Antarctic climate, Southern Ocean circulation patterns, and deep water formation during the Eocene

NASA Astrophysics Data System (ADS)

Huck, Claire E.; van de Flierdt, Tina; Bohaty, Steven M.; Hammond, Samantha J.

2017-07-01

We assess early-to-middle Eocene seawater neodymium (Nd) isotope records from seven Southern Ocean deep-sea drill sites to evaluate the role of Southern Ocean circulation in long-term Cenozoic climate change. Our study sites are strategically located on either side of the Tasman Gateway and are positioned at a range of shallow (<500 m) to intermediate/deep ( 1000-2500 m) paleowater depths. Unradiogenic seawater Nd isotopic compositions, reconstructed from fish teeth at intermediate/deep Indian Ocean pelagic sites (Ocean Drilling Program (ODP) Sites 738 and 757 and Deep Sea Drilling Project (DSDP) Site 264), indicate a dominant Southern Ocean-sourced contribution to regional deep waters (ɛNd(t) = -9.3 ± 1.5). IODP Site U1356 off the coast of Adélie Land, a locus of modern-day Antarctic Bottom Water production, is identified as a site of persistent deep water formation from the early Eocene to the Oligocene. East of the Tasman Gateway an additional local source of intermediate/deep water formation is inferred at ODP Site 277 in the SW Pacific Ocean (ɛNd(t) = -8.7 ± 1.5). Antarctic-proximal shelf sites (ODP Site 1171 and Site U1356) reveal a pronounced erosional event between 49 and 48 Ma, manifested by 2 ɛNd unit negative excursions in seawater chemistry toward the composition of bulk sediments at these sites. This erosional event coincides with the termination of peak global warmth following the Early Eocene Climatic Optimum and is associated with documented cooling across the study region and increased export of Antarctic deep waters, highlighting the complexity and importance of Southern Ocean circulation in the greenhouse climate of the Eocene.

Technical note: Late Pliocene age control and composite depths at ODP Site 982, revisited

NASA Astrophysics Data System (ADS)

Khélifi, N.; Sarnthein, M.; Naafs, B. D. A.

2012-01-01

Ocean Drilling Program (ODP) Site 982 provided a key sediment section at Rockall Plateau for reconstructing northeast Atlantic paleoceanography and monitoring benthic δ18O stratigraphy over the late Pliocene to Quaternary onset of major Northern Hemisphere glaciation. A renewed hole-specific inspection of magnetostratigraphic reversals and the addition of epibenthic δ18O records for short Pliocene sections in holes 982A, B, and C, crossing core breaks in the δ18O record published for Hole 982B, now imply a major revision of composite core depths. After tuning to the orbitally tuned reference record LR04, the new composite δ18O record results in a hiatus, where the Kaena magnetic subchron might have been lost, and in a significant age reduction for all proxy records by 130 to 20 ky over the time span 3.2-2.7 million years ago (Ma). Our study demonstrates the general significance of reliable composite-depth scales and δ18O stratigraphies in ODP sediment records for generating ocean-wide correlations in paleoceanography. The new concept of age control makes the late Pliocene trends in SST (sea surface temperature) and atmospheric pCO2 at Site 982 more consistent with various paleoclimate trends published from elsewhere in the North Atlantic.

Marine Export Production and Remineralization During Early Eocene Hyperthermal Events at ODP Site 1263, Walvis Ridge, ODP Site 1209, Shatsky Rise and ODP Site 1215, Equatorial Pacific Ocean

NASA Astrophysics Data System (ADS)

Lewis, A.; Griffith, E. M.; Thomas, E.; Winguth, A. M. E.

2017-12-01

Understanding the impacts of global hyperthermal events on marine productivity and remineralization is important for understanding the reaction of the ocean to major climate change. Marine export production and remineralization was reconstructed using marine (pelagic) barite accumulation rates (BAR) coupled with records of benthic foraminiferal assemblages across the Paleocene - Eocene Thermal Maximum (PETM) at 55.3 Ma, Eocene Thermal Maximum 2 (ETM2) 2 Ma later, and ETM3 3.1 Ma after the PETM. Marine barite accumulates in deep sea sediment precipitating in the overlying water column during degradation of organic matter exported from the photic zone. Foraminiferal data indicate the amount of organic matter reaching the seafloor. We use the difference between these records to infer changes in rates of remineralization. We present data from ODP Site on Walvis Ridge, Southeastern Atlantic; ODP Site 1209 on Shatsky Rise, North Pacific; and ODP Site 1215, equatorial Pacific. Sites 1263 and 1215 had maximum BAR roughly centered over the maximum negative PETM CIE, whereas at Site 1209 the maximum was before the PETM. The maximum BAR across ETM2 and ETM3 (0.5 and 0.25 of that at the PETM, respectively) was centered over the maximum negative CIE at Site 1263. At Site 1209, the BAR (0.5 the maximum value before the PETM) peaked before ETM2. Barite concentration at Site 1215 was low across at the smaller hyperthermals, but the onset of ETM2 had a maximum value < 3% of the PETM, whereas the ETM3 maximum occurred during the CIE recovery and was < 10% of ETM2. Benthic foraminiferal data indicate decreased food arrival at the seafloor during elevated BAR, thus indicating enhanced remineralization. During the PETM, at all 3 sites, increases in barite coincided with reduced BFAR. Similar trends were observed during ETM2 at Sites 1263 and 1215, suggesting dramatic changes in remineralization over all hyperthermal events at these sites. Increased remineralization rates could partly account for differences in planktonic and benthic extinction, as observed during the PETM.

Paleolatitude Records of the Western Pacific as Determined From DSDP/ODP Basaltic Cores

NASA Astrophysics Data System (ADS)

Liu, Q.; Zhao, X.; Yan, M.; Riisager, P.; Lo, C.

2008-12-01

We report here the new paleomagnetic, rock magnetic, and Ar-Ar geochronologic results of our recent completed project, which aims to determine the Cretaceous paleomagnetic paleolatitude record and the architecture of the volcanic basins in the western Pacific Ocean. The new results, in concert with our paleomagnetic research on ODP rocks recovered from the Ontong Java Plateau (OJP), suggest that various plateaus and basins in the western Pacific had similar plate-tectonic setting (paleolatitude) and ages with that of OJP at time of emplacement (~120 Ma). Basalts sampled from Deep Sea Drilling Project (DSDP) and Ocean Drilling Program (ODP) sites of the greater OJP as well as from obducted sections in the Solomon Islands of Malaita and Santa Isabel are strikingly uniform in petrologic and geochemical characteristics. Many of these cores, especially those from DSDP sites, have not been well-studied paleomagnetically and hence underutilized for tectonic study. We carefully re-sampled and systematic demagnetized and analyzed 925 basaltic cores from 15 sites drilled by10 DSDP/ODP Legs in the western and central Pacific, which represents a unique possibility for averaging out secular variation to obtain a well-defined paleolatitude estimate. The most important findings from this study include: (1). most basins formed during the Cretaceous long normal magnetic period with similar Ar-Ar ages as the OJP; (2) East Mariana, Pigafetta, the upper flow unit in the Nauru basin and Mid-Pacific Guyots all yielded similar paleolatitudes as those for OJP, suggesting the volcanic eruptions of flows in these basins are likely related to the emplacement of the OJP; and (3) the lower flow unit in the Nauru basin yields a paleolatitude that is ~10° further south and the age is more than 10 m.y. older than these of the OJP.

Japan signs Ocean Agreement

NASA Astrophysics Data System (ADS)

The Ocean Research Institute of the University of Tokyo and the National Science Foundation (NSF) have signed a Memorandum of Understanding for cooperation in the Ocean Drilling Program (ODP). The agreement calls for Japanese participation in ODP and an annual contribution of $2.5 million in U.S. currency for the project's 9 remaining years, according to NSF.ODP is an international project whose mission is to learn more about the formation and development of the earth through the collection and examination of core samples from beneath the ocean. The program uses the drillship JOIDES Resolution, which is equipped with laboratories and computer facilities. The Joint Oceanographic Institutions for Deep Earth Sampling (JOIDES), an international group of scientists, provides overall science planning and program advice regarding ODP's science goals and objectives.

A Comparison of two Brunhes Chron Geomagnetic Excursions Recorded by Neighbouring North Atlantic Sites (ODP Sites 1062 and 1063)

NASA Astrophysics Data System (ADS)

Bourne, M.; Mac Niocaill, C.; Knudsen, M. F.; Thomas, A. L.; Henderson, G. M.

2012-04-01

A full picture of geomagnetic field behaviour during the Blake excursion is currently limited by a paucity of robust, high-resolution records of this ambiguous event. Some records seem to point towards a 'double-excursion' character whilst others fail to record the Blake excursion at all. We present here a high-resolution record of the Blake excursion obtained from Ocean Drilling Program (ODP) Site 1062 on the Blake Outer Ridge (ODP Leg 172). Palaeomagnetic measurements in three cores reveal a single excursional feature associated with a broad palaeointensity low, characterised by rapid transitions (less than 500 years) between a stable normal polarity and a fully-reversed, pseudo-stable polarity. A relatively high sedimentation rate (~10 cm kyr-1) allows the determination of transitional field behaviour during the excursion. Rather than assuming a constant sedimentation rate between assigned age tie-points, we employ measurements of 230Thxs concentrations in the sediment to assess variations in the sedimentation rates through the core sections of interest. This allows us to determine an age and duration for the two excursions with greater accuracy and known uncertainty. Our new age model gives an age of 127 ka for the midpoint of the Blake event at Site 1062. The age model also gives a duration for the directional excursion of 7.1±1.6 kyr. This duration is similar to that previously reported for the Iceland Basin Excursion (~185 ka) from the nearby Bermuda Rise (ODP Site 1063), which recorded a ~7-8 kyr event. Similarly, a high sedimentation rate (10-15 cm kyr-1) at this site allows a high-resolution reconstruction of the geomagnetic field behaviour during the Iceland Basin Excursion. The Site 1063 palaeomagnetic record suggests more complicated behaviour than that of the Blake excursion at Site 1062. Instead, transitional VGP paths are characterised by stop-and-go behaviour between VGP clusters that may be related to long-standing thermo-dynamic features of the core-mantle system. The long duration of fully reversed directions at the two sites is somewhat longer than that typically assumed for excursions and appears to suggest that there may be a degree of stability associated with the two excursional events. We will present a comparison of the geomagnetic field behaviour of the two excursions as recorded at these two sites.

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.

Scientific Ocean Drilling: A Legacy of ODP Education and Community Engagement by JOI/USSSP

NASA Astrophysics Data System (ADS)

Johnson, A.; Cortes, M.; Farrell, J. W.

2003-12-01

The U.S. Science Support Program (USSSP) was established in 1986 to support the participation of U.S. scientists in the international Ocean Drilling Program (ODP). Since inception, USSSP has been managed by Joint Oceanographic Institutions (JOI), through a cooperative agreement with NSF, and guided by the U.S. Science Advisory Committee (USSAC). One of USSSP's primary goals has been to enhance the scientific contribution of ocean drilling and to maintain its vitality through a broad range of education and outreach activities. USSSP's first educational program, the Schlanger Ocean Drilling Fellowship, was established to encourage doctoral candidates to conduct research aboard the ODP drill ship, JOIDES Resolution. Since 1987, 74 fellowships have been awarded and the program has been expanded to include shorebased ODP-related research and Masters degree candidates. USSSP's second major educational activity is the Distinguished Lecturer Series. To date, 70 scientists have spoken about their ODP research at 334 institutions, effectively reaching new and diverse educational communities. In addition, USSSP has developed and distributed two interactive educational CD-ROMs (ODP: Mountains to Monsoons and Gateways to Glaciation) and an educational poster (Blast from the Past). All three items are popular supplements in classrooms from middle school to college because they present accessible scientific content, demonstrate the scientific method, and illustrate the collaborative and international nature of scientific research. USSSP's outreach efforts have included publishing the JOI/USSAC Newsletter since 1988 and ODP's Greatest Hits (abstracts written by U.S. scientists). The latter is broadly used because it communicates exciting scientific results in lay terms. USSSP has sponsored other educational efforts including a workshop to seek recommendations for educational activities to be associated with future scientific ocean drilling. NSF is currently considering the response to their solicitation of proposals to manage a successor program to USSSP, which will support the involvement of U.S. scientists in the new Integrated Ocean Drilling Program. The educational and outreach component of the new USSSP will target students at all levels, building upon improving on the USSSP-ODP achievements.

Calculating Trajectories And Orbits

NASA Technical Reports Server (NTRS)

Alderson, Daniel J.; Brady, Franklyn H.; Breckheimer, Peter J.; Campbell, James K.; Christensen, Carl S.; Collier, James B.; Ekelund, John E.; Ellis, Jordan; Goltz, Gene L.; Hintz, Gerarld R.;

Map_plot and bgg_plot: software for integration of geoscience datasets

NASA Astrophysics Data System (ADS)

Gaillot, Philippe; Punongbayan, Jane T.; Rea, Brice

2004-02-01

Since 1985, the Ocean Drilling Program (ODP) has been supporting multidisciplinary research in exploring the structure and history of Earth beneath the oceans. After more than 200 Legs, complementary datasets covering different geological environments, periods and space scales have been obtained and distributed world-wide using the ODP-Janus and Lamont Doherty Earth Observatory-Borehole Research Group (LDEO-BRG) database servers. In Earth Sciences, more than in any other science, the ensemble of these data is characterized by heterogeneous formats and graphical representation modes. In order to fully and quickly assess this information, a set of Unix/Linux and Generic Mapping Tool-based C programs has been designed to convert and integrate datasets acquired during the present ODP and the future Integrated ODP (IODP) Legs. Using ODP Leg 199 datasets, we show examples of the capabilities of the proposed programs. The program map_plot is used to easily display datasets onto 2-D maps. The program bgg_plot (borehole geology and geophysics plot) displays data with respect to depth and/or time. The latter program includes depth shifting, filtering and plotting of core summary information, continuous and discrete-sample core measurements (e.g. physical properties, geochemistry, etc.), in situ continuous logs, magneto- and bio-stratigraphies, specific sedimentological analyses (lithology, grain size, texture, porosity, etc.), as well as core and borehole wall images. Outputs from both programs are initially produced in PostScript format that can be easily converted to Portable Document Format (PDF) or standard image formats (GIF, JPEG, etc.) using widely distributed conversion programs. Based on command line operations and customization of parameter files, these programs can be included in other shell- or database-scripts, automating plotting procedures of data requests. As an open source software, these programs can be customized and interfaced to fulfill any specific plotting need of geoscientists using ODP-like datasets.

Neogene ice volume and ocean temperatures: Insights from infaunal foraminiferal Mg/Ca paleothermometry

NASA Astrophysics Data System (ADS)

Lear, Caroline H.; Coxall, Helen K.; Foster, Gavin L.; Lunt, Daniel J.; Mawbey, Elaine M.; Rosenthal, Yair; Sosdian, Sindia M.; Thomas, Ellen; Wilson, Paul A.

2015-11-01

Antarctic continental-scale glaciation is generally assumed to have initiated at the Eocene-Oligocene Transition, yet its subsequent evolution is poorly constrained. We reconstruct changes in bottom water temperature and global ice volume from 0 to 17 Ma using δ18O in conjunction with Mg/Ca records of the infaunal benthic foraminifer, O. umbonatus from Ocean Drilling Program (ODP) Site 806 (equatorial Pacific; ~2500 m). Considering uncertainties in core top calibrations and sensitivity to seawater Mg/Ca (Mg/Ca)sw, we produce a range of Mg/Ca-temperature-Mg/Casw calibrations. Our favored exponential temperature calibration is Mg/Ca = 0.66 ± 0.08 × Mg/Casw0.27±0.06 × e(0.114±0.02 × BWT) and our favored linear temperature calibration is Mg/Ca = (1.21 ± 0.04 + 0.12 ± 0.004 × BWT (bottom water temperature)) × (Mg/Casw-0.003±0.02) (stated errors are 2 s.e.). The equations are obtained by comparing O. umbonatus Mg/Ca for a Paleocene-Eocene section from Ocean Drilling Program (ODP) Site 690 (Weddell Sea) to δ18O temperatures, calculated assuming ice-free conditions during this peak warmth period of the Cenozoic. This procedure suggests negligible effect of Mg/Casw on the Mg distribution coefficient (DMg). Application of the new equations to the Site 806 record leads to the suggestion that global ice volume was greater than today after the Middle Miocene Climate Transition (~14 Ma). ODP Site 806 bottom waters cooled and freshened as the Pacific zonal sea surface temperature gradient increased, and climate cooled through the Pliocene, prior to the Plio-Pleistocene glaciation of the Northern Hemisphere. The records indicate a decoupling of deep water temperatures and global ice volume, demonstrating the importance of thresholds in the evolution of the Antarctic ice sheet.

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.

Southern high-latitude terrestrial climate change during the Paleocene-Eocene derived from a marine pollen record (ODP Site 1172, East Tasman Plateau)

NASA Astrophysics Data System (ADS)

Contreras, L.; Pross, J.; Bijl, P. K.; O'Hara, R. B.; Raine, J. I.; Sluijs, A.; Brinkhuis, H.

2014-01-01

Reconstructing the early Paleogene climate dynamics of terrestrial settings in the high southern latitudes is important to assess the role of high-latitude physical and biogeochemical processes in the global climate system. However, whereas a number of high-quality Paleogene climate records has become available for the marine realm of the high southern latitudes over the recent past, the long-term evolution of coeval terrestrial climates and ecosystems is yet poorly known. We here explore the climate and vegetation dynamics on Tasmania from the middle Paleocene to the early Eocene (60.7-54.2 Ma) based on a sporomorph record from Ocean Drilling Program (ODP) Site 1172 on the East Tasman Plateau. Our results show that three distinctly different vegetation types thrived on Tasmania under a high-precipitation regime during the middle Paleocene to early Eocene, with each type representing different temperature conditions: (i) warm-temperate forests dominated by gymnosperms that were dominant during the middle and late Paleocene; (ii) cool-temperate forests dominated by southern beech (Nothofagus) and araucarians across the middle/late Paleocene transition interval (~59.5 to ~59.0 Ma); and (iii) paratropical forests rich in ferns that were established during and in the wake of the Paleocene-Eocene Thermal Maximum (PETM). The transient establishment of cool-temperate forests lacking any frost-sensitive elements (i.e., palms and cycads) across the middle/late Paleocene transition interval indicates markedly cooler conditions, with the occurrence of frosts in winter, on Tasmania during that time. The integration of our sporomorph data with previously published TEX86-based sea-surface temperatures from ODP Site 1172 documents that the vegetation dynamics on Tasmania were closely linked with the temperature evolution in the Tasman sector of the Southwest Pacific region. Moreover, the comparison of our season-specific climate estimates for the sporomorph assemblages from ODP Site 1172 with the TEX86L- and TEX86H-based temperature data suggests a warm-season bias of both calibrations for the early Paleogene of the high southern latitudes.

Southern high-latitude terrestrial climate change during the Palaeocene-Eocene derived from a marine pollen record (ODP Site 1172, East Tasman Plateau)

NASA Astrophysics Data System (ADS)

Contreras, L.; Pross, J.; Bijl, P. K.; O'Hara, R. B.; Raine, J. I.; Sluijs, A.; Brinkhuis, H.

2014-07-01

Reconstructing the early Palaeogene climate dynamics of terrestrial settings in the high southern latitudes is important to assess the role of high-latitude physical and biogeochemical processes in the global climate system. However, whereas a number of high-quality Palaeogene climate records has become available for the marine realm of the high southern latitudes over the recent past, the long-term evolution of coeval terrestrial climates and ecosystems is yet poorly known. We here explore the climate and vegetation dynamics on Tasmania from the middle Palaeocene to the early Eocene (60.7-54.2 Ma) based on a sporomorph record from Ocean Drilling Program (ODP) Site 1172 on the East Tasman Plateau. Our results show that three distinctly different vegetation types thrived on Tasmania under a high-precipitation regime during the middle Palaeocene to early Eocene, with each type representing different temperature conditions: (i) warm-temperate forests dominated by gymnosperms that were dominant during the middle and late Palaeocene (excluding the middle/late Palaeocene transition); (ii) cool-temperate forests dominated by southern beech (Nothofagus) and araucarians that transiently prevailed across the middle/late Palaeocene transition interval (~ 59.5 to ~ 59.0 Ma); and (iii) paratropical forests rich in ferns that were established during and in the wake of the Palaeocene-Eocene Thermal Maximum (PETM). The transient establishment of cool-temperate forests lacking any frost-sensitive elements (i.e. palms and cycads) across the middle/late Palaeocene transition interval indicates markedly cooler conditions, with the occurrence of frosts in winter, on Tasmania during that time. The integration of our sporomorph data with previously published TEX86-based sea-surface temperatures from ODP Site 1172 documents that the vegetation dynamics on Tasmania were closely linked with the temperature evolution in the Tasman sector of the Southwest Pacific region. Moreover, the comparison of our season-specific climate estimates for the sporomorph assemblages from ODP Site 1172 with the TEX86L- and TEX86H-based temperature data suggests a warm bias of both calibrations for the early Palaeogene of the high southern latitudes.

Changing surface water conditions for the last 500 ka in the Southeast Atlantic: Implications for variable influences of Agulhas leakage and Benguela upwelling

NASA Astrophysics Data System (ADS)

Petrick, Benjamin F.; McClymont, Erin L.; Marret, Fabienne; van der Meer, Marcel T. J.

2015-09-01

The Southeast Atlantic Ocean is an important component of global ocean circulation, as it includes heat and salt transfer into the Atlantic through the Agulhas leakage as well as the highly productive Benguela upwelling system. Here we reconstruct sea surface temperatures (SSTs) from Ocean Drilling Program (ODP) Site 1087 in the Southeast Atlantic to investigate surface ocean circulation patterns during the late Pleistocene (0-500 ka). The UK'37 index and dinoflagellate cyst assemblages are used to reconstruct SSTs, δDalkenone is used to reconstruct changes in sea surface salinity, and mass accumulation rates of alkenones and chlorine pigments are quantified to detect changing marine export productivity. The greatest amplitude of SST warming precedes decreases in benthic δ18O and therefore occurs early in the transition from glacials to interglacials. The δDalkenone, as a salinity indicator, increases before SSTs, suggesting that the pattern of Agulhas leakage is more complex than suggested by SST proxies. Marine isotope stage (MIS) 10 shows an anomalous pattern: it is marked by a pronounced increase in chlorine concentration, which may be related to enhanced/expanded Benguela upwelling reaching the core site. We find no evidence of an absence of Agulhas leakage throughout the record, suggesting that there is no Agulhas cutoff even during MIS 10. Finally, the ODP Site 1087 record shows an increasing strength of Agulhas leakage towards the present day, which may have impacted the intensity of the Atlantic meridional overturning circulation. As a result, the new analyses from ODP Site 1087 demonstrate a complex interaction between influences of the Benguela upwelling and the Agulhas leakage through the late Pleistocene, which are inferred here to reflect changing circulation patterns in the Southern Ocean and in the atmosphere.

Combined in-depth, 3D, en face imaging of the optic disc, optic disc pits and optic disc pit maculopathy using swept-source megahertz OCT at 1050 nm.

PubMed

Maertz, Josef; Kolb, Jan Philip; Klein, Thomas; Mohler, Kathrin J; Eibl, Matthias; Wieser, Wolfgang; Huber, Robert; Priglinger, Siegfried; Wolf, Armin

2018-02-01

To demonstrate papillary imaging of eyes with optic disc pits (ODP) or optic disc pit associated maculopathy (ODP-M) with ultrahigh-speed swept-source optical coherence tomography (SS-OCT) at 1.68 million A-scans/s. To generate 3D-renderings of the papillary area with 3D volume-reconstructions of the ODP and highly resolved en face images from a single densely-sampled megahertz-OCT (MHz-OCT) dataset for investigation of ODP-characteristics. A 1.68 MHz-prototype SS-MHz-OCT system at 1050 nm based on a Fourier-domain mode-locked laser was employed to acquire high-definition, 3D datasets with a dense sampling of 1600 × 1600 A-scans over a 45° field of view. Six eyes with ODPs, and two further eyes with glaucomatous alteration or without ocular pathology are presented. 3D-rendering of the deep papillary structures, virtual 3D-reconstructions of the ODPs and depth resolved isotropic en face images were generated using semiautomatic segmentation. 3D-rendering and en face imaging of the optic disc, ODPs and ODP associated pathologies showed a broad spectrum regarding ODP characteristics. Between individuals the shape of the ODP and the appending pathologies varied considerably. MHz-OCT en face imaging generates distinct top-view images of ODPs and ODP-M. MHz-OCT generates high resolution images of retinal pathologies associated with ODP-M and allows visualizing ODPs with depths of up to 2.7 mm. Different patterns of ODPs can be visualized in patients for the first time using 3D-reconstructions and co-registered high-definition en face images extracted from a single densely sampled 1050 nm megahertz-OCT (MHz-OCT) dataset. As the immediate vicinity to the SAS and the site of intrapapillary proliferation is located at the bottom of the ODP it is crucial to image the complete structure and the whole depth of ODPs. Especially in very deep pits, where non-swept-source OCT fails to reach the bottom, conventional swept-source devices and the MHz-OCT alike are feasible and beneficial methods to examine deep details of optic disc pathologies, while the MHz-OCT bears the advantage of an essentially swifter imaging process.

Changes in Equatorial Atlantic Ocean Thermohaline Circulation Across the Mid-Pleistocene Transition

NASA Astrophysics Data System (ADS)

Yehudai, M.; Kim, J.; Seguí, M. J.; Goldstein, S. L.; Pena, L. D.; Haynes, L.; Hoenisch, B.; Farmer, J. R.; Ford, H. L.; Raymo, M. E.; Bickert, T.

2016-12-01

The Mid-Pleistocene Transition (MPT) marked a change in the duration of glacial-interglacial cycles from 41 to 100kyr between 1.3-0.7 Ma. A recent study (Pena and Goldstein, Science, 2014) from the Southern Atlantic Ocean found evidence for major disruptions in the global thermohaline circulation (THC) between MIS 25-21 ( 950-850ka), which may have triggered intensified glacial periods and the onset of the 100 kyr cycles. We report new Nd isotope data on Fe-Mn oxide encrusted foraminifera and fish debris from ODP Site 926 (3.719N, 42.908W, 3598m) between 1.2-0.4 Ma, in order to evaluate changes in the THC in the equatorial Atlantic, through comparison with North and South Atlantic sites. The ODP 926 ɛNd values fall in-between those in the North Atlantic (DSDP 607) and South Atlantic (ODP 1088 and 1090) throughout the studied interval, consistent with mixing between northern and southern end-members, and supporting the interpretation that the data represent the THC signal at this site. Pre-MPT data show smaller glacial-interglacial differences compared to the greater post-MPT glacial-interglacial variability. As Pena and Goldstein (2014) observed in the South Atlantic, during MIS 23 at 900 ka, ɛNd values do not shift significantly toward North Atlantic more negative values, consistent with a weak THC through this critical weak interglacial. Comparing ODP 926 and DSDP 607 data, ɛNd values converge during most interglacial peaks (excepting MIS 23) and diverge otherwise. This observation indicates that northern-sourced water masses dominate the site during peak interglacials, and confirms that the THC has been strongest during peak interglacials throughout the studied interval. Otherwise, diverging ɛNd values indicate a stronger southern-source signal and weaker northern-source signal at the ODP 926 site. This confirms that there was an active but variable THC system before, during, and after the MPT, with stronger deep water export from the North Atlantic during interglacials.

Late Miocene - Pliocene Evolution of the Pacific Warm Pool and Cold Tongue: Implications for El Niño

NASA Astrophysics Data System (ADS)

Zhang, Y.; Pagani, M.

2011-12-01

The Western Pacific Warm Pool of the tropical Pacific Ocean retains the largest and warmest sea surface water body on Earth, while the eastern equatorial Pacific is characterized by strong upwelling of cold, nutrient-rich deep waters, termed the Pacific cold tongue. Evolution of the Pacific warm pool and cold tongue are important because they control the circum-Pacific climate and impact the globe via El Niño - Southern Oscillation (ENSO) teleconnections. Sea surface temperature (SST) reconstructions using a single site from the warm pool (ODP 806) and two sites from the cold tongue (ODP 846, 847) suggest that the temperature of the warm pool was "stable" throughout the Plio-Pleistocene, whereas the cold tongue was much warmer in the Pliocene and subsequently cooled. The absence of an east-west Pacific temperature gradient during the early Pliocene is the basis for the "permanent El Niño" hypothesis. However, annually-resolved fossil coral and evaporite records found 3-7 years climate variability during the Pliocene warm period and late Miocene, challenging a "permanent" or invariant climate state. Here we present a multi-proxy (TEX86, UK37, Mg/Ca), multi-site reconstruction of the late Miocene - Pliocene (ca. 12 Ma - 3 Ma) SST in the Pacific warm pool (ODP 806, ODP 769 in the Sulu Sea, ODP 1143 in the South China Sea) and the cold tongue (ODP 850, 849, 846). Our results show that the cold tongue was even warmer in the late Miocene than the Pliocene, and that the warm pool cooled 2-3°C from the late Miocene into the Pliocene - in contrast to the invariant character previously assumed. Temperature comparison between different sites suggests that the warm pool may have expanded in size in the late Miocene. Although eastern and western ends of the tropical Pacific were warmer, a persistent, but low east-west temperature gradient (~3°C) is apparent. This agrees with recent studies which have shown ENSO-related frequency of climate change in the late Miocene and early Pliocene.

The Blake Nose Cretaceous-Paleogene (Florida Atlantic margin, ODP Leg 171B): an exemplar record of the Maastrichtian-Danian transition

USGS Publications Warehouse

Bellier, J.-P.; Marca, S.; Norris, R.D.; Kroon, D.; Klaus, A.; Alexander, I.T.; Bardot, L.P.; Barker, C.E.; Blome, C.D.; Clarke, L.J.; Erbacher, J.; Faul, K.L.; Holmes, M.A.; Huber, B.T.; Katz, M.E.; MacLeod, K.G.; Martinez-Ruiz, F. C.; Mita, I.; Nakai, M.; Ogg, James G.; Pak, D.K.; Pletsch, T.K.; ,; Shackleton, N.J.; Smit, J.; Ussler, W.; Watkins, D.K.; Widmark, J.; Wilson, P.A.

1997-01-01

During ODP Leg 171B, devoted to the analysis of the Blake Plateau margin in front of Florida, 16 holes have been drilled in 5 distinct sites. The sites have documented a sedimentary succession ranging in age from Aptian to Eocene. Emphasis has been put on critical periods, comprising the Paleocene-Eocene transition, the Cretaceous-Tertiary boundary which has been cored in excellent conditions, the middle Maastrichtian extinctions and the Albian anoxic episodes.

Detailed view into the dynamics of the Late Miocene glaciation episode that accompanied terrestrial evolution

NASA Astrophysics Data System (ADS)

Tzanova, A.; Herbert, T.; Lawrence, K. T.; Peterson, L.; Kelly, C. S.

2015-12-01

We focus on the period of ~ 9 - 5 Ma when an episode of notably cool temperatures corresponds to evidence of high latitude Northern Hemisphere glaciation and mid-latitude terrestrial evolution. Alkenone-based sea surface temperatures (SST) from six globally distributed sites: ODP Sites 907 and 982 in the North Atlantic, ODP Site 1088 in the South Atlantic and ODP Sites 883, 884 and 887 in the North Pacific, and the Monte dei Corvi marine section in the Mediterranean unequivocally establish a dramatic, Late Miocene cold episode that persisted over approximately 2.5 Myr. In this work we establish the timing and synchronization of temperature decrease as well as rebound at orbital timescales. All sites were notably warmer than their modern annual average at ~9 Ma and exhibit sustained cooling beginning at ~8 Ma. SSTs rebound close to ~5.9 Ma at most locations suggesting that the cooling trend that began in the Late Miocene slowed down or even reversed in some locations in the Pliocene. The newly reconstructed SSTs highlight the role of cooling and an increase in equator to pole temperature gradients in terrestrial evolution at this pivotal time.

Astrochronology of a Late Oligocene to Early Miocene Magnetostratigraphy from the Northwest Atlantic

NASA Astrophysics Data System (ADS)

van Peer, T. E.; Xuan, C.; Liebrand, D.; Lippert, P. C.; Wilson, P. A.

2016-12-01

The Oligocene-Miocene Boundary is defined by the geomagnetic polarity reversal C6Cn.2n/C6Cn.2r with an astronomically tuned age of 23 Ma. For late Oligocene to early Miocene reversals, only a few records (mainly from the equatorial Pacific and South Atlantic) integrate magneto- and cyclo-stratigraphy with astronomical tuning. Reversal ages acquired from these records show differences up to 100 kyr. We report new astronomically tuned ages for reversals between 21-26.5 Ma, based on integrated palaeomagnetic and X-Ray Fluorescence (XRF) data from rapidly accumulated drift sediments (mean sedimentation rate of 2.5 cm/kyr) at Integrated Ocean Drilling Program (IODP) Site U1406 (northwest Atlantic). The natural remanence preserved in the sediments is relatively weak (especially at high demagnetisation steps) and prone to influence from measurement noise. We introduce an optimisation protocol to improve the estimation of component directions used to define the reversals. For each 1-cm interval measurement, the protocol searches for the combination of a fixed number of steps of demagnetisation data that minimises the maximum angular deviation, statistically excluding the noisy measurement steps. For the tuning, we use the logarithm of the calcium over potassium ratio ln(Ca/K) from XRF core scanning data, a proxy of carbonate content in the sediment. Spectral and wavelet analyses of the 140-m long ln(Ca/K) record highlight dominant obliquity (including the 178 and 1200 kyr modulation) and additional eccentricity forcing. Supported by preliminary stable isotope analysis on benthic foraminifera, we tuned ln(Ca/K) minima to obliquity minima and eccentricity maxima. The resulting age model yield new independent ages for all reversals between C6Ar/C6AAn to C8r/C9n. Our results are generally consistent (within an obliquity cycle) with the Ocean Drilling Program (ODP) Site 1090 age model [Billups et al., 2004], but deviate up to 80 kyr relative to ODP Site 1218 [Pälike et al., 2006] and ATNTS2004 [Lourens et al., 2004] age models. The concurrent high-fidelity reversal ages from ODP Site 1090 and IODP Site U1406 reconcile discrepancies in the early Miocene GPTS, and provide improved temporal constraints, which are critical to the study of palaeomagnetic and environmental changes of this time interval.

Global Sea Surface Temperature and Ecosystem Change Across the Mid-Miocene Climatic Optimum

NASA Astrophysics Data System (ADS)

Veenstra, T. J. T.; Bakker, V. B.; Sangiorgi, F.; Peterse, F.; Schouten, S.; Sluijs, A.

2016-12-01

Even though the term Mid-Miocene Climatic Optimum (MMCO; ca. 17 to 14 Ma) has been widely used in the literature since the early 1990's, almost no early-middle Miocene sea surface temperature (SST) proxy records have been published that support climate warming across its onset. Benthic (and diagenetically altered planktic) foram δ18O records show a decrease, suggesting (deep) ocean warming and/or Antarctic ice sheet melting. However, reliable absolute SST proxy records are absent from the tropics and very scarce in temperate and polar regions. This leaves the question if the warmth of the MMCO was truly global and how its onset relates to the widely recorded positive (Monterey) carbon isotope excursion and volcanism. Finally, it remains uncertain how marine ecosystems responded to this hypothesized warming. We present organic biomarker SST proxy records (Uk'37 and TEX86) spanning the MMCO for several locations in the Atlantic and Pacific Ocean along a pole-to-pole transect, including Ocean Drilling Program Site 959 in the eastern Tropical Atlantic, ODP Site 643 in the Norwegian Sea, ODP Site 1007 on the Great Bahama Bank and Integrated Ocean Drilling Program Site U1352 off New Zealand. Additionally, we use marine palynology (mostly dinoflagellate cysts) to assess ecosystem change at these locations. The resulting spatial reconstruction of SST change shows that Middle Miocene warming was global. Nevertheless, the records also show distinct regional variability, including relatively large warming in the Norwegian Sea and a damped signal in the southern hemisphere, suggesting pronounced changes in ocean circulation. The onset of the MMCO was marked by prominent changes in ecological and depositional setting at the studied sites, likely also related to ocean circulation changes.

Late Oligocene to early Miocene geochronology and paleoceanography from the subantarctic South Atlantic

NASA Astrophysics Data System (ADS)

Billups, K.; Channell, J. E. T.; Zachos, J.

2002-01-01

At Ocean Drilling Program (ODP) Site 1090 on the Agulhas Ridge (subantarctic South Atlantic) benthic foraminiferal stable isotope records span the late Oligocene through the early Miocene (25-16 Ma) at a temporal resolution of ~10 kyr. In the same time interval a magnetic polarity stratigraphy can be unequivocally correlated to the geomagnetic polarity timescale (GPTS), thereby providing secure correlation of the isotope record to the GPTS. On the basis of the isotope-magnetostratigraphic correlation we provide refined age calibration of established oxygen isotope events Mi1 through Mi2 as well as several other distinctive isotope events. Our data suggest that the δ18O maximum commonly associated with the Oligocene/Miocene (O/M) boundary falls within C6Cn.2r (23.86 Ma). The δ13C maximum coincides, within the temporal resolution of our record, with C6Cn.2n/r boundary and hence to the O/M boundary. Comparison of the stable isotope record from ODP Site 1090 to the orbitally tuned stable isotope record from ODP Site 929 across the O/M boundary shows that variability in the two records is very similar and can be correlated at and below the O/M boundary. Site 1090 stable isotope records also provide the first deep Southern Ocean end-member for reconstructions of circulation patterns and late Oligocene to early Miocene climate change. Comparison to previously published records suggests that basin to basin carbon isotope gradients were small or nonexistent and are inconclusive with respect to the direction of deep water flow. Oxygen isotope gradients between sites suggest that the deep Southern Ocean was cold in comparison to the North Atlantic, Indian, and the Pacific Oceans. Dominance of cold Southern Component Deep Water at Site 1090, at least until 17 Ma, suggests that relatively cold circumpolar climatic conditions prevailed during the late Oligocene and early Miocene. We believe that a relatively cold Southern Ocean reflects unrestricted circumpolar flow through the Drake Passage in agreement with bathymetric reconstructions.

Abrupt turnover in calcareous-nannoplankton assemblages across the Paleocene/Eocene Thermal Maximum: implications for surface-water oligotrophy over the Kerguelen Plateau, Southern Indian Ocean

USGS Publications Warehouse

Jiang, Shijun; Wise, Sherwood W.

2007-01-01

Ocean Drilling Program (ODP) Core Section 183-1135A-25R-4 from the Kerguelen Plateau in the Indian Ocean sector of the Southern Ocean represents only the second complete, expanded sequence through the Paleocene/Eocene Thermal Maximum (PETM; ~55 Ma) recovered from Antarctic waters. Calcareous nannoplankton at this site underwent an abrupt, fundamental turnover across the PETM as defined by a carbon isotope excursion. Although Chiasmolithus, Discoaster, and Fasciculithus exponentially increase in abundance at the onset, the former abruptly drops but then rapidly recovers, whereas the latter two taxa show opposite trends due to surface-water oligotrophy. These observations confirm previous results from ODP Site 690 on Maud Rise. The elevated pCO2 that accompanied the PETM caused a shoaling of the lysocline and carbonate compensation depth, leading to intensive dissolution of susceptible holococcoliths and poor preservation of the assemblages. Similarities and contrasts between the results of this study and previous work from open-ocean sites and shelf margins further demonstrate that the response to the PETM was consistent in open-ocean environments, but could be localized on continental shelves where nutrient regimes depend on the local geologic setting and oceanographic conditions.

Ocean Drilling Program Contributions to the Understanding of the Deep Subsurface Biosphere

NASA Astrophysics Data System (ADS)

Fisk, M. R.

2003-12-01

Tantalizing evidence for microbes in oceanic basalts has been reported for a few decades, but it was from rocks cored on Ocean Drilling Program (ODP) Leg 148 in 1993 that the first clear-cut evidence of microbial invasion of ocean basalts was obtained. (Work on ODP legs, starting with Leg 112 in 1986, had already revealed the presence of significant microbial biomass in sediments.) In 1997 ODP created the Deep Biosphere Program Planning Group to promote the investigation of the microbiology of the ocean crust. In 1999 ODP built a microbiology lab on the JOIDES Resolution, and used the lab that year (Legs 185 and 187) to test the amount of microbial contamination introduced into rocks during drilling and to establish cultures from cored basalts. These experiments have been repeated on several legs since then. The development of CORKs has permitted long-term sampling of subseafloor fluids, and microorganisms have been recovered from CORKed holes. Thus, ODP made it possible for the scientific community to address major questions about the biology of the igneous crust, such as, (1) What microbes are present? (2) How abundant are they? (3) How are they distributed? DNA from basalts and subseafloor fluids reveal what types of organisms are present. Cell abundance and biomass have been estimated based on cell counts and on organic content of basalts. Surveys of basalts in DSDP/ODP repositories indicate that microorganisms are ubiquitous in the igneous crust. Microorganisms are found in rocks that are close to 100° C. They are found as deep as 1500 m below the sea floor, and in rocks as young as a few years and as old as 170 million years. Because of the vast size of the habitat, microorganism, even if present in small numbers, could be a significant fraction of the Earth's biomass. In a short time ODP contributed to advances in our understanding of the oceanic subsurface biosphere. Answers to other significant questions such as: (1) How do the microorganisms live?, (2) What impact do subsurface microorganisms have on the surface biosphere? (3) And, what roles do the subsurface biosphere play in element cycling? will be answered by future drilling. The International Ocean Drilling Program (IODP) is in the enviable position of providing support to address these key questions about the Earth's subsurface biosphere.

Late Paleocene-middle Eocene benthic foraminifera on a Pacific seamount (Allison Guyot, ODP Site 865): Greenhouse climate and superimposed hyperthermal events

NASA Astrophysics Data System (ADS)

Arreguín-Rodríguez, Gabriela J.; Alegret, Laia; Thomas, Ellen

2016-03-01

We investigated the response of late Paleocene-middle Eocene (~60-37.5 Ma) benthic foraminiferal assemblages to long-term climate change and hyperthermal events including the Paleocene-Eocene Thermal Maximum (PETM) at Ocean Drilling Program (ODP) Site 865 on Allison Guyot, a seamount in the Mid-Pacific Mountains. Seamounts are isolated deep-sea environments where enhanced current systems interrupt bentho-pelagic coupling, and fossil assemblages from such settings have been little evaluated. Assemblages at Site 865 are diverse and dominated by cylindrical calcareous taxa with complex apertures, an extinct group which probably lived infaunally. Dominance of an infaunal morphogroup is unexpected in a highly oligotrophic setting, but these forms may have been shallow infaunal suspension feeders, which were ecologically successful on the current-swept seamount. The magnitude of the PETM extinction at Site 865 was similar to other sites globally, but lower diversity postextinction faunas at this location were affected by ocean acidification as well as changes in current regime, which might have led to increased nutrient supply through trophic focusing. A minor hyperthermal saw less severe effects of changes in current regime, with no evidence for carbonate dissolution. Although the relative abundance of infaunal benthic foraminifera has been used as a proxy for surface productivity through bentho-pelagic coupling, we argue that this proxy can be used only in the absence of changes in carbonate saturation and current-driven biophysical linking.

Orbitally resolved records of Oligocene ice-sheet dynamics and deep-water chemistry from ODP Site 689 (Maud Rise, Weddell Sea)

NASA Astrophysics Data System (ADS)

Bohaty, Steven M.; Huck, Claire E.; Liebrand, Diederik; Röhl, Ursula; Wilson, Paul; van de Flierdt, Tina; Pälike, Heiko

2016-04-01

The early stages of the modern 'Icehouse' climate state first developed in the Oligocene following rapid global cooling and the onset of Antarctic glaciation at the Eocene-Oligocene Transition (34 Ma). However, the size and stability of the early Antarctic ice sheets that existed during the Oligocene under atmospheric CO2 levels higher than present day are poorly known. Here we report on an ongoing investigation of Oligocene (hemi)pelagic drillcores recovered at Ocean Drilling Program (ODP) Site 689, drilled on Maud Rise in the eastern Weddell Sea in late 1980s (Leg 113). Shipboard physical properties data were not routinely collected from pre-Quaternary cores at this site, and the lack of continuous composite sections and supporting data has previously been a considerable hindrance to high-resolution paleoceanographic studies. New high-resolution XRF scanning, discrete magnetic susceptibility, and benthic foraminiferal stable isotope records were collected from the upper Eocene-upper Oligocene interval of ODP Sites 689. The XRF datasets allow compositing of Holes 689B and 689D, which fortuitously contain offset cores throughout the sequence. Although condensed in two intervals, Site 689 contains a complete ~12-Myr record spanning Chron C17n.1n to Chron C8n.1n (~37 to 25 Ma). The composited records from Sites 689 exhibit prominent orbital-scale cyclicity in XRF-derived iron/calcium ratios, enabling development of an astronomical age model and detailed reconstruction of carbonate dissolution intensity of South Atlantic deep waters. These composited and well-dated records from Site 689 will, for the first-time, provide an Oligocene pelagic reference section for the Southern Ocean and serve as stratigraphic stepping stone between proximal Antarctic shelf records and high-resolution proxy records from lower latitude locations. Further development of high-resolution benthic foraminiferal and detrital neodymium isotope records at Site 689 will address the timing and frequency of East Antarctic ice-sheet advance and retreat events during cool intervals of the mid Oligocene and the onset of warming in the latest Oligocene. These data will both inform and test model results of ice-sheet behaviour and stability during different climatic phases of the Oligocene.

Variations in the Nd isotope composition of Late Miocene to Early Pliocene glacially derived sediments in Prydz Bay, East Antarctica

NASA Astrophysics Data System (ADS)

Mabson, M.; Pierce, E. L.; Dale, C. L.; Williams, T.; Hemming, S. R.; van de Flierdt, T.; Cook, C.; Goldstein, S. L.

2010-12-01

Michelle Mabson (Howard University), Elizabeth Pierce (Lamont-Doherty Earth Observatory, Columbia University), Cathleen Doherty (Lamont-Doherty Earth Observatory, Columbia University), Trevor Williams (Lamont-Doherty Earth Observatory), Sidney Hemming (Lamont-Doherty Earth Observatory), Tina van de Flierdt (Imperial College London), Carys Cook (Imperial College London), Steve Goldstein (Lamont-Doherty Earth Observatory) Since initiation of major ice sheets on Antarctica at about 34 Ma, Antarctica has been a major player in global climate change. Understanding the response of the East Antarctic Ice Sheet to major climate changes through the Cenozoic has fundamental importance to both Earth Sciences and Society. Previous study of Nd isotope composition of sediments at Ocean Drilling Program (ODP) Site 1166 within Prydz Bay found evidence for variations of the Nd isotope composition between -15 to -30 epsilon units through this pre-glacial to glacial record (van de Flierdt et al., 2008, GRL). The Nd isotope composition of sediments provides an estimate for the average continental crust formation age of the sources. The sources around Prydz Bay have a wide range of formation ages, from Archean to Phanerozoic, so the areas which were being preferentially eroded can be inferred. This study seeks to contribute evidence for the local variations in provenance of sediments by extending the record of Nd isotope variations to ODP Site 739 in Prydz Bay. ODP Site 1165 has an unconformity that spans ~30-3 Ma. This part of the record is much more complete in ODP site 739, located about 200 km from the coast of Prydz Bay, probably more protected from ice stream erosion in the Prydz Channel. Because of its location we can conclude that the sediment deposited into this area is derived from the Lambert Glacier, and thus the variations in epsilon Nd will allow testing whether changes in the extent of this ice stream could lead to variations in the provenance of sediment carried by this ice. Recently Williams et al. (2010, EPSL) published evidence for dramatic changes in the sources of glacially derived sediments at ODP Site 1165, further offshore from Prydz Bay, at 7, 4.8 and 3.5 Ma. Their interpretation was based on the Ar-Ar ages of detrital hornblende grains, but samples taken across the 4.8 Ma event also showed an intriguing variation of the Nd isotope composition. The older part of the event includes a significant fraction of exotic Ar-Ar ages, but with epsilon Nd similar to the background values, while the younger part of the event shows a significant decrease in epsilon Nd but Ar-Ar of local origin. The specific goal of this study is to test the hypothesis that the shift to lower epsilon Nd in the 4.8 Ma ice rafting event is due to dynamical changes in the Prydz Bay sector of the East Antarctic ice sheet. Alternatively, the Lambert glacier may have retreated far enough to allow other sources in this sector to dominate the sediment composition in core 1165.

Ocean Drilling Program: Information Services: Database Services

Science.gov Websites

Available Examples of Data Core Photos Logging Database (LDEO-BRG) RIDGE Petrological Database (LDEO from postcruise research All ODP and DSDP core photos All ODP data are available online through Janus proprietary for a period of one year after the end of a cruise and are available only to the participating

Interglacial/glacial changes in coccolith-rich deposition in the SW Pacific Ocean: An analogue for a warmer world?

NASA Astrophysics Data System (ADS)

Duncan, Bella; Carter, Lionel; Dunbar, Gavin; Bostock, Helen; Neil, Helen; Scott, George; Hayward, Bruce W.; Sabaa, Ashwaq

2016-09-01

Satellite observations of middle to high latitudes show that modern ocean warming is accompanied by increased frequency and poleward expansion of coccolithophore blooms. However, the outcomes of such events and their causal processes are unclear. In this study, marine sediment cores are used to investigate past coccolithophore production north and south of the Subtropical Front. Calcareous pelagites from subtropical waters off northernmost New Zealand (site P71) and from subantarctic waters on Campbell Plateau (Ocean Drilling Program [ODP] site 1120C) record marked changes in pelagite deposition. At both locations, foraminiferal-rich sediments dominate glacial periods whereas coccolith-rich sediments characterise specific interglacial periods. Sediment grain size has been used to determine relative abundances of coccoliths and foraminifers. Results show coccoliths prevailed around certain Marine Isotope Stage (MIS) transitions, at MIS 7b/a and MIS 2/1 at P71, and at MIS 6/5e at ODP 1120C. Palaeo-environmental proxies suggest that coccolithophore production and deposition at P71 reflect enhanced nutrient availability associated with intense winter mixing in the subtropical Tasman Sea. An increased inflow of that warm, micronutrient-bearing subtropical water in concert with upper ocean thermal stratification in late spring/summer, led to peak phytoplankton production. At ODP 1120C during MIS 6/5e, an increased inflow of subtropical water, warm sea surface temperatures and a thermally stratified upper ocean also favoured coccolithophore production. These palaeo-environmental reconstructions together with model simulations suggest that (i) future subtropical coccolithophore production at P71 is unlikely to reach abundances recorded during MIS 7b/a but (ii) future subantarctic production is likely to dominate sedimentation over Campbell Plateau as modern conditions trend towards those prevalent during MIS 5e.

High-resolution palaeomagnetic records of the Laschamp geomagnetic excursion from ODP Sites 1061 and 1062

NASA Astrophysics Data System (ADS)

Bourne, M. D.; Henderson, G. M.; Thomas, A. L.; Mac Niocaill, C.

2012-12-01

The Laschamp geomagnetic excursion (~41 ka) was a brief global deviation in geomagnetic field behaviour from that expected during normal secular variation. Previously published records suggest rapid changes in field direction and a concurrent substantial decrease in field intensity. We present here high-resolution palaeomagnetic records of the Laschamp excursion obtained from two Ocean Drilling Program (ODP) Sites 1061 and 1062 on the Blake-Bahama Outer Ridge (ODP Leg 172) and compare this record with previously published records of the Blake and Iceland Basin Excursions. Relatively high sedimentation rates (>10 cm kyr-1) at these locations allow the determination of transitional field behaviour during the excursion. Rather than assuming a constant sedimentation rate between assigned age tie-points, we employ measurements of 230Thxs concentration in the sediment to assess variations in the sedimentation rates through the core sections of interest. This allows us to better determine the temporal behaviour of the Laschamp excursion with greater accuracy and known uncertainty. The Laschamp excursion at this location appears to be much shorter in duration than the Blake and Iceland Basin excursions. Palaeomagnetic measurements of discrete samples from four cores reveal a single excursional feature, across an interval of 30 cm, associated with a broader palaeointensity low. The excursion is characterised by rapid transitions (less than 500 years) between a stable normal polarity and a partially-reversed, polarity. Peaks in inclination either side of the directional excursion indicate periods of time when the local field is dominated by vertical flux patches. Similar behaviour has been observed in records of the Iceland Basin Excursion from the same region. The palaeointensity record is in good agreement between the two sites. The palaeointensity record shows two minima, where the second dip in intensity is associated with a more limited directional deviation. Similar field intensity behaviour has been observed during the Blake excursion suggesting that the geomagnetic field stability may be reduced for relatively long durations, potentially up to tens of thousands of years.

Nankai Stress History and Implications for an Overpressured Decollement

NASA Astrophysics Data System (ADS)

Moran, K.; O'Regan, M.

2005-12-01

The Nankai Trough, formed from the subduction of the Shikoku Basin beneath the island arc of southwestern Japan, is a relatively young accretionary complex converging at a rate of ~4 cm/yr [Shipboard Scientific Party, 2001a]. The region was studied during the Deep Sea Drilling Project and on three Ocean Drilling Program (ODP) Legs-131, 190 and 196. Three sites visited during these Legs form a single cross-margin transect (dubbed the Muroto Transect) that traverses the leading edge of the Nankai accretionary prism, from seaward of the deformation front at Site 1173, to close to the deformation front (Site 1174), and landward to the first frontal thrust (Site 808). The decollement, which forms the major boundary between the converging plates, occurs within the Lower Shikoku Basin stratigraphic unit. The ODP sites were drilled and cored to depths below the decollement (Sites 808 and 1174) and the proto-decollement (Site 1173). Here we present consolidation test results [Moran et al., 1993] that are consistent with porosity-depth functions from core and log measurements for the Lower Shikoku Basin sediments, assuming that the decollement is an overpressured seal. At 1173, where a true decollement has not yet formed, moderate fluid overpressures occur that can be fully attributed to high turbiditic sedimentation rates. Forward modeling of this site into the deformation front over a period of ~300 ky shows that the present 1173 porosity-depth function matches the porosity-depth function at 1174. These results suggest that the young decollement on the Muroto Transect at the deformation front and landward is highly overpressured and forms a seal to sediments below that can be classically modeled as a one-dimensional consolidation system.

ODP Site 1063 (Bermuda Rise) revisited: Oxygen isotopes, excursions and paleointensity in the Brunhes Chron

NASA Astrophysics Data System (ADS)

Channell, J. E. T.; Hodell, D. A.; Curtis, J. H.

2012-02-01

An age model for the Brunhes Chron of Ocean Drilling Program (ODP) Site 1063 (Bermuda Rise) is constructed by tandem correlation of oxygen isotope and relative paleointensity data to calibrated reference templates. Four intervals in the Brunhes Chron where paleomagnetic inclinations are negative for both u-channel samples and discrete samples are correlated to the following magnetic excursions with Site 1063 ages in brackets: Laschamp (41 ka), Blake (116 ka), Iceland Basin (190 ka), Pringle Falls (239 ka). These ages are consistent with current age estimates for three of these excursions, but not for "Pringle Falls" which has an apparent age older than a recently published estimate by ˜28 kyr. For each of these excursions (termed Category 1 excursions), virtual geomagnetic poles (VGPs) reach high southerly latitudes implying paired polarity reversals of the Earth's main dipole field, that apparently occurred in a brief time span (<2 kyr in each case), several times shorter than the apparent duration of regular polarity transitions. In addition, several intervals of low paleomagnetic inclination (low and negative in one case) are observed both in u-channel and discrete samples at ˜318 ka (MIS 9), ˜412 ka (MIS 11) and in the 500-600 ka interval (MIS 14-15). These "Category 2" excursions may constitute inadequately recorded (Category 1) excursions, or high amplitude secular variation.

The Role of CREB, SRF, and MEF2 in Activity-Dependent Neuronal Plasticity in the Visual Cortex.

PubMed

Pulimood, Nisha S; Rodrigues, Wandilson Dos Santos; Atkinson, Devon A; Mooney, Sandra M; Medina, Alexandre E

2017-07-12

The transcription factors CREB (cAMP response element binding factor), SRF (serum response factor), and MEF2 (myocyte enhancer factor 2) play critical roles in the mechanisms underlying neuronal plasticity. However, the role of the activation of these transcription factors in the different components of plasticity in vivo is not well known. In this study, we tested the role of CREB, SRF, and MEF2 in ocular dominance plasticity (ODP), a paradigm of activity-dependent neuronal plasticity in the visual cortex. These three proteins bind to the synaptic activity response element (SARE), an enhancer sequence found upstream of many plasticity-related genes (Kawashima et al., 2009; Rodríguez-Tornos et al., 2013), and can act cooperatively to express Arc , a gene required for ODP (McCurry et al., 2010). We used viral-mediated gene transfer to block the transcription function of CREB, SRF, and MEF2 in the visual cortex, and measured visually evoked potentials in awake male and female mice before and after a 7 d monocular deprivation, which allowed us to examine both the depression component (Dc-ODP) and potentiation component (Pc-ODP) of plasticity independently. We found that CREB, SRF, and MEF2 are all required for ODP, but have differential effects on Dc-ODP and Pc-ODP. CREB is necessary for both Dc-ODP and Pc-ODP, whereas SRF and MEF2 are only needed for Dc-ODP. This finding supports previous reports implicating SRF and MEF2 in long-term depression (required for Dc-ODP), and CREB in long-term potentiation (required for Pc-ODP). SIGNIFICANCE STATEMENT Activity-dependent neuronal plasticity is the cellular basis for learning and memory, and it is crucial for the refinement of neuronal circuits during development. Identifying the mechanisms of activity-dependent neuronal plasticity is crucial to finding therapeutic interventions in the myriad of disorders where it is disrupted, such as Fragile X syndrome, Rett syndrome, epilepsy, major depressive disorder, and autism spectrum disorder. Transcription factors are essential nuclear proteins that trigger the expression of gene programs required for long-term functional and structural plasticity changes. Our results elucidate the specific role of the transcription factors CREB, SRF, and MEF2 in the depression and potentiation components of ODP in vivo , therefore better informing future attempts to find therapeutic targets for diseases where activity-dependent plasticity is disrupted. Copyright © 2017 the authors 0270-6474/17/376628-10$15.00/0.

The Role of CREB, SRF, and MEF2 in Activity-Dependent Neuronal Plasticity in the Visual Cortex

PubMed Central

Rodrigues, Wandilson dos Santos; Mooney, Sandra M.

2017-01-01

The transcription factors CREB (cAMP response element binding factor), SRF (serum response factor), and MEF2 (myocyte enhancer factor 2) play critical roles in the mechanisms underlying neuronal plasticity. However, the role of the activation of these transcription factors in the different components of plasticity in vivo is not well known. In this study, we tested the role of CREB, SRF, and MEF2 in ocular dominance plasticity (ODP), a paradigm of activity-dependent neuronal plasticity in the visual cortex. These three proteins bind to the synaptic activity response element (SARE), an enhancer sequence found upstream of many plasticity-related genes (Kawashima et al., 2009; Rodríguez-Tornos et al., 2013), and can act cooperatively to express Arc, a gene required for ODP (McCurry et al., 2010). We used viral-mediated gene transfer to block the transcription function of CREB, SRF, and MEF2 in the visual cortex, and measured visually evoked potentials in awake male and female mice before and after a 7 d monocular deprivation, which allowed us to examine both the depression component (Dc-ODP) and potentiation component (Pc-ODP) of plasticity independently. We found that CREB, SRF, and MEF2 are all required for ODP, but have differential effects on Dc-ODP and Pc-ODP. CREB is necessary for both Dc-ODP and Pc-ODP, whereas SRF and MEF2 are only needed for Dc-ODP. This finding supports previous reports implicating SRF and MEF2 in long-term depression (required for Dc-ODP), and CREB in long-term potentiation (required for Pc-ODP). SIGNIFICANCE STATEMENT Activity-dependent neuronal plasticity is the cellular basis for learning and memory, and it is crucial for the refinement of neuronal circuits during development. Identifying the mechanisms of activity-dependent neuronal plasticity is crucial to finding therapeutic interventions in the myriad of disorders where it is disrupted, such as Fragile X syndrome, Rett syndrome, epilepsy, major depressive disorder, and autism spectrum disorder. Transcription factors are essential nuclear proteins that trigger the expression of gene programs required for long-term functional and structural plasticity changes. Our results elucidate the specific role of the transcription factors CREB, SRF, and MEF2 in the depression and potentiation components of ODP in vivo, therefore better informing future attempts to find therapeutic targets for diseases where activity-dependent plasticity is disrupted. PMID:28607167

IODP Expedition 335: Deep Sampling in ODP Hole 1256D

NASA Astrophysics Data System (ADS)

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

2012-04-01

Observations of the gabbroic layers of untectonized ocean crust are essential to test theoretical models of the accretion of new crust at mid-ocean ridges. Integrated Ocean Drilling Program (IODP) Expedition 335 ("Superfast Spreading Rate Crust 4") returned to Ocean Drilling Program (ODP) Hole 1256D with the intention of deepening this reference penetration of intact ocean crust a significant distance (~350 m) into cumulate gabbros. Three earlier cruises to Hole 1256D (ODP 206, IODP 309/312) have drilled through the sediments, lavas, and dikes and 100 m into a complex dike-gabbro transition zone. Operations on IODP Expedition 335 proved challenging throughout, with almost three weeks spent re-opening and securing unstable sections of the hole. When coring commenced, the comprehensive destruction of the coring bit required further remedial operations to remove junk and huge volumes of accumulated drill cuttings. Hole-cleaning operations using junk baskets were successful, and they recovered large irregular samples that document a hitherto unseen sequence of evolving geological conditions and the intimate coupling between temporally and spatially intercalated intrusive, hydrothermal, contact-metamorphic, partial melting, and retrogressive processes. Hole 1256D is now clean of junk, and it has been thoroughly cleared of the drill cuttings that hampered operations during this and previous expeditions. At the end of Expedition 335, we briefly resumed coring before undertaking cementing operations to secure problematic intervals. To ensure the greatest scientific return from the huge efforts to stabilize this primary ocean lithosphere reference site, it would be prudent to resume the deepening of Hole 1256D in the nearest possible future while it is open to full depth. doi:10.2204/iodp.sd.13.04.2011

Going Online With Ocean Drilling Publications

NASA Astrophysics Data System (ADS)

Klaus, A. D.; Petronotis, K. E.

2003-12-01

In 1999, the Ocean Drilling Program (ODP) transitioned from a print publication format to a hybrid print/electronic format of its Initial Reports (IR) series. A year later, the Scientific Results (SR) series joined the electronic era. Our mandate was to produce a fully functional electronic publication in HTML and PDF formats that would also function as a professionally typeset printed publication. The IR series disseminates the preliminary scientific knowledge gained during each ODP cruise, whereas the SR series is a venue for publishing independent research conducted after each cruise and often includes extensive data sets and many color images. Although both series are published as a print/CD-ROM hybrid and on the Web, the IR online version follows publication of the CD, whereas the SR online version precedes it. This unique format--neither all print, all electronic, or print with electronic replica of print--led to interesting challenges that few other publishers had to grapple with when going electronic. ODP's formal transition from print to electronic publication was concentrated in a 2-year period, but fortunately, staff members had honed many valuable online editing and production skills prior to that time as a cost-saving means of publishing hardcover books. This made the transition rather seamless for the staff; however, issues pertaining to multiplatform publications still had to be addressed. These included word choices that made sense regardless of whether the material was being viewed on paper, on CD, or on the Web; the creation of alternative citation formats; policies on revising already published electronic material; etc. In our experience, the advantages for publishers and readers have outweighed the growing pains of moving to electronic publishing. For example, SR authors typically see their manuscripts published 4-5 months after acceptance, whereas it used to take 7-9 months. The accessibility of the online publications has significantly widened distribution. And the CD-ROM product allows ODP to enhance the electronic resources available to researchers by including an index of all published IR/SR volume pairs on each CD, detailed site maps, movies, unlimited color images, and other supplementary data sets provided by authors. Our next venture is to digitize the older printed ODP volumes and the Deep Sea Drilling Project (DSDP) series and make these publications available online in HTML and PDF formats as well. This will provide the scientific community with more than 30 years of marine earth science research at the click of a mouse, a legacy that will be built upon by the Integrated Ocean Drilling Program (IODP) in the near future.

Mid-Piacenzian Variability of Nordic Seas Surface Circulation Linked to Terrestrial Climatic Change in Norway

NASA Astrophysics Data System (ADS)

Panitz, Sina; De Schepper, Stijn; Salzmann, Ulrich; Bachem, Paul E.; Risebrobakken, Bjørg; Clotten, Caroline; Hocking, Emma P.

2017-12-01

During the mid-Piacenzian, Nordic Seas sea surface temperatures (SSTs) were higher than today. While SSTs provide crucial climatic information, on their own they do not allow a reconstruction of potential underlying changes in water masses and currents. A new dinoflagellate cyst record for Ocean Drilling Program (ODP) Site 642 is presented to evaluate changes in northward heat transport via the Norwegian Atlantic Current (NwAC) between 3.320 and 3.137 Ma. The record is compared with vegetation and SST reconstructions from Site 642 and SSTs from Iceland Sea ODP Site 907 to identify links between SSTs, ocean currents, and vegetation changes. The dinocyst record shows that strong Atlantic water influence via the NwAC corresponds to higher-than-present SSTs and cool temperate vegetation during Marine Isotope Stage (MIS) transition M2-M1 and KM5. Reduced Atlantic water inflow relative to the warm stages coincides with near-modern SSTs and boreal vegetation during MIS M2, KM6, and KM4-KM2. During most of the studied interval, a strong SST gradient between Sites 642 and 907 indicates the presence of a proto-Arctic Front (AF). An absent gradient during the first half of MIS KM6, due to reduced Atlantic water influence at Site 642 and warm, presumably Atlantic water reaching Site 907, is indicative of a weakened NwAC and East Greenland Current. We conclude that repeated changes in Atlantic water influence directly affect terrestrial climate and that an active NwAC is needed for an AF to develop. Obliquity forcing may have played a role, but the correlation is not consistent.

Deep Ocean Circulation and Nutrient Contents from Atlantic-Pacific Gradients of Neodymium and Carbon Isotopes During the Last 1 Ma

NASA Astrophysics Data System (ADS)

Piotrowski, A. M.; Elderfield, H.; Howe, J. N. W.

2014-12-01

The last few million years saw changing boundary conditions to the Earth system which set the stage for bi-polar glaciation and Milankovich-forced glacial-interglacial cycles which dominate Quaternary climate variability. Recent studies have highlighted the relative importance of temperature, ice volume and ocean circulation changes during the Mid-Pleistocene Transition at ~900 ka (Elderfield et al., 2012, Pena and Goldstein, 2014). Reconstructing the history of global deep water mass propagation and its carbon content is important for fully understanding the ocean's role in amplifying Milankovich changes to cause glacial-interglacial transitions. A new foraminiferal-coating Nd isotope record from ODP Site 1123 on the deep Chatham Rise is interpreted as showing glacial-interglacial changes in the bottom water propagation of Atlantic-sourced waters into the Pacific via the Southern Ocean during the last 1 million years. This is compared to globally-distributed bottom water Nd isotope records; including a new deep western equatorial Atlantic Ocean record from ODP Site 929, as well as published records from ODP 1088 and Site 1090 in the South Atlantic (Pena and Goldstein, 2014), and ODP 758 in the deep Indian Ocean (Gourlan et al., 2010). Atlantic-to-Pacific gradients in deep ocean neodymium isotopes are constructed for key time intervals to elucidate changes in deep water sourcing and circulation pathways through the global ocean. Benthic carbon isotopes are used to estimate deep water nutrient contents of deep water masses and constrain locations and modes of deep water formation. References: Elderfield et al. Science 337, 704 (2012) Pena and Goldstein, Science 345, 318 (2014) Gourlan et al., Quaternary Science Reviews 29, 2484-2498 (2010)

Oceanographic and climatic evolution of the southeastern subtropical Atlantic over the last 3.5 Ma

NASA Astrophysics Data System (ADS)

Petrick, Benjamin; McClymont, Erin L.; Littler, Kate; Rosell-Melé, Antoni; Clarkson, Matthew O.; Maslin, Mark; Röhl, Ursula; Shevenell, Amelia E.; Pancost, Richard D.

2018-06-01

The southeast Atlantic Ocean is dominated by two major oceanic systems: the Benguela Upwelling System, one of the world's most productive coastal upwelling cells and the Agulhas Leakage, which is important for transferring warm salty water from the Indian Ocean to the Atlantic Ocean. Here, we present a multi-proxy record of marine sediments from ODP Site 1087. We reconstruct sea surface temperatures (U37K‧ and TEX86 indices), marine primary productivity (total chlorin and alkenone mass accumulation rates), and terrestrial inputs derived from southern Africa (Ti/Al and Ca/Ti via XRF scanning) to understand the evolution of the Southeast Atlantic Ocean since the late Pliocene. In the late Pliocene and early Pleistocene, ODP Site 1087 was situated within the Benguela Upwelling System, which was displaced southwards relative to present. We recognize a series of events in the proxy records at 3.3, 3.0, 2.2, 1.5, 0.9 and 0.6 Ma, which are interpreted to reflect a combination of changes in the location of major global wind and oceanic systems and local variations in the strength and/or position of the winds, which influence nutrient availability. Although there is a temporary SST cooling observed around the initiation of Northern Hemisphere glaciation (iNHG), proxy records from ODP Site 1087 show no clear climatic transition around 2.7 Ma but instead most of the changes occur before this time. This observation is significant because it has been previously suggested that there should be a change in the location and/or strength of upwelling associated with this climate transition. Rather, the main shifts at ODP Site 1087 occur at ca. 0.9 Ma and 0.6 Ma, associated with the early mid-Pleistocene transition (EMPT), with a clear loss of the previous upwelling-dominated regime. This observation raises the possibility that reorganisation of southeast Atlantic Ocean circulation towards modern conditions was tightly linked to the EMPT, but not to earlier climate transitions.

Reinforcing the North Atlantic backbone: revision and extension of the composite splice at ODP Site 982

NASA Astrophysics Data System (ADS)

Drury, Anna Joy; Westerhold, Thomas; Hodell, David; Röhl, Ursula

2018-03-01

Ocean Drilling Program (ODP) Site 982 represents a key location for understanding the evolution of climate in the North Atlantic over the past 12 Ma. However, concerns exist about the validity and robustness of the underlying stratigraphy and astrochronology, which currently limits the adequacy of this site for high-resolution climate studies. To resolve this uncertainty, we verify and extend the early Pliocene to late Miocene shipboard composite splice at Site 982 using high-resolution XRF core scanning data and establish a robust high-resolution benthic foraminiferal stable isotope stratigraphy and astrochronology between 8.0 and 4.5 Ma. Splice revisions and verifications resulted in ˜ 11 m of gaps in the original Site 982 isotope stratigraphy, which were filled with 263 new isotope analyses. This new stratigraphy reveals previously unseen benthic δ18O excursions, particularly prior to 6.65 Ma. The benthic δ18O record displays distinct, asymmetric cycles between 7.7 and 6.65 Ma, confirming that high-latitude climate is a prevalent forcing during this interval. An intensification of the 41 kyr beat in both the benthic δ13C and δ18O is also observed ˜ 6.4 Ma, marking a strengthening in the cryosphere-carbon cycle coupling. A large ˜ 0.7 ‰ double excursion is revealed ˜ 6.4-6.3 Ma, which also marks the onset of an interval of average higher δ18O and large precession and obliquity-dominated δ18O excursions between 6.4 and 5.4 Ma, coincident with the culmination of the late Miocene cooling. The two largest benthic δ18O excursions ˜ 6.4-6.3 Ma and TG20/22 coincide with the coolest alkenone-derived sea surface temperature (SST) estimates from Site 982, suggesting a strong connection between the late Miocene global cooling, and deep-sea cooling and dynamic ice sheet expansion. The splice revisions and revised astrochronology resolve key stratigraphic issues that have hampered correlation between Site 982, the equatorial Atlantic and the Mediterranean. Comparisons of the revised Site 982 stratigraphy to high-resolution astronomically tuned benthic δ18O stratigraphies from ODP Site 926 (equatorial Atlantic) and Ain el Beida (north-western Morocco) show that prior inconsistencies in short-term excursions are now resolved. The identification of key new cycles at Site 982 further highlights the requirement for the current scheme for late Miocene marine isotope stages to be redefined. Our new integrated deep-sea benthic stable isotope stratigraphy and astrochronology from Site 982 will facilitate future high-resolution late Miocene to early Pliocene climate research.

Geothermal state and fluid flow within ODP Hole 843B: results from wireline logging

NASA Astrophysics Data System (ADS)

Wiggins, Sean M.; Hildebrand, John A.; Gieskes, Joris M.

2002-02-01

Borehole fluid temperatures were measured with a wireline re-entry system in Ocean Drilling Program Hole 843B, the site of the Ocean Seismic Network Pilot Experiment. These temperature data, recorded more than 7 years after drilling, are compared to temperature data logged during Leg 136, approximately 1 day after drilling had ceased. Qualitative interpretations of the temperature data suggest that fluid flowed slowly downward in the borehole immediately following drilling, and flowed slowly upward 7 years after drilling. Quantitative analysis suggests that the upward fluid flow rate in the borehole is approximately 1 m/h. Slow fluid flow interpreted from temperature data only, however, requires estimates of other unmeasured physical properties. If fluid flows upward in Hole 843B, it may have led to undesirable noise for the borehole seismometer emplaced in this hole as part of the Ocean Seismic Network Pilot Experiment. Estimates of conductive heat flow from ODP Hole 843B are 51 mW/m 2 for the sediment and the basalt. These values are lower than the most recent Hawaiian Arch seafloor heat flow studies.

Geochemistry of fluid phases and sediments: Relevance to hydrothermal circulation in Middle Valley, ODP Legs 139 and 169

USGS Publications Warehouse

Gieskes, J.M.; Simoneit, B.R.T.; Shanks, Wayne C.; Goodfellow, W.D.; James, R.H.; Baker, P.A.; Ishibashi, J.-I.

2002-01-01

Geochemical and isotopic studies of pore fluids and solid phases recovered from the Dead Dog and Bent Hill hydrothermal sites in Middle Valley (Ocean Drilling Program Leg 169) have been compared with similar data obtained previously from these sites during Ocean Drilling Program Leg 139. Although generally the hydrothermal systems reflect non-steady state conditions, the data allow an assessment of the history of the hydrothermal processes. Sediment K/A1 ratios as well as the distribution of anhydrite in the sediments suggest that the Dead Dog hydrothermal field has been, and still is, active. In contrast, similar data in the Bent Hill hydrothermal field indicate a waning of hydrothermal activity. Pore fluid and hydrothermal vent data in the Dead Dog hydrothermal field are similar in nature to the data collected during ODP Leg 139. In the area of the Bent Hill sulfide deposit, however, the pore water data indicate that recent wholesale flushing of the sediment column with relatively unaltered seawater has obliterated a previous record of hydrothermal activity in the pore fluids. Data from the deepest part of Hole 1035A in the Bent Hill locality show the presence of hydrothermal fluids at greater depths in this area. This suggests the origin of the hydrothermal fluids found to be emanating from Hole 1035F, which constitutes one of the first man made hydrothermal vents in the Middle Valley hydrothermal system. Similarly, CORKed Hole 858G, because of seal failures, has acted as a hydrothermal vent, with sulfide deposits forming inside the CORK. ?? 2002 Elsevier Science Ltd. All rights reserved.

Ice Sheet History from Antarctic Continental Margin Sediments: The ANTOSTRAT Approach

USGS Publications Warehouse

Barker, P.F.; Barrett, P.J.; Camerlenghi, A.; Cooper, A. K.; Davey, F.J.; Domack, E.W.; Escutia, C.; Kristoffersen, Y.; O'Brien, P.E.

1998-01-01

The Antarctic Ice Sheet is today an important part of the global climate engine, and probably has been so for most of its long existence. However, the details of its history are poorly known, despite the measurement and use, over two decades, of low-latitude proxies of ice sheet volume. An additional way of determining ice sheet history is now available, based on understanding terrigenous sediment transport and deposition under a glacial regime. It requires direct sampling of the prograded wedge of glacial sediments deposited at the Antarctic continental margin (and of derived sediments on the continental rise) at a small number of key sites, and combines the resulting data using numerical models of ice sheet development. The new phase of sampling is embodied mainly in a suite of proposals to the Ocean Drilling Program, generated by separate regional proponent groups co-ordinated through ANTOSTRAT (the Antarctic Offshore Acoustic Stratigraphy initiative). The first set of margin sites has now been drilled as ODP Leg 178 to the Antarctic Peninsula margin, and a first, short season of inshore drilling at Cape Roberts, Ross Sea, has been completed. Leg 178 and Cape Roberts drilling results are described briefly here, together with an outline of key elements of the overall strategy for determining glacial history, and of the potential contributions of drilling other Antarctic margins investigated by ANTOSTRAT. ODP Leg 178 also recovered continuous ultra-high-resolution Holocene biogenic sections at two sites within a protected, glacially-overdeepened basin (Palmer Deep) on the inner continental shelf of the Antarctic Peninsula. These and similar sites from around the Antarctic margin are a valuable resource when linked with ice cores and equivalent sections at lower latitude sites for studies of decadal and millenial-scale climate variation.

Revisiting the Ceara Rise, equatorial Atlantic Ocean: isotope stratigraphy of ODP Leg 154

NASA Astrophysics Data System (ADS)

Wilkens, Roy; Drury, Anna Joy; Westerhold, Thomas; Lyle, Mitchell; Gorgas, Thomas; Tian, Jun

2017-04-01

Isotope stratigraphy has become the method of choice for investigating both past ocean temperatures and global ice volume. Lisiecki and Raymo (2005) published a stacked record of 57 globally distributed benthic δ18O records versus age (LR04 stack). In this study LR04 is compared to high resolution records collected at all of the sites drilled during Ocean Drilling Program (ODP) Leg 154 on the Ceara Rise, in the western equatorial Atlantic Ocean. Newly developed software - the Code for Ocean Drilling Data (CODD) - is used to check data splices of the Ceara sites and better align out-of-splice data with in-splice data. CODD allows to depth and age scaled core images recovered from core table photos enormously facilitating data analysis. The entire splices of ODP Sites 925, 926, 927, 928 and 929 were reviewed. Most changes were minor although several large enough to affect age models based on orbital tuning. We revised the astronomically tuned age model for the Ceara Rise by tuning darker, more clay rich layers to Northern Hemisphere insolation minima. Then we assembled a regional composite benthic stable isotope record from published data. This new Ceara Rise stack provides a new regional reference section for the equatorial Atlantic covering the last 5 million years with an independent age model compared to the non-linear ice volume models of the LR04 stack. Comparison shows that the benthic δ18O composite is consistent with the LR04 stack from 0 - 4 Ma despite a short interval between 1.80 and 1.90 Ma, where LR04 exhibits 2 maxima but where Ceara Rise contains only 1. The interval between 4.0 and 4.5 Ma in the Ceara Rise compilation is decidedly different from LR04, reflecting both the low amplitude of the signal over this interval and the limited amount of data available for the LR04 stack. Our results also point out that precession cycles have been misinterpreted as obliquity in the LR04 stack as suggested by the Ceara Rise composite at 4.2 Ma.

Transient ElectroMagnetic and Electric Self-Potential survey in the TAG hydrothermal field in MAR

NASA Astrophysics Data System (ADS)

Tao, C.; Deng, X.; Wu, G.; Xi, Z.; Zhou, D.; Zuo, L.

2012-12-01

The TAG hydrothermal field is one of the most studied hydrothermal fields. This field covers an area of 5km×5km, which includes low-temperature Mn- and Fe-oxides and nontronites zone, relict massive sulfide mounds as well as active hydrothermal mound(TAG mound) [Thompson, 1985, Rona, 1993]. Drilling program was performed in the ODP (Ocean Drilling Program) Leg 158 in the TAG mound [Humphris, 1996]. In 1996, electrical resistivity survey in the TAG mound was conducted using innovative transient electric dipole-dipole instruments which was carried by DSV 'Alvin' [Cairns et al., 1996, Von Herzen et al., 1996]. In June 2012, the 2nd Leg of the Chinese 26th cruise was carried out in the TAG hydrothermal field at Mid Atlantic Ridge by R/V DAYANGYIHAO. Six TEM (Transient ElectroMagnetic) survey lines were deployed, with four of which across the ODP Leg 158 drilling area. Besides, two SP (Electric Self-Potential) survey lines were across the ODP drilling area. The survey results of TEM preliminary revealed the vertical structure of the TAG hydrothermal field. The survey results of both TEM and SP are consistent with the ODP drilling result, and also agree well with the temperature and water-column anomalies obtained in this leg. Preliminary results show that the TEM and SP methods are capable of revealing the horizontal and vertical distribution of the hydrothermal sulfide fields.

High Sedimentation Rate Paleomagnetic Records for the Last 70 kyrs From the Chilean Margin (ODP Sites 1233, 1234, 1235)

NASA Astrophysics Data System (ADS)

Stoner, J. S.; Lund, S.; Channell, J. E.; Mix, A. C.; Davies, M. H.; Lamy, F.

2008-12-01

Sediments that accumulate at around 1-m/kyr or greater preserve a paleomagnetic record that, under favorable conditions, may record the original geomagnetic input with little smoothing. However, such great rates of accumulation come with a price as features of interest are often deeply buried and may only be adequately recovered using drilling technologies. Here we present a full-vector geomagnetic reconstruction for the last 70,000 yrs from ultrahigh resolution records obtained through ODP drilling (Leg 202) on the Chilean Margin. ODP Site 1233 (41.0 S, 74.26 W, water depth 838 m) provides a 135-mcd u-channel derived directional paleomagnetic secular variation (PSV) and relative paleointensity (RPI) records. The chronology is constrained by AMS radiocarbon dates and tuning of alkenone sea surface temperature to Antarctic ice core temperature records back to 70,000 years BP. To the north, ODP Sites 1234 (36.13 S, 73.40W, water depth 1015 m) and 1235 (36.9 S, 73.33 W, water depth 489 m) provide independently dated shipboard and developing u-channel paleomagnetic records that reproduce many of the geomagnetic features observed at Site 1233 including excursions and high amplitude PSV intervals, while providing additional radiocarbon and isotopic constraints for development of a regional master chronology. All three Sites have exceptionally high glacial sedimentation rates that average 2-m/kyr for 1233, 80-cm/kyr for 1234 and 1-m/kyr for 1235. Fortuitously, the Laschamp magnetic excursion at Site 1233 occurs during an interval where sedimentation rates exceed 3-m/kyr. The Site 1233 chronology indicates that the Laschamp event, centered at 41,000 yrs BP, has a duration in reverse polarity of only 600 yrs, with polarity transitions occurring in less than 200 yrs within a 1500 yr long interval of low RPI. The path of virtual geomagnetic pole (VGP) positions for the Laschamp excursion at Site 1233 is generally consistent with the hypothesis of a simple field geometry because the large clockwise VGP loop mimics the path seen for other sites recording the same excursion. Unlike prior observations, this path begins and ends at approximately the same Alaskan location after making a complete loop through the Pacific to high (> 80 degrees) southerly latitudes. Insights into the dynamics PSV and RPI, the resolution of magnetic stratigraphies, the geomagnetic controls on cosmic ray shielding and whether these might affect climate will also be touched upon.

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.

Paleo-Productivity across the Paleocene-Eocene Thermal Maximum, Walvis Ridge Transect (ODP Sites 1262, 1263, and 1266)

NASA Astrophysics Data System (ADS)

Chun, C. O.; Delaney, M. L.; Zachos, J. C.

2005-12-01

Walvis Ridge transect (Ocean Drilling Program (ODP) Leg 208) provides the first high-resolution depth-transect of deep-sea sediments recovered from the south Atlantic across the P/E boundary. A geographically restricted depth transect (~ 2.2 km, water depths between 2500 and 4770 m) allows us to constrain the surface waters by assuming marine productivity conditions in the overlying water column are similar across all sites. The sediment record will reveal variations for processes that are water-depth dependent. We use the geochemical tracers; biogenic barium, phosphorus, calcium carbonate, and the redox sensitive trace elements manganese and uranium, to reconstruct nutrient burial, paleoproductivity, and bottom water redox chemistry across the Paleocene-Eocene Thermal Maximum (PETM). We calculate our concentrations on a calcium carbonate-free basis to account for dilution by non-carbonate sediments. Trace metal enrichment factors (EFs) are calculated relative to bulk crustal averages. We chose three sites from the depth transect: the shallowest (Site 1263, 2717 m water depth), an intermediate site (Site 1266, 3798 m water depth), and the deepest site (Site 1262, 4755 m water depth). We sampled each site at a sample resolution of ~ 1-2 kyr for 5 m.y. centered at 55 Ma. Uranium EFs at the shallow site exhibits values ~ 5 pre-event and drop to values near crustal averages during and after the carbon isotope excursion (CIE). No dramatic changes in U EFs across the P/E boundary are recorded at the deep and intermediate sites. Mn EFs range between 2.9 -8.6 prior to the event across all three sites, suggesting an oxygenated depositional environment. At the boundary, Mn EFs drop to crustal averages at all sites, then gradually return to pre-event values, indicating more reducing environments during the CIE, a possible explanation for the benthic extinction event (BEE) observed across this transect. Ba excess and reactive phosphorus exhibit decreased concentrations during the CIE with gradual return to pre-event values at the shallowest and deepest sites. We will compare the paleo-productivity and redox chemistry response at the Walvis Ridge sites across the PETM.

K/Ar Dating of Fine Grained Sediments Near Prydz Bay, Antarctica: East Antarctic Ice Sheet Behavior During the Middle-Miocene Climate Transition

NASA Astrophysics Data System (ADS)

Duchesne, A. E.; Pierce, E. L.; Williams, T.; Hemming, S. R.; Johnson, D. L.; May, T.; Gombiner, J.; Torfstein, A.

2012-12-01

¶ The Middle Miocene Climate Transition (MMCT) (~14 Ma) represents a time of major East Antarctic Ice-Sheet (EAIS) expansion, with research suggesting major global sea level fall on the order of ~60 meters (John et al., 2011, EPSL). Ocean Drilling Program (ODP) core data from Site 1165B near Prydz Bay shows an influx of cobbles deposited ~13.8-13.5 Ma, representing a sudden burst of ice-rafted detritus (IRD) during the MMCT. Based on 40Ar/39Ar dating of hornblendes and/or biotite grains, 5 of 6 dated pebbles from a companion study show Wilkes Land origins, indicating transport from over 1500 kilometers away. However, samples throughout this time interval have an anomalously low abundance of sand, thus we seek to understand the sedimentary processes that led to the deposition of these isolated dropstones in a fine matrix through provenance studies of the core's terrigenous fine fraction. Geochemical provenance studies of the terrigenous fraction of marine sediments can aid in identifying past dynamic EAIS behavior; the few outcrops available on the continent provide specific rock characterizations and age constraints from which cored marine sediments can then be matched to using established radiogenic isotope techniques. Here we apply the K/Ar dating method as a provenance tool for identifying the source area(s) of fine-grained terrigenous sediments (<63 μm) deposited during the MMCT. ¶ After source area characterization, we find that the fine-grained sediments from the mid-Miocene show a mixture of both local Prydz Bay sourcing (~400 Ma signature) and Wilkes Land provenance (~900 Ma signature). While locally-derived Prydz Bay sediments are likely to have been delivered via meltwater from ice and deposited as hemipelagic sediments (with some possible bottom current modification, as this is a drift site), sediments sourced from Wilkes Land required transport via large icebergs. Future work will involve further provenance determination on both the fine-grained sediments and the abundant dropstones deposited at ODP Site 1165B during the MMCT. We anticipate that the use of the K/Ar radiometric dating technique as a proxy for the study of glacially transported fine-grained terrigenous materials will enable future Antarctic provenance research and further aid in providing insight into past EAIS behavior.; ODP Core 34X from Site 1165B

ODP Sites 967 and 968 (eastern Mediterranean) revisited and implications for the global oxygen stable isotope chronology of the late Pleistocene

NASA Astrophysics Data System (ADS)

Konijnendijk, Tiuri; Lourens, Lucas; Ziegler, Martin

2013-04-01

ODP Sites 967 and 968 (eastern Mediterranean) revisited and implications for the global oxygen stable isotope chronology of the late Pleistocene ODP Sites 967 and 968, located in the Eastern Mediterranean at the Eratosthenes Seamount, are ideally situated to study both regional and global climate signals. Evidently, changes in the titanium to aluminum ratio of the bulk sediment reflect variations in North African aridity, and hence North African monsoon strength: increased levels of titanium are associated with enhanced windblown dust input from the Sahara and increased levels of aluminum with enhanced runoff from the river Nile. In addition, changes in the benthic foraminiferal stable isotope composition reflect primarily changes in global ice volume and deep sea temperature (Lourens et al., 2010; Ziegler et al., 2010). Here we completed and spliced the Ti/Al and benthic d18O data sets of ODP Site 968 and 967 for the past one million years at approximately 200-400 year resolution. The Ti/Al ratio reflect dominantly precession-controlled African monsoon intensity changes and was used to build an astronomically tuned age model for the composite record. This approach enabled us in first instance to establish an alternative and highly accurate chronology for sapropels in the Eastern Mediterranean, and lead to revisions of existing age models, especially around MIS 11 and 19, when the 405-kyr eccentricity cycle is at a minimum. Color reflectance, typically indicative of sapropels, appears incongruent with insolation forcing during these episodes. Secondly our Ti/Al-based chronology provides an independent age model for the benthic d18O record, which may shed new light upon the relationship between insolation and global climate (e.g. ice volume) changes. Our research indicates negligible differences between our record and the global benthic stack of Lisiecki and Raymo (LR04) between the present and MIS 11. However, there are significant discrepancies in the timing of terminations and onset of glaciation for several isotope stages prior to MIS 11 of up to 10,000 years. The direct comparison of our stable isotope record to insolation appears to suggest a dominant role of obliquity forcing in ice volume behavior for much further into the Pleistocene than generally assumed. References Lourens, L.J., J. Becker, R. Bintanja et al. (2010), Linear and non-linear response of late Neogene glacial cycles to obliquity forcing and implications for the Milankovitch theory. Quaternary Science Reviews 29(1-2), pp.352-365. Ziegler, M., E. Tuenter & L.J. Lourens. (2010), The precession phase of the boreal summer monsoon as viewed from the eastern Mediterranean (ODP Site 968). Quaternary Science Reviews 29(11-12), pp.1481-1490.

Planktic foraminiferal response to early Eocene carbon cycle perturbations in the southeast Atlantic Ocean (ODP Site 1263)

NASA Astrophysics Data System (ADS)

Luciani, Valeria; D'Onofrio, Roberta; Dickens, Gerald R.; Wade, Bridget S.

2017-11-01

At low latitude locations in the northern hemisphere, striking changes in the relative abundances and diversity of the two dominant planktic foraminifera genera, Morozovella and Acarinina, are known to have occurred close to the Early Eocene Climatic Optimum (EECO; 49-53 Ma). Lower Eocene carbonate-rich sediments at Ocean Drilling Program (ODP) Site 1263 were deposited on a bathymetric high (Walvis Ridge) at 40° S, and afford an opportunity to examine such planktic foraminiferal assemblage changes in a temperate southern hemisphere setting. We present here quantified counts of early Eocene planktic foraminiferal assemblages from Hole 1263B, along with bulk sediment stable isotope analyses and proxy measurements for carbonate dissolution. The bulk sediment δ13C record at Site 1263 resembles similar records generated elsewhere, such that known and inferred hyperthermal events can be readily identified. Although some carbonate dissolution has occurred, the well-preserved planktic foraminiferal assemblages mostly represent primary changes in environmental conditions. Our results document the permanent decrease in Morozovella abundance and increase in Acarinina abundance at the beginning of the EECO, although this switch occurred 165 kyr after that at low-latitude northern hemisphere locations. This suggests that unfavourable environmental conditions for morozovellids at the start of the EECO, such as sustained passage of a temperature threshold or other changes in surface waters, occurred at lower latitudes first. The remarkable turnover from Morozovella to Acarinina was widely geographically widespread, although the causal mechanism remains elusive. In addition, at Site 1263, we document the virtual disappearance within the EECO of the biserial chiloguembelinids, commonly considered as inhabiting intermediate water depths, and a reduction in abundance of the thermocline-dwelling subbotinids. We interpret these changes as signals of subsurface water properties, perhaps warming, and the associated contraction of ecological niches.

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.

New Data On The Distribution Of Calcareous Nannofossils During And After The Paleocene/Eocene Transition

NASA Astrophysics Data System (ADS)

Raffi, I.

2004-12-01

Major changes occur among calcareous nannofossil assemblages at the transition from Paleocene to Eocene. In most known P/E boundary sections with complete sediment records, the changes are associated to the brief, intensive interval of global warming, the Paleocene-Eocene Thermal Maximum (PETM), and a concomitant huge perturbation of the global carbon budget, the Carbon Isotope Excursion (CIE). Changes in nannofossil assemblages include: (A) occurrence of Rhomboaster spp. - D. araneus correlative with the CIE; (B) decrease in diversification of Fasciculithus spp. at the CIE onset; (C) occurrence of Zygrhablithus bijugatus and Fasciculithus spp./ Z. bijugatus abundance cross-over within the upper part of the CIE-PETM interval; and (D) extiction of the Paleocene genus Fasciculithus just above the CIE, an event that is closely followed by the further evolution of Rhomboaster - Tribrachiatus plexus. The genus Tribrachiatus subsequently radiates over the next ˜1 million years, a time interval showing further steps in the evolutionary history of calcareous nannofossils (speciations among discoasters and sphenoliths) during the Eocene. Quantitative analyses of selected calcareous nannofossils in deep-sea sections recovered from the Atlantic (DSDP Site 550, ODP Site 929, and ODP Sites 1262 and 1263 of Leg 208) and paleo-equatorial Pacific (ODP Sites 1215, 1220, 1221 of Leg 199) provide new informations about calcareous nannofossils across the Paleocene/Eocene transition interval. The distinctive Rhomboaster spp. - D. araneus association (RD) was previously considered to have a marked provincialism, restricted to the Atlantic Ocean and partially extending to the Tethys seaway and westernmost Indian Ocean. Detailed study of Leg 199 sections (from equatorial Pacific) and preliminary analyses at the P/E boundary of ODP Site 929 (from Ceara Rise in western equatorial Atlantic) and ODP Sites 1262 and 1263 (from Walvis Ridge in southern Atlantic) indicate some difference in the RD distribution. The sudden appearance and short co-existence of R. calcitrapa gr. and D. araneus, and the lowermost occurrence of R. cuspis at the onset of CIE clearly can be extended to the equatorial regions of the Atlantic as well as the Pacific Ocean. The genus Fasciculithus undergoes a substantial decrease in diversification at the onset of CIE, and perish completely shortly afterwards. This significant turnover appears to represent a global event observed in all the known P/E boundary sections from different oceans and paleo-latitudes. The abundance cross-over between Fasciculithus spp. and Z. bijugatus has been observed to occur within the the CIE-PETM interval in several deep-sea sections. In the central paleo-equatorial Pacific Ocean, however, Z. bijugatus specimens were not present at all, whereas a marked increase in abundance of R. cuspis was observed in conjunction with the final decline of Fasciculithus spp. Data from the western paleo-equatorial Atlantic Ocean (Site 929) shows only few Z. bijugatus, implying that this particular early Eocene turnover is absent in these equatorial regions. Thoracosphaera spp. shows a short abundance peak immediately above the carbonate barren interval at the P/E boundary, during the CIE, at paleo-equatorial Pacific Site 1220, which probably reflects a stressed surface water environment.

Magnetic Properties of Submarine and Subaerial Basaltic Glass From the Emperor Seamounts (ODP Leg 197)

NASA Astrophysics Data System (ADS)

Smirnov, A. V.; Tarduno, J. A.

2002-12-01

To evaluate the magnetic properties of submarine and subaerial basaltic glass recovered by drilling during ODP Leg 197 at Detroit Seamount (ODP Site 1203) and Koko Seamount (ODP Site 1206) we have conducted a series of rock magnetic measurements and transmission electron microscopy (TEM) analyses. These glass samples have very low natural remanent magnetizations (NRM < 50 nAm2/g) and their magnetic hysteresis properties are dominated by paramagnetism. After correction for the large paramagnetic signal, samples which show a ferromagnetic component have pseudo-single domain behavior, implying magnetic grain sizes larger than those reported for Holocene glasses. Transmission electron microscopy confirms a very low concentration of crystalline inclusions in the glass. A striking feature often observed during the TEM analyses is the partial (or complete) melting of samples by the electron beam and the apparent formation of new crystalline particles. Thellier experiments on submarine basaltic glass (SBG) show a rapid acquisition of thermoremanent magnetization (TRM) with respect to NRM demagnetization which, taken at face value, implies magnetization in a very weak (<17 μT) ambient field. Yet monitoring of magnetic hysteresis properties during the Thellier experiments (on splits used for paleointensity determinations) indicates a systematic variation in values over the same temperature range where rapid TRM acquisition is observed. We suggest that the experimental data can be explained by the partial melting and neocrystallization of magnetic grains in our SBG samples during the thermal treatments required by the Thellier method, resulting in paleointensity values biased to low values. Magnetic hysteresis monitoring may provide a straight-forward means of detecting partial melting during Thellier experiments.

Organic Matter and δ 13C Throughout a Sub-Basement Red Soil Unit in Hole 1206A Cored During Ocean Drilling Program Leg 197 (Koko Seamount): First Results

NASA Astrophysics Data System (ADS)

Bonaccorsi, R.

2002-12-01

Although the discovery of deep red-brown paleosols during Deep Sea Drilling Project (DSDP) and Ocean Drilling Program (ODP) legs dates back to the 80's [1-3], the potential for preservation of organic matter in these igneous-derived silty-claystone units has been overlooked, and depositional settings have been inferred from only petrologic observations. This work aims to present the first geochemical (TOC, N total) and carbon isotope (δ 13C) data of a metre-thick paleosol Unit (Core 197-1206A-40R-1, 101 cm, to 40R-3, 77 cm; Subunits 18A and 18B, 307.5 to 309.9 mbsf) cored at Site 1206 (Koko Seamount) during ODP Leg 197 (Emperor Seamounts, north Pacific transect)[4-5]. Study of the sources and variation with depth of organic matter in sub-basement Fe-oxide-rich paleosol units from Leg 197 contributes to understanding the palaeoenvironmental history of the Emperor Seamounts prior to, during and after their burial and subsidence (ca. >48 to 56 Ma). Furthermore, preserved organic traces in such an isolated deep Earth system make them a useful test bed for future deep Earth's biosphere-relevant investigations [5-6]. Throughout Core 197-1206A-40R soil unit, Corg (TOC = 0.03-0.07%; 0.049 \\pm 0.011, n=7) and total nitrogen (Ntot = 0.00-0.06 %) are within the range (TOC = 0.05% to 0.12%, n=38) measured for the sub-basement paleosoil/rock units found at Site 1205 [4-5]. The δ 13C (bulk organic matter) values for the paleosol regularly decrease downcore from -25.3 \\permil (Sample 197-1206-40R-1, 103-104, at 307.54 mbsf) to -26.2 \\permil (Sample 197-1206A-40R-2, 130-131; at 308.92 mbsf) in contrast to an exposed Hawaiian oxisol sample (e.g., Ohau-2, 100-105 cm-depth with δ 13C = -23.0 \\permil). Typical uncertainties for these measurements were <\\pm 0.1\\permil to <\\pm 0.3\\permil. It is proposed that δ 13C org values of ca. -25 \\permil to ca. -26 \\permil support a terrestrial, rather than marine source [e.g., 7-8] of organics preserved in the paleosol interbed from Core 197-1206A-40R. Thus, providing additional evidence for red claystone units as soil horizons subaerially formed on the top of Koko and Nintoku Seamounts, and buried by erupted lava flowing in a nearshore environment [1,3-4]. Also, since some bacterial-induced changes in the pristine (?humic) organic compounds may have occurred over time [5], the δ 13C org values could reflect mixing between primary terrestrial/lacustrine and/or primary/secondary (bacterial) organic matter. However, δ 13C alone is inadequate at distinguishing among different carbon sources (i.e., lacustrine algae and C3 land plants, [e.g., 8)]; further use of Isotope Ratio Mass Spectrometry (EA-IRMS) for measuring δ 15N tot in these interesting paleosols is underway. {References: [1] Karpoff, A.M., 1980. Init. Repts. DSDP, 55: Washington, 707-711; [2]Shipboard Scientific Party, 1993a Site 871, Proc. ODP, Init. Repts. 144, 41-103; [3] Holmes, M.A., 1995. Proc. ODP, Scientific Results, v. 144: 381-398; [4] Shipboard Scientific Party, 2002, Proc. ODP, Init. Repts. 197: College Station, TX; [5] Bonaccorsi, R., et al. 2002, Abstract, IAU 2002 Bioastronomy Symposium; [6] Furnes, H., et al., 2001, Abstract, GSA 2001 Annual Meeting; [7] Meyers, P.A., 1994. Chemical Geology, 144, 289-302; [8] Meyers, P.A., 1997. Org. Geochem., 27, 5/6:213-259

Radiometric ages for basement rocks from the Emperor Seamounts, ODP Leg 197

NASA Astrophysics Data System (ADS)

Duncan, Robert A.; Keller, Randall A.

2004-08-01

The Hawaiian-Emperor seamount chain is the "type" example of an age-progressive, hot spot-generated intraplate volcanic lineament. However, our current knowledge of the age distribution within this province is based largely on radiometric ages determined several decades ago. Improvements in instrumentation, sample preparation methods, and new material obtained by recent drilling warrant a reexamination of the age relations among the older Hawaiian volcanoes. We report new age determinations (40Ar-39Ar incremental heating method) on whole rocks and feldspar separates from Detroit (Sites 1203 and 1204), Nintoku (Site 1205), and Koko (Site 1206) Seamounts (Ocean Drilling Program (ODP) Leg 197) and Meiji Seamount (Deep Sea Drilling Project (DSDP) Leg 19, Site 192). Plateaus in incremental heating age spectra for Site 1203 lava flows give a mean age of 75.8 ± 0.6 (2σ) Ma, which is consistent with the normal magnetic polarity directions observed and biostratigraphic age assignments. Site 1204 lavas produced discordant spectra, indicating Ar loss by reheating and K mobilization. Six plateau ages from lava flows at Site 1205 give a mean age of 55.6 ± 0.2 Ma, corresponding to Chron 24r. Drilling at Site 1206 intersected a N-R-N magnetic polarity sequence of lava flows, from which six plateau ages give a mean age of 49.1 ± 0.2 Ma, corresponding to the Chron 21n-22r-22n sequence. Plateau ages from two feldspar separates and one lava from DSDP Site 192 range from 34 to 41 Ma, significantly younger than the Cretaceous age of overlying sediments, which we relate to postcrystallization K mobilization. Combined with new dating results from Suiko Seamount (DSDP Site 433) and volcanoes near the prominent bend in the lineament [, 2002], the overall trend is increasing volcano age from south to north along the Emperor Seamounts, consistent with the hot spot model. However, there appear to be important departures from the earlier modeled simple linear age progression, which we relate to changes in Pacific plate motion and the rate of southward motion of the Hawaiian hot spot.

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)

Rack, Frank; Storms, Michael; Schroeder, Derryl

The primary accomplishments of the JOI Cooperative Agreement with DOE/NETL in this quarter were (1) the preliminary postcruise evaluation of the tools and measurement systems that were used during ODP Leg 204 to study hydrate deposits on Hydrate Ridge, offshore Oregon from July through September 2002; and (2) the preliminary study of the hydrate-bearing core samples preserved in pressure vessels and in liquid nitrogen cryofreezers, which are now stored at the ODP Gulf Coast Repository in College Station, TX. During ODP Leg 204, several newly modified downhole tools were deployed to better characterize the subsurface lithologies and environments hosting microbialmore » populations and gas hydrates. A preliminary review of the use of these tools is provided herein. The DVTP, DVTP-P, APC-methane, and APC-Temperature tools (ODP memory tools) were used extensively and successfully during ODP Leg 204 aboard the D/V JOIDES Resolution. These systems provided a strong operational capability for characterizing the in situ properties of methane hydrates in subsurface environments on Hydrate Ridge during ODP Leg 204. Pressure was also measured during a trial run of the Fugro piezoprobe, which operates on similar principles as the DVTP-P. The final report describing the deployments of the Fugro Piezoprobe is provided in Appendix A of this report. A preliminary analysis and comparison between the piezoprobe and DVTP-P tools is provided in Appendix B of this report. Finally, a series of additional holes were cored at the crest of Hydrate Ridge (Site 1249) specifically geared toward the rapid recovery and preservation of hydrate samples as part of a hydrate geriatric study partially funded by the Department of Energy (DOE). In addition, the preliminary results from gamma density non-invasive imaging of the cores preserved in pressure vessels are provided in Appendix C of this report. An initial visual inspection of the samples stored in liquid nitrogen is provided in Appendix D of this report.« less

Insights into magmatic processes and hydrothermal alteration of in situ superfast spreading ocean crust at ODP/IODP site 1256 from a cluster analysis of rock magnetic properties

NASA Astrophysics Data System (ADS)

Dekkers, Mark J.; Heslop, David; Herrero-Bervera, Emilio; Acton, Gary; Krasa, David

2014-08-01

We analyze magnetic properties from Ocean Drilling Program (ODP)/Integrated ODP (IODP) Hole 1256D (6°44.1' N, 91°56.1' W) on the Cocos Plate in ˜15.2 Ma oceanic crust generated by superfast seafloor spreading, the only drill hole that has sampled all three oceanic crust layers in a tectonically undisturbed setting. Fuzzy c-means cluster analysis and nonlinear mapping are utilized to study down-hole trends in the ratio of the saturation remanent magnetization and the saturation magnetization, the coercive force, the ratio of the remanent coercive force and coercive force, the low-field magnetic susceptibility, and the Curie temperature, to evaluate the effects of magmatic and hydrothermal processes on magnetic properties. A statistically robust five cluster solution separates the data predominantly into three clusters that express increasing hydrothermal alteration of the lavas, which differ from two distinct clusters mainly representing the dikes and gabbros. Extensive alteration can obliterate magnetic property differences between lavas, dikes, and gabbros. The imprint of thermochemical alteration on the iron-titanium oxides is only partially related to the porosity of the rocks. Thus, the analysis complements interpretation based on electrofacies analysis. All clusters display rock magnetic characteristics compatible with an ability to retain a stable natural remanent magnetization suggesting that the entire sampled sequence of ocean crust can contribute to marine magnetic anomalies. Paleointensity determination is difficult because of the propensity of oxyexsolution during laboratory heating and/or the presence of intergrowths. The upper part of the extrusive sequence, the granoblastic dikes, and moderately altered gabbros may contain a comparatively uncontaminated thermoremanent magnetization.

The Pleistocene evolution of the East Antarctic Ice Sheet in the Prydz bay region: Stable isotopic evidence from ODP Site 1167

USGS Publications Warehouse

Theissen, K.M.; Dunbar, R.B.; Cooper, A. K.; Mucciarone, D.A.; Hoffmann, D.

2003-01-01

Ocean Drilling Program Leg 188, Prydz Bay, East Antarctica is part of a larger initiative to explore the Cenozoic history of the Antarctic Ice Sheet through direct drilling and sampling of the continental margins. In this paper, we present stable isotopic results from Ocean Drilling Program (ODP) Site 1167 located on the Prydz Channel Trough Mouth Fan (TMF), the first Antarctic TMF to be drilled. The foraminifer-based ??18O record is interpreted along with sedimentary and downhole logging evidence to reconstruct the Quaternary glacial history of Prydz Bay and the adjacent Lambert Glacier Amery Ice Shelf System (LGAISS). We report an electron spin resonance age date of 36. 9 ?? 3.3 ka at 0.45 m below sea floor and correlate suspected glacial-interglacial cycles with the global isotopic stratigraphy to improve the chronology for Site 1167. The ??18O record based on planktonic (Neogloboquadrina pachyderma (s.)) and limited benthic results (Globocassidulina crassa), indicates a trend of ice sheet expansion that was interrupted by a period of reduced ice volume and possibly warmer conditions during the early-mid-Pleistocene (0.9-1.38 Ma). An increase in ?? 18O values after ??? 900 ka appears to coincide with the mid-Pleistocene climate transition and the expansion of the northern hemisphere ice sheet. The ??18O record in the upper 50 m of the stratigraphic section indicates as few as three glacial-interglacial cycles, tentatively assigned as marine isotopic stages (MIS) 16-21, are preserved since the Brunhes/Matuyama paleomagnetic reversal (780 ka). This suggests that there is a large unconformity near the top of the section and/or that there may have been few extreme advances of the ice sheet since the mid-Pleistocene climate transition resulting in lowered sedimentation rates on the Prydz Channel TMF. The stable isotopic record from Site 1167 is one of the few available from the area south of the Antarctic Polar Front that has been linked with the global isotopic stratigraphy. Our results suggest the potential for the recovery of useful stable isotopic records in other TMFs. ?? 2003 Elsevier B.V. All rights reserved.

Revisiting the Ceara Rise, equatorial Atlantic Ocean: isotope stratigraphy of ODP Leg 154 from 0 to 5 Ma

NASA Astrophysics Data System (ADS)

Wilkens, Roy H.; Westerhold, Thomas; Drury, Anna J.; Lyle, Mitchell; Gorgas, Thomas; Tian, Jun

2017-07-01

Isotope stratigraphy has become the method of choice for investigating both past ocean temperatures and global ice volume. Lisiecki and Raymo (2005) published a stacked record of 57 globally distributed benthic δ18O records versus age (LR04 stack). In this study LR04 is compared to high-resolution records collected at all of the sites drilled during ODP Leg 154 on the Ceara Rise, in the western equatorial Atlantic Ocean. Newly developed software is used to check data splices of the Ceara Rise sites and better align out-of-splice data with in-splice data. Core images recovered from core table photos are depth and age scaled and greatly assist in the data analysis. The entire splices of ODP sites 925, 926, 927, 928 and 929 were reviewed. Most changes were minor although several were large enough to affect age models based on orbital tuning. A Ceara Rise composite record of benthic δ18O is out of sync with LR04 between 1.80 and 1.90 Ma, where LR04 exhibits two maxima but Ceara Rise data contain only one. The interval between 4.0 and 4.5 Ma in the Ceara Rise compilation is decidedly different from LR04, reflecting both the low amplitude of the signal over this interval and the limited amount of data available for the LR04 stack. A regional difference in benthic δ18O of 0.2 ‰ relative to LR04 was found. Independent tuning of Site 926 images and physical property data to the Laskar et al. (2004) orbital solution and integration of available benthic stable isotope data from the Ceara Rise provides a new regional reference section for the equatorial Atlantic covering the last 5 million years.

Coccolithophore export production during the last deglaciation at ODP Site 1089 (Southern Ocean)

NASA Astrophysics Data System (ADS)

Balestrieri, Chiara; Ziveri, Patrizia; Mortyn, Peter Graham; Fornaciari, Eliana; Agnini, Claudia

2017-04-01

In order to assess the Southern Ocean carbonate budget change during the last deglaciation we evaluated the significance of calcification changes observed in calcareous nannofossil assemblages. In particular, we analysed coccolithophore assemblages from TNO57-21, a site survey core drilled as part of ODP Site 1089 (40°57'S; 9°53'E, 4620 m water depth), over the last 25 ky in the Subantarctic South Atlantic. This region is characterized by strong hydrographic gradients and ODP Site 1089 is optimally located in order to monitor the evolution of the Subtropical Front and Subpolar Front and the Agulhas Current (Flores et al., 2003) through time. The mean sedimentation rate is in the range of 15-20 cm/kyr, and the recovery of coccolith-bearing sediments provides a powerful tool to study deep-sea carbonate export production at high-resolution. Much of the CO2 drawdown from the atmosphere has been proposed to be stored into the deep ocean but evidence for increased carbon storage are still elusive (Martínez- Botí et al., 2015). Here, we present data on the Florisphaera profunda index and CaCO3 concentrations per gram of dry sediment, which were used to intepret the productivity trend during the last 25 kyr. These data clearly show a decrease in carbonate production throughout the last deglaciation. Moreover, we have calculated the Calcidiscus leptoporus-Emiliania huxleyi dissolution index (CEX'), which suggests a strong link between increasing coccolith dissolution and the evolution of the bottom water mass dynamics during Termination 1 (TI). Finally, mass estimations of the coccolith carbonate allow us to assess the role of each species as carbonate producers across this time span. These results reveal that during the last 25 ky the productivity was influenced by the mid-latitude westerlies, the study site was bathed by different bottom water masses, and was affected by a shoaling of the lysocline during T1 and the Holocene. References Flores J-A., Marino M., Sierro F.J., Hodell D.A., Charles C.D., 2003. Calcareous plankton dissolution pattern and coccolithophore assemblages during the last 600 kyr at ODP Site 1089 (Cape Basin, South Atlantic): paleoceanographic implications. Palaeogeography Palaeoclimatology Palaeoecology. 196:409-426. Martínez-Botí M.A., Marino G., Foster G.L., Ziveri P., Henehan M.J., Rae J.W., Mortyn P.G., Vance D., 2015. Boron isotope evidence for oceanic carbon dioxide leakage during the last deglaciation. Nature. 518(7538):219-22.

Gas Hydrate Research Site Selection and Operational Research Plans

NASA Astrophysics Data System (ADS)

Collett, T. S.; Boswell, R. M.

2009-12-01

In recent years it has become generally accepted that gas hydrates represent a potential important future energy resource, a significant drilling and production hazard, a potential contributor to global climate change, and a controlling factor in seafloor stability and landslides. Research drilling and coring programs carried out by the Ocean Drilling Program (ODP), the Integrated Ocean Drilling Program (IODP), government agencies, and several consortia have contributed greatly to our understanding of the geologic controls on the occurrence of gas hydrates in marine and permafrost environments. For the most part, each of these field projects were built on the lessons learned from the projects that have gone before them. One of the most important factors contributing to the success of some of the more notable gas hydrate field projects has been the close alignment of project goals with the processes used to select the drill sites and to develop the project’s operational research plans. For example, IODP Expedition 311 used a transect approach to successfully constrain the overall occurrence of gas hydrate within the range of geologic environments within a marine accretionary complex. Earlier gas hydrate research drilling, including IODP Leg 164, were designed primarily to assess the occurrence and nature of marine gas hydrate systems, and relied largely on the presence of anomalous seismic features, including bottom-simulating reflectors and “blanking zones”. While these projects were extremely successful, expeditions today are being increasingly mounted with the primary goal of prospecting for potential gas hydrate production targets, and site selection processes designed to specifically seek out anomalously high-concentrations of gas hydrate are needed. This approach was best demonstrated in a recently completed energy resource focused project, the Gulf of Mexico Gas Hydrate Joint Industry Project Leg II (GOM JIP Leg II), which featured the collection of a comprehensive set of logging-while-drilling (LWD) data through expected gas-hydrate-bearing sand reservoirs in seven wells at three sites in the Gulf of Mexico. The discovery of thick hydrate-bearing sands at two of the sites drilled in the Gulf Mexico validated the integrated geological and geophysical approach used in the pre-drill site selection process to identify gas hydrate reservoirs that may be conducive to energy production. The results of the GOM JIP Leg II LWD expedition are also being used to support the selection of sites for a future drilling, logging, and coring program. Operationally, recent drilling programs, such as ODP Leg 204, IODP Expedition 311, the Japanese Toaki-oki to Kumano-nada drilling leg, the Indian NGHP Expedition 01, and the South Korean Gas Hydrate Research and Development Organization Expedition 01 have demonstrated the great benefit of a multi-leg drilling approach, including the initial acquisition of LWD data that was used to then select sites for the drilling of complex core and wireline logging test holes. It is obvious that a fully integrated site selection approach and a “goal based” operational plan, possibly including numerous drill sites and drilling legs, are required considerations for any future gas hydrate research project.

Declining Atmospheric pCO2 During the Late Miocene and Early Pliocene: New Insights from Paired Alkenone and Coccolith Stable Isotope Barometry

NASA Astrophysics Data System (ADS)

Phelps, S. R.; Polissar, P. J.; deMenocal, P. B.; Swann, J. P.; Guo, M. Y.; Stoll, H. M.

2015-12-01

The relationship between atmospheric CO2 concentrations and climate is broadly understood for the Cenozoic era: warmer periods are associated with higher atmospheric carbon dioxide. This understanding is supported by atmospheric samples of the past 800,000 years from ice cores, which suggest CO2 levels play a key role in regulating global climate on glacial interglacial timescales as well. In this context, the late Miocene poses a challenge: sea-surface temperatures indicate substantial global warmth, though existing data suggest atmospheric CO2 concentrations were lower than pre-industrial values. Recent work using the stable carbon and oxygen isotopic composition of coccolith calcite has demonstrated these organisms began actively diverting inorganic carbon away from calcification and to the site of photosynthesis during the late Miocene. This process occurs in culture experiments in response to low aqueous CO2 concentrations, and suggests decreasing atmospheric pCO2 values during the late Miocene. Here we present new data from ODP Site 806 in the western equatorial Pacific Ocean that supports declining atmospheric CO2 across the late Miocene. Carbon isotope values of coccolith calcite from Site 806 demonstrate carbon limitation and re-allocation of inorganic carbon to photosynthesis starting between ~8 and 6 Ma. The timing of this limitation at Site 806 precedes shifts at other ODP sites, reflecting the higher mixed layer temperature and resultant lower CO2 solubility at Site 806. New measurements of carbon isotope values from alkenones at Site 806 show an increase in photosynthetic carbon fractionation (ɛp) accompanied the carbon limitation evident from coccolith calcite stable isotope data. While higher ɛp is typically interpreted as higher CO2 concentrations, at Site 806, our data suggest it reflects enhancement of chloroplast CO2 from active carbon transport by the coccolithophore algae in response to lower CO2 concentrations. Our new data from ODP Site 806 combined with previous published measurements suggests atmospheric CO2 values declined across the late Miocene and early Pliocene. This decline is coincident with decreasing ocean temperatures suggesting the fundamental relationship between atmospheric CO2 and climate can qualitatively explain late Miocene warmth.

The Impact of One-Dose Package of Medicines on Patient Waiting Time in Dispensing Pharmacy: Application of a Discrete Event Simulation Model.

PubMed

Furushima, Daisuke; Yamada, Hiroshi; Kido, Michiko; Ohno, Yuko

2018-01-01

Improvement in patient waiting time in dispensing pharmacies is an important element for patient and pharmacists. The One-Dose Package (ODP) of medicines was implemented in Japan to support medicine adherence among elderly patients; however, it also contributed to increase in patient waiting times. Given the projected increase in ODP patients in the near future owing to rapid population aging, development of improved strategies is a key imperative. We conducted a cross-sectional survey at a single dispensing pharmacy to clarify the impact of ODP on patient waiting time. Further, we propose an improvement strategy developed with use of a discrete event simulation (DES) model. A total of 673 patients received pharmacy services during the study period. A two-fold difference in mean waiting time was observed between ODP and non-ODP patients (22.6 and 11.2 min, respectively). The DES model was constructed with input parameters estimated from observed data. Introduction of fully automated ODP (A-ODP) system was projected to reduce the waiting time for ODP patient by 0.5 times (from 23.1 to 11.5 min). Furthermore, assuming that 40% of non-ODP patients would transfer to ODP, the waiting time was predicted to increase to 56.8 min; however, introduction of the A-ODP system decreased the waiting time to 20.4 min. Our findings indicate that ODP is one of the elements that increases the waiting time and that it might become longer in the future. Introduction of the A-ODP system may be an effective strategy to improve waiting time.

Sea Surface Temperatures in the Indo-Pacific Warm Pool During the Early Pliocene Warm Period

NASA Astrophysics Data System (ADS)

Dekens, P. S.; Ravelo, A. C.; Griffith, E. M.

2010-12-01

The Indo-Pacific warm pool (IPWP) plays an important role in both regional and global climate, but the response of this region to anthropogenic climate change is not well understood. While the early Pliocene is not a perfect analogue for anthropogenic climate change, it is the most recent time in Earth history when global temperatures were warmer than they are today for a sustained period of time. SST in the eastern equatorial Pacific was 2-4○C warmer in the early Pliocene compared to today. A Mg/Ca SST at ODP site 806 in the western equatorial Pacific indicates that SST were stable through the last 5Ma (Wara et al., 2005). We generated a G. sacculifer Mg/Ca record in the Indian Ocean (ODP sit 758) for the last 5 Ma, which also shows that IPWP SST has remained relatively stable through the last 5 Ma and was not warmer in the early Pliocene compared today. A recent paper suggests that the Mg/Ca of seawater may have varied through the last 5 Ma and significantly affected Mg/Ca SST estimates (Medina-Elizalde et al., 2008). However, there is considerable uncertainty in the estimates of seawater Mg/Ca variations through time. We will present a detailed examination of these uncertainties to examine the possible range of seawater Mg/Ca through the last 5 Ma. Due to the lack of culturing work of foraminifera at different Mg/Ca ratios in the growth water there is also uncertainty in how changes in seawater Mg/Ca will affect the temperatures signal in the proxy. We will explore how uncertainties in the record of seawater Mg/Ca variations through time and its effect on the Mg/Ca SST proxy potentially influence the interpretation of the Mg/Ca SST records at ODP sites 806 and 758 in the IPWP, and ODP site 847 in the eastern equatorial Pacific. We will also explore how adjustment of the Mg/Ca SST estimates (due to reconstructed Mg/Ca seawater variations) affects the δ18O of water when adjusted Mg/Ca SST estimates are paired with δ18O measurements of the same samples.

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

Iron and Sulfur Species and Sulfur Isotopic Compositions of Authigenic Pyrite in Gas Hydrate-Bearing Sediments from Hydrate Ridge, Cascadia Margin (ODP Leg 204): A Proposal of Conceptual Models to Indicate the Non-Steady State Depositional and Diagenetic Processes

NASA Astrophysics Data System (ADS)

Liu, C.; Jiang, S. Y.; Su, X.

2017-12-01

Two accretionary sediment sequences from Sites 1245 and 1252 recovered during Ocean Drilling Program (ODP) Leg 204 at Hydrate Ridge, Cascadia Margin were investigated to explore the non-steady state depositional and diagenetic history. Five iron species and three sulfur species were chemically extracted, and their concentrations and the sulfur isotopic compositions of pyrite were determined. After the mineral recognitions of these species and detailed comparative analyses, the aerobic history of bottom seawater has been determined. The formation of pyrite is thought to be controlled by the limited production of hydrogen sulfide relative to the supply of reactive iron. Also, the intrusion of oxygen by bioturbation would oxidize the reduced sulfur species and further suppress pyritization. To explain the geochemical relationship between pyrite and siderite and the sulfur isotope characteristics of pyrite, we propose seven conceptual models based on the variations in depositional rate and methane flux, and the models succeed in explaining the geochemical results and are validated by the observed non-steady state events. These models may contribute to the reconstruction of the non-steady state processes in other research areas in the future.

Glacial Erosion of Antarctica Evidenced by a Rapid Nd Isotope Excursion Associated with the Eocene-Oligocene Transition

NASA Astrophysics Data System (ADS)

Pusz, A. E.; Scher, H. D.; Thunell, R.

2010-12-01

The Eocene-Oligocene transition (EOT) marks the largest change in global climate over the past 50 million years. The EOT is characterized by a two step increase in benthic foraminiferal δ18O that culminated at the Eocene-Oligocene Glacial Maximum. The δ18O increase reflects a combination of deep-water temperature change and the first development of continental-scale ice sheets on Antarctica during the Cenozoic. We present two new high-resolution coupled benthic foraminiferal δ18O and fossil fish tooth neodymium (Nd) isotope records across the EOT from South Atlantic Ocean Drilling Program (ODP) Sites 1090 (Agulhas Ridge, 42°54’S, 8°54’E, 3200 m paleo-depth) and 1265 (Walvis Ridge, 28°50’S, 2°38’E, 2400 m paleo-depth). The least radiogenic Nd values of -7.5 at Site 1090 and -8.1 at Site 1265 occur in step with the benthic δ18O shifts at these two sites. Data from Sites 1090 and 1265 are in agreement with coupled benthic δ18O and ɛNd records from ODP Site 738 on the Kerguelen Plateau. The magnitude of the ɛNd excursion is 1.0 at Site 1265, 1.5 at Site 1090, and 3.0 at Site 738. The origin of nonradiogenic Nd associated with the excursions at Sites 1265, 1090, and 738 is likely glacial erosion of old, Precambrian and Proterozoic bedrock from the Antarctic continent during ice sheet formation. This explanation is preferred over a pulse of Northern Component Water because the abrupt ɛNd decrease at the Agulhas and Walvis ridges is half the magnitude of that at Site 738, which is farthest from the influence of a North Atlantic derived deep-water mass source. We interpret the Nd isotope records to reflect the input of a large amount of glacially transported detrital material from the east Antarctic continent that was funneled through the Lambert Graben towards Prydz Bay. The abrupt and coincident character of the ɛNd shift indicates the eroded material was quickly spread through the Southern Ocean and diluted by mixing with other water masses.

High resolution stable isotope and carbonate variability during the early Oligocene climate transition: Walvis Ridge (ODP Site 1263)

USGS Publications Warehouse

2007-01-01

resolution reconstruction of the Eocene/Oligocene from the Atlantic basin to date, and provide us with a unique opportunity to investigate the fine-scale interplay of glaciation and the global carbon cycle.

Climatic and Oceanographic Changes Across the Eocene-Oligocene Boundary: Results From South Atlantic ODP Site 1090

NASA Astrophysics Data System (ADS)

Pusz, A. E.; Thunell, R. C.; Scher, H. D.; Barbeau, D. L.; Miller, K. G.; Wright, J. D.

2008-12-01

The Eocene-Oligocene (E-O) boundary is marked by one of the largest climate transitions of the past 50 Ma. The Oi-1 event is characterized by a 1.0‰ increase in benthic foraminiferal δ 18O that occurred at ca. 33.5 Ma. This δ 18O shift has mainly been attributed to large-scale Antarctic ice- sheet growth, whereas deep-water temperature change during Oi-1 remains unresolved. However, recent studies have suggested that this event and its precursor (EOT-1) require the presence of significant ice sheets in Antarctica and the Northern Hemisphere, a eustatic lowering of ~150 meters, and ice-volume storage that is ~2.0 to 2.5 times that of modern ice sheets. We examined the δ 18O and δ 13C of the benthic foraminifera Cibicidoides from South Atlantic ODP site 1090 during Oi-1 at a 10 ka resolution. The benthic δ 18O record from site 1090 shows an overall ~1.5‰ step-wise increase composed primarily of a 0.5‰ shift at ca. 33.8 Ma followed by an even larger 1.0‰ shift at ca. 33.5 Ma, similar to the punctuated shift across the E-O transition documented at sites 1218, 522, and St. Stephens Quarry. Our benthic foraminiferal δ 13C record for site 1090 displays a 1.0‰ increase associated with Oi-1 that is coeval with the δ 18O change. In addition, we analyzed planktonic foraminiferal δ 18O and δ 13C (Subbotina) across this interval. Our planktonic δ 18O data show a transient (<200 kyr) increase of 1.5‰ at 34.0 Ma that we attribute to a change in the structure of the thermocline. A planktonic foraminiferal δ 13C decrease at ca. 34.1 Ma supports the interpretation of a stronger thermocline with a coeval drop in the vertical carbon isotope gradient between the thermocline-dwelling planktonic and deep-dwelling benthic foraminifera. Additional planktonic and benthic foraminiferal stable isotope data from South Atlantic ODP site 1265 across the E-O interval should help determine the cause of the planktonic foraminiferal δ 18O and δ 13C changes. We also investigated changes in deep water circulation patterns during Oi-1 at site 1090 using Nd isotope ratios from fossil fish teeth, which display a trend towards less radiogenic values during the E-O transition, culminating at Oi-1 (~33.5 Ma). Lower 143Nd/144Nd isotopic ratios in seawater are consistent with Nd from an ancient continental source. Thus, these results may reflect a change in the Southern Ocean endmember 143Nd/144Nd value in response to the exhumation and erosion of ancient east Antarctic craton(s) during ice sheet growth. The Nd isotope results from ODP Site 1090 corroborate findings from Kerguelan Plateau and Maud Rise sediment cores.

Education and Outreach Plans for the U.S. Drillship in IODP

NASA Astrophysics Data System (ADS)

White, K. S.; Reagan, M.; Klaus, A. D.

2003-12-01

The Integrated Ocean Drilling Program (IODP) began on October 1, 2003, following the end of operations of the 20-year Ocean Drilling Program (ODP). Education and outreach is a key component of IODP both nationally and internationally. The JOI Alliance (Joint Oceanographic Institutions, Inc., Texas A&M University, and Lamont Doherty Earth Observatory of Columbia University) will lead activities related to the U.S. drillship, coordinating these education and outreach efforts with those undertaken by the Central Management Organization, other IODP platform operators, and a U.S. Science Support Program successor. The Alliance will serve the national and assist the international scientific drilling communities by providing the results from the U.S. vessel to the public, government representatives, and scientists. The Alliance will expand upon media outreach strategies that were successful in ODP, such as issuing press releases at the conclusion of each leg and for major scientific breakthroughs; conducting tours, press conferences, and events during port calls; working with the press at major scientific meetings, and encouraging journalists to sail on expeditions. The Alliance will increase its education role by developing, coordinating, and disseminating educational materials and programs for teachers and students on the scientific themes and discoveries of IODP science. An important component of the outreach plan is using the vessel and associated laboratories and repositories as classrooms. IODP plans include multiple ship berths each year for teachers, based on the success of a pilot program conducted by ODP in 2001. This program, featuring a teacher onboard for a cruise, was accompanied by a distance-learning program and on-line curriculum models. Teachers can tour, both virtually and directly, laboratories and core repositories and participate in scheduled activities and courses. Using science conducted onboard the ship, the Alliance will develop online curriculum materials, as well as publications and fact sheets geared toward nonscientists. The Alliance will partner with existing scientific and education organizations, including programs at their universities, to widely disseminate IODP results and materials.

Preoperative Anemia Is Associated With Failure of Open Debridement Polyethylene Exchange in Acute and Acute Hematogenous Prosthetic Joint Infection.

PubMed

Swenson, Richard D; Butterfield, James A; Irwin, Timothy J; Zurlo, John J; Davis, Charles M

2018-06-01

Acute and acute hematogenous prosthetic joint infections (PJIs) are often treated with open debridement and polyethylene exchange (ODPE) in an effort to save the prosthesis, decrease morbidity, and reduce costs. However, failure of ODPE may compromise a subsequent 2-stage treatment. The purpose of this study is to identify patient factors that impact the success of ODPE for acute and acute hematogenous PJIs. A retrospective review examined comorbidities, preoperative laboratory values, and patient history for patients with successful and failed ODPE treatment for acute perioperative or acute hematogenous periprosthetic hip or knee joint infections. Successful treatment was defined as retaining a well-fixed implant without the need for additional surgery for a minimum of 6-month follow-up with or without lifelong oral maintenance antibiotics. Fifty-three of 72 patients (73.6%) underwent successful ODPE. Of the 19 failures, 14 completed 2-stage revision with one subsequent known failure for recurrent infection. Patients with a Staphylococcus aureus infection were more likely to fail ODPE (48.3% vs 11.6%, P = .0012, odds ratio 7.1, 95% confidence interval 2.3-25.3). Patients with a preoperative hematocrit ≤32.1 were also more likely to fail ODPE (55% vs 16%, P = .0013, odds ratio 6.7, 95% confidence interval 2.2-22.4). When neither risk factor was present, 97.1% of PJIs were successfully treated with ODPE. S aureus infection and preoperative hematocrit ≤32.1 are independent risk factors for ODPE failure. ODPE is a safe alternative to 2-stage revision in patients without preoperative anemia and without S aureus infection. Two-thirds of patients with a failed ODPE were successfully treated with a 2-stage reimplantation. Copyright © 2018 Elsevier Inc. All rights reserved.

High-Resolution Paleomagnetic Observations from Ocean Drilling: Insights from Coring Thick Sediment Drift Deposits

NASA Astrophysics Data System (ADS)

Acton, G. D.; Clement, B. M.; Lund, S. P.; Okada, M.; Williams, T.

2003-04-01

With the advent of the Hydraulic Piston Corer at the end of the Deep Sea Drilling Program and its enhanced successor, the Advanced Piston Corer (APC), developed by the Ocean Drilling Program (ODP), coring through thick (>100 m), rapidly deposited sequences of unconsolidated to partially consolidated sediments with near 100% recovery has become common place. Although much of the emphasis for site selection has been based on paleoceanographic objectives, the impact to the field of paleomagnetism has been dramatic, both in the instruments used to analyze the large quantity of core recovered and in the questions that can be answered concerning geomagnetic field behavior and paleoenvironmental conditions. The largest change has come in the construction of relative paleointensity records, which have provided previously unimagined details about how the geomagnetic field varies in strength during stable polarity intervals as well as during reversals and excursions. These records have allowed more realistic models of the geomagnetic field to be developed while also providing a new chronologic tool for high-resolution dating and global correlation of geomagnetic events. Studies of how the paleomagnetic direction varies through time have not advanced as rapidly and have instead mainly been focused on short time intervals across a few geomagnetic reversals. It should, however, be possible to construct and compare secular variation records with millennial or better resolution that span the past one million years from sites around the world as correlation and chronologies between sites improve. We will give an overview that focuses on secular variation records that are being constructed from sediment drifts drilled in the western North Atlantic during ODP Leg 172. Our results will be used to address questions concerning what percent of time the geomagnetic field is in a stable state versus transitional or excursional states, what the relationship is between directional variability and relative paleointensity, which secular variation features are global and which are local, what is the origin of local directional changes, and how climate and rock magnetic changes influence the paleomagnetic signal.

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.

Scatterometry measurement of nested lines, dual space, and rectangular contact CD on phase-shift masks

NASA Astrophysics Data System (ADS)

Lee, Kyung M.; Yedur, Sanjay; Henrichs, Sven; Tavassoli, Malahat; Baik, Kiho

2007-03-01

Evaluation of lithography process or stepper involves very large quantity of CD measurements and measurement time. In this paper, we report on a application of Scatterometry based metrology for evaluation of binary photomask lithography. Measurements were made on mask level with ODP scatterometer then on wafer with CD-SEM. 4 to 1 scaling from mask to wafer means 60nm line on wafer translates to 240nm on mask, easily measurable on ODP. Calculation of scatterometer profile information was performed by a in-situ library-based analysis (5sec/site). We characterized the CD uniformity, linearity, and metal film thickness uniformity. Results show that linearity measured from fixed-pitch, varying line/space ratio targets show good correlation to top-down CD-SEM with R2 of more than 0.99. ODP-SEM correlation results for variable pitch shows that careful examination of scatterometer profile results in order to obtain better correlation to CD SEM, since both tools react differently to the target profile variation. ODP results show that global CD distribution is clearly measurable with less outliers compared to CD SEM data. This is thought to be due to 'averaging' effect of scatterometer. The data show that Scatterometry provides a nondestructive and faster mean of characterizing lithography stepper performanceprofiles. APSM 1st level (before Cr removal) 'dual-space' CDs and EPSM rectangular contacts were also measured with and results demonstrates that Scatterometer is capable of measuring these targets with reasonable correlation to SEM.

Standard biostratigraphic scheme of planktonic foraminifera for the Nankai Trough Seismogenic Zone, northwestern Pacific

NASA Astrophysics Data System (ADS)

Hayashi, H.; Nishi, H.; Ikehara, M.; Tanaka, T.; Matsuzaki, K.

2013-12-01

The Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) was planned for comprehensive understanding of repeated mega-earthquakes along the subduction boundary of the Philippine Sea Plate. One of fundamental purposes of this project is to reconstruct the tectonic history of the seismogenic zone. For this purpose, we need an integrated stratigraphic approach including biostratigraphic method. With respect to previous studies, sediments from the Kumano forarc basin and accretionary complex of the seismogenic zone contain calcareous microfossils such as planktonic foraminifera (Hayashi et al., 2011). In addition, Miocene to Pliocene ocean-floor sediments in the Shikoku basin also contain planktonic foraminifera with several barren interval (Expedition 322 Scientists, 2010). We present a composite planktonic foraminiferal biostratigraphy using five drilling sites of the NanTroSEIZE transect. These sites are placed in the Kumamo forarc basin (Site C0002), upper trench-slope basin (Site C0001), trench slope (Sites C0022), lower trench-slope basin(C0021) and the Shikoku basin (Site C0012). Total 43 biohorizons were recognized from middle Miocene to Pleistocene sequences with three grades of reliability. Among them, 36 biohorizons were reported with astronomically-tuned ages by Wade et al. (2011) and Tian et al. (2008). These astronomical-tuned ages of biohorizons are in good agreement with each other and consistent with magnetostratigraphy. In particular notice to the comparison between the two different timetables, Tian et al.'s (2008) biohorizons are more concordant with calcareous nannofossil data than those of Wade et al. (2011). It can be explained by the difference of biogeographic provinces of planktonic foraminifera: Tian et al. (2008) constructed their astronomically-tuned records by using sediments from ODP Site 1148 in the South China Sea, about 2,300 km southwest of Site C0012, whereas Wade et al. (2011) are mainly based on Atlantic sites (ODP Sites 925 and 926) and eastern equatorial Pacific sites (ODP Legs 111 and 138). We constructed detailed age-depth models by means of oxygen isotope stratigraphy and carbon radioisotope ages for Quaternary sequences of Sites C0002 and C0001. All isotopic mesurements were conducted on monospecific planktonic foraminiferal shells (Globoconella inflata). We determined precise numerical ages of 11 planktonic foraminiferal biohorizons by the age models. The age-depth model of Site C0001 in the trench slope basin clearly indicates stepwise reducing of sedimentation rates at approximately 0.3, 0.8 and 1.3 Ma.

Sea surface temperature estimates for the mid-Piacenzian Indian Ocean—Ocean Drilling Program sites 709, 716, 722, 754, 757, 758, and 763

USGS Publications Warehouse

Robinson, Marci M.; Dowsett, Harry J.; Stoll, Danielle K.

2018-01-30

Despite the wealth of global paleoclimate data available for the warm period in the middle of the Piacenzian Stage of the Pliocene Epoch (about 3.3 to 3.0 million years ago [Ma]; Dowsett and others, 2013, and references therein), the Indian Ocean has remained a region of sparse geographic coverage in terms of microfossil analysis. In an effort to characterize the surface Indian Ocean during this interval, we examined the planktic foraminifera from Ocean Drilling Program (ODP) sites 709, 716, 722, 754, 757, 758, and 763, encompassing a wide range of oceanographic conditions. We quantitatively analyzed the data for sea surface temperature (SST) estimation using both the modern analog technique (MAT) and a factor analytic transfer function. The data will contribute to the U.S. Geological Survey (USGS) Pliocene Research, Interpretation and Synoptic Mapping (PRISM) Project’s global SST reconstruction and climate model SST boundary condition for the mid-Piacenzian and will become part of the PRISM verification dataset designed to ground-truth Pliocene climate model simulations (Dowsett and others, 2013).

Proposed actions are no actions: re-modeling an ontology design pattern with a realist top-level ontology.

PubMed

Seddig-Raufie, Djamila; Jansen, Ludger; Schober, Daniel; Boeker, Martin; Grewe, Niels; Schulz, Stefan

2012-09-21

Ontology Design Patterns (ODPs) are representational artifacts devised to offer solutions for recurring ontology design problems. They promise to enhance the ontology building process in terms of flexibility, re-usability and expansion, and to make the result of ontology engineering more predictable. In this paper, we analyze ODP repositories and investigate their relation with upper-level ontologies. In particular, we compare the BioTop upper ontology to the Action ODP from the NeOn an ODP repository. In view of the differences in the respective approaches, we investigate whether the Action ODP can be embedded into BioTop. We demonstrate that this requires re-interpreting the meaning of classes of the NeOn Action ODP in the light of the precepts of realist ontologies. As a result, the re-design required clarifying the ontological commitment of the ODP classes by assigning them to top-level categories. Thus, ambiguous definitions are avoided. Classes of real entities are clearly distinguished from classes of information artifacts. The proposed approach avoids the commitment to the existence of unclear future entities which underlies the NeOn Action ODP. Our re-design is parsimonious in the sense that existing BioTop content proved to be largely sufficient to define the different types of actions and plans. The proposed model demonstrates that an expressive upper-level ontology provides enough resources and expressivity to represent even complex ODPs, here shown with the different flavors of Action as proposed in the NeOn ODP. The advantage of ODP inclusion into a top-level ontology is the given predetermined dependency of each class, an existing backbone structure and well-defined relations. Our comparison shows that the use of some ODPs is more likely to cause problems for ontology developers, rather than to guide them. Besides the structural properties, the explanation of classification results were particularly hard to grasp for 'self-sufficient' ODPs as compared with implemented and 'embedded' upper-level structures which, for example in the case of BioTop, offer a detailed description of classes and relations in an axiomatic network. This ensures unambiguous interpretation and provides more concise constraints to leverage on in the ontology engineering process.

Trends in Plio-Pleistocene southwest Pacific stable isotope stratigraphy: Implications for orbital forcing of ice sheets and mid-Pliocene sea level estimates

NASA Astrophysics Data System (ADS)

Patterson, M. O.; Mckay, R. M.; Naish, T.; Wilson, G. S.; Ohneiser, C.; Woodard, S. C.; Bostock, H. C.; Caballero-Gill, R. P.

2015-12-01

We present a new high resolution Early to mid-Pliocene (4.3 to 3.0 Ma) benthic stable isotope record (δ18O and δ13C), a revised magnetostratigraphy and an orbitally tuned age model extending the Early Pliocene to Early Pleistocene (4.3 to 1.2 Ma) record for ODP Site 1123. Placing the δ18O and δ13C time series on an orbital-scale age model provides the chronological basis for high-resolution proxy records spanning the Early Pliocene to Early Pleistocene. By comparison with previous published records (DSDP 607, ODP 1090/704, ODP 849, MV0502-AJC), we examine long-term changes in intra and inter-basinal benthic δ13C records in order to trace the ventilation history of deep-water masses. These comparisons highlight that during the warm Early to mid-Pliocene (3.6 to 2.7 Ma) South Atlantic and southwest Pacific gradients where much larger than during the Pleistocene. These findings are not consistent with Late Pleistocene and modern reconstructions in which South Atlantic δ13C values are slightly lower than south Pacific values at depths bathed by LCDW. Thus, indicating that while LCDW bathing the South Atlantic may have had an enhanced NADW signature, such a situation in the southwest Pacific did not exist during the warm mid-Pliocene. Furthermore, while the δ18O record from Site 1123 demonstrates an overall agreement with the global benthic δ18O stack LR04 exhibiting 40-kyr oscillations in ice volume/temperature, the mid to Late Pliocene interval (~3.3 to 2.8 Ma) demonstrates low frequency ice volume/temperature variability consistent with 100-kyr eccentricity. Eustatic sea-level estimates from δ18O values are consistent with all higher-end (22±10 m compared to modern) values for peak interglacial highstands between 2.9-3.2 Ma. Thus, inferring 100-kyr Antarctic ice sheet variability from marine based margins of the East Antarctic Ice Sheet (EAIS) during the mid to Late Pliocene contributed to sea level, whereas after ~2.9 Ma (post interglacial G17) ODP Site δ18O values are inline with eustatic sea-level estimates derived from the benthic δ18O stack, LR04.

Ocean Drilling Program: Janus Web Database

Science.gov Websites

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

Influence of Past Changes in Atmospheric CO2 on Boron/Calcium of Planktic Fossil Foraminifera

NASA Astrophysics Data System (ADS)

Domeyko, R. A.; Allen, K. A.; deMenocal, P. B.

2014-12-01

Culture experiments have revealed that B/Ca of shells grown by the foraminiferal species Globigerinoides ruber increase with increasing seawater pH. Specifically, B/Ca responds to changes in the relative abundance of pH-sensitive dissolved carbon and boron species (Allen et al. 2011, 2012). Here, we present a high-resolution study on fossilized G. ruber from two sites in North Atlantic subtropical gyres (VM25-21 and ODP 1055B) through 20 ka BP to evaluate how B/Ca responds to past changes in atmospheric CO2. Forams were picked and crushed gently, then cleaned and dissolved using a variation of the Boyle and Keigwin (1985) and Barker et al. (2003) cleaning protocols prior to analysis. ODP 1055B (from Carolina Slope, West Atlantic) produced a high-resolution record with lower B/Ca values during the glacial period followed by a rapid shift to higher B/Ca values in the early deglaciation, with values remaining high through the Holocene. These results were not predicted by culture calibrations, but they are consistent with B/Ca records from the Caribbean (ODP 999, Foster et al. 2008), suggesting this pattern is characteristic of surface waters in the greater North Atlantic region.

Mid-Pliocene Planktic Foraminifer Census Data and Alkenone Unsaturation Indices from Ocean Drilling Program Hole 677A

USGS Publications Warehouse

Robinson, Marci; Caballero, Rocio; Pohlman, Emily; Herbert, Timothy; Peck, Victoria; Dowsett, Harry

2008-01-01

The U.S. Geological Survey is conducting a long-term study of mid-Pliocene climatic and oceanographic conditions. One of the key elements of the study involves the use of quantitative composition of planktic foraminifer assemblages in conjunction with other proxies to constrain estimates of sea-surface temperature (SST) and to identify major oceanographic boundaries and water masses. Raw census data are made available as soon as possible after analysis through a series of reports that provide the basic data for future work. In this report we present raw census data (table 1) for planktic foraminifer assemblages in 14 samples from Ocean Drilling Program (ODP) Hole 677A. We also present alkenone unsaturation index (UK'37) analyses for 89 samples from ODP Hole 677A (table 2). ODP Hole 677A is located in the Panama basin, due west of Ecuador at 1?12.138'N., 83?44.220'W., in 3461.2 meters of water (fig. 1). A variety of statistical methods have been developed to transform foraminiferal census data in Pliocene sequences into quantitative estimates of Pliocene SST. Details of statistical techniques, taxonomic groupings, and oceanographic interpretations are presented in more formal publications (Dowsett and Poore, 1990, 1991; Dowsett, 1991, 2007a,b; Dowsett and Robinson, 1998, 2007; Dowsett and others, 1996, 1999).

Constructing Knowledge of Marine Sediments in Introductory Geology and Oceanography Courses Using DSDP, ODP, and IODP Data

NASA Astrophysics Data System (ADS)

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

2008-12-01

Lithologic data from 40 DSDP, ODP, and IODP scientific ocean drilling cores from the Pacific and North Atlantic oceans are the basis for an inquiry-based classroom exercise module for college introductory geology and oceanography courses. Part 1 of this exercise module is designed as an initial inquiry aimed at drawing out student beliefs and prior knowledge. In Parts 2-3 students observe and describe the physical characteristics of sediment cores using digital core photos, and determine the sediment composition using smear slide data and a decision tree. In Part 4 students combine their individual site data to construct a map showing the distribution of the primary marine sediment types of the Pacific and North Atlantic Oceans, and develop hypotheses to explain the distribution of the sediment types shown on their map. The transportable skills of observation, forming questions, plotting data, interpreting data, and scientific synthesis are embedded in this module, benefitting non-majors as well as majors. The exercise module was tested in the 2008 School of Rock program and the 2008 Urbino Summer School for Paleoceanography, and is currently being tested in undergraduate courses at James Madison University, North Hennipen Community College, St. Cloud State University and University of Massachusetts, Amherst in classes that range in size from 16 students to >150 students. The student worksheets, instructor guide, and preliminary evaluation data will be presented.

Paleoclimate of Quaternary Costa Rica: Analysis of Sediment from ODP Site 1242 in the Eastern Tropical Pacific to Explore the Behavior of the Intertropical Convergence Zone (ITCZ) and Oceanic Circulation

NASA Astrophysics Data System (ADS)

Buczek, C. R.; Joseph, L. H.

2017-12-01

Studies of grain size, magnetic fabric, and terrigenous mass accumulation rates (MAR) on oceanic sediment can provide insights into climatic conditions present at or near the time of deposition by helping to delineate changes in rainfall and oceanic circulation intensities. The fairly homogenous hemipelagic nannofossil clays and clayey nannofossil oozes collected in the upper portion of Ocean Drilling Program (ODP) Site 1242 provide a 1.4 million year sediment record from the Cocos Ridge, in relatively shallow waters of the eastern tropical Pacific Ocean, off the coast of present day Central and South America. Information about shifts in rainfall and oceanic circulation provided by this study may be helpful in understanding changes in the location and behavior of the Intertropical Convergence Zone (ITCZ), and/or other climatic factors, in this area during the Pleistocene and Holocene Epochs. Approximately 130 paired side-by-side samples were selected at approximately evenly spaced intervals throughout the uppermost 190 mcd of the core. To obtain terrigenous grain size and MARs, one set of sediment samples was subject to a five-step chemical extraction process to dissolve any oxy-hydroxy coatings, remove the biogenic carbonate and silicate components, and sieve out grains larger than 63 µm. The pre- and post-extraction weights were compared to calculate a terrigenous weight percent (%) from which the terrigenous MAR values were then calculated, with the use of linear sediment rates and dry bulk density measurements determined from shipboard ODP 1242 analyses. Magnetic fabric, or anisotropy of magnetic susceptibility (AMS), was analyzed on a KLY4S-Kappabridge using the second set of samples taken in pmag cubes. Terrigenous MAR values range between 3.1 and 10.9 g/cm2/kyr, while P' (AMS) values range between 1.004 and 1.04 SI. A distinctive trend is noted in both factors, with both exhibiting relatively high initial values that then decrease from the beginning of the record until 1.0-0.8 Ma, and then remain fairly constant (and relatively low) up-core. The initial decline potentially represents a drying of continental climates and a slowing of oceanic currents during the early Pleistocene, possibly due to shifts in the ITCZ or other factors affecting circulation.

Refining the Early and Middle Eocene Geomagnetic Polarity Time Scale: new results from ODP Leg 208 (Walvis Ridge)

NASA Astrophysics Data System (ADS)

Westerhold, T.; Roehl, U.; Frederichs, T.; Bohaty, S. M.; Florindo, F.; Zachos, J. C.; Raffi, I.; Agnini, C.

2015-12-01

Astronomical calibration of the Geomagnetic Polarity Time Scale (GPTS) for the Eocene (34-56 Ma) has advanced tremendously in recent years. Combining a cyclostratigraphic approach based on the recognition of the stable 405-kyr eccentricity cycle of Earth's orbit with high-resolution bio- and magnetostratigraphy from deep-sea sedimentary records (ODP Legs 171B, 189 and 207; IODP Exp. 320/321) resulted in a new calibration of the middle-to-late Eocene GPTS spanning Chrons C12r to C19n (30.9-41.3 Ma). A fully astronomically calibrated GPTS for the Eocene was established recently by integrating cyclo-bio-magnetostratigraphy from ODP Sites 702 and 1263 records spanning the middle Eocene with Site 1258 records covering the early Eocene. Comparison of this deep sea-derived GPTS with GTS2012 and GPTS calibration points from terrestrial successions show overall consistent results, but there are still major offsets for the duration of Chrons C20r, C22r and C23n.2n. Because of the relatively large uncertainty of the calibration point, a radioisotopic dated ash layer in DSDP 516F, at C21n.75 (46.24±0.5 Ma) the duration of C20r in GPTS2012 (2.292 myr) is uncertain. Offsets in durations of C22r and C23n.2n between GPTS2012 and the new astronomical GPTS (~400-kyr longer C22r; ~400-kyr shorter C23n.2n) could be due to uncertainties in the interpretation of Site 1258 magnetostratigraphic data. Here we present new results toward establishing a more accurate and complete bio-, magneto- and chemostratigraphy for South Atlantic Leg 208 sites encompassing magnetochrons C13 to C24 (33 to 56 Ma). Our study aims to integrate paleomagnetic records from multiple drilled sites with physical property data, stable isotope data and XRF core scanning data to construct an astronomically calibrated framework for refining GPTS age estimates. This effort will complete the Early-to-Middle Eocene GPTS and allow evaluation of the relative position of calcareous nannofossil events to magnetostratigraphy.

Capturing the global signature of surface ocean acidification during the PETM

NASA Astrophysics Data System (ADS)

Babila, T. L.; Penman, D. E.; Hoenisch, B.; Kelly, D. C.; Bralower, T. J.; Rosenthal, Y.; Zachos, J. C.

2016-12-01

Anthropogenic greenhouse gas emissions over the last century have elevated atmospheric carbon dioxide concentrations while concomitantly acidifying the oceans. Instrumental records are sparse and limited in duration, making it difficult to separate regional from global trends of ocean acidification. Geologically rapid carbon perturbations such as the Paleocene-Eocene Thermal Maximum (PETM, 56 Ma) are arguably the closest paleo analogue to present climate change. Marine ecosystems experienced dynamic changes during the event, and parallel environmental changes, including acidification and warming. Here we present a synthesis of new and published geochemical reconstructions from various oceanographic settings to determine the magnitude and spatial extent of surface ocean acidification. In the deep ocean, acidification is inferred from widespread dissolution of seafloor carbonates, whereas evidence for surface ocean acidification has emerged from planktonic foraminifera boron proxy records (B/Ca and δ11B) (Penman et al. 2014; Babila et al. 2016). B/Ca and δ11B in surface and thermocline planktonic foraminifera suggest a simultaneous decrease at the PETM onset in all pelagic and shelf sites. Salinity, diagenesis and foraminiferal symbiont loss can complicate the interpretation of boron proxy records. Local salinity changes (based on paired Mg/Ca and δ18O) account for a relatively small component of total B/Ca change. The large range in environmental conditions between sites could explain the subtle differences in absolute values exhibited by the records. Shelf sites (ODP 174AX Bass River and Ancora, NJ) reveal similar absolute values and trends compared to pelagic sites (ODP 1209, N. Pacific), precluding a significant preservation bias on the geochemical records. Southern Ocean sites (ODP 689 and 690) are located in colder surface waters and exhibit a similar decrease in B/Ca, suggesting that temperature and symbiont loss are likely not major factors. We conclude that while the mass of released carbon is comparable to anthropogenic emissions, the rate is much slower, resulting in a less severe degree of undersaturation. Furthermore, the consistent latitudinal pattern of acidification suggests that thermal stress rather than acidification contributed to the observed biotic responses.

High-resolution record of the Laschamp geomagnetic excursion at the Blake-Bahama Outer Ridge

NASA Astrophysics Data System (ADS)

Bourne, Mark D.; Mac Niocaill, Conall; Thomas, Alex L.; Henderson, Gideon M.

2013-12-01

Geomagnetic excursions are brief deviations of the geomagnetic field from behaviour expected during `normal secular' variation. The Laschamp excursion at ˜41 ka was one such deviation. Previously published records suggest rapid changes in field direction and a concurrent substantial decrease in field intensity associated with this excursion. Accurate dating of excursions, and determination of their durations from multiple locations, is vital to our understanding of global field behaviour during these deviations. We present here high-resolution palaeomagnetic records of the Laschamp excursion obtained from two Ocean Drilling Program (ODP) Sites, 1061 and 1062 on the Blake-Bahama Outer Ridge (ODP Leg 172). High sedimentation rates (˜30-40 cm kyr-1) at these locations allow determination of transitional field behaviour during the excursion. Palaeomagnetic measurements of discrete samples from four cores reveal a single excursional feature, across an interval of 30 cm, associated with a broader palaeointensity low. We determine the age and duration of the Laschamp excursion using a stratigraphy linked to the δ18O record from the Greenland ice cores. This chronology dates the Laschamp excursion at the Blake Ridge to 41.3 ka. The excursion is characterized by rapid transitions (less than 200 yr) between stable normal polarity and a partially reversed polarity state. The palaeointensity record is in good agreement between the two sites, revealing two prominent minima. The first minimum is associated with the Laschamp excursion at 41 ka and the second corresponds to the Mono Lake excursion at ˜35.5 ka. We determine that the directional excursion during the Laschamp at this location was no longer than ˜400 yr, occurring within a palaeointensity minimum that lasted 2000 yr. The Laschamp excursion at this location is much shorter in duration than the Blake and Iceland Basin excursions.

Equatorial Kelvin waves generated in the western tropical Pacific Ocean trigger mass and heat transport within the Middle America Trench off Costa Rica

NASA Astrophysics Data System (ADS)

Thomson, Richard E.; Davis, Earl E.

2017-07-01

Sequences of correlated seafloor temperature, current velocity, and acoustic backscatter events recorded at Ocean Drilling Program (ODP) sites at 4300 m depth in the Middle America Trench have been inferred to result from tidally induced turbidity currents generated in the vicinity of the 3300 m deep sill at the southern end of the trench. New data from the borehole observatories extend the temperature records to 11 years (November 2002 to December 2013) and confirm the highly episodic nature of the events. We present satellite altimetry data and ocean circulation model results to show that event timing is correlated with intraseasonal Kelvin wave motions in the equatorial Pacific. The observed temperature events had a mean (±1 standard deviation) occurrence interval of 61 (±24) days, which spans the periods of the first two baroclinic modes. Lag times between peak bottom water temperatures at the ODP sites and the passage of eastward-propagating Kelvin wave crests at locations in the eastern equatorial Pacific are consistent with the time for mode-1 waves to propagate to the southern end of the trench at a mean phase speed of 2.0 m s-1. Findings indicate that Kelvin wave currents augment tidal motions in the vicinity of the sill, triggering turbidity currents that travel northwestward along the trench axis at mean speeds of ˜0.1 m s-1. We conclude that mode-1 (or, possibly, mixed mode-1 and mode-2) baroclinic Kelvin waves generated by large-scale atmospheric processes in the western tropical Pacific lead to heat and mass transport deep within Middle America Trench in the eastern tropical Pacific.

Changing surface water conditions for the last 500 ka in the Southeast Atlantic:Tracking Agulhas leakage using UK37' and δD

NASA Astrophysics Data System (ADS)

Petrick, Benjamin; McClymont, Erin; van der Meer, Marcel; Marret, Fabienne

2015-04-01

The Southeast Atlantic Ocean is an important component of global ocean circulation, as it includes heat and salt transfer into the Atlantic through Agulhas Leakage. Here, we reconstruct sea surface temperatures (SSTs) and sea surface salinity from Ocean Drilling Program (ODP) Site 1087 in the Southeast Atlantic to investigate surface ocean circulation patterns during the late Pleistocene (0-500 ka). The alkenone-derived U37K'index and assemblages of dinoflagellate cysts are used to reconstruct SSTs. The hydrogen isotope composition of the alkenones (δDalkenone) is used to reconstruct changes in sea-surface salinity. The greatest amplitude of SST warming precedes decreases in benthic δ18O and therefore occurs early in the transition from glacials to interglacials. The timing of the early warming is consistent with previously published foraminifera reconstructions from the same site (Caley et al., 2012). However, δDalkenone decreases at the start of interglacials, suggesting that sea surface salinity increased earlier than the deglacial warmings, and indicating that the pattern of Agulhas leakage is more complex than suggested by SST proxies alone. Furthermore, the δDalkenonevalues indicate a strong salinity increases occurred before both MIS 11 and MIS 1, which are both periods where there is evidence of connection between increased Agulhas Leakage and a stronger Atlantic meridional overturning circulation (AMOC). Finally, the ODP site 1087 record shows an overall trend of increasing SSTs and δDalkenone towards the present day, suggesting that Agulhas leakage has strengthened since 500 ka, which may have impacted the intensity of the AMOC. Caley, T., Giraudeau, J., Malaize, B., Rossignol, L., Pierre, C., 2012. Agulhas leakage as a key process in the modes of Quaternary climate changes. Proc. Natl. Acad. Sci. 109, 6835-6839. doi:10.1073/pnas.1115545109

The Initiation of the Southern Central Great Barrier Reef: Multiproxy Study on Periplatform Sediments From ODP Site 1195 on the Marion Plateau (NE Australia)

NASA Astrophysics Data System (ADS)

Dubois, N.; Kindler, P.; Spezzaferri, S.; Coric, S.

2007-12-01

The sediments deposited at ODP Site 1195 (Marion Plateau, NE Australia) record synchronous shifts in their chemistry, mineralogy, grain size and colour at 6 meters below sea floor. These significant changes are interpreted to reflect the onset of the southern province of the Great Barrier Reef (GBR). An increased deposition of carbonate-rich sediments of neritic origin, coincident with a decline in both sedimentation rate and terrigenous input, is attributed to inshore trapping of materials by the reefs. Based on an age model combining magnetostratigraphic and biostratigraphic data, we propose that the southern province of the GBR initiated between 560 and 670 kyr B.P. Our best estimate concurs with previous studies reporting an age between 500 and 930 kyr B.P., albeit constraining more tightly these earlier age estimates. However, it does not support research placing the birth of the GBR in Marine Isotope Stage 11 (about 400 kyr B.P.), nor the recent theory of a worldwide modern reef development at that time.

Early Eocene to Late Miocene Variations in the South Atlantic CCD: Constraints from the Walvis Ridge Depth-Transect (ODP Leg 208)

NASA Astrophysics Data System (ADS)

Lindsey, M. M.; Schellenberg, S. A.

2006-12-01

Carbonate saturation profiles are complex and dynamic products of processes operating on spatiotemporal scales from the "short-term local" (e.g. carbonate export production, carbonate ion concentration) to the "long- term global" (e.g. carbonate-silicate weathering, shelf:basin carbonate partitioning). Thus, a refined history of carbonate saturation may provide insight on global carbon-cycle dynamics. An established, if crude, proxy for reconstructing carbonate saturation is the wt% carbonate content of pelagic sediments, where <20 wt% is ascribed to deposition below the carbonate compensation depth (CCD). A number of now classic works (e.g. Berger and Roth, 1975; van Andel, 1977) established first-order and presumably global Cenozoic CCD fluctuations. The Walvis Ridge depth-transect of ODP Leg 208 represents an excellent opportunity to refine our understanding of the South Atlantic Cenozoic CCD. Wt% carbonate determinations (n = 299) through the Early Eocene to Late Miocene section at Site 1267 are significantly correlated with associated natural gamma ray values (r2 = 0.92). This relationship was used to produce a cm-scale synthetic wt% carbonate record ordinated in the time-domain via the ship-board age-model and in the paleodepth-domain via Sclater and Parsons (1977) crustal age-depth relationship. The Site 1267 record shows good general agreement with previous low-resolution (>10^{5-6} yr) CCD reconstructions and correlates relatively well with estimates of eustatic sea level fluctuations. Ongoing research expands this general approach to shallower and deeper ODP Leg 208 sites to provide greater constraints on the history of the South Atlantic CCD. These data, combined with other proxies (e.g. planktonic foraminifer fragmentation, stable isotopes) and placed within evolving Leg 208 age-models, will provide valuable constraints on cyclic and secular fluctuations in the South Atlantic carbonate saturation profile and their relation to various components of the earth system (e.g. pCO2, sea level, tectonics).

Possible world-wide middle miocene iridium anomaly and its relationship to periodicity of impacts and extinctions

NASA Technical Reports Server (NTRS)

Asaro, F.; Alvarez, W.; Michel, H. V.; Alvarez, L. W.; Anders, Mark H.; Montanari, A.; Kennett, James P.

1988-01-01

In a study of one million years of Middle Miocene sediment deposition in ODP Hole 689B in the Weddell Sea near Antarctica, a single iridium (Ir) anomaly of 44 (+ or - 10) x 10 to the 12th gram Ir per gram rock (ppt) was observed in core 6H, section 3, 50 to 60 cm, after background contributions associated with manganese precipitates and clay are subtracted. The ODP Hole 689B is 10,000 km away from another site, DSDP Hole 588B in the Tasman Sea north of New Zealand, where a single Ir anomaly of 144 + or - 7 ppt over a background of 11 ppt was found in an earlier study of 3 million years of deposition. From chemical measurements the latter deposition was thought to be impact-related. Ir measurements were made, following neutron activation, with the Iridium Coincidence Spectrometer. The age vs depth calibration curves given in the DSDP and ODP preliminary reports indicate the ages of the Iranomalies are identical, 11.7 million years, but the absolute and relative uncertainties in the curves are not known. Based on the newest age data the age estimate is 10 million years. As the Ir was deposited at the two sites at about the same time and they are one quarter of the way around the world from each other it seems likely that the deposition was world-wide. The impact of a large asteroid or comet could produce the wide distribution, and this data is supportive of the impact relationship deduced for Deep Sea Drilling Project (DSDP) 588B from the chemical evidence. If the surface densities of Ir at the two sites are representative of the world-wide average, the diameter of a Cl type asteroid containing the necessary Ir would be 3 + or - 1 km, which is large enough to cause world-wide darkness and hence extinctions although the latter point is disputed.

Methane and other hydrocarbon gases in sediment from the southeastern North American continental margin

USGS Publications Warehouse

Kvenvolden, K.A.; Lorenson, T.D.

2000-01-01

Residual concentrations and distributions of hydrocarbon gases from methane to n-heptane were measured in sediments at seven sites on Ocean Drilling Program (ODP) Leg 164. Three sites were drilled at the Cape Fear Diapir of the Carolina Rise, and one site was drilled on the Blake Ridge Diapir. Methane concentrations at these sites result from microbial generation which is influenced by the amount of pore-water sulfate and possible methane oxidation. Methane hydrate was found at the Blake Ridge Diapir site. The other hydrocarbon gases at these sites are likely the produce of early microbial processes. Three sites were drilled on a transect of holes across the crest of the Blake Ridge. The base of the zone of gas-hydrate occurrence was penetrated at all three sites. Trends in hydrocarbon gas distributions suggest that methane is microbial in origin and that the hydrocarbon gas mixture is affected by diagenesis, outgassing, and, near the surface, by microbial oxidation. Methane hydrate was recovered at two of these three sites, although gas hydrate is likely present at all three sites. The method used here for determining amounts of residual hydrocarbon gases has its limitations and provides poor assessment of gas distributions, particularly in the stratigraphic interval below about ~ 100 mbsf. One advantage of the method, however, is that it yields sufficient quantities of gas for other studies such as isotopic determinations.

Molybdenum mobility and isotopic fractionation during subduction at the Mariana arc

NASA Astrophysics Data System (ADS)

Freymuth, Heye; Vils, Flurin; Willbold, Matthias; Taylor, Rex N.; Elliott, Tim

2015-12-01

The fate of crustal material recycled into the convecting mantle by plate tectonics is important for understanding the chemical and physical evolution of the planet. Marked isotopic variability of Mo at the Earth's surface offers the promise of providing distinctive signatures of such recycled material. However, characterisation of the behaviour of Mo during subduction is needed to assess the potential of Mo isotope ratios as tracers for global geochemical cycles. Here we present Mo isotope data for input and output components of the archetypical Mariana arc: Mariana arc lavas, sediments from ODP Sites 800, 801 and 802 near the Mariana trench and the altered mafic, oceanic crust (AOC), from ODP Site 801, together with samples of the deeper oceanic crust from ODP Site 1256. We also report new high precision Pb isotope data for the Mariana arc lavas and a dataset of Pb isotope ratios from sediments from ODP Sites 800, 801 and 802. The Mariana arc lavas are enriched in Mo compared to elements of similar incompatibility during upper mantle melting, and have distinct, isotopically heavy Mo (high 98Mo/95Mo) relative to the upper mantle, by up to 0.3 parts per thousand. In contrast, the various subducting sediment lithologies dominantly host isotopically light Mo. Coupled Pb and Mo enrichment in the Mariana arc lavas suggests a common source for these elements and we further use Pb isotopes to identify the origin of the isotopically heavy Mo. We infer that an aqueous fluid component with elevated [Mo], [Pb], high 98Mo/95Mo and unradiogenic Pb is derived from the subducting, mafic oceanic crust. Although the top few hundred metres of the subducting, mafic crust have a high 98Mo/95Mo, as a result of seawater alteration, tightly defined Pb isotope arrays of the Mariana arc lavas extrapolate to a fluid component akin to fresh Pacific mid-ocean ridge basalts. This argues against a flux dominantly derived from the highly altered, uppermost mafic crust or indeed from an Indian-like mantle wedge. Thus we infer that the Pb and Mo budgets of the fluid component are dominated by contributions from the deeper, less altered (cooler) portion of the subducting Pacific crust. The high 98Mo/95Mo of this flux is likely caused by isotopic fractionation during dehydration and fluid flow in the slab. As a result, the residual mafic crust becomes isotopically lighter than the upper mantle from which it was derived. Our results suggest that the continental crust produced by arc magmatism should have an isotopically heavy Mo composition compared to the mantle, whilst a contribution of deep recycled oceanic crust to the sources of some ocean island basalts might be evident from an isotopically light Mo signature.

Sediment compaction and pore pressure prediction in deepwater basin of the South China Sea: Estimation from ODP and IODP drilling well data

NASA Astrophysics Data System (ADS)

Xie, Yangbing; Wu, Tuoyu; Sun, Jin; Zhang, Hanyu; Wang, Jiliang; Gao, Jinwei; Chen, Chuanxu

2018-02-01

Overpressure in deepwater basins not only causes serious soft sediment deformation, but also significantly affects the safety of drilling operations. Therefore, prediction of overpressure in sediments has become an important task in deepwater oil exploration and development. In this study, we analyze the drilling data from ODP Leg 184 Sites 1144, 1146, and 1148, and IODP Leg 349 Sites U1431, U1432, U1433, and U1435 to study the sediment compaction and controls in the northern South China Sea. Sedimentation rate, sediment content, distribution area, and buried depth are the factors that influence sediment compaction in the deepwater basin of the South China Sea. Among these factors, the sediment content is the most important. The fitted normal compacted coefficients and mudline porosity for an interval of 50 m shows disciplinary variation versus depth. The pore pressure predicted from different fitted results shows varying overpressure situations. The normal compaction trend from Site 1144 reflects the porosity variation trend in stable deposition basins in the northern South China Sea. The predicted pore pressure shows overpressure at Site 1144, which is attributed to compaction disequilibrium. Nevertheless, the mixed lithology column may influence the predicted over-pressure at Site 1148, which is responsible for the confusing result. Above all, we find that sediment compaction should serve as a proxy for pore pressure in the deepwater basin of the South China Sea.

Milankovitch forcing and role of Indonesian Gateway on middle Miocene climate and carbon cycle: New perspective from the South China Sea, equatorial West Pacific and East Indian Ocean

NASA Astrophysics Data System (ADS)

Holbourn, A.; Kuhnt, W.; Schulz, M.

2003-04-01

The enigmatic long-term positive carbon isotope excursion ("Monterey excursion") in the middle Miocene exhibits an apparent 400 ky cyclicity (long eccentricity cycle of the Milankovitch frequency band). Similar isotope excursion are known from the mid-Cretaceous and may be a characteristic feature of a greenhouse world with extreme warm climate, high sealevel, and a dominantly zonal circulation pattern in the world ocean. This period of extreme warmth (the mid-Miocene climate optimum) ended between 14.2 and 13.8 Ma, when a significant increase in deep-water oxygen isotopic values occurred that was related to the growth of the East Antarctic ice sheet. Plate tectonic movements between Australia and SE Asia, ultimately leading to the closure of the deep water gateway connecting the Indian and Pacific Oceans, started prior to this paleoceanographic change. We used benthic deep water oxygen and carbon isotope curves in combination with new age models at critical locations along the northern margin of the Indonesian Gateway (South China Sea, ODP Site 1146), at the western end of the gateway (NW Australian margin, ODP Site 761) and at the eastern end of the gateway (Ontong Java Plateau, ODP Site 806) to investigate the frequency and amplitude of deep water isotope fluctuations during the middle Miocene. High resolution sediment color reflectance data, benthic carbon isotopes and foraminiferal assemblages are used as proxies of deep-water ventilation and carbon flux. Our results indicate Milankovitch forcing on virtually all proxies and a change from eccentricity to precession driven cyclicity at approximately 15 Ma. Our data reveal increased carbon flux and a restricted deep water exchange between the Pacific Ocean and Indian Ocean through the Indonesian Gateway during the middle Miocene climate optimum. After 13.6 Ma, the decrease in d13C was strongest at Site 806, indicating a marked change in the deep-water circulation of the equatorial West Pacific and a switch to a more distant deep-water source.

Hydraulic Properties of Diatomaceous Structure on Physical Properties and Wire-line Logging - An example of off Sanriku, North Japan -

NASA Astrophysics Data System (ADS)

Ojima, T.; Saito, S.

2013-12-01

During Ocean Drilling Program (ODP) Leg. 186, two sites (Site 1150 and Site 1151) were drilled on the continental slope of the deep-sea forearc basin of northern Japan. Diatomaceous sediments were recovered Site 1150 (39° 10.9' N, 143° 19.9' E) and Site 1151 (38° 45.1' N, 143° 20.0' E), and the depth of each site is 1181.60 mbsf and 1113.60 mbsf, respectively. This area is under the influence of the Oyashio current and is one of the highly bio-productive regions of the North Pacific Ocean (Motoyama et al., 2004). The combination of high productivity and active tectonic deformation that often caused high rate accumulating of fossil and organic rich sediments. The onboard results of porosity measurements show high value (50-70 %) down to 1000 mbsf, and obviously higher than nearby subduction trench, Nankai Trough (Taylor and Fisher, 1993). There is a possibility that diatomaceous shell keep a frame structure from effective stress and load pressure. On another drilling site result, DSDP (Deep Sea Drilling Project) Leg. 19 located 60 km to the north of ODP sites, was reported high value of porosity, but recognized only shallow range (>500 mbsf) (Shephard and Bryant, 1980). We focused on the relationships between physical property, microstructure, and logging data at deep range(~1000 mbsf). We picked 14 samples to observe microstructure using SEM and measure permeability using flow-ump approach (1.5-4.5 MPa). Logging data were collected using wireline logging (Sacks and Suyehiro, 2003). Based on these results, it is expected that microstructure and logging can be integrated into a general model of core-log correlation. We observed many pores in and around diatom fossils using SEM even in the sample from deeper than 1000 mbsf, and measured pore size distribution and permeability at each depth. Generally, porosity decreases by effective stress and load pressure, and permeability also decrease with down hole. In this site, we recognized down hole decreases of pore space and preservations of diatom shell by using SEM. However, measured permeability displayed subtle patterns in downhole. These results can be considered that intact diatom shells don't always contribute to permeability, while fractured fabrics play good correlation with consolidation. Furthermore, correlations between water content ratio, permeability, and ithostratigraphic variance can be considered as a good index for hydraulic sedimental conditions. In this presentation, We show results of data integration of lithostratigraphy, measurements values, logging data, and physical properties.

A new approach to Ozone Depletion Potential (ODP) estimation

NASA Astrophysics Data System (ADS)

Portmann, R. W.; Daniel, J. S.; Yu, P.

2017-12-01

The Ozone Depletion Potential (ODP) is given by the time integrated global ozone loss of an ozone depleting substance (ODS) relative to a reference ODS (usually CFC-11). The ODP is used by the Montreal Protocol (and subsequent amendments) to inform policy decisions on the production of ODSs. Since the early 1990s, ODPs have usually been estimated using an approximate formulism that utilizes the lifetime and the fractional release factor of the ODS. This has the advantage that it can utilize measured concentrations of the ODSs to estimate their fractional release factors. However, there is a strong correlation between stratospheric lifetimes and fractional release factors of ODSs and that this can introduce uncertainties into ODP calculations when the terms are estimated independently. Instead, we show that the ODP is proportional to the average global ozone loss per equivalent chlorine molecule released in the stratosphere by the ODS loss process (which we call the Γ factor) and, importantly, this ratio varies only over a relatively small range ( 0.3-1.5) for ODPs with stratospheric lifetimes of 20 to more than 1,000 years. The Γ factor varies smoothly with stratospheric lifetime for ODSs with loss processes dominated by photolysis and is larger for long-lived species, while stratospheric OH loss processes produce relatively small Γs that are nearly independent of stratospheric lifetime. The fractional release approach does not accurately capture these relationships. We propose a new formulation that takes advantage of this smooth variation by parameterizing the Γ factor using ozone changes computed using the chemical climate model CESM-WACCM and the NOCAR two-dimensional model. We show that while the absolute Γ's vary between WACCM and NOCAR models, much of the difference is removed for the Γ/ΓCFC-11 ratio that is used in the ODP formula. This parameterized method simplifies the computation of ODPs while providing enhanced accuracy compared to the fractional release method and it can be used to estimate many ODPs given information on chemical reaction rates and photolysis processes.

Applications for evaluation of physical properties - An example of siliceous rock permeability -

NASA Astrophysics Data System (ADS)

Ojima, T.

2015-12-01

ODP Leg. 186, two sites (Site 1150 and Site 1151) were drilled on the continental slope of the deep-sea forearc basin of northern Japan. Diatomaceous sediments were recovered Site 1150 and Site 1151, and the depth of each site is 1181.60 mbsf and 1113.60 mbsf, respectively. This area is under the influence of the Oyashio current and is one of the highly bio-productive regions of the North Pacific Ocean (Motoyama et al., 2004). The combination of high productivity and active tectonic deformation that often caused high rate accumulating of fossil and organic rich sediments. Likewise, IODP Exp. 341 was implemented on off South Alaska. Pelagic and MTD 's layer were recognized with IRD(Ice Rafted Debris). In Tohoku, The onboard results of porosity measurements show high value (50-70 %) down to 1000 mbsf, and obviously higher than nearby subduction trench, Nankai Trough (Taylor and Fisher, 1993). There is a possibility that diatomaceous shell keep a frame structure from effective stress and load pressure. On another drilling site result, DSDP Leg. 19 located 60 km to the north of ODP sites, was reported high value of porosity, but recognized only shallow range (>500 mbsf) (Shephard and Bryant, 1980). Also, South Alaska sediments show high sedimentation rate and cyclic MTD's Layer. Permeability was lower than Tohoku sediments in spite of upper depth. We focused on the relationships between physical property, microstructure, and logging data at deep range(-1000 mbsf). Logging data were collected using wireline logging (Sacks and Suyehiro, 2003; IODP Prel. Rept., 341., 2014). Based on these results, it is expected that microstructure and logging can be integrated into a general model of core-log correlation. In this presentation, We show results of microstructure using SEM, measured physical properties, and wireline logging data, respectively.

A Brunhes-Matuyama polarity transition record from anoxic sediments in the South Atlantic (Ocean Drilling Program Hole 1082C)

NASA Astrophysics Data System (ADS)

Yamazaki, T.; Oda, H.

2001-08-01

A paleomagnetic study was performed on Hole 1082C sediment cores taken during the Ocean Drilling Program (ODP) Leg 175 in the South Atlantic in order to obtain a high-resolution Brunhes-Matuyama (B/M) polarity transition record. An average sedimentation rate was as high as 10 cm/kyr. The cores consist of strongly anoxic sediments, which is common for the areas of large material supply. Anoxic sediments, which are geochemically quite active, were considered to be unsuitable for studies on detailed behavior of the geomagnetic field such as polarity transitions. For global site distribution, however, it is necessary to make efforts to retrieve paleomagnetic records from such sediments. A continuous record of directional changes around the transition was obtained from U-channel samples after cleaning by stepwise alternating-field (AF) demagnetization. Consistency of the record was checked using discrete samples taken from the other half of the cores. The coring-induced magnetic overprint of radial-inward direction, which has often been reported from ODP piston-cores, was negligibly small in our cores. Relative paleointensity variation was estimated from remanent intensities of the discrete samples normalized by artificial remanences. Our record shows following features of the B/M transition similar to those already reported by previous studies. A zone of large directional fluctuations with low paleointensities occurs just before the main transition (788 to 795 ka based on the oxygen-isotope stratigraphy), which would correspond to the "precursor" of Hartl and Tauxe (1996). The virtual geomagnetic poles (VGPs) at the precursor lie along the so-called preferred longitudinal bands over the north-south Americas and Australia-east Asia. After the main transition from the reversed to normal polarity, VGPs stayed in the middle-to-high latitudes over the North America with an intermediate paleointensity for about 5~kyrs, and then moved in the vicinity of the North Pole with full recovery of intensity. Such behavior was reported by Oda et al. (2000). These similarities suggest that the anoxic sediments at Site 1082 could record the behavior of the geomagnetic field rather faithfully, although the remanence may be of chemical origin.

Late Oligocene decoupling of temperature and pCO2: Insights from TEX86 paleothermometry

NASA Astrophysics Data System (ADS)

O'Brien, C. L.; Pagani, M.

2016-12-01

Current paleo-proxy reconstructions for the late Oligocene ( 28-23 Ma) indicate a decoupling of temperature and pCO2. Specifically, benthic oxygen isotope data suggest either stable conditions or warming/deglaciation, while alkenone-based pCO2 estimates indicate a decline from 700 to 400 ppm. Existing sea surface temperature (SST) proxy estimates for this interval are sparse and the appearance of decoupling could be fallacious. Using late Oligocene marine sediments from a range of oceanographic and latitudinal settings, in particular Atlantic Ocean sites ODP 929A (5°N), DSDP 608 (42°N) and DSDP 516F (30°S), we are applying the TEX86 paleothermometer to provide improved constraints on late Oligocene warmth. Thought to originate mainly from planktonic, ammonia-oxidizing Thaumarchaeota, the sedimentary TEX86 signal is complicated by potential influences from additional sources and non-thermal effects (e.g., water chemistry, nutrient dynamics, growth stage and ecology). Thus, we are simultaneously testing assumptions regarding the fidelity of the TEX86 paleo-SST proxy. Our new TEX86H-SST data from Atlantic site ODP 929A indicate stable SSTs in the tropics (often reflective of global conditions) during the late Oligocene, with no reduction in SST coincident with declining pCO2 during the period 28-24 Ma. Importantly, TEX86H-SST data show a lack of coherence with latitude exemplified by similar stable SSTs, 28°C, at tropical and southern mid-latitude Atlantic sites ODP 929 and DSDP 516F, respectively. This absence of a decrease in SST with increasing site latitude suggests that additional non-thermal factors may be influencing the TEX86 signal at certain locations and/or a need for regional-based TEX86-SST calibrations. Indeed, if our tropical TEX86-SST reconstructions ( 28°C) are valid then this would imply the late Oligocene tropical Atlantic was no warmer than the Pliocene, contradicting multiple lines of evidence that the world was warmer (e.g., higher pCO2, lighter benthic δ18O values and lower ice volume). We shall critically evaluate the implications of our TEX86 data with respect to both (1) late Oligocene climate dynamics and (2) the validity of the TEX86-SST proxy across multiple late Oligocene ocean sites.

Monocular Deprivation in Adult Mice Alters Visual Acuity and Single-Unit Activity

ERIC Educational Resources Information Center

Evans, Scott; Lickey, Marvin E.; Pham, Tony A.; Fischer, Quentin S.; Graves, Aundrea

2007-01-01

It has been discovered recently that monocular deprivation in young adult mice induces ocular dominance plasticity (ODP). This contradicts the traditional belief that ODP is restricted to a juvenile critical period. However, questions remain. ODP of young adults has been observed only using methods that are indirectly related to vision, and the…

Applications of Ontology Design Patterns in Biomedical Ontologies

PubMed Central

Mortensen, Jonathan M.; Horridge, Matthew; Musen, Mark A.; Noy, Natalya F.

2012-01-01

Ontology design patterns (ODPs) are a proposed solution to facilitate ontology development, and to help users avoid some of the most frequent modeling mistakes. ODPs originate from similar approaches in software engineering, where software design patterns have become a critical aspect of software development. There is little empirical evidence for ODP prevalence or effectiveness thus far. In this work, we determine the use and applicability of ODPs in a case study of biomedical ontologies. We encoded ontology design patterns from two ODP catalogs. We then searched for these patterns in a set of eight ontologies. We found five patterns of the 69 patterns. Two of the eight ontologies contained these patterns. While ontology design patterns provide a vehicle for capturing formally reoccurring models and best practices in ontology design, we show that today their use in a case study of widely used biomedical ontologies is limited. PMID:23304337

Micropulse laser for persistent optic disc pit maculopathy. A case report.

PubMed

Valdés-Lara, Carlos Andrés; Crim, Nicolás; García-Aguirre, Gerardo; Lule, Ismael Ávila; Morales-Cantón, Virgilio

2018-06-01

Optic disc pits (ODP) are rare and congenital anomalies of the optic disc, sometimes remaining asymptomatic. However, serous macular detachment or optic disc maculopathy is the most common complication, causing significant visual deterioration, without a current consensus about treatment. We describe a case of ODP maculopathy that was treated successfully with micropulse laser. A patient with ODP maculopathy remained with macular serous detachment after nine months of follow up after pars plana vitrectomy. Subthreshold micropulse laser was used to treat macular serous detachment, achieving a significant improvement in central macular thickness after one session. Subthreshold micropulse laser is designed to stimulate the retinal pigment epithelium without damage to the photoreceptors, resulting in absorption of subretinal and intraretinal fluid. Macular serous detachment in patients with ODP requires a prompt diagnosis and treatment to avoid damage to photoreceptors. Subthreshold micropulse laser is a potential treatment for eyes with ODP and macular serous detachment complication.

Australasian microtektites and associated impact ejecta in the South China Sea and the Middle Pleistocene supereruption of Toba

NASA Astrophysics Data System (ADS)

Glass, Billy P.; Koeberl, Christian

2006-02-01

Australasian microtektites were discovered in Ocean Drilling Program (ODP) Hole 1143A in the central part of the South China Sea. Unmelted ejecta were found associated with the microtektites at this site and with Australasian microtektites in Core SO95-17957-2 and ODP Hole 1144A from the central and northern part of the South China Sea, respectively. A few opaque, irregular, rounded, partly melted particles containing highly fractured mineral inclusions (generally quartz and some K feldspar) and some partially melted mineral grains, in a glassy matrix were also found in the microtektite layer. The unmelted ejecta at all three sites include abundant white, opaque grains consisting of mixtures of quartz, coesite, and stishovite, and abundant rock fragments which also contain coesite and, rarely, stishovite. This is the first time that shock-metamorphosed rock fragments have been found in the Australasian microtektite layer. The rock fragments have major and trace element contents similar to the Australasian microtektites and tektites, except for higher volatile element contents. Assuming that the Australasian tektites and microtektites were formed from the same target material as the rock fragments, the parent material for the Australasian tektites and microtektites appears to have been a fine-grained sedimentary deposit. Hole 1144A has the highest abundance of microtektites (number/cm2) of any known Australasian microtektite-bearing site and may be closer to the source crater than any previously identified Australasian microtektite-bearing site. A source crater in the vicinity of 22° N and 104° E seems to explain geographic variations in abundance of both the microtektites and the unmelted ejecta the best; however, a region extending NW into southern China and SE into the Gulf of Tonkin explains the geographic variation in abundance of microtektites and unmelted ejecta almost as well. The size of the source crater is estimated to be 43 ± 9 km based on estimated thickness of the ejecta layer at each site and distance from the proposed source. A volcanic ash layer occurs just above the Australasian microtektite layer, which some authors suggest is from a supereruption of the Toba caldera complex. We estimate that deposition of the ash occurred ˜800 ka ago and that it is spread over an area of at least 3.7 × 107 km2.

A multi-proxy isotope study (δ41K, δ26Mg, 87Sr/86Sr) of low-temperature oceanic crust alteration: the Troodos Ophiolite and Ocean Drilling Program Hole 801C

NASA Astrophysics Data System (ADS)

Santiago Ramos, D. P.; Higgins, J. A.

2017-12-01

Low-temperature alteration of oceanic crust plays an important role in a number of geochemical cycles, thus modulating the chemical composition of the oceans. In particular, it has been established that low-temperature (<150oC) alteration of basalt is a major sink of seawater potassium. However, little is known about the effects of this process on the potassium isotope composition of seawater, which is 0.5‰ enriched relative to bulk silicate Earth (δ41KBSE=-0.54‰). Here we measure a number of isotope systems (δ41K, δ26Mg, 87Sr/86Sr) in both host rock and vein material from the upper volcanic section of Cretaceous (Troodos Ophiolite) and Jurassic (ODP 801C) oceanic crust using a MC-ICP-MS. The goal is to estimate the K isotopic fractionation associated with basalt alteration in low-temperature conditions, and how it might affect the K isotope enrichment of seawater relative to BSE. We find that marine hydrothermal samples from Troodos and ODP site 801C are enriched in potassium relative to the unaltered glass compositions and have δ41K values both higher and lower than BSE, ranging from -0.45‰ to -0.69‰ (n = 9) and -0.32‰ to -0.71‰ (n = 5), respectively. The low measured δ41K values could represent 1) fractionation (α<1) of K isotopes during uptake from seawater (δ41KSW 0‰), or 2) remobilized mantle-sourced K (δ41KBSE=-0.54‰) from deeper within the ophiolite sequence. Measurements of δ26Mg (n=15) and 87Sr/86Sr (n=12) in these samples yield enriched values relative to bulk silicate Earth, suggesting that alteration of oceanic crust likely happened under high water-to-rock ratios in both Troodos and ODP 801C, and that the added potassium is seawater-sourced. We thus suggest that the isotopically light δ41K values measured in both sites are associated with the formation of secondary clays enriched in the 39K isotope. This light isotope enrichment could be intensified if seawater K sourcing is a diffusion-limited process, as aqueous potassium diffusion has been associated with K isotope fractionations between 0.9967 and 0.9984. Our results indicate that the uptake of potassium in altered oceanic crust could be responsible, in part, for the observed K isotope enrichment of seawater relative to bulk silicate Earth.

In-situ petrophysical properties of hotspot volcanoes. Results from ODP Leg 197, Detroit Seamount and HSDP II borehole, Hawaii

NASA Astrophysics Data System (ADS)

Kock, I.; Pechnig, R.; Buysch, A.; Clauser, C.

2003-04-01

During ODP Leg 197 an extensive logging program was run on Site 1203, Detroit Seamount. This seamount is part of the Emperor seamount chain, a continuation of the Hawaiian volcanic chain. Standard ODP/LDEO logging tool strings were used to measure porosity, density, resistivity, p- and s-wave velocities and gamma ray activity. The FMS-tool yielded detailed high resolution resistivity images of the borehole wall. By interpretation and statistical analysis of the logging parameters a petrophysical classification of the drilled rock content could be derived. The pillow lava recovered in the cores exhibits low porosity, low resistivity and high density. This indicates no or very little vesicles in the non-fractured rock unit. Compared to the pillow basalts, subaerial basalts show increasing porosity, gamma ray and potassium content and decreasing density, resistivity and velocity. A basalt with no or little vesicles and a basalt with average or many vesicles can clearly be distinguished. The volcaniclastics show lower resistivity, lower sonic velocities, higher porosities and lower densities than the basalts. Three different rock types can be distinguished within the volcaniclastics: Tuffs, resedimented tephra and breccia. The tuff shows medium porosity and density, low gamma ray and potassium content. The log responses from the resedimented tephra suggest that the tephra is more easily altered than the tuff. The log responses from the breccia lie between the tuff and tephra log responses, but the breccia can clearly be identified in the FMS borehole images. A similar rock content was found in the Hawaiian Scientific Drilling Project borehole. Gamma ray activity, electrical resistivity and sonic velocity were measured down to 2700 mbsl.. Compared to the 72-76 Ma old Detroit seamount basalts, the HSDP subaerial and submarine lava flows show a significant lower gamma ray activity, while sonic velocity and electrical resistivity are comparable. Deviations between the gamma ray activity might be due to the different primary compositions of the melt or to long lasting low temperature alteration. Investigations on this topic are in progress.

Untangling Magmatic Processes and Hydrothermal Alteration of in situ Superfast Spreading Ocean Crust at ODP/IODP Site 1256 with Fuzzy c-means Cluster Analysis of Rock Magnetic Properties

NASA Astrophysics Data System (ADS)

Dekkers, M. J.; Heslop, D.; Herrero-Bervera, E.; Acton, G.; Krasa, D.

2014-12-01

Ocean Drilling Program (ODP)/Integrated ODP (IODP) Hole 1256D (6.44.1' N, 91.56.1' W) on the Cocos Plate occurs in 15.2 Ma oceanic crust generated by superfast seafloor spreading. Presently, it is the only drill hole that has sampled all three oceanic crust layers in a tectonically undisturbed setting. Here we interpret down-hole trends in several rock-magnetic parameters with fuzzy c-means cluster analysis, a multivariate statistical technique. The parameters include the magnetization ratio, the coercivity ratio, the coercive force, the low-field susceptibility, and the Curie temperature. By their combined, multivariate, analysis the effects of magmatic and hydrothermal processes can be evaluated. The optimal number of clusters - a key point in the analysis because there is no a priori information on this - was determined through a combination of approaches: by calculation of several cluster validity indices, by testing for coherent cluster distributions on non-linear-map plots, and importantly by testing for stability of the cluster solution from all possible starting points. Here, we consider a solution robust if the cluster allocation is independent of the starting configuration. The five-cluster solution appeared to be robust. Three clusters are distinguished in the extrusive segment of the Hole that express increasing hydrothermal alteration of the lavas. The sheeted dike and gabbro portions are characterized by two clusters, both with higher coercivities than in lava samples. Extensive alteration, however, can obliterate magnetic property differences between lavas, dikes, and gabbros. The imprint of thermochemical alteration on the iron-titanium oxides is only partially related to the porosity of the rocks. All clusters display rock magnetic characteristics in line with a stable NRM. This implies that the entire sampled sequence of ocean crust can contribute to marine magnetic anomalies. Determination of the absolute paleointensity with thermal techniques is not straightforward because of the propensity of oxyexsolution during laboratory heating and/or the presence of intergrowths. The upper part of the extrusive sequence, the granoblastic portion of the dikes, and moderately altered gabbros may contain a comparatively uncontaminated thermoremanent magnetization.

40 CFR Appendix B to Subpart A of... - Class II Controlled Substances a

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 17 2010-07-01 2010-07-01 false Class II Controlled Substances a B..., Subpt. A, App. B Appendix B to Subpart A of Part 82—Class II Controlled Substances a Controlled... the highest ODP, and the lower value is the estimate of the ODP of the isomer with the lowest ODP...

Correlation of the oldest Toba Tuff to sediments in the central Indian Ocean Basin

NASA Astrophysics Data System (ADS)

Pattan, J. N.; Shyam Prasad, M.; Babu, E. V. S. S. K.

2010-08-01

We have identified an ash layer in association with Australasian microtektites of ˜0.77 Ma old in two sediment cores which are ˜450 km apart in the central Indian Ocean Basin (CIOB). Morphology and chemical composition of glass shards and associated microtektites have been used to trace their provenance. In ODP site 758 from Ninetyeast Ridge, ash layer-D (13 cm thick, 0.73-0.75 Ma) and layer-E (5 cm thick, 0.77-0.78 Ma) were previously correlated to the oldest Toba Tuff (OTT) eruptions of the Toba caldera, Sumatra. In this investigation, we found tephra ˜3100 km to the southwest of Toba caldera that is chemically identical to layer D of ODP site 758 and ash in the South China Sea correlated to the OTT. Layer E is not present in the CIOB or other ocean basins. The occurrence of tephra correlating to layer D suggests a widespread distribution of OTT tephra (˜3.6 × 107 km2), an ash volume of at least ˜1800 km3, a total OTT volume of 2300 km3, and classification of the OTT eruption as a super-eruption.

Structural characteristics of the acquired optic disc pit and the rate of progressive retinal nerve fiber layer thinning in primary open-angle glaucoma.

PubMed

Lee, Seung Hyen; Lee, Eun Ji; Kim, Tae-Woo

2015-10-01

The optic disc pit (ODP) has been considered a region of localized susceptibility to the damage of glaucoma. To determine whether the rate of retinal nerve fiber layer (RNFL) thinning differs according to the presence and structural characteristics of an ODP in primary open-angle glaucoma. We performed a prospective case-control study that included 163 eyes with primary open-angle glaucoma (83 with an ODP and 80 without an ODP) from Glaucoma Clinic of Seoul National University Bundang Hospital. Participants were enrolled from the ongoing Investigating Glaucoma Progression Study from January 1, 2012, through May 31, 2014. Mean (SD) follow-up was 3.32 (0.49) years (through May 31, 2014). Optic nerve heads underwent swept-source optical coherence tomography (OCT) to determine the presence of focal lamina cribrosa alteration and its structural characteristics. Eyes with and without photographic ODPs and corresponding microscopic laminar alterations were assigned to the ODP and non-ODP groups, respectively. The rates of progressive thinning of global and 6 sectoral spectral-domain OCT RNFL thicknesses were determined by linear regression and compared between the 2 groups. We used a general linear model to determine the factors associated with the rate of RNFL thinning; data obtained from September 21, 2009, through May 31, 2014, were used to calculate the rate of RNFL thinning. The relationship between the presence and structural characteristics of ODPs and the rate of progressive OCT RNFL thinning. Thinning of the RNFL was faster in the ODP group than in the non-ODP group in the global (mean [SD], -1.44 [1.31] vs -0.93 [1.10] [95% CI, -0.97 to -0.19] μm/y; P = .008), temporoinferior (mean [SD], -4.17 [4.15] vs -1.97 [3.26] [95% CI, -3.36 to -1.04] μm/y; P < .001), and temporal (mean [SD], -1.92 [2.62] vs -0.89 [1.62] [95% CI, -1.70 to -0.35] μm/y; P = .003) sectors. The rate of RNFL thinning was maximum in the temporoinferior sector (mean [SD], -4.17 [4.15] μm/y) and corresponded to the frequency distribution of ODPs. Regression analysis revealed that faster global RNFL thinning was related to a higher untreated intraocular pressure (β = -0.07; 95% CI, -0.11 to -0.03; P = .001), episodes of disc hemorrhage (β = -0.74; 95% CI, -1.79 to 0.31; P = .003), the presence of β-zone parapapillary atrophy (β = -0.47; 95% CI, -1.13 to 0.20; P = .02), and the presence of ODPs (β = -0.41; 95% CI, -1.14 to 0.32; P = .02). The maximum rate of RNFL thinning was associated with higher untreated intraocular pressure (β = -0.24; 95% CI, -0.35 to -0.13; P < .001), disc hemorrhage (β = -1.54; 95% CI, -2.88 to -0.19; P < .001), and the presence (β = -1.04; 95% CI, -2.14 to 0.07; P = .004), far-peripheral location (β = -1.75; 95% CI, -3.05 to -0.46; P = .008), and partial-thickness depth (β = -1.45; 95% CI, -2.75 to -0.16; P = .03) of an ODP. The presence and structural characteristics of ODPs were associated with global and focal progression as assessed by the rate of OCT RNFL thinning. The assessment of ODP structure using swept-source OCT may help to predict the location of future progression.

Deep water dissolution in Marine Isotope Stage 3 from the northern South China Sea

NASA Astrophysics Data System (ADS)

Huang, B.

2015-12-01

The production, transport, deposition, and dissolution of carbonate profoundly implicate the global carbon cycle affect the inventory and distribution of dissolved organic carbon (DIC) and alkalinity (ALK), which drive atmospheric CO2 change on glacial-interglacial timescale. the process may provide significant clues for improved understanding of the mechanisms that control the global climate system. In this study, we calculate and analyze the foraminiferal dissolution index (FDX) and the fragmentation ratios of planktonic foraminifera over 60-25 ka based on samples from 17924 and ODP 1144 in the northeastern South China Sea (SCS) to reconstruct the deep water carbonate dissolution during Marine Isotope Stage 3 (MIS 3). Result shows that the dissolution of carbonate increases gradually at 17924 but keeps stable at ODP 1144. The changes of FDX coincidence with that of fragmentation ratios at 17924 and ODP 1144 suggest both indexes can be used as reliable dissolving proxies of planktonic foraminifera. Comparing FDX and fragmentation ratios at both sites, we find the FDX and fragmentation ratios at 17924 are higher than those at 1144, indicating that carbonate dissolution is intenser in 17924 core during MIS 3. The increasing total percentage of both N. dutertrei and G. bulloides during MIS 3 reveals the rising primary productivity that may lead to deep water [CO32-] decrease. The slow down of thermohaline circulation may increase deep water residence time and accelerate carbonate dissolution. In addition, the covering of ice caps, iron supply and increased surface-water stratification also contribute to atmosphere CO2 depletion and [CO32-] decrease in deep water. In the meanwhile, regression result from colder temperature increases the input of ALK and DIC to the deep ocean and deepens the carbonate saturation depth, which makes the deep water [CO32-] rise. In ODP Site 1144, the decrease in [CO32-] caused by more CO2 restored in deep water is equal to the increase in [CO32-] because of regression, so dissolution keeps steady. However, [CO32-] is probably more strongly controlled by regression, the decrease in [CO32-] result from more CO2 restored in deep water overwhelms the increase in [CO32-] due to regression at 17924, so more carbonate dissolved from MIS 3 to the Last Glacial Maximum (LGM).

A Comparison of Paleomagnetic Secular Variation during MIS 7-10 between the Bering Sea (IODP Ex. 323) and North Atlantic Ocean (ODP Leg 172): Implications for the space/time pattern of field and environmental variability (Invited)

NASA Astrophysics Data System (ADS)

Lund, S.; Okada, M.; Acton, G.; Clement, B. M.; Stoner, J. S.; Platzman, E. S.

2013-12-01

Detailed records of Brunhes paleomagnetic secular variation (PSV) during Marine Isotope Stages (MIS) 7-10 have been recovered from four IODP Ex. 323 sites in the Bering Sea (U1339, U1343-U1345) and four ODP Leg 172 sites from the subtropical North Atlantic Ocean (1060-1063). Reproducible records of PSV (both directions and paleointensity) have been recovered from three or more holes at each site and correlated among the four independent sites in each region. These PSV records provide an unprecedented database for considering patterns of long-term secular variation and evidence for excursional field behavior on a larger than individual regional scale. We will present reproducible evidence for sustained long-term secular variation in each region and assess the extent to which they may be interrelated. We have identified the times of magnetic field excursions 7α, 7β, 8α, 9α, and 9β in the Atlantic records and correlated those times to the Bering Sea records. There are no true excursions in the Bering Sea at those times, but several of these intervals mark the most anomalous field behavior in the Bering Sea during MIS 7-10. In both regions, the PSV also serves as a high-resolution chronostratigraphic tool for regional correlation of environmental variability. Both regions show clear, reproducible evidence among the sites for synchronous millennial-scale environmental variability that has not been diagnosed previously.

``Out To Sea: Life as a Crew Member Aboard a Geologic Research Ship'' - Production of a Video and Teachers Guide.

NASA Astrophysics Data System (ADS)

Rack, F. R.; Tauxe, K.

2004-12-01

In May 2002, Joint Oceanographic Institutions (JOI) received a proposal entitled "Motivating Middle School Students with the JOIDES Resolution", from a middle school teacher in New Mexico named Katie Tauxe. Katie was a former Marine Technician who has worked aboard the R/V JOIDES Resolution in the early years of the Ocean Drilling Program (ODP). She proposed to engage the interest of middle school students using the ODP drillship as the centerpiece of a presentation focused on the lives of the people who work aboard the ship and the excitement of science communicated through an active shipboard experience. The proposal asked for travel funds to and from the ship, the loan of video camera equipment from JOI, and a small amount of funding to cover expendable supplies, video editing, and production at the local Public Broadcasting Station in Los Alamos, NM. Katie sailed on the transit of the JOIDES Resolution through the Panama Canal, following the completion of ODP Leg 206 in late 2002. This presentation will focus on the outcome of this video production effort, which is a 19 minute-long video entitled "Out to Sea: Life as a Crew Member Aboard a Geologic Research Ship", and a teacher's guide that can be found online.

Climate and Biota across the Eocene-Oligocene transition at Site 1090: recent advances on calcareous nannofossils as paleoclimatic and dissolution proxy

NASA Astrophysics Data System (ADS)

Pea, Laura; Fioroni, Chiara; Villa, Giuliana; Persico, Davide; Bohaty, Steve

2010-05-01

The Eocene-Oligocene transition represents the biggest biotic turnover in the Cenozoic, involving both terrestrial and marine realms. In this study we present the results obtained by a quantitative analysis of late Eocene-early Oligocene (35.5- 33.1 Ma) calcareous nannofossil assemblages from ODP Site 1090 Hole B (Leg 177). This Hole is located on the southern flank of the Agulhas Ridge on the Subantarctic sector of the Atlantic Ocean (42°54'S), and lies along the boundary between the North Atlantic Deep Water and the Circumpolar Deep Water. Thanks to its position above the Carbonate Compensation Depth (3702 m), the nannofossil assemblage preservation is from poor to good in most of the section, even thought some intervals are barren. A well-preserved magnetostratigraphic signal along all of the section and nannofossil biostratigraphy provided the time framework essential for interpreting the assemblage variations. Within a high resolution biostratigraphic framework and through the comparison with bulk oxygen and carbon isotope datasets we attempt to reconstruct sea surface water temperature and trophic conditions, aimed to a late Eocene - early Oligocene paleoceanographic reconstruction for the South Atlantic. A marked change in the nannofossil assemblages is associated with the Oi-1 event: a nonlinear increase of cool-water taxa gives evidence as the evolution of this climatic event is more complex than previously estimated by calcareous nannofossils in the Southern Ocean (Villa et al., 2008). In fact cool-water taxa variation trend likely reflects the two distinct shifts (Step 1 and Step) recognised by Coxall et al. (2005) within the oxygen isotope shift .Step 1 falls in the uppermost part of magnetochron C13r, while the end of step 2 correlates with the base of Chron C13n (Channell et al., 2005). Furthermore, changes in nannofossil abundance and preservation suggest CCD depth fluctuations, showing a deepening near the Eocene/Oligocene boundary, as previously suggested (Coxall et al., 2005). Site 1090 is located at 3702 m water depth, currently lays above the CCD (Gersonde et al., 1999), but it was probably close or below it during the Eocene until its deepening at the Oi-1 event; this might explain the presence of numerous barren samples along the section and a major dissolution event occurring just before Step 1. References Channell, J.E.T., Galeotti, S., Martin, E.E., Billups, K., Scher, H., Stoner, J.S., 2002. Eocene to Miocene magnetostratigraphy, biostratigraphy, and chemostratigraphy at ODP Site 1090 (sub-Antarctic South Atlantic). Geological Society of America Bulletin, 115, 607-623. Coxall H.,, Wilson P.A., Palike H., Lear C.H., Backman J.(2005). Rapid stepwise onset of Antarctic glaciation and deeper calcite compensation in the Pacific Ocean. Nature, 433 6 January 2005. Gersonde, R., Hodell, D.A., Blum, P., et al., 1999b. Proc. ODP Init. Rep. 177 [Online]. Available from World Wide Web: http://www-odp.tamu.edu/publications/177_IR/177toc.htm. Villa G., Fioroni C., Pea L., Bohaty S.M., Persico D., 2008. Middle Eocene - Late Oligocene climate variability: Calcareous Nannofossil response at Kerguelen Plateau, Site 748. Mar. Micropaleont., 69, 173-192.

The Impact of the Latest Danian Event on Planktic Foraminiferal Faunas at ODP Site 1210 (Shatsky Rise, Pacific Ocean).

PubMed

Jehle, Sofie; Bornemann, André; Deprez, Arne; Speijer, Robert P

2015-01-01

The marine ecosystem has been severely disturbed by several transient paleoenvironmental events (<200 kyr duration) during the early Paleogene, of which the Paleocene-Eocene Thermal Maximum (PETM, ~56 Ma) was the most prominent. Over the last decade a number of similar events of Paleocene and Eocene age have been discovered. However, relatively little attention has been paid to pre-PETM events, such as the "Latest Danian Event" ("LDE", ~62.18 Ma), specifically from an open ocean perspective. Here we present new foraminiferal isotope (δ13C, δ18O) and faunal data from Ocean Drilling Program (ODP) Site 1210 at Shatsky Rise (Pacific Ocean) in order to reconstruct the prevailing paleoceanographic conditions. The studied five-meter-thick succession covers ~900 kyr and includes the 200-kyr-lasting LDE. All groups surface dwelling, subsurface dwelling and benthic foraminifera show a negative δ13C excursion of >0.6‰, similar in magnitude to the one previously reported from neighboring Site 1209 for benthic foraminifera. δ18O-inferred warming by 1.6 to 2.8°C (0.4-0.7‰ δ18O measured on benthic and planktic foraminiferal tests) of the entire water column accompanies the negative δ13C excursion. A well stratified upper ocean directly before and during the LDE is proposed based on the stable isotope gradients between surface and subsurface dwellers. The gradient is less well developed, but still enhanced after the event. Isotope data are supplemented by comprehensive planktic foraminiferal faunal analyses revealing a dominance of Morozovella species together with Parasubbotina species. Subsurface-dwelling Parasubbotina shows high abundances during the LDE tracing changes in the strength of the isotope gradients and, thus, may indicate optimal living conditions within a well stratified surface ocean for this taxon. In addition, distinct faunal changes are reported like the disappearance of Praemurica species right at the base of the LDE and the continuous replacement of M. praeangulata with M. angulata across the LDE.

The Impact of the Latest Danian Event on Planktic Foraminiferal Faunas at ODP Site 1210 (Shatsky Rise, Pacific Ocean)

PubMed Central

Jehle, Sofie; Bornemann, André; Deprez, Arne; Speijer, Robert P.

2015-01-01

The marine ecosystem has been severely disturbed by several transient paleoenvironmental events (<200 kyr duration) during the early Paleogene, of which the Paleocene-Eocene Thermal Maximum (PETM, ~56 Ma) was the most prominent. Over the last decade a number of similar events of Paleocene and Eocene age have been discovered. However, relatively little attention has been paid to pre-PETM events, such as the “Latest Danian Event” ("LDE", ~62.18 Ma), specifically from an open ocean perspective. Here we present new foraminiferal isotope (δ13C, δ18O) and faunal data from Ocean Drilling Program (ODP) Site 1210 at Shatsky Rise (Pacific Ocean) in order to reconstruct the prevailing paleoceanographic conditions. The studied five-meter-thick succession covers ~900 kyr and includes the 200-kyr-lasting LDE. All groups surface dwelling, subsurface dwelling and benthic foraminifera show a negative δ13C excursion of >0.6‰, similar in magnitude to the one previously reported from neighboring Site 1209 for benthic foraminifera. δ18O-inferred warming by 1.6 to 2.8°C (0.4–0.7‰ δ18O measured on benthic and planktic foraminiferal tests) of the entire water column accompanies the negative δ13C excursion. A well stratified upper ocean directly before and during the LDE is proposed based on the stable isotope gradients between surface and subsurface dwellers. The gradient is less well developed, but still enhanced after the event. Isotope data are supplemented by comprehensive planktic foraminiferal faunal analyses revealing a dominance of Morozovella species together with Parasubbotina species. Subsurface-dwelling Parasubbotina shows high abundances during the LDE tracing changes in the strength of the isotope gradients and, thus, may indicate optimal living conditions within a well stratified surface ocean for this taxon. In addition, distinct faunal changes are reported like the disappearance of Praemurica species right at the base of the LDE and the continuous replacement of M. praeangulata with M. angulata across the LDE. PMID:26606656

Resolving the Subsidence Anomaly of the East Tasman Plateau Using New Insights from the Cascade Seamount, Southwest Tasman Sea

NASA Astrophysics Data System (ADS)

Vorsanger, S. L.; Scher, H.; Johnson, S.; Mundana, R.; Sauermilch, I.; Duggan, B.; Whittaker, J. M.

2017-12-01

The Cascade Seamount is a wave-planated feature located on the microcontinent of the East Tasman Plateau (ETP). The minimum subsidence rate of the Seamount and the ETP can be estimated by dividing the present-day depth of the wave-cut surface (640 m) by the age of Cascade Seamount basalts as determined by potassium-argon (K-Ar) dating (33.4 and 36 Ma). This approach yields a subsidence rate of 18 m/Myr. However, significantly more rapid subsidence rates of the East Tasman Plateau (ETP) — upon which the Cascade Seamount rests — since the Eocene-Oligocene transition have been proposed utilizing a nearby sediment core, Ocean Drilling Program (ODP) Site 1172. Late Eocene paleodepths determined by Stickley et al. (2004) using sedimentological and biostratigraphic techniques, indicate a subsidence rate of 85 m/Myr for the ETP. These two results present a paradox, which implies that the ETP subsided at a rate greater than the Seamount itself, over the same time interval. It also implies that the seamount formed above sea level. The subsidence ambiguity may be attributed to the presence of a turbidity current deposit in the sediment core, or uncertainty in the age and/or location of the K-Ar dated basalts of the Cascade Seamount. Statistical analysis of the published grain size measurements will be used to test for the presence of a turbidity current deposit in ODP Site 1172. We will also measure 87Sr/86Sr ratios of marine carbonate samples from conglomerates obtained from the Cascade Seamount during the August 2016 RV Investigator voyage (IN2016_E01) to confirm the age of the wave planated surfaces by Strontium Isotope Stratigraphy. This will allow for a more robust calculation for the subsidence of the ETP which was a critical barrier in the Tasmanian Gateway that allowed for the formation of the Antarctic Circumpolar Current.

The ozone depletion potentials on halocarbons: Their dependence of calculation assumptions

NASA Technical Reports Server (NTRS)

Karol, Igor L.; Kiselev, Andrey A.

1994-01-01

The concept of Ozone Depletion Potential (ODP) is widely used in the evaluation of numerous halocarbons and of their replacement effects on ozone, but the methods, assumptions and conditions used in ODP calculations have not been analyzed adequately. In this paper a model study of effects on ozone of the instantaneous releases of various amounts of CH3CCl3 and of CHF2Cl (HCFC-22) for several compositions of the background atmosphere are presented, aimed at understanding connections of ODP values with the assumptions used in their calculations. To facilitate the ODP computation in numerous versions for the long time periods after their releases, the above rather short-lived gases and the one-dimensional radiative photochemical model of the global annually averaged atmospheric layer up to 50 km height are used. The variation of released gas global mass from 1 Mt to 1 Gt leads to ODP value increase with its stabilization close to the upper bound of this range in the contemporary atmosphere. The same variations are analyzed for conditions of the CFC-free atmosphere of 1960's and for the anthropogenically loaded atmosphere in the 21st century according to the known IPCC 'business as usual' scenario. Recommendations for proper ways of ODP calculations are proposed for practically important cases.

Laparoscopic versus open distal pancreatectomy for nonfunctioning pancreatic neuroendocrine tumors: a large single-center study.

PubMed

Han, Sang Hyup; Han, In Woong; Heo, Jin Seok; Choi, Seong Ho; Choi, Dong Wook; Han, Sunjong; You, Yung Hun

2018-01-01

Pancreatic neuroendocrine tumors (PNETs) account for 1-2% of all pancreatic neoplasms. Nonfunctioning PNETs (NF-PNETs) account for 60-90% of all PNETs. Laparoscopic distal pancreatectomy (LDP) is becoming the treatment of choice for benign lesions in the body and tail of the pancreas. However, LDP has not yet been widely accepted as the gold standard for NF-PNETs. The purpose of this study is to evaluate the clinical and oncologic outcomes after laparoscopic versus open distal pancreatectomy (ODP) for NF-PNETs. Between April 1995 and September 2016, 94 patients with NF-PNETs underwent open or laparoscopic distal pancreatectomy at Samsung Medical Center. Patients were divided into two groups: those who underwent LDP and those who underwent ODP. Both groups were compared in terms of clinical and oncologic variables. LDP patients had a significantly shorter hospital stay compared with ODP patients, amounting to a mean difference of 2 days (p < 0.001). Overall complication rates did not differ significantly between the ODP and LDP groups (p = 0.379). The 3-year overall survival rates in the ODP and LDP groups were 93.7 and 100%, respectively (p = 0.069). In this study, LDP for NF-PNETs had similar oncologic outcomes compared with ODP. In addition, LDP was associated with a shorter hospital stay compared with ODP. Therefore, LDP is a safe and effective procedure for patients with NF-PNETs. A multicenter study and a randomized controlled trial are needed to better assess the clinical and oncologic outcomes.

Sedimentary and Paleoceanographic Responses to the South China Sea Basin Evolution

NASA Astrophysics Data System (ADS)

Jian, Z.; Liu, Z.; Jin, H.; Larsen, H. C.; Alvarez Zarikian, C. A.; Stock, J. M.; Sun, Z.; Klaus, A.

2017-12-01

As the largest marginal sea of the western Pacific, the South China Sea (SCS) has experienced a complete Wilson cycle, which had inevitably exerted a profound impact on the sedimentary environment and ocean circulation. Based on the results of four ODP/IODP expeditions to the SCS since 1999, together with other research data in this region, this study aims to explore the sedimentary and paleoceanographic responses to the tectonic events and basin evolution in the SCS. The early history of the SCS from land to deep sea was revealed by foraminiferal fauna: (1) The SCS evolved from continental shelf to an upper bathyal environment around the Oligocene/Eocene boundary, and significantly deepened at the turn of Oligocene/Miocene; (2) The early Oligocene SCS was deep but its shelf was narrow, evidenced by the Para-Tethys type deep-sea agglutinated benthic foraminifers and abundant transported shallow-water species at ODP Site 1148. Along with the SCS basin formation and the development of this semi-closed basin, the deep-sea benthic foraminiferal δ13C decreased when the Antarctic ice sheet began to reestablish at 14 Ma, the Indonesian Seaway and the southern SCS deep-water channel were closed at 10 Ma, the Luzon arc collided with Taiwan at 6.5 Ma, and the Bashi Strait was restricted at 1.2 Ma. Nd isotopes of shark teeth at ODP Site 1148 also support these inferences. An early to middle Miocene succession of red clay was found at all sites deeper than 3500 m water depth, which may be correlated to a basin-wide event related to deep circulation of oxygenated water from the western Pacific. After the earliest late Miocene carbonate crash, the red clay disappeared while the large carbonate platforms were drowned and remarkably shrank in the SCS. Late Miocene sediments display a succession of hemi-pelagic and turbidite deposits, indicating that the deep basin entered its modern state below the CCD. Frequent turbidites ended when Pliocene growth of deep-sea manganese-nodules reoccurred in the SCS. The data show that the SCS can serve as a natural laboratory to study the relationship between paleoceanographic changes and tectonic events.

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.

Late Cenozoic history of North African climate and vegetation: Orbital and secular changes revealed by leaf-wax biomarkers at multiple ODP sites

NASA Astrophysics Data System (ADS)

Meyers, C.; deMenocal, P. B.; Polissar, P. J.; Tierney, J. E.

2013-12-01

East Africa experienced a large shift towards increasingly arid conditions and expanded C4 grasslands after about 2 Ma, as indicated by multiple terrestrial and marine paleoclimatic and paleontological records. We investigated whether the East African shift towards C4 grasslands was associated with a change in the west African monsoonal response to orbital precession forcing. We analyzed eastern Mediterranean sedimentary leaf wax stable isotopes (δDwax and δ13Cwax) and planktonic foraminifera δ18O from ODP Site 967 at 2.5 kyr resolution from 3.0 - 3.1 Ma and 1.78 - 1.68 Ma, intervals with equal eccentricity forcing that bracket the rise in East African C4 grasslands. Large-amplitude negative excursions occur in δDwax, δ13Cwax, and δ18Oruber during sapropel intervals, consistent with our expectations that these proxies track increased monsoonal rainfall and runoff and more abundant C3 vegetation during wet North African periods. Nannofossil ooze sediments exhibit large positive isotopic excursions, consistent with drier North African conditions. However, average isotopic values are not significantly different for either δDwax or δ13Cwax from 3.0 Ma to 1.7 Ma, suggesting that west African monsoonal precipitation strength and vegetation were similar in North Africa during the East African C4 vegetation expansion. Our calculations of δDwater yield estimates similar to modern precipitation in northeast Africa, and δ13Cwax data indicate that vegetation varied between 70-90% C4 types during both periods. These results suggest that Site 967 primarily records northeast African climate and vegetation, and that East Africa's aridity and C4 vegetation expansion were a regional signal not experienced by northeast Africa. We will place both northeast Africa and East African changes in a long-term context with preliminary results from the last 25 Myr of NW African margin leaf wax δD. Analysis of samples from ODP Sites 659 (18°N, 21°W; W. Saharan margin) and 959 (4°N, 2°W; Gulf of Guinea) will document the Oligocene-present evolution of the aridity and vegetation gradients that characterize northwest Africa today.

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.

Late Paleogene-early Neogene dinoflagellate cyst biostratigraphy of the eastern Equatorial Atlantic

NASA Astrophysics Data System (ADS)

Awad, Walaa K.; Oboh-Ikuenobe, Francisca E.

2018-04-01

Six dinoflagellate cyst biozones (zone 1-zone 5, subzones 1a and 1b) are recognized in the late Paleogene-early Neogene interval of the Ocean Drilling Program (ODP) Site 959 (Hole 959 A), Côte d'Ivoire-Ghana Transform Margin in the eastern Equatorial Atlantic. The biozones are based on palynological analysis of 30 samples covering a 273.2-m interval with generally fair preservation and good to poor recovery. We propose a new age of Late Eocene (Priabonian) for subunit IIB as opposed to the previously published mid-Early Oligocene age (middle Rupelian). This age assignment is mainly based on the presence of Late Eocene marker taxa, such as Hemiplacophora semilunifera and Schematophora speciosa in the lower part of the studied interval. We also document for the first time a hiatus event within dinoflagellate cyst zone 3, based on the last occurrences of several taxa. This interval is assigned to an Early Miocene age and is barren of other microfossils. Furthermore, we propose new last occurrences for two species. The last occurrence of Cerebrocysta bartonensis is observed in the late Aquitanian-early Burdigalian in this study vs. Priabonian-early Rupelian in mid and high latitude regions. Also, the last occurrence of Chiropteridium galea extends to the latest Early Miocene (Burdigalian) in ODP Hole 959 A; this event was previously identified in other studies as Chattian in equatorial regions, and Aquitanian in the Northern Hemisphere mid-latitudes. We suspect that these differences are due to physical (offshore vs. nearshore) and latitudinal locations of the areas studied.

Microfossil evidence for trophic changes during the Eocene-Oligocene transition in the South Atlantic (ODP Site 1263, Walvis Ridge)

NASA Astrophysics Data System (ADS)

Bordiga, M.; Henderiks, J.; Tori, F.; Monechi, S.; Fenero, R.; Legarda-Lisarri, A.; Thomas, E.

2015-09-01

The biotic response of calcareous nannoplankton to environmental and climatic changes during the Eocene-Oligocene transition was investigated at a high resolution at Ocean Drilling Program (ODP) Site 1263 (Walvis Ridge, southeast Atlantic Ocean) and compared with a lower-resolution benthic foraminiferal record. During this time interval, global climate, which had been warm under high levels of atmospheric CO2 (pCO2) during the Eocene, transitioned into the cooler climate of the Oligocene, at overall lower pCO2. At Site 1263, the absolute nannofossil abundance (coccoliths per gram of sediment; N g-1) and the mean coccolith size decreased distinctly after the E-O boundary (EOB; 33.89 Ma), mainly due to a sharp decline in abundance of large-sized Reticulofenestra and Dictyococcites, occurring within a time span of ~ 47 kyr. Carbonate dissolution did not vary much across the EOB; thus, the decrease in abundance and size of nannofossils may reflect an overall decrease in their export production, which could have led to variations in the food availability for benthic foraminifers. The benthic foraminiferal assemblage data are consistent with a global decline in abundance of rectilinear species with complex apertures in the latest Eocene (~ 34.5 Ma), potentially reflecting changes in the food source, i.e., phytoplankton. This was followed by a transient increased abundance of species indicative of seasonal delivery of food to the sea floor (Epistominella spp.; ~ 33.9-33.4 Ma), with a short peak in overall food delivery at the EOB (buliminid taxa; ~ 33.8 Ma). Increased abundance of Nuttallides umbonifera (at ~ 33.3 Ma) indicates the presence of more corrosive bottom waters and possibly the combined arrival of less food at the sea floor after the second step of cooling (Step 2). The most important changes in the calcareous nannofossil and benthic communities occurred ~ 120 kyr after the EOB. There was no major change in nannofossil abundance or assemblage composition at Site 1263 after Step 2 although benthic foraminifera indicate more corrosive bottom waters during this time. During the onset of latest-Eocene-earliest-Oligocene climate change, marine phytoplankton thus showed high sensitivity to fast-changing conditions as well as to a possibly enhanced, pulsed nutrient supply and to the crossing of a climatic threshold (e.g., pCO2 decline, high-latitude cooling and changes in ocean circulation).

Sediment compaction in deepwater basin of the South China Sea: estimation from ODP 184 and IODP 349 drilling well data.

NASA Astrophysics Data System (ADS)

Tuoyu, W.; Xie, Y.

2017-12-01

Abnormal compaction in deepwater basins not only cause serious soft sediment deformation, but also significantly affect the safety of the drilling campaign. Therefore, study the compaction condition in the sediments would be an important task in the deepwater basin and associate with the environment variation. We analyze the drilling data from the ODP Leg 184 Site 1144, 1146, 1148 and the IODP Leg 349 Site U1431, U1432, U1433, U1435 to study the sediment compaction and controls in the northern South China Sea. We have found the sedimentation rate, sediment content, distribution area and buried depth control the sediment compaction in deepwater basin of the South China Sea. Among all the factors, the sediment content is the most important factor. The fitted normal compacted coefficients and the mudline porosity for interval 50 m shows disciplinary variation versus depth. The pore pressure predicted from different fitted results shows different overpressure situation. The normal compaction trend from Site 1144 reflects the porosity variation trend in stable deposition basins in the northern South China Sea. The predicted pore pressure shows overpressure at Site 1144, which is attributed to compaction disequilibrium. Nevertheless, the mixed lithology column may influence the predicted overpressure at Site 1148, which is responsible for the confusing result. Above all. we find that sediment compaction should be act as a proxy for pore pressure in the deepwater basin of the South China Sea. The study will help us to nature of sedimentation in the deepwater basin set up and can be used as analog for older sediments deposited in the similar kind of depositional environment in deepwater basin of the South China Sea.

Ocean drilling ship chosen

NASA Astrophysics Data System (ADS)

Richman, Barbara T.

The Sedco/BP 471, owned jointly by Sedco, Inc., of Dallas, Tex., and British Petroleum, has been selected as the drill ship for the Ocean Drilling Program (ODP). The contract, with a specified initial term of 4 years with 10 1-year options after that, is expected to be signed by mid March by Texas A&M University, the ODP science operator, and Sedco, Inc. Texas A&M will develop the design for scientific and laboratory spaces aboard the Sedco/BP 471 and will oversee the ship conversion. Testing and shakedown of the ship is scheduled for the coming autumn; the first scientific cruise is scheduled for next January.One year ago, the commercial drilling market sagged, opening up the option for leasing a commercial drill ship (Eos, February 22, 1983, p. 73). Previously, the ship of choice had been the Glomar Explorer; rehabilitating the former CIA salvage ship would have been extremely expensive, however.

Offset-vertical seismic profiling for marine gas hydrate exploration: Is it a suitable technique? First results from ODP Leg 164

USGS Publications Warehouse

Pecher, I.A.; Holbrook, W.S.; Stephen, R.A.; Hoskins, H.; Lizarralde, D.; Hutchinson, D.R.; Wood, W.T.

1997-01-01

Walkaway vertical seismic profiles were acquired during Ocean Drilling Project (ODP) Leg 164 at the Blake Ridge to investigate seismic properties of hydrate-bearing sediments and the zone of free gas beneath them. An evaluation of compressional (P-) wave arrivals Site 994 indicates P-wave anisotrophy in the sediment column. We identified several shear (S-) wave arrivals in the horizontal components of the geophone array in the borehole and in data recorded with an ocean bottom seismometer deployed at the seafloor. S-waves were converted from P-waves at several depth levels in the sediment column. One of the most prominent conversion points appears to be the bottom simulating reflector (BSR). It is likely that other conversion points are located in the zone of low P-wave reflectivity above the BSR. Modeling suggests that a change of the shear modulus is sufficient to cause significant shear conversion without a significant normal-incidence P-wave reflection.

The instructional impact of the American Medical Association's Older Drivers Project online curriculum.

PubMed

Meuser, Thomas M; Carr, David B; Berg-Weger, Marla; Irmiter, Cheryl; Peters, Karen E; Schwartzberg, Joanne G

2014-01-01

The Older Drivers Project (ODP) of the American Medical Association has provided evidence-based training for clinicians since 2003. More than 10,000 physicians and other professionals have been trained via an authoritative manual, the Physician's Guide to Assessing & Counseling Older Drivers, and an associated continuing medical education five-module curriculum offered formally by multidisciplinary teams from 12 U.S. States from 2003 to 2008. An hour-long, online version was piloted with medical residents and physicians (N = 259) from six academic and physician office sites from 2010 to 2011. Pre/postsurveys were completed. Most rated the curriculum of high quality and relevant to their practice. A majority (88%) reported learning a new technique or tool, and 89% stated an intention to incorporate new learning into their daily clinical practice. More than one half (62%) reported increased confidence in addressing driving. This transition from in-person to online instruction will allow the ODP to reach many more clinicians, at all levels of training, in the years to come.

Ocean Drilling Program: Drilling Services

Science.gov Websites

Drilling operations team Material services team Development engineering team ODP/TAMU Science Operator Home Services department consists of three team-oriented project groups, which also work to improve the existing team. A member of this team sails with each cruise to provide expertise for the shipboard scientific

Tectonic analysis and paleo-stress determination of the upper lava section at ODP/IODP site 1256 (East Pacific Ocean)

NASA Astrophysics Data System (ADS)

Fontana, Emanuele

2015-09-01

Research on the deep sea is of great importance for a better understanding of the mechanism of magma emplacement and the tectonic evolution of oceanic crust. However, details of the internal structure in the upper levels of the oceanic crust are much less complete than that of the more fully studied sub-aerial areas. For the first time, this study proposes a dynamic analysis using the inversion method on core data derived from the drilled basement of the present-day intact oceanic crust at ODP/IODP Site 1256 in the Cocos plate. The research is based on an innovative core reorientation process and combines different stress hypothesis approaches for the analysis of heterogeneous failure-slip data via exploitation of two distinct techniques. From the analysis of the failure-slip data, both techniques produce 5 distinct subsystem datasets. All calculated subsystems are mechanically and geometrically admissible. Interpretation of the results allows the researchers to note a complex local and regional tectonic evolution deriving from the interplay of (1) the ridge push and rotation of both the East Pacific Rise and the Cocos-Nazca Spreading Center, (2) the effect of the slab pull of the Middle America Trench, (3) the influence of lava emplacement mechanisms, and (4) intra-plate deformation.

Transient formation fluid pressures and temperatures in the Costa Rica forearc prism and subducting oceanic basement: CORK monitoring at ODP Sites 1253 and 1255

NASA Astrophysics Data System (ADS)

Davis, Earl E.; Villinger, Heinrich W.

2006-05-01

Seafloor and formation-fluid pressure data from two Ocean Drilling Program (ODP) borehole hydrologic observatories installed at the toe of the subduction-zone prism off Costa Rica provide new information about the average and transient state of this non-accretionary prism. Data collected to date span a 16-month period from the time of installation during ODP Leg 205 in late 2002 to the most recent submersible site visit in March 2004. Pressure monitoring is part of a larger coordinated effort involving temperature monitoring and continuous fluid sampling within the formation and at the seafloor. The holes are positioned 800 m apart and monitoring points include two in igneous basement just seaward of the prism toe, one in the decollement that separates the underthrust sediments of the incoming Cocos plate from the Costa Rica prism, and one in the overthrust-prism sediments. Response of formation-fluid pressure to oceanographic loading at the seafloor constrains the framework compressibility of basement (ca . 1.1-1.3 × 10 - 10 Pa - 1) and the prism and decollement sediments (ca . 4-7 × 10 - 9 Pa - 1). Values are equivalent to ones determined elsewhere in similar sections. Once effects of seafloor loading are removed, pressures at both basement levels are seen to be steady, nearly identical, and less than but very close to hydrostatic (- 6 kPa). This state probably reflects the local hydrothermal regime of the oceanic crust, not the hydrologic regime of the consolidating subduction complex, and is consistent with basement being highly permeable and hydrologically well connected to distant igneous outcrops where free exchange of water between the crust and the ocean can occur. To what depth in the subduction zone high basement permeability persists is not known, but until permeability is reduced by alteration or mechanical fracture closure, basement must serve to provide a drainage path for water expelled from the consolidating underthrust sedimentary section. The decollement and overlying prism are observed to be superhydrostatic, although not highly so during this phase of observation. Pressures (expressed as the pore pressure ratio) range from λ* ≈ 0.25 at the decollement early in the monitoring period to ≈ 0.1 in the overlying prism at the end of the monitoring period. The cause of the initially elevated pressures is not known. If generated by contractional strain, elevated pressures appear not to be maintained for long periods of time at these lithologic/structural levels. The cause of the decline in pressure is also not known; it may be the consequence of strain relaxation or hydrologic drainage. No observations were made in the underthrust sediments, where greater hydrologic isolation may allow higher average pressures and transient pressures of greater amplitude and persistence. Two minor transients were observed at the decollement- and prism-monitoring levels that correlate with deformational events that occurred during a GPS monitoring experiment on the Nicoya Peninsula. One of these is inferred by Protti et al. [M. Protti, T. Gonzalez, T. Kato, T. Iinuma, S. Miyazaki, K. Obana, Y. Kaneda, P. LaFemina, T. Dixon, S. Schwartz, A creep event on the shallow interface of the Nicoya Peninsula, Costa Rica seismogenic zone, EOS, Trans. Am. Geophys. Union, Fall Meeting Program with Abstracts, 85 (2004) F1378; M. Protti, P. LaFemina, V. Gonzalez, T.H. Dixon, S.Y. Schwartz, T. Kato, T. Iinuma, S. Miyazaki, K. Obana, Y. Kaneda, A possible slow slip event within the seismogenic zone, Nicoya peninsula, Costa Rica, Geophys. Res. Lett. (submitted for publication)] to have propagated some 60 km to the northeast across the peninsula over the course of 2-3 weeks. The pressure transients at the ODP drill sites, located roughly 60 km offshore, began on May 24 and October 12, 2003, also 2-3 weeks after the initiation of the GPS-recorded Nicoya strain events at the coast. Propagation of dislocations updip (offshore) as well as downdip along the subduction thrust may be the cause of these transients.

Seasonal sea ice cover during the warm Pliocene: Evidence from the Iceland Sea (ODP Site 907)

NASA Astrophysics Data System (ADS)

Clotten, Caroline; Stein, Ruediger; Fahl, Kirsten; De Schepper, Stijn

2018-01-01

Sea ice is a critical component in the Arctic and global climate system, yet little is known about its extent and variability during past warm intervals, such as the Pliocene (5.33-2.58 Ma). Here, we present the first multi-proxy (IP25, sterols, alkenones, palynology) sea ice reconstructions for the Late Pliocene Iceland Sea (ODP Site 907). Our interpretation of a seasonal sea ice cover with occasional ice-free intervals between 3.50-3.00 Ma is supported by reconstructed alkenone-based summer sea surface temperatures. As evidenced from brassicasterol and dinosterol, primary productivity was low between 3.50 and 3.00 Ma and the site experienced generally oligotrophic conditions. The East Greenland Current (and East Icelandic Current) may have transported sea ice into the Iceland Sea and/or brought cooler and fresher waters favoring local sea ice formation. Between 3.00 and 2.40 Ma, the Iceland Sea is mainly sea ice-free, but seasonal sea ice occurred between 2.81 and 2.74 Ma. Sea ice extending into the Iceland Sea at this time may have acted as a positive feedback for the build-up of the Greenland Ice Sheet (GIS), which underwent a major expansion ∼2.75 Ma. Thereafter, most likely a stable sea ice edge developed close to Greenland, possibly changing together with the expansion and retreat of the GIS and affecting the productivity in the Iceland Sea.

Development of Overpressures at Nankai Accretionary Prism, Ocean Drilling Program Sites 1173 and 1174

NASA Astrophysics Data System (ADS)

Gamage, K.; Screaton, E.

2003-12-01

In this study, we used a one-dimensional model of sedimentation, initial prism loading, and fluid flow to examine the development of overpressures at the toe of the Nankai accretionary complex. A permeability-porosity relationship was established for hemipelagic sediments from laboratory measured permeabilities as an input to the model. Vertical permeabilities were measured for 10 core samples from the Ocean Drilling Program (ODP) Leg 190, Sites 1173 and 1174, from the upper and lower Shikoku Basin facies. Both sites were drilled along the Muroto Transect through the dècollement zone or its equivalent. Site 1173 is located 11 km seaward of the deformation front and it represents the undeformed incoming sediments, where as Site 1174 represents sediments within the proto-thrust zone. Although turbidite-rich sediments dominate the Nankai accretionary prism, the dècollement and underthrust sediments are primarily composed of hemipelagic muds. Using the permeability-porosity relationship, our modeling results indicate excess pore pressures that are greater than 30% of lithostatic pressure at the toe of the prism at a convergence rate of 4cm/yr. These values are slightly lower than previously inferred excess pore pressures estimated from porosity data. Additional runs were conducted to simulate a 10-m thick low permeability barrier at the dècollement where vertical fluid flow is restricted. The low permeability barrier required a permeability less than 1 x 10-19 m2 to generate excess pore pressures greater than 50% of lithostatic pressure. Modeling was further extended to test the significance of variable prism loading rates due to uncertainties in the convergence rate and affects of lateral stress above the dècollement.

Ocean Drilling Program investigates hydrate ridge

NASA Astrophysics Data System (ADS)

Showstack, Randy

There are several ways to get onboard the JOIDES Resolution, a 143-meter long converted oil tanker that is a floating laboratory, and the pride of the Ocean Drilling Program (ODP). You can meet up with it at a port of call, or set down on its helicopter pad. Or you can hitch a ride by overnight supply boat, and then get lifted by crane to the Resolution by clinging to the outside of a rope transfer basket as this reporter did.

Pliocene-Pleistocene changes in Arctic sea-ice cover: New biomarker records from Fram Strait/Yermak Plateau (ODP Sites 911 and 912)

NASA Astrophysics Data System (ADS)

Stein, Ruediger; Fahl, Kirsten

2013-04-01

Recently, a novel and promising biomarker proxy for reconstruction of Arctic sea-ice conditions was developed and is based on the determination of a highly branched isoprenoid with 25 carbons (IP25; Belt et al., 2007). Following this pioneer IP25 study by Belt and colleagues, several IP25 studies of marine surface sediments and sediment cores as well as sediment trap samples from northpolar areas were carried out successfully and allowed detailed reconstruction of modern and late Quaternary sea ice variability in these regions (e.g., Massé et al., 2008; Müller et al., 2009, 2011; Vare et al., 2009; Belt et al., 2010; Fahl and Stein, 2012; for review see Stein et al., 2012). Here, we present new (low-resolution) biomarker records from Ocean Drilling Program (ODP) Sites 911 and 912, representing the Pliocene-Pleistocene time interval (including the interval of major intensification of Northern Hemisphere Glaciation near 2.7 Ma). These data indicate that sea ice of variable extent was present in the Fram Strait/southern Yermak Plateau area during most of the time period under investigation. In general, an increase in sea-ice cover seems to correlate with phases of extended late Pliocene-Pleistocene continental ice-sheets. At ODP Site 912, a significant increase in sea-ice extension occurred near 1.2 Ma (Stein and Fahl, 2012). Furthermore, our data support the idea that a combination of IP25 and open water, phytoplankton biomarker data ("PIP25 index"; Müller et al., 2011) may give more reliable and quantitative estimates of past sea-ice cover (at least for the study area). This study reveals that the novel IP25/PIP25 biomarker approach has potential for semi-quantitative paleo-sea ice studies covering the entire Quaternary and motivate to carry out further detailed high-resolution research on ODP/IODP material using this proxy. References Belt, S.T., Massé, G., Rowland, S.J., Poulin, M., Michel, C., LeBlanc, B., 2007. A novel chemical fossil of palaeo sea ice: IP25. Organic Geochemistry 38, 16-27. Belt, S.T., Vare, L.L., Massé, G., Manners, H.R., Price, J.C., MacLachlan, S.E., Andrews, J.T., Schmidt, S., 2010. Striking similarities in temporal changes to spring sea ice occurrence across the central Canadian Arctic Archipelago over the last 7000 years. Quaternary Science Reviews 29, 3489-3504. Fahl, K. and Stein, R., 2012. Modern seasonal variability and deglacial/Holocene change of central Arctic Ocean sea-ice cover: New insights from biomarker proxy records. Earth Planetary Science Letters 351-352C, 123-133, doi:10.1016/j.epsl.2012.07.009. Massé, G., Rowland, S.J., Sicre, M.-A., Jacob, J., Jansen, E., Belt, S.T., 2008. Abrupt climate changes for Iceland during the last millennium: Evidence from high resolution sea ice reconstructions. Earth Planetary Science Letters 269, 565-569. Müller, J., Massé, G., Stein, R., Belt, S.T., 2009. Variability of sea-ice conditions in the Fram Strait over the past 30,000 years. Nature Geoscience 2, 772-776. Müller, J., Wagner, A., Fahl, K., Stein, R., Prange, M., Lohmann, G., 2011. Towards quantitative sea ice reconstructions in the northern North Atlantic: A combined biomarker and numerical modelling approach. Earth Planetary Science Letters 306, 137-148. Stein, R. and Fahl, K., 2012. Biomarker proxy IP25 shows potential for studying entire Quaternary Arctic sea-ice history. Organic Geochemistry; doi: 10.1016/j.orggeochem.2012.11.005. Stein, R., Fahl, K., and Müller, J., 2012. Proxy reconstruction of Arctic Ocean sea ice history: "From IRD to IP25". Polarforschung 82, 37-71. Vare, L.L., Massé, G., Gregory, T.R., Smart, C.W., Belt, S.T., 2009. Sea ice variations in the central Canadian Arctic Archipelago during the Holocene. Quaternary Science Reviews 28, 1354-1366.

Ontorat: automatic generation of new ontology terms, annotations, and axioms based on ontology design patterns.

PubMed

Xiang, Zuoshuang; Zheng, Jie; Lin, Yu; He, Yongqun

2015-01-01

It is time-consuming to build an ontology with many terms and axioms. Thus it is desired to automate the process of ontology development. Ontology Design Patterns (ODPs) provide a reusable solution to solve a recurrent modeling problem in the context of ontology engineering. Because ontology terms often follow specific ODPs, the Ontology for Biomedical Investigations (OBI) developers proposed a Quick Term Templates (QTTs) process targeted at generating new ontology classes following the same pattern, using term templates in a spreadsheet format. Inspired by the ODPs and QTTs, the Ontorat web application is developed to automatically generate new ontology terms, annotations of terms, and logical axioms based on a specific ODP(s). The inputs of an Ontorat execution include axiom expression settings, an input data file, ID generation settings, and a target ontology (optional). The axiom expression settings can be saved as a predesigned Ontorat setting format text file for reuse. The input data file is generated based on a template file created by a specific ODP (text or Excel format). Ontorat is an efficient tool for ontology expansion. Different use cases are described. For example, Ontorat was applied to automatically generate over 1,000 Japan RIKEN cell line cell terms with both logical axioms and rich annotation axioms in the Cell Line Ontology (CLO). Approximately 800 licensed animal vaccines were represented and annotated in the Vaccine Ontology (VO) by Ontorat. The OBI team used Ontorat to add assay and device terms required by ENCODE project. Ontorat was also used to add missing annotations to all existing Biobank specific terms in the Biobank Ontology. A collection of ODPs and templates with examples are provided on the Ontorat website and can be reused to facilitate ontology development. With ever increasing ontology development and applications, Ontorat provides a timely platform for generating and annotating a large number of ontology terms by following design patterns. http://ontorat.hegroup.org/.

Lipid-enhancement of activated sludges obtained from conventional activated sludge and oxidation ditch processes.

PubMed

Revellame, Emmanuel D; Hernandez, Rafael; French, W Todd; Holmes, William E; Forks, Allison; Callahan, Robert

2013-11-01

Lipid-enhancement of activated sludges was conducted to increase the amount of saponifiable lipids in the sludges. The sludges were obtained from a conventional activated sludge (CAS) and an oxidation ditch process (ODP). Results showed 59-222% and 150-250% increase in saponifiable lipid content of the sludges from CAS and ODP, respectively. The fatty acid methyl ester (FAMEs) obtained from triacylglycerides was 57-67% (of total FAMEs) for enhanced CAS and 55-73% for enhanced ODP, a very significant improvement from 6% to 10% (CAS) and 4% to 8% (ODP). Regardless of the source, the enhancement resulted in sludges with similar fatty acid profile indicating homogenization of the lipids in the sludges. This study provides a potential strategy to utilize existing wastewater treatment facilities as source of significant amount of lipids for biofuel applications. Published by Elsevier Ltd.

Late Paleocene- Early Eocene paleoenvironments in the Southwest Pacific (ODP Leg 189): Revised Stratigraphy of an Antarctic PETM Record.

NASA Astrophysics Data System (ADS)

Bijl, P. K.; Brinkhuis, H.; Sluijs, A.; Reichart, G.; Schouten, S.; Röhl, U.

2007-12-01

The Late Paleocene and Early Eocene (~60 ¡V 50 Ma) were characterized by globally warm climates. Superimposed on this general warmth, several episodes of further warming occurred (so-called hyperthermals), including the Paleocene-Eocene thermal maximum (PETM, ~55 Ma) and Eocene thermal maximum 2 (ETM2, ~53 Ma). While the PETM is by now well documented from Northern Hemisphere, and some equatorial locations, southern high-latitude records are still rare. Here we present high-resolution palynological, XRF, bulk organic stable carbon isotope (Ô13CTOC), and TEX86 palaeothermometry data across Upper Paleocene through Lower Eocene pro-deltaic deposits from the Southwest Pacific Ocean, at ~65¢XS palaeolatitude (ODP Site 1172). Based on a revised integrated biomagnetostratigraphic age model and Ô13CTOC stratigraphy, we identify the southernmost marginal marine PETM ever encountered. Moreover, there is every indication that ETM2 was recovered as well at Site 1172. Despite a high latitude source of the surface waters at this site, the PETM is marked by the characteristic acme of representatives of the (sub) tropical dinoflagellate cyst (dinocyst) Apectodinium, confirming the truly global nature of this PETM event. TEX86 values indicate that surface ocean temperatures rose from ~23¢XC to ~30¢XC during the PETM at Site 1172, hence by a similar magnitude as recorded in other PETM successions globally. Before and after the CIE, mass abundances of low salinity tolerant dinocysts are recorded, taken as indicative of increased runoff. These trends are analogous to those recorded at northern high latitudes, indicating a similar climate response at both polar regions during the PETM. Yet, some distinct differences are apparent, and are discussed.

The Value of Decision Analytical Modeling in Surgical Research: An Example of Laparoscopic Versus Open Distal Pancreatectomy.

PubMed

Tax, Casper; Govaert, Paulien H M; Stommel, Martijn W J; Besselink, Marc G H; Gooszen, Hein G; Rovers, Maroeska M

2017-11-02

To illustrate how decision modeling may identify relevant uncertainty and can preclude or identify areas of future research in surgery. To optimize use of research resources, a tool is needed that assists in identifying relevant uncertainties and the added value of reducing these uncertainties. The clinical pathway for laparoscopic distal pancreatectomy (LDP) versus open (ODP) for nonmalignant lesions was modeled in a decision tree. Cost-effectiveness based on complications, hospital stay, costs, quality of life, and survival was analyzed. The effect of existing uncertainty on the cost-effectiveness was addressed, as well as the expected value of eliminating uncertainties. Based on 29 nonrandomized studies (3.701 patients) the model shows that LDP is more cost-effective compared with ODP. Scenarios in which LDP does not outperform ODP for cost-effectiveness seem unrealistic, e.g., a 30-day mortality rate of 1.79 times higher after LDP as compared with ODP, conversion in 62.2%, surgically repair of incisional hernias in 21% after LDP, or an average 2.3 days longer hospital stay after LDP than after ODP. Taking all uncertainty into account, LDP remained more cost-effective. Minimizing these uncertainties did not change the outcome. The results show how decision analytical modeling can help to identify relevant uncertainty and guide decisions for future research in surgery. Based on the current available evidence, a randomized clinical trial on complications, hospital stay, costs, quality of life, and survival is highly unlikely to change the conclusion that LDP is more cost-effective than ODP.

Investigating Eastern Equatorial Pacific Export Production and Carbonate Dissolution with XRF Core Scanning at ODP Site 846 Over the Last 5 Million Years

NASA Astrophysics Data System (ADS)

Jones, C.; Robinson, R. S.

2015-12-01

Coastal and equatorial upwelling in the Eastern Equatorial Pacific (EEP) are responsible for about 10% of the ocean's total production. The deep, cold, nutrient-rich waters supplied by upwelling originate in high latitudes, linking changes at high latitudes to the tropics. The Pliocene/Pleistocene transition which started around 2.7-3 million years ago (Ma) marked a period of higher variability in biological production and sea surface temperatures dominated by glacial/interglacial cycles. In addition, secular changes in the development of both Walker and Hadley cells appear to have impacted the strength of equatorial upwelling. However, the large positive production excursions, such as those found from 1.6 to 2.2 Ma, remain only moderately well characterized and both changes in high latitude nutrient supply and regional upwelling strength are implicated. ODP Site 846 is located in the heart of the EEP upwelling cold tongue and has ideal characteristics for examining these links and excursions. We present high-resolution (~0.5 ky) X-Ray Fluorescence (XRF) chemical profiles of Ca, Si, Ba, Mn, Fe, Al, and Ti, as well as a total nitrogen (TN%) record for the last 5 million years from ODP Site 846. We use these high resolution profiles in conjunction with other regional data to assess biogeochemical processes in the EEP over the last 5 million years. CaCO3 and SiO2 are the two dominant biogenic components and account for more than 95% of the sediment. BaSO4 and the discrete TN% measurements record total productivity. MnO and Fe2O3 are redox-sensitive species and are particularly suited to tracing dissolution related to excess bottom-water metabolic processes driven by high export production at the high-alkalinity Site 846. Al2O3 and TiO2 are tracers of terrigenous input. A transition between low amplitude and high amplitude carbonate cycles occurs at 2.8 Ma, coinciding with the Pliocene/Pleistocene transition to higher amplitude glacial cycles. Notable excursions from the baseline high carbonate system occur between 3.8 and 4.2 Ma, between 1.6 and 2.2 Ma, at 0.75 Ma, and within the last 0.1 Ma. These excursions are explored, and causes include heavy contributions from productivity-driven dissolution, some extended instances of CCD-driven dissolution and shifts in overlying productivity towards diatoms.

Microstructure of the optic disc pit in open-angle glaucoma.

PubMed

Choi, Yun Jeong; Lee, Eun Ji; Kim, Bo Hyuk; Kim, Tae-Woo

2014-11-01

To investigate the structural and clinical characteristics of the optic disc pit (ODP) in primary open-angle glaucoma (POAG) via enhanced depth imaging (EDI) spectral-domain optical coherence tomography (SD-OCT). Prospective, observational case series. Seventy POAG eyes clinically diagnosed with an ODP via stereo disc photography. Optic discs were scanned using EDI SD-OCT. Serial horizontal and vertical B-scan images covering the optic discs were obtained from each eye. The structural characteristics of the ODP were investigated via 3-dimensional images constructed from the serial B-scans, focusing on the presence of alterations in the contour of the lamina cribrosa (LC) or prelaminar tissue (PLT), in conjunction with associated clinical characteristics. The structural characteristics of the ODP and associated clinical characteristics. In the EDI SD-OCT images, the ODP was viewed as an isolated alteration of the LC (n = 14, 20.0%) or PLT (n = 16, 22.9%) or an alteration of both the LC and PLT (n = 40, 57.1%). Alterations of the LC were located at the mid-periphery near the LC insertion (n = 17) or far periphery adjacent to the LC insertion (n = 37), and the depth of alteration was deep (n = 23), involving nearly full-thickness LC, or shallow (n = 31), with partially visible LC at the base. Fifty-four eyes (77.1%) exhibited parafoveal visual field (VF) defect within 10 degrees of fixation, and in 98.1% of these eyes (53/54) it was spatially associated with the location of ODP. The parafoveal VF defect was more prevalent in eyes with LC alteration than those without (83.3% vs. 56.2%, P = 0.023) and in eyes with deep LC defect than those with shallow defect (95.7% vs. 74.2%, P = 0.036). Disc hemorrhage (32.4% vs. 0.0%, P = 0.008) and peripapillary retinoschisis (18.9 vs. 0.0%, P = 0.055) were more strongly associated with LC alterations located at the far periphery than at the mid-periphery. Enhanced depth imaging SD-OCT facilitated visualization of the varied structure of the ODP, which presented as alteration of the LC or PLT or both. The clinical significance of differing characteristics of ODP microstructure remains to be determined. Copyright © 2014 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Petrographic Analyses of Lonestones from ODP Drill Sites Leg 188 Prydz Bay, Antarctica

NASA Astrophysics Data System (ADS)

Detterman, K.; Warnke, D. A.; Richter, C.

2006-12-01

ODP Leg 188 was drilled in 2000 to sample the first advances of the Antarctic ice sheet and to document further cryospheric development. Continental shelf Site 1166 documented the earliest stages of glaciation during the Eocene-Oligocene and continental slope Site 1167 documented rapid deposition by debris flows during the Pliocene-Pleistocene and a subtle change in onshore erosion areas. Site 1165, located on the continental rise, documented long-term transition from wet-based lower Miocene glaciers to dry-based upper Miocene glaciers, including short-term fluctuations starting in the early Miocene. Source areas for all drill sites are the Lambert Glacier-Amery Ice Shelf drainage area, encompassing the Northern and Southern Prince Charles Mountains, the Gamburtsev Sub-glacial Mountains, and the Grove Mountains. Lonestones occur in most of the cores from all sites of Leg 188 prompting research for potential source areas and transportation modes of the lonestones. One-hundred and seventeen thin sections of lonestones were prepared from Sites 1166, 1167, and 1165 for petrographic analyses. Metamorphic lonestones outnumber igneous and sedimentary lonestones at all three sites. Sedimentary lonestones were not found in the thin sections of Site 1166. Extrusive igneous lonestones were found only at Site 1165 and comprised 5.1 percent of Leg 188's lithology. The anorthite content of igneous and metamorphic lonestones represented at all three sites was albite-oligoclase plagioclase. Albite oligoclase plagioclase has been documented in the Southern Prince Charles Mountains. The results of this study of a selection of lonestones from Site 1167 supports a hypothesis first proposed by the Shipboard Scientific Party in 2001 that as time elapsed, the source area for Site 1167 lonestones shifted slightly from a largely sandstone source to a largely granitic source within the drainage area. One potential source area for the Site 1167 sandstone lonestones is the Permian to Triassic Amery Group in the Beaver Lake area of the Northern Prince Charles Mountains. We hypothesize that more easily eroded portions of the sandstone outcrops were planed off first while ubiquitous gneiss and granite outcrops provided the source material for the younger debris flows at Site 1167 in the Pliocene-Pleistocene. None of all the available lonestones suggest sources other than the drainage area of the Lambert Glacier- Amery Ice Shelf complex.

Effect of Oxadiazolyl 3(2H)-Pyridazinone on the Larval Growth and Digestive Physiology of the Armyworm, Pseudaletia separata

PubMed Central

Huang, Qingchun; Kong, Yuping; Liu, Manhui; Feng, Jun; Liu, Yang

2008-01-01

The effect of oxadiazolyl 3(2H)-pyridazinone (ODP), a new insect growth regulator, on growth of larvae of the armyworm, Pseudaletia separata Walker (Lepidoptera: Noctuidae) was evaluated in comparison to the insecticide, toosendanin, a tetranortriterpenoid extracted from the bark of Melia toosendan that has multiple effects on insects. The digestive physiological properties of these compounds on insects were investigated by feeding them maize leaves dipped in these compounds. The results showed that ODP inhibited the growth of P. separata significantly, causing a slowed development and a prolonged larval period, smaller body size and sluggish behavior, delayed pupation and a reduced eclosion rate of pupae and adults. Moreover, ODP strongly inhibited the activities of weak alkaline trypsine-like enzyme, chymotrypsin-like enzyme and alpha amylase in the midguts of fifth instar P. separata larvae, in vivo, and inhibited the activity of alpha amylase, in vitro. These data suggest that ODP has severe consequences on the larval carbohydrate assimilation and/or nutrient intake and thereby causes inhibition of larval growth. The regulatory action of ODP on larval growth development was similar to that of toosendanin; both could be used to decrease the growth of insect populations. PMID:20337556

Western Pacific Warm Pool expansion event during 2.0-1.5 Ma and its implications to global climate dynamics

NASA Astrophysics Data System (ADS)

Lo, L.; Chuang, C. K.; Wei, K. Y.; Shen, C. C.; Mii, H. S.; Chang, Y. P.

2017-12-01

In this study, we reconstruct surface and upper thermocline seawater temperatures by using planktonic foraminifera Globigerinoides sacculifer and Neogloboquadrina deutertrei in the southern Western Pacific Warm Pool (S-WPWP, ODP Site 1115B, 9o11'S, 151o34'E, water depth 1149 m) during past 2.2-1.1 million years (Ma). Significant S-WPWP surface warming in both glacial and interglacial periods during 1.86-1.55 Ma is accompanied with gradual upper thermocline cooling. S-WPWP sea surface temperature dropped 2.1oC from 1.50-1.21 Ma but upper thermocline temperature further decreased 1.1oC at this time period. WPWP expansion event is also supported by vertical foraminiferal Mg/Ca-derived temperature profile records in the central WPWP (ODP Site 806, Ford et al. 2015). Although foraminiferal Mg/Ca-derived temperature records from Eastern Equatorial Pacific suggests long-term cooling trend (Wara et al. 2005), alkenone undersaturation index (UK'37)-inferred surface temperature records suggest 1oC warming during 2.0-1.5 Ma (Fedorov et al. 2013). We argue that seasonal expansion of WPWP may be attributable to the meridional thermocline gradient increasing (Martinez-Garcia et al. 2010) during 2.0-1.5 Ma. Long-term extent variability of WPWP could have impact on cross-equatorial energy transportation and meridional precipitation belt movements (Lo et al., 2014).

Detrital sources and water mass circulation in the tropical North Atlantic during the Late Cretaceous to Paleogene

NASA Astrophysics Data System (ADS)

Martin, E. E.; Pugh, E.; Kamenov, G. D.; MacLeod, K. G.

2014-12-01

Seawater Nd isotopes from fossil fish teeth in Campanian to Paleogene calcareous claystone on Demerara Rise in the tropical North Atlantic record a change from epsilon Nd values of -17 to -11 during the late Maastrichtian. This shift has been identified in three different Ocean Drilling Program (ODP) sites that span from 600 to 1500 m paleodepths (ODP sites 1259, 1260 and 1261) and has been interpreted as a transition from a warm saline intermediate water mass formed on the South American margin, referred to as Demerara Bottom Water, to a source from the North Atlantic. A study of corresponding detrital Sr, Nd and Pb isotopes was undertaken to confirm the isotopic values derived from fish teeth record water mass compositions rather than diagenesis or boundary exchange. Several leaching procedures designed to remove Fe-Mn oxide coatings and the seawater signature they carry from the detrital fractions were tested. Sr isotopic data indicate a 0.02 M hydroxylamine hydrochloride (HH) leach was ineffective at removing the Fe-Mn oxides whereas a 1.0 M HH leach produced detrital Sr isotopic values that were consistent for all three sites and plotted farther from the seawater value. Detrital isotopic results can be divided into three intervals: 1) 73 - 66 Ma, when DBW is present, 2) 66 - 61 Ma, during the transition to North Atlantic sources, and 3) <61 Ma, when North Atlantic sources appear to dominate. During interval 1, detrital Nd isotopes increase gradually, while Sr and Pb isotopic ratios are relatively constant. Leading into interval 2, detrital Nd isotopes are fairly constant while there is a stepwise increase in Sr and Pb isotopes. Leading into interval 3, there is a large increase in Nd and decrease in Sr isotopes and a slight decrease in Pb isotopes. The subtle differences in the timing of changes in fish teeth and detrital Nd isotopes suggest the seawater signal is responding to changes in water mass rather than changes in sediment composition (boundary exchange). The timing of the changes in detrital inputs indicates changes in provenance may correlate with the rearrangement of the currents transporting sediment to the region associated with the transition from a water mass sourced from the tropics to a more northern source.

Deep-sea ostracods from the South Atlantic sector of the Southern ocean during the Last 370,000 years

USGS Publications Warehouse

Yasuhara, Moriaki; Cronin, T. M.; Hunt, G.; Hodell, D.A.

2009-01-01

We report changes of deep-sea ostracod fauna during the last 370,000 yr from the Ocean Drilling Program (ODP) Hole 704A in the South Atlantic sector of the Southern Ocean. The results show that faunal changes are coincident with glacial/interglacial-scale deep-water circulation changes, even though our dataset is relatively small and the waters are barren of ostracods until mid-MIS (Marine Isotope Stage) 5. Krithe and Poseidonamicus were dominant during the Holocene interglacial period and the latter part of MIS 5, when this site was under the influence of North Atlantic Deep Water (NADW). Conversely, Henryhowella and Legitimocythere were dominant during glacial periods, when this site was in the path of Circumpolar Deep Water (CPDW). Three new species (Aversovalva brandaoae, Poseidonamicus hisayoae, and Krithe mazziniae) are described herein. This is the first report of Quaternary glacial/interglacial scale deep-sea ostracod faunal changes in the Southern and South Atlantic Oceans, a key region for understanding Quaternary climate and deep-water circulation, although the paucity of Quaternary ostracods in this region necessitates further research. ?? 2009 The Paleontological Society.

40 CFR Appendix B to Subpart A of... - Class II Controlled Substances a

Code of Federal Regulations, 2012 CFR

2012-07-01

... Montreal Protocol, “Where a range of ODPs is indicated, the highest value in that range shall be used for the purposes of the Protocol. The ODPs listed as a single value have been determined from calculations...

40 CFR Appendix B to Subpart A of... - Class II Controlled Substances a

Code of Federal Regulations, 2013 CFR

2013-07-01

... Montreal Protocol, “Where a range of ODPs is indicated, the highest value in that range shall be used for the purposes of the Protocol. The ODPs listed as a single value have been determined from calculations...

40 CFR Appendix B to Subpart A of... - Class II Controlled Substances a

Code of Federal Regulations, 2011 CFR

2011-07-01

... Montreal Protocol, “Where a range of ODPs is indicated, the highest value in that range shall be used for the purposes of the Protocol. The ODPs listed as a single value have been determined from calculations...

Late Pliocene Depositional History and Paleoclimate Reconstructions of the Southwest Pacific

NASA Astrophysics Data System (ADS)

Royce, B.; Patterson, M. O.; Pietras, J.

2017-12-01

Drift deposits off the eastern margin of New Zealand are important archives for the paleoclimate and paleoceanographic history of the southwest Pacific. Ocean Drilling Program (ODP) Site 1123 is located on the North Chatham rise drift just North of the westerly wind driven Subtropical Front (STF) and provides a record of near continuous sediment deposition since the Miocene along the southwest Pacific deep western boundary current (DWBC). While the Miocene and Late Pleistocene portion of this record have been well studied, the Late Pliocene record is less well developed. Southern Ocean geological records demonstrate that Late Pliocene cooling is the transient time bracketing the warmer than present Early Pliocene and bipolar glaciation at 2.7 Ma. A newly developed, robust, and astronomically tuned long-term record of benthic δ13C from ODP Site 1123 spanning the Early to Late Pliocene implies a reduction in Southern Ocean ventilation and lowering of preformed values from waters sourced along the Antarctic margin during the Late Pliocene. Thus, Late Pliocene Southern Hemisphere cooling and sea ice expansion may have drastically reduced outgassing and increased the burial of heat into the deep ocean. South Atlantic records off the west coast of Africa demonstrate an increase in the flux of iron to the open ocean during this time potentially enhancing surface ocean productivity and providing an additional cooling mechanism. Currently, atmospheric transport of dust to the Southern Ocean is dominated by persistent mid-latitude circumpolar westerly winds; this is particularly relevant for dust sourced from New Zealand. The Late Pliocene to Early Pleistocene uplift of the North Island axial ranges and South Island southern alps potentially provided a greater amount of not only sediment to the deep ocean, but also wind blow dust to the Pacific sector of the Southern Ocean. We will present a detailed high-resolution sedimentological study on the development of the Chatham Rise drift during the Late Pliocene in order to understand both the terrigenous flux rate of sediment into the southwest Pacific and changes in surface ocean productivity. Time series analysis on proxy data demonstrates a close coupling between orbital driven perturbations in climate and the depositional history of the Chatham Rise drift.

The Eocene-Oligocene transition at ODP Site 1263, Atlantic Ocean: decreases in nannoplankton size and abundance and correlation with benthic foraminiferal assemblages

NASA Astrophysics Data System (ADS)

Bordiga, M.; Henderiks, J.; Tori, F.; Monechi, S.; Fenero, R.; Thomas, E.

2015-05-01

The biotic response of calcareous nannoplankton to environmental and climatic changes during the Eocene-Oligocene transition (~34.8-32.7 Ma) was investigated at high resolution at Ocean Drilling Program (ODP) Site 1263 (Walvis Ridge, South East Atlantic Ocean), and compared with a lower resolution benthic foraminiferal record. During this time interval, the global climate which had been warm during the Eocene, under high levels of atmospheric CO2 (pCO2), transitioned into the cooler climate of the Oligocene, with overall lower pCO2. At Site 1263, the absolute nannofossil abundance (coccoliths per gram of sediment; N g-1) and the mean coccolith size decreased distinctly across the E-O boundary (EOB; 33.89 Ma), mainly due to a sharp decline in abundance of large-sized Reticulofenestra and Dictyococcites, within ~53 kyr. Since carbonate dissolution did not vary much across the EOB, the decrease in abundance and size of nannofossils may highlight an overall decrease in their export production, which could have led to an increased ratio of organic to inorganic carbon (calcite) burial, as well as variations in the food availability for benthic foraminifers. The benthic foraminiferal assemblage data show the global decline in abundance of rectilinear species with complex apertures in the latest Eocene (~34.5 Ma), potentially reflecting changes in the food source, thus phytoplankton, followed by transient increased abundance of species indicative of seasonal delivery of food to the sea floor (Epistominella spp.; ~34.04-33.54 Ma), with a short peak in overall food delivery at the EOB (buliminid taxa; ~33.9 Ma). After Oi-1 (starting at ~33.4 Ma), a high abundance of Nuttallides umbonifera indicates the presence of more corrosive bottom waters, possibly combined with less food arriving at the sea floor. The most important signals in the planktonic and benthic communities, i.e. the marked decrease of large reticulofenestrids, extinctions of planktonic foraminifer species and more pronounced seasonal influx of organic matter, preceded the major expansion of the Antarctic ice sheet (Oi-1) by ~440 kyr. During Oi-1, our data show no major change in nannofossil abundance or assemblage composition occurred at Site 1263, although benthic foraminifera indicate more corrosive bottom waters following this event. Marine plankton thus showed high sensitivity to fast-changing conditions, possibly enhanced but pulsed nutrient supply, during the early onset of latest Eocene-earliest Oligocene climate change, or to a threshold in these changes (e.g. pCO2 decline, high-latitude cooling and ocean circulation).

Cerium Anomalies in Fossil Fish Teeth Reveal Changes in Bottom Water Oxygenation

NASA Astrophysics Data System (ADS)

Chun, C. O.; Scher, H. D.; Delaney, M. L.

2007-12-01

Shale-normalized rare earths and yttrium (REY) concentrations of fossil fish teeth in deep sea sediments display prominent negative cerium (Ce) anomalies and positive yttrium (Y) anomalies. These features are ultimately inherited from seawater and strongly indicate that fossil fish teeth preserve a seawater REY signature. In seawater, Ce+3 is oxidized to Ce+4, and Ce becomes depleted relative to the other REY's as it partitions into other phases (e.g., ferromanganese oxyhydroxides). The magnitude of Ce depletion in a water mass is thus related to its oxygen content. We hypothesize that changes in the oxygenation of bottom waters may be revealed by examining downcore variability in the magnitude of the Ce anomaly of fossil fish teeth. To test this hypothesis, REY concentrations were measured on samples of cleaned fossil fish teeth recovered from the late Paleogene to early Eocene sections of Ocean Drilling Program (ODP) Sites 1262 and 1263 (lower and upper Walvis Ridge, ODP Leg 208, South Atlantic Ocean). These sites are vertically offset (early Eocene paleodepths were 3700 and 1700 meters, respectively) and have been extensively studied to characterize the oceanic response to the Paleocene/Eocene Thermal Maximum (PETM). Manganese enrichment factors (Mn EF) determined from total digestions of samples from these sites reveal abrupt changes in the oxygenation of bottom waters across the PETM interval. Mn EF's decrease to crustal values (~1) during the PETM, which reflects the reduction of Mn oxides as bottom water oxygen levels were depleted. Mn EF's begin to increase to 6-8 during the 'recovery phase' following the PETM. The Ce anomaly for these samples, Ce/Ce*, was calculated according to the geometric approach reported by Lawrence et al. (2006, Aquatic Geochemistry 12, 39-72), where Ce* represents an interpolation of the expected shale-normalized Ce concentration from near neighbors. In this notation, when Ce/Ce* = 1 no Ce anomaly is present. At upper Walvis Ridge downcore Ce anomalies show a distinct excursion from pre-PETM values between 0.7-0.8 to values ~1.0 during the PETM event. The values return to pre-excursion levels during the recovery phase following the PETM. The results of this study closely follow the evolution of Mn EF's at Walvis Ridge sites. The smallest Ce anomalies (i.e., Ce/Ce* = 1) coincide with Mn EF's of 1, which provide independent evidence for low oxygen levels in the bottom waters bathing these locations. These results confirm the hypothesis that Ce anomalies in fossil fish teeth can be used to assess changes in the oxygenation of bottom waters.

Microscopic character of marine sediment containing disseminated gas hydrate. Examples from the Blake Ridge and the Middle America Trench

USGS Publications Warehouse

Lorenson, T.D.

2000-01-01

The presence of disseminated gas hydrate was inferred based on pore fluid geochemistry and downhole logging data, but was rarely observed at Ocean Drilling Program (ODP) Leg 164 (Blake Ridge), and Leg 170 (Middle America Trench, offshore from Costa Rica) drilling sites. Gas hydrate nucleation is likely to occur first in larger voids rather than in constricted pore space, where capillary forces depress the temperature-pressure stability field for gas hydrate formation. Traditional macroscopic descriptions of sediment fail to detect the microscopic character of primary and secondary porosity in sediment hosting disseminated gas hydrate. Light transmission and scanning electron microscopy of sediments within and below the depth of gas hydrate occurrences reveal at least four general types of primary and secondary porosity: (1) microfossils (diatoms, foraminifera, and spicules) void of infilling sediment, but commonly containing small masses of pyrite framboids; (2) infauna burrows filled with unconsolidated sand and or microfossil debris; (3) irregularly shaped pods of nonconsolidated framboidial pyrite; and (4) nonlithified volcanic ash.

Upper Eocene Spherules at ODP Site 1090B

NASA Technical Reports Server (NTRS)

Liu, S.; Kyte, F. T.; Glass, B. P.; Gersonde, R.

2000-01-01

Our two labs independently discovered upper Eocene microtektites and microkrystites at ODP Site 1090, a new South Atlantic locality near the Agulhus Ridge. This is a significant new data point for the strewn fields of these spherules, which were recently extended into the Atlantic sector of the Southern Ocean when they were reported at ODP Site 689 on the Maude Rise. The microtektites have been regarded as related to North American tektites and the microkrystites as belonging to the clinopyroxene-bearing (cpx) spherule strewn field. Initial reports indicate that Site 1090 contains a complete sequence of upper Eocene sediments composed of diatom and nannofossil oozes. The magneto- and bio-stratigraphy indicate that impact-age sediments should occur in core 30X of Hole 1090B. One of us (FTK) took 2 cc samples at 10 cm intervals over 600 cm of core for Ir analyses and the senior author (SL) took 3 cc samples at 20 cm intervals to search for spherules. Both studies proved successful and additional samples were obtained to confirm initial results and better define the Ir anomaly and spherule abundances. Peak Ir concentrations of 0.97 ng/g were found at 1090B-30X-5, 105-106cm and 0.78 ng/g at 115-116 cm. Anomalous Ir concentrations (greater than 0.1 ng/g) extend over about 100 cm of core. Preliminary results indicate that the excess Ir at this site is about 25 ng per sq cm. About 380 microtektites (>63 pm) and 2492 microkrystites (>63 pm) were recovered over a 1.8 m interval with a peak abundance of microtektites (106/gram) and microkrystites (562/gram) at 1090B-30X- 5, 114-115 cm. The largest microtektite is approximately 960 x 1140 micron in size. About 55 % are spherical, and the rest are disc, cylinder, dumbbell, teardrop, or fragments. Most of the microtektites are transparent colorless, but a few are transparent pale brown or green. Preliminary data indicate that the microtektites at Site 1090 have similar major oxide compositions to those at Site 689. About 50% of the cpx spherules are spherical, the rest are fragments. They range from yellowish translucent to dark opaque. Based on stratigraphic data, occurrence of a positive Ir anomaly, and similar appearance and major oxide compositions of the Site 1090 spherules to those at Site 689, we believe that the spherule layer(s) are the same at both sites. However, there are significant differences between these two sites. At Site 689 the peak abundance of the cpx spherules is slightly below that of the microtektites. We can distinguish no such separation at Site 1090, despite a somewhat higher sediment accumulation rates. Peak Ir concentrations are about four times higher at Site 1090, resulting in a similarly higher total flux of Ir for this site compared to Site 689 on the Maude Rise. This is generally consistent with the flux of cpx spherules (greater than 63 pm) which is estimated to be approximately -2100 per sq cm, about twice that of Site 689D (1040 sq cm) and with the cpx-spherule component being a principal carrier of the Ir signal. The number of microtektites per sq cm (greater than 63 micron) is nearly the same at both sites, approximately 300 in 1090B and 280 in 689B. A decrease in the greater than 63 micron size fraction (consisting primarily of diatoms and radiolaria) is coincident with the spherule layer at both sites suggesting that the impact(s) that produced the spherule layer(s) may have had an adverse affect on the marine plankton.

Fish like it Hot? The response of ichthyolith accumulation to changing climates of the Paleogene

NASA Astrophysics Data System (ADS)

Sibert, E. C.; Zill, M. E.; Bryant, R. M.; Graves, L. G.; Norris, R. D.

2014-12-01

It has been hypothesized that the production of fish in the water column is related to the amount of primary production in the surface waters. Most future Earth scenarios suggest that as the climate warms, increased surface ocean stratification will decrease nutrient availability and therefore net primary productivity and fish production. Here we calculate accumulation rates of ichthyoliths (microfossil fish teeth and shark dermal scales) throughout the Paleogene and find that ichthyolith accumulation is inversely related to hypothesized changes in primary productivity, but is positively related to ocean temperature. At DSDP Site 596 in the South Pacific, and ODP Site 1258 from the equatorial Atlantic, accumulation of fish fossils increase 6-10 fold from the relatively cool Paleocene into the warm Early Eocene Climate Optimum. In contrast, cooling and increased biosilica deposition at the Eocene/Oligocene (E/O) Boundary suggests that the marine ecosystem switched to a highly productive diatom-dominated ocean, which should favor short, efficient food chains and increased fish production. However, we find that at both Pacific DSDP Site 596 and Atlantic DSDP Site 522, fish accumulation drops by about 50% across the E/O. Indeed, this relation between ichthyolith accumulation and δ18O-estimated paleotemperature is also seen in the Oligocene, at North Pacific ODP Site 886, where warming in the middle Oligocene is mirrored by an increase in ichthyolith accumulation. It appears that ichthyolith accumulation rate may not be purely an effect of total primary production in the water column but rather, may reflect a fundamental response in fish physiology or ecosystem efficiency to warmer water. It has been documented that respiration is faster and more efficient in warm waters, and this may help generate more efficient food web links that compensate for any decrease in primary productivity caused by global warming. Indeed, it appears that fish seem to thrive as the temperature goes up.

Sediment color and reflectance record from Ocean Drilling Program Hole 625B, Gulf of Mexico (marine isotope stage 5 interval)

USGS Publications Warehouse

Dowsett, Harry J.

1999-01-01

Analysis of climate indicators from the North Atlantic, California Margin, and ice cores from Greenland suggest millennial scale climate variability is a component of earth's climate system during the last interglacial period (marine oxygen isotope stage 5). The USGS is involved in a survey of high resolution marine records covering the last interglacial period (MIS 5) to further document the variability of climate and assess the rate at which climate can change during warm intervals. The Gulf of Mexico (GOM) is an attractive area for analysis of climate variability and rapid change. Changes in the Mississippi River Basin presumably are translated to the GOM via the river and its effect on sediment distribution and type. Likewise, the summer monsoon in the southwestern US is driven by strong southerly winds. These winds may produce upwelling in the GOM which will be recorded in the sedimentary record. Several areas of high accumulation rate have been identified in the GOM. Ocean Drilling Program (ODP) Site 625 appears to meet the criteria of having a well preserved carbonate record and accumulation rate capable of discerning millennial scale changes.

A RESCUE THERAPY FOR PERSISTENT OPTIC DISK PIT MACULOPATHY IN PREVIOUSLY VITRECTOMIZED EYES.

PubMed

Figueroa, Marta S; Nadal, Jeroni; Contreras, Inés

2018-01-01

To report the results of vitrectomy with platelet-rich plasma (PRP) application and gas tamponade as a rescue therapy in previously vitrectomized eyes with optic disk pit (ODP) maculopathy. Three patients with visual loss due to persistent or recurrent ODP maculopathy who had undergone previous vitrectomy were offered application of PRP. Platelet-rich plasma was obtained by centrifugation of a blood sample from each patient. Surgery consisted of vitrectomy and internal limiting membrane peeling if the membrane had not been already removed (in two eyes). After fluid/air exchange, three drops of PRP were applied on the ODP followed by 8% C3F8 tamponade. Immediately after surgery, the patient remained supine for 30 minutes and then kept a face-down position for 2 weeks. Optic disk pit maculopathy improved as soon as two weeks after surgery and resolved in all eyes between six and eight months after PRP application. Patients were followed up for three years, with no recurrences. Visual acuity remained stable in one eye and improved in two eyes. Vitrectomy with PRP application may be useful as a rescue therapy in patients with refractory ODP maculopathy. Platelet-rich plasma may act by promoting the closure of the communication between the vitreous and the intraretinal/subretinal space at the pit. This treatment may avoid potentially harmful maneuvers that have been used to treat ODP maculopathy.

Evolution of cannibalism and female's response to oviposition-deterring pheromone in aphidophagous predators.

PubMed

Martini, Xavier; Haccou, Patsy; Olivieri, Isabelle; Hemptinne, Jean-Louis

2009-09-01

1. Egg cannibalism by larvae is common in Coccinellidae and is known to be advantageous for the cannibals. Furthermore, larvae of aphidophagous ladybirds usually produce an oviposition-deterring pheromone (ODP), which inhibits oviposition by adult females. It has been proposed that the response to ODP has evolved because of the high costs of cannibalism. However, this has never been formally proved. 2. In this paper, we study the theoretical evolution of this system. We first look at the conditions under which cannibalism and the response to ODP can evolve. Subsequently, we examine the occurrence of polymorphism both in the production of larval tracks and in the sensitivity of females to specific pheromones. 3. The models predict that the amount of cannibalism should not depend on prey density and that evolution should lead to a continuous increase in cannibalism, and consequently larvae should always cannibalize eggs when possible. In response to the cost of cannibalism, ODP recognition can evolve, so that females avoid laying eggs in patches of prey already occupied by conspecific larvae. The result is an arms race between larvae and adult females, which favours a diversification of ODP pheromones. Our models show that: (i) females should be able to recognize mixtures of hydrocarbons rather than a single molecule; and (ii) females should be more sensitive to the tracks of their own offspring than those of non-related larvae.

A coordinated increase in export production and denitrification on the Costa Rica margin during the early Pleistocene

NASA Astrophysics Data System (ADS)

Yuan, V.; Bascom, C., Jr.; Robinson, R. S.

2013-12-01

The oceanic carbon, nitrogen, and oxygen cycles are linked through export production, oxygen consumption, and denitrification. Denitrification, the bacterial reduction of nitrate, is an anoxic process that serves as the primary sink for fixed nitrogen in the ocean. The Eastern Tropical Pacific (ETP) houses an oxygen minimum zone (OMZ) where pelagic denitrification proceeds as a result of both large scale circulation and regionally high export of organic matter that fuels oxygen consumption in the subsurface. Here we present a 2.4 million year long record of denitrification and productivity in the ETP using ODP Site 1242. Site 1242 is located ~70 km off the west coast of Costa Rica, beneath the OMZ. Downcore records of bulk sedimentary nitrogen isotope values (δ15N) and opal and organic matter accumulation rates show near synchronous increases in δ15N values and biogenic sediment accumulation at approximately 1.6 My. The concurrent increase in the denitrification and productivity proxies suggests that regional oxygen demand could be driving the increase in denitrification observed at Site 1242. This is in contrast to what is observed elsewhere, where export productivity and denitrification changes do not appear to be coupled locally. Moreover, the timing of this increase is distinct from a previously observed increase in δ15N at California Margin Site 1012 which occurred at ~2.1 Ma (Liu et al., G-cubed, 2008) and is also attributed to enhanced denitrification in the OMZ. These differences suggest that the Site 1242 record reflects a purely local or regional process. Interestingly, the later increase in denitrification at 1.6 Ma observed at Site 1242 does not appear to be restricted to the ETP, but rather shows similar timing to a δ15N shift in a site from the Arabian Sea OMZ (Muzuka et al., Proceedings of the ODP, 1991). The new data presented here will help in the development of a mechanistic understanding of relative roles of local and regional processes over global controls on intermediate water OMZ intensity.

East Mariana Basin tholeiites: Cretaceous intraplate basalts or rift basalts related to the Ontong Java plume?

USGS Publications Warehouse

Castillo, P.R.; Pringle, M.S.; Carlson, R.W.

1994-01-01

Studies of seafloor magnetic anomaly patterns suggest the presence of Jurassic oceanic crust in a large area in the western Pacific that includes the East Mariana, Nauru and Pigafetta Basins. Sampling of the igneous crust in this area by the Deep Sea Drilling Program (DSDP) and the Ocean Drilling Program (ODP) allows direct evaluation of the age and petrogenesis of this crust. ODP Leg 129 drilled a 51 m sequence of basalt pillows and massive flows in the central East Mariana Basin. 40Ar 39Ar ages determined in this study for two Leg 129 basalts average 114.6 ?? 3.2 Ma. This age is in agreement with the Albian-late Aptian paleontologic age of the overlying sediments, but is distinctively younger than the Jurassic age predicted by magnetic anomaly patterns in the basin. Compositionally, the East Mariana Basin basalts are uniformly low-K tholeiites that are depleted in highly incompatible elements compared to moderately incompatible ones, which is typical of mid-ocean ridge basalts (MORB) erupted near hotspots. The Sr, Nd and Pb isotopic compositions of the tholeiites ( 87Sr 86Srinit = 0.70360-0.70374; 143Nd 144Ndinit = 0.512769-0.512790; 206Pb 204Pbmeas = 18.355-18.386) also overlap with some Indian Ocean Ridge MORB, although they are distinct from the isotopic compositions of Jurassic basalts drilled in the Pigafetta Basin, the oldest Pacific MORB. The isotopic compositions of the East Mariana Basin tholeiites are also similar to those of intraplate basalts, and in particular, to the isotopic signature of basalts from the nearby Ontong Java and Manihiki Plateaus. The East Mariana Basin tholeiites also share many petrologic and isotopic characteristics with the oceanic basement drilled in the Nauru Basin at DSDP Site 462. In addition, the new 110.8 ?? 1.0 Ma 40Ar 39Ar age for two flows from the bottom of Site 462 in the Nauru Basin is indistinguishable from the age of the East Mariana Basin flows. Thus, while magnetic anomaly patterns predict that the igneous basement in the Nauru and East Mariana Basins is Jurassic in age, the geochemical and chronological results discussed here suggest that the basement formed during a Cretaceous rifting event within the Jurassic crust. This magmatic and tectonic event was created by the widespread volcanism responsible for the genesis of the large oceanic plateaus of the western Pacific. ?? 1994.

Humans Do It Better: Inside the Open Directory Project.

ERIC Educational Resources Information Center

Sherman, Chris

2000-01-01

Explains the Open Directory Project (ODP), an attempt to catalog the World Wide Web by creating a human-compiled Web directory. Discusses the history of the project; open source models; the use of volunteer editors; quality control; problems and complaints; and use of ODP data by commercial services such as Google. (LRW)

Nucleic acid based quantitative microbial community analysis in different marine and terrestrial sediments

NASA Astrophysics Data System (ADS)

Schippers, A.; Blazejak, A.; Köweker, G.

2009-12-01

Sub-seafloor sediments harbour over half of all prokaryotic cells on Earth. This immense cell number is calculated from numerous microscopic cell counts (AODC) in ODP sediment cores. Since AODC can not differentiate between living or dead cells, the population size of living microorganisms and the abundance of different prokaryotic groups are unknown. Recent molecular nucleic acid and biomarker analyses showed that a high proportion of the cells are alive and that the microbial communities of deep marine sediments harbour members of distinct, uncultured bacterial and archaeal lineages. The main objective of our project is the quantification of living prokaryotes in various sediments. Deep sediment samples from the Pacific and the Atlantic Oceans (ODP Legs 201 and 207, IODP Exp. 307 and 308), sediments from the Indian Ocean (RV Sonne 189-2) and the Black Sea (RV Meteor 51/4) as well as terrestrial Chesapeake Bay Sediments (ICDP) were analyzed using Catalyzed Reporter Deposition - Fluorescence In Situ Hybridisation (CARD - FISH) and quantitative, real-time PCR (Q-PCR), targeting either the 16S rRNA gene or the functional genes dsrA, mcrA and aprA to quantify microorganisms of various phylogenetic or physiological groups (e.g. JS1 cluster and Chloroflexi). At all sediment sites, cell numbers decreased with depth, however, the abundance of particular microbial groups varied at different sites and depths. The results indicate that global estimates of the deep biosphere should be reconsidered.

Late Neogene benthic stable isotope record of ODP Site 999: Implications for Caribbean paleoceanography, organic carbon burial and the Messininian salinity crisis

NASA Astrophysics Data System (ADS)

Bickert, T.; Haug, G.; Tiedemann, R.

2003-04-01

The late Neogene closure of the seaway between the North and South American continents is thought to have caused extensive changes in ocean circulation and Northern Hemisphere climate. The timing and consequences of the emergence of the Isthmus of Panama for the ocean circulation have been addressed in several papers which indicate a marked reorganization of surface and deep ocean circulation starting 4.6 million years ago. However, the biogeographic development of marine faunas and floras on both sides of the Panama Isthmus suggests that the paleoceanographic changes related to the closing of the isthmus started much earlier. Furthermore, the closing history of the Panama Seaway overlaps with the tectonic evolution of other ocean gateways in the late Miocene, especially the closure of the Strait of Gibraltar, which led to a transient isolation of the Mediterranean Sea from the Atlantic Ocean, known as the Messinian Salinity Crisis. We report on epibenthic foraminiferal d18O and d13C and percentage sand records of the carbonate fraction from Caribbean ODP Site 999 (12°44´N, 78° 44´W, water depth 2828 m) spanning the interval from 8.6 to 5.3 Ma. Low epibenthic d13C values and low sand contents indicate a poorly ventilated deep Caribbean throughout the late Miocene. At this time the deep Caribbean was dominated by a nutrient-rich Southern Ocean water mass. A mostly constant d13C gradient between the Caribbean and deep Atlantic records suggests that the fluctuations in d13C reflect rather global changes in d13C of the dissolved inorganic carbon due to varying erosion of organic carbon from terrigenous soils and shelf sediments. The observed 100-ky cyclicity of epibenthic d13C is in well accordance with the variability of the terrigenous input to the equatorial Atlantic as recorded by susceptibility records of the Ceara Rise. However, some gradient changes between 6.8 and 5.6 Ma indicate a poorer ventilation of the deep Atlantic related to a reduced production of NADW. The Messinian Salinity Crisis between 6.0 and 5.3 Ma did not affect the intermediate to deep water gradient between the Caribbean and the Atlantic. Comparison to the Bahama platform record of ODP Site 1006, however, indicate a poorer ventilation of the shallower Northern Caribbean basins synchronous to the isolation of the Mediterranean Sea.

Magnetization of lower oceanic crust and upper mantle

NASA Astrophysics Data System (ADS)

Kikawa, E.

2004-05-01

The location of the magnetized rocks of the oceanic crust that are responsible for sea-floor spreading magnetic anomalies has been a long-standing problem in geophysics. The recognition of these anomalies was a key stone in the development of the theory of plate tectonics. Our present concept of oceanic crustal magnetization is much more complex than the original, uniformly magnetized model of Vine-Matthews-Morley Hypothesis. Magnetic inversion studies indicated that the upper oceanic extrusive layer (Layer 2A of 0.5km thick) was the only magnetic layer and that it was not necessary to postulate any contribution from deeper parts of oceanic crust. Direct measurements of the magnetic properties of the rocks recovered from the sea floor, however, have shown that the magnetization of Layer 2A, together with the observations that this layer could record geomagnetic field reversals within a vertical section, is insufficient to give the required size of observed magnetic anomalies and that some contribution from lower intrusive rocks is necessary. Magnetization of oceanic intrusive rocks were observed to be reasonably high enough to contribute to sea-floor spreading magnetic anomalies, but were considered somewhat equivocal until late 1980Os, in part because studies had been conducted on unoriented dredged and ophiolite samples and on intermittent DSDP/ODP cores. Since ODP Leg 118 that cored and recovered continuous 500m of oceanic intrusive layer at Site 735B, Southwest Indian Ridge with an extremely high recovery of 87 percent, there have been several ODP Legs (legs 147, 153, 176, 179 and 209) that were devoted to drilling gabbroic rocks and peridotites. In terms of the magnetization intensities, all of the results obtained from these ODP Legs were supportive of the model that a significant contribution must come from gabbros and peridotites and the source of the lineated magnetic anomalies must reside in most of the oceanic crust as well as crust-mantle boundary. However, it would be wise to note that similar to upper extrusive layer, geomagnetic field reversals were observed for Leg 153 gabbros and that process of magnetization acquisition of mantle peridotites still remains unclear, though we believe mantle peridotites acquire CRM with the formation of magnetite during the process of serpentinization near the ridge axis.

The circum-Antarctic sedimentary record; a dowsing rod for Antarctic ice in the Eocene

NASA Astrophysics Data System (ADS)

Scher, H.

2012-12-01

Arguments for short-lived Antarctic glacial events during the Eocene (55-34 Ma) are compelling, however the paleoceanographic proxy records upon which these arguments are based (e.g., benthic δ18O, eustatic sea level, deep sea carbonate deposition) are global signals in which the role of Antarctic ice volume variability is ambiguous. That is to say, the proxy response to ice volume may be masked other processes. As a result broad correlations between proxies for ice volume are lacking during suspected Eocene glacial events. I will present a more direct approach for detecting Antarctic ice sheets in the Eocene; utilizing provenance information derived from the radiogenic isotopic composition of the terrigenous component of marine sediments near Antarctica. The method relies on knowledge that marine sediments represent a mixture derived from different basement terrains with different isotopic fingerprints. A key issue when using sedimentary deposits to characterize continental sediment sources is to deconvolve different sources from the mixed signal of the bulk sample. The pioneering work of Roy et al. (2007) and van de Flierdt et al. (2007) represents a major advance in Antarctic provenance studies. It is now known that the isotopic composition of neodymium (Nd) and hafnium (Hf) in modern circum-Antarctic sediments are distributed in a pattern that mimics the basement age of sediment sources around Antarctica. For this study I selected two Ocean Drilling Program (ODP) sites on southern Kerguelen Plateau (ODP Sites 738 and 748) because of their proximity to Prydz Bay, where Precambrian sediment sources contribute to extremely nonradiogenic isotopic signatures in modern sediments in the Prydz Bay region. New detrital Nd isotope records from these sediment cores reveal an Nd isotope excursion at the Bartonian/Priabonian boundary (ca. 37 Ma) that coincides with a 0.5 ‰ increase in benthic foram δ18O values. Detrital sediment ɛNd values are around -12 in intervals where δ18O values are low and decrease to -15.5 when δ18O values are highest. In contrast there is not a significant change in the ɛNd values of fossil fish teeth across the δ18O excursion at ODP Site 738. Low variability in fossil fish tooth ɛNd values precludes a major reorganization of bottom water circulation that may otherwise have transported terrigenous sediment from distal areas. Thus, the results from this study provide very strong evidence for an increase in the amount of fine-grained terrigenous material that was discharged from the Prydz Bay drainage and/or a change in the sediment source. I argue that these data provide evidence for erosion/weathering of Antarctic basement rocks by small ice sheets that formed in the hinterland of the Prydz Bay drainage. The approach that will be presented holds great promise for identifying short-lived glaciations on Antarctica prior to the major development of ice sheets at the Eocene Oligocene boundary. Understanding the timing, frequency, and duration of these events is paramount to evaluating the processes and feedbacks that resulted in the global transition from greenhouse to icehouse. References: Roy, M., et al. (2007), Chemical Geology, 244, 507-519. van de Flierdt T, Goldstein SL, Hemming SR, et al, Earth and Planetary Science Letters, 2007, 259, Pages:432-441.

Late Pliocene/Pleistocene changes in Arctic sea-ice cover: Biomarker and dinoflagellate records from Fram Strait/Yermak Plateau (ODP Sites 911 and 912)

NASA Astrophysics Data System (ADS)

Stein, Ruediger; Fahl, Kirsten; Matthiessen, Jens

2014-05-01

Sea ice is a critical component in the (global) climate system that contributes to changes in the Earth's albedo (heat reduction) and biological processes (primary productivity), as well as deep-water formation, a driving mechanism for global thermohaline circulation. Thus, understanding the processes controlling Arctic sea ice variability is of overall interest and significance. Recently, a novel and promising biomarker proxy for reconstruction of Arctic sea-ice conditions was developed and is based on the determination of a highly-branched isoprenoid with 25 carbons (IP25; Belt et al., 2007; PIP25 when combined with open-water phytoplankton biomarkers; Müller et al., 2011). Here, we present biomarker data from Ocean Drilling Program (ODP) Sites 911 and 912, recovered from the southern Yermak Plateau and representing information of sea-ice variability, changes in primary productivity and terrigenous input during the last about 3.5 Ma. As Sites 911 and 912 are close to the modern sea-ice edge, their sedimentary records seem to be optimal for studying past variability in sea-ice coverage and testing the applicability of IP25 and PIP25 in older sedimentary sequences. In general, our biomarker records correlate quite well with other climate and sea-ice proxies (e.g., dinoflagellates, IRD, etc.). The main results can be summarized as follows: (1) The novel IP25/PIP25 biomarker approach has potential for semi-quantitative paleo-sea ice studies covering at least the last 3.5 Ma, i.e., the time interval including the onset (intensification) of major Northern Hemisphere Glaciation (NHG). (2) These data indicate that sea ice of variable extent was present in the Fram Strait/southern Yermak Plateau area during most of the time period under investigation. (3) Elevated IP25/PIP25 values indicative for an extended spring sea-ice cover, already occurred between 3.6 and 2.9 Ma, i.e., prior to the onset of major NHG. This may suggest that sea-ice and related albedo effects might have been important for general cooling and ice-sheet build-up. (4) Maxima in sea ice occurred near 3.3, 2.7, 2.1, 1.7 and during the last 1.2 Ma whereas between about 2.6 and 2.2 Ma the sea-ice cover was surprisingly reduced. The IP25 maxima are similar to those determined for the late Holocene. (5) Both, dinoflagellate and IP25/PIP25 data indicate that also during the Late Pliocene Warming Event at least occasionally sea ice must have occurred. (6) This low-resolution pilot study motivates to carry out further detailed high-resolution sea-ice biomarker research on ODP/IODP material in order to prove or disprove these preliminary interpretations. References Belt, S.T., Massé, G., Rowland, S.J., Poulin, M., Michel, C., LeBlanc, B., 2007. A novel chemical fossil of palaeo sea ice: IP25. Organic Geochemistry 38, 16-27. Müller, J., Wagner, A., Fahl, K., Stein, R., Prange, M., Lohmann, G., 2011. Towards quantitative sea ice reconstructions in the northern North Atlantic: A combined biomarker and numerical modelling approach. Earth Planetary Science Letters 306, 137-148.

Radiometric Ages From ODP Leg 197 Drilling Along the Emperor Seamount Chain

NASA Astrophysics Data System (ADS)

Duncan, R. A.; Huard, J.

2002-12-01

The Hawaiian-Emperor Seamount chain is the "type" example of an age-progressive, hotspot-generated intraplate volcanic lineament. However, our current knowledge of the age distribution within this province is based on radiometric ages determined several decades ago. Improvements in instrumentation, sample preparation methods and new material obtained by recent drilling warrant a re-examination of the age relations among the older Hawaiian volcanoes. We report new age determinations (40Ar-39Ar incremental heating method) on whole rocks and feldspar separates from Detroit (Sites 1203 and 1204), Nintoku (Site 1205) and Koko (Site 1206) seamounts in the Emperor chain, recovered by drilling during ODP Leg 197. Only normal magnetic polarity was observed at Sites 1203 and 1204, and biostratigraphic data assigned ages of 75-76 Ma (nanofossil zone cc22) to sediments interbedded with lava flows. Plateaus in incremental heating age spectra give a mean age for Site 1203 of 75.3 +/- 1.0 Ma (relative to biotite monitor FCT-3 at 28.04 Ma; all errors are 2s). Site 1204 lavas have produced only discordant data so far (5 samples). These new ages are significantly younger than the 81 Ma age reported by Keller et al. (1995) for Site 884 (reverse polarity lavas) on the northeastern flank of Detroit seamount, and suggest that this complex may include several large volcanoes. All volcanic units at Site 1205 exhibit reverse polarity magnetization and biostratigraphic data place the lowermost sediments close to the Eocene-Paleocene boundary. Six plateau ages from lava flows spanning the 283m cored section give a mean age of 55.6 +/- 0.2 Ma (range: 55.2-56.4 Ma), corresponding to Chron 24r. Drilling at Site 1206 intersected a 278m N-R-N sequence of lava flows. Six plateau ages give a mean age of 49.1 +/- 0.2 Ma (range: 47.9-49.7 Ma), corresponding to the Chron 21n-21r-22n sequence. Deep penetration at the three seamounts and shipboard geochemical data suggest that the main shield-post shield stages of volcano development have been sampled at each location and dated. While the overall trend is decreasing volcano age from N to S along the Emperor Seamounts, there appear to be important departures from the earlier modeled simple linear age progression.

Hole 504B reclaimed for future drilling

NASA Astrophysics Data System (ADS)

Leg 137 Scientific Drilling Party

Hole 504B, perhaps the most important in situ reference section for the structure and composition of the oceanic crust, has been reopened for future drilling and downhole measurements after remedial operations during Leg 137 of the Ocean Drilling Program. By far the deepest penetration into oceanic crust, Hole 504B had been feared lost when a large diamond bit and assorted hardware (“junk”) broke off in the bottom of the hole at the end of ODP Leg 111 in 1986. Since then ODP's drill ship, JOIDES Resolution, has circumnavigated the globe, with no opportunity to redress this situation. But the objective of deep penetration into the oceanic crust and the hole itself are considered so important by marine Earth scientists that remedial measures in Hole 504B were undertaken as soon as the drill ship returned to the eastern Pacific. These measures succeeded better than had been hoped. Hole 504B was reopened after less than a week of cleaning operations, which included grappling for the lost junk with tools to pull it from the hole (called “fishing”) and grinding or milling the junk away.

New Sedimentary Records from Contourite Drifts on the West Antarctic Continental Margin: Reconstruction of Palaeoenvironmental Changes during the Late Quaternary by Combining an Integrated Chronostratigraphic Approach with Multi-Proxy Investigations

NASA Astrophysics Data System (ADS)

Hillenbrand, C. D.; Crowhurst, S.; Channell, J. E. T.; Williams, M.; Hodell, D. A.; Xuan, C.; Allen, C. S.; Ehrmann, W. U.; Graham, A. G. C.; Larter, R. D.

2016-12-01

Giant sediment drifts located on the continental rise west of the Antarctic Peninsula and in the Bellingshausen Sea contain a high-resolution archive of ice sheet history in West Antarctica and of palaeoceanographic changes in the Southern Ocean. However, previous studies on sediment cores recovered from these contourite drifts, including Ocean Drilling Program (ODP) Leg 178, were compromised by lack of reliable high-resolution chronological control. This shortcoming is mainly caused by the very low abundance of calcareous microfossils in the sediments that are required for applying radiocarbon dating and stable oxygen isotope (δ18O) stratigraphy. Moreover, sediments assumed to have been deposited during glacial periods consist almost entirely of terrigenous detritus, i.e. they lack even siliceous microfossils that could be utilised for biostratigraphic purposes. International Ocean Discovery Program (IODP) proposal 732-Full2 aims to obtain continuous, high-resolution records from sites on the West Antarctic sediment drifts and to develop reliable age models for them. The strategy for achieving the second objective is to use a range of chronostratigraphic techniques, including relative geomagnetic palaeointensity (RPI) and δ18O stratigraphy, on sedimentary sequences recovered from the shallowest parts of the drift crests, where the preservation of calcareous microfossils is expected be higher than in deeper water. Here we present preliminary results of multi-proxy investigations on new piston and box cores recovered from the proposed drill sites during site survey investigation cruise JR298 of the RRS James Clark Ross in 2015. Apart from the integrated chronological approach, the new cores augment previous assessments of palaeoenvironmental change on the West Antarctic continental margin during glacial-interglacial cycles of the Late Quaternary.

The hydrogeology of the Costa Rica Rift as constrained by results of ocean drilling program downhole experiments

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

Fisher, A.T.; Becker, K.; Narasimhan, T.

1990-06-01

Pore fluids are passively convecting through young oceanic sediments and crust around Deep Sea Drilling Project (DSDP) site 504 on the southern flank of the Costa Rica Rift, as inferred from a variety of geological, geochemical, and geothermal observations. The presence of a fluid circulation system is supported by new data collected on Ocean Drilling Program (ODP) Leg 111 and a predrilling survey cruise over the heavily sedimented, 5.9 Ma site; during the latter, elongated heat flow anomalies were mapped subparallel to structural strike, with individual measurements of twice the regional mean value, and large lateral and vertical geochemical gradientsmore » were detected in pore waters squeezed from sediment cores. Also, there is a strong correlation between heat flow, bathymetry, sediment thickness, and inferred fluid velocities up through the sediments. On an earlier DSDP leg, an 8-bar underpressure was measured in the upper 200 m of basement beneath thick sediment cover. The widely varied geothermal and hydrogeological observations near site 504 are readily explained by a model that combines (1) basement relief, (2) irregular sediment drape, (3) largely conductive heat transfer through the sediments overlying the crust, and (4) thermal and geochemical homogenization of pore fluids at the sediment/basement interface, which results from (5) topographically induced, passive hydrothermal circulation with large aspect ratio, convection cells. This convection involves mainly the permeable, upper 200-300 m of crust; the deeper crust is not involved. This convection is induced through a combination of buoyancy fluxes, owing to heating from below, and topographic variations on the seafloor and at the basement-sediment interface.« less

Implications of China's Open-Door Policy for Families: A Family Impact Analysis

ERIC Educational Resources Information Center

Quach, Andrew S.; Anderson, Elaine A.

2008-01-01

China's open-door policy (ODP) was created in 1978 as a response to the severe economic depression affecting the country after the Cultural Revolution. The policy was designed to restore China's financial status and lift the nation out of destitution. By all accounts, the ODP has been successful in improving the country's monetary condition.…

Object motion analysis study

NASA Technical Reports Server (NTRS)

1974-01-01

The use of optical data processing (ODP) techniques for motion analysis in two-dimensional imagery was studied. The basic feasibility of this approach was demonstrated, but inconsistent performance of the photoplastic used for recording spatial filters prevented totally automatic operation. Promising solutions to the problems encountered are discussed, and it is concluded that ODP techniques could be quite useful for motion analysis.

Marine geochemical cycles of the alkali elements and boron: the role of sediments

NASA Astrophysics Data System (ADS)

James, Rachael H.; Palmer, Martin R.

2000-09-01

We have analysed the concentrations of Li, K, Rb, Cs, and B, and the isotopic ratios of Li and B of a suite of pore fluids recovered from ODP Sites 1037 (Leg 169; Escanaba Trough) and 1034 (Leg 169S; Saanich Inlet). In addition, we have analysed dissolved K, Rb, and Cs concentrations for estuarine mixing of the Ganges-Brahmaputra river system. Together, these data sets have been used to assess the role of sediments in the marine geochemical cycles of the alkali elements and boron. Uptake onto clay minerals during estuarine mixing removes 20-30% of the riverine input of dissolved Cs and Rb to the oceans. Prior to this study, the only other recognised sink of Rb and Cs was uptake during low-temperature alteration of the oceanic crust. Even with this additional sink there is an excess of inputs over outputs in their modern oceanic mass balance. Pore fluid data show that Li and Rb are transferred into marine sediments during early diagenesis. However, modeling of the Li isotope systematics of the pore fluids from Site 1037 shows that seawater Li taken up during marine sedimentation can be readily returned to solution in the presence of less hydrated cations, such as NH 4+. This process also appears to result in high concentrations of pore fluid Cs (relative to local seawater) due to expulsion of adsorbed Cs from cation exchange sites. Flux calculations based on pore fluid data for a series of ODP sites indicate that early diagenesis of clay sediments removes around 8% of the modern riverine input of dissolved Li. Although NH 4+-rich fluids do result in a flux of Cs to the oceans, on the global scale this input only augments the modern riverine Cs flux by ˜3%. Nevertheless, this may have implications for the fate of radioactive Cs in the natural environment and waste repositories.

Sulfur isotope fractionation derived from reaction-transport modeling in the Eastern Equatorial Pacific (ODP Leg 201, Site 1226)

NASA Astrophysics Data System (ADS)

Tsang, M. Y.; Wortmann, U.

2016-12-01

Recent theoretical models suggest that low cell-specific sulfate reduction rates (csSRR) in marine sediments should result in high S-isotope fractionation factors (1). Existing studies on marginal sediments show actual fractionation factors indeed approach the theoretical equilibrium fractionation of 70‰ (2,3,4). Here we apply a reaction transport model (REMAP) (5) to data from ODP Site 1226 in the abyssal plain of the Eastern Equatorial Pacific (same location as Leg 138, Site 846). Our results suggest volumetric sulfate reduction rates vary from 346 fmol/cm3/day at 3 mbsf to 0.4 fmol/cm3/day in deeper sediments. Using existing cell counts, this implies csSRR between 10-3 and 10-6 fmol/cell/day, orders of magnitudes lower than those observed in shallower marine settings (10-1 to 10-4 fmol/cell/day) (6). We show that the observed S-isotopes are best explained with a constant fractionation factor of 48‰, considerably smaller than the 70‰ predicted by theoretical models (1). We hypothesize that this is due to in-situ sulfide re-oxidation and disproportionation, promoted by high contents of sedimentary Fe(III) and Mn(IV) at Site 1226 (7). We will further explore this hypothesis in our poster. Wing B.A. & Halevy I. Proc. Natl. Acad. Sci. USA 111, 18116-18125 (2014). Wortmann U.G. Geochem. Geophys. Geosyst. 7 (2006). Rudnicki M., Elderfield H. & Spiro B. Geochim. Cosmochim. Acta 65, 777-789 (2001). Tudge A.P. & Thode H.G. Canadian J. Res. 28, 567-578 (1950). Chernyavsky B.M. & Wortmann U.G. Geochem. Geophys. Geosyst. 8 (2007). Hoehler T.M. & Jørgensen B.B. Nature Rev. Microbiol. 11, 83-94 (2013). Gurvich E.G., Levitan M.A. & Kuzmina T.G. in Proc. of the Ocean Drilling Prog., Sci. Results, N. Pisias et al., Eds. (1995), vol. 138, pp. 769-778.

Multicenter study of pars plana vitrectomy for optic disc pit maculopathy: MACPIT study.

PubMed

Avci, R; Kapran, Z; Ozdek, Ş; Teke, M Y; Oz, O; Guven, D; Yilmaz, S; Kaderli, B; Durukan, A H; Sobaci, G; Unver, Y B; Akduman, L; Kaynak, S; Dogan, I; Inan, U U

2017-09-01

PurposeTo evaluate surgical intervention with pars plana vitrectomy (PPV) for correction of optic disc pit maculopathy (ODP-M).Patients and methodsRetrospective chart review from 13 centres of 51 eyes of 50 patients with ODP-M who underwent PPV between 2002-2014. Anatomic and final best-corrected visual acuity (BCVA) outcomes were evaluated for all cases with different adjuvant techniques.ResultsThere were 23 males and 27 females with median age 25.5 (6-68) years. Preoperative median foveal thickness was 694.5 (331-1384) μm and improved to 252.5 (153-1405) μm. Median BCVA improved from 20/200 (20/20000 to 20/40) to 20/40 (20/2000 to 20/20) with 20/40 or better in 31 eyes. Complete retinal reattachment was achieved in 44 eyes (86.3%) at 7.1 (5.9) months. The good surgical outcomes were achieved in different adjuvant groups. Median follow-up was 24 (6 to 120) months.ConclusionsThese results confirm the long-term effectiveness of PPV for ODP-M. Prospective studies are needed to determine the effectiveness of any adjuvant technique in improving the success of PPV for ODP-M.

Tufts submarine fan: turbidity-current gateway to Escanaba Trough

USGS Publications Warehouse

Reid, Jane A.; Normark, William R.

2003-01-01

Turbidity-current overflow from Cascadia Channel near its western exit from the Blanco Fracture Zone has formed the Tufts submarine fan, which extends more than 350 km south on the Pacific Plate to the Mendocino Fracture Zone. For this study, available 3.5-kHz high-resolution and airgun seismic-reflection data, long-range side-scan sonar images, and sediment core data are used to define the growth pattern of the fan. Tufts fan deposits have smoothed and filled in the linear ridge-and-valley relief over an area exceeding 23,000 km2 on the west flank of the Gorda Ridge. The southernmost part of the fan is represented by a thick (as much as 500 m) sequence of turbidite deposits ponded along more than 100 km of the northern flank of the Mendocino Fracture Zone. Growth of the Tufts fan now permits turbidity-current overflow from Cascadia Channel to reach the Escanaba Trough, a deep rift valley along the southern axis of the Gorda Ridge. Scientific drilling during both the Deep Sea Drilling Project (DSDP) and the Ocean Drilling Program (ODP) provided evidence that the 500-m-thick sediment fill of Escanaba Trough is dominantly sandy turbidites. Radiocarbon dating of the sediment at ODP Site 1037 showed that deposition of most of the upper 120 m of fill was coincident with Lake Missoula floods and that the provenance of the fill is from the eastern Columbia River drainage basin. The Lake Missoula flood discharge with its entrained sediment continued flowing downslope upon reaching the ocean as hyperpycnally generated turbidity currents. These huge turbidity currents followed the Cascadia Channel to reach the Pacific Plate, where overbank flow provided a significant volume of sediment on Tufts fan and in Escanaba Trough. Tufts fan and Tufts Abyssal Plain to the west probably received turbidite sediment from the Cascadia margin during much of the Pleistocene.

Synchronizing early Eocene deep-sea and continental records - cyclostratigraphic age models for the Bighorn Basin Coring Project drill cores

NASA Astrophysics Data System (ADS)

Westerhold, Thomas; Röhl, Ursula; Wilkens, Roy H.; Gingerich, Philip D.; Clyde, William C.; Wing, Scott L.; Bowen, Gabriel J.; Kraus, Mary J.

2018-03-01

A consistent chronostratigraphic framework is required to understand the effect of major paleoclimate perturbations on both marine and terrestrial ecosystems. Transient global warming events in the early Eocene, at 56-54 Ma, show the impact of large-scale carbon input into the ocean-atmosphere system. Here we provide the first timescale synchronization of continental and marine deposits spanning the Paleocene-Eocene Thermal Maximum (PETM) and the interval just prior to the Eocene Thermal Maximum 2 (ETM-2). Cyclic variations in geochemical data come from continental drill cores of the Bighorn Basin Coring Project (BBCP, Wyoming, USA) and from marine deep-sea drilling deposits retrieved by the Ocean Drilling Program (ODP). Both are dominated by eccentricity-modulated precession cycles used to construct a common cyclostratigraphic framework. Integration of age models results in a revised astrochronology for the PETM in deep-sea records that is now generally consistent with independent 3He age models. The duration of the PETM is estimated at ˜ 200 kyr for the carbon isotope excursion and ˜ 120 kyr for the associated pelagic clay layer. A common terrestrial and marine age model shows a concurrent major change in marine and terrestrial biota ˜ 200 kyr before ETM-2. In the Bighorn Basin, the change is referred to as Biohorizon B and represents a period of significant mammalian turnover and immigration, separating the upper Haplomylus-Ectocion Range Zone from the Bunophorus Interval Zone and approximating the Wa-4-Wa-5 land mammal zone boundary. In sediments from ODP Site 1262 (Walvis Ridge), major changes in the biota at this time are documented by the radiation of a second generation of apical spine-bearing sphenolith species (e.g., S. radians and S. editus), the emergence of T. orthostylus, and the marked decline of D. multiradiatus.

Tectonic erosion and consequent collapse of the Pacific margin of Costa Rica: Combined implications from ODP leg 170, seismic offshore data, and regional geology of the Nicoya Peninsula

USGS Publications Warehouse

Vannucchi, P.; Scholl, D. W.; Meschede, M.; McDougall-Reid, K.

2001-01-01

The convergent margin off the Pacific coast of the Nicoya Peninsula of Costa Rica exhibits evidence for subduction erosion caused by the underthrusting Cocos plate. Critical evidence for efficacy of this process was recovered at the Ocean Drilling Program (ODP) drilling Site 1042 (Leg 170), positioned ???7 km landward of the Middle America trench axis off the Nicoya Peninsula. The primary drilling objective at this site was to identify the age and origin of a regionally extensive and prominent seismic discontinuity, the so-called base-of-slope sediment (BOSS) horizon or surface. The BOSS horizon, which can be traced landward from near the trench to the Nicoya coastal area and parallel to it for hundreds of kilometers, separates a low-velocity (??? 2.0-2.5 km s-1) sequence of slope sediment, from an underlying sequence of much higher-velocity (> 4-4.5 km s-1) rock. Site 1042 reached the acoustically defined BOSS horizon at a below sea level depth of ??? 3900 m and yielded a carbonate-cemented calcarenitic breccia of early-middle Miocene age. Sedimentological, geochemical, paleontological, and cement paragenesis data document that the breccia accumulated in a shallow water depositional environment. On the basis of coastal exposures, the BOSS horizon, as a margin-wide geologic interface, can be temporally and lithostratigraphically correlated to a regional angular unconformity. This unconformity, known as the Mal Pais unconformity, separates Neogene and younger shelf-to-littoral beds from the underlying mafic units of the Mesozoic Nicoya Complex and Cretaceous and early Tertiary sedimentary sequences. At Site 1042 it is inferred that tectonism caused the vertical subsidence of the early Neogene breccia from a shallow to a deep water setting. The Mal Pais unconformity of the BOSS horizon thus connects the rock fabric of the outermost part of margin to that of coastal Nicoya and implies that in the early Neogene the Nicoya shelf extended seaward to near the present trench axis. This circumstance requires that the early Neogene trench axis was at least 50 km seaward of where it is now located. The long-term effects of subduction erosion, similar to those described for the scientifically drilled Japan, Tonga, and Peru margins, best account for offshore and onshore evidence for a post-Paleogene history of crustal thinning and landward trench migration of Costa Rica's Pacific margin. During the past 16-17 Myr the calculated mass removal and landward migration rates are 34-36 km3 Myr-1 km-1 of margin, and 3 km Myr-1, respectively. These values are similar to those found for other Pacific margins dominated by nonaccretionary subduction zone processes.

Plume-Ridge Interaction on the Cocos Plate (ODP Leg 205, Costa Rica): Implication for Fluid Circulation

NASA Astrophysics Data System (ADS)

Dreyer, B.; Chavagnac, V.; Font, L.; Morris, J.; Schramm, B.; Chavagnac, V.; Font, L.; Schramm, B.; Dreyer, B.; Morris, J. D.

2004-12-01

At subduction zone, the permeability and hydrology of the down-going igneous section play a key role on the behaviour of the seismogenic zone, which produces earthquake and tsunamis. We present, here, evidence of fluid circulation pathways in the igneous section being subducted at the Central American convergent margin (Site 1253 ODP Leg 205, Costa Rica). The geological evolution of the Cocos plate over the last 25 Ma is complicated as a result of plate boundaries re-arrangement (Silver et al., 1998). The Cocos-Nazca spreading centre (CNS) interacted with the Galapagos hotspot, which simultaneously deposited volcanic material on both side of the CNS, on the Cocos and Nazca plates. The oceanic crust of the Cocos and Nazca plates was formed along four spreading centres (Meschede et al., 1998) and the East Pacific Rise (EPR). The EPR oceanic crust has the featureless morphology and low-amplitude magnetic anomalies common to fast spreading ridge (Wilson & Hey, 1995) while the CNS oceanic crust presents a rough topography and high-amplitude magnetic anomalies (Wilson & Hey, 1995). We wish to focus on the ODP 1253 Site drilled in the Cocos plate because it samples the igneous input (rock, heat and fluid) to the Central American subduction zone. Coring at Site 1253 penetrated two separate igneous Units of which the upper one is a sill (Unit 4A) separated from the lower Unit (Unit 4B) by sediment. Both Unit 4A and 4B present similar texture, structure and mineralogy apart from the thin basaltic interval at 513 mbsf, below which Unit 4B becomes more glass-rich and altered. Unit 4B is either a sill complex with multiple intrusions related to the Galapagos volcanic activity or a series of thick slowly cooled lava flows formed at the EPR. Some of these characteristics of Unit 4B are similar to those seen in horizons recovered at Site 1256, which intersected thick-ponded lava flows. Analyses of marine magnetic anomalies indicate that the crust at Site 1253 was formed at EPR 25 Ma ago. However, its thermal gradients and conductivity yield surface heat flow anomalies of 10-40 mWm2, which is ˜70% lower than normal cooling lithosphere of that age (Fisher et al., 2003). Off-axis magmatic and tectonic activity associated with the formation of the Cocos Ridge may have increased fluid circulation pathways within the basement structure. Mobile trace element (Ba, Sr) and Sr isotope variations in conjunction with petrographic observation help identify horizons of fluid/rock interaction, e.g. fluid circulation pathways within Unit 4A and 4B. Based on veins, fractures, and void occurrences, the Unit 4A and 4B were subdivided into two and seven subunits respectively. Along the core-depth profile, mobile element concentrations and 87Sr/86Sr ratios vary mainly in a narrow range (0.703245 and 0.703503) but are still higher than those of EPR or the Galapagos hotspot (<0.703). At sub-unit interface, we observe drastic increases in Ba and Sr content and more radiogenic Sr isotope signature (up to 0.705106), especially above the thin basaltic horizon. This reflects exchange of Sr with seawater or hydrothermal fluids during alteration. Further work will determine fluid flux estimate at Site 1253. The origin, nature and structure of the oceanic crust at Site 1253 will be presented in two additional abstracts (see Dreyer and Moe, this session).

Paleoceanographic Inferences from Carbon and Nitrogen Isotopic Compositions of Cenomanian Black Shales from DSDP/ODP Sites 367, 530, 603, 641, 1257-1261, and 1276 in the Atlantic Ocean

NASA Astrophysics Data System (ADS)

Yum, J.; Meyers, P. A.; Bernasconi, S. M.; Arnaboldi, M.

2005-12-01

The mid-Cretaceous (Cenomanian- Turonian) was characterized as a peak global greenhouse period with highest sea level, highest CO2 concentration in atmosphere and low thermal gradients from the poles to the equator. The depositional environment of the organic-carbon-rich black shales that typify this period remains an open question. A total of 180 Cenomanian- Turonian core samples were selected from multiple ODP and DSDP sites in the Atlantic Ocean: 530 (Cape Basin), 603 (Hatteras Rise), 641 (Galicia Bank), 1257-1261 (Demerara Rise), 1276 (Newfoundland Basin). Total organic carbon and nitrogen concentrations and isotopic compositions were measured to investigate variations in the proto-Atlantic Ocean paleoceanographic conditions that contributed to the origin of the black shales for this period. These new data were combined with existing data from Sites 367 (Senegal Rise), 530, and 603. Both the black shales and the organic-carbon-poor background sediments (less than 1 percent) have carbon isotope values between -29 to -22 permil. The C/N ratios of the background sediments are low (less than 20) compared to those of the black shales (20-40). Nitrogen isotope values range from 0 to 4 permil in the background samples. All black shales have similarly low nitrogen isotope values that range between -4 to 0 permil. These exceptionally low values are inferred to reflect the productivity of blue green algae and cyanobacteria under strongly surface stratified oceanic conditions. Although carbon isotope and C/N values of black shales show almost similar patterns at each location, there are site-specific shifts in these data that could be related to the amount of continental run off and/or the effect of latitude. Our multi-site comparison suggests that specially stratified depositional environments that could produce and accumulate the abnormally high carbon concentrations in sediments occurred throughout the proto-Atlantic ocean during the mid-Cretaceous. However, regional factors affected the amount and origin of organic matter delivered to each location.

Shelf and open-ocean calcareous phytoplankton assemblages across the Paleocene-Eocene thermal maximum: Implications for global productivity gradients

USGS Publications Warehouse

Gibbs, S.J.; Bralower, T.J.; Bown, Paul R.; Zachos, J.C.; Bybell, L.M.

2006-01-01

Abrupt global warming and profound perturbation of the carbon cycle during the Paleocene-Eocene Thermal Maximum (PETM, ca. 55 Ma) have been linked to a massive release of carbon into the ocean-atmosphere system. Increased phytoplankton productivity has been invoked to cause subsequent CO2 drawdown, cooling, and environmental recovery. However, interpretations of geochemical and biotic data differ on when and where this increased productivity occurred. Here we present high-resolution nannofossil assemblage data from a shelf section (the U.S. Geological Survey [USGS] drill hole at Wilson Lake, New Jersey) and an open-ocean location (Ocean Drilling Program [ODP] Site 1209, paleoequatorial Pacific). These data combined with published biotic records indicate a transient steepening of shelf-offshelf trophic gradients across the PETM onset and peak, with a decrease in open-ocean productivity coeval with increased nutrient availability in shelf areas. Productivity levels recovered in the open ocean during the later stages of the event, which, coupled with intensified continental weathering rates, may have played an important role in carbon sequestration and CO2 drawdown. ?? 2006 Geological Society of America.

In-situ geophysical measurements in marine sediments: Applications in seafloor acoustics and paleoceanography

NASA Astrophysics Data System (ADS)

Gorgas, Thomas Joerg

Acoustic in-situ sound speeds and attenuation were measured on the Eel River shelf, CA, with the Acoustic Lance between 5 and 15 kHz to 2.0 meters below seafloor (mbsf). A comparison with laboratory ultrasonic geoacoustic data obtained at 400 kHz on cored sediments showed faster in-situ and ultrasonic sound speeds in coarse-grained deposits in water depths to 60 m than in fine-grained deposits below that contour line. Ultrasonic attenuation was often greater than in-situ values and remained almost constant below 0.4 mbsf in these heterogeneous deposits. In-situ attenuation decreased with depth. These observations partly agree with results from other field studies, and with theoretical models that incorporate intergranular friction and dispersion from viscosity as main controls on acoustic wave propagation in marine sediments. Deviations among in-situ and laboratory acoustic data from the Eel Margin with theoretical studies were linked to scattering effects. Acoustic Lance was also deployed in homogeneous, fine-grained sediments on the inner shelf of SE Korea, where free gas was identified in late-September, but not in mid-September 1999. Free gas was evidenced by an abrupt decrease of in-situ sound speed and by characteristic changes in acoustic waveforms. These results suggest the presence of a gassy sediment layer as shallow as 2 mbsf along the 70 m bathymetry line, and was attributed to a variable abundance of free gas on short-term and/or small-regional scales on the SE Korea shelf. Bulk density variations in marine sediments obtained along the Walvis Ridge/Basin, SW Africa, at Ocean Drilling Program (ODP) Sites 1081 to 1084 were spectral-analyzed to compute high-resolution sedimentation rates (SRs) in both the time- and age domains by correctly identifying Milankovitch cycles (MCs). SRs for the ODP sites yielded age-depth models that often correlate positively with biostratigraphic data and with organic mass accumulation rates (MAR Corg), a proxy for productivity, and negatively with Sea Surface Temperatures (SSTs), a proxy for wind strength. These results suggest that strong amplitudes of all main MCs existed for periods of high SRs and high MAR Corg and low SSTs, indicating a positive link between wind stress, upwelling vigor, productivity and insolation patterns in this area.

Planktic foraminiferal response to the Latest Danian Event in the Pacific Ocean (ODP Site 1210)

NASA Astrophysics Data System (ADS)

Jehle, Sofie; Bornemann, André; Deprez, Arne; Speijer, Robert

2015-04-01

During the Paleocene the marine ecosystem was disturbed by several transient climate events, e.g. the Dan-C2 (65.2 Ma), the Latest Danian Event (LDE, 61.75 Ma), and most known, the Paleocene-Eocene Thermal Maximum (PETM, 56 Ma). So far the LDE (or "Top Chron 27n Event") has rarely been studied in deep-sea sites with respect to the evolution and the paleoecology of planktic foraminifera. The event has already been described from Zumaia/Spain, Bjala/Bulgaria, Egypt, Shatsky Rise and Walvis Ridge. In the deep-sea the LDE is usually characterized by two distinctive Fe peaks in XRF core scanning data, paralleled by a prominent (~0.7 ‰) negative δ13C excursion (CIE) in benthic foraminifera (Westerhold et al., 2008, 2011). Benthic foraminiferal δ18O data from nearby ODP Site 1209 suggest a bottom-water temperature rise of ~2°C accompanying the negative CIE. Thus, the LDE has been considered as a further potential Paleocene "hyperthermal". Here we present data from ODP Site 1210 of the biotic response (planktic foraminifera assemblages), carbonate preservation as well as δ18O and δ13C isotope signals of the surface, subsurface and benthic taxa covering a time span of about 900 kyr around the LDE. Among others, it is mainly investigated to what extent the LDE influences the ocean ecology and especially the surface waters. Trends of both δ18O and δ13C of planktic and benthic foraminifera show negative shifts at the onset of the LDE. A 0.6‰ drop within 100 ky in planktic δ18O data suggest a temperature rise of ~2.5°C, whereas benthic foraminifera bottom water temperatures confirm a ~2°C rise like measured at Site 1209. δ13C variation is more abrupt and pronounced than the δ18O shift at the base of the LDE. The decreasing δ13C gradient between surface and subsurface dwelling foraminifera suggests a weaker and or shallower thermocline. Thermocline dwelling asymbiotic Parasubbotina rise in abundance simultaneously to the decrease in the δ13C gradient which may suggest that this taxon benefits from a shallower thermocline and, thus, increased stratification. After the event, photosymbiotic activity in surface dwellers like Morozovella might have been boosted due to less competitive pressure. Minor dissolution according to planktic foraminiferal fragmentation, P/B-ratios and coarse fraction is considered to be present during the LDE. This observation is consistent with a decrease in the total CaCO3 record, which drops from ~95% to 85%, while planktic foraminifera suffer a strong decrease in abundance from ~20,000 to ~1,000 speciemn per gram during the event. Results from Non-metric Multidimentional Scaling suggest distinct faunal changes between before, during and after the LDE. Prominent changes are especially the disappearance of Praemurica spp. shortly before or with the onset of the event, whereas Igorina albeari increases from 'few' to 'abundant' within the first Fe LDE peak. Morozovella angulata follows a slow but constant rise, while M. praeangulata has the opposite trend. Comparable obervations were done on genus level at the Tethys Ocean, Tunisia (Guasti et al., 2006). References Bornemann, A., Schulte, P., Sprong, J., Steurbaut, E., Youssef, M., Speijer, R.P., 2009. Latest Danian carbon isotope anomaly and associated environmental change in the southern Tethys (Nile Basin, Egypt). Journal of the Geological Society 166, 1135-1142. Guasti, E., Speijer, R.P., Brinkhuis, H., Smit, J., Steurbaut, E., 2006. Paleoenvironmental change at the Danian-Selandian transition in Tunisia: Foraminifera, organic-walled dinoflagellate cyst and calcareous nannofossil records. Marine Micropaleontology 59, 210-229. Westerhold, T., Röhl, U., Raffi, I., Fornaciari, E., Monechi, S., Reale, V., Bowles, J., Evans, H.F., 2008. Astronomical calibration of the Paleocene time. Palaeogegr. Palaeoclimatol. Palaeoecol. 257, 377-403. Westerhold, T., Röhl, U., Donner, B., McCarren, H.K., Zachos, J.C., 2011. A complete high-resolution Paleocene benthic stable isotope record for the central Pacific (ODP Site 1209). Paleoceanography 26, doi: 10.1029/2010pa002092.

Formation evaluation of gas hydrate-bearing marine sediments on the Blake Ridge with downhole geochemical log measurements

USGS Publications Warehouse

Collett, T.S.; Wendlandt, R.F.

2000-01-01

The analyses of downhole log data from Ocean Drilling Program (ODP) boreholes on the Blake Ridge at Sites 994, 995, and 997 indicate that the Schlumberger geochemical logging tool (GLT) may yield useful gas hydrate reservoir data. In neutron spectroscopy downhole logging, each element has a characteristic gamma ray that is emitted from a given neutron-element interaction. Specific elements can be identified by their characteristic gamma-ray signature, with the intensity of emission related to the atomic elemental concentration. By combining elemental yields from neutron spectroscopy logs, reservoir parameters including porosities, lithologies, formation fluid salinities, and hydrocarbon saturations (including gas hydrate) can be calculated. Carbon and oxygen elemental data from the GLT was used to determine gas hydrate saturations at all three sites (Sites 994, 995, and 997) drilled on the Blake Ridge during Leg 164. Detailed analyses of the carbon and oxygen content of various sediments and formation fluids were used to construct specialized carbon/oxygen ratio (COR) fan charts for a series of hypothetical gas hydrate accumulations. For more complex geologic systems, a modified version of the standard three-component COR hydrocarbon saturation equation was developed and used to calculate gas hydrate saturations on the Blake Ridge. The COR-calculated gas hydrate saturations (ranging from about 2% to 14% bulk volume gas hydrate) from the Blake Ridge compare favorably to the gas hydrate saturations derived from electrical resistivity log measurements.

Interpreting the paleo-redox record: Mn enrichment factors

NASA Astrophysics Data System (ADS)

Chun, C. O.; Delaney, M. L.

2006-12-01

Redox-sensitive metal enrichment factors (EF), have the ability to describe the redox chemistry of the overlying water and marine sediments at time of burial. Manganese (Mn) precipitates as Mn-rich oxyhydroxides in oxic environments, leading to sedimentary EF > 1 calculated relative to average continental crust as the presumed detrital source. Mn EF can also occur from source changes that are unrelated to redox changes. We compared bulk sediment digestions to sample splits treated with a reductive cleaning step prior to sediment digestion, to test whether the Mn EF are from oxyhydroxides. We measured sedimentary Mn EF for the past 30 m.y. for a Nazca Ridge site in the southeast Pacific (ODP Site 1237). The site is marked by a pronounced color change at 162 mcd, within an interval dominated by calcareous-rich lithology, prompting questions of source versus paleo-redox changes. Mn EF were measured across the Paleocene-Eocene Thermal Maximum (PETM) at three sites on Walvis Ridge in the southeast Atlantic (ODP Sites 1262, 1266, and 1263). The PETM global warming event leads to questions of redox changes. At Nazca Ridge Mn EF range from 10-70 prior to the change with decrease to crustal averages after the boundary. After two reductive cleanings on sediments exhibiting Mn EF >1, Mn EF were at crustal averages. Mn EF prior to the color change are oxyhydroxides and not a major input of detrital material. We suggest the color change represents a paleo-redox boundary, more oxygenated depositional setting prior to the change and more reducing depositional setting afterwards. Walvis Ridge PETM sections exhibit Mn EF values ranging between 4 and 12 prior to the warming, values at crustal averages during the warming, return to pre-event values in the recovery period. After the reductive cleaning procedure the deep (1262) and intermediate (1266) sites with Mn EF >1 before and after the warming event reduced to crustal averages with no change to Mn EF during the event. Bottom waters at those two sites were most likely oxygenated prior to the event, reducing at the onset of the warming, and returned to pre-event conditions in the recovery. Future studies of Mn EF as a paleo-redox indicator should include the reductive cleaning procedure to verify Mn-oxyhydroxides.

Design and analysis of group-randomized trials in cancer: A review of current practices.

PubMed

Murray, David M; Pals, Sherri L; George, Stephanie M; Kuzmichev, Andrey; Lai, Gabriel Y; Lee, Jocelyn A; Myles, Ranell L; Nelson, Shakira M

2018-06-01

The purpose of this paper is to summarize current practices for the design and analysis of group-randomized trials involving cancer-related risk factors or outcomes and to offer recommendations to improve future trials. We searched for group-randomized trials involving cancer-related risk factors or outcomes that were published or online in peer-reviewed journals in 2011-15. During 2016-17, in Bethesda MD, we reviewed 123 articles from 76 journals to characterize their design and their methods for sample size estimation and data analysis. Only 66 (53.7%) of the articles reported appropriate methods for sample size estimation. Only 63 (51.2%) reported exclusively appropriate methods for analysis. These findings suggest that many investigators do not adequately attend to the methodological challenges inherent in group-randomized trials. These practices can lead to underpowered studies, to an inflated type 1 error rate, and to inferences that mislead readers. Investigators should work with biostatisticians or other methodologists familiar with these issues. Funders and editors should ensure careful methodological review of applications and manuscripts. Reviewers should ensure that studies are properly planned and analyzed. These steps are needed to improve the rigor and reproducibility of group-randomized trials. The Office of Disease Prevention (ODP) at the National Institutes of Health (NIH) has taken several steps to address these issues. ODP offers an online course on the design and analysis of group-randomized trials. ODP is working to increase the number of methodologists who serve on grant review panels. ODP has developed standard language for the Application Guide and the Review Criteria to draw investigators' attention to these issues. Finally, ODP has created a new Research Methods Resources website to help investigators, reviewers, and NIH staff better understand these issues. Published by Elsevier Inc.

Hemispheric Symmetries of Plio-Pleistocene Surface Ocean Conditions: Insights from Southern Hemisphere ODP Sites 1125 and 1088

NASA Astrophysics Data System (ADS)

Lawrence, K. T.; Peterson, L.; Kelly, C.; Miller, H.; Seidenstein, J.

2013-12-01

For decades, most studies of Plio-Pleistocene climate and of the transition from the warmth of the Pliocene to the colder and more variable conditions of the Pleistocene have focused solely on northern hemisphere climate processes and responses. Here, we explore the southern hemisphere response to this major climate transition by documenting ocean surface conditions at Ocean Drilling Program Sites 1125 (42οS, 178οW, 1360m) and 1088 (40οS, 15οE, 2082m) through the Plio-Pleistocene. Secular trends in alkenone-derived sea surface temperature (SST) records indicate that these mid-latitude southern hemisphere sites cooled ~3-4οC over the past 3 Myrs, a magnitude comparable to sites located at similar latitudes in both the North Atlantic and North Pacific. This observation suggests that contraction of the low latitude warm pool was hemispherically symmetric. Our highly resolved (3 kyr resolution) Site 1125 SST record bears considerable structural similarity to SST records from nearby site 1123 (42οS,171οW) as well as sites 846 (3οS, 91οW) in the eastern equatorial Pacific and U1313 (41οN, 33οW) in the North Atlantic. Most of these SST records are dominated by 100k power and contain strong secondary 41k peaks throughout the past 3 million years. North Atlantic site U1313 is the exception, mirroring the shift in dominant periodicity from 41k to 100k associated with the mid-Pleistocene transition, that has long been observed in benthic oxygen isotope records. Finally, in southern hemisphere SST records as well as at site U1313 from the north Atlantic we observe weak precessional power that is not evident in benthic oxygen isotope record. These results suggest a fairly hemispherically-coordinated response of ocean surface temperature to changing global climate conditions during the Plio-Pleistocene in terms of both secular trends and dominant orbital frequencies.

Tectonics and geology of spreading ridge subduction at the Chile Triple Junction: a synthesis of results from Leg 141 of the Ocean Drilling Program

USGS Publications Warehouse

Behrmann, J.H.; Lewis, S.D.; Cande, S.C.

1994-01-01

An active oceanic spreading ridge is being subducted beneath the South American continent at the Chile Triple Junction. This process has played a major part in the evolution of most of the continental margins that border the Pacific Ocean basin. A combination of high resolution swath bathymetric maps, seismic reflection profiles and drillhole and core data from five sites drilled during Ocean Drilling Program (ODP) Leg 141 provide important data that define the tectonic, structural and stratigraphic effects of this modern example of spreading ridge subduction. A change from subduction accretion to subduction erosion occurs along-strike of the South American forearc. This change is prominently expressed by normal faulting, forearc subsidence, oversteepening of topographic slopes and intensive sedimentary mass wasting, overprinted on older signatures of sediment accretion, overthrusting and uplift processes in the forearc. Data from drill sites north of the triple junction (Sites 859-861) show that after an important phase of forearc building in the early to late Pliocene, subduction accretion had ceased in the late Pliocene. Since that time sediment on the downgoing oceanic Nazca plate has been subducted. Site 863 was drilled into the forearc in the immediate vicinity of the triple junction above the subducted spreading ridge axis. Here, thick and intensely folded and faulted trench slope sediments of Pleistocene age are currently involved in the frontal deformation of the forearc. Early faults with thrust and reverse kinematics are overprinted by later normal faults. The Chile Triple Junction is also the site of apparent ophiolite emplacement into the South American forearc. Drilling at Site 862 on the Taitao Ridge revealed an offshore volcanic sequence of Plio-Pleistocene age associated with the Taitao Fracture Zone, adjacent to exposures of the Pliocene-aged Taitao ophiolite onshore. Despite the large-scale loss of material from the forearc at the triple junction, ophiolite emplacement produces a large topographic promontory in the forearc immediately after ridge subduction, and represents the first stage of forearc rebuilding. ?? 1994 Springer-Verlag.

Testing the ``Wildfire Hypothesis:'' Terrestrial Organic Carbon Burning as the Cause of the Paleocene-Eocene Boundary Carbon Isotope Excursion

NASA Astrophysics Data System (ADS)

Moore, E. A.; Kurtz, A. C.

2005-12-01

The 3‰ negative carbon isotope excursion (CIE) at the Paleocene-Eocene boundary has generally been attributed to dissociation of seafloor methane hydrates. We are testing the alternative hypothesis that the carbon cycle perturbation resulted from wildfires affecting the extensive peatlands and coal swamps formed in the Paleocene. Accounting for the CIE with terrestrial organic carbon rather than methane requires a significantly larger net release of fossil carbon to the ocean-atmosphere, which may be more consistent with the extreme global warming and ocean acidification characteristic of the Paleocene-Eocene Thermal Maximum (PETM). While other researchers have noted evidence of fires at the Paleocene-Eocene boundary in individual locations, the research presented here is designed to test the "wildfire hypothesis" for the Paleocene-Eocene boundary by examining marine sediments for evidence of a global increase in wildfire activity. Such fires would produce massive amounts of soot, widely distributed by wind and well preserved in marine sediments as refractory black carbon. We expect that global wildfires occurring at the Paleocene-Eocene boundary would produce a peak in black carbon abundance at the PETM horizon. We are using the method of Gelinas et al. (2001) to produce high-resolution concentration profiles of black carbon across the Paleocene-Eocene boundary using seafloor sediments from ODP cores, beginning with the Bass River core from ODP leg 174AX and site 1209 from ODP leg 198. This method involves the chemical and thermal extraction of non-refractory carbon followed by combustion of the residual black carbon and measurement as CO2. Measurement of the δ 13C of the black carbon will put additional constraints on the source of the organic material combusted, and will allow us to determine if this organic material was formed prior to or during the CIE.

Major early Eocene carbon cycle perturbations and changes in planktic foraminiferal assemblages from the southeast Atlantic Ocean (ODP Site 1263)

NASA Astrophysics Data System (ADS)

Luciani, Valeria; D'Onofrio, Roberta; Dickens, Gerald Roy; Wade, Bridget

2017-04-01

On a paleoclimatic perspective the early Paleogene represents one of the most interesting and dynamic intervals of the Earth's history. Present record indicates that the Earth climate system reached its Cenozoic maximum peak of global warming and probably of pCO2 during the early Eocene climatic optimum (EECO, 49-53 Ma). Superimposed to the general trend, our planet experienced short-term ( 40-200 kyr) repeated peaks in global temperatures and major changes in the carbon cycle, known as hyperthermals. Great scientific interest has been focused on the early Paleogene hyperthermal events, given the assumed similarity with the current climatic scenario. Less attention has been dedicated to the EECO long lasting perturbation of extraordinary warming thus many characters of this interval still remain largely unconstrained, especially as for the biotic response. We present here results on early Eocene planktic foraminiferal analysis from the southeast Atlantic Ocean Drilling Program (ODP) Site 1263 (Walvis Ridge, Leg 208) to explore possible relationship between changes in assemblages and carbon cycle perturbation. The time interval is of particular interest for an abrupt switch occurred at low-latitude of the northern hemisphere between two important calcifiers of the tropical-subtropical early Paleogene oceans, the genera Morozovella and Acarinina at the carbon isotopic excursion known as J event, at the EECO onset. Precisely, the relative abundance of Morozovella permanently decreased by at least half, along with a progressive decrease in the number of species. Concomitantly, Acarinina almost doubled its abundance and diversified. Site 1263 was located during the early Eocene at a latitude of 40° south therefore representing a temperate setting of southern hemisphere not yet explored for planktic foraminiferal changes. We document a permanent decrease in Morozovella abundance at the beginning of the EECO, although this decline is delayed by 165 kyr with respect to the low-latitudes of the northern hemisphere. We suppose that that this delay can be explained with a temporary migration of the warm water morozovellids southwards at the initiation of EECO warmth, but suffering consequently of the unfavourable environmental conditions triggered by the persistent EECO perturbation. Our data confirm that the Acarinina over Morozovella turnover was global and related to the EECO rather than local factors, even though the triggering mechanisms still remain elusive. We speculate that competition in the mixed-layer played a significant role in the switch in abundance that favoured Acarinina over Morozovella at the beginning of the EECO. A competition between the two genera is deducible by their anti-phase variations in abundances recorded at the early Paleogene hyperthermals in different settings and confirmed for Site 1263. In addition, we document at Site 1263 the virtual disappearance within the EECO of the biserial chiloguembelinids, commonly considered as inhabiting the Oxygen Minimum Zone, and a certain reduction in abundance of the thermocline-dweller subbotinids as a result ecological niches contraction. The significant and permanent modifications recorded by the foraminiferal assemblages at Site 1263 emphasize the prominent effect of the long-lasted EECO perturbation that superimposed and prevailed on the ephemeral changes linked to the early Eocene hyperthermals.

Late Miocene to Pleistocene Mineralogy of ODP Site 1146

NASA Astrophysics Data System (ADS)

Arnold, E. M.

2001-12-01

ODP Site 1146 (19° 27.40'N, 116° 16.37'E, 2092 m depth) was drilled on the continental slope of the South China Sea. A composite section, comprised of three stratigraphic units, extends down to 640 mcd. Unit 1 is late Pliocene to Pleistocene nannofossil clay (0 - 243 mcd); Unit 2, middle Miocene to Late Pliocene foraminifera - nannofossil - clay mixed sediment (243 - 553 mcd); Unit 3, early to middle Miocene nannofossil clay (553 - 642 mcd). This study reports the < 2 μ m mineralogy from the late Miocene through early Pleistocene. Samples were analyzed at approximately 1.5 m intervals from 150 to 225 mcd, and 1 m intervals from 225 to 440 mcd, with an age resolution of ~25 ka and ~35 ka, respectively. Illite, chlorite, quartz and plagioclase concentrations decrease with increasing depth through Unit 1. Kaolinite and calcite concentrations increase with depth, while smectite values are constant in this unit. Illite, quartz and plagioclase show high variability in Unit 1 compared with the underlying Unit 2. Unit 2 has more uniform sediment composition, with constant illite, chlorite, and quartz concentrations. Kaolinite concentration increases with depth, following a drop in concentration across the Unit 1/2 boundary. Plagioclase concentration shows a small, steady decrease throughout this unit. Smectite concentration does not change across the Unit 1/2 boundary, decreases to a steady low value from 310 - 400 mcd, and increases again towards the bottom. The mineralogy of sediments recovered at Site 1146 suggest a classic pattern of source region aridification from the middle Pliocene through the Pleistocene, indicated in Unit 1 mineralogy as a decrease in kaolinite with decreasing depth, concomitant with an increase in quartz, plagioclase, illite and chlorite. The mineral variability in this interval suggests glacial - interglacial control of the terrigenous sedimentation. The sediment sources and source area weathering regimes were relatively constant throughout Unit 2, as indicated by low mineral variability and relatively constant mineral concentrations.

The NEPTUNE Canada Seismograph Network

NASA Astrophysics Data System (ADS)

Rogers, G. C.; Meldrum, R.; Baldwin, R.; Rosenberger, A.; Mulder, T.

2009-12-01

NEPTUNE Canada is the world’s first large regional cable-linked, multi-disciplinary scientific seafloor observatory. In the fall of 2007 an 800 kilometer ring of powered fibre optic cable was laid on the seafloor over the northern part of the Juan de Fuca plate and connected to a shore facility near Port Alberni on Vancouver Island. Five nodes were attached to the cable in the early in the summer of 2009 paving the way for junction boxes and scientific instruments installed in the late summer and fall. The NEPTUNE Canada Seismograph Network will consist initially of four broadband and four short period seismic systems. In the summer of 2009, three broadband OBS packages were deployed forming a large triangle with apexes at ODP 1027 in mid plate and two sites on the continental slope, ODP 889 and Barkley Canyon. In summer 2010 an additional broadband package will be installed on the Endeavour segment of the Juan de Fuca Ridge, and four short period instruments will be installed nearby forming a small array, 6 km in maximum dimension, to record earthquake activity in the vicinity of the many multidisciplinary ridge experiments. The broadband systems comprise a broadband seismometer and strong motion accelerometer in a surficially buried spherical titanium case, with a current meter, hydrophone and differential pressure gauge deployed nearby. The short period systems will include 3-component corehole seismometers on long term loan from the Monterey Bay Aquarium Research Institute (MBARI). All systems will have backup capacity for modest cable outages. The NEPTUNE Canada Seismograph Network relies heavily on knowledge gained from the previous seismographs temporarily deployed in the region by MBARI and the University of Washington and will re-occupy the broadband site and three short period sites at the ridge. NEPTUNE Canada seismic data will be archived by, and available from, both the Geological Survey of Canada and IRIS.

Oceans of Opportunity: Partnerships to Increase Minority Student Involvement in the Marine Geosciences

NASA Astrophysics Data System (ADS)

Pride, C.; Christensen, B.

2007-12-01

The Oceans of Opportunity program to increase involvement of traditionally under-represented students in the marine geosciences is in its final phase of track 1 funding from NSF. The program employs a tiered approach to research, teaching and outreach activities to enhance the K-12 to graduate pipeline. Partner institutions include Savannah State University, an HBCU in coastal Georgia; Adelphi University serving a minority population from NYC; the Georgia State University Bio-Bus serving the metro-Atlanta area; and the Joint Oceanographic Institutions. The Oceans of Opportunity education pipeline includes 1) service learning activities implemented by SSU marine science majors in partner public schools with high minority enrollment; 2) outreach by the Georgia State University Bio-Bus to Savannah area schools; 3) expansion of the SSU geoscience curriculum; and 4) development of activities based on models of ODP cores for use in both outreach and college teaching. Service learning through SSU classes has permitted contact with a large number of K-12 students. More than 1000 predominantly African-American K-12 students completed hands-on lessons on plate tectonics and plankton contributors to marine sediments in the two years of this program under the guidance of HBCU science majors. Lessons on use of the marine sediment and fossil record as proxies in paleoclimatic studies using replicas of ODP cores were delivered to 600 students in the Savannah school system and about 2000 visitors to the Georgia Aquarium in Atlanta. The marine geoscience lessons delivered at the high school level resulted in greater test score improvement when the topic had already been thoroughly introduced by the teacher. A survey of science attitudes of the high school students (n=419) indicates African-American high school students have low levels of enjoyment of and interest in the sciences. In addition, more female than male African-American students are enrolling in science courses and intend to become science majors. The geosciences fared worse than most other STEM fields with most college-bound students saying that they did not intend on taking a geoscience course in college. We established Research Training Groups (RTGs) including undergraduate and graduate students focusing on 1) Georgia shelf, estuarine and marsh dynamics, and 2) South African Pleistocene paleoceanography. Collaborative projects between SSU and Adelphi during the course of this program have engaged 12 students (75% minority) in research on shelf and salt marsh micropaleontology and sedimentation, diatoms in modern estuarine environments, and South African paleoclimate using ODP records. RTG students have also developed a marine sediment repository at SSU, participated in field excursions and research cruises, and presented their research at conferences.

Deep To Shallow, Time Transgressive Shift In The Source Of Bottom Waters On Demerara Rise Inferred From Neodymium Isotopes In Fish Debris

NASA Astrophysics Data System (ADS)

Isaza-Londoño, C.; MacLeod, K. G.; Martin, E. E.; Jiménez Berrocoso

2008-12-01

Between the Campanian and Danian, ɛNd values of fish debris from four sites on Demerara Rise (tropical North Atlantic) shift by ~5 units from -16 to -11. Low values from Campanian and early Maastrichtian samples are similar to values measured on most other Late Cretaceous samples from Demerara sites, whereas the post-shift values are similar to Late Cretaceous and Paleogene values observed at a number of other North Atlantic deep sea sites. In addition, at the two relatively deep sites studied (Ocean Drilling Program [ODP] Sites 1258 and 1260), the shift begins near the base of the Maastrichtian Abathomphalus mayaroensis planktonic foraminifera Zone and values increase over an interval representing several million years of deposition. In two relatively shallow sites (OSP Sites 1259 and 1261), on the other hand, ɛNd values remain low through the highest Cretaceous samples measured, which are from near the top of the Abathomphalus mayaroensis Zone. Therefore, low values persist for several million years longer at the shallower sites. At Site 1259, no Paleogene samples have been analyzed yet, but at Site 1261 values shift from ~-16.5 to ~-13 in samples separated by ~3.5 m and bracketing the Cretaceous/Paleogene (K/T) boundary. Unfortunately, the K/T boundary is not complete at Site 1261, so the relationship to the K/T event is unclear. Ongoing work is focused on constraining the relationship between ɛNd shifts and the K/T boundary using the more complete record at Site 1259 and at examining whether there is any high frequency variation superimposed on the gradual trends observed, especially at the deeper sites. Regardless of the outcome of the these analyses, assuming the low ɛNd values characteristic of most the Late Cretaceous on Demerara Rise are the signature of a locally formed intermediate water mass, the existing data already indicate that the importance of downwelling in the tropical North Atlantic began to wane in the mid- Maastrichtian and had apparently ceased by the earliest Paleogene.

Magma source evolution beneath the Caribbean oceanic plateau: New insights from elemental and Sr-Nd-Pb-Hf isotopic studies of ODP Leg 165, Site 1001 basalts

NASA Astrophysics Data System (ADS)

Kerr, A. C.; Pearson, G.; Nowell, G.

2008-12-01

Ocean Drilling Project Leg 165 sampled 38m of the basaltic basement of the Caribbean plate at Site 1001 on the Hess Escarpment. The recovered section consists of 12 basaltic flow units which yield a weighted mean Ar-Ar age of 80.9±0.9 Ma (Sinton et al., 2000). The basalts (6.4-8.5 wt.% MgO) are remarkably homogeneous in composition and are more depleted in incompatible trace elements than N-MORB. Markedly, depleted initial radiogenic isotope ratios reveal a long-term history of depletion. Although the Site 1001 basalts are superficially similar to N-MORB, radiogenic isotopes in conjunction with incompatible trace element ratios show that the basalts have more similarity to the depleted basalts and komatiites of Gorgona Island. This chemical composition strongly implies that the Site 1001 basalts are derived from a depleted mantle plume component and not from depleted ambient upper mantle. Therefore the Site 1001 basalts are, both compositionally and tectonically, a constituent part of the Caribbean oceanic plateau. Mantle melt modelling suggests that the Site 1001 lavas have a composition which is consistent with second-stage melting of compositionally heterogeneous mantle plume source material which had already been melted, most likely to form the 90Ma basalts of the plateau. The prolonged residence (>10m.y.) of residual mantle plume source material below the region, confirms computational model predictions and places significant constraints on tectonic models of Caribbean evolution in the late Cretaceous, and the consequent environmental impact of oceanic plateau volcanism. Reference Sinton, C.W., et al., 2000. Geochronology and petrology of the igneous basement at the lower Nicaraguan Rise, Site 1001. Proceedings of the Ocean Drilling Program, Scientific Results. Leg 165. pp. 233-236.

Glacial-interglacial variations in sediment organic carbon accumulation and benthic foraminiferal assemblages on the Bermuda Rise (ODP Site 1063) during MIS 13 to 10

NASA Astrophysics Data System (ADS)

Poli, Maria Serena; Meyers, Philip A.; Thunell, Robert C.; Capodivacca, Marco

2012-09-01

We have determined organic carbon concentrations and isotopic compositions and benthic foraminiferal assemblages in sediments deposited between ˜500 and 340 ka at ODP Site 1063 on the northeastern flank of the Bermuda Rise. This time interval includes Marine Isotope Stage (MIS) 11, a particularly warm and long interglacial that was similar to today, and MIS 12, one of the most severe glacials of the last 600 kyr. During MIS 11.3, the peak of interglacial warming, organic carbon accumulation rates are low and benthic foraminiferal assemblages are dominated by Nuttallides umbonifera, a species indicative of oligotrophic environments. Higher accumulation rates during MIS 12 and 10 correspond with elevated sedimentation rates (33-36 cm/kyr). This pattern implies a combination of enhanced delivery and improved preservation of sediment organic matter during these glacial times. Organic δ13C values are less negative during MIS 12 and MIS 10 than during MIS 11, which is consistent with greater glacial-stage marine productivity. High relative abundances ofOridorsalis umbonatus during glacial intervals probably records a low but sustained flux of highly degraded organic material. Large, recurrent fluctuations in the abundance of Epistominella exiguaat the beginnings of the MIS 12 and MIS 10 glaciations suggest a marked increase in local phytoplankton blooms at these times and consequent delivery of phytodetritus to the seafloor. The most likely causes of these variations are changes in the position and strength of the Gulf Stream and its associated cold-ring eddies, combined with increased advection of terrigenous sediments from northerly locations during glacial lowstands.

An Early Pleistocene 190 kyr pollen record from the ODP Site 976, Western Mediterranean region

NASA Astrophysics Data System (ADS)

Joannin, Sebastien; Combourieu Nebout, Nathalie

2010-05-01

The Mid-Pleistocene Transition (1.200 to 0.500 Ma) corresponded to a period of increased cooling and the shift from "41 kyr world" to "100 kyr world". Climate cycles were 41 kyr long as a response of the climate system to the obliquity orbital parameter forcing, then the climate system responded to a combination of eccentricity and precession resulting in 100 kyr long cycles. The Mediterranean region offers the opportunity to study climate response to orbital forcing at this particular period. It is usually done on marine proxies that are preserved in continuous sediments with good age attributions but may be affected by calorific inertia of marine environments. We investigate continental palaeoenvironment changes inferred from pollen analyses through time on a short interval of the ODP Site 976 (259.50 to 230.42 mcd). In order to search for short climate oscillations, the chronology has been refined according to the comparison between the pollen ratio "mesothermic vs. Caryophyllaceae, Amaranthaceae-Chenopodiaceae and steppe elements" curve and Mediterranean and LR04 oxygen isotope curves. The time slice runs from ~1.090 Ma (MIS 31) to ~0.900 Ma (MIS 23). Pollen analyses provide a new record of the south western Mediterranean vegetation and climate changes at the beginning of the Mid-Pleistocene Transition. Vegetation successions are evidenced in pollen diagram with replacement of mesothermic elements by mid- and high-altitude trees, ended by strengthening of Caryophyllaceae, Amaranthaceae-Chenopodiaceae, and steppe vegetation. These vegetation successions reveal two overlapping rhythms that may be related to climate responses to both obliquity and precession orbital parameters, while wavelet analyses on pollen ratio only indicate the shift from precession to obliquity dominance. The comparison of these two approaches raised the question of their own limit.

Radiolarian Indices of Paleoproductivity Variation in the late Pleistocene Benguela Upwelling System, ODP Site 1084

NASA Astrophysics Data System (ADS)

Bittniok, B. B.; Lazarus, D. B.; Diester-Haass, L.; Billups, K.; Meyers, P.

2006-12-01

Changes in export productivity play a significant role in ocean carbon budgets and global climate change. Proxies for export productivity can be difficult to interpret: benthic foraminifera accumulation rates (BFAR) can be affected by carbonate dissolution in organic-carbon rich sediments; bulk opal can be affected by silica limitation of source waters. Recent work (Lazarus et al. 2006; Mar. Micropal.) has shown that a new index based on radiolarian faunal changes (WADE ratio) correlates well to total organic carbon (TOC) values from the same samples over the long term (latest Miocene-Recent) history of productivity in the Benguela Upwelling System (BUS). We present new data on variation in export productivity proxies (WADE, TOC, carbonate, radiolarian opal, BFAR) for the last glacial-interglacial cycle from ODP Site 1084, located just offshore from the main coastal upwelling cells of the BUS. Our age model, from mean Quaternary sedimentation rates (Leg 175 Scientific Results), is in accordance with cyclic variation in other climate sensitive parameters (carbonate and color reflectance). Although opal content and radiolarian preservation is only moderate in our samples, WADE values vary significantly and suggest higher productivity during the last glacial, in accordance with current interpretations of BUS history. Radiolarian opal accumulation is also higher during the last glacial, suggesting that silica limitation (opal paradox) conditions did not dominate over this time period. Similar results for bulk opal have been reported from late Quaternary piston cores from the more northerly Congo upwelling region (Schneider et al, 1997; Paleoc.). We conclude that WADE ratios are a useful proxy for late Pleistocene productivity in the BUS at glacial- interglacial time scales.

The Early Miocene Climatic Optimum (18-16 Ma): Stable Isotope and Mg/Ca Records from ODP Leg 189 Site 1168.

NASA Astrophysics Data System (ADS)

Syed, S.; Pekar, S.

2008-12-01

Ice volume estimates for the late early Miocene (~18-16 Ma) were derived from paired oxygen isotope records and Mg/Ca ratios from ODP Site 1168, which is located on the southwest slope of Tasmania. These records indicate the presence of a dynamic ice sheet in Antarctica, with ice-volume estimates up to present day levels occurring with relatively warm bottom water temperatures during isotope events Mi1b (17.9-17.6 Ma) and Mi2 (16.2 Ma). These records also indicate ice-volume decreased significantly during the Early Miocene Climatic Optimum ~17.2 to 16.4 Ma suggesting a near complete collapse of the East Antarctic Ice Sheet, based on an approximately 1‰ decrease in oxygen isotope value of seawater. Bottom water temperatures (BWT) derived from Mg/Ca ratios indicate temperature varied from ~8°C to 3°C, during the early Miocene, with the warmest BWT's occurring during glacial maxima and lowest occurring during glacial minima. Mg/Ca records from other records also indicate ice-volume increases coinciding with deep sea warming. These records suggest Antarctic glaciation may have been influenced by the moisture input by warm saline deep waters (WSDW) originating from the Indian Ocean/Tethys Sea. These WSDW would become entrained and ultimately upwell near Antarctica, resulting in delivering increased moisture/snowfall and therefore increased ice volume on the Antarctic continent. However, an alternative interpretation of the records could be that temperature estimates derived from Mg/Ca ratios may be over estimating the magnitude of temperature changes, thus resulting in an overestimation of ice-volume changes.

Evolution of Heat Flow with Age on the Southern Flank of the Costa Rica Rift

NASA Astrophysics Data System (ADS)

Kolandaivelu, K. P.; Harris, R. N.; Lowell, R. P.; Wilson, D. J.; Hobbs, R. W.

2017-12-01

Analysis of 67 new conductive heat flow measurements at five sites ranging between ≈ 1.6 and 5.7 Ma on the southern flank of the Costa Rica Rift yields insight into factors that influence hydrothermal circulation in young oceanic crust. The heat flow measurements were collocated with a high-resolution multi-channel seismic line, extending from the ridge axis to ODP hole 504B. The mean conductive heat flow, qobs, 80 mWm-2, is ≈ 25% of the mean lithospheric heat flux, qth, predicted by half-space conductive cooling model. The ratio qobs/qth varies significantly from site to site indicating that advective heat loss may be influenced by the presence of high-angle, ridge-ward dipping normal faults, surface topography, and sediment thickness, which vary significantly along the profile. The 1.6 Ma heat flow site, which is located between two outcrops separated by 2 km and has thin sediment cover, yields qobs/qth » 0.08. The advective heat loss indicates a mass flux of 3 x 10-5 kgm-2s-1 and upper crustal permeabilities of 4 x 10-11 and 3 x 10-9 m2 for 1000 m and 100 m aquifer thicknesses, respectively. At the 2.6 Ma site with 75 m sediment cover, qobs/qth » 0.18 and heat flow is uniformly low, except for one high value near a fault. At the 3.5 Ma site, qobs/qth » 0.15. The heat flow deficit results from outcrop to outcrop flow, but subcritical cellular convection driven by local basement topography produces small heat flow highs and lows superimposed on the overall trend. At the 4.5 Ma site, qobs/qth » 0.06. The heat flow distribution indicates that discharge occurs through a large, thinly-sedimented topographical high, where estimated mass flux is 3 x 10-5 kgm-2s-1. At the oldest site of 5.7 Ma, qobs/qth » 1, but some heat flow values greater than qth occur near sparsely-sedimented basement outcrops, suggesting redistribution of heat by subsurface convection controlled by basement topography, similar to ODP Hole 504B. That qobs/qth » 1 at a much younger age than indicated by global data suggests that basement burial under a thick sediment cover inhibits advective heat loss through the crust. These data were collected as part of a major interdisciplinary NERC and NSF-funded collaboration entitled: Oceanographic and Seismic Characterization of heat dissipation and alteration by hydrothermal fluids at an Axial Ridge (OSCAR).

Plio-Pleistocene Sea Surface Temperature Variability As Measured by Different Proxies - A Cautionary Tale

NASA Astrophysics Data System (ADS)

Lawrence, K. T.; Woodard, S. C.; Castañeda, I. S.; deMenocal, P. B.; Peterson, L.; Rosenthal, Y.; Bochner, L.; Gorbey, D. B.; Mauriello, H.

2016-12-01

Conflicting interpretations from the application of different sea surface temperature (SST) proxies seeking to characterize past climate conditions of the same region have given rise to a number of controversies about key elements of Pliocene climate. Thus, a detailed look at whether or not different temperature proxies yield consistent results is warranted. Here, we examine Pliocene climate variability at the orbital scale reporting new alkenone-derived SST estimates from ODP Site 1088 (South Atlantic) and ODP Site 846 (Eastern Equatorial Pacific). Using these novel datasets and previously published records from a variety of different sites in a variety of localities, we further examine the consistency of Plio-Pleistocene SST variability and orbital signatures from faunal, Mg/Ca, and TEX86 SST records relative to Uk'37 SST records. We find that many companion SST records produce very similar mean trends and standard deviations as well as absolute temperature estimates that are generally within error of each other. Our analysis also suggests that many companion records, with a few notable exceptions, capture the same dominant Milankovitch periodicities and produce phase estimates relative to benthic oxygen isotope estimates that are within error of each other. However, marked structural differences occur between different proxy records on glacial-interglacial timescales in Uk'37 versus Mg/Ca comparisons and some Uk'37 versus TEX86 comparisons. Therefore, the temperature estimates of individual glacial-interglacial cycles may vary significantly when a specific time slice is explored. Our preliminary investigation suggests that whether or not climate records derived from different paleothermometers yield consistent results depends on the timescale being explored and the study site, which reflects key factors such as seasonality, ecology, and diagenetic regime. Additional work that explores the underlying causes of the differences observed among proxies and uses a more systematic approach to directly compare the results from different paleothermometers is required. Until we have a better and broader sense of where/when proxies perform consistently, we recommend caution in treating SST records from different proxies as interchangeable.

Radiolaria and pollen records from 0 to 50 ka at ODP Site 1233: Continental and marine climate records from the Southeast Pacific

USGS Publications Warehouse

Pisias, N.G.; Heusser, L.; Heusser, C.; Hostetler, S.W.; Mix, A.C.; Weber, M.

2006-01-01

Site 1233 drilled during Leg 202 of the Ocean Drilling Program provides a detailed record of marine and continental climate change in the Southeast Pacific and South American continent. Splits from over 500 samples taken at 20 cm intervals for quantitative analysis of radiolarian and pollen populations yield a temporal resolution of 200-400 years. In each sample, 39 pollen taxa and 40 radiolarian species and genera were evaluated. Age control is provided by 25 AMS 14C dates [Lamy, F., Kaiser, J., Ninnemann, U., Hebbeln, D., Arz, H.W., Stoner, J., 2004. Science 304, 1959-1962]. Multivariate statistical analyses of these data allow us to conclude the following: (1) During the past 50 ka, the region of the central Chile coast is not directly influenced by polar water from the Antarctic region. (2) Changes in ocean conditions off central Chile during this time interval primarily reflect north-south shifts in the position of the South Pacific transition zone. (3) Changes in Chilean vegetation reflect comparable latitudinal shifts in precipitation and the position of the southern westerlies. (4) The first canonical variate of radiolarian and pollen records extracted from Site 1233 are remarkably similar to each other as well as to temperature records from the Antarctic, which suggests that marine and continental climate variability in the region is tightly coupled at periods longer than 3000 years. (5) The phase coupling of these climate records, which lead variations of continental erosion based on iron abundance at the same site, are consistent with a hypothesis that erosion is linked to relatively long (i.e, few thousand years) response times of the Patagonian ice sheet, and thus is not a direct indicator of regional climate. ?? 2005 Elsevier Ltd. All rights reserved.

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)

Rack, Frank

2003-06-30

The primary accomplishments of the JOI Cooperative Agreement with DOE/NETL in this quarter were that: (1) Frank Rack, Anne Trehu, and Tim Collett presented preliminary results and operational outcomes of ODP Leg 204 at the American Association of Petroleum Geologists annual meeting in Salt Lake City, UT; (2) several Leg 204 scientists participated in special hydrate sessions at the international EGS/AGU/EUG meeting in Nice, France and presented initial science results from the cruise, which included outcomes arising from this cooperative agreement; and, (3) postcruise evaluation of the data, tools and measurement systems that were used during ODP Leg 204 continuedmore » in the preparation of deliverables under this agreement. At the EGS/EUG/AGU meeting in Nice, France in April, Leg 204 Co-chiefs Anne Trehu and Gerhard Bohrmann, as well as ODP scientists Charlie Paull, Erwin Suess, and Jim Kennett, participated in a press conference on hydrates. The well-attended press conference entitled ''Gas Hydrates: Free methane found and controversy over the 'hydrate gun''' led to stories in Nature on-line and BBC radio, among others. There were six (6) oral and fifteen (15) poster presentations on ODP Leg 204 hydrate science at the EGS/AGU/EUG Meeting in Nice, France on April 6-11, 2003. This was a very strong showing at a meeting just over six month following the completion of the drilling cruise and highlighted many of the results of the leg, including the results obtained with instruments and equipment funded under this cooperative agreement. At the AAPG annual meeting in Salt Lake City, UT on May 11-14, 2003, Anne Trehu gave an oral presentation about the scientific results of Leg 204, and Frank Rack presented a poster outlining the operational and technical accomplishments. Work continued on analyzing data collected during ODP Leg 204 and preparing reports on the outcomes of Phase 1 projects as well as developing plans for Phase 2.« less

Integrated NMR Core and Log Investigations With Respect to ODP LEG 204

NASA Astrophysics Data System (ADS)

Arnold, J.; Pechnig, R.; Clauser, C.; Anferova, S.; Blümich, B.

2005-12-01

NMR techniques are widely used in the oil industry and are one of the most suitable methods to evaluate in-situ formation porosity and permeability. Recently, efforts are directed towards adapting NMR methods also to the Ocean Drilling Program (ODP) and the upcoming Integrated Ocean Drilling Program (IODP). We apply a newly developed light-weight, mobile NMR core scanner as a non-destructive instrument to determine routinely rock porosity and to estimate the pore size distribution. The NMR core scanner is used for transverse relaxation measurements on water-saturated core sections using a CPMG sequence with a short echo time. A regularized Laplace-transform analysis yields the distribution of transverse relaxation times T2. In homogeneous magnetic fields, T2 is proportional to the pore diameter of rocks. Hence, the T2 signal maps the pore-size distribution of the studied rock samples. For fully saturated samples the integral of the distribution curve and the CPMG echo amplitude extrapolated to zero echo time are proportional to porosity. Preliminary results show that the NMR core scanner is a suitable tool to determine rock porosity and to estimate pore size distribution of limestones and sandstones. Presently our investigations focus on Leg 204, where NMR Logging-While-Drilling (LWD) was performed for the first time in ODP. Leg 204 was drilled into Hydrate Ridge on the Cascadia accretionary margin, offshore Oregon. All drilling and logging operations were highly successful, providing excellent core, wireline, and LWD data from adjacent boreholes. Cores recovered during Leg 204 consist mainly of clay and claystone. As the NMR core scanner operates at frequencies higher than that of the well-logging sensor it has a shorter dead time. This advantage makes the NMR core scanner sensitive to signals with T2 values down to 0.1 ms as compared to 3 ms in NMR logging. Hence, we can study even rocks with small pores, such as the mudcores recovered during Leg 204. We present a comparison of data from core scanning and NMR logging. Future integration of conventional wireline data and electrical borehole wall images (RAB/FMS) will provide a detailed characterization of the sediments in terms of lithology, petrophysics and, fluid flow properties.

High-resolution palaeomagnetic records of the Laschamp geomagnetic excursion from the Blake Ridge

NASA Astrophysics Data System (ADS)

Mac Niocaill, C.; Bourne, M. D.; Thomas, A. L.; Henderson, G. M.

2013-05-01

Geomagnetic excursions are brief (1000s of years) deviations in geomagnetic field behaviour from that expected during 'normal secular' variation. The Laschamp excursion (~41 ka) was a global deviation in geomagnetic field behaviour. Previously published records suggest rapid changes in field direction and a concurrent substantial decrease in field intensity. Accurate dating of excursions and determinations of their durations from multiple locations is vital to our understanding to global field behaviour during these deviations. We present here high-resolution palaeomagnetic records of the Laschamp excursion obtained from two Ocean Drilling Program (ODP) Sites 1061 and 1062 on the Blake-Bahama Outer Ridge (ODP Leg 172) Relatively high sedimentation rates (~30-40 cm kyr-1) at these locations allow the determination of transitional field behaviour during the excursion. Despite their advantages, sedimentary records can be limited by the potential for unrecognized variations in sedimentation rates between widely spaced age-constrained boundaries. Rather than assuming a constant sedimentation rate between assigned age tie-points, we employ measurements of the concentration of 230Thxs in the sediment. 230Thxs is a constant flux proxy and may be used to assess variations in the sedimentation rates through the core sections of interest. Following this approach, we present a new age model for Site 1061 that allows us to better determine the temporal behaviour of the Laschamp excursion with greater accuracy and known uncertainty. Palaeomagnetic measurements of discrete samples from four cores reveal a single excursional feature, across an interval of 30 cm, associated with a broader palaeointensity low. The excursion is characterised by rapid transitions (less than 200 years) between a stable normal polarity and a partially-reversed, polarity. Peaks in inclination either side of the directional excursion indicate periods of time when the local field is dominated by vertical flux patches. Similar behaviour has been observed in records of the Iceland Basin Excursion from the same region. The palaeointensity record is in good agreement between the two sites. The palaeointensity record shows two prominent minima, the first associated with the Laschamp excursion at 41 ka and the second at ~34 ka, possibly associated with the elusive 'Mono-Lake' excursion. Similar field intensity behaviour has been observed during the Blake excursion suggesting that the geomagnetic field stability may be reduced for relatively long durations, potentially up to tens of thousands of years. Using the 230Thxs derived sedimentation rate, we determine that the directional excursion at this location was no longer than ~400 years, occurring within a palaeointensity low lasting 2000 years. We compare this record with previously published records of the Blake and Iceland Basin Excursions from nearby locations. The Laschamp excursion at this location appears to be much shorter in duration than the Blake and Iceland Basin excursions.

International Methane Hydrate Research and Development Workshop (6th) held in Bergen, Norway on May 13-15, 2008

DTIC Science & Technology

2009-07-22

Quantification Global Synthesis National and International Collaboration Gulf of Mexico JIP Mallik ODP 204, IODP 311 North Slope, AK India ODP 164...permafrost regions that hydrates are being studied include: • 1. Mallik Wells • 2. Arctic slope to Wainwright Alaska • 3. May be Russian effort in...commercial exploitation from arctic hydrates can be a reality? Are there any incitements for international collaboration beyound Mallik II and other ongoing

Passive, off-axis convection through the southern flank of the Costa Rica rift

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

Fisher, A.T.; Becker, K.; Narasimhan, T.N.

1990-06-10

Pore fluids are passively convecting through young oceanic sediments and crust around Deep Sea Drilling Project (DSDP) site 504 on the southern flank of the Costa Rica Rift, as inferred from a variety of geological, geochemical, and geothermal observations. The presence of a fluid circulation system is supported by new data collected on Ocean Drilling Program (ODP) leg 111 and a predrilling survey cruise over the heavily sedimented, 5.9 Ma site; during the latter, elongated heat flow anomalies were mapped subparallel to structural strike, with individual measurements of twice the regional mean value, and strong lateral and vertical geochemical gradientsmore » were detected in pore waters squeezed from sediment cores. Also, there is a strong correlation between heat flow, bathymetry, sediment thickness, and inferred fluid velocities up through the sediments. Although the forces which drive passive circulation are not well understood, it has generally been thought that the length scale of heat flow variations provides a good indication of the depth of hydrothermal circulation within the oceanic crust. The widely varied geothermal and hydrogeological observations near site 504 are readily explained by a model which combines (1) basement relief, (2) irregular sediment drape, (3) largely conductive heat transfer through the sediments overlying the crust, and (4) thermal and geochemical homogenization of pore fluids at the sediment/basement interface, which results from (5) topographically induced, passive hydrothermal circulation with large aspect ratio, convection cells. This convection involves mainly the permeable, upper 200-300 m of crust; the deeper crust is not involved.« less

Approaches to Linked Open Data at data.oceandrilling.org

NASA Astrophysics Data System (ADS)

Fils, D.

2012-12-01

The data.oceandrilling.org web application applies Linked Open Data (LOD) patterns to expose Deep Sea Drilling Project (DSDP), Ocean Drilling Program (ODP) and Integrated Ocean Drilling Program (IODP) data. Ocean drilling data is represented in a rich range of data formats: high resolution images, file based data sets and sample based data. This richness of data types has been well met by semantic approaches and will be demonstrated. Data has been extracted from CSV, HTML and RDBMS through custom software and existing packages for loading into a SPARQL 1.1 compliant triple store. Practices have been developed to streamline the maintenance of the RDF graphs and properly expose them using LOD approaches like VoID and HTML embedded structured data. Custom and existing vocabularies are used to allow semantic relations between resources. Use of the W3c draft RDF Data Cube Vocabulary and other approaches for encoding time scales, taxonomic fossil data and other graphs will be shown. A software layer written in Google Go mediates the RDF to web pipeline. The approach used is general and can be applied to other similar environments like node.js or Python Twisted. To facilitate communication user interface software libraries such as D3 and packages such as S2S and LodLive have been used. Additionally OpenSearch API's, structured data in HTML and SPARQL endpoints provide various access methods for applications. The data.oceandrilling.org is not viewed as a web site but as an application that communicate with a range of clients. This approach helps guide the development more along software practices than along web site authoring approaches.

Fish Productivity in Open-Ocean Gyre Systems in the Late Oligocene and Miocene

NASA Astrophysics Data System (ADS)

Cuevas, J. M.; Sibert, E. C.; Norris, R. D.

2015-12-01

Understanding how marine ecosystems respond to climate change is very important as we continue to warm the climate. Fish represent a critical protein source for a significant portion of the global population, and as such, an understanding of fish production and its interactions with climate change may help better prepare for the future. Ichthyoliths, fossil fish teeth and shark scales, are a novel fossil group which can be used as an indicator for fish productivity. Several important climate events occurred during the Miocene (7 to 23 Ma), including the Middle Miocene Climatic Optimum. Here we reconstruct fish production from across the Miocene from Pacific and Atlantic Ocean gyres. South Atlantic samples, from Deep Sea Drilling Program (DSDP) Site 522 spanning from 30 to 20 Ma, show fairly variable numbers in the Oligocene (ranging from 100 to 800 ich/cm2/yr), but stabilization in the Early Miocene (around 400 ich/cm2/yr), suggesting that the beginning of the Miocene brought consistent conditions for fish production. In the North Pacific, our record from Ocean Drilling Program (ODP) Site 886 shows a distinct crash in fish productivity at 11 Ma, from 3500 ich/cm2/yr to a steady decline around 100 ich/cm2/yr for the next million years. This crash is followed by a marked increase in the presence of diatoms and biogenous opal. This is somewhat surprising, since in modern oceanic systems, an increase in diatoms and other large-celled phytoplankton is associated with shorter, more efficient food chains and higher levels of fish. It is also interesting to note that denticles remain consistently low at both sites, indicating consistently low shark populations through this time period. Together, these results suggest that the Late Oligocene and Miocene was a time of variable fish production and provide a window into understanding of dynamic ecosystem changes through the Miocene in open-ocean gyre ecosystems.

A Detailed Record of Changing Surface Water Conditions From Sediments Deposited During Marine Isotope Stage 11, ODP Site 980, Northeast Atlantic Ocean

NASA Astrophysics Data System (ADS)

Arvin, T. A.; Cullen, J. L.; Oppo, D. W.; McManus, J. F.

2004-05-01

Many recent paleoceanographic studies have focused on using high sedimentation rate deep-sea sediment sections that have produced records of abrupt climate variability operating at sub-orbital time scales. This is particularly true in the North Atlantic where proxies of changing surface water conditions from high quality sediment records have repeatedly demonstrated that millennial-scale climate change has been the rule rather than the exception over the past 500 kyr, during both glacial and interglacial intervals. Abrupt climate change during warm interglacials is an area of special interest as it may relate more directly to an understanding of recent and future climate change. With this in mind we have focused our efforts on documenting millennial-scale climate change from sediments deposited at ODP Site 980, northeast Atlantic Ocean during Marine Isotope Stage (MIS) 11. We have used unsplit, whole sample >150 micron size fractions from over 200 sediment samples to record changes in the number lithic grains per gram sediment to measure changes in the input of Ice-Rafted Debris (IRD). We then compare our new IRD record to previously generated records of changing surface water conditions during MIS11: variations in oxygen isotopic composition of the surface dwelling planktic foraminifer species N. pachyderma, right coiling and changes in the relative abundance of the polar species N. pachyderma, left coiling. Our MIS11 results are then compared to compatible records from MIS5e and the Holocene. Our detailed IRD record from around 418 kya to 382 kya reveals a remarkable lack of even trace amounts IRD input into sediments at ODP Site 980. IRD concentration abruptly drops and remains 0 to trace amounts per gram as soon as benthic delta O-18 values fall to and remain at < 3.5 per mil at the onset of MIS11. Only three very small amplitude IRD events are observed over the entire 35 kyr interval. The earliest 8 kyr of MIS11 is completely devoid of any IRD, despite the fact that the relative abundance of the polar species N. pachyderma, left coiling, after dropping from near 90% to below 10% at 418 kya, rises to as high as 30% during this early MIS11 time interval. This seems to indicate the influx of non-ice bearing colder polar waters to the region above Site 980 that don't seem to be influencing he N. pachyderma, right coiling isotope record in a simple way. The MIS11 IRD record significantly differs from our records from MIS5e and the Holocene, particularly when we focus on the earliest 12 kyr of MIS11. Both the approximately 10 kyr long MIS5e interval and the last 11 kyr of the Holocene exhibit a series of between 6 and 9 discrete small amplitude increases in IRD against a background of little or no IRD. At the same time relative abundances of N. pachyderma, left coiling are considerably less during both MIS5e and the Holocene when compared to the first 10 kyr of MIS11. The evidence presented here suggests that MIS11 surface water conditions above Site 980 were somewhat different from conditions recorded in sediments from two other warm interglacial intervals, MIS5e and the Holocene and that its use as an ancient analog to modern and future climate may be less straightforward than previously thought.

What is an Oceanic Core Complex?

NASA Astrophysics Data System (ADS)

Schroeder, T.; Cheadle, M. J.

2007-12-01

The Mid-Atlantic Ridge (MAR) 75km north and south of the 15-20 Fracture Zone (FZ) has produced upper oceanic lithosphere composed dominantly of mantle peridotite with gabbro intrusions. In the absence of diapirism, mantle peridotite can only be exposed on the seafloor by extensional faulting, thus the sea floor geology and bathymetry provide widespread evidence for extensive low-angle faulting. However, only 3% of the seafloor in this region has the domal morphology characteristic of features that have been termed oceanic core complexes; suggesting that other processes, in addition to low-angle faulting, are responsible for the generation of domal core complexes. Most low-angle faults near the 15-20 FZ form gently dipping (10-15°), 10-15km-wide dip slopes on the flanks of 2000m relief bathymetric ridges that are up to 15-40km long (parallel to the MAR). Core recovered from ODP Leg 209 drill holes in these ridges is dominantly peridotite with small (<50m thick) gabbro intrusions. The peridotite is cut by a very high density of brittle faults dipping at both steep and gentle angles. Several holes also contain long-lived shear zones/faults in their upper reaches in which strain was localized at granulite facies, indicated by mylonitic olivine and cpx, and remained active during cooling to sub-greenschist grade, indicated by cross-cutting of progressively lower-grade syn-deformation mineral assemblages. These observations suggest that seafloor spreading is largely accommodated here by slip on low-angle faults, and that these faults are correctly termed detachment faults. Holes drilled into a domal oceanic core complex north of the 15-20 FZ during Leg 209 (ODP Site 1275) recovered dominantly gabbro and not mantle peridotite. This hole is cut by significantly fewer brittle and ductile faults than the peridotite drilled at the non-core-complex detachment fault sites. The detachment fault in the upper reaches (50m) of Site 1275 was localized at temperatures near feldspar's ductile-to-brittle transition, indicated by cataclasis with minor crystal plastic flow in plagioclase, and a lack of pervasive pure-ductile deformation. Amphibole-plagioclase thermometry in the fault yields equilibrium temperatures from 600-650°C, compared to equilibrium temperatures of 750-850°C for the gabbro outside the fault. The presence of talc- chlorite schists and cataclasites cutting the higher-temperature deformation textures indicate fault activity down- temperature from amphibolite through greenschist facies. This core-complex-bounding fault contrasts with the fault that bounds the Atlantis Bank Core Complex on the Southwest Indian Ridge (SWIR). There, the fault is 100m thick and strain was initially localized at granulite grade (>800°C) (Mehl & Hirth, 2007); significantly hotter than the Site 1275 fault. Therefore, the formation of core-complex morphology does not seem to depend on the initial faulting conditions. Both oceanic core complexes that have been drilled besides Site 1275, Atlantis Massif at 30°N (IODP Hole 1309D) on the MAR and Atlantis Bank on the SWIR (ODP Hole 735B), are also comprised dominantly of gabbro. This suggests that magma supply may be an essential requirement for core complex formation and raises the question whether all domal oceanic core complexes are cored by gabbro? We also ask whether the term 'oceanic core complex' should be restricted to these domal features and not applied to detachment-bound, non- domal, peridotite-cored ridges; or if these should be considered two sub-classes of oceanic core complexes.

Are the binary typology models of alcoholism valid in polydrug abusers?

PubMed

Pombo, Samuel; da Costa, Nuno F; Figueira, Maria L

2015-01-01

To evaluate the dichotomy of type I/II and type A/B alcoholism typologies in opiate-dependent patients with a comorbid alcohol dependence problem (ODP-AP). The validity assessment process comprised the information regarding the history of alcohol use (internal validity), cognitive-behavioral variables regarding substance use (external validity), and indicators of treatment during 6-month follow-up (predictive validity). ODP-AP subjects classified as type II/B presented an early and much more severe drinking problem and a worse clinical prognosis when considering opiate treatment variables as compared with ODP-AP subjects defined as type I/A. Furthermore, type II/B patients endorse more general positive beliefs and expectancies related to the effect of alcohol and tend to drink heavily across several intra- and interpersonal situations as compared with type I/A patients. These findings confirm two different forms of alcohol dependence, recognized as a low-severity/vulnerability subgroup and a high-severity/vulnerability subgroup, in an opiate-dependent population with a lifetime diagnosis of alcohol dependence.

Atmospheric lifetimes and ozone depletion potentials of methyl bromide (CH3Br) and dibromomethane (CH2Br2)

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

Mellouki, A.; Talukdar, R.K.; Schmoltner, A.

The rate coefficients for the reactions of OH radical with CH3Br and CH2Br2 were measured as functions of temperature using the laser photolysis - laser induced fluorescence method. This data was incorporated into a semiempirical model (Solomon et al., 1992) and a 2D model to calculate the steady-state ozone depletion potentials (ODP) and atmospheri lifetimes, tau, with greatly improved accuracy as compared to earlier studies. The calculated ODPs and tau are 0.65 and 1.7 years and 0.17 and 0.41 years for CH3Br and CH2Br2, respectively, using the semiempirical model. These lifetimes agree well with those calculated using a 2D model.more » This study better quantifies the ODPs and tau of these species which are needed inputs for discussion of possible regulation of human emissions currently under international considerations. 29 refs.« less

Are chlorine-free compounds a solution for health problems caused by ozone-depleting substances?

PubMed

Valić, F; Beritić-Stahuljak, D

1996-01-01

In January 1996, the Government of Croatia and United Nations Environment Programme (UNEP) signed an agreement on the phasing out of ozone-depleting substances in Croatia, making the problem of identifying adequate substitutes a high priority. In this paper, the main ecologic characteristics of chlorine-containing fully halogenated chlorofluorocarbons (CFCs) and partially halogenated chlorofluorocarbons (HCFCs) compared with chlorine-free hydrofluorocarbons (HFCs) are presented. The data showed HCFCs to be ecologically more acceptable than CFCs, particularly regarding the ozone-depleting potential (ODP), and have therefore been proposed as substitutes for CFCs. However, although having lower ODP, long-term they could still harm the stratospheric ozone layer, and are therefore hardly acceptable. HFCs are promising substitutes which, having no chlorine, have no ODP. Six were toxicologically evaluated; three of them were found flammable. Toxicological characteristics of three nonflammable compounds (HFC 125, HFC 134a and HFC 227ea) are presented. Their toxicity, not yet completely evaluated, appears to be low.

On-and offshore tephrostratigraphy and -chronology of the southern Central American Volcanic Arc (CAVA)

NASA Astrophysics Data System (ADS)

Schindlbeck, J. C.; Kutterolf, S.; Hemming, S. R.; Wang, K. L.

2015-12-01

Including the recently drilled CRISP sites (IODP Exp. 334&344) the deep sea drilling programs have produced 69 drill holes at 29 Sites during 9 Legs at the Central American convergent margin, where the Cocos plate subducts beneath the Caribbean plate. The CAVA produced numerous plinian eruptions in the past. Although abundant in the marine sediments, information and data regarding large late Cenozoic explosive eruptions from Costa Rica, Nicaragua, Honduras, El Salvador, and Guatemala remain very sparse and discontinuous on land. We have established a tephrostratigraphy from recent through Miocene times from the unique archive of ODP/IODP sites offshore Central America in which we identify tephra source regions by geochemical fingerprinting using major and trace element glass shard compositions. Here we present first order correlations of ­~500 tephra layers between multiple holes at a single site as well as between multiple sites. We identified ashes supporting Costa Rican (~130), Nicaraguan (17) and Guatemalan (27) sources as well as ~150 tephra layers from the Galápagos hotspot. Within our marine record we also identified well-known marker beds such as the Los Chocoyos tephra from Atitlán Caldera in Guatemala and the Tiribi Tuff from Costa Rica but also correlations to 15 distinct deposits from known Costa Rican and Nicaraguan eruptions within the last 4.1 Ma. These correlations, together with new radiometric age dates, provide the base for an improved tephrochronostratigraphy in this region. Finally, the new marine record of explosive volcanism offshore southern CAVA provides insights into the eruptive history of long-living volcanic complexes (e.g., Barva, Costa Rica) and into the distribution and frequency of large explosive eruptions from the Galápagos hotspot. The integrated approach of Ar/Ar age dating, correlations with on land deposits from CAVA, biostratigraphic ages and sediment accumulation rates improved the age models for the drilling sites.

Global change across the Oligocene-Miocene transition: High-resolution stable isotope records from IODP Site U1334 (equatorial Pacific Ocean)

NASA Astrophysics Data System (ADS)

Beddow, Helen M.; Liebrand, Diederik; Sluijs, Appy; Wade, Bridget S.; Lourens, Lucas J.

2016-01-01

The Oligocene-Miocene transition (OMT) (~23 Ma) is interpreted as a transient global cooling event, associated with a large-scale Antarctic ice sheet expansion. Here we present a 2.23 Myr long high-resolution (~3 kyr) benthic foraminiferal oxygen and carbon isotope (δ18O and δ13C) record from Integrated Ocean Drilling Program Site U1334 (eastern equatorial Pacific Ocean), covering the interval from 21.91 to 24.14 Ma. To date, five other high-resolution benthic foraminiferal stable isotope stratigraphies across this time interval have been published, showing a ~1‰ increase in benthic foraminiferal δ18O across the OMT. However, these records are still few and spatially limited and no clear understanding exists of the global versus local imprints. We show that trends and the amplitudes of change are similar at Site U1334 as in other high-resolution stable isotope records, suggesting that these represent global deep water signals. We create a benthic foraminiferal stable isotope stack across the OMT by combining Site U1334 with records from ODP Sites 926, 929, 1090, 1264, and 1218 to best approximate the global signal. We find that isotopic gradients between sites indicate interbasinal and intrabasinal variabilities in deep water masses and, in particular, note an offset between the equatorial Atlantic and the equatorial Pacific, suggesting that a distinct temperature gradient was present during the OMT between these deep water masses at low latitudes. A convergence in the δ18O values between infaunal and epifaunal species occurs between 22.8 and 23.2 Ma, associated with the maximum δ18O excursion at the OMT, suggesting climatic changes associated with the OMT had an effect on interspecies offsets of benthic foraminifera. Our data indicate a maximum glacioeustatic sea level change of ~50 m across the OMT.

East Antarctic ice-sheet dynamics between 5.2 and 0 Ma from a high-resolution terrigenous particle size record, ODP Site 1165, Prydz Bay-Cooperation Sea

USGS Publications Warehouse

Passchier, S.

2007-01-01

This paper discusses a 5.2-0 Ma high-resolution terrigenous particle size record recovered from a sediment drift off East Antarctica. The particle size properties of Hole 1165B are interpreted in the context of previously acquired data on a continental shelf to slope transect drilled by ODP Leg 188 in Prydz Bay and the Cooperation Sea. The new data indicate that the Lambert ice stream stayed predominantly landward of the shelf break in the early Pliocene (5.2-3.5 Ma) with periods of ice sheet recession on land. The middle Pliocene (3.5-3.1 Ma) is characterized as major ice expansion during glacials with deposition of laminated clays from meltwater plumes on the continental rise, alternating with periods of ice recession. A change in sedimentary facies and a decrease in sedimentation rates occurred at ~3.1 Ma indicating a more retreated Lambert Glacier. Between 2.5 and 1 Ma the ice stream was generally stable and had become cold-based with ice flow in a glacial trough extending to the shelf break. Three-four large pulses of coarse-grained glacigenic debris mark the record at ~1 Ma. These are interpreted as extensive calving due to decoupling of the marine terminus from its bed in response to Northern Hemisphere deglaciations and associated sea level rises.

First Toba supereruption revival

NASA Astrophysics Data System (ADS)

Lee, Meng-Yang; Chen, Chang-Hwa; Wei, Kuo-Yen; Iizuka, Yoshiyuki; Carey, Steven

2004-01-01

Little has been known about the earliest Toba eruptive episodes that created the largest-known caldera complex of Quaternary age. Here we report evidence for the eastward dispersal of the oldest Toba tuff in South China Sea sediments to 2500 km away from the source. The tephra deposits occur below the Brunhes-Matuyama geomagnetic boundary (778 ka) and slightly above the Australasian microtektite layer (793 ka). Calibrated by astronomically tuned oxygen isotope stratigraphy, the middle Pleistocene Toba eruption occurred during the deglaciation at 788 ± 2.2 ka, according to the tephra occurrence between marine isotope stages 20 and 19. This refined age is in good agreement with the 40Ar/39Ar date of 800 ± 20 ka for the Toba tephra (layer D) from Ocean Drilling Program (ODP) Site 758, but significantly younger than the commonly cited Ar/Ar age of 840 ± 30 ka. The eruption expelled at least 800 1000 km3 dense-rock-equivalent of rhyolitic magma on the basis of the widespread tephra-fall deposit in the basins of the Indian Ocean and the South China Sea. In spite of its exceptional magnitude, the timing of this major eruption does not indicate a causal linkage between this event and a long-term global climatic deterioration.

Fore-arc mantle peridotites and back-arc basin basalts from the Izu-Bonin-Mariana subduction factory (ODP LEGs 125 and 195): a modern analogue for Mediterranean ophiolites

NASA Astrophysics Data System (ADS)

Zanetti, A.; D'Antonio, M.; Vannucci, R.; Raffone, N.; Spadea, P.

2009-04-01

Serpentinites, basaltic lavas and calc-alkaline volcanoclastic sequences sampled during recent Ocean Drilling Program cruises in the western Pacific Ocean allow comparisons with ophiolites from eastern Mediterranean area, which are believed to be related to marginal seas characterised by rapidly propagating back-arc extension and slab rollback (e.g. Albania and Cyprus). Serpentinites recovered at the Torishima, Conical and South Chamorro Seamounts (ODP Legs 125 and 195), located on the Izu-Bonin-Mariana (IBM) forearc, still record complex petrochemical features acquired during their high-T mantle evolution. This latter has been referred to a three-stages-model, involving in chronological sequence: 1) adiabatic mantle upwelling accompanied by 20-25% polybaric partial melting; 2) local depletion in modal orthopyroxene determined by reactive melt migration; 3) late interstitial crystallisation of ultra-depleted to depleted melts. The record of the first stage is preserved in the less-refractory IBM forearc peridotites, which compositions lie on trends describing the decompression melting of uprising asthenospheric mantle. During this stage, the peridotites were actual melt sources. The large average degree of depletion suggests that partial melting events were assisted by particularly hot geotherms. The second stage occurred at relatively lower pressures, according to the large orthopyroxene dissolution, and is guessed to be firmly related to arc volcanism. Nevertheless, the progressive change of oxidation state of the mantle minerals, which decreases from the Torishima (N Izu-Bonin forearc) through the Conical (N Mariana forearc) to the South Chamorro Seamount (S Mariana forearc), highlights a marked gradient in terms of contribution to the uprising melts from slab-derived component. It is argued that the melt compositions changed from boninitic (at Torishima) to depleted-MORB at (South Chamorro). The third stage determined the petrographic and mineralogical features occurring in all IBM forearc peridotites (e.g. crystallisation of late cpx, embayment of opx porphyroclasts), and likely marks the accretion of the mantle sequence to the thermal boundary layer. It was accompanied by the devolopment of transient geochemical gradients in the migrating liquids mainly governed by chromatographic-type chemical exchange with the peridotite. The West Philippine Basin (WPB) is a back-arc basin that opened in the Philippine Sea Plate (PSP) between the current position of the Palau-Kyushu Ridge (PKR) and the margin of East Asia. Spreading occurred at the Central Basin Fault (CBF) from 54 to 30 Ma. The PKR was active since ~48 to 35 Ma constituting a single volcanic arc with the Izu-Bonin-Mariana Arc. ODP Leg 195 Site 1201 is located in the WPB, ~100 km west of the PKR, on 49 Ma basaltic crust formed by NE-SW spreading at the CBF. From ~35 to 30 Ma, pelagic sedimentation at Site 1201 was followed by turbidite sedimentation, fed mostly by early Mariana Arc (PKR)-derived volcanic clasts. These volcanics are calc-alkaline, whereas PKR rocks from literature have mostly boninitic and arc tholeiitic affinity; the WPB basement basalts have MORB to arc-like affinity, as expected for a back-arc basin. Sr, Nd, Pb and Hf isotope data highlight the Indian Ocean MORB-like character of WPB basement basalts, suggesting an upper mantle domain distinct from that underlying the Pacific Plate. The geochemical and isotopic features of PKR volcanics reflect higher amounts of subduction-derived components, added mostly as siliceous melts, in the source of arc magmas relative to that of basement basalts. In that respect, Site 1201 PKR volcanics resemble calc-alkaline volcanics of the currently active Mariana Arc. In addition, their calc-alkaline affinity, unradiogenic neodymium, and inferred Middle Oligocene age, suggest they might represent an evolved stage of arc volcanism at Palau-Kyushu Ridge, perhaps shortly before the end of its activity.

Analysis of DGGE profiles to explore the relationship between prokaryotic community composition and biogeochemical processes in deep subseafloor sediments from the Peru Margin.

PubMed

Fry, John C; Webster, Gordon; Cragg, Barry A; Weightman, Andrew J; Parkes, R John

2006-10-01

The aim of this work was to relate depth profiles of prokaryotic community composition with geochemical processes in the deep subseafloor biosphere at two shallow-water sites on the Peru Margin in the Pacific Ocean (ODP Leg 201, sites 1228 and 1229). Principal component analysis of denaturing gradient gel electrophoresis banding patterns of deep-sediment Bacteria, Archaea, Euryarchaeota and the novel candidate division JS1, followed by multiple regression, showed strong relationships with prokaryotic activity and geochemistry (R(2)=55-100%). Further correlation analysis, at one site, between the principal components from the community composition profiles for Bacteria and 12 other variables quantitatively confirmed their relationship with activity and geochemistry, which had previously only been implied. Comparison with previously published cell counts enumerated by fluorescent in situ hybridization with rRNA-targeted probes confirmed that these denaturing gradient gel electrophoresis profiles described an active prokaryotic community.

Induced and catalysed mineral precipitation in the deep biosphere

NASA Astrophysics Data System (ADS)

Meister, Patrick

2017-04-01

Authigenic and early diagenetic minerals provide archives of past (bio)geochemical processes. In particular, isotopic signatures preserved in the diagenetic phases have been shown to document drastic changes of subsurface microbial activity (the deep biosphere) over geological time periods (Contreras et al., 2013; Meister, 2015). Geochemical and isotopic signatures in authigenic minerals may also document surface conditions and past climate. Nevertheless, such use of authigenic mineral phases as (bio)geochemical archives is often hampered by the insufficient understanding of mineral precipitation mechanisms. Accordingly the time, place and rate of mineral precipitation are often not well constrained. Also, element partitioning and isotopic fractionation may be modified as a result of the precipitation mechanism. Early diagenetic dolomite and quartz from drilled sequences in the Pacific were compared with adjacent porewater compositions and isotope signatures to gain fundamental insight into the factors controlling mineral precipitation. The formation of dolomite in carbonate-free organic carbon-rich ocean margin sediments (e.g. Peru Margin; Ocean Drilling Program, ODP, Site 1229; Meister et al., 2007) relies on the alkalinity-increase driven by anaerobic oxidation of methane and, perhaps, by alteration of clay minerals. In contrast, quartz is often significantly oversaturated in marine porewaters as the dissolved silica concentration is buffered by more soluble opal-A. For example, quartz does not form throughout a 400 metre thick sedimentary sequence in the Eastern Equatorial Pacific (ODP Site 1226; Meister et al., 2014) because it is kinetically inhibited. This behaviour can be explained by Ostwald's step rule, which suggests that the metastable phase forms faster. However, hard-lithified quartz readily forms where silica concentration drops sharply below opal-saturation. This violation of Ostwald's step rule must be driven by an auxiliary process, such as the adsorption of silica to freshly precipitated iron oxides along a deep iron oxidation front. In conclusion, two different modes of precipitation can be observed in modern sub-seafloor porewater systems. Dolomite precipitation is thermodynamically controlled through microbially induced supersaturation. Quartz formation is controlled through an auxiliary process that helps it to overcome a kinetic barrier. These observations exemplify the importance to distinguish between kinetic and thermodynamic effects on mineral formation under Earth surface conditions. To evaluate geochemical signatures, these modes of precipitation need to be taken into account. Contreras et al. (2013) Proc. Natl. Acad. Sci., doi/10.1073/pnas.1305981110 Meister, et al. (2007) Sedimentology 54, 1007-1032. Meister, et al. (2014) Geochim. Cosmochim. Acta 137, 188-207. Meister, P. (2015) Terra Nova, Focus Article, 00, 1-9.

Long-Term ENSO Variation Over the Last 20,000 Years From the Peru Continental Margin

NASA Astrophysics Data System (ADS)

Skilbeck, G.; Fink, D.; Gagan, M.; Rein, B.

2006-12-01

Three ODP Leg 201 cores from the Peru continental margin comprise highly laminated diatomaceous ooze spanning Last Glacial Maximum to present. Geochemical proxy data, layer counting and spectral analysis of red color variation suggest the layers represent interannual accumulation under the influence tropical ENSO conditions, with darker layers representing El Niño events. AMS 14-C dating (Skilbeck &Fink, 2006) of bulk sediment from Sites 201-1228 and -1229 (~11°S) and comparison with Rein et al. (2005) Core SO147-106KL (~12°S) show that where the shelf is narrow south of ~10.5°S, regionally consistent rates of sediment accumulation have occurred over the late Deglaciation and Holocene, with high rates characterising the late (0-2.0 kyrBP, ~100 cm/ka) and the early (8.5-10 kyrBP, ~80 cm/ka) Holocene. Over these intervals laminae are of interannual resolution. Further north where the shelf is broader, Holocene-Late Deglaciation sediments are thin or absent, but the Early Deglaciation is well represented. In a core from ODP Site 201-1227 (~9°S, 427m water depth), the period 15.5-17.5 kyrBP is characterised by sediment accumulation rates in excess of 300 cm/ka, and interannual laminations are again present. Spectral analysis of the instrumental record of ENSO, the SOI, shows a relative stable mode of variation with an average frequency of about 5.5 yr for the past 130 years. Analysis of our ODP cores shows that the ENSO mode appears to be relatively stable for periods of 300-500 years throughout the Holocene with frequencies varying mostly between 5 and 8 years and relatively sudden mode switches, suggesting inter alia that the instrumental record is not long enough to test predictive models of ENSO variation. Throughout the Holocene, this pattern of variation transcends the sedimentation-rate zones identified above, with the inference that changes in the rate of sedimentation have not influenced the temporal pattern. The later part of the deglaciation period (10-14 kyrBP) appears to be a relatively long period of stable ENSO with a repeat frequency between 5 and 6 years. Layer variation over the interval between 14 to 15.5 yrBP loses interannual variability and is characterised by a dominant frequency of ~11-12 yr, but this may simply reflect the low sedimentation rate during this interval. During Early Deglaciation interannual- to decadal-scale layer variability is present, with over 600 discernable laminae recognisable across the ~1600 year interval represented in Core 210-1227B. ENSO during this time has multiple interannual frequency modes ranging between 4 and 10 yr, particularly over the interval 17.2- 16.2 kyrBP, with mode switches slightly more frequent than during the Holocene at between 200 and 300 years. In addition to the interannual laminations and the centennial-scale pattern of frequency mode variation described above, there is a regular oscillatory pattern in the contrast between dark and light laminations which can be traced to parasequence-like packets of laminations on a centimetre scale, and representing variability in the decadal to centennial range. References Rein, B., A. Luckge, et al. (2005). Paleoceanography 20(PA4003): 17p. Skilbeck, C.G. &D. Fink (2005). ODP Scientific Results 201.

Paleomagnetic Results From the Pleistocene Sediments of Lomonosov Ridge, Central Artic Ocean, IODP Leg 302

NASA Astrophysics Data System (ADS)

King, J. W.; Heil, C.; O'Regan, M.; Moran, K.; Gattacecca, J.; Backman, J.; Jakobsson, M.; Moore, T.

2005-12-01

Two major conclusions can be drawn from magnetic studies of Pleistocene sediments drilled on Lomonosov Ridge, central Arctic Ocean during IODP Leg 302. The first conclusion is that central Arctic Ocean sedimentation rates approach 2 cm/ka during the Pleistocene, thereby resolving the Arctic sedimentation rate controversy in favor of "fast" rates. The second conclusion is that abundant broad intervals of reversed polarity during the Pleistocene are a consistent characteristic of Arctic sedimentary records. These broad reversed intervals have helped perpetuate the Arctic sedimentation rate controversy. The weight of evidence strongly indicates that these reversal intervals are excursions. They do not occur during the late Brunhes Epoch (approximately 0-250,000 BP), but occur during the mid to lower Brunhes Epoch and persist into the upper Matuyama Epoch. We observe a strong correlation between rock magnetic variations, color changes, and physical property stratigraphy and these excursions. The model for Arctic sedimentation indicates that the excursions primarily occur during "interglacial" intervals. Previous high quality paleomagnetic studies of Bermuda Rise sediments have shown that approximately 85 % of Brunhes age excursions occur during interglacial periods (Lund, et al., 2001). In addition, similar excursions do not appear to occur at high southern latitudes (e.g. Acton, et al., 2002). For these reasons, we feel that hypotheses that attribute the interesting observed Arctic paleomagnetic behavior to environmental controls (e.g. sedimentation processes) are favored over those involving geomagnetic field behavior within the tangent cylinder. Acton, G. D., Guyodo, Y., and S. A. Brachfeld, 2002. Magnetostratigraphy of sediment drifts on the continental rise of West Antarctica (ODP Leg 178, Sites 1095, 1096, and 1101). In Barker, P. F., Camerlenghi, A., Acton, G. D., and Ramsay, A.T.S (Eds.), Proc. ODP Sci. Results, v. 178; 1-61 (CD ROM). Lund, S. P., G. D. Acton, B. Clement, M. Okada, and T. Williams. 2001. Brunhes chron magnetics excursions recovered from Leg 172 sediments. In Keigwin, L. D., Rio, D., Acton, G. D., and Arnold, E., (eds.) Proc. ODP Sci. Results, v. 172; p. 1-18 (Online)

Tropical sea surface temperature variability near the Oligocene - Miocene boundary

NASA Astrophysics Data System (ADS)

Zhang, Y.; Pagani, M.

2010-12-01

The Oligocene/Miocene (O-M) boundary is characterized by a period of rapid and intense glaciation labeled Mi-1 at ~ 23.1 Ma. An abrupt 1.5‰ increase in the benthic foraminifera oxygen isotope composition that characterizes Mi-1 may indicate a (1) significant deep-water temperature decrease; (2) major ice-sheet expansion, or the combination of both. Current coarse Mg/Ca-based temperature estimations for the early Miocene suggests that deep-ocean temperatures were ~2°C warmer than Today [1, 2]. However, Mg/Ca based temperatures can also be influenced by changes in the carbonate ion concentration, vital effects, and diagenesis. In particular, recent evidence from mid-ocean ridge flank carbonate veins shows dramatic seawater Mg/Ca ratio changes during the Neogene (Mg/Ca from ~2.2 to 5.3, [3]), which further challenges the application of Mg/Ca thermometry. Owing to poor temperature constraints, current ice volume estimations for the late Oligocene/early Miocene range from 125% of the present-day East Antarctic Ice Sheet (EAIS) to a nearly complete collapse of the Antarctic glaciers [4]. Here we present tropical sea surface temperatures (SSTs) records based on TEX86 and alkenone UK37 near the O-M boundary. Sediment samples from Ocean Drilling Program (ODP) Site 926 in the Ceara Rise (tropical Atlantic) and Site 1148 in the South China Sea (tropical Pacific) were subject to lipid extraction, separation, gas chromatography, and liquid chromatography-mass spectrometry analysis. TEX86-based SST indicates that the tropics were ~3-4°C warmer than today and relatively stable during Mi-1. This suggests that ice-sheet dynamics, rather than temperature, might be responsible for the observed oxygen isotope changes during the O-M boundary. Further, O-M boundary averaged temperatures recorded at site 926 is ~ 0.5°C higher relative to the late Eocene from site 925 (a nearby site [5]). Given late Oligocene benthic δ18O that suggests at least 1‰ enrichment relative to the late Eocene (e.g. ODP 1218 [2]), our records suggest major Antarctic ice build-up in the Oligocene. Additional work across high-latitude sites is necessary to evaluate how the extratropics responded to climate change during Mi-1, as well as modeling efforts to quantitatively resolve ice volume from temperature. [1] K. Billups, D.P. Schrag, Paleotemperatures and ice volume of the past 27 Myr revisited with paired Mg/Ca and 18O/16O measurements on bethic foraminifera, Paleoceanography 17(2002). [2] C.H. Lear, Y. Rosenthal, H.K. Coxall, P.A. Wilson, Late Eocene to early Miocene ice sheet dynamics and the global carbon cycle, Paleoceanography 19(2004). [3] R.M. Coggon, D.A.H. Teagle, C.E. Smith-Duque, J.C. Alt, M.J. Copper, Reconstructing past seawater Mg/Ca and Sr/Ca from Mid-Ocean Ridge flank calcium carbonate veins, Science 327(2010) 1141-1147. [4] S.F. Pekar, R.M. DeConto, High-resolution ice-volume estimates for the early Miocene: Evidence for a dynamic ice sheet in Antarctica, Palaeogeogr. Palaeoclimatol. Palaeoecol. 231(2006) 101-109. [5] Z. Liu, M. Pagani, D. Zinniker, R. DeConto, M. Huber, H. Brinkhuis, S.R. Shah, R.M. Leckie, A. Pearson, Global Cooling During the Eocene-Oligocene Climate Transition, Science 323(2009) 1187-1190.

How synchronous are neogene marine plankton events?

NASA Astrophysics Data System (ADS)

Spencer-Cervato, Cinzia; Thierstein, Hans R.; Lazarus, David B.; Beckmann, Jean-Pierre

1994-10-01

An electronic supplement of this material may be obtained on adiskette or Anonymous FTP from KOSMOS.AGU.ORG. (LOGIN toAGU's FTP account using ANONYMOUS as the username andGUEST as the password. Go to the right directory by typing CDAPEND. Type LS to see what files are available. Type GET and thename of the file to get it. Finally, type EXIT to leave the system.)(Paper 94PA01456, How synchronous are Neogene marine planktonevents?, by C. Spencer-Cervato, H. R. Thierstein, D. B. Lazarus, andJ-P Beckmann). Diskette may be ordered from American GeophysicalUnion, 2000 Florida Avenue, N.W., Washington, DC 20009; $15.00.Payment must accompany order.We analyzed the synchrony and diachrony of commonly used Neogene biostratigraphic events from data published in the Initial Reports of the Deep Sea Drilling Project (DSDP) and in the Proceedings of the Ocean Drilling Program (ODP). On the basis of the combined biostratigraphic and magnetostratigraphic evidence, new Neogene age models were constructed for 35 globally distributed DSDP and ODP holes. Biostratigraphic events from the four major plankton groups (calcareous nannofossils, diatoms, planktonic foraminifera, and radiolarians) were compiled from DSDP and ODP reports. After the elimination of possible sources of error such as stratigraphic hiatuses and reworking of specimens, 124 biostratigraphic events that occurred in at least four holes were analyzed in detail: for each event a biochronologic age estimate was derived by projection of the depth of the event onto the line of correlation of each hole, and from these a global mean age for each event was calculated, together with its standard deviation. Average standard deviations for event ages by fossil group are: calcareous nannofossil first appearance datums (FADs): 0.57 m.y. (21 events), calcareous nannofossil last appearance datums (LADs): 0.60 m.y. (25 events), diatom FADs: 0.57 m.y. (7 events), diatom LADs: 0.85 m.y. (14 events), planktonic foraminifera FADs: 0.88 m.y. (22 events), foraminifera LADs: 0.68 m.y. (16 events), radiolarian FADs: 0.30 m.y. (9 events), radiolarian LADs: 0.31 m.y. (10 events). Since the average sample spacing in the sites used for this analysis is only 0.185 m.y., we have examined the data for true patterns of diachrony and for other biases. Diachrony is more frequent among cosmopolitan than among endemic taxa, thus there is a general trade-off between the obtainable age precision and the geographic extent of a bioevent. Precision of age calibrations also decreases with increasing age. Although some of these features may be due to investigator bias, they appear in part to be real phenomena, and thus could also provide opportunities for further exploration of important paleobiological processes, such as change in environmental gradients through time, evolutionary adaptation of species populations and migration due to water mass changes.

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.

An Evaluation of C1-C3 Hydrochlorofluorocarbon (HCFC) Metrics: Lifetimes, Ozone Depletion Potentials, Radiative Efficiencies, Global Warming and Global Temperature Potentials

NASA Astrophysics Data System (ADS)

Burkholder, J. B.; Papanastasiou, D. K.; Marshall, P.

2017-12-01

Hydrochlorofluorocarbons (HCFCs) have been used as chlorofluorocarbon (CFC) substitutes in a number of applications, e.g. refrigerator and air-conditioning systems. Although HCFCs have lower ozone-depletion potentials (ODPs) compared to CFCs, they are potent greenhouse gases. The twenty-eighth meeting of the parties to the Montreal Protocol on Substances that Deplete the Ozone Layer (Kigali, 2016) included a list of 274 HCFCs to be controlled under the Montreal Protocol. However, from this list, only 15 of the HCFCs have values for their atmospheric lifetime, ODP, global warming potential (GWP), and global temperature potential (GTP) that are based on fundamental experimental studies, while 48 are registered compounds. In this work, we present a comprehensive evaluation of the atmospheric lifetimes, ODPs, radiative efficiencies (REs), GWPs, and GTPs for all 274 HCFCs to be included in the Montreal Protocol. Atmospheric lifetimes were estimated based on HCFC reactivity with OH radicals and O(1D), as well as their removal by UV photolysis using structure activity relationships and reactivity trends. ODP values are based on the semi-empirical approach described in the WMO/UNEP ozone assessment. Radiative efficiencies were estimated, based on infrared spectra calculated using theoretical electronic structure methods (Gaussian 09). GWPs and GTPs were calculated relative to CO2 using our estimated atmospheric lifetimes and REs. The details of the methodology will be discussed as well as the associated uncertainties. This study has provided a consistent set of atmospheric metrics for a wide range of HCFCs that support future policy decisions. More accurate metrics for a specific HCFC, if desired, would require fundamental laboratory studies to better define the OH reactivity and infrared absorption spectrum of the compound of interest. Overall, HCFCs within the same family (isomers) show a large ODP, GWP, GTP dependence on the molecular geometry of the isomers. The atmospheric lifetime of HCFCs is predominantly determined by reaction with the OH radical, with photolysis making only a minor contribution for long-lived highly chlorinated compounds. RE values are within the 0.05 and 0.3 W m-2 ppb-1 range with highly fluorinated HCFCs having the largest RE values.

Ridge 2000 Data Management System

NASA Astrophysics Data System (ADS)

Goodwillie, A. M.; Carbotte, S. M.; Arko, R. A.; Haxby, W. F.; Ryan, W. B.; Chayes, D. N.; Lehnert, K. A.; Shank, T. M.

2005-12-01

Hosted at Lamont by the marine geoscience Data Management group, mgDMS, the NSF-funded Ridge 2000 electronic database, http://www.marine-geo.org/ridge2000/, is a key component of the Ridge 2000 multi-disciplinary program. The database covers each of the three Ridge 2000 Integrated Study Sites: Endeavour Segment, Lau Basin, and 8-11N Segment. It promotes the sharing of information to the broader community, facilitates integration of the suite of information collected at each study site, and enables comparisons between sites. The Ridge 2000 data system provides easy web access to a relational database that is built around a catalogue of cruise metadata. Any web browser can be used to perform a versatile text-based search which returns basic cruise and submersible dive information, sample and data inventories, navigation, and other relevant metadata such as shipboard personnel and links to NSF program awards. In addition, non-proprietary data files, images, and derived products which are hosted locally or in national repositories, as well as science and technical reports, can be freely downloaded. On the Ridge 2000 database page, our Data Link allows users to search the database using a broad range of parameters including data type, cruise ID, chief scientist, geographical location. The first Ridge 2000 field programs sailed in 2004 and, in addition to numerous data sets collected prior to the Ridge 2000 program, the database currently contains information on fifteen Ridge 2000-funded cruises and almost sixty Alvin dives. Track lines can be viewed using a recently- implemented Web Map Service button labelled Map View. The Ridge 2000 database is fully integrated with databases hosted by the mgDMS group for MARGINS and the Antarctic multibeam and seismic reflection data initiatives. Links are provided to partner databases including PetDB, SIOExplorer, and the ODP Janus system. Improved inter-operability with existing and new partner repositories continues to be strengthened. One major effort involves the gradual unification of the metadata across these partner databases. Standardised electronic metadata forms that can be filled in at sea are available from our web site. Interactive map-based exploration and visualisation of the Ridge 2000 database is provided by GeoMapApp, a freely-available Java(tm) application being developed within the mgDMS group. GeoMapApp includes high-resolution bathymetric grids for the 8-11N EPR segment and allows customised maps and grids for any of the Ridge 2000 ISS to be created. Vent and instrument locations can be plotted and saved as images, and Alvin dive photos are also available.

The intensification of deep-water mass changes in the deep Atlantic Ocean throughout the Mid-Pleistocene climate transition

NASA Astrophysics Data System (ADS)

Poirier, R. K.; Billups, K.

2012-12-01

We examine the deep-water hydrography at Ocean Drilling Project (ODP) Site 1063 (subtropical North Atlantic, ~4600 meter water depth) using high-resolution benthic stable isotope (δ18O, δ13C) and grain size (% coarse, % Sortable Silt - SS, SS mean diameter) analyses from ~490 to 740 ka. The benthic foraminiferal δ13C record from Site 1063 provides a proxy for changes in the relative flux of lower North Atlantic Deep Water (NADW) through time. This record will refine the timing of increases in the formation of the densest components of NADW on the orbital and millennial-scale. We explore whether or not grain size analyses provide a proxy for changes in the relative velocity of the deep current. The new stable isotope data from Site 1063, when combined with the records of Poli et al. (2000), Ferretti et al. (2005), and Billups et al. (2011), tuned to the global benthic isotope stack (LR05) of Liesicki and Raymo (2004), provides a complete deep water record spanning Marine Isotope Stage (MIS) 25 to MIS 8 (~1020 to ~240 ka). Compiling published records from 16 additional sites, we use the Ocean Data View (ODV) program (Schlitzer, 2012) to map deep-water mass distributions through time. Results reveal an increasing distribution and influence of the NADW in relation to the Antarctic Bottom Water mass within interglacial periods beginning at MIS 15 continuing though the end of the Site 1063 record within MIS 9. Preliminary grain size analyses over a short interval of time reveal regular high frequency variations on the millennial scale. We anticipate having complete, high-resolution stable isotope and grain size records to discuss the hydrographic changes within the MIS 16/15 glacial/interglacial transition, as well as throughout the Mid-Pleistocene transition (MPT).

Fracture patterns after bilateral sagittal split osteotomy of the mandibular ramus according to the Obwegeser/Dal Pont and Hunsuck/Epker modifications.

PubMed

Möhlhenrich, Stephan Christian; Kniha, Kristian; Peters, Florian; Ayoub, Nassim; Goloborodko, Evgeny; Hölzle, Frank; Fritz, Ulrike; Modabber, Ali

2017-05-01

The aim of this study was to compare the fracture patterns after sagittal split osteotomy according to Obwegeser/Dal Pont (ODP) and Hunsuck/Epker (HE), as well as to investigate the relationship between lateral bone cut ending or angle and the incidence of unfavorable/bad splits. Postoperative cone-beam computed tomograms of 124 splits according to ODP and 60 according to HE were analyzed. ODP led to 75.8% and HE led to 60% lingual fractures with mandibular foramen contact. Horizontal fractures were found in 9.7% and 6.7%, respectively, and unfavorable/bad splits were found in 11.3% and 10%, respectively. The lateral osteotomy angle was 106.22° (SD 12.03)° for bad splits and 106.6° (SD 13.12)° for favorable splits. Correlations were found between favorable fracture patterns and split modifications and between buccal ending of the lateral bone cut and bad splits (p < 0.001). No relationship was observed between split modifications (p = 0.792) or the osteotomy angle (p = 0.937) and the incidence of unfavorable/bad splits. Split modifications had no influence on the incidence of unfavorable/bad splits, but the buccal ending of the lateral bone cut did have an influence. More lingual fractures with mandibular foramen contact are expected with the ODP modification. The osteotomy angle did not differ between favorable and bad splits. Copyright © 2017 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

Pollen and palynofacies analyses of Paleocene-Eocene Thermal Maximum sediments from the North American continental shelf

NASA Astrophysics Data System (ADS)

Willard, D. A.; Robinson, M. M.; Self-Trail, J. M.; Wandless, G. A.; Sluijs, A.

2014-12-01

Analyses of pollen and palynofacies from Paleocene-Eocene Thermal Maximum (PETM) sediments from three cores collected on the Atlantic Coastal Plain provide insights into the timing of vegetation and hydrologic changes associated with the PETM in eastern North America. The Mattawoman Creek-Billingsley Road (MCBR2), South Dover Bridge (SDB), and Bass River (ODP Site 1074AX) cores were collected at progressively greater distances from the paleoshoreline in continental shelf deposits in Maryland and New Jersey, USA. The PETM carbon isotope excursion (CIE) at each site is accompanied by sharp increases in pollen and spore concentrations, as well as changes in terrestrial palynomorph assemblage composition. In the two sites proximal to the paleoshoreline in Maryland, CIE fern spore abundance was two- to three times greater than in pre-CIE assemblages. At the distal site at Bass River, fern spores are present in CIE sediments and absent in pre-CIE sediments. Angiosperm pollen is most common in CIE sediments at all three sites. Palynofacies analyses, which quantify contributions of organic material from marine and non-marine sources, indicate that terrestrial influx increased sharply at the CIE onset. This observation is consistent with seasonally increased runoff from the continent.

The timing of termination I in benthic δ18O of the Atlantic, Pacific, and Mediterranean basins

NASA Astrophysics Data System (ADS)

Konijnendijk, T.

2014-12-01

Terminations used to be regarded as effectively globally synchronous events. As such they were used (amongst other features) in aligning cores by Lisiecki and Raymo (2005) in their widely accepted global benthic stack. Skinner and Shackleton (2005) showed, however, that this assumption of synchronicity may not hold. In a detailed study of the last glacial-interglacial transition, an Atlantic record from the Iberian Margin and a record from the deep eastern equatorial Pacific - both dated by 14C for a solid, independent age estimate - show a significant discrepancy in timing: ~4,000 years. Indeed, in 2009 Lisiecki and Raymo published a separate reconstruction for the Atlantic and Pacific records in their stack, and found indications for diachronous termination signals for the last five terminations. We compared the Atlantic and Pacific records of Skinner and Shackleton (2005) to the benthic isotope record of ODP site 968 in the eastern Mediterranean published by Ziegler et al. (2010), to see how the Mediterranean record feeds into this discussion. The age model for this record is constrained by the carbon dated boundaries of saproprel 1 as well as correlation to the radiometrically dated cave record of Sanbao-Hulu (Wang et al., 2008). The benthic δ18O record of ODP site 968 resembles the Pacific record much more than the geographically closer Iberian Margin record. This raises questions: whether the Late Glacial/Early Holocene benthic record of MD99-2334K on the Iberian Margin is representative of Atlantic benthic δ18O; what oceanographic factors could have influenced the benthic δ18O of the sites involved; whether there is, after all, a globally synchronous, two-step deglaciation in the Mediterranean, Atlantic, and Pacific basins. Lisiecki and Raymo, 2005. DOI: 10.1029/2004PA001071 Lisiecki and Raymo, 2005. DOI: 10.1029/2009PA001732 Skinner and Shackleton, 2005: DOI: 10.1016/j.quascirev.2004.11.008 Wang et al. 2008: doi:10.1038/nature06692. Ziegler et al., 2010: DOI: 10.1016/j.quascirev.2010.03.011

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.

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.

Evidence for Millennial-Scale Climate Variability in the Surface Waters Above ODP Site 980, NE Atlantic Ocean During the Last Glacial Interval (MIS 4-2)

NASA Astrophysics Data System (ADS)

Michaud, J. R.; Cullen, J. L.; McManus, J. F.; Oppo, D. W.

2004-05-01

Successful efforts to recover quality high sedimentation rate deep-sea sediment sections from the North Atlantic over the last decade have produced a number of studies demonstrating that climate instability at sub-orbital and even millennial time-scales is a pervasive component of Late Pleistocene North Atlantic climate. This is particularly true during Marine Isotope Stages (MIS) 4-2, i.e., the last glacial interval. One such high sedimentation rate section was recovered at ODP Site 980, Northeast Atlantic Ocean where sedimentation rates during MIS 4-2 exceed 15cm/kyr. Recently, we have begun to generate more detailed records from MIS 4-2 at Site 980 by reducing our sampling interval from 20 to around 2.5 cm, improving the resolution of our records an order of magnitude, from 1200-1300 to 100-200 years. 300 samples were used to generate high resolution records of changes in the input of ice-rafted detritus (IRD), along with limited data documenting changes in the relative abundance of the N. pachyderma, left coiling, which can be evaluated within the context of our previously generated lower resolution planktic and benthic oxygen isotope records used to generate our age model for this interval. Our previously published low resolution IRD record enabled us to identify Heinrich events 1-6 within the sediment interval deposited during the last glacial. Each event is characterized by IRD concentrations ranging from 500 to over 2500 lithic grains >150 microns per gram sediment. Superimposing our new high resolution IRD record reveals that Heinrich events 3,2,1 occurring at approximately 32, 23, and 17 kya, respectively, are each composed of a series of separate abrupt rapid increases in IRD concentrations approaching 1,000 grains per gram. An additional comparable event occurring at approximately 20 kya has also been identified. In the early part of the last glacial H6, H5, and H4 occurring at approximately 66, 47, and 38 kya, respectively, are recorded as much more abrupt and rapid increases in IRD concentrations to 2,000 or greater lithic grains per gram than were observed in our previous record. There are two 5 kyr intervals between H6 and H5 that contain little or no IRD. An additional abrupt IRD event is recorded at approximately 34 kya. Thus, our new IRD record is recording a series of additional episodic increases in IRD concentrations comparable in intensity to the identified Heinrich events. This suggests that ODP Site 980 sediments are recording a series of more closely spaced episodic increases in IRD concentration that can be directly related to the Dansgaard/Oeschger events recorded in Greenland ice cores. Comparison of our preliminary high resolution record of changes in the relative abundance of the polar species N. pachyderma, left coiling, to our IRD record suggests that the input of iceberg bearing waters precedes the increases in the relative abundance of N. pachyderma, left coiling for the early glacial IRD events. Whereas the abrupt increases in N. pachyderma, left coiling seem to occur during the later glacial IRD events. Thus, in the early glacial the influx of icebergs seem to occur before the invasion of cooler surface waters as opposed to the same time later in the glacial.

Characterization of Paleoredox Changes In Nw-pacific Deep-sea Sediments Using Environmental Magnetic In Combination With Geochemical-mineralogic Data

NASA Astrophysics Data System (ADS)

Urbat, M.; Pletsch, T.

The understanding of environmental and oceanic controls on deep-sea sediments in the NW Pacific Ocean (ODP Site 1149A, Nadezhda Basin) benefits from the inte- gration of environmental magnetic methodology with geochemical-mineralogic XRD (x-ray defraction) and XRF (x-ray fluorescence) data. Crucially, the inherently grad- ual diagenetic processes related to paleo-redox changes in the sediment column may be more sensitively monitored using the integration of non-magnetic and magnetic data, because they do reflect various aspects of the entire postdepositional alteration. The studied 32 m long quaternary interval at Hole ODP 1149A provides an expanded record of eolian dust supply from the Asian continent, siliceous plankton accumulation and varying contributions of both discrete ash layers and disperse ash to a truly deep- sea environment (Plank et al. 2000). Recurrent diagenetic intervals appear to be related to changes in the Ocean water circulation (Kuriosho current) and concomitant produc- tivity variations as a function of glacial-interglacial paleoclimatic changes. Diagenetic intervals correspond to paleo-redox boundaries, where suboxic conditions promoted the destruction of the primary magnetic signal (iron oxides) and the precipitation of rhodochrosite (MnCO3). We used simple normative calculations on the basis of of Al and Cr contents to discriminate between the major groups of components (terrigenous, volcanogenic, biogenic, diagenetic) in combination with our magnetic results. These results form the grounds for the discrimation and independent interpretation of the genetically various sediment components in the paleoceanograhic context.

Constraints On Fluid Evolution During Mid-Ocean Ridge Hydrothermal Circulation From Anhydrite Sampled by ODP Hole 1256D

NASA Astrophysics Data System (ADS)

Smith-Duque, C.; Teagle, D. A.; Alt, J. C.; Cooper, M. J.

2008-12-01

Anhydrite is potentially a useful mineral for recording the evolution of seawater-derived fluids during mid- ocean ridge hydrothermal circulation because it exhibits retrograde solubility, and hence may precipitate due to the heating of seawater or the sub-surface mixing of seawater with black smoker-like fluids. Here we provide new insights into the chemical and thermal evolution of seawater during hydrothermal circulation through analyses of anhydrite recovered from ODP Hole 1256D, the first complete penetration of intact upper oceanic crust down to gabbros. Previously, crustal anhydrite has been recovered only from Hole 504B. Measurements of 87Sr/86Sr, major element ratios, Rare Earth Elements and δ18O in anhydrite constrain the changing composition of fluids as they chemically interact with basalt. Anhydrite fills veins and pore-space in the lower lava sequences from ~530 to ~1000 meters sub- basement (msb), but is concentrated in the lava-dike transition (754 to 811 msb) and uppermost sheeted dikes. Although present in greater quantities than in Hole 504B, the amount of anhydrite recovered from the Site 1256 crust is low compared to that predicted by models of hydrothermal circulation (e.g., Sleep, 1991). Two distinct populations of anhydrite are indicated by measurements of 87Sr/86Sr suggesting different fluid evolution paths within Site 1256. One group of anhydrites have 87Sr/86Sr of 0.7070 to 0.7085, close to that of 15 Ma seawater (0.70878), suggesting that some fluids penetrate through the lavas and into the sheeted dikes with only minimal Sr-exchange with the host basalts. A second group, with low 87Sr/86Sr between 0.7048 and 0.7052, indicates precipitation from a fluid that has undergone far greater interaction with basalt. This range is close to that estimated from Sr-isotopic analyses of epidote for the Hole 1256D hydrothermal fluids (87Sr/86Sr ~0.705). Sr/Ca and 87Sr/86Sr indicate a similar relationship to that seen at ODP Hole 504B suggesting that Sr/Ca ratios reduce greatly during recharge before there is significant Sr exchange with the host basalts. δ18O measurements display an irregular trend with depth from +17‰ in the lower volcanics to +10‰ in the sheeted dikes suggesting an increase in precipitation temperatures from 105 to 211°C. One sample, from a chalcopyrite mineralized dike margin has a very light δ18O of +2.2‰ suggesting a temperature of ~408°, perhaps indicating that fluid was superheated following direct contact with the hot intrusive body. This sample also records low 87Sr/86Sr and high total REE.

Sedimentary Characterization of Nazca Ridge ODP Site 1237: Plio-Pleistocene Record of Continental Erosion and Bottom Water Influence

NASA Astrophysics Data System (ADS)

Dileo, K. V.; Joseph, L. H.

2005-12-01

Ocean Drilling Program (ODP) Site 1237 (16°0.421'S, 76°22.685'W), drilled ~140 km off the east coast of Peru on the easternmost flank of Nazca Ridge, provides an opportunity to study climatic shifts in the southeastern Pacific Ocean over the last thirty million years. Sediment deposition at this location has been influenced by movement through various oceanic current systems, from a relatively low productivity open ocean setting to a high productivity upwelling zone along the coast of Peru, as the tectonic plate subducts under South America. Today, near the eastern edge of the Peru-Chile current at a water depth of 3212 m, this site is located in the transition zone between Antarctic Circumpolar Deep Water and Pacific Central Water and is close enough to the continent to collect terrigenous sediment from South America. Plio-Pleistocene sediment (~100 mcd) from Site 1237 is comprised of white to light greenish gray clayey nannofossil ooze (Lithologic Unit IB) and clay to ooze with similar percentages of clay minerals, nannofossils, and diatoms (Unit IA). Shipboard results indicated linear sedimentation rates of ~20-30 m/my and siliciclastic mass accumulation rates (MARs) of ~1 g/cm2/ky during this time period. Approximately 90 Plio-Pleistocene samples were analyzed for bulk magnetic susceptibility, anisotropy of magnetic susceptibility (AMS; P' and T), organic carbon content, and calcium carbonate content to aid in interpretation of climatic and oceanic conditions that existed at the time of sediment deposition. Bulk magnetic susceptibility values are very low (10-6 to 10-7 SI, or negative) at the base of the record through ~60 mcd(~3 Ma), gradually increase to a peak value of ~3.7 x 10-4 SI at ~22 mcd (~1 Ma), decreasing and subsequently increasing for the remainder of the record. In the upper part of the record (above 60 mcd) where bulk magnetic susceptibility values are >10-6, P' values (strength of magnetic susceptibility), which can be used to interpret the strength of the depositing current, range from ~1.005 to ~1.051 and indicate that most samples have experienced current influence from bottom water currents. Calcium carbonate percentages are high (~90%) at the base of the record, decline gradually from ~60 until ~30 mcd (~1.2 Ma), and maintain a low percentage (~10%) for the remainder of the record although calcareous nannofossils are still abundant. Although not described shipboard as a lithologic boundary, a number of gradual, but distinct, changes in the characteristics analyzed in this study occur at ~3 Ma. Increased ash input from 3 to 1 Ma is not likely the only reason for the changes noted, although the ash may be indicative of increased activity and mountain building in the Columbian Andes; detailed terrigenous MARs will aid in interpretation of continental conditions at this time. Tighter age control and grain size analyses (combined with the AMS results) may provide insight into the effects of Northern Hemisphere glaciation on oceanic currents off the coast of Peru.

A Holocene record of ocean productivity and upwelling from the northern California continental slope

USGS Publications Warehouse

Addison, Jason A.; Barron, John A.; Finney, Bruce P.; Kusler, Jennifer E.; Bukry, David; Heusser, Linda E.; Alexander, Clark R.

2018-01-01

The Holocene upwelling history of the northern California continental slope is examined using the high-resolution record of TN062-O550 (40.9°N, 124.6°W, 550 m water depth). This 7-m-long marine sediment core spans the last ∼7500 years, and we use it to test the hypothesis that marine productivity in the California Current System (CCS) driven by coastal upwelling has co-varied with Holocene millennial-scale warm intervals. A combination of biogenic sediment concentrations (opal, total organic C, and total N), stable isotopes (organic matter δ13C and bulk sedimentary δ15N), and key microfossil indicators of upwelling were used to test this hypothesis. The record of biogenic accumulation in TN062-O550 shows considerable Holocene variability despite being located within 50 km of the mouth of the Eel River, which is one of the largest sources of terrigenous sediment to the Northeast Pacific Ocean margin. A key time interval beginning at ∼2900 calibrated years before present (cal yr BP) indicates the onset of modern upwelling in the CCS, and this period also corresponds to the most intense period of upwelling in the last 7500 years. When these results are placed into a regional CCS context during the Holocene, it was found that the timing of upwelling intensification at TN062-O550 corresponds closely to that seen at nearby ODP Site 1019, as well as in the Santa Barbara Basin of southern California. Other CCS records with less refined age control show similar results, which suggest late Holocene upwelling intensification may be synchronous throughout the CCS. Based on the strong correspondence between the alkenone sea surface temperature record at ODP Site 1019 and the onset of late Holocene upwelling in northern California, we suggest that CCS warming may be conducive to upwelling intensification, though future changes are unclear as the mechanisms forcing SST variability may differ.

Frictional behavior of carbonate-rich incoming sediment in the Hikurangi subduction zone

NASA Astrophysics Data System (ADS)

Rabinowitz, H. S.; Savage, H. M.; Carpenter, B.; Ikari, M.; Collettini, C.

2017-12-01

In recent years, the traditional view of the seismogenic zone has been challenged by observations of a range of seismic behaviors both above and below the depths previously considered capable of nucleating earthquakes. The Hikurangi trench is one of the few subduction zones where this transitional seismic behavior has been observed at the shallowest portions of the subduction zone, providing an opportunity to investigate the mechanical controls on seismic behavior through measurements of directly sampled sediment. To this end, an IODP cruise (March-May, 2018; Exp. 375) will recover sample from the faults that participate in this shallow seismic behavior. In order to obtain preliminary frictional characterization of the sedimentary inputs to the Hikurangi Trench, we conducted deformation experiments on samples from an ocean drill core through the incoming sediments (ODP Site 1124). The sedimentary package subducting at Hikurangi contains carbonate-rich lithologies, which have been shown to be more frictionally unstable (velocity-weakening, high healing rates) than the clays that comprise the majority of the sedimentary inputs to global subduction zones. Such frictional properties could promote seismic behavior in the shallower reaches of the subduction zone. We focus on a section of ODP Site 1124 which has a carbonate content of 40 wt% to investigate the effect of this lithology. Samples were saturated with distilled water mixed with 35 g/l sea salt. Velocity-stepping and slide-hold-slide tests were performed in multiple biaxial and triaxial deformation apparatus to investigate a range of pressures, temperatures and velocities relevant to the shallow subduction zone (σeff = 1-150 MPa, sliding velocities of 1.7 nm/s-300 μm/s, hold times of 1-1000 s, and T = 20-100 ºC). We observe transitions from velocity-strengthening to velocity-weakening behavior over these conditions which could contribute to shallow seismic behavior in the Hikurangi trench.

A Holocene record of ocean productivity and upwelling from the northern California continental slope

NASA Astrophysics Data System (ADS)

Addison, J. A.; Barron, J. A.; Finney, B.; Kusler, J. E.; Bukry, D.; Heusser, L. E.; Alexander, C. R., Jr.

2016-12-01

The Holocene upwelling history of the northern California continental slope is examined using a 7-m-long marine sediment core (TN062-O550; 40.9°N, 124.6°W, 550 m water depth) collected offshore from Eureka, CA, that spans the last 7,400 calibrated years before present (cal yrs BP). A combination of biogenic sediment concentrations (opal, total organic C, and total N), stable isotopes (organic matter δ13C and bulk sedimentary δ15N), and key microfossil indicators of upwelling were used to test the hypothesis that marine productivity in the California Current System (CCS) driven by coastal upwelling has co-varied with global Holocene millennial-scale warm intervals. Results show biogenic sediment accumulation in TN062-O550 varied considerably during the Holocene, despite being located within 50 km of the mouth of the Eel River, one of the largest sources of terrigenous sediment to the Northeast Pacific Ocean margin. A key time interval beginning at 2900 cal yr BP indicates the onset of modern upwelling in the CCS, and that this period also corresponds to the most intense period of upwelling in the last 7,400 years. When these results are placed into a regional CCS context during the Holocene, it was found that the timing of upwelling intensification as recorded in TN062-O550 corresponds closely to that seen at nearby ODP Site 1019 as well as in the Santa Barbara Basin of southern California. Other CCS records with less high-quality age control show similar results, which suggest late Holocene upwelling intensification may be synchronous throughout the CCS. Based on the strong correspondence between the alkenone-derived sea surface temperature record at ODP Site 1019 and the onset of late Holocene upwelling in northern California, we tentatively suggest that regional CCS warming may be conducive to upwelling intensification in the future.

Fish production and diversity in the Paleocene-Eocene Thermal Maximum—Increased production but no novel faunas during a "Future Earth" analog

NASA Astrophysics Data System (ADS)

Tomczik, D. W.; Norris, R. D.; Gaskell, D. E.

2014-12-01

A partial analog for future global change is the Paleocene-Eocene Thermal Maximum—a transient episode of warming, acidification, and biogeographic change at ~55.5 Ma. The PETM is known to have triggered extinction in some deep sea biotas, extensive biogeographic range shifts, and the common occurrence of 'excursion biotas'—non-analog occurrences of species that are typically rare in the open ocean before or after the PETM. Here we report on the impact of the PETM on fish production and biodiversity. Our data include the mass accumulation rate of fish teeth and denticles as well as an analysis of tooth morphotypes for three PETM sites: ODP 1220 and 1209 in the Pacific, and ODP 1260 in the equatorial Atlantic. Tooth morphotypes hardly change through the PETM and consist of abundant midwater species (angler fish and flashlight fish) in addition to sharks and epipelagic fish. There is no evidence for a non-analog 'excursion biota' during the PETM, suggesting that fish experienced fewer geographic range shifts than the calcareous and organic-walled plankton where excursion biotas are commonplace. Fish mass accumulation rates are also relatively stable before and after the PETM although all sites show a transient rise in fish production at the onset of the PETM or within the later part of the "PETM Core". These results broadly match published estimates of PETM export production from biogenic barium fluxes. Our findings run counter to "Future Earth" models that use climate forecasts for the next century to predict the impact of global change on fish stocks. These models suggest that future warming and ocean stratification will decrease most tropical and subtropical ocean fish production, accentuate fish production in the boundary currents and generally shift production toward higher latitudes. A resolution of "Future Earth" models and PETM data may reflect the different timescales of observation and stages of ecological response to severe global change.

Paleomagnetic and rock magnetic results from Koko Seamount (ODP Leg 197, Site 1206): Implications for hotspot motion

NASA Astrophysics Data System (ADS)

Olton, G.; Cottrell, R. D.; Tarduno, J. A.; Carvallo, C.; Torii, M.; Doubrovine, P. V.

2002-12-01

ODP Leg 197 sought to test whether the Hawaiian hotspot was fixed in the mantle during Late Cretaceous to Early Tertiary times. The principal goal was the recovery of basalt sequences from several of the Emperor seamounts and the main tool to be applied was paleomagnetism. Koko Seamount, near the bend in the Hawaiian-Emperor Seamounts, was the southernmost site drilled during Leg 197. Fifteen basalt units separated by thick volcaniclastic units were recovered in 278 m of penetration. Based on nannofossil stratigraphy of the sediments above basalt, the top of the volcanic section is 43.5-49.7 m.y.-old. Shipboard geochemical analyses (Initial Reports, Leg 197) indicate the lavas include tholeiites, suggesting that the age of the sequence recovered is similar to that of the major phase of shield building. Detailed, stepwise alternating field demagnetization experiments, and subsequent principal component analysis (all conducted aboard the JOIDES Resolution) yielded 14 inclination groups suggesting a mean paleolatitude of 21.7o N, slightly steeper than that the present-day latitude of Hawaii. Shore-based hysteresis measurements of basalt samples indicate single to pseudo-single domain behavior (mean Hc = 170 Oe, Hcr = 309 Oe, Mr/Ms = 0.274), whereas unblocking temperatures range from 200-300 oC and 550-600 oC. These data suggest the presence of high titanium titanomagnetite and magnetite. Shore-based thermal demagnetization inclinations are similar to the shipboard alternating field demagnetization data. The paleomagnetic data from Koko Seamount, together with results from Detroit, Suiko and Nintoku Seamounts form a southward decreasing series of paleolatitudes that appear to track motion of the Hawaiian ``hotspot" in the mantle. Rates of motion based on paleolatitudes of the Emperor Seamounts range from 30-50 mm/yr, similar to that observed for some continental plates.

New insights on late stage volcanism in the Pigafetta basin, western Pacific

NASA Astrophysics Data System (ADS)

Stadler, T.; Tominaga, M.

2014-12-01

We document observations of late stage volcanism in the western Pacific Pigafetta Basin by integrating previously published and new multichannel seismic (MCS) reflection profiles, Ocean Drilling Program (ODP) drill core, and well log data. We examine data from three seismic experiments (FM35-12, MESOPAC II, and MTr5) conducted in the Pigafetta Basin, one of the oldest, deepest abyssal basins in the world, where crustal age is suggested to range from M29 (~157 Ma) to M44 (~169.8 Ma) based on Japanese Mesozoic magnetic lineations. We use a total of ~2150 km of MCS lines along with core and wire-line logging data from ODP Hole 801C. As a basis for our interpretation, we use previously defined seismic stratigraphy for the Pigafetta Basin, including Horizon B (basement) and lower transparent unit (volcaniclastic turbidites) terminology. We build synthetic seismograms from density and p-wave velocity logs using OpendTect v 4.6.0 tie well to seismic feature. We then incorporate energy and similarity attributes of the MCS profiles with the modeled seismogram to correlate reflectors to ODP Hole 801C lithostratigraphy. From this correlation, to be consistent with previous studies, we assign lithology and age to prominent sedimentary and basement reflectors throughout all survey lines. We characterize widely distributed deformation of Horizon B and lower sedimentary unit reflectors based on coherency of wiggle traces, lateral and vertical energy attenuation, and dip of reflectors over a range of scales (>10 km to <1 km). Our findings provide new evidence of late stage volcanism occurring in the Pigafetta Basin during the mid-Cretaceous (110 - 90 Ma). We classify late stage volcanism into 3 types of volcanic related features: (1) seamounts, (2) sills, and (3) vertical seismic disturbance zones (<<1 km wide) characterized by bilateral upward drag of reflectors (indicating a thin, vertical volcanic intrusion). The distribution of these features provide new insights into Cretaceous volcanism in the Pigafetta Basin: (i) late stage volcanism is more widely distributed and younger than previously reported, (ii) findings indicate a local source of magma, and (iii) the modes of volcanism differ from previously documented flood basalts and massive flows.

Quantitative analysis of fragrance in selectable one dimensional or two dimensional gas chromatography-mass spectrometry with simultaneous detection of multiple detectors in single injection.

PubMed

Tan, Hui Peng; Wan, Tow Shi; Min, Christina Liew Shu; Osborne, Murray; Ng, Khim Hui

2014-03-14

A selectable one-dimensional ((1)D) or two-dimensional ((2)D) gas chromatography-mass spectrometry (GC-MS) system coupled with flame ionization detector (FID) and olfactory detection port (ODP) was employed in this study to analyze perfume oil and fragrance in shower gel. A split/splitless (SSL) injector and a programmable temperature vaporization (PTV) injector are connected via a 2-way splitter of capillary flow technology (CFT) in this selectable (1)D/(2)D GC-MS/FID/ODP system to facilitate liquid sample injections and thermal desorption (TD) for stir bar sorptive extraction (SBSE) technique, respectively. The dual-linked injectors set-up enable the use of two different injector ports (one at a time) in single sequence run without having to relocate the (1)D capillary column from one inlet to another. Target analytes were separated in (1)D GC-MS/FID/ODP and followed by further separation of co-elution mixture from (1)D in (2)D GC-MS/FID/ODP in single injection without any instrumental reconfiguration. A (1)D/(2)D quantitative analysis method was developed and validated for its repeatability - tR; calculated linear retention indices (LRI); response ratio in both MS and FID signal, limit of detection (LOD), limit of quantitation (LOQ), as well as linearity over a concentration range. The method was successfully applied in quantitative analysis of perfume solution at different concentration level (RSD≤0.01%, n=5) and shower gel spiked with perfume at different dosages (RSD≤0.04%, n=5) with good recovery (96-103% for SSL injection; 94-107% for stir bar sorptive extraction-thermal desorption (SBSE-TD). Copyright © 2014 Elsevier B.V. All rights reserved.

Ocean Nitrogen Isotopic Change in the Early Eocene

NASA Astrophysics Data System (ADS)

Kast, E.; Stolper, D. A.; Higgins, J. A.; Ren, H. A.; Wang, X. T.; Sigman, D. M.

2017-12-01

The long term variability of the marine nitrogen (N) cycle is an open question. The Cenozoic provides a well-studied framework for investigating the marine N cycle over long time scales and across large climate transitions. However, only sparse bulk Cenozoic sediment δ15N data exist, the utility of which for reconstructing environmental conditions is unclear. We present a record of foraminifera-bound organic matter δ15N from the Paleocene to late Eocene. At three distant sites, foraminifera-bound δ15N decreases dramatically between 56 Ma and 50 Ma: from 14‰ to 2‰ in the northwest Pacific (ODP site 1209), from 12‰ to 4‰ in the southeast Atlantic (ODP site 1263), and from 9‰ to 4‰ in the northwest Atlantic (IODP site U1409). This foraminifera-bound δ15N change is on par, if not greater, than the largest changes that have been observed in bulk sediment δ15N over the last 600 million years. The shared change among the sites implies a change in mean δ15N of oceanic fixed N, which is thought to be sensitive to the ratio of water column to sedimentary denitrification, with a higher δ15N reflecting a greater proportion of denitrification occurring in the water column. Today, water column denitrification occurs in the shallow subsurface, in regions where these waters are suboxic. Thus, the δ15N decrease may reflect a slowing of water column denitrification, which can be generated by a decline in shallow subsurface suboxia. A key factor in the extent of shallow subsurface suboxia is the amount of "preformed oxygen," the initial concentration of dissolved O2 in the water that flows from the surface into the shallow subsurface: a decline in suboxia would require a rise in preformed oxygen from 56 to 50 Ma. The δ15N decline occurs before the onset of cooling in the Eocene, eliminating global temperature change as the driver of increased preformed oxygen. Instead we favor explanations that involve tectonically driven changes in continental configuration and shallow and mid-depth ocean bathymetry. Indeed, the δ15N decline appears coincident with the initiation of bathymetric effects from the collision of India with Asia. This category of explanation is consistent with the overlap of the δ15N decline with the previously identified increase in marine barite δ34S at 51 Ma.

Intraplate volcanism of the western Pacific: New insights from geological and geophysical observations in the Pigafetta Basin

NASA Astrophysics Data System (ADS)

Stadler, Timothy J.; Tominaga, Masako

2015-09-01

Understanding intraplate volcanism is a key to deciphering the Earth's magmatic history. One of the largest intraplate volcanic events occurred during the mid-Cretaceous, roughly 75-125 Ma in the western Pacific. To investigate the origin of this volcanism we present the first comprehensive study of volcanism in the Pigafetta Basin using seismic surveys, magnetic and gravity modeling, and Ocean Drilling Program (ODP) drill core and well log data from Site 801. Our results show that intraplate volcanism in the Pigafetta Basin coincides with the rest of the western Pacific seamount provinces, supporting the previously suggested plumelets scenario for the origin of intraplate volcanism during the mid-Cretaceous volcanic events. Our magnetic modeling suggests that the late-stage volcanism does not overprint the remanant magnetization acquired by the Jurassic ocean crust in the Pigafetta Basin, and hence, marine magnetic anomalies recorded in the Jurassic basement are preserved. Also, the formerly identified Rough-Smooth Boundary (RSB) is indistinguishable from any other rough-smooth topographic boundaries throughout the survey area suggesting that the RSB is unlikely to be a Cretaceous sill-Jurassic basement boundary. Lastly, the apparent ages and spatial distribution of volcanic features suggests a dynamic history of hydrothermal circulation in the Pigafetta Basin, indicating that hydrothermal circulation was ongoing well past 100 Ma.

Atmospheric chemistry of short-chain haloolefins: photochemical ozone creation potentials (POCPs), global warming potentials (GWPs), and ozone depletion potentials (ODPs).

PubMed

Wallington, T J; Sulbaek Andersen, M P; Nielsen, O J

2015-06-01

Short-chain haloolefins are being introduced as replacements for saturated halocarbons. The unifying chemical feature of haloolefins is the presence of a CC double bond which causes the atmospheric lifetimes to be significantly shorter than for the analogous saturated compounds. We discuss the atmospheric lifetimes, photochemical ozone creation potentials (POCPs), global warming potentials (GWPs), and ozone depletion potentials (ODPs) of haloolefins. The commercially relevant short-chain haloolefins CF3CFCH2 (1234yf), trans-CF3CHCHF (1234ze(Z)), CF3CFCF2 (1216), cis-CF3CHCHCl (1233zd(Z)), and trans-CF3CHCHCl (1233zd(E)) have short atmospheric lifetimes (days to weeks), negligible POCPs, negligible GWPs, and ODPs which do not differ materially from zero. In the concentrations expected in the environment their atmospheric degradation products will have a negligible impact on ecosystems. CF3CFCH2 (1234yf), trans-CF3CHCHF (1234ze(Z)), CF3CFCF2 (1216), cis-CF3CHCHCl (1233zd(Z)), and trans-CF3CHCHCl (1233zd(E)) are environmentally acceptable. Copyright © 2015 Elsevier Ltd. All rights reserved.

Incidence and evolution of subretinal precipitates in optic disc pit maculopathy.

PubMed

Chatziralli, Irini; Theodossiadis, George; Brouzas, Dimitrios; Theodossiadis, Panagiotis

2017-06-26

To study the evolution of subretinal precipitates coexistent with optic disc pit (ODP) maculopathy from their appearance at baseline examination until their absorption after successful treatment. Participants in this retrospective, multicenter study were 42 patients with ODP maculopathy, in whom complete ocular examination was performed, including visual acuity (VA) measurement, slit-lamp examination, color or red-free fundus photography, and optical coherence tomography at baseline after surgical treatment. Out of 42 cases, 17 (40.5%) cases of ODP maculopathy, which were examined between 2002 and 2015, were found to have subretinal precipitates associated with multilayer fluid accumulation at baseline. Precipitates were located at the outer part of the photoreceptor layer and remained for 3-6 months after successful treatment and absorption of subretinal fluid. The mean VA was 0.99 ± 0.21 logMAR at baseline and improved to 0.54 ± 0.25 logMAR at the final examination. Macular precipitates in association with signs of disease chronicity, such as multilayer fluid accumulation, became evident at baseline examination. Precipitates' disappearance in 15 out of 17 cases coincided with the absorption of subretinal fluid. The relative low VA at baseline probably could be attributed to the chronicity of the disease.

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.

Sediment transport time measured with U-Series isotopes: Resultsfrom ODP North Atlantic Drill Site 984

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

DePaolo, Donald J.; Maher, Kate; Christensen, John N.

High precision uranium isotope measurements of marineclastic sediments are used to measure the transport and storage time ofsediment from source to site of deposition. The approach is demonstratedon fine-grained, late Pleistocene deep-sea sediments from Ocean DrillingProgram Site 984A on the Bjorn Drift in the North Atlantic. The sedimentsare siliciclastic with up to 30 percent carbonate, and dated by sigma 18Oof benthic foraminifera. Nd and Sr isotopes indicate that provenance hasoscillated between a proximal source during the last three interglacialperiods volcanic rocks from Iceland and a distal continental sourceduring glacial periods. An unexpected finding is that the 234U/238Uratios of the silicatemore » portion of the sediment, isolated by leaching withhydrochloric acid, are significantly less than the secular equilibriumvalue and show large and systematic variations that are correlated withglacial cycles and sediment provenance. The 234U depletions are inferredto be due to alpha-recoil loss of234Th, and are used to calculate"comminution ages" of the sediment -- the time elapsed between thegeneration of the small (<_ 50 mu-m) sediment grains in the sourceareas by comminution of bedrock, and the time of deposition on theseafloor. Transport times, the difference between comminution ages anddepositional ages, vary from less than 10 ky to about 300 to 400 ky forthe Site 984A sediments. Long transport times may reflect prior storagein soils, on continental shelves, or elsewhere on the seafloor. Transporttime may also be a measure of bottom current strength. During the mostrecent interglacial periods the detritus from distal continental sourcesis diluted with sediment from Iceland that is rapidly transported to thesite of deposition. The comminution age approach could be used to dateQuaternary non-marine sediments, soils, and atmospheric dust, and may beenhanced by concomitant measurement of 226Ra/230Th, 230Th/234U, andcosmogenic nuclides.« less

Drilling Polar Oceans with the European Research Icebreaker AURORA BOREALIS: the IODP Context

NASA Astrophysics Data System (ADS)

Lembke-Jene, Lester; Wolff-Boenisch, Bonnie; Azzolini, Roberto; Thiede, Joern; Biebow, Nicole; Eldholm, Olav; Egerton, Paul

2010-05-01

Polar oceans are characterized by extreme environmental conditions for humans and materials, and have remained the least accessible regions to scientists of the IODP. DSDP and ODP have for long faced specific technical and logistical problems when attempting to drill in ice-covered polar deep-sea basins. The Arctic Ocean and large areas of the high-latitude Southern Ocean remained largely un-sampled by ODP and remain one of the major scientific and technological challenges for IODP. Drilling in these regions has been discussed and anticipated for decades and the scientific rationales are reflected in the science plans of the international Nansen Arctic Drilling Program (NAD) or the Arctic Program Planning Group (APPG) of ODP/IODP, amongst others. More recently, the rationale to investigate the polar oceans in a holistic approach has been outlined by workshops, leading to strategic assessments of the scientific potential and new drilling proposals. The European Polar Board took the initiative to develop a plan for a novel and dedicated research icebreaker with technical capabilities hitherto unrealised. This research icebreaker will enable autonomous operations in the central Arctic Ocean and the Southern Ocean, even during the severest ice conditions in the deep winter, serving all marine disciplines of polar research including scientific drilling: The European Research Icebreaker and Deep-Sea Drilling Vessel AURORA BOREALIS. AURORA BOREALIS is presently planned as a multi-purpose vessel. The ship can be deployed as a research icebreaker in all polar waters during any season of the year, as it shall meet the specifications of the highest ice-class attainable (IACS Polar Code 1) for icebreakers. During the times when it is not employed for drilling, it will operate as the most technically advanced multi-disciplinary research vessel in the Arctic or polar Southern Ocean. AURORA BOREALIS will be a "European scientific flagship facility" (fully open to non-European partners), a multidisciplinary platform for studies ranging from the sub-seafloor into the atmosphere. AURORA BOREALIS was planned for her role in deep-sea drilling in consultation with engineers and technical experts familiar with the program and the operation of these vessels. All techniques currently deployed on IODP expeditions can be implemented onboard the vessel under polar weather and ice conditions, including the full range of re-entry, casing and cementing, and instrumentation options and the entire suite of downhole logging tools. Due to sufficient laboratory space, a full analytical workflow can be easily established comparable to existing permanent platforms, including clean rooms, diverse scanning and logging or incubation facilities. While the vessel is equipped with a dedicated deep-sea drilling rig, other coring and drilling techniques can be employed if needed (e.g. Rockdrill, MEBO, large diameter Kasten cores). AURORA BOREALIS is fitted to operate a CALYPSO Piston Coring System in polar waters. Future mud-return systems under consideration and testing for IODP to provide controlled borehole conditions in difficult facies are compatible with the layout of AURORA BOREALIS. The berthing capacity of 120 personnel total (scientists, technical support and crew) allows to accommodate a sufficient number of science party members offshore. The present scientific implementation documents plan for about one polar scientific drilling expedition per year in a to-be-determined configuration. As the vessel is a multi-dsiciplinary platform, operations for the entire year are not dependant on drilling operations alone. While principal access to the vessel will be based on a competitive proposal review and evaluation system, the allocation of timeslots specifically for drilling would preferably be given over to IODP handling and planning systems in a cooperative mode using the strengths and capacitites of the future program. Depending on interests and needs of the scientific communities a preferential focus in non-drilling expedition planning could be established e.g. for dedicated geophysical pre-site survey works in areas inaccessible by other vessels to secure critical data needed for later drilling expeditions. Based on ongoing expert consultations, it is safe to assume that the average costs for an Arctic or polar drilling expedition will be considerably lower than with an otherwise necessary multi-ship setup based on modelled expedition scenarios and annual operational cost calculations. Still, AURORA BOREALIS shall provide substantially enhanced scientific, operational, personnel and technical capacities offshore.

Reconstruction of western Pacific and Atlantic Ocean Surface Stability during the Miocene to Quaternary based on nannofossil assemblages

NASA Astrophysics Data System (ADS)

Sato, T.; Pratiwi, S. D.; Effendi, R.

2015-12-01

We studied in detail the calcareous nannofossil assemblages of the middle Miocene to Quaternary sequences of ODP Sites 782, 1005, 1006, and 1007 located in western Pacific Ocean and Bahama Bank of Caribbean Sea. Site 1007, 1005, 1006 are situated in the cross section of Bahama Bank from near shore to offshore site. Discoaster species, which is interpreted as lower photic zone species, is increasing the relative number towards the offshore site. This means that the abundant occurrence of Discoaster specimens indicates the well stratified surface water conditions. We also correlated the variability of maximum size of "Reticulofenestra" specimens between Sites 782, 1005, 1006, and 1007 (Fig ). The variability of the maximum size of Reticulofenestra recorded in site 782 is positive correlation with those in Site 1006, 1005, and 1007. As the occurrence of large size Reticulofenestra indicate the oligotrophic and stable sea surface condition, the drastic decreasing of maximum size of Reticulofenestra fond in 2.75Ma, 3.6Ma, 5.4Ma, 9Ma and 13Ma, indicates the collapse of stable and low nutrient sea surface conditions at these ages in both Caribbean Sea and western Pacific Ocean. The events found in the sequences are correlated to closure of Central American seaway, Messinian salinity crisis, intensify the Asian Monsoon, and closure of Indonesian Sea way.

Evaluating climatic response to external radiative forcing during the late Miocene to early Pliocene: New perspectives from eastern equatorial Pacific (IODP U1338) and North Atlantic (ODP 982) locations

NASA Astrophysics Data System (ADS)

Drury, Anna Joy; John, Cédric M.; Shevenell, Amelia E.

2016-01-01

Orbital-scale climate variability during the latest Miocene-early Pliocene is poorly understood due to a lack of high-resolution records spanning 8.0-3.5 Ma, which resolve all orbital cycles. Assessing this variability improves understanding of how Earth's system sensitivity to insolation evolves and provides insight into the factors driving the Messinian Salinity Crisis (MSC) and the Late Miocene Carbon Isotope Shift (LMCIS). New high-resolution benthic foraminiferal Cibicidoides mundulus δ18O and δ13C records from equatorial Pacific International Ocean Drilling Program Site U1338 are correlated to North Atlantic Ocean Drilling Program Site 982 to obtain a global perspective. Four long-term benthic δ18O variations are identified: the Tortonian-Messinian, Miocene-Pliocene, and Early-Pliocene Oxygen Isotope Lows (8-7, 5.9-4.9, and 4.8-3.5 Ma) and the Messinian Oxygen Isotope High (MOH; 7-5.9 Ma). Obliquity-paced variability dominates throughout, except during the MOH. Eleven new orbital-scale isotopic stages are identified between 7.4 and 7.1 Ma. Cryosphere and carbon cycle sensitivities, estimated from δ18O and δ13C variability, suggest a weak cryosphere-carbon cycle coupling. The MSC termination coincided with moderate cryosphere sensitivity and reduced global ice sheets. The LMCIS coincided with reduced carbon cycle sensitivity, suggesting a driving force independent of insolation changes. The response of the cryosphere and carbon cycle to obliquity forcing is established, defined as Earth System Response (ESR). Observations reveal that two late Miocene-early Pliocene climate states existed. The first is a prevailing dynamic state with moderate ESR and obliquity-driven Antarctic ice variations, associated with reduced global ice volumes. The second is a stable state, which occurred during the MOH, with reduced ESR and lower obliquity-driven variability, associated with expanded global ice volumes.

Lomonosov Ridge, Arctic Ocean: New MCS Data for the Definition of Targets for Scientific Drilling

NASA Astrophysics Data System (ADS)

Kristoffersen, Y.; Coakley, B.; Hall, J. K.

2001-12-01

The 1500 km long and 50-150 km wide Lomonosov Ridge rises more than 3000 m above the adjacent abyssal plains, separating the Mesozoic-aged Amerasian basin from the Cenozoic-Recent Eurasian basin. Multichannel seismic reflection data collected from icebreakers on four cruises together with swath bathymetry and high resolution chirp sonar data collected by nuclear submarines across the central ridge show a cap of hemipelagic drape (c. 450 m thick) on top of normal faulted and peneplained sedimentary sequences, the remnants of the Mesozoic Barents margin, which pre-dates the opening of the Eurasian Basin. A new multichannel seismic survey to augment the site survey data base for ODP proposal 533 was carried out on the Lomonosov Ridge under difficult ice conditions in late July 2001 from the Swedish icebreaker Oden. The primary objectives of ODP Proposal 533 are to obtain continuous paleoceanographic records for most of the Cenozoic from the hemipelagic sequence and to sample the underlying passive margin sequence below the regional unconformity, which would provide the first direct constraints on the early tectonic history of the ridge. Of particular interest is the extent of mass wasting along the ridge perimeter. This regional unconformity offers an opportunity for implementing a strategy of offset shallow drill holes to obtain a complete hemi-pelagic section as well as to penetrate the regional unconformity. The new data, which will, in conjunction with the existing MCS data base, provide the first 3-D control on the passive margin structures and overlying unconformity, will be presented.

Temperature Limit of the Deep Subseafloor Biosphere in the Nankai Trough Subduction Zone off Cape Muroto (IODP T-Limit Expedition 370)

NASA Astrophysics Data System (ADS)

Morono, Y.; Hauer, V. B.; Inagaki, F.; Kubo, Y.; Maeda, L.; Scientists, E.

2017-12-01

Expedition 370 of the International Ocean Discovery Program (IODP) aimed to explore the limits of life in the deep subseafloor biosphere at a location where elevated heat flow lets temperature increase with sediment depth beyond the known maximum of microbial life ( 120°C) at 1.2 km below the seafloor. Such conditions are met in the protothrust zone of the Nankai Trough off Cape Muroto, Japan, where Site C0023 was established in the vicinity of ODP Sites 808 and 1174 at a water depth of 4776 m using the drilling vessel DV Chikyu. Hole C0023A was cored down to a total depth of 1180 meters below seafloor, offshore sampling and research was combined with simultaneous shore-based investigations at the Kochi Core Center (KCC), and long-term temperature observations were started (Heuer et al., 2017). The primary scientific objectives of Expedition 370 are (a) to detect and investigate the presence or absence of life and biological processes at the biotic-abiotic transition of the deep subseafloor with unprecedented analytical sensitivity and precision; (b) to comprehensively study the factors that control biomass, activity, and diversity of microbial communities; and (c) to elucidate if continuous or episodic flow of fluids containing thermogenic and/or geogenic nutrients and energy substrates support subseafloor microbial communities in the Nankai Trough accretionary complex (Hinrichs et al., 2016). This contribution will highlight the scientific approach of our field-work and preliminary expedition results by shipboard and shorebased activities. Hinrichs K-U, Inagaki F, Heuer VB, Kinoshita M, Morono Y, Kubo Y (2016) Expedition 370 Scientific Prospectus: T-Limit of the Deep Biosphere off Muroto (T-Limit). International Ocean Discovery Program. http://dx.doi.org/10.14379/iodp.sp.370.2016 Heuer VB, Inagaki F, Morono Y, Kubo Y, Maeda L, the Expedition 370 Scientists (2017) Expedition 370 Preliminary Report: Temperature Limit of the Deep Biosphere off Muroto. International Ocean Discovery Program. http://dx.doi.org/10.14379/iodp.pr.370.2017

Santa Barbara Basin diatom and silicoflagellate response to global climate anomalies during the past 2200 years

USGS Publications Warehouse

Barron, J.A.; Bukry, D.; Field, D.

2010-01-01

Santa Barbara Basin (SBB) diatom and silicoflagellate assemblages are quantified from a box core record spanning AD 1940-2001 and an Ocean Drilling Program Hole 893A record from ???220 BC to AD 1880. The combined relative abundance of the diatoms Fragilariopsis doliolus and Nitzschia interrupteseriata from continuous two-year sampling intervals in the box core varies with sea surface temperature (SST), suggesting its utility in SST reconstruction. The assemblage data from the ODP 893A record indicate a broad interval of generally cooler SSTs between ???AD 800 and 1350, which corresponds to the Medieval Climate Anomaly (MCA), a period of generally warmer temperatures across other regions of the northern hemisphere. The assemblages also indicate an interval of generally warmer SSTs between ???AD 1400 and 1800, a period of otherwise global cooling referred to as the Little Ice Age (LIA). The changes in assemblages of diatoms and silicoflagellates support the hypothesis that the widespread droughts of the Medieval Climate Anomaly in the Western US were associated with cooler eastern North Pacific SST. The box core assemblages have higher percentages of tropical and subtropical compared to temperate and subpolar species than the ODP samples, reflecting a response of phytoplankton communities to an unusual 20th century warming. Pseudonitzschia australis, a diatom linked with domoic acid production, begins to become more common (>3% of the diatom assemblage) in the box core only after AD 1985, suggesting a link to anthropogenic activity. ?? 2008 Elsevier Ltd and INQUA.

Logic gate scanner focus control in high-volume manufacturing using scatterometry

NASA Astrophysics Data System (ADS)

Dare, Richard J.; Swain, Bryan; Laughery, Michael

2004-05-01

Tool matching and optimal process control are critical requirements for success in semiconductor manufacturing. It is imperative that a tool"s operating conditions are understood and controlled in order to create a process that is repeatable and produces devices within specifications. Likewise, it is important where possible to match multiple systems using some methodology, so that regardless of which tool is used the process remains in control. Agere Systems is currently using Timbre Technologies" Optical Digital Profilometry (ODP) scatterometry for controlling Nikon scanner focus at the most critical lithography layer; logic gate. By adjusting focus settings and verifying the resultant changes in resist profile shape using ODP, it becomes possible to actively control scanner focus to achieve a desired resist profile. Since many critical lithography processes are designed to produce slightly re-entrant resist profiles, this type of focus control is not possible via Critical Dimension Scanning Electron Microscopy (CDSEM) where reentrant profiles cannot be accurately determined. Additionally, the high throughput and non-destructive nature of this measurement technique saves both cycle time and wafer costs compared to cross-section SEM. By implementing an ODP daily process check and after any maintenance on a scanner, Agere successfully enabled focus drift control, i.e. making necessary focus or equipment changes in order to maintain a desired resist profile.

Influence of sealing post-treatments on the corrosion resistance of PEO coated AZ91 magnesium alloy

NASA Astrophysics Data System (ADS)

Mingo, B.; Arrabal, R.; Mohedano, M.; Llamazares, Y.; Matykina, E.; Yerokhin, A.; Pardo, A.

2018-03-01

The effect of three different post-treatments carried out on Plasma Electrolytic Oxidation (PEO) coated magnesium alloys are evaluated in terms of characterisation and corrosion resistance. Special interest is given to the role of a common additive (NaF) to the coating properties. The post-treatments are based on immersion sealing processes in aqueous solutions of inorganic salts (cerium and stannate based salts) and alcoholic solution of an organic acid (octodecylphosphate acid, ODP). Sealing mechanisms for each post-treatment are proposed. Cerium and stannate sealings are based on filling of the pores with the products of dissolution/precipitation reactions, while the ODP acid sealing is based on the formation of a thin layer of ODP over the coating through specific interactions between the polar part of the organic acid and the coating surface. All coatings are evaluated by salt fog test and analysed by electrochemical impedance spectroscopy. All sealings show a slight increase in the corrosion resistance of the coatings formed in the NaF-free electrolyte, but their positive influence is boosted in case of the coatings obtained in the NaF-containing electrolyte. This is related to the chemical and morphological changes at the coating surface induced by the presence of NaF in the electrolyte.

Characterization of integrated optical CD for process control

NASA Astrophysics Data System (ADS)

Yu, Jackie; Uchida, Junichi; van Dommelen, Youri; Carpaij, Rene; Cheng, Shaunee; Pollentier, Ivan; Viswanathan, Anita; Lane, Lawrence; Barry, Kelly A.; Jakatdar, Nickhil

2004-05-01

The accurate measurement of CD (critical dimension) and its application to inline process control are key challenges for high yield and OEE (overall equipment efficiency) in semiconductor production. CD-SEM metrology, although providing the resolution necessary for CD evaluation, suffers from the well-known effect of resist shrinkage, making accuracy and stability of the measurements an issue. For sub-100 nm in-line process control, where accuracy and stability as well as speed are required, CD-SEM metrology faces serious limitations. In contrast, scatterometry, using broadband optical spectra taken from grating structures, does not suffer from such limitations. This technology is non-destructive and, in addition to CD, provides profile information and film thickness in a single measurement. Using Timbre's Optical Digital Profililometry (ODP) technology, we characterized the Process Window, using a iODP101 integrated optical CD metrology into a TEL Clean Track at IMEC. We demonstrate the Optical CD's high sensitivity to process change and its insensitivity to measurement noise. We demonstrate the validity of ODP modeling by showing its accurate response to known process changes built into the evaluation and its excellent correlation to CD-SEM. We will further discuss the intrinsic Optical CD metrology factors that affect the tool precision, accuracy and its correlation to CD-SEM.

Three-dimensional modeling of HCFC-123 in the atmosphere: assessing its potential environmental impacts and rationale for continued use.

PubMed

Wuebbles, Donald J; Patten, Kenneth O

2009-05-01

HCFC-123 (C2HCl2F3) is used in large refrigeration systems and as a fire suppression agent blend. Like other hydrochlorofluorocarbons, production and consumption of HCFC-123 is limited under the Montreal Protocol on Substances that Deplete the Ozone Layer. The purpose of this study is to update the understanding of the current and projected impacts of HCFC-123 on stratospheric ozone and on climate and to discuss the potential environmental effects from continued use of this chemical for specific applications. For the first time, the Ozone Depletion Potential (ODP) of a HCFC is determined using a three-dimensional model (MOZART-3) of atmospheric physics and chemistry. All previous studies have relied on results from two-dimensional models. The derived HCFC-123 ODP of 0.0098 is smaller than previous values. Analysis of the projected uses and emissions of HCFC-123, assuming reasonable levels of projected growth and use in centrifugal chiller and fire suppressant applications, suggests an extremely small impact on the environment due to its short atmospheric lifetime, low ODP, low Global Warming Potential (GWP), and the small production and emission of its limited applications. The current contribution of HCFC-123 to stratospheric reactive chlorine is too small to be measurable.

Towards a robust and consistent middle Eocene astronomical timescale

NASA Astrophysics Data System (ADS)

Boulila, Slah; Vahlenkamp, Maximilian; De Vleeschouwer, David; Laskar, Jacques; Yamamoto, Yuhji; Pälike, Heiko; Kirtland Turner, Sandra; Sexton, Philip F.; Westerhold, Thomas; Röhl, Ursula

2018-03-01

Until now, the middle Eocene has remained a poorly constrained interval of efforts to produce an astrochronological timescale for the entire Cenozoic. This has given rise to a so-called "Eocene astronomical timescale gap" (Vandenberghe et al., 2012). A high-resolution astrochronological calibration for this interval has proven to be difficult to realize, mainly because carbonate-rich deep-marine sequences of this age are scarce. In this paper, we present records from middle Eocene carbonate-rich sequences from the North Atlantic Southeast Newfoundland Ridge (IODP Exp. 342, Sites U1408 and U1410), of which the cyclical sedimentary patterns allow for an orbital calibration of the geologic timescale between ∼38 and ∼48 Ma. These carbonate-rich cyclic sediments at Sites U1408 and U1410 were deposited as drift deposits and exhibit prominent lithological alternations (couplets) between greenish nannofossil-rich clay and white nannofossil ooze. The principal lithological couplet is driven by the obliquity of Earth's axial tilt, and the intensity of their expression is modulated by a cyclicity of about 173 kyr. This cyclicity corresponds to the interference of secular frequencies s3 and s6 (related to the precession of nodes of the Earth and Saturn, respectively). This 173-kyr obliquity amplitude modulation cycle is exceptionally well recorded in the XRF (X-ray fluorescence)-derived Ca/Fe ratio. In this work, we first demonstrate the stability of the (s3-s6) cycles using the latest astronomical solutions. Results show that this orbital component is stable back to at least 50 Ma, and can thus serve as a powerful geochronometer in the mid-Eocene portion of the Cenozoic timescale. We then exploit this potential by calibrating the geochronology of the recovered middle Eocene timescale between magnetic polarity Chrons C18n.1n and C21n. Comparison with previous timescales shows similarities, but also notable differences in durations of certain magnetic polarity chrons. We present a revision of previous astronomical timescales from the Equatorial and South Atlantic, to overcome the differences between different mid-Eocene astrochronologies. Using our new records from the North Atlantic, combined with existing records from the South Atlantic (ODP Site 1263 and Hole 702B) and Equatorial Atlantic (ODP Site 1260), we revise the durations of magnetic polarity Chrons C18n.1n to C21n, thereby arriving at a robust and self-consistent closure of the middle Eocene astronomical timescale gap.

Spatial and vertical gradients in the stable carbon isotope composition of Lower Circumpolar Deep Water over the last 900 thousand years

NASA Astrophysics Data System (ADS)

Williams, T.; Hillenbrand, C. D.; Piotrowski, A. M.; Smith, J.; Hodell, D. A.; Frederichs, T.; Allen, C. S.

2014-12-01

Changes in stable carbon isotopes (δ13C) recorded in benthic foraminiferal calcite reflect that of the dissolved inorganic carbon (DIC) of ambient seawater, and thus are used to reconstruct past changes in water mass mixing. Records of benthic foraminiferal δ13C from the Atlantic Ocean have revealed the development of a sharp vertical δ13C gradient between 2300-2500m water depth during successive glacial periods throughout the Late Quaternary, with extremely negative δ13C values recorded below this depth. It had been hypothesised that this gradient resulted from an increased stratification of water masses within the glacial Atlantic Ocean, and that these extreme δ13C values originated in the Southern Ocean. However the mechanisms behind the formation of this gradient and extreme δ13C depletion have remained unclear. This is in part due to the poor preservation of calcareous microfossils in the corrosive waters below 2500-3000m found in the Southern Ocean, which hampers our understanding of this key region. Here we present a unique new δ13C deep water record measured on benthic foraminifera (Cibicidoides spp.) from a sediment core recovered from 2100m water depth in the Amundsen Sea, south-eastern Pacific sector of the Southern Ocean. The site is bathed in Lower Circumpolar Deep Water (LCDW) today, and combined palaeomagnetic and oxygen isotope stratigraphy show that the sediments continuously span at least the last 890 ka. A comparison of this new δ13C data with other LCDW records from ODP Sites 1089/1090 in the South Atlantic and ODP Site 1123 in the Southwest Pacific demonstrate a clear spatial gradient in circum-Antarctic LCDW during glacial periods. The pool of extremely depleted glacial deep marine δ13C is restricted to the Atlantic Sector of the Southern Ocean, with increasingly positive δ13C values found in the Southwest Pacific and the south-eastern Pacific sector of the Southern Ocean. This implies that the δ13C depletion in the deep glacial Atlantic was sourced in the Atlantic sector of the Southern Ocean, and remained limited to this sector. This finding indicates either increased supply of relatively more positive δ13C deep waters or increased vertical mixing in the Indian and Pacific sectors of the glacial Southern Ocean.

Variable Seawater-Peridotite Interactions - First Insights From ODP Leg 209, MAR 15° N

NASA Astrophysics Data System (ADS)

Bach, W.; Garrido, C. J.; Harvey, J.; Paulick, H.; Rosner, M.; Odp Leg 193 Shipboard Science Party

2003-12-01

Serpentinization of peridotites at slow-spreading mid-ocean ridges has important consequences for the rheology of the oceanic lithosphere, geochemical budgets of the oceans, and microbial processes within, at, and above the seafloor. ODP Leg 209 recovered peridotites that show a remarkable variability of hydrothermal alteration reactions and intensities, including talc-tremolite alteration of pyroxenes associated with incipient serpentinization of olivine, complete alteration of peridotites to serpentine and magnetite followed by the destruction of magnetite and replacement of serpentine by talc, variable degrees of serpentine-brucite alteration, and replacement of brucite by iowaite. These rocks provide a unique opportunity to calibrate our observations against recent results from experimental/theoretical geochemical studies and further our understanding of serpentinization and its role in tectonic accretion and microbial colonization of oceanic lithosphere at slow and ultraslow spreading ridges. We propose that at temperatures above 250° C, pyroxenes react to form serpentine, talc, and tremolite, releasing Ca, Si, H2, and acidity to the reacting fluids that may cause rodingitization in adjacent gabbro bodies. Overall however, rodingites are rare, which may reflect the depleted nature of the mantle protoliths. In the absence of pyroxenes (in dunites) - or at temperatures below 250° C, where pyroxenes react very slowly - the fluids do not become enriched in Ca and Si and serpentine, magnetite, and brucite will form. Many serpentinites lack brucite, tremolite, and talc, because changes in fluid pH and silica activity of the interacting fluids, following the exhaustion of either olivine or pyroxene, caused reaction of these phases to serpentine. Extensive talc alteration of serpentinites and gabbros is usually observed at the intrusive contacts, but large-scale silica metasomatism (or Mg-loss) must be invoked to explain the overall abundance of talc at Site 1268. Significant pyrite/marcasite/hematite veining at Site 1268 indicates fairly oxidizing conditions consistent with the presence of sulfate in the interacting fluids. The first discovery of iowaite in mid-ocean ridge serpentinites (at Site 1272) and the abundant carbonate/Fe-oxyhydroxide alteration, locally extending down to 90 meters below seafloor, indicate that water-rock reactions continue at low temperatures and under strongly oxidizing conditions. Pore fluids from nontronite-bearing serpentine muds in fault gouges may provide information about the nature of these late-stage circulating fluids and potential microbial activity.

Implications of Smectite Subduction at the Costa Rican Convergent Margin

NASA Astrophysics Data System (ADS)

Cardace, D.; Morris, J. D.; Underwood, M. B.; Spinelli, G.

2003-12-01

Legs 205/170 of the Ocean Drilling Program (ODP) drilled a reference section on the incoming plate and sites at the toe of the sedimentary prism at the Costa Rican convergent margin. Complete sediment subduction has been documented, with the prism described by Leg 205/170 shipboard scientists as a paleoslump prism. Despite sediment subduction, Costa Rican arc lava geochemistry shows little sediment signal. Though subduction erosion has been posited as a mechanism for damping the geochemical sediment signal, this abstract addresses whether the clay content and distribution in the subducting pile can (a) play a role in localizing the decollement and (b) impact subduction of sediment to depth. X-ray diffraction (XRD) analyses of bulk sediment, with biogenic silica determinations, have been carried out for samples from the prism, through the decollement, to the underthrust sediments. Clay fractions have been isolated and silica studied for a subset of these samples. XRD peak areas of bulk samples were transformed into relative abundances via matrix singular value decomposition (Fisher and Underwood, 1995, Proc. ODP, Init. Repts., 156: 29-37), and adjusted following silica determination; volcanic ash has been neglected as a sedimentary component. Average relative weight percents of dominant minerals and biogenic silica (bSiO2) for prism toe units (Site 1040) are: P1A (silty clay, 74.8 m thick) 82 wt% clay, 5 wt% quartz, 13 wt% plagioclase, 0 wt% calcite; P1B (silty clay, 296.4 m thick) 82.1 wt% clay, 6.0 wt% quartz, 10.4 wt% plagioclase, 0 wt% calcite, 1.4 wt% bSiO2. Below the decollement, underthrust abundances are: U1A (clayey diatomite, 13.2 m thick) 82.7 wt% clay, 5.2 wt% quartz, 8.9 wt% plagioclase, 0 wt% calcite, 3.2 wt% bSiO2; U1B (clayey diatomite, 38.2 m thick) 80.7 wt% clay, 4.4 wt% quartz, 6.6 wt% plagioclase, 0 wt% calcite, 8.2 wt% bSiO2; U2 (silty claystone, 57.1 m thick) 84.8 wt% clay, 4.5 wt% quartz, 6.8 wt% plagioclase, 0 wt% calcite, 3.9 wt% bSiO2; U3A (siliceous nannofossil chalk, 18.1 m thick) 44.1 wt% clay, 2.0 wt% quartz, 5.6 wt% plagioclase, 31.8 wt% calcite, 16.5 wt% bSiO2; U3B (siliceous nannofossil chalk, 75.55 m thick) 1.9 wt% clay, 0 wt% quartz, 1.1 wt% plagioclase, 92.4 wt% calcite, 4.7 wt% bSiO2; and U3C (siliceous nannofossil chalk, 80.18 m thick) 6.6 wt% clay, 6.1 wt% quartz, 4.6 wt% plagioclase, 74.1 wt% calcite, 8.7 wt% bSiO2. XRD peak areas for clay fractions of prism samples above and in the decollement (Site 1254 ˜Site 1040, 300-370 mbsf) were transformed into relative weight percent data with Biscaye weighting factors. Smectites ranged from 77-93 wt%, illites ranged from 0-4 wt%, and kaolinites/chlorites ranged from 5-20 wt%. The maximum smectite value was obtained in the lower decollement. Bulk mineralogy data for sediments subducting at Costa Rica show that the prism and uppermost underthrust sediments are 80-93 wt% clay sized minerals. Clay mineralogy suggests that the smectite maximum occurs in the lower decollement and decreases dramatically below. Low biogenic silica abundances persist down core, emphasizing the importance of clays to the subducting section at Costa Rica.

THE IMPACT OF NEONATAL BREASTFEEDING ON GROWTH TRAJECTORIES OF YOUTH EXPOSED AND UNEXPOSED TO DIABETES IN UTERO: THE EPOCH STUDY

PubMed Central

Crume, T.L.; Ogden, L.G.; Mayer-Davis, E.J.; Hamman, R.F.; Norris, J.M.; Bischoff, K.J.; McDuffie, R.; Dabelea, D.

2011-01-01

Objective To evaluate the influence of breastfeeding on the body mass index (BMI) growth trajectory from birth through 13 years of age among offspring of diabetic pregnancies (ODP) and offspring of non-diabetic pregnancies (ONDP) participating in the EPOCH study. Subjects There were 94 ODP and 399 ONDP who had multiple BMI measures obtained from birth throughout childhood. A measure of breast milk-months was derived from maternal self-report to categorize breastfeeding status as adequate (≥6 breast milk-months) or low (<6 breast milk-months). Mixed linear effects models were constructed to assess the impact of breastfeeding on the BMI growth curves during infancy (birth to 27 months) and childhood (27 months to 13 years). Results ODP who were adequately breastfed had a slower BMI growth trajectory during childhood (p=0.047) and slower period-specific growth velocity with significant differences between 4 to 6 years of age (p=0.03) and 6 to 9 years of age (p=0.01) compared to ODP with low breastfeeding. A similar pattern was seen in the ONDP, with adequate breastfeeding associated with lower average BMI in infancy (p=0.03) and childhood (p=0.0002) and a slower growth trajectory in childhood (p=0.0002). Slower period-specific growth velocity was seen among the ONDP associated with adequate breastfeeding with significant differences between 12–26 months (p=0.02), 4–6 years (p=0.03), 6–9 years (p=0.0001) and 9–13 years of age (p<.0001). Conclusion Our study provides novel evidence that breastfeeding is associated with long-term effects on childhood BMI growth that extend beyond infancy into early and late childhood. Importantly, these effects are also present in the high-risk offspring, exposed to overnutrition during pregnancy. Breastfeeding in the early postnatal period may represent a critical opportunity to reduce the risk of childhood obesity. PMID:22290537

Decreased risk of cholangiocarcinogenesis following repeated cycles of Opisthorchis viverrini infection-praziquantel treatment: Magnetic Resonance Imaging (MRI) and histopathological study in a hamster model.

PubMed

Hanpanich, Petcharakorn; Laha, Thewarach; Sripa, Banchob; Mairiang, Eimorn; Sereerak, Piya; Upontain, Songkaid; Tangkawattana, Prasarn; Brindley, Paul J; Tangkawattana, Sirikachorn

2017-08-01

It has been suggested that repeated infection of Opisthorchis viverrini followed by repeated treatment with praziquantel (PZQ) increases risk of development of cholangiocarcinoma (CCA). Evidence for the prediction has accumulated based on findings of indirect approaches involving molecular changes and epidemiological trends. By contrast, here we directly monitored the impact of repeated liver fluke infection and treatment with PZQ on cholangiocarcinogenesis in a rodent model of human opisthorchiasis, using magnetic resonance imaging (MRI) and histopathology. Twenty five Syrian golden hamsters were assigned to five treatment groups: 1) infection with O. viverrini (OV group), 2) treatment with the carcinogen N-nitrosodimethylamine (NDMA) at 12.5ppm (DMN), 3) O. viverrini infection in tandem with NDMA (OD), 4) O. viverrini infection, NDMA, and treatment with PZQ (ODP), and 5) uninfected, untreated control. The repeated infections were established by intragastric inoculation of 50 metacercariae of O. viverrini to the OV, OD and ODP hamsters at weeks 0, 5 and 10. PZQ at 300mg/kg body weight was given to each hamster of the ODP group on weeks 4, 9 and 13 (four weeks after each infection). Imaging by MRI was undertaken on weeks 5, 10 and 14 (i.e. one week after each PZQ treatment). MRI revealed that the ODP hamsters did not develop CCA, whereas necropsy at week 40 revealed CCA in hamsters of the OD and DMN groups. Findings for histopathology and for proliferating cell nuclear antigen index conformed to the MRI findings. In overview, and notwithstanding that the immune response of individual hosts may play roles in cholangiocarcinogenesis, three cycles of the infection with O. viverrini followed treatment of the infection with PZQ did not increase the risk of bile duct cancer in this hamster model of liver fluke infection-induced CCA. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Marine sedimentary provenance evidence for massive discharges of icebergs from the Aurora and Wilkes sub-glacial basins

NASA Astrophysics Data System (ADS)

Pierce, E. L.; Williams, T.; van de Flierdt, T.; Hemming, S. R.; Brachfeld, S. A.; Goldstein, S. L.

2010-12-01

Understanding the evolution of the East Antarctic Ice Sheet (EAIS) is a fundamental goal in the field of paleoclimate today. Given the current and projected state of global warming, it is important to know how an ice sheet that holds over 50 m of sea-level has behaved under warmer conditions in the past. Despite the fact that over 98% of the East Antarctica continent is covered by thick (2.1 km on average) ice, the chronological characterization of glaciogenic detrital hornblende grains has been proven an excellent provenance tool in the investigation of the source areas for ice rafted detritus around Antarctica (Roy et al., 2007, Chem. Geo.). A circum-Antarctica core-top survey of Ar-Ar ages in hornblende grains demonstrates that East Antarctica can be simply divided into several sectors that correspond to modern ice divides and published geochronological evidence from sparse outcrops around the margins of the continent. Williams et al., (2010, EPSL) found evidence in ice rafted detritus layers in ODP Site 1165 from the Wilde drift off Prydz Bay for large discharges of icebergs from the Adélie and Wilkes Land coasts occurring during the late Miocene and early Pliocene. Sourcing from the Adélie and Wilkes Land coasts requires iceberg transport more than 1500 km around the Antarctic perimeter, and this is therefore evidence for massive discharges of icebergs from these sectors. In the Aurora and Wilkes Basins in these sectors, the ice sheet is grounded well below sea level, and is therefore thought to be potentially unstable under warmer conditions. Such long distant transport of sediments with distinctive sources is reminiscent of Heinrich Events in the North Atlantic. A model often invoked as the cause of these events is the collapse and retreat of ice-streams, which leads to massive discharges of icebergs, laden with sediment, into the ocean. The importance of this interpretation, if true, has led us to make more detailed studies of Quaternary sediments from the Adélie and Wilkes Land coasts as well as glaciogenic sediments throughout the Cenozoic in Prydz Bay. We will present Ar-Ar ages of detrital hornblende and biotite grains (>150 µm), as well as epsilon-Nd values measured on the terrigenous fine fraction (<63 µm), from 9 marine sediment cores along the Adélie and Wilkes Land coasts of East Antarctica (95° to 165°E), and compare them and proximal Prydz Bay data with IRD layers in ODP Site 1165. We have also compared the Ar-Ar biotite age populations from the same IRD layers in ODP site 1165 that Williams et al., (2010, EPSL) examined to explore the use of Ar-Ar biotite ages as a tracer of IRD; given the high K content in biotite, it may be possible to use the 63-150 µm fraction for provenance studies which may be particularly useful for tracing sources of IRD into the Southern Ocean where IRD abundances are low and thus grain sizes tend to be finer. The combined application of these tracers will allow interpretation of the average crust formation age of the sources, as well as provide information on major tectonothermal pulses and cooling through approximately 300°C.

Evolution of the Northern Nicaragua Rise during the Oligocene Miocene: Drowning by environmental factors

NASA Astrophysics Data System (ADS)

Mutti, Maria; Droxler, André W.; Cunningham, Andrew D.

2005-04-01

Possible causes to explain platform drowning have been hotly debated by carbonate sedimentologists for more than a decade now. In this paper, we present multiple evidence to explain the drowning of a carbonate megabank that covered most of the modern Northern Nicaragua Rise (NNR) during an interval spanning from late Oligocene to early Miocene by the interaction of several environmental factors. The recovery during ODP Leg 165 of late Oligocene to middle Miocene sedimentary sequences in the sub-seafloor of the modern channels and basin, Pedro Channel and Walton Basin, respectively, that dissect the NNR (Site 1000) and south of the rise in the Colombian Basin (Site 999), combined with information from dredged rock samples, allows us to explore in more detail the timing and possible mechanisms responsible for the drowning of the megabank and its relationship to Miocene climate change. The modern system of isolated banks and shelves dissected by a series of intervening seaways and basins on the NNR has evolved from a continuous, shallow-water carbonate “megabank” that extended from the Honduras/Nicaraguan mainland to the modern island of Jamaica. Available information suggests that this megabank broke apart and partially drowned in the late part of the late Oligocene at around 27 Ma and finally foundered during the late early Miocene around 20 Ma, resulting in limited neritic coral growth in the areas where the modern isolated carbonate banks and shelves are occurring today. Available information also suggests that the southern and central parts of Pedro Channel were already a deep-water area before the major episode of platform drowning, and its formation predates the initiation of the Caribbean Current. However, after the partial drowning of the megabank, the channel has become a major pathway for the Caribbean Current. Stratigraphic units identified in deep-water carbonates sampled at ODP Sites 999 and 1000 help to constrain the environmental setting leading to the drowning of the banks. Changes in lithology and mass accumulation rates of both the carbonate and non-carbonate fraction parallel stable isotope shifts and likely indicate regional changes in climate and circulation during the late Oligocene middle Miocene interval. Carbonate mass accumulation rates (MARs) at Site 999 suggest increased regional productivity during the early Miocene. Terrigenous MARs at both Sites 999 and 1000 show a general increase from the Burdigalian through the Serravallian. The temporal association among episodes of neritic platform deposition, followed by increased productivity as identified by higher carbonate MARs and positive excursion in carbon isotopes, suggests that oceanographic changes such as local upwelling and nutrification have led to the partial drowning of the NNR “megabank”.

Evidence for Water-Mass Changes on the Tasmanian Slope during the Early Miocene (19-16.5 Ma): Stable Isotope and Mg/Ca Records from ODP Leg 189 Site 1168

NASA Astrophysics Data System (ADS)

Pekar, S. F.; Marchitto, T. M.; Lynch-Steiglitz, J.

2002-12-01

High-resolution stable isotope (4-10 k.y. resolution) and moderately low-resolution Mg/Ca ratio records were constructed for the late early Miocene (19-16.5 Ma) from ODP Leg 189 Site 1168, located on the southwest slope of Tasmania. These records evaluated paleoceanographic changes that took place during isotopic excursions Mi1b (18.2-17.8 Ma) and Mi2 (16.5 Ma), and the First Climatic Optimum (17.7-16.7 Ma), a time of increased global warmth. Evidence exists that supports the idea for the development of warm saline deep waters (WSDW) originating from the eastern end of the Tethys Sea during the early Miocene. However, questions remain regarding the extent and strength of the WSDW and the possible role it played in the warming that took place during the First Climatic Optimum. Site 1168 is ideally located on the lower slope (estimates place it in lower bathyal waters during the early Miocene) to evaluate the potential penetration of WSDW and into the Southern Ocean. Large fluctuations in the isotope and Mg/Ca ratio records from Site 1168 suggest changes in the water masses that bathed the Tasmanian slope during the early Miocene. Temperature estimates based on Mg/Ca ratios contain a surprisingly high range, from 4° to 10° C. Low temperatures (4°-6° C) are associated with high carbon isotope values (>1.4‰ ) and are interpreted represent Southern Component Waters (SCW). The high carbon isotope values also suggest a proximal source for SCW. High water temperatures (7°-10° C) indicate a warm-water mass and are interpreted to be due to the penetration of WSDW into this area, replacing SCW at various times. Large high-frequency isotopic excursions (low oxygen and carbon isotope values) occurred between 18.7 and 18.4 Ma and were originally thought to be due to either localized effects (e.g., disassociation of hydrates) or possible diagensis. However, a recently published high-resolution isotopic record from the Southern Ocean (Site 1090) also contains large isotopic excursions (e.g., >1‰ decrease in oxygen isotope values) at this time, suggesting that these events may not due to diagensis but may be transient global events. We interpret that the changes observed in the isotopic and Mg/Ca ratio records are the result of both changes in the cryosphere and water-mass changes in the vicinity of Tasmania, the latter being due to the penetration of WSDW into the Southern Ocean.

The End of the Penultimate Interglacial Recorded in Santa Barbara Basin, California

NASA Astrophysics Data System (ADS)

Cannariato, K. G.; Kennett, J. P.

2005-12-01

The marine sediments accumulating in the Santa Barbara Basin, located on the southern California margin, represent a remarkable climate archive. The high sediment accumulation rate, location at the intersection of the cool California Current and warm Countercurrent, and other factors affecting the basin have combined to make the paleoclimate records generated from these sediments highly resolved and very sensitive to global climate change. Because of the effort by Dr. James Kennett over a decade ago to persuade the Ocean Drilling Program to core the basin, the paleoceanographic community has been able to produce some of the most detailed records of Northern Hemisphere climate change over most of the last two glacial-interglacial cycles rivaling those of the Greenland ice cores. Here we present high-resolution planktic and benthic oxygen isotope records from that Santa Barbara Basin core, ODP Site 893, covering the penultimate interglacial and the beginning of the last glacial (MIS 5e to 5d transition). The results indicate that the California Current system exhibited millennial and centennial variability during the penultimate interglacial similar to the early-middle Holocene. The magnitude of this millennial variability increased dramatically and quickly during the transition from MIS 5e to 5d. These millennial-scale oscillations appear to be correlated to those recognized in the North Atlantic region. The implications of this variability will be discussed.

Evidence for a heavily glaciated Antarctica during the late Oligocene "warming" (27.8-24.5 Ma): Stable isotope records from ODP Site 690

NASA Astrophysics Data System (ADS)

Hauptvogel, D. W.; Pekar, S. F.; Pincay, V.

2017-04-01

High δ18O values (> 3.0‰) from a 9 kyr resolution benthic foraminiferal stable isotope record from the Ocean Drilling Program hole 690B located on the Maud Rise, Antarctica, indicate a heavily glaciated Antarctic continent during late Oligocene (27.8-24.5 Ma). Values ranging 2.5-3.0‰ during interglacial periods and 3.0-3.6‰ during glacial intervals are consistent with an ice sheet near or larger than modern size. In addition, this record does not exhibit the long-term late Oligocene warming trend seen in records from low-latitude drill sites. Oxygen isotope values from 26.0 to 24.5 Ma are comparable (ranging between 2.5 and 3.3‰) to values that preceded the δ18O event Oi2b at 26.7 Ma, indicating no significant glacial collapse occurred during the late Oligocene. A gradient between ocean basins during the Oligocene has already been linked to the development of a modern, multilayered ocean and worked to bathe the low latitude to midlatitude, deep-sea records with a warmer water mass. We suggest that this masked the significant Antarctic glaciation in low-latitude paleoceanographic records. Additionally, we propose a resolution for conflicting lines of evidence from some Antarctic proximal records suggesting significant glaciation and others suggesting reduced glaciation during the late Oligocene by allowing a modern-sized ice sheet to grow on an Antarctic continent as more land surface area existed above sea level during this time. This could allow at least some portions of the Antarctic coastline to remain ice-free during glacial minima while still maintaining modern or near-modern ice volume.

Changes in Nannoplankton Assemblages during the recovery of the Paleocene Eocene Thermal Maximum (PETM)

NASA Astrophysics Data System (ADS)

Grey, J. A.; Bralower, T. J.; Self-Trail, J. M.

2016-12-01

The recovery interval of the Paleocene Eocene Thermal Maximum (PETM) presents an opportunity to examine how organisms adapt to environmental change after a rapid global warming event. Calcareous nannoplankton survived the PETM, but we lack an understanding of how long it took for assemblages to adapt to a changing climate and the millennial-scale changes in their ecology. Here, we present the first high-resolution record of nannoplankton community change during the PETM recovery using a global data set (United States Geological Survey (USGS) Wilson Lake core, USGS Cam-Dor core, Ocean Drilling Program (ODP) Sites 690, 1265, and 1209) to assess millennial-scale assemblage change across space and time. Preliminary multivariate analyses on assemblage changes at Wilson Lake demonstrate that within 20,000 years after the onset, the structure of nannoplankton communities shifts from an assemblage dominated by warm eutrophic specialists to one dominated by eutrophic low salinity specialists. In the late recovery, ubiquitous taxa dominate assemblages, suggesting that the shelf environment became favorable for generalists. The latest part of the recovery is marked by a slight increase in oligotrophic specialists, indicating that the shelf became less eutrophic into the early Eocene. Overall, these analyses suggest that assemblages changed rapidly in response to cooling and changing ocean circulation during the early recovery of the PETM. Future analyses will build on these data by comparing assemblage change from other PETM coastal and open ocean sites. These analyses will help us better understand the spatial and temporal changes of nannoplankton communities on a global scale, lessons that can inform how nannoplankton will respond to future climate change.

Rapid directional changes associated with a 6.5 kyr-long Blake geomagnetic excursion at the Blake-Bahama Outer Ridge

NASA Astrophysics Data System (ADS)

Bourne, Mark; Mac Niocaill, Conall; Thomas, Alex L.; Knudsen, Mads Faurschou; Henderson, Gideon M.

2012-06-01

Geomagnetic excursions are recognized as intrinsic features of the Earth's magnetic field. High-resolution records of field behaviour, captured in marine sedimentary cores, present an opportunity to determine the temporal and geometric character of the field during geomagnetic excursions and provide constraints on the mechanisms producing field variability. We present here the highest resolution record yet published of the Blake geomagnetic excursion (∼125 ka) measured in three cores from Ocean Drilling Program (ODP) Site 1062 on the Blake-Bahama Outer Ridge. The Blake excursion has a controversial structure and timing but these cores have a sufficiently high sedimentation rate (∼10 cm ka-1) to allow detailed reconstruction of the field behaviour at this site during the excursion. Palaeomagnetic measurements of the cores reveal rapid transitions (<500 yr) between the contemporary stable normal polarity and a completely reversed state of long duration which spans a stratigraphic interval of 0.7 m. We determine the duration of the reversed state during the Blake excursion using oxygen isotope stratigraphy, combined with 230Th excess measurements to assess variations in the sedimentation rates through the sections of interest. This provides an age and duration for the Blake excursion with greater accuracy and with constrained uncertainty. We date the directional excursion as falling between 129 and 122 ka with a duration for the deviation of 6.5±1.3 kyr. The long duration of this interval and the fully reversed field suggest the existence of a pseudo-stable, reversed dipole field component during the excursion and challenge the idea that excursions are always of short duration.

High-resolution climatic evolution of coastal northern California during the past 16,000 years

USGS Publications Warehouse

Barron, J.A.; Heusser, L.; Herbert, T.; Lyle, M.

2003-01-01

Holocene and latest Pleistocene oceanographic conditions and the coastal climate of northern California have varied greatly, based upon high-resolution studies (ca. every 100 years) of diatoms, alkenones, pollen, CaCO3%, and total organic carbon at Ocean Drilling Program (ODP) Site 1019 (41.682??N, 124.930??W, 980 m water depth . Marine climate proxies (alkenone sea surface temperatures [SSTs] and CaCO3%) behaved remarkably like the Greenland Ice Sheet Project (GISP)-2 oxygen isotope record during the B??lling-Allerod, Younger Dryas (YD), and early part of the Holocene. During the YD, alkenone SSTs decreased by >3??C below mean B??lling-Allerod and Holocene SSTs. The early Holocene (ca. 11.6 to 8.2 ka) was a time of generally warm conditions and moderate CaCO3 content (generally >4%). The middle part of the Holocene (ca. 8.2 to 3.2 ka) was marked by alkenone SSTs that were consistently 1-2??C cooler than either the earlier or later parts of the Holocene, by greatly reduced numbers of the gyre-diatom Pseudoeunotia doliolus (<10%), and by a permanent drop in CaCO3% to <3%. Starting at ca. 5.2 ka, coastal redwood and alder began a steady rise, arguing for increasing effective moisture and the development of the north coast temperate rain forest. At ca. 3.2 ka, a permanent ca. 1??C increase in alkenone SST and a threefold increase in P. doliolus signaled a warming of fall and winter SSTs. Intensified (higher amplitude and more frequent) cycles of pine pollen alternating with increased alder and redwood pollen are evidence that rapid changes in effective moisture and seasonal temperature (enhanced El Nin??o-Southern Oscillation [ENSO] cycles) have characterized the Site 1019 record since about 3.5 ka.

New Magnetic and 10Be/9Be results from ODP site 851 (East Equatorial Pacific)

NASA Astrophysics Data System (ADS)

Valet, J. P.; Savranskaia, T.; Anojh, T.; Meynadier, L.; Thouveny, N.; Gacem, L.; L2NC, A. T.; Bassinot, F. C.; Simon, Q.

2017-12-01

The paleomagnetic record from ODP site 851 was the first long data of relative paleointensity that attempted to describe 4 Ma of geomagnetic variations. Among other features, it was characterized by an asymmetrical saw-tooth pattern of the intensity changes across reversals. The upper part of the record (0 to 1.1 Ma) was documented by stepwise alternating field (af) demagnetization of U-channels, while the deeper part could not be sampled by U-channels and instead combined shipboard measurements and stepwise demagnetized single samples within specific intervals. Thermal demagnetization was also conducted within specific intervals to assess the absence of viscous component. We performed a new detailed study using U-channels and single samples that were taken along a continuous splice section that covers the upper 80 meters of sediment. Stepwise demagnetization of the natural magnetization and of the anhysteretic magnetization were carried out for all samples and U-channels in order to improve the resolution and the reliability of relative paleointensity for the older part of the record. The new results improve the detailed magnetostratigraphy that was formerly established and provide additional details to the paleointensity results. In parallel, 10Be/9Be measurements were carried out at the same levels as the magnetic measurements to test further the controversial asymmetrical pattern of relative paleointensity. Unfortunately, the 10Be/9Be results did not provide any consistent signal. This failure most likely results from high carbonate concentration (about 85%) that yields poor adsorption of beryllium by the sediment particles and therefore generates large fluctuations. The reliability of the paleointensity record is linked to downcore homogeneity of the sediment that is characterized by little variability of carbonate content and therefore little changes in the magnetization response to the field. Summarizing poor clay content appears to be a favorable situation for relative paleointensity, while 10Be studies would benefit from the presence of clay-rich sediments. More generally, this lithological dependence should help understand differences between amplitudes and patterns of relative paleointensity and beryllium records.

Alkalic marine tephra layers at ODP Site 1241 - Major explosive eruptions from an oceanic volcano in a pre-shield stage?

NASA Astrophysics Data System (ADS)

Schindlbeck, J. C.; Kutterolf, S.; Freundt, A.; Andrews, G. D. M.; Wang, K.-L.; Völker, D.; Werner, R.; Frische, M.; Hoernle, K.

2016-12-01

We report a series of fourteen marine tephra layers that are the products of large explosive eruptions of Subplinian to Plinian intensities and magnitudes (VEI > 4) from Cocos Island, Costa Rica. Cocos Island is a volcanic island in the eastern Central Pacific Ocean 500 km offshore Costa Rica, and is situated on the northwestern flank of the aseismic Cocos Ridge. Geochemical fingerprinting of Pleistocene ( 2.4-1.4 Ma) marine tephra layers from Ocean Drilling Project (ODP) Leg 202 Site 1241 using major and trace element compositions of volcanic glass shards demonstrates unequivocally their origin from Cocos Island rather than the Galápagos Archipelago or the Central American Volcanic Arc (CAVA). Cocos Island and the adjacent seamounts of the Cocos Island Province have alkalic compositions and formed on young (≤ 3 Ma) oceanic crust from an extinct spreading ridge bounded by a transform fault against the older and thicker crust of the aseismic Cocos Ridge. Cocos Island has six times the average volume of the adjacent seamounts although all appear to have formed during the 3-1.4 Ma time period. Cocos Island lies closest to the transform fault and we explain its excessive growth by melts rising from garnet-bearing mantle being deflected from the thick Cocos Ridge lithosphere toward the thinner lithosphere on the other side of the transform, thus enlarging the melt catchment area for Cocos Island compared to the seamounts farther away from the transform. This special setting favored growth above sea level and subaerial explosive eruptions even though the absence of appropriate compositions suggests that the entirely alkalic Cocos Island (and seamounts) never evolved through the productive tholeiitic shield stage typical of other Pacific Ocean islands, possibly because melt production rates remained too small. Conditions of magma generation and ascent resembled Hawaiian pre-shield volcanoes but persisted for much longer (< 1 m.y.) and formed evolved, trachytic magmas. Therefore Cocos Island may be a unique example for a volcanic ocean island that did not pass through the typical growth stages.

A 3 million year index for North African humidity/aridity and the implication of potential pan-African Humid periods

NASA Astrophysics Data System (ADS)

Grant, Katharine M.; Rohling, Eelco J.; Westerhold, Thomas; Zabel, Matthias; Heslop, David; Konijnendijk, Tiuri; Lourens, Lucas

2017-09-01

Mediterranean sediments are valuable archives of both African monsoon variability and higher-latitude climate processes, and can also be used to provide an environmental context for early human migrations and settlements. However, the long history of Mediterranean palaeoclimate studies largely pre-dates the advent of widespread x-ray fluorescence (XRF) core-scanning, so there are few continuous and high-resolution geochemical records from this key region that extend beyond the last glacial cycle. Here we present XRF core-scanning results for ODP Site 967 (Eastern Mediterranean) that have been fully-calibrated into element concentrations spanning the last 3 million years (My). Comparison with independent geochemical data from conventional XRF highlights disparities for certain element/element ratios, thus suggesting the need for caution when taking ratios of scanning XRF data. Principal component analysis of the calibrated XRF dataset reveals two dominant components: detrital inputs (PC1) and a 'sapropel' (≈monsoon run-off) signal (PC2), which we use to establish a new orbitally-tuned chronology. We observe inverse covariation between PC2 and a previously published aeolian dust record from ODP Site 967 (Larrasoaña et al., 2003), and combine these records to produce a composite index of humidity and aridity for the wider North African region over the past 3 My. We propose that by combining run-off and dust signals in a single metric, our index captures the effects of both strengthening/northward migration (increased run-off) and weakening/southward retreat (increased dust) of the North African monsoon. Comparison of the index with published records of Northwest and East African palaeohumidity suggests that it tracks the timing of ;Green Sahara Periods; throughout the Plio-Pleistocene, and that at least 30 of these intervals coincided with increased humidity across East Africa. We tentatively suggest that these specific episodes may be termed ;pan-African Humid Periods;, as a means to highlight large-scale climate trends and to provide an environmental framework for palaeo-anthropological research.

"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.

Poroelastic Parameters of Peru Margin Sediments: Implications for Flow and Transport at Multiple Scales in the Marine Biosphere

NASA Astrophysics Data System (ADS)

Gettemy, G. L.; Cikoski, C.; Tobin, H. J.

2004-12-01

As part of a broader investigation of the deep marine subsurface environment, the first biosphere-focused drilling expedition, Leg 201, of the Ocean Drilling Program (ODP) occupied five unique sites in the Peru Margin (in a 1200 km2 region centered at 10 S, 80E). These sites represent the entire range of shallow biogeological conditions associated with this convergent margin:deep-water, mixed clay-pelagic sediments ocean-ward of the trench; slope-apron and prism toe sediments at the deformation front; and several distinct lithostratigraphic sequences on the continental shelf. Microbial enumeration and pore-water geochemistry results show that each particular site is both consistent and unique--consistent in terms of general biotic quantity and activity as predicted by energy flux and redox potential given the depositional environment and sedimentary record, but unique at key biogeological boundaries such as lithologic and/or physical property interfaces. This research addresses questions related to our understanding of how and why these boundaries form by looking at poroelastic and hydrologic parameters measured at multiple scales, from sub-millimeter to several centimeters. The issue of measurement scale, especially in regard to permeability and diffusivity characterization, is vital to interpreting observations of biologically-mediated diagenetic fronts (e.g., dolomitic lenses, depth- or time-varying barite fronts). These parameters are derived from (i) hydrologic and wave propagation experiments, (ii) SEM images, and (iii) shipboard split-core measurements, and structured in a modified Biot poroelasticity framework. This approach also allows quantification of the local heterogeneity of these parameters at the scale applicable to (and controlled by) microbial life; these results can then be used to formulate predictive models of the impact of biogeochemical processes. Ultimately, these models could then be used in interpretation of new remote-sensed data (e.g., from borehole tools, high-frequency backscatter devices), a fundamental challenge for all types of biospheric imaging everywhere.

The Third Dimension of an Active Back-arc Hydrothermal System: ODP Leg 193 at PACMANUS

NASA Astrophysics Data System (ADS)

Binns, R.; Barriga, F.; Miller, D.

2001-12-01

This first sub-seafloor examination of an active hydrothermal system hosted by felsic volcanics, at a convergent margin, obtained drill core from a high-T "smoker" site (penetrated to sim200 mbsf) and a low-T site of diffuse venting (~400mbsf). We aimed to delineate the lateral and vertical variability in mineralisation and alteration patterns, so as to understand links between volcanological, structural and hydrothermal phenomena and the sources of fluids, and to establish the nature and extent of microbial activity within the system. Technological breakthroughs included deployment of a new hard-rock re-entry system, and direct comparison in a hardrock environment of structural images obtained by wireline methods and logging-while-drilling. The PACMANUS hydrothermal site, at the 1700m-deep crest of a 500m-high layered sequence of dacitic lavas, is notable for baritic massive sulfide chimneys rich in Cu, Zn, Au and Ag. Below an extensive cap 5-40m thick of fresh dacite-rhyodacite, we found unexpectedly pervasive hydrothermal alteration of vesicular and flow-banded precursors, accompanied by variably intense fracturing and anhydrite-pyrite veining. Within what appears one major hydrothermal event affecting the entire drilled sequence, there is much overprinting and repetition of distinctly allochemical argillaceous (illite-chlorite), acid-sulfate (pyrophyllite-anhydrite) and siliceous assemblages. The alteration profiles include a transition from metastable cristobalite to quartz at depth, and are similar under low-T and high-T vent sites but are vertically condensed in a manner suggesting higher thermal gradients beneath the latter. The altered rocks are surprisingly porous (average 25%). Retention of intergranular pore spaces and open vesicles at depth implies elevated hydrothermal pressures, whereas evidence from fluid inclusions and hydrothermal brecciation denotes local or sporadic phase separation. A maximum measured temperature of 313 degC measured 8 days after drilling (360 mbsf at the diffuse venting site), if indicative of thermal gradient, suggests the presence of a very shallow ( ~1.5 km below seafloor) magmatic heat source. While isotopic characteristics of anhydrite suggest an irregularly varying component of magmatic fluid, the abundance of this mineral implies a substantial role for circulating seawater within the subsurface hydrothermal system. Other than the near-ubiquitous, fine grained disseminated pyrite in altered rocks, we found little sulfide mineralisation. Pyritic vein networks and breccias are extensive in the rapidly penetrated, but poorly recovered, interval down to 120 mbsf within our "high-T end-member" hole spudded on a mound surmounted by active (280 degC) chimneys. Anhydrite and open cavities possibly dominate this interval, from which a possible example of subhalative semi-massive sulfide containing chalcopyrite and some sphalerite was recovered near 30 mbsf. At the low-T and high-T vent sites respectively, anaerobic microbes were recorded by direct counting at depths down to 99 and 78 mbsf, and in 90 degC cultivation experiments at 69-107 and 99-129 mbsf. >http://www-odp.tamu.edu/publications/prelim/193

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.

Contribution of slab melting to magmatism at the active rifts zone in the middle of the Izu-Bonin arc

NASA Astrophysics Data System (ADS)

Hirai, Y.; Okamura, S.; Sakamoto, I.; Shinjo, R.; Wada, K.; Yoshida, T.

2016-12-01

The active rifts zone lies just behind the Quaternary volcanic front in the middle of the Izu-Bonin arc. Volcanism at the active rifts zone has been active since ca. 2 Ma, and late Quaternary basaltic lavas (< 0.1 Ma) and hydrothermal activity occur along the central axis of the rifts (Taylor, 1992; Ishizuka et al., 2003). In this paper we present new Sr, Nd, and Hf isotope and trace element data for the basalts erupted in the active rifts zone, including the Aogashima, Myojin and Sumisu rifts. Two geochemical groups can be identified within the active rift basalts: High-Zr basalts (HZB) and Low-Zr basalts (LZB). In the case of the Sumisu rift, the HZB exhibits higher in K2O, Na2O, Y, Zr and Ni, and also has higher Ce/Yb and Zr/Y, lower Ba/Th than the LZB. Depletion of Zr-Hf in the N-MORB spidergram characterizes the LZB from the Aogashima, Myojin and Sumisu rifts. The 176Hf/177Hf ratios are slightly lower in the HZB than in the LZB, decoupling of 176Hf/177Hf ratios and 143Nd/144Nd ratios. Estimated primary magma compositions suggest that primary magma segregation for the HZB occurred at depths less than 70 km ( 2 GPa), whereas the LZB more than 70 km (2 3 GPa). ODP Leg126 site 788, 790, and 791 reached the basaltic basement of the Sumisu rift (Gill et al., 1992). The geochemical data and stratigraphic relations of the basement indicate that the HZB is younger than the LZB. Geochemical modelling demonstrates that slab-derived melt mixed with mantle wedge produces the observed isotopic and trace elemental characteristics. The LZB volcanism at the early stage of the back-arc rifting is best explained by a partial melting of subducted slab saturated with trace quantities of zircon under low-temperature conditions in the mantle wedge. On the other hand, the HZB requires a partial melt of subducted slab accompanied by full dissolution of zircon under high-temperature conditions in the mantle wedge, which could have been caused by hot asthenospheric injection during the syn stage of the back-arc rifting. referencesGill et al. (1992) Proc. ODP, Sci. Result, 126, 383-403. Ishizuka et al. (2003) Geol. Soc. Spec. Publ., 219, 187-205. Taylor (1992) Proc. ODP, Sci. Result, 126, 627-651.

Systems Harmonization and Convergence - the GIGAS Approach

NASA Astrophysics Data System (ADS)

Marchetti, P. G.; Biancalana, A.; Coene, Y.; Uslander, T.

2009-04-01

0.1 Background The GIGAS1 Support Action promotes the coherent and interoperable development of the GMES, INSPIRE and GEOSS initiatives through their concerted adoption of standards, protocols, and open architectures. 0.2 Preparing for Coordinated Data Access The GMES Coordinated Data Access System is under design and implementation2. This objective has motivated the definition of the interoperability standards between the contributing missions. The following elements have been addressed with associated papers submitted to OGC: The EO Product Metadata has been based on the OGC Geographic Markup Language, addressing sensor characteristics for optical, radar and atmospheric products. Collection and service discovery: an ISO extension package for CSW ebRim has been proposed. Catalogue Service (CSW): an Earth Observation extension package of the CSW ebRim has been proposed. Feasibility Analysis and Order: an Order interface control document and an Earth Observation profile of the Sensor Planning Service have been proposed. Online Data Access: an Earth Observation profile of the Web Map Services (WMS) for visualization and evaluation purposes has been proposed. Identity (user) management: the objective in the long term is to allow for a single sign-on to the Coordinated Data Access system by users registered in the various Earth Observation ground segments by providing a federated identity across participating ground segments, exploiting OASIS standards. 0.3 The GIGAS proposed harmonization approach The approach proposed by GIGAS is based on three elements: Technology watch Comparative analysis Shaping of initiatives and standards This paper concentrates on the methodology for technology watch and comparative analysis. The complexity of the GIGAS scenario involving huge systems (i.e. GEOSS, INSPIRE, GMES etc.) entails the interaction with different heterogeneous partners, each with a specific competence, expertise and know-how. 0.3.1 Technology watch The methodology proposed is based on an RM-ODP based study supported by interoperability use cases and scenarios used to derive requirements. GIGAS will monitor the INSPIRE, GMES and GEOSS evolution and analyze the requirements, the standards, the services and the architecture, the models, the processes and the consensus mechanisms with the same elements of the other systems under analysis. activities in the fields of standard development that are part of the three initiatives. This task will provide the basis for how these three initiatives will strategically support consensus and efficient standards development going forward. architecture, specifications, innovative concepts and software developments of past or ongoing FP6/FP7 research topics. The use of an RM-ODP approach is selected as: most of the architectural approaches to be compared are based on RM-ODP, it supports distributed processing, it aims at fostering interoperability across heterogeneous systems, it tries to hide distribution to systems developers. However, as most of the systems to be considered have the characteristic of a loosely-coupled network of systems and services instead of a "distributed processing system based on interacting objects", the RM-ODP concepts are tailored for the GIGAS needs. The usage of RM-ODP for GIGAS Requirements and Technology Watch is two-fold: Architectural analysis: It is performed for all projects and initiatives. Its purpose is to identify possibilities but also major obstacles for interoperability. Furthermore, it identifies the major use cases to be analysed in more detail. Use Case Implementation Analysis: It is used to describe how selected use cases of the projects and initiatives are implemented in the different architectures. Its purpose is to identify technological gaps and concrete problems of interoperability. It is performed only for selected use cases. The output of the Technology Watch is an RM-ODP based report containing parallel analysis on the same aspects on the three initiatives integrated by analysis of relevant FP6-FP7 projects and standardization activities. 0.3.2 Comparative Analysis Based on the outcomes of the previous monitoring tasks, GIGAS undertakes a comparative analysis on solutions, requirements, architecture, models, processes and consensus mechanisms used by INSPIRE, GMES and GEOSS, taking into account the inputs from the monitoring of FP6/FP7 research projects and the ongoing standardization activities. Initiative Contact Points will insure that the overall policy framework and schedules for each of the three initiatives will be factored in. The result of the Comparative Analysis includes: A list of recommendations to GEOSS, INSPIRE and GMES to be expanded and processed in depth in the following shaping phase The identification of technological gaps to be explored in the following shaping phase. Guidelines and objectives for the architectural approach within GIGAS Analysis on the schedules of the three initiatives and on the FP6/FP7 programs and standardization activities, with identification of key milestones or intervention points.

Glacial-Interglacial Variability of Nd isotopes in the South Atlantic and Southern Ocean

NASA Astrophysics Data System (ADS)

Knudson, K. P.; Goldstein, S. L.; Pena, L.; Seguí, M. J.; Kim, J.; Yehudai, M.; Fahey, T.

2017-12-01

Understanding the relationship between meridional overturning circulation and climate is key to understanding the processes and feedbacks underlying future climate changes. North Atlantic Deep Water (NADW) represents a major water mass that participates in global oceanic circulation and undergoes substantial reorganization with climate changes on millennial and orbital timescales. Nd isotopes are semi-quantitative water mass tracers that reflect the mixing of end-member water masses, and their values in the Southern Ocean offer the ability to characterize NADW variability over time. Here, we present paleo-circulation records of Nd isotopes measured on fish debris and Fe-Mn encrusted foraminifera from ODP Sites 1090 (42° 54.82'S, 3702 m), and 1094 (53° 10.81'S, 2807 m). Site 1090 is located in the Cape Basin, SE Atlantic, near the lower boundary between NADW and Circumpolar Deep Water (CDW), while 1094 is in the Circumpolar Current. They are ideal locations to monitor changes in the export of NADW to the Southern Ocean. These new results build on previous work (Pena and Goldstein, 2014) to document meridional overturning changes in the Southern Ocean.

Characterization of excess pore pressures at the toe of the Nankai accretionary complex, Ocean Drilling Program sites 1173, 1174, and 808: Results of one-dimensional modeling

NASA Astrophysics Data System (ADS)

Gamage, K.; Screaton, E.

2006-04-01

Elevated fluid pore pressures play a critical role in the development of accretionary complexes, including the development of the décollement zone. In this study, we used measured permeabilities of core samples from Ocean Drilling Program (ODP) Leg 190 to develop a permeability-porosity relationship for hemipelagic sediments at the toe of the Nankai accretionary complex. This permeability-porosity relationship was used in a one-dimensional loading and fluid flow model to simulate excess pore pressures and porosities. Simulated excess pore pressure ratios (as a fraction of lithostatic pressure-hydrostatic pressure) using the best fit permeability-porosity relationship were lower than predicted from previous studies. We then tested sensitivity of excess pore pressure ratios in the underthrust sediments to bulk permeability, lateral stress in the prism, and a hypothetical low-permeability barrier at the décollement. Our results demonstrated significant increase in pore pressures below the décollement with lower bulk permeability, such as obtained by using the lower boundary of permeability-porosity data, or when a low-permeability barrier is added at the décollement. In contrast, pore pressures in the underthrust sediments demonstrated less sensitivity to added lateral stresses in the prism, although the profile of the excess pore pressure ratio is affected. Both simulations with lateral stress and a low-permeability barrier at the décollement resulted in sharp increases in porosity at the décollement, similar to that observed in measured porosities. Furthermore, in both scenarios, maximum excess pore pressure ratios were found at the décollement, suggesting that either of these factors would contribute to stable sliding along the décollement.

Tropical Atlantic climate and ecosystem regime shifts during the Paleocene-Eocene Thermal Maximum

NASA Astrophysics Data System (ADS)

Frieling, Joost; Reichart, Gert-Jan; Middelburg, Jack J.; Röhl, Ursula; Westerhold, Thomas; Bohaty, Steven M.; Sluijs, Appy

2018-01-01

The Paleocene-Eocene Thermal Maximum (PETM, 56 Ma) was a phase of rapid global warming associated with massive carbon input into the ocean-atmosphere system from a 13C-depleted reservoir. Many midlatitude and high-latitude sections have been studied and document changes in salinity, hydrology and sedimentation, deoxygenation, biotic overturning, and migrations, but detailed records from tropical regions are lacking. Here, we study the PETM at Ocean Drilling Program (ODP) Site 959 in the equatorial Atlantic using a range of organic and inorganic proxies and couple these with dinoflagellate cyst (dinocyst) assemblage analysis. The PETM at Site 959 was previously found to be marked by a ˜ 3.8 ‰ negative carbon isotope excursion (CIE) and a ˜ 4 °C surface ocean warming from the uppermost Paleocene to peak PETM, of which ˜ 1 °C occurs before the onset of the CIE. We record upper Paleocene dinocyst assemblages that are similar to PETM assemblages as found in extratropical regions, confirming poleward migrations of ecosystems during the PETM. The early stages of the PETM are marked by a typical acme of the tropical genus Apectodinium, which reaches abundances of up to 95 %. Subsequently, dinocyst abundances diminish greatly, as do carbonate and pyritized silicate microfossils. The combined paleoenvironmental information from Site 959 and a close-by shelf site in Nigeria implies the general absence of eukaryotic surface-dwelling microplankton during peak PETM warmth in the eastern equatorial Atlantic, most likely caused by heat stress. We hypothesize, based on a literature survey, that heat stress might have reduced calcification in more tropical regions, potentially contributing to reduced deep sea carbonate accumulation rates, and, by buffering acidification, also to biological carbonate compensation of the injected carbon during the PETM. Crucially, abundant organic benthic foraminiferal linings imply sustained export production, likely driven by prokaryotes. In sharp contrast, the recovery of the CIE yields rapid (≪ 10 kyr) fluctuations in the abundance of several dinocyst groups, suggesting extreme ecosystem and environmental variability.

Progress in Late Cretaceous planktonic foraminiferal stable isotope paleoecology and implications for paleoceanographic reconstructions

NASA Astrophysics Data System (ADS)

Petrizzo, Maria Rose; Falzoni, Francesca; Huber, Brian T.; MacLeod, Kenneth G.

2015-04-01

Paleoecological preferences proposed for Cretaceous planktonic foraminiferal taxa have traditionally been based on morphological analogies with depth-stratified modern species, on biofacies comparison in continental margin and deepwater settings, and limited oxygen and carbon stable isotope data. These studies concluded that large-sized, keeled and heavily calcified planktonic foraminifera generally lived at deeper levels in the surface waters than small-sized, thinner-walled non-keeled species. Stable isotope data have been used to infer information on paleotemperature, paleoceanography and paleoproductivity of ancient oceans and constrain biological paleo-activities (i.e. photosymbiosis and respiration) of fossil species. These studies have suggested that the depth-distribution model based on analogy with modern taxa might not be fully applicable for Cretaceous species, and found particularly 13C-enriched values in some Maastrichtian multiserial taxa that have been related to the activity of photosymbionts. We have collected about 1500 δ18O and δ13C species-specific analyses on glassy preserved planktonic foraminifera from Tanzania (Tanzania Drilling Project TDP sites 23, 28 and 32) and well-preserved planktonic foraminifera from other mid-low latitude localities (Shatsky Rise, northwestern Pacific Ocean, ODP Leg 198 Hole 1210B; Exmouth Plateau, eastern Indian Ocean, ODP Leg 122, Hole 762C; Eratosthenes Seamount, eastern Mediterranean, ODP Leg 160, Hole 967E; Blake Nose, central Atlantic Ocean, ODP Leg 171B, holes 1050C and 1052E) to investigate Late Cretaceous species paleoecological preferences, life strategies and depth distribution in the surface water column. Our results indicates that several large-sized (> 500 μm) double-keeled species belonging to the genera Dicarinella, Marginotruncana and Contusotruncana, generally interpreted as deep to thermocline dwellers, instead occupied shallow/warm layers of the water column, whilst not all biserial species were adapted to shallow layers and eutrophic environments (Falzoni et al., 2013; Falzoni et al., in prep.). Interestingly, globigeriniform planktonic foraminifera with meridional ornamentation (Paracostellagerina and Rugoglobigerina), a morphological feature generally considered to be genetically controlled and thus taxonomically significant, typically yield higher δ13C values than co-occurring finely ornamented morphotypes (Petrizzo et al., 2008). A possible explanation to these results invokes the presence of facultative photosymbionts enhancing test calcification or alternatively, the occurrence of ecophenotypes adapted to a different sea-surface 13C/12C ratio within the same fossil species (Falzoni et al., 2014). Finally, we discuss evidences against the traditional species depth-distribution model and highlight the restrictions in performing Late Cretaceous paleoenvironmental and paleoceanographic reconstructions based on shell morphology and/or inferred life strategies of planktonic foraminifera. References Falzoni, F., Petrizzo, M.R., MacLeod, K.G., Huber, B.T. (2013). Santonian-Campanian planktonic foraminifera from Tanzania, Shatsky Rise and Exmouth Plateau: species depth ecology and paleoceanographic inferences. Marine Micropaleontology 103, 15-29. Falzoni, F., Petrizzo, M.R., Huber, B.T., MacLeod, K.G. (2014). Insights into the meridional ornamentation of the planktonic foraminiferal genus Rugoglobigerina (Late Cretaceous) and implications for taxonomy. Cretaceous Research 47, 87-104. Petrizzo, M.R., Huber, B.T., Wilson, P.A., MacLeod, K.G. (2008). Late Albian paleoceanography of the western subtropical North Atlantic. Paleoceanography 23. http://dx.doi.org/10.1029/2007PA001517 (PA1213).

The Search for Organics (δ 13C and δ 15N) Throughout a Sub Basement Fossil Soil (Ocean Drilling Program, Leg 197): Implications for Earth/Mars deep subsurface

NASA Astrophysics Data System (ADS)

Bonaccorsi, R.

2003-12-01

Detecting organics buried deep beneath the surface of a planet is a fundamental step to constrain the presence and evolution of life on a planet. This is especially true for Mars with barren-life surface owing to extreme settings (UV flux, P atm and T). However, organics and/or viable microbes could still preserved at some deeper locations on Mars [e.g.,1]. This work presents the first nitrogen isotope (δ 15N) data for deeply buried Early Tertiary fossil soil Unit (Core 197-1206A-40R; 307.5-309.9 mbsf). They were RCB-cored from the volcanic basement at Site 1206 (Koko Seamount, ~34° 56' N; ~172° 9' E) during the ODP Leg 197 (Emperor Seamounts, north Pacific). These Fe-rich, palagonite-bearing soils were formed on the top of subsiding atolls and subsequently buried by lava flows in a near shore environment {[2]}. Burial rates higher than average subsidence rates ensured the isolation of these fossil soils in a present-day sub-basement setting and their decoupling from the ocean and the atmosphere for likely >54 Ma. Leg 197 soils contain very low, but reliable amounts of total organic carbon (TOC=0.01-0.12 %wt, +/- 0.02%, N=36; {[2-3]}). The single fossil soil unit has stable isotope values more negative (i.e., δ 13C-org. = -25.3 ‰ to -26.2‰ ;{[4]}) and δ 15N-tot = -9.5‰ to +2.5‰ than those of exposed Hawaiian counterparts (i.e., δ 15N-tot = >=0‰ to +8.5‰ ). This isotopically lighter Ntot could be interpreted as bacterial fractionation throughout the N-cycle either occurred in the past (Early Eocene/Late Paleocene) and changing organic source (C-3, C-4-plants, bacterial) and N-cycle associated processes. However the existing data-set {[2-4]} need to be compared with microbiological data to establish the potential for these soils to serve as a suitable analog for a possible Mars near-surface/deep biosphere. {[1]}Mancinelli, R.L, 2000. Planet. Space Sci., 48:1035-1043; {[2]} Shipboard Scientific Party, 2002, Proc. ODP, Init. Repts. 197: College Station, TX; {[3]} Bonaccorsi, R., 2002. EOS Trans AGU, 83(47), Fall Meet. Suppl. Abstract;{[4]}Meyers, P.A., 1997. Org. Geochem., 27, 5/6:213-259.

New High-Resolution Marine Single-Channel Seismic Data From the Emperor Seamounts: Initial Observations From ODP Leg 197

NASA Astrophysics Data System (ADS)

Kerr, B. C.; Scholl, D. W.

2001-12-01

In July-August of 2001, ODP Leg 197 drilled Detroit, Nintoku, and Koko Seamounts of the Emperor seamount chain to obtain cores of basaltic lava flows. These basalt cores will provide radiometric age and paleomagnetic data to accurately and precisely constrain the paleolatitude of the Hawaiian hotspot. In addition, recovered cores will determine temporal changes in the geochemistry of Hawaiian hotspot volcanic products. Prior to drilling, the JOIDES Resolution, performed high-resolution single-channel seismic surveys in the vicinity of preliminary site locations to help confirm suitability for drilling, and to collect digital seismic data. Generally, at least two seismic lines (about 10 km in length) cross directly over each drill site. The acoustic source consisted of a single SSI 80 cubic-inch water gun with a peak output frequency of approximately 50 Hz. Compared to most SCS data, low ship speeds (4.5-7 knots) and higher than typical firing rates (4 or 6 seconds) helped maximize horizontal resolution, resulting in shot-point spacings between 9 and 21.5 m. A 60-phone, 100-m-long Teledyne oil-filled streamer recorded the water gun shots at near-zero offset. At the end of the leg, a calibrated hydrophone, suspended about 30 m below the water gun, recorded the gun's source signature for 11-30 consecutive shots at each of 6, 5, 4, 3, and 2 m below the sea surface. Near-ideal weather conditions during each site survey produced data with high signal-to-noise ratios. The presence of volcaniclastic and/or soil interbeds, as well as highly vesicular lava flow units, significantly affected the seismic reflection character of the volcanic basement. Strong, laterally-coherent internal reflections in the volcanic basement indicate the presence of these layers, which exhibit low velocities and low bulk densities. Generally, laterally-coherent reflections cease where the number and thickness of the low-velocity interbeds diminish. Where the seamount sediment cap is underlain by dominantly massive basalt lava flows, a strong, non-reverberatory and low-frequency reflection marks the sediment-basement contact. Truncation of dipping lava flow reflections by other basement reflections suggests distinct lava flow sequences that can be mapped with further analysis. The two site surveys conducted over Detroit Seamount produced detailed seismic sections of the Meiji sediment drift body. Observations include a shallow angular unconformity indicative of a pattern of erosion and deposition produced by a strong bottom current such as that involved in forming the Meiji sediment drift. Sigmoidal clinoforms occur deeper in the Detroit sediment cap. Preliminary observations also suggest current-controlled drift deposits are present on top of Koko Seamount.

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.

Paleogene Seawater Osmium Isotope Records

NASA Astrophysics Data System (ADS)

Rolewicz, Z.; Thomas, D. J.; Marcantonio, F.

2012-12-01

Paleoceanographic reconstructions of the Late Cretaceous and early Cenozoic require enhanced geographic coverage, particularly in the Pacific, in order to better constrain meridional variations in environmental conditions. The challenge with the existing inventory of Pacific deep-sea cores is that they consist almost exclusively of pelagic clay with little existing age control. Pelagic clay sequences are useful for reconstructions of dust accumulation and water mass composition, but accurate correlation of these records to other sites requires improved age control. Recent work indicates that seawater Os isotope analyses provide useful age control for red clay sequences. The residence time of Os in seawater is relatively long compared to oceanic mixing, therefore the global seawater 187Os/188Os composition is practically homogeneous. A growing body of Late Cretaceous and Cenozoic data has constrained the evolution of the seawater Os isotopic composition and this curve is now a viable stratigraphic tool, employed in dating layers of Fe-Mn crusts (e.g., Klemm et al., 2005). Ravizza (2007) also demonstrated that the seawater Os isotopic composition can be extracted reliably from pelagic red clay sediments by analyzing the leached oxide minerals. The drawback to using seawater Os isotope stratigraphy to date Paleogene age sediments is that the compilation of existing data has some significant temporal gaps, notably between ~38 and 55 Ma. To improve the temporal resolution of the seawater Os isotope curve, we present new data from Ocean Drilling Program (ODP) Site 865 in the equatorial Pacific. Site 865 has excellent biostratigraphic age control over the interval ~38-55Ma. Preliminary data indicate an increase in the seawater composition from 0.427 at 53.4 Ma to 0.499 by 43 Ma, consistent with the apparent trend in the few existing data points. We also analyzed the Os isotopic composition recorded by oxide minerals at Integrated Ocean Drilling Program (IODP) Site U1370 to construct an age model for this predominantly pelagic clay section. The 187Os/188Os values generally increase from 0.312 at 64.46 mbsf to 0.531 at 28.26 mbsf. The low value recorded at 64.46 likely reflects the Os isotope minimum recorded across the K/Pg boundary, while the uppermost value likely correlates to the E/O interval. Comparison of the Os-derived ages with a crude linearly interpolated sedimentation rate age model reveals variations in sediment accumulation rate between 0.86 and 1.5 m/Myr.

Rare earth elements in Japan Sea sediments and diagenetic behavior of Ce/Ce∗: results from ODP Leg 127

USGS Publications Warehouse

Murray, R.; Buchholtz ten Brink, Marilyn R.; Brumsack, Hans-Juergen; Gerlach, David C.; Russ III, G. Price

1991-01-01

Ce/Ce* profiles at all three sites increase monotonically with depth, and record progressive diagenetic LREE fractionation. The observed Ce/Ce* record does not respond to changes in oxygenation state of the overlying water, and Ce/Ce* correlated slightly better with depth than with age. The downhole increase in Ce/Ce* at Site 794 and Site 797 is a passive response to diagenetic transfer of LREE (except Ce) from sediment to interstitial water. At Site 795, the overall lack of correlation between Ce/Ce* and L(ln/Ybnsuggests that other processes are occurring which mask the diagenetic behavior of all LREEs. First-order calculations of the Ce budget in Japan Sea waters and sediment indicate that ~20% of the excess Ce adsorbed by settling particles is recycled within the water column, and that an additional ~38% is recycled at or near the seafloor (data from Masuzawa and Koyama, 1989). Thus, because the remaining excess Ce is only ~10% of the total Ce, there is not a large source of Ce to the deeply buried sediment, further suggesting that the downhole increase in Ce/Ce* is a passive response to diagenetic behavior of the other LREEs. The REE chemistry of Japan Sea sediment therefore predicts successive downhole addition of LREEs to deeply-buried interstitial waters.

40 CFR Appendix B to Subpart G of... - Substitutes Subject to Use Restrictions and Unacceptable Substitutes

Code of Federal Regulations, 2010 CFR

2010-07-01

... Use Conditions Substitutes Application Substitute Decision Conditions Comments Electronics Cleaning w.... Electronics cleaning w/CFC-113 Dibromomethane Unacceptable High ODP; other alternatives exist. Electronics...

Optic disc pit with sectorial retinitis pigmentosa.

PubMed

Balikoglu-Yilmaz, Melike; Taskapili, Muhittin; Yilmaz, Tolga; Teke, Mehmet Yasin

2013-01-01

Sectorial retinitis pigmentosa (RP) and optic disc pit (ODP) are rare clinical conditions. We present a 40-year-old woman with a history of mild night blindness and decreased vision in the right eye for about 5 years. Fundus examination revealed retinal pigmentary changes in the superior and inferotemporal sectors covering the macula and reduced arterial calibre and ODP at the temporal edge of the optic disc. In addition, fundus autofluorescence, spectral-domain optical coherence tomography, fluorescein angiography, and multifocal electroretinogram scans confirmed these clinical findings. Visual acuity was decreased due to an atrophic-appearing foveal lesion. No intervention was suggested because of the poor visual potential. To the best of our knowledge, the present study is the first to describe coexistent optic disc pit and sectorial RP in the superior and inferotemporal sectors covering the macula in the same eye with figures.

Modelling the bathymetry of the Antarctic continental shelf

USGS Publications Warehouse

ten Brink, Uri S.; Rogers, William P.; Kirkham, R.M.

1992-01-01

Continental shelves are typically covered by relatively shallow waters (<200 m) which deepen gradually from the coast to the shelf edge. The continental shelf around Antarctica is deeper than normal (400-700m) and is characterized in many areas by a nearshore trough (up to 1 km deep) that gradually shallows toward the shelf edge. We examine the cause for the unusual shelf bathymetry of Antarctica by 2-D numerical models that simulate the bathymetry along seismic line ODP-119 in Prydz Bay. Line ODP-119 was chosen because it is tied to to 5 ODP boreholes, and because the margin underwent little recent tectonic activity or changes in the glacial drainage pattern. The numerical models incorporate several factors that are likely to influence the bathymetry, such as the load of the ice cap, the isostatic response of the lithosphere, thermal and tectnoic subsidence of the margin, sea level changes, and the patterns of erosion and sedimentation across the margin. The models show that the observed bathymetry can be produced almost entirely by the sum of the outer-shelf sediment loading and inner-shelf unloading and by the load of the slope sediments. A simple statistical mdoel demonstrates that this distribution pattern of erosion and deposition can be generated by multiple cycles of ice sheet advances across the shelf, whereby in each cycle a thin (a few tens of meters) uniform layer of sediments is eroded from under the ice sheet and is redeposited seaward of the grounding line.

Early Alcohol Exposure Disrupts Visual Cortex Plasticity in Mice

PubMed Central

Lantz, Crystal L.; Wang, Weili; Medina, Alexandre E.

2012-01-01

There is growing evidence that deficits in neuronal plasticity underlie the cognitive problems seen in fetal alcohol spectrum disorders (FASD). However, the mechanisms behind these deficits are not clear. Here we test the effects of early alcohol exposure on ocular dominance plasticity (ODP) in mice and the reversibility of these effects by phosphodiesterase (PDE) inhibitors. Mouse pups were exposed to 5 g/kg of 25% ethanol i.p. on postnatal days (P) 5, 7 and 9. This type of alcohol exposure mimics binge drinking during the third trimester equivalent of human gestation. To assess ocular dominance plasticity animals were monocularly deprived at P21 for 10 days, and tested using optical imaging of intrinsic signals. During the period of monocular deprivation animals were treated with vinpocetine (20mg/kg; PDE1 inhibitor), rolipram (1.25 mg/Kg; PDE4 inhibitor), vardenafil (3 mg/Kg; PDE5 inhibitor) or vehicle solution. Monocular deprivation resulted in the expected shift in ocular dominance of the binocular zone in saline controls but not in the ethanol group. While vinpocetine successfully restored ODP in the ethanol group, rolipram and vardenafil did not. However, when rolipram and vardenafil were given simultaneously ODP was restored. PDE4 and PDE5 are specific to cAMP and cGMP respectively, while PDE1 acts on both of these nucleotides. Our findings suggest that the combined activation of the cAMP and cGMP cascades may be a good approach to improve neuronal plasticity in FASD models. PMID:22617459

Identification of the mutation causing progressive retinal atrophy in Old Danish Pointing Dog.

PubMed

Karlskov-Mortensen, P; Proschowsky, H F; Gao, F; Fredholm, M

2018-06-01

Progressive retinal atrophy (PRA) is a common cause of blindness in many dog breeds. It is most often inherited as a simple Mendelian trait, but great genetic heterogeneity has been demonstrated both within and between breeds. In many breeds the genetic cause of the disease is not known, and until now, the Old Danish Pointing Dog (ODP) has been one of those breeds. ODP is one of the oldest dog breeds in Europe. Seventy years ago the breed almost vanished, but today a population still exists, primarily in Denmark but with some dogs in Germany and Sweden. PRA has been diagnosed in ODP since the late 1990s. It resembles late onset PRA in other dog breeds, and it is inherited as an autosomal recessive trait. In the present study, we performed whole-genome sequencing and identified a single base insertion (c.3149_3150insC) in exon 1 of C17H2orf71. This is the same mutation previously found to cause PRA in Gordon Setters and Irish Setters, and it was later found in Tibetan Terrier, Standard Poodle and the Polski Owczarek Nizinny. The presence of the mutation in such a diverse range of breeds indicates an origin preceding creation of modern dog breeds. Hence, we screened 262 dogs from 44 different breeds plus four crossbred dogs, and can subsequently add Miniature Poodle and another polish sheepdog, the Polski Owczarek Podhalanski, to the list of affected breeds. © 2018 Stichting International Foundation for Animal Genetics.

Calcium isotope evidence for suppression of carbonate dissolution in carbonate-bearing organic-rich sediments

NASA Astrophysics Data System (ADS)

Turchyn, Alexandra V.; DePaolo, Donald J.

2011-11-01

Pore fluid calcium isotope, calcium concentration and strontium concentration data are used to measure the rates of diagenetic dissolution and precipitation of calcite in deep-sea sediments containing abundant clay and organic material. This type of study of deep-sea sediment diagenesis provides unique information about the ultra-slow chemical reactions that occur in natural marine sediments that affect global geochemical cycles and the preservation of paleo-environmental information in carbonate fossils. For this study, calcium isotope ratios (δ 44/40Ca) of pore fluid calcium from Ocean Drilling Program (ODP) Sites 984 (North Atlantic) and 1082 (off the coast of West Africa) were measured to augment available pore fluid measurements of calcium and strontium concentration. Both study sites have high sedimentation rates and support quantitative sulfate reduction, methanogenesis and anaerobic methane oxidation. The pattern of change of δ 44/40Ca of pore fluid calcium versus depth at Sites 984 and 1082 differs markedly from that of previously studied deep-sea Sites like 590B and 807, which are composed of nearly pure carbonate sediment. In the 984 and 1082 pore fluids, δ 44/40Ca remains elevated near seawater values deep in the sediments, rather than shifting rapidly toward the δ 44/40Ca of carbonate solids. This observation indicates that the rate of calcite dissolution is far lower than at previously studied carbonate-rich sites. The data are fit using a numerical model, as well as more approximate analytical models, to estimate the rates of carbonate dissolution and precipitation and the relationship of these rates to the abundance of clay and organic material. Our models give mutually consistent results and indicate that calcite dissolution rates at Sites 984 and 1082 are roughly two orders of magnitude lower than at previously studied carbonate-rich sites, and the rate correlates with the abundance of clay. Our calculated rates are conservative for these sites (the actual rates could be significantly slower) because other processes that impact the calcium isotope composition of sedimentary pore fluid have not been included. The results provide direct geochemical evidence for the anecdotal observation that the best-preserved carbonate fossils are often found in clay or organic-rich sedimentary horizons. The results also suggest that the presence of clay minerals has a strong passivating effect on the surfaces of biogenic carbonate minerals, slowing dissolution dramatically even in relation to the already-slow rates typical of carbonate-rich sediments.

Relationship between compressional-wave velocity and porosity of sediments along subduction plate interface

NASA Astrophysics Data System (ADS)

Yamaguchi, M.; Hashimoto, Y.

2012-12-01

Evolution of physical properties of sediments along subduction interface has effects on wedge strength, wedge geometry, dewatering and dehydration processes, and seismic behavior. Sediments have initially more than 70% of porosity prior to subduction. Through underthrusting and accretion, porosity of sediments decreases by compaction and cementation to be lithified sediments. The purpose of this study is to understand evolution of physical properties from a state before subduction to a state within a wedge using a relationship between compressional-wave velocity and porosity. In this study, we obtained new data for sediments from a reference site in IODP NanTroSEIZE, Expedition 333. In addition to that, we have complied velocity-porosity relationships for the samples and also for previous studies from NanTroSEIZE (off Kumano) (Hashimoto et al., 2010, 2011), ODP Leg 190 (off Shikoku) (Hoffman and Tobin, 2004) and ODP Leg 170 (off Costa Rica) (Gettemy and Tobin, 2003). Velocity measurement procedure in this study to obtain new data is as following: Two pumps were used to control pore fluid pressure and confining pressure. The pore pressure of 1000kPa was kept under drained conditions. Confining (effective) pressure was increased stepwise in the measurements. Velocity measurements were conducted under isotropic pressure conditions. Confining pressure was pressurized in tens seconds and kept for more than 8 hours for next step to obtain equilibrium conditions between effective pressure and sediments strain. Lead zirconate titanate (PZT) shear wave transducers (500kHz) were used in a source-receiver pair to measure wave speed. Porosity and P-wave velocity ranges about 27 - 75% and 1.4 - 2.2 km/s in this study, respectively. In the comparison in Vp-porosity relationships between sedimetns from reference sites and others, sediments were classified into two, simply compacted sediments (reference site and slope sediments) and wedge sediments. Different trends in Vp-porosity relationships were observed for the classified sediments. For compacted sediments, Vp-porosity relationships are along the global empirical relationships (Erickson and Jarrard 1988) and almost within the area between normal and highly compaction curves. On the other hand, some of Vp-porosity relationships for wedge sediments represent trends with higher velocity at a porosity. Such trend was observed for wedge sediments from Site C0001 and C0004. Those higher Vp trend in Vp-porosity relationship for wedge sediments can be explained by shear strain of sediments and/or cementation. Even though the velocity measurements was conducted under hydrostatic condition, we examined the void ratio-porosity curve as a kind of compaction curve. On the basis of the curves, break points were observed at the pressure which corresponds to the effective pressure assuming the hydrostatic pore fluid pressure. The result suggests that the sediments were under condition of normal compaction. Some of void ratio-porosity curve represent a evidence of weak cement which can correspond with anomaly in porosity-depth curve in the shallow portion of the reference sites.

An Early Pleistocene high-resolution paleoclimate reconstruction from the West Turkana (Kenya) HSPDP drill site

NASA Astrophysics Data System (ADS)

Stockhecke, Mona; Beck, Catherine; Brown, Erik T.; Cohen, Andrew; Deocampo, Daniel M.; Feibel, Craig S.; Pelletier, Jon D.; Rabideaux, Nathane M.; Sier, Mark

2016-04-01

The Hominin Sites and Paleolakes Drilling Project (HSPDP), and the related Olorgesailie Drilling Project (ODP), recovered ~2 km of drill core since 2012. At the HSPDP West Turkana Kaitio (WTK) site a 216 m-long core that covers the Early Pleistocene time window (1.3 to 1.87 Ma) during which hominids first expanded out of Africa and marine records document reorganization of tropical climate and the development of the strong Walker circulation. WTK carries particular interest for paleoclimate and paleoenvironmental reconstructions as it is located only 2.5 km from the location of one of the most complete hominin skeletons ever recovered (Nariokotome Boy). XRF core scanning data provide a means of evaluating records of past environmental conditions continuously and at high resolution. However, the record contains complex lithologies reflecting repeated episodes of inundation and desiccation along a dynamic lake margin. Here we present a methodological approach to address the highly variable lithostratigraphy of the East African records to establish comprehensive paleoclimate timeseries. The power spectrum of the presented hydroclimate record peaks at Milankovitch cycles, qualifying HSPDP drill cores from the Turkana Basin to be used as high-resolution Early Pleistocene paleoclimate archive. Comparing these data with marine climate reconstructions sheds light into athmospheric processes and continental climate dynamics.

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.

Proceedings of the ocean drilling program: New Jersey continental slope and rise

USGS Publications Warehouse

Mountain, Gregory S.; Miller, Kenneth G.; Blum, Peter; Alm, Per-Gunnar; Aubry, Marie-Pierre; Burckle, Lloyd H.; Christensen, Beth A.; Compton, J.; Damuth, John E.; Deconinck, Jean-François; De Verteuil, L.; Fulthorpe, Craig S.; Gartner, Stefan; Guerin, Gilles; Hesselbo, Stephen P.; Hoppie, Bryce; Katz, Miriam E.; Kotake, Nobuhiro; Lorenzo, Juan Manuel; McCracken, Stuart; McHugh, Cecilia; Quayle, Wendy C.; Saito, Yoshiki; Snyder, Scott W.; ten Kate, Warner G.; Urbat, M.; Van Fossen, Mickey C.; Vecsei, Adam

1996-01-01

The Scientific Results volumes of the Proceedings of the Ocean Drilling Program contain specialty papers presenting the results of extensive research in various aspects of scientific ocean drilling. The authors of the papers published in this volume have enabled future investigators to gain ready access to the results of their research, and I acknowledge their contributions with thanks. Each paper submitted to a Scientific Results volume undergoes rigorous peer review by at least two specialists in the author's research field. A paper typically goes through at least one revision cycle before being accepted for publication. We seek to maintain a peer-review system comparable to those of the most highly regarded journals in the geological sciences. Each Scientific Results volume has an Editorial Review Board that is responsible for obtaining peer reviews of papers submitted to the volume. This board usually is made up of the two co-chief scientists for the cruise, the ODP staff scientist for the cruise, and one external specialist who is familiar with the geology of the area investigated. In addition, the volume has an ODP staff editor who assists with manuscripts that require English-language attention and who coordinates volume assembly. Scientific Results volumes may also contain short reports of useful data that are not ready for final interpretation. Papers of this type, which may be found together in a section in the back of the volume, are called Data Reports and include no interpretation of results. Data Report papers are read carefully by at least one specialist to make sure they are well organized, comprehensive, and discuss the techniques or procedures thoroughly. To acknowledge the contributions made by this volume's Editorial Review Board, the Board members are designated Editors of the volume and are so listed on the title page. Reviewers of manuscripts for this volume, whose efforts are so essential to the success of the publication, are listed in the front of the book, without attribution to a particular manuscript. On behalf of the Ocean Drilling Program, I extend sincere appreciation to members of the Editorial Review Boards and to the reviewers for giving their generous contribution of time and effort, which ensures that only papers of high scientific quality are published in the Proceedings.

Endmember analysis of isothermal and high-temperature magnetization data from ODP 910C, Yermak Plateau, NW Svalbard

NASA Astrophysics Data System (ADS)

Fabian, Karl; Knies, Jochen; Kosareva, Lina; Nurgaliev, Danis

2017-04-01

Room temperature magnetic initial curves, upper hysteresis curves, acquisition curves of induced remanent magnetization (IRM), and backfield (BF) curves have been measured between -1.5 T and 1.5 T for more than 430 samples from Ocean Drilling Program (ODP) Hole 910C. The core was drilled in 556.4 m water depth on the southern Yermak Plateau (80°15.896'N, 6°35.430'E), NW Svalbard. In total, 507.4 m of sediments were cored, and average recovery was 57%, with 80% between 170 and 504.7 meter below seafloor (mbsf). For this study, the borehole was re-sampled between 150 mbsf and 504.7 mbsf for environmental magnetic, inorganic geochemical, and sedimentological analyses (443 samples). The lithology is mainly silty-clay with some enrichments of fine sands in the lower section (below 400 mbsf). For all samples, a Curie express balance was used to obtain the temperature dependence of induced magnetization in air at a heating rate of 100 °C/min up to a maximum temperature of 800 °C. The hysteresis curves were used to infer classical hysteresis parameters like saturation remanence (Mrs), saturation magnetization (Ms), remanence coercivity (Hcr) or coercivity (Hc). In addition several other parameters, like hysteresis energy, high-field slope or saturation field have been determined and help to characterize the down-core variation of the magnetic fractions. Acquisition curves of isothermal remanent magnetization are decomposed into endmembers using non-negative matrix factorization. The obtained mixing coefficients decompose hysteresis loops, back-field, thermomagnetic curves, geochemistry, and sedimentological parameters into their related endmember components. Down-core variation of the endmembers enables reconstruction of sediment transport processes and in-situ formation of magnetic mineral phases.

Continental Supply and Climate Variations In Mediterranean Pliocene

NASA Astrophysics Data System (ADS)

Foucault, Alain; Melieres, Frederic; Combourieu-Nebaout, Nathalie

From the Pliocene period to present day, the Mediterranean marine sedimentation is characterised by cycles resulting from climate variations, which are controlled by Earth orbital parameters. Theses cycles are evidenced in the sediment content vari- ation, particularly through composition and proportions of the material supplied by continents. Concerning mineral supply we were able to show alternations of humid pe- riods, during which fluvial supply is dominant, and arid periods, during which eolian supply from the southern borderlands of the Mediterranean is significant. Concerning organic supply, palynological study confirms theses climatic controls, emphasising the importance of fresh water runoff during humid periods. This synthetic image re- sults from the study of several Pliocene Mediterranean stratigraphical series located in Sicily (Lido Rosselo, Punta di Maiata, Punta Piccola), Calabria (Monte Singa, Vrica) or cored during Leg 160 ODP (Hole 964). References: FOUCAULT A. et MELIERES F. (1995).- Nature et origine des cy- cles sédimentaires métriques du Pliocène de l'Ouest méditerranéen d'après l'étude du contenu terrigène de la Formation Narbone (Punta Piccola, Sicile, Italie). C. R Ac. Sci. Paris, t. 321, II a, p. 869-876. MELIERES F., FOUCAULT A. and BLANC-VALLERON, M.M. (1998). Mineralogical record of cyclic climate changes in Mediterranean Mid-Pliocene deposits from Hole 964A (Ionian Basin) and from Punta Piccola (Sicily). In Robertson, A.H.F., Emeis, K.-C., Richter, C., and Camer- lenghi, A. (Eds.), 1998. Proc. ODP., Sci. Results, 160; College Station, TX (Ocean Drilling Program), p. 219-226. FOUCAULT, A. and MELIERES, F. (2000). Palaeocli- mate cyclicity in central Mediterranean Pliocene sediments: the mineralogical signal. Palaeogeography, Palaeoclimatology, Palaeoecology, 148: 311-323.

Orbital, tectonic and oceanographic controls on Pliocene climate and atmospheric circulation in Arctic Norway

NASA Astrophysics Data System (ADS)

Panitz, Sina; Salzmann, Ulrich; Risebrobakken, Bjørg; De Schepper, Stijn; Pound, Matthew J.; Haywood, Alan M.; Dolan, Aisling M.; Lunt, Daniel J.

2018-02-01

During the Pliocene Epoch, a stronger-than-present overturning circulation has been invoked to explain the enhanced warming in the Nordic Seas region in comparison to low to mid-latitude regions. While marine records are indicative of changes in the northward heat transport via the North Atlantic Current (NAC) during the Pliocene, the long-term terrestrial climate evolution and its driving mechanisms are poorly understood. We present the first two-million-year-long Pliocene pollen record for the Nordic Seas region from Ocean Drilling Program (ODP) Hole 642B, reflecting vegetation and climate in Arctic Norway, to assess the influence of oceanographic and atmospheric controls on Pliocene climate evolution. The vegetation record reveals a long-term cooling trend in northern Norway, which might be linked to a general decline in atmospheric CO2 concentrations over the studied interval, and climate oscillations primarily controlled by precession (23 kyr), obliquity (54 kyr) and eccentricity (100 kyr) forcing. In addition, the record identifies four major shifts in Pliocene vegetation and climate mainly controlled by changes in northward heat transport via the NAC. Cool temperate (warmer than present) conditions prevailed between 5.03-4.30 Ma, 3.90-3.47 Ma and 3.29-3.16 Ma and boreal (similar to present) conditions predominated between 4.30-3.90 Ma, 3.47-3.29 and after 3.16 Ma. A distinct decline in sediment and pollen accumulation rates at c. 4.65 Ma is probably linked to changes in ocean currents, marine productivity and atmospheric circulation. Climate model simulations suggest that changes in the strength of the Atlantic Meridional Overturning Circulation during the Early Pliocene could have affected atmospheric circulation in the Nordic Seas region, which would have affected the direction of pollen transport from Scandinavia to ODP Hole 642B.

Three-dimensional distribution of gas hydrate beneath southern Hydrate Ridge: Constraints from ODP Leg 204

USGS Publications Warehouse

Trehu, A.M.; Long, P.E.; Torres, M.E.; Bohrmann, G.; Rack, F.R.; Collett, T.S.; Goldberg, D.S.; Milkov, A.V.; Riedel, M.; Schultheiss, P.; Bangs, N.L.; Barr, S.R.; Borowski, W.S.; Claypool, G.E.; Delwiche, M.E.; Dickens, G.R.; Gracia, E.; Guerin, G.; Holland, M.; Johnson, J.E.; Lee, Y.-J.; Liu, C.-S.; Su, X.; Teichert, B.; Tomaru, H.; Vanneste, M.; Watanabe, M. E.; Weinberger, J.L.

2004-01-01

Large uncertainties about the energy resource potential and role in global climate change of gas hydrates result from uncertainty about how much hydrate is contained in marine sediments. During Leg 204 of the Ocean Drilling Program (ODP) to the accretionary complex of the Cascadia subduction zone, we sampled the gas hydrate stability zone (GHSZ) from the seafloor to its base in contrasting geological settings defined by a 3D seismic survey. By integrating results from different methods, including several new techniques developed for Leg 204, we overcome the problem of spatial under-sampling inherent in robust methods traditionally used for estimating the hydrate content of cores and obtain a high-resolution, quantitative estimate of the total amount and spatial variability of gas hydrate in this structural system. We conclude that high gas hydrate content (30-40% of pore space or 20-26% of total volume) is restricted to the upper tens of meters below the seafloor near the summit of the structure, where vigorous fluid venting occurs. Elsewhere, the average gas hydrate content of the sediments in the gas hydrate stability zone is generally <2% of the pore space, although this estimate may increase by a factor of 2 when patchy zones of locally higher gas hydrate content are included in the calculation. These patchy zones are structurally and stratigraphically controlled, contain up to 20% hydrate in the pore space when averaged over zones ???10 m thick, and may occur in up to ???20% of the region imaged by 3D seismic data. This heterogeneous gas hydrate distribution is an important constraint on models of gas hydrate formation in marine sediments and the response of the sediments to tectonic and environmental change. ?? 2004 Published by Elsevier B.V.

General Approach for Rock Classification Based on Digital Image Analysis of Electrical Borehole Wall Images

NASA Astrophysics Data System (ADS)

Linek, M.; Jungmann, M.; Berlage, T.; Clauser, C.

2005-12-01

Within the Ocean Drilling Program (ODP), image logging tools have been routinely deployed such as the Formation MicroScanner (FMS) or the Resistivity-At-Bit (RAB) tools. Both logging methods are based on resistivity measurements at the borehole wall and therefore are sensitive to conductivity contrasts, which are mapped in color scale images. These images are commonly used to study the structure of the sedimentary rocks and the oceanic crust (petrologic fabric, fractures, veins, etc.). So far, mapping of lithology from electrical images is purely based on visual inspection and subjective interpretation. We apply digital image analysis on electrical borehole wall images in order to develop a method, which augments objective rock identification. We focus on supervised textural pattern recognition which studies the spatial gray level distribution with respect to certain rock types. FMS image intervals of rock classes known from core data are taken in order to train textural characteristics for each class. A so-called gray level co-occurrence matrix is computed by counting the occurrence of a pair of gray levels that are a certain distant apart. Once the matrix for an image interval is computed, we calculate the image contrast, homogeneity, energy, and entropy. We assign characteristic textural features to different rock types by reducing the image information into a small set of descriptive features. Once a discriminating set of texture features for each rock type is found, we are able to discriminate the entire FMS images regarding the trained rock type classification. A rock classification based on texture features enables quantitative lithology mapping and is characterized by a high repeatability, in contrast to a purely visual subjective image interpretation. We show examples for the rock classification between breccias, pillows, massive units, and horizontally bedded tuffs based on ODP image data.

IBA analysis of some precolumbian gilded-copper samples

NASA Astrophysics Data System (ADS)

Andrade, E.; Murillo, G.; Policroniades, R.; Acosta, L.; Zavala, E. P.; Rocha, M. F.; Centeno, S. A.

2005-10-01

The elemental composition and depth profiles obtained by IBA techniques on some gilded-copper fragments from the Moche site of Loma Negra, in the Piura Valley, on the Northern Coast of Perú are presented in this article. A previous radiocarbon dating of a wooden fragment indicated that Loma Negra was occupied around 295 AD. A PIXE analysis using a 2.6 MeV external proton beam, was used to obtain the concentration of trace elements in the samples. RBS analyses using 2.72 MeV 4He+ and 12.0 MeV 12C3+ were used to obtain the Au, Ag, Cu atomic profiles. NRA with a 1.02 MeV deuteron beam was used to measure the oxygen and carbon concentrations through the 16O(d,p) 17O, 16O(d,α) 14N and 12C(d,p0) 13C reactions.

PRISM3 DOT1 Atlantic Basin Reconstruction

USGS Publications Warehouse

Dowsett, Harry; Robinson, Marci; Dwyer, Gary S.; Chandler, Mark; Cronin, Thomas

2006-01-01

PRISM3 DOT1 (Pliocene Research, Interpretation and Synoptic Mapping 3, Deep Ocean Temperature 1) provides a three-dimensional temperature reconstruction for the mid-Pliocene Atlantic basin, the first of several regional data sets that will comprise a global mid-Pliocene reconstruction. DOT1 is an alteration of modern temperature values for the Atlantic Ocean in 4 degree x 5 degree cells in 13 depth layers for December 1 based on Mg/Ca-derived BWT estimates from seventeen DSDP and ODP Sites and SST estimates from the PRISM2 reconstruction (Dowsett et al., 1999). DOT1 reflects a vaguely modern circulation system, assuming similar processes of deep-water formation; however, North Atlantic Deep Water (NADW) production is increased, and Antarctic Bottom Water (AABW) production is decreased. Pliocene NADW was approximately 2 degreesC warmer than modern temperatures, and Pliocene AABW was approximately 0.3 degreesC warmer than modern temperatures.

Organic carbon isotopes through the mid-Miocene: lack of a global signal

NASA Astrophysics Data System (ADS)

Gröcke, D. R.; Diester-Haaß, L.; Billups, K.

2006-12-01

The mid-Miocene Monterey Event is characterized by a period of extreme warmth and heaviest benthic and planktic δ13C values of the Cenozoic, followed by rapid cooling and associated extension of Antarctic ice sheets and decreasing δ13C values since ca. 14 Ma. We present bulk organic-carbon results from three ODP sites located in the Atlantic Ocean (Sites 608, 925, and 1265). What is initially apparent in the δ13Corg records from these sites is the lack of a positive δ13C excursion that is recorded in foraminifera. In a concurrent study, benthic foraminiferal accumulation rate derived productivity increases at all three sites between 17.5 13.5 Ma, paralleling the general trend of increasing foraminiferal δ13C records. However, an inverse relationship between δ13Corg and foraminiferal- derived productivity rates suggest that productivity is driven by cyclic changes in upwelling of oxidized, nutrient-rich bottom waters. During this period also there is no change in delta-delta between carbonate and organic matter, which indicates that there were no changes in pCO2 during the mid-Miocene. Also, δ13Corg values are typical of C3 photosynthesis in Site 608 and 1265 however the equatorial site (925) shows considerable variation suggestive of the presence of C3 input back to at least 16 Ma. Further work on δ13Corg and productivity proxies through the Miocene is critical in order to understand the global carbon cycle in the oceanic and atmospheric realms.

Combined organic and inorganic geochemical reconstruction of paleodepositional conditions of a Pliocene sapropel from the eastern Mediterranean Sea

NASA Astrophysics Data System (ADS)

Rinna, J.; Warning, B.; Meyers, P. A.; Brumsack, H.-J.; Rullkötter, J.

2002-06-01

Layers of organic-carbon-rich sapropels in the sediment record of the Mediterranean Sea give evidence of repetitive changes in regional Plio-Pleistocene climate. Results from biomarker molecule and major and trace element analyses of closely spaced samples are used to reconstruct the conditions leading to deposition of a Pliocene sapropel at Ocean Drilling Program (ODP) Site 969 on the Mediterranean Ridge. Organic carbon concentrations increase from 0.2% outside the sapropel and peak to more than 30% within it. Major and trace elemental composition and biomarker-derived parameters indicate elevated productivity, depletion of water-column dissolved-oxygen content, and changes in sediment provenance in response to climatic changes. Budgets of rhenium, thallium, and other trace metals indicate that deep-water exchange between the Mediterranean subbasins and the Atlantic Ocean was not completely interrupted during sapropel formation. Enrichment factors of redox-sensitive and sulfide-forming trace metals as well as the presence of isorenieratene derivatives and high stanol/sterol ratios point to an extended zone of anoxic water masses. Depth profiles of biomarker compositions (sterols, long-chain alkenones, alkandiols and -ketols, fatty acids) indicate great floral diversity during deposition of a single sapropel and highlight the sensitive response of the marine community to variable environmental conditions. Changes in water mass circulation and eolian transport can be reconstructed by use of both lithogenic elements and average chain lengths of n-alkanes (ACL index).

Testing Urey's carbonate-silicate cycle using the calcium isotopic composition of sedimentary carbonates

NASA Astrophysics Data System (ADS)

Blättler, Clara L.; Higgins, John A.

2017-12-01

Carbonate minerals constitute a major component of the sedimentary geological record and an archive of a fraction of the carbon and calcium cycled through the Earth's surface reservoirs for over three billion years. For calcium, carbonate minerals constitute the ultimate sink for almost all calcium liberated during continental and submarine weathering of silicate minerals. This study presents >500 stable isotope ratios of calcium in Precambrian carbonate sediments, both limestones and dolomites, in an attempt to characterize the isotope mass balance of the sedimentary carbonate reservoir through time. The mean of the dataset is indistinguishable from estimates of the calcium isotope ratio of bulk silicate Earth, consistent with the Urey cycle being the dominant mechanism exchanging calcium among surface reservoirs. The variability in bulk sediment calcium isotope ratios within each geological unit does not reflect changes in the global calcium cycle, but rather highlights the importance of local mineralogical and/or diagenetic effects in the carbonate record. This dataset demonstrates the potential for calcium isotope ratios to help assess these local effects, such as the former presence of aragonite, even in rocks with a history of neomorphism and recrystallization. Additionally, 29 calcium isotope measurements are presented from ODP (Ocean Drilling Program) Site 801 that contribute to the characterization of altered oceanic crust as an additional sink for calcium, and whose distinct isotopic signature places a limit on the importance of this subduction flux over Earth history.

Elemental concentration variations in Plio-Pleistocene sediments from ODP Site 1143 (southern South China Sea) obtained by XRF analyses

NASA Astrophysics Data System (ADS)

Tian, J.; Xie, X.; Jin, H.; Wang, P.; Jian, Z.

2009-12-01

Energy dispersive X-ray fluorescence (XRF) scanning technology provides the most accurate and most economic analytical methods for the determination of major and minor elements of the deep-sea sediment ranging from sodium (11) to uranium (92). Scanning on the smooth core surface by XRF Core scanner is reliable and non-destructive to the sediment, requiring little or no time to prepare the core. This method overcomes the drawback of the traditional analytical method by ICP-AES or ICP-MS which requires long time for sample preparation. Thus, it makes it viable to reconstruct long and high-resolution elemental time series from sediment cores. We have performed relatively elemental concentration analyses on the deep sea sediment cores from ODP site 1143 (southern SCS) down to 190.77 mcd (meters composite depth) by XRF core scanner. The depth resolution of the scanning is 1 cm, equivalent to a time resolution of ~250 years. The age model is based on tuning the benthic foraminiferal d18O at Site 1143 to obliquity and precession (Tian et al., 2002) which indicates that the 190.77 meters long sediment spans the past 5 Myr. We compared the records between 99.5 and 136.46 mcd with the elemental records from the same site obtained by Philips PW 2400 X-ray spectrometer (Wehausen et al., online publication). Comparison reveals, regardless of the absolute changes of the elements, that the elemental records (Si, Ti, Al, Fe, Mn, Ca, K, P, Ba, Rb, Sr) obtained by two methods are nearly the same. Results show that the relative concentration variations of the productivity related elements such as Ba and Ca display distinctive glacial-interglacial cycles for the past 5 Myr. These productivity cycles recorded show one-on-one relationship with the glacial-interglacial cycles of the global ice volume change recorded in the benthic foraminiferal d18O. The glacial-interglacial cycles in productivity and global ice volume changes are consistent with each other not only in amplitude but also in secular variations. The benthic d18O implies the final formation of the northern hemisphere glaciation between ~2.5 Ma and ~3.3 Ma, as indicated by gradually increased values of d18O. During this period, both Ba and Ca show gradually increased values of relative concentration, indicating increased productivity which was probably caused by intensified East Asia summer monsoon. The close relationship of the productivity related elemental variations with benthic foraminiferal d18O reveals that the Plio-Pleistocene variations of the East Asian monsoon have been greatly dominated by global ice volume change. Although the elements related to terrigenous detrital matter composition of site 1143 such as Ti, Fe, As, Co and Ni display distinct glacial-interglacial cycles for the past 5 Myr, they display different patterns in secular variation with that of the benthic foraminiferal d18O. The mismatch indicates that besides northern hemisphere glaciation other multiple processes including changes in provenance and weathering intensity caused by monsoonal climate variability and sea level fluctuations could have affected the terrigenous detrital matter composition of site 1143.

Optic Disc Pit with Sectorial Retinitis Pigmentosa

PubMed Central

Taskapili, Muhittin; Yilmaz, Tolga; Teke, Mehmet Yasin

2013-01-01

Sectorial retinitis pigmentosa (RP) and optic disc pit (ODP) are rare clinical conditions. We present a 40-year-old woman with a history of mild night blindness and decreased vision in the right eye for about 5 years. Fundus examination revealed retinal pigmentary changes in the superior and inferotemporal sectors covering the macula and reduced arterial calibre and ODP at the temporal edge of the optic disc. In addition, fundus autofluorescence, spectral-domain optical coherence tomography, fluorescein angiography, and multifocal electroretinogram scans confirmed these clinical findings. Visual acuity was decreased due to an atrophic-appearing foveal lesion. No intervention was suggested because of the poor visual potential. To the best of our knowledge, the present study is the first to describe coexistent optic disc pit and sectorial RP in the superior and inferotemporal sectors covering the macula in the same eye with figures. PMID:23781365

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.

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.

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.

Abyssal and hydrated mantle wedge serpentinised peridotites: a comparison of the 15°20'N fracture zone and New Caledonia serpentinites

NASA Astrophysics Data System (ADS)

Mothersole, Fiona Elizabeth; Evans, Katy; Frost, B. Ronald

2017-08-01

Subduction of serpentinised mantle transfers oxidised and hydrated mantle lithosphere into the Earth, with consequences for the oxidation state of sub-arc mantle and the genesis of arc-related ore deposits. The role of subducted serpentinised mantle lithosphere in earth system processes is uncertain because subduction fluxes are poorly constrained. Most subducted serpentinised mantle is serpentinised on the ocean floor settings. Yet this material is poorly represented in the literature because it is difficult to access. Large volumes of accessible serpentinite are available in ophiolite complexes, and most interpretations of subduction fluxes associated with ultramafic rocks are based on ophiolite studies. Seafloor and ophiolite serpentinisation can occur under different conditions, so it is necessary to assess if ophiolite serpentinites are a good proxy for seafloor serpentinites. Serpentinites sampled during ODP cruise 209 were compared with serpentinites from New Caledonia. The ODP209 serpentinites were serpentinised by modified seawater in a shallow hydrothermal seafloor setting. The New Caledonia serpentinites were serpentinised in a mantle wedge setting by slab-derived fluids, with possible contributions from oceanic serpentinisation and post-obduction serpentinisation. Petrological, whole rock and mineralogical analyses were combined to compare the two sample sets. Petrologically, the evolution of serpentinisation was close to identical in the two environments. However, more oxidised iron, Cl, S and C is present in serpentine from the ODP209 serpentinites relative to the New Caledonia serpentinites. Given these observations, the use of serpentinites from different geodynamic settings as a proxy for abyssal serpentinites from spreading settings must be undertaken with caution.

Laparoscopic versus open distal pancreatectomy-a propensity score-matched analysis from the German StuDoQ|Pancreas registry.

PubMed

Wellner, Ulrich Friedrich; Lapshyn, Hryhoriy; Bartsch, Detlef K; Mintziras, Ioannis; Hopt, Ulrich Theodor; Wittel, Uwe; Krämling, Hans-Jörg; Preissinger-Heinzel, Hubert; Anthuber, Matthias; Geissler, Bernd; Köninger, Jörg; Feilhauer, Katharina; Hommann, Merten; Peter, Luisa; Nüssler, Natascha C; Klier, Thomas; Mansmann, Ulrich; Keck, Tobias

2017-02-01

The aim of this study was to assess intraoperative, postoperative, and oncologic outcome in patients undergoing laparoscopic distal pancreatectomy (LDP) versus open distal pancreatectomy (ODP) for benign and malignant lesions of the pancreas. Data from patients undergoing distal pancreatic resection were extracted from the StuDoQ|Pancreas registry of the German Society for General and Visceral Surgery. After propensity score case matching, groups of LDP and ODP were compared regarding demography, comorbidities, operative details, histopathology, and perioperative outcome. At the time of data extraction, the StuDoQ|Pancreas registry included over 3000 pancreatic resections from over 50 surgical departments in Germany. Data from 353 patients undergoing ODP (n = 254) or LDP (n = 99) from September 2013 to February 2016 at 29 institutions were included in the analysis. Baseline data showed a strong selection bias in LDP patients, which disappeared after 1:1 propensity score matching. A comparison of the matched groups disclosed a significantly longer operation time, higher rate of spleen preservation, more grade A pancreatic fistula, shorter hospital stay, and increased readmissions for LDP. In the small group of patients operated for pancreatic cancer, a lower lymph node yield with a lower lymph node ratio was apparent in LDP. LDP needed more time but potential advantages include increased spleen preservation and shorter hospital stay, as well as a trend for less transfusion, ventilation, and mortality. LDP for pancreatic cancer was performed rarely and will need critical evaluation in the future. Data from a prospective randomized registry trial is needed to confirm these results.

The Evolution of Northern Hemisphere Glaciation

NASA Astrophysics Data System (ADS)

Wright, J. D.

2001-05-01

For much of the last 50 million years, high-latitude regions remained too warm to allow snow to accumulate and form ice sheets. Shackleton et al. (1984) published a landmark paper correlating the first occurrence of ice-rafted detritus (IRD) observed at Rockall Plateau with a prominent increase in benthic foraminiferal d18O values during the late Pliocene. These late Pliocene to Pleistocene ice sheets were modulated on an orbital frequency and have characterized the global climate over the past 2.6 myr (Shackleton and Opdyke, 1973; Shackleton et al., 1984; Ruddiman, et al., 1986). During the early Pliocene, northern hemisphere glaciation (NHG) variations were less significant (Jansen et al., 1993). Our understanding of the Plio-Pleistocene ice sheet cycles can be viewed from two different perspectives. When viewed from the late Pleistocene, the fundamental question is what changed near the early/late Pliocene boundary to produce the large-scale, glacial-interglacial cycles of the past 2.6 Ma. In contrast, the view from the middle to late Miocene is quite different. Since the pioneering work of Shackleton et al. (1984), the record of NHG has been extended further back in time with drilling in the Norwegian Sea (ODP Leg 104). At Sites 642 and 644, IRD was found throughout the late Miocene and back to ~12 Ma. More recent drilling in the high northern latitudes occurred on ODP Leg 151. Site 909 recovered a middle Miocene section from the Fram Straits with rounded quartz grains that were interpreted as IRD (Wolf-Welling et al., 1996). Age estimates for those sediments place the first northern hemisphere ice sheets at least as old as 14 Ma. The occurrence of sand-sized particles (>1000 μm) and coal below this level indicates the possibility of glacial activity in the Northern Hemisphere as early as 16 Ma. Thus, the late Pliocene to Pleistocene cycles appear to be the resumption of the glacial-interglacial pattern that began during the Miocene. While the Miocene ice sheets were much smaller than their late Pliocene and Pleistocene counterparts, their presence casts the climate dynamics of the Neogene in a new light. Thus, understanding the middle to late Miocene climatic changes is key to understanding the Plio-Pleistocene climates.

Progress on the NEPTUNE Canada Seismograph Network

NASA Astrophysics Data System (ADS)

Rogers, G. C.; Meldrum, R. D.; Heesemann, M.; Mulder, T. L.; Brillon, C. D.; Cassidy, J. F.

2012-12-01

NEPTUNE Canada is the world's first deep-sea regional multi-disciplinary scientific cabled ocean observatory. In the fall of 2007 an 800 kilometer ring of powered fiber optic cable was laid on the seafloor over the northern part of the Juan de Fuca plate and connected to a shore facility near Port Alberni on Vancouver Island. In September 2009, three broadband OBS packages were deployed in the form of a large triangle with apexes at mid plate near ODP 1027 (water depth of 2654m) and two sites on the continental slope, near ODP 889 (1256m) and Barkley Canyon (396m). The broadband systems comprise a broadband seismometer and strong motion accelerometer in a spherical titanium case surficially buried in a caisson backfilled with glass beads. Noise levels observed are as expected with the spectra being similar to, or quieter than, coastal seismograph stations in approximately the 10 to 20 second period range. The OBS's have higher noise levels at longer periods where ocean swells and the resultant infragravity waves dominate the noise spectra, and in the 1-10 Hz bandwidth typically used for locating local earthquakes. The shallowest site at Barkley Canyon has the highest noise levels. A small array, about 6 km in maximum dimension, is under construction on the Endeavour segment of the Juan de Fuca Ridge to record earthquake activity in the vicinity of the many NEPTUNE Canada multi-disciplinary ridge experiments. Two short period instruments were installed there in 2010. A broadband instrument and two additional short period instruments are planned to complete the initial ridge array. Even though the NEPTUNE Canada seismograph network is not yet complete, measured by the use of its data, it is a success already. The data are routinely used along with data from land seismographs of the Canadian National Seismograph Network for locating earthquakes in the region. However, the smallest seismic arrivals picked on the land stations cannot be routinely picked on the OBS instruments due to the higher noise levels. Real-time data are also ingested by NOAA tsunami warning centers and researchers have accessed archived data to do such diverse things as track baleen whales, carry out receiver function analyses, and study microseismic noise. NEPTUNE Canada seismic data is freely available from IRIS.

78 FR 56829 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-09-16

... Minimums and ODP copies may be obtained from: 1. FAA Public Inquiry Center (APA-200), FAA Headquarters..., and the need for a special format make their verbatim publication in the Federal Register expensive...

77 FR 56762 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-09-14

... Minimums and ODP copies may be obtained from: 1. FAA Public Inquiry Center (APA-200), FAA Headquarters..., and the need for a special format make their verbatim publication in the Federal Register expensive...

Platinum Group Elements, 187OS/188OS and 87SR/86SR Isotope Systematics in Depleted Fluid-Modified Mariana Fore-Arc Peridotites

NASA Astrophysics Data System (ADS)

Harvey, J.; Savov, I. P.; Shirey, S. B.; Horan, M. F.; Mock, T. D.

2012-12-01

The serpentine mud volcanoes of the Izu-Bonin-Mariana (IBM) fore-arc, collected during Ocean Drilling Program Leg 195 [1], contain hard-rock clasts of serpentine sampled from close to the décollement, which separates the down-going Pacific slab from the overlying mantle wedge. These clasts preserve evidence for melt depletion (>25 % melt extraction in many instances) in a sub-arc environment, and extensive (40 - 100%) serpentinization due to subsequent fluid / peridotite interaction, e.g. [2]. Platinum-group element (PGE) abundances are not consistent with melt-depletion alone [3]. Fractionation between I-PGE (Os, Ir, Ru) has resulted in groups of IBM serpentinites with either a high chondrite-normalized Os/Ir ratio (OsN/IrN) or a low OsN/IrN ratio. Similarly, fractionation of P-PGE (Pt, Pd) is marked, and distinguishes the IBM serpentinites from worldwide abyssal peridotites. Interaction with high-pH fluids [4] may have partially oxidized mantle sulphide, the major primary host for PGE in these rocks, leading to partial breakdown to sulphate and the selective redistribution of certain PGE (Os, Ru, Pt), a feature normally associated with sub-aerial weathering [5], but which likely prevails in other oxidizing environments. In particular, the Re-Os systematics of the high (OsN/IrN) IBM serpentinites have been disturbed by the addition of Os. Unlike peridotite xenoliths associated with magmatic regions of subduction zones where subduction-related Os-addition is unequivocally radiogenic and derived from crustal material [6][7], where Os has been added to the IBM serpentinites it is unradiogenic and was most likely derived from within the oceanic mantle. IBM serpentinites therefore preserve osmium isotope ratios that are exclusively sub-chondritic (187Os/188Os ≤ 0.127), as previously reported [8]. These serpentinized peridotites were produced by at least a three-step process: melt depletion, serpentinization, and the mobilization of Os, Ru and Pt to produce low OsN/IrN "donor" and high OsN/IrN "recipient" serpentinites. The distinct chondrite normalized PGE patterns of the low OsN/IrN serpentinites are remarkably similar to those of back-arc basin basalts (BABB) from sites 291, 292, 444A, 450 drilled in the Philippine Sea Plate (PSP) during DSDP Legs 31, 58 and 59 [9]. [1] Fryer, et al. (1992) Proc. ODP Sci. Results 125, Fryer, P., Pearce, J. A., Stokking, L. B., et al., 373-385, Ocean Drilling Program, College Station TX, USA. [2] Savov et al. (2005) Geochem. Geophys. Geosyst. 6, Q04J15, doi:10.1029/2004GC000777 [3] Handler, & Bennett (1999) Geochim. Cosmochim. Acta 63, 3597-3618 [4] Mottl, M.J. (1992) Proc. ODP Sci. Results, 125, Fryer, P., Pearce, J. A., Stokking, L. B., et al., 373-385, Ocean Drilling Program, College Station TX, USA. [5] Lorand, et al. (2003) Geochim. Cosmochim. Acta 67, 4137-4151. [6] Brandon et al. (1999) Chem. Geol. 160, 387-407. [7] Widom et al. (2003) Chem. Geol. 196, 283- 306. [8] Parkinson et al. (1999) Science 281, 211-312 [9] Dale et al. (2008) Chem. Geol. 248, 213-238.

Volcanoclastics of the Walvis Ridge

NASA Astrophysics Data System (ADS)

Eroshenko, D. V.; Kharin, G. S.

2018-03-01

The paper generalizes the distribution of volcanoclastic material in the Cenozoic sedimentary cover of the Walvis Ridge, made on the basis of the DSDP (Deep Sea Drilling Projects) and ODP (Ocean Drilling Program). The cycles of volcanoclastic accumulation have been distinguished. It has been proved that the distribution of the material in the Paleogene primary reflects the dynamics of volcanism of the ridge itself. The sources of volcanoclastics have been determined. The possibility of the existence of Early Eocene submarine volcanoes in the central part of the ridge has been shown. The dynamics of volcanism of the ridge has been compared with the variability of major climatic markers in sediments, indicating the unity of volcanic processes in the region and processes that led to an increase in the index of 13C content in sediments and CO2 content in the atmosphere.

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

Chemistry, isotopic composition, and origin of a methane-hydrogen sulfide hydrate at the Cascadia subduction zone

USGS Publications Warehouse

Kastner, M.; Kvenvolden, K.A.; Lorenson, T.D.

1998-01-01

Although the presence of extensive gas hydrate on the Cascadia margin, offshore from the western U.S. and Canada, has been inferred from marine seismic records and pore water chemistry, solid gas hydrate has only been found at one location. At Ocean Drilling Program (ODP) Site 892, offshore from central Oregon, gas hydrate was recovered close to the sediment - water interface at 2-19 m below the seafloor, (mbsf) at 670 m water depth. The gas hydrate occurs as elongated platy crystals or crystal aggregates, mostly disseminated irregularly, with higher concentrations occurring in discrete zones, thin layers, and/or veinlets parallel or oblique to the bedding. A 2-to 3-cm thick massive gas hydrate layer, parallel to bedding, was recovered at ???17 mbsf. Gas from a sample of this layer was composed of both CH4 and H2S. This sample is the first mixed-gas hydrate of CH4-H2S documented in ODP; it also contains ethane and minor amounts of CO2. Measured temperature of the recovered core ranged from 2 to - 18??C and are 6 to 8 degrees lower than in-situ temperatures. These temperature anomalies were caused by the partial dissociation of the CH4-H2S hydrate during recovery without a pressure core sampler. During this dissociation, toxic levels of H2S (??34S, +27.4???) were released. The ??13C values of the CH4 in the gas hydrate, -64.5 to -67.5???(PDB), together with ??D values of - 197 to - 199???(SMOW) indicate a primarily microbial source for the CH4. The ??18O value of the hydrate H2O is +2.9???(SMOW), comparable with the experimental fractionation factor for sea-ice. The unusual composition (CH4-H2S) and depth distribution (2-19 mbsf) of this gas hydrate indicate mixing between a methane-rich fluid with a pore fluid enriched in sulfide; at this site the former is advecting along an inclined fault into the active sulfate reduction zone. The facts that the CH4-H2S hydrate is primarily confined to the present day active sulfate reduction zone (2-19 mbsf), and that from here down to the BSR depth (19-68 mbsf) the gas hydrate inferred to exist is a ???99% CH4 hydrate, suggest that the mixing of CH4 and H2S is a geologically young process. Because the existence of a mixed CH4-H2S hydrate is indicative of moderate to intense advection of a methane-rich fluid into a near surface active sulfate reduction zone, technically active (faulted) margins with organic-rich sediments and moderate to high sedimentation rates are the most likely regions of occurrence. The extension of such a mixed hydrate below the sulfate reduction zone should reflect the time-span of methane advection into the sulfate reduction zone. ?? 1998 Elsevier Science B.V. All rights reserved.

Broadband Seismic Observations at the Hawaii-2 Observatory During ODP Leg 200

NASA Astrophysics Data System (ADS)

Stephen, R. A.; Duennebier, F. K.; Harris, D.; Jolly, J.; Bolmer, S. T.; Bromirski, P. D.; Leg 200 Shipboard Scientific Party, .

2003-12-01

Ocean Drilling Project Leg 200 was the first leg in deep sea and ocean drilling history to conduct operations in the vicinity of a continuously operating broadband seafloor seismometer. In 1998 investigators from the University of Hawaii, Woods Hole Oceanographic Institution, and Incorporated Institutions for Seismology had installed a broadband, shallow buried seismometer at the site [Duennebier et al., 2002] and data has been acquired in real time in Oahu over the Hawaii-2 transoceanic cable. Hole 1224D was drilled, cased and cemented at the site so that a broadband borehole seismometer can be emplaced in the future. The noise from the JOIDES Resolution as it approached and left the site as well as during all on-site operations was observed. In addition we recorded shots with 80 cubic inch water guns during single channel seismic tests as well as whale songs and earthquake activity. The behavior of ambient noise levels near the microseism peak was also compared with local wind speed and sea state conditions as observed from the drill ship. This work was supported by a grant from JOI-USSAC. We would like to thank the Earthquake Research Institute at the University of Tokyo for a Visiting Professorship for RAS during which much of this work was carried out. [Duennebier, F.K., D.W. Harris, J. Jolly, J. Babinec, D. Copson, and K. Stiffel, The Hawaii-2 observatory seismic system, IEEE Journal of Oceanic Engineering, 27, 212-217, 2002.

Rare earth elements in Japan Sea sediments and diagenetic behavior of Ce/Ce∗: Results from ODP Leg 127

NASA Astrophysics Data System (ADS)

Murray, Richard W.; Buchholtzten Brink, Marilyn R.; Brumsack, Hans J.; Gerlach, David C.; Russ, G. Price

1991-09-01

The relative effects of paleoceanographic and paleogeographic variations, sediment lithology, and diagenetic processes on the recorded rare earth element (REE) chemistry of Japan Sea sediments are evaluated by investigating REE total abundances and relative fractionations in 59 samples from Ocean Drilling Program Leg 127. REE total abundances (ΣREE) in the Japan Sea are strongly dependent upon the paleoceanographic position of a given site with respect to terrigenous and biogenic sources. REE concentrations at Site 794 (Yamato Basin) overall correspond well to aluminosilicate chemical indices and are strongly diluted by SiO2 within the late Miocene-Pliocene diatomaceous sequence. Eu/Eu∗ values at Site 794 reach a maximum through the diatomaceous interval as well, most likely suggesting an association of Eu/Eu∗ with the siliceous component, or reflecting slight incorporation of a detrital feldspar phase. ΣREE at Site 795 (Japan Basin) also is affiliated strongly with aluminosilicate phases, yet is diluted only slightly by siliceous input. At Site 797 (Yamato Basin), REE is not as clearly associated with the aluminosilicate fraction, is correlated moderately to siliceous input, and may be sporadically influenced by detrital heavy minerals originating from the nearby rifted continental fragment composing the Yamato Rise. The biogenic influence is largest at Site 794, moderately developed at Site 797, and of only minor importance at Site 795, reflecting basinal contrasts in productivity such that the Yamato Basin records greater biogenic input than the Japan Basin, while the most productive waters overlie the easternmost sequence of Site 794. Ce/Ce∗ profiles at all three sites increase monotonically with depth, and record progressive diagenetic LREE fractionation. The observed Ce/Ce∗ record does not respond to changes in oxygenation state of the overlying water, and Ce/Ce∗ correlates slightly better with depth than with age. The downhole increase in Ce/Ce∗ at Site 794 and Site 797 is a passive response to diagenetic transfer of LREE (except Ce) from sediment to interstitial water. At Site 795, the overall lack of correlation between Ce/Ce∗ and Lan/Ybn suggests that other processes are occurring which mask the diagenetic behavior of all LREEs. First-order calculations of the Ce budget in Japan Sea waters and sediment indicate that ~20% of the excess Ce adsorbed by settling particles is recycled within the water column, and that an additional ~38% is recycled at or near the seafloor (data from MASUZAWA and KOYAMA, 1989). Thus, because the remaining excess Ce is only ~10% of the total Ce, there is not a large source of Ce to the deeply buried sediment, further suggesting that the downhole increase in Ce/Ce∗ is a passive response to diagenetic behavior of the other LREEs. The REE chemistry of Japan Sea sediment therefore predicts successive downhole addition of LREEs to deeply-buried interstitial waters.

40 CFR 63.459 - Alternative standards.

Code of Federal Regulations, 2012 CFR

2012-07-01

... wastewater treatment plant anaerobic basins for biodegradation. (iv) The pulping process condensates shall be... per ton of ODP by biodegradation in the wastewater treatment plant. (ii) The following calculation shall be performed to determine the HAP destruction efficiency by biodegradation in the wastewater...

40 CFR 63.459 - Alternative standards.

Code of Federal Regulations, 2014 CFR

2014-07-01

... wastewater treatment plant anaerobic basins for biodegradation. (iv) The pulping process condensates shall be... per ton of ODP by biodegradation in the wastewater treatment plant. (ii) The following calculation shall be performed to determine the HAP destruction efficiency by biodegradation in the wastewater...

40 CFR 63.459 - Alternative standards.

Code of Federal Regulations, 2013 CFR

2013-07-01

... wastewater treatment plant anaerobic basins for biodegradation. (iv) The pulping process condensates shall be... per ton of ODP by biodegradation in the wastewater treatment plant. (ii) The following calculation shall be performed to determine the HAP destruction efficiency by biodegradation in the wastewater...

40 CFR 63.459 - Alternative standards.

Code of Federal Regulations, 2010 CFR

2010-07-01

... wastewater treatment plant anaerobic basins for biodegradation. (iv) The pulping process condensates shall be... per ton of ODP by biodegradation in the wastewater treatment plant. (ii) The following calculation shall be performed to determine the HAP destruction efficiency by biodegradation in the wastewater...

40 CFR 63.459 - Alternative standards.

Code of Federal Regulations, 2011 CFR

2011-07-01

... wastewater treatment plant anaerobic basins for biodegradation. (iv) The pulping process condensates shall be... per ton of ODP by biodegradation in the wastewater treatment plant. (ii) The following calculation shall be performed to determine the HAP destruction efficiency by biodegradation in the wastewater...

77 FR 37799 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-25

..., individual SIAP and Takeoff Minimums and ODP copies may be obtained from: 1. FAA Public Inquiry Center (APA... number of SIAPs, their complex nature, and the need for a special format make their verbatim publication...

77 FR 5694 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-06

... Minimums and ODP copies may be obtained from: 1. FAA Public Inquiry Center (APA-200), FAA Headquarters..., their complex nature, and the need for a special format make their verbatim publication in the Federal...

MapApp: A Java(TM) Applet for Accessing Geographic Databases

NASA Astrophysics Data System (ADS)

Haxby, W.; Carbotte, S.; Ryan, W. B.; OHara, S.

2001-12-01

MapApp (http://coast.ldeo.columbia.edu/help/MapApp.html) is a prototype Java(TM) applet that is intended to give easy and versatile access to geographic data sets through a web browser. It was developed initially to interface with the RIDGE Multibeam Synthesis. Subsequently, interfaces with other geophysical databases were added. At present, multibeam bathymetry grids, underway geophysics along ship tracks, and the LDEO Borehole Research Group's ODP well logging database are accessible through MapApp. We plan to add an interface with the Ridge Petrology Database in the near future. The central component of MapApp is a world physiographic map. Users may navigate around the map (zoom/pan) without waiting for HTTP requests to a remote server to be processed. A focus request loads image tiles from the server to compose a new map at the current viewing resolution. Areas in which multibeam grids are available may be focused to a pixel resolution of about 200 m. These areas may be identified by toggling a mask. Databases may be accessed through menus, and selected data objects may be loaded into MapApp by selecting items from tables. Once loaded, a bathymetry grid may be contoured or used to create bathymetric profiles; ship tracks and ODP sites may be overlain on the map and their geophysical data plotted in X-Y graphs. The advantage of applets over traditional web pages is that they permit dynamic interaction with data sets, while limiting time consuming interaction with a remote server. Users may customize the graphics display by modifying the scale, or the symbol or line characteristics of rendered data, contour interval, etc. The ease with which users can select areas, view the physiography of areas, and preview data sets and evaluate them for quality and applicability, makes MapApp a valuable tool for education and research.

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.

Novel Degenerate PCR Method for Whole-Genome Amplification Applied to Peru Margin (ODP Leg 201) Subsurface Samples

PubMed Central

Martino, Amanda J.; Rhodes, Matthew E.; Biddle, Jennifer F.; Brandt, Leah D.; Tomsho, Lynn P.; House, Christopher H.

2011-01-01

A degenerate polymerase chain reaction (PCR)-based method of whole-genome amplification, designed to work fluidly with 454 sequencing technology, was developed and tested for use on deep marine subsurface DNA samples. While optimized here for use with Roche 454 technology, the general framework presented may be applicable to other next generation sequencing systems as well (e.g., Illumina, Ion Torrent). The method, which we have called random amplification metagenomic PCR (RAMP), involves the use of specific primers from Roche 454 amplicon sequencing, modified by the addition of a degenerate region at the 3′ end. It utilizes a PCR reaction, which resulted in no amplification from blanks, even after 50 cycles of PCR. After efforts to optimize experimental conditions, the method was tested with DNA extracted from cultured E. coli cells, and genome coverage was estimated after sequencing on three different occasions. Coverage did not vary greatly with the different experimental conditions tested, and was around 62% with a sequencing effort equivalent to a theoretical genome coverage of 14.10×. The GC content of the sequenced amplification product was within 2% of the predicted values for this strain of E. coli. The method was also applied to DNA extracted from marine subsurface samples from ODP Leg 201 site 1229 (Peru Margin), and results of a taxonomic analysis revealed microbial communities dominated by Proteobacteria, Chloroflexi, Firmicutes, Euryarchaeota, and Crenarchaeota, among others. These results were similar to those obtained previously for those samples; however, variations in the proportions of taxa identified illustrates well the generally accepted view that community analysis is sensitive to both the amplification technique used and the method of assigning sequences to taxonomic groups. Overall, we find that RAMP represents a valid methodology for amplifying metagenomes from low-biomass samples. PMID:22319519

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.

Lineage-specific evolution of the vertebrate Otopetrin gene family revealed by comparative genomic analyses

PubMed Central

2011-01-01

Background Mutations in the Otopetrin 1 gene (Otop1) in mice and fish produce an unusual bilateral vestibular pathology that involves the absence of otoconia without hearing impairment. The encoded protein, Otop1, is the only functionally characterized member of the Otopetrin Domain Protein (ODP) family; the extended sequence and structural preservation of ODP proteins in metazoans suggest a conserved functional role. Here, we use the tools of sequence- and cytogenetic-based comparative genomics to study the Otop1 and the Otop2-Otop3 genes and to establish their genomic context in 25 vertebrates. We extend our evolutionary study to include the gene mutated in Usher syndrome (USH) subtype 1G (Ush1g), both because of the head-to-tail clustering of Ush1g with Otop2 and because Otop1 and Ush1g mutations result in inner ear phenotypes. Results We established that OTOP1 is the boundary gene of an inversion polymorphism on human chromosome 4p16 that originated in the common human-chimpanzee lineage more than 6 million years ago. Other lineage-specific evolutionary events included a three-fold expansion of the Otop genes in Xenopus tropicalis and of Ush1g in teleostei fish. The tight physical linkage between Otop2 and Ush1g is conserved in all vertebrates. To further understand the functional organization of the Ushg1-Otop2 locus, we deduced a putative map of binding sites for CCCTC-binding factor (CTCF), a mammalian insulator transcription factor, from genome-wide chromatin immunoprecipitation-sequencing (ChIP-seq) data in mouse and human embryonic stem (ES) cells combined with detection of CTCF-binding motifs. Conclusions The results presented here clarify the evolutionary history of the vertebrate Otop and Ush1g families, and establish a framework for studying the possible interaction(s) of Ush1g and Otop in developmental pathways. PMID:21261979

A major change in North Atlantic deep water circulation during the Early Pleistocene transition 1.6 million years ago

NASA Astrophysics Data System (ADS)

Khélifi, N.; Frank, M.

2013-12-01

The global ocean-climate system has been highly sensitive to the formation and advection of deep water in the North Atlantic but its evolution over the Pliocene-Pleistocene global cooling is not fully understood. In particular, changes in the sources and mixing of prevailing deep waters are not well constrained. Here we present new records of the bottom-water radiogenic neodymium isotope (ϵNd) variability obtained from three DSDP/ODP sites at water depths between 2100 and 5000 m in the Northeast Atlantic to reconstruct changes in deep water circulation over the past 4 million years. Prior to 1.6 million years ago (Ma), we find ϵNd values primarily oscillating between -9 and -11 at all sites, consistent with enhanced vertical mixing of water masses. At 1.6 Ma, the ϵNd signatures synchronously shifted to less radiogenic values around -12 at different water depths and water mass signatures gradually became more distinct. Since then values and amplitudes of "glacial/interglacial" ϵNd oscillations have been similar to the Late Quaternary at each site. This change 1.6 Ma reflects a major reorganization of deep water circulation in the Northeast Atlantic towards a more stratified water column with distinct water masses accompanying the enhanced response of climate to the Earth's obliquity forcing during the Early Pleistocene transition.

Statistical Features of Deep-ocean Tsunamis Based on 30 Years of Bottom Pressure Observations in the Northeast Pacific

NASA Astrophysics Data System (ADS)

Fine, I.; Thomson, R.; Chadwick, W. W., Jr.; Davis, E. E.; Fox, C. G.

2016-12-01

We have used a set of high-resolution bottom pressure recorder (BPR) time series collected at Axial Seamount on the Juan de Fuca Ridge beginning in 1986 to examine tsunami waves of seismological origin in the northeast Pacific. These data are a combination of autonomous, internally-recording battery-powered instruments and cabled instruments on the OOI Cabled Array. Of the total of 120 tsunami events catalogued for the coasts of Japan, Alaska, western North America and Hawaii, we found evidence for 38 events in the Axial Seamount BPR records. Many of these tsunamis were not observed along the adjacent west coast of the USA and Canada because of the much higher noise level of coastal locations and the lack of digital tide gauge data prior to 2000. We have also identified several tsunamis of apparent seismological origin that were observed at coastal stations but not at the deep ocean site. Careful analysis of these observations suggests that they were likely of meteorological origin. Analysis of the pressure measurements from Axial Seamount, along with BPR measurements from a nearby ODP CORK (Ocean Drilling Program Circulation Obviation Retrofit Kit) borehole and DART (Deep-ocean Assessment and Reporting of Tsunamis) locations, reveals features of deep-ocean tsunamis that are markedly different from features observed at coastal locations. Results also show that the energy of deep-ocean tsunamis can differ significantly among the three sets of stations despite their close spatial spacing and that this difference is strongly dependent on the direction of the incoming tsunami waves. These deep-ocean observations provide the most comprehensive statistics possible for tsunamis in the Pacific Ocean over the past 30 years. New insight into the distribution of tsunami amplitudes and wave energy derived from the deep-ocean sites should prove useful for long-term tsunami prediction and mitigation for coastal communities along the west coast of the USA and Canada.

Flow, stock, and impact assessment of refrigerants in the Japanese household air conditioner sector.

PubMed

Xue, Mianqiang; Kojima, Naoya; Machimura, Takashi; Tokai, Akihiro

2017-05-15

Refrigerants provide society with great benefits while have the potential to cause adverse effects on the environment and human health. The present study estimated time-dependent flows and stocks and assessed the effects of refrigerants (R-22, R-410a, and R-32) in household air conditioners in Japan. It was found that stock of R-22 and R-410a peaked at 49,147t in 2000 and 55,994t in 2017, respectively. The largest flow of R-22 and R-410a to waste phase occurred at 3417t/yr. in 2005 and 4011t/yr. in 2023, respectively. The total global warming potential (GWP) due to refrigerant emissions increased from 3.6kt CO 2 eq. in 1952 to 6999kt CO 2 eq. in 2019, and then decreased to 5314kt CO 2 eq. in 2030. The ozone depletion potential (ODP) peaked at 141t CFC-11 eq. in 2002. When substituting R-410a for R-22, the ODP decreased 50% while the GDP increased 8%. When substituting R-32 for R-410a, there was no effect on the ODP while the GDP decreased 6%. The human health damage due to the global warming effect of refrigerant emission was much higher than that due to the ozone depleting effect. The refrigerant emission in use and waste management phases dominated the human health damage. The dynamic estimation not only allows us to evaluate the performance of past policies but also supports the future sustainable management associated with the health effects of refrigerants. Copyright © 2017 Elsevier B.V. All rights reserved.

Comparison of Perioperative Outcomes between Open, Laparoscopic, and Robotic Distal Pancreatectomy: an Analysis of 1815 Patients from the ACS-NSQIP Procedure-Targeted Pancreatectomy Database.

PubMed

Xourafas, Dimitrios; Ashley, Stanley W; Clancy, Thomas E

2017-09-01

Robotic surgery is gaining acceptance for distal pancreatectomy (DP). Nevertheless, no multi-institutional data exist to demonstrate the ideal clinical circumstances for use and the efficacy of the robot compared to the open or laparoscopic techniques, in terms of perioperative outcomes. The 2014 ACS-NSQIP procedure-targeted pancreatectomy data for patients undergoing DP were analyzed. Demographics and clinicopathological and perioperative variables were compared between the three approaches. Univariate and multivariable analyses were used to evaluate outcomes. One thousand eight hundred fifteen DPs comprised 921 open distal pancreatectomies (ODPs), 694 laparoscopic distal pancreatectomies (LDPs), and 200 robotic distal pancreatectomies (RDPs). The three groups were comparable with respect to demographics, ASA score, relevant comorbidities, and malignant histology subtype. Compared to the ODP group, patients undergoing RDP had lower T-stages of disease (P = 0.0192), longer operations (P = 0.0030), shorter hospital stays (P < 0.0001), and lower postoperative 30-day morbidity (P = 0.0476). Compared to the LDP group, RDPs were longer operations (P < 0.0001) but required fewer concomitant vascular resections (P = 0.0487) and conversions to open surgery (P = 0.0068). On multivariable analysis, neoadjuvant therapy (P = 0.0236), malignant histology (P = 0.0124), pancreatic reconstruction (P = 0.0006), and vascular resection (P = 0.0008) were the strongest predictors of performing an ODP. The open, laparoscopic, and robotic approaches to distal pancreatectomy offer particular advantages for well-selected patients and specific clinicopathological contexts; therefore, clearly demonstrating the most suitable use and superiority of one technique over another remains challenging.

Proposal of Environmental Impact Assessment Method for Concrete in South Korea: An Application in LCA (Life Cycle Assessment)

PubMed Central

Kim, Tae Hyoung; Tae, Sung Ho

2016-01-01

This study aims to develop a system for assessing the impact of the substances discharged from concrete production process on six environmental impact categories, i.e., global warming (GWP), acidification (AP), eutrophication (EP), abiotic depletion (ADP), ozone depletion (ODP), and photochemical oxidant creation (POCP), using the life a cycle assessment (LCA) method. To achieve this, this study proposed an LCA method specifically applicable to the Korean concrete industry by adapting the ISO standards to suit the Korean situations. The proposed LCA method involves a system that performs environmental impact assessment on the basis of input information on concrete mix design, transport distance, and energy consumption in a batch plant. The Concrete Lifecycle Assessment System (CLAS) thus developed provides user-friendly support for environmental impact assessment with specialized database for concrete mix materials and energy sources. In the case analysis using the CLAS, among the substances discharged from the production of 24 MPa concrete, those contributing to GWP, AP, EP, ADP, ODP, and POCP were assessed to amount to 309 kg-CO2 eq/m3, 28.7 kg-SO2 eq/m3, 5.21 kg-PO43− eq/m3, 0.000049 kg-CFC11 eq/m3, 34 kg/m3, and 21 kg-Ethylene eq/m3, respectively. Of these six environmental impact categories selected for the LCA in this study, ordinary Portland cement (OPC) was found to contribute most intensely to GWP and POCP, and aggregates, to AP, EP, ODP, and ADP. It was also found that the mix design with increased prop proportion of recycled aggregate was found to contribute to reducing the impact in all other categories. PMID:27827843

Optical coherence tomography in optic pit maculopathy managed with vitrectomy-laser-gas.

PubMed

García-Arumí, José; Guraya, Borja Corcóstegui; Espax, Ana Boixadera; Castillo, Vicente Martínez; Ramsay, Laura Sararols; Motta, R Max

2004-10-01

Optic disc pit (ODP) maculopathy has a poor visual prognosis if left to its natural course. Several therapeutic approaches have been attempted. The cases of 11 patients evaluated with optical coherence tomography (OCT) and treated with vitrectomy-laser-gas and their functional and anatomical outcomes are presented. Retrospective interventional consecutive case series, including 11 eyes with ODP maculopathy. Pre- and postoperative best-corrected visual acuity (BCVA), OCT and angiography were recorded. All patients underwent pars plana vitrectomy, posterior hyaloid dissection peripapillary diode laser prior to retinal reapplication and C(3)F(8) 15% injection. Mean preoperative BCVA was 20/126. Median preoperative BCVA was 1.0 LogMAR (range 1.3-0.4) . Eighty-two per cent of patients gained 2 or more Snellen lines of vision (mean 4.4 lines gained). Mean final BCVA was 20/32, and median final BCVA was 20/30 in Snellen VA and 0.2 in LogMAR (range 0.7-0) Preoperative OCT in all but one case confirmed the bilaminar structure of the macular detachment. Postoperative OCT helped in monitoring reabsorption of the macular detachment, which was achieved in all cases after an average of 6.5 months post-surgery. BCVA increased progressively as the subretinal fluid was reabsorbed (P=0.006). Mean duration of postoperative follow-up was 15 months. Recurrence was observed in two cases. In our series, the vitrectomy-laser-gas procedure for ODP maculopathy improved vision and achieved satisfactory anatomic results in all 11 cases. OCT was useful in the diagnosis and follow-up of this pathology. However, the low incidence of this entity makes it difficult to obtain series large enough to determine the efficacy of the vitrectomy-laser-gas procedure and other treatment modalities and be able to suggest a procedure of choice.

Proposal of Environmental Impact Assessment Method for Concrete in South Korea: An Application in LCA (Life Cycle Assessment).

PubMed

Kim, Tae Hyoung; Tae, Sung Ho

2016-11-02

This study aims to develop a system for assessing the impact of the substances discharged from concrete production process on six environmental impact categories, i.e., global warming (GWP), acidification (AP), eutrophication (EP), abiotic depletion (ADP), ozone depletion (ODP), and photochemical oxidant creation (POCP), using the life a cycle assessment (LCA) method. To achieve this, this study proposed an LCA method specifically applicable to the Korean concrete industry by adapting the ISO standards to suit the Korean situations. The proposed LCA method involves a system that performs environmental impact assessment on the basis of input information on concrete mix design, transport distance, and energy consumption in a batch plant. The Concrete Lifecycle Assessment System (CLAS) thus developed provides user-friendly support for environmental impact assessment with specialized database for concrete mix materials and energy sources. In the case analysis using the CLAS, among the substances discharged from the production of 24 MPa concrete, those contributing to GWP, AP, EP, ADP, ODP, and POCP were assessed to amount to 309 kg-CO₂ eq/m³, 28.7 kg-SO₂ eq/m³, 5.21 kg-PO₄ 3- eq/m³, 0.000049 kg-CFC 11 eq/m³, 34 kg/m³, and 21 kg-Ethylene eq/m³, respectively. Of these six environmental impact categories selected for the LCA in this study, ordinary Portland cement (OPC) was found to contribute most intensely to GWP and POCP, and aggregates, to AP, EP, ODP, and ADP. It was also found that the mix design with increased prop proportion of recycled aggregate was found to contribute to reducing the impact in all other categories.

Development of mass production type rigid polyurethane foam for LNG carrier using ozone depletion free blowing agent

NASA Astrophysics Data System (ADS)

Lee, Yeongbeom; Baek, Kye Hyun; Choe, Kunhyung; Han, Chonghun

2016-12-01

Nowadays the price of natural gas has become higher and the efficiency of propulsion system of liquefied natural gas (LNG) carriers has improved. Due to these trends, required boil-off rate (BOR) for LNG carrier has been lowered from 0.15%/day to 0.12%/day for conventional LNG carriers with sizes between 125,000 m3 and 170,000 m3. This requirement of BOR can be satisfied by using a rigid polyurethane foam (PUF) blown by 1,1-dichloro-1-fluoroethane (HCFC-141b) as an insulator. However, ozone depletion potential (ODP) of HCFC-141b requires alternative blowing agents with zero ODP such as hydroflurocarbons (HFCs) because of tougher environmental regulations. This paper introduces use of HFCs and additives to enhance properties of rigid PUFs under a mass production environment. Among the additives, perfluoroalkane (PFA) reduces thermal conductivity down to 12% and increases compressive strength up to 15% of a rigid PUF prepared in a laboratory scale. Based on this result, a mass production type rigid PUF is manufactured and is evaluated for BOR, mechanical strengths over operation temperature range, and thermal shock stability for LNG carriers. The BOR of the manufactured rigid PUF is below 0.12%/day, which satisfies the recent BOR specification for LNG carriers. The other required properties are also met the specifications for a conventional LNG carrier. Consequently, it is expected that the results in this paper will bring low BOR (<0.12%/day) LNG carries with rigid PUFs using ODP free blowing agents and contribute environmental protection through saving energy and preserving the ozone layer in the stratosphere.

Chilean and Southeast Pacific paleoclimate variations during the last glacial cycle: directly correlated pollen and δ18O records from ODP Site 1234

NASA Astrophysics Data System (ADS)

Heusser, Linda; Heusser, Cal; Mix, Alan; McManus, Jerry

2006-12-01

Joint pollen and oxygen isotope data from Ocean Drilling Program Site 1234 in the southeast Pacific provide the first, continuous record of temperate South American vegetation and climate from the last 140 ka. Located at ˜36°S, ˜65 km offshore of Concepcion, Chile, Site 1234 monitors the climatic transition zone between northern semi-arid, summer dry-winter wet climate and southern year-round, rainy, cool temperate climate. Dominance of onshore winds suggests that pollen preserved here reflects transport to the ocean via rivers that drain the region and integrate conditions from the coastal mountains to the Andean foothills. Down-hole changes in diagnostic pollen assemblages from xeric lowland deciduous forest (characterized by grasses, herbs, ferns, and trees such as deciduous beech, Nothofagus obliqua), mesic Valdivian Evergreen Forest (including conifers such as the endangered Prumnopitys andina), and Subantarctic Evergreen Rainforest (comprised primarily of southern beech, N. dombeyi) reveal large rapid shifts that likely reflect latitudinal movements in atmospheric circulation and storm tracks associated with the southern westerly winds. During glacial intervals (MIS 2-4, and 6), rainforests and parkland dominated by Nothofagus moved northward into the region. At the MIS 6/5e transition, coeval with the rapid shift to lower isotopic values, rainforest vegetation was rapidly replaced by xeric plant communities associated with Mediterranean-type climate. An increased prominence of halophytic vegetation suggests that MIS 5e was more arid and possibly warmer than MIS 1. Although rainforest pollen rises again at the end of MIS 5e, lowland deciduous forest pollen persists through MIS 5d and 5c, into MIS 5b. Substantial millennial-scale variations occur in both interglacial and glacial regimes, attesting to the sensitivity of the southern westerly belt to climate change. Comparison of the cool, mesic N. dombeyi rainforest assemblage from Site 1234 with δ18O in the Byrd Ice core shows that on time scales longer than ˜10 ka, cool-moist conditions in central Chile were coherent with and occurred in phase with Antarctic cooling. This is also likely at millennial scales, although rainforest pollen lags Antarctic cooling with exponential response times of about 1000 years, which plausibly reflects the ecological response time to regional climate change.

The Importance of Actualistic Source-to-Sink Sand Provenance Studies in Illuminating the Nature of Ancient Fluvial Systems From the Deep-Marine Clastic Successions They Sourced

NASA Astrophysics Data System (ADS)

Marsaglia, K. M.; Parra, J. G.; Dawson, S.

2006-12-01

Successions of gravity-flow deposits in deep-marine fan systems have the potential to record the evolution of their fluvial source region as well as specific tectonic, climatic, eustatic and anthropogenic events. Deciphering these signals involves the description and quantification of key sediment attributes such as fan volume, the rate of sediment accumulation, the frequency of depositional events, sediment texture, and sediment composition. Sediment composition/provenance provides insight into the nature of the fluvial source, including drainage basin geology and drainage development. For example, Marsaglia et al. (1995) demonstrated a connection between source river lengthening owing to eustatic change and sand composition in Quaternary turbidite successions of the Santa Barbara Basin at Ocean Drilling Program (ODP) Site 893. In contrast, longer-term compositional trends recognized in the Mesozoic to Cenozoic rift-to-drift successions cored by various ODP legs on the North Atlantic margins are more likely associated with continental margin drainage development and fluvial system evolution (Marsaglia et al., in press). These two connections between sink and source were made possible by well-documented petrologic data sets for both modern onshore fluvial systems and older offshore deep-marine successions, but in each case different workers collected the onshore and offshore data sets. In the Waipaoa River Sedimentary System of North Island, New Zealand we have taken a different, more holistic approach, with a limited and linked group of researchers and sample data base covering the complete system. The study area is an active forearc margin characterized by uplifted and deformed sedimentary successions and periodic input of arc-derived ash. Recently, the modern onshore system has been thoroughly documented via studies of the petrology of outcropping Mesozoic to Cenozoic units, fluvial terrace deposits, and modern fluvial sediments (e.g., James et al., in press). Now we are building on that data set and moving from source-to-sink to trace sandy sediment through the system out onto the shelf and slope where it has been encountered in shallow cores. Lessons learned onshore, such as a distinct compositional dependence on grain size and the relationships of bedrock geology to certain sand grain types, also apply to these offshore core samples. Many of the sandy intervals are largely composed of reworked tephra from Taupo eruptions, whereas quartz and feldspar dominate finer sand samples. Lithic-dominated sands are less common and coarser grained. Isolated greywacke gravel clasts indicate that at some point coarse sediment "leaked" into the basin from the south. The volumetric importance of this extrabasinal input can be assessed by looking at the types and proportions of lithic fragments within the finer sand fraction.

Ontology Design Patterns as Interfaces (invited)

NASA Astrophysics Data System (ADS)

Janowicz, K.

2015-12-01

In recent years ontology design patterns (ODP) have gained popularity among knowledge engineers. ODPs are modular but self-contained building blocks that are reusable and extendible. They minimize the amount of ontological commitments and thereby are easier to integrate than large monolithic ontologies. Typically, patterns are not directly used to annotate data or to model certain domain problems but are combined and extended to form data and purpose-driven local ontologies that serve the needs of specific applications or communities. By relying on a common set of patterns these local ontologies can be aligned to improve interoperability and enable federated queries without enforcing a top-down model of the domain. In previous work, we introduced ontological views as layer on top of ontology design patterns to ease the reuse, combination, and integration of patterns. While the literature distinguishes multiple types of patterns, e.g., content patterns or logical patterns, we propose to use them as interfaces here to guide the development of ontology-driven systems.

Widespread Neogene and Quaternary Volcanism on Central Kerguelen Plateau, Southern Indian Ocean

NASA Astrophysics Data System (ADS)

Duncan, R. A.; Falloon, T.; Quilty, P. G.; Coffin, M. F.

2016-12-01

We report new age determinations and compositions for rocks from 18 dredge hauls collected from eight submarine areas across Central Kerguelen Plateau (CKP). Sea knolls and volcanic fields with multiple small cones were targeted over a 125,000 km2 region that includes Heard and McDonald islands. Large early Miocene (16-22 Ma) sea knolls rise from the western margin of the CKP and are part of a NNW-SSE line of volcanic centers that lie between Îles Kerguelen and Heard and McDonald islands. A second group of large sea knolls is aligned E-W across the center of this region. We see evidence of much younger activity (5 Ma to present) in volcanic fields to the north of, and up to 300 km NE of Heard Island. Compositions include basanite, basalt, and trachybasalt, that are broadly similar to plateau lava flows from nearby Ocean Drilling Program (ODP) Site 1138, lower Miocene lavas at Îles Kerguelen, dredged rocks from the early Miocene sea knolls, and Big Ben lavas from Heard Island. Geochemical data indicate decreasing fractions of mantle source melting with time. The western line of sea knolls has been related to hotspot activity now underlying the Heard Island area. In view of the now recognized much larger area of young volcanic activity, we propose that a broad region of CKP became volcanically active in Neogene time due to incubation of plume material at the base of the relatively stationary overlying plateau. The presence of pre-existing crustal faults promotes access for melts from the Heard mantle plume to rise to the surface.

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.

Tracing late Quaternary tropical wetland dynamics in the Congo catchment using microbial biomarker records from deep sea fan sediments

NASA Astrophysics Data System (ADS)

Spencer-Jones, Charlotte Louise; Schefuβ, Enno; Wagner, Thomas; Handley, Luke; Talbot, Helen Marie

2014-05-01

Methane is a climatically active gas with a global warming potential 72 time that of CO2 over 20 years. Release of methane into the atmosphere has been suggested as a potential source of warming in palaeoclimate studies. This has implications for future climate as increased global temperatures could destabilise sources of sedimentary methane releasing it to the atmosphere. It is therefore important to establish the possible sinks of methane that could attenuate methane emissions. We present a high resolution record from the Congo deep sea fan (ODP 1075) of amino-bacteriohopanepolyols (amino-BHPs). The methanotrophic source of aminopentol, a biomarker for aerobic methane oxidation (AMO), in ODP 1075 is supported by compound specific δ13C isotope values of -41‰ for aminopentol precursors. High resolution intervals of isotope stages 10 to 13 (~500 to ~400 kyrs BP) confirm aminopentol to vary on glacial-interglacial timescales. High concentrations of amino-BHPs are recorded during warm, interglacial stages 11 and 13 with low concentrations of amino-BHPs during cold, glacial stages 10 and 12. This increase in AMO intensity (as suggested by aminopentol concentrations) during stages 11 and 13 is likely an imported signature from the Congo hinterland. Sediments analysed for amino-BHPs from floodplain wetlands show similar biomarker signatures as the marine sediments, suggesting a common source. Wetlands are important and widespread sub-environments in all large tropical river catchments. Their extent responds to fluctuations in humidity, which changes at glacial-interglacial and shorter time scales in response to the level of humidity. Humidity in the interior of tropical Africa has been shown to be driven by fluctuations in the difference in sea surface temperature (SST) between the subtropical and tropical South Atlantic (Schefuss et al., 2004). D-SST profiles based on UK 37 from the Angola (ODP 1082) and Congo basins (ODP 1077, Geob 1082) show an inverse relationship with amino-BHP profiles with minimum Delta-SST values coinciding high amino-BHP concentrations. Therefore periods of high humidity (as inferred from minimum Delta-SST) coincide with periods of intense AMO biomarker production and export, supporting the novel approach to use amino BHPs in marine sediments to reconstruct tropical wetland dynamics in the past. Schefuss, E., Damste, J.S.S., Jansen, J.H.F., 2004. Forcing of tropical Atlantic sea surface temperatures during the mid-Pleistocene transition. Paleoceanography 19.

The diagenetic fate of taraxer-14-ene and oleanene isomers

NASA Astrophysics Data System (ADS)

ten Haven, H. L.; Rullkötter, J.

1988-10-01

The extractable organic matter in Holocene to early Miocene deep-sea sediments from Site 645 (ODP Leg 105) in Baffin Bay contains almost exclusively biological markers of terrigenous origin. Pentacyclic triterpenoids of the α-(ursene) and β-amyrin (oleanene) type often occur as the most abundant compounds in the aliphatic hydrocarbon, ketone and alcohol fractions of the sediment extract. A specific diagenetic reaction involves the conversion of taraxer-14-ene into olean-12-ene in the upper 700 metres of the sedimentary sequence. The taraxerene-to-oleanene conversion is complete before the onset of isomerisation of diasterenes at C-20. In the sediment as well as in laboratory simulation experiments, olean-12-ene further isomerises to olean-13(18)-ene and olean-18-ene, the latter of which may be the direct precursor of 18β(H)- and 18α(H)-oleanane found in sediments containing more mature organic matter and in crude oils. The subsurface interconversion of these triterpenoid skeletons indicate that oleanane does not necessarily start life as an oleanoid.

Ocean export production and foraminiferal stable isotopes in the Antarctic Southern Ocean across the mid-Pleistocene transition

NASA Astrophysics Data System (ADS)

Hasenfratz, A. P.; Martinez-Garcia, A.; Jaccard, S.; Hodell, D. A.; Vance, D.; Bernasconi, S. M.; Greaves, M.; Haug, G. H.

2014-12-01

Changes in buoyancy forcing in the Antarctic Zone (AZ) of the Southern Ocean are believed to play an instrumental role in modulating atmospheric CO2 concentrations during glacial cycles by regulating the transfer of carbon between the ocean interior and the atmosphere. Indeed, a million-year-spanning high-resolution excess Barium record from the AZ of the South Atlantic (ODP 1094), which traces changes in export production, shows decreased export production during cold periods suggesting decreased overturning. Here, we extend this AZ export production record back to 1.6 Myr. In addition, we present new carbon and oxygen isotope records of benthic and planktic foraminifera from the same site, complemented by Mg/Ca measurements in some intervals. The interpretation of these new data in the context of other South Atlantic records contributes to a better understanding of Southern Ocean hydrography and its role in modulating glacial/interglacial cycles over the past 1.6 Myr.

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.

Characterising Atlantic deep waters during the extreme warmth of the early Eocene 'greenhouse'.

NASA Astrophysics Data System (ADS)

Cameron, A.; Sexton, P. F.; Anand, P.; Huck, C. E.; Fehr, M.; Dickson, A.; Scher, H. D.; van de Flierdt, T.; Westerhold, T.; Roehl, U.

2014-12-01

The meridional overturning circulation (MOC) is a planetary-scale oceanic flow that is of direct importance to the climate system because it transports heat, salt and nutrients to high latitudes and regulates the exchange of CO2 with the atmosphere. The Atlantic Ocean plays a strong role in the modern day MOC however, it is unclear what role it may have played during extreme climate conditions such as those found in the early Eocene 'greenhouse'. In order to resolve the Atlantic's role in the MOC during the early/middle Eocene, we present a multi-proxy approach to investigate changes in ocean circulation, water mass geometry, sediment supply to the deep oceans and the physical strength of deep waters from four different IODP drill sites. Neodymium isotopes (ɛNd), REE profiles and cerium anomalies measured in fossilised fish teeth help to characterise geochemical changes to water masses throughout the Atlantic whilst bulk sediment ɛNd and XRF-core scan data documents changes in sediment supply to the region. Sortable silt data provides a physical constraint on the strength of deep-water movements during the extreme climatic conditions of the early Eocene. We utilise expanded and continuous sequences from two sites in the North west Atlantic spanning the early to middle Eocene recently recovered on IODP Exp. 342 (1403, 1409) that are located on the Newfoundland Ridge, directly in the flow path of today's Deep Western Boundary Current. We also present data from equatorial Demerara Rise (IODP site 1258) and from further north at the mouth of the Labrador Sea (ODP Site 647).

78 FR 78071 - Protection of Stratospheric Ozone: Adjustments to the Allowance System for Controlling HCFC...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-12-24

... an individual consumption baseline year to each company by selecting its highest ODP-weighted... 2003-2009 regulatory period, using each company's highest ``production year'' or ``consumption year... 605 based on an EPA determination regarding current scientific information or the availability of...

40 CFR 63.457 - Test methods and procedures.

Code of Federal Regulations, 2011 CFR

2011-07-01

... port locations and gas stream properties. For purposes of selecting vent sampling port locations and... sampling line into the stack and secure it with the tip slightly lower than the port height. Start the pump... ketone, and propionaldehyde mass flow rates (kg/Mg ODP) entering the biological treatment system...

40 CFR 63.457 - Test methods and procedures.

Code of Federal Regulations, 2010 CFR

2010-07-01

... port locations and gas stream properties. For purposes of selecting vent sampling port locations and... sampling line into the stack and secure it with the tip slightly lower than the port height. Start the pump... ketone, and propionaldehyde mass flow rates (kg/Mg ODP) entering the biological treatment system...

77 FR 237 - Protection of Stratospheric Ozone: Adjustments to the Allowance System for Controlling HCFC...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-01-04

..., Heating, and Air-Conditioning Contractors (NAICS code 238220), including Central air-conditioning system and commercial refrigeration installation; HVAC contractors. This list is not intended to be... selecting its highest ODP- weighted consumption year from among the years 1994 through 1997. [[Page 241...

40 CFR 63.446 - Standards for kraft pulping process condensates.

Code of Federal Regulations, 2013 CFR

2013-07-01

... pulp products, owners and operators may meet a prorated mass standard that is calculated by prorating the applicable mass standards (kilograms of total HAP per megagram of ODP) for bleached and unbleached... 40 Protection of Environment 10 2013-07-01 2013-07-01 false Standards for kraft pulping process...

40 CFR 63.446 - Standards for kraft pulping process condensates.

Code of Federal Regulations, 2014 CFR

2014-07-01

... pulp products, owners and operators may meet a prorated mass standard that is calculated by prorating the applicable mass standards (kilograms of total HAP per megagram of ODP) for bleached and unbleached... 40 Protection of Environment 10 2014-07-01 2014-07-01 false Standards for kraft pulping process...

The Hunt for Pristine Cretaceous Astronomical Rhythms at Demerara Rise (Cenomanian-Coniacian)

NASA Astrophysics Data System (ADS)

Ma, C.; Meyers, S. R.

2014-12-01

Rhythmic Upper Cretaceous strata from Demerara Rise (ODP leg 207) preserve a strong astronomical signature, and this attribute has facilitated the development of continuous astrochronologies to refine the geologic time scale and calibrate Late Cretaceous biogeochemical events. While the mere identification of astronomical rhythms is a crucial first step in many deep-time paleoceanographic investigations, accurate evaluation of often subtle amplitude and frequency modulations are required to: (1) robustly constrain the linkage between climate and sedimentation, and (2) evaluate the plausibility of different theoretical astrodynamical models. The availability of a wide range of geophysical, lithologic and geochemical data from multiple sites drilled at Demerara Rise - when coupled with recent innovations in the statistical analysis of cyclostratigraphic data - provides an opportunity to hunt for the most pristine record of Cretaceous astronomical rhythms at a tropical Atlantic location. To do so, a statistical metric is developed to evaluate the "internal" consistency of hypothesized astronomical rhythms observed in each data set, particularly with regard to the expected astronomical amplitude modulations. In this presentation, we focus on how the new analysis yields refinements to the existing astrochronologies, provides constraints on the linkages between climate and sedimentation (including the deposition of organic carbon-rich sediments at Demerara Rise), and allows a quantitative evaluation of the continuity of deposition across sites at multiple temporal scales.

Stability, chromatin association and functional activity of mammalian pre-replication complex proteins during the cell cycle

PubMed Central

Okuno, Yukiko; McNairn, Adrian J.; den Elzen, Nicole; Pines, Jonathon; Gilbert, David M.

2001-01-01

We have examined the behavior of pre-replication complex (pre-RC) proteins in relation to key cell cycle transitions in Chinese Hamster Ovary (CHO) cells. ORC1, ORC4 and Cdc6 were stable (T1/2 >2 h) and associated with a chromatin-containing fraction throughout the cell cycle. Green fluorescent protein-tagged ORC1 associated with chromatin throughout mitosis in living cells and co-localized with ORC4 in metaphase spreads. Association of Mcm proteins with chromatin took place during telophase, ∼30 min after the destruction of geminin and cyclins A and B, and was coincident with the licensing of chromatin to replicate in geminin-supplemented Xenopus egg extracts. Neither Mcm recruitment nor licensing required protein synthesis throughout mitosis. Moreover, licensing could be uncoupled from origin specification in geminin-supplemented extracts; site-specific initiation within the dihydrofolate reductase locus required nuclei from cells that had passed through the origin decision point (ODP). These results demonstrate that mammalian pre-RC assembly takes place during telophase, mediated by post-translational modifications of pre-existing proteins, and is not sufficient to select specific origin sites. A subsequent, as yet undefined, step selects which pre-RCs will function as replication origins. PMID:11483529

Gas content and composition of gas hydrate from sediments of the southeastern North American continental margin

USGS Publications Warehouse

Lorenson, T.D.; Collett, T.S.

2000-01-01

Gas hydrate samples were recovered from four sites (Sites 994, 995, 996, and 997) along the crest of the Blake Ridge during Ocean Drilling Program (ODP) Leg 164. At Site 996, an area of active gas venting, pockmarks, and chemosynthetic communities, vein-like gas hydrate was recovered from less than 1 meter below seafloor (mbsf) and intermittently through the maximum cored depth of 63 mbsf. In contrast, massive gas hydrate, probably fault filling and/or stratigraphically controlled, was recovered from depths of 260 mbsf at Site 994, and from 331 mbsf at Site 997. Downhole-logging data, along with geochemical and core temperature profiles, indicate that gas hydrate at Sites 994, 995, and 997 occurs from about 180 to 450 mbsf and is dispersed in sediment as 5- to 30-m-thick zones of up to about 15% bulk volume gas hydrate. Selected gas hydrate samples were placed in a sealed chamber and allowed to dissociate. Evolved gas to water volumetric ratios measured on seven samples from Site 996 ranged from 20 to 143 mL gas/mL water to 154 mL gas/mL water in one sample from Site 994, and to 139 mL gas/mL water in one sample from Site 997, which can be compared to the theoretical maximum gas to water ratio of 216. These ratios are minimum gas/water ratios for gas hydrate because of partial dissociation during core recovery and potential contamination with pore waters. Nonetheless, the maximum measured volumetric ratio indicates that at least 71% of the cages in this gas hydrate were filled with gas molecules. When corrections for pore-water contamination are made, these volumetric ratios range from 29 to 204, suggesting that cages in some natural gas hydrate are nearly filled. Methane comprises the bulk of the evolved gas from all sites (98.4%-99.9% methane and 0%-1.5% CO2). Site 996 hydrate contained little CO2 (0%-0.56%). Ethane concentrations differed significantly from Site 996, where they ranged from 720 to 1010 parts per million by volume (ppmv), to Sites 994 and 997, which contained much less ethane (up to 86 ppmv). Up to 19 ppmv propane and other higher homologues were noted; however, these gases are likely contaminants derived from sediment in some hydrate samples. CO2 concentrations are less in gas hydrate than in the surrounding sediment, likely an artifact of core depressurization, which released CO2 derived from dissolved organic carbon (DIC) into sediment. The isotopic composition of methane from gas hydrate ranges from ??13C of -62.5??? to -70.7??? and ??D of -175??? to -200??? and is identical to the isotopic composition of methane from surrounding sediment. Methane of this isotopic composition is mainly microbial in origin and likely produced by bacterial reduction of bicarbonate. The hydrocarbon gases here are likely the products of early microbial diagenesis. The isotopic composition of CO2 from gas hydrate ranges from ??13C of -5.7 to -6.9, about 15??? lighter than CO2 derived from nearby sediment.

Holocene Planktonic Foraminiferal Assemblage Shifts on the California Margin; Environmental Forcing of Medieval Chumash Society?

NASA Astrophysics Data System (ADS)

Fisler, J. A.; Hendy, I.

2005-12-01

The contribution of D. Kennett and J.P. Kennett to recent literature on native Chumash cultural evolution has linked societal changes between 500 and 1300 A.D. with a rapidly-changing environment. As large-amplitude fluctuations in surface water and climate conditions at the California Margin would have had severe implications for local flora and fauna, high resolution paleooceanographic records from ODP Site 893 should record these environmental changes. The planktonic foraminifera of Santa Barbara Basin are known to be sensitive to climate change over glacial/interglacial and stadial/interstadial time scales. Here we present a Holocene record of planktonic foraminiferal assemblage change that demonstrates this sensitivity continued through what is generally considered to be a warm stable climatic interval. Absolute numbers of planktonic foraminifera specimens decreased through the Holocene, from a peak of over 30,000 specimens/cm3 at 9 kyr BP to several thousand in the last millennia. Eurythermal, high nutrient species G. bulloides and G. quinqueloba show opposite abundance trends throughout deglaciation, with significant decreases in G. bulloides abundance during the Late Holocene while G. quinqueloba increases in abundance. Significant assemblage shifts occurring at 2 kyr BP are particularly pronounced in N. pachyderma dextral/sinistral ratios. Large fluctuations in the dextral/sinistral ratio occur during this interval, varying between 50 and 95%. The most recent decrease in the ratio occurs 800 yrs BP before returning to modern values at 500 yr BP. Assemblage data suggest more dramatic environmental change than indicated by planktonic oxygen isotope records. While N. pachyderma dextral/sinistral ratios generally follow oxygen isotopes throughout the Holocene, the records decouple at 2 kyr BP when the first substantial decrease in the ratio occurs. Salinity may, in part, explain this observation. ODP Site 893 is located at the confluence of the cool, relatively fresh California Current and the warm, saline Davidson Current. As sinistral N. pachyderma are not found in the modern Santa Barbara Basin assemblage, dextral/sinistral ratio decreases of up to 50% suggests that sea surface temperatures were much cooler during the intervals 1800 to 1300 and 800 to 200 years ago. We suggest during these intervals the California Current dominated surface water masses in the basin. These results are consistent with work of Kennett and colleagues, who proposed that rapid cultural evolution of the native Chumash during the medieval period (500-1300 A.D.) was a response to an anomalously cool, dry, and variable climate.

Detailed structure and tectonics of the Ninetyeast Ridge near Site ODP 758 (on new geophysical data from KNOX06RR cruise of R/V Roger Revelle)

NASA Astrophysics Data System (ADS)

Levchenko, O.; Eisin, A. E.; Ivanenko, A. N.; Marinova, J. G.; Paul, C. F.; Sborshchikov, I. M.; Sager, W. W.

2008-12-01

Detailed geophysical survey was carried out during the NSF-funded KNOX06RR cruise of R/V Roger Revelle in July 2007 over the ~70×70 km area near ODP Site 758, the northern Ninetyeast Ridge (NER). In addition to multibeam echo-sounder bathymetry, 3.5 kHz echo-sounder profiles, magnetic, and gravity data, high-resolution multichannel seismic reflection data were collected on eight orthogonal profiles of total length ~270 km. Large NE-trending depressions with complicated horst and graben morphology dominate the whole detailed survey area. The numerous basement faults extend upward into overlying sediments filling out these depressions. Thickness of the sedimentary fill is highly variable due to very rough basement topography, and is up to 800 m maximum. This fill is divided in two clear sedimentary layers: transparent pelagic sediments above and stratified shallow-water ones below. Two high ~400-450 m isometric seamounts extend from the surrounding NER seafloor. High-resolution seismic records show that these igneous basement highs are covered by thin transparent pelagic sediments which hamper the dredging of volcanic rocks. Seismic stratigraphy analyses for sedimentary cover over the seamounts buried slopes suggest that they seem to be recent volcanoes superimposed on the main NER edifice. Both volcanoes are clearly delineated in the constructed map of total anomaly magnetic field. Since water depths are ~2.5 km above these seamounts, the lower edge of the magnetic body in these volcanoes is situated deep at ~7 km under sea level. That appears to represent deep roots of the volcanoes. Preliminary magnetic modeling shows that they were generated during negative chron of the geomagnetic scale rather not long ago and not far from their present location, seeming to confirm the inference that these volcanoes are recent in origin. In general, one may assume a secondary phase of magmatic activity on the NER. It is important to reveal, any recent phase of tectonic and magnetic activity occurred over the northern NER during the same time of well-known intense intraplate deformation in the Central Indian Basin which was initiated ~8 Ma in response to growing regional compression due to continental collision Hindustan and Eurasia. It appears to be nonrandom that this NER segment is located in an anomalous zone of high oceanic intraplate seismicity. Seismic stratigraphy analyses of high-resolution seismic records over the fault features simultaneously with careful study of reflectors on the buried slopes of the recent volcanoes will allow us to examine this problem.

Estimates of Eastern Equatorial Pacific Sea Surface Temperatures During the Pliocene From Carbonate 'Clumped Isotope' Thermometry

NASA Astrophysics Data System (ADS)

Thiagarajan, N.; Tripati, A.; Eiler, J.

2007-12-01

The early Pliocene (5 to 3 Ma) was an interval in Earth history that was globally warmer than the present; thus, study of the details of Pliocene climate can provide insights into the dynamics of warm climates. There are two competing models of the temperature structure of the tropical Pacific upper-ocean during the early Pliocene: the dynamical 'ocean thermostat' model [1,2] and the 'El Padre' (or permanent 'El Nino') model [3], each of which predict zonal temperature gradients and mean conditions in the Eastern Equatorial Pacific (EEP), and which differ markedly from one another in these predictions. The dynamical 'ocean thermostat' model predicts an increased temperature contrast between the Western Equatorial Pacific (WEP) and EEP, enhanced thermocline tilt and intensified upwelling under warmer conditions. In contrast, the 'El Padre' model postulates a collapse of the zonal temperature gradient, reduced thermocline tilt and a reduction in upwelling and/or warmer temperatures of upwelled waters. Existing reconstructions of tropical temperatures produce WEP sea surface temperatures which agree with each other, but yield very different results in the EEP [4,5]. We have reconstructed EEP sea surface temperatures at Ocean Drilling Program (ODP) Site 847 using a few samples spanning key intervals of the last 6 million years using carbonate clumped isotope thermometer [6,7,8]. This technique is based on the temperature dependence of the abundances of 13C-18O bonds in carbonate minerals. Initial measurements of planktonic foraminifera and coccoliths from ODP Site 847 indicate cool EEP sea surface temperatures, supporting models of Pliocene climate that have enhanced zonal temperature gradients, relative to modern. Analyses of Globigerinoides sacculifer (with sac) from sediments indicate calcification temperatures of 20.3°C ± 0.1°C and seawater δ18O values of -0.8‰ ± 0.1‰ from ~6.1 to 5.1 million years ago. Measurements of a mixed coccolith assemblage from the fine fraction of 5.6 Ma sediments show calcification temperatures of 20.4°C ± 2.3°C and seawater δ18O values of -1.4‰ ± 0.6‰. G. sacculifer (with sac) and mixed coccoliths from 1.4 Ma sediments yield calcification temperatures of 22.3°C ± 2.5°C and seawater δ18O values of 1.7‰ ± 0.7‰, and 19.4°C ± 1.8°C and seawater δ18O values of 0.4‰ ± 0.5‰, respectively. Our preliminary findings are consistent with the 'dynamical ocean thermostat' model. [1] Clement, A., et al., 1996, An Ocean Dynamical Thermostat, J. of Clim., 9, 2190-2196. [2] Cane, M., et al., 1997, Twentieth-Century Sea Surface Temperature Trends, Science, 957-960. [3] Fedorov, A., et al., 2006, The Pliocene Paradox (Mechanisms for a permanent El Nino), Science, 312, 1437-1443. [4] Rickaby, R. and Halloran, P., 2005, Cool La Nina during the warmth of the Pliocene?, Science, 307, 1948-1953. [5] Wara, M., et al. ,2005, Permanent El Nino-like conditions during the Pliocene Warm Period, Science, 309, 758-761. [6] Ghosh, P., et al., 2006, 13C-18O bonds in carbonate minerals: A new kind of paleothermometer, GCA, 70, 1439-1456. [7] Eiler, J. and Tripati, A., 2007, 'Clumped isotope' thermometry in benthic foraminifera and ostracods: A novel tool for reconstructing deep-ocean temperatures. Fall AGU. [8] Tripati, A., et al. 2007, 'Carbonate `clumped isotope' thermometry in planktonic foraminifera and coccoliths. Fall AGU.

Subsurface dolomite formation during post-depositional flow of sulphate-bearing fluids from underlying salt giants: Early Pliocene example at DSDP Leg 42A, Site 374, Ionian Abyssal Plain

NASA Astrophysics Data System (ADS)

McKenzie, Judith A.; Evans, Nick; Hodell, David; Aloisi, Giovanni; Vasconcelos, Crisogono

2017-04-01

Deciphering exact mechanisms for the formation of massive dolomite deposits has long been an enigma in sedimentary geology. The recognition that microbes can play a role in the dolomite precipitation process has added a new dimension to the study of the origin of dolomite formations in both shallow and deep-water environments. This scientific advance has evolved, particularly, through the investigation of dolomite-containing, organic-rich hemipelagic sediments cored on various continental margins during DSDP and ODP drilling campaigns, as well as intensive evaluations of modern hypersaline dolomite-precipitating environments with complementary culture experiments conducted in the laboratory. For example, the association of an active subsurface microbial community in contact with underlying brines of unknown origin leading to in situ dolomite precipitation has been observed in a Quaternary sequence of hemi-pelagic, organic carbon-rich sediments drilled on the Peru Margin, ODP Leg 201, Site 1229 (1). Specifically, it can be concluded that the long-term activity of subsurface microbes can be maintained by post-depositional flow of sulfate-bearing fluids from underlying large-scale evaporite deposits, or salt giants, promoting in situ dolomite precipitation. Another example of dolomite precipitation directly associated with the underlying Messinian salt giant was found at DSDP Leg 42A, Site 374 in the Ionian Abyssal Plain. Deep-sea drilling recovered a lowermost Pliocene sequence of diagenetically altered sediment (Unit II) separating the overlying Pliocene open-marine deposits (Unit I) and the underlying end Messinian dolomitic mudstone with gypsum layers (Unit III). The lower portion of this altered interval contained in Core 11, Section 2 (378.0 - 381.5 mbsf) comprises a dolomicrite with an unusual crystal morphology (2). The original interstitial water geochemical profiles indicate that a saline brine is diffusing upwards from below and into the dolomicrite sequence. There appears to be on-going bacterial sulfate reduction in this boundary zone between the evaporitic and normal pelagic sediments with a significant decrease in sulfate concentrations, whereas the chloride profile remains constant. It was concluded that the earliest Pliocene marine sediments of Unit II had been dolomitized after burial as a consequence of ionic migration across a steep Mg-concentration gradient (3). However, with the addition of a microbial factor into the study of the dolomite precipitation process, an alternate interpretation is possible. We propose that, at the location of DSDP Leg 42A, Site 374, modern subsurface dolomite precipitation is ongoing and the site is a "natural laboratory" in which to investigate the microbial phenomenon in the context of a giant evaporite deposit. This actualistic example may provide a new model for the origin of massive dolomite deposits associated with other salt giants in the rock record. (1) Meister, P., et al., 2007. Sedimentology, 54, 1007-1031. (2) Bernoulli, D. & Mélières, F., 1978. In: Hsü, K., Montadert, L. et al., 1978. Initial Reports of the Deep Sea Drilling Project, Volume 42, Part 1, 621-633. (3) McDuff, R.E., et al., 1978. In: Hsü, K., Montadert, L. et al., 1978. Initial Reports of the Deep Sea Drilling Project, Volume 42, Part 1, 561-568.

Massive Pyroclastic Eruptions Accompanied the Sector Collapse of Oahu and the Nu`uanu Landslide: Petrological Evidence for a Submarine Directed Blast

NASA Astrophysics Data System (ADS)

Natland, J. H.; Atlas, Z.

2003-12-01

During ODP Leg 200 in December, 2002, a series of thinly bedded volcaniclastic turbidites and silty muds interbedded with two thicker and strongly indurated vitric tuffs was drilled at Site 1223 on the crest of the Hawaiian arch east of the island of Oahu. The massive Nu`uanu landslide debris field, derived from a massive collapse of the eastern half of Oahu at about 2 Ma, lies in the flexural moat between the site and the island. The shipboard interpretation (1) was that the muds and silts are typical turbidites derived by redeposition from beaches and nearshore benches, but that the tuffs represent the distal portions of large submarine pyroclastic eruptions that may have attended the landslide. We report electron probe microanalyses of basaltic glass, olivine, Cr-spinel, palagonite and secondary minerals in the tuffs supporting the shipboard interpretation. In particular, the glass compositions from individual thin sections match precisely the range of compositions obtained from numerous samples of coarse volcaniclastic breccia sampled from the steep flanks of landslide blocks in the moat (2). This includes somewhat higher SiO2 and lower total iron as FeO(T) at given MgO than similar basaltic glasses from other Hawaiian volcanoes, a distinctive attribute of tholeiitic basalt from Oahu's Ko`olau volcano. Key attributes of the glasses in the tuffs and the minerals in them are that they are poly-compositional and they are strongly differentiated, with a range of compositions typical of those erupted from modern Hawaiian volcanic rift systems supplied by lateral diking from central conduits. The finer-grained tuffs at Site 1223 thus are indeed a distal pyroclastic facies that seemingly tapped much of the suddenly exposed, magma-inflated, deep flanking rift system of Ko`olau volcano. Over-steepening of the NE flank of the volcano coupled with internal weakening provided by near saturation of its rift system with magma may have triggered the landslide. This was almost immediately followed by massive submarine pyroclastic eruptions of magma mainly at submarine levels in the rift that, accelerated by steep downslope descent, were directed all the way to the ENE in rapidly-moving debris flows. These sorted themselves by size (mass) with the coarsest material plastering the sides of the landslide blocks, and the finer grained material, mainly glass and olivine grains, reaching the crest of the Hawaiian arch. The palagonite is compositionally-modified glass that probably formed by leaching in response to lateral migration of warm hydrothermal fluids from beneath thicker and still hot proximal pyroclastic material that was abruptly deposited in the moat to the west following the landslide. (1)Shipboard Scientific Party, 2003. Site 1223. In Stephen, R.A., Kasahara, J., Acton, G.D., et al., Proc. ODP, Init. Rept. 200 [CD-ROM], College Station, TX (Ocean Drill. Prog), 1-159. (2)Clague, D.A., Moore, J.G., and Davis, A.S., 2002. In Takahashi, E.,Lipman, P., Garcia, M.O., and Aramaki, S., (Eds.), Geophys. Monog. 128: Washington (AGU), 279-296.

78 FR 43781 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-22

.... The incorporation by reference of certain publications listed in the regulations is approved by the... reference in the amendment is as follows: For Examination-- 1. FAA Rules Docket, FAA Headquarters Building... and ODP copies may be obtained from: 1. FAA Public Inquiry Center (APA-200), FAA Headquarters Building...

78 FR 14009 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-03-04

.... The incorporation by reference of certain publications listed in the regulations is approved by the... reference in the amendment is as follows: For Examination-- 1. FAA Rules Docket, FAA Headquarters Building... and ODP copies may be obtained from: 1. FAA Public Inquiry Center (APA-200), FAA Headquarters Building...

77 FR 51896 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-08-28

... provisions. The incorporation by reference of certain publications listed in the regulations is approved by... incorporated by reference in the amendment is as follows: For Examination-- 1. FAA Rules Docket, FAA..., individual SIAP and Takeoff Minimums and ODP copies may be obtained from: 1. FAA Public Inquiry Center (APA...

77 FR 71494 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-12-03

... provisions. The incorporation by reference of certain publications listed in the regulations is approved by... incorporated by reference in the amendment is as follows: For Examination-- 1. FAA Rules Docket, FAA... Minimums and ODP copies may be obtained from: 1. FAA Public Inquiry Center (APA-200), FAA Headquarters...

The Advanced Security Operations Corporation Special Weapons and Tactics Initiative: A Business Plan

DTIC Science & Technology

2004-12-01

5 Kotler , Philip . (2003). A Framework for Marketing Management (2nd ed.). New Jersey: Pearson Education. 8 teams in Los...www.ojp.usdoj.gov/odp/docs/fy04hsgp_appkit.pdf 5. Kotler , Philip . (2003). A Framework for Marketing Management (2nd ed.). New Jersey: Pearson Education. 6

Kinetic studies of halon replacements.

NASA Astrophysics Data System (ADS)

Orkin, Vladimir L.

2013-04-01

Despite their excellence as fire suppressants, the production of halons (bromofluorocarbons) is being phased out because of the danger they pose to the Earth's stratospheric ozone layer. A number of bromine free substances have been proposed and tested, but the effort to find replacements continues to return to bromine-containing compounds because of the properties of bromine as a chemically active flame suppressant. The primary approach to this problem has been to test candidate replacement compounds that have short atmospheric lifetimes or/and lack bromine, the halogen atoms that catalyze ozone destruction. Various chemical classes (alkanes, ethers, alkenes) have been studied both earlier and recently. The reaction with atmospheric hydroxyl radicals dictates the residence time and accumulation in the atmosphere of all potential halon replacements. Therefore, we improved a flash photolysis - resonance fluorescence apparatus to provide the most accurate OH reaction rate constants measured over the atmospheric temperatures. Supplementary UV absorption spectra were measured to allow the estimation of ODPs. Although a thorough 3-D modeling is required to assess ODPs, the simplified estimations can be made based on the compounds lifetimes.

Life cycle assessment of a printed circuit board manufacturing plant in Turkey.

PubMed

Ozkan, Elif; Elginoz, Nilay; Germirli Babuna, Fatos

2017-09-29

The objective of this study is to investigate the environmental impacts of a printed circuit board (PCB) manufacturing plant through streamlined life cycle assessment approach. As a result, the most effective recommendations on minimizing the environmental impacts for the mentioned sector are revealed and first steps towards establishing a country specific database are taken. The whole PCB production consists of two consecutive stages: namely board fabrication followed by the manufacturing of PCB. Manufacturing of PCB contributes the highest shares to freshwater aquatic ecotoxicity potential (FAETP) and ozone layer depletion potential (ODP). Eighty-nine percent of FAETP is found to be generated from the manufacturing of PCB. Almost all of this contribution can be attributed to the disposal of copper containing wastewater treatment sludge from etching operations to incineration. On the other hand, PCB manufacturing has 73% share in total ODP. Within the manufacturing of PCB, as etching operations are found to be of importance for all the impact categories except eutrophication potential (EP), it is recommended to focus further studies on in-plant control of etching.

Ontology patterns for complex topographic feature yypes

USGS Publications Warehouse

Varanka, Dalia E.

2011-01-01

Complex feature types are defined as integrated relations between basic features for a shared meaning or concept. The shared semantic concept is difficult to define in commonly used geographic information systems (GIS) and remote sensing technologies. The role of spatial relations between complex feature parts was recognized in early GIS literature, but had limited representation in the feature or coverage data models of GIS. Spatial relations are more explicitly specified in semantic technology. In this paper, semantics for topographic feature ontology design patterns (ODP) are developed as data models for the representation of complex features. In the context of topographic processes, component assemblages are supported by resource systems and are found on local landscapes. The topographic ontology is organized across six thematic modules that can account for basic feature types, resource systems, and landscape types. Types of complex feature attributes include location, generative processes and physical description. Node/edge networks model standard spatial relations and relations specific to topographic science to represent complex features. To demonstrate these concepts, data from The National Map of the U. S. Geological Survey was converted and assembled into ODP.

Architecture for Survivable System Processing (ASSP)

NASA Astrophysics Data System (ADS)

Wood, Richard J.

1991-11-01

The Architecture for Survivable System Processing (ASSP) Program is a multi-phase effort to implement Department of Defense (DOD) and commercially developed high-tech hardware, software, and architectures for reliable space avionics and ground based systems. System configuration options provide processing capabilities to address Time Dependent Processing (TDP), Object Dependent Processing (ODP), and Mission Dependent Processing (MDP) requirements through Open System Architecture (OSA) alternatives that allow for the enhancement, incorporation, and capitalization of a broad range of development assets. High technology developments in hardware, software, and networking models, address technology challenges of long processor life times, fault tolerance, reliability, throughput, memories, radiation hardening, size, weight, power (SWAP) and security. Hardware and software design, development, and implementation focus on the interconnectivity/interoperability of an open system architecture and is being developed to apply new technology into practical OSA components. To insure for widely acceptable architecture capable of interfacing with various commercial and military components, this program provides for regular interactions with standardization working groups (e.g.) the International Standards Organization (ISO), American National Standards Institute (ANSI), Society of Automotive Engineers (SAE), and Institute of Electrical and Electronic Engineers (IEEE). Selection of a viable open architecture is based on the widely accepted standards that implement the ISO/OSI Reference Model.

Architecture for Survivable System Processing (ASSP)

NASA Technical Reports Server (NTRS)

Wood, Richard J.

1991-01-01

The Architecture for Survivable System Processing (ASSP) Program is a multi-phase effort to implement Department of Defense (DOD) and commercially developed high-tech hardware, software, and architectures for reliable space avionics and ground based systems. System configuration options provide processing capabilities to address Time Dependent Processing (TDP), Object Dependent Processing (ODP), and Mission Dependent Processing (MDP) requirements through Open System Architecture (OSA) alternatives that allow for the enhancement, incorporation, and capitalization of a broad range of development assets. High technology developments in hardware, software, and networking models, address technology challenges of long processor life times, fault tolerance, reliability, throughput, memories, radiation hardening, size, weight, power (SWAP) and security. Hardware and software design, development, and implementation focus on the interconnectivity/interoperability of an open system architecture and is being developed to apply new technology into practical OSA components. To insure for widely acceptable architecture capable of interfacing with various commercial and military components, this program provides for regular interactions with standardization working groups (e.g.) the International Standards Organization (ISO), American National Standards Institute (ANSI), Society of Automotive Engineers (SAE), and Institute of Electrical and Electronic Engineers (IEEE). Selection of a viable open architecture is based on the widely accepted standards that implement the ISO/OSI Reference Model.

Paleomagnetic evidence from land-based and ODP cores for clockwise rotation and northward translation of the Phillippine Sea plate

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

Cisowski, S.M.; Fuller, M.; Haston, R.B.

1990-06-01

On-land and deep-sea core paleomagnetic data have been collected from around the Philippine Sea plate. Data from the Palau islands suggest 70{degree} of clockwise rotation and northward translation since the mid-Oligocene. The authors interpret this rotation as a rotation of the West Philippine Sea basin as a whole. New paleomagnetic data from Guam indicate 70{degree} of clockwise rotation and northward translation since the early Oligocene. Although Eocene results have been previously quoted, the new data suggest that there is no reliable Eocene data from Guam. New data from Saipan suggest 50-60{degree} of clockwise rotation since the Late Eocene and 20{degree}more » of clockwise rotation since the mid-Miocene, along with northward translation. During ODP Leg 126, a new technique utilizing the formation microscanner logging tool was employed to obtain orientated drill cores from the Bonin forearc basin. Preliminary results indicate that 70-110{degree} of clockwise rotation has occurred there since the mid-Oligocene. Inclination studies on cores from ODP Legs 125 and 126 along with the on-land paleomagnetic data support 15{degree} of northward translation of the Philippine Sea plate since the mid-Oligocene. The consistent clockwise rotations found around the Philippine Sea plate suggest that the entire plate, including the Bonin and Mariana arcs, has rotated more than 50{degree} since the mid-Oligocene. The similarity of Oligocene results from the Bonin forearc and Guam suggest that little or no relative rotation has occurred between these two points. This implies that the shape of the Mariana arc is probably not due to rotational deformation. The northward translation and clockwise rotation of the Philippine Sea plate established oblique subduction along the proto-Philippine margin, which could account for the 600 km of subducted slab beneath the eastern Celebes Sea.« less

Sulphide mineral evolution and metal mobility during alteration of the oceanic crust: Insights from ODP Hole 1256D

NASA Astrophysics Data System (ADS)

Patten, C. G. C.; Pitcairn, I. K.; Teagle, D. A. H.; Harris, M.

2016-11-01

Fluxes of metals during the hydrothermal alteration of the oceanic crust have far reaching effects including buffering of the compositions of the ocean and lithosphere, supporting microbial life and the formation of sulphide ore deposits. The mechanisms responsible for metal mobilisation during the evolution of the oceanic crust are complex and are neither fully constrained nor quantified. Investigations into the mineral reactions that release metals, such as sulphide leaching, would generate better understanding of the controls on metal mobility in the oceanic crust. We investigate the sulphide and oxide mineral paragenesis and the extent to which these minerals control the metal budget in samples from Ocean Drilling Program (ODP) Hole 1256D. The ODP Hole 1256D drill core provides a unique sample suite representative of a complete section of a fast-spreading oceanic crust from the volcanic section down to the plutonic complex. The sulphide population at Hole 1256D is divided into five groups based on mineralogical assemblage, lithological location and texture: the magmatic, metasomatised, high temperature hydrothermal, low temperature and patchy sulphides. The initiation of hydrothermal alteration by downward flow of moderate temperature (250-350 °C) hydrothermal fluids under oxidising conditions leads to metasomatism of the magmatic sulphides in the sheeted dyke and plutonic complexes. Subsequent increase in the degree of hydrothermal alteration at temperatures >350 °C under reducing conditions then leads to the leaching of the metasomatised sulphides by rising hydrothermal fluids. Mass balance calculations show that the mobility of Cu, Se and Au occurs through sulphide leaching during high temperature hydrothermal alteration and that the mobility of Zn, As, Sb and Pb is controlled by silicate rather than sulphide alteration. Sulphide leaching is not complete at Hole 1256D and more advanced alteration would mobilise greater masses of metals. Alteration of oxide minerals does not release significant quantities of metal into the hydrothermal fluid at Hole 1256D. Mixing of rising high temperature fluids with low temperature fluids, either in the upper sheeted dyke section or in the transitional zone, triggers local high temperature hydrothermal sulphide precipitation and trapping of Co, Ni, Cu, Zn, As, Ag, Sb, Se, Te, Au, Hg and Pb. In the volcanic section, low temperature fluid circulation (<150 °C) leads to low temperature sulphide precipitation in the form of pyrite fronts that have high As concentrations due to uptake from the circulating fluids. Deep late low temperature circulation in the sheeted dyke and the plutonic complexes results in local precipitation of patchy sulphides and local metal remobilisation. Control of sulphides over Au, Se and Cu throughout fast-spreading mid-oceanic crust history implies that the generation of hydrothermal fluids enriched in these metals, which can eventually form VMS deposits, is strongly controlled by sulphide leaching.

Sedimentological and Stable Isotope Changes at the Messinian-Pliocene Boundary Along a West to East Mediterranean Transect.

NASA Astrophysics Data System (ADS)

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

2001-12-01

During Messinian times, the whole Mediterranean area was submitted to evaporitic conditions which ended by the "Lago-Mare" brackish episode before the reset of open marine conditions in the early Pliocene. These major paleoceanographic changes resulted from regional tectonic reorganizations and global climate changes at this critical time interval, both acting to modify drastically the physiography and the hydrological budget of the Mediterranean basins. There exist outcropping sections and a few deep-sea ODP cores which contain the complete and continuous sedimentary sequence of the Messinian-Pliocene boundary (MPB), making it possible to follow the paleoenvironmental changes at a high resolution scale. We compare here sedimentological and carbonate stable isotope records on three sections for which a high- resolution sampling was applied to the 2 meters thick interval including the MPB. In the Vera section from South Spain, there is no clear change in the carbonate content of the silty clay succession when crossing the MPB. The oxygen and carbon isotopic compositions of calcite both increase by 1 permil across a 40 cm-thick interval which corresponds to the Messinian-Pliocene transition. At ODP Site 968 from the eastern Levantine basin, there is an important sedimentary change between Messinian brown silty clays containing about 20 percent of carbonate and Pliocene gray nannofossil ooze which carbonate content averages 60 percent. Across this 10 cm-thick transitional interval, the oxygen and carbon isotopic compositions of bulk calcite both increase by 4.5 permil. In the Pissouri section from Cyprus, the uppermost Messinian reddish to brown marls with paleosoils are overlain by white Pliocene marls. The carbonate content increases from 20 percent to reach 60 percent across a 40 cm-thick transitional interval. Within this interval corresponding to the MPB, the oxygen and carbon isotopic compositions increase by 4 permil and 2 permil respectively. These results indicate that the MPB is recorded everywhere from W to E Mediterranean by significant and sharp increases in the oxygen and carbon isotopic compositions, which indicate that the early Pliocene marine flooding of the Mediterranean basins was a very abrupt event.

Major Cation, Carbon System and Trace Element Chemistry in Pore Waters from a Depth Transect of Cores on the Iberian Margin: Implications for Paleoproxies.

NASA Astrophysics Data System (ADS)

Greaves, M.; Elderfield, H.; Hodell, D. A.; Skinner, L. C.; Sevilgen, D.; Grauel, A. L.; de la Fuente, M.; Misra, S.

2014-12-01

A significant body of work exists on the chemistry of pore waters from DSDP and ODP drilling cores (e.g. Gieskes 1975; Sayles 1981) showing large gradients in sea salt cations and anions interpreted in terms of diagenetic reactions such as the formation of Mg-rich clays and dolomite formation (Higgins and Schrag, 2010). Another class of diagenetic reactions involves the breakdown of organic matter and trace element behaviour (Froelich et al., 1979). The translation of chemical gradients into fluxes requires estimates of pore water chemistry across the sea water - sediment surface boundary. Additionally, the use of the chemistry of benthic foraminiferal calcite for seawater paleochemistry requires estimation of the chemistry of pore waters which may differ from that of bottom seawater because of diagenetic reactions. In this work we have collected multi core samples from 10 core sites on cruise RRS James Cook JC089 on the southwest Iberian continental margin. Pore waters were extracted from the core surface and at 1 cm depth intervals down core (typically to ~40 cm depth) using Rhizon samplers and analysed for Alkalinity, DIC, ∂13C and Na, K, Mg, Ca, Li, Mn, Fe, Ba, B, Sr by atomic emission spectrophotometry as well as O2 penetration and pH by microelectrodes. This has allowed us to inspect chemical behavior at the bottom water - sediment interface. Some examples of results are a large gradient in ∂13C of DIC, the similarity of zero O2 penetration followed by an increase in Mn concentration and then decrease to zero, the similarity of Li to Mn and, in contrast to much DSDP/ODP work, Ca2+ and Mg2+both decrease with depth in pore waters near the sediment surface. References: Gieskes J.M. Annu. Rev. Earth Planet. Sci. 3, 433 (1975). Sayles F. L. Geochim. Cosmochim. Acta45, 1061 (1981). Higgins J.A. and D.P. Schrag. Geochim. Cosmochim. Acta.74, 5039 (2010). Froelich, P.N., et al., Geochim. Cosmochim. Acta. 43, 1075 (1979).

Anomalous Late Jurassic motion of the Pacific Plate with implications for true polar wander

NASA Astrophysics Data System (ADS)

Fu, Roger R.; Kent, Dennis V.

2018-05-01

True polar wander, or TPW, is the rotation of the entire mantle-crust system about an equatorial axis that results in a coherent velocity contribution for all lithospheric plates. One of the most recent candidate TPW events consists of a ∼30° rotation during Late Jurassic time (160-145 Ma). However, existing paleomagnetic documentation of this event derives exclusively from continents, which compose less than 50% of the Earth's surface area and may not reflect motion of the entire mantle-crust system. Additional paleopositional information from the Pacific Basin would significantly enhance coverage of the Earth's surface and allow more rigorous testing for the occurrence of TPW. We perform paleomagnetic analyses on core samples from Ocean Drilling Program (ODP) Site 801B, which were taken from the oldest available Pacific crust, to determine its paleolatitude during the Late Jurassic and Early Cretaceous (167-133 Ma). We find that the Pacific Plate underwent a steady southward drift of 0.49°-0.74° My-1 except for an interval between Kimmeridgian and Tithonian time (157-147 Ma), during which it underwent northward motion at 1.45° ± 0.76° My-1 (1σ). This trajectory indicates that the plates of the Pacific Basin participated in the same large-amplitude (∼30°) rotation as continental lithosphere in the 160-145 Ma interval. Such coherent motion of a large majority of the Earth's surface strongly supports the occurrence of TPW, suggesting that a combination of subducting slabs and rising mantle plumes was sufficient to significantly perturb the Earth's inertia tensor in the Late Jurassic.

Energetic Constraints of Subseafloor Life

NASA Astrophysics Data System (ADS)

D'Hondt, S.; Spivack, A. J.; Wang, G.

2014-12-01

Mean per-cell rates of catabolic activity, energy flux, and biomass turnover are orders of magnitude slower in subseafloor sediment than in the surface world. Despite extreme scarcity of electron donors, competing metabolic pathways co-occur for hundreds of meters deep in subseafloor sediment deposited over millions of years. Our study of an example site (ODP Site 1226) indicates that the energy yields of these competing reactions are pinned to a thermodynamic minimum (Wang et al., 2010). The simplest explanation of this long-term co-existence is thermodynamic cooperation, where microorganisms utilize different but co-existing pathways that remove each other's reaction products. Our Site 1226 results indicate that the energy flux to subseafloor sedimentary microbes is extremely low. Comparison to biomass turnover rates at other sites suggests that most of this flux may be used for building biomolecules from existing components (e.g., amino acids in the surrounding sediment), rather than for de novo biosynthesis from inorganic chemicals. Given these discoveries, ocean drilling provides a tremendous opportunity to address several mysteries of microbial survival and natural selection under extreme energy limitation. Some of these mysteries are centered on microbial communities. To what extent do counted cells in subseafloor sediment constitute a deep microbial necrosphere? How do different kinds of microbes interact to sustain their mean activity at low average rates for millions of years? Other mysteries relate to individual cells. How slowly can a cell metabolize? How long can a cell survive at such low rates of activity? What properties allow microbes to be sustained by low fluxes of energy? In what ways do subseafloor organisms balance the benefit(s) of maximizing energy recovery with the need to minimize biochemical cost(s) of energy recovery? References Wang, G., et al., 2010. Geochimica et Cosmochimica Acta 74, 3938-3947.

Early to middle Miocene climate evolution: benthic oxygen and carbon isotope records from Walvis Ridge Site 1264.

NASA Astrophysics Data System (ADS)

Lourens, L. J.; Beddow, H.; Liebrand, D.; Schrader, C.; Hilgen, F. J.

2016-12-01

Across the early to middle Miocene, high-resolution records from the Pacific Ocean indicate a dynamic climate system, encompassing a 2 Myr global warming event from 17 Ma to 14.7 Ma, followed by a major Cenozoic cooling step at 14.2 Ma -13.8 Ma. Currently, no high-resolution benthic record from the Atlantic Ocean exists covering both events, limiting global coverage of this intriguing period in Cenozoic climate evolution. Here, we present the first early to middle Miocene high-resolution from the Atlantic basin. These records, from Site 1264 on the Walvis Ridge, span a 5.5 Myr long interval (13.24-18.90 ma) in high temporal resolution ( 4 kyr) and are tuned to eccentricity. The d18O record shows a sudden (high-latitude) warming/deglaciation on Antarctica at 17.1 Ma, a rapid cooling/glaciation of Antarctica at 13.8 Ma, and high-amplitude ( 1‰) variability on astronomical time-scales throughout this interval. Together with other records from this time interval located in the Pacific, which show similar features, the data strongly suggests a highly dynamic global climate system. We find cooling steps in d18O at 14.7, 14.2 and 13.8 Ma, suggesting concurrent cooling in the Pacific and Atlantic deep waters during the MMCT. The benthic foraminiferal stable isotope records reveal that the dominant astronomical frequencies present at ODP Site 1264 during the early to middle Miocene interval are the 405 kyr and 110 kyr eccentricity periodicities. This is a contrast to other early to middle Miocene records from drill-sites in the Pacific and South China Sea, which show a strong expression of obliquity in particular between 14.2 and 14.7 Ma.

78 FR 21959 - Extension of Public Comment Period for Request for Information on the FY 2013-2018 Strategic Plan...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-04-12

... Period for Request for Information on the FY 2013-2018 Strategic Plan for the Office of Disease Prevention SUMMARY: The Office of Disease Prevention (ODP), National Institutes of Health (NIH), is amending..., Office of Disease Prevention, National Institutes of Health; phone, 301-496-1508; email, [email protected

75 FR 45047 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-08-02

...;Prices of new books are listed in the first FEDERAL REGISTER issue of each #0;week. #0; #0; #0; #0;#0..., individual SIAP and Takeoff Minimums and ODP copies may be obtained from: 1. FAA Public Inquiry Center (APA... for a special format make publication in the Federal Register expensive and impractical. Furthermore...

The Effect of Bracket Base Pylon Orientation on the Shear Bond Strength of the ODP ANCHOR-LOCK Bracket Pad

DTIC Science & Technology

2013-06-06

El Banna MS, Elsaka SE. Twelve-month bracket failure rate with amorphous calcium phosphate bonding system. Eur J Orthod 2012; doi:10.1093/ejo...material, Cambridge University Press. 1993;3. Willems G, Carels CEL, Verbeke G. In vitro peel /shear bond strength evaluation of orthodontic bracket

75 FR 19541 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-15

.... The large number of SIAPs, Takeoff Minimums and ODPs, in addition to their complex nature and the need... DP, Amdt 2 Alexandria, MN, Chandler Field, RNAV (GPS) RWY 22, Orig Bemidji, MN, Bemidji Rgnl, RNAV (GPS) RWY 25, Orig Granite Falls, MN, Granite Falls Muni/Lenzen-Roe Meml Fld, Takeoff Minimums and...

77 FR 9169 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-16

... on 8260-15A. The large number of SIAPs, Takeoff Minimums and ODPs, in addition to their complex... (GPS) Y RWY 20, Amdt 1B Cambridge, MN, Cambridge Muni, Takeoff Minimums and Obstacle DP, Orig Pipestone, MN, Pipestone Muni, NDB RWY 36, Amdt 7, CANCELLED Rushford, MN, Rushford Muni, Takeoff Minimums and...

78 FR 34559 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-06-10

... airports. These regulatory actions are needed because of the adoption of new or revised criteria, or... Minimums and ODPS contained in this amendment are based on the criteria contained in the U.S. Standard for... criteria were applied to the conditions existing or anticipated at the affected airports. Because of the...

77 FR 31180 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-05-25

... airports. These regulatory actions are needed because of the adoption of new or revised criteria, or... Minimums and ODPS contained in this amendment are based on the criteria contained in the U.S. Standard for... criteria were applied to the conditions existing or anticipated at the affected airports. Because of the...

40 CFR Appendix M to Subpart G of... - Unacceptable Substitutes Listed in the September 30, 2004 Final Rule, Effective November 29, 2004

Code of Federal Regulations, 2014 CFR

2014-07-01

... refrigeration, and sandwich panels —Rigid polyurethane slabstock and other foams —Polystyrene extruded... 29, 2004 Foam Blowing—Unacceptable Substitutes End-use Substitute Decision Comments All foam end-uses: HCFC-141b Unacceptable Alternatives exist with lower or zero = ODP. —Rigid polyurethane and...

40 CFR Appendix M to Subpart G of... - Unacceptable Substitutes Listed in the September 30, 2004 Final Rule, Effective November 29, 2004

Code of Federal Regulations, 2013 CFR

2013-07-01

... refrigeration, and sandwich panels —Rigid polyurethane slabstock and other foams —Polystyrene extruded... 29, 2004 Foam Blowing—Unacceptable Substitutes End-use Substitute Decision Comments All foam end-uses: HCFC-141b Unacceptable Alternatives exist with lower or zero = ODP. —Rigid polyurethane and...

Insights From Magnesium Isotopic Compositions on the Oceanic Hydrothermal Circulation: Is Seamount Weathering the Solution?

NASA Astrophysics Data System (ADS)

Galy, A.; Carder, E.; Elderfield, H.

2006-12-01

It has been long recognised that the input of Mg in the ocean by river is removed by precipitation of Mg-rich bearing phases, either directly from the ocean such as dolomite or through hydrothermal circulation in the oceanic crust. The sampling of hydrothermal fluids demonstrated the efficiency of Mg consumption by the alteration of the oceanic crust, even at temperatures as low as 15°. For high-temperature fluids vented through black or white smokers in the vicinity of the ridge, the Mg concentration is up to 50 time lower than in seawater, and the close relationship between chlorine and Mg led to the idea that seawater was feeding the hydrothermal system and that Mg is quantitatively removed from it during high-T° alteration, the so called zero Mg hypothesis. Despite some hint for a non zero Mg hydrothermal end-member for a handful sites, the low concentration of Mg in oceanic hydrothermal fluids (around 1 mmol/l) has been mainly attributed to contamination by seawater during the sampling. Here we present Mg isotopic composition of 14 seawater samples from the Atlantic, Pacific and Indian Oceans and the Mediterranean and Red Seas and covering a range of depth of almost 5km and 26 hydrothermal fluids from 7 sites in the Atlantic and Pacific Oceans with temperature from 15° to 380°C. We find the magnesium isotope composition of seawater to be constant, with a δ^{26}Mg = -0.82±0.10 ‰ relative to the DSM3 standard. This value is consistent with a long residence time for Mg in seawater. In addition, out of the 26 hydrothermal fluids studied, more than 58% differ from seawater for their Mg isotopic composition by more than 2σ. This number rises up to 88% at 2σmean level and the shift is systematic with the fluids being either indistinguishable from seawater or enriched in light isotopes by up to 2.4‰ in δ^{26}Mg. This clearly demonstrates that fluids having low Mg concentrations are not solely bearing Mg added by contamination during sampling. The isotopic and concentration data are consistent with the preferential incorporation of heavy isotopes of Mg during the weathering and already similar to the mechanisms found in soil (Tipper et al., 2006a, doi:10.1016/j.epsl.2006.04.033). The fractionation factor (α) is around 1.001 for the high-T° fluids, while the low temperature fluids, samples off axis during the ODP Leg 168 (Est of Juan de Fuca Ridge), requires a more variable and higher α of 1.001 to 1.003. At low temperature, the α is somehow greater that the estimate made from the soil formation but the T-α relationship is consistent with the expected behaviour for an equilibrium isotopic fractionation. However, such a large α implies that the significant flux of the low-T component of the hydrothermal circulation required to fulfil the heat budget of the oceanic lithosphere would buffer any isotopic mass balance calculation of the oceanic Mg to an unsustainable value (e.g. Tipper et al., 2006b, doi:10.1016/j.epsl.2006.07.037). Therefore, either the low-T hydrothermal circulation leaves the Mg unaffected, or the off axis fluids from the ODP Leg 168 are not representative of the global low-T hydrothermal circulation. Given that Mg gets significantly re-incorporated in soil processes, we favour the later hypothesis and propose that a significant part of the low-T hydrothermal circulation is occurring around relief of the oceanic floor, including seamounts, with a different residence-time and chemistry than what have been described in the ODP Leg 168 setting.

Evidence of Extensive Gas Venting at the Blake Ridge and Cape Fear Diapirs

NASA Astrophysics Data System (ADS)

Brothers, L.; Van Dover, C. L.; German, C. R.; Yoerger, D. R.; Kaiser, C. L.; Lobecker, M.; Skarke, A. D.; Ruppel, C. D.

2012-12-01

Despite the important geologic, geotechnical and biogeochemical implications of seabed fluid escape, the abundance and global distribution of cold seeps remain poorly characterized. Globally, seabed fluid escape is sometimes associated with chemosynthetic communities. Fluid escape on continental margins has also been invoked as a possible trigger for submarine slope failures and seafloor collapse. Along the U.S. Atlantic Margin, acoustic and geochemical water column anomalies have been observed in the Hudson Canyon, the mid-Atlantic shelf break, and the Blake Ridge Diapir (ODP Leg 164 site 996). Of these areas, only the Blake Ridge Diapir site is known to host chemosynthetic communities, a strong seafloor indicator of active seabed fluid flow. In July 2012, NOAA Ocean Exploration Program expedition EX1205L1 identified and characterized cold seeps within the Blake Ridge gas hydrate province, using the platform Okeanos Explorer and the Autonomous Underwater Vehicle (AUV) Sentry. The expedition observed seven spatially distinct water column anomalies using shipboard EM302 30 kHz multibeam and EK60 18 kHz single beam echosounders. These anomalies originate at the seabed and extend up to 900 m above the seafloor. Interpreted as bubble plumes, these anomalies correspond in six locations to Sentry-collected photos documenting chemosynthetic organisms (e.g. mussels and clams). Three plumes are associated with the known Blake Ridge Diapir seep site, while two additional plumes and newly discovered seep communities occur within 2 km of the original site. For the first time, a gas plume and associated seep community were also observed on the main Cape Fear Diapir. Co-located 3.5 kHz subbottom data, including lines that re-occupy a 3D survey conducted in 2003 across the Blake Ridge Diapir (doi:10.1029/2006GL028859), reveal subsurface conduits presently associated with these seeps and should allow us to constrain the plumbing systems in two and three dimensions. No methane seeps were found along 210 km of surveys conducted at the presumed upper edge of gas hydrate stability on the continental slope between Blake Ridge and the head of the Cape Fear slide. Nonetheless, the discovery of new seeps indicates abundant active methane escape along the southern portion of the US Atlantic Margin and calls for a reevaluation of the role of methane venting in regional seafloor processes there. In addition, these results triple the number of known cold seep communities along the US Atlantic margin, thus providing insight into biogeographic connectivity.

Dispersed Volcanic Ash in Sediment Entering NW Pacific Ocean Subduction Zones: Towards a Regional Perspective

NASA Astrophysics Data System (ADS)

Scudder, R. P.; Murray, R. W.; Underwood, M.; Kutterolf, S.; Plank, T.; Dyonisius, M.; Arshad, M. A.

2011-12-01

Volcanic ash has long been recognized to be an important component of the global sedimentary system. Ash figures prominently in a number of sedimentary and petrophysical investigations, including how the fluid budget of subducting sediment will be affected by hydration/dehydration reactions. Additionally, many studies focus on discrete ash layers, and how to link their presence with volcanism, climate, arc evolution, biological productivity, and other processes. Less widely recognized is the ash that is mixed into the bulk sediment, or "dispersed" ash. Dispersed ash is quantitatively significant and is an under-utilized source of critical geochemical and tectonic information. Based on geochemical studies of ODP Site 1149, a composite of DSDP Sites 579 & 581, as well as IODP Sites C0011 & C0012 drilled during Expedition 322, we will show the importance of dispersed ash to the Izu-Bonin-Marianas, Kurile-Kamchatka and Nankai subduction zones. Initial geochemical analyses of the bulk sediment, as related to dispersed ash entering these subduction systems are presented here. Geochemical analysis shows that the characteristics of the three sites exhibit some variability consistent with observed lithological variations. For example, the average SiO2/Al2O3 ratios at Site 1149, Site C0011 and Site C0012 average 3.7. The composite of Sites 579 & 581 exhibits a higher average of 4.6. There are contrasts between other key major elemental indicators as well (e.g., Fe2O3). Ternary diagrams such as K2O-Na2O-CaO show that there are at least two distinct geochemical fields with Sites 1149, C0011 and C0012 clustering in one and Sites 579 & 581 in the other. Q-mode Factor Analysis was performed on the bulk sediment chemical data in order to determine the composition of potential end members of these sites. The multivariate statistics indicate that Site 1149 has 3-4 end members, consistent with the results of Scudder et al. (2009, EPSL, v. 284, pp 639), while each of the other sites has 4-5 end members. These geochemical signatures (e.g., K2O) of the dispersed ash can be exploited to provide insight into the importance of clay mineralogy (i.e., smectite). Additional results from trace and REE analyses, combined with additional statistical treatments, will also be presented.

Determination of the Mg/Mn ratio in foraminiferal coatings: An approach to correct Mg/Ca temperatures for Mn-rich contaminant phases

NASA Astrophysics Data System (ADS)

Hasenfratz, Adam P.; Martínez-García, Alfredo; Jaccard, Samuel L.; Vance, Derek; Wälle, Markus; Greaves, Mervyn; Haug, Gerald H.

2017-01-01

The occurrence of manganese-rich coatings on foraminifera can have a significant effect on their bulk Mg/Ca ratios thereby biasing seawater temperature reconstructions. The removal of this Mn phase requires a reductive cleaning step, but this has been suggested to preferentially dissolve Mg-rich biogenic carbonate, potentially introducing an analytical bias in paleotemperature estimates. In this study, the geochemical composition of foraminifera tests from Mn-rich sediments from the Antarctic Southern Ocean (ODP Site 1094) was investigated using solution-based and laser ablation ICP-MS in order to determine the amount of Mg incorporated into the coatings. The analysis of planktonic and benthic foraminifera revealed a nearly constant Mg/Mn ratio in the Mn coating of ∼0.2 mol/mol. Consequently, the coating Mg/Mn ratio can be used to correct for the Mg incorporated into the Mn phase by using the down core Mn/Ca values of samples that have not been reductively cleaned. The consistency of the coating Mg/Mn ratio obtained in this study, as well as that found in samples from the Panama Basin, suggests that spatial variation of Mg/Mn in foraminiferal Mn overgrowths may be smaller than expected from Mn nodules and Mn-Ca carbonates. However, a site-specific assessment of the Mg/Mn ratio in foraminiferal coatings is recommended to improve the accuracy of the correction.

Non-synchronous climate change along the western margin of North America during glacial terminations

NASA Astrophysics Data System (ADS)

Herbert, T. D.; Liu, Z.; Barron, J.; Heusser, L.; Lyle, M.; Mix, A.; Ravelo, A. C.

2003-04-01

A regional set of cores now exists to study the evolution of ocean surface temperatures and other paleoclimatic signals along the west coast of North America. Core locations range from Vancouver Island to the north, to the tip of Baja California to the south. We report on the evolution of sea surface temperatures and marine productivity, as recorded by alkenones. Several sites also have pollen records, allowing us to compare marine and terrestrial responses. We find that surface climate signals covary tightly with global climate, as represented by benthic d18O, through 80% of a typical glacial-interglacial cycle. However, the associations during glacial maxima and terminations break into three regional patterns. North of Point Conception (heart of the California Current), SST patterns are very similar to benthic d18O and to Greenland ice core surface temperature data to at least 30 ka (ODP Site 1019). In the California borderland region, warmings begin during peak glacial conditions, and significantly precede the deglacial sea level rise. Off Baja California, SST follows benthic d18O, but without the high frequency oscillations of temperature observed in Greenland. These changes outline regional reorganizations of surface winds and currents during times of maximum ice volume. Our data suggests that the geographic extent and intensity of the California Current system was much reduced during glacial maxima in comparison to modern conditions.

Thorium-derived dust fluxes to the tropical Pacific Ocean, 58 Ma

NASA Astrophysics Data System (ADS)

Woodard, Stella C.; Thomas, Deborah J.; Marcantonio, Franco

2012-06-01

Eolian dust in pelagic deep sea sediments can be used to reconstruct ancient wind patterns and paleoenvironmental response to climate change. Traditional methods to determine dust accumulation involve isolating the non-dissolvable aluminosilicate minerals from deep sea sediments through a series of chemical leaches, but cannot differentiate between minerals from eolian, authigenic and volcanogenic sources. Other geochemical proxies, such as sedimentary 232Th and crustal 4He content, have been used to construct high-resolution records of atmospheric dust fluxes to the deep sea during the Quaternary. Here we use sedimentary Th content as a proxy for terrigenous material (eolian dust) in ˜58 Myr-old sediments from the Shatsky Rise (ODP Site 1209) and compare our results with previous dust estimates generated using the traditional chemical extraction method and sedimentary 4Hecrustal concentrations. We find excellent agreement between Th-based dust estimates and those generated using the traditional method. In addition our results show a correlation between sedimentary Th and 4Hecrustal content, which suggests a source older than present day Asian loess supplied dust to the central subtropical Pacific Ocean during the early Paleogene.

A New ɛNd Record Covering Termination II

NASA Astrophysics Data System (ADS)

Deaney, E. L.; Thornalley, D. J.; van de Flierdt, T.; Kreissig, K.; Barker, S.

2014-12-01

The 143Nd/144Nd ratio (ɛNd) of seawater is used as a quasi-conservative tracer to examine past changes in water mass composition of the deep ocean. Records of ɛNd across the last deglaciation (Termination 1, T1) provide valuable information about water mass mixing that has improved our understanding of the ocean dynamics relevant to the process of deglaciation. However, questions remain concerning end-member source characteristics and regional hydrographic processes. Here we present a high resolution record of ɛNd derived from fish debris from ODP site 1063 across Termination 2. The different external and internal forcing (e.g. insolation versus freshwater) applicable to T2 make this a useful comparator for studies focused on T1. Accordingly we find large (up to 4 ɛNd units) fluctuations across T2 that can be related to high latitude climate changes as recorded by ice cores and other high resolution climate archives. We also identify periods of extremely negative values that require new explanations for changing end-member compositions. Our results have important implications for understanding North Atlantic deep water formation processes during critical climate transitions.

Expansion and diversification of high-latitude radiolarian assemblages in the late Eocene linked to a cooling event in the southwest Pacific

NASA Astrophysics Data System (ADS)

Pascher, K. M.; Hollis, C. J.; Bohaty, S. M.; Cortese, G.; McKay, R. M.; Seebeck, H.; Suzuki, N.; Chiba, K.

2015-12-01

The long-term cooling trend from middle to late Eocene was punctuated by several large-scale climate perturbations that culminated in a shift to "icehouse" climates at the Eocene-Oligocene transition. We present radiolarian micro-fossil assemblage and foraminiferal oxygen and carbon stable isotope data from Deep Sea Drilling Project (DSDP) sites 277, 280, 281, and 283 and Ocean Drilling Project (ODP) Site 1172 to identify significant oceanographic changes in the southwest Pacific through this climate transition (~ 40-30 Ma). We find that the Middle Eocene Climatic Optimum at ~ 40 Ma, which is truncated but identified by a negative shift in foraminiferal δ18O values at Site 277, is associated with a small increase in radiolarian taxa with low-latitude affinities (5 % of total fauna). In the early late Eocene at ~ 37 Ma, a positive oxygen isotope shift at Site 277 is correlated with the Priabonian Oxygen Isotope Maximum (PrOM). Radiolarian abundance, diversity, and preservation increase within this cooling event at Site 277 at the same time as diatom abundance. A negative δ18O excursion above the PrOM is correlated with a late Eocene warming event (~ 36.4 Ma). Radiolarian abundance and diversity decline within this event and taxa with low-latitude affinities reappear. Apart from this short-lived warming event, the PrOM and latest Eocene radiolarian assemblages are characterised by abundant high-latitude taxa. High-latitude taxa are also abundant during the late Eocene and early Oligocene (~ 38-30 Ma) at DSDP sites 280, 281, 283 and 1172 and are associated with very high diatom abundance. We therefore infer a northward expansion of high-latitude radiolarian taxa onto the Campbell Plateau in the latest Eocene. In the early Oligocene there is an overall decrease in radiolarian abundance and diversity at Site 277, and diatoms are scarce. These data indicate that, once the Antarctic Circumpolar Current was established in the early Oligocene (~ 30 Ma), a frontal system similar to present day developed, with nutrient-depleted Subantarctic waters bathing the area around DSDP Site 277, resulting in a more restricted siliceous plankton assemblage.

Outreach to Hispanic/Latino Communities With a Spanish-Language Version of the Earthscope Website

NASA Astrophysics Data System (ADS)

López, A. M.; Stein, S.; Delaughter, J.

2005-12-01

Spanish is estimated to be the fourth language in the world based on number of speakers, the second as a vehicle of international communication and the third as an international language of politics, economics and culture. Its importance in the U.S. is illustrated by the fact that the Hispanic/Latino population is becoming the largest minority group because it has the fastest growth rate of all ethnic groups in the U.S. According to the U.S. Census Bureau, in 2004 there were ~41 million people in the U.S. (~14% of the total population) of Hispanic or Latino origin. Although the Spanish-speaking population is growing rapidly, the same cannot be said about the number of Hispanic/Latino high school and college graduates. Studies by the National Center for Education Statistics show that Hispanic/Latino students are as likely to drop out are to complete high school. Similarly, although more Hispanic/Latino students enroll in college and/or universities than a decade ago, few complete degrees. For example, in the geosciences only 3% of bachelor's degrees were granted to people identifying themselves as Hispanic or Latino. Over the last 28 years, only 263 of the 20,000 geoscience Ph.D.s awarded in the U.S. went to Hispanic Americans. Bilingual educational offerings are one technique for addressing this discrepancy. For example, scientists and research programs such as EarthScope, NASA, NOAA, and ODP frequently reach out to students and the general public using the internet. Many well-made and useful websites with scientific themes in the U.S. are available to millions of users worldwide, providing a resource that is limited or non-existent in other countries. Unfortunately, few geoscience education sites are available in languages other than English. To address this need, Earthscope is developing a Spanish version of its website describing its goals, techniques, and educational opportunities. Currently, approximately 90% of the educational content on this site (http://www.earthscope.org/education/index.php) is available in both English and Spanish. As time and resources permit, more of the site will be translated. This effort is already having an effect; in a recent Google search using the term "Ferias Científicas" (Science Fairs), EarthScope's site ranked second. Such Spanish material will hopefully have several applications relevant to Earthscope goals. They should encourage Spanish-speaking students to explore the geosciences, and help Hispanic populations become more knowledgeable about the Earth by providing information about the geologic processes and hazards in their area in a language they truly understand. In addition, such web sites can provide useful resources to people in Latin American countries, many of which have geologic processes that are an important aspect of their lives.

76 FR 70053 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-11-10

... 8260-15A. The large number of SIAPs, Takeoff Minimums and ODPs, in addition to their complex nature and... Three Rivers, MI, Three Rivers Muni Dr. Haines, Takeoff Minimums and Obstacle DP, Orig Brainerd, MN, Brainerd Lakes Rgnl, ILS OR LOC/DME RWY 34, Amdt 1 Park Rapids, MN, Park Rapids Muni-Konshok Field, NDB RWY...

75 FR 32096 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-07

.... The large number of SIAPs, Takeoff Minimums and ODPs, in addition to their complex nature and the need... Rivers, MI, Three Rivers Muni Dr. Haines, NDB RWY 27, Amdt 7A, CANCELLED Brainerd, MN, Brainerd Lakes Rgnl, RNAV (GPS) RWY 5, Amdt 1 Brainerd, MN, Brainerd Lakes Rgnl, RNAV (GPS) RWY 12, Amdt 1 Brainerd...

78 FR 48800 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-08-12

... 8260-15A. The large number of SIAPs, Takeoff Minimums and ODPs, in addition to their complex nature and..., Takeoff Minimums and Obstacle DP, Amdt 2 Perham, MN, Perham Muni, RNAV (GPS) RWY 13, Orig Perham, MN, Perham Muni, RNAV (GPS) RWY 31, Amdt 1 Perham, MN, Perham Muni, Takeoff Minimums and Obstacle DP, Amdt 1...

78 FR 59808 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-09-30

... ODPs, in addition to their complex nature and the need for a special format make publication in the...-Lapeer, RNAV (GPS) RWY 36, Orig Elbow Lake, MN, Elbow Lake Muni--Pride of the Prairie, RNAV (GPS) RWY 14, Orig Elbow Lake, MN, Elbow Lake Muni--Pride of the Prairie, RNAV (GPS) RWY 32, Orig Elbow Lake, MN...

78 FR 18806 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-03-28

... on 8260-15A. The large number of SIAPs, Takeoff Minimums and ODPs, in addition to their complex..., ILS OR LOC/DME RWY 24, Amdt 2B Faribault, MN, Faribault Muni, RNAV (GPS) RWY 12, Amdt1 Faribault, MN, Faribault Muni, RNAV (GPS) RWY 30, Amdt1 Minneapolis, MN, Minneapolis-St Paul Intl/Wold-Chamberlain, Takeoff...

77 FR 71497 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-12-03

.... The large number of SIAPs, Takeoff Minimums and ODPs, in addition to their complex nature and the need.../Springfield, MA, Barnes Muni, RNAV (GPS) RWY 20, Amdt 1 Moose Lake, MN, Moose Lake Carlton County, GPS RWY 4, Orig, CANCELED Moose Lake, MN, Moose Lake Carlton County, RNAV (GPS) RWY 4, Orig Indianola, MS...

76 FR 8291 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-02-14

... 8260-15A. The large number of SIAPs, Takeoff Minimums and ODPs, in addition to their complex nature and... DP, Amdt 3A Ely, MN, Ely Muni, VOR-A, Orig, CANCELLED Paynesville, MN, Paynesville Muni, RNAV (GPS) RWY 11, Orig Paynesville, MN, Paynesville Muni, RNAV (GPS) RWY 29, Orig Kansas City, MO, Kansas City...

Wine tasting based on emotional responses: An expedite approach to distinguish between warm and cool climate dry red wine styles.

PubMed

Coste, Amaury; Sousa, Paulo; Malfeito-Ferreira, Manuel

2018-04-01

In this study, we improved an empirical tasting sheet including emotional responses and common sensory attributes. An Optimized Descriptive Profile (ODP) was run to characterize different red wines according to sensory descriptors used in the improved sheet. A total of 5 wines were evaluated by a Consumer Panel (CP) of 103 subjects (36 females, 67 males) using the improved sheet and a Check-All-That-Apply (CATA) list of 25 emotions. In the ODP, the panel identified the main discriminating sensory attributes as "Complexity", "Astringency" and "Duration of the wine fragrance". However, this analysis did not allow for differentiating very distinct dry red wine styles originating from warmer or cooler regions. On the contrary, Principal Component Analysis of emotional attributes demonstrated that these two wine styles could be easily distinguished. In particular, wine with a red-brick color, complex smell and aggressive mouthfeel consistent with those from cooler regions was less liked by the CP than a warm climate gold-awarded wine. Although receiving lower scores considering its color and smell, the former wine was regarded as the most "surprising" in the CATA. Copyright © 2017 Elsevier Ltd. All rights reserved.

Analysis of trend changes in Northern African palaeo-climate by using Bayesian inference

NASA Astrophysics Data System (ADS)

Schütz, Nadine; Trauth, Martin H.; Holschneider, Matthias

2010-05-01

Climate variability of Northern Africa is of high interest due to climate-evolutionary linkages under study. The reconstruction of the palaeo-climate over long time scales, including the expected linkages (> 3 Ma), is mainly accessible by proxy data from deep sea drilling cores. By concentrating on published data sets, we try to decipher rhythms and trends to detect correlations between different proxy time series by advanced mathematical methods. Our preliminary data is dust concentration, as an indicator for climatic changes such as humidity, from the ODP sites 659, 721 and 967 situated around Northern Africa. Our interest is in challenging the available time series with advanced statistical methods to detect significant trend changes and to compare different model assumptions. For that purpose, we want to avoid the rescaling of the time axis to obtain equidistant time steps for filtering methods. Additionally we demand an plausible description of the errors for the estimated parameters, in terms of confidence intervals. Finally, depending on what model we restrict on, we also want an insight in the parameter structure of the assumed models. To gain this information, we focus on Bayesian inference by formulating the problem as a linear mixed model, so that the expectation and deviation are of linear structure. By using the Bayesian method we can formulate the posteriori density as a function of the model parameters and calculate this probability density in the parameter space. Depending which parameters are of interest, we analytically and numerically marginalize the posteriori with respect to the remaining parameters of less interest. We apply a simple linear mixed model to calculate the posteriori densities of the ODP sites 659 and 721 concerning the last 5 Ma at maximum. From preliminary calculations on these data sets, we can confirm results gained by the method of breakfit regression combined with block bootstrapping ([1]). We obtain a significant change point around (1.63 - 1.82) Ma, which correlates with a global climate transition due to the establishment of the Walker circulation ([2]). Furthermore we detect another significant change point around (2.7 - 3.2) Ma, which correlates with the end of the Pliocene warm period (permanent El Niño-like conditions) and the onset of a colder global climate ([3], [4]). The discussion on the algorithm, the results of calculated confidence intervals, the available information about the applied model in the parameter space and the comparison of multiple change point models will be presented. [1] Trauth, M.H., et al., Quaternary Science Reviews, 28, 2009 [2] Wara, M.W., et al., Science, Vol. 309, 2005 [3] Chiang, J.C.H., Annual Review of Earth and Planetary Sciences, Vol. 37, 2009 [4] deMenocal, P., Earth and Planetary Science Letters, 220, 2004

ODP Leg 210 Drills the Newfoundland Margin in the Newfoundland-Iberia Non-Volcanic Rift

NASA Astrophysics Data System (ADS)

Tucholke, B. E.; Sibuet, J.

2003-12-01

The final leg of the Ocean Drilling Project (Leg 210, July-September 2003) was devoted to studying the history of rifting and post-rift sedimentation in the Newfoundland-Iberia rift. For the first time, drilling was conducted in the Newfoundland Basin along a transect conjugate to previous drill sites on the Iberia margin (Legs 149 and 173) to obtain data on a complete `non-volcanic' rift system. The prime site during this leg (Site 1276) was drilled in the transition zone between known continental crust and known oceanic crust at chrons M3 and younger. Extensive geophysical work and deep-sea drilling have shown that this transition-zone crust on the conjugate Iberia margin is exhumed continental mantle that is strongly serpentinized in its upper part. Transition-zone crust on the Newfoundland side, however, is typically a kilometer or more shallower and has much smoother topography, and seismic refraction data suggest that the crust may be thin (about 4 km) oceanic crust. A major goal of Site 1276 was to investigate these differences by sampling basement and a strong, basinwide reflection (U) overlying basement. Site 1276 was cored from 800 to 1737 m below seafloor with excellent recovery (avg. 85%), bottoming in two alkaline diabase sills >10 m thick that are estimated to be 100-200 meters above basement. The sills have sedimentary contacts that show extensive hydrothermal metamorphism. Associated sediment structural features indicate that the sills were intruded at shallow levels within highly porous sediments. The upper sill likely is at the level of the U reflection, which correlates with lower Albian - uppermost Aptian(?) fine- to coarse-grained gravity-flow deposits. Overlying lower Albian to lower Oligocene sediments record paleoceanographic conditions similar to those on the Iberia margin and in the main North Atlantic basin, including deposition of `black shales'; however, they show an extensive component of gravity-flow deposits throughout.

Paired measurements of K and Mg isotopes and clay authigenesis in marine sediments

NASA Astrophysics Data System (ADS)

Santiago Ramos, D. P.; Dunlea, A. G.; Higgins, J. A.

2016-12-01

Despite its importance as a major sink for seawater K and Mg, estimates of clay authigenesis in marine sediments remain poorly constrained. Previous work on Mg isotope fractionation during clay formation has revealed a preferential uptake of 26Mg, yielding authigenic clay products with potentially distinct δ26Mg compared to the detrital component. In a similar manner, we aim to quantify the K isotope fractionation during authigenic clay formation and to use paired δ26Mg and δ41K measurements as proxies for the identification and quantification of authigenic clays in shallow and deep marine sedimentary systems. To better understand the behavior of paired Mg and K isotopes during authigenic clay formation in marine sediments, we measured δ26Mg and δ41K values of pore-fluids and sediments from ODP/IODP sites 1052, U1395, U1403 and U1366. We find that while pore-fluid K concentrations at sites 1052, U1395 and U1403 all decline with depth, δ41K profiles differ significantly. These differences might be a result of a complex interplay between clay authigenesis, sedimentation rate, and fractionation of K isotopes during diffusion. Results from 1-D diffusion-advection-reaction models suggest that, in contrast to Mg, diffusion may play an important role in determining the overall K isotope fractionation during clay authigenesis in sites with low-sedimentation rates. Sites with high sedimentation rates may act as close systems where diffusion is negligible. In such cases, K uptake can be modeled as a Rayleigh distillation process and K isotope fractionation can be estimated. Measurements of δ26Mg and δ41K of pore-fluids from site U1395 and bulk sediments from U1366 suggest that paired measurements of these isotopic systems in siliciclastic marine sediments can provide new insights into rates of marine clay authigenesis, a globally important but understudied component of many geochemical cycles.

Si-metasomatism in serpentinized peridotite: The effects of talc-alteration on strontium and boron isotopes in abyssal serpentinites from Hole 1268a, ODP Leg 209

NASA Astrophysics Data System (ADS)

Harvey, Jason; Savov, Ivan P.; Agostini, Samuele; Cliff, Robert A.; Walshaw, Richard

2014-02-01

Ultramafic rocks recovered from Hole 1268a, Ocean Drilling Program Leg 209, to the south of the 15°20‧N Fracture Zone on the Mid-Atlantic ridge have experienced a complex history of melt depletion and subsequent interaction with a series of fluids under varying temperature and pH conditions. After intense melt depletion, varying degrees of serpentinization at 100-200 °C took place, initially under seawater-like pH conditions. Subsequently, interaction with a higher temperature (300-350 °C) fluid with low (4-5) pH and low MgO/SiO2 resulted in the heterogeneous alteration of these serpentinites to talc-bearing ultramafic lithologies. The proximity of the currently active, high temperature Logatchev hydrothermal field, located on the opposite flank of the Mid-Atlantic ridge, suggests that unlike more distal localities sampled during ODP Leg 209, Hole 1268a has experienced Si-metasomatism (i.e. talc-alteration) by a Logatchev-like hydrothermal fluid. Serpentinite strontium isotope ratios were not materially shifted by interaction with the subsequent high-T fluid, despite the likelihood that this fluid had locally interacted with mid-ocean ridge gabbro. 87Sr/86Sr in the ultramafic lithologies of Hole 1268a are close to that of seawater (c.0.709) and even acid leached serpentinites retain 87Sr/86Sr in excess of 0.707, indistinguishable from Logatchev hydrothermal fluid. On the other hand, boron isotope ratios appear to have been shifted from seawater-like values in the serpentinites (δ11B = c.+40‰) to much lighter values in talc-altered serpentinites (δ11B = +9 to +20‰). This is likely a consequence of the effects of changing ambient pH and temperature during the mineralogical transition from serpentine to talc. Heterogeneous boron isotope systematics have consequences for the composition of ultramafic portions of the lithosphere returned to the convecting mantle by subduction. Inhomogeneities in δ11B, [B] and mineralogy introduce significant uncertainties in the prediction of the composition of slab fluids released during the early- to mid-stages of subduction.

RECONSTRUCTING PALEO-SMT POSITIONS ON THE CASCADIA MARGIN USING MAGNETIC SUSCEPTIBILITY

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

Johnson, Joel; Phillips, Stephen

2014-09-30

Magnetic susceptibility (κ) is a mixed signal in marine sediments, representing primary depositional and secondary diagenetic processes. Production of hydrogen sulfide via anaerobic oxidation of methane (AOM) at the sulfate-methane transition (SMT) and organoclastic sulfate reduction above the SMT can result in the dissolution of iron oxides, altering κ in sediments in methane gas and gas hydrate bearing regions. We investigated records of κ on the Cascadia margin (ODP Sites 1249 and 1252; IODP Site 1325) using a Zr/Rb heavy mineral proxy from XRF core scanning to identify intervals of primary detrital magnetic susceptibility and intervals and predict intervals affectedmore » by magnetite dissolutions. We also measured total sulfur content, grain size distributions, total organic carbon (TOC) content, and magnetic mineral assemblage. The upper 100 m of Site 1252 contains a short interval of κ driven by primary magnetite, with multiple intervals (> 90 m total) of decreased κ correlated with elevated sulfur content, consistent with dissolution of magnetite and re-precipitation of pyrite. In the upper 90 m of Site 1249, κ is almost entirely altered by diagenetic processes, with much of the low κ explained by a high degree of pyritization, and some intervals affected by the precipitation of magnetic iron sulfides. At Site 1325, κ between 0-20 and 51-73 mbsf represents primary mineralogy, and in the interval 24-51 mbsf, κ may be reduced due to pyritization. This integrated approach allows for a prediction of primary κ and the amount of κ loss at each site when compared to actual κ measurements. In the case of magnetite dissolution and full pyritization, these drawdowns in κ are supported by sulfur measurements, and the exposure times of magnetite to hydrogen sulfide can be modeled. The presence of methane and methane hydrates at these sites, as well as large variations in TOC content, suggest that the past migration rates of the SMT and variation in sulfate reduction rates may influence κ alteration along the Cascadia margin.« less

Reconstruction of the North Atlantic end-member of the Atlantic Meridional Overturning Circulation over glacial-interglacial cycles

NASA Astrophysics Data System (ADS)

Kim, J.; Seguí, M. J.; Knudson, K. P.; Yehudai, M.; Goldstein, S. L.; Pena, L. D.; Basak, C.; Ferretti, P.

2017-12-01

North Atlantic Deep Water (NADW) represents the major water mass that drives the Atlantic Meridional Ocean Circulation (AMOC), which undergoes substantial reorganization with changing climate. In order to understand its impact on ocean circulation and climate through time, it is necessary to constrain its composition. We report Nd isotope ratios of Fe-Mn oxide encrusted foraminifera and fish debris from DSDP Site 607 (41.00N 32.96W, 3427m), in the present-day core of NADW, and ODP 1063 (33.68N 57.62W, 4585m), on the deep abyssal plain at the interface between NADW and Antarctic Bottom Water. We provide a new North Atlantic paleocirculation record covering 2 Ma. At Site 607 interglacial ɛNd-values are consistently similar to present-day NADW (ɛNd -13.5), with median ɛNd-values of -14.3 in the Early Pleistocene and -13.8 in the Late Pleistocene. Glacial ɛNd-values are higher by 1 ɛNd-unit in the Early Pleistocene, and 1.5-2 ɛNd-units in the Late Pleistocene. Site 1063 shows much greater variability, with ɛNd ranging from -10 to -26. We interpret the North Atlantic AMOC source as represented by the Site 607 interglacial ɛNd-values, which has remained nearly stable throughout the entire period. The higher glacial ɛNd-values reflect incursions of some southern-sourced waters to Site 607, which is supported by coeval shifts to lower benthic foraminiferal d13C. In contrast, the Site 1063 ɛNd-values do not appear to reflect the AMOC end-member, and likely reflects local effects from a bottom source. A period of greatly disrupted ocean circulation marks 950-850 Ma, which may have been triggered by enhanced ice growth in the Northern Hemisphere that began around 1.2 Ma, as suggested by possible input events of Nd from the surrounding cratons into the North Atlantic observed in Site 607. Interglacial AMOC only recovers to the previously observed vigor over 200 ka following the disruption, whereas further intensified SSW incursion into the deep North Atlantic come to characterize the mid-late Pleistocene glacial intervals.

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.

77 FR 3100 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-01-23

... on 8260-15A. The large number of SIAPs, Takeoff Minimums and ODPs, in addition to their complex... 31, Amdt 14 CANCELLED Cook, MN, Cook Muni, RNAV (GPS) RWY 13, Orig Cook, MN, Cook Muni, RNAV (GPS) RWY 31, Amdt 1 Ely, MN, Ely Muni, RNAV (GPS) RWY 12, Amdt 1 Ely, MN, Ely Muni, RNAV (GPS) RWY 30, Amdt...

76 FR 64005 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-10-17

.... The large number of SIAPs, Takeoff Minimums and ODPs, in addition to their complex nature and the need.... Part 97 is amended to read as follows: Effective 20 OCT 2011 Albert Lea, MN, Albert Lea Muni, RNAV (GPS) RWY 17, Amdt 2 Albert Lea, MN, Albert Lea Muni, RNAV (GPS) RWY 35, Amdt 1 Albert Lea, MN, Albert Lea...

Reduction in Surface Ocean Carbon Storage across the Middle Miocene

NASA Astrophysics Data System (ADS)

Babila, T. L.; Sosdian, S. M.; Foster, G. L.; Lear, C. H.

2017-12-01

During the Middle Miocene, Earth underwent a profound climate shift from the warmth of the Miocene Climatic Optimum (MCO; 14-17 Ma) to the stable icehouse of today during the Middle Miocene Climate transition (MMCT). Elevated atmospheric carbon dioxide concentrations (pCO2) revealed by boron isotope records (δ11B) link massive volcanic outputs of Columbia River Flood Basalts to the general warmth of MCO. Superimposed on the long-term cooling trend (MMCT) is a gradual pCO2 decline and numerous positive carbon isotope (δ13C) excursions that indicate dynamic variations in the global carbon cycle. Enhanced organic carbon burial via marine productivity, increased silicate weathering and volcanic emission cessation are each invoked to explain the drawdown of pCO2. To better constrain the oceanic role in carbon sequestration over the Middle Miocene detailed records of carbonate chemistry are needed. We present high resolution Boron/Calcium (B/Ca) and δ13C records in planktonic foraminifer T.trilobus spanning 12-17 Ma at ODP 761 (tropical eastern Indian Ocean) to document changes in surface ocean carbonate chemistry. An overall 30% increase in B/Ca ratios is expressed as two stepwise phases occurring at 14.7 and 13 Ma. Cyclic B/Ca variations are coherent with complimentary δ13C records suggesting a tight coupling between ocean carbonate chemistry parameters. Lower resolution B/Ca data at DSDP 588 (Pacific) and ODP 926 (Atlantic) corroborate the trends observed at ODP 761. We employ a paired approach that combines B/Ca (this study) to δ11B (Foster et al., 2012) and an ad hoc calibration to estimate changes in surface ocean dissolved inorganic carbon (DIC). We estimate a substantial decrease in surface ocean DIC spanning the Middle Miocene that culminates with modern day like values. This gradual decline in surface ocean DIC is coeval with existing deep-ocean records which together suggests a whole ocean reduction in carbon storage. We speculate that enhanced weathering rather than short term processes are responsible for mediating global carbon reservoirs over the Middle Miocene.

Tracking Soil Organic Carbon Transport to Continental Margin Sediments Using Soil-Specific Hopanoid Biomarkers: a Case Study From the Congo Fan (ODP Site 1075)

NASA Astrophysics Data System (ADS)

Cooke, M. P.; Talbot, H. M.; Eniola, O.; Zabel, M.; Wagner, T.

2007-12-01

The transport and subsequent deposition of terrestrially derived organic matter into the ocean is an important but poorly constrained aspect of the modern global carbon cycle. In regions associated with large river systems it is likely that the terrestrial input of organic carbon is much more complex than commonly considered and very difficult to trace based on established geochemical proxies. It is therefore important to develop proxies that target the movement and fate of this terrestrial organic material. The identification of bacteriohopanepolyol (BHP) biomarkers unique to soil derived organic carbon (SOC) has enabled the transport of SOC into aquatic sediments to be traced. The extreme recalcitrance of BHPs enables these source specific compounds to be used on recent and ancient sediments to identify periods of high and low SOC input into sediments. BHPs are bacterial membrane compounds with a high degree of structural variability. They are analogous to steroids in eukaryotes and have been identified in over half of all bacteria studied for their presence. BHPs have a wide range of over 40 functional groups on the side chain, with up to 6 functional groups in each structure, and with methylation and unsaturation over 100 total structures have been identified1. During the BHP analysis of a wide range of soils from around the world we consistently measure high levels adenosylhopane, known to originate from purple non-sulphur, nitrogen fixing and ammonia oxidising bacteria and 2-methyl adenosyl hopane (m/z 802)2, from nitrogen fixing bacteria. Only 3 lacustrine sediments with large SOC supply from their catchments areas have been found to contain these markers in a survey of over 40 different non-marine settings. Recent studies on Late Quaternary sediments from the Congo deep sea fan (OPD site 1075, approximately 2 km water depth) provide a strong case to expect markers for SOC3. An initial analysis of the core samples confirms the presence of soil specific BHP markers in each sample analyzed down to 89 m depth in addition to the presence of common sediment associated BHPs. Concentrations of soil markers are high in the upper sediment section down to about 49 m supporting the case for these molecular markers as novel proxies for SOC supply and burial. Distinct peaks of adenosyl and 2 methyl adenosyl hopane at about 200, 300 and 550 kyrs tentatively imply that the rate of terrestrial organic matter discharge from tropical Africa significantly increased at these times, possibly associated with periods of reduced soil stability in the Congo catchment. Analysis of the surface sediments from 4 other cores in close proximity to ODP site 1075 clearly shows that the percentage contribution of soil marker BHPs decreases with increasing distance from the river mouth, indicating that the river is the source of these BHPs. References 1. Rohmer, M. 1993. Pure and Applied Chemistry 65, 1293-1298. 2. Talbot, H.M., Rohmer, M., Farrimond, P., 2007. Rapid Communications in Mass Spectrometry (In press). 3. Holtvoeth, J., Wagner, T., Kolonic, S., 2005. Geochimica et Cosmochimica Acta, 69, 2031-2041.

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.

An 110 Ma Crocodilian-Bearing Vertebrate Assemblage Preserved Between Basalt Flows on a mid-Pacific Seamount, ODP Site 865, Allison Guyot

NASA Astrophysics Data System (ADS)

Firth, J. V.; Yancey, T.; Alvarez-Zarikian, C.

2006-12-01

Crocodilian teeth, fish teeth, scales, and bones, and teeth and bones of uncertain affinities occur within a mudstone deposit sandwiched between basalt flows at the base of ODP Hole 865A on Allison Guyot in the middle of the Pacific Ocean. Age control from large benthic foraminifers, Sr-isotope stratigraphy, and radiometric ages of the basalt place the age of this assemblage at 110 \\mp 1.2 Ma, or late Aptian/early Albian. This deposit contains the oldest known crocodilian remains in the Pacific Realm. The vertebrate-bearing interval lies within a 30 cm mudstone unit overlying lithified fossiliferous limestone and underlying fossiliferous clayey limestone. The surface of the lithified limestone contains fish scales, vertebrate teeth and bones, and a carapace of the ostracod Cytherella. The lower 17 cm of mudstone is the prime vertebrate-bearing layer. It has a fining-upwards grain size trend, and an upward increase in dark coloration. The sand sized fraction is primarily pelletal glauconite, pyrite and fish debris. Limestone clasts up to several mm in diameter occur through the lower portion, whereas the higher portion contains sand laminae. A pristine 1 cm long crocodilian tooth, along with several smaller crocodilian teeth from this interval, attest to the presence of a saltwater crocodilian within the lagoon of this drowned mid-Pacific atoll. Common and varied fish teeth include both slender forms for piercing and grasping mobile prey and blunt flat-topped forms for crushing and grinding hard-shelled bottom living organisms such as oysters. The crushing teeth resemble those of the modern Black Drum fish, a bottom feeder common in shallow coastal environments. Abundant fish scales include both heavy phosphatic ganoid scales, a type present on many Mesozoic fish, and thin flexible scales of a type present on most modern fish. Some teeth and bone fragments are currently unidentified, and may represent vertebrates other than fish or crocodilians. No calcareous fossils are found within this unit. The lower unit grades upwards into a 5 cm thick black organic mudstone consisting of mostly amorphous organic debris, colonial algae, and smaller amounts of terrestrial spores, carbonized plant debris, and amber. No vertebrate remains are observed within the black mudstone. This unit in turn grades upwards into an 8 cm unit of mudstone with a coarsening-upwards grain size trend. This upper 8 cm unit contains only rare vertebrate remains, but has numerous oyster fragments and abundant, well preserved, articulated ostracod shells. The ostracod assemblage consists entirely of Cytherella (Suborder Platycopina). The entire 30 cm unit contains common pyrite, glauconite, and plant debris, and lacks calcareous fossils except in the uppermost part. This, as well as the occurrence of abundant Cytherella indicate sediment deposition in a restricted marine environment with low oxygen conditions. This discovery represents possibly the only known record of mid-Cretaceous reptilian remains from the mid- Pacific region, and the entire fossil assemblage provides valuable data for understanding the history of biotic migrations across the Cretaceous Pacific oceanic island realm. The intercalations of basalt flows with restricted marine and terrestrial sediments can be found not only in this ODP drill core but in others around the Pacific and shows the possibility of future discoveries of this type by scientific drilling of old seamounts.

Quantification of subsurface pore pressure through IODP drilling

NASA Astrophysics Data System (ADS)

Saffer, D. M.; Flemings, P. B.

2010-12-01

It is critical to understand the magnitude and distribution of subsurface pore fluid pressure: it controls effective stress and thus mechanical strength, slope stability, and sediment compaction. Elevated pore pressures also drive fluid flows that serve as agents of mass, solute, and heat fluxes. The Ocean Drilling Program (ODP) and Integrated Ocean Drilling Program (IODP) have provided important avenues to quantify pore pressure in a range of geologic and tectonic settings. These approaches include 1) analysis of continuous downhole logs and shipboard physical properties data to infer compaction state and in situ pressure and stress, 2) laboratory consolidation testing of core samples collected by drilling, 3) direct downhole measurements using pore pressure probes, 3) pore pressure and stress measurements using downhole tools that can be deployed in wide diameter pipe recently acquired for riser drilling, and 4) long-term monitoring of formation pore pressure in sealed boreholes within hydraulically isolated intervals. Here, we summarize key advances in quantification of subsurface pore pressure rooted in scientific drilling, highlighting with examples from subduction zones, the Gulf of Mexico, and the New Jersey continental shelf. At the Nankai, Costa Rican, and Barbados subduction zones, consolidation testing of cores samples, combined with analysis of physical properties data, indicates that even within a few km landward of the trench, pore pressures in and below plate boundary décollement zones reach a significant fraction of the lithostatic load (λ*=0.25-0.91). These results document a viable and quantifiable mechanism to explain the mechanical weakness of subduction décollements, and are corroborated by a small number of direct measurements in sealed boreholes and by inferences from seismic reflection data. Recent downhole measurements conducted during riser drilling using the modular formation dynamics tester wireline tool (MDT) in a forearc basin ~50 km from the trench document hydrostatic pore pressures in the basin fill down to ~1500 mbsf, and illustrate a promising technique for obtaining pore pressure and stress magnitude. In the Gulf of Mexico, we used pore pressure penetrometers to measure severe overpressures (λ*=0.7); a comprehensive program of consolidation testing on recovered core samples confirms elevated pore pressures due to rapid sedimentation, reflecting disequilibrium compaction. Similarly, along the New Jersey continental shelf, analysis of porosity data from downhole logs and augmented by geotechnical testing of cores demonstrates elevated pore pressures in the shallow subsurface. In both offshore New Jersey and the Gulf of Mexico, integration of direct measurements, geotechnical testing, and hydrodynamic modeling illustrate how flow is focused along permeable layers to reduce effective stress and drive submarine landslides. In sum, pore pressure observations made through the ODP and IODP provide insight into how pore pressure controls the large-scale form of passive and active continental margins, how submarine landslides form, and provide strategies for engineering deep boreholes.

Interhemispheric teleconnections: Late Pliocene change in Mediterranean outflow water linked to changes in Indonesian Through-Flow and Atlantic Meridional Overturning Circulation, a review and update

NASA Astrophysics Data System (ADS)

Sarnthein, Michael; Grunert, Patrick; Khélifi, Nabil; Frank, Martin; Nürnberg, Dirk

2018-03-01

The ultimate, possibly geodynamic control and potential impact of changes in circulation activity and salt discharge of Mediterranean outflow waters (MOW) on Atlantic meridional overturning circulation have formed long-standing objectives in paleoceanography. Late Pliocene changes in the distal advection of MOW were reconstructed on orbital timescales for northeast Atlantic DSDP/ODP sites 548 and 982 off Brittany and on Rockall Plateau, supplemented by a proximal record from Site U1389 west off Gibraltar, and compared to Western Mediterranean surface and deep-water records of Alboran Sea Site 978. From 3.43 to 3.3 Ma, MOW temperatures and salinities form a prominent rise by 2-4 °C and 3 psu, induced by a preceding and coeval rise in sea surface and deep-water salinity and increased summer aridity in the Mediterranean Sea. We speculate that these changes triggered an increased MOW flow and were ultimately induced by a persistent 2.5 °C cooling of Indonesian Through-Flow waters. The temperature drop resulted from the northward drift of Australia that crossed a threshold value near 3.6-3.3 Ma and led to a large-scale cooling of the eastern subtropical Indian Ocean and in turn, to a reduction of African monsoon rains. Vice versa, we show that the distinct rise in Mediterranean salt export after 3.4 Ma induced a unique long-term rise in the formation of Upper North Atlantic Deep Water, that followed with a phase lag of 100 ky. In summary, we present evidence for an interhemispheric teleconnection of processes in the Indonesian Gateways, the Mediterranean and Labrador Seas, jointly affecting Pliocene climate.

Insights into North Atlantic deep water formation during the peak interglacial interval of Marine Isotope Stage 9 (MIS 9)

NASA Astrophysics Data System (ADS)

Mokeddem, Zohra; McManus, Jerry F.

2017-11-01

Foraminifera abundance and stable isotope records from ODP Site 984 (61.25°N, 24.04°W, 1648 m) in the North Atlantic are used to reconstruct surface circulation variations and the relative strength of the North Atlantic Deep Water (NADW) formation over the period spanning the peak warmth of Marine Interglacial Stage (MIS) 9e ( 324-336 ka). This interval includes the preceding deglaciation, Termination 4 (T4), and the subsequent glacial inception of MIS 9d. The records indicate a greatly reduced contribution of NADW during T4, as observed in more recent deglaciations. In contrast with the most recent deglaciation, the lack of a significant NADW signal extended from T4 well into the peak interglacial MIS 9e and persisted nearly until the transition to the subsequent glacial stage MIS 9d. Although NADW formation resumed during MIS 9e, only depths greater than 2000 m appear to have been ventilated. The poorly ventilated intermediate depth of Site 984 (<2000 m) may have resulted on one hand from a general reduction of deep water ventilation by NADW during the study interval or, on the other hand, from different pathways of the spread of newly formed NADW that bypassed the study location. The intermediate depths may have also been invaded by southern-sourced waters as the formation of intermediate depth NADW weakened. The absence of any significant NADW signal at the water depth of Site 984 during the climatic optimum contrasts sharply with subsequent interglacial peaks (MIS 5e and the Holocene). Despite the perturbed intermediate depth circulation, oceanic heat transport northeastward was not interrupted and may have contributed to the relatively mild interglacial conditions of MIS 9e.

Evidence for a dynamic East Antarctic ice sheet during the mid-Miocene climate transition

NASA Astrophysics Data System (ADS)

Pierce, Elizabeth L.; van de Flierdt, Tina; Williams, Trevor; Hemming, Sidney R.; Cook, Carys P.; Passchier, Sandra

2017-11-01

The East Antarctic ice sheet underwent a major expansion during the Mid-Miocene Climate Transition, around 14 Ma, lowering sea level by ∼60 m. However, direct or indirect evidence of where changes in the ice sheet occurred is limited. Here we present new insights on timing and locations of ice sheet change from two drill sites offshore East Antarctica. IODP Site U1356, Wilkes Land, and ODP Site 1165, Prydz Bay are located adjacent to two major ice drainage areas, the Wilkes Subglacial Basin and the Lambert Graben. Ice-rafted detritus (IRD), including dropstones, was deposited in concentrations far exceeding those known in the rest of the Miocene succession at both sites between 14.1 and 13.8 Ma, indicating that large amounts of IRD-bearing icebergs were calved from independent drainage basins during this relatively short interval. At Site U1356, the IRD was delivered in distinct pulses, suggesting that the overall ice advance was punctuated by short periods of ice retreat in the Wilkes Subglacial Basin. Provenance analysis of the mid-Miocene IRD and fine-grained sediments provides additional insights on the movement of the ice margin and subglacial geology. At Site U1356, the dominant 40Ar/39Ar thermochronological age of the ice-rafted hornblende grains is 1400-1550 Ma, differing from the majority of recent IRD in the area, from which we infer an inland source area of this thermochronological age extending along the eastern part of the Adélie Craton, which forms the western side of the Wilkes Subglacial Basin. Neodymium isotopic compositions from the terrigenous fine fraction at Site U1356 imply that the ice margin periodically expanded from high ground well into the Wilkes Subglacial Basin during periods of MMCT ice growth. At Site 1165, MMCT pebble-sized IRD are sourced from both the local Lambert Graben and the distant Aurora Subglacial Basin drainage area. Together, the occurrence and provenance of the IRD and glacially-eroded sediment at these two marine drill sites proximal to the Antarctic continent provide a previously undocumented record of dynamic ice margin change during the 14.1-13.8 Ma interval in three major East Antarctic drainage basins.

An Earth Summit in a Large General Education Oceanography Class

NASA Astrophysics Data System (ADS)

Dodson, H.; Prothero, W. A.

2001-12-01

An Earth Summit approach in UCSB's undergraduate physical oceanography course has raised student interest level while it also supports the course goals of increased learner awareness of the process of science, and critical analysis of scientific claims. At the beginning of the quarter, each group of students chooses a country to represent in the Earth Summit. During the course of the quarter, these groups relate each of the class themes to their chosen country. Themes include 1) ocean basins and plate tectonics, 2) atmospheres, oceans and climate, and 3) fisheries. Students acquire and utilize Earth data to support their positions. Earth data sources include the "Our Dynamic Planet" CDROM (http://oceanography.geol.ucsb.edu/ODP_Advert/odp_onepage.htm), NOAA's ocean and climate database (http://ferret.wrc.noaa.gov/las/), WorldWatcher CD (http://www.worldwatcher.northwestern.edu/) and JPL's Seawinds web site (http://haifung.jpl.nasa.gov/index.html). During the atmospheres, oceans and climate theme, students choose from 12 mini-studies that use various kinds of on-line Earth data related to important global or regional phenomena relevant to the course. The Earth datasets that the students access for their analysis include: winds; atmospheric pressure; ocean chemistry; sea surface temperature; solar radiation; precipitation, etc. The first group of 6 mini-studies focus on atmosphere and ocean, and are: 1) global winds and surface currents, 2) atmosphere and ocean interactions, 3) stratospheric ozone depletion, 4) El Nino, 5) Indian monsoon, and 6) deep ocean circulation. The second group focus on the Earth's heat budget and climate and are: 1) influence of man's activities on the climate, 2) the greenhouse effect, 3) seasonal variation and the Earth's heat budget, 4) global warming, 5) paleoclimate, and 6) volcanoes and climate. The students use what they have learned in these mini-studies to address atmospheric and climatic issues pertinent to their specific Earth Summit countries. For example, students representing the country of Chile might model their investigations after a)winds and surface currents, b)atmosphere and ocean interactions, c) stratospheric ozone depletion, d)El Nino; and/or e)volcanoes and climate. Please join the "Oceanography" interest group of DLESE to discuss, develop, and access oceanography related mini-studies that use earth data (http://oceanography.geol.ucsb.edu/dlese/wg_oceanog/Index.html). >http://oceanography.geol.ucsb.edu/AWP/Class_Info/GS-4/Labs/Labs Index.html

Diatom and silicoflagellate biostratigraphy for the late Eocene: ODP 1090 (sub-Antarctic Atlantic)

USGS Publications Warehouse

Barron, John A.; Bukry, David B.; Gersonde, Rainer

2014-01-01

Abundant and well-preserved diatoms and silicofl agellate assemblages are documented through a complete late Eocene sequence, ODP Hole 1090B, recovered from the southern Agulhas Ridge in the sub-Antarctic South Atlantic. A sequence of Cestodiscus (diatom) species occurrence events involving C. pulchellus var. novazealandica, C. fennerae, C. antarcticus, C. convexus, C. trochus, and C. robustus is tied with paleomagnetic stratigraphy and provides the basis of proposing a new diatom zonation for the latest middle Eocene to early Oligocene (~37.6–33.4 Ma) of the sub-Antarctic South Atlantic. Comparison with previously published diatom occurrence charts suggested this zonation should be applicable throughout the low latitude regions of the world’s oceans. Silicofl agellates belong to the Dictyocha hexacantha and the overlying Corbisema apiculata Zones. The late Eocene succession of silicofl agellate species is dominated by Naviculopsis (20–60%). Naviculopsis constricta and N. foliacea dominate the D. hexacantha Zone, followed by the N. constricta, then N. biapiculata in the C. apiculata Zone. Cold-water Distephanus is most abundant in the latest Eocene along with N. biapiculata. The tops of zonal guide fossils Dictyocha hexacantha and Hannaites quadria (both 36.6 Ma) and Dictyocha spinosa (37.1 Ma) are tied with paleomagnetic stratigraphy.

Defining quality for distal pancreatectomy: does the laparoscopic approach protect patients from poor quality outcomes?

PubMed

Baker, Marshall S; Sherman, Karen L; Stocker, Susan; Hayman, Amanda V; Bentrem, David J; Prinz, Richard A; Talamonti, Mark S

2013-02-01

Established systems for grading postoperative complications do not change the assigned grade when multiple interventions or readmissions are required to manage a complication. Studies using these systems may misrepresent outcomes for the surgical procedures being evaluated. We define a quality outcome for distal pancreatectomy (DP) and use this metric to compare laparoscopic distal pancreatectomy (LDP) to open distal pancreatectomy (ODP). Records for patients undergoing DP between January 2006 and December 2009 were reviewed. Clavien-Dindo grade IIIb, IV, and V complications were classified as severe adverse--poor quality--postoperative outcomes (SAPOs). II and IIIa complications requiring either significantly prolonged overall lengths of stay including readmissions within 90 days or more than one invasive intervention were also classified as SAPOs. By Clavien-Dindo system alone, 91 % of DP patients had either no complication or a low/moderate grade (I, II, IIIa) complication. Using our reclassification, however, 25 % had a SAPO. Patients undergoing LDP demonstrated a Clavien-Dindo complication profile identical to that for SDP but demonstrated significantly shorter overall lengths of stay, were less likely to require perioperative transfusion, and less likely to have a SAPO. Established systems undergrade the severity of some complications following DP. Using a procedure-specific metric for quality, we demonstrate that LDP affords a higher quality postoperative outcome than ODP.

Surgical approach and optic coherence tomographic evaluation of optic disc anomaly in association with serous macular detachment.

PubMed

Güven, Dilek; Balcıoğlu, Nihal; Türker, Cağrı; Baydar, Yasemin; Sendül, Yekta

2013-12-01

Serous macular detachment (SMD) may accompany optic disc pit (ODP) and cause visual loss if untreated. We want to present different therapeutic approaches and interesting optical coherence tomography (OCT) findings in three consecutive cases. In this case series, two patients with SMD and one patient with partial macular detachment and inferior retinal detachment accompanying ODP were evaluated before and after surgical intervention clinically and by spectral-domain OCT. The patients were 44 (case 1), 22 (case 2) and 24 (case 3) years old. Pars plana vitrectomy (PPV) + silicone oil + laser, PPV + sulfur hexafluoride gas (SF6) + laser and pneumatic retinopexy were applied, respectively. The patients were followed for 18, 15 and 14 months. Preoperative best-corrected visual acuities (BCVAs) were 5/100, 7/10 and counting fingers at 1 m. Vision improved in all cases with resolution of subretinal fluid. Final BCVAs were 3/10, 10/10 and 1/10, respectively. OCT images revealed optic disc anomaly details and changes after surgical intervention, photoreceptor outer segment alterations at the detached area and macular surface changes. Surgical intervention should be tailored individually in cases with SMD. OCT is efficient for in vivo evaluation of this pathological condition and anatomical outcomes of surgery.

Long-term outcomes of pars plana vitrectomy without internal limiting membrane peeling for optic disc pit maculopathy.

PubMed

Avci, R; Yilmaz, S; Inan, U U; Kaderli, B; Kurt, M; Yalcinbayir, O; Yildiz, M; Yucel, A

2013-12-01

To evaluate the results of surgical treatment of maculopathy secondary to congenital optic pit anomaly with pars plana vitrectomy (PPV), endolaser to the temporal edge of the optic disc and C3F8 tamponade without internal limiting membrane (ILM) peeling. Thirteen eyes of 12 patients with serous macular detachment and/or macular retinoschisis secondary to congenital optic disc pit (ODP) were included in the study. All eyes underwent PPV, posterior hyaloid removal, endolaser photocoagulation on the temporal margin of the optic disc and 12% C3F8 gas tamponade. Anatomic success and functional outcome determined retrospectively by optical coherence tomography and measurement of best corrected visual acuity (BCVA), respectively were the main outcome parameters. Two lines or more improvement in BCVA was obtained in 11 eyes and 6 of these eyes had 20/40 or better BCVA at the final visit. Subretinal or intraretinal fluid was completely resorbed postoperatively in 12 eyes but a little intraretinal fluid persisted in one eye at the 16-month follow-up. Better visual improvement was observed in patients treated by earlier surgical intervention. PPV, C3F8 gas tamponade and endolaser to the optic disc margin without ILM peeling may yield favourable results in the treatment of ODP maculopathy.

Technology Application of Environmental Friendly Refrigeration (Green Refrigeration) on Cold Storage for Fishery Industry

NASA Astrophysics Data System (ADS)

Rasta, IM; Susila, IDM; Subagia, IWA

2018-01-01

The application of refrigeration technology to postharvest fishery products is an very important. Moreover, Indonesia is a tropical region with relatively high temperatures. Fish storage age can be prolonged with a decrease in temperature. Frozen fish can even be stored for several months. Fish freezing means preparing fish for storage in low-temperature cold storage. The working fluid used in cold storage to cool low-temperature chambers and throw heat into high-temperature environments is refrigerant. So far refrigerant used in cold storage is Hydrochloroflourocarbons (HCFC) that is R-22. Chlor is a gas that causes ODP (Ozone Depleting Potential), while Flour is a gas that causes GWP (Global Warming Potential). Government policy began in 2015 to implement Hydrochloroflourocarbons Phase-Out Management Plan. Hydrocarbon (HC) is an alternative substitute for R-22. HC-22 (propane ≥ 99.5%) has several advantages, among others: environmentally friendly, indicated by a zero ODP value, and GWP = 3 (negligible), thermophysical property and good heat transfer characteristics, vapor phase density Which is low, and good solubility with mineral lubricants. The use of HC-22 in cold storage is less than R-22. From the analysis results obtained, cold storage system using HC-22 has better performance and energy consumption is more efficient than the R-22.

Magnetic Properties of Bermuda Rise Sediments Controlled by Glacial Cycles During the Late Pleistocene

NASA Astrophysics Data System (ADS)

Roud, S.

2015-12-01

Sediments from ODP site 1063 (Bermuda Rise, North Atlantic) contain a high-resolution record of geomagnetic field behavior during the Brunhes Chron. We present rock magnetic data of the upper 160 mcd (<900 ka) from hole 1063D that show magnetic properties vary in concert with glacial cycles. Magnetite appears to be the main magnetic carrier in the carbonate-dominated interglacial horizons, yet exhibits contrasting grain size distributions depending on the redox state of the horizons. Higher contributions of single domain magnetite exist above the present day sulfate reduction zone (ca. 44 mcd) with relatively higher multidomain magnetite components below that likely arise from the partial dissolution of SD magnetite in the deeper, anoxic horizons. Glacial horizons on the other hand, characterized by enhanced terrigenous deposition, show no evidence for diagenetic dissolution but do indicate the presence of authigenic greigite close to glacial maxima (acquisition of gyro-remanence, strong magnetostatic interactions and SD properties). Glacial horizons contain hematite (maxima in HIRM and S-Ratio consistent with a reddish hue) and exhibit higher ARM anisotropy and pronounced sedimentary fabrics. We infer that post depositional processes affected the magnetic grain size and mineralogy of Bermuda rise sediments deposited during the late Pleistocene. Hematite concentration is interpreted to reflect primary terrigenous input that is likely derived from the Canadian Maritime Provinces. A close correlation between HIRM and magnetic foliation suggests that changes in sediment composition (terrigenous vs. marine biogenic) were accompanied by changes in the depositional processes at the site.

Widespread Mega-Pockmarks Imaged Along the Western Edge of the Cocos Ridge

NASA Astrophysics Data System (ADS)

Gibson, J. C.; Kluesner, J. W.; Silver, E. A.; Bangs, N. L.; McIntosh, K. D.

2012-12-01

A large field (245km2) of 31 seabed mega-pockmarks was imaged between the Cocos ridge and the Quepos plateau on ~16.5 Ma oceanic crust generated at the Cocos-Nazca spreading center. The imaged pockmarks represent only a fraction of the much larger pockmark field evident in 100 m grid cell bathymetry data secured from MGDS. The pockmarks are clustered around 1800-2100 mbsl and were mapped using EM122 multibeam sonar, a 3.5 kHz sub-bottom profiler, and 3D Multi-Channel Seismic (MCS) aboard R/V Marcus G. Langseth during the CRISP seismic survey (2011). Using a constrained swath width of 1.4 km, the increased sounding density facilitated bathymetry/backscatter to be gridded at 10m and 8m respectively. The diameter of the pockmarks varies from ~1 km to ~2 km with a relief range of ~30-80 m, and average slopes of 15°. The MCS data also reveal older buried pockmarks in trench adjacent sediments. Small high-backscatter mounds occur within a subset of the pockmarks, which may indicate bioherms or carbonate banks above focused fluid flow conduits. Based on drilling results of DSDP Site 158 and ODP Site 1381, the pockmarks appear to be the result of paleo-differential advancement of a silica diagenetic front (opal-A to opal-CT). Although, the pockmarks may be erosional features sourced at depth from dewatering of sediments inter-bedded with igneous layers.

Iridium and Spherules in Late Eocene Impact Deposits

NASA Technical Reports Server (NTRS)

Kyte, F. T.; Liu, S.

2002-01-01

We have been independently examining the Ir (FTK) and spherule (SL) contents of recently discovered late Eocene impact deposits from the south Atlantic and western Indian oceans. These include ODP Sites 1090 [14,15], 709 [lo], and 699 [Liu in prep.]. Iridium abundances at these sites are within the typical range reported for late Eocene deposits, with peak concentrations between 100 and 1000 pg/g. In Table 1 we present estimated net Ir fluences (in ng Ir/cm ) for these and nine other sites. Although there are fewer sites than the K/T boundary, the average of 9 ng Ir/cm2 is probably a good estimate of the late Eocene global flux. This is enough Ir for a 6 km comet (assuming 250 ng/g Ir, p=1.5), is sufficient to produce the Popigai or Chesapeake Bay structures, and is 16% of the flux estimated for the K/T boundary (55 ng/cm2 [ 161). Figure 1 shows the relative abundances of Ir, glassy microtektites and cpx-bearing spherules in sediments from Sites 699 and 1090, which are separated by only 3100 km. Although these two sites have similar Ir anomalies, the abundances of spherules are quite different. Site 1090 has well-defined peaks for both types of spherules, with a peak of 562 cpx spheruledg, while Site 699 contains only a few glassy microtektites and no cpx spherules. While the different abundances of spherules may reflect a heterogeneous distribution of spherules on the Earth s surface, an equally likely cause of this difference may be differential preservation of spherules in the sediment. recovered are only a trace residue of the initial impact deposit. Earlier work found 0.22 ng/g Ir in glassy microtektites from Site 689 [17], an insufficient concentration to support 0.16 ng/g in the bulk sediment at this site. We measured 15 ng/g Ir in a group of 95 cpx spherules from Site 1090 with sizes from 63 to -200 pm, a set typical of the size distribution at this site. Although this is a significant concentration it also cannot support the Ir peak. We presently lack quantitative data on the mass concentration of cpx spherules in Site 1090 sediments, but it is certainly <1 mg/g in The impact record in the late Eocene is very different from that at the Cretaceous-Tertiary In contrast, the late Eocene probably experienced multiple impact events.

Teaching Marine Geoscience at Sea: Integrated Ocean Drilling Program's School of Rock Explores Cascadia Subduction Zone - Cores, Logs, and ACORKs

NASA Astrophysics Data System (ADS)

Reagan, M.; Collins, J.; Ludwig, K. A.; Slough, S.; Delaney, M. L.; Hovan, S. A.; Expedition 328 Scientists

2010-12-01

For twelve days this past September, seventeen formal and informal educators from the US, UK, and France joined six instructors and a small science party on the scientific drillship JOIDES Resolution for the Integrated Ocean Drilling Program (IODP)’s Cascadia ACORK Expedition. The educators were part of the annual “School of Rock (SOR)” education program. SOR is coordinated by the U.S. Implementing Organization (USIO) of IODP and is designed to engage participants in seagoing Earth systems research and education workshops onboard the JOIDES Resolution and on shore at the Gulf Coast Core Repository in Texas. The scientific objective of the Cascadia ACORK expedition was to install a new permanent hydrologic observatory at ODP Site 889 to provide long-term monitoring of the pressure at the frontal part of the Cascadia accretionary prism. This year’s SOR workshop focused on how cores, logs, and ACORKs shed light on the hydrology and geology of the Cascadia subduction zone in the Northeast Pacific. In addition to observing the deployment of the ACORK, the SOR participants conducted daily hands-on analyses of archived sediment and hard-rock cores with scientists and technicians who specialize in IODP research using the lab facilities on the ship. Throughout the expedition, participants engaged in different activities and lessons designed to explore the deep biosphere, methane hydrates, paleoceanography, sedimentology, biostratigraphy, seafloor spreading, and drilling technology. The workshop also provided participants with “C3” time; time to communicate their experience using the successful joidesresolution.org website and other tools, make connections to their prior knowledge and expertise, and to be creative in developing and planning new education and outreach activities based on their new knowledge and research. As part of participating in the expedition, participants committed to further developing and testing their education and outreach products after the expedition, conducting post-expedition projects in conjunction with the U.S. Implementing Organization and their own institutions, and to participating actively in post-cruise evaluation. Since its inception in 2005, 75 SOR graduates and staff have conducted over 150 workshops and short courses for 3,000 participants in more than 30 U.S. states and five other nations. Integral to the success of the program is the evaluation process that takes place during and after each SOR. In particular, SOR evaluations take advantage of the power of video data collection to demonstrate the transformative nature of SOR expeditions. Video evaluations offer a unique opportunity to collect and preserve participant “voice” to document true transformative broader impacts. Along with video evaluations, the program also employs more traditional evaluation methods such as internal evaluator observations, open-ended questionnaires, and participant journals.

Widely Dispersed Tephra of Toba Mega-Eruptions in the Indian Ocean

NASA Astrophysics Data System (ADS)

Chen, C.; Lee, M.; Iizuka, Y.; Dehn, J.; Song, S.; Yang, F.

2001-12-01

The tephra layers recovered in the Quaternary sediments of Ocean Drilling Program (ODP) Leg 121 Site 758 provide the best record of Toba mega-eruptions in Sumatra, Indonesia. Site 758, located at 5o23.05¡œN, 90o21.67¡œE on the crest of Ninetyeast Ridge with 2924 m water depth, is approximately 1000 km west from the Toba caldera. Four tephra layers in the last 1.5 Ma were recognized as the products of the Toba caldera eruptions, based on chemical and isotopic compositions of the glass shards and minerals. These four tephra layers are named as A, C, D and F layers by Dehn et al. (1991), respectively. The glass shards in these tephra layers related to Toba eruptions showed much higher K2O (>4.5%) and lower CaO (<0.8%) contents, therefore pointing out great differences from the corresponding values of other ashes originating in the Philippines (e.g. glass in the SCS from Mt Pinatubo, K2O<3.0% and CaO>1.1%, SiO2 ~77% Wiesner et al., 1995). Moreover, the biotite grains in these tephra layers showed that the FeO content was higher than the MgO content. The isotopic composition of glass shards is the best fingerprint to trace the source rock. The glass shard fragments revealed extremely high 87Sr/86Sr values (0.71384-0.71869); As for the Sr isotopic values, the Youngest Toba Tuff (YTT) and the Oldest Toba Tuff (OTT) in the Sumatra and the IMAGES Cores in the South China Sea also showed high values from 0.7128-0.7152 (Chesner, 1988; Song et al., 2000; Chen et al., 2000, 2001). The tephrochronology of four tephra layers was re-estimated, based on the new Oxygen proxies. The ages of the A, C, D and F layers in the Site 758 were 0.075 Ma, 0.49 Ma, 0.80 Ma and 1.41 Ma, respectively, which could well correspond to the YTT, the Middle Toba Tuff (MTT), the OTT and the Haranggoal Dacite Tuff (HDT), respectively. This unique set of four wildly dispersed ash layers in the Indian Ocean will provide not only the important key beds in marine sedimentary sequence study in the Quaternary era, but a rare chance to speculate the relationship between the mega-eruptions and the long term global climate change in the natural laboratory.

Taxonomy of quaternary deep-sea ostracods from the Western North Atlantic ocean

USGS Publications Warehouse

Yasuhara, Moriaki; Okahashi, H.; Cronin, T. M.

2009-01-01

Late Quaternary sediments from Ocean Drilling Program (ODP) Hole 1055B, Carolina Slope, western North Atlantic (32??47.041??? N, 76??17.179??? W; 1798m water depth) were examined for deep-sea ostracod taxonomy. A total of 13933 specimens were picked from 207 samples and c. 120 species were identified. Among them, 87 species were included and illustrated in this paper. Twenty-eight new species are described. The new species are: Ambocythere sturgio, Argilloecia abba, Argilloecia caju, Argilloecia keigwini, Argilloecia robinwhatleyi, Aversovalva carolinensis, Bythoceratina willemvandenboldi, Bythocythere eugeneschornikovi, Chejudocythere tenuis, Cytheropteron aielloi, Cytheropteron demenocali, Cytheropteron didieae, Cytheropteron richarddinglei, Cytheropteron fugu, Cytheropteron guerneti, Cytheropteron richardbensoni, Eucytherura hazeli, Eucytherura mayressi, Eucytherura namericana, Eucytherura spinicorona, Posacythere hunti, Paracytherois bondi, Pedicythere atroposopetasi, Pedicythere kennettopetasi, Pedicythere klothopetasi, Pedicythere lachesisopetasi, Ruggieriella mcmanusi and Xestoleberis oppoae. Taxonomic revisions of several common species were made to reduce taxonomic uncertainty in the literature. This study provides a robust taxonomic baseline for application to palaeoceanographical reconstruction and biodiversity analyses in the deep and intermediate-depth environments of the North Atlantic Ocean. ?? The Palaeontological Association, 2009.

Chromite oxidation by manganese oxides in subseafloor basalts and the presence of putative fossilized microorganisms.

PubMed

Ivarsson, Magnus; Broman, Curt; Holm, Nils G

2011-06-03

Chromite is a mineral with low solubility and is thus resistant to dissolution. The exception is when manganese oxides are available, since they are the only known naturally occurring oxidants for chromite. In the presence of Mn(IV) oxides, Cr(III) will oxidise to Cr(VI), which is more soluble than Cr(III), and thus easier to be removed. Here we report of chromite phenocrysts that are replaced by rhodochrosite (Mn(II) carbonate) in subseafloor basalts from the Koko Seamount, Pacific Ocean, that were drilled and collected during the Ocean Drilling Program (ODP) Leg 197. The mineral succession chromite-rhodochrosite-saponite in the phenocrysts is interpreted as the result of chromite oxidation by manganese oxides. Putative fossilized microorganisms are abundant in the rhodochrosite and we suggest that the oxidation of chromite has been mediated by microbial activity. It has previously been shown in soils and in laboratory experiments that chromium oxidation is indirectly mediated by microbial formation of manganese oxides. Here we suggest a similar process in subseafloor basalts.

Chromite oxidation by manganese oxides in subseafloor basalts and the presence of putative fossilized microorganisms

PubMed Central

2011-01-01

Chromite is a mineral with low solubility and is thus resistant to dissolution. The exception is when manganese oxides are available, since they are the only known naturally occurring oxidants for chromite. In the presence of Mn(IV) oxides, Cr(III) will oxidise to Cr(VI), which is more soluble than Cr(III), and thus easier to be removed. Here we report of chromite phenocrysts that are replaced by rhodochrosite (Mn(II) carbonate) in subseafloor basalts from the Koko Seamount, Pacific Ocean, that were drilled and collected during the Ocean Drilling Program (ODP) Leg 197. The mineral succession chromite-rhodochrosite-saponite in the phenocrysts is interpreted as the result of chromite oxidation by manganese oxides. Putative fossilized microorganisms are abundant in the rhodochrosite and we suggest that the oxidation of chromite has been mediated by microbial activity. It has previously been shown in soils and in laboratory experiments that chromium oxidation is indirectly mediated by microbial formation of manganese oxides. Here we suggest a similar process in subseafloor basalts. PMID:21639896

Reaction of propane with the ordered NiO/Rh(1 1 1) studied by XPS and LEISS

NASA Astrophysics Data System (ADS)

Zhang, Hong; Wang, Wenyi; Chen, Mingshu; Wan, Huilin

2018-05-01

Nickel oxide has been reported to be an efficient catalyst for oxidative dehydrogenation of propane (ODP) to propene at low temperature. In this paper, ultrathin NiO films with various thickness were prepared on a Rh(1 1 1) surface and characterized by X-ray photoemission spectroscopy (XPS) and Low-energy ion scattering spectroscopy (LEISS). Results show that NiO forms a two-dimensional (2D) network with a O-Ni-O structure at submonolayer coverages, and a bulk-like NiO at multilayer coverages. The submonolayer NiO films are less stable than the thick ones when annealed in ultra-high vacuum (UHV) due to the strong interaction with the Rh substrate. Propane was dosed onto the model surfaces at different temperatures to investigate the activation of propane and reactivity of NiO films with propane. The reactions of propane with the thin and thick NiO films are significantly different. Propane activates on the O defect sites for the thick NiO films, whereas activation occurs on the interface of nickel oxide and substrate for the thin films with a higher activity.

Towards an Accurate Orbital Calibration of Late Miocene Climate Events: Insights From a High-Resolution Chemo- and Magnetostratigraphy (8-6 Ma) from Equatorial Pacific IODP Sites U1337 and U1338

NASA Astrophysics Data System (ADS)

Drury, A. J.; Westerhold, T.; Frederichs, T.; Wilkens, R.; Channell, J. E. T.; Evans, H. F.; Hodell, D. A.; John, C. M.; Lyle, M. W.; Roehl, U.; Tian, J.

2015-12-01

In the 8-6 Ma interval, the late Miocene is characterised by a long-term -0.3 ‰ reduction in benthic foraminiferal δ18O and distinctive short-term δ18O cycles, possibly related to dynamic Antarctic ice sheet variability. In addition, the late Miocene carbon isotope shift (LMCIS) marks a permanent long-term -1 ‰ shift in oceanic δ13CDIC, which is the largest, long-term perturbation in the global marine carbon cycle since the mid Miocene Monterey excursion. Accurate age control is crucial to investigate the origin of the δ18O cyclicity and determine the precise onset of the LMCIS. The current Geological Time Scale in the 8-6 Ma interval is constructed using astronomical tuning of sedimentary cycles in Mediterranean outcrops. However, outside of the Mediterranean, a comparable high-resolution chemo-, magneto-, and cyclostratigraphy at a single DSDP/ODP/IODP site does not exist. Generating an accurate astronomically-calibrated chemo- and magneto-stratigraphy in the 8-6 Ma interval became possible with retrieval of equatorial Pacific IODP Sites U1337 and U1338, as both sites have sedimentation rates ~2 cm/kyr, high biogenic carbonate content, and magnetic polarity stratigraphies. Here we present high-resolution correlation of Sites U1337 and U1338 using Milankovitch-related cycles in core images and X-ray fluorescence core scanning data. By combining inclination and declination data from ~400 new discrete samples with shipboard measurements, we are able to identify 14 polarity reversals at Site U1337 from the young end of Chron C3An.1n (~6.03 Ma) to the onset of Chron C4n.2n (~8.11 Ma). New high-resolution (<1.5 kyr) stable isotope records from Site U1337 correlate highly with Site U1338 records, enabling construction of a high-resolution stack. Initial orbital tuning of the U1337-U1338 records show that the δ18O cyclicity is obliquity driven, indicating high-latitude climate forcing. The LMCIS starts ~7.55 Ma and is anchored in Chron C4n.1n, which is comparable to the north and equatorial Atlantic.

Interprofessional collaborative teamwork facilitates patient centred care: a student practitioner's perspective.

PubMed

Osbiston, Mark

2013-05-01

Interprofessional teamwork and collaboration are essential for facilitating perioperative patient centred care. Operating department practitioners (ODPs) and nurses are registered professional 'practitioner' members of the perioperative team. Standards of conduct, communication skills, ethical principles and confidentiality legislation associated with documented patient information underpin and guide perioperative practitioner practice. This article will discuss, from a student's theoretical and practice experience perspective, the registered professional 'practitioner' role in the context of the interprofessional team.

Online Classroom Research and Analysis Activities Using MARGINS-Related Resources for the Izu-Bonin-Mariana Subduction System

NASA Astrophysics Data System (ADS)

Ryan, J. G.

2007-12-01

Students today have online access to nearly unlimited scientific information in an entirely unfiltered state. As such, they need guidance and training in identifying and assessing high-quality information resources for educational and research use. The extensive research data resources available online for the Izu-Bonin-Mariana (IBM) subduction system that have been developed with MARGINS Program and related NSF funding are an ideal venue for focused Web research exercises that can be tailored to a range of undergraduate geoscience courses. This presentation highlights student web research activities examining: a) The 2003-2005 eruptions of Anatahan Volcano in the Mariana volcanic arc. MARGINS-supported geophysical research teams were in the region when the eruption initiated, permitting a unique "event response" data collection and analysis process, with preliminary results presented online at websites linked to the MARGINS homepage, and ultimately published in a special issue of the Journal of Volcanology and Geothermal Research. In this activity, students will conduct a directed Web surf/search effort for information on and datasets from the Anatahan arc volcano, which they will use in an interpretive study of recent magmatic activity in the Mariana arc. This activity is designed as a homework exercise for use in a junior-senior level Petrology course, but could easily be taken into greater depth for the benefit of graduate-level volcanology or geochemistry offerings. b) Geochemical and mineralogical results from ODP Legs 125 and 195 focused on diapiric serpentinite mud volcanoes, which erupt cold, high pH fluids, serpentine muds, and serpentinized ultramafic clasts at a number of sites in the forearc region of the Mariana subduction zone. The focus of this activity is an examination of the trace element chemistry of the forearc serpentines and their associated upwelling porefluids as a means of understanding the roles of ionic radius, valence, and system abundance in the formation and trace element systematics of serpentine group minerals.

Cooling rates and the depth of detachment faulting at oceanic core complexes: Evidence from zircon Pb/U and (U-Th)/He ages

USGS Publications Warehouse

Grimes, Craig B.; Cheadle, Michael J.; John, Barbara E.; Reiners, P.W.; Wooden, J.L.

2011-01-01

Oceanic detachment faulting represents a distinct mode of seafloor spreading at slow spreading mid-ocean ridges, but many questions persist about the thermal evolution and depth of faulting. We present new Pb/U and (U-Th)/He zircon ages and combine them with magnetic anomaly ages to define the cooling histories of gabbroic crust exposed by oceanic detachment faults at three sites along the Mid-Atlantic Ridge (Ocean Drilling Program (ODP) holes 1270D and 1275D near the 15??20???N Transform, and Atlantis Massif at 30??N). Closure temperatures for the Pb/U (???800??C-850??C) and (U-Th)/He (???210??C) isotopic systems in zircon bracket acquisition of magnetic remanence, collectively providing a temperature-time history during faulting. Results indicate cooling to ???200??C in 0.3-0.5 Myr after zircon crystallization, recording time-averaged cooling rates of ???1000??C- 2000??C/Myr. Assuming the footwalls were denuded along single continuous faults, differences in Pb/U and (U-Th)/He zircon ages together with independently determined slip rates allow the distance between the ???850??C and ???200??C isotherms along the fault plane to be estimated. Calculated distances are 8.4 ?? 4.2 km and 5.0 2.1 km from holes 1275D and 1270D and 8.4 ?? 1.4 km at Atlantis Massif. Estimating an initial subsurface fault dip of 50 and a depth of 1.5 km to the 200??C isotherm leads to the prediction that the ???850??C isotherm lies ???5-7 km below seafloor at the time of faulting. These depth estimates for active fault systems are consistent with depths of microseismicity observed beneath the hypothesized detachment fault at the TAG hydrothermal field and high-temperature fault rocks recovered from many oceanic detachment faults. Copyright 2011 by the American Geophysical Union.

Highly Effective, Low Toxicity, Low Environmental Impact Total Flooding Fire Suppressants

NASA Technical Reports Server (NTRS)

Glass, S. M.; Dhooge, P. M.; Nimitz, J. S.

2001-01-01

Halon 1301 (CF3Br) has been used for decades as the primary fire suppression agent for areas where powder agents cannot be used because of concerns for sensitive equipment. Halon 1301 is an excellent extinguishing agent, effective at about 3% in air and quite non-toxic. It has an effective exposure limit much greater than its extinguishing concentration, so it can be used in normally occupied areas. The ability of a chemical to destroy stratospheric ozone is its ozone-depletion potential (ODP). ODP is the amount of ozone destroyed per pound of a chemical, relative to the standard CFC-11 with an ODP = 1.0. Because halons have been implicated in stratospheric ozone depletion, their production was stopped at the end of 1995 under the provisions of the Montreal Protocol plus later amendments. In the US, the Clean Air Act Amendments of 1990, Presidential directives, and DoD Directive 6050.9 implemented this phaseout. These regulations and penalties have provided strong incentives for US businesses to decrease CFC use. The Omnibus Budget Reconciliation Act of 1989 mandates high Federal taxes on CFCs and halons, designed to price them out of the market. The taxes also capture for the government the windfall profits that would otherwise go to producers as scarcity drives up prices. Several replacements have been developed for Halon 1301. One is carbon dioxide, which has been used as a firefighting agent for many years. However, a high concentration of carbon dioxide is necessary to inert fuels. The effective concentration for inerting with carbon dioxide is approximately 29%, which is above the concentration lethal to humans. HFC-227ea is being used extensively to replace Halon 1301 systems in nominally occupied areas and some normally unoccupied areas. However, since the effective concentration of HFC-227ea is about three to four times that of Halon 1301 the extinguishing systems have to be larger and new extinguishing systems have to be installed. HFC-125 is also being sold as an extinguishing agent (Nimitz). It has problems similar to HFC-227ea, with a greater concentration needed for effectiveness and the need to use a larger system. This is a particularly onerous penalty in aircraft and spacecraft, where weight and space are extremely important, and substitution is often impossible in existing aircraft due to space limitations.

Evidence of Himalayan uplift as seen in Neogene records of Indian monsoon variability from ODP Hole 722B, NW Arabian Sea

NASA Astrophysics Data System (ADS)

Muthusamy, Prakasam; Gupta, Anil K.; Saini, Naresh K.

2013-04-01

The Indian monsoon is one of the most interesting climatic features on Earth impacting most populous countries of South and East Asia. It is marked by seasonal reversals of wind direction with southwesterly winds in summer (June-September) and northeasterly winds in winter (December-February). The monsoon not only impacts socioeconomic conditions of Asia but also brings important changes in fauna and flora, ocean upwelling and primary productivity in the Arabian Sea. The Himalaya has undergone several phases of rapid uplift and exhumation since the early Miocene which led to major intensification of the Indian monsoon. The monsoon is driven by the thermal contrast between land and sea, and is intimately linked with the latitudinal movement of the Inter-Tropical Convergence Zone (ITCZ). The effect of Indian monsoon variability and the Himalayan uplift can be seen in numerous proxy records across the region. In this study we discussed about the Indian monsoon intensification and the Himalayan uplift since the early Miocene based on multi proxy records such as planktic foraminiferal relative abundances (Globigerina bulloides, Globigerinita glutinata and mixed layer species), total organic carbon (TOC), CaCO3 and elemental data from ODP Hole 722B (2028 mbsf), northwestern Arabian Sea. The TOC, CaCO3 and elemental variations of the ODP Hole 722B suggest multi phase of monsoonal intensification and Himalayan uplifts. Our results suggest that in the early Miocene (23.03 Ma) to ~15Ma, the wind strength and productivity were low. A major change is observed at ~15 Ma, during which time numerous proxies show abrupt changes. TOC, CaCO3 and Elemental analyses results reveal that a major change in the productivity, wind strength and chemical weathering starts around 15 Ma and extends up to 10 Ma. This suggests that a major Himalayan uplift occurred during ~15-10 Ma that drove Indian monsoon intensification. A similar change is also observed during 5 to 1 Ma. These long-term paleoclimatic trends correlated to Himalayan uplift. Major peaks in various proxy records correspond with enhanced monsoonal strength and the Himalayan uplift. Keywords: Indian monsoon; Himalayan uplift; Arabian Sea; Productivity; Planktic foraminifera; Total Organic Carbon

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.

The timing of events surrounding the Eocene-Oligocene boundary - Results from ODP Leg 199

NASA Astrophysics Data System (ADS)

Pälike, H.; Wilson, P. A.; Coxall, H.; Backman, J.

2003-04-01

The Eocene/Oligocene (E/O) boundary represents an extreme and rapid climatic transition from the ``greenhouse'' world of the Cretaceous and early Paleogene into the late Paleogene-Neogene ``ice-house''. It is marked by a large and global deepening in the calcite compensation depth (CCD), as well as pronounced changes in the isotopic composition of carbon and oxygen in seawater, recorded in biogenic calcium carbonate. A good understanding is still lacking as to why climatic, palaeoceanographic and marine biological productivity changes occurred within a few tens of thousands of years, and what change in boundary conditions triggered a non-linear response of the climate system. Detailed palaeoceanographic records surrounding the E/O have been rare because of the lack of well-dated, expanded deep-sea sedimentary sections containing well-preserved calcareous microfossils. Ocean Drilling Program Leg 199 recently recovered an extensive set of high-quality sediment cores across the E/O that span a latitudinal and depth transect in the central Pacific Ocean. We present new high-resolution records of bulk %CaCO3, δ18O and δ13C for a set of sites that form a depth transect, clearly delineating the relative depth with respect to the CCD during the transition. Our data show that a two-stepped deepening of the CCD coincides with a remarkably similar and simultaneous evolution of bulk δ18O values. We can demonstrate the imprint of climatic cycles around the E/O boundary, and very high-quality bio- and paleomagnetic datum points allow us to link these to Earth's orbital variations. Shipboard measurements of sediment properties and down-hole log measurements also display an imprint of climatic cycles, and allow us to obtain an astronomically calibrated time scale across the E/O. Our results put tighter constraints on the timing of the evolution of the CCD, mass accumulation rates, and biological productivity across the E/O, which display a distinct two-step shift in the most expanded section at the shallowest end of the transect (Site 1218). The initial deepening of the CCD occurred in less than 50 thousand years, and we observe a change in the nature and amplitude of climatic cycles that are recorded in sediments from Leg 199 across the E/O.

Deglacial Dust Provenance Changes in the Eastern Equatorial Pacific and Implications for ITCZ Movement

NASA Astrophysics Data System (ADS)

Xie, R.; Marcantonio, F.

2009-12-01

The provenance of the eolian dust component of deep-sea sediments has the potential to offer insights into changes in past atmospheric circulation patterns. Measuring temporal changes in dust provenance can shed more light on changes in the position of the Intertropical Convergence Zone (ITCZ), a region in which dust is removed from the upper troposphere by deep convection and scavenged by precipitation. The ITCZ should, therefore, act as a barrier separating wind-blown northern versus southern sources. Perhaps the best way to trace for provenance of dust sources is through the measurement of radiogenic isotope ratios. Here, we have analyzed Nd, Sr, and Pb isotope ratios in the detrital components extracted from deep-sea sediments in the eastern equatorial Pacific (EEP) along a meridional transect at 110W from 3S to 7N (ODP Leg 138, Sites 848 - 853). At each site, the sediments ranged in age from 0 to 25 ka. Detrital component extraction involved the chemical removal of the biogenic and authigenic sedimentary fractions. Preliminary detrital Nd isotope ratios show a range of 2.4 ɛNd units (from -5.7 to -3.3). There are distinct latitudinal trends in the ɛNd values, with more radiogenic values further south and less radiogenic values further north. This distinction holds true for both Holocene and glacial time. The difference in Nd isotope ratios at any one site between Holocene and glacial is smaller for the sites furthest North. The greatest Holocene-glacial differences in ɛNd occur at sites south of 3N, suggesting a distinct detrital component boundary at this latitude. The sites furthest north (7N and 5.29N) show the greatest variability in detrital 87Sr/86Sr isotope ratios, while sites furthest south (equator and 1.5N) show negligible variability. The detrital component of sediment at Site 851 (2.77N) has a Sr isotope variability that is intermediate between the northern and southern values, again suggesting a detrital boundary of some sort. We interpreted these preliminary results to suggest that the ITCZ position was displaced toward the south, with a paleo-position located between Site 851 (2.77N) and Site 852 (5.29N), from its average current location, which is approximately 7N. This supports one hypothesis put forward by McGee et al. [1], based on changes in dust flux for the same transect, that the ITCZ was displaced toward the south during the last glacial period. [1] McGee et al., 2007, EPSL 257, 215-230 .

Changes in In Situ Stress Across the Nankai and Cascadia Convergent Margins From Borehole Breakout Measurements During Ocean Drilling

NASA Astrophysics Data System (ADS)

McNeill, L.; Moore, J. C.; Yamada, Y.; Chang, C.; Tobin, H.; Kinoshita, M.; Gulick, S.; Moore, G.; Iodp Exp. 314/315/316 Science Party, &

2008-12-01

Borehole breakouts are commonly observed in borehole images shortly after drilling of continental margin sites. This study aims to compile and compare these results to determine what in situ shallow stress measurements can tell us about the larger scale tectonic regime. Recent Logging While Drilling resistivity images across the Kumano transect of the Nankai subduction zone, during Expedition 314, Stage 1 of the IODP NanTroSEIZE project, add to this dataset. Expedition 314 site data within the prism (C0001, C0004, C0006, including the megasplay fault system which may overlie the seismogenic updip limit) suggest maximum compressive stress (SHmax) is perpendicular to the margin (not parallel to the convergence vector) but is rotated through 90° at the forearc basin site (C0002). These results may point to changes in stress state of the shallow forearc from east to west: compression in the aseismic active prism (with evidence of strain partitioning of oblique convergence); and extension above the updip seismogenic zone suggesting focus of plate coupling at the plate boundary and not in the shallow forearc. Further south, ODP Leg 196 drilled the prism toe (808) with breakouts indicating SHmax parallel to the convergence vector, in contrast to Exp. 314 results. The stress state in the shallow prism at Site 808 may be affected by nearby seamount subduction or may represent differences in strain partitioning. On the Cascadia margin, two drilling legs have collected LWD borehole images (Leg 204 and Exp. 311). Leg 204 drilled 3 sites at hydrate ridge in the C Cascadia outer prism with breakout orientations variable between closely spaced sites. Prism fold axes are parallel to the margin so we might expect SHmax perpendicular to the margin as in Exp. 314. Deviations from this orientation may reflect local and surface effects (Goldberg and Janik, 2006). Exp. 311, N Cascadia, drilled 5 sites across the prism with breakouts in LWD images. Subduction is not oblique here, in contrast to the other sites discussed, and most sites indicate SHmax almost parallel to convergence and normal to major fold axes. In one case, the in situ stress orientation is also compatible with shallow normal faulting from seismic data. Site 1325, in a slope basin, deviates from this orientation and may reflect local processes. Borehole breakouts within the shallow forearc of convergent margins are often in agreement with other indications of regional tectonic stress and may be indicative of processes at depth. Deviations may represent local stresses due to gravitational processes.

Disentangling synergistic climate drivers on the evolution of two species of planktonic foraminifera on regional and global scales

NASA Astrophysics Data System (ADS)

Brombacher, A.; Wilson, P. A.; Bailey, I.; Ezard, T. H. G.

2016-02-01

Evolution is driven by a combination of biotic and abiotic factors. When quantifying the effects of abiotic drivers, evolutionary change is generally described as a response to a single environmental parameter assumed to represent global climate. However, climate is a complex system of many interacting factors and characterized by high regional variability. Therefore, to understand the role of climate in evolutionary change, we need to consider multiple environmental parameters, across local, regional and global scales, as well as their interactions. The deep-sea microfossil record is sufficiently complete that sufficiently continuous multivariate climatic and multivariate trait data can be obtained from the same samples. Here we present morphological records of the planktonic foraminifera species Globoconella puncticulata and Truncorotalia crassaformis over a 500,000-year interval directly preceding the extinction of G. puncticulata (2.41 Ma). Material was collected from five North Atlantic sites (ODP Sites 659 [18° N], 925 [3° N] and 981 [55° N], IODP Site U1313 [41° N] and DSDP Site 606 [37° N]). Test size and shape of over 35,000 individuals were measured and compared to site-specific records of sea surface temperature, primary productivity and marine aeolian dust deposition, as well as to global records of ice volume, ocean circulation and atmospheric CO2, and all two-way interactions. Morphological parameters respond weakly to individual climate parameters. Once interactions among all studied climate parameters were incorporated, abiotic change explained around 35% of the evolutionary variance. Observed covariances between environmental parameters vary strongly with glacial-interglacial cyclicity, implying that the relationships among climate variables and their relative influences on evolutionary change varied through time. This time dependence cautions against unfettered use of dimension reduction techniques, such as principal components analysis, to extract a single, supposedly dominant, proxy. Furthermore species' responses differed between geographic locations, impressing the need to test how interactions among multiple climate variables at different regional settings shape the biotic microevolutionary response to local and global abiotic change.

MANUAL FOR OPERATIONAL DOCUMENTARY PHOTOGRAPHY (ODP)

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

Hendrix, V.V.

1963-12-23

The SL-1 incident showed the need for pre-incident photographs of the facility to aid in rescue or recovery operations. A system of documentary photographic coverage was developed to fill this need for all the NRTS reactors and facilities. In this system, aperture cards with photographic negatives are used, and the cards are coded with respect to facility, room, floor, angle, and other variables. Operational planning for documentary photographs and updating of the cards are discussed. (D.L.C.)

MDA-based EHR application security services.

PubMed

Blobel, Bernd; Pharow, Peter

2004-01-01

Component-oriented, distributed, virtual EHR systems have to meet enhanced security and privacy requirements. In the context of advanced architectural paradigms such as component-orientation, model-driven, and knowledge-based, standardised security services needed have to be specified and implemented in an integrated way following the same paradigm. This concerns the deployment of formal models, meta-languages, reference models such as the ISO RM-ODP, and development as well as implementation tools. International projects' results presented proceed on that streamline.

Eastern Asian Emissions of Anthropogenic Halocarbons Deduced from Aircraft Concentration Data

NASA Technical Reports Server (NTRS)

Palmer, Paul I.; Jacob, Daniel J.; Mickle, Loretta, J.; Blake, Donald R.; Sachse, Glen W.; Fuelberg, Henry E.; Kiley, Christopher M.

2003-01-01

The Montreal Protocol restricts production of ozone-depleting halocarbons worldwide. Enforcement of the protocol has relied mainly on annual government statistics of production and consumption of these compounds (bottom-up approach). We show here that aircraft observations of ha1ocarbon:CO enhancement ratios on regional to continental scales can be used to infer halocarbon emissions, providing independent verification of the bottom-up approach. We apply this topdown approach to aircraft observations of Asian outflow &om the TRACE-P mission over the western Pacific (March-April 2001) and derive emissions from eastern Asia (China, Japan, and Korea). We derive an eastern Asian carbon tetrachloride (CCl4) source of 21.5 Gg yr(sup -1), several-fold larger than previous estimates and amounting to -30% of the global budget for this gas. Our emission estimate for CFC-11 from eastern Asia is 50% higher than inventories derived from manufacturing records. Our emission estimates for methyl chloroform (CH3CC13) and CFC-12 are in agreement with existing inventories. For halon 1211 we find only a strong local source originating from the Shanghai area. Our emission estimates for the above gases result in a approximately equal to 40% increase in the ozone depletion potential (ODP) of Asian emissions relative to previous estimates, corresponding to a approximately equal to 10% global increase in ODP.

Understanding Science and Technology Interactions Through Ocean Science Exploration: A Summer Course for Science Teachers

NASA Astrophysics Data System (ADS)

Baldauf, J.; Denton, J.

2003-12-01

In order to replenish the national supply of science and mathematics educators, the National Science Foundation has supported the formation of the Center for Applications of Information Technology in the Teaching and Learning of Science (ITS) at Texas A&M University. The center staff and affiliated faculty work to change in fundamental ways the culture and relationships among scientists, educational researchers, and teachers. ITS is a partnership among the colleges of education, science, geosciences, agriculture and life science at Texas A&M University. Participants (teachers and graduate students) investigate how science is done and how science is taught and learned; how that learning is assessed, and how scholarly networks among all engaged in this work can be encouraged. While the center can offer graduate degrees most students apply as non-degree seekers. ITS participants are schooled on classroom technology applications, experience working on project teams, and access very current research work being conducted by scientists. ITS offers a certificate program consisting of two summer sessions over two years that results in 12 hours of graduate credit that can be applied to a degree. Interdisciplinary project teams spend three intense weeks connecting current research to classroom practices. During the past summer with the beginning of the two-year sequence, a course was implemented that introduced secondary teachers to Ocean Drilling Program (ODP) contributions to major earth science themes, using core and logging data, engineering (technology) tools and processes. Information Technology classroom applications were enhanced through hands-on laboratory exercises, web resources and online databases. The course was structured around the following objectives. 1. Distinguish the purpose and goals of the Ocean Drilling Program from the Integrated Ocean Drilling Program and describe the comparable science themes (ocean circulation, marine sedimentation, climate history, sea level change and geological time). This objective will be achieved by correctly answering 8 of 10 multiple choice items on course posttest on science themes of ODP/IODP. 2. Describe the technical tools and processes for determining sea level history by preparing and presenting a multimedia presentation on coring. 3. Describe the processes for describing a drill core and apply those processes to core samples from Leg 194 by developing a laboratory analysis report on core samples based on protocol for analyzing cores. 4. Explain the distinguishing features of scientific from industrial coring processes by developing a paper that contrasts scientific from industrial coring processes. 5. Describe the substructure of the ocean basin and the scientific tools (equipment and processes) used to explore this substructure by preparing and presenting a multimedia presentation on bore hole data interpretation. 6. Analyze and interpret data sets from a bore hole by developing a laboratory analysis report on bore-hole data. Student performance data for objectives indicate a 16% average positive change on the science themes addressed in instruction related to objective one occurred. Similarly, a 12% average positive change occurred on science education topics related to earth science among the students in this class. Ongoing contact between faculty members during the academic year is planned as these summer participants engage in implementing IT interventions and professional development experiences based on ocean science data experienced in the summer experience.

Unraveling multiple phases of sulfur cycling during the alteration of ancient ultramafic oceanic lithosphere

NASA Astrophysics Data System (ADS)

Schwarzenbach, Esther M.; Gill, Benjamin C.; Johnston, David T.

2018-02-01

Ultramafic-hosted hydrothermal systems - characterized by ongoing serpentinization reactions - exert an important influence on the global sulfur cycle. Extensive water-rock interaction causes elemental exchange between seawater and the oceanic lithosphere, effectively removing sulfate from seawater through both abiogenic and biogenic processes. Here, we use bulk rock multiple sulfur isotope signatures (32S, 33S, 34S) and in situ sulfide analyses together with petrographic observations to track the sulfur cycling processes and the hydrothermal evolution of ancient peridotite-hosted hydrothermal systems. We investigate serpentinized peridotites from the Northern Apennine ophiolite in Italy and the Santa Elena ophiolite in Costa Rica and compare those with the Iberian Margin (Ocean Drilling Program (ODP) Leg 149 and 173) and the 15°20‧N Fracture Zone along the Mid-Atlantic Ridge (ODP Leg 209). In situ measurements of sulfides in the Northern Apennine serpentinites preserve a large range in δ34Ssulfide of -33.8 to +13.3‰ with significant heterogeneities within single sulfide grains and depending on mineralogy. Detailed mineralogical investigation and comparison with bulk rock Δ33Ssulfide and in situ δ34Ssulfide data implies a thermal evolution of the system from high temperatures (∼350 °C) that allowed thermochemical sulfate reduction and input of hydrothermal sulfide to lower temperatures (<120 °C) that permitted microbial activity. The change in temperature regime is locally preserved in individual samples and correlates with the progressive uplift and exposure of mantle rock associated with detachment faulting along a mid-ocean ridge spreading center. The Santa Elena peridotites preserve distinct signatures for fluid circulation at high temperatures with both closed system thermochemical sulfate reduction and input of mafic-derived sulfur. In addition, the peridotites provide strong evidence that low Ca2+ concentrations in peridotite-hosted systems can limit sulfate removal during anhydrite precipitation at temperatures above 150 °C. This may play a central role for the availability of sulfate to microbial communities within these systems. Overall, the combined application of in situ and bulk rock multiple sulfur isotope measurements with petrographic observations allows us to resolve the different episodes of sulfur cycling during alteration of the oceanic lithosphere and the temporal changes between abiogenic and biogenic processes that control the sulfur cycling in these systems.

Magnetic Properties and Absolute Paleointensity of Upper Oceanic Crust Generated by Superfast Seafloor Spreading, ODP Leg 209.

NASA Astrophysics Data System (ADS)

Herrero-Bervera, E.; Acton, G.

2005-12-01

We investigate the magnetic mineralogy and absolute paleointensity of oceanic basalt samples from Hole 1256D, cored during Ocean Drilling Program (ODP) Leg 206. Hole 1256D is located on the Cocos Plate about 5 km east of the transition zone between marine magnetic anomalies 5Bn.2n and 5Br (~15 Ma). During Leg 206, the hole penetrated 502 m into basalts of the upper oceanic crust that was generated by superfast seafloor spreading (>200 mm/yr) along the East Pacific Rise. Rock magnetic investigations included continuous low field (k-T) thermomagnetic analyses, alternating field (AF) and thermal demagnetization, optical microscopy, saturation isothermal remanent magnetization (SIRM), and magnetic grain size analyses. Following the removal of a drilling overprint, AF and thermal demagnetization paths for most samples decay linearly to the origin on orthogonal vector end point diagrams, suggesting that a stable characteristic remanent magnetization component can be resolved. Optical microscopy and k-T (Curie points) identified titanomagnetites and titanomaghemites as the main magnetic carriers and grain size studies indicate that the carriers are either single domain (SD) and/or pseudosingle domain (PSD) in nature. Using the modified Thellier-Coe double heating method, we determined absolute paleointensity determinations for 51 specimens sampled from different ``stratigraphic'' levels of the core. pTRM checks were performed systematically one temperature step down the last pTRM acquisition in order to document magnetomineralogical changes during heating. The temperature was incremented by steps of 50°C between room temperature and 500°C and every 25-30°C for higher temperatures. The paleointensity determinations were obtained from the slope of the Arai diagrams. Special care was taken to interpret the Arai diagrams within the same range of temperatures lower than 300°C unless a clear and unique slope was present over a higher range of temperatures. Only about 10 percent of the samples yielded acceptable results. The paleofield estimated from these samples ranges between 28 to 16 micro Teslas (i.e., VADM of 6 to 4 x 1022 A/m2), which is concordant with the average paleofield intensity for the period between 0-160 Myr (4 ± 2 x1022 A/m2) and half of the strength of the present field (~8x1022 A/m2).

Modeling Water Balance of Dammed Lakes Using Computer Code Matlab-Simulink/ Modelowanie Bilansu Wodnego Piętrzonych Jezior Za Pomocą Programu Komputerowego Matlab-Simulink

NASA Astrophysics Data System (ADS)

Błażejewski, Ryszard; Murat-Błażejewska, Sadżide; Jędrkowiak, Martyna

2014-09-01

The paper presents a water balance of a flow-through, dammed lake, consisted of the following terms: surface inflow, underground inflow/outflow based on the Dupuit's equation, precipitation on the lake surface, evaporation from water surface and outflow from the lake at which a damming weir is located. The balance equation was implemented Matlab-Simulink®. Applicability of the model was assessed on the example of the Sławianowskie Lake of surface area 276 ha and mean depth - 6.6 m, Water balances, performed for month time intervals in the hydrological year 2009, showed good agreement for the first three months only. It is concluded that the balancing time interval should be shorter (1 day) to minimize the errors. For calibration purposes, measurements of ground water levels in the vicinity of the lake are also recommended. Praca przedstawia bilans wodny przepływowego piętrzonego jeziora, uwzględniający dopływ powierzchniowy, dopływ i odpływ podziemny opisany równaniem Dupuita, opad na powierzchnię jeziora, parowanie z powierzchni wody oraz odpływ w przekroju zamkniętym jazem piętrzącym. Z uwagi na nieliniowe związki wymienionych składników bilansu z poziomem wody w jeziorze, do obliczeń wykorzystano program komuterowy Matlab-Simulink®. Przydatność modelu sprawdzono na przykładzie Jeziora Sławianowskiego o powierzchni 276 ha i średniej głębokości - 6,6 m. Jezioro to zostało podzielone na dwa akweny o zróżnicowanej głębokości. Wyniki obliczeń miesięcznych bilansów wodnych dla roku hydrologicznego 2009, wykazały dobrą zgodność z pomiarami jedynie dla trzech pierwszych miesięcy. Stwierdzono, że dla zmniejszenia błędów obliczeniowych należałoby skrócić interwał bilansowania do jednej doby. Kalibracja modelu byłaby łatwiejsza i bardziej adekwatna, gdyby do oszacowania przewodności hydraulicznej przyległych do jeziora gruntów i osadów dennych wykorzystać badania poziomów wody w piezometrach, zlokalizowanych w kilku transektach, prostopadłych do linii brzegowej jeziora.

Changes in biogenic and detrital fluxes across the last two glacial terminations at the Shatsky Rise

NASA Astrophysics Data System (ADS)

Bradtmiller, L. I.; Kinsley, C. W.; McGee, D.; Ford, H. L.; Perala-Dewey, J.; Zhang, Y.

2017-12-01

The Shatsky Rise is located within strong gradients in SST and biological productivity between the subtropical and subarctic Pacific gyres. The region is highly sensitive to changes in atmospheric and oceanic circulation on glacial-interglacial timescales, which affect the delivery of Fe-bearing dust and other major nutrients, respectively. Here we use a range of proxies in an attempt to determine the effects of changes in westerly winds and gyre boundaries on dust delivery and biological productivity. We present 230Th-normalized fluxes of opal, Corg, CaCO3, and detrital material at ODP Site 1208 over the last two glacial terminations, extending to 145ka. Opal, Corg, and carbonate are products of surface biological productivity, while most detrital material at this site arrives in the form of windborne East Asian dust. In addition, we calculate the concentration of authigenic U as an indicator of relative oxygenation of the sediment water interface. We observe elevated opal and dust fluxes during the last two glacial maxima, and a decrease in both components during deglaciations. Authigenic U shows distinct peaks at the onset of both terminations. The peak at the penultimate deglaciation is also associated with a large peak in opal flux, while the peak in authigenic U during the last termination does not appear to be associated with any large changes in biogenic fluxes. We compare our records with other data from the subtropical-subarctic transition zone, and suggest that our data are consistent with northward shift of the mean position of the westerly jet and subarctic front during deglaciations.

Pliocene Warm Period Upwelling in the Southern Benguela Region

NASA Astrophysics Data System (ADS)

Petrick, B. F.; McClymont, E.; Felder, S.; Leng, M. J.; Rosell Mele, A.; Rueda, G.

2014-12-01

The mid-Pliocene has been proposed as a possible analogue for understanding future climate change and testing climate models. Previous work has shown that during the Pliocene the major upwelling systems were relatively warm, and thus either inactive, contracted, or upwelling warmer waters than present. Here we examine evidence from a core site located on the margins of the modern Benguela upwelling system, to test whether the upwelling cells had migrated or contracted relative to present during the Pliocene. We applied several organic geochemistry proxies and foraminiferal analyses to reconstruct the Pliocene history of ODP site 1087 (31º28'S, 15º19'E, 1374m water depth), including the UK37' index and TEX86 index (for reconstructing sea surface temperatures), chlorins (for estimating primary productivity) and planktonic foraminifera assemblages (for inferring water mass changes). These proxies show that between 3.5 and 3.0 Ma the southern Benguela region was significantly cooler than the northern Benguela region, the latter where the main upwelling cells are found today. Coupled with higher primary production, a shift in planktonic foraminifera assemblage, and an offset between the UK37' index and TEX86 index, we infer that more extensive upwelling was present in the southern Benguela region during the Pliocene. We infer that the main Benguela upwelling cells had shifted southward relative to today, as a result of changes in the local wind field. We find evidence for pronounced cooling and a shift in the planktonic foraminifera assemblage during the M2 and KM2 glacial stages, showing a sensitivity of Benguela upwelling to these short-lived climate events.

Towards a Framework for Modeling Space Systems Architectures

NASA Technical Reports Server (NTRS)

Shames, Peter; Skipper, Joseph

2006-01-01

Topics covered include: 1) Statement of the problem: a) Space system architecture is complex; b) Existing terrestrial approaches must be adapted for space; c) Need a common architecture methodology and information model; d) Need appropriate set of viewpoints. 2) Requirements on a space systems model. 3) Model Based Engineering and Design (MBED) project: a) Evaluated different methods; b) Adapted and utilized RASDS & RM-ODP; c) Identified useful set of viewpoints; d) Did actual model exchanges among selected subset of tools. 4) Lessons learned & future vision.

Depositional history, nannofossil biostratigraphy, and correlation of Argo Abyssal Plain Sites 765 and 261

USGS Publications Warehouse

Dumoulin, Julie A.; Bown, Paul R.; Stewart, Sondra K.; Kennett, Diana; Mazzullo, Elsa K.

1992-01-01

Sediments from the Argo Abyssal Plain (AAP), northwest of Australia, are the oldest known from the Indian Ocean and were recovered from ODP Site 765 and DSDP Site 261. New biostratigraphic and sedimentologic data from these sites, as well as reinterpretations of earlier findings, indicate that basal sediments at both localities are of Late Jurassic age and delineate a history of starved sedimentation punctuated by periodic influx of calcareous pelagic turbidites.Biostratigraphy and correlation of Upper Jurassic-Lower Cretaceous sediments is based largely on calcareous nannofossils. Both sites yielded variably preserved nannofossil successions ranging from Tithonian to Hauterivian at Site 765 and Kimmeridgian to Hauterivian at Site 261. The nannofloras are comparable to those present in the European and Atlantic Boreal and Tethyan areas, but display important differences that reflect biogeographic differentiation. The Argo region is thought to have occupied a position at the southern limit of the Tethyan nannofloral realm, thus yielding both Tethyan and Austral biogeographic features.Sedimentary successions at the two sites are grossly similar, and differences largely reflect Site 765 's greater proximity to the continental margin. Jurassic sediments were deposited at rates of about 2 m/m.y. near the carbonate compensation depth (CCD) and contain winnowed concentrations of inoceramid prisms and nannofossils, redeposited layers rich in calcispheres and calcisphere debris, manganese nodules, and volcanic detritus. Lower Cretaceous and all younger sediments accumulated below the CCD at rates that were highest (about 20 m/m.y.) during mid-Cretaceous and Neogene time. Background sediment in this interval is noncalcareous claystone; turbidites dominate the sequence and are thicker and coarser grained at Site 765.AAP turbidites consist mostly of calcareous and siliceous biogenic components and volcanogenic smectite clay; they were derived from relatively deep parts of the continental margin that lay below the photic zone, but above the CCD. The Jurassic-Lower Cretaceous section is about the same thickness across the AAP; turbidites in this interval appear to have had multiple sources along the Australian margin. The Upper Cretaceous-Cenozoic section, however, is three times thicker at Site 765 than at Site 261; turbidites in this interval were derived predominantly from the south.Patterns of sedimentation across the AAP have been influenced by shifts in sea level, the CCD, and configuration of the continental margin. Major pulses of calcareous turbidite deposition occurred during Valanginian, Aptian, and Neogene time—all periods of eustatic lowstands and depressed CCD levels. Sediment redeposited on the AAP has come largely from the Australian outer shelf, continental slope, or rise, rather than the continent itself. Most terrigenous detritus was trapped in epicontinental basins that have flanked northwestern Australia since the early Mesozoic.

Calcareous nannofossil evidence for Marine Isotope Stage 31 (1 Ma) in the AND-1B Core, ANDRILL McMurdo Ice Shelf Project (Antarctica).

NASA Astrophysics Data System (ADS)

Villa, G.; Persico, D.; Wise, S. W.; Gadaleta, A.

2009-04-01

During the austral summer 2006 the ANDRILL Program recovered a 1285 m-long succession of cyclic glacimarine sediments from the McMurdo Ice Shelf (MIS). The aim of the MIS Project was to obtain continuous Neogene (c. 0-10 Ma) glacial, glacimarine, volcanic, and biogenic sediments that have accumulated in the region of the McMurdo Ice Shelf (Ross Sea) nourished by ice flowing from East Antarctic Ice Sheet (EAIS) outlet glaciers in the Transantarctic Mountains (TAM). The MIS AND-1B drill core represents the longest and most complete (98% recovery) geological record from the Antarctic continental margin to date, and will provide a key reference record of climate and ice-sheet variability through the Late Neogene; detailed investigations of this record will contribute for improving our knowledge of Antarctica's influence on global climate. Preliminary on-ice analysis of the smear slides of the Andrill core revealed calcareous microfossils (dinoflagellates, calciosponge spicula and small foraminifera) occurring with variable concentrations. The presence of thoracosphaerid fragments in the smear slides of the first 600 mbsf (Quaternary), probably belong to the species Thoracosphaera saxea (Stradner 1961), and Thoracosphaera heimi (Kamptner, 1941) and other, potentially undescribed species (Villa & Wise 1998), suggests either a peculiar adaptation to this environment, due to their ability to develop cysts or warmer conditions at the time of their deposition, or a combination of both. However, they represent an additional element to use with the other proxies for inferring palaeoenvironmental conditions of the core. Subsequent shore-based analyses of 100 samples from 86-96 mbsf revealed for the first time the presence of Pleistocene coccolithophorids at these high southern latitudes (77° S), including: Coccolithus pelagicus, small Gephyrocapsa, Reticulofenestra asanoi, Pseudoemiliania lacunosa, Dictyoccocites productus, Reticulofenestra sp., Reticulofenestra minutula, Thoracosphaera spp.. The presence of several Tertiary reworked species and rare Cretaceous reworked taxa are interpreted in terms of provenance. As the lower temperature limit for living calcareous nannoplankton is about 2.5°C, the presence of nannofossils from 86 to 96 mbsf, though rare, is an indication of ice-free and sea surface temperatures warmer than today, in the Ross Sea. The presence of numerous volcaniclastic units and biosiliceous sediments from 86.6 to 92.5 mbsf indicate an extended period of open-water conditions with no sea ice, beyond the calving line. An 40Ar/39Ar age of 1.014 ± 0.004 Ma on pumice at 85.50 mbsf confirms the age assignment given by diatom biostratigraphy (1.07 Ma) for this interval. Accordingly, the short normal magnetozone between 84.97 and 91.13 mbsf is correlated with the Jaramillo Subchron (C1r.1n) (Wilson et al., 2007). The presence of nannofossil in the biogenic interglacial sediments is consistent with warm episode of surface waters and open marine conditions during the Jaramillo subchron, at ~1 Ma, which corresponds with Marine isotope stage (MIS-31) (Naish et al., 2007). The "superinterglacial" associated with MIS 31 was the last significant warm interglacial of the obliquity-dominated world, and may represent a precursor to the high-amplitude eccentricity-dominated cycles that followed the mid-Pleistocene climate shift. Climate proxies from other studies from the Southern Ocean at ODP Site 1165 (Villa et al., 2008), at ODP Site 1094 (Scherer et al., 2008), and from the Antarctic margin in a shelly carbonate sequence at Cape Roberts 1 (Villa and Wise, 1998; Scherer et al., 2008) also support the idea of a warming event during this time, suggesting that it was extended around the Antarctic Continent. This in turn implies a total or partial collapse of McMurdo Ice Shelf and a concurrent shift or temporary dissipation of the Polar Front (Antarctic Convergence) and Antarctic Divergence that currently serve as barriers to the influx of calcareous nannofossils to the margins of Antarctica. The warm interval during the Jaramillo Subchron shows that these areas were more climatically dynamic than previously thought and calls into questions the notion that the EAIS has remained in a stable polar condition since the late Neogene. The warm surface water event reported here is especially significant given its proximal position to the Antarctic ice sheet. References Naish, T., Powell, R., Levy R., Henrys S., Krissek L., Niessen F., Pompilio M., Scherer R., Wilson G. & the ANDRIL-MIS Science Team, 2007. - Synthesis of the Initial Scientific Results of the MIS Project (AND-1B Core), Victoria Land Basin, antartica. Terra Antartica, 14(3), 317-327. Scherer, R., Bohaty, S., Dunbar, R.B., Esper, O., Flores, J.A., Gersonde, R., Harwood, D.M., Roberts, A.P., Taviani, M., 2008. Antarctic records of precession-paced insolation-driven warming during early Pleistocene Marine Isotope Stage 31. Geophys. Res. Lett., vol. 35, L03505, doi: 10.1029/2007GL032254. Villa G. and Wise S.W., 1998 - Quaternary calcareous nannofossils from the Antarctic region. Terra Antartica, 5(3), 479-484. Villa G., Lupi, C., Cobianchi, M., Florindo, F., Pekar, S.F., 2008. A Pleistocene warming event at 1 Ma in Prydz Bay, East Antarctica: evidence from ODP Site 1165. Palaeogeography, Palaoeclimatology, Palaeoecology, doi:10.1016/J.palaeo.2007.08.017. Wilson G., Levy R., Browne G., Dunbar, N., Florindo F., Henrys S., Graham I., McIntosh W., McKay R., Naish T., Ohneiser C., Powell R., Ross J., Sagnotti L., Scherer R., Sjunneskog C., Strong C.P. Taviani M., Winter D., & the ANDRILL MIS-Science Team, 2007. Preliminary Integrated Chronostratigraphy of AND-1B Drill Core, ANDRILL McMurdo Ice Shelf Project, Antarctica. Terra Antartica 14 (3), 297-316.

Constraining Sources of Subducted and Recycled Carbon Along the Sunda Arc

NASA Astrophysics Data System (ADS)

House, B. M.; Bebout, G. E.; Hilton, D. R.; Rodriguez, B.; Plank, T. A.

2014-12-01

From sediment subduction rates and C contents at ODP/DSDP sites 765 and 211, we estimate the rate of C subduction along ~2000 km of the East Sunda Arc to be ~0.4 Tg C yr-1, representing a significant source of subducted volatiles [1]. However volatile recycling efficiency and the provenance of recycled volatiles in this region remain poorly understood. With new δ13C measurements of both carbonate and organic carbon from sites 211 and 765, we present the most detailed study yet of the spatial variability of subducted C and recycled CO2 provenance along the strike of the arc. Furthermore we demonstrate the importance of oceanic crustal carbonate as a C source in a subduction zone that is otherwise carbonate starved. Carbonate content throughout the sediment column decreases dramatically between site 765, approximately 250 km from the Australian continental margin, and site 211, approximately 300 km southwest of the trench and outboard of the Sunda Strait between Sumatra and Java. Continental and shelf carbonate input from the Australian margin dominates shallow deposits at site 765, but underlying pelagic sediments are thought to contribute the majority of inorganic C to the arc. The paucity of carbonate in sediments at site 211 suggests that along this segment essentially all carbonate subducted is derived from altered ocean crust, presenting an opportunity to study the effects of crustal carbonate input. While previous C provenance studies relied on globally-averaged δ13C values for organic and inorganic C in subducted sediments, we present new estimates based on measured δ13CVPDB of carbonate (average of ~2‰ in subducted sediments) and organic carbon (-22.5 to -23‰ average) along with previously published efflux data [2]. These estimates suggest that the arc-averaged ratio of carbonate to organic C subducted along the East Sunda Arc is nearly identical to the inorganic to organic C ratio represented in volcanic and hydrothermal CO2 output, suggesting that differential devolatilization of carbonate and organic C is limited. Our calculated CO2 recycling efficiency of 10 to 20% - which does not include fore-arc outgassing - agrees with geochemical models predicting up to 80% of subducted C may be carried into the deep mantle [3]. [1] Hilton et al., 2002; [2] Halldórsson et al., 2013; [3] Cook-Kollars et al., 2014

Deglacial dust provenance changes in the Eastern Equatorial Pacific and implications for ITCZ movement

NASA Astrophysics Data System (ADS)

Xie, Ruifang C.; Marcantonio, Franco

2012-02-01

The provenance of eolian dust supplied to deep-sea sediments has the potential to offer insights into changes in past atmospheric circulation. Specifically, measuring temporal changes in dust provenance can shed light on changes in the mean position of the Intertropical Convergence Zone (ITCZ), a region acting as a barrier separating wind-blown material derived from northern versus southern hemisphere sources. Here we have analyzed Nd, Sr, and Pb isotope ratios in the operationally-defined detrital component extracted from deep-sea sediments in the eastern equatorial Pacific (EEP) along a meridional transect at 110°W from 3°S to 7°N (ODP Leg 138, sites 848-853). Sr isotope results show that barite Sr has a significant influence on 87Sr/86Sr isotope ratios of samples in the upwelling zone of the EEP. However, sites located >3° or more away from the equator (sites 852 and 853) are believed to not be affected by barite Sr and provide useful detrital Sr signals. 208Pb/206Pb and 207Pb/206Pb ratios in all cores fall into the Pb-isotope space of five potential dust sources (Asia, North and Central/South America, Sahara, and Australia), with no distinct isotopic fingerprinting of the dominant source(s). ɛNd values were most valuable for discerning detrital source provenance, and their values at all sites, ranging from -5.46 to -3.25, were more unradiogenic for sediments deposited during the last glacial than for those deposited during the Holocene. There are distinct latitudinal trends in the ɛNd values, with more radiogenic values further south and less radiogenic values further north, excluding site 848. This distinction holds true for both Holocene and last glacial periods. For the most southerly site, 848, we invoke, for the first time, a distinct southern hemisphere Australian source as being responsible for the unradiogenic Nd isotope ratios. Both average last glacial and Holocene ɛNd values show similar sharp gradients along the transect between 5.29°N and 2.77°N, suggesting little movement of the glacial ITCZ in the EEP. However, during the deglacial, this gradient is stronger and shifted further north between 5.29°N and 7.21°N, suggesting a more northerly, possibly stronger, deglacial ITCZ.

A major change in North Atlantic deep water circulation 1.6 million years ago

NASA Astrophysics Data System (ADS)

Khélifi, N.; Frank, M.

2014-07-01

The global ocean-climate system has been highly sensitive to the formation and advection of deep overflow water from the Nordic Seas as integral part of the Atlantic Meridional Overturning Circulation (AMOC) but its evolution over the Pliocene-Pleistocene global cooling is not fully understood. In particular, changes in the sources and mixing of prevailing deep waters that were involved in driving overturning throughout the Pliocene-Pleistocene climate transitions are not well constrained. Here we investigate the evolution of a substantial deep southward return overflow of the AMOC over the last 4 million years. We present new records of the bottom-water radiogenic neodymium isotope (ϵNd) variability obtained from three sediment cores (DSDP site 610 and ODP sites 980/981 and 900) at water depths between 2170 and 5050 m in the northeast Atlantic. We find that prior to the onset of major Northern Hemisphere glaciation (NHG) ∼3 million years ago (Ma), ϵNd values primarily oscillated between -9 and -11 at all sites, consistent with enhanced vertical mixing and weak stratification of the water masses during the warmer-than-today Pliocene period. From 2.7 Ma to ∼2.0 Ma, the ϵNd signatures of the water masses gradually became more distinct, which documents a significant advection of Nordic Seas overflow deep water coincident with the intensification of NHG. Most markedly, however, at ∼1.6 Ma the interglacial ϵNd signatures at sites 610 (2420 m water depth (w.d.)) and 980/981 (2170 m w.d.) synchronously and permanently shifted by 2 to 3 ϵNd units to less radiogenic values, respectively. Since then the difference between glacial and interglacial ϵNd values has been similar to the Late Quaternary at each site. A decrease of ∼2ϵNd units at 1.6 Ma was also recorded for the deepest water masses by site 900 (∼5050 m w.d.), which thereafter, however, evolved to more radiogenic values again until the present. This major ϵNd change across the 1.6 Ma transition reflects a significant reorganization of the overturning circulation in the northeast Atlantic paving the way for the more stratified water column with distinct water masses prevailing thereafter.

Deposition of pyromagnetically-enhanced Marlboro Clay offset from spherule peak at onset of CIE and Paleocene-Eocene boundary at the midshelf Millville core site (NJ Coastal Plain)

NASA Astrophysics Data System (ADS)

Kent, D. V.; Lanci, L.; Wang, H.; Wright, J.

2017-12-01

Wilson Lake B and Millville are the two core sites on the NJ Coastal Plain where an impact spherule layer was discovered at the base of the Marlboro Clay, coinciding with the onset of the carbon isotope excursion (CIE) that identifies the Paleocene-Eocene boundary (Schaller+2016 Science). At the more proximal Wilson Lake site ( 35 m paleowater depth, 20 km from the paleoshore), enhanced magnetization of the Marlboro Clay marked by a dramatic increase in concentration of submicron magnetic particles closely coincided with the sharp peak in abundance of the spherules (Kent+2017 EPSL). Discounting magnetotactic bacteria and impact plume condensate as significant sources of the magnetic nanoparticles that dominate the magnetization of the 10 m-thick Marlboro Clay, a pyrogenetic origin was postulated whereby a widespread and intense conflagration over the hinterlands, quite possibly impact-induced, produced magnetic nanoparticles in the heated soils, a process long known from wildfires and laboratory heating experiments. The pyromagnetically-enhanced kaolinite-rich soils would have been swept from the denuded landscape and deposited across the adjoining shelf, perhaps as mudwaves, to become the Marlboro Clay. The Millville site at double the paleowater depth and distance to the paleoshore compared to Wilson Lake (Makarova+2017 Paleoceanography) shows a similar enhancement in magnetization of the Marlboro Clay. However, the increase in magnetization in Millville starts well above ( 50 cm) the spherule peak and the onset of the CIE, which coincide with a sharp drop in what little carbonate content there is in the Marlboro Clay, resulting in a zone barren of foraminifers (Makarova+2017 op. cit.). The offset in deposition might be due to added barren zone or a longer transit of the soil muds to the more distant Millville site but would not be expected if the magnetic nanoparticles were produced in more direct response to the onset of the CIE, as from proliferation of magnetotactic bacteria. The pyromagnetic enhancement of soils and their (re)deposition can be viewed as local manifestations of a major event that triggered various global reverberations. For example, there is no counterpart of the Marlboro Clay in ODP Site 1051 on Blake Nose where a spherule layer was also found at the onset of the CIE (Schaller+2016 op. cit.).

Offshore-onshore correlation of upper Pleistocene strata, New Jersey Coastal Plain to continental shelf and slope

USGS Publications Warehouse

Sheridan, R.E.; Ashley, G.M.; Miller, K.G.; Waldner, J.S.; Hall, D.W.; Uptegrove, J.

2000-01-01

High-resolution seismic reflection profiles (~ 1-5 m resolution), including Geopulse(TM), Uniboom(TM), minisparker, small air gun, and water gun sources, are used to trace the ?? 18O stage 5 portion of the outcropping Cape May Formation across the shelf to the continental slope. The ?? 18O stage 5/6 boundary identified at Ocean Drilling Project (ODP) Site 903 on the continental slope anchors the onshore-offshore seismic correlations. Above the ?? 18O stage 5 sequence, there are distinguishable lowstand systems tracts (LST), transgressive systems tracts (TST) and highstand systems tracts (HST) that correlate with ?? 18O stages 4 through 1. Atlantic Margin Coring Project (AMCOR) holes 6009, 6010, 6011, 6020, and 6021C provide age and paleoenvironmental indicators that agree with these correlations. The sub-arctic paleoenvironmental indicators in sequences of ?? 18O stage 3 agree with the cooler temperatures and lower sea-level highstands of that time. Thicker ?? 18O stage 3 and 4 sequences are preserved in the Paleo-Hudson River incised valley across the shelf. The expanded ice sheets during stage ?? 18O 3 compared to ?? 18O stages 1 and 5 probably increased sediment discharge in the Hudson River drainage system. (C) 2000 Elsevier Science B.V. All rights reserved.