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1

Carbon and oxygen isotopes of Maastrichtian Danian shallow marine carbonates: Yacoraite Formation, northwestern Argentina  

NASA Astrophysics Data System (ADS)

The Maastrichtian-Danian limestones of the Yacoraite Formation (northwestern Argentina) show carbon and oxygen isotopic values consistent with shallow marine conditions. The members of the formation respond to different sedimentary environments and are characterised by distinctive stable isotopes and geochemistry. The basal Amblayo Member is composed of high-energy dolomitic limestones and limestones with positive isotopic values (+2‰ ? 13C, +2‰ ? 18O). The top of the member reveals an isotopic shift of ? 13C (-5‰) and ? 18O (-10‰), probably related to a descent in the sea level. The sandy Güemes Member has isotopically negative (-2‰ ? 13C, -1‰ ? 18O) limestones, principally controlled by water mixing, decreased organic productivity, and compositional changes in the carbonates. The isotopically lighter limestones are calcitic, with a greater terrigenous contribution and different geochemical composition (high Si-Mn-Fe-Na, low Ca-Mg-Sr). These isotopic and lithological changes relate to the Cretaceous-Palaeogene transition. The Alemanía Member, composed of dolomitic limestones and pelites, represents a return to marine conditions and shows a gradual increase in isotopic values, reaching values similar to those of the Amblayo Member. The Juramento Member, composed of stromatolite limestones, shows isotopic variations that can be correlated with the two well-defined, shallowing-upward sequences of the member.

Marquillas, Rosa; Sabino, Ignacio; Nobrega Sial, Alcides; Papa, Cecilia del; Ferreira, Valderez; Matthews, Stephen

2007-04-01

2

Hydrogeology of formation waters, northwestern Alberta basin  

SciTech Connect

Generally, temperature seems to be the main controlling factor on salinity distributions. The salinity of formation waters increases in the vicinity of evaporitic beds, and decreases close to the surface because of mixing with fresh meteoric water introduced through local flow systems. The Lower and Middle Devonian pre-Prairie aquifer systems, beneath the regionally extensive Prairie aquiclude, are characterized by regional topographically-driven flow updip to the northeast. The flow of formation waters in the northeastern Alberta played an important role in the formation of the huge Athabasca oil sands deposits. Hydrocarbons that migrated into the area from the west were trapped into local reservoirs, and biodegraded and washed by fresh meteoric water introduced by local flow systems. Environmentally, the subsurface hydrogeology in the area imposes specific constraints on waste disposal in deep formations mostly because of the absence of a thick, continuous regional aquitard and because most aquifers subcrop at shallow depth or crop out and discharge along the valleys of the Athabasca River system and at the basin edge.

Bachu, S.; Underschultz, J.R. (Alberta Geological Survey, Edmonton (Canada))

1993-10-01

3

Geological context, mineralization, and timing of the Juramento sediment-hosted stratiform copper-silver deposit, Salta district, northwestern Argentina  

NASA Astrophysics Data System (ADS)

The Juramento deposit in northwestern Argentina exhibits several readily visible general characteristics of sediment-hosted stratiform copper (SSC) mineralization. It consists of fine-grained disseminated base-metal sulfides within marine to lacustrine graybeds (the basal whitish Late Cretaceous Lecho Sandstone and shallow-water carbonates of the overlying Maastrichtian Yacoraite Formation) that overlie a thick sequence of redbeds (the Pirgua Subgroup). The property has been examined and drilled in three successive exploration programs as a possible analog of world-class mineralization in the copperbelts of central Africa and the Kupferschiefer. The present report provides specific field and laboratory results that confirm the classification as SSC-type mineralization. The host graybeds are the basal sandstone and overlying oolitic and stromatolitic units of the Yacoraite Formation, which are shown from textural studies to be carbonaceous and to have initially contained very fine-grained, disseminated, syndiagenetic pyrite. These sediments would have been sufficiently porous and permeable in early diagenetic time to allow an infiltration of metalliferous fluids from the underlying redbeds, resulting in the observed progressive replacement of in situ pyrite by common base-metal sulfides (sphalerite, galena, argentiferous tetrahedrite, and copper-rich sulfides: first chalcopyrite, then bornite, and finally chalcocite). Sulfur isotope analyses indicate that a portion of the sulfur of ore-stage sulfides is isotopically heavier than that of pyrite, possibly due to a contribution from associated gypsum. Ore-stage sulfides are zoned vertically and obliquely through the mineralized zones, from cupriferous sulfides at low stratigraphic levels to lead- and zinc-rich mineralization above, with unreplaced pyrite remaining within upper Yacoraite strata. The zoned sulfides and their replacement textures, the peneconformable configuration of the mineralized zones, and the position of ore-stage mineralization adjacent to a stratigraphically defined redox transition from redbeds upward into graybeds indicate an overprint of copper (and accompanying ore-stage metals) on originally pyritic graybeds. The influx of ore-stage metals, presumably in an oxidized low-temperature brine, terminated with a silicification event that effectively sealed the host carbonates. These observations and the overall genetic interpretation are consistent with the general deposit-scale genetic model for early diagenetic SSC mineralization. The regional geologic context is also consistent with its classification as a SSC deposit: It is hosted by post-oxyatmoversion sediments and was formed in association with evaporites at a low paleolatitude in a major intracontinental rift system.

Durieux, C. Gustavo; Brown, Alex C.

2007-11-01

4

Large-Scale Preconditioning of Deep-Water Formation in the Northwestern Mediterranean Sea  

Microsoft Academic Search

The large-scale processes preconditioning the winter deep-water formation in the northwestern Mediterranean Sea are investigated with a primitive equation numerical model where convection is parameterized by a non- penetrative convective adjustment algorithm. The ocean is forced by momentum and buoyancy fluxes that have the gross features of mean winter forcing found in the MEDOC area. The wind-driven barotropic circulation appears

Gurvan Madec; François Lott; Pascale Delecluse; Michel Crépon

1996-01-01

5

Simplified stratigraphic cross sections of the Eocene Green River Formation in the Piceance Basin, northwestern Colorado  

USGS Publications Warehouse

Thirteen stratigraphic cross sections of the Eocene Green River Formation in the Piceance Basin of northwestern Colorado are presented in this report. Originally published in a much larger and more detailed form by Self and others (2010), they are shown here in simplified, page-size versions that are easily accessed and used for presentation purposes. Modifications to the original versions include the elimination of the detailed lithologic columns and oil-yield histograms from Fischer assay data and the addition of ground-surface lines to give the depth of the various oil shale units shown on the cross section.

Dietrich, John D.; Johnson, Ronald C.

2013-01-01

6

Facies and Architecture of a Carboniferous Grounding-line System From the Guandacol Formation, Paganzo Basin, Northwestern Argentina  

Microsoft Academic Search

New outcrops of Middle Carboniferous glacigenic deposits found in the Guandacol Formation (western Paganzo Basin) are described in this paper. The study locality of Los Pozuelos Creek (northwestern Argentina) includes coarse-grained diamictites, rhythmites, laminated pebbly mudstones and shales that represent an expanded column of the Gondwanic glaciation in this region. Thirteen lithofacies recorded at the measured section have been grouped

S. A. Marenssi; A. Tripaldi; C. O. Limarino; A. T. Caselli

2005-01-01

7

Sedimentology and petroleum occurrence, Schoolhouse Member, Maroon Formation (Lower Permian), northwestern Colorado  

SciTech Connect

The Lower Permian Schoolhouse Member of the Maroon Formation (formerly considered the Schoolhouse Tongue of the Weber Sandstone) forms a partly exhumed petroleum reservoir in the Eagle basin of northwestern Colorado. The Schoolhouse consists mainly of yellowish gray to gray, low-angle to parallel bedded, very fine to fine-grained sandstone of eolian sand-sheet origin; interbedded fluvial deposits are present in most sections. The sand-sheet deposits of the Schoolhouse Member are sedimentologically and petrologically similar to those in the underlying red beds of the main body of the Maroon Formation, and the Schoolhouse is considered the uppermost sand sheet in the Maroon depositional sequence. The bleached and oil-stained Schoolhouse member is distinguished from the underlying Maroon red beds on the basis of its diagenetic history, which is related to regional hydrocarbon migration and development of secondary porosity. Geological and geochemical data suggest that Schoolhouse Member oils have upper Paleozoic sources, including the intrabasinal Belden Formation. 13 figs., 1 tab.

Johnson, S.Y.; Schenk, C.J.; Anders, D.L.; Tuttle, M.L. (Geological Survey, Denver, CO (USA))

1990-02-01

8

A new herrerasaurid (Dinosauria, Saurischia) from the Upper Triassic Ischigualasto Formation of northwestern Argentina.  

PubMed

Herrerasauridae comprises a basal clade of dinosaurs best known from the Upper Triassic of Argentina and Brazil, which have yielded remains of Herrerasaurus ischigualastensis and Staurikosaurus pricei, respectively. Systematic opinion regarding the position of Herrerasauridae at the base of Dinosauria has varied. Here we describe a new herrerasaurid, Sanjuansaurus gordilloi gen. n., sp. n., based on a partial skeleton from Carnian-age strata of the the Upper Triassic Ischigualasto Formation of northwestern Argentina. The new taxon is diagnosed by numerous features, including long, band-shaped and posterolaterally oriented transverse process on the posterior cervical vertebrae; neural spines of the sixth to eighth dorsal vertebrae, at least, bearing acute anterior and posterior processes; scapula and coracoid with everted lateral margins of the glenoid; and short pubis (63% of the femoral length). Phylogenetic analysis placed Sanjuansaurus within a monophyletic Herrerasauridae, at the base of Theropoda and including Herrerasaurus and Staurikosaurus. The presence of Sanjuansaurus at the base of the Ischigualasto Formation, along with other dinosaurs such as Herrerasaurus, Eoraptor, Panphagia, and Chromogisaurus suggests that saurischian dinosaurs in southwestern Pangea were already widely diversified by the late Carnian rather than increasing in diversity across the Carnian-Norian boundary. PMID:21594020

Alcober, Oscar A; Martinez, Ricardo N

2010-01-01

9

A new herrerasaurid (Dinosauria, Saurischia) from the Upper Triassic Ischigualasto Formation of northwestern Argentina  

PubMed Central

Abstract Herrerasauridae comprises a basal clade of dinosaurs best known from the Upper Triassic of Argentina and Brazil, which have yielded remains of Herrerasaurus ischigualastensis and Staurikosaurus pricei, respectively. Systematic opinion regarding the position of Herrerasauridae at the base of Dinosauria has varied. Here we describe a new herrerasaurid, Sanjuansaurus gordilloi gen. n., sp. n., based on a partial skeleton from Carnian-age strata of the the Upper Triassic Ischigualasto Formation of northwestern Argentina. The new taxon is diagnosed by numerous features, including long, band-shaped and posterolaterally oriented transverse process on the posterior cervical vertebrae; neural spines of the sixth to eighth dorsal vertebrae, at least, bearing acute anterior and posterior processes; scapula and coracoid with everted lateral margins of the glenoid; and short pubis (63% of the femoral length). Phylogenetic analysis placed Sanjuansaurus within a monophyletic Herrerasauridae, at the base of Theropoda and including Herrerasaurus and Staurikosaurus. The presence of Sanjuansaurus at the base of the Ischigualasto Formation, along with other dinosaurs such as Herrerasaurus, Eoraptor, Panphagia, and Chromogisaurus suggests that saurischian dinosaurs in southwestern Pangea were already widely diversified by the late Carnian rather than increasing in diversity across the Carnian-Norian boundary.

Alcober, Oscar A.; Martinez, Ricardo N.

2010-01-01

10

Deposition, diagenesis, and porosity development in Mississippian Castle Reef formation, northwestern Montana  

SciTech Connect

The Castle Reef formation forms the top of the Mississippian Madison Group in the Sawtooth Range of northwestern Montana and consists principally of dolograinstones, packstones, and wackestones that are disconformably overlain by Jurassic strata. The Caste Reef attains a maximum thickness of 145 m (476 ft) and can be subdivided into shoal, intershoal, shoal to open-platform, and open to restricted-platform facies representing an upward-shoaling sequence. Microprobe elemental analyses, cathodoluminescence and transmitted-light microscopy, and facies interpretation suggest primary intergranular porosities were destroyed soon after deposition by syntaxial overgrowths. Secondary moldic porosity with limpid equant and drusy cements developed along with destruction of primary porosity in the freshwater phreatic zone. Microprobe magnesium-calcium ratios of these cements and allochemical components range from 1:1.0 to 1:1.6, suggesting that mixing zone dolomitization occurred after cementation, probably by the Late Mississippian. Further cementation of porosity at depth after dolomitization was prohibited by hydrocarbon migration considered to be sourced from Devonian.

Harris, M.K.

1986-08-01

11

Geochemistry of the Dakota Formation of northwestern New Mexico: relevance to radioactive waste studies  

SciTech Connect

The Dakota Formation of the San Juan Basin in northwestern New Mexico consists predominantly of well-cemented sandstones and arenaceous mudstones. Clay mineral-rich rocks, derived from volcanic ash, are mapped as bentonites. The likely physical conditions during burial were temperatures between 35 to 60/sup 0/C and a pressure of about 0.5 kbar. X-ray studies reveal a mixture of montmorillonite, kaolinite, illite, and mixed layer clay minerals. The typical cation exchange capacities range from 20 to 40 meq/100 g for most samples. Radiometric age determinations of clay minerals by the K-Ar method yield 90 to 94 millions of years before present (MYBP) and Rb-Sr ages yield 93 + or - 8 MYBP. These dates agree with paleontological ages and indicate closed-system conditions for potassium, argon, rubidium, and strontium in these rocks. Closed-system conditions for cesium are inferred based on its greater retentivity than rubidium and potassium in clay-rich rocks. Neutron activation analysis (NAA) of the Dakota samples indicates normal lanthanide abundances and distribution in the bentonitic rocks; local lanthanide enrichment is noted where local uranium accumulations are noted. The uranium has been derived from several sources and fixed in the Dakota Formation at various times from roughly 60 to near 0.25 MYBP. The chalcophile elements copper, antimony, and lead are often fixed with uranium in organic-rich rocks and apparently have not migrated since fixation, even under oxidizing conditions. No mobilization for the lanthanides and barium is noted either. Collectively, the radiometric ages and NAA data indicate the bentonite and bentonite-sand mix to be suitable for overpack in radioactive waste repositories.

Brookins, D.G.

1982-12-01

12

Detrital Zircon Provenance of Neoproterozoic and Cambrian Neruokpuk Formation of northwestern Canada: Implications for Phanerozoic Arctic Evolution  

NASA Astrophysics Data System (ADS)

Neoproterozoic and Cambrian strata of northwestern Canada are characterized as being derived predominantly from one or more of three principal sources. The sources comprise cratonic rocks of Paleoproterozoic and Archean ages; early Neoproterozoic Mackenzie Mountains Supergroup clastic strata; and Mesoproterozoic Wernecke Supergroup clastic strata, which are widely preserved in the northern Canadian Cordillera. The Neruokpuk Formation is a Late Neoproterozoic and Early Cambrian turbiditic succession located adjacent to the Yukon Stable Block in northwestern Yukon and adjacent northeastern Alaska. The dominant lithology is quartz to quartz-lithic sandstone, locally containing altered detrital feldspar and muscovite indicating contributions from a metamorphic source. The unit forms part of a Neoproterozoic to Early Devonian slope and basin succession that can be correlated in detail to coeval strata in the Selwyn Basin of the northern Canadian Cordillera. However, the Devonian structural and magmatic record for the unit associates it more closely with the Arctic Alaska terrane to the west and to northern Ellesmere Island, some 2000 km to the northeast, than to its present position in northwestern Laurentia. To test whether the Neruokpuk Formation is autochthonous relative to northwestern Laurentia, samples of sandstone from both the Proterozoic lower part and the Cambrian upper part of the unit were processed for detrital zircon analyses. These results were compared to previously published results from the Cambrian of northwestern Canada, as well as to newly analysed Late Neoproterozoic and Cambrian control samples that are known to be autochthonous. Neruokpuk Formation zircons are dominated by 1800-2000 Ma grains with subsidiary populations of 1000-1600 Ma, 2300-2500 Ma and 2600-2900 Ma, consistent with a mixed provenance strongly dominated by a Laurentian cratonic source, with minor contributions from Mackenzie Mountains Supergroup (which is dominated by 1000-1700 Ma populations) and Wernecke Supergroup. In addition, detrital muscovite yielded disturbed Ar-Ar spectra of 1800-1900 Ma, consistent with the most dominant zircon population. Detrital zircon distributions dominated by north Laurentian cratonic populations are widespread along the Arctic margin as far afield as northeastern Greenland. After integrating stratigraphic, biostratigraphic, structural, petrographic and geochronologic data, we infer that the Neruokpuk Formation was most likely deposited more or less in its present location relative to the Laurentian craton. Thus the northeasternmost part of Arctic Alaska probably is not far-travelled. The same conclusion cannot be assumed for other parts of Arctic Alaska which may comprise several individual terranes, some of which may be far-travelled, that assembled prior to Late Devonian time.

Lane, L.; Gehrels, G. E.; Layer, P. W.

2012-12-01

13

Nahcolite Resources in the Green River Formation, Piceance Basin, Northwestern Colorado  

USGS Publications Warehouse

The U.S. Geological Survey (USGS) recently completed an assessment of in-place nahcolite (NaHCO3) resources in the Piceance Basin, northwestern Colorado. Nahcolite is present in the oil shale deposits of the Parachute Creek Member of the Eocene Green River Formation. It occurs as disseminated aggregates, nodules, bedded units of disseminated brown crystals, and white crystalline beds associated with dawsonite (NaAl(OH)2CO3) and halite (NaCl). The nahcolite-bearing facies are divided into an unleached part containing the nahcolite and halite, which is estimated to be as much as 1,130 ft thick, and an upper leached part several hundred feet thick containing minor nahcolite aggregates and nodules. Locally, thick beds of halite and brown fine-grained nahcolite lie in the depocenter of the basin, but thin laterally away from the basin center and grade into beds of white, coarse-grained nahcolite. In the central part of the study area, the top of the nahcolite-bearing rocks range in depth from about 1,300 to 2,000 ft. Dissolution of water-soluble minerals, mostly nahcolite and halite, in the upper part of the nahcolite-bearing facies has created a collapsed leached zone as much as 580 ft thick that consists of laterally continuous units of solution breccia and fractured oil shale containing solution cavities. The top of the leached zone is not yet defined in the basin, but it probably extends into the A groove in the upper part of the Parachute Creek Member.

Brownfield, Michael E.; Johnson, Ronald C.; Self, Jesse G.; Mercier, Tracey J.

2009-01-01

14

Quartz latite rheoignimbrite flows of the Etendeka Formation, north-western Namibia  

NASA Astrophysics Data System (ADS)

The Etendeka Formation of north-western Namibia consists of a sequence of interbedded quartz latites and tholeiitic basalts and forms part of the Karoo Igneous Province in southern Africa. The age of the Etendeka Formation is approximately 130 135 Ma. The quartz latites make up a significant proportion of the stratigraphic succession (<25% of the total stratigraphic thickness) and form as much as 60% of the outcrop area in the southern Etendeka. Apart from some systematic differences between pitchstones and devitrified quartz latite, largely explained by alteration processes, individual quartz latite units exhibit remarkably uniform compositions with no significant vertical or lateral variation. Geochemistry can be used as a primary criterion for the correlation of major quartz latite units over much of the southern Etendeka area enabling the reconstruction of the Etendeka Formation stratigraphy in this region. Individual quartz latite units occur as voluminous (400 2600 km3), widespread (up to 8800 km2), sheet-like deposits typically between 40 and 300 m thick. Each unit consists of basal, main and upper zones. The main zone generally constitutes over 70% of the thickness of the unit and typically consists of texturally featureless devitrified quartz latite. In contrast the basal and upper zones of the flow are characterised by flow banding, pitchstone lenses and breccia, with rare occurrences of pyroclastic textures. The quartz latites are sparsely porphyritic (<10% phenocrysts) with glassy or devitrified groundmass textures. The phenocrysts consist of plagioclase, pyroxene, titanomagnetite and rare ilmenite. Pyroxene geothermometry indicates high (1000 1100°C) temperatures of crystallisation which, coupled with the absence or primary hydrous phases, indicates that the quartz latites were relatively hot, H2O-undersaturated magmas. The quartz latites display features common to both rhyolite lavas and ignimbrites and are clearly the products of an unusual eruption style. The local preservation of pyroclastic textures and the broad areal extent of these units lead to the conclusion that the quartz latites are high-temperature rheomorphic ignimbrites (i.e. rheoignimbrites). A combination of high eruption temperature and relatively low viscosity helps to explain the often completely welded and homogeneous textures observed in most quartz latite outcrops in the Etendeka area.

Milner, Sc; Duncan, Ar; Ewart, A.

1992-02-01

15

Significance of the goniatite Bilinguites eliasi and associated biotas, Parkwood Formation and Bangor Limestone, northwestern Alabama ( USA).  

USGS Publications Warehouse

The Bangor Limestone contains conodonts, smaller calcareous foraminifers, and a sparse marine macrofauna dating it as late or latest Chesterian (Late Mississippian). The Parkwood Formation, a paralic sequence disconformably overlying the Bangor, has yielded a fauna containing the reticuloceratid ammonoid Bilinguites eliasi Manger and Saunders which permits correlation of the Parkwood Formation in north-western Alabama to the upper part of the Prairie Grove Member of the Hale Formation in the type Morrowan sequence. The macrofauna occurring with the ammonoid, supports this correlation. Bilinguites eliasi also alows correlation with the lower part of the Yeadonian Stage (lowest Namurian 'C') of Europe. Florules collected just below and above the goniatite occurrence in Frankling County correlate with those in the lower two-thirds of the New River Formation, southern West Virgina, and with the upper Namurian of western Europe. -from Authors

Henry, T. W.; Gordon, Jr, M.; Schweinfurth, S. P.; Gillespie, W. H.

1985-01-01

16

Four-toed theropod footprints and a paleomagnetic age from the Whetstone Falls Member of the Harebell Formation (Upper Cretaceous: Maastrichtian), northwestern Wyoming  

Microsoft Academic Search

The Harebell Formation is a syntectonic sequence of conglomeratic sediments deposited in a narrow, rapidly subsiding trough that formed in the latest Cretaceous along the eastern margin of the ancestral uplift of what are today the Teton and Gros Ventre Mountains of northwestern Wyoming. On at least two occasions subsidence temporarily exceeded the rate of sediment supply and the area

J. D. Harris; K. R. Johnson; J. Hicks; L. Tauxe

1996-01-01

17

Morphology and formation of spreading cracks on pillow lavas at Cape Grim, northwestern Tasmania, Australia  

NASA Astrophysics Data System (ADS)

Tertiary basaltic pillow lobes at Cape Grim, northwestern Tasmania, Australia display well-preserved spreading cracks in the glassy crust. The spreading cracks are lens-shaped or rectangular in plan view. In cross section, they consist of a graben-like depression with a broad floor bounded by steep scarps. The floor of spreading crack contains an axial crack and a number of ridges that are arranged symmetrically with respect to the axial crack. The ridges within spreading cracks are inferred to have formed by the regular, repeated production and splitting of new crust at the centre of the spreading crack. This new interpretation of ridges in spreading cracks differs from the previous interpretation in which they are regarded as elongate normal fault blocks. Our interpretation provides new insight into the propagation mechanisms of pillow lavas.

Goto, Yoshihiko; McPhie, Jocelyn

2012-09-01

18

Kizilcaören ore-bearing complex with carbonatites (northwestern Anatolia, Turkey): Formation time and mineralogy of rocks  

NASA Astrophysics Data System (ADS)

The results of isotope-geochronological and mineralogical studies of the rocks making up the Kizilcaören fluorite-barite-REE deposit, northwestern Anatolia, Turkey are discussed in the paper. The ore is a constituent of the subvolcanic complex localized in a large fault zone. The complex combines (from earlier to later rocks): (1) phonolite and trachyte stocks, (2) carbonatite and carbonate-silicate dikelike bodies; and (3) fluorite-barite-bastnaesite ore in the form of thick homogeneous veins and cement in breccia. The K-Ar dating of silicate igneous rocks and carbonatites shows that they were formed in the Chattian Age of the Oligocene 25-24 Ma ago. Mineralogical observations show that the ore is the youngest constituent in the rock complex. Supergene alteration deeply transformed ore-bearing rocks, in particular, resulting in leaching of primary minerals, presumably Ca-Mn-Fe carbonates, and in cementation of the residual bastnaesitefluorite framework by Fe and Mn hydroxides. Most of the studied rocks contain pyrochlore, LREE fluorocarbonates, Nb-bearing rutile, Fe-Mg micas, and K-feldspar. The genetic features of the deposit have been considered. In general, the ore-bearing rock complex is compared in the set of rocks and their mineralogy and geochemistry with deposits of the Gallinas Mountains in the United States, the Arshan and Khalyuta deposits in the western Transbaikalia region, and Mushugai-Khuduk deposit in Mongolia. The Kizilcaören deposit represents a variant of postmagmatic mineralization closely related to carbonatite magmatism associated with alkaline and subalkaline intermediate rocks.

Nikiforov, A. V.; Öztürk, H.; Altuncu, S.; Lebedev, V. A.

2014-02-01

19

Geological setting and paleomagnetism of the Eocene red beds of Laguna Brava Formation (Quebrada Santo Domingo, northwestern Argentina)  

NASA Astrophysics Data System (ADS)

The red bed succession cropping out in the Quebrada Santo Domingo in northwestern Argentina had been for long considered as Upper Triassic-Lower Jurassic in age based on weak radiometric and paleontological evidence. Preliminary paleomagnetic data confirmed the age and opened questions about the nature of fossil footprints with avian features discovered in the section. Recently the stratigraphic scheme was reviewed with the identification of previously unrecognized discontinuities, and a radiometric dating obtained in a tuff, indicated an Eocene age for the Laguna Brava Formation and the fossil bird footprints, much younger than the previously assigned. We present a detailed paleomagnetic study interpreted within a regional tectonic and stratigraphic framework, looking for an explanation for the misinterpretation of the preliminary paleomagnetic data. The characteristic remanent magnetizations pass a tilt test and a reversal test. The main magnetic carrier is interpreted to be low Ti titanomagnetites and to a lesser extent hematite. The characteristic remanent magnetization would be essentially detrital. The obtained paleomagnetic pole (PP) for the Laguna Brava Formation has the following geographic coordinates and statistical parameters: N = 29, Lon. = 184.5° E, Lat. = 75.0° S, A95 = 5.6° and K = 23.7. When this PP is compared with another one with similar age obtained in an undeformed area, a declination anomaly is recognized. This anomaly can be interpreted as Laguna Brava Formation belonging to a structural block that rotated about 16° clockwise along a vertical axis after about 34 Ma. This block rotation is consistent with the regional tectonic framework, and would have caused the fortuitous coincidence of the PP with Early Jurassic poles. According to the interpreted magnetostratigraphic correlation, the Laguna Brava Formation would have been deposited during the Late Eocene with a mean sedimentation rate of about 1.4 cm per thousand years, probably in relation to the onset of the Andean deformation.

Vizán, H.; Geuna, S.; Melchor, R.; Bellosi, E. S.; Lagorio, S. L.; Vásquez, C.; Japas, M. S.; Ré, G.; Do Campo, M.

2013-01-01

20

The geology and geochemistry of the Maru Banded Iron-Formation, northwestern Nigeria  

Microsoft Academic Search

Narrow units (< 1–30 m thick) of banded iron-formation (BIF) occur in the low-grade schist belt of the Maru district, northwest Nigeria. The schist belt consists of a deformed sequence of pelitic to semi-pelitic phyllites with subordinate iron-formation and quartiztes, and also amphibolites of inferred tholeiitic volcanic origin. The Maru BIF is commonly interlayered with phyllites within an antiformal fold.

J. A. Adekoya

1998-01-01

21

Tectonic control on the evolution of the fluvial systems of the Vinchina Formation (Miocene), northwestern Argentina  

Microsoft Academic Search

The Miocene Vinchina Formation accumulated in a large foreland basin is related to the uplift of the Andes Mountains. This 5100m thick unit was mostly deposited in fluvial environments, but short episodes of eolian and lacustrine sedimentation also occurred. Low-angle intraformational unconformities and dramatic facies changes define three depositional sequences. Sequence S1 is composed of sandstones and mudstones deposited in

C. Limarino; A. Tripaldi; S. Marenssi; L. Net; G. Re; A. Caselli

2001-01-01

22

A New Basal Sauropodomorph (Dinosauria: Saurischia) from Quebrada del Barro Formation (Marayes-El Carrizal Basin), Northwestern Argentina  

PubMed Central

Background Argentinean basal sauropodomorphs are known by several specimens from different basins; Ischigualasto, El Tranquilo, and Mogna. The Argentinean record is diverse and includes some of the most primitive known sauropodomorphs such as Panphagia and Chromogisaurus, as well as more derived forms, including several massospondylids. Until now, the Massospondylidae were the group of basal sauropodomorphs most widely spread around Pangea with a record in almost all continents, mostly from the southern hemisphere, including the only record from Antarctica. Methodology/Principal Finding We describe here a new basal sauropodomorph, Leyesaurus marayensis gen. et sp. nov., from the Quebrada del Barro Formation, an Upper Triassic-Lower Jurassic unit that crops out in northwestern Argentina. The new taxon is represented by a partial articulated skeleton that includes the skull, vertebral column, scapular and pelvic girdles, and hindlimb. Leyesaurus is diagnosed by a set of unique features, such as a sharply acute angle (50 degrees) formed by the ascending process of the maxilla and the alveolar margin, a straight ascending process of the maxilla with a longitudinal ridge on its lateral surface, noticeably bulging labial side of the maxillary teeth, greatly elongated cervical vertebrae, and proximal articular surface of metatarsal III that is shelf-like and medially deflected. Phylogenetic analysis recovers Leyesaurus as a basal sauropodomorph, sister taxon of Adeopapposaurus within the Massospondylidae. Moreover, the results suggest that massospondylids achieved a higher diversity than previously thought. Conclusions/Significance Our phylogenetic results differ with respect to previous analyses by rejecting the massospondylid affinities of some taxa from the northern hemisphere (e.g., Seitaad, Sarahsaurus). As a result, the new taxon Leyesaurus, coupled with other recent discoveries, suggests that the diversity of massospondylids in the southern hemisphere was higher than in other regions of Pangea. Finally, the close affinities of Leyesaurus with the Lower Jurassic Massospondylus suggest a younger age for the Quebrada del Barro Formation than previously postulated.

Apaldetti, Cecilia; Martinez, Ricardo N.; Alcober, Oscar A.; Pol, Diego

2011-01-01

23

Probable Ankylosaur Ossicles from the Middle Cenomanian Dunvegan Formation of Northwestern Alberta, Canada  

PubMed Central

A sample of six probable fragmentary ankylosaur ossicles, collected from Cenomanian deposits of the Dunvegan Formation along the Peace River, represent one of the first dinosaurian skeletal fossils reported from pre-Santonian deposits in Alberta. Specimens were identified as ankylosaur by means of a palaeohistological analysis. The primary tissue is composed of zonal interwoven structural fibre bundles with irregularly-shaped lacunae, unlike the elongate lacunae of the secondary lamellar bone. The locality represents the most northerly Cenomanian occurrence of ankylosaur skeletal remains. Further fieldwork in under-examined areas of the province carries potential for additional finds.

Burns, Michael E.; Vavrek, Matthew J.

2014-01-01

24

Permian upper Yates Formation carbonate/siliciclastic depositional patterns, northwestern shelf, Guadalupe Mountains, New Mexico  

SciTech Connect

Sedimentological field study of the upper three sandstones of the upper Yates Formation (Permian, Guadalupian), Guadalupe Mountains, New Mexico, has shed considerably light on the shelf depositional environment, morphologic profile, and temporal relationships of alternating carbonate and siliciclastic deposition. Primary sedimentary structures are rare, obscure, small scale (less than or equal to 20 cm; 8 in., height), and discontinuous. All structures indicate subaqueous deposition. From the sandstones nearest the Capitan, the shelfward progression of sedimentary structures indicates shelfward diminution of hydraulic energy. Evidence for a marginal mound shelf profile during sandstone deposition is inconclusive. All three sandstones continuously overlie the area of the marginal mound as inferred from the underlying carbonate facies, hence a marginal mound was not present or had no affect on transport of siliciclastics across the outer 5 km (3 mi) of the shelf. Each sandstone is characterized by a sharp, subplanar erosional base, and typically grades upward into peritidal carbonates, which exhibit along the shelf crest of the marginal mound one or more 1 to 2 m (3 to 6 ft) shoaling-upward hemicycles which commonly built up to depositional fill-level in response to episodic shelf subsidence of 1 to 2 m (3 to 6 ft). The sandstone intervals interbedded with shelf crest carbonate facies comprise sandstone/carbonate shoaling-upward hemicycles; contrary to current interpretation the sandstone represents the basal deeper water deposition, the carbonates represent the shoal water deposition.

Candelaria, M.P.

1983-03-01

25

Depositional environment of the Cambro-Ordovician Rose Run Formation in northeastern Ohio, and equivalent, Gatesburg Formation in northwestern Pennsylvania  

SciTech Connect

An ideal sedimentary sequence from the Rose Run Formation consists of three facies in the following order: (1) algal laminated/stromatolite facies, (2) bioturbated dolomite facies, and (3) crossbedded sandstone facies. The algal laminated/stromatolite facies is composed of fine to very fine crystalline dolomite with laminations 2-4 cm thick. Also observed in this facies are mudcracks. The bioturbated dolomite facies is a fine to medium crystalline dolomite with an average of 10% clastic constituents such as quartz, orthoclase, microcline, and glauconite. Bioturbation in this facies ranges from slight to well with burrows 0.5-3 cm in diameter. Other structures observed include rip-up clasts, pelloids, and oncolites. The cross-bedded sandstone facies is characterized by low-angle crossbedded, fine- to coarse-grained sandstones. This sandstone has on the average 79% quartz, 12% orthoclase, 6% microcline, 1% detridal chert, and 1-2% glauconite. The heavy mineral fraction consists of tourmaline and zircon in {approximately}1% concentrations. The grains are subrounded to rounded with a size range of 0.15-0.30 mm. Sedimentary structures include rip-up clasts, current ripples, herringbone crossbedding, and herringbone imbricate rip-up clasts.

Enterline, D.S.; Foos, A.M. (Univ. of Akron, OH (United States))

1991-03-01

26

The Inskip Formation, the Harmony Formation, and the Havallah Sequence of Northwestern Nevada - An Interrelated Paleozoic Assemblage in the Home of the Sonoma Orogeny  

USGS Publications Warehouse

An area between the towns of Winnemucca and Battle Mountain in northwestern Nevada, termed the arkosic triangle, includes the type areas of the middle to upper Paleozoic Inskip Formation and Havallah sequence, the Upper Devonian to Mississippian Harmony Formation, the Sonoma orogeny, and the Golconda thrust. According to an extensive body of scientific literature, the Havallah sequence, a diverse assemblage of oceanic rocks, was obducted onto the continent during the latest Permian or earliest Triassic Sonoma orogeny by way of the Golconda thrust. This has been the most commonly accepted theory for half a century, often cited but rarely challenged. The tectonic roles of the Inskip and Harmony Formations have remained uncertain, and they have never been fully integrated into the accepted theory. New, and newly interpreted, data are incompatible with the accepted theory and force comprehensive stratigraphic and tectonic concepts that include the Inskip and Harmony Formations as follows: middle to upper Paleozoic strata, including the Inskip, Harmony, and Havallah, form an interrelated assemblage that was deposited in a single basin on an autochthonous sequence of Cambrian, Ordovician, and lowest Silurian strata of the outer miogeocline. Sediments composing the Upper Devonian to Permian sequence entered the basin from both sides, arkosic sands, gravel, limestone olistoliths, and other detrital components entered from the west, and quartz, quartzite, chert, and other clasts from the east. Tectonic activity was expressed as: (1) Devonian uplift and erosion of part of the outer miogeocline; (2) Late Devonian depression of the same area, forming a trough, probably fault-bounded, in which the Inskip, Harmony, and Havallah were deposited; (3) production of intraformational and extrabasinal conglomerates derived from the basinal rocks; and (4) folding or tilting of the east side of the depositional basin in the Pennsylvanian. These middle to upper Paleozoic deposits were compressed in the Jurassic, causing east-verging thrusts in the eastern part of the depositional basin (Golconda thrust) and west-verging thrusts and folds in the western part. Hypotheses involving a far-traveled allochthon that was obducted from an ocean or back-arc basin are incompatible with modern observations and concepts.

Ketner, Keith B.

2008-01-01

27

The Kharapeh orogenic gold deposit: geological, structural, and geochemical controls on epizonal ore formation in West Azerbaijan Province, Northwestern Iran  

Microsoft Academic Search

The Kharapeh gold deposit is located along the northwestern margin of the Sanandaj–Sirjan Zone (SSZ) in the West Azerbaijan\\u000a province, Iran. It is an epizonal orogenic gold deposit formed within the deformed zone between central Iran and the Arabian\\u000a plate during the Cretaceous–Tertiary Zagros orogeny. The deposit area is underlain by Cretaceous schist and marble, as well\\u000a as altered andesite

Shojaeddin Niroomand; Richard J. Goldfarb; Farid Moore; Mohammad Mohajjel; Erin E. Marsh

2011-01-01

28

Isotopic dating of the Khoy metamorphic complex (KMC), northwestern Iran: A significant revision of the formation age and magma source  

Microsoft Academic Search

The Khoy metamorphic complex (KMC) consists of metabasite, metagranite and some metasediments, which are overlain by the Oligo-Miocene Qom formation. Because there are no reliable stratigraphic sequences or isotope dating data available, discordant ages for the formation and tectonic setting of the KMC have been proposed by many studies. For example, various studies have suggested a Jurassic age, Cretaceous age

Hossein Azizi; Sun-Lin Chung; Tsuyoshi Tanaka; Yoshihiro Asahara

2011-01-01

29

The Kharapeh orogenic gold deposit: Geological, structural, and geochemical controls on epizonal ore formation in West Azerbaijan Province, Northwestern Iran  

USGS Publications Warehouse

The Kharapeh gold deposit is located along the northwestern margin of the Sanandaj–Sirjan Zone (SSZ) in the West Azerbaijan province, Iran. It is an epizonal orogenic gold deposit formed within the deformed zone between central Iran and the Arabian plate during the Cretaceous–Tertiary Zagros orogeny. The deposit area is underlain by Cretaceous schist and marble, as well as altered andesite and dacite dikes. Structural analysis indicates that the rocks underwent tight to isoclinal recumbent folding and were subsequently co-axially refolded to upright open folds during a second deformation. Late- to post-tectonic Cenozoic granites and granodiorites occur northeast of the deposit area. Mineralization mainly is recognized within NW-trending extensional structures as veins and breccia zones. Normal faults, intermediate dikes, and quartz veins, oriented subparallel to the axial surface of the Kharapeh antiform, indicate synchronous extension perpendicular to the fold axis during the second folding event. The gold-bearing quartz veins are >1 km in length and average about 6 m in width; breccia zones are 10–50 m in length and ?1 m in width. Hydrothermal alteration mainly consists of silicification, sulfidation, chloritization, sericitization, and carbonatization. Paragenetic relationships indicate three distinct stages—replacement and silicification, brecciation and fracture filling, and cataclastic brecciation—with the latter two being gold-rich. Fluid inclusion data suggest mineral deposition at temperatures of at least 220–255°C and depths of at least 1.4–1.8 km, from a H2O–CO2±CH4 fluid of relatively high salinity (12–14 wt.% NaCl equiv.), which may reflect metamorphism of passive margin carbonate sequences. Ore fluid ?18O values between about 7? and 9? suggest no significant meteoric water input, despite gold deposition in a relatively shallow epizonal environment. Similarities to other deposits in the SSZ suggest that the deposit formed as part of a diachronous gold event during the middle to late Tertiary throughout the SSZ and during the final stages of the Zagros orogeny. The proximity of Kharapeh to the main tectonic suture of the orogen, well-developed regional fold systems with superimposed complex fracture geometries, and recognition of nearby volcanogenic massive sulfide systems that suggest a region characterized by sulfur- and metal-rich crustal rocks, collectively indicate an area of the SSZ with high favorability for undiscovered gold resources.

Niroomand, Shojaeddin; Goldfarb, Richard J.; Moore, Farib; Mohajjel, Mohammad; Marsh, Erin E.

2011-01-01

30

The Kharapeh orogenic gold deposit: geological, structural, and geochemical controls on epizonal ore formation in West Azerbaijan Province, Northwestern Iran  

NASA Astrophysics Data System (ADS)

The Kharapeh gold deposit is located along the northwestern margin of the Sanandaj-Sirjan Zone (SSZ) in the West Azerbaijan province, Iran. It is an epizonal orogenic gold deposit formed within the deformed zone between central Iran and the Arabian plate during the Cretaceous-Tertiary Zagros orogeny. The deposit area is underlain by Cretaceous schist and marble, as well as altered andesite and dacite dikes. Structural analysis indicates that the rocks underwent tight to isoclinal recumbent folding and were subsequently co-axially refolded to upright open folds during a second deformation. Late- to post-tectonic Cenozoic granites and granodiorites occur northeast of the deposit area. Mineralization mainly is recognized within NW-trending extensional structures as veins and breccia zones. Normal faults, intermediate dikes, and quartz veins, oriented subparallel to the axial surface of the Kharapeh antiform, indicate synchronous extension perpendicular to the fold axis during the second folding event. The gold-bearing quartz veins are >1 km in length and average about 6 m in width; breccia zones are 10-50 m in length and ?1 m in width. Hydrothermal alteration mainly consists of silicification, sulfidation, chloritization, sericitization, and carbonatization. Paragenetic relationships indicate three distinct stages—replacement and silicification, brecciation and fracture filling, and cataclastic brecciation—with the latter two being gold-rich. Fluid inclusion data suggest mineral deposition at temperatures of at least 220-255°C and depths of at least 1.4-1.8 km, from a H2O-CO2±CH4 fluid of relatively high salinity (12-14 wt.% NaCl equiv.), which may reflect metamorphism of passive margin carbonate sequences. Ore fluid ?18O values between about 7‰ and 9‰ suggest no significant meteoric water input, despite gold deposition in a relatively shallow epizonal environment. Similarities to other deposits in the SSZ suggest that the deposit formed as part of a diachronous gold event during the middle to late Tertiary throughout the SSZ and during the final stages of the Zagros orogeny. The proximity of Kharapeh to the main tectonic suture of the orogen, well-developed regional fold systems with superimposed complex fracture geometries, and recognition of nearby volcanogenic massive sulfide systems that suggest a region characterized by sulfur- and metal-rich crustal rocks, collectively indicate an area of the SSZ with high favorability for undiscovered gold resources.

Niroomand, Shojaeddin; Goldfarb, Richard J.; Moore, Farid; Mohajjel, Mohammad; Marsh, Erin E.

2011-04-01

31

Quaternary basin formation along the Dien Bien Phu fault zone and its neotectonic implication of northwestern Vietnam  

NASA Astrophysics Data System (ADS)

The Dien Bien Phu (DBP) fault zone is one of the most conspicuous fault systems in the Indochina, extending over a distance of 150 km from Yunnan, China through the NW Vietnam into Laos. Recent Global Positioning system (GPS) data in China yielded that the present clockwise rotation of the southeastern Tibet block geologically corresponds to a region of left-lateral strike-slip faults, such as the Xianshuihe-Xiaojang fault and Dien Bien Phu fault, which appear to have accommodated clockwise rotation; whereas other GPS data from the network of Southeast Asia proposed that Indochina constitutes a stable tectonic block moving approximately east with respect to Eurasia. Although above GPS data show insignificant differential motion along DBP fault, active sinistral slip can be identified by clear geomorphic features, focal solutions and seismicity distribution in a NNE-striking zone parallel to the fault zone. Mapping of surface fault traces along the DBP fault zone using field outcrops, geophysical data, and geomorphologic features recognized by the aerial photos, SRTM, ASTER imageries and derived digital elevation models shows that virtually all active faults are reactivated structures sub-parallel to chronostratigraphic boundary. Along the DBF fault, three larger basins have been developed by different kinematics from north to south. The northern one at Chan Nua is rhomboidal in shape with a dimension of 2.5 km?.5 km, which can be defined as a pull-apart basin resulted by the strike-slip motion of the DBP fault. The fault configuration associated with the central one changes to two parallel sinistral and sinistral-normal faults forming a narrow subsiding weak zone (10 km?.5 km) filled with Quaternary deposits. The southern one is, however, created by that the main DBP fault bends the strike from NNE to NE where branches out a sinistral- normal fault with N-striking controlling a half-graben basin (17 km? km) filled with Quaternary deposits about 200 m in depth above the late Neogene olivine basalt. The late Neogene basalt of age ca. 5 Ma seems being at least displaced 10 km by the branched sinistral-normal fault, giving a rate of ca. 2 mm/yr by left-lateral strike-slip since volcanic eruption. For the southern two basins, normal faulting has been confirmed occurring along their east margin, implying the NW-striking fault systems, i.e. Son La and Song Ma faults, in northwestern Vietnam are active. Although the proposed mechanisms of above-mentioned basins are still tentative, the DBP fault zone is undoubtedly undergoing extensional tectonic environment in rigid Indochina block. Further studies on basin depositional history and age determination are needed for the purpose of establishing the dynamic model of each basin and recognizing the neotectonic behavior of DBP fault.

Lai, K.; Chen, Y.; Chung, L.; Li, P.; Lam, D.

2006-12-01

32

Spatial and stratigraphic distribution of water in oil shale of the Green River Formation using Fischer assay, Piceance Basin, northwestern Colorado  

USGS Publications Warehouse

The spatial and stratigraphic distribution of water in oil shale of the Eocene Green River Formation in the Piceance Basin of northwestern Colorado was studied in detail using some 321,000 Fischer assay analyses in the U.S. Geological Survey oil-shale database. The oil-shale section was subdivided into 17 roughly time-stratigraphic intervals, and the distribution of water in each interval was assessed separately. This study was conducted in part to determine whether water produced during retorting of oil shale could provide a significant amount of the water needed for an oil-shale industry. Recent estimates of water requirements vary from 1 to 10 barrels of water per barrel of oil produced, depending on the type of retort process used. Sources of water in Green River oil shale include (1) free water within clay minerals; (2) water from the hydrated minerals nahcolite (NaHCO3), dawsonite (NaAl(OH)2CO3), and analcime (NaAlSi2O6.H20); and (3) minor water produced from the breakdown of organic matter in oil shale during retorting. The amounts represented by each of these sources vary both stratigraphically and areally within the basin. Clay is the most important source of water in the lower part of the oil-shale interval and in many basin-margin areas. Nahcolite and dawsonite are the dominant sources of water in the oil-shale and saline-mineral depocenter, and analcime is important in the upper part of the formation. Organic matter does not appear to be a major source of water. The ratio of water to oil generated with retorting is significantly less than 1:1 for most areas of the basin and for most stratigraphic intervals; thus water within oil shale can provide only a fraction of the water needed for an oil-shale industry.

Johnson, Ronald C.; Mercier, Tracey J.; Brownfield, Michael E.

2014-01-01

33

Spatial and stratigraphic distribution of water in oil shale of the Green River Formation using Fischer Assay, Piceance Basin, northwestern Colorado  

USGS Publications Warehouse

The spatial and stratigraphic distribution of water in oil shale of the Eocene Green River Formation in the Piceance Basin of northwestern Colorado was studied in detail using some 321,000 Fischer assay analyses in the U.S. Geological Survey oil-shale database. The oil-shale section was subdivided into 17 roughly time-stratigraphic intervals, and the distribution of water in each interval was assessed separately. This study was conducted in part to determine whether water produced during retorting of oil shale could provide a significant amount of the water needed for an oil-shale industry. Recent estimates of water requirements vary from 1 to 10 barrels of water per barrel of oil produced, depending on the type of retort process used. Sources of water in Green River oil shale include (1) free water within clay minerals; (2) water from the hydrated minerals nahcolite (NaHCO3), dawsonite (NaAl(OH)2CO3), and analcime (NaAlSi2O6.H20); and (3) minor water produced from the breakdown of organic matter in oil shale during retorting. The amounts represented by each of these sources vary both stratigraphically and areally within the basin. Clay is the most important source of water in the lower part of the oil-shale interval and in many basin-margin areas. Nahcolite and dawsonite are the dominant sources of water in the oil-shale and saline-mineral depocenter, and analcime is important in the upper part of the formation. Organic matter does not appear to be a major source of water. The ratio of water to oil generated with retorting is significantly less than 1:1 for most areas of the basin and for most stratigraphic intervals; thus water within oil shale can provide only a fraction of the water needed for an oil-shale industry.

Johnson, Ronald C.; Mercier, Tracey J.; Brownfield, Michael E.

2014-01-01

34

3D slicing of radiogenic heat production in Bahariya Formation, Tut oil field, North-Western Desert, Egypt.  

PubMed

A 3D block of radiogenic heat production was constructed from the subsurface total gamma ray logs of Bahariya Formation, Western Desert, Egypt. The studied rocks possess a range of radiogenic heat production varying from 0.21 ?Wm(-3) to 2.2 ?Wm(-3). Sandstone rocks of Bahariya Formation have higher radiogenic heat production than the average for crustal sedimentary rocks. The high values of density log of Bahariya Formation indicate the presence of iron oxides which contribute the uranium radioactive ores that increase the radiogenic heat production of these rocks. The average radiogenic heat production produced from the study area is calculated as 6.3 kW. The histogram and cumulative frequency analyses illustrate that the range from 0.8 to 1.2 ?Wm(-3) is about 45.3% of radiogenic heat production values. The 3D slicing of the reservoir shows that the southeastern and northeastern parts of the study area have higher radiogenic heat production than other parts. PMID:23291561

Al-Alfy, I M; Nabih, M A

2013-03-01

35

Stratigraphy, coal occurrence, and depositional history of the Paleocene Fort Union Formation, Sand Wash basin, northwestern Colorado  

SciTech Connect

The Fort Union Formation in the Sand Wash basin is divided into the massive Cretaceous and Tertiary (K/T) sandstone unit, lower coal-bearing unit, gray-green mudstone unit, basin sandy unit, and upper shaly unit. Lithofacies and coal-occurrence maps of the stratigraphic units indicate that sandstone bodies and coal beds occur along south-north oriented, intermontane fluvial systems. Net-sandstone-thickness trends of the massive K/T sandstone unit reveal laterally extensive channel-fill sandstones formed in north-flowing fluvial systems. The massive K/T sandstone unit's dominant source was in the Sawatch Range. Sandstones within the lower coal-bearing unit consist of similar north-flowing fluvial systems, but they are laterally discontinuous and have several tectonically active source areas, including the Uinta and Sierra Madre-Park uplifts, and Sawatch Range. Coal-occurrence maps of the lower coal-bearing unit indicate that maximum coal-bed thicknesses are greatest along the south-north-oriented fluvial axes. Coal beds thin and split to the east and west, confirming a direct relation between the position of thick, fluvial-sandstone bodies, which form a stable platform for peat accumulation, and the location of the thick coal beds. Above the lower coal-bearing unit, the gray-green mudstone unit forms north-trending belts centered R91W and R100W. The gray-green mudstone thins to the north and into the basin center and probably is lacustrine in origin, reflecting tectonic quiescence and cessation of coarse clastic sedimentation. The basin sandy unit is best developed in the central parts of the basin, where its fluvial depositional axis is oriented south-north. The upper shaly unit directly overlies the basin sandy unit and includes a thin Cherokee coal zone. The upper shaly unit has variable thicknesses due to erosion at the base of the Wasatch Formation and lateral facies changes.

Tyler, R. (Univ. of Texas, Austin, TX (United States))

1993-08-01

36

The oleaginous Botryococcus from the Triassic Yanchang Formation in Ordos Basin, Northwestern China: Morphology and its paleoenvironmental significance  

NASA Astrophysics Data System (ADS)

High abundance but rather low diversity algal fossils were found in the hydrocarbon source rocks of the Ch 7-2-Ch 7-3 section, Triassic Yanchang Formation in the Xifeng area of southwest Ordos Basin, which are mainly composed of prolific Leiosphaeridia and Botryococcus. Botryococcus colonies are of various forms; the majority is nubbly, with some of cluster and cotton shape. The nubbly colonies appear globular, cordiform, ternate petal, obtuse triangle, chrysanthemum shape and so on. Most Botryococcus are saffron or brown and are frequently covered with clay under transmission microscope, and shows strong yellow and light brown under fluorescence microscope. Botryococcus could live in freshwater and brackish water. The Botryococcus colonies that lived in fresh water are small with small single cells arranged radially, with undulant or indented edges. The Botryococcus colonies that lived in brackish water are bigger, with larger single cells arranged irregularly, with slippery contours. The most of Botryococcus are discovered from the organic-rich argillaceous sediment with abundant pyrites in the semi- and deep-lake facies, and shows they were preserved in low-energy reducing environments. Taphonomic characteristics of various microfossils and the present of Pediastrum in the phytoplankton flora indicate that they are in situ or near burial. The lake area of the Ordos Basin was gradually expanding and reaching its most extensive flood surface in the Ch 7 of Yanchang Formation interval during the Middle and Late Triassic, with warm climate, plentiful rainfall, and luxuriant vegetation, as determined by the environmental analysis with Botryococcus in Xifeng area. The presence of two ecological types of Botryococcus indicates that the salinity of lake water was fluctuating in the Ch 7 interval. The occurrence of symbiotic acritarchs and geochemical salinity indices show that the Ordos Lake was a typical fresh-water lake, which was gradually desalted, and its salinity fluctuation was narrow during the Mid-Later Triassic. The ecological type of the palynological flora discovered from the Ch 7 to Ch 8 in Xifeng area is similar to that from the Fuxian Lake, with abundant Botryococcus in the Yungui Plateau of China. These findings imply that the Ordos Basin was in a lower-latitude area of temperate to subtropical climate during the Middle and Late Triassic.

Ji, Li-ming; Yan, Kui; Meng, Fan-wei; Zhao, Min

2010-05-01

37

Monitoring of Intense Events of Deep Water Formations in the Northwestern Mediterranean over the last five years  

NASA Astrophysics Data System (ADS)

A multi-platforms and integrated monitoring system in the framework of the Mediterranean Ocean Observing System on Environment (MOOSE) enables to monitor the deep water formation processes. Since 2007, it provides high frequency in-situ temperature, salinity vertical profiles, derived from CTD measurements on moorings, ships, and gliders, as well as horizontal and vertical currents from moorings. The aim of this study is to investigate the temporal scales associated to the deep convection phases. We also studied the interannual variability of the deep convection and its implication in the evolution of deep water thermohaline characteristics. Recent measurements from the mooring lines reveal the temporal evolution of the physical processes interfering in the phases of deep convection. Horizontal currents were strongly equivalent barotropic during each deployment and strong currents were also recorded during the different events of deep ocean convection: high frequencies vertical velocities exceeded 10 cm.s-1 during the violent vertical mixing phase and strong mesoscale horizontal currents reached 40cm.s-1 during the spreading/restratification phase. Using a eddy-detection method based on a kinematic model, more than 34 eddies crossing the mooring line were detected between November 2009 and July 2012, 19 cyclones and 15 anticyclones. The radii (resp. velocities) ranging from 1.9 km to 20.0 km (resp. 2.5 cm.s?1 to 25.1 cm.s?1 ). The main mode of the distribution of eddies radii is centered at 4km for the cyclones and 5km for the anticyclones. The apparition of newly-formed deep waters was detected in winter 2009, 2010, 2011 and 2012. In winter 2010, two newly-formed deep waters were detected after the deep convection event, both present a different potential temperature but a similar salinity, suggesting that both might be formed in the cyclonic gyre, but in different locations. In 2012, two new deep waters were detected at the mooring location, one was identified as a result of open-ocean deep convection, while the other seems to be the result of a dense shelf water cascading event that occurred in winter 2012.

Houpert, Loïc; Durrieu de Madron, Xavier; Testor, Pierre; Bosse, Anthony; Mortier, Laurent

2014-05-01

38

Exploration strategy in Keg River carbonates of northwestern Alberta, Canada  

Microsoft Academic Search

The analysis of reservoir quality and seal capacity of the Middle Devonian Keg River carbonate reservoirs in northwestern Alberta requires facies studies of rock units of the Keg River Formation and of the overlying Muskeg and Sulphur Point formations. Using lithologic criteria, faunal type, and stratigraphic positions, the entire sequence is subdivided into ten major facies. The system used is

Majid

1987-01-01

39

From andesitic volcanism to the formation of a porphyry Cu-Au mineralizing magma chamber: the Farallón Negro Volcanic Complex, northwestern Argentina  

NASA Astrophysics Data System (ADS)

The geological relations and geochemical composition of extrusive and subvolcanic intrusive rocks of the Upper Miocene Farallón Negro Volcanic Complex (NW Argentina) were studied to reconstruct the evolution of a deeply eroded andesitic volcano over most its life history of some 3.5 my. This paper is part of an integrated study of the processes that generate magmatic-hydrothermal fluids responsible for the formation of porphyry-Cu-Au deposits. Here we present new data on bulk rock chemical and Nd, Sr and Pb isotopic compositions of unaltered volcanic and subvolcanic intrusive rocks, for which geological relations and ages are constrained by field-based stratigraphy and extensive Ar-Ar geochronology. The combined results indicate that voluminous volcanism started at ca. 9.7 Ma with the eruption of basaltic andesite to andesite lava flows and pyroclastic deposits. This basic to intermediate volcanism persisted until 7.5 Ma and was followed at 7.35 Ma by the eruption of dacites as the last recorded major extrusive event. The oldest andesitic intrusions, emplaced at 9.0 Ma, were followed by hypabyssal intrusions of basaltic andesite, andesite and dacite composition, which intruded the volcanic sequence between 8.3 and 6.1 Ma. Intrusions at 6.8±0.2 Ma led to the formation of over 800 Mt of porphyry-Cu-Au ore at Bajo de la Alumbrera. It was formed by a large flux of magmatic-hydrothermal fluids channeled through several phases of fractured dacitic porphyry, which together with immediately following barren andesitic intrusions make up a composite stock. After this magmatic-hydrothermal event, only minor rhyodacitic to rhyolitic intrusions were emplaced until magmatic activity ceased at 6.1 Ma. Geochemical data for the magmatic rocks indicate that the evolution of the system was dominated by mixing of a mafic magma with a felsic magma that contained a component of crustal material, as indicated by linear compositional correlations between compatible and incompatible elements. Initial strontium isotopic ratios vary between 0.7047 and 0.7118 while 143Nd/ 144Nd range from 0.5127 to 0.5124, and both isotopic variations correlate with each other and with SiO 2 content of the rocks. After 8.5 Ma, a continuous increase in the silica content of intrusive rocks suggests the gradual formation of a magma chamber. A substantial magma reservoir (>7 km 3) must have been established by the time of porphyry-Cu-Au mineralization, to allow rapid release of a large volume of ore-forming magmatic brine as a result of wholesale crystallization and de-volatilization of the magma chamber.

Halter, Werner E.; Bain, Nicolas; Becker, Katja; Heinrich, Christoph A.; Landtwing, Marianne; VonQuadt, Albrecht; Clark, Alan H.; Sasso, Anne M.; Bissig, Thomas; Tosdal, Richard M.

2004-08-01

40

Northwestern African Continental Shelf Sediments.  

National Technical Information Service (NTIS)

An investigation of the gravel, sand, silt, and clay components and carbonate content of the bottom surface sediments on the northwestern African shelf and upper slope reveals that sand, composed of biogenic material, quartz, and glauconite, is the most c...

R. L. McMaster T. P. Lachance

1968-01-01

41

Uranium Geochemical Exploration in Northwestern Luzon.  

National Technical Information Service (NTIS)

A reconnaissance geochemical stream water and sediment survey which was conducted in northwestern Luzon was able to detect ten uranium anomalous areas. These anomalous areas are located along a north-south trending zone of Miocene marine clastics and sedi...

G. Santos L. Fernandez M. Ogena G. Tauli

1980-01-01

42

Scholarship, Policy, and Personal Development at Northwestern.  

ERIC Educational Resources Information Center

Describes the author's experiences in the evaluation training program at Northwestern University (1978-1980) in a postdoctoral fellowship in methodology and evaluation research. Also discusses the value of the friendships and professional relationships formed at that time. (SLD)

Leviton, Laura C.

2003-01-01

43

Turbellaria of Northern Alaska and Northwestern Canada.  

National Technical Information Service (NTIS)

Five species of turbellarians are recorded for northwestern arctic to subarctic America, all of which belong to different genera, viz. Castrada spinulosa Hofsten 1907, Mesostoma lingua (ABILDGAARD) 1789, Gyratrix hermaphroditus EHRENBERG 1831, Otomesostom...

C. Holmquist

1967-01-01

44

Growth and demise of Late Carboniferous carbonate platforms in the eastern Cantabrian Zone, Asturias, northwestern Spain  

Microsoft Academic Search

Geometric relationships of seismic-scale stratal patterns observed on aerial photographs of Late Carboniferous carbonate platforms in the Cuera Region in Asturias, northwestern Spain, allow the identification of two discrete stages of platform development with different styles of deposition. The first phase, represented by the Bashkirian Valdeteja Formation, is characterized by progradation of more than 10 km with steep clinoforms of

Juan R. Bahamonde; Juan R. Colmenero; Carmen Vera

1997-01-01

45

Geochemistry and petrogenesis of late proterozoic volcanic rocks from north-western Africa  

Microsoft Academic Search

The Upper Proterozoic volcanism of northwestern Africa is characterized by the predominance of calc-alkaline rocks. Volcanics with tholeiitic affinities and alkali basalts are rare. The geochemistry and the relative proportions of calc-alkaline rocktypes in the Silet zone (Algeria) and the Ouarzazate formation (Morocco) are similar to those of recent island arc suites where basalts are most abundant while in the

M. Chikhaoui; C. Dupuy; J. Dostal

1980-01-01

46

Subduction of the Eastern Panama Basin and Seismotectonics of Northwestern South America  

Microsoft Academic Search

Spreading along the Cocos-Nazca plate boundary since the breakup of the Farallon plate in the Miocene has resulted in the formation of the Panama basin and a complex interaction of plates in and near northwestern South America. Current plate boundaries have been defined, and segments of subducted lithosphere identified through selection of hypocentral locations of earthquakes, considering only welllocated events,

Wayne D. Pennington

1981-01-01

47

Modeling an air pollution episode in northwestern United States: identifying the effect of nitrogen oxide and volatile organic compound emission changes on air pollutants formation using direct sensitivity analysis.  

PubMed

Air quality impacts of volatile organic compound (VOC) and nitrogen oxide (NO(x)) emissions from major sources over the northwestern United States are simulated. The comprehensive nested modeling system comprises three models: Community Multiscale Air Quality (CMAQ), Weather Research and Forecasting (WRF), and Sparse Matrix Operator Kernel Emissions (SMOKE). In addition, the decoupled direct method in three dimensions (DDM-3D) is used to determine the sensitivities of pollutant concentrations to changes in precursor emissions during a severe smog episode in July of 2006. The average simulated 8-hr daily maximum O3 concentration is 48.9 ppb, with 1-hr O3 maxima up to 106 ppb (40 km southeast of Seattle). The average simulated PM2.5 (particulate matter with an aerodynamic diameter < 2.5 microm) concentration at the measurement sites is 9.06 microg m(-3), which is in good agreement with the observed concentration (8.06 microg m(-3)). In urban areas (i.e., Seattle, Vancouver, etc.), the model predicts that, on average, a reduction of NO(x) emissions is simulated to lead to an increase in average 8-hr daily maximum O3 concentrations, and will be most prominent in Seattle (where the greatest sensitivity is -O.2 ppb per % change of mobile sources). On the other hand, decreasing NO(x) emissions is simulated to decrease the 8-hr maximum O3 concentrations in remote and forested areas. Decreased NO(x) emissions are simulated to slightly increase PM2.5 in major urban areas. In urban areas, a decrease in VOC emissions will result in a decrease of 8-hr maximum O3 concentrations. The impact of decreased VOC emissions from biogenic, mobile, nonroad, and area sources on average 8-hr daily maximum O3 concentrations is up to 0.05 ppb decrease per % of emission change, each. Decreased emissions of VOCs decrease average PM2.5 concentrations in the entire modeling domain. In major cities, PM2.5 concentrations are more sensitive to emissions of VOCs from biogenic sources than other sources of VOCs. These results can be used to interpret the effectiveness of VOC or NO(x) controls over pollutant concentrations, especially for localities that may exceed National Ambient Air Quality Standards (NAAQS). Implications: The effect of NO(x) and VOC controls on ozone and PM2.5 concentrations in the northwestern United States is examined using the decoupled direct method in three dimensions (DDM-3D) in a state-of-the-art three-dimensional chemical transport model (CMAQ). NO(x) controls are predicted to increase PM2.5 and ozone in major urban areas and decrease ozone in more remote and forested areas. VOC reductions are helpful in reducing ozone and PM2.5 concentrations in urban areas. Biogenic VOC sources have the largest impact on O3 and PM2.5 concentrations. PMID:23155861

Tsimpidi, Alexandra P; Trail, Marcus; Hu, Yongtao; Nenes, Athanasios; Russell, Armistead G

2012-10-01

48

The geochemistry of the Fox Hills-Basal Hell Creek Aquifer in southwestern North Dakota and northwestern South Dakota  

Microsoft Academic Search

The Late Cretaceous Fox Hills Formation and the basal portion of the overlying Hell Creek Formation constitute an important aquifer in the Fort Union coal region. Throughout most of southwestern North Dakota and northwestern South Dakota the aquifer is at depths ranging from 1000 to 2000 ft, except for exposures along the Cedar Creek anticline. Water flows in the aquifer

Donald C. Thorstenson; Donald W. Fisher; Mack G. Croft

1979-01-01

49

Development of the Permian-Triassic unconformity in southwestern Utah, southeastern Nevada and northwestern Arizona  

Microsoft Academic Search

Development of positive areas, that are oriented northwest-southeast in south-western Utah, southeastern Nevada, and northwestern Arizona, are indicated by the depositional patterns of the Rock Canyon Conglomerate and facies changes produced by on-lapping during the deposition of the Timpoweap, Lower Red, and Virgin Limestone Members of the Moenkopi Formation. The lack of facies change in the Kaibab Formation indicates that

Nielson

1993-01-01

50

Guillain-Barré syndrome in northwestern China.  

PubMed

We reviewed 100 patients with Guillan-Barré syndrome (GBS) from 1994 to 2000 from northwestern China. We examined clinical and electro-diagnostics features and compared them to patients from Europe, North America and northern China. Results indicated that among 100 patients with GBS, the demyelinating pattern was present in 51 patients, the axonal pattern in 25 patients, and 8 patients were inexcitable, 12 patients equivocal and 4 patients normal. The electrophysiological and clinical features of various subtypes of GBS in northwestern China seemed to be different in some ways from those in western countries and in northern China. However, in northwestern China, the demyelinating pattern is the major electrophysiological subtype. PMID:11721293

Jiang, W; Wang, H D; Huang, Y G; Wan, Q; Xu, Y; Wu, B R

2001-01-01

51

Crustal structure of the northwestern United States  

Microsoft Academic Search

The region of the northwestern United States between the Rocky Mountains and the Cascade Range, which is about 1000 km in length and is between 400 and 700 km in width was examined. The western edge of the study area occupies a position approximately 250 km east of the subduction zone between the Juan De Fuca and North American lithospheric

Rufus Douglas Catchings

1987-01-01

52

Peralkaline Silicic Volcanic Rocks in Northwestern Nevada  

Microsoft Academic Search

Late Tertiary silicic ashflow tuffs and lavas peralkaline in chemical character (atomic Na + K greater than Al), mainly comendites, occur over wide areas in northwestern Nevada and appear to be widespread in southeastern Oregon. Such peralkaline rocks-which are not uncommon in the western United States-and other chemically unusual silicic rocks are found near the margins rather than toward the

Donald C. Noble; David W. Chipman; David L. Giles

1968-01-01

53

Middle proterozoic compressional orogen in northwestern Canada  

Microsoft Academic Search

Evidence from seismic reflection profiling, drill holes, potential field measurements and regional geology shows that an east verging Proterozoic thin-skinned thrust and fold belt is situated beneath the Interior Platform of northwestern Canada. Balanced cross sections and associated palinspastic reconstructions provide constraints on the extent of the shortening in the thrust belt and suggest that at least 50-90 km of

Frederick A. Cook

1988-01-01

54

Cysticercosis of slaughtered cattle in northwestern Ethiopia  

Microsoft Academic Search

The occurrence of cysticercosis due to Taenia saginata in cattle slaughtered for meat in Amhara National Regional State, northwestern Ethiopia between September 2005 and February 2007 was investigated. Routine meat inspection of various organs of 4456 cattle in eight abattoirs of this region showed that 824 (18.49%) were infected with Cysticercus bovis. The occurrence rate did not vary significantly from

Nigatu Kebede

2008-01-01

55

Northwestern Hawaiian Islands Coral Reef Ecosystem Reserve  

NSDL National Science Digital Library

This page describes the unique Northwestern Hawaiian Islands (NWHI) Ecosystem Reserve. Provides resources focused on NWHI coral reef ecosystems, and introductions to reef research, management and protection activities. Educational outreach includes: teacher workshops; student activities, and a Discovery Center in Hilo, Hawaii that features exhibits and activities for schools and the public.

2011-04-22

56

Northwestern Hawaiian Islands Coral Reef Ecosystem Reserve  

NSDL National Science Digital Library

Describes the unique Northwestern Hawaiian Islands (NWHI) Ecosystem Reserve. Provides resources focused on NWHI coral reef ecosystems, and introductions to reef research, management and protection activities. Educational outreach includes: teacher workshops; student activities, and a Discovery Center in Hilo, Hawaii that features exhibits and activities for schools and the public.

57

The age and tectonic setting of the Puncoviscana Formation in northwestern Argentina: An accretionary complex related to Early Cambrian closure of the Puncoviscana Ocean and accretion of the Arequipa-Antofalla block  

NASA Astrophysics Data System (ADS)

TIMS and SHRIMP U-Pb zircon geochronology of selected parts of the Puncoviscana Formation suggest its deposition took place mainly during the Early Cambrian, coeval with 540-535 Ma calc-alkaline Pampean arc volcanism mainly preserved as tuff beds in the oldest identified parts of this unit. Syn- to post-tectonic plutons constrains the Tilcarian-Pampean orogeny to have occurred between ca. 530 Ma and deposition of the unconformably overlying Middle-Upper Cambrian Meson Group. Deposition of the Puncoviscana Formation continued after the onset of the Tilcarian-Pampean orogeny. We propose that the Puncoviscana Formation rocks older than 530 Ma were deposited in the arc-trench gap of the west-facing Pampean arc and/or the associated trench, whereas the rocks younger than 530 Ma were deposited in a syn-collision foreland basin. The Puncoviscana Formation rocks were progressively assembled into a west-younging accretionary complex, consistent with the style of deformation and low-grade metamorphism. The age of the syn-collision plutons (?530 Ma) suggest the foredeep deposits record the transition from trench to foreland basin, due to arrival of the Arequipa-Antofalla block at the west-facing trench at ca. 530 Ma. Our geochronological and Pb-isotope investigations suggest that the Arequipa-Antofalla terrane was a coherent, ribbon-shaped crustal block that also included the western part of the Pampia terrane. A compilation of existing U-Pb zircon studies suggests that the Pampean arc extended along the length of the proto-Andean margin of West Gondwana, represented by the previously amalgamated Amazonia and Rio de La Plata cratons, and probably was initiated during the late Ediacaran after 600 Ma. Following earlier workers, we reaffirm that the Arequipa-Antofalla block was originally separating Laurentia and Amazonia in Rodinia. It probably rifted from Laurentia during the Ediacaran between 600 and 570 Ma, following an earlier departure of Amazonia (˜650 Ma?). The separation of Arequipa-Antofalla from Amazonia and Laurentia opened the Puncoviscana and Iapetus oceans respectively.

Escayola, Mónica P.; van Staal, Cees R.; Davis, William J.

2011-12-01

58

Carnian (upper triassic) sponge mounds of the Northwestern Sichuan Basin, China: Stratigraphy, facies and paleoecology  

Microsoft Academic Search

Summary  Carnian reef mounds with abundant and highly diverse siliceous sponges (Lyssacinosa and “Lithistida”) occur at the northwestern\\u000a margin of the Sichuan Basin (Anxian and Mianzhu counties), Southern China. Triassic sediments comprise Ladinian to early Norian\\u000a deposits. Sponge mounds are confined to the Upper Member of the Carnian Hanwang Formation, being late Carnian in age.\\u000a \\u000a The mounds correspond to elliptical carbonate

Wu Xichun

1989-01-01

59

Overpressure distribution and pressuring mechanism on the southern margin of the Junggar Basin, Northwestern China  

Microsoft Academic Search

On the basis of the pressure data obtained from the southern margin of the Junggar Basin, Northwestern China, the distribution\\u000a and evolution of overpressures in high permeable sandy and in low-permeability shale formations are characterized. The evolution\\u000a of overpressures in various structural processes, especially in erosion and mechanical deformation, is quantified by numerical\\u000a modeling studies. The modeling results show that

Xiaorong Luo; Loujun Liu; Xueyi Li

2006-01-01

60

Dust Storm Reduction due to Precipitation and Temperature Enhancement in Northwestern China: A Direct Climatic Impact of Absorbing Aerosols  

Microsoft Academic Search

Dust storms originating in the Gobi desert and northwestern China critically impact weather, climate, and public health in China and neighboring Pacific Rim countries. The frequent occurrence of dust storms has been attributed to both deforestation and the changing environment. Dust storm formation is determined by a number of factors, including dryness, wind field, soil type, and precipitation, with precipitation

Y. Gu; K. Liou; W. Chen; H. Liao

2009-01-01

61

Peralkaline silicic volcanic rocks in northwestern nevada.  

PubMed

Late Tertiary silicic ashflow tuffs and lavas peralkaline in chemical character (atomic Na + K greater than Al), mainly comendites, occur over wide areas in northwestern Nevada and appear to be widespread in southeastern Oregon. Such peralkaline rocks-which are not uncommon in the western United States-and other chemically unusual silicic rocks are found near the margins rather than toward the center of the Great Basin. PMID:17800671

Noble, D C; Chipman, D W; Giles, D L

1968-06-21

62

Lake Trout Movements in Northwestern Lake Michigan  

Microsoft Academic Search

We quantified the distance that lake troutSalvelinus namaycushmoved in northwestern Lake Michigan and examined (1) the directional preference and (2) the effect of population density on movement. Lake trout were captured in spring and fall 1983-1996, tagged with Floy anchor tags, and recaptured during subsequent agency sampling and by commercial fishers and anglers during 1983-1997. Angler recaptures were used to

Patrick J. Schmalz; Michael J. Hansen; Mark E. Holey; Patrick C. McKee; Michael L. Toneys

2002-01-01

63

40 CFR 81.126 - Northwestern Oklahoma Intrastate Air Quality Control Region.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Northwestern Oklahoma Intrastate Air Quality Control Region...Regions § 81.126 Northwestern Oklahoma Intrastate Air Quality Control Region. The Northwestern Oklahoma Intrastate Air Quality...

2013-07-01

64

Exploration strategy in Keg River carbonates of northwestern Alberta, Canada  

SciTech Connect

The analysis of reservoir quality and seal capacity of the Middle Devonian Keg River carbonate reservoirs in northwestern Alberta requires facies studies of rock units of the Keg River Formation and of the overlying Muskeg and Sulphur Point formations. Using lithologic criteria, faunal type, and stratigraphic positions, the entire sequence is subdivided into ten major facies. The system used is that of standard facies belts with second-order modification to Wilson's terminology. These facies are (from basin to land): basin, open sea shelf, toe of slope, foreslope, organic buildup, shoal lime sand, open lagoon, restricted lagoon, tidal flats, and sabkha evaporites. The upper member of the Keg River Formation is the main hydrocarbon reservoir in the study area. It consists of floatstone, rudstone, and boundstone with wackestone, packstone, and grainstone matrix. The principal faunal constituents are crinoids, brachiopods, stromatoporoids, corals, and stachyodes. The reservoir porosity is of primary intergranular and intragranular and secondary vugular textures. The upper Keg River member is composed of two major facies: patch reefs and banks. Both facies are formed in an open lagoon environment fronted by Presqu'ile barrier to the west-northwest. Water depth was the main factor in controlling the distribution of the bank and patch reef facies. Patch reefs were developed in areas of deeper water, whereas banks were formed in shallower areas of the open lagoon. Recent analogs of the Keg River buildups are found on the Bermuda Platform and Belize Shelf. A direct relationship exists between the thickness of overlying anhydrites of the Muskeg Formation and hydrocarbon occurrences in the Keg River Formation. Generally in areas where patch reefs are developed, the thickness of the anhydrite is more than 30 ft. However, areas of bank are covered by less than 30 ft of anhydrite.

Majid, A.H.

1987-05-01

65

Deformations of the northwestern Pacific plate  

NASA Astrophysics Data System (ADS)

The style and age of deformations of the sedimentary cover and basaltic basement in the northwestern basin of the Pacific Ocean were studied based on seismic data coordinated with the results of deep-water drilling. The deformations are widespread not only on the oceanic slope of the trench as a plate boundary, but also within the plate especially close to the large Hokkaido, Tuscarora, and Seismikov fracture zones and the Hokkaido Swell. The most intense deformation took place at the Pliocene-Quaternary boundary. Abundant diapirs related to the plastic serpentinite layer at base of the crust indicate that gravity tectonics primarily develops here.

Patrikeev, V. N.

2013-09-01

66

Uranium in saline lakes of Northwestern Mongolia  

NASA Astrophysics Data System (ADS)

Analysis of major- and trace-element compositions of water in hypersaline soda closed basin lakes of Northwestern Mongolia and Chuya basin (Gorny Altai) shows high enrichment in 238U (up to 1 mg/l). Proceeding from new data, uranium accumulation in water has been attributed to (i) location of the lakes and their watersheds in potential provinces of U-bearing rocks and (ii) uranium complexing with carbonate in presence of carbonate (bicarbonate) anions. Among the explored hypersaline soda lakes of the area, the greatest uranium resources are stored in Lake Hyargas Nuur (about 6000 ton).

Isupov, V. P.; Vladimirov, A. G.; Lyakhov, N. Z.; Shvartsev, S. L.; Ariunbileg, S.; Kolpakova, M. N.; Shatskaya, S. S.; Chupakhina, L. E.; Kuibida, L. V.; Moroz, E. N.

2011-03-01

67

Cretaceous magnetizations in northwestern Nevada and tectonic implications  

Microsoft Academic Search

Paleozoic and Mesozoic arc-related rocks of the Black Rock Desert region of northwestern Nevada have acquired a very stable postfolding secondary magnetization, probably in Late Cretaceous time. The remagnetization, which appears to be of regional extent, probably accompanied emplacement of granitic plutons in a northeast-trending belt across northwestern Nevada near the end of Mesozoic time. The region has experienced no

Branch J. Russell; Myrl E. Beck Jr.; Russell F. Burmester; R. C. Speed

1982-01-01

68

Spontaneously settled refugees in Northwestern Province, Zambia.  

PubMed

The UN High Commissioner for Refugees (UNHCR) commissioned researchers from the University of Zambia to conduct a socioeconomic survey and census of "spontaneously settled" Zairean and Angolan refugees in the Northwestern Province of Zambia in 1982. The sample consisted of 188 Angolans, 201 Zaireans, and 2 South Africans. The difficulties experienced by refugees in Northwestern Province in achieving integration were related to a combination of factors including the lack of a clear national policy on refugees and refugee status, a national concern for maintaining security, the popular belief that aliens are responsible for an increasing crime rate, the desire by immigration officials for stricter laws to control alien infiltration, conflict between traditional and modern leaders, and Zambia's deteriorating economic situation. In spite of the problems described, the integration of refugees into existing communities is a desirable goal and should be encouraged. One should not assume that self-settling refugees are able to live with ethnic kin, receive assistance and hospitality, and thus are better off than those in camps. The Zambian case provides ample evidence that integration is not easy even with kin support, shared ethnicity, language, and historical connections. Moreover, given the fact that Zambia will continue to receive refugees it is vital that there is a well defined refugee policy and an administrative mechanism for implementing that policy at all levels. This will be particularly important in Zambia as it will undoubtedly continue to receive large influxes of refugees, from countries such as Namibia, Uganda, Angola, Mozambique, and South Africa. PMID:12267853

Freund, P J; Kalumba, K

1986-01-01

69

Seismicity and seismotectonics of northwestern Libya  

NASA Astrophysics Data System (ADS)

As a result of the relative motion of the African and European plates, Libya has experienced a considerable intraplate tectonism particularly at its northern regions. In this study we investigate the seismic activity and the seismotectonics of northwestern Libya. The northwestern part of Libya has experienced a number of earthquakes including earthquakes of magnitude greater than six. The seismic activity shows three major seismic trends. The first trend is a NW-SE trending cluster of seismicity coinciding with the eastern boarder of the Hun Graben. A second trend is also a NW-SE direction in the offshore area northern of the city of Misuratah. The third cluster was located in the western Gulf of Sirt. The rest of seismicity is diffuse either offshore or in land, with no good correlation with well-mapped faults. Fault plane solution was estimated for 17 earthquakes recorded by the Libyan National Seismograph Network. Fault plain solution for the first area suggests oblique reverse to strike slip faulting with dominant compressional P-axes trending NW-SE and NE-SW. The second area suggests strike-slip to reverse faulting with dominant compressional P-axes trending NW-SE and NE-SW. Fault plain solution for 3 earthquakes located southern Tripoli suggests an oblique normal faulting with dominant compressional P-axes trending E-W to NE-SW. Further west to the Tunisian boarder, fault plain solution suggests oblique normal faulting with dominant compressional P-axes trending NW-SE.

Ben Suleman, Abdunnur; Elmeladi, Abdalla

2014-05-01

70

Upper Campanian-lower Maastrichtian sections of the northwestern Rostov region. Article 1. Description, paleontological assemblages, and lithobiostratigraphy  

NASA Astrophysics Data System (ADS)

Four upper Campanian-lower Maastrichtian reference sections are described in the Glubokaya and Kalitva river basins and in the Znamenka 1-A Borehole located in the northwestern Rostov region. The sections are composed of the upper Campanian Kagal'nik, Belgorod, Pavlovka, Sukhodol and lower Maastrichtian Efremovo-Stepanovka formations. They are characterized by successive stratigraphically significant macro- and microfossil assemblages: belemnites, calcareous nannoplankton, benthic foraminifers, and radiolarians. The Pavlovka and, particularly, Sukhodol formations contain a specific assemblage of coarsely-agglutinated benthic foraminifers. The first data obtained on radiolarians in upper Campanian-lower Maastrichtian sections of the northwestern Rostov region revealed four assemblages, two of which were previously unknown from Upper Cretaceous sediments of the East European Platform. Most sections enclose a hiatus at the base of the Sukhodol Formation, which comprises two upper Campanian benthic foraminiferal zones. The problem of recognition of the lower Maastrichtian boundary on the East European Platform is considered in accordance with international GSSP requirements.

Benyamovskiy, V. N.; Alekseev, A. S.; Ovechkina, M. N.; Vishnevskaya, V. S.; Podgaetskii, A. V.; Pronin, V. G.

2012-07-01

71

Cysticercosis of slaughtered cattle in northwestern Ethiopia.  

PubMed

The occurrence of cysticercosis due to Taenia saginata in cattle slaughtered for meat in Amhara National Regional State, northwestern Ethiopia between September 2005 and February 2007 was investigated. Routine meat inspection of various organs of 4456 cattle in eight abattoirs of this region showed that 824 (18.49%) were infected with Cysticercus bovis. The occurrence rate did not vary significantly from abattoir to abattoir (P>0.5). The tongue, masseter muscles, heart muscles, triceps muscles and thigh muscles were the main predilection sites of the cysts. Of 4102 male cattle, examined, 768 (18.72%) had cysts of C. bovis while 56 (15.82%) of the 354 female animals investigated were infected. The animals slaughtered were all adults. No significant difference in occurrence was recorded between the sexes. Monthly occurrence of the cysts in the animals revealed a rise of infected animals during the dry season. PMID:18321540

Kebede, Nigatu

2008-12-01

72

Institute for Policy Research: Northwestern University  

NSDL National Science Digital Library

Founded in 1968, the Institute for Policy Research (IPR) at Northwestern University is an interdisciplinary public policy research institute that supports dozens of research projects dealing with a range of issues, including poverty, race, adolescent studies, philanthropy, and community development. The site will be invaluable to persons interested in these fields (especially those interested in the Midwest and Chicago), as complete information is offered about ongoing research programs, affiliated centers (such as the Joint Center for Poverty Research), and a list of staff members and faculty associates. As with many policy research institutes, the publications section contains the most important substantive material, as users may browse working papers, policy briefs, newsletters, and publications from affiliated centers. The IPR Working Paper series extends back until 1995, and contains over 100 reports in total.

73

Bioassay of kinship in northwestern Europe.  

PubMed

Kinship of Barra (Outer Hebrides) is bioassayed as 0.0096 relative to northwestern Europe, in reasonable agreement with prediction of 0.008 relative to Britain. The exponential decline of kinship with distance is similar to Scandinavia. Kinship of larger populations is consistent with predictions from isolates. Kinship is largely due to local drift rather than Norse admixture, the estimate of which is obscured by drift and appears highly unreliable. Other populations in northwest Europe, including Iceland, Lewis and Orkney, give estimates of kinship which reflect drift and geography, but also do not provide reliable estimates of admixture. Bioassay of kinship from gene frequencies gives observations to be explained in terms of migration and drift, but contributes nothing to the question of whether polymorphism in the species is maintained by neutral mutation or selection. Although the latter is on various grounds more likely, no calculations based on gene frequency distribution can provide critical evidence. PMID:596833

Morton, N E; Dick, H M; Allan, N C; Izatt, M M; Hill, R; Yee, S

1977-10-01

74

Northwestern Mexico as photographed from Skylab  

NASA Technical Reports Server (NTRS)

An oblique view of northwestern Mexico (30.0N, 113.5W), as photographed from the Skylab space station in Earth orbit by one of the Skylab 4 crewmen. This photograph was taken on a seep down the coast to document the fault patterns of southern California and northwest Mexico. The specific reason for the picture was to see of the Agua Blanca Fault in Baja California extends to the east toward the Gulf of California. No such extension was found. The fault appeard to disappear into an area of sand and heavily eroded material that obscured any feature that might be present deeper. This area of sand and loose material is the light-colored area in the center of Baja at the extreme north part of the photograph.

1975-01-01

75

The northwestern ejecta knot in SN 1006  

NASA Astrophysics Data System (ADS)

Aims: We want to probe the physics of fast collision-less shocks in supernova remnants. We are interested in the non-equilibration of temperatures and particle acceleration. Specifically, we aim to measure the oxygen temperature with regards to the electron temperature. In addition, we search for synchrotron emission in the northwestern thermal rim. Methods: This study is part of a dedicated deep observational project of SN 1006 using XMM-Newton, which provides us with the currently best resolution spectra of the bright northwestern oxygen knot. We aim to use the reflection grating spectrometer to measure the thermal broadening of the O vii line triplet by convolving the emission profile of the remnant with the response matrix. Results: The line broadening was measured as ?e = 2.4 ± 0.3 eV, corresponding to an oxygen temperature of 275-63+72 keV. From the EPIC spectra we obtain an electron temperature of 1.35 ± 0.10 keV. The difference in temperature between the species provides further evidence of non-equilibration of temperatures in a shock. In addition, we find evidence of a bow shock that emits X-ray synchrotron radiation, which is at odds with the general idea that because of the magnetic field orientation only in the NE and SW region, X-ray synchrotron radiation should be emitted. We find an unusual H? and X-ray synchrotron geometry, in that the H? emission peaks downstream of the synchrotron emission. This may be an indication of a peculiar H? shock in which the density is lower and the neutral fraction is higher than in other supernova remnants, resulting in a peak in H? emission further downstream of the shock.

Broersen, S.; Vink, J.; Miceli, M.; Bocchino, F.; Maurin, G.; Decourchelle, A.

2013-04-01

76

Petroleum in the Junggar basin, northwestern China  

NASA Astrophysics Data System (ADS)

The Junggar basin occupies a large triangular area of some 130 000 km 2 in northwestern China. Situated between the Altay Shan (Altay Range) on the northeast and the Tian Shan (Tian Range) on the southwest, and between lesser ranges around the remainder of its periphery, the Junggar basin is completely intermontane. Its history as a basin began in the Permian, and continued as various uplifts and downwarps evolved. Through the Paleozoic the characteristics of the Junggar basin area were largely geosynclinal and marine. Its post-Permian development took place exclusively in continental regimes. Inhabitants of the Junggar basin have known and utilized its numerous oil and asphalt seeps and its spectacular spreads of asphalt for more than 2000 years, especially in the Karamay-Urho thrust belt near the northwestern rim. The first discovery of oil in the modern sense came at Dushanzi, one of the steeply folded anticlines of theÜrümqi foredeep near the southern rim. The first shallow oil in the Karamay-Urho thrust belt came in 1937, followed by commercial production in the Karamay field in 1955. Output continued to be modest until wells were drilled through local thrusts and reverse faults in the early 1980s. By 1985, cumulative production of the Karamay group of fields had reached 42,000,000 t (metric tonnes) (306,000,000 bbl), with a calculated minimum ultimate recovery of 280,000,000 t (2 billion bbl). Principal production comes from Permian and Triassic strata in continental facies. Apart from marine Mid and Upper Carboniferous strata, source rocks occur mainly in fine-grained lacustrine detrital beds of the Permian, the Triassic, the Jurassic and the Tertiary. Several uplifts and downwarps elsewhere in the Junggar basin remain to be drilled comprehensively. Results from such drilling may enhance the very important position that the Junggar already has attained in the hierarchy of China's onshore basins.

Taner, Irfan; Kamen-Kaye, Maurice; Meyerhoff, Arthur A.

77

Geomorphological context of the basins of Northwestern Peninsular Malaysia  

NASA Astrophysics Data System (ADS)

Geomorphological context of the basins of Northwestern Peninsular Malaysia Benjamin Sautter, Manuel Pubellier, David Menier Department of Petroleum Geosciences, Universiti Teknologi PETRONAS CNRS-UMR 8538, Ecole Normale Supérieure, 24, Rue Lhomond, 75231, Paris Cedex 05, France Petroleum basins of Western Malaysia are poorly known and their formation is controlled by the Tertiary stress variations applied on Mesozoic basement structures. Among these are the Paleozoic-Mesozoic Bentong Raub, Inthanon, and Nan suture zones. By the end of Mesozoic times, the arrival of Indian plate was accompanied by strike slip deformation, accommodated by several Major Faults (Sagaing, Three Pagodas, Mae Ping, Red River, Ranong and Klong Marui Faults). Due to changes in the boundary forces, these areas of weakness (faults) were reactivated during the Tertiary, leading to the opening of basins in most of Sundaland. Within this framework, while most of the Sundaland records stretching of the crust and opening of basins (SCS, Malay, Penyu, Natuna, Mergui) during the Cenozoics, Peninsular Malaysia and the Strait of Malacca are considered to be in tectonic quiescence by most of the authors. We present the geomorphology of the Northwestern Malaysia Peninsula with emphasis on the deformations onshore from the Bentong Raub Suture Zone to the Bok Bak Fault, via the Kinta Valley, and offshore from the Port Klang Graben to the North Penang Graben. By analyzing Digital Elevation Model from ASTER and SRTM data, two main directions of fractures in the granitic plutons are highlighted: NW-SE to W-E sigmoidal faults and N-S to NE-SW linear fractures which seem to cross-cut the others. In the field in the area of the Kinta Valley (Western Belt, NW Peninsular Malaysia), granitic bodies show intense fracturation reflecting several stages of deformation. The granites are generally syntectonic and do not cut fully across the Late Paleozoic platform limestone. Two sets of fractures (NW-SE and NE-SW) appear more penetrative in both granitic and limestone units. On most of the studied outcrops, exfoliation fractures are reactivated into normal faults. Deformation is particularly severe at the contact of the granites and the sediments which is underlined by cataclasic quartz dykes and hornfelds. Off-shore, in the Straits of Malacca, nine tertiary half-grabens are present, all oriented in N-S to NE-SW direction with N-S boundary faults on their western margin. We propose a tectonic scenario for the north-western Malaysia Peninsula according to which the northward motion of India induced first right-lateral transpressionnal tectonics at the End of the Mesozoics (Cretaceous early Tertiary). This system is illustrated in the NW-SE trending fractures of the Main Range Batholith and other Triassic plutons within a system bounded and controlled by the Bok Bak Fault, the KL fault zone and the Bentong Raub Suture Zone. Later, a second stage of transtension led to the opening of the en echelon onshore basins in a tear-faults system, and to the opening of half grabens offshore in the Straits of Malacca.

Sautter, Benjamin; Pubellier, Manuel; Menier, David

2014-05-01

78

A Synoptic Climatoloty for Snowstorms in Northwestern Nevada.  

National Technical Information Service (NTIS)

The purpose of this study is to provide a climatological aid for forecasting snow in northwestern Nevada. A total of 112 snowstorms affecting Reno, Lovelock, or Winnemucca were analyzed to determine if these storms could be categorized into separate types...

B. L. Nelson P. M. Fransioli C. M. Sakamoto

1972-01-01

79

Five Modern Races of Maize from Northwestern Mexico: Archaeological Implications.  

National Technical Information Service (NTIS)

Although it is difficult to separate collections of maize from northwestern Mexico into the racial categories recognized by the cultivators, cluster analysis has proven to be an effective means of separating collections into racial groups. The effects of ...

B. F. Benz

1981-01-01

80

A Psychometric Evaluation of the Northwestern Syntax Screening Test  

ERIC Educational Resources Information Center

In evaluating the Northwestern Syntax Screening Test (a test for assessing expressive and receptive grammar in preschool and primary age children), the author points out problems with the test norms, reliability, and validity. (SBH)

Arndt, William B.

1977-01-01

81

Hawaiian Monk Seal in the Northwestern Hawaiian Islands, 1996.  

National Technical Information Service (NTIS)

In 1996, field studies of the endangered Hawaiian monk seal (Monachus schauinslandi) were conducted at all of its main reproductive sites in the Northwestern Hawaiian Islands. These studies provide information necessary to evaluate (1) the status and tren...

T. C. Johanos T. J. Ragen

1999-01-01

82

Hawaiian Monk Seal in the Northwestern Hawaiian Islands, 1995.  

National Technical Information Service (NTIS)

In 1995, field studies of the endangered Hawaiian monk seal (Monachus schauinslandi) were conducted at all of its main reproductive sites in the Northwestern Hawaiian Islands. These studies provide information necessary to evaluate (1) the status and tren...

T. C. Johanos T. J. Ragen

1997-01-01

83

Stratigraphy and palaeoceanography of the Cenomanian-Turonian Boundary Event in Oued Mellegue, north-western Tunisia  

Microsoft Academic Search

An expanded Cenomanian-Turonian section along Oued Mellegue in north-western Tunisia provides a high-resolution record of the latest Cenomanian Oceanic Anoxic Event in an upper bathyal, pelagic to hemipelagic environment. A rapid >2|Pg positive excursion in |MD13C starts at the base of the organic-rich Bahloul Formation, which represents the Cenomanian-Turonian Boundary Event (CTBE) in Tunisia. The transition to a dysaerobic environment

Alexandra J Nederbragt; Andrea Fiorentino

1999-01-01

84

Geomagnetic variation anomalies in north-western Italy  

Microsoft Academic Search

A preliminary geomagnetic variation data analysis has been made in the Piedmont-Ligurian area in north-western Italy. Data were collected by means of two instruments: an Askania portable variograph and a LaCour fixed station operated in the Roburent geomagnetic observatory. The portable variograph has been moved to several locations in north-western Italy. Parkinson vectors were drawn for 8, 20 and 60

Emanuele Bozzo; Antonio Meloni

1989-01-01

85

The hydrocarbon potential, thermal maturity, sequence stratigraphic setting and depositional palaeoenvironment of carbonaceous shale and lignite successions of Panandhro, northwestern Kutch Basin, Gujarat, Western India  

Microsoft Academic Search

The objective of the present paper is to provide geochemical and palynological data to characterize lignites and carbonaceous shales from Panandhro, northwestern Kutch Basin, Gujarat, Western India, in terms of their hydrocarbon potential, thermal maturity, sequence stratigraphic settings and depositional palaeoenvironment. The samples, collected in Panandhro lignite mine, belong to Naredi Formation of Late Paleocene-Early Eocene age. The geochemical results

Vinay K. Sahay

2011-01-01

86

Oil and gas developments in eastern and northwestern Colorado in 1984  

SciTech Connect

Drilling activity in eastern and northwestern Colorado was up approximately 10% from 1430 wells in 1983 to 1589 wells in 1984. This increase in total wells drilled resulted mainly from development activity. The success rate for the 488 exploratory wells drilled in 1984 was 24%, down about 7% from the 1983 level of 31%. Activity in eastern Colorado focused on Pennsylvanian and Mississippian rocks along the Las Animas arch and northern Hugoton embayment. Drilling for Cretaceous formations in the Denver basin increased with much of the new activity centered around the Codell sandstone and Niobrara Formation near Greeley. Significant new Niobrara production was established in northern Weld County. In the San Luis Valley of south-central Colorado, oil shows were reported for the first time in the Cretaceous Dakota Formation beneath volcanic rocks. 1 figure, 2 tables.

Ligrani, L.D.; Adams, C.W.; Nibbelink, K.A.

1985-10-01

87

Northwestern Tharsis Latent Outflow Activity Mars  

NASA Technical Reports Server (NTRS)

Previously defined outflow channels, which are indicated by relict landforms similar to those observed on Earth, signify ancient catastrophic flood events on Mars. These conspicuous geomorphic features are some of the most remarkable yet profound discoveries made by geologists to date. These outflow channels, which debouched tremendous volumes of water into topographic lows such as Chryse, Utopia, Elysium, and Hellas Planitiae, may represent the beginning of warmer and wetter climatic periods unlike the present-day cold and dry Mars. In addition to the previously identified outflow channels, observations permitted by the newly acquired Mars Orbiter Laser Altimeter (MOLA) data have revealed a system of gigantic valleys, referred to as the northwestern slope valleys (NSV), that are located to the northwest of a huge shield volcano, Arsia Mons, western hemisphere of Mars. These features generally correspond spatially to gravity lows similar to the easternmost, circum-Chryse outflow channel systems. Geologic investigations of the Tharsis region suggest that the large valley system pre-dates the construction of Arsia Mons and its extensive associated lava flows of mainly Late Hesperian and Amazonian age and coincides stratigraphically with the early development of the circum-Chryse outflow channel systems that debouch into Chryse Planitia. This newly identified system, the NSV, potentially signifies the largest flood event(s) ever recorded for the solar system. Additional information is contained in original extended abstract.

Dohm, J. M.; Anderson, R. C.; Baker, V. R.; Ferris, J. C.; Hare, T. M.; Strom, R. G.; Rudd, L.; Rice, J. W., Jr.; Scott, D. H.

2000-01-01

88

MISR Images Wildfires in Northwestern US  

NASA Technical Reports Server (NTRS)

MISR image of smoke plumes from devastating wildfires in the northwestern US. This view of the Clearwater and Salmon River Mountains in Idaho was acquired on August 5, 2000 (Terra orbit 3370). The body of water to the left of image center is the Cascade Reservoir, located about 100 km north of Boise and 80 km east of the Snake River. North is at the top, and the image is approximately 380 km across.

In addition to the huge plumes traversing the mountains in the northern part of the image, smoke accumulating in the lower elevation canyons and plains is visible. This image was generated using data from the MISR camera that looks forward at a steep angle (70.5 degrees). The smoke is far more visible when viewed at this highly oblique angle than it would be in a conventional, straight-downward view. In creating this color composite, data from the blue and green MISR bands, acquired at 1.1-km spatial resolution, were digitally 'sharpened' using 275-m resolution data acquired in the red band.

MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Office of Earth Science, Washington, DC. The Terra satellite is managed by NASA's Goddard Space Flight Center, Greenbelt, MD. JPL is a division of the California Institute of Technology.

For more information: http://www-misr.jpl.nasa.gov

2000-01-01

89

Middle Proterozoic compressional orogen in northwestern Canada  

NASA Astrophysics Data System (ADS)

Evidence from seismic reflection profiling, drill holes, potential field measurements and regional geology shows that an east verging Proterozoic thin-skinned thrust and fold belt is situated beneath the Interior Platform of northwestern Canada. Balanced cross sections and associated palinspastic reconstructions provide constraints on the extent of the shortening in the thrust belt and suggest that at least 50-90 km of compression can be accounted for. Although the Proterozoic stratigraphy in the subsurface is not well known, the cross sections are constrained essentially by seismic reflection geometry. Shortening occurred on subhorizontal detachment(s) that lie above the autochthonous (Hudsonian?) basement. Seismic reflection data from the area west of the major thin-skinned thrust structures show that the Proterozoic strata there can be traced for up to 100 km and are characterized by broad, open folds with wavelengths of 10 km or more. Uniform potential field anomalies and subhorizontal seismic reflections further indicate that there are no major crustal boundaries (such as sutures) in the area between the thrust belt and the Campbell uplift near Inuvik, Northwest Territories, that were associated with the thrusting. The detachment(s) that carried the folded and thrust faulted allochthons must therefore extend for a considerable distance to the northwest of the thrust belt. New deep crustal seismic reflection data from the Campbell uplift, however, show evidence for crustalpenetrating Proterozoic structures that dip northwestward and that were probably reactivated during late Paleozoic compression and Mesozoic extension. Taken together, the various data thus indicate that the area from Great Bear Lake to the Campbell uplift (about 400 km) is underlain by a mid-Proterozoic decollement above which the compressional deformation took place, and that the deformation extended to the north side of the present Campbell uplift where steeply north dipping structures indicate that the underlying autochthonous basement is characterized by a ramp structure that was probably associated with the southern edge of a Proterozoic basin.

Cook, Frederick A.

1988-08-01

90

75 FR 7518 - Notice of Public Meeting: Sierra Front Northwestern Basin Resource Advisory Council, Nevada  

Federal Register 2010, 2011, 2012, 2013

...Public Meeting: Sierra Front Northwestern Basin Resource Advisory Council, Nevada AGENCY: Bureau of Land...Management (BLM) Sierra Front-Northwestern Great Basin Resource Advisory...will meet in Carson City, Nevada. The meeting is open...

2010-02-19

91

76 FR 77779 - Availability of Seats for the Northwestern Hawaiian Islands Coral Reef Ecosystem Reserve Advisory...  

Federal Register 2010, 2011, 2012, 2013

...Seats for the Northwestern Hawaiian Islands Coral Reef Ecosystem Reserve Advisory Council...seats on the Northwestern Hawaiian Islands Coral Reef Ecosystem Reserve Advisory Council...SUPPLEMENTARY INFORMATION: The NWHI Coral Reef Ecosystem Reserve is a [[Page...

2011-12-14

92

77 FR 16211 - Availability of Seats for the Northwestern Hawaiian Islands Coral Reef Ecosystem Reserve Advisory...  

Federal Register 2010, 2011, 2012, 2013

...Seats for the Northwestern Hawaiian Islands Coral Reef Ecosystem Reserve Advisory Council...seats on the Northwestern Hawaiian Islands Coral Reef Ecosystem Reserve Advisory Council...SUPPLEMENTARY INFORMATION: The NWHI Coral Reef Ecosystem Reserve is a marine...

2012-03-20

93

The influence of impaction to the third molar mineralization in northwestern Chinese population.  

PubMed

Age estimation by third molar mineralization has been developed for a period of time. Recent studies showed that impaction status has an influence on the rate of the third molar mineralization in Europids and male Black African populations. In this regard, the present study was conducted to determine whether the impaction status could delay the chronological process of third molar mineralization in northwestern Chinese population too. A total of 3,512 digital orthopantomograms of 1,255 male and 2,257 female northwestern Chinese subjects aged from 11 to 26 years were assessed based on the formation stages described by Demirjian et al. with two modifications. Mineralization stage and impaction status were determined for all third molars. Statistical measures were calculated at stages C-H in the male and female gender for both impacted and non-impacted third molars. It was ascertained that the mean ages with impacted third molars at stages C-H were 0.02-1.42 years higher in males and 0.04-1.52 years higher in females than those with non-impacted third molars, but statistical differences were only found at stages C, D, and E in males and stages D and E in females. The probabilities of being under 14, 16, or 18 years of age with non-impacted third molars were all higher than those with impacted third molars. The results prove that impacted third molars show significant slower mineralization than non-impacted ones at stages D and E in both males and females of northwestern Chinese population. It is recommended to consider the influence of impaction on the rate of third molar mineralization for dental age estimation. PMID:24532176

Guo, Yu-cheng; Yan, Chun-xia; Lin, Xing-wei; Zhang, Wen-tao; Zhou, Hong; Pan, Feng; Wei, Lai; Tang, Zheng; Liang, Feng; Chen, Teng

2014-07-01

94

Northwestern researchers develop new way to treat lymphoma without chemotherapy  

Cancer.gov

A new study by Northwestern Medicine researchers shows that synthetic HDL nanoparticles killed B-cell lymphoma, the most common form of the disease, in cultured human cells, and inhibited human B-cell lymphoma tumor growth in mice. The nanoparticle appears to the cancerous lymphoma cell like a preferred meal -- natural HDL. But when the particle engages the cell, it actually plugs it up and blocks cholesterol from entering. Deprived of an essential nutrient, the cell eventually dies. Northwestern is home to the Robert H. Lurie Comprehensive Cancer Center.

95

Stratigraphy, depositional environments, and carbonate petrology of the Toroweap and Kaibab Formations (lower Permian), Grand Canyon region, Arizona  

Microsoft Academic Search

Sediments deposited in northwestern Arizona during Late Leonardian and Early Guadalupian (Permian) were controlled chiefly by an arid climate and the tectonic setting. Eastward thrusting of eugeosynclinal rocks onto miogeosynclinal deposits during Middle Devonian to Early Mississippian had a major influence on shelf sedimentation. The Toroweap and Kaibab formations represent two such platform sequences of northwestern Arizona and southern Utah

R. A. Clark

1981-01-01

96

Oxide Superconductivity Research at Northwestern University  

NASA Astrophysics Data System (ADS)

A short review was presented of a wide range of activities involving the high Tc oxide superconductors at the Northwestern University. Calculations of the charge density associated with the d9 shell of the copper atom in the Cu-O planes and the d8 shell of the copper atoms along the Cu-O lines of the unit cell of YBa2Cu3O7 performed by Freeman, Massida and Yu were presented. Results of a detailed study of the pseudoternery phase diagram involving CuO, BaO and YO1.5 were shown which verify the existence of three compounds having the Y:Ba:Cu ratios 123 (the high Tc superconductor), 211 (the so-called green phase) and 132 (a new insulating compound). This work, performed by Mason and coworkers, involved X-ray diffraction, optical spectroscopy, magnetic susceptibility, and electrical transport studies. Transport measurements by Poeppelmeier, Song, Hwu and coworkers on the assembledges YBaSrCu3O7 anf YBa2Cu3O5F2 were reported; no evidence of superconducting behavior at temperatures above 90K was seen in the latter. A detailed study of the magnetic and transport properties of the YBa2-xLaxCu3-xNixO7±? system was reported. For small Ni concentration (x<0.3) a continuous drop in Tc was observed. For x= 0.4 and 0.5 evidence of two separate transitions, near 75K and 25K, were seen in the resistance (with the resistance going to zero at about 15K); for x=0.7 semiconducting behavior was observed. A continuous drop in the normalized diamagnetic signal was seen with increasing x with the diamagnetic fraction being below 5 % for x=0.7 and above. X-ray diffraction showed a continuous decrease in the orthorhombic fraction and an increase in the tetragonal fraction with increasing x. Results on d.c. magnetron sputtering of thin films on MgO from a stoichiometric 123 target in an argon atmosphere were shown. With proper annealing films with onset temperature of 90K and zero resistance at 68K have been prepared; this work was done by Jin, Lee, Song and coworkers. A brief report on the effect of O-stoichiometry on EPR and susceptibility measurements in the 123 compound performed by Hoffman and coworkers and NMR in the La2-xSrxCuO4 compound by Halpern and coworkers was presented.

Ketterson, J. B.

97

Development of the Permian-Triassic unconformity in southwestern Utah, southeastern Nevada and northwestern Arizona  

SciTech Connect

Development of positive areas, that are oriented northwest-southeast in south-western Utah, southeastern Nevada, and northwestern Arizona, are indicated by the depositional patterns of the Rock Canyon Conglomerate and facies changes produced by on-lapping during the deposition of the Timpoweap, Lower Red, and Virgin Limestone Members of the Moenkopi Formation. The lack of facies change in the Kaibab Formation indicates that uplift of the positive areas did not start during the early Permian. The Fossil Mountain Member of the Kaibab Formation, is a marker of continuous shallow marine sedimentation across the area. The Harrisburg Member contains three limestone units, separated by gypsum and shale units, that represent regressions and transgressions. Where the gypsum in the Kaibab Formation thins, collapse breccia and deformed shale units are present indicating that the gypsum was deposited and then removed by dissolution. Channels cut during the late Permian and early Triassic Periods do not cut through the Harrisburg Member of the Kaibab Formation. West of St. George, Utah, where the gypsum deposits are thickest, is the location where Timpoweap, Lower Red, and Virgin Limestone members thin and are absent. Late Permian and early Triassic topography may have in part been controlled by dissolution of the gypsum deposits in the Kaibab Formation. The low angle of discordance between Permian and Triassic units indicated that the area was not subjected to major deformation during the late Permian and early Triassic, but was gently tilted and uplifted.

Nielson, R.L. (Stephen F. Austin State Univ., Nacogdoches, TX (United States). Dept. of Geology)

1993-04-01

98

Development and application of a drought index for Northwestern Nevada  

Microsoft Academic Search

A study of precipitation and temperature was conducted on the Northwestern climate section of Nevada to develop a drought index for the state. The index was based on data from an average of ten weather stations with 70 years or more of record to allow inclusion of a proven drought period during the years 1933 to 1935. The Palmer Drought

Barbara Lynn Blasey

1997-01-01

99

Late Pleistocene Glaciations in the Northwestern Sierra Nevada, California  

Microsoft Academic Search

Pleistocene fluvial landforms and riparian ecosystems in central California responded to climate changes in the Sierra Nevada, yet the glacial history of the western Sierra remains largely unknown. Three glacial stages in the northwestern Sierra Nevada are documented by field mapping and cosmogenic radionuclide surface-exposure (CRSE) ages. Two CRSE ages of erratic boulders on an isolated till above Bear Valley

L. Allan James; Jon Harbor; Derek Fabel; Dennis Dahms; David Elmore

2002-01-01

100

Late Cenozoic mesa basalt sheet in northwestern United States  

Microsoft Academic Search

Numerous occurrences of late Cenozoic (Late Pliocene or early Quaternary) diktytaxitic, olivine basalt in Oregon, northeastern\\u000a California, northwestern Nevada and southwestern Idaho are interpreted as remnants of a regionally extensive, thin basalt\\u000a sheet, manifesting a single volcanic event of vast magnitude.

H. E. Wheeler; H. A. Coombs

1967-01-01

101

Block Interactions in Southern Oregon, Northern California, and Northwestern Nevada  

Microsoft Academic Search

Southern Oregon, northern California, and northwestern Nevada is an area of plate tectonic interest due to the surrounding complex interactions between the Pacific plate, Sierra Nevada block, western Basin and Range, California Coast Range, Mendocino Transform, Juan de Fuca plate and the San Andreas fault. The overall net effects from these interactions on the tri-state area are unknown and constitute

J. J. Vollick; R. McCaffrey; G. Sella; C. Stevens; T. Williams; C. McCaffrey; B. Walton

2003-01-01

102

Shelf sandstones of Twowells tongue, Dakota Sandstone, northwestern New Mexico  

Microsoft Academic Search

The Dakota Sandstone of northwestern New Mexico is composed of basal continental strata and three marine sandstone tongues, which intertongue was the Mancos Shale. The late Cenomanian Twowells tongue was the last tongue deposited in the Dakota transgressive systems tract. This tongue is most commonly gradationallly underlain by the Whitewater Arroyo shale tongue and abruptly overlain by the Rio Salado

N. R. Wolter; D. Nummedal

1988-01-01

103

Novel Poxvirus in Big Brown Bats, Northwestern United States  

PubMed Central

A wildlife hospital and rehabilitation center in northwestern United States received several big brown bats with necrosuppurative osteomyelitis in multiple joints. Wing and joint tissues were positive by PCR for poxvirus. Thin-section electron microscopy showed poxvirus particles within A-type inclusions. Phylogenetic comparison supports establishment of a new genus of Poxviridae.

Nordhausen, Robert; Garner, Michael M.; Huckabee, John R.; Johnson, Steven; Wohrle, Ron D.; Davidson, Whitni B.; Wilkins, Kimberly; Li, Yu; Doty, Jeffrey B.; Gallardo-Romero, Nadia F.; Metcalfe, Maureen G.; Karem, Kevin L.; Damon, Inger K.; Carroll, Darin S.

2013-01-01

104

Novel poxvirus in big brown bats, northwestern United States.  

PubMed

A wildlife hospital and rehabilitation center in northwestern United States received several big brown bats with necrosuppurative osteomyelitis in multiple joints. Wing and joint tissues were positive by PCR for poxvirus. Thin-section electron microscopy showed poxvirus particles within A-type inclusions. Phylogenetic comparison supports establishment of a new genus of Poxviridae. PMID:23735421

Emerson, Ginny L; Nordhausen, Robert; Garner, Michael M; Huckabee, John R; Johnson, Steven; Wohrle, Ron D; Davidson, Whitni B; Wilkins, Kimberly; Li, Yu; Doty, Jeffrey B; Gallardo-Romero, Nadia F; Metcalfe, Maureen G; Karem, Kevin L; Damon, Inger K; Carroll, Darin S

2013-06-01

105

The Center for Talent Development at Northwestern University  

ERIC Educational Resources Information Center

During the summer and on weekends, it is not unusual to see many children, the youngest holding their parents' hands, walking to classes amongst the beautiful landscaping and old buildings of Northwestern University on Lake Michigan's shores in Evanston, Illinois. The Center for Talent Development (CTD) has been offering services and programs to…

Olszewski-Kubilius, Paula

2004-01-01

106

Natural gases in mercury deposits of Donbass and Northwestern Caucasus  

SciTech Connect

A short review of information on the composition and genesis of natural gases in the Northwestern Caucasus and Donbass mercury deposits is presented. These differences in gas composition, as well as the distinct predominance of carbon dioxide and hydrogen in hydrothermally altered rocks, may be used for predicting gas-bearing capacity of deposits and for mercury prospecting in new areas. (JMT)

Fridman, A.I.; Makhlova, N.K.; Plotnikov, I.A.

1981-02-01

107

Unknown Strong Earthquakes In North-western Caucasus In Holocen  

Microsoft Academic Search

Studies and mapping on terrain seismo genic areas and determination of their modern seismic potential for the territory of the North-Western (Russian) Caucasus were fulfilled. The seismotectonic study of geological structures: faults, folds and blocks of the Earth's crust and allocation on this base of potential seismic sources of expected earthquakes (PSSs) was conducted. Fulfilled in the region investigations have

E. Rogozhin

2002-01-01

108

8. BUILDING 332, INTERIOR, HALLWAY NEAR MAIN ENTRANCE IN NORTHWESTERN ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

8. BUILDING 332, INTERIOR, HALLWAY NEAR MAIN ENTRANCE IN NORTHWESTERN PORTION OF BUILDING, LOOKING NORTH, WITH LOBBY TO LEFT AND CONFERENCE ROOM TO RIGHT. - Oakland Naval Supply Center, Dry Provisions Storehouses, Between Third & Fourth Streets, Between G & L Street, Oakland, Alameda County, CA

109

Precipitation and Streamflow Variability in Northwestern Oklahoma, 1894-2003  

Microsoft Academic Search

This paper utilizes time-series analysis to examine precipitation and stream- flow variability in northwestern Oklahoma over the period 1894-2003. Trends and periodicities in the hydroclimatic variables were investigated using, respectively, Mann- Kendall test and continuous wavelet transform (CWT) methods. Statistically significant trends were found in annual precipitation at individual gauging stations but with no spatial coherence to suggest evidence of

Joseph T. Zume; Aondover Tarhule

2006-01-01

110

Effect of the Spanish Conquest on coastal change in Northwestern Peru.  

PubMed

When Francisco Pizarro and his small band of Spanish conquistadores landed in northern Peru in A.D. 1532 to begin their conquest of the vast Inca Empire, they initiated profound changes in the culture, language, technology, economics, and demography of western South America. They also altered anthropogenically modulated processes of shoreline change that had functioned for millennia. Beginning with the extirpation of local cultures as a result of the Spanish Conquest, and continuing through today, the intersection of demography, economy, and El Niño-driven beach-ridge formation on the Chira beach-ridge plain of Northwestern Peru has changed the nature of coastal evolution in this region. A similar event may have occurred at about 2800 calibrated y B.P. in association with increased El Niño frequency. PMID:24843118

Belknap, Daniel F; Sandweiss, Daniel H

2014-06-01

111

Generalized Geologic evaluation of side looking radar imagery of the Teton Range and Jackson Hole, northwestern Wyoming  

NASA Technical Reports Server (NTRS)

A generalized geologic evaluation of lines, localities, and features of various types that are visible on a series of radar image strips covering the Teton Range and Jackson Hole in northwestern Wyoming, is given. No attempt was made to collate a complete geologic map with the radar image at each locality. Formation names, problems of geologic interpretation, and details of stratigraphy and structure that are not directly pertinent to a study of the imagery are omitted, but reference is made to publications that contain this type of supplementary information.

Love, J. D.

1970-01-01

112

The hydrocarbon potential, thermal maturity, sequence stratigraphic setting and depositional palaeoenvironment of carbonaceous shale and lignite successions of Panandhro, northwestern Kutch Basin, Gujarat, Western India  

Microsoft Academic Search

The objective of the present paper is to provide geochemical and palynological data to characterize lignites and carbonaceous\\u000a shales from Panandhro, northwestern Kutch Basin, Gujarat, Western India, in terms of their hydrocarbon potential, thermal\\u000a maturity, sequence stratigraphic settings and depositional palaeoenvironment. The samples, collected in Panandhro lignite\\u000a mine, belong to Naredi Formation of Late Paleocene-Early Eocene age. The geochemical results

Vinay K. Sahay

113

The hydrocarbon potential, thermal maturity, sequence stratigraphic setting and depositional palaeoenvironment of carbonaceous shale and lignite successions of Panandhro, northwestern Kutch Basin, Gujarat, Western India  

Microsoft Academic Search

The objective of the present paper is to provide geochemical and palynological data to characterize lignites and carbonaceous\\u000a shales from Panandhro, northwestern Kutch Basin, Gujarat, Western India, in terms of their hydrocarbon potential, thermal\\u000a maturity, sequence stratigraphic settings and depositional palaeoenvironment. The samples, collected in Panandhro lignite\\u000a mine, belong to Naredi Formation of Late Paleocene-Early Eocene age. The geochemical results

Vinay K. Sahay

2011-01-01

114

Seroprevalence of trichinellosis in domestic animals in northwestern Vietnam.  

PubMed

Trichinellosis is an important emerging or re-emerging zoonotic disease in Southeast Asia. In Vietnam, data on trichinellosis are scarce. Therefore, the present study was designed to determine the seroprevalence of trichinellosis in the domestic lifecycle in two provinces of northwestern Vietnam, where recently isolated outbreaks of human trichinellosis occurred. Serum samples were obtained from 558 pigs, 125 dogs and 98 cats, transported on filter paper, and tested for Trichinella antibodies by ELISA and Western blot, using larval excretory-secretory (E/S) antigens. The overall seroprevalence of antibodies to Trichinella was 5.6%, 4% and 0% in pigs, dogs and cats, respectively. In pigs, positive cases were distributed in 8/20 districts of the two provinces. This study suggests that Trichinella spp. is circulating in the domestic life cycle in northwestern Vietnam. Further study is recommended to investigate the presence of Trichinella in a sylvatic cycle, and to identify the occurring Trichinella species. PMID:23265187

Thi, N Vu; De, N V; Praet, N; Claes, L; Gabriël, S; Dorny, P

2013-03-31

115

Geology of the lower Yellow Creek Area, Northwestern Colorado  

SciTech Connect

The lower Yellow Creek area is located in Rio Blanco and Moffat Counties of northwestern Colorado, about midway between the towns of Rangely and Meeker. The study area is in the northwestern part of the Piceance Creek basin, a very deep structural and sedimentary basin that formed during the Laramide orogeny. Potentially important resources in the area are oil shale and related minerals, oil and gas, coal, and uranium. Topics discussed in the report include: Stratigraphy (Subsurface rocks, Cretaceous rocks, Tertiary rocks, and Quaternary deposits); Structure (Midland anticline, graben at Pinyon Ridge, and Crooked Wash syncline, Folds and faults in the vicinity of the White River, Red Wash syncline and central graben zone, Yellow Creek anticlinal nose); Economic geology (Oil shale and associated minerals, Coal, Oil and gas, Uranium, Gravel).

Hail, W.J.

1990-01-01

116

Geological mapping in northwestern Saudi Arabia using LANDSAT multispectral techniques  

NASA Technical Reports Server (NTRS)

Various computer enhancement and data extraction systems using LANDSAT data were assessed and used to complement a continuing geologic mapping program. Interactive digital classification techniques using both the parallel-piped and maximum-likelihood statistical approaches achieve very limited success in areas of highly dissected terrain. Computer enhanced imagery developed by color compositing stretched MSS ratio data was constructed for a test site in northwestern Saudi Arabia. Initial results indicate that several igneous and sedimentary rock types can be discriminated.

Blodget, H. W.; Brown, G. F.; Moik, J. G.

1975-01-01

117

41. SOUTHEAST ACROSS WOODWORKING SHOP AREA IN NORTHWESTERN QUADRANT OF ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

41. SOUTHEAST ACROSS WOODWORKING SHOP AREA IN NORTHWESTERN QUADRANT OF FACTORY SHOWING ON LEFT CIRCA 1900 CROSS-CUTOFF CIRCULAR SAW AND ON RIGHT CIRCA 1900 TABLE SAW. BEHIND THE CROSS-CUTOFF SAW IS A CIRCA 1900 SNAG GRINDER. IN THE CENTER BACKGROUND IS THE CIRCA 1900 MICHIGAN MACHINERY MFG. CO. PUNCH PRESS. - Kregel Windmill Company Factory, 1416 Central Avenue, Nebraska City, Otoe County, NE

118

Dynamics, Patterns and Causes of Fires in Northwestern Amazonia  

PubMed Central

According to recent studies, two widespread droughts occurred in the Amazon basin, one during 2005 and one during 2010. The drought increased the prevalence of climate-driven fires over most of the basin. Given the importance of human-atmosphere-vegetation interactions in tropical rainforests, these events have generated concerns over the vulnerability of this area to climate change. This paper focuses on one of the wettest areas of the basin, Northwestern Amazonia, where the interactions between the climate and fires are much weaker and where little is known about the anthropogenic drivers of fires. We have assessed the response of fires to climate over a ten-year period, and analysed the socio-economic and demographic determinants of fire occurrence. The patterns of fires and climate and their linkages in Northwestern Amazonia differ from the enhanced fire response to climate variation observed in the rest of Amazonia. The highest number of recorded fires in Northwestern Amazonia occurred in 2004 and 2007, and this did not coincide with the periods of extreme drought experienced in Amazonia in 2005 and 2010. Rather, during those years, Northwestern Amazonia experienced a relatively small numbers of fire hotspots. We have shown that fire occurrence correlated well with deforestation and was determined by anthropogenic drivers, mainly small-scale agriculture, cattle ranching (i.e., pastures) and active agricultural frontiers (including illegal crops). Thus, the particular climatic conditions for air convergence and rainfall created by proximity to the Andes, coupled with the presence of one of the most active colonisation fronts in the region, make this region differently affected by the general drought-induced fire patterns experienced by the rest of the Amazon. Moreover, the results suggest that, even in this wet region, humans are able to modify the frequency of fires and impact these historically well preserved forests.

Armenteras, Dolors; Retana, Javier

2012-01-01

119

Palaeontology and Zooarchaeology of Mezmaiskaya Cave (Northwestern Caucasus, Russia)  

Microsoft Academic Search

Over 6000 large mammal and numerous small vertebrate remains have been recovered from preliminary excavations at Mezmaiskaya Cave, situated at 1300–1350m above sea level in the northwestern foothills of the Caucasus Mountains. Most remains were recovered from layers containing Mousterian artefacts that date to the late Middle Pleniglacial (35,000bpand older). The faunal assemblage reflects a very low degree of weathering,

Robin L. Burgess

1996-01-01

120

Benthic fluxes of nutrients in the northwestern Black Sea  

Microsoft Academic Search

The exchange of O2, NH4+, Si(OH)4, ortho-phosphate, Fe2+, Mn2+ and H2S between the sediment and the overlying water (benthic flux) was determined at 6 locations on the northwestern shelf of the Black Sea using an in situ benthic lander. Oxygen consumption by the sediments ranged from 0 to 33 mmol m?2 d?1 depending mostly on the initial oxygen concentration in

Gabriela Friedl; Christian Dinkel; Bernhard Wehrli

1998-01-01

121

Northwestern University Facility for Clean Catalytic Process Research  

SciTech Connect

Northwestern University with DOE support created a Facility for Clean Catalytic Process Research. This facility is designed to further strengthen our already strong catalysis research capabilities and thus to address these National challenges. Thus, state-of-the art instrumentation and experimentation facility was commissioned to add far greater breadth, depth, and throughput to our ability to invent, test, and understand catalysts and catalytic processes, hence to improve them via knowledge-based design and evaluation approaches.

Marks, Tobin Jay [Northwestern University

2013-05-08

122

Deep crustal structure of northwestern Gulf of Mexico  

Microsoft Academic Search

The authors conducted a large-offset seismic experiment in the northwestern Gulf of Mexico, offshore Texas, using large-capacity air guns and ocean-bottom seismographs in order to map the salt-disrupted structure of the thickly sedimented shelf and slope. The authors shot five lines, each approximately 90 km long with four or more instruments, over an area extending from mid-shelf to the continental

Y. Nakamura; D. S. Sawyer; F. J. Shaub; K. MacKenzie; J. Oberst

1988-01-01

123

A southwest monsoon hydrographic climatology for the Northwestern Arabian Sea  

NASA Technical Reports Server (NTRS)

This paper provides a detailed hydrographic climatology for the shallow northwestern Arabian Sea prior to and during the southwest monsoon, presented as multiple-year composite vertical hydrographic sections based on National Oceanographic Data Center historical ocean station data. Temperature and salinity measurements are used to infer the water masses present in the upper 500 m. The hydrographic evolution depicted on bimonthly sections is inferred to result from wind-driven physical processes. In the northwestern Arabian Sea the water mass in the upper 50 m is the Arabian Sea Surface Water. Waters from 50 to 500 m are formed by mixing of Arabian Sea Surface Water with Antarctic and Indonesian intermediate waters. The inflow of Persian Gulf Water does not significantly influence the hydrography of the northwestern Arabian Sea along the Omani coast. Nitrate has a high inverse correlation with temperature and oxygen in the premonsoon thermocline in the depth interval 50-150 m. During the southwest monsoon, coastal upwelling off Oman and adjacent offshore upward Ekman pumping alter the shallow hydrography.

Brock, John C.; Mcclain, Charles R.; Hay, W. W.

1992-01-01

124

Late paleozoic tectonic amalgamation of northwestern China. Sedimentary record of the northern Tarim, northwestern Turpan, and southern Junggar basins  

SciTech Connect

This study focuses on areas adjacent to the Tian Shan (shan is Chinese for mountains) in Xinjiang Uygur Autonomous Region, northwestern China, and provides new field data on Carboniferous and Permian outcrop exposures of sedimentary rocks of the southern Junggar, northwestern Turpan, and northern Tarim basins that bear directly on the history of late Paleozoic tectonic amalgamation. We present here a multifaceted sedimentary basin analysis, including sedimentary facies, paleocurrent, and sandstone provenance analyses, and reconstructions of late Paleozoic basin subsidence. These data provide a unique record not only of the basins themselves, but also of the evolution of the adjacent orogenic belts. This study is based on fieldwork during the summers of 1987, 1988, 1991, and 1992 by workers from Stanford University, the Chinese Academy of Geological Sciences, and the Xinjiang Bureau of Geology and Mineral Resources. Although reconnaissance in nature, the data presented here provide a basis for evaluating alternative hypotheses for the evolution of northwestern China and provide a starting point for more comprehensive future studies. 72 refs., 18 figs., 1 tab.

Carroll, A.R. [Exxon Production Research Co., Houston, TX (United States); Graham, S.A.; Hendrix, M.S.; Ying, D.; Zhou, D. [Stanford Univ., CA (United States)

1995-05-01

125

76 FR 77214 - Hawaii Crustacean Fisheries; 2012 Northwestern Hawaiian Islands Lobster Harvest Guideline  

Federal Register 2010, 2011, 2012, 2013

...DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration RIN 0648-XA838 Hawaii Crustacean Fisheries; 2012 Northwestern Hawaiian Islands Lobster Harvest Guideline AGENCY: National Marine Fisheries Service...

2011-12-12

126

Digital data sets that describe aquifer characteristics of the Enid isolated terrace aquifer in northwestern Oklahoma  

USGS Publications Warehouse

ARC/INFO export and nonproprietary format files The data sets in this report include digitized aquifer boundaries and maps of hydraulic conductivity, recharge, and ground-water level elevation contours for the Enid isolated terrace aquifer in northwestern Oklahoma. The Enid isolated terrace aquifer covers approximately 82 square miles and supplies water for irrigation, domestic, municipal, and industrial use for the City of Enid and western Garfield County. The Quaternary-age Enid isolated terrace aquifer is composed of terrace deposits that consist of discontinuous layers of clay, sandy clay, sand, and gravel. The aquifer is unconfined and is bounded by the underlying Permian-age Hennessey Group on the east and the Cedar Hills Sandstone Formation of the Permian-age El Reno Group on the west. The Cedar Hills Sandstone Formation fills a channel beneath the thickest section of the Enid isolated terrace aquifer in the midwestern part of the aquifer. All of the data sets were digitized and created from information and maps in a ground-water modeling thesis and report of the Enid isolated terrace aquifer. The maps digitized were published at a scale of 1:62,500. Ground-water flow models are numerical representations that simplify and aggregate natural systems. Models are not unique; different combinations of aquifer characteristics may produce similar results. Therefore, values of hydraulic conductivity and recharge used in the model and presented in this data set are not precise, but are within a reasonable range when compared to independently collected data.

Becker, C. J. Runkle, D. L.; Rea, Alan

1997-01-01

127

Hydrogeologic factors affecting cavern morphology within rocks of Mississippian age in northwestern Arkansas  

SciTech Connect

Cavern development within rocks of Mississippian age in northwestern Arkansas is associated with two Pleistocene erosional features, the Boston Mountains Plateau and the Springfield Plateau. Each plateau is characterized by a distinct stratigraphic sequence with unique lithologies. Cavern morphology (both cross-sectional and planimetric) in each plateau is the result of the complex interaction of numerous hydrogeologic factors. Four of the most dominant factors which affect cavern morphology appear to be: (1) composition and continuity of the confining units; (2) percentage of noncarbonate components in rocks of the cavern-forming interval; (3) nature and distribution of ground-water recharge to the cavern-forming interval; and (4) nature and distribution of fractures within the cavern-forming interval. Network maze patterns typically develop in the Pitkin Limestone, the formation in which most caverns form beneath the Boston Mountains Plateau. The Pitkin, a bioclastic limestone, is confined above by siltstones of the Cane Hill member of the Hale Formation and below by shales of the Fayetteville Formation. The maze pattern indicates that these caverns probably were formed by dissolution of the rock matrix by diffuse recharge moving vertically through leaky confining units. Single rooms are the dominant cavern morphology in the chert-dominated Boone Formation of the Springfield Plateau. Where the concentration of chert is greater than 50 percent, the Boone lacks structural integrity and fails to develop well-integrated conduit networks. Point recharge features in outcrop areas of the Boone Formation are not visible in most of the Springfield Plateau because the insoluble residuum masks the upper bedrock surface. Where the Boone Formation is less than 7 meters thick, surface karst features are more prevalent.

Fanning, B.J. (Univ. of Arkansas, Fayetteville, AR (United States). Dept. of Geology); Brahana, J.V. (Univ. of Arkansas , Fayetteville, AR (United States). Geological Survey)

1993-02-01

128

77 FR 28619 - Notice of Public Meetings: Sierra Front-Northwestern Great Basin Resource Advisory Council, Nevada  

Federal Register 2010, 2011, 2012, 2013

...Meetings: Sierra Front-Northwestern Great Basin Resource Advisory Council, Nevada AGENCY: Bureau of Land...BLM) Sierra Front-Northwestern Great Basin Resource Advisory...will hold two meetings in Nevada in fiscal year 2012....

2012-05-15

129

78 FR 13374 - Notice of Public Meetings: Sierra Front-Northwestern Great Basin Resource Advisory Council, Nevada  

Federal Register 2010, 2011, 2012, 2013

...Meetings: Sierra Front-Northwestern Great Basin Resource Advisory Council, Nevada AGENCY: Bureau of Land...BLM) Sierra Front-Northwestern Great Basin Resource Advisory...will hold two meetings in Nevada in fiscal year 2013....

2013-02-27

130

Cross-shelf exchange in the northwestern Black Sea  

NASA Astrophysics Data System (ADS)

transports of water, heat, and salt between the northwestern shelf and deep interior of the Black Sea are investigated using a high-resolution three-dimensional primitive equation model. From April to August 2005, both onshore and offshore cross-shelf break transports in the top 20 m were 0.24 Sv on average, which is equivalent to the replacement of 60% of the volume of surface shelf waters (0-20 m) per month. Two main exchange mechanisms are studied: Ekman transport, and transport by mesoscale eddies and associated meanders of the Rim Current. The Ekman drift causes nearly uniform onshore or offshore flow over a large section of the shelf break, but it is confined to the upper layers. In contrast, eddies and meanders penetrate deep down to the bottom, but they are restricted laterally. During the strong wind events of 15-22 April and 1-4 July, some 0.66 × 1012 and 0.44 × 1012 m3 of water were removed from the northwestern shelf, respectively. In comparison, the single long-lived Sevastopol Eddy generated a much larger offshore transfer of 2.84 × 1012 m3 over the period 23 April to 30 June, which is equivalent to 102% of the volume of northwestern shelf waters. Over the study period, salt exchanges increased the average density of the shelf waters by 0.67 kg m-3 and reduced the density contrast between the shelf and deep sea, while lateral heat exchanges reduced the density of the shelf waters by 0.16 kg m-3 and sharpened the shelf break front.

Zhou, Feng; Shapiro, Georgy; Wobus, Fred

2014-04-01

131

Finite frequency tomography fort the northwestern Pacific region  

NASA Astrophysics Data System (ADS)

We constructed a new P-wave tomographic model of the whole mantle with a focus on the northwestern Pacific region using more than ten millions of travel time data. The subducted slabs in the northwestern Pacific region show a complicated morphology; the slabs subducted from the south Kurile, Japan, Izu-Bonin arcs tend to be trapped in the mantle transition region, while to the north beneath the north Kurile and to the south beneath Mariana the slabs tend to penetrate the 660-km seismic discontinuity. To understand the relationship between such different behaviors of the subducted slabs, broadband seismic networks in the western Pacific Ocean and in the Russian Far East were deployed along with the Stagnant Slab Project (Japan) from 2005 to 2007. We collected other broadband seismograms in the northwestern Pacific region including Japan, China and the islands in the region. We picked the onsets of the first arrivals on the unfiltered seismograms if possible. The background noise level of the broadband ocean bottom seismogram is, in general, high in the periods less than 5 second due to the microseisms (pressure variations on the ocean floor induced by ocean waves) and in the periods around 100sec due to the infragravity waves. However the noise level takes a minimum and is comparable to that of the land stations in the periods in between. Therefore we measured P-wave differential times between two stations by applying the band-pass filter at the corners 0.03 and 0.08 Hz. We also measured PP-P differential times on the broadband seismograms of the global stations in around 0.1Hz frequency band. Finite frequency kernels were calculated at the corresponding frequency band for these differential travel time data. The finite frequency effect was also taken into account for the handpicked and the ISC data by calculating finite frequency kernels at 2 Hz instead of the ray theory. Such treatment for the handpicked data helps to reduce the artificial structures in the less resolved regions when the tomographic model constructed from the high frequency handpicked data and the lower frequency differential traveltime data simultaneously. The resolution of the obtained model become much better along the northwestern Pacific trenches than our previous model. The transition between the slab stagnation and penetration along the Izu-Bonin to Mariana trenches are well resolved.

Obayashi, M.; Yoshimitsu, J.; Nolet, G.; Fukao, Y.; Shiobara, H.; Sugioka, H.; Kasahara, M.; Gao, Y.

2012-12-01

132

Climate Change and Neotectonic History of Northwestern China  

NASA Technical Reports Server (NTRS)

The progress, results and future plans for the following objectives are presented: (1) To compare the types, rates, and magnitudes of surficial modification processes that have operated in Northwest China and the Southwestern U.S.; (2) To quantify and understand the basis of the remote sensing signatures of these processes to allow extrapolation from field sites to regional maps and to allow comparisons between widely separated arid regions; (3) To use the resulting chronologies to help define the temporal and spatial distribution of continental climate changes; and (4) Determine the ages of movements on some of the active faults in Northwestern China.

Farr, Tom G.; Chadwick, Oliver; Evans, Diane; Gillespie, Alan; Peltzer, Gilles; Tapponnier, Paul

1996-01-01

133

40. NORTH ACROSS WOODWORKING AREA IN NORTHWESTERN QUADRANT OF FACTORY ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

40. NORTH ACROSS WOODWORKING AREA IN NORTHWESTERN QUADRANT OF FACTORY ACROSS STACKED LUMBER ON SAWHORSES TOWARD CIRCA 1900 THICKNESS PLANER, SHOP-MADE BELT GUARD, AND BELOW THE SKYLIGHT OVERHEAD LINE SHAFT, BELTS, AND PULLEYS. BEYOND THE LUMBER ON A WHEELED WORK STATION ARE CIRCA 1900 ROLLS FOR BENDING PROPER CURVATURE IN STEEL WINDMILL BLADES AND CIRCA 1900 BEADING MACHINE FOR FORMING CREASES IN THE EDGES OF SHEET METAL PARTS SUCH AS WHEEL BLADES. - Kregel Windmill Company Factory, 1416 Central Avenue, Nebraska City, Otoe County, NE

134

Spawning migration and intraspecies differentiation of pink salmon from northwestern Sakhalin waters  

Microsoft Academic Search

Pacific salmon fishery near the northwestern Sakhalin coast is based on fish spawning both in the island and continental rivers. Salmon fishery near the Sakhalin coast of Amur Estuary has significantly lost contact with the main salmon rivers of the region. Pink salmon is the most abundant salmon species of the region rivers. Biology of the northwestern Sakhalin pink salmon

Alexander N. Ivanov; Alexej Shershnev; Nina P. Kaplanova; Konstantin L. Pusankov; Lubov V. Ivanova; Ekaterina N. Pusankova

2002-01-01

135

Late Cenozoic tectonic activity and its significance in the Northern Junggar Basin, Northwestern China  

NASA Astrophysics Data System (ADS)

The Dingshan area located in the northern part of the Junggar Basin of northwestern China is a significant prospect area for sandstone-type uranium deposits in China, where mainly Cenozoic rocks were deposited. The Cenozoic strata can be divided into four units according to the prior data and our own field observation. Sedimentary studies indicate that most Cenozoic strata were deposited under a hot and arid climate in a continental environment. The sedimentary facies are alluvial-fan, meandering-fluvial, and fluvio-lacustrine. Field investigation and interpretation of satellite images suggest that Cenozoic tectonics in the area is characterized by reactivation of early deep-seated thrusts, resulting in extensional fractures and formation of many small depressions in the shallow crustal level. Measurement of joint orientations suggests that regional shortening direction trends in north-south in the middle Pleistocene as indicated by the ESR (Electronic Spin Resonance) age of 0.1-0.4 Ma obtained from fault gouge and gypsum deposits. A four-stage sedimentation-tectonic evolution model of the northern Junggar Basin during the Late Cenozoic can be established based on reconstruction of sedimentary filling processes and Cenozoic tectonic movements. We suggest that landform evolution and groundwater movement are controlled by active tectonics, indicating that Late Cenozoic tectonic activities may also play important roles in the formation of sandstone-type uranium deposits. Therefore, a new metallogenic model for sandstone-type uranium deposits is proposed.

Chen, Zhengle; Liu, Jian; Gong, Hongliang; Han, Fengbin; Briggs, Stephanie Marion; Zheng, Enjiu; Wang, Guo

2011-01-01

136

Contemporary radioecological state of the North-western Black Sea and the problems of environment conservation.  

PubMed

Review is devoted to the analysis of a radioecological situation in the North-western Black Sea and concerns the levels of contamination of the components of an ecosystem by the main artificial radioactive isotopes ((90)Sr, (137)Cs, (239,240)Pu). The long-term accumulation trends of these radionuclides were analyzed in components of the Black Sea ecosystem after the Chernobyl nuclear power plant accident. Zones that have an increased ability to accumulate these radioisotopes were revealed. The assessment of irradiation dose rates formed by (90)Sr, (137)Cs and (239,240)Pu in Black Sea hydrobionts was obtained. The strategy for biodiversity conservation and sustainable management of natural resources should include monitoring of the radioecological state of the marine ecosystems, and the formation of a complex of biogeochemical criteria for assessment of an ecological situation in the sea. This approach is important for marine protected areas, since it allows the formation of a basis for scientific and practical function. PMID:24461697

Tereshchenko, N N; Mirzoyeva, N Yu; Gulin, S B; Milchakova, N A

2014-04-15

137

Geomagnetic variation anomalies in north-western Italy  

NASA Astrophysics Data System (ADS)

A preliminary geomagnetic variation data analysis has been made in the Piedmont-Ligurian area in north-western Italy. Data were collected by means of two instruments: an Askania portable variograph and a LaCour fixed station operated in the Roburent geomagnetic observatory. The portable variograph has been moved to several locations in north-western Italy. Parkinson vectors were drawn for 8, 20 and 60 min respectively, considering bay-like events recorded at single stations. Fourier parameters and anomaly maps for 32 and 64 min have been obtained after selecting similar events in order to simulate a magnetometric array. Results show trends that suggest possible correlations with three main geological features of the investigated area: (1) a coast effect probably also related to the lithospheric thickness of the Ligurian Sea; (2) a possible highly conductive channel connected to the Alpine system that could be analogous to anomalous structures found in Europe; and (3) an effect of the lower crust being obducted in the Ivrea body and subducted in the Southern Alps.

Bozzo, Emanuele; Meloni, Antonio

1989-03-01

138

Spatial variability of snow physical properties across northwestern Greenland  

NASA Astrophysics Data System (ADS)

In the late spring and early summer of 2013, researchers on the SAGE (Sunlight Absorption on the Greenland ice sheet Experiment) Traverse, embarked on a 4000 km ground traverse across northwestern Greenland in an attempt to quantify spatial variability of snow chemistry, snow physical properties, and snow reflectance. The field team targeted sites first visited by Carl Benson during his series of traverses from 1952 to 1955 as part of his pioneering work to characterize the Greenland Ice Sheet. This route now represents a rapidly changing and variable area of Greenland, as the route passes through several of the ice sheet facies first delimited by Benson. Along the traverse, the SAGE field team made ground-based albedo measurements using a hand-held spectroradiometer and collected snow physical property samples to determine snow specific surface area (SSA) from shallow, 2m pits. In addition, snow density and stratigraphy were measured. Snow layers in the near-surface and at the previous season's melt layer were targeted for sampling. Here we present preliminary snow physical property results from the upper portion of the snow pits and relate these to surface albedo data collected over the route. Further measurements of snow properties in the 2012 melt layer will be analyzed to assess the potential role of snow chemical (see Dibb et al. for a discussion of chemical analysis) and physical property driven albedo feedbacks could have played in contributing to that event. Route of 2013 SAGE Traverse in northwestern Greenland.

Courville, Z.; Polashenski, C.; Dibb, J. E.; Domine, F.

2013-12-01

139

Prevalence of anemia in First Nations children of northwestern Ontario.  

PubMed Central

OBJECTIVE: To estimate the prevalence of anemia among First Nations children of northwestern Ontario. DESIGN: Retrospective review of all hemoglobin determinations between 1990 and 1992 in the Sioux Lookout Zone. SETTING: The Sioux Lookout Zone Hospital, a secondary care referral hospital for 28 remote First Nations communities in northwestern Ontario, affiliated with the University of Toronto's Sioux Lookout Program. PARTICIPANTS: All First Nations children age 3 to 60 months who had produced venipuncture or fingerprick blood samples between 1990 and 1992 (614 children had a total of 1223 hemoglobin determinations). MAIN OUTCOME MEASURES: Prevalence of anemia by age, sex, geographical location, and diagnosis. Anemia was defined as a hemoglobin value less than 110g/L. RESULTS: Prevalence of anemia peaked in the age range of 6 to 24 months with prevalence rates of 51.7% to 79.3%. Conditions most commonly associated with anemia were respiratory tract infections. Children living in communities in the western part of the Sioux Lookout Zone were 1.64 times more likely to have anemia (95% confidence interval 1.15, 2.35) than children in the other communities. CONCLUSIONS: Anemia appears to be a serious public health problem among preschool children in the Sioux Lookout Zone.

Whalen, E. A.; Caulfield, L. E.; Harris, S. B.

1997-01-01

140

Great Earthquakes and Tsunamis of the Northwestern Aceh Coast, Sumatra  

NASA Astrophysics Data System (ADS)

The 2004 Andaman Aceh earthquake occasioned coseismic coastal subsidence in the range of 0.5 to 2.0 m on the northwestern Aceh coast. This coastal lowland contains stratigraphic evidence of previous great earthquakes and tsunamis on the Sunda megathrust that affected the coastline for hundreds of kilometers. We focused our research at three coastal sites in northwestern Aceh province. We conclude that three subduction zone earthquakes occurred in the early to mid Holocene (4500-7000 years ago) with an average recurrence of approximately 1000 years during conditions of relative sea level rise. Detailed investigations of lithology and micro- and macrofossil assemblages reveal regionally extensive buried mangrove soils that were coseismically subsided during the earthquakes and abruptly overlain by thin sand deposits of tsunami origin. The sands are covered by a sequence of intertidal muds. Tsunami deposits are inconsistently preserved, whereas the coseismic signal from buried soils is ubiquitously preserved. There is no stratigraphic record of subsidence in the late Holocene (4500 years to present) along the same coastal reach. In this time interval, far field locations such as Sumatra record stable or falling relative sea levels, which precludes coastal weltand progradation that leads to preservation of buried soils. In this younger, late Holocene time interval, the search for unique depocenters that preserve tsunami deposits provides a promising, alternative approach to constructing a paleoseimic record for the Aceh portion of the Sunda subduction zone.

Kelsey, H. M.; Horton, B. P.; Rubin, C. M.; Daly, P.; Grand Pre, C.; Hawkes, A.; Daryono, M.; Ismail, N.

2011-12-01

141

Seismic anisotropy in the continental crust of northwestern Canada  

NASA Astrophysics Data System (ADS)

Most studies of the seismic structure of continental crust assume that the wave speeds are isotropic at seismic wavelengths. The ability to measure surface wave propagation speed from the cross-correlation of ambient seismic noise provides new opportunities to image the crust and uppermost mantle. We investigate radial anisotropy in the continental crust of northwestern Canada from group-velocity curves of Love and Rayleigh waves obtained from ambient-noise cross-correlation. We test the null hypothesis that the Love and Rayleigh group-speed curves can be simultaneously fit by an earth model containing isotropic seismic velocities throughout the crust. Group velocity is predicted for 200 000 one-dimensional earth models, which are generated by randomly varying the crustal shear velocity and radial anisotropy within a prescribed range. The goodness-of-fit of the predictions is assessed by comparison with two sets of observed dispersion curves that correspond to two tectonically distinct terranes: the Archean/early Proterozoic craton and the transition from craton to Cordillera. The majority of best-fitting models contain VSH > VSV (4-5 per cent) in the middle crust. The finding that the middle/lower crust is seismically anisotropic across a large swath of northwestern Canada, combined with recent observations of anisotropic crust in much of the western United States, suggests that anisotropy may be ubiquitous in the continental crust.

Dalton, Colleen A.; Gaherty, James B.

2013-04-01

142

New insights of the oceanic lithosphere revealed from seismic studies in the Northwestern Pacific  

NASA Astrophysics Data System (ADS)

JAMSTEC has been carried out active-source seismic studies in the Northwestern Pacific in order to reveal a formation and alternation processed of the oceanic lithosphere. From those data, we obtained new insights of the oceanic lithosphere. For example, P-wave and S-wave velocities become slower toward the subduction zone, and Vp/Vs ratio of the upper part of the oceanic crust is increased. We also identified lower crustal reflectors dipping to the paleo-ridge along an off-Kuril profile which is perpendicular to the magnetic anomaly. A spatial interval and dipping angle of those reflectors are remarkably uniform; i.e., 4-5 km interval and 25 degree. In addition, we found, from seismic data acquired off Kuril, significantly high velocity (8.6 km/s) and strong anisotropy (10%) in uppermost mantle immediately below Moho. Clear shear-wave splitting is also observed in the same data. Moreover, the P-wave velocity of the uppermost mantle seems to decrease toward the subduction zone as we observed in the upper crust. From those seismological observations, the seismological characters of the oceanic lithosphere in the northwestern Pacific are summarized as 1) reduction of the seismic velocity toward the trench, 2) the high velocity and strong anisotropy immediately blow Moho at the seaward of the outer rise and 3) the lower crustal dipping reflector immediately above the high velocity and strong anisotropy mantle. 1) can be interpreted as a result of alternation of the crust and mantle associated with bending the plate in the outer rise region; e.g., hydration of the crust and srepentinization of the mantle. 2) and 3) are interpreted to be related to a formation and deformation processed near the ridge. Based on 2) and 3), we propose a hypothetical model showing that a strong mantle flow immediately below moho horizontally drag the base of the curst and consequently the lower crustal reflectors were formed as riedel shear in the lower crust. This hypothetical model should be examined by geological and petrological observations.

Kodaira, S.; Fujie, G.; Yamashita, M.

2011-12-01

143

Regional setting of Niobrara Formation in Northern Great Plains  

Microsoft Academic Search

Natural gas is currently produced from the Upper Cretaceous Niobrara Formation in northeastern Colorado, northwestern Kansas, and several small fields in Nebraska. As a part of studies of low-permeability gas reservoirs in the northern Great Plains, the regional geologic setting of the Niobrara has been investigated in North Dakota, South Dakota, and Nebraska. Structural contours of the Ardmore Bentonite Bed

Shurr

1984-01-01

144

Stratigraphic Analysis of Upper Cretaceous Rocks in the Mahajanga Basin, Northwestern Madagascar: Implications for Ancient and Modern Faunas.  

PubMed

Upper Cretaceous strata of the Mahajanga Basin, northwestern Madagascar, yield some of the most significant and exquisitely preserved vertebrate fossils known from Gondwana. The sedimentology of these strata and their stratigraphic relations have been the focus of renewed geological investigations during the course of five expeditions since 1993. We here designate stratotypes and formalize the terrestrial Maevarano Formation, with three new members (Masorobe, Anembalemba, Miadana), and the overlying marine Berivotra Formation. The Maevarano Formation accumulated on a broad, semiarid alluvial plain bounded to the southeast by crystalline highlands and to the northwest by the Mozambique Channel. The Berivotra Formation was deposited in an open marine setting that evolved from a clastic- to a carbonate-dominated shelf, resulting in deposition of the overlying Betsiboka limestone of Danian age. New stratigraphic data clearly indicate that the Maevarano Formation correlates, at least in part, with the Maastrichtian Berivotra Formation, and this in turn indicates that the most fossiliferous portions of the Maevarano Formation are Maastrichtian in age, rather than Campanian as previously reported. This revised age for the Maevarano vertebrate assemblage indicates that it is approximately contemporaneous with the vertebrate fauna recovered from the Deccan basalt volcano-sedimentary sequence of India. The comparable age of these two faunas is significant because the faunas appear to be more similar to one another than either is to those from any other major Gondwanan landmass. The revised age of the Maevarano Formation, when considered in the light of our recent fossil discoveries, further indicates that the ancestral stocks of Madagascar's overwhelmingly endemic modern vertebrate fauna arrived on the island in post-Mesozoic times. The basal stocks of the modern vertebrate fauna are conspicuously absent in the Maevarano Formation. Finally, the revised age of the Maevarano Formation serves to expand our global perspective on the K/T event by clarifying the age of a diverse, and arguably the best preserved, sample of Gondwanan vertebrates from the terminal Cretaceous. PMID:10769157

Rogers; Hartman; Krause

2000-05-01

145

Geogenic sources of local arsenic enrichment in groundwater from northwestern Thuringia, Germany  

NASA Astrophysics Data System (ADS)

Aqueous fluids migrating in the Earth's crust interact with the host rocks and partially take up their geochemical signatures. Mineralization and sometimes geogenic contamination of the groundwater may be the consequence: The aquifer systems of the Lower Triassic Buntsandstein Formation, an important source of drinking water in north-western Thuringia, and the Rotliegend Formation are locally affected by elevated arsenic concentrations. Data from water wells locally show arsenic concentrations above the limit value for drinking water (10 ?g/L). The regional distribution as well as lack of secondary vein mineralizations or anthropogenic sources within this area point to a geogenic stratibound source of arsenic. The average concentration of the toxic, carcinogenic trace element arsenic in rocks of Phanerozoic rocks in Germany range from 5 to 12 ?g/g for different lithologies, being generally higher in Variscan rocks. However, it can be several times enriched in certain sedimentary lithologies such as pelites and even more so in coal beds. In our present study we investigate all sequences of the Buntsandstein and Rotliegend Formation with their different lithologies in order to identify the relevant carriers of arsenic. Geochemical analyses on samples from selected drill cores and outcrops show arsenic of >50 ?g/g especially in carbonaceous sediment sections as well as in primarily gray-green lacustrine clay stones. Elevated arsenic concentrations seem to be related to lithofacies of lacustrine origin in the Buntsandstein and carbonaceous sediment sections in the Rotliegend. Aim of the current study is now to identify the appropriate synsedimentary mineral phases that incorporate arsenic and to identify the processes and conditions under which arsenic is mobilized from these phases and transferred into the groundwater.

Abratis, Michael; Viereck, Lothar

2014-05-01

146

Geophysical interpretations of the Libby thrust belt, northwestern Montana  

USGS Publications Warehouse

Interpretations of gravity and aeromagnetic anomaly data, supplemented by results from two seismic reflection profiles and five magnetotelluric soundings, were used to study buried structure and lithology of the Libby thrust belt of northwestern Montana. The gravity anomaly data show a marked correlation with major structures. The Purcell anticlinorium and the Sylvanite anticline are very likely cored by stacks of thrust slices of dense crystalline basement rocks that account for the large gravity highs across these two structures. Gravity anomaly data for the Cabinet Mountains Wilderness show a string of four broad highs. The principal magnetic anomaly sources are igneous intrusive rocks, major fault zones, and magnetite-bearing sedimentary rocks of the Ravalli Group. The most important magnetic anomalies in the principal study area are five distinct positive anomalies associated with Cretaceous or younger cupolas and stocks.

Kleinkopf, M. Dean; with sections by Harrison, Jack Edward; Stanley, W. D.

1997-01-01

147

North Pacific warming and intense northwestern U.S. wildfires  

NASA Astrophysics Data System (ADS)

The tropical Pacific sea surface temperature (SST) anomalies such as La Nina have been an important predictor for wildfires in the southeastern and southwestern U.S. This study seeks seasonal predictors for wildfires in the northwestern U.S., a region with the most intense wildfires among various continental U.S. regions. Singular value decomposition and regression techniques are applied to summer wildfire and current and antecedent SST conditions during a period of 23 years. It is found that warming in the North Pacific is a major feature in the SST spatial pattern related to intense Northwest wildfires. The warming appeared in all the major wildfire events during the past two decades. The relation is statistically significant. The North Pacific SST, therefore, has potential to be a predictor for seasonal Northwest wildfires.

Liu, Yongqiang

2006-11-01

148

Hantavirus Infection in Humans and Rodents, Northwestern Argentina  

PubMed Central

We initiated a study to elucidate the ecology and epidemiology of hantavirus infections in northern Argentina. The northwestern hantavirus pulmonary syndrome (HPS)–endemic area of Argentina comprises Salta and Jujuy Provinces. Between 1997 and 2000, 30 HPS cases were diagnosed in Jujuy Province (population 512,329). Most patients had a mild clinical course, and the death rate (13.3%) was low. We performed a serologic and epidemiologic survey in residents of the area, in conjunction with a serologic study in rodents. The prevalence of hantavirus antibodies in the general human population was 6.5%, one of the highest reported in the literature. No evidence of interhuman transmission was found, and the high prevalence of hantavirus antibody seemed to be associated with the high infestation of rodents detected in domestic and peridomestic habitats.

Levis, Silvana; Calderon, Gladys; Ramirez, Josefina; Bravo, Daniel; Lozano, Elena; Ripoll, Carlos; St. Jeor, Stephen; Ksiazek, Thomas G.; Barquez, Ruben M.; Enria, Delia

2003-01-01

149

Intoxication of nontarget wildlife with rodenticides in northwestern Kansas.  

PubMed

The perception of prairie dogs (Cynomys spp.) both as a nuisance species and a keystone species presents a significant challenge to land, livestock, and wildlife managers. Anticoagulant and nonanticoagulant rodenticides are commonly employed to control prairie dog populations throughout their range. Chlorophacinone, and to a lesser extent zinc phosphide, are widely used in northwestern Kansas for controlling black-tailed prairie dog (Cynomys ludovicianus) populations. Although zinc phosphide poisoning of gallinaceous birds is not uncommon, there are few published accounts of nontarget chlorophacinone poisoning of wildlife. We report three mortality events involving nontarget rodenticide poisoning in several species, including wild turkeys (Meleagris gallopavo), a raccoon (Procyon lotor), and an American badger (Taxidea taxus). This includes the first documentation of chlorophacinone intoxication in wild turkeys and an American badger in the literature. The extent of nontarget poisoning in this area is currently unknown and warrants further investigation. PMID:21270011

Ruder, Mark G; Poppenga, Robert H; Bryan, John A; Bain, Matt; Pitman, Jim; Keel, M Kevin

2011-01-01

150

Floods of January 15-17, 1974, in Northwestern Montana  

USGS Publications Warehouse

Introduction Rain and snowmelt caused several streams in northwestern Montana to flood during January 15-17, 1974. The flooding was caused by a major rainstorm that extended from Montana through Idaho and Washington. The most damage occurred in the Kootenai River drainage, centering around the town of Libby. Also unusually high flows occurred on some streams in the Clark Fork basin. Throughout the area, ice jams contributed to much of the overbank flooding. Both the towns of Troy and Libby were partly flooded, but damage was greatest in and near Libby. Flood damage was estimated to be $4.9 million. No flood fatalities were listed. Most of the smaller streams equaled or exceeded a 50-year flood. A summary of flood stages and discharges for 24 sites in the Kootenai River drainage and 8 sites in the Clark Fork drainage is tabulated. A map shows the extent of flooding in the Libby area. (Woodard-USGS)

Johnson, M. V.; Omang, R. J.

1974-01-01

151

Sinking velocity of particulate radiocesium in the northwestern North Pacific  

NASA Astrophysics Data System (ADS)

particles (SP) were collected by time series sediment traps at two depths in the northwestern Pacific before and after the Fukushima Daiichi Nuclear Power Plant accident, and accident-derived particulate radiocesium was measured. Radiocesium (137Cs) was first detected at 500 m (4810 m) about 2 weeks (1 month) after the accident. 137Cs of SP collected over 1 year revealed that the time lag between two depths was larger than that for the first 137Cs detection (about 2 weeks). We estimated the transient sinking velocity (SV) from the cumulative temporal 137Cs flux and the time lags at the two depths. Although the SV of SP collected in very early period was large, the estimated SV of most particulate 137Cs (about 80%) was about 50 m d-1. Based on comparison of 137Cs concentration in total SP with that in SP without organic materials, we suspect that most of the 137Cs was likely incorporated into aluminosilicates.

Honda, Makio C.; Kawakami, Hajime

2014-06-01

152

Ankylosaur Remains from the Early Cretaceous (Valanginian) of Northwestern Germany  

PubMed Central

A fragmentary cervico-pectoral lateral spine and partial humerus of an ankylosaur from the Early Cretaceous (early Valanginian) of Gronau in Westfalen, northwestern Germany, are described. The spine shows closest morphological similarities to the characteristic cervical and pectoral spines of Hylaeosaurus armatus from the late Valanginian of England. An extensive comparison of distal humeri among thyreophoran dinosaurs supports systematic differences in the morphology of the distal condyli between Ankylosauria and Stegosauria and a referral of the Gronau specimen to the former. The humerus fragment indicates a rather small individual, probably in the size range of H. armatus, and both specimens are determined herein as ?Hylaeosaurus sp.. A short overview of other purported ankylosaur material from the Berriasian-Valanginian of northwest Germany shows that, aside from the material described herein, only tracks can be attributed to this clade with confidence at present.

Sachs, Sven; Hornung, Jahn J.

2013-01-01

153

Middle Pleistocene age of the Nome River glaciation, northwestern Alaska  

NASA Astrophysics Data System (ADS)

During the middle Pleistocene Nome River glaciation of northwestern Alaska, glaciers covered an area an order of magnitude more extensive than during any subsequent glacial intervals. The age of the Nome River glaciation is constrained by laser-fusion {40Ar }/{39Ar} analyses of basaltic lava that overlies Nome River drift at Minnie Creek, central Seward Peninsula, that average 470,000 ± 190,000 yr (±1?). Milligram-size subsamples of the lava were dated to identify and eliminate extraneous 40Ar enrichments that rendered the mean of conventional K?Ar dates on larger bulk samples of the same flow too old (700,000 ± 570,000 yr). While the {40Ar }/{39Ar} analyses provide a minimum limiting age for the Nome River glaciation, maximum ages are provided by a provisional K?Ar date on a basaltic lava flow that underlies the Nome River drift at nearby Lave Creek, by paleomagnetic determinations of the drift itself at and near the type locality, and by amino acid epimerization analysis of molluscan fossils from nearshore sediments of the Anvilian marine transgression that underlie Nome River drift on the coastal plain at Nome. Taken together, the new age data indicate that the glaciation took place between 580,000 and 280,000 yr ago. The altitude of the Anvilian deposits suggests that eustatic sea level during the Anvilian transgression rose at least as high as and probably higher than during the last interglacial transgression; by correlation with the marine oxygen-isotope record, the transgression probably dates to stage 11 at 410,000 yr, and the Nome River glaciation is younger still. Analyses of floor altitudes of presumed Nome River cirques indicate that the Nome River regional snowline depression was at least twice that of the maximum late Wisconsin. The cause of the enhanced snowline lowering appears to be related to greater availability of moisture in northwestern Alaska during the middle Pleistocene.

Kaufman, Darrell S.; Walter, Robert C.; Brigham-Grette, Julie; Hopkins, David M.

1991-11-01

154

Understanding the Rainfall Daily Climatology of Northwestern Mexico  

NASA Astrophysics Data System (ADS)

Maximum monthly precipitation (MMP) over northwestern Mexico is not concurrent because it occurs in different months from July through September. However, instead of occurring progressively from one month to the next as latitude increases, as it might be logic since rains move progressively from south to north as monsoon develops, MMP occurs in July in latitudes of Jalisco state, then MMP shifts to August more to the north in latitudes of Nayarit state and along the eastern coast of the Gulf of California, then it occurs in July in higher latitudes through the main axis of the Sierra Madre Occidental (SMO), and finally MMP shifts to September to the west in the California Peninsula. The maximum monthly streamflow occurs in a similar pattern as MMP does but one month later. When daily rainfall climatology of the region is calculated, i.e. the long-term mean per day from stations with more than 20 years of data between 1940 and 2004, it is possible to understand why the behavior of MMP occurs in a July-August-July pattern from south to north. Preliminary results indicate that at latitudes of Nayarit state normal frequent storms with abundant rains develop at the end of July and through the August. These rains sum to the rains that move from the south to the north, as monsoon develops increasing the volume of precipitations at those latitudes in August. To the east crossing the SMO through northwestern Zacatecas state maximum volume of precipitations also is observed in August. However, in higher latitudes it is not observed any increment of rains in August and consequently maximum volume of precipitations occurs in July. To understand the dynamics of the rains at the latitudes of Nayarit state it results necessary to investigate the source of these local rains and explain why the increase of precipitations in August is limited at those latitudes.

Brito-Castillo, L.

2007-05-01

155

Hydrologic effects of the Pymatuning earthquake on September 25, 1998, in northwestern Pennsylvania  

USGS Publications Warehouse

Within hours after the Pymatuning earthquake of September 25, 1998, in northwestern Pennsylvania, local residents reported wells becoming dry, wells beginning to flow, and the formation of new springs. About 120 household-supply wells reportedly went dry within 3 months after the earthquake. About 80 of these wells were on a ridge between Jamestown and Greenville, where water-level declines of as much as 100 feet were documented. Accompanying the decline in water levels beneath the ridge was an increase in water levels in valley wells of as much as 62 feet. One possible explanation of the observed hydrologic effects is that the earthquake increased the vertical hydraulic conductivity of shales beneath the ridge, which allowed ground water to drain from the hilltops. Computer simulations of ground-water flow beneath the ridge between Jamestown and Greenville indicate that increasing the vertical hydraulic conductivity of shale confining beds about 10 to 60 times from their pre-quake values could cause the general pattern of decreased water levels on hilltops and increased levels in valleys.

Fleeger, Gary M.; Goode, D. J.; Buckwalter, T. F.; Risser, D. W.

1999-01-01

156

Thermal maturity and source-rock potential in Northwestern Melville Island, Arctic Canada  

SciTech Connect

This paper reports that approximately 130 core and drillhole cuttings samples taken from the Palaeozoic and Mesozoic of northwestern Melville Island were examined using reflected-light microscopy and Rock-Eval pyrolysis. The Palaeozoic section is dominated by bitumen, and often numerous bitumen populations are identified based on morphology, texture, and optical properties. Bitumen reflectance increases with depth, following a trend almost parallel to vitrinite, an indication that it is primary and has been subjected to similar thermal stress. The upper Palaeozoic sediments are within the hydrocarbon generation zone but have limited potential, except for an algal-rich interval in the Permian Trold Fiord Formation. Overall, the study is important because it attempts to identify the source rocks in an area of Melville Island where no previous work has been reported on the hydrocarbon-generating potential of the sedimentary succession. In addition, the use of bitumen reflectance in lower Palaeozoic strata devoid of vitrinite is evaluated and the amount of eroded section is calculated based on the thermal maturity pattern of bitumen.

Gentzis, T. (Alberta Research Council, Coal Research Center Devon, One Oil Patch Drive, Devon, Alberta T0C 1E0 (CA)); Goodarzi, F. (Geological Survey of Canada, Calgary, AB (Canada))

1992-10-01

157

Field methods to evaluate effects of pesticides on wildlife of the northwestern United States  

USGS Publications Warehouse

Field .methods used to evaluate the impact of organochlorine and organophosphate pesticides on wildlife populations in the Pacific Northwest are reviewed. Five field studies, presented in a CASE HISTORY format, illustrate study designs .and thetypes of information collected. The pesticides investigated included DDT, heptachlor, endr1n, and famphur, and the species studied included the American kestrel (Falco sparverius), Canada goose (Branta canadensis}, black--crowned night-heron (Nycticorax nycticorac), and black-billed magpie (Pica pica). Wildlife biologists conducting field studies of pesticides encounter a variety of design and logistics problems. However, a number of procedures are now available to the researcher for field evaluations. The three principa1 types of insecticides (organochlorines (OC's), organophosphates (OP's) and carbamates (CB's) require different field approaches. In this paper, five field studies, conducted by my colleagues and me between 1974 and 1982, in the northwestern portion of the United States (Washington, Oregon, Idaho, and northern Nevada), are reviewed to illustrate procedures for evaluating the effects of these insecticides.on wildlife populations. Althought most OC pesticides were banned in the United States during the 1970's (.for review, see F1eming et al. 1983), we studied several OC applications, including the last major DDT spray project in 1974. Use of OP's and CB's increased during the 1970's and 1980s as the OC's were phased out.

Henny, C.J.

1987-01-01

158

New Circulation Features in the Northwestern Tropical Pacific Ocean from Profiling Float Measurements  

NASA Astrophysics Data System (ADS)

Ten SOLO-II profiling floats have were deployed in the northwestern tropical Pacific Ocean in August 2011 as part of the ONR's Origin of the Kuroshio and Mindanao Currents (OKMC) project. These floats have a 5-day repeat cycle and measure T/S profiles at a vertical resolution of 2-dbars. By combining the OKMC and Argo data, we observed two well-defined branches of the eastward-flowing subtropical countercurrent (STCC). These two branches, located respectively along 19.0N and 21.5N, are embedded within the westward-flowing North Equatorial Current (NEC) between 7N and 25N and above the 26.5 isopycnal surface. Below the unventilated 26.5 isopycnal layer, the circulation is dominated by three, eastward-flowing, zonal jets. Dubbed the North Equatorial Undercurrent Jets (NEUJ), these three subthermocline jets are quasi-stationary and persist approximately along 10N, 13N and 18N, respectively. In the presentation, we will discuss in detail the mean structure and formation mechanism of these newly-observed NEUJs.

Qiu, B.; Rudnick, D. L.; Chen, S.

2012-12-01

159

Investigation of Salt Loss from the Bonneville Salt Flats, Northwestern Utah  

USGS Publications Warehouse

The Bonneville Salt Flats study area is located in the western part of the Great Salt Lake Desert in northwestern Utah, about 110 miles west of Salt Lake City. The salt crust covers about 50 square miles, but the extent varies yearly as a result of salt being dissolved by the formation and movement of surface ponds during the winter and redeposited with the evaporation of these ponds during the summer. A decrease in thickness and extent of the salt crust on the Bonneville Salt Flats has been documented during 1960-88 (S. Brooks, Bureau of Land Management, written commun., 1989). Maximum salt-crust thickness was 7 feet in 1960 and 5.5 feet in 1988. No definitive data are available to identify and quantify the processes that cause salt loss. More than 55 million tons of salt are estimated to have been lost from the salt crust during the 28-year period. The Bureau of Land Management needs to know the causes of salt loss to make appropriate management decisions.

Mason, James L.; Kipp, Kenneth L., Jr

1997-01-01

160

Structure and chemistry in the northwestern condensation of the Serpens molecular cloud core  

NASA Technical Reports Server (NTRS)

We present single-dish and interferometric observations of gas and dust in the core of the Serpens molecular cloud, focusing on the northwestern condensation. Single-dish molecular line observations are used to probe the structure and chemistry of the condensation while high-resolution images of CS and CH30H are combined with continuum observations from lambda = 1.3 mm to lambda = 3.5 cm to study the subcondensations and overall distribution of dust. For the northwestern condensation, we derive a characteristic density of 3 x 10(exp 5)/ cu cm and an estimated total mass of approximately 70 solar mass. We find compact molecular emission associated with the far-infrared source S68 FIRS 1, and with a newly detected subcondensation named S68 N. Comparison of the large-and small-scale emission reveals that most of the material in the northwest condensation is not directly associated with these compact sources, suggesting a youthful age for this region. CO J = 1 approaches 0 observations indicate widespread outflow activity. However, no unique association of embedded objects with outflows is possible with our observations. The SiO emission is found to be extended with the overall emission centered about S68 FIRS 1; the offset of the peak emission from all of the known continuum sources and the coincidence between the blueshifted SiO emission and blueshifted high-velocity gas traced by CO and CS is consistent with formation of SiO in shocks. Derived abundances of CO and HCO(+) are consistent with quiescent and other star-forming regions while CS, HCN, and H2CO abundances indicate mild depletions within the condensation. Spectral energy distribution fits to S68 FIRS 1 indicate a modest luminosity (50-60 solar luminosity), implying that it is a low-mass (0.5-3 solar mass) young stellar object. Radio continuum observations of the triple source toward S68 FIRS 1 indicate that the lobe emission is varying on timescales less than or equal to 1 yr while the central component is relatively constant over approximately 14 yr. The nature of a newly detected compact emission region, S68 N, is less certain due to the absence of firm continuum detections; based on its low luminosity (less than 5 solar luminosity) and strong molecular emission, S68 N may be prestellar subcondensation of gas and dust.

Mcmullin, Joseph P.; Mundy, Lee G.; Wilking, Bruce A.; Hezel, T.; Blake, Geoff A.

1994-01-01

161

OH and HO 2 measurements in a forested region of north-western Greece  

NASA Astrophysics Data System (ADS)

Boundary layer concentrations of hydroxyl (OH) and hydroperoxyl (HO 2) radicals were measured at 1180 m elevation in a mountainous, forested region of north-western Greece during the AEROsols formation from BIogenic organic Carbon (AEROBIC) field campaign held in July-August 1997. In situ measurements of OH radicals were made by laser-induced fluorescence (LIF) at low pressure, exciting in the (0, 0) band of the A-X system at 308 nm. HO 2 radicals were monitored by chemical titration to OH upon the addition of NO, with subsequent detection by LIF. The instrument was calibrated regularly during the field campaign, and demonstrated a sensitivity towards OH and HO 2 of 5.2×10 5 and 2.4×10 6 molecule cm -3, respectively, for a signal integration period of 2.5 min and a signal-to-noise ratio of 1. Diurnal cycles of OH and HO 2 were measured on 10 days within a small clearing of a forest of Greek Fir ( Abies Borisi-Regis). In total 4165 OH data points and 1501 HO 2 data points were collected at 30 s intervals. Noon-time OH and HO 2 concentrations were between 4-12×10 6 and 0.4-9×10 8 molecule cm -3, respectively. The performance of the instrument is evaluated, and the data are interpreted in terms of correlations with controlling variables. A significant correlation ( r2=0.66) is observed between the OH concentration and the rate of photolysis of ozone, J(O 1D). However, OH persisted into the early evening when J(O 1D) had fallen to very low values, consistent with the modelling study presented in the following paper (Carslaw et al., 2001, OH and HO 2 radical chemistry in a forest region of north-western Greece. Atmospheric Environment 35, 4725-4737) that predicts a significant radical source from the ozonolysis of biogenic alkenes. Normalisation of the OH concentrations for variations in J(O 1D) revealed a bell-shaped dependence of OH upon NO x (NO+NO 2), which peaked at [NO x] ˜1.75 ppbv. The diurnal variation of HO 2 was found to be less correlated with J(O 1D) compared to OH.

Creasey, D. J.; Heard, D. E.; Lee, J. D.

162

Correlation of Glaciations: a Comparison of Northwestern North America and the South American Cordillera  

NASA Astrophysics Data System (ADS)

Northwest Canada is one of the relatively few regions of the world where ice sheets from mountains (valley glaciers) and plains (Laurentide Ice Sheet) coalesced. This also occurred to a minor degree in N.W. Siberia (Arctic Ice Sheet and northern Ural Mountain valley glaciers) while in southern Argentina and Chile large coalescing Piedmont glaciers (Patagonian Ice Sheet) radiated out to the east and west, reaching both the Atlantic and Pacific Oceans. For the most part, build up of continental and Cordilleran ice was coincident in northwestern North America, clearly reflecting the 100 ka Milankovitch cycles. The notable absence of ice from MIS 56 to 38 in both N.A. and S.A. coincides with the low amplitude del 18O values, and bridges the time span during which the transition from 40 ka to 100 ka cycles is seen in the marine isotope record. The Argentinean record, which is the most complete thus far, appears to indicate a record of glaciation which considerably precedes that of N.A. Records from 5-6 Ma in N.A. and S.A have some similarities but the Argentinean record indicates a much earlier initiation of glaciation, dating back as far as 7.5 Ma. Small local glacier occurrences are rare in the earlier N.A. record (e.g. Yakataga Formation, Alaska) but much more common in the Argentinean record, suggesting that Argentinean valley glaciers may have developed earlier in response to cooling associated with the presence of the Antarctic Ice Sheet and the associated northward outflow of cold water along S.A. coasts. In N.A. the major Cordilleran/Montane glacial events commenced immediately preceding the Gauss/Matuyama boundary (2.8-2.6 Ma) and increased in frequency and magnitude with the advance of time. At the time of the Gauss-Matuyama boundary the N.A. and S.A. records are nearly synchronous. Proceeding back in time from the mid-Pleistocene transition (MIS 38), periods of ice free conditions appear to have been more extensive. In southern Argentina the Cordilleran glacial record appears to be somewhat independent from the global ice volume record. The extensive nonglacial periods that are noted in both continents correspond to major periods of tectonic stability and regional denudation. In northwestern North America there are at least 5 and possibly as many as 7 levels of pedimentation documented. In S.A. this record of pedimentation is considerably more extensive.

Barendregt, R. W.; Duk-Rodkin, A.

2008-12-01

163

Use of Anticlines for Geologic Sequestration of Carbon Dioxide in a Saline Aquifer in Northwestern Taiwan  

NASA Astrophysics Data System (ADS)

In this study, migration of CO2 in a deep saline aquifer with anticlines under various injection schemes was numerically simulated using the ECO2N simulator. The hypothetical study site was selected at the Taoyuan Plateau near the second largest coal-fired power plant, Datan power plant (annual CO2 emission of 1.5 Mt/yr), in Northwestern Taiwan. A 15x15 km2 simulation domain, containing two sub-parallel east-northeast Hukou and Pingzhen anticlines, was discretized into unstructured grid with spatial refinement at the injection borehole. Kueichulin sandstone and Chinshui shale in the simulation domain were considered as the storage formation and the cap rock, respectively. It was assumed that no CO2 exists in the aquifer prior to injection, and that the aquifer has a hydrostatic pressure distribution and a constant salinity of 3%. All boundaries were assumed to be "open". Isothermal simulations with 1 Mt/yr injection rate and 20 years of injection period were considered. van Genuchten capillary pressure and Corey relative permeability were assumed for all rock formations. Simulation results indicated that pressure buildup characterized the CO2 migration into three different phases: drainage of brine, formation dry-out, and dissolution and gravity take-over . It was found that the worst leakage scenario occurs if a single injection borehole is placed along the anticline axis. In this case, rock formations near the anticline axis provide a leakage path such that CO2 ultimately leaks out of the upper boundary. On the other hand, CO2 can be safely sequestrated in the storage formation if the injection borehole was placed away from the anticline axis. This is because gas phase CO2 migrates along the counter dipping direction of the anticline as a result of buoyancy. More favorable scenarios were found if a multiple-borehole injection scheme was used. In such cases, not only pressure buildup was significantly mitigated but the amount of precipitated salt was reduced. If a five-borehole scheme was used, for example, pressure buildup and the amount of precipitated salt can be reduced by 20% and 90%, respectively. More interestingly, if injection borehole was placed midway between the two anticlines, buoyancy dominates the migration of CO2 such that most CO2 is accumulated under the apex of anticline. Therefore, it is suggested that a multiple-borehole injection scheme would be a preferable scenario because of the reduced risks of pressure buildup and salt precipitation. Moreover, it would be better to place the injection boreholes away from the anticline axis in order to make good use of all possible trapping mechanisms to permanently sequestrate CO2 in deep rock formations.

Lin, Shin-Hsun; Liou, Tai-Sheng

2013-04-01

164

Regional variability of factors controlling the onset timing and magnitude of spring algal blooms in the northwestern North Pacific  

NASA Astrophysics Data System (ADS)

Satellite imagery and oceanographic data collected between 2003 and 2009 were used to examine factors controlling the onset timing and magnitude of spring algal blooms in the northwestern North Pacific. Consistent with the critical depth hypothesis, the spring bloom onsets coincided with the mixed layer depth (MLD) shoaling in the north of the Kuroshio extension and in Oyashio, where complex frontal physical structures and turbulence weakening, respectively, would be responsible for the MLD shoaling. In contrast, in the formation regions of the dense central mode water (D-CMW) and the transition region mode water (TRMW), bloom onsets coincided with possible turbulence weakening but not with MLD shoaling. The peak of chlorophyll a in the formation regions of the D-CMW (0.44 ± 0.23 mg m-3) and the TRMW (0.58 ± 0.34 mg m-3) were ca. 5 times lower than that in the Oyashio (2.54 ± 0.74 mg m-3), despite the fact that nitrate concentration during the prebloom period was high (˜10 µM) and MLDs became shallow enough at the bloom peak in all the three regions. These observations indicated that light conditions and nitrate concentration did not explain the regional variability in the magnitude of spring blooms. The bloom magnitude west of ca. 150°E and in the north Kuroshio extension was increased relative to that in the eastern region, suggesting a chemical property in the water delivered from the Okhotsk Sea that would influence the western bloom. Our results demonstrated that factors controlling the timing and magnitude of spring algal blooms depend on the physicochemical regime in the northwestern North Pacific.

Shiozaki, Takuhei; Ito, Shin-Ichi; Takahashi, Kazutaka; Saito, Hiroaki; Nagata, Toshi; Furuya, Ken

2014-01-01

165

75 FR 53687 - Southern Montana Electric Generation & Transmission Cooperative, Inc. v. NorthWestern Corporation...  

Federal Register 2010, 2011, 2012, 2013

...Regulatory Commission [Docket No. EL10-82-000] Southern Montana Electric Generation & Transmission Cooperative, Inc. v. NorthWestern Corporation; Notice of Complaint August 25, 2010. Take notice that on August 20, 2010, pursuant to...

2010-09-01

166

78 FR 9327 - Hawaii Crustacean Fisheries; 2013 Northwestern Hawaiian Islands Lobster Harvest Guideline  

Federal Register 2010, 2011, 2012, 2013

...DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration 50 CFR Part 665 RIN 0648-XC453 Hawaii Crustacean Fisheries; 2013 Northwestern Hawaiian Islands Lobster Harvest Guideline AGENCY: National Marine Fisheries Service...

2013-02-08

167

76 FR 4551 - Hawaii Crustacean Fisheries; 2011 Northwestern Hawaiian Islands Lobster Harvest Guideline  

Federal Register 2010, 2011, 2012, 2013

...DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration 50 CFR Part 665 RIN 0648-XA159 Hawaii Crustacean Fisheries; 2011 Northwestern Hawaiian Islands Lobster Harvest Guideline AGENCY: National Marine Fisheries Service...

2011-01-26

168

75 FR 1597 - Western Pacific Crustacean Fisheries; 2010 Northwestern Hawaiian Islands Lobster Harvest Guideline  

Federal Register 2010, 2011, 2012, 2013

...Atmospheric Administration RIN 0648-XT33 Western Pacific Crustacean Fisheries; 2010 Northwestern Hawaiian Islands Lobster Harvest...lobster fishery is managed under the Fishery Management Plan for Crustacean Fisheries of the Western Pacific Region. The...

2010-01-12

169

Interim Summary: Nesting Counts of Ospreys and Brown Pelicans in Northwestern Mexico, 2006.  

National Technical Information Service (NTIS)

The distribution and abundance of nesting populations of California brown pelicans (Pelecanus occidentalis californicus) and ospreys (Pandion haliaetus) were documented in 2006 in northwestern Mexico. For ospreys only, the 2006 data were compared to popul...

C. J. Henny D. W. Anderson

2007-01-01

170

Evaluation of Heavy-Oil Potential of Northeastern Craig and Northwestern Ottawa Counties, Oklahoma.  

National Technical Information Service (NTIS)

This project was undertaken to evaluate the heavy-oil (oil less than 25 exp 0 API) potential of northeastern Oklahoma - specifically, northwestern Ottawa and northeastern Craig Counties, the area considered to have the best possibility for shallow, heavy-...

W. E. Harrison J. F. Roberts L. J. Heath

1979-01-01

171

NOTIS-3 (Northwestern On-Line Total Integrated System): Technical Services Applications.  

ERIC Educational Resources Information Center

Northwestern University Library's locally developed automated support system, NOTIS, operational since 1970-71, is described in terms of its technical services aspects. Internal applications and relevance to projected national networking developments are considered. (Author)

Horny, Karen L.

1978-01-01

172

Crustal structure of the northwestern Basin and Range Province and its transition to unextended volcanic plateaus  

Microsoft Academic Search

The northwestern margin of the Basin and Range Province is characterized by a transition from low-magnitude (?20%) extension in northwestern Nevada to relatively unextended volcanic plateaus in northeastern California. Seismic-velocity and potential-field modeling provides new control on the Mesozoic-to-present tectonic evolution of this poorly understood portion of the U.S. Cordillera. We document ?20% crustal thinning associated with Basin and Range

D. W. Lerch; S. L. Klemperer; J. M. G. Glen; D. A. Ponce; E. L. Miller; J. P. Colgan

2007-01-01

173

Crustal structure of the northwestern Basin and Range Province and its transition to unextended volcanic plateaus  

Microsoft Academic Search

The northwestern margin of the Basin and Range Province is characterized by a transition from low-magnitude (~20%) extension in northwestern Nevada to relatively unextended volcanic plateaus in northeastern California. Seismic-velocity and potential-field modeling provides new control on the Mesozoic-to-present tectonic evolution of this poorly understood portion of the U.S. Cordillera. We document ~20% crustal thinning associated with Basin and Range

D. W. Lerch; S. L. Klemperer; J. M. G. Glen; D. A. Ponce; E. L. Miller; J. P. Colgan

2007-01-01

174

Sulfur and iron speciation in surface sediments along the northwestern margin of the Black Sea  

Microsoft Academic Search

The speciation of sedimentary sulfur (pyrite, acid volatile sulfides (AVS), S0, H2S, and sulfate) was analyzed in surface sediments recovered at different water depths from the northwestern margin of the Black Sea. Additionally, dissolved and dithionite-extractable iron were quantified, and the sulfur isotope ratios in pyrite were measured. Sulfur and iron cycling in surface sediments of the northwestern part of

Jeroen W. M Wijsman; Jack J Middelburg; Peter M. J Herman; Michael E Böttcher; Carlo H. R Heip

2001-01-01

175

Tycoons and contraband: informal cross-border trade in West Nile, north-western Uganda  

Microsoft Academic Search

This article presents ethnographic evidence on the activities of the “tycoons” – large-scale cross-border contraband traders in north-western Uganda. It shows how engagement with state officials, but also integration in the broader community are two crucial aspects which explain the functioning of informal cross-border trade or “smuggling” in north-western Uganda. In doing so, it shows how, although there is a

Kristof Titeca

2012-01-01

176

Simulating the impacts of groundwater pumping on stream–aquifer dynamics in semiarid northwestern Oklahoma, USA  

Microsoft Academic Search

Visual MODFLOW, a numerical groundwater flow model, was used to evaluate the impacts of groundwater exploitation on streamflow\\u000a depletion in the Alluvium and Terrace aquifer of the Beaver-North Canadian River (BNCR) in northwestern Oklahoma, USA. Water\\u000a demand in semi-arid northwestern Oklahoma is projected to increase by 53% during the next five decades, driven primarily by\\u000a irrigation, public water supply, and

Joseph Zume; Aondover Tarhule

2008-01-01

177

Unknown Strong Earthquakes In North-western Caucasus In Holocen  

NASA Astrophysics Data System (ADS)

Studies and mapping on terrain seismo genic areas and determination of their modern seismic potential for the territory of the North-Western (Russian) Caucasus were fulfilled. The seismotectonic study of geological structures: faults, folds and blocks of the Earth's crust and allocation on this base of potential seismic sources of expected earthquakes (PSSs) was conducted. Fulfilled in the region investigations have allowed to study a structure of deforming ambiance's by compiling of 6 geophysical and structure-geological cross-sections and profiles, carried out given across stretching out folded systems. The important tectonic boundary between the Caucasus folded belt and the Transcaucasian microplate is studied on a south slope of The Main Caucasus Ridge. With the especial detailed where explored areas of largest faults in the region. On the south limb of the North-Western Caucasus near the above mentioned tectonic boundary the primary and secondary seismic ruptures of unknown ancient and known historical strong earthquakes (seismic faults, landslides, micrograbens) were discovered. Using an informative method of "trenching" enable to estimate a recurrence interval of seismic shocks in PSSs. The study of near surface structure of the faults in trenches to manage to define an absolute age of the seismic displacements, having place in Holocene on Malobzhid, Verkhnekhazar and Costal fault zones. Violated paleosoils have absolute age 990+- 100 years (IGAN 2126) for first fault and 520+-80 years (IGAN 2118) - for the second one. These seismic motions manages to identify with known, but referred to other seismic zone by strong earthquake Crimean-Kuban' region, 16 Septembers 1799. The seismic event magnitude was not less than 6.5, intensity - from 7 to 9. Determination of paleosoils and bones from the area of the Coastal fault absolute age denominated on surfaces in the manner of systems of escarps and gravitational- seismotectonic ruptures, has allowed to estimate periods of stability of the structure of 130+/-40, 6840+-30 years (IGAN-2417, 2418) and 2980+- 90 years (GIN-11728) ago. This signifies, that periods of activations of the structure, when colluvial and deluvial deposits accumulated, are correspondent at the time of near two -three thousand years and five thousand years ago. Thereby, the recurrence interval of strong earthquakes in the studied region is measured in 2 thousand years approximately.

Rogozhin, E.

178

Geochemistry and genesis of the banded iron formations of the Cauê Formation, Quadrilátero Ferrífero, Minas Gerais, Brazil  

Microsoft Academic Search

The Cauê Formation of the Paleoproterozoic Minas Supergroup hosts banded iron formations (BIFs), locally called itabirites, deposited in shallow marine passive margin settings. Two major compositional types of itabirite, dolomitic and quartz itabirites, are found in the northwestern part of QF. The former consists of alternating dolomite-rich and hematite-rich bands, whereas the latter is formed with alternating quartz-rich and hematite-rich

Carlos A. Spier; Sonia M. B. de Oliveira; Alcides N. Sial; Francisco J. Rios

2007-01-01

179

Northwestern University Schizophrenia Data and Software Tool (NUSDAST).  

PubMed

The schizophrenia research community has invested substantial resources on collecting, managing and sharing large neuroimaging datasets. As part of this effort, our group has collected high resolution magnetic resonance (MR) datasets from individuals with schizophrenia, their non-psychotic siblings, healthy controls and their siblings. This effort has resulted in a growing resource, the Northwestern University Schizophrenia Data and Software Tool (NUSDAST), an NIH-funded data sharing project to stimulate new research. This resource resides on XNAT Central, and it contains neuroimaging (MR scans, landmarks and surface maps for deep subcortical structures, and FreeSurfer cortical parcellation and measurement data), cognitive (cognitive domain scores for crystallized intelligence, working memory, episodic memory, and executive function), clinical (demographic, sibling relationship, SAPS and SANS psychopathology), and genetic (20 polymorphisms) data, collected from more than 450 subjects, most with 2-year longitudinal follow-up. A neuroimaging mapping, analysis and visualization software tool, CAWorks, is also part of this resource. Moreover, in making our existing neuroimaging data along with the associated meta-data and computational tools publically accessible, we have established a web-based information retrieval portal that allows the user to efficiently search the collection. This research-ready dataset meaningfully combines neuroimaging data with other relevant information, and it can be used to help facilitate advancing neuroimaging research. It is our hope that this effort will help to overcome some of the commonly recognized technical barriers in advancing neuroimaging research such as lack of local organization and standard descriptions. PMID:24223551

Wang, Lei; Kogan, Alex; Cobia, Derin; Alpert, Kathryn; Kolasny, Anthony; Miller, Michael I; Marcus, Daniel

2013-01-01

180

Geosites inventory of the northwestern Tabular Middle Atlas of Morocco  

NASA Astrophysics Data System (ADS)

Across the northwestern Tabular Middle Atlas of Morocco there are many examples of landscapes, rocks and fossils that provide key evidence of a particular moment or period in Earth history. Such Earth heritage sites are important for educating the general public in environmental matters. They also serve as tools for demonstrating sustainable development and for illustrating methods of site conservation as well as remembering that rocks, minerals, fossils, soils, landforms form an integral part of the natural world. The significance of certain sites for aesthetic or tourism reasons is obvious. There are numerous geosites, which could contribute to effective exploitation of geotourism, often in conjunction with ecotourism. The strategy employed to such sites involves close consultation with all communities in the vicinity of the respective geosite and is not only aimed at tourism and education, but also at sustainable improvement of the infrastructure of the people of this area. Geological heritage sites, properly managed, can generate employment and new economic activities, especially in regions in need of new or additional sources of income.

El Wartiti, Mohamed; Malaki, Amina; Zahraoui, Mohamed; El Ghannouchi, Abdelilah; di Gregorio, Felice

2008-07-01

181

Rangewide landscape genetics of an endemic Pacific northwestern salamander.  

PubMed

A species' genetic structure often varies in response to ecological and landscape processes that differ throughout the species' geographic range, yet landscape genetics studies are rarely spatially replicated. The Cope's giant salamander (Dicamptodon copei) is a neotenic, dispersal-limited amphibian with a restricted geographic range in the Pacific northwestern USA. We investigated which landscape factors affect D. copei gene flow in three regions spanning the species' range, which vary in climate, landcover and degree of anthropogenic disturbance. Least cost paths and Circuitscape resistance analyses revealed that gene flow patterns vary across the species' range, with unique combinations of landscape variables affecting gene flow in different regions. Populations in the northern coastal portions of the range had relatively high gene flow, largely facilitated by stream and river networks. Near the southeastern edge of the species' range, gene flow was more restricted overall, with relatively less facilitation by streams and more limitation by heat load index and fragmented forest cover. These results suggested that the landscape is more difficult for individuals to disperse through at the southeastern edge of the species' range, with terrestrial habitat desiccation factors becoming more limiting to gene flow. We suggest that caution be used when attempting to extrapolate landscape genetic models and conservation measures from one portion of a species' range to another. PMID:23293948

Trumbo, Daryl R; Spear, Stephen F; Baumsteiger, Jason; Storfer, Andrew

2013-03-01

182

Cancer surveillance in a remote Indian population in northwestern Ontario.  

PubMed

The incidence and mortality rates of malignant neoplasms in an isolated Indian population in northwestern Ontario, Canada during the period 1972-81 were determined and age-adjusted comparisons with the Canadian national population computed. Indian men were at half the risk of developing and dying from cancer compared to Canadian men, while among women the risks were similar. The most outstanding feature was the high mortality and incidence rates of kidney cancer in both sexes (relative risks for mortality and incidence 7 to 13 times that for Canadians). Gallbladder cancer was of importance in females, similar to observations in other Amerindian groups. Low-risk sites among Indians included: lung in men, breast in women, and skin in both sexes. Other sites such as colon and prostate were common in both populations. Establishing baseline incidence and mortality data and continuing surveillance over a period of time in a well-defined, geographically isolated Native population undergoing rapid social change is of interest both epidemiologically and from the health service perspective. Further studies may elucidate risk factors, of which diet appears most responsible for the peculiar pattern observed. PMID:6837814

Young, T K; Frank, J W

1983-05-01

183

Epiguruk: a late Quaternary environmental record from northwestern Alaska  

USGS Publications Warehouse

Epiguruk, a prominent bluff along the Kobuk River in northwestern Alaska, exposes a rich depositional record of Quaternary eolian and fluvial sand, with associated loess, paleosols, and periglacial features. Three major complexes of alluvial and eolian deposits are separated by two conspicuous organic-rich paleosols which formed during cool-moist interstadial intervals. Sediments between the two paleosols include eolian, channel, and floodplain deposits that formed during alluviation of the Kobuk River to a height of about 12m above the present level. The youngest depositional complex, which overlies the upper paleosol, is divisible into late Wisconsinan and Holocene components and into fluvial-channel, flood-plain, eolian-dune, sand-sheet, loess, and pond facies. Eolian sand from the active Kobuk sand sea overloaded the river during late Wisconsinan time, causing it to alluviate to about 13m above its modern level. The Holocene record reflects erosion and deposition by a small southern Tributary to the Kobuk River, downcutting by the Kobuk River toward its modern level, and subsequent erosion across a meander belt nearly 8km wide. 66 radiocarbon ages, many from rooted shrubs, provide a firm chronology for the past 35 k.y. at Epiguruk. -from Authors

Hamilton, T. D.; Ashley, G. M.

1993-01-01

184

Hydrogeologic framework of the Maku area basalts, northwestern Iran  

NASA Astrophysics Data System (ADS)

The Maku area in northwestern Iran is characterized by young lava flows which erupted from Mount Ararat in Turkey. These fractured volcanic rocks overlie alluvium associated with pre-existing rivers and form a good basalt-alluvium aquifer over an area of 650 km2. Groundwater discharge occurs from 12 large springs, ranging from 20 to 4,000 L s-1, and from some extraction wells. Permian and Oligo-Miocene age limestones along the northern boundary of the Bazargan and Poldasht Plains basalts are intensively karstified and groundwater from these high lands easily enters the basalt-alluvium aquifers. The transmissivity of the basalt-alluvium aquifer ranges from 24 to 870 m2 d-1, indicating heterogeneity. Groundwater of the aquifer is a sodium-bicarbonate and mixed cation-bicarbonate type and the concentration of fluoride is higher than the universal maximum admissible concentrations for drinking. In order to determine the chemical composition and identify the source of the high fluoride concentrations in the groundwater of the basaltic area, water samples from the springs, wells and rivers were analyzed. The results indicate that the high fluoride water enters the study area from the Sari Su River.

Asghari Moghaddam, Asghar; Fijani, Elham

2009-06-01

185

Quaternary shoreline development: the northwestern coast of Egypt  

NASA Astrophysics Data System (ADS)

New age estimates for samples representing different sedimentary units of the coastal ridges along El-Omayid-Burg El-Arab, northwestern coast of Egypt reveal that the Coastal (first) ridge is related to Holocene high sea level, aminozone "A", with evidence of recent (0.6±0.1 ka) ooid contributions. The El-Max-Abu Sir (second) ridge appears to be associated with the Last Interglacial and related to Oxygen Isotope Substages (OIS) 5c/5a. Beach boulders at the bottom of the Gebel Maryut (third) ridge are related to the Last Interglacial high-stand (OIS 5e), while the molluscan and Cardium limestones are related to a Cardium beach of lagoonal to shallow marine environment. This beach represents a coastal barrier, which existed between 208±59 to 292±48 ka, and is related to aminozones F-G and OIS 7-9. Complex paleosols are developed on the northern flanks of both the second and the third ridges with an estimate age of 67±31 ka and aminozone "C". These appear related to interstadial conditions at the early Last Glacial Stage. The paleosols (Pink limestone) at the top of the Khashm El-Ish (fourth) ridge show a wide range of ages, giving age estimates between 360±140 and 584±317 ka indicating a Middle Pleistocene age.

El-Asmar, Hesham M.; Wood, Philip

2000-07-01

186

Geophysical evidence of an impact crater in northwestern South America  

NASA Astrophysics Data System (ADS)

A prominent positive terrain correlated free-air gravity anomaly over regionally depressed topography may identify a mascon centered on (4.15 N, 69.5W) in the Vichada plain, Guiana Shield in Northwestern South America. The topographic depression was recognized by LANDSAT images, showing a complex crater with two rings of 30 km and 50 km of diameter. Being one third of the size of the Chibxulub's impact crater, the 50 km-wide impact crater is the first meteor impact found in Colombia and the biggest impact crater of South America. This structure has been partially eroded by the Vichada River and its topographic expression is obscured by dense vegetation and erosion. Free air gravity anomalies at 20 km altitude from EGM-96 do not show any significant signature. However, concentric positive terrain-correlated free-air gravity anomalies are superposed to the impact crater. Also negative Terrain decorrelated free air gravity anomalies are located at the impact crater structure. MOHO estimates from inverse modeled compensated terrain gravity effects show a shallower MOHO below the impact crater, with a thinning of the continental crust, that could be created as a result of the mantle rebound after the shock waves generated by the impact, creating a mascon, typical of an impact crater structure, with a 40 km-wide, 3 km-high plug of mantle material that had risen up into the Earth's crust. Concentric negative total field magnetic anomalies superposed to the gravity anomalies also support the impact crater model.

Hernandez, O.; von Frese, R. R.; Khurama, S.

2007-05-01

187

Survival of radiomarked canvasback ducklings in northwestern Minnesota  

USGS Publications Warehouse

Duckling survival, an important factor affecting annual recruitment, has not been determined adequately for canvasbacks (Aythya valisineria). We investigated the magnitude, timing, and causes of mortality of canvasback ducklings from hatch to fledging at the Agassiz National Wildlife Refuge (NWR) in northwestern Minnesota during 1987-90. During the 4 years, 217 day-old ducklings were radiomarked and released in 52 broods. Another 141 ducklings were radiomarked at 4 weeks of age. Survival was estimated with the Kaplan-Meier nonparametric estimator and the Weibull parametric model. Most mortalities occurred within 10 days after hatch. Total brood loss occurred in 18 (35%) of 52 broods released. The primary sources of mortality were predation, principally by mink (Mustela vison), and exposure to precipitation and cold temperature. For combined years, females had lower survival than males (P = 0.03). If the disparate survival between sexes of canvasbacks observed in this study is representative of canvasbacks in their breeding range, this phenomenon contributes to reduced reproductive potential and the male-biased sex ratio of the species.

Korschgen, C. E.; Kenow, K. P.; Green, W. L.; Johnson, D. H.

1996-01-01

188

Survival of radiomarked canvasback ducklings in northwestern Minnesota  

USGS Publications Warehouse

Duckling survival, an important factor affecting annual recruitment, has not been determined adequately for canvasbacks (Aythya valisineria). We investigated the magnitude, timing, and causes of mortality of canvasback ducklings from hatch to fledging at the Agassiz National Wildlife Refuge (NWR) in northwestern Minnesota during 1987-90. During the 4 years, 217 day-old ducklings were radiomarked and released in 52 broods. Another 141 ducklings were radiomarked at greater than or equal to 4weeks of age. Survival was estimated with the Kaplan-Meier nonparametric estimator and the Weibull parametric model. Most mortalities occurred within 10 days after hatch. Total brood loss occurred in 18 (85%) of 52 broods released. The primary sources of mortality were predation principally by mink (Mustela vison), and exposure to precipitation and cold temperature. For combined years, females had lower survival than males (P=0.03). If the disparate survival between sexes of canvasbacks observed in this study is representative of canvasbacks in their breeding range, this phenomenon contributes to reduced reproductive potential and the male-biased sex ratio of the species.

Korschgen, Carl E.; Kenow, Kevin P.; Green, William L.; Johnson, Douglas H.; Samuel, Michael D.; Sileo, Louis

1996-01-01

189

Northwestern University Schizophrenia Data and Software Tool (NUSDAST)  

PubMed Central

The schizophrenia research community has invested substantial resources on collecting, managing and sharing large neuroimaging datasets. As part of this effort, our group has collected high resolution magnetic resonance (MR) datasets from individuals with schizophrenia, their non-psychotic siblings, healthy controls and their siblings. This effort has resulted in a growing resource, the Northwestern University Schizophrenia Data and Software Tool (NUSDAST), an NIH-funded data sharing project to stimulate new research. This resource resides on XNAT Central, and it contains neuroimaging (MR scans, landmarks and surface maps for deep subcortical structures, and FreeSurfer cortical parcellation and measurement data), cognitive (cognitive domain scores for crystallized intelligence, working memory, episodic memory, and executive function), clinical (demographic, sibling relationship, SAPS and SANS psychopathology), and genetic (20 polymorphisms) data, collected from more than 450 subjects, most with 2-year longitudinal follow-up. A neuroimaging mapping, analysis and visualization software tool, CAWorks, is also part of this resource. Moreover, in making our existing neuroimaging data along with the associated meta-data and computational tools publically accessible, we have established a web-based information retrieval portal that allows the user to efficiently search the collection. This research-ready dataset meaningfully combines neuroimaging data with other relevant information, and it can be used to help facilitate advancing neuroimaging research. It is our hope that this effort will help to overcome some of the commonly recognized technical barriers in advancing neuroimaging research such as lack of local organization and standard descriptions.

Wang, Lei; Kogan, Alex; Cobia, Derin; Alpert, Kathryn; Kolasny, Anthony; Miller, Michael I.; Marcus, Daniel

2013-01-01

190

Basement structure of the north-western Yermak Plateau  

NASA Astrophysics Data System (ADS)

The separation of Northeast Greenland and Svalbard was achieved by large strike slip movements in Cenozoic times. Evidence for these movements can be found onshore both on North Greenland and Svalbard. However, the role of the Yermak Plateau in this process is quite speculative. New multichannel seismic (10 km spacing) and aeromagnetic data (7.5 km spacing) across the north-western part of the plateau show that the acoustic basement has a similar strike direction to that of the geological units onshore Svalbard. A prominent fault zone separates these most likely continental structures in the west from a more N-S extended transitional crustal block in the eastern part of the plateau. This part of the plateau is characterized by strong magnetic anomalies at least indicating highly intruded and stretched continental or even oceanic crust. However, the seismic data show that the plateau-like bathymetry is quite young. During most of its Cenozoic history the Yermak Plateau had a rough topography, similar to the topography onshore Svalbard. Thus, the paleo-bathymetry might have played an important role for the water exchange between the Arctic Ocean and the North Atlantic prior to the opening of the Fram Strait, which is today the main pathway for the deep-water masses.

Jokat, W.; Geissler, W.; Voss, M.

2008-03-01

191

Variability of suspended organic matter in the northwestern Black Sea  

NASA Astrophysics Data System (ADS)

The peculiarities in the distribution pattern of the concentration of suspended organic matter (SOM) components were studied for the long-term period of 1979-1995. We have analyzed their seasonal, annual, and interannual variability in the surface water layer and in the photosynthetic water layer in the northwestern Black Sea. Four areas pertaining to different concentrations of SOM components were defined according to the effect of riverine discharge and of open sea water masses, i.e. western, northern, central, and eastern areas. We have found an increase in the concentrations of SOM components in the summer-autumn period in the late 1980s and early 1990s, with the highest values observed in 1992. The concentration of suspended organic carbon was estimated for the concentration of Chlorophyll a in the surface water layer. These calculations are based on the regression relationship between simultaneous measurements of these two parameters in situ. It was found that the seasonal interannual variability in the concentrations of SOM components was affected by the volume of riverine discharge, its run to the sea, and climatic shifts.

Kukushkin, A. S.

2013-09-01

192

Drought induces spruce beetle (Dendroctonus rufipennis) outbreaks across northwestern Colorado.  

PubMed

This study examines influences of climate variability on spruce beetle (Dendroctonus rufipennis) outbreak across northwestern Colorado during the period 1650 2011 CE. Periods of broad-scale outbreak reconstructed using documentary records and tree rings were dated to 1843-1860, 1882-1889, 1931-1957, and 2004-2010. Periods of outbreak were compared with seasonal temperature, precipitation, vapor pressure deficit (VPD), the Palmer Drought Severity Index (PDSI), and indices of ocean-atmosphere oscillation that include the El Niño Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), and Atlantic Multidecadal Oscillation (AMO). Classification trees showed that outbreaks can be predicted most successfully from above average annual AMO values and above average summer VPD values, indicators of drought across Colorado. Notably, we find that spruce beetle outbreaks appear to be predicted best by interannual to multidecadal variability in drought, not by temperature alone. This finding may imply that spruce beetle outbreaks are triggered by decreases in host tree defenses, which are hypothesized to occur with drought stress. Given the persistence of the AMO, the shift to a positive AMO phase in the late 1990s is likely to promote continued spruce beetle disturbance. PMID:24933812

Hart, Sarah J; Veblen, Thomas T; Eisenhart, Karen S; Jarvis, Daniel; Kulakowski, Dominik

2014-04-01

193

Community Problems in Eight Northwestern Counties. Report No. 1 of a Series on Quality of Life and Development in Northwestern Wisconsin, January 1976.  

ERIC Educational Resources Information Center

As part of a study of the quality of life in northwestern Wisconsin, questions re: important problems, public services, and environmental concerns were asked of a sample of 150 people in each of 5 counties (Bayfield, Douglas, Price, Taylor, and Washburn) in 1974. Responses to similar questions asked in a 1973 study of Ashland, Burnett, and Rusk…

Lambert, Virginia

194

Brittle tectonics within the Jurassic formations of the Ouarsenis culminating area, northwestern Algeria  

NASA Astrophysics Data System (ADS)

Brittle structures within the Ouarsenis culminating zone were studied in order to characterize the polyphased tectonics. Field observations revealed that the dominant structures are highly tilted. They are represented by faults and joints, shears, reverse or curvilinear, locally associated with gypsum intrusions. Field data analysis shows that large scale shear faults are localized within the limits of the structural entities. Two main tectonic phases, having affected the Ouarsenis culminating zone were identified: (i) A NW-SE oriented compressive phase, represented by the contacts marked out by in-depth reverse faults and folding, mainly located in the westernmost part of Sra Abdelkader, Rokba Atba and in the western part of Batha, Fartas and Belkeiret (thrusts), respectively. This phase was also identified in reverse and sinistral faulting within Sidi Djber at the easternmost part of Sra Abdelkader, and the Grand Pic and the southern massif of Belkheiret respectively. (ii) A NNE-SSW oriented compressive phase, characterized by dextral strike-slips, is located in the easternmost part of Sra Abdelkader and Rokba Atba. North of the Grand Pic, a sinistral ?N120° oriented shearing occurred, with a lateral slip reaching ?2 km. The examination and the data analysis show a major N110-120° oriented fault with a sinistral signature. This movement would be responsible for block rotations and tilts. Counterclockwise rotations of the paleostress of ?38° and ?43° from west to east of the Sra Abdelkader massif and from Belkeiret to Batha, Fartas blocks were recorded, respectively. This local change of the stress field is mainly due to a deformation controlled by the regional post-Miocene geodynamic system, possibly explained by the proposed model.

Aïfa, Tahar; Zaagane, Mansour

2014-08-01

195

Radiolarian stratigraphy and origin of the Mesozoic terranes of the continental framework of the northwestern Pacific (Russia)  

NASA Astrophysics Data System (ADS)

Tectonostratigraphic investigation shows that the Mesozoic (Triassic-Neocomian) allochthonous terranes of the Anadyr-Koryak accretionary region, from the northwestern continental framing of the Pacific Ocean, form isolated tectonic nappes and slices dispersed all over the region, rather than fragments undeformed paleostructures. Nappes and slices of different stratigraphic horizons, derived from various geodynamic and paleolatitudinal environments, have been tectonically amalgamated into the Anadyr-Koryak region. Furthermore, these tectonostratigraphic units are accompanied by slabs of Paleozoic sequences which were also accumulated in various different paleoenvironments. Correlations of the tectonically separated Mesozoic formations are based on the radiolarians, and geochemical and lithologic methods. The tectonostratigraphic units range from Middle Triassic to Hauterivian, and are tectonically arranged in various spatial patterns. Formations of several different geodynamic environments are recognized: oceanic (abyssal plain and MOR), island arcs and marginal basins. The radiolarian assemblages suggest that the Early Mesozoic formations were deposited at different paleolatitudes: Tethyan (Anisian-Sinemurian), North-Tethyan and Boreal (Pliensbachian-Early Bajocian), and in a vast zone from the Equator to South Boreal (Late Bajocian-Hauterivian). Early to Late Mesozoic tectonic paleoenvironments spanned a width greater than 3000 km. This zone was later shortened to a width of 300 km. The development of nappes and slices of the Anadyr-Koryak region, and the Koryak-West Kamchatka orogenic belt on the whole, was due to several collisions near the Asian continental margin. The main collision event occurred in the interval 125-105 Ma.

Filatova, N. I.; Vishnevskaya, V. S.

1997-01-01

196

Paleostress pattern and salt tectonics within a developing foreland basin (north-western Subhercynian Basin, northern Germany)  

NASA Astrophysics Data System (ADS)

Analysing the paleostress field in sedimentary basins is important for understanding tectonic processes and the planning of drilling campaigns. The Subhercynian Basin of northern Germany is a perfect natural laboratory to study the paleostress field in a developing foreland basin. The simple layer-cake geometry of the basin-fill is dominated by several piercing and non-piercing salt structures. We derived the paleostress field from the orientation of fracture sets, faults, slickensides and stylolites. On a regional scale, the basin-fill is characterized by a horizontal compressional paleostress vector that is mainly NNE-SSW-oriented, which reflects the Late Cretaceous inversion phase in Central Europe. We show that the local paleostress field is distinctly perturbated due to the salt structures. Along the edge of the salt pillows, the maximum horizontal paleostress vector is deflected by up to 90° from the regional trend. In the case of the Elm salt pillow, it forms a radial pattern. Restoration of balanced cross-sections demonstrates at least 9 % of the shortening of the north-western part of the Subhercynian Basin was achieved by folding. The salt structures in the north-western Subhercynian Basin are the result of varying stress conditions. Initial extension in the Triassic caused first salt movements that prevailed during the Jurassic and Early Cretaceous. Most important is the Late Cretaceous contractional phase that shortened the diapirs and led to the formation of the salt pillows between diapirs due to detachment folding. We derive four main controlling factors for such salt-dominated contractional basins: (1) the wedge-shape basin-fill is the product of the dynamic load at the southern margin of the basin, (2) a basal salt layer fed the diapirs and acted as a detachment horizon during the later shortening, (3) detachment folding was the dominating deformation mechanism during contraction, and (4) the pre-existing diapirs controlled the position of the detachment folds.

Brandes, Christian; Schmidt, Carolin; Tanner, David Colin; Winsemann, Jutta

2013-11-01

197

Meteorologically-induced mesoscale variability of the North-western Alboran Sea (southern Spain) and related biological patterns  

NASA Astrophysics Data System (ADS)

Hydrographic mesoscale structures in the North-western Alboran Sea show a high variability induced by a number of different factors. One of the most important is the differences in atmospheric pressure over the Mediterranean basin when compared to the Gulf of Cádiz. This difference modulates the zonal wind field in the Alboran Sea and the intensity of the Atlantic inflow through the Strait of Gibraltar, also affecting the formation and extension of the Western Alboran Gyre (WAG). When westerly winds are dominant, lower atmospheric pressure in the Mediterranean enhances the inflow of Atlantic waters causing the Atlantic Jet to be located in the vicinity of the Spanish shore, creating a well-defined frontal zone in front of Estepona Cove. In this situation, the coastal upwelling is enhanced, leading to a minimum in sea surface temperature and a maximum of surface nutrient concentrations located in the coastal area. The vertical position of the chlorophyll maximum found in these circumstances appeared to be controlled by the nutrient availability. On the other hand, when easterly winds prevail, higher atmospheric pressure in the Mediterranean leads to a reduced inflow and the oceanographic and biological structures are clearly different. The Atlantic Jet moves southward flowing in a south-eastern direction, changing the structure of the currents, resulting in an enhanced cyclonic circulation extending throughout the North-western Alboran Sea basin. These physical alterations also induce changes in the distribution of biogeochemical variables. Maximum nutrient and chlorophyll concentrations are located further off the coast in the central area of the newly created cyclonic gyre. During these easterlies periods coastal upwelling stops and the distribution of phytoplankton cells seems to be mainly controlled by physical processes such as advection of coastal waters to the open sea.

Macías, D.; Bruno, M.; Echevarría, F.; Vázquez, A.; García, C. M.

2008-06-01

198

Evolutionary models of structural transfer zone in onshore and offshore areas, northwestern Taiwan  

NASA Astrophysics Data System (ADS)

Structural transfer zones in the frontal part of a fold-and-thrust belt mark the end of segments of major thrusts and represent the lateral variation in magnitude of displacement, slip direction and style of fault-related structure. On the other hand, in the frontal part of a fold-and-thrust belt of in-sequence and ongoing development, all fault-related structures represent the initial features of the following structural evolution. During the latest stage of the Penglai orogeny in northwestern Taiwan, two sets of fault system developed separately as a series of NW-SE fold-thrust belts and E-W high-angle thrusts. In this study, we demonstrate three evolutionary models of structural transfer zone during the initial stage of different thrust development, in-sequence development of thrust-related folding, interaction between normal fault reactivation and in-sequence development of thrusts, and normal fault reactivation resulting in the inversion structures. We use a grid of seismic profile and well bore data to interpret subsurface structural geometry, build a three-dimensional structural mode, and integrate trishear modeling to analyze the structural evolution. On the whole, three types of structural transfer zone can be identified based on their distinct development: 1. formation of the structural transfer zones in the inversion tectonic belt were controlled by the arrangement and linkage of early normal faults; 2. the continuity of fold geometry was first influenced by lateral variation in dip angle of low-angle thrust and in turn broken by high-angle transcurrent faulting, forming segmented fold structures during the late compression; and 3. slip along two parallel thrusts with opposite vergence and decreasing dip angle toward the transfer zone formed complex fault-related folds. The variation of P/S ratio along the strike of some thrusts also plays important role in shaping the features of the transfer zone.

Yang, Kenn Ming; Hsieh, Ching Yun; Iuan Chung, Bo; Ben Wang, Jar; Ting, Hsin Hsiu; Chuang, Hui Ju; Jie Lee, Chang

2014-05-01

199

Trace elements in moose (Alices alces) found dead in Northwestern Minnesota, USA  

USGS Publications Warehouse

The moose (Alces alces) population in bog and forest areas of Northwestern Minnesota has declined for more than 25 years, and more recently the decline is throughout Northwestern Minnesota. Both deficiencies and elevations in trace elements have been linked to the health of moose worldwide. The objective of this study was to evaluate whether trace element toxicity or deficiency may have contributed to the decline of moose in Northwestern Minnesota. Livers of 81 moose found dead in Northwestern Minnesota in 1998 and 1999 were analyzed for trace elements. With the exception of selenium (Se) and copper (Cu), trace elements were not at toxic or deficient levels based on criteria set for cattle. Selenium concentrations in moose livers based on criteria set for cattle were deficient in 3.7% of livers and at a chronic toxicity level in 16% of livers. Copper concentrations based on criteria set for cattle were deficient in 39.5% of livers, marginally deficient in 29.5% of livers and adequate in 31% of livers. Moose from agricultural areas had higher concentrations, on average, of Cd, Cu, Mo and Se in their livers than moose from bog and forest areas. Older moose had higher concentrations of Cd and Zn, and lower concentrations of Cu than younger moose. Copper deficiency, which has been associated with population declines of moose in Alaska and Sweden, may be a factor contributing to the decline of moose in Northwestern Minnesota. (C) 2004 Elsevier B.V. All rights reserved.

Custer, T. W.; Cox, E.; Gray, B.

2004-01-01

200

Serological and molecular prevalence of swine influenza virus on farms in northwestern Mexico.  

PubMed

The aim of this study was to provide an overview of the epidemiological status of swine influenza viruses in pigs from northwestern Mexico in 2008-2009. A serological and molecular survey was conducted in 150 pigs from 15 commercial farms in Sonora, Mexico (northwestern region of Mexico). The serological data showed that 55% of the sera were positive for the H1N1 subtype, 59% for the H3N2 subtype, and 38% for both subtypes. Overall, 16.6% (25/150) of the samples were positive for type A influenza by qRT-PCR. The phylogenetic analysis of the H1 viruses circulating in northwestern Mexico were grouped into cluster ?, from five other clusters previously described. The influenza virus H1 circulating in northwestern Mexico showed 97-100% identity at the nucleotide level among them, 89% identity with other North American strains, 88% with strains from central Mexico, and 85% with the pandemic A/H1N1p2009 virus. Meanwhile, a closer relationship with some influenza viruses from North America (97% nucleotide identity) was found for H3 subtype. In conclusion, our results demonstrated a high circulation of strains similar to those observed in the North American linage among commercial farms in northwestern Mexico, involving of a different lineage virus different to the influenza pandemic of 2009. PMID:24925324

López-Robles, Guadalupe; Montalvo-Corral, Maricela; Burgara-Estrella, Alexel; Hernández, Jesús

2014-08-01

201

Comparative phylogeography in marginal seas of the northwestern Pacific.  

PubMed

The maturation of marine phylogeography depends on integration of comparative information across different regions globally. The northwestern Pacific, characterized by unique tectonic setting, however, is still underrepresented. This study seeks to highlight its phylogeographical history based on the available population data, focusing on three seas: the East China Sea (ECS), the South China Sea (SCS) and the Sea of Japan (SOJ). We first conducted a literature survey to evaluate current research efforts and then reanalysed the population structure, historical demography and genealogy for two selections of studies (namely ‘the ECS category’ and ‘the multiple-sea category’) to elucidate the evolutionary processes within and across the seas, respectively. For the ECS category, the meta-analyses revealed most studies displayed a shallow phylogeny, indicating a single origin from the sea. Significant population structure was commonplace, particularly in molluck and crustacean studies, with proportions of 89% and 80%, respectively. Nearly all studies selected showed signals of population expansion: the times estimated were closely linked to a period of ~120-140 Kya rather than the last glacial maximum. For the latter category, divergent intraspecific lineages appeared among seas and overlapped in the adjacent regions, a pattern implying each sea had served as an independent refugium during glaciations. The genetic splits, however, were estimated to arise from separate events dating from late Miocene to middle Pleistocene. As phylogeography is still in its infancy in the region, more effort is needed to test and complement the general rules abstracted here. Finally, challenges and prospects were discussed to accelerate further research. PMID:24600706

Ni, Gang; Li, Qi; Kong, Lingfeng; Yu, Hong

2014-02-01

202

Benthic-Pelagic coupling in the Black Sea northwestern shelf  

NASA Astrophysics Data System (ADS)

A new approach for modeling the benthic compartment in 3D ocean models is applied to analyze the benthic-pelagic coupling in the Black Sea northwestern shelf (BS-NWS) and to review the contribution of sedimentary diagenesis to the BS-NWS biogeochemical cycles (nitrogen, oxygen and carbon). This approach combines an explicit representation of sediment organic matter deposition and resuspension, controlled by the bottom shear stress, and a parameterization of mineralization pathways control by bottom environmental properties. The model reproduces the magnitude and inter-regional and seasonal variability depicted by in situ benthic fluxes estimates obtained by benthic chambers and sediment cores incubations. The model illustrates how this observed variability results from both variable sedimentation rate and variable diagenetic pathways in the sediment layer. Three distinct areas are identified based on the analysis of the simulated seasonal cycle of bottom environmental conditions, benthic-pelagic fluxes and diagenetic processes. These areas extend along a gradient from the land-ocean interface to the open sea boundary and are each characterized by a particular diagenetic pathway, in a way similar as they succeed vertically in a sediment profile. (1) In the hypoxic zone, high remineralization rates lead to a seasonal peak in anoxic diagenesis and under certain conditions to hydrogen sulphide effluxes from the sediment, (2) in the denitrification zone, benthic denitrification rates are maximal and (3) in the oxic zone, where organic matter accumulation are low, oxic diagenesis prevails and seasonality is less marked. This study underlines that representing resuspension and deposition processes in coupled benthic-pelagic models is essential to realistically describe the horizontal distribution of benthic-pelagic fluxes and the export from the shelf region to the deep sea.

Capet, Arthur; Akoumianaki, Ionna; Meysman, Filip; Soetaert, Karline; Grégoire, Marilaure

2014-05-01

203

Mesozoic stratigraphy of northwestern Australian and northern Himalayan margins  

SciTech Connect

The Mesozoic stratigraphies of the Himalayan margin, the Argo abyssal plain, and the Exmouth Plateau exhibit marked contrasts in their sedimentation histories. The sedimentary sequence on the northeastern Exmouth Plateau off Australia includes a Carnian to Rhaetian sequence of fluviodeltaic and marine clastics and carbonates, capped by a shallowing-upward sequence of platform carbonates overlain, with a major unconformity, by marine Aptian sediments deposited during rapid subsidence of the plateau. Argo abyssal plain basement is overlain by red-brown, bioturbated, inoceramid-rich quartzose claystones, bentonites, and quartz siltstones, dated by radiolarians and benthic foraminifera as lowest Cretaceous. This is overlain by red and green claystones and nannofossil chalks. The basal age indicates that sea-floor spreading began in the earliest Cretaceous, not Oxfordian as had been thought. In the Thakkola region of Nepal, uppermost Triassic through Lower Jurassic shelf and carbonate platform facies are capped by a ferruginous oolite deposit of latest Bathonian to earliest Callovian age. Sedimentation resumed in the middle Oxfordian with deposition of Berriasian( ) deep-water black organic-rich mud. Following a valanginian regression and progradation of terrigenous clastics, Aptian black shales were deposited. In geological studies of the northwestern Australian margin, the ubiquitous hiatus within the Callovian-Oxfordian has been termed the breakup unconformity. Existence of a similar-aged hiatus in the Himalayas on a margin which formed during the late Paleozoic, absence of any Jurassic on the Exmouth Plateau, and the apparent initiation of spreading in the Argo basin during the earliest Cretaceous suggest that this widespread unconformity is not associated with a continental breakup in these regions.

Ogg, J.; Kopaskamerkel, D.C.

1989-03-01

204

A soil catena on schist in northwestern California  

USGS Publications Warehouse

Soil characteristics in a small steepland watershed underlain by schist in a rainy, tectonically active area in northwestern California show close associations with drainage-basin position and slope characteristics. Five soil-topography units based on these associations are defined in the study watershed. Spatial relationships of soil series, and patterns of soil development as indicated by B-horizon clay content and redness, reflect interactions between pedogenesis and erosion. General soil-topography patterns include: (1) decreases in soil-development moving from low-order to higher-order stream vallyes; and (2) more developed soils on north-facing as opposed to south-facing slopes. Decreases in soil-profile development moving from slopes near low-order streams to slopes near higher-order streams approximately correlate with increases in gradient, vertical relief, and drainage density, and reflect a more vigorous stripping of regolith by erosion on the slopes near the higher-order streams. The larger percentage of area covered by the more developed soils on north-facing as opposed to south-facing slopes appears to reflect a contrast in the way dominant erosional processes interact with pedogenic processes. Roadcuts on middle and upper slopes show soil discontinuities indicative of disturbance by block slides or slumps or both. Roadcuts on lower slopes show disrupted soils in small bedrock hollows that could have been created by rapid, shallow landslides or by the pulled-up root wads of toppled trees. Soil-profile characteristics and soil-topography patterns in the study area demonstrate that both erosional and pedogenic processes need to be considered when interpreting characteristics of hillslope soils. ?? 1986.

Marron, D. C.; Popenoe, J. H.

1986-01-01

205

Reclamation studies on oil shale lands in northwestern Colorado  

SciTech Connect

The overall objective of this project is to study the effects of various reclamation practices on above- and belowground ecosystem development associated with disturbed oil shale lands in northwestern Colorado. Plant growth media that are being used in field test plots include retorted shale, soil over retorted shale, subsoil materials, and surface disturbed topsoils. Some of the more significant results are: (1) a soil cover of at least 61 cm in conjunction with a capiallary barrier provided the best combination of treatments for the establishment of vegetation and a functional microbial community, (2) aboveground production values for native and introduced species mixtures are comparable after three growing seasons, (3) cover values for native species mixtures are generally greater than for introduced species, (4) native seed mixtures, in general, allow greater invasion to occur, (5) sewage sludge at relatively low rates appears to provide the most beneficial overall effect on plant growth, (6) cultural practices, such as irrigated and mulching have significant effects on both above- and belowground ecosystem development, (7) topsoil storage after 1.5 years does not appear to significantly affect general microbial activities but does reduce the mycorrhizal infection potential of the soil at shallow depths, (8) populations of mycorrhizal fungi are decreased on severely disturbed soils if a cover of vegetation is not established, (9) significant biological differences among ecotypes of important shrub species have been identified, (10) a vegetation model is outlined which upon completion will enable the reclamation specialist to predict the plant species combinations best adapted to specific reclamation sites, and (11) synthetic strains of two important grass species are close to development which will provide superior plant materials for reclamation in the West.

Cook, C.W.; Redente, E.F.

1980-02-01

206

Hydrogeochemistry and simulated solute transport, Piceance Basin, northwestern Colorado  

USGS Publications Warehouse

Oil-shale mining activities in Piceance basin in northwestern Colorado could adversely affect the ground- and surface-water quality in the basin. This study of the hydrology and geochemistry of the area used groundwater solute-transport-modeling techniques to investigate the possible impact of the mines on water quality. Maps of the extent and structure of the aquifer were prepared and show that a saturated thickness of 2,000 feet occurs in the northeast part of the basin. Ground-water recharge in the upland areas in the east, south, and west parts of the basin moves down into deeper zones in the aquifer and laterally to the discharge areas along Piceance and Yellow Creeks. The saline zone and the unsaturated zone provide the majority of the dissolved solids found in the ground water. Precipitation, ion-exchange, and oxidation-reduction reactions are also occurring in the aquifer. Model simulations of groundwater pumpage in tracts C-a and C-b indicate that the altered direction of groundwater movement near the pumped mines will cause an improvement in groundwater quality near the mines and a degradation of water quality downgradient from the tracts. Model simulations of mine leaching in tract C-a and C-b indicate that equal rates of mine leaching in the tracts will produce much different effects on the water quality in the basin. Tract C-a, by virtue of its remote location from perennial streams, will primarily degrade the groundwater quality over a large area to the northeast of the tract. Tract C-b, by contrast, will primarily degrade the surface-water quality in Piceance Creek, with only localized effects on the groundwater quality. (USGS)

Robson, Stanley G.; Saulnier, George J.

1980-01-01

207

Hydrogeochemistry and simulated solute transport, Piceance Basin, northwestern Colorado  

USGS Publications Warehouse

Oil-shale mining activities in Piceance basin in northwestern Colorado could adversely affect the ground- and surface-water quality in the basin. This study of the hydrology and geochemistry of the area used ground-water solute-transport-modeling techniques to investigate the possible impact of the mines on water quality. Maps of the extent and structure of the aquifer were prepared and show that a saturated thickness of 2,000 feet occurs in the northeast part of the basin. Ground-water recharge in the upland areas in the east, south, and west parts of the basin moves down into deeper zones in the aquifer and laterally to the discharge areas along Piceance and Yellow Creeks. The saline zone and the unsaturated zone provide the majority of the dissolved solids found in the ground water. Precipitation, ion-exchange, and oxidation-reduction reactions are also occuring in the aquifer. Model simulations of ground-water pumpage in tracts C-a and C-b indicate that the altered direction of ground-water movement near the pumped mines will cause an improvement in ground-water quality near the mines and a degradation of water quality downgradient from the tracts. Model simulations of mine leaching in tract C-a and C-b indicate that equal rates of mine leaching in the tracts will produce much different effects on the water quality in the basin. Tract C-a, by virtue of its remote location from perennial streams, will primarily degrade the ground-water quality over a large area to the northeast of the tract. Tract C-b, by contrast, will primarily degrade the surface-water quality in Piceance Creek, with only localized effects on the ground-water quality. (USGS)

Robson, S. G.; Saulnier, G. J., Jr.

1981-01-01

208

Strontium isotope dating of Upper Cenozoic marine deposits, northwestern Alaska  

SciTech Connect

High-precision Sr isotope measurements were obtained for 24 late Cenozoic molluskan shells from northwestern Alaska to test whether such data can be used to date arctic marine deposits. At present, the ages of geologic and climatologic events recorded by circum-arctic deposits older than the range of radiocarbon dating (>30 k.y.) are poorly known. Improving the chronological control would elucidate the interrelations between late Cenozoic global climate evolution and environmental changes in the Arctic, such as the inception of northern hemispheric ice sheets and perennial Arctic Ocean sea ice. Samples for this study were chosen from emerged and offshore marine deposits at Skull Cliff, Nome, and the Colville River area, where depositional ages are relatively well constrained on the basis of paleontologic, paleomagnetic, and amino acid criteria. At Skull Cliff, {sup 87}Sr/{sup 86}Sr ratios were measured in molluskan shells from five upper Pliocene to upper Pleistocene stratigraphic units composed of nearshore and inner shelf sediments. The {Delta}Sr values ({Delta}Sr = {sup 87}Sr/{sup 86}Sr{sub (sample)} {sup {minus}87}Sr/{sup 86}Sr{sub (standard)} {times} 10{sup 5}) range from 0.0 to {minus}7.2, and, except for the oldest unit decrease with increasing age. Four shells of two general collected from a single stratigraphic horizon over a distance of 100 m have indistinguishable {Delta}Sr values, within the range of external reproducibility ({plus minus}1{Delta}Sr), confirming an absence of vital effects. Sample ages for the upper three units at Skull Cliff, based on the comparison of the measured {Delta}Sr with the Sr isotope evolution of seawater recorded in independently dated deep-sea cores, agree broadly with the expected ages. The agreement suggests that the Arctic Ocean was in Sr isotope equilibrium with the world ocean during at least the past 1 m.y.

Kaufman, D.S.; Farmer, G.L.; Miller, G.H. (Univ. of Colorado, Boulder (USA)); Carter, L.D. (Geological Survey, Anchorage, AK (USA)); Brigham-Grette, J. (Univ. of Massachusetts, Amherst (USA))

1990-05-01

209

Seasonal thermocline in the China Seas and northwestern Pacific Ocean  

NASA Astrophysics Data System (ADS)

Climatological seasonal variations of the thermocline in the China Seas and northwestern Pacific Ocean were studied using historical data from 1930 through 2001 (707,624 profiles). The quantitative roles of surface thermal buoyancy (Bq), haline buoyancy flux (Bp), and total buoyancy flux (B) against the wind-induced mixing (?) in different seasons and regions were also explored using the buoyancy ratio (R = ?Bq/Bp?) and the Monin-Obukhov depth ratio (?), respectively. The thermocline has obvious seasonal variations in the study area north of 20°N. There is no thermocline along the west coast of the Bohai Sea (BS), Yellow Sea (YS), and northern East China Sea from December to March resulting from surface cooling and wind mixing. The significantly different variation of the thermocline strength on and off the Chinese shelf is mainly caused by the fact that the thermal stratification is enhanced by bottom tidal mixing on the shelf. The ? indicates that the thermocline depth on the Chinese shelf is mainly dominated by B in summer, while it is dominated by ? in winter. It reveals an opposite feature in the Kuroshio region; the dominating factor is B in winter, associated with the large heat buoyancy loss there. South of 20°N, the dominating factor is similar to that on the shelf, with the more obvious B dominant characteristic during the monsoon transition periods. The R demonstrates that B is mainly controlled by Bq all year round, with some sporadically Bp-dominated regions in the tropical area in winter and in the BS and eastern YS in September.

Hao, Jiajia; Chen, Yongli; Wang, Fan; Lin, Pengfei

2012-02-01

210

The Library as Leader: Computer Assisted Information Services at Northwestern University. A Report of the NULCAIS Committee on the Present Status, and Proposals for the Future, of Computer Assisted Information Services at Northwestern University Library.  

National Technical Information Service (NTIS)

In March 1974, a study was undertaken at Northwestern University to examine the role of the library in providing information services based on computerized data bases. After taking an inventory of existing data bases at Northwestern and in the greater Chi...

1974-01-01

211

Depositional And Diagenetic History Of Pliocene-Pleistocene Carbonates Of Northwestern Great Bahama Bank; Evolution Of A Carbonate Platform  

Microsoft Academic Search

Cores from nine borings across Northwestern Great Bahama Bank provide the basis for the first subsurface cross section across a Bahamian platform. This cross section reveals that through the Pliocene-Pleistocene the Northwestern Great Bahama Bank has been a dynamic evolving carbonate platform. Through this period, during episodes of sedimentation, there has been an overall trend toward shoaling water depths and

David Kent Beach

1982-01-01

212

The Northwestern Slope Valleys Region, Mars: A Prime Target for the Future Exploration of Mars  

NASA Astrophysics Data System (ADS)

Mars is a water-enriched planet theorized to have had Earth-like conditions during its embryonic stages of evolution (Early into Middle Noachian or > 3.8 GA). The Earth-like conditions include: (1) plate tectonism, (2) an active hydrosphere resulting in higher erosion rates and the presence of layered sedimentary deposits, and (3) a potential biosphere. Due to its smaller size and lower gravity, its thermal energy rapidly declined, sending the planet into a permanent monoplate regime. The Tharsis superplume, Elysium superplume, and structural discontinuities in the lithosphere are sites of long-lived energy releases and hydrothermal activity. Furthermore, as its atmosphere thinned and cooled, and water was lost to hydrodynamic escape, the Earth-like hydrological cycle transitioned into a persisting cold desert climate, approximating the present-day climate of the Dry Valleys in Antarctica. Stratigraphic, hydrogeomorphic, and paleotectonic information indicate an active Mars (e.g., late-stage superplume activity) that experienced punctuated periods of magmatic-driven hydrologic activity long after the Earth-like hydrologic regime had ended. Existing geologic, geomorphic, geophysical, topographic, impact cratering, spectral, and elemental information collectively point to a prime target site for future exploration that has the potential to yield significant geologic, paleoclimatic, paleohydrologic, and exobiologic information. The Northwestern Slope Valleys (NSVs) region archives traits similar to terrestrial field sites where the processes associated with: (1) fluvial, eolian, and hydrothermal activity, (2) modification due to landslides and glaciers, and (3) the formation of diverse rock assemblages (e.g., provenances include Noachian Thaumasia highlands mountain range and Europe-sized sedimentary basin and Noachian-Amazonian basaltic and possibly silica-enriched volcanoes and lava flow fields) are recorded. The region is especially remarkable since it encapsulates at least three distinct paleohydrologic regimes: Noachian-Early Hesperian NSVs flooding (~108 - 1010 m3/sec), Late Hesperian-Early Amazonian Mangala Valles flooding (~107 m3/sec), Amazonian sapping channel formation (~103 m3/sec), and recent groundwater seeps (<102 m3/sec), all of which expose deposits for in-situ study and sample return. Terrestrial analogs include: (1) Wet Beaver Creek, Arizona, which reveals intriguing geologic, hydrogeologic, and geomorphic similarities to a well-developed martian sapping channel, Abus Vallis, and (2) the Gray Mountain FIDO rover test site, which records diverse geological terrains similar to what might be encountered at the proposed NSVs prime target site.

Dohm, J. M.; Ferris, J. C.; Anderson, R. C.; Baker, V. R.; Hare, T. M.; Mahaney, W. C.

2002-12-01

213

The Talara Basin province of northwestern Peru: cretaceous-tertiary total petroleum system  

USGS Publications Warehouse

More than 1.68 billion barrels of oil (BBO) and 340 billion cubic feet of gas (BCFG) have been produced from the Cretaceous-Tertiary Total Petroleum System in the Talara Basin province, northwestern Peru. Oil and minor gas fields are concentrated in the onshore northern third of the province. Current production is primarily oil, but there is excellent potential for offshore gas resources, which is a mostly untapped resource because of the limited local market for gas and because there are few pipelines. Estimated mean recoverable resources from undiscovered fields in the basin are 1.71 billion barrels of oil (BBO), 4.79 trillion cubic feet of gas (TCFG), and 255 million barrels of natural gas liquids (NGL). Of this total resource, 15 percent has been allocated to onshore and 85 percent to offshore; volumes are 0.26 BBO and 0.72 TCFG onshore, and 1.45 BBO and 4.08 TCFG offshore. The mean estimate of numbers of undiscovered oil and gas fields is 83 and 27, respectively. Minimum size of fields that were used in this analysis is 1 million barrels of oil equivalent and (or) 6 BCFG. The Paleocene Talara forearc basin is superimposed on a larger, Mesozoic and pre-Mesozoic basin. Producing formations, ranging in age from Pennsylvanian to Oligocene, are mainly Upper Cretaceous through Oligocene sandstones of fluvial, deltaic, and nearshore to deep-marine depositional origins. The primary reservoirs and greatest potential for future development are Eocene sandstones that include turbidites of the Talara and Salinas Groups. Additional production and undiscovered resources exist within Upper Cretaceous, Paleocene, and Oligocene formations. Pennsylvanian Amotape quartzites may be productive where fractured. Trap types in this block-faulted basin are mainly structural or a combination of structure and stratigraphy. Primary reservoir seals are interbedded and overlying marine shales. Most fields produce from multiple reservoirs, and production is reported commingled. For this reason, and also because geochemical data on oils and source rocks is very limited, Tertiary and Cretaceous production is grouped into one total petroleum system. The most likely source rocks are Tertiary marine shales, but some of the Cretaceous marine shales are also probable source rocks, and these would represent separate total petroleum systems. Geochemical data on one oil sample from Pennsylvanian rock indicates that it was probably also sourced from Tertiary shales.

Higley, Debra K.

2004-01-01

214

Neotectonic and paleoseismicity studies on the Urumaco Fault, northern Falcón Basin, northwestern Venezuela  

NASA Astrophysics Data System (ADS)

The northern Falcón Basin in northwestern Venezuela is affected by several small active faults, subordinated to the major right-lateral east-west-trending Oca-Ancón Fault System. A set of prominent NW-SE right-lateral faults — synthetic shears — such as the Urumaco, R?´o Seco, Lagarto and La Soledad faults, stands out among those. The Urumaco Fault, located between the Lagarto and Mitare rivers (in the Urumaco Trough, west of Coro), presents a rather complex active fault trace that comprises two NW-SE fault segments linked by an ENE-WSW reverse echelon, all showing a restraining stepover geometry. Its western segment seems to continue to the north at sea. Conversely, the eastern one dies out on land and its northern tip ends in a transtensive horse-tail structure, that disrupts an Early Pleistocene conglomerate. This same unit is flexed and upheaved some 30 m at the restraining overlap. The kinematics and present stress tensor, the latest activity and the seismogenic potential of the eastern segment of the Urumaco Fault, have been assessed at a set of three river cuts of an ephemeral tributary stream of the Urumaco River, 3 km north of the Urumaco village, where the Urumaco Formation is truncated by a Late Pleistocene terrace ( 14C date of 20,700±950 yr BP at the base) of the Urumaco River. On the one hand, one of these outcrops features the Urumaco Fault affecting the Late Miocene Urumaco Formation, which comprises two prominent fault planes disposed as a wedge. The southwestern bounding plane juxtaposes two different sequences whereas the northeastern one does not, implying different slip behavior. In fact, the northeastern plane shows oblique-slip striations (29°N, normal-dextral), whereas the other one shows perfectly horizontal striations (right-lateral). On the other hand, both updip plane prolongations in the overlying alluvial unit are not so sharp, if the 17-cm throw of the erosive bottom of such terrace measured at the lowermost part of the southwestern plane is regarded as an artifact. However, a mudflat deposit within this unit is bent with a 14-cm throw right above the northeastern fault plane clearly affecting the underlying Miocene unit. The estimated total offset per event allows to infer the occurrence of two individual events of magnitude ranging between Ms 5.8 and 6.4 on this strand of the eastern segment of the Urumaco Fault in the last 20,000 yr.

Audemard, Franck A.; Bousquet, Jean-Claude; Rodr?´guez, José A.

1999-07-01

215

Pulsed remineralisation in the northwestern Mediterranean Sea: a hypothesis  

NASA Astrophysics Data System (ADS)

A general study of biogeochemical processes (DYNAPROC cruise) was conducted in May 1995 at a time-series station in the open northwestern Mediterranean Sea where horizontal advection was weak. Short-term variations of the vertical distributions of pico- and nanophytoplankton were investigated over four 36-h cycles, along with parallel determinations of metabolic CO 2 production rates and amino acid-containing colloid (AACC) concentrations at the chlorophyll maximum depth. The vertical (0-1000-m depth) distributions of (i) AACC, (ii) suspended particles and (iii) metabolic CO 2 production rate were documented during the initial and final stages of these 36-h cycles. This study was concerned with diel vertical migration (DVM) of zooplankton, which provided periodic perturbations. Accordingly, the time scale of the experimental work varied from a few hours to a few days. Although all distributions exhibited a periodic behaviour, AACC distributions were generally not linked to diel vertical migrations. In the subsurface layer, Synechococcus made the most abundant population and large variations in concentration were observed both at day and at night. The corresponding integrated (over the upper 90 m) losses of Synechococcus during one night pointed to a potential source of exported organic matter amounting to 534 mg C m -2. This study stresses the potential importance of organic matter export from the euphotic zone through the daily grazing activity of vertically migrating organisms, which would not be accounted for by measurements at longer time scales. The metabolic CO 2 production exhibited a peak of activity below 500 m that was shifted downward, apparently in a recurrent way and independently of the vertical distributions of AACC or of suspended particulate material. To account for this phenomenon, a «sustained wave train» hypothesis is proposed that combines the effect of the diel superficial faecal pellet production by swarming migrators and the repackaging activity of the nonmigrating midwater populations. Our results confirm the recent finding that the particulate compartment is not the major source of the observed instantaneous remineralisation rate and shed a new light on the fate of organic matter in the aphotic zone.

Denis, Michel; Martin, Valérie; Momzikoff, André; Gondry, Geneviève; Stemmann, Lars; Demers, Serge; Gorsky, Gaby; Andersen, Valérie

2003-02-01

216

Evaluation of slab images in the northwestern Pacific  

NASA Astrophysics Data System (ADS)

Recent P wave travel-time tomographic studies using data from the International Seismological Centre (ISC) catalog determine a large-scale subhorizontal high velocity anomaly in the northwestern Pacific subduction zones and it has been interpreted as imaging stagnant slab in the upper mantle transition zone (~400 to 700 km). The limited resolution of the travel time tomographic studies in this depth range, however, makes it difficult to evaluate accurately the vertical and lateral extent of a stagnant slab. A broadband waveform modeling of triplicated regional seismic waves which are very sensitive to the transition zone structure is useful to evaluate the velocity structure along the propagation paths and therefore to constrain the spatial distribution of anomalies. This study thus compares tomographic images from the model of Obayashi t et al. (1997) with results of the regional waveform modeling by Tajima and Grand (1998). The ISC tomographic model shows the largest lateral extent of high velocity anomaly in the layer of 478 to 551 km depths although part of this spread is likely due to the deteriorated resolution in that depth range. The waveform modeling suggests that the strong high velocity anomaly associated with a stagnant slab exists below 525 km with its maximum intensity in the top 50 km and decreases with increasing depth to vanish at 660 km. These results along with a recent global SH velocity model SAW12D of Li and Romanowicz (1996) which has the strongest high velocity anomaly in a depth range 500-550 km may be integrated into an image of a stagnant slab. The anomalous velocity structure associated with a stagnant slab has its maximum intensity not immediately above the 660 km discontinuity but in a depth range ~100 km above it. This feature appears to be consistent with a thermo-chemical model of down-going slab in which a larger velocity contrast with the surrounding mantle is expected at a shallower depth of the transition zone. The ISC tomographic model and waveform modeling consistently show that the deflected slabs are not laterally continuous but are separated into a few subregions. Beneath the northeastern China where the resolution is good, the slab related anomaly above the 660 km discontinuity is accompanied by its downward extension into the lower mantle.

Tajima, F.; Fukao, Y.; Obayashi, M.; Sakurai, T.

1998-11-01

217

Molecular identification of Theileria parasites of northwestern Chinese Cervidae  

PubMed Central

Background Theileria and Babesia protozoan parasites are transmitted mainly by tick vectors. These parasites cause heavy economic losses to the live-stock industry, as well as affecting the health of wild animals in parasite-endemic areas. Identification of infectious agents in wild animals is not only crucial for species preservation, but also provides valuable information on parasite epidemiology. Here, we conducted a molecular surveillance study in Northwestern China to assess the prevalence of blood pathogens in cervids. Methods PCR analysis and microscopic evaluation of blood smears to detect Theileria- and Babesia-related diseases in Cervidae were conducted, in which 22 blood samples from red deer (n?=?22) in Qilian Mountain and 20 from sika deer (n?=?20) in Long Mountain were collected and tested for the presence of Theileria and Babesia. The 18S rRNA gene was amplified, and selected polymerase chain reaction (PCR)-positive samples were sequenced for species identification. Results PCR revealed that 9.1% of the Qilian Mountain samples and 20% of the Long Mountain samples were positive for Theileria uilenbergi; 90.09% of the Qilian Mountain samples (n?=?22) were positive for T. capreoli, but all of the Long Mountain samples (n?=?20) were negative for T. capreoli; no other Theileria or Babesia species were found. PCR showed that T. uilenbergi and T. capreoli were present in red deer in Qilian Mountain, while only T. uilenbergi was found in sika Deer in Long Mountain. The 18S rRNA gene sequences were aligned against the corresponding GenBank sequences of known isolates of Theileria and Babesia and subjected to phylogenetic analysis. The phylogenetic tree showed that the newly isolated Theileria spp. could be classified as belonging to two clades: one group belonged to the same clade as T. uilenbergi, the other to a clade containing T. capreoli. Conclusions Our results provide important data to increase understanding of the epidemiology of Cervidae theileriosis, and will assist with the implementation of measures to control theileriosis transmission to Cervidae and small ruminants in central China.

2014-01-01

218

Fossil eggshells from the Upper Cretaceous (Campanian) Fruitland Formation, New Mexico  

Microsoft Academic Search

Approximately 1500 eggshell fragments were recovered from a vertebrate bonebed (NMMNH L-4010) in the late Campanian Fruitland Formation in northwestern New Mexico, a locality that represents one of the few southern occurrences of fossil eggshells in North America. Here, we present the first description of Campanian eggshells from New Mexico and identify six different eggshell types (Continuoolithus sp., Porituberoolithus sp.,

Kohei Tanaka; Darla K. Zelenitsky; Thomas Williamson; Anne Weil; François Therrien

2011-01-01

219

Evidence for a Younger Dryas glacial advance in the Andes of northwestern Venezuela  

Microsoft Academic Search

Deposits of push moraine, outwash and glaciolacustrine sediments, recovered from two areas in the northwestern Venezuelan Andes document the latest Pleistocene advance of Mérida ice. Underlying peats provide maximum ages on till and outwash evidently emplaced during the Younger Dryas (YD) climatic event. One example recovered from the Humboldt Massif, where the farthest extent of YD ice buried peat in

William C. Mahaney; M. W. Milner; Volli Kalm; Randy W. Dirszowsky; R. G. V. Hancock; Roelf P. Beukens

2008-01-01

220

Decline in the Primary Productivity of Northwestern European Forests as a Consequence of Climate Aridization  

Microsoft Academic Search

Average annual age-dependent changes of carbon accumulation in the stemwood of major forest species (pine, spruce, and birch) of the taiga zone of the northwestern European Russia (Karelia) were analyzed. The changes in carbon accumulation were assessed by comparing carbon reserves in tree stands of various ages. Net primary productivity of photosynthesis (NPP) and the proportionality coefficient between respiratory decarboxylation

P. Yu. Voronin; P. V. Konovalov; V. K. Bolondinskii; L. K. Kaipiainen; Z.-J. Mao

2005-01-01

221

Integrated Passive and Active Source Seismic Investigation of the Northwestern Basin and Range Province  

Microsoft Academic Search

We utilized teleseismic receiver function techniques and active-source refraction seismology to study the crustal structure and continental rift processes responsible for the development of the NW corner of the Basin and Range province (BRP). Despite relatively low extension measured at the surface, the crust in northwestern Nevada is thin, raising the possibility that the region underwent flow of a ductile

E. Gashawbeza; D. W. Lerch; C. K. Wilson; S. L. Klemperer; E. L. Miller

2005-01-01

222

THE SKULL OF THE PISTOSAURAUGUSTASAURUSFROM THE MIDDLE TRIASSIC OF NORTHWESTERN NEVADA  

Microsoft Academic Search

The skull of Augustasaurus hagdornifrom the Middle Triassic of northwestern Nevada is described in detail, and compared to those of Pistosaurus and Plesiosaurus. New information amends the earlier description of the postcranial skeleton of Augustasaurus. Phylogenetic analysis corroborates the sister-group relationship of Augustasaurus and Pistosaurus. These two taxa form a clade that is the sister-group of Plesiosaurus. The paleobiogeographical implication

OLIVIER RIEPPEL; P. MARTIN SANDER; GLENN W. STORRS

2002-01-01

223

Regional correlation of deposition sequences in the southern Mesozoic marine province, northwestern Nevada  

Microsoft Academic Search

Strata of the Mesozoic marine province of a northwestern Nevada, deposited in subaerial to deep marine environment in a backarc basin, underwent severe deformation during the late Mesozoic. Restoration of stratigraphic relations among constituent volcanic, volcanogenic, carbonate, and continentally-derived siliciclastic rocks has been hampered by sparse biostratigraphic age control. Regional correlation of coeval facies is made possible by coupling depositional

J. I. Satterfield; J. S. Oldow

1993-01-01

224

Diachroneity of Basin and Range extension and Yellowstone hotspot volcanism in northwestern Nevada  

Microsoft Academic Search

Some of the earliest volcanic rocks attributed to the Yellowstone hotspot erupted from the McDermitt caldera and related volcanic centers in northwestern Nevada at 17 15 Ma. At that time, extensional faulting was ongoing to the south in central Nevada, leading some to suggest that the nascent hotspot caused or facilitated middle Miocene Basin and Range extension. Regional geologic relationships

Joseph P. Colgan; Trevor A. Dumitru; Elizabeth L. Miller

2004-01-01

225

Subsurface structure of southeastern Oregon and northwestern Nevada from an analysis of complete Bouguer gravity  

Microsoft Academic Search

A new complete Bouguer gravity map has been constructed for southeastern Oregon and northwestern Nevada. The objectives have been to determine the subsurface structure of southeastern Oregon, to look for indications of isostatic compensation for these structures, and to evaluate the continuation of Basin and Range extensional structures from Nevada into Oregon. The gravity map shows several prominent anomalies, some

J. S. II Granata; R. E. Karlin; D. L. Sawatzky; A. Griscom

1993-01-01

226

The skull of the pistosaur Augustasaurus from the Middle Triassic of northwestern Nevada  

Microsoft Academic Search

The skull of Augustasaurus hagdorni from the Middle Triassic of northwestern Nevada is described in detail, and compared to those of Pistosaurus and Plesiosaurus. New information amends the earlier description of the postcranial skeleton of Augustasaurus. Phylogenetic analysis corroborates the sister-group relationship of Augustasaurus and Pistosaurus. These two taxa form a clade that is the sister-group of Plesiosaurus. The paleobiogeographical

Olivier Rieppel; P. Martin Sander; Glenn W. Storrs

2002-01-01

227

Soil organic carbon dynamics as related to land use history in the northwestern Great Plains  

Microsoft Academic Search

Strategies for mitigating the global greenhouse effect must account for soil organic carbon (SOC) dynamics at both spatial and temporal scales, which is usually challenging owing to limitations in data and approach. This study was conducted to characterize the SOC dynamics associated with land use change history in the northwestern Great Plains ecoregion. A sampling framework (40 sample blocks of

Zhengxi Tan; Shuguang Liu; Carol A. Johnston; Thomas R. Loveland; Larry L. Tieszen; Jinxun Liu; Rachel Kurtz

2005-01-01

228

The Areal Pattern of Burned Tree Vegetation in the Subarctic Region of Northwestern Canada  

Microsoft Academic Search

Vegetation and terrain analyses of 1312 air photos spanning the subarctic, low arctic, and portions of the adjacent high boreal region of northwestern Canada permitted geographic characterization of the areal pattern of burned forest and forest-tundra vegetation. In terms of its lower areal extent of burns, and lower frequency of air photos showing burns, the forest-tundra is distinct from both

K. P. TIMONEY; ROSS W. WEIN

1991-01-01

229

New stygobiont copepods (Calanoida; Misophrioida) from Bundera Sinkhole, an anchialine cenote in north-western Australia  

Microsoft Academic Search

Two new taxa in the copepod orders Calanoida and Misophrioida are described from the flooded coastal karst of north-western Australia. Stygocyclopia australis sp. nov. is the first pseudocyclopiid calanoid to be reported from the continent, with other congeners distributed in anchialine environments of the Philippine, Balearic, and Canary archipelagos. The presence of a supernumerary spine on the outer margin of

DAMIÀ JAUME; GEOFFREY A. BOXSHALL; WILLIAM F. HUMPHREYS

2001-01-01

230

Mortality in Northwestern Bohemia in Periods of High and Low Air Pollution  

Microsoft Academic Search

Air pollution was higher in the industrial area of Northwestern Bohemia during the years 1982 - 1990 than from 1991 to 2000. The aim of the study was to determine whether daily total, cardiovascular (CVD) or respiratory mortality in this area was significantly different during the years 1982 - 1990 compared to the period 1991 - 2000. Poisson regression analyses

Jiri Skorkovsky; Frantisek Kotesovec

231

A paleomagnetic study of Mesozoic sediments from the Junggar and Turfan basins, northwestern China  

Microsoft Academic Search

Mesozoic sedimentary rocks have been collected from the Karamay area (northwestern Junggar block) and in the Turfan basin (northeastern Tarim block) for a paleomagnetic study with the aim of testing the rigid nature of these blocks and to better constrain their paleogeographic relationships within central Asia prior to the collision with India. The results from the Karamay area are disappointing,

Jean-Pascal Cogné; Chen Yan; Vincent Courtillot; Frédéric Rocher; Wang Gongque; Meixiang Bai; Hongzi You

1995-01-01

232

Late Cenozoic tectonic activity and its significance in the Northern Junggar Basin, Northwestern China  

Microsoft Academic Search

The Dingshan area located in the northern part of the Junggar Basin of northwestern China is a significant prospect area for sandstone-type uranium deposits in China, where mainly Cenozoic rocks were deposited. The Cenozoic strata can be divided into four units according to the prior data and our own field observation. Sedimentary studies indicate that most Cenozoic strata were deposited

Zhengle Chen; Jian Liu; Hongliang Gong; Fengbin Han; Stephanie Marion Briggs; Enjiu Zheng; Guo Wang

2011-01-01

233

Lake Evolution in the Tengger Desert, Northwestern China, during the Last 40,000 Years  

Microsoft Academic Search

Climatic changes inferred from lacustrine deposits and lake-level fluctuations in northwestern and central China are mainly based on paleoclimatic records from the Tibetan Plateau, while there is still a lack of data relating to the semiarid\\/arid desert regions of Inner Mongolia. In the Tengger Desert, different paleolake levels at Baijian Hu are documented by six paleoshorelines and stratified lake carbonates.

Hans-Joachim Pachur; Bernd Wünnemann; Hucai Zhang

1995-01-01

234

Extensive diversification of pebblesnails (Lithoglyphidae: Fluminicola) in the upper Sacramento River basin, northwestern USA  

Microsoft Academic Search

Mitochondrial DNA sequences from the cytochrome c oxidase subunit I (COI) and cytochrome b (cytb) genes were obtained from the nine extant, previously described species of the northwestern North American freshwater gas- tropod genus Fluminicola (commonly known as pebblesnails) and from a large number of taxonomically undescribed populations of these animals from the upper Sacramento River basin, California and Oregon,

ROBERT HERSHLERi; HSIU-PING LIU; TERRENCE J. FREST

2007-01-01

235

Shore platform abrasion in a para-periglacial environment, Galicia, northwestern Spain  

Microsoft Academic Search

The Schmidt Rock Test Hammer was used to study the effect of abrasion on shore platforms in Galicia, northwestern Spain. On platforms where tidally-induced weathering (salt, wetting and drying, etc.) is dominant, rock strength is significantly lower than in areas where abrasion is, or has been active in the recent past. This suggests that abrasion removes weathered surface material, exposing

R. Blanco-Chao; A. Pérez-Alberti; A. S. Trenhaile; M. Costa-Casais; M. Valcárcel-Díaz

2007-01-01

236

"A Child has Many Mothers": Views of Child Fostering in Northwestern Cameroon  

ERIC Educational Resources Information Center

This article examines 20 fostering arrangements in a growing urban community in northwestern Cameroon from the perspectives of those involved. Analysis of interviews with caregivers and birth mothers suggests that the nature of adult relationships is central to children's living arrangements. Three caregiver-mother relationship profiles are…

Verhoef, Heidi

2005-01-01

237

A STUDY OF THE GOALS AND CHARACTERISTICS OF EXTENSION CREDIT STUDENTS IN NORTHWESTERN MICHIGAN.  

ERIC Educational Resources Information Center

AN ANALYSIS WAS MADE OF THE GOALS AND CHARACTERISTICS OF STUDENTS ENROLLED IN EXTENSION CREDIT COURSES OFFERED BY MICHIGAN STATE UNIVERSITY IN NORTHWESTERN MICHIGAN DURING THE FALL OF 1959. ALSO CONSIDERED WERE DATA ON STUDENT PROBLEMS AND ON CONTACTS AND RELATIONSHIPS WITH THE UNIVERSITY. GROUP ADMINISTERED QUESTIONNAIRES WERE USED TO COLLECT…

HAGELBERG, MILTON JOHN

238

Deep-water sedimentary environments of the northwestern Weddell Sea and South Sandwich Islands, Antarctica  

Microsoft Academic Search

Two transects have been sampled using short cores (multi and box), seabed photography, video sequences, and sediment profile images across the northwestern Weddell Sea and South Sandwich Forearc, Antarctica. A total of 12 core stations were examined for sediment structure, texture and composition to determine their depositional history. Four of the core stations from the Weddell Continental Slope, Abyssal Plain

John A. Howe; Tracy M. Shimmield; Robert Diaz

2004-01-01

239

Evaluation of Rectangular and Circular Escape Vents in the Northwestern Hawaiian Islands Lobster Fishery  

Microsoft Academic Search

Research was conducted in Hawaii during 1984-1 987 to investigate the possibility that escape vents fitted in traps used by the commercial lobster fishery in the northwestern Hawaiian Islands would reduce the catch and mortality of sublegal spiny lobsters Panulim margrnatus (<50 mm tail width) and slipper lobsters Scyllurides spp. (< 56 mm tail width) without significantly reducing legal catch.

ALAN R. EVERSON; ROBERT A. SKILLMAN; JEFFREY J. POLOVINA

1992-01-01

240

Determination of flow characteristics in the aquifer of the Northwestern Peninsula of Yucatan, Mexico  

Microsoft Academic Search

Flow characteristics were studied in the Northwestern Peninsula of Yucatan, Mexico. The Yucatan aquifer is a mature karst system, influenced by the Ring of Cenotes (sinkholes). This zone of aligned sinkholes is a high-permeability zone with respect to its surroundings. The aquifer is unconfined within the study area. Water-level measurements at 48 locations were made in June and October 1994;

Birgit Steinich; Luis E. Marín

1997-01-01

241

Summer Cattle Transhumance and Wild Edible Plant Gathering in a Mapuche Community of Northwestern Patagonia  

Microsoft Academic Search

Cattle transhumance has been practiced since colonial times in Mapuche communities of northwestern Patagonia, which travelled seasonally along the Andean valleys from arid lands towards temperate forests. In this study, we analyzed how this migratory practice affects the abundance and variety of wild edible plants utilized by the Mapuche community of Paineo. Patterns of use for those who practice transhumance

Ana H. Ladio; Mariana Lozada

2004-01-01

242

Holocene lahar deposits in the Whakapapa catchment, northwestern ring plain, Ruapehu volcano (North Island, New Zealand)  

Microsoft Academic Search

The Holocene sedimentary record on the northwestern ring plain of Mount Ruapehu records intermittent volcanic activity over the past 9500 years that is not preserved by primary pyroclastic deposits. The sedimentary record of eruptive activity comprises packages of lahar deposits, representing rapid aggradation of the ring plain in response to increased sediment influx. During these times, large debris flows (calculated

Beth A. Palmer

1991-01-01

243

Evidence for bimodal hybrid zones between two species of char (Pisces: Salvelinus) in northwestern North America  

Microsoft Academic Search

Dolly Varden (Salvelinus malma, Pisces: Salmonidae) and bull trout (Salvelinus confluentus) have widely overlapping, but largely parapatric ranges in water- sheds in northwestern North America from Washington State to northern British Columbia. Genetic analysis of natural populations using diagnostic molecular markers revealed widespread local sympatry and hybridization with hybrids comprising 0-25% of the local samples. In a detailed analysis of

Z. Redenbach; E. B. Taylor

2003-01-01

244

Petroleum production platforms as sites for the expansion of ciguatera in the northwestern Gulf of Mexico  

Microsoft Academic Search

Ciguatera is a common human disease of tropical, coral reef ecosystems acquired by consuming finfish-containing ciguatoxins (CTX). There are few records of this disease in the northwestern Gulf of Mexico, a region characterized by soft muddy bottoms that are considered poor habitat for the CTX source dinoflagellate Gambierdiscus toxicus. However, the approximately 4000 petroleum production platforms and hundreds of state-sponsored

T. A. Villareal; S. Hanson; Steve Qualia; E. L. E. Jester; H. R. Granade; R. W. Dickey

2007-01-01

245

Review of hydrographic environmental factors that may influence anchovy habitats in northwestern Mediterranean  

Microsoft Academic Search

SUMMARY: This paper is a review of the hydrography of the northwestern Mediterranean. It examines, at several scales from basin-scale to local processes, water mass distribution, circulation and driving mechanisms and their variability. It is focused on those aspects that may influence the success of spawning and recruitment of anchovy: stratification processes, continental influence, frontal instabilities, mesoscale events and shelf-slope

JORDI SALAT

246

Crossing the Invisible Line: Establishing Co-Education at the University of Manchester and Northwestern University.  

ERIC Educational Resources Information Center

Asserts that, during the second half of the 19th Century, women in England and the United States increasingly sought and gained admission to higher education institutions. Describes the establishment of coeducation at the University of Manchester (England) and Northwestern University (Illinois) in terms of these cultural differences. (CFR)

Barnes, Sarah V.

1994-01-01

247

Crop losses caused by rice brown spot disease in mangrove swamps of northwestern Sierra Leone  

Microsoft Academic Search

The rice brown spot disease caused by Cochliobolus miyabeanus (Ito et Kurib.) Drechsl. ex Dast. = (Helminthosporium oryzae Breda da Haan) is a key disease in mangrove swamp rice ecosystem in Sierra Leone. On average, grain yield losses of 8.2–23.0% were caused by the pathogen in mangrove swamps of northwestern Sierra Leone in the 1983, 1984 and 1985 cropping seasons.

S. N. Fomba; N. Singh

1990-01-01

248

Analysis and tracking of convective cells over north-western Italy  

Microsoft Academic Search

The identification and storm-tracking of convective cells is one of the most interesting sectors of that field of meteorology known as nowcasting. In the present work the main behaviour of the convective cells above North-Western Italy was studied, , using the ARPA Piemonte weather radar. The analysis carried out evaluates the spatial and temporal distribution of many parameters that characterize

P. Davini; R. Cremonini; R. Bechini; C. Cassardo

2009-01-01

249

Comparison of wild edible plant diversity and foraging strategies in two aboriginal communities of northwestern Patagonia  

Microsoft Academic Search

We have compared edible plant richness, diversity and differential patterns of use in two Mapuche communities of Argentina. The populations of Rams and Cayulef are located in a herbaceous steppe, far from the temperate forests of northwestern Patagonia where their ancestors lived in the past. Ecological concepts and methods, such as diversity indices, niche breadth and optimal foraging theory have

Ana H. Ladio; Mariana Lozada

2003-01-01

250

Semi-Detailed Uranium Geochemical Survey in Northwestern Samar (27 March 1979-4 July 1979).  

National Technical Information Service (NTIS)

A uranium geochemical survey was conducted to delineate in detail the uranium prospective area(s) in northwestern Samar. A total of 805 stream sediments and 1.115 water samples were obtained from the target areas from uranium analysis. Geochemical anomali...

G. Santos M. Ogena G. Tauli

1980-01-01

251

A possible bedrock source for obsidian found in archeological sites in northwestern Alaska  

USGS Publications Warehouse

Recently discovered deposits of obsidian in the Koyukuk valley may be the long-sought-for source of obsidian found in archeological sites in northwestern Alaska. Obsidian from these deposits compares favorably in physical characteristics and sodium-manganese ratio with the archeological obsidian, and there is evidence that the deposits have been "mined" in the past.

Patton, Jr. , W. W.; Miller, T. P.

1970-01-01

252

Change in spatial characteristics of forest openings in the Klamath Mountains of northwestern California, USA  

Microsoft Academic Search

Change in the spatial characteristics of forest openings was investigated in three forested watersheds in north-western Siskiyou County, California totalling approximately 24,600 hectares. Watersheds with minimal human disturbance were chosen for study. However, fire suppression has been pervasive throughout. Characteristics of forest openings (area, perimeter, distance between neighboring openings) were measured on aerial photographs taken 41 years apart. An index

Carl N. Skinner

1995-01-01

253

The simplification of traditional vineyard based agroforests in northwestern Portugal: some ecological implications  

Microsoft Academic Search

In northwestern Portugal, peasants have developed complex vineyard (Vitis vinifera) systems comprising agroforests composed of host trees, vines, annual crops and in some cases animals. Until recently these vineyards suffered very few pest problems and received relatively low pesticide loads. In the last few years, new policy and market forces have prompted the conversion of many of these systems to

M. A. Altieri; C. I. Nicholls

2002-01-01

254

Transition in the cause of fever from malaria to dengue, Northwestern Ecuador, 1990-2011.  

PubMed

In tropical areas, the predominant cause of fever has historically been malaria. However by 2011, among febrile patients in northwestern Ecuador, dengue was identified in 42% and malaria in none. This finding suggests a transition in the cause of fever from malaria to other illnesses, such as dengue. PMID:24047566

Cifuentes, Sara G; Trostle, James; Trueba, Gabriel; Milbrath, Meghan; Baldeón, Manuel E; Coloma, Josefina; Eisenberg, Joseph N S

2013-10-01

255

Global Positioning System (GPS) estimates of crustal deformation in the Marmara Sea region, Northwestern Anatolia  

Microsoft Academic Search

In the Marmara Sea region the relative motion between the Anatolian and Eurasian lithosphere has been measured by means of the modern techniques of space geodesy using the Global Positioning System (GPS). In order to resolve in detail the kinematic field within the active earthquake belts of Northwestern Anatolia, two GPS campaigns were carried out across a dense network consisting

Christian Straub; Hans-Gert Kahle

1994-01-01

256

Conodont geothermometry of the lower Paleozoic from the Precordillera (Cuyania terrane), northwestern Argentina  

Microsoft Academic Search

The thermal history of the Precordillera terrane of northwestern Argentina has been constrained by the conodont colour alteration index (CAI) in combination with previously published paleothermal data (e.g., illite crystallinity and clay mineral assemblages). The pattern of paleotemperatures displays an increase in paleotemperatures to the west and south of the basin. This configuration shows a gradual and continuous transition from

Gustavo G. Voldman; Guillermo L. Albanesi; Víctor A. Ramos

2010-01-01

257

Epizootiology of sarcoptic mange in a population of cantabrian chamois ( Rupicapra pyrenaica parava) in Northwestern Spain  

Microsoft Academic Search

In May of 1993, an epizootic of sarcoptic mange (Sarcoptes scabiei) was detected in the chamois (Rupicapra pyrenaica parva) population of the Cantabrian Mountains in northwestern Spain. The epizootic initially spread across an area inhabited by some 1600 chamois. Mortality was lower than reported for other populations of ungulates. The maximum number of animals were affected from February to May.

Jesús Fernández-Morán; Soledad Gómez; Fernando Ballesteros; Pablo Quirós; José L. Benito; Carlos Feliu; José M. Nieto

1997-01-01

258

Estimate of gas hydrate resource, northwestern Gulf of Mexico continental slope  

Microsoft Academic Search

Estimates of gas hydrate sequestered on the northwestern Gulf of Mexico (NWGOM) continental slope are presented. The volume of gas hydrate reservoir is estimated based on the relationship between geologic setting, water depth and the gas hydrate stability zone. A conceptual model of gas hydrate occurrence defines two types of gas hydrate accumulations in the NW GOM: (1) structurally focused

Alexei V Milkov; Roger Sassen

2001-01-01

259

Prevalence of Tritrichomonas foetus infection in beef bulls in northwestern Spain  

Microsoft Academic Search

The purpose of this study was to investigate the prevalence of Tritrichomonas foetus infection in beef bulls in north-western Spain. The study area comprised of 350 herds (5909 cows and 102 bulls) managed under extensive or semi-extensive systems where natural mating alone or alternated with artificial insemination are used. The targets of this survey were bulls of 1 year of

S Mart??n-Gómez; R González-Paniello; J Pereira-Bueno; L. M Ortega-Mora

1998-01-01

260

Ecological Condition of Coastal Ocean Waters of the Northwestern Gulf of Mexico: 2011.  

National Technical Information Service (NTIS)

In August 2011, the NOAA National Ocean Service (NOS) conducted an assessment of the status of ecological condition of soft-bottom habitat and overlying waters of the continental shelf in the northwestern Gulf of Mexico (GOM). The original sampling design...

C. Cooksey E. F. Wirth J. L. Hyland M. H. Fulton W. L. Balthis

2013-01-01

261

THE EFFECTS OF MUNICIPAL PUMPING FROM A SHALLOW GLACIAL AQUIFER AT BRYAN, NORTHWESTERN OHIO1  

Microsoft Academic Search

The city of Bryan in northwestern Ohio has been recognized as the Fountain City because of its location within a well-known belt of flowing wells. Municipal pumping, however, has lowered the water table so that few wells in the vicinity of the city now flow naturally. The city plans to locate a new well field in its vicinity as the

JAMES M. KING; LON C. RUEDISILI

262

Epiphytic dinoflagellates associated with ciguatera in the northwestern coast of Cuba  

Microsoft Academic Search

The spatial and temporal abundance of epiphytic dinoflagellates associated with ciguatera was stud- ied over two annual cycles (March 1999 to March 2000 and March 2001 to March 2002) in the northwestern coast of Cuba. From 14 species of macroalgae (Phaeophyta, Chlorophyta, and Rhodophyta), 1340 samples were obtained identifying seven species as potentially noxious; five of them are new reports

Gilma Delgado; Carlos H. Lechuga-Devéze; Genoveva Popowski; Luis Troccoli; Cesar A. Salinas

2006-01-01

263

A predictive model of archaeological potential: An example from northwestern Belize  

Microsoft Academic Search

Binary Logistic Regression is used to identify areas of high archaeological potential in a portion of northwestern Belize. The predictive modeling process involves remotely sensed imagery, Geographic Information System (GIS) data and techniques, and multivariate statistical approaches. Predictive variables represent both the pre-historic current landscape of the ancient Maya and the present day physical landscape. An optimal predictive model obtained

Sallie Vaughn; Tom Crawford

2009-01-01

264

Uppermost Mantle and Crustal Structure Beneath the WP2 Borehole Seismic Observatory, the Northwestern Pacific Basin  

Microsoft Academic Search

In August 2000, the seafloor borehole seismological observatory WP-2 in the northwestern Pacific Basin was installed successfully during the ODP leg191. The magnetic lineations in this area show the lithosphere was formed in Late Jurassic to Early Cretaceous. In July 2002, we visited the WP-2 site to recover the data from the borehole seismometer. During this visit, we conducted a

K. Nakahigashi; M. Shinohara; T. Yamada; M. Arisaka; T. Kanazawa; K. Suyehiro; T. Sato

2002-01-01

265

Carbon isotopic composition of deep carbon gases in an ombrogenous peatland, northwestern Ontario, Canada  

Microsoft Academic Search

Radiocarbon dating and carbon isotope analyses of deep peat and gases in a small ombrogenous peatland in northwestern Ontario reveals the presence of old gases at depth that are 1000-2000 yr younger than the enclosing peat. The authors suggest that the most likely explanation to account for this age discrepancy is the downward movement by advection of younger dissolved organic

R. Aravena; B. G. Warner; D. J. Charman; L. R. Belyea; S. P. Mathur; H. Dinel

1993-01-01

266

Attracting a New Market to Northwestern's Undergraduate Programs: Older Women Living on the North Shore.  

ERIC Educational Resources Information Center

Women over age 25 represent a substantial age group that may be recruited to bolster undergraduate student recruitment efforts at Northwestern University and similar institutions of higher education. By 1990, the number of recruitable 18-year-olds will fall by 20 percent nationwide, causing financial hardship for many private colleges and…

Fox, Karen F. A.

267

Verb and sentence production and comprehension in aphasia: Northwestern Assessment of Verbs and Sentences (NAVS)  

Microsoft Academic Search

Background: Verbs and sentences are often impaired in individuals with aphasia, and differential impairment patterns are associated with different types of aphasia. With currently available test batteries, however, it is challenging to provide a comprehensive profile of aphasic language impairments because they do not examine syntactically important properties of verbs and sentences.Aims: This study presents data derived from the Northwestern

Soojin Cho-Reyes; Cynthia K. Thompson

2012-01-01

268

Simple models of solar radiation data for northwestern part of Turkey  

Microsoft Academic Search

An extensive statistical analysis of hourly, daily and monthly measured solar radiation has been performed for a site in the northwestern part of Turkey, leading to statistical models. These models are equally applicable in any part of the world with reassessment of the model parameters. The necessary physical interpretations of the model parameters and their temporal variations are also presented.

Zekai ?en; Elçin Tan

2001-01-01

269

Geologic evolution of Uinta-Piceance basin province, northwestern Colorado and northeastern Utah  

Microsoft Academic Search

The Uinta-Piceance basin province (UPBP) has a complex Phanerozoic history characterized by five distinct phases of basin development (1) The UPBP formed part of a continental platform shelf on the northwestern flank of North America during the early and middle Paleozoic. Cambrian through Mississippian strata consist mainly of carbonate rocks, shale, and quartzite; contain major unconformities; and thicken westward. (2)

S. Y. Johnson; M. L. Tuttle; B. H. Bryant; R. F. Dubiel; T. D. Fouch; K. J. Franczyk; V. J. S. Grauch; M. A. Grout; R. C. Johnson; C. M. Molenaar; D. J. Nichols; K. M. Nichols; V. F. Nuccio; F. Peterson; J. K. Pitman; W. J. Jr. Perry; C. J. Potter; D. L. Sawatzky; R. W. Jr. Scott; E. R. Verbeek; R. B. Wanty

1990-01-01

270

Northwestern scientists develop new drug that prevents spread of human prostate cancer cells in mice  

Cancer.gov

A new drug developed by Northwestern Medicine scientists prevented human prostate cancer cells transplanted into mice from spreading to other tissues without any toxic effects to normal cells or tissues. The drug turns off the "go" switch in the cancer cells and immobilizes them.

271

Hydrology and water-quality monitoring considerations, Jackpile uranium mine, northwestern New Mexico  

Microsoft Academic Search

The Jackpile Uranium Mine, which is on the Pueblo of Laguna in northwestern New Mexico was operated from 1953 to 1980. The small storage coefficients determined from three aquifer tests indicate that the Jackpile sandstone is a confined hydrologic system throughout much of the mine area. Sediment from the Rio Paguate has nearly filled the Paguate Reservoir near Laguna since

Zehner

1985-01-01

272

Education, Employment and Empowerment: The Case of a Young Woman in Northwestern China  

ERIC Educational Resources Information Center

As a marginalized region of the world, the rural Gansu Province of northwestern China provides an informative canvas on which to examine and understand the ways in which education contributes to the lives of local Muslim women and supports their goals for work. Specifically, this article highlights the role education plays in the life of one young…

Maslak, Mary Ann

2011-01-01

273

Thermal supplementing soil nutrients through biocomposting of night-soil in the northwestern Indian Himalaya  

Microsoft Academic Search

Agriculture is one of the prime activities of the hill people residing in the northwestern Indian Himalaya. However, poor soil fertility in these areas is a big hurdle to sustainable farming. The effects of washout of topsoil and its nutrients, year after year, due to the abundance of snowfall, avalanches, landslides and erosion further add to the woes of the

Santaram S. Oinam; Yashwant S. Rawat; Jagdish C. Kuniyal; S. C. R. Vishvakarma; Dinesh C. Pandey

2008-01-01

274

Spatial clustering of rangeland grasshoppers (Orthoptera: Acrididae) in the Qinghai Lake region of northwestern China  

Microsoft Academic Search

Geostatistical analyses were used to examine the pattern of spatial distribution of rangeland grasshoppers in the basin of Qinghai Lake in northwestern China. Two sampling expeditions were undertaken to collect relevant data. In the first case, data were collected across an area of 1295km2 to the west of the lake in August 1999. Moran’s I was used to analyze spatial

Shaoxiang Ni; Jeffrey A Lockwood; Yuchun Wei; Jiangjun Jiang; Yong Zha; Hongliang Zhang

2003-01-01

275

The relationship between Pacific Decadal and Southern Oscillations: Implications for the climate of northwestern Baja California  

Microsoft Academic Search

The relationship between the Southern Oscillation (SO) and the Pacific Decadal Oscillation (PDO) is stud - ied by means of forced and secondary forecast models of the PDO. These models are constructed with the same indices frequently associated to different aspects of the climate of northwestern Baja California, namely the Southern Oscillation Index and the Pacific Decadal Oscillation Index (SOI

E. G. Pavia

2009-01-01

276

A Differentially-Irrigated, Xeric Plant Demonstration Garden in Northwestern New Mexico  

Microsoft Academic Search

Outdoor watering restrictions, which are increasingly being imposed by municipalities to conserve finite water resources, may limit the selection of species that can be practically maintained in semi-arid urban landscapes. To assist in the process of selecting suitable species, a xeric plant demonstration garden was established in northwestern New Mexico to serve as an exhibit of more than 90 drought

Daniel Smeal; M. M. West; M. K. O'Neill; R. N. Arnold

277

Spawning migration and intraspecies differentiation of pink salmon from northwestern Sakhalin waters  

NASA Astrophysics Data System (ADS)

Pacific salmon fishery near the northwestern Sakhalin coast is based on fish spawning both in the island and continental rivers. Salmon fishery near the Sakhalin coast of Amur Estuary has significantly lost contact with the main salmon rivers of the region. Pink salmon is the most abundant salmon species of the region rivers. Biology of the northwestern Sakhalin pink salmon is less studied of all the fishery regions on the island. So far, their migratory ways from feeding and wintering areas to the spawning rivers have not been ascertained. The results of monitoring for pink salmon have shown that by some biological indices, commercial-statistic data, and also by the data of satellites NOAA-10, NOAA-12, NOAA-14, their commercial catches near the northwestern Sakhalin are formed by fish groups migrating both through the Amur Estuary from the south, and through the Sakhalin Bay from the north. The base of spawning fish in rivers of northwestern Sakhalin is formed by the summer pink salmon migrating from the north. A preliminary computation of distinguished pink salmon groups (summer southern and northern autumn) shows a ratio 0.1:5.7:1 in odd years and 1:2:1 in even years.

Ivanov, Alexander N.; Shershnev, Alexej; Kaplanova, Nina P.; Pusankov, Konstantin L.; Ivanova, Lubov V.; Pusankova, Ekaterina N.

2002-03-01

278

Late Neoproterozoic paleomagnetic results from the Sugetbrak Formation of the Aksu area, Tarim basin (NW China) and their implications to paleogeographic reconstructions and the snowball Earth hypothesis  

Microsoft Academic Search

In order to better constrain the Neoproterozoic paleogeographic reconstruction of continents and to improve the understanding of the snowball Earth hypothesis, paleomagnetic investigations were carried out in the Aksu area of the northwestern Tarim basin. Forty-eight sites of samples were collected from the Sugetbrak and Chigebrak Formations. Twenty-four sites of sandstone and volcanic rock from the Sugetbrak Formation revealed stable

Sheng Zhan; Yan Chen; Bei Xu; Bo Wang; Michel Faure

2007-01-01

279

Evolution of Middle to Late Pleistocene Sandy Calcareous Palaeosols Underlying the Northwestern Negev Desert Dunefield (Israel)  

NASA Astrophysics Data System (ADS)

Calcareous palaeosols in the northwestern (NW) Negev Desert dunefield, Israel, at the eastern end of the Sinai-Negev erg were studied in relation to their overlying stabilized dunes and downwind loess deposits, using sedimentological analyses, spectroscopy, and optically stimulated luminescence (OSL) dating. During the Middle to Late Pleistocene, between around MIS 7 and through MIS 3, several cycles of sand veneer (sheet) deposition, stabilization, pedogenesis, and erosion formed a spatially variable sequence of sandy calcareous palaeosols in the NW Negev. Periods of stability on the order of several thousand years to over ten thousand years, characterized by post-depositional illuviation of aeolian silts, clays, and salts, enabled the formation of diagnostic, often-indurated, calcareous, Bk horizons (stages I-III), with orthic carbonate nodules. The primary particle-size mode of the palaeosol (127 µm) is intermediate between the modes of the overlying (MIS 2) dune sand and the mode of primary northern Negev (~MIS 6 through MIS 2) loess deposits in the dunefield periphery. The sand fraction of the palaeosols is slightly finer than the dune sand, and its spatial sedimentation pattern correlates with the pattern of the subsequent dune incursions. These observations suggest that (1) Bk palaeosol horizons were resistant to (MIS 6 - MIS 3) sand veneer aeolian erosion and formed chronologically differentiated and durable surfaces; (2) these surfaces remained in equilibrium for extensive periods, being intermittently covered and preserved by shifting sand veneers; (3) the MIS 2 dune incursion episodes followed the same transport routes of the underlying palaeosol sand substrate while producing a limited amount of aeolian erosion on the Bk horizons, and; (4) the similar sedimentological and chronological framework of the palaeosols and loess deposits suggests a partial genetic connection. As for the overlying dunes, aeolian sand supply to the parent material of the palaeosols was initially controlled by sediment availability originating in the Nile Delta and probably linked to glacial-interglacial eustatic cycles and glacial and cold-event windiness. The NW Negev sand deposition episodes that markedly differ from the ages of a nearby sandy palaeosol sequence of coastal origin exemplify the role of sand supply on the development of palaeosol sequences in a similar palaeoclimate.

Roskin, Joel; Katra, Itzhak; Porat, Naomi; Zilberman, Ezra

2014-05-01

280

Impact of improved technology on potential reserves of tight gas in East Texas and Northwestern Louisiana. Final topical report, October 1, 1989-September 30, 1990  

SciTech Connect

The East Texas/Northwestern Louisiana area has been one of the most active tight gas plays over the past decade. Advances in formation evaluation and stimulation technologies offer the prospect of increased reserves at reduced costs from remaining tight gas resource. The purpose of the study was to estimate the remaining potential production from the low permeability portions of the Cotton Valley and Travis Peak Formations, the largest tight gas formations in the area. For a 14,000 square mile study area that straddles the Texas/Louisiana border and the Sabine Uplift, a remaining estimated 2.8 Tcf is technically recoverable from the Cotton Valley Sand and 1.2 Tcf from the Upper Travis Peak. These estimates were based on a regional geologic appraisal of currently producing reservoirs. Typical wells were analyzed and used as the basis to extrapolate expected future production from the remaining undeveloped areas of these reservoirs. The analysis incorporated potential improvements in formation evaluation and stimulation technologies and current costing and industry financial parameters to estimate potential reserves at alternative wellhead prices. Reservoir data and analysis results can be used to identify which geological and technical parameters are most important to efficient recovery of East Texas tight sands. Three case studies are also presented of improved technologies in the study area over the past decade. The studies indicate that technology improvements have been made in the design and implementation of new stimulation technologies, as well as in formation evaluation and reservoir management.

Haas, M.R.

1990-12-01

281

Cenozoic orogenic phases in the northwestern framing of the Pacific  

NASA Astrophysics Data System (ADS)

Several Cenozoic orogenic phases marked by deformations and rearrangement of geological structures, by unconformities and hiatuses, and by the cyclicity of ancient sedimentary and volcanic formations are distinguished in the vast territory of a transitional zone between Northeast Asia and the Pacific, from Sakhalin in the south to Chukotka in the north.

Gladenkov, Yu. B.

2013-07-01

282

Observations of anticyclonic and cyclonic Subthermocline Submesoscale Coherent Vortices: a case study in the Northwestern Mediterranean Sea  

NASA Astrophysics Data System (ADS)

The surface geostrophic turbulence is mainly constituted by strong surface intensified eddies formed by boundary current instability, whereas within the interior of the ocean smaller vortical structures appear to be prominent. They are called Submesoscale Coherent Vortices (SCVs) and are known to be long-lived features. They are particularly efficient in transporting tracers (like temperature, salinity, dissolved oxygen for instance) over long distances. Anticylonic SCVs have been commonly observed in several oceans since the late 70s and the discovery of the Meddies, but less is known about cyclonic SCVs, which were hypothesized to be less stable and therefore harder to observe. Mooring data, cruises and in particular, regular deployments of gliders in the Northwestern Mediterranean Sea since 2007 revealed the presence of several anticyclonic and cyclonic SCVs. They are both characterized by small radius (~5-10km, about the internal radius of deformation of the area), velocity maxima at intermediate depth of ~5-15cm/s, high Rossby numbers of 0.1-0.5 and local Potential Vorticity anomalies. In this study, we present a census and a dynamical description of the encountered SCVs, as well as a discussion on their formation process and role in the ocean circulation.

Bosse, Anthony; Testor, Pierre; Mortier, Laurent; Houpert, Loïc

2014-05-01

283

Petrography of Neocomian sandstones in western Brooks Range, and Tunalik, Klondike and Burger Wells, northwestern Arctic Slope-Chukchi Sea  

SciTech Connect

Petrographic examinations were performed on Neocomian sandstones of the Ellesmerian sequence in outcrop in the western Brooks Range and from cuttings and cores from wells in the northwestern part of the National Petroleum Reserve in Alaska (NPRA) and adjacent Chukchi Sea that are probably coeval with the Kuparuk River Formation in the Prudhoe Bay area. Close similarities are recognized among samples from the 300 foot thick Tingmerkpuk Sandstone, which crops out in the western DeLong Mountains, and samples of apparently coeval intervals in the Tunalik, Burger, and Klondike wells. All are quartzose sublitharenities-quartzarenities that are dominantly fine to very-fine grained, with a few medium-to-coarse-grained sands. Grains are generally well-to very well-sorted, with minor detrital clays. Other framework grains include minor to trace amounts of cherts, argillaceous rocks, carbonate glauconite are commonly present, as rounded peloids, sometimes deformed between more rigid grains. Cements are principally quartz and/or carbonates, with diagenetic clays in a few samples. Notable porosity occurs in some core from the Tunalik well, but is not obvious in these cuttings or outcrop samples (other data indicate porosity in both other wells). Although petrographic characteristics alone do not establish a correlation among these widely spaced control points, the similarities support a common tectonic/stratigraphic framework for the Neocomian in all the areas. Regional stratigraphic studies of these sandstones suggest potential for significant reservoir quality associated with possible stratigraphic traps in the subsurface.

Mowatt, T.C.; Banet, A.C. [Bureau of Land Management, Anchorage, AK (United States); Mull, C.G. [Alaska Division of Geological and Geophysical Surveys, Fairbanks, AK (United States); Wilson, M.D. [Consultant, Golden, CO (United States); Reeder, J.W. [Alaska Division of Geological and Geophysical Surveys, Eagle River, AK (United States)

1995-04-01

284

Life in the sublittoral zone of long-lived Lake Pannon: paleontological analysis of the Upper Miocene Szák Formation, Hungary  

Microsoft Academic Search

Life and depositional environments in the sublittoral zone of Lake Pannon, a large, brackish Paratethyan lake from the Late\\u000a Miocene, were reconstructed from fossils and facies of the Szák Formation. This formation is exposed in several, roughly coeval\\u000a (9.4–8.9 Ma) outcrops, located along strike of the paleo-shelf-break in northwestern Hungary. The silty argillaceous marl\\u000a of the formation was deposited below storm

István Cziczer; Imre Magyar; Radovan Pipík; Madelaine Böhme; Stjepan ?ori?; Koraljka Bakrac; Mária Süto-Szentai; Miklós Lantos; Pál Müller

2009-01-01

285

Detailed three-dimensional shear wave velocity structure of the northwestern United States from Rayleigh wave tomography  

NASA Astrophysics Data System (ADS)

Since the mid-Miocene, the northwestern United States has experienced extensive flood basalt volcanism, followed by the formation of two time-progressive tracks of silicic volcanism: the Yellowstone/Snake River Plains (YSRP) and the High Lava Plains (HLP). The YSRP track progresses towards the northeast, parallel to North American plate motion, and has therefore often been attributed to a deep mantle plume source. However, the HLP track progresses to the northwest over the same time frame in a direction not consistent with any regional plate motion. The causes of the mid-Miocene flood basalts and the tracks of the YSRP and HLP are a matter of ongoing debate. We present results of Rayleigh wave phase velocity inversions and inversions for 3-D shear wave velocity structure of the northwestern United States using data collected from the High Lava Plains seismic experiment and the EarthScope USArray Transportable Array (TA). The large number of stations used in these inversions allows us to show an unprecedented level of detail in the seismic velocity structures of this tectonically complex area. Our velocity images indicate that low S-wave velocities in the uppermost mantle do not well match the track of HLP volcanism. While at the surface the Newberry caldera appears to anchor the NW end of the HLP hotspot track, the seismic results show that it lies in a separate, north-south trending low velocity band just east of the Cascades that is distinct from the main HLP trace. The ultra-low S-wave velocities beneath the YSRP track extend locally to at least 175 km depth and are by far the most prominent seismic anomalies in the region. Along axis, the YSRP hotspot track is characterized by a discrete low velocity channel in the upper mantle that shallows, narrows and intensifies to the northeast, but then deepens rapidly to the north beneath Yellowstone. The shallowing of the low velocity anomaly to the northeast is consistent with a stationary heat source beneath a moving plate, coupled with Basin and Range extension and heating.

Wagner, Lara; Forsyth, Donald W.; Fouch, Matthew J.; James, David E.

2010-11-01

286

Aeolian transport pathways along the transition from Tibetan highlands towards northwestern Chinese deserts  

NASA Astrophysics Data System (ADS)

The identification and semi-quantification of aeolian transport pathways enhances the understanding of aeolian sediment archive formation and thus supports reliability and explanatory power concerning palaeoenvironmental reconstructions. Grain size analysis of 279 surface sediment samples from the transition of Tibetan highlands (Qilian Shan) towards northwestern Chinese deserts allows the differentiation of contributing pathways among three types of aeolian sediments: silty loess, sandy loess, and aeolian sands. The study area exhibits a high diversity of geomorphological surfaces due to varieties in relief, elevation and climatic conditions. Therefore, it provides the opportunity to investigate the characteristics of sediments in different geomorphological settings. Using the peaks of grain size frequency's standard deviation of primary loess allows identification of the most sensitive fractions to varying accumulation conditions. mU/fS-ratio (7 - 13 ?m / 58 - 84 ?m) of primary silty loess relates the far-travelled dust proportion to the locally transported fine sand component. In vicinity to fluvial channels in the foreland mU/fS-values are significantly decreased, whereas mU/fS-values increase with altitude (r2 = 0.74). This indicates higher contribution of long distance transport compared to lower regions. A prominent increase of mU/fS-values above 3000 m asl likely indicates an increasing contribution of fine and medium silt particles transported by Westerlies in higher altitudes. In contrast, lower areas seem to be more strongly influenced by low altitude monsoon currents (NW-Winter- / SE-summer monsoon). The difference in grain size properties is additionally enhanced by the contrasting geomorphologic settings along the mountain declivity: Plain foreland alluvial fans support fine sand supply and availability whereas steep high mountain topography provides only limited potential for fine sand deflation. Similarly, the relatively low relief in intramontane basins leads to fluvial sediment aggradation and allows comparably high fine sand deflation. This supports the formation of sandy loess in these regions and on foreland alluvial fans, whereas in contrast, sandy loess is absent in the high mountain geomorphologic setting. Aeolian sand distribution in the study area indicates a high dependence on sand supply. In eastern forelands perennial Hei River and northerly bordering Badain Jaran desert are important sand sources and hence support dune field formation in the northern Qilian Shan foreland (Hexi Corridor). In contrast, western forelands, dominated by gravel gobi surfaces, exhibit very few aeolian sand accumulations on the surface. The latter area shows only ephemeral discharge and is lacking large sand source areas. Therefore, although sufficient wind speeds occur, aeolian sand transport is limited due to restricted sand supply. Concluding, the medium scale geomorphological setting (103 m) exerts a rather underestimated influence when reconstructing aeolian transport processes. However, considering the spatial distribution of aeolian sediments in combination with their grain size distribution allows the reconstruction of dominant transport pathways.

Nottebaum, Veit; Lehmkuhl, Frank; Stauch, Georg

2014-05-01

287

Digital data sets that describe aquifer characteristics of the alluvial and terrace deposits along the Cimarron River from Freedom to Guthrie in northwestern Oklahoma  

USGS Publications Warehouse

ARC/INFO export and nonproprietary format files This diskette contains digitized aquifer boundaries, maps of hydraulic conductivity, recharge, and ground-water level elevation contours for the alluvial and terrace deposits along the Cimarron River from Freedom to Guthrie in northwestern Oklahoma. Ground water in 1,305 square miles of Quaternary-age alluvial and terrace deposits along the the Cimarron River from Freedom to Guthrie is an important source of water for irrigation, industrial, municipal, stock, and domestic supplies. Alluvial and terrace deposits are composed of interfingering lenses of clay, sandy clay, and cross-bedded poorly sorted sand and gravel. The aquifer is composed of hydraulically connected alluvial and terrace deposits that unconformably overlie the Permian-age Formations. The aquifer boundaries are from a ground-water modeling report on the alluvial and terrace aquifer along the Cimarron River from Freedom to Guthrie in northwestern Oklahoma and published digital surficial geology data sets. The aquifer boundary data set was created from digital geologic data sets from maps published at a scale of 1:250,000. The hydraulic conductivity values, recharge rates, and ground-water level elevation contours are from the ground-water modeling report. Water-level elevation contours were digitized from a map at a scale of 1:250,000. The maps were published at a scale of 1:900,000. Ground-water flow models are numerical representations that simplify and aggregate natural systems. Models are not unique; different combinations of aquifer characteristics may produce similar results. Therefore, values of hydraulic conductivity and recharge used in the model and presented in this data set are not precise, but are within a reasonable range when compared to independently collected data.

Adams, G. P.; Runkle, Donna; Rea, Alan; Cederstrand, J. R.

1997-01-01

288

75 FR 3487 - Notice of Public Meeting: Recreation Subcommittee of the Sierra Front-Northwestern Great Basin...  

Federal Register 2010, 2011, 2012, 2013

...Subcommittee of the Sierra Front-Northwestern Great Basin, Northeastern...Resource Advisory Councils, Nevada AGENCY: Bureau of Land Management...Land Management's (BLM) Nevada Resource Advisory Committees...Highway 159, Las Vegas, Nevada. FOR FURTHER INFORMATION...

2010-01-21

289

Giardiasis as zoonosis: between proof of principle and paradigm in the Northwestern region of São Paulo State, Brazil  

Microsoft Academic Search

ObjectiveIn order to evaluate the potential zoonotic transmission of Giardia duodenalis, isolates from humans and dogs in the Northwestern region of the São Paulo State, Brazil were characterized based on the ?-giardin gene.

Aline Cardoso Caseca Volotão; Nathália Motta Delvaux Ramos; Maria Fantinatti; Marcus Vinícius Proença de Moraes; Halim Atique Netto; Luciane Moreno Storti-Melo; Elenir Alves Macedo de Godoy; Andréa Regina Baptista Rossit; Octávio Fernandes; Ricardo Luiz Dantas Machado

2011-01-01

290

33 CFR 165.1301 - Puget Sound and Adjacent Waters in Northwestern Washington-Regulated Navigation Area.  

Code of Federal Regulations, 2013 CFR

33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Puget Sound and Adjacent Waters in Northwestern Washington-Regulated...165.1301 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF...

2013-07-01

291

Population Size and Trends for Nesting Ospreys in Northwestern Mexico: Region-wide Surveys, 1977, 1992/1993 and 2006.  

National Technical Information Service (NTIS)

We used a double-sampling technique (air plus ground survey) in 2006, with partial double coverage, to estimate the present size of the osprey (Pandion haliaetus) nesting population in northwestern Mexico. With the exception of Natividad, Cedros, and San ...

A. C. Veraan C. J. Henny D. W. Anderson J. L. E. Cartron

2007-01-01

292

33 CFR 165.1301 - Puget Sound and Adjacent Waters in Northwestern Washington-Regulated Navigation Area.  

Code of Federal Regulations, 2012 CFR

33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Puget Sound and Adjacent Waters in Northwestern Washington-Regulated...165.1301 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF...

2012-07-01

293

33 CFR 165.1301 - Puget Sound and Adjacent Waters in Northwestern Washington-Regulated Navigation Area.  

Code of Federal Regulations, 2011 CFR

33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Puget Sound and Adjacent Waters in Northwestern Washington-Regulated...165.1301 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF...

2011-07-01

294

Genetic relationships of tui chub populations in the northwestern Great Basin and conservation implications for the Cow Head Tui Chub  

Microsoft Academic Search

The Cow Head Tui Chub, Siphateles thalassinus vaccaceps, is restricted to the small Cow Head basin in far northeastern California and northwestern Nevada. Using microsatellite DNA\\u000a loci, we found extensive genetic variation among tui chub populations in the Cow Head and surrounding basins of the northwestern\\u000a Great Basin. Our data support the systematic conclusions of earlier authors, while showing distinct

Yongjiu Chen; Stewart Reid; Bernie May

2009-01-01

295

Seismic refraction and potential field modeling of the northwestern Basin and Range transition zone, Nevada and California  

Microsoft Academic Search

Seismic-velocity and potential-field modeling along an E-W profile provides new constraints on the crustal structure of the northwestern Basin and Range transition zone. Our data span the change in tectonic setting from low-magnitude (<15%) Basin and Range extension in northwestern Nevada to relatively unextended volcanic plateaus in northeastern California, effectively filling the gap in geophysical data between the 1986 PASSCAL

J. M. Glen; D. D. Lerch; S. S. Klemperer; D. A. Ponce

2005-01-01

296

Tissue Distribution of Selenium and Effect of Season and Age on Selenium Content in Roe Deer from Northwestern Poland  

Microsoft Academic Search

The aim of the study was to compare selenium concentrations in different organs of roe deer from northwestern Poland. Samples\\u000a of liver, kidneys, heart and lungs, collected from 74 roe deer shot during the hunting seasons of 2008–2009 in northwestern\\u000a Poland, were studied. Selenium concentration in the organs was determined spectrofluorimetrically. Mean selenium concentration\\u000a was 0.06 µg\\/g w.w. in the liver,

Bogumi?a Pilarczyk; Agnieszka Tomza-Marciniak; Renata Pilarczyk; Diana Hendzel; Barbara B?aszczyk; Ma?gorzata B?kowska

2011-01-01

297

Preliminary estimation of the tsunami hazards associated with the Makran subduction zone at the northwestern Indian Ocean  

Microsoft Academic Search

We present a preliminary estimation of tsunami hazard associated with the Makran subduction zone (MSZ) at the northwestern\\u000a Indian Ocean. Makran is one of the two main tsunamigenic zones in the Indian Ocean, which has produced some tsunamis in the\\u000a past. Northwestern Indian Ocean remains one of the least studied regions in the world in terms of tsunami hazard assessment.

Mohammad Heidarzadeh; Moharram D. Pirooz; Nasser H. Zaker; Ahmet C. Yalciner

2009-01-01

298

Dinosaur Tracks from the Kilmaluag Formation (Bathonian, Middle Jurassic) of Score Bay, Isle of Skye, Scotland, UK  

Microsoft Academic Search

Tracks of a juvenile theropod dinosaur with footprint lengths of between 2 and 9 cm as well as adults of the same ichnospecies with footprints of about 15–25 cm in length were found in the Bathonian (Middle Jurassic) Kilmaluag Formation of Score Bay, northwestern Trotternish Peninsula, Isle of Skye, Scotland, UK. Two footprint sizes occur together on the same bedding

Neil D. L. Clark; Dugald A. Ross; Paul Booth

2005-01-01

299

Palaeomagnetic evidence for unification of the North and West Australian cratons by ca.1.7Ga: new results from the Kimberley Basin of northwestern Australia  

NASA Astrophysics Data System (ADS)

A palaeomagnetic study of the Elgee Formation red siltstones and shales in the Palaeoproterozoic Kimberley Basin of northwestern Australia has been carried out. All seven sampling sites revealed an extremely stable magnetic remanence carried by haematite. The age of the formation is confined by precise SHRIMP U-Pb ages of early diagenetic xenotime from rocks both above and below it to be 1704+7/-14Ma, but this may represent a minimum age. The youngest detrital zircon grains in the underlying formation provide a maximum age of 1786+/-14Ma for the formation. The extreme stability of the remanence, the dissimilarity of the remanent direction from expected younger palaeomagnetic directions, and the lack of regional overprint in the 1790+/-4Ma Hart Dolerite just north of the study region support a primary origin for the remanence. A marginally positive fold test also supports a primary origin. The mean direction of D=92.2°, I=14.9°, ?95=6.4° gives a palaeopole at 4.4°S, 210.0°E with dp=3.3°, dm=6.5°. This pole, a previously reported palaeopole from the Hart Dolerite and ca. 1700Ma overprint poles from the Pilbara Craton all agree with palaeopoles of similar ages from the McArthur Basin of northern Australia. Palaeomagnetic results thus suggest that the North and West Australian cratons were possibly joined together by approximately 1.7Ga.

Li, Z. X.

2000-07-01

300

Abundances of northwestern salamander larvae in montane lakes with and without fish, Mount Rainier National Park, Washington  

USGS Publications Warehouse

In Mount Rainier National Park, the northwestern salamander usually inhabits relatively large and deep lakes and ponds (average size = 0.3 ha; average depth > 2 m) that contain flocculent, organic bottom sediments and abundant coarse wood. Prior to 1970, salmonids were introduced into many of the park's lakes and ponds that were typical habitat of the northwestern salamander. The objective of this study was to compare, in lakes and ponds with suitable habitat characteristics for northwestern salamanders, the observed abundances of larvae in takes and ponds with and without these introduced salmonids. Day surveys of 61 lakes were conducted between 1993 and 1999. Fish were limited to takes and ponds deeper than 2 in. For the 48 lakes and ponds deeper than 2 in (i.e., 25 fishless lakes and 23 fish lakes), the mean and median observed abundances of northwestern salamander larvae in fishless lakes and ponds was significantly greater than the mean and median observed abundances of larvae in lakes and ponds with fish. Northwestern salamander larvae were not observed in 11 fish lakes. These lakes were similar in median elevation, surface area, and maximum depth to the fishless lakes. The 12 fish lakes with observed larvae were significantly lower in median elevation, larger in median surface area, and deeper in median maximum depth than the fishless lakes. Low to null observed abundances of northwestern salamander larvae in lakes and ponds with fish were attributed to a combination of fish predation of larvae and changes in larval behavior.

Larson, Gary L.; Hoffman, Robert L.

2002-01-01

301

Summary of reported agriculture and irrigation water use in northwestern Arkansas counties, 1991  

USGS Publications Warehouse

This report summarizes the 1991 water-use reporting through the Conservation District Offices in the following northwestern Arkansas counties: Baxter, Benton, Boone, Carroll, Cleburne, Fulton, Izard, Madison, Marion, Newton, Searcy, Sharp, Stone, Van Buren, and Washington. The number of withdrawal registrations for northwestern Arkansas counties was 106 (16 groundwater and 90 surface water). Water withdrawals reported during the registration process total 41.72 Mgal/d (0.74 Mgal/d groundwater and 40.98 Mgal/d surface water) for agriculture and 3.33 Mgal/d (0.27 Mgal/d groundwater and 3.06 Mgal/d surface water) for irrigation. The registration reports for 1991 indicate that this water was applied to 3,588 acres of land to irrigate rice, soybeans, cash grains, hay, oats, vegetables, sod, berries, fruit trees, and timber as well as for the agricultural use of animal aquaculture.

Holland, T. W.; Manning, C. A.; Stafford, K. L.

1993-01-01

302

Pre-, syn-, and postcollisional stratigraphic framework and provenance of upper triassic-upper cretaceous strata in the northwestern talkeetna mountains, alaska  

USGS Publications Warehouse

Mesozoic strata of the northwestern Talkeetna Mountains are located in a regional suture zone between the allochthonous Wrangellia composite terrane and the former Mesozoic continental margin of North America (i.e., the Yukon-Tanana terrane). New geologic mapping, measured stratigraphic sections, and provenance data define a distinct three-part stratigraphy for these strata. The lowermost unit is greater than 290 m thick and consists of Upper Triassic-Lower Jurassic mafic lavas, fossiliferous limestone, and a volcaniclastic unit that collectively we informally refer to as the Honolulu Pass formation. The uppermost 75 m of the Honolulu Pass formation represent a condensed stratigraphic interval that records limited sedimentation over a period of up to ca. 25 m.y. during Early Jurassic time. The contact between the Honolulu Pass formation and the overlying Upper Jurassic-Lower Cretaceous clastic marine strata of the Kahiltna assemblage represents a ca. 20 m.y. depositional hiatus that spans the Middle Jurassic and part of Late Jurassic time. The Kahiltna assemblage may to be up to 3000 m thick and contains detrital zircons that have a robust U-Pb peak probability age of 119.2 Ma (i.e., minimum crystallization age/maximum depositional age). These data suggest that the upper age of the Kahiltna assemblage may be a minimum of 10-15 m.y. younger than the previously reported upper age of Valanginian. Sandstone composition (Q-43% F-30% L-27%-Lv-71% Lm-18% Ls-11%) and U-Pb detrital zircon ages suggest that the Kahiltna assemblage received igneous detritus mainly from the active Chisana arc, remnant Chitina and Talkeetna arcs, and Permian-Triassic plutons (Alexander terrane) of the Wrangellia composite terrane. Other sources of detritus for the Kahiltna assemblage were Upper Triassic-Lower Jurassic plutons of the Taylor Mountains batholith and Devonian-Mississippian plutons; both of these source areas are part of the Yukon-Tanana terrane. The Kahiltna assemblage is overlain by previously unrecognized nonmarine strata informally referred to here as the Caribou Pass formation. This unit is at least 250 m thick and has been tentatively assigned an Albian-Cenomanian-to-younger age based on limited palynomorphs and fossil leaves. Sandstone composition (Q-65% F-9% L-26%-Lv-28% Lm-52% Ls-20%) from this unit suggests a quartz-rich metamorphic source terrane that we interpret as having been the Yukon-Tanana terrane. Collectively, provenance data indicate that there was a fundamental shift from mainly arc-related sediment derivation from sources located south of the study area during Jurassic-Early Cretaceous (Aptian) time (Kahiltna assemblage) to mainly continental margin-derived sediment from sources located north and east of the study area by Albian-Cenomanian time (Caribou Pass formation). We interpret the threepart stratigraphy defined for the northwestern Talkeetna Mountains to represent pre- (the Honolulu Pass formation), syn- (the Kahiltna assemblage), and post- (the Caribou Pass formation) collision of the Wrangellia composite terrane with the Mesozoic continental margin. A similar Mesozoic stratigraphy appears to exist in other parts of south-central and southwestern Alaska along the suture zone based on previous regional mapping studies. New geologic mapping utilizing the three-part stratigraphy interprets the northwestern Talkeetna Mountains as consisting of two northwest-verging thrust sheets. Our structural interpretation is that of more localized thrust-fault imbrication of the three-part stratigraphy in contrast to previous interpretations of nappe emplacement or terrane translation that require large-scale displacements. Copyright ?? 2007 The Geological Society of America.

Hampton, B. A.; Ridgway, K. D.; O'Neill, J. M.; Gehrels, G. E.; Schmidt, J.; Blodgett, R. B.

2007-01-01

303

The Hei River Basin in northwestern China - tectonics, sedimentary processes and pathways  

NASA Astrophysics Data System (ADS)

The Hei River Basin (catchment area of c. 130,000 km²) is situated at the transition between the northern margin of the Tibetan Plateau and the southern slopes of Gobi-Tien-Shan. As part of the northwestern Chinese deserts, the Ejina Basin (Gaxun Nur Basin) constitutes the endorheic erosion base of the drainage system. The basin - hosting the second largest continental alluvial fans in the world, is tectonically strongly shaped by the Gobi belt of left-lateral transpression. The tectonic setting in combination with competing climatic driving forces (Westerlies and summer/winter monsoon currents) has supported the formation of a valuable long-time sediment archive comprises at least the last 250,000 yrs. of deposition. It is composed by the interplay of eolian, fluvial and lacustrine sedimentation cycles and today is dominated by widespread (gravel) gobi surfaces, insular dune fields and shallow evaporitic playa areas. Thus, it provides excellent conditions to investigate tectonic evolution and Quaternary environmental changes. Recently, geomorphological, geophysical, neotectonic and mineralogical studies have enhanced the understanding of the environmental history and the modern depositional environment. Moreover, the role of the Hei River Basin as an important source area of silt particles which were later deposited on the Chinese Loess Plateau is evaluated. Therefore, a 230 m long drill core, sediment sections and ca. 700 surface samples throughout the whole catchment and basin were analyzed. Instrumental and historical seismicity are very low, but the proximity to active fault zones and dating irregularities in earlier publications indicate evidence for deformation in the study area. Despite flat topography, indications of active tectonics such as fault-related large-scale lineations can be observed. Seismically deformed unconsolidated lacustrine deposits (seismites), presumably of Holocene age, are evident and must be related to the nearby faults. The upper catchment is represented by the Qilian Shan mountain range and its immediate foreland. Here, a tripartite altitudinal distribution of terrestrial sediment archives is evident, which is representative of catchment-wide sedimentological processes. Insights into their formation mechanisms, therefore, add valuable perspective regarding the reconstruction of sedimentological and paleoenvironmental conditions in the depositional area of the Hei River Basin. For the characterization of provenance and dispersal of Quaternary sediments in relation to the modern depositional environment, over 200 surface samples from the whole catchment were analyzed using XRD and XRF measurements on the clay fractions, heavy minerals and bulk sediments. The clay mineral results in-particular show that it is possible to discriminate between the chlorite rich metamorphic sediments originating from greenschist bearing rocks in the Qilian Shan Mountain Range in the south, and the more intrusive rocks from the Bei Shan Mountain Range west of the Hei River Basin. Additionally, these two main sources reflect different transportation processes; the Qilian Shan sediments are mainly transported by the rivers Heihe and Beida He, and the deposition of the Bei Shan sediments is mainly driven by wind or local runoff. Grain size results of primary loess deposits indicate different eolian transport pathways, i.e., far-travelled dust input (medium silty) vs. local deflation from active fluvial channels (fine sandy). Along the altitudinal transect, the varying geomorphological settings exert a significant influence on the grain size composition showing an increased contribution of far-travelled dust at higher altitudes.

Rudersdorf, Andreas; Nottebaum, Veit; Schimpf, Stefan; Yu, Kaifeng; Hartmann, Kai; Stauch, Georg; Wünnemann, Bernd; Reicherter, Klaus; Diekmann, Bernhard; Lehmkuhl, Frank

2014-05-01

304

Geochemical soil sampling for deeply-buried mineralized breccia pipes, northwestern Arizona  

USGS Publications Warehouse

Thousands of solution-collapse breccia pipes crop out in the canyons and on the plateaus of northwestern Arizona; some host high-grade uranium deposits. The mineralized pipes are enriched in Ag, As, Ba, Co, Cu, Mo, Ni, Pb, Sb, Se, V and Zn. These breccia pipes formed as sedimentary strata collapsed into solution caverns within the underlying Mississippian Redwall Limestone. A typical pipe is approximately 100 m (300 ft) in diameter and extends upward from the Redwall Limestone as much as 1000 m (3000 ft). Unmineralized gypsum and limestone collapses rooted in the Lower Permian Kaibab Limestone or Toroweap Formation also occur throughout this area. Hence, development of geochemical tools that can distinguish these unmineralized collapse structures, as well as unmineralized breccia pipes, from mineralized breccia pipes could significantly reduce drilling costs for these orebodies commonly buried 300-360 m (1000-1200 ft) below the plateau surface. Design and interpretation of soil sampling surveys over breccia pipes are plagued with several complications. (1) The plateau-capping Kaibab Limestone and Moenkopi Formation are made up of diverse lithologies. Thus, because different breccia pipes are capped by different lithologies, each pipe needs to be treated as a separate geochemical survey with its own background samples. (2) Ascertaining true background is difficult because of uncertainties in locations of poorly-exposed collapse cones and ring fracture zones that surround the pipes. Soil geochemical surveys were completed on 50 collapse structures, three of which are known mineralized breccia pipes. Each collapse structure was treated as an independent geochemical survey. Geochemical data from each collapse feature were plotted on single-element geochemical maps and processed by multivariate factor analysis. To contrast the results between geochemical surveys (collapse structures), a means of quantifying the anomalousness of elements at each site was developed. This degree of anomalousness, named the "correlation value", was used to rank collapse features by their potential to overlie a deeply-buried mineralized breccia pipe. Soil geochemical results from the three mineralized breccia pipes (the only three of the 50 that had previously been drilled) show that: (1) Soils above the SBF pipe contain significant enrichment of Ag, Al, As, Ba, Ga, K, La, Mo, Nd, Ni, Pb, Sc, Th, U and Zn, and depletion in Ca, Mg and Sr, in contrast to soils outside the topographic and structural rim; (2) Soils over the inner treeless zone of the Canyon pipe show Mo and Pb enrichment anf As and Ga depletion, in contrast to soils from the surrounding forest; and (3) The soil survey of the Mohawk Canyon pipe was a failure because of the rocky terrane and lack of a B soil horizon, or because the pipe plunges. At least 11 of the 47 other collapse structures studied contain anomalous soil enrichments similar to the SBF uranium ore-bearing pipe, and thus have good potential as exploration targets for uranium. One of these 11, #1102, does contain surface mineralized rock. These surveys suggest that soil geochemical sampling is a useful tool for the recognition of many collapse structures with underlying ore-bearing breccia pipes. ?? 1994.

Wenrich, K. J.; Aumente-Modreski, R. M.

1994-01-01

305

Vertical distribution of radiocaesium, plutonium and americium in the Catalan Sea (northwestern Mediterranean)  

Microsoft Academic Search

Caesium-137, 239,240Pu and 241Am concentration profiles (0–1000m) have been determined in unfiltered large volume water samples collected from the Catalan Sea (northwestern Mediterranean). Results showed that radiocaesium concentration decreases quickly through the water column while the transuranic concentration increases with depth, showing a faster migration to the bottom layers. Comparing our results with those reported by other authors (1975–1980), radiocaesium

J. Molero; J. A. Sanchez-Cabeza; J. Merino; L. L. Pujol; P. I. Mitchell; A. Vidal-Quadras

1995-01-01

306

Marine Magnetic Anomaly and Magnetization of Oceanic Plate around the Japan Trench in the Northwestern Pacific  

Microsoft Academic Search

We have newly collected dense magnetic data around the Japan Trench in the northwestern Pacific. We present characteristics of the complied magnetic anomaly and crustal magnetization variation. The Pacific Plate in the study area has a series of parallel magnetic anomalies (Japanese Lineation Set), identified as chron M14-M7 (140-127 Ma). These anomalies are well lineated, in the direction of WSW-ENE,

T. Fujiwara; A. Obi; Y. Noda; Y. Kido; M. Nakanishi; N. Hirano; N. Abe; Y. Ogawa

2005-01-01

307

Tectonic implications of a late Mesozoic fold and thrust belt in northwestern Nevada  

Microsoft Academic Search

The Luning-Fencemaker fold and thrust belt of northwestern Nevada formed east of the Mesozoic Sierran arc in a back-arc setting where noncontinental crust localized marine deposition and subsequent deformation. The fold-thrust belt was active in Middle or Late Jurassic and Early Cretaceous time and evolved during major northwest-southeast contraction. Comparable shortening was not developed in the Sierran arc, and for

John S. Oldow

1983-01-01

308

Preliminary Results of Seismic Refraction\\/Reflection Experiment in Northwestern Nevada and Northeastern California  

Microsoft Academic Search

In September 2004, Stanford University is conducting a 260-km seismic refraction\\/reflection experiment across the northwestern margin of the Basin and Range Province between Winnemucca, Nevada and Alturas, California. This area was the locus of intense mid-Miocene (c. 17-15 Ma) volcanism and subsequent high-angle extensional faulting, and is often thought to be the breakout region of the Yellowstone hotspot. Today the

J. P. Colgan; D. L. Lerch; E. M. Gashawbeza; C. K. Wilson; S. L. Klemperer; E. L. Miller

2004-01-01

309

Geology of the Gerlach--Hualapai Flat geothermal area, northwestern Nevada  

Microsoft Academic Search

The 500-square mile (1,280 square km) area around Gerlach and Hualapai Flat in northwestern Nevada includes Permo-Triassic metavolcanic and metasedimentary rocks disposed as roof pendants in Cretaceous granodiorite, Late Oligocene-Early Miocene rhyolitic, andesitic, and basaltic sequences, and Pliocene (.) and Quaternary alluvial and lacustrine sediments. The volcanic activity is far too old (23 my) to act as a source of

L. T. Grose; R. J. Sperandio

1978-01-01

310

Habitat and reef-fish assemblages of banks in the Northwestern Hawaiian Islands  

Microsoft Academic Search

The moderately deep terraces and banks of the Northwestern Hawaiian Islands (NWHI) were surveyed to describe their habitat and reef-fish assemblages. These tracts of bottom at 30–40 m comprise more than 4,500 km 2of the region’s reef area. The habitat was found to be dominated by algal meadows (65% cover of exposed bottom), with infrequent relief features. Annual monitoring of select stations

Frank A. Parrish; Raymond C. Boland

2004-01-01

311

New hydrocarbon exploration areas in footwall covered structures in northwestern margin of Junggar Basin  

Microsoft Academic Search

The fold-and-thrust belt in the northwestern margin of the Junggar Basin is composed of the northern monocline belt, the middle syncline belt, the Ke-Wu thrust belt, and the frontal slope belt, and is divided into the upper and lower structural layers in vertical. The upper structural layer precedes the lower one in terms of thrust sequence. Inferred from the restoration

Shu-wei GUAN; Ben-liang LI; Lian-hua HOU; Deng-fa HE; Xin SHI; Yue-qian ZHANG

2008-01-01

312

Reproductive success of wild Lesser Rheas ( Pterocnemia Rhea pennata pennata ) in north-western Patagonia, Argentina  

Microsoft Academic Search

We studied the reproductive success of a wild Lesser Rhea population (Pterocnemia -Rhea- pennata pennata) during two reproductive seasons (2004\\/2005 and 2005\\/2006) in north-western Patagonia, Argentina. The parameters recorded\\u000a included population and nest density, clutch size, hatching success, chick survival (up to 3 months of age) and percentage\\u000a of chicks that reached the juvenile stage after the winter. We also

Fernando R. Barri; Monica B. Martella; Joaquín L. Navarro

2009-01-01

313

The flavonoid glycosides of Cornus canadensis L. and its allies in Northwestern North America  

Microsoft Academic Search

Summary The flavonoid glycoside profile ofCornus canadensis L. and its allies in Northwestern North America has been determined; quercetin 3-O-glucoside, 3-O-galactoside, 3-O-sophoroside and 3-O-gentiobioside; kaempferol 3-O-glucoside and 3-O-arabinoside. The discontinuity in distribution pattern of quercetin 3-O-gentiobioside within these taxa, associated with the phytogeography and historical factors affecting plant distribution in this area, indicates a possible polytopic and polychronistic origin of

J. F. Bain; K. E. Denford

1979-01-01

314

Net primary productivity of two mangrove forest stands on the northwestern coast of Sri Lanka  

Microsoft Academic Search

Productivity studies were carried out from September, 1985 to August, 1987 in two mangrove stands, i.e. estuarine and island fringing, in Dutch bay, a lagoon situated on the northwestern coast of Sri Lanka. Net above-ground primary productivity was measured by monitoring litterfall and above-ground biomass increment. The average annual rate of litterfall in the estuarine and island-fringing mangrove stands are

M. D. Amarasinghe; S. Balasubramaniam

1992-01-01

315

Draft Genome Sequence of Enterococcus faecium Strain CRL 1879, Isolated from a Northwestern Argentinian Artisanal Cheese  

PubMed Central

We report the draft genome sequence of the bacteriocin producer Enterococcus faecium strain CRL 1879, isolated from a northwestern Argentinian artisanal cheese. The draft genome sequence is composed of 73 contigs for 2,886,747 bp, with 3,140 protein-coding genes. Six biosynthetic clusters for bacteriocin class II production were found. Typical virulence determinants, which have relevance in food safety, were not present.

Suarez, Nadia E.; Saavedra, Lucila; Slozilova, Ivana; Bonacina, Julieta; Demnerova, Katerina

2013-01-01

316

Spatio-temporal variation of stable isotopes in precipitation in the Heihe River Basin, Northwestern China  

Microsoft Academic Search

An intensive investigation of the spatial and temporal variations of ?D and ?\\u000a 18O in precipitation was conducted during 2002–2004 in six sites in the Heihe River Basin, Northwestern China. The ?D and ?\\u000a 18O values for 301 precipitation samples ranged from +59 to ?254 and +6.5 to ?33.4‰, respectively. The relationship between\\u000a ?D and ?\\u000a 18O defines a well-constrained

Jinkui Wu; Y. Ding; B. Ye; Q. Yang; X. Zhang; J. Wang

2010-01-01

317

Blackfoot Indian utilization of the flora of the northwestern great plains  

Microsoft Academic Search

The Blackfoot Indians occupied the northwestern plains along and adjacent to the eastern base of the Rocky Mountains in present-day\\u000a southern Alberta, Canada, and western Montana, V. S. A. Climate and topography and, hence, vegetation of the region are diverse.\\u000a Although primarily meat-eaters, the Blackfoot consumed some vegetable foods. They had a knowledge of plant medicines, which\\u000a they used in

Alex Johnston

1970-01-01

318

On the generation and evolution of internal solitary waves in the northwestern South China Sea  

Microsoft Academic Search

Recently, internal solitary waves (ISWs) were observed from remote sensing images of the northwestern South China Sea (SCS). Scrutinizing the crests of these ISWs, it was suggested that they were generated locally as a result of tide–topography interaction. To confirm this assumption, a 2-D, fully nonlinear, non-hydrostatic Massachusetts Institute of Technology general circulation model (MITgcm) was applied to investigate the

D. Li; X. Chen; A. Liu

2011-01-01

319

A Holocene paleosecular variation record from the northwestern Barents Sea continental margin  

Microsoft Academic Search

A high-resolution paleomagnetic and rock magnetic study has been carried out on sediment cores collected in glaciomarine silty-clay sequences from the continental shelf and slope of the southern Storfjorden trough-mouth fan, on the northwestern Barents Sea continental margin. The Storfjorden sedimentary system was investigated during the SVAIS and EGLACOM cruises, when 10 gravity cores, with a variable length from 1.03

Leonardo Sagnotti; Patrizia Macrì; Renata Lucchi; Michele Rebesco; Angelo Camerlenghi

2011-01-01

320

TAXONOMIC STUDIES ON THE VEGETABLE PEST OF GENUS PLUTELLA SCHRÄNK (PLUTELLIDAE: LEPIDOPTERA) FROM NORTHWESTERN INDIA  

Microsoft Academic Search

Taxonomic studies of Plutella xylostella Linnaeus from northwestern India was made based on the structural details of wing venation and external genitalia. ABBREVIATIONS IA+2A - Vein representing fused first and second anal vein; 3A - Third anal vein; CuA1 - First anterior cubital vein; CuA2 - Second anterior cubital vein; CuP - Posterior cubital vein; FRI - Forest Research Institute;

P. C. Pathania; H. S. Rose

321

Ethnobotany of the Tacana: Quantitative inventories of two permanent plots of Northwestern Bolivia  

Microsoft Academic Search

We present ecological and ethnobotanical descriptions of two permanent 1-ha plots located in Amazonian forest near two Tacana\\u000a communities situated north and west of the Madidi National Park in the Iturralde Province, Department of La Paz of northwestern\\u000a Bolivia. We interviewed 13 Tacana men and women to identify and enumerate uses of all of the trees, palms, and lianas ?

Saara J. DeWalt; GeneviÈve Bourdy; Lia R. ChÁvez de Michel; Celin Quenevo

1999-01-01

322

Stem taper functions for maritime pine ( Pinus pinaster Ait.) in Galicia (Northwestern Spain)  

Microsoft Academic Search

A total of 31 taper functions from 3 different groups of models (single, segmented and variable-form taper functions) were\\u000a fitted to diameter-height data from 203 Pinus pinaster trees sampled across even-aged stands in Galicia (northwestern Spain). Most of the taper functions analyzed showed problems\\u000a of multicollinearity as indicated by the condition number. A second-order autoregressive CAR(2) error process was incorporated

A. Rojo; X. Perales; F. Sánchez-Rodríguez; J. G. Álvarez-González; K. von Gadow

2005-01-01

323

Aquatic invertebrates of Lake Gregory, northwestern Australia, in relation to salinity and ionic composition  

Microsoft Academic Search

Lake Gregory is a large semi-permanent lake system in arid north-western Australia. Its catchment extends into humid areas\\u000a and as a result the lake has dried only twice in the last 25 years. Although the system is mostly fresh, parts of it become\\u000a saline as they dry. We identified aquatic invertebrates and undertook chemical analysis of water samples from several

S. A. Halse; R. J. Shiel; W. D. Williams

1998-01-01

324

Morphological analysis of alpine communities of the north-western Caucasus  

Microsoft Academic Search

The species composition of four alpine communities in the north-western Caucasus was subjected to a morphological analysis.\\u000a The communities are an alpine lichen heath type (ALH), aFestuca varia grassland type (FVG), aGeranium-Hedysarum meadow type (GHM) and a snowbed community (SBC). Eighty-two species were studied, using the following morphological parameters:\\u000a vegetative mobility, presence of rosettes, architectural model, life form according toRaunkiaer

Galina A. Pokarzhevskaya

1995-01-01

325

Scanning electron microscopy of Pleistocene sands from Yamal and Taz peninsulas, Ob River Estuary, northwestern Siberia  

Microsoft Academic Search

Coastal sediments in the Ob River Estuary of northwestern Siberia are considered to have either glacial and\\/or estuarine\\/alluvial origins. One school of thought argues for interconnected ice domes on the continental shelf that linked the Fenno-Scandinavian and Siberian ice (Grosswald Thesis). Another school of thought argues for an estuarine\\/alluvial origin (Danilov-Vtyermin thesis). The key to solving the problem of the

William C. Mahaney

1998-01-01

326

Methane-derived carbonates and authigenic pyrite from the northwestern Black Sea  

Microsoft Academic Search

Methane seeps in the northwestern Black Sea are accompanied by carbonate and pyrite precipitates. Sediments were sampled at locations on the Romanian (120m depth) and Ukrainian (180–200m depth) shelf and slope. Layered carbonate crusts are formed of (i) carbonate-cemented siliciclastic sediment containing dreissenoid bivalves, (ii) microcrystalline high-Mg-calcite or aragonite, and (iii) aragonitic cement. The Dreissena sediment is subrecent and was

J Peckmann; A Reimer; U Luth; C Luth; B. T Hansen; C Heinicke; J Hoefs; J Reitner

2001-01-01

327

Effects of the winter of 1976-1977 on the northwestern sargasso sea.  

PubMed

A survey was conducted in the northwestern Sargasso Sea during the spring to assess the effect and extent of the winter cooling of 1976 to 1977 on the ocean. Newly formed, well-mixed layers of 18 degrees C water as deep as 550 meters were observed. The main thermocline south of the Gulf Stream was 100 to 150 meters deeper than it is on the average, which implies significant changes in the baroclinic transports. PMID:17755361

Leetmaa, A

1977-10-14

328

Seismites in Late Pleistocene and Holocene deposits of the northwestern Kola region ( northern Baltic Shield)  

Microsoft Academic Search

New data on soft-sediment deformation in Late Pleistocene and Holocene deposits of the northwestern Kola Peninsula (Pechenga River valley) are reported and analyzed in terms of paleoseismicity implications. Soft-sediment deformation is assigned to paleoseismic triggers on the basis of special criteria. One sedimentary section in the Pechenga valley bears signature of several seismic events at the Late Pleistocene–Holocene boundary, constrained

S. B. Nikolaeva

2009-01-01

329

Magnoliid reproductive organs from the Cenomanian-Turonian of north-western Kazakhstan: Magnoliaceae and Illiciaceae  

Microsoft Academic Search

Cenomanian-Turonian sediments from the Sarbay locality in north-western Kazakhstan have yielded a rich assemblage of plant fossils including well preserved flowers, fruits, and seeds of angiosperms. This work describes fossil seeds assigned to theMagnoliaceae and theIlliciaceae. Three new species of the extinct magnoliaceous genusLiriodendroidea, L. asiatica, L. costata, andL. tenuitesta, are established and new information on the previously described species,L.

S. Frumin; E. M. Friis

1999-01-01

330

Water Scarcity and Water Use in Economic Systems in Zhangye City, Northwestern China  

Microsoft Academic Search

Water has traditionally been considered a physically scarce resource in Northwestern China, and most investigations of water\\u000a scarcity focus on the finite nature of water supplies. Based on the input–output analysis, this paper establishes a number\\u000a of indicators of water consumption to analyze the structural relationships between economic activities and their physical\\u000a relationships with the water resources. These indicators allow

Yong Wang; Hong-lang Xiao; Rui-fang Wang

2009-01-01

331

Identification and molecular characterization of Theileria sp. infecting red deer ( Cervus elaphus ) in northwestern Poland  

Microsoft Academic Search

Piroplasms from Theileria genus were detected in blood and spleen of red deer Cervus elaphus culled during the months of September 2004–January 2005 in northwestern Poland. The polymerase chain reaction revealed the\\u000a presence of Theileria deoxyribonucleic acid in 88% (36 of 41) of the animals examined. Molecular characterization of the parasites based on large\\u000a piece of 18S ribosomal ribonucleic acid

Marek Sawczuk; Agnieszka Maciejewska; Bogumi?a Skotarczak

2008-01-01

332

High-frequency fluxes of labile compounds in the central Ligurian Sea, northwestern Mediterranean  

Microsoft Academic Search

Sinking particles were collected every 4h with drifting sediment traps deployed at 200m depth in May 1995 in a 1-D vertical system during the DYNAPROC observations in the northwestern Mediterranean sea. POC, proteins, glucosamine and lipid classes were used as indicators of the intensity and quality of the particle flux. The roles of day\\/night cycle and wind on the particle

M. Goutx; A. Momzikoff; L. Striby; V. Andersen; J. C Marty; I. Vescovali

2000-01-01

333

Was the Coppermine Homocline of northwestern Canada uplifted as part of a Middle Proterozoic forebulge  

SciTech Connect

Application of the principles of elastic plate bending to subsurface geometric information and outcrop in northwestern Canada suggests that Proterozoic crust was loaded and deflected during orogenic activity between about 1.6 and 1.1 Ga. Exposed Hudsonian (ca. 1.8-2.0 Ga) basement separating younger but coeval stratigraphic sequences in the Coppermine Homocline on the west and Bathurst Inlet on the east can be explained as a forebulge associated with the loading.

Cook, F.A. (Univ. of Calgary, Alberta (Canada))

1991-01-01

334

Bedrock incision, rock uplift and threshold hillslopes in the northwestern Himalayas  

Microsoft Academic Search

The topography of tectonically active mountain ranges reflects a poorly understood competition between bedrock uplift and erosion. Dating of abandoned river-cut surfaces in the northwestern Himalayas reveals that the Indus river incises through the bedrock at extremely high rates (2-12 mm yr-1). In the surrounding mountains, the average angles of hillslopes are steep and essentially independent of erosion rate, suggesting

Douglas W. Burbank; John Leland; Eric Fielding; Robert S. Anderson; Nicholas Brozovic; Mary R. Reid; Christopher Duncan

1996-01-01

335

Population genetic structure of the neon damselfish ( Pomacentrus coelestis ) in the northwestern Pacific Ocean  

Microsoft Academic Search

The population genetic structure of the neon damselfish (Pomacentrus coelestis) in the northwestern Pacific Ocean was revealed by the hypervariable control region of the mitochondrial gene (343 bp). In\\u000a total, 170 individuals were sampled from 8 localities distributed between Taiwan and Japan, and 71 haplotypes were obtained\\u000a through sequence alignment. High haplotype diversity (h = 0.956 ± 0.008) with low nucleotide diversity (? = 0.010 ± 0.006) was observed,

Shang-Yin V. Liu; Tomoyuki Kokita; Chang-Feng Dai

2008-01-01

336

The oceanic crustal structure of the Northwestern Subbasin in the South China Sea  

NASA Astrophysics Data System (ADS)

The oceanic crustal structure of the Northwestern Sub-basin (NWSB) area in the South China Sea (SCS) was inverted using wide-angle seismic survey line data across the entire region and on both sides of its bounding continental margin. The survey line extended 484 km in length. A total of 14 Ocean Bottom Seismometers (OBS) were deployed at intervals of 30 km, with a volume of the combined gun array of 5160 in3. The crustal velocity structure of the northwestern sub-basin area was acquired through integration of multi-channel seismic data. OBS data were processed and modeled initially using ray tracing inversion techniques. Results indicate that crustal thickness under the continental slope decreases from 21 km to 11 km, crustal thickness of NWSB is 7.7 km, and the depth to the Moho ascends from 21 km under the upper continental slope to 11 km under the middle basin. The oceanic crustal structure of NWSB is similar to that the Eastern Sub-basin (ESB). This oceanic structure has a thicker layer 1 (sedimentary layer) and thinner layer 2. These characteristics are especially clear in ESB, which differs somewhat from typical oceanic crustal structure. Because the seafloor spreading period of the northwestern sub-basin was short, layer 2 might have experienced asymmetrical basalt magma flows, which may have blurred the magnetic anomaly lineations of the northwestern sub-basin. By comparing with the oceanic crustal structure of the OBS survey line near Liyue Bank, we suggest that these two lines could be conjugate pair. Acknowledgements This study was supported by the National Key Basic Research Project of China (Grant No. 2007CB411701), Scientific Research Fund of the Second Institute of Oceanography, SOA(Grant No. JT1101), Key Laboratory of Marginal Sea Geology, Chinese Academy of Sciences (Grant No.MSGL09-07).

Wu, Z.; Li, J.; Ruan, A.; Ding, W.; Zhang, T.; Niu, X.

2011-12-01

337

Relationship between soil physiochemistry and land degradation in the lower Heihe River basin of northwestern China  

Microsoft Academic Search

Monitoring of soil-water physiochemistry (pH, total salt content, ion types, and ion ratios) across the lower Heihe River\\u000a basin of northwestern China indicated that the distribution of different soil hydrochemical types typically correlated with\\u000a that of different levels of soil desertification, specifically: 1) lands with the potential for desertification showed a Cl?-SO42?-Na+-Mg2+ soil-water ion complement, 2) those under on-going desertification

Qi Feng; Wei Liu; Haiyang Xi

2009-01-01

338

Patterns of use and damage by exotic deer on native plant communities in northwestern Patagonia  

Microsoft Academic Search

Ungulate overabundance can strongly alter composition and structure of forest communities through selective damage independently\\u000a of the herbivory history of the recipient system. In the early 1900s, red and fallow deer (Cervus elaphus and Dama dama, respectively) were introduced to northwestern Patagonia. We studied patterns of relative habitat use, damage, and species\\u000a selection by introduced deer populations in three major

M. Noelia Barrios-Garcia; M. Andrea Relva; Thomas Kitzberger

339

Petroleum systems of the northwestern Tachira Depression, Venezuelan Andes  

SciTech Connect

The tectonic evolution and sedimentation of the Tachira Depression was controlled by Paleozoic crustal scale discontinuities, partly or fully inverted during the pre-Andean (Paleocene) and Andean (Neogene) deformations. Outcrop samples were analyzed for source rock evaluation. La Luna, Los Cuervos and Carbonera formations are excellent potential oil sources. However, La Luna and Los Cuervos were the oil-generating units according to ID-modelling (BasinMod), defining La Luna-K/T(!) and Los Cuervos-K/T(!) systems. La Luna contains good to excellent oil prone kerogen type I-II, while Los Cuervos contains gas-oil prone type II-III. Oil seeps, expelled at the peak of oil generation stage (0.85-0.90 %R{sub o}), were derived from marine sources and genetically correlated to La Luna. No correlation of seeps with Los Cuervos was found. Although it exists to the southeast (Burgua depression). Potential clastic and carbonatic Cretaceous (K) and Tertiary (T) reservoirs and regional seals of the Colon and Leon Formations are widespread in the depression. Modelling results indicate that migration started during the Middle Miocene, related to the Andean tectonic loading. The subsequent migration took place northward, to be finally stopped against the Capacho and Bocono fault systems.

Ostos, M. [E.I.G. Litos C.A., Caracas (Venezuela); Callejon, A.; Vivan, M.A. [Corpoven, S.A., Puerto La Cruz (Venezuela)] [and others

1996-08-01

340

Satellite observations of surface circulation in the northwestern Gulf of Mexico during March and April 1989  

NASA Astrophysics Data System (ADS)

Six Argos-reported drifters drogued to a depth of 2.7 m produced eight trajectories over the Texas-Louisiana Shelf and the adjacent oceanic waters of the northwestern Gulf of Mexico from 7 March to 29 April 1989. Launched by United States Coast Guard aircraft and Texas A & M University's R.V. Gyre, the trajectories span the shelf from the vicinity of Barataria Bay, Louisiana to the southern reaches of Padre Island near Port Isabel, Texas. Two tracks demonstrate cross-slope and cross-shelf motion northward from the central western Gulf toward Louisiana. These two drifters join three others to define a coastal current flow westward from near the Mississippi delta to Galveston and then southwestward along the Texas coast. Two other trajectories indicate a relatively low-energy mid-shelf regime over the northwestern portion of the outer continental shelf. Five drifter groundings locate a convergence in the nearshore and littoral flows on the Texas coast between Matagorda Peninsula and southern Padre Island. Strong wind-driven events in the northwestern Gulf demonstrate instances of coherent shelf response over 7° of longitude and 3° of latitude. Infrared satellite imagery indicates the regional context and structure of the spatial scales of Gulf of Mexico surface circulation.

Barron, Charlie N.; Vastano, Andrew C.

1994-05-01

341

A late Jurassic pterosaur (Reptilia, Pterodactyloidea) from northwestern Patagonia, Argentina  

NASA Astrophysics Data System (ADS)

A small to medium-sized pterodactyloid pterosaur (wingspan approximately 1.10 m) from the Upper Jurassic (middle-late Tithonian) marine deposits of the Vaca Muerta Formation of Patagonia (Los Catutos area, central Neuquén Province, Argentina) is reported. The specimen lacks the skull but constitutes a nearly complete postcranial skeleton, which includes cervical and dorsal vertebrae; a few thoracic ribs; both pectoral girdles; the left pelvic girdle; a proximal right wing (humerus, ulna, and radius) and metacarpal IV; a left wing that lacks only wing phalanx four; and both hindlimbs, the right one without the foot. Ontogenetic features suggest that the new fossil corresponds to a relatively mature individual, probably a subadult. Observed characters support its assignment to the Archaeopteroactyloidea, a basal clade within the Pterodactyloidea. This specimen is the second pterosaur from Los Catutos and the most complete Jurassic pterosaur so far known from South America.

Codorniú, Laura; Gasparini, Zulma; Paulina-Carabajal, Ariana

2006-03-01

342

Cenozoic tectonic evolution of the basin and range province in northwestern Nevada  

USGS Publications Warehouse

A regional synthesis of new and existing geologic and thermochronologic data document late Cretaceous - early Cenozoic regional erosion, Oligocene - Miocene volcanism, and subsequent late Miocene extension of the Basin and Range Province in northwestern Nevada and northeastern California. Across an ???220-km-wide region between the Santa Rosa and Warner Ranges, conformable sequences of 35 to 15 Ma volcanic rocks are cut by only a single generation of high-angle normal faults that accommodated ???23 km of total east-west extension (???12%). Fission-track, (U-Th)/He, geologic, and structural data from the Pine Forest Range show that faulting there began at 11 to 12 Ma, progressed at a relatively constant rate until at least 3 Ma, and has continued until near the present time. Extension in the Santa Rosa Range to the east took place during the same interval, although the post-6 Ma part of this history is less well constrained. Less complete constraints from adjacent ranges permit a similar timing for faulting, and we infer that extensional faulting in northwestern Nevada began everywhere at 12 Ma and has continued up to the present. Faulting in the Warner Range in northeastern California can only be constrained to have begun between 14 and 3 Ma, but may represent westward migration of Basin and Range extension during the Pliocene. Compared to the many parts of the Basin and Range in central and southern Nevada, extension in northwestern Nevada began more recently, is of lesser total magnitude, and was accommodated entirely by high-angle normal faults. Fission-track data document Late Cretaceous unroofing of Cretaceous (115 - 100 Ma) granitic basement rocks in northwestern Nevada, followed by a long period of relative tectonic quiescence that persisted through Oligocene and Miocene volcanism until the onset of Basin and Range extension at ???12 Ma. The low magnitude of extension (12%) and early Tertiary stability suggest that the modern ???31 km thick crust in northwestern Nevada was only slightly thicker (???35 km) prior to extension at 12 Ma, and was no thicker than ???38 km in the Late Cretaceous. This stands in contrast to other parts of the Basin and Range, where the crust was thickened to at least 45 to 50 km by Cretaceous thrusting and subsequently thinned to ???30 km by large magnitude (>50%) extension.

Colgan, J. P.; Dumitru, T. A.; Reiners, P. W.; Wooden, J. L.; Miller, E. L.

2006-01-01

343

Touhuanping Fault, an active wrench fault within fold-and-thrust belt in northwestern Taiwan, documented by spatial analysis of fluvial terraces  

NASA Astrophysics Data System (ADS)

This study aims at the recent activity and development of an active wrench fault, the Touhuanping Fault in northwestern Taiwan. Northwestern Taiwan has been proposed in a current situation between the mature to waning collision in terms of tectonic evolution. The main drainage in this area, the Chungkang River, flows close to the trace of the fault mentioned above. We examined various types of deformation of fluvial terraces along the Chungkang River as a key to understanding the nature and rate of the late Quaternary tectonics. The E-W trending Touhuanping Fault has long been mapped as a geological boundary fault, but its recent activity was suspected. Field survey revealed that its late Quaternary activity is recorded in the offset fluvial terraces. Our result shows dextral slip and vertical offset with upthrown side on the south, and activated at least twice since the emergence of terrace 4 (older terrace 3 with OSL date of ca. 80 ka). Total amount of offset recorded in the Touhuanping terrace sequence is 15 m for dextral and 10 m for vertical offset. Estimated recurrence time of earthquake rupture may be a few tens of thousand years. Uplift on the upthrown side of the Touhuanping Fault also resulted in the formation of drowned valleys which were graded to terrace 4. Other deformation features, such as back-tilting, westward warping, and a range-facing straight scarp, were also identified. A second-order anticline roughly parallel to the Touhuanping Fault is suggested to be the origin of the northward tilting on terrace 3; it could have resulted from a flower structure on the Touhuanping Fault at shallow depth. This may demonstrate that the buried segment of the Touhuanping Fault has also been active since 80 ka. In the northern study area, the westward warping at terrace 2 probably represents late Quaternary activity of another NE-SW trending Hsincheng Fault.

Ota, Yoko; Lin, Yu-Nung Nina; Chen, Yue-Gau; Matsuta, Nobuhisa; Watanuki, Takuya; Chen, Ya-Wen

2009-09-01

344

Glacial anticyclone recorded in Palouse loess of northwestern United States  

NASA Astrophysics Data System (ADS)

Climate simulations for the Last Glacial Maximum using general circulation models typically show a glacial anticyclone that produced an easterly wind anomaly south of the North American ice sheets. Evidence of this phenomenon has not been found in eolian sedimentary deposits that record surface wind patterns. Luminescence ages of loess and accompanying paleoecologic records from opal phytoliths and paleosol units across the Columbia Plateau, Washington State, United States, document a decrease, up to fivefold, in regional dust production and accumulation from 35 ka to 15 ka. This interval corresponds to simulations indicating that a glacial anticyclone weakened prevailing south-southwesterly winds that have shaped the eolian landscape of the Columbia Plateau since at least 75 ka. At the same time that the glacial anticyclone suppressed dust production and accumulation, enhanced cold and dry conditions resulted in soil formation dominated by intense bioturbation in periglacial steppe accompanied by shallow calcium carbonate precipitation. This is the first evidence from eolian deposits in North America verifying that the glacial anticyclone altered surface wind patterns and affected eolian systems during the Last Glacial Maximum.

Sweeney, Mark R.; Busacca, Alan J.; Richardson, Catherine A.; Blinnikov, Mikhail; McDonald, Eric V.

2004-08-01

345

Stratigraphy, depositional environments, and carbonate petrology of the Toroweap and Kaibab Formations (lower Permian), Grand Canyon region, Arizona  

NASA Astrophysics Data System (ADS)

Sediments deposited in northwestern Arizona during Late Leonardian and Early Guadalupian (Permian) were controlled chiefly by an arid climate and the tectonic setting. Eastward thrusting of eugeosynclinal rocks onto miogeosynclinal deposits during Middle Devonian to Early Mississippian had a major influence on shelf sedimentation. The Toroweap and Kaibab formations represent two such platform sequences of northwestern Arizona and southern Utah deposited during this phase of sedimentation. The Toroweap Formation is subdivided into three members and represents sediments deposited during initial transgression, maximum extent of the sea, and regression (Seligman, Brady Canyon, and Woods Ranch members respectively). The Fossil Mountain Member of the Kaibab Formation documents the most extensive phase of sedimentation for all members of the Toroweap and Kaibab formations. The Harrisburg Member documents the final phase of sedimentation at the close of the Paleozoic Era.

Clark, R. A.

346

Hydrogeology, water use, and simulation of flow in the High Plains aquifer in northwestern Oklahoma, southeastern Colorado, southwestern Kansas, northeastern New Mexico, and northwestern Texas  

USGS Publications Warehouse

The U.S. Geological Survey, in cooperation with the Oklahoma Water Resources Board, began a three-year study of the High Plains aquifer in northwestern Oklahoma in 1996. The primary purpose of this study was to develop a ground-water flow model to provide the Water Board with the information it needs to manage the quantity of water withdrawn from the aquifer. The study area consists of about 7,100 square miles in Oklahoma and about 20,800 square miles in adjacent states to provide appropriate hydrologic boundaries for the flow model. The High Plains aquifer includes all sediments from the base of the Ogallala Formation to the potentiometric surface. The saturated thickness in Oklahoma ranges from more than 400 feet to less than 50 feet. Natural recharge to the aquifer from precipitation occurs throughout the area but is extremely variable. Dryland agricultural practices appear to enhance recharge from precipitation, and part of the water pumped for irrigation also recharges the aquifer. Natural discharge occurs as discharge to streams, evapotranspiration where the depth to water is shallow, and diffuse ground-water flow across the eastern boundary. Artificial discharge occurs as discharge to wells. Irrigation accounted for 96 percent of all use of water from the High Plains aquifer in the Oklahoma portion of the study area in 1992 and 93 percent in 1997. Total estimated water use in 1992 for the Oklahoma portion of the study area was 396,000 acre-feet and was about 3.2 million acre-feet for the entire study area. Since development of the aquifer, water levels have declined more than 100 feet in small areas of Texas County, Oklahoma, and more than 50 feet in areas of Cimarron County. Only a small area of Beaver County had declines of more than 10 feet, and Ellis County had rises of more than 10 feet. A flow model constructed using the MODFLOW computer code had 21,073 active cells in one layer and had a 6,000- foot grid in both the north-south and east-west directions. The model was used to simulate the period before major development of the aquifer and the period of development. The model was calibrated using observed conditions available as of 1998. The predevelopment-period model integrated data or estimates on the base of aquifer, hydraulic conductivity, streambed and drain conductances, and recharge from precipitation to calculate the predevelopment altitude of the water table, discharge to the rivers and streams, and other discharges. Hydraulic conductivity, recharge, and streambed conductance were varied during calibration so that the model produced a reasonable representation of the observed water table altitude and the estimated discharge to streams. Hydraulic conductivity was reduced in the area of salt dissolution in underlying Permianage rocks. Recharge from precipitation was estimated to be 4.0 percent of precipitation in greater recharge zones and 0.37 percent in lesser recharge zones. Within Oklahoma, the mean difference between water levels simulated by the model and measured water levels at 86 observation points is -2.8 feet, the mean absolute difference is 44.1 feet, and the root mean square difference is 52.0 feet. The simulated discharge is much larger than the estimated discharge for the Beaver River, is somewhat larger for Cimarron River and Wolf Creek, and is about the same for Crooked Creek. The development-period model added specific yield, pumpage, and recharge due to irrigation and dryland cultivation to simulate the period 1946 through 1997. During calibration, estimated specific yield was reduced by 15 percent in Oklahoma east of the Cimarron-Texas County line. Simulated recharge due to irrigation ranges from 24 percent for the 1940s and 1950s to 2 percent for the 1990s. Estimated recharge due to dryland cultivation is about 3.9 percent of precipitation. The mean difference between the simulated and observed waterlevel changes from predevelopment to 1998 at 162 observation points in

Luckey, Richard L.; Becker, Mark F.

1999-01-01

347

Trace metal distributions in shelf waters of the northwestern Black Sea  

NASA Astrophysics Data System (ADS)

Measurements of dissolved and leachable particulate trace metals (Mn, Fe, Co, Pb, Cd, Zn, Cu and Ni) and total particulate Mn and Fe were made on seawater samples collected from the northwestern Black Sea during the EROS 2000 expedition conducted in July-August 1995. The investigation concentrated on waters of the shelf and shelf edge, but included one deeper water (1440 m) station. In the oxic layer of the deep station, the suspended particulate fractions of Mn and Fe were a major part of the total metal mass, consistent with the presence of the "Fine Particle Layer" which forms on the shelf and spreads all over the Black Sea with intensities decreasing from the coast. Dissolved and total particulate concentrations were, respectively, Mn, 0.69-9.6, 1.2-29; Fe, 0.79-3.03, 2.3-7.4 nM. Dissolved Cu and Ni concentrations were relatively high (1-8 and 8-12 nM, respectively), and did not show any depletion in surface oxic waters, possibly as a result of strong organic complexation. Dissolved Pb concentrations (100-200 pM) were higher than were generally found on the shelf. This was attributed to atmospheric inputs combined with less efficient scavenging of metals in these low SPM waters. The distribution of dissolved Co closely resembled that of dissolved Mn reflecting coupling through oxidation of Mn. Concentrations of dissolved Cd and Zn were low in surface water (0.07-0.09 and 0.9-2.0 nM, respectively), and increases in concentrations with depth were sharply reversed around the top of the redoxcline. For most metals (Mn, Fe, Co, Pb, Cu, Cd, Zn) dissolved concentrations were low in the anoxic layers as a result of solubility by formation of, or association with, solid sulphide phases. Dissolved Ni was not affected by sulphide precipitation. At most of the shelf stations there were clear enhancements of dissolved Mn and Fe in the deepest waters, consistent with other evidence that significant benthic fluxes of these metals arise through the redox conditions in the region of the sediment-water interface. In the shelf water column, dissolved Mn and Fe concentrations ranged between 1.2 and 1350 and between 0.4 and 181 nM, respectively; the highest concentrations were found near the bottom. Particulate concentrations of Mn and Fe were high, implying high oxidation rates of Mn(II) and Fe(II) and/or high supply rates from rivers. Total particulate concentrations of Mn and Fe were 0.7-1050 and 2.3-2650 nM, respectively; the highest concentrations were found in surface and bottom waters. The distributions of particulate Mn and Fe were consistent with the isopycnal transport of Mn and Fe oxyhydroxides from the shelf by the coastal circulation. Distributions of other trace metals (Co, Pb, Cu, Ni, Cd, Zn) were considerably influenced by riverine inputs. Relatively high dissolved and available particulate metal concentrations were generally found in surface waters at stations directly influenced by the Danube River. Some trace metals (Co, Ni, Cd and Zn) were influenced by Mn and Fe cycling and increases in their dissolved concentrations occurred at a number of stations near the sediment-water interface. Dissolved and available particulate metal concentrations (nM) at stations on the shelf were, respectively: 0.171-1.80, 0.003-0.437 (Co); 0.014-0.614, 0.010-1.48 (Pb); 7.6-28.8, 0.048-3.75 (Cu); 11.0-17.5, 0.018-2.10 (Ni); 0.033-0.161, 0.003-0.063 (Cd); 1.01-8.33, 0.135-7.58 (Zn).

Tankéré, S. P. C.; Muller, F. L. L.; Burton, J. D.; Statham, P. J.; Guieu, C.; Martin, J.-M.

2001-08-01

348

Bedout basement rise, offshore northwestern Australia: evidence of an unshocked mafic volcanic hyaloclastite volcanic breccia  

NASA Astrophysics Data System (ADS)

Core samples from Bedout-1 (3035.8-3044.95 m.), Bedout basement rise, offshore northwestern Australia, were examined by optical microscopy, SEM, EDS and WDS spectrometry. At this stratigraphic depth level Becker et al. (2004) interpret cryptocrystalline alteration zones around and within plagioclase in terms of shock-induced transformation of feldspar into diaplectic maskelynite glass _u postulating a ~200 km-large impact structure and thereby an impact connection of the Permian-Triassic boundary mass extinction. However, the breccia is dominated by fragments of microlitic basalt and ophitic-textured dolerite with well preserved igneous textures, showing no evidence of shock metamorphism. Euhedral pseudomorphs of chlorite and amphibole, probably after pyroxene, protrude into or are enveloped by euhedral albite-twinned calcic plagioclase (andesine to bytownite). Minor phases include euhedral ilmenite needles and subhedral magnetite grains. Plagioclase is altered by cryptocrystalline albite and microcrystalline albite-chlorite matrix along crystal boundaries, along twin lamella and within internal oscillatory crystal zones, consistent with burial metamorphosed hydrovolcanic basalts and spilites (e.g. Amstutz, 1974). The volcanic fragments are set within, and injected by, microcrystalline intergranular mesostasis of mixed mineral fragments and volcanic meta-glass. Becker et al. (2004) refer to the breccia in part as product of Mg-rich sediments (e.g. dolomites). However, apart from the pristine igneous textures of the breccia, the transition element levels (chlorite in dolerite fragment "C Ni 97-160 ppm; Co 75-152 ppm; Cu 69-204 ppm; mesostasis "C Ni 29-45 ppm; Co 18-52 ppm; Cu 26-110 ppm) are consistent with Fe-rich basalts but exceed common abundances in carbonates and marls (BVTP, 1981; Wedepohl, 1978). No shock metamorphic features, such as planar deformation features (PDF), are observed in the feldspar or in any other phases. No criteria for discriminating maskelynite and volcanic meta-glass are indicated by Becker et al. (2004). As PDF formation (10-35 GPa) necessarily precedes diaplectic transformation into maskelynite (35-45 GPa) (French, 1998), a presence of maskelynite is inconsistent with the absence of PDF in the plagioclase _u a phase prone to the development of shock effects (e.g. Mory, 2000). Little evidence exists for the hydrothermal activity which typically follows impact events. However, thanks to a partial development of a rim syncline-like structure in Triassic sediments around the Bedout rise, further testing of the origin of this remarkable structure is warranted. Amstutz, G.C., 1974, Spilites and Spilitic Rocks, Springer-Verlag, Berlin; Becker, L. et al., 2004, Science Express, 13.5.04; BVSP - Basaltic Volcanism Study Project, 1981, Pergamon; French, B.M., 1998, Traces of Catastrophe, Lunar and Planetary Contributions 954; Mory et al., 2000, Earth and Planetary Science, 177, 119-128; Wedepohl, K.H., Handbook of Geochemistry, Springer-Verlag, 1978.

Glikson, A.

2004-12-01

349

Late Cretaceous to Middle Eocene Geological Evolution of the Northwestern Caribbean - Constraints from Cuban Data  

NASA Astrophysics Data System (ADS)

Cuba acts as the northwestern boundary of the Caribbean Sea. However it is not part of the Caribbean plate, its geological development is deeply related to the plate history. In fact, its Cretaceous volcanic arc rocks tightly correlate with coeval sections in Hispaniola and Puerto Rico, and the same probably occurs with the ophiolites. The early Palaeogene events in Cuba were also involved in the Caribbean plate history. In general, two principal structural levels can be distinguished in the geological structure of Cuba. The rocks belonging to the upper level (Eocene to Quaternary) are little disturbed and can be referred to as the cover. Below it occurs the great complex of the Cuban orogenic belt, which consists mainly of rocks of Jurassic to Eocene age. In addition, small outcrops of Proterozoic metamorphic rocks also occur in north central Cuba. The Palaeocene-Eocene section contains volcanic arc sequences in SE Cuba and northward thrusted piggy back and foreland basins in central and western Cuba. The Mesozoic rocks lies unconformably below. The contacts between the major Mesozoic elements are always tectonic. With the exception of the rocks of the passive Mesozoic margin of North America in northern Cuba, the remaining units represent tectonostratigraphic terranes extending parallel to the axis of the present main island of Cuba. The northernmost unit is the Mesozoic passive continental margin of North America. It consists of a Jurassic- Cretaceous mainly marine sedimentary sequence now exposed as a thrust and fold belt along the northern edge of the Cuban mainland. The other units are, from north to south: the Northern Ophiolitic Belt, the Volcanic Arc Terrane and the Southern Metamorphic Terranes. The ophiolites and the Cretaceous volcanic arc terranes belong to the Proto-Caribbean plate and were accreted to the palaeomargin during Late Cretaceous and early Palaeogene episodes. Some constrains to Caribbean plate origin and evolution according to data from Cuba: Ophiolites: 1- The age of the rocks of the northern ophiolite belt is Upper Jurassic-Albian. Oceanic lithosphere formation, at least in the "Cuban" Proto-Caribbean, ended in the Albian. Cretaceous volcanic arcs: 2- At least two volcanic arc Cretaceous sections are present in Cuba, separated in several regions by a mainly sedimentary Albian-Cenomanian section. The lower arc is probably of Aptian-Albian age. The Cenomanian (or Turonian?) -Campanian upper arc is calcalkalic and contains abundant sedimentary marine interbeds. 3- Some thin tuff beds are present in the southernmost deep water deposits of the North American palaeomargin in western and central Cuba in the Aptian-Cenomanian. This fact could be explained by a volcanic arc located several hundred km to the south of the NA palaeomargin. 4- Cretaceous volcanism ended during the early Campanian all along Cuba. Sedimentary upper Campanian and Maastrichtian sections rest on top of the older Cretaceous sections. Volcanism is only reassumed in SE Cuba (Turquino volcanic arc) late in the Danian. Southern metamorphic terranes: 5- The southern metamorphic terranes are a main feature in the geology of Cuba. They are continental blocks sharing many stratigraphic features with the NA palaeomargin of western Cuba (Guaniguanico mountains). As the last one area seems related to the Yucatan (Maya) block, some authors consider the metamorphic terranes as fragments of the Maya block that travelled to the west.

Cobiella, J.; Hueneke, H.; Meschede, M.; Sommer, M.

2006-05-01

350

Costs of Nutrient Losses in Priceless Soils Eroded From the Highlands of Northwestern Ethiopia  

NASA Astrophysics Data System (ADS)

Soils formation is a geomorphic process that takes place through the interaction of soil forming factors in several hundreds and thousands of years. However, land degradation and soil erosion is consistently taking place in the horn of Africa washing away this priceless product in short period of time. The scale of the problem dramatically increased due to the increase in deforestation, overgrazing, over-cultivation, inappropriate farming practices, and increasing human population. Several research results were published in the region showing the extent of land degradation and soil loss. However, little attempt has been done to estimate the nutrient loss in monitory terms which made it difficult for policy makers to properly understand the extent of the problem. A study was, therefore, conducted in 2011 to estimate soil and nutrient losses caused by water erosion and predict nutrient replacement costs on different land use types and slope classes at Harfetay watershed, Northwestern Ethiopia. The revised soil loss equation (RUSLE) was used to estimate the soil loss from the different land uses and slope classes in watershed. Moreover, nutrient loss from similar units was calculated by multiplying the in situ nutrient concentration of soil samples by the estimated soil loss using RUSLE. The replacement costs of nutrient losses were calculated by multiplying the nutrient loss with the price of available nutrients in urea and diammonium phosphate. The estimate of the RUSLE indicated that the average soil losses in the study watershed were 119 tons ha-1 year-1 for non-conserved crop land, 23 tons for conserved farmlands, 23 tons for forest and shrub lands, 19 tons for grazing lands, and 6 tons for plantation forest. The mean soil loss for lower slope classes (<15%), middle slope classes (15-30%) and upper slope classes (>30%) were 30.11, 48.09 and 57.22 tons ha-1 year-1, respectively. The highest losses of total nitrogen (154.7 kg ha-1 year-1), available phosphorus (1.84 kg ha-1 year-1), and organic matter (1677.9 kg ha-1 year-1) were obtained from non-conserved cropland. Conversely, the lowest values of the same parameters were registered from the land covered with plantation forest. Comparing slope classes for non conserved cropland, organic matter and nutrient losses were higher in upper slope classes followed by middle and lower ones. The replacement cost of available N and available P for non-conserved cropland, conserved cropland, forest/shrub lands, grazing lands and plantations were 121, 36, 27, 32 and 13 Birr ha-1 year-1, respectively (1USD = 19 Birr); and the weighted mean replacement cost in the watershed was estimated to be 98 Birr ha-1 year-1 which is about 20% of the cost of fertilizer applied per individual farmers in the watershed. From the study it was possible to conclude that conversion of forest lands and plantation forests to cropland causes serious soil and nutrient losses. Construction of conservation structures on cropland, however, will reduce soil and nutrient losses. To halt soil and nutrient loss and ensure sustainable land management and agricultural development in the Harfetay watershed and similar watersheds, policy and development interventions including increasing awareness of farmers on of soil and nutrient losses, enforcing land use policies and expanding bio-physical soil conservation practices are required.

Gebreselassie, Yihenew; Belay, Yihenew

2014-05-01

351

What induced the exceptional 2005 convection event in the northwestern Mediterranean basin? Answers from a modeling study  

NASA Astrophysics Data System (ADS)

Open-sea convection occurring in the northwestern Mediterranean basin (NWMED) is at the origin of the formation of Western Mediterranean Deep Water (WMDW), one of the main Mediterranean water masses. During winter 2004-2005, a spectacular convection event occurred, observed by several experimental oceanographers. It was associated with an exceptionally large convection area and unusually warm and salty WMDW. Explanations were proposed tentatively, relating the unusual characteristics of this event to the Eastern Mediterranean Transient (EMT) or to the atmospheric conditions during winter 2004-2005 in the NWMED. They could, however, not be supported until now. Here we used numerical modeling to understand what drove this convection event. The control simulation performed for the period 1961-2006 reproduces correctly the long-term evolution of the Mediterranean Sea circulation, the EMT, and the NWMED convection event of 2004-2005. Sensitivity simulations are then performed to assess the respective contributions of atmospheric and oceanic conditions to this event. The weakness of the winter buoyancy loss since 1988 in the NWMED prevented strong convection to occur during the 1990s, enabling heat and salt contents to increase in this region. This resulted in the change of WMDW characteristics observed in 2005. The strong buoyancy loss of winter 2004-2005 was responsible for the intensity of the convection observed this winter in terms of depth and volume of newly formed WMDW. The EMT did not fundamentally modify the convection process but potentially doubled this volume by inducing a deepening of the heat and salt maximum that weakened the preconvection stratification.

Herrmann, Marine; Sevault, Florence; Beuvier, Jonathan; Somot, Samuel

2010-12-01

352

Geochemical, U-Pb zircon, and Nd isotope investigations of the Neoproterozoic Ghawjah Metavolcanic rocks, Northwestern Saudi Arabia  

NASA Astrophysics Data System (ADS)

New geochemical, Nd-isotope and U-Pb zircon data from Neoproterozoic volcanic rocks from Wadi Sawawin in northwestern Saudi Arabia provide important constraints on the evolution of the crust in this part of the Arabian-Nubian Shield (ANS). The Ghawjah volcanic rocks range from tholeiitic to calc-alkaline and are metamorphosed to greenschist facies. U-Pb zircon analyses for Ghawjah andesite yield a weighted mean 206Pb/ 238U age of 763 ± 25 Ma, indicating that these are some of the oldest rocks of the Midyan terrane. Ghawjah volcanic rocks are mostly moderately fractionated, as indicated by Mg-numbers between 28 and 67, Cr between 5 to 537 ppm and Ni from 4 to 175 ppm, REE patterns are slightly fractionated [(La/Yb)N = 1.2 to 4.0], and multi-element diagrams show Ba, Sr, Rb and K enrichments and Nb and Ta depletions, typical of modern convergent-margin igneous rocks. Ghawjah volcanic rocks have positive ?Nd (+ 5.4 to + 8.2) and a mean model age of 0.71 Ga. Ghawjah volcanic rocks are similar to the "Younger Volcanic" rocks from the Central Eastern Desert (CED) of Egypt, in terms of stratigraphic relations, chemical compositions, Nd-isotopic compositions, and U-Pb zircon ages (~ 750 Ma), indicating that both were generated by partial melting of subduction-modified depleted mantle. The Ghawjah volcanic rocks are interpreted to have formed at ~ 750 Ma in an arc setting during an important episode of crust formation.

Ali, Kamal A.; Stern, Robert J.; Manton, William I.; Kimura, Jun-Ichi; Whitehouse, Martin J.; Mukherjee, Sumit K.; Johnson, Peter R.; Griffin, William R.

2010-12-01

353

The basement of the Eastern Cordillera, Colombia: An allochthonous terrane in northwestern South America  

NASA Astrophysics Data System (ADS)

The fault system of the Borde Llanero of Colombia represents the limit between two early Paleozoic geologic provinces: the Guiana Shield (Gondwana) to the east, and an allochthonous terrane — formerly a piece of the North American continent — to the west. The Baudó Range, the Western Cordillera, and the western flank of the Central Cordillera are the result of post-Jurassic accretion. In contrast the pre-Emsian metamorphic rocks of the eastern flank of the Central Cordillera, of the Eastern Cordillera of Colombia, and of the Mérida Andes correspond to an allochthonous terrane that was accreted to the north-western continental border of South America during the collision between North America and Gondwana in Silurian-Early Devonian times. Geochronologic and petrographic data indicate the presence of the Grenvillian granulite belt, represented by the Garzón-Sierra Nevada de Santa Marta belt. This belt is separated from the Guiana Shield by a magmatic tract which is parallel to the Borde Llanero of Venezuela and Colombia. The late Paleozoic regional metamorphism in the Northern Andes of Colombia occurred during Late Silurian-Early Devonian times. Since the late Emsian, a sedimentary cycle was initiated on this allochthonous basement. The faunal records of northwestern South America and the North American continent are indistinguishable for that time. This similarity clearly shows that both northwestern South America and the North American regions of the Appalachians and New Mexico belong to the same paleobiogeographic province. The faunal communication in this case supports the idea of the immediate neighborhood of the two continents.

Forero Suarez, A.

354

Paleoseismic evidence of a surface rupture along the northwestern Himalayan Frontal Thrust (HFT)  

NASA Astrophysics Data System (ADS)

New paleoseismic evidence is presented from the Bhatpur (N 31°18'16.28?, E 76°9'50.00?) Trench site along the Himalayan Frontal Thrust (HFT) on western margin of the Janauri Anticline in NW Himachal Himalaya, India. The latest surface rupture at this site demonstrates coseismic displacement of at least 9.3 m. Radiocarbon dating of trench samples indicates that the surface ruptures occurred at A.D. 1400-1460. After comparison with other trench results along the Himalayan Front, two scenarios are presented of the latest surface rupturing earthquake event in the northwestern Indian Himalaya: (1) a single-event surface rupturing for a minimum fault length of 450 km, or (2) two-events of different lateral extent. According to the former scenario, the latest surface rupture occurred between A.D. 1404 and 1422. The latter scenario suggests the latest surface rupture occurred between A.D. 1404 and A.D. 1460 in the northwestern extent from Kala Amb to Hajipur with ~ 9.0 m of coseismic displacement over a minimum fault length of 200 km. Yet another surface rupture event in the southeastern extent from Kala Amb to Ramnagar has occurred between A.D. 1282 and A.D. 1422, with displacement ranging from 16.0 m to 26.0 m, and a minimum surface rupture length of 230 km. On the basis of these observations and historical earthquakes, it is suggested that the potential for earthquakes larger than those in the historical records are capable of producing surface-rupture lengths greater than the ~ 200 to ~ 230 km or ~ 450 km in the northwestern Indian Himalayan Front.

Kumahara, Yasuhiro; Jayangondaperumal, R.

2013-01-01

355

Climate change increases deoxynivalenol contamination of wheat in north-western Europe.  

PubMed

Climate change will affect the development of cereal crops and the occurrence of mycotoxins in these crops, but so far little research has been done on quantifying the expected effects. The aim of this study was to assess climate change impacts on the occurrence of deoxynivalenol in wheat grown in north-western Europe by 2040, considering the combined effects of shifts in wheat phenology and climate. The study used climate model data for the future period of 2031-2050 relative to the baseline period of 1975-1994. A weather generator was used for generating synthetic series of daily weather data for both the baseline and the future periods. Available models for wheat phenology and prediction of deoxynivalenol concentrations in north-western Europe were used. Both models were run for winter wheat and spring wheat, separately. The results showed that both flowering and full maturation of wheat will be earlier in the season because of climate change effects, about 1 to 2 weeks. Deoxynivalenol contamination was found to increase in most of the study region, with an increase of the original concentrations by up to 3 times. The study results may inform governmental and industrial risk managers to underpin decision-making and planning processes in north-western Europe. On the local level, deoxynivalenol contamination should be closely monitored to pick out wheat batches with excess levels at the right time. Using predictive models on a more local scale could be helpful to assist other monitoring measures to safeguard food safety in the wheat supply chain. PMID:22742589

van der Fels-Klerx, H J; Olesen, J E; Madsen, M S; Goedhart, P W

2012-01-01

356

Fatty acid composition of Yersinia ruckeri isolates from aquaculture ponds in northwestern Germany.  

PubMed

Enteric Redmouth Disease (ERM), caused by Yersinia (Y.) ruckeri is one of the most important diseases in salmonid aquaculture. Outbreaks of ERM were controlled by vaccines directed against motile strains of the bacterium, until recently nonmotile vaccine-resistant strains evolved and caused severe outbreaks. Non-motile isolates were found widespread in aquaculture populations in north-western Germany. In the present study, 82 Y. ruckeri isolates were isolated from trout hatcheries in North Rhine Westfalia, Lower Saxony and Hessen and only 20% of them were motile. In order to further characterise the Y. ruckeri isolates from fish aquaculture populations in north-western Germany, the fatty acid compositions of 82 Y. ruckeri field isolates from this area and of the Y. ruckeri reference strain DSM 18506 were analysed by gas chromatography. All Y. ruckeri isolates exhibited 15 major fatty acids, including 12:0, 13:0, 13.957 (equivalent chain length, ECL unknown), 14:0, 14.502 (ECL unknown), 15:0, 16:1omega5c, 16:0, 17:1omega8c, 17:0 CYCLO, 17:0, 16:1 2OH, 18:1omega9c, 18:1omega7c and 18:0. From a dendrogram, all isolates were close to one another, clustering together; while slight differences were detected among the isolates and the reference strain DSM 18506. Compared to their epidemiological and biochemical characteristics, there was no relationship found between the fatty acid profiles, API 20E profiles, motility and geographic distribution. Our results show that the fatty acid composition of Y. ruckeri isolates from north-western Germany is highly homogenous. PMID:24693657

Huang, Yidan; Ryll, Martin; Walker, Charles; Jung, Arne; Runge, Martin; Steinhagen, Dieter

2014-01-01

357

General characteristics and structural evolution of metamorphic goldquartz veins in northwestern Nevada, U.S.A  

Microsoft Academic Search

Metamorphic gold-quartz veins in northwestern Nevada, U.S.A. formed during both brittle and brittle-ductile shear deformations\\u000a in three tectono-stratigraphic terranes. The veins are concentrated in a 60- to 100-km-wide, 200-km-long, linear, northtrending\\u000a corridor. The veins show a consistent northeast strike in the central parts of the corridor and several kinematic indicators\\u000a strongly suggest that the broad corridor acted as a regional-scale

Sangwon Cheong

2000-01-01

358

Hydrologic data from Naval Oil Shale Reserves, Parachute Creek basin, northwestern Colorado, 1980-81  

USGS Publications Warehouse

Two years (water yr 1980 and 1981) of data collected by the U.S. Geological Survey for the U.S. Department of Energy, Naval Petroleum and Oil Shale Reserves, in the Parachute Creek drainage basin of northwestern Colorado are tabulated. Data were obtained from five surface water gages, two automatic sediment samplers, and two water quality monitors. Climate data include maximum, minimum, and average temperature and relative humidity, average wind speed and wind direction, and total daily solar radiation. Daily total precipitation is reported for three stations, and snow-course data reported for one site. (Author 's abstract)

Galyean, K. C.; Adams, D. B.; Collins, D. L.

1985-01-01

359

Caribou antlers as nest materials for golden eagles in northwestern Alaska  

USGS Publications Warehouse

There are few published records of antlers in golden eagle (Aquila chrysaetos) nests. This note reports extensive use of caribou (Rangifer tarandus) antlers in three golden eagle nests in the Cape Kruzenstern region of northwestern Alaska. The importance of antlers to this population of eagles can be explained at least in part by (1) the lack of suitable woody vegetation on the open tundra, (2) the similarity of antlers to sticks, and (3) the abundance of antlers, especially cow caribou antlers, in the region.

Ellis, D.H.; Bunn, R.L.

1998-01-01

360

Pathological features of Breast Cancer seen in Northwestern Tanzania: a nine years retrospective study  

Microsoft Academic Search

Background  Breast cancer is more common in Western Countries compared to African populations. However in African population, it appears\\u000a that the disease tends to be more aggressive and occurring at a relatively young age at the time of presentation. The aim\\u000a of this study was to describe the trend of Breast Cancer in Northwestern Tanzania.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  This was a retrospective study which

Peter F Rambau; Philipo L Chalya; Mange M Manyama; Kahima J Jackson

2011-01-01

361

Allele frequencies of 15 STRs in the Calchaqui Valleys population (North-Western Argentina).  

PubMed

Allele frequencies for 15 short tandem repeat (STR) loci were obtained from a sample of 110 individuals from the Calchaqui Valleys population (North-Western Argentina). The combined power of exclusion and combined power of discriminating for the 15 tested STR loci were 0.999964 and 0.9999999999999998, respectively. Matching probability was 1 in 4.58 × 10(15). Therefore, it may be concluded that the set of 15 STRs included in the AmpF STR Identifiler kit, represents a powerful tool for forensic applications, paternity testing and population genetics studies in the Calchaqui Valleys population. PMID:21641291

Muñoz, A; Albeza, M V; Acreche, N; Castro, J A; Ramon, M M; Picornell, A

2012-01-01

362

Ticks (Ixodidae) parasitizing humans in four provinces of north-western Argentina.  

PubMed

In four provinces of north-western Argentina (Catamarca, Jujuy, Salta and Tucumán), between March 1976 and March 1990, 514 ticks were found on humans. They were identified as Rhipicephalus sanguineus group (1 male), Boophilus microplus (6 male, 1 female), Amblyomma parvum (9 male, 13 female), A. cajannense (35 male, 30 female, 81 nymphs), A. neumanni (33 male, 41 female, 144 nymphs) and Amblyomma spp. (10 nymphs, 110 larvae). Most of the ticks were from the phytogeographical region of Chaco, one (B. microplus) was from an ecotone between the Chaco and the Andean Patagonia region, and the remainder of the ticks were from the Amazon region. PMID:1809248

Guglielmone, A A; Mangold, A J; Viñabal, A E

1991-10-01

363

Water-level maps of the alluvial aquifer, northwestern Mississippi, September 1982  

USGS Publications Warehouse

Water levels were measured in about 500 wells in the Mississippi River valley alluvial aquifer in northwestern Mississippi during September 13-24, 1982. The water-level change from September 1981 to September 1982 showed some recovery, but the depth-to-water map showed areas of continual water-level decline in the central part of the Delta. Water levels in the Delta were higher along the Mississippi River and Bluff Hills and Yazoo River. Historically, water levels decline and rise as the amount of precipitation decreases or increases. Recently, continuous heavy pumping for irrigation has caused general water-level declines in the alluvial aquifer. (USGS)

Darden, Daphne

1983-01-01

364

Water-level maps of the alluvial aquifer, northwestern Mississippi, September 1981  

USGS Publications Warehouse

Water levels were measured in 427 wells in the Mississippi River valley alluvial aquifer in northwestern Mississippi during the period September 15-28, 1981. Water levels in the alluvial sands and gravel were generally lower than water levels in September 1980 and larger depressions in the surface of the ground-water body were detected in the Sunflower-Leflore County area and in Humphreys County. These depressions are attributed to heavy pumping for irrigation and to less-than normal rainfall. Other smaller depressions are attributed to local heavy pumping. (USGS)

Darden, Daphne

1982-01-01

365

Water-level map of the Mississippi delta alluvium in northwestern Mississippi, April 1981  

USGS Publications Warehouse

Water levels were measured in 454 wells in the alluvial sediments in northwestern Mississippi during the period April 13-24, 1981. Ground-water levels are higher after winter and spring rains and lower after heavy agricultural and industrial pumping. Locally, water levels fluctuate as rivers and streams fluctuate. Because of the drought conditions in April 1981, most water wells had risen several feet. In some areas, however, water levels had not recovered from the relatively low levels measured in September 1980. (USGS)

Darden, Daphne

1981-01-01

366

Water-level maps of the alluvial aquifer northwestern Mississippi, April 1982  

USGS Publications Warehouse

Water levels were measured in about 500 wells in the Mississippi River valley alluvial aquifer in northwestern Mississippi during the period April 12-23, 1982. The water-level change from April 1981 to April 1982, showed a general decline, but the water-level change from September 1981 to April 1982 showed some recovery. Water levels in the Delta were higher along the Mississippi River and Bluff Hills. Historically, water levels decline and rise as the amount of precipitation decreases or increases. Recently, continuous heavy pumping for irrigation has caused general water-level declines in the alluvial aquifer. (USGS)

Darden, Daphne

1982-01-01

367

Catheter-related infections in a northwestern São Paulo reference unit for burned patients care.  

PubMed

Despite improvements in care and rehabilitation of burned patients, infections still remain the main complication and death cause. Catheter-related infections are among the four most common infections and are associated with skin damage and insertion site colonization. There are few studies evaluating this kind of infection worldwide in this special group of patients. Padre Albino Hospital Burn Care Unit (PAHBCU) is the only reference center in the Northwestern São Paulo for treatment of burned patients. This paper presents the results of a retrospective study aiming at describing the epidemiological and clinical features of catheter-related infections at PAHBCU. PMID:20563443

Campos Júnior, Cláudio Penido; Sanches, Patrícia; Tedokon, Elizabete Aparecida; Souza, Ana Carolina Remondi; Machado, Ricardo Luiz Dantas; Rossit, Andréa Regina Baptista

2010-01-01

368

Interim Summary: Nesting Counts of Ospreys and Brown Pelicans in Northwestern Mexico, 2006  

USGS Publications Warehouse

The distribution and abundance of nesting populations of California brown pelicans (Pelecanus occidentalis californicus) and ospreys (Pandion haliaetus) were documented in 2006 in northwestern Mexico. For ospreys only, the 2006 data were compared to population estimates from two previous surveys (one conducted in 1977 and another conducted in the period 1992-1993). Overall, the total osprey nesting population increased from 1977 to 1992-1993 and then only changed slightly by 2006, but included regions with localized declines, increases, and stable populations. Preliminary population estimates for California brown pelicans suggest a large and apparently healthy breeding population.

Henny, Charles J.; Anderson, Daniel W.

2007-01-01

369

A new threatened species of Pandanaceae from northwestern Madagascar, Pandanus sermolliana  

PubMed Central

Pandanus sermolliana Callmander & Buerki (Pandanaceae) is described from humid forests in the Galoka mountain chain in northwestern Madagascar. The new species can be easily distinguished from the other members of the genus it most closely resembles, P. insuetus Huynh and P. perrieri Martelli, by several morphological characters including drupes that are incompletely fused, with each of the dome-like carpels separated from the base of the pileus, and stigmas that are sub-vertical or rarely sub-horizontal, slightly spinescent, and raised on an incompletely united base. This distinctive species is rare and is classified as Critically Endangered based on IUCN threat criteria.

Callmander, Martin W.; Buerki, Sven; Wohlhauser, Sebastien

2011-01-01

370

Carbon isotopic composition of deep carbon gases in an ombrogenous peatland, northwestern Ontario, Canada  

SciTech Connect

Radiocarbon dating and carbon isotope analyses of deep peat and gases in a small ombrogenous peatland in northwestern Ontario reveals the presence of old gases at depth that are 1000-2000 yr younger than the enclosing peat. The authors suggest that the most likely explanation to account for this age discrepancy is the downward movement by advection of younger dissolved organic carbon for use by fermentation and methanogens bacteria. This study identifies a potentially large supply of old carbon gases in peatlands that should be considered in global carbon models of the terrestrial biosphere.

Aravena, R. (Univ. of Waterloo, Ontario (Canada). Center for Groundwater Research and Wetlands Research Center); Warner, B.G. (Univ. of Waterloo, Ontario (Canada). Wetlands Research Center and Dept. of Geography); Charman, D.J. (Univ. of Plymouth, Devon (United Kingdom). Dept. of Geographical Sciences); Belyea, L.R. (Queen Mary and Westfield College, London (United Kingdom). School of Biological Sciences); Mathur, S.P. (Foxleigh Crescent, Kanata, Ontario (Canada)); Dinel, H. (Center for Land and Biological Resources Research, Agriculture Canada, Ontario (Canada))

1993-01-01

371

Wall-rock argillic alteration and uranium mineralization of the northwestern Strel’tsovka caldera  

Microsoft Academic Search

Alteration of rocks and localization of uranium mineralization in the northwestern Strel’tsovka caldera are exemplified in\\u000a the Dal’nee deposit. In the main parameters of hydrothermal mineralization (temperature, pH, pressure, and composition of\\u000a solution), the Dal’nee deposit differs from the deposits of the Strel’tsovka ore field located in the central part of the\\u000a caldera. The localization of high-grade stratiform orebodies are

O. V. Andreeva; V. A. Golovin; V. A. Petrov

2010-01-01

372

Vertical fluxes of aromatic and aliphatic hydrocarbons in the Northwestern Mediterranean Sea  

Microsoft Academic Search

Aliphatic and aromatic hydrocarbon fluxes were measured in time series sediment trap samples at 200m and at 1000m depths in the open Northwestern Mediterranean Sea, from December 2000 to July 2002. Averaged fluxes of n-alkanes, UCM and T-PAH35 were 2.96±2.60?gm?2d?1, 64±60?gm?2d?1 and 0.68±0.59?gm?2d?1, respectively. Molecular compositions of both hydrocarbon classes showed a contamination in petrogenic hydrocarbons well above the background

Rémi Deyme; Ioanna Bouloubassi; Marie-Hélène Taphanel-Valt; Juan-Carlos Miquel; Anne Lorre; Jean-Claude Marty; Laurence Méjanelle

2011-01-01

373

Effect of melt–rock interaction on geochemistry in the Kudi ophiolite (western Kunlun Mountains, northwestern China): implication for ophiolite origin  

Microsoft Academic Search

Major, trace and rare earth elements (REE), and platinum group elements (PGE) geochemistry have been studied for the Kudi ophiolite in the northwestern part of the western Kunlun Mountains, northwestern China, in order to determine the relationship between the mantle peridotites and mafic lavas and the origin of the ophiolite. The ophiolite consists of harzburgites, dunites, cumulate dunites, pyroxenites and

Zhihong Wang; Shu Sun; Quanlin Hou; Jiliang Li

2001-01-01

374

Origin of the gypsum-rich silica nodules, Moghra Formation, Northwest Qattara depression, Western Desert, Egypt  

Microsoft Academic Search

Gypsum rich-silica nodules appear in two shale horizons of the Moghra Formation (early Miocene) northwestern Qattara Depression, Western Desert, Egypt. These nodules are gray to milky white in colour, mostly botroidal and rose-like in shape and range in diameter from 2 to 7.5 cm. The silica nodule-bearing shale is composed mainly of smectite with a little minor kaolinite.The silica nodules

Essam M. El Khoriby

2005-01-01

375

Origin of the gypsum-rich silica nodules, Moghra Formation, Northwest Qattara depression, Western Desert, Egypt  

Microsoft Academic Search

Gypsum rich-silica nodules appear in two shale horizons of the Moghra Formation (early Miocene) northwestern Qattara Depression, Western Desert, Egypt. These nodules are gray to milky white in colour, mostly botroidal and rose-like in shape and range in diameter from 2 to 7.5 cm. The silica nodule-bearing shale is composed mainly of smectite with a little minor kaolinite. The silica

Essam M. El Khoriby

2005-01-01

376

Extractable alkyldibenzothiophenes in Posidonia Shale (Toarcian) source rocks: Relationship of yields to petroleum formation and expulsion  

Microsoft Academic Search

Extractable C 0 to C 2 dibenzothiophenes were determined by capillary gas chromatography in 125 rock samples of the Posidonia Shale formation with vitrinite reflectance (R r ) between 0.4 and 1.5% mostly derived from the Hils syncline area in northwestern Germany. Average yields of individual methyldibenzothiophenes in the range of 2-110 g\\/g total organic carbon (TOC) are comparable to

M. Radke; H. Willsch

1994-01-01

377

Geohydrology of the lower Apalachicola-Chattahoochee-Flint River basin, southwestern Georgia, northwestern Florida, and southeastern Alabama  

USGS Publications Warehouse

The lower Apalachicola-Chattahoochee-Flint (ACF) River Basin contains about 4,600 square miles of karstic and fluvial plains and nearly 100,000 cubic miles of predominantly karst limestone connected hydraulically to the principal rivers and lakes in the Coastal Plain of southwestern Georgia, northwestern Florida, and southwestern Alabama. Sediments of late-middle Eocene to Holocene in hydraulic connection with lakes, streams, and land surface comprise the surficial aquifer system, upper semiconfining unit, Upper Floridan aquifer, and lower semiconfining unit and contribute to the exchange of ground water and surface water in the stream-lake-aquifer flow system. Karst processes, hydraulic properties, and stratigraphic relations limit ground-water and surface-water interaction to the following hydrologic units of the stream-lake-aquifer flow system: the surficial aquifer system, upper semiconfining unit, Upper Floridan aquifer, and lower confining unit. Geologic units corresponding to these hydrologic units are, in ascending order: Lisbon Formation; Clinchfield Sand; Ocala, Marianna, Suwannee, and Tampa Limestones; Hawthorn Group; undifferentiated overburden (residuum); and terrace and undifferentiated (surficial) deposits. Similarities in hydraulic properties and direct or indirect interaction with surface water allow grouping sediments within these geologic units into the aforementioned hydrologic units, which transcend time-stratigraphic classifications and define the geohydrologic framework for the lower ACF River Basin. The low water-transmitting properties of the lower confining unit, principally the Lisbon Formation, allow it to act as a nearly impermeable base to the stream-lake-aquifer flow system. Hydraulic connection of the surficial aquifer system with surface water and the Upper Floridan aquifer is direct where sandy deposits overlie the limestone, or indirect where fluvial deposits overlie clayey limestone residuum. The water level in perched zones within the surficial aquifer system fluctuates independently of water-level changes in the underlying aquifer, adjacent streams, or lakes. Where the surficial aquifer system is connected with surface water and the Upper Floridan aquifer, water-table fluctuations parallel those in adjacent streams or the underlying aquifer. More...

Torak, Lynn J.; Painter, Jaime A.

2006-01-01

378

Significance of the fine drainage pattern for submarine canyon evolution: The Foix Canyon System, Northwestern Mediterranean Sea  

NASA Astrophysics Data System (ADS)

Submarine gullies are relatively small valleys that occur in a variety of submarine slopes. They are very common in continental slopes and in submarine canyon heads and flanks, where they often form tributary networks. Gullies are smaller than submarine canyons, though there is no standardised size criterion to distinguish between them. Gullies and gully networks have been often viewed as initial steps in the development of larger submarine canyons and more mature drainage networks. The shelf-incising submarine Foix Canyon System (FCS) is located in the northwestern Mediterranean Sea. Numerous, well-developed and morphologically diverse gullies carve its two heads and flanks. The objective of this study is to analyse the drainage network of the FCS and decipher the role of gullies in its evolution. Submarine gully and canyon networks were extracted from swath bathymetry data of 50 m grid size using Geographic Information Systems (GIS). A systematic morphometric analysis was carried out on drainage network of the FCS by using the Horton-Strahler method. Our results show that the FCS is formed by 1660 streams, 1000 km in total length, which can be classified to six stream orders. To detect relevant morphological changes along valley sections, the drainage density, the stream frequency and the drainage area relief parameters were applied. Furthermore, a branching index (Ib) was developed to characterise the geometry of the submarine drainage network. In the canyon heads Ib values are ~ 1.7, which correspond to a dendritic network, whereas Ib in the canyon branches displays values of ~ 2.2 corresponding to a pinnate one. At a finer scale, we have identified two types of canyon flank gullies, namely "rim gullies" and "toe gullies": (1) rim gullies form large, dendritic networks that extend from the canyon thalweg up to the canyon rim, and (2) toe gullies form smaller pinnate networks restricted to the lower part of the canyon flanks. The formation and development of rim gullies are interpreted as the main process responsible for canyon head growth and across-flank transport of material from the continental shelf. Toe gullies, on the other hand, are the morphological expression of the rejuvenation of rim gullies and the canyon itself. Axial incision and toe gully formation are interpreted as the result of bottom-to-top erosive processes acting at different scales, in response to regional and local changes of the factors controlling the system, respectively. This study helps to identify a variety of gullies and the processes they result from and provides a morphometric methodology to characterise submarine drainage networks at fine resolution scales.

Tubau, Xavier; Lastras, Galderic; Canals, Miquel; Micallef, Aaron; Amblas, David

2013-02-01

379

Seroprevalence of Leishmania infantum in northwestern Spain, an area traditionally considered free of leishmaniasis.  

PubMed

Northwestern Spain has traditionally been considered to be free from leishmaniasis. The aim of this work was to determine the prevalence of canine leishmaniasis in this area and to assess the influence of several risk factors on the incidence of this disease. A total of 479 dogs attended at different veterinary clinics in northwestern Spain were tested for L. infantum with the immunofluorescent antibody (IFA) test. The seroprevalence of L. infantum in this area was 3.7%. Most of the seropositive dogs lived in two locations: Valdcorras (seroprevalence of 29.2%) and Ourense (seroprevalence of 7.5%). The detection of high antibody titers in most of the seropositive dogs (many of which presented clinical signs) coupled with the certainity that some of these dogs had never been outside their home areas indicates the presence of this zoonosis in these two sites. On the other hand, companion dogs were significantly less likely to acquire the disease than sheep dogs, hunting dogs, and those from kennels. PMID:15604485

Amusategui, Inmaculada; Sainz, Angel; Aguirre, Enara; Tesouro, Miguel A

2004-10-01

380

Mineral precipitation and dissolution at two slag-disposal sites in northwestern Indiana, USA  

USGS Publications Warehouse

Slag is a ubiquitous byproduct of the iron- and steel-refining industries. In northwestern Indiana and northeastern Illinois, slag has been deposited over more than 52 km2 of land surface. Despite the widespread use of slag for fill and construction purposes, little is known about its chemical effects on the environment. Two slagdisposal sites were examined in northwestern Indiana where slag was deposited over the native glacial deposits. At a third site, where slag was not present, background conditions were defined. Samples were collected from cores and drill cuttings and described with scanning electron microscopy and electron microprobe analysis. Ground-water samples were collected and used to assess thermodynamic equilibria between authigenic minerals and existing conditions. Differences in the mineralogy at background and slag-affected sites were apparent. Calcite, dolomite, gypsum, iron oxides, and clay minerals were abundant in native sediments immediately beneath the slag. Mineral features indicated that these minerals precipitated rapidly from slag drainage and co-precipitated minor amounts of non-calcium metals and trace elements. Quartz fragments immediately beneath the slag showed extensive pitting that was not apparent in sediments from the background site, indicating chemical weathering by the hyperalkaline slag drainage. The environmental impacts of slag-related mineral precipitation include disruption of natural ground-water flow patterns and bed-sediment armoring in adjacent surface-water systems. Dissolution of native quartz by the hyperalkaline drainage may cause instability in structures situated over slag fill or in roadways comprised of slag aggregates.

Bayless, E. R.; Schulz, M. S.

2003-01-01

381

Association of PDE4B polymorphisms and schizophrenia in Northwestern Han Chinese.  

PubMed

The phosphodiesterase 4B (PDE4B) is a candidate susceptibility gene for schizophrenia (SCZ), interacting with DISC1, a known genetic risk factor for SCZ. To examine if variants within PDE4B gene are associated with SCZ in Northwestern Han Chinese, and if these effects vary in gender-specific subgroup, we analyzed 20 SNPs, selected from previous studies and preliminary HapMap data analyses with minor allele frequency (MAF) ? 20%, in a cohort of 428 cases and 572 controls from genetically independent Northwestern Han Chinese. Single SNP association, haplotype association and sex-specific association analysis were performed. We found that rs472952 is significantly associated with SCZ and rs7537440 is associated with SCZ in females. Further analysis indicated that a haplotype block spanning PDE4B2 splice site is highly associated with SCZ and several haplotypes in this block have about twofold to threefold increase in cases. Our results provide further evidence that PDE4B may play important roles in the etiology of SCZ. PMID:22160351

Guan, Fanglin; Zhang, Chen; Wei, Shuguang; Zhang, Hongbo; Gong, Xiaomin; Feng, Jiali; Gao, Chengge; Su, Rong; Yang, Huanming; Li, Shengbin

2012-07-01

382

Forest site-quality estimation using Forest Ecosystem Classification in Northwestern Ontario.  

PubMed

Site index for jack pine, black spruce and trembling aspen was found to be poorly related to soil types described in the Northwestern Ontario Forest Ecosystem Classification (NWO FEC). Statistical analyses showed that average site indices for most soil types and groupings of soil types were not significantly different from each other.Site index varies greatly within presently defined NWO FEC soil types because certain soil and topographic features that are closely related to site index vary greatly within soil types or are not well described by the NWO FEC soil types. These critical soil features have been identified by soil-site studies that show features most closely related to site index usually are surface soil features found within the effective rooting zone of forest trees. These critical features include depth to bedrock, depth to root restricting soil layers, and coarse fragment content and texture of surface soil horizons.Site-quality research in Northwestern Ontario is closely integrated with the NWO FEC program, thus future NWO FEC soil classifications probably will use results from our soil-site research as a basis for soil type revisions. The result will be future soil types that are more closely related to forest site quality and thus to the capability of forest land to produce tree growth. PMID:24198025

Carmean, W H

1996-01-01

383

Aerosols properties during dust-storm episodes over Jaipur, Northwestern India  

NASA Astrophysics Data System (ADS)

Continuous routine aerosol measurements have been carried out at Jaipur (Rajasthan, Northwestern India) since April 2009 with a CIMEL sun photometer integrated in the global Aerosols Robotic Network (AERONET) program. The present study investigates the aerosol properties during dust storm episodes over Jaipur, Northwestern India. A series of high dust storms were identified as indicated by high values of aerosols optical thickness (AOT) with a significant drop in angstrom exponent values (nearly zero and negative). Consequently, a progressive increase in Single Scattering Albedo (SSA440 nm = 0.89, SSA675 nm = 0.95, SSA870 nm = 0.97, SSA1020 nm = 0.976) suggests more scattering nature of regional aerosols associated with abundant dust loading. Trajectories back in time showed that the air collected in Jaipur during dust period originated from desert regions in the western part of India. Additionally, a comparative analysis of the mean AOT derived from satellite data and Potential Source Contribution Function (PSCF) analysis helped to understand the source region of these particles.

Payra, Swagata; Verma, Sunita; Prakash, Divya; Kumar, Pramod; Soni, Manish; Holben, Brent

2013-05-01

384

Highly nonlinear internal solitary waves over the continental shelf of the northwestern South China Sea  

NASA Astrophysics Data System (ADS)

Large amplitude internal solitary waves (ISWs) often exhibit highly nonlinear effects and may contribute significantly to mixing and energy transporting in the ocean. We observed highly nonlinear ISWs over the continental shelf of the northwestern South China Sea (19°35'N, 112°E) in May 2005 during the Wenchang Internal Wave Experiment using in-situ time series data from an array of temperature and salinity sensors, and an acoustic Doppler current profiler (ADCP). We summarized the characteristics of the ISWs and compared them with those of existing internal wave theories. Particular attention has been paid to characterizing solitons in terms of the relationship between shape and amplitude-width. Comparison between theoretical prediction and observation results shows that the high nonlinearity of these waves is better represented by the second-order extended Korteweg-de Vries (KdV) theory than the first-order KdV model. These results indicate that the northwestern South China Sea (SCS) is rich in highly nonlinear ISWs that are an indispensable part of the energy budget of the internal waves in the northern South China Sea.

Xu, Zhenhua; Yin, Baoshu; Hou, Yijun

2010-09-01

385

Seroprevalence of Toxoplasma gondii infection in dairy goats in Shaanxi Province, Northwestern China  

PubMed Central

Background Toxoplasma gondii is an important zoonotic pathogen causing significant human and animal health problems. Infection in dairy goats not only results in significant reproductive losses, but also represents an important source of human infection due to consumption of infected meat and milk. In the present study we report for the first time seroprevalence of T. gondii infection in Guanzhong and Saanen dairy goats in Shaanxi province, Northwestern China. Results Sera from 751 dairy goats from 9 farms in 6 counties were examined for T. gondii antibodies with an indirect haemagglutination (IHA) test. Antibodies to T. gondii were detected in 106 (14.1%) serum samples, with antibody titres ranging from 1:64 to 1:1024. Seropositive goats were found in all 9 farms and seroprevalences in Guanzhong (16.3%, 75/461) and Saanen (10.7%, 31/290) dairy goats were not statistically significantly different. All the factors (sex, age and location) reported in the present study affected prevalence of infection, and seroprevalence increased with age, suggesting postnatal acquisition of T. gondii infection. Conclusions The results of the present survey indicate that infection by T. gondii is widely prevalent in dairy goats in Shaanxi province, Northwestern China, and this has implications for prevention and control of toxoplasmosis in this province.

2011-01-01

386

Genetic structuring of remnant forest patches in an endangered medicinal tree in North-western Ethiopia  

PubMed Central

Background Habitat loss and fragmentation may have detrimental impacts on genetic diversity, population structure and overall viability of tropical trees. The response of tropical trees to fragmentation processes may, however, be species, cohort or region-specific. Here we test the hypothesis that forest fragmentation is associated with lower genetic variability and higher genetic differentiation in adult and seedling populations of Prunus africana in North-western Ethiopia. This is a floristically impoverished region where all but a few remnant forest patches have been destroyed, mostly by anthropogenic means. Results Genetic diversity (based on allelic richness) was significantly greater in large and less-isolated forest patches as well as in adults than seedlings. Nearly all pairwise FST comparisons showed evidence for significant population genetic differentiation. Mean FST values were significantly greater in seedlings than adults, even after correction for within population diversity, but varied little with patch size or isolation. Conclusions Analysis of long-lived adult trees suggests the formerly contiguous forest in North-western Ethiopia probably exhibited strong spatial patterns of genetic structure. This means that protecting a range of patches including small and isolated ones is needed to conserve the extant genetic resources of the valuable forests in this region. However, given the high livelihood dependence of the local community and the high impact of foreign investors on forest resources of this region, in situ conservation efforts alone may not be helpful. Therefore, these efforts should be supported with ex situ gene conservation actions.

2014-01-01

387

Simulating the impacts of groundwater pumping on stream aquifer dynamics in semiarid northwestern Oklahoma, USA  

NASA Astrophysics Data System (ADS)

Visual MODFLOW, a numerical groundwater flow model, was used to evaluate the impacts of groundwater exploitation on streamflow depletion in the Alluvium and Terrace aquifer of the Beaver-North Canadian River (BNCR) in northwestern Oklahoma, USA. Water demand in semi-arid northwestern Oklahoma is projected to increase by 53% during the next five decades, driven primarily by irrigation, public water supply, and agricultural demand. Using MODFLOW’s streamflow routing package, pumping-induced changes in baseflow and stream leakage were analyzed to estimate streamflow depletion in the BNCR system. Simulation results indicate groundwater pumping has reduced baseflow to streams by approximately 29% and has also increased stream leakage into the aquifer by 18% for a net streamflow loss of 47%. The magnitude and intensity of streamflow depletion, however, varies for different stream segments, ranging from 0 to 20,804 m3/d. The method provides a framework for isolating and quantifying impacts of aquifer pumping on stream function in semiarid alluvial environments.

Zume, Joseph; Tarhule, Aondover

2008-06-01

388

Distribution of clinically important thermophilic actinomycetes in vegetable substrates and soil in north-western India.  

PubMed

Medically important thermophilic actinomycetes were isolated from 218 (64%) of 341 samples of vegetable substrates and soil examined from sites in north-western India. Thermoactinomyces vulgaris (T. candidus) was the commonest species, occurring in 56% of samples, followed by Saccharomonospora viridis in 29%, Thermoactinomyces thalpophilus in 27%, Faenia rectivirgula (Micropolyspora faeni) in 21% and Thermoactinomyces sacchari in 14%. T. vulgaris and T. thalpophilus were isolated from all types of substrate examined, with T. vulgaris always more common than T. thalpophilus. Of the other thermophilic actinomycetes, F. rectivirgula was isolated predominantly from hay (44%) and S. viridis (56%) and T. sacchari (44%) from sugar-cane bagasse. The largest populations of T. vulgaris and T. thalpophilus were found in paddy straw, followed by T. sacchari, S. viridis and F. rectivirgula in sugar-cane bagasse. The widespread occurrence of these clinically important thermophilic actinomycetes suggests that exposure of humans and animals to them may be frequent in north-western India. Studies are required to determine the prevalence of extrinsic allergic alveolitis (hypersensitivity pneumonitis) caused by thermophilic actinomycetes in the local population. PMID:2589849

Gangwar, M; Khan, Z U; Randhawa, H S; Lacey, J

1989-10-01

389

Lateral variations in the upper mantle velocity structure in the northwestern pacific margin  

NASA Astrophysics Data System (ADS)

The upper mantle velocity structure in various island arc-marginal sea regions of the northwestern Pacific has been studied in detail to a depth of about 640 km from the analysis of P- and S-wave travel times data of 363 earthquakes with focal depths varying from 35 to 640 km. Wave velocities were obtained at the depths of foci by using Kaila's (1969) analytical method in several units of the northwestern Pacific margin: (1) Honshu-Izu Bonin-Japan Sea, (2) Kyushu-Shikoku, (3) Hokkaido, (4) Okhotsk Sea, (5) southern Kurile Islands, (6) northern Kurile Islands, (7) Kamchatka, (8) Ryukyu Islands, and (9) Taiwan-Luzon. There is substantial evidence for large lateral variations, of the order of 8-10%, in both P- and S-wave velocity structure to about 250 km depth within the subducting lithospheric slab in the northwestern Pacific margin. The P velocity determined at 40 km depth, is found to be about 8.20 km/sec in the southern Kurile Islands 7.90 km/sec in the northern Kurile Islands, and the Japanese Is., 7.80 km/sec in Kamchatka and 8.05 km/sec in the Ryukyu Islands, and Taiwan-Luzon regions. The S velocity determined at 40 km depth, in the southern Kurile Is., is also found to be relatively higher, about 4.60 km/sec, compared to all other regions in the northwestern Pacific margin where it is varying from 4.30 to 4.45 km/sec. P and S velocities determined to about 185 km depth in the southern Kurile Islands region are found to be 3-5% higher than those obtained at comparable depths in the Hokkaido island, northern Kurile Islands and Kamchatka. P. velocities, determined to a depth of about 255 km, in the Ryukyu and Taiwan-Luzon regions are quite similar and are about 5% higher on the average, than the nearly constant P velocity of 7.88 km/sec found in the Kyushu and Shikoku islands of the southwest Japan. In the southwest Japan region, both P and S wave velocities are found to remain constant to almost 255 km depth. This might be due to the presence of a large magma chamber resulting also in the extensive volcanic activity observed in southwest Japan (e.g. Sakurazima volcano). The P- and S-wave velocity-depth functions, determined in the depth range of 290-640 km, in the Okhotsk Sea region, reveal a sharp first-order velocity discontinuity at 390 km depth. The observed velocity jumps are 9.2% for P and 5.6% for S waves in this region. In the central Japan region also, comprising the Honshu and the Japan Sea, there is a sharp first-order velocity discontinuity at depths of 365 km for P and 345 km for S waves with associated velocity jumps of 8.6% for P and 4.8% for S waves. The S velocities below this discontinuity to about 640 km depth in the central Japan and the Okhotsk sea regions are found to be considerably lower. The entire area, comprising the high heat-flow regions of the marginal seas of Japan and Okhotsk, may be a high temperature/high attenuation zone extending to 640 km depth. There is no evidence for the presence of a significant low-velocity layer in the northwestern Pacific margin.

Kaila, K. L.; Krishna, V. G.

1985-03-01

390

Metsovo lung: Pleural calcification and restrictive lung function in northwestern Greece. Environmental exposure to mineral fiber as etiology  

Microsoft Academic Search

Pleural calcifications are described in 122 of 268 (45.5%) inhabitants of four villages (Metsovo, Anilio, Milea, and Votonosi) in a small area of northwestern Greece (total population about 5000). All affected individuals are of one ethnic group, Vlachi. Calcifications were not noted in any of the 103 persons in the control group made up of 73 non-Vlachi inhabitants from the

S. H. Constantopoulos; J. A. Goudevenos; N. Saratzis; A. M. Langer; I. J. Selikoff; H. M. Moutsopoulos

1985-01-01

391

Single-dose methotrexate for the treatment of ectopic pregnancy: Northwestern Memorial Hospital three-year experience  

Microsoft Academic Search

OBJECTIVE: Our purpose was to evaluate the effectiveness of single-dose intramuscular methotrexate in the treatment of ectopic pregnancies by physicians in the Department of Obstetrics and Gynecology of Northwestern Memorial Hospital and to compare the results with those of previously published studies. STUDY DESIGN: A retrospective chart review was performed of 50 patients with ectopic pregnancies treated with single-dose methotrexate

Catherine S. Stika; Lanetta Anderson; Marilynn C. Frederiksen

1996-01-01

392

Report on the Results of a Survey of Northwestern High School Students. High School Improvement Project, June 1982.  

ERIC Educational Resources Information Center

In May 1982, students at Northwestern High School in Detroit, Michigan, were asked to assess the instructional program, student activities, counseling services, morale, and administration at the school. Conducted as part of the High School Improvement Project involving eight Detroit high schools, the survey was designed to collect information…

Stavros, Denny

393

Report on the Results of a Survey of Northwestern High School Staff. High School Improvement Project, June 1982.  

ERIC Educational Resources Information Center

As part of the evaluation of the High School Improvement Project (HSIP), a survey was conducted to measure staff perceptions of school and instructional effectiveness behaviors and activities at Northwestern High School in Detroit, Michigan. The questionnaire used was an abbreviated version of the School Effectiveness Questionnaire developed by…

Stavros, Denny

394

Land suitability assessment for perennial crops using remote sensing and Geographic Information Systems: A case study in northwestern Egypt  

Microsoft Academic Search

The main objective of this study was to develop a Geographic Information Systems-based model for land suitability assessment for guava, olive and date palm in the North-western coast of Egypt. Soil, climatic and landscape database as well as satellite image have been integrated through Geographic Information Systems (GIS). A Landsat ETM+ image dated 2001, was classified using maximum likelihood classifier

A. Shalaby; Y. O. Ouma; R. Tateishi

2006-01-01

395

Geothermal resources of the western arm of the Black Rock Desert, northwestern Nevada. Part I. Geology and geophysics  

Microsoft Academic Search

Studies of the geothermal potential of the western arm of the Black Rock Desert in northwestern Nevada included a compilation of existing geologic data on a detailed map, a temperature survey at 1-meter depth, a thermal-scanner survey, and gravity and seismic surveys to determine basin geometry. The temperature survey showed the effects of heating at shallow depths due to rising

D. H. Schaefer; A. H. Welch; D. K. Maurer

1983-01-01

396

Geology, geochemistry, and origin of volcanic rock-hosted uranium deposits in northwestern Nevada and southeastern Oregon, USA  

Microsoft Academic Search

Northwestern Nevada and southeastern Oregon have the largest uranium (U) deposits in Tertiary volcanic rocks in the US. Most deposits are in or adjacent to calderas or rhyolite lava-dome fields and are hydrothermal. Almost all are associated with rhyolites that have high primary U concentrations (9 to 20 ppm), but the rhyolites range from peralkaline to peraluminous. Caldera-related occurrences are

Stephen B. Castor; Christopher D. Henry

2000-01-01

397

Episodic dike intrusions in the northwestern Sierra Nevada, California: Implications for multistage evolution of a Jurassic arc terrane  

Microsoft Academic Search

In the northwestern Sierra Nevada, California, volcanic and plutonic rocks of the Smartville and Slate Creek complexes, both fragments of a Jurassic arc terrane, are tectonically juxtaposed against ophiolitic and marine rocks that represent late Paleozoic-early Mesozoic oceanic basement. This oceanic basement is intruded by Early Jurassic dikes that are coeval with hypabyssal and plutonic rocks within the Smartville and

Yildirim Dilek; Peter Thy; Eldridge M. Moores

1991-01-01

398

Responses of snowmelt runoff to climatic change in an inland river basin, Northwestern China, over the past 50a  

Microsoft Academic Search

The spatial and temporal variations of snowcover distribution, and snowmelt runoffs are considered as sensitive indicators for climatic change. The purpose of this paper is to analyze and forecast the responses of snowmelt runoff to climate change. The upstream of Heihe River Basin in Northwestern China was chose as the representative catchments, and the observation data of the meteorological and

J. Wang; H.-Y. Li; X.-H. Hao

2010-01-01

399

Dense mineral data from the northwestern Himalayan foreland sedimentary rocks and recent river sediments: evaluation of the hinterland  

Microsoft Academic Search

The World's largest peripheral foreland basin, developed in front of the rising Himalaya, incorporates a sedimentary pile on the order of 104m in thickness. Temporal variation in the heavy mineral record exists in the northwestern Himalayan Foreland succession due to a change in the composition of the hinterland. This study was conducted in order to correlate the heavy minerals occurring

B. P Singh; J. S Pawar; S. K Karlupia

2004-01-01

400

Unstructured, anisotropic mesh generation for the Northwestern European continental shelf, the continental slope and the neighbouring ocean  

Microsoft Academic Search

A new mesh refinement strategy for generating high quality unstructured meshes of the Northwestern European continental shelf, the continental slope and the neighbouring ocean is presented. Our objective is to demonstrate the ability of anisotropic unstructured meshes to adequately address the challenge of simulating the hydrodynamics occurring in these three regions within a unique mesh. The refinement criteria blend several

Sébastien Legrand; Eric Deleersnijder; Eric Delhez; Vincent Legat

2007-01-01

401

Petroleum migration and mixing in the northwestern Junggar Basin (NW China): constraints from oil-bearing fluid inclusion analyses  

Microsoft Academic Search

Abundant oil-bearing fluid inclusions are present in four reservoir sandstone samples from the slope and fault zone areas in the northwestern margin of the Junggar Basin (NW China). Free oil in intergranular pores, adsorbed oil on grain surfaces, and petroleum in inclusions hosted by mineral grains of these samples were analyzed by gas chromatography and gas chromatography–mass spectrometry. Analytical results

Jian Cao; Suping Yao; Zhijun Jin; Wenxuan Hu; Yijie Zhang; Xulong Wang; Yueqian Zhang; Yong Tang

2006-01-01

402

Description of Vegetation of the Oak Openings of Northwestern Ohio at the Time of Euro-American Settlement 1  

Microsoft Academic Search

Original land survey notes were used to produce a map of the Oak Openings of northwestern Ohio showing the vegetation at the time of Euro-American settlement (1817-1832). For that period, the area of the Oak Openings was 43% Oak Savanna, 27% Wet Prairie, 23% Oak Woodland, 7% Oak Barrens, and <1% Floodplain Forest. The composition of the tree layer was

LAWRENCE G. BREWER; JOHN L. VANKAT

403

Culture, Climate and the Environment: Local Knowledge and Perception of Climate Change among Apple Growers in Northwestern India  

Microsoft Academic Search

Human societies in mountainous areas have evolved specific ways of dealing with the constraints imposed by the environment. A number of anthropological studies have documented the existence of practices that can be considered adaptive in the context of mountain environments. In this paper, I present a case study of a society in transition, in the northwestern Himalayas of India, in

Neeraj Vedwan

404

75 FR 62519 - Northern Illinois Gas Company; Lee 8 Storage Partnership; NorthWestern Corporation; The East Ohio...  

Federal Register 2010, 2011, 2012, 2013

...PR10-126-000;. PR10-127-000; PR10-128-000; PR10-129-000 (Not Consolidated)] Northern Illinois Gas Company; Lee 8 Storage Partnership; NorthWestern Corporation; The East Ohio Gas Company; UGI Central Penn Gas, Inc.; Arkansas...

2010-10-12

405

Fractionation analysis of some heavy metals in sediments of the north-western part of the Red Sea, Egypt  

Microsoft Academic Search

Sequential extraction was used to study operationally determined chemical forms (exchangeable, carbonate, reducible metal, oxidisable metal and the residual fractions) of the metals Cd, Cu, Zn and Pb in sediments from 12 sample sites collected from the north-western part of the Red Sea, where improper recreational facilities have resulted in diverse impacts on the coastal environments fronting some of the

Hoda H. H. Ahdy; Doaa H. Youssef

2011-01-01

406

Responses of deep-water shrimp populations to intermediate nepheloid layer detachments on the Northwestern Mediterranean continental margin  

Microsoft Academic Search

A clear link between the distribution of intermediate nepheloid layer detachments on the Northwestern Mediterranean continental margin and the population structure of five congeneric megafaunal species of deep-water benthic shrimps inhabiting different depth ranges between 100 and 1100m was found. The results of the multidisciplinary approach presented in this study provide evidence for the ecological conditions that affect the spatial

Pere Puig; Francesc Sardà; Albert Palanques

2001-01-01

407

Toxicity and heavy metal contamination of surficial sediments from the Bay of Thessaloniki (Northwestern Aegean Sea) Greece  

Microsoft Academic Search

Surficial sediments (the fraction<2000 ?m) from the Bay of Thessaloniki, in the Northwestern Aegean Sea, Greece were examined for heavy metal and organic carbon contents, as well as for acute LUMIStox® toxicity of pore waters (PWs), wet sediment elutriates (WSEs) and dry sediment elutriates (DSEs) obtained from the solid material remaining after PW extraction. WSEs where not toxic. EC20\\/50 values

Konstantinos Zabetoglou; Demetra Voutsa; Constantini Samara

2002-01-01

408

Towards an integration of conventional land evaluation methods and farmers’ soil suitability assessment: a case study in northwestern Syria  

Microsoft Academic Search

Adaptation of land use to the potentialities and constraints of local agroecologies is a key principle of sustainable land management. Farmers and land resource professionals assess the options that optimise the productivity and sustainable land use through different knowledge systems. Both systems have advantages and drawbacks. Through a case study in a village of northwestern Syria, an approach was developed

N Cools; E De Pauw; J Deckers

2003-01-01

409

[Digenea of Haliaeetus albicilla (Linnaeus, 1758) and Pandion haliaetus (Linnaeus, 1758) from middle and north-western Poland].  

PubMed

In 2003-2008 eight white-tailed eagles and two ospreys from middle and north-western Poland were examined for the presence of parasites. Nine birds were infected with 5 digenean species: Conodiplostomum perlatum, Paracoenogonimus ovatus, Strigeafalconis, Metorchis crassiusculus and Nematostrigea serpens. M. crassiusculus was found for the first time in an eagle from Poland. PMID:19338229

Kalisi?ska, Elzbieta; Rzad, Izabella; Sitko, Jilji; Kavetska, Katarzyna M; Królaczyk, Katarzyna; Budis, Halina

2008-01-01

410

Changes in vegetation after 22 years' natural restoration in the Karst disturbed area in northwestern Guangxi, China  

Microsoft Academic Search

Variations of plant vegetation and spatial distribution were investigated in the areas of 4 types of typical disturbance, which had been under natural restoration for 22 years in the Karst area in northwestern Guangxi while the climax plant community was utilized as control. The slope scale and disturbance theory were used to study the plant diversity in the whole area

Fuping Zeng; Wanxia Peng; Tongqing Song; Kelin Wang; Haiyong Wu; Xijuan Song; Zhaoxia Zeng

2007-01-01

411

Depositional systems, diagenesis, and hydrocarbon entrapment in Upper Atokan Caddo clastic interval of northwestern Fort Worth Basin  

Microsoft Academic Search

The upper Atokan Caddo conglomerate and sandstone interval was deposited by a wave-reworked braid delta system. This system prograded southeastwardly from the uplifted Electra arch into the adjacent northwestern extremity of the still-actively subsiding Fort Worth basin. Subsurface net sandstone isolith, sandstone percentage, clastic ratio, and interval isopach maps prepared for the interval between the top of the Pregnant shale

A. Ammentorp

1990-01-01

412

Detection of Conduit-Controlled Ground-Water Flow in Northwestern Puerto Rico Using Aerial Photograph Interpretation and Geophysical Methods.  

National Technical Information Service (NTIS)

The development potential of ground-water resources in the karst limestone of northwestern Puerto Rico, in an area extending from Rio Camuy to Aguidilla, is uncertain as a result of limited knowledge of the location of areas where a high density of caviti...

J. Rodriguez-Martinez R. T. Richards

2001-01-01

413

Embar Formation no longer hampers milling  

SciTech Connect

The Lower Embar is a hard, abrasive, extremely tight dolomite containing 20 percent chert and some pyrite. It overlies the oil-rich Tensleep formation in the Oregon Basin Field in northwestern Wyoming. Drilling vertical wells through the Lower Embar is not a problem because the rock is brittle and easily crushed with a conventional roller bit. However, trying to shear it with a mill is a different story. This paper describes the difficulty that Marathon Oil had in trying to put a horizontal well into this field to drain the remaining oil. It describes the penetration and wear of the various mill designs used and the final procedures used to set the kick-off from the existing vertical wells.

Perdue, J.M.

1996-06-01

414

SHRIMP U-Pb zircon geochronological constraints on Cryogenian-Ediacaran tectonomagmatic events in the northwestern Arabian Shield  

NASA Astrophysics Data System (ADS)

The northwestern Arabian Shield is dominated by juvenile Neoproterozoic crust of the Midyan terrane (MT), composed of volcanosedimentary and multiple phases of intrusive rocks. Terrane protoliths are ~780-550 Ma, and reflect geotectonic changes within a regional framework of the East African Orogeny reflecting progression from a juvenile oceanic island arc and suprasubduction ophiolite to arc-arc collision to continental magmatic arc to crustal thickening with thrusting and strike-slip shearing (Najd fault system) to extensional collapse, within-plate magmatism and final cratonization. The oldest intrusive rocks (the Muwaylih suite) yield middle Cryogenian SHRIMP U-Pb zircon ages: 748±9 Ma for Imdan complex gabbro, and 736.6±9.6 Ma and 738.8±4.2 Ma for Nabt complex diorite and tonalite. They represent pretectonic intrusions in a ~750-720 Ma oceanic island arc made up of Zaam group volcanosedimentary rocks, diamictite, and banded iron formation. Bayda group subaerial felsic metavolcanic rocks (Hijr formation: ~710±12 Ma) are believed to stratigraphically overlie the Zaam group and are interpreted as volcanic equivalents of a younger phase of Muwaylih suite magmatism (~720-710 Ma). Arc-arc collision at ~710-700 Ma between the MT and the Jiddah terrane (JT) to the south resulted in the Yanbu suture and formation of an Andean-type, continental magmatic arc. This phase of continental magmatism is represented by syntectonic, calc-alkaline intrusions such as granodiorite of the Buwaydah complex (686.5±3.7 Ma), a rhyolite dike that intrudes the granodiorite (687.4±2.2 Ma), and late gabbro/diorite of the Imdan complex (676±6 Ma), all of which are assigned to the Hamadat suite (700-680 Ma). Exhumation and erosion of the magmatic arc resulted in formation of post-amalgamation (as related to the already sutured MT and JT), syntectonic basins. One of the oldest basins in the MT, filled with the few-km thick Thalbah group, appears to be intruded by granitic bodies comparable with monzogranite of the Liban complex dated at 634.5±4.6 Ma. Similar, Cryogenian/Ediacaran ages are obtained from syenogranite of the Kara Dakha complex (631.8±4.0 Ma) and Abu Suar complex (626±4 Ma). All three granitoids belong to an early stage of the Marabit suite, and represent peak activity of calc-alkaline, syntectonic arc-related magmatism. A mafic dike dated ~617.7±4.4 Ma intrudes basal sedimentary rocks in the Thalbah basin, constraining the basin minimum deposition age. Ediacaran ages of 609±3.6 Ma from syenogranite of the Ash Shab complex and 608.9±2.8 Ma from monzogranite of the Habd complex, belong to a late stage of the Marabit suite (610-600 Ma), and represent late-tectonic, calc-alkaline magmatism resulting from extensive crustal melting in an extensional regime.

Kozdrój, Wies?aw; Kennedy, Allen; Johnson, Peter R.; Zió?kowska-Kozdrój, Ma?gorzata; Kadi, Khalid

2014-05-01

415

An association between urinary cadmium and urinary stone disease in persons living in cadmium-contaminated villages in northwestern Thailand: A population study  

SciTech Connect

Excessive urinary calcium excretion is the major risk of urinary stone formation. Very few population studies have been performed to determine the relationship between environmental cadmium exposure and urinary stone disease. This population-based study examined an association between urinary cadmium excretion, a good biomarker of long-term cadmium exposure, and prevalence of urinary stones in persons aged 15 years and older, who lived in the 12 cadmium-contaminated villages in the Mae Sot District, Tak Province, northwestern Thailand. A total of 6748 persons were interviewed and screened for urinary cadmium and urinary stone disease in 2009. To test a correlation between urinary excretion of cadmium and calcium, we measured urinary calcium content in 1492 persons, who lived in 3 villages randomly selected from the 12 contaminated villages. The rate of urinary stones significantly increased from 4.3% among persons in the lowest quartile of urinary cadmium to 11.3% in the highest quartile. An increase in stone prevalence with increasing urinary cadmium levels was similarly observed in both genders. Multiple logistic regression analysis revealed a positive association between urinary cadmium levels and stone prevalence, after adjusting for other co-variables. The urinary calcium excretion significantly increased with increasing urinary cadmium levels in both genders, after adjusting for other co-variables. Elevated calciuria induced by cadmium might increase the risk of urinary stone formation in this environmentally exposed population. - Research highlights: {yields} Excessive calciuria is the major risk of urinary stone formation. {yields} We examine cadmium-exposed persons for urinary cadmium, calcium, and stones. {yields} The rate of urinary stones increases with increasing urinary cadmium. {yields} Urinary calcium excretion increases with increasing urinary cadmium. {yields} Elevated calciuria induced by cadmium may increase the risk of urinary stones.

Swaddiwudhipong, Witaya, E-mail: swaddi@hotmail.com [Department of Community and Social Medicine, Mae Sot General Hospital, Tak 63110 (Thailand)] [Department of Community and Social Medicine, Mae Sot General Hospital, Tak 63110 (Thailand); Mahasakpan, Pranee [Department of Community and Social Medicine, Mae Sot General Hospital, Tak 63110 (Thailand)] [Department of Community and Social Medicine, Mae Sot General Hospital, Tak 63110 (Thailand); Limpatanachote, Pisit; Krintratun, Somyot [Department of Internal Medicine, Mae Sot General Hospital, Tak 63110 (Thailand)] [Department of Internal Medicine, Mae Sot General Hospital, Tak 63110 (Thailand)

2011-05-15

416

On the wet and dry deposition of ionic species in the vicinity of coal-fired power plants, northwestern Greece  

NASA Astrophysics Data System (ADS)

Rainwater and deposited particle samples were collected for 1 year (October 2000-October 2001), at two sites in the area of "Eordaia Basin", northwestern Greece, where four lignite-burning power units (total capacity 4000 MW) are operated. The samples were collected on a monthly basis and analyzed for Cl -, NO 3-, SO 42-, Na +, K +, NH 4+, Ca 2+ and Mg 2+. pH and conductivity measurements were conducted only for rain samples. The lowest rain pH values measured at the two sites (S1 and S2) were 4.15 and 5.20 respectively. 40-50% of rain samples at both sites showed pH values in the acidic area (mean values: 5.13 and 5.99 respectively). The quantification of the neutralization effect of the alkaline ions showed the prevalence role of Ca, followed by NH 4, Na and Mg. Wet and dry ionic concentrations and deposition fluxes showed considerable variability between the sites with higher values for Ca and SO 4 for both sites. This could be partly attributed to the strong influence of the local emissions. Fly ash, produced in huge amounts, is the major source for Ca and SO 4 in the area even at the site of Vegoritida (S2), which is a pure remote site located out of the main wind flow of the basin. The relative contribution of wet and dry to the total annual deposition for the site of Petrana (S1) is 45% and 55% respectively for SO 4, 41% and 59% for NO 3 and 41% and 59% for Ca. Contrary, for Vegoritida site (S2) the wet deposition is the main contributor to the total, by 60-80%, for the majority of the species. The difference between the two site environments could be explained by the different local source effect, which is more obvious to dry deposition of the nearest to power plants site of Petrana. Additionally, the application of principal component analysis confirmed the different formation patterns for rain and dust and considerable difference in source emission impact between the sites.

Tsitouridou, R.; Anatolaki, Ch.

2007-01-01

417

[Spatial structure of natural foci of hantavirus on the territory of Northwestern Caucasus].  

PubMed

For the period from 2001 to 2011 zoological and epizootological studies in more than 100 points of Northwestern Caucasus including territories of Krasnodar Region and Republic of Adygea were carried out. 8723 specimens of small mammals represented by 20 rodent species and 7 insectivorous species were captured and examined. Organs and blood from 5057 specimens of creatures were studied for hantavirus infection. The presence of natural foci of circulation of 2 species of hantavirus--Dobrava/Belgrade and Tula--was established. Sochi viruses and presumably Kurkin with main natural hosts--Caucasian wood and field mice belong to the first species. Tula and Adler viruses with the main host--Microtus genus vole belong to the second species. Quantitative characteristics of infection of small mammals of various species during different seasons and years on the examined territories were obtained, that allowed to create a map of allocation of foci of hantavirus circulation that differ by structure. PMID:24605654

Okulova, N M; Khliap, L A; Varshavski?, A A; Dzagurova, T K; Iunicheva, Iu V; Riabova, T E; Baskevich, M I; Vasilenko, L E; Tkachenko, E A

2013-01-01

418

Assimilation of HF radar surface currents to optimize forcing in the northwestern Mediterranean Sea  

NASA Astrophysics Data System (ADS)

HF radar measurements are used to optimize surface wind forcing and baroclinic open boundary condition forcing in order to constrain model coastal surface currents. This method is applied to a northwestern Mediterranean (NWM) regional primitive equation model configuration. A new radar data set, provided by two radars deployed in the Toulon area (France), is used. To our knowledge, this is the first time that radar measurements of the NWM Sea are assimilated into a circulation model. Special attention has been paid to the improvement of the model coastal current in terms of speed and position. The data assimilation method uses an ensemble Kalman smoother to optimize forcing in order to improve the model trajectory. Twin experiments are initially performed to evaluate the method skills. Real measurements are then fed into the circulation model and significant improvements to the modeled surface currents, when compared to observations, are obtained.

Marmain, J.; Molcard, A.; Forget, P.; Barth, A.; Ourmières, Y.

2014-06-01

419

Tectonic, volcanic, and climatic geomorphology study of the Sierras Pampeanas Andes, northwestern Argentina  

NASA Technical Reports Server (NTRS)

A proposed analysis of Shuttle Imaging Radar-B (SIR-B) data extends current research in the Sierras Pampeanas and the Puna of northwestern Argentina to the determination - by the digital analysis of mountain-front sinuousity - of the relative age and amount of fault movement along mountain fronts of the late-Cenozoic Sierras Pampeanas basement blocks; the determination of the age and history of the boundary across the Andes at about 27 S latitude between continuing volcanism to the north and inactive volcanism to the south; and the determination of the age and extent of Pleistocene glaciation in the High Sierras, as well as the comparative importance of climatic change and tectonic movements in shaping the landscape. The integration of these studies into other ongoing geology projects contributes to the understanding of landform development in this active tectonic environment and helps distinguish between climatic and tectonic effects on landforms.

Bloom, A. L.; Strecker, M. R.; Fielding, E. J.

1984-01-01

420

The phytoplankton bloom in the northwestern Arabian Sea during the southwest monsoon of 1979  

NASA Technical Reports Server (NTRS)

The present study investigates the biological variability of the northwestern Arabian Sea during the 1979 southwest monsoon by the synthesis of satellite ocean color remote sensing with an analysis of in situ hydrographic and meteorological data sets and the results of wind-driven modeling of upper-ocean circulation. The phytoplankton bloom peaked during August-September, extended from the Oman coast to about 65 deg E, and lagged behind the development of open-sea upwelling by at least 1 mo. The pigment distributions, hydrographic data, and model results all suggest that the boom was driven by spatially distinct upward nutrient fluxes to the euphotic zone forced by the physical processes of coastal upwelling and offshore Ekman pumping. Coastal upwelling was evident from May through September, yielded the most extreme concentrations of phytoplankton biomass, and, along the Arabian coast, was limited to the continental shelf in the promotion of high concentrations of phytoplankton.

Brock, John C.; Mcclain, Charles R.; Luther, Mark E.; Hay, William W.

1991-01-01

421

Depositional history of polychlorinated biphenyls in a dated sediment core from the northwestern Arabian Gulf.  

PubMed

The vertical distribution of polychlorinated biphenyls (PCBs) was measured in a dated sediment core from the northwestern Arabian Gulf to reconstruct their depositional history. The downcore profile showed an increase in concentrations from depth to a subsurface maximum of approximately 1,500 pg g(-1) in approximately 1991, followed by an exponential decrease to the sediment-water interface. Current concentrations of ?PCBs are similar to levels predating the episodic input of PCBs in sediments dated coincident with the 1991 Arabian Gulf war. The spike in ?PCB concentrations during the war may be related to the destruction of PCB-laden transformers during the conflict. The 15-fold decrease in ?PCB concentrations from the period of maximum flux to prewar levels suggests that the factors delivering PCBs to sediments at present are similar to those that that existed before the war-related inputs. PMID:22218707

Gevao, Bondi; Aba, Abdul Aziz; Al-Ghadban, Abdul Nabi; Uddin, Saif

2012-05-01

422

Determination of the trophic situation in Gheshlagh reservoir (North-Western Iran).  

PubMed

'Trophic state' is often used to classify aquatic ecosystems according to biotic productivity. Carlson trophic state indices were used to assess the trophic situation in Gheshlagh reservoir (North-Western Iran), on which a dam was constructed three decades ago. Using data from a one-year surface sampling, a comparison of the trophic state index (TSI), between four sampling points in the reservoir and one sampling point under the dam, was performed. The results of the TSI calculated based on chlorophyll a (chl. a) concentration and Secchi depth showed that the aquatic environment in the reservoir is eutrophied (50 < TSI < 80), while it is mesotrophic (40 < TSI < 50) under the dam. Moreover, the measured concentrations of chl. a and phosphate were consistent with the available data ranges on eutrophication. In addition, it was shown that algal biomass bloom occurred at the end of spring, all over the sampling points. PMID:22629625

Rezaei, Fariba; Zadeh, Hamed Ghader; Van Damme, Patrick

2012-01-01

423

Water vapor and surface observations in northwestern Mexico during the 2004 NAME Enhanced Observing Period  

NASA Astrophysics Data System (ADS)

We report on precipitable water vapor (PWV) from a Global Positioning System (GPS) receiver and surface meteorological network during the 2004 North American Monsoon Experiment (NAME) in northwestern Mexico. The monsoon onset is evident as a large PWV increase over several days beginning July 1. Data in the Sierra Madre Occidental (SMO) foothills reveal a dynamical transition in mid-August from smaller, sub-synoptic scale to larger, synoptic scale moisture structure. During the Sub-synoptic phase in the SMO foothills, a positive feedback operates where near-daily precipitation supplied moisture maintains 15% higher surface mixing ratios that lower the lifting condensation level facilitating initiation of moist convection. Along the western edge of the SMO, precipitation typically occurs hours after the local temperature maximum, triggered by westward propagating convective disturbances. Precipitation is typically preceded by a rapid rise in PWV and sharp decrease in surface temperature, implying models must include moist convective downdrafts in the NAM area.

Kursinski, E. R.; Bennett, R. A.; Gochis, D.; Gutman, S. I.; Holub, K. L.; Mastaler, R.; Minjarez Sosa, C.; Minjarez Sosa, I.; van Hove, T.

2008-02-01

424

Water environmental degradation of the Heihe River Basin in arid northwestern China.  

PubMed

Water environmental degradation is a major issue in the Heihe River Basin belonging to the inland river basin of temperate arid zone in northwestern China. Mankind's activities, such as dense population and heavy dependence on irrigated agriculture, place immense pressure on available and limited water resources during the last century, especially the recent five decades. An investigation on the water environmental degradation in the Heihe River Basin and analysis of its causation were conducted. The results indicated that water environmental changes in the whole basin were tremendous mostly in the middle reaches, which reflected in surface water runoff change, decline of groundwater table and degeneration of surface water and groundwater quality. Some new forms of management based on traditional and scientific knowledge must be introduced to solve problems of water environmental degradation in the Heihe River Basin. PMID:16160787

Qi, Shan-Zhong; Luo, Fang

2005-09-01

425

Phylogeographical analysis of an estuarine fish, Salanx ariakensis (Osmeridae: Salanginae) in the north-western Pacific.  

PubMed

This study extended the geographic coverage of a previous study to explore population genetic structure and demographic history in the Ariake icefish Salanx ariakensis from three populations of continental coastlines and one island population in the north-western Pacific based on a partial sequence of the mitochondrial cytochrome b gene. The S. ariakensis showed high genetic diversity and strong genetic structure. Phylogenetic analysis showed a shallow gene tree with no clear phylogeographical structure. Contiguous range expansion and restricted gene flow were inferred to be main population events by nested-clade analysis. Significant genetic differentiations between populations could be attributable to negligible gene flow by coalescent analysis. High nucleotide diversity of each population was due to geographic mixing of heterogenous haplotypes during lowering sea levels of the Pleistocene. These findings indicate that cycles of geographic isolation and secondary contact happened in the Pleistocene glacial-interglacial cycles shaping genetic structure and population demography of S. ariakensis. PMID:20738543

Hua, X; Wang, W; Yin, W; He, Q; Jin, B; Li, J; Chen, J; Fu, C

2009-08-01

426

Use of domesticated pigs by Mesolithic hunter-gatherers in northwestern Europe  

PubMed Central

Mesolithic populations throughout Europe used diverse resource exploitation strategies that focused heavily on collecting and hunting wild prey. Between 5500 and 4200 cal BC, agriculturalists migrated into northwestern Europe bringing a suite of Neolithic technologies including domesticated animals. Here we investigate to what extent Mesolithic Ertebølle communities in northern Germany had access to domestic pigs, possibly through contact with neighbouring Neolithic agricultural groups. We employ a multidisciplinary approach, applying sequencing of ancient mitochondrial and nuclear DNA (coat colour-coding gene MC1R) as well as traditional and geometric morphometric (molar size and shape) analyses in Sus specimens from 17 Neolithic and Ertebølle sites. Our data from 63 ancient pig specimens show that Ertebølle hunter-gatherers acquired domestic pigs of varying size and coat colour that had both Near Eastern and European mitochondrial DNA ancestry. Our results also reveal that domestic pigs were present in the region ~500 years earlier than previously demonstrated.

Krause-Kyora, Ben; Makarewicz, Cheryl; Evin, Allowen; Flink, Linus Girdland; Dobney, Keith; Larson, Greger; Hartz, Sonke; Schreiber, Stefan; von Carnap-Bornheim, Claus; von Wurmb-Schwark, Nicole; Nebel, Almut

2013-01-01

427

Graphically characterizing the movement of a rabid striped skunk epizootic across the landscape in northwestern Wyoming.  

PubMed

A striped skunk (Mephitis mephitis) rabies epizootic in northwestern Wyoming was studied from the Index Case in 1988 to the last case in 1993, and possibly is the first rabies epizootic in a previously rabies-free zone monitored from beginning to end. The 843 km(2) study area comprised skunk habitat along 90 km of Shoshone River's floodplain from Bighorn Lake upstream to Cody. Of 1,015 skunks tested, 215 were rabies-positive. Integrating spatial and temporal data from positive cases, we analyzed the epizootic's movements and dynamics at 6-month intervals using multivariate movement maps, a new multivariate descriptive methodology presented here to demonstrate the epizootic's directional flow, while illustrating areas with higher case densities (i.e., wave crests). This approach should help epidemiologists and public health officials to better understand future rabies epizootics. PMID:23812724

Ramey, Craig A; Mills, Kenneth W; Fischer, Justin W; McLean, Robert G; Fagerstone, Kathleen A; Engeman, Richard M

2013-09-01

428

Acadian remobilization of a Taconian ophiolite, Hare Bay allochthon, northwestern Newfoundland  

SciTech Connect

The Hare Bay fault is a major subhorizontal detachment at the base of the ophiolitic St. Anthony Complex in the Hare Bay allochthon, northwestern Newfounland. The fault is a postmetamorphic brittle detachment that truncates footwall structures related to both initial Ordovician (Taconian) assembly of the allochthon and subsequent Silurian-Devonian (Acadian) deformation. Although previously mapped as a thrust, the fault has an extensional rather than a contractional geometry; it cuts downsection to the west in the direction of transport, and it juxtaposes a hanging-wall sequence that contains little or no Acadian deformation against a footwall sequence that was pervasively deformed during the Acadian orogeny. The St. Anthony Complex lies on the western margin of the Acadian deformed zone. Its final emplacement, through movement on the Hare Bay fault, probably occurred through extensional faulting during gravitational collapse of the Acadian mountain front.

Cadwood, P.A. (Memorial Univ. of Newfoundland, St. Johns's (Canada))

1989-03-01

429

Increasing N abundance in the northwestern Pacific Ocean due to atmospheric nitrogen deposition.  

PubMed

The relative abundance of nitrate (N) over phosphorus (P) has increased over the period since 1980 in the marginal seas bordering the northwestern Pacific Ocean, located downstream of the populated and industrialized Asian continent. The increase in N availability within the study area was mainly driven by increasing N concentrations and was most likely due to deposition of pollutant nitrogen from atmospheric sources. Atmospheric nitrogen deposition had a high temporal correlation with N availability in the study area (r = 0.74 to 0.88), except in selected areas wherein riverine nitrogen load may be of equal importance. The increase in N availability caused by atmospheric deposition and riverine input has switched extensive parts of the study area from being N-limited to P-limited. PMID:21940860

Kim, Tae-Wook; Lee, Kitack; Najjar, Raymond G; Jeong, Hee-Dong; Jeong, Hae Jin

2011-10-28

430

[Trophic webs of reef fishes in northwestern Cuba. I. Stomach contents].  

PubMed

Trophic webs of reef fishes in northwestern Cuba. I. Stomach contents. Studies on the reef fishes of Cuba are not rare, but most have two basic limitations: small sample sizes and exclusion of small species. Our study sampled more species and larger samples in the sublitoral region of Havana city (23 degrees 7.587' N, 82 degrees 25.793' W), 2-18 m deep. We collected fish weekly from October 2004 through February 2006 with traps and harpoon. Overfishing has modified the fish communities. We used the relative importance index to describe the diets of carnivore and omnivore species, and a modification of the relative abundance method for the herbivores and sponge-eating species. The main food items are benthonic crustaceans (crabs, shrimp, copepods) and bony fish (mainly demersal species). Most species are eurifagous and thus, less affected by anthropic disturbance than specialist feeders. PMID:19256427

Hernández, Ivet; Aguilar, Consuelo; González Sanón, Gaspar

2008-06-01

431

Ecological niches of three teuthophageous odontocetes in the northwestern Mediterranean Sea  

NASA Astrophysics Data System (ADS)

In the northwestern Mediterranean Sea, sperm whales, pilot whales and Risso's dolphins prey exclusively or preferentially on cephalopods. In order to evaluate their competition, we modelled their habitat suitability with the Ecological Niche Factor Analysis (ENFA) and compared their ecological niches using a discriminant analysis. We used a long term (1995-2005) small boat data set, with visual and acoustic (sperm whale) detections. Risso's dolphin had the shallowest and the more spatially restricted principal habitat, mainly located on the upper part of the continental slope (640 m mean depth). With a wider principal habitat, at 1750 m depth in average, the sperm whale used a deeper part of the slope as well as the closest offshore waters. Finally, the pilot whale has the most oceanic habitat (2500 m mean depth) mainly located in the central Ligurian Sea and Provençal basin. Therefore, potential competition for food between these species may be reduced by the differentiation of their habitats.

Praca, E.; Gannier, A.

2008-02-01

432

Late Devonian sedimentary record of the Paleotethys Ocean - The Mae Sariang section, northwestern Thailand  

NASA Astrophysics Data System (ADS)

An 11 m thick condensed sequence of Late Devonian limestones in northwestern Thailand exhibits faunal associations and sedimentological-/microfacies data which are indicative of a pelagic facies setting. The entire long-ranging section is completely free from clastic input. Similar successions are known worldwide in a few sections only. The Mae Sariang section is characterised by low sedimentation rates as recognised by a number of hardgrounds, neptunian dikes and Fe/Mn crusts. The succession comprises a number of pelagic faunal elements e.g. conodonts, cephalopods and pelagic ostracodes. The fauna records rare macrofossils and the faunal diversity is low. The very condensed section ranges from the Late rhenana to praesulcata conodont biozones, but contains some global events as undoubtedly shown by biostratigraphical and carbon-isotope results (including major Kellwasser and Hangenberg biotic crises). In terms of plate tectonics this important succession most probably belongs to the Inthanon Zone comprising remnants of the Paleotethys Ocean.

Königshof, P.; Savage, N. M.; Lutat, P.; Sardsud, A.; Dopieralska, J.; Belka, Z.; Racki, G.

2012-06-01

433

Ecological niche of three teuthophageous odontocetes in the northwestern Mediterranean Sea  

NASA Astrophysics Data System (ADS)

In the northwestern Mediterranean Sea, sperm whales, pilot whales and Risso's dolphins prey on cephalopods exclusively or preferentially. In order to evaluate their competition, we modelled their habitat suitability with the Ecological Niche Factor Analysis (ENFA) and compared their ecological niche using a discriminant analysis. We used a long term (1995-2005) small boat data set, with visual and acoustic (sperm whale) detections. Risso's dolphin had the shallowest and the more spatially restricted principal habitat, mainly located on the upper part of the continental slope (640 m mean depth). With a wider principal habitat, at 1750 m depth in average, the sperm whale used a deeper part of the slope as well as close offshore waters. Finally, the pilot whale has the most oceanic habitat (2500 m mean depth) mainly located in the central Ligurian Sea and Provençal basin. Therefore, potential competition for food between these species may be reduced by the differentiation of their ecological niches.

Praca, E.; Gannier, A.

2007-10-01

434

Weather forecast in north-western Greece: RISKMED warnings and verification of MM5 model  

NASA Astrophysics Data System (ADS)

The meteorological model MM5 is applied operationally for the area of north-western Greece for one-year period (1 June 2007-31 May 2008). The model output is used for daily weather forecasting over the area. An early warning system is developed, by dividing the study area in 16 sub-regions and defining specific thresholds for issuing alerts for adverse weather phenomena. The verification of the model is carried out by comparing the model results with observations from three automatic meteorological stations. For air temperature and wind speed, correlation coefficients and biases are calculated, revealing that there is a significant overestimation of the early morning air temperature. For precipitation amount, yes/no contingency tables are constructed for 4 specific thresholds and some categorical statistics are applied, showing that the prediction of precipitation in the area under study is generally satisfactory. Finally, the thunderstorm warnings issued by the system are verified against the observed lightning activity.

Bartzokas, A.; Kotroni, V.; Lagouvardos, K.; Lolis, C. J.; Gkikas, A.; Tsirogianni, M. I.

2010-02-01

435