Vertical gradients in species richness and community composition across the twilight zone in the North Pacific Subtropical Gyre.

PubMed

Sommer, Stephanie A; Van Woudenberg, Lauren; Lenz, Petra H; Cepeda, Georgina; Goetze, Erica

2017-11-01

Although metazoan animals in the mesopelagic zone play critical roles in deep pelagic food webs and in the attenuation of carbon in midwaters, the diversity of these assemblages is not fully known. A metabarcoding survey of mesozooplankton diversity across the epipelagic, mesopelagic and upper bathypelagic zones (0-1500 m) in the North Pacific Subtropical Gyre revealed far higher estimates of species richness than expected given prior morphology-based studies in the region (4,024 OTUs, 10-fold increase), despite conservative bioinformatic processing. Operational taxonomic unit (OTU) richness of the full assemblage peaked at lower epipelagic-upper mesopelagic depths (100-300 m), with slight shoaling of maximal richness at night due to diel vertical migration, in contrast to expectations of a deep mesopelagic diversity maximum as reported for several plankton groups in early systematic and zoogeographic studies. Four distinct depth-stratified species assemblages were identified, with faunal transitions occurring at 100 m, 300 m and 500 m. Highest diversity occurred in the smallest zooplankton size fractions (0.2-0.5 mm), which had significantly lower % OTUs classified due to poor representation in reference databases, suggesting a deep reservoir of poorly understood diversity in the smallest metazoan animals. A diverse meroplankton assemblage also was detected (350 OTUs), including larvae of both shallow and deep living benthic species. Our results provide some of the first insights into the hidden diversity present in zooplankton assemblages in midwaters, and a molecular reappraisal of vertical gradients in species richness, depth distributions and community composition for the full zooplankton assemblage across the epipelagic, mesopelagic and upper bathypelagic zones. © 2017 The Authors. Molecular Ecology Published by John Wiley & Sons Ltd.

Geologic setting, sedimentary architecture, and paragenesis of the Mesoproterozoic sediment-hosted Sheep Creek Cu-Co-Ag deposit, Helena embayment, Montana

USGS Publications Warehouse

Graham, Garth; Hitzman, Murray W.; Zieg, Jerry

2012-01-01

The northern margin of the Helena Embayment contains extensive syngenetic to diagenetic massive pyrite horizons that extend over 25 km along the Volcano Valley-Buttress fault zone and extend up to 8 km basinward (south) within the Mesoproterozoic Newland Formation. The Sheep Creek Cu-Co deposit occurs within a structural block along a bend in the fault system, where replacement-style chalcopyrite mineralization is spatially associated mostly with the two stratigraphically lowest massive pyrite zones. These mineralized pyritic horizons are intercalated with debris flows derived from synsedimentary movement along the Volcano Valley-Buttress fault zone. Cominco American Inc. delineated a geologic resource of 4.5 Mt at 2.5% Cu and 0.1% Co in the upper sulfide zone and 4 Mt at 4% Cu within the lower sulfide zone. More recently, Tintina Resources Inc. has delineated an inferred resource of 8.48 Mt at 2.96% Cu, 0.12% Co, and 16.4 g/t Ag in the upper sulfide zone. The more intact upper sulfide zone displays significant thickness variations along strike thought to represent formation in at least three separate subbasins. The largest accumulation of mineralized sulfide in the upper zone occurs as an N-S–trending body that thickens southward from the generally E trending Volcano Valley Fault and probably occupies a paleograben controlled by normal faults in the hanging wall of the Volcano Valley Fault. Early microcrystalline to framboidal pyrite was accompanied by abundant and local barite deposition in the upper and lower sulfide zones, respectively. The sulfide bodies underwent intense (lower sulfide zone) to localized (upper sulfide zone) recrystallization and overprinting by coarser-grained pyrite and minor marcasite that is intergrown with and replaces dolomite. Silicification and paragenetically late chalcopyrite, along with minor tennantite in the upper sulfide zone, replaces fine-grained pyrite, barite, and carbonate. The restriction of chalcopyrite to inferred synsedimentary E- and northerly trending faults and absence of definitive zonation with respect to the Laramide Volcano Valley Fault in the lower sulfide zone suggest a diagenetic age related to basin development for the Sheep Creek Cu-Co-Ag deposit.

Hydrogeology of the surficial aquifer in the vicinity of a former landfill, Naval Submarine Base Kings Bay, Camden County, Georgia

USGS Publications Warehouse

Leeth, David C.

1999-01-01

Neogene and Quaternary sediments constitute the surficial aquifer beneath the study area; in descending order from youngest to oldest these include-the Quaternary undifferentiated surficial sand and Satilla Formation; the Pliocene(?) Cypresshead Formation; and the middle Miocene Coosawhatchie Formation. Beneath the surficial aquifer, the upper Brunswick aquifer consists of part of the lower Miocene Marks Head Formation. The surficial aquifer is divided into three water-bearing zones on the basis of lithologic and geophysical properties of sediments, hydraulic-head differences between zones, and differences in ground-water chemistry. The shallowest zone-the water-table zone-consists of medium to fine sand and clayey sand and is present from land surface to a depth of about 77 feet. Below the water-table zone, the confined upper water-bearing zone consists of medium to very coarse sand and is present from a depth of about 110 to 132 feet. Beneath the upper water-bearing zone, the confined lower water-bearing zone consists of coarse sand and very fine gravel and is present from a depth of about 195 to 237 feet. Hydraulic separation is suggested by differences in water chemistry between the water-table zone and upper water-bearing zone. The sodium chloride type water in the water-table zone differs from the calcium bicarbonate type water in the upper water-bearing zone. Hydraulic separation also is indicated by hydraulic head differences of more than 6.5 feet between the water-table zone and the upper water-bearing zone. Continuous and synoptic water-level measurements in the water-table zone, from October 1995 to April 1997, indicate the presence of a water-table high beneath and adjacent to the former landfill-the surface of which varies about 5 feet with time because of recharge and discharge. Water-level data from clustered wells also suggest that restriction of vertical ground-water flow begins to occur at an altitude of about 5 to 10 feet below sea level (35 to 40 feet below land surface) in the water-table zone because of the increasing clay content of the Cypresshead Formation.

Convectively driven PCR thermal-cycling

DOEpatents

Benett, William J.; Richards, James B.; Milanovich, Fred P.

2003-07-01

A polymerase chain reaction system provides an upper temperature zone and a lower temperature zone in a fluid sample. Channels set up convection cells in the fluid sample and move the fluid sample repeatedly through the upper and lower temperature zone creating thermal cycling.

33 CFR 165.T08-0315 - Safety Zone; Upper Mississippi River, Mile 183.0 to 183.5.

Code of Federal Regulations, 2012 CFR

2012-07-01

... River, Mile 183.0 to 183.5. 165.T08-0315 Section 165.T08-0315 Navigation and Navigable Waters COAST... Guard District § 165.T08-0315 Safety Zone; Upper Mississippi River, Mile 183.0 to 183.5. (a) Location. The following area is a safety zone: All waters of the Upper Mississippi River, mile 183.0 to 183.5...

What electrical measurements can say about changes in fault systems.

PubMed Central

Madden, T R; Mackie, R L

1996-01-01

Earthquake zones in the upper crust are usually more conductive than the surrounding rocks, and electrical geophysical measurements can be used to map these zones. Magnetotelluric (MT) measurements across fault zones that are parallel to the coast and not too far away can also give some important information about the lower crustal zone. This is because the long-period electric currents coming from the ocean gradually leak into the mantle, but the lower crust is usually very resistive and very little leakage takes place. If a lower crustal zone is less resistive it will be a leakage zone, and this can be seen because the MT phase will change as the ocean currents leave the upper crust. The San Andreas Fault is parallel to the ocean boundary and close enough to have a lot of extra ocean currents crossing the zone. The Loma Prieta zone, after the earthquake, showed a lot of ocean electric current leakage, suggesting that the lower crust under the fault zone was much more conductive than normal. It is hard to believe that water, which is responsible for the conductivity, had time to get into the lower crustal zone, so it was probably always there, but not well connected. If this is true, then the poorly connected water would be at a pressure close to the rock pressure, and it may play a role in modifying the fluid pressure in the upper crust fault zone. We also have telluric measurements across the San Andreas Fault near Palmdale from 1979 to 1990, and beginning in 1985 we saw changes in the telluric signals on the fault zone and east of the fault zone compared with the signals west of the fault zone. These measurements were probably seeing a better connection of the lower crust fluids taking place, and this may result in a fluid flow from the lower crust to the upper crust. This could be a factor in changing the strength of the upper crust fault zone. PMID:11607664

77 FR 28255 - Safety Zone; Upper Mississippi River, Mile 183.0 to 183.5

Federal Register 2010, 2011, 2012, 2013, 2014

2012-05-14

...-AA00 Safety Zone; Upper Mississippi River, Mile 183.0 to 183.5 AGENCY: Coast Guard, DHS. ACTION... Upper Mississippi River, from mile 183.0 to mile 183.5, in the vicinity of the Merchants Bridge and... Merchants Bridge in the vicinity of mile 183.0 to 183.5 on the Upper Mississippi River. After initial...

78 FR 46258 - Safety Zone; Upper Mississippi River, Mile 662.8 to 663.9

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-31

...-AA00 Safety Zone; Upper Mississippi River, Mile 662.8 to 663.9 AGENCY: Coast Guard, DHS. ACTION... Upper Mississippi River, from mile 662.8 to 663.9, extending the entire width of the river. This safety... mile 662.8 to 663.9 on the Upper Mississippi River. Anticipated traffic on the river presents safety...

76 FR 36316 - Safety Zone; Upper Mississippi River, Mile 180.0 to 179.0

Federal Register 2010, 2011, 2012, 2013, 2014

2011-06-22

...-AA00 Safety Zone; Upper Mississippi River, Mile 180.0 to 179.0 AGENCY: Coast Guard, DHS. ACTION... Upper Mississippi River, from Mile 180.0 to 179.0, extending the entire width of the river. This safety... combat capabilities between Mile 180.0 and 179.0 on the Upper Mississippi River. This event presents...

Three Skin Zones in the Asian Upper Eyelid Pertaining to the Asian Blepharoplasty.

PubMed

Choi, Yeop; Kang, Hyun Gu; Nam, Yong Seok

2017-06-01

Natural looking double fold is an essential and aesthetically pleasing masterpiece in Asian blepharoplasty. This study aims to emphasize the 3 skin zone concept in the Asian upper blepharoplasty. The authors examined the anterior lamella of each skin zone microscopically by performing 31 double-eyelid surgeries and 11 infrabrow lifts. Characteristics of dermal components, subcutaneous tissue, and outer fascia of OOM (OFOOM) at each skin zone were documented. The authors evaluated the vertical scales of each skin zone in young and aged Asian patients who visited the first author's clinic for the primary or secondary upper blepharoplasty with ×3.5 magnifying surgical loupe. The thickness of OOM had no difference among zones 1, 2, and 3. The skin and subdermal tissue had varying characteristics according to its skin zone. At zone 1, it seemed that only thin skin was on the OOM. The anterior lamella of zone 2 seemed to consist of skin, white fascia (OFOOM) including a venous network, and OOM in a gross field. At zone 3, thick skin, thick subcutaneous fatty layer, and OOM were magnified. The OFOOM of zone 3 was not significantly identified due to a sticky adherence with OOM. At the point of vertical scales of skin zone, good eyelids have lower zone 3 ratio and higher zones 1 and 2 ratio with qualified topographic condition. The authors classified the Asian upper eyelid as with 3 skin zones. Based on its anatomical investigation, the authors can afford anthropometric data and supplemental theory for the creation of aesthetic folds.

The occurrence of the Complexiopollis-Atlantopollis zone (Palynomorphs) in the Eagle Ford Group (Upper Cretaceous) of Texas

USGS Publications Warehouse

Christopher, Raymond A.

1982-01-01

The Lower and lower Upper Cretaceous palynological zones defined in the Atlantic Coastal Plain Province and which occur in the eastern Gulf Coastal Plain Province are characterized by a paucity of marine invertebrate fossils. As a result, correlation of these zones with European and provincial stages, as well as with other microfossil and megafossil zones is tenuous. However, an examination of a complete section of the Eagle Ford Group and adjacent strata in Texas reveals that: 1) the upper part of the Woodbine Formation and the Tarrant Formation of the overlying Eagle Ford Group represent a biostratigraphic interval that is absent in the Atlantic and eastern Gulf Coastal Plain Provinces; 2) the Complexiopollis-Atlantopollis Zone (zone IV of some authors) occurs within the Britton Formation (Eagle Ford Group), and is equivalent to the upper part of the Rotalipora cushmani-greenhornensis Subzone (planktic foraminifers) and possibly to the Sciponoceras gracile Zone (ammonites); 3) the Arcadia Park Formation (Eagle Ford Group) contains a mixed assemblage of palynomorphs that includes guides to both the Complexiopollis-Atlantopollis and the overlying Complexiopollis exigua-Santalacites minor Zones, suggesting that biostratigraphic equivalents of the Arcadia Park Formation are not represented in the Atlantic and eastern Gulf Coastal Plain Provinces; and 4) in the basal part of the Austin Chalk of Texas, only one guide palynomorph to the Complexiopollis-Atlantopollis Zone was recognized, but guides to the Complexiopollis exigua-Santalacites minor Zone are present. The Tuscaloosa Group of the eastern Gulf Coastal Plain appears to be biostratigraphically equivalent to the Complexiopollis-Atlantopollis Zone, and therefore correlative with the middle to upper part of the Britton Formation of the Eagle Ford Group.

Decoupling of stream and vegetation solutes during the late stages of weathering: insights from elemental and Mg isotope trends at the Luquillo Critical Zone Observatory, Puerto Rico

NASA Astrophysics Data System (ADS)

Chapela Lara, M.; Schuessler, J. A.; Buss, H. L.; McDowell, W. H.

2017-12-01

During the evolution of the critical zone, the predominant source of nutrients to the vegetation changes from bedrock weathering to atmospheric inputs and biological recycling. In parallel, the architecture of the critical zone changes with time, promoting a change in water flow regime from near-surface porous flow during early weathering stages to more complex flow regimes modulated by clay-rich regolith during the late stages of weathering. As a consequence of these two concurrent processes, we can expect the predominant sources and pathways of solutes to the streams to also change during critical zone evolution. If this is true, we would observe a decoupling between the solutes used by the vegetation and those that determine the composition of the streams during the late stages of weathering, represented by geomorphically stable tropical settings. To test these hypotheses, we are analyzing the elemental and Mg isotopic composition of regolith and streams at the humid tropical Luquillo Critical Zone Observatory. We aim to trace the relative contributions of the surficial, biologically mediated pathways and the deeper, weathering controlled nutrient pathways. We also investigate the role of lithology on the solute decoupling between the vegetation and the stream, by examining two similar headwater catchments draining two different bedrocks (andesitic volcaniclastic and granitic). Our preliminary elemental and Mg isotope results are consistent with atmospheric inputs in the upper 2 m of regolith in both lithologies and with bedrock weathering at depth. During a short storm event ( 6 h), a headwater stream draining volcaniclastic bedrock showed a large variation in Mg and δ26Mg, correlated with total suspended solids, while another similar headwater granitic stream showed a much narrower variation. A larger stream draining volcaniclastic bedrock showed changes in Mg concentration in response to rain during the same storm event, but did not change in δ26Mg, suggesting the surficial-deep decoupling of solutes we observe in regolith profiles and headwater catchments might be overwhelmed by storage effects at increasing water residence times.

76 FR 77901 - Safety Zone; Upper Mississippi River, Mile 389.4 to 403.1

Federal Register 2010, 2011, 2012, 2013, 2014

2011-12-15

...-AA00 Safety Zone; Upper Mississippi River, Mile 389.4 to 403.1 AGENCY: Coast Guard, DHS. ACTION... Upper Mississippi River, from Mile 389.4 to 403.1, extending the entire width of the river located on... 389.4 to 403.1 on the Upper Mississippi River. Under 5 U.S.C. 553(d)(3), the Coast Guard finds that...

A revision of the Norian Conchostracan Zonation in North America and its implications for Late Triassic North American tectonic history

USGS Publications Warehouse

Weems, Robert E.; Lucas, Spencer G.

2015-01-01

Collections of Upper Triassic (Norian) conchostracans from the upper Cumnock and lower Sanford formations (North Carolina), Bull Run Formation (Virginia), Gettysburg Formation (Pennsylvania), Passaic Formation (New Jersey), Blomidon Formation (Nova Scotia), and Redonda Formation (New Mexico) have significantly expanded our knowledge of the Norian conchostracan faunas in these units. These collections show that the temporal and spatial distribution of Norian conchostracans in North America is more complex and more environmentally controlled than previously thought. The new collections require a revision and simplification of the published conchostracan zonation for this interval. The revised zonation, based almost entirely on evolution within the lineage of the conchostracan genus Shipingia, consists of five zones: the Shipingia weemsi-Euestheria buravasi zone (Lacian), the Shipingia mcdonaldi zone (lower Alaunian), the Shipingia hebaozhaiensis zone (upper Alaunian), the Shipingia olseni zone (lower and middle Sevatian), and the Shipingia gerbachmanni zone (upper Sevatian). A new species of Norian conchostracan, Wannerestheria kozuri, is described from the Groveton Member of the Bull Run Formation (Virginia). Two new members (Plum Run and Fairfield members) are named in the Gettysburg Formation (Gettysburg Basin, Maryland and Pennsylvania). The distribution of upper Carnian and Norian strata in the Fundy, Newark, Gettysburg, and Culpeper basins indicates that there was a significant, previously undetected tectonic reorganization within these basins that occurred around the Carnian-Norian boundary. The presence of an upper Norian-lower Rhaetian unconformity within the Newark Supergroup is reaffirmed. A re-evaluation of the conchostracan record from the Redonda Formation of the Chinle Group in New Mexico indicates that the four conchostracan-bearing lacustrine beds in this unit are part of only a single, consistently recognizable conchostracan zone, which we here designate as the Shipingia gerbachmanni zone.

Meteoric calcite cementation: diagenetic response to relative fall in sea-level and effect on porosity and permeability, Las Negras area, southeastern Spain

NASA Astrophysics Data System (ADS)

Li, Zhaoqi; Goldstein, Robert H.; Franseen, Evan K.

2017-03-01

A dolomitized Upper Miocene carbonate system in southeast Spain contains extensive upper and lower zones of calcite cementation that cut across the stratigraphy. Cement textures including isopachous and circumgranular, which are consistent with phreatic-zone cementation. Cements in the upper cemented zone are non-luminescent, whereas those in the lower cemented zone exhibit multiple bands of luminescent and non-luminescent cements. In the upper cemented zone, isotopic data show two meteoric calcite lines (MCL) with mean δ18O at - 5.1‰ and - 5.8‰ VPDB, whereas no clear MCL is defined in the lower cemented zone where mean δ18O for calcite cement is at - 6.7‰ VPDB. δ13C values in both cement zones are predominantly negative, ranging from - 10 to + 2‰ VPDB, suggestive of carbon from soil gas or decayed organics. Measurements of Tm ice in primary fluid inclusions yield a mode of 0.0 °C in both zones, indicating calcite cementation from fresh water. These two zones define the positions of two different paleo-water tables that formed during a relative sea-level fall and erosional downcutting during the Plio-Pleistocene. The upper cemented zone pre-dated the lower cemented zone on the basis of known relative sea-level history. Meteoric calcite cementation reduced porosity and permeability, but measured values are inconsistent with simple filling of open pore space. Each texture, boundstone, grainstone, packstone, wackestone, produces a different relationship between percent calcite cement and porosity/permeability. Distribution of cements may be predictable on the basis of known sea-level history, and the effect of the cementation can be incorporated into subsurface geomodels by defining surfaces of rock boundaries that separate cemented zones from uncemented zones, and applying texture-specific relationships among cementation, porosity and permeability.

Study on 3-D velocity structure of crust and upper mantle in Sichuan-yunnan region, China

USGS Publications Warehouse

Wang, C.; Mooney, W.D.; Wang, X.; Wu, J.; Lou, H.; Wang, F.

2002-01-01

Based on the first arrival P and S data of 4 625 regional earthquakes recorded at 174 stations dispersed in the Yunnan and Sichuan Provinces, the 3-D velocity structure of crust and upper mantle in the region is determined, incorporating with previous deep geophysical data. In the upper crust, a positive anomaly velocity zone exists in the Sichuan basin, whereas a negative anomaly velocity zone exists in the western Sichuan plateau. The boundary between the positive and negative anomaly zones is the Longmenshan fault zone. The images of lower crust and upper mantle in the Longmenshan fault, Xianshuihe fault, Honghe fault and others appear the characteristic of tectonic boundary, indicating that the faults litely penetrate the Moho discontinuity. The negative velocity anomalies at the depth of 50 km in the Tengchong volcanic area and the Panxi tectonic zone appear to be associated with the temperature and composition variations in the upper mantle. The overall features of the crustal and the upper mantle structures in the Sichuan-Yunnan region are the lower average velocity in both crust and uppermost mantle, the large crustal thickness variations, and the existence of high conductivity layer in the crust or/and upper mantle, and higher geothermal value. All these features are closely related to the collision between the Indian and the Asian plates. The crustal velocity in the Sichuan-Yunnan rhombic block generally shows normal.value or positive anomaly, while the negative anomaly exists in the area along the large strike-slip faults as the block boundary. It is conducive to the crustal block side-pressing out along the faults. In the major seismic zones, the seismicity is relative to the negative anomaly velocity. Most strong earthquakes occurred in the upper-mid crust with positive anomaly or normal velocity, where the negative anomaly zone generally exists below.

Radial Anisotropy in the Mantle Transition Zone and Its Implications

NASA Astrophysics Data System (ADS)

Chang, S. J.; Ferreira, A. M.

2016-12-01

Seismic anisotropy is a useful tool to investigate mantle flow, mantle convection, and the presence of melts in mantle, since it provides information on the direction of mantle flow or the orientation of melts by combining it with laboratory results in mineral physics. Although the uppermost and lowermost mantle with strong anisotropy have been well studied, anisotropic properties of the mantle transition zone is still enigmatic. We use a recent global radially anisotropic model, SGLOBE-rani, to examine the patterns of radial anisotropy in the mantle transition zone. Strong faster SV velocity anomalies are found in the upper transition zone beneath subduction zones in the western Pacific, which decrease with depth, thereby nearly isotropic in the lower transition zone. This may imply that the origin for the anisotropy is the lattice-preferred orientation of wadsleyite, the dominant anisotropic mineral in the upper transition zone. The water content in the upper transition zone may be inferred from radial anisotropy because of the report that anisotropic intensity depends on the water content in wadsleyite.

77 FR 40518 - Swim Events in the Captain of the Port New York Zone; Hudson River, East River, Upper New York...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-07-10

... 1625-AA00 Swim Events in the Captain of the Port New York Zone; Hudson River, East River, Upper New York Bay, Lower New York Bay; New York, NY ACTION: Final rule. SUMMARY: The Coast Guard is establishing seven temporary safety zones for swim events within the Captain of the Port (COTP) New York Zone. These...

Vitrification of waste with conitnuous filling and sequential melting

DOEpatents

Powell, James R.; Reich, Morris

2001-09-04

A method of filling a canister with vitrified waste starting with a waste, such as high-level radioactive waste, that is cooler than its melting point. Waste is added incrementally to a canister forming a column of waste capable of being separated into an upper zone and a lower zone. The minimum height of the column is defined such that the waste in the lower zone can be dried and melted while maintaining the waste in the upper zone below its melting point. The maximum height of the column is such that the upper zone remains porous enough to permit evolved gases from the lower zone to flow through the upper zone and out of the canister. Heat is applied to the waste in the lower zone to first dry then to raise and maintain its temperature to a target temperature above the melting point of the waste. Then the heat is applied to a new lower zone above the melted waste and the process of adding, drying and melting the waste continues upward in the canister until the entire canister is filled and the entire contents are melted and maintained at the target temperature for the desired period. Cooling of the melted waste takes place incrementally from the bottom of the canister to the top, or across the entire canister surface area, forming a vitrified product.

System and method for producing metallic iron

DOEpatents

Bleifuss, Rodney L; Englund, David J; Iwasaki, Iwao; Fosnacht, Donald R; Brandon, Mark M; True, Bradford G

2013-09-17

A hearth furnace for producing metallic iron material has a furnace housing having a drying/preheat zone, a conversion zone, a fusion zone, and optionally a cooling zone, the conversion zone is between the drying/preheat zone and the fusion zone. A moving hearth is positioned within the furnace housing. A hood or separation barrier within at least a portion of the conversion zone, fusion zone or both separates the fusion zone into an upper region and a lower region with the lower region adjacent the hearth and the upper region adjacent the lower region and spaced from the hearth. An injector introduces a gaseous reductant into the lower region adjacent the hearth. A combustion region may be formed above the hood or separation barrier.

Oyster-bioimmured ammonites from the Upper Albian of Annopol, Poland: stratigraphic and palaeobiogeographic implications

NASA Astrophysics Data System (ADS)

Machalski, Marcin; Kennedy, William J.

2013-12-01

Machalski, M. and Kennedy, W.J. 2013. Oyster-bioimmured ammonites from the Upper Albian of Annopol, Poland: stratigraphic and palaeobiogeographic implications. Acta Geologica Polonica, 63 (4), 545-554. Warszawa. Ammonites Mortoniceras (Subschloenbachia) sp. are preserved as attachment scars on the oyster shells from the topmost portion of the Albian succession at Annopol, Poland. These oyster-bioimmured ammonites show a closest affinity to the representatives of Mortoniceras (Subschloenbachia) characteristic of the upper Upper Albian Mortoniceras perinflatum Zone. No ammonites indicative of the uppermost Albian-lowermost Cenomanian Praeschloenbachia briacensis Zone are recorded. Thus, the hiatus at the Albian-Cenomanian boundary at Annopol embraces the latter zone. The presence (and dominance) of Mortoniceras in the upper Upper Albian ammonite assemblage of Annopol suggests that the representatives of this Tethyan genus could migrate into the epicratonic areas of Poland directly from the Tethyan Realm, via the Lwow (Lviv) region.

47 CFR 27.303 - Upper 700 MHz commercial and public safety coordination zone.

Code of Federal Regulations, 2011 CFR

2011-10-01

... safety coordinator. (1) The description must include, at a minimum; (i) The frequency or frequencies on... 47 Telecommunication 2 2011-10-01 2011-10-01 false Upper 700 MHz commercial and public safety... Rules for WCS § 27.303 Upper 700 MHz commercial and public safety coordination zone. (a) General. CMRS...

Upper Albian and Cenomanian (Cretaceous) ammonites from the Debarsu Formation (Yazd Block, Central Iran)

NASA Astrophysics Data System (ADS)

Wilmsen, Markus; Storm, Marisa; Fürsich, Franz Theodor; Majidifard, Mahmoud Reza

2013-12-01

Wilmsen, M., Storm, M., Fürsich, F.T. and Majidifard, M.R. 2013. Upper Albian and Cenomanian (Cretaceous) ammonites from the Debarsu Formation (Yazd Block, Central Iran). Acta Geologica Polonica, 63 (4), 489-513. Warszawa. New ammonite faunas consisting of 13 taxa provide the first reliable biostratigraphic dating of the Debarsu Formation of the Yazd Block, west-central Iran, indicating several levels in the Upper Albian and Lower Cenomanian, while a foraminiferal assemblage places the top of the Formation in the Middle Turonian. Among the identified ammonite taxa, Acompsoceras renevieri (Sharpe, 1857) is recorded from Iran for the first time. The upper part of the lower Upper Albian is proved by the occurrences of mortoniceratines of the Mortoniceras (M.) inflatum Zone in the lowermost part of the Debarsu Formation. For the upper Upper Albian (traditional Stoliczkaia dispar Zone), the M. (Subschloenbachia ) rostratum and M. (S.) perinflatum zones are proved by their index taxa. However, there is no evidence of the terminal Arrhaphoceras (Praeschloenbachia) briacensis Zone. The upper part of the lower Lower Cenomanian Mantelliceras mantelli Zone (M. saxbii Subzone) is proved by M. saxbii and M. cf. mantelli. Below, there is an ammonite- barren interval of ca. 100 m in thickness between M. (S.) perinflatum zonal strata and the M. saxbii Subzone. The upper Lower Cenomanian is documented by the presence of typically M. dixoni zonal ammonites such as Acompsoceras renevieri. Upper Cenomanian and Turonian ammonites have not been found in the upper part of the Debarsu Formation, but micro-biostratigraphic evidence (planktonic foraminifers) from the uppermost part of the formation indicate that the formation ranges into the Turonian. For the development of the major tectonic unconformity at the base of the overlying Haftoman Formation (which yielded Lower Coniacian inoceramids near its base), only 2-3 myr remain, stressing the geodynamic activity of Central Iran during mid-Cretaceous times.

Quartz crystal growth

DOEpatents

Baughman, Richard J.

1992-01-01

A process for growing single crystals from an amorphous substance that can undergo phase transformation to the crystalline state in an appropriate solvent. The process is carried out in an autoclave having a lower dissolution zone and an upper crystallization zone between which a temperature differential (.DELTA.T) is maintained at all times. The apparatus loaded with the substance, solvent, and seed crystals is heated slowly maintaining a very low .DELTA.T between the warmer lower zone and cooler upper zone until the amorphous substance is transformed to the crystalline state in the lower zone. The heating rate is then increased to maintain a large .DELTA.T sufficient to increase material transport between the zones and rapid crystallization. .alpha.-Quartz single crystal can thus be made from fused quartz in caustic solvent by heating to 350.degree. C. stepwise with a .DELTA.T of 0.25.degree.-3.degree. C., increasing the .DELTA.T to about 50.degree. C. after the fused quartz has crystallized, and maintaining these conditions until crystal growth in the upper zone is completed.

Predicting Plant-Accessible Water in the Critical Zone: Mountain Ecosystems in a Mediterranean Climate

NASA Astrophysics Data System (ADS)

Klos, P. Z.; Goulden, M.; Riebe, C. S.; Tague, C.; O'Geen, A. T.; Flinchum, B. A.; Safeeq, M.; Conklin, M. H.; Hart, S. C.; Asefaw Berhe, A.; Hartsough, P. C.; Holbrook, S.; Bales, R. C.

2017-12-01

Enhanced understanding of subsurface water storage, and the below-ground architecture and processes that create it, will advance our ability to predict how the impacts of climate change - including drought, forest mortality, wildland fire, and strained water security - will take form in the decades to come. Previous research has examined the importance of plant-accessible water in soil, but in upland landscapes within Mediterranean climates the soil is often only the upper extent of subsurface water storage. We draw insights from both this previous research and a case study of the Southern Sierra Critical Zone Observatory to: define attributes of subsurface storage, review observed patterns in its distribution, highlight nested methods for its estimation across scales, and showcase the fundamental processes controlling its formation. We observe that forest ecosystems at our sites subsist on lasting plant-accessible stores of subsurface water during the summer dry period and during multi-year droughts. This indicates that trees in these forest ecosystems are rooted deeply in the weathered, highly porous saprolite, which reaches up to 10-20 m beneath the surface. This confirms the importance of large volumes of subsurface water in supporting ecosystem resistance to climate and landscape change across a range of spatiotemporal scales. This research enhances the ability to predict the extent of deep subsurface storage across landscapes; aiding in the advancement of both critical zone science and the management of natural resources emanating from similar mountain ecosystems worldwide.

Upper Maastrichtian ammonite biostratigraphy of the Gulf Coastal Plain (Mississippi Embayment, southern USA)

USGS Publications Warehouse

Larina, Ekaterina; Garb, Matthew P.; Landman, Neil H.; Dastas, Natalie; Thibault, Nicolas; Edwards, Lucy E.; Phillips, George; Rovelli, Remy; Myers, Corinne; Naujokaityte, Jone

2016-01-01

The Cretaceous outcrop belt of the Mississippi Embayment in the Gulf Coastal Plain (GCP) spans the Cretaceous/Paleogene (K/Pg) boundary. A detailed reconstruction of this time interval is critical for understanding the nature of biotic and environmental changes preceding the end-Cretaceous Mass Extinction event and for deciphering the likely extinction mechanism (i.e., bolide impact versus volcanism). Eight sections encompassing the K/Pg succession across the Mississippi Embayment were analyzed using biostratigraphic sampling of ammonites, dinoflagellates, and nannofossils. An upper Maastrichtian ammonite zonation is proposed as follows, from oldest to youngest:Discoscaphites conradi Zone, D. minardi Zone, and D. iris Zone. Our study documents that the ammonite zonation established in the Atlantic Coastal Plain (ACP) extends to the GCP. This zonation is integrated with nannofossil and dinoflagellate biostratigraphy to provide a framework to more accurately determine the age relationships in this region. We demonstrate that ammonites and dinoflagellates are more reliable stratigraphic indicators in this area than nannofossils because age-diagnostic nannofossils are not consistently present within the upper Maastrichtian in the GCP. This biostratigraphic framework has the potential to become a useful tool for correlation of strata both within the GCP and between the GCP, Western Interior, and ACP. The presence of the uppermost Maastrichtian ammonite D. iris, calcareous nannofossil Micula prinsii, and dinoflagellates Palynodinium grallator and Disphaerogena carposphaeropsis suggests that the K/Pg succession in the GCP is nearly complete. Consequently, the GCP is an excellent setting for investigating fine scale temporal changes across the K/Pg boundary and ultimately elucidating the mechanisms causing extinction.

Finite-frequency wave propagation through outer rise fault zones and seismic measurements of upper mantle hydration

USGS Publications Warehouse

Miller, Nathaniel; Lizarralde, Daniel

2016-01-01

Effects of serpentine-filled fault zones on seismic wave propagation in the upper mantle at the outer rise of subduction zones are evaluated using acoustic wave propagation models. Modeled wave speeds depend on azimuth, with slowest speeds in the fault-normal direction. Propagation is fastest along faults, but, for fault widths on the order of the seismic wavelength, apparent wave speeds in this direction depend on frequency. For the 5–12 Hz Pn arrivals used in tomographic studies, joint-parallel wavefronts are slowed by joints. This delay can account for the slowing seen in tomographic images of the outer rise upper mantle. At the Middle America Trench, confining serpentine to fault zones, as opposed to a uniform distribution, reduces estimates of bulk upper mantle hydration from ~3.5 wt % to as low as 0.33 wt % H2O.

Perfusion scintigraphy and patient selection for lung volume reduction surgery.

PubMed

Chandra, Divay; Lipson, David A; Hoffman, Eric A; Hansen-Flaschen, John; Sciurba, Frank C; Decamp, Malcolm M; Reilly, John J; Washko, George R

2010-10-01

It is unclear if lung perfusion can predict response to lung volume reduction surgery (LVRS). To study the role of perfusion scintigraphy in patient selection for LVRS. We performed an intention-to-treat analysis of 1,045 of 1,218 patients enrolled in the National Emphysema Treatment Trial who were non-high risk for LVRS and had complete perfusion scintigraphy results at baseline. The median follow-up was 6.0 years. Patients were classified as having upper or non-upper lobe-predominant emphysema on visual examination of the chest computed tomography and high or low exercise capacity on cardiopulmonary exercise testing at baseline. Low upper zone perfusion was defined as less than 20% of total lung perfusion distributed to the upper third of both lungs as measured on perfusion scintigraphy. Among 284 of 1,045 patients with upper lobe-predominant emphysema and low exercise capacity at baseline, the 202 with low upper zone perfusion had lower mortality with LVRS versus medical management (risk ratio [RR], 0.56; P = 0.008) unlike the remaining 82 with high perfusion where mortality was unchanged (RR, 0.97; P = 0.62). Similarly, among 404 of 1,045 patients with upper lobe-predominant emphysema and high exercise capacity, the 278 with low upper zone perfusion had lower mortality with LVRS (RR, 0.70; P = 0.02) unlike the remaining 126 with high perfusion (RR, 1.05; P = 1.00). Among the 357 patients with non-upper lobe-predominant emphysema (75 with low and 282 with high exercise capacity) there was no improvement in survival with LVRS and measurement of upper zone perfusion did not contribute new prognostic information. Compared with optimal medical management, LVRS reduces mortality in patients with upper lobe-predominant emphysema when there is low rather than high perfusion to the upper lung.

Numerical models of pore pressure and stress changes along basement faults due to wastewater injection: Applications to the 2014 Milan, Kansas Earthquake

USGS Publications Warehouse

Hearn, Elizabeth H.; Koltermann, Christine; Rubinstein, Justin R.

2018-01-01

We have developed groundwater flow models to explore the possible relationship between wastewater injection and the 12 November 2014 Mw 4.8 Milan, Kansas earthquake. We calculate pore pressure increases in the uppermost crust using a suite of models in which hydraulic properties of the Arbuckle Formation and the Milan earthquake fault zone, the Milan earthquake hypocenter depth, and fault zone geometry are varied. Given pre‐earthquake injection volumes and reasonable hydrogeologic properties, significantly increasing pore pressure at the Milan hypocenter requires that most flow occur through a conductive channel (i.e., the lower Arbuckle and the fault zone) rather than a conductive 3‐D volume. For a range of reasonable lower Arbuckle and fault zone hydraulic parameters, the modeled pore pressure increase at the Milan hypocenter exceeds a minimum triggering threshold of 0.01 MPa at the time of the earthquake. Critical factors include injection into the base of the Arbuckle Formation and proximity of the injection point to a narrow fault damage zone or conductive fracture in the pre‐Cambrian basement with a hydraulic diffusivity of about 3–30 m2/s. The maximum pore pressure increase we obtain at the Milan hypocenter before the earthquake is 0.06 MPa. This suggests that the Milan earthquake occurred on a fault segment that was critically stressed prior to significant wastewater injection in the area. Given continued wastewater injection into the upper Arbuckle in the Milan region, assessment of the middle Arbuckle as a hydraulic barrier remains an important research priority.

77 FR 53769 - Safety Zone; Liberty to Freedom Swims, Liberty Island, Upper Bay and Hudson River, NY

Federal Register 2010, 2011, 2012, 2013, 2014

2012-09-04

... 1625-AA00 Safety Zone; Liberty to Freedom Swims, Liberty Island, Upper Bay and Hudson River, NY AGENCY... September 5, 2012 and September 15, 2012 Liberty to Freedom swim events. This temporary safety zone is necessary to protect the maritime public and event participants from the hazards associated with swim events...

Elastic Properties of Orthoenstatite at Simultaneous High Pressure-Temperature Conditions and the Implication for the Origin of Low VP/VS Zones in the Mantle Wedge

NASA Astrophysics Data System (ADS)

Qian, W.; Wang, W.; Zou, F.; Wu, Z.

2017-12-01

The compositions of the Earth's interiors are critical in understanding the origin and evolution of the Earth and its geodynamics. Orthopyroxene is an important component for the upper mantle both in pyrolite model and in piclogite model. Furthermore, many evidences suggest the local enrichment of opx in the upper mantle. Therefore, its thermodynamic and elastic properties are fundamental for understanding of chemical compositions and dynamics of the upper mantle. We obtain the elastic properties of orthoenstatite (MgSiO3), Mg end-member orthopyroxene with space group Pbca, up to 20 GPa and 2000 K using first principles calculations with local density approximation (LDA). The calculated results are in good agreement with previous available experimental measurements and theoretical results. Both bulk and shear modulus show noticeable nonlinear pressure dependence, and the softening of shear wave velocities is prominent at high pressure. Meanwhile, orthoenstatite exhibits a negative temperature derivate of VP/VS ratios. This is different from other upper mantle minerals, such as olivine, ringwoodite and garnet, whose VP/VS increase with the increasing of the temperature. Compared to other major minerals in the upper mantle, orthoenstatite shows the lowest compressional velocities, shear velocities, and VP/VS (<1.7) ratio up to the depth of 200 km. Recently, many seismic studies have observed unusual low VP/VS (below 1.72) zones in subduction mantle wedge and orthopyroxene has been proposed to be a possible interpretation of this unusual observed. However, this explanation is still under debate because no experimental or calculated elastic data at the conditions of the upper mantle are available before. Our calculations show that VS and VP/VS ratio of orthoenstatite under the mantle wedge conditions (2-3 GPa and 1073-1723 K) are consistent of the unusual seismic observations of VP/VS in subduction mantle wedge. Therefore, the enrichment of orthopyroxene may potentially account for the observed low VP/VS in the mantle wedge.

Application of Remote-Sensing Observations for Detecting Patterns of Localization of PGM Mineralization of Western Bushveld

NASA Astrophysics Data System (ADS)

Milovsky, G. A.; Ishmukhametova, V. T.; Orlyankin, V. N.; Shemyakina, E. M.

2017-12-01

The differentiated Bushveld complex is studied by remote-space and gravimagnetic methods. The syncline of Western Bushveld is recognized in the southwestern part of the complex, which is characterized by a radial and ring structure of the higher order. The structures, which control the localization of Pt mineralization, are revealed and the possible use of the Landsat 7 ETM+ multizonal space survey is shown for recognizing the rocks of the Basal, Critical, Main, and Upper zones of the norite complex of Western Bushveld.

An object-oriented model of the cardiopulmonary system with emphasis on the gravity effect.

PubMed

Chuong Ngo; Herranz, Silvia Briones; Misgeld, Berno; Vollmer, Thomas; Leonhardt, Steffen

2016-08-01

We introduce a novel comprehensive model of the cardiopulmonary system with emphasis on perfusion and ventilation distribution along the vertical thorax axis under the gravity effect. By using an object-oriented environment, the complex physiological system can be represented by a network of electrical, lumped-element compartments. The lungs are divided into three zones: upper, middle, and lower zone. Blood flow increases with the distance from the apex to the base of the lungs. The upper zone is characterized by a complete collapse of the pulmonary capillary vasculature; thus, there is no flow in this zone. The second zone has a "waterfall effect" where the blood flow is determined by the difference between the pulmonary-arterial and alveolar pressures. At resting position, the upper lobes of the lungs are more expanded than the middle and lower lobes. However, during spontaneous breathing, ventilation is nonuniform with more air entering the lower lobes than the middle and upper lobes. A simulative model of the complete system is developed which shows results in good agreement with the literature.

Topographic Control of Aboveground Carbon Pools Across an Environmental Gradient, Eastern Slope of the Rocky Mountains, Colorado.

NASA Astrophysics Data System (ADS)

Swetnam, T. L.; Brooks, P. D.; Gallo, E. L.; Barnard, H. R.; Harpold, A. A.

2015-12-01

Evaluating at high spatial-resolution the topographical and ecological structures of the critical zone (CZ) are now routine with aerial LiDAR. Here we evaluated the eco-hydrological differences of topographic metrics (the independent variables) versus individual tree and gridded aboveground carbon (AGC) pools (as dependent variables) at multiple length-scales across an elevation modified gradient of precipitation and temperature in the Boulder Creek CZ Observatory Watershed, Colorado USA. We describe the responses in AGC within the context of a three-zone eco-hydrological model, e.g. toe slope and valley bottoms (Zone 1), transitional hillslopes (Zone 2), and upper slopes to ridges (Zone 3). In a GIS we compared three separate zero-order basins: (1) the Betasso Preserve: 1,810-2,024 meters above mean sea level (m aμsl), area = 0.45 km2, n = 17,286 trees; (2) Upper and Lower Gordon Gulch: 2,446-2,737 m aμsl, area = 3.57 km2, n = 178,469 trees; and (3) Como Creek: 2,900m-3,560 m aμsl, area = 6.64 km2, n = 317,274 trees. In each of the three catchments Zone 1 held the greatest mean AGC (μ = 52.88-60.97 Mg C ha-1) and maximum AGC (99% confidence interval (CI, p = 0.01) = 152.95-184.95 Mg C ha-1) relative to Zone 2 (μ = 27.84-44.52 Mg C ha-1, 99% CI = 99.67-122.4 Mg C ha-1) and Zone 3 (μ = 12.63-30.33 Mg C ha-1, 99% CI = 62.16-92.65 Mg C ha-1). Topography with negative general curvatures (i.e. convergent shapes) had greater AGC (μ = 73.7-96.3 Mg C ha-1, 99% CI = 189.0-355.8 Mg C ha-1) than positive general curvatures (i.e. divergent shapes) (μ = 17.4-30.8 Mg C ha-1, 99% CI = 88.2-120.4 Mg C ha-1), but only when evaluated at longer length scales (<10 m). Larger AGC pools are postulated to be related to (1) increased soil depth which provides larger rooting zones and (2) access to groundwater along Zone 1, vs Zones 2 and 3 which have (a) shallower soils and (b) less or zero accessibility to groundwater.

Uranium Bio-accumulation and Cycling as revealed by Uranium Isotopes in Naturally Reduced Sediments from the Upper Colorado River Basin

NASA Astrophysics Data System (ADS)

Lefebvre, Pierre; Noël, Vincent; Jemison, Noah; Weaver, Karrie; Bargar, John; Maher, Kate

2016-04-01

Uranium (U) groundwater contamination following oxidized U(VI) releases from weathering of mine tailings is a major concern at numerous sites across the Upper Colorado River Basin (CRB), USA. Uranium(IV)-bearing solids accumulated within naturally reduced zones (NRZs) characterized by elevated organic carbon and iron sulfide compounds. Subsequent re-oxidation of U(IV)solid to U(VI)aqueous then controls the release to groundwater and surface water, resulting in plume persistence and raising public health concerns. Thus, understanding the extent of uranium oxidation and reduction within NRZs is critical for assessing the persistence of the groundwater contamination. In this study, we measured solid-phase uranium isotope fractionation (δ238/235U) of sedimentary core samples from four study sites (Shiprock, NM, Grand Junction, Rifle and Naturita, CO) using a multi-collector inductively coupled plasma mass spectrometer (MC-ICP-MS). We observe a strong correlation between U accumulation and the extent of isotopic fractionation, with Δ238U up to +1.8 ‰ between uranium-enriched and low concentration zones. The enrichment in the heavy isotopes within the NRZs appears to be especially important in the vadose zone, which is subject to variations in water table depth. According to previous studies, this isotopic signature is consistent with biotic reduction processes associated with metal-reducing bacteria. Positive correlations between the amount of iron sulfides and the accumulation of reduced uranium underline the importance of sulfate-reducing conditions for U(IV) retention. Furthermore, the positive fractionation associated with U reduction observed across all sites despite some variations in magnitude due to site characteristics, shows a regional trend across the Colorado River Basin. The maximum extent of 238U enrichment observed in the NRZ proximal to the water table further suggests that the redox cycling of uranium, with net release of U(VI) to the groundwater by non-fractionating oxidation, is occurring within this zone. Thus, release of uranium from the NRZs may play a critical role in the persistence of groundwater contamination at these sites.

System and method for producing metallic iron

DOEpatents

Bleifuss, Rodney L [Grand Rapids, MN; Englund, David J [Bovey, MN; Iwasaki, Iwao [Grand Rapids, MN; Fosnacht, Donald R [Hermantown, MN; Brandon, Mark M [Charlotte, NC; True, Bradford G [Charlotte, NC

2012-01-17

A hearth furnace 10 for producing metallic iron material has a furnace housing 11 having a drying/preheat zone 12, a conversion zone 13, a fusion zone 14, and optionally a cooling zone 15, the conversion zone 13 is between the drying/preheat zone 12 and the fusion zone 14. A moving hearth 20 is positioned within the furnace housing 11. A hood or separation barrier 30 within at least a portion of the conversion zone 13, fusion zone 14 or both separates the fusion zone 14 into an upper region and a lower region with the lower region adjacent the hearth 20 and the upper region adjacent the lower region and spaced from the hearth 20. An injector introduces a gaseous reductant into the lower region adjacent the hearth 20. A combustion region may be formed above the hood or separation barrier.

Seismic refraction studies of volcanic crust in Costa Rica and of critical zones in the southern Sierra Nevada, California and Laramie Range, Wyoming

NASA Astrophysics Data System (ADS)

Hayes, Jorden L.

This work demonstrates the utility of seismic refraction surveys to understanding geologic processes at a range of scales. Each chapter presents subsurface maps of seismic p-wave velocities, which vary due to contrasts in elastic material properties. In the following chapters we examine seismic p-wave velocity variations that result from volcanic and tectonic processes within Earth's crust and chemical and physical weathering processes within Earth's near-surface environment. Chapter one presents results from an across-arc wide-angle seismic refraction survey of the Costa Rican volcanic front. These results support the hypothesis that juvenile continental crust may form along volcanic island arcs if built upon relatively thick substrates (i.e., large igneous provinces). Comparisons of velocity-depth functions show that velocities within the active arc of Costa Rica are lower than other modern island arcs (i.e., volcanic arcs built upon oceanic crust) and within the high-velocity extreme of bulk continental crust. Chapter two shows that physical processes can dominate over chemical processes in generating porosity in the deep critical zone and outlines a new framework for interpreting subsurface chemical and physical weathering at the landscape scale. Direct measurements of saprolite from boreholes at the Southern Sierra Nevada Critical Zone Observatory show that, contrary to convention, saprolite may experience high levels of volumetric strain (>35%) and uniform mass loss in the upper 11 m. By combining observations from boreholes and seismic refraction surveys we create a map of volumetric strain across the landscape. Variations in inferred volumetric strain are consistent with opening-mode fracture patterns predicted by topographic and tectonic stress models. Chapter three is a characterization of fracture distribution in the deep critical zone from geophysical and borehole observations in the Laramie Mountains, Wyoming. Data from core and down-hole acoustic televiewer images show that fracture density not only decreases with depth but also varies with topography. Comparisons of seismic p-wave velocities and fracture density show that increases in seismic velocity at our site (i.e., from 1-4 km/s) correspond to decreasing fracture density. Observations of a seismological boundary layer coupled with weathering interpreted in borehole images suggest a significant change in chemical weathering with depth. These results emphasize the complex interplay of chemical and physical processes in the deep critical zone.

Geologic and hydrologic control of chloride contamination in aquifers at Brunswick, Glynn County, Georgia

USGS Publications Warehouse

Gregg, Dean O.; Zimmerman, Everett Alfred

1974-01-01

Water from a brackish-water zone (1,050-1,350 ft) has concentrations as high as 2,150 milligrams per liter chloride, and concentrations are suspected to be higher than 3,000 milligrams per liter chloride. This brackish water has been identified as the source of the water that contaminates the upper and lower fresh-water-bearing zones of the principal artesian aquifer. The confining unit separating the fresh and brackish water seems to contain breaks that act as vertical conduits for the movement of brackish water into the fresh-water zones of the aquifer. Faults are suspected to be responsible for the breaks in the confining unit. The rate of upward movement of brackish water seems to be a function of the rate of water-level decline in the aquifer. There are two main areas of brackish-water intrusion. One area is near Bay and Prince Streets, and the other area is near Reynolds and Q Streets. Successive maps showing chloride ion concentration trace the movement of the chloride front northward in the Bay Street area at the rate of about 350 feet per year toward the center of pumping. An average of about 400 gallons per minute of water containing 2,000 milligrams per liter chloride invaded the upper water-bearing zone between December 1962 and December 1966. A like amount may have entered the lower water-bearing zone. Maximum chloride concentration in the upper water-bearing zone is 1,540 milligrams per liter in the Bay Street area and 640 milligrams per liter in the Reynolds Street area. In a few areas, where individual wells have been drilled deep enough to penetrate the confining unit over the brackish-water zone, the well furnishes a conduit for brackish water to recharge the fresh-water aquifer. Plugging the lower part of these wells usually reduces the chloride concentration of the water. The chloride concentration of water in the principal artesian aquifer can probably be reduced by use of interceptor wells, relief wells, or well-field spacing. Interceptor wells would prevent laterally moving brackish water from contaminating a well field. A relief well would tap and withdraw poor quality water from only the brackish-water zone to lower the head in that zone and decrease the rate of leakage into the fresh-water aquifer. Wider spacing of wells would prevent the development of a deep cone of depression and the steeper hydraulic gradients that accompany it. The brackish water pumped by the interceptor or relief wells could be used for industry, aquaculture, recreation, or for other processes in which the chloride content is not critical.

Upper crustal fault reactivation and the potential of triggered earthquakes on the Atacama Fault System, N-Chile

NASA Astrophysics Data System (ADS)

Victor, Pia; Ewiak, Oktawian; Thomas, Ziegenhagen; Monika, Sobiesiak; Bernd, Schurr; Gabriel, Gonzalez; Onno, Oncken

2016-04-01

The Atacama Fault System (AFS) is an active trench-parallel fault system, located in the forearc of N-Chile directly above the subduction zone interface. Due to its well-exposed position in the hyper arid forearc of N-Chile it is the perfect target to investigate the interaction between the deformation cycle in the overriding forearc and the subduction zone seismic cycle of the underlying megathrust. Although the AFS and large parts of the upper crust are devoid of any noteworthy seismicity, at least three M=7 earthquakes in the past 10 ky have been documented in the paleoseismological record, demonstrating the potential of large events in the future. We apply a two-fold approach to explore fault activation and reactivation patterns through time and to investigate the triggering potential of upper crustal faults. 1) A new methodology using high-resolution topographic data allows us to investigate the number of past earthquakes for any given segment of the fault system as well as the amount of vertical displacement of the last increment. This provides us with a detailed dataset of past earthquake rupture of upper plate faults which is potentially linked to large subduction zone earthquakes. 2) The IPOC Creepmeter array (http://www.ipoc-network.org/index.php/observatory/creepmeter.html) provides us with high-resolution time series of fault displacement accumulation for 11 stations along the 4 most active branches of the AFS. This array monitors the displacement across the fault with 2 samples/min with a resolution of 1μm. Collocated seismometers record the seismicity at two of the creepmeters, whereas the regional seismicity is provided by the IPOC Seismological Networks. Continuous time series of the creepmeter stations since 2009 show that the shallow segments of the fault do not creep permanently. Instead the accumulation of permanent deformation occurs by triggered slip caused by local or remote earthquakes. The 2014 Mw=8.2 Pisagua Earthquake, located close to the creepmeter array, triggered large displacement events on all stations. Another event recorded on all stations was the 2010 Mw=8.8 Maule earthquake located 1500km south of the array. Exploring observations from both datasets, we can clearly state that triggering of upper crustal faults is observed for small-scale displacements. These findings allow us to speculate that the observed larger events in the past are likely being triggered events that require a critically prestressed condition of the target fault that is unclamped by stress changes triggered by large or potentially even small subduction zone earthquakes.

Hydrogeologic framework and geochemistry of the intermediate aquifer system in parts of Charlotte, De Soto, and Sarasota counties, Florida

USGS Publications Warehouse

Torres, A.E.; Sacks, L.A.; Yobbi, D.K.; Knochenmus, L.A.; Katz, B.G.

2001-01-01

The hydrogeologic framework underlying the 600-square-mile study area in Charlotte, De Soto, and Sarasota Counties, Florida, consists of the surficial aquifer system, the intermediate aquifer system, and the Upper Floridan aquifer. The hydrogeologic framework and the geochemical processes controlling ground-water composition were evaluated for the study area. Particular emphasis was given to the analysis of hydrogeologic and geochemical data for the intermediate aquifer system. Flow regimes are not well understood in the intermediate aquifer system; therefore, hydrogeologic and geochemical information were used to evaluate connections between permeable zones within the intermediate aquifer system and between overlying and underlying aquifer systems. Knowledge of these connections will ultimately help to protect ground-water quality in the intermediate aquifer system. The hydrogeology was interpreted from lithologic and geophysical logs, water levels, hydraulic properties, and water quality from six separate well sites. Water-quality samples were collected from wells located along six ground-water flow paths and finished at different depth intervals. The selection of flow paths was based on current potentiometric-surface maps. Ground-water samples were analyzed for major ions; field parameters (temperature, pH, specific conductance, and alkalinity); stable isotopes (deuterium, oxygen-18, and carbon-13); and radioactive isotopes (tritium and carbon-14). The surficial aquifer system is the uppermost aquifer, is unconfined, relatively thin, and consists of unconsolidated sand, shell, and limestone. The intermediate aquifer system underlies the surficial aquifer system and is composed of clastic sediments interbedded with carbonate rocks. The intermediate aquifer system is divided into three permeable zones, the Tamiami/Peace River zone (PZ1), the Upper Arcadia zone (PZ2), and the Lower Arcadia zone (PZ3). The Tamiami/Peace River zone (PZ1) is the uppermost zone and is the thinnest and generally, the least productive zone in the intermediate aquifer system. The Upper Arcadia zone (PZ2) is the middle zone and productivity is generally higher than the overlying permeable zone. The Lower Arcadia zone (PZ3) is the lowermost permeable zone and is the most productive zone in the intermediate aquifer system. The intermediate aquifer system is underlain by the Upper Floridan aquifer, which consists of a thick, stratified sequence of limestone and dolomite. The Upper Floridan aquifer is the most productive aquifer in the study area; however, its use is generally restricted because of poor water quality. Interbedded clays and fine-grained clastics separate the aquifer systems and permeable zones. The hydraulic properties of the three aquifer systems are spatially variable. Estimated trans-missivity and horizontal hydraulic conductivity varies from 752 to 32,900 feet squared per day and from 33 to 1,490 feet per day, respectively, for the surficial aquifer system; from 47 to 5,420 feet squared per day and from 2 to 102 feet per day, respectively, for the Tamiami/Peace River zone (PZ1); from 258 to 24,633 feet squared per day and from 2 to 14 feet per day, respectively, for the Upper Arcadia zone (PZ2); from 766 to 44,900 feet squared per day and from 10 to 201 feet per day, respectively, for the Lower Arcadia zone (PZ3); and from 2,350 to 7,640 feet squared per day and from 10 to 41 feet per day, respectively, for the Upper Floridan aquifer. Confining units separating the aquifer systems have leakance coefficients estimated to range from 2.3 x 10-5 to 5.6 x 10-3 feet per day per foot. Strata composing the confining unit separating the Upper Floridan aquifer from the intermediate aquifer system are substantially more permeable than confining units separating the permeable zones in the intermediate aquifer system or separating the surficial aquifer and intermediate aquifer systems. In Charlotte, Sarasota, and western De Soto Counties, hydraulic

Summary of hydrologic testing of the Floridan aquifer system at Fort Stewart, Georgia

USGS Publications Warehouse

Gonthier, Gerard

2011-01-01

Flowmeter surveys at the study site indicate several permeable zones within the Floridan aquifer system. The Upper Floridan aquifer is composed of two water-bearing zones-the upper zone and the lower zone. The upper zone extends from 520 to 650 feet below land surface, contributes 96 percent of the total flow, and is more permeable than the lower zone, which extends from 650 to 705 feet below land surface and contributes the remaining 4 percent of the flow. The Lower Floridan aquifer consists of three zones at depths of 912-947, 1,090-1,139, and 1,211-1,250 feet below land surface that are inter-layered with three less-permeable zones. The Lower Floridan confining unit includes a permeable zone that extends from 793 to 822 feet below land surface. Horizontal hydraulic conductivity values of the Lower Floridan confining unit derived from slug tests within four packer-isolated intervals were from 2 to 20 feet per day, with a high value of 70 feet per day obtained for one of the intervals. Aquifer testing, using analytical techniques and model simulation, indicated the Upper Floridan aquifer had a transmissivity of about 100,000 feet squared per day, and the Lower Floridan aquifer had a transmissivity of 7,000 feet squared per day. Flowmeter surveys, slug tests within packer-isolated intervals, and parameter-estimation results indicate that the hydraulic properties of the Lower Floridan confining unit are similar to those of the Lower Floridan aquifer. Water-level data, for each aquifer test, were filtered for external influences such as barometric pressure, earth-tide effects, and long-term trends to enable detection of small water-level responses to aquifer-test pumping of less than 1 foot. During a 72-hour aquifer test of the Lower Floridan aquifer, a drawdown response of 0.3 to 0.4 foot was observed in two Upper Floridan aquifer wells, one of which was more than 1 mile away from the pumped well.

75 FR 53963 - Iron Mask Hydro, LLC; Notice of Preliminary Permit Application Accepted for Filing and Soliciting...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-09-02

...-long upper dam made of either zoned earth and rockfill or concrete-face earth and rockfill; (2) a 50-foot-high, 950-foot-long earth-filled upper saddle dike A; (3) a 20-foot-high, 400-foot-long earth-filled upper saddle dike B; (4) a 40-foot-high, 6,559-foot-long lower embankment made of zoned earth or...

Aqueous Silicate Polymers: An Alternative to `Supercritical' Fluids as Transport Agents in Subduction Zones

NASA Astrophysics Data System (ADS)

Mannig, C. E.

2005-12-01

The chemistry of subduction-zone fluids is complicated by melt-vapor miscibility and the existence of critical end-points in rock-H2O systems. It is commonly assumed that fluids in subduction zones attain properties intermediate in composition between hydrous silicate liquid and H2O, and that such fluids possess enhanced material transport capabilities. However, the relevance of supercritical, intermediate fluids to subduction zones presents four problems. (1) Albite-H2O is typically used as an analogue system, but the favorable position of its critical curve is not representative; critical curves for polymineralic subduction-zone lithologies lie at substantially higher P. (2) Even if albite-H2O is relevant, jadeite may interfere because of its different solubility and the positive clapeyron slope of its solidus, which points to liquid-structure changes that could cause reappearance of the liquid+vapor field. (3) Critical curves are features of very H2O-rich compositions; low-porosity, H2O-poor natural systems will coexist with intermediate fluids only over a narrow PT interval. (4) Intermediate fluids are expected only over short length scales because their migration will likely result in compositional shifts via reaction and mineral precipitation in the mantle wedge. Although supercritical, intermediate fluids are probably relatively unimportant in subduction zones, they reflect a chemical process that may hold the key to understanding high- P mass transfer. Miscibility in melt-vapor systems is a consequence of polymerization of dissolved components, primarily Si ± Al, Na and Ca. This behavior yields, e.g., aqueous Si-Si, Si-Al, Si-Na-Al, and Si-Ca oxide dimers and other multimers of varying stoichiometry (silicate polymers), even in subcritical, dilute, H2O-rich vapor. Silicate polymers in subcritical aqueous solutions have been inferred from high- P mineral-solubility experiments. The abundance of these species at high P shows that the chemistry of aqueous fluids in subduction-zones differs fundamentally from the more familiar ionic solutions of the upper crust. This has important consequences for minor element transport. Measurements of Fe, phosphorous and Ti solubility reveal that dissolved concentrations rise with increased aqueous albite content at fixed P and T, with maximum enhancements exceeding 10X at melt saturation. Subcritical silicate polymerization thus permits transport of low solubility components via their substitution into sites on aqueous multimers constructed of "polymer formers" such as Na, Al, and Si, even in dilute solutions. The partitioning of elements between the bulk fluid, the polymer network, and the rock matrix likely controls the overall compositional evolution of subduction-zone fluids. Because they form over a wider PT and bulk X range, subcritical silicate polymers in dilute solutions are likely responsible for more mass transfer in subduction zones than intermediate, supercritical fluids.

Upper Cretaceous planktonic stratigraphy of the Göynük composite section, western Tethys (Bolu province, Turkey)

NASA Astrophysics Data System (ADS)

Wolfgring, Erik; Liu, Shasha; Wagreich, Michael; Böhm, Katharina; Omer Yilmaz, Ismail

2017-04-01

Upper Cretaceous strata exposed at Göynük (Mudurnu-Göynük basin, Bolu Province, Northwestern Anatolia, Turkey) provide a composite geological record from the Upper Santonian to the Maastrichtian. Deposits in this area originate from the Sakarya continent, therefore, a western Tethyan palaeogeographic setting with a palaeolatitude of a bit less than 30 degrees north can be reconstructed. Grey shales and clayey marls are exposed at Göynük and do frequently show volcanic intercalations in the oldest parts of the section, while the uppermost layers depict a more complete deeper-marine record. The pelagic palaeoenvironment, microfossil indicators point towards a distal slope setting, at the Göynük section comprises rich low-latitude planktonic foraminiferal and calcareous nannoplankton assemblages. Benthic foraminifera are scarce, however, some biostratigraphically indicative taxa were recovered. The three sections sampled for this study reveal a composite record from the Campanian Contusotruncana plummerae planktonic foraminifera Zone to the Maastrichtian Racemiguembelina fruticosa planktonic foraminifera Zone. The oldest sub section („GK-section") yields the „mid" Campanian Contusotruncana plummerae or Globotruncana ventricosa Zones and is followed by the „GC-section". The oldest strata in latter record the C. plummerae Zone, the Radotruncana calcarata Zone, Globotruncanita havanensis as well as the Globotruncana aegyptiaca Zone and are overlain by the youngest section examined in this study ("GS -section"). In the latter, we recognize the G. aegyptiaca Zone in the lowermost part, the upper Campanian/lower Maastrichtian Gansserina gansseri Zone, and the Maastrichtian Racemiguembelina fruticosa Zone. Nannofossil standard zones UC15b to UC18 are recorded within the composite section. The planktonic foraminiferal assemblages assessed in the Göynük area feature a well preserved, diverse plankton record that can be correlated to other western Tethyan sections from the Upper Cretaceous. Especially the Austrian Alpine sections (i.e. Northern Calcareous Alps and Ultrahelvetics) show similar environmental and palaeolatitudinal settings and feature a well established biostratigraphical and cyclostratigraphic record. Comparing the multi-proxy record assessed in these sections to the biostratigraphic data from the Göynük region provides useful insights into planktonic foraminiferal palaeoecology and the multistratigraphic high-resolution correlation in the Upper Cretaceous Tethyan realm.

Paleontology and physical stratigraphy of the USGS-Pregnall No. 1 core (DOR-208), Dorchester County, South Carolina

USGS Publications Warehouse

Edwards, L.E.; Bybell, L.M.; Gohn, G.S.; Frederiksen, N.O.

1997-01-01

Pregnall No. 1, a 346-ft-deep corehole in northern Dorchester County, South Carolina, recovered sediments of late Paleocene, middle and late Eocene, and late Oligocene age. The core bottomed in the Chicora Member of the Williamsburg Formation (Black Mingo Group) of late Paleocene age (calcareous nannofossil Zones NP 7/8 (?) and NP 9). The Chicora (346 to 258 ft depth) consists of two contrasting lithologic units, a lower siliciclastic section of terrigenous sand, silt, and clay, and an upper carbonate section of moldic pelecypod limestone. The Chicora is overlain unconformably by the middle Eocene Moultrie Member of the Santee Limestone (Orangeburg Group). The Moultrie (258.0 to 189.4 ft) consists primarily of bryozoan-pelecypod-peloid packstones and grainstones, which are assigned to calcareous nannofossil Zone NP 16. Unconformably above the Moultrie are the locally shelly, microfossiliferous limestones of the Cross Member of the Santee Limestone (Orangeburg Group), which are assigned to middle Eocene Zone NP 17 and upper Eocene Zone NP 18. The Cross Member (189.4 to 90.9 ft) is unconformably overlain by a very thin, basal section of the upper Eocene Harleyville Formation (Cooper Group). The thin Harleyville section consists of fossiliferous limestone, primarily pelecypod-foraminifer-peloid packstones (90.9 to 85.8 ft), and is assigned to Zone NP 18, although samples from thicker Harleyville sections in the region typically are assigned to upper Eocene Zone NP 19/20. The Harleyville is overlain unconformably by the upper Oligocene Ashley Formation (Cooper Group). The Ashley Formation (85.8 to 30.0 ft) consists of a relatively homogeneous section of calcareous, microfossiliferous, silty and sandy clays assigned to Zones NP 24 and NP 25 (?). Neogene and (or) Quaternary deposits present in the upper 30 ft of the Pregnall section are assigned provisionally to an unnamed unit (30 to 22 ft) and to the Waccamaw Formation(?)(22 to 0 ft).

Chloride Concentration in Water from the Upper Permeable Zone of the Tertiary Limestone Aquifer System, Southeastern United States

USGS Publications Warehouse

Sprinkle, Craig L.

1982-01-01

INTRODUCTION The tertiary limestone aquifer system of the southeastern United States is a sequence of carbonate rocks referred to as the Floridan aquifer in Florida and the principal artesian aquifer in Georgia, Alabama, and South Carolina. More than 3 billion gallons of water are pumped daily from the limestone aquifer; and the system is the principal source of municipal, industrial, and agricultural water supply in south Georgia and most of Florida. The aquifer system includes units of Paleocene to early Miocene age that combine to form a continuous carbonate sequence that is hydraulically connected in varying degrees. In a small area near Brunswick, Ga., a thin sequence of rocks of Late Cretaceous age is part of the system. In and directly downdip from much of the outcrop area, the system consists of one continuous permeable unit. Further downdip the aquifer system generally consists of two major permeable zones separated by a less-permeable unit of highly variable hydraulic properties (very leaky to virtually nonleaky). Conditions for the system vary from unconfined to confined depending upon whether the argillaceous Miocene and younger rocks that form the upper confining unit have been removed by erosion. This report is one of a series of preliminary products depicting the hydrogeologic framework, water chemistry, and hydrology of the aquifer system. The map shows the distribution of chloride ions in water from the upper permeable zone of the limestone aquifer system. The upper permeable zone consists of several formations, primarily the Tampa, Suwannee, Ocala, and Avon Park Limestones (Miller 1981a, b). Chloride concentrations of water within the upper permeable zone vary from nearly zero in recharge areas to many thousands of milligrams per liter (mg/L) in coastal discharge areas. Where the aquifer system discharges into the sea, the upper permeable zone contains increasing amounts of seawater. In these areas, wells that fully penetrate the upper permeable zone will yield water with chloride concentrations that approach that of seawater, about 19500 mg/L.

Silurian and Devonian in Vietnam—Stratigraphy and facies

NASA Astrophysics Data System (ADS)

Thanh, Tống Duy; Phương, Tạ Hoàng; Janvier, Philippe; Hùng, Nguyễn Hữu; Cúc, Nguyễn Thị Thu; Dương, Nguyễn Thùy

2013-09-01

Silurian and Devonian deposits in Viet Nam are present in several zones and regions, including Quang Ninh, East Bac Bo, and West Bac Bo Zones of the Bac Bo Region, the Dien Bien-Nghe An and Binh Tri Thien Zones of the Viet-Lao Region, and the South Trung Bo, and Western Nam Bo Zones of the South Viet Nam Region (Fig. 1). The main lithological features and faunal composition of the Silurian and Devonian Units in all these zones are briefly described. The Silurian consists of deep-water deposits of the upper parts of the Co To and Tan Mai Formations in the Quang Ninh Zone, the upper parts of the Phu Ngu Formation in the East Bac Bo Zone and the upper parts of the Long Dai and Song Ca Formations in the Viet-Lao Region. Shallow water facies Silurian units containing benthic faunas are more widely distributed, including the upper part of the Sinh Vinh and Bo Hieng Formations in the West Bac Bo Zone, the Kien An Formation in the Quang Ninh Zone, and, in the Viet-Lao Region, the Dai Giang Formation and the upper part of the Tay Trang Formation. No Lower and Middle Devonian deposits indicate deep water facies, but they are characterized by different shallow water facies. Continental to near shore, deltaic facies characterize the Lower Devonian Song Cau Group in the East Bac Bo Zone, the Van Canh Formation in the Quang Ninh Zone, and the A Choc Formation in the Binh Tri Thien Zone. Similar facies also occur in the Givetian Do Son Formation of the Quang Ninh Zone, and the Tan Lap Formation in the East Bac Bo Zone, and consist of coarse terrigenous deposits—cross-bedded conglomerates, sandstone, etc. Most Devonian units are characterized by shallow marine shelf facies. Carbonate and terrigenous-carbonate facies dominate, and terrigenous facies occur in the Lower and Middle Devonian sections in some areas only. The deep-water-like facies is characteriztic for some Upper Devonian formations in the Bac Bo (Bang Ca and Toc Tat Formations) and Viet-Lao Regions (Thien Nhan and Xom Nha Formations). These formations contain cherty shale or siliceous limestone, and fossils consist of conodonts, but there are also brachiopods and other benthos. They were possibly deposited in a deep water environment on the slope of the continental shelf. Most Devonian units distributed in the North and the Central Viet Nam consist of self shallow water sediments, and apparently they were deposited in a passive marginal marine environment. The coarse clastic continental or subcontinental deposits are distributed only in some areas of the East Bac Bo and of the Quang Ninh zones of the Bac Bo Region, and in the south of the Binh Tri Thien Zone. This situation suggests the influence of the Caledonian movement at the end of the Silurian period that called the Guangxi movement in South China.

Perfusion Scintigraphy and Patient Selection for Lung Volume Reduction Surgery

PubMed Central

Chandra, Divay; Lipson, David A.; Hoffman, Eric A.; Hansen-Flaschen, John; Sciurba, Frank C.; DeCamp, Malcolm M.; Reilly, John J.; Washko, George R.

2010-01-01

Rationale: It is unclear if lung perfusion can predict response to lung volume reduction surgery (LVRS). Objectives: To study the role of perfusion scintigraphy in patient selection for LVRS. Methods: We performed an intention-to-treat analysis of 1,045 of 1,218 patients enrolled in the National Emphysema Treatment Trial who were non–high risk for LVRS and had complete perfusion scintigraphy results at baseline. The median follow-up was 6.0 years. Patients were classified as having upper or non–upper lobe–predominant emphysema on visual examination of the chest computed tomography and high or low exercise capacity on cardiopulmonary exercise testing at baseline. Low upper zone perfusion was defined as less than 20% of total lung perfusion distributed to the upper third of both lungs as measured on perfusion scintigraphy. Measurements and Main Results: Among 284 of 1,045 patients with upper lobe–predominant emphysema and low exercise capacity at baseline, the 202 with low upper zone perfusion had lower mortality with LVRS versus medical management (risk ratio [RR], 0.56; P = 0.008) unlike the remaining 82 with high perfusion where mortality was unchanged (RR, 0.97; P = 0.62). Similarly, among 404 of 1,045 patients with upper lobe–predominant emphysema and high exercise capacity, the 278 with low upper zone perfusion had lower mortality with LVRS (RR, 0.70; P = 0.02) unlike the remaining 126 with high perfusion (RR, 1.05; P = 1.00). Among the 357 patients with non–upper lobe–predominant emphysema (75 with low and 282 with high exercise capacity) there was no improvement in survival with LVRS and measurement of upper zone perfusion did not contribute new prognostic information. Conclusions: Compared with optimal medical management, LVRS reduces mortality in patients with upper lobe–predominant emphysema when there is low rather than high perfusion to the upper lung. PMID:20538961

Lithostratigraphy, biostratigraphy and chemostratigraphy of Upper Cretaceous sediments from southern Tanzania: Tanzania drilling project sites 21-26

NASA Astrophysics Data System (ADS)

Jiménez Berrocoso, Álvaro; MacLeod, Kenneth G.; Huber, Brian T.; Lees, Jacqueline A.; Wendler, Ines; Bown, Paul R.; Mweneinda, Amina K.; Isaza Londoño, Carolina; Singano, Joyce M.

2010-04-01

The 2007 drilling season by the Tanzania drilling project (TDP) reveals a much more expanded Upper Cretaceous sequence than was recognized previously in the Lindi region of southern Tanzania. This TDP expedition targeted recovery of excellently preserved microfossils (foraminifera and calcareous nannofossils) for Late Cretaceous paleoclimatic, paleoceanographic and biostratigraphic studies. A total of 501.17 m of core was drilled at six Upper Cretaceous sites (TDP Sites 21, 22, 23, 24, 24B and 26) and a thin Miocene-Pleistocene section (TDP Site 25). Microfossil preservation at all these sites is good to excellent, with foraminifera often showing glassy shells and consistently good preservation of small and delicate nannofossil taxa. In addition to adding to our knowledge of the subsurface geology, new surface exposures were mapped and the geological map of the region is revised herein. TDP Sites 24, 24B and 26 collectively span the upper Albian to lower-middle Turonian (planktonic foraminiferal Planomalina buxtorfi- Whiteinella archaeocretacea Zones and calcareous nannofossil zones UC0a-UC8a). The bottom of TDP Site 21 is barren, but the rest of the section represents the uppermost Cenomanian-Coniacian ( W. archaeocretacea- Dicarinella concavata Zones and nannofossil zones UC5c-UC10). Bulk organic δ 13C data suggest recovery of part of Ocean Anoxic Event 2 (OAE2) from these four sites. In the upper part of this interval, the lower Turonian nannofossil zones UC6a-7 are characterized by a low-diversity nannoflora that may be related to OAE2 surface-water conditions. TDP Site 22 presents a 122-m-thick, lower-middle Turonian ( W. archaeocretacea- Helvetoglobotruncana helvetica Zones) sequence that includes the nannofossil zones UC6a(-7?), but invariable isotopic curves. Further, a lower to upper Campanian ( Globotruncana ventricosa- Radotruncana calcarata Zones and nannofossil subzones UC15b TP-UC15d TP) succession was drilled at TDP Site 23. Lithologies of the new sites include thin units of gray, medium to coarse sandstones, separating much thicker intervals of dark claystones with organic-rich laminated parts, irregular silty to fine sandstone partings, and rare inoceramid and ammonite debris. These lithofacies are interpreted to have been deposited in outer shelf and upper slope settings and indicate relatively stable sedimentary conditions during most of the Late Cretaceous on the Tanzanian margin.

Space-time mapping of wasting among children under the age of five years in Somalia from 2007 to 2010.

PubMed

Kinyoki, Damaris K; Berkley, James A; Moloney, Grainne M; Odundo, Elijah O; Kandala, Ngianga-Bakwin; Noor, Abdisalan M

2016-02-01

To determine the sub-national seasonal prevalence and trends in wasting from 2007 to 2010 among children aged 6-59 months in Somalia using remote sensing and household survey data from nutritional surveys. Bayesian hierarchical space-time model was implemented using a stochastic partial differential equation (SPDE) approach in integrated nested Laplace approximations (INLA) to produce risk maps of wasting at 1 × 1 km(2) spatial resolution and predict to seasons in each year of study from 2007 to 2010. The prevalence of wasting was generally at critical levels throughout the country, with most of the areas remaining in the upper classes of critical and very critical levels. There was minimal variation in wasting from year-to-year, but a well-defined seasonal variation was observed. The mean difference of the prevalence of wasting between the dry and wet season ranges from 0% to 5%. The risks of wasting in the South Central zone were highest in the Gedo (37%) and Bay (32%) regions. In North East zone the risk was highest in Nugaal (25%) and in the North West zone the risk was high in Awdal and Woqooyi Galbeed regions with 23%. There was a clear seasonal variation in wasting with minimal year-to-year variability from 2007 to 2010 in Somalia. The prevalence was high during the long dry season, which affects the prevalence in the preceding long rainy season. Understanding the seasonal fluctuations of wasting in different locations and at different times is important to inform timely interventions. Copyright © 2016. Published by Elsevier Ltd.

Estimating Strain Accumulation in the New Madrid and Wabash Valley Seismic Zones

NASA Astrophysics Data System (ADS)

Craig, T. J.; Calais, E.

2014-12-01

The mechanical behaviour -- and hence earthquake potential -- of faults in continental interiors is a question of critical importance for the resultant seismic hazard, but no consensus has yet been reached on this controversial topic. The debate has focused on the central and eastern United States, in particular the New Madrid Seismic Zone, struck by three magnitude 7 or greater earthquakes in 1811--1812, and to a lesser extent the Wabash Valley Seismic Zone just to the north. A key aspect of this issue is the rate at which strain is currently accruing on those faults in the plate interior, a quantity that remains debated. Understanding if the present-day strain rates indicate sufficient motion to account for the historical and paleoseismological earthquakes by steady-state fault behaviour, or if strain accumulation is time-dependent in this area, is critical for investigating the causative process driving this seismicity in the plate interior, and how regional strain reflects the interplay between stresses arising from different geological processes. Here we address this issue with an analysis of up to 14 years of continuous GPS data from a network of 200 sites in the central United States centred on the New Madrid and Wabash Valley seismic zones. We find that high-quality sites in these regions show motions that are consistently within the 95% confidence limit of zero deformation relative to a rigid background. These results place an upper bound on regional strain accrual of 0.2 mm/yr and 0.5 mm/yr in the New Madrid and Wabash Valley Seismic Zones, respectively. These results, together with increasing evidence for temporal clustering and spatial migration of earthquake sequences in continental interiors, indicate that either tectonic loading rates or fault properties vary with time in the NMSZ and possibly plate-wide.

Hydrogeology and the distribution of salinity in the Floridan aquifer system, Palm Beach County, Florida

USGS Publications Warehouse

Reese, R.S.; Memberg, S.J.

2000-01-01

The virtually untapped Floridan aquifer system is considered to be a supplemental source of water for public use in the highly populated coastal area of Palm Beach County. A recent study was conducted to delineate the distribution of salinity in relation to the local hydrogeology and assess the potential processes that might control (or have affected) the distribution of salinity in the Floridan aquifer system. The Floridan aquifer system in the study area consists of the Upper Floridan aquifer, middle confining unit, and Lower Floridan aquifer and ranges in age from Paleocene to Oligocene. Included at its top is part of a lowermost Hawthorn Group unit referred to as the basal Hawthorn unit. The thickness of this basal unit is variable, ranging from about 30 to 355 feet; areas where this unit is thick were paleotopographic lows during deposition of the unit. The uppermost permeable zones in the Upper Floridan aquifer occur in close association with an unconformity at the base of the Hawthorn Group; however, the highest of these zones can be up in the basal unit. A dolomite unit of Eocene age generally marks the top of the Lower Floridan aquifer, but the top of this dolomite unit has a considerable altitude range: from about 1,200 to 2,300 feet below sea level. Additionally, where the dolomite unit is thick, its top is high and the middle confining unit of the Floridan aquifer system, as normally defined, probably is not present. An upper zone of brackish water and a lower zone of water with salinity similar to that of seawater (saline-water zone) are present in the Floridan aquifer system. The brackish-water and saline-water zones are separated by a transition zone (typically 100 to 200 feet thick) in which salinity rapidly increases with depth. The transition zone was defined by using a salinity of 10,000 mg/L (milligrams per liter) of dissolved-solids concentration (about 5,240 mg/L of chloride concentration) at its top and 35,000 mg/L of dissolved-solids concentration (about 18,900 mg/L of chloride concentration) at its base. The base of the brackish-water zone and the top of the saline-water zone were approximately determined mostly by means of resistivity geophysical logs. The base of the brackish-water zone in the study area ranges from about 1,600 feet below sea level near the coast to almost 2,200 feet below sea level in extreme southwestern Palm Beach County. In an area that is peripheral to Lake Okeechobee, the boundary unexpectedly rises to perhaps as shallow as 1,800 feet below sea level. In an upper interval of the brackish-water zone within the Upper Floridan aquifer, chloride concentration of water ranges from 490 to 8,000 mg/L. Chloride concentration correlates with the altitude of the basal contact of the Hawthorn Group, with concentration increasing as the altitude of this contact decreases. Several areas of anomalous salinity where chloride concentration in this upper interval is greater than 3,000 mg/L occur near the coast. In most of these areas, salinity was found to decrease with depth from the upper interval to a lower interval within the brackish-water zone: a reversal of the normal salinity trend within the zone. These areas are also characterized by an anomalously low altitude of the base of the brackish-water zone, and a much greater thickness of the transition zone than normal. These anomalies could be the result of seawater preferentially invading zones of higher permeability in the Upper Floridan aquifer during Pleistocene high stands of sea level and incomplete flushing of this high salinity water by the present-day flow system.

Seismic Tomography of the Arabian-Eurasian Collision Zone and Surrounding Areas

DTIC Science & Technology

2010-05-20

zone. The crustal models correlate well with geologic and tectonic features. The upper mantle tomograms show the images of the subducted Neotethys...We first obtain Pn and Sn velocities using local and regional arrival time data. Second, we obtain the 3-D crustal P and S velocity models...teleseismic tomography provides a high-resolution, 3-D P-wave velocity model for the crust, upper mantle, and the transition zone. The crustal models

Abrupt Upper-Plate Tilting Upon Slab-Transition-Zone Collision

NASA Astrophysics Data System (ADS)

Crameri, F.; Lithgow-Bertelloni, C. R.

2017-12-01

During its sinking, the remnant of a surface plate crosses and interacts with multiple boundaries in Earth's interior. The most-prominent dynamic interaction arises at the upper-mantle transition zone where the sinking plate is strongly affected by the higher-viscosity lower mantle. Within our numerical model, we unravel, for the first time, that this very collision of the sinking slab with the transition zone induces a sudden, dramatic downward tilt of the upper plate towards the subduction trench. The slab-transition zone collision sets parts of the higher-viscosity lower mantle in motion. Naturally, this then induces an overall larger return flow cell that, at its onset, tilts the upper plate abruptly by around 0.05 degrees and over around 10 Millions of years. Such a significant and abrupt variation in surface topography should be clearly visible in temporal geologic records of large-scale surface elevation and might explain continental-wide tilting as observed in Australia since the Eocene or North America during the Phanerozoic. Unravelling this crucial mantle-lithosphere interaction was possible thanks to state-of-the-art numerical modelling (powered by StagYY; Tackley 2008, PEPI) and post-processing (powered by StagLab; www.fabiocrameri.ch/software). The new model that is introduced here to study the dynamically self-consistent temporal evolution of subduction features accurate subduction-zone topography, robust single-sided plate sinking, stronger plates close to laboratory values, an upper-mantle phase transition and, crucially, simple continents at a free surface. A novel, fully-automated post-processing includes physical model diagnostics like slab geometry, mantle flow pattern, upper-plate tilt angle and trench location.

Method of operating a coal gasifier

DOEpatents

Blaskowski, Henry J.

1979-01-01

A method of operating an entrained flow coal gasifier which comprises the steps of firing coal at two levels in a combustion zone with near stoichiometric air, removing molten ash from the combustion zone, conveying combustion products upwardly from the combustion zone through a reduction zone, injecting additional coal into the combustion products in the reduction zone and gasifying at least a portion of the coal to form low BTU gas, conveying the gas to a point of use, including also reducing gasifier output by modifying the ratio of air to coal supplied to the upper level of the combustion zone so that the ratio becomes increasingly substoichiometric thereby extending the gasification of coal from the reduction zone into the upper level of the combustion zone, and maintaining the lower level of coal in the combustion zone at near stoichiometric conditions so as to provide sufficient heat to maintain effective slagging conditions.

Geology, hydrology, and water quality of the Tracy-Dos Palos area, San Joaquin Valley, California

USGS Publications Warehouse

Hotchkiss, W.R.; Balding, G.O.

1971-01-01

The Tracy-Dos Palos area includes about 1,800 square miles on the northwest side of the San Joaquin Valley. The Tulare Formation of Pliocene and Pleistocene age, terrace deposits of Pleistocene age, and alluvium and flood-basin deposits of Pleistocene and Holocene age constitute the fresh ground-water reservoir Pre-Tertiary and Tertiary sedimentary and crystalline rocks, undifferentiated, underlie the valley and yield saline water. Hydrologically most important, the Tulare Formation is divided into a lower water-bearing zone confined by the Corcoran Clay Member and an upper zone that is confined, semiconfined, and unconfined in different parts of the area. Alluvium and flood-basin deposits are included in the upper zone. Surficial alluvium and flood-basin deposits contain a shallow water-bearing zone. Lower zone wells were flowing in 1908, but subsequent irrigation development caused head declines and land subsidence. Overdraft in both zones ended in 1951 with import of surface water. Bicarbonate water flows into the area from the Sierra Nevada and Diablo Range. Diablo Range water is higher in sulfate, chloride, and dissolved solids. Upper zone water averages between 400 and 1,200 mg/l (milligrams per liter) dissolved solids and water hardness generally exceeds 180 mg/l as calcium carbonate. Nitrate, fluoride, iron, and boron occur in excessive concentrations in water from some wells. Dissolved constituents in lower zone water generally are sodium chloride and sodium sulfate with higher dissolved solids concentration than water from the upper zone. The foothills of the Diablo Range provide favorable conditions for artificial recharge, but shallow water problems plague about 50 percent of the area and artificial recharge is undesirable at this time.

Planktonic foraminifers and radiolarians from the Coniacian-santonian deposits of the Mt. Ak-Kaya, Crimean Mountains, Ukraine

NASA Astrophysics Data System (ADS)

Korchagin, O. A.; Bragina, L. G.; Bragin, N. Yu.

2012-02-01

The first data on the distribution of planktonic foraminifers and radiolarians in the Mt. Ak-Kaya section, the central Crimean Mountains, are considered. According to the analyzed distribution of foraminifers, the Upper Cretaceous deposits of the section are subdivided into three biostratigraphic units: the Marginotruncana austinensis-Globotruncana desioi (presumably upper Coniacian), Sigalia carpatica (uppermost Coniacian-lower Santonian), and Contusotruncana fornicata-Marginotruncana marginata (upper Santonian) beds. Subdivisions substantiated by distribution of radiolarians are the Alievium praegallowayi-Crucella plana (upper Coniacian-lower Santonian), Alievium gallowayi-Crucella espartoensis (the upper Santonian excluding its uppermost part), and Dictyocephalus (Dictyocryphalus) (?) legumen-Spongosaturninus parvulus (the uppermost Santonian) beds. The Contusotruncana fornicata-Marginotruncana marginata Beds are concurrent to the middle part of the Marsupites laevigatus Zone coupled with the Marsupites testudinarius Zone (the uppermost Santonian). The Alievium gallowayi-Crucella espartoensis Beds are correlative with the upper part of the Alievium gallowayi Zone in the Californian radiolarian zonation. The cooccurring assemblages of planktonic foraminifers and radiolarians provide a possibility to correlate the Coniacian-Santonian deposits within the Crimea-Caucasus region.

Results of coalbed-methane drilling, Mylan Park, Monongalia County, West Virginia: Chapter G.3 in Coal and petroleum resources in the Appalachian basin: distribution, geologic framework, and geochemical character

USGS Publications Warehouse

Ruppert, Leslie F.; Fedorko, Nick; Warwick, Peter D.; Grady, William C.; Britton, James Q.; Schuller, William A.; Crangle, Robert D.; Ruppert, Leslie F.; Ryder, Robert T.

2014-01-01

High-pressure carbon-dioxide adsorption isotherms were measured on composite coal samples of the Upper Kittanning coal bed and the Middle Kittanning and Clarion coal zones. Assuming that the reservoir pressure in the Mylan Park coals is equivalent to the normal hydrostatic pressure, the estimated maximum carbon-dioxide adsorption pressures range from a low of about 300 pounds per square inch (lb/in2 ) in coals from the Clarion coal zone to 500 lb/in2 for coals from the Upper Kittanning coal bed. The estimated maximum methane adsorption isotherms show that the coals from the Upper Kittanning coal bed and the Middle Kittanning coal zone are undersaturated in methane, but coals from the Clarion coal zone are close to saturation.

Upper crustal structure beneath East Java from ambient noise tomography: A preliminary result

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

Martha, Agustya Adi; Graduate Research on Earthquakes and Active Tectonics, Institut Teknologi Bandung, Bandung; Widiyantoro, Sri

East Java has a fairly complex geological structure. Physiographically East Java can be divided into three zones, i.e. the Southern Mountains zone in the southern part, the Kendeng zone in the middle part, and the Rembang zone in the northern part. Most of the seismic hazards in this region are due to processes in the upper crust. In this study, the Ambient Noise Tomography (ANT) method is used to image the upper crustal structure beneath East Java. We have used seismic waveform data recorded by 8Meteorological, Climatological and Geophysical Agency (BMKG) stationary seismographic stations and 16 portable seismographs installed formore » 2 to 8 weeks. The data were processed to obtain waveforms fromnoise cross-correlation between pairs of seismographic stations. Our preliminary results indicate that the Kendeng zone, an area of low gravity anomaly, is associated with a low velocity zone. On the other hand, the southern mountain range, which has a high gravity anomaly, is related to a high velocity anomaly as shown by our tomographic images.« less

Hydrogeology, water quality, and water-supply potential of the Lower Floridan Aquifer, coastal Georgia, 1999-2002

USGS Publications Warehouse

Falls, W. Fred; Harrelson, Larry G.; Conlon, Kevin J.; Petkewich, Matthew D.

2005-01-01

The hydrogeology and water quality of the upper permeable and Fernandina permeable zones of the Lower Floridan aquifer were studied at seven sites in the 24-county study area encompassed by the Georgia Coastal Sound Science Initiative. Although substantially less than the Upper Floridan aquifer in coastal Georgia, transmissivities for the Lower Floridan aquifer are in the same range as other water-supply aquifers in Georgia and South Carolina and could meet the needs of public drinking-water supply. Water of the upper permeable zone of the Lower Floridan aquifer exceeds the Federal secondary drinking-water standards for sulfate and total dissolved solids at most coastal Georgia sites and the Federal secondary drinking-water standard for chloride at the Shellman Bluff site. The top of the Lower Floridan aquifer correlates within 50 feet of the previously reported top, except at the St Simons Island site where the top is more than 80 feet higher. Based on the hydrogeologic characteristics, the seven sites are divided into the northern sites at Shellman Bluff, Richmond Hill, Pembroke, and Pineora; and southern sites at St Marys, Brunswick, and St Simons Island. At the northern sites, the Lower Floridan aquifer does not include the Fernandina permeable zone, is thinner than the overlying Upper Floridan aquifer, and consists of only strata of the middle Eocene Avon Park Formation. Transmissivities in the Lower Floridan aquifer are 8,300 feet squared per day at Richmond Hill and 6,000 feet squared per day at Shellman Bluff, generally one tenth the transmissivity of the Upper Floridan aquifer at these sites. At the southern sites, the upper permeable zone of the Lower Floridan aquifer is thicker than the Upper Floridan aquifer and consists of porous limestone and dolomite interbedded with nonporous strata of the middle Eocene Avon Park and early Eocene Oldsmar Formations. Transmissivities for the upper permeable zone of the Lower Floridan aquifer are 500 feet squared per day at the St Simons Island site and 13,000 feet squared per day at the St Marys site. The Lower Floridan aquifer at the Brunswick and St Marys sites includes the Fernandina permeable zone, which consists of saltwater-bearing dolomite. Hydrographs of Coastal Sound Science Initiative wells and other nearby wells open to the Upper Floridan aquifer, and the upper permeable and Fernandina permeable zones of the Lower Floridan aquifer have similar trends. Water levels in wells open to the Upper and Lower Floridan aquifers are below land surface at the northern sites and the St Simons Island site, and above land surface at the Brunswick and St Marys sites, as of January 1, 2004. Freshwater is present in the Lower Floridan aquifer at Pineora, Pembroke, and St Marys, and from 1,259 to 1,648 feet below land surface at Brunswick. Slightly saline water is present in the Lower Floridan aquifer at Richmond Hill, Shellman Bluff, St Simons Island, and from 1,679 to 1,970 feet below land surface in well 34H495 at Brunswick. The upper permeable zone of the Lower Floridan aquifer contains bicarbonate water at the Pembroke site, sulfate-bicarbonate water at the Brunswick site, and sulfate water at the St Simons Island, Shellman Bluff, St Marys, and Richmond Hill sites. The bicarbonate, sulfate-bicarbonate, and sulfate waters are saturated relative to calcite and dolomite, and undersaturated with gypsum and anhydrite. The Fernandina permeable zone in well 34H495 includes moderately saline water, very saline water, and brine. The Fernandina permeable zone of the Lower Floridan aquifer beneath downtown Brunswick contains chloride water that is slightly undersaturated to saturated with gypsum and anhydrite. Concentrations of total dissolved solids, sulfate, and chloride exceeded the Federal secondary drinking-water standards. The chloride-contaminated plumes beneath downtown Brunswick would require at least a 12- to 20-percent contribution of very saline water from the Fernandi

Imaging the crustal magma sources beneath Mauna Loa and Kilauea volcanoes, Hawaii

USGS Publications Warehouse

Okubo, Paul G.; Benz, Harley M.; Chouet, Bernard A.

1997-01-01

Three-dimensional seismic P-wave traveltime tomography is used to image the magma sources beneath Mauna Loa and Kilauea volcanoes, Hawaii. High-velocity bodies (>6.4 km/s) in the upper 9 km of the crust beneath the summits and rift zones of the volcanoes correlate with zones of high magnetic intensities and are interpreted as solidified gabbro-ultramafic cumulates from which the surface volcanism is derived. The proximity of these high-velocity features to the rift zones is consistent with a ridge-spreading model of the volcanic flank. Southeast of the Hilina fault zone, along the south flank of Kilauea, low-velocity material (<6.0 km/s) is observed extending to depths of 9–11 km, indicating that the Hilina fault may extend possibly as deep as the basal decollement. Along the southeast flank of Mauna Loa, a similar low-velocity zone associated with the Kaoiki fault zone is observed extending to depths of 6–8 km. These two upper crustal low-velocity zones suggest common stages in the evolution of the Hawaiian shield volcanoes in which these fault systems are formed as a result of upper crustal deformation in response to magma injection within the volcanic edifice.

High Altitude Balloon Flight Path Prediction and Site Selection Based On Computer Simulations

NASA Astrophysics Data System (ADS)

Linford, Joel

2010-10-01

Interested in the upper atmosphere, Weber State University Physics department has developed a High Altitude Reconnaissance Balloon for Outreach and Research team, also known as HARBOR. HARBOR enables Weber State University to take a variety of measurements from ground level to altitudes as high as 100,000 feet. The flight paths of these balloons can extend as long as 100 miles from the launch zone, making the choice of where and when to fly critical. To ensure the ability to recover the packages in a reasonable amount of time, days and times are carefully selected using computer simulations limiting flight tracks to approximately 40 miles from the launch zone. The computer simulations take atmospheric data collected by National Oceanic and Atmospheric Administration (NOAA) to plot what flights might have looked like in the past, and to predict future flights. Using these simulations a launch zone has been selected in Duchesne Utah, which has hosted eight successful flights over the course of the last three years, all of which have been recovered. Several secondary launch zones in western Wyoming, Southern Idaho, and Northern Utah are also being considered.

Uppermost oceanic crust structure and properties from multichannel seismic data at the Alaska subduction zone

NASA Astrophysics Data System (ADS)

Becel, A.; Carton, H. D.; Shillington, D. J.

2017-12-01

The most heterogeneous, porous and permeable layer within a subducting oceanic crust is the uppermost layer called Layer 2A. This layer, made of extrusive basalts, forms at the ridge axis and persists as a thin ( 600 m) low-velocity cap in old crust. Nearing the trench axis, when oceanic plate bends, normal faults can be formed or reactivated at the outer-rise allowing a more vigorous hydrothermal circulation to resume within this layer. Porosity and heterogeneity within this layer are important to assess because these parameters might have a profound impact on subduction zone processes. However, conventional refraction data quality is rarely good enough to look into detail into the properties of the uppermost oceanic layer. Here we use 2D marine long-offset multi-channel seismic (MCS) reflection data collected offshore of the Alaska Peninsula during the ALEUT Program. The dataset was acquired aboard the R/V Marcus Langseth with a 636-channels, 8-km long streamer. We present initial results from three 140 km long profiles across the 52-56Myr old incoming Pacific oceanic crust formed at fast spreading rate: two perpendicular margin and one parallel margin profiles. Those profiles are located outboard of the Shumagin gaps. Outboard of this subduction zone segment, abundant bending related normal faults are imaged and concentrated within 50-60 km of the trench. Long-offset MCS data exhibit a prominent triplication that includes postcritical reflections and turning waves within the upper crust at offsets larger than 3 km. The triplication suggests the presence of a velocity discontinuity within the upper oceanic crust. We follow a systematic and uniform approach to extract upper crustal post-critical reflections and add them to them to the vertical incidence MCS images. Images reveal small-scale variations in the thickness of the Layer 2A and the strength of its base along the profiles. The second step consists of the downward continuation followed by travel-time modeling of the long streamer data. The downward continuation of the shots and receivers appears to be essential to unravel the refracted energy in the upper crust and is used to determine the detailed velocity-depth structure.

Revisiting concepts of thermal physiology: Predicting responses of mammals to climate change.

PubMed

Mitchell, Duncan; Snelling, Edward P; Hetem, Robyn S; Maloney, Shane K; Strauss, Willem Maartin; Fuller, Andrea

2018-02-26

The accuracy of predictive models (also known as mechanistic or causal models) of animal responses to climate change depends on properly incorporating the principles of heat transfer and thermoregulation into those models. Regrettably, proper incorporation of these principles is not always evident. We have revisited the relevant principles of thermal physiology and analysed how they have been applied in predictive models of large mammals, which are particularly vulnerable, to climate change. We considered dry heat exchange, evaporative heat transfer, the thermoneutral zone and homeothermy, and we examined the roles of size and shape in the thermal physiology of large mammals. We report on the following misconceptions in influential predictive models: underestimation of the role of radiant heat transfer, misassignment of the role and misunderstanding of the sustainability of evaporative cooling, misinterpretation of the thermoneutral zone as a zone of thermal tolerance or as a zone of sustainable energetics, confusion of upper critical temperature and critical thermal maximum, overestimation of the metabolic energy cost of evaporative cooling, failure to appreciate that the current advantages of size and shape will become disadvantageous as climate change advances, misassumptions about skin temperature and, lastly, misconceptions about the relationship between body core temperature and its variability with body mass in large mammals. Not all misconceptions invalidate the models, but we believe that preventing inappropriate assumptions from propagating will improve model accuracy, especially as models progress beyond their current typically static format to include genetic and epigenetic adaptation that can result in phenotypic plasticity. © 2018 The Authors. Journal of Animal Ecology © 2018 British Ecological Society.

Can compliant fault zones be used to measure absolute stresses in the upper crust?

NASA Astrophysics Data System (ADS)

Hearn, E. H.; Fialko, Y.

2009-04-01

Geodetic and seismic observations reveal long-lived zones with reduced elastic moduli along active crustal faults. These fault zones localize strain from nearby earthquakes, consistent with the response of a compliant, elastic layer. Fault zone trapped wave studies documented a small reduction in P and S wave velocities along the Johnson Valley Fault caused by the 1999 Hector Mine earthquake. This reduction presumably perturbed a permanent compliant structure associated with the fault. The inferred changes in the fault zone compliance may produce a measurable deformation in response to background (tectonic) stresses. This deformation should have the same sense as the background stress, rather than the coseismic stress change. Here we investigate how the observed deformation of compliant zones in the Mojave Desert can be used to constrain the fault zone structure and stresses in the upper crust. We find that gravitational contraction of the coseismically softened zones should cause centimeters of coseismic subsidence of both the compliant zones and the surrounding region, unless the compliant fault zones are shallow and narrow, or essentially incompressible. We prefer the latter interpretation because profiles of line of sight displacements across compliant zones cannot be fit by a narrow, shallow compliant zone. Strain of the Camp Rock and Pinto Mountain fault zones during the Hector Mine and Landers earthquakes suggests that background deviatoric stresses are broadly consistent with Mohr-Coulomb theory in the Mojave upper crust (with μ ≥ 0.7). Large uncertainties in Mojave compliant zone properties and geometry preclude more precise estimates of crustal stresses in this region. With improved imaging of the geometry and elastic properties of compliant zones, and with precise measurements of their strain in response to future earthquakes, the modeling approach we describe here may eventually provide robust estimates of absolute crustal stress.

The Shift of Thermoneutral Zone in Striped Hamster Acclimated to Different Temperatures

PubMed Central

Zhao, Zhi-Jun; Chi, Qing-Sheng; Liu, Quan-Sheng; Zheng, Wei-Hong; Liu, Jin-Song; Wang, De-Hua

2014-01-01

Temperature affects all biological functions and will therefore modulate ecologically significant interactions between animals and their environment. Here, we examined the effect of ambient temperature (Ta) on the thermal biology and energy budget in striped hamsters acclimated to cold (5°C), warm (21°C) and hot temperatures (31°C). Thermoneutral zone (TNZ) was 22.5–32.5°C, 25–32.5°C and 30–32.5°C in the cold-, warm- and hot-acclimated hamsters, respectively. The cold acclimation decreased the lower critical temperature and made the TNZ wider, and hot exposure elevated the lower critical temperature, resulting in a narrow TNZ. Within the TNZ, cold-acclimated hamsters showed a significantly higher rate of metabolism and thermogenesis than those acclimated to hot temperature. Digestive enzymes activities, including intestinal sucrase, maltase, L-alanine aminopeptidase-N and leucine aminopeptidase were higher in the cold than in the hot. The changes in metabolic rate and thermogenesis at different temperatures were in parallel with cytochrome c oxidase activity and uncoupling protein 1 gene expression of brown adipose tissue. This suggests that the shift of the lower critical temperature of TNZ is possibly associated with the rate of metabolism and thermogenesis, as well as with the digestive capacity of the gastrointestinal tract at different Ta. The upper critical temperature of TNZ may be independent of the changes in Ta. The changes of lower critical temperature of TNZ are an important strategy in adaption to variations of Ta. PMID:24400087

78 FR 74009 - Safety Zone; Nike Fireworks, Upper New York Bay, Ellis Island, NY

Federal Register 2010, 2011, 2012, 2013, 2014

2013-12-10

... DEPARTMENT OF HOMELAND SECURITY Coast Guard 33 CFR Part 165 [Docket No. USCG-2013-0962] Safety Zone; Nike Fireworks, Upper New York Bay, Ellis Island, NY AGENCY: Coast Guard, DHS. ACTION: Notice of... published in the Federal Register on November 9, 2011 (76 FR 69614). [[Page 74010

Evolution of crustal stress, pressure and temperature around shear zones during orogenic wedge formation: a 2D thermo-mechanical numerical study

NASA Astrophysics Data System (ADS)

Markus Schmalholz, Stefan; Jaquet, Yoann

2016-04-01

We study the formation of an orogenic wedge during lithospheric shortening with 2D numerical simulations. We consider a viscoelastoplastic rheology, thermo-mechanical coupling by shear heating and temperature-dependent viscosities, gravity and erosion. In the initial model configuration there is either a lateral temperature variation at the model base or a lateral variation in crustal thickness to generate slight stress variations during lithospheric shortening. These stress variations can trigger the formation of shear zones which are caused by thermal softening associated with shear heating. We do not apply any kind of strain softening, such as reduction of friction angle with progressive plastic strain. The first major shear zone that appears during shortening crosscuts the entire crust and initiates the asymmetric subduction/underthrusting of mainly the mechanically strong lower crust. After some deformation, the first shear zone in the upper crust is abandoned, the deformation propagates towards the foreland and a new shear zone forms only in the upper crust. The shear zone propagation occurs several times where new shear zones form in the upper crust and the mechanically strong top of the lower crust acts as detachment horizon. We calculate the magnitudes of the maximal and minimal principal stresses and of the mean stress (or dynamic pressure), and we record also the temperature for several marker points in the upper and lower crust. We analyse the evolution of stresses and temperature with burial depth and time. Deviatoric stresses (half the differential stress) in the upper crust are up to 200 MPa and associated shear heating in shear zones ranges between 40 - 80 °C. Lower crustal rocks remain either at the base of the orogenic wedge at depths of around 50 km or are subducted to depths of up to 120 km, depending on their position when the first shear zone formed. Largest deviatotric stresses in the strong part of the lower crust are about 1000 MPa and maximal shear heating in shear zones is approximately 200 °C. Marker points can migrate through the main shear zone in the lower crust which remains active throughout lithospheric shortening. Some pressure-temperature paths show an anti-clockwise evolution. The impact of various model parameters on the results is discussed as well as applications of the results to geological data.

Vesicular komatiites, 3.5-Ga Komati Formation, Barberton Greenstone Belt, South Africa: inflation of submarine lavas and origin of spinifex zones

NASA Astrophysics Data System (ADS)

Dann, Jesse

2001-08-01

Komatiites of the 3.5-Ga Komati Formation are ultramafic lavas (>23% MgO) erupted in a submarine, lava plain environment. Newly discovered vesicular komatiites have vesicular upper crusts disrupted by synvolcanic structures that are similar to inflation-related structures of modern lava flows. Detailed outcrop maps reveal flows with upper vesicular zones, 2-15 m thick, which were (1) rotated by differential inflation, (2) intruded by dikes from the interior of the flow, (3) extended, forming a flooded graben, and/or (4) entirely engulfed. The largest inflated structure is a tumulus with 20 m of surface relief, which was covered by a compound flow unit of spinifex flow lobes. The lava that inflated and rotated the upper vesicular crust did not vesiculate, but crystallized as a thick spinifex zone with fist-size skeletal olivine. Instead of representing rapidly cooled lava, the spinifex zone cooled slowly beneath an insulating upper crust during inflation. Overpressure of the inflating lava may have inhibited vesiculation. This work describes the oldest vesicular komatiites known, illustrates the first field evidence for inflated structures in komatiite flows, proposes a new factor in the development of spinifex zones, and concludes that the inflation model is useful for understanding the evolution of komatiite submarine flow fields.

Trace fossils and sedimentology of a Late Cretaceous Progradational Barrier Island sequence: Bearpaw and Horseshoe Canyon Formations, Dorothy, Alberta

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

Saunders, T.D.; Pemberton, A.G.; Ranger, M.J.

A well-exposed example of a regressive barrier island succession crops out in the Alberta badlands along the Red Deer River Valley. In the most landward (northwestern) corner of the study area, only shallow-water and subaerial deposits are represented and are dominated by tidal inlet related facies. Seaward (southeast), water depth increases and the succession is typified by open-marine beach to offshore-related facies arranged in coarsening-upward progradational sequence. Detailed sedimentologic and ichnologic analyses of this sequence have allowed for its division into three distinct environmental zones (lower, middle, and upper). The lower zone comprises a laterally diverse assemblage of storm-influenced, lowermore » shoreface through offshore deposits. Outcrop in the northeast is dominated by thick beds of hummocky and/or swaley cross-stratified storm sand. In the southeast, storm events have only minor influence. This lower zone contains a wide diversity of well-preserved trace fossils whose distribution appears to have been influenced by gradients in wave energy, bottom stagnation, and the interplay of storm and fair-weather processes. The middle zone records deposition across an upper shoreface environment. Here, horizontal to low-angle bedding predominates, with interspersed sets of small- and large-scale cross-bedding increasing toward the top. A characteristic feature of the upper part of this zone is the lack of biogenic structures suggesting deposition in an exposed high-energy surf zone. The upper zone records intertidal to supratidal progradation of the shoreline complex. Planar-laminated sandstone forms a distinct foreshore interval above which rhizoliths and organic material become increasingly abundant, marking transition to the backshore. A significant feature of this zone is the occurrence of an intensely bioturbated interval toward the top of the foreshore.« less

Emplacement model of obsidian-rhyolite magma deduced from complete internal section of the Akaishiyama lava, Shirataki, northern Hokkaido, Japan

NASA Astrophysics Data System (ADS)

Wada, K.; Sano, K.

2016-12-01

Simultaneously explosive and effusive eruptions of silicic magmas has shed light on the vesiculation and outgassing history of ascending magmas in the conduit and emplacement model of obsidian-rhyolite lavas (Castro et al., 2014; Shipper et al, 2013). As well as the knowledge of newly erupted products such as 2008-2009 Chaitén and 2011-2012 Cordón Caule eruptions, field and micro-textural evidences of well-exposed internal structure of obsidian-rhyolite lava leads to reveal eruption processes of silicic magmas. The Shirataki monogenetic volcano field, 2.2 million year age, northern Hokkaido, Japan, contains many outcrops of obsidian and vesiculated rhyolite zones (SiO2=76.7-77.4 wt.%). Among their outcrops, Akaishiyama lava shows good exposures of internal sections from the top to the bottom along the Kyukasawa valley with thickness of about 190 meters, showing the symmetrical structure comprising a upper clastic zone (UCZ; 5m thick), an upper dense obsidian zone (UDO; 15m), an upper banded obsidian zone (UBO; 70-80m), a central rhyolite zone (CR; 65m), a lower banded obsidian zone (LBO; 15m), a lower dense obsidian zone (LDO; 20m), and a lower clastic zone (LCZ; 3m). The upper banded obsidian zone is characterized by existence of spherulite concentration layers with tuffisite veins and rhyolite enclaves. Spherulites consisting of albite, cristobalaite and obsidian glass, are clustered in the dense obsidian. Tuffisite veins show brecciated obsidians in tuffaceous matrix, showing an outgassing path during the emplacement of obsidian lava. Perpendicular dip of spherulite parallel rows indicates the banded zone itself was the domain of vent area. From the observation of these occurrences in the internal section and rock texture, we show the qualitative formation model of Shirataki obsidian-rhyolite lava.

An arthroscopic evaluation of the anatomical "critical zone".

PubMed

Naidoo, N; Lazarus, L; Osman, S A; Satyapal, K S

2017-01-01

The "critical zone", a region of speculated vascularity, is situated approximately 10 mm proximal to the insertion of the supraspinatus tendon. Despite its obvious role as an anatomical landmark demarcator, its patho-anatomic nature has been identified as the source of rotator cuff pathology. Although many studies have attempted to evaluate the vascularity of this region, the architecture regarding the exact length, width and shape of the critical zone, remains unreported. This study aimed to determine the shape and morphometry of the "critical zone" arthroscopically. The sample series, which was comprised of 38 cases (n = 38) specific to pathological types, employed an anatomical investigation of the critical zone during routine real-time arthroscopy. Demographic representation: i) sex: 19 males, 19 females; ii) age range: 18-76 years; iii) race: white (n = 29), Indian (n = 7) and coloured (n = 2). The incidence of shape and the mean lengths and widths of the critical zone were determined in accordance with the relevant demographic factors and patient history. Although the cresenteric shape was predominant, hemispheric and sail-shaped critical zones were also identified. The lengths and widths of the critical zone appeared markedly increased in male individuals. While the increase in age may account for the increased incidence of rotator cuff degeneration due to poor end-vascular supply, the additional factors of height and weight presented as major determinants of the increase in size of the critical zone. In addition, the comparisons of length and width with each other and shape yielded levels of significant difference, therefore indicating a directly proportional relationship between the length and width of the critical zone. This detailed understanding of the critical zone may prove beneficial for the success of post-operative rotator cuff healing.

Critical zone properties control the fate of nitrogen during experimental rainfall in montane forests of the Colorado Front Range

USGS Publications Warehouse

Hinckley, Eve-Lyn S.; Ebel, Brian A.; Barnes, Rebecca T.; Murphy, Sheila F.; Anderson, Suzanne P.

2017-01-01

Several decades of research in alpine ecosystems have demonstrated links among the critical zone, hydrologic response, and the fate of elevated atmospheric nitrogen (N) deposition. Less research has occurred in mid-elevation forests, which may be important for retaining atmospheric N deposition. To explore the fate of N in the montane zone, we conducted plot-scale experimental rainfall events across a north–south transect within a catchment of the Boulder Creek Critical Zone Observatory. Rainfall events mimicked relatively common storms (20–50% annual exceedance probability) and were labeled with 15N-nitrate (NO3−">NO−3NO3−) and lithium bromide tracers. For 4 weeks, we measured soil–water and leachate concentrations of Br−, 15NO3−,">15NO−3,15NO3−, and NO3−">NO−3NO3− daily, followed by recoveries of 15N species in bulk soils and microbial biomass. Tracers moved immediately into the subsurface of north-facing slope plots, exhibiting breakthrough at 10 and 30 cm over 22 days. Conversely, little transport of Br− or 15NO3−">15NO−315NO3− occurred in south-facing slope plots; tracers remained in soil or were lost via pathways not measured. Hillslope position was a significant determinant of soil 15N-NO3−">NO−3NO3− recoveries, while soil depth and time were significant determinants of 15N recovery in microbial biomass. Overall, 15N recovery in microbial biomass and leachate was greater in upper north-facing slope plots than lower north-facing (toeslope) and both south-facing slope plots in August; by October, 15N recovery in microbial N biomass within south-facing slope plots had increased substantially. Our results point to the importance of soil properties in controlling the fate of N in mid-elevation forests during the summer season.

Weathering, Fractures and Water in the deep Critical Zone: Geophysical investigations in the U.S. Critical Zone Observatories

NASA Astrophysics Data System (ADS)

Holbrook, W. S.; Carr, B.; Moon, S.; Perron, J. T.; Hayes, J. L.; Flinchum, B. A.; St Clair, J. T.; Riebe, C. S.; Richter, D., Jr.; Leone, J.

2015-12-01

The Critical Zone (CZ) is Earth's breathing skin: the thin layer from treetop to bedrock that supports most terrestrial life. Key hydrological, biogeochemical, and physical processes occur in the CZ, including physical and chemical weathering, soil production, erosion, nutrient cycling, and surface/groundwater exchange. These processes in turn influence subsurface water storage capacity, landscape evolution, ecological stability, aquifer recharge and stream flow. Because the deep CZ is hidden from direct observation, it can only be studied by drilling and/or geophysical measurements. Given the relative scarcity of such data, we lack a complete understanding of the architecture of the CZ, how it varies across landscapes, and what controls that variation. We present geophysical data that address these questions at six Critical Zone Observatories (CZO): Calhoun, Boulder Creek, Eel River, Reynolds Creek, Catalina-Jemez, and Southern Sierra. Conclusions include: (1) Regolith depth is influenced by the opening of fractures due to the release of regional and topographic stress as rocks are exhumed toward the surface. Stress models at Calhoun and Boulder Creek show remarkable agreement with seismic velocities in the shallow subsurface, suggesting that stress release controls the development of fracture porosity in the CZ. (2) Chemical weathering (plagioclase dissolution) begins at depths where fractures open (~40 m at Calhoun), implying that fracturing and chemical weathering are intimately paired in the deep CZ. (3) Volumetric strain is an underappreciated contributor to porosity in the CZ. In the Southern Sierra, strain dominates over chemical weathering in the upper 10 m, consistent with the stress-release model. (4) Geological structure and lithology can trump environmental controls (e.g., aspect and climate) on regolith development. At Catalina, strongly contrasting regolith thickness on north- and south-facing slopes, is not due to "northness", but rather to foliation in the schist bedrock, which dips into the south-facing slope, creating permeable pathways for water infiltration. Lithology, especially differences in initial porosity, strongly influences regolith thickness at Reynolds Creek, where regolith is thicker in basalt flows than in granite.

Patterns in Soil Electrical Resistivity Across Land Uses in the Calhoun Critical Zone Observatory Landscape

NASA Astrophysics Data System (ADS)

Markewitz, D.; Sutter, L.; Richter, D. D., Jr.

2017-12-01

Soil Electrical Resistivity Tomography (ERT) was measured across the Calhoun Critical Zone Observatory in relation to land use cover. ERT can help identify patterns in soil and saprolite physical attributes and moisture content through multiple meters. ERT data were generated with an AGI Supersting R8 with a 28 probe dipole-dipole array on a 1.5 meter spacing providing information through the upper 9 m. In Nov/Dec 2016 ten soil pits were dug to 3m depth in agricultural fields, pine forests, and hardwood forests across the CCZO and ERT measures were taken centered on these pits. ERT values ranged from 200 to 2500 Ohm-m. ERT patterns in the agricultural field demonstrated a limited resistivity gradient (200-700 Ohm-m) appearing moist throughout. In contrast, research areas under pine and hardwood forest had stronger resistivity gradients reflecting both moisture and physical attributes (i.e., texture or rock content). For example, research area 2 under pine had an area of higher resistivity that correlated with a band of saprolite that was readily visible in the exposed profile. In research area 7 and 8 that included both pine and hardwood forest resistivity gradients had contradictory patterns of high to low resistivity from top to bottom. In research area 7 resistivity was highest at the surface and decreased with depth, a common pattern when water table is at depth. In research area 8 the inverse was observed with low resistivity above and resistivity increasing with depth, a pattern observed in upper landscape positions on ridges with moist clay above dry saprolite. ERT patterns did reflect a large difference in the measured agricultural fields compared to forest while other difference appeared to reflect landscape position.

Tethyan calpionellids in the Neuquén Basin (Argentine Andes), their significance in defining the Jurassic/Cretaceous boundary and pathways for Tethyan-Eastern Pacific connections

NASA Astrophysics Data System (ADS)

López-Martínez, Rafael; Aguirre-Urreta, Beatriz; Lescano, Marina; Concheyro, Andrea; Vennari, Verónica; Ramos, Victor A.

2017-10-01

The study of calpionellid distribution in the well-documented Las Loicas section of the Vaca Muerta Formation in the Neuquén Basin, Argentine Andes, allows the recognition of the upper part of the Crassicollaria Zone and the lower part of Calpionella Zone across the Jurassic/Cretaceous boundary. The Crassicollaria Zone, Colomi Subzone (Upper Tithonian) is composed of Calpionella alpina Lorenz, Crassicollaria colomi Doben, Crassicollaria parvula Remane, Crassicollaria massutiniana (Colom), Crassicollaria brevis Remane, Tintinnopsella remanei (Borza) and Tintinnopsella carpathica (Murgeanu and Filipescu). The Calpionella Zone, Alpina Subzone (Lower Berriasian) is indicated by the explosion of the small and globular form of Calpionella alpina dominating over very scarce Crassicollaria massutiniana. The FAD of Nannoconus wintereri can be clearly correlated with the upper part of Crassicollaria Zone and the FAD of Nannoconus kamptneri minor with the Calpionella Zone. Additional studies are necessary to establish a more detailed calpionellid biozonation and its correlation with other fossil groups. The present work confirms similar calpionellid bioevents in westernmost Tethys (Cuba and Mexico) and the Andean region, strengthening the Paleo-Pacific-Tethyan connections through the Hispanic Corridor already known from other fossil groups.

Space–time mapping of wasting among children under the age of five years in Somalia from 2007 to 2010

PubMed Central

Kinyoki, Damaris K; Berkley, James A; Moloney, Grainne M; Odundo, Elijah O; Kandala, Ngianga-Bakwin; Noor, Abdisalan M

2016-01-01

Objective To determine the sub-national seasonal prevalence and trends in wasting from 2007 to 2010 among children aged 6–59 months in Somalia using remote sensing and household survey data from nutritional surveys. Methods Bayesian hierarchical space–time model was implemented using a stochastic partial differential equation (SPDE) approach in integrated nested Laplace approximations (INLA) to produce risk maps of wasting at 1 × 1 km2 spatial resolution and predict to seasons in each year of study from 2007 to 2010. Results The prevalence of wasting was generally at critical levels throughout the country, with most of the areas remaining in the upper classes of critical and very critical levels. There was minimal variation in wasting from year-to-year, but a well-defined seasonal variation was observed. The mean difference of the prevalence of wasting between the dry and wet season ranges from 0% to 5%. The risks of wasting in the South Central zone were highest in the Gedo (37%) and Bay (32%) regions. In North East zone the risk was highest in Nugaal (25%) and in the North West zone the risk was high in Awdal and Woqooyi Galbeed regions with 23%. Conclusion There was a clear seasonal variation in wasting with minimal year-to-year variability from 2007 to 2010 in Somalia. The prevalence was high during the long dry season, which affects the prevalence in the preceding long rainy season. Understanding the seasonal fluctuations of wasting in different locations and at different times is important to inform timely interventions. PMID:26919757

Lithologic Controls on Critical Zone Processes in a Variably Metamorphosed Shale-Hosted Watershed

NASA Astrophysics Data System (ADS)

Eldam Pommer, R.; Navarre-Sitchler, A.

2017-12-01

Local and regional shifts in thermal maturity within sedimentary shale systems impart significant variation in chemical and physical rock properties, such as pore-network morphology, mineralogy, organic carbon content, and solute release potential. Even slight variations in these properties on a watershed scale can strongly impact surface and shallow subsurface processes that drive soil formation, landscape evolution, and bioavailability of nutrients. Our ability to map and quantify the effects of this heterogeneity on critical zone processes is hindered by the complex coupling of the multi-scale nature of rock properties, geochemical signatures, and hydrological processes. This study addresses each of these complexities by synthesizing chemical and physical characteristics of variably metamorphosed shales in order to link rock heterogeneity with modern earth surface and shallow subsurface processes. More than 80 samples of variably metamorphosed Mancos Shale were collected in the East River Valley, Colorado, a headwater catchment of the Upper Colorado River Basin. Chemical and physical analyses of the samples show that metamorphism decreases overall rock porosity, pore anisotropy, and surface area, and introduces unique chemical signatures. All of these changes result in lower overall solute release from the Mancos Shale in laboratory dissolution experiments and a change in rock-derived solute chemistry with decreasing organic carbon and cation exchange capacity (Ca, Na, Mg, and K). The increase in rock competency and decrease in reactivity of the more thermally mature shales appear to subsequently control river morphology, with lower channel sinuosity associated with areas of the catchment underlain by metamorphosed Mancos Shale. This work illustrates the formative role of the geologic template on critical zone processes and landscape development within and across watersheds.

The Critical Zone: A Necessary Framework for Understanding Surface Earth Processes

NASA Astrophysics Data System (ADS)

Dietrich, W. E.

2016-12-01

One definition of the critical zone is: the thin veneer of Earth that extends from the top of the vegetation to the base of weathered bedrock. With this definition we can envision the critical zone as a distinct entity with a well-defined top and a fairly well-defined bottom that is distributed across terrestrial earth landscapes. It is a zone of co-evolving processes and, importantly, much of this zone is well below the soil mantle (and commonly more than 10 times thicker than the soil). Weathering advance into fresh bedrock creates a hydrologically-conductive skin that mediates runoff and solute chemistry, stores water used by vegetation, releases water as baseflow to streams, influences soil production and hillslope evolution, and feeds gasses to the atmosphere. Especially in seasonally dry environments, rock moisture in the critical zone, i.e. moisture that is exchangeable and potentially mobile in the matrix and fractures of the bedrock, can be a significant source of water to plants and is a previously unrecognized large component of the water budget that matters to climate models. First observations on the systematic variation of the critical zone across hillslopes have led to four distinct theories representing four distinct processes for what controls the depth to fresh bedrock (and thus the thickness of this zone across a hillslope). These theories are motivating geophysical surveys, deep drilling, and other actions to parameterize and explore the power of these models. Studies at the NSF-supported Critical Zone Observatories have taught us that the critical zone is an entity and that enduring field studies reveal key processes. A challenge we now face is how to include this emerging understanding of the critical zone into models of reactive transport, hydrologic processes and water supply, critical zone structure, landscape evolution, and climate.

Geohydrology and evaluation of water-resource potential of the upper Floridan Aquifer in the Albany area, southwestern Georgia

USGS Publications Warehouse

Torak, L.J.; Davis, G.S.; Strain, G.A.; Herndon, J.G.

1993-01-01

In the Albany area of southwestern Georgia, the Upper Floridan aquifer lies entirely within the Dougherty Plain district of the Coastal Plain physiographic province, and consists of the Ocala Limestone of late Eocene age. The aquifer is divided throughout most of the study area into an upper and a lower lithologic unit, which creates an upper and a lower water-bearing zone. The lower waterbearing zone consists of alternating layers of sandy limestone and medium-brown, recrystallized dolomitic limestone, and ranges in thickness from about 50 ft to 100 ft. It is highly fractured and exhibits well-developed permeability by solution features that are responsible for transmitting most of the ground water in the aquifer. Transmissivity of the lower water-bearing zone ranges from about 90,000 to 178,000 ft2/d. The upper water-bearing zone is a finely crystallized-to-oolitic, locally dolomitic limestone having an average thickness of about 60 ft. Transmissivities are considerably less in the upper water-bearing zone than in the lower water-bearing zone. The Upper Floridan aquifer is overlain by about 20-120 ft of undifferentiated overburden consisting of fine-to-coarse quartz sand and noncalcareous clay. A clay zone about 10-30 ft thick may be continuous throughout the southwestern part of the Albany area and, where present, causes confinement of the Upper Floridan aquifer and creates perched ground water after periods of heavy rainfall. The Upper Floridan aquifer is confined below by the Lisbon Formation, a mostly dolomitic limestone that contains trace amounts of glauconite. The Lisbon Formation is at least 50 ft thick in the study area and acts as an impermeable base to the Upper Floridan aquifer. The quality of ground water in the Upper Floridan aquifer is suitable for most uses; wells generally yield water of the hard, calcium-bicarbonate type that meets the U.S. Environmental Protection Agency's Primary or Secondary Drinking-Water Regulations. The water-resource potential of the Upper Floridan aquifer was evaluated by compiling results of drilling and aquifer testing in the study area, and by conducting computer simulations of the ground-water flow system under the seasonally low conditions of November 1985, and under conditions of pumping within a 12-mi 2 area located southwest of Albany. Results of test drilling, aquifer testing, and water-quality analyses indicate that, in the area southwest of Albany, geohydrologic conditions in the Upper Floridan aquifer, undifferentiated overburden, and Lisbon Formation were favorable for the aquifer to provide a large quantity of water without having adverse effects on the groundwater system. The confinement of the Upper Floridan aquifer by the undifferentiated overburden and the rural setting of the area of potential development decrease the likelihood that chemical constituents will enter the aquifer during development of the ground-water resources. Computer simulations of ground-water flow in the Upper Floridan aquifer, incorporating conditions for regional flow across model boundaries, leakage from rivers and other surface-water features, and vertical leakage from the undifferentiated overburden, were conducted by using a finite-element model for ground-water flow in two dimensions. Comparison of computed and measured water levels in the Upper Floridan aquifer for November 1985 at 74 locations indicated that computed water levels generally were within 5 ft of the measured values, which is the accuracy to which measured water levels were known. Water-level altitudes ranged from about 260 ft to 130 ft above sea level in the study area during calibration. Aquifer discharge to the Flint River downstream from the Lake Worth dam was computed by the calibrated model to be about 1 billion gallons per day; about 300 million gallons per day (Mgal/d) greater than was measured for similar lowflow conditions. The excess computed discharge was attributed partially to stream withdrawals for

Meiofauna as descriptor of tourism-induced changes at sandy beaches.

PubMed

Gheskiere, Tom; Vincx, Magda; Weslawski, Jan Marcin; Scapini, Felicita; Degraer, Steven

2005-08-01

Tourism has long been considered as a 'clean industry' with almost no negative effects on the environment. This study demonstrated, in two different coastal systems (Mediterranean and Baltic), that tourism related activities are particularly affecting the sandy beach meio- and nematofauna in the upper beach zone, the specific ecotone in which many meiofauna species from both the marine and the terrestrial environment congregate. Tourist upper beaches are characterized by a lower % total organic matter (%TOM), lower densities, lower diversities (absence of Insecta, Harpacticoida, Oligochaeta, terrestrial nematodes and marine Ironidae nematodes) and higher community stress compared to nearby non-tourist locations. The %TOM was found to be the single most important factor for the observed differences in meiofauna assemblage structure at tourist versus non-tourist beaches in both the Mediterranean and the Baltic region. The free-living nematode assemblages from tourist upper zones depart significantly from expectations based on random selections from the regional nematode species pool. Furthermore upper zone assemblages are characterised by a low species diversity consisting of taxonomically closely related nematode species with r-strategist features. Generally, faunal differences between tourist and non-tourist beaches are decreasing towards the lower beach zones.

Zone separator for multiple zone vessels

DOEpatents

Jones, John B.

1983-02-01

A solids-gas contact vessel, having two vertically disposed distinct reaction zones, includes a dynamic seal passing solids from an upper to a lower zone and maintaining a gas seal against the transfer of the separate treating gases from one zone to the other, and including a stream of sealing fluid at the seal.

Hydration-reduced lattice thermal conductivity of olivine in Earth's upper mantle.

PubMed

Chang, Yun-Yuan; Hsieh, Wen-Pin; Tan, Eh; Chen, Jiuhua

2017-04-18

Earth's water cycle enables the incorporation of water (hydration) in mantle minerals that can influence the physical properties of the mantle. Lattice thermal conductivity of mantle minerals is critical for controlling the temperature profile and dynamics of the mantle and subducting slabs. However, the effect of hydration on lattice thermal conductivity remains poorly understood and has often been assumed to be negligible. Here we have precisely measured the lattice thermal conductivity of hydrous San Carlos olivine (Mg 0.9 Fe 0.1 ) 2 SiO 4 (Fo90) up to 15 gigapascals using an ultrafast optical pump-probe technique. The thermal conductivity of hydrous Fo90 with ∼7,000 wt ppm water is significantly suppressed at pressures above ∼5 gigapascals, and is approximately 2 times smaller than the nominally anhydrous Fo90 at mantle transition zone pressures, demonstrating the critical influence of hydration on the lattice thermal conductivity of olivine in this region. Modeling the thermal structure of a subducting slab with our results shows that the hydration-reduced thermal conductivity in hydrated oceanic crust further decreases the temperature at the cold, dry center of the subducting slab. Therefore, the olivine-wadsleyite transformation rate in the slab with hydrated oceanic crust is much slower than that with dry oceanic crust after the slab sinks into the transition zone, extending the metastable olivine to a greater depth. The hydration-reduced thermal conductivity could enable hydrous minerals to survive in deeper mantle and enhance water transportation to the transition zone.

The Importance of Southern Hemisphere CZOs for Evaluating Spatial Patterns of Chemical Structure in the Critical Zone and Assisting Human Development

NASA Astrophysics Data System (ADS)

Chadwick, O.

2014-12-01

The US Critical Zone Exploration Network (CZEN) is a network of sites designed to provide a better understanding of the integrated Earth surface system. The capacity of the critical zone to withstand perturbations, whether driven by climate, land use change, or spread of invasive species, depends on its chemical composition and physical state, which in turn depends on the time evolution of the critical zone. Many temperate and/or tectonically active critical zones contain a relatively short history due to rapid erosion but tectonically quiescent, tropical regions of the planet contain much longer records that need to be understood to cover the full suite of critical zone processes. Southern Hemisphere Critical Zone Observatories such as those proposed for Kruger National Park (KNP) in South Africa and for portions of the Yilgarn Craton in Western Australa will allow us to extend our temporal understanding of development of spatial heterogeneity in the chemical and physical structure of the critical zone. In addition to considering Earth and climate boundary conditions, these sites incorporate the roles that humans play in driving critical zone processes. For instance along the edges of KNP there is strong evidence of soil erosions due to periurbanization and small-scale agriculture. The existence of KNP provides an important contrast between a "natural" and "human-dominated" landscape that can be exploited to evaluate human impacts on critical zone resources and to develop targeted mitigation strategies. Western Australia has an exploitive economy that relies on large-scale agriculture and mineral extraction, both are intensive users of water which is scarce. The proposed CZO there will be partly focused on managing water under intense economic pressures. It is evident that if funding can be found for these sites they will enhance both critical zone science and practical applied science.

The Lindi Formation (upper Albian-Coniacian) and Tanzania Drilling Project Sites 36-40 (Lower Cretaceous to Paleogene): Lithostratigraphy, biostratigraphy and chemostratigraphy

NASA Astrophysics Data System (ADS)

Jiménez Berrocoso, Álvaro; Huber, Brian T.; MacLeod, Kenneth G.; Petrizzo, Maria Rose; Lees, Jacqueline A.; Wendler, Ines; Coxall, Helen; Mweneinda, Amina K.; Falzoni, Francesca; Birch, Heather; Haynes, Shannon J.; Bown, Paul R.; Robinson, Stuart A.; Singano, Joyce M.

2015-01-01

The 2009 Tanzania Drilling Project (TDP) expedition to southeastern Tanzania cored a total of 572.3 m of sediments at six new mid-Cretaceous to mid-Paleocene boreholes (TDP Sites 36, 37, 38, 39, 40A, 40B). Added to the sites drilled in 2007 and 2008, the new boreholes confirm the common excellent preservation of planktonic and benthic foraminifera and calcareous nannofossils from core samples that will be used for biostratigraphy, evolutionary studies, paleoceanography and climatic reconstructions from the Tanzanian margin, with implications elsewhere. The new sites verify the presence of a relatively expanded Upper Cretaceous succession in the region that has allowed a new stratigraphic unit, named here as the Lindi Formation (Fm), to be formally defined. The Lindi Fm (upper Albian to Coniacian), extending ∼120 km between Kilwa and Lindi, comprises a 335-m-thick, outer-shelf to upper-slope unit, consisting of dark gray claystone and siltstone interbeds, common finely-laminated intervals, minor cm-thick sandstones and up to 2.6% organic carbon in the Turonian. A subsurface, composite stratotype section is proposed for the Lindi Fm, with a gradational top boundary with the overlying Nangurukuru Fm (Santonian to Maastrichtian) and a sharp bottom contact with underlying upper Albian sandstones. The section cored at TDP Sites 36 and 38 belongs to the Lindi Fm and are of lower to middle Turonian age (planktonic foraminifera Whiteinella archaeocretacea to Helvetoglobotruncana helvetica Zones and nannofossils subzones UC6b ± UC7). The lower portion of TDP Site 39 (uppermost part of the Lindi Fm) is assigned to the lower to upper Coniacian (planktonic foraminifera Dicarinella concavata Zone and nannofossils zone UC 10), while the remaining part of this site is attributed to the Coniacian-Santonian transition and younger Santonian (planktonic foraminifera D. asymetrica Zone and upper part of nannofossils zone UC10). TDP Site 37 recovered relatively expanded (150 m thick), monotonous calcareous claystones from the lower to upper Maastrichtian (planktonic foraminifera Pseudoguembelina palpebra to Abathomphalus mayaroensis Zones and nannofossils zones UC19 to UC20aTP) that were separated by a hiatus and/or a faulted contact from overlying brecciated carbonates of the Selandian (middle Paleocene: PF Zone P3 and nannofossil zone NP5). The lower portion of TDP Sites 40A and 40B recovered sandstones and conglomerates barren of microfossils. Their overlying parts were assigned to incomplete sections of the nannofossil zones NC6A to NC8 (uppermost Barremian to lower Albian). Benthic foraminiferal assemblages allowed the Barremian to lower Aptian to be identified in TDP Sites 40A and 40B, while the upper Aptian to middle Albian (Hedbergella trocoidea to Ticinella primula Zones) were assigned using planktonic foraminifera. Cores recovered at TDP 39 (Coniacian-Santonian) and at TDP Sites 40A and 40B (Barremian-middle Albian) represent the first time that these two intervals have been continuously cored and publicly documented in Tanzania. Bulk sediment isotope records generated for the new sites show lower δ18Ocarb values in the Turonian and Santonian (∼-3.5‰ to -5‰) than in the Maastrichtian (∼-3‰), a situation consistent with extreme global warmth in the older intervals and cooling toward the end of the Cretaceous. Also, similar to Turonian sites from previous TDP expeditions, a negative δ13Corg excursion was detected across the W. archaeocretacea-H. helvetica boundary of TDP Site 36 (close to, but above, the Cenomanian-Turonian boundary). This excursion probably responded to local processes in the region, but it is unknown whether they were related to the recovery phase from Ocean Anoxic Event 2.

Mass-specific respiration of mesozooplankton and its role in the maintenance of an oxygen-deficient ecological barrier (BEDOX) in the upwelling zone off Chile upon presence of a shallow oxygen minimum zone

NASA Astrophysics Data System (ADS)

Donoso, Katty; Escribano, Ruben

2014-01-01

A shallow oxygen minimum zone (OMZ) in the coastal upwelling zone off Chile may vertically confine most zooplankton to a narrow (< 50 m) upper layer. From laboratory experiments, we estimated oxygen consumption of the mesozooplankton community obtained in Bay of Mejillones, northern Chile (23°S) in May 2010, December 2010 and August 2011. Mass-specific respiration rates were in the range of 8.2-24.5 μmol O2 mg dry mass- 1 day- 1, at an average temperature of 12 °C. Estimates of the mesozooplankton biomass in the water column indicated that its aerobic respiration may remove daily a maximum of about 20% of oxygen available at the base of the oxycline. Since previous work indicates that zooplankton aggregate near the base of the oxycline, the impact of aerobic respiration on oxygen content might be even stronger at this depth. Mesozooplankton respiration, along with community respiration by microorganisms near the base of the oxycline and a strongly stratified condition (limiting vertical flux of O2), are suggested as being critical factors causing and maintaining a persistent subsurface oxygen-deficient ecological barrier (BEDOX) in the upwelling zone. This BEDOX layer can have a major role in affecting and regulating zooplankton distribution and their dynamics in the highly productive coastal upwelling zone of the Humboldt Current System.

Dynamics explorer interdisciplinary scientist investigations

NASA Technical Reports Server (NTRS)

Kozyra, Janet U.; Nagy, A. F.

1994-01-01

This document is a final report on research activities and accomplishments that occurred during the funding period of 10-1-90 through 1-30-94. The focus of our interdisciplinary investigation during the Dynamics Explorer Mission was on the complex coupling processes that tap the magnetic-storm energy, stored in the ring current particle reservoir, and transport this energy into the subauroral, midlatitude and even equatorial ionospheric regions. The transport of energy through the inner magnetosphere and into the underlying ionospheric regions is a critical element in our understanding of the impact of solar and magnetic disturbances on upper atmospheric and ionospheric regions equatorward of the auroral zone.

Upper Tithonian ammonites (Himalayitidae Spath, 1925 and Neocomitidae Salfeld, 1921) from Charens (Drôme, France)

NASA Astrophysics Data System (ADS)

Frau, Camille; Bulot, Luc G.; Wimbledon, William A. P.; Ifrim, Christina

2016-12-01

This contribution focuses on the Perisphinctoidea ammonite taxa from the Upper Tithonian at Charens (Drôme, south-east France). Emphasis is laid on five genera that belong to the families Himalayitidae and Neocomitidae. We document the precise vertical range of the index-species Micracanthoceras microcanthum, and a comparative ontogenetic- biometric analysis sheds new light on its range of variation and dimorphism as compared to the bestknown Spanish populations. As herein understood, the lower boundary of the M. microcanthum Zone (base of the Upper Tithonian) is fixed at the FAD of its index species. The faunal assemblages and species distribution of the P. andreaei Zone are rather similar to those described at the key-section of Le Chouet as confirmed by the co-occurrence of the genera Protacanthodiscus, Boughdiriella and Pratumidiscus. New palaeontological evidence supports the view that the basal Neocomitidae Busnardoiceras busnardoi was derived from Protacanthodiscus andreaei in the upper part of the P. andreaei Zone.

Three-dimensional velocity structure of crust and upper mantle in southwestern China and its tectonic implications

USGS Publications Warehouse

Wang, Chun-Yong; Chan, W.W.; Mooney, W.D.

2003-01-01

Using P and S arrival times from 4625 local and regional earthquakes recorded at 174 seismic stations and associated geophysical investigations, this paper presents a three-dimensional crustal and upper mantle velocity structure of southwestern China (21??-34??N, 97??-105??E). Southwestern China lies in the transition zone between the uplifted Tibetan plateau to the west and the Yangtze continental platform to the east. In the upper crust a positive velocity anomaly exists in the Sichuan Basin, whereas a large-scale negative velocity anomaly exists in the western Sichuan Plateau, consistent with the upper crustal structure under the southern Tibetan plateau. The boundary between these two anomaly zones is the Longmen Shan Fault. The negative velocity anomalies at 50-km depth in the Tengchong volcanic area and the Panxi tectonic zone appear to be associated with temperature and composition variations in the upper mantle. The Red River Fault is the boundary between the positive and negative velocity anomalies at 50-km depth. The overall features of the crustal and the upper mantle structures in southwestern China are a low average velocity, large crustal thickness variations, the existence of a high-conductivity layer in the crust or/and upper mantle, and a high heat flow value. All these features are closely related to the collision between the Indian and the Asian plates.

Impact of great subduction earthquakes on the long-term forearc morphology, insight from mechanical modelling

NASA Astrophysics Data System (ADS)

Cubas, Nadaya

2017-04-01

The surge of great subduction earthquakes during the last fifteen years provided numerous observations requiring revisiting our understanding of large seismic events mechanics. For instance, we now have clear evidence that a significant part of the upper plate deformation is permanently acquired. The link between great earthquakes and long-term deformation offers a new perspective for the relief construction understanding. In addition, a better understanding of these relations could provide us with new constraints on earthquake mechanics. It is also of fundamental importance for seismic risk assessment. In this presentation, I will compile recent results obtained from mechanical modelling linking megathrust ruptures with upper-plate permanent deformation and discuss their impact. We will first show that, in good accordance with lab experiments, aseismic zones are characterized by frictions larger or equal to 0.1 whereas seismic asperities have dynamic frictions lower than 0.05. This difference will control the long-term upper-plate morphology. The larger values along aseismic zones allow the wedge to reach the critical state, and will lead to active thrust systems forming a relief. On the contrary, low dynamic friction along seismic asperities will place the taper in the sub-critical domain impeding any internal deformation. This will lead to the formation of forearc basins inducing negative gravity anomalies. Since aseismic zones have higher friction and larger taper, fully creeping segments will tend to develop peninsulas. On the contrary, fully locked segments with low dynamic friction and very low taper will favor subsiding coasts. The taper variation due to megathrust friction is also expressed through a correlation between coast-to-trench distance and forearc coupling (e.g., Mexican and South-American subduction zones). We will then discuss how variations of frictional properties along the megathrust can induce splay fault activation. For instance, we can reactivate normal faults at the down-dip limit of the seismogenic zone or at an increasing slip transition (e.g., Chile and Japan). Finally, we will show that the fault vergence is controlled by the frictional properties. Sudden and successive decreases of the megathrust effective friction during frontal propagation of earthquakes will lead to the formation of landward-vergent frontal thrusts in the accretionary prism. Therefore, a particular attention needs to be paid to accretionary prisms with normal faults implying large up-dip ruptures (e.g., Alaska and Japan) or with frontal landward-vergent thrust faults, markers of past seafloor coseismic ruptures leading to very large tsunamis (e.g., Cascadia and Sumatra). If the forearc long-term deformation seems in good accordance with our understanding of earthquake mechanics, recent studies have pointed to a major discrepancy between short- and long-term deformation at the coast (i.e., the Central Andes subduction zone). An analogue discrepancy has been pointed out for the Himalaya after the 2015 Mw 7.8 Gorkha earthquake. Melnick (2016) proposed that the coastal long-term deformation could be related to deep and less frequent earthquakes instead of standard subduction events. It is now of fundamental importance to understand the link between the coastal long-term record and the short-term deformation for seismic risk assessment and relief building processes understanding. It will probably constitute the next challenge for mechanical modelling.

The ambient acoustic environment in Laguna San Ignacio, Baja California Sur, Mexico.

PubMed

Seger, Kerri D; Thode, Aaron M; Swartz, Steven L; Urbán, Jorge R

2015-11-01

Each winter gray whales (Eschrichtius robustus) breed and calve in Laguna San Ignacio, Mexico, where a robust, yet regulated, whale-watching industry exists. Baseline acoustic environments in LSI's three zones were monitored between 2008 and 2013, in anticipation of a new road being paved that will potentially increase tourist activity to this relatively isolated location. These zones differ in levels of both gray whale usage and tourist activity. Ambient sound level distributions were computed in terms of percentiles of power spectral densities. While these distributions are consistent across years within each zone, inter-zone differences are substantial. The acoustic environment in the upper zone is dominated by snapping shrimp that display a crepuscular cycle. Snapping shrimp also affect the middle zone, but tourist boat transits contribute to noise distributions during daylight hours. The lower zone has three source contributors to its acoustic environment: snapping shrimp, boats, and croaker fish. As suggested from earlier studies, a 300 Hz noise minimum exists in both the middle and lower zones of the lagoon, but not in the upper zone.

Altitude effects on technology and productivity of small bovine farms (milk meat) in Veracruz (Gulf of Mexico).

PubMed

Ruíz-Guevara, C; De León-González, F; Soriano-Robles, R; Pérez-Carrera, A L; García-Hernández, L A

2018-03-01

The dual-purpose bovine system represents 98.4% of the bovine livestock of Veracruz, the main cattle-producing state of Mexico. This system supplies calves to meat companies, a sector in which Veracruz has been the national leader in the last decade. The objective of the present study was to analyze the effect of the altitudinal zonation of farms on livestock technology and productivity in a microbasin of the Gulf of Mexico where small farms predominate. Structured interviews were applied to producers located in three altitudinal zones (at average altitudes of 50, 140, and 450 m, respectively, for lower, middle, and upper zones). Sample size was 135 farms having similar land surface (within a range of 15-22 ha). The results indicated multiple differences among farms located in the three zones. Farms in the middle and lower zones presented higher productive indicators than those in the upper zone. Differences in herd structure and management resulted in important differences in productivity, income, and profits in milk and calf production. We concluded from this study that altitudinal zonation in Veracruz had a clear effect on the differentiation of small farms, which are representative of dual-purpose cattle. The upper zone performs cattle activity under conditions with greater disadvantages in the analyzed region.

Microbial abundance in the deep subsurface of the Chesapeake Bay impact crater: Relationship to lithology and impact processes

USGS Publications Warehouse

Cockell, Charles S.; Gronstal, Aaron L.; Voytek, Mary A.; Kirshtein, Julie D.; Finster, Kai; Sanford, Ward E.; Glamoclija, Mihaela; Gohn, Gregroy S.; Powars, David S.; Horton, J. Wright

2009-01-01

Asteroid and comet impact events are known to cause profound disruption to surface ecosystems. The aseptic collection of samples throughout a 1.76-km-deep set of cores recovered from the deep subsurface of the Chesapeake Bay impact structure has allowed the study of the subsurface biosphere in a region disrupted by an impactor. Microbiological enumerations suggest the presence of three major microbiological zones. The upper zone (127–867 m) is characterized by a logarithmic decline in microbial abundance from the surface through the postimpact section of Miocene to Upper Eocene marine sediments and across the transition into the upper layers of the impact tsunami resurge sediments and sediment megablocks. In the middle zone (867–1397 m) microbial abundances are below detection. This zone is predominantly quartz sand, primarily composed of boulders and blocks, and it may have been mostly sterilized by the thermal pulse delivered during impact. No samples were collected from the large granite block (1096–1371 m). The lowest zone (below 1397 m) of increasing microbial abundance coincides with a region of heavily impact-fractured, hydraulically conductive suevite and fractured schist. These zones correspond to lithologies influenced by impact processes. Our results yield insights into the influence of impacts on the deep subsurface biosphere.

Sequence-Stratigraphic Analysis of the Regional Observation Monitoring Program (ROMP) 29A Test Corehole and Its Relation to Carbonate Porosity and Regional Transmissivity in the Floridan Aquifer System, Highlands County, Florida

USGS Publications Warehouse

Ward, W. C.; Cunningham, K.J.; Renken, R.A.; Wacker, M.A.; Carlson, J.I.

2003-01-01

An analysis was made to describe and interpret the lithology of a part of the Upper Floridan aquifer penetrated by the Regional Observation Monitoring Program (ROMP) 29A test corehole in Highlands County, Florida. This information was integrated into a one-dimensional hydrostratigraphic model that delineates candidate flow zones and confining units in the context of sequence stratigraphy. Results from this test corehole will serve as a starting point to build a robust three-dimensional sequence-stratigraphic framework of the Floridan aquifer system. The ROMP 29A test corehole penetrated the Avon Park Formation, Ocala Limestone, Suwannee Limestone, and Hawthorn Group of middle Eocene to Pliocene age. The part of the Avon Park Formation penetrated in the ROMP 29A test corehole contains two composite depositional sequences. A transgressive systems tract and a highstand systems tract were interpreted for the upper composite sequence; however, only a highstand systems tract was interpreted for the lower composite sequence of the deeper Avon Park stratigraphic section. The composite depositional sequences are composed of at least five high-frequency depositional sequences. These sequences contain high-frequency cycle sets that are an amalgamation of vertically stacked high-frequency cycles. Three types of high-frequency cycles have been identified in the Avon Park Formation: peritidal, shallow subtidal, and deeper subtidal high-frequency cycles. The vertical distribution of carbonate-rock diffuse flow zones within the Avon Park Formation is heterogeneous. Porous vuggy intervals are less than 10 feet, and most are much thinner. The volumetric arrangement of the diffuse flow zones shows that most occur in the highstand systems tract of the lower composite sequence of the Avon Park Formation as compared to the upper composite sequence, which contains both a backstepping transgressive systems tract and a prograding highstand systems tract. Although the porous and permeable layers are not thick, some intervals may exhibit lateral continuity because of their deposition on a broad low-relief ramp. A thick interval of thin vuggy zones and open faults forms thin conduit flow zones mixed with relatively thicker carbonate-rock diffuse flow zones between a depth of 1,070 and 1,244 feet below land surface (bottom of the test corehole). This interval is the most transmissive part of the Avon Park Formation penetrated in the ROMP 29A test corehole and is included in the highstand systems tract of the lower composite sequence. The Ocala Limestone is considered to be a semiconfining unit and contains three depositional sequences penetrated by the ROMP 29A test corehole. Deposited within deeper subtidal depositional cycles, no zones of enhanced porosity and permeability are expected in the Ocala Limestone. A thin erosional remnant of the shallow marine Suwannee Limestone overlies the Ocala Limestone, and permeability seems to be comparatively low because moldic porosity is poorly connected. Rocks that comprise the lower Hawthorn Group, Suwannee Limestone, and Ocala Limestone form a permeable upper zone of the Upper Floridan aquifer, and rocks of the lower Ocala Limestone and Avon Park Formation form a permeable lower zone of the Upper Floridan aquifer. On the basis of a preliminary analysis of transmissivity estimates for wells located north of Lake Okeechobee, spatial relations among groups of relatively high and low transmissivity values within the upper zone are evident. Upper zone transmissivity is generally less than 10,000 feet squared per day in areas located south of a line that extends through Charlotte, Sarasota, DeSoto, Highlands, Polk, Osceola, Okeechobee, and St. Lucie Counties. Transmissivity patterns within the lower zone of the Avon Park Formation cannot be regionally assessed because insufficient data over a wide areal extent have not been compiled.

A Bayesian method to quantify azimuthal anisotropy model uncertainties: application to global azimuthal anisotropy in the upper mantle and transition zone

NASA Astrophysics Data System (ADS)

Yuan, K.; Beghein, C.

2018-04-01

Seismic anisotropy is a powerful tool to constrain mantle deformation, but its existence in the deep upper mantle and topmost lower mantle is still uncertain. Recent results from higher mode Rayleigh waves have, however, revealed the presence of 1 per cent azimuthal anisotropy between 300 and 800 km depth, and changes in azimuthal anisotropy across the mantle transition zone boundaries. This has important consequences for our understanding of mantle convection patterns and deformation of deep mantle material. Here, we propose a Bayesian method to model depth variations in azimuthal anisotropy and to obtain quantitative uncertainties on the fast seismic direction and anisotropy amplitude from phase velocity dispersion maps. We applied this new method to existing global fundamental and higher mode Rayleigh wave phase velocity maps to assess the likelihood of azimuthal anisotropy in the deep upper mantle and to determine whether previously detected changes in anisotropy at the transition zone boundaries are robustly constrained by those data. Our results confirm that deep upper-mantle azimuthal anisotropy is favoured and well constrained by the higher mode data employed. The fast seismic directions are in agreement with our previously published model. The data favour a model characterized, on average, by changes in azimuthal anisotropy at the top and bottom of the transition zone. However, this change in fast axes is not a global feature as there are regions of the model where the azimuthal anisotropy direction is unlikely to change across depths in the deep upper mantle. We were, however, unable to detect any clear pattern or connection with surface tectonics. Future studies will be needed to further improve the lateral resolution of this type of model at transition zone depths.

Higher species richness of octocorals in the upper mesophotic zone in Eilat (Gulf of Aqaba) compared to shallower reef zones

NASA Astrophysics Data System (ADS)

Shoham, Erez; Benayahu, Yehuda

2017-03-01

Mesophotic coral-reef ecosystems (MCEs), which comprise the light-dependent communities of corals and other organisms found at depths between 30 and 150 m, have received very little study to date. However, current technological advances, such as remotely operated vehicles and closed-circuit rebreather diving, now enable their thorough investigation. Following the reef-building stony corals, octocorals are the second most common benthic component on many shallow reefs and a major component on deep reefs, the Red Sea included. This study is the first to examine octocoral community features on upper MCEs based on species-level identification and to compare them with the shallower reef zones. The study was carried out at Eilat (Gulf of Aqaba, northern Red Sea), comparing octocoral communities at two mesophotic reefs (30-45 m) and two shallow reef zones (reef flat and upper fore-reef) by belt transects. A total of 30 octocoral species were identified, with higher species richness on the upper MCEs compared to the shallower reefs. Although the MCEs were found to host a higher number of species than the shallower reefs, both featured a similar diversity. Each reef zone revealed a unique octocoral species composition and distinct community structure, with only 16% of the species shared by both the MCEs and the shallower reefs. This study has revealed an almost exclusive dominance of zooxanthellate species at the studied upper MCE reefs, thus indicating an adequate light regime for photosynthesis there. The findings should encourage similar studies on other reefs, aimed at understanding the spatiotemporal features and ecological role of octocorals in reef ecosystems down to the deepest limit of the MCEs.

Geology of Paleozoic Rocks in the Upper Colorado River Basin in Arizona, Colorado, New Mexico, Utah, and Wyoming, Excluding the San Juan Basin

USGS Publications Warehouse

Geldon, Arthur L.

2003-01-01

The geology of the Paleozoic rocks in the Upper Colorado River Basin in Arizona, Colorado, New Mexico, Utah, and Wyoming, was studied as part of the U.S. Geological Survey's Regional Aquifer-System Analysis Program to provide support for hydrogeological interpretations. The study area is segmented by numerous uplifts and basins caused by folding and faulting that have recurred repeatedly from Precambrian to Cenozoic time. Paleozoic rocks in the study area are 0-18,000 feet thick. They are underlain by Precambrian igneous, metamorphic, and sedimentary rocks and are overlain in most of the area by Triassic formations composed mostly of shale. The overlying Mesozoic and Tertiary rocks are 0-27,000 feet thick. All Paleozoic systems except the Silurian are represented in the region. The Paleozoic rocks are divisible into 11 hydrogeologic units. The basal hydrogeologic unit consisting of Paleozoic rocks, the Flathead aquifer, predominantly is composed of Lower to Upper Cambrian sandstone and quartzite. The aquifer is 0-800 feet thick and is overlain gradationally to unconformably by formations of Cambrian to Mississippian age. The Gros Ventre confining unit consists of Middle to Upper Cambrian shale with subordinate carbonate rocks and sandstone. The confining unit is 0-1,100 feet thick and is overlain gradationally to unconformably by formations of Cambrian to Mississippian age. The Bighom aquifer consists of Middle Cambrian to Upper Ordovician limestone and dolomite with subordinate shale and sandstone. The aquifer is 0-3,000 feet thick and is overlain unconformably by Devonian and Mississipplan rocks. The Elbert-Parting confining unit consists of Lower Devonian to Lower Mississippian limestone, dolomite, sandstone, quartzite, shale, and anhydrite. It is 0-700 feet thick and is overlain conformably to unconformably by Upper Devonian and Mississippian rocks. The Madison aquifer consists of two zones of distinctly different lithology. The lower (Redwall-Leadville) zone is 0-2,500 feet thick and is composed almost entirely of Upper Devonian to Upper Mississippian limestone, dolomite, and chert. The overlying (Darwin-Humbug) zone is 0-800 feet thick and consists of Upper Mississippian limestone, dolomite, sandstone, shale, gypsum, and solution breccia. The Madison aquifer is overlain conformably by Upper Mississippian and Pennsylvanian rocks. The Madison aquifer in most areas is overlain by Upper Mississippian to Middle Pennsylvanian rocks of the Four Comers confining unit. The lower part of this confining unit, the Belden-Molas subunit, consists of as much as 4,300 feet of shale with subordinate carbonate rocks, sandstone, and minor gypsum. The upper part of the confining unit, the Paradox-Eagle Valley subunit, in most places consists of as much as 9,700 feet of interbedded limestone, dolomite, shale, sandstone, gypsum, anhydrite, and halite. Locally, the evaporitic rocks are deformed into diapirs as much as 15,000 feet thick. The Four Corners confining unit is overlain gradationally to disconformably by Pennsylvanian rocks. The uppermost Paleozoic rocks comprise the Canyonlands aquifer, which is composed of three zones with distinctly different lithologies. The basal (Cutler-Maroon) zone consists of as much as 16,500 feet of Lower Pennsylvanian to Lower Permian sandstone, conglomerate, shale, limestone, dolomite, and gypsum. The middle (Weber-De Chelly) zone consists of as much as 4,000 feet of Middle Pennsylvanian to Lower Permian quartz sandstone with minor carbonate rocks and shale. The upper (Park City-State Bridge) zone consists of as much as 800 feet of Lower to Upper Permian limestone, dolomite, shale, sandstone, phosphorite, chert, and gypsum. The Canyonlands aquifer is overlain disconformably to unconformably by formations of Triassic and Jurassic age.

New insight into the Upper Mantle Structure Beneath the Pacific Ocean Using PP and SS Precursors

NASA Astrophysics Data System (ADS)

Gurrola, H.; Rogers, K. D.

2013-12-01

The passing of the EarthScope Transportable array has provided a dense data set that enabled beam forming of SS and PP data that resultes in improved frequency content to as much a 1 Hz in the imaging of upper mantle structure. This combined with the application of simultaneous iterative deconvolution has resulted in images to as much as 4 Hz. The processing however results in structure being averaged over regions of 60 to 100 km in radius. This is becomes a powerful new tool to image the upper mantle beneath Oceanic regions where locating stations is expensive and difficult. This presentation will summarize work from a number of regions as to new observations of the upper mantle beneath the Pacific and Arctic Oceans. Images from a region of the Pacific Ocean furthest from hot spots or subduction zones (we will refer to this as the 'reference region'). show considerable layering in the upper mantle. The 410 km discontinuity is always imaged using these tools and appears to be a very sharp boundary. It does usually appear as an isolated positive phase. There appears to be a LAB at ~100 km as expected but there is a strong negative phase at ~ 200 km with a positive phase 15 km deeper. This is best explained as a lens of partial melt as expected for this depth based on the geothermal gradient. If so this should be a low friction point and so we would expect it to accommodate plate motion. Imaging of the Aleutian subduction zone does show the 100 km deep LAB as it descends but this 200 km deep horizon appears as a week descending positive anomaly without the shallower negative pulse. In addition to the 410, 100 and 200 km discontinuities there are a number of paired anomalies, between the 200 and 400 km depths, with a negative pulse 15 to 20 km shallower then the positive pulse. We do not believe these are side lobes or we would see side lobes on the 100 km and 410 km discontinuities. We believe these to be the result of friction induced partial melt along zones of critical failure to accommodate differential mantle flow with depth. The paired layers disappear beneath the Hawaiian Island chain. We believe heat from the hot spot warms the mantle beneath the Hawaiian island chain so flow is more easily accommodated. As a result the lenses of melt disappear in the region near hot spots.

Auxin efflux facilitator and auxin dynamism responsible for the gravity-regulated development of peg in cucumber seedlings

NASA Astrophysics Data System (ADS)

Takahashi, Hideyuki; Watanabe, Chiaki; Fujii, Nobuharu; Miyazawa, Yutaka

Cucumber seedlings develop a protuberance, peg, by which seed coats are pulled out just af-ter germination. The peg is usually formed on the lower side of the transition zone between hypocotyl and root of the seedlings grown in a horizontal position. Our previous spaceflight experiment showed that unilateral positioning of a peg in cucumber seedlings occurred due to its suppression on the upper side of the transition zone because seedlings grown in microgravity developed a peg on each side of the transition zone. We also showed that auxin was a major factor responsible for peg development. There was a redistribution of auxin in the gravistimu-lated transition zone, decreasing IAA level on the upper side, and IAA application induced a peg on both lower and upper sides of the transition zone. In addition, peg was released from its suppression in the seedlings treated with inhibitors of auxin efflux. Namely, two pegs devel-oped in the TIBA-treated seedlings even when they were grown in a horizontal position. These results imply that a reduction of auxin level due to its efflux is required for the suppression of peg development on the upper side of the transition zone in a horizontal position. To under-stand molecular mechanism underlying the negative control of morphogenesis by graviresponse in cucumber seedlings, we isolated cDNAs of auxin efflux facilitators, CsPINs, from cucumber and examined the expressions of their proteins, in relation to the redistribution of endogenous auxin and peg development. We isolated six cDNAs of PIN homologues CsPIN1 to CsPIN6 from cucumber. By immunohistochemical study using some of their anti-bodies, we revealed that CsPIN1 was localized in endodermis, vascular tissue and pith around the transition zone of cucumber seedlings. In cucumber seedlings grown in a vertical position with radicles pointing down, CsPIN1 in endodermal cells was mainly localized on the plasma membrane neighboring vascular bundle but not on the plasma membrane next to the cortex. This CsPIN1 localization could play a role in transporting auxin from cortex to vascular bundle. In both vascular and pith tissues, CsPIN1 was localized on the bottom plasma membrane of the cells, which could allow auxin to move toward the roots. In the seedlings grown in a horizontal position, endoder-mal cells situated above the vascular bundle localized CsPIN1 on the lower plasma membrane, whereas the polarized localization of CsPIN1 in endodermal cells situated below the vascular bundle became less clear. This differential expression of CsPIN1 in the endodermis commenced within 30 min after gravistimulation. We measured endogenous IAA contents in the transi-tion zone of the 24-hour-old seedlings. In the longitudinally halved transition zone of seedlings grown in a horizontal position, free IAA content was significantly lowered in the upper side, compared to that of the lower side or either side of the transition zone in a vertical position. When 24-hour-old seedlings grown in a vertical position were gravistimulated by reorienting them to the horizontal, free IAA in the lower side of the transition zone increased by 30 min after gravistimulation and eventually decreased to the control level by 180 min after gravistim-ulation. IAA content in the upper side of the transition zone did not change much and was comparable to that in the vertical transition zone during 180 min after gravistimulation. Thus, it appears that gravistimulation causes an immediate increase of IAA level in the lower side and its eventual decrease in the upper side of the transition zone. The gravity-induced changes in CsPIN1 localization in endodermal cells could be involved in auxin redistribution that leads to unilateral positioning of a peg in cucumber seedlings.

Microstructural evidence for northeastward movement on the Chocolate Mountains fault zone, southeastern California

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

Simpson, C.

1990-01-10

Microstructural analysis of rocks from the Chocolate Mountains fault zone, Gavilan Hills area, southeastern California, show unequivocal evidence for northeast directed transport of the upper plate gneisses over lower plate Orocopia schists. Samples were taken from transects through the fault zone. Prefaulting fabrics in upper plate gneisses show a strong component of northeast directed rotational deformation under lower amphibolite facies conditions. In contrast, prefaulting lower plate Orocopia schists show strongly coaxial fabrics (minimum stretch value of 2.2) formed at greenschist grade. Mylonitic fabrics associated with the Chocolate Mountains fault are predominantly northeast directed shear bands that are unidirectional (northeastward) inmore » the gneisses but bi-directional in the schists, suggesting a significant component of nonrotational deformation occurred in the Orocopia schists during and after emplacement of the upper plate. The kinematic findings are in agreement with Dillon et al. (1989), who found that the vergence of asymmetrical folds within the fault zone indicates overthrusting to the northeast, toward the craton, in this region. The available evidence favors a single protracted northeastward movement on the Chocolate Mountains fault zone with temperatures waning as deformation proceeded.« less

New biostratigraphic data on an Upper Hauterivian–Upper Barremian ammonite assemblage from the Dolomites (Southern Alps, Italy)

PubMed Central

Lukeneder, Alexander

2012-01-01

A biostratigraphic subdivision, based on ammonites, is proposed for the Lower Cretaceous pelagic to hemipelagic succession of the Puez area (Southern Alps, Italy). Abundant ammonites enable recognition of recently established Mediterranean ammonite zones from the upper Hauterivian Balearites balearis Zone (Crioceratites krenkeli Subzone) to the upper Barremian Gerhardtia sartousiana Zone (Gerhardtia sartousiana Subzone). Ammonites are restricted to the lowermost part of the Puez Formation, the Puez Limestone Member (ca. 50 m; marly limestones; Hauterivian–Barremian). Numerous ammonite specimens are documented for the first time from the Southern Alps (e.g., Dolomites). Ammonite abundances are clearly linked to sea-level changes from Late Hauterivian to mid Late Barremian times. Abundance and diversity peaks occur during phases of high sea-level pulses and the corresponding maximum flooding surfaces (P. mortilleti/P. picteti and G. sartousiana zones). The ammonite composition of the Puez Formation sheds light on the Early Cretaceous palaeobiogeography of the Dolomites. It also highlights the palaeoenvironmental evolution of basins and plateaus and provides insights into the faunal composition and distribution within the investigated interval. The intermittent palaeogeographic situation of the Puez locality during the Early Cretaceous serves as a key for understanding Mediterranean ammonite distribution. PMID:27087716

The upper-mantle transition zone beneath the Chile-Argentina flat subduction zone

NASA Astrophysics Data System (ADS)

Bagdo, Paula; Bonatto, Luciana; Badi, Gabriela; Piromallo, Claudia

2016-04-01

The main objective of the present work is the study of the upper mantle structure of the western margin of South America (between 26°S and 36°S) within an area known as the Chile-Argentina flat subduction zone. For this purpose, we use teleseismic records from temporary broad band seismic stations that resulted from different seismic experiments carried out in South America. This area is characterized by on-going orogenic processes and complex subduction history that have profoundly affected the underlying mantle structure. The detection and characterization of the upper mantle seismic discontinuities are useful to understand subduction processes and the dynamics of mantle convection; this is due to the fact that they mark changes in mantle composition or phase changes in mantle minerals that respond differently to the disturbances caused by mantle convection. The discontinuities at a depth of 410 km and 660 km, generally associated to phase changes in olivine, vary in width and depth as a result of compositional and temperature anomalies. As a consequence, these discontinuities are an essential tool to study the thermal and compositional structure of the mantle. Here, we analyze the upper-mantle transition zone discontinuities at a depth of 410 km and 660 km as seen from Pds seismic phases beneath the Argentina-Chile flat subduction.

Glutenite bodies sequence division of the upper Es4 in northern Minfeng zone of Dongying Sag, Bohai Bay Basin, China

NASA Astrophysics Data System (ADS)

Shao, Xupeng

2017-04-01

Glutenite bodies are widely developed in northern Minfeng zone of Dongying Sag. Their litho-electric relationship is not clear. In addition, as the conventional sequence stratigraphic research method drawbacks of involving too many subjective human factors, it has limited deepening of the regional sequence stratigraphic research. The wavelet transform technique based on logging data and the time-frequency analysis technique based on seismic data have advantages of dividing sequence stratigraphy quantitatively comparing with the conventional methods. Under the basis of the conventional sequence research method, this paper used the above techniques to divide the fourth-order sequence of the upper Es4 in northern Minfeng zone of Dongying Sag. The research shows that the wavelet transform technique based on logging data and the time-frequency analysis technique based on seismic data are essentially consistent, both of which divide sequence stratigraphy quantitatively in the frequency domain; wavelet transform technique has high resolutions. It is suitable for areas with wells. The seismic time-frequency analysis technique has wide applicability, but a low resolution. Both of the techniques should be combined; the upper Es4 in northern Minfeng zone of Dongying Sag is a complete set of third-order sequence, which can be further subdivided into 5 fourth-order sequences that has the depositional characteristics of fine-upward sequence in granularity. Key words: Dongying sag, northern Minfeng zone, wavelet transform technique, time-frequency analysis technique ,the upper Es4, sequence stratigraphy

Middle Triassic molluscan fossils of biostratigraphic significance from the Humboldt Range, northwestern Nevada

USGS Publications Warehouse

Silberling, Norman J.; Nichols, K.M.

1982-01-01

Cephalopods and bivalves of the genus Daonella occur at certain levels throughout the Middle Triassic section in the Humboldt Range, northwestern Nevada. These fossiliferous strata are assigned to the Fossil Hill Member and upper member of the Prida Formation, which here forms the oldest part of the Star Peak Group. The distribution and abundance of fossils within the section is uneven, partly because of original depositional patterns within the dominantly calcareous succession and partly because of diagenetic secondary dolomitization and hydrothermal metamorphism in parts of the range.Lower and middle Anisian fossil localities are restricted to the northern part of the range and are scattered, so that only three demonstrably distinct stratigraphic levels are represented. Cephalopods from these localities are characteristic of the Caurus Zone and typify the lower and upper parts of the Hyatti Zone, a new zonal unit whose faunas have affinity with those from the older parts of the Varium Zone in Canada.The upper Anisian and lowermost Ladinian, as exposed in the vicinity of Fossil Hill in the southern part of the range, are extremely fossiliferous. Cephalopod and Daonella shells form a major component of many of the limestone interbeds in the calcareous fine-grained clastic section here. Stratigraphically controlled bedrock collections representing at least 20 successive levels have been made from the Fossil Hill area, which is the type locality for the Rotelliformis, Meeki, and Occidentalis Zones of the upper Anisian and the Subasperum Zone of the lower Ladinian. Above the Subasperum Zone fossils are again scarce; upper Ladinian faunas representing the Daonella lommeli beds occur at only a few places in the upper member of the Prida Formation.Although unevenly fossiliferous, the succession of Middle Triassic cephalopod and Daonella faunas in the Humboldt Range is one of the most complete of any known in the world. Newly collected faunas from this succession provide the basis for revising the classic monograph on Middle Triassic marine invertebrates of North America published in 1914 by J. P. Smith and based largely on stratigraphically uncontrolled collections from the Humboldt Range. Taxonomic treatment of these collections, old and new, from the Humboldt Range provides the documentation necessary to establish this Middle Triassic succession as a biostratigraphic standard of reference.Of the 68 species of ammonites described or discussed, 4 are from the lower Anisian, 20 from the middle Anisian, 39 from the upper Anisian, 4 from the lower Ladinian, and 1 from the upper Ladinian. A few additional ammonite species from other localities in Nevada are also treated in order to clarify their morphologic characteristics and stratigraphic occurrence. Other elements in the Middle Triassic molluscan faunas of the Humboldt Range comprise five species of nautiloids and three of coleoids from the middle and upper Anisian parts of the section. Eight more or less stratigraphically restricted species of Daonella occur in the upper Anisian and Ladinian.

Acoustic explorations of the upper ocean boundary layer

NASA Astrophysics Data System (ADS)

Vagle, Svein

2005-04-01

The upper ocean boundary layer is an important but difficult to probe part of the ocean. A better understanding of small scale processes at the air-sea interface, including the vertical transfer of gases, heat, mass and momentum, are crucial to improving our understanding of the coupling between atmosphere and ocean. Also, this part of the ocean contains a significant part of the total biomass at all trophic levels and is therefore of great interest to researchers in a range of different fields. Innovative measurement plays a critical role in developing our understanding of the processes involved in the boundary layer, and the availability of low-cost, compact, digital signal processors and sonar technology in self-contained and cabled configurations has led to a number of exciting developments. This talk summarizes some recent explorations of this dynamic boundary layer using both active and passive acoustics. The resonant behavior of upper ocean bubbles combined with single and multi-frequency broad band active and passive devices are now giving us invaluable information on air-sea gas transfer, estimation of biological production, marine mammal behavior, wind speed and precipitation, surface and internal waves, turbulence, and acoustic communication in the surf zone.

Progress Report on the US Critical Zone Observatory Program

NASA Astrophysics Data System (ADS)

Barrera, E. C.

2014-12-01

The Critical Zone Observatory (CZO) program supported by the National Science Foundation originated from the recommendation of the Earth Science community published in the National Research Council report "Basic Research Opportunities in Earth Sciences" (2001) to establish natural laboratories to study processes and systems of the Critical Zone - the surface and near-surface environment sustaining nearly all terrestrial life. After a number of critical zone community workshops to develop a science plan, the CZO program was initiated in 2007 with three sites and has now grown to 10 sites and a National Office, which coordinates research, education and outreach activities of the network. Several of the CZO sites are collocated with sites supported by the US Long Term Ecological Research (LTER) and the Long Term Agricultural Research (LTAR) programs, and the National Ecological Observatory Network (NEON). Future collaboration with additional sites of these networks will add to the potential to answer questions in a more comprehensive manner and in a larger regional scale about the critical zone form and function. At the international level, CZOs have been established in many countries and strong collaborations with the US program have been in place for many years. The next step is the development of a coordinated international program of critical zone research. The success of the CZO network of sites can be measured in transformative results that elucidate properties and processes controlling the critical zone and how the critical zone structure, stores and fluxes respond to climate and land use change. This understanding of the critical zone can be used to enhance resilience and sustainability, and restore ecosystem function. Thus, CZO science can address major societal challenges. The US CZO network is a facility open to research of the critical zone community at large. Scientific data and information about the US program are available at www.criticalzone.org.

Conventional and technical diving surveys reveal elevated biomass and differing fish community composition from shallow and upper mesophotic zones of a remote United States coral reef.

PubMed

Muñoz, Roldan C; Buckel, Christine A; Whitfield, Paula E; Viehman, Shay; Clark, Randy; Taylor, J Christopher; Degan, Brian P; Hickerson, Emma L

2017-01-01

The world's coral reefs appear to be in a global decline, yet most previous research on coral reefs has taken place at depths shallower than 30 m. Mesophotic coral ecosystem (depths deeper than ~30 m) studies have revealed extensive, productive habitats and rich communities. Despite recent advances, mesophotic coral ecosystems remain understudied due to challenges with sampling at deeper depths. The few previous studies of mesophotic coral ecosystems have shown variation across locations in depth-specific species composition and assemblage shifts, potentially a response to differences in habitat or light availability/water clarity. This study utilized scuba to examine fish and benthic communities from shallow and upper mesophotic (to 45 m) zones of Flower Garden Banks National Marine Sanctuary (FGBNMS, 28°0'N; 93°50'W) from 2010-2012. Dominant planktivores were ubiquitous in shallow and upper mesophotic habitats, and comparisons with previous shallow research suggest this community distribution has persisted for over 30 years. Planktivores were abundant in shallow low-relief habitats on the periphery of the coral reef, and some of these sites that contained habitat transitioning from high to low relief supported high biomass of benthic predators. These peripheral sites at FGBNMS may be important for the trophic transfer of oceanic energy to the benthic coral reef. Distinct differences between upper mesophotic and shallow communities were also observed. These included greater overall fish (as well as apex predator) biomass in the upper mesophotic, differences in apex predator community composition between depth zones, and greater percent cover of algae, rubble, sand, and sponges in the upper mesophotic. Greater fish biomass in the upper mesophotic and similar fish community composition between depth zones provide preliminary support that upper mesophotic habitats at FGBNMS have the capacity to serve as refugia for the shallow-water reefs. Diving surveys of the upper mesophotic and shallow-water coral reef have revealed valuable information concerning the reef fish community in the northern Gulf of Mexico, with implications for the conservation of apex predators, oceanic coral reefs, and the future management of FGBNMS.

Conventional and technical diving surveys reveal elevated biomass and differing fish community composition from shallow and upper mesophotic zones of a remote United States coral reef

PubMed Central

Buckel, Christine A.; Whitfield, Paula E.; Viehman, Shay; Clark, Randy; Taylor, J. Christopher; Degan, Brian P.; Hickerson, Emma L.

2017-01-01

The world’s coral reefs appear to be in a global decline, yet most previous research on coral reefs has taken place at depths shallower than 30 m. Mesophotic coral ecosystem (depths deeper than ~30 m) studies have revealed extensive, productive habitats and rich communities. Despite recent advances, mesophotic coral ecosystems remain understudied due to challenges with sampling at deeper depths. The few previous studies of mesophotic coral ecosystems have shown variation across locations in depth-specific species composition and assemblage shifts, potentially a response to differences in habitat or light availability/water clarity. This study utilized scuba to examine fish and benthic communities from shallow and upper mesophotic (to 45 m) zones of Flower Garden Banks National Marine Sanctuary (FGBNMS, 28°0ʹN; 93°50ʹW) from 2010–2012. Dominant planktivores were ubiquitous in shallow and upper mesophotic habitats, and comparisons with previous shallow research suggest this community distribution has persisted for over 30 years. Planktivores were abundant in shallow low-relief habitats on the periphery of the coral reef, and some of these sites that contained habitat transitioning from high to low relief supported high biomass of benthic predators. These peripheral sites at FGBNMS may be important for the trophic transfer of oceanic energy to the benthic coral reef. Distinct differences between upper mesophotic and shallow communities were also observed. These included greater overall fish (as well as apex predator) biomass in the upper mesophotic, differences in apex predator community composition between depth zones, and greater percent cover of algae, rubble, sand, and sponges in the upper mesophotic. Greater fish biomass in the upper mesophotic and similar fish community composition between depth zones provide preliminary support that upper mesophotic habitats at FGBNMS have the capacity to serve as refugia for the shallow-water reefs. Diving surveys of the upper mesophotic and shallow-water coral reef have revealed valuable information concerning the reef fish community in the northern Gulf of Mexico, with implications for the conservation of apex predators, oceanic coral reefs, and the future management of FGBNMS. PMID:29161314

Spatial Distribution of Seismic Anisotropy in the Crust in the Northeast Front Zone of Tibetan Plateau

NASA Astrophysics Data System (ADS)

Gao, Y.; Wang, Q.; SHI, Y.

2017-12-01

There are orogenic belts and strong deformation in northeastern zone of Tibetan Plateau. The media in crust and in the upper mantle are seismic anisotropic there. This study uses seismic records by permanent seismic stations and portable seismic arrays, and adopts analysis techniques on body waves to obtain spatial anisotropic distribution in northeastern front zone of Tibetan Plateau. With seismic records of small local earthquakes, we study shear-wave splitting in the upper crust. The polarization of fast shear wave (PFS) can be obtained, and PFS is considered parallel to the strike of the cracks, as well as the direction of maximum horizontal compressive stress. However, the result shows the strong influence from tectonics, such as faults. It suggests multiple-influence including stress and fault. Spatial distribution of seismic anisotropy in study zone presents the effect in short range. PFS at the station on the strike-slip fault is quite different to PFS at station just hundreds of meters away from the fault. With seismic records of teleseismic waveforms, we obtained seismic anisotropy in the whole crust by receiver functions. The PFS directions from Pms receiver functions show consistency, generally in WNW. The time-delay of slow S phases is significant. With seismic records of SKS, PKS and SKKS phases, we can detect seismic anisotropy in the upper mantle by splitting analysis. The fast directions of these phases also show consistency, generally in WNW, similar to those of receiver functions, but larger time-delays. It suggests significant seismic anisotropy in the crust and crustal deformation is coherent to that in the upper mantle.Seismic anisotropy in the upper crust, in the whole crust and in the upper mantle are discussed both in difference and tectonic implications [Grateful to the support by NSFC Project 41474032].

Fracture properties from tight reservoir outcrop analogues with application to geothermal exploration

NASA Astrophysics Data System (ADS)

Philipp, Sonja L.; Reyer, Dorothea; Afsar, Filiz; Bauer, Johanna F.; Meier, Silke; Reinecker, John

2015-04-01

In geothermal reservoirs, similar to other tight reservoirs, fluid flow may be intensely affected by fracture systems, in particular those associated with fault zones. When active (slipping) the fault core, that is, the inner part of a fault zone, which commonly consists of breccia or gouge, can suddenly develop high permeability. Fault cores of inactive fault zones, however, may have low permeabilities and even act as flow barriers. In the outer part of a fault zone, the damage zone, permeability depends mainly on the fracture properties, that is, the geometry (orientation, aperture, density, connectivity, etc.) of the fault-associated fracture system. Mineral vein networks in damage zones of deeply eroded fault zones in palaeogeothermal fields demonstrate their permeability. In geothermal exploration, particularly for hydrothermal reservoirs, the orientation of fault zones in relation to the current stress field as well as their internal structure, in particular the properties of the associated fracture system, must be known as accurately as possible for wellpath planning and reservoir engineering. Here we present results of detailed field studies and numerical models of fault zones and associated fracture systems in palaeogeo¬thermal fields and host rocks for geothermal reservoirs from various stratigraphies, lithologies and tectonic settings: (1) 74 fault zones in three coastal sections of Upper Triassic and Lower Jurassic age (mudstones and limestone-marl alternations) in the Bristol Channel Basin, UK. (2) 58 fault zones in 22 outcrops from Upper Carboniferous to Upper Cretaceous in the Northwest German Basin (siliciclastic, carbonate and volcanic rocks); and (3) 16 fault zones in 9 outcrops in Lower Permian to Middle Triassic (mainly sandstone and limestone) in the Upper Rhine Graben shoulders. Whereas (1) represent palaeogeothermal fields with mineral veins, (2) and (3) are outcrop analogues of reservoir horizons from geothermal exploration. In the study areas of palaeo¬geothermal fields in the Bristol Channel (1), all mineral veins, most of which are extension fractures, are of calcite. They are clearly associated with the faults and indicate that geothermal water was transported along the then-active faults into the host rocks with evidence of injection as hydrofractures. Layers with contrasting mechanical properties (in particular, stiffnesses), however, acted as stress barriers and lead to fracture arrest. Along some faults, veins propagated through the barriers along faults to shallower levels. In the Northwest German Basin (2) there are pronounced differences between normal-fault zones in carbonate and clastic rocks. Only in carbonate rocks clear damage zones occur, characterized by increased fracture frequencies and high amounts of fractures with large apertures. On the Upper Rhine Graben shoulders (3) damage zones in Triassic Muschelkalk limestones are well developed; fault cores are narrow and comprise breccia, clay smear, host rock lenses and mineralization. A large fault zone in Triassic Bunter sandstone shows a clearly developed fault core with fault gouge, slip zones, deformation bands and host rock lenses, a transition zone with mostly disturbed layering and highest fracture frequency, and a damage zone. The latter damage zone is compared to the damage zone of a large Bunter sandstone fault zone currently explored for geothermal energy production. The numerical models focus on stress field development, fracture propagation and associated permeability changes. These studies contribute to the understanding of the hydromechanical behaviour of fault zones and related fluid transport in fractured reservoirs complementing predictions based on geophysical measurements. Eventually we aim at classifying and quantifying fracture system properties in fault zones to improve exploration and exploitation of geothermal reservoirs. Acknowledgements The authors appreciate the support of 'Niedersächsisches Ministerium für Wissen¬schaft und Kultur' and 'Baker Hughes' within the gebo research project (http://www.gebo-nds.de), the Bundesministerium für Umwelt, Naturschutz, Bau und Reaktorsicherheit (BMU; FKZ: 0325302, AuGE) and the Deutsche Forschungsgemeinschaft. GeoEnergy GmbH, Karlsruhe, is thanked for explorational data.

Molecular characters of melon (Cucumismelo L. "Tacapa") in response to karst critical land

NASA Astrophysics Data System (ADS)

Rachmawati, Yuanita; Daryono, Budi Setiadi; Aristya, Ganies Riza

2017-06-01

Yogyakarta district has 158.600 ha critical land and spread off in three Agro Ecosystem zones. Two of them are karsts critical land. Critical lands which contain calcium carbonate in high concentration and water dehydration in upper surface give abiotic stress in wide range of plant. Melon cultivar TACAPA has superior characteristic derived from parental crossing, ♀ Action 434 and ♂ PI 371795 and potential to be developed in karsts critical land. Abscicic acid (ABA) is a phytohormone expressed by plant in abiotic stress condition. CmBG1 is a gene which regulate ABA hormone in melon. The purposes of this research were examining the molecular character of melon cultivar TACAPA in response to karsts critical land in order to study molecular characterization of CmBG1 gene. Analysis was done qualitatively by using Reverse Transcriptase-PCR (RT-PCR) and Electrophoresis, while quantitative analysis was conducted by observing absorbance score in spectrophotometer. CmBG1 gene expression is examined by using Real time PCR (qPCR). Molecular characters obtained are CmBG1 detected in size ±1258 bp, CmBG1 gene concentrations in melon which planted in control media are lower than melon in critical lands media. These results are similar with the real time quantitative analysis method. It also be revealed that melon TACAPA is more potential plant compared to another cultivar that can be developed in karst critical land area.

Burnable absorber arrangement for fuel bundle

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

Crowther, R.L.; Townsend, D.B.

1986-12-16

This patent describes a boiling water reactor core whose operation is characterized by a substantial proportion of steam voids with concomitantly reduced moderation toward the top of the core when the reactor is in its hot operating condition. The reduced moderation leads to slower burnup and greater conversion ratio in an upper core region so that when the reactor is in its cold shut down condition the resulting relatively increased moderation in the upper core region is accompanied by a reactivity profile that peaks in the upper core region. A fuel assembly is described comprising; a component of fissile materialmore » distributed over a substantial axial extent of the fuel assembly; and a component of neutron absorbing material having an axial distribution characterized by an enhancement in an axial zone of the fuel assembly, designated the cold shutdown control zone, corresponding to at least a portion of the axial region of the core when the cold shutdown reactivity peaks. The aggregate amount of neutron absorbing material in the cold shutdown zone of the fuel assembly is greater than the aggregate amount of neutron absorbing material in the axial zones of the fuel assembly immediately above and immediately below the cold shutdown control zone whereby the cold shutdown reactivity peak is reduced relative to the cold shutdown reactivity in the zones immediately above and immediately below the cold shutdown control zone. The cold shutdown zone has an axial extent measured from the bottom of the fuel assembly in the range between 68-88 percent of the height of the fissile material in the fuel assembly.« less

How many upper Eocene microspherule layers: More than we thought

NASA Technical Reports Server (NTRS)

Hazel, Joseph E.

1988-01-01

The scientific controversy over the origin of upper Eocene tektites, microtektites and other microspherules cannot be logically resolved until it is determined just how many events are involved. The microspherule-bearing beds in marine sediments have been dated using standard biozonal techniques. Although a powerful stratigraphic tool, zonal biostratigraph has its limitations. One is that if an event, such as a microspherule occurrence, is observed to occur in a zone at one locality and then a similar event observed in the same zone at another locality, it still may be unwarranted to conclude that these events exactly correlate. To be in a zone a sample only need be between the fossil events that define the zone boundaries. It is often very difficult to accurately determine where within a zone one might be. Further, the zone defining events do not everywhere occur at the same points in time. That is, the ranges of the defining taxa are not always filled. Thus, the length of time represented by a zone (but not, of course, its chronozone) can vary from place to place. These problems can be offset by use of chronostratigraphic modelling techniques such as Graphic Correlation. This technique was used to build a Cretaceous and Cenozoic model containing fossil, magnetopolarity, and other events. The scale of the model can be demonstrated to be linear with time. This model was used to determine the chronostratigraphic position of upper Eocene microspherule layers.

Local extirpations and regional declines of endemic upper beach invertebrates in southern California

NASA Astrophysics Data System (ADS)

Hubbard, D. M.; Dugan, J. E.; Schooler, N. K.; Viola, S. M.

2014-10-01

Along the world's highly valued and populous coastlines, the upper intertidal zones of sandy beach ecosystems and the biodiversity that these zones support are increasingly threatened by impacts of human activities, coastal development, erosion, and climate change. The upper zones of beaches typically support invertebrates with restricted distributions and dispersal, making them particularly vulnerable to habitat loss and fragmentation. We hypothesized that disproportionate loss or degradation of these zones in the last century has resulted in declines of upper shore macroinvertebrates in southern California. We identified a suite of potentially vulnerable endemic upper beach invertebrates with direct development, low dispersal and late reproduction. Based on the availability of printed sources and museum specimens, we investigated historical changes in distribution and abundance of two intertidal isopod species (Tylos punctatus, Alloniscus perconvexus) in southern California. Populations of these isopods have been extirpated at numerous historically occupied sites: T. punctatus from 16 sites (57% decrease), and A. perconvexus from 14 sites (64% decrease). During the same period, we found evidence of only five colonization events. In addition, the northern range limit of the southern species, T. punctatus, moved south by 31 km (8% of range on California mainland) since 1971. Abundances of T. punctatus have declined on the mainland coast; only three recently sampled populations had abundances >7000 individuals m-1. For A. perconvexus populations, abundances >100 individuals m-1 now appear to be limited to the northern part of the study area. Our results show that numerous local extirpations of isopod populations have resulted in regional declines and in greatly reduced population connectivity in several major littoral cells of southern California. Two of the six major littoral cells (Santa Barbara and Zuma) in the area currently support 74% of the remaining isopod populations. These isopods persist primarily on relatively remote, ungroomed, unarmored beaches with restricted vehicle access and minimal management activity. These predominantly narrow, bluff-backed beaches also support species-rich upper beach assemblages, suggesting these isopods can be useful indicators of biodiversity. The high extirpation rates of isopod populations on the southern California mainland over the last century provide a compelling example of the vulnerability of upper beach invertebrates to coastal urbanization. Climate change and sea level rise will exert further pressures on upper beach zones and biota in southern California and globally. In the absence of rapid implementation of effective conservation strategies, our results suggest many upper intertidal invertebrate species are at risk.

Dense lower crust elevates long-term earthquake rates in the New Madrid seismic zone

USGS Publications Warehouse

Levandowski, William Brower; Boyd, Oliver; Ramirez-Guzman, Leonardo

2016-01-01

Knowledge of the local state of stress is critical in appraising intraplate seismic hazard. Inverting earthquake moment tensors, we demonstrate that principal stress directions in the New Madrid seismic zone (NMSZ) differ significantly from those in the surrounding region. Faults in the NMSZ that are incompatible with slip in the regional stress field are favorably oriented relative to local stress. We jointly analyze seismic velocity, gravity, and topography to develop a 3-D crustal and upper mantle density model, revealing uniquely dense lower crust beneath the NMSZ. Finite element simulations then estimate the stress tensor due to gravitational body forces, which sums with regional stress. The anomalous lower crust both elevates gravity-derived stress at seismogenic depths in the NMSZ and rotates it to interfere more constructively with far-field stress, producing a regionally maximal deviatoric stress coincident with the highest concentration of modern seismicity. Moreover, predicted principal stress directions mirror variations (observed independently in moment tensors) at the NMSZ and across the region.

Evidence for an upper mantle low velocity zone beneath the southern Basin and Range-Colorado Plateau transition zone

USGS Publications Warehouse

Benz, H.M.; McCarthy, J.

1994-01-01

A 370-km-long seismic refraction/wide-angle reflection profile recorded during the Pacific to Arizona Crustal Experiment (PACE) detected an upper mantle P-wave low-velocity zone (LVZ) in the depth range 40 to 55 km beneath the Basin and Range in southern Arizona. Interpretation of seismic data places constraints on the sub-crustal lithosphere of the southern Basin and Range Province, which is important in light of the active tectonics of the region and the unknown role of the sub-crustal lithosphere in the development of the western United States. Forward travel time and synthetic seismogram techniques are used to model this shallow upper mantle LVZ. Modeling results show that the LVZ is defined by a 5% velocity decrease relative to a Pn velocity of 7.95 km s−1, suggesting either a ∼3–5% mafic partial melt or high-temperature, sub-solidus peridotite.

Seismicity in the platform regions of Ukraine in the zones of anomalous electrical conductivity

NASA Astrophysics Data System (ADS)

Kushnir, A. N.; Kulik, S. N.; Burakhovich, T. K.

2013-05-01

It is established for the first time that there are several regions in Ukraine, in which the earthquakes occurring within platform territory are correlated to the anomalous conductive structures in the Earth's crust and upper mantle. These regions are identified as (1) Donbass and the eastern part of the Dnieper-Donetsk Depression (DDD); (2) eastern margin of the Ingulets-Krivoi Rog suture zone in the area of the Krivoi Rog-Kremenchug fault zone; (3) the western part of the Cis-Azov megablock; (4) the western boundary of the Ukrainian Shield and its slope; (5) North Dobruja and Pre-Dobrujan Depression. The reconstructed tree-dimensional (3D) geoelectrical models of the Earth's crust and upper mantle feature anomalously low values of electric resistivity. The earthquake sources in the platform areas of Ukraine are localized above the top and in the upper parts of the crustal anomalies of electrical conductivity.

Paleogeographic implications of an erosional remnant of Paleogene rocks southwest of the Sur-Nacimiento Fault Zone, southern Coast Ranges, California

USGS Publications Warehouse

Vedder, J.G.; McLean, H.; Stanley, R.G.; Wiley, T.J.

1991-01-01

A small tract of heretofore-unrecognized Paleogene rocks lies about 30 km northeast of Santa Maria and 1 km southwest of the Sur-Nacimiento fault zone near upper Pine Creek. This poorly exposed assemblage of rocks is less than 50 m thick, lies unconformably on regionally distributed Upper Cretaceous submarine-fan deposits, and consists of three units: fossiliferous lower Eocene mudstone, Oligocene(?) conglomerate, and basaltic andesite that has a radiometric age of 26.6 ?? 0.5 Ma. Both the sedimentary and igneous constituents in the Paleogene sequence are unlike those of known sequences on either side of the Sur-Nacimiento fault zone. The Paleogene sedimentary rocks near upper Pine Creek presumably are remnants of formerly widespread early Eocene bathyal deposits and locally distributed Oligocene(?) fluvial deposits southwest of the fault zone. The 26.6 Ma basaltic andesite, however, may not have extended much beyond its present outcrops. An episode of Oligocene(?) displacement is required by the contrast in thicknesses, depositional patterns, and paleobathymetry of the juxtaposed rock sequences. -from Authors

The pectinate zone is stiff and the arcuate zone determines passive basilar membrane mechanics in the gerbil

NASA Astrophysics Data System (ADS)

Xia, Hongyi; Steele, Charles R.; Puria, Sunil

2018-05-01

The gerbil basilar membrane (BM) differs from other mammalian BMs in that the lower collagen-fiber layer of the pectinate zone (PZ) forms an arch, the upper fiber layer is flat, and ground substance separates the two layers. The role of this arch has been unknown, but can be elucidated by models. In the standard simple beam model (SBM), the upper and lower collagen-fiber layers of the BM are represented as a single layer in both the PZ and the arcuate zone (AZ). In our new arch-beam model (ABM), the upper fiber layer is flat, the lower layer forms an arch in the PZ, and the two layers combine to form the flat portion of the BM in the AZ. This design is incorporated into a 3D finite-element tapered-box model of the cochlea with viscous fluid. We find in the model that the PZ rotates as a rigid body, so its specific properties have little influence, while the AZ thickness and collagen volume fraction primarily determine passive BM mechanics.

Crystal accumulation and compositional trends in a calc-alkaline batholith: implications for correlation of plutonic and volcanic rocks

NASA Astrophysics Data System (ADS)

Barnes, C. G.; Coint, N.

2013-12-01

The Wooley Creek batholith is a tilted, calc-alkaline intrusive complex in the Klamath Mountain province, California, that can be divided into two main zones: lower (~159.2 × 0.2 Ma) and upper (~158.2 × 0.3 Ma), separated by a central transition zone. The lower zone consists of multiple intrusive units of gabbro through tonalite, with minor mafic synplutonic dikes and intrusive melagabbro and pyroxenite. Major and trace element data plot in two groups: a mafic group that encompasses pyroxenite to diorite, and a tonalitic group. For each group, Mg/Fe in augite was used to determine the approximate composition of equilibrium melt and then major element mass balance was used to calculate proportions of cumulate phases and melt. For the mafic group, no single parental magma can be identified, which is consistent with assembly via many magma batches. However, the most mafic rocks were derived from basaltic andesite magmas and represent 30 to 100% cumulate augite + opx × plagioclase × olivine. Interstitial melt in the tonalitic group was dacitic, and mass balance indicates from 30 to 80% cumulate pyroxenes + plagioclase × accessory apatite and Fe-Ti oxides. The parental magma was probably silicic andesite. The upper zone varies gradationally from structurally low quartz diorite to uppermost granite. Upper zone magmas ';leaked' to form dacitic to rhyodacitic ';roof dikes'. Previous work (Coint et al., Geosphere, in press) showed that the upper zone formed from an approximately homogeneous magma body and that compositional variation was related to upward percolation of melt. Mass balance supports this interpretation and indicates that (1) the parental magmas were andesitic, (2) structurally low rocks are 15 to 65 % cumulate hornblende + plagioclase × pyroxene, and (3) high-level granite and granodiorite are the fractionated products of this accumulation. These results show that the upper zone is a good example of fractional crystallization within a moderate-sized magma body (≥ 160 km3) in which both cumulates and differentiates are readily identified. In contrast, differentiates related to lower-zone cumulate rocks are rare, presumably because they intruded higher crustal levels and/or erupted. We conclude that compositional trends of lower-zone rocks are dominated by crystal accumulation and do not accurately reflect magmatic evolution owing to loss of differentiated magmas. If this process is common in such plutons, then the use of bulk-rock compositions to identify consanguineous plutonic and volcanic rocks will be difficult, at best.

Validation of Body Volume Acquisition by Using Elliptical Zone Method.

PubMed

Chiu, C-Y; Pease, D L; Fawkner, S; Sanders, R H

2016-12-01

The elliptical zone method (E-Zone) can be used to obtain reliable body volume data including total body volume and segmental volumes with inexpensive and portable equipment. The purpose of this research was to assess the accuracy of body volume data obtained from E-Zone by comparing them with those acquired from the 3D photonic scanning method (3DPS). 17 male participants with diverse somatotypes were recruited. Each participant was scanned twice on the same day by a 3D whole-body scanner and photographed twice for the E-Zone analysis. The body volume data acquired from 3DPS was regarded as the reference against which the accuracy of the E-Zone was assessed. The relative technical error of measurement (TEM) of total body volume estimations was around 3% for E-Zone. E-Zone can estimate the segmental volumes of upper torso, lower torso, thigh, shank, upper arm and lower arm accurately (relative TEM<10%) but the accuracy for small segments including the neck, hand and foot were poor. In summary, E-Zone provides a reliable, inexpensive, portable, and simple method to obtain reasonable estimates of total body volume and to indicate segmental volume distribution. © Georg Thieme Verlag KG Stuttgart · New York.

Least-cost control of agricultural nutrient contributions to the Gulf of Mexico hypoxic zone

USDA-ARS?s Scientific Manuscript database

In 2007, the hypoxic zone in the Gulf of Mexico, measuring 20,720 km**2, was one of the two largest reported since measurement of the zone began in 1985. The extent of the hypoxic zone is related to nitrogen and phosphorous loadings originating on agricultural fields in the upper Midwest. This stud...

Comparative velocity structure of active Hawaiian volcanoes from 3-D onshore-offshore seismic tomography

USGS Publications Warehouse

Park, J.; Morgan, J.K.; Zelt, C.A.; Okubo, P.G.; Peters, L.; Benesh, N.

2007-01-01

We present a 3-D P-wave velocity model of the combined subaerial and submarine portions of the southeastern part of the Island of Hawaii, based on first-arrival seismic tomography of marine airgun shots recorded by the onland seismic network. Our model shows that high-velocity materials (6.5-7.0??km/s) lie beneath Kilauea's summit, Koae fault zone, and the upper Southwest Rift Zone (SWRZ) and upper and middle East Rift Zone (ERZ), indicative of magma cumulates within the volcanic edifice. A separate high-velocity body of 6.5-6.9??km/s within Kilauea's lower ERZ and upper Puna Ridge suggests a distinct body of magma cumulates, possibly connected to the summit magma cumulates at depth. The two cumulate bodies within Kilauea's ERZ may have undergone separate ductile flow seaward, influencing the submarine morphology of Kilauea's south flank. Low velocities (5.0-6.3??km/s) seaward of Kilauea's Hilina fault zone, and along Mauna Loa's seaward facing Kao'iki fault zone, are attributed to thick piles of volcaniclastic sediments deposited on the submarine flanks. Loihi seamount shows high-velocity anomalies beneath the summit and along the rift zones, similar to the interpreted magma cumulates below Mauna Loa and Kilauea volcanoes, and a low-velocity anomaly beneath the oceanic crust, probably indicative of melt within the upper mantle. Around Kilauea's submarine flank, a high-velocity anomaly beneath the outer bench suggests the presence of an ancient seamount that may obstruct outward spreading of the flank. Mauna Loa's southeast flank is also marked by a large, anomalously high-velocity feature (7.0-7.4??km/s), interpreted to define an inactive, buried volcanic rift zone, which might provide a new explanation for the westward migration of Mauna Loa's current SWRZ and the growth of Kilauea's SWRZ. ?? 2007 Elsevier B.V. All rights reserved.

Hydration-reduced lattice thermal conductivity of olivine in Earth’s upper mantle

PubMed Central

Chang, Yun-Yuan; Hsieh, Wen-Pin; Tan, Eh; Chen, Jiuhua

2017-01-01

Earth’s water cycle enables the incorporation of water (hydration) in mantle minerals that can influence the physical properties of the mantle. Lattice thermal conductivity of mantle minerals is critical for controlling the temperature profile and dynamics of the mantle and subducting slabs. However, the effect of hydration on lattice thermal conductivity remains poorly understood and has often been assumed to be negligible. Here we have precisely measured the lattice thermal conductivity of hydrous San Carlos olivine (Mg0.9Fe0.1)2SiO4 (Fo90) up to 15 gigapascals using an ultrafast optical pump−probe technique. The thermal conductivity of hydrous Fo90 with ∼7,000 wt ppm water is significantly suppressed at pressures above ∼5 gigapascals, and is approximately 2 times smaller than the nominally anhydrous Fo90 at mantle transition zone pressures, demonstrating the critical influence of hydration on the lattice thermal conductivity of olivine in this region. Modeling the thermal structure of a subducting slab with our results shows that the hydration-reduced thermal conductivity in hydrated oceanic crust further decreases the temperature at the cold, dry center of the subducting slab. Therefore, the olivine−wadsleyite transformation rate in the slab with hydrated oceanic crust is much slower than that with dry oceanic crust after the slab sinks into the transition zone, extending the metastable olivine to a greater depth. The hydration-reduced thermal conductivity could enable hydrous minerals to survive in deeper mantle and enhance water transportation to the transition zone. PMID:28377520

A deep crustal fluid channel into the San Andreas Fault system near Parkfield, California

USGS Publications Warehouse

Becken, M.; Ritter, O.; Park, S.K.; Bedrosian, P.A.; Weckmann, U.; Weber, M.

2008-01-01

Magnetotelluric (MT) data from 66 sites along a 45-km-long profile across the San Andreas Fault (SAF) were inverted to obtain the 2-D electrical resistivity structure of the crust near the San Andreas Fault Observatory at Depth (SAFOD). The most intriguing feature of the resistivity model is a steeply dipping upper crustal high-conductivity zone flanking the seismically defined SAF to the NE, that widens into the lower crust and appears to be connected to a broad conductivity anomaly in the upper mantle. Hypothesis tests of the inversion model suggest that upper and lower crustal and upper-mantle anomalies may be interconnected. We speculate that the high conductivities are caused by fluids and may represent a deep-rooted channel for crustal and/or mantle fluid ascent. Based on the chemical analysis of well waters, it was previously suggested that fluids can enter the brittle regime of the SAF system from the lower crust and mantle. At high pressures, these fluids can contribute to fault-weakening at seismogenic depths. These geochemical studies predicted the existence of a deep fluid source and a permeable pathway through the crust. Our resistivity model images a conductive pathway, which penetrates the entire crust, in agreement with the geochemical interpretation. However, the resistivity model also shows that the upper crustal branch of the high-conductivity zone is located NE of the seismically defined SAF, suggesting that the SAF does not itself act as a major fluid pathway. This interpretation is supported by both, the location of the upper crustal high-conductivity zone and recent studies within the SAFOD main hole, which indicate that pore pressures within the core of the SAF zone are not anomalously high, that mantle-derived fluids are minor constituents to the fault-zone fluid composition and that both the volume of mantle fluids and the fluid pressure increase to the NE of the SAF. We further infer from the MT model that the resistive Salinian block basement to the SW of the SAFOD represents an isolated body, being 5-8km wide and reaching to depths >7km, in agreement with aeromagnetic data. This body is separated from a massive block of Salinian crust farther to the SW. The NE terminus of resistive Salinian crust has a spatial relationship with a near-vertical zone of increased seismic reflectivity ???15km SW of the SAF and likely represents a deep-reaching fault zone. ?? 2008 The Authors Journal compilation ?? 2008 RAS.

Summary of hydrologic testing of the Floridan aquifer system at Hunter Army Airfield, Chatham County, Georgia

USGS Publications Warehouse

Williams, Lester J.

2010-01-01

A 1,168-foot deep test well was completed at Hunter Army Airfield in the summer of 2009 to investigate the potential of using the Lower Floridan aquifer as a source of water supply to satisfy increased needs as a result of base expansion and increased troop levels. The U.S. Geological Survey conducted hydrologic testing at the test site including flowmeter surveys, packer-slug tests, and aquifer tests of the Upper and Lower Floridan aquifers. Flowmeter surveys were completed at different stages of well construction to determine the depth and yield of water-bearing zones and to identify confining beds that separate the main producing aquifers. During a survey when the borehole was open to both the upper and lower aquifers, five water-bearing zones in the Upper Floridan aquifer supplied 83.5 percent of the total pumpage, and five water-bearing zones in the Lower Floridan aquifer supplied the remaining 16.5 percent. An upward gradient was indicated from the ambient flowmeter survey: 7.6 gallons per minute of groundwater was detected entering the borehole between 750 and 1,069 feet below land surface, then moved upward, and exited the borehole into lower-head zones between 333 and 527 feet below land surface. During a survey of the completed Lower Floridan well, six distinct water-producing zones were identified; one 17-foot-thick zone at 768-785 feet below land surface yielded 47.9 percent of the total pumpage while the remaining five zones yielded between 2 and 15 percent each. The thickness and hydrologic properties of the confining unit separating the Upper and Lower Floridan aquifers were determined from packer tests and flowmeter surveys. This confining unit, which is composed of rocks of Middle Eocene age, is approximately 160 feet thick with horizontal hydraulic conductivities determined from four slug tests to range from 0.2 to 3 feet per day. Results of two separate slug tests within the middle confining unit were both 2 feet per day. Aquifer testing indicated the Upper Floridan aquifer had a transmissivity of 40,000 feet squared per day, and the Lower Floridan aquifer had a transmissivity of 10,000 feet squared per day. An aquifer test conducted on the combined aquifer system, when the test well was open from 333 to 1,112 feet, gave a transmissivity of 50,000 feet squared per day. Additionally, during the 72-hour test of the Lower Floridan aquifer, a drawdown response was observed in the Upper Floridan aquifer wells.

Triggering effect of mining at different horizons in the rock mass with excavations. Mathematical modeling

NASA Astrophysics Data System (ADS)

Eremin, M. O.; Makarov, P. V.

2017-12-01

On the basis of a quite simple structural model of rock mass, containing coal seams on two horizons, coal mining is numerically modeled. A finite difference numerical technique is applied. At first, mining starts at the upper horizon and then moves to the lower horizon. It is shown that a mining process at the lower horizon has a significant triggering influence on the growth of damage zones in the roof and floor at the upper horizon. The features of spatiotemporal migration of deformation activity are studied numerically. Foci of large-scale fracture are located at the boundary of the seismic silence zone and the zone where the deformation activity migrates. This boundary has an additional characteristic: the maximum gradient of rock pressure is observed in this zone.

Concentration-Discharge Relations in the Critical Zone: Implications for Resolving Critical Zone Structure, Function, and Evolution

NASA Astrophysics Data System (ADS)

Chorover, Jon; Derry, Louis A.; McDowell, William H.

2017-11-01

Critical zone science seeks to develop mechanistic theories that describe critical zone structure, function, and long-term evolution. One postulate is that hydrogeochemical controls on critical zone evolution can be inferred from solute discharges measured down-gradient of reactive flow paths. These flow paths have variable lengths, interfacial compositions, and residence times, and their mixing is reflected in concentration-discharge (C-Q) relations. Motivation for this special section originates from a U.S. Critical Zone Observatories workshop that was held at the University of New Hampshire, 20-22 July 2015. The workshop focused on resolving mechanistic CZ controls over surface water chemical dynamics across the full range of lithogenic (e.g., nonhydrolyzing and hydrolyzing cations and oxyanions) and bioactive solutes (e.g., organic and inorganic forms of C, N, P, and S), including dissolved and colloidal species that may cooccur for a given element. Papers submitted to this special section on "concentration-discharge relations in the critical zone" include those from authors who attended the workshop, as well as others who responded to the open solicitation. Submissions were invited that utilized information pertaining to internal, integrated catchment function (relations between hydrology, biogeochemistry, and landscape structure) to help illuminate controls on observed C-Q relations.

The Devils Mountain Fault zone: An active Cascadia upper plate zone of deformation, Pacific Northwest of North America

NASA Astrophysics Data System (ADS)

Barrie, J. Vaughn; Greene, H. Gary

2018-02-01

The Devils Mountain Fault Zone (DMFZ) extends east to west from Washington State to just south of Victoria, British Columbia, in the northern Strait of Juan de Fuca of Canada and the USA. Recently collected geophysical data were used to map this fault zone in detail, which show the main fault trace, and associated primary and secondary (conjugate) strands, and extensive northeast-southwest oriented folding that occurs within a 6 km wide deformation zone. The fault zone has been active in the Holocene as seen in the offset and disrupted upper Quaternary strata, seafloor displacement, and deformation within sediment cores taken close to the seafloor expression of the faults. Data suggest that the present DMFZ and the re-activated Leech River Fault may be part of the same fault system. Based on the length and previously estimated slip rates of the fault zone in Washington State, the DMFZ appears to have the potential of producing a strong earthquake, perhaps as large as magnitude 7.5 or greater, within 2 km of the city of Victoria.

Preliminary appraisal of the geohydrologic aspects of drainage wells, Orlando area, central Florida

USGS Publications Warehouse

Kimrey, Joel O.

1978-01-01

The Floridan aquifer contains two highly transmissive cavernous zones in the Orlando area: an upper producing zone about 150-600 feet below land surface; and a lower producing zone about 1,100-1,500 feet below land surface. Natural head differences are downward and there is hydraulic connection between the two producing zones. Drainage wells are finished open-end into the upper producing zone and emplace surface waters directly into that zone by gravity. Quantitatively, their use constitutes an effective method of artificial recharge. Their negative aspects relate to the probably poor, but unknown, quality of the recharge water. Caution is suggested in drawing definite and final conclusions on the overall geohydrologic and environmental effects of drainage wells prior to the collection and interpretation of a considerable quantity of new data. Though few ground-water pollution problems have been documented to date, the potential for such pollution should be seriously considered in light of the prob-able continuing need to use drainage wells; the probable volumes and quality of water involved; and the hydraulic relations between the two producing zones.

Cretaceous planktic foraminiferal biostratigraphy of the Calera Limestone, Northern California, USA

USGS Publications Warehouse

Sliter, W.V.

1999-01-01

The Calera Limestone is the largest, most stratigraphically extensive limestone unit of oceanic character included in the Franciscan Complex of northern California. The aim of this paper is to place the Calera Limestone at its type locality (Rockaway Beach, Pacifica) in a high-resolution biostratigraphy utilizing planktic foraminifers studied in thin section. A section, about 110 m-thick, was measured from the middle thrust slice exposed by quarrying on the southwest side of Calera Hill at Pacifica Quarry. Lithologically, the section is divided in two units; a lower unit with 73 m of black to dark-grey limestone, black chert and tuff, and an upper unit with 36.8 m of light-grey limestone and medium-grey chert. Two prominent black-shale layers rich in organic carbon occur 11 m below the top of the lower black unit and at the boundary with overlying light-grey unit, yielding a total organic content (TOC) of 4.7% and 1.8% t.w., respectively. The fossiliferous Calera Limestone section measured at Pacifica Quarry, from the lower black shale, contains eleven zones and three subzones that span approximately 26 m.y. from the early Aptian to the late Cenomanian. The zones indentified range from the Globigerinelloides blowi Zone to the Dicarinella algeriana Subzone of the Rotalipora cushmani Zone. Within this biostratigraphic interval, the Ticinella bejaouaensis and Hedbergella planispira Zones at the Aptian/Albian boundary are missing as are the Rotalipora subticinensis Subzone of the Biticinella breggiensis Zone and the overlying Rotalipora ticinensis Zone in the late Albian owing both to low-angle thrust faulting and to unconformities. The abundance and preservation of planktic foraminifers are poor in the lower part and improve only within the upper G. algerianus Zone. The faunal relationship indicate that the lower black shale occurs in the upper part of the G. blowi Zone and correlates with the Selli Event recognized at global scale in the early Aptian. The upper black shale occurs at or near the boundary between the G. ferreolensis and G. algerianus Zone in the late Aptian. This black layer, or Thalmann Event as named here, seems to represent the sedimentary expression, at the scale of Permanente Terrane, of a global perturbation of the carbon cycle.

Sandbox Simulations of the Evolution of a Subduction Wedge following Subduction Initiation

NASA Astrophysics Data System (ADS)

Brandon, M. T.; Ma, K. F.; DeWolf, W.

2012-12-01

Subduction wedges at accreting subduction zones are bounded by a landward dipping pro-shear zone (= subduction thrust) and a seaward-dipping retro-shear zone in the overriding plate. For the Cascadia subduction zone, the surface trace of the retro-shear zone corresponds to the east side of the Coast Ranges of Oregon and Washington and the Insular Mountains of Vancouver Island. This coastal high or forearc high shows clear evidence of long-term uplift and erosion along its entire length, indicating that it is an active part of the Cascadia subduction wedge. The question addressed here is what controls the location of the retro-shear zone? In the popular double-sided wedge model of Willet et al (Geology 1993), the retro-shear zone remains pinned to the S point, which is interpreted to represent where the upper-plate Moho intersects the subduction zone. For this interpretation, the relatively strong mantle is considered to operate as a flat backstop. That model, however. is somewhat artificial in that the two plates collide in a symmetric fashion with equal crustal thicknesses on both sides. Using sandbox experiments, we explore a more realistic configuration where the upper and lower plate are separated by a gentle dipping (10 degree) pro-shear zone, to simulate the initial asymmetric geometry of the subduction thrust immediately after initiation of subduction. The entire lithosphere must fail along some plane for subduction to begin and this failure plane must dip in the direction of subduction. Thus, the initial geometry of the overriding plate is better approximated as a tapered wedge than as a layer of uniform thickness, as represented in the Willett et al models. We demonstrate this model using time-lapse movies of a sand wedge above a mylar subducting plate. We use particle image velocimetry (PIV) to show the evolution of strain and structure within the overriding plate. Material accreted to the tapered end of the overriding plate drives deformation and causes the retro-shear zone to propagate rearward with time. The main conclusion is that the rearward propagation will cease only when 1) the retro shear zone reaches the S point (i.e. the mantle cutoff in the upper plate) or 2) the erosion outflux from the subduction wedge matches the accretionary influx. Given the location of the upper plate Moho at Cascadia, it seems that erosion is the control factor in pinning the retro shear zone there.

Lateral Variations of Interplate Coupling along the Mexican Subduction Interface: Relationships with Long-Term Morphology and Fault Zone Mechanical Properties

NASA Astrophysics Data System (ADS)

Rousset, Baptiste; Lasserre, Cécile; Cubas, Nadaya; Graham, Shannon; Radiguet, Mathilde; DeMets, Charles; Socquet, Anne; Campillo, Michel; Kostoglodov, Vladimir; Cabral-Cano, Enrique; Cotte, Nathalie; Walpersdorf, Andrea

2016-10-01

Although patterns of interseismic strain accumulation above subduction zones are now routinely characterised using geodetic measurements, their physical origin, persistency through time, and relationships to seismic hazard and long-term deformation are still debated. Here, we use GPS and morphological observations from southern Mexico to explore potential mechanical links between variations in inter-SSE (in between slow slip events) coupling along the Mexico subduction zone and the long-term topography of the coastal regions from Guerrero to Oaxaca. Inter-SSE coupling solutions for two different geometries of the subduction interface are derived from an inversion of continuous GPS time series corrected from slow slip events. They reveal strong along-strike variations in the shallow coupling (i.e. at depths down to 25 km), with high-coupling zones (coupling >0.7) alternating with low-coupling zones (coupling <0.3). Coupling below the continent is typically strong (>0.7) and transitions to uncoupled, steady slip at a relatively uniform ˜ 175-km inland from the trench. Along-strike variations in the coast-to-trench distances are strongly correlated with the GPS-derived forearc coupling variations. To explore a mechanical explanation for this correlation, we apply Coulomb wedge theory, constrained by local topographic, bathymetric, and subducting-slab slopes. Critical state areas, i.e. areas where the inner subduction wedge deforms, are spatially correlated with transitions at shallow depth between uncoupled and coupled areas of the subduction interface. Two end-member models are considered to explain the correlation between coast-to-trench distances and along-strike variations in the inter-SSE coupling. The first postulates that the inter-SSE elastic strain is partitioned between slip along the subduction interface and homogeneous plastic permanent deformation of the upper plate. In the second, permanent plastic deformation is postulated to depend on frictional transitions along the subduction plate interface. Based on the location and friction values of the critical state areas identified by our Coulomb wedge analysis, we parameterise frictional transitions in plastic-static models of deformation over several seismic cycles. This predicts strong shear dissipation above frictional transitions on the subduction interface. The comparison of modelled surface displacements over a critical zone at a frictional transition and over a stable area with no internal wedge deformation shows differences of long-term uplift consistent with the observed along-strike variations in the coast-to-trench distances. Our work favours a model in which frictional asperities partly control short-term inter-SSE coupling as measured by geodesy and in which those asperities persist through time.

Fabric evolution across a discontinuity between lower and upper crustal domains from field, microscopic, and anisotropy of magnetic susceptibility studies in central eastern Eritrea, NE Africa

NASA Astrophysics Data System (ADS)

Ghebreab, W.; Kontny, A.; Greiling, R. O.

2007-06-01

In the Neoproterozoic East African Orogen (EAO) of Eritrea, lower to middle crustal high-grade metamorphic rocks are juxtaposed against low-grade upper crustal rocks along diffuse tectonic contact zones or discontinuities. In the central eastern part of Eritrea, such a tectonic zone is exposed as a low-angle shear zone separating two distinct high- and low-grade domains, the Ghedem and Bizen, respectively. Integrated field, microfabric, and anisotropy of magnetic susceptibility (AMS) studies show that this low-angle shear zone formed during late deformation, D2, with top-to-the-E/SE sense of motion. The hanging wall upper crustal volcanosedimentary schists are mainly paramagnetic and the footwall middle crustal mylonitized orthogneisses are mainly ferrimagnetic. Magnetic fabric studies revealed a good agreement between metamorphic/mylonitic and magnetic foliations (Kmin) and helped to explain fabric development in the shear zone. The magnetic lineations (Kmax) reflect stretching lineations where stretched mineral aggregates dominate fine-grained mylonitic matrices and intersection lineations where microstructural studies revealed two fabric elements. AMS directional plots indicate that the orientations of the magnetic lineation and of the pole to the magnetic foliation vary systematically across the shear zone. While Kmax axes form two broad maxima oriented approximately N-S and E-W, the Kmin axes change from subhorizontal, generally westward inclination in the west to moderate to steep inclination in the direction of tectonic movement to the east. Because there is a systematic change in inclination of Kmin for individual samples, all samples together form a fairly well defined cluster distribution. The distribution of Kmin in combination with the E-W scattered plot of the Kmax is in accordance with the E/SE flow of mylonites over exhumed Damas core complex in the late Neoproterozoic. During the Cenozoic, the Red Sea rift-related detachments exploited the late orogenic shear zone, indicating that the discontinuities between ductile middle and brittle upper crustal layers in the region are reactivated low-angle shear zones and possible sites of core complexes.

The locations and amounts of endogenous ions and elements in the cap and elongating zone of horizontally oriented roots of Zea mays L.: an electron-probe EDS study

NASA Technical Reports Server (NTRS)

Moore, R.; Cameron, I. L.; Hunter, K. E.; Olmos, D.; Smith, N. K.

1987-01-01

We used quantitative electron-probe energy-dispersive x-ray microanalysis to localize endogenous Na, Cl, K, P, S, Mg and Ca in cryofixed and freeze-dried cryosections of the cap (i.e. the putative site of graviperception) and elongating zone (i.e. site of gravicurvature) of horizontally oriented roots of Zea mays. Ca, Na, Cl, K and Mg accumulate along the lower side of caps of horizontally oriented roots. The most dramatic asymmetries of these ions occur in the apoplast, especially the mucilage. We could not detect any significant differences in the concentrations of these ions in the central cytoplasm of columella cells along the upper and lower sides of caps of horizontally-oriented roots. However, the increased amounts of Na, Cl, K and Mg in the longitudinal walls of columella cells along the lower side of the cap suggest that these ions may move down through the columella tissue of horizontally-oriented roots. Ca also accumulates (largely in the mucilage) along the lower side of the elongating zone of horizontally-oriented roots, while Na, P, Cl and K tend to accumulate along the upper side of the elongating zone. Of these ions, only K increases in concentration in the cytoplasm and longitudinal walls of cortical cells in the upper vs lower sides of the elongating zone. These results indicate that (1) gravity-induced asymmetries of ions differ significantly in the cap and elongating zone of graviresponding roots, (2) Ca accumulates along the lower side of the cap and elongating zone of graviresponding roots, (3) increased growth of the upper side of the elongating zone of horizontally-oriented roots correlates positively with increased amounts of K in the cytoplasm and longitudinal walls of cortical cells, and (4) the apoplast (especially the mucilage) may be an important component of the pathway via which ions move in graviresponding rots of Zea mays. These results are discussed relative to mechanisms for graviperception and gravicurvature of roots.

An analysis of seismic hazard in the Upper Rhine Graben enlightened by the example of the New Madrid seismic zone.

NASA Astrophysics Data System (ADS)

Doubre, Cécile; Masson, Frédéric; Mazzotti, Stéphane; Meghraoui, Mustapha

2014-05-01

Seismic hazard in the "stable" continental regions and low-level deformation zones is one of the most difficult issues to address in Earth sciences. In these zones, instrumental and historical seismicity are not well known (sparse seismic networks, seismic cycle too long to be covered by the human history, episodic seismic activity) and many active structures remain poorly characterized or unknown. This is the case of the Upper Rhine Graben, the central segment of the European Cenozoic rift system (ECRIS) of Oligocene age, which extends from the North Sea through Germany and France to the Mediterranean coast over a distance of some 1100 km. Even if this region has already experienced some destructive earthquakes, its present-day seismicity is moderate and the deformation observed by geodesy is very small (below the current measurement accuracy). The strain rate does not exceed 10-10 and paleoseismic studies indicate an average return period of 2.5 to 3 103 ka for large earthquakes. The largest earthquake known for this zone is the 1356 Basel earthquake, with a magnitude generally estimated about 6.5 (Meghraoui et al., 2001) but recently re-evaluated between 6.7 and 7.1 (Fäh et al et al., 2009). A comparison of the Upper Rhine Graben with equivalent regions around the world could help improve our evaluation of seismic hazard of this region. This is the case of the New Madrid seismic zone, one of the best studied intraplate system in central USA, which experienced an M 7.0 - 7.5 earthquake in 1811-1812 and shares several characteristics with the Upper Rhine Graben, i.e. the general framework of inherited geological structures (reactivation of a failed rift / graben), seismicity patterns (spatial variability of small and large earthquakes), the null or low rate of deformation, and the location in a "stable" continental interior. Looking at the Upper Rhine Graben as an analogue of the New Madrid seismic zone, we can re-evaluate its seismic hazard and consider the possibility of an earthquake of magnitude 7 or greater.

Overview of the magnetic signatures of the Palaeoproterozoic Rustenburg Layered Suite, Bushveld Complex, South Africa

USGS Publications Warehouse

Cole, Janine; Finn, Carol A.; Webb, Susan J.

2013-01-01

Aeromagnetic data clearly delineate the mafic rocks of the economically significant Bushveld Igneous Complex. This is mainly due to the abundance of magnetite in the Upper Zone of the Rustenburg Layered Suite of the Bushveld, but strongly remanently magnetised rocks in the Main Zone also contribute significantly in places. In addition to delineating the extent of the magnetic rocks in the complex, the magnetic anomalies also provide information about the dip and depth of these units. The presence of varying degrees of remanent magnetisation in most of the magnetic lithologies of the Rustenburg Layered Suite complicates the interpretation of the data. The combination of available regional and high resolution airborne magnetic data with published palaeomagnetic data reveals characteristic magnetic signatures associated with the different magnetic lithologies in the Rustenburg Layered Suite. As expected, the ferrogabbros of the Upper Zone cause the highest amplitude magnetic anomalies, but in places subtle features within the Main Zone can also be detected. A marker with strong remanent magnetisation located in the Main Zone close to the contact with the Upper Zone is responsible for very high amplitude negative anomalies in the southern parts of both the eastern and western lobes of the Bushveld Complex. Prominent anomalies are not necessarily related to a specific lithology, but can result from the interaction between anomalies caused by differently magnetised bodies.The magnetic data provided substantial information at different levels of detail, ranging from contacts between zones, and layering within zones, to magnetite pipes dykes and faults that can have an impact on mine planning. Finally, simple modelling of the magnetic data supports the concept of continuous mafic rocks between the western and eastern lobes.

Consequences of Rift Propagation for Spreading in Thick Oceanic Crust in Iceland

NASA Astrophysics Data System (ADS)

Karson, J. A.

2015-12-01

Iceland has long been considered a natural laboratory for processes related to seafloor spreading, including propagating rifts, migrating transforms and rotating microplates. The thick, hot, weak crust and subaerial processes of Iceland result in variations on the themes developed along more typical parts of the global MOR system. Compared to most other parts of the MOR, Icelandic rift zones and transform faults are wider and more complex. Rift zones are defined by overlapping arrays of volcanic/tectonic spreading segments as much as 50 km wide. The most active rift zones propagate N and S away from the Iceland hot spot causing migration of transform faults. A trail of crust deformed by bookshelf faulting forms in their wakes. Dead or dying transform strands are truncated along pseudofaults that define propagation rates close to the full spreading rate of ~20 mm/yr. Pseudofaults are blurred by spreading across wide rift zones and laterally extensive subaerial lava flows. Propagation, with decreasing spreading toward the propagator tips causes rotation of crustal blocks on both sides of the active rift zones. The blocks deform internally by the widespread reactivation of spreading-related faults and zones of weakness along dike margins. The sense of slip on these rift-parallel strike-slip faults is inconsistent with transform-fault deformation. These various deformation features as well as subaxial subsidence that accommodate the thickening of the volcanic upper crustal units are probably confined to the brittle, seismogenic, upper 10 km of the crust. At least beneath the active rift zones, the upper crust is probably decoupled from hot, mechanically weak middle and lower gabbroic crust resulting in a broad plate boundary zone between the diverging lithosphere plates. Similar processes may occur at other types of propagating spreading centers and magmatic rifts.

Inter-Rater Agreement of Auscultation, Palpable Fremitus, and Ventilator Waveform Sawtooth Patterns Between Clinicians.

PubMed

Berry, Marc P; Martí, Joan-Daniel; Ntoumenopoulos, George

2016-10-01

Clinicians often use numerous bedside assessments for secretion retention in participants who are receiving invasive mechanical ventilation. This study aimed to evaluate inter-rater agreement between clinicians when using standard clinical assessments of secretion retention and whether differences in clinician experience influenced inter-rater agreement. Seventy-one mechanically ventilated participants were assessed by a research clinician and by one of 13 ICU clinicians. Each clinician conducted a standardized assessment of lung auscultation, palpation for chest-wall (rhonchal) fremitus, and ventilator inspiratory/expiratory flow-time waveforms for the sawtooth pattern. On the presence of breath sounds, agreement ranged from absolute to moderate in the upper zones and the lower zones, respectively. Kappa values for abnormal and adventitious lung sounds achieved moderate agreement in the upper zones, less than chance agreement to substantial agreement in the middle zones, and moderate agreement to almost perfect agreement in the lower zones. Moderate to almost perfect agreement was established for palpable fremitus in the upper zones, moderate to substantial agreement in the middle zones, and less than chance to moderate agreement in the lower zones. Inter-rater agreement on the presence of expiratory sawtooth pattern identification showed moderate agreement. The level of percentage agreement between the research and ICU clinicians for each respiratory assessment studied did not relate directly to level of clinical experience. Inter-rater agreement for all assessments showed variability between lung regions but maintained reasonable percentage agreement in mechanically ventilated participants. The level of percentage agreement achieved between clinicians did not directly relate to clinical experience for all respiratory assessments. Therefore, these respiratory assessments should not necessarily be viewed in isolation but interpreted within the context of a full clinical assessment. Copyright © 2016 by Daedalus Enterprises.

Biostratigraphy and event stratigraphy in Iran around the Permian Triassic Boundary (PTB): Implications for the causes of the PTB biotic crisis

NASA Astrophysics Data System (ADS)

Kozur, H. W.

2007-01-01

The conodont succession and stratigraphic events around the Permian-Triassic boundary (PTB) have been investigated in detail in the open sea deposits of Iran (Abadeh and Shahreza in central Iran, and Jolfa and Zal in northwestern Iran). This investigation produced a very detailed conodont zonation from the Clarkina nodosa Zone up to the Isarcicella isarcica Zone. All significant events have been accurately located and dated within this zonation, and the duration of most of these conodont zones has been calculated by cross-correlation with continental lake deposits that display obvious Milankovitch cyclicity. The unusually short duration of all conodont zones in the interval from the C. nodosa up to the Hindeodus parvus Zone indicates that there was persistent high ecological stress during this time interval. Most of the conodont zones can be accurately correlated with South China. In the interval from the C. hauschkei Zone to the H. parvus Zone, even correlation with the Arctic is possible. Within three thin stratigraphic intervals, the Changhsingian (Dorashamian) warm water conodont fauna of the C. subcarinata lineage is replaced by a cool water fauna with small H. typicalis, rare Merrillina sp., and cool water Clarkina that have very widely spaced denticles. The uppermost cool water fauna horizon comprises the lower C. zhangi Zone and can be accurately correlated with continental beds by recognition of a short reversed magnetozone below the long uppermost Permian-lowermost Triassic normal magnetozone. In Iran and Transcaucasia, this short reversed zone comprises the upper C. changxingensis- C. deflecta Zone and most of the C. zhangi Zone. Its top lies 50 cm below the top of the Paratirolites Limestone (s.s.) in the Dorasham 2 section, which is at the beginning of the upper quarter of the C. zhangi Zone. In the Germanic Basin, this short palaeomagnetic interval comprises the lower and the basal part of the upper Fulda Formation. On the Russian Platform, the Nedubrovo Formation belongs to this short reversed magnetic interval. In its upper part (corresponding to the top of the lower C. zhangi Zone, see above) there is a fallout of mafic tuffs from the Siberian Trap event that originated about 3000 km away in eruption centres in the Siberian Tungusska Basin. In the Germanic Basin and in Iran, this horizon contains volcanic microsphaerules. Thus, a direct correlation can be made between the immigration of a cool water fauna into the tropical realm and an exceptionally strong interval of explosive activity during the Siberian Trap volcanic episode. These faunal changes are the same as those found at the base of the Boundary Clay, suggesting that a short cooling event at this horizon also was due to intense volcanism. Additional influence by a bolide impact cannot be excluded. Most of the events in the interval from the C. nodosa up to the I. isarcica Zone (upper Changhsingian to middle Gangetian) in the Iranian sections can be also observed in other marine sections (e.g., in Meishan) and even in continental sections of the Germanic Basin. Of particular significance is the fact that, in the investigated Iranian sections, the PTB lies either in red sediments or in light grey sediments (as in Abadeh) that contain an ostracod fauna indicative of highly oxygenated bottom waters. Therefore, anoxia cannot be the reason for the PTB extinction event in this region, even though anoxia does cause locally or regionally elsewhere an overprint on the extinction event.

Lithostratigraphy, biostratigraphy and chemostratigraphy of Upper Cretaceous and Paleogene sediments from southern Tanzania: Tanzania Drilling Project Sites 27-35

NASA Astrophysics Data System (ADS)

Jimènez Berrocoso, Àlvaro; Huber, Brian T.; MacLeod, Kenneth G.; Petrizzo, Maria Rose; Lees, Jacqueline A.; Wendler, Ines; Coxall, Helen; Mweneinda, Amina K.; Falzoni, Francesca; Birch, Heather; Singano, Joyce M.; Haynes, Shannon; Cotton, Laura; Wendler, Jens; Bown, Paul R.; Robinson, Stuart A.; Gould, Jeremy

2012-07-01

The 2008 Tanzania Drilling Project (TDP) expedition recovered common planktonic foraminifera (PF), calcareous nannofossils (CN) and calcareous dinoflagellates with extraordinary shell preservation at multiple Cenomanian-Campanian sites that will be used for paleoclimatic, paleoceanographic, and biostratigraphic studies. New cores confirm the existence of a more expanded and continuous Upper Cretaceous sequence than had previously been documented in the Lindi and Kilwa regions of southeastern coastal Tanzania. This TDP expedition cored 684.02 m at eight Upper Cretaceous sites (TDP Sites 28-35) and a thin Paleocene section (TDP Site 27). TDP Sites 29, 30, 31 and 34 together span the lowermost Turonian to Coniacian (PF Whiteinella archaeocretacea to Dicarinella concavata Zones and CN Zones UC6a-9b), with TDP Site 31 being the most biostratigraphically complete Turonian section found during TDP drilling. A discontinuous section from the Santonian-upper Campanian (PF D. asymetrica to Radotruncana calcarata Zones and CN Zones UC12-16) was collectively recovered at TDP Sites 28, 32 and 35, while thin sequences of the lower Cenomanian (PF Thalmanninella globotruncanoides Zone and CN subzones UC3a-b) and middle Paleocene (Selandian; PF Zone P3a and CN Zone NP5) were cored in TDP Sites 33 and 27, respectively. Records of δ13Corg and δ13Ccarb from bulk sediments generated for all the Cretaceous sites show largely stable values through the sections. Only a few parallel δ13Corg and δ13Ccarb shifts have been found and they are interpreted to reflect local processes. The δ18Ocarb record, however, is consistent with Late Cretaceous cooling trends from the Turonian into the Campanian. Lithologies of these sites include thick intervals of claystones and siltstones with locally abundant, finely-laminated fabrics, irregular occurrences of thin sandstone layers, and sporadic bioclastic debris (e.g., inoceramids, ammonites). Minor lithologies represent much thinner units of up to medium-grained, massive sandstones. The %CaCO3 (∼5-40%) and %Corg (∼0.1-2%) are variable, with the highest %CaCO3 in the lower Campanian and the highest %Corg in the Turonian. Lithofacies analysis suggests that deposition of these sediments occurred in outer shelf-upper slope, a setting that agrees well with inferences from benthic foraminifera and calcareous dinoflagellates.

Geophysical characteristics of the hydrothermal systems of Kilauea volcano, Hawaii

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

Kauahikaua, J.

1993-08-01

Clues to the structure of Kilauea volcano can be obtained from spatial studies of gravity, magnetic, and seismic velocity variations. The rift zones and summit are underlain by dense, magnetic, and seismic velocity variations. The rift zones and summit are underlain by dense, magnetic, high P-wave-velocity rocks at depths of about 2 km less. The gravity and seismic velocity studies indicate that the rift structures are broad, extending farther to the north than to the south of the surface features. The magnetic data allow separation into a narrow, highly-magnetized, shallow zone and broad, flanking, magnetic lows. The patterns of gravity,more » magnetic variations, and seismicity document the southward migration of the upper east rift zone. Regional, hydrologic features of Kilauea can be determined from resistivity and self-potential studies. High-level groundwater exists beneath Kilauea summit to elevations of +800 m within a triangular area bounded by the west edge of the upper southwest rift zone, the east edge of the upper east rift zone, and the Koa'e fault system. High-level groundwater is present within the east rift zone beyond the triangular summit area. Self-potential mapping shows that areas of local heat produce local fluid circulation in the unconfined aquifer (water table). Shallow seismicity and surface deformation indicate that magma is intruding and that fractures are forming beneath the rift zones and summit area. Heat flows of 370--820 mW/m[sup 2] are calculated from deep wells within the lower east rift zone. The estimated heat input rate for Kilauea of 9 gigawatts (GW) is at least 25 times higher than the conductive heat loss as estimated from the heat flow in wells extrapolated over the area of the summit caldera and rift zones. 115 refs., 13 figs., 1 tab.« less

An integrated geophysical and geochemical exploration of critical zone weathering on opposing montane hillslope

NASA Astrophysics Data System (ADS)

Singha, K.; Navarre-Sitchler, A.; Bandler, A.; Pommer, R. E.; Novitsky, C. G.; Holbrook, S.; Moore, J.

2017-12-01

Quantifying coupled geochemical and hydrological properties and processes that operate in the critical zone is key to predicting rock weathering and subsequent transmission and storage of water in the shallow subsurface. Geophysical data have the potential to elucidate geochemical and hydrologic processes across landscapes over large spatial scales that are difficult to achieve with point measurements alone. Here, we explore the connections between weathering and fracturing, as measured from integrated geochemical and geophysical borehole data and seismic velocities on north- and south-facing aspects within one watershed in the Boulder Creek Critical Zone Observatory. We drilled eight boreholes up to 13 m deep on north- and south-facing aspects within Upper Gordon Gulch, and surface seismic refraction data were collected near these wells to explore depths of regolith and bedrock, as well as anisotropic characteristics of the subsurface material due to fracturing. Optical televiewer data were collected in these wells to infer the dominant direction of fracturing and fracture density in the near surface to corroborate with the seismic data. Geochemical samples were collected from four of these wells and a series of shallow soil pits for bulk chemistry, clay fraction, and exchangeable cation concentrations to identify depths of chemically altered saprolite. Seismic data show that depth to unweathered bedrock, as defined by p-wave seismic velocity, is slightly thicker on the north-facing slopes. Geochemical data suggest that the depth to the base of saprolite ranges from 3-5 m, consistent with a p-wave velocity value of 1200 m/s. Based on magnitude and anisotropy of p-wave velocities together with optical televiewer data, regolith on north-facing slopes is thought to be more fractured than south-facing slopes, while geochemical data indicate that position on the landscape is another important characteristic in determining depths of weathering. We explore the importance of fracture opening in controlling both saprolite and regolith thickness within this watershed.

Melorheostosis involving the cervical and upper thoracic spine: radiographic, CT, and MR imaging findings.

PubMed

Motimaya, A M; Meyers, S P

2006-01-01

Melorheostosis, an uncommon mesenchymal dysplasia, rarely affects the axial skeleton. We describe the imaging findings of melorheostosis involving the cervical and upper thoracic spine. Radiographs and CT showed unilateral well-marginated undulating zones of cortical hyperostosis involving multiple vertebrae that were contiguous with a coalescent ossified right paravertebral mass. MR imaging showed zones of signal intensity void on all pulse sequences without contrast enhancement. Conservative management was elected because of lack of interval clinical and imaging changes for 8 years.

The benthic macrofauna from the Lower Maastrichtian chalk of Kronsmoor (northern Germany, Saturn quarry): taxonomic outline and palaeoecologic implications

NASA Astrophysics Data System (ADS)

Engelke, Julia; Esser, Klaus J. K.; Linnert, Christian; Mutterlose, Jörg; Wilmsen, Markus

2016-12-01

The benthic macroinvertebrates of the Lower Maastrichtian chalk of Saturn quarry at Kronsmoor (northern Germany) have been studied taxonomically based on more than 1,000 specimens. Two successive benthic macrofossil assemblages were recognised: the lower interval in the upper part of the Kronsmoor Formation (Belemnella obtusa Zone) is characterized by low abundances of macroinvertebrates while the upper interval in the uppermost Kronsmoor and lowermost Hemmoor formations (lower to middle Belemnella sumensis Zone) shows a high macroinvertebrate abundance (eight times more than in the B. obtusa Zone) and a conspicuous dominance of brachiopods. The palaeoecological analysis of these two assemblages indicates the presence of eight different guilds, of which epifaunal suspension feeders (fixo-sessile and libero-sessile guilds), comprising approximately half of the trophic nucleus of the lower interval, increased to a dominant 86% in the upper interval, including a considerable proportion of rhynchonelliform brachiopods. It is tempting to relate this shift from the lower to the upper interval to an increase in nutrient supply and/or a shallowing of the depositional environment but further data including geochemical proxies are needed to fully understand the macrofossil distribution patterns in the Lower Maastrichtian of Kronsmoor.

Reconciling laboratory and observational models of mantle rheology in geodynamic modelling

NASA Astrophysics Data System (ADS)

King, Scott D.

2016-10-01

Experimental and geophysical observations constraining mantle rheology are reviewed with an emphasis on their impact on mantle geodynamic modelling. For olivine, the most studied and best-constrained mantle mineral, the tradeoffs associated with the uncertainties in the activation energy, activation volume, grain-size and water content allow the construction of upper mantle rheology models ranging from nearly uniform with depth to linearly increasing from the base of the lithosphere to the top of the transition zone. Radial rheology models derived from geophysical observations allow for either a weak upper mantle or a weak transition zone. Experimental constraints show that wadsleyite and ringwoodite are stronger than olivine at the top of the transition zone; however the uncertainty in the concentration of water in the transition zone precludes ruling out a weak transition zone. Both observational and experimental constraints allow for strong or weak slabs and the most promising constraints on slab rheology may come from comparing inferred slab geometry from seismic tomography with systematic studies of slab morphology from dynamic models. Experimental constraints on perovskite and ferropericlase strength are consistent with general feature of rheology models derived from geophysical observations and suggest that the increase in viscosity through the top of the upper mantle could be due to the increase in the strength of ferropericlase from 20-65 GPa. The decrease in viscosity in the bottom half of the lower mantle could be the result of approaching the melting temperature of perovskite. Both lines of research are consistent with a high-viscosity lithosphere, a low viscosity either in the upper mantle or transition zone, and high viscosity in the lower mantle, increasing through the upper half of the lower mantle and decreasing in the bottom half of the lower mantle, with a low viscosity above the core. Significant regions of the mantle, including high-stress regions of the lower mantle, may be in the dislocation creep (power-law) regime. Due to our limited knowledge of mantle grain size, the best hope to resolve the question of whether a region is in diffusion creep (Newtonian rheology) or dislocation or grain-boundary creep (power-law rheology), may be the presence of absence of seismic anisotropy, because there is no mechanism to rotate crystals in diffusion creep which would be necessary to develop anisotropy from lattice preferred orientation. While non-intuitive, the presence or absence of a weak region in the upper mantle has a profound effect on lower mantle flow. With an asthenosphere, the lower mantle organizes into a long-wavelength plan form with one or two (degree 1 or degree 2) large downwellings and updrafts, which may contain a cluster of plumes. The boundary between the long-wavelength lower mantle flow and upper region flow may be deeper, likely 800-1200 km, than the usually assumed base of the transition zone. There are competing hypotheses as to whether this change in flow pattern is caused by a change in rheology, composition, or phase.

Need to Identify Parameters of Concrete in the Weakest Zone of the Industrial Floor

NASA Astrophysics Data System (ADS)

Stawiski, Bohdan; Radzik, Łukasz

2017-10-01

The ways in which industrial floors are exploited leads to the requirement for the highest strength of their upper zone. Physical phenomena occurring during the compaction and hardening of the concrete cause different strength distributions. In the top zone of industrial floors, the strength is significantly lower (over a dozen MPa) than the strength in the bottom zone (several dozen MPa). Standard tests of control samples do not detect this fact. Processes for the application and finishing of embedded mineral-aggregate hardeners (dry shakes) can be regarded as uncontrolled. The effects of the use of dry shakes are not evaluated. In combination with the phenomenon of bleeding, they often fail by delamination. This paper presents the results of industrial floor testing. The ultrasonic pulse velocity method with dry point contact transducers was used. The results show how upper layer strength was reduced, and how dry shakes application affected the strength of the floor. The strength distribution in hardened concrete, which delaminated from the rest of the floor was presented as well. The extension of compulsory control tests of concrete samples was proposed. In the authors’ opinion, particular attention should be paid to 3 centimetres of the upper layer.

Late Devonian conodonts and event stratigraphy in northwestern Algerian Sahara

NASA Astrophysics Data System (ADS)

Mahboubi, Abdessamed; Gatovsky, Yury

2015-01-01

Conodonts recovered from the Late Devonian South Marhouma section comprise 5 genera with 31 species (3 undetermined). The fauna establishes the presence of MN Zones 5, undifferentiated 6/7, 8/10 for the Middle Frasnian, the MN Zones 11, 12, 13 for the Upper Frasnian as well as the Early through Late triangularis Zones in the basal Famennian. The outcropping lithological succession is one of mostly nodular calcilutites alternating with numerous marly and shaly deposits, which, in the lower and upper part, comprise several dysoxic dark shale intervals. Among these the Upper Kellwasser horizon can be precisely dated and as such the presence of the terminal Frasnian Kellwasser Event is recognized for the first time in Algeria. Both the Middlesex and Rhinestreet Events cannot yet be precisely located, but supposedly occur among the dark shale horizons in the lower part of the section. However, their assignment to a precise level has so far not been established. Though poor in conodont abundance the South Marhouma section provides first evidence of the presence of several Montagne Noire conodont zones within the so far widely unstudied Frasnian of the Ougarta Chain. As such it is considered representative for the northwestern Algerian Saoura region.

Saltwater intrusion in the Floridan aquifer system near downtown Brunswick, Georgia, 1957–2015

USGS Publications Warehouse

Cherry, Gregory S.; Peck, Michael

2017-02-16

IntroductionThe Floridan aquifer system (FAS) consists of the Upper Floridan aquifer (UFA), an intervening confining unit of highly variable properties, and the Lower Floridan aquifer (LFA). The UFA and LFA are primarily composed of Paleocene- to Oligocene-age carbonate rocks that include, locally, Upper Cretaceous rocks. The FAS extends from coastal areas in southeastern South Carolina and continues southward and westward across the coastal plain of Georgia and Alabama, and underlies all of Florida. The thickness of the FAS varies from less than 100 feet (ft) in aquifer outcrop areas of South Carolina to about 1,700 ft near the city of Brunswick, Georgia.Locally, in southeastern Georgia and the Brunswick– Glynn County area, the UFA consists of an upper water-bearing zone (UWBZ) and a lower water-bearing zone (LWBZ), as identified by Wait and Gregg (1973), with aquifer test data indicating the upper zone has higher productivity than the lower zone. Near the city of Brunswick, the LFA is composed of two permeable zones: an early middle Eocene-age upper permeable zone (UPZ) and a highly permeable lower zone of limestone (LPZ) of Paleocene and Late Cretaceous age that includes a deeply buried, cavernous, saline water-bearing unit known as the Fernandina permeable zone. Maslia and Prowell (1990) inferred the presence of major northeast–southwest trending faults through the downtown Brunswick area based on structural analysis of geophysical data, northeastward elongation of the potentiometric surface of the UFA, and breaches in the local confining unit that influence the area of chloride contamination. Pronounced horizontal and vertical hydraulic head gradients, caused by pumping in the UFA, allow saline water from the FPZ to migrate upward into the UFA through this system of faults and conduits.Saltwater was first detected in the FAS in wells completed in the UFA near the southern part of the city of Brunswick in late 1957. By the 1970s, a plume of groundwater with high chloride concentrations had migrated northward toward two major industrial pumping centers, and since 1965, chloride concentrations have steadily increased in the northern part of the city. In 1978, data obtained from a 2,720-ft-deep test well (33H188) drilled south of the city showed water with a chloride concentration of 33,000 milligrams per liter (mg/L), suggesting the saltwater source was located below the UFA in the Fernandina permeable zone (FPZ) of the LFA.All U.S. Geological Survey (USGS) data collected for this study, including groundwater levels in wells and water-chemistry data, are available in the USGS National Water Information System.

Upper-Mantel Earthquakes in the Australia-Pacific Plate Boundary Zone and the Roots of the Alpine Fault

NASA Astrophysics Data System (ADS)

Boese, C. M.; Warren-Smith, E.; Townend, J.; Stern, T. A.; Lamb, S. H.

2016-12-01

Seismicity in the upper mantle in continental collision zones is relatively rare, but observed around the world. Temporary seismometer deployments have repeatedly detected mantle earthquakes at depths of 40-100 km within the Australia-Pacific plate boundary zone beneath the South Island of New Zealand. Here, the transpressive Alpine Fault constitutes the primary plate boundary structure linking subduction zones of opposite polarity farther north and south. The Southern Alps Microearthquake Borehole Array (SAMBA) has been operating continuously since November 2008 along a 50 km-long section of the central Alpine Fault, where the rate of uplift of the Southern Alps is highest. To date it has detected more than 40 small to moderate-sized mantle events (1≤ML≤3.9). The Central Otago Seismic Array (COSA) has been in operation since late 2012 and detected 15 upper mantle events along the sub-vertical southern Alpine Fault. Various mechanisms have been proposed to explain the occurrence of upper mantle seismicity in the South Island, including intra-continental subduction (Reyners 1987, Geology); high shear-strain gradients due to depressed geotherms and viscous deformation of mantle lithosphere (Kohler and Eberhart-Phillips 2003, BSSA); high strain rates resulting from plate bending (Boese et al. 2013, EPSL), and underthrusting of the Australian plate (Lamb et al. 2015, G3). Focal mechanism analysis reveals a variety of mechanisms for the upper mantle events but predominantly strike-slip and reverse faulting. In this study, we apply spectral analysis to better constrain source parameters for these mantle events. These results are interpreted in conjunction with new information about crustal structure and low-frequency earthquakes near the Moho and in light of existing velocity, attenuation and resistivity models.

Structural evolution of the Sarandí del Yí Shear Zone, Uruguay: kinematics, deformation conditions and tectonic significance

NASA Astrophysics Data System (ADS)

Oriolo, S.; Oyhantçabal, P.; Heidelbach, F.; Wemmer, K.; Siegesmund, S.

2015-10-01

The Sarandí del Yí Shear Zone is a crustal-scale shear zone that separates the Piedra Alta Terrane from the Nico Pérez Terrane and the Dom Feliciano Belt in southern Uruguay. It represents the eastern margin of the Río de la Plata Craton and, consequently, one of the main structural features of the Precambrian basement of Western Gondwana. This shear zone first underwent dextral shearing under upper to middle amphibolite facies conditions, giving rise to the reactivation of pre-existing crustal fabrics in the easternmost Piedra Alta Terrane. Afterwards, pure-shear-dominated sinistral shearing with contemporaneous magmatism took place under lower amphibolite to upper greenschist facies conditions. The mylonites resulting from this event were then locally reactivated by a cataclastic deformation. This evolution points to strain localization under progressively retrograde conditions with time, indicating that the Sarandí del Yí Shear Zone represents an example of a thinning shear zone related to the collisional to post-collisional evolution of the Dom Feliciano Belt that occurred between the Meso- to Neoproterozoic (>600 Ma) and late Ediacaran-lower Cambrian times.

Trench curvature initiation: Upper plate strain pattern and volcanism Insights from the Lesser Antilles arc, St Barthélemy Island, FWI.

NASA Astrophysics Data System (ADS)

Philippon, M. M.; Legendre, L.; Münch, P.; Léticée, J. L.; Lebrun, J. F.; Maincent, G.; Mazabraud, Y.

2017-12-01

Upper plate deformation pattern reflect the mechanical behavior of subduction zones. In this study, we focus on the consequence of the entrance of a buoyant plateau within the Caribbean subduction zone during Eocene by studying the oldest cropping out rocks of the Lesser Antilles volcanic arc. Based on novel geochronological ages and available bio-stratigraphic data we show that St Barthélemy Island was built during three successive volcanic events over the Mid- Eocene to Oligo-Miocene time span. We show that magmatism is mainly Oligocene, not Eocene. Moreover, we demonstrate that tholeitic and calc-alkaline magmatism co-existed all along the arc activity. And ultimately we evidence a westward migration of the volcanism at the island scale. Furthermore, We demonstrate that during 21 Ma, the built of theses volcanoes, the stress regime evolves from pure to radial extension with a sub-horizontal σ3 showing N30° mean trend. To conclude, our novel results invalidate the chronological, geochemical and spatial evolution of the island arc magmatism formerly proposed in the early eighties. Indeed, arc magmatism in St Barthélemy was mainly related to the West-dipping Lesser Antilles subduction zone and not to the South-dipping Greater Antilles subduction and upper plate deformation evolution observed at local scale reflects large scale mechanical behavior of the Lesser Antilles subduction zone. A two steps restoration of the regional deformation shows that the switch from pure parallel to the trench extension to radial extension within the Caribbean upper plate reflects trench curvature that followed the entrance of the Bahamas bank in the Greater Antilles subduction zone and its collision.

TOMOGRAPHY OF PLASMA FLOWS IN THE UPPER SOLAR CONVECTION ZONE USING TIME-DISTANCE INVERSION COMBINING RIDGE AND PHASE-SPEED FILTERING

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

Svanda, Michal, E-mail: michal@astronomie.cz; Astronomical Institute, Charles University in Prague, Faculty of Mathematics and Physics, V Holesovickach 2, CZ-18000 Prague 8

2013-09-20

The consistency of time-distance inversions for horizontal components of the plasma flow on supergranular scales in the upper solar convection zone is checked by comparing the results derived using two k-{omega} filtering procedures-ridge filtering and phase-speed filtering-commonly used in time-distance helioseismology. I show that both approaches result in similar flow estimates when finite-frequency sensitivity kernels are used. I further demonstrate that the performance of the inversion improves (in terms of a simultaneously better averaging kernel and a lower noise level) when the two approaches are combined together in one inversion. Using the combined inversion, I invert for horizontal flows inmore » the upper 10 Mm of the solar convection zone. The flows connected with supergranulation seem to be coherent only for the top {approx}5 Mm; deeper down there is a hint of change of the convection scales toward structures larger than supergranules.« less

Sediment Flux of Particulate Organic Phosphorus in the Open Black Sea

NASA Astrophysics Data System (ADS)

Parkhomenko, A. V.; Kukushkin, A. S.

2018-03-01

The interannual variation of the monthly average (weighted average) concentrations of particulate organic phosphorus (PPOM) in the photosynthetic layer, oxycline, redox zone, and H2S zone in the open Black Sea is estimated based on long-term observation data. The suspension sedimentation rates from the studied layers are assessed using model calculations and published data. The annual variation of PPOM sediment fluxes from the photosynthetic layer, oxycline, redox zone, and upper H2S zone to the anaerobic zone of the sea and the correspondingly annual average values are estimated for the first time. A regular decrease in the PPOM annual average flux with depth in the upper active layer is demonstrated. A correlation between the annual average values of PPOM sediment flux from the photosynthetic layer and ascending phosphate flux to this layer is shown, which suggests their balance in the open sea. The results are discussed in terms of the phosphorus biogeochemical cycle and the concept of new and regenerative primary production in the open Black Sea.

Where should the upper boundary of the earth's critical zone be?

NASA Astrophysics Data System (ADS)

Liu, W.; Zhang, X. J.

2017-12-01

Recently increasing attention has been paid to the study of the critical zone (CZ) of the earth. The upper boundary of the CZ is generally defined as the top of plant canopy, and the lower boundary at the bottom of deep groundwater. The question is whether the ecological, biogeochemical and hydrological processes that are the focuses of CZ research occur within the scope of such boundaries. The role of water is central in these processes as is shown by the current studies as follows. First, there exist water vapor transport strips or pathways with higher flux strength than the surrounding areas in the troposphere, known as "tropospheric rivers" or "atmospheric rivers" (Newell, et al, 1992; Zhu, et al, 1998), specially dubbed as "sky rivers" (Wang, et al, 2016). The sky rivers are connected with the surface and underground rivers by precipitation and evapotranspiration processes, forming a complete water cycle system of the earth. Second, changes in atmospheric composition, such as aerosol increases, the formation of smog, CO2 concentration rising, directly or indirectly affected solar radiation and plant growth, which to a large extent determine potential evapotranspiration and vegetation cover change. Based on the Budyko model, annual water balance at a catchment is closely related to these changes (Zhang, et al., 2001; Ning, et al., 2017). Third, the theory of evaporation complementarity holds that surface evapotranspiration can be completely determined and calculated by meteorological data. Based on the eddy covariance observation for water and heat flux in the Loess Plateau (Brutsaert, et al., 2017), the relationship between calculated and observed ET values becomes stronger from 2m to 32m, which may be related to the existence of a blending height at higher elevations above the ground. Therefore, we deem that the CZ upper boundary should be selected at the tropopause of the atmosphere. The troposphere, directly affected by the earth surface, contains 3/4 of total mass of the whole atmosphere and almost all water vapor. Such a specification of the vertical CZ will afford comprehensive, systematic and in-depth studies on the near surface layer with focus on water role and cycle. This would also help define and attack the world problems regarding resources, environment and ecological services.

Interaction of the Cyprus/Tethys Slab With the Mantle Transition Zone Beneath Anatolia

NASA Astrophysics Data System (ADS)

Thompson, D. A.; Rost, S.; Taylor, G.; Cornwell, D. G.

2017-12-01

The geodynamics of the eastern Mediterranean are dominated by northward motion of the Arabian/African continents and subduction of the oldest oceanic crust on the planet along the Aegean and Cyprean trenches. These slabs have previously been imaged using seismic tomography on a continental scale, but detailed information regarding their descent from upper to lower mantle and how they interact with the mantle transition zone have been severely lacking. The Dense Array for North Anatolia (DANA) was a 73 station passive seismic deployment active between 2012-2013 with the primary aim of imaging shallow structure beneath the North Anatolian Fault. However, we exploit the exceptional dataset recorded by DANA to characterise a region where the Cyprus Slab impinges upon the mantle transition zone beneath northern Turkey, providing arguably the most detailed view of a slab as it transits from the upper to lower mantle. We map varying depths and amplitudes of the transition zone seismic discontinuities (`410', `520' and `660') in 3D using over 1500 high quality receiver functions over an area of approximately 200km x 300km. The `410' is observed close to its predicted depth, but the `660' is depressed to >670 km across the entirety of the study region. This is consistent with an accumulation of cold subducted material at the base of the upper mantle, and the presence of a `520' discontinuity in the vicinity of the slab surface also suggests that the slab is present deep within the transition zone. Anomalous low velocity layers above and within the transition zone are constrained and may indicate hydration and ongoing mass/fluid flux between upper and lower mantle in the presence of subduction. The results of the study have implications not only for the regional geodynamics of Anatolia, but also for slab dynamics globally.

Slab geometry of the South American margin from joint inversion of body waves and surface waves

NASA Astrophysics Data System (ADS)

Porritt, R. W.; Ward, K. M.; Porter, R. C.; Portner, D. E.; Lynner, C.; Beck, S. L.; Zandt, G.

2016-12-01

The western margin of South America is a long subduction zone with a complex, highly three -dimensional geometry. The first order structure of the slab has previously been inferred from seismicity patterns and locations of volcanoes, but confirmation of the slab geometry by seismic imaging for the entire margin has been limited by either shallow, lithospheric scale models or broader, upper mantle images, often defined on a limited spatial footprint. Here, we present new teleseismic tomographic SV seismic models of the upper mantle from 10°S to 40°S along the South American subduction zone with resolution to a depth of 1000 km as inferred from checkerboard tests. In regions near the Peru Bolivia border (12°S to 18°S) and near central Chile and western Argentina (29.5°S to 33°S) we jointly invert the multi-band direct S and SKS relative delay times with Rayleigh wave phase velocities from ambient noise and teleseismic surface wave tomography. This self-consistent model provides information from the upper crust to below the mantle transition zone along the western margin in these two regions. This consistency allows tracing the slab from the South American coastline to the sub-transition zone upper mantle. From this model we image several features, but most notable is a significant eastward step near the southern edge of the margin (24°-30° S). West of this step, a large high shear velocity body is imaged in the base of and below the transition zone. We suggest this may be a stagnant slab, which is descending into the lower mantle now that it is no longer attached to the surface. This suggests a new component to the subduction history of western South America when an older slab lead the convergence before anchoring in the transition zone, breaking off from the surface, and being overtaken by the modern, actively subducting slab now located further east.

Zone heating for fluidized bed silane pyrolysis

NASA Technical Reports Server (NTRS)

Iya, Sridhar K. (Inventor)

1987-01-01

An improved heated fluidized bed reactor and method for the production of high purity polycrystalline silicon by silane pyrolysis wherein silicon seed particles are heated in an upper heating zone of the reactor and admixed with particles in a lower reaction zone, in which zone a silane-containing gas stream, having passed through a lower cooled gas distribution zone not conducive to silane pyrolysis, contacts the heated seed particles whereon the silane is heterogeneously reduced to silicon.

Mapping the influence of the deep Nazca slab on the geometry of the 660-km discontinuity beneath stable South America

NASA Astrophysics Data System (ADS)

Bianchi, M. B. D.; Assumpcao, M.; Julià, J.

2017-12-01

The fate of the deep Nazca subducted plate is poorly mapped under stable South America. Transition zone thickness and position is greatly dependent on mantle temperature and so is influenced by the colder Nazca plate position. We use a database of 35,000 LQT deconvolved receiver function traces to image the mantle transition zone and other upper mantle discontinuities under different terranes of stable South American continent. Data from the entire Brazilian Seismographic Network database, consisting of more than 80 broadband stations supplemented by 35 temporary stations deployed in west Brazil, Argentina, Paraguay, Bolivia and Uruguay were processed. Our results indicates that upper mantle velocities are faster than average under stable cratons and that most of the discontinuities are positioned with small variations in respect to nominal depths, except in places were the Nazca plate interacts with the transition zone. Under the Chaco-Pantanal basin the Nazca plate appears to be trapped in the transition zone for more than 1000 km with variations of up to 30 km in 660 km discontinuity topography under this region consistent with global tomographic models. Additional results obtained from SS precursor analysis of South Sandwich Islands teleseismic events recorded at USArray stations indicates that variations of transition zones thickness occur where the Nazca plate interacts with the upper mantle discontinuities in the northern part of Stable South American continent.

Mantle transition zone structure beneath the Canadian Shield

NASA Astrophysics Data System (ADS)

Thompson, D. A.; Helffrich, G. R.; Bastow, I. D.; Kendall, J. M.; Wookey, J.; Eaton, D. W.; Snyder, D. B.

2010-12-01

The Canadian Shield is underlain by one of the deepest and most laterally extensive continental roots on the planet. Seismological constraints on the mantle structure beneath the region are presently lacking due to the paucity of stations in this remote area. Presented here is a receiver function study on transition zone structure using data from recently deployed seismic networks from the Hudson Bay region. High resolution images based on high signal-to-noise ratio data show clear arrivals from the 410 km and 660 km discontinuities, revealing remarkably little variation in transition zone structure. Transition zone thickness is close to the global average (averaging 245 km across the study area), and any deviations in Pds arrival time from reference Earth models can be readily explained by upper-mantle velocity structure. The 520 km discontinuity is not a ubiquitous feature, and is only weakly observed in localised areas. These results imply that the Laurentian root is likely confined to the upper-mantle and if any mantle downwelling exists, possibly explaining the existence of Hudson Bay, it is also confined to the upper 400 km. Any thermal perturbations at transition zone depths associated with the existence of the root, whether they be cold downwellings or elevated temperatures due to the insulating effect of the root, are thus either non-existent or below the resolution of the study.

Agricultural Intensification in the Amazon: Tracking Nitrogen Fertilizer from Soy-Maize Double Cropping to Streams

NASA Astrophysics Data System (ADS)

Cabrera, V. D.; Jankowski, K.; Neill, C.; Macedo, M.; Deegan, L.; Brando, P. M.; Nascimento, S.; Nascimento, E.; Rocha, S.; Coe, M. T.; Nunes, D.

2015-12-01

Globalization and the increasing demand for food create pressure to both expand and intensify agriculture. These changes have potentially large consequences for the solute concentrations and functioning of streams. In the Brazilian Amazon, crop agriculture expanded greatly during the last 20 years. More recently, farmers have intensified production on existing cropland by double cropping of soy and maize during the same year. Maize, a novel crop for the region, requires much higher applications of nitrogen (N) fertilizer than soybeans. To determine whether this novel land use and associated N addition influenced N concentrations in groundwater and stream water, we measured N concentrations in groundwater wells and streams from small headwater watersheds across three land uses (soy-maize, soy, and tropical forest) in the Upper Xingu Basin, a region of rapid cropland intensification in the southern Amazon. Each watershed contained six groundwater wells arranged in a transect reaching cropland field edge on either side of the stream. Total inorganic N concentrations were higher in wells adjacent to fields where double cropping occurred, while stream concentrations did not differ overall among land uses. This suggests the riparian zones are critical in the removal of N, but as the intensification of agriculture continues the ability of the riparian zone to prevent N from traveling to streams is unknown. Their protection is critical to the functioning of tropical watersheds.

Making the most of CZ seismics: Improving shallow critical zone characterization using surface-wave analysis

NASA Astrophysics Data System (ADS)

Pasquet, S.; Wang, W.; Holbrook, W. S.; Bodet, L.; Carr, B.; Flinchum, B. A.

2017-12-01

Estimating porosity and saturation in the shallow subsurface over large lateral scales is vitally important for understanding the development and evolution of the Critical Zone (CZ). Because elastic properties (P- and S-wave velocities) are particularly sensitive to porosity and saturation, seismic methods (in combination with petrophysical models) are effective tools for mapping CZ architecture and processes. While many studies employ P-wave refraction methods, fewer use the surface waves that are typically also recorded in those same surveys. Here we show the value of exploiting surface waves to extract supplementary shear-wave velocity (Vs) information in the CZ. We use a new, user-friendly, open-source MATLAB-based package (SWIP) to invert surface-wave data and estimate lateral variations of Vs in the CZ. Results from synthetics show that this approach enables the resolution of physical property variations in the upper 10-15 m below the surface with lateral scales of about 5 m - a vast improvement compared to P-wave tomography alone. A field example at a Yellowstone hydrothermal system also demonstrates the benefits of including Vs in the petrophysical models to estimate not only porosity but also saturation, thus highlighting subsurface gas pathways. In light of these results, we strongly suggest that surface-wave analysis should become a standard approach in CZ seismic surveys.

Crustal structure between Lake Mead, Nevada, and Mono Lake, California

USGS Publications Warehouse

Johnson, Lane R.

1964-01-01

Interpretation of a reversed seismic-refraction profile between Lake Mead, Nevada, and Mono Lake, California, indicates velocities of 6.15 km/sec for the upper layer of the crust, 7.10 km/sec for an intermediate layer, and 7.80 km/sec for the uppermost mantle. Phases interpreted to be reflections from the top of the intermediate layer and the Mohorovicic discontinuity were used with the refraction data to calculate depths. The depth to the Moho increases from about 30 km near Lake Mead to about 40 km near Mono Lake. Variations in arrival times provide evidence for fairly sharp flexures in the Moho. Offsets in the Moho of 4 km at one point and 2 1/2 km at another correspond to large faults at the surface, and it is suggested that fracture zones in the upper crust may displace the Moho and extend into the upper mantle. The phase P appears to be an extension of the reflection from the top of the intermediate layer beyond the critical angle. Bouguer gravity, computed for the seismic model of the crust, is in good agreement with the measured Bouguer gravity. Thus a model of the crustal structure is presented which is consistent with three semi-independent sources of geophysical data: seismic-refraction, seismic-reflection, and gravity.

Physical stratigraphy, paleontology, and magnetostratigraphy of the USGS-Santee Coastal Reserve core (CHN-803), Charleston County, South Carolina

USGS Publications Warehouse

Edwards, Lucy E.; Gohn, G.S.; ,; Prowell, D.C.; Bybell, L.M.; Bardot, L.P.; Firth, J.V.; Huber, B.T.; Frederiksen, N.O.; MacLeod, K.G.

1999-01-01

The Santee Coastal Reserve core, a 545-ft-deep corehole in northeastern Charleston County, South Carolina, recovered sediments of Late Cretaceous, Paleocene, Eocene, and Quaternary age. The deepest sediments, the Donoho Creek Formation (545-475.7 ft), consist of 69.3 ft of muddy calcareous sand of marine origin. This formation is placed within the upper Campanian calcareous nannofossil Subzone CC 22c. The overlying Peedee Formation (475.7-367.1 ft) in the core consists of 108.6 ft of silty clay of marine origin. It is placed in upper Maastrichtian calcareous nannofossil Subzones CC 25b, CC 26a, and CC 26b. Combined fossil and paleomagnetic information indicates nearly continuous deposition. Foraminifers indicate an outer neritic paleobathymetric setting. The Rhems Formation sensu stricto (367.1-267.3 ft) consists of 99.8 ft of silty clay, muddy sand, and minor calcite-cemented, shelly sand of marine origin. It is apparently the product of rapid sediment accumulation during a short period of time in the early Paleocene (calcareous nannofossil Zone NP 1). The upper part of the Rhems Formation sensu Bybell and others (1998) (267.3-237.4 ft) consists of 29.9 ft of calcite-cemented muddy sand and burrowed fine sand of marine origin. It is placed in calcareous nannofossil Zone NP 4 and, because it shows normal polarity, likely represents the upper part of the lower Paleocene. This unit may be correlative with the lower part of the Lower Bridge Member of the Williamsburg Formation in its type area. The Lower Bridge Member of the Williamsburg Formation (237.4-125.0 ft) has an unconformable contact at 205.0 ft that divides the member into lower muddy sand beds and upper calcareous clay beds. Both are placed in the upper Paleocene calcareous nannofossil Zone NP 5. The Chicora Member of the Williamsburg Formation (125-51.5 ft) consists of 73.5 ft of muddy, shelly sand of marine origin. It is poorly dated but includes late Paleocene nannofossils (Zones NP 5 and NP 6). A mollusk-bryozoan limestone (51.5-42.0 ft) above the Chicora Member of the Williamsburg yields early Eocene calcareous nannofossils representing both Zone NP 9/10 and Zone NP 12, together with pollen and dinocysts that are younger. Sediments of middle and late Eocene, Oligocene, Miocene, and Pliocene ages were not recovered in the Santee Coastal Reserve core. The upper 42.0 ft of sediments represent Quaternary deposits and are included in the Wando Formation (42.0-28.0 ft) and the informal Silver Bluff beds (28.0-0 ft).

Upper Cretaceous subsurface stratigraphy and structure of coastal Georgia and South Carolina

USGS Publications Warehouse

Valentine, Page C.

1982-01-01

Upper Cretaceous subsurface stratigraphy and structure of coastal Georgia and South Carolina is based on the study of 24 wells along two transects, one extending across the seaward-dipping sedimentary basin termed the 'Southeast Georgia Embayment' northeastward to the crest of the Cape Fear Arch, and the other alined east-west, parallel to the basin axis and including the COST GE-l well on the Outer Continental Shelf. A new biostratigraphic analysis, using calcareous nannofossils, of the Fripp Island, S.C., well and reinterpretations of the Clubhouse Crossroads corehole 1, South Carolina, and other wells in South Carolina, Georgia, and northernmost Florida have made possible the comparison and reevaluation of stratigraphic interpretations of the region made by G. S. Gohn and others in 1978 and 1980 and by P. M. Brown and others in 1979. The present study indicates that within the Upper Cretaceous section the stratigraphic units formerly assigned a Cenomanian (Eaglefordian and Woodbinian) age are Coniacian (Austinian) and Turonian (Eaglefordian) in age. A previously described hiatus encompassing Coniacian and Turonian time is not present. More likely, a hiatus is probably present in the upper Turonian, and major gaps in the record are present within the Cenomanian and between the Upper Cretaceous and the pre-Cretaceous basement. After an erosional episode in Cenomanian time that affected the section beneath eastern Georgia and South Carolina, Upper Cretaceous marine clastic and carbonate rocks were deposited on a regionally subsiding margin that extended to the present Blake Escarpment. In contrast, during Cenozoic time, especially in the Eocene, subsidence and sedimentation rates were uneven across the margin. A thick progradational sequence of carbonate rocks accumulated in the Southeast Georgia Embayment and also built the present Continental Shelf, whereas farther offshore a much thinner layer of sediments was deposited on the Blake Plateau. There is no general agreement on the exact placement of the Cenomanian-Turonian boundary in Europe or the United States Western Interior, and the widespread Sciponoceras gracile ammonite zone represents an interval of equivocal age between accepted Cenomanian and Turonian strata. The extinction of the foraminifer genus Rotalipora took place within the Sciporwceras gracile zone; it is used here to identify the Cenomanian-Turonian boundary. Pollen zone IV (Complexiopollis-Atlantopollis assemblage zone) is an important and widespread biostratigraphic unit characterized by a distinctive spore and pollen flora. It is consistently associated with lower Turonian calcareous nannofossils on the Atlantic continental margin; these nannofossil assemblages are also present in pollen zone IV, in strata that encompass the Sciponoceras gracile zone and the lower part of the Mytiloides labiatus zone in the Gulf Coastal Plain at Dallas, Tex.

Creep cavitation can establish a dynamic granular fluid pump in ductile shear zones.

PubMed

Fusseis, F; Regenauer-Lieb, K; Liu, J; Hough, R M; De Carlo, F

2009-06-18

The feedback between fluid migration and rock deformation in mid-crustal shear zones is acknowledged as being critical for earthquake nucleation, the initiation of subduction zones and the formation of mineral deposits. The importance of this poorly understood feedback is further highlighted by evidence for shear-zone-controlled advective flow of fluids in the ductile lower crust and the recognition that deformation-induced grain-scale porosity is a key to large-scale geodynamics. Fluid migration in the middle crust cannot be explained in terms of classical concepts. The environment is considered too hot for a dynamic fracture-sustained permeability as in the upper crust, and fluid pathways are generally too deformed to be controlled by equilibrium wetting angles that apply to hotter, deeper environments. Here we present evidence that mechanical and chemical potentials control a syndeformational porosity generation in mid-crustal shear zones. High-resolution synchrotron X-ray tomography and scanning electron microscopy observations allow us to formulate a model for fluid migration in shear zones where a permeable porosity is dynamically created by viscous grain-boundary sliding, creep cavitation, dissolution and precipitation. We propose that syndeformational fluid migration in our 'granular fluid pump' model is a self-sustained process controlled by the explicit role of the rate of entropy production of the underlying irreversible mechanical and chemical microprocesses. The model explains fluid transfer through the middle crust, where strain localization in the creep regime is required for plate tectonics, the formation of giant ore deposits, mantle degassing and earthquake nucleation. Our findings provide a key component for the understanding of creep instabilities in the middle crust.

Extensional deformation of the Guadalquivir Basin: rate of WSW-ward tectonic displacement from Upper Tortonian sedimentary rocks

NASA Astrophysics Data System (ADS)

Roldán, Francisco J.; Azañón, Jose Miguel; Rodríguez-Fernández, Jose; María Mateos, Rosa

2016-04-01

The Guadalquivir Basin (Upper Tortonian-Quaternary sedimentary infilling) has been considered the foreland basin of the Betic Orogen built up during its collision with the Sudiberian margin. The basin is currently restricted to its westernmost sector, in the Cadiz Gulf, because the Neogene-Quaternary uplift of the Betic Cordillera has produced the emersion of their central and eastern parts. The upper Tortonian chronostratigraphic unit is the oldest one and it was indistinctly deposited on the South Iberian paleomargin and the External units from the Betic Cordillera. However, these rocks are undeformed on the Sudiberian paleomargin while they are deeply affected by brittle deformation on the External Betic Zone. Outcrops of Upper Tortonian sedimentary rocks on External Betic Zone are severely fragmented showing allocthonous characters with regard to those located on the Sudiberian paleomargin. This post- Upper Tortonian deformation is not well known in the External Zones of the Cordillera where the most prominent feature is the ubiquity of a highly deformed tecto-sedimentary unit outcropping at the basement of the Guadalquivir sedimentary infilling. This tecto-sedimentary unit belongs to the Mass Wasting Extensional Complex (Rodríguez-Fernández, 2014) formed during the collision and westward migration of the Internal Zone of the Betic Cordillera (15-8,5 Ma). In the present work, we show an ensemble of tectonic, geophysical and cartographic data in order to characterize the post-Upper Tortonian deformation. For this, seismic reflection profiles have been interpreted with the help of hidrocarbon boreholes to define the thickness of the Upper Tortonian sedimentary sequence. All these data provide an estimation of the geometrical and kinematic characteristics of the extensional faults, direction of movement and rate of displacement of these rocks during Messinian/Pliocene times. References Rodríguez-Fernández, J., Roldan, F. J., J.M. Azañón y Garcia-Cortes, A. 2013. EL colapso gravitacional del frente orogénico alpino en el Dominio Subbético durante el Mioceno medio-superior: El Complejo Extensional Subbético. Boletín Geológico y Minero, 124 (3): 477-504

Transport and transformation of genetic information in the critical zone: The case of antibiotic resistance genes

NASA Astrophysics Data System (ADS)

Zhu, Y. G.

2015-12-01

In addition to material and energy flows, the dynamics and functions of the Earth's critical zone are intensively mediated by biological actions performed by diverse organisms. These biological actions are modulated by the expression of functional genes and their translation into enzymes that catalyze geochemical reactions, such as nutrient turnover and pollutant biodegradation. Although geobiology, as an interdisciplinary research area, is playing and vital role in linking biological and geochemical processes at different temporal and spatial scales, the distribution and transport of functional genes have rarely been investigated from the Earth's critical zone perspectives. To illustrate the framework of studies on the transport and transformation of genetic information in the critical zone, antibiotic resistance is taken as an example. Antibiotic resistance genes are considered as a group of emerging contaminants, and their emergence and spread within the critical zone on one hand are induced by anthropogenic activities, and on other hand are threatening human health worldwide. The transport and transformation of antibiotic resistance genes are controlled by both horizontal gene transfer between bacterial cells and the movement of bacteria harboring antibiotic resistance genes. In this paper, the fate and behavior of antibiotic resistance genes will be discussed in the following aspects: 1) general overview of environmental antibiotic resistance; 2) high through quantification of the resistome in various environmental media; 3) pathways of resistance gene flow within the critical zone; and 4) potential strategies in mitigating antibiotic resistance, particularly from the critical zone perspectives.

The Mechanism and Dynamics of N-S Rifting in Southern Tibet: Insight From 3-D Thermomechanical Modeling

NASA Astrophysics Data System (ADS)

Pang, Yajin; Zhang, Huai; Gerya, Taras V.; Liao, Jie; Cheng, Huihong; Shi, Yaolin

2018-01-01

N-S trending rifts are widely distributed in southern Tibet, suggesting that this region is under E-W extension, behind the N-S collision between the Eurasia and India plates. Geophysical anomalies and Miocene magma extrusions indicate the presence of dispersed weak zones in the middle to lower crust in southern Tibet. These weak zones are partially located underneath the N-S rifting systems. In order to study the formation of rifts in collision zones, we have developed a high-resolution 3-D thermomechanical model of continental lithosphere with bidirectional compressional-extensional deformation, and spatially localized weak and low-density zones in the middle to lower crust. Our numerical experiments systematically reproduce the development of N-S trending rifts. Model results reveal that the weak middle to lower crust triggers the development of normal faults in the upper crust and surface uplift, whereas regions without such weak layer or with small-scale weak zones are characterized by strike-slip faulting. Geodynamic properties (density, depth, and geometry) of the weak middle to lower crust and Moho temperature notably influence the rifting pattern. In addition, rifting formation is critically controlled by large E-W extension, with the ratio of extensional to compressional strain rate larger than 1.5 in the model with continuous weak middle crust. Our simulated rifting patterns correlate well with the observations in southern Tibet; we conclude that a combination of the bidirectional compression-extension and the presence of locally weak middle to lower crust triggered the development of the rifting systems in southern Tibet.

Structure of the Sumatra wedge affected by the 26th December 2004 :Effects of the lower plate volcanic ridges.

NASA Astrophysics Data System (ADS)

Rangin, C.; Sibuet, J. C.; Lin, J. Y.; Le Pichon, X.

2009-04-01

Detailed swath-bathymetry, coupled with echo-sounder data were collected offshore the northern tip of Sumatra over the rupture area of the 26th December 2004 Mw=9.2 earthquake during the Sumatra aftershock cruise. 20 ocean bottom seismometers were also deployed in the northern Sumatra area., and more than 1000 events were identified during the 12 days recording period. We mapped recently active steeply dipping thrust fault zone within the western termination of the Sunda accreted wedge. Main N10°W trending out of sequence thrust fault zones with a discrete westward vergency and some component of dextral strike-slip motion were continuously mapped within the wedge, on the basis of bathymetry and low frequency sounder profiles. The interplate boundary does not appear to extend into the frontal part of the wedge but most probably merges in its central part along these major faults, the Lower and Upper Splay Faults. After relocation, the seismicity shows different pattern in each side of this Upper Splay Fault. East of this boundary, beneath the Aceh basin, the earthquake depths ranged from 30 to 60 km allow us to illustrate the subducted plate. In the western part, the aftershock distribution is strongly influenced by the N-S orientated oceanic fracture zones. Two clusters of earthquakes between 10 and 50 km in depth trending along N-S direction are observed in the lower wedge that we interpret to be reactive fracture zones. The lower wedge is interpreted as the northern prolongation below the wedge of the lower plate NS oceanic fracture zone ridges affected by NS trending left lateral strike-slip faults. This wedge outer ridge is in the process of being transferred to the upper plate. On the other hand the central ridge is interpreted as possible stacked volcanic ridge slivers already incorporated into the upper plate along the subduction buttress (the inner ridge of the wedge). We propose that the tectonic interaction of the volcanic Indian Ocean fracture ridges of the subducted plate with the leading edge of the upper Sunda plate subduction zone is an active tectonic transfer process of oceanic material to the upper plate. The proposed emergence of the interplate boundary into the middle part of the wedge along the Lower Splay Fault, could have favoured the formation of the giant Sumatra tsunami at moderate water depth. This docking and temporary stacking of these volcanic ridges before their subduction at depth, is favoured by the strong oblique convergence that prevails up to the Bengal basin into the north.

Gasification of black liquor

DOEpatents

Kohl, A.L.

1987-07-28

A concentrated aqueous black liquor containing carbonaceous material and alkali metal sulfur compounds is treated in a gasifier vessel containing a relatively shallow molten salt pool at its bottom to form a combustible gas and a sulfide-rich melt. The gasifier vessel, which is preferably pressurized, has a black liquor drying zone at its upper part, a black liquor solids gasification zone located below the drying zone, and a molten salt sulfur reduction zone which comprises the molten salt pool. A first portion of an oxygen-containing gas is introduced into the gas space in the gasification zone immediately above the molten salt pool. The remainder of the oxygen-containing gas is introduced into the molten salt pool in an amount sufficient to cause gasification of carbonaceous material entering the pool from the gasification zone but not sufficient to create oxidizing conditions in the pool. The total amount of the oxygen-containing gas introduced both above the pool and into the pool constitutes between 25 and 55% of the amount required for complete combustion of the black liquor feed. A combustible gas is withdrawn from an upper portion of the drying zone, and a melt in which the sulfur content is predominantly in the form of alkali metal sulfide is withdrawn from the molten salt sulfur reduction zone. 2 figs.

Gasification of black liquor

DOEpatents

Kohl, Arthur L.

1987-07-28

A concentrated aqueous black liquor containing carbonaceous material and alkali metal sulfur compounds is treated in a gasifier vessel containing a relatively shallow molten salt pool at its bottom to form a combustible gas and a sulfide-rich melt. The gasifier vessel, which is preferably pressurized, has a black liquor drying zone at its upper part, a black liquor solids gasification zone located below the drying zone, and a molten salt sulfur reduction zone which comprises the molten salt pool. A first portion of an oxygen-containing gas is introduced into the gas space in the gasification zone immediatley above the molten salt pool. The remainder of the oxygen-containing gas is introduced into the molten salt pool in an amount sufficient to cause gasification of carbonaceous material entering the pool from the gasification zone but not sufficient to create oxidizing conditions in the pool. The total amount of the oxygen-containing gas introduced both above the pool and into the pool constitutes between 25 and 55% of the amount required for complete combustion of the black liquor feed. A combustible gas is withdrawn from an upper portion of the drying zone, and a melt in which the sulfur content is predominantly in the form of alkali metal sulfide is withdrawn from the molten salt sulfur reduction zone.

[Amyotrophy and neuronal depopulation of cerebral origin].

PubMed

Serratrice, G; Gastaut, J L; Pellissier, J F; Baret, J; Roux, H; Cartouzou, G

1975-03-01

Amyotrophy of cerebral origin was analyzed in 12 hemiplegics by means of comparative histological, histoenzymological, histographic and biochemical analysis of biopsies carried out in symmetrical zones. In the 6 cases in which atrophy predominated on the paralyzed side, it occurred early, the deficiency affecting the upper limb in particular and the sensory disturbance being irregular. Attempted numeration of the motor units remaining, according to the "incremential" method of stimulation, suggests a numerical reduction on the hemipelgic side. Despite reservations and general criticisms of this method, its comparative value, although approximate, must be acknowledged. However, although amyotrophy presumes a transsynaptic change in trophic function to have taken place in the peripheral neurone, neuronal depopulation--if one accepts it--cannot be other than functional.

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

Glagovskii, V. B.; Kassirova, N. A.; Turchina, O. A.

In designing stationary oil-gas recovery platforms on the continental shelf, the need arises to compute the estimated strength of their support base during seismic events. This paper is devoted to this estimation. The paper examines a structure consisting of the superstructure of an oil-gas platform and its gravity-type base. It is possible to install earthquake-insulating supports between them. Calculations performed for the design earthquake indicated that the design of the gravity base can resist a seismic effect without special additional measures. During the maximum design earthquake, moreover, significant stresses may develop in the zone of base where the columns aremore » connected to the upper slab of the caisson. In that case, the earthquake insulation considered for the top of the platform becomes critical.« less

The role of rock moisture on regulating hydrologic and solute fluxes in the critical zone

NASA Astrophysics Data System (ADS)

Rempe, D. M.; Druhan, J. L.; Hahm, W. J.; Wang, J.; Murphy, C.; Cargill, S.; Dietrich, W. E.; Tune, A. K.

2017-12-01

In environments where the vadose zone extends below the soil layer into underlying weathered bedrock, the water held in the weathering -generated pores can be an important source of moisture to vegetation. The heterogeneous distribution of pore space in weathered bedrock, furthermore, controls the subsurface water flowpaths that dictate how water is partitioned in the critical zone (CZ) and evolves geochemically. Here, we present the results of direct monitoring of the fluxes of water and solutes through the deep CZ using a novel vadose zone monitoring system (VMS) as well as geophysical logging and sampling in a network of deep wells across a steep hillslope in Northern California. At our study site (Eel River CZO), multi-year monitoring reveals that a significant fraction of incoming rainfall (up to 30%) is seasonally stored in the fractures and matrix of the upper 12 m of weathered bedrock as rock moisture. Intensive geochemical and geophysical observations distributed from the surface to the depth of unweathered bedrock indicate that the seasonal addition and depletion of rock moisture has key implications for hydrologic and geochemical processes. First, rock moisture storage provides an annually consistent water storage reservoir for use by vegetation during the summer, which buffers transpiration fluxes against variability in seasonal precipitation. Second, because the timing and magnitude of groundwater recharge and streamflow are controlled by the annual filling and drainage of the rock moisture, rock moisture regulates the partitioning of hydrologic fluxes. Third, we find that rock moisture dynamics—which influence the myriad geochemical and microbial processes that weather bedrock—strongly correspond with the observed vertical weathering profile. As a result of the coupling between chemical weathering reactions and hydrologic fluxes, the geochemical composition of groundwater and streamflow is influenced by the temporal dynamics of rock moisture. Our findings highlight the strong influence of water transport and storage dynamics in the weathered bedrock beneath the soil layer on catchment-scale hydrologic and geochemical fluxes, and underscore the need for further exploration of the fractured bedrock vadose zones common to many upland landscapes.

Forearc deformation and great subduction earthquakes: implications for cascadia offshore earthquake potential.

PubMed

McCaffrey, R; Goldfinger, C

1995-02-10

The maximum size of thrust earthquakes at the world's subduction zones appears to be limited by anelastic deformation of the overriding plate. Anelastic strain in weak forearcs and roughness of the plate interface produced by faults cutting the forearc may limit the size of thrust earthquakes by inhibiting the buildup of elastic strain energy or slip propagation or both. Recently discovered active strike-slip faults in the submarine forearc of the Cascadia subduction zone show that the upper plate there deforms rapidly in response to arc-parallel shear. Thus, Cascadia, as a result of its weak, deforming upper plate, may be the type of subduction zone at which great (moment magnitude approximately 9) thrust earthquakes do not occur.

How Many Convective Zones Are There in the Atmosphere of Venus?

NASA Astrophysics Data System (ADS)

Moroz, V. I.; Rodin, A. V.

2002-11-01

The qualitative characteristics of the vertical structure of the atmospheres of Venus and the Earth essentially differ. For instance, there are at least two, instead of one, zones with normal (thermal) convection on Venus. The first one is near the surface (a boundary layer); the second is at the altitudes of the lower part of the main cloud layer between 49 and 55 km. Contrary to the hypotheses proposed by Izakov (2001, 2002), the upper convective zone prevents energy transfer from the upper clouds to the subcloud atmosphere by ``anomalous turbulent heat conductivity.'' It is possible, however, that the anomalous turbulent heat conductivity takes part in the redistribution of the heat fluxes within the lower (subcloud) atmosphere.

Widespread gas hydrate instability on the upper U.S. Beaufort margin

NASA Astrophysics Data System (ADS)

Phrampus, Benjamin J.; Hornbach, Matthew J.; Ruppel, Carolyn D.; Hart, Patrick E.

2014-12-01

The most climate-sensitive methane hydrate deposits occur on upper continental slopes at depths close to the minimum pressure and maximum temperature for gas hydrate stability. At these water depths, small perturbations in intermediate ocean water temperatures can lead to gas hydrate dissociation. The Arctic Ocean has experienced more dramatic warming than lower latitudes, but observational data have not been used to study the interplay between upper slope gas hydrates and warming ocean waters. Here we use (a) legacy seismic data that constrain upper slope gas hydrate distributions on the U.S. Beaufort Sea margin, (b) Alaskan North Slope borehole data and offshore thermal gradients determined from gas hydrate stability zone thickness to infer regional heat flow, and (c) 1088 direct measurements to characterize multidecadal intermediate ocean warming in the U.S. Beaufort Sea. Combining these data with a three-dimensional thermal model shows that the observed gas hydrate stability zone is too deep by 100 to 250 m. The disparity can be partially attributed to several processes, but the most important is the reequilibration (thinning) of gas hydrates in response to significant (~0.5°C at 2σ certainty) warming of intermediate ocean temperatures over 39 years in a depth range that brackets the upper slope extent of the gas hydrate stability zone. Even in the absence of additional ocean warming, 0.44 to 2.2 Gt of methane could be released from reequilibrating gas hydrates into the sediments underlying an area of ~5-7.5 × 103 km2 on the U.S. Beaufort Sea upper slope during the next century.

Critical Zone Services as a Measure for Evaluating the Trade-offs in Intensively Managed Landscapes

NASA Astrophysics Data System (ADS)

Richardson, M.; Kumar, P.

2015-12-01

The Critical Zone includes the range of biophysical processes occurring from the top of the vegetation canopy to the weathering zone below the groundwater table. These services (Field et al. 2015) provide a measure to value processes that support the goods and services from our landscapes. In intensively managed landscapes the provisioning and regulating services are being altered through anthropogenic energy inputs so as to derive more agricultural productivity from the landscapes. Land use change and other alterations to the environment result in positive and/or negative net Critical Zone services. Through studies in the Critical Zone Observatory for Intensively Managed Landscapes (IMLCZO), this research seeks to answer questions such as: Are perennial bioenergy crops or annual replaced crops better for the land and surrounding environment? How do we evaluate the products and services from the land for the energy and resources we put in? Before the economic valuation of Critical Zone services, these questions seemed abstract. However, with developments such as Critical Zone services and life cycle assessments, they are more concrete. To evaluate the trade-offs between positive and negative impacts, life cycle assessments are used to create an inventory of all the energy inputs and outputs in a landscape management system. Total energy is computed by summing the mechanical energy used to construct tile drains, fertilizer, and other processes involved in intensely managed landscapes and the chemical energy gained by the production of biofuels from bioenergy crops. A multi-layer canopy model (MLCan) computes soil, water, and nutrient outputs for each crop type, which can be translated into Critical Zone services. These values are then viewed alongside the energy inputs into the system to show the relationship between agricultural practices and their corresponding ecosystem and environmental impacts.

Seismic evidence for water transport out of the mantle transition zone beneath the European Alps

NASA Astrophysics Data System (ADS)

Liu, Zhen; Park, Jeffrey; Karato, Shun-ichiro

2018-01-01

The mantle transition zone has been considered a major water reservoir in the deep Earth. Mass transfer across the transition-zone boundaries may transport water-rich minerals from the transition zone into the water-poor upper or lower mantle. Water release in the mantle surrounding the transition zone could cause dehydration melting and produce seismic low-velocity anomalies if some conditions are met. Therefore, seismic observations of low-velocity layers surrounding the transition zone could provide clues of water circulation at mid-mantle depths. Below the Alpine orogen, a depressed 660-km discontinuity has been imaged clearly using seismic tomography and receiver functions, suggesting downwellings of materials from the transition zone. Multitaper-correlation receiver functions show prominent ∼0.5-1.5% velocity reductions at ∼750-800-km depths, possibly caused by partial melting in the upper part of lower mantle. The gap between the depressed 660-km discontinuity and the low-velocity layers is consistent with metallic iron as a minor phase in the topmost lower mantle reported by laboratory studies. Velocity drops atop the 410-km discontinuity are observed surrounding the Alpine orogeny, suggesting upwelling of water-rich rock from the transition zone in response to the downwelled materials below the orogeny. Our results provide evidence that convective penetration of the mantle transition zone pushes hydrated minerals both upward and downward to add hydrogen to the surrounding mantle.

Hydropedology: Synergistic integration of soil science and hydrology in the Critical Zone

USGS Publications Warehouse

Lin, H.S.; McDonnell, J.J.; Nimmo, John R.; Pachepsky, Y. A.

2016-01-01

Soil and water are the two critical components of theEarth’s Critical Zone (Figure 1): Soil modulates the connection between bedrock and the atmospheric boundary layer and water is a major driving force and transport agent between these two zones. The interactions between soil and water are so intimate and complex that they cannot be effectively studied in a piecemeal manner; they require a systems approach. In this spirit, hydropedology has emerged in recent years as a synergistic integration of soil science and hydrology that offers a renewed perspective and an integrated approach to understanding interactive pedologic and hydrologic processes and their properties in the Critical Zone.

Three-dimensional models of deformation near strike-slip faults

USGS Publications Warehouse

ten Brink, Uri S.; Katzman, Rafael; Lin, J.

1996-01-01

We use three-dimensional elastic models to help guide the kinematic interpretation of crustal deformation associated with strike-slip faults. Deformation of the brittle upper crust in the vicinity of strike-slip fault systems is modeled with the assumption that upper crustal deformation is driven by the relative plate motion in the upper mantle. The driving motion is represented by displacement that is specified on the bottom of a 15-km-thick elastic upper crust everywhere except in a zone of finite width in the vicinity of the faults, which we term the "shear zone." Stress-free basal boundary conditions are specified within the shear zone. The basal driving displacement is either pure strike slip or strike slip with a small oblique component, and the geometry of the fault system includes a single fault, several parallel faults, and overlapping en echelon faults. We examine the variations in deformation due to changes in the width of the shear zone and due to changes in the shear strength of the faults. In models with weak faults the width of the shear zone has a considerable effect on the surficial extent and amplitude of the vertical and horizontal deformation and on the amount of rotation around horizontal and vertical axes. Strong fault models have more localized deformation at the tip of the faults, and the deformation is partly distributed outside the fault zone. The dimensions of large basins along strike-slip faults, such as the Rukwa and Dead Sea basins, and the absence of uplift around pull-apart basins fit models with weak faults better than models with strong faults. Our models also suggest that the length-to-width ratio of pull-apart basins depends on the width of the shear zone and the shear strength of the faults and is not constant as previously suggested. We show that pure strike-slip motion can produce tectonic features, such as elongate half grabens along a single fault, rotated blocks at the ends of parallel faults, or extension perpendicular to overlapping en echelon faults, which can be misinterpreted to indicate a regional component of extension. Zones of subsidence or uplift can become wider than expected for transform plate boundaries when a minor component of oblique motion is added to a system of parallel strike-slip faults.

Three-dimensional models of deformation near strike-slip faults

USGS Publications Warehouse

ten Brink, Uri S.; Katzman, Rafael; Lin, Jian

1996-01-01

We use three-dimensional elastic models to help guide the kinematic interpretation of crustal deformation associated with strike-slip faults. Deformation of the brittle upper crust in the vicinity of strike-slip fault systems is modeled with the assumption that upper crustal deformation is driven by the relative plate motion in the upper mantle. The driving motion is represented by displacement that is specified on the bottom of a 15-km-thick elastic upper crust everywhere except in a zone of finite width in the vicinity of the faults, which we term the “shear zone.” Stress-free basal boundary conditions are specified within the shear zone. The basal driving displacement is either pure strike slip or strike slip with a small oblique component, and the geometry of the fault system includes a single fault, several parallel faults, and overlapping en echelon faults. We examine the variations in deformation due to changes in the width of the shear zone and due to changes in the shear strength of the faults. In models with weak faults the width of the shear zone has a considerable effect on the surficial extent and amplitude of the vertical and horizontal deformation and on the amount of rotation around horizontal and vertical axes. Strong fault models have more localized deformation at the tip of the faults, and the deformation is partly distributed outside the fault zone. The dimensions of large basins along strike-slip faults, such as the Rukwa and Dead Sea basins, and the absence of uplift around pull-apart basins fit models with weak faults better than models with strong faults. Our models also suggest that the length-to-width ratio of pull-apart basins depends on the width of the shear zone and the shear strength of the faults and is not constant as previously suggested. We show that pure strike-slip motion can produce tectonic features, such as elongate half grabens along a single fault, rotated blocks at the ends of parallel faults, or extension perpendicular to overlapping en echelon faults, which can be misinterpreted to indicate a regional component of extension. Zones of subsidence or uplift can become wider than expected for transform plate boundaries when a minor component of oblique motion is added to a system of parallel strike-slip faults.

Crustal-scale shear zones and heterogeneous structure beneath the North Anatolian Fault Zone, Turkey, revealed by a high-density seismometer array

NASA Astrophysics Data System (ADS)

Kahraman, Metin; Cornwell, David G.; Thompson, David A.; Rost, Sebastian; Houseman, Gregory A.; Türkelli, Niyazi; Teoman, Uğur; Altuncu Poyraz, Selda; Utkucu, Murat; Gülen, Levent

2015-11-01

Continental scale deformation is often localised along strike-slip faults constituting considerable seismic hazard in many locations. Nonetheless, the depth extent and precise geometry of such faults, key factors in how strain is accumulated in the earthquake cycle and the assessment of seismic hazard, are poorly constrained in the mid to lower crust. Using a dense broadband network of 71 seismic stations with a nominal station spacing of 7 km in the vicinity of the 1999 Izmit earthquake we map previously unknown small-scale structure in the crust and upper mantle along this part of the North Anatolian Fault Zone (NAFZ). We show that lithological and structural variations exist in the upper, mid and lower crust on length scales of less than 10 km and less than 20 km in the upper mantle. The surface expression of the NAFZ in this region comprises two major branches; both are shown to continue at depth with differences in dip, depth extent and (possibly) width. We interpret a <10 km wide northern branch that passes downward into a shear zone that traverses the entire crust and penetrates the upper mantle to a depth of at least 50 km. The dip of this structure appears to decrease west-east from ∼90° to ∼65° to the north over a distance of 30 to 40 km. Deformation along the southern branch may be accommodated over a wider (>10 km) zone in the crust with a similar variation of dip but there is no clear evidence that this shear zone penetrates the Moho. Layers of anomalously low velocity in the mid crust (20-25 km depth) and high velocity in the lower crust (extending from depths of 28-30 km to the Moho) are best developed in the Armutlu-Almacik block between the two shear zones. A mafic lower crust, possibly resulting from ophiolitic obduction or magmatic intrusion, can best explain the coherent lower crustal structure of this block. Our images show that strain has developed in the lower crust beneath both northern and southern strands of the North Anatolian Fault. Our new high resolution images provide new insights into the structure and evolution of the NAFZ and show that a small and dense passive seismic network is able to image previously undetectable crust and upper mantle heterogeneity on lateral length scales of less than 10 km.

Provenance and geochronological insights into Late Cretaceous-Paleogene foreland basin development in the Subandean Zone and Oriente Basin of Ecuador

NASA Astrophysics Data System (ADS)

Gutierrez, E. G.; Horton, B. K.; Vallejo, C.

2017-12-01

The tectonic history of the Oriente foreland basin and adjacent Subandean Zone of Ecuador during contractional mountain building in the northern Andes can be revealed through integrated stratigraphic, geochronological, structural, and provenance analyses of clastic sediments deposited during orogenesis. We present new maximum depositional ages and a comprehensive provenance analysis for key stratigraphic units deposited in the western (proximal) Oriente Basin. Detrital zircon U-Pb ages were obtained from Upper Cretaceous and Cenozoic clastic formations from exposures in the Subandean Zone. The sampled stratigraphic intervals span critical timeframes during orogenesis in the Ecuadorian Andes. Cenozoic formations have poorly defined chronostratigraphic relationships and are therefore a primary target of this study. In addition, the newly acquired U-Pb age spectra allow clear identification of the various sediment source regions that fed the system during distinct depositional phases. Maximum depositional ages (MDA) were obtained for five samples from three formations: the Tena (MDA=69.6 Ma), Chalcana (MDA=29.3 Ma), and Arajuno (MDA= 17.1, 14.2, 12.8 Ma) Formations, placing them in the Maastrichtian, early Oligocene, and early-middle Miocene, respectively. Detrital zircon U-Pb ages identify clear signatures of at least four different sources: craton (1600-1300 Ma, 1250-900 Ma), Eastern Cordillera fold-thrust belt (600-450 Ma, 250-145 Ma), Western Cordillera magmatic arc (<88 Ma), and recycling of cratonic material from the Eastern Cordillera. The U-Pb age spectra of the Upper Cretaceous-Paleogene type sections allow us to recognize variations in the contribution of each recognized source over time. We identify recycled material with two dominant peak ages (1250-900 Ma and 600-450 Ma), material derived from the adjacent uplifted orogen or recycled from foredeep sediments incorporated into the deforming wedge. Finally, an apparent unroofing event is inferred from a 250-145 Ma age peak in the Plio-Pleistocene Mesa-Mera Formation revealing the persistent shortening deformation influencing the structural configuration and sediment dispersal patterns of the Oriente Basin and Subandean Zone.

Linkages Between the Megathrust and Upper-plate Deformation: Lessons From the Deformational Dichotomy of the 2016 Kaikoura New Zealand Earthquake

NASA Astrophysics Data System (ADS)

Furlong, K. P.; Herman, M. W.

2017-12-01

Following the 2016 Mw 7.8 Kaikoura earthquake, the nature of the coseismic rupture was unclear. Seismological and tsunami evidence pointed to significant involvement of the subduction megathrust, while geodetic and field observations pointed to a shallow set of intra-crustal faults as the main participants during the earthquake. It now appears that the Kaikoura earthquake produced synchronous faulting on the plate boundary subduction interface - the megathrust - and on a suite of crustal faults above the rupture zone in the overlying plate. This Kaikoura-style earthquake, involving synchronous ruptures on multiple components of the plate boundary, may be an important mode of plate boundary deformation affecting seismic hazard along subduction zones. Here we propose a model to explain how these upper-plate faults are loaded during the periods between megathrust earthquakes and subsequently can rupture synchronously with the megathrust. Between megathrust earthquakes, horizontal compression, driven by plate convergence, locks the upper-plate faults, particularly those at higher angles to the convergence direction and the oblique plate motion of the subducting Pacific plate deforms the upper-plate in bulk shear. During the time interval of megathrust rupture, two things happen which directly affect the stress conditions acting on these upper-plate faults: (1) slip on the megathrust and the associated `rebound' of the upper plate reduces the compressive or normal stress acting on the upper plate faults, and (2) the base of the upper plate faults (and the upper plate itself) is decoupled from the slab in the region above rupture area. The reduction in normal stress acting on these faults increases their Coulomb Stress state to strongly favor strike-slip fault slip, and the basal decoupling of the upper plate allows it to undergo nearly complete stress recovery in that region; enabling the occurrence of very large offsets on these faults - offsets that exceed the slip on the plate interface. With these results it is clear that the 2016 Kaikoura NZ earthquake represents a mode of subduction zone rupture that must be considered in other regions.

Reactor for fluidized bed silane decomposition

NASA Technical Reports Server (NTRS)

Iya, Sridhar K. (Inventor)

1989-01-01

An improved heated fluidized bed reactor and method for the production of high purity polycrystalline silicon by silane pyrolysis wherein silicon seed particles are heated in an upper heating zone of the reactor and admixed with particles in a lower zone, in which zone a silane-containing gas stream, having passed through a lower cooled gas distribution zone not conducive to silane pyrolysis, contacts the heated seed particles whereon the silane is heterogeneously reduced to silicon.

In-situ gas hydrate hydrate saturation estimated from various well logs at the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope

USGS Publications Warehouse

Lee, M.W.; Collett, T.S.

2011-01-01

In 2006, the U.S. Geological Survey (USGS) completed detailed analysis and interpretation of available 2-D and 3-D seismic data and proposed a viable method for identifying sub-permafrost gas hydrate prospects within the gas hydrate stability zone in the Milne Point area of northern Alaska. To validate the predictions of the USGS and to acquire critical reservoir data needed to develop a long-term production testing program, a well was drilled at the Mount Elbert prospect in February, 2007. Numerous well log data and cores were acquired to estimate in-situ gas hydrate saturations and reservoir properties.Gas hydrate saturations were estimated from various well logs such as nuclear magnetic resonance (NMR), P- and S-wave velocity, and electrical resistivity logs along with pore-water salinity. Gas hydrate saturations from the NMR log agree well with those estimated from P- and S-wave velocity data. Because of the low salinity of the connate water and the low formation temperature, the resistivity of connate water is comparable to that of shale. Therefore, the effect of clay should be accounted for to accurately estimate gas hydrate saturations from the resistivity data. Two highly gas hydrate-saturated intervals are identified - an upper ???43 ft zone with an average gas hydrate saturation of 54% and a lower ???53 ft zone with an average gas hydrate saturation of 50%; both zones reach a maximum of about 75% saturation. ?? 2009.

Microvascular reconstructive surgery in Operations Iraqi and Enduring Freedom: the US military experience performing free flaps in a combat zone.

PubMed

Klem, Christopher; Sniezek, Joseph C; Moore, Brian; Davis, Michael R; Coppit, George; Schmalbach, Cecelia

2013-08-01

Local nationals with complex wounds resulting from traumatic combat injuries during Operations Iraqi Freedom and Enduring Freedom usually must undergo reconstructive surgery in the combat zone. While the use of microvascular free-tissue transfer (free flaps) for traumatic reconstruction is well documented in the literature, various complicating factors exist when these intricate surgical procedures are performed in a theater of war. The microvascular experiences of six military surgeons deployed during a 30-month period between 2006 and 2011 in Iraq and Afghanistan were retrospectively reviewed. Twenty-nine patients presented with complex traumatic wounds. Thirty-one free flaps were performed for the 29 patients. Location of tissue defects included the lower extremity (15), face/neck (8), upper extremity (6). Limb salvage was successful in all but one patient. Six of eight patients with head and neck wounds were tolerating oral intake at the time of discharge. There were three flap losses in 3 patients; two patients who experienced flap loss underwent a successful second free or regional flap. Minor complications occurred in six patients. Microvascular free tissue transfer for complex tissue defects in a combat zone is a critically important task and can improve quality of life for host-nation patients. Major US combat hospitals deployed to a war zone should include personnel who are trained and capable of performing these complex reconstructive procedures and who understand the many nuances of optimizing outcomes in this challenging environment.

`Dhara': An Open Framework for Critical Zone Modeling

NASA Astrophysics Data System (ADS)

Le, P. V.; Kumar, P.

2016-12-01

Processes in the Critical Zone, which sustain terrestrial life, are tightly coupled across hydrological, physical, biological, chemical, pedological, geomorphological and ecological domains over both short and long timescales. Observations and quantification of the Earth's surface across these domains using emerging high resolution measurement technologies such as light detection and ranging (lidar) and hyperspectral remote sensing are enabling us to characterize fine scale landscape attributes over large spatial areas. This presents a unique opportunity to develop novel approaches to model the Critical Zone that can capture fine scale intricate dependencies across the different processes in 3D. The development of interdisciplinary tools that transcend individual disciplines and capture new levels of complexity and emergent properties is at the core of Critical Zone science. Here we introduce an open framework for high-performance computing model (`Dhara') for modeling complex processes in the Critical Zone. The framework is designed to be modular in structure with the aim to create uniform and efficient tools to facilitate and leverage process modeling. It also provides flexibility to maintain, collaborate, and co-develop additional components by the scientific community. We show the essential framework that simulates ecohydrologic dynamics, and surface - sub-surface coupling in 3D using hybrid parallel CPU-GPU. We demonstrate that the open framework in Dhara is feasible for detailed, multi-processes, and large-scale modeling of the Critical Zone, which opens up exciting possibilities. We will also present outcomes from a Modeling Summer Institute led by Intensively Managed Critical Zone Observatory (IMLCZO) with representation from several CZOs and international representatives.

Primary weathering rates, water transit times and concentration-discharge relations: A theoretical analysis for the critical zone

NASA Astrophysics Data System (ADS)

Ameli, Ali; Erlandsson, Martin; Beven, Keith; Creed, Irena; McDonnell, Jeffrey; Bishop, Kevin

2017-04-01

The permeability architecture of the critical zone exerts a major influence on the hydrogeochemistry of the critical zone. Water flowpath dynamics drive the spatio-temporal pattern of geochemical evolution and resulting streamflow concentration-discharge (C-Q) relation, but these flowpaths are complex and difficult to map quantitatively. Here, we couple a new integrated flow and particle tracking transport model with a general reversible Transition-State-Theory style dissolution rate-law to explore theoretically how C-Q relations and concentration in the critical zone respond to decline in saturated hydraulic conductivity (Ks) with soil depth. We do this for a range of flow rates and mineral reaction kinetics. Our results show that for minerals with a high ratio of equilibrium concentration to intrinsic weathering rate, vertical heterogeneity in Ks enhances the gradient of weathering-derived solute concentration in the critical zone and strengthens the inverse stream C-Q relation. As the ratio of equilibrium concentration to intrinsic weathering rate decreases, the spatial distribution of concentration in the critical zone becomes more uniform for a wide range of flow rates, and stream C-Q relation approaches chemostatic behaviour, regardless of the degree of vertical heterogeneity in Ks. These findings suggest that the transport-controlled mechanisms in the hillslope can lead to chemostatic C-Q relations in the stream while the hillslope surface reaction-controlled mechanisms are associated with an inverse stream C-Q relation. In addition, as the ratio of equilibrium concentration to intrinsic weathering rate decreases, the concentration in the critical zone and stream become less dependent on groundwater age (or transit time)

Primary weathering rates, water transit times, and concentration-discharge relations: A theoretical analysis for the critical zone

NASA Astrophysics Data System (ADS)

Ameli, Ali A.; Beven, Keith; Erlandsson, Martin; Creed, Irena F.; McDonnell, Jeffrey J.; Bishop, Kevin

2017-01-01

The permeability architecture of the critical zone exerts a major influence on the hydrogeochemistry of the critical zone. Water flow path dynamics drive the spatiotemporal pattern of geochemical evolution and resulting streamflow concentration-discharge (C-Q) relation, but these flow paths are complex and difficult to map quantitatively. Here we couple a new integrated flow and particle tracking transport model with a general reversible Transition State Theory style dissolution rate law to explore theoretically how C-Q relations and concentration in the critical zone respond to decline in saturated hydraulic conductivity (Ks) with soil depth. We do this for a range of flow rates and mineral reaction kinetics. Our results show that for minerals with a high ratio of equilibrium concentration (Ceq) to intrinsic weathering rate (Rmax), vertical heterogeneity in Ks enhances the gradient of weathering-derived solute concentration in the critical zone and strengthens the inverse stream C-Q relation. As CeqRmax decreases, the spatial distribution of concentration in the critical zone becomes more uniform for a wide range of flow rates, and stream C-Q relation approaches chemostatic behavior, regardless of the degree of vertical heterogeneity in Ks. These findings suggest that the transport-controlled mechanisms in the hillslope can lead to chemostatic C-Q relations in the stream while the hillslope surface reaction-controlled mechanisms are associated with an inverse stream C-Q relation. In addition, as CeqRmax decreases, the concentration in the critical zone and stream become less dependent on groundwater age (or transit time).

Eighth report of the Normandy Archaeological Project: 1975 excavations at the Eoff I site (40CF32), Aaron Shelton site (40CF69) and the Duke I site (40CF97)

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

Faulkner, C.H.; McCollough, C.R.

This report discusses the research conducted during the last full field season for the Normandy Archaeological Project. There was a deep sense of urgency to use all available resources to continue to test crucial hypotheses about subsistence and settlement patterns of the Middle Woodland and Mississippian cultures in the lower and upper reservoir zones. The most salient of these hypotheses were prehistoric agricultural societies in the upper Duck Valley, and exploitative strategies of prehistoric hunters and gatherers in the upper Duck Valley differed in the lower and upper reservoir zones. Since the early Mississippian Banks phase and the late Middlemore » Woodland Owl Hollow phase exhibited evidence for both food production and permanent settlement in the lower reservoir zone, a continued attempt was made to excavate those sites on which components of these two phase were found. Additional community pattern data and chronometric dates for the Banks phase were also sought since previously obtained radiocarbon assays indicated this was one of the earliest Mississippian cultures in the Middle South. The study of the origins and local development of this culture was also given priority status in Normandy Research. 145 refs., 33 figs., 94 tabs.« less

Process dominance shift in solute chemistry as revealed by long-term high-frequency water chemistry observations of groundwater flowing through weathered argillite underlying a steep forested hillslope

NASA Astrophysics Data System (ADS)

Kim, Hyojin; Bishop, James K. B.; Dietrich, William E.; Fung, Inez Y.

2014-09-01

Significant solute flux from the weathered bedrock zone - which underlies soils and saprolite - has been suggested by many studies. However, controlling processes for the hydrochemistry dynamics in this zone are poorly understood. This work reports the first results from a four-year (2009-2012) high-frequency (1-3 day) monitoring of major solutes (Ca, Mg, Na, K and Si) in the perched, dynamic groundwater in a 4000 m2 zero-order basin located at the Angelo Coast Range Reserve, Northern California. Groundwater samples were autonomously collected at three wells (downslope, mid-slope, and upslope) aligned with the axis of the drainage. Rain and throughfall samples, profiles of well headspace pCO2, vertical profiles and time series of groundwater temperature, and contemporaneous data from an extensive hydrologic and climate sensor network provided the framework for data analysis. All runoff at this soil-mantled site occurs by vertical unsaturated flow through a 5-25 m thick weathered argillite and then by lateral flows to the adjacent channel as groundwater perched over fresher bedrock. Driven by strongly seasonal rainfall, over each of the four years of observations, the hydrochemistry of the groundwater at each well repeats an annual cycle, which can be explained by two end-member processes. The first end-member process, which dominates during the winter high-flow season in mid- and upslope areas, is CO2 enhanced cation exchange reaction in the vadose zone in the more shallow conductive weathered bedrock. This process rapidly increases the cation concentrations of the infiltrated rainwater, which is responsible for the lowest cation concentration of groundwater. The second-end member process occurs in the deeper perched groundwater and either dominates year-round (at the downslope well) or becomes progressively dominant during low flow season at the two upper slope wells. This process is the equilibrium reaction with minerals such as calcite and clay minerals, but not with primary minerals, suggesting the critical role of the residence time of the water. Collectively, our measurements reveal that the hydrochemistry dynamics of the groundwater in the weathered bedrock zone is governed by two end-member processes whose dominance varies with critical zone structure, the relative importance of vadose versus groundwater zone processes, and thus with the seasonal variation of the chemistry of recharge and runoff.

Genetic implications of the trace element distribution pattern in the upper knox carbonate rocks, copper ridge district, East Tennessee

NASA Astrophysics Data System (ADS)

Churnet, Habte G.; Misra, Kula C.

1981-11-01

The Lower Ordovician, Upper Knox Group rocks (the Kingsport and Mascot formations) in the Copper Ridge district consist predominantly of fine-grained dolostones, medium and coarser grained dolostones, and limestones. Dolomite crystals of medium and coarser grained dolostones show up to eight cathodoluminescent zones of variable width and intensity. Electron microprobe analyses indicate that the zoning is related to variation in Fe/Mn ratios, the brighter luminescent zones corresponding to lower ratios. Superposed on this growth zoning is a compositional zoning characterized by a general increase in Fe from core to rim of individual dolomite crystals. Field and petrographic studies (Churnet, 1979; Churnet et al., 1981) indicate that the fine-grained dolostones formed in supratidal to upper intratidal environments, whereas the precursor lime muds of the limestones as well as of the medium and coarser grained dolostones formed in shallow subtidal to lower intertidal environments. The large areal extent of the dolostones must have required a regionally abundant source of Mg such as marine water. Yet, both limestones and dolostones have low Na and Sr contents suggestive of their formation in solutions more dilute than normal marine water. It is proposed that the fine-grained dolostones formed by aggradation of initially very fine-grained dolostones in presence of fresh water, and that the limestones stabilized and the medium and coarser grained dolostones formed in environments of mixed marine and fresh waters. Considered in the light of ordering of partition coefficients, such a mixing model can account for the observed correlation pattern of trace elements (especially, SMn and SrFe) as well as the Fe distribution in the zoned dolomite crystals. Variation of the partition coefficient of Mn due to fluctuations in the relative proportions of fresh and marine waters in the diagenetic solution may explain the different Fe/Mn ratios observed in the growth zones (luminescence bands) of zoned dolomite crystals.

[Distribution characteristics of dissolved oxygen and mechanism of hypoxia in the upper estuarine zone of the Daliaohe River].

PubMed

Yang, Li-Na; Li, Zheng-Yan; Zhang, Xue-Qing

2011-01-01

Based on field surveys in the upper estuarine zone of the Daliaohe River in Spring and Summer of 2009, the spatial and temporal distributions of dissolved oxygen were analyzed and the mechanism of hypoxia were preliminarily discussed. The results indicated that DO concentrations were higher in the river mouth and lower in the upper reaches, higher in surface layers and lower in bottom concerning its spatial distribution. For its temporal distribution, DO concentrations were higher in daytime and lower at night, higher in Spring and lower in Summer. The DO concentrations in the upper estuarine zone of the Daliaohe River in Summer ranged between 1.36-4.77 mg/L with an average of 3.44 mg/L. The concentrations in the lower reaches were higher with an average of 3.94 mg/L. A large hypoxia area was recorded in Summer in the upper reaches of the estuary starting from about 45 km away from the river gate with an average DO concentration of 2.33 mg/L and a minimum of 1.36 mg/L. The correlation analysis showed that DO concentration was significantly correlated with nutrients and permanganate index. Excessive discharge of nutrients and organic pollutants were, therefore, main factors causing hypoxia, and water column stratification due to temperature rise in Summer in surface layers led to further reduction of DO in bottom layers of the water.

Provenance of upper Triassic sandstone, southwest Iberia (Alentejo and Algarve basins): tracing variability in the sources

NASA Astrophysics Data System (ADS)

Pereira, M. F.; Ribeiro, C.; Gama, C.; Drost, K.; Chichorro, M.; Vilallonga, F.; Hofmann, M.; Linnemann, U.

2017-01-01

Laser ablation ICP-MS U-Pb analyses have been conducted on detrital zircon of Upper Triassic sandstone from the Alentejo and Algarve basins in southwest Iberia. The predominance of Neoproterozoic, Devonian, Paleoproterozoic and Carboniferous detrital zircon ages confirms previous studies that indicate the locus of the sediment source of the late Triassic Alentejo Basin in the pre-Mesozoic basement of the South Portuguese and Ossa-Morena zones. Suitable sources for the Upper Triassic Algarve sandstone are the Upper Devonian-Lower Carboniferous of the South Portuguese Zone (Phyllite-Quartzite and Tercenas formations) and the Meguma Terrane (present-day in Nova Scotia). Spatial variations of the sediment sources of both Upper Triassic basins suggest a more complex history of drainage than previously documented involving other source rocks located outside present-day Iberia. The two Triassic basins were isolated from each other with the detrital transport being controlled by two independent drainage systems. This study is important for the reconstruction of the late Triassic paleogeography in a place where, later, the opening of the Central Atlantic Ocean took place separating Europe from North America.

75 FR 53193 - Safety Zone; Mississippi River, Mile 427.3 to 427.5

Federal Register 2010, 2011, 2012, 2013, 2014

2010-08-31

... Zone; Mississippi River, Mile 427.3 to 427.5 AGENCY: Coast Guard, DHS. ACTION: Temporary final rule... River, Mile 427.3 to 427.5, extending the entire width of the river. This safety zone is needed to... 5, 2010 the City of Keithsburg will be conducting a fireworks display at mile 427.4 on the Upper...

The morphology, processes, and evolution of Monterey Fan: a revisit

USGS Publications Warehouse

Gardner, James V.; Bohannon, Robert G.; Field, Michael E.; Masson, Douglas G.

2010-01-01

Long-range (GLORIA) and mid-range (TOBI) sidescan imagery and seismic-reflection profiles have revealed the surface morphology and architecture of the complete Monterey Fan. The fan has not developed a classic wedge shape because it has been blocked for much of its history by Morro Fracture Zone. The barrier has caused the fan to develop an upper-fan and lower-fan sequence that are distinctly different from one another. The upper-fan sequence is characterized by Monterey and Ascension Channels and associated Monterey Channel-levee system. The lower-fan sequence is characterized by depositional lobes of the Ascension, Monterey, and Sur-Parkington-Lucia systems, with the Monterey depositional lobe being the youngest. Presently, the Monterey depositional lobe is being downcut because the system has reached a new, lower base level in the Murray Fracture Zone. A five-step evolution of Monterey Fan is presented, starting with initial fan deposition in the Late Miocene, about 5.5 Ma. This first stage was one of filling bathymetric lows in the oceanic basement in what was to become the upper-fan segment. The second stage involved filling the bathymetric low on the north side of Morro Fracture Zone, and probably not much sediment was transported beyond the fracture zone. The third stage witnessed sediment being transported around both ends of Morro Fracture Zone and initial sedimentation on the lower-fan segment. During the fourth stage Ascension Channel was diverted into Monterey Channel, thereby cutting off sedimentation to the Ascension depositional lobe.

Municipal water supplies in Lee County, Florida, 1974

USGS Publications Warehouse

O'Donnell, T. H.

1977-01-01

In 1974 the total pumpage for Lee County, Fla., municipal supplies reached 5,700 Mgal (million gallons annually), an increase of 54 percent over 1970 levels. Pumpage from individual sources included: Caloosahatchee River, 1,312 Mgal; water-table aquifer, 2,171 Mgal; the water-bearing zone in the Tamiami Formation, 340 Mgal; the water-bearing zone in the upper part of the Hawthorn Formation, 1,399 Mgal; the saline water zones in the lower part of the Hawthorn Formation and the Suwannee Limestone, 483 Mgal. Among the various sources, the water-table aquifer showed the greatest increase in municipal pumpage over 1970 levels (60 percent) while the saline zones in the lower part of the Hawthorn Formation and Suwannee Limestone showed the least (40 percent). Intensive pumpage from the water bearing zone in the upper part of the Hawthorn Formation has caused a progressive decline in water levels in wells tapping that zone. The quality of fresh ground water in areas unaffected by intrusion of saline water, generally meets all the recommended limits of the Environmental Protection Agency. The chemical treatment processes utilized by water plants in the county are generally effective in producing finished water that meets EPA preliminary drinking water standards. (Woodard-USGS)

Critical Transition in Critical Zone of Intensively Managed Landscapes

NASA Astrophysics Data System (ADS)

Kumar, P.

2017-12-01

Intensification of industrial agriculture has resulted in severe unintended global impacts, including degradation of arable land and eutrophication of receiving water bodies. Modern agricultural practices rely on significant direct and indirect human energy inputs, which have created imbalances between increased rates of biogeochemical processes related to production and background rates of natural processes. These imbalances have cascaded through the deep inter-dependencies between carbon, soil, water, nutrient and ecological processes, resulting in a critical transition of the Critical Zone and creating emergent dynamics and evolutionary trajectories. Understanding of these novel organization and function of the Critical Zone is vital for developing sustainable agricultural practices.

Magnetic Susceptibility and Mineral Zonations Controlled by Provenance in Loess along the Illinois and Central Mississippi River Valleys

USGS Publications Warehouse

Grimley, D.A.; Follmer, L.R.; McKay, E.D.

1998-01-01

Magnetic susceptibility (MS) patterns have proven useful for regional stratigraphic correlations of zones within thick, oxidized Peoria and Roxana Silts along the Illinois and Central Mississippi River valleys for more than 350 km. Variations in MS of C horizon loess are controlled by silt-sized magnetite content and are interpreted to reflect changes in sediment provenance due to fluctuations of the Superior and Lake Michigan glacier lobes and the diversion of the Mississippi River to its present course. Grain size distributions and scanning electron microscopic observations indicate that stratigraphic changes in MS are not significantly influenced by eolian sorting or diagenetic dissolution, respectively. Three compositional zones (lower, middle, and upper) are delineated within Peoria Silt which usually can be traced in the field by MS, the occurrence of clay beds, interstadial soils, and/or subtle color changes. These zones can be correlated with, but are generally of more practical use than, previously studied dolomite zones (McKay, 1977) or clay mineral zones (Frye et al., 1968). However, mineralogical analyses can help to substantiate zone boundaries when in question. MS and compositional zones may indirectly record a climatic signal, primarily through the effect that global cooling has had on ice lobe fluctuations in the Upper Mississippi drainage basin. ?? 1998 University of Washington.

Audio-frequency magnetotelluric imaging of the Hijima fault, Yamasaki fault system, southwest Japan

NASA Astrophysics Data System (ADS)

Yamaguchi, S.; Ogawa, Y.; Fuji-Ta, K.; Ujihara, N.; Inokuchi, H.; Oshiman, N.

2010-04-01

An audio-frequency magnetotelluric (AMT) survey was undertaken at ten sites along a transect across the Hijima fault, a major segment of the Yamasaki fault system, Japan. The data were subjected to dimensionality analysis, following which two-dimensional inversions for the TE and TM modes were carried out. This model is characterized by (1) a clear resistivity boundary that coincides with the downward projection of the surface trace of the Hijima fault, (2) a resistive zone (>500 Ω m) that corresponds to Mesozoic sediment, and (3) shallow and deep two highly conductive zones (30-40 Ω m) along the fault. The shallow conductive zone is a common feature of the Yamasaki fault system, whereas the deep conductor is a newly discovered feature at depths of 800-1,800 m to the southwest of the fault. The conductor is truncated by the Hijima fault to the northeast, and its upper boundary is the resistive zone. Both conductors are interpreted to represent a combination of clay minerals and a fluid network within a fault-related fracture zone. In terms of the development of the fluid networks, the fault core of the Hijima fault and the highly resistive zone may play important roles as barriers to fluid flow on the northeast and upper sides of the conductive zones, respectively.

Occurrence and use of ground water in the Venice-Englewood area, Sarasota and Charlotte counties, Florida

USGS Publications Warehouse

Sutcliffe, Horace; Thompson, Thomas H.

1983-01-01

In a 75-square-mile area of coastal Sarasota and Charlotte Counties, demand for water is increasing. Groundwater, the principal source of supply, is distributed largely by public water systems. Principal water-bearing formations in descending order, include the surficial aquifer, artesian zone 1 in the Tamiami Formation, zone 2 in the upper part of the Hawthorn Formation, zone 3 in the lower part of the Hawthorn Formation and upper part of the Tampa Limestone, and zones 4 and 5 which comprise the Floridan aquifer. The surficial aquifer, except near tidewater, provides limited supplies of freshwater to wells. Artesian zone 1 is the major aquifer for public supply. It is contaminated by saline water in some areas, either as a result of inundation by storm-driven tides or by upwar leakage of mineralized water from underlying aquifers through uncased or improperly constructed wells. The city of Venice obtains some water from zone 2, but the water is brackish in much of the area. The water is suitable for irrigation in parts of the area. Except for local use of water for watering livestock and maintaining ponds, the water from zones 3, 4, and 5 is little used because of its poor quality. (USGS)

Petrologic and chemical changes in ductile shear zones as a function of depth in the continental crust

NASA Astrophysics Data System (ADS)

Yang, Xin-Yue

Petrologic and geochemical changes in ductile shear zones are important for understanding deformational and geochemical processes of the continental crust. This study examines three shear zones that formed under conditions varying from lower greenschist facies to upper amphibolite facies in order to document the petrologic and geochemical changes of deformed rocks at various metamorphic grades. The studied shear zones include two greenschist facies shear zones in the southern Appalachians and an upper amphibolite facies shear zone in southern Ontario. The mylonitic gneisses and mylonites in the Roses Mill shear zone of central Virginia are derived from a ferrodiorite protolith and characterized by a lower greenschist facies mineral assemblage. Both pressure solution and recrystallization were operative deformation mechanisms during mylonitization in this shear zone. Strain-driven dissolution and solution transfer played an important role in the mobilization of felsic components (Si, Al, K, Na, and Ca). During mylonitization, 17% to 32% bulk rock volume losses of mylonites are mainly attributed to removal of these mobile felsic components by a fluid phase. Mafic components (Fe, Mg, Ti, Mn and P) and trace elements, REE, Y, V and Sc, were immobile. At Rosman, North Carolina, the Brevard shear zone (BSZ) shows a deformational transition from the coarse-grained Henderson augen gneiss (HAG) to proto-mylonite, mylonite and ultra-mylonite. The mylonites contain a retrograde mineral assemblage as a product of fluid-assisted chemical breakdown of K-feldspar and biotite at higher greenschist facies conditions. Recrystallization and intra-crystalline plastic deformation are major deformation mechanisms in the BSZ. Fluid-assisted mylonitization in the BSZ led to 6% to 23% bulk volume losses in mylonites. During mylonitization, both major felsic and mafic elements and trace elements, Rb, Sr, Zr, V, Sc, and LREE were mobile; however, the HREEs were likely immobile. A shear zone in the Parry Sound domain, Ontario, formed at upper amphibolite facies conditions. The deformation process of the shear zone involves fully plastic deformation and high-temperature dynamic recrystallization and annealing recovery of both quartz and plagioclase. Geochemical evidence indicates that the chemical changes in the deformed rocks resulted from mixing of mafic and felsic layers together with fluid-assisted mass transfer within the shear zone. A geochemical model that incorporates closed-system two-component mixing with open-system mass transfer can well explain the observed major and trace element data.

Physical and chemical controls on the critical zone

USGS Publications Warehouse

Anderson, S.P.; Von Blanckenburg, F.; White, A.F.

2007-01-01

Geochemists have long recognized a correlation between rates of physical denudation and chemical weathering. What underlies this correlation? The Critical Zone can be considered as a feed-through reactor. Downward advance of the weathering front brings unweathered rock into the reactor. Fluids are supplied through precipitation. The reactor is stirred at the top by biological and physical processes. The balance between advance of the weathering front by mechanical and chemical processes and mass loss by denudation fixes the thickness of the Critical Zone reactor. The internal structure of this reactor is controlled by physical processes that create surface area, determine flow paths, and set the residence time of material in the Critical Zone. All of these impact chemical weathering flux.

Rivers of the Andes and the Amazon Basin: Deciphering global change from the hydroclimatic variability in the critical zone

NASA Astrophysics Data System (ADS)

Moreira-Turcq, Patricia; Carlo Espinoza, Jhan; Filizola, Naziano; Martinez, Jean-Michel

2018-01-01

The Critical Zone has been defined as the thin layer of the continental surfaces extending from fresh bedrock and the bottom of groundwater up to vegetation canopy, where soil, rock, water, air, and living organisms interact (Banwart et al., 2012; Lin et al., 2011). Despite the Critical Zone's importance to terrestrial life, it remains poorly understood. In this context, understanding the complex interactions between physical, chemical, and biological processes of the Critical Zone requires long-term observations (Anderson et al., 2012; Brantley et al., 2017), not only because different mechanisms have varying time frames, but also because it is necessary to monitor its natural and anthropogenic evolution in response to global climate and environmental changes.

IML-CZO: Critical Zone Observatory for Intensively Managed Landscapes

NASA Astrophysics Data System (ADS)

Kumar, Praveen; Papanicolaou, Thanos

2014-05-01

Intensively managed landscapes, regions of significant land use change, serve as a cradle for economic prosperity. However, the intensity of change is responsible for unintended deterioration of our land and water environments. By understanding present day dynamics in the context of long-term co-evolution of the Critical Zone comprising of the landscape, soil and biota, IML-CZO aims to support the assessment of short- and long-term resilience of the crucial ecological, hydrological and climatic services provided by the Critical Zone. An observational network of three sites in Illinois, Iowa, and Minnesota that capture the geological diversity of the low relief, glaciated, and tile-drained landscape will drive novel scientific and technological advances. IML-CZO will provide leadership in developing the next generation of scientists and practitioners, and informing management strategies aimed at reducing the vulnerability of the system to present and emerging trends in human activities. IML-CZO, one of the nine observatories funded by the United States National Science Foundation (NSF), consists of two core sites: the 3,690- sq. km. Upper Sangamon River Basin in Illinois and 270-sq. km. Clear Creek Watershed in Iowa, along with the 44,000- sq. km. Minnesota River Basin as third participating site. These sites together are characterized by low-relief landscapes with poorly drained soils and represent a broad range of physiographic variations found throughout the glaciated Midwest, and thereby provide an opportunity to advance understanding of the CZO in this important region. Through novel measurements, analysis and modeling, IML-CZO aims to address the following questions: • How do different time scales of geologic evolution and anthropogenic influence interact to determine the trajectory of CZ structure and function? • How is the co-evolution of biota, consisting of both vegetation and microbes, and soil affected due to intensive management? • How have dynamic patterns of connectivity, which link across transition zones and heterogeneity, changed by anthropogenic impacts? • How do these changes affect residence times and aggregate fluxes of water, carbon, nutrients, and sediment? IML-CZO will use historical data, existing observational networks, new instruments, remote sensing, sampling and laboratory analyses, and novel sensing technologies using open hardware and unmanned vehicles to study a number of variables related to climate and weather, hydrology, geology, geomorphology, soils, water chemistry, biogeochemistry, ecology, and land management. Additional details are available at imlczo.org.

Crustal-scale magmatism and its control on the longevity of magmatic systems

NASA Astrophysics Data System (ADS)

Karakas, Ozge; Degruyter, Wim; Bachmann, Olivier; Dufek, Josef

2017-04-01

Constraining the duration and evolution of crustal magma reservoirs is crucial to our understanding of the eruptive potential of magmatic systems, as well as the volcanic:plutonic ratios in the crust, but estimates of such parameters vary widely in the current literature. Although no consensus has been reached on the lifetime of magma reservoirs, recent studies have revealed about the presence, location, and melt fraction of multi-level (polybaric) storage zones in the crust. If magma accumulates at different crustal levels, it must redistribute significant enthalpy within the crustal column and therefore must influence the lifetime of magma plumbing systems. However, an evaluation of the mass and heat budget of the entire crustal column is lacking. Here, we use a two-dimensional thermal model to determine the thermal conditions under which both lower and upper crustal magma bodies form. We find that large lower crustal mush zones supply heat to the upper crust and reduce the amount of thermal energy necessary to form subvolcanic reservoirs. This indicates that the crust is thermally viable to sustain partially molten magma reservoirs over long timescales (>10^5-106 yr) for a range of magma fluxes (10^-4 to 10^-2 km^3/yr). Our results reconcile physical models of crustal magma evolution and field-based estimates of intrusion rates in numerous magmatic provinces (which include both volcanic and plutonic lithologies). We also show that young magmatic provinces (< 105 yr old) are unlikely to support large upper crustal reservoirs, whereas longer-lived systems (> 106 yr) can accumulate magma and build reservoirs capable of triggering supereruptions, even with intrusion rates as low as ≤10^-2 km^3/yr. Hence, the total duration of magmatism is critical in determining the size of the magma reservoirs, and should be combined with the magma intrusions rates to assess the capability of volcanic systems to form the largest eruptions on Earth.

Evidence for fluid and melt generation in response to an asthenospheric upwelling beneath the Hangai Dome, Mongolia

NASA Astrophysics Data System (ADS)

Comeau, Matthew J.; Käufl, Johannes S.; Becken, Michael; Kuvshinov, Alexey; Grayver, Alexander V.; Kamm, Jochen; Demberel, Sodnomsambuu; Sukhbaatar, Usnikh; Batmagnai, Erdenechimeg

2018-04-01

The Hangai Dome, Mongolia, is an unusual high-elevation, intra-continental plateau characterized by dispersed, low-volume, intraplate volcanism. Its subsurface structure and its origin remains unexplained, due in part to a lack of high-resolution geophysical data. Magnetotelluric data along a ∼610 km profile crossing the Hangai Dome were used to generate electrical resistivity models of the crust and upper mantle. The crust is found to be unexpectedly heterogeneous. The upper crust is highly resistive but contains several features interpreted as ancient fluid pathways and fault zones, including the South Hangai fault system and ophiolite belt that is revealed to be a major crustal boundary. South of the Hangai Dome a clear transition in crustal properties is observed which reflects the rheological differences across accreted terranes. The lower crust contains discrete zones of low-resistivity material that indicate the presence of fluids and a weakened lower crust. The upper mantle contains a large low-resistivity zone that is consistent with the presence of partial melt within an asthenospheric upwelling, believed to be driving intraplate volcanism and supporting uplift.

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.

Improved Nazca slab structure from teleseismic P-wave tomography along the Andean margin

NASA Astrophysics Data System (ADS)

Portner, D. E.; Beck, S. L.; Scire, A. C.; Zandt, G.

2017-12-01

South America marks the longest continuous ocean-continent subduction zone. As such, there is significant along-strike variability in the subducting Nazca slab structure and the tectonics of the South American margin. Most notably two gaps in the otherwise continuous volcanic arc are correlated with regions of flat slab subduction, indicating that the structure of the Nazca slab plays a controlling role in South American tectonics. Traditionally in subduction zones, our knowledge of slab structure is defined by Wadati-Benioff zone earthquakes. While this method allows for the determination of large-scale variations in Nazca slab structure such as regions of flat slab subduction, a scarcity of intermediate-depth earthquakes hinders our ability to observe the smaller-scale structural variations in the slab that may be critical to our understanding of the geologic record. We use an updated, larger dataset for finite-frequency teleseismic P-wave tomography including relative arrival times from >700 seismic stations along the Andean margin to image the detailed Nazca slab structure throughout the upper mantle and uppermost lower mantle between latitudes 5°S and 45°S. Our results show prominent variations in slab character along the margin. Slab dip varies significantly, from sub-vertical inboard of the Peruvian flat slab segment to 30° dip south of the Pampean flat slab, while the slab's velocity anomaly amplitude changes dramatically near the Pampean flat slab region. High slab velocities north of the Pampean region relative to the south indicate variable slab thermal structures that correspond roughly with the locations of deep (>500 km depth) earthquakes that also occur exclusively north of the Pampean region. Additionally, a wider regional footprint increases our sampling of the upper-lower mantle boundary, improving constraints on the slab's interaction with the 660 km discontinuity along strike. We see that the Nazca slab appears to penetrate into the lower mantle along the majority of the margin.

Results of borehole geophysical logging and aquifer-isolation tests conducted in the John Wagner and Sons, Inc. former production well, Ivyland, Pennsylvania

USGS Publications Warehouse

Sloto, Ronald A.

1997-01-01

A suite of borehole geophysical logs and heat-pulse-flowmeter measurements run in the former production well at the John Wagner and Sons, Inc. plant indicate two zones of borehole flow. In the upper part of the well, water enters the borehole through a fracture at 90 ft (feet) below floor level, moves upward, and exits the borehole through a fracture at 72 ft below floor level. Water also enters the borehole through fractures at 205-213, 235, and 357 ft below floor level; moves downward; and exits the borehole through fractures at 450-459, 468-470, and 483-490 ft below floor level. Five zones were selected for aquifer-isolation (packer) tests on the basis of borehole geophysical logs. The zones were isolated using a straddle-packer assembly. The lowermost three zones (below 248, 223 to 248, and 198 to 223 ft below floor level) were hydraulically isolated from zones above and below. Specific capacities were 0.12, 0.034, and 0.15 gallons per minute per foot, respectively. The hydrograph from zone 2 (223 to 248 ft below floor level) showed interference from a nearby pumping well. For the upper two zones (81 to 106 and 57 to 81 ft below floor level), similar drawdowns in the isolated zone and the zones above and below the isolated zone indicate that these fractures are hydraulically connected outside the borehole in the unconfined part of the Stockton Formation. The specific capacity of zones 4 and 5 are similar—0.82 and 0.61, respectively.

Widespread gas hydrate instability on the upper U.S. Beaufort margin

USGS Publications Warehouse

Phrampus, Benjamin J.; Hornbach, Matthew J.; Ruppel, Carolyn D.; Hart, Patrick E.

2014-01-01

The most climate-sensitive methane hydrate deposits occur on upper continental slopes at depths close to the minimum pressure and maximum temperature for gas hydrate stability. At these water depths, small perturbations in intermediate ocean water temperatures can lead to gas hydrate dissociation. The Arctic Ocean has experienced more dramatic warming than lower latitudes, but observational data have not been used to study the interplay between upper slope gas hydrates and warming ocean waters. Here we use (a) legacy seismic data that constrain upper slope gas hydrate distributions on the U.S. Beaufort Sea margin, (b) Alaskan North Slope borehole data and offshore thermal gradients determined from gas hydrate stability zone thickness to infer regional heat flow, and (c) 1088 direct measurements to characterize multidecadal intermediate ocean warming in the U.S. Beaufort Sea. Combining these data with a three-dimensional thermal model shows that the observed gas hydrate stability zone is too deep by 100 to 250 m. The disparity can be partially attributed to several processes, but the most important is the reequilibration (thinning) of gas hydrates in response to significant (~0.5°C at 2σ certainty) warming of intermediate ocean temperatures over 39 years in a depth range that brackets the upper slope extent of the gas hydrate stability zone. Even in the absence of additional ocean warming, 0.44 to 2.2 Gt of methane could be released from reequilibrating gas hydrates into the sediments underlying an area of ~5–7.5 × 103 km2 on the U.S. Beaufort Sea upper slope during the next century.

What's so critical about the critical zone?: New insights at the boundaries between hydrology, pedology, geomorphology, rocks and life (Invited)

NASA Astrophysics Data System (ADS)

Grant, G.

2013-12-01

The great promise of critical zone science and observatories (CZOs) emerging over the past decade was that real progress towards understanding the earth's near-surface environment could be made through coordinated studies of processes and interactions that occur within that thin layer between the bottom of the atmosphere and the top of competent bedrock - the critical zone. How well has this promise been realized, and where is the science now headed? Drawing on recent findings from CZOs and elsewhere, I identify a number of exciting and potentially transformative new ideas and threads at the boundaries of hydrology, geomorphology, pedology, and ecology. These include: 1). New understanding of interactions and feedbacks among soil weathering, pathways for water, tree roots, and bedrock fractures. A fundamental insight emerging from critical zone studies is that soils are far more interestingly structured than simple textbook models of homogeneous substrates with exponentially decreasing permeability with depth. Instead, the near-surface is now seen as a complex network of voids, paths, conduits, and storage zones that are both formed and exploited by the movement of water, geochemical reactions, and organisms. This evolving perspective on the critical zone has implications for a wide range of issues, including the residence time and chemistry of water, rates of weathering, slope stability, and long-term soil fertility. 2. Growing appreciation for the role of biology in conditioning and transforming its own physical environment within the critical zone. This includes the role of trees in hydraulically redistributing water, fracturing bedrock, and contributing to long-term soil erosion and landscape evolution through tree fall and throw and vegetation effects on moisture regimes. 3. Similarly, the importance of understanding linkages among soils, water, and vegetation has never been greater as a warming climate dramatically changes the 'rules of the game'. New understanding of feedbacks among vegetation growth and water uptake, soil moisture regimes, snowpack dynamics, and overall forest health are challenging previous assumptions about how best to manage forest environments in the face of a warming atmosphere and increased frequencies of disturbance. Time will tell whether these new perspectives represent incremental or fundamental shifts in our thinking about the critical zone, but it is clearly an exciting time for critical zone science and scientists.

Using an Integrated Hydrologic Model to Assess the Ecohydrological Impacts of Change on a Mountain Headwaters Critical Zone

NASA Astrophysics Data System (ADS)

Collins, C.; Maxwell, R. M.; Visser, A.

2016-12-01

The critical zone is the region of the Earth's crust where hydrogeology, ecology, and climate interact. As many critical zone processes are fundamental, the significance of studying critical zone processes goes beyond understanding the local ecohydrological setting. Therefore studying critical zone governing processes requires an interdisciplinary approach that integrates simulation and observation. In this study, a high-resolution integrated hydrologic model, ParFlow-CLM, was developed for the Providence Creek watershed. Providence Creek is a highly instrumented critical zone observatory (CZO) located in the southern Sierra Nevada Mountains, a region currently experiencing a range of short-term responses (i.e. tree mortality) to a severe four-year drought. Sources of plant water use, pathways and residence times of water through the subsurface are identified using a suite of isotopic signatures and numerical particle tracking. Implications of using a fully coupled integrated hydrologic model accompanied by tracer analysis include better understanding of water partitioning and water storage in the regolith and vegetation water use during drought time conditions. The importance of subsurface storage, plant available water and lateral flow during the 2012-2015 drought to mitigate vegetation stress are addressed and verified against observed tree mortality. The stream flow response to tree mortality in the aftermath of the drought, analogous to the Colorado Mountain Pine Beetle case, provides insight into the potential effects of proposed forest management practices.

Seismic Structure of the Antarctic Upper Mantle and Transition Zone Unearthed by Full Waveform Adjoint Tomography

NASA Astrophysics Data System (ADS)

Lloyd, A. J.; Wiens, D.; Zhu, H.; Tromp, J.; Nyblade, A.; Anandakrishnan, S.; Aster, R. C.; Huerta, A. D.; Winberry, J. P.; Wilson, T. J.; Dalziel, I. W. D.; Hansen, S. E.; Shore, P.

2017-12-01

The upper mantle and transition zone beneath Antarctica and the surrounding ocean are among the poorest seismically imaged regions of the Earth's interior. Over the last 1.5 decades researchers have deployed several large temporary broadband seismic arrays focusing on major tectonic features in the Antarctic. The broader international community has also facilitated further instrumentation of the continent, often operating stations in additional regions. As of 2016, waveforms are available from almost 300 unique station locations. Using these stations along with 26 southern mid-latitude seismic stations we have imaged the seismic structure of the upper mantle and transition zone using full waveform adjoint techniques. The full waveform adjoint inversion assimilates phase observations from 3-component seismograms containing P, S, Rayleigh, and Love waves, including reflections and overtones, from 270 earthquakes (5.5 ≤ Mw ≤ 7.0) that occurred between 2001-2003 and 2007-2016. We present the major results of the full waveform adjoint inversion following 20 iterations, resulting in a continental-scale seismic model (ANT_20) with regional-scale resolution. Within East Antarctica, ANT_20 reveals internal seismic heterogeneity and differences in lithospheric thickness. For example, fast seismic velocities extending to 200-300 km depth are imaged beneath both Wilkes Land and the Gamburtsev Subglacial Mountains, whereas fast velocities only extend to 100-200 km depth beneath the Lambert Graben and Enderby Land. Furthermore, fast velocities are not found beneath portions of Dronning Maud Land, suggesting old cratonic lithosphere may be absent. Beneath West Antarctica slow upper mantle seismic velocities are imaged extending from the Balleny Island southward along the Transantarctic Mountains front, and broaden beneath the southern and northern portion of the mountain range. In addition, slow upper mantle velocities are imaged beneath the West Antarctic coast extending from Marie Byrd Land to the Antarctic Peninsula. This region of slow velocity only extends to 150-200 km depth beneath the Antarctic Peninsula, while elsewhere it extends to deeper upper mantle depths and possibly into the transition zone as well as offshore, suggesting two different geodynamic processes are at play.

Effect of the focal plane position on CO2 laser beam cutting of injection molded polycarbonate sheets

NASA Astrophysics Data System (ADS)

Moradi, Mahmoud; Mehrabi, Omid; Azdast, Taher; Benyounis, Khaled Y.

2016-11-01

In the present research, the effect of laser beam focal plane position (FPP) on the kerf quality of the polycarbonate laser cutting is investigated. Low power CO2 laser is used as the heat source of the cutting runs. In the experiments, FPP is varied from 0 to -4mm while other processing parameters (i.e. laser power, cutting speed and gas pressure) are considered constant. Upper and lower kerf width, kerf taper, upper heat affected zone and surface roughness of the kerf wall are also considered as the responses. Observations signified that reducing the position of the laser beam focal point from zero to - 3mm reduces the upper and lower kerf width. However reducing FPP below -3mm leads to an increase in the kerf width. Results also reveals that upper heat affected zone value reduces by reduction in FPP. Moreover the best kerf wall surface roughness occurred at FPP= -3mm.

Scaly fabrics and veins of the Mugi and Makimine mélanges in the Shimanto belt, SW Japan

NASA Astrophysics Data System (ADS)

Ramirez, G. E.; Fisher, D. M.; Yamaguchi, A.; Kimura, G.

2016-12-01

Two regionally extensive ancient subduction fault zones provide a microstructural record of the plate boundary deformation associated with underthrusting. These rocks exhibit many of the characteristics associated with exposed ancient subduction fault zones worldwide, including: (1) σ1 is near orthogonal to the deformation fabric (2) there are microstructurally pervasive quartz and calcite filled veins concentrated in coarser blocks and along extensional jogs on slip surfaces, (3) evidence for local diffusion of silica sourced from web-like arrays of slip surfaces (i.e., scaly fabrics), and (4) evidence for cycles of cracking and sealing that record cyclic variations in stress. We present new backscatter SEM observations of scaly fabrics from two ancient subduction-related shear zones from the Shimanto Belt in Japan that exemplify these characteristics and represent the full temperature range of the seismogenic zone: 1) the Mugi mélange (lower ( 130-150 °C) and upper ( 170-200 °C) sections) and 2) Makimine mélange (peak temperatures of 340 °C). The Mugi mélange is an underplated duplex consisting of two horses separated by an OOST. The upper section is bounded at the top by a pseudotachylite-bearing paleodécollement. The Makimine mélange was underplated at the downdip limit of the seismogenic zone. The scaly fabrics associated with these shear zones display significantly different microstructural characteristics. A slip surface from along the upper Mugi is characterized by broader ( 20-30 μm), zones of quartz-poor, anastomosing shear zones composed of fine-grained (0.5-2 μm in length) phyllosilicates. The Makimine mélange exhibits thinner (10-20 μm), anastomosing shear zones with coarser (1-4 μm in length) phyllosilicate grains that are more strongly oriented into parallelism with slip surfaces. Quartz veins are pervasively developed in more competent blocks and are oriented at near perpendicular angles to the slip surfaces. Microstructural analyses of ancient subduction-related faults show differences with temperature that highlight the importance of establishing the geochemical processes and activation energies that contribute to slip, fracturing, and healing of rocks that underthrust the subduction interface.

Geophysical characteristics of the hydrothermal systems of Kilauea volcano, Hawaii

USGS Publications Warehouse

Kauahikaua, J.

1993-01-01

Clues to the overall structure of Kilauea volcano can be obtained from spatial studies of gravity, magnetic, and seismic velocity variations. The rift zones and summit are underlain by dense, magnetic, high P-wave-velocity rocks at depths of about 2 km less. The gravity and seismic velocity studies indicate that the rift structures are broad, extending farther to the north than to the south of the surface features. The magnetic data give more definition to the rift structures by allowing separation into a narrow, highly-magnetized, shallow zone and broad, flanking, magnetic lows. The patterns of gravity, magnetic variations, and seismicity document the southward migration of the upper cast rift zone. Regional, hydrologic features of Kilauea can be determined from resistivity and self-potential studies. High-level groundwater exists beneath Kilauea summit to elevations of +800 m within a triangular area bounded by the west edge of the upper southwest rift zone, the east edge of the upper east rift zone, and the Koa'c fault system. High-level groundwater is present within the east rift zone beyond the triangular summit area. Self-potential mapping shows that areas of local heat produce local fluid circulation in the unconfined aquifer (water table). The dynamics of Kilauea eruptions are responsible for both the source of heat and the fracture permeability of the hydrothermal system. Shallow seismicity and surface deformation indicate that magma is intruding and that fractures are forming beneath the rift zones and summit area. Magma supply estimates are used to calculate the rate of heat input to Kilauea's hydrothermal systems. Heat flows of 370-820 mW/m2 are calculated from deep wells within the lower east rift zone. The estimated heat input rate for Kilauea of 9 gigawatts (GW) is at least 25 times higher than the conductive heat loss as estimated from the heat flow in wells extrapolated over the area of the summit caldera and rift zones. Heat must be dissipated by another mechanism, or the heat input rate estimates are much too high. ?? 1993.

Oblique reactivation of lithosphere-scale lineaments controls rift physiography - the upper-crustal expression of the Sorgenfrei-Tornquist Zone, offshore southern Norway

NASA Astrophysics Data System (ADS)

Phillips, Thomas B.; Jackson, Christopher A.-L.; Bell, Rebecca E.; Duffy, Oliver B.

2018-04-01

Pre-existing structures within sub-crustal lithosphere may localise stresses during subsequent tectonic events, resulting in complex fault systems at upper-crustal levels. As these sub-crustal structures are difficult to resolve at great depths, the evolution of kinematically and perhaps geometrically linked upper-crustal fault populations can offer insights into their deformation history, including when and how they reactivate and accommodate stresses during later tectonic events. In this study, we use borehole-constrained 2-D and 3-D seismic reflection data to investigate the structural development of the Farsund Basin, offshore southern Norway. We use throw-length (T-x) analysis and fault displacement backstripping techniques to determine the geometric and kinematic evolution of N-S- and E-W-striking upper-crustal fault populations during the multiphase evolution of the Farsund Basin. N-S-striking faults were active during the Triassic, prior to a period of sinistral strike-slip activity along E-W-striking faults during the Early Jurassic, which represented a hitherto undocumented phase of activity in this area. These E-W-striking upper-crustal faults are later obliquely reactivated under a dextral stress regime during the Early Cretaceous, with new faults also propagating away from pre-existing ones, representing a switch to a predominantly dextral sense of motion. The E-W faults within the Farsund Basin are interpreted to extend through the crust to the Moho and link with the Sorgenfrei-Tornquist Zone, a lithosphere-scale lineament, identified within the sub-crustal lithosphere, that extends > 1000 km across central Europe. Based on this geometric linkage, we infer that the E-W-striking faults represent the upper-crustal component of the Sorgenfrei-Tornquist Zone and that the Sorgenfrei-Tornquist Zone represents a long-lived lithosphere-scale lineament that is periodically reactivated throughout its protracted geological history. The upper-crustal component of the lineament is reactivated in a range of tectonic styles, including both sinistral and dextral strike-slip motions, with the geometry and kinematics of these faults often inconsistent with what may otherwise be inferred from regional tectonics alone. Understanding these different styles of reactivation not only allows us to better understand the influence of sub-crustal lithospheric structure on rifting but also offers insights into the prevailing stress field during regional tectonic events.

Least-cost control of agricultural nutrient contributions to the Gulf of Mexico hypoxic zone.

PubMed

Rabotyagov, Sergey; Campbell, Todd; Jha, Manoj; Gassman, Philip W; Arnold, Jeffrey; Kurkalova, Lyubov; Secchi, Silvia; Feng, Hongli; Kling, Catherine L

2010-09-01

In 2008, the hypoxic zone in the Gulf of Mexico, measuring 20 720 km2, was one of the two largest reported since measurement of the zone began in 1985. The extent of the hypoxic zone is related to nitrogen and phosphorous loadings originating on agricultural fields in the upper Midwest. This study combines the tools of evolutionary computation with a water quality model and cost data to develop a trade-off frontier for the Upper Mississippi River Basin specifying the least cost of achieving nutrient reductions and the location of the agricultural conservation practices needed. The frontier allows policymakers and stakeholders to explicitly see the trade-offs between cost and nutrient reductions. For example, the cost of reducing annual nitrate-N loadings by 30% is estimated to be US$1.4 billion/year, with a concomitant 36% reduction in P and the cost of reducing annual P loadings by 30% is estimated to be US$370 million/year, with a concomitant 9% reduction in nitrate-N.

Effects of the types of overlap on the mechanical properties of FSSW welded AZ series magnesium alloy joints

NASA Astrophysics Data System (ADS)

Wang, Dan; Shen, Jun; Wang, Lin-Zhi

2012-03-01

The effects of the types of overlap on the mechanical properties of the friction stir spot welding (FSSW) welded AZ series magnesium alloy joints were investigated by microstructural observations, microhardness tests, and tensile tests. The results show that the microstructure of the stir zone adjacent to the periphery of the rotating pin is mainly composed of the upper sheet. The average distance D between the longitudinal segment of the curved interface and the keyhole periphery, the tensile shear force, and the microhardness of the stir zone of the FSSW welded AZ61 alloy joint are the highest in all samples. During FSSW of AZ31 and AZ61 dissimilar magnesium alloys, the irregular deformation of the longitudinal segment of the curved interface appears, while the microhardness of the stir zone is higher when AZ61 alloy is the upper sheet. Moreover, the microhardness of the stir zone increases initially and then decreases sharply in the longitudinal test position.

Water levels and artesian pressures in the Chad Basin of northeastern Nigeria, 1963-68

USGS Publications Warehouse

Carmalt, S.W.; Tibbitts, G.C.

1969-01-01

This report presents records of water levels and artesian pressures collected during 1963-68 on an observational network of 116 dug wells and boreholes (drilled wells) in the Chad Basin of northeastern Nigeria. The Chad Basin is underlain by the Chad Formation, a series of fluvio-lacustrine sediments which attain a thickness of 1,500 feet or more in Nigeria. Three water-bearing zones, designated Upper, Middle and Lower, have been identified in the Chad Formation of Nigeria. The Upper Zone aquifer, which contains water under both unconfined and confined conditions, provides the principal source of water to dug wells for domestic and village water supply. The Middle Zone aquifer is tapped by numerous deep boreholes (drilled wells) which provide water by artesian flow in more than 13,000 square miles of Nigeria north and east of Maiduguri. The Lower Zone, which is also confined has only been identified thus far (1969) in the vicinity of Maiduguri.

High-Resolution P'P' Precursor Imaging of Nazca-South America Plate Boundary Zones and Inferences for Transition Zone Temperature and Composition

NASA Astrophysics Data System (ADS)

Gu, Y. J.; Schultz, R.

2013-12-01

Knowledge of upper mantle transition zone stratification and composition is highly dependent on our ability to efficiently extract and properly interpret small seismic arrivals. A promising high-frequency seismic phase group particularly suitable for a global analysis is P'P' precursors, which are capable of resolving mantle structures at vertical and lateral resolution of approximately 5 and 200 km, respectively, owing to their shallow incidence angle and small, quasi-symmetric Fresnel zones. This study presents a simultaneous analysis of SS and P'P' precursors based on deconvolution, Radon transform and depth migration. Our multi-resolution survey of the mantle near Nazca-South America subduction zone reveals both olivine and garnet related transitions at depth below 400 km. We attribute a depressed 660 to thermal variations, whereas compositional variations atop the upper-mantle transition zone are needed to explain the diminished or highly complex reflected/scattered signals from the 410 km discontinuity. We also observe prominent P'P' reflections within the transition zone, especially near the plate boundary zone where anomalously high reflection amplitudes result from a sharp (~10 km thick) mineral phase change resonant with the dominant frequency of the P'P' precursors. Near the base of the upper mantle, the migration of SS precursors shows no evidence of split reflections near the 660-km discontinuity, but potential majorite-ilmenite (590-640 km) and ilmenite-perovskite transitions (740-750 km) are identified based on similarly processed high-frequency P'P' precursors. At nominal mantle temperatures these two phase changes may be seismically indistinguishable, but colder mantle conditions from the descending Nazca plate, the presence of water and variable Fe contents may cause sufficient separation for a reliable analysis. In addition, our preliminary results provide compelling evidence for multiple shallow lower-mantle reflections (at ~800 km) along the elongated plate boundary zones of South America. Slab stagnation at the base of the transition zone could play a key role, though a proper interpretation of this finding would likely entail compositional (rather than strictly thermal) variations in the vicinity of the descending oceanic crust and lithosphere. Overall, the resolution and sensitivity differences between low/intermediate- S and high-frequency P wave reflections are key considerations toward reconciling seismic and mineralogical models of transition zone structure, both at the study location and worldwide.

Interpretation of core and well log physical property data from drill hole UPH-3, Stephenson County, Illinois

USGS Publications Warehouse

Daniels, J.J.; Olhoeft, G.R.; Scott, J.H.

1984-01-01

Laboratory and well log physical property measurements show variations in the mineralogy with depth in UPH-3. Gamma ray values generally decrease with depth in the drill hole, corresponding to a decrease in the felsic mineral components of the granite. Correspondingly, an increase with depth in mafic minerals in the granite is indicated by the magnetic susceptibility, and gamma ray measurements. These mineralogic changes indicated by the geophysical well logs support the hypothesis of fractionation during continuous crystallization of the intrusive penetrated by UPH-3. Two fracture zones, and an altered zone within the granite penetrated by drill hole UPH-3 are defined by the physical property measurements. An abnormally low magnetic susceptibility response in the upper portion of the drill hole can be attributed to alteration of the rock adjacent to the sediments overlying the granite. Fracture zones can be identified from the sonic velocity, neutron, and resistivity measurements. A fracture zone, characterized by low resistivity values and low neutron values, is present in the depth interval from 1150 to 1320 m. Low magnetic susceptibility and high gamma ray values indicate the presence of felsic-micaceous pegmatites within this fracture zone. An unfractured region present from a depth of 1380 m to the bottom of the hole is characterized by an absence of physical property variations. The magnetic susceptibility and gamma ray measurements indicate a change in the amount of mafic minerals at the base of this otherwise homogenous region of the drilled interval. Abrupt changes and repeated patterns of physical properties within the drill hole may represent interruptions in the crystallization process of the melt or they may be indicative of critical temperatures for specific mineral assemblages within the intrusive.

From a long-lived upper-crustal magma chamber to rapid porphyry copper emplacement: Reading the geochemistry of zircon crystals at Bajo de la Alumbrera (NW Argentina)

NASA Astrophysics Data System (ADS)

Buret, Yannick; von Quadt, Albrecht; Heinrich, Christoph; Selby, David; Wälle, Markus; Peytcheva, Irena

2016-09-01

The formation of world class porphyry copper deposits reflect magmatic processes that take place in a deeper and much larger underlying magmatic system, which provides the source of porphyry magmas, as well as metal and sulphur-charged mineralising fluids. Reading the geochemical record of this large magmatic source region, as well as constraining the time-scales for creating a much smaller porphyry copper deposit, are critical in order to fully understand and quantify the processes that lead to metal concentration within these valuable mineral deposits. This study focuses on the Bajo de la Alumbrera porphyry copper deposit in Northwest Argentina. The deposit is centred on a dacitic porphyry intrusive stock that was mineralised by several pulses of porphyry magma emplacement and hydrothermal fluid injections. To constrain the duration of ore formation, we dated zircons from four porphyry intrusions, including pre-, syn- and post-mineralisation porphyries based on intersection relations between successive intrusion and vein generations, using high precision CA-ID-TIMS. Based on the youngest assemblages of zircon grains, which overlap within analytical error, all four intrusions were emplaced within 29 ka, which places an upper limit on the total duration of hydrothermal mineralisation. Re/Os dating of hydrothermal molybdenite fully overlaps with this high-precision age bracket. However, all four porphyries contain zircon antecrysts which record protracted zircon crystallisation during the ∼200 ka preceding the emplacement of the porphyries. Zircon trace element variations, Ti-in-zircon temperatures, and Hf isotopic compositions indicate that the four porphyry magmas record a common geochemical and thermal history, and that the four intrusions were derived from the same upper-crustal magma chamber. Trace element zoning within single zircon crystals confirms a fractional crystallisation trend dominated by titanite and apatite crystallisation. However, zircon cathodoluminescence imaging reveals the presence of intermediate low luminescent (dark) growth zones in many crystals from all intrusions, characterised by anomalously high Th, U and REE concentrations and transient excursions in trace element ratios. A return to the same fractionation trend after this excursion excludes external compositional forcing such as magma mixing. Instead we interpret the ;dark-zones; to record zircon crystallisation during a transient event of rapid growth that resulted from mafic magma injection into the base of the magma chamber, releasing a CO2-rich vapour phase into the dacitic crystal mush. We propose that this vapour phase then migrated upwards to the apical part of the magma chamber from where it was expelled, together with successive batches of magma, to form the porphyry copper deposit within a short time-span of less than a few 10,000 years. The short duration of host rock emplacement, hydrothermal alteration and mineralisation presented in this study provides critical constraints on fluid storage in magma chambers and the genesis of large porphyry copper deposits.

Seismic Regionalization of Michoacan, Mexico and Recurrence Periods for Earthquakes

NASA Astrophysics Data System (ADS)

Magaña García, N.; Figueroa-Soto, Á.; Garduño-Monroy, V. H.; Zúñiga, R.

2017-12-01

Michoacán is one of the states with the highest occurrence of earthquakes in Mexico and it is a limit of convergence triggered by the subduction of Cocos plate over the North American plate, located in the zone of the Pacific Ocean of our country, in addition to the existence of active faults inside of the state like the Morelia-Acambay Fault System (MAFS).It is important to make a combination of seismic, paleosismological and geological studies to have good planning and development of urban complexes to mitigate disasters if destructive earthquakes appear. With statistical seismology it is possible to characterize the degree of seismic activity as well as to estimate the recurrence periods for earthquakes. For this work, seismicity catalog of Michoacán was compiled and homogenized in time and magnitude. This information was obtained from world and national agencies (SSN, CMT, etc), some data published by Mendoza and Martínez-López (2016) and starting from the seismic catalog homogenized by F. R. Zúñiga (Personal communication). From the analysis of the different focal mechanisms reported in the literature and geological studies, the seismic regionalization of the state of Michoacán complemented the one presented by Vázquez-Rosas (2012) and the recurrence periods for earthquakes within the four different seismotectonic regions. In addition, stable periods were determined for the b value of the Gutenberg-Richter (1944) using the Maximum Curvature and EMR (Entire Magnitude Range Method, 2005) techniques, which allowed us to determine recurrence periods: years for earthquakes upper to 7.5 for the subduction zone (A zone) with EMR technique and years with MAXC technique for the same years for earthquakes upper to 5 for B1 zone with EMR technique and years with MAXC technique; years for earthquakes upper to 7.0 for B2 zone with EMR technique and years with MAXC technique; and the last one, the Morelia-Acambay Fault Sistem zone (C zone) years for earthquakes upper to 5 with EMR technique and years with MAXC technique. This recurrence periods are very similar to periods calculated by Garduño-Monroy (2009) and Sunye-Puchol (2015) using paleoseismological methods. If we consider that the MAFS cross Zacapu, Pátzcuaro, Morelia, Cuitzeo, Maravatío and Acambay, the affected population would be around 1132807 habitants.

Review of metamorphic and kinematic data from Internal Crystalline Massifs (Western Alps): PTt paths and exhumation history

NASA Astrophysics Data System (ADS)

Gasco, Ivano; Gattiglio, Marco; Borghi, Alessandro

2013-01-01

Detailed geological mapping combined with micro-structural and petrological investigation allowed to clarify the tectono-metamorphic relationships between continental and oceanic units transition in the Penninic domain of the Western Alps. The three study areas (Gressoney, Orco and Susa sections) take into consideration the same structural level across the axial metamorphic belt of the Western Italian Alps, i.e., a geological section across the Internal Crystalline Massifs vs Piedmont Zone boundary. The units outcropping in these areas can be grouped into two Tectonic Elements according to their tectono-metamorphic evolution. The Lower Tectonic Element (LTE) consists of the Internal Crystalline Massifs and the Lower Piedmont Zone (Zermatt-Saas like units), both showing well preserved eclogite facies relics. Instead, the Upper Tectonic Element (UTE) consists of the Upper Piedmont Zone (Combin like units) lacking evidence of eclogite facies relics. In the Lower Tectonic Element two main Alpine tectono-metamorphic stages were identified: M1/D1 developed under eclogite facies conditions and M2/D2 is related to the development of the regional foliation under greenschist to epidote-albite amphibolite facies conditions. In the Upper Tectonic Element the metamorphic stage M1/D1 developed under bluschist to greenschist facies conditions and M2/D2 stage under greenschist facies conditions. These two Tectonic Elements are separated by a tectonic contact of regional importance generally developed along the boundary between the Lower and the Upper Piedmont zone under greenschist facies conditions. PT data compared to geochronology indicate that the first exhumation of ICM can be explained by buoyancy forces acting along the subduction channel that occurred during the tectonic coupling between the continental and oceanic eclogite units. These buoyancy forces vanished at the base of the crust where the density difference between the subducted crustal units and the surroundings rocks is too low. A stage where compression prevails on the previous exhumation followed, which leads to the development of the regional foliation under greenschist to amphibolite facies metamorphic conditions. Further exhumation occurred after the M2/D2 stage at shallower crustal levels along conjugated shear zones leading to the development of a composite axial dome consisting of eclogite-bearing continental-oceanic units (ICM and Zermatt-Saas Zones) beneath greenschist ones (Combin Zone).

Earthquake nucleation on faults with rate-and state-dependent strength

USGS Publications Warehouse

Dieterich, J.H.

1992-01-01

Dieterich, J.H., 1992. Earthquake nucleation on faults with rate- and state-dependent strength. In: T. Mikumo, K. Aki, M. Ohnaka, L.J. Ruff and P.K.P. Spudich (Editors), Earthquake Source Physics and Earthquake Precursors. Tectonophysics, 211: 115-134. Faults with rate- and state-dependent constitutive properties reproduce a range of observed fault slip phenomena including spontaneous nucleation of slip instabilities at stresses above some critical stress level and recovery of strength following slip instability. Calculations with a plane-strain fault model with spatially varying properties demonstrate that accelerating slip precedes instability and becomes localized to a fault patch. The dimensions of the fault patch follow scaling relations for the minimum critical length for unstable fault slip. The critical length is a function of normal stress, loading conditions and constitutive parameters which include Dc, the characteristic slip distance. If slip starts on a patch that exceeds the critical size, the length of the rapidly accelerating zone tends to shrink to the characteristic size as the time of instability approaches. Solutions have been obtained for a uniform, fixed-patch model that are in good agreement with results from the plane-strain model. Over a wide range of conditions, above the steady-state stress, the logarithm of the time to instability linearly decreases as the initial stress increases. Because nucleation patch length and premonitory displacement are proportional to Dc, the moment of premonitory slip scales by D3c. The scaling of Dc is currently an open question. Unless Dc for earthquake faults is significantly greater than that observed on laboratory faults, premonitory strain arising from the nucleation process for earthquakes may by too small to detect using current observation methods. Excluding the possibility that Dc in the nucleation zone controls the magnitude of the subsequent earthquake, then the source dimensions of the smallest earthquakes in a region provide an upper limit for the size of the nucleation patch. ?? 1992.

Direct push injection logging for high resolution characterization of low permeability zones

NASA Astrophysics Data System (ADS)

Liu, G.; Knobbe, S.; Butler, J. J., Jr.; Reboulet, E. C.; Borden, R. C.; Bohling, G.

2017-12-01

One of the grand challenges for groundwater protection and contaminated site remediation efforts is dealing with the slow, yet persistent, release of contaminants from low permeability zones. In zones of higher permeability, groundwater flow is relatively fast and contaminant transport can be more effectively affected by treatment activities. In the low permeability zones, however, groundwater flow and contaminant transport are slow and thus become largely insensitive to many in-situ treatment efforts. Clearly, for sites with low permeability zones, accurate depiction of the mass exchange between the low and higher permeability zones is critical for designing successful groundwater protection and remediation systems, which requires certain information such as the hydraulic conductivity (K) and porosity of the subsurface. The current generation of field methods is primarily developed for relatively permeable zones, and little work has been undertaken for characterizing zones of low permeability. For example, the direct push injection logging (DPIL) approach (e.g., Hydraulic Profiling Tool by Geoprobe) is commonly used for high resolution estimation of K over a range of 0.03 to 23 m/d. When K is below 0.03 m/d, the pressure responses from the current DPIL are generally too high for both the formation (potential formation alteration at high pressure) and measuring device (pressure exceeding the upper sensor limit). In this work, we modified the current DPIL tool by adding a low-flow pump and flowmeter so that injection logging can be performed with much reduced flow rates when K is low. Numerical simulations showed that the reduction in injection rates (reduced from 250 to 1 mL/min) allowed pressures to be measurable even when K was as low as 0.001 m/d. They also indicated that as the K decreased, the pore water pressure increase induced by probe advancement had a more significant impact on DPIL results. A new field DPIL profiling procedure was developed for reducing that impact. Our preliminary test results in both the lab and at a field site have demonstrated the promise of the modified DPIL approach as a practical method for characterizing low permeability zones.

The role of soil processes in determining mechanisms of slope failure and hillslope development in a humid-tropical forest eastern Puerto Rico

USGS Publications Warehouse

Simon, A.; Larsen, M.C.; Hupp, C.R.

1990-01-01

Translational failures, with associated downslope earthflow components and shallow slides, appear to be the primary mechanism of hillslope denudation in the humid tropical forests of the mountains of eastern Puerto Rico. In-situ weathering of quartz diorite and marine-deposited volcaniclastics produces residual soil (saprolite; up to 21 m deep) / weathered rock profiles. Discontinuous zones of contrasting density and permeability particularly in quartz-diorite slopes at 0.5 m, and between 3 and 7 m, create both pathways and impedances for water that can result in excess pore pressures and, ultimately, aid in determining the location of failure planes and magnitudes of slope failures. In combination with relict fractures which create planes of weakness within the saprolite, and the potential significance of tensile stresses in the upper zone of saprolite (hypothesized to be caused by subsurface soil creep), shear failure can then occur during or after periods of heavy rainfall. Results of in-situ shear-strength testing show negative y-intercepts on the derived Mohr-Coulomb failure envelopes (approximately 50% of all tests) that are interpreted as apparent tensile stresses. Observation of tension cracks 1-2 m deep support the test data. Subsurface soil creep can cause extension of the soil and the development of tensile stresses along upper-slope segments. Shear-strength data support this hypothesis for both geologic types. Apparent values of maximum and mean tensile stress are greatest along upper slopes (16.5 and 6.29 kPa). Previously documented maximum rates of downslope movement coincided with local minima of shear strength, and the shear-strength minimum for all tests was located near 0.5 m below land surface, the shallow zone of contrasting permeabilities. These results indicate that subsurface soil creep, a slow semi-continuous process, may exert a profound influence on rapid, shallow slope failures in saprolitic soils. Data indicate that cove slopes in quartz diorite tend to be the most unstable when saturation levels reach 75%. Deep failures (7 m deep) appear the most critical but not the most frequent because pore pressure build-up will occur more rapidly in the upper perched zone of translocated clays before reaching the lower zone between 3 and 7 m. Frequent shallow failures could reduce the probability of deeper failures by removing overburden and reducing shear stress at depth. Deep failures are more likely to result from storm events of great duration and intensity. Sixty-six 'naturally occurring' and more than 100 'road-related' landslides were mapped. Forest elevations exceed 1000 m, but the majority of these failures were found between 600 and 800 m in elevation. This appears to be the area where there is sufficient concentration of subsurface water to result in excess pore pressures. The high percentage of slope failures in the 600-800-m range, relative to the percentage at higher elevations, suggests that differences in soil-water processes are responsible for the form of these mountain slopes. Steep linear segments are maintained at higher elevations. Slope angles are reduced in the 600-800-m range by frequent shallow slides, creating a largely concave surface. In combination, slope segments above 800 m, and those between 600 and 800 m, produce the characteristic form of the mountains of eastern Puerto Rico. ?? 1990.

Taxonomic and compositional differences of ground-dwelling arthropods in riparian habitats in Glen Canyon, Arizona, USA

USGS Publications Warehouse

Ralston, Barbara; Cobb, Neil S.; Brantley, Sandra L.; Higgins, Jacob; Yackulic, Charles B.

2017-01-01

The disturbance history, plant species composition, productivity, and structural complexity of a site can exert bottom-up controls on arthropod diversity, abundance, and trophic structure. Regulation alters the hydrology and disturbance regimes of rivers and affects riparian habitats by changing plant quality parameters. Fifty years of regulation along the Colorado River downstream of Glen Canyon Dam has created a no-analog, postdam “lower” riparian zone close to the water's edge that includes tamarisk (Tamarix sp.), a nonnative riparian shrub. At the same time, the predam “upper” facultative riparian zone has persisted several meters above the current flood stage. In summer 2009, we used pitfall traps within these 2 riparian zones that differ in plant composition, productivity, and disturbance frequency to test for differences in arthropod community (Hymenoptera, Arachnida, and Coleoptera) structure. Arthropod community structure differed substantially between the 2 zones. Arthropod abundance and species richness was highest in the predam upper riparian zone, even though there was a greater amount of standing plant biomass in the postdam lower riparian zone. Omnivore abundance was proportionately greater in the upper riparian zone and was associated with lower estimated productivity values. Predators and detritivores were proportionately greater in the postdam lower riparian zone. In this case, river regulation may create habitats that support species of spiders and carabid beetles, but few other species that are exclusive to this zone. The combined richness found in both zones suggests a small increase in total richness and functional diversity for the Glen Canyon reach of the Colorado River.

Evidence of Convective Redistribution of Carbon Monoxide in Aura Tropospheric Emission Sounder (TES) and Microwave Limb Sounder (MLS) Observations

NASA Technical Reports Server (NTRS)

Manyin, Michael; Douglass, Anne; Schoeberl, Mark

2010-01-01

Vertical convective transport is a key element of the tropospheric circulation. Convection lofts air from the boundary layer into the free troposphere, allowing surface emissions to travel much further, and altering the rate of chemical processes such as ozone production. This study uses satellite observations to focus on the convective transport of CO from the boundary layer to the mid and upper troposphere. Our hypothesis is that strong convection associated with high rain rate regions leads to a correlation between mid level and upper level CO amounts. We first test this hypothesis using the Global Modeling Initiative (GMI) chemistry and transport model. We find the correlation is robust and increases as the precipitation rate (the strength of convection) increases. We next examine three years of CO profiles from the Tropospheric Emission Sounder (TES) and Microwave Limb Sounder (MLS) instruments aboard EOS Aura. Rain rates are taken from the Tropical Rainfall Measuring Mission (TRMM) 3B-42 multi-satellite product. Again we find a correlation between mid-level and upper tropospheric CO, which increases with rain rate. Our result shows the critical importance of tropical convection in coupling vertical levels of the troposphere in the transport of trace gases. The effect is seen most clearly in strong convective regions such as the Inter-tropical Convergence Zone.

AmeriFlux US-CZ4 Sierra Critical Zone, Sierra Transect, Subalpine Forest, Shorthair

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

Goulden, Michael

This is the AmeriFlux version of the carbon flux data for the site US-CZ4 Sierra Critical Zone, Sierra Transect, Subalpine Forest, Shorthair. Site Description - Half hourly data are available at https://www.ess.uci.edu/~california/. This site is one of four Southern Sierra Critical Zone Observatory flux towers operated along an elevation gradient (sites are USCZ1, USCZ2, USCZ3 and USCZ4). This site is a lodgepole pine subalpine woodland with no recent disturbance.

Geohydrology and potential for upward movement of saline water in the Cocoa well field, East Orange County, Florida

USGS Publications Warehouse

Phelps, G.G.; Schiffer, D.M.

1996-01-01

The Floridan aquifer system, an approximately 2,000-foot thick sequence of Eocene-age limestone and dolomite, is the main source of water supply in central Florida. Hydraulic conductivity is different in strata of different lithology and is the basis for separating the aquifer system into the Upper Floridan aquifer, a middle semi- confining unit, and the Lower Floridan aquifer. The coastal city of Cocoa withdraws about 26 million gallons of water per day from the Upper Floridan aquifer from a well field in east Orange County, about 25 miles inland. About 60 million gallons per day are withdrawn from the Upper Floridan aquifer and 56 million gallons per day from the Lower Floridan aquifer in the Orlando area, about 15 miles west of the Cocoa well field. Wells drilled in the Cocoa well field from 1955-61 yielded water with chloride concentrations ranging from 25-55 milligrams per liter. Soon after the wells were put in service, chloride concentrations increased; therefore, new wells were drilled further inland. Chloride concen- trations in water from many of the new wells also have increased. Possible sources of saline water are lateral movement of relict seawater in the Upper Floridan aquifer from the east, regional upconing of saline water from the Lower Floridan aquifer or underlying older rocks, or localized upward movement of saline water through fractures. Several test wells were drilled to provide information about chloride concentration changes with depth and to monitor changes with time, including a multi-zone well drilled in 1965 (well C) and two wells drilled in the 1990's (wells R and S). Chloride concentrations have increased in the zone pumped by the supply wells (the upper 500 feet of the aquifer) and in the 1,351-1,357-foot deep zone of well C, but not in the two intervening zones. This indicates that the source of saline water is located laterally, rather than vertically, from the pumped zone in the area of well C. The potential for upward movement of saline water depends on the direction of the vertical hydraulic gradient and on the vertical hydraulic conductivity of the aquifer. A series of aquifer tests was run in 1993-94 and existing water-level and water-quality data were analyzed to evaluate the potential for upward movement of saline water in the well field. The transmissivity of the upper 500 feet of the aquifer is about 100,000 feet squared per day (the horizontal hydraulic conductivity is about 200 feet per day) and the storage coefficient is about 2x10 -4. Horizontal hydraulic conductivities determined from slug tests of the three deepest zones of well C ranged from 20-50 feet per day. Vertical hydraulic conductivities probably do not exceed 0.05 feet per day. The vertical hydraulic gradient is determined by comparing water levels in the various zones, but because of density differences, unadjusted water levels in the deepest zone investigated cannot be directly compared to water levels in the overlying freshwater zones. The difference between environmental-water heads (adjusted for density differences) in the saline-water zone of well C and the overlying freshwater zone were calculated from measured water levels for the period 1966 to 1994. During most of this time period, the gradient was downward, indicating that saline water did not move upward. Upconing of saline water probably is not taking place in the center and western part of the well field, based on the low vertical hydraulic conductivity values estimated for the middle semi-confining unit, the generally downward vertical hydraulic gradient, and the constant chloride concentrations in the intermediate zones of well C. However, there is no information about the extent of the zone of low vertical hydraulic conductivity gradient in the eastern part of the well field. Thus, increased chloride concentrations in supply wells in the eastern part of the well field could be caused either by lateral movement of saline water from the east, or by upwar

Simulation of ground-water flow and stream-aquifer relations in the vicinity of the Savannah River Site, Georgia and South Carolina, predevelopment through 1992

USGS Publications Warehouse

Clarke, John S.; West, Christopher T.

1998-01-01

Ground-water flow and stream-aquifer relations were simulated for seven aquifers in Coastal Plain sediments in the vicinity of the U.S. Department of Energy, Savannah River Site (SRS), in Georgia and South Carolina to evaluate the potential for ground water containing hazardous materials to migrate from the SRS into Georgia through aquifers underlying the Savannah River (trans-river flow). The work was completed as part of a cooperative study between the U.S. Geological Survey, the U.S. Department of Energy, and Georgia Department of Natural Resources. The U.S. Geological Survey three-dimensional finite-difference ground-water flow model, MODFLOW, was used to simulate ground-water flow in three aquifer systems containing seven discrete aquifers: (1) the Floridan aquifer system, consisting of the Upper Three Runs and Gordon aquifers in sediments of Eocene age; (2) the Dublin aquifer system, consisting of the Millers Pond, and upper and lower Dublin aquifers in sediments of Paleocene and Late Cretaceous age; and (3) the Midville aquifer system, consisting of the upper and lower Midville aquifers of sediments in Late Cretaceous age. Ground-water flow was simulated using a series of steady-state simulations of predevelopment (pre-1953) conditions and six pumping periods--1953-60, 1961-70, 1971-75, 1976-80, 1981-86, and 1987-92--results are presented for predevelopment (prior to 1953) and modern-day (1987-92) conditions. Total simulated predevelopment inflow is 1,023 million gallons per day (Mgal/d), of which 76 percent is contributed by leakage from the Upper Three Runs aquifer. Over most of the study area, pumpage induced changes in ground-water levels, ground-water discharge to streams, and water-budget components were small during 1953-92, and changes in aquifer storage were insignificant. Simulated drawdown between predevelopment and modern-day conditions is small (less than 7 feet) and of limited areal extent--the largest simulated declines occur in the upper and lower Dublin aquifers in the vicinity of the Sandoz plant site in South Carolina. These declines extend beneath the Savannah River and change the configuration of the simulated potentiometric surface and flow paths near the river. Predevelopment and modern-day flowpaths were simulated near the Savannah River by using the U.S. Geological Survey particle-tracking code MODPATH. Eastward and westward zones of trans-river flow were identified in three principal areas as follows: --zone 1-from the Fall Line southward to the confluence of Hollow Creek and the Savannah River; --zone 2-from the zone 1 boundary southward to the southern border of the SRS (not including the Lower Three Runs Creek section); and --zone 3-from the zone 2 boundary, southward into the northern part of Screven County, Ga. All zones for all model layers were located within or immediately adjacent to the Savannah River alluvial valley and most were located in the immediate vicinity of the Savannah River. Recharge areas for each of the zones of trans-river flow generally are in the vicinity of major interstream drainage divides. Mean time-of-travel simulated for predevelopment conditions ranges from 300 to 24,000 years for westward trans-river flow zones; and from 550 to 41,000 years for eastward zones. Corresponding travel times under modern-day conditions range from 300 to 34,000 years for westward zones and from 580 to 31,000 years for eastward zones. Differences in travel times between predevelopment and modern-day simulations result from changes in hydraulic gradients due to ground-water pumpage that alter flow paths in the vicinity of the river. Recharge to Georgia trans-river flow zones originating on the SRS was simulated for the Gordon and upper Dublin aquifers during predevelopment, and in the Gordon aquifer during 1987-92. During 1987-92, SRS recharge was simulated in 6 model cells covering a 2-square mile area, located away from areas of ground-water contamination. Si

Electrical resistivity and porosity structure of the upper Biscayne Aquifer in Miami-Dade County, Florida

NASA Astrophysics Data System (ADS)

Whitman, Dean; Yeboah-Forson, Albert

2015-12-01

Square array electrical soundings were made at 13 sites in the Biscayne Aquifer distributed between 1 and 20 km from the shoreline. These soundings were modeled to investigate how resistivity varies spatially and with depth in the upper 15 m of the aquifer. Porosity was estimated from the modeled formation resistivity and observed pore fluid resistivity with Archie's Law. The models were used to interpolate resistivity and porosity surfaces at -2, -5, -8, and -15 m elevations. Modeled resistivity in the unsaturated zone is generally higher than 300 Ω m with the resistivity at sites with thick unsaturated zones greater than 1000 Ω m. Resistivity in the saturated zone ranges from 30 to 320 Ω m. At many sites in the western portions of the study area, resistivity is constant or increases with depth whereas sites in the center of the Atlantic Coastal Ridge exhibit a distinct low resistivity zone (ρ < 45 Ω m) at elevations ranging between -5 and -10 m. At one site near the shore of Biscayne Bay, the resistivity is less than 10 Ω m at -5 m elevation reflecting the presence of salt water in the aquifer. The estimated porosity ranges between 14% and 71% with modal values near 25%. The porosity structure varies both with depth and spatially. Western sites exhibit a high porosity zone at shallow depths best expressed in a NE-SW trending zone of 40-50% porosity situated near the western margin of the Atlantic Coastal Ridge. This zone roughly corresponds in depth with the Q5 chronostratigraphic unit of the Miami Fm. which constitutes the upper flow unit of the Biscayne Aquifer. The highest porosity (>50%) is seen at elevations below -5 m at sites in the center of the Atlantic Coastal Ridge and likely corresponds to solution features. The general NE-SW trend of the resistivity and porosity structure suggests a causal connection with the Pleistocene paleogeography and sedimentary environments.

Insights into the base of the critical zone from geophysical logging and groundwater flow testing at U.S. Critical Zone Observatories (CZO) and critical zone study sites (CZs)

NASA Astrophysics Data System (ADS)

Carr, B.; Zhang, Y.; Ren, S.; Flinchum, B. A.; Parsekian, A.; Holbrook, S.; Riebe, C. S.; Moravec, B. G.; Chorover, J.; Pelletier, J. D.; Richter, D. D., Jr.

2017-12-01

Four prominent hypotheses exist and predict conceptual models defining the base of the critical zone. These hypotheses lack insights and constraints from borehole data since few deep (> 20 m) boreholes (and even fewer connected wellfields) are present in the U.S. Critical Zone Observatories (CZO) and similar critical zone study sites (CZs). The influence and interaction of fracture presence, fracture density, fracture orientation, groundwater presence and groundwater flow have only begun to be analyzed relative to any definition of the base of the critical zone. In this presentation, we examine each hypothesis by jointly evaluating borehole geophysical logs and groundwater testing datasets collected by the Wyoming Center for Environmental Hydrology and Geophysics (WyCEHG) since 2014 at these deep CZO or CZ boreholes. Deep boreholes allow a unique opportunity to observe the factors influencing groundwater transmissivity/storage capacity within the three main subsurface CZ layers: Unconsolidated (soil/saprolite), Fractured/weathered Bedrock, and Protolith bedrock (i.e. less fractured bedrock). The boreholes used in this study consist of: 1) nine wells of the Blair-Wallis (WY) WyCEHG CZ, 2) two wells in Catalina-Jemez CZO (Valle Caldera NM) and 3) one borehole at the Calhoun (SC) CZO. At this time, these are the only sites that contain boreholes with depths ranging from at least 20 m up to 70m that have been geophysically logged with full-waveform seismic, acoustic and optical televiewer, electric, electromagnetic, flowmeter (impeller and heat pulse), fluid temperature, fluid conductivity and nuclear magnetic resonance. Further, the Blair-Wallis CZ site contains five hydraulically connected wells that allow us to estimate formation transmissivity and storage coefficients at increasing scales by conducting: slug tests, FLUTe™ borehole profiling, and cross-hole pumping tests. These well tests provide direct hydraulic data of the bedrock (both fractured and protolith) that can be integrated with geophysical logging data. Because fracture permeability is the dominant mechanism for groundwater transport in these igneous environments, a joint analysis of geophysical logging and hydraulic testing data provides in situ material-property-based refinements for the defining the base of the critical zone.

Seismic tomography shows that upwelling beneath Iceland is confined to the upper mantle

USGS Publications Warehouse

Foulger, G.R.; Pritchard, M.J.; Julian, B.R.; Evans, J.R.; Allen, R.M.; Nolet, G.; Morgan, W.J.; Bergsson, B.H.; Erlendsson, P.; Jakobsdottir, S.; Ragnarsson, S.; Stefansson, R.; Vogfjord, K.

2001-01-01

We report the results of the highest-resolution teleseismic tomography study yet performed of the upper mantle beneath Iceland. The experiment used data gathered by the Iceland Hotspot Project, which operated a 35-station network of continuously recording, digital, broad-band seismometers over all of Iceland 1996-1998. The structure of the upper mantle was determined using the ACH damped least-squares method and involved 42 stations, 3159 P-wave, and 1338 S-wave arrival times, including the phases P, pP, sP, PP, SP, PcP, PKIKP, pPKIKP, S, sS, SS, SKS and Sdiff. Artefacts, both perceptual and parametric, were minimized by well-tested smoothing techniques involving layer thinning and offset-and-averaging. Resolution is good beneath most of Iceland from ??? 60 km depth to a maximum of ??? 450 km depth and beneath the Tjornes Fracture Zone and near-shore parts of the Reykjanes ridge. The results reveal a coherent, negative wave-speed anomaly with a diameter of 200-250 km and anomalies in P-wave speed, Vp, as strong as -2.7 per cent and in S-wave speed, Vs, as strong as -4.9 per cent. The anomaly extends from the surface to the limit of good resolution at ??? 450 km depth. In the upper ??? 250 km it is centred beneath the eastern part of the Middle Volcanic Zone, coincident with the centre of the ??? 100 mGal Bouguer gravity low over Iceland, and a lower crustal low-velocity zone identified by receiver functions. This is probably the true centre of the Iceland hotspot. In the upper ??? 200 km, the low-wave-speed body extends along the Reykjanes ridge but is sharply truncated beneath the Tjornes Fracture Zone. This suggests that material may flow unimpeded along the Reykjanes ridge from beneath Iceland but is blocked beneath the Tjornes Fracture Zone. The magnitudes of the Vp, Vs and Vp/Vs anomalies cannot be explained by elevated temperature alone, but favour a model of maximum temperature anomalies <200 K, along with up to ??? 2 per cent of partial melt in the depth range ??? 100-300 km beneath east-central Iceland. The anomalous body is approximately cylindrical in the top 250 km but tabular in shape at greater depth, elongated north-south and generally underlying the spreading plate boundary. Such a morphological change and its relationship to surface rift zones are predicted to occur in convective upwellings driven by basal heating, passive upwelling in response to plate separation and lateral temperature gradients. Although we cannot resolve structure deeper than ??? 450 km, and do not detect a bottom to the anomaly, these models suggest that it extends no deeper than the mantle transition zone. Such models thus suggest a shallow origin for the Iceland hotspot rather than a deep mantle plume, and imply that the hotspot has been located on the spreading ridge in the centre of the north Atlantic for its entire history, and is not fixed relative to other Atlantic hotspots. The results are consistent with recent, regional full-thickness mantle tomography and whole-mantle tomography images that show a strong, low-wave-speed anomaly beneath the Iceland region that is confined to the upper mantle and thus do not require a plume in the lower mantle. Seismic and geochemical observations that are interpreted as indicating a lower mantle, or core-mantle boundary origin for the North Atlantic Igneous Province and the Iceland hotspot should be re-examined to consider whether they are consistent with upper mantle processes.

78 FR 45871 - National Oil and Hazardous Substances Pollution Contingency Plan; National Priorities List...

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Microstructural and fabric characterization of brittle-ductile transitional deformation of middle crustal rocks along the Jinzhou detachment fault zone, Northeast China

NASA Astrophysics Data System (ADS)

Zhang, Juyi; Jiang, Hao; Liu, Junlai

2017-04-01

Detachment fault zones (DFZs) of metamorphic core complexes generally root into the middle crust. Exhumed DFZs therefore generally demonstrate structural, microstructural and fabric features characteristic of middle to upper crustal deformation. The Jinzhou detachment fault zone from the Liaonan metamorphic core complex is characterized by the occurrence of a sequence of fault rocks due to progressive shearing along the fault zone during exhumation of the lower plate. From the exhumed fabric zonation, cataclastic rocks formed in the upper crust occur near the Jinzhou master detachment fault, and toward the lower plate gradually changed to mylonites, mylonitic gneisses and migmatitic gneisses. Correspondingly, these fault rocks have various structural, microstructural and fabric characteristics that were formed by different deformation and recrystallization mechanisms from middle to upper crustal levels. At the meanwhile, various structural styles for strain localization were formed in the DFZ. As strain localization occurs, rapid changes in deformation mechanisms are attributed to increases in strain rates or involvement of fluid phases during the brittle-ductile shearing. Optical microscopic studies reveal that deformed quartz aggregates in the lower part of the detachment fault zone are characterized by generation of dynamically recrystallized grains via SGR and BLG recrystallization. Quartz rocks from the upper part of the DFZ have quartz porphyroclasts in a matrix of very fine recrystallized grains. The porphyroclasts have mantles of sub-grains and margins grain boundary bulges. Electron backscattered diffraction technique (EBSD) quartz c-axis fabric analysis suggests that quartz grain aggregates from different parts of the DFZ possess distinct fabric complexities. The c-axis fabrics of deformed quartz aggregates from mylonitic rocks in the lower part of the detachment fault zone preserve Y-maxima which are ascribed to intermediate temperature deformation (500-630˚ C), whereas complicated fabric patterns (e.g. asymmetric single girdles) are formed in fault rocks from the upper part of the DFZ. The increasing fabric complexity is here interpreted as the result of progressive superposition of fault rocks by shearing either at relatively shallow levels or high rate of strain, during exhumation of the lower plate and shear zone rocks. The above observations and interpretations imply that dislocation creep processes contribute to the dynamic recrystallization of quartz in the middle crustal brittle-ductile transition. Progressive shearing as a consequence of exhumation of the lower plate of the MCC contributed to the obvious structural, microstructural and fabric superpositions. Strain localization occurs as the progressive shearing proceeded. Transition of mechanisms of deformation and dynamic recrystallization during strain localization may be resulted from changes in temperature conditions, in strain rates or addition of minor amount water.

Imaging of upper crustal structure beneath East Java-Bali, Indonesia with ambient noise tomography

NASA Astrophysics Data System (ADS)

Martha, Agustya Adi; Cummins, Phil; Saygin, Erdinc; Sri Widiyantoro; Masturyono

2017-12-01

The complex geological structures in East Java and Bali provide important opportunities for natural resource exploitation, but also harbor perils associated with natural disasters. Such a condition makes the East Java region an important area for exploration of the subsurface seismic wave velocity structure, especially in its upper crust. We employed the ambient noise tomography method to image the upper crustal structure under this study area. We used seismic data recorded at 24 seismographs of BMKG spread over East Java and Bali. In addition, we installed 28 portable seismographs in East Java from April 2013 to January 2014 for 2-8 weeks, and we installed an additional 28 seismographs simultaneously throughout East Java from August 2015 to April 2016. We constructed inter-station Rayleigh wave Green's functions through cross-correlations of the vertical component of seismic noise recordings at 1500 pairs of stations. We used the Neighborhood Algorithm to construct depth profiles of shear wave velocity (Vs). The main result obtained from this study is the thickness of sediment cover. East Java's southern mountain zone is dominated by higher Vs, the Kendeng basin in the center is dominated by very low Vs, and the Rembang zone (to the North of Kendeng zone) is associated with medium Vs. The existence of structures with oil and gas potential in the Kendeng and Rembang zones can be identified by low Vs.

Designing a suite of measurements to understand the critical zone

NASA Astrophysics Data System (ADS)

Brantley, S. L.; DiBiase, R.; Russo, T.; Shi, Y.; Lin, H.; Davis, K. J.; Kaye, M.; Hill, L.; Kaye, J.; Neal, A. L.; Eissenstat, D.; Hoagland, B.; Dere, A. L.

2015-09-01

Many scientists have begun to refer to the earth surface environment from the upper canopy to the depths of bedrock as the critical zone (CZ). Identification of the CZ as a worthy object of study implicitly posits that the study of the whole earth surface will provide benefits that do not arise when studying the individual parts. To study the CZ, however, requires prioritizing among the measurements that can be made - and we do not generally agree on the priorities. Currently, the Susquehanna Shale Hills Critical Zone Observatory (SSHCZO) is expanding from a small original study area (0.08 km2, Shale Hills catchment), to a much larger watershed (164 km2, Shavers Creek watershed) and is grappling with the necessity of prioritization. This effort is an expansion from a monolithologic first-order forested catchment to a watershed that encompasses several lithologies (shale, sandstone, limestone) and land use types (forest, agriculture). The goal of the project remains the same: to understand water, energy, gas, solute and sediment (WEGSS) fluxes that are occurring today in the context of the record of those fluxes over geologic time as recorded in soil profiles, the sedimentary record, and landscape morphology. Given the small size of the original Shale Hills catchment, the original measurement design resulted in measurement of as many parameters as possible at high temporal and spatial density. In the larger Shavers Creek watershed, however, we must focus the measurements. We describe a strategy of data collection and modelling based on a geomorphological framework that builds on the hillslope as the basic unit. Interpolation and extrapolation beyond specific sites relies on geophysical surveying, remote sensing, geomorphic analysis, the study of natural integrators such as streams, ground waters or air, and application of a suite of CZ models. In essence, we are hypothesizing that pinpointed measurements of a few important variables at strategic locations will allow development of predictive models of CZ behavior. In turn, the measurements and models will reveal how the larger watershed will respond to perturbations both now and into the future.

Designing a suite of measurements to understand the critical zone

NASA Astrophysics Data System (ADS)

Brantley, Susan L.; DiBiase, Roman A.; Russo, Tess A.; Shi, Yuning; Lin, Henry; Davis, Kenneth J.; Kaye, Margot; Hill, Lillian; Kaye, Jason; Eissenstat, David M.; Hoagland, Beth; Dere, Ashlee L.; Neal, Andrew L.; Brubaker, Kristen M.; Arthur, Dan K.

2016-03-01

Many scientists have begun to refer to the earth surface environment from the upper canopy to the depths of bedrock as the critical zone (CZ). Identification of the CZ as an integral object worthy of study implicitly posits that the study of the whole earth surface will provide benefits that do not arise when studying the individual parts. To study the CZ, however, requires prioritizing among the measurements that can be made - and we do not generally agree on the priorities. Currently, the Susquehanna Shale Hills Critical Zone Observatory (SSHCZO) is expanding from a small original focus area (0.08 km2, Shale Hills catchment), to a larger watershed (164 km2, Shavers Creek watershed) and is grappling with the prioritization. This effort is an expansion from a monolithologic first-order forested catchment to a watershed that encompasses several lithologies (shale, sandstone, limestone) and land use types (forest, agriculture). The goal of the project remains the same: to understand water, energy, gas, solute, and sediment (WEGSS) fluxes that are occurring today in the context of the record of those fluxes over geologic time as recorded in soil profiles, the sedimentary record, and landscape morphology. Given the small size of the Shale Hills catchment, the original design incorporated measurement of as many parameters as possible at high temporal and spatial density. In the larger Shavers Creek watershed, however, we must focus the measurements. We describe a strategy of data collection and modeling based on a geomorphological and land use framework that builds on the hillslope as the basic unit. Interpolation and extrapolation beyond specific sites relies on geophysical surveying, remote sensing, geomorphic analysis, the study of natural integrators such as streams, groundwaters or air, and application of a suite of CZ models. We hypothesize that measurements of a few important variables at strategic locations within a geomorphological framework will allow development of predictive models of CZ behavior. In turn, the measurements and models will reveal how the larger watershed will respond to perturbations both now and into the future.

Preliminary study on the L ate Cretaceous ostracods from continental scientific drilling SK1 in the Songliao Basin, NE China

NASA Astrophysics Data System (ADS)

Xi, Dangpeng; Qu, Haiying; Shi, Zhongye; Wan, Xiaoqiao

2017-04-01

Songliao Basin is one of the biggest lacustrine systems in Asia during Cretaceous age. Widespread deposits in the basin are mainly composed of clastic sediments which contain abundant fossils including gastropod, bivalves, ostracods, vertebrates and others. These well preserved ostracod fossils provide us valuable information about past climate changes and biotic responses in a greenhouse environment.The Cretaceous Continental Scientific Drilling in the Songliao Basin (SK1) offers a rare opportunity to study Late Cretaceous non-marine ostracod. The SK1 was drilled separately in two boreholes: the lower 959.55-meter-thick south core (SK1(s)), and the upper 1636.72-meter-thick north core (SK1 (n)), containing the Upper Quantou, Qingshankou, Yaojia, Nenjiang Formation, Sifangtai, Mingshui and lower Taikang formations. Here we establish high-resolution non-marine ostracod biostratigraphy based on SK1. 80 species belonging to 12 genera in the SK1(S) and 45 species assigned to 20 genera in the SK1(n) have been recovered. Nineteen ostracod assemblage zones have been recognized: 1. Mongolocypris longicaudata-Cypridea Assemblage Zone, 2.Triangulicypris torsuosus-Triangulicypris torsuosus. nota Assemblage Zone, 3. Cypridea dekhoinensis-Cypridea gibbosa Assemblage Zone, 4.Cypridea nota-Sunliavia tumida Assemblage Zone, 5.Cypridea edentula-Lycopterocypris grandis Assemblage Zone, 6.Cypridea fuyuensis-Triangulicypris symmetrica Assemblage Zone, 7.Triangulicypris vestilus-Triangulicypris fusiformis-Triangulicypris pumilis Assemblage Zone, 8.Cypridea panda-Mongolocypris obscura Assemblage Zone, 9. Cypridea exornata-Cypridea dongfangensis Assemblage Zone, 10.Cypridea favosa-Mongolocypris tabulata Assemblage Zone, 11.Cypridea formosa-Cypridea sunghuajiangensis Assemblage Zone, 12. Cypridea anonyma-Candona fabiforma Assemblage Zone, 13.Cypridea gracila-Cypridea gunsulinensis Assemblage Zone, 14.Mongolocypris magna-Mongolocypris heiluntszianensis Assemblage Zone, 15.Cypridea liaukhenensis-Cypridea stellata Assemblage Zone, 16. Ilyocyprimorpha-Limnocypridea sunliaonensis-Periacanthella Assemblage Zone, 17. Strumosia inandita Asemblage-Zone, 18.Talicypridea amoena-Metacypris kaitunensis-Ziziphocypris simakovi Assemblage Zone, 19.Ilyocypris Assemblage Zone. Assemblage Zone 1 to 18 are belong to late Cretaceous, but 19 might constrained to the Latest Maastrichtian to the Earliset Danian.

Finite-size scaling above the upper critical dimension in Ising models with long-range interactions

NASA Astrophysics Data System (ADS)

Flores-Sola, Emilio J.; Berche, Bertrand; Kenna, Ralph; Weigel, Martin

2015-01-01

The correlation length plays a pivotal role in finite-size scaling and hyperscaling at continuous phase transitions. Below the upper critical dimension, where the correlation length is proportional to the system length, both finite-size scaling and hyperscaling take conventional forms. Above the upper critical dimension these forms break down and a new scaling scenario appears. Here we investigate this scaling behaviour by simulating one-dimensional Ising ferromagnets with long-range interactions. We show that the correlation length scales as a non-trivial power of the linear system size and investigate the scaling forms. For interactions of sufficiently long range, the disparity between the correlation length and the system length can be made arbitrarily large, while maintaining the new scaling scenarios. We also investigate the behavior of the correlation function above the upper critical dimension and the modifications imposed by the new scaling scenario onto the associated Fisher relation.

The Kramer deposit of southern California--Preliminary insights on the origins of zoned lacustrine evaporite borate deposits

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

Swihart, G.H.; McBay, E.H.; Smith, D.H.

1992-01-01

Lacustrine evaporite borate deposits span the range from mineralogically unzoned or poorly zoned to concentrically or complexly zoned types. Deposits often contain an inner ulexite or probertite (Na-Ca borates) zone and an outer colemanite (Ca borate) zone. A few deposits contain an innermost borax (Na borate) zone. Boron isotopic analyses of core material from the zoned borax-ulexite-colemanite Kramer deposit have been made with the aim of providing a better understanding of the processes of zone formation. Samples from 6 depths over a 63 foot interval in the borax zone yield a [delta] B-11 range of +0.1 to +2.3 permil. Twomore » samples in the portion of the ulexite zone below the borax zone, vertically separated from one another by 20 feet, yield identical results of [delta]B-11 = [minus]2.1 permit. Three ulexite samples from a 10 foot interval above the borax zone produced results in the range [delta]B-11 = [minus]4.6 to [minus]5.5 permil. A number of possible origins for ulexite at Kramer have been proposed: (1) primary precipitation from the lake brines; (2) postdepositional alteration of the borax zone margin by Ca-rich groundwater; (3) mixing of seeping lake brines and Ca-rich groundwater in muds around the lake. Given the small variation in B isotopic composition exhibited in the borax zone, mechanisms 1 and 2 would produce upper and lower portions of the ulexite zone with similar isotopic compositions. In the third scenario, the difference in composition of the upper and lower ulexites could be due to distance from the lake and relative proportions of seeped lake brine (B-11-rich) and clay adsorbed B (B-10-rich). Furthermore, the cotton ball form of the ulexite in this core is identical to that of ulexite forming today just beneath the surface of dry lakes in NV and CA.« less

Litho-kinematic facies model for large landslide deposits in arid settings

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

Yarnold, J.C.; Lombard, J.P.

1989-04-01

Reconnaissance field studies of six large landslide deposits in the S. Basin and Range suggest that a set of characteristic features is common to the deposits of large landslides in an arid setting. These include a coarse boulder cap, an upper massive zone, a lower disrupted zone, and a mixed zone overlying disturbed substrate. The upper massive zone is dominated by crackel breccia. This grades downward into a lower disrupted zone composed of a more matrix-rich breccia that is internally sheared, intruded by clastic dikes, and often contains a cataclasite layer at its base. An underlying discontinuous mixed zone ismore » composed of material from the overlying breccia mixed with material entrained from the underlying substrate. Bedding in the substrate sometimes displays folding and contortion that die out downward. The authors work suggests a spatial zonation of these characteristic features within many landslide deposits. In general, clastic dikes, the basal cataclasite, and folding in the substrate are observed mainly in distal parts of landslides. In most cases, total thickness, thickness of the basal disturbed and mixed zones, and the degree of internal shearing increase distally, whereas maximum clast size commonly decreases distally. Zonation of these features is interpreted to result from kinematics of emplacement that cause generally increased deformation in the distal regions of the landslide.« less

Shear wave reflectivity imaging of the Nazca-South America subduction zone: Stagnant slab in the mantle transition zone?

NASA Astrophysics Data System (ADS)

Contenti, Sean; Gu, Yu Jeffrey; Ökeler, Ahmet; Sacchi, Mauricio D.

2012-01-01

In this study we utilize over 5000 SS waveforms to investigate the high-resolution mantle reflectivity structure down to 1200 km beneath the South American convergent margin. Our results indicate that the dynamics of the Nazca subduction are more complex than previously suggested. The 410- and 660-km seismic discontinuities beneath the Pacific Ocean and Amazonian Shield exhibit limited lateral depth variations, but their depths vary substantially in the vicinity of the subducting Nazca plate. The reflection amplitude of the 410-km discontinuity is greatly diminished in a ˜1300-km wide region in the back-arc of the subducting plate, which is likely associated with a compositional heterogeneity on top of the upper mantle transition zone. The underlying 660-km discontinuity is strongly depressed, showing localized depth and amplitude variations both within and to the east of the Wadati-Benioff zone. The width of this anomalous zone (˜1000 km) far exceeds that of the high-velocity slab structure and suggesting significant slab deformation within the transition zone. The shape of the 660-km discontinuity and the presence of lower mantle reflectivity imply both stagnation and penetration are possible as the descending Nazca slab impinges upon the base of the upper mantle.

Latest Cretaceous and Paleocene extension in SE California

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

Tosdal, R.M.; Conrad, J.E.; Murphy, G.P.

1993-04-01

Two ductile deformations formed the 3.5-km-thick, south dipping American Girl shear zone in the Cargo Muchancho Mountains, SE California. The older event (D1) imprints crystalloblastic fabrics that record contractional strains at midcrustal depths in the Middle( ) and Late Jurassic. The second event (D2) is marked by superposed mylonitic fabrics that are coplanar and colinear with fabrics of D1. Small mylonitic shear zones of D2 cut undeformed rocks in the hanging wall of the American Girl shear zone. Folded sheets of Jurassic granite geneiss and kinematic indicators in mylonites indicative southward directed transport down the present dip of the foliationmore » during D2. [sup 40]Ar/[sup 39]Ar release spectrum on hornblende from undeformed upper-plate monzo-diorite (173 Ma, U-Pb zircon), about 2 km above the top of shear zone has a plateau age of 96.7[+-]0.9 Ma. In contrast, hornblende release spectra from granite gneiss about 200 m below the top of the shear zone and from hornblende gneiss about 3 km below the top of the shear zone are flat and have identical ages. Hornblende from monzodiorite at the base of the upper plate has a more complicated spectrum that is interpreted to indicate a cooling age of 60.4[+-]1.3 Ma.« less

Diagnostic heavy minerals in Plio-Pleistocene sediments of the Yangtze Coast, China with special reference to the Yangtze River connection into the sea

NASA Astrophysics Data System (ADS)

Chen, Jing; Wang, Zhanghua; Chen, Zhongyuan; Wei, Zixin; Wei, Taoyuan; Wei, Wei

2009-12-01

This present study revealed five heavy mineral zones in the Yangtze coastal borehole sediments. Ilmenite, garnet and zircon suite of Zone I of the Pliocene characterizes the derivation of basaltic bedrock and local andesitic-granitic rocks. Indicative limonite in the Zone I sediments formed as alluvial fan facies shows strong chemical weathering. The assemblage of amphibole, straurolite, kyanite and idocrase of metamorphic derivation, together with a few zircon and tourmaline of andesitic-granitic origin in Zone II, represents the extension of sediment sources to the lower and middle Yangtze basin in Early Pleistocene as the study area subsided. Also, the braided to meandering riverine facies demonstrates a longer distance sediment transport. Few heavy minerals remained in Zone III of Mid-Pleistocene, when mottled thicker stiff mud occurred as the lacustrine facies, suggesting a quasi-coastal floodplain with lower capability of sediment transport. Heavy minerals appeared significant and continuous in Zone IV of Late Pleistocene, when changing to the shallow marine facies, inferring much extended sediment sources to the upper Yangtze. Hypersthene, identified primarily in Zone IV, was closely associated with the Er-Mei Mountain tholeiite basalt of the upper Yangtze. Heavy minerals of Zone V remained almost the same as IV during Holocene, when the modern delta evolved. The heavy minerals suggested the timing of the Yangtze connection to the sea at ca 0.12 Ma BP.

Depositional sequence stratigraphy and architecture of the cretaceous ferron sandstone: Implications for coal and coalbed methane resources - A field excursion

USGS Publications Warehouse

Garrison, J.R.; Van Den, Bergh; Barker, C.E.; Tabet, D.E.

1997-01-01

This Field Excursion will visit outcrops of the fluvial-deltaic Upper Cretaceous (Turonian) Ferron Sandstone Member of the Mancos Shale, known as the Last Chance delta or Upper Ferron Sandstone. This field guide and the field stops will outline the architecture and depositional sequence stratigraphy of the Upper Ferron Sandstone clastic wedge and explore the stratigraphic positions and compositions of major coal zones. The implications of the architecture and stratigraphy of the Ferron fluvial-deltaic complex for coal and coalbed methane resources will be discussed. Early works suggested that the southwesterly derived deltaic deposits of the the upper Ferron Sandstone clastic wedge were a Type-2 third-order depositional sequence, informally called the Ferron Sequence. These works suggested that the Ferron Sequence is separated by a type-2 sequence boundary from the underlying 3rd-order Hyatti Sequence, which has its sediment source from the northwest. Within the 3rd-order depositional sequence, the deltaic events of the Ferron clastic wedge, recognized as parasequence sets, appear to be stacked into progradational, aggradational, and retrogradational patterns reflecting a generally decreasing sediment supply during an overall slow sea-level rise. The architecture of both near-marine facies and non-marine fluvial facies exhibit well defined trends in response to this decrease in available sediment. Recent studies have concluded that, unless coincident with a depositional sequence boundary, regionally extensive coal zones occur at the tops of the parasequence sets within the Ferron clastic wedge. These coal zones consist of coal seams and their laterally equivalent fissile carbonaceous shales, mudstones, and siltstones, paleosols, and flood plain mudstones. Although the compositions of coal zones vary along depositional dip, the presence of these laterally extensive stratigraphic horizons, above parasequence sets, provides a means of correlating and defining the tops of depositional parasequence sets in both near-marine and non-marine parts of fluvial-deltaic depositional sequences. Ongoing field studies, based on this concept of coal zone stratigraphy, and detailed stratigraphic mapping, have documented the existence of at least 12 parasequence sets within the Last Chance delta clastic wedge. These parasequence sets appear to form four high frequency, 4th-order depositional sequences. The dramatic erosional unconformities, associated with these 4th-order sequence boundaries, indicate that there was up to 20-30 m of erosion, signifying locally substantial base-level drops. These base-level drops were accompanied by a basin ward shift in paleo-shorelines by as much as 5-7 km. These 4th-order Upper Ferron Sequences are superimposed on the 3rd-order sea-level rise event and the 3rd-order, sediment supply/accommodation space driven, stratigraphie architecture of the Upper Ferron Sandstone. The fluvial deltaic architecture shows little response to these 4th-order sea-level events. Coal zones generally thicken landward relative to the mean position of the landward pinch-out of the underlying parasequence set, but after some distance landward, they decrease in thickness. Coal zones also generally thin seaward relative to the mean position of the landward pinch-out of the underlying parasequence set. The coal is thickest in the region between this landward pinch-out and the position of maximum zone thickness. Data indicate that the proportion of coal in the coal zone decreases progressively landward from the landward pinch-out. The effects of differential compaction and differences in original pre-peat swamp topography have the effect of adding perturbations to the general trends. These coal zone systematics have major impact on approaches to exploration and production, and the resource accessment of both coal and coalbed methane.

Tank 241-AX-104 upper vadose zone cone penetrometer demonstration sampling and analysis plan

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

FIELD, J.G.

1999-02-02

This sampling and analysis plan (SAP) is the primary document describing field and laboratory activities and requirements for the tank 241-AX-104 upper vadose zone cone penetrometer (CP) demonstration. It is written in accordance with Hanford Tank Initiative Tank 241-AX-104 Upper Vadose Zone Demonstration Data Quality Objective (Banning 1999). This technology demonstration, to be conducted at tank 241-AX-104, is being performed by the Hanford Tanks Initiative (HTI) Project as a part of Tank Waste Remediation System (TWRS) Retrieval Program (EM-30) and the Office of Science and Technology (EM-50) Tanks Focus Area. Sample results obtained as part of this demonstration will providemore » additional information for subsequent revisions to the Retrieval Performance Evaluation (RPE) report (Jacobs 1998). The RPE Report is the result of an evaluation of a single tank farm (AX Tank Farm) used as the basis for demonstrating a methodology for developing the data and analyses necessary to support making tank waste retrieval decisions within the context of tank farm closure requirements. The RPE includes a study of vadose zone contaminant transport mechanisms, including analysis of projected tank leak characteristics, hydrogeologic characteristics of tank farm soils, and the observed distribution of contaminants in the vadose zone in the tank farms. With limited characterization information available, large uncertainties exist as to the nature and extent of contaminants that may exist in the upper vadose zone in the AX Tank Farm. Traditionally, data has been collected from soils in the vadose zone through the installation of boreholes and wells. Soil samples are collected as the bore hole is advanced and samples are screened on site and/or sent to a laboratory for analysis. Some in-situ geophysical methods of contaminant analysis can be used to evaluate radionuclide levels in the soils adjacent to an existing borehole. However, geophysical methods require compensation for well casing interference and soil moisture content and may not be successful in some conditions. In some cases the level of interference must be estimated due to uncertainties regarding the materials used in well construction and soil conditions, Well casing deployment used for many in-situ geophysical methods is relatively expensive and geophysical methods do not generally provide real time values for contaminants. In addition, some of these methods are not practical within the boundaries of the tank farm due to physical constraints, such as underground piping and other hardware. The CP technologies could facilitate future characterization of vadose zone soils by providing vadose zone data in near real-time, reducing the number of soil samples and boreholes required, and reducing characterization costs.« less

Anaemia only causes a small reduction in the upper critical temperature of sea bass: is oxygen delivery the limiting factor for tolerance of acute warming in fishes?

PubMed

Wang, Tobias; Lefevre, Sjannie; Iversen, Nina K; Findorf, Inge; Buchanan, Rasmus; McKenzie, David J

2014-12-15

To address how the capacity for oxygen transport influences tolerance of acute warming in fishes, we investigated whether a reduction in haematocrit, by means of intra-peritoneal injection of the haemolytic agent phenylhydrazine, lowered the upper critical temperature of sea bass. A reduction in haematocrit from 42±2% to 20±3% (mean ± s.e.m.) caused a significant but minor reduction in upper critical temperature, from 35.8±0.1 to 35.1±0.2°C, with no correlation between individual values for haematocrit and upper thermal limit. Anaemia did not influence the rise in oxygen uptake between 25 and 33°C, because the anaemic fish were able to compensate for reduced blood oxygen carrying capacity with a significant increase in cardiac output. Therefore, in sea bass the upper critical temperature, at which they lost equilibrium, was not determined by an inability of the cardio-respiratory system to meet the thermal acceleration of metabolic demands. © 2014. Published by The Company of Biologists Ltd.

Scaffolding Critical Thinking in the Zone of Proximal Development

ERIC Educational Resources Information Center

Wass, Rob; Harland, Tony; Mercer, Alison

2011-01-01

This paper explores student experiences of learning to think critically. Twenty-six zoology undergraduates took part in the study for three years of their degree at the University of Otago, New Zealand. Vygotsky's developmental model of the Zone of Proximal Development (ZPD) provided a framework as we examined how critical thinking was developed.…

Microbial community of cyanobacteria mats in the intertidal zone of oil-polluted coast of Saudi Arabia.

PubMed

Al-Thukair, A A; Abed, R M M; Mohamed, L

2007-02-01

Cyanobacterial mats are found at various locations along the coast of the Eastern Province of Saudi Arabia. Those mats were affected by severe oil pollution following 1991 oil spill. In this study, samples from Abu Ali Island were collected at three selected sampling sites across the intertidal zone (Lower, Middle, and Upper) in order to understand the effect of extreme environmental conditions of high salinity, temperature and desiccation on distribution of cyanobacteria along the oil polluted intertidal zone. Our investigation of composition of cyanobacteria and diatoms was carried out using light microscopy, and Denaturant Gradient Gel Electrophoresis (DGGE) technique. Light microscopy identification revealed dominant cyanobacteria to be affiliated with genera Phormidium, Microcoleus, and Schizothrix, and to a lesser extent with Oscillatoria, Halothece, and various diatom species. The analysis of DGGE of PCR-amplified 16S rRNA fragments showed that the diversity of cyanobacteria decreases as we proceed from the lower to the upper intertidal zone. Accordingly, the tidal regime, salinity, elevated ambient air temperature, and desiccation periods have a great influence on the distribution of cyanobacterial community in the oil polluted intertidal zone of Abu Ali Island.

Organization of cortical microtubules in graviresponding maize roots

NASA Technical Reports Server (NTRS)

Blancaflor, E. B.; Hasenstein, K. H.

1993-01-01

Immunofluorescence labeling of cortical microtubules (MTs) was used to investigate the relationship between MT arrangement and changes in growth rate of the upper and lower sides of horizontally placed roots of maize (Zea mays L. cv. Merit). Cap cells and cells of the elongation zone of roots grown vertically in light or darkness showed MT arrangements that were transverse (perpendicular) to the growth direction. Microtubules of cells basal to the elongation zone typically showed oblique orientation. Two hours after horizontal reorientation, cap cells of gravicompetent, light-grown and curving roots contained MTs parallel to the gravity vector. The MT arrangement on the upper side of the elongation zone remained transverse but the MTs of the outer four to five layers of cortical cells along the lower side of the elongation zone showed reorientation parallel to the axis of the root. The MTs of the lower epidermis retained their transverse orientation. Dark-grown roots did not curve and did not show reorientation of MTs in cells of the root cap or elongation zone. The data indicate that MT depolymerization and reorientation is correlated with reduction in growth rate, and that MT reorientation is one of the steps of growth control of graviresponding roots.

New U-Pb zircon ages and the duration and division of Devonian time

USGS Publications Warehouse

Tucker, R.D.; Bradley, D.C.; Ver Straeten, C.A.; Harris, A.G.; Ebert, J.R.; McCutcheon, S.R.

1998-01-01

Newly determined U-Pb zircon ages of volcanic ashes closely tied to biostratigraphic zones are used to revise the Devonian time-scale. They are: 1) 417.6 ?? 1.0 Ma for an ash within the conodont zone of Icriodus woschmidti/I. w. hesperius Lochkovian); 2) 408.3 ?? 1.9 Ma for an ash of early Emsian age correlated with the conodont zones of Po. dehiscens--Lower Po. inversus; 3) 391.4 ?? 1.8 Ma for an ash within the Po. c. costatus Zone and probably within the upper half of the zone (Eifelian); and 4) 381.1 ?? 1.3 Ma for an ash within the range of the Frasnian conodont Palmatolepis punctata (Pa. punctata Zone to Upper Pa. hassi Zone). U-Pb zircon ages for two rhyolites bracketing a palyniferous bed of the pusillites-lepidophyta spore zone, are dated at 363.8 ?? 2.2 Ma and 363 ?? 2.2 Ma and 363.4 ?? 1.8 Ma, respectively, suggesting an age of ~363 Ma for a level within the late Famennian Pa. g. expansa Zone. These data, together with other published zircon ages, suggest that the base and top of the Devonian lie close to 418 Ma and 362 Ma, respectively, thus lengthening the period of ~20% over current estimates. We suggest that the duration of the Middle Devonian (Eifelian and Givitian) is rather brief, perhaps no longer than 11.5 Myr (394 Ma-382.5 Ma), and that the Emsian and Famennian are the longest stages in the period with estimated durations of ~15.5 Myr and 14.5 Myr, respectively.

New Orogenic Model for Taiwan Collision Zone Inferred From Three-dimensional P- and S-wave Velocity Structures and Seismicity

NASA Astrophysics Data System (ADS)

Nagai, S.; Hirata, N.; Sato, H.

2008-12-01

The island of Taiwan is located in the site of ongoing arc-continent collision zone between the Philippine Sea Plate (PSP) and the Eurasian Plate (EUP). Numerous geophysical and geological studies are done in and around Taiwan to develop various models to explain the tectonic processes in the Taiwan region. However, their details have not been known enough, especially under the Central Range. We suggest a new orogenic model for Taiwan orogeny, named 'Upper Crustal Stacking Model', inferred from our tomographic images using three temporary seismic networks with the Central Weather Bureau Seismic Network. These three temporary networks are the aftershock observation after the 1999 Chi-Chi Taiwan earthquake and two dense array observations across central and southern Taiwan, respectively. Tomographic images by the double-difference tomography [Zhang and Thurber, 2003] show a lateral alternate variation of high- and low-velocity, which are well correlated to surface geology and separated by east-dipping boundaries. These images have reliable high-resolution by dense arrays to be able to discuss this alternate variation. We found three high-velocity zones (> 6.0km/s). The westernmost zone corresponds to the subducting EUP. Other two zones are located beneath the Hsuehshan Range and the Eastern Central Range with trends of eastward dipping, respectively. And, we could image low-velocity zone located beneath Backbone Range between the two high-velocity zones clearly. We interpret that these east-dipping high- and low-velocity zones can be divided into two layered blocks and the subducting EUP, each of which consists of a high-velocity body under low-velocity one. Layered blocks can be interpreted as stacked thrust sheets between the subducting EUP and the Northern Luzon Arc, a part of PSP. These thrust sheets are parts of upper- and mid-crust detached from the subducting EUP. The model of continental subduction followed by buoyancy-driven exhumation can explain the existence of stacked thrust sheets. Thus we propose a new orogenic model, as referred to as the 'Upper Crustal Stacking Model'.

Upper Paleocene and lowermost Eocene angiosperm pollen biostratigraphy of the eastern Gulf Coast and Virginia

USGS Publications Warehouse

Frederiksen, N.O.

1998-01-01

Strata comprising most of the upper Paleocene in eastern North America are divided into two new pollen zones, the Carya and Platycarya platycaryoides Interval Zones. Pollen data have proven to be important for correlations between Alabama-western Georgia and eastern Mississippi and between the eastern Gulf Coast and Virginia. Migration of tropical plant taxa from the Caribbean to the Gulf Coast began at least 4 m.y. before the end of the Paleocene. The Terminal Paleocene Extinction Event, accompanied by a distinct pulse of plant immigration from Europe, began several hundred thousand years before the end of the Paleocene.

The 12 September 1999 Upper East Rift Zone dike intrusion at Kilauea Volcano, Hawaii

USGS Publications Warehouse

Cervelli, Peter; Segall, P.; Amelung, F.; Garbeil, H.; Meertens, C.; Owen, S.; Miklius, Asta; Lisowski, M.

2002-01-01

Deformation associated with an earthquake swarm on 12 September 1999 in the Upper East Rift Zone of Kilauea Volcano was recorded by continuous GPS receivers and by borehole tiltmeters. Analyses of campaign GPS, leveling data, and interferometric synthetic aperture radar (InSAR) data from the ERS-2 satellite also reveal significant deformation from the swarm. We interpret the swarm as resulting from a dike intrusion and model the deformation field using a constant pressure dike source. Nonlinear inversion was used to find the model that best fits the data. The optimal dike is located beneath and slightly to the west of Mauna Ulu, dips steeply toward the south, and strikes nearly east-west. It is approximately 3 by 2 km across and was driven by a pressure of ??? 15 MPa. The total volume of the dike was 3.3 x 106 m3. Tilt data indicate a west to east propagation direction. Lack of premonitory inflation of Kilauea's summit suggests a passive intrusion; that is, the immediate cause of the intrusion was probably tensile failure in the shallow crust of the Upper East Rift Zone brought about by persistent deep rifting and by continued seaward sliding of Kilauea's south flank.

Three-dimensional frictional plastic strain partitioning during oblique rifting

NASA Astrophysics Data System (ADS)

Duclaux, Guillaume; Huismans, Ritske S.; May, Dave

2017-04-01

Throughout the Wilson cycle the obliquity between lithospheric plate motion direction and nascent or existing plate boundaries prompts the development of intricate three-dimensional tectonic systems. Where oblique divergence dominates, as in the vast majority of continental rift and incipient oceanic domains, deformation is typically transtensional and large stretching in the brittle upper crust is primarily achieved by the accumulation of displacement on fault networks of various complexity. In continental rift depressions such faults are initially distributed over tens to hundreds of kilometer-wide regions, which can ultimately stretch and evolve into passive margins. Here, we use high-resolution 3D thermo-mechanical finite element models to investigate the relative timing and distribution of localised frictional plastic deformation in the upper crust during oblique rift development in a simplified layered lithosphere. We vary the orientation of a wide oblique heterogeneous weak zone (representing a pre-existing geologic feature like a past orogenic domain), and test the sensitivity of the shear zones orientation to a range of noise distribution. These models allow us to assess the importance of material heterogeneities for controlling the spatio-temporal shear zones distribution in the upper crust during oblique rifting, and to discuss the underlying controls governing oblique continental breakup.

Mantle Upwellings Below the Ibero-Maghrebian Region with a Common Deep Source from P Travel-time Tomography

NASA Astrophysics Data System (ADS)

Civiero, C.; Custodio, S.; Silveira, G. M.; Rawlinson, N.; Arroucau, P.

2017-12-01

The processes responsible for the geodynamical evolution of the Ibero-Maghrebian domain are still enigmatic. Several geophysical studies have improved our understanding of the region, but no single model has been accepted yet. This study takes advantage of the dense station networks deployed from France in the north to Canary Islands and Morocco in the south to provide a new high-resolution P-wave velocity model of the structure of the upper-mantle and top of the lower mantle. These images show subvertical small-scale upwellings below Atlas Range, Canary Islands and Central Iberia that seem to cross the transition zone. The results, together with geochemical evidence and a comparison with previous global tomographic models, reveal the ponding or flow of deep-plume material beneath the transition zone, which seems to feed upper-mantle "secondary" pulses. In the upper mantle the plumes, in conjunction with the subduction-related upwellings, allow the hot mantle to rise in the surrounding zones. During its rising, the mantle interacts with horizontal SW slab-driven flow which skirts the Alboran slab and connects with the mantle upwelling below Massif Central through the Valencia Trough rift.

Life on the boundary: Environmental factors as drivers of habitat distribution in the littoral zone

NASA Astrophysics Data System (ADS)

Cefalì, Maria Elena; Cebrian, Emma; Chappuis, Eglantine; Pinedo, Susana; Terradas, Marc; Mariani, Simone; Ballesteros, Enric

2016-04-01

The boundary between land and sea, i.e. the littoral zone, is home to a large number of habitats whose distribution is primarily driven by the distance to the sea level but also by other environmental factors such as littoral's geomorphological features, wave exposure, water temperature or orientation. Here we explore the relative importance of those major environmental factors that drive the presence of littoral rocky habitats along 1100 Km of Catalonia's shoreline (Spain, NW Mediterranean) by using Geographic Information Systems and Generalized Linear Models. The distribution of mediolittoral and upper infralittoral habitats responded to different environmental factors. Mediolittoral habitats showed regional differences drawn by sea-water temperature and substrate type. Wave exposure (hydrodynamism), slope and geological features were only relevant to those mediolittoral habitats with specific environmental needs. We did not find any regional pattern of distribution in upper infralittoral habitats, and selected factors only played a moderate role in habitat distribution at the local scale. This study shows for the first time that environmental factors determining habitat distribution differ within the mediolittoral and the upper infralittoral zones and provides the basis for further development of models oriented at predicting the distribution of littoral marine habitats.

Tularosa Basin Play Fairway Analysis: Partial Basin and Range Heat and Zones of Critical Stress Maps

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

Adam Brandt

Interpolated maps of heat flow, temperature gradient, and quartz geothermometers are included as TIF files. Zones of critical stress map is also included as a TIF file. The zones are given a 5km diameter buffer. The study area is only a part of the Basin and Range, but it does includes the Tularosa Basin.

Partial melting kinetics of plagioclase-diopside pairs

NASA Astrophysics Data System (ADS)

Tsuchiyama, Akira

1985-09-01

Partial melting experiments on plagioclase (An60) and diopside have been carried out using pairs of large crystals to investigate textures and kinetics of melting. The experiments were done at one atmosphere pressure as a function of temperature (1,190 1,307° C) and time (1.5 192 h). Melting took place mainly at the plagioclase-diopside contact planes. Reaction zones composed of fine mixtures of calcic plagioclase and melt were developed from the surface of the plagioclase crystal inward. There exists a critical temperature, below which only a few % melting can occur over the duration of the experiments. This sluggish melting is caused by slow NaSi-CaAl diffusion in plagioclase, because the plagioclase crystal must change its composition to produce albite-rich cotectic melts. Diffusion in the solid also affects the chemical composition of the melts. During initial melting, potassium is preferentially extracted from plagioclase because K-Na diffusion in plagioclase is faster than that of NaSi-CaAl. This also causes a shift in the cotectic compositions. Above the “critical temperature”, on the other hand, melting is promoted by a metastable reaction in which the plagioclase composition does not change, and which produces melts with compositional gradients along the original An60-diopside tie line. The critical temperature is determined by the intersection of the cotectic and the An60-diopside tie line. Interdiffusion coefficients of plagioclase-diopside components in the melt are estimated from melting rates above the critical temperature by using a simplified steady-state diffusion model (e.g., 10-8 cm2/sec at 1,300° C). Many examples of reaction zones due to partial melting have been described as spongy or fingerprint-like textures in xenoliths. Metastable melting above the critical temperature is considered to take place in natural melting where there is a high degree of melting. However, we cannot exclude the possibility of disequilibrium created by sluggish melting controlled by diffusion in the minerals. If melting occurs close to the solidus, this process can be important even for partial melting in the upper mantle.

The upper critical field of filamentary Nb3Sn conductors

NASA Astrophysics Data System (ADS)

Godeke, A.; Jewell, M. C.; Fischer, C. M.; Squitieri, A. A.; Lee, P. J.; Larbalestier, D. C.

2005-05-01

We have examined the upper critical field of a large and representative set of present multifilamentary Nb3Sn wires and one bulk sample over a temperature range from 1.4 K up to the zero-field critical temperature. Since all present wires use a solid-state diffusion reaction to form the A15 layers, inhomogeneities with respect to Sn content are inevitable, in contrast to some previously studied homogeneous samples. Our study emphasizes the effects that these inevitable inhomogeneities have on the field-temperature phase boundary. The property inhomogeneities are extracted from field-dependent resistive transitions which we find broaden with increasing inhomogeneity. The upper 90%-99% of the transitions clearly separates alloyed and binary wires but a pure, Cu-free binary bulk sample also exhibits a zero-temperature critical field that is comparable to the ternary wires. The highest μ0Hc2 detected in the ternary wires are remarkably constant: The highest zero-temperature upper critical fields and zero-field critical temperatures fall within 29.5±0.3 and 17.8±0.3K, respectively, independent of the wire layout. The complete field-temperature phase boundary can be described very well with the relatively simple Maki-DeGennes model using a two-parameter fit, independent of composition, strain state, sample layout, or applied critical state criterion.

Preliminary palynological zonation of the Chinle formation, southwestern U.S.A., and its correlation to the Newark supergroup (eastern U.S.A.)

USGS Publications Warehouse

Litwin, R.J.; Traverse, A.; Ash, S.R.

1991-01-01

Three informal palynological assemblage zones can be distinguished in samples from Chinle Formation outcrops in Utah, Arizona and New Mexico. The oldest zone (zone I) is in the Temple Mountain Member in southeastern Utah; the middle zone (zone II) is in the Shinarump, Moss Back, Monitor Butte and (lower part of the) Petrified Forest Members (Utah, Arizona and New Mexico); the youngest zone (zone III) is in the upper Petrified Forest Member and silstone member in Arizona and Utah and the silstone member in northcentral New Mexico. Present palynological evidence suggests that Chinle deposition on the Colorado Plateau began locally in late Carnian time and continued at least into the early part of Norian time of the Late Triassic period. Because the upper boundary of the Chinle Formation is an unconformity and the overlying formations are palynologically barren, the length of time represented by this stratigraphic hiatus is not known with certainty. Current palynological evidence suggests, however, that the unconformity at the top of the Chinle cannot be older than early Norian nor younger than Hettangian. Zones I, II and III can now be recognized in the palynomorph assemblage sequences from the Eastern Mesozoic basins, which modifies earlier palynological zonations for the lower portions of the Newark Supergroup. This is based on our identification of palynomorphs not previously known from portions of the Newark Supergroup and the discovery that specific biomarker taxa combinations are the same for both the western and eastern palynomorph sequences. At present palynomorph assemblages from the Chinle Formation and Newark Supergroup compare more closely for zones II and III than they do for zone I, but research is still in progress. ?? 1991.

Hydrogeologic evaluation of the Upper Floridan aquifer in the southwestern Albany area, Georgia

USGS Publications Warehouse

Warner, Debbie

1997-01-01

A cooperative study by the Albany Water, Gas, and Light Commission and the U.S. Geological Survey was conducted to evaluate the hydrogeology of the Upper Floridan aquifer in an area southwest of Albany and west of the Flint River in Dougherty County, Ga. The study area lies in the Dougherty Plain district of the Coastal Plain physiographic province. In this area, the Upper Floridan aquifer is comprised of the upper Eocene Ocala Limestone, confined below by the middle Eocene Lisbon Formation, and semiconfined above by the undifferentiated Quaternary overburden. The overburden ranges in thickness from about 30 to 50 feet and consists of fine to coarse quartz sand, clayey sand, sandy clay, and clay. The Upper Floridan aquifer has been subdivided into an upper water-bearing zone and a lower water-bearing zone based on differences in lithology and yield. In the study area, the upper water-bearing zone generally consists of dense, highly weathered limestone of low permeability and ranges in thickness from 40 to 80 feet. The lower water-bearing zone consists of hard, slightly weathered limestone that exhibits a high degree of secondary permeability that has developed along fractures and joints, and ranges in thickness from about 60 to 80 feet. Borehole geophysical logs and borehole video surveys indicate two areas of high permeability in the lower water-bearing zone-one near the top and one near the base of the zone. A wellfield consisting of one production well and five observation-well clusters (one deep, intermediate, and shallow well in each cluster) was constructed for this study. Spinner flowmeter tests were conducted in the production well between the depths of 110 and 140 feet below land surface to determine the relative percentages of water contributed by selected vertical intervals of the lower water-bearing zone. Pumping rates during these tests were 1,080, 2,200, and 3,400 gallons per minute. The results of these pumping tests show that the interval between 118 and 124 feet below land surface contributes a significant percentage of the total yield to the well. An aquifer test was conducted by pumping the production well at a constant rate of 3,300 gallons per minute for about 49 hours. Time-dependent water-level data were collected throughout the pumping and recovery phases of the test in the pumped well and the observation wells. The maximum measured drawdown in the observation wells was about 2.6 ft. At about 0.5 mile from the pumped well, there was little measurable effect from pumping. Water levels increased during the test in wells located within about 3.75 miles of the Flint River (about 0.5 miles east of the pumping well). This water-level increase correlated with a 3.5-feet increase in the stage of the Flint River. The hydraulic characteristics of the Upper Floridan aquifer were evaluated using the Hantush-Jacob curve-matching and Jacob straight-line methods. Using the Hantush-Jacob method, values for transmissivity ranged from about 120,000 to 506,000 feet squared per day; values for storage coefficient ranged from 1.4 x 10-4 to 6.3 x 10-4; and values for vertical hydraulic conductivity of the overlying sediments ranged from 4.9 to 6.8 feet per day. Geometric averages for these values of transmissivity, storage coefficient, and vertical hydraulic conductivity were calculated to be 248,000 feet squared per day, 2.7 x 10-4, and 5.5 feet per day, respectively. If a dual porosity aquifer model (fracture flow plus matrix flow) is assumed instead of leakage, and the Jacob straight-line method is used with late time-drawdown data, the calculated transmissivity of the fractures ranged from about 233,000 to 466,000 feet squared per day; and storage coefficient of the fractures plus the matrix ranged from 5.1 x 10-4 to 2.9 x 10-2.

Analysing the mechanisms of soil water and vapour transport in the desert vadose zone of the extremely arid region of northern China

NASA Astrophysics Data System (ADS)

Du, Chaoyang; Yu, Jingjie; Wang, Ping; Zhang, Yichi

2018-03-01

The transport of water and vapour in the desert vadose zone plays a critical role in the overall water and energy balances of near-surface environments in arid regions. However, field measurements in extremely dry environments face many difficulties and challenges, so few studies have examined water and vapour transport processes in the desert vadose zone. The main objective of this study is to analyse the mechanisms of soil water and vapour transport in the desert vadose zone (depth of ∼350 cm) by using measured and modelled data in an extremely arid environment. The field experiments are implemented in an area of the Gobi desert in northwestern China to measure the soil properties, daily soil moisture and temperature, daily water-table depth and temperature, and daily meteorological records from DOYs (Days of Year) 114-212 in 2014 (growing season). The Hydrus-1D model, which simulates the coupled transport of water, vapour and heat in the vadose zone, is employed to simulate the layered soil moisture and temperature regimes and analyse the transport processes of soil water and vapour. The measured results show that the soil water and temperatures near the land surface have visible daily fluctuations across the entire soil profile. Thermal vapour movement is the most important component of the total water flux and the soil temperature gradient is the major driving factor that affects vapour transport in the desert vadose zone. The most active water and heat exchange occurs in the upper soil layer (depths of 0-25 cm). The matric potential change from the precipitation mainly re-draws the spatio-temporal distribution of the isothermal liquid water in the soil near the land surface. The matric potential has little effect on the isothermal vapour and thermal liquid water flux. These findings offer new insights into the liquid water and vapour movement processes in the extremely arid environment.

Soil water dynamics during precipitation in genetic horizons of Retisol

NASA Astrophysics Data System (ADS)

Zaleski, Tomasz; Klimek, Mariusz; Kajdas, Bartłomiej

2017-04-01

Retisols derived from silty deposits dominate in the soil cover of the Carpathian Foothills. The hydrophysical properties of these are determined by the grain-size distribution of the parent material and the soil's "primary" properties shaped in the deposition process. The other contributing factors are the soil-forming processes, such as lessivage (leaching of clay particles), and the morphogenetic processes that presently shape the relief. These factors are responsible for the "secondary" differentiation of hydrophysical properties across the soil profile. Both the primary and secondary hydrophysical properties of soils (the rates of water retention, filtration and infiltration, and the moisture distribution over the soil profile) determine their ability to take in rainfall, the amount of rainwater taken in, and the ways of its redistribution. The aims of the study, carried out during 2015, were to investigate the dynamics of soil moisture in genetic horizons of Retisol derived from silty deposits and to recognize how fast and how deep water from precipitation gets into soil horizons. Data of soil moisture were measured using 5TM moisture and temperature sensor and collected by logger Em50 (Decagon Devices USA). Data were captured every 10 minutes from 6 sensors at depths: - 10 cm, 20 cm, 40 cm, 60 cm and 80 cm. Precipitation data come from meteorological station situated 50 m away from the soil profile. Two zones differing in the type of water regime were distinguished in Retisol: an upper zone comprising humic and eluvial horizons, and a lower zone consisting of illuvial and parent material horizons. The upper zone shows smaller retention of water available for plants, and relatively wide fluctuations in moisture content, compared to the lower zone. The lower zone has stable moisture content during the vegetation season, with values around the water field capacity. Large changes in soil moisture were observed while rainfall. These changes depend on the volume of the precipitation and soil moisture before the precipitation. The following changes of moisture in the soil profile during precipitation were distinguished: if soil moisture in upper zone horizons oscillates around field capacity (higher than 0.30 m3ṡm-3) there is an evident increase in soil moisture also in the lower zone horizons. If soil moisture in the upper zone horizons is much lower than the field capacity (less than 0.20 m3ṡm-3), the soil moisture in the lower zone has very little fluctuations. The range of wetting front in the soil profile depends on the volume of the precipitation and soil moisture. The heavier precipitation, the wetting front in soil profile reaches deeper horizons. The wetter the soil is, the faster soil moisture in the deeper genetic horizons increase. This Research was financed by the Ministry of Science and Higher Education of the Republic of Poland, DS No. 3138/KGiOG/2016.

Spatio-temporal variation in distribution of aquatic species and their habitats in a reservoir transition zone

Treesearch

Andy Dolloff; Craig Roghair; Colin Krause; John Moran; Allison Cochran; Mel Warren; Susan Adams; Wendell Haag

2016-01-01

Dams convert riverine habitat to a series of reaches or zones where differences in flow, habitat, and biota, both downstream and in reservoirs, are obvious and well described. At the upstream extent of a reservoir, however, is a transitional reach or zone that contains characteristics of riverine habitat both in the upper reservoir and in tributaries connected to the...

Foraminiferal and radiolarian biostratigraphy of the youngest (Late Albian through Late Cenomanian) sediments of the Tatra massif, Central Western Carpathians

NASA Astrophysics Data System (ADS)

Bąk, Krzysztof; Bąk, Marta

2013-06-01

Bąk, K. and Bąk M. 2013. Foraminiferal and radiolarian biostratigraphy of the youngest (Late Albian through Late Cenomanian) sediments of the Tatra massif, Central Western Carpathians. Acta Geologica Polonica, 63 (2), 223-237. Warszawa. The foraminiferal and radiolarian biostratigraphy of selected sections of the Zabijak Formation, the youngest sediments of the Tatra massif (Central Western Carpathians), have been studied. Benthic foraminifers, mainly agglutinated species, occur abundantly and continuously throughout the studied succession, while planktic foraminifers are generally sparse. Five planktic and two benthic foraminiferal zones have been recognized. The marly part of the Zabijak Formation comprises the Pseudothalmanninella ticinensis (Upper Albian) through the Rotalipora cushmani (Upper Cenomanian) planktic foraminiferal zones, and the Haplophragmoides nonioninoides and Bulbobaculites problematicus benthic foraminiferal zones. The radiolarians were recognized exclusively in the Lower Cenomanian part of the formation.

Stratification of welding fumes and grinding particles in a large factory hall equipped with displacement ventilation.

PubMed

Niemelä, R; Koskela, H; Engström, K

2001-08-01

The purpose of the study was to investigate the performance of displacement ventilation in a large factory hall where large components of stainless steel for paper, pulp and chemical industries were manufactured. The performance of displacement ventilation was evaluated in terms of concentration distributions of welding fumes and grinding particles, flow field of the supply air and temperature distributions. Large differences in vertical stratification patterns between hexavalent chromium (Cr(VI)) and other particulate contaminants were observed. The concentration of Cr(VI) was notably lower in the zone of occupancy than in the upper part of the factory hall, whereas the concentrations of total airborne particles and trivalent chromium (Cr(III)) were higher in the occupied zone than in the upper zone. The stratification of Cr(VI) had the same tendency as the air temperature stratification caused by the displacement flow field.

Hydrogeologic framework and geologic structure of the Floridan aquifer system and intermediate confining unit in the Lake Okeechobee area, Florida

USGS Publications Warehouse

Reese, Ronald S.

2014-01-01

The successful implementation of aquifer storage and recovery (ASR) as a water-management tool requires detailed information on the hydrologic and hydraulic properties of the potential water storage zones. This report presents stratigraphic and hydrogeologic sections of the upper part of the Floridan aquifer system and the overlying confining unit or aquifer system in the Lake Okeechobee area, and contour maps of the upper contacts of the Ocala Limestone and the Arcadia Formation, which are represented in the sections. The sections and maps illustrate hydrogeologic factors such as confinement of potential storage zones, the distribution of permeability within the zones, and geologic features that may control the efficiency of injection, storage, and recovery of water, and thus may influence decisions on ASR activities in areas of interest to the Comprehensive Everglades Restoration Plan.

Results of coalbed-methane drilling, Meadowfill Landfill, Harrison County, West Virginia: Chapter G.4 in Coal and petroleum resources in the Appalachian basin: distribution, geologic framework, and geochemical character

USGS Publications Warehouse

Ruppert, Leslie F.; Trippi, Michael H.; Fedorko, Nick; Grady, William C.; Eble, Cortland F.; Schuller, William A.; Ruppert, Leslie F.; Ryder, Robert T.

2014-01-01

Methane contents of desorbed gas from coal samples in the Meadowfill Landfill study area ranged from 14.87 to 98.73 percent (corrected for air contamination) for the Harlem coal bed and Clarion coal zone, respectively. Proportions of methane to the sum of the higher molecular weight hydrocarbons ranged from about 40 to 340 as the desorbed gas contained only a small percentage of higher weight hydrocarbons. Coalbed methane from the Upper Kittanning upper split and the Upper Kittanning coal beds is thermogenic in origin with isotopic composition of carbon (carbon 13, 13C) in methane (expressed as δ13C in units of parts per thousand (per mil) relative to the Vienna Peedee belemnite (VPDB) standard) ranging from -46.6 to -48.7 per mil. Coalbed methane from the Brush Creek and Upper Freeport coal beds and the Clarion coal zone contains some biogenic methane with δ13C values ranging from -51.05 to -51.56 per mil.

Provenance of Mesozoic clastic rocks within the Bangong-Nujiang suture zone, central Tibet: Implications for the age of the initial Lhasa-Qiangtang collision

NASA Astrophysics Data System (ADS)

Li, Shun; Guilmette, Carl; Ding, Lin; Xu, Qiang; Fu, Jia-Jun; Yue, Ya-Hui

2017-10-01

The Bangong-Nujiang suture zone, separating the Lhasa and Qiangtang blocks of the Tibetan Plateau, is marked by remnants of the Bangong-Nujiang oceanic basin. In the Gaize area of central Tibet, Mesozoic sedimentary strata recording the evolution of the basin and subsequent collision between these two blocks include the Upper Triassic-Lower Jurassic turbidites of the Mugagangri Group, the Upper Jurassic-Lower Cretaceous sandstone-dominated Wuga and Shamuluo formations, and the Upper Cretaceous molasse deposits of the Jingzhushan Formation. The Shamuluo and Jingzhushan formations rest unconformably on the underlying Mugagangri Group and Wuga Formation, respectively. In this contribution, we analyze petrographic components of sandstones and U-Pb-Hf isotopic compositions of detrital zircons from the Wuga and Jingzhushan formations for the first time. Based on the youngest detrital zircon ages, the maximum depositional ages of the Wuga and Jingzhushan formations are suggested to be ∼147-150 Ma and ∼79-91 Ma, respectively. Petrographic and isotopic results indicate that sediments in the Wuga Formation were mainly sourced from the accretionary complex (preserved as the Mugagangri Group) in the north, while sediments in the Jingzhushan Formation have mixed sources from the Lhasa block, the Qiangtang block and the intervening suture zone. Provenance analysis, together with regional data, suggests that the Upper Jurassic-Lower Cretaceous Wuga and Shamuluo formations were deposited in a peripheral foreland basin and a residual-sea basin, respectively, in response to the Lhasa-Qiangtang collision, whereas the Upper Cretaceous Jingzhushan Formation reflects continental molasse deposition during the post-collisional stage. The development of the peripheral foreland basin evidenced by deposition of the Wuga Formation reveals that the age of the initial Lhasa-Qiangtang collision might be the latest Jurassic (∼150 Ma).

76 FR 63202 - Security Zones; Captain of the Port Lake Michigan Zone

Federal Register 2010, 2011, 2012, 2013, 2014

2011-10-12

...-AA87 Security Zones; Captain of the Port Lake Michigan Zone AGENCY: Coast Guard, DHS. ACTION: Final rule. SUMMARY: Based on a review of safety and security zones around critical infrastructure in the... Chicago Harbor & Burnham Park Harbor--Safety and Security Zone regulation and the Security Zones; Captain...

Variations in Soil Properties and Herbicide Sorption Coefficients with Depth in Relation to PRZM (Pesticide Root Zone Model) Calculations

USDA-ARS?s Scientific Manuscript database

There are few experimental data available on how herbicide sorption coefficients change across small increments within soil profiles. Soil profiles were obtained from three landform elements (eroded upper slope, deposition zone, and eroded waterway) in a strongly eroded agricultural field and segmen...

76 FR 33639 - Safety Zone; New York Water Taxi 10th Anniversary Fireworks

Federal Register 2010, 2011, 2012, 2013, 2014

2011-06-09

...-AA00 Safety Zone; New York Water Taxi 10th Anniversary Fireworks, Upper New York Bay, Red Hook, NY... New York Water Taxi. The fireworks will commence at 9 p.m. on June 21, 2011 and will last... CFR Part 165 Harbors, Marine safety, Navigation (water), Reporting and recordkeeping requirements...

A review of the regional geophysics of the Arizona Transition Zone

NASA Technical Reports Server (NTRS)

Hendricks, J. D.; Plescia, J. B.

1991-01-01

A review of existing geophysical information and new data presented in this special section indicate that major changes in crustal properties between the Basin and Range and Colorado Plateau occur in, or directly adjacent to, the region defined as the Arizona Transition Zone. Although this region was designated on a physiographic basis, studies indicate that it is also the geophysical transition between adjoining provinces. The Transition Zone displays anomalous crustal and upper mantle seismic properties, shallow Curie isotherms, high heat flow, and steep down-to-the-plateau Bouguer gravity gradients. Seismic and gravity studies suggest that the change in crustal thickness, from thin crust in the Basin and Range to thick crust in the Colorado Plateau, may occur as a series of steps rather than a planar surface. Anomalous P wave velocities, high heat flow, shallow Curie isotherms, and results of gravity modeling suggest that the upper mantle is heterogeneous in this region. A relatively shallow asthenosphere beneath the Basin and Range and Transition Zone contrasted with a thick lithosphere beneath the Colorado Plateau would be one explanation that would satisfy these geophysical observations.

Geophysics applications in critical zone science: emerging topics

USDA-ARS?s Scientific Manuscript database

Geophysical studies have resulted in remarkable advances in characterization of critical zone. The geophysics applications uncover the relationships between structure and function in subsurface as they seek to define subsurface structural units with individual properties of retention and trans...

Collagen Fiber Orientation and Dispersion in the Upper Cervix of Non-Pregnant and Pregnant Women

PubMed Central

Myers, Kristin M.; Vink, Joy Y.; Wapner, Ronald J.; Hendon, Christine P.

2016-01-01

The structural integrity of the cervix in pregnancy is necessary for carrying a pregnancy until term, and the organization of human cervical tissue collagen likely plays an important role in the tissue’s structural function. Collagen fibers in the cervical extracellular matrix exhibit preferential directionality, and this collagen network ultrastructure is hypothesized to reorient and remodel during cervical softening and dilation at time of parturition. Within the cervix, the upper half is substantially loaded during pregnancy and is where the premature funneling starts to happen. To characterize the cervical collagen ultrastructure for the upper half of the human cervix, we imaged whole axial tissue slices from non-pregnant and pregnant women undergoing hysterectomy or cesarean hysterectomy respectively using optical coherence tomography (OCT) and implemented a pixel-wise fiber orientation tracking method to measure the distribution of fiber orientation. The collagen fiber orientation maps show that there are two radial zones and the preferential fiber direction is circumferential in a dominant outer radial zone. The OCT data also reveal that there are two anatomic regions with distinct fiber orientation and dispersion properties. These regions are labeled: Region 1—the posterior and anterior quadrants in the outer radial zone and Region 2—the left and right quadrants in the outer radial zone and all quadrants in the inner radial zone. When comparing samples from nulliparous vs multiparous women, no differences in these fiber properties were noted. Pregnant tissue samples exhibit an overall higher fiber dispersion and more heterogeneous fiber properties within the sample than non-pregnant tissue. Collectively, these OCT data suggest that collagen fiber dispersion and directionality may play a role in cervical remodeling during pregnancy, where distinct remodeling properties exist according to anatomical quadrant. PMID:27898677

Three-dimensional lithospheric electrical structure of Southern Granulite Terrain, India and its tectonic implications

NASA Astrophysics Data System (ADS)

Patro, Prasanta K.; Sarma, S. V. S.; Naganjaneyulu, K.

2014-01-01

crustal as well as the upper mantle lithospheric electrical structure of the Southern Granulite Terrain (SGT) is evaluated, using the magnetotelluric (MT) data from two parallel traverses: one is an 500 km long N-S trending traverse across SGT and another a 200 km long traverse. Data space Occam 3-D inversion was used to invert the MT data. The electrical characterization of lithospheric structure in SGT shows basically a highly resistive (several thousands of Ohm meters) upper crustal layer overlying a moderately resistive (a few hundred Ohm meters) lower crustal layer which in turn is underlain by the upper mantle lithosphere whose resistivity shows significant changes along the traverse. The highly resistive upper crustal layer is interspersed with four major conductive features with three of them cutting across the crustal column, bringing out a well-defined crustal block structure in SGT with individual highly resistive blocks showing correspondence to the geologically demarcated Salem, Madurai, and Trivandrum blocks. The 3-D model also brought out a well-defined major crustal conductor located in the northern half of the Madurai block. The electrical characteristics of this south dipping conductor and its close spatial correlation with two of the major structural elements, viz., Karur-Oddanchatram-Kodaikanal Shear Zone and Karur-Kamban-Painavu-Trichur Shear Zone, suggest that this conductive feature is closely linked to the subduction-collision tectonic processes in the SGT, and it is inferred that the Archean Dharwar craton/neoproterozoic SGT terrain boundary lies south of the Palghat-Cauvery shear zone. The results also showed that the Achankovil shear zone is characterized by a well-defined north dipping conductive feature. The resistive block adjoining this conductor on the southern side, representing the Trivandrum block, is shown to be downthrown along this north dipping crustal conductor relative to the Madurai block, suggesting a northward movement of Trivandrum block colliding against the Madurai block. The lithospheric upper mantle electrical structure of the SGT up to a depth of 100 km may be broadly divided into two distinctly different segments, viz., northern and southern segments. The northern lithospheric segment, over a major part, is characterized by a thick resistive upper mantle, while the southern one is characterized by a dominantly conductive medium suggesting a relatively thinned lithosphere in the southern segment.

Acoustic Observation of Living Organisms Reveals the Upper Limit of the Oxygen Minimum Zone

PubMed Central

Bertrand, Arnaud; Ballón, Michael; Chaigneau, Alexis

2010-01-01

Background Oxygen minimum zones (OMZs) are expanding in the World Ocean as a result of climate change and direct anthropogenic influence. OMZ expansion greatly affects biogeochemical processes and marine life, especially by constraining the vertical habitat of most marine organisms. Currently, monitoring the variability of the upper limit of the OMZs relies on time intensive sampling protocols, causing poor spatial resolution. Methodology/Principal Findings Using routine underwater acoustic observations of the vertical distribution of marine organisms, we propose a new method that allows determination of the upper limit of the OMZ with a high precision. Applied in the eastern South-Pacific, this original sampling technique provides high-resolution information on the depth of the upper OMZ allowing documentation of mesoscale and submesoscale features (e.g., eddies and filaments) that structure the upper ocean and the marine ecosystems. We also use this information to estimate the habitable volume for the world's most exploited fish, the Peruvian anchovy (Engraulis ringens). Conclusions/Significance This opportunistic method could be implemented on any vessel geared with multi-frequency echosounders to perform comprehensive high-resolution monitoring of the upper limit of the OMZ. Our approach is a novel way of studying the impact of physical processes on marine life and extracting valid information about the pelagic habitat and its spatial structure, a crucial aspect of Ecosystem-based Fisheries Management in the current context of climate change. PMID:20442791

Electrical resistivity structure beneath the Hangai Dome, Mongolia: intraplate volcanism and deformation imaged with magnetotelluric data

NASA Astrophysics Data System (ADS)

Comeau, M. J.; Becken, M.; Kaeufl, J.; Kuvshinov, A. V.; Kamm, J.; Grayver, A.; Demberel, S.; Usnikh, S. U.; Batmagnai, E.; Tserendug, S.

2017-12-01

The Hangai Dome in central Mongolia is characterized by intraplate volcanism on a high-elevation intra-continental plateau. Volcanism dates from the Oligocene to the Holocene and is thought to be coincident with the onset of the uplift of the Hangai Dome, indicating that the processes may be linked. However, the processes and driving mechanisms responsible for creating this region remain largely unexplained, due in part to a lack of high-resolution geophysical data over the area. An extensive magnetotelluric (MT) data set was collected over the Hangai Dome in 2016 and 2017, with broadband data (0.002 - 5,000 s) collected at a total of 294 sites. This data set consists of a large array ( 50 km site spacing) and several long ( 600 km) and dense ( 5 km site spacing) profiles that cross the uplifted Hangai Dome. Additionally, they cross the bounding faults of the Hangai block, the Bulnay fault in the north and the Bogd fault of the Gobi-Altai in the south, which have had several M>8 earthquakes in the past century. These MT data have been used to generate electrical resistivity models of the crust and upper mantle in this region. Anomalous, low resistivity ( 30 ohm-m) zones in the lower crust ( 25 - 50 km depth) are spatially associated with the surface expressions of volcanism and modern-day hydrothermal activity. These zones indicate the presence of local accumulations of fluids below the brittle-ductile transition zone. Interestingly, this feature terminates sharply at the South Hangai Fault Zone. Furthermore, lower resistivity pathways in the upper crust (0 - 25 km depth) connect the deeper features to the surface. This is prominently observed below the Hangai's youngest volcanic zones of Tariat/Khorgo and Chuluut, as well as the hot spring area of Tsenkher, near Tsetserleg. Additionally, an electrical signature can be associated with known fault zones and mineralized zones (such as the Bayankhongor mineral belt). An anomalous low-resistivity zone in the upper mantle ( 70 - 100 km) directly below the Hangai Dome can be explained by the presence of a small amount of partial melt. This zone likely represents the region of melt generation for intraplate volcanism and gives evidence for a small-scale (<100 km) asthenospheric upwelling, which contributes to intraplate deformation.

Plateau subduction, intraslab seismicity and the Denali Volcanic Gap

NASA Astrophysics Data System (ADS)

Bostock, M. G.; Chuang, L. Y.; Wech, A.; Plourde, A. P.

2017-12-01

Tectonic tremors in Alaska (USA) are associated with subduction of the Yakutat plateau, but their origins are unclear due to lack of depth constraints. We have processed tremor recordings to extract low-frequency earthquakes (LFEs), and generated a set of six LFE waveform templates via iterative network matched filtering and stacking. The timing of impulsive P (compressional) wave and S (shear) wave arrivals on template waveforms places LFEs at 40-58 km depth, near the upper envelope of intraslab seismicity and immediately updip of increased levels of intraslab seismicity. S waves at near-epicentral distances display polarities consistent with shear slip on the plate boundary. We compare characteristics of LFEs, seismicity, and tectonic structures in central Alaska with those in warm subduction zones, and propose a new model for the region's unusual intraslab seismicity and the enigmatic Denali volcanic gap (i.e., an area of no volcanism where expected). We argue that fluids in the Yakutat plate are confined to its upper crust, and that shallow subduction leads to hydromechanical conditions at the slab interface in central Alaska akin to those in warm subduction zones where similar LFEs and tremor occur. These conditions lead to fluid expulsion at shallow depths, explaining strike-parallel alignment of tremor occurrence with the Denali volcanic gap. Moreover, the lack of double seismic zone and restriction of deep intraslab seismicity to a persistent low-velocity zone are simple consequences of anhydrous conditions prevailing in the lower crust and upper mantle of the Yakutat plate.

Plateau subduction, intraslab seismicity, and the Denali (Alaska) volcanic gap

USGS Publications Warehouse

Chuang, Lindsay Yuling; Bostock, Michael; Wech, Aaron; Plourde, Alexandre

2018-01-01

Tectonic tremors in Alaska (USA) are associated with subduction of the Yakutat plateau, but their origins are unclear due to lack of depth constraints. We have processed tremor recordings to extract low-frequency earthquakes (LFEs), and generated a set of six LFE waveform templates via iterative network matched filtering and stacking. The timing of impulsive P (compressional) wave and S (shear) wave arrivals on template waveforms places LFEs at 40–58 km depth, near the upper envelope of intraslab seismicity and immediately updip of increased levels of intraslab seismicity. S waves at near-epicentral distances display polarities consistent with shear slip on the plate boundary. We compare characteristics of LFEs, seismicity, and tectonic structures in central Alaska with those in warm subduction zones, and propose a new model for the region’s unusual intraslab seismicity and the enigmatic Denali volcanic gap (i.e., an area of no volcanism where expected). We argue that fluids in the Yakutat plate are confined to its upper crust, and that shallow subduction leads to hydromechanical conditions at the slab interface in central Alaska akin to those in warm subduction zones where similar LFEs and tremor occur. These conditions lead to fluid expulsion at shallow depths, explaining strike-parallel alignment of tremor occurrence with the Denali volcanic gap. Moreover, the lack of double seismic zone and restriction of deep intraslab seismicity to a persistent low-velocity zone are simple consequences of anhydrous conditions prevailing in the lower crust and upper mantle of the Yakutat plate.

OZCAR: the French network of Critical Zone Observatories: principles and scientific objectives

NASA Astrophysics Data System (ADS)

Braud, Isabelle; Gaillardet, Jérôme; Hankard, Fatim; Le Borgne, Tanguy; Nord, Guillaume; Six, Delphine; Galy, Catherine; Laggoun-Défarge, Fatima; Tallec, Tiphaine; Pauwels, Hélène

2017-04-01

This contribution aims at presenting the principles that underlined the creation of the OZCAR research infrastructure, gathering various Critical Zone Observatories in France, and the scientific questions that drives the observation settings. The Critical Zone includes the fine zone between the lower atmosphere at the top of the canopy down to the bedrock-soil interface. This lithosphere-atmosphere boundary is critical for the availability of life-sustaining resources and critical for humanity because this is the zone where we live, where we build our cities, from which we extract our food and our water and where we release most of our wastes. This is the fragile zone on which the natural ecosystem relies because this is where nutrients are being released from the rocks. OZCAR is a distributed research infrastructure gathering instrumented sites and catchments on continental surfaces all dedicated to the observation and monitoring of the different compartments of the Critical Zone at the national scale. All these observatories (more that 40) were all built up on specific questions (acid deposition, flood prediction, urban hydrology…), some of them more than 50 years ago, but they have all in common to be highly instrumented, permanently funded as infrastructures. They all share the same overarching goal of understanding and predicting the Critical Zone in a changing world. OZCAR gathers instrumented catchments, hydrogeological sites, peatlands, glacier and permafrost regions and a spatial observatory under the common umbrella of understanding water and biogeochemical cycles and the associated fluxes of energy by using natural gradients and experimentation. Based on the collaboration with Southern Countries, OZCAR's sites have a global coverage including tropical areas and high mountainous regions in the Andes and the Himalaya. OZCAR benefits from a French investments project called CRITEX (Innovative equipment for the critical zone, https://www.critex.fr/critex-3/observatories/ ) that is centered on the development and deployment of innovative instrumentation in the sites. OZCAR was launched in 2016 under the leadership of the French Ministry in charge of Higher Education and Research, assembling all French Research Institutions involved in environmental studies and with the ambition of facilitating interdisciplinary research in terrestrial surfaces, stimulating instrumental development and being visible at the international level. The paper will presents the main common scientific questions, challenges in terms of instrumentation and experimentation deployment, in particular in terms of co-location of sites, data base and modelling activities that the OZCAR network plan to address in the next years.

Does model structure limit the use of satellite data as hydrologic forcing for distributed operational models?

NASA Astrophysics Data System (ADS)

Bowman, A. L.; Franz, K.; Hogue, T. S.

2015-12-01

We are investigating the implications for use of satellite data in operational streamflow prediction. Specifically, the consequence of potential hydrologic model structure deficiencies on the ability to achieve improved forecast accuracy through the use of satellite data. We want to understand why advanced data do not lead to improved streamflow simulations by exploring how various fluxes and states differ among models of increasing complexity. In a series of prior studies, we investigated the use of a daily satellite-derived potential evapotranspiration (PET) estimate as input to the National Weather Service (NWS) streamflow forecast models for watersheds in the Upper Mississippi and Red river basins. Although the spatial PET product appears to represent the day-to-day variability in PET more realistically than current climatological methods used by the NWS, the impact of the satellite data on streamflow simulations results in slightly poorer model efficiency overall. Analysis of the model states indicates the model progresses differently between simulations with baseline PET and the satellite-derived PET input, though variation in streamflow simulations overall is negligible. For instance, the upper zone states, responsible for the high flows of a hydrograph, show a profound difference, while simulation of the peak flows tend to show little variation in the timing and magnitude. Using the spatial PET input, the lower zone states show improvement with simulating the recession limb and baseflow portion of the hydrograph. We anticipate that through a better understanding of the relationship between model structure, model states, and simulated streamflow we will be able to diagnose why simulations of discharge from the forecast model have failed to improve when provided seemingly more representative input data. Identifying model limitations are critical to demonstrating the full benefit of a satellite data for operational use.

State of stress and crustal fluid migration related to west-dipping structures in the slab-forearc system in the northern Chilean subduction zone

NASA Astrophysics Data System (ADS)

Salazar, P.; Kummerow, J.; Wigger, P.; Shapiro, S.; Asch, G.

2017-03-01

Previous studies in the forearc of the northern Chilean subduction zone have identified important tectonic features in the upper crust. As a result of these works, the West Fissure Fault System (WFFS) has recently been imaged using microseismic events. The WFFS is the westward-dipping, sharp lower boundary of the northern Chilean forearc and is geometrically opposed to subduction of the Nazca plate. The present article builds on this previous work and is novel in that it characterizes this structure's stress distribution using focal mechanisms and stress tensor analysis. The results of the stress tensor analysis show that the state of stress in the WFFS is related to its strike-slip tectonic context and likely represents a manifestation of local forces associated with the highest areas in the Andes. Two seismic clusters have also been identified; these clusters may be associated with a blind branch of the WFFS. We studied these clusters in order to determine their sources and possible connection with fluid migration across the upper plate. We observed that the two clusters differ from one another in some regards. The central cluster has characteristics consistent with an earthquake swarm with two clearly identifiable phases. Conversely, the SW cluster has a clear main shock associated with it, and it can be separated into two subclusters (A and A΄). In contrast, similarities among the two clusters suggest that the clusters may have a common origin. The b-values for both clusters are characteristic of tectonic plate boundaries. The spatial spreading, which is approximately confined to one plane, reflects progressive growth of the main fracture underlying the swarm and subcluster A. We also find that earthquakes themselves trigger aftershocks near the borders of their rupture areas. In addition, the spatio-temporal migration of hypocentres, as well as their spatial correlation with areas that are interpreted to be fluid migration zones, suggest that there is a close relationship between fluid movement and the earthquake sources associated with the swarm and subcluster A. These observations point to stick-slip behaviour of the rupture propagation, which can be explained by earthquake-induced stress transfer and fluid flow in a fluid-permeated, critically loaded fault zone.

Models of Deformation of Uppermost Oceanic Lithosphere: Comparison of Crustal Flexure in the Blönduós Area, Northern Iceland, and Structure of East Pacific Rise Crust at Hess Deep

NASA Astrophysics Data System (ADS)

Horst, A. J.; Karson, J. A.; Varga, R. J.; Gee, J. S.

2007-12-01

Models of the internal structure of oceanic crust have been constructed from studies of ophiolites and from more recent observations of tectonic windows into the upper crust. Spreading rate and/or magma supply are the central variables that control ridge processes and the ultimate architecture of ocean crust. In addition to ophiolites, Iceland also provides an important analog to study mid-ocean ridge processes and structure. Flexure zones in Iceland characterize the structure of Tertiary-Recent lava flows, and are areas wherein lavas dip regionally inward toward the axis of one of several ~N/S-trending rift zones. These rift zones are interpreted to represent fossil spreading centers which were abandoned during a series of eastward-directed ridge jumps. In the Hildará area, north-central Iceland, the eastern side of a regional flexure is characterized by westward-dipping lavas, approximately 6-8 Ma, which are cut by east-dipping normal faults and dikes. The upper-crustal structure within this flexure zone from slow spread (~20 mm/yr) crust exhibits remarkable similarities to the structure of the upper crust created at a fast-spreading (110 mm/yr) segment of the East Pacific Rise (EPR) observed at Hess Deep. In this modern ocean setting, ~1 Ma crust is characterized by west-dipping lavas above consistently east-dipping (away from the EPR) dikes and dike-subparallel fault zones. In both locations, paleomagnetic and structural data indicate that west-dipping lavas and east-dipping dikes result from tectonic rotations. In addition, cross-cutting dike relationships demonstrate that dike intrusion occurred both during and after normal fault- related tilting. These data indicate that fault-controlled tilting was initiated within the narrow neovolcanic zone of the ridge and is not associated with off-axis processes. Lavas at magmatically robust ridges commonly flow away from elevated ridge-crests. Measurement of anisotropy of magnetic susceptibility (AMS) of the lavas from the flexure in Iceland suggests a mean flow direction to the northeast, that is, away from the fossil-ridge axis, demonstrating that the fossil spreading center from which the lavas were extruded was located to the west. Despite the distinct differences in spreading rates, the high magma supply in both environments resulted in a very similar upper crustal architecture.

Palaeozoic and Mesozoic tectonic implications of Central Afghanistan

NASA Astrophysics Data System (ADS)

Sliaupa, Saulius; Motuza, Gediminas

2017-04-01

The field and laboratory studies were carried out in Ghor Province situated in the central part of Afghanistan. It straddles juxtaposition of the Tajik (alternatively, North Afghanistan) and Farah Rod blocks separated by Band-e-Bayan zone. The recent studies indicate that Band-e-Bayan zone represents highly tectonised margin of the Tajik block (Motuza, Sliaupa, 2016). The Band-e-Bayan zone is the most representative in terms of sedimentary record. The subsidence trends and sediment lithologies suggest the passive margin setting during (Cambrian?) Ordovician to earliest Carboniferous times. A change to the foredeep setting is implied in middle Carboniferous through Early Permian; the large-thickness flysh-type sediments were derived from continental island arc provenance, as suggested by chemical composition of mudtstones. This stage can be correlated to the amalgamation of the Gondwana supercontinent. The new passive-margin stage can be inferred in the Band-e-Bayan zone and Tajik blocks in the Late Permian throughout the early Late Triassic that is likely related to breaking apart of Gondwana continent. A collisional event is suggested in latest Triassic, as seen in high-rate subsidence associating with dramatic change in litholgies, occurrence of volcanic rocks and granidoid intrusions. The continental volcanic island arc derived (based on geochemical indices) terrigens prevail at the base of Jurassic that were gradually replaced by carbonate platform in the Middle Jurassic pointing to cessation of the tectonic activity. A new tectonic episode (no deposition; and folding?) took place in the Tajik and Band-e-Bayan zone in Late Jurassic. The geological section of the Farah Rod block, situated to the south, is represented by Jurassic and Cretaceous sediments overlain by sporadic Cenozoic volcanic-sedimentary succession. The lower part of the Mesozoic succession is composed of terrigenic sediments giving way to upper Lower Cretaceous shallow water carbonates implying low tectonic regime. There was a break in sedimentation during the upper Cretaceous that is likely related to the Alpine orogenic event. It associated with some Upper Cretaceous magmatic activity (Debon et al., 1987). This event is reflected in the sedimentation pattern in the adjacent Band-e-Bayan zone and Tadjick block. The lower part of the Upper Cretaceous succession is composed of reddish terrigenic sediments. They are overlain by uppermost Cretaceous (and Danian) shallow marine sediments implying establishment of quiet tectonic conditions.

Dissolved organic carbon concentrations and compositions, and trihalomethane formation potentials in waters from agricultural peat soils, Sacramento-San Joaquin Delta, California; implications for drinking-water quality

USGS Publications Warehouse

Fujii, Roger; Ranalli, Anthony J.; Aiken, George R.; Bergamaschi, Brian A.

1998-01-01

Water exported from the Sacramento-San Joaquin River delta (Delta) is an important drinking-water source for more than 20 million people in California. At times, this water contains elevated concentrations of dissolved organic carbon and bromide, and exceeds the U.S. Environmental Protection Agency's maximum contaminant level for trihalomethanes of 0.100 milligrams per liter if chlorinated for drinking water. About 20 to 50 percent of the trihalomethane precursors to Delta waters originates from drainage water from peat soils on Delta islands. This report elucidates some of the factors and processes controlling and affecting the concentration and quality of dissolved organic carbon released from peat soils and relates the propensity of dissolved organic carbon to form trihalomethanes to its chemical composition.Soil water was sampled from near-surface, oxidized, well-decomposed peat soil (upper soil zone) and deeper, reduced, fibrous peat soil (lower soil zone) from one agricultural field in the west central Delta over 1 year. Concentrations of dissolved organic carbon in the upper soil zone were highly variable, with median concentrations ranging from 46.4 to 83.2 milligrams per liter. Concentrations of dissolved organic carbon in samples from the lower soil zone were much less variable and generally slightly higher than samples from the upper soil zone, with median concentrations ranging from 49.3 to 82.3 milligrams per liter. The dissolved organic carbon from the lower soil zone had significantly higher aromaticity (as measured by specific ultraviolet absorbance) and contained significantly greater amounts of aromatic humic substances (as measured by XAD resin fractionation and carbon-13 nuclear magnetic resonance analysis of XAD isolates) than the dissolved organic carbon from the upper soil zone. These results support the conclusion that more aromatic forms of dissolved organic carbon are produced under anaerobic conditions compared to aerobic conditions. Dissolved organic carbon concentration, trihalomethane formation potential, and ultraviolet absorbance were all highly correlated, showing that trihalomethane precursors increased with increasing dissolved organic carbon and ultraviolet absorbance for whole water samples. Contrary to the generally accepted conceptual model for trihalomethane formation that assumes that aromatic forms of carbon are primary precursors to trihalomethanes, results from this study indicate that dissolved organic carbon aromaticity appears unrelated to trihalomethane formation on a carbon-normalized basis. Thus, dissolved organic carbon aromaticity alone cannot fully explain or predict trihalomethane precursor content, and further investigation of aromatic and nonaromatic forms of carbon will be needed to better identify trihalomethane precursors.

Late Cretaceous base level lowering in Campanian and Maastrichtian depositional sequences, Kure Beach, North Carolina

USGS Publications Warehouse

Harris, W.B.; ,

2006-01-01

Campanian through Maastrichtian mixed carbonate and siliciclastic sediments in a 422 m continuous core drilled at Kure Beach, NC provide a record of sea-level change. Based on lithology and stratigraphy, depositional sequences are defined, and calcareous nannofossil zones and 87Sr/86Sr ratios and corresponding ages using the LOWESS Table determined. Campanian and Maastrichtian sediments comprise six depositional sequences. The oldest is Tar Heel 1 and contains calcareous nannofossils that indicate assignment to the upper part of Zones CC18a, CC18c and the lower part of CC19. 87Sr/86 Sr ratios indicate ages from 83.2 to 80.0 Ma or lower Campanian. Tar Heel II contains calcareous nannofossils that indicate assignment to the upper part of Zone CC 19 and CC20. 87Sr/86Sr ratios indicate ages from 78.0 to 76.3 Ma or middle Campanian. Donoho Creek I and II are thin and contain calcareous nannofossils referable to upper Zone CC21 and Zone CC22, and to CC23, respectively. The top of Donoho Creek II marks the Campanian-Maastrichtian boundary. Donoho Creek I 87Sr/86Sr ratios cluster into two groups, and provide ages from 78.0 to 76.2 Ma and 73.7 to 72.3 Ma, respectively. 87Sr/86Sr ratios in Donoho Creek II indicate ages from 71.4 to 69.6 Ma. Two Maastrichtian sequences are present; the lowermost Peedee I contains calcareous nannofossils that place it in Zones CC25a and CC25b. 87Sr/86Sr r ratios indicate an age from 69.3 to 66.9 Ma or late Maastrichtian. Peedee II is assigned to calcareous nannofossil Zone CC26a. 87Sr/86Sr ratios indicate ages from 66.4 to 65.2 Ma or late Maastrichtian. The four Campanian sequences correlate to three depositional sequences in New Jersey; the sequence boundary between upper Campanian Donoho Creek I and Donoho Creek II is not recognized in New Jersey. This boundary is interpreted to result from Gulf Stream impingement and subsequent erosion on the outer shelf. The two Maastrichtian sequences recognized in the Kure Beach core correlate to the two identified Maastrichtian sequences in New Jersey. These data support base-level lowering of sea-level during the Campanian-Maastrichtian, and suggest that the western margin of the North Atlantic may contain one of the best Late Cretaceous records of sea-level change.

Tri-critical behavior of the Blume-Emery-Griffiths model on a Kagomé lattice: Effective-field theory and Rigorous bounds

NASA Astrophysics Data System (ADS)

Santos, Jander P.; Sá Barreto, F. C.

2016-01-01

Spin correlation identities for the Blume-Emery-Griffiths model on Kagomé lattice are derived and combined with rigorous correlation inequalities lead to upper bounds on the critical temperature. From the spin correlation identities the mean field approximation and the effective field approximation results for the magnetization, the critical frontiers and the tricritical points are obtained. The rigorous upper bounds on the critical temperature improve over those effective-field type theories results.

Experimental study on the heat transfer characteristics of waste printed circuit boards pyrolysis.

PubMed

Ma, Hongting; Du, Na; Lin, Xueyin; Li, Chen; Lai, Junwen; Li, Zihao

2018-08-15

In order to study the appropriate and advanced technology for recycling waste printed circuit boards (PCBs), a fixed bed pyrolysis device with stirring function has been designed and developed. The effect of rotating speed on the temperature distribution and mass change in the pyrolysis process of FR-4 PCB has been analyzed. The heat transfer and pyrolysis characteristics of different granular layers with and without stirring have been investigated. The results indicate that the stirring can change the main way of heat transfer from conduction to convection in the PCB layers. As the increase of rotating speed, the temperature rising rate of material at the bottom of the pyrolysis furnace gradually decreases, while the heating rate is increasing at the upper layer, and the temperature difference between the upper and bottom layers is gradually reduced. When the rotating speed varies from 0r/min to 18r/min, the weight loss of the material increases from 3.97% to 6.76%, and the overall pyrolysis degree is improved. During the pyrolysis process, the material layer can be divided into three zones along the vertical direction, namely complete pyrolysis zone, partial pyrolysis zone and non-pyrolysis zone. As the rotating speed is 0r/min, the thickness of each zones is 6cm, 6cm and 3cm, respectively. However, when the rotating speed is increased to 18r/min, the non-pyrolysis zone disappears, and the thickness of complete pyrolysis zone and partial pyrolysis zone increase to 9cm and 6cm, respectively. Copyright © 2018 Elsevier B.V. All rights reserved.

The north-subducting Rheic Ocean during the Devonian: consequences for the Rhenohercynian ore sites

NASA Astrophysics Data System (ADS)

von Raumer, Jürgen F.; Nesbor, Heinz-Dieter; Stampfli, Gérard M.

2017-10-01

Base metal mining in the Rhenohercynian Zone has a long history. Middle-Upper Devonian to Lower Carboniferous sediment-hosted massive sulfide deposits (SHMS), volcanic-hosted massive sulfide deposits (VHMS) and Lahn-Dill-type iron, and base metal ores occur at several sites in the Rhenohercynian Zone that stretches from the South Portuguese Zone, through the Lizard area, the Rhenish Massif and the Harz Mountain to the Moravo-Silesian Zone of SW Bohemia. During Devonian to Early Carboniferous times, the Rhenohercynian Zone is seen as an evolving rift system developed on subsiding shelf areas of the Old Red continent. A reappraisal of the geotectonic setting of these ore deposits is proposed. The Middle-Upper Devonian to Early Carboniferous time period was characterized by detrital sedimentation, continental intraplate and subduction-related volcanism. The large shelf of the Devonian Old Red continent was the place of thermal subsidence with contemporaneous mobilization of rising thermal fluids along activated Early Devonian growth faults. Hydrothermal brines equilibrated with the basement and overlying Middle-Upper Devonian detrital deposits forming the SHMS deposits in the southern part of the Pyrite Belt, in the Rhenish Massif and in the Harz areas. Volcanic-hosted massive sulfide deposits (VHMS) formed in the more eastern localities of the Rhenohercynian domain. In contrast, since the Tournaisian period of ore formation, dominant pull-apart triggered magmatic emplacement of acidic rocks, and their metasomatic replacement in the apical zones of felsic domes and sediments in the northern part of the Iberian Pyrite belt, thus changing the general conditions of ore precipitation. This two-step evolution is thought to be controlled by syn- to post-tectonic phases in the Variscan framework, specifically by the transition of geotectonic setting dominated by crustal extension to a one characterized by the subduction of the supposed northern slab of the Rheic Ocean preceding the general Late Variscan crustal shortening and oroclinal bending.

Ambient noise tomography reveals upper crustal structure of Icelandic rifts

NASA Astrophysics Data System (ADS)

Green, Robert G.; Priestley, Keith F.; White, Robert S.

2017-05-01

The structure of oceanic spreading centres and subsurface melt distribution within newly formed crust is largely understood from marine seismic experiments. In Iceland, however, sub-aerial rift elevation allows both accurate surface mapping and the installation of large broadband seismic arrays. We present a study using ambient noise Rayleigh wave tomography to image the volcanic spreading centres across Iceland. Our high resolution model images a continuous band of low seismic velocities, parallelling all three segments of the branched rift in Iceland. The upper 10 km contains strong velocity variations, with shear wave velocities 0.5 km s-1 faster in the older non-volcanically active regions compared to the active rifts. Slow velocities correlate very closely with geological surface mapping, with contours of the anomalies parallelling the edges of the neo-volcanic zones. The low-velocity band extends to the full 50 km width of the neo-volcanic zones, demonstrating a significant contrast with the narrow (8 km wide) magmatic zone seen at fast spreading ridges, where the rate of melt supply is similarly high. Within the seismically slow rift band, the lowest velocity cores of the anomalies occur above the centre of the mantle plume under the Vatnajökull icecap, and in the Eastern Volcanic Zone under the central volcano Katla. This suggests localisation of melt accumulation at these specific volcanic centres, demonstrating variability in melt supply into the shallow crust along the rift axis. Shear velocity inversions with depth show that the strongest velocity contrasts are found in the upper 8 km, and show a slight depression in the shear velocity through the mid crust (10-20 km) in the rifts. Our model also shows less intensity to the slow rift anomaly in the Western Volcanic Zone, supporting the notion that rift activity here is decreasing as the ridge jumps to the Eastern Volcanic Zone.

Microbial eukaryote diversity in the marine oxygen minimum zone off northern Chile.

PubMed

Parris, Darren J; Ganesh, Sangita; Edgcomb, Virginia P; DeLong, Edward F; Stewart, Frank J

2014-01-01

Molecular surveys are revealing diverse eukaryotic assemblages in oxygen-limited ocean waters. These communities may play pivotal ecological roles through autotrophy, feeding, and a wide range of symbiotic associations with prokaryotes. We used 18S rRNA gene sequencing to provide the first snapshot of pelagic microeukaryotic community structure in two cellular size fractions (0.2-1.6 μm, >1.6 μm) from seven depths through the anoxic oxygen minimum zone (OMZ) off northern Chile. Sequencing of >154,000 amplicons revealed contrasting patterns of phylogenetic diversity across size fractions and depths. Protist and total eukaryote diversity in the >1.6 μm fraction peaked at the chlorophyll maximum in the upper photic zone before declining by ~50% in the OMZ. In contrast, diversity in the 0.2-1.6 μm fraction, though also elevated in the upper photic zone, increased four-fold from the lower oxycline to a maximum at the anoxic OMZ core. Dinoflagellates of the Dinophyceae and endosymbiotic Syndiniales clades dominated the protist assemblage at all depths (~40-70% of sequences). Other protist groups varied with depth, with the anoxic zone community of the larger size fraction enriched in euglenozoan flagellates and acantharean radiolarians (up to 18 and 40% of all sequences, respectively). The OMZ 0.2-1.6 μm fraction was dominated (11-99%) by Syndiniales, which exhibited depth-specific variation in composition and total richness despite uniform oxygen conditions. Metazoan sequences, though confined primarily to the 1.6 μm fraction above the OMZ, were also detected within the anoxic zone where groups such as copepods increased in abundance relative to the oxycline and upper OMZ. These data, compared to those from other low-oxygen sites, reveal variation in OMZ microeukaryote composition, helping to identify clades with potential adaptations to oxygen-depletion.

Microbial eukaryote diversity in the marine oxygen minimum zone off northern Chile

PubMed Central

Parris, Darren J.; Ganesh, Sangita; Edgcomb, Virginia P.; DeLong, Edward F.; Stewart, Frank J.

2014-01-01

Molecular surveys are revealing diverse eukaryotic assemblages in oxygen-limited ocean waters. These communities may play pivotal ecological roles through autotrophy, feeding, and a wide range of symbiotic associations with prokaryotes. We used 18S rRNA gene sequencing to provide the first snapshot of pelagic microeukaryotic community structure in two cellular size fractions (0.2–1.6 μm, >1.6 μm) from seven depths through the anoxic oxygen minimum zone (OMZ) off northern Chile. Sequencing of >154,000 amplicons revealed contrasting patterns of phylogenetic diversity across size fractions and depths. Protist and total eukaryote diversity in the >1.6 μm fraction peaked at the chlorophyll maximum in the upper photic zone before declining by ~50% in the OMZ. In contrast, diversity in the 0.2–1.6 μm fraction, though also elevated in the upper photic zone, increased four-fold from the lower oxycline to a maximum at the anoxic OMZ core. Dinoflagellates of the Dinophyceae and endosymbiotic Syndiniales clades dominated the protist assemblage at all depths (~40–70% of sequences). Other protist groups varied with depth, with the anoxic zone community of the larger size fraction enriched in euglenozoan flagellates and acantharean radiolarians (up to 18 and 40% of all sequences, respectively). The OMZ 0.2–1.6 μm fraction was dominated (11–99%) by Syndiniales, which exhibited depth-specific variation in composition and total richness despite uniform oxygen conditions. Metazoan sequences, though confined primarily to the 1.6 μm fraction above the OMZ, were also detected within the anoxic zone where groups such as copepods increased in abundance relative to the oxycline and upper OMZ. These data, compared to those from other low-oxygen sites, reveal variation in OMZ microeukaryote composition, helping to identify clades with potential adaptations to oxygen-depletion. PMID:25389417

Seismic reflection imaging of two megathrust shear zones in the northern Cascadia subduction zone.

PubMed

Calvert, Andrew J

2004-03-11

At convergent continental margins, the relative motion between the subducting oceanic plate and the overriding continent is usually accommodated by movement along a single, thin interface known as a megathrust. Great thrust earthquakes occur on the shallow part of this interface where the two plates are locked together. Earthquakes of lower magnitude occur within the underlying oceanic plate, and have been linked to geochemical dehydration reactions caused by the plate's descent. Here I present deep seismic reflection data from the northern Cascadia subduction zone that show that the inter-plate boundary is up to 16 km thick and comprises two megathrust shear zones that bound a >5-km-thick, approximately 110-km-wide region of imbricated crustal rocks. Earthquakes within the subducting plate occur predominantly in two geographic bands where the dip of the plate is inferred to increase as it is forced around the edges of the imbricated inter-plate boundary zone. This implies that seismicity in the subducting slab is controlled primarily by deformation in the upper part of the plate. Slip on the shallower megathrust shear zone, which may occur by aseismic slow slip, will transport crustal rocks into the upper mantle above the subducting oceanic plate and may, in part, provide an explanation for the unusually low seismic wave speeds that are observed there.

Marine forearc extension in the Hikurangi Margin: New insights from high-resolution 3D seismic data

NASA Astrophysics Data System (ADS)

Böttner, Christoph; Gross, Felix; Geersen, Jacob; Mountjoy, Joshu; Crutchley, Gareth; Krastel, Sebastian

2017-04-01

In subduction zones upper-plate normal faults have long been considered a tectonic feature primarily associated with erosive margins. However, increasing data coverage has proven that similar features also occur in accretionary margins, such as Cascadia, Makran, Nankai or Central Chile, where kinematics are dominated by compression. Considering their wide distribution there is, without doubt, a significant lack of qualitative and quantitative knowledge regarding the role and importance of normal faults and zones of extension for the seismotectonic evolution of accretionary margins. We use a high-resolution 3D P-Cable seismic volume from the Hikurangi Margin acquired in 2014 to analyze the spatial distribution and mechanisms of upper-plate normal faulting. The study area is located at the upper continental slope in the area of the Tuaheni landslide complex. In detail we aim to (1) map the spatial distribution of normal faults and characterize their vertical throws, strike directions, and dip angles; (2) investigate their possible influence on fluid migration in an area, where gas hydrates are present; (3) discuss the mechanisms that may cause extension of the upper-slope in the study area. Beneath the Tuaheni Landslide Complex we mapped about 200 normal faults. All faults have low displacements (<15 m) and dip at high (> 65°) angles. About 71% of the faults dip landward. We found two main strike directions, with the majority of faults striking 350-10°, parallel to the deformation front. A second group of faults strikes 40-60°. The faults crosscut the BSR, which indicates the base of the gas hydrate zone. In combination with seismically imaged bright-spots and pull-up structures, this indicates that the normal faults effectively transport fluids vertically across the base of the gas hydrate zone. Localized uplift, as indicated by the presence of the Tuaheni Ridge, might support normal faulting in the study area. In addition, different subduction rates across the margin may also favor extension between the segments. Future work will help to further untangle the mechanisms that cause extension of the upper continental slope.

Geologic framework and hydrostratigraphy of the Edwards and Trinity aquifers within northern Bexar and Comal Counties, Texas

USGS Publications Warehouse

Clark, Allan K.; Golab, James A.; Morris, Robert R.

2016-11-28

During 2014–16, the U.S. Geological Survey, in cooperation with the Edwards Aquifer Authority, documented the geologic framework and hydrostratigraphy of the Edwards and Trinity aquifers within northern Bexar and Comal Counties, Texas. The Edwards and Trinity aquifers are major sources of water for agriculture, industry, and urban and rural communities in south-central Texas. Both the Edwards and Trinity are classified as major aquifers by the State of Texas.The purpose of this report is to present the geologic framework and hydrostratigraphy of the Edwards and Trinity aquifers within northern Bexar and Comal Counties, Tex. The report includes a detailed 1:24,000-scale hydrostratigraphic map, names, and descriptions of the geology and hydrostratigraphic units (HSUs) in the study area.The scope of the report is focused on geologic framework and hydrostratigraphy of the outcrops and hydrostratigraphy of the Edwards and Trinity aquifers within northern Bexar and Comal Counties, Tex. In addition, parts of the adjacent upper confining unit to the Edwards aquifer are included.The study area, approximately 866 square miles, is within the outcrops of the Edwards and Trinity aquifers and overlying confining units (Washita, Eagle Ford, Austin, and Taylor Groups) in northern Bexar and Comal Counties, Tex. The rocks within the study area are sedimentary and range in age from Early to Late Cretaceous. The Miocene-age Balcones fault zone is the primary structural feature within the study area. The fault zone is an extensional system of faults that generally trends southwest to northeast in south-central Texas. The faults have normal throw, are en echelon, and are mostly downthrown to the southeast.The Early Cretaceous Edwards Group rocks were deposited in an open marine to supratidal flats environment during two marine transgressions. The Edwards Group is composed of the Kainer and Person Formations. Following tectonic uplift, subaerial exposure, and erosion near the end of Early Cretaceous time, the area of present-day south-central Texas was again submerged during the Late Cretaceous by a marine transgression resulting in deposition of the Georgetown Formation of the Washita Group.The Early Cretaceous Edwards Group, which overlies the Trinity Group, is composed of mudstone to boundstone, dolomitic limestone, argillaceous limestone, evaporite, shale, and chert. The Kainer Formation is subdivided into (bottom to top) the basal nodular, dolomitic, Kirschberg Evaporite, and grainstone members. The Person Formation is subdivided into (bottom to top) the regional dense, leached and collapsed (undivided), and cyclic and marine (undivided) members.Hydrostratigraphically the rocks exposed in the study area represent a section of the upper confining unit to the Edwards aquifer, the Edwards aquifer, the upper zone of the Trinity aquifer, and the middle zone of the Trinity aquifer. The Pecan Gap Formation (Taylor Group), Austin Group, Eagle Ford Group, Buda Limestone, and Del Rio Clay are generally considered to be the upper confining unit to the Edwards aquifer.The Edwards aquifer was subdivided into HSUs I to VIII. The Georgetown Formation of the Washita Group contains HSU I. The Person Formation of the Edwards Group contains HSUs II (cyclic and marine members [Kpcm], undivided), III (leached and collapsed members [Kplc,] undivided), and IV (regional dense member [Kprd]), and the Kainer Formation of the Edwards Group contains HSUs V (grainstone member [Kkg]), VI (Kirschberg Evaporite Member [Kkke]), VII (dolomitic member [Kkd]), and VIII (basal nodular member [Kkbn]).The Trinity aquifer is separated into upper, middle, and lower aquifer units (hereinafter referred to as “zones”). The upper zone of the Trinity aquifer is in the upper member of the Glen Rose Limestone. The middle zone of the Trinity aquifer is formed in the lower member of the Glen Rose Limestone, Hensell Sand, and Cow Creek Limestone. The regionally extensive Hammett Shale forms a confining unit between the middle and lower zones of the Trinity aquifer. The lower zone of the Trinity aquifer consists of the Sligo and Hosston Formations, which do not crop out in the study area.The upper zone of the Trinity aquifer is subdivided into five informal HSUs (top to bottom): cavernous, Camp Bullis, upper evaporite, fossiliferous, and lower evaporite. The middle zone of the Trinity aquifer is composed of the (top to bottom) Bulverde, Little Blanco, Twin Sisters, Doeppenschmidt, Rust, Honey Creek, Hensell, and Cow Creek HSUs. The underlying Hammett HSU is a regional confining unit between the middle and lower zones of the Trinity aquifer. The lower zone of the Trinity aquifer is not exposed in the study area.Groundwater recharge and flow paths in the study area are influenced not only by the hydrostratigraphic characteristics of the individual HSUs but also by faults and fractures and geologic structure. Faulting associated with the Balcones fault zone (1) might affect groundwater flow paths by forming a barrier to flow that results in water moving parallel to the fault plane, (2) might affect groundwater flow paths by increasing flow across the fault because of fracturing and juxtaposing porous and permeable units, or (3) might have no effect on the groundwater flow paths.The hydrologic connection between the Edwards and Trinity aquifers and the various HSUs is complex. The complexity of the aquifer system is a combination of the original depositional history, bioturbation, primary and secondary porosity, diagenesis, and fracturing of the area from faulting. All of these factors have resulted in development of modified porosity, permeability, and transmissivity within and between the aquifers. Faulting produced highly fractured areas that have allowed for rapid infiltration of water and subsequently formed solutionally enhanced fractures, bedding planes, channels, and caves that are highly permeable and transmissive. The juxtaposition resulting from faulting has resulted in areas of interconnectedness between the Edwards and Trinity aquifers and the various HSUs that form the aquifers.

Upper crustal densities derived from sea floor gravity measurements: Northern Juan De Fuca Ridge

USGS Publications Warehouse

Holmes, Mark L.; Johnson, H. Paul

1993-01-01

A transect of sea floor gravity stations has been analyzed to determine upper crustal densities on the Endeavour segment of the northern Juan de Fuca Ridge. Data were obtained using ALVIN along a corridor perpendicular to the axis of spreading, over crustal ages from 0 to 800,000 years. Calculated elevation factors from the gravity data show an abrupt increase in density with age (distance) for the upper 200 m of crust. This density change is interpreted as a systematic reduction in bulk porosity of the upper crustal section, from 23% for the axial ridge to 10% for the off-axis flanking ridges. The porosity decrease is attributed to the collapse and filling of large-scale voids as the abyssal hills move out of the crustal formation zone. Forward modeling of a plausible density structure for the near-axis region agrees with the observed anomaly data only if the model includes narrow, along-strike, low-density regions adjacent to both inner and outer flanks of the abyssal hills. The required low density zones could be regions of systematic upper crustal fracturing and faulting that were mapped by submersible observers and side-scan sonar images, and whose presence was suggested by the distribution of heat flow data in the same area.

Revised hydrogeologic framework of the Floridan aquifer system in the northern coastal area of Georgia and adjacent parts of South Carolina

USGS Publications Warehouse

Williams, Lester J.; Gill, Harold E.

2010-01-01

The hydrogeologic framework for the Floridan aquifer system has been revised for eight northern coastal counties in Georgia and five coastal counties in South Carolina by incorporating new borehole geophysical and flowmeter log data collected during previous investigations. Selected well logs were compiled and analyzed to determine the vertical and horizontal continuity of permeable zones that make up the Upper and Lower Floridan aquifers and to define more precisely the thickness of confining beds that separate these aquifers. The updated framework generally conforms to the original framework established by the U.S. Geological Survey in the 1980s except for adjustments made to the internal boundaries of the Upper and Lower Floridan aquifers and the individual permeable zones that compose these aquifers. The revised boundaries of the Floridan aquifer system were mapped by taking into account results from local studies and regional correlations of geologic and hydrogeologic units. Because the revised framework does not match the previous regional framework along all edges, additional work will be needed to expand the framework into adjacent areas. The Floridan aquifer system in the northern coastal region of Georgia and parts of South Carolina can be divided into the Upper and Lower Floridan aquifers, which are separated by a middle confining unit of relatively lower permeability. The Upper Floridan aquifer includes permeable and hydraulically connected carbonate rocks of Oligocene and upper Eocene age that represent the most transmissive part of the aquifer system. The middle confining unit consists of low permeability carbonate rocks that lie within the lower part of the upper Eocene in Beaufort and Jasper Counties, South Carolina, and within the upper to middle parts of the middle Eocene elsewhere. Locally, the middle confining unit contains thin zones that have moderate to high permeability and can produce water to wells that tap them. The Lower Floridan aquifer includes all permeable strata that lie below the middle confining unit and above the base of the aquifer system. Beneath Hilton Head Island, South Carolina, the middle Floridan aquifer is now included as part of the Lower Floridan aquifer. The base of the Floridan aquifer system generally is located at the top of lower Eocene rocks in Georgia and the top of Paleocene rocks in South Carolina. The Upper and Lower Floridan aquifers are interconnected to varying degrees depending on the thickness and permeability of the middle confining unit that separates these aquifers. In most places, hydraulic head differences between the two aquifers range from a few inches to a few feet or more. Monitoring at several vertically clustered well-point sites where wells were set at different depths in the aquifer revealed variations in the degree of hydraulic separation with depth. In general, the head separation between the Upper and Lower Floridan aquifers increases with depth, which indicates that the deeper zones are more hydraulically separated than the shallower parts of the Lower Floridan aquifer.

Going Steady: Using multiple isotopes to test the steady-state assumption at the Susquehanna Shale Hills Critical Zone Observatory (Invited)

NASA Astrophysics Data System (ADS)

West, N.; Kirby, E.; Ma, L.; Bierman, P. R.

2013-12-01

Regolith-mantled hillslopes are ubiquitous features of most temperate landscapes, and their morphology reflects the climatically, biologically, and tectonically mediated interplay between regolith production and downslope transport. Despite intensive research, few studies have quantified both of these mass fluxes in the same field site. Here, we exploit two isotopic systems to quantify regolith production and transport within the Susquehanna Shale Hills Critical Zone Observatory (SSHO), in central Pennsylvania. We present an analysis of 131 meteoric 10Be measurements from regolith and bedrock to quantify rates of regolith transport, and compare these data with previously determined regolith production rates, measured using uranium-series isotopes. Regolith flux inferred from meteoric 10Be varies linearly with topographic gradient (determined from high-resolution LiDAR-based topography) along the upper portions of hillslopes in and adjacent to SSHO. However, regolith flux appears to depend on the product of gradient and regolith depth where regolith is thick, near the base of hillslopes. Meteoric 10Be inventories along 4 ridgetops within and adjacent to the SSHO indicate regolith residence times ranging from ~ 9 - 15 ky, similar to residence times inferred from U-series isotopes (6.7 × 3 ky - 15 × 8 ky). Similarly, the downslope flux of regolith (~ 500 - 1,000 m2/My) nearly balances production (850 × 22 m2/My - 960 × 530 m2/My). The combination of our results with U-series derived regolith production rates implies that regolith production and erosion rates along ridgecrests in the SSHO may be approaching steady state conditions over the Holocene.

76 FR 38975 - Safety Zone; Upper Mississippi River, Mile 856.0 to 855.0, Minneapolis, MN

Federal Register 2010, 2011, 2012, 2013, 2014

2011-07-05

... through July 24, 2011, World Sports and Marketing will sponsor the U.S. Wakeboard Nationals between Mile... INFORMATION CONTACT: If you have questions on this temporary rule, call or e-mail Chief Petty Officer Bryan Klostermeyer, Sector Upper Mississippi River Response Department at telephone (314) 269-2566, e-mail Bryan.K...

Physician decision-making in the management of work related upper extremity injuries.

PubMed

Szekeres, Mike; Macdermid, Joy C; Katchky, Adam; Grewal, Ruby

2018-05-22

Physicians working in a tertiary care injured worker clinic are faced with clinical decision-making that must balance the needs of patients and society in managing complex clinical problems that are complicated by the work-workplace context. The purpose of this study is to describe and characterize the decision-making process of upper extremity specialized surgeons when managing injured workers within a specialized worker's compensation clinic. Surgeons were interviewed in a semi-structured manner. Following each interview, the surgeon was also observed in a clinic visit during a new patient assessment, allowing observation of the interactional patterns between surgeon and patient, and comparison of the process described in the interview to what actually occurred during clinic visits. The primary central theme emerging from the surgeon interviews and the clinical observation was the focus on the importance of comprehensive assessment to make the first critical decision: an accurate diagnosis. Two subthemes were also found. The first of these involved the decision whether to proceed to management strategies or to continue with further investigation if the correct diagnosis is uncertain. Once the central theme of diagnosis was achieved, a second subtheme was highlighted; selecting appropriate management options, given the complexities of managing the injured worker, the workplace, and the compensation board. This study illustrates that upper extremity surgeons rely on their training and experience with upper extremity conditions to follow a sequential but iterative decision-making process to provide a more definitive diagnosis and treatment plan for workers with injuries that are often complex. The surgeons are challenged by the context which takes them out of their familiar zone of typical clinical practice to deal with the interactions between the injury, worker, work, workplace and insurer.

Multiple mantle upwellings through the transition zone beneath the Afar Depression?

NASA Astrophysics Data System (ADS)

Hammond, J. O.; Kendall, J. M.; Stuart, G. W.; Thompson, D. A.; Ebinger, C. J.; Keir, D.; Ayele, A.; Goitom, B.; Ogubazghi, G.

2012-12-01

Previous seismic studies using regional deployments of sensors in East-Africa show that low seismic velocities underlie Africa, but their resolution is limited to the top 200-300km of the Earth. Thus, the connection between the low velocities in the uppermost mantle and those imaged in global studies in the lower mantle is unclear. We have combined new data from Afar, Ethiopia with 7 other regional experiments and global network stations across Kenya, Ethiopia, Eritrea, Djibouti and Yemen, to produce high-resolution models of upper mantle P- and S-wave velocities to the base of the transition zone. Relative travel time tomographic inversions show that within the transition zone two focussed sharp-sided low velocity regions exist: one beneath the Western Ethiopian plateau outside the rift valley, and the other beneath the Afar depression. Estimates of transition zone thickness suggest that this is unlikely to be an artefact of mantle discontinuity topography as a transition zone of normal thickness underlies the majority of Afar and surrounding regions. However, a low velocity layer is evident directly above the 410 discontinuity, co-incident with some of the lowest seismic velocities suggesting that smearing of a strong low velocity layer of limited depth extent may contribute to the tomographic models in north-east Afar. The combination of seismic constraints suggests that small low temperature (<50K) upwellings may rise from a broader low velocity plume-like feature in the lower mantle. This interpretation is supported by numerical and analogue experiments that suggest the 660km phase change and viscosity jump may impede flow from the lower to upper mantle creating a thermal boundary layer at the base of the transition zone. This allows smaller, secondary upwellings to initiate and rise to the surface. These, combined with possible evidence of melt above the 410 discontinuity can explain the seismic velocity models. Our images of secondary upwellings suggest that there is no evidence for a plume in the classical sense (i.e. a narrow conduit). Instead, we propose that secondary upwellings rise from the base of the transition zone and connect with the northeast flowing African superswell in the upper mantle.

Structural control of the upper plate on the down-dip segmentation of subduction dynamics

NASA Astrophysics Data System (ADS)

Shi, Q.; Barbot, S.; Karato, S. I.; Shibazaki, B.; Matsuzawa, T.; Tapponnier, P.

2017-12-01

The geodetic and seismic discoveries of slow earthquakes in subduction zones have provided the observational evidence for the existence of the transition between megathrust earthquakes and the creeping behaviors. However, the mechanics behind slow earthquakes, and the period differential motion between the subducting slab and the overlying plate below the seismogenic zone, remain controversial. In Nankai subduction zone, the very-low-frequency earthquakes (VLFE), megathrust earthquakes, long-term slow earthquakes (duration of months or years) and the episodic tremor and slip zone (ETS) are located within the accretionary prism, the continental upper crust, the continental lower crust and the upmost mantle of the overriding plate, respectively. We use the rate-and-state friction law to simulate the periodic occurrence of VLFEs, megathrust earthquakes and the tremors in the ETS zone because of relatively high rock strength within these depth ranges. However, it is not feasible to use frictional instabilities to explain the long-term slow earthquakes in the lower crust where the ductile rock physics plays a significant role in the large-scale deformation. Here, our numerical simulations show that slow earthquakes at the depth of the lower crust may be the results of plastic instabilities in a finite volume of ductile material accompanying by the grain-size evolution. As the thickness of the fault zone increases with depth, deformation becomes distributed and the dynamic equilibrium of grain size, as a competition between thermally activated grain growth and damage-related grain size reduction, results in cycles of strain acceleration and strain deficit. In addition, we took into account the elevated pore pressure in the accretinary prism which is associated with small stress drop and low-frequency content of VLFEs and may contribute to the occurrence of tsunamigenic earthquakes. Hence, in our numerical simulations for the plate boundary system in Nankai, the down-sip segmentation of the subduction dynamic is attributed to the upper plate structure that vary with depth. The high pore pressure, grain-size evolution and alternation of the rock physics may explain the existence and the periodicity of different slow earthquakes from shallow to deep regions in the subduction zone.

Chemometric Study of Trace Elements in Hard Coals of the Upper Silesian Coal Basin, Poland

PubMed Central

Rompalski, Przemysław; Cybulski, Krzysztof; Chećko, Jarosław

2014-01-01

The objective of the study was the analysis of trace elements contents in coals of the Upper Silesian Coal Basin (USCB), which may pose a potential threat to the environment when emitted from coal processing systems. Productive carbon overburden in central and southern zones of the USCB is composed mostly of insulating tertiary formations of a thickness from a few m to 1,100 m, and is represented by Miocene and Pliocene formations. In the data study the geological conditions of the coal seams of particular zones of the USCB were taken into account and the hierarchical clustering analysis was applied, which enabled the exploration of the dissimilarities between coal samples of various zones of the USCB in terms of basic physical and chemical parameters and trace elements contents. Coals of the northern and eastern zones of the USCB are characterized by high average Hg and low average Ba, Cr, and Ni contents, whereas coals of southern and western zones are unique due to high average concentrations of Ba, Co, Cu, Ni, and V. Coals of the central part of the USCB are characterized by the highest average concentration of Mn and the lowest average concentrations of As, Cd, Pb, V, and Zn. PMID:24967424

Microtubule distribution in gravitropic protonemata of the moss Ceratodon

NASA Technical Reports Server (NTRS)

Schwuchow, J.; Sack, F. D.; Hartmann, E.

1990-01-01

Tip cells of dark-grown protonemata of the moss Ceratodon purpureus are negatively gravitropic (grow upward). They possess a unique longitudinal zonation: (1) a tip group of amylochloroplasts in the apical dome, (2) a plastid-free zone, (3) a zone of significant plastid sedimentation, and (4) a zone of mostly non-sedimenting plastids. Immunofluorescence of vertical cells showed microtubules distributed throughout the cytoplasm in a mostly axial orientation extending through all zones. Optical sectioning revealed a close spatial association between microtubules and plastids. A majority (two thirds) of protonemata gravistimulated for > 20 min had a higher density of microtubules near the lower flank compared to the upper flank in the plastid-free zone. This apparent enrichment of microtubules occurred just proximal to sedimented plastids and near the part of the tip that presumably elongates more to produce curvature. Fewer than 5% of gravistimulated protonemata had an enrichment in microtubules near the upper flank, whereas 14% of vertical protonemata were enriched near one of the side walls. Oryzalin and amiprophos-methyl (APM) disrupted microtubules, gravitropism, and normal tip growth and zonation, but did not prevent plastid sedimentation. We hypothesize that a microtubule redistribution plays a role in gravitropism in this protonema. This appears to be the first report of an effect of gravity on microtubule distribution in plants.

Slab temperature controls on the Tonga double seismic zone and slab mantle dehydration

PubMed Central

Wei, S. Shawn; Wiens, Douglas A.; van Keken, Peter E.; Cai, Chen

2017-01-01

Double seismic zones are two-layered distributions of intermediate-depth earthquakes that provide insight into the thermomechanical state of subducting slabs. We present new precise hypocenters of intermediate-depth earthquakes in the Tonga subduction zone obtained using data from local island–based, ocean-bottom, and global seismographs. The results show a downdip compressional upper plane and a downdip tensional lower plane with a separation of about 30 km. The double seismic zone in Tonga extends to a depth of about 300 km, deeper than in any other subduction system. This is due to the lower slab temperatures resulting from faster subduction, as indicated by a global trend toward deeper double seismic zones in colder slabs. In addition, a line of high seismicity in the upper plane is observed at a depth of 160 to 280 km, which shallows southward as the convergence rate decreases. Thermal modeling shows that the earthquakes in this “seismic belt” occur at various pressures but at a nearly constant temperature, highlighting the important role of temperature in triggering intermediate-depth earthquakes. This seismic belt may correspond to regions where the subducting mantle first reaches a temperature of ~500°C, implying that metamorphic dehydration of mantle minerals in the slab provides water to enhance faulting. PMID:28097220

The Dual Role of Vegetation as a Constraint on Mass and Energy Flux into the Critical Zone and as an Emergent Property of Geophysical Critical Zone Structure

NASA Astrophysics Data System (ADS)

Brooks, P. D.; Swetnam, T. L.; Barnard, H. R.; Singha, K.; Harpold, A.; Litvak, M. E.

2017-12-01

Spatial patterns in vegetation long have been used to scale both landsurface-atmosphere exchanges of water and carbon as well as to infer subsurface structure. These pursuits typical proceed in isolation and rarely do inferences gained from one community propagate to related efforts in another. Perhaps more importantly, vegetation often is treated as an emergent property of landscape-climate interactions rather than an active modifier of both critical zone structure and energy fluxes. We posit that vegetation structure and activity are under utilized as a tool towards understanding landscape evolution and present examples that begin to disentangle the role of vegetation as both an emergent property and an active control on critical zone structure and function. As climate change, population growth, and land use changes threaten water resources worldwide, the need for the new insights vegetation can provide becomes not just a basic science priority, but a pressing applied science question with clear societal importance. This presentation will provide an overview of recent efforts to address the dual role of vegetation in both modifying and reflecting critical zone structure in the western North American forests. For example, interactions between topography and stand scale vegetation structure influence both solar radiation and turbulence altering landscape scale partitioning of evaporation vs transpiration with major impacts of surface water supply. Similarly, interactions between topographic shading, lateral redistribution of plant available water, and subsurface storage create a mosaic of drought resistance and resilience across complex terrain. These complex interactions between geophysical and vegetation components of critical zone structure result in predictable patterns in catchment scale hydrologic partitioning within individual watersheds while simultaneously suggesting testable hypotheses for why catchments under similar climate regimes respond so differently to drought stress.

Sedimentation across the central California oxygen minimum zone: an alternative coastal upwelling sequence.

USGS Publications Warehouse

Vercoutere, T.L.; Mullins, H.T.; McDougall, K.; Thompson, J.B.

1987-01-01

Distribution, abundance, and diversity of terrigenous, authigenous, and biogenous material provide evidence of the effect of bottom currents and oxygen minimum zone (OMZ) on continental slope sedimentation offshore central California. Three major OMZ facies are identified, along the upper and lower edges of OMZ and one at its core.-from Authors

[Effect of GABA, sodium glutamate and glycine on evoked potentials in the dental zones of the cerebral cortex].

PubMed

Degtiarev, V P

1979-01-01

Intraventricular administration of gamma-aminobutyric acid (GABA) and glycine decreased, whereas sodium glutamate increased the amplitude of primary responses of dental zones of the somatosensory cortex, which arose during electric stimulation of the pulp of the rabbit upper incisors. No changes in the latent periods were recorded.

Implant therapy in the esthetic zone: smile line assessment.

PubMed

Kourkouta, Stella

2011-04-01

Assessment of the smile or lip line is imperative when implant therapy is carried out in the esthetic zone. The smile is generally defined as high, average, or low. Females are reported to have higher lip lines than males, which means that they are at greater risk when placing and restoring implants in the esthetic zone. Maximum upper lip elevation, usually observed during a strained posed smile, should be assessed. This paper discusses some clinical observations and concepts in relation to smile line assessment for implant therapy in the esthetic zone. (Int J Periodontics Restorative Dent 2011;31:195-201.).

Geologic Map of the Kings Mountain and Grover Quadrangles, Cleveland and Gaston Counties, North Carolina, and Cherokee and York Counties, South Carolina

USGS Publications Warehouse

Horton, J. Wright

2008-01-01

This geologic map of the Kings Mountain and Grover 7.5-min quadrangles, N.C.-S.C., straddles a regional geological boundary between the Inner Piedmont and Carolina terranes. The Kings Mountain sequence (informal name) on the western flank of the Carolina terrane in this area includes the Neoproterozoic Battleground and Blacksburg Formations. The Battleground Formation has a lower part consisting of metavolcanic rocks and interlayered schist and an upper part consisting of quartz-sericite phyllite and schist interlayered with quartz-pebble metaconglomerate, aluminous quartzite, micaceous quartzite, manganiferous rock, and metavolcanic rocks. The Blacks-burg Formation consists of phyllitic metasiltstone interlayered with thinner units of marble, laminated micaceous quartzite, hornblende gneiss, and amphibolite. Layered metamorphic rocks of the Inner Piedmont terrane include muscovite-biotite gneiss, muscovite schist, and amphibolite. The Kings Mountain sequence has been intruded by metatonalite and metatrondhjemite (Neoproterozoic), metagabbro and metadiorite (Paleozoic?), and the High Shoals Granite (Pennsylvanian). Layered metamorphic rocks of the Inner Piedmont in this area have been intruded by the Toluca Granite (Ordovician?), the Cherryville Granite and associated pegmatite (Mississippian), and spodumene pegmatite (Mississippian). Diabase dikes (early Jurassic) are locally present throughout the area. Ductile fault zones of regional scale include the Kings Mountain and Kings Creek shear zones. In this area, the Kings Mountain shear zone forms the boundary between the Inner Piedmont and Carolina terranes, and the Kings Creek shear zone separates the Battleground Formation from the Blacksburg Formation. Structural styles change across the Kings Mountain shear zone from steeply dipping layers, foliations, and folds on the southeast to gently and moderately dipping layers, foliations, and recumbent folds on the northwest. Mineral assemblages in the Kings Mountain sequence show a westward decrease from upper amphibolite facies (sillimanite zone) near the High Shoals Granite in the eastern side of the map area to upper greenschist (epidote-amphibolite) facies in the south-central part of the area near the Kings Mountain shear zone. Amphibolite-facies mineral assemblages in the Inner Piedmont terrane increase in grade from the kyanite zone near the Kings Mountain shear zone to the sillimanite zone in the northwestern part of the map area. Surficial deposits include alluvium in the stream valleys and colluvium along ridges and steep slopes. These quadrangles are unusual in the richness and variety of the mineral deposits that they contain, which include spodumene (lithium), cassiterite (tin), mica, feldspar, silica, clay, marble, kyanite and sillimanite, barite, manganese, sand and gravel, gold, pyrite, and iron.

Photosynthetic characteristics and mycosporine-like amino acids under UV radiation: a competitive advantage of Mastocarpus stellatus over Chondrus crispus at the Helgoland shoreline?

NASA Astrophysics Data System (ADS)

Bischof, K.; Kräbs, G.; Hanelt, D.; Wiencke, C.

2000-05-01

Chondrus crispus and Mastocarpus stellatus both inhabit the intertidal and upper sublittoral zone of Helgoland, but with C. crispus generally taking a lower position. Measurements of chlorophyll fluorescence, activity of ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO), and content and composition of UV absorbing mycosporine-like amino acids (MAAs) were conducted in the laboratory, to test whether susceptibility to UV radiation may play a role in the vertical distribution of these two species. Effective and maximal quantum yield of photochemistry as well as maximal electron transport rate (ETRmax) in C. crispus were more strongly affected by UV-B radiation than in M. stellatus. In both species, no negative effects of the respective radiation conditions were found on total activity of RubisCO. Total MAA content in M. stellatus was up to 6-fold higher than in C. crispus and the composition of MAAs in the two species was different. The results indicate that, among others, UV-B sensitivity may be a factor restricting C. crispus to the lower intertidal and upper sublittoral zone, whereas M. stellatus is better adapted to UV radiation and is therefore more competitive in the upper intertidal zone.

Quality of economically extractable coal beds in the Gillette coal field as compared with other Tertiary coal beds in the Powder River basin, Wyoming and Montana

USGS Publications Warehouse

Ellis, Margaret S.

2002-01-01

The Powder River Basin, and specifically the Gillette coal field, contains large quantities of economically extractable coal resources. These coal resources have low total sulfur content and ash yield, and most of the resources are subbituminous in rank. A recent U.S Geological Survey study of economically extractable coal in the Gillette coal field focused on five coal beds, the Wyodak rider, Upper Wyodak, Canyon, Lower Wyodak-Werner, and Gates/Kennedy. This report compares the coal quality of these economically extractable coal beds to coal in the Wyodak-Anderson coal zone in the Powder River Basin and in the Gillette coal field (Flores and others, 1999) and other produced coal in the Gillette coal field (Glass, 2000). The Upper Wyodak, Canyon, and Lower Wyodak/Werner beds are within the Wyodak-Anderson coal zone. Compared with all coal in the Wyodak-Anderson coal zone, both throughout the Powder River Basin and just within the Gillette coal field; the thick, persistent Upper Wyodak coal bed in the Gillette coal field has higher mean gross calorific value (8,569 Btu/lb), lower mean ash yield (5.8 percent), and lower mean total sulfur content (0.46 percent).

Teleseismic P and S wave attenuation constraints on temperature and melt of the upper mantle in the Alaska Subduction Zone.

NASA Astrophysics Data System (ADS)

Soto Castaneda, R. A.; Abers, G. A.; Eilon, Z.; Christensen, D. H.

2017-12-01

Recent broadband deployments in Alaska provide an excellent opportunity to advance our understanding of the Alaska-Aleutians subduction system, with implications for subduction processes worldwide. Seismic attenuation, measured from teleseismic body waves, provides a strong constraint on thermal structure as well as an indirect indication of ground shaking expected from large intermediate-depth earthquakes. We measure P and S wave attenuation from pairwise amplitude and phase spectral ratios for teleseisms recorded at 204 Transportable Array, Alaska Regional, and Alaska Volcano Observatory, SALMON (Southern Alaska Lithosphere & Mantle Observation Network) and WVLF (Wrangell Volcanics & subducting Lithosphere Fate) stations in central Alaska. The spectral ratios are inverted in a least squares sense for differential t* (path-averaged attenuation operator) and travel time anomalies at every station. Our preliminary results indicate a zone of low attenuation across the forearc and strong attenuation beneath arc and backarc in the Cook Inlet-Kenai region where the Aleutian-Yakutat slab subducts, similar to other subduction zones. This attenuation differential is observed in both the volcanic Cook Inlet segment and amagmatic Denali segments of the Aleutian subduction zone. By comparison, preliminary results for the Wrangell-St. Elias region past the eastern edge of the Aleutian slab show strong attenuation beneath the Wrangell Volcanic Field, as well as much further south than in the Cook Inlet-Kenai region. This pattern of attenuation seems to indicate a short slab fragment in the east of the subduction zone, though the picture is complex. Results also suggest the slab may focus or transmit energy with minimal attenuation, adding to the complexity. To image the critical transition between the Alaska-Aleutian slab and the region to its east, we plan to incorporate new broadband data from the WVLF array, an ongoing deployment of 37 PASSCAL instruments installed in 2016. These stations have 10-20 km spacing, spanning the edge of the subducting slab, and so will provide a zone of increased resolution in the region where slab behavior is poorly understood. We will discuss these data in the context of enigmatic Wrangell volcanism and its relationship to the eastern end of the Alaska-Aleutian Wadati-Benioff zone.

Element mobility studies of two drill-cores from the Götemar Granite (Kråkemåla test site), southeast Sweden

USGS Publications Warehouse

Smellie, John A.T.; Stuckless, John S.

1985-01-01

The pervasive alteration and the more recent mobilisation of U are evident to a depth of at least 600 m. The effects are most prevalent along major fracture zones and within the upper 250–300 m of one drill-hole where a high frequency of crush zones has been noted. Higher Fe oxidation ratios, higher Rb contents, lower U contents and correspondingly higher Th/U ratios, all characterise this zone.

Environmental Assessment: For Joint Biological Point Detection System (JBPDS) at Multiple Test Ranges, Eglin Air Force Base, Florida

DTIC Science & Technology

2003-06-01

bed. This clay layer restricts the downward migration of pollutants and restricts saline water from Choctawhatchee Bay and the Gulf of Mexico from...Because it is saline , the Lower Limestone unit is not used as a water source (U.S. Air Force, 1995). Groundwater storage and movement in the Upper... purslane , among others. Inland from the produne zone is the “scrub” zone. Vegetation found in this zone is usually stunted and wind/salt sprayed

Pore pressure development beneath the décollement at the Nankai subduction zone: Implications for plate boundary fault strength and sediment dewatering

NASA Astrophysics Data System (ADS)

Skarbek, Robert M.; Saffer, Demian M.

2009-07-01

Despite its importance for plate boundary fault processes, quantitative constraints on pore pressure are rare, especially within fault zones. Here, we combine laboratory permeability measurements from core samples with a model of loading and pore pressure diffusion to investigate pore fluid pressure evolution within underthrust sediment at the Nankai subduction zone. Independent estimates of pore pressure to ˜20 km from the trench, combined with permeability measurements conducted over a wide range of effective stresses and porosities, allow us to reliably simulate pore pressure development to greater depths than in previous studies and to directly quantify pore pressure within the plate boundary fault zone itself, which acts as the upper boundary of the underthrusting section. Our results suggest that the time-averaged excess pore pressure (P*) along the décollement ranges from 1.7-2.1 MPa at the trench to 30.2-35.9 MPa by 40 km landward, corresponding to pore pressure ratios of λb = 0.68-0.77. For friction coefficients of 0.30-0.40, the resulting shear strength along the décollement remains <12 MPa over this region. When noncohesive critical taper theory is applied using these values, the required pore pressure ratios within the wedge are near hydrostatic (λw = 0.41-0.59), implying either that pore pressure throughout the wedge is low or that the fault slips only during transient pulses of elevated pore pressure. In addition, simulated downward migration of minima in effective stress during drainage provides a quantitative explanation for down stepping of the décollement that is consistent with observations at Nankai.

Three-dimensional modeling of pull-apart basins: implications for the tectonics of the Dead Sea Basin

USGS Publications Warehouse

Katzman, Rafael; ten Brink, Uri S.; Lin, Jian

1995-01-01

We model the three-dimensional (3-D) crustal deformation in a deep pull-apart basin as a result of relative plate motion along a transform system and compare the results to the tectonics of the Dead Sea Basin. The brittle upper crust is modeled by a boundary element technique as an elastic block, broken by two en echelon semi-infinite vertical faults. The deformation is caused by a horizontal displacement that is imposed everywhere at the bottom of the block except in a stress-free “shear zone” in the vicinity of the fault zone. The bottom displacement represents the regional relative plate motion. Results show that the basin deformation depends critically on the width of the shear zone and on the amount of overlap between basin-bounding faults. As the width of the shear zone increases, the depth of the basin decreases, the rotation around a vertical axis near the fault tips decreases, and the basin shape (the distribution of subsidence normalized by the maximum subsidence) becomes broader. In contrast, two-dimensional plane stress modeling predicts a basin shape that is independent of the width of the shear zone. Our models also predict full-graben profiles within the overlapped region between bounding faults and half-graben shapes elsewhere. Increasing overlap also decreases uplift near the fault tips and rotation of blocks within the basin. We suggest that the observed structure of the Dead Sea Basin can be described by a 3-D model having a large overlap (more than 30 km) that probably increased as the basin evolved as a result of a stable shear motion that was distributed laterally over 20 to 40 km.

Seam-weld quality of modern ERW/HFI line pipe

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

Groeneveld, T.P.; Barnes, C.R.

1991-09-01

This study was undertaken to determine whether the seam-weld quality of modern ERW (electric resistance-welded)/HFI (high-frequency induction) welded pipe has been improved and justifies more widespread use of this type of pipe in critical applications. Wider use of ERW/HFI line pipe in gas-transmission lines would be expected to reduce construction costs. Five recently produced, heavy wall pipes fabricated using high-frequency electric-resistance welding (ERW) processes to make the seam weld and one pipe fabricated using the high-frequency induction (HFI) welding process to make the seam weld were studied. Four of the pipes were Grade X-60, one was Grade X-65, and onemore » was Grade X-70. All of the pipes were produced from microalloyed, controlled-rolled steels, and the weld zones were post-weld normalized. Ultrasonic inspection of the seam welds in the six pipe sections evaluated revealed no indications of defects. The tensile properties of all of the weld zones exceeded the minimum specified yield strengths for the respective grades of pipe and all of the pipes exhibited ductile failures either in the weld zone or in the base metal. Five of the six pipes exhibited ductile failures either in the weld zone or in the base metal. Five of the six pipes exhibited relatively low 85% shear area transition temperatures and relatively high upper-shelf energy absorptions as determined with Charpy V-notch specimens. In addition, for two of the three joints of pipe for which the properties were determined at both ends of the pipe, the tensile and impact properties showed little variation from end-to-end. However, for the other joint of pipe, the impact properties varied substantially from one end to the other.« less

Simulation of saltwater movement in the Floridan aquifer system, Hilton Head Island, South Carolina

USGS Publications Warehouse

Bush, Peter W.

1988-01-01

Freshwater to supply Hilton Head Island, S.C., is obtained from the upper permeable zone of the Upper Floridan aquifer. Long-term pumping at Savannah, Ga., and the steadily increasing pumping on Hilton Head Island, have lowered Upper Floridan heads near the center of the island from about 10 feet above sea level to about 6 to 7 feet below sea level. The seaward hydraulic gradient that existed before pumping began has been reversed, thus increasing the potential for saltwater intrusion. Simulations of predevelopment, recent, and future ground-water flow in the Floridan aquifer system beneath the north end of Hilton Head Island and Port Royal Sound are presented. A finite-element model for fluid-density-dependent ground-water flow and solute transport was used in cross section. The general configuration of the simulated predevelopment flowfield is typical of a coastal aquifer having a seaward gradient in the freshwater. The freshwater flows toward Port Royal Sound over an intruding wedge of saltwater. The simulated flowfield at the end of 1983 shows that ground water in the Floridan aquifer system beneath most of Hilton Head Island has reversed its predevelopment direction and is moving toward Savannah. The distribution of chloride concentrations, based on simulation at the end of 1983, is about the same as the predevelopment distribution of chloride concentrations obtained from simulation. Results of two 50-year simulations from 1983 to 2034 suggest that there will be no significant threat of saltwater intrusion into the upper permeable zone of the Upper Floridan aquifer if heads on Hilton Head Island remain at current levels for the next 45 to 50 years. However, if head decline continues at the historical rate, any flow that presently occurs from the north end of the island toward Port Royal Sound will cease, allowing lateral intrusion of saltwater to proceed. Even under these conditions, chloride concentrations in the upper permeable zone of the Upper Floridan aquifer beneath Hilton Head Island should remain below 250 milligrams per liter for the next 45 to 50 years. Aquifer properties and selected boundary conditions were tested with several 1,000-year simulations which show that lateral permeability, transverse dispersivity, and landward boundary flow have the most influence on saltwater movement in the Upper Floridan aquifer.

Seismic Velocity Gradients Across the Transition Zone

NASA Astrophysics Data System (ADS)

Escalante, C.; Cammarano, F.; de Koker, N.; Piazzoni, A.; Wang, Y.; Marone, F.; Dalton, C.; Romanowicz, B.

2006-12-01

One-D elastic velocity models derived from mineral physics do a notoriously poor job at predicting the velocity gradients in the upper mantle transition zone, as well as some other features of models derived from seismological data. During the 2006 CIDER summer program, we computed Vs and Vp velocity profiles in the upper mantle based on three different mineral physics approaches: two approaches based on the minimization of Gibbs Free Energy (Stixrude and Lithgow-Bertelloni, 2005; Piazzoni et al., 2006) and one obtained by using experimentally determined phase diagrams (Weidner and Wang, 1998). The profiles were compared by assuming a vertical temperature profile and two end-member compositional models, the pyrolite model of Ringwood (1979) and the piclogite model of Anderson and Bass (1984). The predicted seismic profiles, which are significantly different from each other, primarily due to different choices of properties of single minerals and their extrapolation with temperature, are tested against a global dataset of P and S travel times and spheroidal and toroidal normal mode eigenfrequencies. All the models derived using a potential temperature of 1600K predict seismic velocities that are too slow in the upper mantle, suggesting the need to use a colder geotherm. The velocity gradient in the transition zone is somewhat better for piclogite than for pyrolite, possibly indicating the need to increase Ca content. The presence of stagnant slabs in the transition zone is a possible explanation for the need for 1) colder temperature and 2) increased Ca content. Future improvements in seismic profiles obtained from mineral physics will arise from better knowledge of elastic properties of upper mantle constituents and aggregates at high temperature and pressure, a better understanding of differences between thermodynamic models, and possibly the effect of water through and on Q. High resolution seismic constraints on velocity jumps at 400 and 660 km also need to be included. earth.org/2006/workshop.html

Upper Neoproterozoic-Lower Cambrian sedimentary successions in the Central Iberian Zone (Spain): sequence stratigraphy, petrology and chemostratigraphy. Implications for other European zones

NASA Astrophysics Data System (ADS)

Valladares, M. I.; Barba, P.; Ugidos, J. M.; Colmenero, J. R.; Armenteros, I.

The Upper Neoproterozoic-Lower Cambrian sedimentary succession in the central areas of the Central Iberian Zone has been subdivided into 12 mostly siliciclastic lithostratigraphic units, ranging in thickness between 1800 and 3900m. The lithology and facies of each unit are described and the facies associations are interpreted. The facies resulted mainly from turbidity currents and debris flows and, to a lesser extent, from submarine slides and traction flows. The facies associations suggest that sedimentation took place in slope and base-of-slope environments. Two depositional sequences are recognized, separated by a type-1 unconformity. The lower sequence is of Late Neoproterozoic age (units I-IV) and exhibits lowstand, transgressive, and highstand systems tracts. Most of the upper sequence is probably of Early Cambrian age (units V-XII). It begins at the base of unit V and possibly ends with the Tamames Limestone Formation. The upper sequence records a lowstand systems tract and minor-order sea-level oscillations. In the Cambrian units there are higher amounts of feldspar and smaller quantities of intrabasinal clasts than in the Neoproterozoic units. The modal data plot close to the Q-L and Qm-Lt sides of Q-F-L and Qm-F-Lt triangular diagrams, suggesting a provenance from a recycled orogen evolving into a provenance from a craton interior towards the top of the succession. The chemical results, based mainly on Al2O3, TiO2, Zr, and Nb abundances in shales from all the units, strongly suggest a gradual compositional change within this sedimentary succession. Together with the petrological data, the chemical results do not reveal any obvious coeval volcanic contribution to the sediments. On the basis of the chemical data, a comparison is made with other European zones containing detrital sediments composed of reworked crustal components.

Geometry and segmentation of the North Anatolian Fault beneath the Marmara Sea, Turkey, deduced from long-term ocean bottom seismographic observations

NASA Astrophysics Data System (ADS)

Yamamoto, Yojiro; Takahashi, Narumi; Pinar, Ali; Kalafat, Dogan; Citak, Seckin; Comoglu, Mustafa; Polat, Remzi; Kaneda, Yoshiyuki

2017-04-01

Both the geometry and the depth of the seismogenic zone of the North Anatolian Fault under the Marmara Sea (the Main Marmara Fault; MMF) are poorly understood, in part because of the fault's undersea location. We have started a series of long-term ocean bottom seismographs (OBSs) observation since 2014, as a part of the SATREPS collaborative project between Japan and Turkey namely "Earthquake and Tsunami Disaster Mitigation in the Marmara Region and Disaster Education in Turkey". We recorded 10 months of microseismic data with a dense array of OBSs from Sep. 2014 to Jul. 2015 and then applied double-difference relocation and 3-D tomographic modeling to obtain precise hypocenters on the MMF beneath the central and western Marmara Sea. The hypocenters show distinct lateral changes along the MMF: (1) Both the upper and lower crust beneath the Western High are seismically active and the maximum focal depth reaches 26 km, (2) seismic events are confined to the upper crust beneath the region extending from the eastern part of the Central Basin to the Kumburgaz Basin, and (3) the magnitude and direction of dip of the main fault changes under the Central Basin, where there is also an abrupt change in the depth of the lower limit of the seismogenic zone. We attribute this change to a segment boundary of the MMF. Our data show that the upper limit of the seismogenic zone corresponds to sedimentary basement. We also identified several inactive seismicity regions within the upper crust along the MMF; their spatial extent beneath the Kumburgaz Basin is greater than beneath the Western High. From the comparison with seafloor extensometer data, we consider that these inactive seismicity regions might indicate zones of strong coupling that are accumulating stress for release during future large earthquakes. In this presentation, we will also show the preliminary result of our second phase observation from Jul. 2015 to Jun. 2016.

Formulating a coastal zone health metric for landuse impact management in urban coastal zones.

PubMed

Anilkumar, P P; Varghese, Koshy; Ganesh, L S

2010-11-01

The need for ICZM arises often due to inadequate or inappropriate landuse planning practices and policies, especially in urban coastal zones which are more complex due to the larger number of components, their critical dimensions, attributes and interactions. A survey of literature shows that there is no holistic metric for assessing the impacts of landuse planning on the health of a coastal zone. Thus there is a need to define such a metric. The proposed metric, CHI (Coastal zone Health Indicator), developed on the basis of coastal system sustainability, attempts to gauge the health status of any coastal zone. It is formulated and modeled through an expert survey and pertains to the characteristic components of coastal zones, their critical dimensions, and relevant attributes. The proposed metric is applied to two urban coastal zones and validated. It can be used for more coast friendly and sustainable landuse planning/masterplan preparation and thereby for the better management of landuse impacts on coastal zones. Copyright 2010 Elsevier Ltd. All rights reserved.

AmeriFlux US-CZ2 Sierra Critical Zone, Sierra Transect, Ponderosa Pine Forest, Soaproot Saddle

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

Goulden, Michael

This is the AmeriFlux version of the carbon flux data for the site US-CZ2 Sierra Critical Zone, Sierra Transect, Ponderosa Pine Forest, Soaproot Saddle. Site Description - Half hourly data are available at https://www.ess.uci.edu/~california/. This site is one of four Southern Sierra Critical Zone Observatory flux towers operated along an elevation gradient (sites are USCZ1, USCZ2, USCZ3 and USCZ4). This site is an oak/pine forest, with occasional thinning and wildfire, a prescribed understory burn ~2012, and severe drought and ~80% canopy mortality in 2011-15

AmeriFlux US-CZ3 Sierra Critical Zone, Sierra Transect, Sierran Mixed Conifer, P301

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

Goulden, Michael

This is the AmeriFlux version of the carbon flux data for the site US-CZ3 Sierra Critical Zone, Sierra Transect, Sierran Mixed Conifer, P301. Site Description - Half hourly data are available at https://www.ess.uci.edu/~california/. This site is one of four Southern Sierra Critical Zone Observatory flux towers operated along an elevation gradient (sites are USCZ1, USCZ2, USCZ3 and USCZ4). This site is a pine/fir forest; it historically experienced logging and wildfire, was thinned in ~2012, and experienced severe drought and ~20% canopy mortality in 2011-15.

Environmental drivers of soil microbial community structure and function at the Avon River Critical Zone Observatory.

PubMed

Gleeson, Deirdre; Mathes, Falko; Farrell, Mark; Leopold, Matthias

2016-11-15

The Critical Zone is defined as the thin, permeable layer from the tops of the trees to the bottom of the bedrock that sustains terrestrial life on Earth. The geometry and shape of the various weathering zones are known as the critical zone architecture. At the centre of the Critical Zone are soils and the microorganisms that inhabit them. In Western Australia, the million-year-old stable weathering history and more recent lateral erosion during the past hundreds of thousands of years have created a geomorphic setting where deep weathering zones are now exposed on the surface along the flanks of many lateritic hills. These old weathering zones provide diverse physical and chemical properties that influence near surface pedologic conditions and thus likely shape current surface microbiology. Here, we present data derived from a small lateritic hill on the UWA Farm Ridgefield. Spatial soil sampling revealed the contrasting distribution patterns of simple soil parameters such as pH (CaCl2) and electric conductivity. These are clearly linked with underlying changes of the critical zone architecture and show a strong contrast with low values of pH3.3 at the top of the hill to pH5.3 at the bottom. These parameters were identified as major drivers of microbial spatial variability in terms of bacterial and archaeal community composition but not abundance. In addition, we used sensitive (14)C labelling to assess turnover of three model organic nitrogen compounds - an important biogeochemical functional trait relating to nutrient availability. Though generally rapid and in the order of rates reported elsewhere (t½<5h), some points in the sampling area showed greatly reduced turnover rates (t½>10h). In conclusion, we have shown that the weathering and erosion history of ancient Western Australia affects the surface pedology and has consequences for microbial community structure and function. Copyright © 2016 Elsevier B.V. All rights reserved.

Development of a Unified Hydrostratigraphic Framework for the Floridan Aquifer System in Central and Southern Florida

NASA Astrophysics Data System (ADS)

Reese, R. S.

2008-05-01

The mostly carbonate Floridan aquifer system (FAS) of central and southern Florida is a widely used resource with a complex hydrostratigraphic framework that is managed primarily in a subregional context according to water management jurisdictional boundaries. As use of the FAS increases, a consistent regional hydrostratigraphic framework is needed for effective management across these boundaries. Stratigraphic marker horizons within and near the top of FAS were delineated and mapped to develop a preliminary, correlative stratigraphic framework. This framework was used to identify and determine aquifers, subaquifers, and confining units and map their spatial distribution. These horizons are based on lithologic changes and geophysical log signatures identified in previous studies, and they were extended throughout the study area primarily by correlation of natural gamma-ray logs. The FAS consists of the Upper Floridan aquifer, middle confining unit, and Lower Floridan aquifer. A regional, productive zone is delineated and informally referred to as the Avon Park permeable zone. This zone is present over most of the study area and is characterized by thick units of dolostone with interbedded limestone and high fracture permeability. The zone has been identified in different regions in previous studies, either as the upper part of the Lower Floridan aquifer or as the lower part of the Upper Floridan aquifer. In this study it is generally considered to be within the middle confining unit. Transmissivity of the Avon Park permeable zone, a major source of water supply, generally ranges from less than 1x104 up to 1.6x106 ft2/day, and is greatest in central Florida where dolomite is developed as a major component of the zone. A large area of low transmissivity (less than 105 ft2/day) in southern Florida coincides with an area where limestone is the predominant lithology within the zone. Major uses of the FAS now include withdrawal for public and agricultural supply, including treatment with reverse osmosis, aquifer storage and recovery, and disposal of treated wastewater. Water-level and water-quality conflicts could arise between these competing uses, and delineating the extent and hydraulic connectivity of the Avon Park permeable zone within the FAS may help managers and others predict and minimize such conflicts.

The permeability of fault zones in the upper continental crust: statistical analysis from 460 datasets, updated depth-trends, and permeability contrasts between fault damage zones and protoliths.

NASA Astrophysics Data System (ADS)

Scibek, J.; Gleeson, T. P.; Ingebritsen, S.; McKenzie, J. M.

2017-12-01

Fault zones are an important part of the hydraulic structure of the Earth's crust and influence a wide range of Earth processes and a large amount of test data has been collected over the years. We conducted a meta-analysis of global of fault zone permeabilities in the upper brittle continental crust, using about 10,000 published research items from a variety of geoscience and engineering disciplines. Using 460 datasets at 340 localities, the in-situ bulk permeabilities (>10's meters scale, including macro-fractures) and matrix permeabilities (drilled core samples or outcrop spot tests) are separated, analyzed, and compared. The values have log-normal distributions and we analyze the log-permeability values. In the fault damage zones of plutonic and metamorphic rocks the mean bulk permeability was 1x10-14m2, compared to matrix mean of 1x10-16m2. In sedimentary siliciclastic rocks the mean value was the same for bulk and matrix permeability (4x10-14m2). More useful insights were determined from the regression analysis of paired permeability data at all sites (fault damage zone vs. protolith). Much of the variation in fault permeability is explained by the permeability of protolith: in relatively weak volcaniclastic and clay-rich rocks up to 70 to 88% of the variation is explained, and only 20-30% in plutonic and metamorphic rocks. We propose a revision at shallow depths for previously published upper-bound curves for the "fault-damaged crust " and the geothermal-metamorphic rock assemblage outside of major fault zones. Although the bounding curves describe the "fault-damaged crust" permeability parameter space adequately, the only statistically significant permeability-depth trend is for plutonic and metamorphic rocks (50% of variation explained). We find a depth-dependent systematic variation of the permeability ratio (fault damage zone / protolith) from the in-situ bulk permeability global data. A moving average of the log-permeability ratio value is 2 to 2.5 (global mean is 2.2). Although the data is unevenly distributed with depth, the present evidence is that the permeability ratio is at a maximum at depths 1 to 2 kilometers, decreases with depth below 2km, and is also lower near the ground surface.

Upper critical fields and two-band superconductivity in Sr 1-xEu x(Fe 0.89Co 0.11)₂As₂ (x=0.20 and 0.46)

DOE PAGES

Hu, Rongwei; Mun, Eun Deok; Altarawneh, M. M.; ...

2012-02-13

The upper critical fields H c2(T) of single crystals of Sr 1-xEu x(Fe₀.₈₉Co₀.₁₁)₂As₂ (x=0.20 and 0.46) were determined by radio-frequency penetration depth measurements in pulsed magnetic fields. H c2(T) approaches the Pauli limiting field but shows an upward curvature with an enhancement from the orbital limited field, as inferred from the Werthamer-Helfand-Hohenberg theory. We discuss the temperature dependence of the upper critical fields and the decreasing anisotropy using a two-band BCS model.

Regional Vp, Vs, Vp/Vs, and Poisson's ratios across earthquake source zones from Memphis, Tennessee, to St. Louis, Missouri

USGS Publications Warehouse

Catchings, R.D.

1999-01-01

Models of P- and S-wave velocity, Vp/Vs ratios, Poisson's ratios, and density for the crust and upper mantle are presented along a 400-km-long profile trending from Memphis, Tennessee, to St. Louis, Missouri. The profile crosses the New Madrid seismic zone and reveals distinct regional variations in the crustal velocity structure north and south of the latitude of New Madrid. In the south near Memphis, the upper few kilometers of the crust are dominated by upper crustal sedimentary basins or graben with P-wave velocities less than 5 km/sec and S-wave velocities of about 2 km/sec. P-wave velocities of the upper and middle crust range from 6.0 to 6.5 km/sec at depths above 25 km, and corresponding S-wave velocities range from 3.5 to 3.7 km/sec. The lower crust consists of a high-velocity layer (Vp = 7.4 km/sec; Vs ~4.2 km/sec) that is up to 20-km thick at the latitude of New Madrid but thins to about 15 km near Memphis. To the north, beneath the western-most Illinois basin, low-velocity (Vp < 5 km/sec; Vs < 2.3 km/sec) sedimentary basins are less than 1-km deep. The average velocities (Vp = 6.0 km/sec; Vs = 3.5 km/sec) of the underlying, near-surface rocks argue against large thickness of unconsolidated noncarbonate sediments within 50 km of the western edge of the Illinois basin. Most of the crust beneath the Illinois basin is modeled as one layer, with velocities up to 6.8 km/sec (Vs = 3.7 km/sec) at 37-km depth. The thick, high-velocity (Vp = 7.4 km/sec; Vs ~4.2 km/sec) lower crustal layer thins from about 20 km near New Madrid to about 6 km beneath the western Illinois basin. Refractions from the Moho and upper mantle occur as first arrivals over distances as a great as 160 km and reveal upper mantle layering to 60 km depth. Upper mantle layers with P-wave velocities of 8.2 km/sec (Vs = 4.5 km/sec) and 8.4 km/sec (Vs = 4.7 km/sec) are modeled at 43 and 60 km depth, respectively. Crustal Vp/Vs ratios range between 1.74 and 1.83, and upper mantle Vp/V s ratios range from 1.78 to 1.84. Poisson's ratios range from about 0.26 to 0.33 in the crust and from about 0.27 to 0.29 in the upper mantle. Modeled average densities range from about 2.55 in the sedimentary basins to 3.43 in the upper mantle. Geophysical characteristics of the crust and upper mantle within the New Madrid seismic zone are consistent with other continental rifts, but the crustal structure of the Illinois basin is not characteristics of most continental rift settings. Seismic and gravity data suggest a buried horst near the middle of Reelfoot rift, beneath which is a vertical zone of seismicity and velocity anomalies. The relative depth of the Reelfoot rift north and south of the Reelfoot graben suggests that the rift and its bounding faults may extend eastward beneath the city of Memphis.

Geologic evolution of the Kastel trough and its implications on the Adiyaman oil fields, SE Turkey

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

Coskun, Bu.

1990-05-01

Oil field developments of the Adiyaman area one of the main oil producing zones in southeast Turkey, have been highly influenced by geologic evolution of the Kastel trough which is situated in front of the suture zone between the Arabian and Anatolian plates. The Upper Cretaceous movements created many paleostructural trends in the Kastel trough where important dolomitic and porous reservoirs exist. The most important tectonic event, which appeared during the Upper Cretaceous movements, is the accumulation of the Kocali-Karadut ophiolitic complex, advancing from the north to the south in the Kastel trough, where heavy materials caused formation of amore » structural model favoring generation and migration and entrapment of oil in the reservoir rocks. Due to the presence of the Kocali-Karadut complex in the Kastel trough the following zones have been distinguished. (1) North Uplift Area. Situated under the allochthonous units, many thrust and reverse faults characterize this zone. The presence of paleohighs, where primary dolomites develop, allows the appearance of some oil fields in the region. This is the main future exploration zone in southeast Turkey. (2) Accumulation Area. Advancing from the north to the south, the allochthonous Kocali-Karadut complex filled the Kastel trough creating a deep graben whose flanks present generally normal faults. (3) Structural Belt. Important paleohighs constitute an exploration trend in this zone where dolomitic and porous carbonates contain actual oil fields. (4) South Accumulation Area. Distant from the Arabian-Anatolian suture zone, regional tectonics and sedimentology show this zone remained deeply buried during geologic time; good source rocks were deposited during the Cretaceous. (5) South Uplift Area. This area corresponds to the northern flank of the huge regional Mardin high in southeast Turkey where new oil fields have been discovered.« less

Calcareous nannofossil and ammonite integrated biostratigraphy across the Jurassic - Cretaceous boundary strata of the Kopanitsa composite section (West Srednogorie Unit, southwest Bulgaria)

NASA Astrophysics Data System (ADS)

Stoykova, Kristalina; Idakieva, Vyara; Ivanov, Marin; Reháková, Daniela

2018-04-01

Calcareous nannofossil, calpionellid and ammonite occurrences have been directly constrained across the Jurassic-Cretaceous boundary interval in the section of Kopanitsa, SW Bulgaria. This section reveals a continuous and expanded sedimentary record through the Upper Tithonian and Lower Berriasian, besides an excellent calcareous nannofossil and ammonite record. The topmost part of the NJT 16b and the base of NJT 17a nannofossil Subzones correspond to the ammonite Microcanthum / Transitorius Subzone. The major part of the NJT 17a Subzone equates to the Durangites spp. ammonite Zone, whereas the NJT 17b Subzone correlates to the lower part of the B. jacobi ammonite Zone. The NKT nannofossil Zone approximately corresponds to the upper part of the B. jacobi Zone and the NK-1 nannofossil Zone correlates at least to the lowest part of the T. occitanica Zone. The FOs of Nannoconus globulus minor, N. wintereri, N. kamptneri minor, N. steinmannii minor, N. kamptneri kamptneri and N. steinmannii steinmannii are confirmed as reliable bio-horizons for correlations in the Mediterranean Tethys area. The first occurrence of Nannoconus wintereri is regarded as an almost concomitant event with the first occurrence of Berriasella jacobi. We suggest it could be the most useful nannofossil proxy for approximating the base of the B. jacobi Zone. Rare, but relatively well preserved calpionellids and calcareous dinoflagellates together with microfacies analysis were used additionally for stratigraphical and palaeoenvironmental interpretations. The investigated sediments are typical for the steep slope of a steepened ramp, with accumulation of hemipelagic and gravitational deposits.

Propagation of back-arc extension into the arc lithosphere in the southern New Hebrides volcanic arc

NASA Astrophysics Data System (ADS)

Patriat, M.; Collot, J.; Danyushevsky, L.; Fabre, M.; Meffre, S.; Falloon, T.; Rouillard, P.; Pelletier, B.; Roach, M.; Fournier, M.

2015-09-01

New geophysical data acquired during three expeditions of the R/V Southern Surveyor in the southern part of the North Fiji Basin allow us to characterize the deformation of the upper plate at the southern termination of the New Hebrides subduction zone, where it bends eastward along the Hunter Ridge. Unlike the northern end of the Tonga subduction zone, on the other side of the North Fiji Basin, the 90° bend does not correspond to the transition from a subduction zone to a transform fault, but it is due to the progressive retreat of the New Hebrides trench. The subduction trench retreat is accommodated in the upper plate by the migration toward the southwest of the New Hebrides arc and toward the south of the Hunter Ridge, so that the direction of convergence remains everywhere orthogonal to the trench. In the back-arc domain, the active deformation is characterized by propagation of the back-arc spreading ridge into the Hunter volcanic arc. The N-S spreading axis propagates southward and penetrates in the arc, where it connects to a sinistral strike-slip zone via an oblique rift. The collision of the Loyalty Ridge with the New Hebrides arc, less than two million years ago, likely initiated this deformation pattern and the fragmentation of the upper plate. In this particular geodynamic setting, with an oceanic lithosphere subducting beneath a highly sheared volcanic arc, a wide range of primitive subduction-related magmas has been produced including adakites, island arc tholeiites, back-arc basin basalts, and medium-K subduction-related lavas.

Forage yield and nutritive value of turf bermudagrasses managed to simulate a horse pasture management scheme in the U.S. Upper Transition Zone

USDA-ARS?s Scientific Manuscript database

Turf-type bermudagrasses [Cynodon dactylon (Pers.) L.] with improved cold tolerance could have potential use in horse pastures of the U.S. upper south for minimizing the damage to grass stands in these pastures from heavy trampling; however, the nutritive values of these bermudagrasses are not known...

Study of internal gravity waves in the meteor zone

NASA Technical Reports Server (NTRS)

Gavrilov, N. M.

1987-01-01

An important component of the dynamical regime of the atmosphere at heights near 100 km are internal gravity waves (IGW) with periods from about 5 min to about 17.5 hrs which propagate from the lower atmospheric layers and are generated in the uppermost region of the atmosphere. As IGW propagate upwards, their amplitudes increase and they have a considerable effect on upper atmospheric processes: (1) they provide heat flux divergences comparable with solar heating; (2) they influence the gaseous composition and produce wave variations of the concentrations of gaseous components and emissions of the upper atmosphere; and (3) they cause considerable acceleration of the mean stream. It was concluded that the periods, wavelengths, amplitudes and velocities of IGW propagation in the meteor zone are now measured quite reliably. However, for estimating the influence of IGW on the thermal regime and the circulation of the upper atmosphere these parameters are not as important as the values of wave fluxes of energy, heat, moment and mass.

Changing palaeoenvironments and tetrapod populations in the Daptocephalus Assemblage Zone (Karoo Basin, South Africa) indicate early onset of the Permo-Triassic mass extinction

NASA Astrophysics Data System (ADS)

Viglietti, Pia A.; Smith, Roger M. H.; Rubidge, Bruce S.

2018-02-01

Important palaeoenvironmental differences are identified during deposition of the latest Permian Daptocephalus Assemblage Zone (DaAZ) of the South African Beaufort Group (Karoo Supergoup), which is also divided into a Lower and Upper subzone. A lacustrine floodplain facies association showing evidence for higher water tables and subaqueous conditions on the floodplains is present in Lower DaAZ. The change to well-drained floodplain facies association in the Upper DaAZ is coincident with a faunal turnover as evidenced by the last appearance of the dicynodont Dicynodon lacerticeps, the therocephalian Theriognathus microps, the cynodont Procynosuchus delaharpeae, and first appearance of the dicynodont Lystrosaurus maccaigi within the Ripplemead member. Considering the well documented 3-phased extinction of Karoo tetrapods during the Permo-Triassic Mass Extinction (PTME), the facies transition between the Lower and Upper DaAZ represents earlier than previously documented palaeoenvironmental changes associated with the onset of this major global biotic crisis.

Regional rainfall thresholds for landslide occurrence using a centenary database

NASA Astrophysics Data System (ADS)

Vaz, Teresa; Luís Zêzere, José; Pereira, Susana; Cruz Oliveira, Sérgio; Quaresma, Ivânia

2017-04-01

Rainfall is one of the most important triggering factors for landslides occurrence worldwide. The relation between rainfall and landslide occurrence is complex and some approaches have been focus on the rainfall thresholds identification, i.e., rainfall critical values that when exceeded can initiate landslide activity. In line with these approaches, this work proposes and validates rainfall thresholds for the Lisbon region (Portugal), using a centenary landslide database associated with a centenary daily rainfall database. The main objectives of the work are the following: i) to compute antecedent rainfall thresholds using linear and potential regression; ii) to define lower limit and upper limit rainfall thresholds; iii) to estimate the probability of critical rainfall conditions associated with landslide events; and iv) to assess the thresholds performance using receiver operating characteristic (ROC) metrics. In this study we consider the DISASTER database, which lists landslides that caused fatalities, injuries, missing people, evacuated and homeless people occurred in Portugal from 1865 to 2010. The DISASTER database was carried out exploring several Portuguese daily and weekly newspapers. Using the same newspaper sources, the DISASTER database was recently updated to include also the landslides that did not caused any human damage, which were also considered for this study. The daily rainfall data were collected at the Lisboa-Geofísico meteorological station. This station was selected considering the quality and completeness of the rainfall data, with records that started in 1864. The methodology adopted included the computation, for each landslide event, of the cumulative antecedent rainfall for different durations (1 to 90 consecutive days). In a second step, for each combination of rainfall quantity-duration, the return period was estimated using the Gumbel probability distribution. The pair (quantity-duration) with the highest return period was considered as the critical rainfall combination responsible for triggering the landslide event. Only events whose critical rainfall combinations have a return period above 3 years were included. This criterion reduces the likelihood of been included events whose triggering factor was other than rainfall. The rainfall quantity-duration threshold for the Lisbon region was firstly defined using the linear and potential regression. Considering that this threshold allow the existence of false negatives (i.e. events below the threshold) it was also identified the lower limit and upper limit rainfall thresholds. These limits were defined empirically by establishing the quantity-durations combinations bellow which no landslides were recorded (lower limit) and the quantity-durations combinations above which only landslides were recorded without any false positive occurrence (upper limit). The zone between the lower limit and upper limit rainfall thresholds was analysed using a probabilistic approach, defining the uncertainties of each rainfall critical conditions in the triggering of landslides. Finally, the performances of the thresholds obtained in this study were assessed using ROC metrics. This work was supported by the project FORLAND - Hydrogeomorphologic risk in Portugal: driving forces and application for land use planning [grant number PTDC/ATPGEO/1660/2014] funded by the Portuguese Foundation for Science and Technology (FCT), Portugal. Sérgio Cruz Oliveira is a post-doc fellow of the FCT [grant number SFRH/BPD/85827/2012].

Designing a network of critical zone observatories to explore the living skin of the terrestrial Earth

Treesearch

Susan L. Brantley; William H. McDowell; William E. Dietrich; Timothy S. White; Praveen Kumar; Suzanne P. Anderson; Jon Chorover; Kathleen Ann Lohse; Roger C. Bales; Daniel D. Richter; Gordon Grant; Jérôme Gaillardet

2017-01-01

The critical zone (CZ), the dynamic living skin of the Earth, extends from the top of the vegetative canopy through the soil and down to fresh bedrock and the bottom of the groundwater. All humans live in and depend on the CZ. This zone has three co-evolving surfaces: the top of the vegetative canopy, the ground surface, and a deep subsurface below which Earth’s...

The 2011 Tohoku-oki Earthquake related to a large velocity gradient within the Pacific plate

NASA Astrophysics Data System (ADS)

Matsubara, Makoto; Obara, Kazushige

2015-04-01

We conduct seismic tomography using arrival time data picked by the high sensitivity seismograph network (Hi-net) operated by National Research Institute for Earth Science and Disaster Prevention (NIED). We used earthquakes off the coast outside the seismic network around the source region of the 2011 Tohoku-oki Earthquake with the centroid depth estimated from moment tensor inversion by NIED F-net (broadband seismograph network) as well as earthquakes within the seismic network determined by Hi-net. The target region, 20-48N and 120-148E, covers the Japanese Islands from Hokkaido to Okinawa. A total of manually picked 4,622,346 P-wave and 3,062,846 S-wave arrival times for 100,733 earthquakes recorded at 1,212 stations from October 2000 to August 2009 is available for use in the tomographic method. In the final iteration, we estimate the P-wave slowness at 458,234 nodes and the S-wave slowness at 347,037 nodes. The inversion reduces the root mean square of the P-wave traveltime residual from 0.455 s to 0.187 s and that of the S-wave data from 0.692 s to 0.228 s after eight iterations (Matsubara and Obara, 2011). Centroid depths are determined using a Green's function approach (Okada et al., 2004) such as in NIED F-net. For the events distant from the seismic network, the centroid depth is more reliable than that determined by NIED Hi-net, since there are no stations above the hypocenter. We determine the upper boundary of the Pacific plate based on the velocity structure and earthquake hypocentral distribution. The upper boundary of the low-velocity (low-V) oceanic crust corresponds to the plate boundary where thrust earthquakes are expected to occur. Where we do not observe low-V oceanic crust, we determine the upper boundary of the upper layer of the double seismic zone within high-V Pacific plate. We assume the depth at the Japan Trench as 7 km. We can investigate the velocity structure within the Pacific plate such as 10 km beneath the plate boundary since the rays from the hypocenter around the coseismic region of the Tohoku-oki earthquake take off downward and pass through the Pacific plate. The landward low-V zone with a large anomaly corresponds to the western edge of the coseismic slip zone of the 2011 Tohoku-oki earthquake. The initial break point (hypocenter) is associated with the edge of a slightly low-V and low-Vp/Vs zone corresponding to the boundary of the low- and high-V zone. The trenchward low-V and low-Vp/Vs zone extending southwestward from the hypocenter may indicate the existence of a subducted seamount. The high-V zone and low-Vp/Vs zone might have accumulated the strain and resulted in the huge coseismic slip zone of the 2011 Tohoku earthquake. The low-V and low-Vp/Vs zone is a slight fluctuation within the high-V zone and might have acted as the initial break point of the 2011 Tohoku earthquake. Reference Matsubara, M. and K. Obara (2011) The 2011 Off the Pacific Coast of Tohoku earthquake related to a strong velocity gradient with the Pacific plate, Earth Planets Space, 63, 663-667. Okada, Y., K. Kasahara, S. Hori, K. Obara, S. Sekiguchi, H. Fujiwara, and A. Yamamoto (2004) Recent progress of seismic observation networks in Japan-Hi-net, F-net, K-NET and KiK-net, Research News Earth Planets Space, 56, xv-xxviii.

New data on microbiota of the Middle Volgian substage in the Loino Section (Kirov oblast)

NASA Astrophysics Data System (ADS)

Ustinova, M. A.; Tesakova, E. M.

2017-05-01

The calcareous nannoplankton was established for the first time in Upper Volgian deposits of the Loino Section (Kirov oblast). Here, single coccolites of representatives of genus Watznaueria of wide stratigraphic and geographic distributions dominate. Representatives of genus Zuegrhabdotus are less common, whereas species of genus Polypodorhabdus are rare. The taxonomic composition of the calcareous nannoplankton assemblage does not allow us to distinguish the nannoplankton zone in the Loino Section, but it gives us an idea about its distribution at the Volgian Stage in the Russian Plate. As corresponding microfauna, foraminifers, assigned to the Lenticulina infravolgaensis-Saracenaria pravoslavlevi Zone, and ostracods were identified to substantiate the age of host deposits. The ostracod assemblage is assigned to the Macrodentina (Polydentina) subtriangularis Beds established on the Volga River left bank in deposits corresponding to the ammonite zones Panderi and Virgatus assigned to the middle Volgian substage. On the basis of ostracods, the warm-water well-aerating environment of the upper sublittoral (as deep as 50 m) was reconstructed.

Detrital Cr-spinel in the Šambron-Kamenica Zone (Slovakia): evidence for an ocean-spreading zone in the Northern Vardar suture?

NASA Astrophysics Data System (ADS)

Lenaz, Davide; Mazzoli, Claudio; Spišiak, Jan; Princivalle, Francesco; Maritan, Lara

2009-03-01

The Šambron-Kamenica Zone is situated on the northern margin of the Levočské vrchy mountains and Šarišskà vrchovina Highland, where the Central Carpathian Paleogene joins the Pieniny Klippen Belt. Sandstone outcrops in this area. From Cretaceous to Late Oligocene in age, these sediments suggest transport directions from S and SE. The heavy mineral assemblages of this sandstone include Cr-spinel grains, mainly displaying types II and III alpine-peridotite affinities, and are representative of Ocean Island Basalt volcanism. A sample from Upper Eocene sediments at Vit’az shows a clear change in Cr-spinel composition, which turns out to have types I and II peridotite affinities, and to derive from arc and Middle Ocean Ridge Basalt volcanism, with sediment transport directions from SW and WSW. These data indicate major variations in the Upper Eocene tectonic setting, giving constraints to paleogeographic reconstruction of the Slovak Central Carpathians.

Hydrogeology at Air Force Plant 4 and vicinity and water quality of the Paluxy Aquifer, Fort Worth, Texas

USGS Publications Warehouse

Kuniansky, Eve L.; Jones, Sonya A.; Brock, Robert D.; Williams, M.D.

1996-01-01

Ground water in the surficial terrace alluvial aquifer is contaminated at Air Force Plant 4, Fort Worth, Texas, and at the adjacent Naval Air Station. Some of the contaminated water has leaked from the terrace alluvial aquifer to an uppermost interval of the Paluxy Formation (the Paluxy "upper sand") beneath the east parking lot, east of the assembly building, and to the upper and middle zones of the Paluxy aquifer near Bomber Road, west of the assembly building. Citizens are concerned that contaminants from the plant, principally trichloroethylene and chromium might enter nearby municipal and domestic wells that pump water from the middle and lower zones of the Paluxy aquifer. Geologic formations that crop out in the study area, from oldest to youngest, are the Paluxy Formation (aquifer), Walnut Formation (confining unit), and Goodland Limestone (confining unit). Beneath the Paluxy Formation is the Glen Rose Formation (confining unit) and Twin Mountains Formation (aquifer). The terrace alluvial deposits overlie these Cretaceous rocks. The terrace alluvial aquifer, which is not used for municipal water supply, is separated from the Paluxy aquifer by the Goodland-Walnut confining unit. The confining unit restricts the flow of ground water between these aquifers in most places; however, downward leakage to the Paluxy aquifer might occur through the "window," where the confining unit is thin or absent. The Paluxy aquifer is divided into upper, middle, and lower zones. The Paluxy "upper sand" underlying the "window" is an apparently isolated, mostly unsaturated, sandy lens within the uppermost part of the upper zone. The Paluxy aquifer is recharged by leakage from Lake Worth and by precipitation on the outcrop area. Discharge from the aquifer primarily occurs as pumpage from municipal and domestic wells. The Paluxy aquifer is separated from the underlying Twin Mountains aquifer by the Glen Rose confining unit. Water-level maps indicate that (1) ground water in the terrace alluvial aquifer appears to flow outward, away from Air Force Plant 4; (2) a ground-water mound, possibly caused by downward leakage from the terrace alluvial aquifer, is present in the Paluxy "upper sand" beneath the "window;" and (3) lateral ground-water flow in regionally extensive parts of the Paluxy aquifer is from west to east-southeast. Trichloroethylene concentrations at Air Force Plant 4 have ranged from about 10,000 to about 100,000 micrograms per liter in the terrace alluvial aquifer, from 8,000 to 11,000 micrograms per liter in the Paluxy "upper sand," and from 2 to 50 micrograms per liter in the upper and middle zones of the Paluxy aquifer. Chromium concentrations at Air Force Plant 4 have ranged from 0 to 629 micrograms per liter in the terrace alluvial aquifer. The seven municipal wells mostly west and south of Air Force Plant 4 are not along a flowpath for leakage of contaminants from the plant because ground-water flow in the Paluxy aquifer is toward the east-southeast. Furthermore, trichloroethylene was not detected in any of these wells in 1993 when all were sampled for water quality. The results of water-quality sampling at 10 domestic wells northwest of the Air Force Plant 4 during April 1993 and April 1995 indicated that neither trichloroethylene nor chromium had migrated off-site to these wells.

75 FR 55272 - Safety Zone; Mississippi River, Mile 212.0 to 214.5

Federal Register 2010, 2011, 2012, 2013, 2014

2010-09-10

...-AA00 Safety Zone; Mississippi River, Mile 212.0 to 214.5 AGENCY: Coast Guard, DHS. ACTION: Temporary... Mississippi River, Mile 212.0 to 214.5, extending West of Portage Island to the right descending bank of the... based fireworks display between mile 212.0 to 214.5 on the Upper Mississippi River. This event presents...

Aerobic Microbial Respiration In Oceanic Oxygen Minimum Zones.

PubMed

Kalvelage, Tim; Lavik, Gaute; Jensen, Marlene M; Revsbech, Niels Peter; Löscher, Carolin; Schunck, Harald; Desai, Dhwani K; Hauss, Helena; Kiko, Rainer; Holtappels, Moritz; LaRoche, Julie; Schmitz, Ruth A; Graco, Michelle I; Kuypers, Marcel M M

2015-01-01

Oxygen minimum zones are major sites of fixed nitrogen loss in the ocean. Recent studies have highlighted the importance of anaerobic ammonium oxidation, anammox, in pelagic nitrogen removal. Sources of ammonium for the anammox reaction, however, remain controversial, as heterotrophic denitrification and alternative anaerobic pathways of organic matter remineralization cannot account for the ammonium requirements of reported anammox rates. Here, we explore the significance of microaerobic respiration as a source of ammonium during organic matter degradation in the oxygen-deficient waters off Namibia and Peru. Experiments with additions of double-labelled oxygen revealed high aerobic activity in the upper OMZs, likely controlled by surface organic matter export. Consistently observed oxygen consumption in samples retrieved throughout the lower OMZs hints at efficient exploitation of vertically and laterally advected, oxygenated waters in this zone by aerobic microorganisms. In accordance, metagenomic and metatranscriptomic analyses identified genes encoding for aerobic terminal oxidases and demonstrated their expression by diverse microbial communities, even in virtually anoxic waters. Our results suggest that microaerobic respiration is a major mode of organic matter remineralization and source of ammonium (~45-100%) in the upper oxygen minimum zones, and reconcile hitherto observed mismatches between ammonium producing and consuming processes therein.

Aerobic Microbial Respiration In Oceanic Oxygen Minimum Zones

PubMed Central

Kalvelage, Tim; Lavik, Gaute; Jensen, Marlene M.; Revsbech, Niels Peter; Löscher, Carolin; Schunck, Harald; Desai, Dhwani K.; Hauss, Helena; Kiko, Rainer; Holtappels, Moritz; LaRoche, Julie; Schmitz, Ruth A.; Graco, Michelle I.; Kuypers, Marcel M. M.

2015-01-01

Oxygen minimum zones are major sites of fixed nitrogen loss in the ocean. Recent studies have highlighted the importance of anaerobic ammonium oxidation, anammox, in pelagic nitrogen removal. Sources of ammonium for the anammox reaction, however, remain controversial, as heterotrophic denitrification and alternative anaerobic pathways of organic matter remineralization cannot account for the ammonium requirements of reported anammox rates. Here, we explore the significance of microaerobic respiration as a source of ammonium during organic matter degradation in the oxygen-deficient waters off Namibia and Peru. Experiments with additions of double-labelled oxygen revealed high aerobic activity in the upper OMZs, likely controlled by surface organic matter export. Consistently observed oxygen consumption in samples retrieved throughout the lower OMZs hints at efficient exploitation of vertically and laterally advected, oxygenated waters in this zone by aerobic microorganisms. In accordance, metagenomic and metatranscriptomic analyses identified genes encoding for aerobic terminal oxidases and demonstrated their expression by diverse microbial communities, even in virtually anoxic waters. Our results suggest that microaerobic respiration is a major mode of organic matter remineralization and source of ammonium (~45-100%) in the upper oxygen minimum zones, and reconcile hitherto observed mismatches between ammonium producing and consuming processes therein. PMID:26192623

Acid precipitation: compositional changes during throughfall; soil water. Technical completion report

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

Klein, R.

1984-12-01

Lysimeters were installed at two soil depths within each of the three major ecosystems on Camels Hump Mountain. Collections were made weekly during the frost-free season of 1982 and 1983. Samples were analyzed for pH, conductivity, and a broad range of metals, anionic and cationic constituents, and for other physical properties. The findings included: soil solutions obtained from the upper-elevations in a northern coniferous forest zone are significantly more acidic than those from the lower elevation hardwood forest zone; soil solutions for all ecological zones are more acidic in the spring during and shortly after snowmelt than they are latermore » in the frost free-season; aluminum in soil solutions from the upper elevations is present in concentrations known to be phytotoxic to seedlings of forest trees and to groundcover plants; cadmium, Pb, and Zn are, in the spring, present in concentrations that are close to being phytotoxic; there are changes in the ratios of divalent cations to specific metals during the season and as functions of altitude and forest zones; nitrate concentration in soil water are also elevation- and time dependent.« less

High resolution image of uppermost mantle beneath NE Iran continental collision zone

NASA Astrophysics Data System (ADS)

Motaghi, K.; Tatar, M.; Shomali, Z. H.; Kaviani, A.; Priestley, K.

2012-10-01

We invert 3775 relative P wave arrival times using the ACH damped least square method of Aki et al. (1977) to study upper mantle structure beneath the NE Iran continental collision zone. The data for this study were recorded by 17 three component broad-band stations operated from August 2006 to February 2008 along a profile from the center of Iranian Plateau, near Yazd, to the northeastern part of Iran on the Turan Platform just north of the Kopeh Dagh Mountains. The results confirm the previously known low velocity upper mantle beneath Central Iran. Our tomographic model reveals a deep high velocity anomaly. The surficial expressions of this anomaly are between the Ashkabad and Doruneh Faults, where the resolution and ray coverage are good. A transition zone in uppermost mantle is recognized under the Binalud foreland that we interpreted as suture zone between Iran and Turan platform. Our results indicate that Atrak Valley which is the boundary between the Binalud and Kopeh Dagh Mountains can be considered as the northeastern suture of the Iranian Plateau where Eurasia and Turan Platform under-thrust beneath the Binalud range and Central Iran.

Reanalysis of water and carbon cycle models at a critical zone observatory

USDA-ARS?s Scientific Manuscript database

The Susquehanna Shale Hills Critical Zone Observatory (SSHCZO) is a forested, hill-slope catchment located in the temperate-climate of central Pennsylvania with an extensive network of ground-based instrumentation for model testing and development. In this paper we discuss the use of multi-state fi...

Anatomy of the dead sea transform from lithospheric to microscopic scale

USGS Publications Warehouse

Weber, M.; Abu-Ayyash, K.; Abueladas, A.; Agnon, A.; Alasonati-Tasarova, Z.; Al-Zubi, H.; Babeyko, A.; Bartov, Y.; Bauer, K.; Becken, M.; Bedrosian, P.A.; Ben-Avraham, Z.; Bock, G.; Bohnhoff, M.; Bribach, J.; Dulski, P.; Ebbing, J.; El-Kelani, R.; Forster, A.; Forster, H.-J.; Frieslander, U.; Garfunkel, Z.; Goetze, H.J.; Haak, V.; Haberland, C.; Hassouneh, M.; Helwig, S.; Hofstetter, A.; Hoffmann-Rotrie, A.; Jackel, K.H.; Janssen, C.; Jaser, D.; Kesten, D.; Khatib, M.; Kind, R.; Koch, O.; Koulakov, I.; Laske, Gabi; Maercklin, N.; Masarweh, R.; Masri, A.; Matar, A.; Mechie, J.; Meqbel, N.; Plessen, B.; Moller, P.; Mohsen, A.; Oberhansli, R.; Oreshin, S.; Petrunin, A.; Qabbani, I.; Rabba, I.; Ritter, O.; Romer, R.L.; Rumpker, G.; Rybakov, M.; Ryberg, T.; Saul, J.; Scherbaum, F.; Schmidt, S.; Schulze, A.; Sobolev, S.V.; Stiller, M.; Stromeyer, D.; Tarawneh, K.; Trela, C.; Weckmann, U.; Wetzel, U.; Wylegalla, K.

2009-01-01

Fault zones are the locations where motion of tectonic plates, often associated with earthquakes, is accommodated. Despite a rapid increase in the understanding of faults in the last decades, our knowledge of their geometry, petrophysical properties, and controlling processes remains incomplete. The central questions addressed here in our study of the Dead Sea Transform (DST) in the Middle East are as follows: (1) What are the structure and kinematics of a large fault zone? (2) What controls its structure and kinematics? (3) How does the DST compare to other plate boundary fault zones? The DST has accommodated a total of 105 km of leftlateral transform motion between the African and Arabian plates since early Miocene (???20 Ma). The DST segment between the Dead Sea and the Red Sea, called the Arava/ Araba Fault (AF), is studied here using a multidisciplinary and multiscale approach from the ??m to the plate tectonic scale. We observe that under the DST a narrow, subvertical zone cuts through crust and lithosphere. First, from west to east the crustal thickness increases smoothly from 26 to 39 km, and a subhorizontal lower crustal reflector is detected east of the AF. Second, several faults exist in the upper crust in a 40 km wide zone centered on the AF, but none have kilometer-size zones of decreased seismic velocities or zones of high electrical conductivities in the upper crust expected for large damage zones. Third, the AF is the main branch of the DST system, even though it has accommodated only a part (up to 60 km) of the overall 105 km of sinistral plate motion. Fourth, the AF acts as a barrier to fluids to a depth of 4 km, and the lithology changes abruptly across it. Fifth, in the top few hundred meters of the AF a locally transpressional regime is observed in a 100-300 m wide zone of deformed and displaced material, bordered by subparallel faults forming a positive flower structure. Other segments of the AF have a transtensional character with small pull-aparts along them. The damage zones of the individual faults are only 5-20 m wide at this depth range. Sixth, two areas on the AF show mesoscale to microscale faulting and veining in limestone sequences with faulting depths between 2 and 5 km. Seventh, fluids in the AF are carried downward into the fault zone. Only a minor fraction of fluids is derived from ascending hydrothermal fluids. However, we found that on the kilometer scale the AF does not act as an important fluid conduit. Most of these findings are corroborated using thermomechanical modeling where shear deformation in the upper crust is localized in one or two major faults; at larger depth, shear deformation occurs in a 20-40 km wide zone with a mechanically weak decoupling zone extending subvertically through the entire lithosphere. Copyright 2009 by the American Geophysical Union.

Magnetotelluric Imaging of the Lithosphere Across the Variscan Orogen (Iberian Autochthonous Domain, NW Iberia)

NASA Astrophysics Data System (ADS)

Alves Ribeiro, J.; Monteiro-Santos, F. A.; Pereira, M. F.; Díez Fernández, R.; Dias da Silva, Í.; Nascimento, C.; Silva, J. B.

2017-12-01

A new magnetotelluric (MT) survey comprising 17 MT soundings throughout a 30 km long N30°W transect in the Iberian autochthons domain of NW Iberia (Central Iberian Zone) is presented. The 2-D inversion model shows the resistivity structure of the continental crust up to 10 km depth, heretofore unavailable for this region of the Variscan Orogen. The MT model reveals a wavy structure separating a conductive upper layer underlain by a resistive layer, thus picturing the two main tectonic blocks of a large-scale D2 extensional shear zone (i.e., Pinhel shear zone). The upper layer represents a lower grade metamorphic domain that includes graphite-rich rocks. The lower layer consists of high-grade metamorphic rocks that experienced partial melting and are associated with granites (more resistive) emplaced during crustal thinning. The wavy structure is the result of superimposed crustal shortening responsible for the development of large-scale D3 folds (e.g., Marofa synform), later deflected and refolded by a D4 strike-slip shear zone (i.e., Juzbado-Penalva do Castelo shear zone). The later contribution to the final structure of the crust is marked by the intrusion of postkinematic granitic rocks and the propagation of steeply dipping brittle fault zones. Our study demonstrates that MT imaging is a powerful tool to understand complex crustal structures of ancient orogens in order to design future prospecting surveys for mineral deposits of economic interest.

Considerations for Assessing Maximum Critical Temperatures in Small Ectothermic Animals: Insights from Leaf-Cutting Ants

PubMed Central

Ribeiro, Pedro Leite; Camacho, Agustín; Navas, Carlos Arturo

2012-01-01

The thermal limits of individual animals were originally proposed as a link between animal physiology and thermal ecology. Although this link is valid in theory, the evaluation of physiological tolerances involves some problems that are the focus of this study. One rationale was that heating rates shall influence upper critical limits, so that ecological thermal limits need to consider experimental heating rates. In addition, if thermal limits are not surpassed in experiments, subsequent tests of the same individual should yield similar results or produce evidence of hardening. Finally, several non-controlled variables such as time under experimental conditions and procedures may affect results. To analyze these issues we conducted an integrative study of upper critical temperatures in a single species, the ant Atta sexdens rubropiosa, an animal model providing large numbers of individuals of diverse sizes but similar genetic makeup. Our specific aims were to test the 1) influence of heating rates in the experimental evaluation of upper critical temperature, 2) assumptions of absence of physical damage and reproducibility, and 3) sources of variance often overlooked in the thermal-limits literature; and 4) to introduce some experimental approaches that may help researchers to separate physiological and methodological issues. The upper thermal limits were influenced by both heating rates and body mass. In the latter case, the effect was physiological rather than methodological. The critical temperature decreased during subsequent tests performed on the same individual ants, even one week after the initial test. Accordingly, upper thermal limits may have been overestimated by our (and typical) protocols. Heating rates, body mass, procedures independent of temperature and other variables may affect the estimation of upper critical temperatures. Therefore, based on our data, we offer suggestions to enhance the quality of measurements, and offer recommendations to authors aiming to compile and analyze databases from the literature. PMID:22384147

Superconductivity induced by In substitution into the topological crystalline insulator Pb0.5Sn0.5Te

NASA Astrophysics Data System (ADS)

Zhong, R. D.; Schneeloch, J. A.; Liu, T. S.; Camino, F. E.; Tranquada, J. M.; Gu, G. D.

2014-07-01

Indium substitution turns the topological crystalline insulator (TCI) Pb0.5Sn0.5Te into a possible topological superconductor. To investigate the effect of the indium concentration on the crystal structure and superconducting properties of (Pb0.5Sn0.5)1-xInxTe, we have grown high-quality single crystals using a modified floating-zone method and have performed systematic studies for indium content in the range 0≤x≤0.35. We find that the single crystals retain the rocksalt structure up to the solubility limit of indium (x ˜0.30). Experimental dependencies of the superconducting transition temperature (Tc) and the upper critical magnetic field (Hc2) on the indium content x have been measured. The maximum Tc is determined to be 4.7 K at x =0.30, with μ0Hc2(T =0)≈5 T.

Potential impacts of the Deepwater Horizon oil spill on large pelagic fishes

NASA Astrophysics Data System (ADS)

Frias-Torres, Sarrah; Bostater, Charles R., Jr.

2011-11-01

Biogeographical analyses provide insights on how the Deepwater Horizon oil spill impacted large pelagic fishes. We georeferenced historical ichthyoplankton surveys and published literature to map the spawning and larval areas of bluefin tuna, swordfish, blue marlin and whale shark sightings in the Gulf of Mexico with daily satellite-derived images detecting surface oil. The oil spill covered critical areas used by large pelagic fishes. Surface oil was detected in 100% of the northernmost whale shark sightings, in 32.8 % of the bluefin tuna spawning area and 38 % of the blue marlin larval area. No surface oil was detected in the swordfish spawning and larval area. Our study likely underestimates the extend of the oil spill due to satellite sensors detecting only the upper euphotic zone and the use of dispersants altering crude oil density, but provides a previously unknown spatio-temporal analysis.

Groundwater vulnerability mapping in Guadalajara aquifers system (Western Mexico)

NASA Astrophysics Data System (ADS)

Rizo-Decelis, L. David; Marín, Ana I.; Andreo, Bartolomé

2016-04-01

Groundwater vulnerability mapping is a practical tool to implement strategies for land-use planning and sustainable socioeconomic development coherent with groundwater protection. The objective of vulnerability mapping is to identify the most vulnerable zones of catchment areas and to provide criteria for protecting the groundwater used for drinking water supply. The delineation of protection zones in fractured aquifers is a challenging task due to the heterogeneity and anisotropy of hydraulic conductivities, which makes difficult prediction of groundwater flow organization and flow velocities. Different methods of intrinsic groundwater vulnerability mapping were applied in the Atemajac-Toluquilla groundwater body, an aquifers system that covers around 1300 km2. The aquifer supplies the 30% of urban water resources of the metropolitan area of Guadalajara (Mexico), where over 4.6 million people reside. Study area is located in a complex neotectonic active volcanic region in the Santiago River Basin (Western Mexico), which influences the aquifer system underneath the city. Previous works have defined the flow dynamics and identified the origin of recharge. In addition, the mixture of fresh groundwater with hydrothermal and polluted waters have been estimated. Two main aquifers compose the multilayer system. The upper aquifer is unconfined and consists of sediments and pyroclastic materials. Recharge of this aquifer comes from rainwater and ascending vertical fluids from the lower aquifer. The lower aquifer consists of fractured basalts of Pliocene age. Formerly, the main water source has been the upper unit, which is a porous and unconsolidated unit, which acts as a semi-isotropic aquifer. Intense groundwater usage has resulted in lowering the water table in the upper aquifer. Therefore, the current groundwater extraction is carried out from the deeper aquifer and underlying bedrock units, where fracture flow predominates. Pollution indicators have been reported in some monitoring wells, which have been related to anthropogenic activity. Vulnerability maps were produced using different parametric methods (e.g.: DRASTIC, GOD, DISCO, AVI), then the results are compared and assessed. Since each one of these methods use different number of parameters and weights, relatively different results were obtained, although the results have been evaluated with common cartographic inputs. The comparison between selected methods shows that the GOD method results are more correlated with the other methods and produces vulnerability maps comparable with them. Even though groundwater vulnerability is a critical issue around the world, no protection zones have been delineated in Guadalajara city, one of the biggest in Latin America. The groundwater contamination in the study area poses a serious risk for a large population and the environment. This work aims to propose an approach for groundwater protection cartography, based on the application and the comparison of results from different contamination vulnerability methods. These outcomes may assist water authorities to identify the higher vulnerable zones of the aquifers, in order to improving and adapting the land planning and management according to the protection of the own water resources.

Reconciling Pre- and Co-Seismic Deformation at Megathrusts: Tohoku Informing Cascadia

NASA Astrophysics Data System (ADS)

Furlong, K. P.; Govers, R. M.

2013-12-01

One of the outstanding goals of earthquake science is to effectively anticipate the earthquake characteristics of a future event - magnitude, rupture area, slip history - through the judicious application of models that use observations of inter-earthquake deformation and the history of earthquakes along that plate boundary segment. The series of great earthquakes over the past decade since the 2004 Mw 9.2 Sumatra earthquake have demonstrated both the sobering reality that our current models of subduction zone earthquake genesis are insufficient but more positively have provided a wealth of data and observations that can be used to develop improved framework models of the lithospheric behavior through the earthquake cycle in subduction zones. Some of the issues that recent observations raise are straightforward, while others imply aspects of the subduction process that have not been previously considered important. Based on observations of a range of great earthquakes since 2004, and with a particular focus on the 2011 Mw 9.0 Tohoku event we can identify a suite of key issues that include: (1) Patterns of inter-seismic deformation (strain accumulation) are not simply the converse of the co-seismic elastic strain release. (2) Deformation of the slab during the earthquake cycle is a common occurrence and its role in buffering upper-plate deformation is a key consideration in the potential tsunamigenic character of a subduction system. (3) Rates of pre-earthquake deformation (e.g. observed upper-plate GPS displacements) and inferred slip deficit accumulation on the megathrust are inconsistent with co-seismic displacements/fault slip and recurrence intervals. (4) Patterns of megathrust locked patches, degrees of coupling and other parameterizations that are used to define earthquake potential have only a loose agreement with the actual patterns of slip and moment release seen in the ensuing great earthquake. Simple elastic models do provide a general agreement between processes along the megathrust and observations regionally - i.e. with such models (e.g. Okada-type solutions) we find reasonable agreement among geodetic and seismologic models. In assessing sensitivities in our preliminary modeling, we find that depending on the strength and rheologic considerations in the model, similar patterns of displacement in the upper plate in the typical observing zones (on-shore, ~ 100+ km from trench) can have significantly different displacement effects in the vicinity of the earthquake rupture and trench - the areas most critical to tsunamigenesis and assessing earthquake magnitude. Also although it is perhaps reassuring to see that there is general agreement between the seismologically determined finite fault models (FFM) and the observed surface deformation; this information after-the-fact does not tell us why the slip deficit accumulated as it did. Here we report on improved (numerical) models of the strain accumulation and release cycle in megathrust zones that better incorporate variations in rheology, the effects of plate boundary character (pre- and co-seismic), and the relationships between pre-earthquakes observed deformation and co-seismic rupture characteristics.

Plate boundary and major fault system in the overriding plate within the Shumagin gap at the Alaska-Aleutian subduction zone

NASA Astrophysics Data System (ADS)

Becel, A.; Shillington, D. J.; Nedimovic, M. R.; Keranen, K. M.; Li, J.; Webb, S. C.; Kuehn, H.

2013-12-01

Structure in the overriding plate is one of the parameters that may increase the tsunamigenic potential of a subduction zone but also influence the seismogenic behavior and segmentation of great earthquake rupture. The Alaska-Aleutian margin is characterized by along-strike changes in plate interface coupling over relatively small distances. Here, we present trench normal multichannel seismic (MCS) profiles acquired across the Shumagin gap that has not broken in many decades and appears to be weakly coupled. The high fold, deep penetration (636 channel, 8-km long streamer, 6600 cu.in airgun source) MCS data were acquired as part of the ALEUT project. This dataset gives us critical new constraints on the interplate boundary that can be traced over ~100 km distance beneath the forearc with high variation in its reflection response with depth. These profiles also reveal the detailed upper plate fault structure and forearc morphology. Clear reflections in the overriding plate appear to delineate one or more large faults that cross the shelf and the upper slope. These faults are observed 75 km back from the trench and seem to branch at depth and connect to the plate interface within this gap at ~11 s twtt. We compare the reflective structure of these faults to that of the plate boundary and examine where it intersects the megathrust with respect of the expected downdip limit of coupling. We also compare this major structure with the seismicity recorded in this sector. The imaged fault system is associated with a large deep basin (~6s twt) that is an inherited structure formed during the pre-Aleutian period. Basins faults appear to have accommodated primarily normal motion, although folding of sediments near the fault and complicated fault geometries in the shallow section may indicate that this fault has accommodated other types of motion during its history that may reflect the stress-state at the megathrust over time. The deformation within the youngest sediment also suggests also that this fault system might be still active. The coincident wide-angle seismic data coincident with one MCS profile allow the addition of more information about the deep P-wave velocity structure whereas the streamer tomography (Michaelson-Rotermund et al., this session) around the fault system add more detailed view into the complex structure in the shallow portions (upper 2km) of these structures showing a low velocity zone along one large fault suggesting that this fault is still active. These large-scale structures imaged in the overriding plate within the Shumagin gap are probably sufficiently profound to play a major role in the behavior of the megathrust in this area, segmentation of great earthquake rupture area, tsunami generation and may influence the frictional properties of the seismogenic zone at depth.

From orogenic buildup to extensional unroofing: the evolution of the Adria - Europe collisional zone in the Medvednica Mountains of Croatia

NASA Astrophysics Data System (ADS)

Beniest, Anouk; van Gelder, Inge; Matenco, Liviu; Willingshofer, Ernst; Gruic, Andrea; Tomljenovic, Bruno

2013-04-01

Quantifying the kinematics of the Miocene extension in the Pannonian Basin is of critical importance for understanding the evolution of Adria-Europe collision in particular in the transitional zone from the Alps (Adria the upper plate) to the Dinarides (Adria the lower plate). Recent studies have demonstrated that large-scale extensional unroofing and core-complex formation affected the Europe-Adria contact in the Dinarides during Miocene times. The relationship between this extensional exhumation of Adriatic units and the roughly coeval Miocene extension affecting the Alpine-derived units during their E-ward extrusion into the intra-Carpathians ALCAPA block and the formation of the Pannonian basin is still unknown. One key area situated in the transitional zone is the Medvednica Mountains of Croatia, an area that benefits from already existing and extensive petrological and structural studies. The area of the Medvednica Mountains has been targeted by the means of a field kinematic analysis complemented by low-temperature thermochronology, metamorphic petrology and sedimentological observations. The results demonstrate that two units, reflecting distinct Adriatic paleogeographical positions, make up the structural geometry of the mountains. The upper unit contains Paleozoic mostly fine clastic sequence metamorphosed in sub-greenschist facies, overlain by a proximal Adriatic facies consisting of Triassic shallow water carbonates. The lower unit is made up by a volcanic sequence overlain by gradual deepening Triassic carbonates metamorphosed in greenschist facies that bears a strong resemblance to the Triassic break-up volcanism and subsequent sedimentation affecting the distal Adriatic units observed elsewhere in the Jadar-Kopaonik unit of the Dinarides. The strong contrast between the Middle-Upper Triassic facies suggests large scale thrusting during Cretaceous nappe stacking. Subsequently, the studied area has been affected by significant extensional deformation creating the present-day turtleback geometry. This resulted in the formation of brittle normal faults in both units, locally tilted by the uplift of the mountain core, which indicate mostly NE-SW extension. The lower unit is affected by a pervasive deformation characterized by a wide mylonitic shear zone with stretching lineations indicating consistently top-NE to E sense of shear. The present-day structural geometry of the mountains was established during the Pliocene-Quaternary inversion. The exact ages of nappe-stacking and subsequent extensional exhumation will be clarified by the upcoming low-temperature thermochronology and absolute age dating study. However, available results demonstrate that the extensional geometry and sense of shear is typical for the Miocene extensional exhumation and basin formation that affected the Adria-Europe contact elsewhere in the Dinarids, e.g. Kozara-Prosara-Motajica and Fruska Gora extensional structures. By comparing similar extensional features observed in for instance the Rechnitz and Pohorje extensional structures, the combined study potentially demonstrates that the Miocene mechanism of extension and sense of shear is structurally coherent at the scale of the entire Dinaridic and Alpine margins.

Evaluation of pediatric upper extremity peripheral nerve injuries.

PubMed

Ho, Emily S

2015-01-01

The evaluation of motor and sensory function of the upper extremity after a peripheral nerve injury is critical to diagnose the location and extent of nerve injury as well as document functional recovery in children. The purpose of this paper is to describe an approach to the evaluation of the pediatric upper extremity peripheral nerve injuries through a critical review of currently used tests of sensory and motor function. Outcome studies on pediatric upper extremity peripheral nerve injuries in the Medline database were reviewed. The evaluation of the outcome in children less than 10 years of age with an upper extremity peripheral nerve injury includes careful observation of preferred prehension patterns, examination of muscle atrophy and sudomotor function, provocative tests, manual muscle testing and tests of sensory threshold and tactile gnosis. The evaluation of outcome in children with upper extremity peripheral nerve injuries warrants a unique approach. Copyright © 2015 Hanley & Belfus. Published by Elsevier Inc. All rights reserved.

Effects of aquifer heterogeneity on ground-water flow and chloride concentrations in the Upper Floridan aquifer near and within an active pumping well field, west-central Florida

USGS Publications Warehouse

Tihansky, A.B.

2005-01-01

Chloride concentrations have been increasing over time in water from wells within and near the Eldridge-Wilde well field, near the coast in west-central Florida. Variable increases in chloride concentrations from well to well over time are the combined result of aquifer heterogeneity and ground-water pumping within the Upper Floridan aquifer. Deep mineralized water and saline water associated with the saltwater interface appear to move preferentially along flow zones of high transmissivity in response to ground-water withdrawals. The calcium-bicarbonate-type freshwater of the Upper Floridan aquifer within the study area is variably enriched with ions by mixing with introduced deep and saline ground water. The amount and variability of increases in chloride and sulfate concentrations at each well are related to well location, depth interval, and permeable intervals intercepted by the borehole. Zones of high transmissivity characterize the multilayered carbonate rocks of the Upper Floridan aquifer. Well-developed secondary porosity within the Tampa/Suwannee Limestones and the Avon Park Formation has created producing zones within the Upper Floridan aquifer. The highly transmissive sections of the Avon Park Formation generally are several orders of magnitude more permeable than the Tampa/Suwannee Limestones, but both are associated with increased ground-water flow. The Ocala Limestone is less permeable and is dominated by primary, intergranular porosity. Acoustic televiewer logging, caliper logs, and borehole flow logs (both electromagnetic and heat pulse) indicate that the Tampa/Suwannee Limestone units are dominated by porosity owing to dissolution between 200 and 300 feet below land surface, whereas the porosity of the Avon Park Formation is dominated by fractures that occur primarily from 600 to 750 feet below land surface and range in angle from horizontal to near vertical. Although the Ocala Limestone can act as a semiconfining unit between the Avon Park Formation and the Tampa/Suwannee Limestones, seismic-reflection data and photolinear analyses indicate that fractures and discontinuities in the Ocala Limestone are present within the southwestern part of the well field. It is possible that some fracture zones extend upward from the Avon Park Formation through the Ocala, Suwannee, and Tampa Limestones to land surface. These fractures may provide a more direct hydrologic connection between transmissive zones that are vertically separated by less permeable stratigraphic units. Ground water moves along permeable zones within the Upper Floridan aquifer in response to changes in head gradients as a result of pumping. Borehole geophysical measurements, including flow logs, specific conductance logs, and continuous monitoring of specific conductance at selected fixed depths, indicate that borehole specific conductance varies substantially with time and in response to pumping stresses. Ground-water mixing between hydrogeologic units likely occurs along highly transmissive zones and within boreholes of active production wells. Ground-water movement and water-quality changes were greatest along the most transmissive zones. Variable mixing of three water-type end members (freshwater, deepwater, and saltwater) occurs throughout the study area. Both deepwater and saltwater are likely sources for elevated chloride and sulfate concentrations in ground water. Mass-balance calculations of mixtures of the three end members indicate that deepwater is found throughout the aquifer units. Samples from wells within the southwestern part of the well field indicate that deepwater migrates into the shallow permeable units in the southwestern part of the well field. Deepwater contributes to elevated sulfate and chloride concentrations, which increase with depth and are elevated in wells less than 400 feet deep. The greatest increases in chloride concentrations over time are found in water from wells closest to the saltwater interface. Gro

Critical Two-Point Function for Long-Range O( n) Models Below the Upper Critical Dimension

NASA Astrophysics Data System (ADS)

Lohmann, Martin; Slade, Gordon; Wallace, Benjamin C.

2017-12-01

We consider the n-component |φ|^4 lattice spin model (n ≥ 1) and the weakly self-avoiding walk (n=0) on Z^d, in dimensions d=1,2,3. We study long-range models based on the fractional Laplacian, with spin-spin interactions or walk step probabilities decaying with distance r as r^{-(d+α )} with α \\in (0,2). The upper critical dimension is d_c=2α . For ɛ >0, and α = 1/2 (d+ɛ ), the dimension d=d_c-ɛ is below the upper critical dimension. For small ɛ , weak coupling, and all integers n ≥ 0, we prove that the two-point function at the critical point decays with distance as r^{-(d-α )}. This "sticking" of the critical exponent at its mean-field value was first predicted in the physics literature in 1972. Our proof is based on a rigorous renormalisation group method. The treatment of observables differs from that used in recent work on the nearest-neighbour 4-dimensional case, via our use of a cluster expansion.

Crustal structure in Tengchong Volcano-Geothermal Area, western Yunnan, China

NASA Astrophysics Data System (ADS)

Wang, Chun-Yong; Huangfu, Gang

2004-02-01

Based upon the deep seismic sounding profiles carried out in the Tengchong Volcano-Geothermal Area (TVGA), western Yunnan Province of China, a 2-D crustal P velocity structure is obtained by use of finite-difference inversion and forward travel-time fitting method. The crustal model shows that a low-velocity anomaly zone exists in the upper crust, which is related to geothermal activity. Two faults, the Longling-Ruili Fault and Tengchong Fault, on the profile extend from surface to the lower crust and the Tengchong Fault likely penetrates the Moho. Moreover, based on teleseismic receiver functions on a temporary seismic network, S-wave velocity structures beneath the geothermal field show low S-wave velocity in the upper crust. From results of geophysical survey, the crust of TVGA is characterized by low P-wave and S-wave velocities, low resistivity, high heat-flow value and low Q. The upper mantle P-wave velocity is also low. This suggests presence of magma in the crust derived from the upper mantle. The low-velocity anomaly in upper crust may be related to the magma differentiation. The Tengchong volcanic area is located on the northeast edge of the Indian-Eurasian plate collision zone, away from the eastern boundary of the Indian plate by about 450 km. Based on the results of this paper and related studies, the Tengchong volcanoes can be classified as plate boundary volcanoes.

Thermal metamorphism of the Arunachal Himalaya, India: Raman thermometry and thermochronological constraints on the tectono-thermal evolution

NASA Astrophysics Data System (ADS)

Mathew, George; De Sarkar, Sharmistha; Pande, Kanchan; Dutta, Suryendu; Ali, Shakir; Rai, Apritam; Netrawali, Shilpa

2013-09-01

Determination of the peak thermal condition is vital in order to understand tectono-thermal evolution of the Himalayan belt. The Lesser Himalayan Sequence (LHS) in the Western Arunachal Pradesh, being rich in carbonaceous material (CM), facilitates the determination of peak metamorphic temperature based on Raman spectroscopy of carbonaceous material (RSCM). In this study, we have used RSCM method of Beyssac et al. (J Metamorph Geol 20:859-871, 2002a) and Rahl et al. (Earth Planet Sci Lett 240:339-354, 2005) to estimate the thermal history of LHS and Siwalik foreland from the western Arunachal Pradesh. The study indicates that the temperature of 700-800 °C in the Greater Himalayan Sequence (GHS) decreases to 650-700 °C in the main central thrust zone (MCTZ) and decreases further to <200 °C in the Mio-Pliocene sequence of Siwaliks. The work demonstrates greater reliability of Rahl et al.'s (Earth Planet Sci Lett 240:339-354, 2005) RSCM method for temperatures >600 and <340 °C. We show that the higher and lower zones of Bomdila Gneiss (BG) experienced temperature of ~600 °C and exhumed at different stages along the Bomdila Thrust (BT) and Upper Main Boundary Thrust (U.MBT). Pyrolysis analysis of the CM together with the Fission Track ages from upper Siwaliks corroborates the RSCM thermometry estimate of ~240 °C. The results indicate that the Permian sequence north of Lower MBT was deposited at greater depths (>12 km) than the upper Siwalik sediments to its south at depths <8 km before they were exhumed. The 40Ar/39Ar ages suggest that the upper zones of Se La evolved ~13-15 Ma. The middle zone exhumed at ~11 Ma and lower zone close to ~8 Ma indicating erosional unroofing of the MCT sheet. The footwall of MCTZ cooled between 6 and 8 Ma. Analyses of P-T path imply that LHS between MCT and U.MBT zone falls within the kyanite stability field with near isobaric condition. At higher structural level, the temperatures increase gradually with P-T conditions in the sillimanite stability field. The near isothermal (700-800 °C) condition in the GHS, isobaric condition in the MCTZ together with T-t path evidence of GHS that experienced relatively longer duration of near peak temperatures and rapid cooling towards MCTZ, compares the evolution of GHS and inverted metamorphic gradient closely to channel flow predictions.

75 FR 49944 - Notice of Public Meeting, Idaho Falls District Resource Advisory Council Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2010-08-16

... 21-22, 2010 for a two day meeting at the Upper Snake Field Office located at 1405 Hollipark Drive... throughout the Upper Snake Field Office area to discuss policy issues affecting the region such as the... Water Conservation Fund (LWCF) and the critical role it plays in restoring and retaining critical...

Earthquake Forecasting in Northeast India using Energy Blocked Model

NASA Astrophysics Data System (ADS)

Mohapatra, A. K.; Mohanty, D. K.

2009-12-01

In the present study, the cumulative seismic energy released by earthquakes (M ≥ 5) for a period 1897 to 2007 is analyzed for Northeast (NE) India. It is one of the most seismically active regions of the world. The occurrence of three great earthquakes like 1897 Shillong plateau earthquake (Mw= 8.7), 1934 Bihar Nepal earthquake with (Mw= 8.3) and 1950 Upper Assam earthquake (Mw= 8.7) signify the possibility of great earthquakes in future from this region. The regional seismicity map for the study region is prepared by plotting the earthquake data for the period 1897 to 2007 from the source like USGS,ISC catalogs, GCMT database, Indian Meteorological department (IMD). Based on the geology, tectonic and seismicity the study region is classified into three source zones such as Zone 1: Arakan-Yoma zone (AYZ), Zone 2: Himalayan Zone (HZ) and Zone 3: Shillong Plateau zone (SPZ). The Arakan-Yoma Range is characterized by the subduction zone, developed by the junction of the Indian Plate and the Eurasian Plate. It shows a dense clustering of earthquake events and the 1908 eastern boundary earthquake. The Himalayan tectonic zone depicts the subduction zone, and the Assam syntaxis. This zone suffered by the great earthquakes like the 1950 Assam, 1934 Bihar and the 1951 Upper Himalayan earthquakes with Mw > 8. The Shillong Plateau zone was affected by major faults like the Dauki fault and exhibits its own style of the prominent tectonic features. The seismicity and hazard potential of Shillong Plateau is distinct from the Himalayan thrust. Using energy blocked model by Tsuboi, the forecasting of major earthquakes for each source zone is estimated. As per the energy blocked model, the supply of energy for potential earthquakes in an area is remarkably uniform with respect to time and the difference between the supply energy and cumulative energy released for a span of time, is a good indicator of energy blocked and can be utilized for the forecasting of major earthquakes. The proposed process provides a more consistent model of gradual accumulation of strain and non-uniform release through large earthquakes and can be applied in the evaluation of seismic risk. The cumulative seismic energy released by major earthquakes throughout the period from 1897 to 2007 of last 110 years in the all the zones are calculated and plotted. The plot gives characteristics curve for each zone. Each curve is irregular, reflecting occasional high activity. The maximum earthquake energy available at a particular time in a given area is given by S. The difference between the theoretical upper limit given by S and the cumulative energy released up to that time is calculated to find out the maximum magnitude of an earthquake which can occur in future. Energy blocked of the three source regions are 1.35*1017 Joules, 4.25*1017 Joules and 0.12*1017 in Joules respectively for source zone 1, 2 and 3, as a supply for potential earthquakes in due course of time. The predicted maximum magnitude (mmax) obtained for each source zone AYZ, HZ, and SPZ are 8.2, 8.6, and 8.4 respectively by this model. This study is also consistent with the previous predicted results by other workers.

Seismic Evidence of A Widely Distributed West Napa Fault Zone, Hendry Winery, Napa, California

NASA Astrophysics Data System (ADS)

Goldman, M.; Catchings, R.; Chan, J. H.; Criley, C.

2015-12-01

Following the 24 August 2014 Mw 6.0 South Napa earthquake, surface rupture was mapped along the West Napa Fault Zone (WNFZ) for a distance of ~ 14 km and locally within zones up to ~ 2 km wide. Near the northern end of the surface rupture, however, several strands coalesced to form a narrow, ~100-m-wide zone of surface rupture. To determine the location, width, and shallow (upper few hundred meters) geometry of the fault zone, we acquired an active-source seismic survey across the northern surface rupture in February 2015. We acquired both P- and S-wave data, from which we developed reflection images and tomographic images of Vp, Vs, Vp/Vs, and Poisson's ratio of the upper 100 m. We also used small explosive charges within surface ruptures located ~600 m north of our seismic array to record fault-zone guided waves. Our data indicate that at the latitude of the Hendry Winery, the WNFZ is characterized by at least five fault traces that are spaced 60 to 200 m apart. Zones of low-Vs, low-Vp/Vs, and disrupted reflectors highlight the fault traces on the tomography and reflection images. On peak-ground-velocity (PGV) plots, the most pronounced high-amplitude guided-wave seismic energy coincides precisely with the mapped surface ruptures, and the guided waves also show discrete high PGV zones associated with unmapped fault traces east of the surface ruptures. Although the surface ruptures of the WNFZ were observed only over a 100-m-wide zone at the Hendry Winery, our data indicate that the fault zone is at least 400 m wide, which is probably a minimum width given the 400-m length of our seismic profile. Slip on the WNFZ is generally considered to be low relative to most other Bay Area faults, but we suggest that the West Napa Fault is a zone of widely distributed shear, and to fully account for the total slip on the WNFZ, slip on all traces of this wide fault zone must be considered.

Geologic framework and hydrogeologic characteristics of the Glen Rose limestone, Camp Stanley Storage Activity, Bexar County, Texas

USGS Publications Warehouse

Clark, Allan K.

2004-01-01

The Trinity aquifer is a regional water source in the Hill Country of south-central Texas that supplies water for agriculture, commercial, domestic, and stock purposes. Rocks of the Glen Rose Limestone, which compose the upper zone and upper part of the middle zone of the Trinity aquifer, crop out at the Camp Stanley Storage Activity (CSSA), a U.S. Army weapons and munitions supply, maintenance, and storage facility in northern Bexar County (San Antonio area) (fig. 1). On its northeastern, eastern, and southern boundaries, the CSSA abuts the Camp Bullis Training Site, a U.S. Army field training site for military and Federal government agencies. During 2003, the U.S. Geological Survey (USGS), in cooperation with the U.S. Army, studied the outcropping Glen Rose Limestone at the CSSA and immediately adjacent area (Camp Stanley study area, fig. 1) to identify and map the hydrogeologic subdivisions and faults of the Glen Rose Limestone at the facility. The results of the study are intended to help resource managers improve their understanding of the distribution of porosity and permeability of the outcropping rocks, and thus the conditions for recharge and the potential for contaminants to enter the Glen Rose Limestone. This study followed a similar study done by the USGS at Camp Bullis (Clark, 2003). The purpose of this report is to present the geologic framework and hydrogeologic characteristics of the Glen Rose Limestone in the study area. The hydrogeologic nomenclature follows that introduced by Clark (2003) for the outcropping Glen Rose Limestone at Camp Bullis in which the upper member of the Glen Rose Limestone (hereinafter, upper Glen Rose Limestone), which is coincident with the upper zone of the Trinity aquifer, is divided into five intervals on the basis of observed lithologic and hydrogeologic properties. An outcrop map, two generalized sections, related illustrations, and a table summarize the description of the framework and distribution of characteristics.

Imaging of Upper-Mantle Upwelling Beneath the Salton Trough, Southern California, by Joint Inversion of Ambient Noise Dispersion Curves and Receiver Functions

NASA Astrophysics Data System (ADS)

Klemperer, S. L.; Barak, S.

2016-12-01

We present a new 2D shear-wave velocity model of the crust and upper-mantle across the Salton Trough, southern California, obtained by jointly inverting our new dataset of receiver functions and our previously published Rayleigh-wave group-velocity model (Barak et al., G-cubed, 2015), obtained from ambient-noise tomography. Our results show an upper-mantle low-velocity zone (LVZ) with Vs ≤4.2 km/s extending from the Elsinore Fault to the Sand Hills Fault, that together bracket the full width of major San Andreas dextral motion since its inception 6 Ma b.p., and underlying the full width of low topography of the Imperial Valley and Salton Trough. The lateral extent of the LVZ is coincident with the lateral extent of an upper-mantle anisotropic region interpreted as a zone of SAF-parallel melt pockets (Barak & Klemperer, Geology, 2016). The shallowest part of the LVZ is 40 km depth, coincident with S-receiver function images. The western part of the LVZ, between the Elsinore and San Jacinto faults (the region of greatest modern dextral slip), appears to continue to significantly greater depth; but a puzzling feature of our preliminary models is that the eastern part of the LVZ, from the San Jacinto Fault to the Sand Hills Fault, appears to be underlain by more-normalvelocity upper mantle (Vs ≥ 4.5 km/s) below 75 km depth. We compare our model to the current SCEC community models CVM-H and CVM-S, and to P-wave velocity models obtained by the active-source Salton Sea Imaging Project (SSIP). The hypothesized lower-crustal low-velocity zone beneath the Salton Trough in our previous model (Barak et al., G-cubed, 2015), there interpreted as a region of partial melt, is not supported by our new modeling. Melt may be largely absent from the lower crust of the Salton trough; but appears required in the upper mantle at depths as shallow as 40 km.

Student Teachers in the Contact Zone: Developing Critical Intercultural "Teacherhood" in Kindergarten Teacher Education

ERIC Educational Resources Information Center

Layne, Heidi; Lipponen, Lasse

2016-01-01

This paper reports on the results of a narrative-grounded investigation of student teachers' intercultural experiences and learning during their teaching practice. Our interest is in the meaning of the intercultural contact zone and how education for diversities is conceptualised and reflected upon in Finnish teacher education. Critical event…

The Hellenic Subduction Zone: A tomographic image and its geodynamic implications

NASA Astrophysics Data System (ADS)

Spakman, W.; Wortel, M. J. R.; Vlaar, N. J.

1988-01-01

New tomographic images of the Hellenic subduction zone demonstrate slab penetration in the Aegean Upper Mantle to depths of at least 600 km. Beneath Greece the lower part of the slab appears to be detached at a depth of about 200 km whereas it still seems to be unruptured beneath the southern Aegean. Schematically we derive minimum time estimates for the duration of the Hellenic subduction zone that range from 26 to 40 Ma. This is considerably longer than earlier estimates which vary between 5 and about 13 Ma.

Method for producing viscous hydrocarbons

DOEpatents

Poston, Robert S.

1982-01-01

A method for recovering viscous hydrocarbons and synthetic fuels from a subterranean formation by drilling a well bore through the formation and completing the well by cementing a casing means in the upper part of the pay zone. The well is completed as an open hole completion and a superheated thermal vapor stream comprised of steam and combustion gases is injected into the lower part of the pay zone. The combustion gases migrate to the top of the pay zone and form a gas cap which provides formation pressure to produce the viscous hydrocarbons and synthetic fuels.

How Deep is the Critical Zone: A Scientific Question with Potential Impact For Decision-makers in Areas of Shale-Gas Development and Hydraulic Fracturing

NASA Astrophysics Data System (ADS)

Brantley, S. L.

2014-12-01

Citizens living in areas of shale-gas development such as the Marcellus gas play in Pennsylvania and surrounding states are cognizant of the possibility that drilling and production of natural gas -- including hydraulic fracturing -- may have environmental impacts on their water. The Critical Zone is defined as the zone from vegetation canopy to the lower limits of groundwater. This definition is nebulous in terms of the lower limit, and yet, defining the bottom of the Critical Zone is important if citizens are to embrace shale-gas development. This is because, although no peer-reviewed study has been presented that documents a case where hydraulic fracturing or formation fluids have migrated upwards from fracturing depths to drinking water resources, a few cases of such leakage have been alleged. On the other hand, many cases of methane migration into aquifers have been documented to occur and some have been attributed to shale-gas development. The Critical Zone science community has a role to play in understanding such contamination problems, how they unfold, and how they should be ameliorated. For example, one big effort of the Critical Zone science community is to promote sharing of data describing the environment. This data effort has been extended to provide data for citizens to understand water quality by a team known as the Shale Network. As scientists learn to publish data online, these efforts must also be made accessible to non-scientists. As citizens access the data, the demand for data will grow and all branches of government will eventually respond by providing more accessible data that will help the public and policy-makers make decisions.

Origin and emplacement of the andesite of Burroughs Mountain, a zoned, large-volume lava flow at Mount Rainier, Washington, USA

USGS Publications Warehouse

Stockstill, K.R.; Vogel, T.A.; Sisson, T.W.

2002-01-01

Burroughs Mountain, situated at the northeast foot of Mount Rainier, WA, exposes a large-volume (3.4 km3) andesitic lava flow, up to 350 m thick and extending 11 km in length. Two sampling traverses from flow base to eroded top, over vertical sections of 245 and 300 m, show that the flow consists of a felsic lower unit (100 m thick) overlain sharply by a more mafic upper unit. The mafic upper unit is chemically zoned, becoming slightly more evolved upward; the lower unit is heterogeneous and unzoned. The lower unit is also more phenocryst-rich and locally contains inclusions of quenched basaltic andesite magma that are absent from the upper unit. Widespread, vuggy, gabbronorite-to-diorite inclusions may be fragments of shallow cumulates, exhumed from the Mount Rainier magmatic system. Chemically heterogeneous block-and-ash-flow deposits that conformably underlie the lava flow were the earliest products of the eruptive episode. The felsic-mafic-felsic progression in lava composition resulted from partial evacuation of a vertically-zoned magma reservoir, in which either (1) average depth of withdrawal increased, then decreased, during eruption, perhaps due to variations in effusion rate, or (2) magmatic recharge stimulated ascent of a plume that brought less evolved magma to shallow levels at an intermediate stage of the eruption. Pre-eruptive zonation resulted from combined crystallization- differentiation and intrusion(s) of less evolved magma into the partly crystallized resident magma body. The zoned lava flow at Burroughs Mountain shows that, at times, Mount Rainier's magmatic system has developed relatively large, shallow reservoirs that, despite complex recharge events, were capable of developing a felsic-upward compositional zonation similar to that inferred from large ash-flow sheets and other zoned lava flows. ?? 2002 Elsevier Science B.V. All rights reserved.

The Electrical Resistivity Structure of the Eastern Anatolian Collision Zone, Northeastern Anatolia

NASA Astrophysics Data System (ADS)

Cengiz, Özlem; Tuǧrul Başokur, Ahmet; Tolak Çiftçi, Elif

2016-04-01

The Northeastern Anatolia is located at the intensely deformed Eastern Anatolian Collision Zone (EACZ), and its tectonic framework is characterized by the collision of the Arabian plate with Eurasian. Although extensive attention is given to understand the crustal and upper mantle processes at this convergent boundary, there is still an ongoing debate over the geodynamic processes of the region. In this study, we were specifically interested in the geoelectric properties and thus geodynamics of the crust beneath the EACZ. Magnetotelluric (MT) measurements were made on two profiles across the north of the EACZ in 1998 as part of a national project undertaken by the Turkish Petroleum Corporation (TPAO). MT data in the frequency range of 300-0.001 Hz were collected from 168 stations located along 78 km north to south and 47 km west to east profiles where direct convergence occurs between Arabian and Eurasian plates. Two and three-dimensional inversion algorithms were used to obtain resistivity models of the study area. According to these models, the upper crust consists of low resistivity sedimentary rocks (<30 Ωm) that are underlain by highly resistive (~500-1000 Ωm) crystalline basement rocks of the Eastern Anatolian Accretionary Complex and Pontides. While the upper and lower crustal resistivity at the northern part of the study area shows a layered structure, significant horizontal and vertical variations for the rest of the EACZ exists on resistivity models. The broad low resistivity zones (<50 Ωm) observed at mid and lower crustal levels throughout the EACZ. These fluid-rich regions along with high temperatures could indicate weak zones representing the locations of active deformation induced by continent-continent collision and correlate with volcanic centers in the region. The variation in the resistivity structure supports the southward subduction model with the resistive continental block and the deep conductive zones presumably corresponding to the oceanic crust.

Imaging the North Anatolian Fault using the scattered teleseismic wavefield

NASA Astrophysics Data System (ADS)

Thompson, D. A.; Rost, S.; Houseman, G. A.; Cornwell, D. G.; Turkelli, N.; Teoman, U.; Kahraman, M.; Altuncu Poyraz, S.; Gülen, L.; Utkucu, M.; Frederiksen, A. W.; Rondenay, S.

2013-12-01

The North Anatolian Fault Zone (NAFZ) is a major continental strike-slip fault system, similar in size and scale to the San Andreas system, that extends ˜1200 km across Turkey. In 2012, a new multidisciplinary project (FaultLab) was instigated to better understand deformation throughout the entire crust in the NAFZ, in particular the expected transition from narrow zones of brittle deformation in the upper crust to possibly broader shear zones in the lower crust/upper mantle and how these features contribute to the earthquake loading cycle. This contribution will discuss the first results from the seismic component of the project, a 73 station network encompassing the northern and southern branches of the NAFZ in the Sakarya region. The Dense Array for North Anatolia (DANA) is arranged as a 6×11 grid with a nominal station spacing of 7 km, with a further 7 stations located outside of the main grid. With the excellent resolution afforded by the DANA network, we will present images of crustal structure using the technique of teleseismic scattering tomography. The method uses a full waveform inversion of the teleseismic scattered wavefield coupled with array processing techniques to infer the properties and location of small-scale heterogeneities (with scales on the order of the seismic wavelength) within the crust. We will also present preliminary results of teleseismic scattering migration, another powerful method that benefits from the dense data coverage of the deployed seismic network. Images obtained using these methods together with other conventional imaging techniques will provide evidence for how the deformation is distributed within the fault zone at depth, providing constraints that can be used in conjunction with structural analyses of exhumed fault segments and models of geodetic strain-rate across the fault system. By linking together results from the complementary techniques being employed in the FaultLab project, we aim to produce a comprehensive picture of fault structure and dynamics throughout the crust and shallow upper mantle of this major active fault zone.

Dynamic topography in subduction zones: insights from laboratory models

NASA Astrophysics Data System (ADS)

Bajolet, Flora; Faccenna, Claudio; Funiciello, Francesca

2014-05-01

The topography in subduction zones can exhibit very complex patterns due to the variety of forces operating this setting. If we can deduce the theoretical isostatic value from density structure of the lithosphere, the effect of flexural bending and the dynamic component of topography are difficult to quantify. In this work, we attempt to measure and analyze the topography of the overriding plate during subduction compared to a pure shortening setting. We use analog models where the lithospheres are modeled by thin-sheet layers of silicone putty lying on low-viscosity syrup (asthenosphere). The model is shorten by a piston pushing an oceanic plate while a continental plate including a weak zone to localize the deformation is fixed. In one type of experiments, the oceanic plate bends and subducts underneath the continental one; in a second type the two plates are in contact without any trench, and thus simply shorten. The topography evolution is monitored with a laser-scanner. In the shortening model, the elevation increases progressively, especially in the weak zone, and is consistent with expected isostatic values. In the subduction model, the topography is characterized, from the piston to the back-wall, by a low elevation of the dense oceanic plate, a flexural bulge, the trench forming a deep depression, the highly elevated weak zone, and the continental upper plate of intermediate elevation. The topography of the upper plate is consistent with isostatic values for very early stages, but exhibits lower elevations than expected for later stages. For a same amount of shortening of the continental plate, the thickening is the same and the plate should have the same elevation in both types of models. However, comparing the topography at 20, 29 and 39% of shortening, we found that the weak zone is 0.4 to 0.6 mm lower when there is an active subduction. Theses values correspond to 2.6 to 4 km in nature. Although theses values are high, there are of the same order as dynamic topography and could represent the dynamic effect of the slab sinking into the asthenosphere and lowering the elevation of the upper plate.

Quadrupole mass filter: design and performance for operation in stability zone 3.

PubMed

Syed, Sarfaraz U A H; Hogan, Thomas J; Antony Joseph, Mariya J; Maher, Simon; Taylor, Stephen

2013-10-01

The predicted performance of a quadrupole mass filter (QMF) operating in Mathieu stability zone 3 is described in detail using computer simulations. The investigation considers the factors that limit the ultimate maximum resolution (Rmax) and percentage transmission (%Tx), which can be obtained for a given QMF for a particular scan line of operation. The performance curve (i.e., the resolution (R) versus number (N) of radio frequency (rf) cycles experienced by the ions in the mass filter) has been modeled for the upper and lower tip of stability zone 3. The saturation behavior of the performance curve observed in practice for zone 3 is explained. Furthermore, new design equations are presented by examining the intersection of the scan line with stability zone 3. Resolution versus transmission characteristics of stability zones 1 and 3 are compared and the dependence of performance for zones 1 and 3 is related to particular instrument operating parameters.

Hydrologic Synthesis Across the Critical Zone Observatory Network: A Step Towards Understanding the Coevolution of Critical Zone Function and Structure

NASA Astrophysics Data System (ADS)

Wlostowski, A. N.; Harman, C. J.; Molotch, N. P.

2017-12-01

The physical and biological architecture of the Earth's Critical Zone controls hydrologic partitioning, storage, and chemical evolution of precipitated water. The Critical Zone Observatory (CZO) Network provides an ideal platform to explore linkages between catchment structure and hydrologic function across a gradient of geologic and climatic settings. A legacy of hypothesis-motivated research at each site has generated a wealth of data characterizing the architecture and hydrologic function of the critical zone. We will present a synthesis of this data that aims to elucidate and explain (in the sense of making mutually intelligible) variations in hydrologic function across the CZO network. Top-down quantitative signatures of the storage and partitioning of water at catchment scales extracted from precipitation, streamflow, and meteorological data will be compared with each other, and provide quantitative benchmarks to assess differences in perceptual models of hydrologic function at each CZO site. Annual water balance analyses show that CZO sites span a wide gradient of aridity and evaporative partitioning. The aridity index (PET/P) ranges from 0.3 at Luquillo to 4.3 at Reynolds Creek, while the evaporative index (E/P) ranges from 0.3 at Luquillo (Rio Mamayes) to 0.9 at Reynolds Creek (Reynolds Creek Outlet). Snow depth and SWE observations reveal that snowpack is an important seasonal storage reservoir at three sites: Boulder, Jemez, Reynolds Creek and Southern Sierra. Simple dynamical models are also used to infer seasonal patterns of subsurface catchment storage. A root-zone water balance model reveals unique seasonal variations in plant-available water storage. Seasonal patterns of plant-available storage are driven by the asynchronicity of seasonal precipitation and evaporation cycles. Catchment sensitivity functions are derived at each site to infer relative changes in hydraulic storage (the apparent storage reservoir responsible for modulating streamflow generation). Storage-discharge relationships vary widely across the Network, and may be associated with inter-site differences in sub-surface architecture. Moving forward, we seek to reconcile top-down analysis results against the bottom-up understanding of critical zone structure and hydrologic function at each CZO site.

Double diffusion in the frontal zones of the Yellow and East China Seas in winter

NASA Astrophysics Data System (ADS)

Oh, K.; Lee, S.

2017-12-01

Where the cold, fresh water of the Yellow Sea (YS) and the warm, salty water of the East China Sea (ECS) meet, northern and southern fronts are formed in the southeastern YS and the northwestern ECS, respectively. Strong thermohaline fronts are formed on the northern front, and a strong thermocline and a temperature reversal phenomenon are represented in this front. To understand the water structure of this thermohaline zone, we examined double diffusion in the frontal zones in February 2003 using hydrographic data. In the northern front, the warm, salty Cheju Warm Current Water (CWCW) moved northwards along the bottom layer and the cold, fresh Yellow Sea Cold Water (YSCW) flowed southward in the upper layer. As a result, strong thermohaline fronts forms in the area where the two water masses met, and the slope was developed downward across the front. In this area, a strong thermocline and temperature reversal structures were present. The cold, fresh Korean Coastal Water (KCW) was also found in the upper layer near the thermocline, and has a low-temperature, low-salinity more than surrounding water. When cold, fresh water is located over warm, salty water, heat diffuses through the interface between the two water masses, and then the diffusive-convection can be expected to occur. On the other hand, when warm, salty water overlays cold, fresh water, heat in the upper layer is preferentially transferred downward, and the salt-fingering occurs. The diffusive-convection occurs predominantly in the northern thermohaline front, where the cold, fresh YSCW is situated above the warm, salty CWCW and has the effect of strengthening stratification, so that the water column maintains a physically stable structure. In addition, this phenomenon seems to play a role in maintaining the reversal structure. The salt-fingering occurs in upper layers of the northern front where the cold, fresh YSCW is located over the most cold, fresh KCW. Near the northern thermo-halocline zone, the salt-fingering occurs simultaneously with the diffusive-convection, because three water masses, YSCW, KCW and CWCW, interact in that area. Therefore, it can be seen that the water structure of the northern frontal zone in winter is influenced mainly by the cold, fresh YSCW, the most cold, fresh KCW, and the warm, salty CWCW.

Entrainment and high-density three-dimensional mapping in right atrial macroreentry provide critical complementary information: Entrainment may unmask "visual reentry" as passive.

PubMed

Pathik, Bhupesh; Lee, Geoffrey; Nalliah, Chrishan; Joseph, Stephen; Morton, Joseph B; Sparks, Paul B; Sanders, Prashanthan; Kistler, Peter M; Kalman, Jonathan M

2017-10-01

With the recent advent of high-density (HD) 3-dimensional (3D) mapping, the utility of entrainment is uncertain. However, the limitations of visual representation and interpretation of these high-resolution 3D maps are unclear. The purpose of this study was to determine the strengths and limitations of both HD 3D mapping and entrainment mapping during mapping of right atrial macroreentry. Fifteen patients were studied. The number and type of circuits accounting for ≥90% of the tachycardia cycle length using HD 3D mapping were verified using systematic entrainment mapping. Entrainment sites with an unexpectedly long postpacing interval despite proximity to the active circuit were evaluated. Based on HD 3D mapping, 27 circuits were observed: 12 peritricuspid, 2 upper loop reentry, 10 lower loop reentry, and 3 lateral wall circuits. With entrainment, 17 of the 27 circuits were active: all 12 peritricuspid and 2 upper loop reentry. However, lower loop reentry was confirmed in only 3 of 10, and none of the 3 lateral wall circuits were present. Mean percentage of tachycardia cycle length covered by active circuits was 98% ± 1% vs 97% ± 2% for passive circuits (P = .09). None of the 345 entrainment runs terminated tachycardia or changed tachycardia mechanism. In 8 of 15 patients, 13 examples of unexpectedly long postpacing interval were observed at entrainment sites located distal to localized zones of slow conduction seen on HD 3D mapping. Using HD 3D mapping, "visual reentry" may be due to passive circuitous propagation rather than a critical reentrant circuit. HD 3D mapping provides new insights into regional conduction and helps explain unusual entrainment phenomena. Copyright © 2017 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Facing a changing world: Thermal physiology of American pikas (Ochotona princeps)

USGS Publications Warehouse

Otto, Hans W; Wilson, James A; Beever, Erik

2015-01-01

American pikas (Ochotona princeps) are of concern with respect to warming montane temperatures; however, little information exists regarding their physiological ability to adapt to warming temperatures. Previous studies have shown that pikas have high metabolism and low thermal conductance, which allow survival during cold winters. It has been hypothesized that these characteristics may be detrimental, given the recent warming trends observed in montane ecosystems. We examined resting metabolic rate, surface activity, and den and ambient temperatures (Ta) of pikas in late summer (August 2011 and 2012) at 2 locations in the Rocky Mountains. Resting metabolic rate was calculated to be 2.02 mL O2 · g-1h-1, with a lower critical temperature (LCT) of 28.1 ± 0.2 °C. No upper critical temperature (UCT) could be determined from our data; therefore, the estimated thermoneutral zone (TNZ) was 28.1 °C to at least 35.0 °C (upper experimental temperature). Pikas in this study showed the same bimodal above-talus activity patterns reported in previous studies. Den temperatures in Colorado were correlated with, but consistently lower than, current ambient temperatures. Wyoming den temperatures showed a weak correlation with Ta 20 min prior to the current den temperature. This study is one of few to present data on the physiological response pikas may have to current warming conditions, and the first to perform metabolic measurements in situ. Our data support conclusions of previous studies, specifically MacArthur and Wang (1973, 1974) and Smith (1974), which indicated American pikas may not have the physiological ability to cope with high Ta. Our results also highlight the importance of shaded regions below the talus rocks for behavioral thermoregulation by pikas.

Investigating point zero: The artificial catchment 'Chicken Creek' as an observatory to study critical zone structures and processes of the critical zone in an initial ecosystem

NASA Astrophysics Data System (ADS)

Hüttl, Reinhard F.; Gerwin, Werner

2010-05-01

Recently, earth surface structures reaching from vegetation to the groundwater in the near underground have been termed "critical zone". This zone is "critical" to supporting life on Earth and, thus, the understanding of processes within this zone is of great importance in environmental sciences. Investigating the critical zone requires interdisciplinary and integrative research approaches across the fields of geomorphology, ecology, biology, soil science, hydrology and environmental modeling. A central motivation of the critical zone concept is the need for moving beyond traditional disciplinary boundaries to a more holistic and integrated study of the Earth surface system. However, the critical zone is characterized by complex interactions between abiotic and biotic structures and processes which need to be analyzed for improving our understanding of ecosystem functioning as well as of ecosystem development. To gain a better understanding of these fundamental questions it might be helpful to look at initial ecosystems, i.e. at ecosystems in the initial phase of development. It can be hypothesized that the complexity of a very young ecosystem is lower compared to mature systems and, therefore, structure-process interactions might become more obvious at early than at later stages of development. In this context, an artificial watershed was constructed with well known boundary conditions to investigate the initial ecosystem phase. The catchment ‘Chicken Creek' in Lusatia (Germany; 150 km SE from Berlin) has an area of 6 ha. It was set up with a layer of post-glacial sandy sediments overlying an aquiclude made of clay at the base. These hydrological starting conditions allowed for the formation of a groundwater body within the sandy layer of the experimental catchment. Further, after completion of the construction works in September 2005 the site was left to natural succession and no measures like planting or fertilization were carried out. As the initial phase of ecosystem development is highly dynamic under the prevailing climate conditions and ecosystem structures are formed and altered very rapidly the careful observation of the ongoing processes is essential. Thus, a comprehensive ecological monitoring programme has been started immediately after completion of the watershed to investigate the development and differentiation of structures and processes and their interactions. This paper highlights the conceptual approach of the project and particularly of the artificial watershed. Findings of this comprehensive project over a period of 4 years will be presented.

The constructed catchment Chicken Creek as Critical Zone Observatory under transition

NASA Astrophysics Data System (ADS)

Gerwin, Werner; Schaaf, Wolfgang; Elmer, Michael; Hinz, Christoph

2014-05-01

The constructed catchment Chicken Creek was established in 2005 as an experimental landscape laboratory for ecosystem research. The 6 ha area with clearly defined horizontal as well as vertical boundary conditions was left for an unrestricted primary succession. All Critical Zone elements are represented at this site, which allows the study of most processes occurring at the interface of bio-, pedo-, geo- and hydrosphere. It provides outstanding opportunities for investigating interactions and feedbacks between different evolving compartments during ecosystem development. The catchment is extensively instrumented since 2005 in order to detect transition stages of the ecosystem. Data recorded with a high spatial and temporal resolution include hydrological, geomorphological, pedological, limnological as well as biological parameters. In contrast to other Critical Zone Observatories, this site offers the unique situation of an early stage ecosystem with highly dynamic system properties. The first years of development were characterized by a fast formation of geomorphological structures due to massive erosion processes at the initially non-vegetated surface. Hydrological processes led to the establishment of a local groundwater body within 5 years. In the following years the influence of biological structures like vegetation patterns gained an increasing importance. Feedbacks between developing vegetation and e.g. hydrological features became more and more dominant. As a result, different phases of ecosystem development could be distinguished until now. This observatory offers manifold possibilities to identify and disentangle complex interactions between Critical Zone processes in situ under natural conditions. The originally low complexity of the system is growing with time facilitating the identification of influences of newly developing structures on system functions. Thus, it is possible to study effects of small-scale processes on the whole system at the landscape scale. In addition, the highly dynamic initial system properties allow the observation of multifaceted changes of Critical Zone properties and functions within short periods of time. Chicken Creek could complement the existing network of Critical Zone Observatories which are usually established at ecosystems in a mature state.

Saltwater movement in the upper Floridan aquifer beneath Port Royal Sound, South Carolina

USGS Publications Warehouse

Smith, Barry S.

1994-01-01

Freshwater for Hilton Head Island, South Carolina, is supplied by withdrawals from the Upper Floridan aquifer. Freshwater for the nearby city of Savannah, Georgia, and for the industry that has grown adjacent to the city, has also been supplied, in part, by withdrawal from the Upper Floridan aquifer since 1885. The withdrawal of ground water has caused water levels in the Upper Floridan aquifer to decline over a broad area, forming a cone of depression in the potentiometric surface of the aquifer centered near Savannah. In 1984, the cone of depression extended beneath Hilton Head Island as far as Port Royal Sound. Flow in the aquifer, which had previously been toward Port Royal Sound, has been reversed, and, as a result, saltwater in the aquifer beneath Port Royal Sound has begun to move toward Hilton Head Island. The Saturated-Unsaturated Transport (SUTRA) model of the U.S. Geological Survey was used for the simulation of density-dependent ground-water flow and solute transport for a vertical section of the Upper Floridan aquifer and upper confining unit beneath Hilton Head Island and Port Royal Sound. The model simulated a dynamic equilibrium between the flow of seawater and freshwater in the aquifer near the Gyben-Herzberg position estimated for the period before withdrawals began in 1885; it simulated reasonable movements of brackish water and saltwater from that position to the position determined by chemical analyses of samples withdrawn from the aquifer in 1984, and it approximated hydraulic heads measured in the aquifer in 1976 and 1984. The solute-transport simulations indicate that the transition zone would continue to move toward Hilton Head Island even if pumping ceased on the island. Increases in existing withdrawals or additional withdrawals on or near Hilton Head Island would accelerate movement of the transition zone toward the island, but reduction in withdrawals or the injection of freshwater would slow movement toward the island, according to the simulations. Future movements of the transition zone toward Hilton Head Island will depend on hydraulic gradients in the aquifer beneath the island and the sound. Hydraulic gradients in the Upper Floridan aquifer beneath Hilton Head Island and Port Royal Sound are strongly influenced by withdrawals on the island and near Savannah. Since 1984, withdrawals on Hilton Head Island have increased.

Composite biostratigraphy and microfacies analysis of the Upper Jurassic - Lower Cretaceous carbonate platform to slope successions in Sivrihisar (Eskişehir) region (NW Turkey, Pontides): Remarks on the palaeogeographic evolution of the Western Sakarya Zo

NASA Astrophysics Data System (ADS)

Atasoy, Serdar G.; Altıner, Demir; Okay, Aral I.

2017-04-01

Two stratigraphical sections were measured along the Upper Jurassic - Lower Cretaceous carbonate successions exposed in a tectonic klippe of the Sakarya Zone (Pontides), north of Sivrihisar. According to the biozonation and microfacies types, two coeval but dissimiliar rock successions, separated by a thrust fault, have been detected. These successions belong to different depositional belts of the Edremit-Bursa-Bilecik Carbonate Platform (EBBCP), western Sakarya Zone. The lower succession displays a slope to basin facies and consists of the Kimmeridgian - Berriasian Yosunlukbayırı Formation and the overlying Valanginian Soǧukçam Limestone. Within these deposits the following biozones were defined: Globuligerina oxfordiana - Mohlerina basiliensis Zone (Kimmeridgian), Saccocoma Zone (Lower Tithonian), Protopeneroplis ultragranulata Zone (Upper Tithonian), Crassicollaria (massutiana subzone) Zone (uppermost Tithonian), Calpionella (alpina, Remaniella, elliptica subzones) Zone (Lower Berriasian), Calpionellopsis (simplex, oblonga subzones) Zone (Upper Berriasian) and Calpionellites (darderi subzone) Zone (Lower Valanginian). This succession is overthrusted from north to south by another distinct succession characterized by the shallow marine carbonate facies of the Kimmeridgian Günören Formation. Within this unit Labyrinthina mirabilis - Protopeneroplis striata (Kimmeridgian) Zone is recognized. A facies model is proposed for the Sivrihisar transect of the EBBCP for Kimmeridgian - Valanginian interval, based on the distribution of microfacies types. The toe-of-slope facies are characterized by peloidal-bioclastic packstone, mudstone-wackestone and calpionellid/ radiolarian wackestone-packstone comprising pelagic taxa (calpionellids, radiolaria, Globochaete sp., Pithonella sp., Saccocoma sp., calcareous dinocysts, aptychi, very rare planktonic foraminifera and nannoconids) and rare fossil groups transported from the carbonate platform (benthic foraminifera, microencrusters, worm tubes, bivalve, crinoid and echinoid fragments). These deposits represent the background pelagic deposition on the slope. The slope facies are mainly composed of bioclastic-peloidal/ bioclastic-intraclastic packstone, rudstone-grainstone, bioclastic-lithoclastic floatstone-rudstone and reflect generally the increase in the amount of platform derived material (benthic foraminifera, microencrusters, worm tubes, corals, sponges, bryozoa). The matrix of these coarse grained deposits also contains pelagic taxa (calpionellids, radiolaria, Saccocoma sp., Globochaete sp., Pithonella sp., aptyhci). The slope facies are sometimes intercalataed with the toe-of-slope type facies indicating quiescence periods. The shallow marine carbonate platform deposits are characterized by peloidal-intraclastic poorly washed grainstone with bioclasts, bioclastic mudstone-wackestone, intraclastic packstone-rudstone and contain several shallow marine fossils (benthic foraminifera, encrustres and rare echnoid, bivalve and coral fragments) without any pelagic taxa. These carbonates are interpreted as back-reef platform deposits that should not be far away from the platform margin due to the co-occurence of Protopeneroplis striata and Mohlerina basiliensis, abundant in the shelf edge and reefal areas with the complex benthic foraminifera, Labyrinthina mirabilis common in lagoonal areas. If the position of the studied sections with respect to the EBBCP is considered, the studied basin and slope facies should represent the southern platform margin and slope environments of this carbonate platform that faced an ocean to the south during the Jurassic-Cretaceous. The slope and basinal facies overthrusted by the shallow marine deposits in a region situated to the south of the main İzmir-Ankara-Erzincan (İAE) suture suggests an important disruption and shortening of the EBBCP margin and slope deposits related to the closure of the İAE ocean.

Understanding Differences in the Nitrogen Cycle in Low-Oxygen Zones in the Eastern Tropical North Pacific

NASA Astrophysics Data System (ADS)

Wood, C.; Travis, N. M.; Forbes, M. S.; Casciotti, K. L.

2016-12-01

Hypoxic and anoxic zones are found in oceans worldwide. These zones can be caused by warm water "caps" that trap colder water underneath the warm water so the cold water cannot replenish its oxygen. Processes such as global warming and eutrophication can also contribute to such oxygen-depleted zones. Thus, it is important to study these zones to investigate and reveal the impact humans have on ecosystems worldwide so we can fix the problems we have caused. The Eastern Tropical North Pacific (ETNP), off the southwestern coast of Mexico, contains a natural-oxygen deficient zone. On a research cruise to the ETNP in April 2016, incubations were conducted to measure the rates of nitrification in the upper water column (upper 100 m) at three stations. Incubations were conducted in light and dark bottles spiked with 15N-containing nitrite. In this study, nitrite concentration in incubation starting points was analyzed. For each point, four depths of increasing depth (they varied depending on the station) were analyzed, and for each depth there were three samples. For each sample five absorbance measurements were averaged to calculate nitrite concentration against known standards. Concentrations of nitrite were found to increase moving into the oxygen deficient zone. The nitrite peaks at the coastal stations were at shallower depths than the peak at the centermost station in the low-oxygen zone. At the centermost station within the oxygen-deficient region, the nitrite concentration at the primary peak was 1.6µM, which was the highest point out of all the stations. This nitrite concentration data will be expanded to all stations where 15N addition incubation experiments were performed. In the future, these time-zero data will be combined with time-24 data to calculate nitrite oxidation rates based on 15N isotope analysis. Measuring nitrite oxidation rates will help us further understand processes structuring nitrite accumulation in the ETNP low-oxygen zone.

Crustal strength anisotropy influences landscape form and longevity

NASA Astrophysics Data System (ADS)

Roy, S. G.; Koons, P. O.; Upton, P.; Tucker, G. E.

2013-12-01

Lithospheric deformation is increasingly recognized as integral to landscape evolution. Here we employ a coupled orogenic and landscape model to test the hypothesis that strain-induced crustal failure exerts the dominant control on rates and patterns of orogenic landscape evolution. We assume that erodibility is inversely proportional to cohesion for bedrock rivers host to bedload abrasion. Crustal failure can potentially reduce cohesion by several orders of magnitude along meter scale planar fault zones. The strain-induced cohesion field is generated by use of a strain softening upper crustal rheology in our orogenic model. Based on the results of our coupled model, we predict that topographic anisotropy found in natural orogens is largely a consequence of strain-induced anisotropy in the near surface strength field. The lifespan and geometry of mountain ranges are strongly sensitive to 1) the acute division in erodibility values between the damaged fault zones and the surrounding intact rock and 2) the fault zone orientations for a given tectonic regime. The large division in erodibility between damaged and intact rock combined with the dependence on fault zone orientation provides a spectrum of rates at which a landscape will respond to tectonic or climatic perturbations. Knickpoint migration is about an order of magnitude faster along the exposed cores of fault zones when compared to rates in intact rock, and migration rate increases with fault dip. The contrast in relative erosion rate confines much of the early stage fluvial erosion and establishes a major drainage network that reflects the orientations of exposed fault zones. Slower erosion into the surrounding intact rock typically creates small tributaries that link orthogonally to the structurally confined channels. The large divide in fluvial erosion rate permits the long term persistence of the tectonic signal in the landscape and partly contributes to orogen longevity. Landscape morphology and channel tortuosity together provide critical information on the orientation and spatial distribution of fault damage and the relevant tectonic regime. Our landscape evolution models express similar mechanisms and produce drainage network patterns analogous to those seen in the Southern Alps of New Zealand and the Himalayan Eastern Syntaxis, both centers of active lithospheric deformation.

Concentration-discharge relationships during an extreme event: Contrasting behavior of solutes and changes to chemical quality of dissolved organic material in the Boulder Creek Watershed during the September 2013 flood: SOLUTE FLUX IN A FLOOD EVENT

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

Rue, Garrett P.; Rock, Nathan D.; Gabor, Rachel S.

During the week of September 10-17, 2013, close to 20 inches of rain fell across Boulder County, Colorado, USA. This rainfall represented a 1000-year event that caused massive hillslope erosion, landslides, and mobilization of sediments. The resultant stream flows corresponded to a 100-year flood. For the Boulder Creek Critical Zone Observatory (BC-CZO), this event provided an opportunity to study the effect of extreme rainfall on solute concentration-discharge relationships and biogeochemical catchment processes. We observed base cation and dissolved organic carbon (DOC) concentrations at two sites on Boulder Creek following the recession of peak flow. We also isolated three distinct fractionsmore » of dissolved organic matter (DOM) for chemical characterization. At the upper site, which represented the forested mountain catchment, the concentrations of the base cations Ca, Mg and Na were greatest at the peak flood and decreased only slightly, in contrast with DOC and K concentrations, which decreased substantially. At the lower site within urban corridor, all solutes decreased abruptly after the first week of flow recession, with base cation concentrations stabilizing while DOC and K continued to decrease. Additionally, we found significant spatiotemporal trends in the chemical quality of organic matter exported during the flood recession, as measured by fluorescence, 13C-NMR spectroscopy, and FTICR-MS. Similar to the effect of extreme rainfall events in driving landslides and mobilizing sediments, our findings suggest that such events mobilize solutes by the flushing of the deeper layers of the critical zone, and that this flushing regulates terrestrial-aquatic biogeochemical linkages during the flow recession.« less

Development of a Probabilistic Decision-Support Model to Forecast Coastal Resilience

NASA Astrophysics Data System (ADS)

Wilson, K.; Safak, I.; Brenner, O.; Lentz, E. E.; Hapke, C. J.

2016-02-01

Site-specific forecasts of coastal change are a valuable management tool in preparing for and assessing storm-driven impacts in coastal areas. More specifically, understanding the likelihood of storm impacts, recovery following events, and the alongshore variability of both is central in evaluating vulnerability and resiliency of barrier islands. We introduce a probabilistic modeling framework that integrates hydrodynamic, anthropogenic, and morphologic components of the barrier system to evaluate coastal change at Fire Island, New York. The model is structured on a Bayesian network (BN), which utilizes observations to learn statistical relationships between system variables. In addition to predictive ability, probabilistic models convey the level of confidence associated with a prediction, an important consideration for coastal managers. Our model predicts the likelihood of morphologic change on the upper beach based on several decades of beach monitoring data. A coupled hydrodynamic BN combines probabilistic and deterministic modeling approaches; by querying nearly two decades of nested-grid wave simulations that account for both distant swells and local seas, we produce scenarios of event and seasonal wave climates. The wave scenarios of total water level - a sum of run up, surge and tide - and anthropogenic modification are the primary drivers of morphologic change in our model structure. Preliminary results show the hydrodynamic BN is able to reproduce time series of total water levels, a critical validation process before generating scenarios, and forecasts of geomorphic change over three month intervals are up to 70% accurate. Predictions of storm-induced change and recovery are linked to evaluate zones of persistent vulnerability or resilience and will help managers target restoration efforts, identify areas most vulnerable to habitat degradation, and highlight resilient zones that may best support relocation of critical infrastructure.

Controls of Parent Material and Topography on Soil Carbon Storage in the Critical Zone

NASA Astrophysics Data System (ADS)

Patton, N. R.; Seyfried, M. S.; Lohse, K. A.; Link, T. E.

2014-12-01

Semi-arid environments make up a large percentage of the world's terrestrial ecosystems, and climate is a major factor influencing soil carbon storage and release. However, the roles of local controls such as parent material, aspect and microtopography have received less attention and are important for consideration in soil carbon modeling. The purpose of this study is to understand the role that parent material, aspect and micro-topography play in storage and release of soil carbon along an elevation gradient in a semi-arid climate. Johnston Draw (JD) is a first order watershed within the Reynolds Creek Critical Zone Observatory in southwestern Idaho with underlining late cretaceous, granitic Idaho batholith bedrock. Upper Sheep Creek (USC) is a first order watershed consisting of basalt. Both watersheds were chosen for this project due to similar size, aspect, elevation, vegetation and for the contrast in parent material. Two transects, totaling approximately nine soil pits, were excavated on both the north and south facing slopes of each watershed running parallel to the water channel. Soil carbon was generally higher in basalt compared to the granite parent material in pits with similar aspect, elevation and vegetation. Preliminary data using soil organic matter (SOM) as a proxy for organic carbon (OC) and soil water dynamics showed that percent OC declines markedly with elevation in JD and soil depth at lower elevations and is more homogenous throughout the profile moving up elevation (1646 meters 4.3-9.7%; 1707 meters 6.87-3.83%). Similarly, aspect controls patterns of SOM at depth more strongly at lower elevations. Findings from our study suggest that parent material and topography may play as important roles in semi-arid ecosystems as climate factors in controlling soil carbon storage.

Work zone safety analysis.

DOT National Transportation Integrated Search

2013-11-01

This report presents research performed analyzing crashes in work zones in the state of New Jersey so as to : identify critical areas in work zones susceptible to crashes and key factors that contribute to these crashes. A field : data collection on ...

Upper Ocean Evolution Across the Beaufort Sea Marginal Ice Zone from Autonomous Gliders

NASA Astrophysics Data System (ADS)

Lee, Craig; Rainville, Luc; Perry, Mary Jane

2016-04-01

The observed reduction of Arctic summertime sea ice extent and expansion of the marginal ice zone (MIZ) have profound impacts on the balance of processes controlling sea ice evolution, including the introduction of several positive feedback mechanisms that may act to accelerate melting. Examples of such feedbacks include increased upper ocean warming though absorption of solar radiation, elevated internal wave energy and mixing that may entrain heat stored in subsurface watermasses (e.g., the relatively warm Pacific Summer (PSW) and Atlantic (AW) waters), and elevated surface wave energy that acts to deform and fracture sea ice. Spatial and temporal variability in ice properties and open water fraction impact these processes. To investigate how upper ocean structure varies with changing ice cover, and how the balance of processes shift as a function of ice fraction and distance from open water, four long-endurance autonomous Seagliders occupied sections that extended from open water, through the marginal ice zone, deep into the pack during summer 2014 in the Beaufort Sea. Sections reveal strong fronts where cold, ice-covered waters meet waters that have been exposed to solar warming, and O(10 km) scale eddies near the ice edge. In the pack, Pacific Summer Water and a deep chlorophyll maximum form distinct layers at roughly 60 m and 80 m, respectively, which become increasingly diffuse as they progress through the MIZ and into open water. The isopynal layer between 1023 and 1024 kgm-3, just above the PSW, consistently thickens near the ice edge, likely due to mixing or energetic vertical exchange associated with strong lateral gradients in this region. This presentation will discuss the upper ocean variability, its relationship to sea ice extent, and evolution over the summer to the start of freeze up.

Upper Ocean Evolution Across the Beaufort Sea Marginal Ice Zone from Autonomous Gliders

NASA Astrophysics Data System (ADS)

Lee, C.; Rainville, L.; Perry, M. J.

2016-02-01

The observed reduction of Arctic summertime sea ice extent and expansion of the marginal ice zone (MIZ) have profound impacts on the balance of processes controlling sea ice evolution, including the introduction of several positive feedback mechanisms that may act to accelerate melting. Examples of such feedbacks include increased upper ocean warming though absorption of solar radiation, elevated internal wave energy and mixing that may entrain heat stored in subsurface watermasses (e.g., the relatively warm Pacific Summer (PSW) and Atlantic (AW) waters), and elevated surface wave energy that acts to deform and fracture sea ice. Spatial and temporal variability in ice properties and open water fraction impact these processes. To investigate how upper ocean structure varies with changing ice cover, and how the balance of processes shift as a function of ice fraction and distance from open water, four long-endurance autonomous Seagliders occupied sections that extended from open water, through the marginal ice zone, deep into the pack during summer 2014 in the Beaufort Sea. Sections reveal strong fronts where cold, ice-covered waters meet waters that have been exposed to solar warming, and O(10 km) scale eddies near the ice edge. In the pack, Pacific Summer Water and a deep chlorophyll maximum form distinct layers at roughly 60 m and 80 m, respectively, which become increasingly diffuse as they progress through the MIZ and into open water. The isopynal layer between 1023 and 1024 kg m-3, just above the PSW, consistently thickens near the ice edge, likely due to mixing or energetic vertical exchange associated with strong lateral gradients in this region. This presentation will discuss the upper ocean variability, its relationship to sea ice extent, and evolution over the summer to the start of freeze up.

Transition from slab to slabless: Results from the 1993 Mendocino triple junction seismic experiment

USGS Publications Warehouse

Beaudoin, B.C.; Godfrey, N.J.; Klemperer, S.L.; Lendl, C.; Trehu, A.M.; Henstock, T.J.; Levander, A.; Holl, J.E.; Meltzer, A.S.; Luetgert, J.H.; Mooney, W.D.

1996-01-01

Three seismic refraction-reflection profiles, part of the Mendocino triple junction seismic experiment, allow us to compare and contrast crust and upper mantle of the North American margin before and after it is modified by passage of the Mendocino triple junction. Upper crustal velocity models reveal an asymmetric Great Valley basin overlying Sierran or ophiolitic rocks at the latitude of Fort Bragg, California, and overlying Sierran or Klamath rocks near Redding, California. In addition, the upper crustal velocity structure indicates that Franciscan rocks underlie the Klamath terrane east of Eureka, California. The Franciscan complex is, on average, laterally homogeneous and is thickest in the triple junction region. North of the triple junction, the Gorda slab can be traced 150 km inboard from the Cascadia subduction zone. South of the triple junction, strong precritical reflections indicate partial melt and/or metamorphic fluids at the base of the crust or in the upper mantle. Breaks in these reflections are correlated with the Maacama and Bartlett Springs faults, suggesting that these faults extend at least to the mantle. We interpret our data to indicate tectonic thickening of the Franciscan complex in response to passage of the Mendocino triple junction and an associated thinning of these rocks south of the triple junction due to assimilation into melt triggered by upwelling asthenosphere. The region of thickened Franciscan complex overlies a zone of increased scattering, intrinsic attenuation, or both, resulting from mechanical mixing of lithologies and/or partial melt beneath the onshore projection of the Mendocino fracture zone. Our data reveal that we have crossed the southern edge of the Gorda slab and that this edge and/or the overlying North American crust may have fragmented because of the change in stress presented by the edge.

Three-Dimensional Distribution of Larval Fish Habitats in the Shallow Oxygen Minimum Zone in the Eastern Tropical Pacific Ocean off Mexico

NASA Astrophysics Data System (ADS)

Davies, S.; Sanchez Velasco, L.; Beier, E.; Godinez, V. M.; Barton, E. D.; Tamayo, A.

2016-02-01

Three-dimensional distribution of larval fish habitats was analyzed, from the upper limit of the shallow oxygen minimum zone ( 0.2 mL/L) to the sea surface, in the eastern tropical Pacific Ocean off Mexico in February 2010.The upper limit rises from 250 m depth in the entrance of the Gulf of California to 80 m depth off Cabo Corrientes. Three larval fish habitats were defined statistically: (i) a Gulf of California habitat dominated by Anchoa spp. larvae (epipelagic species), constrained to the oxygenated surface layer (>3.5 mL/L) in and above the thermocline ( 60 m depth), and separated by a salinity front from the Tropical Pacific habitat; (ii) a Tropical Pacific habitat, dominated by Vinciguerria lucetia larvae (mesopelagic species), located throughout the sampled water column, but with the highest abundance in the oxygenated upper layer above the thermocline; (iii) an Oxygen Minimum habitat defined mostly below the thermocline in hypoxic (<1 mL/L; 70 m depth) and anoxic (<0.2 mL/L; 80 m depth) water off Cabo Corrientes. This subsurface hypoxic habitat had the highest species richness and larval abundance, with dominance of Bregmaceros bathymaster, an endemic neritic pelagic species; which was an unexpected result. This maybe associated with the shoaling of the upper limit of the shallow oxygen minimum zone near the coast, a result of the strong costal upwelling detected by the Bakun Index. In this region of strong and semi-continuous coastal upwelling in the eastern tropical Pacific off Mexico, the shallow hypoxic water does not have dramatic effects on the total larval fish abundance but appears to affect species composition.

Tomography of the upper mantle beneath the African/Iberian collision zone

NASA Astrophysics Data System (ADS)

Mickael, B.; Nolet, G.; Villasenor, A.; Josep, G.; Thomas, C.

2013-12-01

During Cenozoic, geodynamics of the western Mediterranean domain has been characterized by a complex history of subduction of Mesozoic oceanic lithosphere. The final stage of these processes is proposed to have led to the development of the Calabria and Gibraltar arcs, whose formation is still under debate. In this study we take advantage of the dense broadband-station networks now available in Alborán Sea region, to develop a high-resolution 3D tomographic P velocity model of the upper mantle beneath the African/Iberian collision zone that will bring new constraints on the past dynamics of this zone. The model is based on 13200 teleseismic arrival times recorded between 2008 and 2012 at 279 stations for which cross-correlation delays are measured with a new technique in different frequency bands centered between 0.03 and 1.0 Hz, and interpreted using multiple frequency tomography. Our model shows, beneath Alborán Sea, a strong (~ 4%) fast vertically dipping anomaly observed to at least 650 km depth. The arched shape of this anomaly and its extent at depth are coherent with a lithospheric slab, thus favoring the hypothesis of a westward consumption of the Ligurian ocean slab by roll-back during Cenozoic. In addition to this fast anomaly in the deep upper-mantle, several high intensity slow anomalies are widely observed in the lithosphere and asthenosphere beneath Morocco and southern Spain. These anomalies are correlated at surface with the position of the orogens (Rif and Atlas) and with Cenozoic volcanic fields. We thus confirm the presence, beneath Morocco, of an anomalous (hot) upper mantle, with piece of evidence for a lateral connection with the Canary volcanic islands, likely indicating a lateral spreading of the Canary plume to the east.

Effects of Ginger Supplementation on Cell Cycle Biomarkers in the Normal-Appearing Colonic Mucosa of Patients at Increased Risk for Colorectal Cancer: Results from a Pilot, Randomized, Controlled Trial

PubMed Central

Citronberg, Jessica; Bostick, Roberd; Ahearn, Thomas; Turgeon, D. Kim; Ruffin, Mack T.; Djuric, Zora; Sen, Ananda; Brenner, Dean E.; Zick, Suzanna M.

2013-01-01

To estimate the effects of ginger on apoptosis, proliferation, and differentiation in the normal-appearing colonic mucosa, we randomized 20 people at increased risk for colorectal cancer to 2.0 g of ginger or placebo daily for 28 days in a pilot trial. Overall expression and distributions of Bax, Bcl-2, p21, hTERT and MIB-1 (Ki-67) in colorectal crypts in rectal mucosa biopsies were measured using automated immunohistochemistry and quantitative image analysis. Relative to placebo, Bax expression in the ginger group decreased 15.6% (p = 0.78) in the whole crypts, 6.6% (p = 0.95) in the upper 40% (differentiation zone) of crypts, and 21.7% (p = 0.67) in the lower 60% (proliferative zone) of crypts; however, there was a 19% increase (p = 0.14) in Bax expression in the upper 40% relative to the whole crypt. While p21 and Bcl-2 expression remained relatively unchanged, hTERT expression in the whole crypts decreased by 41.2% (p = 0.05); the estimated treatment effect on hTERT expression was larger in the upper 40% of crypts (−47.9%; p = 0.04). In the ginger group, MIB-1 expression decreased in the whole crypts, upper 40% of crypts, and lower 60% of crypts by 16.9% (p = 0.39), 46.8% (p = 0.39), and 15.3% (p = 0.41), respectively. These pilot study results suggest that ginger may reduce proliferation in the normal-appearing colorectal epithelium and increase apoptosis and differentiation relative to proliferation—especially in the differentiation zone of the crypts, and support a larger study to further investigate these results. PMID:23303903

Seismically imaging the Afar plume

NASA Astrophysics Data System (ADS)

Hammond, J. O.; Kendall, J. M.; Bastow, I. D.; Stuart, G. W.; Keir, D.; Ayele, A.; Ogubazghi, G.; Ebinger, C. J.; Belachew, M.

2011-12-01

Plume related flood basalt volcanism in Ethiopia has long been cited to have instigated continental breakup in northeast Africa. However, to date seismic images of the mantle beneath the region have not produced conclusive evidence of a plume-like structure. As a result the nature and even existence of a plume in the region and its role in rift initiation and continental rupture are debated. Previous seismic studies using regional deployments of sensors in East-Africa show that low seismic velocities underlie northeast Africa, but their resolution is limited to the top 200-300km of the Earth. Thus, the connection between the low velocities in the uppermost mantle and those imaged in global studies in the lower mantle is unclear. We have combined new data from Afar, Ethiopia with 6 other regional experiments and global network stations across Ethiopia, Eritrea, Djibouti and Yemen, to produce high-resolution models of upper mantle P- and S- wave velocities to the base of the transition zone. Relative travel time tomographic inversions show that the top 100km is dominated by focussed low velocity zones, likely associated with melt in the lithosphere/uppermost asthenosphere. Below these depths a broad SW-NE oriented sheet like upwelling extends down to the top of the transition zone. Within the transition zone two focussed sharp-sided low velocity regions exist: one beneath the Western Ethiopian plateau outside the rift valley, and the other beneath the Afar depression. The nature of the transition zone anomalies suggests that small upwellings may rise from a broader low velocity plume-like feature in the lower mantle. This interpretation is supported by numerical and analogue experiments that suggest the 660km phase change and viscosity jump may impede flow from the lower to upper mantle creating a thermal boundary layer at the base of the transition zone. This allows smaller, secondary upwellings to initiate and rise to the surface. Our images of secondary upwellings suggest that there is no evidence for a plume in the classical sense (i.e. a narrow conduit). Instead, we propose that secondary upwellings rise from the base of the transition zone and connect in the upper mantle. This coupled with measurements of seismic anisotropy suggest that mantle material flows northeast towards Arabia, and may be responsible for the dramatic dynamic topography observed in northeast Africa and western Arabia.

Coccolithophore ecology at the HOT station ALOHA, Hawaii

NASA Astrophysics Data System (ADS)

Cortés, Mara Y.; Bollmann, Jörg; Thierstein, Hans R.

Cell densities of total coccolithophores and dominant taxa were determined in 183 samples from the upper 200 m of the water column at about monthly intervals between January 1994 and August 1996 at the HOT station ALOHA, Hawaii. High cell densities were observed twice a year, in March (up to 41×10 3 cells l -1) and in September/October (up to 52×10 3 cells l -1). In the intervening months, cell densities were extremely low (0-20×10 3 cells l -1), reflecting a strong seasonality. The main production of coccolithophores took place in the middle photic zone between 50 and 100 m water depth. In total 125 coccolithophore species were identified but only five constituted on average more than 30% of the community: Emiliania huxleyi, Umbellosphaera irregularis, U. tenuis, Florisphaera profunda and Gephyrocapsa ericsonii. The generally low, but seasonally dynamic coccolithophore cell density variability is compared with in situ measurements of environmental parameters. Correlation analyses between cell density variability of the dominant taxa and potentially controlling environmental parameters show significant correlation coefficients when the data set was separated into upper and lower photic zone. Cell densities of all dominant taxa are most highly correlated with temperature variability. U. irregularis is positively correlated in the upper photic zone, whereas E. huxleyi and G. ericsonii are negatively correlated. In the lower photic zone, F. profunda cell densities are positively correlated with light, which corresponds to the maximum bottom-up control (i.e. by physical forcing) of any species encountered. The surprisingly low correlations of cell densities with nitrate and phosphate may be caused by insufficient sampling resolution, nutrient levels close to detection limits, or both.

Continuous Spectrum of Crustal Structures and Spreading Processes from Volcanic Rifted Margins to Mid-Ocean Ridges

NASA Astrophysics Data System (ADS)

Karson, J. A.

2016-12-01

Structures generated by seafloor spreading in oceanic crust (and ophiolites) and thick oceanic crust of Iceland show a continuous spectrum of features that formed by similar mechanisms but at different scales. A high magma budget near the Iceland hotspot generates thick (40-25 km) mafic crust in a plate boundary zone about 50 km wide. The upper crust ( 10 km thick) is constructed by the subaxial subsidence and thickening of lavas fed by dense dike swarms over a hot, weak lower crust to produce structures analogous to seaward-dipping reflectors of volcanic rifted margins. Segmented rift zones propagate away from the hotspot creating migrating transform fault zones, microplate-like crustal blocks and rift-parallel strike-slip faults. These structures are decoupled from the underlying lower crustal gabbroic rocks that thin by along-axis flow that reduces the overall crustal thickness and smooths-out local crustal thickness variations. Spreading on mid-ocean ridges with high magma budgets have much thinner crust (10-5 km) generated at a much narrower (few km) plate boundary zone. Subaxial subsidence accommodates the thickening of the upper crust of inward-dipping lavas and outward-dipping dikes about 1-2 km thick over a hot weak lower crust. Along-axis (high-temperature ductile and magmatic) flow of lower crustal material may help account for the relatively uniform seismic thickness of oceanic crust worldwide. Spreading along even slow-spreading mid-ocean ridges near hotspots (e.g., the Reykjanes Ridge) probably have similar features that are transitional between these extremes. In all of these settings, upper crustal and lower crustal structures are decoupled near the plate boundary but eventually welded together as the crust ages and cools. Similar processes are likely to occur along volcanic rifted margins as spreading begins.

Gravity-induced changes in intracellular potentials in elongating cortical cells of mung bean roots

NASA Technical Reports Server (NTRS)

Ishikawa, H.; Evans, M. L.

1990-01-01

Gravity-induced changes in intracellular potentials in primary roots of 2-day-old mung bean (Vigna mungo L. cv. black matpe) seedlings were investigated using glass microelectrodes held by 3-dimensional hydraulic micro-drives. The electrodes were inserted into outer cortical cells within the elongation zone. Intracellular potentials, angle of root orientation with respect to gravity, and position within the root of the impaled cortical cell were measured simultaneously. Gravistimulation caused intracellular potential changes in cortical cells of the elongation zone. When the roots were oriented vertically, the intracellular potentials of the outer cortical cells (2 mm behind the root apex) were approximately - 115 mV. When the roots were placed horizontally cortical cells on the upper side hyperpolarized to - 154 mV within 30 s while cortical cells on the lower side depolarized to about - 62 mV. This electrical asymmetry did not occur in cells of the maturation zone. Because attempts to insert the electrode into cells of the root cap were unsuccessful, these cells were not measured. The hyperpolarization of cortical cells on the upper side was greatly reduced upon application of N,N'-dicyclohexylcarbodiimide (DCCD), an inhibitor of respiratory energy coupling. When stimulated roots were returned to the vertical, the degree of hyperpolarization of cortical cells on the previous upper side decreased within 30 s and approached that of cortical cells in non-stimulated roots. This cycle of hyperpolarization/loss of hyperpolarization was repeatable at least ten times by alternately turning the root from the vertical to the horizontal and back again. The very short (<30 s) lag period of these electrical changes indicates that they may result from stimulus-perception and transduction within the elongation zone rather than from transmission of a signal from the root cap.

Light Dependence of [3H]Leucine Incorporation in the Oligotrophic North Pacific Ocean†

PubMed Central

Church, Matthew J.; Ducklow, Hugh W.; Karl, David M.

2004-01-01

The influence of irradiance on bacterial incorporation of [3H]leucine was evaluated at Station ALOHA in the oligotrophic North Pacific subtropical gyre. Six experiments were conducted on three cruises to Station ALOHA to examine how [3H]leucine incorporation varied as a function of irradiance. Two experiments were also conducted to assess the photoautotrophic response to irradiance (based on photosynthetic uptake of [14C]bicarbonate) in both the upper and lower photic zones. Rates of [3H]leucine incorporation responded to irradiance in a photosynthesis-like manner, increasing sharply at low light and then saturating and sometimes declining with increasing light intensity. The influence of irradiance on bacterial growth was evaluated in both the well-lit (5 to 25 m) and dimly lit regions of the upper ocean (75 to 100 m) to determine whether the bacterial response to irradiance differed along the depth-dependent light gradient of the photic zone. [3H]leucine incorporation rates were analyzed with a photosynthesis-irradiance model for a quantitative description of the relationships between [3H]leucine incorporation and irradiance. Maximum rates of [3H]leucine incorporation in the upper photic zone increased 48 to 92% relative to those of dark-incubated samples, with [3H]leucine incorporation saturating at light intensities between 58 and 363 μmol of quanta m−2 s−1. Rates of [3H]leucine incorporation in the deep photic zone were photostimulated 53 to 114% and were susceptible to photoinhibition, with rates declining at light intensities of >100 μmol of quanta m−2 s−1. The results of these experiments revealed that sunlight directly influences bacterial growth in this open-ocean ecosystem. PMID:15240286

Chile's seismogenic coupling zones - geophysical and neotectonic observations from the South American subduction zone prior to the Maule 2010 earthquake

NASA Astrophysics Data System (ADS)

Oncken With Tipteq, Onno; Ipoc Research Groups

2010-05-01

Accumulation of deformation at convergent plate margins is recently identified to be highly discontinuous and transient in nature: silent slip events, non-volcanic tremors, afterslip, fault coupling and complex response patterns of the upper plate during a single event as well as across several seismic cycles have all been observed in various settings and combinations. Segments of convergent plate margins with high recurrence rates and at different stages of the rupture cycle like the Chilean margin offer an exceptional opportunity to study these features and their interaction resolving behaviour during the seismic cycle and over repeated cycles. A past (TIPTEQ) and an active international initiative (IPOC; Integrated Plate Boundary Observatory Chile) address these goals with research groups from IPG Paris, Seismological Survey of Chile, Free University Berlin, Potsdam University, Hamburg University, IFM-GEOMAR Kiel, and GFZ Potsdam employing an integrated plate boundary observatory and associated projects. We focus on the south Central Chilean convergent margin and the North Chilean margin as natural laboratories embracing the recent Maule 2010 megathrust event. Here, major recent seismic events have occurred (south Central Chile: 1960, Mw = 9.5; 2010, Mw = 8.8; North Chile: 1995, Mw = 8; 2001, Mw = 8.7; 2007, Mw: 7.8) or are expected in the very near future (Iquique, last ruptured 1877, Mw = 8.8) allowing observation at critical time windows of the seismic cycle. Seismic imaging and seismological data have allowed us to relocate major rupture hypocentres and to locate the geometry of the locked zone and the degree of locking in both areas. The reflection seismic data exhibit well defined changes of reflectivity and Vp/Vs ratio along the plate interface that can be correlated with different parts of the coupling zone as well as with changes during the seismic cycle. Observations suggest an important role of the hydraulic system, an inference that is strongly supported from recent findings along the exhumed, fossil seismogenic coupling zone of the European Alps. The data provide additional evidence that the degree of interseismic locking is closely mirrored by subsequent megathrust failure as evidenced by the slip and aftershock pattern of the Maule 2010 earthquake. Neogene surface deformation in Chile has been complex exhibiting tectonically uplifting areas along the coast driven by interseismically active reverse faulting. In addition, we observe coseismically subsiding domains along other parts of the coast. Moreover, the coseismic and interseismic vertical displacement identified is not coincident with long-term vertical motion that probably is superseded by slow basal underplating or tectonic erosion occurring at the downdip parts of the seismogenic zone causing discontinuous uplift. Analogue and numerical modelling lend additional support to the kinematic patterns linking slip at the seismogenic coupling zone and upper plate response. Finally we note that the characteristic peninsulas along the South American margin constitute stable rupture boundaries/barriers and appear to have done so for a protracted time as evidenced by their long-term uplift history since at least the Late Pliocene that points to anomalous properties of the plate interface affecting the mode of strain accumulation and plate interface rupture.

Rift Zone Abandonment and Reconfiguration in Hawaii: Evidence from Mauna Loa’s Ninole Rift Zone

NASA Astrophysics Data System (ADS)

Morgan, J. K.; Park, J.; Zelt, C. A.

2009-12-01

Large oceanic volcanoes commonly develop elongate rift zones that disperse viscous magmas to the distal reaches of the edifice. Intrusion and dike propagation occur under tension perpendicular to the rift zone, controlled by topography, magmatic pressures, and deformation of the edifice. However, as volcanoes grow and interact, the controlling stress fields can change, potentially altering the orientations and activities of rift zones. This phenomenon is probably common, and can produce complex internal structures that influence the evolution of a volcano and its neighbors. However, little direct evidence for such rift zone reconfiguration exists, primarily due to poor preservation or recognition of earlier volcanic configurations. A new onshore-offshore 3-D seismic velocity model for the Island of Hawaii, derived from a joint tomographic inversion of an offshore airgun shot - onshore receiver geometry and earthquake sources beneath the island, demonstrates a complicated history of rift zone reconfiguration on Mauna Loa volcano, Hawaii, including wholesale rift zone abandonment. Mauna Loa’s southeast flank contains a massive high velocity intrusive complex, now buried beneath flows derived from Mauna Loa’s active southwest rift zone (SWRZ). Introduced here as the Ninole Rift Zone, this feature extends more than 60 km south of Mauna Loa’s summit, spans a depth range of ~2-14 km below sea level, and is the probable source of the 100-200 ka Ninole volcanics in several prominent erosional hills. A lack of high velocities beneath the upper SWRZ and its separate zone of high velocities on the submarine flank, indicate that the younger rift zone was built upon a pre-existing edifice that emanated from the Ninole rift zone. The ancient Ninole rift zone may stabilize Mauna Loa’s southeast flank, focusing recent volcanic activity and deformation onto the unbuttressed west flank. The upper portion of the Ninole rift zone appears to have migrated westward over time, possibly triggered by landsliding, causing its eventual abandonment in preference to Mauna Loa’s present-day SWRZ. Subsequently, the lower SWRZ broke away, tracking rift intrusions along the trace of the Kahuku detachment fault. Similar rift zone migration is thought to be underway at Kilauea volcano, and may one-day lead to the abandonment of the east rift zone. Such rift zone reconfiguration is a reflection of changing stress conditions within growing volcanoes. It is probably much more common than previously assumed, and may enable the growth of very large volcanic edifices such as Mauna Loa.

Lionfish (Pterois spp.) invade the upper-bathyal zone in the western Atlantic.

PubMed

Gress, Erika; Andradi-Brown, Dominic A; Woodall, Lucy; Schofield, Pamela J; Stanley, Karl; Rogers, Alex D

2017-01-01

Non-native lionfish have been recorded throughout the western Atlantic on both shallow and mesophotic reefs, where they have been linked to declines in reef health. In this study we report the first lionfish observations from the deep sea (>200 m) in Bermuda and Roatan, Honduras, with lionfish observed to a maximum depth of 304 m off the Bermuda platform, and 250 m off West End, Roatan. Placed in the context of other deeper lionfish observations and records, our results imply that lionfish may be present in the 200-300 m depth range of the upper-bathyal zone across many locations in the western Atlantic, but currently are under-sampled compared to shallow habitats. We highlight the need for considering deep-sea lionfish populations in future invasive lionfish management.

Lionfish (Pterois spp.) invade the upper-bathyal zone in the western Atlantic

USGS Publications Warehouse

Gress, Erika; Andradi-Brown, Dominic A; Woodall, Lucy; Schofield, Pam; Stanley, Karl; Rogers, Alex D.

2017-01-01

Non-native lionfish have been recorded throughout the western Atlantic on both shallow and mesophotic reefs, where they have been linked to declines in reef health. In this study we report the first lionfish observations from the deep sea (>200 m) in Bermuda and Roatan, Honduras, with lionfish observed to a maximum depth of 304 m off the Bermuda platform, and 250 m off West End, Roatan. Placed in the context of other deeper lionfish observations and records, our results imply that lionfish may be present in the 200–300 m depth range of the upper-bathyal zone across many locations in the western Atlantic, but currently are under-sampled compared to shallow habitats. We highlight the need for considering deep-sea lionfish populations in future invasive lionfish management.

Seismic evidence for a crustal magma reservoir beneath the upper east rift zoneof Kilauea volcano, Hawaii

USGS Publications Warehouse

Lin, Guoqing; Amelung, Falk; Lavallee, Yan; Okubo, Paul G.

2014-01-01

An anomalous body with low Vp (compressional wave velocity), low Vs (shear wave velocity), and high Vp/Vs anomalies is observed at 8–11 km depth beneath the upper east rift zone of Kilauea volcano in Hawaii by simultaneous inversion of seismic velocity structure and earthquake locations. We interpret this body to be a crustal magma reservoir beneath the volcanic pile, similar to those widely recognized beneath mid-ocean ridge volcanoes. Combined seismic velocity and petrophysical models suggest the presence of 10% melt in a cumulate magma mush. This reservoir could have supplied the magma that intruded into the deep section of the east rift zone and caused its rapid expansion following the 1975 M7.2 Kalapana earthquake.

Saline-water intrusion related to well construction in Lee County, Florida

USGS Publications Warehouse

Boggess, Durward Hoye; Missimer, T.M.; O'Donnell, T. H.

1977-01-01

Ground water is the principle source of water supply in Lee County, Florida where an estimated 30,000 wells have been drilled since 1990. These wells ranges in depth from about 10 to 1,240 feet and tap the water table aquifer or one or more of the artesian water-bearing units or zones in the Tamiami Formation, the upper part of the Hawthorn Formation, the lower part of the Hawthorn Formation and the Tampa Limestone and the Suwannee Limestone. Before 1968, nearly all wells were constructed with galvanized or black iron pipe. Many of these wells are sources of saline-water intrusion into freshwater-bearing zones. The water-bearing zones in the lower part of the Hawthorn Formation, Tampa Limestone, and Suwannee Limestone are artesian-they have higher water levels and usually contain water with a higher concentration of dissolved solids than do the aquifers occurring at shallower depths. The water from these deeper aquifers generally range in dissolved solids concentration from about 1,500 to 2,400 mg/L, and in chloride from about 500 to 1,00 mg/L. A maximum chloride concentration of 15,200 mg/L has been determined. Few of the 3,00 wells estimated to have been drilled to these zones contain sufficient casing to prevent upward flow into overlaying water-bearing zones. Because of water-level differentials, upward movement and lateral intrusion of saline water occurs principally into the upper part of the Hawthorn Formation where the chloride concentrations in water unaffected by saline-water intrusion ranges from about 80 to 150 mg/L. Where intrusion from deep artesian zones has occurred, the chloride concentration in water from the upper part of the Hawthorn Formation ranges from about 300 to more than 2,100 mg/L Surface discharges of the saline water from wells tapping the lower part of the Hawthorn Formation and the Suwannee Limestone also had affected the water-table aquifer which normally contains water with 10 to 50 mg/L of chloride. In one area, the chloride concentration in water from the water table aquifer ranged from 200 to 590 mg/L as a result of intrusion. In areas adjacent to tidal-water bodies, the water table aquifer contains water that is very saline, Where the wells in such areas have been constructed with metal casings, the metal corrodes when exposed to the saline water, and many ultimately develop holes. This permits saline water to leak into the well where the water level in the well is lower than the water table. The intrusion of saline water from the water-table aquifer into the upper part of the Hawthorn Formation is a major problem in parts of Cape Coral. Withdrawal of water from the upper part of the Hawthorn Formation has caused water levels to decline below the lowest annual position of the water table, so that downward leakage is perennial. In some coastal areas, wells that tap the upper part of the Hawthorn Formation contain water whose chloride concentration is as much as 9,500 mg/L. Upward leakage of saline water from the deep artesian aquifers and downward leakage of saline water from the water-table aquifer can be prevented by proper well construction.

Imaging the seismic structure beneath oceanic spreading centers using ocean bottom geophysical techniques

NASA Astrophysics Data System (ADS)

Zha, Yang

This dissertation focuses on imaging the crustal and upper mantle seismic velocity structure beneath oceanic spreading centers. The goals are to provide a better understanding of the crustal magmatic system and the relationship between mantle melting processes, crustal architecture and ridge characteristics. To address these questions I have analyzed ocean bottom geophysical data collected from the fast-spreading East Pacific Rise and the back-arc Eastern Lau Spreading Center using a combination of ambient noise tomography and seafloor compliance analysis. To characterize the crustal melt distribution at fast spreading ridges, I analyze seafloor compliance - the deformation under long period ocean wave forcing - measured during multiple expeditions between 1994 and 2007 at the East Pacific Rise 9º - 10ºN segment. A 3D numerical modeling technique is developed and used to estimate the effects of low shear velocity zones on compliance measurements. The forward modeling suggests strong variations of lower crustal shear velocity along the ridge axis, with zones of possible high melt fractions beneath certain segments. Analysis of repeated compliance measurements at 9º48'N indicates a decrease of crustal melt fraction following the 2005 - 2006 eruption. This temporal variability provides direct evidence for short-term variations of the magmatic system at a fast spreading ridge. To understand the relationship between mantle melting processes and crustal properties, I apply ambient noise tomography of ocean bottom seismograph (OBS) data to image the upper mantle seismic structure beneath the Eastern Lau Spreading Center (ELSC). The seismic images reveal an asymmetric upper mantle low velocity zone (LVZ) beneath the ELSC, representing a zone of partial melt. As the ridge migrates away from the volcanic arc, the LVZ becomes increasingly offset and separated from the sub-arc low velocity zone. The separation of the ridge and arc low velocity zones is spatially coincident with the abrupt transition in crustal composition and ridge morphology. Therefore these results confirm a previous prediction that the changing interaction between the arc and back-arc magmatic systems is responsible for the abrupt change in crustal properties along the ELSC. I further investigate the crustal structure along and across the ELSC using seafloor compliance. Compliance measurements are inverted for local crustal shear velocity structure as well as sediment thickness at 30 OBS locations using a Monte Carlo method. Sediment increases asymmetrically with seafloor age, with much a higher rate to the east of the ridge. Along the ELSC, upper crustal velocities increase from south to north as the ridge migrates away from the volcanic arc front, consistent with a less porous upper crust with possibly less subduction input. Furthermore, average upper crust shear velocities for crust produced at past ELSC when it was near the volcanic arc are considerably slower than crust produced at present day northern ELSC. I show that the implications of previous active seismic studies in the axial ELSC can be extended much farther off-axis and back in time. I also address a challenge of ocean bottom seismology and develop a new method for determining OBS horizontal orientations using multi-component ambient noise correlation. I demonstrate that the OBS orientations can be robustly estimated through maximizing the correlation between the diagonal and cross terms of the noise correlation function. This method is applied to the ELSC OBS experiment dataset and the obtained orientations are consistent with results from a conventional teleseismic method. The new method is promising for a wide range of applications.

Geochemistry of NE Atlantic non-rifting zones, Iceland and Jan Mayen

NASA Astrophysics Data System (ADS)

Tronnes, R. G.; Waight, T.

2005-12-01

The fertile components of the NE Atlantic mantle are sampled preferentially by alkaline basalts in the volcanic flank zones of Iceland and in the Jan Mayen and Vesteris seamount areas. Our data from primitive flank zone lavas from Iceland and Jan Mayen demonstrate a HIMU-affinity with enrichment of HFSE, U/Pb, Th/U and Nb/Th. In PM-normalized spider diagrams the least enriched samples have weakly positive Sr-anomalies, whereas the most enriched samples have negative Sr-anomalies. The entire sample suite shows negative Sr-Nd-isotope correlation, whereas the samples of each volcanic system or flank zone generally lack such a correlation. Our data confirm the anomalously high 87/86Sr of the Orafajokull volcanic system in the eastern flank zone. The results are consistent with existing data for other primitive flank zone basalts from Iceland and Jan Mayen. Common geochemical features linking alkaline flank zone basalts and high-degree tholeiitic melts include high 87/86Sr (and probably 176/177Hf) for a given 143/144Nd, negative delta-207Pb (except for Orafajokull) and positive delta-Nb. Alkaline flank zone basalts have generally higher 87/86Sr, 206/204Pb and 18/16O and lower 143/144Nd, 187/188Os and 3/4He than rift zone tholeiites. The different 18/16O ratios in flank and rift zone basalts are consistent with seafloor hydrothermal alteration of the upper and lower parts of recycled oceanic lithosphere, respectively. Olivine-melt fractionation may contribute to the difference. Indications of lower 187/188Os in alkaline basalts compared to nearby rift zone tholeiites could be caused by subduction zone loss of Re from the upper part of recycled slabs. The partial melting and volcanic sampling of the fertile mantle components under Iceland and the NE Atlantic is governed by the crustal structure and geometry of the Icelandic volcanic zones and the lateral deflection of the upwelling heterogeneous mantle source originating under central Iceland. Based on the pattern of V-shaped ridges along the Kolbeinsey ridge, the lateral mantle flow from central Iceland may well extend beyond Jan Mayen. The geochemical similarities between the enriched basalts of the Icelandic flank zones and Jan Mayen support this contention, although a minor separate plume under JM is a possibility.

Subduction zone decoupling/retreat modeling explains south Tibet (Xigaze) and other supra-subduction zone ophiolites and their UHP mineral phases

NASA Astrophysics Data System (ADS)

Butler, Jared P.; Beaumont, Christopher

2017-04-01

The plate tectonic setting in which proto-ophiolite 'oceanic' lithosphere is created remains controversial with a number of environments suggested. Recent opinions tend to coalesce around supra-subduction zone (SSZ) forearc extension, with a popular conceptual model in which the proto-ophiolite forms during foundering of oceanic lithosphere at the time of spontaneous or induced onset of subduction. This mechanism is favored in intra-oceanic settings where the subducting lithosphere is old and the upper plate is young and thin. We investigate an alternative mechanism; namely, decoupling of the subducting oceanic lithosphere in the forearc of an active continental margin, followed by subduction zone (trench) retreat and creation of a forearc oceanic rift basin, containing proto-ophiolite lithosphere, between the continental margin and the retreating subduction zone. A template of 2D numerical model experiments examines the trade-off between strength of viscous coupling in the lithospheric subduction channel and net slab pull of the subducting lithosphere. Three tectonic styles are observed: 1) C, continuous subduction without forearc decoupling; 2) R, forearc decoupling followed by rapid subduction zone retreat; 3) B, breakoff of subducting lithosphere followed by re-initiation of subduction and in some cases, forearc decoupling (B-R). In one case (BA-B-R; where BA denotes backarc) subduction zone retreat follows backarc rifting. Subduction zone decoupling is analyzed using frictional-plastic yield theory and the Stefan solution for the separation of plates containing a viscous fluid. The numerical model results are used to explain the formation of Xigaze group ophiolites, southern Tibet, which formed in the Lhasa terrane forearc, likely following earlier subduction and not necessarily during subduction initiation. Either there was normal coupled subduction before subduction zone decoupling, or precursor slab breakoff, subduction re-initiation and then decoupling. Rapid deep upper-mantle circulation in the models during subduction zone retreat can exhume and emplace material in the forearc proto-ophiolite from as deep as the mantle transition zone, thereby explaining diamonds and other 10-15 GPa UHP phases in Tibetan ophiolites.

Seismic Characterization of Oceanic Water Masses, Water Mass Boundaries, and Mesoscale Eddies SE of New Zealand

NASA Astrophysics Data System (ADS)

Gorman, Andrew R.; Smillie, Matthew W.; Cooper, Joanna K.; Bowman, M. Hamish; Vennell, Ross; Holbrook, W. Steven; Frew, Russell

2018-02-01

The Subtropical and Subantarctic Fronts, which separate Subtropical, Subantarctic, and Antarctic Intermediate Waters, are diverted to the south of New Zealand by the submerged continental landmass of Zealandia. In the upper ocean of this region, large volumes of dissolved or suspended material are intermittently transported across the Subtropical Front; however, the mechanisms of such transport processes are enigmatic. Understanding these oceanic boundaries in three dimensions generally depends on measurements collected from stationary vessels and moorings. The details of these data sets, which are critical for understanding how water masses interact and mix at the fine-scale (<10 m) to mesoscale (10-100 km), are inadequately constrained due to resolution considerations. Southeast of New Zealand, high-resolution seismic reflection images of oceanic water masses have been produced using petroleum industry data. These seismic sections clearly show three main water masses, the boundary zones (fronts) between them, and associated thermohaline fine structure that may be related to the mixing of water masses in this region. Interpretations of the data suggest that the Subtropical Front in this region is a landward-dipping zone, with a width that can vary between 20 and 40 km. The boundary zone between Subantarctic Waters and the underlying Antarctic Intermediate Waters is also observed to dip landward. Several isolated lenses have been identified on the three data sets, ranging in size from 9 to 30 km in diameter. These lenses are interpreted to be mesoscale eddies that form at relatively shallow depths along the south side of the Subtropical Front.

Modeling tritium transport through a deep unsaturated zone in an arid environment

USGS Publications Warehouse

Mayers, C.J.; Andraski, Brian J.; Cooper, C.A.; Wheatcraft, S.W.; Stonestrom, David A.; Michel, R.L.

2005-01-01

Understanding transport of tritium (3H) in unsaturated zones is critical to evaluating options for waste isolation. Tritium typically is a large component of low-level radioactive waste (LLRW). Studies at the U.S. Geological Survey's Amargosa Desert Research Site (ADRS) in Nevada investigate 3H transport from a closed LLRW facility. Two boreholes are 100 and 160 m from the nearest waste trench and extend to the water table at 110 m. Soil-water vapor samples from the deep boreholes show elevated levels of 3H at all depths. The objectives of this study were to (i) test source thermal and gas-advection mechanisms driving 3H transport and (ii) evaluate model sensitivity to these mechanisms and to selected physical and hydraulic properties including porosity, tortuosity, and anisotropy. A two-dimensional numerical model incorporated a non-isothermal, heterogeneous domain of the unsaturated zone and instantaneous isotopic equilibrium. The TOUGH2 code was used; however, it required modification to account for temperature dependence of both the Henry's law equilibrium constant and isotopic fractionation with respect to tritiated water. Increases in source temperature, pressure, and porosity enhanced 3H migration, but failed to match measured 3H distributions. All anisotropic simulations with a source pressure component resembled, in shape, the upper portion of the 3H distribution of the nearest borehole. Isotopic equilibrium limited migration of 3H, while effects of radioactive decay were negligible. A 500 Pa pressure increase above ambient pressure in conjunction with a high degree of anisotropy (1:100) was necessary for simulated 3H transport to reach the nearest borehole.

CO2 concentration and occupancy density in the critical zones served by the VAV system

NASA Astrophysics Data System (ADS)

Etoua Evina, Ghislaine; Kajl, Stanislaw; Lamarche, Louis; Beltran-Galindo, Javier

2017-11-01

This article presents the results obtained from monitoring a VAV system with highly diversified zone occupancy density are presented in the article. The investigated VAV system meets the load for 72 zones (68 perimeters and 4 interiors) consisting of classrooms, offices, conference rooms, etc. with highly diversified occupancy densities from 1.875 to 2.5 m2/person for the classrooms and from 10 to 15 m2/person for the offices. The monitoring shows that the CO2 concentration can exceed the set point in the critical rooms. Simulation results are also presented in the article to show that it is often impossible to adjust the operation of such VAV systems because the adjusted System Outdoor Air Fractions, % OA, can reach 100% even where the zone CO2 concentration is not respected. The presented monitoring and simulation results were obtained in the winter, with the VAV system operating at partial load and with the minimum outdoor air flowrate required by the economizer system. As shown in the article, to respect the zone set point CO2 concentration in such period, the VAV system must operate mostly at a %OA equal to 100% instead of its minimum value. To circumvent this, the supply zone air flow rate may have to be designed taking into account the CO2 concentration resulting from the critical zones occupancy density.

The benthic fauna from the lower Maastrichtian chalk of Kronsmoor (Saturn quarry, northern Germany): composition and palaeoecologic implications

NASA Astrophysics Data System (ADS)

Engelke, Julia; Linnert, Christian; Mutterlose, Jörg; Wilmsen, Markus

2017-04-01

The Saturn quarry near Kronsmoor (northern Germany) offers an undisturbed section of upper Campanian to lower Maastrichtian chalks. The target interval of the DFG project "Biodiversity and plankton-benthos coupling: an integrated ecosystem analysis from the Late Cretaceous Chalk" is focused on the lower Maastrichtian Belemnella obtusa Zone to mid-Belemnella sumensis Zone, i.e. to the uppermost Kronsmoor and lowermost Hemmoor formations. In this interval, a conspicuous increase in macrofossil abundance without apparent lithofacies changes has been observed and the project intends to integrate planktic, benthic and geochemical proxies for a comprehensive understanding of the Chalk Sea ecosystem. The aim of this study is the analysis of the benthic community. In a first step, the benthic body fossils of the c. 25-m-thick section were semi-quantitatively studied based on a collection of more than 1,000 specimens. Two successive benthic macrofossil assemblages were recognised: the lower interval (upper part of the Kronsmoor Formation, B. obtusa Zone) is characterized by low abundances, only about 100 macroinvertebrates were collected, mostly irregular and regular echinoids, brachiopods and crinoids. The upper interval (B. sumensis Zone) shows an eight times higher macroinvertebrate abundance and a conspicuous dominance of brachiopods, increasing from only 30 to over 500 specimens. In order to quantify the observed qualitative palaeoecological changes, 33 bulk samples of about 6 kg each were retrieved in a distance of c. 0.75 m. The bulk samples were frozen and thawed, washed and sieved in different sizes. The fraction 500 μm-1 mm and >1 mm were picked, sorted and counted. A diverse assemblage of bryozoans, foraminifers, shell fragments of brachiopods and bivalves, spines and test fragments of different echinoid taxa, parts of asteroids and ophiuroids, sponge debris, crinoids and small serpulids, is present. Reduced abundances in the lower part and generally higher abundances in the upper part are recognised. The palaeoecological analysis of both datasets indicates different guilds, of which epifaunal suspension feeders (fixo-sessile and libero-sessile guilds), comprising c. 50 % of the fauna in the lower interval, increase to a dominance of c. 80 % in the upper interval, including a considerable proportion of rhynchonelliform brachiopods. The palaeoecological data of benthic communities at Kronsmoor are indicative of increased nutrient availability during the early Maastrichtian. However, in the absence of any evidence of increased productivity in the overlying photic zone (calcareous nannofossil data), a lateral input (upwelling) of nutrient-rich waters onto the shelf to fuel the benthic ecosystem has to be considered. This view is supported by records of contemporaneous changes in latest Cretaceous ocean circulation that followed the latest Campanian cooling event, inclusive of a southward spread of waters of intermediate depth from high-latitudes.

Alder Establishment and Channel Dynamics in a Tributary of the South Fork Eel River, Mendocino County, California

Treesearch

William J. Trush; Edward C. Connor; Knight Alan W.

1989-01-01

Riparian communities established along Elder Creek, a tributary of the upper South Fork Eel River, are bounded by two frequencies of periodic flooding. The upper limit for the riparian zone occurs at bankfull stage. The lower riparian limit is associated with a more frequent stage height, called the active channel, having an exceedance probability of 11 percent on a...

Upper-mantle origin of the Yellowstone hotspot

USGS Publications Warehouse

Christiansen, R.L.; Foulger, G.R.; Evans, J.R.

2002-01-01

Fundamental features of the geology and tectonic setting of the northeast-propagating Yellowstone hotspot are not explained by a simple deep-mantle plume hypothesis and, within that framework, must be attributed to coincidence or be explained by auxiliary hypotheses. These features include the persistence of basaltic magmatism along the hotspot track, the origin of the hotspot during a regional middle Miocene tectonic reorganization, a similar and coeval zone of northwestward magmatic propagation, the occurrence of both zones of magmatic propagation along a first-order tectonic boundary, and control of the hotspot track by preexisting structures. Seismic imaging provides no evidence for, and several contraindications of, a vertically extensive plume-like structure beneath Yellowstone or a broad trailing plume head beneath the eastern Snake River Plain. The high helium isotope ratios observed at Yellowstone and other hotspots are commonly assumed to arise from the lower mantle, but upper-mantle processes can explain the observations. The available evidence thus renders an upper-mantle origin for the Yellowstone system the preferred model; there is no evidence that the system extends deeper than ???200 km, and some evidence that it does not. A model whereby the Yellowstone system reflects feedback between upper-mantle convection and regional lithospheric tectonics is able to explain the observations better than a deep-mantle plume hypothesis.

Conodont biostratigraphy from the upper San Juan Formation (Middle Ordovician) at Niquivil, Argentine Precordillera

NASA Astrophysics Data System (ADS)

Mango, M. J.; Albanesi, G. L.

2018-07-01

The present work deals with the conodont biostratigraphy from the upper San Juan Formation in the section of Niquivil, Central Precodillera of San Juan, Argentina. We study the upper 129.45 m of the San Juan Formation, starting from the upper strata of the second reef horizon up to the top of the formation. Digested limestone samples yielded 20 conodont species. The presence of Tripodus laevis Bradshaw not associated to Baltoniodus navis (Lindström) allows the recognition of the Baltoniodus triangularis-Tripodus laevis Zone, which is interpreted as correlative with the "Parapanderodus" nogamii/Parapanderodus gracilis/Ansella jemtlandica Association of Lehnert (1993, 1995; Lehnert and Keller, 1993), conversely to previous interpretations that suggested the latter as correlative to the Baltoniodus navis Zone. The zonal identification is supported by the associated conodonts Protopanderodus rectus (Lindström), Juanognathus jaanussoni Serpagli, Juanognathus n. sp., Protopanderodus gradatus (Serpagli), Rossodus barnesi Albanesi, Paltodus subaequalis Pander, Drepanodus arcuatus (Pander), Cornuodus longibasis (Lindström), Protopanderodus elongatus Serpagli, Oistodus lanceolatus Pander, Periodon flabellum (Lindström), Semiacontiodus potrerillensis Albanesi, Triangulodus brevibasis (Sergeeva), Paroistodus originalis (Sergeeva), Drepanoistodus forceps (Lindström), Oistodus multicorrugatus Harris, Parapanderodus paracornuformis (Ethington and Clark), Anodontus longus Stouge and Bagnoli, and Pteracontiodus cryptodens Mound. The petrographic microscope analysis of carbonate rocks thin sections refer to proximal middle ramp deposits.

The Middle Jurassic microflora from El Maghara N° 4 borehole, Northern Sinai, Egypt

NASA Astrophysics Data System (ADS)

Mohsen, Sayed Abdel

The coal bearing formation in El Maghara area, northern Sinai, yielded abundant, diverse and generally well preserved spores, pollen and marine microflora. The palynological analysis of the fine clastic sediments in this formation yielded (71) species related to (44) genera. Three different palynological assemblage zones can be distinguished. The sediments which contain lower and the upper assemblage zones bearing the coal seems, were deposited in non-marine (swamp) environment. In the middle assemblage zone few marine microflora can be identified, indicating a coastal near shore marine environment. Compared with other palynologic data obtained from Egypt and other countries, the three described assemblage zones belong to Middle Jurassic (Bathonian) age.

Seismic-wave attenuation associated with crustal faults in the New Madrid seismic zone

USGS Publications Warehouse

Hamilton, R.M.; Mooney, W.D.

1990-01-01

The attenuation of upper crustal seismic waves that are refracted with a velocity of about 6 kilometers per second varies greatly among profiles in the area of the New Madrid seismic zone in the central Mississippi Valley. The waves that have the strongest attenuation pass through the seismic trend along the axis of the Reelfoot rift in the area of the Blytheville arch. Defocusing of the waves in a low-velocity zone and/ or seismic scattering and absorption could cause the attenuation; these effects are most likely associated with the highly deformed rocks along the arch. Consequently, strong seismic-wave attenuation may be a useful criterion for identifying seismogenic fault zones.

Note on seismic hazard assessment using gradient of uplift velocities in the Turan block (Central Asia)

NASA Astrophysics Data System (ADS)

Jaboyedoff, M.; Derron, M.-H.; Manby, G. M.

2005-01-01

Uplift gradients can provide the location of highly strained zones, which can be considered to be seismic. The Turan block (Central Asia) contains zones with high gradient of uplift velocities, above the threshold 0.04mm km-1year-1. Some of these zones are associated with important seismic activity and others are not correlated with any recent important recorded earthquakes, however, recent faults scarps as well as diverted rivers may indicate a recent tectonic activity. This threshold of gradient is probably a significant rheologic property of the upper crust. On the basis of these considerations the Uzboy river area is proposed as a potential high seismic hazard zone.

Linking Weathering, Rock Moisture Dynamics, Geochemistry, Runoff, Vegetation and Atmospheric Processes through the Critical Zone: Graduate Student led Research at the Eel River Critical Zone Observatory

NASA Astrophysics Data System (ADS)

Dietrich, W. E.

2014-12-01

In the Eel River Critical Zone Observatory lies Rivendell, a heavily-instrumented steep forested hillslope underlain by nearly vertically dipping argillite interbedded with sandstone. Under this convex hillslope lies "Zb", the transition to fresh bedrock, which varies from less than 6 m below the surface near the channel to 20 m at the divide. Rempe and Dietrich (2014, PNAS) show that the Zb profile can be predicted from the assumption that weathering occurs when drainage is induced in the uplifting fresh bedrock under hillslopes by lateral head gradients driven by channel incision at the hillslope boundary. Infiltrating winter precipitation is impeded at the lower conductivity boundary at Zb, generating perched groundwater that dynamically pulses water laterally to the channel, controlling stream runoff. Below the soil and above the water table lies an unsaturated zone through which all recharge to the perched groundwater (and thus all runoff to channels) occurs. It is this zone and the waters in them that profoundly affect critical zone processes. In our seasonally dry environment, the first rains penetrate past the soil and moisten the underlying weathered bedrock (Salve et al., 2012, WRR). It takes about 200 to 400 mm of cumulative rain, however, before the underlying groundwater rises significantly. Oshun et al (in review) show that by this cumulative rainfall the average of the wide-ranging isotopic signature of rain reaches a nearly constant average annual value. Consequently, the recharging perched groundwater shows only minor temporal isotopic variation. Kim et al, (2014, GCA) find that the winter high-flow groundwater chemistry is controlled by relatively fast-reacting cation exchange processes, likely occurring in transit in the unsaturated zone. Oshun also demonstrates that the Douglas fir rely on this rock moisture as a water source, while the broadleaf trees (oaks and madrone) use mostly soil moisture. Link et al (2014 WRR) show that Doug fir declines in transpiration rate significantly compared to the madrone during summer high water stress periods, with may induce feedbacks from the forest to atmospheric temperature and humidity. Collectively these studies spotlight the seasonally dynamic unsaturated zone in the weathered bedrock beneath the soil as key to understanding critical zone processes.

The large-scale structure of the asteroid belt

NASA Technical Reports Server (NTRS)

Zellner, B.; Thirunagari, A.; Bender, D.

1985-01-01

The distributions of 2888 numbered minor planets over orbital inclination, eccentricity, and semimajor axis are examined, and 19 zones believed to adequately isolate the selection biases in survey programs of the physical properties of minor planets are defined. Six numbered asteroids have exceptional orbits and fall into no zone. Attention is called to rather sharp upper limits, which become increasingly stringent at larger heliocentric distances, on orbital inclinations and eccentricity.

The Seismic Attenuation Structure of the East Pacific Rise

DTIC Science & Technology

1992-02-27

Kanamori, R. W. Clayton, Three- dimensional attenuation structure of Kilauea -East rift zone, Hawaii , J. Geophys. Res., submitted, 1990. Holt, M., Underwater...and J. J. Zucca, Active high-resolution seismic tomography of compressional wave velocity and attenuation at Medicine Lake volcano , northern California...zones of anomalously high S-wave attenuation in the upper crust near Ruapehu and Ngauruhoe volcanoes , New Zealand, J. Volcanol. Geotherm. Res., 10, 125

Age of amphibolites associated with alpine peridotites in the Dinaride ophiolite zone, Yugoslavia

USGS Publications Warehouse

Lanphere, M.A.; Coleman, R.G.; Karamata, S.; Pamic, J.

1975-01-01

Amphibolites associated with alpine peridotites in the Central Ophiolite zone in Yugoslavia have K-Ar ages of 160-170 m.y. These amphibolites and associated peridotites underwent deep-seated metamorphism prior to tectonic emplacement into the sedimentary-volcanic assemblage of the Dinarides. The alpine peridotites and associated local rocks of the ophiolite suite are interpreted as Jurassic oceanic crust and upper mantle. ?? 1975.

The Effects of Affirmative Quality Feedback on Low Socio-Economic Students' Zone of Proximal Development Reading Gains (ZPDRL): A Causal-Comparative Study

ERIC Educational Resources Information Center

Prescott, Sharon H.

2010-01-01

The purpose of this study was to explore upper elementary reading classes in a low socio-economic area to determine the effects frequent praise, both academically and socially, have on the zone of proximal development in reading (ZPD[subscript RL], Renaissance Learning, 2006). A causal-comparative study was utilized by observing two groups of…

Underplating along the northern portion of the Zagros suture zone, Iran

NASA Astrophysics Data System (ADS)

Motaghi, K.; Shabanian, E.; Kalvandi, F.

2017-07-01

A 2-D absolute shear wave velocity model has been resolved beneath a seismic profile across the northeastern margin of the Arabian Plate-Central Iran by simultaneously inverting data from P receiver functions and fundamental mode Rayleigh wave phase velocity. The data were gathered by a linear seismic array crossing the Zagros fold and thrust belt, Urmia-Dokhtar magmatic arc and Central Iran block assemblage as three major structural components of the Arabia-Eurasia collision. Our model shows a low-velocity tongue protruding from upper to lower crust which, north of the Zagros suture, indicates the signature of an intracontinent low-strength shear zone between the underthrusting and overriding continents. The velocity model confirms the presence of a significant crustal root as well as a thick high-velocity lithosphere in footwall of the suture, continuing northwards beneath the overriding continent for at least 200 km. These features are interpreted as underthrusting of Arabia beneath Central Iran. Time to depth migration of P receiver functions reveals an intracrustal flat interface at ∼17 km depth south of the suture; we interpret it as a significant decoupling within the upper crust. All these crustal scale structural features coherently explain different styles and kinematics of deformation in northern Zagros (Lorestan zone) with respect to its southern part (Fars zone).

Subducting plate geology in three great earthquake ruptures of the western Alaska margin, Kodiak to Unimak

USGS Publications Warehouse

von Huene, Roland E.; Miller, John J.; Weinrebe, Wilhelm

2012-01-01

Three destructive earthquakes along the Alaska subduction zone sourced transoceanic tsunamis during the past 70 years. Since it is reasoned that past rupture areas might again source tsunamis in the future, we studied potential asperities and barriers in the subduction zone by examining Quaternary Gulf of Alaska plate history, geophysical data, and morphology. We relate the aftershock areas to subducting lower plate relief and dissimilar materials in the seismogenic zone in the 1964 Kodiak and adjacent 1938 Semidi Islands earthquake segments. In the 1946 Unimak earthquake segment, the exposed lower plate seafloor lacks major relief that might organize great earthquake rupture. However, the upper plate contains a deep transverse-trending basin and basement ridges associated with the Eocene continental Alaska convergent margin transition to the Aleutian island arc. These upper plate features are sufficiently large to have affected rupture propagation. In addition, massive slope failure in the Unimak area may explain the local 42-m-high 1946 tsunami runup. Although Quaternary geologic and tectonic processes included accretion to form a frontal prism, the study of seismic images, samples, and continental slope physiography shows a previous history of tectonic erosion. Implied asperities and barriers in the seismogenic zone could organize future great earthquake rupture.

Metamorphic and tectonic evolution of the Greater Himalayan Crystalline Complex in Nyalam region, south Tibet

NASA Astrophysics Data System (ADS)

Wang, Jia-Min; Zhang, Jin-Jiang; Rubatto, Daniela

2016-04-01

Recent studies evoke dispute whether the Himalayan metamorphic core - Greater Himalayan Crystalline Complex (GHC) - was exhumed as a lateral crustal flow or a critical taper wedge during the India-Asia collision. This contribution investigated the evolution of the GHC in the Nyalam region, south Tibet, with comprehensive studies on structural kinematics, metamorphic petrology and geochronology. The GHC in the Nyalam region can be divided into the lower and upper GHC. Phase equilibria modelling and conventional thermobarometric results show that peak temperature conditions are lower in the lower GHC (~660-700°C) and higher in the upper GHC (~740-780°C), whereas corresponding pressure conditions at peak-T decrease from ~9-13 kbar to ~4 kbar northward. Monazite, zircon and rutile U-Pb dating results reveal two distinct blocks within the GHC of the Nyalam region. The upper GHC underwent higher degree of partial melting (15-25%, via muscovite dehydration melting) that initiated at ~32 Ma, peaked at ~29 Ma to 25 Ma, possibly ended at ~20 Ma. The lower GHC underwent lower degree of melting (0-10%) that lasted from 19 to 16 Ma, which was produced mainly via H2O-saturated melting. At different times, both the upper and lower blocks underwent initial slow cooling (35 ± 8 and 10 ± 5°C/Myr, respectively) and subsequent rapid cooling (120 ± 40°C/Myr). The established timescale of metamorphism suggests that high-temperature metamorphism within the GHC lasted a long duration (~15 Myr), whereas duration of partial melting lasted for ~3 Myr in the lower GHC and lasted for 7-12 Myr in the upper GHC. The documented diachronous metamorphism and discontinuity of peak P-T conditions implies the presence of the Nyalam Thrust in the study area. This thrust is probably connected to the other thrusts in Nepal and Sikkim Himalaya, which extends over ~800 km and is named the "High Himalayan Thrust". Timing of activity along this thrust is at ~25-16 Ma, which is coeval with active timing along the South Tibetan detachment (27-16 Ma) but precedes that along the MCT (16-10 Ma). Comparison between the obtained P-T-t data and model predictions implies that a lateral crustal flow process dominated the exhumation of the high-grade upper GHC migmitites during 25-16 Ma, whereas a critical taper thrusting process dominated the exhumation of the MCT zone nonmigmatites and cooled migmatites in the lower GHC at 16-10 Ma. In other words, at different temporal and spatial scale, both propagating thrusting along large tectonic boundaries and a low-viscosity melting crust could contribute to the exhumation of high-grade metamorphic rocks in Himalaya-like large hot collisional orogens. KEY WORDS: Greater Himalayan Crystalline Complex; P-T path; U-Pb geochronology; channel flow; tectonic discontinuity References: Wang, J.M., Rubatto, D., Zhang, J.J., 2015a. Timing of partial melting and cooling across the Greater Himalayan Crystalline Complex (Nyalam, central Himalaya): in-sequence thrusting and its implications. Journal of Petrology, 56, 1677-1702. Wang, J.M., Zhang, J.J., Wei, C.J., Rai, S.M., Wang, M., Qian, J.H., 2015b. Characterizing the metamorphic discontinuity across the Main Central Thrust Zone of eastern-central Nepal. Journal of Asian Earth Sciences 101, 83-100. Wang, J.M., Zhang, J.J., Wang, X.X., 2013. Structural kinematics, metamorphic P-T profiles and zircon geochronology across the Greater Himalayan Crystalline Complex in south-central Tibet: implication for a revised channel flow. Journal of Metamorphic Geology 31, 607-628.

Microbiostratigraphy of the Upper Paleocene to Middle Eocene Jahrum Formation in the Folded Zagros Zone, SW Iran

NASA Astrophysics Data System (ADS)

Izadighalati, S.; Ahmadi, V.

2017-12-01

The Jahrum Formation (Upper Paleocene to Middle Eocene) is composed of carbonate and dolomitic carbonate rocks in the Zagros Basin. The Zagros is located at the boundary between the Arabian and Eurasian lithosphere plates and represent the orogenic response to a collision between Eurasia and advancing Arabia during the Cenozoic. The study area is located in the northern part of Kuh-E-Tudej, 175 km southeast of Shiraz in the Folded Zagros Zone. The Jahrum Formation at Kuh-E-Tudej, with a thickness of 190 m, consists of medium to massive bedded limestone. The following foraminiferal index species are identified in the studied section: Fallotella alavensis, Kathina sp., Miscellanea sp., Lockhartia sp., Orbitolites shirazeinsis, Nummulites sp., Opertorbitolites sp., Dictyoconus cf. egyptiensis, Orbitolites cf. complanatus, Dictyoconus sp., Coskinolina sp., Somalina stefaninii, Discocyclina sp., Praerhapydionina sp., Coskinolina cf. liburnica, Nummulites cf. globulus, Nummulites cf. aturicus, and Alveolina sp. The age of the studied sediments ranges from Upper Paleocene to Middle Eocene. The microbiostratigraphic studies revealed four biozones based on the foraminifers identified in the studied section.

Time-Varying Upper-Plate Deformation during the Megathrust Subduction Earthquake Cycle

NASA Astrophysics Data System (ADS)

Furlong, Kevin P.; Govers, Rob; Herman, Matthew

2015-04-01

Over the past several decades of the WEGENER era, our abilities to observe and image the deformational behavior of the upper plate in megathrust subduction zones has dramatically improved. Several intriguing inferences can be made from these observations including apparent lateral variations in locking along subduction zones, which differs from interseismic to coseismic periods; the significant magnitude of post-earthquake deformation (e.g. following the 20U14 Mw Iquique, Chile earthquake, observed on-land GPS post-EQ displacements are comparable to the co-seismic displacements); and incompatibilities between rates of slip deficit accumulation and resulting earthquake co-seismic slip (e.g. pre-Tohoku, inferred rates of slip deficit accumulation on the megathrust significantly exceed slip amounts for the ~ 1000 year recurrence.) Modeling capabilities have grown from fitting simple elastic accumulation/rebound curves to sparse data to having spatially dense continuous time series that allow us to infer details of plate boundary coupling, rheology-driven transient deformation, and partitioning among inter-earthquake and co-seismic displacements. In this research we utilize a 2D numerical modeling to explore the time-varying deformational behavior of subduction zones during the earthquake cycle with an emphasis on upper-plate and plate interface behavior. We have used a simplified model configuration to isolate fundamental processes associated with the earthquake cycle, rather than attempting to fit details of specific megathrust zones. Using a simple subduction geometry, but realistic rheologic layering we are evaluating the time-varying displacement and stress response through a multi-earthquake cycle history. We use a simple model configuration - an elastic subducting slab, an elastic upper plate (shallower than 40 km), and a visco-elastic upper plate (deeper than 40 km). This configuration leads to an upper plate that acts as a deforming elastic beam at inter-earthquake loading times and rates with a viscously relaxed regime at depths greater than 40 km. Analyses of our preliminary model results lead to the following: 1. Co-seismic stress transfer from the unloading elastic layer (shallow) into an elastically loading visco-elastic layer (deeper) - extends ~ 100 km inboard of locked zone. This stress transfer affects both coseismic and post-seismic surface displacements. 2. Post-seismic response of upper plate involves seaward motion for initial 10-20 years (~ 2 Maxwell times) after EQ. This occurs in spite of there being no slip on locked plate boundary - i.e. this is not plate boundary after-slip but rather is a consequence of stress relaxation in co-seismically loaded visco-elastic layer. However standard inversions of the surface displacement field would indicate significant after-slip along the locked plate interface. 3. By approximately 80 years (8 Maxwell times) system has returned to simple linear displacement pattern - the expected behavior for a shortening elastic beam. Prior to that time, the surface (observable) displacement pattern changes substantially over time and would result in an apparent temporal variation in coupling - from near-zero coupling to fully locked over ~ 80 years post-earthquake. These preliminary results indicate that care is needed in interpreting observed surface displacement fields from GPS, InSAR, etc. during the interseismic period. temporal variations in crustal deformation observed in regions such as the recent Tohoku, Maule, and Iquique megathrust events which are ascribed to fault plane after-slip may in fact reflect processes associated with re-equilibration of the visco-elastic subduction system.

Well sealing via thermite reactions

DOEpatents

Lowry, William Edward; Dunn, Sandra Dalvit

2016-11-15

A platform is formed in a well below a target plug zone by lowering a thermite reaction charge into the well and igniting it, whereby the products of the reaction are allowed to cool and expand to form a platform or support in the well. A main thermite reaction charge is placed above the platform and ignited to form a main sealing plug for the well. In some embodiments an upper plug is formed by igniting an upper thermite reaction charge above the main thermite reaction charge. The upper plug confines the products of ignition of the main thermite reaction charge.

CHARACTERIZATION OF SANDSTONE RESERVOIRS FOR ENHANCED OIL RECOVERY: THE PERMIAN UPPER MINNELUSA FORMATION, POWDER RIVER BASIN, WYOMING.

USGS Publications Warehouse

Schenk, C.J.; Schmoker, J.W.; Scheffler, J.M.

1986-01-01

Upper Minnelusa sandstones form a complex group of reservoirs because of variations in regional setting, sedimentology, and diagenetic alteration. Structural lineaments separate the reservoirs into northern and southern zones. Production in the north is from a single pay sand, and in the south from multi-pay sands due to differential erosion on top of the Upper Minnelusa. The intercalation of eolian dune, interdune, and sabkha sandstones with marine sandstones, carbonates, and anhydrites results in significant reservoir heterogeneity. Diagenetic alterations further enhance heterogeneity, because the degree of cementation and dissolution is partly facies-related.

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

Madaric, Juraj, E-mail: jurmad@hotmail.com; Klepanec, Andrej; Mistrik, Martin

Induction of therapeutic angiogenesis by autologous bone marrow mononuclear cell transplantation has been identified as a potential new option in patients with advanced lower-limb ischemia. There is little evidence of the benefit of intra-arterial cell application in upper-limb critical ischemia. We describe a patient with upper-extremity critical limb ischemia with digital gangrene resulting from hypothenar hammer syndrome successfully treated by intra-arterial autologous bone marrow mononuclear cell transplantation.

3D modeling of magnetotelluric data unraveling the tectonic setting and sources of magmatism in the northeastern corner of Borborema Province, NE Brazil

NASA Astrophysics Data System (ADS)

Padilha, A. L.; Vitorello, I.; Padua, M. B.; Batista, J. C.; Fuck, R. A.

2017-12-01

The Borborema Province in northeast Brazil is a complex orogenic system formed by crustal blocks of different ages, origin and evolution amalgamated during the West Gondwana convergence in late Neoproterozoic-early Phanerozoic Brasiliano Orogeny. We discuss here new magnetotelluric (MT) data collected along four linear profiles crisscrossing the northeastern corner of the province to assess its deep electrical resistivity structure. Dimensionality analysis showed that a 3D electrical structure predominates in the subsurface and thus the data were modeled by a 3D MT data inversion scheme. The modeling revealed several subvertical discontinuities, with significant lateral contrast in the overall geoelectric structure, down to upper mantle depths. A major conductivity anomaly is registered in the crust beneath Neoproterozoic supracrustal rocks (Serido Group) and this anomaly deepens to upper mantle depths in the northwest direction below a zone of Paleoproterozoic plutons (Caico Complex). It has been suggested that the Serido Group was originally initiated as a sedimentary basin developed upon a Paleoproterozoic basement during a Neoproterozoic extension event related to a collisional foredeep of a south-dipping subduction slab, contrary to our northwest-dipping conductivity vergence. In case of the Caico Complex, because of the petrogenesis of its orthogneisses that indicates partial melting of a metasomatically enriched spinel-to garnet-bearing lherzolite with adakitic features, we also propose a subduction zone environment for its original magmatism. Considering the tenuous evidence indicating that this conductive anomaly could extend down into the upper mantle in the same region where teleseismic tomography register an attenuation of P waves, it can be concluded that this zone could also be the source of the metasomatic fluids and minerals observed along north-south Mesozoic volcanic plugs and flows of alkaline rocks and alkali basalts (Macau-Queimadas belt). In contrast to the general pattern in several parts of the province exhibiting a multitude of resistive and conductive zones marking the crust and upper mantle, an elongated resistive cratonic-like keel in the WSW-ENE direction is observed along the southeastern side of the study area.

Subsurface images of the Eastern Rift, Africa, from the joint inversion of body waves, surface waves and gravity: investigating the role of fluids in early-stage continental rifting

NASA Astrophysics Data System (ADS)

Roecker, S.; Ebinger, C.; Tiberi, C.; Mulibo, G.; Ferdinand-Wambura, R.; Mtelela, K.; Kianji, G.; Muzuka, A.; Gautier, S.; Albaric, J.; Peyrat, S.

2017-08-01

The Eastern Rift System (ERS) of northern Tanzania and southern Kenya, where a cratonic lithosphere is in the early stages of rifting, offers an ideal venue for investigating the roles of magma and other fluids in such an environment. To illuminate these roles, we jointly invert arrival times of locally recorded P and S body waves, phase delays of ambient noise generated Rayleigh waves and Bouguer anomalies from gravity observations to generate a 3-D image of P and S wave speeds in the upper 25 km of the crust. While joint inversion of gravity and arrival times requires a relationship between density and wave speeds, the improvement in resolution obtained by the combination of these disparate data sets serves to further constrain models, and reduce uncertainties. The most significant features in the 3-D model are (1) P and S wave speeds that are 10-15 per cent lower beneath the rift zone than in the surrounding regions, (2) a relatively high wave speed tabular feature located along the western edge of the Natron and Manyara rifts, and (3) low (∼1.71) values of Vp/Vs throughout the upper crust, with the lowest ratios along the boundaries of the rift zones. The low P and S wave speeds at mid-crustal levels beneath the rift valley are an expected consequence of active volcanism, and the tabular, high-wave speed feature is interpreted to be an uplifted footwall at the western edge of the rift. Given the high levels of CO2 outgassing observed at the surface along border fault zones, and the sensitivity of Vp/Vs to pore-fluid compressibility, we infer that the low Vp/Vs values in and around the rift zone are caused by the volcanic plumbing in the upper crust being suffused by a gaseous CO2 froth on top of a deeper, crystalline mush. The repository for molten rock is likely located in the lower crust and upper mantle, where the Vp/Vs ratios are significantly higher.

A generalized public goods game with coupling of individual ability and project benefit

NASA Astrophysics Data System (ADS)

Zhong, Li-Xin; Xu, Wen-Juan; He, Yun-Xin; Zhong, Chen-Yang; Chen, Rong-Da; Qiu, Tian; Shi, Yong-Dong; Ren, Fei

2017-08-01

Facing a heavy task, any single person can only make a limited contribution and team cooperation is needed. As one enjoys the benefit of the public goods, the potential benefits of the project are not always maximized and may be partly wasted. By incorporating individual ability and project benefit into the original public goods game, we study the coupling effect of the four parameters, the upper limit of individual contribution, the upper limit of individual benefit, the needed project cost and the upper limit of project benefit on the evolution of cooperation. Coevolving with the individual-level group size preferences, an increase in the upper limit of individual benefit promotes cooperation while an increase in the upper limit of individual contribution inhibits cooperation. The coupling of the upper limit of individual contribution and the needed project cost determines the critical point of the upper limit of project benefit, where the equilibrium frequency of cooperators reaches its highest level. Above the critical point, an increase in the upper limit of project benefit inhibits cooperation. The evolution of cooperation is closely related to the preferred group-size distribution. A functional relation between the frequency of cooperators and the dominant group size is found.

Lateral traction of laminar flow between sliding pair with heterogeneous slip/no-slip surface

NASA Astrophysics Data System (ADS)

Wu, Zhenpeng; Zeng, Liangcai; Chen, Xiaolan; Chen, Keying; Ding, Xianzhong

2017-11-01

The problem of shaft axial motion which significantly affects the lubrication performance has been a common phenomenon in journal bearing systems. The existing work involved in the solution of shaft axial motion is also very rare. In this study, we choose to examine the flow between sliding pair in which regard we present a unique heterogeneous surface consisting of a slip zone and a no-slip zone. The results reveal the following points: 1) By appropriately arranging the slip zone to change the angle between the borderline and the moving direction of the upper plate, it is possible to control the direction of the lateral traction in which the liquid film acts on the upper plate. 2) Exponent of the power function of the borderline and aspect ratio of the computational domain are large or small are not conducive to increasing the effect of lateral traction. For the object of this study, the final results of the optimization are shown that the lateral traction can account for 20% of the resistance.

Kinematics of the New Madrid seismic zone, central United States, based on stepover models

USGS Publications Warehouse

Pratt, Thomas L.

2012-01-01

Seismicity in the New Madrid seismic zone (NMSZ) of the central United States is generally attributed to a stepover structure in which the Reelfoot thrust fault transfers slip between parallel strike-slip faults. However, some arms of the seismic zone do not fit this simple model. Comparison of the NMSZ with an analog sandbox model of a restraining stepover structure explains all of the arms of seismicity as only part of the extensive pattern of faults that characterizes stepover structures. Computer models show that the stepover structure may form because differences in the trends of lower crustal shearing and inherited upper crustal faults make a step between en echelon fault segments the easiest path for slip in the upper crust. The models predict that the modern seismicity occurs only on a subset of the faults in the New Madrid stepover structure, that only the southern part of the stepover structure ruptured in the A.D. 1811–1812 earthquakes, and that the stepover formed because the trends of older faults are not the same as the current direction of shearing.

The influence of cryogenic mass exchange on the distribution of viable microfauna in cryozems

NASA Astrophysics Data System (ADS)

Gubin, S. V.; Lupachev, A. V.; Shatilovich, A. V.; Myl'nikov, A. P.; Ryss, A. Yu.; Veremeeva, A. A.

2016-12-01

The role of cryogenic mass exchange in the distribution of the viable microfauna (ciliates, heterotrophic flagellates, and nematodes) in the profiles of cryoturbated cryogenic soils and in the upper layers of permafrost was revealed. The material for microbiological investigations was collected from the main horizons of cryozem profiles, including the zones with morphologically manifested processes of cryogenic mass exchange (the development of barren spots, cryoturbation, and suprapermafrost accumulation) and the zones affected by solifluction. The radiocarbon dating of the soil samples showed that the age of the organic cryogenic material and material buried in the course of solifluction varied from 2100 to 4500 years. Some zones with specific ecological conditions promoting the preservation of species diversity of the microfauna were found to develop in the cryozem profiles. A considerable part of the community (38% of ciliates, 58% of flagellates, and 50% of nematodes) maintained its viability in the dormant state, and in some cases, it could pass to the state of long-term cryobiosis in the upper layer of permafrost.

Midplate seismicity exterior to former rift-basins

USGS Publications Warehouse

Dewey, J.W.

1988-01-01

Midplate seismicity associated with some former rift-zones is distributed diffusely near, but exterior to, the rift basins. This "basin-exterior' seismicity cannot be attributed to reactivation of major basin-border faults on which uppercrustal extension was concentrated at the time of rifting, because the border faults dip beneath the basins. The seismicity may nonetheless represent reactivation of minor faults that were active at the time of rifting but that were located outside of the principal zones of upper-crustal extension; the occurrence of basin-exterior seismicity in some present-day rift-zones supports the existence of such minor basin-exterior faults. Other hypotheses for seismicity exterior to former rift-basins are that the seismicity reflects lobes of high stress due to lithospheric-bending that is centered on the axis of the rift, that the seismicity is localized on the exteriors of rift-basins by basin-interiors that are less deformable in the current epoch than the basin exteriors, and that seismicity is localized on the basin-exteriors by the concentration of tectonic stress in the highly elastic basin-exterior upper-crust. -from Author

Paleoecological evaluation of Late Eocene biostratigraphic zonations of the Pacific Coast of North America

USGS Publications Warehouse

McDougall, Kristin

1980-01-01

The late Eocene zonal criteria of the west coast of North America are to a large extent controlled by paleoecology and, therefore, the correlation of coeval but environmentally different benthic foraminiferal faunas cannot be achieved before paleoecological control of the biostratigraphy is understood. The faunal trends, morphology, characteristic occurrences and estimated upper depth limits of the benthic foraminifers and associated microfossils in the Oregon and Washington study sections lead to the recognition of paleoecologic facies. The interpretation of these late Eocene facies as bathymetric and low-oxygen facies is based on analogous late Eocene and Holocene assemblages. The paleoecologic facies criteria are often identical to the stage and zonal criteria. In the California zonal schemes, the Narizian zones are identified by lower and middle bathyal faunas whereas the Refugian zones are identified by outer neritic and upper bathyal faunas. The Washington late Eocene zones are identified by middle bathyal and transported neritic faunas. Modifications of the existing zonal schemes such that time and not paleoecology is the controlling factor results in a zonation that synthesizes the existing zonal schemes, recognizes regional stratigraphic ranges of diagnostic species, and removes paleoecologically controlled species occurrences. The late Narizian encompasses a bathyal and a neritic facies. The bathyal facies is correlative with a modified Bulimina corrugata Zone of California and the Uvigerina cf. U. yazooensis Zone of Washington. The neritic late Narizian facies corresponds to a modified Bulimina schencki-Plectofrondicularia cf. P. jenkinsi Zone of Washington and a modified Amphimorphina jenkinsi Zone of California. The Refugian can also be divided into a neritic and a bathyal facies. Although the early and late subdivisions of this stage are tentative, the early Refugian is equivalent to the modified versions of the Cibicides haydoni and the Uvigerina atwilli Subzones of the Valvulineria tumeyensis Zone and the Uvigerina vicksburgensis Zone (in part) of California and the modified version of the Sigmomorphina schencki Zone of Washington. The late Refugian is equivalent to modified versions of the California Uvigerina vicksburgensis Zone (in part) and the Washington Cassidulina galvinensis Zone. The Cibicides haydoni Subzone is the neritic facies of the Refugian Stage, whereas the faunas of the Uvigerina atwilli Subzone and the Uvigerina vicksburgensis, Sigmomorphina schencki and Cassidulina galvinensis Zones represent the bathyal Refugian facies.

Integrated Interdisciplinary Science of the Critical Zone as a Foundational Curriculum for Addressing Issues of Environmental Sustainability

ERIC Educational Resources Information Center

White, Timothy; Wymore, Adam; Dere, Ashlee; Hoffman, Adam; Washburne, James; Conklin, Martha

2017-01-01

Earth's critical zone (CZ) is the uppermost layer of Earth's continents, which supports ecosystems and humans alike. CZ science aims to understand how interactions among rock, soil, water, air, and terrestrial organisms influence Earth as a habitable system. Thus, CZ science provides the framework for a holistic-systems approach to teaching Earth…

White Historical Activity Theory: Toward a Critical Understanding of White Zones of Proximal Development

ERIC Educational Resources Information Center

Leonardo, Zeus; Manning, Logan

2017-01-01

Best known for arguing that individual development is part of social and historical development Vygotsky's entry into education may be captured by his concept of the "zone of proximal development" (ZPD). ZPD has not yet been synthesized with a critical study of whiteness. When ZPD is used to explain racial disparities in the service of…

Ordering Interfluves: a Simple Proposal for Understanding Critical Zone Evolution and Function

NASA Astrophysics Data System (ADS)

Brecheisen, Z. S.; Richter, D., Jr.; Moon, S.; Halpin, P. N.

2015-12-01

A geomorphic interfluve ordering system, a reciprocal to the Hortonian-Strahler stream network order, is envisioned at the Calhoun Critical Zone Observatory (CCZO) in the South Carolina Piedmont. In this system the narrowest and most highly dissected interfluves (gentle ridges and hilltops) are 1st order and increase in rank dendritically through interfluve branching and broadening. Interfluve order attends to the structure, function, and management of residual porous-solid systems in the transport of water, solutes, and eroded solids in our deeply weathered (>30m soil/saprolite) critical zone. Recently generated geospatial data regarding the interactions of geomorphology, human land use, and forest ecology further strengthen the utility of this system. These upland networks and corresponding "land-sheds" have potential in linking recent work in the fields of geophysics and geomorphology regarding bedrock weathering front dynamics. Patterns of bedrock weathering depth, landcover & land-use change, and soil erosion are considered as they correspond to interfluve order. With LiDAR mapping and the burgeoning development and utilization of geophysical techniques and models enabling new quantitative research of critical zone landscape structure and function, many physiographic regions could benefit from a system that delineates and orders interfluve networks.

Multiple antibiotic resistance patterns of rhizospheric bacteria isolated from Phragmites australis growing in constructed wetland for distillery effluent treatment.

PubMed

Chaturvedi, Sonal; Chandra, Ram; Rai, Vibhuti

2008-01-01

Susceptibility patterns of 12 different antibiotics were investigated against rhizospheric bacteria isolated from Phragmites australis from three different zones i.e. upper (0-5 cm), middle (5-10 cm), lower (10-15 cm) in constructed wetland system with and without distillery effluent. The major pollutants of distillery effluent were phenols, sulphide, heavy metals, and higher levels of biological oxygen demand (BOD), chemical oxygen demand (COD) etc. The antibiotic resistance properties of bacteria were correlated with the heavy metal tolerance (one of distillery pollutant). Twenty-two species from contaminated and seventeen species from non-contaminated site were tested by agar disc-diffusion method. The results revealed that more than 63% of total isolates were resistance towards one or more antibiotics tested from all the three different zones of contaminated sites. The multiple-drug resistance property was shown by total 8 isolates from effluent contaminated region out of which 3 isolates were from upper zone, 3 isolates from middle zone and 2 isolates were from lower zone. Results indicated that isolates from contaminated rhizosphere were found more resistant to antibiotics than isolates from non-contaminated rhizosphere. Further this study produces evidence suggesting that tolerance to antibiotics was acquired by isolates for the adaptation and detoxification of all the pollutants present in the effluent at contaminated site. This consequently facilitated the phytoremediation of effluent, which emerges the tolerance and increases resistance to antibiotics.

When interflow also percolates: downslope travel distances and hillslope process zones.

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

Jackson, C. Rhett; Bitew, Menberu; Du, Enhao

2014-02-17

In hillslopes with soils characterized by deep regoliths, such as Ultisols,Oxisols, and Alfisols, interflow occurs episodically over impeding layers near and parallel to the soil surface such as low-conductivity B horizons (e.g.Newman et al., 1998; Buttle andMcDonald, 2002; Du et al., In Review), till layers (McGlynn et al., 1999; Bishop et al., 2004), hardpans (McDaniel et al., 2008), C horizons (Detty and McGuire, 2010), and permeable bedrock (Tromp van Meerveld et al., 2007). As perched saturation develops within and above these impeding but permeable horizons, flow moves laterally downslope, but the perched water also continues to percolate through the impedingmore » horizon to the unsaturated soils and saprolite below. Perched water and solutes will eventually traverse the zone of perched saturation above the impeding horizon and then enter and percolate through the impeding horizon. In such flow situations, only lower hillslope segments with sufficient downslope travel distance will deliver water to the riparian zone within the time scale of a storm.farther up the slope, lateral flow within the zone of perched saturation. will act mainly to shift the point of percolation (location where a water packet leaves the downslope flow zone in the upper soil layer and enters the impeding layer) down the hillslope from the point of infiltration. In flatter parts of the hillslope or in areas with little contrast between the conductivities of the upper and impeding soil layers, lateral flow distances will be negligible.« less

The influence of four macrozoobenthic species on the abundance of the amphipod Corophium volutator on tidal flats of the Wadden Sea

NASA Astrophysics Data System (ADS)

Flach, E. C.

On the tidal flats of the Wadden Sea, a zonation pattern can be found with Corophium volutator and Nereis diversicolor as the dominating species of the upper intertidal zone and Arenicola marina and Cerastoderma edule as the dominating species of the lower zone. As C. volutator can live under a great variety of physical conditions, its restriction to higher areas might result from biotic interactions. This was investigated by field experiments on a tidal flat in the westernmost part of the Wadden Sea. Within large depopulated areas, small plots were recolonized with different densities of N. diversicolor, A. marina, C. edule and Macoma balthica and the subsequent settlement and dynamics of C. volutator were studied. In addition, A. marina and/or C. edule were added to or removed from small plots within a natural benthic community. Neither the presence of M. balthica not that of N. diversicolor significantly affected the abundance of C. volutator. A strongly negative effect was found of C. edule when present in high densities, whereas A. marina negatively affected C. volutator abundance already at relatively low densities. Local removals of A. marina and C. edule from their own zone resulted in increases of Corophium numbers at these locations and local additions of these species within the Corophium zone resulted in decreases of Corophium numbers at these locations. It is suggested that the major species to restrict C. volutator effectively to the upper tidal zone is A. marina.

Metagenomic analysis of nitrogen and methane cycling in the Arabian Sea oxygen minimum zone.

PubMed

Lüke, Claudia; Speth, Daan R; Kox, Martine A R; Villanueva, Laura; Jetten, Mike S M

2016-01-01

Oxygen minimum zones (OMZ) are areas in the global ocean where oxygen concentrations drop to below one percent. Low oxygen concentrations allow alternative respiration with nitrate and nitrite as electron acceptor to become prevalent in these areas, making them main contributors to oceanic nitrogen loss. The contribution of anammox and denitrification to nitrogen loss seems to vary in different OMZs. In the Arabian Sea, both processes were reported. Here, we performed a metagenomics study of the upper and core zone of the Arabian Sea OMZ, to provide a comprehensive overview of the genetic potential for nitrogen and methane cycling. We propose that aerobic ammonium oxidation is carried out by a diverse community of Thaumarchaeota in the upper zone of the OMZ, whereas a low diversity of Scalindua-like anammox bacteria contribute significantly to nitrogen loss in the core zone. Aerobic nitrite oxidation in the OMZ seems to be performed by Nitrospina spp. and a novel lineage of nitrite oxidizing organisms that is present in roughly equal abundance as Nitrospina. Dissimilatory nitrate reduction to ammonia (DNRA) can be carried out by yet unknown microorganisms harbouring a divergent nrfA gene. The metagenomes do not provide conclusive evidence for active methane cycling; however, a low abundance of novel alkane monooxygenase diversity was detected. Taken together, our approach confirmed the genomic potential for an active nitrogen cycle in the Arabian Sea and allowed detection of hitherto overlooked lineages of carbon and nitrogen cycle bacteria.

Metagenomic analysis of nitrogen and methane cycling in the Arabian Sea oxygen minimum zone

PubMed Central

Kox, Martine A.R.; Villanueva, Laura; Jetten, Mike S.M.

2016-01-01

Oxygen minimum zones (OMZ) are areas in the global ocean where oxygen concentrations drop to below one percent. Low oxygen concentrations allow alternative respiration with nitrate and nitrite as electron acceptor to become prevalent in these areas, making them main contributors to oceanic nitrogen loss. The contribution of anammox and denitrification to nitrogen loss seems to vary in different OMZs. In the Arabian Sea, both processes were reported. Here, we performed a metagenomics study of the upper and core zone of the Arabian Sea OMZ, to provide a comprehensive overview of the genetic potential for nitrogen and methane cycling. We propose that aerobic ammonium oxidation is carried out by a diverse community of Thaumarchaeota in the upper zone of the OMZ, whereas a low diversity of Scalindua-like anammox bacteria contribute significantly to nitrogen loss in the core zone. Aerobic nitrite oxidation in the OMZ seems to be performed by Nitrospina spp. and a novel lineage of nitrite oxidizing organisms that is present in roughly equal abundance as Nitrospina. Dissimilatory nitrate reduction to ammonia (DNRA) can be carried out by yet unknown microorganisms harbouring a divergent nrfA gene. The metagenomes do not provide conclusive evidence for active methane cycling; however, a low abundance of novel alkane monooxygenase diversity was detected. Taken together, our approach confirmed the genomic potential for an active nitrogen cycle in the Arabian Sea and allowed detection of hitherto overlooked lineages of carbon and nitrogen cycle bacteria. PMID:27077014

Insights upon upper crustal arhitecture of a subduction zone and its surroundings - Vrancea Zone and Focsani Basin - substantiated by geophysical studies

NASA Astrophysics Data System (ADS)

Bocin, A.; Stephenson, R.; Mocanu, V.

2007-12-01

The DACIA PLAN (Danube and Carpathian Integrated Action on Processes in the Lithosphere and Neotectonics) deep seismic reflection survey was performed in August-September 2001, with the proposed objective of obtaining new information on the deep structure of the external Carpathians nappes and the architecture of Tertiary/Quaternary basin developed within and adjacent to the Vrancea zone, including the rapidly subsiding Focsani Basin. The DACIA-PLAN profile is about 140 km long, having a roughly NW-SE direction, from near the southeast Transylvanian Basin, across the mountainous southeastern Carpathians and their foreland to near the Danube River. A high resolution 2.5D velocity model of the upper crust along the seismic profile has been determined from a tomographic inversion and a 2D ray tracing forward modelling of the DACIA PLAN first arrival data. Peculiar shallow high velocities indicate that pre-Tertiary basement in the Vrancea Zone (characterised by velocities greater than 5.6 km/s) is involved in Carpathian thrusting while rapid alternance, vertically or horizontally, of velocity together with narrowingly contemporary crustal events suggests uplifting. Further to the east, at the foreland basin-thrust belt transition zone (well defined within velocity values), the velocity model suggests a nose of the Miocene Subcarpathians nappe being underlain by Focsani Basin units. A Miocene and younger Focsani Basin sedimentary succession of ~10 km thickness is ascertained by a gradual increase of velocities and strongly defined velocity boundaries.

Generalized mathematical model of red muds’ thickener of alumina production

NASA Astrophysics Data System (ADS)

Fedorova, E. R.; Vinogradova, A. A.

2018-03-01

The article describes the principle of a generalized mathematical model of the red mud’s thickener construction. The model of the red muds’ thickener of alumina production consists of sub-models of flocculation zones containing solid fraction feed slurry, free-fall and cramped sedimentation zones or effective sedimentation zones, bleaching zones. The generalized mathematical model of thickener allows predicting the content of solid fraction in the condensed product and in the upper discharge. The sub-model of solid phase aggregation allows one to count up average size of floccules, which is created during the flocculation process in feedwell. The sub-model of the free-fall and cramped sedimentation zone allows one to count up the concentration profile taking into account the variable cross-sectional area of the thickener. The sub-model of the bleaching zone is constructed on the basis of the theory of the precipitation of Kinc, supplemented by correction factors.

Catalytic distillation process

DOEpatents

Smith, Jr., Lawrence A.

1982-01-01

A method for conducting chemical reactions and fractionation of the reaction mixture comprising feeding reactants to a distillation column reactor into a feed zone and concurrently contacting the reactants with a fixed bed catalytic packing to concurrently carry out the reaction and fractionate the reaction mixture. For example, a method for preparing methyl tertiary butyl ether in high purity from a mixed feed stream of isobutene and normal butene comprising feeding the mixed feed stream to a distillation column reactor into a feed zone at the lower end of a distillation reaction zone, and methanol into the upper end of said distillation reaction zone, which is packed with a properly supported cationic ion exchange resin, contacting the C.sub.4 feed and methanol with the catalytic distillation packing to react methanol and isobutene, and concurrently fractionating the ether from the column below the catalytic zone and removing normal butene overhead above the catalytic zone.

Catalytic distillation process

DOEpatents

Smith, L.A. Jr.

1982-06-22

A method is described for conducting chemical reactions and fractionation of the reaction mixture comprising feeding reactants to a distillation column reactor into a feed zone and concurrently contacting the reactants with a fixed bed catalytic packing to concurrently carry out the reaction and fractionate the reaction mixture. For example, a method for preparing methyl tertiary butyl ether in high purity from a mixed feed stream of isobutene and normal butene comprising feeding the mixed feed stream to a distillation column reactor into a feed zone at the lower end of a distillation reaction zone, and methanol into the upper end of said distillation reaction zone, which is packed with a properly supported cationic ion exchange resin, contacting the C[sub 4] feed and methanol with the catalytic distillation packing to react methanol and isobutene, and concurrently fractionating the ether from the column below the catalytic zone and removing normal butene overhead above the catalytic zone.

Geochemistry and origins of mineralized waters in the Floridan aquifer system, northeastern Florida

USGS Publications Warehouse

Phelps, G.G.

2001-01-01

Increases in chloride concentration have been observed in water from numerous wells tapping the Floridan aquifer system in northeastern Florida. Although most increases have been in the eastern part of Duval County, Florida, no spatial pattern in elevated chloride concentrations is discernible. Possible sources of the mineralized water include modern seawater intrusion; unflushed Miocene-to-Pleistocene-age seawater or connate water in aquifer sediments; or mineralized water from deeper zones of the aquifer system or from formations beneath the Floridan aquifer system. The purpose of this study was to document the chemical and isotopic characteristics of water samples from various aquifer zones, and from geochemical and hydrogeologic data, to infer the source of the increased mineralization. Water samples were collected from 53 wells in northeastern Florida during 1997-1999. Wells tapped various zones of the aquifer including: the Fernandina permeable zone (FPZ), the upper zone of the Lower Floridan aquifer (UZLF), the Upper Floridan aquifer (UFA), and both the UFA and the UZLF. Water samples were analyzed for major ions and trace constituents and for isotopes of carbon, oxygen, hydrogen, sulfur, strontium, chlorine, and boron. Samples of rock from the aquifer were analyzed for isotopes of oxygen, carbon, and strontium. In general, water from various aquifer zones cannot be differentiated based on chemistry, except for water from FPZ wells. Major-ion concentrations vary as much within the upper zone of the Lower Floridan aquifer and the Upper Floridan aquifer as between these two zones. Simple models of mixing between fresh ground water and either modern seawater or water from the FPZ as a mineralized end member show that many water samples from the UZLF aquifer and the UFA are enriched in bicarbonate, calcium, magnesium, sulfate, fluoride, and silica and are depleted in sodium and potassium (as compared to concentrations predicted by simple mixing). Chemical mass-balance models of mixing and reactions between a hypothetical initial seawater and aquifer minerals cannot account for the observed water chemistry in a few wells, implying a source other than seawater, either ancient or modern, or the occurrence of other more complex rock-water reactions. Hydrogeologic and geochemical data from water and aquifer samples indicate that the most likely source of mineralized water in some wells yielding water with increasing chloride concentrations is water from the FPZ. In other wells, the flushing of Miocene-to-Pleistocene-age seawater can account for the observed chloride concentrations. The fact that most of the water samples collected are a mixture of less than one percent of mineralized water with more than 99 percent fresh or recharge water makes identifying the source of the mineralized water difficult. Differences in carbon-14 and sulfur-34 values probably reflect areal differences in aquifer mineralogy and distribution of organic carbon related to paleokarst features. Geochemical mass-balance models of seawater-rock interaction are unable to account for the chemical and isotopic composition of mineralized water from the FPZ, which implies another source of mineralized water, such as a brine, or the occurrence of more complex water-rock reactions.

Carbon isotope chemostratigraphy and precise dating of middle Frasnian (lower Upper Devonian) Alamo Breccia, Nevada, USA

USGS Publications Warehouse

Morrow, J.R.; Sandberg, C.A.; Malkowski, K.; Joachimski, M.M.

2009-01-01

At Hancock Summit West, Nevada, western USA, uppermost Givetian (upper Middle Devonian) and lower and middle Frasnian (lower Upper Devonian) rocks of the lower Guilmette Formation include, in stratigraphic sequence, carbonate-platform facies of the conodont falsiovalis, transitans, and punctata Zones; the type Alamo Breccia Member of the middle punctata Zone; and slope facies of the punctata and hassi Zones. The catastrophically deposited Alamo Breccia and related phenomena record the ~ 382??Ma Alamo event, produced by a km-scale bolide impact into a marine setting seaward of an extensive carbonate platform fringing western North America. Re-evaluation of conodonts from the lower Guilmette Formation and Alamo Breccia Member, together with regional sedimentologic and conodont biofacies comparisons, now firmly locates the onset of the Johnson et al. (1985) transgressive-regressive (T-R) cycle IIc, which occurred after the start of the punctata Zone, within a parautochthonous megablock low in the Alamo Breccia. Whole-rock carbon isotope analyses through the lower Guilmette Formation and Alamo Breccia Member reveal two positive ??13Ccarb excursions: (1) a small, 3??? excursion, which is possibly correlative with the falsiovalis Event previously identified from sections in Western Europe and Australia, occurs below the breccia in the Upper falsiovalis Zone to early part of the transitans Zone; and (2) a large, multi-part excursion, dominated by a 6??? positive shift, begins above the start of the punctata Zone and onset of T-R cycle IIc and continues above the Alamo Breccia, ending near the punctata- hassi zonal boundary. This large excursion correlates with the punctata Event, a major positive ??13C excursion previously recognized in eastern Laurussia and northern Gondwana. Consistent with previous studies, at Hancock Summit West the punctata Event is apparently not associated with any regional extinctions or ecosystem reorganizations. In the study area, onset of the main punctata Event began after the start of both the punctata Zone and T-R cycle IIc, and preceded the Alamo impact by less than 650??k.y., as inferred from conodont biochronologic and regional rock-accumulation rate estimates. Although complicated by the heterolithic, high-energy deposits of the Alamo Breccia, the carbon isotope record of the breccia and post-breccia beds does not indicate a major impact-correlative perturbation to the carbon cycle. This study extends recognition of the punctata Event to western Laurussia, further reinforcing the potential global scale of the event and its potential importance to understanding early to middle Frasnian marine geochemistry and palaeoenvironments. Based on previous models and our observations, increased tectonic activity, increased nutrient flux to oceans, increased marine bioproductivity, widespread anoxia, and increased organic carbon burial were all likely key factors in driving the punctata Event excursion. Furthermore, periodic eustatic and regional relative sea-level rises may have played an important role in promoting organic carbon burial and in maintaining a link between the primary open-marine geochemical signal and that recorded on the shallow-marine, lower Guilmette carbonate platform. ?? 2009 Elsevier B.V. All rights reserved.

How Hives Collapse: Allee Effects, Ecological Resilience, and the Honey Bee

PubMed Central

Dennis, Brian; Kemp, William P.

2016-01-01

We construct a mathematical model to quantify the loss of resilience in collapsing honey bee colonies due to the presence of a strong Allee effect. In the model, recruitment and mortality of adult bees have substantial social components, with recruitment enhanced and mortality reduced by additional adult bee numbers. The result is an Allee effect, a net per-individual rate of hive increase that increases as a function of adult bee numbers. The Allee effect creates a critical minimum size in adult bee numbers, below which mortality is greater than recruitment, with ensuing loss of viability of the hive. Under ordinary and favorable environmental circumstances, the critical size is low, and hives remain large, sending off viably-sized swarms (naturally or through beekeeping management) when hive numbers approach an upper stable equilibrium size (carrying capacity). However, both the lower critical size and the upper stable size depend on many parameters related to demographic rates and their enhancement by bee sociality. Any environmental factors that increase mortality, decrease recruitment, or interfere with the social moderation of these rates has the effect of exacerbating the Allee effect by increasing the lower critical size and substantially decreasing the upper stable size. As well, the basin of attraction to the upper stable size, defined by the model potential function, becomes narrower and shallower, indicating the loss of resilience as the hive becomes subjected to increased risk of falling below the critical size. Environmental effects of greater severity can cause the two equilibria to merge and the basin of attraction to the upper stable size to disappear, resulting in collapse of the hive from any initial size. The model suggests that multiple proximate causes, among them pesticides, mites, pathogens, and climate change, working singly or in combinations, could trigger hive collapse. PMID:26910061

Use of fiber-optic DTS to investigate physical processes in thermohaline environments

NASA Astrophysics Data System (ADS)

Suarez, F. I.; Sarabia, A.; Silva, C.

2014-12-01

Salt-gradient solar ponds are artificial thermohaline environments that collect and store thermal energy for long time-periods. A solar pond consists of three distinctive zones: the upper convective zone, which is a thin layer of cooler, less salty water; the non-convective zone that has gradients in temperature and salinity; and the lower convective zone, a layer of high salinity brine where temperatures are the highest. The solar radiation that penetrates the upper layers of the pond reaches the lower convective zone and heats the high salinity brine, which does not rise beyond the lower convective zone because the effect of salinity on density is greater than the effect of temperature. The sediments beneath the pond are also heated due to the temperature increase in the lower convective zone, providing an additional volume for energy storage. To study the different physical processes occurring within a solar pond and its surroundings, we deployed a helicoidally wrapped distributed-temperature-sensing (DTS) system in a small-scale solar pond (1-m deep, 2.5-m long and 1.5-m width). In this installation, the pond is surrounded by a sandy soil that serves as an additional energy storage volume. The thermal profile is observed at a spatial sampling resolution of 1.1 cm (spatial resolution of 2.2. cm), a temporal resolution ranging from 15 s to 5 min, and a thermal resolution ranging from 0.05 to 0.5°C. These resolutions allow closing the energy balance and inferring physical processes such as double-diffusive convection, solar radiation absorption, and heat conduction through the sediments or through the non-convective zone. Independent thermal measurements are also being made to evaluate strengths and limitations of DTS systems in thermohaline environments, and to assess different calibration algorithms that have been proposed in the past.

Search for clues to Mesozoic graben on Long Island

USGS Publications Warehouse

Rogers, W.B.; Aparisi, M.; Sirkin, L.

1989-01-01

The position of Long Island between the Hartford Basin of Connecticut and graben structures reported from seismic reflection studies offshore to the south of the island suggests the possibility that other grabens associated with the early Mesozoic rifting might be buried beneath central Long Island. The hypothesis that post-rift tectonic activity would be related to the rift grabens and that such activity would be expressed in the post-rift sedimentary deposits led to a study of the Cretaceous and Pleistocene section to seek clues for buried grabens on Long Island. The Pleistocene glacial deposits in central and eastern Long Island have been mapped and a pollen zonation in the Upper Cretaceous section in the central part established. This work, combined with literature research, suggests the following: 1. (1) In central Long Island, the spacing of wells which reach basement enables a NE- striking zone free of basement samples to be defined where a buried graben could occur. This zone is referred to as the "permissible zone" because within it the data permit the existence of a hidden graben. 2. (2) The abrupt changes in the thickness of some pollen zones in the Upper Cretaceous deposits of central Long Island may be related to Cretaceous faulting. 3. (3) Buried preglacial valleys, the confluence of glacial lobes and major glacial outwash channels seem concentrated in west central and central Long Island. The loci of these drainage features may reflect structural control by a basement depression. 4. (4) The "permissible zone" is aligned with the zone of structures in an offshore zone south of central Long Island and with the Hartford Basin in Connecticut. Geophysical anomalies also fit into this pattern. 5. (5) A definitive answer to the question of a buried graben on Long Island will require a seismic line across the "permissible zone", or further drilling. ?? 1989.

The hydrogeology of Kilauea volcano

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

Ingebritsen, S.E.; Scholl, M.A.

1993-08-01

The hydrogeology of Kilauea volcano and adjacent areas has been studied since the turn of this century. However, most studies to date have focused on the relatively shallow, low-salinity parts of the ground-water system, and the deeper hydrothermal system remains poorly understood. The rift zones of adjacent Mauna Loa volcano bound the regional ground-water flow system that includes Kilauea, and the area bounded by the rift zones of Kilauea and the ocean may comprise a partly isolated subsystem. Rates of ground-water recharge vary greatly over the area, and discharge is difficult to measure, because streams are ephemeral and most ground-watermore » discharges diffusely at or below sea level. Hydrothermal systems exist at depth in Kilauea's east and southwest rift zone, as evidenced by thermal springs at the coast and wells in the lower east-rift zone. Available data suggest that dike-impounded, heated ground water occurs at relatively high elevations in the upper east- and southwest-rift zones of Kilauea, and that permeability at depth in the rift zones. Available data suggest that dike-impounded, heated ground water occurs at relatively high elevations in the upper east- and southwest-rift zones of Kilauea, and that permeability at depth in the rift zones (probably [le]10[sup [minus]15] m[sup 2]) is much lower than that of unaltered basalt flows closer to the surface ([ge]10[sup [minus]10] m[sup 2]). Substantial variations in permeability and the presence of magmatic heat sources influence that structure of the fresh water-salt water interface, so the Ghyben-Herzberg model will often fail to predict its position. Numerical modeling studies have considered only subsets of the hydrothermal system, because no existing computer code solves the coupled fluid-flow, heat- and solute-transport problem over the temperature and salinity range encountered at Kilauea. 73 refs., 7 figs., 2 tabs.« less

Isoprenoid quinones resolve the stratification of microbial redox processes in a biogeochemical continuum from the photic zone to deep anoxic sediments of the Black Sea.

PubMed

Becker, Kevin W; Elling, Felix J; Schröder, Jan M; Lipp, Julius S; Goldhammer, Tobias; Zabel, Matthias; Elvert, Marcus; Overmann, Jörg; Hinrichs, Kai-Uwe

2018-03-09

The stratified water column of the Black Sea serves as a model ecosystem for studying the interactions of microorganisms with major biogeochemical cycles. Here we provide detailed analysis of isoprenoid quinones to study microbial redox processes in the ocean. In a continuum from the photic zone through the chemocline into deep anoxic sediments of the southern Black Sea, diagnostic quinones and inorganic geochemical parameters indicate niche segregation between redox processes and corresponding shifts in microbial community composition. Quinones specific for oxygenic photosynthesis and aerobic respiration dominate oxic waters, while quinones associated with thaumarchaeal ammonia-oxidation and bacterial methanotrophy, respectively, dominate a narrow interval in suboxic waters. Quinone distributions indicate highest metabolic diversity within the anoxic zone, with anoxygenic photosynthesis being a major process in its photic layer. In the dark anoxic layer, quinone profiles indicate occurrence of bacterial sulfur and nitrogen cycling, archaeal methanogenesis, and archaeal methanotrophy. Multiple novel ubiquinone isomers, possibly originating from unidentified intra-aerobic anaerobes, occur in this zone. The respiration modes found in the anoxic zone continue into shallow subsurface sediments, but quinone abundances rapidly decrease within the upper 50 cm below sea floor, reflecting the transition to lower energy availability. In the deep subseafloor sediments, quinone distributions and geochemical profiles indicate archaeal methanogenesis/methanotrophy and potentially bacterial fermentative metabolisms. We observed that sedimentary quinone distributions track lithology, which supports prior hypotheses that deep biosphere community composition and metabolisms are determined by environmental conditions during sediment deposition. Importance Microorganisms play crucial roles in global biogeochemical cycles. Yet, we have only a fragmentary understanding of the diversity of microorganisms and their metabolisms, as the majority remains uncultured. Thus, culture-independent approaches are critical for determining microbial diversity and active metabolic processes. In order to resolve the stratification of microbial communities in the Black Sea, we comprehensively analyzed redox process-specific isoprenoid quinone biomarkers in a unique continuous record from the photic zone through the chemocline into anoxic subsurface sediments. We describe an unprecedented quinone diversity that allowed us to detect distinct biogeochemical processes including oxygenic photosynthesis, archaeal ammonia oxidation, aerobic methanotrophy and anoxygenic photosynthesis in defined geochemical zones. Copyright © 2018 American Society for Microbiology.

Prevention of upper gastrointestinal bleeding in critically ill Chinese patients: a randomized, double-blind study evaluating esomeprazole and cimetidine.

PubMed

Lou, Wenhui; Xia, Ying; Xiang, Peng; Zhang, Liangqing; Yu, Xiangyou; Lim, Sam; Xu, Mo; Zhao, Lina; Rydholm, Hans; Traxler, Barry; Qin, Xinyu

2018-04-20

To assess the efficacy and safety of esomeprazole in preventing upper gastrointestinal (GI) bleeding in critically ill Chinese patients, using cimetidine as an active comparator. A pre-specified non-inferiority limit (5%) was used to compare rates of significant upper GI bleeding in this randomized, double-blind, parallel-group, phase 3 study across 27 intensive care units in China. Secondary endpoints included safety and tolerability measures. Patients required mechanical ventilation and had at least one additional risk factor for stress ulcer bleeding. Patients were randomized to receive either active esomeprazole 40 mg, as a 30-min intravenous (IV) infusion twice daily, and an IV placebo cimetidine infusion or active cimetidine 50 mg/h, as a continuous infusion following an initial bolus of 300 mg, and placebo esomeprazole injections, given up to 14 days. Patients were blinded using this double-dummy technique. Of 274 patients, 2.7% with esomeprazole and 4.6% with cimetidine had significant upper GI bleeding (bright red blood in the gastric tube not clearing after lavage or persistent Gastroccult-positive "coffee grounds" material). Non-inferiority of esomeprazole to cimetidine was demonstrated. The safety profiles of both drugs were similar and as expected in critically ill patients. Esomeprazole is effective in preventing upper GI bleeding in critically ill Chinese patients, as demonstrated by the non-inferiority analysis using cimetidine as an active control. ClinicalTrials.gov identifier NCT02157376.

Thresholds in Soil Mineral Weathering and Relation to Streamwater Chemistry in Glaciated Catchments of the Northeastern USA

NASA Astrophysics Data System (ADS)

Bailey, S. W.; Ross, D. S.

2015-12-01

Primary mineral dissolution (i.e. weathering) is a critical process in forested catchments as an important consumer of acidity and CO2, the principle source of nutrients such as Ca, K, and P, as well as the source of toxic cations such as Al. Two common limitations of weathering studies are inadequate determination of mineralogic composition and insufficient sampling depth to determine location and advancement of weathering reactions. We determined mineral stocks through EPMA mapping of Al, Ca, Fe, P, and Si content of soil samples and development of an image analysis routine that assigned mineral composition based on the content of these five elements. Portions of the classified maps were confirmed by optical petrography and full elemental analysis by SEM-EDS. Samples were analyzed for soil profiles >2m depth (~1.5m past the upper boundary of the "unweathered" C horizon). Study sites spanned a range of weatherability found in catchments in glaciated northeastern USA including Winnisook, NY (sandstone parent material, 100 ppm Ca), Hubbard Brook, NH (granite, 0.9% Ca), and Sleepers River, VT (calcareous granulite, 3.5% Ca). All profiles exhibited a weathering front, or threshold above which the most reactive minerals (calcite, apatite) have been depleted. However, in all cases this threshold was below the rooting zone, and in many profiles, it was well below the C horizon interface. Catchment scale Ca exports reflect this deeper weathering source while rooting zone exchangeable Ca was highly variable, probably reflecting spatial patterns of hydrologic flowpaths which bring deeper weathering products to the surface only in certain landscape positions. These results suggest that nutrient cycling and critical loads models, which assume that ecologically relevant weathering is confined to the rooting zone, need to be refined to account for deeper weathering and spatial patterns of lateral and upward hydrologic fluxes. Similarly, recovery from cultural acidification may be limited in portions of catchments where hydrologic connections do not provide a vehicle for weathering products to recharge the biologically active portion of the subsurface.

Dinoflagellate cyst biostratigraphy of the Upper Cretaceous succession in the sub-Arctic region

NASA Astrophysics Data System (ADS)

Radmacher, Wiesława; Tyszka, Jarosław; Mangerud, Gunn; Pearce, Martin

2017-04-01

The study provides a solid basis for the first palynostratigraphic zonation of the Upper Cretaceous sub-Arctic succession. Dinoflagellate cysts from the unique composite section, combining samples from the shallow stratigraphic core 6711/4-U-1 and core-samples from well 6707/10-1 in the Norwegian Sea, were studied and compared to palynological data from the south-western Barents Sea, wells 7119/12-1, 7119/9-1, 7120/7-3, 7120/5-1 and 7121/5-1. Dinoflagellate cysts diagnostic for late Maastrichtian that are missing in the Barents Sea are recorded in both sections in the Norwegian Sea. This adds new valuable data from the time interval often represented by a significant regional hiatus in the area. Seven new and three previously recognised zones are identified, based on top and base occurrence of selected age diagnostic taxa. In addition, one Abundance Subzone is introduced. The biostratigraphic zonation includes: the intra late Albian to intra early Cenomanian Subtilisphaera kalaalliti Interval Zone sensu Nøhr-Hansen (1993); the intra early Cenomanian to intra late Cenomanian Palaeohystrichophora infusorioides-Palaeohystrichophora palaeoinfusa Interval Zone sensu Radmacher et al. (2014); the intra Turonian to ?intra early Coniacian Heterosphaeridium difficile Interval Zone sensu Nøhr-Hansen (2012); the ?intra early Coniacian to late Santonian Dinopterygium alatum Interval Zone sensu Radmacher et al. (2014); the ?early Campanian Palaeoglenodinium cretaceum Interval Zone sensu Radmacher et al. (2014); the intra Campanian Hystrichosphaeridium dowlingii-Heterosphaeridium spp. Interval Zone sensu Radmacher et al. (2015); the intra late Campanian Chatangiella bondarenkoi Interval Zone sensu Radmacher et al. (2014) encompassing the Heterosphaeridium bellii Abundance Subzone; the early Maastrichtian Cerodinium diebelii Interval Zone sensu Nøhr-Hansen (1996) and the intra late Maastrichtian Wodehouseia spinata Range Zone sensu Nøhr-Hansen (1996). The Heterosphaeridium bellii is a newly described species important for biostratigraphical and palaeoenvironmental interpretations. Comparison of the recorded dinoflagellate cyst events with the published data from adjacent areas, such as west and east Greenland, North Sea, offshore eastern Canada and northern Siberia allows for sub-Arctic interregional correlations. This research was partially supported by EEA Financial Mechanism and Norwegian Financial Mechanism and the Research Council of Norway.

Balancing the costs of mobility investments in work zones : phase 1 final report.

DOT National Transportation Integrated Search

2015-06-01

Work zone safety and mobility continue to be critical transportation concerns in Michigan and elsewhere. : Previous research has led to the development of a variety of tools, performance measures and decision-making frameworks to analyze work zone sa...

76 FR 48751 - Security Zones; Captain of the Port Lake Michigan Zone

Federal Register 2010, 2011, 2012, 2013, 2014

2011-08-09

...-AA87 Security Zones; Captain of the Port Lake Michigan Zone AGENCY: Coast Guard, DHS. ACTION: Notice of... in the Chicago area, the Captain of the Port Sector Lake Michigan has determined that to better... critical infrastructure in the Chicago area. Based on this review, the Captain of the Port Sector Lake...

The role of the hyporheic zone across stream networks

Treesearch

Steven M. Wondzell

2011-01-01

Many hyporheic papers state that the hyporheic zone is a critical component of stream ecosystems, and many of these papers focus on the biogeochemical effects of the hyporheic zone on stream solute loads. However, efforts to show such relationships have proven elusive, prompting several questions: Are the effects of the hyporheic zone on stream ecosystems so highly...

Modeling and analysis of elastic fields in tibia and fibula

NASA Astrophysics Data System (ADS)

Ghosh, M.; Chowdhury, B. U.; Parvej, M. S.; Afsar, A. M.

2017-12-01

In this study, stress analysis of tibia and fibula subjected to body weight in static condition was carried out. The tibia and fibula were fabricated by casting process. A 3-D solid model of tibia and fibula was developed in SolidWorks by using the geometry of cross sections at different locations of the fabricated tibia and fibula. The 3-D model was analyzed by ANSYS to evaluate the stress, strain, and deformation for identifying the critical sections of tibia and fibula. It is found that, in terms of deformation, the critical zone is the contact zone between tibia-fibula and patella. However, in terms of stress, the critical zone is located on fibula between 25% and 40% height from the lower mating portion of the tibia and fibula.

Experiment 2033. Injection Test of Upper EE-3 Fracture Zone

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

Grigsby, Charles O.

1983-09-12

This experiment is designed to investigate the apparent lithologic boundary between the low-opening-pressure fracture system (upper EE-3 fracture and Phase I system) and the high-opening-pressure fracture system (lower fracture in EE-3 and in EE-2). The experiment will test for resistence to breakthrough into the lower EE-2 fracture system at relatively low pressure and will define the veting behavior of the low pressure system.

Sedimentary record of relay zone evolution, Central Corinth Rift (Greece): Role of fault propagation and structural inheritance.

NASA Astrophysics Data System (ADS)

Hemelsdaël, Romain; Ford, Mary; Meyer, Nicolas

2013-04-01

Relay zones along rift border fault systems form topographic lows that are considered to allow the transfer of sediment from the footwall into hanging wall depocentres. Present knowledge focuses on the modifications of drainage patterns and sediment pathways across relay zones, however their vertical motion during growth and interaction of faults segments is not well documented. 3D models of fault growth and linkage are also under debate. The Corinth rift (Greece) is an ideal natural laboratory for the study of fault system evolution. Fault activity and rift depocentres migrated northward during Pliocene to Recent N-S extension. We report on the evolution of a relay zone in the currently active southern rift margin fault system from Pleistocene to present-day. The relay zone lies between the E-W East Helike (EHF) and Derveni faults (DF) that lie just offshore and around the town of Akrata. During its evolution the relay zone captured the antecedent Krathis river which continued to deposit Gilbert-type deltas across the relay zone during fault interaction, breaching and post linkage phases. Moreover our work underlines the role that pre-existing structure in the location of the transfer zone. Offshore fault geometry and kinematics, and sediment distribution were defined by interpretation and depth conversion of high resolution seismic profiles (from Maurice Ewing 2001 geophysical survey). Early lateral propagation of the EHF is recorded by synsedimentary fault propagation folds while the DF records tilted block geometries since initiation. Within the relay zone beds are gradually tilted toward the basin before breaching. These different styles of deformation highlight mechanical contrasts and upper crustal partition associated with the development of the Akrata relay zone. Onshore detailed lithostratigraphy, structure and geomorphological features record sedimentation across the subsiding relay ramp and subsequent footwall uplift after breaching. The area is characterised by the successive deposition of the northward prograding Platanos Gilbert-type delta (Middle group; deposited in hangingwall of the Pirgaki-Mamoussia fault) and the NE to E prograding Akrata Gilbert-type delta (Upper group). The Akrata Gilbert-type delta records progressive rotation and lengthening of the relay ramp as the East Helike fault and Derveni fault propagated laterally (from around 0.8 Ma) and started to overlap. The relay ramp was then breached by the Krathis fault (around 0.45 Ma) and the latter reactivated a NW-SE oriented inherited structure. Onshore-offshore correlation and profile restoration of the Upper group demonstrate the presence of this pre-existing structure (detachment fault?) below the Akrata relay zone that was responsible for significant eastward thickening in early rift sediments (Lower to Middle group). Our evolution model is consistent with the 'isolated fault' model where a fault array initially develops from growth of kinematically independent fault segments and fault displacement gradually accumulates during pre- and post-linkage stages. Despite the prominent control of pre-existing fabrics on the location of the transfer zone, lateral fault propagation and interaction can be well documented.