 14CO2 production rate from [2-14C]-acetate. Interestingly, the acetate-oxidation activity was observed in sediments above the coal beds, which values were generally higher than those of methanogenesis with the maximum value of 33 pmol cm-3 d-1 at 1800 mbsf. The rates gradually decreased with increasing depth from 1800 mbsf and reached below the detection limit (i.e., 0.05 pmol cm-3 d-1) in 2 km-deep coal-bed samples. The occurrence of relatively high acetate oxidation at ~1800 mbsf above the coal formation suggests that microbes respire acetate with available electron acceptors such as glauconitic iron oxides in the deep sedimentary environment.

Thermal evolution of Site U1414 by stable isotopes δ13C and δ18O, 87Sr/86Sr and fluid inclusion analyses, IODP Expedition 344

NASA Astrophysics Data System (ADS)

Brandstätter, Jennifer; Kurz, Walter; Krenn, Kurt; Richoz, Sylvain

2017-04-01

IODP Expedition 344 is the second expedition in course of the Costa Rica Seismogenesis Project (Program A), that was designed to reveal processes that effect nucleation and seismic rupture of large earthquakes at erosional subduction zones. Site 344-U1414, located 1 km seaward of the deformation front offshore Costa Rica, serves to evaluate fluid-rock interaction and geochemical processes linked with the tectonic evolution of the incoming Cocos Plate from the Early Miocene up to recent times. Combined isotope analyses and microthermometric analyses of fluid inclusions of hydrothermal veins within lithified sediments and the igneous basement (Cocos Ridge basalt), was used to reveal the thermal history of Site 344-U1414. Veins in the sedimentary rocks are mainly filled by coarse-grained calcite and subordinately by quartz. Veins within the basalt show polymineralic filling of clay minerals, calcite, aragonite and quartz. Blocky veins with embedded wall rock fragments, appearing in the sediments and in the basalt, indicate hydraulic fracturing. The carbon isotopic composition of the vein calcite suggest the influence of a CO2 -rich fluid mixed with seawater (-3.0 to -0.4‰ V-PDB) and the δ18O values can be differentiated in two groups, depending on the formation temperature (-13.6 to -9.3‰ and -10.8 to -4.7‰ V-PDB). 87Sr/86Sr ratios from the veins confirm the results of the stable isotope analyses, with a higher 87Sr/86Sr ratio close to seawater composition and lower ratios indicating the influence of basalt alteration. The hydrothermal veins contain different types of fluid inclusions with high and low entrapment temperatures and low saline fluids. The occurrence of decrepitated fluid inclusions, formed by increased internal overpressure, is related to isobaric heating. Elongated fluid inclusion planes, arc-like fluid inclusions and low homogenization temperatures suggest subsequent isobaric cooling. The stable isotopic content, strontium isotopic composition and the results of fluid inclusion analyses indicate that the source of fluids is a mixture of mobilized pore water and invaded seawater that communicated with high temperature CO2-rich fluids. We propose that lithification of the sediments was accompanied with a first stage of vein development in the Middle Miocene and was a result of the Galapagos hotspot activity. Heat advection led to subsequent vein modification related to isobaric heating. The latest mineralization occurred during crustal cooling up to recent times.

Oxidation State of Iron in the Izu-Bonin Arc Initial Magma and Its Influence Factors

NASA Astrophysics Data System (ADS)

Li, H.; Arculus, R. J.; Brandl, P. A.; Hamada, M.; Savov, I. P.; Zhu, S.; Hickey-Vargas, R.; Tepley, F. J., III; Meffre, S.; Yogodzinski, G. M.; McCarthy, A.; Barth, A. P.; Kanayama, K.; Kusano, Y.; Sun, W.

2014-12-01

The redox state of mantle-derived magmas is a controversial issue, especially whether island arc basalts are more oxidized than those from mid-ocean ridges. Usually, arc magmas have higher Fe3+/Fe2+ and calculated oxygen fugacity (fO2) than mid-ocean ridge basalts (MORB). It is the high fO2 of arc magma that apparently delays onset of sulfide fractionation and sequestration of precious/base metals thereby facilitating the formation of many giant gold-copper deposits typically associated with subduction zones. But due to a paucity of Fe3+/Fe2+ data for primary mantle-derived arc magmas, the cause for high fO2 of these magma types is still controversial; causes may include inter alia subduction-released oxidized material addition to the mantle wedge source of arc magma, partial melting of subducted slab, and redox changes occurring during ascent of the magma. Fortunately, IODP expedition 351 drilling at IODP Site U1438 in the Amami-Sankaku Basin of the northwestern Philipine Sea, adjacent to the proto-Izu-Bonin Arc at the Kyushu-Palau Ridge (KPR), recovered not only volcaniclastics derived from the inception of Izu-Bonin Mariana (IBM) arc in the Eocene, but also similar materials for the Arc's subsequent evolution through to the Late Oligocene and abandonment of the KPR as a remnant arc. Samples of the pre-Arc oceanic crustal basement were also recovered enabling us to determine the fO2of the mantle preceding arc inception. As the oxidation state of iron in basaltic glass directly relates to the fO2 , the Fe3+/∑Fe ratio [Fe3+/(Fe3++ Fe2+)] of basaltic glass are quantified by synchrotron-facilitated micro X-ray Absorption Near Edge Structure (XANES) spectroscopy to reflect its fO2. Fe K-edge µ-XANES spectra were recorded in fluorescence mode at Beamline 15U1, Shanghai Synchrotron Radiation Facility (SSRF). Synthetic silicate glass with known Fe3+/∑Fe ratio was used in data handling. The experimental results as well as preliminary data from IODP Expedition 351 will be presented

Reconstructing the Glacial Cycle of the Last 150 ka in the Southern Bay of Bengal

NASA Astrophysics Data System (ADS)

Holmes, B.; Dekens, P.; Weber, M. E.; Lantzsch, H.; Reilly, B. T.; Das, S. K.; Martos, Y. M.; Williams, T.

2017-12-01

The Himalayas and resulting monsoonal climate provide the source and mechanism for sediment deposition in the Bay of Bengal. Sediments from the distal Bengal Fan collected during IODP expedition 354, with the exception the westernmost Site U1454, show a several meter thick, hemipelagic top layer representing the Late Quaternary. This interval has abundant foraminifera throughout and therefore presents a unique opportunity to reconstruct oceanographic conditions, alongside records of terrestrial climate variability. We reconstructed oceanographic conditions at IODP site U1452 (8°N, 87°E, 3671 m water depth), in the southern Bay of Bengal. The age model was constructed by tuning the core's sediment lightness, L*, to the EDML ice core. The Toba Ash 1 (73.7 ka) is an additional constraint leading to an age model with a total of 35 tie points. We sampled the top 3.5 m of sediment at 2 cm resolution, and picked between 8 to 30 tests of the mixed surface layer planktonic foraminifera G. sacculifer from each sample. The tests were cracked open between two glass plates and the sample was homogenized before being split into separate aliquots for d18O and Mg/Ca analysis. Mg/Ca data range from 2.5 to 4.1 mmol/mol and show a SST change of 2-4°C between glacial and interglacial times. The δ18O data range from -2.63 to 0.17‰. The data shows the shift from the cooler glacial period into the warming interglacial period at 15 ka ending the LGM. The apparent late timing of the deglaciation in the record could be an artifact of lower resolution of the δ18O data (compared to the benthic stack). It is also possible the offset in the timing is due to the age model limitations and the assumption of linear sedimentation rates between tie points. We will further explore the age model implications by measuring d18O on benthic foraminifera where available in the sediment core. In collaboration with scientists from IODP Expedition 354, this data can be used to examine the link between tropical ocean conditions, monsoon strength, and glacial cycles.

Three-dimensional Seismic Survey of the Continental-Ocean Transition Zone of the Northern South China Sea

NASA Astrophysics Data System (ADS)

Zhao, M.; Wang, Q.; Sibuet, J. C.; Sun, L.; Sun, Z.; Qiu, X.

2017-12-01

The South China Sea (SCS) is one of the largest marginal seas in the western Pacific, which has experienced extension, rifting, breakup, post-spreading magmatism on its northern margin during the Cenozoic era. The complexity of this margin is exacerbated by rifting and seafloor spreading processes, which developed at the expenses of the subducting proto-South China Sea. Based on Sun et al. (2014, 2016) proposals, 6 sites were drilled on the northern SCS margin from February to June 2017, during IODP Expeditions 367/368. The preliminary results indicate that the width of the COT is about 20 km and is different from the typical magma-poor Iberia margin whose width is around 100 km. The combination of three-dimensional (3D) Ocean Bottom Seismometers (OBS) refractive survey with IODP drilling results, will improve the drilling achievement and greatly contribute to the understanding of the specific mechanism of rifting and breakup processes of the northern SCS. In particular, it is expected to constrain: 1) the nature of the crust in the COT, 2) the degree of serpentinization of the upper mantle beneath the COT, and 3) the 3D extension of the COT, the oceanic crust and the serpentinized mantle. We firstly carry out the resolution tests and calculate the interval of OBSs using a ray tracing and travel time modelling software. 7-km interval between OBSs is the optimal interval for the resolution tests and ray coverage, which will provide optimal constraints for the characterization of the 20-km wide COT. The 3D seismic survey will be carried out in 2018. The design of the OBSs arrangement and the location of shooting lines are extremely important. At present, we propose 5 main profiles and 14 shooting lines along the multi-channel seismic lines already acquired in the vicinity of the 6 drilling sites. Any comments and suggestions concerning the OBSs arrangement will be appreciated. This work is supported by the Chinese National Natural Science Foundation (contracts 91428204, 41576070 and 41176053). Key words: Continental-ocean transition zone (COT); 3D refraction survey; IODP Expeditions 367/368; nature of crust.

Mutualistic Symbiosis between Researchers and Educators: the Case of Two Education Officers on the Joides Resolution

NASA Astrophysics Data System (ADS)

Cicconi, Alessia; Burgio, Marion; Cooper, Sharon

2017-04-01

Geoscience education from the primary school through the high school level is highly effected by the way teachers themselves deal with the teaching of science. Many studies on science education in general have found that teachers who lack research experience are less confident in teaching science with an inquiry methodology - the way that reflects how science really works and is found the most effective regarding students' achievement in science and their confidence in addressing STEM careers. The International Ocean Discovery Program (IODP) has carried out for years an education and outreach program that involves educators and teachers, with the position of Education Officer, in the expeditions on board the JOIDES Resolution (JR), an oceanographic vessel specialized in drilling ocean sediment cores for research purposes. This immersive experience gives teachers the opportunity to be part of the research process with the aim, among many others, to fill the gap that sometimes exists between how science is explained in textbooks and the real practice of scientific research. Using a scientific parallel, having teachers working with researchers could be considered a mutualistic symbiosis: on one hand researchers have a job, usually difficult to understand for the public and made simple by the teacher; on the other hand the teacher, working with researchers as a researcher will gain more confidence using an inquiry methodology in teaching science. In this oral presentation we want to present the outcomes of the outreach projects of two Education Officers, the first one who participated in Expedition 360 and the second one that will take part in the Expedition 367, in terms of 1) their perception and opinion of this immersive experience seen as professional development; 2) perceptions and opinions of teachers involved from shore, with or without their classes. This exploratory study has carried out with qualitative and quantitative methodology using questionnaires and surveys.

Ocean Drilling Science Plan to be released soon

NASA Astrophysics Data System (ADS)

Showstack, Randy

2011-04-01

The upcoming International Ocean Discovery Program, which is slated to operate from 2013 to 2023 and calls for an internationally funded program focused around four science themes, will pick up right where its predecessor, the Integrated Ocean Drilling Program, ends, explained Kiyoshi Suyehiro, president and chief executive officer of IODP, a convenient acronym that covers both programs. At a 5 April briefing at the 2011 European Geosciences Union General Assembly in Vienna, Austria, he outlined four general themes the new program will address. IODP involves 24 nations and utilizes different ocean drilling platforms that complement each other in drilling in different environments in the oceans.

IODP Expedition 351 Lithostratigraphy: Volcaniclastic Record of Izu-Bonin-Mariana (IBM) Arc Initiation

NASA Astrophysics Data System (ADS)

Barth, A. P.; Brandl, P. A.; Li, H.; Hickey-Vargas, R.; Jiang, F.; Kanayama, K.; Kusano, Y.; Marsaglia, K. M.; McCarthy, A.; Meffre, S.; Savov, I. P.; Tepley, F. J., III; Yogodzinski, G. M.

2014-12-01

The destruction of lithospheric plates by subduction is a fundamentally important process leading to arc magmatism and the creation of continental crust, yet subduction initiation and early magmatic arc evolution remain poorly understood. For many arc systems, onset of arc volcanism and early evolution are obscured by metamorphism or the record is deeply buried; however, initial products of arc systems may be preserved in forearc and backarc sedimentary records. IODP Expedition 351 recovered this history from the dispersed ash and pyroclast record in the proximal rear-arc of the northern IBM system west of the Kyushu-Palau Ridge. Drilling at Site U1438 in the Amami Sankaku Basin recovered a thick volcaniclastic record of subduction initiation and the early evolution of the Izu-Bonin Arc. A 160-m thick section of Neogene sediment overlies 1.3 kilometers of Paleogene volcaniclastic rocks with andesitic average composition; this volcaniclastic section was deposited on mafic volcanic basement rocks. The thin upper sediment layer is primarily terrigenous, biogenic and volcaniclastic mud and ooze with interspersed ash layers. The underlying Eocene to Oligocene volcaniclastic rocks are 33% tuffaceous mudstone, 61% tuffaceous sandstone, and 6% conglomerate with volcanic and rare sedimentary clasts commonly up to pebble and rarely to cobble size. The clastic section is characterized by repetitive conglomerate and sandstone-dominated intervals with intervening mudstone-dominated intervals, reflecting waxing and waning of coarse arc-derived sediment inputs through time. Volcanic lithic clasts in sandstones and conglomerates range from basalt to rhyolite in composition and include well-preserved pumice, reflecting a lithologically diverse and compositionally variable arc volcanic source.

Tephrostratigraphy and Provenance From IODP Expedition 352, Izu-Bonin Arc: Tracing Tephra Sources and Volumes From the Oligocene to Recent

NASA Astrophysics Data System (ADS)

Kutterolf, S.; Schindlbeck, J. C.; Robertson, A. H. F.; Avery, A.; Baxter, A. T.; Petronotis, K.; Wang, K.-L.

2018-01-01

Provenance studies of widely distributed tephras, integrated within a well-defined temporal framework, are important to deduce systematic changes in the source, scale, distribution, and changes in regional explosive volcanism. Here, we establish a robust tephrochronostratigraphy for a total of 157 marine tephra layers collected during IODP Expedition 352. We infer at least three major phases of highly explosive volcanism during Oligocene to Pleistocene time. Provenance analysis based on glass composition assigns 56 of the tephras to a Japan source, including correlations with 12 major and widespread tephra layers resulting from individual eruptions in Kyushu, Central Japan, and North Japan between 115 ka and 3.5 Ma. The remaining 101 tephras are assigned to four source regions along the Izu-Bonin arc. One, exclusively assigned to the Oligocene age, is proximal to the Bonin Ridge islands; two reflect eruptions within the volcanic front and back-arc of the central Izu-Bonin arc, and a fourth region corresponds to the Northern Izu-Bonin arc source. First-order volume estimates imply eruptive magnitudes ranging from 6.3 to 7.6 for Japan-related eruptions and between 5.5 and 6.5 for IBM eruptions. Our results suggest tephras between 30 and 22 Ma reflect a subtly different Izu-Bonin chemical signature compared to the recent arc. After a ˜9 Ma gap in eruption, tephra supply from the Izu-Bonin arc predominated from 15 to 5 Ma, and finally a subequal mixture of tephra sources from the (palaeo)Honshu and Izu-Bonin arcs occured within the last ˜5 Ma.

A 3 Kilometer Deep Window on the Interior of the Modern Nankai Accretionary Wedge: First Results from IODP Expedition 348

NASA Astrophysics Data System (ADS)

Tobin, Harold; Hirose, Takehiro; Demian, Saffer

2014-05-01

IODP Site C0002 at the Nankai Trough is now the deepest hole ever drilled in scientific ocean drilling, at 3058 meters below sea floor so far, and the first hole anywhere to access the deep interior of an active convergent margin. Site C0002 is part of the NanTroSEIZE transect off the Kii-Kumano region of Japan, imaged with 3D seismic reflection and drilled on a series of Chikyu expeditions to shed light on the processes around the up-dip edge of seismogenic locking and slip. At Site C0002, riser drilling has passed through the approximately 900 m thick Kumano forearc basin and pierced the underlying Miocene age accretionary wedge. Limited coring, extensive LWD logging, and continuous observations on drill cuttings reveal the materials and processes in the deep interior of the inner wedge. Predominantly fine-grained mudstones with common turbiditic sands were encountered, complexly deformed and exhibiting well-developed scaly clay fabrics, variable bedding dip with very steep dips prevailing, and veins that become more abundant with depth. The biostratigraphic age of the sediments in the lowermost part of the hole is thought to be ~ 9 - 11 Ma, with an assumed age of accretion of 3-5 Ma. Physical properties suggest that the inner wedge from 1600 - 3000 mbsf has quite homogeneous properties. Evidence from borehole logging, drilling parameters, and samples for the state of stress and pore pressure in this never-before accessed tectonic environment will be presented.

Lower plate deformation structures along the Costa Rica erosive plate boundary - results from IODP Expedition 344 (CRISP 2)

NASA Astrophysics Data System (ADS)

Brandstätter, Jennifer; Kurz, Walter; Micheuz, Peter; Krenn, Kurt

2015-04-01

The primary objective of Integrated Ocean Drilling Program (IODP) Expedition 344 offshore the Osa Peninsula in Costa Rica was to sample and quantify the material entering the seismogenic zone of the Costa Rican erosive subduction margin. Fundamental to this objective is an understanding of the nature of both the subducting Cocos plate crust and of the overriding Caribbean plate. The subducting Cocos plate is investigated trying to define its hydrologic system and thermal state. The forearc structures recorded by the sediment deposited on the forearc, instead, document periods of uplift and subsidence and provide important information about the process of tectonic erosion that characterizes the Costa Rica margin. Offshore the western margin of Costa Rica, the oceanic Cocos plate subducts under the Caribbean plate, forming the southern end of the Middle America Trench. Subduction parameters including the age, convergence rate, azimuth, obliquity, morphology, and slab dip all vary along strike. The age of the Cocos plate at the Middle America Trench decreases from 24 Ma offshore the Nicoya Peninsula to 15 Ma offshore the Osa Peninsula. Subduction rates vary from 70 mm/y offshore Guatemala to 90 mm/y offshore southern Costa Rica. Convergence obliquity across the trench varies from offshore Nicaragua, where it is as much as 25° oblique, to nearly orthogonal southeast of the Nicoya Peninsula. Passage of the Cocos plate over the Galapagos hotspot created the aseismic Cocos Ridge, an overthickened welt of oceanic crust. This ridge is ~25 km thick, greater than three times normal oceanic crustal thickness. During IODP Expedition 344, the incoming Cocos plate was drilled at sites U1381 and U1414. Site U1381 is located ~4.5 km seaward of the deformation front offshore the Osa Peninsula and Caño Island. It is located on a local basement high. Basement relief often focuses fluid flow, so data from this site are likely to document the vigor of fluid flow in this area. Site U1414 is located ~1 km seaward of the deformation front offshore the Osa Peninsula and Caño Island. Primary science goals at Site U1414 included characterization of the alteration state of the magmatic basement. Brittle structures within the incoming plate (sites U1380, U1414) are mineralized extensional fractures and shear fractures. The shear fractures mainly show a normal component of shear. Within the sedimentary sequence both types of fractures dip steeply (vertical to subvertical) and strike NNE-SSW. Deformation bands trend roughly ENE-WSW, sub-parallel to the trend of the Cocos ridge. Structures in the Cocos Ridge basalt mainly comprise mineralized veins at various orientations. A preferred orientation of strike directions was not observed. Some veins show straight boundaries, others are characterized by an irregular geometry characterized by brecciated wall rock clasts embedded within vein precipitates. The vein mineralization was analysed in detail by RAMAN spectroscopy. Precipitation conditions and fluid chemistry were analysed by fluid inclusions entrapped within vein minerals. Vein mineralizations mainly consist of carbonate (fibrous aragonite, calcite), chalcedony, and quartz. Vein mineralization is mainly characterized by zoned antitaxial growth of carbonate fibres including a suture along the central vein domains. Quartz is often characterized by fibre growth of crystals perpendicular to the vein boundaries, too. These zoned veins additinally have wall rock alteration seams consisting of clay minerals. The precipitation sequence basically indicates that fluid chemistry evolved from an CO2-rich towards a SiO2- rich fluid.

Reconstructing Sea Surface Conditions in the Bay of Bengal during the Mid-Pleistocene Transition

NASA Astrophysics Data System (ADS)

Lagos, A. D.; Dekens, P.; Reilly, B. T.; Selkin, P. A.; Meynadier, L.; Savian, J. F.

2017-12-01

During the Mid-Pleistocene Transition (MPT, 0.8-1.2Ma) Earth's glacial cycles transitioned from responding primarily to 41kyr obliquity cycles to responding to 100kyr eccentricity cycles. In the tropics, sea surface temperature (SST) in the eastern tropical Pacific cooled through the MPT, suggesting a strengthening of the equatorial Pacific zonal temperature gradient (Medina-Elizalde & Lea, 2005). The strong SST gradient would have intensified Walker Cell convection during the MPT and built up latent heat in the western Pacific, which could cause cold SST anomalies in the northern Indian Ocean (Liu et al., 2015). Due to a scarcity of records, it is unclear how climate and oceanic conditions evolved in the Indian Ocean during the MPT. A set of recent IODP expeditions, including 353 and 354, cored sediment from the Bay of Bengal. Several sites recovered by expedition 353 will be ideal for reconstructing monsoon intensity through time, while the expedition 354 cores from a longitudinal transect at 8°N are in a region not directly impacted by changes in freshwater input due to direct precipitation or run off. The sites are influenced by the northeastern migration of equatorial Indian Ocean water via the Southwest Monsoon Current, which supplies significant moisture to the monsoon. Expedition 354's southern Bay of Bengal sites are well situated for better understanding the link between the tropical Indian Ocean and the northern Bay of Bengal. We reconstructed sea surface conditions at IODP site 1452 (8°N, 87°E, 3670m water depth) in the distal Bengal Fan. A 3 meter long section of the core has been identified as the MPT using the Bruhnes/Matuyama, Jaramillo, and Cobb Mountain paleomagnetic reversals (France-Lanord et al., 2016). This section of site 1452 was sampled every 2cm ( 2kyr resolution). Approximately 30 G. sacculifer, a surface dwelling planktonic foraminifera, were picked from the 355-425μm size fraction. We measured Mg/Ca and δ18O on splits of the same material to reconstruct SST and δ18OSW. While this study will not reconstruct monsoon intensity, establishing the sea surface conditions for the southern Bay of Bengal will improve our understanding of the connection between the Indian Ocean and the monsoons through the MPT.

HLY0602: An integrated geophysical and geological study of the western Canada Basin

NASA Astrophysics Data System (ADS)

Lawver, L.; Davis, M.; van Avendonk, H.; Hornbach, M.; Vermeesch, P.; Henkart, M.; Henkart, P.

2006-12-01

The USCGC Healy cruise, HLY0602, departed Barrow on 19 July 2006 and ended prematurely on the 22nd of August in Nome, Alaska. HLY0602 was an integrated geophysical and geological study of the western Canada Basin including Northwind Ridge, Chukchi Cap and the Mendeleev Ridge. The IBCAO chart of Arctic bathymetry (Jakobsson, et al., 2000) gives the impression that there is comprehensive bathymetric coverage of the western Canada Basin. While in general, the IBCAO coverage is accurate, there are a number of places where multibeam data indicate significant discrepancies. For instance, the large north-south trough on the eastern margin of Chukchi Cap at 163°W appears on the IBCAO map to have a possible seamount on the eastern edge of the trough at 77.9°N. We surveyed that region and found an extremely flat-floored trough with a depth of 2708 ± 5 m with no sign of a seamount within 10 km of where it is shown on the IBCAO map. On Chukchi Cap there is an apparent ~ 900 m deep trough in the center that is in fact no deeper than ~ 700 m. Multibeam bathymetric surveying of Mendeleev Ridge confirmed the numerous pockmarks found by HLY0504 with even greater concentrations of the pockmarks found to the south along Mendeleev Ridge. A number of major slump features were found on the northern margin of Arlis Plateau at the southern end of Mendeleev Ridge. If the pockmarks are associated with high gas content, then the level of organic rich sediments may be similar to those found on the Lomonosov Ridge by IODP drilling (Backman et al., 2006). Backman, J., Moran, K., McInroy, D.B., Mayer, L.A., and the Expedition 302 Scientists, 2006. Proc. IODP, 302: Edinburgh (Integrated Ocean Drilling Program Management International, Inc.). doi:10.2204/iodp.proc.302.2006 Jakobsson, M., Cherkis, N.Z., Woodward, J., Coakley, B., Macnab, R., 2000. A new grid of Arctic bathymetry: a significant resorce for scientists and mapmakers. EOS Transactions 81(9), 89, 93, 96.

Using giant piston coring within IODP to track past earthquakes in the sedimentary record along the Japan Trench

NASA Astrophysics Data System (ADS)

Strasser, Michael

2017-04-01

"Submarine paleoseismology" is a promising approach to investigate deposits from the deep sea, where earthquakes leave traces preserved in stratigraphic succession. The concept of studying sedimentary event deposits for reconstructing past earthquake history and related impacts to the marine environment is increasingly being applied in various settings. However, at present we lack comprehensive data sets that allow conclusive distinctions between quality and completeness of the paleoseismic archives, as they may relate to different sediment transport, erosion and deposition processes vs. variability of intrinsic seismogenic behavior across different segments. Nevertheless, many recent studies, which are mostly based on conventional 10-m-long cores, demonstrate the potential of the research concept. With ECORD opening their mission specific platform approach to include giant piston coring within IODP, a new horizon has opened up for multi-coring expeditions fully dedicated to the rapidly growing field of submarine paleoseismology. IODP is uniquely positioned to address the complex feedback mechanisms between earthquake shaking and its manifestation in the marine archive, decipher related mass fluxes from the shallow to the deep see and to eventually provide longer records to constrain earthquake recurrence far beyond historical catalogues. Initially building on what sedimentary deposits were generated from the 2011 M9 Tohoku-oki earthquake, the Japan Trench is a promising study area to investigate earthquake-triggered sediment remobilization processes and how they become embedded in the stratigraphic record, and has thus been identified as a primary target for proposing giant piston coring within IODP. In this presentation we summarize recent results and available site survey data collected since the 2011 earthquake, comprising >50, 5-10m long piston and gravity cores from (i) trench-fill and graben-fill basin across the entire trench axis from 36° to 40.3° N (ii), the mid-slope terraces and (ii) from representative slope sites as potential source for sediment remobilization during earthquakes (2) nearly 2000km of high-resolution subbottom acoustic reflection data (Parasound) that reveals striking, up to several meter thick, acoustically transparent bodies interbedded in the otherwise parallel reflection pattern of the trench fill basins. Results from conventional coring covering the last 1500 years reveal good agreement between the sedimentary record and historical documents in the central part of the margin, and shed new lights on earthquake-triggered, gravity flow-driven supply of significant amount of pre-aged carbon to the hadal environment. New cores retrieved from the southern and northernmost part of the Japan Trench during the recent R/V Sonne expedition SO251 confirm the presence of repeated thick turbidite sequences to be further tested for correlation to historic earthquakes along different margin segments. All these observations underpin the great potential for deciphering earthquake related processes from the stratigraphic record of the small deep-sea trench-fill and graben-fill basins in the Japan Trench, the longer-term record of which is only accessible by giant-piston coring and drilling, as proposed by IODP in Proposal 866.

Biogeochemistry and geomicrobiology of cold-water coral carbonate mounds - lessons learned from IODP Expedition 307

NASA Astrophysics Data System (ADS)

Ferdelman, Timothy; Wehrmann, Laura; Mangelsdorf, Kai; Kano, Akihiro; Williams, Trevor; Jean-Pierre, Henriet

2010-05-01

Large mound structures associated with cold-water coral ecosystems commonly occur on the slopes of continental margins, for instance, west of Ireland in the Porcupine Seabight, the Gulf of Cadiz or the Straits of Florida. In the Porcupine Seabight over 1500 mounds of up to 5 km in diameter and 250 m height lie at water depths of 600 to 900 m. The cold-water coral reef ecosystems associated with these structures are considered to be "hotspots" of organic carbon mineralization and microbial systems. To establish a depositional and biogeochemical/diagenetic model for cold-water carbonate mounds, Challenger Mound and adjacent continental slope sites were drilled in May 2005 during IODP Expedition 307. One major objective was to test whether deep sub-surface hydrocarbon flow and enhanced microbial activity within the mound structure was important in producing and stabilizing these sedimentary structures. Drilling results showed that the Challenger mound succession (IODP Site U1317) is 130 to 150 meters thick, and mainly consists of floatstone and rudstone facies formed of fine sediments and cold-water branching corals. Pronounced recurring cycles on the scales of several meters are recognized in carbonate content (up to 70% carbonate) and color reflectance, and are probably associated with Pleistocene glacial-interglacial cycles. A role for methane seepage and subsequent anaerobic oxidation was discounted both as a hard-round substrate for mound initiation and as a principal source of carbonate within the mound succession. A broad sulfate-methane transition (approximately 50 m thick)within the Miocene sediments suggested that the zone of anaerobic oxidation of methane principally occurs below the moundbase. In the mound sediments, interstitial water profiles of sulfate, alkalinity, Mg, and Sr suggested a tight coupling between carbonate diagenesis and low rates of microbial sulfate reduction. Overall organic carbon mineralization within cold-water coral mound appeared to be dominated by low rates of iron- and sulfate-reduction that occur in discrete layers within the mound. This was consistent with distributions of total cell-counts, acetate turnover (Webster et al. 2009) and hydrogenase activity (Soffiento et al. 2009). However, biomarker lipid distributions suggested that the Miocene sediments underlying the mound, into which sulfate is diffusing, as well as the sediments from the non-cold water coral reference site (U1318) contain higher abundances of living microbes. The results obtained from Expedition 307 are consistent with a picture emerging from other biogeochemical studies of cold-water coral mound and reef sites. Unless impacted by some external forcing (e.g. fluid flow or erosion event), the microbial activity in the underlying cold-water coral mound sediments is largely decoupled from the highly diverse, active surface ecosystem. References: Soffiento B, Spivack AJ, Smith DC, and D'Hondt S (2009) Hydrogenase activity in deeply buried sediments of the Arctic and North Atlantic Oceans. Geomicro. J. 26: 537-545. Webster, G, Blazejak A, Cragg BA, Schippers A, Sass H, Rinna J, Tang X, Mathes F, Ferdelman TG., Fry JC, Weightman AJ, and Parkes RJ. 2009. Subsurface microbiology and biogeochemistry of a deep, cold-water carbonate mound from the Porcupine Seabight (IODP Expediton 307). Env. Microbiol., 11, 239-257, doi:10.1111/j.1462-2920.01759.x.

Stable isotope geochemistry of pore waters from the New Jersey shelf - No evidence for Pleistocene melt water

NASA Astrophysics Data System (ADS)

van Geldern, Robert; Hayashi, Takeshi; Böttcher, Michael E.; Mottl, Michael J.; Barth, Johannes A. C.; Stadler, Susanne

2013-04-01

Scientific drillings in the 1970s revealed the presence of a large fresh water lens below the New Jersey Shelf. The origin and age of this fresh water body is still under debate. Groundwater flow models suggest that the water mainly originates from glacial melt water that entered the ground below large continental ice sheets during the last glacial maximum (LGM), whereas other studies suggest an age up to late Miocene. In this study, interstitial water was sampled during the Integrated Ocean Drilling Program (IODP) expedition 313 "New Jersey Shallow Shelf" (Mountain et al., 2010) and analyzed for water chemistry and stable isotope ratios (van Geldern et al, 2013). The pore fluid stable isotope values define a mixing line with end members that have oxygen and hydrogen isotope values of -7.0‰ and -41‰ for fresh water, and -0.8‰ and -6‰ for saltwater, respectively. The analyses revealed the following sources of fluids beneath the shelf: (1) modern rainwater, (2) modern seawater, and (3) a brine that ascends from deep sediments. The stable isotope composition of the water samples indicates modern meteoric recharge from New Jersey onshore aquifers as the fresh-water end member. This contradicts earlier views on the formation of the New Jersey fresh water lens, as it does not support the ice-age-origin theory. The salt-water end member is identical to modern New Jersey shelf seawater. Lower core parts of the drilling sites are characterized by mixing with a brine that originates from evaporites in the deep underground and that ascends via faults into the overlying sediments. The geochemical data from this study may provide the basis for an approach to construct a transect across the New Jersey shallow shelf since they fill a missing link in the shelf's geochemical profile. They also lay foundations for future research on hardly explored near-shore freshwater resources. References Mountain, G. and the Expedition 313 Scientists, 2010, Proceedings of the Integrated Ocean Drilling Program, Volume 313, Tokyo, available at: http://publications.iodp.org/proceedings/313/313toc.htm. van Geldern, R., Hayashi, T., Böttcher, M. E., Mottl, M. J., Barth, J. A. C., and Stadler, S., 2013, Stable isotope geochemistry of pore waters and marine sediments from the New Jersey shelf: Methane formation and fluid origin: Geosphere, v. 9, no. 1, p. in press.

Fluid source inferred from strontium isotopes in pore fluid and carbonate recovered during Expedition 337 off Shimokita, Japan

NASA Astrophysics Data System (ADS)

Hong, W.; Moen, N.; Haley, B. A.

2013-12-01

IODP Expedition 337 was designed to understand the relationship between a deep-buried (2000 meters below seafloor) hydrocarbon reservoir off the Shimokita peninsula (Japan), and the microbial community that this carbon reservoir sustains at such depth. Understanding sources and pathways of flow of fluids that carry hydrocarbons, nutrients, and other reduced components is of particular interest to fulfilling the expedition objectives, since this migrating fluid supports microbial activity not only of the deep-seated communities but also to the shallow-dwelling organisms. To this aim, the concentration and isotopic signature of Sr can be valuable due to that it is relatively free from biogenic influence and pristine in terms of drill fluid contamination. From the pore water Sr profile, concentration gradually increases from 1500 to 2400 mbsf. The depth where highest Sr concentration is observed corresponds to the depths where couple layers of carbonate were observed. Such profile suggests an upward-migrating fluid carries Sr from those deep-seated carbonate layers (>2400 mbsf) to shallower sediments. To confirm this inference, pore water, in-situ formation fluid, and carbonate samples were analyzed for Sr isotopes to investigate the fluid source.

Initial report for magnetostratigraphy of IODP Site U1490

NASA Astrophysics Data System (ADS)

Kumagai, Y.; Hatfield, R. G.; Nakamura, N.; Yamazaki, T.

2017-12-01

We report preliminary paleomagnetic results from between 175-296 meters composite depth (Miocene in age) of IODP Site U1490 recovered during Expedition 363. Site U1490 is located at 05°48.95´N, 142°39.27´E (the northern edge of the Eauripik Rise in the equatorial Pacific) in 2341 m water depth. A primary objective of Expedition 363 was to reconstruct the regional climate variability within the Western Pacific Warm Pool (WPWP) in a broad spatial coverage and different temporal resolutions through the time interval from the middle Miocene to late Pleistocene. The recovered pelagic sediments contains calcareous and siliceous nannofossils with varying proportions of clay and ash. It is also characterized by current-controlled mud waves with gradually decreasing amplitude upsection (Rosenthal et al., 2017). Since deep water is enriched in dissolved oxygen due to downwelling in polar regions, the mud waves were probably formed in an oxic environment by bottom currents, hindering the dissolution of magnetic minerals in the sediments. Shipboard analysis revealed that magnetic minerals between 20-175 m composite depth at Site U1490 have been dissolved by diagenetic alteration and the paleomagnetic data is uninterpretable. But the upper 20 m and below 175 m have a stable magnetization that spans from present to early Pleistocene (0-1.9 Ma) and middle to late Miocene period ( 9-19 Ma), respectively. The latter is an exceptionally long-time range continuous core sample, so it provides us an opportunity to reveal long-range variations of paleomagnetic field. We will show stepwise alternate-field (AF) demagnetization of the natural remanent magnetization on U-channel samples from the composite stratigraphic section to establish magnetostratigraphy at this site.

IODP Expedition 303 (North Atlantic): Excursions and Reversals in the Brunhes and Matuyama Chrons

NASA Astrophysics Data System (ADS)

Channell, J. E.; Mazaud, A.; Stoner, J. S.

2005-12-01

The primary objective of IODP Expedition 303 (Sept.-Nov., 2004) was to recover complete and continuous records of Pliocene-Quaternary millennial-scale environmental and geomagnetic variability, and place these records into high-resolution isotopic and magnetic stratigraphies (including relative paleointensity). Some of the Exp. 303 site locations (Orphan Knoll, Eirik and Gardar Drifts, and DSDP Site 609) have already been instrumental in developing marine records of suborbital climate variability for the last climate cycle, and the goal of Exp. 303 was to extend the records back through the Quaternary and into the Pliocene. High mean sedimentation rates (15-20 cm/ky) at sites located on Orphan Knoll (Site U1302/3), Eirik Drift (Sites U1305 and U1306) and Gardar Drift (Site U1304) have resulted in shipboard records of excursions and reversals in the Brunhes and Matuyama Chrons. Site U1308 (DSDP Site 609) has lower mean sedimentation rate (7.9 cm/kyr) and extends the record into the Gauss Chron to ~3.1 Ma. Initial u-channel magnetic data support the existence of a number of polarity excursions in the Matuyama Chron, but only a single polarity excursion (Iceland Basin Event) has so far been observed in the Brunhes Chron. The Matuyama-Brunhes (M-B) polarity reversal yields virtual geomagnetic polar (VGP) paths that are reminiscent of those recovered from the northern Gardar and Bjorn drifts during ODP Leg 162. VGP clusters in the South Atlantic and off NE Asia accompany a Pacific loop, in what appears to be a repetitive but complex pattern for the M-B transition recorded in 9 holes from three Exp. 303 North Atlantic sites.

Paleoceanographic history of the Lower Bengal Fan during the last glacial cycle - IODP Expedition 354

NASA Astrophysics Data System (ADS)

Dekens, P. S.; Weber, M. E.; Lantzsch, H.; Das, S. K.; Williams, T.; Adhikari, R. R.; Jia, G.; Fox, L. R.; Ge, J.; Manoj, M. C.; Savian, J. F.; Reilly, B. T.; Selkin, P. A.; Meynadier, L.; Spiess, V.; France-Lanord, C.; Sharma, B.

2015-12-01

IODP Expedition 354 drilled a ~320 km long transect of seven sites on the Lower Bengal Fan at 8o N in the Northern Indian Ocean. The sediments cores recovered record a complex relationship between turbiditic and hemipelagic environments. This variability offers a unique opportunity to link our understanding of tectonic and terrestrial processes with climate and oceanography. With the exception the westernmost Site U1454, all sites show a several meter thick, hemipelagic top layer, usually representing Late Quaternary sediment. We present physical, geochemical and stable isotopic properties of this interval to establish a time frame and assess the paleoceanographic development of the region during the last glacial cycle. We sampled Site U1452C-1H continuously for the uppermost 480 cm of hemipelagic sediment in 2-cm increments. Preliminary results indicate the Toba Ash 1 (0.74 ka) is a distinct time marker in all physical properties. Furthermore, wet-bulk density as well as color reflectance b* (the red-green component) and L* (the lightness) show a dominant precession cyclicity. Hence, we are able to provide an insolation-tuned chronology for the last 200 ka (MIS1 - 7) as a preliminary age model. These records agree well with d18O records retrieved from Chinese caves. We will present a preliminary paleoceanographic proxy data to reconstruct sea-surface temperature (SST), sea-surface salinity (SSS), ice volume, marine biological productivity, nutrient supply, and deep-water circulation. These oceanographic and climate conditions are linked to changes in monsoonal strength and terrestrial input using sedimentary proxies to reconstruct chemical weathering and sediment sources and transport time. This work addresses one of the primary cruise objectives - linking monsoon variability, regional and global climate, and Bay of Bengal sediment deposition.

Unveiling climate and ice-sheet history from drilling in high-latitude margins and future perspectives

NASA Astrophysics Data System (ADS)

Escutia Dotti, Carlota

2010-05-01

Polar ice is an important component of the climate system, affecting global sea level, ocean circulation and heat transport, marine productivity, and albedo. During the last decades drilling in the Arctic (IODP ACEX and Bering Expeditions) and in Antarctica (ODP Legs 178, 188, IODP Expedition 318 and ANDRILL) has revealed regional information about sea ice and ice sheets development and evolution. Integration of this data with numerical modeling provide an understanding of the early development of the ice sheets and their variability through the Cenozoic. Much of this work points to atmospheric CO2 and other greenhouse gases concentrations as important triggering mechanism driving the onset of glaciation and subsequent ice volume variability. With current increasing atmospheric greenhouse gases concentrations resulting in rapidly rising global temperatures, studies of polar climates become increasingly prominent on the research agenda. Despite of the relevance of the high-latitudes in the global climate systems, the short- and long-term history of the ice sheets and sea-ice and its relationships with paleoclimatic, paleoceanographic, and sea level changes is still poorly understood. A multinational, multiplatform scientific drilling strategy is being developed to recover key physical evidence from selected high-latitude areas. This strategy is aimed at addressing key knowledge gaps about the role of polar ice in climate change, targeting questions such as timing of events, rates of change, tipping points, regional variations, and northern vs. southern hemispheres (in phase or out-of-phase) variability. This data is critical to provide constrains to sea-ice and ice sheet models, which are the basis for forecasting the future of the cryosphere in a warming world.

Geochemistry of the Bonin Fore-arc Volcanic Sequence: Results from IODP Expedition 352

NASA Astrophysics Data System (ADS)

Godard, M.; Ryan, J. G.; Shervais, J. W.; Whattam, S. A.; Sakuyama, T.; Kirchenbaur, M.; Li, H.; Nelson, W. R.; Prytulak, J.; Pearce, J. A.; Reagan, M. K.

2015-12-01

The Izu-Bonin-Mariana intraoceanic arc system, in the western Pacific, results from ~52 My of subduction of the Pacific plate beneath the eastern margin of the Philippine Sea plate. Four sites were drilled south of the Bonin Islands during IODP Expedition 352 and 1.22 km of igneous basement was cored upslope to the west of the trough. These stratigraphically controlled igneous suites allow study of the earliest stages of arc development from seafloor spreading to convergence. We present the preliminary results of a detailed major and trace element (ICPMS) study on 128 igneous rocks drilled during Expedition 352. Mainly basalts and basaltic andesites were recovered at the two deeper water sites (U1440 and U1441) and boninites at the two westernmost sites (U1439 and U1442). Sites U1440 and U1441 basaltic suites are trace element depleted (e.g. Yb 4-6 x PM); they have fractionated REE patterns (LREE/HREE = 0.2-0.4 x C1-chondrites) compared to mid-ocean ridge basalts. They have compositions overlapping that of previously sampled Fore-Arc Basalts (FAB) series. They are characterized also by an increase in LILE contents relative to neighboring elements up-section (e.g. Rb/La ranging from <1 to 3-7 x PM at Site U1440) suggesting a progressive contamination of their source by fluids. This process in turn may have favored melting and efficient melt extraction from the source and thus its extreme depletion. Boninites are depleted in moderately incompatible elements with a decrease in their contents up-section (e.g. Yb = ~6.2 to 2.8 x C1-chondrite at Site U1439). These changes in trace element contents are associated with the development of a positive Zr-Hf anomaly relative to neighboring elements and a strong increase in LILE (e.g., Zr/Sm=~1 to 2.6 x PM and Rb/La=1-2 to 10-18). The progressive upward depletion of boninitic lavas could reveal the incorporation of harzburgitic residues from FAB generation into their mantle source.

Post-magmatic tectonic deformation of the outer Izu-Bonin-Mariana forearc system: initial results of IODP Expedition 352

NASA Astrophysics Data System (ADS)

Kurz, Walter; Ferré, Eric C.; Robertson, Alastair; Avery, Aaron; Christeson, Gail L.; Morgan, Sally; Kutterorf, Steffen; Sager, William W.; Carvallo, Claire; Shervais, John; Party IODP Expedition 352, Scientific

2015-04-01

IODP Expedition 352 was designed to drill through the entire volcanic sequence of the Bonin forearc. Four sites were drilled, two on the outer fore arc and two on the upper trench slope. Site survey seismic data, combined with borehole data, indicate that tectonic deformation in the outer IBM fore arc is mainly post-magmatic. Post-magmatic extension resulted in the formation of asymmetric sedimentary basins such as, for example, the half-grabens at sites 352-U1439 and 352-U1442 located on the upper trench slope. Along their eastern margins these basins are bounded by west-dipping normal faults. Sedimentation was mainly syn-tectonic. The lowermost sequence of the sedimentary units was tilted eastward by ~20°. These tilted bedding planes were subsequently covered by sub-horizontally deposited sedimentary beds. Based on biostratigraphic constraints, the minimum age of the oldest sediments is ~ 35 Ma; the timing of the sedimentary unconformities lies between ~ 27 and 32 Ma. At sites 352-U1440 and 352-U1441, located on the outer forearc, post-magmatic deformation resulted mainly in strike-slip faults possibly bounding the sedimentary basins. The sedimentary units within these basins were not significantly affected by post-sedimentary tectonic tilting. Biostratigraphic ages indicate that the minimum age of the basement-cover contact lies between ~29.5 and 32 Ma. Overall, the post-magmatic tectonic structures observed during Expedition 352 reveal a multiphase tectonic evolution of the outer IBM fore arc. At sites 352-U1439 and 352-U1442, shear with dominant reverse to oblique reverse displacement was localized along distinct subhorizontal cataclastic shear zones as well as steeply dipping slickensides and shear fractures. These structures, forming within a contractional tectonic regime, were either re-activated as or cross-cut by normal-faults as well as strike-slip faults. Extension was also accommodated by steeply dipping to subvertical mineralized veins and extensional fractures. Faults observed at sites 352-U1440 and 352-U1441 show mainly strike-slip. The sediments overlying the igneous basement, of maximum Late Eocene to Recent age, document ash and aeolian input, together with mass wasting of the fault-bounded sediment ponds.

Fluid inclusion petrography and microthermometry of the Cocos Ridge hydrothermal system, IODP Expedition 344 (CRISP 2), Site U1414

NASA Astrophysics Data System (ADS)

Brandstätter, J.; Kurz, W.; Krenn, K.; Micheuz, P.

2015-12-01

We present new data from microthermometric analyses of fluid inclusions entrapped in hydrothermal veins within lithified sediments and Cocos Ridge (CCR) basalt from IODP Expedition 344 site U1414 (Costa Rica) and concern on a primary task of Expedition 344, i.e. to evaluate fluid/rock interaction, the hydrologic system, and the geochemical processes (indicated by composition and volume of fluids) active within the incoming Cocos Plate. Mineralization of the veins and crosscutting relationships gives constraints for the different generation of veins. Calcium carbonate, commonly aragonite in the upper part and calcite in the lower part of the igneous basement, is usually present in veins as a late phase following the quartz precipitation and the clay minerals formation. The sequence of vein generations in the lithified sediments close to the contact within the CCR basalt is characterized by smaller veins filled by quartz, followed by massive intersecting calcite veins. A high fluid pressure can be concluded, due to wall rock fragments embedded within the filling and fractured mineral grains in the ground mass, which are close to the veins. This requires that the magmatic basement and the lithified sediments were covered by sequences of low permeability sediments forming a barrier that enabled build up elevated fluid pressure. The investigation of fluid inclusions in the lowest units of borehole 344-U1414, give clues about the source of the fluids and about the vein evolution within the incoming Cocos Plate close to Middle American Trench. The microthermometric analyses of the primary, almost aqueous, inclusions indicate a temperature range during entrapment between 200 and 420°C. The data indicate that seawater within the Cocos Ridge aquifer communicated with high-temperature fluids and/or were modified by heat advection. We consider the Galapagos hotspot and/ or the Cocos-Nazca spreading center as heat source. Fluids originated from mobilized sediment pore water and invaded seawater. Isotope and heat flow data indicate a deep fluid source within the Cocos Plate oceanic crust too.

Characterization of Fractures in the Chicxulub Peak Ring: Preliminary Results from IODP/ICDP Expedition 364

NASA Astrophysics Data System (ADS)

McCall, N.; Gulick, S. P. S.; Morgan, J. V.; Hall, B. J.; Jones, L.; Expedition 364 Science Party, I. I.

2017-12-01

During Expedition 364, IODP/ICDP drilled the peak ring of the Chicxulub impact crater at Site M0077, recovering core from 505.7 to 1334.7 mbsf. The core has been imaged via X-ray Computer Tomography (CT) as a noninvasive method to create a 3-dimensional model of the core, providing information on the density and internal structure at a 0.3 mm resolution. Results from the expedition show that from 748 mbsf and deeper the peak ring is largely composed of uplifted and fractured granitic basement rocks originally sourced from approximately 8-10 km depth. Impact crater modeling suggests the peak ring was formed through dynamic collapse of a rebounding central peak within 10 minutes of impact, requiring the target rocks to temporarily behave as a viscous fluid. The newly recovered core provides a rare opportunity to investigate the cratering process, specifically how the granite was weakened, as well as the extent of the hydrothermal system created after the impact. Based on the CT data, we identify four classes of fractures based on their CT facies deforming the granitoids: pervasive fine fractures, discrete fine fractures, discrete filled fractures, and discrete open fractures. Pervasive fine fractures were most commonly found proximal to dikes and impact melt rock. Discrete filled fractures often displayed a cataclastic texture. We present density trends for the different facies and compare these to petrophysical properties (density, NGR, P-wave seismic velocity). Fractured areas have a lower density than the surrounding granite, as do most filled fractures. This reduction suggests that fluid migrating through the peak ring in the wake of the impact either deposited lower density minerals within the fractures and/or altered the original fracture fill. The extent and duration of fluid flow recorded in these fractures will assist in the characterization of the post-impact hydrothermal system. Future work includes combining information from CT images with thin sections and plug samples at similar depths, refinement of CT facies characterization, examining cross-cutting relationships to determine timing constraints of deformation processes, and measurement of the orientation of the fractures.

A brittle (normal?) shear zone cored in Site C0002 of Nankai Trough Seismogenic Zone Experiment (IODP Expedition 348)

NASA Astrophysics Data System (ADS)

Crespo-Blanc, Ana; Sample, James; Brown, Kevin; Otsubo, Makoto; Yamamoto, Yuzuru

2016-04-01

Integrated Ocean Discovery Program (IODP) Expedition 348, which belongs to the Nankai Trough Seismogenic Zone Experiment, conducted riser-drilling to make deeper an existing hole at Site C0002, up to 3058.5 meters below seafloor (mbsf). This site is located 80 km SE of the Kii Peninsula (Japan) in the Kumano forearc basin, in turn situated on top of the Nankai accretionary prism. Cuttings (875.5-3058.5 mbsf) and cores (2163.0-2217.5 mbsf) were collected in the upper Miocene to Pliocene turbiditic silty claystone with few intercalations of sandstone which characterize the accretionary prism lithological units. A remarkably preserved fault zone has been cored around 2205 mbsf (core section Hole C0002P-348-5R-4). It is characterized by 34 cm of fault breccia, in which an anastomosed cataclastic foliation is present. The rocks of the damaged zone are formed by silty claystone with an incipient scaly fabric and scarce levels of sandstones. Extra-large thin sections were made along the whole core section. In the brittle shear zone, they reveal a catalogue of deformation structures characteristic of a high structural level. In particular, almond-type structures and arrays of microfaults cutting the stratification are the most common structures and outline the cataclastic foliation. The occurrence of calcite veins in the recovered cores is limited to this fault zone, which is indicative of its role as fluid path, accompanied by carbonate cementation. Generally fault veins have lower δ18O values than carbonate cements in the sedimentary matrix, consistent with veins forming at higher temperatures and/or from a fluid more strongly depleted in 18O. A continuum of the relationships between calcite veins and cataclastic deformation is observed, from veins that precipitated early in the fault history, with calcite grains broken during subsequent deformation, to late veins which seal the almond-type structures within the claystones. The geometry of the calcite grains within the veins and the relationship between the veins and the wall rock indicate that the mechanism that actuate during the vein formation is that of crack-seal. It took place along variable growth planes inside the vein and the wall rock (localized and delocalized stretching veins, respectively), which result in asymmetric syntaxial veins. All the observed microfaults produced lengthening of the markers. Together with the mesoscopic criteria (according to the visual core descriptions made onboard), this would indicate that, in its present-day position, this brittle shear zone is associated with a normal fault. Nevertheless, it is not discarded that it could be an early thrust rotated after its development. Acknowledgements: This research used samples provided by IODP. Grants RNM-215 and 451 ("Junta de Andalucía", Spain) and CGL2013-46368-P ("Ministerio de Economía y Competitividad", Spain) supported this study.

Stress and Pore Pressure Measurement in IODP Riser Drilling: An Example from Expedition 319, Kumano Basin offshore SW Honshu, Japan

NASA Astrophysics Data System (ADS)

Saffer, D. M.; McNeill, L. C.; Byrne, T. B.; Araki, E.; Flemings, P. B.; Conin, M.; Eguchi, N. O.; Takahashi, K.; Toczko, S.; Boutt, D. F.; Doan, M.; Kano, Y.; Ito, T.; Lin, W.

2009-12-01

In summer 2009, Integrated Ocean Drilling Program (IODP) Expedition 319 drilled a 1600 m deep riser borehole (Site C0009) in the Kumano Basin offshore SW Japan, to investigate the properties, structure and state of stress in the hanging wall above the subduction plate boundary. The first riser-based scientific drilling in IODP history allowed us to make several new scientific measurements including in situ stress magnitude, pore pressure and permeability using the Modular Formation Dynamics Tester (MDT) wireline tool, and measurement of minimum stress magnitude from Leak-off Tests (LOT). In addition, continuous monitoring of mud weight, mud gas, annular pressure, and mud losses provided data to constrain formation pore fluid pressure and stress. At Site C0009, we conducted 2 LOTs below a casing shoe at 708.6 m depth and 11 successful MDT measurements, including 9 single probe tests to measure pore pressure and fluid mobility and 2 dual packer tests: 1 to measure permeability by a drawdown test, and 1 to measure in situ stress. Measured pore pressures are approximately hydrostatic to 1463.7 m depth. We observed only minor gas shows when drilling ahead (as in-place methane was liberated from the rock at the bit) but little or no gas during pipe connections. This indicates that the borehole mud pressure exceeded the formation pore pressure, and is consistent with the MDT measurements. Permeabilities range from ~10-16 m2 - 10-14 m2, and the observed variation is consistent with lithologic changes defined in gamma ray logs. The MDT measurement at 874.3 mbsf and the LOT at 708.6 m yield values for the least principal stress of 34.8 MPa and 30.2 MPa, respectively. Both are less than the vertical stress (Sv) computed from density logs. Partial mud circulation losses occurred when the borehole mud pressure exceeded the leak-off stress measured at the base of the casing shoe; this provides an additional indirect constraint on Shmin magnitude. Mud pressure slightly in excess of the leak-off stress may have also generated poorly-developed drilling-induced tensile fractures (DITF) observed in resistivity image logs between ~750 - 1000 m. From the presence of DITF, Shmin measurements, and assuming a rock tensile strength of 1 MPa, we determine that SHmax is 35.1 MPa for the MDT stress measurement, and 30.2 MPa for the LOT. Using the MDT measurement of Shmin, the resulting principal stress magnitudes define a strike-slip faulting regime with effective stresses of Shmax’ = 14 MPa, Sv' = 7.3 MPa, and Shmin’ = 6.4 MPa. In contrast, using the LOT measurement of Shmin, the stress magnitudes indicate a normal faulting regime in which Sv’ = 6.2 MPa, Shmax’ = 2.8 MPa, and Shmin’ = 2.6 MPa.

Evolution of biogeochemical cycling of phosphorus during 45~50 Ma revealed by sequential extraction analysis of IODP Expedition 302 cores from the Arctic Ocean

NASA Astrophysics Data System (ADS)

Hashimoto, S.; Yamaguchi, K. E.; Takahashi, K.

2012-12-01

The modern Arctic Ocean plays crucial roles in controlling global climate system with the driving force of global thermohaline circulation through the formation of dense deep water and high albedo due to the presence of perennial sea-ice. However, the Arctic sea-ice has not always existed in the past. Integrated Ocean Drilling Program (IODP) Expedition 302 Arctic Coring Expedition (ACEX) has clarified that global warming (water temperature: ca. 14~16○C) during 48~49 Ma Azolla Event induced the loss of sea-ice and desalination of surface ocean, and that sea-ice formed again some million years later (45 Ma). In the Arctic Ocean, warming and cooling events repeated over and over (e.g., Brinkhuis et al., 2006; Moran et al., 2006; März et al., 2010). Large variations in the extent of thermohaline circulation through time often caused stagnation of seawater and appearance of anaerobic environment where hydrogen sulfide was produced by bacterial sulfate reduction. Ogawa et al. (2009) confirmed occurrence of framboidal pyrite in the ACEX sediments, and suggested that the Arctic Ocean at the time was anoxic, analogous to the modern Black Sea, mainly based on sulfur isotope analysis. To further clarify the variations in the nutrient status of the Arctic Ocean, we focus on the geochemical cycle of phosphorus. We performed sequential extraction analysis of sedimentary phosphorus in the ACEX sediments, using the method that we improvped based on the original SEDEX method by Ruttenberg (1992) and Schenau et al. (2000). In our method, phosphorus fractions are divided into five forms; (1) absorbed P, (2) Feoxide-P, (4) carbonate fluorapatite (CFAP) + CaCO3-P + hydroxylapatite (HAP), (4) detrital P, and (5) organic P. Schenau et al. (2000) divided the (3) fraction into non-biological CFAP and biological HAP and CaCO3-P. When the Arctic Ocean was closed and in its warming period, the water mass was most likely stratified and an anaerobic condition would have prevailed where bacterial sulfate reduction was active. In this case, most of the phosphorus in sediment was stored as organic P, which was originally derived as sinking particles of detrital plankton from the surface ocean. Increased rainfalls during such a warming period would have enhanced continental weathering and delivery of phosphorus to the surface ocean, and biological activity using increased amounts of phosphorus supply would also have increased. Feoxide-P is considered to be less important as a sink for phosphorus because of the likely formation of pyrite through the reductive dissolution of Fe oxide. CFAP could be a sink for phosphorus, because the formation of CFAP tends to increase with increasing age and depth.

Provenance of Continental Margin Sediments in the East China Sea, Results from IODP Expedition 346

NASA Astrophysics Data System (ADS)

Anderson, C. H.; Dunlea, A. G.; Murray, R. W.; Tada, R.; Alvarez Zarikian, C. A.

2016-12-01

Sedimentation in the East China Sea (ECS) is driven largely by fluvial and eolian fluxes that are likely influenced by the East Asian Monsoon (EAM). Seasonal shifts and long term trends in the atmospheric and precipitation regimes over Asia are recorded in the inorganic chemistry of the sediment of the ECS and other Asian coastal seas. Changes in the intensity and timing of the EAM over a variety of time scales may impact the relative proportion of fluvial and eolian inputs into the ECS, and perhaps even their individual sources. We utilize bulk sediment recovered from IODP Sites U1428 and U1429 in the ECS during IODP Expedition 346 in 2013 to examine changes in the EAM over the past 400ky. Sites U1428 and U1429 are located in the northernmost portion of the ECS in the Danjo Basin, and are separated by 7.4 km. We present major, trace and rare earth element (REE) data for 83 bulk sediment samples analyzed by ICP-ES and ICP-MS, and interpret this data set using a variety of geochemical approaches in addition to multivariate statistics (Q-mode Factor Analyses, Multiple Linear Regressions) to investigate the provenance of terrigenous material during the Pleistocene. We focus on a suite of nine elements that are associated with terrigenous components (Al, Ti, Sc, Cr, Ni, Zn, Rb, Th, La), and that are expected to reflect potential changes in provenance. At both sites average downhole major element ratios exhibit limited variation, but indicate mixing between multiple compositional sources. Ternary diagrams utilizing La-Th-Sc and Rb-Sc-Zn diagrams suggest crustal mixing between three or more sources including upper continental and mafic inputs. Our multivariate statistical data exploration consistently indicates four statistically robust end members explaining 99% of total data variability when we treat these sites as a combined regional signal. Considering each site separately, the four end members are joined by additional fifth end member at each site; highlighting variation in Cr or Ti depending on the site. Inputs from different upper crustal sources and most likely including refractory sands are the most likely contributors to the bulk sediment. Additional results from further statistical analysis will also be presented.

Quaternary paleoceanography of the central Arctic based on Integrated Ocean Drilling Program Arctic Coring Expedition 302 foraminiferal assemblages

USGS Publications Warehouse

Cronin, T. M.; Smith, S.A.; Eynaud, F.; O'Regan, M.; King, J.

2008-01-01

The Integrated Ocean Drilling Program (IODP) Arctic Coring Expedition (ACEX) Hole 4C from the Lomonosov Ridge in the central Arctic Ocean recovered a continuous 18 in record of Quaternary foraminifera yielding evidence for seasonally ice-free interglacials during the Matuyama, progressive development of large glacials during the mid-Pleistocene transition (MPT) ???1.2-0.9 Ma, and the onset of high-amplitude 100-ka orbital cycles ???500 ka. Foraminiferal preservation in sediments from the Arctic is influenced by primary (sea ice, organic input, and other environmental conditions) and secondary factors (syndepositional, long-term pore water dissolution). Taking these into account, the ACEX 4C record shows distinct maxima in agglutinated foraminiferal abundance corresponding to several interglacials and deglacials between marine isotope stages (MIS) 13-37, and although less precise dating is available for older sediments, these trends appear to continue through the Matuyama. The MPT is characterized by nearly barren intervals during major glacials (MIS 12, 16, and 22-24) and faunal turnover (MIS 12-24). Abundant calcareous planktonic (mainly Neogloboquadrina pachyderma sin.) and benthic foraminifers occur mainly in interglacial intervals during the Brunhes and very rarely in the Matuyama. A distinct faunal transition from calcareous to agglutinated foraminifers 200-300 ka in ACEX 4C is comparable to that found in Arctic sediments from the Lomonosov, Alpha, and Northwind ridges and the Morris Jesup Rise. Down-core disappearance of calcareous taxa is probably related to either reduced sea ice cover prior to the last few 100-ka cycles, pore water dissolution, or both. Copyright 2008 by the American Geophysical Union.

Complexity in Matuyama-Brunhes polarity transitions from North Atlantic IODP/ODP deep-sea sites

NASA Astrophysics Data System (ADS)

Channell, J. E. T.

2017-06-01

Integrated Ocean Drilling Program (IODP) Expedition 303 to the North Atlantic provided 16 records of the Matuyama-Brunhes polarity transition (MBT), based on u-channel and discrete samples, from holes drilled at three sites (Sites U1304, U1305 and U1306) that have mean Brunhes sedimentation rates of 16-18 cm/kyr. The MBT occurs during the transition from marine isotope stage (MIS) 19c to MIS 18e, with mid-point at ∼773 ka, and a transition duration of ∼8 kyr. Combining the new MBT records, including one new record for the top Jaramillo, with previously published North Atlantic MBT records (ODP Sites 983, 984 and 1063) yields a total of more than 20 high-sedimentation-rate polarity transition records. The MBT yields a repetitive pattern of transitional field states as virtual geomagnetic poles (VGPs) move from high southern latitudes to loop over the Pacific, group in NE Asia, and transit into the mid-latitude South Atlantic before reaching high latitudes in the Northern Hemisphere. The VGPs for the top Jaramillo transition feature a loop over the Pacific, then a NE Asia group before transit over the Indian Ocean to high southerly latitudes. The North Atlantic MBT records described here contrast with longitudinally-constrained VGP paths for the MBT, indicating that relatively low sedimentation rate (∼4 cm/kyr) records of the MBT are heavily smoothed by the remanence acquisition process and do not adequately represent the MBT field. The VGPs at the MBT and top Jaramillo, as measured in the North Atlantic, have similarities with excursion (Iceland Basin) VGP paths, and were apparently guided by maxima in downward vertical flux similar to those seen in the modern non-dipole (ND) field, implying longevity in ND features through time.

Dynamics of large submarine landslide from analyzing the basal section of mass-transport deposits sampled by IODP Nankai Trough Submarine Landslide History (NanTroSLIDE)

NASA Astrophysics Data System (ADS)

Strasser, M.; Dugan, B.; Henry, P.; Jurado, M. J.; Kanagawa, K.; Kanamatsu, T.; Moore, G. F.; Panieri, G.; Pini, G. A.

2014-12-01

Mulitbeam swath bathymetry and reflection seismic data image large submarine landslide complexes along ocean margins worldwide. However, slope failure initiation, acceleration of motion and mass-transport dynamics of submarine landslides, which are all key to assess their tsunamigenic potential or impact on offshore infrastructure, cannot be conclusively deduced from geometric expression and acoustic characteristics of geophysical data sets alone, but cores and in situ data from the subsurface are needed to complement our understanding of submarine landslide dynamics. Here we present data and results from drilling, logging and coring thick mass-transport deposits (MTDs) in the Nankai Trough accretionary prism during Integrated Ocean Drilling Program (IODP) Expeditions 333 and 338. We integrate analysis on 3D seismic and Logging While Drilling (LWD) data sets, with data from laboratory analysis on core samples (geotechnical shear experiments, X-ray Computed Tomography (X-CT), Scanning Electron Microscopy (SEM) of deformation indicators, and magnetic fabric analysis) to study nature and mode of deformation and dynamics of mass transport in this active tectonic setting. In particular, we show that Fe-S filaments commonly observed on X-ray CT data of marine sediments, likely resulting from early diagenesis of worm burrows, are folded in large MTDs and display preferential orientation at their base. The observed lineation has low dip and is interpreted as the consequence of shear along the basal surface, revealing a new proxy for strain in soft sediments that can be applied to cores that reach through the entire depth of MTDs. Shear deformation in the lower part of thick MTDs is also revealed from AMS data, which - in combination with other paleo-magnetic data - is used to reconstruct strain and transport direction of the landslides.

In situ stress and pore pressure in the Kumano Forearc Basin, offshore SW Honshu from downhole measurements during riser drilling

NASA Astrophysics Data System (ADS)

Saffer, D. M.; Flemings, P. B.; Boutt, D.; Doan, M.-L.; Ito, T.; McNeill, L.; Byrne, T.; Conin, M.; Lin, W.; Kano, Y.; Araki, E.; Eguchi, N.; Toczko, S.

2013-05-01

situ stress and pore pressure are key parameters governing rock deformation, yet direct measurements of these quantities are rare. During Integrated Ocean Drilling Program (IODP) Expedition #319, we drilled through a forearc basin at the Nankai subduction zone and into the underlying accretionary prism. We used the Modular Formation Dynamics Tester tool (MDT) for the first time in IODP to measure in situ minimum stress, pore pressure, and permeability at 11 depths between 729.9 and 1533.9 mbsf. Leak-off testing at 708.6 mbsf conducted as part of drilling operations provided a second measurement of minimum stress. The MDT campaign included nine single-probe (SP) tests to measure permeability and in situ pore pressure and two dual-packer (DP) tests to measure minimum principal stress. Permeabilities defined from the SP tests range from 6.53 × 10-17 to 4.23 × 10-14 m2. Pore fluid pressures are near hydrostatic throughout the section despite rapid sedimentation. This is consistent with the measured hydraulic diffusivity of the sediments and suggests that the forearc basin should not trap overpressures within the upper plate of the subduction zone. Minimum principal stresses are consistently lower than the vertical stress. We estimate the maximum horizontal stress from wellbore failures at the leak-off test and shallow MDT DP test depths. The results indicate a normal or strike-slip stress regime, consistent with the observation of abundant active normal faults in the seaward-most part of the basin, and a general decrease in fault activity in the vicinity of Site C0009.

Chronostratigraphic framework for the IODP Expedition 318 cores from the Wilkes Land Margin: Constraints for paleoceanographic reconstruction

NASA Astrophysics Data System (ADS)

Tauxe, L.; Stickley, C. E.; Sugisaki, S.; Bijl, P. K.; Bohaty, S. M.; Brinkhuis, H.; Escutia, C.; Flores, J. A.; Houben, A. J. P.; Iwai, M.; Jiménez-Espejo, F.; McKay, R.; Passchier, S.; Pross, J.; Riesselman, C. R.; Röhl, U.; Sangiorgi, F.; Welsh, K.; Klaus, A.; Fehr, A.; Bendle, J. A. P.; Dunbar, R.; Gonzàlez, J.; Hayden, T.; Katsuki, K.; Olney, M. P.; Pekar, S. F.; Shrivastava, P. K.; van de Flierdt, T.; Williams, T.; Yamane, M.

2012-06-01

The Integrated Ocean Drilling Program Expedition 318 to the Wilkes Land margin of Antarctica recovered a sedimentary succession ranging in age from lower Eocene to the Holocene. Excellent stratigraphic control is key to understanding the timing of paleoceanographic events through critical climate intervals. Drill sites recovered the lower and middle Eocene, nearly the entire Oligocene, the Miocene from about 17 Ma, the entire Pliocene and much of the Pleistocene. The paleomagnetic properties are generally suitable for magnetostratigraphic interpretation, with well-behaved demagnetization diagrams, uniform distribution of declinations, and a clear separation into two inclination modes. Although the sequences were discontinuously recovered with many gaps due to coring, and there are hiatuses from sedimentary and tectonic processes, the magnetostratigraphic patterns are in general readily interpretable. Our interpretations are integrated with the diatom, radiolarian, calcareous nannofossils and dinoflagellate cyst (dinocyst) biostratigraphy. The magnetostratigraphy significantly improves the resolution of the chronostratigraphy, particularly in intervals with poor biostratigraphic control. However, Southern Ocean records with reliable magnetostratigraphies are notably scarce, and the data reported here provide an opportunity for improved calibration of the biostratigraphic records. In particular, we provide a rare magnetostratigraphic calibration for dinocyst biostratigraphy in the Paleogene and a substantially improved diatom calibration for the Pliocene. This paper presents the stratigraphic framework for future paleoceanographic proxy records which are being developed for the Wilkes Land margin cores. It further provides tight constraints on the duration of regional hiatuses inferred from seismic surveys of the region.

Chronostratigraphic framework for the IODP Expedition 318 cores from the Wilkes Land Margin: Constraints for paleoceanographic reconstruction

USGS Publications Warehouse

Tauxe, L.; Stickley, C.E.; Sugisaki, S.; Bijl, P.K.; Bohaty, S.M.; Brinkhuis, H.; Escutia, C.; Flores, J.A.; Houben, A.J.P.; Iwai, M.; Jiménez-Espejo, F.; McKay, R.; Passchier, S.; Pross, J.; Riesselman, Christina; Röhl, U.; Sangiorgi, F.; Welsh, K.; Klaus, A.; Fehr, A.; Bendle, J.A.P.; Dunbar, R.; Gonzàlez, J.; Hayden, T.; Katsuki, K.; Olney, M.P.; Pekar, S.F.; Shrivastava, P.K.; van de Flierdt, T.; Williams, T.; Yamane, M.

2012-01-01

The Integrated Ocean Drilling Program Expedition 318 to the Wilkes Land margin of Antarctica recovered a sedimentary succession ranging in age from lower Eocene to the Holocene. Excellent stratigraphic control is key to understanding the timing of paleoceanographic events through critical climate intervals. Drill sites recovered the lower and middle Eocene, nearly the entire Oligocene, the Miocene from about 17 Ma, the entire Pliocene and much of the Pleistocene. The paleomagnetic properties are generally suitable for magnetostratigraphic interpretation, with well-behaved demagnetization diagrams, uniform distribution of declinations, and a clear separation into two inclination modes. Although the sequences were discontinuously recovered with many gaps due to coring, and there are hiatuses from sedimentary and tectonic processes, the magnetostratigraphic patterns are in general readily interpretable. Our interpretations are integrated with the diatom, radiolarian, calcareous nannofossils and dinoflagellate cyst (dinocyst) biostratigraphy. The magnetostratigraphy significantly improves the resolution of the chronostratigraphy, particularly in intervals with poor biostratigraphic control. However, Southern Ocean records with reliable magnetostratigraphies are notably scarce, and the data reported here provide an opportunity for improved calibration of the biostratigraphic records. In particular, we provide a rare magnetostratigraphic calibration for dinocyst biostratigraphy in the Paleogene and a substantially improved diatom calibration for the Pliocene. This paper presents the stratigraphic framework for future paleoceanographic proxy records which are being developed for the Wilkes Land margin cores. It further provides tight constraints on the duration of regional hiatuses inferred from seismic surveys of the region.

Vegetation and climate development on the Atlantic Coastal Plain during the late Mid-Miocene Climatic Optimum (IODP Expedition 313)

NASA Astrophysics Data System (ADS)

Prader, Sabine; Kotthoff, Ulrich; McCarthy, Francine; Greenwood, David

2015-04-01

The major aims of IODP Expedition 313 are estimating amplitudes, rates and mechanisms of sea-level change and the evaluation of sequence stratigraphic facies models that predict depositional environments, sediment compositions, and stratal geometries in response to sea-level change. Cores from three Sites (313-M0027, M0028, and M0029) from the New Jersey shallow shelf (water depth approximately 35 m) were retrieved during May to July 2009, using an ECORD "mission-specific" jack-up platform. We have investigated the palynology of sediment cores from Site M0027, 45 km off the present-day coast of New Jersey. For this study, we have focused on pollen studies for the second half of the Mid-Miocene Climatic Optimum (MMCO) and the subsequent transition to cooler conditions (ca. 15 to 13 million years before present). Transport-caused bias of the pollen assemblages was identified via the analysis of the terrestrial/marine palynomorph ratio and these results were considered when interpreting palaeo-vegetation from the pollen data. Pollen preservation in the interval analyzed herein was generally very good. Pollen grains were analyzed via both light and scanning electron microscopy. For most samples, the pollen assemblages were not highly diverse. The most abundant taxa through all samples were Quercus (oak) and Carya (hickory). Typical wetland elements like Cyperaceae, Taxodium (cypress), Nyssa (tupelo tree) and taxa today growing in the tropics and subtropics like Sapotaceae, Symplocaceae, Arecaceae (palm trees) and Alangium, which indicate particularly warm climate conditions, were only sporadically found, but indicate warmer phases during the second half of the MMCO. Herbal pollen was generally rare, but members of the Asteraceae, Apiaceae, and Ericaceae families, together with infrequent occurences of Poaceae pollen indicate the presence of areas with open vegetation. The Mid-Miocene pollen assemblages reflect a vegetation in the hinterland of the New Jersey shelf which was reminiscent of Oligocene and early Miocene ecosystems analyzed in previous studies (e.g. Kotthoff et al. 2014). The ecosystem was characterized by oak-hickory forests which probably dominated in the lowlands, while frequent occurrence of conifer pollen (Pinus, Picea, Abies, Sciadopitys, and Tsuga canadensis) indicate that conifer forests prevailed in higher altitudes during the MMCO. We assume that the Miocene uplift of the Appalachian Mountains (e.g. Gallen et al., 2013) led to the proliferation of mountainous taxa and thus to an increase of related pollen taxa in the palynological record. References: Gallen, S. F., Wegmann, K. W., Bohnenstieh, D. W. R.: Miocene rejuvenation of topographic relief in the southern Appalachians, GSA Today, 23, 4-10, 2013. Kotthoff, U., McCarthy, F.M.G., Greenwood, D.R., Müller-Navarra, K., Prader, S., Hesselbo, S.P., (2014): Vegetation and climate development on the Atlantic Coastal Plain from 33 to 13 million years ago (IODP expedition 313). Climate of the Past 10, 1523-1539.

New insights from IODP Expedition 340 offshore Montserrat: First drilling of large volcanic island landslides

NASA Astrophysics Data System (ADS)

Talling, Peter; Le Friant, Anne; Ishizuka, Osamu; Watt, Sebastian; Coussens, Maya; Jutzeler, Martin; Wall-Palmer, Deborah; Palmer, Martin; Cassidy, Michael; Kataoka, Kyoko; Endo, Daisuko; McCanta, Molly; Trofimovs, Jessica; Hatfield, Robert; Stinton, Adam; Lebas, Elodie; Boudon, Georges; Expedition 340 Shipboard Science Party, IODP

2015-04-01

Montserrat now provides one of the most complete datasets for understanding the character and tempo of hazardous events at volcanic islands. Much of the erupted material ends up offshore, and this offshore record may be easier to date due to intervening hemiplegic sediments between event beds. The offshore dataset includes the first scientific drilling of volcanic island landslides during IODP Expedition 340, together with an unusually comprehensive set of shallow sediment cores and 2-D and 3-D seismic surveys. Most recently in 2013, Remotely Operated Vehicle (ROV) dives mapped and sampled the surface of the main landslide deposits. This contribution aims to provide an overview of key insights from ongoing work on IODP Expedition 340 Sites offshore Montserrat.Key objectives are to understand the composition (and hence source), emplacement mechanism (and hence tsunami generation) of major landslides, together with their frequency and timing relative to volcanic eruption cycles. The most recent major collapse event is Deposit 1, which involved ~1.8 km cubed of material and produced a blocky deposit at ~12-14ka. Deposit 1 appears to have involved not only the volcanic edifice, but also a substantial component of a fringing bioclastic shelf, and material locally incorporated from the underlying seafloor. This information allows us to test how first-order landslide morphology (e.g. blocky or elongate lobes) is related to first-order landslide composition. Preliminary analysis suggests that Deposit 1 occurred shortly before a second major landslide on the SW of the island (Deposit 5). It may have initiated English's Crater, but was not associated with a major change in magma composition. An associated turbidite-stack suggests it was emplaced in multiple stages, separated by at least a few hours and thus reducing the tsunami magnitude. The ROV dives show that mega-blocks in detail comprise smaller-scale breccias, which can travel significant distances without complete disintegration. Landslide Deposit 2 was emplaced at ~130ka, and is more voluminous (~8.4km cubed). It had a much more profound influence on the magmatic system, as it was linked to a major explosive mafic eruption and formation of a new volcanic centre (South Soufriere Hills) on the island. Site U1395 confirms a hypothesis based on the site survey seismic data that Deposit 2 includes a substantial component of pre-existing seafloor sediment. However, surprisingly, this pre-existing seafloor sediment in the lower part of Deposit 2 at Site U1395 is completely undeformed and flat lying, suggesting that Site U1395 penetrated a flat lying block. Work to date material from the upper part of U1396, U1395 and U1394 will also be summarised. This work is establishing a chronostratigraphy of major events over the last 1 Ma, with particularly detailed constraints during the last ~250ka. This is helping us to understand whether major landslides are related to cycles of volcanic eruptions.

Revised Late Oligocene to Early Miocene magnetic stratigraphy recorded by drift sediments at Sites U1405 and U1406, IODP Expedition 342 (Newfoundland, NW Atlantic)

NASA Astrophysics Data System (ADS)

van Peer, Tim; Xuan, Chuang; Wilson, Paul; Liebrand, Diederik; Lippert, Peter

2015-04-01

The nannofossil oozes drilled at IODP Expedition 342 (Paleogene Newfoundland Sediment Drifts) Sites U1405 and U1406 provide an exceptional sedimentary archive of the Late Oligocene to Early Miocene due to high sedimentation rates (2-6 cm/kyr at U1406 and up to 20 cm/kyr at U1405) and their ideal location below the Deep Western Boundary Current. These drift sediment sequences provide a unique opportunity to study the Oligocene-Miocene Transition (OMT) and Mi1-event (a transient 1‰ positive oxygen isotope excursion) at an unprecedented resolution from a Northern Hemisphere perspective. The exact timing of the OMT and its rate of change require a reliable and high-resolution magnetic stratigraphic age control, as Chron C6Cn with its three subchrons roughly spans the Mi1 event and the reversal C6Cn.2n/C6Cn.2r defines the Oligocene-Miocene boundary. Natural Remanent Magnetisation (NRM) was measured on 140 m of u-channel samples at U1405 and 190 m at U1406. The u-channel sample based magnetostratigraphy is in good agreement with that based on the shipboard data and reveal distinctive well-defined patterns of normal and reversed polarities, which can be correlated to the Geomagnetic Polarity Time Scale between C6Bn.2n and C9n (ca. 22.2 to 27 Ma) at U1406 and between C6Bn.2n and C6Cr (ca. 22.2 to 23.5 Ma) at U1405. Furthermore, putative cryptochrons in Chron C6Br and C7Ar, previously reported at Site U1334 (IODP Expedition 320), are observed in the u-channel magnetic stratigraphy for Sites U1405 and U1406. Anhysteretic Remanent Magnetisation (ARM) intensity variations are combined with X-Ray Fluorescence (XRF) generated elemental measurements to refine the shipboard splice of both U1405 and U1406. Latest Oligocene to earliest Miocene splice refinements are complicated by the presence of large-scale stratigraphic gaps (up to 25 m at U1405) unrelated to drilling disturbances. The depth and estimated age of these stratigraphic gaps vary from hole to hole, and do not appear to impact the completeness of the spliced magnetostratigraphic record. Rock and mineral magnetic studies of selected samples are currently ongoing to characterise the magnetic mineralogy of the sediments and how it changes across the stratigraphic gaps and intervals with contrasting lithological and/or palaeomagnetic properties. These data will help us understand the origin of the palaeomagnetic signal and test its reliability, while providing insights on the nature of the observed stratigraphic gaps and how they relate to global climate dynamics of the OMT and the Deep Western Boundary Current.

High sedimentation rates and thrust fault modulation: Insights from ocean drilling offshore the St. Elias Mountains, southern Alaska

NASA Astrophysics Data System (ADS)

Worthington, Lindsay L.; Daigle, Hugh; Clary, Wesley A.; Gulick, Sean P. S.; Montelli, Aleksandr

2018-02-01

The southern Alaskan margin offshore the St. Elias Mountains has experienced the highest recorded offshore sediment accumulation rates globally. Combined with high uplift rates, active convergence and extensive temperate glaciation, the margin provides a superb setting for evaluating competing influences of tectonic and surface processes on orogen development. We correlate results from Integrated Ocean Drilling Program (IODP) Expedition 341 Sites U1420 and U1421 with regional seismic data to determine the spatial and temporal evolution of the Pamplona Zone fold-thrust belt that forms the offshore St. Elias deformation front on the continental shelf. Our mapping shows that the pattern of active faulting changed from distributed across the shelf to localized away from the primary glacial depocenter over ∼300-780 kyrs, following an order-of-magnitude increase in sediment accumulation rates. Simple Coulomb stress calculations show that the suppression of faulting is partially controlled by the change in sediment accumulation rates which created a differential pore pressure regime between the underlying, faulted strata and the overlying, undeformed sediments.

Outreach Aboard the JOIDES Resolution During IODP Exp. 360: Bringing Cutting Edge Research on Mid Ocean Ridge Processes to Classrooms Worldwide

NASA Astrophysics Data System (ADS)

Kavanagh, L.; Martinez, A. O.; Burgio, M.; Zhang, J.; Expedition 360 Scientists, I.

2016-12-01

In order to increase classroom engagement for the next generation of scientists, teachers must include current research in their curriculum. The JOIDES Resolution offers this opportunity to teachers worldwide. We recently served as four Education and Outreach Officers during Exp. 360: Southwest Indian Ridge Lower Crust and Moho. Our aim was to communicate the goals of the expedition to students and the general public through webcasts, social media, videos, and interviews. Prior to the expedition, I visited a number of schools in Texas and shared my upcoming experience with 800 teachers and students. Webcasts hosted during the expedition were tailored to the teacher's specifications of subject area and grade level. Students and teachers were able to witness cutting edge science during a tour of the ship and ask questions of those directly involved in the research. Lessons, resources, and videos featuring the scientific activities taking place and highlighting the workings of a research vessel were developed and will be featured at science teacher conferences at the state and national level. Upon my return home I visited schools that participated in webcasts and provided samples of peripheral rock material for instructional purposes. This expedition has also led to post cruise collaboration with some of the Expedition 360 scientists. My students will have the opportunity to do research with the microbiologists along the Rio Grande River and at Texas A&M University. Expedition 360 has opened up a multitude of opportunities for my students and those around the world that participated in the live webcasts. I was able to reach out to the same students multiple times during this experience which made it possible for them to connect with the science before, during, and after the expedition. These types of opportunities will inspire the next generation of scientists who will make advances towards new understandings of Earth's processes.

An initial examination of carbonate variability in the western equatorial Pacific: XRF results from the lower to middle Miocene of IODP Site U1490

NASA Astrophysics Data System (ADS)

Valerio, D. A.; Kulhanek, D. K.; Rosenthal, Y.; Holbourn, A. E.

2017-12-01

International Ocean Discovery Program (IODP) Expedition 363 sought to determine the nature of and driving forces behind climate variability in the Western Pacific Warm Pool (WPWP) region throughout the Neogene on millennial, orbital, and geologic timescales. Our research focuses on the Miocene (19-9 Ma) sediment record from IODP Site U1490 to examine changes in carbonate production and burial in the WPWP as a record of variations in the regional/global carbon cycle. This interval is of particular interest because it spans the Middle Miocene Climatic Optimum, the Middle Miocene Climate Transition, and the late Miocene carbonate crash. Site U1490 is located on the northern edge of Eauripik Rise at 05°58.95'N, 142°39.27'E in the northern part of the WPWP. At 2341 m water depth, today the site is bathed in Upper Circumpolar Deepwater. Miocene sediment at Site U1490 primarily consists of clay-bearing to clay-rich foraminifer-rich nannofossil ooze, although biogenic silica (primarily radiolaria) is a significant component in the lowermost part of the record. The sedimentation rate in the early to middle Miocene was very low (<1 cm/kyr), increasing to 1.6 cm/kyr in the late Miocene. Initial shipboard results show an average calcium carbonate content of 87 wt% throughout the site, with the most significant variations in the lower to middle Miocene, where contents range from 20 to 85 wt%. We collected X-ray fluorescence (XRF) data at 1 cm resolution along the composite stratigraphic section over the 19-9 Ma interval to obtain a qualitative measure of the bulk chemistry of the sediment. We will use the weight percent calcium carbonate of discrete samples to calibrate the XRF data to generate a high-resolution carbonate record. We observe cyclical variations in the Ca/Ba, which may reflect variations in productivity and/or dissolution through this interval, although additional work is needed to fully interpret these data. Ultimately our research will allow for comparison between records obtained from these cores located in the western equatorial Pacific to those obtained in the eastern and central Pacific, which will better elucidate the nature of the carbon system during the Miocene.

Broader Impact and the Arctic Coring Expedition of Summer 2004: A Science Teacher Brings the Pole to the Public

NASA Astrophysics Data System (ADS)

Couchon, K. M.

2006-12-01

The ARMADA Project, funded by NSF and administered through the University of Rhode Island Office of Marine Programs, pairs 12-14 teachers with ocean, polar, and environmental scientists each year, affording these teachers an authentic research experience. One middle-school science teacher, Kathleen Couchon of Narragansett, Rhode Island, participated in the IODP Arctic Coring Expedition (ACEX) in the summer of 2004. Sailing for 6 weeks aboard the Swedish Icebreaker Oden, Kathleen participated in many aspects of the polar ocean-drilling expedition and was accepted by scientists and crew alike as part of the international science party. Upon return to the classroom, Kathleen found multiple opportunities to share her Arctic research experiences through effective public outreach both within and outside of the educational community. In the classroom, she has developed and implemented inquiry-based activities, allowing her students the opportunity to function as scientists themselves. Mentoring new science teachers within the district and presenting multi- media presentations to other teachers and students at the Narragansett Pier Middle School and Narragansett High School in Rhode Island, provided a wider audience for this important polar geoscience enterprise. An expanded circle of impact was gained through presentations at local district, state, and national teacher gatherings, including two National Science Teacher Association annual conventions and a high school audience at Arcadia High School in Phoenix, Arizona. Within the community-at-large, Kathleen has impacted diverse audiences including the Girl Scouts, the Rotary Club, and senior citizen groups - all enthusiastically receptive and appreciative of hearing the scientific news of research from the North Pole. These experiences have served to establish a linkage between the scientific community and the public, with a teacher-researcher sharing and interpreting the scientific research goals and methodologies, as well as results, in layman's terminology. This presentation will highlight some of the effective outreach ideas that fostered a greater public appreciation for the polar scientific endeavors of the ACEX cruise.

Towards understanding the role of the Bering Strait in the Plio-Pleistocene climate change

NASA Astrophysics Data System (ADS)

Okazaki, Y.; Onodera, J.; Teraishi, A.; Suto, I.

2011-12-01

The Bering Strait is the gateway between Pacific and Arctic, plays an important role in global freshwater cycle and eventually influences on climate change. The glacial Pacific Ocean had well-ventilated and nutrient-depleted glacial North Pacific Intermediate Water (GNPIW) above ~2000 m. GNPIW is a thicker and more deeply penetrating water mass than today's North Pacific Intermediate Water (NPIW). The source of GNPIW was likely in the Bering Sea based on neodymium isotope evidence. During Heinrich Event 1 in the early deglacial period, deep water extending to a depth of ~2500 m formed in the North Pacific. Modeling simulations suggest that a closed Bering Strait is essentially required for salinity built-up in the North Pacific to form the deep water. First opening of the Bering Strait was suggested to be in the latest Miocene and have repeated opening and closure by eustatic sea-level change associated with climate changes. However, our knowledge on the history about the opening/closure is limited due to lack of appropriate samples. During the IODP Expedition 323, Pliocene to Pleistocene marine sediment was continuously recovered from the Bering Sea. At the northern Bering continental slope sites (U1343 and U1344), the period with high abundance of diatom species Neodenticula seminae is terminated around 0.8-0.9 Ma, which appears to coincide with the Mid-Pleistocene Transition (MPT). While Neodenticula seminae is an endemic and predominant diatom in the modern subarctic Pacific and the Aleutian basin of the Bering Sea, the occurrence of this species is reported from the sediments between 0.84 and 1.25 Ma in the northern North Atlantic. This suggests a significantly intensified Arctic Throughflow and adaptive environment for N. seminae production from the Bering Strait to the Greenland Sea during the MPT. The observations of hydrography and the modern re-appearance of this taxon since 1999 in the Labrador Sea due to the melting of the Arctic Sea ice also suggests the specific requirements by this species: low salinity and high dissolved silicon concentrations. During the glacial cycles of the last 800 kyr, a limited input of Pacific water into the Arctic Ocean or disconnection was suggested by decreased abundances of N. seminae. Furthermore, repeated abundance peaks of radiolarian species Cycladophora davisiana, indicating cold and well ventilated intermediate water, suggest enhancement of intermediate to deep water formation in the Bering Sea during glacial periods, when the Bering Strait was closed. This research used samples and data provided by the IODP. We acknowledge the IODP Expedition 323 Shipboard Scientists.

The Successful Deployment of a New Sub-Seafloor Observatory

NASA Astrophysics Data System (ADS)

Lado Insua, T.; Moran, K.; Kulin, I.; Farrington, S.; Newman, J. B.; Riedel, M.; Iturrino, G. J.; Masterson, W. A.; Furman, C. R.; Klaus, A.; Storms, M.; Attryde, J.; Hetmaniak, C.; Huey, D.

2013-12-01

The Simple Cabled Instrument for Measuring Parameters In-Situ (SCIMPI) is a new ocean observatory instrument designed to study dynamic processes in the sub-seafloor. The first SCIMPI prototype comprises nine modules that collect time series measurements of temperature, pressure and electrical resistivity of sediments at pre-selected depths below seafloor. These modules are joined in an array by flexible cables. Floats are attached to the cables of the system to keep the cabling taught against the weight of a sinker bar at the bottom of the string. The system was designed for deployment through drillpipe using D/V JOIDES Resolution. SCIMPI is designed for sediments that will collapse around the observatory after deployment. After five years in development, SCIMPI was successfully deployed within the NEPTUNE Canada observatory in May 2013. The IODP Expedition 341S took place on the Cascadia Margin. The deployment Site U1416 is within an active gas hydrate vent field. Spacing of SCIMPI modules was tailored to measure parameters in the accreted sediment and above and below the Bottom Simulating Reflector (BSR). The location of the modules was dimensioned based on a multivariate analysis of physical properties derived from IODP boreholes located nearby. Members of the SCIMPI team, science party, technical support, crew and participants of the School of Rock assembled the instrument on deck during the days leading up to the deployment. During deployment, SCIMPI was connected to the Multi-Function-Telemetry-Module (from LDEO) and was lowered through drillpipe on the wireline logging cable. SCIMPI communicated data to a shipboard computer until its release, providing assurance that measurements were active on all sensors. The observatory was released with the Electronic Release System (ERS) and the drillpipe was pulled out of the borehole. A camera system was used to check on the installation immediately after deployment. An Ocean Networks Canada expedition revisited the site a month later to assess the borehole collapse around SCIMPI. Its four year battery life will allow SCIMPI to record data on its command module while waiting to be connected to the NEPTUNE Canada observatory in 2014. The modular design of SCIMPI allows adapting its configuration for different situations and environments. SCIMPI is now available for exploring other dynamic sub-seafloor settings in future expeditions.

Defining Lithological Units by Cuttings, Core and Logging Data at Site C0009A in the Nankai Trough, Japan: IODP Expedition 319

NASA Astrophysics Data System (ADS)

Efimenko, N.; Schleicher, A. M.; Buchs, D. M.; Buret, C.; Kawabata, K.; Boutt, D. F.; Underwood, M.; Araki, E.; Byrne, T. B.; McNeill, L. C.; Saffer, D. M.; Eguchi, N. O.; Takahashi, K.; Toczko, S.; Scientists, E.

2009-12-01

The use of cuttings as an alternative or addition to core material is broadly debated in on-shore and off-shore drilling expeditions. Expedition 319 is the first IODP based Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) project using the riser-drilling method to collect cutting and core samples for scientific studies. One major scientific objective for this site was to characterise the lithology and deformation history of the Kumano forearc basin sediments and its underlying units through comparison of (i) cuttings, (ii) core, (iii) measurements while drilling, and (iv) wireline logging data. Cuttings were retrieved from each 5 m intervals from 703.9 to 1604 m, and cores were recovered from 1509.7 to 1593.9 m below sea floor. As core availability was limited, the study of cuttings was a crucial step in improving our understanding of their potential and limits for lithostratigraphical interpretations compared to core. Mineralogical and chemical analysis of cuttings and core, wireline logging data, and gamma ray data from MWD were available to define four lithostratigraphic units. These units are composed of mud and mudstone with coarser silty and sandy interbeds, and volcanic ash/tuff. Consistency between unit boundaries determined from cuttings and those determined from log data is good in terms of depth, with typical mismatches of less than 10m. Three significant problems affecting the preservation of cuttings were (1) mixing of cuttings as they travel from the drill face to the surface, (2) alteration of natural mineral and structure signatures, and (3) possible contamination from natural clay minerals with the polymer/bentonite drill mud. These difficulties can be overcome in part through the analysis of cuttings of similar sizes (1-4 mm), guided by the analyses of bulk cuttings. A more accurate quantitative characterisation of cuttings through the use of digital imaging might improve the description of lithofacies. Although the quality of cuttings is affected by caving and drilling mud contamination, our results clearly indicate that cuttings retrieval is a viable alternative to coring in ocean drilling. However, to improve the precision of lithostratigraphical observations and interpretations in critical intervals, the study of cores is needed.

Structure and builtup of the Middle Bengal Fan at 8°N from multichannel seismic surveys and the IODP Expedition 354 drilling transect

NASA Astrophysics Data System (ADS)

Spiess, V.; Bergmann, F.; Schwenk, T.; Lantzsch, H.; Bahk, J. J.; Weber, M. E.; France-Lanord, C.; Klaus, A.

2016-12-01

IODP Expedition 354 to the Bengal Fan drilled a 320 km long e-W transect at 8°N with 7 drill sites, fully covering the uppermost 150-200 meters of fan deposits at distances of 50 km, originating from Himalayan mountain ranges and the Ganges-Brahmaputra river system. A major goal of this transect approach was to ensure a continuous record of turbiditic material delivered over the last appx. 1 million year, considering frequent longitudinal depocenter shifts of the active channel. By extensively utilizing the new half-APC coring technique, high quality and high recovery cores could be retrieved representing a wide range of grain sizes from hemipelagic deposits through clay rich turbidites to coarse silt and sandy units. Up to medium sand grain sizes were retrieved within the basal units of levees, which correspond to high-reflectivity units in high-resolution multichannel seismic profiles. Finely laminated sections with mm to cm-thick turbidites represents levee formations. At Site U1453 for example, core logging and downhole logging data confirm the representative sampling based on a very good match of several physical property data sets. An expanded section was cored at Site U1454, where the presumably currently active channel has built a levee, which likely represents major sediment supply within the last 30 kyr. A spatial grid of seismic and echosounder data in the vicinity of the active channel reveals a high spatial variability in sedimentation rates and distinct depocenter shifts in response to changes in channel geometry. Site U1452 has provided a full record a levee growth including interlevee sedimentation, sandy basal units characterized by a lobe formation, and a pronounced fining upward trend following the phase of channel erosion and levee builtup. From all sites, detailed comparisons of physical and sedimentological shipboard results with seismic data will be presented. Expedition 354 has provided a unique sample and data set to better understand fan deposition and channel-levee growth including silt and sand grain sizes. It will also provide valuable constraints on the volume, nature and composition of suspension flows contributing to fan growth in the Middle Bengal Fan.

Permeability structure and its influence on microbial activity at off-Shimokita basin, Japan

NASA Astrophysics Data System (ADS)

Tanikawa, W.; Yamada, Y.; Sanada, Y.; Kubo, Y.; Inagaki, F.

2016-12-01

The microbial populations and the limit of microbial life are probably limited by chemical, physical, and geological conditions, such as temperature, pore water chemistry, pH, and water activity; however, the key parameters affecting growth in deep subseafloor sediments remain unclarified (Hinrichs and Inagaki 2012). IODP expedition 337 was conducted near a continental margin basin off Shimokita Peninsula, Japan to investigate the microbial activity under deep marine coalbed sediments down to 2500 mbsf. Inagaki et al. (2015) discovered that microbial abundance decreased markedly with depth (the lowest cell density of <1 cell/cm3 was recorded below 2000 mbsf), and that the coal bed layers had relatively higher cell densities. In this study, permeability was measured on core samples from IODP Expedition 337 and Expedition CK06-06 in the D/V Chikyu shakedown cruise. Permeability was measured at in-situ effective pressure condition. Permeability was calculated by the steady state flow method by keeping differential pore pressure from 0.1 to 0.8 MPa.Our results show that the permeability for core samples decreases with depth from 10-16 m2 on the seafloor to 10-20 m2 at the bottom of hole. However, permeability is highly scattered within the coal bed unit (1900 to 2000 mbsf). Permeabilities for sandstone and coal is higher than those for siltstone and shale, therefore the scatter of the permeabilities at the same unit is due to the high variation of lithology. The highest permeability was observed in coal samples and this is probably due to formation of micro cracks (cleats). Permeability estimated from the NMR logging using the empirical parameters is around two orders of magnitude higher than permeability of core samples, even though the relative permeability variation at vertical direction is quite similar between core and logging data.The higher cell density is observed in the relatively permeable formation. On the other hand, the correlation between cell density, water activity, and porosity is not clear. On the assumption that pressure gradient is constant through the depth, flow rate can be proportional to permeability of sediments. Flow rate probably restricts the availability of energy and nutrient for microorganism, therefore permeability might have influenced on the microbial activity in the coalbed basin.

Anoxia and high primary production in the Paleogene central Arctic Ocean: First detailed records from Lomonosov Ridge

NASA Astrophysics Data System (ADS)

Stein, Ruediger; Boucsein, Bettina; Meyer, Hanno

2006-09-01

Except for a few discontinuous fragments of the Late Cretaceous/Early Cenozoic climate history and depositional environment, the paleoenvironmental evolution of the pre-Neogene central Arctic Ocean was virtually unknown prior to the IODP Expedition 302 (Arctic Ocean Coring Expedition-ACEX) drilling campaign on Lomonosov Ridge in 2004. Here we present detailed organic carbon (OC) records from the entire ca. 200 m thick Paleogene OC-rich section of the ACEX drill sites. These records indicate euxinic "Black Sea-type" conditions favorable for the preservation of labile aquatic (marine algae-type) OC occur throughout the upper part of the early Eocene and the middle Eocene, explained by salinity stratification due to freshwater discharge. The superimposed short-term ("Milankovitch-type") variability in amount and composition of OC is related to changes in primary production and terrigenous input. Prominent early Eocene events of algae-type OC preservation coincide with global δ13C events such as the PETM and Elmo events. The Elmo δ13C Event has been identified in the Arctic Ocean for the first time.

Global Sea-level Changes Revealed in the Sediments of the Canterbury Basin, New Zealand: IODP Expedition 317

NASA Astrophysics Data System (ADS)

McHugh, C. M.; Fulthorpe, C.; Blum, P.; Rios, J.; Chow, Y.; Mishkin, K.

2012-12-01

Continental margins are composed of thick sedimentary sections that preserve the record of local processes modulated by global sea-level (eustatic) changes and climate. Understanding this regional variability permits us to extract the eustatic record. Integrated Ocean Drilling Program Expedition 317 drilled four sites in the offshore Canterbury Basin, eastern South Island of New Zealand, in water depths of 85 m to 320 m. One of the objectives of the expedition was to understand the influence of eustasy on continental margins sedimentation and to test the concepts of sequence stratigraphy. A high-resolution multiproxy approach that involves geochemical elemental analyses, lithostratigraphy and biostratigraphy is applied to understand the margin's sedimentation for the past ~5 million years. Multichannel seismic data (EW00-01 survey) provide a seismic sequence stratigraphic framework against which to interpret the multiproxy data. The mid- to late Pleistocene sedimentation is characterized by variable lithologies and changing facies. However, elemental compositions and facies follow predictable patterns within seismic sequences. Oxygen isotope measurements for the latest Pleistocene indicate that 100 ky Milankovich astronomical forcing controlled this variability. In contrast, Pliocene and early Pleistocene sediments are composed of repetitive siliciclastic and carbonate mud lithologies with less facies variability. Results of our analyses suggest that repetitive alternations of green and gray mud were deposited during warmer and cooler periods, respectively. Oxygen isotopes suggest that this cyclicity may reflect 40 ky Milankovich forcing. Ocean Drilling Program Legs 150 and 174A drilled on the New Jersey continental margin with similar objectives to those of Expedition 317. Results from this northern and southern hemisphere drilling reveal that eustasy, controlled by Milankovich forcing, strongly influences margin sedimentation and the formation of basin-wide unconformities. However, the correlation between eustasy and seismic sequence formation is not always one to one. High sedimentation rates in the Pleistocene offshore Canterbury Basin record a one- to-one correlation between glacioeustasy and seismic sequences, and in some sequences possibly a higher order frequency. But this is not the case for offshore New Jersey, where accumulation rates were lower and only the uppermost seismic sequences represent 100 ky cycles. Furthermore, Pliocene sedimentation in the Canterbury Basin was also controlled by eustasy, but does not show a one-to-one correlation between Milankovich cycles and seismic stratigraphy. Northern and southern hemisphere comparisons provide a powerful tool to better understand controls on regional sedimentation and extract a global signal.

Ecosystem reconstructions for the hinterland of the Atlantic Coastal Plain during the late Mid-Miocene Climatic Optimum (IODP Expedition 313)

NASA Astrophysics Data System (ADS)

Prader, Sabine; Kotthoff, Ulrich; McCarthy, Francine; Greenwood, David

2016-04-01

During IODP Expedition 313, cores from three Sites (313-M0027, M0028, and M0029) from the New Jersey shallow shelf (water depth approximately 35 m) were retrieved in 2009. We have investigated the palynology of sediment cores from Site M0027, 45 km off the present-day coast of New Jersey in order to reconstruct environmental and climate change in the region during the second half of the Mid-Miocene Climatic Optimum (MMCO) and the subsequent transition to cooler conditions (ca. 15 to 13 million years before present). Transport-caused bias of the pollen assemblages was identified via the analysis of the terrestrial/marine palynomorph ratio and these results were considered when interpreting palaeo-vegetation from the pollen data. Pollen preservation in the interval analyzed herein was generally very good. Pollen grains were analyzed via both light and scanning electron microscopy. In the analyzed samples, angiosperm tree pollen grains were most abundant and probably formed the main vegetation zone in the lowland during the MMCO. The pollen-based results point to the presence of a deciduous-evergreen mixed forest that was characterised by e.g. Quercus, Carya, Liquidambar, Juglans, Pterocarya, Tilia, Engelhardia. Frequent conifer pollen grains indicate that highland forests with e.g. Pinus, Cathaya, and Picea were present the hinterland of the New Jersey shelf. Typical wetland elements like Nyssa and Taxodium as well as herbal taxa like Polygonum and Polygala were generally rare. The pollen-based climate reconstructions for the hinterland oft the New Jersey shallow shelf document a warm temperate climate without winterfrost and relatively high precipitation through the year during this time. Our results imply that the vegetation and regional climate in the hinterland of the New Jersey shelf did not react as sensitively to the cooling phase following the MMCO as other regions in North America or Europe.

Meso- and microscale structures related to post-magmatic deformation of the outer Izu-Bonin-Mariana fore arc system: preliminary results from IODP Expedition 352

NASA Astrophysics Data System (ADS)

Micheuz, P.; Kurz, W.; Ferre, E. C.

2015-12-01

IODP Expedition 352 aimed to drill through the entire volcanic sequence of the Bonin fore arc. Four sites were drilled, two on the outer fore arc and two on the upper trench slope. Analysis of structures within drill cores, combined with borehole and site survey seismic data, indicates that tectonic deformation in the outer Izu-Bonin-Mariana fore arc is mainly post-magmatic, associated with the development of syn-tectonic sedimentary basins. Within the magmatic basement, deformation was accommodated by shear along cataclastic fault zones, and the formation of tension fractures, hybrid (tension and shear) fractures, and shear fractures. Veins commonly form by mineral filling of tension or hybrid fractures and, generally, show no or limited observable macroscale displacement along the fracture plane. The vein filling generally consists of (Low Mg-) calcite and/or various types of zeolite as well as clay. Vein frequency varies with depth but does not seem to correlate with the proximity of faults. This may indicate that these veins are genetically related to hydrothermal activity taking place shortly after magma cooling. Host-rock fragments are commonly embedded within precipitated vein material pointing to a high fluid pressure. Vein thickness varies from < 1 mm up to 15 mm. The wider veins appear to have formed in incremental steps of extension. Calcite veins tend to be purely dilational at shallow depths, but gradually evolve towards oblique tensional veins at depth, as shown by the growth of stretched calcite and/or zeolites (idiomorphic and/or stretched) with respect to vein margins. With increasing depth, the calcite grains exhibit deformation microstructures more frequently than at shallower core intervals. These microstructures include thin twinning (type I twins), increasing in width with depth (type I and type II twins), curved twins, and subgrain boundaries indicative of incipient plastic deformation.

Carbonate and silicate cementation of siliciclastic sediments of the New Jersey shelf (IODP Expedition 313): relation with organic matter diagenesis and submarine groundwater discharge

NASA Astrophysics Data System (ADS)

Pierre, Catherine; Blanc-Valleron, Marie-Madeleine; Boudouma, Omar; Lofi, Johanna

2017-12-01

The New Jersey continental shelf extends 150 km off the shoreline. During IODP Expedition 313, siliciclastic deposits of late Eocene to late Pleistocene age were drilled down to 631, 669 and 755 m below seafloor at sites 27A, 28A and 29A respectively in very shallow waters (33.5 to 36 m depth). Pore water salinities display multilayered brackish-salty-brine units 10 to 170 m thick, where low-salinity water is preferentially stored in fine-grained sediments. The sharp boundaries of these buried aquifers are often marked by cemented layers a few centimetres thick. The mineralogy and scanning electron microscope observations of these layers show two phases of cementation by authigenic minerals: (1) the early carbonate cement is frequently associated with pyrite, and (2) the late silicate cement infills the residual porosity. The isotopic compositions of the carbonate cements vary widely: -2.4 < δ18O ‰ VPDB < +2.8; -15.1 < δ13C ‰ VPDB < +15.6. The δ18O values indicate that the carbonate cements precipitated with pore waters comprising variable mixtures of seawater and 18O-depleted fresh water originating from submarine groundwater discharge. The δ13C values of the carbonate cements are related to organic matter diagenesis, providing 13C-depleted dissolved inorganic carbon during bacterial sulphate reduction and anaerobic oxidation of methane, and 13C-rich dissolved inorganic carbon during methanogenesis. The diagenetic cementation processes included chemical weathering of reactive silicate minerals by the CO2-rich pore waters issued from organic matter diagenesis that released bicarbonate, cations and dissolved silica, which were further precipitated as carbonate and silicate cements. The estimated range of temperature (18±4 °C) during carbonate precipitation is consistent with carbonate cementation at moderate burial depths; however, silicate cementation occurred later during diagenesis at deeper burial depths.

Stratigraphic Evolution of Brazos-Trinity Basin IV, Western Gulf of Mexico: Preliminary Results of IODP Expedition 308

NASA Astrophysics Data System (ADS)

Pirmez, C.; Behrmann, J.; Flemings, P. B.; John, C.

2005-12-01

IODP Expedition 308 drilled three sites across Brazos-Trinity Basin IV, at the terminal end of a system of four salt-withdrawal intra-slope basins offshore Texas. A 175 m thick succession of sand-rich turbidite fans, mass-transport deposits and hemipelagic sediments was deposited within the last ~120 ka in Basin IV, as recorded at Site U1320. Pre-fan deposits dating back to MIS 6 form a conformable succession of laminated and bioturbated clays, deposited from distal turbidity currents and/or river plumes. The pre-fan succession is capped by a hemipelagic clay interpreted to represent the high stand of sea level during MIS 5e. The basal turbidite deposits in the basin are mud-rich, with the exception of the very first turbidity currents to enter the basin. This initial pulse, possibly derived from failure of older shelf edge deposits, accumulated an ~8 m thick sand-rich interval. A pause in turbidity current influx lasted 30 to 40 kyrs, beginning a few thousand years before ash layer Y8 dated at 84 ka and the Emiliana huxleyi acme. During MIS 3 to MIS 2 sand-rich fans containing 5-25 m thick packets of very fine to lower medium sand beds accumulated up to 130 m of sediments. A 2-3 m thick microfossil-rich clay marks the end of turbidity current influx into the basin during the Holocene. The sedimentary record of Brazos-Trinity Basin IV shows that the accumulation of turbidites in the terminal end of this source to sink depositional system reflects a complex interaction between the availability of material and the initiation of flows at the source near the shelf edge, the interaction of turbidity currents with complex slope topography, and the effects of salt tectonics and flow processes on modifying this topography. The initial results indicate that sealevel changes alone cannot explain the sedimentation patterns observed in the basin.

Unusual Physical Properties of the Chicxulub Crater Peak Ring: Results from IODP/ICDP Expedition 364

NASA Astrophysics Data System (ADS)

Christeson, G. L.; Gebhardt, C.; Gulick, S. P. S.; Le Ber, E.; Lofi, J.; Morgan, J. V.; Nixon, C.; Rae, A.; Schmitt, D. R.

2017-12-01

IODP/ICDP Expedition 364 Hole M0077A drilled into the peak ring of the Chicxulub impact crater, recovering core between 505.7 and 1334.7 m below the seafloor (mbsf). Physical property measurements include wireline logging data, a vertical seismic profile (VSP), Multi-Sensor Core Logger (MSCL) measurements, and discrete sample measurements. The Hole M0077A peak ring rocks have unusual physical properties. Across the boundary between post-impact sediment and crater breccia we measure a sharp decrease in velocities and densities, and an increase in porosity. Mean crater breccia values are 3000-3300 m/s, 2.14-2.15 g/cm3, and 31% for velocity, density, and porosity, respectively. This zone is also associated with a low-frequency reflector package on MCS profiles and a low-velocity layer in FWI images, both confirmed from the VSP dataset. The thin (24 m) crater melt unit has mean velocity measurements of 3800-4150 m/s, density measurements of 2.32-2.34 g/cm3, and porosity measurements of 20%; density and porosity values are intermediate between the overlying impact breccia and underlying granitic basement, while the velocity values are similar to those for the underlying basement. The Hole M0077A crater melt unit velocities and densities are considerably less than values of 5800 m/s and 2.68 g/cm3 measured at an onshore well located in the annular trough. The uplifted granitic peak ring materials have mean values of 4100-4200 m/s, 2.39-2.44 g/cm3, and 11% for compressional wave velocity, density, and porosity, respectively; these values differ significantly from typical granite which has higher velocities (5400-6000 m/s) and densities (2.62-2.67 g/cm3), and lower porosities (<1%). All Hole M0077A peak-ring velocity, density, and porosity measurements indicate considerable fracturing, and are consistent with numerical models for peak-ring formation.

Glacial-Interglacial, Orbital and Millennial-Scale Climate Variability for the Last Glacial Cycle at Shackleton Site U1385 based on Dinoflagellate Cysts

NASA Astrophysics Data System (ADS)

Datema, M.

2015-12-01

The Shackleton Site (IODP Expedition 339 Site U1385), located off the West-Portuguese Margin, preserves a continuous high-fidelity record of millennial-scale climate variability for the last several glacial cycles (~1.4 Myr) that can be correlated precisely to patterns observed in polar ice cores. In addition, rapid delivery of terrestrial material to the deep-sea environment allows the correlation of these marine records to European terrestrial climate records. This unique marine-ice-terrestrial linkage makes the Shackleton Site the ideal reference section for studying Quaternary abrupt climate change. The main objective of studying Site U1385 is to establish a marine reference section of Pleistocene climate change. We generated (sub)millennial-scale (~600 year interval) dinoflagellate cyst (dinocyst) assemblage records from Shackleton Site U1385 (IODP Expedition 339) to reconstruct sea surface temperature (SST) and productivity/upwelling over the last 152 kyrs. In addition, our approach allows for detailed land-sea correlations, because we also counted assemblages of pollen and spores from higher plants. Dinocyst SST and upwelling proxies, as well as warm/cold pollen proxies from Site U1385 show glacial-interglacial, orbital and stadial-interstadial climate variability and correlate very well to Uk'37, planktic foraminifer δ18O and Ca/Ti proxies of previously drilled Shackleton Sites and Greenland Ice Core δ18O. The palynological proxies capture (almost) all Dansgaard-Oeschger events of the last glacial cycle, also before ~70 ka, where millennial-scale variability is overprinted by precession. We compare the performance and results of the palynology of Site U1385 to proxies of previously drilled Shackleton Sites and conclude that palynology strengthens the potential of this site to form a multi-proxy reference section for millennial scale climate variability across the Pleistocene-Holocene. Finally, we will present a long-term paleoceanographic perspective down to ~150 ka.

The oldest Quaternary ooids and young reefs in the eastern Indian Ocean, evidence from the Northwest Shelf of Australia, IODP Expedition 356.

NASA Astrophysics Data System (ADS)

Gallagher, S. J.; Reuning, L.; Himmler, T.; Henderiks, J.; De Vleeschouwer, D.; Groeneveld, J.; Fulthorpe, C.; Bogus, K.; Expedition 356 Scientists, I.

2016-12-01

Modern reefs are common in the Indian Ocean off the west coast of Australia (south of 15°S) where the warm Leeuwin Current extends their modern distribution to 29°S. Two key features that distinguish these tropical from non-tropical carbonates are the presence of coral reefs and ooids. Coral reefs are generally confined to seawater >18°C. Ooids form at temperatures >20°C with salinities >37‰. Modern ooids are forming in the hypersaline Shark Bay and are well known from late Quaternary strata in the region. Globally, marine ooids have been interpreted to be direct evidence of physiochemical precipitation from seawater during periods of elevated alkalinity and supersaturation. Their occurrence in the subsurface of the Northwest Shelf of Australia (NWS) may be used as sea surface temperature, palaeobathymetry and aridity indices. However, the longer-term history of reefs and ooids is not well constrained in the NWS. IODP expedition 356 cored a series of sections down dip from the Houtman-Abrolhos (29°S) and Barrow Island reefs (22°S) and up dip from the Rowley Shoals (18°S) to determine their age and origin. The stratigraphy of the cored sections was mapped using regional seismic data to constrain the age of reef onset. Coring also yielded several horizons of pre-late Quaternary ooids. Our analyses reveals that reefs from 22°S to 30°S are younger than 600,000 years old and that ooids are present in strata up to 750,000 years old. We suggest stronger Leeuwin Current activity related to an enhanced Indonesian Throughflow and increased aridity triggered tropical carbonate expansion on the Northwest Shelf during the Middle Pleistocene Transition. Knowledge of the timing and circumstances that triggered tropical reef development in the Indo-Pacific in the past is critical if we are to understand the resilience of modern reefs with future climate change.

Provenance of Marine Sediment in the Gulf of Alaska, IODP Expedition 341: Links Between Sediment Derivation, Glacial Systems, and Exhumation of the Coastal Mountain Belts

NASA Astrophysics Data System (ADS)

Allen, W. K.; Dunn, C. A.; Enkelmann, E.; Ridgway, K.; Colliver, L.

2015-12-01

Provenance analysis of Neogene sand and diamict beds from marine boreholes drilled by the IODP Expedition 341 provides a marine sedimentary record of the interactions between tectonics, climate and sediment deposition along a glaciated convergent margin. The 341 boreholes represent a cross-margin transect that sampled the continental shelf, slope, and deep sea Surveyor Fan of the Gulf of Alaska. Our dataset currently consists of ~ 650 detrital zircons selected for double dating method utilizing both detrital zircon fission track (FT) and U-Pb analysis from sand and diamict beds, as well as zircon U-Pb geochronology and apatite FT from igneous and gneissic clasts. Detrital zircon U-Pb geochronology of sand records dominant peak ages of 53, 62, 70, and 98 Ma with minor populations of 117, 154, and 170 Ma. Most of these ages can be correlated to primary igneous sources in the Coast Plutonic Complex, the Chugach Metamorphic Complex, the plutonic rocks of Wrangellia, and the Sanak-Baranoff plutonic belt. All samples analyzed to date, covering a 10 Myr range, share nearly identical detrital zircon populations suggesting similar primary sediment sources and reworking of sediment in thrust belts and accretionary prisms along this convergent margin. Plutonic and gneissic clasts collected from the boreholes on the shelf have already been double dated. These clasts have general U-Pb zircon crystallization ages of 52-54 Ma and apatite fission track cooling ages of 10-12 Ma. These results, along with previous published studies, indicate that these clasts were derived from the Chugach Metamorphic Complex and were eroded and transported by the Bagley Ice Field and Bering Glacier. Future results using this approach should allow us to pinpoint which parts of the exhumed onshore ranges and which glacial systems provided sediment to marine environments in the Gulf of Alaska.

Developing a High-Resolution Paleointensity Assisted Chronology Through the Matuyama-Brunhes Transitional Interval (0.7 to 1.25 Ma) for the NE Pacific From IODP Expedition 341, Sites U1417 and U1418

NASA Astrophysics Data System (ADS)

Stoner, J. S.; Morey, A. E.; Mix, A. C.; Velle, J. H.; St-Onge, G.; Ge, S.; Asahi, H.

2016-12-01

Our understanding of the geomagnetic field and its application as a stratigraphic dating method are fundamentally limited by a lack of high quality records from many regions of the globe. The NE Pacific is one such region, not only lacking in quality paleomagnetic records, but as a region that is difficult to date using traditional Quaternary marine sediment methods, that would greatly benefit from detailed magnetic stratigraphies. We present u-channel and shipboard paleomagnetic data focusing on Matuyama-Brunhes transitional interval ( 0.7 to 1.25 Ma) from two IODP Sites (U1417 and U1418) drilled during Expedition 341 (South Alaska). Progressive AF demagnetization of u-channel samples, constrained by hysteresis data in the 100 to 200 m (CCSF-a) interval of Site U1417 define a well resolved, low coercivity, magnetization consistent with geocentric axial dipole expectations that improves upon reliable shipboard directions and intensities. Although ultrahigh resolution (>1 m /kyr) Site U1418 could not be u-channeled through the 400 to 900 m (CSF-a) rotary cored interval, correlations between u-channel data at Site U1417 and shipboard data at Site U1418 are robust enough to allow transference of its substantially more complete oxygen isotopic record to Site U1417. Passing all criteria for reliability, normalized remanence at Site U1417 using both ARM acquisition and ARM demagnetization, provides a relative paleointensity proxy that can be correlated with well-dated paleointensity stacks. This comparison allows an initial paleointensity assisted chronology to be developed; facilitating evaluation of both regional climate records through the middle Pleistocene transition, and the paleo-geomagnetic record that preserves polarity transitions, excursions, intensity variations, and secular variation during both polarities.

Take One Boat: from offshore science to onshore art

NASA Astrophysics Data System (ADS)

Cotterill, C.

2017-12-01

The International Ocean Discovery Program (IODP) is a collaborative programme that works to explore the oceans and the rocks beneath them. Working from shallow to deep waters, and in ice covered to more tropical areas, scientists work together to sample ocean sediments and rocks, and install subsea observatories, in order to investigate our planets dynamic history. The European Consortium for Ocean Research Drilling (ECORD) are one arm of IODP, and the Education and Outreach Task Force are investigating ways of taking education and outreach further - how can we convey the excitement of this program to others and inspire careers in STEM subjects?Cape Farewell are a think / do tank who gather artists, designers, filmmakers and writers to interact with scientists and find ways to address climate change. From creation of internationally touring artworks to films and novels, Cape Farewell continues to educate engage and inspire. For 3 years the author was involved in Cape Farewell not only as a research scientist, but also as a mentor within the educational programme. Over the course of two expeditions, students were invited to design both a science research project and an accompanying arts project that investigated climate change in this fragile environment, replicating the model used for professional scientists and artists. The long term aim of the project was to support peer to peer learning, with students working as youth ambassadors within their schools and communities. With outputs from this style of engagement now including digital artwork exhibitions, a multi-disciplinary arts school, online resources and the initiation of the youth climate change summit, this talk investigates what lessons can be learnt from this dynamic combination of arts and science, to develop a programme that takes just one boat, and makes a big change in how we communicate science. "The art the students have been producing has been inspired by the science they have learnt, what they experienced during the voyage and their own narratives of being in the Arctic. Unlike school, boundaries between subjects have not been important. Their learning was experiential and in many cases the voyage was a life changing experience" Subathra Subramaniam, Choreographer and science teacher

First evidence of denitrification vis-à-vis monsoon in the Arabian Sea since Late Miocene.

PubMed

Tripathi, Shubham; Tiwari, Manish; Lee, Jongmin; Khim, Boo-Keun

2017-02-21

In the Arabian Sea, South Asian monsoon (SAM)-induced high surface water productivity coupled with poor ventilation of intermediate water results in strong denitrification within the oxygen minimum zone (OMZ). Despite the significance of denitrification in the Arabian Sea, we have no long-term record of its evolution spanning the past several million years. Here, we present the first record of denitrification evolution since Late Miocene (~10.2 Ma) in the Eastern Arabian Sea, where the SAM generates moderate surface water productivity, based on the samples retrieved during the International Ocean Discovery Program (IODP) Expedition 355. We find that (i) the SAM was persistently weaker from ~10.2 to 3.1 Ma; it did not intensify at ~8 Ma in contrast to a few previous studies, (ii) on tectonic timescale, both the SAM and the East Asian Monsoon (EAM) varied synchronously, (iii) the first evidence of denitrification and productivity/SAM intensification was at ~3.2-2.8 Ma that coincided with Mid-Pliocene Warm Period (MPWP), and (iv) the modern strength of the OMZ where denitrification is a permanent feature was attained at ~1.0 Ma.

First evidence of denitrification vis-à-vis monsoon in the Arabian Sea since Late Miocene

NASA Astrophysics Data System (ADS)

Tripathi, Shubham; Tiwari, Manish; Lee, Jongmin; Khim, Boo-Keun; Pandey, Dhananjai K.; Clift, Peter D.; Kulhanek, Denise K.; Andò, Sergio; Bendle, James A. P.; Aharonovich, Sophia; Griffith, Elizabeth M.; Gurumurthy, Gundiga P.; Hahn, Annette; Iwai, Masao; Kumar, Anil; Kumar, A. Ganesh; Liddy, Hannah M.; Lu, Huayu; Lyle, Mitchell W.; Mishra, Ravi; Radhakrishna, Tallavajhala; Routledge, Claire M.; Saraswat, Rajeev; Saxena, Rakesh; Scardia, Giancarlo; Sharma, Girish K.; Singh, Arun D.; Steinke, Stephan; Suzuki, Kenta; Tauxe, Lisa; Xu, Zhaokai; Yu, Zhaojie

2017-02-01

In the Arabian Sea, South Asian monsoon (SAM)-induced high surface water productivity coupled with poor ventilation of intermediate water results in strong denitrification within the oxygen minimum zone (OMZ). Despite the significance of denitrification in the Arabian Sea, we have no long-term record of its evolution spanning the past several million years. Here, we present the first record of denitrification evolution since Late Miocene (~10.2 Ma) in the Eastern Arabian Sea, where the SAM generates moderate surface water productivity, based on the samples retrieved during the International Ocean Discovery Program (IODP) Expedition 355. We find that (i) the SAM was persistently weaker from ~10.2 to 3.1 Ma it did not intensify at ~8 Ma in contrast to a few previous studies, (ii) on tectonic timescale, both the SAM and the East Asian Monsoon (EAM) varied synchronously, (iii) the first evidence of denitrification and productivity/SAM intensification was at ~3.2-2.8 Ma that coincided with Mid-Pliocene Warm Period (MPWP), and (iv) the modern strength of the OMZ where denitrification is a permanent feature was attained at ~1.0 Ma.

Understanding Himalayan erosion and the significance of the Nicobar Fan

NASA Astrophysics Data System (ADS)

McNeill, Lisa C.; Dugan, Brandon; Backman, Jan; Pickering, Kevin T.; Pouderoux, Hugo F. A.; Henstock, Timothy J.; Petronotis, Katerina E.; Carter, Andrew; Chemale, Farid; Milliken, Kitty L.; Kutterolf, Steffen; Mukoyoshi, Hideki; Chen, Wenhuang; Kachovich, Sarah; Mitchison, Freya L.; Bourlange, Sylvain; Colson, Tobias A.; Frederik, Marina C. G.; Guèrin, Gilles; Hamahashi, Mari; House, Brian M.; Hüpers, Andre; Jeppson, Tamara N.; Kenigsberg, Abby R.; Kuranaga, Mebae; Nair, Nisha; Owari, Satoko; Shan, Yehua; Song, Insun; Torres, Marta E.; Vannucchi, Paola; Vrolijk, Peter J.; Yang, Tao; Zhao, Xixi; Thomas, Ellen

2017-10-01

A holistic view of the Bengal-Nicobar Fan system requires sampling the full sedimentary section of the Nicobar Fan, which was achieved for the first time by International Ocean Discovery Program (IODP) Expedition 362 west of North Sumatra. We identified a distinct rise in sediment accumulation rate (SAR) beginning ∼9.5 Ma and reaching 250-350 m/Myr in the 9.5-2 Ma interval, which equal or far exceed rates on the Bengal Fan at similar latitudes. This marked rise in SAR and a constant Himalayan-derived provenance necessitates a major restructuring of sediment routing in the Bengal-Nicobar submarine fan. This coincides with the inversion of the Eastern Himalayan Shillong Plateau and encroachment of the west-propagating Indo-Burmese wedge, which reduced continental accommodation space and increased sediment supply directly to the fan. Our results challenge a commonly held view that changes in sediment flux seen in the Bengal-Nicobar submarine fan were caused by discrete tectonic or climatic events acting on the Himalayan-Tibetan Plateau. Instead, an interplay of tectonic and climatic processes caused the fan system to develop by punctuated changes rather than gradual progradation.

Middle Miocene environmental and climatic evolution at the Wilkes Land margin, East Antarctica

NASA Astrophysics Data System (ADS)

Sangiorgi, Francesca; Bijl, Peter; Passchier, Sandra; Salzmann, Ulrich; Schouten, Stefan; Pross, Jörg; Escutia, Carlota; Brinkhuis, Henk

2015-04-01

Integrated Ocean Drilling Program (IODP) Expedition 318 successfully drilled a Middle Miocene (~ 17 - 12.5 Ma) record from the Wilkes Land Margin at Site U1356A (63°18.6138'S, 135°59.9376'E), located at the transition between the continental rise and the abyssal plain at 4003 mbsl. We present a multiproxy palynological (dinoflagellate cyst, pollen and spores), sedimentological and organic geochemical (TEX86, MBT/CBT) study, which unravels the environmental and climate variability across the Miocene Climatic Optimum (MCO, ~17-15 Ma) and the Mid Miocene Climate Transition (MMCT). Several independent lines of evidence suggest a relatively warm climate during the MCO. Dinocyst and pollen assemblage diversity at the MCO is unprecedented for a Neogene Antarctic record and indicates a temperate, sea ice-free marine environment, with woody sub-antarctic vegetation with elements of forest/shrub tundra and peat lands along the coast. These results are further confirmed by relatively warm TEX86-derived Sea Surface Temperatures and mild MBT-derived continental temperatures, and by the absence of glacially derived deposits and very few ice-rafted clasts. A generally colder but highly dynamic environment is suggested for the interval 15-12.5 Ma.

Facies and Depositional History of Arc-Related, Deep-Marine Volcaniclastic Rocks in Core Recovered on International Ocean Discovery Program Expedition 351, Philippine Sea

NASA Astrophysics Data System (ADS)

Johnson, K. E.; Waldman, R.; Marsaglia, K. M.

2016-12-01

The Izu-Bonin-Mariana (IBM) Arc System, south of Japan, hosts a multitude of active and extinct (remnant) volcanic arcs and associated basins partly filled with volcanic sediment. Core extracted adjacent to the proto-IBM arc (Kyushu-Palau Ridge; KPR), in the Amami-Sankaku Basin (ASB) during International Ocean Discovery Program (IODP) Expedition 351, contains an incredibly well-preserved record of backarc sedimentation resulting from changing tectonic regimes during arc development and decline. Approximately 1000 meters of Eocene to Oligocene volcaniclastic sedimentary rocks were analyzed via shipboard core photos, core descriptions, and thin sections with the intention of understanding the depositional history at this site. A database of stratigraphic columns, 539 section and 147 core summaries, was created to display grain size trends, sedimentary structures, bedding characteristics, and facies changes. Individual depositional events were classified using existing and slightly modified classification schemes for muddy, sandy, and gravel-rich gravity flow deposits, as well as muddy deposits and tuffs. Downhole trends show repeating coarsening-upward intervals that grade from fine-grained turbidites to coarser turbidites and debrites. These trends indicate how the active depositional systems evolved upsection as the arc matured. Following arc initiation, facies deposited were primarily mud-rich; these coarsened-upward into 12 stacked sequences of submarine lobe and channel facies with sediment from one or more volcanic sources. These are interpreted to represent the building of the arc edifice that began 41 Ma. Four distinct periods of coarse lobe accumulation created a thick submarine fan over a period of nearly 13 million years. An abrupt shift to muddy turbidites at 30 Ma represents the onset of rifting of the paleo-IBM arc as backarc spreading in the Shikoku Basin was initiated and volcaniclastic supply to the ASB waned with formation of the KPR remnant arc.

High-resolution and high-precision correlation of dark and light layers in the Quaternary hemipelagic sediments of the Japan Sea recovered during IODP Expedition 346

NASA Astrophysics Data System (ADS)

Tada, Ryuji; Irino, Tomohisa; Ikehara, Ken; Karasuda, Akinori; Sugisaki, Saiko; Xuan, Chuang; Sagawa, Takuya; Itaki, Takuya; Kubota, Yoshimi; Lu, Song; Seki, Arisa; Murray, Richard W.; Alvarez-Zarikian, Carlos; Anderson, William T.; Bassetti, Maria-Angela; Brace, Bobbi J.; Clemens, Steven C.; da Costa Gurgel, Marcio H.; Dickens, Gerald R.; Dunlea, Ann G.; Gallagher, Stephen J.; Giosan, Liviu; Henderson, Andrew C. G.; Holbourn, Ann E.; Kinsley, Christopher W.; Lee, Gwang Soo; Lee, Kyung Eun; Lofi, Johanna; Lopes, Christina I. C. D.; Saavedra-Pellitero, Mariem; Peterson, Larry C.; Singh, Raj K.; Toucanne, Samuel; Wan, Shiming; Zheng, Hongbo; Ziegler, Martin

2018-12-01

The Quaternary hemipelagic sediments of the Japan Sea are characterized by centimeter- to decimeter-scale alternation of dark and light clay to silty clay, which are bio-siliceous and/or bio-calcareous to a various degree. Each of the dark and light layers are considered as deposited synchronously throughout the deeper (> 500 m) part of the sea. However, attempts for correlation and age estimation of individual layers are limited to the upper few tens of meters. In addition, the exact timing of the depositional onset of these dark and light layers and its synchronicity throughout the deeper part of the sea have not been explored previously, although the onset timing was roughly estimated as 1.5 Ma based on the result of Ocean Drilling Program legs 127/128. Consequently, it is not certain exactly when their deposition started, whether deposition of dark and light layers was synchronous and whether they are correlatable also in the earlier part of their depositional history. The Quaternary hemipelagic sediments of the Japan Sea were drilled at seven sites during Integrated Ocean Drilling Program Expedition 346 in 2013. Alternation of dark and light layers was recovered at six sites whose water depths are > 900 m, and continuous composite columns were constructed at each site. Here, we report our effort to correlate individual dark layers and estimate their ages based on a newly constructed age model at Site U1424 using the best available paleomagnetic datum and marker tephras. The age model is further tuned to LR04 δ18O curve using gamma ray attenuation density (GRA) since it reflects diatom contents that are higher during interglacial high-stands. The constructed age model for Site U1424 is projected to other sites using correlation of dark layers to form a high-resolution and high-precision paleo-observatory network that allows to reconstruct changes in material fluxes with high spatio-temporal resolutions.

Australian Northwest Shelf: a Late Neogene Reversible Tectonic Event

NASA Astrophysics Data System (ADS)

Kominz, M. A.; Gurnis, M.; Gallagher, S. J.; Expedition 356 Scientists, I.

2017-12-01

The Northwest Shelf (NWS) of Australia is characterized by several offshore basins with active rifting in Permian and Jurassic time. Thus, by the Late Neogene this continental margin should be a very slowly subsiding passive margin. However, thick, poorly dated sediments have been noted in this region leading to speculation that this part of Australia has undergone down-warping in this time period. The International Ocean Discovery Program (IODP) Expedition 356 was designed, in part, to better constrain this even in both time and space. Post-cruise Airy-backstripping analyses of samples from four IODP 356 well sites, located as far south as the Perth Basin and as far North as the Carnarvon Basin, suggest that, in fact, this region has undergone a latest Miocene (≈ 8 to 6 Ma) subsidence event followed by a later (≈ 2 to 1 Ma) uplift event. Age constraints are from micropaleontology with some refinement using climate cycle-stratigraphy. Water depth constraints are from benthic foraminifera and from quantitative ratios of benthic foraminifera to planktonic foraminifera. These event cannot be explained as related to either the high-magnitude glacial eustatic changes nor can the uplift event be eliminated and ascribed to sediments filling the accommodation space generated in the earlier event. The magnitude and duration of the vertical movements are remarkably similar and suggests that the subsidence is reversible. Reversibility is a key aspect of a dynamic topography signal. However, it is difficult to produce a mantle anomaly that reproduces the subsidence and subsequent uplift with the requisite amplitude and rates as observed in the NWS of Australia. Additionally, the subduction of the Australian Plate into the Java Trench is too distant to affect this region of Australia. Modeling of a flexural warping due to in-plane stress related to collision of Timor with the Java trench is

Climate Variability and Siliciclastic Deposition on a Carbonate Margin - Neogene of the Northwest Shelf of Australia

NASA Astrophysics Data System (ADS)

Tagliaro, G.; Fulthorpe, C.; Gallagher, S. J.; McHugh, C.; Kominz, M. A.; Lavier, L.

2017-12-01

The Bare Formation represents a unique episode of Neogene siliciclastic deposition on the carbonate-dominated Australian Northwest Shelf (NWS). International Ocean Discovery Program (IODP) Expedition 356 drilling results, coupled with interpretation of 3D seismic data, allow us to constrain the timing of siliciclastic deposition and the associated sedimentary processes. IODP Sites U1462, U1463 and U1464 provide age control that reveals the relationship of the Bare Fm. to the adjacent carbonate sediments. The Bare Fm. is preceded by middle to late Miocene shelf exposure and karstification. Elongate beach barrier deposits with small lobate deltas to the NE developed during the late Miocene. However, fluvial deposition increased markedly in the Zanclean, resulting in development of a large tide-and-wave-influenced delta, with evidence of tidal channels, comprising the thickest component of the Bare Fm. Siliciclastic input decreased in the Piacenzian, leading to margin retreat and final termination near the Plio-Pleistocene boundary. The results correlate with regional climate and sedimentary records derived from Sites U1459, U1463 and U1464, that indicate an arid middle to late Miocene, followed by a humid interval in the Zanclean and a return to arid conditions during the Piacenzian. Therefore, we suggest that fluctuation of surface runoff patterns in the continental hinterlands is the primary control of Bare Fm. evolution. Hence, Neogene siliciclastic distribution is a result of regional climate variability on the NWS. Up to 40 km of shoreline advance is verified in the Late Miocene and Pliocene, an example of climate-driven modification of a continental margin. Additionally, longshore transport intensifies during the Pliocene humid interval, causing NE migration of the deltaic system. Sedimentary and climate transitions are linked to reorganization of Indian Ocean paleoceanography, accompanying northward migration of the Australian continent and progressive restriction of the Indonesian Throughflow.

Chronology of Late Quaternary Glacial Cycles in the Bering Trough, Gulf of Alaska: Constraints from Core-Log-Seismic Integration across the Continental Shelf and Slope

NASA Astrophysics Data System (ADS)

Clary, W. A.; Worthington, L. L.; Daigle, H.; Slagle, A. L.; Gulick, S. P. S.

2016-12-01

Sediments offshore Southern Alaska offer a natural laboratory to study glacial erosion, sediment deposition, and orogenesis. A major goal of Integrated Ocean Drilling Program (IODP) Expedition 341 was investigation of interrelationships among tectonic processes, paleoclimate, and glacial activity. Here, we focus on core-log-seismic integration of IODP Sites U1420 and U1421 on the shallow shelf and slope near the Bering Trough, a glacially derived shelf-crossing landform. These sites sample glacial and marine sediments that record a history of sedimentation following the onset of glacial intensification near the mid-Pleistocene transition (1.2 Ma) and Yakutat microplate convergence with North America. Ocean drilling provides important stratigraphic, physical properties, and age data in depth which support development of a stratigraphic model that can be extended across the shelf if carefully calibrated to local and regional seismic surveys. We use high resolution multichannel seismic, core, and logging data to develop a time-depth relationship (TDR) and update the developing chronostratigraphic model based on correlation of seismic sequence boundaries and drilling-related data, including biostratigraphic and paleomagnetic age controls. We calibrate, combine, and interpolate core and logging data at each site to minimize gaps in physical property information and generate synthetic seismic traces. At Site U1421, vertical seismic profiling further constrains the TDR, and provides input for the initial velocity model during the tie. Finally, we match reflectors in the synthetic trace with events in nearby seismic reflection data to establish a TDR at each site. We can use this relationship to better interpret the development of the Bering Trough, a recurring and favored path for ice streams and glacial advance. Initial results suggest late Pleistocene sedimentation rates of at least 1 km/m.y. on average, and variable sedimentation rates which are possibly correlated with paleoenvironmental indicators such as sea ice related species of diatoms.

3D Porosity Estimation of the Nankai Trough Sediments from Core-log-seismic Integration

NASA Astrophysics Data System (ADS)

Park, J. O.

2015-12-01

The Nankai Trough off southwest Japan is one of the best subduction-zone to study megathrust earthquake fault. Historic, great megathrust earthquakes with a recurrence interval of 100-200 yr have generated strong motion and large tsunamis along the Nankai Trough subduction zone. At the Nankai Trough margin, the Philippine Sea Plate (PSP) is being subducted beneath the Eurasian Plate to the northwest at a convergence rate ~4 cm/yr. The Shikoku Basin, the northern part of the PSP, is estimated to have opened between 25 and 15 Ma by backarc spreading of the Izu-Bonin arc. The >100-km-wide Nankai accretionary wedge, which has developed landward of the trench since the Miocene, mainly consists of offscraped and underplated materials from the trough-fill turbidites and the Shikoku Basin hemipelagic sediments. Particularly, physical properties of the incoming hemipelagic sediments may be critical for seismogenic behavior of the megathrust fault. We have carried out core-log-seismic integration (CLSI) to estimate 3D acoustic impedance and porosity for the incoming sediments in the Nankai Trough. For the CLSI, we used 3D seismic reflection data, P-wave velocity and density data obtained during IODP (Integrated Ocean Drilling Program) Expeditions 322 and 333. We computed acoustic impedance depth profiles for the IODP drilling sites from P-wave velocity and density data. We constructed seismic convolution models with the acoustic impedance profiles and a source wavelet which is extracted from the seismic data, adjusting the seismic models to observed seismic traces with inversion method. As a result, we obtained 3D acoustic impedance volume and then converted it to 3D porosity volume. In general, the 3D porosities show decrease with depth. We found a porosity anomaly zone with alteration of high and low porosities seaward of the trough axis. In this talk, we will show detailed 3D porosity of the incoming sediments, and present implications of the porosity anomaly zone for the megathrust fault behavior.

Chemical and isotopic signature of bulk organic matter and hydrocarbon biomarkers within mid-slope accretionary sediments of the northern Cascadia margin gas hydrate system

USGS Publications Warehouse

Kaneko, Masanori; Shingai, Hiroshi; Pohlman, John W.; Naraoka, Hiroshi

2010-01-01

The chemical and isotopic compositions of sedimentary organic matter (SOM) from two mid-slope sites of the northern Cascadia margin were investigated during Integrated Ocean Drilling Program (IODP) Expedition 311 to elucidate the organic matter origins and identify potential microbial contributions to SOM. Gas hydrate is present at both locations (IODP Sites U1327 and U1328), with distinct patterns of near-seafloor structural accumulations at the cold seep Site U1328 and deeper stratigraphic accumulations at the slope-basin Site U1327. Source characterization and evidence that some components of the organic matter have been diagenetically altered are determined from the concentrations and isotopic compositions of hydrocarbon biomarkers, total organic carbon (TOC), total nitrogen (TN) and total sulfur (TS). The carbon isotopic compositions of TOC (δ13CTOC = −26 to −22‰) and long-chain n-alkanes (C27, C29 and C31, δ13C = −34 to − 29‰) suggest the organic matter at both sites is a mixture of 1) terrestrial plants that employ the C3 photosynthetic pathway and 2) marine algae. In contrast, the δ15NTN values of the bulk sediment (+ 4 to + 8‰) are consistent with a predominantly marine source, but these values most likely have been modified during microbial organic matter degradation. The δ13C values of archaeal biomarker pentamethylicosane (PMI) (− 46.4‰) and bacterial-sourced hopenes, diploptene and hop-21-ene (− 40.9 to − 34.7‰) indicate a partial contribution from methane carbon or a chemoautotrophic pathway. Our multi-isotope and biomarker-based conclusions are consistent with previous studies, based only on the elemental composition of bulk sediments, that suggested a mixed marine-terrestrial organic matter origin for these mid-slope sites of the northern Cascadia margin.

One Year of Data of Scimpi Borehole Measurements

NASA Astrophysics Data System (ADS)

Insua, T. L.; Moran, K.; Kulin, I.; Farrington, S.; Newman, J. B.; Riedel, M.; Scherwath, M.; Heesemann, M.; Pirenne, B.; Iturrino, G. J.; Masterson, W.; Furman, C.

2014-12-01

The Simple Cabled Instrument for Measuring Parameters In-Situ (SCIMPI) is a new subseafloor observatory designed to study dynamic processes in the subseabed using a simple and low-cost approach compared to a Circulation Obviation Retrofit Kit (CORK). SCIMPI was successfully installed at the Integrated Ocean Drilling Program (IODP) Site U1416 during IODP Expedition 341S in May 2013. SCIMPI is designed to measure pore pressure, temperature and electrical resistivity over time in a borehole. The first SCIMPI prototype comprises nine modules joined in a single array by flexible cables. Multiple floats keep the system taut against a sinker bar weight located on SCIMPI and resting on the bottom of the borehole. All the modules record temperature and electrical resistivity, and three are also equipped with pressure sensors. Currently, SCIMPI operates as an autonomous instrument with a data logger that is recovered using an ROV. The second recovery of the SCIMPI data logger took place during the Ocean Networks Canada maintenance cruise, Wiring the Abyss 2014, on May 25th, 2014. The pressure sensor data show a stable trend in which tidal effects are observed in through the one year deployment. The temperature measurements in all the modules became stable over time with smaller variations over the last several months. The only temperature sensor differing from this trend is the shallowest, located at 8 meters below seafloor. This module shows a sudden spike of ~20°C that on April 5th, 2014, an event that was repeated several times from April 25th until recovery of modules. The electrical resistivity sensors show variations over time that could be related to gas hydrate dynamics at the Site. Interpretation of these data is speculative at this time but borehole-sealing processes as well as the formation of gas hydrate are potential processes influencing the recordings. SCIMPI will soon be connected to Ocean Networks Canada's NEPTUNE observatory at Clayoquot Slope node to provide real-time data from this subseafloor observatory.

Advancing Understanding of Earthquakes by Drilling an Eroding Convergent Margin

NASA Astrophysics Data System (ADS)

von Huene, R.; Vannucchi, P.; Ranero, C. R.

2010-12-01

A program of IODP with great societal relevance is sampling and instrumenting the seismogenic zone. The zone generates great earthquakes that trigger tsunamis, and submarine slides thereby endangering coastal communities containing over sixty percent of the earth’s population. To asses and mitigate this endangerment it is urgent to advance understanding of fault dynamics that allows more timely anticipation of hazardous seismicity. Seismogenesis on accreting and eroding convergent plate boundaries apparently differ because of dissimilar materials along the interplate fault. As the history of instrumentally recorded earthquakes expands the difference becomes clearer. The more homogeneous clay, silt and sand subducted at accreting margins is associated with great earthquakes (M 9) whereas the fragmented upper plate rock that can dominate subducted material along an eroding margin plate interface is associated with many tsunamigenic earthquakes (Bilek, 2010). Few areas have been identified where the seismogenic zone can be reached with scientific drilling. In IODP accreting margins are studied on the NanTroSeize drill transect off Japan where the ultimate drilling of the seismogenic interface may occur by the end of IODP. The eroding Costa Rica margin will be studied in CRISP where a drill program will begin in 2011. The Costa Rican geophysical site survey will be complete with acquisition and processing of 3D seismic data in 2011 but the entire drilling will not be accomplished in IODP. It is appropriate that the accreting margin study be accomplished soon considering the indications of a pending great earthquake that will affect a country that has devoted enormous resources to IODP. However, understanding the erosional end-member is scientifically as important to an understanding of fault mechanics. Transoceanic tsunamis affect the entire Pacific rim where most subduction zones are eroding margins. The Costa Rican subduction zone is less complex operationally and perhaps geologically than the Nankai margin. The developing Central American countries do not have the resources to contribute to IODP but this should not deter acquiring the scientific insights proposed in CRISP considering the broader scientific benefits. Such benefits include the first sampling and instrumentation of an actively eroding plate interface and drilling near or into an earthquake asperity. Drilling an eroding margin should significantly advance understanding of subduction zone fault mechanisms and help improve assessment of future hazardous earthquakes and tsunamis.

Refinement of late-Early and Middle Miocene diatom biostratigraphy for the east coast of the United States

USGS Publications Warehouse

Barron, John A.; Browning, James; Sugarman, Peter; Miller, Kenneth G.

2013-01-01

Integrated Ocean Drilling Program (IODP) Expedition 313 continuously cored Lower to Middle Miocene sequences at three continental shelf sites off New Jersey, USA. The most seaward of these, Site M29, contains a well-preserved Early and Middle Miocene succession of planktonic diatoms that have been independently correlated with the geomagnetic polarity time scale derived in studies from the equatorial and North Pacific. Shallow water diatoms (species of Delphineis, Rhaphoneis, and Sceptroneis) dominate in onshore sequences in Maryland and Virginia, forming the basis for the East Coast Diatom Zones (ECDZ). Integrated study of both planktonic and shallow water diatoms in Hole M29A as well as in onshore sequences in Maryland (the Baltimore Gas and Electric Company well) and Delaware (the Ocean Drilling Program Bethany Beach corehole) allows the refinement of ECDZ zones into a high-resolution biochronology that can be successfully applied in both onshore and offshore regions of the East Coast of the United States. Strontium isotope stratigraphy supports the diatom biochronology, although for much of the Middle Miocene it suggests ages that are on average 0.4 m.y. older. The ECDZ zonal definitions are updated to include evolutionary events of Delphineis species, and regional occurrences of important planktonic diatom marker taxa are included. Updated taxonomy, reference to published figures, and photographic images are provided that will aid in the application of this diatom biostratigraphy.

A Two Million Year Equatorial Paleogeomagnetic and Relative Paleointensity Record from IODP Site U1489 in the West Pacific Warm Pool: Towards an Improved Tuning Target.

NASA Astrophysics Data System (ADS)

He, L.; Chen, L.; Wang, X.; Zhao, X.; Xi, X.; Chen, R.

2016-12-01

International Ocean Discovery Program (IODP) Expedition 363 drilled nine sites in the West Pacific Warm Pool in October-December 2016. IODP Site U1489 (02°07.19'N, 141°01.67'E, 3421 meters water depth) located on the Eauripik Rise was drilled to a depth of 270 meters below sea floor using the advanced piston corer. Shipboard data revealed the upper 112 meters composite depth (mcd) consist of clay-rich nanno fossil ooze and contain all twenty-two geomagnetic reversals over the last 5 million years (Myrs). Shipboard generated rock magnetic data and post-cruise hysteresis data suggest the paleomagnetic record is carried by fine-grained pseudo-single domain magnetite. A shipboard estimate of relative paleointensity (RPI) was generated by normalizing the natural remanent magnetization (NRM) intensity after 15mT peak alternating field (AF) demagnetization of the shipboard half core measurement by whole round magnetic susceptibility (MS). Coherence of the NRM15mT/MS record with existing RPI stacks over the last 2 Myrs highlighted the potential for development of a RPI record back to the earliest Pliocene. Here we present the first u-channel measurements of the upper 40 mcd from Site U1489 spanning the last 2 Myrs. The NRM was measured at 1 cm intervals after stepwise AF demagnetization in peak fields of 15-100mT. Component inclination plots around that predicted by a geocentric axial dipole field and maximum angular deviation values are so far generally < 3° implying the paleomagnetic record is well resolved at Site U1489. Measurements of MS and anhysteretic remanent magnetization (ARM) characterize the environmental variability and provide a normalizer for the NRM to generate an estimate of RPI. The chronology is iteratively developed, initially based on polarity reversals boundaries, then by tuning MS to astronomical precession. We compare our RPI estimates to PISO-1500 and NARPI-2200 whose chronologies are based upon δ18O of benthic foraminifera to assess the appropriateness of orbital tuning and further constrain the U1489 chronology. Future plans include the measurement of the full 5 Myr sequence and integration of the RPI record with the benthic δ18O chronology over the same period to improve our understanding of the paleogeomagnetic record and provide a robust tuning target extending through the Pliocene.

Terrigenous provenance follows climate variability at IODP Site U1474, southwestern Indian Ocean

NASA Astrophysics Data System (ADS)

Babin, D. P.; Hemming, S. R.; Simon, M.; Hall, I. R.; Franzese, A. M.; Goldstein, S. L.; Cai, Y.; Liu, T.; Johns, M. A.; Tejada, L.; LeVay, L.

2017-12-01

International Ocean Discovery Program (IODP) Expedition 361 `South African Climates' sought records to document the role of the greater Agulhas Current system in global climate variability and southeast African hydroclimate over the past 5 Ma. IODP Site U1474 is located at the headwaters of the fully constituted Agulhas Current. Being close to the southeast African margin, the core location is ideally situated to track variations of terrigenous sediment delivery to the site, which may relate to climatic changes in southern Africa that follow variability in the Agulhas Current heat content. To analyze climate variability, we consider an XRF record for the site in combination with major and trace element chemistry and K-Ar ages from the clay fraction (<2um) plus bulk major element chemistry of 60 shipboard moisture and density samples spanning 4.8 Ma. These data are interpreted with a sea surface temperature (SST) record from Mg/Ca measurements spaced at 40 kyr on the surface dwelling (mixed layer) planktonic foraminifera Globigerinoides ruber. Both long-term trend and precessionally-paced changes in the terrigenous composition are evident. Fe/K ratios from XRF core scanning data are consistent with those previously reported (Simon et al. 2015 Sci. Reports) in a nearby core that spans the last 270 ka. Terrigenous mass accumulation rates are relatively constant at 3 g/cm3/ky from 5-2.5 Ma, then gradually decrease to 2 g/cm3/ky at the top. This declining flux is accompanied by older and more weathered and mafic sources, possibly a result of reduced precipitation in proximal catchments. It is suggested that the relationships between these proxies is explained by a greater relative contribution of sediment supplied from the Limpopo catchment compared to nearby drainage basins such as the Tugela. The SST record shows a cooling trend from the 27 °C average between 4.5-2.5 Ma to 25 °C at 1.0 Ma, followed by high amplitude changes (6 °C changes instead of °3 C) in SST in the 0-1.0 Ma interval, with minimum SST estimates of 21 °C. These changes are consistent with, but could lag behind models predicting aridification in Africa associated with a drop in Indian Ocean temperatures around 3-4 Ma, caused by tectonic changes in the Indonesian Throughflow that shifted its Pacific source waters further north (Cane & Molnar 2001 Science).

A Two Million Year Equatorial Paleogeomagnetic and Relative Paleointensity Record from IODP Site U1489 in the West Pacific Warm Pool: Towards an Improved Tuning Target.

NASA Astrophysics Data System (ADS)

Hatfield, R. G.; Stoner, J. S.; Kumagai, Y.

2017-12-01

International Ocean Discovery Program (IODP) Expedition 363 drilled nine sites in the West Pacific Warm Pool in October-December 2016. IODP Site U1489 (02°07.19'N, 141°01.67'E, 3421 meters water depth) located on the Eauripik Rise was drilled to a depth of 270 meters below sea floor using the advanced piston corer. Shipboard data revealed the upper 112 meters composite depth (mcd) consist of clay-rich nanno fossil ooze and contain all twenty-two geomagnetic reversals over the last 5 million years (Myrs). Shipboard generated rock magnetic data and post-cruise hysteresis data suggest the paleomagnetic record is carried by fine-grained pseudo-single domain magnetite. A shipboard estimate of relative paleointensity (RPI) was generated by normalizing the natural remanent magnetization (NRM) intensity after 15mT peak alternating field (AF) demagnetization of the shipboard half core measurement by whole round magnetic susceptibility (MS). Coherence of the NRM15mT/MS record with existing RPI stacks over the last 2 Myrs highlighted the potential for development of a RPI record back to the earliest Pliocene. Here we present the first u-channel measurements of the upper 40 mcd from Site U1489 spanning the last 2 Myrs. The NRM was measured at 1 cm intervals after stepwise AF demagnetization in peak fields of 15-100mT. Component inclination plots around that predicted by a geocentric axial dipole field and maximum angular deviation values are so far generally < 3° implying the paleomagnetic record is well resolved at Site U1489. Measurements of MS and anhysteretic remanent magnetization (ARM) characterize the environmental variability and provide a normalizer for the NRM to generate an estimate of RPI. The chronology is iteratively developed, initially based on polarity reversals boundaries, then by tuning MS to astronomical precession. We compare our RPI estimates to PISO-1500 and NARPI-2200 whose chronologies are based upon δ18O of benthic foraminifera to assess the appropriateness of orbital tuning and further constrain the U1489 chronology. Future plans include the measurement of the full 5 Myr sequence and integration of the RPI record with the benthic δ18O chronology over the same period to improve our understanding of the paleogeomagnetic record and provide a robust tuning target extending through the Pliocene.

Arabian Night and Sea Story - Biomarkers from a Giant Mass Transport Deposit.

NASA Astrophysics Data System (ADS)

Bratenkov, Sophia; Kulhanek, Denise K.; Clift, Peter D.; George, Simon C.

2016-04-01

The study of mass transport deposits (MTDs) is an important field of research due to the potential insights into catastrophic events in the past and modern geohazard threats (e.g. tsunamis). Submarine mass movements are very significant processes in sculpturing the structure of continental margins, particularly in their extent and magnitude that have consequences both in the modern day, as well as in the geological past. An understanding of the complex stratigraphy of a submarine mass transport deposit (MTD) might help in reconstructing the provenance and transport pathways of sedimentary material and thus give important insights into sedimentary dynamics and processes triggering specific events. Drilling operations during International Ocean Discovery Program (IODP) Expedition 355 Arabian Sea Monsoon, which took place during April and May, 2015 cored two sites in Laxmi Basin. Site U1456 was cored to 1109.4 m below seafloor (mbsf), with the oldest recovered rock dated to ~13.5-17.7 Ma. Site U1457 was cored to 1108.6 mbsf, with the oldest rock dated to ~62 Ma. At each site, we cored through ~330 m and ~190 m of MTD material. The MTD layers mainly consist of interbedded lithologies of dark grey claystone, light greenish calcarenite and calcilutite, and conglomerate/breccia, with ages based on calcareous nannofossil and foraminifer biostratigraphy ranging from the Eocene to early Miocene (Pandey et al., 2015). This MTD, known as Nataraja Slide, is the third largest MTD known from the geological record and the second largest on a passive margin. Calvés et al. (2015) identified a potential source area offshore Sourashstra on the Indian continental margin and invoked the single step mass movement model to explain the mechanism of emplacement. Initial shipboard work demonstrated the high variability in total organic carbon and total nitrogen levels in different layers within the MTD, which raises a number of questions related to the source and composition of the organic matter. Here we present the biomarker signature of the material based on gas chromatography-mass spectrometry (GC-MS) and high performance liquid chromatography-mass spectrometry (HPLC-MS) analyses. The purpose of this study is to understand the depositional and post-depositional processes of the sedimentary layers in the MTD. The unique opportunity of collaborative, multi-disciplinary data collection produced onboard the JOIDES Resolution, together with postcruise research, allows us to create a better understanding of the processes involved in creation of one of the largest known MTDs on Earth. References: Calvès, G., Huuse, M., Clift, P.D. and Brusset, S., 2015. Giant fossil mass wasting off the coast of West India: The Nataraja submarine slide. Earth and Planetary Science Letters, 432, pp.265-272. Pandey, D.K., Clift, P.D., Kulhanek, D.K., et al., 2015. Expedition 355 Preliminary Report: Arabian Sea Monsoon. International Ocean Discovery Program. http://dx.doi.org/10.14379/iodp.pr.355.2015

Elemental and Mineralogical Analysis of Silt Fraction from Site U1420, IODP Expedition 341

NASA Astrophysics Data System (ADS)

Salinas, J. K.; Jaeger, J. M.; Penkrot, M. L.

2016-12-01

In southeastern Alaska, the Chugach-St. Elias Mountains - the world's highest coastal mountain range - exhibit extreme topography due to the collision and subduction of the Yakutat microplate beneath the North American plate. The St. Elias orogen is younger than 30 Ma, with mountain building having occurred during a period of enhanced glacial erosion when erosive ice streams delivered sediment into the Gulf of Alaska. Integrated Ocean Drilling Program Expedition 341 set out to investigate the relationship between mountain building and glacial dynamics in the Gulf of Alaska. Sediment cores from site U1420 were collected, within the Bering trough, just offshore of the Bering Glacier. Analysis of Bering Trough seismic profiles demonstrates an evolution from tectonically-controlled to depositionally-controlled continental margin strata formation (Worthington et al., 2010). The goal of this study is to investigate the provenance of the silt-sized fraction (15-63 μm) of U1420 sediments across this transition in seismic facies using mineralogy and elemental geochemical analyses. XRD mineralogical analysis shows consistent downhole mineralogy with minor variations in relative peak intensities. Elemental ICP-MS geochemical analysis reveal concentrations of both major and trace elements to be very well constrained, with all major (Al, Ca, Fe, Mg, and Ti) and trace elemental data (Ce, Cr, Ga, La, Rb, Sc, Sr, Th, and Y) only varying downhole by few percent/ppm. Both the consistent downhole mineralogy and elemental data suggest that the provenance of the silt-sized sediment deposited offshore has not changed since initial deposition (<0.7 Ma). Comparison with onshore bedrock geochemistry and surface samples from the modern Gulf of Alaska indicate that U1420 silt is similar in composition to modern regional sediment sources and is a mixture of the different bedrock lithologies within the modern Bering Glacier drainage.

Effects of hydrothermal alteration on the magnetic mineralogy of mid-ocean ridge basalts, IODP Site 1301B, Juan de Fuca Ridge

NASA Astrophysics Data System (ADS)

Linville, L. M.; Housen, B.; Sager, W.

2005-12-01

Pairs of young (3.5 Ma) altered and unaltered MORB from the Juan de Fuca Ridge collected from IODP Expedition 301, Hole 1301B were studied to better understand how hydrothermal alteration affects the magnetization of oceanic crust. Thermomagnetic analysis (performed with both a VSM and Kappabridge) revealed characteristically different Curie temperatures and degree of non-reversibility between altered and unaltered samples. Magnetic contributions outlined by these methods, in addition to IRM and hysteresis parameters, indicate that samples are dominated by single domain titanomagnetite and titanomaghemite, with a titanium content of approximately TM45. Petrological analysis with a SEM confirmed the presence of abundant Fe-Ti oxides. Despite the preponderance of titanomagnetite in unaltered samples, shrinkage cracks, which offer direct evidence of maghemitization, were seen in both altered and unaltered samples, indicating (as do irreversible cooling curves for all samples) that even supposedly unaltered samples have undergone some degree of low temperature oxidation. Preliminary paleomagnetic data in related samples indicates normal polarity and inclinations that are approximately what is expected for this site. The samples also exhibit both streaked and well defined, non-streaked magnetizations. This study intends to utilize the information obtained by procedures described above to test for correlations between characteristic magnetization directions and degree of oxidation, in order to further our understanding of the effect maghemitization has on the paleomagnetism of oceanic rocks.

An Integrated Age Model for the Cocos Plate using IODP CRISP Drilling Data

NASA Astrophysics Data System (ADS)

Baxter, A. T.; Kutterolf, S.; Schindlbeck, J. C.; Sandoval, M. I.; Barckhausen, U.; Li, Y. X.; Petronotis, K. E.

2017-12-01

We present an integrated age model for the incoming Cocos Plate sediments offshore Costa Rica. The data, collected over two IODP Expeditions (334 and 344), provides a medium- to high-resolution record from the initial formation of the ocean crust in the Miocene to the present day. This study provides >50 age control points for the CRISP sediments from Sites U1381 and U1414. Although the two sites are just 10 km apart, there are distinct differences in the sediment and tephra record. Most notable is the presence of a hiatus at Site U1381. The hiatus, which is seen at other sites on the Cocos Plate, but not at Site U1414, may be related to erosion due to bottom water currents, mass wasting from Cocos Ridge subduction or may be related to the closure of the Central American Seaway (CAS). Sediment accumulation rates in the Miocene are comparable to modern abyssal plain rates. However, an increase is observed in the Pleistocene, when detritus from the forearc basin appears at Site U1414 2 Ma, shortly after the initiation of Cocos Ridge subduction. A tectonic model is presented that reconstructs the Cocos Plate, from its formation at 23 Ma to the present day. Eastern Equatorial Pacific (EEP) paleoceanographic events, such as the Miocene `carbonate crash' and the Late Miocene-Early Pliocene `biogenic bloom' observed at Site U1414, are also discussed.

Mediterranean Outflow Water at the Pliocene/Pleistocene transition: New stratigraphic constraints from IODP Site U1389 (Gulf of Cadiz, IODP Expedition 339)

NASA Astrophysics Data System (ADS)

Grunert, Patrick; Balestra, Barbara; Auer, Gerald; Flores, José-Abel; Richter, Carl; García Gallardo, Ángela; Röhl, Ulla; Piller, Werner E.

2016-04-01

IODP Hole U1389E, at present located in the lower core of the Mediterranean Outflow Water (MOW) at 640m water depth in the northern Gulf of Cadiz, represents a key-site for the understanding of changes in MOW contribution to the North Atlantic during the late Pliocene and the transition into the Pleistocene ice house climate. Integrated geophysical, micropalaeontological and geochemical proxy records of the recovered sediments imply major changes in MOW strength over the studied interval. However, to consider these data in a broader paleoceanographic and paleoclimatic context, a well-constrained age model is essential. New bio-, chemo-, magnetostratigraphic data and XRF core-scanning suggest that the shipboard age model for the site has to be reconsidered as major changes in the depositional environment have not been recognized in the original, comparably low resolution data-sets. While the new, high-resolution biostratigraphic data confirm the overall time frame of 2.6 to 3.6 Myrs for the studied interval, they also indicate that the last occurrence of Discoaster tamalis in the succession should be reconsidered. New palaeomagnetic data constrain the Gauss normal chron and its subchrons more accurately. Finally, a high-resolution δ18O-record of the planktic foraminifer Globigerinoides ruber allows the identification of many marine isotopic chrons, further refining the stratigraphic framework. Cyclic patterns are recognized in the CaCO3 and TOC contents as well as Ca/Ti- and Zr/Al-ratios. A preliminary cyclostratigraphic analysis of these records in well-recovered intervals suggests an interplay of obliquity and precessional forcing reflected in a change from deposits strongly influenced by terrestrial input (3.0-2.8 Myrs) to deposits strongly affected by MOW (2.8-2.6 Myrs). This study contributes to project P25831-N29 of the Austrian Science Fund (FWF) and is financially supported by grants of ECORD and the Max Kade Foundation.

A Long-Term Geothermal Observatory Spanning Subseafloor Gas Hydrates in IODP Hole U1364A, Cascadia Accretionary Prism

NASA Astrophysics Data System (ADS)

Becker, K.; Davis, E.; Heesemann, M.; McGuire, J. J.; Collins, J. A.; O'Brien, J. K.; von der Heydt, K.

2017-12-01

We report the configuration of and initial results from a 24-thermistor cable installed to 268 m below seafloor (mbsf) in IODP Hole U1364A in the frontal accretionary prism of the Cascadia subduction zone. The thermistor array spans the gas hydrate stability zone and a clear bottom-simulating reflector at 225-230 mbsf. The thermistor string was deployed in July 2016 along with a seismic-strain observatory into the cased section of a pressure-monitoring Advanced CORK (ACORK) that had been installed in 2010 during IODP Expedition 328. Formation pressures are monitored via permeable screens on the outside of solid steel casing that is sealed at the bottom by a bridge plug and cement up to 302 mbsf. All three observatory systems were connected to the Ocean Networks Canada NEPTUNE cabled observatory Clayoquot Slope node in June of 2017, with the thermistor temperatures being logged by ONC every minute. The thermistor array was designed with concentrated vertical spacing around the BSR and two pressure-monitoring screens at 203 and 244 mbsf, with wider thermistor spacing elsewhere to document the geothermal state up to seafloor. The initial six weeks of data logged via the ONC connection show a generally linear temperature gradient, with temperatures of about 15.8°C at the BSR depth, consistent with methane hydrate stability at that depth and pressure. Sensor temperatures at most depths are quite stable over this period, with the exceptions of two sensors at 76 and 256 mbsf that show slowly rising temperatures; these could be due to cellular convection of borehole fluids, sensor degradation, or formation processes, but this requires a longer time series to resolve. We will report updated results after four more months of data recording through November 2017, along with any correlations to the pressure records. The data are freely available to all registered ONC users via the ONC data management and archiving system.

Physical properties of the Nankai inner accretionary prism at Site C0002, IODP Expedition 348

NASA Astrophysics Data System (ADS)

Kitamura, Manami; Kitajima, Hiroko; Henry, Pierre; Valdez, Robert; Josh, Matthew

2014-05-01

Integrated Ocean Drilling Program (IODP) Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) Expedition 348 focused on deepening the existing riser hole at Site C0002 to ~3000 meters below seafloor (mbsf) to access the deep interior of the Miocene inner accretionary prism. This unique tectonic environment, which has never before been sampled in situ by ocean drilling, was characterized through riser drilling, logging while drilling (LWD), mud gas monitoring and sampling, and cuttings and core analysis. Shipboard physical properties measurements including moisture and density (MAD), electrical conductivity, P-wave, natural gamma ray, and magnetic susceptibility measurements were performed mainly on cuttings samples from 870.5 to 3058.5 mbsf, but also on core samples from 2163 and 2204 mbsf. MAD measurements were conducted on seawater-washed cuttings ("bulk cuttings") in two size fractions of >4 mm and 1-4 mm from 870.5 to 3058.5 mbsf, and hand-picked intact cuttings from the >4 mm size fractions within 1222.5-3058.5 mbsf interval. The bulk cuttings show grain density of 2.68 g/cm3 and 2.72 g/cm3, bulk density of 1.9 g/cm3 to 2.2 g/cm3, and porosity of 50% to 32%. Compared to the values on bulk cuttings, the intact cuttings show almost the same grain density (2.66-2.70 g/cm3), but higher bulk density (2.05-2.41 g/cm3) and lower porosity (37-18%), respectively. The grain density agreement suggests that the measurements on both bulk cuttings and intact cuttings are of good quality, and the differences in porosity and density are real, but the values from the bulk cuttings are affected strongly by artifacts of the drilling process. Thus, the bulk density and porosity data on handpicked cuttings are better representative of formation properties. Combined with the MAD measurements on hand-picked intact cuttings and discrete core samples from previous expeditions, porosity generally decreases from ~60% to ~20% from the seafloor to 3000 mbsf at Site C0002. Electrical conductivity and P-wave velocity on discrete samples, which were prepared from both cuttings and core samples in the depth interval of 1745.5-3058.5 mbsf, range 0.15-0.9 S/m and 1.7-4.5 km/s, respectively. The electrical resistivity (a reciprocal of conductivity) on discrete samples is generally higher than the LWD resistivity data but the overall depth trends are similar. On the other hand, the P-wave velocity on discrete samples is lower than the LWD P-wave velocity between 2200 mbsf and 2600 mbsf, while the P-wave velocity on discrete samples and LWD P-wave velocity are in a closer agreement below 2600 mbsf. The electrical conductivity and P-wave velocity on discrete samples corrected for in-situ pressure and temperature will be presented. The shipboard physical properties measurements on cuttings are very limited but can be useful with careful treatment and observation.

Evolution of the Middle Bengal Fan at 8°N in the Oligocene to Pliocene - Preliminary Results from IODP Expedition 354

NASA Astrophysics Data System (ADS)

Volkhard, Spiess; Tilmann, Schwenk; Fenna, Bergmann; Christian, France-Lanord; Adam, Klaus

2016-04-01

Three deep penetration and additional four shallow sites were drilled during IODP Expedition 354 in the Bay of Bengal at 8°N in February-March 2015 across a 320 km-long transect to study Neogene Bengal fan deposition. The three deeper sites located on top of the elevated crustal features of the Ninetyeast Ridge (Site U1451) and 85°Ridge (Site U1455/DSDP Site 218) as well as central between them (Site U1450) shall provide the stratigraphic framework for the Oligocene to Pliocene reconstruction of fan deposition and sedimentary fluxes driven by monsoon evolution and Himalayan erosion and weathering. Based on shipboard biostratigraphy, drilled material reach back in geologic time to the late Miocene (Site U1450), middle Miocene (Site U1455) and Oligocene (Site U1451). While core recovery was generally severely reduced due to the presence of unconsolidated sand and silt units, half-length APC coring technology provided valuable sand samples/recovery down to ~800 meters below seafloor. Increased compaction/diagenesis of units indicating the temporary absence of fan deposition due to major depocenter shifts, comprising of calcarous clay units of mostly pelagic origin, required a change to rotary coring between 600 and 800 mbsf, and thus the presence of sand is mostly uncertain for those deeper sections. However, derived from penetration rates, a high proportion of sand is anticipated back to early Miocene or Oligocene times. The calcareous clay units serve as stratigraphic marker horizons, which turned out to be suitable for seismic correlation across the drilling transect. This in turn allows to determine sedimentary budgets and overall fan growth for numerous time slices. Recovered sediments have Himalayan mineralogical and geochemical signatures suitable to analyze time series of erosion, weathering and changes in source regions as well as impacts on the global carbon cycle. Miocene shifts in terrestrial vegetation, in sediment budget and in style of sediment transport have been tracked. Moderate sedimentation rates. Preliminary seismic stratigraphy also reveals that crustal features evolved since the Miocene thus confining pathways for turbidite transport. The onset of channel-levee structures indentified since ~10 Ma in the seismic records, is correlated with an increase in sediment flux from moderate rates on the order of 30 m/m.y. to an order of magnitude high accumulation rates during phases of sand lobe deposition and levee growth. Expedition 354 has extended the record of early fan deposition by 10 Ma into the Late Oligocene.

Anisotropy of magnetic susceptibility used to detect coring-induced sediment disturbance and filter palaeomagnetic secular variation data: IODP sites M0061 and M0062 (Baltic Sea)

NASA Astrophysics Data System (ADS)

Snowball, Ian; Almqvist, Bjarne; Lougheed, Bryan; Svensson, Anna; Wiers, Steffen; Herrero-Bervera, Emilio

2017-04-01

Inspired by palaeomagnetic data obtained from two sites (M0061 and M0062) cored during IODP Expedition 347 - Baltic Sea Paleoenvironment we studied the Hemsön Alloformation, which is a series of brackish water muds consisting of horizontal planar and parallel laminated (varved) silty clays free from bioturbation. We determined the anisotropy of magnetic susceptibility (AMS) and characteristic remanence (ChRM) directions of a total of 1,102 discrete samples cut from (i) IODP cores recovered by an Advanced Piston corer and (ii) a series of six sediment cores recovered from the same sites by a Kullenberg piston corer. Systematic core splitting, sub-sampling methods and measurements were applied to all sub-samples. We experimentally tested for field-impressed AMS of these muds, in which titanomagnetite carries magnetic remanence and this test was negative. The AMS is likely determined by paramagnetic minerals. As expected for horizontally bedded sediments, the vast majority of the K1 (maximum) and K2 (intermediate) axes had inclinations close to 0 degrees and the AMS shape parameter (T) indicates an oblate fabric. The declinations of the K1 and K2 directions of the sub-samples taken from Kullenberg cores showed a wide distribution around the bedding plane, with no preferred alignment along any specimen axis. Exceptions are samples from the upper 1.5 m of some of these cores, in which the K1 and K2 directions were vertical, the K3 (minimum) axis shallow and T became prolate. We conclude that the Kullenberg corer, which penetrated the top sediments with a pressure of approximately 15 bar, occasionally under-sampled during penetration and vertically stretched the top sediments. Sub-samples from the upper sections of Kullenberg cores had relatively steep ChRM inclinations and we rejected samples that had a prolate, vertically oriented AMS ellipsoid. Surprisingly, the declinations of the K1 axis of all sub-samples taken from IODP APC core sections, which were not oriented relative to each other with respect to azimuth, clustered tightly within the 90-270 degree specimen axis (K2 is within the 0-180 degree axis). This axis is the direction across each cores' split surface (i.e. perpendicular to the "push" direction of the sub-sampling boxes). The APC cores were characterized by various degrees of downwards bending of the planar varves towards the inner surface of the core liner. We conclude that the initial hydraulic pressure applied by the APC, which was consistently above 50 bar during Expedition 347, was needlessly high and created a conical sediment structure and the distinct alignment of the magnetic susceptibility axes along specimen axes. APC core sections with marked disturbances were characterized by ChRM inclinations below 65 degrees, which is a lower limit predicted by time varying geomagnetic field models for the duration of the Hemsö Alloformation (the most recent 6000 years). We rejected samples for palaeomagnetic purposes if the K1 inclination was steeper than 10 degrees. Our study highlights the added value of measuring AMS of discrete sub-samples as an independent control of the suitability of sediments as a source of palaeomagnetic data.

Thermophysical properties derived from lab measurements and downhole logging at New Jersey Shallow Shelf (IODP Expedition 313)

NASA Astrophysics Data System (ADS)

Fehr, A.; Pechnig, R.; Inwood, J.; Lofi, J.; Bosch, F. P.; Clauser, C.

2012-04-01

The IODP drilling expedition 313 New Jersey Shallow Shelf was proposed for obtaining deep sub-seafloor samples and downhole logging measurements in the crucial inner shelf region. The inner to central shelf off-shore New Jersey is an ideal location for studying the history of sea-level changes and its relationship to sequence stratigraphy and onshore/offshore groundwater flows. The region features rapid depositional rates, tectonic stability, and well-preserved, cosmopolitan age control fossils suitable for characterizing the sediments of this margin throughout the time interval of interest. Past sea-level rise and fall is documented in sedimentary layers deposited during Earth's history. In addition, the inner shelf is characterised by relatively fresh pore water intervals alternating vertically with saltier intervals (Mountain et al., 2010). Therefore, three boreholes were drilled in the so-called New Jersey/Mid-Atlantic transect during IODP Expedition 313 New Jersey Shallow Shelf. Numerous questions have arisen concerning the age and origin of the brackish waters recovered offshore at depth. Here we present an analysis of thermophysical properties to be used as input parameters in constructing numerical models for future groundwater flow simulations. Our study is based mainly on Nuclear Magnetic Resonance (NMR) measurements for inferring porosity and permeability, and thermal conductivity. We performed NMR measurements on samples from boreholes M0027A, M0028A and M0029A and thermal conductivity measurements on the whole round cores prior to the Onshore Party. These results are compared with data from alternative laboratory measurements and with petrophysical properties inferred from downhole logging data. We deduced petrophysical properties from downhole logging data and compared them with results obtained with laboratory measurements. In water saturated samples, the number of spins in the fluid is proportional to sample porosity. NMR porosities were calculated from the zero amplitudes of the transverse relaxation measurements by normalizing the CPMG (Carr, Purcell, Meiboom, Gill) amplitudes of the measured samples to the amplitudes measured on a pure water cylinder which is equivalent to a porosity of 100 %. The NMR porosities fit well with porosities determined by Multi Sensor Core Logger (MSCL) and porosity measured on discrete samples using a helium gas pycnometer. Using log interpretation procedures, the volume fraction of different rock types and their porosity can be derived. From the volume fraction of each rock type and its porosity, continuous profiles of thermal conductivity can be derived by using a suitable mixing law, e.g. such as the geometric mean. In combination with thermal conductivity measurements on cores, these continuous thermal conductivity profiles can be calibrated, validated and finally used to provide reliable input parameter for numerical models. The porosity values from NMR seem to correlate well with porosities deduced from other measurements. In order to compare NMR permeabilities, we need permeability determined by an alternative method. The thermal conductivity derived from logs correlates with the measurements performed on cores. In a next step, a numerical model will be set up and the measured thermophysical properties will be implemented in order to study transport processes in passive continental margins. This numerical model will be based on existing geological models deduced from seismic data and drillings.

Ocean Drilling Program: Mirror Sites

Science.gov Websites

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IODP Expedition 351 Izu-Bonin-Mariana Arc Origins: Preliminary Results

NASA Astrophysics Data System (ADS)

Ishizuka, O.; Arculus, R. J.; Bogus, K.

2014-12-01

Understanding how subduction zones initiate and continental crust forms in intraoceanic arcs requires knowledge of the inception and evolution of a representative intraoceanic arc, such as the Izu-Bonin-Mariana (IBM) Arc system. This can be obtained by exploring regions adjacent to an arc, where unequivocal pre-arc crust overlain by undisturbed arc-derived materials exists. IODP Exp. 351 (June-July 2014) specifically targeted evidence for the earliest evolution of the IBM system following inception. Site U1438 (4711 m water depth) is located in the Amami Sankaku Basin (ASB), west of the Kyushu-Palau Ridge (KPR), a paleo-IBM arc. Primary objectives of Exp. 351 were: 1) determine the nature of the crust and mantle pre-existing the IBM arc; 2) identify and model the process of subduction initiation and initial arc crust formation; 3) determine the compositional evolution of the IBM arc during the Paleogene; 4) establish geophysical properties of the ASB. Seismic reflection profiles indicate a ~1.3 km thick sediment layer overlying ~5.5 km thick igneous crust, presumed to be oceanic. This igneous crust seemed likely to be the basement of the IBM arc. Four holes were cored at Site U1438 spanning the entire sediment section and into basement. The cored interval comprises 5 units: uppermost Unit I is hemipelagic sediment with intercalated ash layers, presumably recording explosive volcanism mainly from the Ryukyu and Kyushu arcs; Units II and III host a series of volcaniclastic gravity-flow deposits, likely recording the magmatic history of the IBM Arc from arc initiation until 25 Ma; Siliceous pelagic sediment (Unit IV) underlies these deposits with minimal coarse-grained sediment input and may pre-date arc initiation. Sediment-basement contact occurs at 1461 mbsf. A basaltic lava flow section dominantly composed of plagioclase and clinopyroxene with rare chilled margins continues to the bottom of the Site (1611 mbsf). The expedition successfully recovered pre-IBM Arc basement, a volcanic and geologic record spanning pre-Arc, Arc initiation to remnant Arc stages, which permits testing for subduction initiation and subsequent Arc evolution.

Mega-pockmarks surrounding IODP Site U1414: Insights from the CRISP 3D seismic survey

NASA Astrophysics Data System (ADS)

Nale, S. M.; Kluesner, J. W.; Silver, E. A.; Bangs, N. L.; McIntosh, K. D.; Ranero, C. R.

2013-12-01

Visualization of neural network meta-attribute analyses reveals fluid migration pathways associated with mega-pockmarks within the CRISP 3D seismic volume offshore southern Costa Rica, near site U1414 of IODP Expedition 344. A 245km2 field of mega-pockmarks was imaged on the Cocos Ridge using EM122 multibeam bathymetry, backscatter and 3D seismic reflection aboard R/V Marcus G. Langseth during the 2011 CRISP seismic survey. We utilize the OpendTect software package to calculate supervised neural network meta-attributes within the 3D seismic volume, in order to detect and visualize probable faults and fluid-migration pathways within the sedimentary section of the incoming Cocos plate [see Kluesner et al., this meeting]. Pockmarks imaged within the 3D volume near the trench commonly show a two-tier structure with upper pockmarks located above the steep walls of deeper, older pockmarks. The latter appear to truncate surrounding strata, including widespread high-amplitude reverse polarity reflectors (RPRs), interpreted as trapping horizons. In addition, RPRs are also truncated by positive polarity crosscutting reflections (CCRs), most of which form the base and sides of lens-like structures below the RPRs that are frequently located next to imaged pockmarks. Site U1414 intersects one of these lens-like structures and this appears to correlate to a sharp density and porosity swing observed at ~255 mbsf. In addition, preliminary geochemical analyses from site U1414 show evidence of lateral fluid flow through sediments below the RPR [Expedition 344 Scientists, 2013]. Thus, we interpret the 3D lens-like structures to be pockets of trapped gas and/or over-pressured fluid. Based on 3D imaging we propose a 3-stage pockmark evolution: (1) Overpressure and blowout along RPRs, resulting in pockmark formation, (2) sustained seepage along pockmark walls, resulting in preferential deposition near the center of the pockmark, and (3) rapid burial as pockmarks near the trench axis. On the seafloor, small high-backscatter mounds are found near the walls of a subset of pockmarks, suggesting recent or active seafloor seepage. Further geochemical analyses are needed to determine the source of fluid/gas migration associated with the pockmark structures.

Sedimentologic and Geometric Characterization of Turbidites of Brazos-Trinity Basin IV in the Gulf of Mexico: Preliminary Results of IODP Expedition 308

NASA Astrophysics Data System (ADS)

Gutierrez-Pastor, J.; Pirmez, C.; Flemings, P. B.; Behrmann, J. H.; John, C. M.

2005-12-01

Brazos Trinity Basin IV is located about 200 km offshore Texas, and belongs to a linked system of four intra slope mini basins. Basin IV provides a type section to characterize turbidites in salt withdrawal mini-basins of the Gulf of Mexico. IODP Expedition 308 has cored and logged complete pre-fan and fan sequences that are clearly distinguished with high-resolution seismic profiles at Brazos Trinity Basin IV at Sites U1319, U1320 and U1321. Seismically imaged pre-fan and fan units also can be distinguished and correlated with the sedimentological and logging data. Turbidite facies display distinct properties in terms of grain size, bed thickness, color, organic matter content, vertical organization of beds and lateral distribution in all the units of the fan through the basin. The pre-fan sequence is composed of terrigenous laminated clay with color banding and it is interpreted to result from deposition from fluvial plumes and/or muddy turbidity currents overspilling from basins upstream of Basin IV. The lower fan is characterized by laminated and bioturbated muds with thin beds of silt and sand, and represent the initial infill of the basin by mostly muddy turbidity currents, although an exceptionally sand-rich unit occurs at the base of the lower fan. The middle and upper fan represent the main pulses of turbidity current influx into Basin IV, and contain fine to medium sand turbidite beds organized in packets ranging in thickness from 5 to 25 m. The middle fan displays an overall upward increase in sand content at Site U1320, suggesting increased flow by-pass from the updip basins through time. Key examples of turbidites from each fan unit are analysed in detail to infer the depositional processes and infilling history of Brazos-Trinity Basin IV. The study of turbidites in a calibrated basin such as Basin IV provides ground truth for the sedimentological processes and resultant seismic facies, which can be used to interpret the infill history of other intraslope basins with similar seismic facies in the Gulf of Mexico where well calibration is not available.

Pore Water Chemistry as Sensitive Indicators for Fluid Flow in Brazos-Trinity Basin #4 and Ursa Basin, Northeast Gulf of Mexico (IODP Expedition 308)

NASA Astrophysics Data System (ADS)

Jiang, S.; Gilhooly, W.; Takano, Y.; Flemings, P.; Behrmann, J.; John, C.

2005-12-01

Rapid sediment loading drives overpressure in marine sedimentary basins around the world. During IODP Expedition 308, two basins (Brazos-Trinity Basin #4 and Ursa Basin) with large different sedimentary loading of turbidite and hemipelagic sediments in the northeast Gulf of Mexico, were investigated to characterize in-situ spatial variations in temperature, pressure, and rock and fluid physical properties and chemistry. Pore water chemical compositions including alkalinity, salinity, pH, anions (Cl, SO4, PO4, H4SiO4), cations (Na, K, Ca, Mg), trace metals (Li, B, Sr, Ba, Fe, Mn), were analyzed in four drill holes at sites U1319, U1320, U1322, and U1324, in the Brazos-Trinity Basin #4 and Ursa Basin. At all sites, pore water chemistry shows great variability at shallow depths with maximam or miminum values corresponding well to seismic reflectors and lithostratigraphic units. The sulfate profile shows a dramatic decrease in SO4 content with a sulfate-methane interface (SMI) of 15 mbsf at Site 1319 and 22 mbsf at Site 1320 in the Brazos-Trinity Basin #4 Basin. In contrast, the sulfate- methane interfaces (SMI) are much deeper in Ursa Basin, i.e., 74 mbsf at Site 1322, and 94 mbsf at Site 2324. The deep SMI in Ursa Basin suggest relatively slow anaerobic degradation of organic matter considering the location of drilling site though we do not determine sulfate reducing rate with organic matter or methane as substrate at this leg. The downhole consumption of sulfate coincides with a concomitant increase in alkalinity and a decrease of Mn, Ca, Mg, Sr, and Li. Furthermore, initial pore water chemistry results appear to be influence by hydrogeologic fluid flow in both basins. Coincidence between pore water profile concentration maxima and parallel seismic reflectors may suggest that these seismic surfaces occur along specific stratigraphic units, which serve as channels for lateral fluid flow. Overall, the downhole variations in interstitial water chemistry may reflect a combination of processes, including anaerobic degradation of organic matter, diagenetic carbonate precipitation/dissolution, and fluid flow pathways.

Marine Subsurface Microbial Communities Across a Hydrothermal Gradient in Okinawa Trough Sediments

NASA Astrophysics Data System (ADS)

Brandt, L. D.; Hser Wah Saw, J.; Ettema, T.; House, C. H.

2015-12-01

IODP Expedition 331 to the Okinawa backarc basin provided an opportunity to study the microbial stratigraphy within the sediments surrounding a hydrothermal vent. The Okinawa backarc basin is a sedimented region of the seafloor located on a continental margin, and also hosts a hydrothermal network within the subsurface. Site C0014 within the Iheya North hydrothermal field is located 450 m east of the active vent and has a surface temperature of 5°C with no evidence of hydrothermal alteration within the top 10 meters below sea floor (mbsf). Temperature increases with depth at an estimated rate of 3°C/m and transitions from non-hydrothermal margin sediments to a hydrothermally altered regime below 10 mbsf. In this study, we utilized deep 16S rRNA sequencing of DNA from IODP Expedition 331 Site C0014 sediment horizons in order to assess diversity throughout the sediment column as well as determine the potential limits of the biosphere. Analysis of the amplicon data shows a shift over 15 mbsf from a heterogeneous community of cosmopolitan marine subsurface taxa toward an archaeal-dominated community in the deepest horizons of the predicted biosphere. Notably, the phylum Chloroflexi represents a substantial taxon through most horizons, where it appears to be replaced below 10 mbsf by punctuations of thermophilic and methanotrophic Archaea and Miscellaneous Crenarchaeotic Group abundances. DNA from the aforementioned transition horizons was further analyzed using metagenomic sequencing. Preliminary taxonomic analysis of the metagenomic data agrees well with amplicon data in capturing the shift in relative abundance of Archaea increasing with depth. Additionally, reverse gyrase, a gene found exclusively in hyperthermophilic microorganisms, was recovered only in the metagenome of the deepest horizon. A BLAST search of this protein sequence against the GenBank non-redudnant protein database produced top hits with reverse gyrase from Thermococcus and Pyrococcus, which are known thermophiles. Up until now, thermophiles and hyperthermophiles have been studied in cultured hydrothermal vent fluid samples, or have been identified from 16S rRNA taxonomic analyses. These recovered genes provide direct evidence for a pervasive subsurface hyperthermophilic biosphere in off-axis hydrothermal sediments.

Biogenic opal production changes in the Gulf of Alaska (IODP Expedition 341 Site U1417) during the Pliocene to Miocene

NASA Astrophysics Data System (ADS)

Khim, B. K.; Kim, S.; Asahi, H.

2016-12-01

IODP Expedition 341 Site U1417 (56o57.59'N, 147o6.59'W, 4200 m) is located in the distal Surveyor Fan in the Gulf of Alaska, Northeast Pacific. In this study, we documented biogenic opal content and its mass accumulation rate using a total of 445 sediments from Hole U1417D (below core 43X, 275 CSF-A m) and from Hole U1417E (below core 14R, 465 CSF-A m) which were assigned to Pliocene-Miocene epoch on the basis of shipboard age model. Biogenic opal content and MAR were generally low (<10% and 0.5 g/cm2/kyr, respectively) throughout the core. A significant offset of biogenic opal contents between Site U1417 and Site 887 (54o21.9'N, 148o26.8'W, 3633 m) is observed; much lower at Site U1417. However, biogenic opal content was distinctively high (20 to 40%) at 23 Ma, 15 Ma, 12 Ma, and 8 Ma, which correspond to the lithologic unit changes. These intervals are also characterized by low NGR, MS, and linear sedimentation rate (LSR), indicating the sediment deposition under warm climate/less glacier influence. Thus, the intervals seem to correspond to climatic optimums during the Miocene. Based on terrigenous MAR at Site 887, terrigenous materials supplied by glacial denudation increased greatly since the Northern Hemisphere Glaciation (NHG; 3.5-2.5 Ma). However, Site U1417 shows that high MS representing the terrestrial input occurred far earlier since 8 Ma. It may imply that the formation of glacier in the Gulf of Alaska began earlier or that terrestrial material input was enhanced by sea-ice or turbidite. Intermittent peaks of biogenic opal content and MAR after 8 Ma coincided with the occurrence of cold water/littoral and neritic diatoms and deep cold water radiolarian species, which is likely related to gradual glaciation. Biogenic opal productivity was high during the early Pliocene (5-3.5 Ma), and then it decreased during the NHG.

Seamount subduction and serpentinite mud volcanisms in the Mariana convergent margin system: time constraints from micropaleontological studies (IODP Expedition 366)

NASA Astrophysics Data System (ADS)

Kurz, W.; Micheuz, P.; Grunert, P.; Auer, G.; Reuter, M.

2017-12-01

IODP Expedition 366 recovered core from three serpentinite mud volcanoes at increasing distances from the Mariana trench subduction zone along a south-to-north transect: Yinazao (Blue Moon), Fantangisña (Celestial), and Asùt Tesoru (Big Blue). Cores consist of serpentinite mud containing lithic clasts and minerals derived from the underlying forearc lithosphere, and from the subducting Pacific Plate. A preliminary screening for micro- and nannofossils from Asùt Tesoru revealed assemblages of planktic and benthic foraminifera and calcareous nannoplankton containing biostratigraphic marker species (e.g., Globigerinella calida, Globorotalia flexuosa, Gr. truncatulinoides Gr. tumida, Sphaeroidinella dehiscens amongst planktic foraminifera; Gephyrocapsa spp., Pseudoemiliania lacunosa, Reticulosfenestra asanoi amongst calcareous nannoplankton). This provides a robust stratigraphic framework and age assessment (from ca. 0.2 to 8.0 Ma from top to bottom) of distinct sediment and serpentinite mud flow layers. Recycled materials from the subducted slab include fault rocks, metamorphosed pelagic sediments, diagenetic shallow water reef assemblages, and metavolcanic rocks. The recycled materials are found at all three mud volcanoes and are interpreted to be parts of subducted Pacific plate seamounts, presumably Cretaceous in age. Core U1491C (Yinazao) recovered a Miogypsina rudstone cobble that could have derived from more than 10 km beneath the forearc sea floor, with lithoclasts and coralline, red-algal grainstone matrix, altogether showing diagenetic overprint. Although parts of subducted Pacific plate seamounts are assumed be Cretaceous in age, the presence of Miogypsina suggests a Miocene age, thus may represent the latest, uppermost part of a Pacific Plate seamount. The assemblage represents a shallow water (photic zone) environment. Assuming a Pacific plate velocity of 5 cm per year the hypothetical Guyot was several hundred kilometers east of the trench at Late Miocene times (500 to 750 km), most likely outside the fore-trench bulge. Taking the recent Pacific plate WNW movement direction, and tracing back these 500 or more kilometers, it would have been located in the area of today's Micronesia atolls where comparable shallow water conditions exist.

The Paleocene-Eocene "Greenhouse" Arctic Ocean paleoenvironment: Implications from biomarker results from IODP Expedition 302 (ACEX)

NASA Astrophysics Data System (ADS)

Weller, P.; Stein, R.

2006-12-01

In order to reconstruct the long-term Cenozoic climate history of the central Arctic Ocean and its role in earth's transition from Paleogene greenhouse to the Neogene icehouse conditions, IODP Expedition 302 (Arctic Ocean Coring Experiment ACEX) visited the Lomonosov Ridge in August 2004. Here, we present new data of organic-geochemical compounds determined in ACEX sediment samples to identify organic matter sources and biomarker proxies to decipher processes controlling organic-carbon accumulation and their paleo- environmental significance. Of special interest was the reconstruction of organic carbon composition, preservation and accumulation (i.e. high productivity vs. anoxia vs. terrigenous input) during periods of extreme global warmth and proposed increased freshwater discharge in the early Cenozoic. Specific source-related biomarkers (e.g. n-alkanes, fatty acids, isoprenoids, carotenoids, steranes/sterenes, hopanes/hopenes, hopanoic acids, aromatic terpenoids, benzohopanes, long-chain alkenones, organic sulfur compounds) and Rock-Eval parameters were determined in the ACEX sediment samples, ranging from the late Paleocene to the middle Miocene in age. The records show highly variable TOC-contents and a large variety and variability of compounds derived from marine, terrestrial and bacterial origin. The distribution of hopanoic acid isomers was dominated by compounds with the biological 17 beta (H), 21 beta (H) configuration indicating a low level of maturity, which was in good agreement with the data from Rock-Eval pyrolysis. Based on the biomarker data, the terrestrial organic matter supply was significantly enriched during the late Paleocene and part of the early Eocene, whereas n-alkanes and n-fatty acids in samples from the PETM and Elmo events as well as the middle Eocene indicate increased aquatic contributions. Furthermore samples from the middle Eocene were characterized by the occurrence of long-chain alkenones, high proportions of lycopane and high ratios (>0.6) of (n-C35+lycopane)/n-C31. Interestingly, lycopane which might indicate photic-zone anoxia was not detected in co-occurrence with highly source-specific isorenieratene derivates.The occurrence in samples of the "freshwater" Azolla-event suggest that lycopane was more likely derived from freshwater algae (Botriococcus braunii, race L genus).

Mineralogy and Isotopic Records of Carbonate and Silicate Cementation of the Siliciclastic Sediments of the New Jersey Shelf (IODP Expedition 313)

NASA Astrophysics Data System (ADS)

Pierre, C.; Blanc-Valleron, M. M.; Lofi, J.

2016-12-01

The New Jersey continental shelf extends up to 150 km away from the shoreline. During IODP Expedition 313 the siliciclastic deposits of late Eocene to late Pleistocene age were drilled down to 631 mbsf, 669 mbsf and 700 mbsf at the three sites 27A, 28A, 29A respectively, in very shallow water depth (33.5 to 36 m). Pore water salinities display multilayered fresh-salty-brine units 10 to 170 m thick, where freshwater is preferentially stored in fine-grained sediments (van Geldern et al 2013 ; Lofi et al 2013). The sharp boundaries of these buried aquifers are often marked by hardly cemented layers a few centimeters thick. The mineralogy and SEM observations of these layers show two phases of cementation by authigenic minerals : (1) the early carbonate cement is made of Fe-dolomite, ankerite and occasionally calcite, frequently associated with pyrite (2) the late silicate cement (silica, K-Fe-rich clay minerals, zeolites) fills in the residual porosity. The isotopic compositions of the carbonate cements vary in wide ranges : -2.4 < δ18O‰ VPDB < +2.8 ; -15.1< δ13C ‰ VPDB <+15.6. The δ18O values indicate carbonate precipitation with pore waters more or less depleted in 18O of the buried aquifers. The δ13C values of carbonate are related to organic matter diagenesis providing 13C-depleted DIC during bacterial sulphate reduction (with pyrite as a by-product of the reaction) and 13C-rich DIC during methanogenesis. The diagenetic cementation processes included chemical weathering of reactive silicate minerals by the CO2-rich pore waters issued from organic matter diagenesis that released bicarbonate, cations and dissolved silica, which were further precipitated as carbonate and silicate cements. The temperature estimated (18 ± 4°C) for the precipitation of carbonate indicates that cementation occurred at moderate burial depths, i.e. probably very soon after deposition. Lofi J et al 2013. Geosphere, 9, 4, 1009-1024 Van Geldern R et al 2013. Geosphere, 9, 1, 96-112

IODP Expedition 338: Riser and Riserless Drilling Along the NanTroSEIZE Transect

NASA Astrophysics Data System (ADS)

Strasser, M.; Moore, G. F.; Dugan, B.; Kanagawa, K.; Toczko, S.

2013-12-01

Integrated Ocean Drilling Program (IODP) Expedition 338 provided new constraints on the Kumano Basin sediments, the accretionary prism inner wedge, the seaward extension of the megasplay fault, the architecture and mechanics of landslides, and the alteration of oceanic basement of the incoming Philippine Sea plate. This was accomplished through riser and riserless drilling, logging while drilling (LWD), and cuttings and core analysis. Cuttings and LWD analyses at Hole C0002F reveal two lithologic units in the prism inner wedge which are separated by a prominent fault zone at ~1640 mbsf. Mud-gases from the inner prism show high concentrations at the top of the wedge that decrease, but become more thermogenic, with depth. These data are from the previously unaccessed deeper part of the Nankai accretionary prism. Riserless coring at Site C0002 provided data across the gas hydrate zone of the Kumano Basin, across the Kumano Basin-accretionary prism unconformity, and in the uppermost accretionary prism. Within the Kumano basin section, gas and porewater geochemistry documents microbial methane gas in hydrates that are disseminated in sandy layers. Multiple penetrations of the Kumano Basin-accretionary prism boundary and 3D seismic data show that the boundary is erosive and complex. LWD (Site C0018) and coring and LWD (Site C0021) augment existing data to better understand submarine landslide dynamics and mass-transport deposit (MTD) emplacement processes. Previous coring at Site C0018 identified six MTDs, but only two MTD intervals were detected in resistivity images that show high angle, randomly oriented bedding. Site C0021, located more proximal to the MTD source, provides constraint on MTD variability. Correlation across the sites reveals a thick MTD with an erosional base characterized by a shear zone in muddy sediments vs. a translational basal surface within coarse volcaniclastic sand in the proximal and distal/lateral areas, respectively. LWD data and cores from Site C0022 characterize the uppermost 400 m of sediment near the tip of the megasplay fault zone where it approaches the seafloor. This fault zone is inferred to be located at the interval of 80-145 mbsf, based on biostratigraphic reversals, bedding dips >20°, porosity anomalies and a change in trend of interstitial water chemistry data. LWD at Site C0012 primarily yielded insights into the nature of the incoming oceanic crust. Two crustal units were identified based on LWD data. The upper unit had gamma ray variations that may indicate changes in the crustal alteration or sediment-basalt interlayering. The deeper unit has little variation in log properties, suggesting the presence of uniform or fresh basalt. Together these data provide new constraints on the overall architecture and mechanics of the Nankai subduction zone.

Late Eocene to middle Miocene (33 to 13 million years ago) vegetation and climate development on the North American Atlantic Coastal Plain (IODP Expedition 313, Site M0027)

NASA Astrophysics Data System (ADS)

Kotthoff, U.; Greenwood, D. R.; McCarthy, F. M. G.; Müller-Navarra, K.; Prader, S.; Hesselbo, S. P.

2014-08-01

We investigated the palynology of sediment cores from Site M0027 of IODP (Integrated Ocean Drilling Program) Expedition 313 on the New Jersey shallow shelf to examine vegetation and climate dynamics on the east coast of North America between 33 and 13 million years ago and to assess the impact of over-regional climate events on the region. Palynological results are complemented with pollen-based quantitative climate reconstructions. Our results indicate that the hinterland vegetation of the New Jersey shelf was characterized by oak-hickory forests in the lowlands and conifer-dominated vegetation in the highlands from the early Oligocene to the middle Miocene. The Oligocene witnessed several expansions of conifer forest, probably related to cooling events. The pollen-based climate data imply an increase in annual temperatures from ∼11.5 °C to more than 16 °C during the Oligocene. The Mi-1 cooling event at the onset of the Miocene is reflected by an expansion of conifers and mean annual temperature decrease of ∼4 °C, from ∼16 °C to ∼12 °C around 23 million years before present. Relatively low annual temperatures are also recorded for several samples during an interval around ∼20 million years before present, which may reflect the Mi-1a and the Mi-1aa cooling events. Generally, the Miocene ecosystem and climate conditions were very similar to those of the Oligocene. Miocene grasslands, as known from other areas in the USA during that time period, are not evident for the hinterland of the New Jersey shelf, possibly reflecting moisture from the proto-Gulf Stream. The palaeovegetation data reveal stable conditions during the mid-Miocene climatic optimum at ∼15 million years before present, with only a minor increase in deciduous-evergreen mixed forest taxa and a decrease in swamp forest taxa. Pollen-based annual temperature reconstructions show average annual temperatures of ∼14 °C during the mid-Miocene climatic optimum, ∼2 °C higher than today, but ∼1.5 °C lower than preceding and following phases of the Miocene. We conclude that vegetation and regional climate in the hinterland of the New Jersey shelf did not react as sensitively to Oligocene and Miocene climate changes as other regions in North America or Europe due to the moderating effects of the North Atlantic. An additional explanation for the relatively low regional temperatures reconstructed for the mid-Miocene climatic optimum could be an uplift of the Appalachian Mountains during the Miocene, which would also have influenced the catchment area of our pollen record.

An Investigation of the Outward Bound Final Expedition

ERIC Educational Resources Information Center

Bobilya, Andrew J.; Kalisch, Ken; Daniel, Brad

2011-01-01

Research of wilderness programs indicates a clear need for additional investigation of specific program components and their influence on participant outcomes. This study examines one component of the Outward Bound wilderness program--the Final Expedition. The Final Expedition is a student-led wilderness expedition and is also referred to as an…

The Impact of Fe-Ti Oxide Concentration on the Structural Rigidity of the Lower Oceanic Crust, Atlantis Bank, Southwest Indian Ridge

NASA Astrophysics Data System (ADS)

Deans, J. R.; Winkler, D. A.

2017-12-01

Fe-Ti oxides are important components of oceanic core complexes (OCC) formed at slow-spreading ridges, since Fe-Ti oxide phases form throughout the crustal column and are weaker than silicate phases. This study investigated the predicted relationship between the presence and concentration of Fe-Ti oxides and the presence/intensity of crystal-plastic deformation in samples from Atlantis Bank, Southwest Indian Ridge (SWIR). Atlantis Bank is an OCC that formed through the exhumation of lower oceanic crust along a detachment shear zone/fault. OCCs form along slow-spreading ridges and are characterized by the complex interactions between magmatism and crustal extension, thus, making them more susceptible to crystal-plastic deformation at higher temperatures and for weaker phases like Fe-Ti oxides to preferentially partition strain. Atlantis Bank has been the focus of many scientific expeditions to various sites including; Ocean Drilling Program (ODP) Holes 735B and 1105A, and the International Oceanic Discovery Program (IODP) Hole U1473A. A total of 589 thin sections from all three holes were analyzed using the software package Fiji to calculate the Fe-Ti oxide concentration within the thin sections. The Fe-Ti oxide percentage was correlated with the crystal-plastic fabric (CPF) intensity, from 0-5 (no foliation - ultramylonite), for each thin section using the statistical software R. All three holes show a positive correlation between the abundance of Fe-Ti oxides and the CPF intensity. Specifically, 76.3% of samples with a concentration of 5% or more Fe-Ti oxides have a corresponding CPF intensity value of 2 or more (porphyroclastic foliation - ultramylonitic). The positive correlation may be explained by the Fe-Ti oxides preferentially partitioning strain, especially at temperatures below where dry plagioclase can recrystallize. This allows for a mechanism of continued slip along the shear zone or form new shear zones at amphibolite grade conditions while the lower crust is being exhumed. Additionally, IODP U1473A and ODP 1105A had similar correlation values of 0.11 (on a scale of -1 to 1), whereas ODP Hole 735B had double the correlation value of 0.24. Since ODP Hole 735B has older rocks than the other two holes, it may have recorded more deformation comparatively speaking.

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Methane-related metabolisms of deep-sea sediments captured with a colonization experiment.

NASA Astrophysics Data System (ADS)

Carr, S. A.; Wheat, C. G.; Orcutt, B.; Kopf, A.; Saffer, D. M.; Toczko, S.

2016-12-01

NanTroSEIZE is a multi-expedition project of the International Ocean Discovery Program (IODP) designed to investigate the Nankai Trough subduction zone. In 2016, a long-term borehole instrument package known as the "GeniusPlug" was collected from Hole C0010A after a six-year deployment within the sediment of a major fault zone, at a depth of 400 mbsf. This GeniusPlug included a set of osmotically-driven pumps, which continuously pumped in situ deep seated, formation water through a microbiological colonization experiment (flow-through osmo colonization system (FLOCS)). This FLOCS experiment contained cassettes of olivine, barite, and sediment collected from nearby Hole C0004D, to serve as colonization substrates. While similar FLOCS have been deployed within boreholes in the igneous oceanic crust, this FLOCS experiment represents the first to be deployed within a sedimentary environment, and thus represents the first opportunity to observe how pore water communities colonize sediment and rock substrates. Initial geochemistry results suggest that conditions within the FLOCS experiment were similar to a methane-sulfate transition zone, and initial enrichment cultures inoculated with the FLOCS substrates demonstrate methane production. Here, we will present integrated results of culturing experiments and culture-independent genomic investigations as a means to elucidate the methane-related metabolisms of these colonizing communities.

When did Mediterranean Outflow Water begin to circulate into the North Atlantic?

NASA Astrophysics Data System (ADS)

Hernández Molina, Francisco Javier; Stow, Dorrik A. V.; Zarikian, Carlos

2014-05-01

The southwestern Iberian margin records critical evidence of Mediterranean Outflow Water (MOW) following its exit through the Strait of Gibraltar. Data collected during Integrated Ocean Drilling Program (IODP) Expedition 339 provide new constraints on MOW circulation patterns from Pliocene to present time, which indicate an alternative sequence of events in the establishment of global ocean circulation patterns. Following the opening of the Strait of Gibraltar (5.46 Ma), a limited volume of weak MOW entered the Atlantic at about 4.5- 4.2 Ma. Two depositional hiatuses evident at 3.2-3.0 Ma and 2.4-2.1 Ma indicate that significant MOW circulation into the North Atlantic did not occur until the Late Pliocene and early Pleistocene. These hiatuses accompany other changes in sedimentary processes. A younger event at 0.9-0.7 Ma suggests additional Pleistocene phase of MOW intensification. These events are coeval with global changes in deep-water sedimentation associated with shifts in global thermohaline circulation (THC). The events evident from sediment cores and seismic records interpreted here suggest that MOW provided an important, additional component of warm, saline waters to northern latitudes, thus enhancing Atlantic Meridional Overturning Circulation (AMOC). Similar changes have been globally described, suggesting a link between climatic shifts, THC and plate tectonic events.

Orbital-scale denitrification changes in the Eastern Arabian Sea during the last 800 kyrs.

PubMed

Kim, Ji-Eun; Khim, Boo-Keun; Ikehara, Minoru; Lee, Jongmin

2018-05-04

Denitrification in the Arabian Sea is closely related to the monsoon-induced upwelling and subsequent phytoplankton production in the surface water. The δ 15 N values of bulk sediments collected at Site U1456 of the International Ocean Discovery Program (IODP) Expedition 355 reveal the orbital-scale denitrification history in response to the Indian Monsoon. Age reconstruction based on the correlation of planktonic foraminifera (Globigerinoides ruber) δ 18 O values with the LR04 stack together with the shipboard biostratigraphic and paleomagnetic data assigns the study interval to be 1.2 Ma. Comparison of δ 15 N values during the last 800 kyrs between Site U1456 (Eastern Arabian Sea) and Site 722B (Western Arabian Sea) showed that δ 15 N values were high during interglacial periods, indicating intensified denitrification, while the opposite was observed during glacial periods. Taking 6‰ as the empirical threshold of denitrification, the Eastern Arabian Sea has experienced a persistent oxygen minimum zone (OMZ) to maintain strong denitrification whereas the Western Arabian Sea has undergone OMZ breakdown during some glacial periods. The results of this study also suggests that five principal oceanographic conditions were changed in response to the Indian Monsoon following the interglacial and glacial cycles, which controls the degree of denitrification in the Arabian Sea.

Gas hydrate drilling transect across northern Cascadia margin - IODP Expedition 311

USGS Publications Warehouse

Riedel, M.; Collett, T.; Malone, M.J.; Collett, T.S.; Mitchell, M.; Guerin, G.; Akiba, F.; Blanc-Valleron, M.; Ellis, M.; Hashimoto, Y.; Heuer, V.; Higashi, Y.; Holland, M.; Jackson, P.D.; Kaneko, M.; Kastner, M.; Kim, J.-H.; Kitajima, H.; Long, P.E.; Malinverno, A.; Myers, Gwen E.; Palekar, L.D.; Pohlman, J.; Schultheiss, P.; Teichert, B.; Torres, M.E.; Trehu, A.M.; Wang, Jingyuan; Worthmann, U.G.; Yoshioka, H.

2009-01-01

A transect of four sites (U1325, U1326, U1327 and U1329) across the northern Cascadia margin was established during Integrated Ocean Drilling Program Expedition 311 to study the occurrence and formation of gas hydrate in accretionary complexes. In addition to the transect sites, a fifth site (U1328) was established at a cold vent with active fluid flow. The four transect sites represent different typical geological environments of gas hydrate occurrence across the northern Cascadia margin from the earliest occurrence on the westernmost first accreted ridge (Site U1326) to the eastward limit of the gas hydrate occurrence in shallower water (Site U1329). Expedition 311 complements previous gas hydrate studies along the Cascadia accretionary complex, especially ODP Leg 146 and Leg 204 by extending the aperture of the transect sampled and introducing new tools to systematically quantify the gas hydrate content of the sediments. Among the most significant findings of the expedition was the occurrence of up to 20 m thick sand-rich turbidite intervals with gas hydrate concentrations locally exceeding 50% of the pore space at Sites U1326 and U1327. Moreover, these anomalous gas hydrate intervals occur at unexpectedly shallow depths of 50-120 metres below seafloor, which is the opposite of what was expected from previous models of gas hydrate formation in accretionary complexes, where gas hydrate was predicted to be more concentrated near the base of the gas hydrate stability zone just above the bottom-simulating reflector. Gas hydrate appears to be mainly concentrated in turbidite sand layers. During Expedition 311, the visual correlation of gas hydrate with sand layers was clearly and repeatedly documented, strongly supporting the importance of grain size in controlling gas hydrate occurrence. The results from the transect sites provide evidence for a structurally complex, lithology-controlled gas hydrate environment on the northern Cascadia margin. Local shallow occurrences of high gas hydrate concentrations contradict the previous model of gas hydrate formation at an accretionary prism. However, long-lived fluid flow (part of the old model) is still required to explain the shallow high gas hydrate concentrations, although it is most likely not pervasive throughout the entire accretionary prism, but rather localized and focused by the tectonic processes. Differences in the fluid flow regime across all of the transect drill sites indicate site-specific and probably disconnected (compartmented) deeper fluid sources in the various parts of the accretionary prism. The data and future analyses will yield a better understanding of the geologic controls, evolution and ultimate fate of gas hydrate in an accretionary prism as an important contribution to the role of gas hydrate methane gas in slope stability and possibly in climate change. ?? The Geological Society of London 2009.

Hydrodynamic Conditions Influencing Cold-Water Coral Carbonate Mound Development (Challenger Mound, Porcupine Seabight, NE Atlantic): a Contribution to IODP Exp307

NASA Astrophysics Data System (ADS)

Thierens, M.; Odonnell, R.; Stuut, J.; Titschack, J.; Dorschel, B.; Wheeler, A. J.

2007-12-01

Cold-water coral carbonate mounds are complex geo-biological systems, originating from the interplay of hydrodynamic, sedimentological and biological factors. As changes in hydrodynamic and sedimentary regime are assumed to be amongst the main controls on mound evolution, reconstruction of the hydrodynamic and palaeoclimatic microenvironment on-mound, compared to the background environmental conditions (as seen off- mound), contributes to the fundamental understanding of these intriguing features and the development of a cold- water coral carbonate mound development model. Challenger Mound, one of the large cold-water coral carbonate mounds along the eastern Porcupine Seabight continental margin (NE Atlantic, SW off Ireland), was successfully drilled during IODP Expedition 307, providing the first complete recovery of a continuous sedimentary sequence through a carbonate mound. High-resolution particle size analysis of the terrigenous sediment component is used as primary proxy for reconstructing the hydrodynamic conditions during mound development. First results indicate repeated shifts in hydrodynamic conditions during sediment deposition on Challenger Mound, from lower-energetic conditions to higher-energetic environments and visa versa, which might reflect environmental variation over interglacial-glacial timescales throughout the whole mound development period. In conjunction with other available data, this dataset provides insight in local current regimes and sediment dynamics, the specific role of cold-water corals in these complex geo-biological systems and the differentiation of different sediment contributors to the coral mound system and its surroundings.

Stress geomechanical model application: Stress tensor evaluation in recent Nankai subduction zone, SW Japan

NASA Astrophysics Data System (ADS)

Wu, H. Y.; Chan, C. H.

2016-12-01

Nowadays, IODP keeps investigating the scientific drilling in Nakai of southwest Japan from 2006. During this decade, we collected the massive logging data and core samples in this area for determining the stress evolution in this interseimic period after 1944 Tonakai earthquake. One of key assumption in Nankai seismogenic zone is the stress accumulation on the plate boundary should be the thrust-fault stress regime (SHmax>Shmin> Sv). In this research, the slip-deficit model is used to determine the wide scale stress field. The drilled IODP well sites are designed to be the fine control points. Based on the multiple ICDP expeditions near the Nankai trough (C0002A, F, and P) in different depths, the three dimensional stress estimation can be confirmed with the lateral boreholes loggings. Even the recently drilling did not reach the subduction zone, our model provides the considerable results by the reliable boundary conditions. This model simulated the stress orientation and magnitude generated by the slip-deficit model, area seismicity, and borehole loggings. Our results indicated that the stress state keeps in normal-faulting stress regime in our research area, even near the Nankai trough. Although the stress magnitude is increasing with the depth, one of horizontal principal stresses (Shmin) is hardly greater than the vertical stress (over-burden weight) in the reachable depth (>10km). This result implies the pore-pressure anomaly would happen during the slip and the stress state would be varied in different stages when event occurred

Ocean Drilling Program: Janus Web Database

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in Janus Data Types and Examples Leg 199, sunrise. Janus Web Database ODP and IODP data are stored in as time permits (see Database Overview for available data). Data are available to everyone. There are

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/TAMRF Human Resources For updated policies and forms, see the IODP-USIO Human Resources web site. For additional information contact: Kim Johnson Supervisor of Human Resources and Insurance Services Ocean

Anomalously high porosity in subduction inputs to the Nankai Trough (SW Japan) potentially caused by volcanic ash and pumice

NASA Astrophysics Data System (ADS)

Huepers, A.; Ikari, M.; Underwood, M.; Kopf, A.

2013-12-01

At convergent margins, the sedimentary section seaward of the trench on the subducting oceanic lithosphere provides the source material for accretionary prisms and eventually becomes the host rock of the plate boundary megathrust. The mechanical properties of the sediments seaward of the subduction zone have therefore a first order control on subduction zone forearc mechanics and hydrogeology. At the Nankai Trough (SW Japan) the majority of sediment approaching the subduction zone is clay-rich. Scientific drilling expeditions in the framework of the Ocean Drilling Program (ODP) and the Integrated Ocean Drilling Program (IODP) have revealed an anomalous zone of high porosity in a major lithologic unit known as the Upper Shikoku Basin facies (USB), which is associated with elevated volcanic ash content and high amounts of silica in the interstitial water. The existence of the high porosity zone has previously been associated with advanced silica cementation, driven by the dual diagenetic transition of opal-A to opal-CT, and opal-CT to quartz. However, temperature estimates from recent drilling expeditions offshore the Kii peninsula reveal different in situ temperatures at the proposed diagenetic boundary in the Shikoku Basin. Furthermore, laboratory measurements using core samples from the USB show that cohesive strength is not elevated in the high porosity zone, suggesting that a process other than cementation may be responsible. The USB sediment is characterized by abundant volcanic ash and pumice, therefore the high porosity zone in the USB may be closely linked to the mechanical behavior of this phase. We conducted consolidation tests in the range 0.1 to 8 MPa effective vertical stress on artificial ash-smectite and pumice-smectite mixtures, as well as intact and remolded natural samples from the IODP Sites C0011 and C0012 to investigate the role of the volcanic constituent on porosity loss with progressive burial. Our results show that both remolded and intact natural samples have high porosities of up to ~71 to 75% at a vertical effective stress of 0.1 MPa, which decreases to 39 to 49% at 8 MPa vertical effective stress. The behavior of the remolded samples is in good accordance with compiled in-situ porosity vs. depth profiles from the high porosity zone. This suggests that cementation is not the cause for the anomalously high porosity. The consolidation tests on the artificial samples document that pure ash and pumice samples are highly resistant to consolidation. Between 0.1 to 8 MPa vertical effective stress, the porosity decreases from 51 to 47% for the ash sample and 60% to 46% for the pumice sample. The higher initial porosity in the pumice may be explained by a porous internal grain structure that allows storage of additional water. Mixtures with smectite are characterized by higher compressibility and higher porosity. For a mixture of 80% smectite and 20% pumice the porosity decreases from 65% to 39%, similar to that of the natural samples. Our results suggest that the high porosity zone is caused by the bulk mechanical behavior of pumice in the USB.

Astronomical forcing, insolation and millennial-scale climate variability: evidence from the North Atlantic Ocean (IODP Expedition 306, Site U1313) during the Early-Middle Pleistocene

NASA Astrophysics Data System (ADS)

Ferretti, Patrizia; Crowhurst, Simon; Naafs, David; Barbante, Carlo

2015-04-01

Since the seminal work by Hays, Imbrie and Shackleton (1976), a plethora of studies mostly based on marine sediments collected during DSDP-ODP-IODP Expeditions has demonstrated a correlation between orbital variations and climatic change. However, information on how changes in orbital boundary conditions affected the frequency and amplitude of millennial-scale climate variability is still fragmentary. Here we examine the record of climatic conditions from MIS 23 to 17 (c. 920-670 ka) using high-resolution stable isotope records from benthic and planktonic foraminifera from a sedimentary sequence in the North Atlantic (Integrated Ocean Drilling Program Expedition 306, Site U1313) in order to evaluate the climate system's response in the millennial band to known orbitally induced insolation changes. Special emphasis is placed on Marine Isotope Stage (MIS) 19, an interglacial centred at around 785 ka during which the insolation appears comparable to the current orbital geometry: MIS 19 is characterised by a minimum of the 400-kyr eccentricity cycle, subdued amplitude of precessional changes, and small amplitude variations in insolation making this marine isotopic stage a potential astronomical analogue for the Holocene and its future evolution, if this remains governed by natural forcing (Loutre and Berger 2000). Benthic and planktonic foraminiferal oxygen isotope values indicate relatively stable conditions during the peak warmth of MIS 19, but sea-surface and deep-water reconstructions start diverging during the transition towards the glacial MIS 18, when large, cold excursions disrupt the surface waters whereas low amplitude millennial scale fluctuations persist in the deep waters as recorded by the oxygen isotope signal (Ferretti et al., 2015). The glacial inception occurred at ˜779 ka, in agreement with an increased abundance of tetra-unsaturated alkenones, reflecting the influence of icebergs and associated meltwater pulses and high-latitude waters at the study site. Using a variety of time series analysis techniques, we evaluate the evolution of millennial climate variability in response to changing orbital boundary conditions during the early-middle Pleistocene. Suborbital variability in both surface- and deep-water records is mainly concentrated at a period of ˜11 kyr and, additionally, at ˜5.8 and ˜3.9 kyr in the deep ocean; these periods are equal to harmonics of precession band oscillations. The fact that the response at the 11 kyr period increased over the same interval during which the amplitude of the response to the precessional cycle increased supports the notion that most of the variance in the 11 kyr band in the sedimentary record is nonlinearly transferred from precession band oscillations. Considering that these periodicities are important features in the equatorial and intertropical insolation, these observations are in line with the view that the low-latitude regions play an important role in the response of the climate system to the astronomical forcing. We conclude that the effect of the orbitally induced insolation is of fundamental importance in regulating the timing and amplitude of millennial scale climate variability. Ferretti P., Crowhurst S.J., Naafs B.D.A., Barbante C., 2015. Quaternary Science Reviews 108, 95-110. Hays J.D., Imbrie J., Shackleton N.J., 1976. Science 194, 1121-1132. Loutre M.F., Berger A., 2000. Climatic Change 46, 61-90.

Extraordinary rocks from the peak ring of the Chicxulub impact crater: P-wave velocity, density, and porosity measurements from IODP/ICDP Expedition 364

NASA Astrophysics Data System (ADS)

Christeson, G. L.; Gulick, S. P. S.; Morgan, J. V.; Gebhardt, C.; Kring, D. A.; Le Ber, E.; Lofi, J.; Nixon, C.; Poelchau, M.; Rae, A. S. P.; Rebolledo-Vieyra, M.; Riller, U.; Schmitt, D. R.; Wittmann, A.; Bralower, T. J.; Chenot, E.; Claeys, P.; Cockell, C. S.; Coolen, M. J. L.; Ferrière, L.; Green, S.; Goto, K.; Jones, H.; Lowery, C. M.; Mellett, C.; Ocampo-Torres, R.; Perez-Cruz, L.; Pickersgill, A. E.; Rasmussen, C.; Sato, H.; Smit, J.; Tikoo, S. M.; Tomioka, N.; Urrutia-Fucugauchi, J.; Whalen, M. T.; Xiao, L.; Yamaguchi, K. E.

2018-08-01

Joint International Ocean Discovery Program and International Continental Scientific Drilling Program Expedition 364 drilled into the peak ring of the Chicxulub impact crater. We present P-wave velocity, density, and porosity measurements from Hole M0077A that reveal unusual physical properties of the peak-ring rocks. Across the boundary between post-impact sedimentary rock and suevite (impact melt-bearing breccia) we measure a sharp decrease in velocity and density, and an increase in porosity. Velocity, density, and porosity values for the suevite are 2900-3700 m/s, 2.06-2.37 g/cm3, and 20-35%, respectively. The thin (25 m) impact melt rock unit below the suevite has velocity measurements of 3650-4350 m/s, density measurements of 2.26-2.37 g/cm3, and porosity measurements of 19-22%. We associate the low velocity, low density, and high porosity of suevite and impact melt rock with rapid emplacement, hydrothermal alteration products, and observations of pore space, vugs, and vesicles. The uplifted granitic peak ring materials have values of 4000-4200 m/s, 2.39-2.44 g/cm3, and 8-13% for velocity, density, and porosity, respectively; these values differ significantly from typical unaltered granite which has higher velocity and density, and lower porosity. The majority of Hole M0077A peak-ring velocity, density, and porosity measurements indicate considerable rock damage, and are consistent with numerical model predictions for peak-ring formation where the lithologies present within the peak ring represent some of the most shocked and damaged rocks in an impact basin. We integrate our results with previous seismic datasets to map the suevite near the borehole. We map suevite below the Paleogene sedimentary rock in the annular trough, on the peak ring, and in the central basin, implying that, post impact, suevite covered the entire floor of the impact basin. Suevite thickness is 100-165 m on the top of the peak ring but 200 m in the central basin, suggesting that suevite flowed downslope from the collapsing central uplift during and after peak-ring formation, accumulating preferentially within the central basin.

Sedimentation in a Submarine Seamount Apron at Site U1431, International Ocean Discovery Program Expedition 349, South China Sea

NASA Astrophysics Data System (ADS)

Dadd, K. A.; Clift, P. D.; Hyun, S.; Jiang, T.; Liu, Z.

2014-12-01

International Ocean Discovery Program (IODP) Expedition 349 Site U1431 is located near the relict spreading ridge in the East Subbasin of the South China Sea. Holes at this site were drilled close to seamounts and intersected the volcaniclastic apron. Volcaniclastic breccia and sandstone at Site U1431 are dated as late middle Miocene to early late Miocene (~8-13 Ma), suggesting a 5 m.y. duration of seamount volcanism. The apron is approximately 200 m thick and is sandwiched between non-volcaniclastic units that represent the background sedimentation. These comprise dark greenish gray clay, silt, and nannofossil ooze interpreted as turbidite and hemipelagic deposits that accumulated at abyssal water depths. At its base, the seamount sequence begins with dark greenish gray sandstone, siltstone, and claystone in upward fining sequences interpreted as turbidites intercalated with minor intervals of volcaniclastic breccia. Upsection the number and thickness of breccia layers increases with some beds up to 4.8 m and possibly 14.5 m thick. The breccia is typically massive, ungraded, and poorly sorted with angular to subangular basaltic clasts, as well as minor reworked subrounded calcareous mudstone, mudstone, and sandstone clasts. Basaltic clasts include nonvesicular aphyric basalt, sparsely vesicular aphyric basalt, highly vesicular aphyric basalt, and nonvesicular glassy basalt. Mudstone clasts are clay rich and contain foraminifer fossils. The matrix comprises up to 40% of the breccia beds and is a mix of clay, finer grained altered basalt clasts, and mafic vitroclasts with rare foraminifer fossils. Some layers have calcite cement between clasts. Volcaniclastic sandstone and claystone cycles interbedded with the breccia layers have current ripples and parallel laminations indicative of high-energy flow conditions during sedimentation. The breccia beds were most likely deposited as a series of debris flows or grain flows. This interpretation is supported by their massive structure, poor sorting, and reverse-graded bases. The upper part of the apron grades back into the background clay, silt and nannofossil ooze sedimentation with minor volcaniclastic sand and silt.

Geochemistry of Volcanic Rocks from International Ocean Discovery Program (IODP) Site 1438, Amami Sankaku Basin: Implications for Izu-Bonin-Mariana (IBM) Arc Initiation

NASA Astrophysics Data System (ADS)

Hickey-Vargas, R.; Ishizuka, O.; Yogodzinski, G. M.; Bizimis, M.; Savov, I. P.; McCarthy, A. J.; Arculus, R. J.; Bogus, K.

2015-12-01

IODP Expedition 351 drilled 150 m of volcanic basement overlain by 1461 m of sedimentary material at Site 1438 in the Amami Sankaku basin, just west of the Kyushu Palau Ridge, the locus of IBM arc initiation. Age interpretations based on biostratigraphy (Arculus et al., Nat. Geosci., in-press) determined that the age of the basement section is between 64 and 51 Ma, encompassing the age of the earliest volcanic products of the IBM arc. The Site 1438 volcanic basement consists of multiple flows of aphyric microcrystalline to finely crystalline basalts containing plagioclase and clinopyroxene with rare olivine pseudomorphs. New XRF major and ICPMS trace element data confirm findings of shipboard analysis that the basalts are moderately differentiated (6-14 % MgO; Mg# = 51-83; 73-490 ppm Cr and 58-350 ppm Ni) with downcore variations related to flow units. Ti/V and Ti/Sc ratios are 16-27 and 75-152, respectively, with lowest values at the base of the core. One prominent characteristic of the basalts is their depletion of immobile highly incompatible elements compared with MORB. Basalts have MORB-normalized La/Nd of 0.5 to 0.9, and most have Th/La < 0.05. Although all basalts are LREE-depleted, La/Nd ratios increase slightly upcore, and Th enrichment compared with LREE occurs in the uppermost 5 meters. Cs, Rb, K, Ba and U are concomitantly enriched relative to LREE in several intervals as a probable result of seawater alteration, but ratios less than those of MORB are found in other areas. In contrast to basement, andesites from three sills in the lowermost sedimentary unit have arc-like trace element patterns with La/Nb > 3 and primitive mantle normalized La/Yb > 1. Our results suggest that mantle melting at the onset of subduction involved exceptionally depleted sources. Enrichment over time may be related to increasing subduction inputs and/or other processes, such as entrainment of fertile asthenosphere during extension of the overriding plate.

Late Pleistocene-Holocene phytoplankton productivity in the Gulf of Alaska, IODP Site U1419

NASA Astrophysics Data System (ADS)

LeVay, L. J.; Romero, O. E.; McClymont, E.; Müller, J.; Penkrot, M. L.; Jaeger, J. M.; Mix, A.; Walczak, M.

2016-12-01

The modern Gulf of Alaska (GoA) is a high-nutrient, low-chlorophyll region that is iron-limited; however, the coastal region of Alaska is macronutrient-limited. Vertical mixing of these shallow coastal and deep basinal waters produce high seasonal productivity across the shelf. Previous studies on the Alaskan shelf showed that productivity varied across the Pleistocene-Holocene transition, likely related to climate and sea level change that brought nutrients from estuaries into the Gulf. Here we explore an extended record through the Late Pleistocene-Holocene to reconstruct the productivity of phytoplankton groups in the GoA and to understand the impact of glacial/interglacial climates on primary production and nutrient availability near the shelf. International Ocean Discovery Program (IODP) Site U1419 was cored during Expedition 341 on the upper continental slope in the GoA. A high-resolution sedimentary sequence was recovered that records Late Pleistocene-Holocene glacial and paleoceanographic dynamics. Both calcareous nannoplankton and diatoms are well-represented at Site U1419. Very few studies have explored the competition of these two phytoplankton groups in the geologic record. Because calcareous nannoplankton and diatoms favor differing nutrient conditions, changes in their abundance can aid in reconstructing shifts in primary productivity as well as the causes, such as stratification or nutrient limitation. We present a multi-proxy record, including the group and species abundance of diatoms and calcareous nannoplankton, biogenic bulk components content, alkenone-based sea surface temperatures, and XRF core scanning elemental composition, which is used to interpret fluctuations in phytoplankton and identify the underlying causes. Initial results show the group abundance of nannoplankton and diatoms fluctuates greatly and appears to covary. Calcareous nannoplankton abundance increases with sea surface temperature and is related to higher alkenone concentrations in the sediments. The occurrence of diatoms is sporadic and could be linked to silica-limitation in surface waters. These findings will provide new insights into the processes governing fossil phytoplankton interactions and how this affects production and carbon cycling on the shelf.

Characterizing the Inner Accretionary Prism of the Nankai Trough with 3D Seismic and Logging While Drilling at IODP Site C0002

NASA Astrophysics Data System (ADS)

Boston, B.; Moore, G. F.; Jurado, M. J.; Sone, H.; Tobin, H. J.; Saffer, D. M.; Hirose, T.; Toczko, S.; Maeda, L.

2014-12-01

The deeper, inner parts of active accretionary prisms have been poorly studied due the lack of drilling data, low seismic image quality and typically thick overlying sediments. Our project focuses on the interior of the Nankai Trough inner accretionary prism using deep scientific drilling and a 3D seismic cube. International Ocean Discovery Program (IODP) Expedition 348 extended the existing riser hole to more than 3000 meters below seafloor (mbsf) at Site C0002. Logging while drilling (LWD) data included gamma ray, resistivity, resistivity image, and sonic logs. LWD analysis of the lower section revealed on the borehole images intense deformation characterized by steep bedding, faults and fractures. Bedding plane orientations were measured throughout, with minor gaps at heavily deformed zones disrupting the quality of the resistivity images. Bedding trends are predominantly steeply dipping (60-90°) to the NW. Interpretation of fractures and faults in the image log revealed the existence of different sets of fractures and faults and variable fracture density, remarkably high at fault zones. Gamma ray, resistivity and sonic logs indicated generally homogenous lithology interpretation along this section, consistent with the "silty-claystone" predominant lithologies described on cutting samples. Drops in sonic velocity were observed at the fault zones defined on borehole images. Seismic reflection interpretation of the deep faults in the inner prism is exceedingly difficult due to a strong seafloor multiple, high-angle bedding dips, and low frequency of the data. Structural reconstructions were employed to test whether folding of seismic horizons in the overlying forearc basin could be from an interpreted paleothrust within the inner prism. We used a trishear-based restoration to estimate fault slip on folded horizons landward of C0002. We estimate ~500 m of slip from a steeply dipping deep thrust within the last ~0.9 Ma. Folding is not found in the Kumano sediments near C0002, where normal faults and tilting dominate the modern basin deformation. Both logging and seismic are consistent in characterizing a heavily deformed inner prism. Most of this deformation must have occurred during or before formation of the overlying modern Kumano forearc basin sediments.

Late Eocene stable isotope stratigraphy of North Atlantic IODP Site U1411: Orbitally paced climatic heartbeat at the close of the Eocene greenhouse

NASA Astrophysics Data System (ADS)

Coxall, Helen; Bohaty, Steve; Wilson, Paul; Liebrand, Diederik; Nyberg, Anna; Holmström, Max

2016-04-01

Integrated Ocean Drilling Program (IODP) Expedition 342 drilled sediment drifts on the Newfoundland margin to recover high-resolution records of North Atlantic ocean-climate history and track the evolution of the modern climate system through the Late Cretaceous and Early Cenozoic. An early Paleogene deep-sea benthic stable isotope composite record from multiple Exp. 342 sites is currently in development and will provide a key reference section for investigations of Atlantic and global climate dynamics. This study presents initial results for the late Eocene slice of the composite from Site U1411, located at mid depth (˜2850m Eocene paleodepth) on the Southeast Newfoundland Ridge. Stable oxygen (δ18O) and carbon (δ13C) isotope ratios were measured on 640 samples hosting exceptionally well-preserved epifaunal benthic foraminifera obtained from the microfossil-rich uppermost Eocene clays at 4cm spacing. Sedimentation rates average 2-3 cm/kyr through the late Eocene, such that our sampling resolution is sufficient to capture the dominant Milankovitch frequencies. Late Eocene Site U1411 benthic δ18O values (1.4 to 0.5‰ VPDB) are comparable to the Pacific and elsewhere in the Atlantic at similar depths; however, δ13C is lower by ˜0.5 ‰ with values intermediate between those of the Southern Labrador Sea to the north (-1 to 0) and mid latitude/South Atlantic (0.5 to 1.5) to the south, suggesting poorly ventilated bottom waters in the late Eocene North Atlantic and limited production of North Atlantic deep water. Applying the initial shipboard magneto-biostratigraphic age framework, the Site U1411 benthic δ13C and δ18O records display clear cyclicity on orbital timescales. Spectral analysis of the raw unfiltered datasets identifies eccentricity (400 and 100 kyr), obliquity (40 kyr) and precession (˜20 kyr) signals imprinted on our time series, revealing distinct climatic heart beats in the late Eocene prior to the transition into the 'ice house'.

Mapping of rock types using a joint approach by combining the multivariate statistics, self-organizing map and Bayesian neural networks: an example from IODP 323 site

NASA Astrophysics Data System (ADS)

Karmakar, Mampi; Maiti, Saumen; Singh, Amrita; Ojha, Maheswar; Maity, Bhabani Sankar

2017-07-01

Modeling and classification of the subsurface lithology is very important to understand the evolution of the earth system. However, precise classification and mapping of lithology using a single framework are difficult due to the complexity and the nonlinearity of the problem driven by limited core sample information. Here, we implement a joint approach by combining the unsupervised and the supervised methods in a single framework for better classification and mapping of rock types. In the unsupervised method, we use the principal component analysis (PCA), K-means cluster analysis (K-means), dendrogram analysis, Fuzzy C-means (FCM) cluster analysis and self-organizing map (SOM). In the supervised method, we use the Bayesian neural networks (BNN) optimized by the Hybrid Monte Carlo (HMC) (BNN-HMC) and the scaled conjugate gradient (SCG) (BNN-SCG) techniques. We use P-wave velocity, density, neutron porosity, resistivity and gamma ray logs of the well U1343E of the Integrated Ocean Drilling Program (IODP) Expedition 323 in the Bering Sea slope region. While the SOM algorithm allows us to visualize the clustering results in spatial domain, the combined classification schemes (supervised and unsupervised) uncover the different patterns of lithology such of as clayey-silt, diatom-silt and silty-clay from an un-cored section of the drilled hole. In addition, the BNN approach is capable of estimating uncertainty in the predictive modeling of three types of rocks over the entire lithology section at site U1343. Alternate succession of clayey-silt, diatom-silt and silty-clay may be representative of crustal inhomogeneity in general and thus could be a basis for detail study related to the productivity of methane gas in the oceans worldwide. Moreover, at the 530 m depth down below seafloor (DSF), the transition from Pliocene to Pleistocene could be linked to lithological alternation between the clayey-silt and the diatom-silt. The present results could provide the basis for the detailed study to get deeper insight into the Bering Sea' sediment deposition and sequence.

The Role of Microfossils in the Compression of Marine Sediments: Implications for Submarine Slope Failure

NASA Astrophysics Data System (ADS)

Reece, J. S.; Shackleton, T.

2016-12-01

The influence of microfossils on engineering properties has long been recognized. However, most experimental studies have been conducted on diatomites, which are almost exclusively composed of diatom fossils. Here, instead, we analyze the impact of varying amounts of microfossils in natural marine sediments on the macro-scale mechanical behavior. We use foraminifera as an example for microfossils, which, in contrast to diatoms, have been understudied. We uniformly mix foraminifera with natural mudstone from Site C0011 in the Nankai Trough, offshore Japan, obtained during Integrated Ocean Drilling Program (IODP) Expedition 322, at three different microfossil concentrations: 0 wt%, 5 wt%, and 10 wt%. The foraminifera, extracted by washing and sieving, originated from IODP Site U1338 in the Equatorial Pacific. We use resedimentation to prepare the homogeneous microfossil-rich mudstone samples and uniaxially compress them to 100 kPa. Additionally, we use scanning electron microscopy to investigate microstructural changes during compression as a function of microfossil content. Microfossil-rich sediments are known to initially not consolidate to as low porosities as other marine clays owing to microfossil shells acting as structural components. But they show a delayed compressibility when the yield stress is overcome and microfossil shells collapse resulting in an increase in porosity and compressibility. Here, we investigate the 1) threshold microfossil content at which the microfabric significantly changes during compression and 2) stress at which foraminifera chambers start to break. We anticipate to observe an increase in compressibility and microstructural changes in the vicinity of the yield stress with increasing microfossil content attributed to the crushing of foraminifera and particle rearrangement. But the total axial stress of 100 kPa at the end of the resedimentation experiments may not be large enough to have a significant effect on the macroscopic mudstone properties. This study has large implications for submarine slope failure due to the possible sudden expulsion of water causing a pore pressure increase, which may destabilize continental slopes, and cause a hazard for coastal communities and offshore infrastructure.

38 CFR 3.161 - Expedited Claims Adjudication Initiative-Pilot Program.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Adjudication Initiative-Pilot Program. 3.161 Section 3.161 Pensions, Bonuses, and Veterans' Relief DEPARTMENT... Claims § 3.161 Expedited Claims Adjudication Initiative—Pilot Program. Rules pertaining to the Expedited Claims Adjudication Initiative Pilot Program are set forth in part 20, subpart P, of this chapter...

Possible large-volume mafic explosive eruptions in the Izu arc recorded in IODP Site U1436

NASA Astrophysics Data System (ADS)

Tamura, Y.; Jutzeler, M.; Schindlbeck, J. C.; Nichols, A. R.; DeBari, S.; Gill, J.; Busby, C. J.; Blum, P.

2014-12-01

The Izu-Bonin-Mariana volcanic arc system is an excellent example of an intraoceanic convergent margin where the effects of crustal anatexis and assimilation are considered to be minimal. The Izu fore arc is a repository of ashes erupted in the Izu-Bonin frontal arc because the prevailing wind blows from west to east. IODP Site U1436 (proposed Site IBM-4GT), located at 32°23.88'N, 140°21.93'E, lies in the western part of the Izu fore arc basin, ~60 km east of the arc-front volcano Aogashima, ~170 km west of the axis of the Izu-Bonin Trench, 1.5 km west of ODP Site 792, and at 1776 mbsl. It was drilled in April-May 2014, during IODP Expedition 350, as a 150 m deep geotechnical test hole for potential future deep drilling at proposed Site IBM-4 using the D/V Chikyu. The stratigraphic record of Late Pleistocene mafic and silicic explosive volcanic products from the arc front consists of tuffaceous mud interstratified with mafic and evolved ash and lapilli, including distinctive black glassy mafic ash layers. These distinctive intervals are basaltic andesite and the most mafic deposits analyzed shipboard at Site U1436. The facies appeared to be unusually homogeneous in componentry and texture; the overwhelmingly glassy nature of the ash suggests subaqueous explosive eruption, and its good sorting suggests deposition by vertical settling through the water column from an ash plume that reached the atmosphere. An alterative hypothesis is that the ash layers have been redeposited in bathymetric lows by submarine density currents. These black glassy mafic ash layers attracted a great deal of interest among the science party because, if the first hypothesis is correct, they could record large-volume mafic explosive eruptions. As a result three more holes were drilled at Site U1436, in order to recover undisturbed examples of these layers. Samples from each hole are currently undergoing post-cruise geochemical (major, traces and volatiles) and componentry analysis to test these two hypotheses in more detail.

Palaeointensity determinations and rock magnetic properties on basalts from Shatsky Rise: new evidence for a Mesozoic dipole low

NASA Astrophysics Data System (ADS)

Carvallo, C.; Camps, P.; Ooga, M.; Fanjat, G.; Sager, W. W.

2013-03-01

IODP Expedition 324 cored igneous rocks from Shatsky Rise, an oceanic plateau in the northwest Pacific Ocean that formed mainly during late Jurassic and Early Cretaceous times. We selected 60 samples from 3 different holes for Thellier-Thellier palaeointensity determinations. Induced and remanent magnetization curves measured at low- and high-temperature suggest a diverse and complex magnetic mineralogy, with large variations in Ti content and oxidation state. Hysteresis and FORC measurements show that most samples contain single-domain magnetic grains. After carrying out the palaeointensity determinations, only 9 samples satisfied all reliability criteria. These gave palaeointensity values between 16.5 and 21.5 μT, which correspond to average VDM values of (4.9 ± 0.2) × 1022 Am2 for an estimated age of 140-142 Ma. This value is lower than that for the recent field, which agrees with the hypothesis of a Mesozoic Dipole Low.

Video at Sea: Telling the Stories of the International Ocean Discovery Program

NASA Astrophysics Data System (ADS)

Wright, M.; Harned, D.

2014-12-01

Seagoing science expeditions offer an ideal opportunity for storytelling. While many disciplines involve fieldwork, few offer the adventure of spending two months at sea on a vessel hundreds of miles from shore with several dozen strangers from all over the world. As a medium, video is nearly ideal for telling these stories; it can capture the thrill of discovery, the agony of disappointment, the everyday details of life at sea, and everything in between. At the International Ocean Discovery Program (IODP, formerly the Integrated Ocean Drilling Program), we have used video as a storytelling medium for several years with great success. Over this timeframe, camera equipment and editing software have become cheaper and easier to use, while web sites such as YouTube and Vimeo have enabled sharing with just a few mouse clicks. When it comes to telling science stories with video, the barriers to entry have never been lower. As such, we have experimented with many different approaches and a wide range of styles. On one end of the spectrum, live "ship-to-shore" broadcasts with school groups - conducted with an iPad and free videoconferencing software such as Skype and Zoom - enable curious minds to engage directly with scientists in real-time. We have also contracted with professional videographers and animators who offer the experience, skill, and equipment needed to produce polished clips of the highest caliber. Amateur videographers (including some scientists looking to make use of their free time on board) have shot and produced impressive shorts using little more than a phone camera. In this talk, I will provide a brief overview of our efforts to connect with the public using video, including a look at how effective certain tactics are for connecting to specific audiences.

Making Real Life Connections and Engaging High School Students as They Become Climate Detectives using data obtained through JOIDES Resolution Expedition 341

NASA Astrophysics Data System (ADS)

Chegwidden, D.; Mote, A. S.; Manley, J.; Ledley, T. S.; Haddad, N.; Ellins, K.; Lynds, S. E.

2016-02-01

Texas is a state that values and supports an Earth Science curriculum, and as an experienced educator in Texas, I find it crucial to educate my students about the various Ocean Science careers that exist and also be able to use the valuable data that is obtained in a core sample from the ocean floor. "Climate Detective" is an EarthLabs module that is supported by TERC and International Ocean Discovery Program (IODP) Expedition 341. This module contains hands-on activities, many opportunities to interpret actual data from a core sample, and collaborative team skills to solve a problem. Through the module, students are able to make real connections with scientists when they understand various roles aboard the JOIDES Resolution. Students can also visually experience real-time research via live video streaming within the research vessel. In my classroom, the use of the "Climate Detective" not only establishes a beneficial relationship between teacher and marine scientists, but such access to the data also helps enhance the climate-related concepts and explanatory procedures involved in obtaining reports. Data is applied to a challenge question for all student groups to answer at the end of the module. This Project-based learning module emphasizes different forms of evidence and requires that learners apply different inquiry approaches to build the knowledge each one needs to acquire, as they become climate-literate citizens. My involvement with the EarthLabs project has strengthened my overall knowledge and confidence to teach about Earth's systems and climate change. In addition, this experience has led me to become an advocate who promotes vigorous classroom discussion among my students; additionally, I am encouraged to collaborate with other educators through the delivery of professional development across the state of Texas. Regularly, I connect with scientists in my classroom and such connection truly enriches not only my personal knowledge, but also provides a foundational understanding for my students.

Reconstructing Oceanographic Conditions From the Holocene to the Last Glacial Maximum in the Bay of Bengal

NASA Astrophysics Data System (ADS)

Miller, J.; Dekens, P. S.; Weber, M. E.; Spiess, V.; France-Lanord, C.

2015-12-01

The International Ocean Discovery Program (IODP) Expedition 354 drilled 7 sites in the Bay of Bengal, providing a unique opportunity to improve our understanding of the link between glacial cycles, tropical oceanographic changes, and monsoon strength. Deep-sea sediment cores of the Bengal Fan fluctuate between sand, hemipelagic and terrestrial sediment layers. All but one of the sites (U1454) contain a layer of calcareous clay in the uppermost part of the core that is late Pleistocene in age. During Expedition 354 site U1452C was sampled at high resolution (every 2cm) by a broad group of collaborators with the goal of reconstructing monsoon strength and oceanographic conditions using a variety of proxies. The top 480 cm of site U1452C (8ºN, 87ºE, 3671m water depth) contains primarily nannofossil rich calcareous clay. The relatively high abundance of foraminifera will allow us to generate a high resolution record of sea surface temperature (SST) and sea surface salinity (SSS) using standard foraminifera proxies. We will present oxygen isotopes (δ18O) and Mg/Ca data of mixed layer planktonic foraminifera from the top 70cm of the core, representing the Holocene to the last glacial maximum. δ18O of planktonic foraminifera records global ice volume and local SST and SSS, while Mg/Ca of foraminifera is a proxy for SST. The paired Mg/Ca and δ18O measurements on the same samples of foraminifera, together with published estimates with global ocean δ18O, can be used to reconstruct both SST and local δ18O of seawater, which is a function of the evaporation/precipitation balance. In future work, the local SSS and SST during the LGM will be paired with terrestrial and other oceanic proxies to increase our understanding of how global climate is connected to monsoon strength.

Benthic Biotic Response to Climate Changes over the Last 700,000 Years, the Sea of Japan: Ostracode Assemblages from Site U1427, IODP Expedition 346

NASA Astrophysics Data System (ADS)

Huang, H. H. M.; Yasuhara, M.; Iwatani, H.; Alvarez Zarikian, C. A.; Bassetti, M. A.; Sagawa, T.

2016-12-01

The Sea of Japan is a marginal sea, semi-enclosed by the Eurasian Continent, Korean Peninsula, Japanese Islands, and shallow straits (water depth < 130 m). Marginal seas are ideal natural laboratories to study biotic responses to large-scale paleoclimate-ocean mechanisms as they are typically sensitive to glacial/interglacial and stadial/interstadial cycles. The modern oceanographic setting in the Sea of Japan is characterized by the influx of the Tsushima Warm Current (TWC) from the East China Sea, and this setting was formed 1.7 My ago by tectonic subsidence of the Tsushima Strait. The Sea of Japan, therefore, is an interesting research subject for studying the biotic response to orbital-scale climate changes and benthic faunal development under the influence of TWC. Here we present 700,000-year record of benthic biotic response to the paleoceanographic changes in the southern Sea of Japan based on ostracode assemblage reconstruction at IODP Site U1427. Five local extinction events were caused by extreme bottom conditions (mainly oxygen depletion) during the Ice Age Terminations I, II, IV, V, and VII. Primary and secondary ostracode assemblages were revealed by Q-mode k-means clustering, CABFAC factor analysis, and non-metric multidimensional scaling. The primary ostracode components, characterized by Krithe sawanensis and Cytheropteron hyalinosa, broadly reflect glacial/interglacial and high-latitude insolation cycles. In contrast, a faunal shift determined by the secondary faunal components was driven by the TWC enhancement at 300 ka.

Rapid Shifts in Oxygen and Hydrogen Isotopes, and Chemical Components in Pore Waters During mid-Oligocene in Sediments from IODP 351drilling

NASA Astrophysics Data System (ADS)

Zhang, Z.

2017-12-01

A total of 65 pore water samples were obtained from a sediment sequence in the Amami-Sankaku Basin during the IODP 351 Expedition, which consists of a 160 m thick section of terrestrial origin and underlying 1.3 km thick volcaniclastic section sampled at site U1438. Downcore variations of chemical compositions are characterized by increasing salinity/pH, increasing concentrations of Cl and Ca, and decreasing concentrations of Mg, K and Na, as well as decreasing d18O and dD. The rapid changes in those chemical components and isotopic composition occurred deeper than the lithology boundary between Unit III and Unit II, most likely as a result of substantial difference in extent of alteration above and below this boundary. The strong alterations of volcanicalstic minerals below the boundary not only result in diminishment of K, Mg, Si, and Mn, and an increase of Ca and Cl, but also depleted d18O in pore water. However, hydrogen fractionation factors between pore water and secondary minerals are less 1, and depleted dD values in pore water most likely reflect the signal of paleo-seawater. As a result, samples below the boundary are all plotted on the left side of the meteorite water line (MWL) on the dD vs. d18O plot. Above the boundary, they are placed to the right side of MWL due to substantially weakened alteration, reflecting an evolving trend in sediment setting from the predominance of alterated volcaniclasts to terrestrial pelagic sediments.

Integrated tephrostratigraphy and stable isotope stratigraphy in the Japan Sea and East China Sea using IODP Sites U1426, U1427, and U1429, Expedition 346 Asian Monsoon

NASA Astrophysics Data System (ADS)

Sagawa, Takuya; Nagahashi, Yoshitaka; Satoguchi, Yasufumi; Holbourn, Ann; Itaki, Takuya; Gallagher, Stephen J.; Saavedra-Pellitero, Mariem; Ikehara, Ken; Irino, Tomohisa; Tada, Ryuji

2018-12-01

Integrated Ocean Drilling Program Expedition 346 "Asian Monsoon" obtained sediment successions at seven sites in the Japan Sea (Sites U1422-U1427 and U1430) and at two closely located sites in the northern East China Sea (Sites U1428 and U1429). The Quaternary sediments of the Japan Sea are characterized by centimeter- to decimeter-scale dark-light alternations at all sites deeper than 500 m water depth. The sedimentary records from these sites allow an investigation of the regional environmental response to global climate change, including changes in the Asian Monsoon and eustatic sea level. However, the discontinuous occurrence of calcareous microfossils in the deep-sea sediments and their distinct isotope signature that deviates from standard marine δ18O records do not permit the development of a detailed stable isotope stratigraphy for Japan Sea sediments. Here, we present the tephrostratigraphy for the two southernmost sites drilled in the Japan Sea (Sites U1426 and U1427) and for one site drilled in the East China Sea (Site U1429) along with the benthic δ18O isotope stratigraphy for the shallower Site U1427 and the East China Sea Site U1429. Eighteen tephra layers can be correlated between sites using the major-element composition and morphology of volcanic glass shards, and the compositions of grains and heavy minerals. Tephra correlations show that negative δ18O peaks in the Japan Sea correspond to positive glacial maxima peaks in the East China Sea. Using this integrated stratigraphic approach, we establish an orbital-scale age model at Site U1427 for the past 1.1 Myr. The correlation of tephra layers between the shallower Site U1427 (330 m below sea level: mbsl) and the deeper Site U1426 (903 mbsl) in the southern Japan Sea provides the opportunity for further age constraints. Our results show that alternations in sediment color at Sites U1426 and U1427 can be correlated for the past 1.1 Myr with minor exceptions. Thus, the stable isotope stratigraphy established at the shallower Site U1427 can be correlated to Site U1426, and in turn to all sites drilled during Expedition 346, based on correlations of dark-light layering.

Physical properties and seismic structure of Izu-Bonin-Mariana fore-arc crust: Results from IODP Expedition 352 and comparison with oceanic crust

NASA Astrophysics Data System (ADS)

Christeson, G. L.; Morgan, S.; Kodaira, S.; Yamashita, M.; Almeev, R. R.; Michibayashi, K.; Sakuyama, T.; Ferré, E. C.; Kurz, W.

2016-12-01

Most of the well-preserved ophiolite complexes are believed to form in suprasubduction zone (SSZ) settings. We compare physical properties and seismic structure of SSZ crust at the Izu-Bonin-Mariana (IBM) fore arc with oceanic crust drilled at Holes 504B and 1256D to evaluate the similarities of SSZ and oceanic crust. Expedition 352 basement consists of fore-arc basalt (FAB) and boninite lavas and dikes. P-wave sonic log velocities are substantially lower for the IBM fore arc (mean values 3.1-3.4 km/s) compared to Holes 504B and 1256D (mean values 5.0-5.2 km/s) at depths of 0-300 m below the sediment-basement interface. For similar porosities, lower P-wave sonic log velocities are observed at the IBM fore arc than at Holes 504B and 1256D. We use a theoretical asperity compression model to calculate the fractional area of asperity contact Af across cracks. Af values are 0.021-0.025 at the IBM fore arc and 0.074-0.080 at Holes 504B and 1256D for similar depth intervals (0-300 m within basement). The Af values indicate more open (but not necessarily wider) cracks in the IBM fore arc than for the oceanic crust at Holes 504B and 1256D, which is consistent with observations of fracturing and alteration at the Expedition 352 sites. Seismic refraction data constrain a crustal thickness of 10-15 km along the IBM fore arc. Implications and inferences are that crust-composing ophiolites formed at SSZ settings could be thick and modified after accretion, and these processes should be considered when using ophiolites as an analog for oceanic crust.

Reconstructing paleoceanographic conditions during the Oligocene/Miocene Boundary using walled dinoflagellate cysts and TEX86: IODP Expedition 318, Wilkes Land, Antarctic margin

NASA Astrophysics Data System (ADS)

Bijl, Peter; Bruls, Anja; Hartman, Julian D.; Sangiorgi, Francesca; Peterse, Francien

2017-04-01

Wilkes land is potentially a sensitive sector of the East Antarctic Ice Sheet (EAIS), because Wilkes subglacial basin is largely below sea level. In light of this, understanding changes in ice volume in this sector of Antarctica during past episodes of warmth may help constrain future ice sheet melt in the region. Integrated Ocean Drilling Program Expedition 318 was intended to drill and recover from the Wilkes Land continental Margin to reconstruct the history of the East Antarctic ice sheet (EAIS). The integrated bio-magnetostratigraphic age model for IODP Site U1356 is quite robust for the entire stratigraphic record, but in the Oligocene-Miocene boundary interval, the details of the age model are somewhat elusive. Notably it is uncertain whether sediments dating back to the Mi-1 glaciation event, at the Oligocene-Miocene boundary, are represented in the record. This research presents a revised age model for the interval around the OMT and gives a paleoceanographic interpretation of Site U1356 based on dinocyst ecology and TEX86 biomarker proxy. The finding of the dinocyst species Edwardsiella sexispinosa provides for an additional dinocyst event, and revised the location of the OMT. Core 45R likely represents the base of the Miocene and Core 46R and Core 47R represents the late Oligocene between 23.23 to 25.1 Ma. The dinocyst ecology indicated varying intervals of mostly Protoperidinioid genera to mostly Gonyaulacoid genera, that represent high productivity conditions and oligotrophic conditions respectively. These changing ecological conditions have been related to the a changing upwelling regime along the Wilkes Land margin, which is connected to the polar wind field and positively correlated to the extent of the Antarctic ice sheets. Sea ice conditions are absent along the Wilkes Land margin throughout this part of the record, therefore deep-water formation would also have been reduced. The SST record provided by TEX86 biomarker proxy indicates a decreasing trend towards the Miocene, but does not seem to point consistently to a warmer climate state during the late Oligocene. The dinocyst and TEX86 records seem to infer a smaller than present, dynamic Antarctic ice sheet during the late Oligocene to early Miocene, yet in combination with a quite invariant state of the atmospheric pCO2 record (Zhang et al., 2013). This seems to indicate a more sensitive Antarctic ice sheet possibly related to a threshold size for a stable ice sheet. However the ice volume changes inferred from the global benthic foraminiferal δ18O record could also have been of a smaller extent. Another cause that could potentially add to the changing δ18O record, is a change in deep water source, more specifically an alternating Southern Ocean deep-water formation which is coupled to the alternating Antarctic cryosphere.

Sulfur and iron geochemistry of the dynamic sedimentary system at the Costa Rica margin, IODP Expedition 344

NASA Astrophysics Data System (ADS)

Gott, C.; Riedinger, N.; Formolo, M.; Solomon, E. A.; Torres, M. E.; Bates, S. M.; Lyons, T. W.; 344 Scientific Party, I.

2013-12-01

One of the major targets of the CRISP (Costa Rica Seismogenesis Project) was to explore diagenetic processes, including fluid flow, related to the complex sedimentary and tectonic behavior of the Costa Rica margin system. Here we present preliminary results of the iron and sulfur geochemistry from sediments collected during the IODP Expedition 344 at Holes U1413B and U1414A. Our specific goal was to investigate the impact of this dynamic system on biogeochemical processes - especially regarding the sulfur cycle - and how minerals record these processes in the geologic record. The sediments at both investigated locations display non-steady state pore water conditions. Specifically, the deposits at Hole U1413B are characterized by a shallow sulfate-methane transition zone (SMTZ; approximately 15 mbsf), where released hydrogen sulfide reacts with reactive iron minerals to form iron sulfides. At Hole U1414A pore water sulfate is present at several hundreds of meters sediment depth, while the concentration of hydrogen sulfide is low (<4 μM). The measured concentrations of solid phase iron sulfides in the sediments indicate that pyrite is the main sulfur-bearing phase, reaching concentrations of 2 and 3 wt.%, in U1413B and U1414A, respectively. Sequential extractions of iron oxides reveal the presence of reactive iron phases, although in low concentrations (total iron oxides are below 1.1 wt.%), indicating ongoing alteration of iron oxides. The occurrence of these reactive iron minerals in the deeply buried sediments at Hole U1414A has implications for the deep biosphere - as those minerals can still be utilized by the microbial community. The non-steady state condition of the sedimentary system at both locations is also mirrored in the S-isotopic signal in the pore fluids as well as solid phase. The 34S-enriched sulfate (δ34S >+60 ‰) in the deeper sediment column is reflected in the δ34S profile of the in situ formed iron sulfides - the results can have implications for the interpretation of ancient rocks from similar active systems throughout Earth's history. Comparing the results of the investigated sediments at both sites, our data show variability, which may be caused by different sulfur sources and biogeochemical sulfur cycling driven by the tectonic and sedimentary complexity of the Costa Rica margin system.

Deep-sea trace fossil and benthic foraminiferal assemblages across glacial Terminations 1, 2 and 4 at the "Shackleton Site" (IODP Expedition 339, Site U1385)

NASA Astrophysics Data System (ADS)

Rodríguez-Tovar, Francisco J.; Dorador, Javier; Grunert, Patrick; Hodell, David

2015-10-01

Numerous studies focused on the transitions between glacial and interglacial periods, the so-called terminations, due to the associated significant reorganizations of the ocean-atmosphere system. However, analyses combining macro- and micropaleontological information are near absent. In this research, an integrative study of trace fossils and benthic foraminiferal assemblages is conducted in order to improve the characterization of Terminations 1, 2 and 4, as revealing the response of the macro-and microbenthic habitats to the involved paleoenvironmental changes. For this purpose, selected cores from Site U1385 (IODP Expedition 339) located off the western Iberian Margin, have been studied. Changes in trace fossils and benthic foraminifera related to both long-term variations at the glacial/interglacial scale, and short-term millennial-scale climatic events. Food and oxygen availability have been identified as the main factors determining variations in the macro- and microbenthic community structure across glacial terminations in the context of changes in water mass distribution and productivity in the NE Atlantic. A deep-sea multi-tiered tracemaker community, consisting of biodeformational structures, Chondrites, ?Nereites, Palaeophycus, Planolites, Thalassinoides, and Zoophycos, suggest generally well-oxygenated bottom and pore-water conditions during interglacial as well as glacial intervals, with punctual decreases in oxygenation. Short-climatic events registered during Terminations 1, 2, and 4 induce a similar response of trace fossil and benthic foraminifera communities to the variable incidence of food and oxygen availability. Termination 1 shows a severe deterioration of oxic conditions and increasing food availability during the YD and HS 1, favoring appearance/dominance of Zoophycos, together with the lowest miliolid and the highest deep infaunal taxa abundances. Short-term climatic events (HS 11, IRE 10.1) associated with Terminations 2 and 4 are characterized by a major incidence of export productivity and accumulation of organic matter respect to depletion oxygenation, especially affecting the microbenthic habitat. Dark sediment intervals of HS 11 and IRE 10.1 are characterized by higher abundances of Zoophycos, together with strong peaks in hBFAR values, significant lows in miliolids and lower abundance of deep infaunal taxa. The presence of Chondrites during IRE 10.1 also indicates the impoverishment in pore-water conditions deep within the sediment.

The Mechanics of Peak-Ring Impact Crater Formation from the IODP-ICDP Expedition 364

NASA Astrophysics Data System (ADS)

Melosh, H.; Collins, G. S.; Morgan, J. V.; Gulick, S. P. S.

2017-12-01

The Chicxulub impact crater is one of very few peak-ring impact craters on Earth. While small (less than 3 km on Earth) impact craters are typically bowl-shaped, larger craters exhibit central peaks, which in still larger (more than about 100 km on Earth) craters expand into mountainous rings with diameters close to half that of the crater rim. The origin of these peak rings has been contentious: Such craters are far too large to create in laboratory experiments and remote sensing of extraterrestrial examples has not clarified the mechanics of their formation. Two principal models of peak ring formation are currently in vogue, the "nested crater" model, in which the peak ring originates at shallow depths in the target, and the "dynamic collapse" model in which the peak ring is uplifted at the base of a collapsing, over-steepened central peak and its rocks originate at mid-crustal depths. IODP-ICDP Expedition 364 sought to elucidate, among other important goals, the mechanics of peak ring formation in the young (66 Myr), fresh, but completely buried Chicxulub impact crater. The cores from this borehole now show unambiguously that the rocks in the Chicxulub peak ring originated at mid-crustal depths, apparently ruling out the nested crater model. These rocks were shocked to pressures on the order of 10-35 GPa and were so shattered that their densities and seismic velocities now resemble those of sedimentary rocks. The morphology of the final crater, its structure as revealed in previous seismic imaging, and the results from the cores are completely consistent with modern numerical models of impact crater excavation and collapse that incorporate a model for post-impact weakening. Subsequent to the opening of a ca. 100 km diameter and 30 km deep transient crater, this enormous hole in the crust collapsed over a period of about 10 minutes. Collapse was enabled by movement of the underlying rocks, which briefly behaved in the manner of a high-viscosity fluid, a brittle deformation state described by the process of "acoustic" fluidization initiated by strong elastic vibrations accompanying the opening and collapse of the crater. The shattered core, cut by both melt rock and clastic dikes, is consistent with the block model of acoustic fluidization supporting its application to crater collapse both on the Earth and on other planets.

Oligocene-Miocene Transition in the North Atlantic Interrupted by Warming: New Records from the Newfoundland Margin, IODP Expedition 342

NASA Astrophysics Data System (ADS)

Smith, R.; Liebrand, D.; van Peer, T. E.; Bohaty, S. M.; Friedrich, O.; Bornemann, A.; Blum, P.; Wilson, P. A.

2016-12-01

The beginning and end of the Oligocene epoch were marked by major Antarctic glaciation events. While the Eocene-Oligocene transition is known to have initiated sustained major ice sheets on Antarctica, the intensification of glaciation associated with the Oligocene-Miocene Transition (OMT) 23 Ma appears to have been ephemeral. The inference of rapid growth and then retreat of large Antarctic ice sheets on orbital time scales is difficult to reconcile with the strong hysteresis seen in the results of numerical ice sheet model experiments and the modest variability seen in published records of atmospheric CO2. A number of benthic foraminiferal proxy records have been generated at orbital resolution across the OMT, but high-resolution sea-surface records are sparse, particularly in the mid to high latitudes of the northern hemisphere, with none yet produced in the Atlantic Ocean. IODP Site 1406 (40°N, 3799 m water depth, Expedition 342: Newfoundland Sediment Drifts) recovered an interval spanning the OMT in the North Atlantic. We present planktic foraminiferal stable isotope data from this interval (23.5-22.5 Ma) with an average sample spacing of 2 kyrs. Our high-fidelity sea surface record benefits from exceptional `glassy' preservation of clay-hosted foraminifera. Variability in our record shows prominent 100 kyr eccentricity pacing (cycle amplitude typically >1.0 ‰ in δ18O and >0.6‰ in δ13C) and a strong precessional influence. Intriguingly, while the rise in δ18O associated with the OMT is fairly smooth in benthic records, our planktic data show that after over two-thirds of the total 1.6‰ rise in δ18O had already taken place, a 50 kyr recovery to pre-OMT δ18O values occured, preceeding a rapid transition to the OMT δ18O maximum. Our results demonstrate for the first time the North Atlantic sea surface response to OMT events. The structure in our new planktic stable isotope record differs markedly from that seen in published benthic records. Interruption of the OMT δ18O excursion in our record implies that during initial Antarctic glaciation across the OMT, North Atlantic surface waters underwent a dramatic temporary warming.

On the Serpentinization Degree (S) of IODP Expedition 357 Atlantis Massif Rocks: Insights from Rock Magnetic Properties and Microscopic Magnetic Mineralogy Study of six Sites

NASA Astrophysics Data System (ADS)

Herrero-Bervera, E.; Whattam, S. A.; Frederichs, T.

2016-12-01

We have studied the magnetic properties of 37 serpentinized samples recovered via drilling during IODP Expedition 357, Atlantis Massif. We have recovered various lithologies including ultamafic rocks (primarily extensively serpentinized), subordidate gabbros, dolerites (small-scale melt injections) and schists. We have conducted remanence and induced magnetic experiments on the samples to determine for instance the degree of serpentinization (S). Stepwise alternating field and thermal demagnetization experiments from 2.5 to 70 mT and from 28 to 700°C, respectively, yielded univectorial diagrams showing the removal of secondary components (e.g., VRM, IRM, CRM) by isolating a characteristic component (ChRM) at various fields and temperatures. The normalized intensity of demagnetization (J/Jo) shows that the decrease of the magnetization of the specimens where about 50% of the original magnetization and is lost at about 5 mT and 100°C (i.e., Median Destructive Field). The stereograms show magnetic stability of the specimens by determining the directional behavior after 4 demagnetization steps (from 7.5-10 mT fields and low temperatures). Induced magnetization such as SIRM's, hysteresis saturation loops, back-fields and FORC experiments were performed. Diagnostic values of Mrs/Ms and Brc/Bc determine the domain structure of a magnetic sample. The magnetic grain sizes were determined using the protocol of Dunlop [2000]. Most of the samples were distributed over the Single (SD), Pseudo-Single Domain (PSD) and a few over the Multi Domain (MD) ranges with a certain degree of clustering on the PSD range. Curie points were obtained by measuring their low-field susceptibility vs. temperature from 28°C up to 700°C in an Argon atmosphere showing a minimum of 1-4 magnetic mineral phases with temperatures ranging from 100°C up to 640°C. These phases are predominantly Ti-poor, Ti-rich magnetite, maghemite and magnetite as corroborated by microscopic analysis as well as the Verwey transition (Tv≈110-120K). Samples studied show appreciable variation in bulk susceptibility (77.8 x 10-3 to 0.31 x 10-3 SI units). The samples are characterized by low, intermediate and high degree of serpentinization based on the results of their magnetic properties (e,g, Kappa, density, magnetic stability and Mrs/Ms vs Bcr/Bc).

Distribution of microbial methanogenesis, methane oxidation, and sulfate reduction in a high-temperature subduction system of the Nankai Trough off Cape Muroto (IODP Expedition 370 T-Limit, Site C0023)

NASA Astrophysics Data System (ADS)

Treude, T.; Kallmeyer, J.; Beulig, F.; Glombitza, C.; Schubert, F.; Krause, S.; Heuer, V.; Inagaki, F.; Morono, Y.

2017-12-01

The aim of the IODP Expedition 370 is to explore the temperature limit of the deep biosphere in a sub-seafloor environment located in the Nankai Trough, where in-situ sediment temperature increases from 2°C at the seafloor to about 120°C at the 1.2 km deep sediment/basement interface. Our study focuses on the exploration of potential microbial methanogenesis, anaerobic oxidation of methane (AOM), and sulfate reduction in sediments from different depths (from ca. 200 to 1170 mbsf) exposed to several temperature settings in the laboratory (40, 60, 75/80 and 95°C). The drill site, which features a décollement between ca. 758-796 mbsf, includes a sulfate-poor methanogenic zone from approx. 400 to 600 mbsf, followed by a deep methane-sulfate transition zone between approx. 600 to 800 m, which transitions into a deep sulfate-rich zone. Potential microbial activity of hydrogenotrophic methanogenesis, AOM, and sulfate reduction was determined in incubations of sediment slurries produced from whole-round cores with H2-added artificial seawater medium using radioisotope techniques (14C-bicarbonate, 14C-methane, and 35S-sulfate, respectively). Preliminary results revealed two peaks of methanogenesis activity with rates in the order of 0.2 to 0.5 pmol g-1dw d-1. One peak was located within the methane-rich zone passing into the methane-sulfate transition zone (60 to 80°C incubations), while the second peak occurred close to the basement (below 1000 mbsf, 95°C incubation). Sulfate reduction activity was generally highest above 400 mbsf ( 1000 pmol cm-3 d-1, 40°C incubation). Below 400 mbsf, rates declined to levels between 0.1 and 10 pmol cm-3 d-1 (60-95 °C incubations) without a clear trend and continued until close to the bottom of the core. The results point to potentially thermophilic and hypothermophilic microorganisms that exist under very low energy conditions. Samples from AOM incubations are currently being processed and preliminary results will be presented at the meeting as well as the results for sulfate reduction incubations with methane and acetate amendments.

The IODP NanTroSEIZE Transect: Accomplishments and Future Plans

NASA Astrophysics Data System (ADS)

Tobin, H. J.; Kinoshita, M.; Araki, E.; Byrne, T. B.; Kimura, G.; McNeill, L. C.; Moore, G. F.; Saffer, D. M.; Underwood, M.; Saito, S.

2009-12-01

The Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) is a decade-long project to investigate the processes and properties that determine the nature of frictional locking, creep and other fault behavior governing seismogenic rupture and tsunamigenesis on a major plate boundary where great subduction earthquakes occur. The main goal of the science plan is to sample and instrument the key faults in several locations across the transition from those dominated by frictionally stable, aseismic processes vs. those hypothesized to be frictionally locked (seismogenic) faults of the megathrust system. The transect includes primary drill sites from the incoming plate, across the outer accretionary complex of the lower slope, to the Kumano forearc basin and underlying up-dip end of the likely locked plate interface. The scale of this project required a division into multiple stages of operations, spanning a number of years and IODP expeditions. From September 2007 through October 2009, the NanTroSEIZE science team has achieved many of its primary goals during 5 expeditions. Completed drill sites to date include penetrations ranging from ~200 m to ~1600 m below the sea floor that have documented the faults and wall rocks of both the frontal thrust and out-of-sequence splay faults in the accretionary system, the sedimentary section of the subducting plate, and the thick forearc basin sedimentary record and underlying older subduction complex in the hanging wall of the main plate interface. Major results include characterization of: the fault zone geology, strain localization, and physical properties shallower than ~ 1 km, the distribution of ambient (and paleo-) stress orientations across the transect, the absence of evidence for focused fluid channeling along the principal shallow fault systems, and the tectonic history of the subduction system. Extensive downhole measurements and a 2-ship VSP have further documented stress, pressure, rock strength, and elastic properties around the boreholes. The first temporary long-term monitoring instruments are now in place in one sealed borehole, recording pore pressure and temperature. The most ambitious aspect of the NanTroSEIZE project remains for the now-scheduled next stage: drilling to ~ 7000 m below the sea bed across the faults of the main plate boundary, then placing long-term monitoring instruments into both deep and shallow sealed borehole observatories - all to test hypotheses of locking, strain accumulation, and interseismic fault processes.

A shape and compositional analysis of ice-rafted debris in cores from IODP Expedition 323 in the Bering Sea

NASA Astrophysics Data System (ADS)

Dadd, Kelsie; Foley, Kristen

2016-03-01

Sediment cores recovered during IODP Expedition 323 in the Bering Sea, northern Pacific, contained numerous ice-rafted debris (IRD) clasts up to 85 mm in length. The physical properties (including roundness and sphericity) of 136 clasts from the working half of the cores, a subsample of the total clast number, were analysed and their composition determined using standard petrographic techniques. After removal of pumice and possible fall-in derived material from the clast population, a total of 86 clasts from the original collection were considered to be IRD. While roundness and sphericity vary greatly in the clast population, the IRD are predominately discoid in shape with oblate/prolate indices typically between -5 and 5. There are four time periods over the approximately 4.5 Ma sample interval, 0.36-0.67 Ma, 0.82-1.06 Ma 1.54-1.77 Ma and >3.28 Ma, where there are no IRD in the sample set for sites of the Bering slope, suggesting that these times may have been ice-free. Most clasts show some rounding and are likely to have spent time on beaches with wave action. Wave action on beaches suggests periods of no ice or only seasonal sea-ice. The low roundness values of other clasts, however, suggest they underwent little working and, therefore, the presence of glaciers or more permanent sea-ice at times in those locations. The abundance of rounded and unfaceted clasts as IRD suggests a lack of large ice sheets in the area during cool periods. Clast composition of the IRD is divided into four broad groups, basalt and andesite, granite and metamorphic, sedimentary, and felsic volcanic. The granite and metamorphic and more mature sedimentary lithologies are most likely derived from the Alaskan continental margin, while the extrusive igneous clasts could be derived from a variety of volcanic sources surrounding the Bering Sea, both emergent now or emergent at times of lower sea level. There is only a poor correlation with IRD abundance and marine isotope stages (MIS) for the time period <1 Ma. Abundant IRD occurs in MIS 3 and can be correlated with MIS back to 400 kyr but not to older ages. This suggests that the abundance of IRD >2 mm transported by sea-ice may not be a good indicator of past climate conditions.

The oceanographic and climatic evolution of the Paleogene Southern Ocean (Arne Richter Award for Outstanding Young Scientists Lecture)

NASA Astrophysics Data System (ADS)

Bijl, Peter; Houben, Alexander J. P.

2014-05-01

Continental-scale ice sheets first appeared in Antarctica following long-term cooling through the Eocene Epoch (56-34 Ma) within the Paleogene Period (65.5-23 Ma). Both the long-term cooling following early Eocene hothouse climates and the onset of large-scale glaciation itself has been related to the gradual decline of atmospheric greenhouse gas concentrations. Although much work is now centered in improving techniques for reconstructing past atmospheric pCO2, at present proxy-based reconstructions of atmospheric greenhouse gases for the Paleogene are of low temporal resolution and subject to a large degree of uncertainty. Furthermore, long-term mid-Eocene surface water cooling appears to have been confined to high- and mid-latitudes only, with little to no cooling in the tropical regions. This observation questions the role of atmospheric greenhouse gas (notably CO2) decline as a primary cause of Eocene climate cooling. Furthermore, the greenhouse-gas hypothesis has now superceded long-held hypothesis that the opening of southern ocean tectonic gateways cooled Antarctica. A direct relationship between the deepening of the Tasmanian Gateway and Antarctic glaciation has been refuted by accurate dating of this tectonic event, indicating that the Tasmanian Gateway deepened 2 million years prior to Antarctic glaciation. However, the precise secondary role of gateway evolution on Antarctic climate change is not well constrained. On the other hand, it is increasingly apparent that the Southern Ocean was the main region for intermediate-deep water formation in the Paleogene, which implies that even environmental change with regional effects may have had direct implications for global climate change. While the forcing mechanism that pushed Antarctica towards fully glaciated conditions is likely atmospheric pCO2 decline across a critical threshold, the regional environmental responses are not well constrained. Numerical modeling studies suggest that in conjunction with the buildup of continental ice on Antarctica, sea-ice may have first developed along the margin of East Antarctica Margin, but this conclusion lacks support from field evidence. Other numerical models predict that hysteresis effects within the ice sheet render a continental-size Antarctic ice sheet rather insensitive to warming. In contrast, deep-water benthic foraminiferal oxygen isotope records across the Oligocene suggest dramatic waxing and waning of Antarctic ice sheets. In summary, the complex interaction of climate forcings and responses following the opening and subsequent deepening of the Southern Ocean gateways, as well as the precise relationship between Southern Ocean oceanographic change, sea ice formation and continental ice dynamics are as yet poorly understood. In my presentation, I will provide an overview of our recent palynological and organic geochemical studies on Eocene sediments from the Southern Ocean that addresses some of these uncertainties. The presented studies were only possible through access to ocean sediments collected and curated by the several scientific ocean drilling programs (DSDP, ODP, IODP). IODP Expedition 318 drilled the Antarctic Margin in 2010, and recovered sediments from both pre-glacial and early glacial phases of Antarctic climate evolution. Using these drill cores together with sediments retrieved during previous expeditions we can now evaluate the robustness of the results of numerical models with field data. Strata sampled at IODP Site U1356 represent a thick and relatively complete (albeit compromised by core gaps) Eocene- Oligocene succession that is chronostratigraphically well-calibrated in the context of of nannoplankton- dinoflagellate cyst (dinocyst) and paleomagnetism. Notably, this record yields diverse dinocysts assemblages and organic molecular biomarkers, which we can use to investigate changes in surface-water paleoenvironmental changes through the Eocene and Oligocene to provide answers to these outstanding questions.

Past seismic slip-to-the-trench recorded in Central America megathrust

NASA Astrophysics Data System (ADS)

Vannucchi, Paola; Spagnuolo, Elena; Aretusini, Stefano; Di Toro, Giulio; Ujiie, Kohtaro; Tsutsumi, Akito; Nielsen, Stefan

2017-12-01

The 2011 Tōhoku-Oki earthquake revealed that co-seismic displacement along the plate boundary megathrust can propagate to the trench. Co-seismic slip to the trench amplifies hazards at subduction zones, so its historical occurrence should also be investigated globally. Here we combine structural and experimental analyses of core samples taken offshore from southeastern Costa Rica as part of the Integrated Ocean Drilling Program (IODP) Expedition 344, with three-dimensional seismic reflection images of the subduction zone. We document a geologic record of past co-seismic slip to the trench. The core passed through a less than 1.9-million-year-old megathrust frontal ramp that superimposes older Miocene biogenic oozes onto late Miocene-Pleistocene silty clays. This, together with our stratigraphic analyses and geophysical images, constrains the position of the basal decollement to lie within the biogenic oozes. Our friction experiments show that, when wet, silty clays and biogenic oozes are both slip-weakening at sub-seismic and seismic slip velocities. Oozes are stronger than silty clays at slip velocities of less than or equal to 0.01 m s-1, and wet oozes become as weak as silty clays only at a slip velocity of 1 m s-1. We therefore suggest that the geological structures found offshore from Costa Rica were deformed during seismic slip-to-the-trench events. During slower aseismic creep, deformation would have preferentially localized within the silty clays.

Why Drill Here? Teaching to Build Student Understanding of the Role Sediment Cores from Polar Regions play in Interpreting Climate Change

NASA Astrophysics Data System (ADS)

Pound, K. S.; St. John, K.; Krissek, L. A.; Jones, M. H.; Leckie, R. M.; Pyle, E. J.

2008-12-01

That the ocean basins provide a record of past global climate changes through their sediment cores is often a surprise or novel idea for students. Equally surprising to many students is the fact that current research is being undertaken in remote polar regions, even though sedimentary records already exist from the low and mid latitude regions. Students are often also perplexed about how decisions are made regarding the selection of drill sites in the polar regions. Using an inquiry-based approach we are developing a series of simple exercises that are scaffolded to build student understanding around the question "Why Drill Here?" The exercises are based on IODP Expedition 302 (ACEX) in the Arctic, and on the Antarctic Geological Drilling (ANDRILL) program, which are used as case studies. The "Why Drill Here?" question is addressed at multiple levels so students can formulate a scientific rationale behind selection of sites for seafloor drilling in the Arctic and Antarctic regions. Technological challenges and solutions to doing field-based science in polar regions are explored. Finally, a subset of research results are investigated and compared with the current scientific paradigm on Cenozoic climate evolution to demonstrate that science is an evolving process. These exercises can be adapted for use in a variety of Introductory Earth Science classes.

Temporal changes in Quaternary paleoenvironment and ostracode fauna in the eastern Indian Sea off Western Australia (IODP, Exp. 356, site U1461)

NASA Astrophysics Data System (ADS)

Iwatani, H.; Yasuhara, M.; Angue Minto'O, C. M.; Bassetti, M. A.; Expedition 356 Scientists, I.

2016-12-01

The International Ocean Discovery Program Expedition 356 drilled on seven sites off Western Australia to reveal the history of the Indonesian throughflow, the effects of the Australian monsoon, and the subsidence of the northwest shelf of Australia. To achieve these objectives, we investigated paleoenvironmental evolutions in this region during the Quaternary period using high-resolution statistical analyses of the fossil Ostracoda (Crustacea) as an effective environmental indicator. For the investigation, we used a sediment core obtained from an area off Western Australia in the eastern Indian Sea (site: U1461; water depth: 128 m; latitude: 20°, 12.85' S; longitude: 115°, 03.94' E). The upper part of the core mainly comprises alternating beds of darker-colored packstone/wackestone and light-colored wackestone/mudstone. The light-colored wackestone/mudstone beds often contain fecal pellets and well-preserved molluscan fossils. We investigated fossil ostracode faunal composition and species diversity changes during the deposition of the study site. Many well-preserved ostracodes were recorded in the studied cores. Many of collected species are extant taxa that inhabit the upper sublittoral regions as reported from around the recent Indian Ocean off northwestern Australia. Ostracode assemblages, abundance, and diversity drastically changed during the deposition, and they are concordant with sedimentary facies. Here we will discuss the relationships between these paleo-communities changes and paleoenvironmental conditions.

The last deglacial retreat history of the East Antarctic Ice Sheet recorded in sediments from off the Wilkes Land Coast

NASA Astrophysics Data System (ADS)

Yokoyama, Y.; Yamane, M.; Miyairi, Y.; Suga, H.; Dunbar, R. B.; Ohkouchi, N.

2017-12-01

Timing of past ice sheet retreat of Antarctic continent has been debated with regards to the global sea level changes since the Last Glacial Maximum (LGM) centered at around 20 ka. Exposure dating using cosmogenic radio nuclide (CRN) for glacial deposits have been widely used to reconstruct the last deglacial history though this cannot apply where no-ice free coasts are existed. One such location is the Wilkes Land where the East Antarctic Ice Sheet (EAIS) is situated directory on seafloor. Sediment cores obtained off the Wilkes Land coast successfully retrieved cores during the Intergrated Ocean Drilling Program (IODP) Expedition 318 (Escuita et al., 2011). Major obstacle to obtain reliable chronology for marine cores around Antarctica is sparsity of carbonate materials such as foraminifera. Thus compound-specific radiocarbon analysis (CSRA) has been used and we applied CSRA to the sediments obtained off the Wilkes land coast. The CSRA targeted C16 and C16:1 fatty acid due to their high degradation rate. Hence low concentrations of these compounds are expected. We found major sedimentation occurred since the beginning of Holocene. The result is then compared to the previously reported dates from the land based CRN dates (eg., Mckintosh et al., 2013; Yamane et al., 2011) to discuss the timing of retreat of EAIS.

45 CFR 303.101 - Expedited processes.

Code of Federal Regulations, 2010 CFR

2010-10-01

... Public Welfare Regulations Relating to Public Welfare OFFICE OF CHILD SUPPORT ENFORCEMENT (CHILD SUPPORT ENFORCEMENT PROGRAM), ADMINISTRATION FOR CHILDREN AND FAMILIES, DEPARTMENT OF HEALTH AND HUMAN SERVICES STANDARDS FOR PROGRAM OPERATIONS § 303.101 Expedited processes. (a) Definition. Expedited processes means...

Reconstructing Holocene palaeo-environmental conditions in the Baltic: A multi-proxy comparison from the Little Belt (IODP Expedition 347, Site M0059)

NASA Astrophysics Data System (ADS)

Kotthoff, Ulrich; Andrén, Elinor; Andrén, Thomas; Ash, Jeanine; Bauersachs, Thorsten; Fanget, Anne-Sophie; Granoszewski, Wojciech; Groeneveld, Jeroen; Krupinski, Nadine; Peyron, Odile; Slomp, Caroline; Stepanova, Anna; Warnock, Jonathan; van Helmond, Niels; Expedition 347 Science Party

2016-04-01

Some of the largest marine environmental impacts from ongoing global climate change are occurring in continental shelf seas and enclosed basins, including severe oxygen depletion, intensifying stratification, and increasing temperatures. In order to predict future changes in water mass conditions, it is essential to reconstruct how these conditions have changed in the past against the background of climate changes. The brackish Baltic Sea is one of the largest semi-enclosed basins worldwide, and its sediment records provide a unique opportunity to analyse palaeo-environmental and climate change in central and northern Europe. IODP Expedition 347 recovered an exceptional set of sediment cores from the Baltic Sea which allow high-resolution reconstructions in unprecedented quality. We present a comparison of commonly-used proxies to reconstruct palaeoecosystems, -temperatures, and -salinity from IODP Site M0059 in the Little Belt over the past ˜8000 years. Our aim is to reconstruct the development of the terrestrial and marine ecosystems in the research area and the related environmental conditions, and to identify potential limitations of individual proxies. The age model for Site M0059 is based on 14Cdating, biostratigraphic correlation with neighbouring terrestrial pollen records, and sediment stratigraphy. Sedimentary organic carbon content and the bulk elemental composition have been measured, and can be used to determine the depositional environment and degree of oxygen depletion (e.g., Mo, Corg/Ptot). Pollen is used as proxy for vegetation development in the hinterland of the southern Baltic Sea and as a land/air-temperature proxy. Comparison with dinoflagellate cysts, insect remains, and green algae remains from the same samples provides a direct land-sea comparison. The application of the modern analogues technique to pollen assemblages has previously yielded precise results for late Pleistocene and Holocene datasets, including specific information on seasonality, but pollen-based reconstructions for Northern Europe may be hampered by plant migration effects. Palynomorph analyses are therefore complemented with analyses of lipid palaeothermometers, such as TEX86 and the long chain diol index (LDI), to reconstruct variations in Baltic Sea surface temperatures (SST). In addition, the MBT/CBT proxy is used to infer past changes in mean annual air temperatures (MAAT). Benthic foraminiferal δ18O and δ13C measurements (monospecific) and foraminifera and ostracod faunal assemblage analyses allow us to estimate bottom water salinity and environmental changes qualitatively and quantitatively. Low bottom water salinity (˜23 in bottom waters) and varying diagenesis in the Little Belt's organic-rich sediments complicates the application of benthic foraminiferal Mg/Ca as a palaeotemperature proxy. Reliable bottom water temperatures, however, are reconstructed using clumped isotope analyses of mollusc material. In addition, diatoms and the diol index (DI) are analysed to determine variation in salinity of the Baltic Sea's surface waters over the investigated time period. The results of this inter-proxy comparison study will be used to reconstruct gradients between different settings, e.g. how water column stratification developed, possibly if and how changes in seasonality occurred, and to identify the circumstances under which specific proxies may be affected by secondary impacts.

38 CFR 20.1500 - Rule 1500. Expedited Claims Adjudication Initiative.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Claims Adjudication Initiative. 20.1500 Section 20.1500 Pensions, Bonuses, and Veterans' Relief... Adjudication Initiative-Pilot Program § 20.1500 Rule 1500. Expedited Claims Adjudication Initiative. (a) Purpose. The Expedited Claims Adjudication Initiative is a pilot program designed to streamline the claims...

The CoreWall Project: An Update for 2007

NASA Astrophysics Data System (ADS)

Yu-Chung Chen, J.; Higgins, S.; Hur, H.; Ito, E.; Jenkins, C. J.; Johnson, A.; Leigh, J.; Morin, P.; Lee, J.

2007-12-01

The CoreWall Suite is a NSF-supported collaborative development for a real-time core description (Corelyzer), stratigraphic correlation (Correlater), and data visualization (CoreNavigator) software to be used by the marine, terrestrial and Antarctic science communities. The overall goal of the Corewall software development is to bring portable cross-platform tools to the broader drilling and coring communities to expand and enhance data visualization and enhance collaborative integration of multiple datasets. The CoreWall Project is now in its second year and significant progress has been made on all 3 software components. Corelyzer has undergone 2 field deployments and testing by ANDRILL program in 2006 (and again in Fall 2007) and by ICDP's SAFOD project (summer 2007). In addition, Corewall group and ICDP are working together so that the core description (DIS) system can expose DIS core data directly into Corelyzer seamlessly and be available to future ICDP and IODP-Mission Specific Platform expeditions. Educators have also taken note of the software's ease of use and strong visualization capabilities to begin exploring curriculum projects with Corelyzer software. To ensure that the software development is integrated with other community IT activities the development of the U.S. IODP-Phase 2 Scientific Ocean Drilling Vessel (SODV), a Steering Committee was constituted. It is composed of key U.S. IODP and related database (e.g., CHRONOS, SedDB) developers and users as well as representatives of other core-based enterprises (e.g., ANDRILL, ICDP, LacCore). Corelyzer (CoreWall's main visual core description tool) software displays digital core images from one or more cores along with discrete data streams (eg. physical properties, downhole logs) and nested images (eg. thin sections, fossils) to provide a robust approach to the description of sediment cores. Corelyzer's digital image handling allows the cores to be viewed from micron to km scale determined by the image resolution along a sliding plane, effectively making it a "digital microscope". Detailed features such as lithologic variation, macroscopic grain size variation, bioturbation intensity, chemical composition and micropaleontology are easier to interpret and annotate. Significant new capabilities have been added to allow for importing multiple images and data types, sharing/exporting Corelyzer "work sessions" for multiple users, enhanced annotations, as well as support for other activities like examining clasts, and sample requests. The new Correlator software, the updated version of Splicer/Sagan software used by ODP for over 10 years, has been ported into a single new analysis tool that will work across multiple platforms and interact seamlessly with both JANUS (ODP's relational database), CHRONOS, PetDB, SedDB, dbSEABED and other databases. This functionality will result in a CoreWall Suite module that can be used and distributed anywhere for stratigraphic and age correlation tasks. CoreNavigator, a spatial data discovery tool, has taken on a virtual Globe interface that allows users to enter Corelyzer from a geographic-visual standpoint.

A recent investigation of gas hydrate as a factor in northern Cascadia accretionary margin frontal ridge slope failures and cold seep biogeochemistry

NASA Astrophysics Data System (ADS)

Haacke, R.; Riedel, M.; Pohlman, J.; Rose, K.; Lapham, L.; Hamilton, T. S.; Enkin, R.; Spence, G.; Hyndman, R.

2008-12-01

In August 2008, a research expedition was conducted on the n. Cascadia margin by the Geological Survey of Canada (GSC) as part of the Earth Science Sector, Natural Gas Hydrate Program, Natural Resources Canada (NRCan). This collaboration included researchers from several universities as well as Canadian and U.S. government agencies. The primary objective was to determine the impact of gas hydrate on slope stability along the frontal ridges of the N. Cascadia accretionary wedge. Multibeam bathymetry data indicate numerous slope collapse features along the frontal ridges. To constrain the cause and timing of the collapse features, sedimentological, physical property and geochemical studies were conducted at several slump areas. Four cores were collected from within the headwall, apron and sole of the slumped material of 'Lopez Slide', a failure area detected prior to IODP Expedition 311. Directly south of Lopez Slide at a slump feature named 'Slipstream Slide', a 5-core transect extended from the headwall scarp to the toe of the slide deposits. Slipstream Slide is a series of en echelon box-like slump blocks bounded by transverse faults that cross-cut that frontal ridge. One additional core from a slump-feature further south (Chunk Slide) was also recovered. Onboard analyses suggest that the slump occurrences are not related to the last mega-thrust earthquake that occurred at the N. Cascadia subduction zone in January 1700. However, the slumps could have been triggered by earlier such earthquakes. Further analyses and age determinations are underway to confirm the linkages between slumps and the mega-thrust earthquake cycle and other possible trigger mechanisms such as eustatic sea level changes. The secondary objective of the expedition was a multidisciplinary program that included microbiological, geochemical, geophysical and sedimentological studies designed to advance our understanding of the environmental factors that control methane fluxes and oxidation at cold seeps of active methane venting (seen as bubble-plumes in echo-sounder data). A series of cores were taken from Bullseye Vent, Barkley Canyon and a newly discovered vent 10 km west of Bullseye Vent. These investigations are closely linked to the NEPTUNE project that will deploy long-term monitoring stations on the N. Cascadia margin in 2009 for methane hydrate studies. Shipboard scientific party in alphabetical order: R. Enkin (NRCan), L. Esteban (NRCan), R. Haacke (NRCan), T.S. Hamilton (Camosun), M. Hogg (Camosun), L. Lapham (Florida State), G. Middleton (NRCan), P. Neelands (NRCan), J. Pohlman (USGS), M. Riedel (McGill), K. Rose (USDOE), A. Schlesinger (UVic), G. Standen (Geoforce), A. Stephenson (UVic), S. Taylor (NRCan), W. Waite (USGS), X. Wang (McGill)

Future scientific drilling in the Arctic Ocean: Key objectives, areas, and strategies

NASA Astrophysics Data System (ADS)

Stein, R.; Coakley, B.; Mikkelsen, N.; O'Regan, M.; Ruppel, C.

2012-04-01

In spite of the critical role of the Arctic Ocean in climate evolution, our understanding of the short- and long-term paleoceanographic and paleoclimatic history through late Mesozoic-Cenozoic times, as well as its plate-tectonic evolution, remains behind that from the other world's oceans. This lack of knowledge is mainly caused by the major technological/logistic problems in reaching this permanently ice-covered region with normal research vessels and in retrieving long and undisturbed sediment cores. With the Arctic Coring Expedition - ACEX (or IODP Expedition 302), the first Mission Specific Platform (MSP) expedition within IODP, a new era in Arctic research began (Backman, Moran, Mayer, McInroy et al., 2006). ACEX proved that, with an intensive ice-management strategy, successful scientific drilling in the permanently ice-covered central Arctic Ocean is possible. ACEX is certainly a milestone in Arctic Ocean research, but - of course - further drilling activities are needed in this poorly studied ocean. Furthermore, despite the success of ACEX fundamental questions related to the long- and short-term climate history of the Arctic Ocean during Mesozoic-Cenozoic times remain unanswered. This is partly due to poor core recovery during ACEX and, especially, because of a major mid-Cenozoic hiatus in this single record. Since ACEX, a series of workshops were held to develop a scientific drilling strategy for investigating the tectonic and paleoceanographic history of the Arctic Ocean and its role in influencing the global climate system: - "Arctic Ocean History: From Speculation to Reality" (Bremerhaven/Germany, November 2008); - "Overcoming barriers to Arctic Ocean scientific drilling: the site survey challenge" (Copenhagen/Denmark, November 2011); - Circum-Arctic shelf/upper continental slope scientific drilling workshop on "Catching Climate Change in Progress" (San Francisco/USA, December 2011); - "Coordinated Scientific Drilling in the Beaufort Sea: Addressing Past, Present and Future Changes in Arctic Terrestrial and Marine Systems" (Kananaskis, Alberta/Canada, February 2012). During these workshops, key areas and key scientific themes as well as drilling and site-survey strategies were discussed. Major scientific themes for future Arctic drilling will include: - The Arctic Ocean during the transition from greenhouse to icehouse conditions and millennial scale climate changes; - Physical and chemical changes of the evolving Polar Ocean and Arctic gateways; - Impact of Pleistocene/Holocene warming and sea-level rise on upper continental slope and shelf gas hydrates and on shelf permafrost; - Land-ocean interactions; - Tectonic evolution and birth of the Arctic Ocean basin: Arctic ridges, sea floor spreading and global lithosphere processes. When thinking about future Arctic drilling, it should be clearly emphasized that for the precise planning of future Arctic Ocean drilling campaigns, including site selection, evaluation of proposed drill sites for safety and environmental protection, etc., comprehensive site survey data are needed first. This means that the development of a detailed site survey strategy is a major challenge for the coming years. Here, an overview of perspectives and plans for future Arctic Ocean drilling will be presented.

Refining the Bengal Fan stratigraphy - A first correlation of IODP Expedition 354 results and seismic data from the Bay of Bengal

NASA Astrophysics Data System (ADS)

Schwenk, Tilmann; Spiess, Volkhard; Bergmann, Fenna; France-Lanord, Christian; Klaus, Adam

2016-04-01

The Bengal Fan covers the floor of the entire Bay of Bengal from the continental margins of India and Bangladesh to the sediment-filled Sunda Trench off Myanmar and the Andaman Islands, and along the west side of the Ninetyeast Ridge. The deposition and progradation of the Bengal Fan started in the Eocene after the collision of India with Asia resulting in the build-up of the Himalaya and the formation of a large proto-Bay of Bengal. Continued convergence of the Indian and Australian plates with the Southeast Asian plate reduced the size of the bay and focused the source of turbidites finally into the present Bengal Basin, Bangladesh shelf, and the shelf canyon "Swatch of no Ground". Today, the Bengal Fan is mainly fed by the sediment load of the Ganges and Brahmaputra rivers, which drain the Himalayas at its southern and northern slope, respectively, and deliver their load to the delta in the Bengal Basin, to the Bengal Shelf and to the deep sea fan. Thus the Bengal Fan is a suitable recorder to study interactions among the growth of the Himalaya and Tibet, the development of the Asian monsoon, and processes affecting the carbon cycle and global climate. Because sedimentation in the Bengal Fan responds to both, climate and tectonic processes, its terrigenous sediment records the past evolution of both the Himalaya and regional climate. This evolution is also expressed in the stratigraphy of the fan in terms of unconformities and key horizons, average sedimentation rates as a function of distance from the basement ridges at 85°E and 90°E and the presence or absence of channel-levee systems. The histories of the Himalaya/Tibetan system and the Asian monsoon require sampling different periods of time with different levels of precision. Therefore IODP Expedition 354 drilled in February-March 2015 a seven site, 320 km-long transect across the Bengal Fan at 8°N. This strategy has been chosen because sediment transport took place by turbidity currents following transport channels leading to deposition on and between levees. As a consequence, depocenters were laterally shifting over hundreds of kilometers on millennial time scales. To archive a spatial and temporal overview of this primarily turbiditic depositional system, three deep penetration and additional four shallow holes were drilled. By that Expedition 354 has extended back the record of early fan deposition by 10 Ma into the Late Oligocene. As result of this drilling, numerous stratigraphic marker horizons across the transect could be identified, cored and dated. In combination with the available seismic data collected during the RV Sonne cruises SO125 and SO188, a detailed reconstruction of channel-levee growing, migration, abandonment, reoccupation and overall uniform growth of the fan can be carried out.

Palaeointensity determinations and rock magnetic properties on rocks from Izu-Bonin-Mariana fore-arc (IODP Exp. 352).

NASA Astrophysics Data System (ADS)

Carvallo, Claire; Camps, Pierre; Sager, Will; Poidras, Thierry

2017-04-01

IODP Expedition 352 cored igneous rocks from the Izu-Bonin-Mariana fore-arc crust: Sites U1440 and U1441 recovered Eocene basalts and related rocks whereas Sites U1439 and U1442 recovered Eocene boninites and related rocks. We selected samples from Holes U1439C, U1440B and U1440A for paleointensity measurements. Hysteresis measurements and high and low-temperature magnetization curves show that samples from Hole U1440B undergo magnetochemical changes when heated and are mostly composed of single-domain (SD) or pseudo-single-domain (PSD) titanomaghemite. In contrast, the same measurements show that most selected samples from Holes U1439C and U1442A are thermally stable and are composed of either SD or PSD titanomagnetite with very little titanium content, or SD ferromagnetic grains with a large paramagnetic contribution. Thellier-Thellier paleointensity experiments carried out on U1439C and U1442A samples give a good success rate of 25/60 and Virtual Dipole Moment values between 1.3 and 3.5 ×1022 Am2. Multispecimen paleointensity experiments carried out on 55 samples from Hole U1440B (divided into 4 groups) and 20 from Hole U1439C gave poor quality result, but they seem to indicate a VDM around 4-6 ×1022 Am2 in Hole U1440B fore-arc basalts. These results are in agreement with the low few VDM values previously measured on rocks from Eocene. However, they do not support an inverse relationship between intensity of the field and rate of reversal, since the rate of reversal in Eocene was rather low.

Palaeointensity determinations and magnetic properties on Eocene rocks from Izu-Bonin-Mariana forearc (IODP Exp. 352)

NASA Astrophysics Data System (ADS)

Carvallo, C.; Camps, P.; Sager, W. W.; Poidras, T.

2017-09-01

IODP Expedition 352 cored igneous rocks from the Izu-Bonin-Mariana forearc crust. Cores from Sites U1440 and U1441 recovered Eocene basalts and related rocks and cores from Sites U1439 and U1442 recovered Eocene boninites and related rocks. We selected samples from Holes U1439C, U1440B and U1442A for palaeointensity measurements. Hysteresis measurements and high and low-temperature magnetization curves show that samples from Hole U1440B undergo magneto-chemical changes when heated and are mostly composed of single-domain (SD) or pseudo-single-domain (PSD) titanomaghemite. In contrast, the same measurements show that most selected samples from Holes U1439C and U1442A are thermally stable and are composed of either SD or PSD titanomagnetite with very little titanium content, or SD ferromagnetic grains with a large paramagnetic contribution. Thellier-Thellier palaeointensity experiments carried out on U1439C and U1442A samples give a good success rate of 25/60 and Virtual Dipole Moment (VDM) values between 1.3 and 3.5 × 1022 Am2. Multispecimen palaeointensity experiments with the domain-state corrected method carried out on 55 samples from Hole U1440B (divided into four groups) and 20 from Hole U1439C gave poor quality results, but indicated a VDM around 4-6 × 1022 Am2 in Hole U1440B forearc basalts. These results are in agreement with the few, low VDM values previously measured on Eocene rocks. However, they do not support an inverse relationship between field intensity and reversal rate for this period of time, since the Eocene reversal rate was low.

Microstructural observations on hydrothermal veins of Site U1414, IODP Expedition 344 (CRISP 2)

NASA Astrophysics Data System (ADS)

Brandstätter, Jennifer; Kurz, Walter; Rogowitz, Anna

2017-04-01

The erosive active margin offshore Osa Peninsula (Costa Rica) is characterized by the subducting Cocos Plate with its topographic height, the aseismic Cocos Ridge, which has lifted the seismogenic zone in the reach of scientific drilling. To understand the processes occurring in the subducting Cocos Plate in the vicinity to the Middle America Trench, we investigated microstructures in hydrothermal veins, transecting the lithified sediments and the igneous basement of IODP Hole U-1414A. Mechanical e-twinning occurred mainly in the blocky calcite veins in the lithified sediments, rather than in the fibrous calcite veins within the Cocos Ridge basalt. The differential stress, obtained from two different piezometers, indicate mean differential stresses of approximately 53 and 82 MPa. The majority of the twins show a significant thickness (up to 120 µm), straight twin boundaries and are indicative for deformation temperatures between 150 to 300°C. The presence of additional deformation structures, such as undulose extinction and subgrain boundaries, indicates intracrystalline-plastic deformation by dislocation creep. The comparison of the EBSD data from two samples within the lithified sedimentary unit indicates diverse deformation temperatures. Variation in subgrain size observed for the different samples can be related to local variations in differential stress. The results of different microstructural observations showed, that the deformational history of Site 344-U1414 is characterized by distinct tectonic phases, occurring during the movement of the Cocos Ridge from its location of origin (the Galapagos hotspot) to the convergent margin offshore Costa Rica. The causes for these changes in deformation mechanisms in the studied rocks are ascribed to magmatic advection resulting in an increase of temperature and decrease of critical resolved shear stresses, as well as the bending of the Cocos plate adjacent to the Middle American trench.

Melt-rock interactions and fabric development of peridotites from North Pond in the Kane area, Mid-Atlantic Ridge: Implications of microstructural and petrological analyses of peridotite samples from IODP Hole U1382A

NASA Astrophysics Data System (ADS)

Harigane, Yumiko; Abe, Natsue; Michibayashi, Katsuyoshi; Kimura, Jun-Ichi; Chang, Qing

2016-06-01

North Pond is an isolated sedimentary pond on the western flank of the Kane area along the Mid-Atlantic Ridge. Drill-hole U1382A of IODP Expedition 336 recovered peridotite and gabbro samples from a sedimentary breccia layer in the pond, from which we collected six fresh peridotite samples. The peridotite samples came from the southern slope of the North Pond where an oceanic core complex is currently exposed. The samples were classified as spinel harzburgite, plagioclase-bearing harzburgite, and a vein-bearing peridotite that contains tiny gabbroic veins. No obvious macroscopic shear deformation related to the formation of a detachment fault was observed. The spinel harzburgite with a protogranular texture was classified as refractory peridotite. The degree of partial melting of the spinel harzburgite is estimated to be ˜17%, and melt depletion would have occurred at high temperatures in the uppermost mantle beneath the spreading axis. The progressive melt-rock interactions between the depleted spinel harzburgite and the percolating melts of Normal-Mid Ocean Ridge Basalt (N-MORB) produced the plagioclase-bearing harzburgite and the vein-bearing peridotite at relatively low temperatures. This implies that the subsequent refertilization occurred in an extinct spreading segment of the North Pond after spreading at the axis. Olivine fabrics in the spinel and plagioclase-bearing harzburgites are of types AG, A, and D, suggesting the remnants of a mantle flow regime beneath the spreading axis. The initial olivine fabrics appear to have been preserved despite the later melt-rock interactions. The peridotite samples noted above preserve evidence of mantle flow and melt-rock interactions beneath a spreading ridge that formed at ˜8 Ma.

Movement of fluids in the Nankai Trough area: Insights from 129I and halogen distributions along the IODP NanTroSEIZE transect

NASA Astrophysics Data System (ADS)

Tomaru, Hitoshi; Fehn, Udo

2015-01-01

Halogen concentrations and 129I/I ratios were determined in pore waters from the Nankai Trough subduction system, collected during IODP Expeditions 315, 316, 322, and 333 along the NanTroSEIZE transect. The transect allowed the first direct comparison of iodine results across an active subduction system, from subducting oceanic sediments to the accretionary prism, and the overlying forearc basin. In contrast to the other halogens (Cl and Br) iodine concentrations show large variations within and among the cores at all sites landward of the trough, I concentrations increase rapidly with depth and reach values several orders of magnitude higher than those in seawater, but are only slightly higher than seawater values at the seaward sites. Methane concentrations follow a similar pattern. Host sediments of the fluids are younger than 7 Ma in all the cores, but the ages of iodine in pore waters at the landward sites reach values beyond 30 Ma. In contrast, iodine seaward of the trough is in isotopic equilibrium with the host sediments, resulting in very similar iodine and sediment ages. The distribution of iodine concentrations and ages indicates that iodine at the landward sites has been transported there in aqueous fluids, probably together with methane, from old formations in the upper plate. The specific fluid pathways potentially were influenced by features such as the megasplay fault in the prism or the décollement. The results demonstrate large-scale transport of fluids carrying iodine and other compounds such as methane from old layers in the upper plate to surface locations landward of the Nankai Trough, while separate, but only local hydrologic processes occur in the marine sediments moving toward the trough.

IODP Site 1476: 7.5 Million Year Record of Southeast African Climate

NASA Astrophysics Data System (ADS)

Cantu, K.; Norris, R. D.

2017-12-01

The primary focus of IODP Expedition 361 was Southeast African Climate. Site 1476 in the northern Mozambique Channel yielded a sediment record going back roughly 7.6 million years, a time frame particularly interesting due to its relevance to hominid evolution. Previous paleoclimate studies from the region have included lake sediments and soil carbonate isotopes, which have been interpreted as showing a long-term trend toward increasing aridity. Lake Malawi records from the last 1.3 million years show a change during the Mid-Pleistocene Transition (MPT) from high frequency variability and generally lower lake levels to higher amplitude variability and higher lake levels punctuated by long, severe droughts resulting in extreme and long-lasting low-stands. Site 1476 cores were scanned using X-Ray Fluorescence (XRF), which gives semi-quantitative elemental abundances. Elemental abundance ratios are used as proxies for a variety of climate-related signals, such as changes in weathering rates, the nature of terrigenous material, and grain size. Looking at the site's Fe/Ca, K/Ca, and Rb/Zr ratios, the period of 4.5 to about 1.5 million years ago shows higher terrigenous flux, higher clay flux, and a smaller grain size respectively than most of the previous 3 million years, followed by a steep decline before the MPT, before transitioning to a pattern of high amplitude oscillations post-MPT. These higher amplitude oscillations seem to correspond to Lake Malawi low stands in the post-MPT period, suggesting that the higher flux of terrigenous material to site 1476 is due to higher aridity resulting in lower vegetative cover. This data also point to high climate variability in the last million years, likely contributing to the evolution and ecological adaptability of our species.

Sedimentary Controls on Foraminifera Deposition in the Bay of Bengal: Implications from Single Shell Mg/Ca and δ18O

NASA Astrophysics Data System (ADS)

Fritz-Endres, T.; Dekens, P.; Spero, H. J.; Fehrenbacher, J. S.; Spiess, V.; France-Lanord, C.

2016-12-01

Sediment cores from the Bay of Bengal present an opportunity to improve our understanding of the links between terrestrial and oceanographic climate variability. Foraminifera archive key proxies for reconstructing oceanographic conditions, but in Bengal fan sediments, fossils may have been transported via turbidity currents. Given the difference in SST and SSS variability in the southern (29.0±0.8°C; 33.9 ±0.3‰) and the northern Bay of Bengal (28.0±1.4°C; 31.6±0.8‰), it is important to determine the source of foraminifera to the sediment cores before attempting paleoceanographic reconstructions. We present paired Mg/Ca and δ18O data from single Globigerinoides sacculifer in mudline samples from three locations with differing oceanographic conditions. Two sites are from IODP Expedition 354 and one site is from the continental shelf. IODP Site U1454 (8.4°N, 85.5°E, 3721 m water depth) is near the modern active channel and more likely to be influenced by transport, while IODP site U1449 (8.4°N, 88.7°E, 3653 m water depth) is 200 km from channel activity and site 342KL (20.6°N, 90°E, 1256 m water depth) is on the continental shelf. The distribution of 70 to 80 Mg/Ca and δ18O data-points reflects the seasonal signal at the location foraminifera calcified. Mg/Ca and δ18O data from site U1449 (far from channel activity) have a distribution that most closely reflects the seasonal oceanographic conditions of the overlying water column. However, the distribution of G. sacculifer Mg/Ca and δ18O from site U1454 (near the active channel) has similarities to the distribution of the G. sacculifer Mg/Ca and δ18O data from the continental shelf. Our data suggest that foraminifera near the active channel are a mixture of shells from the overlying water column and shells transported from the northern Bay of Bengal. We suggest foraminifera can be used to reconstruct SST and δ18O in this complex depositional environment, but caution must be taken when the down-core lithology indicates regional turbidite activity and other evidence of sediment redeposition.

Initial report of the physical property measurement, ChikyuOman core description Phase I: sheeted dike and gabbro boundary from ICDP Holes GT1A, GT2A and GT3A

NASA Astrophysics Data System (ADS)

Abe, N.; Okazaki, K.; Hatakeyama, K.; Ildefonse, B.; Leong, J. A. M.; Tateishi, Y.; Teagle, D. A. H.; Takazawa, E.; Kelemen, P. B.; Michibayashi, K.; Coggon, J. A.; Harris, M.; de Obeso, J. C.

2017-12-01

We report results on the physical property measurements of the core samples from ICDP Holes GT1A, GT2A and GT3A drilled at Samail Ophiolite, Sultanate of Oman. Cores from Holes GT1A and GT2A in the lower crust section are mainly composed of gabbros (gabbro and olivine gabbro), and small amounts of ultramafic rocks (wehrlite and dunite), while cores from Hole GT3A at the boundary between sheeted dikes and gabbro are mainly composed of basalt and diabase, followed by gabbros (gabbro, olivine gabbro and oxide gabbro), and less common felsic dikes, trondhjemite and tonalite, intrude the mafic rocks. Measurements of physical properties were undertaken to characterize recovered core material. Onboard the Drilling Vessel Chikyu, whole-round measurements included X-ray CT image, natural gamma radiation, and magnetic susceptibility for Leg 1, and additional P-wave velocity, gamma ray attenuation density, and electrical resistivity during Leg 2. Split-core point magnetic susceptibility and color spectroscopy were measured for all core sections. P-wave velocity, bulk/grain density and porosity of more than 500 discrete cube samples, and thermal conductivity on more than 240 pieces from the working half of the split core sections were also measured. Physical Properties of gabbroic rocks from Holes GT1A and GT2A are similar to typical oceanic gabbros from ODP and IODP expeditions at Atlantis Bank, Southwestern Indian Ridge (ODP Legs 118, 176 and 179; IODP Exp 360) and at Hess Deep, Eastern Pacific (ODP Leg 147 and IODP Exp. 345). Average P-wave velocity, bulk density, grain density, porosity and thermal conductivity are 6.7 km/s, 2.92 g/cm^3, 2.93 g/cm^3, 0.98% and 2.46 W/m/K, respectively. P-wave velocity of samples from all three holes is inversely correlated with porosity. No clear correlation between the original lithology and physical properties is observed. GT3A cores show a wider range (e.g., Vp from 2.2 to 7.1 km/s) of values for the measured physical properties, compared to gabbros from Holes GT1A and GT2A.

Ocean Drilling Program: Publication Services: Online Manuscript Submission

Science.gov Websites

products Drilling services and tools Online Janus database Search the ODP/TAMU web site ODP/TAMU Science Operator Home ODP's main web site Publications Policy Author Instructions Scientific Results Manuscript use the submission and review forms available on the IODP-USIO publications web site. ODP | Search

Ocean Drilling Program: Web Site Access Statistics

Science.gov Websites

and products Drilling services and tools Online Janus database Search the ODP/TAMU web site ODP's main See statistics for JOIDES members. See statistics for Janus database. 1997 October November December accessible only on www-odp.tamu.edu. ** End of ODP, start of IODP. Privacy Policy ODP | Search | Database

New roles of LWD and wireline logging in scientific ocean drilling

NASA Astrophysics Data System (ADS)

Sanada, Y.; Kido, Y. N.; Moe, K.; Aoike, K.

2014-12-01

D/V Chikyu implemented by CDEX/JAMSTEC joined IODP from 2007. Various LWD (Logging While Drilling) and wireline logging have been carried out in many expeditions and for various purposes. Significant features of logging in Chikyu expeditions are many use of LWD than wireline logging, and riser dirlling. riser selected specific tools for each scientific target, and 3) carried out various borehole experiments. LWD has been more popular than wireline logging in Chikyu expeditions, because its advantages match theirs science targets. The advantages are followings. 1) LWD has more opportunities for measurement in unstable borehole, such as in the series of Nankai trough drilling expeditions. 2) LWD realtime data allows us to make realtime interpretation and operational decision. Realtime interpretation was required to set obsevartory at the properposition. 3) LWD before coring allows us to make a strategy of spot coring.We can design coring intervals for our interest and core length to improve core recovery.Riser drilling brings us merits for logging. One is hole stability (good hole condition) and the other is the use of large diameter tools. Controled drilling mud in riser drilling system prevent mud invasion to formation and mitigates collapse of borehole wall. They reduce the risk of tool stack and improve data quality. Large diameter of riser pipe enhances variation of tool seizes. A couple of new tools were used for new measurement and improvement of the data quality. For example, SonicScanner (trademark of Schulumberger) successfully measured compressional and share velocity in very low velocities at the soft sediment, where it has been difficult to measure them with conventional DSI tool (Exp319). The stress and pore pressure in the borehole were measured with the wireline logging tool, (Schlumberger MDT). The single probe tool enable to measure temporal formation fluid pressure. The double packer tool enable to fracture test by sealing and pumping in the borehole. These in-situ measurement and stress experiment data are very important to understand physical properties and mechanism of fault zone (Exp319).Those new technologies and tools also expand the envelope of scientific ocean drilling.

Exploring Microbial Life in Oxic Sediments Underlying Oligotrophic Ocean Gyres

NASA Astrophysics Data System (ADS)

Ziebis, W.; Orcutt, B.; Wankel, S. D.; D'Hondt, S.; Szubin, R.; Kim, J. N.; Zengler, K.

2015-12-01

Oxygen, carbon and nutrient availability are defining parameters for microbial life. In contrast to organic-rich sediments of the continental margins, where high respiration rates lead to a depletion of O2 within a thin layer at the sediment surface, it was discovered that O2 penetrates several tens of meters into organic-poor sediments underlying oligotrophic ocean gyres. In addition, nitrate, another important oxidant, which usually disappears rapidly with depth in anoxic sediments, tends to accumulate above seawater concentrations in the oxic subsurface, reflecting the importance of nitrogen cycling processes, including both nitrification and denitrification. Two IODP drilling expeditions were vital for exploring the nature of the deep subsurface beneath oligotrophic ocean gyres, expedition 329 to the South Pacific Gyre (SPG) and expedition 336 to North Pond, located on the western flank of the Mid-Atlantic ridge beneath the North Atlantic Gyre. Within the ultra-oligotrophic SPG O2 penetrates the entire sediment column from the sediment-water interface to the underlying basement to depths of > 75 m. At North Pond, a topographic depression filled with sediment and surrounded by steep basaltic outcrops, O2 penetrates deeply into the sediment (~ 30 m) until it eventually becomes depleted. O2 also diffuses upward into the sediment from seawater circulating within the young crust underlying the sediment, resulting in a deep oxic layer several meters above the basalt. Despite low organic carbon contents microbial cells persist throughout the entire sediment column within the SPG (> 75 m) and at North Pond, albeit at low abundances. We explored the nature of the subsurface microbial communities by extracting intact cells from large volumes of sediment obtained from drill cores of the two expeditions. By using CARD-FiSH, amplicon (16s rRNA) and metagenome sequencing we shed light on the phylogenetic and functional diversity of the elusive communities residing in the deep oxic sediments of these two different areas. Given the global extent of this oxic subsurface studies of the diversity and metabolic potential of its biome, together with the analyses of porewater geochemical and isotopic composition, are beginning to reveal its role in global biogeochemical cycles.

Chemical diagenesis, porosity reduction, and rock strength, IODP Site U1480: Influences on great earthquakes at shallow depths

NASA Astrophysics Data System (ADS)

Song, Insun; Milliken, Kitty; Dugan, Brandon; Bourlange, Sylvain; Colson, Tobias; Frederik, Marina; Jeppson, Tamara; Kuranaga, Mebae; Nair, Nisha; Henstock, Timothy

2017-04-01

International Ocean Discovery Program (IODP) Expedition 362 drilled two sites, U1480 and U1481, on the Indian oceanic plate ˜250 km west of the Sunda subduction zone to a maximum depth of 1500 meters below seafloor (mbsf). One of the primary objectives was to understand the mechanism of great earthquakes such as the 2004 Sumatra earthquake (Mw 9.0) which showed unexpectedly shallow megathrust slip by establishing the initial and evolving properties of the North Sumatran incoming sedimentary section. Core sampling and logging from the complete sedimentary section at U1480 indicates a distinct change in sedimentation rate from a slowly deposited pelagic system to a rapidly deposited submarine fan system at late Miocene. Following burial, sediments of the Nicobar Fan underwent compaction leading to porosity reduction from 66±9% near seafloor to ˜30% at the base of the sampled Nicobar Fan section (˜1250 mbsf), representing a normal consolidation behavior. Rock strength gradually increases with depth as the sediments are mechanically compacted. Below the fan (1250-1415 mbsf), the pelagic sediments are composed of tuffaceous, calcareous, and siliceous sediments/rocks and their porosity is dependent upon lithology more than upon depth. Tuffaceous materials exhibit high porosity ranging from ˜30-60%, even higher than that of overlying layers. However, porosity of most calcareous samples is lower than 20% at the same depth. The large variation in porosity depends on the degree of cementation, which in turn is controlled by grain assemblage composition and environmental conditions such as slow sedimentation rates and locally high temperatures related to igneous activity as documented by local igneous intrusives and extrusives. The minor cementation in tuffaceous sandy sediments has retained high porosity, but strengthened their skeleton so as to bear the overburden. The low porosity in calcareous rocks is considered to come from extensive cementation rather than mechanical compaction. The rock strengthening by mechanical compaction is dependent on effective stress, and does not facilitate storage of a large amount of elastic energy at shallow depth. However, chemical diagenesis (cementation) can lead to high strength that does not necessarily arise directly from burial. This chemical diagenesis potentially influences sediment strengthening that localizes great earthquakes at shallow depths.

Mechanical behavior in the Nankai inner accretionary prism, IODP Site C0002

NASA Astrophysics Data System (ADS)

Valdez, R. D., II; Saffer, D. M.

2017-12-01

Understanding the processes that control seismogenesis and stress state at subduction zones requires knowledge of fault zone and sediment physical and mechanical properties. As part of the International Ocean Discovery Program (IODP) Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE), Expedition 348 drilled into the Kumano forearc basin and underlying inner accretionary prism at Site C0002, located 35 km landward of the trench. One primary objective was to sample and characterize the mechanical behavior of the inner accretionary prism. Here we report on the frictional and unconfined compressive strength (UCS) of mudstone samples and a clay-rich shear zone recovered from 2182-2209 meters below sea floor (mbsf), determined from triaxial deformation tests at confining pressures from 1 to 7 MPa (UCS measurements on mudstones) and 36 MPa (strength of fault zone). Our results show that at a confining pressure of 1 MPa, the wall rock sediments fail at a peak differential stress of 9.1 MPa with a residual stress of 2.8 MPa. A clear peak and evolution to residual strength remains present at 7 MPa, and both the peak and residual strengths of the mudstones increases systematically with confining pressure. At a confining pressure of 36 MPa, the shear zone sediment yields at a differential stress of 25.2 MPa followed by strain-hardening to a maximum stress of 33.1 MPa. The shear zone is frictionally weaker than the surrounding mudstones, with a friction coefficient (μ) of 0.26-0.31, versus µ = 0.45 for the wall rock. The suite of tests defines a UCS for the mudstone of 7.9 MPa. Our friction data suggest that the inner wedge may be weaker than commonly assumed in applications of critical wedge theory to estimate the properties and conditions in accretionary prisms. One key implication is that for a given basal detachment friction coefficient, higher basal pore pressures (or lower wedge pore pressures) would be required to sustain observed taper angles. Additionally, the UCS we define is significantly lower than predicted by widely-adopted empirical relations between P wave velocity and UCS for shales (UCS of 15.5 MPa), suggesting that existing analyses of stress magnitudes from borehole breakout widths may overestimate horizontal stress magnitudes.

Undergraduate Collaborative Research: Distribution of Plant Wax Biomarkers in Miocene-age Sediments from the Bengal Fan (IODP Exp 354)

NASA Astrophysics Data System (ADS)

Cho, P. G.; Vidal, E.; Paek, J. H.; Borsook, A.; Lee, W.; Wu, M. S.; Ponton, C.; Galy, V.; Feakins, S. J.

2017-12-01

Our research aims to understand past climatic variability in the monsoon-influenced Ganges-Brahmaputra catchment as recorded by plant wax molecules exported and sequestered in the sediments of the Bengal Fan. Samples from the late Miocene were selected from cores retrieved by the IODP (International Ocean Discovery Program) Expedition 354 that recently drilled the central Bengal Fan along a transect at 8°N. Fan sedimentation includes sand, silt, and clay mostly derived from the Himalayan range via turbiditic transport within the Bengal fan. Sedimentation is highly episodic in the fan, but a transect of drilled sites provides a record of terrigenous sediment exported and buried over the last 20 million years. A team of researchers at the University of Southern California worked to collectively process 468 samples for compound specific biomarker identification and quantification. The samples derive from Site U1451 and U1455 ranging from 0 to 1097m depth (CSF-A). Total organic carbon ranges from 0.04-0.84%. To date, 300 samples have been solvent-extracted and prepared for plant wax analyses. Long chain n-alkanoic acids and n-alkanes were identified and quantified using GC-MS and GC-FID, respectively. In the samples quantified so far, we find ΣC24-34 n-alkanoic acid concentrations from 0.07-14.16 μg/g of dry sediment and ΣC25-35 n-alkanes from 0.04-4.61 μg/g. Concentrations of C30 n-alkanoic acid range from 0.01-1.92 μg/g of dry sediment and of C33 n-alkane from <0.01-0.65 μg/g. The molecular abundance distributions of both compound-classes were found to be diagnostic of a terrestrial higher plant source. Additionally, the molecular composition of the total lipid extract was analyzed at the Woods Hole Oceanographic Institution using a GC-TOF-MS. Overall, these extracts are dominated by plant-wax compounds and other diagnostic terrestrial molecules (e.g. plant terpenoids and sterols). The results from this effort contribute to a larger mission to reconstruct vegetation and climate change, over the past 20 million years in the core of the monsoon-influenced region, through compound-specific isotope analyses of the plant waxes extracted from these samples.

Indian National Gas Hydrate Program Expedition 01 report

USGS Publications Warehouse

Collett, Timothy S.; Riedel, M.; Boswell, R.; Presley, J.; Kumar, P.; Sathe, A.; Sethi, A.; Lall, M.V.; ,

2015-01-01

The Indian National Gas Hydrate Program Expedition 01 was designed to study the gas-hydrate occurrences off the Indian Peninsula and along the Andaman convergent margin with special emphasis on understanding the geologic and geochemical controls on the occurrence of gas hydrate in these two diverse settings. During Indian National Gas Hydrate Program Expedition 01, dedicated gas-hydrate coring, drilling, and downhole logging operations were conducted from 28 April 2006 to 19 August 2006.

The Family Expedition Program: Adventure Family Therapy in the Home As Well As in the Outdoors.

ERIC Educational Resources Information Center

Gass, Michael; Dolcino, Carina

The Family Expedition is a federally funded program designed to foster healthy changes in families with troubled adolescents through multifamily adventure therapy experiences. Each Family Expedition cycle is 4 months long, consisting of six multifamily sessions and three home visits. Each 90-minute home visit gives families time to focus on…

Scale dependence of in-situ permeability measurements in the Nankai accretionary prism: The role of fractures

NASA Astrophysics Data System (ADS)

Boutt, David F.; Saffer, Demian; Doan, Mai-Linh; Lin, Weiren; Ito, Takatoshi; Kano, Yasuyuki; Flemings, Peter; McNeill, Lisa C.; Byrne, Timothy; Hayman, Nicholas W.; Moe, Kyaw Thu

2012-04-01

Modeling studies suggest that fluid permeability is an important control on the maintenance and distribution of pore fluid pressures at subduction zones generated through tectonic loading. Yet, to date, few data are available to constrain permeability of these materials, at appropriate scales. During IODP Expedition 319, downhole measurements of permeability within the uppermost accretionary wedge offshore SW Japan were made using a dual-packer device to isolate 1 m sections of borehole at a depth of 1500 m below sea floor. Analyses of pressure transients using numerical models suggest a range of in-situ fluid permeabilities (5E-15-9E-17 m2). These values are significantly higher than those measured on core samples (2E-19 m2). Borehole imagery and cores suggests the presence of multiple open fractures at this depth of measurement. These observations suggest that open permeable natural fractures at modest fracture densities could be important contributors to overall prism permeability structure at these scales.

Subsurface metabolic potential on the Costa Rican Margin

NASA Astrophysics Data System (ADS)

Biddle, J.; Leon, Z. R.; Martino, A. J.; Bousses, K.; House, C. H.

2017-12-01

The distribution of archaea and bacteria and their associated metabolic abilities in the deep subseafloor are poorly understood. In order to explore this, we focused on samples from the Costa Rica margin IODP Expedition 334. The microbial community was analyzed via metagenomics in two different sites at multiple depths. At Site 1378, samples are from 2 meters below the sea floor (mbsf), 33 mbsf and 93 mbsf, and at Site 1379 from 22 mbsf to 45 mbsf. Whole community analysis of conserved gene markers in the metagenome show that the microbial community varies with depth, and drastically differs between the two geographically close sites. Thirty-two genomes were recovered from the metagenomic data with more than 30% completion. Archaea make 49% of all genomes recovered and over 90% of these recovered genomes belong to recently discovered and poorly characterized groups of Archaea. This study explored the relative dynamics of microbial communities in the deep biosphere and presents the metabolic potential of distinct subsurface biosphere archaeal groups.

Postglacial Fringing-Reef to Barrier-Reef conversion on Tahiti links Darwin's reef types

NASA Astrophysics Data System (ADS)

Blanchon, Paul; Granados-Corea, Marian; Abbey, Elizabeth; Braga, Juan C.; Braithwaite, Colin; Kennedy, David M.; Spencer, Tom; Webster, Jody M.; Woodroffe, Colin D.

2014-05-01

In 1842 Charles Darwin claimed that vertical growth on a subsiding foundation caused fringing reefs to transform into barrier reefs then atolls. Yet historically no transition between reef types has been discovered and they are widely considered to develop independently from antecedent foundations during glacio-eustatic sea-level rise. Here we reconstruct reef development from cores recovered by IODP Expedition 310 to Tahiti, and show that a fringing reef retreated upslope during postglacial sea-level rise and transformed into a barrier reef when it encountered a Pleistocene reef-flat platform. The reef became stranded on the platform edge, creating a lagoon that isolated it from coastal sediment and facilitated a switch to a faster-growing coral assemblage dominated by acroporids. The switch increased the reef's accretion rate, allowing it to keep pace with rising sea level, and transform into a barrier reef. This retreat mechanism not only links Darwin's reef types, but explains the re-occupation of reefs during Pleistocene glacio-eustacy.

Deep ocean research meets the special education classroom

NASA Astrophysics Data System (ADS)

Turner, A.; Turner, M.; Edwards, K. J.; Scientific Team Of Iodp Expedition 327

2010-12-01

The scientific activities carried out on board the JOIDES Resolution during IODP Expedition 327: Juan de Fuca Hydrogeology (summer 2010) are exciting to elementary-level students and provide an excellent opportunity to use that enthusiasm to teach concepts outlined in state-mandated curricula. This is especially important for special education classrooms where individualized education plans are implemented to bring students up to these standards when regular classrooms have failed to do so. Using concepts from drilling and coring to geobiology and sedimentology, we have developed cross-curricular lesson plans for elementary special education students with learning and cognitive disabilities. All lesson plans include hands-on, visual and auditory activities and are aimed at using students' natural interest in real research to drive home simple concepts like integers, geography, pressure and descriptive writing. Because special education classrooms more often than not include children with variable abilities in all subjects, the lesson plans developed in this project can be adapted for several levels so that every child in the classroom can participate.

Actinobacterial diversity across a marine transgression in the deep subsurface off Shimokita Peninsula, Japan

NASA Astrophysics Data System (ADS)

Harrison, B. K.; Bailey, J. V.

2013-12-01

Sediment horizons represent a significant - but not permanent - barrier to microbial transport. Cells commonly attach to mineral surfaces in unconsolidated sediments. However, by taxis, growth, or passive migration under advecting fluids, some portion of the microbial community may transgress sedimentary boundaries. Few studies have attempted to constrain such transport of community signatures in the marine subsurface and its potential impact on biogeography. Integrated Ocean Drilling Program (IODP) Expedition 337 off the Shimokita Peninsula recovered sediments over a greater than 1km interval representing a gradual decrease of terrestrial influence, from tidal to continental shelf depositional settings. This sequence represents a key opportunity to link subsurface microbial communities to lithological variability and investigate the permanence of community signatures characteristic of distinct depositional regimes. The phylogenetic connectivity between marine and terrestrially-influenced deposits may demonstrate to what degree sediments offer a substantial barrier to cell transport in the subsurface. Previous work has demonstrated that the Actinobacterial phylum is broadly distributed in marine sediments (Maldonado et al., 2005), present and active in the deep subsurface (Orsi et al., 2013), and that marine and terrestrial lineages may potentially be distinguished by 16S rRNA gene sequencing (e.g. Prieto-Davó et al., 2013). We report on Actinobacteria-specific 16S rRNA gene diversity recovered between 1370 and 2642 mbsf with high-throughput sequencing using the Illumina MiSeq platform, as well as selective assembly and analysis of environmental clone libraries.

Glacial discharge, upwelling and productivity off the Adélie coast, Antarctica: results from a 171 m Holocene sediment core from IODP Expedition 318

NASA Astrophysics Data System (ADS)

Newton, Kate; Bendle, James; McKay, Robert; Albot, Anya; Moossen, Heiko; Seki, Osamu; Willmott, Veronica; Schouten, Stefan; Riesselman, Christina; Dunbar, Robert

2016-04-01

Antarctica's coastal oceans play a vital role in controlling both the global carbon cycle and climate change, through variations in primary production, ocean stratification and ice melt. Yet, the Southern Ocean remains the least studied region on Earth with respect to Holocene climate variability. The few Antarctic proximal marine sedimentary records available tend to be short, low resolution, and discontinuous. However, sediments recovered from the Adélie drift during IODP Expedition 318 present a new opportunity to study East Antarctic Holocene climatic evolution, at a resolution that facilitates direct comparison with ice-cores. A 171m core of Holocene laminated diatom ooze was recovered from site U1357, representing continuous Holocene accumulation in a climatically-sensitive coastal polynya. We present results of biomarker analyses (TEX86-L and compound specific fatty acid delta-D and delta-13C, and sterol delta-D) and grain size from throughout the Holocene, revealing the complexities of this climatically sensitive environment. Carbon isotopes are interpreted predominantly as a productivity signal via CO2 drawdown, whilst hydrogen isotopes reflect inputs of isotopically-depleted glacial meltwater from the large Mertz glacier tongue and other proximal glaciers. Both upwelling, as shown by TEX86-L and grain size, and glacial meltwater inputs, indicated by biomarker delta-D, appear to have an important control on productivity on various time scales. The latter may be forced by warm subsurface temperatures through basal melting of the Mertz glacier tongue, indicating both direct and indirect effects of upwelling on productivity. The post-glacial, Early Holocene appears to be characterized by a highly variable system, due to both strong upwelling and meltwater inputs, followed by a more stable and highly productive Middle Holocene under a warmer climate. During the Late Holocene, characterized by a sea-ice expansion, temperature-induced sea-ice melt may have become a more important control on productivity. Millennial and centennial-scale isotopic excursions are also superimposed on the long-term trend. Productivity in particularly appears to follow some cyclicity, similar to that identified in other Antarctic productivity records, which may indicate a sensitivity of the environment to solar activity. Notably, a cyclicity of 2.3 ka is significant throughout the delta-13C record, closely resembling the previously recognised 'Hallstattzeit' solar cycle. Despite the strong importance of local forcing factors on the polynya system, our data suggest that, globally recognised, rapid climate changes are recorded in the site U1357 record.

The early diagenetic and PETROphysical behaviour of recent cold-water CARbonate mounds in Deep Environments (PETROCARDE)

NASA Astrophysics Data System (ADS)

Foubert, Anneleen; Pirlet, Hans; Thierens, Mieke; de Mol, Ben; Henriet, Jean-Pierre; Swennen, Rudy

2010-05-01

Sub-recent cold-water carbonate mounds localized in deeper slope settings on the Atlantic continental margins cannot be any longer neglected in the study of carbonate systems. They clearly play a major role in the dynamics of mixed siliciclastic-carbonate and/or carbonate-dominated continental slopes. Carbonate accumulation rates of cold-water carbonate mounds are about 4 to 12 % of the carbonate accumulation rates of tropical shallow-water reefs but exceed the carbonate accumulation rates of their slope settings by a factor of 4 to 12 (Titschack et al., 2009). These findings emphasize the importance of these carbonate factories as carbonate niches on the continental margins. The primary environmental architecture of such carbonate bodies is well-characterized. However, despite proven evidences of early diagenesis overprinting the primary environmental record (e.g. aragonite dissolution) (Foubert & Henriet, 2009), the extent of early diagenetic and biogeochemical processes shaping the petrophysical nature of mounds is until now not yet fully understood. Understanding (1) the functioning of a carbonate mound as biogeochemical reactor triggering early diagenetic processes and (2) the impact of early diagenesis on the petrophysical behaviour of a carbonate mound in space and through time are necessary (vital) for the reliable prediction of potential late diagenetic processes. Approaching the fossil carbonate mound record, through a profound study of recent carbonate bodies is innovative and will help to better understand processes observed in the fossil mound world (such as cementation, brecciation, fracturing, etc…). In this study, the 155-m high Challenger mound (Porcupine Seabight, SW of Ireland), drilled during IODP Expedition 307 aboard the R/V Joides Resolution (Foubert & Henriet, 2009), and mounds from the Gulf of Cadiz (Moroccan margin) will be discussed in terms of early diagenetic processes and petrophysical behaviour. Early differential diagenesis overprints the primary environmental signals in Challenger mound, with extensive coral dissolution and the genesis of small-scaled semi-lithified layers in the Ca-rich intervals. The low cementation rates compared to the extensive dissolution patterns can be explained by an open-system diagenetic model. Moreover, Pirlet et al. (2009) emphasizes the occurrence of gypsum and dolomite in another mound system (Mound Perseverance) in Porcupine Seabight, which might be also related with fluid oxidation events in a semi-open diagenetic system. Along the Moroccan margins, fluid seepage and fluxes in pore water transport affect the development of mound structures, enhancing extensive cold-water coral dissolution and precipitation of diagenetic minerals such as dolomite, calcite, pyrite, etc. (Foubert et al., 2008). Recent carbonate mounds provide indeed an excellent opportunity to study early diagenetic processes in carbonate systems without the complications of burial and/or later meteoric diagenesis. References Foubert, A. and Henriet, J.P. (2009) Nature and Significance of the Recent Carbonate Mound Record: The Mound Challenger Code. Lecture Notes in Earth Sciences, Vol. 126. Springer, 298 pp. ISBN: 978-3-642-00289-2. Pirlet, H., Wehrmann, L., Brunner, B., Frank, N., Dewanckele, J., Van Rooij, D., Foubert, A., Swennen, R., Naudts, L., Boone, M., Cnudde, V. and Henriet, J.P. (2009) Diagenetic formation of gypsum and dolomite in a cold-water coral mound in the Porcupine Seabight, off Ireland. Sedimentology. doi: 10.1111/j.1365-3091.2009.01119.x. Titschack, J., Thierens, M., Dorschel, B., Schulbert, C., Freiwald, A., Kano, A., Takashima, C., Kawagoe, N., Li, X. and the IODP Expedition 307 Scientific Party (2009) Carbonate budget of a cold-water coral mound (Challenger Mound, IODP Exp. 307). Marine Geology, 259, 36-46.

Raman counting of heavy minerals in turbidites: Indus Fan, IODP Expedition 355

NASA Astrophysics Data System (ADS)

Andò, Sergio

2017-04-01

Raman spectroscopy is an innovative tool with tremendous potential. Thorny long-standing problems that cannot be solved confidently with a polarizing microscope alone, such as the determination of opaque heavy minerals or of detrital grains as small as a few microns, can finally be addressed. Heavy-mineral species commonly found in sediments convey specific information on the genesis of their source rocks and are therefore crucial in provenance diagnoses and palaeotectonic reconstructions. A high-resolution mineralogical study of Indus Fan turbiditic sediments cored during IODP Expedition 355 (Arabian Sea Monsoon) in the Laxmi Basin was carried out to investigate and quantify the different compositional signatures of sand and silt fractions. Silt and sand in turbidite deposits recovered at IODP Sites U1456 and U1457 were chosen as the best natural archive for this source-to-sink study. An integrated mineralogical dataset was obtained by coupling traditional and innovative single-grain heavy-mineral analyses. Reliable quantitative results even in the medium to fine silt classes, which represent the dominant sediment sizes encountered in the recovered cores, were obtained by point-counting of single grains under the microscope assisted by Micro-Raman spectroscopy. Preliminary data from the studied turbidites document rich and diverse heavy-mineral assemblages in both sand and silty-sand fractions. Multiple varietal studies of amphibole, epidote and garnet varieties, representing the dominant heavy-mineral trial in orogenic detritus derived from collided ranges such as the Himalaya, were performed to highlight the wide unexplored potential of Raman spectroscopy when applied to provenance studies. Discriminating within the isomorphous series of garnets is possible, and diverse pyralspite and ugrandite garnets are distinguished by the position of characteristic peaks found at high frequencies and caused by Si-O stretching modes (873-880 cm-1 in ugrandites, 907-926 cm-1 in pyralspites; Bersani et al., 2009; Andò et al., 2009). Raman discrimination of amphibole varieties is also possible and the diagnostic position and shape of the more intense OH stretching bands (frequencies between 3600 and 3700 cm-1) are particularly helpful (Vezzoli et al., 2016). Raman discrimination of epidote-group minerals was tackled by using a new data set of the characteristic vibrational modes in the high-frequency region to facilitate distinction from other silicates and distinguish different varieties. A protocol to separate heavy minerals from the silt fraction, starting from a few grams of sediments only, was developed at the Laboratory for Provenance Studies of Milano-Bicocca. An appropriate data base of Raman spectra of detrital minerals is essential to apply this method routinely in future provenance studies of deep-sea turbidites. Such a new methodological approach plays a potentially key role to differentiate among the diverse Himalayan versus Indian Peninsular sources of detritus and opens up a new frontier for future studies of the largely unexplored deep-marine sedimentary record. Cited references S. Andò, D. Bersani, P. Vignola, E. Garzanti, 2009. Raman spectroscopy as an effective tool for high-resolution heavy-mineral analysis: examples from major Himalayan and Alpine fluvio-deltaic systems. Spectrochimica Acta Part A 73, 3, 450-455. D. Bersani, S. Andò, P. Vignola, G. Moltifiori, I.G. Marino, P.P. Lottici, V. Diella, 2009. Micro-Raman spectroscopy as a routine tool for garnet analysis. Spectrochimica Acta Part A 73, 3, 484-491. G. Vezzoli, E. Garzanti, M. Limonta, S. Andò, S. Yang, 2016. Erosion patterns in the Changjiang (Yangtze River) catchment revealed by bulk-sample versus single-mineral provenance budgets. Geomorphology 261, 177-192.

The Neogene equatorial Pacific: A view from 2009 IODP drilling on Expedition 320/321. (Invited)

NASA Astrophysics Data System (ADS)

Lyle, M. W.; Shackford, J.; Holbourn, A. E.; Tian, J.; Raffi, I.; Pälike, H.; Nishi, H.

2013-12-01

The equatorial Pacific responds strongly to global climate and is a source of ENSO, the largest global decadal climate oscillation. Equatorial Pacific circulation and upwelling result from global atmospheric circulation patterns so it is unsurprising that oceanographic changes in the equatorial Pacific reverberate globally. IODP expedition 320/321 (Pacific Equatorial Age Transect) drilled 8 sites to reconstruct a 50-million-year record of ocean change for the equatorial Pacific. The resulting record, when spliced together, will resolve orbital variations through most of the Cenozoic. All sedimentary sequences have now been scanned by XRF, so that biogeochemical changes through the Cenozoic can be studied. Here we report data from IODP Sites U1335, U1336, U1337, and U1338, the Neogene part of the PEAT megasplice. Sediments of the Neogene equatorial Pacific are primarily biogenic carbonates, with about 15% biogenic silica tests and 5% assorted other components, including clays. Typically, highest sediment deposition occurs when plate tectonic movement carries a drill site underneath the equatorial zone, indicating that equatorial upwelling and high productivity have been consistent features of the Neogene equatorial Pacific. Sedimentation rates become significantly slower and dissolution of both biogenic carbonates and silica are more pronounced when sites are beyond 3° in latitude away from the equator, as biogenic sediment production drops but dissolution does not. The differences between equatorial and off-equator sites allow assessment of productivity vs dissolution as drivers of the sediment record. Carbonate dissolution can also be assessed by a ratio of XRF-estimated carbonate to dissolution resistant biogenic residue, like barite. There is a common stratigraphy of carbonate variation in the Neogene equatorial Pacific, as proposed by earlier work from DSDP Leg 85 and ODP Leg 138. The new Exp 320/321 drilling extends the high-resolution record from ~0-5 Ma covered by Leg 138 studies to the full Neogene. Productivity events, like those in the late Miocene biogenic bloom interval (~5-7 Ma), are marked by carbonate percent lows at sites near the equator where diatom production outstrips increased production by carbonate producers. Away from the equator, there is little sign of the events in the percentage data because carbonate production increases in step with biogenic silica production at lower productivity increases. The middle-late Miocene carbonate crash interval (12-8 Ma) is marked by enhanced deposition of mat-forming diatioms, but highest deposition of bio-SiO2 is at the convergence of equatorial currents at 2°N, not at the equator. It is still unclear to what extent productivity shapes the events versus dissolution. Other productivity events can now be associated with middle Miocene Mi3-Mi4 glaciations. Dissolution events are also found, like the early Miocene ';lavender' event at 17 Ma. Surprisingly, peak dissolution is not associated with the peak warmth of the Miocene climatic optimum, but with an abrupt early warming that predates the warm interval. The dissolution event also predates possible volatile release from Columbia River flood basalts, indicating that complex changes in circulation and ocean carbon content must have occurred then. Understanding the timing will ultimately help to decipher the role of the carbon cycle in climate change.

Geochemistry of Sediment from IODP Expeditions 322 and 333: Terrigenous Provenance, Dispersed Ash, and the Nankai 'Subduction Factory'

NASA Astrophysics Data System (ADS)

Scudder, R.; Murray, R. W.; Schindlbeck, J.; Kutterolf, S.

2013-12-01

Terrigenous material and volcanic ash play important roles in the IODP Seismogenic Zone and 'Subduction Factory' initiatives. Particularly relevant to these projects are studies of geochemical budgets including how fluids within subducting sediment will be affected by hydration/dehydration reactions. Of great importance is the volcanic component, which occurs both as discrete ash layers and as ash dispersed throughout the sediment column and their related altered products in the down-going plate. Based on bulk sedimentary geochemical studies of IODP Sites C0011 and C0012 drilled during Expeditions 322 and 333, we will show the importance of dispersed ash to the Nankai subduction zone and document important changes in terrigenous provenance to these locations. The major elemental characteristics of the hemipelagic mudstones are remarkably consistent both downcore and between Site C0011 and Site C0012. For example, the average Si/Al ratio at both sites C0011 and C0012 is 3.3 × 0.2. This is observed in other key major elemental indicators as well (e.g., Fe2O3). Alkali elements, Trace elements and REEs exhibit greater downcore variability while remaining consistent between the sites. Ternary diagrams such as La-Th-Sc and Sc-Cr-Th as well as other geochemical plots (i.e., Sm/Al vs. Th/Al) show that Site C0011 and Site C0012 are fairly clustered, derived primarily from a continental arc source, and that distal sources to the sediment are important in addition to a modest and varying component from the proximal Izu-Bonin Island Arc. Multivariate statistical treatments are further being applied to the datasets from these sites to allow a better determination of the number of sources that make up the bulk sediment (and their provenance). Q-mode Factor Analysis was performed in order to determine the composition of potential end member contributions to these sites. The multivariate statistics indicate Site C0011 and C0012 each have 4-5 end members that explain 98% of the total variance in the data. These factors include those with very high SiO2, some with intermediate SiO2, and carbonate components. Applying these results in conjunction with Total Inversion, a linear regression technique, will allow us to determine the compositional variation of these end members. The potential mineralogical implications of these sources, contributing different amounts and species of magmatic minerals to the sediment, will also be presented. In addition we will examine the relationship between the source(s) of the discrete ash layers to the provenance of the dispersed ash component. Shipboard visual studies of the discrete ash layers identified at least two broad types of ash present at each site. Electron microprobe analysis of individual glass shards from ash layers at Sites 322 and 333 confirms the presence of two types of ash, the majority of the ashes are rhyolitic, while the rest are andesitic to dacitic in composition. Additionally, shipboard smear slide analysis noted a sharp gradient of glass alteration in ash layers at the Unit IA/IB boundary at Site C0011. Further work will determine how these discrete ash layers relate to the composition of the dispersed ash particularly in this section.

Trends in utilization of FDA expedited drug development and approval programs, 1987-2014: cohort study.

PubMed

Kesselheim, Aaron S; Wang, Bo; Franklin, Jessica M; Darrow, Jonathan J

2015-09-23

To evaluate the use of special expedited development and review pathways at the US Food and Drug Administration over the past two decades. Cohort study. FDA approved novel therapeutics between 1987 and 2014. Publicly available sources provided each drug's year of approval, their innovativeness (first in class versus not first in class), World Health Organization Anatomic Therapeutic Classification, and which (if any) of the FDA's four primary expedited development and review programs or designations were associated with each drug: orphan drug, fast track, accelerated approval, and priority review. Logistic regression models evaluated trends in the proportion of drugs associated with each of the four expedited development and review programs. To evaluate the number of programs associated with each approved drug over time, Poisson models were employed, with the number of programs as the dependent variable and a linear term for year of approval. The difference in trends was compared between drugs that were first in class and those that were not. The FDA approved 774 drugs during the study period, with one third representing first in class agents. Priority review (43%) was the most prevalent of the four programs, with accelerated approval (9%) the least common. There was a significant increase of 2.6% per year in the number of expedited review and approval programs granted to each newly approved agent (incidence rate ratio 1.026, 95% confidence interval 1.017 to 1.035, P<0.001), and a 2.4% increase in the proportion of drugs associated with at least one such program (odds ratio 1.024, 95% confidence interval 1.006 to 1.043, P=0.009). Driving this trend was an increase in the proportion of approved, non-first in class drugs associated with at least one program for drugs (P=0.03 for interaction). In the past two decades, drugs newly approved by the FDA have been associated with an increasing number of expedited development or review programs. Though expedited programs should be strictly limited to drugs providing noticeable clinical advances, this trend is being driven by drugs that are not first in class and thus potentially less innovative. © Kesselheim et al 2015.

ISS Expedition 42 Crew Profiles - Version 01

NASA Image and Video Library

2014-11-14

Narrated program with biographical information about ISS Expedition 42 crewmembers Terry Virts, Samantha Cristoforetti and Anton Shjaplerov. The program covers the crewmember's career including childhood photographs; footage from previous missions; and interview sound bites.

Porosity and Mineralogy Control on the Thermal Properties of Sediments in Off-Shimokita Deep-Water Coal Bed Basin

NASA Astrophysics Data System (ADS)

Tanikawa, W.; Tadai, O.; Morita, S.; Lin, W.; Yamada, Y.; Sanada, Y.; Moe, K.; Kubo, Y.; Inagaki, F.

2014-12-01

Heat transport properties such as thermal conductivity, heat capacity, and thermal diffusivity are significant parameters that influence on geothermal process in sedimentary basins at depth. We measured the thermal properties of sediment core samples at off-Shimokita basin obtained from the IODP Expedition 337 and Expedition CK06-06 in D/V Chikyu shakedown cruise. Overall, thermal conductivity and thermal diffusivity increased with depth and heat capacity decreased with depth, although the data was highly scattered at the depth of approximately 2000 meters below sea floor, where coal-layers were formed. The increase of thermal conductivity is mainly explained by the porosity reduction of sediment by the consolidation during sedimentation. The highly variation of the thermal conductivity at the same core section is probably caused by the various lithological rocks formed at the same section. Coal shows the lowest thermal conductivity of 0.4 Wm-1K-1, and the calcite cemented sandstone/siltstone shows highest conductivity around 3 Wm-1K-1. The thermal diffusivity and heat capacity are influenced by the porosity and lithological contrast as well. The relationship between thermal conductivity and porosity in this site is well explained by the mixed-law model of Maxwell or geometric mean. One dimensional temperature-depth profile at Site C0020 in Expedition 337 estimated from measured physical properties and radiative heat production data shows regression of thermal gradient with depth. Surface heat flow value was evaluated as 29~30 mWm-2, and the value is consistent with the heat flow data near this site. Our results suggest that increase of thermal conductivity with depth significantly controls on temperature profile at depth of basin. If we assume constant thermal conductivity or constant geothermal gradient, we might overestimate temperature at depth, which might cause big error to predict the heat transport or hydrocarbon formation in deepwater sedimentary basins.

Geochronology and Geochemistry of Zircons from the IODP Site U1437 in the Rear of the Izu-Bonin Volcanic Arc

NASA Astrophysics Data System (ADS)

Andrews, G. D.; Schmitt, A. K.; Busby, C. J.; Brown, S. R.

2015-12-01

Zircons recovered from International Ocean Discovery Program Expedition 350 Site U1437 (31°47.390'N, 139°01.580'E) in the Izu-Bonin arc were analyzed by SIMS to constrain their age (U/Pb geochronology) and geochemistry (trace elements, δ18O); LA-ICP-MS ɛHf analyses are pending. Seven intervals were dated successfully: six tuffs and lapilli-tuffs between 680.99 and 1722.46 m below sea floor (mbsf) and a single peperitic rhyolitic intrusion at 1388.86 - 1390.07 mbsf. Thirty-two intervals which underwent mineral separation lacked zircon, or yielded zircon much older than age expectations for U1437. Geochronology results from separated zircons confirm and extend the shipboard age model to 1360.77 mbsf where Late Miocene (Tortonian) submarine volcanic rocks (11.3 ±0.7 Ma; n = 17) were sampled. In-situ measurement of zircons associated with magnetite crystals in the rhyolite intrusion yield an age of 13.6 ±1.7 Ma (n = 9). Zircon U contents are low (typically <300 ppm), with trace element ratios characteristic of oceanic lithosphere and near-mantle δ18O values (4-6 ‰). Individual Miocene zircon crystals are difficult to distinguish by age alone from those in the drilling mud (sepiolite) used during Expedition 350; the sepiolite is quarried by IMV Nevada in the Amargosa Valley. Our analysis of thirty-three zircons from the sepiolite finds that they have a broad and varied age distribution (2 - 2033 Ma) with a prominent peak at 12-14 Ma, bimodal δ18O values (peaks at 5-5.5 and 6.5-7.5 ‰), and dominantly continental trace element signatures. Three zircons from U1437 are tentatively identified as sepiolite-derived, but a single Eocene grain (51.7 ±2.4 Ma) recovered from 1722.46 mbsf has an age unlike those in the sepiolite, and potentially is genuinely xenocrystic. The majority of U1437 zircons thus crystallized from evolved melts lacking continental characteristics, although thermal and compositional conditions conducive for zircon crystallization appear to have been rarely attained.

Early-middle Eocene transition in calcareous nannofossil assemblages at IODP Site U1410 (Southeast Newfoundland Ridge, NW Atlantic)

NASA Astrophysics Data System (ADS)

Cappelli, Carlotta; Agnini, Claudia; Yamamoto, Yuhji

2017-04-01

The early-middle Eocene interval documents the shift from the warmest greenhouse conditions occurred during the Early Eocene Climatic Optimum (EECO, 52-50 Ma) to the beginning of the cooling phase which led to the Oligocene icehouse regime. This important transition is well expressed as a reversal in the global oxygen and carbonate isotope trends (Zachos et al., 2001). Moreover, this interval was a time of remarkable transformation in the marine biosphere. Communities of calcareous nannoplankton, marine calcifying algae at the base of the oceans food chain, experienced transient and permanent profound changes. Calcareous nannofossil are regarded as remarkable tools both in biostratigraphy and paleoecology, with several taxa that show different responses to changes in physical parameters of surface waters. Here, we aim to document calcareous nannoplankton assemblage changes across the early-middle Eocene transition, in order to upset the biostratigraphic framework and to increase comprehension of how phytoplankton communities responded to paleoenvironmental changes at that time. The sedimentary successions recovered at IODP Site U1410 (Exp. 342; 41˚ 19.6987'N; 49˚ 10.1995'W, Norris et al., 2012) on the Southeast Newfoundland Ridge (NW Atlantic) offer an expanded record of the early-middle Eocene interval that is marked by an increase in accumulation rate related to sedimentation of clay-rich nannofossil oozes. Quantitative analysis of calcareous nannofossil assemblages was conducted, encompassing calcareous nannofossil Zones NP12 -NP15 or CNE4-CNE10 (Martini, 1971; Agnini et al., 2014). The study interval records the appearance and proliferation of Noelaerhabdaceae family (i.e, Reticulofenestra/Dictyococcites group), which can be considered one of the most significant shifts in the assemblage structure of the Paleogene. This change was probably favored by modifications in surface water chemistry. The middle Eocene clay-rich sediments contain well preserved nannofossils, making this Site suitable for a comprehensive taxonomic revision of Nannotetrina and Chiasmolithus. Biohorizons related to species belonging to these two genera are used to mark middle Eocene biozone boundary, a better characterization of their taxonomy would thus improve their reliability as biostratigraphic tools. Furthermore, during the early middle Eocene a new evolutionary lineage, which includes S. kempii - S. perpendicularis- S. furcatholitoides morph. A - S. cuniculus - S. furcatholitoides morph. B occurred among sphenoliths. This plexus is characterized by progressive morphological changes which, if correctly identify, will allow for a very detailed subdivision of this interval. Even more interestingly, we would assess if there is any relationship between this evolutionary trend and the surrounding abiotic conditions. Agnini, C., Fornaciari, E., Raffi, I., Catanzariti, R., Pälike, H., Backman, J., and Rio, D., Newslett. Stratigr., 47, 131-181 (2014). Martini E., in: Farinacci, A. (Ed.), Proceedings 2nd International Conference Planktonic Microfossils Roma: Rome (Ed. Tecnosci.) 2, 739-785 (1971). Norris R.D., Wilson P.A., Blum P. and the IODP Expedition 342 Scientists, Proceedings of the Integrated Ocean Drilling Program, 342, 1-148 (2012). Zachos J., Pagani M., Sloan L., Thomas E., Billups K., Science, 292, 686-693 (2001).

Development of a glacially dominated shelf-slope-fan system in tectonically active southeast Alaska: Results of IODP Expedition 341 core-log-seismic integrated studies at glacial cycle resolution

NASA Astrophysics Data System (ADS)

Gulick, Sean; Jaeger, John; Mix, Alan; Swartz, John; Worthington, Lindsay; Reece, Robert

2014-05-01

Collision of the Yakutat microplate with North American formed the St. Elias Mountains in coastal Gulf of Alaska. While the tectonic driver for orogenesis has been ongoing since the Miocene, results from the Integrated Ocean Drilling Program Expedition 341 suggests that direct climatic perturbation of active orogenesis through glacial erosion is non-linear. Geophysical studies of the glaciated continental margin, slope, and adjacent deep-sea Surveyor Fan allow examination of the glaciated orogen from source to sink. Using high-resolution and crustal-scale seismic data and through comparison with other glaciated margins, we can identify key diagnostic seismic morphologies and facies indicative of glacial proximity and sediment routing. Expedition drilling results calibrated these images suggesting a timeline for initial advances of the Cordilleran ice sheet related glacial systems onto the shelf and a further timeline for the development of ice streams that reach the shelf edge. Comparisons can be made within this single margin between evolution of the tectonic-glacial system where erosion and sediment transport are occurring within a fold and thrust belt versus on a more stable shelf region. Onshore the Bering-Bagley glacial system in the west flows across the Yakataga fold and thrust belt, allowing examination of whether glacial erosion can cause tectonic feedbacks, whereas offshore the Bering-Bagley system interacts with the Pamplona Zone thrusts in a region of significant sediment accommodation. Results from Expedition 341 imply that timing of glacial advance to the shelf edge in this region may be driven by the necessity of filling up the accommodation through aggradation followed by progradation and thus is autogenic. In contrast the Malaspina-Hubbard glacial system to the east encountered significantly less accommodation and more directly responded to climatic forcing including showing outer shelf glacial occupation since the mid-Pleistocene transition-MPT to 100 kyr glacial-interglacial cycles. Examination of the sink for both of these systems, which includes the Surveyor Fan and Aleutian Trench wedge, demonstrates a clear climatic driver for sediment flux to the deep sea. The first appearance of ice-rafted debris at our distal drill site closely approximates the start of the Pleistocene and a doubling of sediment accumulation accompanies the MPT. Converting sediment volumes just within the deep-sea sinks back to erosion rates in the orogen and correlating with changes in exhumation rates from thermochronology demonstrates a lack of accelerated tectonic response to the intensification of Northern Hemisphere glaciations at the start of the Pleistocene but increased shortening and exhumation of sediments at the MPT. The form of tectonic response differs between out-of-sequence thrusting or antiformal stacking within the fold and thrust belt to the west and a near vertical advection of material in a tectonic aneurysm in the core of the orogen to the east.

IODP-USIO: Employment: TAMU/TAMRF

Science.gov Websites

crime data collected or reported. In compliance with the Clery Act, Texas A&M University is required Security Report is available from the Texas A&M University Police Department web site. About the IODP

Variations of marine pore water salinity and chlorinity in Gulf of Alaska sediments (IODP Expedition 341)

NASA Astrophysics Data System (ADS)

März, Christian; Mix, Alan C.; McClymont, Erin; Nakamura, Atsunori; Berbel, Glaucia; Gulick, Sean; Jaeger, John; Schneider (LeVay), Leah

2014-05-01

Pore waters of marine sediments usually have salinities and chlorinities similar to the overlying sea water, ranging around 34-35 psu (Practical Salinity Units) and around 550 mM Cl-, respectively. This is because these parameters are conservative in the sense that they do not significantly participate in biogeochemical cycles. However, pore water studies carried out in the frame of the International Ocean Discovery Program (IODP) and its predecessors have shown that salinities and chlorinities of marine pore waters can substantially deviate from the modern bottom water composition in a number of environmental settings, and various processes have been suggested to explain these phenomena. Also during the recent IODP Expedition 341 that drilled five sites in the Gulf of Alaska (Northeast Pacific Ocean) from the deep Surveyor Fan across the continental slope to the glaciomarine shelf deposits, several occurrences of pore waters with salinities and chlorinities significantly different from respective bottom waters were encountered during shipboard analyses. At the pelagic Sites U1417 and U1418 (~4,200 and ~3,700 m water depth, respectively), salinity and chlorinity maxima occur around 20-50 m sediment depth, but values gradually decrease with increasing drilling depths (down to 30 psu in ~600 m sediment depth). While the pore water freshening at depth is most likely an effect of clay mineral dehydration due to increasing burial depth, the shallow salinity and chlorinity maxima are interpreted as relicts of more saline bottom waters that existed in the North Pacific during the Last Glacial Maximum (Adkins et al., 2002). In contrast, the glaciomarine slope and shelf deposits at Site U1419 to U1421 (~200 to 1,000 m water depth) are characterised by unexpectedly low salinitiy and chlorinity values (as low as 16 psu and 295 mM Cl-, respectively) already in very shallow sediment depths (~10 m), and their records do not show systematic trends with sediment depth. Freshening of pore waters in continental margin settings has been reported in association with dissociating gas hydrate deposits (Hesse, 2003), but neither seismic profiles nor sediment records showed any indications for the presence of gas hydrates at the Gulf of Alaska sites. An alternative and intriguing explanation for these almost brackish waters in the glaciomarine shelf and slope deposits is the presence of glacial meltwater that could either be "fossil" (stored in the glaciomarine sediments since the last glacial termination) or "recent" (i.e., actively flowing from currently melting glaciers of the St. Elias Mountain Range along permeable layers within the shelf deposits). As these relatively fresh waters are found at three distinct drill sites, it can be assumed that they are distributed all along the Gulf of Alaska shelf and slope, and similar findings have been reported at other glaciated continental margins, e.g., off East Greenland (DeFoor et al., 2011) and Antarctica (Mann and Gieskes, 1975; Chambers, 1991; Lu et al., 2010). While a recent review has highlighted the importance of fresh and brackish water reservoirs in continental shelf deposits worldwide (Post et al., 2013), we suggest that climatic and depositional processes affecting glaciated continental margins (e.g., the release of huge amounts of fresh water from ice sheets and glaciers during glacial terminations, and the rapid deposition of unconsolidated sediments on the adjacent shelf) are particularly favourable for the storage and/or flow of meltwater below the present sea floor. Adkins JF, McIntyre K, Schrag DP (2002) The salinity, temperature, and d18O of the glacial deep ocean. Science 298, 1769-1773. Chambers SR (1991) Solute distributions and stable isotope chemistry of interstitial waters from Prydz Bay, Antarctica. Proceedings of the Ocean Drilling Program 119, 375-392. DeFoor W, Person M, Larsen HC, Lizarralde D, Cohen D, Dugam B (2011) Ice sheet-derived submarine groundwater discharge on Greenland's continental shelf. Water Resources Research 47, W07549. Hesse R (2003) Pore water anomalies of submarine gas-hydrate zones as tool to assess hydrate abundance and distribution in the subsurface: What have we learned in the past decade? Earth-Science Reviews 61, 149-179. Lu Z, Rickaby REM, Wellner J, Georg B, Charnley N, Anderson JB, Hensen C (2010) Pore fluid modeling approach to identify recent meltwater signals on the West Antarctic Peninsula. Geochemistry, Geophysics, Geosystems 11, doi: 10.1029/2009GC002949. Mann R, Gieskes JM (1975) Interstitial water studies, Leg 28. Deep Sea Drilling Project Initial Reports 28, 805-814. Post VEA, Groen J, Kooi H, Person M, Ge S, Edmunds M (2013) Offshore fresh groundwater reserves as a global phenomenon. Nature 504, 71-78.

Gas-hydrate-bearing sand reservoir systems in the offshore of India: Results of the India National Gas Hydrate Program Expedition 02

USGS Publications Warehouse

Kumar, P.; Collett, Timothy S.; Vishwanath, K.; Shukla, K.M.; Nagalingam, J.; Lall, M.V.; Yamada, Y; Schultheiss, P.; Holland, M.

2016-01-01

The India National Gas Hydrate Program Expedition 02 (NGHP-02) was conducted from 3-March-2015 to 28-July-2015 off the eastern coast of India using the deepwater drilling vessel Chikyu. The primary goal of this expedition was to explore for highly saturated gas hydrate occurrences in sand reservoirs that would become targets for future production tests. The first two months of the expedition were dedicated to logging-whiledrilling (LWD) operations, with a total of 25 holes drilled and logged. The next three months were dedicated to coring operations at 10 of the most promising sites. With a total of five months of continuous field operations, the expedition was the most comprehensive dedicated gas hydrate investigation ever undertaken.

Scientific networking to address the causes, timing, emplacement mechanisms, and consequences of the Messinian Salinity Crisis

NASA Astrophysics Data System (ADS)

Camerlenghi, Angelo; Lofi, Johanna; Aloisi, Vanni; Flecker, Rachel

2017-04-01

The origin of the Mediterranean salt giant is linked to an extraordinary event in the geological history of the Mediterranean region, commonly referred to as the Messinian Salinity Crisis (MSC). After 45 years of intense yet disunited research efforts, the international scientific community at large faces a unique opportunity to access the deep and marginal basins Messinian depositional successions in the Mediterranean through scientific drilling, namely through the Integrated Ocean Discovery Program (IODP) and the International Continental Drilling Program (ICDP). Scientific activity to promote scientific drilling offshore and onshore is in progress under the broad umbrella of the Uncovering a Salt Giant' IODP Multi-Platform Drilling proposal, that has generated the Deep-Sea Records of the Messinian Salinity Crisis (DREAM) site-specific pre-proposal for riserless drilling on Messinian marginal basins and the related ICDP-IODP amphibious initiative Investigating Miocene Mediterranean- Atlantic gateway exchange (IMMAGE). Scientific networking has begun to establish a broad cross-disciplinary research community embracing geology, geophysics, geochemistry, microbiology, and paleoclimatology. Formal networking activities represent an opportunity for the scientific community to share objectives, data, expertise and tools with industry since there is considerable interest in oil and gas exploration, and consequent hazards, targeting the Mediterranean's deep salt deposits. With the acronym MEDSALT, we have established two networks working in close cooperation: (1) COST Action CA15103 Uncovering the Mediterranean salt giant (MEDSALT) (https://medsalt.eu/) is a 4-year long network established in May 2016 comprising scientific institutions from 28 states. This COST Action will provide an opportunity to develop further our knowledge of salt rock formation addressing four overarching scientific questions: a) What are the causes, timing and emplacement mechanisms of the Mediterranean salt giant? b) What are the factors responsible for and the socio-economic consequences of early salt deformation and fluid flow across and out of the halite layer? c) Do salt giants promote the development of a phylogenetically diverse and exceptionally active deep biosphere? d) What are the mechanisms underlying the spectacular vertical motions inside basins and their margins? (2) ANR Project 'Uncovering the Mediterranean Salt Giant' (MEDSALT) aims at establishing networking action to prepare an Integrated Ocean Discovery Program (IODP) full proposal to drill the Mediterranean Salt Giant with the R/V JOIDES Resolution. This 18-month long network consists of a core group of 22 scientists from 10 countries working in close cooperation with the brother COST Action MEDSALT. These inter-sectorial and multinational cooperation networks comprise a critical mass of both experienced and early-career researchers from Europe and beyond. The goal will be achieved through capacity building, researchers' mobility, skills development, knowledge exchange and scientific networking.

40Ar/39Ar dating and zircon chronochemistry for the Izu-Bonin rear arc, IODP site U1437

NASA Astrophysics Data System (ADS)

Schmitt, A. K.; Konrad, K.; Andrews, G. D.; Horie, K.; Brown, S. R.; Koppers, A. A. P.; Busby, C.; Tamura, Y.

2016-12-01

The scientific objective of IODP Expedition 350 drilling at Site U1437 (31°47.390'N, 139°01.580'E) was to reveal the "missing half of the subduction factory": the rear arc of a long-lived intraoceanic subduction zone. Site U1437 lies in a 50 km long and 20 km wide volcano-bounded basin, 90 km west of the Izu arc front, and is the only IODP site drilled in the rear arc. The Izu rear arc is dominated by Miocene basaltic to dacitic seamount chains, which strike at a high angle to the arc front. Radiometric dating targeted a single igneous unit (1390 mbsf), and fine to coarse volcaniclastic units for which we present zircon and 40Ar/39Ar (hornblende, plagioclase, and groundmass) age determinations. All zircons analyzed as grain separates were screened for contamination from drill-mud (Andrews et al., 2016) by analyzing trace elements and, where material was available, O and Hf isotope compositions. Igneous Unit 1 is a rhyolite sheet and yielded concordant in-situ and crystal separate U-Pb zircon ages (13.7±0.3 Ma; MSWD = 1.3; n = 40 spots), whereas the 40Ar/39Ar hornblende plateau age (12.9±0.3; MSWD = 1.1; n = 9 steps) is slightly younger, possibly reflecting pre-eruptive zircon crystallization, or alteration of hornblende. U-Pb zircon and 40Ar/39Ar plateau ages from samples above igneous Unit 1 are concordant with biostratigraphic and paleomagnetic ages (available to 1300 mbsf), but plagioclase and groundmass samples below 1300 m become younger with depth, hinting at post-depositional alteration. A single zircon from 1600 mbsf yielded a U-Pb age of 15.4±1.8 Ma; its trace element composition resembles other igneous zircons from U1437, and is tentatively interpreted as a Middle Miocene age for the lowermost lithostratigraphic unit VII. Oxygen and Hf isotopic values of igneous zircon indicate mantle origins, with some influence of assimilation of hydrothermally altered oceanic crust evident in sub-mantle oxygen isotopic compositions. Lessons from site U1437 are that integrated chronochemistry is essential for achieving accurate age models in oceanic drilling. Reference: Andrews, G. D., Schmitt, A. K., Busby, C. J., Brown, S. R., Blum, P., & Harvey, J. (2016). Age and compositional data of zircon from sepiolite drilling mud to identify contamination of ocean drilling samples. G3. doi: 10.1002/2016GC006397.

The Evolution of the Campi Flegrei caldera (Italy): High- and low-frequency multichannel 2.5D seismic surveying for an amphibian IODP/ICDP drilling approach

NASA Astrophysics Data System (ADS)

Steinmann, Lena; Spiess, Volkhard; Sacchi, Marco

2016-04-01

Caldera-forming eruptions are considered as one of the most catastrophic natural events to affect the Earth's surface and human society. The half-submerged Campi Flegrei caldera, located in southern Italy, belongs to the world's most active calderas and, thus, has received particular attention in scientific communities and governmental institutions. Therefore, it has also become subject to a joint approach in the IODP and ICDP programmes. Despite ample research, no scientific consensus regarding the formation history of the Campi Flegrei caldera has been reached yet. So far, it is still under debate whether the Campi Flegrei caldera was formed by only one ignimbritic eruption, namely the Neapolitan Yellow Tuff (NYT) eruption at 15 ka or, if it is a nested-caldera system related to the NYT and the Campanian Ignimbrite (CI) eruption at 39 ka. In the last decades, the Campi Flegrei caldera has been characterized by short-term episodes of unrest involving considerable ground deformation (uplift and subsidence of several meters), seismicity and increased temperature at fumaroles. Furthermore, long-term deformation can be observed in the central part of the caldera with uplift rates of several tens of meters within a few thousand years. Recently, it has been proposed that the long-term deformation may be related to caldera resurgence, while short-term uplift episodes are probably triggered by the injection of magmatic fluids into a shallow hydrothermal system at ~2 km depth. However, both long-term and short term uplift could be interpreted as eruption precursor, thereby posing high-concern for a future eruption, which would expose more than 1.5 million people living in the surroundings of the volcanic district to extreme volcanic risks. During a joint Italian-German research expedition in 2008, a semi-3D grid (100-150 m profile spacing) of high-frequency (up to 1000 Hz) multichannel seismic data were acquired to support both the ongoing onshore ICDP and a proposed offshore IODP drilling campaign. These data are of outstanding quality and high vertical resolution (~1 m), however, limited by their low signal penetration of ~200 m below seafloor. Hence, only the shallow structures of the Campi Flegrei caldera could be imaged and, consequently, the interpretation was mainly focused on the evolution of the Campi Flegrei caldera since the NYT eruption at 15 ka. Nonetheless, the data also show first evidence for a collapse prior the NYT eruption, supporting the existence of a nested-caldera system formed by collapses related to both the CI and NYT eruptions. Detailed imaging of the upper 2 km - target of the IODP/ICDP drilling campaigns - will be provided through an additional semi-3D (50 m profile spacing) low-frequency (20-200 Hz) multichannel seismic survey collected in February 2016. Preliminary results from a combination of both low- and high-frequency seismic surveys will be presented on (1) deeper-seated collapse structures related to the CI eruption, (2) the extent of the caldera fill, and (3) the hypothesized shallow hydrothermal system.

A Thick, Deformed Sedimentary Wedge in an Erosional Subduction Zone, Southern Costa Rica

NASA Astrophysics Data System (ADS)

Silver, E. A.; Kluesner, J. W.; Edwards, J. H.; Vannucchi, P.

2014-12-01

A paradigm of erosional subduction zones is that the lower part of the wedge is composed of strong, crystalline basement (Clift and Vannucchi, Rev. Geophys., 42, RG2001, 2004). The CRISP 3D seismic reflection study of the southern part of the Costa Rica subduction zone shows quite the opposite. Here the slope is underlain by a series of fault-cored anticlines, with faults dipping both landward and seaward that root into the plate boundary. Deformation intensity increases with depth, and young, near-surface deformation follows that of the deeper structures but with basin inversions indicating a dynamic evolution (Edwards et al., this meeting). Fold wavelength increases landward, consistent with the folding of a landward-thickening wedge. Offscraping in accretion is minimal because incoming sediments on the lower plate are very thin. Within the wedge, thrust faulting dominates at depth in the wedge, whereas normal faulting dominates close to the surface, possibly reflecting uplift of the deforming anticlines. Normal faults form a mesh of NNW and ENE-trending structures, whereas thrust faults are oriented approximately parallel to the dominant fold orientation, which in turn follows the direction of roughness on the subducting plate. Rapid subduction erosion just prior to 2 Ma is inferred from IODP Expedition 334 (Vannucchi et al., 2013, Geology, 49:995-998). Crystalline basement may have been largely removed from the slope region during this rapid erosional event, and the modern wedge may consist of rapidly redeposited material (Expedition 344 Scientists, 2013) that has been undergoing deformation since its inception, producing a structure quite different from that expected of an eroding subduction zone.

A tale of phenocrysts: trace element contents of boninites and forearc basalts from IODP Expedition 352

NASA Astrophysics Data System (ADS)

Chapman, T.; Clarke, G. L.; Reagan, M. K.; Sakuyama, T.; Godard, M.; Shervais, J. W.; Prytulak, J.; Shimizu, K.; Nelson, W. R.; Heaton, D. E.; Whattam, S. A.; Li, H.; Pearce, J. A.

2016-12-01

The Izu-Bonin Mariana (IBM) forearc represents an ideal location to study the dynamics of subduction initiation and to reveal the volcanic sequences appropriate to assess ophiolite origins. The volcanic stratigraphy recovered on Expedition 352 illustrates an abrupt shift from forearc basalt (FAB) to boninite magmatism, with limited transitional rock types, as observed from submersible and previous drill work in the Izu-Bonin and Mariana sections. The transition represents a change from decompression melting to fluxed melting of the mantle wedge. The volcanic stratigraphy has several distinct boninite chemical evolution trends (basaltic boninite, low- and high-silica boninite). Mineral assemblages and phenocryst trace element compositions vary throughout the volcanic sequence providing an opportunity to explore more completely boninite and FAB transitions and petrogenesis. FABs are characterised by early plagioclase crystallization and HREE enriched clinopyroxene with high Ti contents. Basaltic boninite and some low-silica boninite lavas have overlapping REE concentrations consistent with early plagioclase growth preceded by clinopyroxene. In contrast, textures and HREE depleted concentrations of clinopyroxene in high-silica boninite imply late plagioclase growth relative to olivine and orthopyroxene. Variations in mineral compositions and paragenesis in boninites reflect changes in magma compositions and a progressive depletion of mantle sources over time. This is illustrated via key incompatible and compatible trace element ratios and concentrations (e.g. Zr/Ti & V or Cr). The transition from FAB to low-Si boninite was subtle in terms of mineral modes, but was more evident in terms of the phase and lava compositions.

42 CFR 438.410 - Expedited resolution of appeals.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 42 Public Health 4 2010-10-01 2010-10-01 false Expedited resolution of appeals. 438.410 Section 438.410 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL ASSISTANCE PROGRAMS MANAGED CARE Grievance System § 438.410 Expedited...

Biogeochemical cycling in the Bering Sea over the onset of major Northern Hemisphere Glaciation

NASA Astrophysics Data System (ADS)

Swann, George E. A.; Snelling, Andrea M.; Pike, Jennifer

2016-09-01

The Bering Sea is one of the most biologically productive regions in the marine system and plays a key role in regulating the flow of waters to the Arctic Ocean and into the subarctic North Pacific Ocean. Cores from Integrated Ocean Drilling Program (IODP) Expedition 323 to the Bering Sea provide the first opportunity to obtain reconstructions from the region that extend back to the Pliocene. Previous research at Bowers Ridge, south Bering Sea, has revealed stable levels of siliceous productivity over the onset of major Northern Hemisphere Glaciation (NHG) (circa 2.85-2.73 Ma). However, diatom silica isotope records of oxygen (δ18Odiatom) and silicon (δ30Sidiatom) presented here demonstrate that this interval was associated with a progressive increase in the supply of silicic acid to the region, superimposed on shift to a more dynamic environment characterized by colder temperatures and increased sea ice. This concluded at 2.58 Ma with a sharp increase in diatom productivity, further increases in photic zone nutrient availability and a permanent shift to colder sea surface conditions. These transitions are suggested to reflect a gradually more intense nutrient leakage from the subarctic northwest Pacific Ocean, with increases in productivity further aided by increased sea ice- and wind-driven mixing in the Bering Sea. In suggesting a linkage in biogeochemical cycling between the south Bering Sea and subarctic Northwest Pacific Ocean, mainly via the Kamchatka Strait, this work highlights the need to consider the interconnectivity of these two systems when future reconstructions are carried out in the region.

Chemical compositions and precipitation timing of basement carbonate vein from fossil spreading ridge of South China Sea

NASA Astrophysics Data System (ADS)

Ding, W.; Chen, Y.

2016-12-01

Eighteen calcium carbonate veins within the igneous basement recovered close to the fossil spreading ridge of the South China Sea during the Integrated Ocean Drilling Program (IODP) Expedition 349 were investigated. These carbonates are of primarily either calcite or aragonite, or some mixed aragonite and calcite, with rarely ankerite. The chemical (Ca, Mg, Sr, Mn, Fe) contents and isotopic (87Sr/86Sr, δ18O, δ18C) compositions of the veins were determined to study the evolving chemistry of hydrothermal fluids and to constrain the timing of vein formation. The carbonate δ18O values range from -5.0 to -0.2 ‰ PDB, indicating these are typical low temperature basement carbonates. Chemical analyses show distinct Mg/Ca and Sr/Ca ratios for aragonite and calcite. 87Sr/86Sr ratios show negative correlations with both the depth and δ18O-calculated formation temperature, and are independent of mineralogy with both aragonite and calcite, indicating more geochemically evolved carbonated have precipitated from warmer fluids. The hightest 87Sr/86Sr ratios of vein samples at each drill site are believed to reflect the contemporaneous seawater compositions when carbonates precipitated. No unambiguous precipitation ages can be constrained by correlating 87Sr/86Sr ratios with the global seawater Sr isotope evolution. However, based on correlations of vein chemical composition with depth and formation temperature, as well as the Neogene post-spreading magmatism, we hypothesize 10 Ma is a particular time favoring the formation of carbonate veins in our study area.

Plume versus plate origin for the Shatsky Rise oceanic plateau (NW Pacific): Insights from Nd, Pb and Hf isotopes

NASA Astrophysics Data System (ADS)

Heydolph, Ken; Murphy, David T.; Geldmacher, Jörg; Romanova, Irina V.; Greene, Andrew; Hoernle, Kaj; Weis, Dominique; Mahoney, John

2014-07-01

Shatsky Rise, an early Cretaceous igneous oceanic plateau in the NW Pacific, comprises characteristics that could be attributed to either formation by shallow, plate tectonic-controlled processes or to an origin by a mantle plume (head). The plateau was drilled during Integrated Ocean Drilling Program (IODP) Expedition 324. Complementary to a recent trace element study (Sano et al., 2012) this work presents Nd, Pb and Hf isotope data of recovered lava samples cored from the three major volcanic edifices of the Shatsky Rise. Whereas lavas from the oldest edifice yield fairly uniform compositions, a wider isotopic spread is found for lavas erupted on the younger parts of the plateau, suggesting that the Shatsky magma source became more heterogeneous with time. At least three isotopically distinct components can be identified in the magma source: 1) a volumetrically and spatially most common, moderately depleted component of similar composition to modern East Pacific Ridge basalt but with low 3He/4He, 2) an isotopically very depleted component which could represent local, early Cretaceous (entrained) depleted upper mantle, and 3) an isotopically enriched component, indicating the presence of (recycled) continental material in the magma source. The majority of analyzed Shatsky lavas, however, possess Nd-Hf-Pb isotope compositions consistent with a derivation from an early depleted, non-chondritic reservoir. By comparing these results with petrological and trace element data of mafic volcanic rock samples from all three massifs (Tamu, Ori, Shirshov), we discuss the origin of Shatsky Rise magmatism and evaluate the possible involvement of a mantle plume (head).

Paleomagnetic inclination and declination from three-component borehole magnetometer data—New insights from logging in the Louisville seamounts

NASA Astrophysics Data System (ADS)

Ehmann, S.; Hördt, A.; Leven, M.; Virgil, C.

2015-01-01

We carried out measurements of the magnetic field vector at two sites during Integrated Ocean Drilling Program (IODP) Expedition 330 to the Louisville Seamount Chain. The aim was to impose constraints on the magnetization direction and to contribute to the reconstruction of possible hot spot motion. The measurements were conducted using the Göttingen Borehole Magnetometer (GBM). It comprises three fiber optic gyros (FOG) that can be used to reorient the magnetic field data. To improve accuracy, we are using a new algorithm that combines FOG data and data of two inclinometers. As can be evaluated by comparing downlog and uplog of the measurements, the three-dimensional magnetic field data obtained is of good quality. An interpretation of the magnetic field data using a state of the art method based on horizontal layers yields results inconsistent with measurements of the natural remanent magnetization (NRM) of drill core samples. In the following, we define the magnetization from the horizontal layer as apparent magnetization and develop a new interpretation method based on dipping layers. Our method includes a new approximate forward modeling algorithm and considerably improves the consistency of the borehole measurements and the NRM data. We show that a priori information about the geometry of a layer is required to constrain the inclination and declination of magnetization. Especially the azimuth of a layer and the declination of magnetization cannot be determined separately. Using azimuth and layer dip information from borehole images, we obtain constraints on inclination and declination for one particular layer.

The nature and function of microbial enzymes in subsurface marine sediments

NASA Astrophysics Data System (ADS)

Steen, A. D.; Schmidt, J.

2016-02-01

Isotopic and genomic evidence indicates that marine sediments contain populations of active heterotrophic microorganisms which appear to metabolize old, detrital, apparently recalcitrant organic matter. In surface communities, heterotrophs use extracellular enzymes to access complex organic matter. In subsurface sediments, in which microbial doubling times can be on the order of hundreds or thousands of years, it is not clear whether extracellular enzymes could remain stable and active long enough to constitute a 'profitable' stragtegy for accessing complex organic carbon. Here we present evidence that a wide range of extracellular enzyme are active in subsurface sediments from two different environments: the White Oak River, NC, and deep (up to 80 m) sediments of the Baltic Sea Basin recovered from IODP Expedition 347. In the White Oak River, enzymes from deeper sediments appear to be better-adapted to highly-degraded organic matter than enzymes from surface sediments. In the Baltic Sea, preliminary data suggest that enzymes related to nitrogen acquisition are preferentially expressed. By characterizing the extracellular enzymes present in marine sediments, we hope to achieve a better understanding of the mechanisms that control sedimentary organic matter remineralization and preservation.

Opening of the South China Sea and Upwelling of the Hainan Plume

NASA Astrophysics Data System (ADS)

Yu, Mengming; Yan, Yi; Huang, Chi-Yue; Zhang, Xinchang; Tian, Zhixian; Chen, Wen-Huang; Santosh, M.

2018-03-01

Opening of the South China Sea and upwelling of the Hainan Plume are among the most challenging issues related to the tectonic evolution of East Asia. However, when and how the Hainan Plume affected the opening of the South China Sea remains unclear. Here we investigate the geochemical and isotopic features of the 25 Ma mid-ocean ridge basalt (MORB) in the Kenting Mélange, southern Taiwan, 16 Ma MORB drilled by the IODP Expedition 349, and 9 Ma ocean island basalt-type dredged seamount basalt. The 25 Ma MORBs reveal a less metasomatic depleted MORB mantle-like source. In contrast, the Miocene samples record progressive mantle enrichment and possibly signal the contribution of the Hainan Plume. We speculate that MORBs of the South China Sea which could have recorded plume-ridge source mixing perhaps appear since 23.8 Ma. On the contrary, the Paleocene-Eocene ocean island basalt-type intraplate volcanism of the South China continental margin is correlated to decompression melting of a passively upwelling fertile asthenosphere due to continental rifting.

Tuffaceous Mud is a Volumetrically Important Volcaniclastic Facies of Submarine Arc Volcanism and Record of Climate Change

NASA Astrophysics Data System (ADS)

Gill, J. B.; Bongiolo, E. M.; Miyazaki, T.; Hamelin, C.; Jutzeler, M.; DeBari, S.; Jonas, A.-S.; Vaglarov, B. S.; Nascimento, L. S.; Yakavonis, M.

2018-04-01

The inorganic portion of tuffaceous mud and mudstone in an oceanic island arc can be mostly volcanic in origin. Consequently, a large volume of submarine volcaniclastic material is as extremely fine-grained as products of subaerial eruptions (<100 µm). Using results of IODP Expedition 350 in the Izu rear arc, we show that such material can accumulate at high rates (12-20 cm/k.y.) within 13 km of the nearest seamount summit and scores of km behind the volcanic front. The geochemistry of bulk, acid-leached mud, and its discrete vitriclasts, shows that >75% of the mud is volcanic, and that most of it was derived from proximal rear arc volcanic sources. It faithfully preserves integrated igneous geochemical information about arc evolution in much the same way that terrigenous shales track the evolution of continental crust. In addition, their high sedimentation rate enables high resolution study of climate cycles, including the effects of Pleistocene glaciation on the behavior of the Kuroshio Current in the Shikoku Basin south of Japan.

Links between Iron Fertilization and Biological Pump Efficiency in the Bering Sea Over the Last 3.5 Myrs

NASA Astrophysics Data System (ADS)

Bartoli, G. L.; Studer, A. S.; Martinez Garcia, A.; Haug, G. H.

2011-12-01

The Bering Sea is one of the major sink of atmospheric CO2 today, due to the efficiency of its biological pump, despite a limitation by iron. Here we present records of iron fertilization by aeolian dust deposition (n-alkane concentration) and phytoplankton nutrient consumption (diatom-bound δ15N record) over the last 3.5 Myrs in the southwestern Bering Sea at Site U1341 drilled during IODP Expedition 323. During the Pliocene Epoch, when sea surface temperatures were 3-4°C warmer than today and sea-ice cover was reduced, the biological pump efficiency during glacial and interglacial stages was minimal, similar to Quaternary interglacials. Low iron deposition and weaker surface water stratification resulting in higher nutrient inputs contributed to reduce the biological pump efficiency until 1.5 Ma. After the intensification of glacial conditions in the Bering Sea and the increase in sea-ice cover and iron inputs, the biological pump efficiency progressively increased, reaching values similar to Quaternary glacials after the mid-Pleistocene transition.

Intermittent carbonate sedimentation in the equatoral Indian Ocean: fluctuations of the Eocene CCD?

NASA Astrophysics Data System (ADS)

Mitchison, F.; Kachovich, S.; Backman, J.; Pike, J.

2017-12-01

IODP Expedition 362 recently drilled from the sea floor to oceanic basement in the eastern equatorial Indian Ocean at Site U1480G (3°N, 91°E, water depth 4148 m). Beneath the thick ( 1250 m) predominantly siliciclastic Nicobar Fan succession, a condensed ( 10 m) middle Eocene pelagic interval displayed striking decimetre-scale banding, alternating between calcareous oozes and darker clays. We investigate whether deposition of the calcareous sediments was associated with periodic global carbonate accumulation events previously documented in the Equatorial Pacific and Atlantic Oceans, linked to oscillations of the carbonate compensation depth (CCD). We present high-resolution geochemical records (carbonate, organic carbon, bulk carbonate stable isotopes) and scanning electron microscope micro-element maps through several of the calcareous to clay transitions, as well as microfossil assemblages and new biostratigraphic constraints for the interval. Our data will reveal whether the banded sediments represent fluctuations of the CCD, and whether the CCD was likely responding to global (e.g. changes in pCO2) or local (e.g. local changes in calcareous plankton productivity) processes.

Chemical profiles along olivine crystallographic axes: a record of the melt-rock interaction sequence forming Hole U1309D Olivine-rich troctolites (Atlantis Massif, MAR, 30°N)

NASA Astrophysics Data System (ADS)

Ferrando, Carlotta; Godard, Marguerite; Ildefonse, Benoit; Rampone, Elisabetta

2017-04-01

The gabbroic section drilled at IODP Hole U1309D (Mid-Atlantic Ridge, IODP Expeditions 304, 305) comprises a whole range of modes from primitive olivine-rich troctolites to evolved gabbros. These series occur as discrete alternating intervals of variable composition and thickness at different depths. High MgO contents and a relatively large proportion of olivine-rich lithologies (up to 90% modal olivine) characterize this gabbroic section. Contacts between olivine-rich troctolites and neighboring coarse grained olivine gabbros are sharp, with the exception of the contacts between olivine-rich intervals and cross-cutting gabbroic veins, which are diffuse and characterized by progressive variations in plagioclase content. Olivine-rich troctolites are heterogeneously distributed along the borehole and show variable modal composition: centimeter to decimeter scale dunitic (90% olivine), troctolitic (enriched in plagioclase) and wehrlitic (enriched in clinopyroxene) domains were identified. Previous in-situ trace element geochemistry and crystallographic preferred orientation measurements of olivine-rich troctolites indicated that they record extensive melt impregnation of pre-existing olivine-rich material, either mantle rocks or dunitic cumulate. We performed a detailed multi-scale petro-structural and geochemical study on selected samples of well-preserved olivine-rich troctolites with the aim to unravel the sequence of re-equilibration processes and better constrain the local conditions driving the formation of these rocks. Processed EBSD maps show variable textures at single sample scale. All identified domains are characterized by coarse grained and deformed olivines, and small rounded undeformed olivines. Coarse grained and small rounded olivines have the same major and trace element compositions. Small olivines are interpreted as relicts after dissolution of coarse grained olivines. Clinopyroxene, plagioclase, and minor orthopyroxene are present as interstitial phases. Dunitic and troctolitic domains display different microstructural and geochemical signatures. Their mineral modal percentages and compositions are not correlated along typical trends of fractional crystallization. The dunitic domain has olivines showing lower Mg# (82-83, against 85-86 in troctolitic domain), higher Ni and Mn contents. In the dunitic domain olivine, plagioclase and clinopyroxene are more enriched in trace elements compared to those in the troctolitic domain. These compositions reveal reaction and re-equilibration processes of pre-existing mantle-derived olivine-rich rock with an infiltrating olivine-undersaturated MORB-type melt. Chemical traverses along principal crystallographic axes of olivine reveal flat cpxcore-cpxrim-olrim-olcore profiles for all major and trace elements with the exception of Ca and Y, which are modified due to late subsolidus re-equilibration. Flat profiles indicate either (i) slow olivine dissolution kinetics relative to equilibration of primary olivine with incoming melts or (ii) preservation of initial chemical signature and fast olivine dissolution kinetics. These two end-member scenarii are investigated using thermodynamic models to better constrain (dis-)equilibrium relationships between mineral phases and reactive percolation modeling to determine the contribution of advective and diffusive processes to local chemical signatures. Drouin, M., Godard, M., Ildefonse, B., Bruguier, O., Garrido, C.J. (2009): Geochemical and petrographic evidence for magmatic impregnation in the oceanic lithosphere at Atlantis Massif, Mid-Atlantic Ridge (IODP Hole U1309D, 30°N). Chem Geol 264, 71-88. Drouin, M., Ildefonse, B., Godard, M. (2010) A microstructural imprint of melt impregnation in slow-spread lithosphere: olivine-rich troctolites from the Atlantis Massif (Mid-Atlantic Ridge 30°N, IODP Hole U1309D). Geochem Geophys Geosyst 11:Q06003, doi:10.1029/2009GC002995. Godard, M., et al. (2009): Geochemistry of a long in-situ section of intrusive slow-spread oceanic lithosphere: Results from IODP Site U1309(Atlantis Massif, 30°N Mid-Atlantic- Ridge). Earth Planet. Sci. Lett. 279, 110-122, doi:10.1016/j.epsl.2008.12.034.

Initiation and development of slickenlined surfaces in clay-rich material of the Nankai Trough accretionary prism

NASA Astrophysics Data System (ADS)

Crespo-Blanc, Ana; Schleicher, Anja

2016-04-01

During the International Ocean Discovery Program (IODP) Expedition 348, which is part of the Nankai Trough Seismogenic Zone Experiment (stage 3), the drilling vessel Chikyu advanced the deep riser hole at Site C0002, located 80 km offshore of the Kii Peninsula (Japan), from a depth of 860 meters below sea floor (mbsf) to 3058.5 mbsf. Underlying the Kumano Basin sediments, the Nankai accretionary prism appears, below 975.5 mbsf. It accreted during Upper Miocene to Pliocene times and is formed mainly by turbiditic silty claystone with rarely observed sandstone intercalations. Cuttings from both the 1-4 mm and >4 mm size fractions were investigated, showing slickenlined surfaces and deformation bands together with carbonate veins throughout the entire section from 1045.5 until 3058.5 mbsf. A scaly fabric is increasingly observed below approximately 2400 mbsf. Clay-rich cuttings were selected at different depth for specific SEM-EDS analysis, in order to investigate the initiation and development of the slickenlined surfaces, from both a structural and mineralogical point of view. Two end-members of the slickenlined surface types were observed: a) isolated smooth and uniform planes, between 20 and 50 μm long, formed by single grains of smectite with marked lineations and frequently jagged boundaries and b) microfaults (longer than 100 μm) with sharp boundaries to the undeformed rock, formed by aggregates of illite and smectite and with a well-developed lineation. In transition between these two end-member types, planes that are apparently unconnected draw a single plane and show subparallel lineations. Concerning the orientation of the slickenlines, it seems to be coherent with that observed in an array of conjugated faults, i.e. all the slickenlines belong to the same plane, in turn sub-perpendicular to the intersection of conjugated planes. These observations suggest that the slickenlined surfaces initiated along single grains of smectite and that with increasing deformation, the planes coherently oriented connected all together until the formation of a mature slickenline surface (microfault). It must be stressed that the described geometry was observed at any depth and the same process of formation seem to be valid for the whole drilled section of the Nankai accretionary prism. Acknowledgements: This research used samples provided by IODP. Grants RNM-215 and 451 ("Junta de Andalucía", Spain) and CGL2013-46368-P ("Ministerio de Economía y Competitividad", Spain) supported this study.

Mud Gas Logging In A Deep Borehole: IODP Site C0002, Nankai Trough Accretionary Prism

NASA Astrophysics Data System (ADS)

Toczko, S.; Hammerschmidt, S.; Maeda, L.

2014-12-01

Mud logging, a tool in riser drilling, makes use of the essentially "closed-circuit" drilling mud flow between the drilling platform downhole to the bit and then back to the platform for analyses of gas from the formation in the drilling mud, cuttings from downhole, and a range of safety and operational parameters to monitor downhole drilling conditions. Scientific riser drilling, with coincident control over drilling mud, downhole pressure, and returning drilling mud analyses, has now been in use aboard the scientific riser drilling vessel Chikyu since 2009. International Ocean Discovery Program (IODP) Expedition 348, as part of the goal of reaching the plate boundary fault system near ~5000 mbsf, has now extended the deep riser hole (Hole C0002 N & P) to 3058.5 mbsf. The mud gas data discussed here are from two approximately parallel boreholes, one a kick-off from the other; 860-2329 mbsf (Hole C0002N) and 2163-3058 mbsf (Hole C0002P). An approximate overlap of 166 m between the holes allows for some slight depth comparison between the two holes. An additional 55 m overlap at the top of Hole C0002P exists where a 10-5/8-inch hole was cored, and then opened to 12-1/4-inch with logging while drilling (LWD) tools (Fig. 1). There are several fault zones revealed by LWD data, confirmed in one instance by coring. One of the defining formation characteristics of Holes C0002 N/P are the strongly dipping bedding planes, typically exceeding 60º. These fault zones and bedding planes can influence the methane/ethane concentrations found in the returning drilling mud. A focused comparison of free gas in drilling mud between one interval in Hole C0002 P, drilled first with a 10 5/8-inch coring bit and again with an 12 ¼-inch logging while drilling (LWD) bit is shown. Hole C0002N above this was cased all the way from the sea floor to the kick-off section. A fault interval (in pink) was identified from the recovered core section and from LWD resistivity and gamma. The plot of methane and ethane free gas (C1 and C2; ppmv) shows that the yield of free gas (primarily methane) was greater when the LWD bit returned to open the cored hole to a greater diameter. One possible explanation for this is the time delay between coring and LWD operations; approximately 3 days passed between the end of coring and the beginning of LWD (25-28 December 2013).

187Os/188Os of boninites from the Izu-Bonin-Mariana forearc, IODP Exp 352

NASA Astrophysics Data System (ADS)

Niles, D. E.; Nelson, W. R.; Reagan, M. K.; Pearce, J. A.; Godard, M.; Shervais, J. W.

2016-12-01

The Izu-Bonin-Mariana (IBM) subduction zone is an ideal laboratory in which to study the evolution of a subduction zone from its initiation to the development of modern-day arc volcanism. Boninite lavas were produced in the IBM forearc region during the early stages of subduction and are thought to have been generated by flux melting the previously depleted mantle wedge. Mariana forearc mantle peridotites record unradiogenic 187Os/188Os signatures (0.1193-0.1273) supporting the existence of variably depleted mantle in this region (Parkinson et al., 1998). In order to understand the connection between the regional mantle, slab-derived fluids, and the generation of boninites, Re-Os isotopic data were measured on subset of boninite-series lavas obtained during IODP Expedition 352. Preliminary age-corrected (48 Ma) 187Os/188Os isotopic data for boninite-series lavas (sites U1439C and U1442A) are unradiogenic to modestly radiogenic (0.1254-0.1390) compared to primitive mantle (0.1296), consistent with Os isotopic data from boninite sands from the Bonin Islands (0.1279-0.1382; Suzuki et al., 2011). The least radiogenic boninites have 187Os/188Os (< 0.1296) values consistent with average MORB mantle recorded globally by abyssal peridotites (0.1238 ± 0.0042; Rudnick & Walker, 2009). However, boninite lavas were not derived from the most refractory ancient mantle recorded by Mariana peridotites. Unradiogenic boninites generally have higher Os abundances (0.043-0.567 ppb), whereas more radiogenic boninites have low Os abundances (0.015-0.036). Due to their low Os abundances, the moderately radiogenic isotopic signatures may be the result of interaction with highly radiogenic seawater or incorporation of radiogenic sediment (e.g. Suzuki et al. 2011). However, the radiogenic values could also be the result of fluid flux from the subducting Pacific plate.

Post-Drilling Changes in Seabed Landscape and Megabenthos in a Deep-Sea Hydrothermal System, the Iheya North Field, Okinawa Trough

PubMed Central

Nakajima, Ryota; Yamamoto, Hiroyuki; Kawagucci, Shinsuke; Takaya, Yutaro; Nozaki, Tatsuo; Chen, Chong; Fujikura, Katsunori; Miwa, Tetsuya; Takai, Ken

2015-01-01

There has been an increasing interest in seafloor exploitation such as mineral mining in deep-sea hydrothermal fields, but the environmental impact of anthropogenic disturbance to the seafloor is poorly known. In this study, the effect of such anthropogenic disturbance by scientific drilling operations (IODP Expedition 331) on seabed landscape and megafaunal habitation was surveyed for over 3 years using remotely operated vehicle video observation in a deep-sea hydrothermal field, the Iheya North field, in the Okinawa Trough. We focused on observations from a particular drilling site (Site C0014) where the most dynamic change of landscape and megafaunal habitation was observed among the drilling sites of IODP Exp. 331. No visible hydrothermal fluid discharge had been observed at the sedimentary seafloor at Site C0014, where Calyptogena clam colonies were known for more than 10 years, before the drilling event. After drilling commenced, the original Calyptogena colonies were completely buried by the drilling deposits. Several months after the drilling, diffusing high-temperature hydrothermal fluid began to discharge from the sedimentary subseafloor in the area of over 20 m from the drill holes, ‘artificially’ creating a new hydrothermal vent habitat. Widespread microbial mats developed on the seafloor with the diffusing hydrothermal fluids and the galatheid crab Shinkaia crosnieri endemic to vents dominated the new vent community. The previously soft, sedimentary seafloor was hardened probably due to barite/gypsum mineralization or silicification, becoming rough and undulated with many fissures after the drilling operation. Although the effects of the drilling operation on seabed landscape and megafaunal composition are probably confined to an area of maximally 30 m from the drill holes, the newly established hydrothermal vent ecosystem has already lasted 2 years and is like to continue to exist until the fluid discharge ceases and thus the ecosystem in the area has been altered for long-term. PMID:25902075

Post-drilling changes in seabed landscape and megabenthos in a deep-sea hydrothermal system, the Iheya North field, Okinawa Trough.

PubMed

Nakajima, Ryota; Yamamoto, Hiroyuki; Kawagucci, Shinsuke; Takaya, Yutaro; Nozaki, Tatsuo; Chen, Chong; Fujikura, Katsunori; Miwa, Tetsuya; Takai, Ken

2015-01-01

There has been an increasing interest in seafloor exploitation such as mineral mining in deep-sea hydrothermal fields, but the environmental impact of anthropogenic disturbance to the seafloor is poorly known. In this study, the effect of such anthropogenic disturbance by scientific drilling operations (IODP Expedition 331) on seabed landscape and megafaunal habitation was surveyed for over 3 years using remotely operated vehicle video observation in a deep-sea hydrothermal field, the Iheya North field, in the Okinawa Trough. We focused on observations from a particular drilling site (Site C0014) where the most dynamic change of landscape and megafaunal habitation was observed among the drilling sites of IODP Exp. 331. No visible hydrothermal fluid discharge had been observed at the sedimentary seafloor at Site C0014, where Calyptogena clam colonies were known for more than 10 years, before the drilling event. After drilling commenced, the original Calyptogena colonies were completely buried by the drilling deposits. Several months after the drilling, diffusing high-temperature hydrothermal fluid began to discharge from the sedimentary subseafloor in the area of over 20 m from the drill holes, 'artificially' creating a new hydrothermal vent habitat. Widespread microbial mats developed on the seafloor with the diffusing hydrothermal fluids and the galatheid crab Shinkaia crosnieri endemic to vents dominated the new vent community. The previously soft, sedimentary seafloor was hardened probably due to barite/gypsum mineralization or silicification, becoming rough and undulated with many fissures after the drilling operation. Although the effects of the drilling operation on seabed landscape and megafaunal composition are probably confined to an area of maximally 30 m from the drill holes, the newly established hydrothermal vent ecosystem has already lasted 2 years and is like to continue to exist until the fluid discharge ceases and thus the ecosystem in the area has been altered for long-term.

Mediterranean Outflow Water during the late Pliocene: New stratigraphic constraints from micropaleontology and XRF core-scanning (IODP Expedition 339, Hole U1389E)

NASA Astrophysics Data System (ADS)

Grunert, Patrick; Balestra, Barbara; Flores, José-Abel; Garcia Gallardo, Ángela; Auer, Gerald; Röhl, Ulla; Piller, Werner E.

2015-04-01

IODP Hole U1389E, at present located in the lower core of the Mediterranean Outflow Water (MOW) at 640m water depth in the northern Gulf of Cadiz, represents a key-site for the understanding of changes in MOW contribution to the North Atlantic during the late Pliocene thermal optimum and the transition into the Pleistocene ice house climate. Zr/Al ratios of the recovered sediments as well as δ18O and Mg/Ca of benthic foraminifera imply major changes in MOW strength in the studied interval. However, to consider these data in a broader paleoceanographic and paleoclimatic context, a well-constrained age model is essential. New data from calcareous nannoplankton and XRF core-scanning suggest that the shipboard age model for the site has to be reconsidered as major changes in sedimentation rates have not been recognized in the original comparably low resolution data-sets. While the new, higher-resolution biostratigraphic data confirm the overall time frame of 2.6 to 3.6 Myrs, they also imply a potential sedimentary hiatus within the Pliocene thermal optimum and a significant increase in sedimentation rates thereafter. A distinct cyclic pattern is recognized in the CaCO3 and TOC contents as well as Ca/Ti ratios. Based on the estimated sedimentation rates these cycles are most likely linked to precessional forcing, resembling cyclic changes in riverine input from southern Spain recognized at several drill-sites at the northern shelf break. A detailed cyclostratigraphic analysis is currently in progress to confirm the precessional signal and to further constrain the duration of the sedimentary hiatus during the Pliocene thermal optimum. This study contributes to project P25831-N29 of the Austrian Science Fund (FWF) and is financially supported by grants of ECORD and the Max Kade Foundation.

Return to the Strangelove Ocean?: Preliminary results of carbon and oxygenisotope compositions of post-impact sediments, IODP Expedition 364 "Chicxulub Impact Crater"

NASA Astrophysics Data System (ADS)

Yamaguchi, K. E.; Ikehara, M.; Hayama, H.; Takiguchi, S.; Masuda, S.; Ogura, C.; Fujita, S.; Kurihara, E.; Matsumoto, T.; Oshio, S.; Ishihata, K.; Fuchizawa, Y.; Noda, H.; Sakurai, U.; Yamane, T.; Morgan, J. V.; Gulick, S. P. S.

2017-12-01

The Chicxulub crater in the northern Yucatan Peninsula, Mexico was formed by the asteroid impact at the Cretaceous-Paleogene boundary (66.0 Ma). In early 2016 the IODP Exp. 364 successfully drilled the materials from the topographic peak ring within the crater that was previously identified by seismological observations. A continuous core was recovered. The 112m-thick uppermost part of the continuous core (505.7-1334.7 mbsf) is post-impact sediments, including the PETM, that are mainly composed of carbonate with intercalation of siliciclastics and variable contents of organic carbon. More than 300 samples from the post-impact section were finely powdered for a variety of geochemical analysis. Here we report their carbon and oxygen isotope compositions of the carbonate fraction (mostly in the lower part of the analyzed section) and carbon and nitrogen isotope compositions of organic matter (mostly in the middle-upper part of the analyzed section). Isotope mass spectrometer Isoprime was used for the former analysis, and EA-irMS (elemental analyzer - isotope ratio mass spectrometer) was used for the latter analysis, both at CMCR, Kochi Univ. Depth profile of oxygen isotope compositions of carbonate fraction is variable and somewhat similar to those of Zachos et al. (2001; Science). Carbon isotope compositions of carbonate and organic carbon in the lower part of the analyzed section exhibit some excursions that could correspond to the hyperthemals in the early Paleogene. Their variable nitrogen isotope compositions reflect temporal changes in the style of biogeochemical cycles involving denitrification and nitrogen fixation. Coupled temporal changes in the carbon isotope compositions of organic and carbonate carbon immediately after the K-Pg boundary might support a Strangelove ocean (Kump, 1991; Geology), however high export production (Ba/Ti, nannoplankton and calcisphere blooms, high planktic foram richness, and diverse and abundant micro- and macrobenthic organisms) at the base of the Danian limestone cored during Exp. 364 contradict a Strangelove Ocean.

Greenhouse to Icehouse Antarctic Paleoclimate and Ice History from George V Land and Adélie Land Shelf Sediments

NASA Astrophysics Data System (ADS)

Williams, T.; Escutia, C.; De Santis, L.; O'Brien, P.; Pekar, S. F.; Brinkhuis, H.; Domack, E. W.

2013-12-01

Along the George V and Adélie Land continental shelf of East Antarctica, shallowly-buried strata contain a record of Antarctica's climate and ice history from the lush forests of the Eocene greenhouse to the dynamic ice sheet margins of the Neogene. Short piston cores and dredges have recovered Early Cretaceous and Eocene organic-rich sediment at the seabed, and in 2010, IODP Expedition 318 recovered earliest Oligocene and early Pliocene subglacial and proglacial diamictites. However, challenging ice and drilling conditions from the JOIDES Resolution on the shelf resulted in poor core recovery and sites had to be abandoned before the stratigraphic targets could be reached. Therefore, in a new IODP drilling proposal submitted earlier this year, we propose to use the MeBo sea bed drill for improved core recovery and easier access to the shelf, and drill a stratigraphic transect of shallow (~80m) holes. To investigate the evolution of the Antarctic ice sheet in this sector, we target strata above and below regional erosional and downlap surfaces to date and characterize major episodes of ice sheet advance and retreat. These direct records of ice extent on the shelf can be set in the context of Southern Ocean records of temperature, ice-rafted debris (IRD) and latitudinal fluctuations of the opal belt, and hence we can relate ice sheet evolution to paleoclimate conditions. Targets include possible late Eocene precursor glaciations, the Eocene/Oligocene boundary erosion surface, Oligocene and Miocene ice extents, and ice margin fluctuations in the Pliocene. At the Cretaceous and Eocene proposed sites, marine and terrestrial temperature proxies and palynological records will provide information on high-latitude paleoenvironments and pole-equator temperature gradients. Here we present existing data from the area and the proposed new drill sites. The ice and climate history of the George V and Adélie Land margin can provide warm-world scenarios to help understand ice sheet instability in analogous future warm climates.

Reconstructing initial Mediterranean Outflow from Benthic Foraminifera

NASA Astrophysics Data System (ADS)

Garcia Gallardo, A.; Grunert, P.; Voelker, A. H. L.; Mendes, I.; Piller, W. E.

2016-12-01

The onset of Mediterranean Outflow Water (MOW) takes place after the opening of the Gibraltar Strait (5.33 Ma). Its impact on oceanography and climate in the present is widely studied but its role in the early Pliocene is not well explored yet. Quantitative analysis of benthic foraminifera has been performed on sediment samples from the lower part of IODP Hole U1387C (IODP Expedition 339) in order to reconstruct paleoenvironmental changes during the late Miocene-early Pliocene. Micropaleontological records reveal a shift from reduced oxygenation in the late Miocene to a better ventilated setting during the early Pliocene likely related to the first evidence of Mediterranean-Atlantic exchange. Increased abundances of the functional benthic foraminiferal "elevated epifauna" group have been directly related to MOW in the Gulf of Cadiz since they are adapted to settle on substrates above the sediment surface to catch food particles from strong bottom currents (Schönfeld, 2002). In our study, the elevated epifauna is represented by Planulina ariminensis, Cibicides lobatulus and C. refulgens. However, our early Pliocene records reveal that peak abundances of C. lobatulus and C. refulgens are well correlated with allochthonous shelf taxa and grain-size maxima, suggesting downslope transport to deeper settings. To clarify this issue, stable isotope analyses (δ18O, δ13C) have been performed on shells of shelf dwellers, deep water taxa and elevated epifauna from Pliocene and present-day samples from the Iberian Margin. Preliminary results indicate that some elevated epifaunal elements have a broad bathymetric range and are not always autochthonous to deeper settings. In the early Pliocene Gulf of Cadiz, characterized by frequent turbidite deposition, P. ariminensis would thus remain the only reliable indicator of MOW. Schönfeld, J., 2002. A new benthic foraminiferal proxy for near-bottom current velocities in the Gulf of cadiz, Northeastern Atlantic Ocean. Deep-Sea Res I 49:1853-1875.

Improved Quaternary North Atlantic stratigraphy using relative paleointensity (RPI), oxygen isotopes, and magnetic excursions (Invited)

NASA Astrophysics Data System (ADS)

Channell, J. E.

2013-12-01

Improving the resolution of Quaternary marine stratigraphy is one of the major challenges in paleoceanography. IODP Expedition 303/306, and ODP Legs 162 and 172, have yielded multiple high-resolution records (mean sedimentation rates in the 7-20 cm/kyr range) of relative paleointensity (RPI) that are accompanied by oxygen isotope data and extend through much of the Quaternary. Tandem fit of RPI and oxygen isotope data to calibrated templates (LR04 and PISO), using the Match protocol, yields largely consistent stratigraphies, implying that both RPI and oxygen isotope data are dominated by regional/global signals. Based on the recent geomagnetic field, RPI can be expected to be a global signal (i.e. dominated by the axial dipole field) when recorded at sedimentation rates less than several decimeters/kyr. Magnetic susceptibility, on the other hand, is a local/regional lithologic signal, and therefore less useful for long-distance correlation. Magnetic excursions are directional phenomena and, when adequately recorded, are manifest as paired reversals in which the virtual geomagnetic poles (VGPs) reach high latitudes in the opposite hemisphere, and they occupy minima in RPI records. Reversed VGPs imply that excursions are attributable to the main axial dipole, and therefore provide global stratigraphy. The so-called Iceland Basin excursion is recorded at many IODP/ODP sites and lies at the MIS 6/7 boundary at ~188 ka, with a duration of 2-3 kyr. Other excursions in the Brunhes chron are less commonly recorded because their duration (perhaps <~1 kyr) requires sedimentation rates >20 cm/kyr to be adequately recorded. On the other hand, several excursions within the Matuyama Chron are more commonly recorded in North Atlantic drift sediments due to relatively elevated durations. With some notable exceptions (e.g. Iberian Margin), high quality RPI records from North Atlantic sediments, together with magnetic excursions, can be used in tandem with oxygen isotope data to strengthen Quaternary (North Atlantic) stratigraphy.

The US Food and Drug Administration's expedited approval programs: Evidentiary standards, regulatory trade-offs, and potential improvements.

PubMed

Wallach, Joshua D; Ross, Joseph S; Naci, Huseyin

2018-06-01

The US Food and Drug Administration has several regulatory programs and pathways to expedite the development and approval of therapeutic agents aimed at treating serious or life-debilitating conditions. A common feature of these programs is the regulatory flexibility, which allows for a customized approval approach that enables market authorization on the basis of less rigorous evidence, in exchange for requiring postmarket evidence generation. An increasing share of therapeutic agents approved by the Food and Drug Administration in recent years are associated with expedited programs. In this article, we provide an overview of the evidentiary standards required by the Food and Drug Administration's expedited development and review programs, summarize the findings of the recent academic literature demonstrating some of the limitations of these programs, and outline potential opportunities to address these limitations. Recent evidence suggests that therapeutic agents in the Food and Drug Administration's expedited programs are approved on the basis of fewer and smaller studies that may lack comparator groups and random allocation, and rather than focusing on clinical outcomes for study endpoints, rely instead on surrogate markers of disease. Once on the market, agents receiving expedited approvals are often quickly incorporated into clinical practice, and evidence generated in the postmarket period may not necessarily address the evidentiary limitations at the time of market entry. Furthermore, not all pathways require additional postmarket studies. Evidence suggests that drugs in expedited approval programs are associated with a greater likelihood that the Food and Drug Administration will take a safety action following market entry. There are several opportunities to improve the timeliness, information value, and validity of the pre- and postmarket studies of therapeutic agents receiving expedited approvals. When use of nonrandomized and uncontrolled studies cannot be avoided prior to market entry, randomized trials should be mandatory in the postmarket period, unless there are strong justifications for not carrying out such studies. In the premarket period, validity of the surrogate markers can be improved by more rigorously evaluating their correlation with patient-relevant clinical outcomes. Opportunities to reduce the duration, complexity, and cost of postmarket randomized trials should not compromise their validity and instead incorporate pragmatic "real-world" design elements. Despite recent enthusiasm for widely using real-world evidence, adaptive designs, and pragmatic trials in the regulatory setting, caution is warranted until large-scale empirical evaluations demonstrate their validity compared to more traditional trial designs.

Study of airborne science experiment management concepts for application to space shuttle. Volume 3: Appendixes

NASA Technical Reports Server (NTRS)

Mulholland, D. R.; Reller, J. O., Jr.; Neel, C. B.; Haughney, L. C.

1973-01-01

Detailed information is presented concerning specific airborne missions in support of the ASSESS program. These missions are the AIDJEX expeditions, meteor shower expeditions, CAT and atmospheric sampling missions, ocean color expeditions, and the Lear Jet missions. For Vol. 2, see N73-31729.

48 CFR 1552.215-72 - Instructions for the Preparation of Proposals.

Code of Federal Regulations, 2013 CFR

2013-10-01

... of the information, to expedite review of the proposal, submit an IBM-compatible software or storage... offeror used another spreadsheet program, indicate the software program used to create this information... submission of a compatible software or device will expedite review, failure to submit a disk will not affect...

48 CFR 1552.215-72 - Instructions for the Preparation of Proposals.

Code of Federal Regulations, 2014 CFR

2014-10-01

... of the information, to expedite review of the proposal, submit an IBM-compatible software or storage... offeror used another spreadsheet program, indicate the software program used to create this information... submission of a compatible software or device will expedite review, failure to submit a disk will not affect...

Characterizing slab inputs in the earliest stages of subduction: Preliminary evidence from fluid-mobile element systematics for IODP Expedition 352 recovered volcanic samples

NASA Astrophysics Data System (ADS)

Sanatan, Keir; Ryan, Jeffrey; Atlas, Zachary; Reagan, Mark

2016-04-01

IODP Expedition 352 recovered ~1.22 km of boninitic and basaltic volcanic rocks from four sites in the Izu-Bonin forearc to examine the volcanic phenomena associated with subduction initiation. While the recovered forearc basalts give little indication for the involvement of slab-derived volatiles, the extensive sequences of boninite series lavas recovered up-section show physical evidence for extensive fluid involvement (heavy vesicularity, explosive eruptive style), along with chemistries indicative of fluid-addition melting of depleted mantle sources. We are attempting to assay the makeup and likely slab provenance of these fluids via their fluid-mobile element (B, As, Cs, Sb, Pb, Li) systematics. Boron abundances measured thus far in fresh boninitic glasses recovered from Holes U1439C and U1442A range from 3-12 ppm, with B/Be and B/La ranging from 7.5-106 and 2-18.5, respectively. While the highest values are comparable to those observed in the most B-enriched Izu-bonin arc rocks, most of the data are at the low end of this range. Cs/Th and Pb/Ce ratios encompass the range of values encountered in IBM boninites in the literature, and are comparable to values for Izu arc lavas, while As/Sm ratios appear to be lower than in arc suites. Li concentrations are elevated relative to basaltic lavas, at 7-17 ppm, and Li/Yb ratios range from 8-22, a factor of four higher than the range encountered in volcanic arc suites. While fluid-mobile element systematics of Izu-Bonin volcanic arc lavas show evidence for inputs of two unique slab components with markedly different fluid-mobile element enrichments, the Izu-Bonin boninites can best be explained as simple mixtures of very depleted mantle and a single slab phase with high abundances of fluid-mobile species, along with elevated K, Ba, and other common subduction indicator species. Volcanic arc lavas globally show evidence for a fluid-mobile element enriched component that appears to be similar to serpentinite. Serpentinites generally show marked enrichments in B, As, and Cs, but lesser enrichments in Pb, Li and other alkaline species (e.g., Savov et al 2005; 2007; Deschamps et al 2011). The pattern of relative fluid-mobile species enrichment in the Exp. 352 boninites differs from that of IBM forearc serpentinites, indicating that either serpentinites are not be the source for the enriching fluids, or if they are that the serpentinites are of shallower or deeper origins than those recovered by ODP drilling, which can result in different elemental enrichment patterns (e.g., Mottl et al 2003; Hattori and Guillot 2007).

Origin of depleted basalts during subduction initiation and early development of the Izu-Bonin-Mariana island arc: Evidence from IODP expedition 351 site U1438, Amami-Sankaku basin

NASA Astrophysics Data System (ADS)

Hickey-Vargas, R.; Yogodzinski, G. M.; Ishizuka, O.; McCarthy, A.; Bizimis, M.; Kusano, Y.; Savov, I. P.; Arculus, R.

2018-05-01

The Izu-Bonin-Mariana (IBM) island arc formed following initiation of subduction of the Pacific plate beneath the Philippine Sea plate at about 52 Ma. Site U1438 of IODP Expedition 351 was drilled to sample the oceanic basement on which the IBM arc was constructed, to better understand magmatism prior to and during the subduction initiation event. Site U1438 igneous basement Unit 1 (150 m) was drilled beneath 1460 m of primarily volcaniclastic sediments and sedimentary rock. Basement basalts are microcrystalline to fine-grained flows and form several distinct subunits (1a-1f), all relatively mafic (MgO = 6.5-13.8%; Mg# = 52-83), with Cr = 71-506 ppm and Ni = 62-342 ppm. All subunits are depleted in non-fluid mobile incompatible trace elements. Ratios such as Sm/Nd (0.35-0.44), Lu/Hf (0.19-0.37), and Zr/Nb (55-106) reach the highest values found in MORB, while La/Yb (0.31-0.92), La/Sm (0.43-0.91) and Nb/La (0.39-0.59) reach the lowest values. Abundances of fluid-mobile incompatible elements, K, Rb, Cs and U, vary with rock physical properties, indicating control by post-eruptive seawater alteration, but lowest abundances are typical of fresh, highly depleted MORBs. Mantle sources for the different subunits define a trend of progressive incompatible element depletion. Inferred pressures of magma segregation are 0.6-2.1 GPa with temperatures of 1280-1470 °C. New 40Ar/39Ar dates for Site U1438 basalts averaging 48.7 Ma (Ishizuka et al., 2018) are younger that the inferred age of IBM subduction initiation based on the oldest ages (52 Ma) of IBM forearc basalts (FAB) from the eastern margin of the Philippine Sea plate. FAB are hypothesized to be the first magma type erupted as the Pacific plate subsided, followed by boninites, and ultimately typical arc magmas over a period of about 10 Ma. Site U1438 basalts and IBM FABs are similar, but Site U1438 basalts have lower V contents, higher Ti/V and little geochemical evidence for involvement of slab-derived fluids. We hypothesize that the asthenospheric upwelling and extension expected during subduction initiation occurred over a broad expanse of the upper plate, even as hydrous fluids were introduced near the plate edge to produce FABs and boninites. Site U1438 basalts formed by decompression melting during the first 3 Ma of subduction initiation, and were stranded behind the early IBM arc as mantle conditions shifted to flux melting beneath a well-defined volcanic front.

Variations of the Indian summer monsoon over the Mio-Pliocene recorded in the Bengal Fan (IODP Exp354): implications for the evolution of the terrestrial biosphere.

NASA Astrophysics Data System (ADS)

Galy, Valier; Feakins, Sarah; Karkabi, Elias; Ponton, Camilo; Galy, Albert; France-Lanord, Christian

2017-04-01

A pressing challenge in climate research is understanding the temporal evolution of the Indian monsoon system; its response to global and regional climatic controls (including warming); as well as implications in terms of vegetation (C4 expansion), erosion of the Himalaya and carbon sequestration in the Bengal Fan. Studies on climate dynamics have recently offered new insights into the mechanistic controls on the monsoon: the tectonic boundary of the Himalaya is implicated as the major control on Indian summer monsoon dynamics today. Since this region has been uplifted since at least the late Oligocene, it is possible to test the response of monsoon precipitation to global and regional climate change, and also understand feedbacks on the climate system via carbon sequestration in the Bengal Fan. The evidence for monsoon intensity changes across the Miocene and Pliocene is currently incomplete given temporal uncertainty and diagenesis in terrestrial records; biases in the records reconstructed from the distal fan; and conflicting evidence from wind speed and aridity metrics for a stronger or weaker monsoon. Our alternative approach is therefore to study the basin-wide hydrological changes recorded in a multi-proxy, multi-site study of the marine sediments of the Bengal Fan recovered during IODP expedition 354. In turbiditic sediments of Himalayan origin, the late Miocene C4 expansion was found in all three long records recovered during expedition 354 (i.e. at sites U1451, U1450 and U1455, from East to West) based on stable carbon isotope composition of terrestrial leaf-wax compounds. Cores from sites U1455 (a reoccupation of DSDP Leg 22 Site 218) provide the highest resolution record of the C4 transition, which appears to occur abruptly within a relatively continuous series of turbiditic sequences. Bio- and magneto-stratigraphic dating of these records by members of Expedition 354 science party is underway and will provide the best stratigraphic constraint of the C4 expansion in the Himalayan system. Hemipelagic sediments generally carry 13C enriched signatures indicative of C4-dominated source areas, and based on a combination of the wind field climatology and the wetness and ecosystems of source regions today, we suggest that these would likely represent wind transport, likely from peninsular India. Interestingly we found hemipelagic horizons carrying this enriched 13C character prior to the C4 expansion recorded in turbiditic sediments, likely revealing an earlier C4 colonization of peninsular India. Based on our preliminary data we thus propose that C4 plants colonized peninsular India around 9-10 Ma. The hydrogen isotopic composition of the same leaf-wax compounds reveals a surprisingly small (on the order of 10 ‰) isotopic shift associated with the late Miocene C4 expansion. In contrast, the hydrogen isotope composition shift observed across the last deglaciation is far greater (ca. 40‰; Hein et al., in prep.). Cores from site U1451, provide a low resolution record across at least the last 26 Myr and appear to indicate a long term hydrological change from ca. 11Ma to ca. 7Ma, as inferred from progressive D enrichment in the biomarker records. These compound specific hydrogen isotope data will be discussed in the context of changing erosion patterns and attendant variations in the strength of the Indian summer monsoon as well as with respect to the mechanisms that led to the C4 expansion.

49 CFR 385.308 - What may cause an expedited action?

Code of Federal Regulations, 2010 CFR

2010-10-01

... SAFETY FITNESS PROCEDURES New Entrant Safety Assurance Program § 385.308 What may cause an expedited... inspections or by any other means, may be subjected to an expedited safety audit or a compliance review or may..., or missing a required endorsement. (2) Operating a vehicle placed out of service for violations of...

Workshop initial report: Expanding the geoscience pipeline by connecting educators with early career IODP scientists

NASA Astrophysics Data System (ADS)

Lewis, J. C.; Cooper, S. K.; Hovan, S. A.; Leckie, R. M.; White, L. D.

2017-12-01

The U.S. is facing challenges in attracting, retaining and diversifying the workforce in the geosciences. A likely contributing factor is the homogeneity of the pool of mentors/role models available both within the workforce and in the U.S. professoriate. Another probable factor is "exposure gaps" among U.S. student populations; i.e., differing access to engaging facets of science, technology, engineering and mathematics (STEM). In response, we organized an 18-day School of Rock workshop onboard the International Ocean Discovery Program (IODP) drilling vessel JOIDES Resolution during a July 2017 transit in the western Pacific. Our objectives were diversity driven, focusing on measures to broaden participation at all levels (i.e., K-12, undergraduate and beyond) in innovative ways (e.g., from place-base curriculum to longitudinal peer mentoring through extracurricular STEM communities). To accomplish this, we designed a recruiting scheme to attract pairs of participants, specifically a teacher from a diverse community and a nearby early-career scientist with an interest in IODP science. By partnering in this way we sought to foster connections that might not naturally emerge, and therein to establish new mechanisms for increased engagement, broader recruitment, enhanced support, and improved retention of students from underrepresented communities in STEM education. We report on initial workshop outcomes that include new curriculum proposals, nascent funding proposals, and innovative connections among secondary educators and early-career scientists. Survey results of our participants gauge the expected impacts of the workshop on perceptions and on plans for future actions aimed at broadening participation.

Expedited Remedial Action Program (SB 923): A California Brownfields initiative

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cambridge, M.; Wolfenden, A.K.

California`s Expedited Remedial Action Program (ERAP) created a comprehensive program that promotes an equitable and expedited approach for redevelopment of properties contaminated with hazardous substances. This bill embodies an emerging trend in environmental policy that permits flexibility, cooperation and creativity without compromising protection to public health or the environment. Within the California Environmental Protection Agency, the Department of Toxic Substances Control (DTSC) is promoting a number of programs to facilitate the restoration of contaminated properties as part of its Brownfields initiative. ERAP represents a potentially more efficient process to remediate sites by minimizing economic risks through a clearly identified liabilitymore » scheme, indemnifying future owners through a covenant not to sue, and providing risk based cleanups that are based on the permanent use of the site.« less

Preliminary Results from Downhole Osmotic Samplers in a Gas Tracer Injection Experiment in the Upper Oceanic Crust on the Eastern Flank of the Juan de Fuca Ridge.

NASA Astrophysics Data System (ADS)

de Jong, M. T.; Clark, J. F.; Neira, N. M.; Fisher, A. T.; Wheat, C. G.

2015-12-01

We present results from a gas tracer injection experiment in the ocean crust on the eastern flank of the Juan de Fuca Ridge, in an area of hydrothermal circulation. Sulfur hexafluoride (SF6) tracer was injected in Hole 1362B in 2010, during IODP Expedition 327. Fluid samples were subsequently collected from a borehole observatory (CORK) installed in this hole and similar CORKs in three additional holes (1026B, 1362A, and 1301A), located 300 to 500 m away. This array of holes is located on 3.5 My old seafloor, as an array oriented subparallel to the Endeavor Segment of Juan de Fuca Ridge. Borehole fluid samples were collected in copper coils using osmotic pumps. In addition to pumps at seafloor wellheads, downhole sampling pumps were installed in the perforated casing in the upper ocean crust. These downhole samplers were intended to produce a high-resolution continuous record of tracer concentrations, including records from the first year after tracer injection in Holes 1362A and 1362B. In contrast, wellhead samplers were not installed on these CORKs holes until 2011, and wellhead records from all CORKs have a record gap of up to one year, because of a delayed expedition in 2012. The downhole samples were recovered with the submersible Alvin in August 2014. SF6 concentrations in downhole samples recovered in 2014 are generally consistent with data obtained from wellhead samples. Of particular interest are the results from Hole 1362B, where a seafloor valve was opened and closed during various recovery expeditions. High resolution tracer curves produced from the 1362B downhole samples confirm that these operations produced an SF6 breakthrough curve corresponding to a classic push-pull test used to evaluate contaminant field locations in terrestrial setting. Complete analyses of downhole samples from these CORKs are expected to produce high-resolution breakthrough curves that will allow more precise analysis and modeling of hydrothermal flow in the study area.

LWD lithostratigraphy, physical properties and correlations across tectonic domains at the NanTroSEIZE drilling transect, Nankai Trough subduction zone, Japan

NASA Astrophysics Data System (ADS)

Tudge, J.; Webb, S. I.; Tobin, H. J.

2013-12-01

Since 2007 the Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) has drilled a total of 15 sites across the Nankai Trough subduction zone, including two sites on the incoming sediments of the Philippine Sea plate (PSP). Logging-while-drilling (LWD) data was acquired at 11 of these sites encompassing the forearc Kumano Basin, upper accretionary prism, toe region and input sites. Each of these tectonic domains is investigated for changes in physical properties and LWD characteristics, and this work fully integrates a large data set acquired over multiple years and IODP expeditions, most recently Expedition 338. Using the available logging-while-drilling data, primarily consisting of gamma ray, resistivity and sonic velocity, a log-based lithostratigraphy is developed at each site and integrated with the core, across the entire NanTroSEIZE transect. In addition to simple LWD characterization, the use of Iterative Non-hierarchical Cluster Analysis (INCA) on the sites with the full suite of LWD data clearly differentiates the unaltered forearc and slope basin sediments from the deformed sediments of the accretionary prism, suggesting the LWD is susceptible to the subtle changes in the physical properties between the tectonic domains. This differentiation is used to guide the development of tectonic-domain specific physical properties relationships. One of the most important physical property relationships between is the p-wave velocity and porosity. To fully characterize the character and properties of each tectonic domain we develop new velocity-porosity relationships for each domain found across the NanTroSEIZE transect. This allows the porosity of each domain to be characterized on the seismic scale and the resulting implications for porosity and pore pressure estimates across the plate interface fault zone.

Biomarker records and paleoenvironment of the central Arctic Ocean during Paleogene times

NASA Astrophysics Data System (ADS)

Weller, P.; Stein, R.

2007-12-01

During IODP Expedition 302 (Arctic Coring Expedition - ACEX), a more than 200 m thick sequence of Paleogene organic-carbon (OC)-rich (black shale-type) sediments has been drilled. Here, we present new biomarker data determined in ACEX sediment samples to decipher processes controlling OC accumulation and their paleo- environmental significance during periods of extreme global warmth and proposed increased freshwater discharge in the early Cenozoic. Specific source-related biomarkers including n-alkanes, fatty acids, isoprenoids, carotenoids, steranes/sterenes, hopanes/hopenes, hopanoic acids, aromatic terpenoids, benzohopanes, long- chain alkenones and organic sulfur compounds show a high variable of compounds, derived from marine, terrestrial and bacterial origin. Based on the biomarker data, the terrestrial OC supply was significantly enriched during the late Paleocene and part of the earliest Eocene, whereas n-alkanes and n-fatty acids in samples from the PETM and Elmo events as well as the middle Eocene indicate increased aquatic contributions. For the latter, an anoxic environment similar to the modern Black Sea, and moderate primary productivity are proposed. The occurrence of C37-alkenenones, which were first determined in the middle part of the Azolla Freshwater Event (about 49 Ma), suggests that significant amounts of the OC is of marine origin during in middle Eocene. During the Eocene, a prominant cooling and onset of first significant IRD deposition near 45.4 Ma were recorded in the terrigenous coarse fraction of the ACEX sequence, related to iceberg and/or sea-ice transport (K. St. John, Paleoceanography, in press). This cooling trend is also reflected in the alkenone SST, showing a temperature decrease of about 10°C between about 49 and 44 Ma.

Reconstructing Holocene temperature and salinity variations in the western Baltic Sea region: a multi-proxy comparison from the Little Belt (IODP Expedition 347, Site M0059)

NASA Astrophysics Data System (ADS)

Kotthoff, Ulrich; Groeneveld, Jeroen; Ash, Jeanine L.; Fanget, Anne-Sophie; Quintana Krupinski, Nadine; Peyron, Odile; Stepanova, Anna; Warnock, Jonathan; Van Helmond, Niels A. G. M.; Passey, Benjamin H.; Rønø Clausen, Ole; Bennike, Ole; Andrén, Elinor; Granoszewski, Wojciech; Andrén, Thomas; Filipsson, Helena L.; Seidenkrantz, Marit-Solveig; Slomp, Caroline P.; Bauersachs, Thorsten

2017-12-01

Sediment records recovered from the Baltic Sea during Integrated Ocean Drilling Program Expedition 347 provide a unique opportunity to study paleoenvironmental and climate change in central and northern Europe. Such studies contribute to a better understanding of how environmental parameters change in continental shelf seas and enclosed basins. Here we present a multi-proxy-based reconstruction of paleotemperature (both marine and terrestrial), paleosalinity, and paleoecosystem changes from the Little Belt (Site M0059) over the past ˜ 8000 years and evaluate the applicability of inorganic- and organic-based proxies in this particular setting. All salinity proxies (diatoms, aquatic palynomorphs, ostracods, diol index) show that lacustrine conditions occurred in the Little Belt until ˜ 7400 cal yr BP. A connection to the Kattegat at this time can thus be excluded, but a direct connection to the Baltic Proper may have existed. The transition to the brackish-marine conditions of the Littorina Sea stage (more saline and warmer) occurred within ˜ 200 years when the connection to the Kattegat became established after ˜ 7400 cal yr BP. The different salinity proxies used here generally show similar trends in relative changes in salinity, but often do not allow quantitative estimates of salinity. The reconstruction of water temperatures is associated with particularly large uncertainties and variations in absolute values by up to 8 °C for bottom waters and up to 16 °C for surface waters. Concerning the reconstruction of temperature using foraminiferal Mg  /  Ca ratios, contamination by authigenic coatings in the deeper intervals may have led to an overestimation of temperatures. Differences in results based on the lipid paleothermometers (long chain diol index and TEXL86) can partly be explained by the application of modern-day proxy calibrations to intervals that experienced significant changes in depositional settings: in the case of our study, the change from freshwater to marine conditions. Our study shows that particular caution has to be taken when applying and interpreting proxies in coastal environments and marginal seas, where water mass conditions can experience more rapid and larger changes than in open ocean settings. Approaches using a multitude of independent proxies may thus allow a more robust paleoenvironmental assessment.

Active Marine Subsurface Bacterial Population Composition in Low Organic Carbon Environments from IODP Expedition 320

NASA Astrophysics Data System (ADS)

Shepard, A.; Reese, B. K.; Mills, H. J.; IODP Expedition 320 Shipboard Science Party

2011-12-01

The marine subsurface environment contains abundant and active microorganisms. These microbial populations are considered integral players in the marine subsurface biogeochemical system with significance in global geochemical cycles and reservoirs. However, variations in microbial community structure, activity and function associated with the wide-ranging sedimentary and geochemical environments found globally have not been fully resolved. Integrated Ocean Drilling Program Expedition 320 recovered sediments from site U1332. Two sampling depths were selected for analysis that spanned differing lithological units in the sediment core. Sediments were composed of mostly clay with zeolite minerals at 8 meters below sea floor (mbsf). At 27 mbsf, sediments were composed of alternating clayey radiolarian ooze and nannofossil ooze. The concentration of SO42- had little variability throughout the core and the concentration of Fe2+ remained close to, or below, detection limits (0.4 μM). Total organic carbon content ranged from a low of 0.03 wt% to a high of 0.07 wt% between 6 and 30 mbsf providing an opportunity to evaluate marine subsurface microbial communities under extreme electron donor limiting conditions. The metabolically active fraction of the bacterial population was isolated by the extraction and amplification of 16S ribosomal RNA. Pyrosequencing of 16S rRNA transcripts and subsequent bioinformatic analyses provided a robust data set (15,931 total classified sequences) to characterize the community at a high resolution. As observed in other subsurface environments, the overall diversity of active bacterial populations decreased with depth. The population shifted from a diverse but evenly distributed community at approximately 8 mbsf to a Firmicutes dominated population at 27 mbsf (80% of sequences). A total of 95% of the sequences at 27 mbsf were grouped into three genera: Lactobacillus (phylum Firmicutes) at 80% of the total sequences, Marinobacter (phylum Proteobacteria) at 8%, and Formosa (phylum Bacteroidetes) at 7%. These lineages support a paradigm suggesting the importance of fermentation in the subsurface. However, this study extends the predicted range for fermentation below the shallow subsurface and into organic carbon limited marine sediments. Other previously characterized subsurface active populations from environments with higher organic carbon concentrations do not show similar levels of reduced diversity or predominance of fermentative populations. This study further emphasizes the spatial variability of microbial populations in the deep subsurface and highlights the need for continued exploration.

Transient Deformation Patterns in Response to Quaternary Glacial Advance-Retreat Across the Offshore St. Elias Mountains, southern Alaska

NASA Astrophysics Data System (ADS)

Worthington, L. L.; Clary, W. A.; Daigle, H.; Koons, P. O.; Gulick, S. P. S.; Jaeger, J. M.

2016-12-01

The southern Alaska margin, home to the St. Elias Mountains, the highest coastal mountain range on Earth experiencing the highest erosion rates on Earth, provides a superb setting for evaluating competing influences of rheological and climate control on orogen development. Previous studies have recognized this potential, but conclusions were limited due to the absence of information on the time-dependent behavior of climate and rheological processes. These limitations can now be surpassed due to 1) the recent availability of high-precision age constraints on the structural and stratigraphic evolution of offshore sediments and structures and 2) geotechnical information on the extent of dewatering and related spatial changes in the material properties of these sediments. We correlate emerging results from Integrated Ocean Drilling Program (IODP) Expedition 341 Sites U1420 and U1421 with regional seismic data across the continental shelf and slope to determine the spatial and temporal evolution of thrusting in response to Yakutat-North American convergence. Our mapping shows that the pattern of faulting changed from distributed across the shelf to highly localized away from the primary glacial depocenter over the course of one glacial cycle. Core samples suggest that the glacially derived sediment is overpressured, with pore pressures possibly reaching >90% of lithostatic stress. Elevated pore pressures develop rapidly in response to focused glaciomarine sedimentation, in addition to direct ice loading, and may induce a transient state of wedge reorganization manifested as a change in localization of deformation. This relationship suggests that the additive response of pore pressure variations over glacial cycles throughout the Pleistocene and Holocene result in constant reorganization of deformation style and location.

Investigating the Differences in the Total and Active Microbial Community of Mid-Atlantic Ridge Sediments

NASA Astrophysics Data System (ADS)

Sobol, M. S.; Zinke, L. A.; Orcutt, B.; Mills, H. J.; Edwards, K. J.; Girguis, P. R.; Reese, B. K.

2016-02-01

Microbes in the marine deep subsurface are key mediators of many geochemical cycles. It is important to understand how microbial communities and the diversity of those communities impacts geochemical cycling. Sediment cores were collected from IODP (Integrated Ocean Drilling Program) Expedition 336 to the western flank of the mid-Atlantic ridge also referred to as North Pond. The dissolved oxygen concentration decreased with depth for 60-70 mbsf, followed by a sharp increase in oxygen until it terminated at the basement. The 16S rRNA genes (DNA) and transcripts (RNA) were extracted simultaneously using a method designed by Reese et al. (2013) to differentiate between the total and active microbial community structures, respectively, as well as correlate the putative metabolism with the geochemistry. We observed many differences between the active and total communities. Sequences most closely related to Cyanobacteria were found to dominate the total community at both sites, but were found in small numbers in the active community. The most abundant phyla in the active community were Alphaproteobacteria, which suggests that they may have high activity even though the abundance was not as great in the total community. This suggests that, even in small numbers, bacteria are capable of contributing greatly to their environment. Principal Component Analysis (PCA) and Singular Value Decomposition (SVD) showed that iron-reducing bacteria in the active (RNA) community correlated strongly with solid phase iron oxides. SVD also showed that the putative nitrate reducers in the active community were found in greater abundance where porewater NO3- and NO2- total concentrations were elevated. Overall, the active (RNA) community correlated significantly with the geochemistry whereas the total (DNA) community did not. Therefore, RNA analysis yields a more accurate representation of how microbial communities impact geochemical cycling.

δ15Nbulk oscillations linked to monsoon-induced denitrification during the past 1 m.y. in the Eastern Arabian Sea (IODP Exp. 355 Site U1456)

NASA Astrophysics Data System (ADS)

Khim, B. K.; Kim, J. E.; Lee, J.; Ikehara, M.; Clift, P. D.; Pandey, D.; Kulhanek, D. K.; Science Party, E.

2016-12-01

The Arabian Sea is characterized by a large pool of denitrifying water at intermediate water depths, which plays an important role in the marine nitrogen cycle and resultant response to climate change. A growing body of research emphasizes strong linkage between denitrification strength in the Arabian Sea and climate change at both orbital and millennial timescales. Drilling by International Ocean Discovery Program Expedition 355 was conducted at Site U1456 in the Laxmi Basin, Eastern Arabian Sea, 475 km from the Indian coastline and 820 km south of the modern Indus River Delta. Four lithologic units are defined onboard at the Site U1456. A total of 282 samples were collected from a composite section of Unit I consisting of Holes U1456A and U1456C. Unit I is composed mostly of nannofossil ooze and/or foraminifer-rich nannofossil ooze with interbedded clay, silt, and sand layers. Oxygen isotope measurements of planktonic foraminifera (G. ruber and G. sacculifer), together with shipboard biostratigraphic and paleomagnetic data, constrain the age of Unit I to younger than about 1.2 Ma. The δ15Nbulk values fluctuate from 4.5‰ to 9.6‰ with a mean of 7.3(±0.95)‰. Higher δ15Nbulk values coincide with interglacial intervals whereas lower δ15Nbulk values correspond to glacial intervals, representing clear glacial-interglacial cyclicity. These variations demonstrate the distinct climatic linkage with the degree of denitrification at orbital timescales, in association with changes in hydrography and productivity. The relation between denitrification and monsoon intensity, previously reported for the continental margins of the Arabian Sea, is also recorded in the deep water sediments.

Climate changes in south western Iberia and Mediterranean Outflow variations during two contrasting cycles of the last 1 Myrs: MIS 31-MIS 30 and MIS 12-MIS 11

NASA Astrophysics Data System (ADS)

Sánchez Goñi, M. F.; Llave, E.; Oliveira, D.; Naughton, F.; Desprat, S.; Ducassou, E.; Hodell, D. A.; Hernández-Molina, F. J.

2016-01-01

Grain size analysis and physical properties of Sites U1388, U1389 and U1390 collected in the Contourite Depositional System of the Gulf of Cádiz during the Integrated Ocean Drilling Program (IODP) Expedition 339 "Mediterranean Outflow" reveal relative changes in bottom current strength, a tracer of the dynamics of the Mediterranean Outflow Water (MOW), before and after the Middle Pleistocene Transition (MPT). The comparison of MOW behavior with climate changes identified by the pollen analysis and δ18O benthic foraminifera measurements of Site U1385, the Shackleton Site, collected in the south western Iberian margin shows that the interval MIS 31-MIS 30, ~ 1.1-1.05 million years ago (Ma), before the MPT, was marked by wetter climate and weaker bottom current than the interval MIS 12-MIS 11 (0.47-0.39 Ma), after the MPT. Similarly, the increase in fine particles from these glacials to interglacials and in coarse fraction from interglacials to glacials was coeval with forest and semi-desert expansions, respectively, indicating the lowering/enhancement of MOW strength during periods of regional increase/decrease of moisture. While these findings may not necessarily apply to all glacial/interglacial cycles, they nonetheless serve as excellent supporting examples of the hypothesis that aridification can serve as a good tracer for MOW intensity. The strongest regional aridity during MIS 12 coincides with a remarkable increase of coarse grain size deposition and distribution that we interpret as a maximum in MOW strength. This MOW intensification may have pre-conditioned the North Atlantic by increasing salinity, thereby triggering the strong resumption of the Meridional Overturning Circulation that could contribute to the great warmth that characterizes the MIS 11c super-interglacial.

The Eocene Arctic Azolla bloom: environmental conditions, productivity and carbon drawdown.

PubMed

Speelman, E N; Van Kempen, M M L; Barke, J; Brinkhuis, H; Reichart, G J; Smolders, A J P; Roelofs, J G M; Sangiorgi, F; de Leeuw, J W; Lotter, A F; Sinninghe Damsté, J S

2009-03-01

Enormous quantities of the free-floating freshwater fern Azolla grew and reproduced in situ in the Arctic Ocean during the middle Eocene, as was demonstrated by microscopic analysis of microlaminated sediments recovered from the Lomonosov Ridge during Integrated Ocean Drilling Program (IODP) Expedition 302. The timing of the Azolla phase (approximately 48.5 Ma) coincides with the earliest signs of onset of the transition from a greenhouse towards the modern icehouse Earth. The sustained growth of Azolla, currently ranking among the fastest growing plants on Earth, in a major anoxic oceanic basin may have contributed to decreasing atmospheric pCO2 levels via burial of Azolla-derived organic matter. The consequences of these enormous Azolla blooms for regional and global nutrient and carbon cycles are still largely unknown. Cultivation experiments have been set up to investigate the influence of elevated pCO2 on Azolla growth, showing a marked increase in Azolla productivity under elevated (760 and 1910 ppm) pCO2 conditions. The combined results of organic carbon, sulphur, nitrogen content and 15N and 13C measurements of sediments from the Azolla interval illustrate the potential contribution of nitrogen fixation in a euxinic stratified Eocene Arctic. Flux calculations were used to quantitatively reconstruct the potential storage of carbon (0.9-3.5 10(18) gC) in the Arctic during the Azolla interval. It is estimated that storing 0.9 10(18) to 3.5 10(18) g carbon would result in a 55 to 470 ppm drawdown of pCO2 under Eocene conditions, indicating that the Arctic Azolla blooms may have had a significant effect on global atmospheric pCO2 levels through enhanced burial of organic matter.

Biomarker Constraints on Arctic Surface Water Conditions During the Middle Eocene

NASA Astrophysics Data System (ADS)

Speelman, E. N.; Reichart, G.; Brinkhuis, H.; Sinninghe Damste, J. S.; de Leeuw, J. M.; van Kempen, M.

2007-12-01

Through analyses of unique microlaminated sediments of Arctic drill cores, recovered from the Lomonosov Ridge in the central Arctic Ocean during Integrated Ocean Drilling Program (IODP) Expedition 302, it has been shown that enormous quantities of the free floating freshwater fern \\textit {Azolla} grew and reproduced in situ in the Arctic Ocean during the middle Eocene (Brinkhuis et al., Nature, 2006).The presence of the freshwater fern Azolla, both within the Arctic Basin and in all Nordic seas, suggests that at least the sea surface waters were frequently dominated by fresh- to brackish water during an interval of at least 800 kyr. However, to which degree the Arctic Basin became fresh and what the consequences of these enormous Azolla blooms were for regional and global nutrient cycles is still largely unknown. Comparing samples of extant Azolla, including its nitrogen fixing symbionts, with samples from the Arctic Azolla interval revealed the presence of a group of highly specific biomarkers. These biomarkers are closely related to similar organic compounds that have been suggested to play a crucial role in the biogeochemistry of nitrogen fixing bacteria. This finding, therefore, potentially implies that this symbioses dates back to at least the middle Eocene. Furthermore, this particular symbiosis was probably crucial in triggering basin wide Azolla blooms. We now aim to measure compound specific stable hydrogen isotope values of these biomarkers which should provide insight into the degree of mixing between high salinity (isotopically heavy) deeper and low salinity surface water (isotopically light). The results of these compound specific isotope analyses will be extrapolated using calibrations from controlled growth experiments and subsequently evaluated using climate modeling experiments.

Late Pliocene-Early Pleistocene oscillations in Mediterranean Overflow water: a new perspective from the Iberian Margin

NASA Astrophysics Data System (ADS)

Alonso-Garcia, M.; Salgueiro, E.; Rodrigues, T.; Alvarez Zarikian, C. A.; Kuhnert, H.; Roehl, U.; Voelker, A. H. L.; Sierro, F. J.; Abrantes, F. F. G.

2016-12-01

During the Late Pliocene to the Early Pleistocene the Earth experienced a transition from the warm Pliocene climate, with high greenhouse gases concentrations, to a colder climate with significant expansion of ice-sheets in the Northern Hemisphere and alternation between glacial and interglacial periods. Several hypotheses have been put forward to explain this climate transition, and recently, the enhancement of the Mediterranean Overflow Water (MOW) was suggested to have played a major role since it contributes high salinity water to the North Atlantic. Sedimentary records from the last glacial cycle and modelling experiments evidenced this link and suggested that the MOW injection of salty water to intermediate depths may have enhanced the upper branch of NADW, which ultimately reinvigorated the whole Atlantic Meridional overturning circulation. Here we present sedimentological and paleontological data from Site U1391 (37° N; 9° W; 1085 m water depth), recovered on the Southwest Iberian Margin during the Integrated Ocean Drilling Program (IODP) Expedition 339. This site is located in a plastered drift in the path of the MOW and offers high sedimentation rates to perform high resolution studies of past climatic and oceanographic conditions. In this study, we combined XRF geochemical data (from X-ray fluorescence core scanning) with grain-size, benthic foraminifer δ18O and δ13C, and ostracod records to reconstruct deep water circulation and climatic conditions during the Plio-Pleistocene transition. The high-resolution record of the XRF analysis indicates a switch in the response of MOW to climate changes across this transition. Early Pleistocene glacial-interglacial cycles show a stronger coupling between MOW oscillations (as indicated by the Zr/Al ratio) and sea surface temperature conditions (as indicated by the Ca/Ti ratio).

Distribution of anaerobic carbon monoxide dehydrogenase genes in deep subseafloor sediments.

PubMed

Hoshino, T; Inagaki, F

2017-05-01

Carbon monoxide (CO) is the simplest oxocarbon generated by the decomposition of organic compounds, and it is expected to be in marine sediments in substantial amounts. However, the availability of CO in the deep subseafloor sedimentary biosphere is largely unknown even though anaerobic oxidation of CO is a thermodynamically favourable reaction that possibly occurs with sulphate reduction, methanogenesis, acetogenesis and hydrogenesis. In this study, we surveyed for the first time the distribution of the CO dehydrogenase gene (cooS), which encodes the catalytic beta subunit of anaerobic CO dehydrogenase (CODH), in subseafloor sediment-core samples from the eastern flank of the Juan de Fuca Ridge, Mars-Ursa Basin, Kumano Basin, and off the Shimokita Peninsula, Japan, during Integrated Ocean Drilling Program (IODP) Expeditions 301, 308 and 315 and the D/V Chikyu shakedown cruise CK06-06, respectively. Our results show the occurrence of diverse cooS genes from the seafloor down to about 390 m below the seafloor, suggesting that microbial communities have metabolic functions to utilize CO in anoxic microbial ecosystems beneath the ocean floor, and that the microbial community potentially responsible for anaerobic CO oxidation differs in accordance with possible energy-yielding metabolic reactions in the deep subseafloor sedimentary biosphere. Little is known about the microbial community associated with carbon monoxide (CO) in the deep subseafloor. This study is the first survey of a functional gene encoding anaerobic carbon monoxide dehydrogenase (CODH). The widespread occurrence of previously undiscovered CO dehydrogenase genes (cooS) suggests that diverse micro-organisms are capable of anaerobic oxidation of CO in the deep subseafloor sedimentary biosphere. © 2017 The Society for Applied Microbiology.

Anatexis at the roof of an oceanic magma chamber at IODP Site 1256 (equatorial Pacific): an experimental study

NASA Astrophysics Data System (ADS)

Erdmann, Martin; Fischer, Lennart A.; France, Lydéric; Zhang, Chao; Godard, Marguerite; Koepke, Jürgen

2015-04-01

Replenished axial melt lenses at fast-spreading mid-oceanic ridges may move upward and intrude into the overlying hydrothermally altered sheeted dikes, resulting in high-grade contact metamorphism with the potential to trigger anatexis in the roof rocks. Assumed products of this process are anatectic melts of felsic composition and granoblastic, two-pyroxene hornfels, representing the residue after partial melting. Integrated Ocean Drilling Program Expeditions 309, 312, and 335 at Site 1256 (eastern equatorial Pacific) sampled such a fossilized oceanic magma chamber. In this study, we simulated magma chamber roof rock anatectic processes by performing partial melting experiments using six different protoliths from the Site 1256 sheeted dike complex, spanning a lithological range from poorly to strongly altered basalts to partially or fully recrystallized granoblastic hornfels. Results show that extensively altered starting material lacking primary magmatic minerals cannot reproduce the chemistry of natural felsic rocks recovered in ridge environments, especially elements sensitive to hydrothermal alteration (e.g., K, Cl). Natural geochemical trends are reproduced through partial melting of moderately altered basalts from the lower sheeted dikes. Two-pyroxene hornfels, the assumed residue, were reproduced only at low melting degrees (<20 vol%). The overall amphibole absence in the experiments confirms the natural observation that amphibole is not produced during peak metamorphism. Comparing experimental products with the natural equivalents reveals that water activity ( aH2O) was significantly reduced during anatectic processes, mainly based on lower melt aluminum oxide and lower plagioclase anorthite content at lower aH2O. High silica melt at the expected temperature (1000-1050 °C; peak thermal overprint of two-pyroxene hornfels) could only be reproduced in the experimental series performed at aH2O = 0.1.

A Descriptive and Interpretative Information System for the IODP

NASA Astrophysics Data System (ADS)

Blum, P.; Foster, P. A.; Mateo, Z.

2006-12-01

The ODP/IODP has a long and rich history of collecting descriptive and interpretative information (DESCINFO) from rock and sediment cores from the world's oceans. Unlike instrumental data, DESCINFO generated by subject experts is biased by the scientific and cultural background of the observers and their choices of classification schemes. As a result, global searches of DESCINFO and its integration with other data are problematical. To address this issue, the IODP-USIO is in the process of designing and implementing a DESCINFO system for IODP Phase 2 (2007-2013) that meets the user expectations expressed over the past decade. The requirements include support of (1) detailed, material property-based descriptions as well as classification-based descriptions; (2) global searches by physical sample and digital data sources as well as any of the descriptive parameters; (3) user-friendly data capture tools for a variety of workflows; and (4) extensive visualization of DESCINFO data along with instrumental data and images; and (5) portability/interoperability such that the system can work with database schemas of other organizations - a specific challenge given the schema and semantic heterogeneity not only among the three IODP operators but within the geosciences in general. The DESCINFO approach is based on the definition of a set of generic observable parameters that are populated with numeric or text values. Text values are derived from controlled, extensible hierarchical value lists that allow descriptions at the appropriate level of detail and ensure successful data searches. Material descriptions can be completed independently of domain-specific classifications, genetic concepts, and interpretative frameworks.

Utilizing the International GeoSample Number Concept during ICDP Expedition COSC

NASA Astrophysics Data System (ADS)

Conze, Ronald; Lorenz, Henning; Ulbricht, Damian; Gorgas, Thomas; Elger, Kirsten

2016-04-01

The concept of the International GeoSample Number (IGSN) was introduced to uniquely identify and register geo-related sample material, and make it retrievable via electronic media (e.g., SESAR - http://www.geosamples.org/igsnabout). The general aim of the IGSN concept is to improve accessing stored sample material worldwide, enable the exact identification, its origin and provenance, and also the exact and complete citation of acquired samples throughout the literature. The ICDP expedition COSC (Collisional Orogeny in the Scandinavian Caledonides, http://cosc.icdp-online.org) prompted for the first time in ICDP's history to assign and register IGSNs during an ongoing drilling campaign. ICDP drilling expeditions are using commonly the Drilling Information System DIS (http://doi.org/10.2204/iodp.sd.4.07.2007) for the inventory of recovered sample material. During COSC IGSNs were assigned to every drill hole, core run, core section, and sample taken from core material. The original IGSN specification has been extended to achieve the required uniqueness of IGSNs with our offline-procedure. The ICDP name space indicator and the Expedition ID (5054) are forming an extended prefix (ICDP5054). For every type of sample material, an encoded sequence of characters follows. This sequence is derived from the DIS naming convention which is unique from the beginning. Thereby every ICDP expedition has an unlimited name space for IGSN assignments. This direct derivation of IGSNs from the DIS database context ensures the distinct parent-child hierarchy of the IGSNs among each other. In the case of COSC this method of inventory-keeping of all drill cores was done routinely using the ExpeditionDIS during field work and subsequent sampling party. After completing the field campaign, all sample material was transferred to the "Nationales Bohrkernlager" in Berlin-Spandau, Germany. Corresponding data was subsequently imported into the CurationDIS used at the aforementioned core storage facility. This CurationDIS assigns IGSNs on samples newly taken in the repository in the identical fashion as done in the field. Thereby, the parent-child linkage of the IGSNs is ensured consistently throughout the entire sampling process. The only difference between ExpeditionDIS and CurationDIS sample curation is using the name space ICDP and BGRB respectively as part of the corresponding ID string. To prepare the IGSN registry, a set of metadata is generated for every assigned IGSN using the DIS, which is then exported from the DIS into one common xml-file. The xml-file is based on the SESAR schema and a proposal of IGSN e.V. (http://schema.igsn.org). This systematics has been recently extended for drilling data to achieve additional information for future retrieval options. The two allocation agents GFZ Potsdam und PANGAEA are currently involved in the registry of IGSNs in the case of COSC drill campaigns. An example for the IGSN registration of the COSC-1 drill hole A (5054_1_A) is "ICDP5054EEW1001" and can be resolved using the URL http://hdl.handle.net/10273/ICDP5054EEW1001. Opening the landing page for the complete COSC core material for this particular hole showcases graphically a hierarchical tree entitled "Sample Family". An example of an IGSN citation associated with a COSC sample set is featured on an EGU-2016 poster presentation by Ulrich Harms, Johannes Hierold et al. (EGU2016-8646).

ISS Expedition 43 Soyuz Rollout

NASA Image and Video Library

2015-04-06

NASA TV (NTV) video file of ISS Expedition 43 Soyuz rollout to launch pad. Includes footage of the rollout by train; Rocket hoisted into upright position; interview with Bob Behnken, Chief of Astronaut Office; Dr. John Charles, chief of the International Science Office of NASA's Human Research Program , Johnson Space Center; and family and friends speaking with and saying goodbye to ISS Expedition 43 - 46 One Year crewmember Scott Kelly .

Acoustic and mechanical properties of Nankai accretionary prism core samples

NASA Astrophysics Data System (ADS)

Raimbourg, Hugues; Hamano, Yozo; Saito, Saneatsu; Kinoshita, Masataka; Kopf, Achim

2011-04-01

We studied undeformed sediment and accreted strata recently recovered by Ocean Drilling Program/Integrated Ocean Drilling Program (ODP/IODP) drilling in Nankai Trough convergent margin to unravel the changes in physical properties from initial deposition to incipient deformation. We have derived acoustic (Vp) and mechanical (uniaxial poroelastic compliance, compaction amplitude) properties of samples from various drill sites along the Muroto (ODP 1173) and Kii transects (IODP C0001, C0002, C0006, and C0007) from isotropic loading tests where confining and pore pressure were independently applied. We quantified the dependence of Vp on both effective (Peff) and confining (Pc) pressure, which can be used to correct atmospheric pressure measurements of Vp. Experimental Vp obtained on core samples extrapolated to in situ conditions are slightly higher than logging-derived velocities, which can be attributed either to velocity dispersion or to the effect of large-scale faults and weak zones on waves with longer wavelength. In the high-porosity (30%-60%) tested sediments, velocities are controlled at first order by porosity and not by lithology, which is in agreement with our static measurements of drained framework incompressibility, much smaller than fluid incompressibility. Rather than framework incompressibility, shear modulus is probably the second-order control on Vp, accounting for most of the difference between actual Vp and the prediction by Wood's (1941) suspension model. We also quantified the mechanical state of Nankai samples in terms of anisotropy, diagenesis, and consolidation. Both acoustic and mechanical parameters reveal similar values in vertical and horizontal directions, attesting to the very low anisotropy of the tested material. When considering the porous samples of the Upper Shikoku Basin sediments (Site 1173) as examples of diagenetically cemented material, several mechanical and acoustic attributes appeared as reliable experimental indicators of the presence of intergrain cementation. We also detected incipient cementation in samples from IODP Site C0001 (accretionary prism unit). In terms of consolidation, we distinguished two classes of material response (shallow, deformable samples and deep, hardly deformable ones) based on the amount of compaction upon application of a Peff large with respect to the inferred in situ value, with a transition that might be related to a critical porosity.

A deep oxic ecosystem in the subseafloor South Pacific Gyre

NASA Astrophysics Data System (ADS)

D'Hondt, S. L.; Inagaki, F.; Alvarez Zarikian, C. A.; Integrated Ocean Drilling Program Expedition 329 Shipboard Scientific Party

2011-12-01

Scientific ocean drilling has demonstrated the occurrence of rich microbial communities, abundant active cells and diverse anaerobic activities in anoxic subseafloor sediment. Buried organic matter from the surface photosynthetic world sustains anaerobic heterotrophs in anoxic sediment as deeply buried as 1.6 km below the seafloor. However, these studies have been mostly restricted to the organic-rich sediment of continental margins and biologically productive regions. IODP Expedition 329 discovered that subseafloor habitat and life are fundamentally different in the vast expanse of organic-poor sediment that underlies Earth's largest oceanic province, the South Pacific Gyre (SPG). Dissolved O2 and dissolved major nutrients (C, N, P) are present throughout the entire sediment sequence and the upper basaltic basement of the SPG. The drilled sediment is up to 75 m thick. Although heterotrophic O2 reduction (aerobic respiration) persists for millions of years in SPG sediment (which accumulates very slowly), it falls below minimum detection just a few meters to tens of meters beneath the SPG seafloor. Cell concentrations approach minimum detection at similar depths, but are intermittently detectable throughout the entire sediment sequence. In situ radiolysis of water may be a significant source of energy for the microbes that inhabit the deepest (oldest) sediment.

Okeanos Explorer 2014 Gulf of Mexico Expedition: engaging and connecting with diverse and geographically dispersed audiences

NASA Astrophysics Data System (ADS)

Russell, C. W.; Elliott, K.; Lobecker, E.; McKenna, L.; Haynes, S.; Crum, E.; Gorell, F.

2014-12-01

From February to May 2014, NOAA Ship Okeanos Explorer conducted a telepresence-enabled ocean exploration expedition addressing NOAA and National deepwater priorities in the U.S. Gulf of Mexico. The community-driven expedition connected diverse and geographically dispersed audiences including scientists from industry, academia, and government, and educators, students, and the general public. Expedition planning included input from the ocean science and management community, and was executed with more than 70 scientists and students from 14 U.S. states participating from shore in real time. Training the next generation permeated operations: a mapping internship program trained undergraduate and graduate students; an ROV mentorship program trained young engineers to design, build and operate the system; and undergraduate through doctoral students around the country collaborated with expedition scientists via telepresence. Online coverage of the expedition included background materials, daily updates, and mission logs that received more than 100,000 visits by the public. Live video feeds of operations received more than 700,000 views online. Additionally, professional development workshops hosted in multiple locations throughout the spring introduced educators to the Okeanos Explorer Educational Materials Collection and the live expedition, and taught them how to use the website and education resources in their classrooms. Social media furthered the reach of the expedition to new audiences, garnered thousands of new followers and provided another medium for real-time interactions with the general public. Outreach continued through live interactions with museums and aquariums, Exploration Command Center tours, outreach conducted by partners, and media coverage in more than 190 outlets in the U.S. and Europe. Ship tours were conducted when the ship came in to port to engage local scientists, ocean managers, and educators. After the expedition, data and products were archived and quickly shared with ocean managers and scientists working in the region, providing a baseline of publicly available data and stimulating follow-on exploration, research and management activities within a few months of expedition completion.

Seismic anisotropy from walk-around VSP data in the Kumano basin south of Kii Peninsula (IODP Site C0009A)

NASA Astrophysics Data System (ADS)

Tsuji, T.; Hino, R.; Sanada, Y.; Park, J.; No, T.; Araki, E.; Kinoshita, M.; Bangs, N. L.; von Huene, R.; Moore, G. F.

2010-12-01

We estimated seismic anisotropy from the walk-around Vertical Seismic Profiling (VSP) data in Site C0009A obtained during Integrated Ocean Drilling Program (IODP) Expedition 319. It is generally agreed that seismic anisotropy within sediments is related to the cracks. For vertical cracks (Horizontal Transverse Isotropy; HTI), the fast velocity direction coincides with the direction of crack alignment, while the degree of velocity difference provides information about crack density (Crampin, 1985). If cracks are produced by a regional tectonic stress field, seismic anisotropy can be used to estimate stress orientation and magnitude. In unconsolidated sequence, furthermore, the stress-induced anisotropy can be observed due to increasing contact between grains (Johnson et al., 1998). In this case (increasing grain-contact), the fast velocity direction from walk-around VSP experiment is also consistent with the principal horizontal stress direction. Site C0009A is located in the Kumano basin where ~1350m unconsolidated Kumano basin sediment overlies the accretionary prism. During VSP operations, we obtained walk-away, walk-around, and zero-offset VSP data (Saffer et al., 2009). We used mainly walk-around VSP data to study seismic anisotropy. In the walk-around VSP experiments, R/V Kairei deployed 4 air-gun strings (128 L total volume) and generated 275 shots. The shooting interval was 30s and the distance from the borehole was a constant 3.5 km. We deployed the Vertical Seismic Imager (VSI) wireline tool into the borehole between 2989 and 3218m below the sea surface (935-1164m below seafloor). This interval corresponds to the bottom of the Kumano basin sediment section. From the walk-around VSP data, we obtained the following anisotropic parameters: (1) P-wave velocity anisotropy derived from azimuthal velocity analysis (Grechka and Tsvankin, 1998), (2) P-wave amplitude variation with azimuth (AVAZ), and (3) S-wave amplitude variation with azimuth associated with S-wave splitting (Haacke et al., 2009). We observed the S-wave splitting both from the upgoing and downgoing converted S-waves. These analyses demonstrate that the P-wave velocity anisotropy within the Kumano basin sediment (above the VSI tool) is ~5 %. The fast velocity direction and strong amplitude direction are aligned with the convergence vector of the Philippine Sea plate. The fast velocity as well as strong amplitude is clearly observed for at 180 degree from the convergence vector. Therefore the dip of the Kumano basin sequence (Tilted Transverse Isotropy; TTI) should have only a subtle effect on our results. These results indicate that the maximum horizontal stress orientation is the subduction direction at Site C0009C. This observation is consistent with the principal stress orientation estimated from borehole breakout at same borehole (Kinoshita et al., 2008).

Structure and fault mechanics of the shallow rupture zone of the 2011 Tohoku-oki earthquake, IODP expedition 343/343T (Invited)

NASA Astrophysics Data System (ADS)

Chester, F. M.

2013-12-01

The Japan Trench convergent margin produces frequent large interplate earthquakes greater than M7.5, and is known to display the primary characteristics of non-accretionary margins. The 2011 Mw 9.0 Tohoku-oki earthquake demonstrates the capability of this margin to rupture the full extent of the seismogenic zone and up-dip to the trench axis in a single great event. A variety of observations indicate that the slip magnitude of this rupture increased towards the trench, with 50+ m of slip occurring at the ~20-km-wide frontal prism of accreted sediments and lower trench slope. IODP expedition 343/343T (JFAST) was designed to address fundamental questions of earthquake physics through rapid-response drilling, but also provides new information on sediment accretion and the architecture of the frontal prism. The JFAST drill site is located above a horst block in the subducting plate and 6 km landward from the trench axis; three boreholes were drilled through the prism and across the plate-boundary. Palinspastic reconstruction of the prism structure based on a seismic line through the drill site, logging data, and lithologic and structural observations of core samples document a single dominant décollement that accommodated almost all of the interplate displacement (~3.2 km) at the drill site. The décollement is located in pelagic clay near the base of the incoming sediment section of the subducting plate, and maintains this stratigraphic position trenchward until it enters the graben below the trench axis where it cuts down-section to follow the basal strata. The structure indicates about half the incoming sediment is offscraped onto the leading edge of the prism but similar amount of sediment may be removed from the base of the frontal prism associated with progressive amplification of horsts and grabens more landward below the prism. The localization of nearly all the interplate displacement to a single narrow décollement composed of sheared pelagic clay indicates the décollement is relatively weak over geologic time. Borehole measurements of temperature across the plate boundary confirm the Tohoku earthquake ruptured the décollement and, consistent with results of high-speed friction experiments on sheared clay, that the décollement is extremely weak during seismic slip. These results, combined with borehole data indicating that the current in situ stress is approximately lithostatic, support the hypothesis that dynamic weakening of wet clay at seismic slip rates favor earthquake rupture propagation to shallow depths even though the frictional properties of wet clay at low slip rates prohibit the nucleation of slip instabilities. Core samples of sheared clay from the décollement are being analyzed to identify earthquake-related microstructures and determine the mechanisms of dynamic weakening during seismic slip.

Textures of water-rich mud sediments from the continental margin offshore Costa Rica (IODP expeditions 334 and 344)

NASA Astrophysics Data System (ADS)

Kuehn, Rebecca; Stipp, Michael; Leiss, Bernd

2017-04-01

During sedimentation and burial at continental margins, clay-rich sediments develop crystallographic preferred orientations (textures) depending on the ongoing compaction as well as size distribution and shape fabrics of the grains. Such textures can control the deformational properties of these sediments and hence the strain distribution in active continental margins and also the frictional behavior along and around the plate boundary. Strain-hardening and discontinuous deformation may lead to earthquake nucleation at or below the updip limit of the seismogenic zone. We want to investigate the active continental margin offshore Costa Rica where the oceanic Cocos plate is subducted below the Caribbean plate at a rate of approximately 9 cm per year. The Costa Rica trench is well-known for shallow seismogenesis and tsunami generation. As it is an erosive continental margin, both the incoming sediments from the Nazca plate as well as the slope sediments of the continental margin can be important for earthquake nucleation and faulting causing sea-floor breakage. To investigate texture and composition of the sediments and hence their deformational properties we collected samples from varying depth of 7 different drilling locations across the trench retrieved during IODP expeditions 334 and 344 as part of the Costa Rica Seismogenesis Project (CRISP). Texture analysis was carried out by means of synchrotron diffraction, as only this method is suitable for water-bearing samples. As knowledge on the sediment composition is required as input parameter for the texture data analysis, additional X-ray powder diffraction analysis on the sample material has been carried out. Samples for texture measurements were prepared from the original drill cores using an internally developed cutter which allows to produce cylindrical samples with a diameter of about 1.5 cm. The samples are oriented with respect to the drill core axis. Synchrotron texture measurements were conducted at the ESRF (European Synchrotron Radiation Facility) in Grenoble and the DESY (German Electron Synchrotron) in Hamburg. Samples were measured in transmission mode perpendicular to their cylinder axis with a beam diameter of 500 µm. Measurements were taken from 0 to 175° in 5° steps resulting in 36 images from a 2D image plate detector. Measurement time was in a range from 1 to 3 seconds. Due to the different, low symmetric mineral phases a large number of mostly overlapping reflections results. Such data can only be analyzed by the Rietveld method, in our case implemented in the software package MAUD (Materials Analysis Using Diffraction). Preliminary results show distinct textures depending on the composition and the origin of the samples, i.e. on drilling location and depth, which may be critical for strain localization and faulting of these samples. The results are also important for the analysis of experimentally deformed samples from the same drill cores which showed structurally weak and structurally strong deformation behavior during triaxial compression.

Paleoceanography of the Bering Sea during the past five million years: results from IODP Expedition 323

NASA Astrophysics Data System (ADS)

Takahashi, K.; Onodera, J.; Asahi, H.; Okazaki, Y.; Kanematsu, Y.; Iwasaki, S.; Ikenoue, T.; Ikehara, M.; Seki, O.; Sakamoto, T.; Horikawa, K.; Khim, B.; Kim, S.; Teraishi, A.; Suto, I.; Ravelo, A. C.

2012-12-01

Based on high quality cores collected by IODP Expedition 323, we reconstructed the paleoceanography of the Bering Sea for the past 5 My. Among 7 sites, two hemipelagic sites drilled to 600 mbsf on Bowers Ridge provided records back to 4.3 Ma at U1341 and 5.0 at U1340, respectively. Two Beringian Slope sites provided the bottom ages of 2.4 Ma at U1343 (745 mbsf) and 0.5 Ma at U1345 (150 mbsf). Analyses of the core samples include microfossils such as diatoms, silicoflagellates, and radiolarians, biogenic opal, δ18O of benthic foraminifers, biomarkers, and neodymium isotopes. During the early Pliocene, siliceous microfossil assemblage analyses and alkenone paleothermometry indicate that relatively warm waters were present in the Bering Sea. Around 3 Ma a decrease in %Stephanopyxis spp., warm water diatoms, is seen, indicating water mass advection from the subarctic Pacific. Fragilariopsis cylindrus, a sea-ice diatom, was present since 2.90 Ma. Initial dominance of silicoflagellate Distephanus medianoctisol is observed at 2.66 Ma. The changes in microfossils assemblages coincide with those observed in alkenone-SST data. The significant intensification of the Northern Hemisphere Glaciation (NHG) at 2.75 Ma appears to be linked to our new data from the Bering Sea. During 2.65-2.0 Ma, prevailing summer stratification due to sea-ice melting is interpreted from an increase of %Actinocyclus spp. Furthermore, the dominance of silicoflagellate Distephanus speculum during 2.4-2.0 Ma suggests a nearly ice-free condition. Changes in %biogenic opal are consistent with what are implied by the siliceous microfossil data. In particular during 2.4-2.0 Ma, the conditions became warmer and more productive than before the NHG. High %Thalassiosira antarctica resting spore after 2 Ma suggests sea-ice formation. Several peaks of %T. antarctica reflects the temporal influence of sea-ice transportation from the Beringian Slope region to Site U1341 after 2 Ma. Dominance of D. medianoctisol during 1.6-2.0 Ma reflects colder environments. The Mid Pleistocene Transition (MPT, ca. 1 Ma) is the time period of interest because of the global change in increased amplitude of warm-cold climatic intervals and shift from 41 k obliquity to 100 k eccentricity cyclicity of glacial-interglacials. During the MPT %Cycladophora davisiana, an intermediate water dwelling radiolarian taxon, increased, indicating increased extent of sea-ice cover. After the MPT since 0.8 Ma, colder conditions are inferred from decreased %N. seminae, abundant %Thalassiosira trifulta group, %T. antarctica, and high% of sea-ice related silicoflagellates. After the MPT, abundant sea-ice related diatoms and silicoflagellates significantly reflect the drifting sea-ice from the Bering Sea shelf. Sea-ice formation at Site U1341 was limited with 1% Fragilaripsis cylindrus while typical seasonal sea-ice area was with greater than 10%.

University of Maine's Follow a Researcher Program™, Expedition 3: Antarctica, Using Graduate Student Fieldwork Experiences as a framework to Incorporate Next Generation Science Standard Practices in the Classroom

NASA Astrophysics Data System (ADS)

Kaluzienski, L. M.; Kranich, G.; Wilson, L.; Hamley, C.

2016-12-01

For the past three years the University of Maine Cooperative Extension 4-H has connected K-12 students in Maine and around the country to UMaine researchers in the field as part of its Follow a Researcher (FAR) Program™. This program aims to provide middle and high school students with a look into future science career paths. FAR™ selects one student engaged in university level research per year to showcase their work. Previous years have selected graduate students with field-work intensive research. During the graduate student's field expedition, a weekly education science video is released based on the Next Generation Science Standards. Similarly, classroom students are encouraged to ask questions during weekly Twitter session hosted live from the field. Past expeditions have taken students to the Quelccaya Ice Cap in Peru as well as the Falkland Islands. This year's expedition shared graduate student Lynn Kaluzienski's expedition to the Ross Ice Shelf in Antarctica. Highlights include obtaining GPS observations in a remote setting using helicopter support, as well acquiring scientific measurements from a heavily crevassed area through the use of robotically towed ground penetrating radar (GPR). Future program plans include connecting K-12 students with graduate students with a focus in lab-intensive research as well as engineering. We also are developing a training program for university outreach staff and a Follow a Researcher™ network that would allow other universities to host their own program while tapping into a larger national K-12 audience.

Integrated bio-magnetostratigraphy of ODP Site 709 (equatorial Indian Ocean).

NASA Astrophysics Data System (ADS)

Villa, Giuliana; Fioroni, Chiara; Florindo, Fabio

2015-04-01

Over the last decade, calcareous nannofossil biostratigraphy of the lower Eocene-Oligocene sediments has shown great potential, through identification of several new nannofossil species and bioevents (e.g. Fornaciari et al., 2010; Bown and Dunkley Jones, 2012; Toffanin et al., 2013). These studies formed the basis for higher biostratigraphic resolution leading to definition of a new nannofossil biozonation (Agnini et al., 2014). In this study, we investigate the middle Eocene-lower Oligocene sediments from ODP Hole 709C (ODP Leg 115) by means of calcareous nannofossils and magnetostratigraphy. Ocean Drilling Program (ODP) Site 709 was located in the equatorial Indian Ocean and biostratigraphy has been investigated in the nineties (Okada, 1990; Fornaciari et al., 1990) while paleomagnetic data from the Initial Report provided only a poorly constrained magnetostratigraphic interpretation, thus the cored succession was dated only by means of biostratigraphy. Our goal is to test the reliability in the Indian Ocean of the biohorizons recently identified at Site 711 (Fioroni et al., in press), by means of high resolution sampling, new taxonomic updates, quantitative analyses on calcareous nannofossils allowed to increase the number of useful bioevents and to compare their reliability and synchroneity. The new magnetostratigraphic analyses and integrated stratigraphy allow also to achieve an accurate biochronology of the time interval spanning Chrons C20 (middle Eocene) and C12 (early Oligocene). In addition, this equatorial site represents an opportunity to study the carbonate accumulation history and the large fluctuations of the carbonate compensation depth (CCD) during the Eocene (e.g. Pälike et al., 2012). The investigated interval encompasses the Middle Eocene Climatic Optimum (MECO), and the long cooling trend that leads to the Oligocene glacial state. By means of our new bio-magnetostratigraphic data and paleoecological results we provide further insights on nannofossil assemblage response to the paleoclimatic changes that led to the Oligocene glacial state. References Agnini, C., Fornaciari, E., Raffi, I., Catanzariti, R., Pälike, H., Backman, J., Rio, D., 2014. Biozonation and biochronology of Paleogene calcareous nannofossils from low and middle latitudes. Newsletters on Stratigraphy, doi:10.1127/0078-0421/2014/0042. Bown, P. R., Dunkley Jones, T., 2012. Calcareous nannofossils from the Paleogene equatorial Pacific (IODP Expedition 320 Sites U1331-1334). Journal of Nannoplankton Research 32(2), 3-51. Fioroni, C., Villa, G., Persico, D., Jovane L. (in press). Middle Eocene-lower Oligocene Calcareous Nannofossil biostratigraphy and paleoceanographic implications from Site 711(equatorial Indian Ocean). Mar. Micropal. Fornaciari, E., Raffi, I., Rio, D., Villa, G., Backman, J., Olaffson, G., 1990. Quantitative distribution patterns of Oligocene and Miocene calcareous nannofossils from the western equatorial Indian Ocean. In: Duncan, R. A., Backman, J., Peterson, L. C., Proceedings of the Ocean Drilling Program, Scientific Resuls, 115, 237-254. Fornaciari, E., Agnini, C., Catanzariti, R., Rio, D., Bolla, E.M. , Valvasoni, E. 2010. Mid-latitude calcareous nannofossil biostratigraphy, biochronology and evolution across the middle to late Eocene transition. Stratigraphy 7, 229-264. Okada, H., 1990. Quaternary and Paleogene calcareous nannofossils, Leg 115. In Duncan, R.A., Backman, J., Peterson, L.C., et al., (Eds), Proceedings ODP, Scientific Results 115, 129-174. College Station, TX: Ocean Drilling Program. Pälike, H. et al., 2012. A Cenozoic record of the equatorial Pacific carbonate compensation depth. Nature 488, 609-615, doi:10.1038/nature11360. Toffanin, F., Agnini, C., Rio, D., Acton, G., Westerhold, T., 2013. Middle Eocene to early Oligocene calcareous nannofossil biostratigraphy at IODP Site U1333(equatorial Pacific). Micropaleontology 59(1), 69-82.

Expedition 26 Docking

NASA Image and Video Library

2010-12-18

Kirk Shireman, second from right, NASA's ISS Deputy Program Manager, is seen at Russian Mission Control in Korolev, Russia speaking to the crew of Expedition 26 shortly after their arrival at the International Space Station on Saturday, Dec. 18, 2010. Photo Credit: (NASA/Carla Cioffi)

Rock magnetic properties in the sulfate reduction zone in IODP 350 Hole 1437B, Izu Bonin rear arc: preliminary results

NASA Astrophysics Data System (ADS)

Musgrave, R. J.; Kars, M. A. C.; Kodama, K.

2014-12-01

During the northern Spring 2014 (April-May), IODP Expedition 350 drilled a 1806.5 m deep hole at Site U1437 in the Izu-Bonin rear arc, in order to understand, among other objectives, the compositional evolution of the arc since the Miocene and track the missing half of the subduction factory. The good recovery of mostly fine grained sediments at this site enables a high resolution paleomagnetic and rock magnetic study. Particularly, variations in magnetic properties and mineralogy are well documented. The onboard magnetostratigraphy established from the study of the archive halves highlighted remagnetized intervals that produced "ghost" repetitions of geomagnetic reversals ~10's meters below their actual stratigraphic position in specific intervals. Onboard paleo- and rock magnetic analyses showed that remagnetization is probably due to a chemical remanence carried by iron sulfides (putatively identified as greigite). The rock magnetic parameters, SIRM/k and the S-ratio are consistent with the presence of ferromagnetic iron sulfides in Site U1437. A mixture of iron oxides and iron sulfides was found within the sulfate reduction zone, which was identified by onboard pore water analyses at ~50-60 meters below sea floor (mbsf) by a minimum in sulfate (~5 mM) coupled with a maximum in alkalinity. Below 50 mbsf, the sulfate content increases up to ~29 mM at ~460 mbsf. The particular downhole profile of the sulfate content in Site U1437 is probably triggered by fluid circulation. Evolution of sulfate content, pyritization process and fluid circulation are closely linked. Onshore research is focusing on further downhole characterization of the iron sulfides including their abundance, grain size and composition. Routine magnetic properties (NRM, magnetic susceptibility) and rock magnetic analyses at high resolution (every ~20-50 cm), including hysteresis properties and low temperature magnetic measurements, have been conducted on about 400 discrete samples in the first 200 m of Hole 1437B (Cores 1H to 30X). As suggested by the onboard data, hysteresis measurements showed the occurrence of both single domain-pseudo single domain iron oxides and iron sulfides in the sulfate reduction zone. Preliminary results will be compared with the geochemical data.

Mediterranean Outflow and surface water variability off southern Portugal during the early Pleistocene: A snapshot at Marine Isotope Stages 29 to 34 (1020-1135 ka)

NASA Astrophysics Data System (ADS)

Voelker, Antje H. L.; Salgueiro, Emilia; Rodrigues, Teresa; Jimenez-Espejo, Francisco J.; Bahr, André; Alberto, Ana; Loureiro, Isabel; Padilha, Maria; Rebotim, Andreia; Röhl, Ursula

2015-10-01

Centennial-to-millennial scale records from IODP Site U1387, drilled during IODP Expedition 339 into the Faro Drift at 558 m water depth, now allow evaluating the climatic history of the upper core of the Mediterranean Outflow (MOW) and of the surface waters in the northern Gulf of Cadiz during the early Pleistocene. This study focuses on the period from Marine Isotope Stages (MIS) 29 to 34, i.e. the interval surrounding extreme interglacial MIS 31. Conditions in the upper MOW reflect obliquity, precession and millennial-scale variations. The benthic δ18O signal follows obliquity with the exception of an additional, smaller δ18O peak that marks the MIS 32/31 transition. Insolation maxima (precession minima) led to poor ventilation and a sluggish upper MOW core, whereas insolation minima were associated with enhanced ventilation and often also increased bottom current velocity. Millennial-scale periods of colder sea-surface temperatures (SST) were associated with short-term maxima in flow velocity and better ventilation, reminiscent of conditions known from MIS 3. A prominent contourite layer, coinciding with insolation cycle 100, was formed during MIS 31 and represents one of the few contourites developing within an interglacial period. MIS 31 surface water conditions were characterized by an extended period (1065-1091 ka) of warm SST, but SST were not much warmer than during MIS 33. Interglacial to glacial transitions experienced 2 to 3 stadial/interstadial cycles, just like their mid-to-late Pleistocene counterparts. Glacial MIS 30 and 32 recorded periods of extremely cold (< 12 °C) SST that in their climatic impact were comparable with the Heinrich events of the mid and late Pleistocene. Glacial MIS 34, on the other hand, was a relative warm glacial period off southern Portugal. Overall, surface water and MOW conditions at Site U1387 show a strong congruence with Mediterranean climate, whereas millennial-scale variations are closely linked to North Atlantic circulation changes.

Record of Subducting Topography revealed in 3D Seismic Imaging of Pleistocene unconformities, offshore Southern Costa Rica

NASA Astrophysics Data System (ADS)

Edwards, J. H.; Kluesner, J. W.; Silver, E. A.

2015-12-01

3D seismic reflection data (CRISP) collected across the southern Costa Rica forearc reveals broad, survey-wide erosional events in the upper ~1 km of slope sediments in the mid-slope to outer shelf. The upper 0-280 m of continuous, weakly deformed sediments, designated by IODP Expedition 344 as structural domain I, is bounded by a major erosional event, (CRISP-U1, dated near 1 Ma), suggesting wave-plain erosion from the present shelf break out to 25 km seaward, to a present-day water depth of 900-1300 m. The eastern toe of its surface is characterized by a large drainage system, likely including submarine channels that eroded to depths >1500 m below present-day water depth. CRISP-U1 is variably uplifted by a series of fault propagation folds and cut by an intersecting array of normal faults. Another, major erosional event, (CRISP-M1, approximately 2 Ma) extended from the outer shelf to the mid slope and removed 500-1000 m of material. Overlying CRISP-M1 is up to 1 km of sediments that are more deformed by fault propagation folds, back thrusts, and intersecting arrays of normal faults. Unconformities with smaller areal extent are variably found in these overlying sediments across the mid-slope to outer shelf, at present-day water depths >220 m. Below CRISP-M1, sediments are more densely deformed and also contain major unconformities that extend survey-wide. Both unconformities, CRISP-U1 and CRISP-M1, are encountered in well U1413 and are demarcated by major benthic foraminifera assemblage changes at 149 mbsf and ~504 mbsf (Harris et al., 2013, Proceeding of the IODP, Volume 344).CRISP-M1 is likely correlative to the major sediment facies and benthic foraminifera assemblage change found in U1379 at ~880 mbsf (Vannuchi et al., 2013). The unconformities and intersecting array of normal faults may demarcate the passing of topography on the downgoing Cocos plate, episodically lifting and then subsiding the Costa Rica margin, with amplitudes up to about 1 km.

Amphibole and felsic veins from the gabbroic oceanic core complex of Atlantis Bank (Southwest Indian Ridge, IODP Hole U1473A): when the fluids meets the melts

NASA Astrophysics Data System (ADS)

Sanfilippo, A.; Tribuzio, R.; Antonicelli, M.; Zanetti, A.

2017-12-01

We present a petrological/geochemical investigation of brown amphibole and felsic veins drilled during IODP 360 expedition at Atlantis Bank, a gabbroic oceanic core complex from Southwest Indian Ridge. The main purpose of this study is to unravel the role of seawater and magmatic components in the origin of these veins. Brown amphibole veins were collected at 90-170 mbsf. These veins typically include minor modal amounts of plagioclase and are associated with alteration halos made up of brown amphibole and whitish milky plagioclase in host gabbros. Two sets of late magmatic felsic veins, which mostly consist of plagioclase and minor brown amphibole, were selected. Amphibole-plagioclase geothermometry (Holland and Blundy, 1994) documents that crystallization of brown amphibole and felsic veins occurred in the 850-700 °C interval. In the brown amphibole veins, amphibole and plagioclase have relatively low concentrations of incompatible trace elements and significant Cl (0.2-0.3 wt%). The development of these veins at near surface levels is therefore attributed to seawater-derived fluids migrating downward through cracks developing in the exhuming gabbro. To explain the high temperature estimates for the development of these shallow veins, however, the seawater-derived fluids must have interacted not only with the gabbros, but also with a high temperature magmatic component. This petrogenetic hypothesis is consistent with oxygen and hydrogen isotopic compositions of amphiboles from shallow veins in adjacent Hole 735B gabbros (Alt and Bach, 2006). Trace element compositions of amphibole and plagioclase from the felsic veins show formation by silicate melts rich in incompatible elements. In addition, Cl concentrations in amphibole from the felsic veins are low, thereby indicating that the melts feeding these veins had low or no seawater component. We cautiously propose that: (i) the felsic veins were generated by SiO2-rich melts residual after crystallization of Fe-Ti-oxide phases, and (ii) the brown amphibole veins were generated by interaction of seawater-derived fluids with the late-stage residual melts rising through the gabbroic sequence.

Changing sediment physical properties at the Agulhas Plateau (IODP Site U1475): indications for the long-term variability of deepwater circulation over the last 7 Ma

NASA Astrophysics Data System (ADS)

Gruetzner, Jens; Lathika, Nambiyathodi; Jimenez Espejo, Francisco J.; Uenzelmann-Neben, Gabriele

2017-04-01

The gateway south of South Africa constitutes an integral inter-ocean link in the global thermohaline circulation (THC) since it allows the exchange of shallow- and deepwater masses between the Indian and the Atlantic. Thus understanding past variations of this current system is important for improving our knowledge of the global climate. The long-term changes in deepwater flow in the Atlantic-Indian gateway during the Cenozoic have been initially studied using reflection seismic profiles. But in many cases the seismic stratigraphy is poorly constrained and not further resolved within the time period from the late Miocene to present. In particular, there are limited Pliocene records that can be used to investigate the influence of climatic (e.g. Antartic ice volume) and tectonic (e.g. closure of the central American seaway) on the deep-water variability. Here we focus on the bottom water flow around the Agulhas Plateau, a location proximal to the entrance of North Atlantic Deep Water (NADW) to the Southern Ocean and South Indian Ocean. IODP Expedition 361 (SAFARI) Site U1475 was drilled in 2669 m water depth into a sediment drift that is deposited on the southwestern flank of Agulhas Plateau and comprises a complete stratigraphic section of the last 7 Ma. We present cleaned, edited, and spliced high-resolution data sets of sediment physical properties measured at Site U1475. Synthetic seismograms generated from the velocity and bulk density core scanning records allow a detailed correlation oft the drilling results with the Site survey seismic reflection profiles. Seismic reflectors at 3.75 and 3.87 s (two-way-traveltime) correspond to major increases in acoustic impedance at 110 and 216 meters below seafloor. Based on the preliminary shipboard biostratigraphic age model sediments at these depths have ages of 4.0 and 5.1 Ma, respectively. Furthermore spectral analyses of physical property records such as natural gamma radiation and colour reflectance reveal climate variability on orbital and suborbital timescales.

Long-term variations of clay mineral composition in the Andaman Sea (IODP Exp. 353 Site U1447): preliminary result

NASA Astrophysics Data System (ADS)

Lee, J.; Khim, B. K.; Cho, H. G.; Kim, S.; 353 Scientists, I. E.

2016-12-01

Clay mineral studies in the Bengal Fan have allowed the reconstruction of the erosional history of the Himalayan-Tibetan complex since the Early Miocene. Several factors such as climate change and tectonic activity are important for the erosion rate of the Himalaya-Tibet complex. IODP Expedition 353 Site U1447 (10°47.4'N, 93°00'E; 1391 mbsl) was drilled on a ridge 45 km offshore Little Andaman Island in the Andaman Sea, penetrating to total depths of 738 m. Riverine sediments supplied mainly by the Irrawaddy and Salween (draining the Indo-Burman Ranges; smectite-rich) and the Ganga/Brahmaputra (draining the Himalaya; illite-rich) via the surface currents have been known to deposit in the Andaman Sea. We measured clay minerals of 38 sediment samples collected from 150 to 737 m CSF-A at Site U1447 in order to reveal long-term variation patterns of clay minerals and their controlling factors. Age reconstruction of Site U1447 aided by shipboard biostratigraphic and paleomagnetic data defined the study interval spanning from the Late Miocene ( 10 Ma) to Early Pleistocene ( 1.25 Ma). At this interval, clay minerals consist mainly of smectite (28-61% with an average of 47%) followed by illite (20-41% with an average of 29%), kaolinite (9-19% with an average of 14%), and chlorite (5-15% with an average of 10%). Variation of clay mineral compositions is divided into three stages; almost consistent variations of all clay minerals (from 750 to 570 m CSF-A; 10.0 to 7.5 Ma), gradual decrease of smectite and increase of illite and chlorite (from 570 to 400 m CSF-A; 7.5 to 4.5 Ma), and great fluctuation of all clay minerals (from 400 to 150 m CSF-A; 4.5 to 1.1 Ma). Such long-term clay mineral changes may be related to provenance switches, tectonic evolution of the source regions, climatic variations, degree of volcanism with basin evolution, sedimentation history by sea level changes or some combination of these factors.

The Distribution and Appearance of Cold-Water Coral Carbonate Mounds and Mound-Like Structures in the NE Atlantic: Pre-site Appraisal for CARBONATE Drilling

NASA Astrophysics Data System (ADS)

Dorschel, B.; Wheeler, A. J.; Monteys, X.

2007-12-01

Cold-water coral carbonate mounds on the continental slope of the northeast Atlantic are certainly among the most amazing geological discoveries of the last decade. They developed as a result of hydrological, biological and geological processes with thickets of cold-water corals mainly Lophelia pertus and Madrepora oculata reported from numerous mound sites. Over the last years, research focused on selected mounds e.g. IODP Sites 1317 visited during IODP Expedition 307 has revealed that many of the investigated mounds are true coral built-ups. The recovered mound sediments were composed of loose coral frameworks embedded in a matrix of fine grained hemipelagic sediments. The additional calcium carbonate added by the corals was in the form of fragments and bioeroded fine grained carbonate flakes. This increase in calcium carbonate classifies the mounds as spots of enhanced carbonate accumulation in intermediate water depth. So far, the carbonate stored in submarine carbonate mounds in the northeast Atlantic has not been included in any carbon budget estimations. This was mainly due to the lack of information on the abundance and distribution of those mounds. The recently available high resolution multi-beam bathymetry data recorded during the Irish National Seabed Survey (INSS) allows, for the first time, a mapping of these mounds and mound-like structures enabling an estimation of their abundance and quantification of their contribution to continental slope sediments. Here, we present the first comprehensive overview and quantification of mounds and mound-like structures based on 25m rastered bathymetric data for the Irish sector of the NE Atlantic. Based on the data, we identified over 1600 mound-like structures along the NE Atlantic slope between 46°45'N and 57°30'N. The structures elevate up to 300m above the surrounding seafloor and were usually grouped into distinct provinces often associated with erosive structures such as canyons and moats. 90% of the identified features occurred in water depth between 500 and 1500m. Assessment of this data will be used to target mounds for drilling during the ESF CARBONATE project.

Miocene denudation history of Himalaya deduced from IODP Exp. 354 Bengal Fan

NASA Astrophysics Data System (ADS)

Kohki, Y.; Cruz, J. W.; Osaki, A.; Manoj, M. C.; Hatano, N.; France-Lanord, C.; Spiess, V.; Klaus, A.

2017-12-01

The submarine Bengal Fan is the largest submarine fan on Earth and covers the whole Bay of Bengal. The sediments are fed by the Ganges and Brahmaputra rivers reflecting India-Asia plate collision. The sediments recovered from IODP Expedition 354 Bengal Fan record the uplift history of the Himalayan orogenic system. We examined the chemical composition of detrital garnets in the Miocene deposits from Site U1451, where drilling reached to basal horizon of the fan deposits, in order to reveal the detailed denudation history of Himalayan metamorphic rocks. For this purpose, the comparison of chemical composition between detrital garnet in the Bengal Fan deposits and metamorphic garnet in Himalayan metamorphic rocks was carried out. The chemical composition of the metamorphic garnet from Higher Himalayan Crystalline (HHC) in Karnali and Kaligandaki areas, western Nepal, was examined for chemical reference to detrital garnets in Bengal Fan. The metamorphic garnets in "Formation I (Le Fort, 1975)" in HHC are characterized by almandine-rich garnet with high pyrope content. Also, the garnets in "Formation II" are remarked by two types of garnets, i.e., almandine-rich and grandite-rich garnets. Meanwhile, the composition of garnets in "Formation III" is almandine-rich garnet with low pyrope content. In the Bengal Fan deposits, the characteristic garnets, which show the similarity to the metamorphic garnet in HHC, is not found from the Lower Miocene (Burdigalian) deposits. In the Middle and Upper Miocene deposits, the almandine-rich garnets characteristic in Formation I, are normally included. At the basal part of the Middle Miocene (Langhian), almandine-rich garnets with low pyrope content, suggesting the derivation from Formation III, are remarkable. The grandite-rich garnets from Formation II are sporadically found In the Upper Miocene deposits (Tortonian-Messinian). Above chemical comparison between the detrital garnets in Bengal Fan and metamorphic garnets from HHC demonstrates that exposure and sediment production started from Formation III in HHC in onset of the Middle Miocene time. The wide exposure of HHC was propagated to Formation I and II until the Middle Miocene period.

Long Term Observations of Subsurface Pore Pressure in the Kumano Basin and Upper Accretionary Wedge along the NanTroSIEZE Transect, offshore Japan: Signals from the 2011 Tohoku Earthquake

NASA Astrophysics Data System (ADS)

Zhang, Y.; Saffer, D. M.

2013-12-01

Subsurface pore pressure as a sensitive measure of strain and formation properties has provided insights into the wide range of fault slip behaviors, contributing to the understanding of fault and earthquake mechanics. Pore pressures from off shore borehole observatory are especially important, as 1) they are the only detectable signals of small and slow events; 2) they provide our only access to the outer forearc, where the tsunami hazards are triggered by the fault slip. As part of the Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) a suite of borehole sensors were installed as part of a long-term borehole observatory at IODP Site C0002, during IODP Expedition # 332 in December of 2010. The observatory includes a broadband seismometer, short period geophones, a volumetric strainmeter, temperature sensors, an accelerometer, and formation pore pressure monitoring at two depths: one in the mudstones of the Kumano Basin in an interval spanning 757-780 meters below seafloor (mbsf), and a second in the uppermost accretionary wedge in an interval from 937 - 980 mbsf. Here, we report on pore pressure records acquired at a sampling frequency of 1/60 Hz, spanning the period from December 2010 to January 2013, which were recovered in early 2013. We observe a clear hydraulic signal from March 11, 2011 Tohoku earthquake and aftershocks, including both dynamic pore pressure changes during passage of surface waves and shifts in formation pressure following the event. Pressure exhibit an increase of ~3 kPa in the upper sediment screened interval following the earthquake, and decrease by ~5 kPa in the accretionary prism interval. Both of the offset changes persist through the end of the data recording. These pore pressure changes may reflect static stress changes from the earthquake, or local site effects related to shaking. We also observe a clear increase in formation pore pressures associated with drilling operations at nearby holes in November and December 2012. These inadvertent two-well tests provide information about formation hydraulic properties at the ~20-50 m scale.

Inter-linkages of SE Asian, Indian and Indonesian-Australian monsoonal subsystems on orbital and suborbital timescales

NASA Astrophysics Data System (ADS)

Holbourn, A. E.; Kuhnt, W.; Tada, R.; Murray, R. W.; Alvarez Zarikian, C. A.; Clemens, S. C.

2014-12-01

The SE Asian, Indian and Indonesian-Australian monsoonal subsystems are closely inter-linked, but show substantial differences in the spatial and temporal distribution of precipitation, mainly due to contrasting land-sea distribution and high latitude control. We explore changes in these subsystems in relation to high latitude climate variability on suborbital and orbital timescales, focusing on the last deglaciation and the long-term Miocene evolution. Our main proxies are δ18O and Mg/Ca based salinity and temperature reconstructions in combination with sedimentary and geochemical runoff signatures. Key issues are the synchroneity of monsoonal precipitation changes in relation to northern and southern hemisphere insolation and the response of individual subsystems to atmospheric CO2 and global ice volume variations. In contrast to northern hemisphere monsoonal records, the deglacial intensification of the Australian summer monsoon paralleled southern hemisphere climate evolution. We hypothesize that intensification of the summer heat low over the Australian continent through enhanced greenhouse forcing accentuated the southward pull of the Intertropical Convergence Zone (ITCZ). Additional forcing mechanisms including the variability of the Walker circulation and Indian Ocean Dipole, the heat and moisture transfer from the tropical Indian Ocean and deglacial sea-level changes remain highly debated. High-resolution Miocene records from the South China Sea (ODP Site 1146) indicate that the latitudinal displacement of the ITCZ also impacted the long-term development of the SE Asian summer monsoon. Antarctic ice growth episodes at 14.6, 14.2, 13.9, and 13.1 Ma coincided with surface warming and freshening, implying high sensitivity of tropical rain belts to the inter-hemispheric temperature gradient. However, comparable records of the long-term evolution of the Indian and Indonesian-Australian monsoonal subsystems that would allow testing of this hypothesis are still missing. High-resolution sedimentary archives recently recovered during IODP Expedition 346 (Asian Monsoon) and to be drilled during IODP Exp 353 (Indian Monsoon) will enable direct comparison of the three monsoonal subsystems and reconciliation of linkages between marine and land records.

ISS Expedition 42 Crew Profile, Version 2

NASA Image and Video Library

2014-11-26

Narrated production with biographical information about ISS Expedition 42 crewmembers Barry "Butch" Wilmore, Alexander Samokutyaev, Elena Serova, Terry Virts, Anton Shkaplerov and Samantha Cristoforetti. The program covers the crewmember's career including childhood photographs, previous space missions and interview sound bites with the crewmembers.

7 CFR 1703.112 - Expedited telecommunications loans

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 11 2010-01-01 2010-01-01 false Expedited telecommunications loans 1703.112 Section 1703.112 Agriculture Regulations of the Department of Agriculture (Continued) RURAL UTILITIES SERVICE, DEPARTMENT OF AGRICULTURE RURAL DEVELOPMENT Distance Learning and Telemedicine Loan and Grant Program-General...

Semantic Approaches Applied to Scientific Ocean Drilling Data

NASA Astrophysics Data System (ADS)

Fils, D.; Jenkins, C. J.; Arko, R. A.

2012-12-01

The application of Linked Open Data methods to 40 years of data from scientific ocean drilling is providing users with several new methods for rich-content data search and discovery. Data from the Deep Sea Drilling Project (DSDP), Ocean Drilling Program (ODP) and Integrated Ocean Drilling Program (IODP) have been translated and placed in RDF triple stores to provide access via SPARQL, linked open data patterns, and by embedded structured data through schema.org / RDFa. Existing search services have been re-encoded in this environment which allows the new and established architectures to be contrasted. Vocabularies including computed semantic relations between concepts, allow separate but related data sets to be connected on their concepts and resources even when they are expressed somewhat differently. Scientific ocean drilling produces a wide range of data types and data sets: borehole logging file-based data, images, measurements, visual observations and the physical sample data. The steps involved in connecting these data to concepts using vocabularies will be presented, including the connection of data sets through Vocabulary of Interlinked Datasets (VoID) and open entity collections such as Freebase and dbPedia. Demonstrated examples will include: (i) using RDF Schema for inferencing and in federated searches across NGDC and IODP data, (ii) using structured data in the data.oceandrilling.org web site, (iii) association through semantic methods of age models and depth recorded data to facilitate age based searches for data recorded by depth only.

Lunar precursor missions for human exploration of Mars--III: studies of system reliability and maintenance.

PubMed

Mendell, W W; Heydorn, R P

2004-01-01

Discussions of future human expeditions into the solar system generally focus on whether the next explorers ought to go to the Moon or to Mars. The only mission scenario developed in any detail within NASA is an expedition to Mars with a 500-day stay at the surface. The technological capabilities and the operational experience base required for such a mission do not now exist nor has any self-consistent program plan been proposed to acquire them. In particular, the lack of an Abort-to-Earth capability implies that critical mission systems must perform reliably for 3 years or must be maintainable and repairable by the crew. As has been previously argued, a well-planned program of human exploration of the Moon would provide a context within which to develop the appropriate technologies because a lunar expedition incorporates many of the operational elements of a Mars expedition. Initial lunar expeditions can be carried out at scales consistent with the current experience base but can be expanded in any or all operational phases to produce an experience base necessary to successfully and safely conduct human exploration of Mars. Published by Elsevier Ltd.

Lunar precursor missions for human exploration of Mars--III: studies of system reliability and maintenance

NASA Technical Reports Server (NTRS)

Mendell, W. W.; Heydorn, R. P.

2004-01-01

Discussions of future human expeditions into the solar system generally focus on whether the next explorers ought to go to the Moon or to Mars. The only mission scenario developed in any detail within NASA is an expedition to Mars with a 500-day stay at the surface. The technological capabilities and the operational experience base required for such a mission do not now exist nor has any self-consistent program plan been proposed to acquire them. In particular, the lack of an Abort-to-Earth capability implies that critical mission systems must perform reliably for 3 years or must be maintainable and repairable by the crew. As has been previously argued, a well-planned program of human exploration of the Moon would provide a context within which to develop the appropriate technologies because a lunar expedition incorporates many of the operational elements of a Mars expedition. Initial lunar expeditions can be carried out at scales consistent with the current experience base but can be expanded in any or all operational phases to produce an experience base necessary to successfully and safely conduct human exploration of Mars. Published by Elsevier Ltd.

Causes and consequences of the great strength variability among soft Nankai accretionary prism sediments from offshore SW-Japan

NASA Astrophysics Data System (ADS)

Stipp, Michael; Schumann, Kai; Leiss, Bernd; Ullemeyer, Klaus

2014-05-01

The Nankai Trough Seismogenic Zone Experiment of the International Ocean Discovery Program (IODP) is the very first attempt to drill into the seismogenic part of a subduction zone. Offshore SW-Japan the oceanic Philippine sea plate is subducted beneath the continental Eurasian plate causing earthquakes of magnitude 8.0 to 8.5 and related tsunamis with a recurrence rate of 80-100 years. For the tsunamigenic potential of the forearc slope and accreted sediments their mechanical strength, composition and fabrics have been investigated. 19 drill core samples of IODP Expeditions 315, 316 and 333 were experimentally deformed in a triaxial cell under consolidated and undrained conditions at confining pressures of 400-1000 kPa, room temperature, axial shortening rates of 0.01-9.0 mm/min, and up to an axial strain of ˜64% (Stipp et al., 2013). With respect to the mechanical behavior, two distinct sample groups could be distinguished. Weak samples from the upper and middle forearc slope of the accretionary prism show a deviatoric peak stress after only a few percent strain (< 10%) and a continuous stress decrease after a maximum combined with a continuous increase in pore pressure. Strong samples from the accretionary prism toe display a constant residual stress at maximum level or even a continuous stress increase together with a decrease in pore pressure towards high strain (Stipp et al., 2013). Synchrotron texture and composition analysis of the experimentally deformed and undeformed samples using the Rietveld refinement program MAUD indicates an increasing strength of the illite and kaolinite textures with increasing depth down to 523 m below sea floor corresponding to a preferred mineral alignment due to compaction. Experimentally deformed samples have generally stronger textures than related undeformed core samples and they show also increasing strength of the illite and kaolinite textures with increasing axial strain. Mechanically weak samples have a bulk clay plus calcite content of 31-65 vol.-% and most of their illite, kaolinite, smectite and calcite [001]-pole figures have maxima >1.5 mrd. Strong samples which were deformed to approximately the same amount of strain (up to 40%) have no calcite and a bulk clay content of 24-36 vol.-%. Illite, kaolinite and smectite [001]-pole figure maxima are mostly <1.5 mrd, except for one sample which was deformed to a considerably higher strain (64%). The higher clay and calcite content and the stronger textures of the mechanically weak samples can be related to a collapsing pore space of the originally flocculated clay aggregates. This process is insignificant in the strong samples from the prism toe, for which deformation would tend to involve large rock volumes and lead to strain dissipation. The weak samples from the forearc slope which become even weaker with increasing strain may provoke mechanical runaway situations allowing for earthquake rupture, surface breakage and tsunami generation. Stipp, M., Rolfs, M., Kitamura, Y., Behrmann, J.H., Schumann, K., Schulte-Kortnack, D. and Feeser, V. 2013. G-Cubed 14/11, doi: 10.1002/ggge.20290.

KSC-2014-4111

NASA Image and Video Library

2014-09-25

CAPE CANAVERAL, Fla. – NASA Kennedy Space Center Director and former astronaut Bob Cabana, right, introduces astronaut Rick Mastracchio to the audience at a post-flight presentation on the Expedition 38 mission to the International Space Station. The Space Flight Awareness Program hosted Mastracchio's presentation for employees in the KSC Training Auditorium. An Expedition 38/39 crew member, Mastracchio launched to the station from the Baikonur Cosmodrome in Kazakhstan on Nov. 6, 2013, and returned to Earth on May 13, 2014, after 188 days in space. Following Mastracchio's remarks, employees were given the opportunity to ask questions and to meet him in person. To read Mastracchio's biography, visit http://www.jsc.nasa.gov/Bios/htmlbios/mastracc.html. For more information on Expedition 38, visit http://www.nasa.gov/mission_pages/station/expeditions/expedition38. Photo credit: NASA/Daniel Casper

KSC-2014-4113

NASA Image and Video Library

2014-09-25

CAPE CANAVERAL, Fla. – NASA astronaut Rick Mastracchio makes his opening remarks to the audience at a post-flight presentation on the Expedition 38 mission to the International Space Station. The Space Flight Awareness Program hosted Mastracchio's presentation for employees in the KSC Training Auditorium at NASA's Kennedy Space Center in Florida. An Expedition 38/39 crew member, Mastracchio launched to the station from the Baikonur Cosmodrome in Kazakhstan on Nov. 6, 2013, and returned to Earth on May 13, 2014, after 188 days in space. Following Mastracchio's remarks, employees were given the opportunity to ask questions and to meet him in person. To read Mastracchio's biography, visit http://www.jsc.nasa.gov/Bios/htmlbios/mastracc.html. For more information on Expedition 38, visit http://www.nasa.gov/mission_pages/station/expeditions/expedition38. Photo credit: NASA/Daniel Casper

KSC-2014-4114

NASA Image and Video Library

2014-09-25

CAPE CANAVERAL, Fla. – NASA astronaut Rick Mastracchio discusses the highlights of the Expedition 38 mission to the International Space Station with the audience at a post-flight presentation. The Space Flight Awareness Program hosted Mastracchio's presentation for employees in the KSC Training Auditorium at NASA's Kennedy Space Center in Florida. An Expedition 38/39 crew member, Mastracchio launched to the station from the Baikonur Cosmodrome in Kazakhstan on Nov. 6, 2013, and returned to Earth on May 13, 2014, after 188 days in space. Following Mastracchio's remarks, employees were given the opportunity to ask questions and to meet him in person. To read Mastracchio's biography, visit http://www.jsc.nasa.gov/Bios/htmlbios/mastracc.html. For more information on Expedition 38, visit http://www.nasa.gov/mission_pages/station/expeditions/expedition38. Photo credit: NASA/Daniel Casper

KSC-2014-4110

NASA Image and Video Library

2014-09-25

CAPE CANAVERAL, Fla. – NASA Kennedy Space Center Director and former astronaut Bob Cabana, right, welcomes astronaut Rick Mastracchio to the center for a post-flight presentation on the Expedition 38 mission to the International Space Station. The Space Flight Awareness Program hosted Mastracchio's presentation for employees in the KSC Training Auditorium. An Expedition 38/39 crew member, Mastracchio launched to the station from the Baikonur Cosmodrome in Kazakhstan on Nov. 6, 2013, and returned to Earth on May 13, 2014, after 188 days in space. Following Mastracchio's remarks, employees were given the opportunity to ask questions and to meet him in person. To read Mastracchio's biography, visit http://www.jsc.nasa.gov/Bios/htmlbios/mastracc.html. For more information on Expedition 38, visit http://www.nasa.gov/mission_pages/station/expeditions/expedition38. Photo credit: NASA/Daniel Casper

KSC-2014-4112

NASA Image and Video Library

2014-09-25

CAPE CANAVERAL, Fla. – NASA Kennedy Space Center Director and former astronaut Bob Cabana, right, introduces astronaut Rick Mastracchio to the audience at a post-flight presentation on the Expedition 38 mission to the International Space Station. The Space Flight Awareness Program hosted Mastracchio's presentation for employees in the KSC Training Auditorium. An Expedition 38/39 crew member, Mastracchio launched to the station from the Baikonur Cosmodrome in Kazakhstan on Nov. 6, 2013, and returned to Earth on May 13, 2014, after 188 days in space. Following Mastracchio's remarks, employees were given the opportunity to ask questions and to meet him in person. To read Mastracchio's biography, visit http://www.jsc.nasa.gov/Bios/htmlbios/mastracc.html. For more information on Expedition 38, visit http://www.nasa.gov/mission_pages/station/expeditions/expedition38. Photo credit: NASA/Daniel Casper

KSC-2014-4109

NASA Image and Video Library

2014-09-25

CAPE CANAVERAL, Fla. – NASA Kennedy Space Center Director and former astronaut Bob Cabana, left, greets astronaut Rick Mastracchio before the start of a post-flight presentation on the Expedition 38 mission to the International Space Station. The Space Flight Awareness Program hosted Mastracchio's presentation for employees in the KSC Training Auditorium. An Expedition 38/39 crew member, Mastracchio launched to the station from the Baikonur Cosmodrome in Kazakhstan on Nov. 6, 2013, and returned to Earth on May 13, 2014, after 188 days in space. Following Mastracchio's remarks, employees were given the opportunity to ask questions and to meet him in person. To read Mastracchio's biography, visit http://www.jsc.nasa.gov/Bios/htmlbios/mastracc.html. For more information on Expedition 38, visit http://www.nasa.gov/mission_pages/station/expeditions/expedition38. Photo credit: NASA/Daniel Casper

Expedition 23 State Commission

NASA Image and Video Library

2010-03-31

Kirk Shireman, NASA's deputy ISS program manager, speaks during the State Commission meeting to approve the Soyuz launch of Expedition 23 Soyuz Commander Alexander Skvortsov, Flight Engineer Tracy Caldwell Dyson and Flight Engineer Mikhail Kornienko on Thursday, April 1, 2010, in Baikonur, Kazakhstan. Photo Credit: (NASA/Carla Cioffi)

Mineral-Association and Activity of Bacteria and Archaea in the Deep Subsurface South Pacific Gyre Sediment

NASA Astrophysics Data System (ADS)

Steele, J. A.; Dekas, A. E.; Harrison, B. K.; Morono, Y.; Inagaki, F.; Ziebis, W.; Orphan, V. J.

2012-12-01

Although the subsurface biosphere is now recognized as an important reservoir of life on our planet, until recently the microbial community beneath open-ocean oligotrophic gyres (making up the majority of the seafloor) has just begun to be studied in detail. IODP Expedition 329 and the KNOX-022RR site survey cruise have taken some of the first steps at characterizing the microbial community beneath the South Pacific Gyre, a region with low organic carbon burial rates (10-8 and 10-10 moles C cm-1 yr-1), deep oxygen penetration (sediments are oxidized to the basement), and low prokaryotic cell counts (106 cells cm-3 to <103 cells cm-3). In these sediments, the dominant fraction of organic carbon may be aggregated or adsorbed to minerals, suggesting that microbes that are able to grow on the minerals may create potential "hotspots" of activity. In this study, we performed magnetic separation on oligotrophic sediment samples and examined the bacterial and archaeal communities using 16S rRNA tag sequencing. To determine if the mineral-associated cells were autotrophic and/or utilizing nitrate, we performed long-term (20 month) incubations with 13CO2 and 15NO3- from sediment taken at depths ~2-70 mbsf beneath the oligotrophic gyre and outside of the oligotrophic gyre (IODP Exp. 329 stations U1368-U1371). Subsequently we used the DNA stain SYBR Green I, and CARD-FISH-NanoSIMS to identify cells which were actively taking up the isotopic label. We then used SEM-EDS to identify the mineral particle composition. Preliminary results found the magnetic fraction in oligotrophic sediment (KNOX-022RR station SPG-5) from 1.2-2.6 mbsf showed a greater diversity of both bacteria and archaea. OTUs from Chloroflexi groups SO85 and SAR202 were dominant in the magnetic fraction. Firmicutes, Bacteroidetes, δ-Proteobacteria, Verrucomicrobia, Deferribacteres, WS3, OP10, and OP1 OTUs were found only in the magnetic fraction. Crenarchaeal OTUs from Marine Benthic Group B and Marine Group I (Thaumarchaea) and Euryarchaeal OTUs from Methanomicrobia and Thermococcus groups were found in the magnetic fraction with Marine Group I Crenarchaea showing the highest archaeal abundance. The higher diversity in the magnetic fraction suggests that bacteria and archaea associated with Fe-rich or Mn-rich minerals may be able to exploit a wider array of niches. Comparing sediment from within and outside the gyre, the more productive sediments had greater total cell numbers; however, we observed an increase in attached cells in the relatively Fe and P-rich samples (the heavy fraction) in the oligotrophic sediments (IODP Exp. 329 station U1368 and KNOX-022RR station SPG-6), suggesting a possible preference for attachment to Fe and P-rich particles.

Research activities on submarine landslides in gentle continental slope

NASA Astrophysics Data System (ADS)

Morita, S.; Goto, S.; Miyata, Y.; Nakamura, Y.; Kitahara, Y.; Yamada, Y.

2013-12-01

In the north Sanrikuoki Basin off Shimokita Peninsula, NE Japan, a great number of buried large slump deposits have been identified in the Pliocene and younger formations. The basin has formed in a very gentle continental slope of less than one degree in gradient and is composed of well-stratified formations which basically parallel to the present seafloor. This indicates that the slumping have also occurred in such very gentle slope angle. The slump units and their slip surfaces have very simple and clear characteristics, such as layer-parallel slip on the gentle slope, regularly imbricated internal structure, block-supported with little matrix structure, widespread dewatering structure, and low-amplitude slip surface layer. We recognize that the large slump deposits group of layer-parallel slip in this area is an appropriate target to determine 'mechanism of submarine landslides', that is one of the subjects on the new IODP science plan for 2013 and beyond. So, we started some research activities to examine the feasibility of the future scientific drilling. The slump deposits were recognized basically by 3D seismic analysis. Further detailed seismic analysis using 2D seismic data in wider area of the basin is being performed for better understanding of geologic structure of the sedimentary basin and the slump deposits. This will be good source to extract suitable locations for drill sites. Typical seismic features and some other previous studies imply that the formation fluid in this study area is strongly related to natural gas, of which condition is strongly affected by temperature. So, detailed heat flow measurements was performed in the study area in 2013. For that purpose, a long-term water temperature monitoring system was deployed on the seafloor in October, 2012. The collected water temperature variation is applied to precise correction of heat flow values. Vitrinite reflectance analysis is also being carried out using sediments samples recovered by IODP Expedition 337, which is conducted in a part of the study area from July through September in 2012. The values of vitrinite reflectance will be available for modeling thermal history in the sedimentary basin. A science meeting and a field trip were held in Miyazaki Prefecture in September , 2012. At the field trip, we observed typical geologic structures related to slumping and dewatering in Nichinan Group, which are good onshore objects so as to share the aspects of the slump deposits in the Sanrikuoki Basin among the community. This occasion is aimed at sharing better scientific understanding on slumping and related dewatering and also at identifying the issues for planning the scientific drilling. This study uses the 3D seismic data from the METI seismic survey 'Sanrikuoki 3D' in 2008. The seismic analysis, the vitrinite reflectance analysis, and the science meeting and the field excursion in Miyazaki were supported by the foundation of feasibility studies for future IODP scientific drillings by JAMSTEC CDEX in 2012-2013.

An Environmental Expedition Course in Search of the Maya.

ERIC Educational Resources Information Center

Loret, John

1978-01-01

Sponsoring an interdisciplinary program (over 30 lecture hours of geology, ecology, anthropology, ethnology, and agriculture of the Yucatan and Meso-America), Queens College and the University of Connecticut provide expeditions to Mexico and study of local geomorphology, stratigraphy, climate, topography, soils, archeological sites, flora, and…

New Capabilities and Future Downhole and Coring Tools for IODP

NASA Astrophysics Data System (ADS)

Skinner, A.

2001-05-01

The extremely successful Ocean Drilling Programme (ODP) set the scene for innovative technical solutions to meet scientific challenges. This scenario is set to expand when the Integrated Ocean Drilling Programme (IODP) comes on stream at the end of 2003. Firstly the programme will have access to two dedicated drilling vessels and additional `Fit to mission@ offshore drilling units. This will allow for a much wider base of scientific disciplinary objectives to be met by coring and geophysical logging. And in turn will require more and innovative techncial equipment to collect the data. Secondly there are a number of coring tool developments which can enhance and extend data collection and which are not currently being used within the ODP programme. This, coupled with the different operational capabilities within IODP poses a number of technical challenges to ensure that the new programme meets all of the anticipated scientific demands. Thridly, over the past few years and ongoing at an accelerated pace, there has been significant advances in remote geophysical logging of boreholes both during and after drilling. The full potential of this has yet to be released on the scientific community and is set to revolutionise the acquisition of data from scientific boreholes. All of these items are discussed in the context of meeting the scientific challenges of IODP by harnessing and developing present industry and (outwith ODP) scientific technologies for the new programme.

42 CFR 8.28 - Expedited procedures for review of immediate suspension.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 42 Public Health 1 2013-10-01 2013-10-01 false Expedited procedures for review of immediate suspension. 8.28 Section 8.28 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL PROVISIONS CERTIFICATION OF OPIOID TREATMENT PROGRAMS Procedures for Review of Suspension or...

42 CFR 8.28 - Expedited procedures for review of immediate suspension.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 42 Public Health 1 2012-10-01 2012-10-01 false Expedited procedures for review of immediate suspension. 8.28 Section 8.28 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL PROVISIONS CERTIFICATION OF OPIOID TREATMENT PROGRAMS Procedures for Review of Suspension or...

42 CFR 8.28 - Expedited procedures for review of immediate suspension.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 42 Public Health 1 2014-10-01 2014-10-01 false Expedited procedures for review of immediate suspension. 8.28 Section 8.28 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL PROVISIONS CERTIFICATION OF OPIOID TREATMENT PROGRAMS Procedures for Review of Suspension or...

Eco-Kids to the Rescue with Help from Technology.

ERIC Educational Resources Information Center

Novelli, Joan

1994-01-01

Students can participate in worldwide environmental adventures from the classroom. The Puddles to Pondwater software program introduces students to ponds and freshwater creatures worldwide. Students can adopt team members on the Congo Expedition, a group studying the African environment, and follow the expedition via satellite data and…

IODP Expedition 354 to the Bengal Fan: a Neogene record of Himalayan erosion. Implications on the carbon cycle

NASA Astrophysics Data System (ADS)

France-Lanord, Christian; Spiess, Volkard; Galy, Albert; Galy, Valier; Huyghe, Pascale; Klaus, Adam; IODP Expedition 354 Scientists

2016-04-01

Bengal Fan Expedition 354 drilled an E-W transect in the middle fan at 8°N to investigate interactions between the growth of the Himalaya, the development of the Indian monsoon, and processes affecting the carbon cycle. A comprehensive record of turbiditic deposition between the Late Oligocene and Holocene was drilled over a seven sites E-W transect at 8°N. Shipboard results reveal that the chemical and mineralogical compositions of turbiditic sediments cored across the transect are relatively stable throughout the Neogene. By comparison to modern river sediment compositions (Lupker et al. ref), they reveal a weak intensity of chemical weathering without marked variation through time. Clay assemblages are dominated by illite and chlorite with minor proportions of newly formed clays. This differs from the distal fan record (Leg 116) where the Late Miocene and Pliocene turbidites show high weathering signatures and smectite rich clay assemblage. This difference im plies that the distal fan record does not reflect to an evolution of the source erosion. Rather it is controlled by a change in sediment transport within the fan. Shipboard estimates of organic carbon loading and behaviour resemble observations made in the modern Ganga-Brahmaputra river sediments, suggesting efficient terrestrial organic carbon burial in the Bengal Fan [1]. Preliminary observations support the idea that Himalayan erosion has consumed atmospheric CO2 through the burial of organic carbon, more than by silicate weathering. The main evolution observed in Expedition 354 record is the content of detrital carbonate that is persistent through the Neogene but appears to show a consistent decreasing trend from 8-10% during the Miocene to 3-6% during the Pleistocene and Pliocene. Also, a prominent feature of Miocene silt and sand beds is the higher abundance of plant fragments compared to younger sediments. Together these observations reveal changes in the sediment sources and erosion conditions of the hinterland during the Miocene and Pliocene. Amongst hypotheses, the Miocene Himalaya may have exposed more Tethyan limestone rich formations than during Pliocene to modern time. Alternatively, carbonate preservation during erosion may reflect lower water/sediment ratio, which would imply weaker weathering condition during Miocene. Expedition 354 cores will allow to estimate the overall impact of Himalayan erosion on the carbon cycle by coupling growth rate of the fan, erosion rate and chemical composition of the sediment. Preliminary observations support the idea that Himalayan erosion has consumed atmospheric CO2 through the burial of organic carbon, more than by silicate weathering. Ref: http://dx.doi.org/10.1016/j.epsl.2013.01.038

AURORA BOREALIS: a polar-dedicated European Research Platform

NASA Astrophysics Data System (ADS)

Wolff-Boenisch, Bonnie; Egerton, Paul; Thiede, Joern; Roberto, Azzolini; Lembke-Jene, Lester

2010-05-01

Polar research and in particular the properties of northern and southern high latitude oceans are currently a subject of intense scientific debate and investigations, because they are subject to rapid and dramatic climatic variations. Polar regions react more rapidly and intensively to global change than other regions of the earth. A shrinking of the Arctic sea-ice cover, potentially leading to an opening of sea passages to the north of North America and Eurasia, on the long to a "blue" Arctic Ocean would additionally have a strong impact on transport, commerce and tourism bearing potential risk for humans and complex ecosystems in the future. In spite of their critical role processes and feedbacks, especially in winter but not exclusively, are virtually unknown: The Arctic Ocean for example, it is the only basin of the world's oceans that has essentially not been sampled by the drill ships of the Deep-Sea Drilling Project (DSDP) or the Ocean Drilling Program (ODP) and its long-term environmental history and tectonic structure is therefore poorly known. Exceptions are the ODP Leg 151 and the more recent very successful ACEX-expedition of the Integrated Ocean Drilling Program (IODP) in 2004. To help to address the most pressing questions regarding climate change and related processes, a Pan-European initiative in the field of Earth system science has been put in place: AURORA BOREALIS is the largest environmental research infrastructure on the ESFRI roadmap of the European Community. AURORA BOREALIS is a very powerful research icebreaker, which will enable year-round operations in the Arctic and the Antarctic as well as in the adjacent ocean basins. Equipped with its drilling rig, the vessel is also capable to explore the presently completely unknown Arctic deep-sea floor. Last but not least, the ship is a floating observatory and mobile monitoring platform that permits to measure on a long-term basis comprehensive time series in all research fields relevant to global climate change. Chances and challenges rest in securing the construction and operation costs that need a dedicated consortium of interested countries and institutions to help tackling the biggest challenges of the next decades.

IODP-ICDP Expedition 364: Drilling the Chicxulub impact crater to understand planetary evolution and mass extinction

NASA Astrophysics Data System (ADS)

Gulick, S. P. S.; Morgan, J. V.

2017-12-01

The most recent of Earth's five largest mass extinction events occurred 66 Ma, coeval with the impact of a 12 km asteroid, striking at 60 degrees into what is today the Yucatán Peninsula, México, producing the 200 km-wide Chicxulub crater. This impact, by some estimations, drove the extinction of 75% of life on Earth at the genus level. The mass extinction event marks the boundary between the Cretaceous and Paleogene. Proposed kill mechanisms include thermal effects caused by the reentry of fast ejecta into Earth's atmosphere, dust and sulfate aerosols reducing Earth's solar insolation, ocean acidification, and metal toxicity due to the chemical make-up of the impactor. The magnitude and duration of these processes is still debated, and further evaluation of the proposed kill mechanisms requires an understanding of the mechanics of the Chicxulub impact as well as the resulting global environmental perturbations. In April and May 2016, the International Ocean Discovery Program, with co-funding from the International Continental Scientific Drilling Program, successfully cored into the Chicxulub impact crater with nearly 100% recovery. These cores include the first-ever samples of the transition from an intact peak ring through post-impact sediments. A peak ring is a discontinuous ring of mountains observed within the central basin of all large impact craters on rocky planets. Newly drilled cores include the uplifted target rocks, melt-rich impactites, hydrothermal deposits, a possible settling layer, and the resumption of carbonate sedimentation. The discovery that Chicxulub's peak ring consists of largely granitic crust uplifted by 10 km calibrates impact models and allows for observation of impact processes. At the top of the peak ring, the K-Pg boundary deposit includes a impactite sequence 130 m thick deposited by processes that range from minutes to likely years post-impact. This sequence is then overprinted by hydrothermal processes that lasted at least 100s Kyr post-impact and may have fed a subsurface ecosystem within the crater. The full recovery of life within the crater spans from immediately after impact through millions years allowing for a first-order assessment of the environmental consequences of the impact ("kill mechanisms").

Can ship-to-classroom interactions aid in teaching state-mandated curricula to special needs students?

NASA Astrophysics Data System (ADS)

Haddad, A.; Turner, M.; Samuelson, L.; Scientific Team of IODP Expedition 336: Mid-Atlantic Ridge Microbiology

2011-12-01

Cutting edge science is so exciting to elementary-level students with special needs that they are constantly asking for more! We drew on this enthusiasm and developed an interaction between special needs students and scientists performing cutting edge research on and below the ocean floor with the goal of teaching them state-mandated curricula. While on board the JOIDES Resolution during IODP Expedition 336: Mid-Atlantic Ridge Microbiology (Fall 2011), scientists interacted with several special needs classrooms in the Phoenix, Arizona metro area via weekly activities, blogs, question-and-answer sessions and Skype calls revolving around ocean exploration. All interactions were developed to address Arizona Department of Education curriculum standards in reading, writing, math and science and tailored to the learning needs of the students. Since the usual modalities of teaching (lecturing, Powerpoint presentations, independent reading) are ineffective in teaching students with special needs, we employed as much hands-on, active student participation as possible. The interactions were also easily adaptable to include every student regardless of the nature of their special needs. The effectiveness of these interactions in teaching mandated standards was evaluated using pre- and post-assessments and are presented here. Our goal is to demonstrate that special needs students benefit from being exposed to real-time science applications.

Dynamic Passage of Topography Beneath the Southern Costa Rica Forearc seen with Seismic Stratigraphy

NASA Astrophysics Data System (ADS)

Edwards, J. H.; Kluesner, J. W.; Silver, E. A.

2014-12-01

3D seismic reflection data (CRISP) collected across the southern Costa Rica margin reveals that a thick, deforming sedimentary wedge underlies the younger slope sediments (Silver et al., this meeting). The older wedge material and younger slope sediments are separated by a high-amplitude regional unconformity. Seismic stratigraphy of the sedimentary strata overlying this regional unconformity reflects a dynamic deformation history of the margin. The younger slope sediments contain series of more localized unconformities, separating sedimentary units as thick as 1 km that reveal a dynamically changing set of inverted, overlapping basins. The geometry of these overlapping, inverted basins indicate sequential uplift events. The direction of basin thickening varies upsection, and these basins are cut by both thrust and normal faults and are deformed by folding. Structural development appears to be controlled by relief on the subducting plate interface, which induces uplift and subsidence and thereby controls the pattern of erosion and deposition. We interpret the evolution of these inverted stratigraphic packages as forming from subducting topography. Correlating these seismic-stratigraphic packages to recent drilling based on preliminary magnetostratigraphy from IODP site U1413 (Expedition 344 Scientists, 2013), allows us to date the passage of the subducting plate topography beginning ~2 Ma.

New evidence of Hawaiian coral reef drowning in response to meltwater pulse-1A

NASA Astrophysics Data System (ADS)

Sanborn, Kelsey L.; Webster, Jody M.; Yokoyama, Yusuke; Dutton, Andrea; Braga, Juan C.; Clague, David A.; Paduan, Jennifer B.; Wagner, Daniel; Rooney, John J.; Hansen, John R.

2017-11-01

Fossil coral reefs are valuable recorders of glacio-eustatic sea-level changes, as they provide key temporal information on deglacial meltwater pulses (MWPs). The timing, rate, magnitude, and meltwater source of these sea-level episodes remain controversial, despite their importance for understanding ocean-ice sheet dynamics during periods of abrupt climatic change. This study revisits the west coast of the Big Island of Hawaii to investigate the timing of the -150 m H1d terrace drowning off Kawaihae in response to MWP-1A. We present eight new calibrated 14C-AMS ages, which constrain the timing of terrace drowning to at or after 14.75 + 0.33/-0.42 kyr BP, coeval with the age of reef drowning at Kealakekua Bay (U-Th age 14.72 ± 0.10 kyr BP), 70 kms south along the west coast. Integrating the chronology with high-resolution bathymetry and backscatter data, detailed sedimentological analysis, and paleoenvironmental interpretation, we conclude the H1d terrace drowned at the same time along the west coast of Hawaii in response to MWP-1A. The timing of H1d reef drowning is within the reported uncertainty of the timing of MWP-1A interpreted from the IODP Expedition 310 Tahitian reef record.

Overview of the evolution of clay mineralogy in the Gulf of Mexico: implications for regional climate and drainage history of the Mississippi and Brazos-Trinity Rivers

NASA Astrophysics Data System (ADS)

Adatte, T.; John, C. M.; Flemings, P. B.; Behrmann, J.

2005-12-01

In this paper we present the overview and preliminary results of the analysis of clay minerals in two mini basins drilled during IODP Expedition 308. The goal of our project is to explore the vertical and temporal trends in clay mineralogy in the Ursa Basin and the Brazos-Trinity basin #4. The Brazos-Trinity basin was the sink for sands and clays carried by the Brazos and Trinity Rivers, while the Ursa basin was the sink for sediments carried by the Mississippi river. Reconstructing clay minerals (phyllosilicates <2μm in size) accumulations at these locations could thus potentially yield information on changes in the transport and the source of the siliclastic material transported in the course of the Pleistocene by these three rivers. Moreover, because the type of clay formed in soils through weathering processes largely depend on temperature and amount of precipitation, the dataset generated could provide clues on past climate changes. Some of the mechanisms that are hypothesized to play a major role in controlling clay accumulation in the basins investigated are reworking of clays on the American continent (controlled at the time-scale investigated here by changes in precipitation) and turbidity current deposition (controlled mainly by sea-level changes and thus glacio-eustasy). Finally, a major focusing point of Expedition 308 was sediment physical properties in an overpressured basin. Because each clay mineral specie has a specific average grain sizes, physical properties and cation exchange capacity, the clay mineral composition of the sediment investigated here (dominated by clay-sized particles) may partly control how these sediments react to changes in pressure and temperature. Thus, clay mineral data could contribute to our understanding of the physical properties of the sediments in overpressured basins, and collaborations with geotechnical scientist are planned.

JEODI Workshop: Arctic site survey challenges

NASA Astrophysics Data System (ADS)

Jokat, W.; Backman, J.; Kristoffersen, Y.; Mikkelsen, N.; Thiede, J.

2003-04-01

In past decades the geoscientific activities in the High Arctic were rather low compared to other areas on the globe. The remoteness of the region and the difficult logistical conditions made Arctic research very expensive and the results unpredictable. In the late 80's this situation changed to the better since modern research icebreaker became available to the scientific community. These research platforms provided opportunities in terms of equipment, which was standard in other regions. Where necessary techniques were adapted allowing to conduct the experiments even in difficult ice conditions, e.g. multi-channel seismic. In the last decade the Arctic Ocean were identified to play a key role in our understanding of the Earth's climate. An urgent need for scientific deep drill holes in the central Arctic was obvious to better understand the climate evolution of the past in a regional and global sense. However, to select and prepare the drilling experiments sufficient site survey data, especially seismic data, are needed. These problems were addressed during a recent JEODI workshop in Copenhagen. The participants recommended dedicated expeditions tothe Alpha-Mendeleev Ridge, the Lomonosov Ridge and the Gakkel Ridge to provide a critical amount of geophysical data for future drilling efforts. An international expedition to the Alpha-Mendeleev Ridge was proposed as part of the International Geophysical Polar Year 2006/07 to investigate the least known oceanic ridge of the world's ocean. Besides scientific targets in the High Arctic it became obvious during the workshop that in the marginal seas and plateaux sufficient geophysical data exist to submit drilling proposals like for the Yermak Plateau, the Chukchi Plateau/Northwind Ridge and Laptew Sea continental margin. These proposals would perfectly complement the highly ranked drilling proposal on Lomonosov Ridge, which hopefully can be drilled in 2004 within the ODP/IODP programme. This presentation will provide information on the major results of this workshop as well as the planned activities in the next decade.

Structural characteristics of the décollement zone and underthrust sediments in the Nankai accretionary prism: Geologic architectures in the Site C0023, IODP Expedition 370

NASA Astrophysics Data System (ADS)

Yamamoto, Y.; Okutsu, N.; Yamada, Y.; Bowden, S.; Tonai, S.; Yang, K.; Tsang, M. Y.; Hirose, T.; Kamiya, N.

2017-12-01

Expedition 370 penetrated the accretionary prism, plate boundary décollement zone, and underthrust sediment and touched the basement basalt on the Philippine Sea Plate. The drilling site (C0023) is located 4 km NE from the legacy sites, Sites 808 and 1174. Compared to the legacy sites, the décollement zone is characterized by weak and intermittent negative reflectors in the seismic profile. Onboard physical properties, e.g. porosity and P-wave velocity data, indeed show the smaller gaps at the top of the décollement zone. The nature of the deformation along the décollement zone represented 40 m thick phacoidal deformation zone composed of fragmented mudstone with slickenlines on the surfaces in the Sites 808 and 1174. Compare with this, décollement zone in Site C0023 represented the weaker and non-localized deformation zone comprised of alternating zone of 1 m thick phacoidal deformation zones and a few 10 m of intact intervals in the Site C0023. Many normal faults striking parallel to the trench were identified just below the décollement zone, which is indicative of non-localized deformations along the décollement zone. Many of these faults were accompanied with calcite and sulphate mineral veins (anhydrite and barite), indicative of high-temperature fluid migration just above the ridge-spreading center. Based on the paleomagnetic restoration of structure to the geologic coordinate, attitudes of the bedding and fault planes in the Site C0023 are controlled by two factors: 1) subduction/accretion producing the trench-parallel bedding strikes and trench-perpendicular principal stress and 2) ridge spreading that produces ridge-parallel bedding and vein strikes. The former developed in the accretionary prism and the upper part of the underthrust sediment (<900 mbsf), whereas the latter occurs in the lower part (>900 mbsf). These tectonic variations might affect fluid migration pathways.

The Paleocene Eocene carbon isotope excursion in higher plant organic matter: Differential fractionation of angiosperms and conifers in the Arctic

NASA Astrophysics Data System (ADS)

Schouten, Stefan; Woltering, Martijn; Rijpstra, W. Irene C.; Sluijs, Appy; Brinkhuis, Henk; Sinninghe Damsté, Jaap S.

2007-06-01

A study of upper Paleocene-lower Eocene (P-E) sediments deposited on the Lomonosov Ridge in the central Arctic Ocean reveals relatively high abundances of terrestrial biomarkers. These include dehydroabietane and simonellite derived from conifers (gymnosperms) and a tetra-aromatic triterpenoid derived from angiosperms. The relative percentage of the angiosperm biomarker of the summed angiosperm + conifer biomarkers was increased at the end of the Paleocene-Eocene thermal maximum (PETM), different when observed with pollen counts which showed a relative decrease in angiosperm pollen. Stable carbon isotopic analysis of these biomarkers shows that the negative carbon isotope excursion (CIE) during the PETM amounts to 3‰ for both conifer biomarkers, dehydroabietane and simonellite, comparable to the magnitude of the CIE inferred from marine carbonates, but significantly lower than the 4.5‰ of the terrestrial C 29n-alkane [M. Pagani, N. Pedentchouk, M. Huber, A. Sluijs, S. Schouten, H. Brinkhuis, J.S. Sinninghe Damsté, G.R. Dickens, and the IODP Expedition 302 Expedition Scientists (2006), Arctic's hydrology during global warming at the Paleocene-Eocene thermal maximum. Nature, 442, 671-675.], which is a compound sourced by both conifers and angiosperms. Conspicuously, the angiosperm-sourced aromatic triterpane shows a much larger CIE of 6‰ and suggests that angiosperms increased in their carbon isotopic fractionation during the PETM. Our results thus indicate that the 4.5‰ C 29n-alkane CIE reported previously represents the average CIE of conifers and angiosperms at this site and suggest that the large and variable CIE observed in terrestrial records may be partly explained by the variable contributions of conifers and angiosperms. The differential response in isotopic fractionation of angiosperms and conifers points to different physiological responses of these vegetation types to the rise in temperature, humidity, and greenhouse gases during the PETM.

Runaways: Some Suggestions for Prevention, Coordinating Services, and Expediting the Reentry Process.

ERIC Educational Resources Information Center

Rohr, Michael E.; James, Richard

1994-01-01

Examines how school counselors can assist runaways. The authors focus on prevention, runaway programs, and how to expedite school reentry. Because school counselors invariably spend time with runaways, counselors can become more effective and efficient both in the short and long term in helping these troubled clients. (RJM)

Expedition 54 Soyuz Docking

NASA Image and Video Library

2017-12-19

NASA International Space Station Program Manager Kirk Shireman speaks with the Expedition 54 crew from the Moscow Mission Control Center in Korolev, Russia a few hours after the Soyuz MS-07 docked to the International Space Station on Tuesday, Dec. 19, 2017. Hatches were opened at 5:55 a.m. EST and Anton Shkaplerov of Roscosmos, Scott Tingle of NASA, and Norishige Kanai of the Japan Aerospace Exploration Agency (JAXA) joined Expedition 54 Commander Alexander Misurkin of Roscosmos and crewmates Mark Vande Hei and Joe Acaba of NASA aboard the orbiting laboratory. Photo Credit: (NASA/Joel Kowsky)

Extreme diagenesis displayed by Pliocene-Pleistocene Calcareous Nannofossils in IODP Hole 1396A, adjacent to Montserrat Island in the Lesser Antilles

NASA Astrophysics Data System (ADS)

Aljahdali, M. H.; Behzad, A.; Missimer, T. M.; Wise, S. W.; Scientists, E.

2013-12-01

Adjacent to Montserrat Island in the Lesser Antilles of the Caribbean Sea, Integrated Ocean Drilling Program (IODP) Site 1396 recovered lower Pliocene to Pleistocene calcareous nannofossil assemblages (CN11 to CN15) that range between common to abundant and display a variety of preservations. High-resolution Scanning Electron Microscopy (SEM) observation of calcareous nannofossil assemblages in selected samples from Hole 1396A, shows severe diagenesis (overgrowth and/or dissolution) even near the top of the sequence. The nannofossil assemblages in this relatively shallow basin (e.g., 800 m) reveal abnormal diagenesis for such young specimens that are quite similar to the heavy overgrowths and dissolution generally seen only in older deposits (e.g., Cretaceous). Our hypothesis is that volcanic activity in the region probably induced this extreme diagenesis. A more detailed examination of these samples should provide a better understanding of the progression of carbonate diagenesis in this basin. The nannofossil biostratigraphy and magnetostratigraphy at Site 1396 also suggest lower sedimentation rates in the Pleistocene than in the Pliocene. A comparison site (ODP Leg 165 Site 1000) in the Caribbean Sea also shows a similar sedimentation-rate pattern. This we interpret as a regional event caused by the closure of the Central American Seaway.

Next Generation Science Partnerships

NASA Astrophysics Data System (ADS)

Magnusson, J.

2016-02-01

I will provide an overview of the Next Generation Science Standards (NGSS) and demonstrate how scientists and educators can use these standards to strengthen and enhance their collaborations. The NGSS are rich in content and practice and provide all students with an internationally-benchmarked science education. Using these state-led standards to guide outreach efforts can help develop and sustain effective and mutually beneficial teacher-researcher partnerships. Aligning outreach with the three dimensions of the standards can help make research relevant for target audiences by intentionally addressing the science practices, cross-cutting concepts, and disciplinary core ideas of the K-12 science curriculum that drives instruction and assessment. Collaborations between researchers and educators that are based on this science framework are more sustainable because they address the needs of both scientists and educators. Educators are better able to utilize science content that aligns with their curriculum. Scientists who learn about the NGSS can better understand the frameworks under which educators work, which can lead to more extensive and focused outreach with teachers as partners. Based on this model, the International Ocean Discovery Program (IODP) develops its education materials in conjunction with scientists and educators to produce accurate, standards-aligned activities and curriculum-based interactions with researchers. I will highlight examples of IODP's current, successful teacher-researcher collaborations that are intentionally aligned with the NGSS.

Stratigraphic calibration of Oligocene-Miocene organic-walled dinoflagellate cysts from offshore Wilkes Land, East Antarctica, and a zonation proposal

NASA Astrophysics Data System (ADS)

Bijl, Peter K.; Houben, Alexander J. P.; Bruls, Anja; Pross, Jörg; Sangiorgi, Francesca

2018-01-01

There is growing interest in the scientific community in reconstructing the paleoceanography of the Southern Ocean during the Oligocene-Miocene because these time intervals experienced atmospheric CO2 concentrations with relevance to our future. However, it has remained notoriously difficult to put the sedimentary archives used in these efforts into a temporal framework. This is at least partially due to the fact that the bio-events recorded in organic-walled dinoflagellate cysts (dinocysts), which often represent the only microfossil group preserved, have not yet been calibrated to the international timescale. Here we present dinocyst ranges from Oligocene-Miocene sediments drilled offshore the Wilkes Land continental margin, East Antarctica (Integrated Ocean Drilling Program (IODP) Hole U1356A). In addition, we apply statistical means to test a priori assumptions about whether the recorded taxa were deposited in situ or were reworked from older strata. Moreover, we describe two new dinocyst species, Selenopemphix brinkhuisii sp. nov. and Lejeunecysta adeliensis sp. nov., which are identified as important markers for regional stratigraphic analysis. Finally, we calibrate all identified dinocyst events to the international timescale using independent age control from calcareous nanoplankton and magnetostratigraphy from IODP Hole U1356A, and we propose a provisional dinoflagellate cyst zonation scheme for the Oligocene-Miocene of the Southern Ocean.

The Himalaya-Bengal Fan source to sink system - new insights by correlation of re-processed seismic data and IODP Expedition 354 results

NASA Astrophysics Data System (ADS)

Bergmann, Fenna; Schwenk, Tilmann; Spiess, Volkard; France-Lanord, Christian

2016-04-01

The Bengal Fan, hosted in the northern Indian Ocean, is the largest submarine fan on Earth. Fan evolution started in the Early Eocene as a direct response to the collision of India with the Asian continent in Middle Paleocene times. Subsequently the Himalayan plateau uplift was initiated. Thereby generated interactions with the regional climate caused the evolution of the Indian monsoonal system. Drained by the rivers Ganges and Brahmaputra, ~ 80% of eroded Himalayan sediments are deposited in the Bengal Fan. Hence, the Fan provides the most complete record of the Himalayan history and is well suited to investigate the direct link between the tectonic uplift and the climate evolution of the region. Sediments are transported onto the deep sea fan by turbidity currents building up chan-nel-levee systems. These channel-levee systems are the main architectural elements of the Bengal Fan and are suspected to have their onset in Late Miocene times. Frequent channel avulsion on the upper fan led to the abandonment of old channels and formation of new channel-levee systems or even channel-reoccupation. This complex erosional/depositional system involves lateral depocenter migration, probably on millennial timescales. Conse-quently, investigations of the Himalaya as sediment source begins with a comprehensive understanding of transport, deposition and modification within the Bengal Fan sediment sink. In February/March 2015 the IODP Expedition 354 drilled at 7 sites along a ~320 km long E-W transect at 8° N. Aiming at the recovery of pre-fan deposits and deposits of the Pliocene and Upper Miocene Fan evolution, three deep sites (900 - 1200 mbsf) were realized. These where complemented by four shallow sites (200-300 mbsf) for a detailed study of the depos-its of the last 1-2 million years, including the latest known channel activities (Holocene times). Several channel-levee systems and inter-channel deposits were drilled, active at different times of Fan evolution. To connect the sites of the drilling transect by means of seismo-stratigraphic analysis a large seismo-acoustic dataset gathered during cruises SO93 (1994), SO125/126 (1997) and SO188 (2006), all carried out in cooperation between the University of Bremen and the BGR, Hannover, is available. The dataset contains multichannel seismic data acquired with differ-ent seismic sources (GI-Gun/Watergun) to achieve differing subbottom penetration/resolution ratios. Although most of the pre-site survey data were already processed, major improve-ment could be gained by thoroughly (re) processing using new processing techniques and software developments. First processing results show significantly enhanced S/N ratio, reso-lution and reflector coherency. Full processing of the Watergun data was conducted for the first time. This high vertical resolution data has so far never been investigated and comple-ments the database, especially for a more detailed study of the upper few hundred meters of Bengal Fan deposits. First examinations of the watergun data in combination with drilling results proved them to be beneficial for the crucial borehole - seismic correlation and the investigations of the internal levee architecture, especially for the latest active channel-levee system.

43 CFR 404.28 - Is it possible to expedite the completion of an appraisal investigation or feasibility study?

Code of Federal Regulations, 2010 CFR

2010-10-01

... served by a proposed rural water supply project has urgent and compelling water needs, Reclamation will... Regulations Relating to Public Lands BUREAU OF RECLAMATION, DEPARTMENT OF THE INTERIOR RECLAMATION RURAL WATER SUPPLY PROGRAM Overview § 404.28 Is it possible to expedite the completion of an appraisal investigation...

SUTIL: system utilities routines programmer's reference manual

NASA Technical Reports Server (NTRS)

Harper, D.

1976-01-01

A package of FORTRAN callable subroutines which allows efficient communication of data between users and programs is described. Proper utilization of the SUTIL package to reduce program core requirements and expedite program development is emphasized.

Citings on the Educational Horizon

ERIC Educational Resources Information Center

Mathies, Lorraine

1975-01-01

Article reviewed programs designed to help blind persons take advantage of information not in print form, programs which offer information on careers, programs designed to foster private sponsorship of basic research expeditions, and programs that eliminate social bias in educational materials. (Author/RK)

Expedition 54 Soyuz Docking

NASA Image and Video Library

2017-12-19

Japan Aerospace Exploration Agency (JAXA) International Space Station Program Manager Koichi Wakata speaks with the Expedition 54 crew from the Moscow Mission Control Center in Korolev, Russia a few hours after the Soyuz MS-07 docked to the International Space Station on Tuesday, Dec. 19, 2017. Hatches were opened at 5:55 a.m. EST and Anton Shkaplerov of Roscosmos, Scott Tingle of NASA, and Norishige Kanai of the Japan Aerospace Exploration Agency (JAXA) joined Expedition 54 Commander Alexander Misurkin of Roscosmos and crewmates Mark Vande Hei and Joe Acaba of NASA aboard the orbiting laboratory. Photo Credit: (NASA/Joel Kowsky)

Taxi and Expedition Three crews pose for a group photo in Zvezda during Expedition Three

NASA Image and Video Library

2001-10-23

ISS003-E-7036 (23-31 October 2001) --- Astronaut Frank L. Culbertson, Jr. (foreground), Expedition Three mission commander, and the Soyuz Taxi crewmembers assemble for a group photo in the Zvezda Service Module on the International Space Station (ISS). From the left are Flight Engineer Konstantin Kozeev, Commander Victor Afanasyev, and French Flight Engineer Claudie Haignere. Afanasyev and Kozeev represent Rosaviakosmos, and Haignere represents ESA, carrying out a flight program for CNES, the French Space Agency, under a commercial contract with the Russian Aviation and Space Agency. This image was taken with a digital still camera.

Taxi and Expedition Three crews pose for a group photo in Zvezda during Expedition Three

NASA Image and Video Library

2001-10-23

ISS003-E-7037 (23-31 October 2001) --- Astronaut Frank L. Culbertson, Jr. (foreground), Expedition Three mission commander, and the Soyuz Taxi crewmembers assemble for a group photo in the Zvezda Service Module on the International Space Station (ISS). From the left are Flight Engineer Konstantin Kozeev, Commander Victor Afanasyev, and French Flight Engineer Claudie Haignere. Afanasyev and Kozeev represent Rosaviakosmos, and Haignere represents ESA, carrying out a flight program for CNES, the French Space Agency, under a commercial contract with the Russian Aviation and Space Agency. This image was taken with a digital still camera.

The Abrupt Onset of the Modern South Asian Monsoon Winds (iodp Exp. 359)

NASA Astrophysics Data System (ADS)

Betzler, C.; Eberli, G. P.; Kroon, D.; Wright, J. D.; Swart, P. K.; Nath, B. N.; Reijmer, J.; Alvarez Zarikian, C. A.

2016-12-01

The South Asian Monson (SAM) is one of the most extreme features in Earth's climate system, yet its initiation and variations are not well established. The SAM is a seasonal reversal of winds accompanied by changes in precipitation with heavy rain during the summer monsoon. It is one of the most intense annually recurring climatic elements and of immense importance in supplying moisture to the Indian subcontinent thus affecting human population and vegetation, as well as marine biota in the surrounding seas. The seasonal precipitation change is one of the SAM elements most noticed on land, whereas the reversal of the wind regime is the dominating driver of circulation in the central and northern Indian Ocean realm. New data acquired during International Ocean Discovery Program Expedition 359 from the Inner Sea of the Maldives provide a previously unread archive that reveals an abrupt onset of the SAM-linked ocean circulation pattern and its relationship to the long term Neogene climate cooling. In particular it registers ocean current fluctuations and changes of intermediate water mass properties for the last 25 myrs that are directly related to the monsoon. Dating the deposits of SAM wind-driven currents yields an age of 12.9 Ma indicating an abrupt SAM onset, over a short period of 300 kyrs. This coincided with the Indian Ocean Oxygen Minimum Zone expansion as revealed by geochemical tracers and the onset of upwelling reflected by the sediment's content of sedimentary organic matter. A weaker `proto-monsoon' existed between 12.9 and 25 Ma, as mirrored by the sedimentary signature of dust influx. Abrupt SAM initiation favors a strong influence of climate in addition to the tectonic control, and we propose that the post Miocene Climate Optimum cooling, together with increased continentalization and establishment of the bipolar ocean circulation, i.e. the beginning of the modern world, shifted the monsoon over a threshold towards the modern system.

Persistent Identifiers for Field Deployments: A Missing Link in the Provenance Chain

NASA Astrophysics Data System (ADS)

Arko, R. A.; Ji, P.; Fils, D.; Shepherd, A.; Chandler, C. L.; Lehnert, K.

2016-12-01

Research in the geosciences is characterized by a wide range of complex and costly field deployments including oceanographic cruises, submersible dives, drilling expeditions, seismic networks, geodetic campaigns, moored arrays, aircraft flights, and satellite missions. Each deployment typically produces a mix of sensor and sample data, spanning a period from hours to decades, that ultimately yields a long tail of post-field products and publications. Publishing persistent, citable identifiers for field deployments will facilitate 1) preservation and reuse of the original field data, 2) reproducibility of the resulting publications, and 3) recognition for both the facilities that operate the platforms and the investigators who secure funding for the experiments. In the ocean domain, sharing unique identifiers for field deployments is a familiar practice. For example, the Biological and Chemical Oceanography Data Management Office (BCO-DMO) routinely links datasets to cruise identifiers published by the Rolling Deck to Repository (R2R) program. In recent years, facilities have started to publish formal/persistent identifiers, typically Digital Object Identifiers (DOIs), for field deployments including seismic networks, oceanographic cruises, and moored arrays. For example, the EarthChem Library (ECL) publishes a DOI for each dataset which, if it derived from an oceanographic research cruise on a US vessel, is linked to a DOI for the cruise published by R2R. Work is underway to create similar links for the IODP JOIDES Resolution Science Operator (JRSO) and the Continental Scientific Drilling Coordination Office (CSDCO). We present results and lessons learned including a draft schema for publishing field deployments as DataCite DOI records; current practice for linking these DOIs with related identifiers such as Open Researcher and Contributor IDs (ORCIDs), Open Funder Registry (OFR) codes, and International Geo Sample Numbers (IGSNs); and consideration of other identifier types for field deployments such as UUIDs and Handles.

Occurrence of Quaternary turbidite deposits in the central South China Sea: Response to global sea-level changes

NASA Astrophysics Data System (ADS)

Liu, Z.; Zhang, X.; Christophe, C.; Peleo-Alampay, A.; Guballa, J. D. S.; Li, P.; Liu, C.

2016-12-01

Terrigenous turbidite layers frequently occur at the upper 150-m-thick sedimentary sequence of Hole U1431D (15º22.54'N, 117 º00.00'E, 4240.5 m water depth), International Ocean Discovery Program (IODP) Expedition 349, near the relict spreading ridge in the central South China Sea. This study implies visual statistics combined with grain size, clay mineralogy, and Nd-Sr isotope analyses to reconstruct the occurrence of these turbidite layers. The age-model of combined calcareous nannofossils, planktonic foraminifers, and paleomagnetism suggests that the sedimentary sequence spans the entire Quaternary with an age of 2.6 Ma at the depth of 150 mcd below the seafloor. Our results show that the turbidite deposits are dominated by silt with sandy silt and silty clay, poorly sorted, and grading upward with erosion base. The occurrence of turbidite layers are highly frequent with about 3.06 layers per meter and an average thickness of 14.64 cm per layer above 96 mcd ( 1.6 Ma), while the lower part turbudite layers are less frequently developed with 1.16 layers per meter and an average thickness of 5.67 cm. Provenance analysis indicates that Taiwan, about 900 km northward to the studied site, is the major source for these terrigenous sediments, implying the long run-out turbidity current activity over the very low-gradient deep-sea plain of the South China Sea. The frequency of the turbidite layer occurrence is well correlated to the Quaternary global sea-level change history, with the high frequency occurred during the lower sea-level stands. Our study suggests that the glacial-interglacial-scale sea-level change has controlled terrigenous sediment input from Taiwan and the northern shelf of the South China Sea during the Quaternary. The increase of turbidite layer frequency since 1.6 Ma in the central South China Sea could be triggered by the enlarged amplitude of sea-level change.

Deep subsurface life in Bengal Fan sediments (IODP Exp. 354)

NASA Astrophysics Data System (ADS)

Adhikari, R. R.; Heuer, V. B.; Elvert, M.; Kallmeyer, J.; Kitte, J. A.; Wörmer, L.; Hinrichs, K. U.

2017-12-01

We collected Bengal Fan sediment samples along a 8°N transect during International Ocean Discovery Program Expedition 354 (February - March 2015, Singapore - Colombo, Sri Lanka) to study subseafloor life in this, as yet unstudied, area. Among other biogeochemical parameters, we quantified microbial biomass by analyzing prokaryotic cells using epifluorescence microscopy after detaching cells from the sediment, and bacterial endospores by analyzing the diagnostic biomarker dipicolinic acid (DPA) by detection of fluorescence of the terbium-DPA complex. To gain understanding of total microbial activity, we quantified hydrogen utilization potential of hydrogenase enzymes, which are ubiquitous in subsurface microorganisms, by using a tritium assay. We measured highest cell concentrations of ca. 108 cells g-1 in shallow sediments close to the seafloor. These concentrations are one to two orders of magnitude lower than in most marine continental margin settings [1]. Similar to the global trend [1], cell concentrations decreased with depth according to a power-law function. Endospore concentrations scattered between ca. 105 and 107 cells g-1 sediment at all sites and depths. We could not observe a clear relationship of endospore concentration and sediment depth; instead, it appears to be linked to lithology and total organic carbon content. Bulk Hydrogenase enzyme activity ranged from nmolar to μmolar range of H2 g-1d-1. Similar to previous observations [2], per-cell hydrogen utilization depends on vertical biogeochemical zones, which could be due to the differences in hydrogen utilization requirements/efficiency of the respective metabolic processes such as sulfate reduction, methanogenesis, fermentation etc. Bengal fan is highly dynamic due to channel and levee systems and the sediments are dominated by turbidites, thick sand layers and hemipelagic deposits, which may control biogeochemical zonation. Based on our microbial biomass and activity data, we suggest that the nature, quality and origin of sedimentary material influence the deep subsurface life. [1] Kallmeyer et al., (2012) PNAS 109(40), 16213-16216 [2] Adhikari et al., (2016) Frontiers in Microbiology 7:8

"Complexity" in Polarity Transitions at the Matuyama-Brunhes Boundary and top Jaramillo in North Atlantic Deep-sea Sediments

NASA Astrophysics Data System (ADS)

Channell, J. E. T.

2016-12-01

Integrated Ocean Drilling Program (IODP) Expedition 303 to the North Atlantic provided 16 records of the Matuyama-Brunhes polarity transition (MBT) and the top Jaramillo transition, based on u-channel and discrete samples, from holes drilled at three sites (Sites U1304, U1305 and U1306) that have mean Brunhes sedimentation rates of 16-18 cm/kyr. The MBT occurs during the transition from marine isotope stage (MIS) 19.3 to MIS 18.4, with mid-point at 773 ka, and a transition duration of 5-8 kyr. The top Jaramillo occurs during MIS 28 at 992 ka with a similar 5 kyr transition duration. Combining the new records with previously published North Atlantic records (ODP Sites 983, 984 and 1063) yields a total of 24 high sedimentation rate records. The MBT yields a repetitive pattern of transitional field states as virtual geomagnetic poles (VGPs) move from high southern latitudes to loop over the Pacific, cluster in NE Asia, and transit into the mid-latitude South Atlantic before reaching high latitudes in the Northern Hemisphere. The VGPs for the top Jaramillo transition feature a loop over the Pacific, then occupation of the NE Asia cluster before transit over the Indian Ocean to high southerly latitudes. The North Atlantic MBT records described here are very different to the longitudinally constrained North Atlantic VGP paths from MBT records that are the basis for a 2007 Bayesian inversion of the MBT field. We conclude that the relatively low sedimentation rate ( 4 cm/kyr) records utilized in the Bayesian inversion have been heavily smoothed by the remanence acquisition process, and do not adequately represent the MBT field. The VGPs at the MBT and top Jaramillo, as measured in the North Atlantic, have similarities with excursion (Iceland Basin) VGP paths, and are apparently guided by maxima in downward vertical flux in the modern non-dipole (ND) field, implying longevity in ND features through time.

The effect of diagenesis and fluid migration on rare earth element distribution in pore fluids of the northern Cascadia accretionary margin

USGS Publications Warehouse

Kim, Ji-Hoon; Torres, Marta E.; Haley, Brian A.; Kastner, Miriam; Pohlman, John W.; Riedel, Michael; Lee, Young-Joo

2012-01-01

Analytical challenges in obtaining high quality measurements of rare earth elements (REEs) from small pore fluid volumes have limited the application of REEs as deep fluid geochemical tracers. Using a recently developed analytical technique, we analyzed REEs from pore fluids collected from Sites U1325 and U1329, drilled on the northern Cascadia margin during the Integrated Ocean Drilling Program (IODP) Expedition 311, to investigate the REE behavior during diagenesis and their utility as tracers of deep fluid migration. These sites were selected because they represent contrasting settings on an accretionary margin: a ponded basin at the toe of the margin, and the landward Tofino Basin near the shelf's edge. REE concentrations of pore fluid in the methanogenic zone at Sites U1325 and U1329 correlate positively with concentrations of dissolved organic carbon (DOC) and alkalinity. Fractionations across the REE series are driven by preferential complexation of the heavy REEs. Simultaneous enrichment of diagenetic indicators (DOC and alkalinity) and of REEs (in particular the heavy elements Ho to Lu), suggests that the heavy REEs are released during particulate organic carbon (POC) degradation and are subsequently chelated by DOC. REE concentrations are greater at Site U1325, a site where shorter residence times of POC in sulfate-bearing redox zones may enhance REE burial efficiency within sulfidic and methanogenic sediment zones where REE release ensues. Cross-plots of La concentrations versus Cl, Li and Sr delineate a distinct field for the deep fluids (z > 75 mbsf) at Site U1329, and indicate the presence of a fluid not observed at the other sites drilled on the Cascadia margin. Changes in REE patterns, the presence of a positive Eu anomaly, and other available geochemical data for this site suggest a complex hydrology and possible interaction with the igneous Crescent Terrane, located east of the drilled transect.

Size and Carbon Content of Sub-seafloor Microbial Cells at Landsort Deep, Baltic Sea

PubMed Central

Braun, Stefan; Morono, Yuki; Littmann, Sten; Kuypers, Marcel; Aslan, Hüsnü; Dong, Mingdong; Jørgensen, Bo B.; Lomstein, Bente Aa.

2016-01-01

The discovery of a microbial ecosystem in ocean sediments has evoked interest in life under extreme energy limitation and its role in global element cycling. However, fundamental parameters such as the size and the amount of biomass of sub-seafloor microbial cells are poorly constrained. Here we determined the volume and the carbon content of microbial cells from a marine sediment drill core retrieved by the Integrated Ocean Drilling Program (IODP), Expedition 347, at Landsort Deep, Baltic Sea. To determine their shape and volume, cells were separated from the sediment matrix by multi-layer density centrifugation and visualized via epifluorescence microscopy (FM) and scanning electron microscopy (SEM). Total cell-carbon was calculated from amino acid-carbon, which was analyzed by high-performance liquid chromatography (HPLC) after cells had been purified by fluorescence-activated cell sorting (FACS). The majority of microbial cells in the sediment have coccoid or slightly elongated morphology. From the sediment surface to the deepest investigated sample (~60 m below the seafloor), the cell volume of both coccoid and elongated cells decreased by an order of magnitude from ~0.05 to 0.005 μm3. The cell-specific carbon content was 19–31 fg C cell−1, which is at the lower end of previous estimates that were used for global estimates of microbial biomass. The cell-specific carbon density increased with sediment depth from about 200 to 1000 fg C μm−3, suggesting that cells decrease their water content and grow small cell sizes as adaptation to the long-term subsistence at very low energy availability in the deep biosphere. We present for the first time depth-related data on the cell volume and carbon content of sedimentary microbial cells buried down to 60 m below the seafloor. Our data enable estimates of volume- and biomass-specific cellular rates of energy metabolism in the deep biosphere and will improve global estimates of microbial biomass. PMID:27630628

Post-depositional formation of vivianite-type minerals alters sediment phosphorus records

NASA Astrophysics Data System (ADS)

Dijkstra, Nikki; Hagens, Mathilde; Egger, Matthias; Slomp, Caroline P.

2018-02-01

Phosphorus (P) concentrations in sediments are frequently used to reconstruct past environmental conditions in freshwater and marine systems, with high values thought to be indicative of a high biological productivity. Recent studies suggest that the post-depositional formation of vivianite, an iron(II)-phosphate mineral, might significantly alter trends in P with sediment depth. To assess its importance, we investigate a sediment record from the Bornholm Basin that was retrieved during the Integrated Ocean Drilling Program (IODP) Baltic Sea Paleoenvironment Expedition 347 in 2013, consisting of lake sediments overlain by brackish-marine deposits. Combining bulk sediment geochemistry with microanalysis using scanning electron microscope energy dispersive spectroscopy (SEM-EDS) and synchrotron-based X-ray absorption spectroscopy (XAS), we demonstrate that vivianite-type minerals rich in manganese and magnesium are present in the lake deposits just below the transition to the brackish-marine sediments (at 11.5 to 12 m sediment depth). In this depth interval, phosphate that diffuses down from the organic-rich, brackish-marine sediments meets porewaters rich in dissolved iron in the lake sediments, resulting in the precipitation of iron(II) phosphate. Results from a reactive transport model suggest that the peak in iron(II) phosphate originally occurred at the lake-marine transition (9 to 10 m) and moved downwards due to changes in the depth of a sulfidization front. However, its current position relative to the lake-marine transition is stable as the vivianite-type minerals and active sulfidization fronts have been spatially separated over time. Experiments in which vivianite was subjected to sulfidic conditions demonstrate that incorporation of manganese or magnesium in vivianite does not affect its susceptibility to sulfide-induced dissolution. Our work highlights that post-depositional formation of iron(II) phosphates such as vivianite has the potential to strongly alter sedimentary P records particularly in systems that are subject to environmental perturbation, such as a change in primary productivity, which can be associated with a lake-marine transition.

Eocene tectonic compression in Northern Zealandia: Magneto-biostratigraphic constraints from the sedimentary records of New Caledonia (Southwest Pacific Ocean)

NASA Astrophysics Data System (ADS)

Dallanave, E.; Agnini, C.; Pascher, K. M.; Maurizot, P.; Bachtadse, V.; Hollis, C. J.; Dickens, G. R.; Collot, J.; Sevin, B.; Strogen, D.; Monesi, E.

2017-12-01

Published seismic profiles acquired from the Tasman Sea and northern Zealandia area (southwest Pacific) point to a widespread Eocene convergent deformation of oceanic and continental crust, with reverse faults and uplift (Tectonic Event of the Cenozoic in the Tasman Area; TECTA). The TECTA is interpreted as the precursor of the Tonga-Kermadec subduction initiation. Grande Terre is the main island of the New Caledonia archipelago and the largest emergent portion of northern Norfolk Ridge (part of northern Zealandia). Eocene sedimentary records exposed in Grande Terre contain a transition from pelagic micrite to terrigenous-rich calciturbidites, marking a shift from passive margin to convergent tectonic regime. This could represent the local expression of the convergence inception observed on a regional scale. We conducted an integrated magneto-biostratigraphic study, based on calcareous nannofossil and radiolaria, of two early-middle Eocene records cropping out near Noumea (southwest Grande Terre) and Koumac (northwest Grande Terre). The natural remanent magnetization of the sediments is complicated by multiple vector components, likely related to the late Eocene obduction, but a characteristic remanent magnetization has been successfully isolated. Overall the record spans from magnetic polarity Chron C23n to C18n, i.e. from 51 to 39 Ma. In this robust magnetic polarity-based chronological frame, the pelagic micrite to terrigenous-rich calciturbidites occurred near the top of Chron C21n and is dated 46 Ma. Furthermore, the magnetic mineral assemblage within part of the calciturbidites consists of hematite associated with maghemite. This association indicates emergent land as source of the terrigenous, suggesting a considerable uplift. Because 94% of the Zealandia continent is submerged, ocean drilling is needed to gauge the full extent and timing of Eocene compressive deformation revealed by the seismic profiles acquired in the Tasman area. This is a primary aim of International Ocean Discovery Program (IODP) Expedition 371 (27th July - 26th September 2017).

Microbial Sulfate Reduction Potential in Coal-Bearing Sediments Down to ~2.5 km below the Seafloor off Shimokita Peninsula, Japan

PubMed Central

Glombitza, Clemens; Adhikari, Rishi R.; Riedinger, Natascha; Gilhooly, William P.; Hinrichs, Kai-Uwe; Inagaki, Fumio

2016-01-01

Sulfate reduction is the predominant anaerobic microbial process of organic matter mineralization in marine sediments, with recent studies revealing that sulfate reduction not only occurs in sulfate-rich sediments, but even extends to deeper, methanogenic sediments at very low background concentrations of sulfate. Using samples retrieved off the Shimokita Peninsula, Japan, during the Integrated Ocean Drilling Program (IODP) Expedition 337, we measured potential sulfate reduction rates by slurry incubations with 35S-labeled sulfate in deep methanogenic sediments between 1276.75 and 2456.75 meters below the seafloor. Potential sulfate reduction rates were generally extremely low (mostly below 0.1 pmol cm−3 d−1) but showed elevated values (up to 1.8 pmol cm−3 d−1) in a coal-bearing interval (Unit III). A measured increase in hydrogenase activity in the coal-bearing horizons coincided with this local increase in potential sulfate reduction rates. This paired enzymatic response suggests that hydrogen is a potentially important electron donor for sulfate reduction in the deep coalbed biosphere. By contrast, no stimulation of sulfate reduction rates was observed in treatments where methane was added as an electron donor. In the deep coalbeds, small amounts of sulfate might be provided by a cryptic sulfur cycle. The isotopically very heavy pyrites (δ34S = +43‰) found in this horizon is consistent with its formation via microbial sulfate reduction that has been continuously utilizing a small, increasingly 34S-enriched sulfate reservoir over geologic time scales. Although our results do not represent in-situ activity, and the sulfate reducers might only have persisted in a dormant, spore-like state, our findings show that organisms capable of sulfate reduction have survived in deep methanogenic sediments over more than 20 Ma. This highlights the ability of sulfate-reducers to persist over geological timespans even in sulfate-depleted environments. Our study moreover represents the deepest evidence of a potential for sulfate reduction in marine sediments to date. PMID:27761134

Predominance of Viable Spore-Forming Piezophilic Bacteria in High-Pressure Enrichment Cultures from ~1.5 to 2.4 km-Deep Coal-Bearing Sediments below the Ocean Floor

PubMed Central

Fang, Jiasong; Kato, Chiaki; Runko, Gabriella M.; Nogi, Yuichi; Hori, Tomoyuki; Li, Jiangtao; Morono, Yuki; Inagaki, Fumio

2017-01-01

Phylogenetically diverse microorganisms have been observed in marine subsurface sediments down to ~2.5 km below the seafloor (kmbsf). However, very little is known about the pressure-adapted and/or pressure-loving microorganisms, the so called piezophiles, in the deep subseafloor biosphere, despite that pressure directly affects microbial physiology, metabolism, and biogeochemical processes of carbon and other elements in situ. In this study, we studied taxonomic compositions of microbial communities in high-pressure incubated sediment, obtained during the Integrated Ocean Drilling Program (IODP) Expedition 337 off the Shimokita Peninsula, Japan. Analysis of 16S rRNA gene-tagged sequences showed that members of spore-forming bacteria within Firmicutes and Actinobacteria were predominantly detected in all enrichment cultures from ~1.5 to 2.4 km-deep sediment samples, followed by members of Proteobacteria, Acidobacteria, and Bacteroidetes according to the sequence frequency. To further study the physiology of the deep subseafloor sedimentary piezophilic bacteria, we isolated and characterized two bacterial strains, 19R1-5 and 29R7-12, from 1.9 and 2.4 km-deep sediment samples, respectively. The isolates were both low G+C content, gram-positive, endospore-forming and facultative anaerobic piezophilic bacteria, closely related to Virgibacillus pantothenticus and Bacillus subtilis within the phylum Firmicutes, respectively. The optimal pressure and temperature conditions for growth were 20 MPa and 42°C for strain 19R1-5, and 10 MPa and 43°C for strain 29R7-12. Bacterial (endo)spores were observed in both the enrichment and pure cultures examined, suggesting that these piezophilic members were derived from microbial communities buried in the ~20 million-year-old coal-bearing sediments after the long-term survival as spores and that the deep biosphere may host more abundant gram-positive spore-forming bacteria and their spores than hitherto recognized. PMID:28220112

Microbial Sulfate Reduction Potential in Coal-Bearing Sediments Down to ~2.5 km below the Seafloor off Shimokita Peninsula, Japan.

PubMed

Glombitza, Clemens; Adhikari, Rishi R; Riedinger, Natascha; Gilhooly, William P; Hinrichs, Kai-Uwe; Inagaki, Fumio

2016-01-01

Sulfate reduction is the predominant anaerobic microbial process of organic matter mineralization in marine sediments, with recent studies revealing that sulfate reduction not only occurs in sulfate-rich sediments, but even extends to deeper, methanogenic sediments at very low background concentrations of sulfate. Using samples retrieved off the Shimokita Peninsula, Japan, during the Integrated Ocean Drilling Program (IODP) Expedition 337, we measured potential sulfate reduction rates by slurry incubations with 35 S-labeled sulfate in deep methanogenic sediments between 1276.75 and 2456.75 meters below the seafloor. Potential sulfate reduction rates were generally extremely low (mostly below 0.1 pmol cm -3 d -1 ) but showed elevated values (up to 1.8 pmol cm -3 d -1 ) in a coal-bearing interval (Unit III). A measured increase in hydrogenase activity in the coal-bearing horizons coincided with this local increase in potential sulfate reduction rates. This paired enzymatic response suggests that hydrogen is a potentially important electron donor for sulfate reduction in the deep coalbed biosphere. By contrast, no stimulation of sulfate reduction rates was observed in treatments where methane was added as an electron donor. In the deep coalbeds, small amounts of sulfate might be provided by a cryptic sulfur cycle. The isotopically very heavy pyrites (δ 34 S = +43‰) found in this horizon is consistent with its formation via microbial sulfate reduction that has been continuously utilizing a small, increasingly 34 S-enriched sulfate reservoir over geologic time scales. Although our results do not represent in-situ activity, and the sulfate reducers might only have persisted in a dormant, spore-like state, our findings show that organisms capable of sulfate reduction have survived in deep methanogenic sediments over more than 20 Ma. This highlights the ability of sulfate-reducers to persist over geological timespans even in sulfate-depleted environments. Our study moreover represents the deepest evidence of a potential for sulfate reduction in marine sediments to date.

Predominance of Viable Spore-Forming Piezophilic Bacteria in High-Pressure Enrichment Cultures from ~1.5 to 2.4 km-Deep Coal-Bearing Sediments below the Ocean Floor.

PubMed

Fang, Jiasong; Kato, Chiaki; Runko, Gabriella M; Nogi, Yuichi; Hori, Tomoyuki; Li, Jiangtao; Morono, Yuki; Inagaki, Fumio

2017-01-01

Phylogenetically diverse microorganisms have been observed in marine subsurface sediments down to ~2.5 km below the seafloor (kmbsf). However, very little is known about the pressure-adapted and/or pressure-loving microorganisms, the so called piezophiles, in the deep subseafloor biosphere, despite that pressure directly affects microbial physiology, metabolism, and biogeochemical processes of carbon and other elements in situ . In this study, we studied taxonomic compositions of microbial communities in high-pressure incubated sediment, obtained during the Integrated Ocean Drilling Program (IODP) Expedition 337 off the Shimokita Peninsula, Japan. Analysis of 16S rRNA gene-tagged sequences showed that members of spore-forming bacteria within Firmicutes and Actinobacteria were predominantly detected in all enrichment cultures from ~1.5 to 2.4 km-deep sediment samples, followed by members of Proteobacteria, Acidobacteria, and Bacteroidetes according to the sequence frequency. To further study the physiology of the deep subseafloor sedimentary piezophilic bacteria, we isolated and characterized two bacterial strains, 19R1-5 and 29R7-12, from 1.9 and 2.4 km-deep sediment samples, respectively. The isolates were both low G+C content, gram-positive, endospore-forming and facultative anaerobic piezophilic bacteria, closely related to Virgibacillus pantothenticus and Bacillus subtilis within the phylum Firmicutes, respectively. The optimal pressure and temperature conditions for growth were 20 MPa and 42°C for strain 19R1-5, and 10 MPa and 43°C for strain 29R7-12. Bacterial (endo)spores were observed in both the enrichment and pure cultures examined, suggesting that these piezophilic members were derived from microbial communities buried in the ~20 million-year-old coal-bearing sediments after the long-term survival as spores and that the deep biosphere may host more abundant gram-positive spore-forming bacteria and their spores than hitherto recognized.

A new 0.9 Ma oxygen isotope stratigraphy for a shallow-water sedimentary transect across three IODP 317 sites in the Canterbury Bight of southwest Pacific Ocean

NASA Astrophysics Data System (ADS)

Ding, Xuan; Wu, YingYing

2016-04-01

Sedimentary records in shallow-water environment provide unique opportunity to further our understanding on the regional relative sea level changes in relation to global climate change. Here we present a new 0.9 Ma oxygen isotope stratigraphy for a shallow-water sedimentary transect across three IODP 317 sites in the Canterbury Bight of southwest Pacific Ocean. The three sites are located on the eastern margin of the South Island of New Zealand, including a continental slope site, IODP317-U1352 and two continental shelf sites, IODP317-U1354 and IODP317-U1351. We first generated high resolution benthic foraminifers (Nonionella flemingi) δ18O records for the three sites and a planktonic (Globigerina bulloides) record for the U1352B. An initial chronological framework for the benthic δ18O record of the U1352B was constructed using 8 accelerator mass spectrometry (AMS) radiocarbon dates and 4 biostratigraphic events. Then a refined age model was established by correlating the U1352B benthic δ18O record with the EDC δD record on the AICC2012 time-scale, and the LR04 benthic δ18O stack. Although the U1354B and U1351B have lower sedimentation rates, their benthic δ18O records correlate well with that of U1352B. In order to ensure the accuracy of the chronostratigraphic framework established, we also analyzed the characteristics of sedimentary grain size and the planktonic and benthic δ18O values. In accord with the adjacent sites, the results show that the melt of Southern Alps glaciers due to the warming climate during MIS 11 and 5.5 led to the increased fresh water delivery, with massive terrigenous deposit; and the warm SST during the MIS7 is related with the STF migration, which led to strong current activity, with coarser grain size. Meanwhile, records of benthic δ18O, sedimentation rate and content of >63μm coarse fraction of site U1352 all indicate the MIS 20 was indeed a colder interval compared to subsequent glacial times.

Expedition 23 Docking

NASA Image and Video Library

2010-04-03

Kirk Shireman, NASA's deputy ISS program manager, answers reporter’s questions during a Soyuz post-docking press conference at the Russian Mission Control Center in Korolev, Russia on Sunday, April 4, 2010. The Soyuz TMA-18 docked to the International Space Station carrying Expedition 23 Soyuz Commander Alexander Skvortsov, Flight Engineer Mikhail Kornienko and NASA Flight Engineer Tracy Caldwell Dyson. Photo Credit: (NASA/Carla Cioffi)

Expedition 23 Docking

NASA Image and Video Library

2010-04-03

Alexei Krasnov, Director of Manned Space Programs Department, Roscosmos, listens to reporter’s questions during a Soyuz post-docking press conference at the Russian mission Control Center in Korolev, Russia on Sunday, April 4, 2010. The Soyuz TMA-18 docked to the International Space Station carrying Expedition 23 Soyuz Commander Alexander Skvortsov, Flight Engineer Mikhail Kornienko and NASA Flight Engineer Tracy Caldwell Dyson. Photo Credit: (NASA/Carla Cioffi)

Expedition 23 Docking

NASA Image and Video Library

2010-04-03

Kirk Shireman, right, NASA's deputy ISS program manager, answers reporter’s questions during a Soyuz post-docking press conference at the Russian Mission Control Center in Korolev, Russia on Sunday, April 4, 2010. The Soyuz TMA-18 docked to the International Space Station carrying Expedition 23 Soyuz Commander Alexander Skvortsov, Flight Engineer Mikhail Kornienko and NASA Flight Engineer Tracy Caldwell Dyson. Photo Credit: (NASA/Carla Cioffi)

Expedition 19 Docks to ISS

NASA Image and Video Library

2009-03-27

Alexei Krasnov, Director of Manned Space Programs Department, Roscosmos, answers reporters questions during a Soyuz post-docking press conference at the Russian mission Control Center in Korolev, Russia on Saturday March 28, 2009. The Soyuz TMA-14 docked to the International Space Station carrying Expedition 19 Commander Gennady I. Padalka, Flight Engineer Michael R. Barratt and Spaceflight Participant Charles Simonyi. Photo Credit: (NASA/Bill Ingalls)

Exploring Links Between Global Climate and Explosive Arc Volcanism in Tephra-Rich Quaternary Sediments: A Pilot Study from IODP Expedition 350 Site 1437B, Izu Bonin Rear-Arc Region

NASA Astrophysics Data System (ADS)

Corry-Saavedra, K.; Straub, S. M.; Bolge, L.; Schindlbeck, J. C.; Kutterolf, S.; Woodhead, J. D.

2015-12-01

Fallout tephra in marine sediment provide an excellent archive of explosive arc volcanism that can be directly related to the other parameters of climate change, such as ice volume data, IRD (ice-rafted debris) input, etc. Current studies are based on 'discrete' tephra beds, which are produced by major eruptions and visible with the naked eye. Yet the more common, but less explosive arc eruptions that are more continuous through time produce 'disperse' tephra, which is concealed by the non-volcanic host sediment and invisible to the eye. The proportion of disperse tephra in marine sediments is known to be significant and may be critical in elucidating potential synchronicity between arc volcanism and glacial cycles. We conducted a pilot study in young sediments of IODP Hole 1437B drilled at 31°47.3911'N and 139°01.5788'E at the rear-arc of the Izu Bonin volcanic arc. By means of δ18O (Vautravers, in revision), eleven climatic cycles are recorded in uppermost 120 meter of carbonate mud that is interspersed by cm-thick tephra fallout layers. We selected six tephra layers, ranging from 0.2 to 1.16 million years in age, and sampled those vertically, starting from carbonate mud below the basal contact throughout the typical gradational top into the carbonate mud above. From each tephra bed, volcanic particles (>125 micrometer) were handpicked. All other samples were powdered and leached in buffered acetic acid and hydroxylamine hydrochloride to remove the carbonate and authigenous fraction, respectively. Major and trace element abundances (except for SiO2) from all samples were determined by ICP-MS and ICP-OES methods. Strong binary mixing trends are revealed between the pure tephra end member, and detrital sediment component. The tephra is derived from the Izu Bonin volcanic front and rear-arc, while the sediment component is presumably transported by ocean surface currents from the East China Sea. Our data show that mixing proportions change systematically with sample percentage left after leaching and the stratigraphic position of sample, implying that the composition of the aluminosilicate fraction is an indicator of the percentage of disperse ash present in the carbonate mud. This data leave potential to investigate temporal trends. Our results are currently being refined with radiogenic isotope data.

Volcanic Cyclicities in the Pacific Northwest: Insights from the Marine Tephra Record from IODP Expedition 350, Izu Bonin Arc

NASA Astrophysics Data System (ADS)

Straub, S. M.; Schindlbeck, J. C.; Jegen, M. D.; Corry-Saavedra, K.; Murayama, M.; Woodhead, J. D.; Kutterolf, S.; Vautravers, M. J.; Wang, K. L.

2016-12-01

While the influences of orbital cycles on the ocean-atmosphere system are well documented, it remains largely unknown whether Earth's interior processes are similarly connected to orbital cycles. Recent studies of cyclic deposition in ash fallout from arc volcanism suggest that global climate changes in the form of variable glacial and water load are inversely related to magma production and/or volcanic eruption rate. However, a rigorous test of this hypotheses requires a temporally precise record of past volcanism which spans multiple glacial cycles at high resolution. The marine ash record of explosive volcanism provides such records readily. Here we undertake a detailed chemical study of discrete and disperse tephra deposits in cores from IODP Holes U1437B and U1436A drilled near the Izu Bonin arc in the northwestern Pacific. These locations combine a high background sedimentation rate (>10 m/Ma) of biogenic carbonate and Asian-derived dust with frequent emplacement of tephra fallout from the nearby Izu Bonin and Japan arcs. δ18O analyses record thirteen climatic cycles in the carbonate mud of the uppermost 120 m of Hole U1437B and eleven cycles in the uppermost 70 m of Hole U1436C. Strikingly, the distribution of 134 primary ash layers in Hole U1437B seems to be synchronous with glacial cycles, with a distinct increase in eruption occurrences at either the transitions of glacial/interglacial or at the early interglacials. This is confirmed by first results of a frequency analysis of the ash-time series that indicate a dominance of a 100 ka cycle. The question, which remains to be answered, is whether deglaciation drives volcanism or volcanism drives deglaciation? We also investigate the distribution of `dispersed ash' in this sequence, which is not visible to the naked eye but is volumetrically significant and thus also critical in testing time-cause relationships between arc volcanism and glacial cycles. Major questions we address are: 1) do we see the same cyclic behavior between dispersed ash and discrete ash layers?, 2) does this cyclicity following orbital cycles and 3) is the distribution of tephra layers controlled by orbital cycles or do the tephras reflect the cyclic deposition of the host sediment?

3D seismic structure of the Zhenbei-Huangyan seamount chain in the East sub-basin of the South China Sea and its mechanism of formation

NASA Astrophysics Data System (ADS)

Zhao, M.; Wang, J.; Qiu, X.; Sibuet, J. C.; He, E.; Zhang, J.

2015-12-01

The post-spreading volcanic ridge (PSVR) is oriented approximately E-W in its western part called the Zhenbei-Huangyan seamount chain. Where is the extinct spreading ridge (ESR) of the East Sub-basin located? beneath the PSVR (Li et al., 2014)? Or intersecting with the PSVR by N055° orientation (Sibuet et al., submitted)? A three-dimensional Ocean Bottom Seismometer (OBS) survey covered both the central extinct spreading ridge and the Zhenbei-Huangyan seamount chain, the IODP Site U1431 (Li et al., 2014) being located just north of the chain. The results of this experiment will provide the essential information to understand the emplacement of the PSVR within the previously formed oceanic crust. The comprehensive seismic record sections of 39 OBSs are of high quality and show clear and reliable P-wave seismic phases, such as Pg, Pn and PmP. These seismic arrivals provide strong constrains for modeling the detailed three-dimensional velocity structure. We will show that the crust is oceanic on each side of the Zhenbei-Huangyan seamount chain, where is the location of the ESR and what is the genetic relationship between the magma chambers and the overlying Zhenbei-Huangyan seamount chain. We suggest that the large thickness of the upper crust is possibly due to volcanic extrusions and the thickened lower crust to magmatic underplating. Combining previous geochemical study of PSVR outcropping samples, the formation mechanism of the seamount chain might be explained by a buoyancy decompression melting mechanism (Castillo et al., 2010). This research was granted by the Natural Science Foundation of China (91028002, 91428204, 41176053). ReferencesSibuet J.-C., Yeh Y.-C. and Lee C.-S., 2015 submitted. Geodynamics of the South China Sea: A review with emphasis on solved and unsolved questions. Tectonophysics. Li, C. F., et al. 2014. Ages and magnetic structures of the South China Sea constrained by deep tow magnetic surveys and IODP Expedition 349. Geochemistry, Geophysics, Geosystems, 15, 4958-4983. Castillo, P. R., Clague, D. A., Davis, A. S., Lonsdale, P. F., 2010. Petrogenesis of Davidson Seamount lavas and its implications for fossil spreading center and intraplate magmatism in the eastern Pacific. Geochemistry, Geophysics, Geosystems, 11, Q02005, doi:10.1029/2009GC002992.

Coccolith concentrations in the Gulf of Cadiz at the IODP Site U1390 (Exp 339), in the last ~20,000 years

NASA Astrophysics Data System (ADS)

Angulo, M.; Balestra, B.

2013-12-01

Our project is dedicated to the study of sediment samples gathered from the Gulf of Cadiz during the Integrated Ocean Drilling Project (IODP), Expedition 339 at Site U1390. The Gulf of Cadiz is an area of the Atlantic Ocean located directly south of Portugal and the western end of the Strait of Gibraltar. We analyzed the sediment samples to obtain the numbers of coccoliths per gram of sediment in each sample. Coccolithophores (from which the coccoliths are the fossils that remain in the sediments) are one of the most abundant groups of living phytoplankton and they are significant components of marine sediment. In order to prepare our samples for counting (the process by which we determined the number of coccoliths in our samples) we utilized about 23 samples from the uppermost 17 meters of the sediment core. This process involved collecting subsamples of each individual sample and then oven drying them. Then we weighted them by utilizing a microbalance to collect the desired amount of sample we needed (between 2 and 4 mg). Several of our samples were slightly below and above this desired amount due to human error. Once we gathered the desired amount of samples for our project, we proceeded to use a filtration system to obtain filters. Then we put the filters into an oven to dry them. After the samples were dried over the course of a day, we proceeded to prepare them for viewing through the microscope. To do this, we cut the filter and placed it upon a microscope slide. Then, we applied oil to the slide, cover and placed it under the Light Microscope (LM). We looked at five different views in each filters under the microscope, counting the number of coccoliths in each view. The counting has been expressed in terms of numbers of coccoliths per gram of sediment (total coccolith concentration). Our results showed us that the amount of coccoliths in the sediment samples receded during the cold periods of time, such as an ice age, and fluctuated in an upward pattern as the climate warmed. This project was part of a first step for further research, namely to continue to determine how climate has changed in the past ~20,000 years in the investigated area.

Geology of the Wilkes Land Sub-basin and Stability of the East Antarctic Ice Sheet: Insights from rock magnetism at IODP Site U1361

NASA Astrophysics Data System (ADS)

Tauxe, L.; Sugisaki, S.; Jimenez-Espejo, F. J.; Cook, C. P.; van de Flierdt, T.; Iwai, M.; Escutia, C.

2014-12-01

IODP Expedition 318 drilled Site U1361 on the continental rise offshore of the Wilkes sub-glacial basin. The goal was to reconstruct the stability of the East Antarctic Ice Sheet (EAIS) during Neogene warm periods. Teasing out the paleoenvironmental implications is essential for understanding the evolution of the EAIS. Anisotropy of magnetic susceptibility (AMS) is sensitive to differential compaction and other rock magnetic parameters like isothermal remanence and anhysteretic remanence are very sensitive to changes in the terrestrial source region. In general, highly anisotropic layers correspond with laminated clay-rich units, while more isotropic layers are bioturbated and have less clay. Layers enriched in diatoms are associated with the latter, which also have higher Ba/Al ratios indicating higher productivity. Higher anisotropy layers have lower porosity and moisture contents and have fine grained magnetic mineralogy dominated by magnetic. Higher anisotropy layers are dominated by maghemite, supporting the suggestion by Cook et al. (2013) of different source regions during low and high productivity times. They tied the two facies to the coastal outcrops of the Lower Paleozoic granitic terranes and the Ferrar Large Igneous Province in the more inland Wilkes Subglacial Basin respectively. Here we present evidence for a third geological unit, one eroded at the boundaries between the high and low clay zones with a "hard" (hematite) dominated magnetic mineralogy. This unit likely outcrops in the Wilkes sub-glacial basin and could be hydrothermally altered Beacon sandstone similar to that detected by Craw and Findlay (1984) in Taylor Valley or the equivalent to the Elatina Formation in the Adelaide Geosyncline in Southern Australia (Schmidt and Williams, 2013). Cook, C. P., van de Flierdt, T., Williams, T., Hemming, S. R., Iwai, M., Kobayashi, M., Jimenez-Espejo, F., Escutia, C., Gonzalez, J., Khim, B. K., McKay, R., Passchier, S., Bohaty, S., Riesselman, C. R., Tauxe, L., Sugisaki, S., Lopez Galindo, A., Patterson, M. O., Sangiorgi, F., Pierce, E. L., Brinkhuis, H., and Scientists, I. E., 2013, Nature Geoscience, v. 6, p. 765-769. Craw, D., and Findlay, R. H., 1984, New Zealand Jour. Geol. Geophys., v. 27, p. 465-475. Schmidt, P. W., and Williams, G. E., 2013, Global and Planetary Change, v. 110, p. 289-301.

Application of individual foraminifera Mg/Ca and δ18O analyses for paleoceanographic reconstructions in the Bay of Bengal and other active depositional environments

NASA Astrophysics Data System (ADS)

Fritz-Endres, T.; Dekens, P.; Fehrenbacher, J. S.; Spero, H. J.; Stine, A.

2017-12-01

Paleoceanographic research traditionally focuses on regions where sediment deposition is minimally affected by transport. However, sediment fans near tectonically active regions provide an opportunity to link oceanographic climate to terrestrial processes. Sediment cores recovered during IODP Expedition 354 in the Bay of Bengal include hemipelagic sections that record the history of tectonic uplift and the development of the Indian Monsoon through the last 10 Ma. Although these cores provide a unique opportunity to link marine and terrestrial climate, the complex depositional environment requires that the source of foraminifera is carefully considered before using these proxies to reconstruct oceanographic conditions. Foraminifera in Bengal Fan sediments may have been transported via turbidity currents from the northern Bay of Bengal, where the seasonal variability of SST and SSS is larger compared to the southern Bay of Bengal. We measured single Globigerinoides sacculifer Mg/Ca and δ18O from mudline samples of IODP Site U1454 (8.4°N, 85.5°E, 3721 m water depth) near the modern active channel and Site U1449 (8.4°N, 88.7°E, 3653 m water depth) far from channel activity. We compare these sites to single G. sacculifer from the core-top sample of Site 342KL (20.6°N, 90.1°E, 1256 m water depth) located on the continental shelf. Each foraminifera lives 2-4 weeks and the distribution of 60 to 80 data points reflects the seasonal range of SST and SSS at the location where the foraminifera calcified. Measurements in foraminifera from Site U1449 (away from active channel) are statistically different from the site in the northern Bay of Bengal and more consistent with local conditions. Conversely, foraminifera from the site near the active channel reflect a combined signal of local conditions recorded from the site far from channel activity and those recorded from the continental shelf. This suggests a portion of foraminifera from the active channel site have been transported from the northern Bay of Bengal. Our data show that foraminifera can be used to reconstruct SST and δ18O in this complex depositional environment, but caution must be taken when the down-core lithology indicates turbidites and possible sediment transport

Nature and tectonic implications of uneven sedimentary filling of the South China Sea oceanic basin

NASA Astrophysics Data System (ADS)

Yin, Shaoru; Li, Jiabiao; Ding, Weiwei; Fang, Yinxia

2017-04-01

The IODP Expedition 349 in 2014, for the first time, illustrated significant differences of sediment rate and lithology in the central South China Sea (SCS) oceanic basin. Based on seismic reflection profiles tied to IODP349 drilling data, we investigated characteristics of sedimentary filling of the whole SCS oceanic basin, and examined their implications for tectonics. Results show that sediments fill the SCS oceanic basin mainly in three depositional patterns. Firstly, during the Oligocene to middle Miocene, sediments amassed almost solely and then connected like a band parallel to the continent in a low average sediment rate (<10 m/Myr) in the northern oceanic basin. These sediments were deposited mainly in the form of submarine fans and mass transport deposits. Sediments were predominately supplied by the Red and Pearl Rivers and the Dongsha Islands. The sedimentary characteristics likely reflect the latest early Miocene end of seafloor spreading of the SCS and the first-phase rapid uplift of the Tibetan Plateau. Secondly, during the late Miocene, deposition mainly occurred in the Northwest Sub-basin and extended southeastward with a middle average sediment rate ( 30 m/Myr). Sediments were mostly transported by the Red River and Xisha Trough and deposited in the form of submarine fans. The abnormal increase of sediment rate in the Northwest Sub-basin reflects late Miocene slip reversal of the Red River Fault. Finally, since the Pliocene, sediments gradually propagated northeastward in the Southwestern Sub-basin, and accumulated rapidly in the southeastern and northeastern basin, especially in the northern Manila Trench during the Quaternary, in an average sediment rate about 60-80 m/Myr. These sediments were transported mainly by submarine canyons and settled in the form of submarine fans and canyon-overbank deposition. Sediments came from four major sources, including Taiwan, Dongsha Islands, Mekong River, and northern Palawan. The Pliocene to Quaternary explosion of uneven sedimentary filling in the SCS oceanic basin points to the combined action of local and regional tectonics, including the two-phase rapid uplift of the Tibetan Plateau, the Pliocene to Quaternary increased northwestward movement of the Philippine Sea plate and Dongsha event. This study exhibits hitherto most completed observation of sedimentary filling of the SCS oceanic basin and provides new geophysical evidences for the local and regional important tectonics.

Direct Observations of In Situ Stress State in a 3 Kilometer Deep Borehole in the Upper Plate, Nankai Trough Subduction Zone: IODP Site C0002

NASA Astrophysics Data System (ADS)

Tobin, H. J.; Saffer, D. M.; Castillo, D. A.; Hirose, T.

2016-12-01

During IODP Expedition 348, borehole C0002F/N/P was advanced to a depth of 3058 m below the seafloor (mbsf) into the inner forearc accretionary wedge of the Nankai subduction zone (SW Japan), now the deepest scientific drilling ever into the ocean floor. The goals were to investigate the physical properties, structure, and state of stress deep within the hanging wall of a seismogenic subduction plate boundary. Mud pressure and gas monitoring, injection tests, leak-off tests (LOT), logging-while-drilling (LWD) measurements, and observations of mud losses and hole conditions provide both direct and indirect information about in situ pore pressure and stress state. The LOTs show that the minimum principal stress is consistently less than the vertical stress defined by the overburden, ruling out a thrust faulting stress state throughout the drilled section, and define a nearly linear gradient in Shmin from the seafloor to the base of the hole. Observations of mud loss and the lack of observed gas shows indicate that formation pore fluid pressure is not significantly (< 10 MPa) greater than hydrostatic. The maximum horizontal stress, estimated from borehole breakout width and pressure spikes during pack-off events, is close in magnitude to the vertical stress. Therefore the accretionary prism lies in either a normal or strike-slip faulting regime, or is transitional between the two, from 1 to 3 km depth. At 3002 mbsf we estimate that the effective stresses are: Sv' = 33 MPa; SHmax' = 25-36 MPa; and Shmin' = 18.5-21 MPa. Differential stresses are therefore low, on the order of 10-12 MPa, in the hanging wall of the subduction thrust. We conclude that (1) the inner wedge is not critically stressed in horizontal compression; (2) basal traction along the megathrust must be low in order to permit concurrent locking of the fault and low differential stresses deep within the upper plate; and (3) although low differential stresses may persist down to the plate boundary at 5000 mbsf, the maximum horizontal stress SHmax must transition to become greater than the vertical stress, either spatially below the base of the borehole, or temporally leading up to megathrust fault rupture, in order to drive slip on the megathrust.

Reconstructing palaeo-environmental conditions in the Baltic: A multi-proxy comparison from IODP Site M0059 (Little Belt)

NASA Astrophysics Data System (ADS)

Kotthoff, Ulrich; Andrén, Thomas; Bauersachs, Thorsten; Fanget, Anne-Sophie; Granoszewski, Wojciech; Groeneveld, Jeroen; Krupinski, Nadine; Peyron, Odile; Stepanova, Anna; Cotterill, Carol

2015-04-01

Some of the largest marine environmental impacts from ongoing global climate change are occurring in continental shelf seas and enclosed basins, including severe oxygen depletion, intensifying stratification, and increasing temperatures. In order to predict future changes in water mass conditions, it is essential to reconstruct how these conditions have changed in the past. The brackish Baltic Sea is one of the largest semi-enclosed basins worldwide, and hence provides a unique opportunity to analyse past changes. IODP Expedition 347 recovered a unique set of long sediment cores from the Baltic Sea Basin which allow new high-resolution reconstructions. The application of existing and development of new proxies in such a setting is complicated, as environmental changes often occur on much faster time scales with much larger variations. Therefore, we present a comparison of commonly used proxies to reconstruct palaeoecosystems, -temperatures, and -salinity from IODP Site M0059 in the Little Belt. The age model for Site M0059 is based on 14C dating and biostratigraphic correlation with neighbouring terrestrial pollen records. The aim of our study is to reconstruct the development of the terrestrial and marine ecosystems in the research area and the related environmental conditions, and to identify potential limitations for specific proxies. Pollen is used as proxy for vegetation development in the hinterland of the southern Baltic Sea and as land/air-temperature proxies. By comparison with dinoflagellate cysts and green algae remains from the same samples, a direct land-sea comparison is provided. The application of the modern analogues technique to pollen assemblages has previously yielded precise results for late Pleistocene and Holocene datasets including specific information on seasonality, but pollen-based reconstructions for Northern Europe may be hampered by plant migration effects. Chironomid remains are used where possible as indicators for surface water conditions during the warm season. Analyses of palynomorphs and chironomids are complemented with the analysis of lipid palaeothermometers, such as TEX86 and the long chain diol index (LDI), which both allow reconstructing variation in sea surface temperatures (SST) of the Baltic Sea. In addition, the MBT/CBT proxy is used to infer past changes in mean annual air temperatures (MAAT) and the diol index (DI) to determine variation in salinity of the Baltic Sea's surface waters over the investigated time period. The low salinity (25 psu) of the Little Belt is a potential limitation for several of the used proxies, which could lead to under-estimation of paleo-temperatures. To quantitatively and qualitatively estimate the impact of salinity, δ18O measurements (monospecific) and faunal assemblage analyses are performed on benthic foraminifera as well as ostracod faunal assemblages, which are especially sensitive to bottom water salinity changes. The results of this inter-comparison study will be useful for the reconstruction of gradients between different settings, e.g. how water column stratification developed, possibly if and how changes in seasonality occurred, and to identify the circumstances under which specific proxies may be affected by secondary impacts.

Two Commemorative Expeditions to Celebrate the Return to Totality

NASA Astrophysics Data System (ADS)

Thompson, Kristen; English, Tom

2018-01-01

Throughout history, total solar eclipses have generated excitement across the scientific community, as they provide a unique opportunity to study the Sun’s corona. Occurrences of such events have prompted many American astronomy programs to organize expeditions aimed at studying and photographing the eclipse. Only two observing stations from any of the major 19th and early 20th century eclipse expeditions were once again found in the path of totality of the 21 August 2017 Great American Eclipse. These stations, one in Newberry, SC and the other in Winnsboro, SC, were located in the shadow of the 28 May 1900 eclipse that passed through the southeastern United States from New Orleans to Norfolk. To celebrate this unique opportunity, we organized two expeditions that travelled to these towns to commemorate their return to totality. In this talk, I will describe the circumstances of the 1900 solar eclipse, our modern expeditions, and our effort to bring this eclipse history to life for the community.

USEPA'S SITE PROGRAM IMPACT ON THE DEVELOPMENT AND USE OF INNOVATIVE HAZARDOUS WASTE TREATMENT

EPA Science Inventory

The USEPA's SITE Program was created to meet the increased demand for innovative technologies for hazardous waste treatment. The primary mission of the SITe Program is to expedite the cleanup of sites on the NPL. The SITE Program has two components: The Demonstration Program and ...

75 FR 29366 - ``Homeless Veterans' Reintegration Program (HVRP) National Technical Assistance Center...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-25

... ``Homeless Veterans' Reintegration Program (HVRP) National Technical Assistance Center Cooperative Agreement...). Section 2021 authorizes programs to expedite the reintegration of homeless Veterans into the labor force... Technical Assistance Center (NTAC) for the Homeless Veterans' Reintegration Program (HVRP) to include the...

Bringing cutting-edge Earth and ocean sciences to under-served and rural audiences through informal science education

NASA Astrophysics Data System (ADS)

Cooper, S. K.; Petronotis, K. E.; Ferraro, C.; Johnson, K. T. M.; Yarincik, K.

2017-12-01

The International Ocean Discovery Program (IODP) is an international marine research collaboration that explores Earth's history and dynamics using ocean-going research platforms to recover data recorded in seafloor sediments and rocks and to monitor subseafloor environments. The JOIDES Resolution is the flagship vessel of IODP and is operated by the National Science Foundation. It is an inspirational hook for STEM Earth and ocean topics for children and the general public of all ages, but is not easily accessible due to its international travels and infrequent U.S. port calls. In response, a consortium of partners has created the Pop-Up/Drill Down Science project. The multi-year project, funded by NSF's Advancing Informal Science Learning program, aims to bring the JR and its science to under-served and rural populations throughout the country. Consisting of an inflatable walk-through ship, a multi-media experience, a giant interactive seafloor map and a series of interactive exhibit kiosks, the exhibit, entitled, In Search of Earth's Secrets: A Pop-Up Science Encounter, will travel to 12 communities throughout the next four years. In each community, the project will partner with local institutions like public libraries and small museums as hosts and to train local Girl Scouts to serve as exhibit facilitators. By working with local communities to select events and venues for pop-up events, the project hopes to bring cutting edge Earth and ocean science in creative new ways to underserved populations and inspire diverse audiences to explore further. This presentation will provide details of the project's goals, objectives and development and provide avenues to become involved.

Exploring Metabolic Activities of Deeply Buried Microbial Communities in Oxic Sediments Underlying Oligotrophic Open Ocean Gyres

NASA Astrophysics Data System (ADS)

Ziebis, W.; Patel, A.; Krupke, A.; Ferdelman, T. G.

2012-12-01

The vast majority of scientific drilling expeditions have focused on continental margins where oxygen is depleted within the surface (1 m) layer of the sediment and buried organic carbon sustains anaerobic microbial communities. IODP expeditions 329 (South Pacific Gyre) and 336 (Mid-Atlantic Ridge - North Pond) took place in oligotrophic open ocean regions, which constitute 48% of the world ocean. These expeditions have revealed that unlike continental margins the seafloor underneath oligotrophic ocean gyres is oxic. Within the South Pacific Gyre (SPG) dissolved oxygen persists throughout the sediment cover and reaches the basement even at the sites with thickest sediment cover (62 and 75 mbsf). North Pond is a sedimented pond (< 300 m sediment cover) located on the flank of the Mid-Atlantic Ridge underlying the oligotrophic central Atlantic. Here, oxygen diffuses upward from the basaltic aquifer underlying the sediment package in addition to deep oxygen penetration from the overlying water. Oxygen is the main electron acceptor available for sub-seafloor microbial activity in these vast oligotrophic open ocean regions. Microbial cells are present and active in the organic poor sediments, albeit numbers are near or below the detection limit (<103 cm-3 sediment) in the extremely organic-poor sediment of the SPG (below 2 -15 m sediment depth, depending on the location). However, we have very limited knowledge on the microbial community compositions and metabolic activities. Even the dominance of bacteria or archaea remains largely elusive. It has been suggested that while archaea dominate in the anoxic sediments of continental margins bacteria might be more abundant in the oxic seafloor underlying oligotrophic ocean gyres where aerobic respiration prevails. Experiments were conducted with sediment samples from the SPG and North Pond to explore the pattern of microbial diversity and metabolic activity using a suite of radio and stable isotopes in combination with single cell analyses. Our goal was to track the uptake and turnover of metabolically important elements (C, N, P) and to compare metabolic activities (heterotrophy / autotrophy) between sites and with depth. Labeling of cells using fluorescent oligonucleotide probes (HISH and CARD-FISH) in combination with nanoSIMS has thus far revealed a clear dominance of bacteria in SPG sub-seafloor sediments, which showed a high uptake of nitrogen (ammonium). Current experiments using cell extractions and cell encapsulations followed by incubations with radiotracers will further reveal carbon turnover pathways of specific microorganisms.