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Sample records for cuyania terrane northwestern

  1. Grenvillean sutures zones in the northern portion of the Cuyania terrane, Republica Argentina. geophysical evidence

    International Nuclear Information System (INIS)

    Chernicoff, C.; Vujovich, G.

    2004-01-01

    In the northern portion of the Cuyania terrane there is geophysical evidence for the ocurrence of two ancient WNW suture zones, corresponding to the Guandacol and Vinchina lineaments. The location of these sutures is consistent with analogous structures in Laurentia, in the Ouachita embayment region, where the Grenvillean orogen trends WNW. It is argued that the WNW transform faults pertaining to the Ouachita rift would have developed as a result of a reactivation of compressional structures of identical orientation associated to the accretion of Grenvillean terranes. The Guandacol and Vinchina lineaments would have been in physical continuity with analogous megastructures in the Ouachita embayment region, and they both would have originated as compressional structures, later reactivated as transcurrent fault zones during the late Proterozoic early Paleozoic. The interpretation of the Guandacol and Vinchina lineaments as Grenvillean suture zones would add more complexity to the Cuyania terrane, with respect to what has been described up to now; they could precede the amalgamation of the Pie de Palo and Precordillera terranes (constituents of the Cuyania composite terrane) [es

  2. High resolution crustal structure for the region between the Chilenia and Cuyania terrane above the Pampean flat slab of Argentina from local receiver function and petrological analyses

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    Ammirati, J. B.; Alvarado, P. M.; Pérez, S. B.; Beck, S. L.; Porter, R. C.; Zandt, G.

    2015-12-01

    Jean-Baptiste Ammirati 1,Sofía Perez 1, Patricia Alvarado 1, Susan L. Beck 2, Ryan Porter 3 and George Zandt 2(1) CIGEOBIO-CONICET, Universidad Nacional de San Juan, Argentina (2) The University of Arizona, USA (3) Northern Arizona University, USA At ~31ºS, The subduction of the Nazca plate under the South American plate presents along-strike variations of its dip angle referred to the Chilean-Pampean flat slab. Geological observations suggest that the regional crustal structure is inherited from the accretion of different terranes at Ordovician times and later reactivated during Andean compression since Miocene. Geophysical observations confirmed that the structure is extending in depth with décollement levels that accommodate crustal shortening in the region. In order to get a better insight on the shallow tectonics we computed high frequency local receiver functions from slab seismicity (~100 km depth). Local earthquakes present a higher frequency content that permits a better vertical resolution. Using a common conversion point (CCP) stacking method we obtained cross sections showing high-resolution crustal structure in the western part of the Pampean flat slab region, at the transition between the Precordillera and the Frontal Cordillera. Our results show a well-defined structure and their lateral extent for both units down to 80 km depth. In good agreement with previous studies, our higher resolution images better identify very shallow discontinuities putting more constraints on the relationships with the regional structural geology. Recent petrological analyses combined with RF high-resolution structure also allow us to better understand the regional crustal composition. Interestingly, we are able to observe a shifting structure beneath the Uspallata-Calingasta Valley, highlighting the differences in terms of crustal structure between the Precordillera and the Frontal Cordillera. Previously determined focal mechanisms in the region match well this

  3. The metallogeny of Late Triassic rifting of the Alexander terrane in southeastern Alaska and northwestern British Columbia

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    Taylor, C.D.; Premo, W.R.; Meier, A.L.; Taggart, J.E.

    2008-01-01

    A belt of unusual volcanogenic massive sulfide (VMS) occurrences is located along the eastern margin of the Alexander terrane throughout southeastern Alaska and northwestern British Columbia and exhibits a range of characteristics consistent with a variety of syngenetic to epigenetic deposit types. Deposits within this belt include Greens Creek and Windy Craggy, the economically most significant VMS deposit in Alaska and the largest in North America, respectively. The occurrences are hosted by a discontinuously exposed, 800-km-long belt of rocks that consist of a 200- to 800-m-thick sequence of conglomerate, limestone, marine elastic sedimentary rocks, and tuff intercalated with and overlain by a distinctive unit of mafic pyroclastic rocks and pillowed flows. Faunal data bracket the age of the host rocks between Anisian (Middle Triassic) and late Norian (late Late Triassic). This metallogenic belt is herein referred to as the Alexander Triassic metallogenic belt. The VMS occurrences show systematic differences in degree of structural control, chemistry, and stratigraphic setting along the Alexander Triassic metallogenic belt that suggest important spatial or temporal changes in the tectonic environment of formation. At the southern end of the belt, felsic volcanic rocks overlain by shallow-water limestones characterize the lower part of the sequence. In the southern and middle portion of the belt, a distinctive pebble conglomerate marks the base of the section and is indicative of high-energy deposition in a near slope or basin margin setting. At the northern end of the belt the conglomerates, limestones, and felsic volcanic rocks are absent and the belt is composed of deep-water sedimentary and mafic volcanic rocks. This northward change in depositional environment and lithofacies is accompanied by a northward transition from epithermal-like structurally controlled, discontinuous, vein- and pod-shaped, Pb-Zn-Ag-Ba-(Cu) occurrences with relatively simple mineralogy

  4. Stable Isotope Evidence for a Complex Fluid Evolution of the Northwestern British Columbia Coast Ranges Related to Terrane Accretion

    Science.gov (United States)

    Moertle, J.; Holk, G. J.

    2015-12-01

    Stable isotope geochemistry reveals a complex fluid evolution for the Western Metamorphic Belt (WMB), Coast Ranges Batholith (CRB), Central Gneiss Complex (CGC) and Coast Ranges Megalineament (CRM). These fluids are a product of a complex tectonic history related to terrane accretion that includes oblique convergence, metamorphism, magmatism, and orogenic collapse. From W-to-E, these fluid systems are as follows. High-pressure greenschist-to-amphibolite facies metasedimentary rocks of the WMB record variable mineral δD (-61 to -104‰) and δ18O (e.g., quartz +9.6 to +13.4‰) values with multiple minerals in apparent isotopic equilibrium (T ~ 450-550°C) suggest a low W/R system dominated by metamorphic fluids. Variable and non-equilibrium δD (-53 to -143‰) and δ18O (e.g., biotite +2.3 to +5.3‰) values from diorites of the Quottoon pluton affected by the ductile CRM suggest a complex evolution that involved both metamorphic and meteoric-hydrothermal fluids in this dextral shear zone; these results differ from those 300 km along strike to the north that documented only metamorphic fluids in the CRM (Goldfarb et al., 1988). Our data and those of Magaritz and Taylor (1976) from granulite facies metasediments of the CGC and plutons of the western CRB reveal homogeneous δD values (-62 to -78‰) and a restricted range of δ18O values (e.g., quartz +8.5 to +11.5‰) with all minerals in equilibrium at T > 570°C indicate a system dominated by magmatic fluids. Calculated whole-rock δ18O values (~ +7‰) for the Quottoon pluton and CRB intrusive rocks suggest a mantle origin for these magmas. Reinterpretation of very low δD (< -150‰) and quartz-feldspar δ18O pairs that display extreme disequilibrium (feldspar δ18O values as low as -5‰) from the Ponder pluton, eastern CRB, and Hazelton Group point reveals that the major meteoric-hydrothermal system that affected these rocks was related to Eocene detachment faulting along the Shames Lake fault system, a

  5. Devonian granitoids and their hosted mafic enclaves in the Gorny Altai terrane, northwestern Central Asian Orogenic Belt: crust-mantle interaction in a continental arc setting

    Science.gov (United States)

    Chen, Ming; Sun, Min

    2016-04-01

    Granitoids are a major component in the upper continental crust and hold key information on how did the continental crust grow and differentiate. This study focuses on the Yaloman intrusive complex from the Gorny Altai terrane, northwestern Central Asian Orogenic Belt (CAOB). The association of granitoids and mafic enclaves can provide important clues on the source nature, petrogenetic processes and geodynamic setting of the Yaloman intrusive complex, which in turn will shed light on the crustal evolution in the northwestern CAOB. Zircon U-Pb dating shows that the granitoids, including quartz diorites and granodiorites, were emplaced in ca. 389-387 Ma. The moderate Na2O + K2O contents and low A/CNK values indicate that these rocks belong to the sub-alkaline series with metaluminous to weakly peraluminous compositions. The granitoids yield two-stage zircon Hf model ages of ca. 0.79-1.07 Ga and whole-rock Nd model ages of ca. 0.90-0.99 Ga, respectively, implying that they were mainly sourced from Neoproterozoic juvenile crustal materials. The mafic enclaves show an almost identical crystallization age of ca. 389 Ma. The identification of coarse-grained xenocrysts and acicular apatites, together with the fine-grained texture, makes us infer that these enclaves are likely to represent magmatic globules commingled with the host magmas. The low SiO2 and high MgO contents of the mafic enclaves further suggest that substantial mantle-derived mafic melts were probably involved in their formation. Importantly, the SiO2 contents of the granitoids and mafic enclaves are well correlated with other major elements and most of the trace elements. Also a broadly negative correlation exists between the SiO2 contents and whole-rock epsilon Nd (390 Ma) values of the granitoids. Given the observation of reversely zoned plagioclases within the granitoids and the common occurrence of igneous mafic enclaves, we propose that magma mixing probably played an important role in the formation

  6. Siberia, the wandering northern terrane, and its changing geography through the Palaeozoic

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    Cocks, L. Robin M.; Torsvik, Trond H.

    2007-05-01

    The old terrane of Siberia occupied a very substantial area in the centre of today's political Siberia and also adjacent areas of Mongolia, eastern Kazakhstan, and northwestern China. Siberia's location within the Early Neoproterozoic Rodinia Superterrane is contentious (since few if any reliable palaeomagnetic data exist between about 1.0 Ga and 540 Ma), but Siberia probably became independent during the breakup of Rodinia soon after 800 Ma and continued to be so until very near the end of the Palaeozoic, when it became an integral part of the Pangea Supercontinent. The boundaries of the cratonic core of the Siberian Terrane (including the Patom area) are briefly described, together with summaries of some of the geologically complex surrounding areas, and it is concluded that all of the Palaeozoic underlying the West Siberian Basin (including the Ob-Saisan Surgut area), Tomsk Terrane, Altai-Sayan Terranes (including Salair, Kuznetsk Alatau, Batenov, Kobdin and West Sayan), Ertix Terrane, Barguzin Terrane, Tuva-Mongol Terrane, Central Mongolia Terrane Assemblage, Gobi Altai and Mandalovoo Terranes, Okhotsk Terrane and much of the Verkhoyansk-Kolyma region all formed parts of peri-Siberia, and thus rotated with the main Siberian Craton as those areas were progressively accreted to the main Siberian Terrane at various times during the latest Neoproterozoic and Palaeozoic. The Ertix Terrane is a new term combining what has been termed the "Altay Terrane" or "NE Xinjiang" area of China, and the Baytag, Baaran and Bidz terranes of Mongolia. The Silurian Tuvaella brachiopod fauna is restricted only to today's southern parts of peri-Siberia. Thus, allowing for subsequent rotation, the fauna occurs only in the N of the Siberian Terrane, and, as well as being a helpful indicator of what marginal terranes made up peri-Siberia, is distinctive as being the only Silurian fauna known from northern higher latitudes globally. In contrast, the other terranes adjacent to peri

  7. Gravity signatures of terrane accretion

    Science.gov (United States)

    Franco, Heather; Abbott, Dallas

    1999-01-01

    In modern collisional environments, accreted terranes are bracketed by forearc gravity lows, a gravitational feature which results from the abandonment of the original trench and the initiation of a new trench seaward of the accreted terrane. The size and shape of the gravity low depends on the type of accreted feature and the strength of the formerly subducting plate. Along the Central American trench, the accretion of Gorgona Island caused a seaward trench jump of 48 to 66 km. The relict trench axes show up as gravity lows behind the trench with minimum values of -78 mgal (N of Gorgona) and -49 mgal (S of Gorgona) respectively. These forearc gravity lows have little or no topographic expression. The active trench immediately seaward of these forearc gravity lows has minimum gravity values of -59 mgal (N of Gorgona) and -58 mgal (S of Gorgona), respectively. In the north, the active trench has a less pronounced gravity low than the sediment covered forearc. In the Mariana arc, two Cretaceous seamounts have been accreted to the Eocene arc. The northern seamount is most likely a large block, the southern seamount may be a thrust slice. These more recent accretion events have produced modest forearc topographic and gravity lows in comparison with the topographic and gravity lows within the active trench. However, the minimum values of the Mariana forearc gravity lows are modest only by comparison to the Mariana Trench (-216 mgal); their absolute values are more negative than at Gorgona Island (-145 to -146 mgal). We speculate that the forearc gravity lows and seaward trench jumps near Gorgona Island were produced by the accretion of a hotspot island from a strong plate. The Mariana gravity lows and seaward trench jumps (or thrust slices) were the result of breaking a relatively weak plate close to the seamount edifice. These gravity lows resulting from accretion events should be preserved in older accreted terranes.

  8. The Svalbard Caledonides - a collage of Laurentian, Timanian and exotic terranes assembled by Silurian - Late (?) Devonian transcurrent faulting.

    Science.gov (United States)

    Andresen, Arild; Gasser, Deta

    2014-05-01

    New field and geochronological data from NE Greenland and Svalbard indicate that most of the sub-terranes making up the Svalbard Caledonides (Eastern, Northwestern and Southwestern Terranes) are derived from Laurentias eastern margin. The Neoproterozoic deposits of the Eastern Terrane (Nordaustlandet) show an almost one to one correlation with the Late Neoproterozoic Eleonore Bay Supergroup in NE Greenland. Great similarities also exist between the substratum to the Neoproterozoic deposits in the two areas. The "Barentsian plate/continent" is interpreted to be derived from Laurentias eastern margin Lithologic similarities also exist between parts of the Northwestern Terrane and NE Greenland. The geologic evolution of Svalbard`s Southwestern Terrane, with subduction complexes and Late Neoproterozoic intrusives (Timanian ?) is poorly understood. It will, however, be argued that there is no need to invoke considerable right lateral strike-slip movement of the Motalefjellet subduction complex and related rocks from a position in Arctic Canada to their present position within the Southwestern Terrane, as proposed by some authors. The structural grain of the Svalbard Caledonides, oblique to East Greenland and Scandinavian Caledonides, as well as the Ellesmerian Orogen, is interpreted to be due to counter-clockwise rotation (c. 45o) of the Caledonian trend. A counter-clockwise rotation is to be expected when the northward moving terranes reached the E-W trending Franklinian Basin north of Greenland/Laurentia, which in Early Devonian time had not yet started to close. The model predicts that there should be a dramatic change in the Caledonian structural grain somewhere south of Bjørnøya. It is furthermore speculated that the fan-shaped orientation of Late Paleozoic rift basins in the Western Barents Sea is controlled by reactivation of the rotated structural trend (e.g. Billefjorden Fault Zone and Billefjorden Trough).

  9. Geochemical Constraints for Mercury's PCA-Derived Geochemical Terranes

    Science.gov (United States)

    Stockstill-Cahill, K. R.; Peplowski, P. N.

    2018-05-01

    PCA-derived geochemical terranes provide a robust, analytical means of defining these terranes using strictly geochemical inputs. Using the end members derived in this way, we are able to assess the geochemical implications for Mercury.

  10. Lower precambrian of the Keivy Terrane, Northeastern Baltic Shield: A stratigraphic succession or a collage of tectonic sheets?

    Science.gov (United States)

    Balagansky, V. V.; Raevsky, A. B.; Mudruk, S. V.

    2011-03-01

    The Keivy Terrane in the northeastern Baltic Shield appreciably differs from the adjacent tectonic blocks. In the northwestern part of this terrane (the Serpovidny Range), an outlier of Paleoproterozoic supracrustal rocks called the Serpovidny structure is surrounded by Archean (?) Keivy high-alumina paraschists. As follows from structural and magnetic data, the Paleoproterozoic rocks are deformed into a tight sheath fold 8 × 2 km in size at the surface and 5 km in length along the sheath axis. Faults parallel to the boundaries of the layers and locally cutting them off at an acute angle are involved in folding as well. The outer boundaries of the Serpovidny structure are tectonic. This structure is complementary to a larger tectonic lens composed of the Keivy mica schists. It is concluded that all of the supracrustal rocks of the Serpovidny Range are in fact tectonic sheets and lenses deformed into sheath folds. The literature data show that kilometer-scale sheath folds occur throughout the Keivy paraschist belt and most likely were formed owing to thrusting of the Murmansk Craton onto the Keivy Terrane in the south-southwestern direction. Foliation and lineation related to thrusting have been established in the Archean silicic metavolcanics and peralkaline granites occupying the most part of the terrane. In contrast, the granitoids and gabbroanorthosites of the Archean basement, which form a block 90 × 20 km in the southwestern Keivy Terrane, were not affected by Paleoproterozoic deformation. In other words, a detached assembly of tectonic sheets composed of the upper and middle crustal rocks that underwent deformation at the initial stage of the Paleoproterozoic Lapland-Kola Orogeny and the Archean basement, which is free of this deformation, are distinguished. The depth of detachment is estimated at 20-25 km. The detachment of the upper and middle crust in the Keivy Terrane and its position in the structure of the Baltic Shield are consistent with a

  11. Circum-North Pacific tectonostratigraphic terrane map

    Science.gov (United States)

    Nokleberg, Warren J.; Parfenov, Leonid M.; Monger, James W.H.; Baranov, Boris B.; Byalobzhesky, Stanislav G.; Bundtzen, Thomas K.; Feeney, Tracey D.; Fujita, Kazuya; Gordey, Steven P.; Grantz, Arthur; Khanchuk, Alexander I.; Natal'in, Boris A.; Natapov, Lev M.; Norton, Ian O.; Patton, William W.; Plafker, George; Scholl, David W.; Sokolov, Sergei D.; Sosunov, Gleb M.; Stone, David B.; Tabor, Rowland W.; Tsukanov, Nickolai V.; Vallier, Tracy L.; Wakita, Koji

    1994-01-01

    The companion tectonostratigraphic terrane and overlap assemblage of map the Circum-North Pacific presents a modern description of the major geologic and tectonic units of the region. The map illustrates both the onshore terranes and overlap volcanic assemblages of the region, and the major offshore geologic features. The map is the first collaborative compilation of the geology of the region at a scale of 1:5,000,000 by geologists of the Russian Far East, Japanese, Alaskan, Canadian, and U.S.A. Pacific Northwest. The map is designed to be a source of geologic information for all scientists interested in the region, and is designed to be used for several purposes, including regional tectonic analyses, mineral resource and metallogenic analyses (Nokleberg and others, 1993, 1994a), petroleum analyses, neotectonic analyses, and analyses of seismic hazards and volcanic hazards. This text contains an introduction, tectonic definitions, acknowledgments, descriptions of postaccretion stratified rock units, descriptions and stratigraphic columns for tectonostratigraphic terranes in onshore areas, and references for the companion map (Sheets 1 to 5). This map is the result of extensive geologic mapping and associated tectonic studies in the Russian Far East, Hokkaido Island of Japan, Alaska, the Canadian Cordillera, and the U.S.A. Pacific Northwest in the last few decades. Geologic mapping suggests that most of this region can be interpreted as a collage of fault-bounded tectonostratigraphic terranes that were accreted onto continental margins around the Circum-

  12. North America as an exotic terrane'' and the origin of the Appalachian--Andean Mountain system

    Energy Technology Data Exchange (ETDEWEB)

    Dalziel, I.W.D; Gahagan, L.M. (Univ. of Texas, Austin, TX (United States). Inst. for Geophysics); Dalla Salda, L.H. (Univ. Nacional de La Plata, La Plata (Argentina). Centro de Investigaciones Geologicas)

    1992-01-01

    North America was sutured to Gondwana in the terminal Alleghanian event of Appalachian orogenesis, thus completing the late Paleozoic assembly of Pangea. The suggestion that the Pacific margins of East Antarctica-Australia and Laurentia may have been juxtaposed during the Neoproterozoic prompts reevaluation of the widely held assumptions that the ancestral Appalachian margin rifted from northwestern Africa during the earliest Paleozoic opening of Iapetus, and remained juxtaposed to that margin, even though widely separated from it at times, until the assembly of Pangea. The lower Paleozoic carbonate platform of northwestern Argentina has been known for a long time to contain Olenellid trilobites of the Pacific or Columbian realm. Although normally regarded as some kind of far-travelled terrane that originated along the Appalachian margin of Laurentia, it has recently been interpreted as a fragment detached from the Ouachita embayment of Laurentia following Taconic-Famatinian collision with Gondwana during the Ordovician. The Oaxaca terrane of Mexico, on the other hand, contains a Tremadocian trilobite fauna of Argentine-Bolivian affinities, and appears to have been detached from Gondwana following the same collision. The Wilson cycle'' of Iapetus ocean basin opening and closing along the Appalachian and Andean orogens may have involved more than one such continental collision during clockwise drift of Laurentia around South America following late Neoproterozoic to earliest Cambrian separation. Together with the collisions of baltic and smaller terranes with Laurentia, this could explain the protracted Paleozoic orogenic history of both the Appalachian and proto-Andean orogens.

  13. Linking Tengchong Terrane in SW Yunnan with Lhasa Terrane in southern Tibet through magmatic correlation

    Science.gov (United States)

    Xie, Jincheng; Zhu, Dicheng; Dong, Guochen; Zhao, Zhidan; Wang, Qing

    2016-04-01

    New zircon U-Pb data, along with the data reported in the literature, reveal five phases of magmatic activity in the Tengchong Terrane since the Early Paleozoic with spatial and temporal variations summarized as: Cambrian-Ordovician (500-460 Ma) to the eastern, minor Triassic (245-206 Ma) in the eastern and western, abundant Early Cretaceous (131-114 Ma) in the eastern, extensive Late Cretaceous (77-65 Ma) in the central, and Paleocene-Eocene (65-49 Ma) in the central and western Tengchong Terrane, in which the Cretaceous-Eocene magmatism was migrated from east to west (Xu et al., 2012). The increased zircon eHf(t) of the Early Cretaceous granitoids from -12.3 to -1.4 at ca. 131-122 Ma to -4.6 to +7.1 at ca. 122-114 Ma identified for the first time in this study and the magmatic flare-up at ca. 53 Ma in the central and western Tengchong Terrane (Wang et al., 2014, Ma et al., 2015) indicate the increased contributions from mantle- or juvenile crust-derived components. The spatial and temporal variations and changing magmatic compositions with time in the Tengchong Terrane closely resemble the Lhasa Terrane in southern Tibet. Such similarities, together with the data of stratigraphy and paleobiogeography (Zhang et al., 2013), enable us to propose that the Tengchong Terrane in SW Yunnan is most likely linked with the Lhasa Terrane in southern Tibet, both of which experience similar tectonomagmatic histories since the Early Paleozoic. References Ma, L.Y., Wang, Y.J., Fan, W.M., Geng, H.Y., Cai, Y.F., Zhong, H., Liu, H.C., Xing, X.W., 2014. Petrogenesis of the early Eocene I-type granites in west Yingjiang (SW Yunnan) and its implication for the eastern extension of the Gangdese batholiths. Gondwana Research 25, 401-419. Wang, Y.J., Zhang, L.M., Cawood, P.A., Ma, L.Y., Fan, W.M., Zhang, A.M., Zhang, Y.Z., Bi, X.W., 2014. Eocene supra-subduction zone mafic magmatism in the Sibumasu Block of SW Yunnan: Implications for Neotethyan subduction and India-Asia collision

  14. Tectonostratigraphic terranes of the frontier circum-Pacific region

    Energy Technology Data Exchange (ETDEWEB)

    Howell, D.G.; Jones, D.L.; Schermer, E.R.

    1983-03-01

    Many major exploration frontiers around the Pacific are in regions where complex geologic relations reflect plate-tectonic processes, crustal mobility, and accretion of exotic terranes. The destruction of the proto-Pacific ocean (Panthalassa) involved accretion of terranes to cratonal regions such as Gondwana and Laurasia. Terranes in southwestern New Zealand and eastern Antarctica were also probably accreted during the Paleozoic. The southern margin of Siberia, extending into China, underwent a protracted period of accretion from the late Precambrian through the early Mesozoic. Mid-Paleozoic accretion is reflected in the Innuitian foldbelt of the Arctic Ocean, the Black Clastic unit of the northern Rocky Mountains, and the Antler orogeny of the western US cordillera. The Mesozoic breakup of Pangaea and the acceleration of subduction aided in the rifting and dispersal of terranes from equatorial paleolatitudes. Fragments of these terranes now compose much of the continental margins of the Pacific basin, including New Zealand, Indochina, southern China, southeast Siberia, the North American cordillera, and South America. Some terranes are presently being further fragmented by post-accretionary dispersion processes such as strike-slip faulting in western North America and Japan. Although the character and distribution of terranes in the western US are fairly well documented, details are needed for other terranes around the Pacific basin. Interpretation of structure and stratigraphy at depth will be aided by more data on the timing of accretion and the nature of deformation associated with accretion and dispersion. Such data are needed for further define specific exploration targets in the circum-Pacific region.

  15. Geochronologic synthesis of the Piedra Alta Terrane, Uruguay

    International Nuclear Information System (INIS)

    Preciozzi, F.; Peel, E.

    2006-01-01

    In the Pre cordillera of Córdoba there are sixteen bands of ductile deformation, which allows tectonic significance assign them to four groups. One of them, which belongs to Deformation Gaza Tunnels, consists of post metamorphic strips uprooting of Orogen Pampeano Cambrian reverse nature, produced by convergent general shear (transpressional), related to collisional stages terrain Posthumous Pampa against Gondwana margin, and famatinian subduction. New radiometric data obtained by the K / Ar method amphiboles and micas allow better narrow activity tectonics of the strip, which would have nucleated after the M2 metamorphic peak (ca. 534 Ma), uprooted the Orogen Cambrian and Ordovician exhumándolo up early (onset of subduction Famatinian), when located the Charquina (474 ​​Ma) granodiorite. The period of tectonic activity FDLT (ca. 64 Ma), coincide with the approach of land Cuyania the Gondwana margin, prior to placement and final collision in the Middle to Late Ordovician. At the same time, in the field Pampeano they would be producing con tractional stages end collision with terrain Pampa the western margin of Gondwana. Subsequently, the FDLT would have cooled to the middle Silurian, when the Sierras de Cordoba and San Luis They continued their exhumation through isotherm muscovite. After cooling this generalized, deformation occurs and Devonian magmatism that penetrativamente affected the Pre cordillera eastern

  16. Effects of silicate weathering on water chemistry in forested, upland, felsic terrane of the USA

    International Nuclear Information System (INIS)

    Stauffer, R.E.; Wittchen, B.D.

    1991-01-01

    The authors use data from the US EPA National Surface Water Survey (NSWS), the USGS Bench-Mark Station monitoring program, and the National Acid Deposition Program (NADP) to evaluate the role of weathering in supplying base cations to surface waters in forested, upland, felsic terrane of the northeastern, northcentral, and northwestern (Idaho batholith) US. Multivariate regression reveals differential effects of discharge on individual base cations and silica, but no secular trend in the Ca/Na denudation rate over 24 yr (1965-1988) for the Wild River catchment in the White Mountains. Because the turn-over time for Na in the soil-exchange complex is only ca. 1.5 yr, the long-term behavior of the ratios Ca/Na and Si/Na in waters leaving this catchment indicates that weathering is compensating for base cation export. In every subregion, Ca and Mg concentrations in lakes are statistically linked to nonmarine Na, but the median Ca/Na ratio is greater than the ratio in local plagioclase. The authors attribute this inequality to nonstoichiometric weathering of calcium in juvenile (formerly glaciated) terrane, not to leaching of exchangeable cations by So 4 because intraregional and cross-regional statistical analysis reveals no effect of atmospherically derived sulfate ion. The median base cation denudation rates (meq m -2 yr -1 ) for these American lake regions are: Maine granites (108); western Adirondack felsic gneiss (85); Vermilion batholith (42); Idaho batholith (52). The regional rates are high enough to compensate for present wet deposition of acidifying anions except in some vulnerable lake watersheds in the western Adirondacks

  17. Upper lower Cambrian (provisional Cambrian Series 2 trilobites from northwestern Gansu Province, China

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    Jan Bergström†

    2014-08-01

    Full Text Available Upper lower Cambrian (provisional Cambrian Series 2 trilobites are described from three sections through the Shuangyingshan Formation in the Beishan area, northwestern Gansu Province, China. The trilobite fauna is dominated by eodiscoid and corynexochid trilobites, together representing at least ten genera: Serrodiscus, Tannudiscus, Calodiscus, Pagetides, Kootenia, Edelsteinaspis, Ptarmiganoides?, Politinella, Dinesus and Subeia. Eleven species are described, of which seven are identified with previously described taxa and four described under open nomenclature. The composition of the fauna suggests biogeographic affinity with Siberian rather than Gondwanan trilobite faunas, and the Cambrian Series 2 faunas described herein and from elsewhere in northwestern China seem to be indicative of the marginal areas of the Siberian palaeocontinent. This suggests that the Middle Tianshan–Beishan Terrane may have been located fairly close to Siberia during middle–late Cambrian Epoch 2.

  18. Gondwanan/peri-Gondwanan origin for the Uchee terrane, Alabama and georgia: Carolina zone or Suwannee terrane(?) and its suture with Grenvillian basement of the Pine Mountain window

    Science.gov (United States)

    Steltenpohl, M.G.; Mueller, P.M.; Heatherington, A.L.; Hanley, T.B.; Wooden, J.L.

    2008-01-01

    The poorly known, suspect, Uchee terrane occupies a critical tectonic position with regard to how and when peri-Gondwanan (Carolina) and Gondwanan (Suwannee) terranes were sutured to Laurentia. It lies sandwiched between Laurentian(?) continental basement exposed in the Pine Mountain window and adjacent buried Gondwanan crust of the Suwannee terrane. The Uchee terrane has been proposed as both a septum of Piedmont rocks that once was continuous across the erosionally breached Pine Mountain window or part of the Carolina zone. To help resolve this issue, we conducted U-Pb (SHRIMP-RG) (sensitive high-resolution ion microprobe-reverse geometry) zircon studies and whole-rock isotopic analyses of principal metasedimentary and metaplutonic units. U-Pb ages for zircons from the Phenix City Gneiss suggest igneous crystallization at ca. 620 Ma, inheritance ca. 1000 to ca. 1700 Ma, and a ca. 300 Ma (Alleghanian) overprint recorded by zircon rims. Zircons from the metasedimentary/metavolcaniclastic Moffits Mill Schist yield bimodal dates at ca. 620 and 640 Ma. The 620 to 640 Ma dates make these rocks age-equivalent to the oldest parts of the Carolina slate belt (Virgilina and Savannah River) and strongly suggest a Gondwanan (Pan-African and/or Trans-Brasiliano) origin for the Uchee terrane. Alternatively, the Uchee terrane may be correlative with metamorphic basement of the Suwannee terrane. The ca. 300 Ma overgrowths on zircons are compatible with previously reported 295 to 288 Ma 40Ar/39Ar hornblende dates on Uchee terrane rocks, which were interpreted to indicate deep tectonic burial of the Uchee terrane contemporaneous with the Alleghanian orogeny recorded in the foreland. Temperature-time paths for the Uchee terrane are similar to that of the Pine Mountain terrane, indicating a minimum age of ca. 295 Ma for docking. In terms of tectono-metamorphic history of the Uchee terrane, it is important to note that no evidence for intermediate "Appalachian" dates (e.g, Acadian or

  19. Geophysical constraints for terrane boundaries in southern Mongolia

    Science.gov (United States)

    Guy, Alexandra; Schulmann, Karel; Munschy, Marc; Miehe, Jean-Marc; Edel, Jean-Bernard; Lexa, Ondrej; Fairhead, Derek

    2014-05-01

    The Central Asian Orogenic Belt (CAOB) is a typical accretionary orogen divided into numerous lithostratigraphic terranes corresponding to magmatic arcs, back arcs, continental basement blocks, accretionary wedges and metamorphic blocks. These terranes should be in theory characterized by contrasting magnetic and gravity signatures thanks to their different petrophysical properties. To test this hypothesis, the stratigraphically defined terranes in southern Mongolia were compared with potential field data to constrain their boundaries and extent. The existence of terranes in southern Mongolia cannot be attested by the uniform geophysical fabrics due to the lack of systematic correspondence between the high/low amplitude and high/low frequency geophysical domains and major terranes. Processed magnetic and gravity grids show that both gravity and magnetic lineaments are E-W trending in the west and correlate with direction of some geological units. In the east, both magnetic and gravity lineaments are disrupted by NE-SW trending heterogeneities resulting in complete blurring of the geophysical pattern. Correlation of magnetic signal with geological map shows that the magnetic highs coincide with late Carboniferous-early Permian volcanic and plutonic belts. The matched-filtering shows good continuity of signal to the depth located along the boundaries of these high magnetic anomalies which may imply presence of deeply rooted tectono-magmatic zones. The axes of high density bodies in the western and central part of the studied CAOB are characterized by periodic alternations of NW-SE trending high frequency and high amplitude gravity anomalies corresponding to late Permian to Triassic cleavage fronts up to 20 km wide. The matched-filtering analysis shows that the largest deformation zones are deeply rooted down to 20 km depth. Such a gravity signal is explained by the verticalization of high density mantle and lower crustal rocks due to localized vertical shearing

  20. Proterozoic biotite Rb-Sr dates in the northwestern part of the Yilgarn Craton, Western Australia

    International Nuclear Information System (INIS)

    Libby, W.G.; De Laeter, J.R.; Armstrong, R.A.

    1999-01-01

    Rb-Sr dating of biotite in the northwestern corner of the Yilgarn Craton identified four areas with distinctive age ranges. Biotite in the northwestern area, which includes the Narryer Terrane and part of the Murchison Terrane, yields reset Rb-Sr dates of ca 1650 Ma. In the western area, along the margin of the craton, biotite has been reset to 629 Ma. Eastward of these areas, mainly in the Murchison Terrane, the modal biotite date is near 2450 Ma, though because of a skewed distribution the mean date is closer to 2300 Ma. Dates in a transition zone between the western and eastern areas range broadly between 2000 and 1000 Ma, averaging about 1775 Ma. The western area and the transition zone are continuous with analogous areas south of the limits of the present study. The 1650 Ma dates in the northwestern area are probably related to plutonic and tectonic activity of similar age in the Gascoyne Province to the north. They may represent cooling after thermal resetting during tectonic loading by southward thrust-stacking of slices of Narryer Terrane and allochthonous Palaeoproterozoic volcanic arc and back arc rocks during the Capricorn Orogeny. This episode of crustal shortening resulted from the collision of the Yilgarn and Pilbara Cratons to form the West Australian Craton. The dates reflect cooling associated with subsequent erosion-induced rebound. The 2450 Ma biotite dates of the eastern area are similar to biotite dates found over most of the Yilgarn Craton and represent a background upon which the later dates have been superimposed. The origin of dates in the western area is unknown but may be related to an associated dolerite dyke swarm or to possible thrusting from the west. There is some evidence of minor later intrusion of felsic hypabyssal rock between 2000 and 2200 Ma and localised shearing in the Narryer area at about 1350 to 1400 Ma. One small area near Yalgoo with biotite Rb-Sr dates near 2200 Ma may be co genetic with the Muggamurra Swarm of dolerite

  1. Preferential rifting of continents - A source of displaced terranes

    Science.gov (United States)

    Vink, G. E.; Morgan, W. J.; Zhao, W.-L.

    1984-01-01

    Lithospheric rifting, while prevalent in the continents, rarely occurs in oceanic regions. To explain this preferential rifting of continents, the total strength of different lithospheres is compared by integrating the limits of lithospheric stress with depth. Comparisons of total strength indicate that continental lithosphere is weaker than oceanic lithosphere by about a factor of three. Also, a thickened crust can halve the total strength of normal continental lithosphere. Because the weakest area acts as a stress guide, any rifting close to an ocean-continent boundary would prefer a continental pathway. This results in the formation of small continental fragments or microplates that, once accreted back to a continent during subduction, are seen as displaced terranes. In addition, the large crustal thicknesses associated with suture zones would make such areas likely locations for future rifting episodes. This results in the tendency of new oceans to open along the suture where a former ocean had closed.

  2. Killing tanoak in northwestern California

    Science.gov (United States)

    D. F. Roy

    1956-01-01

    Residual tanoak (Lithocarpus densiflorus (Hook. & Arn.) Rehd.) trees and tanoak sprouts often are an important component of the vegetation which competes with conifer reproduction in northwestern California. Sometimes enough tanoak is present in Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) stands to dominate the...

  3. Some contrasting biostratigraphic links between the Baker and Olds Ferry Terranes, eastern Oregon

    Science.gov (United States)

    Nestell, Merlynd K.; Blome, Charles D.

    2016-01-01

    New stratigraphic and paleontologic data indicate that ophiolitic melange windows in the Olds Ferry terrane of eastern Oregon contain limestone blocks and chert that are somewhat different in age than those present in the adjacent Baker terrane melange. The melange windows in the Olds Ferry terrane occur as inliers in the flyschoid Early and Middle Jurassic age Weatherby Formation, which depositionally overlies the contact between the melange-rich Devonian to Upper Triassic rocks of the Baker terrane on the north, and Upper Triassic and Early Jurassic volcanic arc rocks of the Huntington Formation on the south. The Baker terrane and Huntington Formation represent fragments of a subduction complex and related volcanic island arc, whereas the Weatherby Formation consists of forearc basin sedimentary deposits. The tectonic blocks in the melange windows of the Weatherby Formation (in the Olds Ferry terrane) are dated by scarce biostratigraphic evidence as Upper Pennsylvanian to Lower Permian and Upper Triassic. In contrast, tectonic blocks of limestone in theBaker terrane yield mostly fusulinids and small foraminifers of Middle Pennsylvanian Moscovian age at one locality.Middle Permian (Guadalupian) Tethyan fusulinids and smaller foraminifers (neoschwagerinids and other Middle Permian genera) are present at a few other localities. Late Triassic conodonts and bryozoans are also present in a few of the Baker terrane tectonic blocks. These limestone blocks are generally embedded in Permian and Triassic radiolarian bearing chert or argillite. Based on conodont, radiolarian and fusulinid data, the age limits of the meange blocks in the Weatherby Formation range from Pennsylvanian to Late Triassic.

  4. An exotic terrane in the Sulu UHP region, China

    Science.gov (United States)

    Chu, W.; Zhang, R.; Tsujimori, T.; Liou, J. G.

    2004-12-01

    The Haiyangsuo region of about 15 km2 along the coast in the NE part of the Triassic Sulu UHP terrane occurs three major rock types: amphibolitized metagabbro, gneiss and granitic dikes. Three different gneisses were observed in the field: A) Light color felsic gneiss is the dominant country rock and contains Qtz, Pl, Ms and Bi. B) Dark color plagioclase-amphibole gneiss occurs as thin layers within country rock; C) Granulite facies rock occurs as discontinuous lens. The amphibolitized metagabbros intrude into the gneisses as massive bodies (several m to hundreds of m in size) and thin dikes. Both metamorphic intrusives and gneisses are cross-cut by granitic dikes. The amphibolitized metagabbro was divided into three types: coronal metagabbro, transitional rock and garnet amphibolite: 1) Coronal metagabbro preserves gabbroic texture and primary assemblage of Opx+Cpx+Pl+Amp+Ilm. Most pyroxene grains are partially rimmed by thin corona of Amp+Ab+Qtz. Garnet occurs as fine-grained coronas at interface between plagioclase, pyroxene or ilmenite. 2) Transitional rocks contain similar assemblage and texture but most orthopyroxenes were partially or totally replaced by Amp+Qtz; garnet increases in content and size. Some gabbroic textures are preserved, but calcic plagioclase was replaced by zoisite, albite and muscovite. 3) Garnet amphibolite occurs at the margins of intrusive bodies and boudins where only minor relict clinopyroxenes preserve. Garnet coronal chains are not clear any more. Granitic dikes show pronounced deformation with mylonitic texture and contain 40-50% quartz porphyroclasts. Zircon separates from 2 metagabbros, 4 gneisses and 1 granitic rock were dated by using Stanford SHRIMP-RG. Metagabbroic zircons are angular and fractured shapes. The upper-intercept ages of gneisses rang from 1730 to about 2400 Ma, indicating variable protoith age. The 2 garnet amphibolites have upper-intercept ages 1734±5Ma and 1735±21Ma respectively. They are much older than

  5. Cenozoic extensional tectonics of the Western Anatolia Extended Terrane, Turkey

    International Nuclear Information System (INIS)

    Cemen, I; Catlos, E J; Gogus, O; Diniz, E; Hancer, M

    2008-01-01

    The Western Anatolia Extended Terrane in Turkey is located on the eastern side of the Aegean Extended Terrane and contains one of the largest metamorphic core complexes in the world, the Menderes massif. It has experienced a series of continental collisions from the Late Cretaceous to the Eocene during the formation of the Izmir-Ankara-Erzincan suture zone. Based our field work and monazite ages, we suggest that the north-directed postcollisional Cenozoic extension in the region is the product of three consecutive stages, triggered by three different mechanisms. The first stage was initiated about 30 Ma ago, in the Oligocene by the Orogenic Collapse the thermally weakened continental crust along the north-dipping Southwest Anatolian shear zone. The shear zone was formed as an extensional simple-shear zone with listric geometry at depth and exhibits predominantly normal-slip along its southwestern end. But, it becomes a high-angle oblique-slip shear zone along its northeastern termination. Evidence for the presence of the shear zone includes (1) the dominant top to the north-northeast shear sense indicators throughout the Menderes massif, such as stretching lineations trending N10E to N30E; and (2) a series of Oligocene extensional basins located adjacent to the shear zone that contain only carbonate and ophiolitic rock fragments, but no high grade metamorphic rock fragments. During this stage, erosion and extensional unroofing brought high-grade metamorphic rocks of the Central Menderes massif to the surface by the early Miocene. The second stage of the extension was triggered by subduction roll-back and associated back-arc extension in the early Miocene and produced the north-dipping Alasehir and the south-dipping Bueyuek Menderes detachments of the central Menderes massif and the north-dipping Simav detachment of the northern Menderes massif. The detachments control the Miocene sedimentation in the Alasehir, Bueyuek Menderes, and Simav grabens, containing high

  6. Far-travelled permian chert of the North Fork terrane, Klamath mountains, California

    Science.gov (United States)

    Mankinen, E.A.; Irwin, W.P.; Blome, C.D.

    1996-01-01

    Permian chert in the North Fork terrane and correlative rocks of the Klamath Mountains province has a remanent magnetization that is prefolding and presumably primary. Paleomagnetic results indicate that the chert formed at a paleolatitude of 8.6?? ?? 2.5?? but in which hemisphere remains uncertain. This finding requires that these rocks have undergone at least 8.6?? ?? 4.4?? of northward transport relative to Permian North America since their deposition. Paleontological evidence suggests that the Permian limestone of the Eastern Klamath terrane originated thousands of kilometers distant from North America. The limestone of the North Fork terrane may have formed at a similar or even greater distance as suggested by its faunal affinity to the Eastern Klamath terrane and more westerly position. Available evidence indicates that convergence of the North Fork and composite Central Metamorphic-Eastern Klamath terranes occurred during Triassic or Early Jurassic time and that their joining together was a Middle Jurassic event. Primary and secondary magnetizations indicate that the new composite terrane containing these and other rocks of the Western Paleozoic and Triassic belt behaved as a single rigid block that has been latitudinally concordant with the North American craton since Middle Jurassic time.

  7. Cebollati group, Nico Perez terrane: Definition and age

    International Nuclear Information System (INIS)

    Gaucher, C; Chemale, F.; Bossi, J.; Castiglioni, E.; Castiglioni, E.

    2010-01-01

    The Cebollati Group (Nico Perez Terrane) is formally erected in this work to include a meta sedimentary succession informally known as L as Teta s Complex . It is shown that the stratigraphy of the unit can be reconstructed at a number of sections between Minas and Zapicìn, using sedimentary structures and stromatolites as geo petal indicators. The basement of the group is represented by metamorphic rocks and granitoids of the La China Complex, for which a new U-Pb zircon age of 3.029 ± 54 Ma is presented. The Cebollatií Group comprises, from base to top, three formations: the Arroyo Ma lo Formation (sandstones and petites), Cerro de Valuable Formation (dolostones, partly stromatolitic, and p elites) and the Cerro del Diamant e Formation (p elites, BIF, quartz-pebble conglomerates and sandstones). The mean thickness of the Cebollatií Group is ca. 2 km, being greatest in the south and diminishing to the north. Available ages for the unit suggested a Neoarchean depositional age of 2.75 Ga. However, in this work 12 Nd model ages are presented for sedimentary rocks of the Cebollatí Group, which are mostly younger than 2.75 Ga, the youngest being 1.64 Ga. These ages call into question the Neoarchean age accepted for the unit, suggesting a Meso proterozoic depositional age. The evidence supporting both views is discussed in view of the new data. The minimum age of the Cebollatí Group is 1.3 Ga on the basis of carbon isotope ratios of dolostones and deformational ages consistently around 1.25 Ga

  8. The Punta del Este Suspect Terrane: a possible counterpart in Eastern Uruguay of the Namaqua Complex and Gariep Belt in Western Africa

    International Nuclear Information System (INIS)

    Preciozzi, F.; Basei, M.; Peel, E.

    2005-01-01

    The geology of the southwestern extreme of the African continent is characterised by a series of mobile belts that delimit the western margin of the block constituted by the Kalahari-Kapvaal cratons. In this context, Panafrican belts predominate, represented in the north-northwestern portion by the Damara, in the western region by the Gariep and, in the southern region by the Saldania. These belts, of Neoproterozoic-Eopaleozoic ages predominantly expose sedimentary covers metamorphosed in the greenschist facies. In the northwestern portion of South Africa and south of Namibia, of major interest for the correlation intended in this work. The basement of the Panafrican cover, in this case the Gariep Group, is largely constituted by medium- to high-grade terranes generated during the Kibarian event (1.2-1.1Ga) responsible for the formation of igneous and metamorphic rocks and attributed to the Metamorphic Namaqua-Natal Complex (Frimmel, 1995). This Complex presents low-pressure granulite facies conditions (Clifford et al., 1981) with polymetamorphic evolution, where old nuclei of Paleoproterozoic age (1800-2000Ma) occur within the terranes generated during the Kibarian orogeny. U-Pb studies in zircons by SHRIMP (Robb et al., 1998) confirmed for Namaqua two rock-generating events with pulses between 1220-1170 Ma (Kibarian) and 1060-1030Ma (Namaqua); with the latter the third regional deformation and important magmatism phases would be associated. In this period granulitic metamorphism and intrusion of granitoids 2 occurred and are presently represented by the Nababeep and Modderfontein gneisses that are cut by the Concordia and Rietberg granitoids. The Panafrican superposition is registered predominantly along the coastal region. The Gariep Group occurs along the coastal region tectonically covering the terranes associated with the Namaqua Metamorphic Complex. It is characterised by a group constituted mainly by rocks of very low to low metamorphic grade distributed in

  9. The Khida terrane - Geology of Paleoproterozoic rocks in the Muhayil area, eastern Arabian Shield, Saudi Arabia

    Science.gov (United States)

    Stoeser, D.B.; Whitehouse, M.J.; Stacey, J.S.

    2001-01-01

    The bulk of the Arabian Shield of Saudi Arabia is underlain by Neoproterozoic terranes of oceanic affinity that were accreted during Pan-African time (about 680- 640Ma). Geologicalmappingandisotopicinvestigations during the 1980’s,however, provided the first evidence for Paleoproterozoic continental crust within the east- central part of the shield in Saudi Arabia. These studies delineated an older basement domain, herein referred to as the Khida terrane (Fig. l), which is defined as that part of the southern Afif composite terrane underlain by Paleoproterozoicto Archean continental crust (Stoeser and Stacey, 1988). The isotopic and geochronologic work to support our current studies within the Khida terrane are discussed in a companion abstract (Whitehouse et al., this volume). The regional geology and geochronology of the region has been summarized in detail by Johnson (1996). The current study is based on the continued use of samples previously collected in the Khida area by the authors and others as well as new field work conducted by us in 1999. This work further defines the occurrence of late Paleoproterozoic rocks at Jabal Muhayil, which is located at the eastern margin of the exposed terrane (Fig. 1). Our isotopic work is at an early stage and this abstract partly relates geologic problems that remain to be resolved. 

  10. Tectonic evolution of the Caribbean and northwestern South America: The case for accretion of two Late Cretaceous oceanic plateaus

    Science.gov (United States)

    Kerr, Andrew C.; Tarney, John

    2005-04-01

    It is widely accepted that the thickened oceanic crust of the Caribbean plate, its basaltic accreted margins, and accreted mafic terranes in northwestern South America represent the remnants of a single ca. 90 Ma oceanic plateau. We review geologic, geochemical, and paleomagnetic evidence that suggests that the Caribbean-Colombian oceanic plateau in fact represents the remnants of two different oceanic plateaus, both dated as ca. 90 Ma. The first of these plateaus, the Caribbean Plateau, formed ca. 90 Ma in the vicinity of the present-day Galapagos hotspot. Northeastward movement of the Farallon plate meant that this plateau collided with the proto Caribbean arc and northwestern South America Gorgona Plateau, formed at 26° 30°S, possibly at the site of the present-day Sala y Gomez hotspot. Over the next ˜45 m.y., this plateau was carried progressively northeastward on the Farallon plate and collided in the middle Eocene with the proto Andean subduction zone in northwestern South America. The recognition of a second ca. 90 Ma Pacific oceanic plateau strengthens the link between plateau formation and global oceanic anoxic events.

  11. The Athabasca Granulite Terrane and Evidence for Dynamic Behavior of Lower Continental Crust

    Science.gov (United States)

    Dumond, Gregory; Williams, Michael L.; Regan, Sean P.

    2018-05-01

    Deeply exhumed granulite terranes have long been considered nonrepresentative of lower continental crust largely because their bulk compositions do not match the lower crustal xenolith record. A paradigm shift in our understanding of deep crust has since occurred with new evidence for a more felsic and compositionally heterogeneous lower crust than previously recognized. The >20,000-km2 Athabasca granulite terrane locally provides a >700-Myr-old window into this type of lower crust, prior to being exhumed and uplifted to the surface between 1.9 and 1.7 Ga. We review over 20 years of research on this terrane with an emphasis on what these findings may tell us about the origin and behavior of lower continental crust, in general, in addition to placing constraints on the tectonic evolution of the western Canadian Shield between 2.6 and 1.7 Ga. The results reveal a dynamic lower continental crust that evolved compositionally and rheologically with time.

  12. Relationships between the Brook Street Terrane and Median Tectonic Zone (Median Batholith) : evidence from Jurassic conglomerates

    International Nuclear Information System (INIS)

    Tulloch, A.J.; Kimbrough, D.L.; Landis, C.A.; Mortimer, N.; Johnston, M.R.

    1999-01-01

    U-Pb zircon ages of 237-180 Ma and c. 280 Ma of seven granitoid clasts from the Rainy River Conglomerate which lies within the eastern Median Tectonic Zone (Median Batholith) in Nelson, and the Barretts Formation of the Brook Street Terrane in Southland, constrain the depositional ages of both units to be no older than c. 180-200 Ma (Early Jurassic). The minimum age of the Rainy River Conglomerate is constrained by the 147 +2 -1 Ma (Latest Jurassic) emplacement age of the One Mile Gabbronorite (new name: previously western Buller Diorite). The ages and chemistry of five of the granitoid clasts are broadly compatible with derivation from rocks that are now represented by Triassic plutons of the Median Tectonic Zone (Median Batholith), although ages as young as 180 Ma are slightly outside the range of the latter as currently exposed in New Zealand. The age (273-290 Ma, 237 +/- 3 Ma) and chemistry of the other two clasts (one each from Rainy River Conglomerate and Barretts Formation) suggest derivation from the Brook Street Terrane. Similarity in stratigraphic age, depositional characteristics, granitoid clast ages and composition between Rainy River Conglomerate and Barretts Formation suggests that they are broadly correlative and collectively overlapped a combined Brook Street Terrane - Median Batholith (MTZ) before the Late Jurassic (147 +2 -1 Ma). Sedimentary overlap may also have continued across to Middle Jurassic conglomeratic strata in the Murihiku Terrane to the east of the Brook Street Terrane. A U-Pb zircon age of 261 +/- 2 Ma is reported for Pourakino Trondhjemite of the Brook Street Terrane. (author). 56 refs., 10 figs., 4 tabs

  13. Chronologic constraints on the tectonic evolution of the Wilson Lake terrane of the Grenville Province, Canada

    DEFF Research Database (Denmark)

    Reno II, Barry Len; Korhonen, F.J.; Stout, J.H.

    the Grenville Orogen in North America. Many of these terranes record evidence of two orogenies: the Labradorian Orogeny at ca. 1710-1600 Ma, and the Grenville Orogeny at ca. 1080-980 Ma. The rocks in the Wilson Lake terrane are interpreted to have been subjected to peak pressures of ~0.95 GPa......) monazite exhibits distinct core and rim zoning in yttrium X-ray compositional maps, and occurs predominately in the melanosome of the rocks, and 2) a population of smaller (up to ~50 µm) unzoned monazite rarely occurs in quartz-rich layers of the rocks. In a majority of the melanosome-hosted monazite, (U...

  14. The Paleozoic-Mesozoic recycling of the Rakaia Terrane, South Island, New Zealand : sandstone clast and sandstone petrology, geochemistry, and geochronology

    International Nuclear Information System (INIS)

    Wandres, A.M.; Bradshaw, J.D.; Ireland, T.

    2005-01-01

    The Torlesse terranes - part of the New Zealand Eastern Province - are accretionary complexes that comprise an enormous volume of quartzofeldspathic sandstones and mudstones with subsidiary conglomerates plus minor oceanic assemblages. Two terranes are recognised in the South Island - the Permian to Late Triassic Rakaia Terrane and the Late Jurassic to Early Cretaceous Pahau Terrane. Sandstone clasts from two Rakaia Terrane and two Pahau Terrane conglomerates were collected. We present the first combined detailed information on petrography and geochemistry of Torlesse conglomerate sandstone clasts and use our own and published U-Pb SHRIMP detrital zircon age data to demonstrate the recycling of the Rakaia Terrane into Rakaia strata itself and into Pahau Terrane strata. Sandstone clast major and trace element chemical data largely support petrographic observations derived from thin-section analysis. The similarities of petrographic and geochemical data between sandstone clasts from the Rakaia Terrane and Rakaia sandstones suggest that clasts in the Permian Te Moana and Late Triassic Lake Hill Conglomerates were derived by autocannibalistic reworking of older, consolidated, Rakaia sediments. Data from sandstone clasts from the Pahau Terrane suggest that uplift of the Rakaia Terrane continued into the Cretaceous. These Pahau Terrane clasts indicate that at the time of the Pahau sedimentation Permian to early Late Triassic Rakaia rocks were exposed and recycled into the Pahau Basin. (author). 57 refs., 8 figs., 3 tables

  15. A tectonic reconstruction of accreted terranes along the paleo-Pacific margin of Gondwana

    Science.gov (United States)

    Bammel, Brandon

    The southern oceanic margin of Gondwana was nearly 40,000 km long or 24,854.8 miles. The southern margin was the result of the Terra Australis orogen. Spanning 18,000 km or 11,184.7 miles and is proposed as one of the largest and longest lived orogens in Earth history. The paleo-Pacific margin of Gondwana consisted of segments of the Australian-Antarctic craton, southern South America (modern Argentina and Chile), southern South Africa, Marie Byrdland, New Zealand and its adjacent continental shelf, the Ellsworth Mountains, and the Transantarctic Mountains. The process of terrane accretion has played a substantial part in the assembly of the continents as they look today. The paleo-Pacific margin of Gondwana was an active region of terrane accretion from the Neoproterozoic to the Late Mesozoic. This research study examines the accretion of terranes across the paleo-Pacific Gondwana margin to provide a comprehensive reconstruction. A paleogeographic basemap was created using PALEOMAP Project maps and the geology data was provided by the School of Geoscience from the University of Witwatersrand of South Africa. Location and data analyzed for terranes were collected building a PDF library of journal articles across numerous geological publications.

  16. Basic hypabissal, gondwanic magmatism: a new contribution for tecto no-stratigraphic terranes recognition in Uruguay

    International Nuclear Information System (INIS)

    Bossi, J.

    2006-01-01

    The possibility of having sufficient structural, geochronologic and geochemical data about the dykes and sills of Cuaro formation and the Corral de Piedra dyke swarm allowed to suggest the nature of the Mantle source and the injection process of each filonian set. Three units injected in the Gondwana continent were recognized: not outcropping Cuaro formation, at Piedra Alta Terrane; outcropping Cuaro Fm. in the Nico Perez Terrane, and the Corral de Piedra dyke swarm in the Cuchilla Dionisio terrane It was found different behavior in several important parameters in each one of them: mantelic source , melting percentage and crustal contamination. It may be concluded that Mantle nature and crust thickness and composition are different in each block, what supports. the idea that continental socle was constructed by amalgamation of different units of allocton provenence. When heat loss became difficult by the mega-continent consolidation, each fragment acted of different way. This represents a very strong argument favoring terrane Cuchilla Dionisio alloctony leaned to 525 Ma as regional geological mapping indicated

  17. Late Ordovician palaeogeography and the positions of the Kazakh terranes through analysis of their brachiopod faunas

    Science.gov (United States)

    Popov, Leonid E.; Cocks, Robin M.

    2017-09-01

    Detailed biogeographical and biofacies analyses of the Late Ordovician brachiopod faunas with 160 genera, grouped into 94 faunas from individual lithotectonic units within the Kazakh Orogen strongly support an archipelago model for that time in that area. The Kazakh island arcs and microcontinents within several separate clusters were located in the tropics on both sides of the Equator. Key units, from which the Late Ordovician faunas are now well known, include the Boshchekul, Chingiz-Tarbagatai, and Chu-Ili terranes. The development of brachiopod biogeography within the nearly ten million year time span of the Late Ordovician from about 458 to 443 Ma (Sandbian, Katian, and Hirnantian), is supported by much new data, including our revised identifications from the Kazakh Orogen and elsewhere. The Kazakh archipelago was west of the Australasian segment of the Gondwana Supercontinent, and relatively near the Tarim, South China and North China continents, apart from the Atashu-Zhamshi Microcontinent, which probably occupied a relatively isolated position on the south-western margin of the archipelago. Distinct faunal signatures indicate that the Kazakh terranes were far away from Baltica and Siberia throughout the Ordovician. Although some earlier terranes had joined each other before the Middle Ordovician, the amalgamation of Kazakh terranes into the single continent of Kazakhstania by the end of the Ordovician is very unlikely. The Late Ordovician brachiopods from the other continents are also compared with the Kazakh faunas and global provincialisation statistically determined.

  18. The ophiolitic North Fork terrane in the Salmon River region, central Klamath Mountains, California

    Science.gov (United States)

    Ando, C.J.; Irwin, W.P.; Jones, D.L.; Saleeby, J.B.

    1983-01-01

    The North Fork terrane is an assemblage of ophiolitic and other oceanic volcanic and sedimentary rocks that has been internally imbricated and folded. The ophiolitic rocks form a north-trending belt through the central part of the region and consist of a disrupted sequence of homogeneous gabbro, diabase, massive to pillowed basalt, and interleaved tectonitic harzburgite. U-Pb zircon age data on a plagiogranite pod from the gabbroic unit indicate that at least this part of the igneous sequence is late Paleozoic in age.The ophiolitic belt is flanked on either side by mafic volcanic and volcaniclastic rocks, limestone, bedded chert, and argillite. Most of the chert is Triassic, including much of Late Triassic age, but chert with uncertain stratigraphic relations at one locality is Permian. The strata flanking the east side of the ophiolitic belt face eastward, and depositional contacts between units are for the most part preserved. The strata on the west side of the ophiolitic belt are more highly disrupted than those on the east side, contain chert-argillite melange, and have unproven stratigraphic relation to either the ophiolitic rocks or the eastern strata.Rocks of the North Fork terrane do not show widespread evidence of penetrative deformation at elevated temperatures, except an early tectonitic fabric in the harzburgite. Slip-fiber foliation in serpentinite, phacoidal foliation in chert and mafic rocks, scaly foliation in argillite, and mesoscopic folds in bedded chert are consistent with an interpretation of large-scale anti-formal folding of the terrane about a north-south hinge found along the ophiolitic belt, but other structural interpretations are tenable. The age of folding of North Fork rocks is constrained by the involvement of Triassic and younger cherts and crosscutting Late Jurassic plutons. Deformation in the North Fork terrane must have spanned a short period of time because the terrane is bounded structurally above and below by Middle or Late

  19. Lithospheric electrical structure of the middle Lhasa terrane in the south Tibetan plateau

    Science.gov (United States)

    Liang, Hongda; Jin, Sheng; Wei, Wenbo; Gao, Rui; Ye, Gaofeng; Zhang, Letian; Yin, Yaotian; Lu, Zhanwu

    2018-04-01

    The Lhasa terrane in southern Tibetan plateau is a huge tectono-magmatic belt and an important metallogenic belt. Its formation evolution process and mineralization are affected by the subduction of oceanic plate and subsequent continental collision. However, the evolution of Lhasa terrane has been a subject of much debate for a long time. The Lithospheric structure records the deep processes of the subduction of oceanic plate and continental collision. The magnetotelluric (MT) method can probe the sub-surface electrical conductivity, newly dense broadband and long period magnetotelluric data were collected along a south-north trending profile that across the Lhasa terrane at 88°-89°E. Dimensionality analyses demonstrated that the MT data can be interpreted using two-dimensional approaches, and the regional strike direction was determined as N110°E.Based on data analysis results, a two-dimensional (2-D) resistivity model of crust and upper mantle was derived from inversion of the transverse electric mode, transverse magnetic mode and vertical magnetic field data. Inversion model shows a large north-dipping resistor that extended from the upper crust to upper mantle beneath the Himalaya and the south of Lhasa Terrane, which may represent the subducting Indian continental lithosphere. The 31°N may be an important boundary in the Lhasa Terrane, the south performs a prominent high-conductivity anomaly from the lower crust to upper mantle which indicates the existence of asthenosphere upwelling, while the north performs a higher resistivity and may have a reworking ancient basement. The formation of the ore deposits in the study area may be related to the upwelling of the mantle material triggered by slab tearing and/or breaking off of the Indian lithosphere, and the mantle material input also contributed the total thickness of the present-day Tibetan crust. The results provide helpful constrains to understand the mechanism of the continent-continent collision and

  20. Evidence From Detrital Zircon U-Pb Analysis for Suturing of Pre-Mississippian Terranes in Arctic Alaska

    Science.gov (United States)

    Moore, T. E.; Potter, C. J.; O'Sullivan, P. B.; Aleinikoff, J. N.

    2007-12-01

    900 Ma and 1200-1450 Ma that are not seen in the Neroukpuk sample, as well as a cluster of ages at 320-390 Ma. This sample indicates that the Neroukpuk is not the only source of zircons for Mississippian strata in the northeast Brooks Range. The samples from the northeastern Brooks Range contain zircon distributions similar to those reported from autochthonous North American strata in east-central Alaska and are strikingly different from those in western and southern parts of the Arctic Alaska terrane. Peaks at ~1.8 Ga are subdued or missing in the latter samples and 1.5-1.6 Ga grains, a magmatic gap in Laurentia, are present in the Lisburne Peninsula and North Slope samples. In view of these data, field and seismic evidence for significant Devonian deformation in northern Alaska, and likely plate configurations for that time, northern Alaska probably records early to mid-Paleozoic closing of the Iapatus Ocean and collisional suturing of non-Laurentian continental blocks with northwestern North America. This suggests that Devonian deformation in Arctic Alaska represents an important, northern element of the Caledonian deformational system that probably once linked up with Caledonian structures in the Canadian Arctic Islands and adjacent continental margin region.

  1. Origin and tectonic evolution of early Paleozoic arc terranes abutting the northern margin of North China Craton

    Science.gov (United States)

    Zhou, Hao; Pei, Fu-Ping; Zhang, Ying; Zhou, Zhong-Biao; Xu, Wen-Liang; Wang, Zhi-Wei; Cao, Hua-Hua; Yang, Chuan

    2017-12-01

    The origin and tectonic evolution of the early Paleozoic arc terranes abutting the northern margin of the North China Craton (NCC) are widely debated. This paper presents detrital zircon U-Pb and Hf isotopic data of early Paleozoic strata in the Zhangjiatun arc terrane of central Jilin Province, northeast (NE) China, and compares them with the Bainaimiao and Jiangyu arc terranes abutting the northern margin of the NCC. Detrital zircons from early Paleozoic strata in three arc terranes exhibit comparable age groupings of 539-430, 1250-577, and 2800-1600 Ma. The Paleoproterozoic to Neoarchean ages and Hf isotopic composition of the detrital zircons imply the existence of the Precambrian fragments beneath the arc terranes. Given the evidences from geology, igneous rocks, and detrital zircons, we proposed that the early Paleozoic arc terranes abutting the northern margin of the NCC are a united arc terrane including the exotic Precambrian fragments, and these fragments shared a common evolutionary history from Neoproterozoic to early-middle Paleozoic.

  2. Crustal structure of norther Oaxaca terrane; The Oaxaca and caltepec faults, and the Tehuacan Valley. A gravity study.

    Science.gov (United States)

    Campos-Enriquez, J. O.; Alatorre-Zamora, M. A.; Ramón, V. M.; Belmonte, S.

    2014-12-01

    Northern Oaxaca terrane, southern Mexico, is bound by the Caltepec and Oaxaca faults to the west and east, respectively. These faults juxtapose the Oaxaca terrane against the Mixteca and Juarez terranes, respectively. The Oaxaca Fault also forms the eastern boundary of the Cenozoic Tehuacan depression. Several gravity profiles across these faults and the Oaxaca terrane (including the Tehuacan Valley) enables us to establish the upper crustal structure of this region. Accordingly, the Oaxaca terrane is downward displaced to the east in two steps. First the Santa Lucia Fault puts into contact the granulitic basamental rocks with Phanerozoic volcanic and sedimentary rocks. Finally, the Gavilan Fault puts into contact the Oaxaca terrane basement (Oaxaca Complex) into contact with the volcano-sedimentary infill of the valley. This gravity study reveals that the Oaxaca Fault system gives rise to a series of east tilted basamental blocks (Oaxaca Complex?). A structural high at the western Tehuacan depression accomadates the east dipping faults (Santa Lucia and Gavilan faults) and the west dipping faults of the Oaxaca Fault System. To the west of this high structural we have the depper depocenters. The Oaxaca Complex, the Caltepec and Santa Lucia faults continue northwestwards beneath Phanerozoic rocks. The faults are regional tectonic structures. They seem to continue northwards below the Trans-Mexican Volcanic Belt. A major E-W to NE-SW discontinuity on the Oaxaca terrane is inferred to exist between profiles 1 and 2. The Tehuacan Valley posses a large groundwater potential.

  3. U-Pb geochronologic constraints on Paleoproterozoic orogenesis in the northwestern Makkovik Province, Labrador, Canada

    International Nuclear Information System (INIS)

    Ketchum, J.W.F.; Dunning, G.R.; Dunning, G.R.

    1997-01-01

    A 45 km wide, shear-zone-bounded segment of the northwestern Makkovik Province, Labrador, is underlain by Archean gneisses derived from the adjacent Nain craton. This lithotectonic block (Kaipokok domain) was reworked at high metamorphic grade, overthrust by supracrustal sequences (Lower Aillik and Moran Lake groups), and intruded by granitoid plutons during the Paleoproterozoic. Initial amphibolite-facies reworking of the Kaipokok domain at 1896 ± 6 Ma is indicated by U-Pb ages of metamorphic zircon from a foliated Kikkertavak metadiabase dyke. This is one of the oldest Paleoproterozoic tectonic events dated thus far in northeast Laurentia and may be linked with ca. 1890 Ma plutonism documented elsewhere in the Kaipokok domain. Intrusion of granitoid plutons at 1882 -6 +10 , 1877 ± 5, and 1871 -3 +4 Ma in the Kaipokok Bay area postdates early thick- and thin-skinned thrusting (possibly east to northeast directed) that involved Lower Aillik Group strata. U-Pb titanite ages of 1866 - 1847 Ma in part record a metamorphic event that followed this plutonic-tectonic activity. These early events are temporally and kinematically difficult to reconcile with accretion of juvenile Makkovikian terranes in the southeast and may instead be related to early stages of the ca. 1.91 - 1.72 Ga Torngat orogeny along the western margin of the Nain craton. In contrast, high-grade metamorphism, dextral shearing, and northwestward thrusting between 1841 and 1784 Ma, including crystallization of an Iggiuk granitic vein at 1811 ± 8 Ma, are in accord with accretion of Makkovikian terranes in a dextral transpressional regime (Makkovikian orogeny sensu stricto). Coeval sinistral transpression in the Torngat orogen suggests that both orogenic belts accommodated relative northward tectonic escape of the Nain craton during this interval. (author)

  4. Structure and tectonics of the northwestern United States from EarthScope USArray magnetotelluric data

    Science.gov (United States)

    Bedrosian, Paul A.; Feucht, Daniel W.

    2014-01-01

    The magnetotelluric component of the EarthScope USArray program has covered over 35% of the continental United States. Resistivity tomography models derived from these data image lithospheric structure and provide constraints on the distribution of fluids and melt within the lithosphere. We present a three-dimensional resistivity model of the northwestern United States which provides new insight into the tectonic assembly of western North America from the Archean to present. Comparison with seismic tomography models reveals regions of correlated and anti-correlated resistivity and velocity that help identify thermal and compositional variations within the lithosphere. Recent (Neogene) tectonic features reflected in the model include the subducting Juan de Fuca–Gorda plate which can be traced beneath the forearc to more than 100 km depth, high lithospheric conductivity along the Snake River Plain, and pronounced lower-crustal and upper-mantle conductivity beneath the Basin and Range. The latter is abruptly terminated to the northwest by the Klamath–Blue Mountains Lineament, which we interpret as an important structure during and since the Mesozoic assembly of the region. This boundary is interpreted to separate hot extended lithosphere from colder, less extended lithosphere. The western edge of Proterozoic North America, as indicated by the Cretaceous initial 87Sr/86Sr = 0.706 contour, is clearly reflected in the resistivity model. We further image an Archean crustal block (“Pend Oreille block”) straddling the Washington/Idaho border, which we speculate separated from the Archean Medicine Hat block in the Proterozoic. Finally, in the modern Cascades forearc, the geometry and internal structure of the Eocene Siletz terrane is reflected in the resistivity model. The apparent eastern edge of the Siletz terrane under the Cascades arc suggests that pre-Tertiary rocks fill the Washington and Oregon back-arc.

  5. Paleozoic–early Mesozoic gold deposits of the Xinjiang Autonomous Region, northwestern China

    Science.gov (United States)

    Rui, Zongyao; Goldfarb, Richard J.; Qiu, Yumin; Zhou, T.; Chen, R.; Pirajno, Franco; Yun, Grace

    2002-01-01

    The late Paleozoic–early Mesozoic tectonic evolution of Xinjiang Autonomous Region, northwestern China provided a favorable geological setting for the formation of lode gold deposits along the sutures between a number of the major Eastern Asia cratonic blocks. These sutures are now represented by the Altay Shan, Tian Shan, and Kunlun Shan ranges, with the former two separated by the Junggar basin and the latter two by the immense Tarim basin. In northernmost Xinjiang, final growth of the Altaid orogen, southward from the Angara craton, is now recorded in the remote mid- to late Paleozoic Altay Shan. Accreted Early to Middle Devonian oceanic rock sequences contain typically small, precious-metal bearing Fe–Cu–Zn VMS deposits (e.g. Ashele). Orogenic gold deposits are widespread along the major Irtysh (e.g. Duyolanasayi, Saidi, Taerde, Kabenbulake, Akexike, Shaerbulake) and Tuergen–Hongshanzui (e.g. Hongshanzui) fault systems, as well as in structurally displaced terrane slivers of the western Junggar (e.g. Hatu) and eastern Junggar areas. Geological and geochronological constraints indicate a generally Late Carboniferous to Early Permian episode of gold deposition, which was coeval with the final stages of Altaid magmatism and large-scale, right-lateral translation along older terrane-bounding faults. The Tian Shan, an exceptionally gold-rich mountain range to the west in the Central Asian republics, is only beginning to be recognized for its gold potential in Xinjiang. In this easternmost part to the range, northerly- and southerly-directed subduction/accretion of early to mid-Paleozoic and mid- to late Paleozoic oceanic terranes, respectively, to the Precambrian Yili block (central Tian Shan) was associated with 400 to 250 Ma arc magmatism and Carboniferous through Early Permian gold-forming hydrothermal events. The more significant resulting deposits in the terranes of the southern Tian Shan include the Sawayaerdun orogenic deposit along the Kyrgyzstan

  6. Unusual central Nevada geologic terranes produced by Late Devonian Antler orogeny and Alamo impact

    Science.gov (United States)

    Poole, Forrest G.; Sandberg, Charles

    2015-01-01

    This Special Paper is the product of nearly 25 years of geologic investigations. It is an exposition of two small areas, both less than 25 km east of the Mississippian Roberts Mountains allochthon, but each displaying a different, unique geologic terrane, previously undocumented in Nevada and perhaps in North America. One area, the Bisoni-McKay, at the south end of the Fish Creek Range, displays an olistostrome, shed eastward during the late Late Devonian (early Famennian) from a migrating Antler orogenic forebulge. The other, the Warm Springs–Milk Spring, at the south end of the Hot Creek Range, displays a deeper marine terrane affected by the early Late Devonian (middle Frasnian) Alamo impact.

  7. Thermochronology of the Sulu ultrahigh-pressure metamorphic terrane: Implications for continental collision and lithospheric thinning

    Science.gov (United States)

    Liu, Li-Ping; Li, Zheng-Xiang; Danišík, Martin; Li, Sanzhong; Evans, Noreen; Jourdan, Fred; Tao, Ni

    2017-08-01

    The thermal history of the Dabie-Sulu orogenic belt provides important constraints on the collision process between the South China and North China blocks during the Mesozoic, and possible lithospheric thinning event(s) in the eastern North China Block. This study reports on the thermal evolution of the Sulu ultrahigh-pressure metamorphic (UHP) terrane using zircon U-Pb geochronology and multiple thermochronology methods such as mica and hornblende 40Ar/39Ar, zircon and apatite fission track, and zircon and apatite (U-Th)/He dating. 40Ar/39Ar and zircon (U-Th)/He data show that the UHP terrane experienced accelerated cooling during 180-160 Ma. This cooling event could be interpreted to have resulted from extensional unroofing of an earlier southward thrusting nappe, or, more likely, an episode of northward thrusting of the UHP rocks as a hanging wall. A subsequent episode of exhumation took place between ca. 125 Ma and 90 Ma as recorded by zircon (U-Th)/He data. This event was more pronounced in the northwest section of the UHP terrane, whereas in the southeast section, the zircon (U-Th)/He system retained Jurassic cooling ages of ca. 180-160 Ma. The mid-Cretaceous episode of exhumation is interpreted to have resulted from crustal extension due to the removal of thickened, enriched mantle. A younger episode of exhumation was recorded by apatite fission track and apatite (U-Th)/He ages at ca. 65-40 Ma. Both latter events were linked to episodic thinning of lithosphere along the Sulu UHP terrane in an extensional environment, likely caused by the roll-back of the Western Pacific subduction system.

  8. Zircon U-Pb ages of Guyana greenstone-gneiss terrane

    Energy Technology Data Exchange (ETDEWEB)

    Gibbs, A.K. (Cornell Univ., Ithaca, NY (USA)); Olszewski, W.J. Jr. (New Hampshire Univ., Durham (USA))

    1982-04-01

    Isotopic U-Pb studies of zircons collected from weathered metagreywackes of the Barama-Mazaruni Supergroup of northern Guyana, South America, demonstrate an age of origin of ca. 2250 Ma. This is the best estimate for the age of the associated metavolcanic rocks. Zircons from weathered gneiss of the Bartica complex, adjacent to the volcanic-sedimentary belts, yield a similar age. The contiguous greenstone-gneiss terrane of eastern Venezuela is also of similar age and comparable greenstone-gneiss terranes of eastern Suriname and French Guiana are probably also of this age. Continental crust formation of a style closely comparable to that of the Canadian Archean occurred on a very widespread scale in the Lower Proterozoic of the Guiana shield. The lead losses from the weathered zircons are comparable to those from zircons from fresh rock from the adjacent terrane of Venezuela, and the advantages of field concentration from numerous saprolite exposures warrant use of such material in future geochronological studies of the region.

  9. Detrital zircon ages in Buller and Takaka terranes, New Zealand : constraints on early Zealandia history

    International Nuclear Information System (INIS)

    Adams, C.J.; Mortimer, N.; Campbell, H.J.; Griffin, W.L.

    2015-01-01

    Detrital zircon ages are presented for 34 early Palaeozoic sandstones from Buller and Takaka terranes, New Zealand, and formerly adjacent parts of Australia-Antarctica. The Buller-Takaka datasets always have two major groups: Ordovician-late Neoproterozoic, 444-700 Ma (but mainly 540-700 Ma), termed 'Gondwana Assembly' (GA), and early Neoproterozoic-Mesoproterozoic, 700-1600 Ma (but mainly 900-1200 Ma), termed 'Rodinia Assembly' (RA). In both terranes, significant age components within these groups are strikingly similar and also have RA/GA ratios, 0.6-1.8. The Cambrian volcanic arc of the Takaka Terrane has contributed little to the zircon patterns. Proportions of Late Cambrian-Early Ordovician zircons, characteristic of granitoid sources in the Ross-Delamerian Orogen are low. The zircons are predominantly reworked with contemporary zircons only evident in a few Buller datasets. The zircon patterns suggest that two major sources (late Mesoproterozoic and late Neoproterozoic), enduring over 120 Ma, were widely distributed and it is postulated they form Precambrian basement beneath southern Zealandia. (author).

  10. Sedimentary records on the subduction-accretion history of the Russian Altai, northwestern Central Asian Orogenic Belt

    Science.gov (United States)

    Chen, Ming; Sun, Min

    2017-04-01

    The Russian Altai, comprising the northern segment of the Altai-Mongolian terrane (AM) in the south, the Gorny Altai terrane (GA) in the north and the intervening Charysh-Terekta-Ulagan-Sayan suture zone, is a key area of the northwestern Central Asian Orogenic Belt (CAOB). A combined geochemical and detrital zircon study was conducted on the (meta-)sedimentary sequences from the Russian Altai to reveal the tectono-magmatic history of these two terranes and their amalgamation history, which in turn place constraints on the accretionary orogenesis and crustal growth in the CAOB. The Cambrian-Ordovician meta-sedimentary rocks from the northern AM are dominated by immature sediments possibly sourced from intermediate-felsic igneous rocks. Geochemical data show that the sediments were likely deposited in a continental arc-related setting. Zircons separated from these rocks are mainly 566-475 Ma and 1015-600 Ma old, comparable to the magmatic records of the Tuva-Mongolian terrane and surrounding island arcs in the western Mongolia. The similar source nature, provenance and depositional setting of these rocks to the counterparts from the Chinese Altai (i.e., the southern AM) imply that the whole AM possibly represents a coherent accretionary prism of the western Mongolia in the early Paleozoic rather than a Precambrian continental block with passive marginal deposition as previously thought. In contrast, the Cambrian to Silurian (meta-)sedimentary rocks from the GA are characterized by a unitary zircon population with ages of 640-470 Ma, which were potentially sourced from the Kuznetsk-Altai intra-oceanic island arc in the east of this terrane. The low abundance of 640-540 Ma zircons (5%) may attest that this arc was under a primitive stage in the late Neoproterozoic, when mafic igneous rocks dominated. However, the voluminous 530-470 Ma zircons (95%) suggest that this arc possibly evolved toward a mature one in the Cambrian to early Ordovician with increasing amount of

  11. Precambrian terranes of African affinities in the southeastern part of Brazil and Uruguay

    International Nuclear Information System (INIS)

    Basei, M.A.S; Junior, Siga; Harara, O.M; Preciozzi, F; Sato, K; Kaufuss, G

    2001-01-01

    The interest in correlating terranes at opposite margins of the South Atlantic Ocean reflects a natural curiosity of both researchers who work in the eastern South-America and who study southwestern Africa. On a large scale scenario the geology of this region is characterized by a central portion composed of Neo proterozoic-Cambrian belts (Dom Feliciano, Kaoko, Damara, Gariep, Saldania) having on each side old gneissic-migmatitic terrains on both continents (Luis Alves, Rio de La Plata, Kalahari and Congo). In South America the Neoproterozoic Dom Feliciano Belt (DFB) predominates in the eastern part of the region and is internally organized according to three different crustal segments characterized, from southeast to northwest, by a Granite belt (deformed I-type medium to high calc-alkaline granites and alkaline granitoid rocks; a Schist belt (volcano-sedimentary rocks metamorphosed from greenschist to amphibolite facies and intrusive granitoids), and a Foreland basin (anchimetamorphic sedimentary and volcanic rocks), the latter situated between the Schist belt and the Archean-Paleoproterozoic foreland. Despite discontinuously covered by younger sediments, the NS continuity of these three crustal segments is suggested by similar lithotypes, structural characteristics, ages and isotopic signature, as well as by the gravimetric data. The Major Gercino, Cordilheira, and Sierra Ballena shear zones are part of the major NE-SW lineaments that affect all southern Brazilian and Uruguayan Precambrian terrains. They separate the Dom Feliciano Schist Belt (supracrustal rocks of the Brusque-Porongos and Lavalleja groups), to the West, from the granitoids of the Granite belt, to the East. The shear zones are characterized by a regional NE trend and a resultant oblique direction of movement where ductile-brittle structures predominate. It is here postulated, as discussed later on, that this lineament separates terranes that are geologically, geo chronologically and isotopically

  12. Isotopic provenance analysis and terrane tectonics: a warning about sediment transport distances

    International Nuclear Information System (INIS)

    Bassett, K.N.

    1999-01-01

    Full text: In the last 10 years the field of provenance analysis has undergone a revolution with the development of single-crystal isotopic dating techniques, the most common being U/Pb zircon and 40Ar/39Ar techniques. These have allowed age determination of single crystals thus providing more detail about probable provenance of each individual grain rather than an averaged population of grains. The usefulness for resolving complex terrane accretion and translation histories was immediately obvious and there have been many studies in many different regions aimed at tracking terrane motions by provenance of individual grains upward through the stratigraphy of a basin. Recent research in the North American Cordilleran terranes and in the New Zealand Torlesse Superterrane show how widely used and powerful these provenance analysis techniques are. However, isotopic provenance analysis has often been presented as key information to resolve controversies around terrane translation histories with very little discussion of the context of sedimentary facies and sediment transport mechanisms. An example is the recent use of U/Pb detrital zircon ages as the supposedly controversy-ending evidence for the amount of lateral translation of the Insular Superterrane in British Columbia (Baja BC) (Mahoney et al., 1999). The zircon grains were separated from fine-grained turbidite deposits and could easily have been transported over very large distances by a variety of mechanisms; yet they were presented as definitively resolving the Baja BC controversy. Modern examples illustrate the problem of using the provenance of fine grained sediment to constrain terrane tectonics. Sediment in the tip of the Bengal submarine fan was transported ∼3000 km from source, first by fluvial processes then by sediment gravity flow in the submarine fan. The detrital isotopic ages of single grains are the same as the depositional ages indicating a very rapid unroofing and transport rate with minimal

  13. Distribution and Diversity of Carboniferous and Permian Colonial Rugose Coral Faunas in Western North America: Clues for Placement of Allochthonous Terranes

    Directory of Open Access Journals (Sweden)

    Calvin H. Stevens

    2012-05-01

    Full Text Available Colonial rugose corals are common in western cratonal North America and in some of the allochthonous terranes, now amalgamated against its western margin. Throughout the Late Paleozoic, the coral faunas in these two different settings were significantly different. Comparisons of these faunas suggest that during the Mississippian the Alexander terrane probably was southwest of Arctic Alaska and the Stikine terrane probably lay west of the southern part of the North American craton. The Cache Creek terrane lay far out in the Paleopacific Ocean. The Pennsylvanian faunas suggest that the Quesnellia and Eastern Klamath terranes were situated southwest of Arctic Alaska and the Alexander terrane was somewhat farther southwest and farther from cratonal North America. The Stikine terrane continued to be positioned west of the southern part of the North American craton. During the Early Permian, terranes with a cratonal faunal aspect may have lain 2000–3000 km west of cratonal North America and latitudinally generally southwest of their present positions. In the Middle Permian these terranes were carried southward relative to the North American craton. Simultaneously the Tethyan Realm expanded eastward.

  14. Retrowedge-related Carboniferous units and coeval magmatism in the northwestern Neuquén province, Argentina

    Science.gov (United States)

    Zappettini, Eduardo O.; Chernicoff, Carlos J.; Santos, Joao O. S.; Dalponte, Marcelo; Belousova, Elena; McNaughton, Neal

    2012-11-01

    The studied Carboniferous units comprise metasedimentary (Guaraco Norte Formation), pyroclastic (Arroyo del Torreón Formation), and sedimentary (Huaraco Formation) rocks that crop out in the northwestern Neuquén province, Argentina. They form part of the basement of the Neuquén Basin and are mostly coeval with the Late Paleozoic accretionary prism complex of the Coastal Cordillera, south-central Chile. U-Pb SHRIMP dating of detrital zircon yielded a maximum depositional age of 374 Ma (Upper Devonian) for the Guaraco Norte Formation and 389 Ma for the Arroyo del Torreón Formation. Detrital magmatic zircon from the Guaraco Norte Formation are grouped into two main populations of Devonian and Ordovician (Famatinian) ages. In the Arroyo del Torreón Formation, zircon populations are also of Devonian and Ordovician (Famatinian), as well as of Late Neoproterozoic and Mesoproterozoic ages. In both units, there is a conspicuous population of Devonian magmatic zircon grains (from 406 ± 4 Ma to 369 ± 5 Ma), indicative of active magmatism at that time range. The ɛHf values of this population range between -2.84 and -0.7, and the TDM-(Hf) are mostly Mesoproterozoic, suggesting that the primary sources of the Devonian magmatism contained small amounts of Mesoproterozoic recycled crustal components. The chemical composition of the Guaraco Norte Formation corresponds to recycled, mature polycyclic sediment of mature continental provenance, pointing to a passive margin with minor inputs from continental margin magmatic rocks. The chemical signature of the Huaraco Formation indicates that a magmatic arc was the main provenance for sediments of this unit, which is consistent with the occurrence of tuff—mostly in the Arroyo del Torreón Formation and very scarcely in the Huaraco Formation—with a volcanic-arc signature, jointly indicating the occurrence of a Carboniferous active arc magmatism during the deposition of the two units. The Guaraco Norte Formation is interpreted

  15. Herpetological conservation in northwestern North America

    Science.gov (United States)

    Deanna H. Olson

    2009-01-01

    Conservation of the 105 species of amphibians, reptiles, and turtles in the northwestern United States and western Canada is represented by a diverse mix of projects and programs across ten states, provinces, and territories. In this paper, 29 contributing authors review the status of herpetofauna by state, province or territory, and summarize the key issues, programs...

  16. Agricultural credit repayment in Finoteselam town, northwestern ...

    African Journals Online (AJOL)

    ... of loans to consumption ends. Family planning, creating enabling conditions for insurance markets, and enhancing labour markets are areas of policy concerns that could further improve loan repayment performances. Key words: Agricultural credit, determinants, microfinance, ACSI, northwestern Ethiopia, Finoteselam ...

  17. Two possibilities for New Siberian Islands terrane tectonic history during the Early Paleozoic based on paleomagnetic data

    Science.gov (United States)

    Metelkin, Dmitry V.; Chernova, Anna I.; Vernikovsky, Valery A.; Matushkin, Nikolay Yu.

    2017-04-01

    The New Siberian Islands (NSI), located in the East Siberian Sea in the junction region of various structural elements, are a key target for deciphering the tectonic evolution of the Eastern Arctic. In recent years, we went on several expeditions and gathered an extensive geological material for this territory. Among other things, we could prove that the basement of the De Long and Anjou archipelagos structures is Precambrian and the overlying Paleozoic sections formed within the same terrane. The form of the boundaries of the NSI terrane are actively debated and are probably continued from the Lyakhovsky islands in the south-west to the southern parts of the submerged Mendeleev Ridge, for which there is increasing evidence of continental crust. Today there are several models that interpret the Paleozoic-Mesozoic tectonic history and structural affiliation of the NSI terrane. Some propose that the Paleozoic sedimentary section formed in a passive margin setting of the Siberian paleocontinent. Others compare its history with marginal basins of the Baltica and Laurentia continents or consider the NSI terrane as an element of the Chukotka-Alaska microplate. These models are mainly based on results of paleobiogeographical and lithological-facies analyses, including explanations of probable sources for detrital zircons. Our paleomagnetic research on sedimentary, volcanogenic-sedimentary and igneous rocks of the Anjou (Kotelny and Bel'kovsky islands) and De Long (Bennett, Jeannette and Henrietta islands) archipelagos let us calculate an apparent polar wander path for the early Paleozoic interval of geological history, which allows us to conclude that the NSI terrane could not have been a part of the continental plates listed above, but rather had active tectonic boundaries with them. Our paleomagnetic data indicate that the NSI terrane drifted slowly and steadily in the tropical and subtropical regions no higher than 40 degrees. However, the main uncertainty for the

  18. Low palaeoelevation of the northern Lhasa terrane during late Eocene: Fossil foraminifera and stable isotope evidence from the Gerze Basin.

    Science.gov (United States)

    Wei, Yi; Zhang, Kexin; Garzione, Carmala N; Xu, Yadong; Song, Bowen; Ji, Junliang

    2016-06-08

    The Lhasa terrane is a key region for understanding the paleoelevation of the southern Tibetan Plateau after India-Asia collision. The Gerze Basin, located in the northern part of the Lhasa terrane, is a shortening-related basin. We discovered Lagena laevis (Bandy) fossils in upper Eocene strata of the Gerze Basin. This type of foraminifera is associated with lagoon and estuarine environments, indicating that the northern part of the Lhasa terrane was near sea level during the late Eocene. We speculate that these foraminifera were transported inland by storm surges to low elevation freshwater lakes during times of marine transgressions. This inference is consistent with the relatively positive δ(18)O values in carbonate from the same deposits that indicate low palaeoelevations close to sea level. Considering the palaeoelevation results from the nearby Oligocene basins at a similar latitude and the volcanic history of the Lhasa terrane, we infer that large-magnitude surface uplift of the northern Lhasa terrane occurred between late Eocene and late Oligocene time.

  19. The Apuseni Mountains, Romania, a Variscan Collage of Ordovician Gondwanan Terranes

    Science.gov (United States)

    Balintoni, I. C.; Balica, C.; Zaharia, L.; Chen, F.; Cliveti, M.; Hann, H. P.; Ghergari, L.

    2007-12-01

    The basement of the Apuseni Mountains, Romania, consists of three pre-Variscan terranes, sutured during an Early Variscan amalgamation around 351 Ma (Balintoni et al., this volume). The northern Someş Terrane (ST) is predominantly gneissic, while the southern Baia de Arieş Terrane (BAT) is dominated by the presence of large carbonate lenses, although metagranites and other types of orthogneisses can be found. These two terranes are sutured through the Biharia terrane, probably an accreted island arc. LA-ICP-MS datings on zircons extracted from orthogneisses and metagranites were performed in order to constrain the age of ST and BAT. A number of previously CL-imaged crystals were ablated at the China's University of Geosciences, Wuhan. From ST we dated an orthogneiss occurring in structurally lowermost position, a metatuff situated in the upper strongly retrogressed part and a twenty detrital crystal population sampled from a metasandstone. The 206Pb/238U apparent ages were projected using the weighted average plots.A magmatic crystallization age of 472.8±5.0 Ma (Upper Early Ordovician) resulted for one of the orthogneiss samples, besides several older ages at 505.7, 566.3 and 708.2 Ma corresponding to inherited cores. Another sample from the same rock appeared strongly affected by lead loss during a later thermotectonic event, most of the apparent ages grouping around 352±14 Ma. This age is similar with the age of the suture between ST and BT (Balintoni et al., this volume). The main zircon population of one metatuff sample furnished an averaged age of 423±7.2 Ma, also found in two additional samples, but their significance is obscure for the moment. Two primary magmatic ages arise at 464.2 and 473.8 Ma, an older value of 758.7 Ma corresponding to an inherited core. Detrital zircon ages range between 534.8 and 2596.8 Ma. The younger value represents an upper age constraint for the protolith age of ST-rocks. From BAT we dated the Lupşa metaporphyroid and the

  20. Seismic signatures of the Pan-African orogeny: implications for southern Indian high-grade terranes

    Science.gov (United States)

    Rai, Abhishek; Gaur, V. K.; Rai, S. S.; Priestley, K.

    2009-02-01

    We present the results of a study designed to investigate and compare the seismic characteristics of the once contiguous terranes of eastern Gondwanaland, now incorporated in five separated continental masses, which, during the Neoproterozoic (~600Ma) Pan-African orogeny, suffered a high degree of thermal stress and deformation. Receiver functions and surface wave data from stations located in East Antarctica, Sri Lanka, the southern-Indian high-grade terranes, Madagascar and the Tanzania-Mozambique belt, were used to determine the shear-wave velocity structure, Moho depth and VP/VS values of the respective crustal segments. This study provides an additional dimension to the otherwise well-documented characteristic petrology of their surface exposures and other geological signatures such as their extensive granulitization and gem formation during the Pan-African event. Analysis of the receiver functions and surface wave data for these seismic stations located on their present day widely distributed continental fragments have been made. It is observed that with the exception of KOD (at Kodaikanal hill), situated on the southern Indian granulites having the thickest crust (~43.5 km), most of the Pan-African granulitic terranes have a crustal thicknesses of ~37 +/- 0.8km, with a transition to higher velocity at mid-crustal depths, and that their bulk composition is felsic. Average crustal VP/VS values (1.704 +/- 0.03) and thicknesses (37.8 +/- 0.8km), for four stations (SYO, PALK, TRV and ABPO), now located in East Antarctica, Sri Lanka, India and Madagascar, respectively, show remarkable similarity, indicating that the Pan-African orogeny was extensive enough to reorder the crustal structure of a wide region with a broadly similar stamp.

  1. Paleomagnetic Constraints on the Tectonic History of the Mesozoic Ophiolite and Arc Terranes of Western Mexico

    Science.gov (United States)

    Boschman, L.; Van Hinsbergen, D. J. J.; Langereis, C. G.; Molina-Garza, R. S.; Kimbrough, D. L.

    2017-12-01

    The North American Cordillera has been shaped by a long history of accretion of arcs and other buoyant crustal fragments to the western margin of the North American Plate since the Early Mesozoic. Accretion of these terranes resulted from a complex tectonic history interpreted to include episodes of both intra-oceanic subduction within the Panthalassa/Pacific Ocean, as well as continental margin subduction along the western margin of North America. Western Mexico, at the southern end of the Cordillera, contains a Late Cretaceous-present day long-lived continental margin arc, as well as Mesozoic arc and SSZ ophiolite assemblages of which the origin is under debate. Interpretations of the origin of these subduction-related rock assemblages vary from far-travelled exotic intra-oceanic island arc character to autochthonous or parautochthonous extended continental margin origin. We present new paleomagnetic data from four localities: (1) the Norian SSZ Vizcaíno peninsula Ophiolite; (2) its Lower Jurassic sedimentary cover; and (3) Barremian and (4) Aptian sediments derived from the Guerrero arc. The data show that the Mexican ophiolite and arc terranes have a paleolatitudinal plate motion history that is equal to that of the North American continent. This suggests that these rock assemblages were part of the overriding plate and were perhaps only separated from the North American continent by temporal fore- or back-arc spreading. These spreading phases resulted in the temporal existence of tectonic plates between the North American and Farallon Plates, and upon closure of the basins, in the growth of the North American continent without addition of any far-travelled exotic terranes.

  2. Piedra lata terrane of Uruguay: Rb-Sr geochronological data of two new paleoproterozoic (transamazonian) granitoids

    International Nuclear Information System (INIS)

    Cingolani, C; Bossi, J; Varela, R; Maldonado, S.; Pineyro, D.; Schipilov, A

    2001-01-01

    The Precambrian basement of Uruguay consists of three major terranes separated and crosscut by wide NE-striking subvertical transcurrent shear zones. The western terrane as a part of the Rio de la Plata Craton is known as the Piedra Alta Terrane (PAT). This is separated from the Nico Perez Terrane by the Sarandi del Yi-Piri olis subvertical shear zone (Bossi et al., 1993). A mafic dykes complex intruded the PAT at 1.8 Ga and was not later deformed. The PAT has equivalent rocks in the igneous-metamorphic basement of Tandilia region and the Martin Garcia Island, Buenos Aires Province, Argentina (Dalla Salda et al., 1988; Cingolani and Dalla Salda, 2000). The PAT shows no evidence of the Neoproterozoic orogenies and is considered a best preserved Paleoproterozoic block (Transamazonian Cycle). It contains three E-W trending belts of volcano-sedimentary rocks with low grade metamorphism. These are from south to north: Pando, San Jose and Andresito belts (Bossi et al., 1996). Associated with them, three granitic-gneissic zones he Ecilda Paullier, Florida and Feliciano- were recognized with magmatic intrusives emplaced at different crustal levels. The San Jose belt is the largest supracrustal unit and contains abundant volcanic and volcaniclastic rocks of low grade metamorphic (Paso Severino Fm.) with sheets of granitic rocks intercalated (Mutti et al., 1996; Bossi et al., 1996). The associated granitic rocks are of large areal extension, mostly granodiorites and tonalites, and minor monzogranite and gabbro (e.g. Cerro Rospide region), including xenoliths from Paso Severino Fm. Towards the north of the San Jose belt an important Florida granitized zone is developed in the central part of the PAT, where the Pintos massif was recognized. The main purpose of this contribution is to offer new Rb-Sr geochronological data from two granitoid units, The Cerro Rospide intrusive in Paso Severino Fm. and Pintos massif included in medium grade migmatic-metamorphic complex and its

  3. Interpretation of gravity profiles across the northern Oaxaca terrane, its boundaries and the Tehuacán Valley, southern Mexico

    Science.gov (United States)

    Campos-Enríquez, J. O.; Alatorre-Zamora, M. A.; Keppie, J. D.; Belmonte-Jiménez, S. I.; Ramón-Márquez, V. M.

    2014-12-01

    A gravity study was conducted across the northern Oaxaca terrane and its bounding faults: the Caltepec and Oaxaca Faults to the west and east, respectively. These faults juxtapose the Oaxaca terrane against the Mixteca and Juarez terranes, respectively. The Oaxaca Fault also forms the eastern boundary of the Cenozoic Tehuacán depression. On the west, at depth, the Tehuacán valley is limited by the normal buried Tehuacán Fault. This gravity study reveals that the Oaxaca Fault system gives rise to a series of east tilted basamental blocks (Oaxaca Complex). The tectonic depression is filled with Phanerozoic rocks and has a deeper depocenter to the west. The gravity data also indicate that on the west, the Oaxaca Complex, the Caltepec and Santa Lucia faults continue northwestwards beneath Phanerozoic rocks. A major E-W to NE-SW discontinuity is inferred to exist between profiles 1 and 2.

  4. Shallow magnetic inclinations in the Cretaceous Valle Group, Baja California: remagnetization, compaction, or terrane translation?

    Science.gov (United States)

    Smith, Douglas P.; Busby, Cathy J.

    1993-10-01

    Paleomagnetic data from Albian to Turonian sedimentary rocks on Cedros Island, Mexico (28.2° N, 115.2° W) support the interpretation that Cretaceous rocks of western Baja California have moved farther northward than the 3° of latitude assignable to Neogene oblique rifting in the Gulf of California. Averaged Cretaceous paleomagnetic results from Cedros Island support 20 ± 10° of northward displacement and 14 ± 7° of clockwise rotation with respect to cratonic North America. Positive field stability tests from the Vizcaino terrane substantiate a mid-Cretaceous age for the high-temperature characteristic remanent magnetization in mid-Cretaceous strata. Therefore coincidence of characteristic magnetization directions and the expected Quaternary axial dipole direction is not due to post mid-Cretaceous remagnetization. A slump test performed on internally coherent, intrabasinal slump blocks within a paleontologically dated olistostrome demonstrates a mid-Cretaceous age of magnetization in the Valle Group. The in situ high-temperature natural remanent magnetization directions markedly diverge from the expected Quaternary axial dipole, indicating that the characteristic, high-temperature magnetization was acquired prior to intrabasinal slumping. Early acquisition of the characteristic magnetization is also supported by a regional attitude test involving three localities in coherent mid-Cretaceous Valle Group strata. Paleomagnetic inclinations in mudstone are not different from those in sandstone, indicating that burial compaction did not bias the results toward shallow inclinations in the Vizcaino terrane.

  5. Terrane accumulation and collapse in central Europe: seismic and rheological constraints

    Science.gov (United States)

    Meissner, R.

    1999-05-01

    An attempt is made to compare the tectonic units and their evolution in central Europe with the deep seismic velocity structure and patterns of reflectivity. Caledonian and Variscan terrane accretion and orogenic collapse dominate the tectonic development in central and western Europe and have left their marks in a distinct velocity structure and crustal thickness as well as in the various reflectivity patterns. Whereas the memory of old collisional structures is still preserved in the rigid upper crust, collapse processes have formed and modified the lower crust. They have generally created rejuvenated, thin crusts with shallow Mohos. In the Variscan internides, the center of collision and post-orogenic heat pulses, the lower crust developed strong and thick seismic lamellae, the (cooler) externides show a thrust and shear pattern in the whole crust, and the North German Basin experienced large mafic intrusions in the lower crust and developed a high-velocity structure with only very thin lamellae on top of the Moho. The various kinds of reflectivity patterns in the lithosphere can be explained by a thermo-rheological model from terrane collision, with crustal thickening to collapse in a hot, post-orogenic setting.

  6. Tectonic superposition of the Kurosegawa Terrane upon the Sanbagawa metamorphic belt in eastern Shikoku, southwest Japan

    International Nuclear Information System (INIS)

    Suzuki, Hisashi; Isozaki, Yukio; Itaya, Tetsumaru.

    1990-01-01

    Weakly metamorphosed pre-Cenozoic accretionary complex in the northern part of the Chichibu Belt in Kamikatsu Town, eastern Shikoku, consists of two distinct geologic units; the Northern Unit and Southern Unit. The Northern Unit is composed mainly of phyllitic pelites and basic tuff with allochthonous blocks of chert and limestone, and possesses mineral paragenesis of the glaucophane schist facies. The Southern Unit is composed mainly of phyllitic pelites with allochthonous blocks of sandstone, limestone, massive green rocks, and chert, and possesses mineral paragenesis of the pumpellyite-actinolite facies. The Southern Unit tectonically overlies the Northern Univ by the south-dipping Jiganji Fault. K-Ar ages were dated for the recrystallized white micas from 11 samples of pelites and basic tuff in the Northern Unit, and from 6 samples of pelites in the Southern Unit. The K-Ar ages of the samples from the Northern Unit range in 129-112 Ma, and those from the Southern Unit in 225-194 Ma. In terms of metamorphic ages, the Northern Unit and Southern Unit are referred to the constituents of the Sanbagawa Metamorphic Belt, and to those of the Kurosegawa Terrane, respectively. Thus, tectonic superposition of these two units in the study area suggests that the Kurosegawa Terrane occurs in a higher structural position over the Sanbagawa Metamorphic Belt in eastern Shikoku. (author)

  7. Northwestern University trial emerging optical solutions

    CERN Multimedia

    2001-01-01

    Nortel Networks, SBC Ameritech and Northwestern University announced the creation of OMNInet (Optical Metro Network Initiative), a collaborative experimental network. The OMNInet technology trial, a four-site network located in Chicago, will provide a test bed for all-optical switching, advanced high-speed technology such as 10 gigabit Ethernet (10GE) and will test next-generation applications in healthcare, industrial design, finance and commerce.

  8. Demography of Dall's sheep in northwestern Alaska

    Science.gov (United States)

    Kleckner, Christopher; Udevitz, Mark S.; Adams, Layne G.; Shults, Brad S.

    2003-01-01

    Dall’s sheep in northwestern Alaska declined in the early 1990s following the severe 1989-90 and 1990-91 winters. In the Baird Mountains of Noatak National Preserve, estimates of adult sheep declined by 50% from 800 in 1989 to under 400 in 1991. Population counts remained low throughout 1991 to 1996, reaching a minimum of 244 adult sheep in 1996. Few lambs were observed during annual midsummer aerial surveys in 1991 to 1994. We suspect that these declines resulted from a combination of poorer nutritional condition and increased vulnerability of sheep to predation resulting from severe winter conditions.As a result of these declines, both subsistence and sport hunting seasons were closed by emergency order in 1991, resulting in substantial management controversy. The affected publics, although willing to accept the closures, questioned the validity of the sheep survey data and strongly emphasized their interest in restoring harvests as soon as populations increased sufficiently. In 1995 the Northwest Arctic Regional Advisory Council, the local advisory committee for the Federal Subsistence Board, passed a motion supporting efforts to initiate research on sheep populations in the region to better understand the factors limiting sheep populations and to evaluate sheep survey methodologies.Currently estimates of Dall’s sheep population size and composition in the western Brooks Range are based on intensive fixed-wing aerial surveys conducted annually since 1986 in areas including the Baird Mountains. The annual variation in recent Baird Mountains aerial counts cannot be explained with reasonable assumptions about reproduction and survival, suggesting that there is some variability in the proportion of the population observed each year or that a substantial number of sheep move during the survey. Prior to our research, no attempt had been made to estimate visibility bias or precision for these surveys.Our understanding of Dall’s sheep population biology comes

  9. Contrasting styles of sedimentation and deformation in the Chugach Terrane accretionary complex, south-central Alaska

    Science.gov (United States)

    Amato, J. M.; Pavlis, T. L.; Worthman, C.; Kochelek, E.; Day, E. M.; Clift, P. D.; Hecker, J.

    2011-12-01

    In southeast Alaska the Chugach terrane represents an accretionary complex associated with several arcs active at 200-65 Ma. This lithostratigraphic unit consists of blueschists with Early Jurassic metamorphic ages and uncertain depositional ages; the Jurassic-Cretaceous McHugh Complex; and the Late Cretaceous Valdez Group. Detrital zircon ages from densely sampled transects reveals patterns in the assembly of the complex. Blueschists are almost totally barren of zircon, suggesting protoliths derived from mafic-intermediate volcanic protoliths far from a continental source. There is an age gap between the blueschists and the McHugh complex interpreted to be caused by an episode of tectonic erosion. The McHugh Complex is two separate units that are lithologically and geochronologically distinct. The older McHugh is a melange is dominated by stratally disrupted volcanic rocks, chert, and argillite. The oldest McHugh rocks have maximum depositional ages (MDA) of 177-150 Ma at Seldovia and 157-145 Ma at Turnagain Arm; the lack of older rocks at Turnagain Arm suggests removal of structural section by faulting. The MDAs of the older McHugh rocks do not decrease progressively away from the arc. There is a 45 m.y. gap in MDA between the older McHugh and the Late Cretaceous McHugh rocks. The younger McHugh rocks are dominated by volcanogenic sandstone and coarse conglomerate and MDA decreases from 100 Ma near the boundary with the older McHugh mesomelange to 85 Ma near the Valdez Group. The Valdez Group consists of coherently bedded turbidites with a MDA range of 85-60 Ma that decreases progressively outboard of the arc source. A sample from the Orca Group of the Prince William terrane is lithologically similar to the Valdez Group and there is no gap in MDA between Valdez and Orca Groups. 55 Ma dikes cut the McHugh and Valdez Groups in the western Chugach and Kenai Mountains. The oldest units of the Chugach terrane are the most deformed, with deformation and metamorphism

  10. Gamma-ray spectrometry of granitic suites of the Paranaguá Terrane, Southern Brazil

    Science.gov (United States)

    Weihermann, Jessica Derkacz; Ferreira, Francisco José Fonseca; Cury, Leonardo Fadel; da Silveira, Claudinei Taborda

    2016-09-01

    The Paranaguá Terrane, located in the coastal portion of the states of Santa Catarina, Paraná and São Paulo in Southern Brazil is a crustal segment constituted mainly by an igneous complex, with a variety of granitic rocks inserted into the Serra do Mar ridge. The average altitude is approximately 1200 m above sea level, with peaks of up to 1800 m. Due to the difficulty of accessing the area, a shortage of outcrops and the thick weathering mantle, this terrane is understudied. This research aims to evaluate the gamma-ray spectrometry data of the granitic suites of the Paranaguá Terrane, in correspondence with the geological, petrographical, lithogeochemical, relief and mass movement information available in the literature. Aerogeophysical data were acquired along north-south lines spaced at 500 m, with a mean terrain clearance of 100 m. These data cover potassium (K, %), equivalent in thorium (eTh, ppm) and equivalent in uranium (eU, ppm). After performing a critical analysis of the data, basic (K, eU, eTh) and ternary (R-K/G-eTh/B-eU) maps were generated and then superimposed on the digital elevation model (DEM). The investigation of the radionuclide mobility across the relief and weathering mantle consisted of an analysis of the schematic profiles of elevation related with each radionuclide; a comparison of the K, eU and eTh maps with their 3D correspondents; and the study of mass movements registered in the region. A statistical comparison of lithogeochemical (K, U, Th) and geophysical (K, eU, eTh) data showed consistency in all the granitic suites studied (Morro Inglês, Rio do Poço and Canavieiras-Estrela). Through gamma-ray spectrometry, it was possible to establish relationships between scars (from mass movements) and the gamma-ray responses as well as the radionuclide mobility and the relief and to map the granitic bodies.

  11. Cretaceous–Eocene provenance connections between the Palawan Continental Terrane and the northern South China Sea margin

    NARCIS (Netherlands)

    Shao, Lei; Cao, Licheng; Qiao, Peijun; Zhang, Xiangtao; Li, Qianyu; van Hinsbergen, Douwe J.J.

    2017-01-01

    The plate kinematic history of the South China Sea opening is key to reconstructing how the Mesozoic configuration of Panthalassa and Tethyan subduction systems evolved into today's complex Southeast Asian tectonic collage. The South China Sea is currently flanked by the Palawan Continental Terrane

  12. Paleozoic subduction complex and Paleozoic-Mesozoic island-arc volcano-plutonic assemblages in the northern Sierra terrane

    Science.gov (United States)

    Hanson, Richard E.; Girty, Gary H.; Harwood, David S.; Schweickert, Richard A.

    2000-01-01

    This field trip provides an overview of the stratigraphic and structural evolution of the northern Sierra terrane, which forms a significant part of the wall rocks on the western side of the later Mesozoic Sierra Nevada batholith in California. The terrane consists of a pre-Late Devonian subduction complex (Shoo Fly Complex) overlain by submarine arc-related deposits that record the evolution of three separate island-arc systems in the Late Sevonian-Early Mississippian, Permian, and Late Triassic-Jurassic. The two Paleozoic are packages and the underlying Shoo Fly Complex have an important bearing on plate-tectonic processes affecting the convergent margin outboard of the Paleozoic Cordilleran miogeocline, although their original paleogeographic relations to North America are controversial. The third arc package represents an overlap assemblage that ties the terrane to North America by the Late Triassic and helps constrain the nature and timing of Mesozoic orogenesis. Several of the field-trip stops examine the record of pre-Late Devonian subduction contained in the Shoo Fly Complex, as well as the paleovolcanology of the overlying Devonian to Jurassic arc rocks. Excellent glaciated exposures provide the opportunity to study a cross section through a tilted Devonian volcano-plutonic association. Additional stops focus on plutonic rocks emplaced during the Middle Jurassic arc magmatism in the terrane, and during the main pulse of Cretaceous magmatism in the Sierra Nevada batholith to the east.

  13. Microprobe monazite constraints for and early (ca. 790 Ma) Braziliano orogeny: The Embu Terrane, southeastern Brazil

    International Nuclear Information System (INIS)

    Vlach, Silvio R.F

    2001-01-01

    The evolution of the Mantiqueira Orogenetic System, Southeastern Brazil, comprises discrete episodes of tectonic collage and docking of remnants of Rodinia break-up in the borders of the Sao Francisco Craton. This system is related to the closure of the Adamastor ocean and assemblage of the western Gondwana super-continent during Neoproterozoic times (ca. 610-530 Ma, Brito Neves et al., 1999; Campos Neto, 2000). This report presents monazite microprobe dating results for metassediments from the Embu Complex, an important lithological unit from the Ribeira Belt, currently included in the Juiz de Fora terrane, a unit added to the Sao Francisco Craton at ca. 600-580 Ma. (Campos Neto, 2000). The age results unravel a main metamorphic episode and related orogeny at ca. 790 Ma and bring new insights concerning the agglutination of Gondwana in this region during the Neoproterozoic (au)

  14. Paleointensity determination on Neoarchaean dikes within the Vodlozerskii terrane of the Karelian craton

    Science.gov (United States)

    Shcherbakova, V. V.; Lubnina, N. V.; Shcherbakov, V. P.; Zhidkov, G. V.; Tsel'movich, V. A.

    2017-09-01

    The results of paleomagnetic studies and paleointensity determinations from two Neoarchaean Shala dikes with an age of 2504 Ma, located within the Vodlozerskii terrane of the Karelian craton, are presented. The characteristic components of primary magnetization with shallow inclinations I = -5.7 and 1.9 are revealed; the reliability of the determinations is supported by two contact tests. High paleointensity values are obtained by the Thellier-Coe and Wilson techniques. The calculated values of the virtual dipole moment (11.5 and 13.8) × 1022 A m2 are noticeably higher than the present value of 7.8 × 1022 A m2. Our results, in combination with the previous data presented in the world database, support the hypothesized existence of a period of high paleointensity in the Late Archaean-Early Proterozoic.

  15. kepler's dark worlds: A low albedo for an ensemble of Neptunian and Terran exoplanets

    Science.gov (United States)

    Jansen, Tiffany; Kipping, David

    2018-05-01

    Photometric phase curves provide an important window onto exoplanetary atmospheres and potentially even their surfaces. With similar amplitudes to occultations but far longer baselines, they have a higher sensitivity to planetary photons at the expense of a more challenging data reduction in terms of long-term stability. In this work, we introduce a novel non-parametric algorithm dubbed phasma to produce clean, robust exoplanet phase curves and apply it to 115 Neptunian and 50 Terran exoplanets observed by kepler. We stack the signals to further improve signal-to-noise, and measure an average Neptunian albedo of Ag greenhouse effect, our work implies that kepler's solid planets are unlikely to resemble cloudy Venusian analogs, but rather dark Mercurian rocks.

  16. Are turtleback fault surfaces common structural elements of highly extended terranes?

    Science.gov (United States)

    Çemen, Ibrahim; Tekeli, Okan; Seyitoğlu, Gűrol; Isik, Veysel

    2005-12-01

    The Death Valley region of the U.S.A. contains three topographic surfaces resembling the carapace of a turtle. These three surfaces are well exposed along the Black Mountain front and are named the Badwater, Copper Canyon, and Mormon Point Turtlebacks. It is widely accepted that the turtlebacks are also detachment surfaces that separate brittlely deformed Cenozoic volcanic and sedimentary rocks of the hanging wall from the strongly mylonitic, ductilely deformed pre-Cenozoic rocks of the footwall. We have found a turtleback-like detachment surface along the southern margin of the Alasehir (Gediz) Graben in western Anatolia, Turkey. This surface qualifies as a turtleback fault surface because it (a) is overall convex-upward and (b) separates brittlely deformed hanging wall Cenozoic sedimentary rocks from the ductilely to brittlely deformed, strongly mylonitic pre-Cenozoic footwall rocks. The surface, named here Horzum Turtleback, contains striations that overprint mylonitic stretching lineations indicating top to the NE sense of shear. This suggests that the northeasterly directed Cenozoic extension in the region resulted in a ductile deformation at depth and as the crust isostatically adjusted to the removal of the rocks in the hanging wall of the detachment fault, the ductilely deformed mylonitic rocks of the footwall were brought to shallower depths where they were brittlely deformed. The turtleback surfaces have been considered unique to the Death Valley region, although detachment surfaces, rollover folds, and other extensional structures have been well observed in other extended terranes of the world. The presence of a turtleback fault surface in western Anatolia, Turkey, suggests that the turtleback faults may be common structural features of highly extended terranes.

  17. Age and duration of eclogite-facies metamorphism, North Qaidam HP/UHP terrane, Western China

    Science.gov (United States)

    Mattinson, C.G.; Wooden, J.L.; Liou, J.G.; Bird, D.K.; Wu, C.L.

    2006-01-01

    Amphibolite-facies para-and orthogneisses near Dulan, at the southeast end of the North Qaidam terrane, enclose minor eclogite and peridotite which record ultra-high pressure (UHP) metamorphism associated with the Early Paleozoic continental collision of the Qilian and Qaidam microplates. Field relations and coesite inclusions in zircons from paragneiss suggest that felsic, mafic, and ultramafic rocks all experienced UHP metamorphism and a common amphibolite-facies retrogression. SHRIMP-RG U-Pb and REE analyses of zircons from four eclogites yield weighted mean ages of 449 to 422 Ma, and REE patterns (flat HREE, no Eu anomaly) and inclusions of garnet, omphacite, and rutile indicate these ages record eclogite-facies metamorphism. The coherent field relations of these samples, and the similar range of individual ages in each sample suggests that the ???25 m.y. age range reflects the duration of eclogite-facies conditions in the studied samples. Analyses from zircon cores in one sample yield scattered 433 to 474 Ma ages, reflecting partial overlap on rims, and constrain the minimum age of eclogite protolith crystallization. Inclusions of Th + REE-rich epidote, and zircon REE patterns are consistent with prograde metamorphic growth. In the Lu??liang Shan, approximately 350 km northwest in the North Qaidam terrane, ages interpreted to record eclogite-facies metamorphism of eclogite and garnet peridotite are as old as 495 Ma and as young as 414 Ma, which suggests that processes responsible for extended high-pressure residence are not restricted to the Dulan region. Evidence of prolonged eclogite-facies metamorphism in HP/UHP localities in the Northeast Greenland eclogite province, the Western Gneiss Region of Norway, and the western Alps suggests that long eclogite-facies residence may be globally significant in continental subduction/collision zones.

  18. Geophysical modeling of the northern Appalachian Brompton-Cameron, Central Maine, and Avalon terranes under the New Jersey Coastal Plain

    Science.gov (United States)

    Maguire, T.J.; Sheridan, R.E.; Volkert, R.A.

    2004-01-01

    A regional terrane map of the New Jersey Coastal Plain basement was constructed using seismic, drilling, gravity and magnetic data. The Brompton-Cameron and Central Maine terranes were coalesced as one volcanic island arc terrane before obducting onto Laurentian, Grenville age, continental crust in the Taconian orogeny [Rankin, D.W., 1994. Continental margin of the eastern United States: past and present. In: Speed, R.C., (Ed.), Phanerozoic Evolution of North American Continent-Ocean Transitions. DNAG Continent-Ocean Transect Volume. Geological Society of America, Boulder, Colorado, pp. 129-218]. Volcanic island-arc rocks of the Avalon terrane are in contact with Central Maine terrane rocks in southern Connecticut where the latter are overthrust onto the Brompton-Cameron terrane, which is thrust over Laurentian basement. Similarities of these allochthonous island arc terranes (Brompton-Cameron, Central Maine, Avalon) in lithology, fauna and age suggest that they are faulted segments of the margin of one major late Precambrian to early Paleozoic, high latitude peri-Gondwana island arc designated as "Avalonia", which collided with Laurentia in the early to middle Paleozoic. The Brompton Cameron, Central Maine, and Avalon terranes are projected as the basement under the eastern New Jersey Coastal Plain based on drill core samples of metamorphic rocks of active margin/magmatic arc origin. A seismic reflection profile across the New York Bight traces the gentle dipping (approximately 20 degrees) Cameron's Line Taconian suture southeast beneath allochthonous Avalon and other terranes to a 4 sec TWTT depth (approximately 9 km) where the Avalonian rocks are over Laurentian crust. Gentle up-plunge (approximately 5 degrees) projections to the southwest bring the Laurentian Grenville age basement and the drift-stage early Paleozoic cover rocks to windows in Burlington Co. at approximately 1 km depth and Cape May Co. at approximately 2 km depths. The antiformal Shellburne

  19. Geology and metallogeny of the Ar Rayn terrane, eastern Arabian shield: Evolution of a Neoproterozoic continental-margin arc during assembly of Gondwana within the East African orogen

    Science.gov (United States)

    Doebrich, J.L.; Al-Jehani, A. M.; Siddiqui, A.A.; Hayes, T.S.; Wooden, J.L.; Johnson, P.R.

    2007-01-01

    The Neoproterozoic Ar Rayn terrane is exposed along the eastern margin of the Arabian shield. The terrane is bounded on the west by the Ad Dawadimi terrane across the Al Amar fault zone (AAF), and is nonconformably overlain on the east by Phanerozoic sedimentary rocks. The terrane is composed of a magmatic arc complex and syn- to post-orogenic intrusions. The layered rocks of the arc, the Al Amar group (>689 Ma to ???625 Ma), consist of tholeiitic to calc-alkaline basaltic to rhyolitic volcanic and volcaniclastic rocks with subordinate tuffaceous sedimentary rocks and carbonates, and are divided into an eastern and western sequence. Plutonic rocks of the terrane form three distinct lithogeochemical groups: (1) low-Al trondhjemite-tonalite-granodiorite (TTG) of arc affinity (632-616 Ma) in the western part of the terrane, (2) high-Al TTG/adakite of arc affinity (689-617 Ma) in the central and eastern part of the terrane, and (3) syn- to post-orogenic alkali granite (607-583 Ma). West-dipping subduction along a trench east of the terrane is inferred from high-Al TTG/adakite emplaced east of low-Al TTG. The Ar Rayn terrane contains significant resources in epithermal Au-Ag-Zn-Cu-barite, enigmatic stratiform volcanic-hosted Khnaiguiyah-type Zn-Cu-Fe-Mn, and orogenic Au vein deposits, and the potential for significant resources in Fe-oxide Cu-Au (IOCG), and porphyry Cu deposits. Khnaiguiyah-type deposits formed before or during early deformation of the Al Amar group eastern sequence. Epithermal and porphyry deposits formed proximal to volcanic centers in Al Amar group western sequence. IOCG deposits are largely structurally controlled and hosted by group-1 intrusions and Al Amar group volcanic rocks in the western part of the terrane. Orogenic gold veins are largely associated with north-striking faults, particularly in and near the AAF, and are presumably related to amalgamation of the Ar Rayn and Ad Dawadimi terranes. Geologic, structural, and metallogenic

  20. Biogeochemistry of a treeline watershed, northwestern Alaska.

    Science.gov (United States)

    Stottlemyer, R

    2001-01-01

    Since 1950, mean annual temperatures in northwestern Alaska have increased. Change in forest floor and soil temperature or moisture could alter N mineralization rates, production of dissolved organic carbon (DOC) and organic nitrogen (DON), and their export to the aquatic ecosystem. In 1990, we began study of nutrient cycles in the 800-ha Asik watershed, located at treeline in the Noatak National Preserve, northwestern Alaska. This paper summarizes relationships between topographic aspect, soil temperature and moisture, inorganic and organic N pools, C pools, CO2 efflux, growing season net N mineralization rates, and stream water chemistry. Forest floor (O2) C/N ratios, C pools, temperature, and moisture were greater on south aspects. More rapid melt of the soil active layer (zone of annual freeze-thaw) and permafrost accounted for the higher moisture. The O2 C and N content were correlated with moisture, inorganic N pools, CO2 efflux, and inversely with temperature. Inorganic N pools were correlated with temperature and CO2 efflux. Net N mineralization rates were positive in early summer, and correlated with O2 moisture, temperature, and C and N pools. Net nitrification rates were inversely correlated with moisture, total C and N. The CO2 efflux increased with temperature and moisture, and was greater on south aspects. Stream ion concentrations declined and DOC increased with discharge. Stream inorganic nitrogen (DIN) output exceeded input by 70%. Alpine stream water nitrate (NO3-) and DOC concentrations indicated substantial contributions to the watershed DIN and DOC budgets.

  1. Paleomagnetic contributions to the Klamath Mountains terrane puzzle-a new piece from the Ironside Mountain batholith, northern California

    Science.gov (United States)

    Mankinen, Edward A.; Gromme, C. Sherman; Irwin, W. Porter

    2013-01-01

    We obtained paleomagnetic samples from six sites within the Middle Jurassic Ironside Mountain batholith (~170 Ma), which constitutes the structurally lowest part of the Western Hayfork terrane, in the Klamath Mountains province of northern California and southern Oregon. Structural attitudes measured in the coeval Hayfork Bally Meta-andesite were used to correct paleomagnetic data from the batholith. Comparing the corrected paleomagnetic pole with a 170-Ma reference pole for North America indicates 73.5° ± 10.6° of clockwise rotation relative to the craton. Nearly one-half of this rotation may have occurred before the terrane accreted to the composite Klamath province at ~168 Ma. No latitudinal displacement of the batholith was detected.

  2. Punta del este terrane: meso proterozoic basement and neo proterozoic cover

    International Nuclear Information System (INIS)

    Preciozzi, F.; Sanchez Bettucci, L.; Basei, M.; Peel, E.; Oyhantcabal, P.; Cordani, U.

    2003-01-01

    Full text: Eastern basement of Uruguay consists of Meso and Neoproterozoic rocks. Mesoproterozoic basement had been deformed by pre-Brasiliano and Brasiliano events. Regional variations in this basement and in the Neoproterozoic cover show equivalent deformation styles and intensities. Models proposed for tectonic evolution have been scarce and confusing. Specially, the ones that concern the moment of collision and/or juxtaposition of blocks. The Punta del Este Terrane (PET) is composed of gneisses and migmatites formed between 1000 Ma to 900 Ma (Preciozzi et al., 2001). These rocks had been strongly reworked during Brasiliano and Rio Doce orogenesis (ca. 900-500 Ma). This crustal segment represents a high grade metamorphic terrane, which is correlated to some gneissic complexes southwest of Africa. Particularly, it is correlated to Kibaran-Namaqua Belt in Namibia. U-Pb ages between 1000 Ma and 900 Ma, obtained in zircons from tonalitic granitoids, are interpreted as indicative of their crystallization (Fig. 1). Besides, anatectic fluids related to migmatites leucosomes yielded ages of ca. 520 to 540 Ma. This denotes that superimposed metamorphic conditions during Brasiliano orogenesis reached, at least, lower amphibolite facies. PET basement gneisses present Sm-Nd model ages (TDM) between 2.4 to 1.8 Ga, showing long crustal residence, corroborated by the very negative εNd values of –1.3 and –14.3. During Brazilian orogenesy they were affected by deformation processes and anatexis. Metasedimentary PET cover occurs near La Paloma and Rocha towns. It is represented by a siliciclastic metasedimentary succession corresponding to the Rocha formation. In La Pedrera town recognized three sedimentary facies were (1-3): (1) sandstones and pelites; (2) green pelites; and (3) rhytmites. The transition from facies (1) to facies (3) shows the passage from fluvial environment with tidal influence to tidal flat with predominance of sub tidal deposits (Pazos and S

  3. Lithospheric discontinuities beneath the U.S. Midcontinent - signatures of Proterozoic terrane accretion and failed rifting

    Science.gov (United States)

    Chen, Chen; Gilbert, Hersh; Fischer, Karen M.; Andronicos, Christopher L.; Pavlis, Gary L.; Hamburger, Michael W.; Marshak, Stephen; Larson, Timothy; Yang, Xiaotao

    2018-01-01

    Seismic discontinuities between the Moho and the inferred lithosphere-asthenosphere boundary (LAB) are known as mid-lithospheric discontinuities (MLDs) and have been ascribed to a variety of phenomena that are critical to understanding lithospheric growth and evolution. In this study, we used S-to-P converted waves recorded by the USArray Transportable Array and the OIINK (Ozarks-Illinois-Indiana-Kentucky) Flexible Array to investigate lithospheric structure beneath the central U.S. This region, a portion of North America's cratonic platform, provides an opportunity to explore how terrane accretion, cratonization, and subsequent rifting may have influenced lithospheric structure. The 3D common conversion point (CCP) volume produced by stacking back-projected Sp receiver functions reveals a general absence of negative converted phases at the depths of the LAB across much of the central U.S. This observation suggests a gradual velocity decrease between the lithosphere and asthenosphere. Within the lithosphere, the CCP stacks display negative arrivals at depths between 65 km and 125 km. We interpret these as MLDs resulting from the top of a layer of crystallized melts (sill-like igneous intrusions) or otherwise chemically modified lithosphere that is enriched in water and/or hydrous minerals. Chemical modification in this manner would cause a weak layer in the lithosphere that marks the MLDs. The depth and amplitude of negative MLD phases vary significantly both within and between the physiographic provinces of the midcontinent. Double, or overlapping, MLDs can be seen along Precambrian terrane boundaries and appear to result from stacked or imbricated lithospheric blocks. A prominent negative Sp phase can be clearly identified at 80 km depth within the Reelfoot Rift. This arrival aligns with the top of a zone of low shear-wave velocities, which suggests that it marks an unusually shallow seismic LAB for the midcontinent. This boundary would correspond to the top of a

  4. Preliminary bathymetry of Northwestern Fiord and Neoglacial changes of Northwestern Glacier

    Science.gov (United States)

    Post, Austin

    1980-01-01

    The first preliminary bathymetry (at 1:20,000 scale) and other scientific investigations of Northwestern Fiord, Alaska, were conducted by the Research Vessel Growler in 1978, disclosing this 10.5-mile-long branched waterway to be a deep basin enclosed by a terminal-moraine shoal. The basin was formerly filled by Northwestern Glacier, which began a drastic retreat around 1909 and reached the head of the main arm around 1960. Soundings and profiles show the main channel to be as much as 970 feet deep and to have the typical U shape of a severely glacially eroded valley; since the glacier 's retreat, sediments have formed nearly level deposits in the deepest reaches, while the rest of the basin has a hard, rocky bottom. Preneoglacial forest debris dated by carbon-14 indicates Northwestern Glacier to have advanced into the fiord prior to 1,385 years before present (B.P.); a branch glacier evidently advanced into forest 1,635 years B.P. The combined glaciers from several arms culminated on the present terminal-moraine shoal around 1894. (USGS)

  5. Terrane Boundary Geophysical Signatures in Northwest Panay, Philippines: Results from Gravity, Seismic Refraction and Electrical Resistivity Investigations

    Directory of Open Access Journals (Sweden)

    Jillian Aira S. Gabo

    2015-01-01

    Full Text Available Northwest Panay consists of two terranes that form part of the Central Philippine collision zone: Buruanga Peninsula and Antique Range. The Buruanga Peninsula consists of a Jurassic chert-clastic-limestone sequence, typical of oceanic plate stratigraphy of the Palawan Micro-continental Block. The Antique Range is characterized by Antique Ophiolite Complex peridotites and Miocene volcanic and clastic rocks, representing obducted oceanic crust that serves as the oceanic leading edge of the collision with the Philippine Mobile Belt. The Nabas Fault is identified as the boundary between the two terranes. This study employed the gravity method to characterize the Northwest Panay subsurface structure. Results indicate higher Bouguer anomaly values for Buruanga Peninsula than those for Antique Range, separated by a sudden decrease in gravity values toward the east-southeast (ESE direction. Forward gravity data modeling indicates the presence of an underlying basaltic subducted slab in the Buruanga Peninsula. Furthermore, the Nabas Fault is characterized as an east-dipping thrust structure formed by Buruanga Peninsula basement leading edge subduction beneath Antique Range. Additional geophysical constraints were provided by shallow seismic refraction and electrical resistivity surveys. Results from both methods delineated the shallow subsurface signature of the Nabas Fault buried beneath alluvium deposits. The gravity, seismic refraction and electrical resistivity methods were consistent in identifying the Nabas Fault as the terrane boundary between the Buruanga Peninsula and the Antique Range. The three geophysical methods helped constrain the subsurface configuration in Northwest Panay.

  6. Uranium geochemical exploration in northwestern Luzon

    International Nuclear Information System (INIS)

    Santos, G. Jr.; Fernandez, L.; Ogena, M.; Tauli, G.

    1980-01-01

    A reconnaissance geochemical stream water and sediment survey which was conducted in northwestern Luzon was able to detect ten (10) uranium anomalous areas. These anomalous areas are located along a north-south trending zone of Miocene marine clastics and sedimentary rocks with tuffaceous sediment intercalations. In general, northwest Luzon has low radioactivity except for two anomalous areas which have 3 to 6 times background radioactivity. Radon anomalies occur in sparsely scattered locations. The anomalous zones appear to be related to major north-south faults and secondary northeast-southwest trending structures. Geochemical correlations between uranium and other elements such as copper, lead, zinc, manganese, silver, cobalt and nickel are generally very poor. (author)

  7. Post-peak metamorphic evolution of the Sumdo eclogite from the Lhasa terrane of southeast Tibet

    Science.gov (United States)

    Cao, Dadi; Cheng, Hao; Zhang, Lingmin; Wang, Ke

    2017-08-01

    A reconstruction of the pressure-temperature-time (P-T-t) path of high-pressure eclogite-facies rocks in subduction zones may reveal important information about the tectono-metamorphic processes that occur at great depths along the plate interface. The majority of studies have focused on prograde to peak metamorphism of these rocks, whereas after-peak metamorphism has received less attention. Herein, we present a detailed petrological, pseudosection modeling and radiometric dating study of a retrograded eclogite sample from the Sumdo ultrahigh pressure belt of the Lhasa terrane, Tibet. Mineral chemical variations, textural discontinuities and thermodynamic modeling suggest that the eclogite underwent an exhumation-heating period. Petrographic observations and phase equilibria modeling suggest that the garnet cores formed at the pressure peak (∼2.5 GPa and ∼520 °C) within the lawsonite eclogite-facies and garnet rims (∼1.5 GPa and spans an interval of ∼7 million years, which is a minimum estimate of the duration of the eclogite-facies metamorphism of the Sumdo eclogite.

  8. UTE park group and other meso proterozoic units of the Nico Perez terrane: Rodina connecting

    International Nuclear Information System (INIS)

    Gaucher, C; Chemale, F.; Bossi, J.; Sial, A.; Chiglino, L.

    2010-01-01

    The Parque UTE Group is a volcano sedimentary succession metamorphosed in green schist facies, comprising (from base to top): the Canada Espinillo Formation (prasinites, pelites, andesite s), the Mina Valencia Formation (dolostones, limestones, marls) and the Cerro del Mast il Formation (black pelites, limestones, acid tuffs). Thickness of the GPU exceeds 2.5 km; base and top are not exposed. U-Pb zircon ages for basic magmatic rocks at the base and rhyolites at the top yielded 1492±4 and 1429±21 Ma, respectively. 13C values of carbonates of the Pug are characterized by a plateau at +1‰ VPDB, bracketed between two negative excursions.These values are consistent with an early Mesoproterozoic depositional age. Detrital zircon age spectra show that the source area of the GPU was the Nico Perez Terrane, being thus native to the Rio de la Plata Craton (Rpc). A Mesoproterozoic tectonic event at 1.25 Ga, recorded at both sides of the Sarandi del Yi mega shear, is discussed. New U-Pb zircon ages are presented for the La China Complex at its type area, where a schistosity N60W cuts the metamorphic banding and is parallel to thrusts dated K-Ar at 1253±32 Ma. The ages obtained are: 3096±45 Ma (main metamorphic event) and 1252 Ma (lower intercept). These data confirm the occurrence of a Grenvillian-aged tectonic event in Uruguay, suggesting that the RPC was part of the super continent Rodinia

  9. Cenozoic geology of the Yolomécatl-Tlaxiaco area, Northwestern Oaxaca, Southeastern Mexico: Stratigraphy, structure and regional significance

    Science.gov (United States)

    Ferrusquía-Villafranca, Ismael; Ruiz-González, José E.; Torres-Hernández, José Ramón; Anderson, Thomas H.; Urrutia-Fucugauchi, Jaime; Martínez-Hernández, Enrique; García-Villegas, Felipe

    2016-12-01

    The Yolomécatl-Tlaxiaco Area, lies in the rugged Sierra Madre del Sur (SMS) of northwestern Oaxaca (YOTLA), southeastern Mexico. Within the area Cenozoic units unconformably overlie metamorphic, clastic and carbonate rock units of Late Paleozoic to Cretaceous ages as well as the Mixteco/Oaxaca Terrane boundary. The Cenozoic sequence, emphasized herein, includes from botton to top: (1) basal, calcilithitic Early Tertiary Tamazulapam Conglomerate, (2) andesitic lava flows of Nduayaco "Group," (3-4) Epiclastic/pyroclastic strata composing Yolomécatl Formation (∼40.3 ± 1.0 Ma), and Tayata Pyroepiclastics (5) Early Oligocene (∼32.9 Ma), felsic, pyroclastic Nundichi "Group," (6) Late Oligocene (∼27.7 ± 0.7 Ma) andesitic lava flows of Nicananduta "Group" containing intercalations of unit (7) ?Chilapa Formation (largely lacustrine). Quaternary deposits unconformably overlie the sequence. The structural record includes NNW-SSE folds in the Mesozoic units, and one in Tayata Pyroepiclastics, as well as numerous fractures/faults of diverse types, whose pattern seems to roughly define four geographic/structural domains, NW, SW, S, and E. The Tertiary sequence records four magmatic and six deformational events: Pre-Late Eocene Extension accommodated by the Tamazulapam fault, along which magma of the Nduayaco "Group" moved upward. The next episode is the earliest Late Eocene extension recorded by the Yucuxaco-Santa Cruz Tayata fault was followed by accumulation of Yolomécatl Formation, Tayata Pyroepiclastics, and synsedimentary emplacement of tuff sheets at ∼40.3 ± 1.0 Ma. After this date, left lateral transpression emplaced a Teposcolula Limestone block over Nduayaco "Group" and ?Yolomécatl Formation, whereas the Tayata Pyroepiclastics was folded into an open anticline. Movement along the Yucuxaco-Santa Cruz Tayayata fault suite influenced accumulation of the Nundichi "Group" strata ca. ∼32.9 Ma. Subsequent ENE-WSW extension affected the Nundichi "Group," partly

  10. Combined U-Pb SHRIMP and Hf isotope study of the Late Paleozoic Yaminué Complex, Rio Negro Province, Argentina: Implications for the origin and evolution of the Patagonia composite terrane

    Directory of Open Access Journals (Sweden)

    Carlos J. Chernicoff

    2013-01-01

    Combining geological and isotope data, as well as geophysical models, we identify the Yaminué Complex within the La Esperanza-Yaminué crustal block flanked by two other, distinct crustal blocks: the Eastern block which forms part of the Patagonia terrane sensu stricto, located in the eastern Patagonian region, and the Western block forming part of the Southern Patagonia terrane. Their origins and timing of amalgamation to form the Patagonia composite terrane are also discussed.

  11. Recognition of the Kaweka Terrane in northern South Island, New Zealand : preliminary evidence from Rb-Sr metamorphic and U-Pb detrital zircon ages

    International Nuclear Information System (INIS)

    Adams, C.J.; Mortimer, N.; Campbell, H.J.; Griffin, W.L.

    2011-01-01

    Detrital zircon U-Pb ages and Rb-Sr metamorphic ages from low-grade Torlesse Supergroup metasedimentary rocks from North Canterbury and Marlborough provide preliminary evidence for a continuation of the Kaweka Terrane of the central North Island into the Torlesse Composite Terrane of the South Island. This would extend from the south side of the Wairau Fault in the upper Wairau River valley southwards to the Lake Tennyson and Lake Sumner areas, and as far as Hawarden. Rb-Sr ages indicate Jurassic metamorphism, 170±24 Ma, with initial 87 Sr/ 86 Sr ratios at that time 0.7073 ± 0.0007 i.e. similar to their North Island counterparts. These Kaweka Terrane rocks have detrital zircon ages that follow the distinctive pattern of the Torlesse rocks in general, i.e. substantial (>30%) Permian-Triassic and Precambrian-Early Palaeozoic groupings, but they also have minor youngest age components c. 175-165 Ma which constrain a maximum Early-Middle Jurassic depositional age. In detail, significant, older zircon components are Late Permian-Early Triassic (260-240 Ma) and Late Triassic (220-210 Ma), but the Precambrian-Early Palaeozoic detrital zircon ages are more scattered. The Kaweka Terrane thus forms a linear belt (c. 500 km) along the length of the Torlesse Composite Terrane in both North and South Islands. In the South Island it coincides with the Esk Head Belt, i.e. east of the Rakaia Terrane (Triassic-Late Permian) and west of the Pahau Terrane (Early Cretaceous-Late Jurassic). (author). 61 refs., 4 figs., 2 tabs.

  12. Park Volcanics, Murihiku Terrane, New Zealand : petrology, petrochemistry, and tectonic significance

    International Nuclear Information System (INIS)

    Coombs, D.S.; Cook, N.D.J.; Kawachi, Y.; Johnstone, R.D.; Gibson, I.L.

    1996-01-01

    The Late Triassic to Early Jurassic Park Volcanics Group comprises minor shallow intrusive and extrusive bodies emplaced during mainly marine sedimentation of the Murihiku Terrane, southern New Zealand. Gowan Andesite in western Southland and Glenham Porphyry andesites in eastern Southland are high-K andesites. Glassy examples have commonly lost K during alteration. Orthoclase contents of Or 3.6-3.7 in plagioclase phenocrysts at An 50 confirm the high-K nature of the melts at the time of phenocryst crystallisation. The Gowan andesites have higher Fe/Mg than the Glenham and related differences in minor element chemistry suggesting lower ∫O 2 during fractionation of the parent magma. Pinney Volcanics in western Southland are mostly high-K trachydacites but, like Glenham Porphyry, include minor rhyolite. Barnicoat Andesite in the Nelson area is medium-K olivine andesite, marginally tholeiitic in terms of its FeO*/MgO versus SiO 2 behaviour, but otherwise is typically calc-alkaline, as are the Gowan, Glenham, and Pinney. Analyses of pyroxenes (augites, orthopyroxenes, reaction rim and groundmass pigeonites) reveal xenocrysts recording an early stage of magma fractionation, slight iron enrichment in the andesite stage, and lowered Fe/Mg and increased Ca contents in augites of the most felsic rocks. Titanian tschermakite and titanian magnesio-tschermakite of deep-seated origin participated in fractionation leading to the Pinney Volcanics, and magnesio-hornblende, edenite, and biotite crystallised as minor late stage minerals following high-level emplacement of Gowan Andesite and siliceous Glenham Porphyry members. Low 87 Sr/ 86 Sr ratios (c. 0.7034-0.7037), REE and multi-element distribution patterns, and the mineralogical features collectively suggest fractionation of the andesites from parental basalt originating in an enriched mantle wedge above a subduction zone, with minimal contamination by continental crust. High-K andesites appear to be unknown in clearly

  13. Evolution of the Archean continental crust in the nucleus of the Yangtze block: Evidence from geochemistry of 3.0 Ga TTG gneisses in the Kongling high-grade metamorphic terrane, South China

    Science.gov (United States)

    Qiu, Xiao-Fei; Ling, Wen-Li; Liu, Xiao-Ming; Lu, Shan-Song; Jiang, Tuo; Wei, Yun-Xu; Peng, Lian-Hong; Tan, Juan-Juan

    2018-04-01

    Archean Tonalite-Trondhjemite-Granodiorite (TTG) rocks are scattered within the Kongling high-grade metamorphic terrane (KHMT) in the northern South China block. A comprehensive geochronological and geochemical study is carried out on the Taoyuan granitic gneisses, a newly recognized TTG suite in the northwestern KHMT. This suite has long been regarded as a Mesoproterozoic magmatic pluton, but U-Pb zircon ages of 2994 ± 22 Ma and 2970 ± 15 Ma are obtained by LA-ICP-MS method in this study. The Taoyuan gneiss suite is trondhjemitic in composition, and has high SiO2 (67.80-74.93 wt.%), Na2O (5.11-5.81 wt.%) contents with Na2O/K2O ratios greater than unity, and low Ni (2.56-7.61 ppm), Cr (1.26-7.67 ppm), Yb (0.32-0.82 ppm) and Y (4.48-11.5 ppm) contents. Plots show large variation in La/Yb and Sr/Y ratios and pronounced depletion in Nb, Ta and Ti in the primitive mantle-normalized spiderdiagram. The gneiss suite also displays two-stage Nd model ages close to its crystallization age with corresponding εNd(t) values of -2.5 to +3.5. It is thus suggested that the Taoyuan gneisses, in fact, is part of the Archean Kongling basement complex. Geochemical evidence implies that the TTG rocks may be derived from partial melting of subducted oceanic crust from a garnetiferous amphibolite source with residual assemblage of garnet + amphibole + plagioclase. Our study further indicates that the nucleus of the Yangtze block might experience a juvenile continental crustal growth during Mesoarchean. We also suggest that the Yangtze block may have its own crustal evolutionary history independent from the North China craton and the Tarim block before Paleoproterozoic.

  14. Precambrian Terranes of African affinities in the southeastern part of Brazil and Uruguay

    International Nuclear Information System (INIS)

    Preciozzi, F.; Basei, M.; Siga Junior, H.; Sato, K.; Kaufuss, G.

    2006-01-01

    The interest in correlating terranes at opposite margins of the South Atlantic Ocean reflects a natural curiosity of both researchers who work in the eastern South-America and who study southwestern Africa. On a large scale scenario the geology of this region is characterized by a central portion composed of Neoproterozoic-Cambrian belts (Dom Feliciano, Kao ko, Damara, Gariep, Saldania) having on each side old gneissic-migmatitic terrains on both continents (Luis Alves, Rio de La Plata, Kalahari and Congo). In South America the Neoproterozoic Dom Feliciano Belt (DFB) predominates in the eastern part of the region and is internally organized according to three different crustal segments characterized, from southeast to northwest, by a Granite belt (deformed I-type medium to high calc-alkaline granites and alkaline granitoid rocks; a Schist belt (volcano-sedimentary rocks metamorphosed from green schist to amphibolite facies and intrusive granitoids), and a Fore land basin (anchimetamorphic sedimentary and volcanic rocks), the latter situated between the Schist belt and the Archean-Paleoproterozoic fore land. Despite discontinuously covered by younger sediments, the NS continuity of these three crustal segments is suggested by similar lithotypes, structural characteristics, ages and isotopic signature, as well as by the gravimetric data. The Major Gercino, Cordilheira, and Sierra Ballena shear zones are part of the major NE-SW lineaments that affect all southern Brazilian and Uruguayan Precambrian terrains. They separate the Dom Feliciano Schist Belt (supra crustal rocks of the Brusque-Porongos and Lavalleja groups), to the West, from the granitoids of the Granite belt, to the East. The shear zones are characterized by a regional NE trend and a resultant oblique direction of movement where ductile-brittle structures predominate

  15. Wild Rodent Ectoparasites Collected from Northwestern Iran

    Directory of Open Access Journals (Sweden)

    Zabihollah Zarei

    2017-04-01

    Full Text Available Background: Rodents play an important role as reservoir of some pathogens, and the host of some ectoparasites as well. These ectoparasites can transmit rodents’ pathogens to human or animals. The aim of this study was to assess the distribution and infestation load of ectoparasites on rodents in Meshkin-Shahr District, northwestern Iran.Method: Rodents were captured using baited live traps in spring 2014 from Meshkin-Shahr District and were trans­ferred to the laboratory for identification to the species level. Their ectoparasites were collected, mounted and identi­fied.Results: Three rodent species including Meriones persicus (74%, Mus musculus (16.9% and Cricetulus migrato­rius (9% were identified. Among all rodents, 185 specimens (90.69% were infested with a total of 521 ectopara­sites. Overall, 10 arthropods species were collected, including fleas (97.6%, one mite (1.6% and one louse species (0.6% as follows: Xenopsylla nubica, X. astia, X. buxtoni, X. cheopis, Nosopsyllus fasciatus, N. iranus, Cten­ocephalides felis, Ctenophthalmus rettigismiti, Ornithonyssus sp and one species of genus Polyplax. The most prev­alent ectoparasites species was X. nubica (89%.Conclusion: Nearly all rodent species were infested with Xenopsylla species. Monitoring of ectoparasites on infested rodents is very important for awareness and early warning towards control of arthropod-borne diseases.

  16. Identification of thermotectonics events by 40Ar/39Ar methodology, in Jauru, Pontes e Lacerda and Rio Alegre Terrane - southwest portion of Amazon Craton

    International Nuclear Information System (INIS)

    Paulo, Valeria Guimaraes de

    2005-01-01

    The southwest portion of Amazon Craton, subject of these work, correspond to the southwest region of Mato Grosso State and is inserted on Rio Negro-Juruena, Rondoniana-San Ignacio and Sunsas-Aguapei geochronologic Provinces. This region is surrounded by three big terranes: Jauru, Pontes e Lacerda and Rio Alegre. The main aim of this study is to use the ages of termochronologic events obtained by 40 Ar/ 39 Ar methodology, including data of literature, to contribute with the study of the geotectonic evolution on this region. Twenty samples were analyzed and 40 Ar/ 39 Ar ages found for the Jauru Terrane vary of 1539 ± 3 Ma to 1338 ± 3 Ma, for the Pontes e Lacerda Terrane the interval obtained was of 946,1 ± 0,8 Ma to 890 ± 2 Ma and for Rio Alegre Terrane the ages are between 1407 ± 3 Ma to 1321 ± 2 Ma. U/Pb, Rb/Sr and Sm/Nd data from previous works, together with 40 Ar/ 39 Ar results allowed to obtain cooling average rates to each terrane. The Jauru Terrane units cooling age is equivalent to 1,52 Ga. The cooling average rates found to Alto Jauru Greenstone belt rocks is 2,4 deg C - 1,0 Ma and to Magmatic Arc Cachoeirinha is 10,8 deg C - 1,0 Ma. Stabilization age obtained for Pontes and Lacerda Terrane is about 900 Ma coherent with the cooling age of the Sunsas Aguapei Event (1,0 - 0,9 Ga) and cooling average rates calculate were the lower, equivalent to 1,0 deg C - 1,0 Ma. Cooling age found in Rio Alegre Terrane was 1,35 Ga, possibility correspond to collision age these terrane with Amazonian protoCraton and cooling average rates of 5,0 deg C - 1,0 Ma. Finally, younger age found of 900 Ma, coherent to the Sunsas - Aguapei Event, probably represent the last regional event that affected these rocks, characterizing the stabilization period of the southwest portion of Amazon Craton. (author)

  17. A geologic guide to Wrangell-Saint Elias National Park and Preserve, Alaska; a tectonic collage of northbound terranes

    Science.gov (United States)

    Winkler, Gary R.; with contributions by MacKevett, E. M.; Plafker, George; Richter, D.H.; Rosenkrans, D.S.; Schmoll, H.R.

    2000-01-01

    Wrangell-Saint Elias National Park and Preserve, the largest unit in the U.S. National Park System, encompasses near 13.2 million acres of geological wonderments. This geologic guide presents history of exploration and Earth-science investigation; describes the complex geologic makeup; characterizes the vast college of accretion geologic terranes in this area of Alaska's continental margin; recapitulates the effects of earthquakes, volcanoes, and glaciers; characterizes the copper and gold resources of the parklands; and describes outstanding locales within the park and preserve area. A glossary of geologic terms and a categorized list of additional sources of information complete this report.

  18. Late Cretaceous tectonothermal evolution of the southern Lhasa terrane, South Tibet: Consequence of a Mesozoic Andean-type orogeny

    Science.gov (United States)

    Dong, Xin; Zhang, Ze-ming; Klemd, Reiner; He, Zhen-yu; Tian, Zuo-lin

    2018-04-01

    The Lhasa terrane of the southern Tibetan Plateau participated in a Mesozoic Andean-type orogeny caused by the northward subduction of the Neo-Tethyan oceanic lithosphere. However, metamorphic rocks, which can unravel details of the geodynamic evolution, are rare and only exposed in the south-eastern part of the Lhasa terrane. Therefore, we conducted a detailed petrological, geochemical and U-Pb zircon geochronological study of the late Cretaceous metamorphic rocks and associated gabbros from the Nyemo inlier of the southern Lhasa terrane. The Nyemo metamorphic rocks including gneisses, schists, marbles and calc-silicate rocks, experienced peak amphibolite-facies contact metamorphism under P-T conditions of 3.5-4.0 kbar and 642-657 °C with a very high geothermal gradient of 45-50 °C/km, revealing a distinct deflection from the steady-state geotherm during low-pressure metamorphism. Inherited magmatic zircon cores from the metamorphic rocks yielded protolith ages of 197-194 Ma, while overgrowth zircon rims yielded metamorphic ages of ca. 86 Ma. Whole-rock chemistry and zircon Hf isotopes suggest that the protoliths of the gneisses and schists are andesites and tuffs of the early Jurassic Sangri Group, which were derived from a depleted mantle source of a continental arc affinity. The coeval intimately-associated gabbro (ca. 86 Ma) crystallized under P-T conditions of 3.5-5.3 kbar and 914-970 °C, supplying the heat flux high enough to cause the contact metamorphism of the Sangri Group rock types. We propose that the intrusion of the gabbro and a simultaneous pressure increase of up to 4.0 kbar, which is related to crustal thickening due to crustal overthrusting and the intrusion of mafic material, resulted in the late Cretaceous metamorphism of the early Jurassic Sangri Group during an Andean-type orogeny. Furthermore the Nyemo metamorphic rocks, which have previously been considered to represent slivers of the Precambrian metamorphic basement of the Lhasa terrane

  19. Accretionary history of the Altai-Mongolian terrane: perspectives from granitic zircon U-Pb and Hf-isotope data

    Science.gov (United States)

    Cai, Keda; Sun, Min; Xiao, Wenjiao

    2014-05-01

    The Central Asian Orogenic Belt (CAOB) consists of many tectonic terranes with distinct origin and complicated evolutionary history. Understanding of individual block is crucial to reconstruct the geodynamic history of the gigantic accetionary collage. This study presents zircon U-Pb ages and Hf isotopes for the granitoid rocks in the Russian Altai mountain range (including Gorny Altai, Altai-Mongolian terrane and CTUS suture zone between them), in order to clarify the timing of granitic magmatism, source nature, continental crustal growth and tectonic evolution. Our dating results suggest that granitic magmatism of the Russian Altai mountain range occurred in three major episodes including 445~429 Ma, 410~360 Ma and ~241 Ma. Most of the zircons within the Paleozoic granitoids present comparable positive ɛHf(t) values and Neoproterozoic crustal model ages, which favor the interpretation that the juvenile crustal materials produced in the early stage of CAOB were probably dominant sources for the Paleozoic magmatism in the region. The inference is also supported by widespread occurrence of short-lived juvenile materials including ophiolites, seamount relics and arc assemblages in the north CAOB. Consequently, the Paleozoic massive granitic rocks maybe not represent continental crustal growth at the time when they were emplaced, but rather record reworking of relatively juvenile Proterozoic crustal rocks although mantle-derived mafic magma was possibly involved to sever as heat engine during granitic magma generation. The Early Triassic granitic intrusion may be product in an intra-plate environment, as the case of same type rocks in the adjacent areas. The positive ɛHf(t) values (1.81~7.47) and corresponding Hf model ages (0.80~1.16 Ga) together with evidence of petrology are consistent with the interpretation that the parental magma of the Triassic granitic intrusion was produced from enriched mantle-derived sources under an usually high temperature condition

  20. Continuation, south of Oaxaca City (southern Mexico) of the Oaxaca-Juarez terrane boundary and of the Oaxaca Fault. Based in MT, gravity and magnetic studies

    Science.gov (United States)

    Campos-Enriquez, J. O.; Corbo, F.; Arzate-Flores, J.; Belmonte-Jimenez, S.; Arango-Galván, C.

    2010-12-01

    The Oaxaca Fault represents Tertiary extensional reactivation of the Juarez shear zone constituting the boundary-suture between the Oaxaca and Juarez terranes (southern Mexico). South of Oaxaca City, the fault trace disappears and there are not clear evidences for its southward continuation at depth. The crust in southern México has been studied through seismic refraction, and seismological and magnetotelluric (MT) studies. The refraction studies did not image the Oaxaca Fault. However, previous regional MT studies suggest that the Oaxaca-Juarez terrane boundary lies to the east of the Zaachila and Mitla sub-basins, which implies sinistral displacement along the Donaji Fault. Campos-Enriquez et al. (2009) established the shallow structure of the Oaxaca-Juarez terrane boundary based in detailed gravity and magnetic studies. This study enabled: 1) to establish the shallow structure of the composite depression comprising three N-S sub-basins: the northern Etla and southern Zaachila sub-basins separated by the Atzompa sub-basin. According to the Oaxaca-Juarez terrane boundary is displaced sinistrally ca. 20 km along the E-W Donají Fault, which defines the northern boundary of the Zaachila sub-basin. At the same time,, the Oaxaca Fault may either continue unbroken southwards along the western margin of a horst in the Zaachila sub-basin or be offset along with the terrane boundary. This model implies that originally the suture was continuous south of the Donaji Fault. A constraint for the accreation of the Oaxaca and Juarez terranes. Thirty MT soundings were done in the area of the Central Valleys, Oaxaca City (southern Mexico). In particular we wanted to image the possible southward continuation of the Oaxaca Fault. 22 Mt sounding are located along two NE-SW profiles to the northern and to the south of the City of Oaxaca. To the north of Oaxaca City, the electrical resistivity distribution obtained show a clear discontinuity across the superficial trace of the Oaxaca

  1. Environmental security: The problems of Northwestern Russia

    International Nuclear Information System (INIS)

    Yablokov, A.V.

    1999-01-01

    The review of main existing environmental problems of North-West Russia covers the radioactive pollution, atmospheric pollution, destroying of the tundra and forest ecosystems, inland and water pollution, consequences of space activities. This region includes: Karelia and Komi republics; Yamalo-Nenetzk autonomous region; Murmansk; Leningrad and Vologda regions; White Sea; Southern and eastern parts of Barents Sea; eastern part of Kara Sea; and eastern part of the Baltic (Finnish Bay). The environmental situation in northwestern Russia is extremely unsafe. The fundamental reason for this situation is Soviet over-militarization in the past. There is an urgent need now to tackle the international environmental security in the Arctic and Scandinavian regions at least in two fields: 1. The existing radioactive pollution (mostly connected with military activities), and even more dangerous - the potential radioactive pollution of the Arctic and Scandinavia. 2. Atmospheric pollution (long distance transportation of pollutant, mostly sulphur dioxide and heavy metals, from melting factories on Kola Peninsula). Several other problems relating to the environmental security of the region (among them deforestation, oil/gas pollution of the ocean, development of the diamond industry) need international attention in the nearest future. It is unrealistic to think that Russia alone can overcome these long-standing problems in the foreseeable future: we need international support for this. But foreign money for solving our environmental problems is not the solution, firstly, because for environmental restoration and recovery Russia needs much more than the international community can allocate; secondly, because there is much money inside Russia (every month, during 1993-1996, up to two billions US dollars were flowing out from Russia to western banks). To utilize this money in a proper way, we drastically need international help to awaken the Russian public environmental awareness

  2. Comparison of Conventional, Trace Element, and Pseudosection Thermobarometry in UHP Eclogite, North Qaidam Terrane, Western China

    Science.gov (United States)

    Mattinson, C. G.; Regel, M. E.; Zhang, J.

    2014-12-01

    In the southeastern North Qaidam terrane, near Dulan, felsic host gneisses enclose minor eclogite lenses. A small (~3°C/km) increase in temperatures to the west based on Zr-in-Rt thermometry is supported by a textural trend of zoned garnet with prograde mineral inclusions in the west to unzoned garnet with only peak-stage inclusions in the east. A western eclogite sample contains minor Ep and trace Phe in addition to Grt-Omp-Qtz-Rt; a strong foliation is defined by banding of Grt and Omp. Garnet Ca falls significantly from core (Alm44Prp23Grs32) to rim (Alm48Prp27Grs23). Phengite contains 3.34-3.36 Si pfu. Conventional Grt-Omp-Phe thermobarometry yields 23-27 kbar, 660-730°C, and Zr-in-Rt thermometry yields 671 ± 9°C (n = 37). An isochemical phase diagram (pseudosection) for the system NCKFMASHO calculated with PerpleX indicates that garnet Xgrs decreases with increasing P and T, suggesting that observed garnet zoning reflects prograde growth. Garnet rim compositional isopleths intersect at 23-27 kbar, 580-620°C, depending on choice of effective bulk composition and assumed Fe3+/Fetotal. Garnet rims help define the foliation, suggesting that these P-T conditions apply to this deformation. An eastern eclogite sample contains minor Ep and abundant, coarse-grained Phe in addition to Grt-Omp-Qtz-Rt; foliation is weak. Garnet zoning is weak; compositions are Alm41-43Prp26-28Grs29-32. Phengite cores contain 3.48-3.56 Si pfu. Conventional Grt-Omp-Phe thermobarometry yields 32-36 kbar, 700-750°C, and Zr-in-Rt thermometry yields 691 ± 12°C (n = 34). Conventional thermobarometry and pseudosections yield similar peak P-T conditions, but from different mineral compositions: thermobarometry yields peak P from high-Ca Grt, but the pseudosection yields peak P from intermediate-Ca Grt; maximum Ca in Grt is predicted at lower P and T. Pseudosection-based peak Ts are significantly lower than those from Zr-in-Rt and conventional thermometry. Wide isopleth spacing in the

  3. Geology of the Severnaya Zemlya Archipelago and the North Kara Terrane in the Russian high Arctic

    Science.gov (United States)

    Lorenz, Henning; Männik, Peep; Gee, David; Proskurnin, Vasilij

    2008-05-01

    The Severnaya Zemlya Archipelago is located at 80°N near the continental shelf break, between the Kara and Laptev seas. Sedimentary successions of Neoproterozoic and Palaeozoic age dominate the bedrock geology. Together with Northern Tajmyr, Severnaya Zemlya constitutes the main land areas of the North Kara Terrane (NKT), which is inferred here to have been a part of the Timanide margin of Baltica, i.e. an integral part of Baltica at least since the Vendian. Vendian turbidites derived from the Timanide Orogen are inferred to have been deposited on Neoproterozoic greenschist facies, granite-intruded basement. Shallow-water siliclastic deposition in the Early to Mid-Cambrian was followed by highly organic-rich shales in the Late Cambrian and influx of more turbidites. An episode of folding, the Kan’on River deformation, separates these formations from the overlying Tremadocian conglomerates and sandstones. In the Early Ordovician, rift-related magmatic rocks accompanied the deposition of variegated marls, sandstones, carbonates and evaporites. Dark shales and gypsiferous limestones characterise the Mid-Ordovician. Late Ordovician quartz-sandstones mark a hiatus, followed by carbonate rocks that extend up into and through most of the Silurian. The latter give way upwards into Old Red Sandstones, which are inferred to have been deposited in a Caledonian foreland basin. Deformation, reaching the area in the latest Devonian or earliest Carboniferous and referred to as the Severnaya Zemlya episode, is thought to be Caledonian-related. The dominating E-vergent structure was controlled by décollement zones in Ordovician evaporite-bearing strata; detachment folds and thrusts developed in the west and were apparently impeded by a barrier of Ordovician igneous rocks in the east. Below the décollement zones, the Neoproterozoic to Early Ordovician succession was deformed into open to close folds. The exposed strata in the lower structural level have been juxtaposed with

  4. 75 FR 1597 - Western Pacific Crustacean Fisheries; 2010 Northwestern Hawaiian Islands Lobster Harvest Guideline

    Science.gov (United States)

    2010-01-12

    ... Pacific Crustacean Fisheries; 2010 Northwestern Hawaiian Islands Lobster Harvest Guideline AGENCY.... ACTION: Notification of lobster harvest guideline. SUMMARY: NMFS announces that the annual harvest guideline for the commercial lobster fishery in the Northwestern Hawaiian Islands (NWHI) for calendar year...

  5. Constraints of detrital zircon U-Pb ages and Hf isotopes on the provenance of the Triassic Yidun Group and tectonic evolution of the Yidun Terrane, Eastern Tibet

    Science.gov (United States)

    Wang, Bai-Qiu; Wang, Wei; Chen, Wei Terry; Gao, Jian-Feng; Zhao, Xin-Fu; Yan, Dan-Ping; Zhou, Mei-Fu

    2013-05-01

    Eastern Tibet to the west of the Yangtze Block consists of the Yidun and Songpan-Ganzi Terranes, separated by the Ganzi-Litang suture zone. The Yidun Terrane includes the Zhongza Massif to the west, but the eastern part of the Yidun terrane is covered by the Yidun Group extending from the south (Shangri-La region) to the north (Changtai region). The Yidun Group, from the base upward, includes the Lieyi, Qugasi, Tumugou and Lanashan formations, which are mainly composed of volcanic-flysch successions. Based on the ages of volcanic interlayers and plutonic intrusions, depositional ages of the Qugasi and Tumugou formations are considered to be slightly older than 230 Ma and ca. 220-230 Ma respectively, which are prominently older than the previous estimates. The Yidun Group in the Changtai region has two prominent detrital zircon age peaks at 400-480 and 880-980 Ma and a minor peak at 2.45-2.50 Ga. This pattern suggests a detritus source from the Zhongza Massif, which was a micro-continent separated from the western Yangtze Block. In contrast, the Yidun Group in the Shangri-La region has various zircon age spectra among different formations. The Qugasi Formation in this region has detrital zircon age patterns similar to the Yidun Group in the Changtai region. However, the overlying Tumugou Formation shows distinct age peaks at Triassic (220-240 Ma), Neoproterozoic (~ 720-880 Ma), and Paleoproterozoic (~ 1.75-1.90 Ga). This age pattern is similar to that of the Xikang Group of the Songpan-Ganzi Terrane to the east. The detrital zircon age difference between the Qugasi and Tumugou formations in this region indicates a transition of sedimentary sources from the Zhongza Massif to locally distributed Triassic magmatic rocks at ~ 230 Ma. It is thus suggested that the Songpan-Ganzi Terrane may have been connected to or collided with the southern part of the Yidun Terrane during the Late Triassic, whereas the Songpan-Ganzi Terrane and the northern part of the Yidun Terrane

  6. 40Ar/39Ar incremental-release ages of biotite from a progressively remetamorphosed Archean basement terrane in southwestern Labrador

    International Nuclear Information System (INIS)

    Dallmeyer, R.D.

    1982-01-01

    Gneisses within Archean basement terrane adjacent to the southwestern portion of the Labrador Trough were variably retrograded during a regional metamorphism of Grenville age (ca. 1000 Ma). Bioties from non-retrograded segments of the gneiss terrane record 40 Ar/ 39 Ar plateau and isochron ages which date times of cooling following an episode of the Kenoran orogeny (2376-2391 Ma). A suite of gneiss samples displaying varying degrees of retrograde alteration was collected across the Grenville metamorphic gradient. Bioties in these samples show no petrographic evidence of retrograde alteration, however they do record internally discordant 40 Ar/ 39 Ar age spectra. Although the extent of internal discordance is variable, the overall character of the release patterns is similar with younger apparent ages recorded in intermediate-temperature gas fractions. The total-gas dates range from 2257+-27 Ma (northwest) to 1751+-23 Ma (southeast), suggesting that variable quantities of radiogenic argon were lost from the Archean biotites during Grenville metamorphism. The 'saddle-shaped' nature of the discordant spectra indicates that argon loss was not accomplished through single-stage, volume diffusion processes. (orig./ME)

  7. Geophysical interpretation of the gneiss terrane of northern Washington and southern British Columbia, and its implications for uranium exploration

    Science.gov (United States)

    Cady, John W.; Fox, Kenneth F.

    1984-01-01

    The Omineca crystalline belt of northeastern Washington and southern British Columbia has a regional Bouguer gravity high, and individual gneiss domes within the terrane are marked by local gravity highs. Models of crustal structure that satisfy the limited available seismic-refraction data and explain the gravity high over the gneiss terrane permit the hypothesis that the core metamorphic complexes are the surface expression of a zone of dense infrastructure that makes up the upper 20 km (kilometers) of the crust within the crystalline belt. The Omineca crystalline belt is characterized regionally by low aeromagnetic relief. The gneiss domes and biotite- and biotite-muscovite granites are generally marked by low magnetic relief, whereas hornblende-biotite granites often cause magnetic highs. Exceptional magnetic highs mark zones of magnetic rock within the biotite- and biotite-muscovite granites and the gneiss domes; these areas are worthy of study, both to determine the origin and disposition of the magnetite and to explore the possible existence of uraniferous magnetite deposits.

  8. The Ellsworth terrane, coastal Maine: Geochronology, geochemistry, and Nd-Pb isotopic composition - Implications for the rifting of Ganderia

    Science.gov (United States)

    Schulz, K.J.; Stewart, D.B.; Tucker, R.D.; Pollock, J.C.; Ayuso, R.A.

    2008-01-01

    The Ellsworth terrane is one of a number of fault-bounded blocks that occur along the eastern margin of Ganderia, the western-most of the peri-Gondwanan domains in the northern Appalachians that were accreted to Laurentia in the Paleozoic. Geologic relations, detrital zircon ages, and basalt geochemistry suggest that the Ellsworth terrane is part of Ganderia and not an exotic terrane. In the Penobscot Bay area of coastal Maine, the Ellsworth terrane is dominantly composed of bimodal basalt-rhyolite volcanic sequences of the Ellsworth Schist and unconformably overlying Castine Volcanics. We use new U-Pb zircon geochronology, geochemistry, and Nd and Pb isotopes for these volcanic sequences to constrain the petrogenetic history and paleotectonic setting of the Ellsworth terrane and its relationship with Ganderia. U-Pb zircon geochronology for rhyolites indicates that both the Ellsworth Schist (508.6 ?? 0.8 Ma) and overlying Castine Volcanics (503.5 ?? 2.5 Ma) are Middle Cambrian in age. Two tholefitic basalt types are recognized. Type Tb-1 basalt, present as pillowed and massive lava flows and as sills in both units, has depleted La and Ce ([La/Nd]N = 0.53-0.87) values, flat heavy rare earth element (REE) values, and no positive Th or negative Ta anomalies on primitive mantle-normalized diagrams. In contrast, type Th-2 basalt, present only in the Castine Volcanics, has stightly enriched LREE ([La/Yb]N = 1.42-2.92) values and no Th or Th anomalies. Both basalt types have strongly positive ??Nd (500) values (Th-1 = +7.9-+8.6; Th-2 = +5.6-+7.0) and relatively enriched Pb isotopic compositions (206Ph/204Pb = 18.037-19.784; 207/204Pb = 15.531-15.660; 2088Pb/204Pb = 37.810-38.817). The basalts have compositions transitional between recent normal and enriched mid-ocean-ridge basalt, and they were probably derived by partial melting of compositionatly heterogeneous asthenosphenc mantle. Two types of rhyolite also are present. Type R-1 rhyolite, which mostly occurs as tuffs

  9. North by Northwestern: initial experience with PACS at Northwestern Memorial Hospital

    Science.gov (United States)

    Channin, David S.; Hawkins, Rodney C.; Enzmann, Dieter R.

    2000-05-01

    This paper describes the initial phases and configuration of the Picture Archive and Communication System (PACS) deployed at Northwestern Memorial Hospital. The primary goals of the project were to improve service to patients, improve service to referring physicians, and improve the process of radiology. Secondary goals were to enhance the academic mission, and modernize institutional information systems. The system consists of a large number of heterogeneous imaging modalities sending imaging studies via DICOM to a GE medical Systems PathSpeed PACS. The radiology department workflow is briefly described. The system is currently storing approximately 140,000 studies and over 5 million images, growing by approximately 600 studies and 25,000 images per day. Data reflecting use of the short term and long term storage is provided.

  10. Reconnaissance geologic mapping of a portion of the rain‐forest‐covered Guiana Shield, Northwestern Brazil, using SIR-B and digital aeromagnetic data

    Science.gov (United States)

    Pellon de Miranda, Fernando; McCafferty, Anne E.; Taranik, James V.

    1994-01-01

    This paper documents the result of an integrated analysis of spaceborne radar (SIR-B) and digital aeromagnetic data carried out in the heavily forested Guiana Shield. The objective of the research is to interpret the geophysical data base to its limit to produce a reconnaissance geologic map as an aid to ground work planning in a worst‐case setting. Linear geomorphic features were identified based on the interpretation of the SIR-B image. Digital manipulation of aeromagnetic data allowed the development of a color‐shaded relief map of reduced‐to‐pole magnetic anomalies, a terrace‐magnetization map, and a map showing the location of maximum values of the horizontal component of the pseudogravity gradient (magnetization boundary lines). The resultant end product was a reconnaissance geologic map where broad terrane categories were delineated and geologic faults with both topographic and magnetic expression were defined. The availability of global spaceborne radar coverage in the 1990s and the large number of existing digital aeromagnetic surveys in northwestern Brazil indicate that this approach can be potentially useful for reconnaissance geologic mapping elsewhere in the Guiana Shield.

  11. Capturing Qualitative Data: Northwestern University Special Libraries' Acknowledgments Database

    Science.gov (United States)

    Stigberg, Sara; Guittar, Michelle; Morse, Geoffrey

    2015-01-01

    Assessment and supporting data have become of increasing interest in librarianship. In this paper, we describe the development and implementation of the Northwestern University Library Acknowledgments Database tool, which gathers and documents qualitative data, as well as its component reporting function. This collaborative project and resulting…

  12. Spotted owl roost and nest site selection in northwestern California

    Science.gov (United States)

    J.A. Blakesley; A.B. Franklin; R.J. Gutierrez

    1992-01-01

    We directly observed roost and nest site selection in a population of northern spotted owls (Strix occidentalis caurina) in northwestern California during 1985-89. Because of potential biases caused by use of radio telemetry in previous studies, we examined habitat use relative to habitat availability at a level not previously reported for spotted...

  13. Beak deformities in Northwestern Crows: Evidence of a multispecies epizootic

    Science.gov (United States)

    Van Hemert, Caroline; Handel, Colleen M.

    2010-01-01

    Beak abnormalities are rare among adult birds and, typically, are not widespread in a given population, within a region, or across multiple species. A high concentration of beak deformities was recently documented in Black-capped Chickadees (Poecile atricapillus) and other resident avian species in Alaska. We describe a parallel condition in Northwestern Crows (Corvus caurinus) that signals the emergence of a multispecies epizootic. On the basis of 186 Northwestern Crows captured at six sites in Alaska during 2007 and 2008, we estimated the prevalence of beak deformities in adults to be 16.9 ± 5.3%, the highest rate of gross deformities ever recorded in a wild bird population. Prevalence varied among sites and was as high as 36% on the Kenai Peninsula, which suggests possible epizootic clusters. We also documented beak abnormalities in an additional 148 Northwestern Crows in south-central and southeastern Alaska and in 64 crows near Vancouver, British Columbia, and Puget Sound, Washington, a region where both Northwestern Crows and American Crows (C. brachyrhynchos) occur. The increase in frequency and distribution of crows observed with abnormal beaks throughout the Pacific Northwest since the late 1990s indicates a geographic expansion of this problem. Affected crows exhibited elongated and often crossed beaks that were morphologically similar to deformities documented in Black-capped Chickadees and other species in Alaska over approximately the same period. Additional research is needed to determine the etiology and potential adverse effects on bird populations affected by this disorder.

  14. The Dorstenia species (Moraceae) of north-western tropical America

    NARCIS (Netherlands)

    Berg, C.C.; Leeuwen, van R.W.J.

    1982-01-01

    Four new species of Dorstenia are described: D. panamensis C.C. Berg, D. boliviana C.C. Berg, D. peruviana C.C. Berg, and D. belizensis C.C. Berg. A list of and a key to the 21 Dorstenia species distinguished in north-western tropical America are presented, together with synonyms and distributions.

  15. Upland forest vegetation of the Ozark Mountains in Northwestern Arkansas

    Science.gov (United States)

    Steven L. Stephenson; Harold S. Adams; Cynthia D. Huebner

    2007-01-01

    Quantitative data on structure and composition of all strata of vegetation were collected from 20 study sites in the Boston Mountains Subsection of the Ozark Mountains of northwestern Arkansas in June 2004. All study sites were located at upper slope or ridgetop positions and occurred at elevations > 457 m. Oaks (Quercus spp.) were dominants in...

  16. GPR Imaging of Fault Related Folds in a Gold-Bearing Metasedimentary Sequence, Carolina Terrane, Southern Appalachian Mountains

    Science.gov (United States)

    Diemer, J. A.; Bobyarchick, A. R.

    2015-12-01

    The Carolina terrane comprises Ediacaran to earliest Paleozoic mixed magmatic and sedimentary assemblages in the central and eastern Piedmont of the Southern Appalachian Mountains. The terrane was primarily deformed during the Late Ordovician Cherokee orogeny, that reached greenschist facies metamorphism. The Albemarle arc, a younger component of the Carolina terrane, contains volcanogenic metasedimentary rocks with intercalated mainly rhyolitic volcanic rocks. Regional inclined to overturned folds with axial planar cleavage verge southeast. At mesoscopic scales (exposures of a few square meters), folds sympathetic with regional folds are attenuated or truncated by ductile shear zones or contractional faults. Shear and fault zones are most abundant near highly silicified strataform zones in metagraywacke of the Tillery Formation; these zones are also auriferous. GPR profiles were collected across strike of two silicified, gold-bearing zones and enclosing metagraywacke to characterize the scale and extent of folding in the vicinity of ore horizons. Several GSSI SIR-3000 / 100 MHz monostatic GPR profiles were collected in profiles up to 260 meters long. In pre-migration lines processed for time zero and background removal, several clusters of shallow, rolling sigmoidal reflectors appeared separated by sets of parallel, northwest-dipping reflective discontinuities. These features are inferred to be reverse faults carrying contractional folds. After migration with an average velocity of 0.105 m/ns, vertical heights of the inferred folds became attenuated but not removed, and contractional fault reflections remained prominent. After migration, a highly convex-up cluster of reflections initially assumed to be a fold culmination resolved to an elliptical patch of high amplitudes. The patch is likely an undisclosed shaft or covered trench left by earlier gold prospecting. In this survey, useful detail appeared to a depth of 7.5 meters, and only a few gently inclined

  17. Cenozoic mantle composition evolution of southern Tibet indicated by Paleocene ( 64 Ma) pseudoleucite phonolitic rocks in central Lhasa terrane

    Science.gov (United States)

    Qi, Yue; Gou, Guo-Ning; Wang, Qiang; Wyman, Derek A.; Jiang, Zi-Qi; Li, Qiu-Li; Zhang, Le

    2018-03-01

    The question of whether continental subduction processes in collisional orogenic belts can trigger wide-spread mantle metesomatism and crustal material recycling remains unresolved. Miocene (25-8 Ma) ultrapotassic rocks in southern Tibet are the only mantle-derived magmatic rocks emplaced after the collision between India and Asia and they have been linked to the onset of east-west extensional stresses as the surface uplift of the Tibetan Plateau reached near-maximum elevation. However, their petrogenesis remains highly controversial, particularly the issue of whether their extremely enriched Sr-Nd isotopic characteristics were related to metasomatism derived from subducted Indian continental materials during the Cenozoic. Here we report on a Paleocene silicate-unsaturated, pseudoleucite phonolitic dike, in the Rongniduo area of central Lhasa terrane. In-situ SIMS (secondary ion mass spectrometry) apatite U-Pb age indicates the dike was generated at 64.1 ± 4.2 Ma, which slightly predates the age of initial India and Asia collision (about 55-50 Ma). This is the oldest age yet reported for ultrapotassic rocks in southern Tibet. Samples from this dike have distinctly more depleted Sr-Nd (whole rock: (87Sr/86Sr)i = 0.7064 to 0.7062, εNd(t) = - 1.5 to 0.4; in situ apitite: (87Sr/86Sr)i = 0.7059 to 0.7060, εNd(t) = - 2.0 to 0.4) isotopic compositions, than those of Miocene (25-8 Ma) ultrapotassic rocks in the central Lhasa terrane ((87Sr/86Sr)i = 0.7106 to 0.7399, εNd(t) = - 10.6 to - 18.5). Our new data provides important constraints on pre-collisional mantle characteristics beneath the Lhasa terrane. We suggest that these 64 Ma pseudoleucite phonolitic rocks were derived from the enriched lithospheric mantle metasomatized by subducted Tethyan oceanic materials in response to Neo-Tethyan slab roll-back. As a consequence, the younger Miocene ultrapotassic rocks, which display different geochemical compositions from the pre-collisional ultrapotassic rocks, were most

  18. Geochronological and geochemical constraints on the origin of the Yunzhug ophiolite in the Shiquanhe-Yunzhug-Namu Tso ophiolite belt, Lhasa Terrane, Tibetan Plateau

    Science.gov (United States)

    Zeng, Yun-Chuan; Xu, Ji-Feng; Chen, Jian-Lin; Wang, Bao-Di; Kang, Zhi-Qiang; Huang, Feng

    2018-02-01

    The formation of the Shiquanhe-Yunzhug-Namu Tso ophiolite mélange zone (SNMZ) within the Lhasa Terrane, Tibetan Plateau, is key to understanding the Mesozoic tectonic evolution of this terrane, which remains controversial. We show that the Yunzhug ophiolite in the central segment of the SNMZ formed at 150 Ma, based on U-Pb dating of zircons from a gabbroic sample in a well-developed sheeted dike complex. Geochemically, these mafic rocks are dominated by E-MORB-type compositions, along with minor amounts of rocks with P-MORB-type compositions. The samples also exhibit high εNd(t) values and lack negative Nb and Ta anomalies. Data for all the samples plot within the MORB array on a Th/Yb-Nb/Yb diagram. Therefore, these mafic rocks most likely formed in either a slow spreading oceanic setting or an embryonic ocean, and not in a back-arc basin as has been previously assumed. Taking into account the regional geology, we propose that the Yunzhug ophiolite is part of a distinct ophiolitic belt and represents material formed in an embryonic ocean within the Lhasa Terrane, which provides new insights into the Jurassic tectonic evolution of the Lhasa Terrane.

  19. Grenville age of basement rocks in Cape May NJ well: New evidence for Laurentian crust in U.S. Atlantic Coastal Plain basement Chesapeake terrane

    Science.gov (United States)

    Sheridan, R.E.; Maguire, T.J.; Feigenson, M.D.; Patino, L.C.; Volkert, R.A.

    1999-01-01

    The Chesapeake terrane of the U.S. mid-Atlantic Coastal Plain basement is bounded on the northwest by the Salisbury positive gravity and magnetic anomaly and extends to the southeast as far as the Atlantic coast. It underlies the Coastal Plain of Virginia, Maryland, Delaware and southern New Jersey. Rubidium/Strontium dating of the Chesapeake terrane basement yields an age of 1.025 ?? 0.036 Ga. This age is typical of Grenville province rocks of the Middle to Late Proterozoic Laurentian continent. The basement lithologies are similar to some exposed Grenville-age rocks of the Appalachians. The TiO2 and Zr/P2O5 composition of the metagabbro from the Chesapeake terrane basement is overlapped by those of the Proterozoic mafic dikes in the New Jersey Highlands. These new findings support the interpretation that Laurentian basement extends southeast as far as the continental shelf in the U.S. mid-Atlantic region. The subcrop of Laurentian crust under the mid-Atlantic Coastal Plain implies unroofing by erosion of the younger Carolina (Avalon) supracrustal terrane. Dextral-transpression fault duplexes may have caused excessive uplift in the Salisbury Embayment area during the Alleghanian orogeny. This extra uplift in the Salisbury area may have caused the subsequent greater subsidence of the Coastal Plain basement in the embayment.

  20. U-Pb detrital zircon geochronology from the basement of the Central Qilian Terrane: implications for tectonic evolution of northeastern Tibetan Plateau

    Science.gov (United States)

    Liu, Changfeng; Wu, Chen; Zhou, Zhiguang; Yan, Zhu; Jiang, Tian; Song, Zhijie; Liu, Wencan; Yang, Xin; Zhang, Hongyuan

    2018-03-01

    The Tuolai Group dominates the Central Qilian Terrane, and there are different opinions on the age and tectonic attribute of the Tuolai Group. Based on large-scale geologic mapping and zircon dating, the Tuolai Group is divided into four parts: metamorphic supracrustal rocks, Neoproterozoic acid intrusive rocks, early-middle Ordovician acid intrusive rocks and middle Ordovician basic intrusive rocks. The metamorphic supracrustal rocks are the redefined Tuolai complex-group and include gneiss and schist assemblage by faulting contact. Zircon U-Pb LA-MC-ICP-MS dating was conducted on these samples of gneiss and migmatite from the gneiss assemblage, quartzite, two-mica schist and slate from the schist assemblage. The five detrital samples possess similar age spectra; have detrital zircon U-Pb main peak ages of 1.7 Ga with youngest U-Pb ages of 1150 Ma. They are intruded by Neoproterozoic acid intrusive rocks. Therefore, the Tuolai Group belonging to late Mesoproterozoic and early Neoproterozoic. With this caveat in mind, we believe that U-Pb detrital zircon dating, together with the geologic constraints obtained from this study and early work in the neighboring regions. We suggest that the formation age of the entire crystalline basement rocks of metasedimentary sequence from the Central Qilian Terrane should be constrained between the Late Mesoproterozoic and the Late Neoproterozoic, but not the previous Paleoproterozoic. The basement of the Central Qilian Terrane contains the typical Grenville ages, which indicates the Centre Qilian Terrane have been experienced the Grenville orogeny event.

  1. Geochronology and geochemistry of the Early Jurassic Yeba Formation volcanic rocks in southern Tibet: Initiation of back-arc rifting and crustal accretion in the southern Lhasa Terrane

    Science.gov (United States)

    Wei, Youqing; Zhao, Zhidan; Niu, Yaoling; Zhu, Di-Cheng; Liu, Dong; Wang, Qing; Hou, Zengqian; Mo, Xuanxue; Wei, Jiuchuan

    2017-05-01

    Understanding the geological history of the Lhasa Terrane prior to the India-Asia collision ( 55 ± 10 Ma) is essential for improved models of syn-collisional and post-collisional processes in the southern Lhasa Terrane. The Miocene ( 18-10 Ma) adakitic magmatism with economically significant porphyry-type mineralization has been interpreted as resulting from partial melting of the Jurassic juvenile crust, but how this juvenile crust was accreted remains poorly known. For this reason, we carried out a detailed study on the volcanic rocks of the Yeba Formation (YF) with the results offering insights into the ways in which the juvenile crust may be accreted in the southern Lhasa Terrane in the Jurassic. The YF volcanic rocks are compositionally bimodal, comprising basalt/basaltic andesite and dacite/rhyolite dated at 183-174 Ma. All these rocks have an arc-like signature with enriched large ion lithophile elements (LILEs; e.g., Rb, Ba and U) and light rare earth elements (LREEs) and depleted high field strength elements (HFSEs; e.g., Nb, Ta, Ti). They also have depleted whole-rock Sr-Nd and zircon Hf isotopic compositions, pointing to significant mantle isotopic contributions. Modeling results of trace elements and isotopes are most consistent with the basalts being derived from a mantle source metasomatized by varying enrichment of subduction components. The silicic volcanic rocks show the characteristics of transitional I-S type granites, and are best interpreted as resulting from re-melting of a mixed source of juvenile amphibole-rich lower crust with reworked crustal materials resembling metagraywackes. Importantly, our results indicate northward Neo-Tethyan seafloor subduction beneath the Lhasa Terrane with the YF volcanism being caused by the initiation of back-arc rifting. The back-arc setting is a likely site for juvenile crustal accretion in the southern Lhasa Terrane.

  2. Linking the southern West Junggar terrane to the Yili Block: Insights from the oldest accretionary complexes in West Junggar, NW China

    Science.gov (United States)

    Ren, Rong; Han, Bao-Fu; Guan, Shu-Wei; Liu, Bo; Wang, Zeng-Zhen

    2018-06-01

    West Junggar is known to tectonically correlate with East Kazakhstan; however, the tectonic link of the southern West Junggar terrane to adjacent regions still remains uncertain. Here, we examined the oldest accretionary complexes, thus constraining its tectonic evolution and link during the Early-Middle Paleozoic. They have contrasting lithologic, geochemical, and geochronological features and thus, provenances and tectonic settings. The Laba Unit was derived from the Late Ordovician-Early Devonian continental arc system (peaking at 450-420 Ma) with Precambrian substrate, which formed as early as the Early Devonian and metamorphosed during the Permian; however, the Kekeshayi Unit was accumulated in an intra-oceanic arc setting, and includes the pre-Late Silurian and Late Silurian subunits with or without Precambrian sources. Integrated with the regional data, the southern West Junggar terrane revealed a tectonic link to the northern Yili Block during the Late Silurian to Early Devonian, as suggested by the comparable Precambrian zircon age spectra between the southern West Junggar terrane and the micro-continents in the southern Kazakhstan Orocline, the proximal accumulation of the Laba Unit in the continental arc atop the Yili Block, and the sudden appearance of Precambrian zircons in the Kekeshayi Unit during the Late Silurian. This link rejects the proposals of the southern West Junggar terrane as an extension of the northern Kazakhstan Orocline and the Middle Paleozoic amalgamation of West Junggar. A new linking model is thus proposed, in which the southern West Junggar terrane first evolved individually, and then collided with the Yili Block to constitute the Kazakhstan continent during the Late Silurian. The independent and contrasting intra-oceanic and continental arcs also support the Paleozoic archipelago-type evolution of the Central Asian Orogenic Belt.

  3. Precambrian Field Camp at the University of Minnesota Duluth - Teaching Skills Applicable to Mapping Glaciated Terranes of the Canadian Shield

    Science.gov (United States)

    Miller, J. D.; Hudak, G. J.; Peterson, D.

    2011-12-01

    Since 2007, the central program of the Precambrian Research Center (PRC) at the University of Minnesota Duluth has been a six-week geology field camp focused on the Precambrian geology of the Canadian Shield. This field camp has two main purposes. First and foremost is to teach students specialized field skills and field mapping techniques that can be utilized to map and interpret Precambrian shield terranes characterized by sparse outcrop and abundant glacial cover. In addition to teaching basic outcrop mapping technique , students are introduced to geophysical surveying (gravity, magnetics), glacial drift prospecting, and drill core logging techniques in several of our geological mapping exercises. These mapping methodologies are particularly applicable to minerals exploration in shield terranes. The second and equally important goal of the PRC field camp is to teach students modern map-making and map production skills. During the fifth and sixth weeks of field camp, students conduct "capstone" mapping projects. These projects encompass one week of detailed bedrock mapping in remote regions of northern Minnesota that have not been mapped in detail (e.g. scales greater than 1:24,000) and a second week of map-making and map generation utilizing geographic information systems (currently ArcGIS10), graphics software packages (Adobe Illustrator CS4), and various imaging software for geophysical and topographic data. Over the past five years, PRC students and faculty have collaboratively published 21 geologic maps through the Precambrian Research Center Map Series. These maps are currently being utilized in a variety of ways by industry, academia, and government for mineral exploration programs, development of undergraduate, graduate, and faculty research projects, and for planning, archeological studies, and public education programs in Minnesota's state parks. Acquisition of specialized Precambrian geological mapping skills and geologic map-making proficiencies has

  4. Petrography and geochemistry of five granitic plutons from south central Uruguay: contribution to the knowledge of the Piedra Alta terrane

    International Nuclear Information System (INIS)

    Preciozzi, F.

    2005-01-01

    Granitoid rocks in south-central Uruguay are largely concentrated in three east-west trending metamorphic belts, known as (from south to north) the Montevideo Belt, the San José Belt and the Arroyo Grande Belt. These belts are separated from one another by intervening bands of gneisses of granitic composition. The whole assemblage, the gneisses as well as the metamorphic belts and their associated granites, collectively constitute the Piedra Alta Terrane. Five of these granite plutons, two from the San José Belt and three from the Arroyo Grande Belt, have been studied in some detail and the chemical composition of 86 samples (major elements as well as a selected suite of trace elements) have been determined. These data, as well as Rb-Sr isotopic data, show that these plutons are typically composite in nature, and that the various units range in age from 1900 Ma to 2500 Ma. The older ages were obtained from the main units of the plutons themselves whereas the younger ages are from late dykes which were emplaced into the plutons and which are clearly not related to them. The plutons are predominantly, but not exclusively, of calc-alkaline affinity and are typically synorogenic whereas the dykes are post-orogenic and are either calc-alkaline or alkaline in composition. These data have been incorporated into a tectonic model for the Piedra Alta Terrane which is considerably different from that heretofore proposed. The essential features of the geological history of the area are: 1) development of an older ''basement'' of granitic gneisses 2) deposition, upon or adjacent to this gneisses basement, of a typical Archean greenstone belt assemblage (no komatiites so far reported) 3) Paleo-proterozoic metamorphism, followed by syn-tectonic to post-tectonic intrusion of the plutonic rocks 4) major tectonic dislocation(s) associated with the Transamazonian orogeny 5) dyke emplacement (post-orogenic to anorogenic) following the Transamazonian orogeny

  5. Tropical storm Irene flood of August 2011 in northwestern Massachusetts

    Science.gov (United States)

    Bent, Gardner C.; Olson, Scott A.; Massey, Andrew J.

    2016-09-02

    A Presidential disaster was declared in northwestern Massachusetts, following flooding from tropical storm Irene on August 28, 2011. During the storm, 3 to 10 inches of rain fell on soils that were susceptible to flash flooding because of wet antecedent conditions. The gage height at one U.S. Geological Survey streamgage rose nearly 20 feet in less than 4 hours because of the combination of saturated soils and intense rainfall. On August 28, 2011, in the Deerfield and Hoosic River Basins in northwestern Massachusetts, new peaks of record were set at six of eight U.S. Geological Survey long-term streamgages with 46 to 100 years of record. Additionally, high-water marks were surveyed and indirect measurements of peak discharge were calculated at two discontinued streamgages in the Deerfield and Hoosic River Basins with 24 and 61 years of record, respectively. This data resulted in new historic peaks of record at the two discontinued streamgages from tropical storm Irene.

  6. Multivariate statistical analysis of precipitation chemistry in Northwestern Spain

    International Nuclear Information System (INIS)

    Prada-Sanchez, J.M.; Garcia-Jurado, I.; Gonzalez-Manteiga, W.; Fiestras-Janeiro, M.G.; Espada-Rios, M.I.; Lucas-Dominguez, T.

    1993-01-01

    149 samples of rainwater were collected in the proximity of a power station in northwestern Spain at three rainwater monitoring stations. The resulting data are analyzed using multivariate statistical techniques. Firstly, the Principal Component Analysis shows that there are three main sources of pollution in the area (a marine source, a rural source and an acid source). The impact from pollution from these sources on the immediate environment of the stations is studied using Factorial Discriminant Analysis. 8 refs., 7 figs., 11 tabs

  7. Multivariate statistical analysis of precipitation chemistry in Northwestern Spain

    Energy Technology Data Exchange (ETDEWEB)

    Prada-Sanchez, J.M.; Garcia-Jurado, I.; Gonzalez-Manteiga, W.; Fiestras-Janeiro, M.G.; Espada-Rios, M.I.; Lucas-Dominguez, T. (University of Santiago, Santiago (Spain). Faculty of Mathematics, Dept. of Statistics and Operations Research)

    1993-07-01

    149 samples of rainwater were collected in the proximity of a power station in northwestern Spain at three rainwater monitoring stations. The resulting data are analyzed using multivariate statistical techniques. Firstly, the Principal Component Analysis shows that there are three main sources of pollution in the area (a marine source, a rural source and an acid source). The impact from pollution from these sources on the immediate environment of the stations is studied using Factorial Discriminant Analysis. 8 refs., 7 figs., 11 tabs.

  8. Deformation of the Northwestern Okhotsk Plate: How is it happening?

    OpenAIRE

    Hindle, D.; Fujita, K.; Mackey, K.

    2009-01-01

    The Eurasia (EU) – North America (NA) plate boundary zone across Northeast Asia still presents many open questions within the plate tectonic paradigm. Constraining the geometry and number of plates or microplates present in the plate boundary zone is especially difficult because of the location of the EU-NA euler pole close to or even upon the EU-NA boundary. One of the major challenges remains the geometry of the Okhotsk plate (OK). whose northwestern portion terminates on ...

  9. Dynamics, patterns and causes of fires in Northwestern Amazonia.

    Science.gov (United States)

    Armenteras, Dolors; Retana, Javier

    2012-01-01

    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.

  10. Food habits of pumas in northwestern Sonora, Mexico

    Science.gov (United States)

    Rosas-Rosas, O. C.; Valdez, R.; Bender, L.C.; Daniel, D.

    2003-01-01

    It is questionable whether food-habits studies of pumas conducted in the southwestern United States can be extrapolated to northwestern Mexico, because of differences in management, distribution, and abundance of wildlife. We determined food habits of pumas (Puma concolor) in the Sonoran Desert of northwestern Sonora, Mexico. Based on studies in the western United States, we hypothesized that desert mule deer (Odocoileus hemionus) were the major food source of pumas in Sonoran Desert habitats of Mexico. The study area supports populations of desert mule deer, white-tailed deer (Odocoileus virginianus), lagomorphs (Lepus spp. and Sylvilagus audubonii), collared peccary (Pecari tajacu), and the largest population (???300 individuals) of desert bighorn sheep (Ovis canadensis) in Sonora. Based on pugmark characteristics, we recorded 3 different adult resident pumas in approximately 90 km2. We analyzed 60 puma fecal samples collected September 1996-November 1998. Primary prey items based on frequency of occurrence and estimated biomass consumed were desert bighorn sheep (40% and 45%, respectively), lagomorphs (33%, 19%), deer (17%, 17%), and collared peccary (15%, 11%). The high percentage of desert bighorn sheep in puma diets may be due to high abundance relative to mule deer, which declined in number during our study. No differences were found in puma diets between seasons (??22=2.4526, P=0.2934). Fluctuations in mule deer populations in northwestern Sonora may influence prey selection by pumas.

  11. Integration of potential and quasipotential geophysical fields and GPR data for delineation of buried karst terranes in complex environments

    Science.gov (United States)

    Eppelbaum, L. V.; Alperovich, L. S.; Zheludev, V.; Ezersky, M.; Al-Zoubi, A.; Levi, E.

    2012-04-01

    Karst is found on particularly soluble rocks, especially limestone, marble, and dolomite (carbonate rocks), but is also developed on gypsum and rock salt. Subsurface carbonate rocks involved in karst groundwater circulation considerably extend the active karst realm, to perhaps 14% of the world's land area (Price, 2009). The phenomenon of the solution weathering of limestone is the most widely known in the world. Active sinkholes growth appears under different industrial constructions, roads, railways, bridges, airports, buildings, etc. Regions with arid and semi-arid climate occupy about 30% of the Earth's land. Subsurface in arid regions is characterized by high variability of physical properties both on lateral and vertical that complicates geophysical survey analysis. Therefore for localization and monitoring of karst terranes effective and reliable geophysical methodologies should be applied. Such advanced methods were developed in microgravity (Eppelbaum et al., 2008; Eppelbaum, 2011b), magnetic (Khesin et al., 1996; Eppelbaum et al., 2000, 2004; Eppelbaum, 2011a), induced polarization (Khesin et al., 1997; Eppelbaum and Khesin, 2002), VLF (Eppelbaum and Khesin, 1992; Eppelbaum and Mishne, 2012), near-surface temperature (Eppelbaum, 2009), self-potential (Khesin et al., 1996; Eppelbaum and Khesin, 2002), and resistivity (Eppelbaum, 1999, 2007a) surveys. Application of some of these methodologies in the western and eastern shores of the Dead Sea area (e.g., Eppelbaum et al., 2008; Ezersky et al., 2010; Al-Zoubi et al., 2011) and in other regions of the world (Eppelbaum, 2007a) has shown their effectiveness. The common procedures for ring structure identification against the noise background and probabilistic-deterministic methods for recognizing the desired targets in complex media are presented in Khesin and Eppelbaum (1997), Eppelbaum et al. (2003), and Eppelbaum (2007b). For integrated analysis of different geophysical fields (including GPR images) intended

  12. The Cannery Formation--Devonian to Early Permian arc-marginal deposits within the Alexander Terrane, Southeastern Alaska

    Science.gov (United States)

    Karl, Susan M.; Layer, Paul W.; Harris, Anita G.; Haeussler, Peter J.; Murchey, Benita L.

    2011-01-01

    cherts on both Admiralty and Kupreanof Islands contain radiolarians as young as Permian, the age of the Cannery Formation is herein extended to Late Devonian through early Permian, to include the early Permian rocks exposed in its type locality. The Cannery Formation is folded and faulted, and its stratigraphic thickness is unknown but inferred to be several hundred meters. The Cannery Formation represents an extended period of marine deposition in moderately deep water, with slow rates of deposition and limited clastic input during Devonian through Pennsylvanian time and increasing argillaceous, volcaniclastic, and bioclastic input during the Permian. The Cannery Formation comprises upper Paleozoic rocks in the Alexander terrane of southeastern Alaska. In the pre-Permian upper Paleozoic, the tectonic setting of the Alexander terrane consisted of two or more evolved oceanic arcs. The lower Permian section is represented by a distinctive suite of rocks in the Alexander terrane, which includes sedimentary and volcanic rocks containing early Permian fossils, metamorphosed rocks with early Permian cooling ages, and intrusive rocks with early Permian cooling ages, that form discrete northwest-trending belts. After restoration of 180 km of dextral displacement of the Chilkat-Chichagof block on the Chatham Strait Fault, these belts consist, from northeast to southwest, of (1) bedded chert, siliceous argillite, volcaniclastic turbidites, pillow basalt, and limestone of the Cannery Formation and the Porcupine Slate of Gilbert and others (1987); (2) greenschist-facies Paleozoic metasedimentary and metavolcanic rocks that have Permian cooling ages; (3) silty limestone and calcareous argillite interbedded with pillow basalt and volcaniclastic rocks of the Halleck Formation and the William Henry Bay area; and (4) intermediate-composition and syenitic plutons. These belts correspond to components of an accretionary complex, contemporary metamorphic rocks, forearc-basin deposits,

  13. On the metamorphic history of an Archaean granitoid greenstone terrane, East Pilbara, Western Australia, using the 40Ar/39Ar age spectrum technique

    International Nuclear Information System (INIS)

    Wijbrans, J.R.; McDougall, I.

    1987-01-01

    Age spectrum analyses of blue-green hornblendes from amphibolites from the Western Shaw Belt, East Pilbara, Western Australia, indicate an age of at least 3200 Ma for early regional metamorphism. Ages on hornblende and muscovite from the narrow contact zone with the adjacent Yule Batholith probably data updoming of the granitoid gneiss terranes at 2950 Ma. Hornblendes from within the Shaw Batholith and from a contact zone of a post-tectonic granitoid yield ages of 2840-2900 Ma, indicating either prolonged high temperatures within the granitoid gneiss terranes or a separate thermal pulse associated with the intrusion of post-tectonic granitoids. The preservation of very old hornblendes in a narrow greenstone belt surrounded by massive granitoid gneiss domes indicates that remarkable contrasts in metamorphic geotherms existed over short distances during the Late Archaean, suggesting that updoming occurred during a period of rapid tectonism. (orig.)

  14. On the metamorphic history of an Archaean granitoid greenstone terrane, East Pilbara, Western Australia, using the /sup 40/Ar//sup 39/Ar age spectrum technique

    Energy Technology Data Exchange (ETDEWEB)

    Wijbrans, J.R.; McDougall, I.

    1987-07-01

    Age spectrum analyses of blue-green hornblendes from amphibolites from the Western Shaw Belt, East Pilbara, Western Australia, indicate an age of at least 3200 Ma for early regional metamorphism. Ages on hornblende and muscovite from the narrow contact zone with the adjacent Yule Batholith probably data updoming of the granitoid gneiss terranes at 2950 Ma. Hornblendes from within the Shaw Batholith and from a contact zone of a post-tectonic granitoid yield ages of 2840-2900 Ma, indicating either prolonged high temperatures within the granitoid gneiss terranes or a separate thermal pulse associated with the intrusion of post-tectonic granitoids. The preservation of very old hornblendes in a narrow greenstone belt surrounded by massive granitoid gneiss domes indicates that remarkable contrasts in metamorphic geotherms existed over short distances during the Late Archaean, suggesting that updoming occurred during a period of rapid tectonism.

  15. Paleomagnetism of Early Paleozoic Rocks from the de Long Archipelago and Tectonics of the New Siberian Islands Terrane

    Science.gov (United States)

    Metelkin, D. V.; Chernova, A. I.; Matushkin, N. Y.; Vernikovskiy, V. A.

    2017-12-01

    The De Long archipelago is located to the north of the Anjou archipelago as a part of a large group between the Laptev Sea and the East Siberian Sea - the New Siberian Islands and consists of Jeannette Island, Bennett Island and Henrietta Island. These islands have been shown to be part of a single continental terrane, whose tectonic history was independent of other continental masses at least since the Ordovician. Paleomagnetic and precise geological data for the De Long archipelago were absent until recently. Only in 2013 special international field trips to the De Long Islands could be organized and geological, isotope-geochronological and paleomagnetic studies were carried out.On Jeannette Island a volcanic-sedimentary sequence intruded by mafic dikes was described. The age of these dikes is more likely Early Ordovician, close to 480 Ma, as evidenced by the results of our 40Ar/39Ar and paleomagnetic investigations of the dolerites as well as the result from detrital zircons in the host rocks published before. On Bennett Island, there are widespread Cambrian-Ordovician mainly terrigenous rocks. Paleomagnetic results from these rocks characterize the paleogeographic position of the De Long archipelago at 465 Ma and perhaps at 530 Ma, although there is no evidence for the primary origin of magnetization for the latter. On Henrietta Island the Early Cambrian volcanic-sedimentary section was investigated. A paleomagnetic pole for 520 Ma was obtained and confirmed by new 40Ar/39Ar results. Adding to our previous paleomagnetic data for the Anjou archipelago the extended variant of the apparent polar wander path for the New Siberian Island terrane was created. The established paleolatitudes define its location in the equatorial and subtropical zone no higher than 40 degrees during the Early Paleozoic. Because there are no good confirmations for true polarity and related geographic hemisphere we present two possibilities for tectonic reconstruction. But both these

  16. Paleomagnetic data from the Caborca terrane, Mexico: Implications for Cordilleran tectonics and the Mojave-Sonora megashear hypothesis

    Science.gov (United States)

    Molina Garza, Roberto S.; Geissman, John W.

    1999-04-01

    Two ancient magnetizations have been isolated in rocks of the Caborca terrane, northwest Mexico. The characteristic magnetizations of Neoproterozoic and Paleozoic miogeoclinal shelf-strata, arc-derived Lower Jurassic marine strata, and Jurassic volcanic and volcaniclastic rocks are of dual polarity and east-northeast declination (or south-southwest) and shallow inclination. Magnetizations in Neoproterozoic and Paleozoic miogeoclinal strata are interpreted as secondary (J*) and to be of similar age to those observed in Lower and Middle Jurassic rocks. Remanence acquisition is bracketed between about 190 and 160 Ma. The overall mean (D=15.0°, I=8.5° n=38 sites; six localities; k=19.1, α95=5.5°) suggests a moderate to large clockwise rotation of 12 to 50° (depending on reference direction assumed) of the Caborca terrane, and rocks of the Sonoran segment of the Cordilleran volcanic arc, with respect to the North America craton. When compared with expected inclinations, observed values are not anomalously steep, arguing against statistically significant southward latitudinal displacement of the Caborca block after remanence acquisition. Late Cretaceous intrusions yield primary, dual-polarity steep inclination ``K'' magnetizations (D=341.4°, I=52.3° n=10 sites; five localities; k=38.3, α95=7.9°) and have locally remagnetized Neoproterozoic and Jurassic strata. When present, secondary (K*) magnetizations in Neoproterozoic strata are of higher coercivity and higher unblocking temperature than the characteristic (J*) magnetization. Importantly, the regional internal consistency of data for Late Cretaceous intrusions suggests that effects of Tertiary tilt or rotation about a vertical axis over the broad region sampled (~5000 km2) are not substantial. Late Cretaceous primary (K) magnetizations and secondary (K*) magnetizations yield a combined mean of D=348.1°, I=50.7° (N=10 localities; 47 sites; k=53.5, α95=6.7°), indicating at most small (displacement is near

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

    Science.gov (United States)

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

    1994-01-01

    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

  18. Gravity and magnetic survey of the Oaxaca city region: Cenozoic horst-and-graben structure superimposed on the Oaxaca-Juarez terrane boundary, southern Mexico

    Science.gov (United States)

    Campos-Enríquez, J. O.; Belmonte-Jiménez, S. I.; Keppie, J. D.; Ortega-Gutiérrez, F.; Arzate, J. A.; Martínez-Silva, J.; Martínez-Serrano, R. G.

    2010-04-01

    A geophysical survey of the Oaxaca Fault along the north-trending Etla and Zaachila valleys area, southern Mexico, shows a series of NNW-SSE Bouguer and magnetic anomalies with steeper gradients towards the east. The Oaxaca Fault represents Tertiary extensional reactivation of the Juarez shear zone that constitutes the boundary between the Oaxaca and Juárez terranes. Cooperative interpretation of six combined gravity and magnetic NE-SW profiles perpendicular to the valleys indicates the presence of a composite depression comprising three N-S sub-basins: the northern Etla and southern Zaachila sub-basins separated by the Atzompa sub-basin. The Etla sub-basin is bounded by the moderately E-dipping, Etla Fault and the more steeply W-dipping Oaxaca Fault, which together constitute a graben that continues southwards into the Atzompa graben. The deeper Zaachila sub-basin, south of Oaxaca city, is a wide V-shaped graben with a horst in the middle. The new geophysical data suggest that the Oaxaca-Juarez terrane boundary is displaced sinistrally ca. 20 km along the E-W Donají Fault, which defines the northern boundary of the Zaachila sub-basin. On the other hand, the Oaxaca Fault may either continue unbroken southwards along the western margin of the horst in the Zaachila sub-basin or be offset along with the terrane boundary. The sinistral movement may have taken place either during the Late Mesozoic-Early Cenozoic, Laramide Orogeny as a lateral ramp in the thrust plane or under Miocene-Pliocene, NE-SW extension. The former suggests that the Donají Fault is a transcurrent fault, whereas the latter implies that it is a transfer fault. The models imply that originally the suture was continuous south of the Donaji Fault and provide a constraint for the accretion of the Oaxaca and Juarez terranes.

  19. Early Cretaceous I-type granites in the Tengchong terrane: New constraints on the late Mesozoic tectonic evolution of southwestern China

    Directory of Open Access Journals (Sweden)

    Yi Fang

    2018-03-01

    Full Text Available The Early Cretaceous granitoids that are widespread in the Tengchong terrane of Southwest China play a critical role in understanding the tectonic framework associated with the Tethyan oceans. In this study, we present a detailed description of zircon U–Pb ages, whole-rock geochemistry and Hf isotopes for the Laoxiangkeng pluton in the eastern Tengchong terrane and elucidate their petrogenesis and geodynamic implications. Zircon U–Pb dating of the Laoxiangkeng pluton yields ages of 114 ± 1 Ma and 115 ± 1 Ma, which imply an Early Cretaceous magmatic event. The Laoxiangkeng pluton enriched in Si and Na, is calc-alkaline and metaluminous, and has the characteristics of highly fractionated I-type granites. Zircons from the pluton have calculated εHf(t values of −12.7 to −3.7 and two-stage model ages of 1327–1974 Ma, respectively, indicating a mixed source of partial melting of Paleo-Neoproterozoic crust-derived compositions with some inputs of mantle-derived magmas. By integrating all available data for the regional tectonic evolution of the eastern Tethys tectonic domain, we conclude that the Early Cretaceous magmatism in the Tengchong terrane was produced by the northeastward subduction of the Meso-Tethyan Bangong–Nujiang Ocean.

  20. The tectono-magmatic evolution of the occidental terrane and the Paraiba do Sul Klippe within the Neoproterozoic Ribeira orogenic Belt, Southeastern Brazil

    International Nuclear Information System (INIS)

    Valladares, Claudia Sayao; Duarte, Beatriz Paschoal; Heilbron, Monica; Ragatky, Diana

    2000-01-01

    The occidental Terrane is envisaged as the eastern/southeastern reworked margin of the Sao Francisco/Rio de la Plata plate associated with and E-trending subduction under the Congo plate. The Paraiba do Sul Klippe is part of the Oriental Terrane, envisaged as a portion of the Congo plate. A collisional-stage resulted in intense westward deformation of the Occidental Terrane under intermediate pressure metamorphism (syn-D1+D2 events). A late-collisional stage resulted in subvertical folding and steep shear zones (D3 event). Both stages were associated with voluminous crustal-derived granites. U-Pb and Sm-Nd geochronology as well as geochemical and structural data point to three magmatic episodes: a syn-collisional stage 1; a syn-collisional stage 2; and a late-collisional stage. This paper presents a magmatic evolutionary model for this crustal segment of the Ribeira orogenic belt based on new geological data of Brasiliano granites and data available in the literature. (author)

  1. Petrography and geochronology (U/Pb-Sm/Nd) the Passagem Granite, Pensamiento Granitoid Complex, Paragua Terrane, SW Amazon Craton, Mato Grosso, Brazil

    International Nuclear Information System (INIS)

    Jesus, Gisely Carmo de; Sousa, Maria Zelia Aguiar de; Ruiz, Amarildo Salina; Matos, Joao Batista de

    2010-01-01

    The Passagem granite includes stocks, plugs and dikes located in the Ricardo Franco hill - Vila Bela da Santissima Trindade region - state of Mato Grosso, central Brazil. The Passagem Granite is included in the Paragua terrane - SW Amazonian Craton. It consists of isotropic monzogranite, sienogranite and more rarely granodiorites with leucocratic dark gray to white color. These rocks range from hypidomorphic inequigranular to xenomorphic texture, fine to medium grained. Biotite is the only primary mafic present as essential phase and characterize an expanded slightly acid sequence formed by a sub-alkaline magmatism of high-potassium calc-alkaline, slightly peraluminous composition from arc magmatic tectonic environment during a post-collisional period. Mechanism of fractional crystallization of plagioclase, biotite, titanite, apatite and zircon associated with simultaneous crustal assimilation are suggested for the evolution of these rocks. The results support the hypothesis of a post-collisional magmatism in the Paragua terrane at 1284 +- 20 Ma corresponding to the crystallization age of the Passagem granite. This paper propose that Passagem Granite represents as an extension in Brazilian terrane of the Pensamiento Granitoid Complex. (author)

  2. An oxygen isotope study of quartz veins within eclogites from the Dabie terrane

    Institute of Scientific and Technical Information of China (English)

    LI; Yiliang

    2001-01-01

    : 1011-1014.[23]Banerjee, S. K., Hunt, C. P., Liu, X., Separation of local signals from the regional paleomonsoon record of the Chinese loess plateau: A rock magnetic approach, Geophys. Res. Lett., 1993, 20: 843-846.[24]Vidic, N. J., TenPas, J. D., Verosub, K. L. et al., Separation of pedogenic and lithogenic components of magnetic suscepti-bility in the Chinese loess/paleosol sequence as determined by the CBD procedure and a mixing analysis, Geophys. J. Int., 2000, 142: 551-562.[25]Deng, C. L., Yuan, B. Y., Zhu, R. X. et al., Magnetic susceptibility of Holocene loess-black loam sequence from Jiaodao, Shanxi, before and after citrate-bicarbonate-dithionite extraction, Chinese Journal of Geophysics (in Chinese), 2000, 43(4): 514-520.[26]Hunt, C. P., Banerjee, S. K., Han, J. M. et al., Rock-magnetic proxies of climate change in the loess-palaeosol sequences of the western Loess Plateau of China, 1995, Geophys. J. Int., 1995, 123: 232-244.[27]Liu, X. M., Liu, T. S., Heller, F. et al., The grain size of magnetic minerals in Chinese loess and its implications for paleo-climate, Science in China (in Chinese), Ser. B, 1991, 21(6): 639-644.[28]Chen, F. H., Bloemendal, J., Feng, Z. D. et al., East Asian monsoon variations during oxygen isotope stage 5: Evidence from the northwestern margin of the Chinese Loess Plateau, Quaternary Science Reviews, 1999, 18: 1127-1135.[29]Pan, B. T., Wang, J. M., Loess record of Qinghai-Xizang Plateau monsoon variations in the eastern part of the plateau since the Last Interglacial, Quaternary Sciences (in Chinese), 1999, 19(4): 330-335.[30]Imbrie, J., Imbrie, J. Z., Modeling the climate response to orbital variation, Science, 1980, 207: 943-953.[31]Liu, T. S., Quaternary Environment (in Chinese), Beijing: Science Press, 1997, 189-239.

  3. Ancient terrane boundaries as probable seismic hazards: A case study from the northern boundary of the Eastern Ghats Belt, India

    Directory of Open Access Journals (Sweden)

    Saibal Gupta

    2014-01-01

    Full Text Available In the eastern part of the Indian shield, late Paleozoic–Mesozoic sedimentary rocks of the Talchir Basin lie precisely along a contact of Neoproterozoic age between granulites of the Eastern Ghats Mobile Belt (EGMB and amphibolite facies rocks of the Rengali Province. At present, the northern part of the basin experiences periodic seismicity by reactivation of faults located both within the basin, and in the Rengali Province to the north. Detailed gravity data collected across the basin show that Bouguer anomalies decrease from the EGMB (∼+15 mGal, through the basin (∼−10 mGal, into the Rengali Province (∼−15 mGal. The data are consistent with the reportedly uncompensated nature of the EGMB, and indicate that the crust below the Rengali Province has a cratonic gravity signature. The contact between the two domains with distinct sub-surface structure, inferred from gravity data, coincides with the North Orissa Boundary Fault (NOBF that defines the northern boundary of the Talchir Basin. Post-Gondwana faults are also localized along the northern margin of the basin, and present-day seismic tremors also have epicenters close to the NOBF. This indicates that the NOBF was formed by reactivation of a Neoproterozoic terrane boundary, and continues to be susceptible to seismic activity even at the present-day.

  4. An evolving tectonic environment of Late Carboniferous to Early Permian granitic plutons in the Chinese Altai and Eastern Junggar terranes, Central Asian Orogenic Belt, NW China

    Science.gov (United States)

    Zhang, Chen; Liu, Dongdong; Luo, Qun; Liu, Luofu; Zhang, Yunzhao; Zhu, Deyu; Wang, Pengfei; Dai, Quanqi

    2018-06-01

    The Central Asian Orogenic Belt (CAOB) represents one of the most important sites of juvenile crustal growth during the Phanerozoic. Located in the central part of the CAOB, the Chinese Altai and Eastern Junggar terranes record the collisional processes between the peri-Siberian and Kazakhstan orogenic systems. However, the precise timing of collision between the two terranes remains controversial. The Wukuli and Kadelat plutons in the Chinese Altai belt are dated at ∼305 and ∼280 Ma respectively, whereas the Aketas pluton in the Eastern Junggar terrane is dated at ∼308 Ma. Granites from the Wukuli and Kadelat plutons are strongly peraluminous (A/CNK > 1.1), and are characterized by low Al2O3, Na2O, MnO, MgO, CaO and heavy rare earth element (HREE) contents, but with high SiO2, K2O and Rb contents as well as high Rb/Sr ratios. Granites from the Wukuli pluton have low εNd(t) and εHf(t) values of -3.7 to -3.4 and -9.7 to +4.9, whereas those from the Kadelat pluton have values of -3.6 to -3.4 and -8.0 to +2.6. These features suggest S-type affinity for the Wukuli and Kadelat plutons with magma derivation through partial melting of Mesoproterozoic metasediments. The Aketas pluton is composed of weakly peraluminous quartz monzonites that have A/CNK values ranging from 0.92 to 1.08, with high Na2O, Sr, and Sr/Y, and low Y, Yb, Nb, and Ta. These rocks display positive εNd(t) (+4.8 to +6.4) and εHf(t) (+9.7 to +14.6) values, and low initial 87Sr/86Sr ratios (0.703357-0.703868), similar to modern adakites, suggesting that the quartz monzonites were derived from the partial melting of lower crustal material. The geochemical characteristics suggest that the Aketas pluton was formed in a subduction-related setting, the Wukuli pluton in a syn-collisional setting, and the Kadelat pluton in the subsequent post-orogenic strike-slip-related setting. In combination with data from other granitoids in these two terranes, the Aketas pluton represents the youngest record of

  5. Accumulation rates and sediment deposition in the northwestern Mediterranean

    Science.gov (United States)

    Zuo, Z.; Eisma, D.; Gieles, R.; Beks, J.

    As part of the EROS 2000 programme, sediment mixing and accumulation rates in the northwestern Mediterranean Sea were determined, applying the 210Pb dating method to a total of 49 cores, and the results from 29 sediment cores are presented here. On the basis of the results from the 49 sediment cores, an attempt was made to present a general picture of sediment accumulation for the area of the northwestern Mediterranean. The total deposition of sediment in the area is estimated to be of the order of 34±15 × 106 ton year-1, which is half the value reported earlier by Got and Aloisi (1990) (Continental Shelf Research, 10, 841-855) for the same region. The activity-depth profiles of 210Pb show the presence of intensive mixing in the upper layer of near-shore sediments, but little or no mixing is observed in the deep-water sediments. Based on a diffusion model, sediment mixing rates calculated from excess 210Pb gradients vary from 0·002 to 7· cm2 year-1, and the deposition rates from 0·01 to 0·60 cm year-1. A linear dependence of sedimentation rate on water depth derived from the sediment cores indicates an inverse correlation between these two. The relatively high sedimentation rates and mixing rates found near the Rhône River suggest that the contribution from the river dominates the deposition system in the northwestern Mediterranean. In the deep-water basin, however, atmospheric input and biological production are clearly more important.

  6. Climate Change and Neotectonic History of Northwestern China

    Science.gov (United States)

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

    1996-01-01

    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.

  7. Dynamics of dissolved organic carbon in the northwestern Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    DileepKumar, M.; Rajendran, A.; Somasundar, K.; Haake, B.; Jenisch, A.; Shuo, Z.; Ittekkot, V.; Desai, B.N.

    scatter of DOC and AOU data points. This scatter could have been also the result of POC oxida- tion to CO2. Sugimura and Suzuki (1988) have observed an inverse correlation be- tween AOU and DOC in the waters of the northwestern Pacific and claimed....e. positive AN) predominantly in the northern Arabian Sea. The slope of the regression line for all the points (-0.035) shows lower DOC values when AN is positive, indicating oxidation by NOj-. The most interest- ing part of the inverse trend in toto is...

  8. Neutron activation analysis in reconnaissance geochemical survey of Northwestern Mindoro

    International Nuclear Information System (INIS)

    Santos, G. Jr.; Fernandez, L.G.

    1987-01-01

    Instrumental neutron activation analysis (NAA) technique was used to analyze stream sediments collected in Northwestern Mindoro. The concentration levels of 18 elements were determined. It was noted that NAA is suitable for the determination of rare earth, gold, arsenic and cobalt among others because of favorable high neutron cross sections. Samples collected in regional reconnaissance geochemical surveys could be analyzed usng NAA technique to complement other non-nuclear techniques, such as atomic absorption and X-ray fluorescence analysis. (Author). 11 figs.; 2 tabs.; 12 refs

  9. Assessing the sampling strategy in the Northwestern Mediterranean Sea

    Science.gov (United States)

    Margirier, Félix; Testor, Pierre; Bosse, Anthony; Heslop, Emma; L'Hévéder, Blandine; Arsouze, Thomas; Houpert, Loic; Mortier, Laurent

    2017-04-01

    The deployment of numerous autonomous platforms (gliders, argo floats, moorings) added to the repeated ship cruises in the Northwestern Mediterranean Sea account for a considerable data coverage of the area through the past 10 years. In this study, we analyse the in-situ observations' ability to assess for the changes in the Northwester Mediterranean basin water masses properties over time. Comparing the observed time series for the different regions and different water masses to that of a glider simulator in the NEMO-Med12 model, we estimate both the quality of the model and the skill of the in-situ observations in reproducing the evolution of the basin properties.

  10. 76 FR 77214 - Hawaii Crustacean Fisheries; 2012 Northwestern Hawaiian Islands Lobster Harvest Guideline

    Science.gov (United States)

    2011-12-12

    ... Crustacean Fisheries; 2012 Northwestern Hawaiian Islands Lobster Harvest Guideline AGENCY: National Marine...: Notification of lobster harvest guideline. SUMMARY: NMFS establishes the annual harvest guideline for the commercial lobster fishery in the Northwestern Hawaiian Islands (NWHI) for calendar year 2012 at zero...

  11. 77 FR 5585 - Northwestern Mutual Series Fund, Inc. and Mason Street Advisors, LLC; Notice of Application

    Science.gov (United States)

    2012-02-03

    ... SECURITIES AND EXCHANGE COMMISSION [Investment Company Act Release No. 29939; File No. 812-13982] Northwestern Mutual Series Fund, Inc. and Mason Street Advisors, LLC; Notice of Application January 30, 2012... instruments. Applicants: Northwestern Mutual Series Fund, Inc. (``Company'') and Mason Street Advisors, LLC...

  12. Rotavirus Infection in Four States in North-western Nigeria | Aminu ...

    African Journals Online (AJOL)

    Background: Rotaviruses are associated with ~ 611,000 deaths worldwide and with 33,000 deaths in Nigeria in children < 5 years of age annually. However, limited data exit on rotavirus (RV) infection in North-western Nigeria. This study surveyed RV infection in four states in Northwestern Nigeria. Methods: During July ...

  13. A Comparative Analysis of Seismological and Gravimetric Crustal Thicknesses below the Andean Region with Flat Subduction of the Nazca Plate

    Directory of Open Access Journals (Sweden)

    Mario E. Gimenez

    2009-01-01

    Full Text Available A gravimetric study was carried out in a region of the Central Andean Range between 28∘ and 32∘ south latitudes and from 72∘ and 66∘ west longitudes. The seismological and gravimetrical Moho models were compared in a sector which coincides with the seismological stations of the CHARGE project. The comparison reveals discrepancies between the gravity Moho depths and those obtained from seismological investigations (CHARGE project, the latter giving deeper values than those resulting from the gravimetric inversion. These discrepancies are attenuated when the positive gravimetric effect of the Nazca plate is considered. Nonetheless, a small residuum of about 5 km remains beneath the Cuyania terrane region, to the east of the main Andean chain. This residuum could be gravimetrically justified if the existence of a high density or eclogitized portion of the lower crust is considered. This result differed from the interpretations from Project “CHARGE” which revealed that the entire inferior crust extending from the Precordillera to the occidental “Sierras Pampeanas” could be “eclogitized”. In this same sector, we calculated the effective elastic thickness (Te of the crust. These results indicated an anomalous value of Te = 30 km below the Cuyania terrane. This is further conclusive evidence of the fact that the Cuyania terrane is allochthonous, for which also geological evidences exist.

  14. Detrital rutile geochemistry and thermometry from the Dabie orogen: Implications for source-sediment links in a UHPM terrane

    Science.gov (United States)

    Liu, Lei; Xiao, Yilin; Wörner, G.; Kronz, A.; Simon, K.; Hou, Zhenhui

    2014-08-01

    This study explores the potential of detrital rutile geochemistry and thermometry as a provenance tracer in rocks from the Central Dabie ultrahigh-pressure metamorphic (UHPM) zone in east-central China that formed during Triassic continental collision. Trace element data of 176 detrital rutile grains selected from local river sediments and 91 rutile grains from distinct bedrocks in the Shuanghe and Bixiling areas, obtained by both electron microprobe (EMP) and in situ LA-ICP-MS analyses, suggest that geochemical compositions and thermometry of detrital rutiles are comparable to those from their potential source rocks. After certification of the Cr-Nb discrimination method for the Central Dabie UHPM zone, we show that 29% of the detrital rutiles in the Shuanghe area were derived from metamafic sources whereas in the Bixiling area that it is up to 76%. Furthermore, the proportion of distinct types of detrital rutiles combined with modal abundances of rutile in metapelites and metamafic bedrocks can be used to estimate the proportion of different source lithologies. Based on this method the proportion of mafic source rocks was estimated to ∼10% at Shuanghe and >60% at Bixiling, respectively, which is consistent with the proportions of eclogite (the major rutile-bearing metamafic rock) distribution in the field. Therefore, the investigation of detrital rutiles is a potential way to evaluate the proportion of metamafic rocks and even to prospect for metamafic bodies in UHPM terranes. Zr-in-rutile temperatures were calculated at different pressures and compared with temperatures derived from rock-in rutiles and garnet-clinopyroxene Fe-Mg thermometers. Temperatures calculated for detrital rutiles range from 606 °C to 707 °C and 566 °C to 752 °C in Shuanghe and Bixiling, respectively, at P = 3 GPa with an average temperatures of ca. 630 °C for both areas. These temperature averages and ranges are similar to those calculated for rutiles from surrounding source rocks

  15. Terrane-Scale Metastability in Subducted Himalayan Continental Crust as Revealed by Integrated Petrological and Geodynamic Modeling

    Science.gov (United States)

    Palin, R. M.; Reuber, G. S.; White, R. W.; Kaus, B. J. P.; Weller, O. M.

    2017-12-01

    The Tso Morari massif, northwest India, is one of only two regions in the Himalayan Range that exposes subduction-related ultrahigh-pressure (UHP) metamorphic rocks. The tectonic evolution of the massif is strongly debated, however, as reported pressure estimates for peak metamorphism range between 2.4 GPa and 4.8 GPa. Such ambiguity hinders effective lithospheric-scale modeling of the early stages of the orogen's evolution. We present the results of integrated petrological and geodynamic modeling (Palin et al., 2017, EPSL) that provide new quantitative constraints on the prograde-to-peak pressure-temperature-time (P-T-t) path, and predict the parageneses that felsic and mafic components of the massif crust should have formed under equilibrium conditions. Our model shows that peak P-T conditions of 2.6-2.8 GPa and 600-620 °C, representative of subduction to 90-100 km depth (assuming lithostatic pressure), were reached just 3 Myr after the onset of collision. These P-T-t constraints correlate well with those reported for similar UHP eclogite in the along-strike Kaghan Valley, Pakistan, suggesting that the northwest Himalaya contains dismembered remnants of a 400-km long UHP terrane comparable in size to the Western Gneiss Region, Norway, and the Dabie-Sulu belt, China. The extremely high pressures (up to 4.8 GPa) for peak metamorphism reported by some workers are likely to be unreliable due to thermobarometry having been performed on minerals that did not represent equilibrium assemblages. Furthermore, key high-P minerals predicted to form in subducted Tso Morari continental crust (e.g. jadeite, Mg-rich garnet) are absent from natural samples in the region, reflecting the widespread metastable preservation of lower-pressure protolith assemblages during subduction and exhumation. This result questions the reliability of geodynamic simulations of orogenesis that are commonly predicated on equilibrium metamorphism operating continuously throughout tectonic cycles.

  16. Silicate-Oxide Equilibria in the Wilson Lake Terrane, Labrador - Evidence for a Pre- Metamorphic Oxidizing Event

    Science.gov (United States)

    Korhonen, F. J.; Stout, J. H.

    2006-05-01

    The presence of Fe3+ and Ti in silicates and their presumed equilibration with Fe2+-Fe3+-Ti oxide minerals has long been recognized as an important factor in metamorphic phase equilibria. The Red Wine Mountains massif is a granulite facies unit in the Wilson Lake terrane of central Labrador, where this equilibration is especially important for estimating both temperature and fO2 during peak metamorphism. Peak assemblages are sapphirine + quartz, and orthopyroxene + sillimanite + quartz. The coexisting oxides, which are largely responsible for the pronounced aeromagnetic high of the massif, consist of nearly pure magnetite and an exsolved titanohematite. Estimates of fO2 based on magnetite + integrated titanohematite compositions are slightly below that defined by the pure magnetite-hematite buffer. This assemblage is also responsible for the magnetic signature of metagabbro and metanorite dikes, a fact which challenges the conventional wisdom that the high Fe3+ content of the host paragneisses was inherited from a highly oxidized ferruginous shale. We suggest here that prior to granulite facies metamorphism, an oxidizing hydrothermal event either coeval or following the emplacement of mafic dikes into the paragneiss host was responsible for the highly oxidized nature of the massif as a whole. Subsequent metamorphism then produced the observed assemblages. This scenario is supported by recent U-Pb zircon and monazite ages of ca. 1626 ± 10 Ma, which indicate that both metagabbro dikes and host paragneiss were metamorphosed at the same time. Dike emplacement and the oxidizing event must have preceded 1626 Ma. The implications of this pre-metamorphic oxidizing event is that Fe3+ becomes an inherent and fixed component in the chemical system during metamorphism. Phase relationships, preliminary thermodynamic modeling, and geothermobarometric constraints indicate that peak temperatures are lower than those previously determined for Fe3+-absent systems. More appropriate

  17. Early Jurassic Volcanism in the South Lhasa Terrane, Southern Tibet: Record of Back-arc Extension in the Active Continental Margin

    Science.gov (United States)

    Wei, Y.; Zhao, Z.; Zhu, D. C.; Wang, Z.; Liu, D.; Mo, X.

    2015-12-01

    Indus-Yarlung Zangbo Suture Zone (IYZSZ) represents the Mesozoic remnants of the Neo-Tethyan Ocean lithosphere after its northward subduction beneath the Lhasa Terrane. The evolution of the Neo-Tethyan Ocean prior to India-Asia collision remains unclear. To explore this period of history, we investigate zircon U-Pb geochronology, geochemistry and Nd-Hf isotopes of the Early Jurassic bimodal-like volcanic sequence around Dagze area, south Tibet. The volcanic sequence comprises calc-alkaline basalts to rhyolites whereas intermediate components are volumetrically restricted. Zircons from a basaltic andesite yielded crystallization age of 178Ma whereas those from 5 silicic rocks were dated at 183-174Ma, which suggest that both the basaltic and the silicic rocks are coeval. The basaltic rocks are enriched in LREE and LILE, and depleted in HFSE, with Epsilon Nd(t) of 1.6-4.0 and zircon Epsilon Hf(t) of 0.7-11.8, which implies that they were derived from a heterogenetic mantle source metasomatized by subduction components. Trace element geochemistry shows that the basaltic rocks are compositionally transitional from normal mid-ocean ridge basalts (N-MORB) to island arc basalts (IAB, e.g. Zedong arc basalts of ~160-155Ma in the south margin of Lhasa Terrane), with the signature of immature back-arc basin basalts. The silicic rocks display similar Nd-Hf isotopic features of the Gangdese batholith with Epsilon Nd(t) of 0.9-3.4 and zircon Epsilon Hf(t) of 2.4-17.7, indicating that they were possibly generated by anatexis of basaltic juvenile lower crust, instead of derived from the basaltic magma. These results support an Early to Middle Jurassic (183-155Ma) model that the back-arc extension tectonic setting were existing in the active continental margin in the south Lhasa Terrane.

  18. Sedimentology of Hirnantian glaciomarine deposits in the Balkan Terrane, western Bulgaria: Fixing a piece of the north peri-Gondwana jigsaw puzzle

    Science.gov (United States)

    Chatalov, Athanas

    2017-04-01

    Glaciomarine deposits of late Hirnantian age in the western part of the Palaeozoic Balkan Terrane have persistent thickness ( 7 m) and lateral uniformity in rock colour, bedding pattern, lithology, and sedimentary structures. Four lithofacies are distinguished from base to top: lonestone-bearing diamictites, interbedded structureless mudstones, crudely laminated diamictites, and finely laminated mudstones. The diamictites are clast-poor to clast-rich comprising muddy to sandy varieties. Their compositional maturity is evidenced by the very high amount of detrital quartz compared to the paucity of feldspar and unstable lithic grains. Other textural components include extraclasts derived from the local Ordovician basement, mudstone intraclasts, and sediment aggregates. Turbate structures, grain lineations, and soft sediment deformation of the matrix below larger grains are locally observed. Sedimentological analysis reveals that deposition occurred in an ice-intermediate to ice-distal, poorly agitated shelf environment by material supplied from meltwater buoyant plumes and rain-out from ice-rafted debris. Remobilization by mass-flow processes (cohesive debris flows and slumps) was an important mechanism particularly for the formation of massive diamictites. The glaciomarine deposits represent a typical deglaciation sequence reflecting retreat of the ice front (grounded or floating ice sheet), relative sea-level rise and gradually reduced sedimentation rate with increasing contribution from suspension fallout. This sequence was deposited on the non-glaciated shelf of the intracratonic North Gondwana platform along the southern margin of the Rheic Ocean. The Hirnantian strata of the Balkan Terrane can be correlated with similar glaciomarine deposits known from peri-Gondwana terranes elsewhere in Europe showing clear 'Armorican affinity'. Several lines of evidence suggest that the provenance of siliciclastic material was associated mainly with sedimentary recycling of

  19. The Dom Feliciano belt (Brazil-Uruguay)and its fore land (Rio de la Plata Craton): framework, tectonic evolution and correlations with similar terranes of southwestern Africa

    International Nuclear Information System (INIS)

    Basei, M.; Siga, O.; Masquelin, H.; Harara, O.; Reis Neto, J.; Preciozzi, F.

    2000-01-01

    The Dom Feliciano Belt (DFB) stretches for ca. 1,200 km along southeastern Brazil and eastern Uruguay, with an average width of 150 km. From its northern limit in Santa Catarina to its termination m Uruguay, DFB is internally organized according three crustal segments characterized, from southeast to northwest, by a Granitoid belt (calci-alkaline to alkaline granitoid rocks deformed to different degrees); a Schist belt (volcano-sedimentary rocks metamorphosed from green schist to amphibolite facies), and a Fore land belt (sedimentary and anchimetamorphic volcanic rocks), the latter situated between the Schist belt and the old western terranes. Despite discontinuously covered by younger sediments, the continuity of these three segments is suggested by the similar lithotypes and structural characteristics, as well as by the gravimetric geophysical signature.In this work, DBF is interpreted as the product of successive subduction s and collisions related to the agglutination of different terranes generated or intensely reworked from the Neoproterozoic to the Cambrian, during the Brasiliano and Rio Doce orogenesis, with maximum time starting at 900 Ma (opening of the Adamastor Ocean) and ending at 530 Ma (deformation of the fore land basins) related to the tecto no-magmatic events associated with the formation of the Western Gondwana.Besides the Neoproterozoic DFB and its fore land, the Rio de la Plata Craton and the Luis Alves Microplate, constituted by Paleoproterozoic gneissic-migmatitic rocks, two other tectonic units can be recognized in southeastern Brazil and eastern Uruguay: the Sao Gabriel Block (RS) where Neoproterozoic juvenile material can be characterized in regional scale (in great part associated with an island are), and the Punta del Este Terrane, which presents, in southern Uruguay, an ortho gneiss basement with ages around 1,000 Ma and a meta sedimentary cover (Rocha Group), which can correspond in the South-American portion, to the Namaqua and Gariep

  20. Zonal management of arsenic contaminated ground water in Northwestern Bangladesh.

    Science.gov (United States)

    Hill, Jason; Hossain, Faisal; Bagtzoglou, Amvrossios C

    2009-09-01

    This paper used ordinary kriging to spatially map arsenic contamination in shallow aquifers of Northwestern Bangladesh (total area approximately 35,000 km(2)). The Northwestern region was selected because it represents a relatively safer source of large-scale and affordable water supply for the rest of Bangladesh currently faced with extensive arsenic contamination in drinking water (such as the Southern regions). Hence, the work appropriately explored sustainability issues by building upon a previously published study (Hossain et al., 2007; Water Resources Management, vol. 21: 1245-1261) where a more general nation-wide assessment afforded by kriging was identified. The arsenic database for reference comprised the nation-wide survey (of 3534 drinking wells) completed in 1999 by the British Geological Survey (BGS) in collaboration with the Department of Public Health Engineering (DPHE) of Bangladesh. Randomly sampled networks of zones from this reference database were used to develop an empirical variogram and develop maps of zonal arsenic concentration for the Northwestern region. The remaining non-sampled zones from the reference database were used to assess the accuracy of the kriged maps. Two additional criteria were explored: (1) the ability of geostatistical interpolators such as kriging to extrapolate information on spatial structure of arsenic contamination beyond small-scale exploratory domains; (2) the impact of a priori knowledge of anisotropic variability on the effectiveness of geostatistically based management. On the average, the kriging method was found to have a 90% probability of successful prediction of safe zones according to the WHO safe limit of 10ppb while for the Bangladesh safe limit of 50ppb, the safe zone prediction probability was 97%. Compared to the previous study by Hossain et al. (2007) over the rest of the contaminated country side, the probability of successful detection of safe zones in the Northwest is observed to be about 25

  1. Late Triassic Porphyritic Intrusions And Associated Volcanic Rocks From The Shangri-La Region, Yidun Terrane, Eastern Tibetan Plateau: Implications For Adakitic Magmatism And Porphyry Copper Mineralization

    Science.gov (United States)

    Wang, B.; Zhou, M.; Li, J.; Yan, D.

    2011-12-01

    The Yidun terrane, located on the eastern margin of the Tibetan plateau, has been commonly considered to be a Triassic volcanic arc produced by subduction of the Ganzi-Litang oceanic lithosphere. The Yidun terrane is characterized by numerous arc-affinity granitic intrusions located along a 500-km-long, north-south-trending belt. Among these granitic bodies, several small porphyritic intrusions in the southern segment of the terrane (Shangri-La region) are associated with large porphyry copper deposits. These porphyritc intrusions are composed of diorite and quartz diorite, and spatially associated with andesites and dacites. LA-ICP-MS zircon U-Pb ages of the intrusions range from 230 to 215 Ma. The andesites and dacites are intercalated with slates and sandstones and have ages of around 220 Ma. The intrusive and volcanic rocks have SiO2 contents from 56.6 to 67.1 wt.%, Al2O3 from 14.2 to 17.4 wt.% and MgO from 1.9 to 4.2 wt.%. They show significant negative Nb-Ta anomalies on primitive mantle-normalized spidergrams. They have high La/Yb (13-49) ratios with no prominent Eu anomalies. All the rocks have high Sr (258-1980 ppm), and low Y (13-21 ppm) with high Sr/Y ratios (29-102). The geochemical features indicate that both the volcanic rocks and porphyritic intrusions were derived from adakitic magmas. They have similar initial 87Sr/86Sr ratios (0.7058 to 0.7077) and ɛNd (-1.88 to -4.93) values, but can be further divided into two groups: high silica (HSA) and low silica adakitic rocks (LSA). The HSA, representing an early stage of magmatism (230 to 215 Ma), were derived from oceanic slab melts with limited interaction with the overlying mantle wedge. At 215 Ma, more extensive interaction resulted in the formation of LSA. We propose that HSA were produced by flat subduction leading to melting of oceanic slab, whereas subsequent slab break-off caused the significant interaction between slab melts and the mantle wedge and thus the generation of the LSA. Compared with

  2. Draa Sfar, Morocco: A Visean (331 Ma) pyrrhotite-rich, polymetallic volcanogenic massive sulphide deposit in a Hercynian sediment-dominant terrane

    OpenAIRE

    Marcoux , Eric; Belkabir , Abdelhay; Gibson , Harold L.; Lentz , David; Ruffet , Gilles

    2008-01-01

    International audience; Draa Sfar is a Visean, stratabound, volcanogenic massive sulphide ore deposit hosted by a Hercynian carbonaceous, black shale-rich succession of the Jebilet terrane, Morocco. The ore deposit contains 10 Mt grading 5.3 wt.% Zn, 2 wt.% Pb, and 0.3 wt.% Cu within two main massive sulphides orebodies, Tazakourt (Zn-rich) and Sidi M'Barek (Zn–Cu rich). Pyrrhotite is by far the dominant sulphide (70 to 95% of total sulphides), sphalerite is fairly abundant, chalcopyrite and ...

  3. Palm harvest impacts in north-western South America

    DEFF Research Database (Denmark)

    Balslev, Henrik

    2011-01-01

    Tropical forests harbor thousands of useful plants that are harvested and used in subsistence economies or traded in local, regional or international markets. The effect on the ecosystem is little known, and the forests resilience is badly understood. Palms are the most useful group of plants...... in tropical American forests. This paper introduces a cross-disciplinary study of the effects of harvesting palm products from the tropical forests in north-western South America. The size of the resource is estimated through palm community studies in the different forest formations that determines the number...... of species and individuals of all palm species. The genetic structure of useful palm species is studied to determine how much harvesting of the species contributes to genetic erosion of its populations, and whether extraction can be made without harm. Almost all palm species are used in rural communities...

  4. Quaternary tectonics of recent basins in northwestern Armenia

    Science.gov (United States)

    Trifonov, V. G.; Shalaeva, E. A.; Saakyan, L. Kh.; Bachmanov, D. M.; Lebedev, V. A.; Trikhunkov, Ya. I.; Simakova, A. N.; Avagyan, A. V.; Tesakov, A. S.; Frolov, P. D.; Lyubin, V. P.; Belyaeva, E. V.; Latyshev, A. V.; Ozherelyev, D. V.; Kolesnichenko, A. A.

    2017-09-01

    New data on the stratigraphy, faults, and formation history of lower to middle Pleistocene rocks in Late Cenozoic basins of northwestern Armenia are presented. It has been established that the low-mountain topography created by tectonic movements and volcanic activity existed in the region by the onset of the Pleistocene. The manifestations of two geodynamic structure-forming factors became clear in Pleistocene: (i) collisional interaction of plates due to near-meridional compression and (ii) deep tectogenesis and magma formation expressed in the distribution of vertical movements and volcanism. The general uplift of the territory, which was also related to deep processes, reached 350-500 m in basins and 600-800 m in mountain ranges over the last 0.5 Ma. The early Pleistocene ( 1.8 Ma) low- and medium-mountain topography has been reconstructed by subtraction of the latest deformations and uplift of the territory. Ancient human ancestry appeared at that time.

  5. Land and federal mineral ownership coverage for northwestern Colorado

    Science.gov (United States)

    Biewick, L.H.; Mercier, T.J.; Levitt, Pam; Deikman, Doug; Vlahos, Bob

    1999-01-01

    This Arc/Info coverage contains land status and Federal mineral ownership for approximately 26,800 square miles in northwestern Colorado. The polygon coverage (which is also provided here as a shapefile) contains two attributes of ownership information for each polygon. One attribute indicates where the surface is State owned, privately owned, or, if Federally owned, which Federal agency manages the land surface. The other attribute indicates which minerals, if any, are owned by the Federal govenment. This coverage is based on land status and Federal mineral ownership data compiled by the U.S. Geological Survey (USGS) and three Colorado State Bureau of Land Management (BLM) former district offices at a scale of 1:24,000. This coverage was compiled primarily to serve the USGS National Oil and Gas Resource Assessment Project in the Uinta-Piceance Basin Province and the USGS National Coal Resource Assessment Project in the Colorado Plateau.

  6. Rifting and thermal evolution of the Northwestern Mediterranean

    Directory of Open Access Journals (Sweden)

    P. Chiozzi

    1995-06-01

    Full Text Available The structural setting of the Northwestern Mediterranean stems from tectonothermal processes which reflect on the nature of the crust. The Oligocene to Present evolution is here analysed with a thermal model which takes into account the significant extension of the continentallithosphere before the onset of sea-floor spread- ing in the bathyal zone. Subsidence data were used to set the boundaries of the oceanic realm which was com- pared with previous reconstructions inferred from other geophysical evidence. The thermal features of the transitional crust that lies between the oceanic crust and the stretched continental margins were also outlined. The Ligurian-Proven~al basin is a marginaI basin, whereas only the continental crust is expected in the Valen- cia trough. An evolutionary sketch of the study area that accounts for the observed subsidence and heat flux is proposed.

  7. Radiometric analysis of selected phosphorite deposits of northwestern Saudi Arabia

    International Nuclear Information System (INIS)

    Aksoy, A.; Matter, W.S.A.; El-Naggar, Z.R.

    1998-01-01

    Natural Gamma Ray Spectrometry Facility at the ERL was used on full time basis over a period of three months to measure quantitatively the natural gamma-ray activity in 50 selected phosphorite deposit samples from the northwestern part of Saudi Arabia. The results of the measurements show a U concentration between 9-127 ppm with an average of 42 ppm, Th concentration of 3-28 ppm with an average value of 10 ppm and K concentration in the 0.18-2.42 wt.% range with an average of 0.8%. The uncertainties were 0.3-4 % for U, 1- 17 % for Th and 0.7-15 % for K. The results will be presented and further geological interpretation of the results will be discussed using the relation between the content of K, U and Th and P 2 O 5 as well as from the relationship among uranium, thorium and potassium

  8. The use of photovoltaics for rural electrification in northwestern China

    Energy Technology Data Exchange (ETDEWEB)

    Wallace, W.L. [National Renewable Energy Lab., Golden, CO (United States); Li Jingming; Gao Shangbin [Chinese Ministry of Agriculture, Beijing (China)

    1998-09-01

    The use of renewable energy technologies in China is becoming increasingly important to meet the needs of a large rural population. Solar and wind renewable resources in particular are available in regions of China that at present have no access to conventional grid power. Two regions in China that have an acute lack of electricity are a large region in northern and western China and the coastal island region of China. These regions have attracted the attention of the Chinese government in terms of increasing the quality of life and standard of living conditions of the rural population. These regions have also attracted the attention of domestic Chinese companies and of international companies, governments, and multilateral development organizations as a potential market for renewable energy rural electrification systems. This paper focuses on the bilateral cooperation between the US Department of Energy and China in providing assistance for the use of renewable technologies for rural electrification in northwestern China.

  9. Age/isotopic characterisation of the Waipapa Group in Northland and Auckland, New Zealand, and implications for the status of the Waipapa Terrane

    International Nuclear Information System (INIS)

    Adams, C.J.; Maas, R.

    2004-01-01

    Rb-Sr ages of low-grade metasediments of the Waipapa Group (probable Permian-Jurassic) of Northland and Auckland range from Late Triassic (c. 209-217 Ma) to Middle Jurassic (c. 164-174 Ma), reflecting deformation and metamorphism during the Rangitata Orogeny. K-Ar ages indicate Middle Jurassic (c. 165-175 Ma) uplift and cooling of the western Omahuta-Puketi Forest block, and later, Middle-Late Jurassic (c. 150-160 Ma) cooling of the Helena Bay to Hunua Ranges eastern coastal block. In the intervening Western Bay of Islands block, there is evidence of local Early Cretaceous (c. 135 Ma) metamorphism. Rb-Sr whole-rock isochron age (t) and initial 87 Sr/ 86 Sr ratio (i) data support the assignment of Waipapa Group of the westernmost, Omahuta-Puketi block to the Caples Terrane. The remaining data have a consistent (t)-(i) signature, with (i) values 0.7039-0.7049, unlike Permian-Cretaceous Torlesse Supergroup metasediments with more radiogenic (i) values, typically >0.7060. They thus support the retention of a separate, Waipapa Terrane which continues southwards through central North Island to the Kaimanawa Ranges, and probably to Kapiti Island, and schist equivalents in eastern Marlborough. (author). 62 refs., 5 figs., 3 tabs

  10. The basement of the Punta de Este Terrane: A meso proterozoic heritage at the eastern border of Rio de La Plata craton

    International Nuclear Information System (INIS)

    Preciozzi, F.; Peel, E.; Sanchez, L.; Basei, M.

    2005-01-01

    U-Pb zircon ages between 1000 and 900 Ma corresponding to the nuclei of zircon crystals extracted from the basement of the Punta del Este Terrane (Eastern Uruguay) allowed the correlation of the protoliths of this domain with rocks attributed to the Namaqua Belt in Southwestern Africa. SHRIMP ages obtained for the ortho gneissic rocks allowed to place at ca. 750 Ma the generations of gneisses and migmatites. Differently from what occurred in Africa, reworking of this crustal segment during the Brasiliano-Pan african orogenesis was very intense, reaching the granulite facies around 640Ma. Acid volcanic and volcaniclastic rocks (Sierra de Aguirre Formation) with ages around 570 Ma, late sedimentary basins (San Carlos Formation) and post-tectonic granitoids (Santa Teresa and José Ignacio batholith s) mark the end of the events related with the Brasiliano/Pan-African orogenesis. The final collision between the Punta del Este Terrane and the western domains represented by the Dom Feliciano Belt and the Río de La Plata Craton may have occurred at around 535 Ma

  11. A submerged temple complex off Pindara, on the northwestern coast of Saurashtra

    Digital Repository Service at National Institute of Oceanography (India)

    Gaur, A.S.; Sundaresh; Tripati, S.

    Pindara has been an important religious centre since the early historical period as it has been recorded in several ancient texts. An onshore exploration on the northwestern coast of Saurashtra brought to light the remains of a temple complex...

  12. Composition and diversity of northwestern Amazonian rainforests in a geoecological context

    NARCIS (Netherlands)

    Duivenvoorden, J.F.; Duque, A.J.; Hoorn, C.; Wesselingh, F.P.

    2010-01-01

    The northwestern Amazonian landscape includes most of the representative landscape units that characterize Amazonia, and for this reason it constitutes an excellent place to investigate relationships between the abiotic environment (geology, geomorphology, soils) and biodiversity. In this review we

  13. The vegetation of the north-western Orange Free State, South Africa. 1. Physical environment

    Directory of Open Access Journals (Sweden)

    M. S. Kooij

    1990-10-01

    Full Text Available The physiography, geology, soil, land types and climate of the north-western Orange Free State are described. The description provides a contextual framework for the subsequent vegetation classification.

  14. Benthic Macroinvertebrate Community Assessment, Northwestern Hawaiian Islands, October 2000, (NODC Accession 0002301)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Northwestern Hawaiian lslands were sampled during October 2000 at 63 stations on 9 atolls or islands under the lead of NOAA. This work is affiliated with the...

  15. Northwestern Hawaiian Islands Benthic Macroinvertebrate Community Assessment, 2000-10 (NODC Accession 0002301)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Northwestern Hawaiian islands were sampled during October 2000 at 63 stations on 9 atolls or islands under the lead of NOAA. This work is affiliated with the...

  16. Spatial zonation of zooplankton in the northwestern Arabian Sea: A multivariate approach

    Digital Repository Service at National Institute of Oceanography (India)

    Jayalakshmy, K.V.

    Latitudinal variation in abundance, diversity, dominance pattern and zonation of the major groups of zooplankton was studied n the coastal waters of northwestern Arabian Sea, between 25°44' N and 10°44' N. Maxwell Boltzmann Statistic...

  17. Environmental Assessment of the Buccaneer Oil Field in the Northwestern Gulf of Mexico 1978-1979

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains analytical data from samples acquired from the Northwestern Gulf of Mexico area under contract to the Environmental Protection Agency (EPA)...

  18. CRED Gridded Bathymetry near Northampton Seamounts (100-004), Northwestern Hawaiian Islands

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — File 100-004b is a 60-m ASCII grid of depth data collected near Northampton Seamounts in the Northwestern Hawaiian Islands as of May 2003. This grid has been...

  19. 2005 Reson 8101ER Multibeam Sonar Data from Cruise AHI-05-08 - Northwestern Hawaiian Islands

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Reson 8101ER multibeam Data were collected from 11-31 October 2006 aboard NOAA Survey Launch Acoustic Habitat Investigator (AHI) at at Maro Reef in the Northwestern...

  20. EOP Habitat and reef fish assemblages of banks in the Northwestern Hawaiian Islands

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Relational data table for SCUBA diving surveys on the bank of the Northwestern Hawaiian Islands, which were published in a manuscript named in the title above. These...

  1. [High energy physics research]: Annual performance report, December 1, 1991--November 30, 1992. [Northwestern Univ

    Energy Technology Data Exchange (ETDEWEB)

    Rosen, J; Block, M; Buchholz, D; Gobbi, B; Schellman, H; Buchholz, D; Rosen, J; Miller, D; Braaten, E; Chang, D; Oakes, R; Schellman, H

    1992-01-01

    The various segments of the Northwestern University high energy physics research program are reviewed. Work is centered around experimental studies done primarily at FNAL; associated theoretical efforts are included.

  2. 78 FR 9327 - Hawaii Crustacean Fisheries; 2013 Northwestern Hawaiian Islands Lobster Harvest Guideline

    Science.gov (United States)

    2013-02-08

    ... 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 (NMFS), National Oceanic and Atmospheric Administration (NOAA), Commerce...

  3. 76 FR 4551 - Hawaii Crustacean Fisheries; 2011 Northwestern Hawaiian Islands Lobster Harvest Guideline

    Science.gov (United States)

    2011-01-26

    ... 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 (NMFS), National Oceanic and Atmospheric Administration (NOAA), Commerce...

  4. Circum-Pacific accretion of oceanic terranes to continental blocks: accretion of the Early Permian Dun Mountain ophiolite to the E Gondwana continental margin, South Island, New Zealand

    Science.gov (United States)

    Robertson, Alastair

    2016-04-01

    Accretionary orogens, in part, grow as a result of the accretion of oceanic terranes to pre-existing continental blocks, as in the circum-Pacific and central Asian regions. However, the accretionary processes involved remain poorly understood. Here, we consider settings in which oceanic crust formed in a supra-subduction zone setting and later accreted to continental terranes (some, themselves of accretionary origin). Good examples include some Late Cretaceous ophiolites in SE Turkey, the Jurassic Coast Range ophiolite, W USA and the Early Permian Dun Mountain ophiolite of South Island, New Zealand. In the last two cases, the ophiolites are depositionally overlain by coarse clastic sedimentary rocks (e.g. Permian Upukerora Formation of South Island, NZ) that then pass upwards into very thick continental margin fore-arc basin sequences (Great Valley sequence, California; Matai sequence, South Island, NZ). Field observations, together with petrographical and geochemical studies in South Island, NZ, summarised here, provide evidence of terrane accretion processes. In a proposed tectonic model, the Early Permian Dun Mountain ophiolite was created by supra-subduction zone spreading above a W-dipping subduction zone (comparable to the present-day Izu-Bonin arc and fore arc, W Pacific). The SSZ oceanic crust in the New Zealand example is inferred to have included an intra-oceanic magmatic arc, which is no longer exposed (other than within a melange unit in Southland), but which is documented by petrographic and geochemical evidence. An additional subduction zone is likely to have dipped westwards beneath the E Gondwana margin during the Permian. As a result, relatively buoyant Early Permian supra-subduction zone oceanic crust was able to dock with the E Gondwana continental margin, terminating intra-oceanic subduction (although the exact timing is debatable). The amalgamation ('soft collision') was accompanied by crustal extension of the newly accreted oceanic slab, and

  5. Triassic arc-derived detritus in the Triassic Karakaya accretionary complex was not derived from either the S Eurasian margin (Istanbul terrane) or the N Gondwana margin (Taurides)

    Science.gov (United States)

    Ustaömer, Timur; Ayda Ustaömer, Petek; Robertson, Alastair H. F.; Gerdes, Axel; Zulauf, Gernold

    2014-05-01

    We present new U-Pb zircon source age data for Upper Triassic sandstones of the Istanbul Terrane (S Eurasian margin) and also for Triassic sandstones of the Taurides (N Gondwana margin). The main aim is to detect and quantify the contribution of Triassic magmatism as detritus to either of these crustal blocks. This follows the recent discovery of a Triassic magmatic arc source for the Triassic sandstones of the Palaeotethyan Karakaya subduction-accretion complex (Ustaömer et al. 2013; this meeting). Carboniferous (Variscan) zircon grains also form a significant detrital population, plus several more minor populations. Six sandstone samples were studied, two from the İstanbul Terrane (Bakırlıkıran Formation of the Kocaeli Triassic Basin) and four from the Tauride Autochthon (latest Triassic Üzümdere Formation and Mid-Triassic Kasımlar Formations; Beyşehir region). Detrital zircon grains were dated by the laser ablation-inductively coupled plasma-mass spectrometer (LA-ICP-MS) U-Pb method at Goethe University, Frankfurt. Our results do not reveal Triassic detritus in the Üzümdere Formation. The U-Pb age of the analysed zircon grains ranges from 267 Ma to 3.2 Ga. A small fraction of Palaeozoic zircons are Permian (267 to 296 Ma), whereas the remainder are Early Palaeozoic. Ordovician grains (4%) form two age clusters, one at ca. 450 Ma and the other at ca. 474 Ma. Cambrian-aged grains dominate the zircon population, while the second largest population is Ediacaran (576 to 642 Ma). Smaller populations occur at 909-997 Ma, 827-839 Ma, 1.8-2.0 Ga and 2.4-2.6 Ga. The sandstones of the Kasımlar Formation have similar zircon age cluster to those of the somewhat younger Üzümdere Formation, ranging from 239 Ma to 2.9 Ga. A few grains gave Anisian ages. Cambrian zircon grains are less pronounced than in the Kasımlar Formation compared to the Üzümdere Formation. The detrital zircon record of Tauride sandstones, therefore, not indicates significant contribution

  6. Geomorphological context of the basins of Northwestern Peninsular Malaysia

    Science.gov (United States)

    Sautter, Benjamin; Pubellier, Manuel; Menier, David

    2014-05-01

    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

  7. Uncertainty in 14C model ages of groundwater: The influence of soil gas in terranes dominated by C3 plants

    Science.gov (United States)

    Nelson, S.; Hart, R.; Eggett, D.

    2009-12-01

    Groundwater is the largest source of fresh water readily available to humanity and aquifers with long residence times are particularly susceptible to overuse. Thus, it is important to have quantitative estimates of the residence time of water in such aquifers. Many models used to calculate 14C ages of groundwater depend on an estimate of the δ13C value of carbon dioxide in soil at the time of recharge, a value that must be estimated. Other work has suggested that for terranes dominated by C3 plants, -23‰ is an appropriate value, and sensitivity calculations show that the apparent age of a groundwater is strongly dependent on the choice of this parameter. This is especially true where the measured values of δ13C of dissolved inorganic carbon (DIC) are used to estimate the contribution of “dead” carbon to the DIC load via the dissolution of calcite in the aquifer and soil zones. To better understand the temporal and spatial isotopic and abundance variability of soil carbon dioxide, we established soil gas sampling sites that encompassed a wide variety of settings in terms of season, elevation, climate, and plant community that were sampled monthly throughout regions of the state of Utah where C3 flora dominate. Direct measurements of soil gas suggest a value of -21.8 ± 1.4‰ (1σ) is a good input variable as long as: a) C3 vegetation dominates, and b) extreme aridity does not prevail such that plant densities and soil microbial activities are minimized. If recharge is envisaged to occur during spring and early summer in highly vegetated uplands, a value of -24.0 ± 0.6‰ may be more appropriate as statistical analysis reveals that seasonality and plant density are most clearly correlated to the carbon isotope composition of carbon dioxide in soil gas. Although the two values and ranges cited above values do not diverge strongly from other published estimates, they place fairly narrow limits on the uncertainty of ±500 and ±200 yr., respectively, in

  8. Shaping the Australian crust over the last 300 million years: insights from fission track thermotectonic imaging and denudation studies of key terranes

    International Nuclear Information System (INIS)

    Kohn, B.P.; Gleadow, A.J.W.; Brown, R.W.; O'Sullivan, P.B.; Foster, D.A.; Gallagher, K.

    2002-01-01

    Apatite fission track thermochronology is a well-established tool for reconstructing the low-temperature thermal and tectonic evolution of continental crust. The variation of fission track ages and distribution of fission track lengths are primarily controlled by cooling, which may be initiated by earth movements and consequent denudation at the Earth's surface and/or by changes in the thermal regime. Using numerical forward-modelling procedures these parameters can be matched with time-temperature paths that enable thermal and tectonic processes to be mapped out in considerable detail. This study describes extensive Australian regional fission track datasets that have been modelled sequentially and inverted into time-temperature solutions for visualisation as a series of time-slice images depicting the cooling history of present-day surface rocks during their passage through the upper crust. The data have also been combined with other datasets, including digital elevation and heat flow, to image the denudation history and the evolution of palaeo-topography. These images provide an important new perspective on crustal processes and landscape evolution and show how important tectonic and denudation events over the last 300 million years can be visualised in time and space. The application of spatially integrated denudation-rate chronology is also demonstrated for some key Australian terranes including the Lachlan and southern New England Orogens of southeastern Australia, Tasmania, the Gawler Craton, the Mt lsa lnlier, southwestern Australian crystalline terranes (including the Yilgarn Craton) and the Kimberley Block. This approach provides a readily accessible framework for quantifying the otherwise undetectable, timing and magnitude of long-term crustal denudation in these terranes, for a part of the geological record previously largely unconstrained. Discrete episodes of enhanced denudation occurred principally in response to changes in drainage, base

  9. Map Showing Geologic Terranes of the Hailey 1°x2° Quadrangle and the western part of the Idaho Falls 1°x2° Quadrangle, south-central Idaho

    Data.gov (United States)

    Department of the Interior — The paper version of Map Showing Geologic Terranes of the Hailey 1°x2° Quadrangle and the western part of the Idaho Falls 1°x2° Quadrangle, south-central Idaho was...

  10. Accumulation of organic carbon in northwestern Arabian sea sediments

    International Nuclear Information System (INIS)

    Khan, A.A.

    1999-01-01

    In this study accumulation of organic carbon in marine sediments of northwestern Arabian sea has been discussed. This paper presents the geochemical analysis of Organic carbon content and accumulation, delta 13 stable carbon isotope and Ba/Al. The primary objective was to investigate the high resolution information about the variations in paleoproductivity and source of organic matter in sediments below an upwelling area. Undisturbed sediments (Piston core NIOP-486) of late Pleistocene time were collected during Netherlands Indian Ocean Program (NIOP-1992-93). The core NIOP-486 was raised from a depth of 2077 meters near the Owen Ridge. This core records deposition history of last 200,000 years and includes 4 warm and 3 cold periods. The distribution of organic carbon content in studied core shows a pronounced cyclicity during glacial and interglacial stages. Organic carbon accumulation trends show that high sedimentation rates in glacial stages results in rapid burial and hence increase organic carbon accumulation. Paleoproductivity indicator Ba/Al has been used to compare with the organic carbon content and is correlated with the warm and cold periods variations in monsoons upwelling intensity. Generally, low paleoproductivity is found in glacial stages. The organic carbon content and accumulation, in sediments however seems to differ from the paleoproductivity trends shown by Ba/Al in glacial sediments of stage 6. Delta 13 C.org isotope results of the core NIOP-486 confirm that organic matter in sediments is predominantly marine (-20 to -23% ). (author)

  11. Evaluation of seismic hazard at the northwestern part of Egypt

    Science.gov (United States)

    Ezzelarab, M.; Shokry, M. M. F.; Mohamed, A. M. E.; Helal, A. M. A.; Mohamed, Abuoelela A.; El-Hadidy, M. S.

    2016-01-01

    The objective of this study is to evaluate the seismic hazard at the northwestern Egypt using the probabilistic seismic hazard assessment approach. The Probabilistic approach was carried out based on a recent data set to take into account the historic seismicity and updated instrumental seismicity. A homogenous earthquake catalogue was compiled and a proposed seismic sources model was presented. The doubly-truncated exponential model was adopted for calculations of the recurrence parameters. Ground-motion prediction equations that recently recommended by experts and developed based upon earthquake data obtained from tectonic environments similar to those in and around the studied area were weighted and used for assessment of seismic hazard in the frame of logic tree approach. Considering a grid of 0.2° × 0.2° covering the study area, seismic hazard curves for every node were calculated. Hazard maps at bedrock conditions were produced for peak ground acceleration, in addition to six spectral periods (0.1, 0.2, 0.3, 1.0, 2.0 and 3.0 s) for return periods of 72, 475 and 2475 years. The unified hazard spectra of two selected rock sites at Alexandria and Mersa Matruh Cities were provided. Finally, the hazard curves were de-aggregated to determine the sources that contribute most of hazard level of 10% probability of exceedance in 50 years for the mentioned selected sites.

  12. Geology of Northwestern Switzerland - with special emphasis on Opalinus Clay

    International Nuclear Information System (INIS)

    Burkhard, M.

    2007-01-01

    This report describes the variations of the geological structures of Northwestern Switzerland during about the last 200 million years. This gives an explanation for the present partition of the different rock layers in the studied domain. The geology of Switzerland is dominated by the formation of the Alps. The Mont Terri geology is best explained within the framework of the tectonic Wilson cycle: assembly of Pangea in Late Paleozoic times culminating in the Variscan orogeny, collapse and decay of this earlier mountain chain, peneplanation and new rifting leading to the opening of the alpine Tethys Ocean during the Mesozoic, followed by plate convergence, subduction, collision and new mountain-building in the Neogene. The Mont Terri geology bears witness to the same suite of events as the Alps; tectonically speaking, Mont Terri is part of the Alps. Africa continues to push Apulia against the larger European plate and the question arises as to what the geological future has in store for our hills and mountains. Recent GPS (Global Positioning System) data Iead to believe that it will be just erosion and decay

  13. The Effects of Sandstorms on the Climate of Northwestern China

    Directory of Open Access Journals (Sweden)

    Tiantian Hu

    2017-01-01

    Full Text Available In this paper, we investigate the observational direct radiation characteristics of several sandstorm events in Northwestern China (NWC. A simulating sensitivity experiment was designed to reduce the downward radiation in RegCM4 to investigate the climatic impacts and persistence of the direct radiation effect (DRE from dust aerosols in sandstorms. The results show that dust aerosols in sandstorms can change the radiation heating rate of the atmosphere, heating the air in the middle and low troposphere and cooling Earth’s surface. The climate effects of continuous and intense sandstorms in April in NWC can reach downstream areas such as Southeast and Northeast China and can persist for months. The dust aerosols in sandstorms can enhance diabatic heating and moisture loss. Therefore, dust storms lead to the environment in NWC becoming warmer and dryer. Through analysis of the dust tracer total burden, we identified that the enhancement of the dust total burden in the arid region illustrated that the DRE of dust aerosol in sandstorm process can react with the dust emission, thus forming a self-feedback loop. The DRE can persist three months.

  14. Antimicrobial activity of Northwestern Mexican plants against Helicobacter pylori.

    Science.gov (United States)

    Robles-Zepeda, Ramón E; Velázquez-Contreras, Carlos A; Garibay-Escobar, Adriana; Gálvez-Ruiz, Juan C; Ruiz-Bustos, Eduardo

    2011-10-01

    Helicobacter pylori is the major etiologic agent of such gastric disorders as chronic active gastritis and gastric carcinoma. Over the past few years, the appearance of antibiotic-resistant bacteria has led to the development of better treatments, such as the use of natural products. This study evaluated the anti-H. pylori activity of 17 Mexican plants used mainly in the northwestern part of Mexico (Sonora) for the empirical treatment of gastrointestinal disorders. The anti-H. pylori activity of methanolic extracts of the plants was determined by using the broth microdilution method. The 50% minimum inhibitory concentrations ranged from less than 200 to 400 μg/mL for Castella tortuosa, Amphipterygium adstringens, Ibervillea sonorae, Pscalium decompositum, Krameria erecta, Selaginella lepidophylla, Pimpinella anisum, Marrubium vulgare, Ambrosia confertiflora, and Couterea latiflora and were greater than 800 μg/mL for Byophyllum pinnatum, Tecoma stans linnaeus, Kohleria deppena, Jatropha cuneata, Chenopodium ambrosoides, and Taxodium macronatum. Only Equisetum gigantum showed no activity against H. pylori. This study suggests the important role that these plants may have in the treatment of gastrointestinal disorders caused by H. pylori. The findings set the groundwork for further characterization and elucidation of the active compounds responsible for such activity.

  15. Geosites inventory of the northwestern Tabular Middle Atlas of Morocco

    Science.gov (United States)

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

    2008-07-01

    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.

  16. Deformation of the Northwestern Okhotsk Plate: How is it happening?

    Science.gov (United States)

    Hindle, D.; Fujita, K.; Mackey, K.

    2009-09-01

    The Eurasia (EU) - North America (NA) plate boundary zone across Northeast Asia still presents many open questions within the plate tectonic paradigm. Constraining the geometry and number of plates or microplates present in the plate boundary zone is especially difficult because of the location of the EU-NA euler pole close to or even upon the EU-NA boundary. One of the major challenges remains the geometry of the Okhotsk plate (OK). whose northwestern portion terminates on the EU-OK-NA triple junction and is thus caught and compressed between converging EU and NA. We suggest that this leads to a coherent and understandable large scale deformation pattern of mostly northwest-southeast trending strike-slip faults which split Northwest OK into several extruding slivers. When the fault geometry is analysed together with space geodetic and focal mechanism data it suggests a central block which is extruding faster bordered east and west by progressively slower extruding blocks until the OK plate boundary faults are encountered. Taking into account elastic loading from both the intra-OK faults and the OK-Pacific (PA) boundary reconciles geodetic motions with geologic slip rates on at least the OK-NA boundary which corresponds to the Ulakhan fault.

  17. Northwestern University Schizophrenia Data and Software Tool (NUSDAST

    Directory of Open Access Journals (Sweden)

    Lei eWang

    2013-11-01

    Full Text Available 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.

  18. Urban heat island investigations in Arctic cities of northwestern Russia

    Science.gov (United States)

    Shumilov, Oleg I.; Kasatkina, Elena A.; Kanatjev, Alexander G.

    2017-12-01

    Urban microclimate peculiarities in two Arctic cities in northwestern Russia—Kirovsk (67.62°N, 33.67°E) and Apatity (67.57°N, 33.38°E)—were investigated by using mobile temperature records. The experiment was carried out in and around Apatity and Kirovsk in February 2014 and December 2016. The DS18B20 digital thermometer was installed on the roof of a car (height: approximately 1.2 m) to measure and record temperature variations automatically. In addition to the digital thermometer, the car was also equipped with an onboard global positioning system, allowing every temperature measurement to be referenced with an altitude and a latitude/longitude position. The possibility of urban heat island formation in these polar cities, above the Arctic Circle, was studied. Our analysis indicated that on 11 February 2014, the temperature varied in accordance with the background environmental lapse rate (-0.0045°C m-1), and nearly corresponded to it (-0.0165°C m-1) on 12 February 2014. On 6 December 2016, a strong local temperature inversion with a positive value of 0.032°C m-1 was detected, seemingly caused by the formation of a cold air pool in the valley near Kirovsk. It was found that the temperature variations within and outside these cities are strongly influenced by local topographic effects and the physical conditions of the atmospheric boundary layer.

  19. Clinical experience with PACS at Northwestern: year two

    Science.gov (United States)

    Channin, David S.; Hawkins, Rodney C.; Enzmann, Dieter R.

    2001-08-01

    We have previously described the PACS configuration at Northwestern Memorial Hospital (NMH). As opposed to an imaging modality, PACS is an evolving system that continuously grows and changes to meet the needs of the institution. The NMH PACS has grown significantly in the past year and has undergone significant architectural enhancements. This growth and evolutionary change will be described and discussed. The system now contains over 339,000 studies consisting of over 13 million images. There are now two short-term RAID storage units that provide for twice as much fast storage. There are also two magneto-optical disk jukeboxes providing long-term archive. We have deployed a redundant database to improve reliability of the system in the event of database failure. The number of modalities connected to the system has increased and will be summarized. Statistics describing utilization of the PACS will be shown. Lastly, we will discuss our plans for exploiting the application service provider model in our PACS environment.

  20. Reciprocity on Demand : Sharing and Exchanging Food in Northwestern Namibia.

    Science.gov (United States)

    Schnegg, Michael

    2015-09-01

    Two competing models concerning food transfers prominent in the anthropological literature conceptualize such transfers either as sharing or as exchange. Sharing is understood as situational transactions formed through demands and unconditional giving, whereas reciprocal exchange is understood in terms of networking and keeping score. I propose that the picture is more complicated than these classifications suggests. Drawing on data collected in Northwestern Namibia, I show that sharing and reciprocal exchange are dynamically interrelated in actual food transfers. As a local norm, people can demand food from anyone, and they are typically given food in response to a demand. However, in practice, food transfer networks emerge (N = 62) that are highly reciprocal and fit the exchange model much better. Although the sharing norm makes no restrictions on whom to ask, in practice people often turn to their neighbors. Interpersonal dynamics account for why some of those ties become strongly reciprocal and others do not. Under these circumstances, unconditional sharing, a norm that has been viewed as an alternative to exchange, can lead to reciprocity via reciprocity on demand.

  1. Mantle accretion evidence during the neoproterozoic of the Pernambuco-Alagoas terrane, and its significance to the evolution of the Borborema Province, NE Brazil

    International Nuclear Information System (INIS)

    Silva Filho, A.F.; Guimaraes, I.P; Van Schmus, W.R

    2001-01-01

    The Borborema Province is located in NE Brazil, corresponding to the western part of a major fold belt, which extends from Brazil to West Africa. According to paleogeographic reconstruction, it is located between the Congo, Sao Francisco and West Africa cratons. The Pernambuco-Alagoas Terrane is a major tectonic unit of the Borborema Province and comprises high-grade metamorphic sequences and the greatest granitic batholiths of this province. The granitic batholiths Maribondo-Correntes, Buique-Paulo Afonso and Aguas Belas-Caninde and their ortho derived country rocks show metaluminous and peraluminous compositions, and εNd(0,60 Ga) between +3,2 and -2,0 and T DM between 0,90 Ga and 1,20 Ga. These Nd isotope data favour a crustal evolution hypothesis involving accretion of juvenile material at least during the Brasiliano orogenesis collision and perhaps the formation of a juvenile lithosphere during the end of the Mesoproterozoic (au)

  2. Regional framework and geology of iron oxide-apatite-rare earth element and iron oxide-copper-gold deposits of the Mesoproterozoic St. Francois Mountains Terrane, southeast Missouri

    Science.gov (United States)

    Day, Warren C.; Slack, John F.; Ayuso, Robert A.; Seeger, Cheryl M.

    2016-01-01

    This paper provides an overview on the genesis of Mesoproterozoic igneous rocks and associated iron oxide ± apatite (IOA) ± rare earth element, iron oxide-copper-gold (IOCG), and iron-rich sedimentary deposits in the St. Francois Mountains terrane of southeast Missouri, USA. The St. Francois Mountains terrane lies along the southeastern margin of Laurentia as part of the eastern granite-rhyolite province. The province formed during two major pulses of igneous activity: (1) an older early Mesoproterozoic (ca. 1.50–1.44 Ga) episode of volcanism and granite plutonism, and (2) a younger middle Mesoproterozoic (ca. 1.33–1.30 Ga) episode of bimodal gabbro and granite plutonism. The volcanic rocks are predominantly high-silica rhyolite pyroclastic flows, volcanogenic breccias, and associated volcanogenic sediments with lesser amounts of basaltic to andesitic volcanic and associated subvolcanic intrusive rocks. The iron oxide deposits are all hosted in the early Mesoproterozoic volcanic and volcaniclastic sequences. Previous studies have characterized the St. Francois Mountains terrane as a classic, A-type within-plate granitic terrane. However, our new whole-rock geochemical data indicate that the felsic volcanic rocks are effusive derivatives from multicomponent source types, having compositional similarities to A-type within-plate granites as well as to S- and I-type granites generated in an arc setting. In addition, the volcanic-hosted IOA and IOCG deposits occur within bimodal volcanic sequences, some of which have volcanic arc geochemical affinities, suggesting an extensional tectonic setting during volcanism prior to emplacement of the ore-forming systems.The Missouri iron orebodies are magmatic-related hydrothermal deposits that, when considered in aggregate, display a vertical zonation from high-temperature, magmatic ± hydrothermal IOA deposits emplaced at moderate depths (~1–2 km), to magnetite-dominant IOA veins and IOCG deposits emplaced at shallow

  3. Advanced Land Observing Satellite (ALOS) Phased Array Type L-Band Synthetic Aperture Radar (PALSAR) mosaic for the Kahiltna terrane, Alaska, 2007-2010

    Science.gov (United States)

    Cole, Christopher J.; Johnson, Michaela R.; Graham, Garth E.

    2015-01-01

    The U.S. Geological Survey (USGS) has initiated a multi-disciplinary study investigating the applicability of remote sensing technologies for geologic mapping and identification of prospective areas for base and precious metal deposits in remote parts of Alaska. The Kahiltna terrane in southwestern Alaska was selected for investigation because of its known mineral deposits and potential for additional mineral resources. An assortment of technologies is being investigated to aid in remote analysis of terrain, and includes imaging spectroscopy (hyperspectral remote sensing), high spatial resolution electro-optical imagery, and Synthetic Aperture Radar (SAR). However, there are significant challenges to applying imaging spectroscopy and electro-optical imagery technologies in this area because of the low solar angle for parts of the year, seasonal periods of darkness and snow cover, and the frequently cloudy weather that characterizes Alaska. Synthetic Aperture Radar (SAR) was selected because this technology does not rely on solar illumination and has all-weather capability.

  4. An autochthonous Avalonian basement source for the latest Ordovician Brenton Pluton in the Meguma terrane of Nova Scotia: U-Pb-Hf isotopic constraints and paleogeographic implications

    Science.gov (United States)

    Duncan Keppie, J.; Gregory Shellnutt, J.; Dostal, Jaroslav; Fraser Keppie, D.

    2018-04-01

    The Ediacaran-Ordovician Meguma Supergroup was thrust over Avalonia basement prior to the intrusion of post-Acadian, ca. 370 Ma, S-type granitic batholiths. This has led to two main hypotheses regarding the original location of the Meguma terrane, a continental rise prism bordering either NW Africa or Avalonia. On the other hand, the pre-Acadian, ca. 440 Ma Brenton pluton has yielded the following U/Pb LA-ICP-MS zircon data: (1) 448 ± 3 Ma population peak inferred to be the intrusive age and (2) ca. 550 and 700 Ma inherited ages common to both Avalonia and NW Africa. In contrast, Hf isotopic analyses of zircon yielded model ages ranging from 814 to 1127 Ma with most between 940 and 1040 Ma: such ages are typical of Avalonia and not NW Africa. The ages of the inherited zircons found within the Brenton pluton suggest that it was probably derived by partial melting of sub-Meguma, mid-crustal Avalonian rocks, upon which the Meguma Supergroup was deposited. Although Avalonia is commonly included in the peri-Gondwanan terranes off NW Africa or Amazonia, paleomagnetic data, faunal provinciality, and Hf data suggest that, during the Ediacaran-Early Cambrian, it was an island chain lying near the tropics (ca. 20-30 °S) and was possibly a continuation of the Bolshezemel volcanic arc accreted to northern Baltica during the Ediacaran Timanide orogenesis. This is consistent with the similar derital zircon population in the Ediacaran-Cambrian Meguma Supergroup and the Dividal Group in northeastern Baltica.

  5. What was the Paleogene latitude of the Lhasa terrane? A reassessment of the geochronology and paleomagnetism of Linzizong volcanic rocks (Linzhou basin, Tibet)

    Science.gov (United States)

    Huang, Wentao; Dupont-Nivet, Guillaume; Lippert, Peter C.; van Hinsbergen, Douwe J. J.; Dekkers, Mark J.; Waldrip, Ross; Ganerød, Morgan; Li, Xiaochun; Guo, Zhaojie; Kapp, Paul

    2015-03-01

    The Paleogene latitude of the Lhasa terrane (southern Tibet) can constrain the age of the onset of the India-Asia collision. Estimates for this latitude, however, vary from 5°N to 30°N, and thus, here, we reassess the geochronology and paleomagnetism of Paleogene volcanic rocks from the Linzizong Group in the Linzhou basin. The lower and upper parts of the section previously yielded particularly conflicting ages and paleolatitudes. We report consistent 40Ar/39Ar and U-Pb zircon dates of 52 Ma for the upper Linzizong, and 40Ar/39Ar dates ( 51 Ma) from the lower Linzizong are significantly younger than U-Pb zircon dates (64-63 Ma), suggesting that the lower Linzizong was thermally and/or chemically reset. Paleomagnetic results from 24 sites in lower Linzizong confirm a low apparent paleolatitude of 5°N, compared to the upper part ( 20°N) and to underlying Cretaceous strata ( 20°N). Detailed rock magnetic analyses, end-member modeling of magnetic components, and petrography from the lower and upper Linzizong indicate widespread secondary hematite in the lower Linzizong, whereas hematite is rare in upper Linzizong. Volcanic rocks of the lower Linzizong have been hydrothermally chemically remagnetized, whereas the upper Linzizong retains a primary remanence. We suggest that remagnetization was induced by acquisition of chemical and thermoviscous remanent magnetizations such that the shallow inclinations are an artifact of a tilt correction applied to a secondary remanence in lower Linzizong. We estimate that the Paleogene latitude of Lhasa terrane was 20 ± 4°N, consistent with previous results suggesting that India-Asia collision likely took place by 52 Ma at 20°N.

  6. Petrogenesis, U-Pb and Sm-Nd geochronology of the Furna Azul Migmatite: partial melting evidence during the San Ignacio Orogeny, Paragua Terrane, SW Amazon Craton

    Energy Technology Data Exchange (ETDEWEB)

    Nascimento, Newton Diego Couto do; Ruiz, Amarildo Salina; Pierosan, Ronaldo; Lima, Gabrielle Aparecida de; Matos, Joao Batista; Lafon, Jean-Michel; Moura, Candido Augusto Veloso, E-mail: newtongeologia@hotmail.com, E-mail: asruiz@gmail.com, E-mail: ronaldo.pierosan@yahoo.com.br, E-mail: gabilimagel@gmail.com, E-mail: lafonjm@ufpa.br, E-mail: prof.jmatos@gmail.com, E-mail: candido@ufpa.br [Universidade Federal do Para (GEOCIAM/UFPA), Belem, PA (Brazil). Instituto Nacional de Ciencia e Tecnologia de Geociencias da Amazonia

    2016-11-01

    The Furna Azul Migmatite is a ∼10 km{sup 2} complex located in Pontes e Lacerda city, Mato Grosso, Brazil. It belongs to Paragua Terrane, limit with Rio Alegre Terrane, southeast of San Ignacio Province, in Amazon Craton. It consists of transitional metatexites with amphibolite enclaves and dioritic injections. The rocks were divided in residuum rich and leucosome rich; both have three deformation phases marked by folded stromatic layers affected by spaced foliation and metamorphosed in amphibolite facies, represented by garnet, biotite, sillimanite, and by the clinopyroxene in the enclaves. The metamorphic retrograde to greenschist is marked by formation of chlorite, muscovite and prehnite. Residuum-rich metatexites show higher CaO and Na{sub 2}O contents, separating them from K{sub 2}O, Ba and Rb enriched transitional metatexites. U-Pb on zircon and Sm-Nd whole-rocks dating indicates that the residuum-rich metatexite crystallized at 1436 ± 11 Ma, with a T{sub DM} age of 1.90 Ga and ε{sub Nd(1.43)} of -0.54, whereas the dioritic injection crystallized at 1341,7 ± 17 Ma with a T{sub DM} age of 1.47 Ga and ε{sub Nd(1.34)} of 3.39. These results indicate that the Furna Azul Migmatite protolith was formed during the San Ignacio Orogeny and was reworked during the same orogeny, as basement for collisional to post-magmatic granites from Pensamiento Intrusive Suite. (author)

  7. Determinants of fish assemblage structure in Northwestern Great Plains streams

    Science.gov (United States)

    Mullen, J.A.; Bramblett, R.G.; Guy, C.S.; Zale, A.V.; Roberts, D.W.

    2011-01-01

    Prairie streams are known for their harsh and stochastic physical conditions, and the fish assemblages therein have been shown to be temporally variable. We assessed the spatial and temporal variation in fish assemblage structure in five intermittent, adventitious northwestern Great Plains streams representing a gradient of watershed areas. Fish assemblages and abiotic conditions varied more spatially than temporally. The most important variables explaining fish assemblage structure were longitudinal position and the proportion of fine substrates. The proportion of fine substrates increased proceeding upstream, approaching 100% in all five streams, and species richness declined upstream with increasing fine substrates. High levels of fine substrate in the upper reaches appeared to limit the distribution of obligate lithophilic fish species to reaches further downstream. Species richness and substrates were similar among all five streams at the lowermost and uppermost sites. However, in the middle reaches, species richness increased, the amount of fine substrate decreased, and connectivity increased as watershed area increased. Season and some dimensions of habitat (including thalweg depth, absolute distance to the main-stem river, and watershed size) were not essential in explaining the variation in fish assemblages. Fish species richness varied more temporally than overall fish assemblage structure did because common species were consistently abundant across seasons, whereas rare species were sometimes absent or perhaps not detected by sampling. The similarity in our results among five streams varying in watershed size and those from other studies supports the generalization that spatial variation exceeds temporal variation in the fish assemblages of prairie and warmwater streams. Furthermore, given longitudinal position, substrate, and stream size, general predictions regarding fish assemblage structure and function in prairie streams are possible. ?? American

  8. The earliest evidence for anatomically modern humans in northwestern Europe.

    Science.gov (United States)

    Higham, Tom; Compton, Tim; Stringer, Chris; Jacobi, Roger; Shapiro, Beth; Trinkaus, Erik; Chandler, Barry; Gröning, Flora; Collins, Chris; Hillson, Simon; O'Higgins, Paul; FitzGerald, Charles; Fagan, Michael

    2011-11-02

    The earliest anatomically modern humans in Europe are thought to have appeared around 43,000-42,000 calendar years before present (43-42 kyr cal BP), by association with Aurignacian sites and lithic assemblages assumed to have been made by modern humans rather than by Neanderthals. However, the actual physical evidence for modern humans is extremely rare, and direct dates reach no farther back than about 41-39 kyr cal BP, leaving a gap. Here we show, using stratigraphic, chronological and archaeological data, that a fragment of human maxilla from the Kent's Cavern site, UK, dates to the earlier period. The maxilla (KC4), which was excavated in 1927, was initially diagnosed as Upper Palaeolithic modern human. In 1989, it was directly radiocarbon dated by accelerator mass spectrometry to 36.4-34.7 kyr cal BP. Using a Bayesian analysis of new ultrafiltered bone collagen dates in an ordered stratigraphic sequence at the site, we show that this date is a considerable underestimate. Instead, KC4 dates to 44.2-41.5 kyr cal BP. This makes it older than any other equivalently dated modern human specimen and directly contemporary with the latest European Neanderthals, thus making its taxonomic attribution crucial. We also show that in 13 dental traits KC4 possesses modern human rather than Neanderthal characteristics; three other traits show Neanderthal affinities and a further seven are ambiguous. KC4 therefore represents the oldest known anatomically modern human fossil in northwestern Europe, fills a key gap between the earliest dated Aurignacian remains and the earliest human skeletal remains, and demonstrates the wide and rapid dispersal of early modern humans across Europe more than 40 kyr ago. ©2011 Macmillan Publishers Limited. All rights reserved

  9. Hydrogeochemistry and simulated solute transport, Piceance Basin, northwestern Colorado

    Science.gov (United States)

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

    1981-01-01

    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)

  10. 90-Sr in Milk in the North-Western Croatia

    International Nuclear Information System (INIS)

    Maracic, M.; Marovic, G.; Lokobauer, N.; Sencar, J.; Petroci, Lj.

    2003-01-01

    The program of radioactivity measurements and monitoring of the human environment in Croatia, carried out by the Radiation Protection Unit of the Institute for Medical Research and Occupational Heath in Zagreb, involve also investigations of radiostrontium in milk and milk products. Milk is a very important foodstuff and a critical food in respect to the presence and persistence of nuclides in the body. Because of its high calcium content, milk is used as a sensitive indicator for the presence of fission products in foods and in the environment. It is also an important route of entry of radiostrontium from fallout to man. Radiostrontium, a highly toxic radionuclide, is similar to calcium in its chemical behaviour, including its deposition in human bone. The paper describes investigation of 9 0S r activity in milk collected over the period of six year at two locations in the north-western part of the Republic of Croatia. 9 0S r was determined by extraction with tributyl phosphate. 9 0S r was measured on basis of radioactive balance with its decay product 9 0Y , counted by low background level anti-coincidence shielded GM counter. In the Republic of Croatia, milk consumption of approximately 100 L per year/person can potentially lead to the accumulation of significant radiation dose. The doses received from milk consumption are small, but owing to the long retention time of 9 0S r in bone which can be the basis for its potential hazard, 9 0S r level require continuous control and monitoring. Special emphasis should be given to children as the most vulnerable part of population. (author)

  11. Anther and isolated microspore culture of wheat lines from northwestern and eastern Europe

    DEFF Research Database (Denmark)

    Holme, I B; Olesen, A; Hansen, N J P

    1999-01-01

    Hexaploid wheat genotypes from north-western Europe show low responses to current anther culture techniques. This phenomenon was investigated on 145 north-western European wheat lines. Twenty-seven lines from eastern Europe were included to observe the response pattern of wheat from an area, where...... the technique has been used successfully. On average, eastern European wheat lines produced 3.6 green plants per 111 anthers, while only 1.4 green plants per 111 anthers were obtained in north-western European lines. This difference was due to the high capacity for embryo formation among the eastern European...... lines, while the ability to regenerate green plants was widespread in both germplasm groups. Isolated wheat microspore culture performed on 85 of these wheat lines gave an average 3.7-fold increase in green plants per anther compared with the anther culture response. The increased recovery of green...

  12. Nonlinearity and Fractal Properties of Climate Change during the Past 500 Years in Northwestern China

    Directory of Open Access Journals (Sweden)

    Shiquan Wan

    2016-01-01

    Full Text Available By using detrended fluctuation analysis (DFA, the present paper analyzed the nonlinearity and fractal properties of tree-ring records from two types of trees in northwestern China, and then we disclosed climate change characteristics during the past 500 years in this area. The results indicate that climate change in northwestern China displayed a long-range correlation (LRC, which can exist over time span of 100 years or longer. This conclusion provides a theoretical basis for long-term climate predictions. Combining the DFA results obtained from daily temperatures records at the Xi’an meteorological observation station, which is near the southern peak of the Huashan Mountains, self-similarities widely existed in climate change on monthly, seasonal, annual, and decadal timescales during the past 500 years in northwestern China, and this change was a typical nonlinear process.

  13. 75 FR 26786 - Notice of Public Meeting: Sierra Front-Northwestern Great Basin Resource Advisory Council, NV

    Science.gov (United States)

    2010-05-12

    ... 261A; 10-08807; MO 4500012081; TAS: 14X1109] Notice of Public Meeting: Sierra Front-Northwestern Great..., Bureau of Land Management (BLM) Sierra Front-Northwestern Great Basin Resource Advisory Council (RAC... discussion will include, but are not limited to: District Manager's reports on current program of work, Draft...

  14. Geographic information modeling of Econet of Northwestern Federal District territory on graph theory basis

    Science.gov (United States)

    Kopylova, N. S.; Bykova, A. A.; Beregovoy, D. N.

    2018-05-01

    Based on the landscape-geographical approach, a structural and logical scheme for the Northwestern Federal District Econet has been developed, which can be integrated into the federal and world ecological network in order to improve the environmental infrastructure of the region. The method of Northwestern Federal District Econet organization on the basis of graph theory by means of the Quantum GIS geographic information system is proposed as an effective mean of preserving and recreating the unique biodiversity of landscapes, regulation of the sphere of environmental protection.

  15. A Cambrian mixed carbonate-siliciclastic platform in SW Gondwana: evidence from the Western Sierras Pampeanas (Argentina) and implications for the early Paleozoic paleogeography of the proto-Andean margin

    Science.gov (United States)

    Ramacciotti, Carlos D.; Casquet, César; Baldo, Edgardo G.; Galindo, Carmen; Pankhurst, Robert J.; Verdecchia, Sebastián O.; Rapela, Carlos W.; Fanning, Mark

    2018-05-01

    The Western Sierras Pampeanas (WSP) of Argentina record a protracted geological history from the Mesoproterozoic assembly of the Rodinia supercontinent to the early Paleozoic tectonic evolution of SW Gondwana. Two well-known orogenies took place at the proto-Andean margin of Gondwana in the Cambrian and the Ordovician, i.e., the Pampean (545-520 Ma) and Famatinian (490-440 Ma) orogenies, respectively. Between them, an extensive continental platform was developed, where mixed carbonate-siliciclastic sedimentation occurred. This platform was later involved in the Famatinian orogeny when it underwent penetrative deformation and metamorphism. The platform apparently extended from Patagonia to northwestern Argentina and the Eastern Sierras Pampeanas, and has probable equivalents in SW Africa, Peru, and Bolivia. The WSP record the outer (deepest) part of the platform, where carbonates were deposited in addition to siliciclastic sediments. Detrital zircon U-Pb SHRIMP ages from clastic metasedimentary successions and Sr-isotope compositions of marbles from the WSP suggest depositional ages between ca. 525 and 490 Ma. The detrital zircon age patterns further suggest that clastic sedimentation took place in two stages. The first was sourced mainly from re-working of the underlying Neoproterozoic metasedimentary rocks and the uplifted core of the early Cambrian Pampean orogen, without input from the Paleoproterozoic Río de la Plata craton. Sediments of the second stage resulted from the erosion of the still emerged Pampean belt and the Neoproterozoic Brasiliano orogen in the NE with some contribution from the Río de la Plata craton. An important conclusion is that the WSP basement was already part of SW Gondwana in the early Cambrian, and not part of the exotic Precordillera/Cuyania terrane, as was previously thought.

  16. A juvenile subfossil crocodylian from Anjohibe Cave, Northwestern Madagascar

    Directory of Open Access Journals (Sweden)

    Joshua C. Mathews

    2016-09-01

    Full Text Available Madagascar’s subfossil record preserves a diverse community of animals including elephant birds, pygmy hippopotamus, giant lemurs, turtles, crocodiles, bats, rodents, and carnivorans. These fossil accumulations give us a window into the island’s past from 80,000 years ago to a mere few hundred years ago, recording the extinction of some groups and the persistence of others. The crocodylian subfossil record is limited to two taxa, Voay robustus and Crocodylus niloticus, found at sites distributed throughout the island. V. robustus is extinct while C. niloticus is still found on the island today, but whether these two species overlapped temporally, or if Voay was driven to extinction by competing with Crocodylus remains unknown. While their size and presumed behavior was similar to each other, nearly nothing is known about the growth and development of Voay, as the overwhelming majority of fossil specimens represent mature adult individuals. Here we describe a nearly complete juvenile crocodylian specimen from Anjohibe Cave, northwestern Madagascar. The specimen is referred to Crocodylus based on the presence of caviconchal recesses on the medial wall of the maxillae, and to C. niloticus based on the presence of an oval shaped internal choana, lack of rostral ornamentation and a long narrow snout. However, as there are currently no described juvenile specimens of Voay robustus, it is important to recognize that some of the defining characteristics of that genus may have changed through ontogeny. Elements include a nearly complete skull and many postcranial elements (cervical, thoracic, sacral, and caudal vertebrae, pectoral elements, pelvic elements, forelimb and hindlimb elements, osteoderms. Crocodylus niloticus currently inhabits Madagascar but is locally extinct from this particular region; radiometric dating indicates an age of ∼460–310 years before present (BP. This specimen clearly represents a juvenile based on the extremely small

  17. Pulsed remineralisation in the northwestern Mediterranean Sea: a hypothesis

    Science.gov (United States)

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

    2003-02-01

    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

  18. New evidence for Oligocene to Recent slip along the San Juan fault, a terrane-bounding structure within the Cascadia forearc of southern British Columbia, Canada

    Science.gov (United States)

    Harrichhausen, N.; Morell, K. D.; Regalla, C.; Lynch, E. M.

    2017-12-01

    Active forearc deformation in the southern Cascadia subduction zone is partially accommodated by faults in the upper crust in both Washington state and Oregon, but until recently, these types of active forearc faults have not been documented in the northern part of the Cascadia forearc on Vancouver Island, British Columbia. Here we present new evidence for Quaternary slip on the San Juan fault that indicates that this terrane-bounding structure has been reactivated since its last documented slip in the Eocene. Field work targeted by newly acquired hi-resolution lidar topography reveals a deformed debris flow channel network developed within colluvium along the central portion of the San Juan fault, consistent with a surface-rupturing earthquake with 1-2 m of offset since deglaciation 13 ka. Near the western extent of the San Juan fault, marine sediments are in fault contact with mélange of the Pandora Peak Unit. These marine sediments are likely Oligocene or younger in age, given their similarity in facies and fossil assemblages to nearby outcrops of the Carmanah Group sediments, but new dating using strontium isotope stratigraphy will confirm this hypothesis. If these sediments are part of the Carmanah Group, they occur further east and at a higher elevation than previously documented. The presence of Oligocene or younger marine sediments, more than 400 meters above current sea level, requires a substantial amount of Neogene rock uplift that could have been accommodated by slip on the San Juan fault. A preliminary analysis of fault slickensides indicates a change in slip sense from left-lateral to normal along the strike of the fault. Until further mapping and analysis is completed, however, it remains unclear whether this kinematic change reflects spatial and/or temporal variability. These observations suggest that the San Juan fault is likely part of a network of active faults accommodating forearc strain on Vancouver Island. With the recent discovery of

  19. A possible bedrock source for obsidian found in archeological sites in northwestern alaska.

    Science.gov (United States)

    Patton, W W; Miller, T P

    1970-08-21

    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.

  20. Impacts of Potential Oak Forest Change on Breeding Birds in Northwestern Arkansas

    Science.gov (United States)

    Douglas A. James

    2004-01-01

    Birds found on existing census routes in the Ozark region of northwestern Arkansas were used to predict avifaunal changes that could occur in the area due to oak-hickory forest degradation caused by red oak borer beetle infestations. The two census routes used passed through high elevation forests where red oaks thrive the best. Analysis showed that 21 bird species...

  1. West Nile virus isolated from a Virginia opossum (Didelphis virginiana) in northwestern Missouri, USA, 2012.

    Science.gov (United States)

    Bosco-Lauth, Angela; Harmon, Jessica R; Lash, R Ryan; Weiss, Sonja; Langevin, Stanley; Savage, Harry M; Godsey, Marvin S; Burkhalter, Kristen; Root, J Jeffrey; Gidlewski, Thomas; Nicholson, William L; Brault, Aaron C; Komar, Nicholas

    2014-10-01

    We describe the isolation of West Nile virus (WNV; Flaviviridae, Flavivirus) from blood of a Virginia opossum (Didelphis virginiana) collected in northwestern Missouri, USA in August 2012. Sequencing determined that the virus was related to lineage 1a WNV02 strains. We discuss the role of wildlife in WNV disease epidemiology.

  2. Popular and formal Islam, and supralocal relations : the Highlands of Northwestern Tunisia, 1800-1970

    NARCIS (Netherlands)

    Binsbergen, W.M.J.

    1979-01-01

    The present paper explores the interplay between local popular Islam and the repeated introduction of formal Islam in Khrumiria, North-western Tunisia, against the background of its social and political structure and the radical changes the latter underwent in the colonial and post-colonial era. The

  3. Elevated heat pump effects of dust aerosol over Northwestern China during summer

    Science.gov (United States)

    Tang, Yaoguo; Han, Yongxiang; Ma, Xiaoyan; Liu, Zhaohuan

    2018-05-01

    The Elevated Heat Pump (EHP) effect demonstrates a significant interaction between the aerosol climatic effect and the monsoon, both are important for climate research. In Northwestern China, the influence of EHP mechanism is still lacking in research. In this study, the EHP effects in Northwestern China are investigated by three sensitivity tests using a WRF-Chem model coupled with the Shao dust emission scheme. Results show that: 1) the anomalous circulation caused by dust aerosols are proved to the existence of EHP effect in Northwestern China; 2) three updrafts over the desert are transported eastward at high altitude and subside in Northeastern China, forming a complete secondary circulation with low-level easterly flow from Badain Jaran and Tengger to Taklimakan; 3) a northeasternerly anomaly flow from Northeastern China can affect the intensity of East Asian summer monsoon (EASM), and increase precipitation in the middle and lower reaches of the Yangtze River and decrease precipitation in Northeastern China. 4) We present a conceptual model of EHP in Northwestern China to provide a better understanding of the climatic effects of dust aerosols.

  4. Synchrony in the snowshoe hare cycle in Northwestern North America, 1970-2012

    Science.gov (United States)

    C.J. Krebs; K. Kielland; J.P Bryant; M. O' Donoghue; F. Doyle; C. McIntyre; D. DiFolco; N. Berg; S. Carriere; R. Boonstra; S. Boutin; A. J. Kenney; D. G. Reid; K. Bodony; J. Putera; H. K. Timm; T. Burke.

    2013-01-01

    Snowshoe hares (Lepus americanus Erxleben, 1777) fluctuate in 9–10 year cycles throughout much of their North American range. Regional synchrony has been assumed to be the rule for these cycles, so that hare populations in virtually all of northwestern North America have been assumed to be in phase. We gathered qualitative and quantitative data on...

  5. Influences of climate on fire regimes in montane forests of north-western Mexico

    Science.gov (United States)

    Carl N. Skinner; Jack H. Burk; Michael G. Barbour; Ernesto Franco-Vizcaino; Scott L. Stephens

    2008-01-01

    Aim To identify the influence of interannual and interdecadal climate variation on the occurrence and extent of fires in montane conifer forests of north-western Mexico. Location This study was conducted in Jeffrey pine (Pinus jeffreyi Grev. & Balf.)- dominated mixed-conifer...

  6. The first radiocarbon data of bone remains of mammoth faunal forms in northwestern Russia

    NARCIS (Netherlands)

    Nikonov, A. A.; Van der Plicht, J.; Kotlyakov, V.M.

    Unlike in the neighboring territories, the distribution and the period of habitation of late Pleistocene mammoth complex animals in the northwestern area of Russia had not been studied until recently. This article fills in this gap using the bone material from the Zoological Institute of the Russian

  7. Ground-water appraisal in northwestern Big Stone County, west-central Minnesota

    Science.gov (United States)

    Soukup, W.G.

    1980-01-01

    The development of ground water for irrigation in northwestern Big Stone County has not kept up with development in other irrigable areas of the State. This is due, in part, to the absence of extensive surficial aquifers and the difficulty in locating buried aquifers.

  8. Spatial trends of polyfluorinated compounds in guillemot (Uria aalge) eggs from North-Western Europe

    DEFF Research Database (Denmark)

    Löfstrand, Karin; Jörundsdóttir, Hrönn; Tomy, Gregg

    2008-01-01

    carboxylic acids (PFCAs) in guillemot (Uria aalge) eggs, collected in North-Western Europe, from Iceland, the Faroe Islands, Sweden and two locations in Norway. The highest concentrations of PFOS were found in samples from Sweden (mean 400 ng g(-1) wet weight (w.w.)), which were almost five times higher than...

  9. Connecting endangered brown bear subpopulations in the Cantabrian Range (north-western Spain)

    Science.gov (United States)

    M. C. Mateo-Sanchez; Samuel Cushman; S. Saura

    2014-01-01

    The viability of many species depends on functional connectivity of their populations through dispersal across broad landscapes. This is particularly the case for the endangered brown bear in north-western Spain, with a total population of about 200 individuals in two subpopulations that are separated by a wide gap with low permeability. Our goal in this paper...

  10. The Eel River, northwestern California; high sediment yields from a dynamic landscape

    Science.gov (United States)

    Thomas E. Lisle

    1990-01-01

    The Eel River draining the Coast Range of northwestern California has the highest recorded average suspended sediment yield per drainage area of any river of its size or larger unaffected by volcanic eruptions or active glaciers in the conterminous United States (1,720 t/km 2 yr from 9,390 km 2 ; Brown and Ritter, 1971).

  11. Modeling Tamarisk (Tamarix spp.) habitat and climate change effects in the northwestern United States

    Science.gov (United States)

    Becky K. Kerns; Bridgett J. Naylor; Michelle Buonopane; Catherine G. Parks; Brendan. Rogers

    2009-01-01

    Tamarisk species are shrubs or small trees considered by some to be among the most aggressively invasive and potentially detrimental exotic plants in the United States. Although extensively studied in the southern and interior west, northwestern (Oregon, Washington, and Idaho) distribution and habitat information for tamarisk is either limited or lacking. We obtained...

  12. Forest responses to climate change in the northwestern United States: ecophysiological foundations for adaptive management

    Science.gov (United States)

    Daniel J. Chmura; Paul D. Anderson; Glenn T. Howe; Constance A. Harrington; Jessica E. Halofsky; David L. Peterson; David C. Shaw; Brad J. St Clair

    2011-01-01

    Climate change resulting from increased concentrations of atmospheric carbon dioxide ([C02]) is expected to result in warmer temperatures and changed precipitation regimes during this century. In the northwestern U.S., these changes will likely decrease snowpack, cause earlier snowmelt, increase summer evapotranspiration, and increase the...

  13. Leech presence on Iberian Brown Frog, Rana iberica, (Amphibia: Anura: Ranidae from north-western Spain

    Directory of Open Access Journals (Sweden)

    César Ayres

    2008-12-01

    Full Text Available The authors describe a case of parasitism on Rana iberica by two species of leeches, Batracobdella sp. and Hirudo medicinalis, in a mountainous area of north-western Spain. Conservation implications of high parasite load on small and isolated populations are discussed.

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

    Science.gov (United States)

    Barnes, Sarah V.

    1994-01-01

    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)

  15. A new genus and species of Bythitidae (Teleostei: Ophidiiformes) from northwestern Australia

    DEFF Research Database (Denmark)

    Nielsen, Jørgen; Schwarzhans, Werner

    2011-01-01

    A new genus and species of bathyal bythitid fish (Teleostei: Ophidiiformes) is described based on a single specimen caught at a depth of 392 m in the Timor Sea off the coast of northwestern Australia. Timorichthys disjunctus gen. nov., sp. nov. differs from all other bythitid genera by the position...

  16. Benthic nutrient cycling and diagenetic pathways in the North-western Black Sea

    NARCIS (Netherlands)

    Friedrich, J.; Dinkel, C.; Friedl, G.; Pimenov, N.; Wijsman, J.W.M.; Gomoiu, M-T.; Cociasu, A.; Popa, L.; Wehrli, B.

    2002-01-01

    Benthic fluxes of nutrients and metals were measured in the coastal zone of the north-western Black Sea, which is influenced by the Danube and Dniestr rivers. The results from the benthic flux chambers deployed during two EROS 21 cruises in summer 1995 and in spring 1997 yield information on benthic

  17. Reconstruction of burial history, temperature, source rock maturity and hydrocarbon generation in the northwestern Dutch offshore

    NARCIS (Netherlands)

    Abdul Fattah, R.; Verweij, J.M.; Witmans, N.; Veen, J.H. ten

    2012-01-01

    3D basin modelling is used to investigate the history of maturation and hydrocarbon generation on the main platforms in the northwestern part of the offshore area of the Netherlands. The study area covers the Cleaverbank and Elbow Spit Platforms. Recently compiled maps and data are used to build the

  18. Assessing malaria transmission in a low endemicity area of north-western Peru

    DEFF Research Database (Denmark)

    Rosas-Aguirre, Angel; Llanos-Cuentas, Alejandro; Speybroeck, Niko

    2013-01-01

    Where malaria endemicity is low, control programmes need increasingly sensitive tools for monitoring malaria transmission intensity (MTI) and to better define health priorities. A cross-sectional survey was conducted in a low endemicity area of the Peruvian north-western coast to assess the MTI u...

  19. Miocene fish faunas from the northwestern Amazonia basin (Colombia, Peru, Brazil) with evidence of marine incursions

    NARCIS (Netherlands)

    Monsch, KA

    1998-01-01

    New evidence indicates marine influences during the Miocene in the northwestern Amazonia basin. This is the first major survey of the ichthyofauna from this area in the Miocene. Fossil fish remains from taxa such as the Dasyatoidea, Myliobatoidea, Characiformes, Siluriformes and Sciaenidae are

  20. Restoring dry and moist forests of the inland northwestern United States [Chapter 23

    Science.gov (United States)

    Theresa B. Jain; Russell T. Graham

    2015-01-01

    The complex topography of the Inland Northwestern United States (58.4 million ha) interacts with soils and a highly variable climate to provide a mosaic of dry and moist mixed conifer forest settings. Approximately 20% of the area is covered by dry forests dominated by Pinus ponderosa, Pseudotsuga menziesii and contains a diversity of lower vegetation ranging from a...

  1. CRED Gridded Bathymetry of Nihoa Island (100-025) in the Northwestern Hawaiian Islands

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — File 100-025b is a 60-m ASCII grid of depth data collected near Nihoa Island in the Northwestern Hawaiian Islands as of May 2003. This grid has been produced as part...

  2. CRED Gridded Bathymetry of Raita Bank (100-009), in the Northwestern Hawaiian Islands

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — File 100-009b is a 60-m ASCII grid of depth data collected near Raita Bank in the Northwestern Hawaiian Islands as of May 2003. This grid has been produced as part...

  3. CRED Gridded Bathymetry of Northwest Gardner Pinnacles (100-011) in the Northwestern Hawaiian Islands

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — File 100-011b is a 60-m ASCII grid of depth data collected near Kure Atoll in the Northwestern Hawaiian Islands as of May 2003. This grid has been produced as part...

  4. CRED Gridded Bathymetry near Laysan Island (100-006), Northwestern Hawaiian Islands

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — File 100-006b is a 60-m ASCII grid of depth data collected near Laysan Island in the Northwestern Hawaiian Islands as of May 2003. This grid has been produced as...

  5. CRED Gridded Bathymetry of French Frigate Shoals (100-019) in the Northwestern Hawaiian Islands

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — File 100-019b is a 60-m ASCII grid of depth data collected near French Frigate Shoals in the Northwestern Hawaiian Islands as of May 2003. This grid has been...

  6. CRED Gridded Bathymetry near Midway Atoll (100-102), Northwestern Hawaiian Islands

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — File 100-102b is a 60-m ASCII grid of depth data collected near Midway Atoll in the Northwestern Hawaiian Islands as of May 2003. This grid has been produced as part...

  7. CRED Gridded Bathymetry of East Gardner Pinnacles (100-016) in the Northwestern Hawaiian Islands

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — File 100-016b is a 60-m ASCII grid of depth data collected near E Gardner Pinnacles in the Northwestern Hawaiian Islands as of May 2003. This grid has been produced...

  8. CRED Gridded Bathymetry near Northampton Seamounts to West Laysan Island (100-005) Northwestern Hawaiian Islands

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — File 100-005b is a 60-m ASCII grid of depth data collected near Kure Atoll in the Northwestern Hawaiian Islands as of May 2003. This grid has been produced as part...

  9. CRED Gridded Bathymetry of Northeast Gardner Pinnacles (100-013) in the Northwestern Hawaiian Islands

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — File 100-013b is a 60-m ASCII grid of depth data collected near NE Gardner Pinnacles in the Northwestern Hawaiian Islands as of May 2003. This grid has been produced...

  10. CRED Gridded Bathymetry of West St. Rogatien Bank (100-017) in the Northwestern Hawaiian Islands

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — File 100-017b is a 60-m ASCII grid of depth data collected near Kure Atoll in the Northwestern Hawaiian Islands as of May 2003. This grid has been produced as part...

  11. CRED Gridded Bathymetry of Southeast Maro Reef (100-010) in the Northwestern Hawaiian Islands

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — File 100-010b is a 60-m ASCII grid of depth data collected near SE Maro Reef in the Northwestern Hawaiian Islands as of May 2003. This grid has been produced as part...

  12. CRED Gridded Bathymetry near Maro Reef (100-007), Northwestern Hawaiian Islands

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — File 100-007b is a 60-m ASCII grid of depth data collected near Maro Reef in the Northwestern Hawaiian Islands as of May 2003. This grid has been produced as part of...

  13. CRED Gridded Bathymetry of East Necker Seamount (100-023) in the Northwestern Hawaiian Islands

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — File 100-023b is a 60-m ASCII grid of depth data collected near E. Necker Seamount in the Northwestern Hawaiian Islands as of May 2003. This grid has been produced...

  14. CRED Gridded Bathymetry of Southwest Gardner Pinnacles (100-012) in the Northwestern Hawaiian Islands

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — File 100-012b is a 60-m ASCII grid of depth data collected near SW Gardner Pinnacles in the Northwestern Hawaiian Islands as of May 2003. This grid has been produced...

  15. CRED Gridded Bathymetry near Lisianski Island (100-001), Northwestern Hawaiian Islands

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — File 100-001b is a 60-m ASCII grid of depth data collected near Lisianski Island in the Northwestern Hawaiian Islands as of May 2003. This grid has been produced as...

  16. CRED Gridded Bathymetry near Lisianski Island and Pioneer Bank (100-002), Northwestern Hawaiian Islands

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — File 100-002b is a 60-m ASCII grid of depth data collected near Lisianski Island and Pioneer Bank in the Northwestern Hawaiian Islands as of May 2003. This grid has...

  17. CRED Gridded Bathymetry of Necker Island (100-021) in the Northwestern Hawaiian Islands

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — File 100-021b is a 60-m ASCII grid of depth data collected near Necker Island in the Northwestern Hawaiian Islands as of May 2003. This grid has been produced as...

  18. Oligocene terrestrial strata of northwestern Ethiopia : a preliminary report on paleoenvironments and paleontology

    Science.gov (United States)

    Bonnie F. Jacobs; Neil Tabor; Mulugeta Feseha; Aaron Pan; John Kappelman; Tab Rasmussen; William Sanders; Michael Wiemann; Jeff Crabaugh; Juan Leandro Garcia Massini

    2005-01-01

    The Paleogene record of Afro-Arabia is represented by few fossil localities, most of which are coastal. Here we report sedimentological and paleontological data from continental Oligocene strata in northwestern Ethiopia. These have produced abundant plant fossils and unique assemblages of vertebrates, thus filling a gap in what is known of Paleogene interior Afro-...

  19. Anatomy of a Permian Erg sequence: the De La Cuesta Formation (northwestern Argentina)

    International Nuclear Information System (INIS)

    Spalletti, L.; Limarino, C.; Colombo, F.

    2010-01-01

    This work is about the Permian red beds of the La Cuesta Formation (Sierra de Narvaez, northwestern Argentina) which is composed of sandstones associated with mud stones and subordinate conglomerates. The sediments obtained from the interaction between aeolian and ephemeral fluvial systems, are represented by aeolian dune, dry aeolian inter dune and aeolian sand sheet, mud flat, wet aeolian inter dune, and fluvial deposits

  20. Climate change vulnerabilities and adaptation options for forest vegetation management in the northwestern USA

    Science.gov (United States)

    Jessica Halofsky; David Peterson

    2016-01-01

    Recent vulnerability assessments, conducted in diverse regions in the northwestern United States, indicate that many commonalities exist with respect to projected vulnerabilities to climate change. Dry forests are projected to have significant changes in distribution and abundance of species, partially in response to higher temperature and lower soil moisture, but...

  1. Transition in the Cause of Fever from Malaria to Dengue, Northwestern Ecuador, 1990–2011

    Science.gov (United States)

    Cifuentes, Sara G.; Trostle, James; Trueba, Gabriel; Milbrath, Meghan; Baldeón, Manuel E.; Coloma, Josefina

    2013-01-01

    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

  2. The intention of North-Western Ethiopian dairy farmers to control mastitis

    NARCIS (Netherlands)

    Mekonnen, Sefinew Alemu; Koop, Gerrit; Lam, Theo J G M; Hogeveen, Henk

    2017-01-01

    Understanding the intentions of dairy farmers towards mastitis control is important to design effective udder health control programs. We used the Theory of Planned Behavior (TPB) to explore the intentions of North-Western Ethiopian dairy farmers towards implementing non-specified mastitis control

  3. Diel and seasonal movements by adult Sacramento pikeminnow (Ptychocheilus grandis) in the Eel River, northwestern California

    Science.gov (United States)

    Bret C. Harvey; Rodney J. Nakamoto

    1999-01-01

    Abstract - In late summer and fall, radio-tagged adult Sacramento pike-minnow (Ptychocheilus grandis) at three sites in the Eel River of northwestern California moved more at night than during the day. Fish moved up to 535 m at night and returned to their original positions the following morning. Adult Sacramento pikeminnow at all sites occupied only pools during the...

  4. Diagnosis of Annosus Root Disease in Mixed Conifer Forests in the Northwestern United States

    Science.gov (United States)

    Craig L. Schmitt

    1989-01-01

    Recognizing annosus root disease affecting conifers in northwestern United States forests is discussed. Field diagnosis can bemade by observing characteristic stand patterns, wood stain and decay, ectotrophic mycelium, and sporophores. Most seriously affected trees include hemlocks, grand fir, white fir and Pacific silver fir. Ponderosa pine and other true firs may...

  5. Rb-Sr whole-rock and mineral ages, K-Ar, 40Ar/39Ar, and U-Pb mineral ages, and strontium, lead, neodymium, and oxygen isotopic compositions for granitic rocks from the Salinian Composite Terrane, California:

    Science.gov (United States)

    Kistler, R.W.; Champion, D.E.

    2001-01-01

    This report summarizes new and published age and isotopic data for whole-rocks and minerals from granitic rocks in the Salinian composite terrane, California. Rubidium-strontium whole-rock ages of plutons are in two groups, Early Cretaceous (122 to 100 Ma) and Late Cretaceous (95 to 82 Ma). Early Cretaceous plutons occur in all granitic rock exposures from Bodega Head in the north to those from the Santa Lucia and Gabilan Ranges in the central part of the terrane. Late Cretaceous plutons have been identified in the Point Reyes Peninsula, the Santa Lucia and the Gabilan Ranges, and in the La Panza Range in the southern part of the terrane. Ranges of initial values of isotopic compositions are 87Sr/86Sr, 0.7046-0.7147, δ18O, +8.5 to +12.5 per mil, 206Pb/204Pb, 18.901-19.860, 207Pb/204Pb, 15.618-15.814, 208Pb/204Pb, 38.569- 39.493, and εNd, +0.9 to -8.6. The initial 87Sr/86Sr=0.706 isopleth is identified in the northern Gabilan Range and in the Ben Lomond area of the Santa Cruz Mountains, in Montara Mountain, in Bodega Head, and to the west of the Farallon Islands on the Cordell Bank. This isotopic boundary is offset about 95 miles (160km) by right-lateral displacements along the San Gregorio-Hosgri and San Andreas fault systems.

  6. North-Western Palaearctic species of Pristiphora (Hymenoptera, Tenthredinidae

    Directory of Open Access Journals (Sweden)

    Marko Prous

    2017-09-01

    Full Text Available North-Western Palaearctic species of Pristiphora Latreille, 1810 are revised. Altogether, 90 species are treated, two of which are described as new: P. caraganae Vikberg & Prous, sp. n. from Finland and P. dedeara Liston & Prous, sp. n. from Germany. Host plant of P. caraganae is Caragana arborescens Lam. Pristiphora dasiphorae (Zinovjev, 1993 (previously known from East Palaearctic and P. cadma Wong & Ross, 1960 (previously known from North America are recorded for the first time from Europe. Nematus nigricans Eversmann, 1847 [= Pristiphora nigricans (Eversmann, 1847, comb. n.], N. breviusculus Eversmann, 1847 [= Euura melanocephalus (Hartig, 1837], and N. caudalis Eversmann, 1847 [= E. caudalis (Eversmann, 1847, comb. n.] are removed from synonymy with P. pallidiventris (Fallén, 1808, N. paralellus Hartig, 1840 [= P. paralella (Hartig, 1840, comb. n.] is removed from synonymy with P. bufo (Brischke, 1883, and P. mesatlantica Lacourt, 1976 is removed from synonymy with P. insularis Rohwer, 1910. The following 29 new synonymies are proposed: P. nigropuncticeps Haris, 2002, syn. n. with P. albitibia (Costa, 1859; Lygaeonematus karvoneni Lindqvist, 1952, syn. n. with P. alpestris (Konow, 1903; P. (P. anivskiensis Haris, 2006, syn. n. with P. appendiculata (Hartig, 1837; Nematus canaliculatus Hartig, 1840, syn. n with P. carinata (Hartig, 1837; P. nigrogroenblomi Haris, 2002, syn. n. with P. cincta Newman, 1837; Tenthredo flavipes Zetterstedt, 1838, syn. n., Nematus congener W.F. Kirby, 1882, syn. n., and P. thomsoni Lindqvist, 1953, syn. n. with P. dochmocera (Thomson, 1871; P. atrata Lindqvist, 1975, syn. n. with P. friesei (Konow, 1904; P. gelida Wong, 1968, syn. n. with P. frigida (Boheman, 1865; Pachynematus nigricorpus Takagi, 1931, syn. n. with P. laricis (Hartig, 1837; Nematus (Pikonema piceae Zhelochovtsev in Zhelochovtsev and Zinovjev, 1988, syn. n. and P. (P. hoverlaensis Haris, 2001, syn. n. with P. leucopodia (Hartig, 1837; Mesoneura

  7. Tectonostratigraphic reconstruction Cretaceous volcano-sedimentary in the northwestern Andes: from extensional tectonics to arc accretion.

    Science.gov (United States)

    Zapata, S.; Patino, A. M.; Cardona, A.; Mejia, D.; Leon, S.; Jaramillo, J. S.; Valencia, V.; Parra, M.; Hincapie, S.

    2014-12-01

    Active continental margins characterized by continuous convergence experienced overimposed tectonic configurations that allowed the formation of volcanic arcs, back arc basins, transtensional divergent tectonics or the accretion of exotic volcanic terranes. Such record, particularly the extensional phases, can be partially destroyed and obscure by multiple deformational events, the accretion of exotic terranes and strike slip fragmentation along the margin. The tectonic evolution of the northern Andes during the Mesozoic is the result of post Pangea extension followed by the installation of a long-lived Jurassic volcanic arc (209 - 136 ma) that apparently stops between 136 Ma and 110 Ma. The Quebradagrande Complex has been define as a single Lower Cretaceous volcano-sedimentary unit exposed in the western flank of the Central Cordillera of the Colombian Andes that growth after the Late Jurassic to Early Cretaceous magmatic hiatus. The origin of this unit have been related either to an oceanic volcanic arc or a marginal basin environment. The existence of such contrasting models reflect the regional perspective followed in published studies and the paucity of detail analysis of the volcano-sedimentary sequences.We integrate multiple approaches including structural mapping, stratigraphy, geochemistry, U-Pb provenance and geochronology to improve the understanding of this unit and track the earlier phases of accumulation that are mask on the overimposed tectonic history. Our preliminary results suggest the existence of different volcano-sedimentary units that accumulated between 100 Ma and 82 Ma.The older Lower Cretaceous sequences was deposited over Triassic metamorphic continental crust and include a upward basin deepening record characterized by thick fan delta conglomerates, followed by distal turbidites and a syn-sedimentary volcanic record at 100 ma. The other sequence include a 85 - 82 Ma fringing arc that was also formed close to the continental margin or

  8. Maps of Shallow-water Banks in the Northwestern Hawaiian Islands Derived from Moderate Resolution Landsat Satellite Imagery

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Shallow-water (generally, less than 30 meters) bank areas in the Northwestern Hawaiian Islands were identified using semi-automated image analysis of Landsat 7 ETM+...

  9. Influenza-A viruses in ducks in northwestern Minnesota: fine scale spatial and temporal variation in prevalence and subtype diversity

    Data.gov (United States)

    Department of the Interior — Waterfowl from northwestern Minnesota were sampled by cloacal swabbing for Avian Influenza Virus (AIV) from July – October in 2007 and 2008. AIV was detected in 222...

  10. CRED 60 m Gridded bathymetry and IKONOS estimated depths of UTM Zone 2, Northwestern Hawaiian Islands, USA (Arc ASCII format)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Gridded bathymetry and IKONOS estimated depths of the shelf and slope environments of the Northwestern Hawaiian Islands, USA within UTM Zone 2. Bottom coverage was...

  11. 2006 Reson 8101ER Multibeam Sonar Data from Cruise AHI-06-12 - Brooks Bank, Northwestern Hawaiian Islands

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Reson 8101ER multibeam Data were collected between 13-15 October 2006 aboard NOAA Survey Launch Acoustic Habitat Investigator (AHI) Brooks Banks in the Northwestern...

  12. CRED 60m Gridded bathymetry and IKONOS estimated depths of UTM Zone 3, Northwestern Hawaiian Islands, USA (Arc ASCII format)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Gridded bathymetry and IKONOS estimated depths of the shelf and slope environments of the Northwestern Hawaiian Islands, USA within UTM Zone 3. Bottom coverage was...

  13. The Park Volcanics Group : field relations of an igneous suite emplaced in the Triassic-Jurassic Murihiku Terrane, South Island, New Zealand

    International Nuclear Information System (INIS)

    Coombs, D.S.; Cook, N.D.J.; Campbell, J.D.

    1992-01-01

    Park Volcanics Group is proposed for igneous rocks, either shallow intrusive or extrusive, emplaced in the Murihiku Terrane during Triassic-Jurassic times. The term replaces Park Intrusives of Mutch, some members of which are shown to be extrusive rather than intrusive. Formation status within the group is given to Gowan Andesite and Pinney Volcanics (new names) in western Southland, Glenham Porphyry in eastern Southland, and Barnicoat Andesite (new) in the Richmond area, Nelson. Gowan Andesite is a porphyritic feldspar two-pyroxene andesite with a glassy or microcrystalline groundmass. A suite of low-grade metavolcanic rocks which forms the main mass of Malakoff Hill and which has formerly been included in the 'Park Intrusives' is here excluded and ascribed to the Takitimu Group; representative chemical data are given. Glenham Porphyry is typically a porphyritic feldspar two-pyroxene andesite texturally similar to the Gowan Andesite but with significant geochemical differences. Two volumetrically minor members are recognised, Habukinini Trachydacite and Kenilworth Rhyolite. In the north of its outcrop area, Glenham Porphyry is emplaced on or into Late Triassic terrestrial beds; in the middle it overlies Kaihikuan (Middle Triassic) and is overlain by Otapirian (latest Triassic) marine beds; and in the southeast it is directly overlain by Ururoan (late Early to early Middle Jurassic) conglomerates and marine sandstones. Pinney Volcanics are restricted to a very few, probably one, massive conglomeratic horizon in the Oretian Stage. The commonest rock type is a two-pyroxene trachydacite, modified by very-low-grade burial metamorphism. Auto-brecciation is characteristic and rock types change over short distances. Hornblende-rich variants occur as well as more felsic varieties including rhyolite ignimbrite. These may have been erupted onto a bouldery floodplain or shallow-marine surface, but alternatively may have been mass-emplaced by debris avalanche resulting from

  14. Paleoproterozoic (ca. 1.8 Ga) arc magmatism in the Lützow-Holm Complex, East Antarctica: Implications for crustal growth and terrane assembly in erstwhile Gondwana fragments

    Science.gov (United States)

    Takahashi, Kazuki; Tsunogae, Toshiaki; Santosh, M.; Takamura, Yusuke; Tsutsumi, Yukiyasu

    2018-05-01

    The Lützow-Holm Complex (LHC) of East Antarctica forms a part of the latest Neoproterozoic-Cambrian high-grade metamorphic segment of the East African-Antarctic Orogen. Here we present new petrological, geochemical, and zircon U-Pb geochronological data on meta-igneous rocks from four localities (Austhovde, Telen, Skallevikshalsen, and Skallen) in the LHC, and evaluate the regional Paleoproterozoic (ca. 1.8 Ga) arc magmatism in this terrane for the first time. The geochemical features reveal a volcanic-arc affinity for most of the meta-igneous rocks from Austhovde and Telen, suggesting that the protoliths of these rocks were derived from felsic to mafic arc magmatic rocks. The protoliths of two mafic granulites from Austhovde are inferred as non-volcanic-arc basalt such as E-MORB, suggesting the accretion of remnant oceanic lithosphere together with the volcanic-arc components during the subduction-collision events. The weighted mean 206Pb/238U ages of the dominant population of magmatic zircons in felsic orthogneisses from Austhovde and Telen show 1819 ± 19 Ma and 1830 ± 10 Ma, respectively, corresponding to Paleoproterozoic magmatic event. The magmatic zircons in orthogneisses from other two localities yield upper intercept ages of 1837 ± 54 Ma (Skallevikshalsen), and 1856 ± 37 Ma and 1854 ± 45 Ma (Skallen), which also support Paleoproterozoic magmatism. The earlier thermal events during Neoarchean to Early Paleoproterozoic are also traced by 206Pb/238U ages of xenocrystic zircons in the felsic orthogneisses from Austhovde (2517 ± 17 Ma and 2495 ± 15 Ma) and Telen (2126 ± 16 Ma), suggesting partial reworking of the basement of a 2.5 Ga microcontinent during ca. 1.8 Ga continental-arc magmatism. The timing of peak metamorphism is inferred to be in the range of 645.6 ± 10.4 to 521.4 ± 12.0 Ma based on 206Pb/238U weighted mean ages of metamorphic zircon grains. The results of this study, together with the available magmatic ages as well as geophysical and

  15. What can the Cretaceous-to-present latitude history of the Lhasa terrane tell us about plate-scale deformation in the Tibetan-Himalayan orogen? (Invited)

    Science.gov (United States)

    Lippert, P. C.; Van Hinsbergen, D. J.; Dupont-Nivet, G.; Huang, W.

    2013-12-01

    Published paleomagnetic data from well-dated sedimentary and volcanic rocks from the Lhasa terrane have been re-evaluated in a statistically consistent framework to assess the latitude history of southern Tibet from ~110 Ma to the present. We apply a methodology similar to the one used by the Time-Averaged geomagnetic Field Initiative to each paleomagnetic data set to establish coherency within and between paleomagnetic data from Tibet (see Session T023 for more details). Moreover, we use only sedimentary data that have been evaluated for and, where necessary, corrected for sedimentary inclination shallowing. The resulting apparent polar wander path (APWP) shows that the southern margin of the Lhasa terrane at the longitudes of Nepal remained at 20×4°N latitude from ~110 to at least 50 Ma and subsequently drifted northward to its present latitude of 29°N. This latitude history provides a paleomagnetically-determined collision age between the Tibetan Himalaya and the southern margin of Asia that is 49.5×4.5 Ma at 21×4° N latitude. The paleomagnetic age and latitude of this collision may be a few millions of years earlier and ~2° lower if estimates for shortening within the suture zone are considered. When compared to the global APWP of Torsvik et al. (2012) in Eurasian coordinates, the Lhasa APWP indicates that at most 1100×560 km of post-50 Ma India-Asia convergence was partitioned into Asian lithosphere. The lower bound of these paleomagnetic estimates is consistent with the magnitude of upper crustal shortening within Asia calculated from orogen-scale geological reconstructions. An implication is that 1700×560 km or more post-50 Ma India-Asia convergence was partitioned into Greater India. Paleomagnetic data from the Tibetan Himalaya are consistent with >2000 km of extension of Greater Indian lithosphere after break-up from Gondwana but prior to collision with the southern margin of Asia. Cenozoic subduction of this Cretaceous extensional basin following

  16. Tularemia Outbreaks and Common Vole (Microtus arvalis) Irruptive Population Dynamics in Northwestern Spain, 1997-2014.

    Science.gov (United States)

    Luque-Larena, Juan José; Mougeot, François; Roig, Dolors Vidal; Lambin, Xavier; Rodríguez-Pastor, Ruth; Rodríguez-Valín, Elena; Anda, Pedro; Escudero, Raquel

    2015-09-01

    During the last decades, large tularemia outbreaks in humans have coincided in time and space with population outbreaks of common voles in northwestern Spain, leading us to hypothesize that this rodent species acts as a key spillover agent of Francisella tularensis in the region. Here, we evaluate for the first time a potential link between irruptive vole numbers and human tularemia outbreaks in Spain. We compiled vole abundance estimates obtained through live-trapping monitoring studies and official reports of human tularemia cases during the period 1997-2014. We confirm a significant positive association between yearly cases of tularemia infection in humans and vole abundance. High vole densities during outbreaks (up to 1000 voles/hectare) may therefore enhance disease transmission and spillover contamination in the environment. If this ecological link is further confirmed, the apparent multiannual cyclicity of common vole outbreaks might provide a basis for forecasting the risk of tularemia outbreaks in northwestern Spain.

  17. Fukushima-derived radiocesium in the northwestern Pacific Ocean in February 2012

    International Nuclear Information System (INIS)

    Kumamoto, Yuichiro; Murata, Akihiko; Kawano, Takeshi; Aoyama, Michio

    2013-01-01

    We measured radiocesium ( 134 Cs and 137 Cs) in seawaters collected at stations in the northwestern Pacific Ocean in February 2012. Activity concentration of Fukushima-derived radiocesium was highest in the transition area between the subarctic and subtropical regions, which was due to the direct discharge. The direct discharged radiocesium was transported southwardly across the Kuroshio Extension along isopycnal mixing. More than 80% of the Fukushima-derived radiocesium at stations both in the transition area and subtropical region was derived from the direct discharge. - Highlights: • Fukushima-derived radiocesium was found in the northwestern Pacific in February 2012. • The highest activity concentration in the transition area was due to the direct discharge. • Direct discharged radiocesium was conveyed southwardly across the Kuroshio Current. • More than 80% of Fukushima-derived radiocesium was derived from the direct discharge

  18. Late Triassic porphyritic intrusions and associated volcanic rocks from the Shangri-La region, Yidun terrane, Eastern Tibetan Plateau: Adakitic magmatism and porphyry copper mineralization

    Science.gov (United States)

    Wang, Bai-Qiu; Zhou, Mei-Fu; Li, Jian-Wei; Yan, Dan-Ping

    2011-11-01

    Early Mesozoic porphyritic intrusions in the Shangri-La region, southern Yidun terrane, SW China, are spatially associated with andesites and dacites. These intrusions are composed of diorite and quartz diorite, and are closely related to copper mineralization. LA-ICP-MS zircon U-Pb ages of the intrusions range from 230 to 215 Ma. The associated andesites and dacites are interlayered with slates and sandstones and have ages of around 220 Ma. All of the intrusive and extrusive rocks have similar, highly fractionated REE patterns and high La/Yb (13-49) ratios with no prominent Eu anomalies. They display pronounced negative Nb-Ta and Ti anomalies on primitive mantle-normalized spidergrams. Their SiO2 contents range from 56.6 to 67.1 wt.%, Al2O3 from 14.2 to 17.4 wt.% and MgO from1.9 to 4.2 wt.%. All the rocks have high Sr (258-1980 ppm), and low Y (13-21 ppm) with high Sr/Y ratios (29-102). These features suggest that both the volcanic rocks and porphyritic intrusions were derived from adakitic magmas. They have similar initial 87Sr/86Sr ratios (0.7058 to 0.7077) and εNd (- 1.88 to - 4.93) values, but belong to high silica (HSA) and low silica adakitic rocks (LSA). The HSA represent an early stage of magmatism (230 to 215 Ma) and were derived from oceanic slab melts with limited interaction with the overlying mantle wedge during ascent. At 215 Ma, more extensive interaction produced the LSA. We propose that the early adakitic magmas (HSA) formed by flat subduction leading to melting of oceanic slab, whereas subsequent slab break-off caused the significant interaction between slab melts and the mantle wedge and thus the generation of the later adakitic magmas (LSA).

  19. Geology, petrology, U-Pb (SHRIMP) geochronology of the Morrinhos granite - Paragua terrane, SW Amazonian craton: implications for the magmatic evolution of the San Ignacio orogeny

    Energy Technology Data Exchange (ETDEWEB)

    Franca, Ohana; Ruiz, Amarildo Salina; Sousa, Maria Zelia Aguiar de, E-mail: ohana.geo@gmail.com, E-mail: asruiz@gmail.com, E-mail: mzaguiar@terra.com.br [Universidade Federal de Mato Grosso (UFMT), Cuiaba, MT (Brazil). Instituto de Ciencias Exatas e da Terra. Dept. de Geologia Geral; Batata, Maria Elisa Froes, E-mail: elisabatata@bol.com.br [Universidade Federal de Mato Grosso (UFMT), Cuiaba, MT (Brazil). Grupo de Pesquisa em Evolucao Crustal e Tectonica; Lafon, Jean-Michel [Universidade Federal do Para (GEOCIAM/UFPA), Belem, PR (Brazil). Inst. Nacional de Cencia e Tecnologia de Geociencias da Amazonia

    2014-09-15

    Morrinhos granite is a batholith body that is slightly elongated in the NNW direction and approximately 1,140 km{sup 2} long; it is located in the municipality of Vila Bela da Santissima Trindade of the state of Mato Grosso, Brazil, in the Paragua Terrane, Rondonian-San Ignacio Province, in the SW portion of the Amazonian Craton. This intrusion displays a compositional variation from tonalite to monzogranite, has a medium to coarse inequigranular texture and is locally porphyritic; biotite is the predominant mafic in one of the facies, and hornblende is predominant in the other, with both metamorphosed into the green schist facies. The studied rocks characterize an intermediate to acidic sequence that was formed by a subalkaline magmatism; the series is alkali-calcic to metaluminous to slightly peraluminous, and the rocks evolved through fractioned crystallization mechanisms. The structural data show two deformation phases represented by penetrative foliation (S{sub 1}) and open folds (D{sub 2}), and both phases were most likely related to the San Ignacio Orogeny. The geochronological (U-Pb SHRIMP) and isotopic (Sm-Nd) investigations of these rocks indicated a crystallization age of 1350±12Ma, T{sub DM} of approximately 1.77 Ga and εNd{sub (1.35}) with a negative value of -2.57, suggesting that their generation was related to a partial melting process of a Paleoproterozoic (Statherian) continental crust. The results herein indicate that the Morrinhos granite was generated in a continental magmatic arc in a late- to post-orogenic stage of the San Ignacio Orogeny, and it can be recognized as belonging to the Pensamiento Intrusive Suite. (author)

  20. Fission-track evidence of tectonic evolution in the northwestern Qaidam Basin, China

    Science.gov (United States)

    Sun, Guo-Qiang; Liu, Wei-Ming; Guo, Jia-Jia; Wang, Ye-Tong

    2018-02-01

    Fission-track dating was conducted on zircons and apatites from 11 cores of the upper Xiaganchaigou Formation and lower Shangganchaigou Formation (northwestern Qaidam Basin). The obtained apatite fission-track age is 3.1-61.9 Ma, and the zircon fission-track age is 49.2-123.5 Ma. Although the average apatite age is consistent with ages predicted from the stratigraphy, nine of the 11 apatite fission-track ages have P(χ2) 5%, exhibiting consistent characteristics and indicating that zircons retain provenance age information after burial. From the zircon and apatite ages, the fission-track length distribution, and the geological setting, the northwestern Qaidam Basin has experienced two tectonothermal events since the Late Mesozoic, at 39.1 ± 9.3 to 133.7 ± 6.6 Ma and 1.2 ± 0.6 to 32.0 ± 3.0 Ma. The earlier (39.1-133.7 Ma) tectonothermal event resulted from the initial collision of the Indian and Eurasian plates. As a consequence of the collision, the Altyn Tagh fault, which forms the northwestern boundary of the Qaidam Basin, began to develop. Subsequently, uplift of the Altyn Tagh mountains began and the northwestern depression of the Qaidam Basin started to form. The later (1.2-32.0 Ma) tectonothermal event resulted from further collision of the Indian and Eurasian plates along the Yarlung Tsangpo suture zone. Strata in the Qaidam Basin were further deformed by transpression in this period and this period played a crucial role in petroleum accumulation.

  1. Uranium mine waste water: a potential source of ground water in northwestern New Mexico

    International Nuclear Information System (INIS)

    Hiss, W.L.

    1977-01-01

    Substantial quantities of water are being pumped from the Morrison Formation of Late Jurassic age in uranium mines in the Grants mineral belt in northwestern New Mexico. The water often contains unacceptable amounts of dissolved uranium, radium, iron, and selenium and suspended solids, but with treatment it can be made suitable for municipal and industrial purposes. Water salvaged from current and projected mining operations constitutes the most readily available water in this otherwise water-deficient area

  2. The collection of the Herpetological Museum of the University of Antioquia (northwestern Colombia)

    OpenAIRE

    Ortiz-Yusty,Carlos; Daza,Juan; Paez,Vivian; Bock,Brian

    2015-01-01

    Abstract Northwestern South America harbors one of the richest herpetofauna in the world. The connection among several biogeographic provinces along with climatic and orographic complexity makes this region an important contributor to the Neotropical biodiversity. Despite of this importance, the amphibian and reptile fauna in this area remains largely unknown as few herpetological collections has been made in recent decades. Motivated by this, the Herpetological Museum at the Universidad de A...

  3. Modeling organic aerosol concentrations and properties during winter 2014 in the northwestern Mediterranean region

    OpenAIRE

    Chrit, Mounir; Sartelet, Karine; Sciare, Jean; Majdi, Marwa; Nicolas, José; Petit, Jean-Eudes; Dulac, François

    2018-01-01

    Organic aerosols are measured at a remote site (Ersa) on Corsica Cape in the northwestern Mediterranean basin during the Chemistry-Aerosol Mediterranean Experiment (CharMEx) winter campaign of 2014, when high organic concentrations from anthropogenic origin are observed. This work aims at representing the observed organic aerosol concentrations and properties (oxidation state) using the air-quality model Polyphemus with a surrogate approach for secondary organic aerosol (SOA) formation. Becau...

  4. Semi-detailed uranium geochemical survey in Northwestern Samar (27 March 1979 - 4 July 1979)

    International Nuclear Information System (INIS)

    Santos, G. Jr.; Ogena, M.; Tauli, G.

    1980-04-01

    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 anomalies were indicated in San Isidro and Mauo. Geochemical correlations between uranium and trace elements (Pb, Ag, Ni, Cu, Co, Zn and Mn) were generally poor. (ELC)

  5. The actual annual occurrence of the green lacewings of northwestern Europe (Neuroptera: Chrysopidae)

    OpenAIRE

    Canard, M.; Thierry, D.; Whittington, Andrew E.; Bozsik, A.

    2010-01-01

    Quantitative surveys of chrysopids from northwestern Europe were analysed. A total of thirty-five species are known within the zone although only twenty-six were recorded. Only the common green lacewings (i.e. the sibling species of the Chrysoperla carnea complex, here not differentiated) were elsewhere abundant comprising more than 3/4 of the specimens in all countries and reaching 97 % in Belgium. For the scarcer species, comments are given on their enhanced geographic range. The French fau...

  6. Variability of solar radiation and CDOM in surface coastal waters of the northwestern Mediterranean sea

    OpenAIRE

    Sempéré, Richard; Para, J.; Tedetti, Marc; Charriere, B.; Mallet, M.

    2015-01-01

    Atmospheric and in-water solar radiation, including UVR-B, UVR-A and PAR, as well as chromophoric dissolved organic matter absorption [a(CDOM)()] in surface waters were monthly measured from November 2007 to December 2008 at a coastal station in the Northwestern Mediterranean Sea (Bay of Marseilles, France). Our results showed that the UVR-B/UVR-A ratio followed the same trend in the atmosphere and at 2m depth in the water (P

  7. Mapping of incidence and management of invasive species Fallopia japonica at selected locations of northwestern Slovakia

    International Nuclear Information System (INIS)

    Paukova, Z.; Krskova, L.

    2011-01-01

    Mapping of one of the most dangerous invasive species Fallopia japonica was conducted at selected locations of northwestern Slovakia: in the cadastral territory of Zazriva, in the village Parnica towards Kralovany, in the village Kralovany and the city of Dolny Kubin - Zaskalie, stretch Timravina in the Lower Orava in late summer and early autumn 2009. We recorded by field survey 24 invading Japanese knotweed in the area of 12.238 m 2 . (authors)

  8. Ethnobotanical study of medicinal plants used by people in Zegie Peninsula, Northwestern Ethiopia

    OpenAIRE

    Giday Mirutse; Teklehaymanot Tilahun

    2007-01-01

    Abstract An ethnobotanical study was conducted from October 2005 to June 2006 to investigate the uses of medicinal plants by people in Zegie Peninsula, northwestern Ethiopia. Information was gathered from 200 people: 70 female and 130 males, using semistructured questionnaire. Of which, six were male local healers. The informants, except the healers, were selected randomly and no appointment was made prior to the visits. Informant consensus factor (ICF) for category of aliments and the fideli...

  9. Aquifers in the Sokoto basin, northwestern Nigeria, with a description of the general hydrogeology of the region

    Science.gov (United States)

    Anderson, H.R.; Ogilbee, William

    1973-01-01

    The Sokoto Basin of northwestern Nigeria lies in the sub-Saharan Sudan belt of west Africa in a zone of savannah-type vegetation. Rainfall, averaging about 30 inches annually in much of the basin, occurs chiefly in a wet season which lasts from May to October. A prolonged dry season extending from October to April is dominated by dusty harmattan winds from the northeast. April and May are the hottest months, when temperatures occasionally reach 105?F. Flow in streams of the Sokoto Basin is mostly overland runoff. Only in a few reaches, fed by ground-water discharge from the sedimentary rocks, are streams perennial. In the River Zamfara basin, ground-water discharge contributes almost 1 inch of the average 3.33 inches of total annual runoff. In the vicinity of Sokoto, the River Rima flows throughout the year sustained by spring discharge from perched ground water in limestone of the Kalambaina Formation. On the crystalline terrane where most of the streams rise, total annual runoff may exceed 5 inches, very little of which is ground-water discharge. The sedimentary rocks of the basin range in age from Cretaceous to Tertiary and are composed mostly of interbedded sand, clay, and some limestone; the beds dip gently toward the northwest. Alluvium of Quaternary age underlies the lowlands of the River Sokoto (now Sokoto) and its principal tributaries. These rocks contain three important artesian aquifers, in addition to regional unconfined ground-water bodies in all the principal outcron areas, and a perched water body in the outcrop of the Kalambaina Formation. Artesian aquifers occur at depth in the Gundumi Formation, the Rima Group, and the Gwandu Formation and are separated from one another by clay beds in the lower part of the Rima Group and the Dange Formation. In outcrop, clay in the Dange Formation also supports the perched water of the Kalambaina Formation. The Gundumi Formation, resting on the basement complex, is composed of varicolored clay, sand, and gravel

  10. Shoshonitic- and adakitic magmatism of the Early Paleozoic age in the Western Kunlun orogenic belt, NW China: Implications for the early evolution of the northwestern Tibetan plateau

    Science.gov (United States)

    Wang, Jian; Hattori, Keiko; Liu, Jianguo; Song, Yue; Gao, Yongbao; Zhang, Han

    2017-08-01

    The Western Kunlun orogenic belt in the northwestern margin of the Tibetan plateau contains two magmatic belts; early Paleozoic belt in the northern part of Western Kunlun Terrane (WKT), and early Mesozoic belt in the southern part of WKT. Both formed from northward subduction of the Paleo-Tethys. The early Paleozoic belt contains large Datong and Qiukesu igneous complexes and many smaller plutons. The Datong complex is mainly composed of dark-colored porphyritic syenite and monzonite with minor light-colored dykes of granite and monzonite. The dark-colored rocks are characterized by moderate SiO2 (58.2-69.3 wt.%), and high Al2O3 (15.3-17.1 wt.%), total alkali (Na2O + K2O = 8.07-10.2 wt.%) and ratios of K2O/Na2O (0.77-1.83). They plot in "shoshonite" field, and show high abundances of LILE including LREE ((La/Yb)n = 15.4-26.2; mean 20.2) with pronounced negative anomalies of Nb-Ta-P-Ti in normalized trace elemental patterns and weak negative anomalies of Eu (δEu = 2Eun/(Smn + Gdn) = 0.68-0.80). The light-colored rocks contain slightly higher concentrations of SiO2 (60.3-72.0 wt.%), similar Al2O3 (14.7-17.6 wt.%), and slightly lower total alkalis (6.57-9.14 wt.%) than dark-colored rocks. They show adakitic geochemical signatures with low Y (5.80-17.2 ppm) and Yb (0.63-1.59 ppm), and high Sr/Y (> 40). U-Pb zircon dating indicates that shoshonitic rocks and adakitic dykes formed at 444 Ma to 443 Ma, and a separate small adakitic plug at 462 Ma. The mean εHf(t) values of zircon range from - 1.6 to - 0.94 (n = 14) with TDM2 of 1.5 Ga for shoshonitic rocks and εHf(t) values from - 1.8 to + 0.72 (n = 12) with TDM2 of 1.4 to 1.5 Ga for adakitic rocks. Shoshonitic rocks show initial 87Sr/86Sr and εNd(t) of 0.7092-0.7100 and - 3.9 to - 3.2, respectively, and adakitic rocks yield initial 87Sr/86Sr and εNd(t) of 0.7099-0.7134 and - 3.6 to - 3.1, respectively. Similar Sr, Nd, and Hf isotope compositions for the shoshonitic and adakitic rocks suggest similar ancient rocks

  11. Geochronology of plutonic rocks and their tectonic terranes in Glacier Bay National Park and Preserve, southeast Alaska: Chapter E in Studies by the U.S. Geological Survey in Alaska, 2008-2009

    Science.gov (United States)

    Brew, David A.; Tellier, Kathleen E.; Lanphere, Marvin A.; Nielsen, Diane C.; Smith, James G.; Sonnevil, Ronald A.

    2014-01-01

    We have identified six major belts and two nonbelt occurrences of plutonic rocks in Glacier Bay National Park and Preserve and characterized them on the basis of geologic mapping, igneous petrology, geochemistry, and isotopic dating. The six plutonic belts and two other occurrences are, from oldest to youngest: (1) Jurassic (201.6–145.5 Ma) diorite and gabbro of the Lituya belt; (2) Late Jurassic (161.0–145.5 Ma) leucotonalite in Johns Hopkins Inlet; (3) Early Cretaceous (145.5–99.6 Ma) granodiorite and tonalite of the Muir-Chichagof belt; (4) Paleocene tonalite in Johns Hopkins Inlet (65.5–55.8 Ma); (5) Eocene granodiorite of the Sanak-Baranof belt; (6) Eocene and Oligocene (55.8–23.0 Ma) granodiorite, quartz diorite, and granite of the Muir-Fairweather felsic-intermediate belt; (7) Eocene and Oligocene (55.8–23.0 Ma) layered gabbros of the Crillon-La Perouse mafic belt; and (8) Oligocene (33.9–23.0 Ma) quartz monzonite and quartz syenite of the Tkope belt. The rocks are further classified into 17 different combination age-compositional units; some younger belts are superimposed on older ones. Almost all these plutonic rocks are related to Cretaceous and Tertiary subduction events. The six major plutonic belts intrude the three southeast Alaska geographic subregions in Glacier Bay National Park and Preserve, from west to east: (1) the Coastal Islands, (2) the Tarr Inlet Suture Zone (which contains the Border Ranges Fault Zone), and (3) the Central Alexander Archipelago. Each subregion includes rocks assigned to one or more tectonic terranes. The various plutonic belts intrude different terranes in different subregions. In general, the Early Cretaceous plutons intrude rocks of the Alexander and Wrangellia terranes in the Central Alexander Archipelago subregion, and the Paleogene plutons intrude rocks of the Chugach, Alexander, and Wrangellia terranes in the Coastal Islands, Tarr Inlet Suture Zone, and Central Alexander Archipelago subregions.

  12. Brittle deformation in Southern Granulite Terrane (SGT): A study of pseudotachylyte bearing fractures along Gangavalli Shear Zone (GSZ), Tamil Nadu, India.

    Science.gov (United States)

    mohan Behera, Bhuban; Thirukumaran, Venugopal; Biswal, Tapas kumar

    2016-04-01

    High grade metamorphism and intense deformation have given a well recognition to the Southern Granulite Terrane (SGT) in India. TTG-Charnockite and basic granulites constitute the dominant lithoassociation of the area. Dunite-peridotite-anorthosite-shonkinite and syenites are the intrusives. TTG-charnockite-basic granulite have undergone F1 (isoclinal recumbent), F2 (NE-SW) and F3 (NW-SE) folds producing several interference pattern. E-W trending Neoarchean and Palaeoproterozoic Salem-Attur Shear Zone exhibits a low angle ductile thrust as well as some foot print of late stage brittle deformation near Gangavalli area of Tamil Nadu. The thrust causes exhumation of basic granulites to upper crust. Thrusting along the decollement has retrograded the granulite into amphibolite rock. Subsequently, deformation pattern of Gangavalli area has distinctly marked by numerous vertical to sub-vertical fractures mostly dominating along 0-15 and 270-300 degree within charnockite hills that creates a maximum stress (σ1) along NNW and minimum stress (σ3) along ENE. However, emplacement of pseudotachylyte vein along N-S dominating fracture indicates a post deformational seismic event. Extensive fractures produce anastomose vein with varying thickness from few millimeters to 10 centimeters on the outcrop. ICP-AES study results an isochemical composition of pseudotachylyte vein that derived from the host charnockitic rock where it occurs. But still some noticeable variation in FeO-MgO and Na2O-CaO are obtained from different parts within the single vein showing heterogeneity melt. Electron probe micro analysis of thin sections reveals the existence of melt immiscibility during its solidification. Under dry melting condition, albitic rich melts are considered to be the most favorable composition for microlites (e.g. sheaf and acicular micro crystal) re-crystallization. Especially, acicular microlites preserved tachylite texture that suggest its formation before the final coagulation

  13. New Geochronology and Radiometric Age Dates Improve the Definition and Continuity of Accreted Tectonic Terranes of Northern Venezuela and the Lesser Antilles

    Science.gov (United States)

    Baquero, M.; Mann, P.; Audemard, F. A.

    2017-12-01

    We use new and compiled geochronology and radiometric dates from the area of Venezuela to Tobago to define the following crustal provinces: 1) Guyana shield forms a sub-circular area of Pan-African rocks against which all younger terranes have collided and partially assumed its rounded shape: ages for the Guyana Shield range from >3.4 Ga to 1.8 Ga; 2) accreted Paleozoic rocks form a sub-circular, largely buried province that surround the Guiana Shield to the north and west; the El Pilar strike-slip fault forms the abrupt, northern limit of the Precambrian-Paleozoic craton in Venezuela characterized by crustal thicknesses of 40-50 km; 3) the Early to Late Cretaceous Great Arc of the Caribbean forms a continuous basement high that can be traced from northern Colombia, through the ABC Islands to La Blanquilla Island, and north along the Aves Ridge to the Greater Antilles; ages of the GAC generally are in the range of Late Cretaceous to early Eocene and have geochemistry consistent with intra-oceanic island arcs or oceanic plateau rocks with the exception of La Orchila Island with a Paleozoic intrusive age; the GAC collided from west to east with the passive margin of South America from Paleocene in western Venezuela to Plio-Pleistocene in the Trinidad area and marks the west to east passage of the Caribbean plate past the South American plate; 4) a post-GAC rifting event affected the GAC-South America suture from late Eocene to middle Miocene time in the Falcón Basin of western Venezuela with ages on intrusive and volcanic from 34 to 15.4 Ma; these ages are coeval with intrusive ages from the southernmost Lesser Antilles on Los Frailes and Los Testigos Islands and range from 35.7±2.6 to 36.4±0.5 Ma; the age of the intervening basin, the Bonaire basin, is poorly known but may be coeval with the Oligocene-Miocene extension that extended the suture zone in western Venezuela and extended the Lesser Antilles arc in early Middle Miocene time to form the Lesser Antilles

  14. Using remote sensing techniques and field-based structural analysis to explore new gold and associated mineral sites around Al-Hajar mine, Asir terrane, Arabian Shield

    Science.gov (United States)

    Sonbul, Abdullah R.; El-Shafei, Mohamed K.; Bishta, Adel Z.

    2016-05-01

    Modern earth resource satellites provide huge amounts of digital imagery at different resolutions. These satellite imageries are considered one of the most significant sources of data for mineral exploration. Image processing techniques were applied to the exposed rocks around the Al-Aqiq area of the Asir terrane in the southern part of the Arabian Shield. The area under study has two sub-parallel N-S trending metamorphic belts of green-schist facies. The first belt is located southeast of Al-Aqiq, where the Al-Hajar Gold Mine is situated. It is essentially composed of metavolcanics and metasedimentary rocks, and it is intruded by different plutonic rocks of primarily diorite, syenite and porphyritic granite. The second belt is located northwest of Al-Aqiq, and it is composed of metavolcanics and metasedimentary rocks and is intruded by granite bodies. The current study aimed to distinguish the lithological units, detect and map the alteration zones, and extract the major fault lineaments around the Al-Hajar gold prospect. Digital satellite imageries, including Landsat 7 ETM + multispectral and panchromatic and SPOT-5 were used in addition to field verification. Areas with similar spectral signatures to the prospect were identified in the nearby metamorphic belt; it was considered as a target area and was inspected in the field. The relationships between the alteration zones, the mineral deposits and the structural elements were used to locate the ore-bearing zones in the subsurface. The metasedimentary units of the target area showed a dextral-ductile shearing top-to-the-north and the presence of dominant mineralized quartz vein-system. The area to the north of the Al-Hajar prospect showed also sub-parallel shear zones along which different types of alterations were detected. Field-based criteria such as hydrothermal breccia, jasper, iron gossans and porphyritic granite strongly indicate the presence of porphyry-type ore deposits in Al-Hajar metamorphic belt that

  15. The Vegetation of North-Western Mongolia: Floristic Checklist and Conservation Status of Mongolian Grassland Flora

    Directory of Open Access Journals (Sweden)

    Katharina Lapin

    2017-05-01

    Full Text Available Mongolia´s grassland (steppe is reported to be vulnerable to climate change, degradation, and densifi cation. The traditional Mongolian pastoral herding system is currently transforming due to changes in market relations and economic developments, and this transformation has an impact on species composition and biodiversity. For this study, we observed the current situation of the fl ora in the north-western Mongolian territories to provide data on plant species occurrence in this remote area. A vegetation assessment was conducted for 15 locations in June and July 2016. Indicator plant species were determined to assess the level of grazing and degradation, as well as the respective steppe sub-type. The conservation status of all recorded plant species was assessed in accordance with the IUCN Red List. In total, 106 vascular plant species belonging to 73 genera and 26 families were recorded. Four endemic plant species were observed. All locations were classifi ed into three steppe sub-types: Desert-steppe, dry-steppe and mountain-steppe. A large number of degradation indicator plant species were observed in almost all locations. No endangered species in the Mongolian IUCN Red List were observed. The observation indicates that the vegetation in the north-western area of Mongolia is partly showing tendencies towards overgrazing and degradation. The conservation status of the most recorded species is currently unknown, and more studies on Mongolian vegetation will need to be conducted to assess these species’ status. We emphasize the urgent need for further studies on the vegetation and plant species composition, and indicators in north-western Mongolia, especially in context of the ongoing rapid economic, social, and ecological changes in the region

  16. Fluvial response to the last Holocene rapid climate change in the Northwestern Mediterranean coastlands

    Science.gov (United States)

    Degeai, Jean-Philippe; Devillers, Benoît; Blanchemanche, Philippe; Dezileau, Laurent; Oueslati, Hamza; Tillier, Margaux; Bohbot, Hervé

    2017-05-01

    The variability of fluvial activity in the Northwestern Mediterranean coastal lowlands and its relationship with modes of climate change were analysed from the late 9th to the 18th centuries CE. Geochemical analyses were undertaken from a lagoonal sequence and surrounding sediments in order to track the fluvial inputs into the lagoon. An index based on the K/S and Rb/S ratios was used to evidence the main periods of fluvial activity. This index reveals that the Medieval Climate Anomaly (MCA) was a drier period characterized by a lower fluvial activity, while the Little Ice Age (LIA) was a wetter period with an increase of the river dynamics. Three periods of higher than average fluvial activity were evidenced at the end of the first millennium CE (ca. 900-950 cal yr CE), in the first half of the second millennium CE (ca. 1150-1550 cal yr CE), and during the 1600s-1700s CE (ca. 1650-1800 cal yr CE). The comparison of these fluvial periods with other records of riverine or lacustrine floods in Spain, Italy, and South of France seems to indicate a general increase in fluvial and flood patterns in the Northwestern Mediterranean in response to the climate change from the MCA to the LIA, although some episodes of flooding are not found in all records. Besides, the phases of higher than average fluvial dynamics are in good agreement with the North Atlantic cold events evidenced from records of ice-rafted debris. The evolution of fluvial activity in the Northwestern Mediterranean coastlands during the last millennium could have been driven by atmospheric and oceanic circulation patterns.

  17. Origin of the mafic microgranular enclaves (MMEs) and their host granitoids from the Tagong pluton in Songpan-Ganze terrane: An igneous response to the closure of the Paleo-Tethys ocean

    Science.gov (United States)

    Chen, Qiong; Sun, Min; Zhao, Guochun; Yang, Fengli; Long, Xiaoping; Li, Jianhua; Wang, Jun; Yu, Yang

    2017-10-01

    The Songpan-Ganze terrane is mainly composed of a Triassic sedimentary sequence and late Triassic-Jurassic igneous rocks. A large number of plutons were emplaced as a result of tectono-magmatic activity related to the late stages of Paleo-Tethys ocean closure and ensuing collision. Granitoids and their hosted mafic enclaves can provide important constraints on the crust-mantle interaction and continental crustal growth. Mesozoic magmatism of Songpan-Ganze remains enigmatic with regard to their magma generation and geodynamic evolution. The Tagong pluton (209 Ma), in the eastern part of the Songpan-Ganze terrane, consists mainly of monzogranite and granodiorite with abundant coeval mafic microgranular enclaves (MMEs) (ca. 208-209 Ma). The pluton comprises I-type granitoid that possesses intermediate to acidic compositions (SiO2 = 61.6-65.8 wt.%), high potassium (K2O = 3.2-4.1 wt.%), and high Mg# (51-54). They are also characterized by arc-type enrichment of LREEs and LILEs, depletion of HFSEs (e.g. Nb, Ta, Ti) and moderate Eu depletions (Eu/Eu* = 0.46-0.63). Their evolved zircon Hf and whole-rock Nd isotopic compositions indicate that their precursor magmas were likely generated by melting of old lower continental crust. Comparatively, the MMEs have lower SiO2 (53.4-58.2 wt.%), higher Mg# (54-67) and show covariation of major and trace elements, coupled with field and petrographic observations, such as the disequilibrium textures of plagioclase and amphibole, indicating that the MMEs and host granitoids were originated from different magma sources but underwent mafic-felsic magma mixing process. Geochemical and isotopic data further suggest that the precursor magma of the MMEs was formed in the continental arc setting, mainly derived from an ancient metasomatized lithospheric mantle wedge. The Triassic granitoids from the Songpan-Ganze terrane show remarkable temporal-spatial-petrogenetic affinities to the counterparts of subduction zones in the Yidun and Kunlun arc

  18. Scepticism towards insecticide treated mosquito nets for malaria control in a rural community in northwestern Tanzania

    DEFF Research Database (Denmark)

    Nnko, Soori; Whyte, Susan Reynolds; Geissler, Wenzel

    2012-01-01

    in Mwanza region, North-Western Tanzania. The study explores reasons for scepticism and low uptake of insecticide treated mosquito nets (ITNs) that were promoted through social marketing strategy for malaria control prior to the introduction of long lasting nets (LLN). The paper breaks from traditional...... attendances. In terms of mortality, malaria is known to be responsible for more than one third of deaths among children of age below 5 years and also contributes for up to one fifth of deaths among pregnant women. This paper is based on a study conducted in a rural community along the shores of Lake Victoria...

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

    DEFF Research Database (Denmark)

    van der Fels-Klerx, H J; Olesen, Jørgen E; Madsen, M S

    2012-01-01

    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....

  20. The last Scandinavian ice sheet in northwestern Russia: ice flow patterns and decay dynamics

    DEFF Research Database (Denmark)

    Demidov, L.; Houmark-Nielsen, Michael; Kjær, Kurt Henrik

    2006-01-01

    in Russia than previously outlined and the time of termination at 18-16 cal. kyr BP was almost 10 kyr delayed compared to the southwestern part of the ice sheet. We argue that the lithology of the ice sheets' substrate, and especially the location of former proglacial lake basins, influenced the dynamics......Advance of the Late Weichselian (Valdaian) Scandinavian Ice Sheet (SIS) in northwestern Russia took place after a period of periglacial conditions. Till of the last SIS, Bobrovo till, overlies glacial deposits from the previous Barents and Kara Sea ice sheets and marine deposits of the Last...

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

    International Nuclear Information System (INIS)

    Aravena, R.; Dinel, H.

    1993-01-01

    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

  2. A nearly modern amphibious bird from the Early Cretaceous of northwestern China.

    Science.gov (United States)

    You, Hai-Lu; Lamanna, Matthew C; Harris, Jerald D; Chiappe, Luis M; O'connor, Jingmai; Ji, Shu-An; Lü, Jun-Chang; Yuan, Chong-Xi; Li, Da-Qing; Zhang, Xing; Lacovara, Kenneth J; Dodson, Peter; Ji, Qiang

    2006-06-16

    Three-dimensional specimens of the volant fossil bird Gansus yumenensis from the Early Cretaceous Xiagou Formation of northwestern China demonstrate that this taxon possesses advanced anatomical features previously known only in Late Cretaceous and Cenozoic ornithuran birds. Phylogenetic analysis recovers Gansus within the Ornithurae, making it the oldest known member of the clade. The Xiagou Formation preserves the oldest known ornithuromorph-dominated avian assemblage. The anatomy of Gansus, like that of other non-neornithean (nonmodern) ornithuran birds, indicates specialization for an amphibious life-style, supporting the hypothesis that modern birds originated in aquatic or littoral niches.

  3. An Interactive Computer-Based Circulation System for Northwestern University: The Library Puts It to Work

    Directory of Open Access Journals (Sweden)

    Velma Veneziano

    1972-06-01

    Full Text Available Northwestern University Library's on-line circulation system has resulted in dramatic changes in practices and procedures in the Circulation Services Section. After a hectic period of implementation, the staff soon began to adjust to the system. Over the past year and a half, they have devised ways to use the system to maximum advantage, so that manual and machine systems now mesh in close harmony. Freed from time-consuming clerical chores, the staff have been challenged to use their released time to best advantage, with the result that the "service" in "Circulation Services" is much closer to being a reality.

  4. Map showing reconnaissance geochemistry in the gold-pyrophyllite belt of northwestern Moore County, North Carolina

    Science.gov (United States)

    Lesure, Frank G.

    1981-01-01

    Traces of gold and molybdenum are widely disseminated in an area approximately 35 km long and 10 km wide in northwestern Moore County, N.C.  At least 2540 oz. of gold were recovered from 16 or more mines and prospects between 1880 and 1910.  One hundred and ninety rock samples out of 244 collected from old gold mines, pyrophyllite deposits and along roads contain gold quantities ranging from 0.02 to 2.4 parts per million.  In addition, 43 samples out of the 244 taken contain molybdenum in amounts ranging from 4 to 500 parts per million.

  5. Detection of Russian olive witches’-broom disease and its insect vector in Northwestern Iran

    Directory of Open Access Journals (Sweden)

    Hajizadeh Abasalt

    2017-09-01

    Full Text Available Recently, Russian olive trees showing witches’-broom and little leaf symptoms have been widely observed in northwestern and central Iran. Polymerase chain reaction (PCR and nested PCR assays using phytoplasma universal primer pairs confirmed phytoplasma symptomatic infection of trees. Sequence analyses showed that ‘Candidatus Phytoplasma asteris’ was the causal agent of the disease in these regions. However, RFLP results using restriction enzymes HpaII, EcoRI, HinfI and AluI indicated that the collected isolates in these regions are genetically different. In addition, leafhopper Macropsis infuscata was recognized as a possible insect vector of the disease for the first time.

  6. Food composition of some low altitude Lissotriton montandoni (Amphibia, Caudata populations from North-Western Romania

    Directory of Open Access Journals (Sweden)

    Covaciu-Marcov S.D.

    2010-01-01

    Full Text Available The diet of some populations of Lissotriton montandoni from north-western Romania is composed of prey belonging to 20 categories. The food components of the Carpathian newts are similar to those of other species of newts. Most of the prey are aquatic animals, but terrestrial prey also has a high percentage abundance. The consumed prey categories are common in the newts' habitats as well, but in natural ponds the prey item with the highest abundance in the diet is not the most frequent one in the habitat. Thus, although the Carpathian newts are basically opportunistic predators, they still display a certain trophic selectivity.

  7. The agribusiness industry in northwestern Mexico and the health of female farmworkers: a proposal for study

    Directory of Open Access Journals (Sweden)

    Patricia Aranda

    2016-03-01

    Full Text Available This article seeks to outline the structure of the export-oriented agribusiness industry in northwestern Mexico, so as to analyze the conditions of vulnerability of female farmworkers in terms of their access to health services and the medical attention they receive. Using a qualitative approach, focus groups and interviews were carried out with farmworkers and subject experts pertaining to academia and civil society. Their narratives were then analyzed using Pierre Bourdieu’s concept of field. The primary results demonstrate a lack of access to health services and social security, and describe the main actors and their positions with respect to the vulnerability of this population.

  8. An annotated checklist of the Chilopoda and Diplopoda (Myriapoda) of the Abrau Peninsula, northwestern Caucasus, Russia

    Science.gov (United States)

    Semenyuk, Irina I.; Tuf, Ivan H.

    2016-01-01

    Abstract Background The Abrau Peninsula is located in northwestern Caucasus between the cities of Novorossiysk and Anapa, Krasnodar Province, Russia. This paper contains an annotated checklist of the Chilopoda and Diplopoda inhabiting the Abrau Peninsula. New information The fauna of the Abrau Peninsula comprises 17 centipede (4 orders) and 16 millipede (6 orders) species. Henia taurica, hitherto known only from the Crimea, has now been reported from several localities in the studied region. The study also reveals two possibly new millipede species. Statistical analyses showed that habitat preferences of myriapod species within the Abrau Peninsula are caused by species geographic distribution pattern and microbiotope preferences. PMID:27346949

  9. First record of a digenean from invasive lionfish, Pterois cf. volitans, (Scorpaeniformes: Scorpaenidae) in the northwestern Atlantic Ocean.

    Science.gov (United States)

    Bullard, S A; Barse, A M; Curran, S S; Morris, J A

    2011-10-01

    Adults of Lecithochirium floridense (Digenea: Hemiuridae) parasitized the stomach in each of 22 necropsied lionfish, Pterois cf. volitans (Scorpaeniformes: Scorpaenidae) (prevalence  =  100%, mean intensity  =  11), captured in the northwestern Atlantic Ocean off Beaufort, North Carolina (34°14.83'N, 76°35.25'W). This is the first report of a digenean from the invasive lionfish and that of L. floridense from a species of Pterois. The leech specimen previously identified as Myzobdella lugubris from P. volitans in the northwestern Atlantic Ocean is re-identified as Trachelobdella lubrica based on a study of the original voucher specimen.

  10. Mobility and Fate of Pollutants in the Aquifer System of the Northwestern Suez Gulf, Egypt.

    Science.gov (United States)

    Snousy, Moustafa Gamal; Zawrah, M F; Abdel-Moghny, Th; Ebiad, M A; Rashad, A M; Khalil, Mahmoud M; Abu El Ella, E M; El-Sayed, E; Tantawy, M A

    The northwestern part of Suez Gulf region is a strategic area in Egypt. It includes important sources of national income. To achieve the development goals, the government has established huge projects in this area (e.g. establishment and expanding of a large commercial port at Ain Sokhna, many industrial zones as well as tourism projects). The utilization of the Suez Gulf resources and their continuing development mainly depend on the creation of actual pollution control programs. The environmental quality control and pollution reduction activities are important ingredients of any economic development program. These different activities in this area depend mainly on the groundwater that is pumped intensively from different water bearing formations or aquifers. The main objective of the present work is compiling the previous studies from the 1980s up to 2015. These studies are concerned with estimating the concentrations of different pollutants in various ecosystems in the northwestern Suez Gulf region. Also, to provide an explanation for the movement of different pollutants such as organic and heavy metals from contaminated land to ground and surface (Gulf) waters. This issue has not been extensively surveyed before, and this review, gives specific directions for future monitoring and remediation strategies in this region.

  11. Technological innovations in the horticultural sector in northwestern Mexico: adoption speed and diffusion networks analysis

    Directory of Open Access Journals (Sweden)

    Belem Dolores Avendaño-Ruiz

    2017-09-01

    Full Text Available The article focuses on the identification of innovation adoption and diffusion processes in the export horticultural sector in northwestern Mexico, and the differences identified taking into account the type of producer depending on the production size. The results of the adoption speed index suggests that large producers are distinguished as being early adopters and leaders in innovation adoption in this activity; but as long as there is a technological gap between small and large producers, that is increased even more by economical limita-tions, these will be identified as late adopters for this activity, supported by public programs for its adoption. The study was conducted in four entities of northwestern Mexico, Baja California, Baja California Sur, Sonora and Sinaloa, that in average contribute with 17 % of the national horticultural production. The international market is a strong promotor in innovation adoption, particularly in those related to food safety standards that are adopted by 84 % of the producers. The network analysis highlights the role of union organizations as technological innovation diffusors, e.g. the Confederation of Agricultural Associations of the Sinaloa State, and the Local Agricultural Association of horticulture, Fruits and Legumes of Hermosillo in Sonora.

  12. Impacts of surface water diversions for marijuana cultivation on aquatic habitat in four northwestern California watersheds.

    Directory of Open Access Journals (Sweden)

    Scott Bauer

    Full Text Available Marijuana (Cannabis sativa L. cultivation has proliferated in northwestern California since at least the mid-1990s. The environmental impacts associated with marijuana cultivation appear substantial, yet have been difficult to quantify, in part because cultivation is clandestine and often occurs on private property. To evaluate the impacts of water diversions at a watershed scale, we interpreted high-resolution aerial imagery to estimate the number of marijuana plants being cultivated in four watersheds in northwestern California, USA. Low-altitude aircraft flights and search warrants executed with law enforcement at cultivation sites in the region helped to validate assumptions used in aerial imagery interpretation. We estimated the water demand of marijuana irrigation and the potential effects water diversions could have on stream flow in the study watersheds. Our results indicate that water demand for marijuana cultivation has the potential to divert substantial portions of streamflow in the study watersheds, with an estimated flow reduction of up to 23% of the annual seven-day low flow in the least impacted of the study watersheds. Estimates from the other study watersheds indicate that water demand for marijuana cultivation exceeds streamflow during the low-flow period. In the most impacted study watersheds, diminished streamflow is likely to have lethal or sub-lethal effects on state- and federally-listed salmon and steelhead trout and to cause further decline of sensitive amphibian species.

  13. Soil, environmental, and watershed measurements in support of carbon cycling studies in northwestern Mississippi

    Science.gov (United States)

    Huntington, T.G.; Harden, J.W.; Dabney, S.M.; Marion, D.A.; Alonso, C.; Sharpe, J.M.; Fries, T.L.

    1998-01-01

    Measurements including soil respiration, soil moisture, soil temperature, and carbon export in suspended sediments from small watersheds were recorded at several field sites in northwestern Mississippi in support of hillslope process studies associated with the U.S. Geological Survey's Mississippi Basin Carbon Project (MBCP). These measurements were made to provide information about carbon cycling in agricultural and forest ecosystems to understand the potential role of erosion and deposition in the sequestration of soil organic carbon in upland soils. The question of whether soil erosion and burial constitutes an important net sink of atmospheric carbon dioxide is one hypothesis that the MBCP is evaluating to better understand carbon cycling and climate change. This report contains discussion of methods used and presents data for the period December 1996 through March 1998. Included in the report are ancillary data provided by the U.S. Department of Agriculture (USDA) ARS National Sedimentation Laboratory and U.S. Forest Service (USFS) Center for Bottomland Hardwoods Research on rainfall, runoff, sediment yield, forest biomass and grain yield. Together with the data collected by the USGS these data permit the construction of carbon budgets and the calibration of models of soil organic matter dynamics and sediment transport and deposition. The U.S. Geological Survey (USGS) has established cooperative agreements with the USDA and USFS to facilitate collaborative research at research sites in northwestern Mississippi.

  14. Upper Paleozoic Marine Shale Characteristics and Exploration Prospects in the Northwestern Guizhong Depression, South China

    Science.gov (United States)

    Zhu, Zhenhong; Yao, Genshun; Lou, Zhanghua; Jin, Aimin; Zhu, Rong; Jin, Chong; Chen, Chao

    2018-05-01

    Multiple sets of organic-rich shales developed in the Upper Paleozoic of the northwestern Guizhong Depression in South China. However, the exploration of these shales is presently at a relatively immature stage. The Upper Paleozoic shales in the northwestern Guizhong Depression, including the Middle Devonian Luofu shale, the Nabiao shale, and the Lower Carboniferous Yanguan shale, were investigated in this study. Mineral composition analysis, organic matter analysis (including total organic carbon (TOC) content, maceral of kerogen and the vitrinite reflection (Ro)), pore characteristic analysis (including porosity and permeability, pore type identification by SEM, and pore size distribution by nitrogen sorption), methane isothermal sorption test were conducted, and the distribution and thickness of the shales were determined, Then the characteristics of the two target shales were illustrated and compared. The results show that the Upper Paleozoic shales have favorable organic matter conditions (mainly moderate to high TOC content, type I and II1 kerogen and high to over maturity), good fracability potential (brittleness index (BI) > 40%), multiple pore types, stable distribution and effective thickness, and good methane sorption capacity. Therefore, the Upper Paleozoic shales in the northern Guizhong Depression have good shale gas potential and exploration prospects. Moreover, the average TOC content, average BI, thickness of the organic-rich shale (TOC > 2.0 wt%) and the shale gas resources of the Middle Devonian shales are better than those of the Lower Carboniferous shale. The Middle Devonian shales have better shale gas potential and exploration prospects than the Lower Carboniferous shales.

  15. Seasonal variation and chemical characterization of PM2.5 in northwestern Philippines

    Science.gov (United States)

    Bagtasa, Gerry; Cayetano, Mylene G.; Yuan, Chung-Shin

    2018-04-01

    The seasonal and chemical characteristics of fine particulate matter (PM2.5) were investigated in Burgos, Ilocos Norte, located at the northwestern edge of the Philippines. Each 24 h sample of fine aerosol was collected for four seasons. Fine particulate in the region shows strong seasonal variation in both concentration and composition. Highest mass concentration was seen during the boreal spring season with a mean mass concentration of 21.6 ± 6.6 µg m-3, and lowest was in fall with a mean concentration of 8.4 ± 2.3 µg m-3. Three-day wind back trajectory analysis of air mass reveals the influence of the northwestern Pacific monsoon regimes on PM2.5 concentration. During southwest monsoon, sea salt was the dominant component of fine aerosols carried by moist air from the South China Sea. During northeast monsoon, on the other hand, both wind and receptor model analysis showed that higher particulate concentration was due to the long-range transport (LRT) of anthropogenic emissions from northern East Asia. Overall, sea salt and soil comprise 33 % of total PM2.5 concentration, while local biomass burning makes up 33 %. LRT of industrial emission, solid waste burning and secondary sulfate from East Asia have a mean contribution of 34 % to the total fine particulate for the whole sampling period.

  16. Biochar-based bioenergy and its environmental impact in Northwestern Ontario Canada:A review

    Institute of Scientific and Technical Information of China (English)

    Krish Homagain; Chander Shahi; Nancy Luckai; Mahadev Sharma

    2014-01-01

    Biochar is normally produced as a by-product of bioenergy. However, if biochar is produced as a co-product with bioenergy from sustainably managed forests and used for soil amendment, it could pro-vide a carbon neutral or even carbon negative solution for current envi-ronmental degradation problems. In this paper, we present a comprehen-sive review of biochar production as a co-product of bioenergy and its implications. We focus on biochar production with reference to biomass availability and sustainability and on biochar utilization for its soil amendment and greenhouse gas emissions reduction properties. Past studies confirm that northwestern Ontario has a sustainable and sufficient supply of biomass feedstock that can be used to produce bioenergy, with biochar as a co-product that can replace fossil fuel consumption, increase soil productivity and sequester carbon in the long run. For the next step, we recommend that comprehensive life cycle assessment of bio-char-based bioenergy production, from raw material collection to biochar application, with an extensive economic assessment is necessary for making this technology commercially viable in northwestern Ontario.

  17. Transit traverse in Missouri, 1900-1937. Part 4, Northwestern Missouri, 1911-37

    Science.gov (United States)

    Staack, John G.

    1940-01-01

    This bulletin, which for convenience is to be published in eight parts, contains the results of all transit traverse* done In Missouri through 1937 by the Geological Survey, United States Department of the Interior, including those heretofore published. (See page X.) Each of the parts deals with one of eight sections into which the State has been divided for this purpose and which have been designated northeastern, northwestern, southeastern, southwestern, central, east-central, south-central, and west-central Missouri. In each part descriptions of the points for which geodetic positions have been determined are listed according to the quadrangles in which the points occur. Results of transit traverse other than that done by the Geological Survey have not been included.Northwestern Missouri, as the term is used in this bulletin and as the subject of part 4 of the bulletin, is that section of the State lying north of latitude 39°30' and west of longitude 93°15'

  18. Demand for storage of natural gas in northwestern Europe: Trends 2005-30

    International Nuclear Information System (INIS)

    Hoeffler, Felix; Kuebler, Madjid

    2007-01-01

    We provide an estimation of the additional need for underground storage facilities in northwestern Europe until 2030. Storage is one important source to provide supply flexibility in order to match the seasonal demand for natural gas. However, this supply flexibility is now largely provided in northwestern Europe by indigenous production. Declining reserves will increase the dependency on imports from far-off sources, which are less flexible. Hence, flexibility must be provided by additional storage. Our estimation is based on production and consumption forecasts for natural gas and observations of the relationship between the supply and demand of gas and the supply and demand of flexibility in the period 1995-2005. We provide different scenarios to check for the robustness of our results. We estimate that by 2030, between 10.2 (with no strategic storage) and 29.0 billion cubic meters (BCM) of working gas volume (with 10 percent strategic storage for imports from non-EU countries) will be required, in addition to the existing 40 BCM. We conclude that, with well-functioning markets for flexibility, market forces could close a storage gap of 10.2 BCM in time. Strategic storage obligations would require state intervention and a well-balanced relation between a regulated part of the storage market for strategic reserves and the market for the operational use of storage

  19. Environmental variability and chum salmon production at the northwestern Pacific Ocean

    Science.gov (United States)

    Kim, Suam; Kang, Sukyung; Kim, Ju Kyoung; Bang, Minkyoung

    2017-12-01

    Chum salmon, Oncorhynchus keta, are distributed widely in the North Pacific Ocean, and about 76% of chum salmon were caught from Russian, Japanese, and Korean waters of the northwestern Pacific Ocean during the last 20 years. Although it has been speculated that the recent increase in salmon production was aided by not only the enhancement program that targeted chum salmon but also by favorable ocean conditions since the early 1990s, the ecological processes for determining the yield of salmon have not been clearly delineated. To investigate the relationship between yield and the controlling factors for ocean survival of chum salmon, a time-series of climate indices, seawater temperature, and prey availability in the northwestern Pacific including Korean waters were analyzed using some statistical tools. The results of cross-correlation function (CCF) analysis and cumulative sum (CuSum) of anomalies indicated that there were significant environmental changes in the North Pacific during the last century, and each regional stock of chum salmon responded to the Pacific Decadal Oscillation (PDO) differently: for Russian stock, the correlations between PDO index and catch were significantly negative with a time-lag of 0 and 1 years; for Japanese stock, significantly positive with a timelag of 0-2 years; and for Korean stock, positive but no significant correlation. The results of statistical analyses with Korean chum salmon also revealed that a coastal seawater temperature over 14°C and the return rate of spawning adults to the natal river produced a significant negative correlation.

  20. Spectral Wave Characteristics in the Nearshore Waters of Northwestern Bay of Bengal

    Science.gov (United States)

    Anjali Nair, M.; Sanil Kumar, V.; Amrutha, M. M.

    2018-03-01

    The spectral wave characteristics in the nearshore waters of northwestern Bay of Bengal are presented based on the buoy-measured data from February 2013 to December 2015 off Gopalpur at 15-m water depth. The mean seasonal significant wave height and mean wave period indicate that the occurrence of higher wave heights and wave periods is during the southwest monsoon period (June-September). 74% of the sea surface height variance in a year is a result of waves from 138 to 228° and 16% are from 48 to 138°. Strong inter-annual variability is observed in the monthly average wave parameters due to the occurrence of tropical cyclones. Due to the influence of the tropical cyclone Phailin, maximum significant wave height of 6.7 m is observed on 12 October 2013 and that due to tropical cyclone Hudhud whose track is 250 southwest of the study location is 5.84 m on 12 October 2014. Analysis revealed that a single tropical cyclone influenced the annual maximum significant wave height and not the annual average value which is almost same ( 1 m) in 2014 and 2015. The waves in the northwestern Bay of Bengal are influenced by the southwest and northeast monsoons, southern ocean swells and cyclones.

  1. Fire cue effects on seed germination of six species of northwestern Patagonian grasslands

    Science.gov (United States)

    Gonzalez, S. L.; Ghermandi, L.

    2012-09-01

    Postfire recruitment of seedlings has been attributed to a stimulation of germination by fire-related cues. The germination response to heat shock (80 °C - 5 min), smoke (60 min), the combination of both factors and no heat no smoke (control) was studied in six native species (two dominant grasses, two dominant shrubs and two annual fugitive herbs) of northwestern Patagonian grasslands. Seeds of the grasses Festuca pallescens and Stipa speciosa and the shrub Senecio bracteolatus (Asteraceae) germinated when they were exposed to heat shock, whereas seeds of the other shrub, Mulinum spinosum (Apiaceae), were killed by this fire cue. In grasses, probably the glume of caryopsis protected embryos from heat. Possibly, the seed size could explain the different responses of the two shrubs. Heat combined with smoke reduced seed germination for S. speciosa and S. bracteolatus. The heat could have scarified seeds and the longer exposure to smoke could have been toxic for embryos. The same treatment increased germination of the annual fugitive herb Boopis gracilis (Calyceraceae). We concluded that fire differentially affects the seedling recruitment of the studied species in the northwestern Patagonian grasslands.

  2. Post partum depression and the psychosocial predictors in first-time fathers from northwestern China.

    Science.gov (United States)

    Zhang, Yin-Ping; Zhang, Lu-Lu; Wei, Huan-Huan; Zhang, Yao; Zhang, Chun-Li; Porr, Caroline

    2016-04-01

    there is growing evidence that fathers also experience post partum depression (PPD). However, paternal PPD has been less studied than maternal PPD. Very few studies have investigated PPD in first-time fathers from northwestern China. the purpose of this study was to investigate the occurrence and predictors of depressive symptoms in first-time fathers from northwestern China. a longitudinal study was conducted involving 180 couples who were assessed at three time periods: 3 days, 2 weeks and 6 weeks after childbirth. Self-reported questionnaires including Edinburgh Postnatal Depression Scale (EPDS), Parenting Sense of Competence Scale (PSOC), and Kansas Marital Satisfaction Scale (KMSS) were administered to all participants during each time period. after childbirth 35 (21.1%) of the fathers at 3 days, 32 (20.4%) at 2 weeks and 20 (13.6%) at 6 weeks, indicated that they suffered from PPD. Paternal parental sense of competence, paternal marital satisfaction, and maternal depressive symptoms were among the main predictors for paternal PPD. the study results suggest that paternal PPD is a significant public health concern. Health professionals should focus attention on the psychological health among new fathers during the postpartum period; and, the psychosocial predictors should be considered and incorporated into clinical assessment and intervention of paternal PPD. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Towards a Caribou Habitat Management Strategy for Northwestern Ontario: Running the Gauntlet

    Directory of Open Access Journals (Sweden)

    Gerald D. Racey

    1996-01-01

    Full Text Available A management strategy for woodland caribou (Rangifer tarandus caribou habitat is being developed in northwestern Ontario. This strategy is based upon a set of draft Timber Management Guidelines for the Provision of Woodland Caribou Habitat. These guidelines recommend maintaining a sustainable supply of winter habitat within large tracts of old forest, protecting calving areas and minimizing human disturbance. Due to the large temporal and spatial scale of caribou habitat management, an ecosystem-based approach is recommended. Public response to the strategy shows a strong dichotomy between environmental and utilitarian values among all the major stakeholder groups. The major issues raised by the public include security of industrial wood supply, quality of the knowledge base, level of awareness of caribou, economic impacts on remote communities, concern about environmental impacts and silvicultural know-how. The government is responding to these concerns as the strategy evolves. Current emphasis is placed on increasing awareness of the public, training resource managers in caribou biology, management and habitat planning, implementing interim habitat management prescriptions and studying the potential impact on wood supply. The final direction for a northwestern Ontario strategy to conserve woodland caribou habitat has yet to be decided, although a commitment has been made to strive for the conservation of woodland caribou populations and their habitat.

  4. Molecular identification of tick-borne hemoparasites in equines from Northwestern Colombia

    Directory of Open Access Journals (Sweden)

    Yeison Agudelo-Ruíz

    2017-05-01

    Full Text Available Objetive. To detect and identify Anaplasmataceae agents and piroplasms in equines from the slaughterhouse “La Rinconada” at Rionegro municipality in Antioquia. Materials and Methods. A descriptive cross-sectional study was carried out on equines selected by convenience during a period of 2015. Information about species, sex, age and origin of the animals. Whole blood was collected for DNA extraction procedure, and a PCR targeting a 360bp of Anaplasmataceae 16S ribosomal gene and 450bp of 18S ribosomal gene of Piroplasm were used for detection. PCR amplicons selected were submitted to direct sequencing for identification of hemoparasites through genetic analysis. Results. 135 equine samples from Antioquia, Cordoba y Sucre were analyzed. 78% were horses, 16% were donkeys and 6% were mules. Anaplasmataceae agents were not detected in any sample, meanwhile 13% were positive to piroplasm PCR. Sequence analysis reveals the circulation of Theileria equi in northwestern Colombia. Conclusion. This work presents the first molecular evidence of at least three genotypes of T. equi in equines of northwestern Colombia.

  5. Survival of the Lhasa Terrane during its collision with Asia due to crust-mantle coupling revealed by ca. 114 Ma intrusive rocks in western Tibet

    Science.gov (United States)

    Wang, Qing; Zhu, Di-Cheng; Liu, An-Lin; Cawood, Peter A.; Liu, Sheng-Ao; Xia, Ying; Chen, Yue; Wang, Hao; Zhang, Liang-Liang; Zhao, Zhi-Dan

    2018-04-01

    Survival of the Lhasa Terrane during its drift across the Tethyan Ocean and subsequent collision with Asia was likely maintained by mechanical coupling between its ancient lithospheric mantle and the overlying crust. Evidence for this coupling is provided by geochronological and geochemical data from high-Mg dioritic porphyrite dikes that intruded into granodiorites with dioritic enclaves within the Nixiong Batholith in the western segment of the central Lhasa subterrane, southern Tibet. Zircon LA-ICP-MS U-Pb dating indicates synchronous emplacement of dioritic porphyrite dikes (113.9 ± 2 Ma), dioritic enclaves (113.9 ± 1 Ma), and host granodiorites (113.1 ± 2 Ma). The hornblende-bearing granodiorites are metaluminous to weakly peraluminous (A/CNK = 0.95-1.05) and belong to high-K calc-alkaline I-type granite. These rocks are characterized by low Mg# (37-43), negative zircon εHf(t) values (-6.8 to -1.2), and negative whole-rock εNd(t) values (-8.1 to -5.4), suggestive of derivation through anatexis of ancient lower crust. The two least-mixed or contaminated dioritic porphyrite dike samples have high MgO (8.46-8.74 wt%), high Mg# (69-70), and high abundances of compatible elements (e.g., Cr = 673-646 ppm, Ni = 177-189 ppm), which are close to those of primitive magma. They are high-K calc-alkaline and show negative whole-rock εNd(t) values (-1.9 to -1.2), indicating that these samples are most likely derived from the partial melting of ancient lithospheric mantle that was metasomatized by slab-derived fluids. The dioritic enclave samples are metaluminous high-K calc-alkaline and have varying negative whole-rock εNd(t) values (-7.8 to -3.7), which are interpreted as the result of magma mixing between the ancient lower crust-derived melts and asthenospheric mantle- (rather than lithospheric mantle-) derived melts. The Nd isotope mantle model ages of the least-mixed or contaminated high-Mg dioritic porphyrite dike samples (1.1-1.4 Ga) are close to the Nd isotope

  6. Grain-scale Sr isotope heterogeneity in amphibolite (retrograded UHP eclogite, Dabie terrane): Implications for the origin and flow behavior of retrograde fluids during slab exhumation

    Science.gov (United States)

    Guo, Shun; Yang, Yueheng; Chen, Yi; Su, Bin; Gao, Yijie; Zhang, Lingmin; Liu, Jingbo; Mao, Qian

    2016-12-01

    To constrain the origin and flow behavior of amphibolite-facies retrograde fluids during slab exhumation, we investigate the textures, trace element contents, and in situ strontium (Sr) isotopic compositions (using LA-MC-ICP-MS) of multiple types of epidote and apatite in the UHP eclogite and amphibolites from the Hualiangting area (Dabie terrane, China). The UHP epidote porphyroblasts in the eclogite (Ep-E), which formed at 28-30 kbar and 660-720 °C, contain high amounts of Sr, Pb, Th, Ba, and light rare earth elements (LREEs) and have a narrow range of initial 87Sr/86Sr ratios (0.70431 ± 0.00012 to 0.70454 ± 0.00010). Two types of amphibolite-facies epidote were recognized in the amphibolites. The first type of epidote (Ep-AI) developed in all the amphibolites and has slightly lower trace element contents than Ep-E. The Ep-AI has a same initial 87Sr/86Sr ratio range as the Ep-E and represents the primary amphibolite-facies retrograde product that is associated with an internally buffered fluid at 8.0-10.3 kbar and 646-674 °C. The other type of epidote (Ep-AII) occurs as irregular fragments, veins/veinlets, or reaction rims on the Ep-AI in certain amphibolites. Elemental X-ray maps reveal the presence of Ep-AI relics in the Ep-AII domains (appearing as a patchy texture), which indicates that Ep-AII most likely formed by the partial replacement of the Ep-AI in the presence of an infiltrating fluid. The distinctly lower trace element contents of Ep-AII are ascribed to element scavenging by a mechanism of dissolution-transport-precipitation during replacement. The Ep-AII in an individual amphibolite exhibits large intra- and inter-grain variations in the initial 87Sr/86Sr ratios (0.70493 ± 0.00030 to 0.70907 ± 0.00022), which are between those of the Ep-AI and granitic gneisses (wall rock of the amphibolites, 0.7097-0.7108). These results verify that the infiltrating fluid was externally derived from granitic gneisses. The matrix apatite in the amphibolites has

  7. Cryogenian alkaline magmatism in the Southern Granulite Terrane, India: Petrology, geochemistry, zircon U-Pb ages and Lu-Hf isotopes

    Science.gov (United States)

    Santosh, M.; Yang, Qiong-Yan; Ram Mohan, M.; Tsunogae, T.; Shaji, E.; Satyanarayanan, M.

    2014-11-01

    The Southern Granulite Terrane (SGT) in India preserves the records of the formation and recycling of continental crust from Mesoarchean through Paleoproterozoic to Neoproterozoic and Cambrian, involving multiple subduction-accretion-collision associated with major orogenic cycles. A chain of unmetamorphosed and undeformed alkaline magmatic intrusions occurs along the northern margin of the SGT aligned along paleo-suture zones. Here we investigate two representative plutons from this suite, the Angadimogar syenite (AM) and the Peralimala alkali granite (PM) through field, petrological, geochemical, zircon U-Pb and Lu-Hf studies. Magma mixing and mingling textures and mineral assemblages typical of alkaline rocks are displayed by these plutons. The whole-rock major and trace element data characterize their alkaline nature. In trace element discrimination diagrams, the AM rocks straddle between the VAG (volcanic-arc granites) and WPG (within plate granites) fields with most of the samples confined to the VAG field, whereas the PM rocks are essentially confined to the WPG field. The diversity in some of the geochemical features between the two plutons is interpreted to be the reflection of source heterogeneities. Most zircon grains from the AM and PM plutons display oscillatory zoning typical of magmatic crystallization although some grains, particularly those from the PM pluton, show core-rim structures with dark patchy zoned cores surrounded by irregular thin rims resulting from fluid alteration. The weighted mean 206Pb/238U ages of the magmatic zircons from three samples of the AM syenite are in the range of 781.8 ± 3.8 Ma to 798 ± 3.6 Ma and those from two samples of the PM alkali granite yield ages of 797.5 ± 3.7 Ma and 799 ± 6.2 Ma. A mafic magmatic enclave from the AM pluton shows weighted mean 206Pb/238U age of 795 ± 3.3 Ma. The AM and PM plutons also carry rare xeneocrystic zircons which define upper intercept concordia ages of 3293 ± 13 Ma and 2530

  8. Paleomagnetic constraints on early collisional deformation along the eastern margin of the Qiantang terrane (Tibetan plateau) at 50 and 37 Ma.

    Science.gov (United States)

    Roperch, Pierrick; Dupont-Nivet, Guillaume; Guillot, Stéphane; Goussin, Fanny; Huang, Wentao; Replumaz, Anne; Yang, Zhang; Guo, Zhaojie; Song, Bowen

    2017-04-01

    Ongoing controversies on the timing and latitude of the India-Asia collision with associated formation of the Tibetan plateau have major implications on geodynamic, climatic and biotic models. Rock paleomagnetic inclinations and declinations enable in principle to quantify respectively paleolatitudes and tectonic rotations. However, shallow paleomagnetic inclinations observed for most of the Cenozoic rocks across the active belts of Central Asia have been controversially interpreted as resulting from non dipolar geomagnetic fields, inclination flattening in the sedimentary data or large scale continental deformation. In addition tectonic rotations from the Eastern margin of Tibet may result from extrusion or dextral shear associated with implication on the early collision. We present new paleomagnetic results from two Cenozoic basins of the Eastern part of the Qiantang block characterized by two short-lived volcanic fields at 37-38Ma (Nangqian area) and 49-51Ma (Xialaxiu area). In the Xialaxiu area, we sampled the volcanic field near the town of Xialaxiu and red beds filling the Sangalaxiu basin 10 to 20km farther north. Results from the red beds after tilt correction (D=328.3°, I=34.3°, α95=7.6°) confirm the result (D=322.0°, I=32.3°, α95=9.5°) previously obtained by Cogne et al., (1999) but the age and nature of the characteristic magnetization are uncertain. The mean direction calculated from 21 sites in volcanic rocks provides a more reliable paleofield (D=11.9°, I=41.6°, α95=8.0°). Comparison with the expected direction for stable Eurasia suggest no rotation but significant post 50 Ma shortening north of the Qiantang block in agreement with results from the Lhasa terrane at the same age (56-47 Ma) (van Hinsbergen et al., 2012). In the Nangqian basin, paleomagnetic sites have been collected in red beds sediments, sills and dikes intruding the red bed sequence and in extrusive volcanic rocks mainly found on top of the sedimentary sequence. A well

  9. Recycling of Amazonian detrital zircons in the Mixteco terrane, southern Mexico: Paleogeographic implications during Jurassic-Early Cretaceous and Paleogene times

    Science.gov (United States)

    Silva-Romo, Gilberto; Mendoza-Rosales, Claudia Cristina; Campos-Madrigal, Emiliano; Morales-Yáñez, Axél; de la Torre-González, Alam Israel; Nápoles-Valenzuela, Juan Ivan

    2018-04-01

    In the northeastern Mixteco terrane of southern Mexico, in the Ixcaquixtla-Atzumba region, the recycling of Amazonian detrital zircons records the paleogeography during the Mesozoic period in the context of the breakup of Pangea, a phenomenon that disarticulated the Sanozama-La Mora paleo-river. The clastic units of southern Mexico in the Ayuquila, Otlaltepec and Zapotitlán Mesozoic basins, as well as in the Atzumba Cenozoic basin, are characterized by detrital zircon contents with ages specific to the Amazonian craton, ranging between 3040 and 1278 Ma. The presence of zircons of Amazonian affinity suggests a provenance by recycling from carrier units such as the La Mora Formation or the Ayú Complex. In the area, the Ayú and Acatlán complexes form the Cosoltepec block, a paleogeographic element that during Early Cretaceous time acted as the divide between the slopes of the paleo-Gulf of Mexico and the paleo-Pacific Ocean. The sedimentological characteristics of the Jurassic-Cenozoic clastic successions in the Ixcaquixtla-Atzumba region denote relatively short transport in braided fluvial systems and alluvial fans. In this way, several basins are recognized around the Cosoltepec block. At the southeastern edge of the Cosoltepec block, the Ayuquila and Tecomazúchil formations accumulated in the Ayuquila continental basin on the paleo-Pacific Ocean slope. On the other hand, within the paleo-Gulf of Mexico slope, in the Otlaltepec continental basin, the Piedra Hueca and the Otlaltepec formations accumulated. The upper member of the Santa Lucía Formation accumulated in a transitional environment on the southwestern shoulder of the Zapotitlán basin, as well as on the paleo-Gulf of Mexico slope. In the Ayuquila basin, a marine transgression is recognized that advanced from south to north during the Late Jurassic. At the northeastern edge of the Cosoltepec block, we propose that the Santa Lucía formation attests to a transgression from the paleo-Gulf of Mexico

  10. [Digenea of Haliaeetus albicilla (Linnaeus, 1758) and Pandion haliaetus (Linnaeus, 1758) from middle and north-western Poland].

    Science.gov (United States)

    Kalisińska, Elzbieta; Rzad, Izabella; Sitko, Jilji; Kavetska, Katarzyna M; Królaczyk, Katarzyna; Budis, Halina

    2008-01-01

    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.

  11. Amphibian and reptile responses to thinning and prescribed burning in mixed pine-hardwood forests of northwestern Alabama, USA

    Science.gov (United States)

    William B. Sutton; Yong Wang; Callie J. Schweitzer

    2013-01-01

    We evaluated the response of amphibians and reptiles to two levels of prescribed burning and three levels of thinning using a field experiment consisting of a before–after, control-impact, and factorial complete block design over a four year period in the William B. Bankhead National Forest located in northwestern Alabama. We captured 2643 individuals representing 47...

  12. Nematodes of the genus Amidostomum (Railliet et Henry, 1909) in wild ducks (Anatinae) of North-western Poland

    NARCIS (Netherlands)

    Kavetska, K.M.; Borgsteede, F.H.M.

    2005-01-01

    The study was aimed to quantify infections with nematodes of the genus Amidostomum in wild ducks of north-western Poland. The birds examined (282 individuals re-presenting 16 species) belonged to three, ecologically different, tribes: the Anatini, Aythyini and Mergini. The 923 individuals of

  13. Household-Level Determinants of Soil and Water Conservation Adoption Phases: Evidence from North-Western Ethiopian Highlands

    NARCIS (Netherlands)

    Teshome, Akalu; Graaff, de J.; Kassie, M.

    2016-01-01

    Soil and water conservation (SWC) practices have been promoted in the highlands of Ethiopia during the last four decades. However, the level of adoption of SWC practices varies greatly. This paper examines the drivers of different stages of adoption of SWC technologies in the north-western highlands

  14. Biodiversity and management of the Madrean Archipelago: The Sky Islands of southwestern United States and northwestern Mexico

    Science.gov (United States)

    Leonard H. DeBano; Peter H. Ffolliott; Alfredo Ortega-Rubio; Gerald J. Gottfried; Robert H. Hamre; Carleton B. Edminster

    1995-01-01

    This conference brought together scientists and managers from government, universities, and private organizations to examine the biological diversity and management challenges of the unique "sky island" ecosystems of the mountains of the southwestern United States and northwestern Mexico. Session topics included: floristic resources, plant ecology,...

  15. Vegetation patterns and abundances of amphibians and small mammals along small streams in a northwestern California watershed

    Science.gov (United States)

    Jeffrey R. Waters; Cynthia J. Zabel; Kevin S. McKelvey; Hartwell H. Welsh

    2001-01-01

    Our goal was to describe and evaluate patterns of association between stream size and abundances of amphibians and small mammals in a northwestern California watershed. We sampled populations at 42 stream sites and eight upland sites within a 100- watershed in 1995 and 1996. Stream reaches sampled ranged from poorly defined channels that rarely flowed to 10-m-wide...

  16. Rb-Sr ages of Precambrian sediments from the Ovruch mountain range, northwestern Ukraine (U.S.S.R.)

    International Nuclear Information System (INIS)

    Gorokhov, I.M.; Varshavskaya, E.S.; Kutyavin, E.P.; Clauer, N.; Drannik, A.S.

    1981-01-01

    A mineralogical and Rb-Sr geochronological study of Precambrian sediments and metasediments from the Ovruch mountain range (northwestern Ukraine) shows two distinct events: a slight metamorphism of the Belokorovichi Formation 1575 +- 30 Ma ago which precedes the deposition of the Zbranki Formation at 1389 +- 71 Ma (lambda 87 Rb = 1.42 x 10 -11 y -1 ). (Auth.)

  17. Manual versus Automated Narrative Analysis of Agrammatic Production Patterns: The Northwestern Narrative Language Analysis and Computerized Language Analysis

    Science.gov (United States)

    Hsu, Chien-Ju; Thompson, Cynthia K.

    2018-01-01

    Purpose: The purpose of this study is to compare the outcomes of the manually coded Northwestern Narrative Language Analysis (NNLA) system, which was developed for characterizing agrammatic production patterns, and the automated Computerized Language Analysis (CLAN) system, which has recently been adopted to analyze speech samples of individuals…

  18. CRED Gridded Bathymetry of Twin Banks and Northwest Nihoa Island (100-024) in the Northwestern Hawaiian Islands

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — File 100-024b is a 60-m ASCII grid of depth data collected near Twin Banks NW Nihoa in the Northwestern Hawaiian Islands as of May 2003. This grid has been produced...

  19. CRED Gridded Bathymetry along a transit to Nihoa Island (100-027) in the Northwestern Hawaiian Islands

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — File 100-027b is a 60-m ASCII grid of depth data collected near Transit to Nihoa in the Northwestern Hawaiian Islands as of May 2003. This grid has been produced as...

  20. CRED Gridded Bathymetry of Bank 66 and east French Frigate Shoals (100-020) in the Northwestern Hawaiian Islands

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — File 100-020b is a 60-m ASCII grid of depth data collected near Bank 66, East French Frigate Shoals in the Northwestern Hawaiian Islands as of May 2003. This grid...

  1. Northwestern University Initiative for Teaching NanoSciences (NUITNS): An Approach for Teaching Computational Chemistry to Engineering Undergraduate Students

    Science.gov (United States)

    Simeon, Tomekia; Aikens, Christine M.; Tejerina, Baudilio; Schatz, George C.

    2011-01-01

    The Northwestern University Initiative for Teaching Nanosciences (NUITNS) at nanohub.org Web site combines several tools for doing electronic structure calculations and analyzing and displaying the results into a coordinated package. In this article, we describe this package and show how it can be used as part of an upper-level quantum chemistry…

  2. Amount and distribution of coarse woody debris in pine ecosystems of north-western Spain, Russia and the United States

    Science.gov (United States)

    Celia Herrero; Olga Krankina; Vicente J. Monleon; Felipe. Bravo

    2014-01-01

    The quantity and characteristics of coarse woody debris (CWD) were examined in four distinct pine ecosystems of north-western (NW) Spain, NW Russia and the NW USA. Despite differences in species, ecological conditions and management histories, in all four ecosystems the mean snag volume was less than that of logs, most of the CWD mass was in an intermediate degree of...

  3. Clinical profile of parkinsonian disorders in the tropics: Experience at Kano, northwestern Nigeria

    Directory of Open Access Journals (Sweden)

    Owolabi Lukman Femi

    2012-01-01

    Full Text Available Background: No data exists on Parkinson′s disease (PD and secondary Parkinsonism in Northwestern Nigeria. This study was designed to create a database, document the clinical profile of PD in Kano, northwestern Nigerian, and compare this to prior observations within and outside Nigeria. Materials and Methods: A database was documented on prospective patients presenting consecutively to the Neurology out-patients clinic of the two tertiary health facilities in Kano northwestern Nigeria over a period of 4 years. Demographic and clinical data at presentation were documented for all patients. Cases were classified as PD or secondary Parkinsonism. The severity at presentation and at last visit was classified using the H and Y scale. Results: Over a period of 4 years, out 1153 a total of 96 patients comprising 74 males and 22 females were enrolled. Eighty (83.3% of them had clinically diagnosed PD while 16 (16.7% had clinical features compatible with secondary Parkinsonism. The mean age at onset of symptoms in the PD patients (mean 58.2 ± 6.72 yrs was more than in secondary Parkinsonism (mean 51.4 ± 10.04 and P = 0.001. There was male preponderance in both idiopathic Parkinsonism (PD (m:f = 3.2:1 and secondary Parkinsonism (m:f = 4.3:1. Out of the patients with secondary Parkinsonism, 10 (62.5% and 5 (31.3% had vascular Parkinsonism and drug-induced Parkinsonism, respectively. Duration of symptoms prior to presentation ranged between 3 months and 16 years. The mean (SD time interval from the onset of motor symptoms to diagnosis of PD was 3.6 ± 3.4 yrs and time interval for men and women (male 3.8 ± 3.7; female 2.8 ± 2.1; P = 0.249. Conclusions : Clinical profile of patients with PD and secondary Parkinsonism in Kano is similar to that from other populations within Nigeria and other developing countries. However, delayed presentation, less frequent family history, lower frequency of Young-onset PD as well as treatment challenges occasioned by

  4. Crustal and Upper Mantle Velocity Structure beneath Northwestern South America revealed by the CARMArray

    Science.gov (United States)

    Miao, W.; Cornthwaite, J.; Levander, A.; Niu, F.; Schmitz, M.; Dionicio, V.; Nader-Nieto, M. F.

    2017-12-01

    The Caribbean plate (CAR) is a fragment of the Farallon plate heavily modified by igneous processes that created the Caribbean large igneous province (CLIP) between 110 and 80 Ma.The CAR collided with and initiated subduction beneath northwestern South America plate (SA) at about 60-55 Ma as a narrow flat-slab subduction zone with an accretionary prism offshore, but no volcanic arc. Large scale regional tomography suggests that 1000 km of the CAR has been subducted (Van Benthem et al., 2013, JGR). The flat slab has caused Laramide-style basement uplifts of the Merida Andes, Sierra de la Perija, and Santa Marta ranges with elevations >5 km. The details of subduction geometry of the CAR plate beneath northeastern Colombia and northwestern Venezuela are complicated and remain unclear. The region of slab steepening lies below the triangular Maracaibo block (Bezada et al, 2010, JGR), bounded by major strike slip faults and currently escaping to the north over the CAR. Geodetic data suggests the this region has the potential for a magnitude 8+ earthquake (Bilham and Mencin, 2013, AGU Abstract). To better understand the subduction geometry, we deployed 65 broadband (BB) stations across northeastern Colombia and northwestern Venezuela in April of 2016. The 65 stations interweave with the 32 existing Colombian and Venezuelan BB stations, forming a 2-D array (hereafter referred to as CARMArray) with a station spacing of 35-100 km that covers an area of 600 km by 400 km extending from the Caribbean coast in Colombia to the interior plains of Venezuela. With data from the first year of operation, we have measured the Rayleigh wave phase velocities and Z/H ratios in the period range of 8-40 s using both ambient noise and earthquake data recorded by the CARMArray. We also generated Ps receiver functions from waveform data of teleseismic events recorded by the array. We then jointly inverted the three datasets to construct a 3-D S-wave velocity model beneath the array. We will

  5. Geochemistry, petrography, and zircon U-Pb geochronology of Paleozoic metaigneous rocks in the Mount Veta area of east-central Alaska: implications for the evolution of the westernmost part of the Yukon-Tanana terrane

    Science.gov (United States)

    Dusel-Bacon, Cynthia; Day, Warren C.; Aleinikoff, John N.

    2013-01-01

    We report the results of new mapping, whole-rock major, minor, and trace-element geochemistry, and petrography for metaigneous rocks from the Mount Veta area in the westernmost part of the allochthonous Yukon–Tanana terrane (YTT) in east-central Alaska. These rocks include tonalitic mylonite gneiss and mafic metaigneous rocks from the Chicken metamorphic complex and the Nasina and Fortymile River assemblages. Whole-rock trace-element data from the tonalitic gneiss, whose igneous protolith was dated by SHRIMP U–Pb zircon geochronology at 332.6 ± 5.6 Ma, indicate derivation from tholeiitic arc basalt. Whole-rock analyses of the mafic rocks suggest that greenschist-facies rocks from the Chicken metamorphic complex, a mafic metavolcanic rock from the Nasina assemblage, and an amphibolite from the Fortymile River assemblage formed as island-arc tholeiite in a back-arc setting; another Nasina assemblage greenschist has MORB geochemical characteristics, and another mafic metaigneous rock from the Fortymile River assemblage has geochemical characteristics of calc-alkaline basalt. Our geochemical results imply derivation in an arc and back-arc spreading region within the allochthonous YTT crustal fragment, as previously proposed for correlative units in other parts of the terrane. We also describe the petrography and geochemistry of a newly discovered tectonic lens of Alpine-type metaharzburgite. The metaharzburgite is interpreted to be a sliver of lithospheric mantle from beneath the Seventymile ocean basin or from sub-continental mantle lithosphere of the allochthonous YTT or the western margin of Laurentia that was tectonically emplaced within crustal rocks during closure of the Seventymile ocean basin and subsequently displaced and fragmented by faults.

  6. Flux and genesis of CO2 degassing from volcanic-geothermal fields of Gulu-Yadong rift in the Lhasa terrane, South Tibet: Constraints on characteristics of deep carbon cycle in the India-Asia continent subduction zone

    Science.gov (United States)

    Zhang, Lihong; Guo, Zhengfu; Sano, Yuji; Zhang, Maoliang; Sun, Yutao; Cheng, Zhihui; Yang, Tsanyao Frank

    2017-11-01

    Gulu-Yadong rift (GYR) is the longest extensional, NE-SW-trending rift in the Himalayas and Lhasa terrane of South Tibet. Many volcanic-geothermal fields (VGFs), which comprise intense hot springs, steaming fissures, geysers and soil micro-seepage, are distributed in the GYR, making it ideal area for studying deep carbon emissions in the India-Asia continent subduction zone. As for the northern segment of GYR in the Lhasa terrane, its total flux and genesis of CO2 emissions are poorly understood. Following accumulation chamber method, soil CO2 flux survey has been carried out in VGFs (i.e., Jidaguo, Ningzhong, Sanglai, Tuoma and Yuzhai from south to north) of the northern segment of GYR. Total soil CO2 output of the northern GYR is about 1.50 × 107 t a-1, which is attributed to biogenic and volcanic-geothermal source. Geochemical characteristics of the volcanic-geothermal gases (including CO2 and He) of the northern GYR indicate their significant mantle-derived affinities. Combined with previous petrogeochemical and geophysical data, our He-C isotope modeling calculation results show that (1) excess mantle-derived 3He reflects degassing of volatiles related with partial melts from enriched mantle wedge induced by northward subduction of the Indian lithosphere, and (2) the crust-mantle interaction can provide continuous heat and materials for the overlying volcanic-geothermal system, in which magma-derived volatiles are inferred to experience significant crustal contamination during their migration to the surface.

  7. Precipitation reconstruction for the northwestern Chinese Altay since 1760 indicates the drought signals of the northern part of inner Asia.

    Science.gov (United States)

    Chen, Feng; Yuan, Yujiang; Zhang, Tongwen; Shang, Huaming

    2016-03-01

    Based on the significant positive correlations between the regional tree-ring width chronology and local climate data, the total precipitation of the previous July to the current June was reconstructed since AD 1760 for the northwestern Chinese Altay. The reconstruction model accounts for 40.7 % of the actual precipitation variance during the calibration period from 1959 to 2013. Wet conditions prevailed during the periods 1764-1777, 1784-1791, 1795-1805, 1829-1835, 1838-1846, 1850-1862, 1867-1872, 1907-1916, 1926-1931, 1935-1943, 1956-1961, 1968-1973, 1984-1997, and 2002-2006. Dry episodes occurred during 1760-1763, 1778-1783, 1792-1794, 1806-1828, 1836-1837, 1847-1849, 1863-1866, 1873-1906, 1917-1925, 1932-1934, 1944-1955, 1962-1967, 1974-1983, 1998-2001, and 2007-2012. The spectral analysis of the precipitation reconstruction shows the existence of some cycles (15.3, 4.5, 3.1, 2.7, and 2.1 years). The significant correlations with the gridded precipitation dataset revealed that the precipitation reconstruction represents the precipitation variation for a large area of the northern part of inner Asia. A comparison with the precipitation reconstruction from the southern Chinese Altay shows the high level of confidence for the precipitation reconstruction for the northwestern Chinese Altay. Precipitation variation of the northwestern Chinese Altay is positively correlated with sea surface temperatures in tropical oceans, suggesting a possible linkage of the precipitation variation of the northwestern Chinese Altay to the El Niño-Southern Oscillation (ENSO) and the North Atlantic Oscillation (NAO). The synoptic climatology analysis reveals that there is the relationship between anomalous atmospheric circulation and extreme climate events in the northwestern Chinese Altay.

  8. Organochlorine contaminant and retinoid levels in blubber of common dolphins (Delphinus delphis) off northwestern Spain

    International Nuclear Information System (INIS)

    Tornero, Victoria; Borrell, Assumpcio; Aguilar, Alex; Forcada, Jaume; Lockyer, Christina

    2006-01-01

    The effect of age, sex, nutritive condition and organochlorine concentration on blubber retinoid concentrations was examined in 74 common dolphins incidentally caught off northwestern Spain. Age and blubber lipid content were strong determinants of the retinoid concentrations in males, while these variables did not account for the variation found in females. Retinoids were positively correlated with organochlorines in males and negatively in females. However, pollution levels were moderate and likely to be below threshold levels above that a toxicological response is to be expected. Thus, a cause-effect relationship between organochlorine and retinoid concentrations could not be properly established, and the observed correlation may be the result of an independent association of the two variables with age. Further research on the influence of the best predictor variables on retinoid dynamics is required to implement the use of retinoids as biomarkers of pollutant exposure in cetaceans. - Organochlorine contaminants and retinoids in common dolphins

  9. Marine debris accumulation in the Northwestern Hawaiian Islands: an examination of rates and processes.

    Science.gov (United States)

    Dameron, Oliver J; Parke, Michael; Albins, Mark A; Brainard, Russell

    2007-04-01

    Large amounts of derelict fishing gear accumulate and cause damage to shallow coral reefs of the Northwestern Hawaiian Islands (NWHI). To facilitate maintenance of reefs cleaned during 1996-2005 removal efforts, we identify likely high-density debris areas by assessing reef characteristics (depth, benthic habitat type, and energy regime) that influence sub-regional debris accumulation. Previously cleaned backreef and lagoonal reefs at two NWHI locations were resurveyed for accumulated debris using two survey methods. Accumulated debris densities and weights were found to be greater in lagoonal reef areas. Sample weight-based debris densities are extrapolated to similar habitats throughout the NWHI using a spatial 'net habitat' dataset created by generalizing IKONOS satellite derivatives for depth and habitat classification. Prediction accuracy for this dataset is tested using historical debris point data. Annual NWHI debris accumulation is estimated to be 52.0 metric tonnes. For planning purposes, individual NWHI atolls/reefs are allotted a proportion of this total.

  10. Analysis of the potential for wind energy production in northwestern Ontario

    Energy Technology Data Exchange (ETDEWEB)

    Brown, C K; Warne, D F

    1975-11-01

    A study of the feasibility of generating electric power from wind generators at remote sites in Northwestern Ontario has been carried out on behalf of the Ontario Ministry of Energy, with project management from Ontario Hydro. The work included (1) a survey of commercially available wind driven electric plant, both currently available and planned for production, (2) an analysis of existing wind data and preparation of an isovent map for Ontario showing annual mean wind speeds, (3) the selection of suitable sites for a demonstration unit and a prototype system, (4) the matching of available plant to the wind regimes to predict annual energy production, and (5) a systems analysis of pure diesel, hybrid wind/diesel and pure wind electric plants to determine the cost of power from the various alternatives.

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

    Science.gov (United States)

    Belknap, Daniel F.; Sandweiss, Daniel H.

    2014-06-01

    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.

  12. Numerical studies on the dynamics of the Northwestern Black Sea shelf

    Directory of Open Access Journals (Sweden)

    V. KOURAFALOU

    2004-06-01

    Full Text Available The Northwestern Black Sea shelf dynamics are studied with numerical simulations based on the Princeton Ocean Model. The study focus is on buoyancy and wind driven flows and on the transport and fate of low salinity waters that are introduced through riverine sources (the Danube, Dnestr and Dnepr Rivers, under the seasonal changes in atmospheric forcing. The study is part of the DANUBS project (NUtrient management in the DAnube basin and its impact on the Black Sea. The numerical simulations show that the coastal circulation is greatly influenced by river runoff and especially that of the Danube, which is dominant with monthly averaged values ranging from 5,000 m3 to 10,000 m3. The transport of low-salinity waters associated with the Danube runoff is greatly influenced by wind stress, topographic effects and basin-scale circulation patterns, such as changes in the position of the Rim Current.

  13. The gravity field and crustal structure of the northwestern Arabian Platform in Jordan

    Science.gov (United States)

    Batayneh, A. T.; Al-Zoubi, A. S.

    2001-01-01

    The Bouguer gravity field over the northwestern Arabian Platform in Jordan is dominated by large variations, ranging from -132 to +4 mGal. A study of the Bouguer anomaly map shows that the gravity field maintains a general north-northeasterly trend in the Wadi Araba-Dead Sea-Jordan Riff, Northern Highlands and Northeast Jordanian Limestone Area, while the remainder of the area shows north-northwesterly-trending gravity anomalies. Results of 2-D gravity modeling of the Bouguer gravity field indicate that the crustal thickness in Jordan is ˜ 38 km, which is similar to crustal thicknesses obtained from refraction data in northern Jordan and Saudi Arabia, and from gravity data in Syria.

  14. Validation of degree heating weeks as a coral bleaching index in the northwestern Pacific

    Science.gov (United States)

    Kayanne, Hajime

    2017-03-01

    Mass bleaching is the most significant threat to coral reefs. The United States National Oceanic and Atmospheric Administration monitors world sea surface temperature (SST) and releases warnings for bleaching based on degree heating weeks (DHW), which is the accumulation of temperature anomalies exceeding the monthly maximum mean SST for a given region. DHW values >4.0 °C-weeks are thought to induce bleaching, and those >8.0 °C-weeks are thought to result in widespread bleaching and some mortality. This study validates the effectiveness of DHW as a mass bleaching index by on-site historical observation at eight sites in the northwestern Pacific Ocean. The mass bleaching events occurred during different years at different sites. The recorded years of the bleaching events matched well with DHW values >8 °C-weeks, and the logistically projected probability of bleaching against DHW showed a positive relationship. DHW provides a reasonable threshold for bleaching.

  15. [Trophic webs of reef fishes in northwestern Cuba. I. Stomach contents].

    Science.gov (United States)

    Hernández, Ivet; Aguilar, Consuelo; González Sanón, Gaspar

    2008-06-01

    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.

  16. Outbreak of fatal childhood lead poisoning related to artisanal gold mining in northwestern Nigeria, 2010.

    Science.gov (United States)

    Dooyema, Carrie A; Neri, Antonio; Lo, Yi-Chun; Durant, James; Dargan, Paul I; Swarthout, Todd; Biya, Oladayo; Gidado, Saheed O; Haladu, Suleiman; Sani-Gwarzo, Nasir; Nguku, Patrick M; Akpan, Henry; Idris, Sa'ad; Bashir, Abdullahi M; Brown, Mary Jean

    2012-04-01

    In May 2010, a team of national and international organizations was assembled to investigate children's deaths due to lead poisoning in villages in northwestern Nigeria. Our goal was to determine the cause of the childhood lead poisoning outbreak, investigate risk factors for child mortality, and identify children data. Multivariate logistic regression techniques were used to determine risk factors for childhood mortality. We surveyed 119 family compounds. Of 463 children 45 µg/dL), and incidence of convulsions among children before death (82%) suggest that most of the recent childhood deaths in the two surveyed villages were caused by acute lead poisoning from gold ore-processing activities. Control measures included environmental remediation, chelation therapy, public health education, and control of mining activities.

  17. Bacillus thuringiensis in caterpillars and associated materials collected from protected tropical forests in northwestern Costa Rica.

    Science.gov (United States)

    Rodríguez-Sánchez, César; Sittenfeld, Ana; Janzen, Daniel H; Espinoza, Ana M

    2006-06-01

    Bacillus thuringiensis (Bt) synthesizes crystalline inclusions that are toxic to caterpillars (Lepidoptera) and other orders of invertebrates. Materials associated with 37 caterpillars from 16 species, collected while feeding on 15 different species of host plants in dry, cloud and rain forests located in the Area de Conservación Guanacaste in northwestern Costa Rica, were examined for the presence of Bt. From a total of 101 derived samples, 25 Bt isolates were cultured: 56% from host plant leaves, 8% from caterpillar guts and 36% from caterpillar fecal pellets. Bt was isolated from at least one sample in 38% of the systems constituted by the food plant, gut and fecal pellets corresponding to a single caterpillar. Four different morphologies of crystalline inclusions were observed, with bipyramidal and irregular crystal morphologies being the most prevalent.

  18. Experimental acidification of a poor fen in northwestern Ontario: Effects on emergence of Chironomidae (Diptera)

    Energy Technology Data Exchange (ETDEWEB)

    Rosenberg, D.M.; Wiens, A.P.; Bilyj, B. [Department of Fisheries and Oceans, Winnipeg, MB (Canada). Central and Arctic Region; Armstrong, L. [Department of Fisheries and Oceans, Winnipeg, MB (Canada). Central and Arctic Region

    1995-10-01

    The effects of experimental acidification and N fertilization on chironomid emergence from a poor fen in northwestern Ontario were studied from 1984 to 1989. Experimental treatments did not affect the numbers of chironomids emerging weekly, the timing of emergence, or the species composition of emergence during the study period. Weekly emergence counts were higher (P<0.05) from the periphery of the fen than the central part. Total seasonal emergence was higher from an area that was previously burned than from the rest of that swamp, though the difference was not statistically significant. Stability of species composition, despite experimental treatments and physiographic differences in the fen, may be a widespread characteristic of Canadian acidic peatlands. 7 tabs., 4 figs., 23 refs.

  19. Lithofacies Associations and Depositional Environments of the Neogene Molasse succession, Pishin Belt, northwestern Pakistan

    DEFF Research Database (Denmark)

    Kasi, Aimal K.; Kassi, Akhtar M.; Friis, Henrik

    The Pishin Belt is a NE-SW trending mixed flysch and molasse basin, situated at the northwestern part of Pakistan, bordered by Afghan Block of the Eurasian Plate in the west and Indian Plate in the east. Western boundary of the belt is marked by the well-known Chaman Transform Fault, whereas...... molasse successions of the Pishin Belt include the Dasht Murgha group, Malthanai formation and Bostan Formation; these are mostly composed of sandstone, claystone and conglomerate lithologies. Sandstones have been classified as lithic arenites and their QFL values suggest quartzolithic composition. Twelve...... southwestern extension of the Neo-Tethys) in the Early Miocene. Uplifted orogens of the Muslim Bagh-Zhob Ophiolite and marine successions of the Nisai and Khojak formations served as the major source terrains for the Miocene through Holocene molasse succession in the south and southeast verging successive...

  20. The collection of the Herpetological Museum of the University of Antioquia (northwestern Colombia).

    Science.gov (United States)

    Ortiz-Yusty, Carlos E; Daza, Juan M; Paez, Vivian P; Bock, Brian C

    2015-01-01

    Northwestern South America harbors one of the richest herpetofauna in the world. The connection among several biogeographic provinces along with climatic and orographic complexity makes this region an important contributor to the Neotropical biodiversity. Despite of this importance, the amphibian and reptile fauna in this area remains largely unknown as few herpetological collections has been made in recent decades. Motivated by this, the Herpetological Museum at the Universidad de Antioquia (Medellín, Colombia) has been increasing the collection in the last 16 years to better understand the herpetofaunal diversity and thus contribute to ecological, systematic, biogeographic and conservation research in the Neotropics. Here, we present the results of this effort and highlight how future collection will impact our understanding of the Neotropical herpetofauna.

  1. Acinetobacter Infection and Resistance Profile of Intensive Care Units In a City of Northwestern Anatolia

    Directory of Open Access Journals (Sweden)

    İsa Yıldız

    2016-09-01

    Full Text Available INTRODUCTION: Determination of suitable antibiotics in treatment of Acinetobacter infections is through the hospital ascertaining the resistance state to bacteria causing the problem. In this study, the evaluation of antibiotics sensitivity of Acinetobacter strains isolated as infection factor in patients hospitalized in intensive care units is aimed. METHODS: Acinetobacter strains isolated from the samples of patients hospitalized in the 2nd and 3rd Stage adult intensive care units of a province in in northwestern Anatolia have been studied. RESULTS: A total of 165 patients were included in the study. The most isolated samples were respiratory tract samples, blood and urine. The antibiotics which the factors were most sensitive were cholistin (66,1% gentamicin (22,4% and trimethoprim sulfamethoxazole (18,2%. DISCUSSION AND CONCLUSION: We face increasing resistance ratios in Acinetobacter strains. Necessary precautions should be taken for this.

  2. Upper Triassic spongiomorph and coral association dredged off the northwestern Australian shelf

    Science.gov (United States)

    Stanley, G. D.

    Upper Triassic corals and spongiomorphs dredged during BMR Cruise 95 from the Rowley Terrace, offshore Canning Basin of northwestern Australia, indicate possible new occurrences of reef facies. These are comparable to counterparts known from the Norhtern Limestone Alps of central Europe. A branching spongiomorph, represented by the genus Spongiomorpha sp. and two coral taxa, Pamiroseris rectilamellosa (Winkler) and Retiophyllia tellae (Stoppani), are reported herein. Collectively, these fossils indicate a Late Triassic (Noria-Rhaetian) age. Although different in taxonomic composition, the fauna compares with one previously reported from a Late Triassic Ocean Drilling Project reef site (site 764) on the Wombat Plateau, some 350 km to the west. The Rowley Terrace occurrences may represent an eastward extension of the Wombat reefs, developed along the rifted margin of Gondwana.

  3. Critical silvics of selected crop and competitor species in northwestern Ontario

    Energy Technology Data Exchange (ETDEWEB)

    Buse, L.J.

    1992-12-31

    This guide contains information on 25 plant species which may compete with conifer crop species and on six commercially important conifer species. The guide summarizes information on the autoecology of each species in the context of the Northwestern Ontario Forest Ecosystem Classification. In addition, it evaluates each of the potential competitors with respect to their competitive effects and mechanisms, their response to disturbance and silvicultural treatments (including their adaptation to forest canopy removal, cutting, mechanical site preparation, fire, and herbicides), and their potential value for wildlife. The guide similarly evaluates the six conifer species with respect to their response to competition and ability to respond to release. Summary tables enable quick comparison between species. This guide will assist forest resource managers in developing site-specific vegetation management strategies.

  4. Earthquake recurrence and magnitude and seismic deformation of the northwestern Okhotsk plate, northeast Russia

    Science.gov (United States)

    Hindle, D.; Mackey, K.

    2011-02-01

    Recorded seismicity from the northwestern Okhotsk plate, northeast Asia, is currently insufficient to account for the predicted slip rates along its boundaries due to plate tectonics. However, the magnitude-frequency relationship for earthquakes from the region suggests that larger earthquakes are possible in the future and that events of ˜Mw 7.5 which should occur every ˜100-350 years would account for almost all the slip of the plate along its boundaries due to Eurasia-North America convergence. We use models for seismic slip distribution along the bounding faults of Okhotsk to conclude that relatively little aseismic strain release is occurring and that larger future earthquakes are likely in the region. Our models broadly support the idea of a single Okhotsk plate, with the large majority of tectonic strain released along its boundaries.

  5. Current deformation rates and extrusion of the northwestern Okhotsk plate, northeast Russia

    Science.gov (United States)

    Hindle, D.; Fujita, K.; Mackey, K.

    2006-01-01

    Northeast Asia is a region of broad deformation resulting from the convergence of the Eurasian (EU) and North American (NA) plates. Part of this convergence has been suggested to be relieved by the extrusion and deformation of the Okhotsk plate (OK). Three models for the deformation of the seismically active northwestern corner of the Okhotsk plate, based on different modes of deformation partitioning, are calculated and compared to observations from GPS, seismicity, and geology. The results suggest that this region is being extruded southeastward and deforming internally by a mixture of pure contraction, ``smooth'' extrusion, and ``rigid'' extrusion. Calculated extrusion rates are ~3-5.5 mm/yr, comparable to estimates from geologic data, and internal deformation rates are ~3.0 × 10-9 yr -1. Internal deformation may be only partially accommodated by seismicity, but the short time span of seismic data leaves this subject to large uncertainty.

  6. New functionally dioecious bush tomato from northwestern Australia, Solanum ossicruentum, may utilize "trample burr" dispersal.

    Science.gov (United States)

    Martine, Christopher T; Cantley, Jason T; Frawley, Emma S; Butler, Alice R; Jordon-Thaden, Ingrid E

    2016-01-01

    A new Australian species of functionally dioecious bush tomato of Solanum subgenus Leptostemonum is described. Solanum ossicruentum Martine & J.Cantley, sp. nov., is thought to be allied with members of the problematic "Dioicum Complex" lineage, but differs in its short silvery indumentum, long calyx lobes, larger stature, and an unusual fruit morphology that may represent "trample burr" seed dispersal. The species occurs in a range extending from the eastern Kimberley in Western Australia to far northwestern Northern Territory and has been recognized for decades as a variant of Solanum dioicum W.Fitzg. Specimens of this species were previously referred to by D.E. Symon and others as Solanum dioicum 'Tanami.' Ex situ crossing studies and SEM images of inaperturate pollen grains produced in morphologically hermaphrodite flowers indicate that this taxon is functionally dioecious. The scientific name was chosen with the help of 150 seventh grade life science students from Pennsylvania, USA.

  7. Tectonic, volcanic, and climatic geomorphology study of the Sierras Pampeanas Andes, northwestern Argentina

    Science.gov (United States)

    Bloom, A. L.; Strecker, M. R.; Fielding, E. J.

    1984-01-01

    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.

  8. Hurricane storm surge and amphibian communities in coastal wetlands of northwestern Florida

    Science.gov (United States)

    Gunzburger, M.S.; Hughes, W.B.; Barichivich, W.J.; Staiger, J.S.

    2010-01-01

    Isolated wetlands in the Southeastern United States are dynamic habitats subject to fluctuating environmental conditions. Wetlands located near marine environments are subject to alterations in water chemistry due to storm surge during hurricanes. The objective of our study was to evaluate the effect of storm surge overwash on wetland amphibian communities. Thirty-two wetlands in northwestern Florida were sampled over a 45-month period to assess amphibian species richness and water chemistry. During this study, seven wetlands were overwashed by storm surge from Hurricane Dennis which made landfall 10 July 2005 in the Florida panhandle. This event allowed us to evaluate the effect of storm surge overwash on water chemistry and amphibian communities of the wetlands. Specific conductance across all wetlands was low pre-storm (marine habitats are resistant to the effects of storm surge overwash. ?? 2010 Springer Science+Business Media B.V.

  9. The collection of the Herpetological Museum of the University of Antioquia (northwestern Colombia

    Directory of Open Access Journals (Sweden)

    Carlos Ortiz-Yusty

    2015-02-01

    Full Text Available Northwestern South America harbors one of the richest herpetofauna in the world. The connection among several biogeographic provinces along with climatic and orographic complexity makes this region an important contributor to the Neotropical biodiversity. Despite of this importance, the amphibian and reptile fauna in this area remains largely unknown as few herpetological collections has been made in recent decades. Motivated by this, the Herpetological Museum at the Universidad de Antioquia (Medellín, Colombia has been increasing the collection in the last 16 years to better understand the herpetofaunal diversity and thus contribute to ecological, systematic, biogeographic and conservation research in the Neotropics. Here, we present the results of this effort and highlight how future collection will impact our understanding of the Neotropical herpetofauna.

  10. Beyond Positive Sciences : an Anthropological Approach to Market Analysis in North-Western Ghana

    Directory of Open Access Journals (Sweden)

    Dessein, JPG.

    2000-01-01

    Full Text Available Western science has often been thought of as an universally applicable, dominant and neutral knowledge system. Recently this view has been challenged by various scientists, who try to revalue the subjugated knowledge systems of local people by appreciating its characteristics. But this upgrading of endogenous knowledge often is but another example of the hegemonie position of Western science : it evaluates local situations with Western criteria, neglecting the cultural paradigms of the people involved. This article is a plea for a new multidisciplinary and intercultural research approach which takes as its foundation an understanding of the local culture and paradigms on which selected topics can be analysed, rather than a traditional disciplinary approach in which, afterwards, a foreign cultural component is being inscribed. This appeal is supported by material from a local market in North-western Ghana, where the Lobi peasants sell their harvest to the Wala traders.

  11. Influence of geologic structure on alluvial sedimentation in northwestern Yucca Flat, Nye County, Nevada

    International Nuclear Information System (INIS)

    Wagoner, J.L.

    1983-01-01

    Using downhole photography, alluvial sediments are described in 5 emplacement holes in northwestern Yucca Flat. The holes are located on or near the Grouse Canyon fan. The 3 most proximally located holes contain the coarsest sediments and display a general decrease in grain size in the downfan direction. The 2 most distally located holes contain fine-grained distal facies sediment in the upper parts of the holes and coarse-grained proximal facies gravels lower in the holes. The proximal gravels in the lower half of the sections were derived from the gravity high, a north-south-trending horst which was exposed early during the history of Yucca Flat basin. Alluvial sedimentation eventually exceeded uplift of the horst, which was buried by distal facies sediments, derived from the western basin margin

  12. Reproduction of mountain birch along a strong pollution gradient near Monchegorsk, Northwestern Russia

    International Nuclear Information System (INIS)

    Kozlov, Mikhail V.; Zvereva, Elena L.

    2004-01-01

    We explored effects of severe pollution on sexual reproduction of mountain birch, Betula pubescens subsp. czerepanovii, by counting catkins on sample branches and weighing both somatic and generative structures of both short and long shoots from birches growing at 21 sites around large nickel-copper smelter at Monchegorsk, Northwestern Russia. Proportion of reproducing trees, production of catkins, shoot and catkin weight, as well as the relative difference in weight of somatic structures of generative and vegetative shoots, were generally independent of pollution load; in 2003 birches growing in industrial barrens produced more catkins than birches growing in unpolluted forests. Thus, we found no support for the hypothesis that reproductive allocation should decrease with decrease in environmental capacity. Absence of adverse effects might indicate that long-lasting pollution impact already eliminated the most sensitive individuals from the affected birch populations. - Capsule: Variation in reproductive characteristics of mountain birch near the nickel-copper smelter at Monchegorsk is independent of pollution load

  13. Radioiodine retention in ovine thyroids in northwestern Greece following the reactor accident at Chernobyl

    International Nuclear Information System (INIS)

    Ioannides, K.G.; Pakou, A.A.; Papadopoulou, C.V.

    1991-01-01

    Iodine-131 concentrations were measured throughout the summer of 1986 in thyroids of lambs slaughtered at Ioannina (Northwestern Greece) following the accident at the Chernobyl nuclear reactor. During the survey, 40 thyroids were collected. The highest level of 131I detected was 2471 +/- 339 Bq per thyroid. The thyroids of 20 lambs did not contain detectable 131I concentrations, while the contamination content of the others was greatly variable. The transport of 131I from pasture to thyroids of lambs has been described through a simple model for the retention of 131I in the glands. The transfer coefficient fT, expressing the steady-state equilibrium, was estimated to be 564 +/- 270 kg-1 d. This result reflects the sensitivity of animal thyroids as biological radioiodine monitors

  14. Dispersion of radionuclides in the European north-western seas: observations and modelling

    International Nuclear Information System (INIS)

    Bailly du Bois, Pascal

    2013-01-01

    In this report for an Accreditation to supervise research (HDR), the author reports the use over 30 years by the Cherbourg-Octeville IRSN Laboratory of artificial radionuclides in solution in sea water as oceanographic markers. Such measurements on radio-markers which are soluble in sea water, enabled a better knowledge of dissolved substance displacements in north-western seas of Europe, notably the Channel, the North Sea, the Celtic Sea, and the Irish Sea. The author reports researches which aimed at studying the dispersion of radionuclides in seawater and their use as water mass markers, at validating hydrodynamic models of dispersion at different time-space scales, at the understanding and simulation of the sedimentary transport, and at studying the transfer to living species. These different topics give the document its structure [fr

  15. ALPINE MAGMATIC-METALLOGENIC FORMATIONS OF THE NORTHWESTERN AND CENTRAL DINARIDES

    Directory of Open Access Journals (Sweden)

    Jakob Pamić

    1997-12-01

    Full Text Available In the paper are presented basic geological, petrologieca1, geochemi-cal and mineral deposit data for five main magmatic-metallogenic formations of the northwestern and central Dinarides: (lThe Permo Triassic rifting related andesite-diorite formations; (2 The Jurassic-Lower Cretaceous accretionary (ophiolite formations; (3 The Upper Cretaceous-Paleogene subduction related basalt-rhyohite formations; (4 The Paleogene collisional granite formations, and (5 The Oligo-cene-Neogene postsubduction andesite formations. All these magmatic-metallogenic formations originated in different geotectonic settings during the Alpine evolution of the Dinaridic parts of thc Tethys and the postorogenic evolution of the Paratethys and the Pannonian Basin, respectively.

  16. How may CCS technology affect the electricity market in North-Western Europe?

    International Nuclear Information System (INIS)

    Seebregts, A.J.; Groenenberg, H.

    2008-11-01

    The EU electricity market is changing. Electricity demand in Europe is on the rise, the power plant fleet is aging, and a large share of the capacity will need to be replaced in the coming decades. An ambitious target has been formulated for the share of renewable energy, and CO2 prices are anticipated to increase. On top of this, CO2 Capture and Storage (CCS) has appeared as an important technology in the transition to a long term sustainable energy supply. This paper discusses the implications of all the fore-mentioned developments for the EU electricity market, with an emphasis on the Northwest European market. On the whole, electricity prices in the Northwestern part of Europe are anticipated to increase until 2020, but this may only partly be ascribed to the pending introduction of CCS

  17. Recolonization of wildlife on a coal strip-mine in northwestern New Mexico. [USA - New Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Ireland, T.T.; Wolters, G.L.; Schemnitz, S.D. (US Fish and Wildlife Service, Grand Junction, CO (United States))

    1994-03-01

    Recolonization by small mammals, reptiles, amphibians, and arthropods was studied in 1988 and 1989 on The Pittsburg and Midway Coal Mine in northwestern New Mexico. Sites reclaimed in 1979, 1982, and 1986 were compared with unmined sites for differences in animal composition and abundance. Wildlife components were compared with vegetative composition and physical ground features to determine if these influenced wildlife recolonization. The greater species richness of small mammals and the greater abundance of reptiles on the control treatment suggests that reclaimed sites are not providing suitable rock or woody cover for some species. Positive correlations of rock cover and wood cover with small-mammal species richness and the total reptile and amphibian captures indicate that placing rocks and wood cover on reclaimed sites may be beneficial to several small mammal, reptile, and amphibian species.

  18. Ethnic and geographic variations in HPV prevalence and genotype distribution in north-western Yunnan, China.

    Science.gov (United States)

    Baloch, Zulqarnain; Yuan, Tao; Wang, Binghui; Tai, Wenlin; Feng, Yue; Liu, Yanqing; Li, Xiao; Feng, Yue; Liu, Li; Zhang, A-mei; Wu, Xiaomei; Xia, Xueshan

    2016-03-01

    The prevalence and genotype distribution of human papillomavirus (HPV) vary throughout the world. To assess the prevalence and genotype distribution of HPV among three ethnic groups in two geographic locations in north-western Yunnan, we recruited 522 women in Shangri-le (n = 255) and Lijiang (n = 267). PCR amplification of HPV DNA was performed on cervical cells from these women using two consensus primer systems (MY09/11 and GP5/6). Amplified-HPV DNA was genotyped using the HPV GenoArray test. Geographically, the HPV prevalence was significantly higher (P = 0.002) among Shangri-le women than among Lijiang women. Infections with high-risk (HR)-HPV and with multiple HPV genotypes were also significantly more common (P = 0.001) among women in Shangri-le than women in Lijiang. Additionally, the prevalence of overall, HR-HPV, and single genotype HPV infections was significantly higher (P = 0.001) among Tibetan women than among Naxi and Han women. HPV-16 and HPV-33 were significantly more frequent in Shangri-le women compared with Lijiang (P = 0.006) women. In addition, HPV-16 (9.81%) and HPV-33 (5.88%) were significantly more prevalent in Tibetan women than in Naxi and Han women. Here, for the first time, we highlight the significant variation in the prevalence and genotype distribution of HPV in various populations in the north-western region of Yunnan Province. © 2015 Wiley Periodicals, Inc.

  19. The Land Cover Dynamics and Conversion of Agricultural Land in Northwestern Bangladesh, 1973-2003.

    Science.gov (United States)

    Pervez, M.; Seelan, S. K.; Rundquist, B. C.

    2006-05-01

    The importance of land cover information describing the nature and extent of land resources and changes over time is increasing; this is especially true in Bangladesh, where land cover is changing rapidly. This paper presents research into the land cover dynamics of northwestern Bangladesh for the period 1973-2003 using Landsat satellite images in combination with field survey data collected in January and February 2005. Land cover maps were produced for eight different years during the study period with an average 73 percent overall classification accuracy. The classification results and post-classification change analysis showed that agriculture is the dominant land cover (occupying 74.5 percent of the study area) and is being reduced at a rate of about 3,000 ha per year. In addition, 6.7 percent of the agricultural land is vulnerable to temporary water logging annually. Despite this loss of agricultural land, irrigated agriculture increased substantially until 2000, but has since declined because of diminishing water availability and uncontrolled extraction of groundwater driven by population pressures and the extended need for food. A good agreement (r = 0.73) was found between increases in irrigated land and the depletion of the shallow groundwater table, a factor affecting widely practiced small-scale irrigation in northwestern Bangladesh. Results quantified the land cover change patterns and the stresses placed on natural resources; additionally, they demonstrated an accurate and economical means to map and analyze changes in land cover over time at a regional scale, which can assist decision makers in land and natural resources management decisions.

  20. Risk assessment for yellow fever in western and North-Western provinces of Zambia

    Directory of Open Access Journals (Sweden)

    Olusegun A Babaniyi

    2015-01-01

    Full Text Available Background: North-Western and Western provinces of Zambia were reclassified as low-risk areas for yellow fever (YF. However, the current potential for YF transmission in these areas is unclear. Aims: To determine the current potential risk of YF infection. Setting and Design: A cross sectional study was conducted in North-Western and Western provinces of Zambia. Materials and Methods: Samples were tested for both YF virus-specific IgG and IgM antibodies by the ELISA and YF virus confirmation was done using Plaque Reduction Neutralization Test. The samples were also tested for IgG and IgM antibodies against other flaviviruses. Results: Out of the 3625 respondents who participated in the survey, 46.7% were males and 9.4% were aged less than 5 years. Overall, 58.1% of the participants slept under an impregnated insecticide-treated net and 20.6% reported indoor residual spraying of insecticides. A total of 616 (17.0% samples were presumptive YF positive. The prevalence for YF was 0.3% for long-term infection and 0.2% for recent YF infection. None of the YF confirmed cases had received YF vaccine. Prevalence rates for other flaviviruses were 149 (4.1% for Dengue, 370 (10.2% for West Nile and 217 (6.0% for Zika. Conclusion: There is evidence of past and recent infection of YF in both provinces. Hence, they are at a low risk for YF infection. Yellow fever vaccination should be included in the EPI program in the two provinces and strengthen surveillance with laboratory confirmation.

  1. Recent Climate Changes in Northwestern Qaidam Basin Inferred from Geothermal Gradients

    Science.gov (United States)

    Liu, J.; Zhang, T.

    2014-12-01

    Temperature perturbations under the ground surface are direct thermal response to ground surface temperature changes. Thus ground surface temperature history can be reconstructed from borehole temperature measurements using borehole paleothermometry inversion method. In this study, we use seven borehole temperature profiles to reconstruct the ground surface temperature variation of the past 500 years of the Qaidam basin, northwestern China. Borehole transient temperature measurement from seven sites in northwestern Qaidam basin were separated from geothermal gradients and analyzed by functional space inversion method to determine past ground surface temperature variations in this region. All temperature profiles show the effects of recent climatic disturbances. Inversion shows an overall increase in ground surface temperature by an averaged 1.2℃ (-0.11~2.21℃) during the last 500 years. Clear signs of a cold period between 1500 and 1900 A.D., corresponding to the Little Ice Age, have been found. Its coldest period was between 1780~1790 A.D. with the ground surface temperature of 5.4℃. During the 19th and the 20th century, reconstructed ground surface temperature shows a rising trend, and in the late 20th century, the temperature started to decrease. However, the highest temperature in 1990s broke the record of the past 500 years. This reconstructed past ground surface temperature variation is verified by the simulated annual surface air temperature computed by EdGCM and the cooling trend is also confirmed by other reconstruction of winter half year minimum temperatures using tree rings on the northeastern Tibetan Plateau.

  2. DNA barcode assessment of Ceramiales (Rhodophyta) in the intertidal zone of the northwestern Yellow Sea

    Science.gov (United States)

    Du, Guoying; Wu, Feifei; Guo, Hao; Xue, Hongfan; Mao, Yunxiang

    2015-05-01

    A total of 142 specimens of Ceramiales (Rhodophyta) were collected each month from October 2011 to November 2012 in the intertidal zone of the northwestern Yellow Sea. These specimens covered 21 species, 14 genera, and four families. Cluster analyses show that the specimens had a high diversity for the three DNA markers, namely, partial large subunit rRNA gene (LSU), universal plastid amplicon (UPA), and partial mitochondrial cytochrome c oxidase subunit I gene (COI). No intraspecific divergence was found in our collection for these markers, except for a 1-3 bp divergence in the COI of Ceramium kondoi, Symphyocladia latiuscula, and Neosiphonia japonica. Because short DNA markers were used, the phylogenetic relationships of higher taxonomic levels were hard to evaluate with poor branch support. More than half species of our collection failed to find their matched sequences owing to shortage information of DNA barcodes for macroalgae in GenBank or BOLD (Barcode of Life Data) Systems. Three specimens were presumed as Heterosiphonia crispella by cluster analyses on DNA barcodes assisted by morphological identification, which was the first record in the investigated area, implying that it might be a cryptic or invasive species in the coastal area of northwestern Yellow Sea. In the neighbor-joining trees of all three DNA markers, Heterosiphonia japonica converged with Dasya spp. and was distant from the other Heterosiphonia spp., implying that H. japonica had affinities to the genus Dasya. The LSU and UPA markers amplified and sequenced easier than the COI marker across the Ceramiales species, but the COI had a higher ability to discriminate between species.

  3. Biofilm inhibition activity of traditional medicinal plants from Northwestern Argentina against native pathogen and environmental microorganisms

    Directory of Open Access Journals (Sweden)

    Cintia Mariana Romero

    Full Text Available Abstract: INTRODUCTION: Plants have been commonly used in popular medicine of most cultures for the treatment of disease. The in vitro antimicrobial activity of certain Argentine plants used in traditional medicine has been reported. The aim of this study was to investigate the antimicrobial, anti-biofilm, and anti-cell adherence activities of native plants (Larrea divaricata, Tagetes minuta, Tessaria absinthioides, Lycium chilense, and Schinus fasciculatus collected in northwestern Argentina. METHODS: The activities of the five plant species were evaluated in Bacillus strains and clinical strains of coagulase-negative Staphylococcus isolated from northwestern Argentina and identified by 16S rDNA. RESULT: Lycium chilense and Schinus fasciculatus were the most effective antimicrobial plant extracts (15.62µg/ml and 62.50µg/ml for Staphylococcus sp. Mcr1 and Bacillus sp. Mcn4, respectively. The highest (66% anti-biofilm activity against Bacillus sp. Mcn4 was observed with T. absinthioides and L. divaricate extracts. The highest (68% anti-biofilm activity against Staphylococcus sp. Mcr1 was observed with L. chilense extract. T. minuta, T. absinthioides, and L. divaricata showed percentages of anti-biofilm activity of between 55% and 62%. The anti-adherence effects of T. minuta and L. chilense observed in Bacillus sp. Mcn4 reflected a difference of only 22% and 10%, respectively, between anti-adherence and biofilm inhibition. Thus, the inhibition of biofilm could be related to cell adherence. In Staphylococcus sp. Mcr1, all plant extracts produced low anti-adherence percentages. CONCLUSION: These five species may represent a source of alternative drugs derived from plant extracts, based on ethnobotanical knowledge from northwest Argentina.

  4. First genotyping of Blastocystis sp. in dairy, meat, and cashmere goats in northwestern China.

    Science.gov (United States)

    Song, Jun-Ke; Yin, Yan-Ling; Yuan, Ya-Jie; Tang, Huan; Ren, Guan-Jing; Zhang, Hui-Jun; Li, Zi-Xuan; Zhang, Yan-Ming; Zhao, Guang-Hui

    2017-12-01

    Blastocystis is one of the most common parasites inhabiting in small intestines of human and animals. Although its pathogenicity has been remaining controversial, the possibility of zoonotic transmission between human and animals was recognized. The goat was one of the most important economic animals supplying people with cashmere, meat, and dairy products. However, few studies were to investigate Blastocystis infection in goats. A total of 789 faecal specimens of goats (including 362 of dairy, 193 of meat and 234 of cashmere goats) were collected from multiple regions of Shaanxi province in northwestern China to investigate the colonization frequency and subtypes of Blastocystis, and to assess the zoonotic potential of these goats. The respective colonization frequencies of Blastocystis in dairy, meat and cashmere goats were 54.1% (196/362), 40.4% (78/193) and 78.6% (184/234). The prevalence of Blastocystis in pre-weaned (0-2-month) goats was significantly lower than that in goats of other age groups, and the highest colonization was observed in goats of 7-11-month age group. Sequence analysis of Blastocystis positive samples indicated the presence of seven subtypes in these goats, including six known subtypes (STs1, 3, 4, 5, 10, 14) and one possible novel subtype (isolate Sd26), with the subtype 10 as the predominant one. Additionally, zoonotic subtypes were found in dairy (ST1, ST3 and ST5) and cashmere (ST4 and ST5) goats, but not detected in meat goats. These results showed that Blastocystis is highly prevalent, widely distributed and genetically diverse in goats in Shaanxi province, northwestern China, and zoonotic potential of dairy and cashmere goats to transmit Blastocystis. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Occurrence of phosphorus in groundwater and surface water of northwestern Mississippi

    Science.gov (United States)

    Welch, Heather L.; Kingsbury, James A.; Coupe, Richard H.

    2010-01-01

    Previous localized studies of groundwater samples from the Mississippi River Valley alluvial (MRVA) aquifer have demonstrated that dissolved phosphorus concentrations in the aquifer are much higher than the national background concentration of 0.03 milligram per liter (mg/L) found in 400 shallow wells across the country. Forty-six wells screened in the MRVA aquifer in northwestern Mississippi were sampled from June to October 2010 to characterize the occurrence of phosphorus in the aquifer, as well as the factors that might contribute to high dissolved phosphorus concentrations in groundwater. Dissolved phosphorus concentrations ranged from 0.12 to 1.2 mg/L with a median concentration of 0.62 mg/L. The predominant subunit of the MRVA aquifer in northwestern Mississippi is the Holocene alluvium in which median dissolved phosphorus concentrations were higher than the Pleistocene valley trains deposits subunit. Highest phosphorus concentrations occurred in water from wells located along the Mississippi River. A general association between elevated phosphorus concentrations and dissolved iron concentrations suggests that reducing conditions that mobilize iron in the MRVA aquifer also might facilitate transport of phosphorus. Using baseflow separation to estimate the contribution of baseflow to total streamflow, the estimated contribution to the total phosphorus load associated with baseflow at the Tensas River at Tendal, LA, and at the Bogue Phalia near Leland, MS, was 23 percent and 8 percent, respectively. This analysis indicates that elevated concentrations of dissolved phosphorus in the MRVA aquifer could be a possible source of phosphorus to streams during baseflow conditions. However, the fate of phosphorus in groundwater discharge and irrigation return flow to streams is not well understood.

  6. Low durophagous predation on Toarcian (Early Jurassic ammonoids in the northwestern Panthalassa shelf basin

    Directory of Open Access Journals (Sweden)

    Yusuke Takeda

    2015-12-01

    Full Text Available Predatory shell breakage is known to occur occasionally on the ventrolateral portion of the body chamber in Mesozoic ammonoids. Here we report, for the first time, quantitative data of shell breakage in large ammonoid samples that were recovered from the lower Toarcian (Lower Jurassic strata in the Toyora area, western Japan. The strata yielding the ammonoid samples consisted mostly of well-laminated, bituminous black shale that was deposited in an oxygen-depleted shelf basin of the northwestern Panthalassa, under the influence of the early Toarcian oceanic anoxic event. Among a total of 1305 specimens from 18 localities, apparent shell breakage was recognised in 35 specimens belonging to 7 genera, resulting in only a 2.7% frequency of occurrence relative to the total number of specimens. The breakage occurs mostly on the ventrolateral side of the body chamber with a complete shell aperture. This fact, as well as the low energy bottom condition suggested for the ammonoid-bearing shale, indicate that the shell breaks observed in the examined ammonoids were not produced by non-biological, post-mortem biostratinomical processes but were lethal injuries inflicted by nektonic predators such as reptiles, jawed fishes, coleoids, nautiloids, and carnivorous ammonoids with calcified rostral tips in their upper and lower jaws. Similar predatory shell breaks on the ventrolateral side of the body chamber have been found in contemporaneous ammonoid assemblages of the Tethys Realm, with a much higher frequency of occurrence than in the examined samples from the northwestern Panthalassa, suggesting a weaker durophagous predation pressure on ammonoids in the latter bioprovince.

  7. Aquatic Coleoptera assemblages in protected wetlands of North-western Spain

    Directory of Open Access Journals (Sweden)

    Amaia Pérez-Bilbao

    2014-02-01

    Full Text Available Wetlands are diverse and productive ecosystems endangered by human pressure, which degradation implies a biodiversity loss worldwide. Among the biological assemblages of these habitats, aquatic Coleoptera is one of the most diverse and useful groups when assessing the ecological conditions of the ecosystems they inhabit. The aims of the present study were to analyze the diversity and composition of aquatic Coleoptera assemblages in 24 wetlands protected by the Natura 2000 network of North-western Spain and the influence of environmental variables on the distribution of species, in order to detect differences between the different types of standing water habitats. A total of 11,136 individuals of 105 species belonging to 12 families of aquatic Coleoptera (Gyrinidae, Haliplidae, Noteridae, Paelobiidae, Dytiscidae, Helophoridae, Hydrochidae, Hydrophilidae, Hydraenidae, Scirtidae, Elmidae and Dryopidae were collected. In general, wetlands presented high richness and diversity values, Dytiscidae and Hydrophilidae having the highest species richness. Most of recorded species have a wide biogeographical distribution and only 12 endemic ones were captured. Cluster and Non-Metric Multi-Dimensional Scaling (NMDS analyses showed the clustering of the studied ponds and lagoons in four groups based on biological data. In general, the wetlands of each group seem to have distinct aquatic Coleoptera faunas, as showed by the most representative species. A combination of altitude, SST and hydroperiod was the best explaining factor of the distribution of the species throughout the study area. This study shows the high biodiversity of standing water habitats in North-western Spain and the usefulness of water beetles in establishing habitat typologies.

  8. Impact of Two Intense Dust Storms on Aerosol Characteristics and Radiative Forcing over Patiala, Northwestern India

    Directory of Open Access Journals (Sweden)

    Deepti Sharma

    2012-01-01

    Full Text Available Impact of dust storms on the aerosol characteristics and radiative forcing over Patiala, northwestern India has been studied during April-June of 2010 using satellite observations and ground-based measurements. Six dust events (DE have been identified during the study period with average values of Aqua-MODIS AOD550 and Microtops-II AOD500 over Patiala as 1.00±0.51 and 0.84±0.41, respectively while Aura-OMI AI exhibits high values ranging from 2.01 to 6.74. The Ångström coefficients α380–870 and β range from 0.12 to 0.31 and 0.95 to 1.40, respectively. The measured spectral AODs, the OPAC-derived aerosol properties and the surface albedo obtained from MODIS were used as main inputs in SBDART model for the calculation of aerosol radiative forcing (ARF over Patiala. The ARF at surface (SRF and top of atmosphere (TOA ranges from ∼−50 to −100 Wm−2 and from ∼−10 to −25 Wm−2, respectively during the maximum of dust storms. The radiative forcing efficiency was found to be −66 Wm−2AOD−1 at SRF and −14 Wm−2AOD−1 at TOA. High values of ARF in the atmosphere (ATM, ranging between ∼+40 Wm−2 and +80.0 Wm−2 during the DE days, might have significant effect on the warming of the lower and middle atmosphere and, hence, on climate over northwestern India.

  9. Cultural Transmission of Traditional Knowledge in two populations of North-western Patagonia

    Directory of Open Access Journals (Sweden)

    Lozada Mariana

    2008-12-01

    Full Text Available Abstract Background In the present study we have investigated the cultural transmission of two types of traditional plant knowledge in two communities of North-western Patagonia, Argentina. In the Pilcaniyeu community, we studied the transmission of traditional knowledge related to horticultural practices in home-gardens, greenhouses and gardens; while in the community of Cuyin Manzano, we studied wild plant gathering customs. Methods Ethnobotanical fieldwork was conducted by means of semi-structured interviews, in which we investigated which plants are used, at what life history phase was learned, modes of transmission and who the principal transmitters were in childhood and adulthood. In both communities, each of this three aspects related to cultural transmission were categorized and the frequencies of each category were obtained. The total number of species recorded in each community was also calculated. Frequencies were analyzed with the Chi-square test of independence. Results and discussion In both communities, transmission of traditional plant knowledge begins at an early age, as a family custom, in which women play a predominant role. Wild plant use and horticultural knowledge continue to be learned during adulthood. This was particularly registered associated with horticultural learning, which receives greater influence from extension agents who are introducing new practices and technology. This outside influence, which implies novelty, could imply syncretism but also traditional knowledge loss. Conclusion Given the remarkable acculturation processes occurring at present in rural communities of Northwestern Patagonia, it might be of vital importance to document traditional knowledge of ancient practices. Moreover, it could be interesting to share our results with both populations in order to encourage participatory activities within the communities which could enhance traditional knowledge horizontal transmission, particularly among

  10. Groundtruthing Notes and Miscellaneous Biological Datasets from Coral Ecosystems Surveys from the Northwestern Hawaiian Islands Rapid Reef Assessment and Monitoring Program of 2000-2002 (NODC Accession 0001448)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Northwestern Hawaiian Islands Coral Reef Assessment and Monitoring Program (NOWRAMP) began in 2000 with the mission to rapidly evaluate and map the shallow water...

  11. CRED 20 m Gridded bathymetry and IKONOS estimated depths of Northampton Seamounts to Laysan Island, Northwestern Hawaiian Islands, USA (NetCDF format)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Gridded bathymetry and IKONOS estimated depths of the shelf and slope environments of Northampton Seamounts to Laysan Island, Northwestern Hawaiian Islands, Hawaii,...

  12. CRED 60 m Gridded bathymetry and IKONOS estimated depths of UTM Zone 2, Northwestern Hawaiian Islands, USA (NetCDF format)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Gridded bathymetry and IKONOS estimated depths of the shelf and slope environments of the Northwestern Hawaiian Islands, USA within UTM Zone 2. Bottom coverage was...

  13. 2002 EM1002 and EM120 Multibeam Sonar Data from Cruise R/V Kilo Moana KM-02-06 - Northwestern Hawaiian Islands

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — EM1002 and EM120 multibeam Data were collected in October/November 2002 aboard R/V Kilo Moana between Kauai Island and Lisianski Island in the Northwestern Hawaiian...

  14. CRED 60 m Gridded bathymetry and IKONOS estimated depths of UTM Zone 3, Northwestern Hawaiian Islands, USA (netCDF format)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Gridded bathymetry and IKONOS estimated depths of the shelf and slope environments of the Northwestern Hawaiian Islands, USA within UTM Zone 3. Bottom coverage was...

  15. CRED 60 m Gridded bathymetry and IKONOS estimated depths of UTM Zone 1, Northwestern Hawaiian Islands, USA (NetCDF format)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Gridded bathymetry and IKONOS estimated depths of the shelf and slope environments of the Northwestern Hawaiian Islands, USA within UTM Zone 1. Bottom coverage was...

  16. Water Quality Data from Two Agricultural Drainage Basins in Northwestern Indiana and Northeastern Illinois: I. Lagrangian and Synoptic Data, 1999-2002

    National Research Council Canada - National Science Library

    Antweiler, Ronald C; Smith, Richard L; Voytek, Mary A; Boehlke, John-Karl; Richards, Kevin D

    2004-01-01

    Methods of data collection and results of analyses are presented for Lagrangian and synoptic water-quality data collected from two agricultural drainages, the Iroquois River in northwestern Indiana...

  17. CRED 20 m Gridded bathymetry and IKONOS estimated depths of Northampton Seamounts to Laysan Island, Northwestern Hawaiian Islands, USA (Arc ASCII format)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Gridded bathymetry and IKONOS estimated depths of the shelf and slope environments of Northampton Seamounts to Laysan Island, Northwestern Hawaiian Islands, Hawaii,...

  18. Increase in Export Production in the Marginal Seas of the Northwestern Pacific in Response to Anthropogenic N Input

    Science.gov (United States)

    Lee, K.; Ko, Y. H.; Moon, J. Y.

    2017-12-01

    The relative abundance of nitrate (N) over phosphorus (P) has increased significantly over the period since 1980 in the marginal seas (Yellow, East China and East seas) bordering the northwestern Pacific Ocean, located downstream of the populated and industrialized Asian continent. Analysis of datasets for anthropogenic N input, satellite chlorophyll-a (Chl-a), and seawater nutrient data ( 200,000 data points) reveal that transport of N originating from China has been responsible for enhancements of Chl-a in the marginal seas of the northwestern Pacific Ocean. In particular, the contribution of anthropogenic N to new production in these marginal seas is expected to grow considerably in the coming decades. This anthropogenically driven increase in the N content may potentially lead to a long-term change of these marginal seas from being N-limited to P-limited.

  19. THE POLLUTION OF THE BOTTOM SEDIMENTSIN THE NORTH-WESTERN PART OF THE CASPIAN SEA HYDROCARBONS AND PERSISTENT ORGANIC POLLUTANTS

    Directory of Open Access Journals (Sweden)

    E. V. Ostrovskaya

    2014-01-01

    Full Text Available Aim. The pollution of the bottom sediments in the north-western part of the Caspian sea hydrocarbons and persistent organic pollutants. Location.Caspian Sea. Methods. The materials for this article is based on the results of monitoring conducted in 2012-2013 years. Results. Sediments in the north-western part of the Caspian Sea as a whole slightly contaminated YV and SOZ, although localized areas of high pollution are marked, especially characteristic of the Middle Caspian. Mainconclusions.The studies were showed, PAY in the sediments are mixed genesis, but most of them, in all probability, were petroleum origin. The not weathered hydrocarbons are presented in sediments, which indicates to the presence of the local sources of the fresh oil pollution on the surveyed area.

  20. Divergent population genetic structure of the endangered Helianthemum (Cistaceae) and its implication to conservation in northwestern China

    Science.gov (United States)

    Zhihao Su; Bryce A. Richardson; Li Zhuo; Xiaolong Jiang

    2017-01-01

    Population genetic studies provide a foundation for conservation planning, especially for endangered species. Three chloroplast SSRs (mtrnSf-trnGr, mtrnL2-trnF, and mtrnL5-trnL3) and the internal transcribed spacer were used to examine the population structure of Helianthemum in northwestern China. A total of 15 populations of the genus were collected. Nine chloroplast...

  1. Pharmacy Professionals' Dispensing Practice, Knowledge, and Attitude towards Emergency Contraceptives in Gondar Town, Northwestern Ethiopia: A Cross-Sectional Study

    OpenAIRE

    Belachew, Sewunet Admasu; Yimenu, Dawit Kumilachew; Gebresillassie, Begashaw Melaku

    2017-01-01

    Background. Pharmacy professionals, as the most available members of medical team, have an important role in educating patients about the effective and appropriate use of contraceptives. The purpose of this study was to assess pharmacy professionals’ dispensing practice, knowledge, and attitude towards emergency contraceptives use in Gondar town, northwestern Ethiopia. Methods. An institution based cross-sectional study was employed from May 14 to June 14, 2016, on 60 pharmacy professionals, ...

  2. Circumglobal wave train and the summer monsoon over northwestern India and Pakistan: the explicit role of the surface heat low

    Energy Technology Data Exchange (ETDEWEB)

    Saeed, Sajjad [Max Planck Institute for Meteorology, Hamburg (Germany); International Max Planck Research School on Earth System Modeling, Hamburg (Germany); Pakistan Meteorological Department, Islamabad (Pakistan); Mueller, Wolfgang A.; Hagemann, Stefan; Jacob, Daniela [Max Planck Institute for Meteorology, Hamburg (Germany)

    2011-09-15

    This study examines the influence of the mid-latitude circulation on the surface heat low (HL) and associated monsoon rainfall over northwestern India and Pakistan using the ERA40 data and high resolution (T106L31) climate model ECHAM5 simulation. Special emphasis is given to the surface HL which forms over Pakistan and adjoining areas of India, Iran and Afghanistan during the summer season. A heat low index (HLI) is defined to depict the surface HL. The HLI displays significant correlations with the upper level mid-latitude circulation over western central Asia and low level monsoon circulation over Arabian Sea and acts as a bridge connecting the mid-latitude wave train to the Indian summer monsoon. A time-lagged singular value decomposition analysis reveals that the eastward propagation of the mid-latitude circumglobal wave train (CGT) influences the surface pressure anomalies over the Indian domain. The largest low (negative) pressure anomalies over the western parts of the HL region (i.e., Iran and Afghanistan) occur in conjunction with the upper level anomalous high that develops over western-central Asia during the positive phase of the CGT. The composite analysis also reveals a significant increase in the low pressure anomalies over Iran and Afghanistan during the positive phase of CGT. The westward increasing low pressure anomalies with its north-south orientation provokes enormous north-south pressure gradient (lower pressure over land than over sea). This in turn enables the moist southerly flow from the Arabian Sea to penetrate farther northward over northwestern India and Pakistan. A monsoon trough like conditions develops over northwestern India and Pakistan where the moist southwesterly flow from the Arabian Sea and the Persian Gulf converge. The convergence in association with the orographic uplifting expedites convection and associated precipitation over northwestern India and Pakistan. The high resolution climate model ECHAM5 simulation also

  3. Evaluating the potential of concentrating solar power generation in Northwestern India

    International Nuclear Information System (INIS)

    Purohit, Ishan; Purohit, Pallav; Shekhar, Shashaank

    2013-01-01

    To accelerate the decarburization in the Indian power sector, concentrating solar power (CSP) needs to play an important role. CSP technologies have found significant space in the Jawaharlal Nehru National Solar Mission (JNNSM) of the Indian government in which 20,000 MW grid connected solar power projects have been targeted by 2022 with 50% capacity for CSP. In this study a preliminary attempt has been made to assess the potential of CSP generation in the Northwestern (NW) regions of India; which seems a high potential area as it has the highest annual solar radiation in India, favorable meteorological conditions for CSP and large amount of waste land. The potential of CSP systems in NW India is estimated on the basis of a detailed solar radiation and land resource assessment. The energy yield exercise has been carried out for the representative locations using System Advisor Model for four commercially available CSP technologies namely Parabolic Trough Collector (PTC), Central receiver system (CRS), Linear Fresnel Reflector (LFR) and Parabolic Dish System (PDS). The financial viability of CSP systems at different locations in NW India is also analyzed in this study. On the basis of a detailed solar radiation and land resource assessment, the maximum theoretical potential of CSP in NW India is estimated over 2000 GW taking into accounts the viability of different CSP technologies and land suitability criteria. The technical potential is estimated over 1700 GW at an annual direct normal incidence (DNI) over 1800 kW h/m 2 and finally, the economic potential is estimated over 700 GW at an annual DNI over 2000 kW h/m 2 in NW India. It is expected that in near future locations with lower DNI values could also become financially feasible with the development of new technologies, advancement of materials, economy of scale, manufacturing capability along with the enhanced policy measures etc. With an annual DNI over 1600 kW h/m 2 it is possible to exploit over 2000 GW CSP

  4. Aminostratigraphic correlations and paleotemperature implications, Pliocene-Pleistocene high-sea-level deposits, northwestern Alaska

    Science.gov (United States)

    Kaufman, Darrell S.; Brigham-Grette, Julie

    Multiple periods of Late Pliocene and Pleistocene high sea level are recorded by surficial deposits along the coastal plains of northwestern Alaska. Analyses of the extent of amino acid epimerization in fossil molluscan shells from the Nome coastal plain of the northern Bering Sea coast, and from the Alaskan Arctic Coastal Plain of the Chukchi and Beaufort Sea coasts, allow recognition of at least five intervals of higher-than-present relative sea level. Three Late Pliocene transgressions are represented at Nome by the complex and protracted Beringian transgression, and on the Arctic Coastal Plain by the Colvillian, Bigbendian, and Fishcreekian transgressions. These were followed by a lengthy period of non-marine deposition during the Early Pleistocene when sea level did not reach above its present position. A Middle Pleistocene high-sea-level event is represented at Nome by the Anvilian transgression, and on the Arctic Coastal Plain by the Wainwrightian transgression. Anvilian deposits at the type locality are considerably younger than previously thought, perhaps as young as Oxygen-Isotope Stage 11 (˜410,000 BP). Finally, the last interglacial Pelukian transgression is represented discontinuously along the shores of northwestern Alaska. Amino acid epimerization data, together with previous paleomagnetic measurements, radiometric-age determinations, and paleontologic evidence provide geochronological constraints on the sequence of marine deposits. They form the basis of regional correlations and offer a means of evaluating the post-depositional thermal history of the high-sea-level deposits. Provisional correlations between marine units at Nome and the Artic Coastal Plain indicate that the temperature difference that separates the two sites today had existed by about 3.0 Ma. Since that time, the effective diagenetic temperature was lowered by about 3-4°C at both sites, and the mean annual temperature was lowered considerably more. This temperature decrease was

  5. Report in the Energy and Intensity Frontiers, and Theoretical at Northwestern University

    Energy Technology Data Exchange (ETDEWEB)

    Velasco, Mayda [Northwestern Univ., Evanston, IL (United States); Schmitt, Michael [Northwestern Univ., Evanston, IL (United States); deGouvea, Andre [Northwestern Univ., Evanston, IL (United States); Low, Ian [Northwestern Univ., Evanston, IL (United States); Petriello, Frank [Northwestern Univ., Evanston, IL (United States); Schellman, Heidi [Northwestern Univ., Evanston, IL (United States)

    2016-03-31

    The Northwestern (NU) Particle Physics (PP) group involved in this report is active on all the following priority areas: Energy and Intensity Frontiers. The group is lead by 2 full profs. in experimental physics (Schmitt and Velasco), 3 full profs. in theoretical physics (de Gouvea, Low and Petriello), and Heidi Schellman who is now at Oregon State. Low and Petriello hold joint appointments with the HEP Division at Argonne National Laboratory. The theoretical PP research focuses on different aspects of PP phenomenology. de Gouvea dedicates a large fraction of his research efforts to understanding the origin of neutrino masses, neutrino properties and uncovering other new phenomena, and investigating connections between neutrino physics and other aspects of PP. Low works on Higgs physics as well as new theories beyond the Standard Model. Petriello pursues a research program in precision QCD and its associated collider phenomenology. The main goal of this effort is to improve the Standard Model predictions for important LHC observables in order to enable discoveries of new physics. In recent years, the emphasis on experimental PP at NU has been in collider physics. NU expands its efforts in new directions in both the Intensity and the Cosmic Frontiers (not discussed in this report). In the Intensity Frontier, Schmitt has started a new effort on Mu2e. He was accepted as a collaborator in April 2015 and is identified with important projects. In the Energy Frontier, Hahn, Schmitt and Velasco continue to have a significant impact and expanded their CMS program to include R&D for the real-time L1 tracking trigger and the high granularity calorimeter needed for the high-luminosity LHC. Hahn is supported by an independent DOE Career Award and his work will not be discussed in this document. The NU analysis effort includes searches for rare and forbidden decays of the Higgs bosons, Z boson, top quark, dark matter and other physics beyond the standard model topics. Four

  6. Recent exploration progresses on sandstone-hosted uranium deposits in north-western China

    International Nuclear Information System (INIS)

    Li, Z.

    2014-01-01

    The metallogenic target selection using multiple exploration techniques and drilling program for sandstone-hosted uranium deposits have been intensively carried out for recent years, and big progresses on new discoveries of uranium reserve/resource have been made in the Mesozoic sedimentary basins such as in Yili, Ordos etc. in North-western China The Yili basin is a depression one within the Tianshan Mountain belt in the western part of China. Its basement is composed of Proterozoic-Paleozoic metamorphic and sedimentary rocks, and covers of Mesozoic sediments. The early-middle Jurassic Shuixigou Group is major uranium-productive beds which are composed of three Formations such as Badaowan, Sangonghe, Xisanyao and eight sedimentary cycles. Uranium deposits are found in the south margin of the Basin and controlled by the redox zone. The combined exploration techniques of detailed sedimentary facies study, Rn-survey, high-precision magnetic and soil geochemical and seismic surveys have been successfully used to have locate the potential targets and mineralization zones. The enlargement of uranium reserve/resources in the known deposits and new resources in the selected new targets and cycles have been achieved through further drilling programs. The Ordos basin is a large Meso-Cenozoic basin developed in North China Platform, with its size of approximately 250,000 km"2 and is well known as an important “energy resources basin” because of abundance of coal, oil and gas deposits. The Dongsheng sandstone type uranium deposit is a large one discovered in recent years in northeastern Ordos basin. It is a special kind of sandstone type uranium deposit, different from other ordinary sandstone type deposits because of its unique signatures. It is generally controlled by a transitional zone between greenish and grayish sandstones, both of those two kinds of sandstones now indicate reduced geochemical environments. The greenish color of the paleooxidized sandstones mainly

  7. Field measurement of clear-sky solar irradiance in Badain Jaran Desert of Northwestern China

    International Nuclear Information System (INIS)

    Bi, Jianrong; Huang, Jianping; Fu, Qiang; Ge, Jinming; Shi, Jinsen; Zhou, Tian; Zhang, Wu

    2013-01-01

    The Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL) sponsored and conducted an intensive field campaign on dust aerosols in Badain Jaran Desert of Northwestern China from April 20 to June 20, 2010. A set of state-of-the-art broadband radiometers and sun/sky photometers were deployed along with launched radiosonde. In this paper, we compared the simulated solar irradiances by using the SBDART radiative transfer model with those from the ground-based measurements for 69 selected cases of 7 days. It was shown that the averaged aerosol optical depth at 500 nm (AOD 500 ) is 0.18±0.09 with AOD 500 less than 0.5 for all cases. The single-scattering albedo and asymmetry factor at 675 nm are 0.928±0.035, 0.712±0.023, respectively. The AODs retrieved from the CIMEL sun photometer at various wavelengths agree well with those from the PREDE sky radiometer, and the columnar water vapor contents from CIMEL also agree well with radiosonde observations. In the radiative closure experiment, we used a collocated thermopile pyrgeometer with a shadow and ventilator to correct the thermal dome offset of diffuse irradiance measurement. The mean differences between model and measurements are −9.1 Wm −2 (−2.6%) for the direct irradiance, +3.1 Wm −2 (+2.8%) for diffuse irradiance, and −6.0 Wm −2 (−1.3%) for global irradiance, which indicates an excellent radiative closure. Aerosol shortwave direct radiative forcing (ARF) and radiative heating rate are also investigated. The daily mean ARF ranges from −4.8 to +0.4 Wm −2 at the top of the atmosphere, −5.2 to −15.6 Wm −2 at the surface, and 5.2 to 10.8 Wm −2 in the atmosphere. The corresponding radiative heating rates for the whole atmosphere due to dust aerosols are 0.07, 0.11, 0.14, 0.11, 0.10, 0.08, and 0.07 K/day for the 7 selected cloudless days. These solar radiative forcing can be considered as the representative impact of background dust aerosol in Northwestern China

  8. Mycobacterium tuberculosis population in northwestern Russia: an update from Russian-EU/Latvian border region.

    Directory of Open Access Journals (Sweden)

    Igor Mokrousov

    Full Text Available This study aimed to characterize the population structure of Mycobacterium tuberculosis in Pskov oblast in northwestern Russia, to view it in the geographical context, to compare drug resistance properties across major genetic families. Ninety M. tuberculosis strains from tuberculosis (TB patients, permanent residents in Pskov oblast were subjected to LAM-specific IS6110-PCR and spoligotyping, followed by comparison with SITVITWEB and MIRU-VNTRplus databases. The Beijing genotype (n = 40 was found the most prevalent followed by LAM (n = 18, T (n = 13, Haarlem (n = 10, Ural (n = 5, and Manu2 (n = 1; the family status remained unknown for 3 isolates. The high rate of Beijing genotype and prevalence of LAM family are similar to those in the other Russian settings. A feature specific for M. tuberculosis population in Pskov is a relatively higher rate of Haarlem and T types. Beijing strains were further typed with 12-MIRU (followed by comparison with proprietary global database and 3 hypervariable loci QUB-3232, VNTR-3820, VNTR-4120. The 12-MIRU typing differentiated 40 Beijing strains into 14 types (HGI = 0.82 while two largest types were M2 (223325153533 prevalent throughout former USSR and M11 (223325173533 prevalent in Russia and East Asia. The use of 3 hypervariable loci increased a discrimination of the Beijing strains (18 profiles, HGI = 0.89. Both major families Beijing and LAM had similar rate of MDR strains (62.5 and 55.6%, respectively that was significantly higher than in other strains (21.9%; P = 0.001 and 0.03, respectively. The rpoB531 mutations were more frequently found in Beijing strains while LAM drug resistant strains mainly harbored rpoB516 and inhA -15 mutations. Taken together with a high rate of multidrug resistance among Beijing strains from new TB cases (79.3% versus 44.4% in LAM, these findings suggest the critical impact of the Beijing genotype on the current situation with MDR-TB in the

  9. Modern wildlife conservation initiatives and the pastoralist/hunter nomads of northwestern Tibet

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    Joseph L. Fox

    2004-04-01

    Full Text Available In 1993 the Tibet Autonomous Region (TAR of China established the 300 000 km2 Chang Tang Nature Preserve on the northwestern Tibetan plateau, an action precipitated by rapidly diminishing populations of chiru (Tibetan antelope and wild yak. Some 30 000 nomadic pastoralists use areas within this reserve for livestock grazing, with many having traditionally depended in part on hunting for supplementary subsistence and trade. Following a 1997 request from TAR leaders for international assistance in addressing the conservation issues associated with the creation of this reserve, the TAR Forestry Bureau and the Network for University Co-operation Tibet — Norway began a 3-year research collaboration program in 2000 to outline human-wildlife interactions and conservation priorities in the western part of the reserve. To date, four excursions (2-6 weeks each have been made to the western Chang Tang region, and investigations of interactions between pastoralists and wildlife conservation objectives have been initiated in an area of about 5000 km2, including the 2300 km2 Aru basin located at 5000 m elevation at the northern edge of pastoralist inhabitation. The Aru site is unique in that nomads have only recently returned to this previously off-limits basin. But, as in surrounding areas, the people's lives are undergoing changes recently influenced by the introduction of permanent winter houses, changing international trade in shahtoosh and cashmere wool, and a move towards stricter hunting regulations. The northwestern Chang Tang, with the Aru basin as a prime site, represents one of the last strongholds of the endangered chiru and wild yak, as well as home to Tibetan gazelle, kiang, Tibetan argali, blue sheep, wolf, snow leopard and brown bear. In autumn 2000, for example, with approximately 12 000 of the wild ungulates (mostly the migratory chiru within the Aru basin along with some 8000 domestic livestock, issues of land use overlap and possible

  10. Assessment of chlorophyll variability along the northwestern coast of Iberian Peninsula

    Science.gov (United States)

    Picado, A.; Alvarez, I.; Vaz, N.; Varela, R.; Gomez-Gesteira, M.; Dias, J. M.

    2014-10-01

    The northwestern coast of the Iberian Peninsula is characterized by a high primary production mainly supported by coastal upwelling, creating an extraordinary commercial interest for fisheries and aquaculture. Considering chlorophyll-a (Chl-a) as an indicator of primary production, its spatio-temporal variability was researched in this study in the surface water of this upwelling region from 1998 to 2007. Satellite derived Chl-a, Sea Surface Temperature (SST) and Ekman transport data as well as the inflow of the main rivers discharging into the study area were used to investigate the origin of the Chl-a concentration. Empirical Orthogonal Function (EOF) analysis of weekly Chl-a images was performed, as well as correlation analysis between Chl-a concentration, Ekman transport and river discharge. EOF results suggest that the highest Chl-a concentration occurs near the coast up to 60 km offshore. The interannual variability of Chl-a, SST and Ekman transport was also studied considering summer and winter months. Generally, 2005, 2006 and 2007 were the most productive years during the summer months with high Chl-a concentrations along the coast associated to the strong upwelling conditions observed. Otherwise, 1998 seemed to be the most productive year during winter. The absence of upwelling favorable conditions together with localized low SST and considerable discharges, suggests that the high Chl-a concentrations observed during this period are mainly due to the entrance of nutrients through river runoff. However, in winter, high concentrations of colored dissolved organic matter (CDOM), associated with river runoff, are present in the ocean surface, leading to an erroneous strong signal of the satellite. During winter correlations of 0.58 and 0.49 were found between Chl-a concentration and Douro and Minho discharges, respectively, evidencing that high Chl-a concentration was related with river runoff. Otherwise, during summer, Chl-a and Ekman transport exhibited a

  11. Geomorphological and sedimentary processes of the glacially influenced northwestern Iberian continental margin and abyssal plains

    Science.gov (United States)

    Llave, Estefanía; Jané, Gloria; Maestro, Adolfo; López-Martínez, Jerónimo; Hernández-Molina, F. Javier; Mink, Sandra

    2018-07-01

    The offshore region of northwestern Iberia offers an opportunity to study the impacts of along-slope processes on the morphology of a glacially influenced continental margin, which has traditionally been conceptually characterised by predominant down-slope sedimentary processes. High-resolution multibeam bathymetry, acoustic backscatter and ultrahigh-resolution seismic reflection profile data are integrated and analysed to describe the present-day and recent geomorphological features and to interpret their associated sedimentary processes. Seventeen large-scale seafloor morphologies and sixteen individual echo types, interpreted as structural features (escarpments, marginal platforms and related fluid escape structures) and depositional and erosional bedforms developed either by the influence of bottom currents (moats, abraded surfaces, sediment waves, contourite drifts and ridges) or by gravitational features (gullies, canyons, slides, channel-levee complexes and submarine fans), are identified for the first time in the study area (spanning 90,000 km2 and water depths of 300 m to 5 km). Different types of slope failures and turbidity currents are mainly observed on the upper and lower slopes and along submarine canyons and deep-sea channels. The middle slope morphologies are mostly determined by the actions of bottom currents (North Atlantic Central Water, Mediterranean Outflow Water, Labrador Sea Water and North Atlantic Deep Water), which thereby define the margin morphologies and favour the reworking and deposition of sediments. The abyssal plains (Biscay and Iberian) are characterised by pelagic deposits and channel-lobe systems (the Cantabrian and Charcot), although several contourite features are also observed at the foot of the slope due to the influence of the deepest water masses (i.e., the North Atlantic Deep Water and Lower Deep Water). This work shows that the study area is the result of Mesozoic to present-day tectonics (e.g. the marginal platforms

  12. Trends and causes of severity, size, and number of fires in northwestern California, USA.

    Science.gov (United States)

    Miller, J D; Skinner, C N; Safford, H D; Knapp, E E; Ramirez, C M

    2012-01-01

    Research in the last several years has indicated that fire size and frequency are on the rise in western U.S. forests. Although fire size and frequency are important, they do not necessarily scale with ecosystem effects of fire, as different ecosystems have different ecological and evolutionary relationships with fire. Our study assessed trends and patterns in fire size and frequency from 1910 to 2008 (all fires > 40 ha), and the percentage of high-severity in fires from 1987 to 2008 (all fires > 400 ha) on the four national forests of northwestern California. During 1910-2008, mean and maximum fire size and total annual area burned increased, but we found no temporal trend in the percentage of high-severity fire during 1987-2008. The time series of severity data was strongly influenced by four years with region-wide lightning events that burned huge areas at primarily low-moderate severity. Regional fire rotation reached a high of 974 years in 1984 and fell to 95 years by 2008. The percentage of high-severity fire in conifer-dominated forests was generally higher in areas dominated by smaller-diameter trees than in areas with larger-diameter trees. For Douglas-fir forests, the percentage of high-severity fire did not differ significantly between areas that re-burned and areas that only burned once (10% vs. 9%) when re-burned within 30 years. Percentage of high-severity fire decreased to 5% when intervals between first and second fires were > 30 years. In contrast, in both mixed-conifer and fir/high-elevation conifer forests, the percentage of high-severity fire was less when re-burned within 30 years compared to first-time burned (12% vs. 16% for mixed conifer; 11% vs. 19% for fir/high-elevation conifer). Additionally, the percentage of high-severity fire did not differ whether the re-burn interval was less than or greater than 30 years. Years with larger fires and greatest area burned were produced by region-wide lightning events, and characterized by less winter

  13. Fertile lithospheric mantle beneath the northwestern North China and its implication for the subduction of the Paleo-Asian Ocean

    Science.gov (United States)

    Dai, H. K.; Zheng, J.; Su, Y. P.; Xiong, Q.; Pan, S. K.

    2017-12-01

    The nature of the sub-continental lithospheric mantle (SCLM) beneath the western North China Craton (NCC) is poorly known, which hinders understanding the cratonic response to the southward subduction of the Paleo-Asian Ocean. Mineral chemical data of spinel lherzolite xenoliths from newly discovered Cenozoic Langshan basalts in the northwestern part of the craton have been integrated with data from other localities across the western NCC, to put constrains on the SCLM nature and to explore the reworking processes involved. Compositions of mineral cores (i.e., Mg# in olivine = 88 91) and P-T estimates ( 1.2 GPa, 950 oC) suggest the Langshan xenoliths/xenocrysts represent fragments of the uppermost SCLM and experienced ancient continental crust, and 2) the sharp decrease in lithospheric thickness from the inner part to the northern margin of the western NCC, the SCLM beneath the northwestern part should have been strongly rejuvenated or replaced by fertile and non-cratonic mantle. Combined with other geological evidence on the northwestern margin, the mantle replacement and metasomatism were likely triggered by southward subduction of the Paleo-Asian Ocean.

  14. Lost Terranes of Zealandia: possible development of late Paleozoic and early Mesozoic sedimentary basins at the southwest Pacific margin of Gondwanaland, and their destination as terranes in southern South America Terrenos perdidos de Zealandia: posible desarrollo de cuencas sedimentarias del Paleozoico tardío y Mesozoico temprano en el margen suroccidental del Pacífico de Gondwana y su destino como terrenos en el sur de América del Sur

    Directory of Open Access Journals (Sweden)

    Christopher J Adams

    2010-07-01

    Full Text Available Latest Precambrian to Ordovician metasedimentary successions and Cambrian-Ordovician and Devonian-Carboniferous granitoids form the major part of the basement of southern Zealandia and adjacent sectors of Antarctica and southeast Australia. Uplift/cooling ages of these rocks, and local Devonian shallow-water cover sequences suggest that final consolidation of the basement occurred through Late Paleozoic time. A necessary consequence of this process would have been contemporaneous erosion and the substantial development of marine sedimentary basins at the Pacific margin of Zealandia. These are found nowhere at the present day, suggesting that the basins have been lost by tectonic erosion, perhaps in a margin-parallel dextral translation similar to late Paleozoic-Mesozoic suspect terranes of New Zealand. Aprobable detrital zircon age pattern is assembled for these lost Zealandia sediments, and then compared with those of pre-Jurassic (probable Triassic to Devonian metasedimentary rocks in the Chilean archipelago. Significant Mesoproterozoic, latest Neoproterozoic-Cambrian and Devonian-Carboniferous detrital zircon age components are common to both, thus supporting a possible Chilean terrane destination for these 'lost terranes of Zealandia'.Las sucesiones metasedimentarias del Precámbrico tardío al Ordovícico y granitoides del Cámbrico-Ordovícico y Devónico-Carbonífero constituyen la mayor parte del basamento del sur de Zealandia y sectores adyacentes de la Antartica y el sudeste de Australia. Las edades de enfriamiento/alzamiento de estas rocas y la cobertura local de secuencias de aguas someras del Devónico, sugieren que la consolidación definitiva del basamento se produjo durante el Paleozoico tardío. Una consecuencia necesaria de este proceso habría sido la erosion contemporánea y el desarrollo sustancial de cuencas sedimentarias marinas en el margen del Pacífico de Zealandia. Estas no se encuentran en ninguna parte en la

  15. Understanding north-western Mediterranean climate variability: a multi-proxy and multi-sequence approach based on wavelet analysis.

    Science.gov (United States)

    Azuara, Julien; Lebreton, Vincent; Jalali, Bassem; Sicre, Marie-Alexandrine; Sabatier, Pierre; Dezileau, Laurent; Peyron, Odile; Frigola, Jaime; Combourieu-Nebout, Nathalie

    2017-04-01

    Forcings and physical mechanisms underlying Holocene climate variability still remain poorly understood. Comparison of different paleoclimatic reconstructions using spectral analysis allows to investigate their common periodicities and helps to understand the causes of past climate changes. Wavelet analysis applied on several proxy time series from the Atlantic domain already revealed the first key-issues on the origin of Holocene climate variability. However the differences in duration, resolution and variance between the time-series are important issues for comparing paleoclimatic sequences in the frequency domain. This work compiles 7 paleoclimatic proxy records from 4 time-series from the north-western Mediterranean all ranging from 7000 to 1000 yrs cal BP: -pollen and clay mineral contents from the lagoonal sediment core PB06 recovered in southern France, -Sea Surface Temperatures (SST) derived from alkenones, concentration of terrestrial alkanes and their average chain length (ACL) from core KSGC-31_GolHo-1B recovered in the Gulf of Lion inner-shelf, - δ18O record from speleothems recovered in the Asiul Cave in north-western Spain, -grain size record from the deep basin sediment drift core MD99-2343 north of Minorca island. A comparison of their frequency content is proposed using wavelet analysis and cluster analysis of wavelet power spectra. Common cyclicities are assessed using cross-wavelet analysis. In addition, a new algorithm is used in order to propagate the age model errors within wavelet power spectra. Results are consistents with a non-stationnary Holocene climate variability. The Halstatt cycles (2000-2500 years) depicted in many proxies (ACL, errestrial alkanes and SSTs) demonstrate solar activity influence in the north-western Mediterranean climate. Cluster analysis shows that pollen and ACL proxies, both indicating changes in aridity, are clearly distinct from other proxies and share significant common periodicities around 1000 and 600 years

  16. Enhancement of the aerosol direct radiative effect by semi-volatile aerosol components: airborne measurements in North-Western Europe

    Directory of Open Access Journals (Sweden)

    W. T. Morgan

    2010-09-01

    Full Text Available A case study of atmospheric aerosol measurements exploring the impact of the vertical distribution of aerosol chemical composition upon the radiative budget in North-Western Europe is presented. Sub-micron aerosol chemical composition was measured by an Aerodyne Aerosol Mass Spectrometer (AMS on both an airborne platform and a ground-based site at Cabauw in the Netherlands. The examined period in May 2008 was characterised by enhanced pollution loadings in North-Western Europe and was dominated by ammonium nitrate and Organic Matter (OM. Both ammonium nitrate and OM were observed to increase with altitude in the atmospheric boundary layer. This is primarily attributed to partitioning of semi-volatile gas phase species to the particle phase at reduced temperature and enhanced relative humidity. Increased ammonium nitrate concentrations in particular were found to strongly increase the ambient scattering potential of the aerosol burden, which was a consequence of the large amount of associated water as well as the enhanced mass. During particularly polluted conditions, increases in aerosol optical depth of 50–100% were estimated to occur due to the observed increase in secondary aerosol mass and associated water uptake. Furthermore, the single scattering albedo was also shown to increase with height in the boundary layer. These enhancements combined to increase the negative direct aerosol radiative forcing by close to a factor of two at the median percentile level. Such increases have major ramifications for regional climate predictions as semi-volatile components are often not included in aerosol models.

    The results presented here provide an ideal opportunity to test regional and global representations of both the aerosol vertical distribution and subsequent impacts in North-Western Europe. North-Western Europe can be viewed as an analogue for the possible future air quality over other polluted regions of the Northern Hemisphere, where

  17. Breeding biology of passerines in a subtropical montane forest in northwestern Argentina

    Science.gov (United States)

    Auer, S.K.; Bassar, R.D.; Fontaine, J.J.; Martin, T.E.

    2007-01-01

    The breeding ecology of south temperate bird species is less widely known than that of north temperate species, yet because they comprise a large portion of the world's avian diversity, knowledge of their breeding ecology can contribute to a more comprehensive understanding of the geographic diversity of avian reproductive traits and life history strategies. We provide the first detailed examination of the reproductive strategies of 18 forest passerines of subtropical, northwestern Argentina. Mean clutch sizes were smaller and egg mass was greater than for north temperate birds, but differed among species and nest types, with cavity-nesters having larger clutches than species with open-cup and enclosed nests. Across all species, the average breeding season duration was 50 days; thus, the common perception that southern species have smaller clutch sizes because of longer breeding seasons is not supported in this community. Daily nest predation rates were influenced by nest type, cavity nests suffering the least from predation, as found in north temperate systems. Only females incubated eggs in all but one species, whereas both parents fed and cared for nestlings in all species. Mean nest attentiveness was low compared to north temperate passerines. Mean hourly nestling feeding rates differed among species and were negatively related to nest predation risk. In short, coexisting species in this subtropical forest varied in their life history strategies, in part correlated with variation in nest predation risk, but also differing from north temperate species. ?? The Cooper Ornithological Society 2007.

  18. Geochemical and geochronological constrains on the Chiang Khong volcanic rocks (northwestern Thailand) and its tectonic implications

    Science.gov (United States)

    Qian, Xin; Feng, Qinglai; Chonglakmani, Chongpan; Monjai, Denchok

    2013-12-01

    Volcanic rocks in northwestern Thailand exposed dominantly in the Chiang Khong area, are commonly considered to be genetically linked to the tectonic evolution of the Paleo-Tethyan Ocean. The volcanic rocks consist mainly of andesitic to rhyolitic rocks and are traditionally mapped as Permian-Triassic sequences. Our zircon U-Pb geochronological results show that two andesitic samples (TL-1-B and TL-31-B), are representative of the Doi Yao volcanic zone, and give a mean weighted age of 241.2±4.6 Ma and 241.7±2.9 Ma, respectively. The rhyolitic sample (TL-32-B1) from the Doi Khun Ta Khuan volcanic zone erupted at 238.3±3.8 Ma. Such ages indicate that Chiang Khong volcanic rocks erputed during the early Middle Triassic period. Seven samples from the Doi Yao and Doi Khun Ta Khuan zones exhibit an affinity to arc volcanics. Three rhyolitic samples from the Chiang Khong area have a geochemical affinity to both arc and syn-collisional volcanic rocks. The Chiang Khong arc volcanic rocks can be geochemically compared with those in the Lampang area in northern Thailand, also consistent with those in Jinghong area of southwestern Yunnan. This indicates that the Chiang Rai arc-volcanic zone might northwardly link to the Lancangjiang volcanic zone in southwestern China.

  19. Previously Unrecognized Ornithuromorph Bird Diversity in the Early Cretaceous Changma Basin, Gansu Province, Northwestern China

    Science.gov (United States)

    Wang, Ya-Ming; O'Connor, Jingmai K.; Li, Da-Qing; You, Hai-Lu

    2013-01-01

    Here we report on three new species of ornithuromorph birds from the Lower Cretaceous Xiagou Formation in the Changma Basin of Gansu Province, northwestern China: Yumenornis huangi gen. et sp. nov., Changmaornis houi gen. et sp. nov., and Jiuquanornis niui gen. et sp. nov.. The last of these is based on a previously published but unnamed specimen: GSGM-05-CM-021. Although incomplete, the specimens can be clearly distinguished from each other and from Gansus yumenensis Hou and Liu, 1984. Phylogenetic analysis resolves the three new taxa as basal ornithuromorphs. This study reveals previously unrecognized ornithuromorph diversity in the Changma avifauna, which is largely dominated by Gansus but with at least three other ornithuromorphs. Body mass estimates demonstrate that enantiornithines were much smaller than ornithuromorphs in the Changma avifauna. In addition, Changma enantiornithines preserve long and recurved pedal unguals, suggesting an arboreal lifestyle; in contrast, Changma ornithuromorphs tend to show terrestrial or even aquatic adaptions. Similar differences in body mass and ecology are also observed in the Jehol avifauna in northeastern China, suggesting niche partitioning between these two clades developed early in their evolutionary history. PMID:24147058

  20. Toothed whales in the northwestern Mediterranean: Insight into their feeding ecology using chemical tracers

    International Nuclear Information System (INIS)

    Praca, Emilie; Laran, Sophie; Lepoint, Gilles; Thome, Jean-Pierre; Quetglas, Antoni; Belcari, Paola; Sartor, Paolo; Dhermain, Frank; Ody, Denis; Tapie, Nathalie

    2011-01-01

    Research highlights: →δ 15 N highlights significant different trophic levels. → Similar δ 13 C indicate a habitat superposition or corroborate seasonal migrations. → Congener 180 and tDDT/tPCB show wider migrations for sperm whales. - Abstract: Risso's dolphins, pilot whales and sperm whales rarely strand in the northwestern Mediterranean. Thus, their feeding ecology, through the analysis of stomach contents, is poorly known. The aim of this study was to gain further insight into the segregation/superposition of the diet and habitat of Risso's dolphins, pilot whales and sperm whales using chemical tracers, namely, stable isotopes (δ 13 C, δ 15 N) and organochlorines. Significantly different δ 15 N values were obtained in Risso's dolphins (11.7 ± 0.7 per mille ), sperm whales (10.8 ± 0.3 per mille ) and pilot whales (9.8 ± 0.3 per mille ), revealing different trophic levels. These differences are presumably due to various proportions of Histioteuthidae cephalopods in each toothed whale's diet. Similar δ 13 C contents between species indicated long-term habitat superposition or corroborated important seasonal migrations. Lower congener 180 concentrations (8.20 vs. 21.73 μg.g -1 lw) and higher tDDT/tPCB ratios (0.93 vs. 0.42) were observed in sperm whales compared with Risso's dolphins and may indicate wider migrations for the former. Therefore, competition between these species seems to depend on different trophic levels and migration patterns.

  1. Effects of Age and Size on Xylem Phenology in Two Conifers of Northwestern China

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    Qiao Zeng

    2018-01-01

    Full Text Available The climatic signals that directly affect the trees can be registered by xylem during its growth. If the timings and duration of xylem formation change, xylogenesis can occur under different environmental conditions and subsequently be subject to different climatic signals. An experimental design was applied in the field to disentangle the effects of age and size on xylem phenology, and it challenges the hypothesis that the timings and dynamics of xylem growth are size-dependent. Intra-annual dynamics of xylem formation were monitored weekly during the growing seasons 2013 and 2014 in Chinese pine (Pinus tabulaeformis and Qilian juniper (Juniperus przewalskii with different sizes and ages in a semi-arid region of northwestern China. Cell differentiation started 3 weeks earlier in 2013 and terminated 1 week later in 2014 in small-young pines than in big-old pines. However, differences in the timings of growth reactivation disappeared when comparing the junipers with different sizes but similar age. Overall, 77 days were required for xylem differentiation to take place, but timings were shorter for older trees, which also exhibited smaller cell production. Results from this study suggest that tree age does play an important role in timings and duration of growth. The effect of age should also be considered to perform reliable responses of trees to climate.

  2. Effects of Age and Size on Xylem Phenology in Two Conifers of Northwestern China.

    Science.gov (United States)

    Zeng, Qiao; Rossi, Sergio; Yang, Bao

    2017-01-01

    The climatic signals that directly affect the trees can be registered by xylem during its growth. If the timings and duration of xylem formation change, xylogenesis can occur under different environmental conditions and subsequently be subject to different climatic signals. An experimental design was applied in the field to disentangle the effects of age and size on xylem phenology, and it challenges the hypothesis that the timings and dynamics of xylem growth are size-dependent. Intra-annual dynamics of xylem formation were monitored weekly during the growing seasons 2013 and 2014 in Chinese pine ( Pinus tabulaeformis ) and Qilian juniper ( Juniperus przewalskii ) with different sizes and ages in a semi-arid region of northwestern China. Cell differentiation started 3 weeks earlier in 2013 and terminated 1 week later in 2014 in small-young pines than in big-old pines. However, differences in the timings of growth reactivation disappeared when comparing the junipers with different sizes but similar age. Overall, 77 days were required for xylem differentiation to take place, but timings were shorter for older trees, which also exhibited smaller cell production. Results from this study suggest that tree age does play an important role in timings and duration of growth. The effect of age should also be considered to perform reliable responses of trees to climate.

  3. Dwarfism and feeding behaviours in Oligo–Miocene crocodiles from Riversleigh, northwestern Queensland, Australia

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    Michael Stein

    2016-02-01

    Full Text Available Instances of dwarfism in the fossil record are of interest to palaeontologists because they often provide insight into aspects of palaeoecology. Fossil species of Australian-Pacific mekosuchine genus Mekosuchus have been described as dwarf, primarily terrestrial crocodiles, in contrast with the nearly ubiquitous semi-aquatic habitus of extant crocodilians (Willis 1997. This hypothesis has been difficult to test because of limited knowledge of the cranial and postcranial skeleton of extinct taxa and the continuous nature of crocodilian growth. New crocodilian vertebral material from Riversleigh, northwestern Queensland, tentatively referred to Mekosuchus whitehunterensis Willis, 1997, displays morphological maturity indicative of adult snout-vent length little over a half-meter, proportionally smaller than extant dwarf taxa. Further, this material displays morphology that indicates a relatively large epaxial neck musculature for its body-size. These attributes suggest this dwarf mekosuchine employed unusual feeding behaviours. The ability to perform normal death-roll, de-fleshing behaviours would be limited in a mekosuchine of such small size. Given the powerful neck muscles and other anatomical features, it is more likely that this mekosuchine killed and/or dismembered its prey using a relatively forceful lifting and shaking of the head.

  4. Genetic diversity of a late prehispanic group of the Quebrada de Humahuaca, northwestern Argentina.

    Science.gov (United States)

    Mendisco, Fanny; Keyser, Christine; Seldes, Veronica; Rivolta, Clara; Mercolli, Pablo; Cruz, Pablo; Nielsen, Axel E; Crubezy, Eric; Ludes, Bertrand

    2014-09-01

    This palaeogenetic study focused on the analysis of a late prehispanic Argentinean group from the Humahuaca valley, with the main aim of reconstructing its (micro)evolutionary history. The Humahuaca valley, a natural passageway from the eastern plains to the highlands, was the living environment of Andean societies whose cultural but especially biological diversity is still poorly understood. We analyzed the DNA extracted from 39 individuals who populated this upper valley during the Regional Development period (RDP) (between the 11th and 15th centuries CE), to determine their maternal and paternal genetic ancestry. Some mitochondrial and Y-chromosomal haplotypes specific to the Andean region are consistent with an origin in the highlands of Central Andes. On the other hand, a significant genetic affinity with contemporary admixed communities of the Chaco area was detected. Expectedly, recent demographic events, such as the expansion of the Inca Empire or the European colonization, have changed the original mitochondrial gene pool of the ancient Humahuaca Valley community. Finally, we identified a particular geographical organization of the prehispanic populations of Northwestern Argentina. Our results suggest that the communities of the region were divided between two different spheres of interaction, which is consistent with assumptions made by means of craniometric traits. © 2014 John Wiley & Sons Ltd/University College London.

  5. Children's education and home electrification: A case study in northwestern Madagascar

    International Nuclear Information System (INIS)

    Rajaona Daka, Karen; Ballet, Jerome

    2011-01-01

    Assessments of the impact of electrification on the quality of life of households in developing countries have increased over the last decade. One aspect that has still received little attention is education and the ability of children to keep up at school. The underlying hypothesis is that electrification enables children to do their homework in the evening and so keep up with their school work. To this first hypothesis we add a second one, concerning the relation between access to electricity and attendance to school according to gender. Although most household tasks are carried out by the mothers, their daughters are also involved, and electrification could have a beneficial effect by making easier for girls to do their homework in the evening and easier for the mothers to help them. We will check the validity of these hypotheses using a case study of 162 children attending school in a small town in northwestern Madagascar. - Research Highlights: → We use a sample of 162 children in Madagascar to test the effect of access to the electricity supply in home to the education of children. → We also test the effect to the electricity supply in home to gender-specificities. → Our results confirm that electrification can contribute to reduce social reproduction with regard to education. → Our results also show that electrification helps to reduce gender inequalities.

  6. Bluetongue disease and seroprevalence in South American camelids from the northwestern region of the United States.

    Science.gov (United States)

    Allen, Andrew J; Stanton, James B; Evermann, James F; Fry, Lindsay M; Ackerman, Melissa G; Barrington, George M

    2015-03-01

    In late summer/early fall of 2013, 2 South American camelids from central Washington were diagnosed with fatal bluetongue viral disease, an event which is rarely reported. A 9-year-old intact male llama (Lama glama), with a 1-day history of anorexia, recumbency, and dyspnea before death. Abundant foam discharged from the mouth and nostrils, and the lungs were severely edematous on postmortem examination. Histologically, there was abundant intra-alveolar edema with fibrin. Hemorrhage and edema disrupted several other organs. Bluetongue viral RNA was detected by reverse transcription polymerase chain reaction (RT-PCR), and serotype 11 was identified by sequencing a segment of the VP2 outer capsid gene. Approximately 1 month later, at a site 150 miles north of the index case, a 2-year-old female alpaca with similar, acutely progressive clinical signs was reported. A postmortem examination was performed, and histologic lesions from the alpaca were similar to those of the llama, and again serotype 11 was detected by PCR. The occurrence of bluetongue viral infection and disease is described in the context of seasonal Bluetongue virus activity within the northwestern United States and southwestern Canada. © 2015 The Author(s).

  7. Spatial dynamics of Fabiana imbricata shrublands in northwestern Patagonia in relation to natural fires

    Directory of Open Access Journals (Sweden)

    L. Ghermandi

    2010-05-01

    Full Text Available Fire is a critical disturbance in the structuring and functioning of most Mediterranean ecosystems. In northwestern Patagonia, vegetation patterns are strongly influenced by fire and environmental heterogeneity. Dendroecology, together with satellite imagery and GIS, have been demonstrated to be useful tools in studies that relate to fire effects with patches, patterns and species dynamics at landscape scale. Such studies can be approached from landscape ecology, which has evolved in the last years supported by the development of remote sensing and GIS technologies. This study evaluates the spatial dynamic of F. imbricata in response to fire using remote sensing, GIS and dendrochronology techniques, at landscape scale. Two sites were evaluated and one of them was affected by fire in the year 1999. The digital processing images (using the NBR spectral index and the dendroecological analysis verified this. A fire, occurring in 1978, was also detected by the analysis of F. imbricata growth rings. The relation between F. imbricata shrubland dynamics and spatial configuration with fire, land topography and hydrography was established in the study area.

  8. Temporal Behavior of Lake Size-Distribution in a Thawing Permafrost Landscape in Northwestern Siberia

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    Johanna Mård Karlsson

    2014-01-01

    Full Text Available Arctic warming alters regional hydrological systems, as permafrost thaw increases active layer thickness and in turn alters the pathways of water flow through the landscape. Further, permafrost thaw may change the connectivity between deeper and shallower groundwater and surface water altering the terrestrial water balance and distribution. Thermokarst lakes and wetlands in the Arctic offer a window into such changes as these landscape elements depend on permafrost and are some of the most dynamic and widespread features in Arctic lowland regions. In this study we used Landsat remotely sensed imagery to investigate potential shifts in thermokarst lake size-distributions, which may be brought about by permafrost thaw, over three distinct time periods (1973, 1987–1988, and 2007–2009 in three hydrological basins in northwestern Siberia. Results revealed fluctuations in total area and number of lakes over time, with both appearing and disappearing lakes alongside stable lakes. On the whole basin scales, there is no indication of any sustained long-term change in thermokarst lake area or lake size abundance over time. This statistical temporal consistency indicates that spatially variable change effects on local permafrost conditions have driven the individual lake changes that have indeed occurred over time. The results highlight the importance of using multi-temporal remote sensing data that can reveal complex spatiotemporal variations distinguishing fluctuations from sustained change trends, for accurate interpretation of thermokarst lake changes and their possible drivers in periods of climate and permafrost change.

  9. Modeling Woody Biomass Procurement for Bioenergy Production at the Atikokan Generating Station in Northwestern Ontario, Canada

    Directory of Open Access Journals (Sweden)

    Thakur Upadhyay

    2012-12-01

    Full Text Available Efficient procurement and utilization of woody biomass for bioenergy production requires a good understanding of biomass supply chains. In this paper, a dynamic optimization model has been developed and applied to estimate monthly supply and procurement costs of woody biomass required for the Atikokan Generating Station (AGS in northwestern Ontario, based on its monthly electricity production schedule. The decision variables in the model are monthly harvest levels of two types of woody biomass, forest harvest residues and unutilized biomass, from 19,315 forest depletion cells (each 1 km2 for a one year planning horizon. Sixteen scenarios are tested to examine the sensitivity of the cost minimization model to changing economic and technological parameters. Reduction in moisture content and improvement of conversion efficiency showed relatively higher reductions in monthly and total costs of woody biomass feedstock for the AGS. The results of this study help in understanding and designing decision support systems for optimal biomass supply chains under dynamic operational frameworks.

  10. Geodiversity action plans for the enhancement of geoheritage in the Piemonte region (north-western Italy

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    Elena Ferrero

    2012-07-01

    Full Text Available A geoethical approach to geodiversity allows better understanding of the value of abiotic nature and enhances its conservation and development. Our basic assumption is that even during an economical crisis, geoheritage sites can serve both public and private interests. A set of nine strategic geothematic areas were chosen to represent the geodiversity of the Piemonte region, north-western Italy, each of which is characterized by great potential for scientific studies, enhancement of public understanding of science, recreational activities, and economic support to the local communities. Specialized research teams individuated critical aspects to advance our knowledge of the geological history of the Piemonte region, through climate and environmental changes, natural hazards, soil processes, and georesources. The scientific concepts and techniques were coupled with geodiffusion actions and products: not only geosites, but also museum collections, evidence of mining and quarrying activities, science exhibitions, and nature trails. The preliminary results have allowed action plans to be developed with local partners, to assess the geoheritage management requirements. A series of investigations were carried out to improve the visual representation of the geological processes and the evolutionary scenarios. Further outcomes of the project will include didactic tools for educators, schools, and the public in general.

  11. Bootstrap inversion for Pn wave velocity in North-Western Italy

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    C. Eva

    1997-06-01

    Full Text Available An inversion of Pn arrival times from regional distance earthquakes (180-800 km, recorded by 94 seismic stations operating in North-Western Italy and surrounding areas, was carried out to image lateral variations of P-wave velocity at the crust-mantle boundary, and to estimate the static delay time at each station. The reliability of the obtained results was assessed using both synthetic tests and the bootstrap Monte Carlo resampling technique. Numerical simulations demonstrated the existence of a trade-off between cell velocities and estimated station delay times along the edge of the model. Bootstrap inversions were carried out to determine the standard deviation of velocities and time terms. Low Pn velocity anomalies are detected beneath the outer side of the Alps (-6% and the Western Po plain (-4% in correspondence with two regions of strong crustal thickening and negative Bouguer anomaly. In contrast, high Pn velocities are imaged beneath the inner side of the Alps (+4% indicating the presence of high velocity and density lower crust-upper mantle. The Ligurian sea shows high Pn velocities close to the Ligurian coastlines (+3% and low Pn velocities (-1.5% in the middle of the basin in agreement with the upper mantle velocity structure revealed by seismic refraction profiles.

  12. Technology and function of grooved abraders in the early Neolithic of northwestern Europe

    Directory of Open Access Journals (Sweden)

    Caroline Hamon

    2016-10-01

    Full Text Available Found sporadically in late Palaeolithic and Mesolithic contexts, grooved abraders are among the most common tools found in Linear Pottery and Villeneuve-Saint-Germain settlements in north-western Europe (5,100-4,700 BCE. This paper presents an overview of the technical and functional characteristics of these tools in early Neolithic domestic contexts. Despite different blank morphologies and sizes, these tools tend to be relatively small in size and are generally not shaped. They are characterized by the use of a very specific raw material: low cohesive and generally ferruginous sandstones, chosen because their abrasiveness is enhanced through use. A classification of the different types of grooves is proposed, based on their shape, depth, section and localization. These characteristics are combined with use-wear analysis in order to propose a number of functional interpretations. Far from the widespread hypothesis that these tools functioned as shaft straighteners, we argue on the basis of the use-wear analysis and archaeological associations of items that these tools were primarily involved in the manufacture of bone and lithic tools, as well as of schist and limestone personal ornaments. They are evidence of the generalization and diversification of polishing and abrading techniques in the technical system of the first Neolithic populations. As such, they contribute to defining a whole new technical paradigm and are an essential element in any definition of the Neolithic.

  13. Late Pleistocene ecological, environmental and climatic reconstruction based on megafauna stable isotopes from northwestern Chilean Patagonia

    Science.gov (United States)

    González-Guarda, Erwin; Domingo, Laura; Tornero, Carlos; Pino, Mario; Hernández Fernández, Manuel; Sevilla, Paloma; Villavicencio, Natalia; Agustí, Jordi

    2017-08-01

    Stable isotope analyses have been performed on the bioapatite (δ13C; δ18O) and collagen (δ13C; δ15N) of four late Pleistocene South American megafaunal taxa (Notiomastodon platensis, Equus andium, cf. Hemiauchenia paradoxa and Xenarthra indet.) to evaluate paleoclimatic and paleoenvironmental conditions as well as paleoecological features of this time period. The analyzed megafauna was found at several locations in the northwestern Chilean Patagonia (38°-42°S, 74°-71°W). The bioapatite δ13C values indicated the presence of C3 vegetation ranging from forestal to woodland areas. The collagen δ15N values pointed to temperate and humid ecosystems, and to the consumption of shrubs, trees, grasses and sedges. Mean annual temperatures estimated from bioapatite δ18OPO4 values show a similarity to modern temperatures and suggested that the megafauna under study may have lived during warm stages (interstadials) of the late Pleistocene. When comparing our results with those obtained from other South American regions, we find that the diet of this particular Chilean megafauna appears to have been more influenced by resource availability than by the potential dietary range of the taxa.

  14. Spectral discrimination of uranium-mineralized breccia pipes in northwestern Arizona

    International Nuclear Information System (INIS)

    Kwarteng, A.Y.; Goodell, P.C.; Pingitore, N.E. Jr.; Wenich, K.J.

    1989-01-01

    The price of uranium is currently the lowest in more than a decade. The only type of uranium deposit that is economically viable in the depressed uranium market is such high-grade ore as the unconformity type found in Canada and Australia. Exploration for uranium-bearing breccia pipes in northwestern Arizona by both domestic and foreign companies is currently active because of the relatively high-grade ore they contain and their tendency to be polymetallic. In the US, uranium-mineralized breccia pipes are one of the few deposits that can compete in the current market. A stepwise discriminant analysis was performed on spectral data acquired from the field, laboratory, and Landsat thematic mapper (TM). The principal objectives were (1) to investigate the fundamental differences in the spectral properties of outcrops on the surface of breccia pipes and the background, (2) to choose TM bandpasses that were statistically optimum for distinguishing between breccia pipes and the background, and (3) to compare the results of the field, laboratory, and TM digital data which were acquired by different instruments having different spatial and spectral resolutions

  15. Gastrointestinal Helminths and Ectoparasites in the Stray Cats (Felidae: Felis catus) of Ahar Municipality, Northwestern Iran

    Science.gov (United States)

    YAKHCHALI, Mohammad; HAJIPOUR, Nasser; MALEKZADEH-VIAYEH, Reza; ESMAEILNEJAD, Bijan; NEMATI-HARAVANI, Taher; FATHOLLAHZADEH, Mohammad; JAFARI, Rasool

    2017-01-01

    Background: The stray cats are considered as the sources of emerging humans and domestic livestock pathogens and the zoonoses of public health importance. The present study was aimed to elucidate intestinal helminth infections and infestation with ectoparasites of the stray cats of Ahar City, northwestern Iran. Methods: Totally, 51 stray cats were randomly trapped from different parts of the city between Mar and Nov 2013. The cats were assessed for ectoparasites by hair brushing, skin scraping, acetate tape preparation and othic swabs. They were euthanized and inspected for helminths infection. Results: Overall prevalence of helminths and flea were 44/51 (86.3%) and 31/51 (60.78%), respectively. The infection rates were significantly different among different age groups (PDipylidium caninum (29.41%), T. hydatigena (19.6%)) were identified. The predominant infectious helminths in all the infected cats were T. cati (86.3% with egg per gram of feces 27.75±9). Of the 270 collected fleas, two species of Ctenocephalides felis (80%) and C. canis (20%) were notably frequent in the cats aged 2-3-year-old. The average number of fleas per each infected cat was recorded as 5.29, with no incidence of cross-infection. Conclusion: The results indicated the high rate of helminths infections and flea infestation in the urban stray cats of which Toxocara cati and Ctenocephalides felis may play important roles as zoonotic agents in the region. PMID:28761492

  16. Distribution of Iodine-129 in the northwestern North Pacific Ocean between Jan and Feb 2012

    International Nuclear Information System (INIS)

    Suzuki, Takashi; Otosaka, Shigeyoshi; Kuwabara, Jun

    2013-01-01

    To evaluate the impact of "1"2"9I from the Fukushima Daiichi Nuclear Power Plant (FNPP) accident, we measured "1"2"9I concentration at three stations: Oyashio-area, transition-area and Kuroshio-area in the northwestern Pacific Ocean. Accident-derived "1"2"9I in surface seawaters was detected at all stations and the highest concentration was observed at the transition-area, 550 km east of the FNPP. The depth profiles show that the accident-derived "1"2"9I was penetrated to 150 m and 200 m depths at the Oyashio-area and transition area, respectively. At the Kuroshio-area, "1"2"9I showed a maximum around 400 - 500 m depth (σ_0=26.0 - 26.2). This is probably due to the isopycnal mixing of surface seawater around 37 N. The highest inventory of accident-derived "1"2"9I was observed at Kuroshio-area. (author)

  17. HYDROCARBON POLLUTION IN THE NORTH-WESTERN PART OF THE CASPIAN SEA

    Directory of Open Access Journals (Sweden)

    E. V. Ostrovskaya

    2016-01-01

    Full Text Available Aim. The paper is aimed to estimate the current level of hydrocarbon pollution of the marine environment in the North-Western part of the Caspian Sea.Methods. The paper discusses the results of three-year studies conducted in 2012-2014 within the framework of Roshydromet’s Programme of monitoring of transboundary waters of the Caspian Sea. Spatial distribution of concentrations of hydrocarbons (total and polyaromatic in water and bottom sediments of the area was analysed. Concentrations of total hydrocarbons were determined by means of infrared spectrometry and PAHs – of gas chromatography with mass spectrometry.Results. The range of the total hydrocarbons in the area’s water is from slight traces to 240 µg/l, in sediments – from traces to 114 µg/g (dry weight. Total concentrations of PAHs in water varied from traces to 321 ng/l, in sediments – from traces to 699 ng/g (dry weight. For the source identification, data of satellite monitoring of the area were used. The data showed increasing input of hydrocarbons coming into the marine environment with discharges from vessels.Conclusion. The results of these studies are compared to those of previous research and show that the level of hydrocarbons in the area is typical for slightly polluted areas.

  18. Geomorphic evaluation of erosional stability at reclaimed surface mines in northwestern Colorado. Water Resources Investigation

    International Nuclear Information System (INIS)

    Elliott, J.G.

    1990-01-01

    The report identifies geomorphic, pedologic, vegetation, and hydrologic conditions that are associated with erosion of reclaimed surface-mined lands in northwestern Colorado. The report also presents methods for determining the appropriate values of geomorphic variables that can be manipulated during reclamation to increase erosional stability. A section on geomorphic principles associated with erosion of reclaimed land surfaces is designed for use as a primer by mine personnel and reclamation planners. The areas of interest in the study were those that were reclaimed under jurisdiction of current (1988) SMCRA reclamation regulations, yet were still affected by relatively rapid erosion rates several years after reclamation activities were completed. Geomorphic, pedologic, vegetation, and hydrologic data were collected onsite and from topographic maps. Data from reclaimed areas undergoing accelerated erosion were compared with data from reclaimed areas undergoing minimal erosion to identify conditions that controlled erosion on reclaimed surface-mined lands and to identify some postmining equilibrium landform characteristics. These data also were used to develop threshold relations

  19. Economic feasibility of biomass gasification for power generation in three selected communities of northwestern Ontario, Canada

    International Nuclear Information System (INIS)

    Upadhyay, Thakur Prasad; Shahi, Chander; Leitch, Mathew; Pulkki, Reino

    2012-01-01

    Biomass gasification is expected to be an attractive option among other competitive applications of biomass conversion for bio-energy. This study analyzes economic feasibility of biomass gasification power generating plants in three selected communities (Ignace, Nipigon and Kenora) of northwestern Ontario. The major variables considered in the model are harvesting and handling costs, logistic costs for biomass feedstock delivery and storage, capital costs of power plant by scales, operation and maintenance costs, labor costs, capital financing costs and other regulatory costs. GIS analysis was undertaken to estimate the distance class matrix to apportion the biomass feedstock supply side from different forest management units. Total cost per MW h power production at a 50 MW scale ranges from CAD 61.89 to CAD 63.79. Total cost per unit of electricity production decreases significantly as plant capacity increases due to economy of scale in the production system. Further, the locations of plants explained the cost variability. - Highlights: ► We model feasibility of gasification power plants in three rural communities. ► The variables considered in the model are logistics, operational and capital costs. ► Mean distance from each community to different forest units are estimated with GIS. ► Total cost per MWh at a 50 MW scale ranges from CAD 61.89 to CAD 63.79. ► Total cost decreases with increase in plant capacity.

  20. Pemphigus in North-Western Yemen: A therapeutic study of 75 cases.

    Science.gov (United States)

    Khatri, Mishri Lal

    2016-01-01

    The incidence of pemphigus, though not documented, seems to be quite high in Yemen. There is no universal consensus on the treatment of this disease. The aim was to evaluate the efficacy and side effects of different therapeutic regimens used in patients of pemphigus in North-Western Yemen. Seventy-five Yemeni patients (39 males and 36 females) were included. Diagnosis was based on clinical features, histopathology and the Tzanck test. Results of treatment with these different therapeutic regimens were compared: (1) dexamethasone-cyclophosphamide pulse (DCP), (2) dexamethasone pulse with oral azathioprine, (3) oral prednisolone with azathioprine, (4) oral prednisolone with oral cyclophosphamide, and (5) prednisolone monotherapy. Pemphigus vulgaris (PV) was diagnosed in 46 patients, pemphigus foliaceus (PF) in 23, pemphigus vegetans (PVEG) in 5 and pemphigus herpetiformis (PH) in one. Among the 16 patients who received regular DCP therapy, 13 were in remission for 6 months to 11 years without medications (phase 4). Remission without pharmacotherapy could not be achieved with the other regimens and steroid-induced side-effects appeared to be more than with DCP. Immunofluorescence was not available to confirm the diagnosis of pemphigus. Randomization was not done. The DCP regimen seemed to be superior to the other regimens used.

  1. Evidence for early irrigation at Bat (Wadi Sharsah, northwestern Oman) before the advent of farming villages

    Science.gov (United States)

    Desruelles, Stéphane; Fouache, Eric; Eddargach, Wassel; Cammas, Cecilia; Wattez, Julia; Beuzen-Waller, Tara; Martin, Chloé; Tengberg, Margareta; Cable, Charlotte; Thornton, Christopher; Murray, Andrew

    2016-10-01

    Decades of archaeological research in southeastern Arabia (Oman and the UAE) have provided a good understanding of the evolution of human societies in this arid region, with the transition from mobile pastoralism to settled agricultural villages occurring at the start of the Hafit period (ca. 3100-2700 BCE). The delayed adoption of farming, ceramics, mudbrick architecture, metallurgy, and other technologies until the start of the 3rd millennium BCE has been a particularly salient feature of this region relative to its neighbours in Mesopotamia, southern Iran, and northwestern South Asia. However, recent geoarchaeological research at the World Heritage Site of Bat, situated within the Wadi Sharsah valley in northwest Oman, has provided evidence of irrigation practices that have been dated to the early-mid 4th millennium BCE. While direct evidence of farming from this early period remains elusive, the presence of irrigated fields at this time raises new questions about the supposedly mobile pastoralist groups of the Arabian Neolithic and the beginning of farming practices in the region.

  2. Drama of the commons in small-scale shrimp aquaculture in northwestern, Sri Lanka

    Directory of Open Access Journals (Sweden)

    Eranga Kokila Galappaththi

    2015-03-01

    Full Text Available Aquaculture, and shrimp aquaculture in particular, can have major social and environmental impacts. However, aquaculture remains an understudied area in commons research. Can aspects of commons theory be applied to solve problems of aquaculture? We examined three coastal community-based shrimp aquaculture operations in northwestern Sri Lanka using a case study approach. These shrimp farms were individually owned by small producers and managed under local-level rules designed by cooperatives (samithis. The common-pool resource of major interest was water for aquaculture ponds, obtained from an interconnected common water body. We evaluated the shrimp farming social-ecological system by using Ostrom’s design principles for collective action. Key elements of the system were: clearly defined boundaries; collaboratively designed crop calendar, bottom-up approach involving community associations, multi-level governance, and farmers-and-government collaborative structures. Together, these elements resolved the excludability and subtractability problems of commons by establishing boundary and membership rules and collective choice rules.

  3. Typhoon Rammasun-Induced Near-Inertial Oscillations Observed in the Tropical Northwestern Pacific Ocean

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    Eung Kim

    2013-01-01

    Full Text Available Wind-induced near-inertial oscillations (NIOs have been known to propagate their energy downward and equatorward, yet few observations have confirmed this in tropical regions. Using measurements from a moored ADCP in the tropical northwestern Pacific, we report an energetic NIO event associated with Typhoon Rammasun in May 2008, when an anti-cyclonic warm eddy existed around the mooring site. Our analyses reveal that the anti-cyclonic eddy traps the NIO energy at two layers around 120 and 210 m where the buoyancy frequency show high values. The NIO energy continuously decays at layers below its maximum at 210 m, and disappears at depths below the thermocline. During their propagation from 137 to 649 stretched-meter depths (equivalent to 100 - 430 m, NIOs shift their frequencies from 0.92f to 1.05f probably due to the effective f, which changes its magnitude from smaller to larger than local inertial frequency f in the anti-cyclonic eddy. In addition, their vertical energy propagation becomes faster from 0.17 to 0.64 mm s-1. Decomposition of downward and upward NIO energy propagation shows that the typhoon-induced NIOs remain 29% of their energy in the upper layer, and transfer 71% to the subsurface layers. Our results suggest that typhoon-induced NIOs interacting with meso-scale eddies can play an important role in providing the energy source available for ocean mixing in the tropical regions.

  4. Climate-driven speedup of alpine treeline forest growth in the Tianshan Mountains, Northwestern China.

    Science.gov (United States)

    Qi, Zhaohuan; Liu, Hongyan; Wu, Xiuchen; Hao, Qian

    2015-02-01

    Forest growth is sensitive to interannual climatic change in the alpine treeline ecotone (ATE). Whether the alpine treeline ecotone shares a similar pattern of forest growth with lower elevational closed forest belt (CFB) under changing climate remains unclear. Here, we reported an unprecedented acceleration of Picea schrenkiana forest growth since 1960s in the ATE of Tianshan Mountains, northwestern China by a stand-total sampling along six altitudinal transects with three plots in each transect: one from the ATE between the treeline and the forest line, and the other two from the CFB. All the sampled P. schrenkiana forest patches show a higher growth speed after 1960 and, comparatively, forest growth in the CFB has sped up much slower than that in the ATE. The speedup of forest growth at the ATE is mainly accounted for by climate factors, with increasing temperature suggested to be the primary driver. Stronger water deficit as well as more competition within the CFB might have restricted forest growth there more than that within the ATE, implying biotic factors were also significant for the accelerated forest growth in the ATE, which should be excluded from simulations and predictions of warming-induced treeline dynamics. © 2014 John Wiley & Sons Ltd.

  5. Time--temperature relation of embryonic development in the northwestern salamander, Ambystoma gracile

    Energy Technology Data Exchange (ETDEWEB)

    Brown, H A

    1976-04-01

    A field and laboratory study on temperature-related embryonic development of Ambystoma gracile was made on a population from northwestern Washington. Natural spawning began in the beaver pond during early March, and the duration of embryonic development (stages 1 to 46) was about 62 days. Average water temperature in the pond during embryonic development was 8.5/sup 0/C (range, 4.4 to 14.3/sup 0/C). The laboratory data of embryonic development at constant temperatures show that the limits of temperature tolerance are about 5 to 22.5/sup 0/C. Rate of development was measured by determining time required to develop from first cleavage (stage 2) to gill circulation (stage 37); representative rates are 12.7 days at 20/sup 0/C, 27 days at 12/sup 0/C, and 89 days at 7/sup 0/C. Embryos of A. gracile have the slowest rate of development when compared with embryos of four other species of Ambystoma (maculatum, mexicanum, tigrinum, and jeffersonianum) and with embryos of three Pacific Northwest frogs (Ascaphus truei, Rana aurora, and Hyla regilla).

  6. Prevalence of zoonotic intestinal helminths of canids in moghan plain, northwestern iran.

    Science.gov (United States)

    Zare-Bidaki, M; Mobedi, I; Ahari, S Sadeghieh; Habibizadeh, S; Naddaf, Sr; Siavashi, Mr

    2010-06-01

    The present study was aimed to elucidate the status of intestinal helminth infections in canids of Moghan Plain, northwestern Iran. Eighty-five intestine samples from dead or shot wild canids, 59 fecal samples from sheepdogs and 5 from red foxes were collected from 2006 to 2008 and examined in Parasitology department of Pasteur Institute of Iran. Generally, adult worms, larvae, and eggs of 13 species of various parasitic helminths were recovered. Necropsy examinations showed that 96.47% animals harbored at least one helminth species. The prevalence of different species in necropsy were Mesocestoides sp. 84.7%, Rictolaria spp. 55.3%, Macranthorhynchus hirudinaceus 45.9%, Toxocara canis 43.5%, Toxascaris spp. 35.3%, Joyeuxiella sp. 34.1%; hookworms; 22.4%, Taenia spp. 11.8%, Alaria spp. 2.4% and Dipylidium caninum 1.2%. Besides, eggs belonging to 10 species of parasitic helminths were identified in 46 fecal samples and generally, 30.9% of samples harbored eggs of at least one helminth species. The high prevalence of various helminth infections among canids in Moghan plain and contamination of environment by helminths eggs may increase the risk of infection for native people.

  7. Prevalence of Zoonotic Intestinal Helminths of Canids in Mog­han Plain, Northwestern Iran

    Directory of Open Access Journals (Sweden)

    M Zare-Bidaki

    2010-06-01

    Full Text Available Background: The present study was aimed to elucidate the status of intestinal hel­minth infec­tions in canids of Moghan Plain, northwestern Iran.Methods: Eighty-five intestine samples from dead or shot wild canids, 59 fecal samples from sheepdogs and 5 from red foxes were collected from 2006 to 2008 and examined in Parasitology department of Pasteur Institute of Iran.Results: Generally, adult worms, larvae, and eggs of 13 species of various parasitic hel­minths were recovered. Necropsy examinations showed that 96.47% animals harbored at least one helminth species. The prevalence of different species in necropsy were Mesoces­toides sp. 84.7%, Rictolaria spp. 55.3%, Macranthorhynchus hirudinaceus 45.9%, Toxocara canis 43.5%, Toxas­caris spp. 35.3%, Joyeuxiella sp. 34.1%; hook­worms; 22.4%, Taenia spp. 11.8%, Alaria spp. 2.4% and Dipylidium caninum 1.2%. Be­sides, eggs belonging to 10 species of parasitic helminths were identified in 46 fecal sam­ples and generally, 30.9% of samples harbored eggs of at least one helminth species.Conclusion: The high prevalence of various helminth infections among canids in Mog­han plain and contamination of environment by helminths eggs may increase the risk of infection for native peo­ple.

  8. Phylogeography and pigment type diversity of Synechococcus cyanobacteria in surface waters of the northwestern pacific ocean.

    Science.gov (United States)

    Xia, Xiaomin; Partensky, Frédéric; Garczarek, Laurence; Suzuki, Koji; Guo, Cui; Yan Cheung, Shun; Liu, Hongbin

    2017-01-01

    The widespread unicellular cyanobacteria Synechococcus are major contributors to global marine primary production. Here, we report their abundance, phylogenetic diversity (as assessed using the RNA polymerase gamma subunit gene rpoC1) and pigment diversity (as indirectly assessed using the laterally transferred cpeBA genes, encoding phycoerythrin-I) in surface waters of the northwestern Pacific Ocean, sampled over nine distinct cruises (2008-2015). Abundance of Synechococcus was low in the subarctic ocean and South China Sea, intermediate in the western subtropical Pacific Ocean, and the highest in the Japan and East China seas. Clades I and II were by far the most abundant Synechococcus lineages, the former dominating in temperate cold waters and the latter in (sub)tropical waters. Clades III and VI were also fairly abundant in warm waters, but with a narrower distribution than clade II. One type of chromatic acclimater (3dA) largely dominated the Synechococcus communities in the subarctic ocean, while another (3dB) and/or cells with a fixed high phycourobilin to phycoerythrobilin ratio (pigment type 3c) predominated at mid and low latitudes. Altogether, our results suggest that the variety of pigment content found in most Synechococcus clades considerably extends the niches that they can colonize and therefore the whole genus habitat. © 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.

  9. Population genetic structure of the point-head flounder, Cleisthenes herzensteini, in the Northwestern Pacific.

    Science.gov (United States)

    Xiao, Yongshuang; Zhang, Yan; Yanagimoto, Takashi; Li, Jun; Xiao, Zhizhong; Gao, Tianxiang; Xu, Shihong; Ma, Daoyuan

    2011-02-01

    Intraspecific phylogenies can provide useful insights into how populations have been shaped by historical and contemporary processes. To determine the population genetic structure and the demographic and colonization history of Cleisthenes herzensteini in the Northwestern Pacific, one hundred and twenty-one individuals were sampled from six localities along the coastal regions of Japan and the Yellow Sea of China. Mitochondrial DNA variation was analyzed using DNA sequence data from the 5' end of control region. High levels of haplotype diversity (>0.96) were found for all populations, indicating a high level of genetic diversity. No pattern of isolation by distance was detected among the population differentiation throughout the examined range. Analyses of molecular variance (AMOVA) and the conventional population statistic Fst revealed no significant population genetic structure among populations. According to the exact test of differentiation among populations, the null hypothesis that C. herzensteini within the examined range constituted a non-differential mtDNA gene pool was accepted. The demographic history of C. herzensteini was examined using neutrality test and mismatch distribution analyses and results indicated Pleistocene population expansion (about 94-376 kya) in the species, which was consistent with the inference result of nested clade phylogeographical analysis (NCPA) showing contiguous range expansion for C. herzensteini. The lack of phylogeographical structure for the species may reflect a recent range expansion after the glacial maximum and insufficient time to attain migration-drift equilibrium.

  10. Mechanics and Partitioning of Deformation of the Northwestern Okhostk Plate, Northeast Russia

    Science.gov (United States)

    Hindle, D.; Mackey, K.; Fujita, K.

    2007-12-01

    The tectonic evolution and present day deformation of northeastern Russia remains one of the major challenges in plate tectonics. Arguments over the existence of at least a separate Okhotsk plate between North America and Eurasia appear to be resolved on the basis of the latest GPS studies combined with elastic modeling. The question of the mechanical behaviour of the Okhotsk plate, caught between the slowly, obliquely converging North American and Eurasian plates now becomes important. We present an analysis of geological lineaments, micro-seismicity, total seismic moment release and seismic deformation rate and GPS campaign data and global plate tectonic model data (REVEL) to estimate the likelihood of future seismicity and the relative amount of elastic and viscous deformation of the lithosphere of the northwestern Okhotsk plate. We find that it is likely that the Okhotsk plate is cracked into slivers, but that rates of relative motion of these slivers are close to indistinguishable from the behaviour of a single, rigid plate. The analysis also suggests the upper bound for large earthquakes in the region to be Mw 7-7.5 which we expect to occur only on the plate boundary fault itself. This fits geological evidence for a long term offset rate 5-10 times higher on the major plate boundary fault than other lineaments cutting the Okhotsk plate itself.

  11. Agency and Resilience: Teachings of Pikangikum First Nation Elders, Northwestern Ontario

    Directory of Open Access Journals (Sweden)

    Andrew M. Miller

    2013-09-01

    Full Text Available Although scholars of social-ecological resilience propose unity between humans and the natural world, much of this work remains based on Cartesian division of mind and body that denies it. We present an example of a unified system of resilience thinking shared with us by Anishinaabe (Ojibway elders of Pikangikum First Nation, northwestern Ontario. The elders' views of boreal forest disturbance and renewal are distinct from western scientific approaches in their recognition of agency, the ability to individually express free will in nonhuman beings including animals, plants, rocks, and forest fire within their landscape. Pikangikum elders perceive that, if relationships based on respect, reciprocity, and noninterference are maintained with other agents, renewal will continue. The proposition of living landscapes composed of diverse nonhuman agents poses challenges to collaboration with western worldviews, which view nature largely as mechanistic and without moral standing. We suggest that a greater attention to nonwestern ontologies can contribute to productive cross-cultural partnerships directed toward fostering resilience.

  12. Nitrate Determination of Vegetables in Varzeghan City, North-western Iran

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    Parviz Nowrouz

    2012-12-01

    Full Text Available Background: Vegetables play an important role in human nutrition. Nitrate content is a signifi-cant quality criterion to determine characteristic of vegetables. About 80% of nitrate intake in human is from vegetables and fruits. High dietary intake of nitrate is seen as an undesirable be-cause of its association with gastric cancer and infantile methemoglobinemia. Varzeghan, North-western Iran is one of the cities with high Age-standardized incidence rates (ASR of gastric can-cer in Iran. Currently, in Varzeghan there is no available and accurate information describing ni-trate concentration as one of the important risk factors of vegetables for human consumption.Methods: In this cross sectional study totally 11 types of vegetables (cabbage, lettuce, spinach, parsley, coriander, dill, leek, fenugreek, tarragon, fumitory and mint from several different green-grocery of Varzeghan were collected in spring (April and autumn (November and December 2011 and their nitrate contents were analyzed.Results: Mean nitrate contents at the above noted fresh vegetables were 161, 781, 83, 707, 441,501, 1702, 684, 805, 772 and 191 mg NO3-kg-1 respectively. In none of the 11 fresh vegetablesnitrate content were not more than established limitations.Conclusion: Nitrate concentrations were below of others reported at different countries. The mean concentration of nitrate at all vegetables in autumn was higher than in spring significantly.

  13. Children's education and home electrification: A case study in northwestern Madagascar

    Energy Technology Data Exchange (ETDEWEB)

    Rajaona Daka, Karen, E-mail: karen_rajaona@yahoo.f [University of Versailles St Quentin en Yvelines, 47 Bd Vauban, 78047 Guyancourt Cedex (France); Ballet, Jerome, E-mail: jballetfr@yahoo.f [Centre of Ethics and Economics for Environment and Development in Madagascar, University of Antananarivo, BP905, 101 Antananarivo (Madagascar); Institut de Recherche pour le Developpement, UMI Resiliences, 32 Avenue Henri Varagnat, 93143 Bondy Cedex (France)

    2011-05-15

    Assessments of the impact of electrification on the quality of life of households in developing countries have increased over the last decade. One aspect that has still received little attention is education and the ability of children to keep up at school. The underlying hypothesis is that electrification enables children to do their homework in the evening and so keep up with their school work. To this first hypothesis we add a second one, concerning the relation between access to electricity and attendance to school according to gender. Although most household tasks are carried out by the mothers, their daughters are also involved, and electrification could have a beneficial effect by making easier for girls to do their homework in the evening and easier for the mothers to help them. We will check the validity of these hypotheses using a case study of 162 children attending school in a small town in northwestern Madagascar. - Research Highlights: {yields} We use a sample of 162 children in Madagascar to test the effect of access to the electricity supply in home to the education of children. {yields} We also test the effect to the electricity supply in home to gender-specificities. {yields} Our results confirm that electrification can contribute to reduce social reproduction with regard to education. {yields} Our results also show that electrification helps to reduce gender inequalities.

  14. Applications of geographic information systems and remote sensing techniques to conservation of amphibians in northwestern Ecuador

    Directory of Open Access Journals (Sweden)

    Mariela Palacios González

    2015-01-01

    Full Text Available The biodiversity of the Andean Chocó in western Ecuador and Colombia is threatened by anthropogenic changes in land cover. The main goal of this study was to contribute to conservation of 12 threatened species of amphibians at a cloud forest site in northwestern Ecuador, by identifying and proposing protection of critical areas. We used Geographic Information Systems (GIS and remote sensing techniques to quantify land cover changes over 35 years and outline important areas for amphibian conservation. We performed a supervised classification of an IKONOS satellite image from 2011 and two aerial photographs from 1977 and 2000. The 2011 IKONOS satellite image classification was used to delineate areas important for conservation of threatened amphibians within a 200 m buffer around rivers and streams. The overall classification accuracy of the three images was ≥80%. Forest cover was reduced by 17% during the last 34 years. However, only 50% of the study area retained the initial (1977 forest cover, as land was cleared for farming and eventually reforested. Finally, using the 2011 IKONOS satellite image, we delineated areas of potential conservation interest that would benefit the long term survival of threatened amphibian species at the Ecuadorian cloud forest site studied.

  15. Regional-Scale Drivers of Forest Structure and Function in Northwestern Amazonia

    Science.gov (United States)

    Higgins, Mark A.; Asner, Gregory P.; Anderson, Christopher B.; Martin, Roberta E.; Knapp, David E.; Tupayachi, Raul; Perez, Eneas; Elespuru, Nydia; Alonso, Alfonso

    2015-01-01

    Field studies in Amazonia have found a relationship at continental scales between soil fertility and broad trends in forest structure and function. Little is known at regional scales, however, about how discrete patterns in forest structure or functional attributes map onto underlying edaphic or geological patterns. We collected airborne LiDAR (Light Detection and Ranging) data and VSWIR (Visible to Shortwave Infrared) imaging spectroscopy measurements over 600 km2 of northwestern Amazonian lowland forests. We also established 83 inventories of plant species composition and soil properties, distributed between two widespread geological formations. Using these data, we mapped forest structure and canopy reflectance, and compared them to patterns in plant species composition, soils, and underlying geology. We found that variations in soils and species composition explained up to 70% of variation in canopy height, and corresponded to profound changes in forest vertical profiles. We further found that soils and plant species composition explained more than 90% of the variation in canopy reflectance as measured by imaging spectroscopy, indicating edaphic and compositional control of canopy chemical properties. We last found that soils explained between 30% and 70% of the variation in gap frequency in these forests, depending on the height threshold used to define gaps. Our findings indicate that a relatively small number of edaphic and compositional variables, corresponding to underlying geology, may be responsible for variations in canopy structure and chemistry over large expanses of Amazonian forest. PMID:25793602

  16. Relict ooids off northwestern India: Inferences on their genesis and late Quaternary sea level

    Science.gov (United States)

    Purnachandra Rao, V.; Milliman, John D.

    2017-08-01

    Relict carbonate sands dominated by ooids and faecal pellets are common on the continental shelf, between 60 and 110 m, off northwestern India. The shiny tan/white aragonitic ooids closely resemble modern Bahamian ooids, with cortex thicknesses varying from stacked tubules, similar in appearance to algal or microbial filaments. Bacteria associated with the decaying organic sheath of the laminae may have played an important role in subsequent aragonite precipitation. Bladed or radial aragonite microstructures are secondary features in the cortex, apparently formed during early diagenesis by mineralization of organic matter associated with the tangential laminae. Calibrated ages of the ooids range between 9.8 and > 23 ka BP, and δ18O values suggest that these relict ooids formed during cooler and drier post-LGM conditions and later during the re-intensified Holocene monsoon climate. An age vs. depth plot suggests that most of the ooids formed at water depths between 10 and - 40 m, thereby calling into question whether relict shelf ooids are reliable indicators of past sea level.

  17. A game theoretic model of the Northwestern European electricity market-market power and the environment

    International Nuclear Information System (INIS)

    Lise, Wietze; Linderhof, Vincent; Kuik, Onno; Kemfert, Claudia; Ostling, Robert; Heinzow, Thomas

    2006-01-01

    This paper develops a static computational game theoretic model. Illustrative results for the liberalising European electricity market are given to demonstrate the type of economic and environmental results that can be generated with the model. The model is empirically calibrated to eight Northwestern European countries, namely Belgium, Denmark, Finland, France, Germany, The Netherlands, Norway, and Sweden. Different market structures are compared, depending on the ability of firms to exercise market power, ranging from perfect competition without market power to strategic competition where large firms exercise market power. In addition, a market power reduction policy is studied where the near-monopolies in France and Belgium are demerged into smaller firms. To analyse environmental impacts, a fixed greenhouse gas emission reduction target is introduced under different market structures. The results indicate that the effects of liberalisation depend on the resulting market structure, but that a reduction in market power of large producers may be beneficial for both the consumer (i.e. lower prices) and the environment (i.e. lower greenhouse gas permit price and lower acidifying and smog emissions)

  18. Tectonic significance of dykes in the Sarnu-Dandali alkaline complex, Rajasthan, northwestern Deccan Traps

    Directory of Open Access Journals (Sweden)

    Anjali Vijayan

    2016-09-01

    Full Text Available Whether swarms of preferentially oriented dykes are controlled by regional stress fields, or passively exploit basement structural fabric, is a much debated question, with support for either scenario in individual case studies. The Sarnu-Dandali alkaline complex, near the northwestern limit of the Deccan Traps continental flood basalt province, contains mafic to felsic alkaline volcano-plutonic rocks and carbonatites. The complex is situated near the northern end of the 600 km long, NNW–SSE-trending Barmer-Cambay rift. Mafic enclave swarms in the syenites suggest synplutonic mafic dykes injected into a largely liquid felsic magma chamber. Later coherent dykes in the complex, of all compositions and sizes, dominantly strike NNW–SSE, parallel to the Barmer-Cambay rift. The rift formed during two distinct episodes of extension, NW–SE in the early Cretaceous and NE–SW in the late Cretaceous. Control of the southern Indian Dharwar structural fabric on the rift trend, as speculated previously, is untenable, whereas the regional Precambrian basement trends (Aravalli and Malani run NE–SW and NNE–SSW. We therefore suggest that the small-scale Sarnu-Dandali dykes and the much larger-scale Barmer-Cambay rift were not controlled by basement structure, but related to contemporaneous, late Cretaceous regional ENE–WSW extension, for which there is varied independent evidence.

  19. Atmospheric occurrence, transport and gas-particle partitioning of polychlorinated biphenyls over the northwestern Pacific Ocean

    Science.gov (United States)

    Wu, Zilan; Lin, Tian; Li, Zhongxia; Li, Yuanyuan; Guo, Tianfeng; Guo, Zhigang

    2017-10-01

    Ship-board air samples were collected during March to May 2015 from the East China Sea (ECS) to the northwestern Pacific Ocean (NWP) to explore the atmospheric occurrence and gas-particle partitioning of polychlorinated biphenyls (PCBs) when the westerly East Asian Monsoon prevailed. Total PCB concentrations in the atmosphere ranged from 56.8 to 261 pg m-3. Higher PCB levels were observed off the coast and minor temperature-induced changes showed that continuous emissions from East Asia remain as an important source to the regional atmosphere. A significant relationship between Koa (octanol-air partition coefficient) and KP (gas-particle partition coefficient) for PCBs was observed under continental air masses, suggesting that land-derived organic aerosols affected the PCB gas-particle partitioning after long-range transport, while an absence of this correlation was identified in marine air masses. The PCB partitioning cannot be fully explained by the absorptive mechanism as the predicted KP were found to be 2-3 orders of magnitude lower than the measured Kp, while the prediction was closely matched when soot adsorption was considered. The results suggested the importance of soot carbon as a transport medium for PCBs during their long-range transport and considerable impacts of continental outflows on PCBs across the downwind area. The estimated transport mass of particulate PCBs into the ECS and NWP totals 2333 kg during the spring, constituting ca. 17% of annual emission inventories of unintentionally produced PCB in China.

  20. Hyporheic fauna from interstitial of the Someş River basin (Transylvania, northwestern Romania

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    Claudia Pavelescu

    2009-01-01

    Full Text Available Biodiversity in hyporheic habitats (interstitial water habitats in river bank sediments has been studied on Someşul Cald (Warm Someş and Someşul Rece (Cold Someş River (north-western Romania, Transylvania, from March to October 2004. pH and electrical conductivity were measured monthly at each site, and animals were collected with the Karaman-Chappuis method and by filtering water through a hand-net. The relative abundance of the best-represented hyporheic invertebrates (oligochaetes and insect larvae was higher in Someşul Cald interstitial habitats than in Someşul Rece. The focus was directed to the role of water mites (Acari, Hydrachnidia, cyclopoid copepods (Crustacea, Copepoda, Cyclopoida and oligochaetes (Annelida, Oligochaeta in hyporheic communities. Nine water mites and five cyclopoid species were identified in five sampling sites of the two rivers. Their higher diversity was recorded in two stations on the Someşul Cald River. The cyclopoid copepod Diacyclops disjunctus (Thallwitz, 1927 is a new record for Romania. As for oligochaetes, 17 species were identified and their higher diversity was recorded on Someşul Rece River. Canonical Correspondence Analysis (CCA shows that presence of some water mites and cyclopoid species can be associated with measured physicochemical parameters (pH, electrical conductivity. Principal Component Analysis (PCA shows similarities between stations and the dominant taxa in some samples.

  1. Prevalence and genetic diversity of Bartonella strains in rodents from northwestern Mexico.

    Science.gov (United States)

    Rubio, André V; Ávila-Flores, Rafael; Osikowicz, Lynn M; Bai, Ying; Suzán, Gerardo; Kosoy, Michael Y

    2014-12-01

    Bartonella infections were investigated in wild rodents from northwestern Chihuahua, Mexico. A total of 489 rodents belonging to 14 species were surveyed in four areas. Bartonella bacteria were cultured from 50.1% of rodent samples (245/489). Infection rates ranged from 0% to 83.3% per rodent species, with no significant difference between sites except for Cynomys ludovicianus. Phylogenetic analyses of the citrate synthase gene (gltA) of the Bartonella isolates revealed 23 genetic variants (15 novel and 8 previously described), clustering into five phylogroups. Three phylogroups were associated with Bartonella vinsonii subsp. vinsonii, B. vinsonii subsp. arupensis, and B. washoensis, respectively. The other two phylogroups were not genetically related to any known Bartonella species. The genetic variants and phylogenetic groups exhibited a high degree of host specificity, mainly at the genus and family levels. This is the first study that describes the genetic diversity of Bartonella strains in wild rodents from Mexico. Considering that some variants found in this study are associated with Bartonella species that have been reported as zoonotic, more investigations are needed to further understand the ecology of Bartonella species in Mexican wildlife and their implications for human health.

  2. An Update of Sea Level Rise in the northwestern part of the Arabian Gulf

    Science.gov (United States)

    Alothman, Abdulaziz; Bos, Machiel; Fernandes, Rui

    2017-04-01

    Relative sea level variations in the northwestern part of the Arabian Gulf have been estimated in the past using no more than 10 to 15 years of observations. In Alothman et al. (2014), we have almost doubled the period to 28.7 years by examining all available tide gauge data in the area and constructing a mean gauge time-series from seven coastal tide gauges. We found for the period 1979-2007 a relative sea level rise of about 2mm/yr, which correspond to an absolute sea level rise of about 1.5mm/yr based on the vertical displacement of GNSS stations in the region. By taking into account the temporal correlations we concluded that previous published results underestimate the true sea level rate error in this area by a factor of 5-10. In this work, we discuss and update the methodology and results from Alothman et al. (2014), particularly by checking and extending the GNSS solutions. Since 3 of the 6 GPS stations used only started observing in the end of 2011, the longer time series have now significantly lower uncertainties in the estimated vertical rate. In addition, we compare our results with GRACE derived ocean bottom pressure time series which are a good proxy of the changes in water mass in this area over time.

  3. Trawling disturbance on benthic ecosystems and consequences on commercial species: a northwestern Mediterranean case study

    Directory of Open Access Journals (Sweden)

    Alba Muntadas

    2014-03-01

    Full Text Available Trawling is known to disturb benthic communities and habitats, which may in turn indirectly affect populations of commercial species that live in close association with the seabed. The degree of impact on both benthic communities and demersal species depends on the fishing effort level. This may vary over the year because of the fleet dynamics, which are in turn normally driven by the main target species’ life cycle. In this study we describe changes in benthic functional components of a northwestern Mediterranean fishing ground that represents a recruitment area for an important target species (red mullet, Mullus barbatus. This fishing ground experiences a varying intensity of fishing effort over the year and benthic functional components under different levels of trawling were compared with an unfished, control area. Traits related to sexual maturity and life span for infauna and body size and life span for epifauna were found to vary with fishing activity. Potential effects of these changes on ecological functioning and the impact on red mullet population are discussed. The development of fisheries management plans under an ecosystem based fisheries management (EBFM requires the links between target species and benthic communities’ disturbance due to fishing practices to be explicitly considered.

  4. Variability of Solar Radiation and CDOM in Surface Coastal Waters of the Northwestern Mediterranean Sea.

    Science.gov (United States)

    Sempéré, Richard; Para, Julien; Tedetti, Marc; Charrière, Bruno; Mallet, Marc

    2015-01-01

    Atmospheric and in-water solar radiation, including UVR-B, UVR-A and PAR, as well as chromophoric dissolved organic matter absorption [aCDOM (λ)] in surface waters were monthly measured from November 2007 to December 2008 at a coastal station in the Northwestern Mediterranean Sea (Bay of Marseilles, France). Our results showed that the UVR-B/UVR-A ratio followed the same trend in the atmosphere and at 2 m depth in the water (P CDOM contributed to UVR attenuation in the UVA domain, but also played a significant role in PAR attenuation. Mean UV doses received in the mixed layer depth were higher by a factor 1.4-33 relative to doses received at fixed depths (5 and 10 m) in summer (stratified period), while the inverse pattern was found in winter (mixing period). This shows the importance of taking into account the vertical mixing in the evaluation of UVR effects on marine organisms. © 2015 The American Society of Photobiology.

  5. Regional-scale drivers of forest structure and function in northwestern Amazonia.

    Directory of Open Access Journals (Sweden)

    Mark A Higgins

    Full Text Available Field studies in Amazonia have found a relationship at continental scales between soil fertility and broad trends in forest structure and function. Little is known at regional scales, however, about how discrete patterns in forest structure or functional attributes map onto underlying edaphic or geological patterns. We collected airborne LiDAR (Light Detection and Ranging data and VSWIR (Visible to Shortwave Infrared imaging spectroscopy measurements over 600 km2 of northwestern Amazonian lowland forests. We also established 83 inventories of plant species composition and soil properties, distributed between two widespread geological formations. Using these data, we mapped forest structure and canopy reflectance, and compared them to patterns in plant species composition, soils, and underlying geology. We found that variations in soils and species composition explained up to 70% of variation in canopy height, and corresponded to profound changes in forest vertical profiles. We further found that soils and plant species composition explained more than 90% of the variation in canopy reflectance as measured by imaging spectroscopy, indicating edaphic and compositional control of canopy chemical properties. We last found that soils explained between 30% and 70% of the variation in gap frequency in these forests, depending on the height threshold used to define gaps. Our findings indicate that a relatively small number of edaphic and compositional variables, corresponding to underlying geology, may be responsible for variations in canopy structure and chemistry over large expanses of Amazonian forest.

  6. Faunistic assemblages of a sublittoral coarse sand habitat of the northwestern Mediterranean

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    Eva Pubill

    2011-02-01

    Full Text Available The sublittoral megabenthic assemblages of a northwestern Mediterranean coarse sandy beach exploited for the bivalve Callista chione were studied. The spatial and bathymetric variability of its distinctive faunal assemblages was characterised by quantitative sampling performed with a clam dredge. The taxa studied were Mollusca Bivalvia and Gastropoda, Crustacea Decapoda, Echinodermata and Pisces, which accounted for over 99% of the total biomass. Three well-differentiated species assemblages were identified: (1 assemblage MSS (Medium Sand Shallow in medium sand (D50=0.37 mm and shallow waters (mean depth =6.5 m, (2 assemblage CSS (Coarse Sand Shallow in coarse sand (D50=0.62 mm in shallow waters (mean depth =6.7 m, and (3 assemblage CSD (Coarse Sand Deep in coarse sand (D50=0.64 mm in deeper waters (mean depth =16.2 m. Assemblage MSS was characterised by the codominance of the bivalves Mactra stultorum and Acanthocardia tuberculata. C. chione was dominant in both density and biomass in assemblages CSS and CSD. The occurrence of the crab Thia scutellata also characterised assemblage CSS, whereas the occurrence of the sea urchin Echinocardium mediterraneum characterised assemblage CSD. A depth breaking point of around 10 m determined the discontinuity between assemblages CSS and CSD, which was related to the closure depth of the beaches in the study area. Species richness was highest in the coarse sand communities; however, Shannon-Wiener diversity and Pielou equitability indexes were higher in the shallow fine sand community.

  7. Analysis of uranium, thorium, and potassium in the soil and rocks in northwestern Taiwan

    International Nuclear Information System (INIS)

    Shyong, J.; Wu, C.

    1984-01-01

    The contents of uranium, thorium, and potassium in terrestrial samples in northwestern Taiwan were determined by field survey and core sampling techniques. NaI(Tl) scintillation survey meters were applied to field survey. Analysis of radionuclides in the soil and rocks was performed by a 60 cm 3 Ge(Li) detector connected with a 4096-channel pulse height analyzer and a minicomputer PDP 11/04. Computer programs were used to identify energies of photopeaks, to integrate peak areas, and to evaluate the contents of radionuclides to ppm order. All the factors such as counting efficiency, statistical uncertainty, dead time, etc. had been taken into consideration. Natural terrestrial radiation exposure rates ranging from 6.5 to 20.5 uR.hr -1 were observed in 65 villages or hamlets. The average concentration of each of uranium, thorium, and potassium was 3.7+.0.8 ppm, 12.0+.2.8 ppm, and 1.3+.0.5 percent respectively

  8. Xenarthra (Mammalia) from a new late Neogene fossiliferous locality in Northwestern Argentina

    Science.gov (United States)

    Zurita, Alfredo E.; Camacho, María; Miño-Boilini, Angel R.; Candela, Adriana M.; Cuadrelli, Francisco; Krmpotic, Cecilia M.; Solís, Natalia

    2017-12-01

    Northwestern Argentina contains one of the most complete continental late Neogene (ca. 9-2.58 Ma) fossiliferous sequences in South America, especially in the current territories of the Catamarca, Tucumán and Jujuy provinces. More precisely in Jujuy Province several localities bearing mainly fossil mammals have been reported at the Quebrada de Humahuaca in the Uquía, Maimará and Tilcara formations, in which the clade Xenarthra (Mammalia) is well-represented. In this scenario, the fossiliferous potential of other localities of Jujuy Province are less known, especially in those areas located at the northwest end of Argentina, bordering Bolivia in the Northern Puna. A new late Neogene fossiliferous locality near Calahoyo (3639 m.a.s.l), Jujuy Province, is here reported. The materials, belonging to Xenarthra, were exhumed from the base of the Tafna Formation which was deposited in a sedimentary basin by alluvial and/or fluvial currents, undergoing transitions of various lacustrine episodes. The taxa include the Tardigrada Pyramiodontherium bergi (Megatheriidae) and the Cingulata Eosclerocalyptus sp. (Glyptodontidae) and Macrochorobates chapalmalensis (Dasypodidae). From a biostratigraphic viewpoint, this assemblage suggests a Late Miocene-Pliocene age for the base of the Tafna Formation, and partially contradicts the supposed Plio-Pleistocene age of this unit. Finally, the new specimens here described indicate that Xenarthra were taxonomically and ecologically diverse during the late Neogene in the northwest end of Argentina, since they are represented by at least three main lineages (sloths, glyptodontids and armadillos).

  9. Preliminary analysis of Greater Sage-grouse reproduction in the Virginia Mountains of northwestern Nevada

    Science.gov (United States)

    Coates, Peter S.; Lockyer, Zachary B.; Farinha, Melissa A.; Sweeney, Joelle M.; Johnson, Valerie M.; Meshriy, Matthew G.; Espinosa, Shawn P.; Delehanty, David J.; Casazza, Michael L.

    2011-01-01

    Relationships between habitat selection and population vital rates of greater sage-grouse (Centrocercus urophasianus; hereafter sage-grouse), recently designated as a candidate species under the Endangered Species Act, within the Great Basin are not well-understood. The growing development of renewable energy infrastructure within areas inhabited by sage-grouse is thought to influence predator and vegetation communities. For example, common ravens (Corvus corax), a synanthropic sage-grouse nest predator, are increasing range-wide and select transmission lines and other tall structures for nesting and perching. In the Virginia Mountains of northwestern Nevada, we collected preliminary information of space-use, habitat selection, and population vital rates during the nesting and brood-rearing period over two years on 56 sage-grouse. Additionally, videography at nest sites (n = 22) was used to identify sage-grouse nest predators. The study area is a potential site for renewable energy developments (i.e., wind and solar), and we plan to continue monitoring this population using a before-after-control-impact study design. The results reported here are preliminary and further data are required before conclusions can be drawn from this population of sage-grouse.

  10. Health Care Seeking Behavior among Caregivers of Sick Children Who Had Cerebral Malaria in Northwestern Nigeria

    Directory of Open Access Journals (Sweden)

    Edwin E. Eseigbe

    2012-01-01

    Full Text Available Cerebral malaria is a significant cause of childhood morbidity in our region. The challenges of effective management include time and quality of treatment. The study appraised the health care seeking behavior of caregivers of sick children who developed cerebral malaria, in Zaria, northwestern Nigeria. Caregivers indentified were parents 29 (87.9% and grandparents 4 (12.1%. Most of them were in the upper social classes. Health care options utilized before presentation at our facility were formal health facility 24 (72.7%, patent medicine seller 12 (36.4%, home treatment 10 (30.3%, and herbal concoction 6 (18.2% with majority 24 (72.7% using more than one option. Antimalarial therapy was instituted in 25 (75.6% of the cases. Mortality was significantly associated with the use of herbal concoction, treatment at a formal health facility and patent medicine seller, multiple convulsions, age less than 5 years, and noninstitution of antimalarial therapy before presentation. The study showed use of inappropriate health care options by caregivers and highlighted the need to pursue an awareness drive among caregivers on the use of health care options.

  11. Natural Intestinal Protozoa in Rodents (Rodentia: Gerbillinae, Murinae, Cricetinae in Northwestern Iran

    Directory of Open Access Journals (Sweden)

    Mehdi MOHEBALI

    2017-09-01

    Full Text Available Background: Majority of parasitic infections in rodents have zoonotic importance. This study aimed to determine the frequency and intensity of intestinal protozoa infections of rodents including Meriones persicus, Mus musculus and, Cricetulus migratorius.Methods: This survey was conducted in Meshkin Shahr district in northwestern Iran from Mar. to Dec. of 2014. Intestinal samples of 204 rodents including M. persicus (n=117, M. musculus (n=63 and C. migratorius (n=24 were parasitologically examined. Formalin-ether concentration method was done for all of rodents stool samples and observed with light microscope. All of suspected cases were stained with trichorome staining Method. Cultivation in dichromate potassium 2.5% was carried out for all of coccidian positive samples. Acid fast and aniline blue staining methods were used for detecting of coccidian oocysts and intestinal microsporidial spores, respectively.Results: About 121(59.3% of the caught rodents were generally infected with intestinal protozoa. Entamoeba muris 14(6.9%, Trichomonas muris 55(27.0%, Chilomastix betencourtti 17 (8.3%, Giardia muris 19(9.3%, Eimeria spp. 46(22.5%, Isospora spp. 4(2% and Cryptosporidium spp. 1(0.5% were found from the collected rodents. Microsporidian spores were identified in 63 (31% out of the 204 collected rodents using aniline blue staining method.Conclusion: Since some of the infections are zoonotic importance thus, control of rodents can be decreased new cases of the parasitic zoonoses in humans.

  12. Correlations between environmental factors and wild bee behavior on alfalfa (Medicago sativa) in northwestern China.

    Science.gov (United States)

    Wang, Xiaojuan; Liu, Hongping; Li, Xiaoxia; Song, Yu; Chen, Li; Jin, Liang

    2009-10-01

    To discover the effect of environmental factors on pollinator visitation to flowering Medicago sativa, several field experiments were designed to examine the diurnal movement patterns of wild bee species in the Hexi Corridor of northwestern China. Our study results showed that Megachile abluta, M. spissula, and Xylocopa valga showed unimodal diurnal foraging behavior, whereas Andrena parvula and Anthophora melanognatha showed bimodal diurnal foraging behavior. Correlation analysis indicated that diurnal foraging activities of pollinators were significantly correlated with environmental factors. Correlations of foraging activities versus environmental factors for M. abluta, M. spissula, and X. valga best fit a linear model, whereas those of A. parvula and A. melanognatha best fit a parallel quadratic model. Results of this study indicated that solitary wild bees such as M. abluta, M. spissula, X. valga, A. parvula, and A. melanognatha are potential alfalfa pollinators in the Hexi Corridor. An understanding of the environmental factors that affect the behaviors of different wild bees foraging in alfalfa are basic to the utilization of solitary wild bees in a practical way for increased, or more consistent, pollination of alfalfa for seed production.

  13. Structures and Evolutions of Explosive Cyclones over the Northwestern and Northeastern Pacific

    Science.gov (United States)

    Zhang, Shuqin; Fu, Gang

    2018-06-01

    In this study, the structures and evolutions of moderate (MO) explosive cyclones (ECs) over the Northwestern Pacific (NWP) and Northeastern Pacific (NEP) are investigated and compared using composite analysis with cyclone-relative coordinates. Final Operational Global Analysis data gathered during the cold seasons (October-April) of the 15 years from 2000 to 2015 are used. The results indicate that MO NWP ECs have strong baroclinicity and abundant latent heat release at low levels and strong upper-level forcing, which favors explosive cyclogenesis. The rapid development of MO NEP ECs results from their interaction with a northern cyclone and a large middle-level advection of cyclonic vorticity. The structural differences between MO NWP ECs and MO NEP ECs are significant. This results from their specific large-scale atmospheric and oceanic environments. MO NWP ECs usually develop rapidly in the east and southeast of the Japan Islands; the intrusion of cold dry air from the East Asian continent leads to strong baroclinicity, and the Kuroshio/Kuroshio Extension provides abundant latent heat release at low levels. The East Asian subtropical westerly jet stream supplies strong upper-level forcing. While MO NEP ECs mainly occur over the NEP, the low-level baroclinicity, upper-level jet stream, and warm ocean currents are relatively weaker. The merged cyclone associated with a strong middle-level trough transports large cyclonic vorticity to MO NEP ECs, which favors their rapid development.

  14. Natural Intestinal Protozoa in Rodents (Rodentia: Gerbillinae, Murinae, Cricetinae) in Northwestern Iran

    Science.gov (United States)

    MOHEBALI, Mehdi; ZAREI, Zabiholah; Khanaliha, Khadijeh; KIA, Eshrat Beigom; MOTAVALLI-HAGHI, Afsaneh; DAVOODI, Jaber; REZAEIAN, Tahereh; TARIGHI, Fathemeh; REZAEIAN, Mostafa

    2017-01-01

    Background: Majority of parasitic infections in rodents have zoonotic importance. This study aimed to determine the frequency and intensity of intestinal protozoa infections of rodents including Meriones persicus, Mus musculus and, Cricetulus migratorius. Methods: This survey was conducted in Meshkin Shahr district in northwestern Iran from Mar. to Dec. of 2014. Intestinal samples of 204 rodents including M. persicus (n=117), M. musculus (n=63) and C. migratorius (n=24) were parasitologically examined. Formalin-ether concentration method was done for all of rodents stool samples and observed with light microscope. All of suspected cases were stained with trichorome staining Method. Cultivation in dichromate potassium 2.5% was carried out for all of coccidian positive samples. Acid fast and aniline blue staining methods were used for detecting of coccidian oocysts and intestinal microsporidial spores, respectively. Results: About 121(59.3%) of the caught rodents were generally infected with intestinal protozoa. Entamoeba muris 14(6.9%), Trichomonas muris 55(27.0%), Chilomastix betencourtti 17 (8.3%), Giardia muris 19(9.3%), Eimeria spp. 46(22.5%), Isospora spp. 4(2%) and Cryptosporidium spp. 1(0.5%) were found from the collected rodents. Microsporidian spores were identified in 63 (31%) out of the 204 collected rodents using aniline blue staining method. Conclusion: Since some of the infections are zoonotic importance thus, control of rodents can be decreased new cases of the parasitic zoonoses in humans. PMID:28979348

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

    International Nuclear Information System (INIS)

    Zehner, H.H.

    1985-01-01

    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 its construction in 1940. The mean concentrations of uranium, Ra-226, and other trace elements generally were less than permissible limits established in national drinking water regulations or New Mexico State groundwater regulations. No individual surface water samples collected upstream from the mine contained concentrations of Ra-226 in excess of the permissible limits. Ra-226 concentrations in many individual samples collected from the Rio Paguate from near the mouth of the Rio Moquino to the sampling sites along the down-stream reach of the Rio Paguate, however, exceeded the recommended permissible concentration of Ra-226 for public drinking water supplies. After reclamation, most of the shallow groundwater probably will discharge to the natural stream channels draining the mine area. Groundwater quality may be monitored as: (1) Limited monitoring, in which only the change in water quality is determined as the groundwater flows from the mine; or (2) thorough monitoring, in which specific sources of possible contaminants are described

  16. Guineaworm infection in the Wa district of north-western Ghana.

    Science.gov (United States)

    Lyons, G R

    1972-01-01

    The Ghana-5 schistosomiasis project is situated in an exclusively rural area of north-western Ghana. Since the inhabitants rely for the most part on natural sources of drinking water the transmission of both urinary schistosomiasis and guineaworm infection must often occur at the same sites, and the epidemiology and the problems of control of these diseases might be expected to have features in common. An epidemiological survey of 8 300 people in 1967-68 showed that guineaworm had a scattered distribution, 35 of 43 villages having an annual incidence of less than 10%. Intensive study of 5 of the most seriously affected villages over a period of 3 years has shown that there is a delicate balance between the parasite and its human host in this area, largely as a result of the impermanent nature of the principal transmission sites, i.e., ponds and the smaller riverine pools. The timing, duration, and intensity of transmission have been shown to vary widely from one locality to another, as well as from year to year. These characteristics are determined by the type and extent of the local source of drinking water, the availability of alternative sources, and the monthly pattern of rainfall.

  17. Diets of swift foxes (Vulpes velox) in continuous and fragmented prairie in Northwestern Texas

    Science.gov (United States)

    Kamler, J.F.; Ballard, W.B.; Wallace, M.C.; Gipson, P.S.

    2007-01-01

    Distribution of the swift fox (Vulpes velox) has declined dramatically since the 1800s, and suggested causes of this decline are habitat fragmentation and transformation due to agricultural expansion. However, impacts of fragmentation and human-altered habitats on swift foxes still are not well understood. To better understand what effects these factors have on diets of swift foxes, scats were collected in northwestern Texas at two study sites, one of continuous native prairie and one representing fragmented native prairie interspersed with agricultural and fields in the Conservation Reserve Program. Leporids, a potential food source, were surveyed seasonally on both sites. Diets of swift foxes differed between sites; insects were consumed more on continuous prairie, whereas mammals, birds, and crops were consumed more on fragmented prairie. Size of populations of leporids were 2-3 times higher on fragmented prairie, and swift foxes responded by consuming more leporids on fragmented (11.1% frequency occurrence) than continuous (3.8%) prairie. Dietary diversity was greater on fragmented prairie during both years of the study. Differences in diets between sites suggested that the swift fox is an adaptable and opportunistic feeder, able to exploit a variety of food resources, probably in relation to availability of food. We suggest that compared to continuous native prairie, fragmented prairie can offer swift foxes a more diverse prey base, at least within the mosaic of native prairie, agricultural, and fields that are in the Conservation Reserve Program.

  18. Den site activity patterns of adult male and female swift foxes, Vulpes velox, in Northwestern Texas

    Science.gov (United States)

    Lemons, P.R.; Ballard, W.B.; Sullivan, R.M.; Sovada, M.A.

    2003-01-01

    Activity of Swift Foxes (Vulpes velox) at den sites was studied in northwestern Texas during pup rearing seasons in 2000 and 2001 to determine role of males in parental care. Twenty-four percent of radio-collared females with a potential to breed successfully raised pups to eight weeks of age. We intensively monitored presence and absence of male and female Swift Foxes at two den sites each year. Females were present >2.6 times more at den sites than males during the pup rearing season. Female and male Swift Foxes largely stayed at dens during diurnal hours and were active away from dens during nocturnal and crepuscular hours. Females and males spent 12.4% and 3.0% more time at dens before pups emerged, than after pups emerged, respectively. Following depredation of one male parent, the female spent 29% less time at the den site. Decrease in time spent at the den by the female following loss of her mate suggested that loss of one parent might severely impact recruitment of Swift Foxes. Our observations indicated that intense Coyote (Canis latrans) depredation may severely impact pup-rearing success as well as the parental care within Swift Fox family groups.

  19. Urban floods: a case study in the Savigliano area (North-Western Italy

    Directory of Open Access Journals (Sweden)

    C. Audisio

    2011-11-01

    Full Text Available Flood processes and effects are examined, concerning two rivers in an urbanized area in North-Western Italy (Piedmont – Cuneo Plain. In May 2008, some areas in Northern Italy were struck by intense and persistent rainfall. In the Cuneo province (Southern Piedmont, floodplain with some urban areas was inundated over ca. ten square kilometres, and the city of Savigliano (about 21 000 inhabitants was particularly hit by flood. A purposely-made historical research has evidenced approximately fifty flood events as having occurred since 1350 in the Savigliano area. Based upon historical data, both documents and maps, GIS (Geographical Information System technique and field surveys were used to quantitatively assess the growing urbanization of the city and to describe flood processes and effects over years. This work aims to describe the dynamic behaviour of the 2008 flood, also comparing it to past events, in particular those that occurred in 1896. It is emphasized how the knowledge of past events can be helpful in reducing urban flooding.

  20. Spatial structure and distribution of small pelagic fish in the northwestern Mediterranean Sea.

    Science.gov (United States)

    Saraux, Claire; Fromentin, Jean-Marc; Bigot, Jean-Louis; Bourdeix, Jean-Hervé; Morfin, Marie; Roos, David; Van Beveren, Elisabeth; Bez, Nicolas

    2014-01-01

    Understanding the ecological and anthropogenic drivers of population dynamics requires detailed studies on habitat selection and spatial distribution. Although small pelagic fish aggregate in large shoals and usually exhibit important spatial structure, their dynamics in time and space remain unpredictable and challenging. In the Gulf of Lions (north-western Mediterranean), sardine and anchovy biomasses have declined over the past 5 years causing an important fishery crisis while sprat abundance rose. Applying geostatistical tools on scientific acoustic surveys conducted in the Gulf of Lions, we investigated anchovy, sardine and sprat spatial distributions and structures over 10 years. Our results show that sardines and sprats were more coastal than anchovies. The spatial structure of the three species was fairly stable over time according to variogram outputs, while year-to-year variations in kriged maps highlighted substantial changes in their location. Support for the McCall's basin hypothesis (covariation of both population density and presence area with biomass) was found only in sprats, the most variable of the three species. An innovative method to investigate species collocation at different scales revealed that globally the three species strongly overlap. Although species often co-occurred in terms of presence/absence, their biomass density differed at local scale, suggesting potential interspecific avoidance or different sensitivity to local environmental characteristics. Persistent favourable areas were finally detected, but their environmental characteristics remain to be determined.

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

    International Nuclear Information System (INIS)

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

    2014-01-01

    Highlights: • Contamination of the ecosystem components by the radioactive isotopes 137 Cs, 90 Sr, 239, 240 Pu. • The maps of the temporal–spatial change in distribution of isotopes are submitted. • Zones with an increased ability to accumulate these radioactive pollutants were revealed. • Estimations of the flows of elimination of the radionuclides into the bottom sediments were carried out. • Assessment of dose rates formed by 90 Sr, 137 Cs and 239,240 Pu for Black Sea hydrobionts was obtained. - Abstract: 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

  2. Evaluation of trends in high temperature extremes in north-western Europe in regional climate models

    International Nuclear Information System (INIS)

    Min, E; Hazeleger, W; Van Oldenborgh, G J; Sterl, A

    2013-01-01

    Projections of future changes in weather extremes on the regional and local scale depend on a realistic representation of trends in extremes in regional climate models (RCMs). We have tested this assumption for moderate high temperature extremes (the annual maximum of the daily maximum 2 m temperature, T ann.max ). Linear trends in T ann.max from historical runs of 14 RCMs driven by atmospheric reanalysis data are compared with trends in gridded station data. The ensemble of RCMs significantly underestimates the observed trends over most of the north-western European land surface. Individual models do not fare much better, with even the best performing models underestimating observed trends over large areas. We argue that the inability of RCMs to reproduce observed trends is probably not due to errors in large-scale circulation. There is also no significant correlation between the RCM T ann.max trends and trends in radiation or Bowen ratio. We conclude that care should be taken when using RCM data for adaptation decisions. (letter)

  3. Impacts of Biomass Burning on Organic Aerosols over the Northwestern Pacific Ocean

    Science.gov (United States)

    Guo, T.; Guo, Z.

    2017-12-01

    During the cruise from East China Sea to Northwestern Pacific in March-April 2014, total suspended particle samples were collected and analyzed for tracers of primary and secondary organic aerosols (SOA) as well as OC and EC. In the study, the sum of all tracers during the sampling period ranged from 3.60 to 181.58 ng/m3, with a mean being 59.87±62.70 ng/m3. Among these tracers, glucose was the dominant compound (average: 17.73±20.60 ng/m3), followed by levoglucosan (12.82±14.37 ng/m3) and fructose (10.47±13.28 ng/m3). LEVO in samples affected by long range transport of biomass burning aerosol (17.38±21.32ng/m3) was about 1 order magnitude higher than the other (1.76±0.92ng/m3, pBTs. Thus organic aerosols over NWPO were deeply influenced by forest fires taking place in Siberia and North China as a result of long-range transport of both directly emitted OA and secondarily formed OA under high-NOx conditions during fire events.

  4. A mineralogical investigation of a uranium-bearing phosphatic siltstone from Tsongnapan, Northwestern Cape Province

    International Nuclear Information System (INIS)

    Brynard, H.J.

    1980-02-01

    A sample of uranium-bearing phosphatic siltstone from Tsongnapan in the Northwestern Cape Province was investigated mineralogically. The siltstone consists of cyclically alternating apatite- and calcite spherulite-rich layers. The calcite content of the rock is 11,4% and the apatite content is 42,1%. The groundmass shows the presence of the following elements: Si, Ca, P, Fe, Mg, K, Al, Cu and Zn. Detrital quartz, albite and magnetite are mainly confined to calcite spherulitic layers. The uranium content of the siltstone is 1 120 ppm U 3 O 8 and the thorium content 638 ppm ThO 2 . Both uranium and thorium occur mainly in the apatite-rich groundmass and to a minor extent in subsidiary monazite and zircon. Laboratory-scale metallurgical tests showed that the uranium is almost wholly leachable by hydrochloric acid while sulphuric and acetic acid dissolve only a small percentage of the uranium with concomitant formation of calcium sulphate. The rock probably formed in a low-energy regime in a marine environment where apatite and calcite spherulites crystallised from a possibly colloidal state [af

  5. Knowledge and attitude towards organ donation of medicine students of a Northwestern Mexico public university

    Science.gov (United States)

    Sebastián-Ruiz, María José; Guerra-Sáenz, Elda Karina; Vargas-Yamanaka, Anna Karen; Barboza-Quintana, Oralia; Ríos-Zambudio, Antonio; García-Cabello, Ricardo; Palacios-Saucedo, Gerardo Del Carmen

    2017-01-01

    To evaluate the knowledge and attitude towards organ donation of medicine students of a Northwestern Mexico public university. A prolective, descriptive, observational, and cross-sectional study. A 34 items cross-sectional survey evaluating knowledge and attitude towards organ donation in 3,056 medicine students during 2013-2015. Descriptive statistics were used as absolute frequencies, percentages, mean and standard deviation, as well as the Chi-square test. A p donate their own organs, mainly due to reciprocity (41%). 26% of students would not donate, 48% of them because of fear that their organs could be taken before death. 86% would donate organs from a relative. 64% have spoken about organ donation and transplantation with their family and 67% with friends. 50% said they had received no information about it. 68% understand the concept of brain death. Students received little information about organ donation during college. Despite that, most of them showed a positive attitude and are willing to donate. Copyright: © 2017 SecretarÍa de Salud

  6. Groundwater Diffuse Recharge and its Response to Climate Changes in Semi-Arid Northwestern China

    Directory of Open Access Journals (Sweden)

    Lin Deng

    2015-01-01

    Full Text Available Understanding the processes and rates of groundwater recharge in arid and semi-arid areas is crucial for utilizing and managing groundwater resources sustainably. We obtained three chloride profiles of the unsaturated-zone in the desert/loess transition zone of northwestern China and reconstructed the groundwater recharge variations over the last 11, 21, and 37 years, respectively, using the generalized chloride mass balance (GCMB method. The average recharge rates were 43.7, 43.5, and 45.1 mm yr-1, respectively, which are similar to those evaluated by the chloride mass balance (CMB or GCMB methods in other semi-arid regions. The results indicate that the annual recharge rates were not in complete linear proportion to the corresponding annual precipitations, although both exhibited descending tendencies on the whole. Comparisons between the daily precipitation aggregate at different intensity and recharge rates reveal that the occurrence of relatively heavy daily precipitation per year may contribute to such nonlinearity between annual precipitation and recharge. The possible influences of vegetation cover alterations following precipitation change cannot be excluded as well. The approximately negative correlation between the average annual recharge and temperature suggests that changes in temperature have had significant influences on recharge.

  7. Analysis of the prescribed burning practice in the pine forest of northwestern Portugal.

    Science.gov (United States)

    Fernandes, P; Botelho, H

    2004-01-01

    The ignition of low-intensity fires in the dormant season in the pine stands of north-western Portugal seeks to reduce the existing fuel hazard without compromising site quality. The purpose of this study is to characterise this practice and assess its effectiveness, based on information resulting from the normal monitoring process at the management level, and using operational guidelines, fire behaviour models and a newly developed method to classify prescribed fire severity. Although the region's humid climate strongly constrains the activity of prescribed fire, 87% of the fires analysed were undertaken under acceptable meteorological and fuel moisture conditions. In fact, most operations achieved satisfactory results. On average, prescribed fire reduces by 96% the potential intensity of a wildfire occurring under extreme weather conditions, but 36% of the treated sites would still require heavy fire fighting resources to suppress such fire, and 17% would still carry it in the tree canopy. Only 10% of the prescribed burns have an excessive impact on trees or the forest floor, while 89% (normal fire weather) or 59% (extreme fire weather) comply with both ecological integrity maintenance and wildfire protection needs. Improved planning and monitoring procedures are recommended in order to overcome the current deficiencies.

  8. Lipid reserves of red mullet (Mullus barbatus during pre-spawning in the northwestern Mediterranean

    Directory of Open Access Journals (Sweden)

    Josep Lloret

    2007-06-01

    Full Text Available Lipid reserves are a particularly important attribute of fishes because they have a large influence on growth, reproduction and survival. This study analyses the lipid content of red mullet (Mullus barbatus pre-spawners in three different areas of the northwestern Mediterranean in relation to trawling activities and river runoff. The muscle lipid was considered as an indicator of the somatic condition of individuals whilst the gonad lipid was used as a proxy of the energy invested in reproduction. The results show that fish with the highest muscle lipid levels inhabited the area where fishing impact was lowest. Since the abundance and biomass of polychaetes, which represent the main food source for red mullet, were found to be lower in trawled zones than in unfished ones, we suggest that differences in the muscle lipid levels between areas might be attributed to variation in prey abundance in relation to fishing impact. However, no impact of river runoff on lipid reserves of red mullet was observed. The results also show that muscle and gonad lipid reserves are not related to each other during pre-spawning.

  9. Response of internal solitary waves to tropical storm Washi in the northwestern South China Sea

    Directory of Open Access Journals (Sweden)

    Z. H. Xu

    2011-11-01

    Full Text Available Based on in-situ time series data from an array of temperature sensors and an acoustic Doppler current profiler on the continental shelf of the northwestern South China Sea, a sequence of internal solitary waves (ISWs were observed during the passage of tropical storm Washi in the summer of 2005, which provided a unique opportunity to investigate the ISW response to the tropical cyclone. The passing tropical storm is found to play an important role in affecting the stratification structure of the water column, and consequently leading to significant variability in the propagating features of the ISWs, such as the polarity reversal and amplitude variations of the waves. The response of the ISWs to Washi can be divided into two stages, direct forcing by the strong wind (during the arrival of Washi and remote forcing via the near-inertial internal waves induced by the tropical storm (after the passage of Washi. The field observations as well as a theoretical analysis suggest that the variations of the ISWs closely coincide with the changing stratification structure and shear currents in accompanied by the typhoon wind and near-inertial waves. This study presents the first observations and analysis of the ISW response to the tropical cyclone in the South China Sea.

  10. Ecological Variability and Carbon Stock Estimates of Mangrove Ecosystems in Northwestern Madagascar

    Directory of Open Access Journals (Sweden)

    Trevor G. Jones

    2014-01-01

    Full Text Available Mangroves are found throughout the tropics, providing critical ecosystem goods and services to coastal communities and supporting rich biodiversity. Despite their value, world-wide, mangroves are being rapidly degraded and deforested. Madagascar contains approximately 2% of the world’s mangroves, >20% of which has been deforested since 1990 from increased extraction for charcoal and timber and conversion to small to large-scale agriculture and aquaculture. Loss is particularly prominent in the northwestern Ambaro and Ambanja bays. Here, we focus on Ambaro and Ambanja bays, presenting dynamics calculated using United States Geological Survey (USGS national-level mangrove maps and the first localized satellite imagery derived map of dominant land-cover types. The analysis of USGS data indicated a loss of 7659 ha (23.7% and a gain of 995 ha (3.1% from 1990–2010. Contemporary mapping results were 93.4% accurate overall (Kappa 0.9, with producer’s and user’s accuracies ≥85%. Classification results allowed partitioning mangroves in to ecologically meaningful, spectrally distinct strata, wherein field measurements facilitated estimating the first total carbon stocks for mangroves in Madagascar. Estimates suggest that higher stature closed-canopy mangroves have average total vegetation carbon values of 146.8 Mg/ha (±10.2 and soil organic carbon of 446.2 (±36.9, supporting a growing body of studies that mangroves are amongst the most carbon-dense tropical forests.

  11. Luminescence dating of the Zeketai loess section in the Ili Basin, northwestern China: Methodological considerations

    Science.gov (United States)

    Qin, Jintang; Zhou, Liping

    2018-04-01

    Loess deposits in Xinjiang, northwestern China are ideal archives for past environmental changes in the Westerlies-dominated central Asia. Among previous luminescence dating studies of loess in Xinjiang, few have attempted to systematically investigate the methodological aspects. In this study, we report results of a multiple-procedure luminescence dating of the Zeketai loess section in the Ili Basin, central Xinjiang. Optically stimulated luminescence (OSL) and post-infrared infrared stimulated luminescence (pIRIR) signals were used for quartz and polymineral grains of different sizes. The pIRIR ages obtained with two protocols agree well with each other and constrain the loess deposition between 50 ka and 88 ka. The OSL ages of fine-grained quartz are in stratigraphic order and range from 37 ka to 61 ka, but are ∼30% younger than the pIRIR295 ages of both fine and medium grained polyminerals. Although the causes of the discrepancy between the ages derived from different luminescence dating protocols are still to be understood, we stress that the quartz OSL ages of loess in this region are likely to be underestimated, especially for samples older than 40 ka. The polymineral or potassium feldspar pIRIR signal is recommended for dating loess in the Ili Basin, at least as an internal check.

  12. Coralline algal barium as indicator for 20th century northwestern North Atlantic surface ocean freshwater variability.

    Science.gov (United States)

    Hetzinger, S; Halfar, J; Zack, T; Mecking, J V; Kunz, B E; Jacob, D E; Adey, W H

    2013-01-01

    During the past decades climate and freshwater dynamics in the northwestern North Atlantic have undergone major changes. Large-scale freshening episodes, related to polar freshwater pulses, have had a strong influence on ocean variability in this climatically important region. However, little is known about variability before 1950, mainly due to the lack of long-term high-resolution marine proxy archives. Here we present the first multidecadal-length records of annually resolved Ba/Ca variations from Northwest Atlantic coralline algae. We observe positive relationships between algal Ba/Ca ratios from two Newfoundland sites and salinity observations back to 1950. Both records capture episodical multi-year freshening events during the 20th century. Variability in algal Ba/Ca is sensitive to freshwater-induced changes in upper ocean stratification, which affect the transport of cold, Ba-enriched deep waters onto the shelf (highly stratified equals less Ba/Ca). Algal Ba/Ca ratios therefore may serve as a new resource for reconstructing past surface ocean freshwater changes.

  13. Preliminary report on osteochondrosis in cattle in the north-western parts of South Africa

    Directory of Open Access Journals (Sweden)

    Leon Prozesky

    2016-07-01

    Full Text Available The north-western part of South Africa, in particular, is well known for mineral imbalances. Aphosphorosis, resulting in rickets and osteomalacia, received a lot of attention at the turn of the nineteenth century (1882–1912. This was followed in 1997 by research on Vryburg hepatosis, another area-specific mineral imbalance–related disease in young calves reared on manganese-rich soil derived from the weathering of dolomitic (carbonate rock formations. In 1982, a totally new syndrome (osteochondrosis manifested in, amongst others, areas in South Africa where aphosphorosis was rife. Osteochondrosis was also identified in the south-western parts of Namibia as well as southern Botswana and other areas in South Africa. Osteochondrosis has a multifactorial aetiology and this study focused on the role of minerals, particularly phosphorus, in the development of the disease. A significant improvement in the clinical signs in experimental animals and a reduction of osteochondrosis occurred on farms where animals received bioavailable trace minerals and phosphorus as part of a balanced lick. An increase in the occurrence of the disease on farms during severe drought conditions in 2012–2013 prompted researchers to investigate the possible role of chronic metabolic acidosis in the pathogenesis of the disease.

  14. Petrography and geochronology (U/Pb-Sm/Nd) the Passagem Granite, Pensamiento Granitoid Complex, Paragua Terrane, SW Amazon Craton, Mato Grosso, Brazil; Petrologia e geocronologia (U/Pb-Sm/Nd) do Granito Passagem, Complexo Granitoide Pensamiento, SW do Craton Amazonico (MT)

    Energy Technology Data Exchange (ETDEWEB)

    Jesus, Gisely Carmo de, E-mail: giselycarmo@hotmail.co [Universidade Federal de Mato Grosso (ICET/UFMT), Cuiaba, MT (Brazil). Inst. de Ciencias Exatas e da Terra. Programa de Pos-Graduacao em Geociencias; Sousa, Maria Zelia Aguiar de, E-mail: mzaguiar@terra.com.b [Universidade Federal de Mato Grosso(ICET/UFMT), Cuiaba, MT (Brazil). Inst. de Ciencias Exatas e da Terra. Dept. de Recursos Minerais; Ruiz, Amarildo Salina; Matos, Joao Batista de, E-mail: asruiz@gmail.co, E-mail: jmatos@cpd.ufmt.b [Universidade Federal de Mato Grosso (ICET/UFMT), Cuiaba, MT (Brazil). Inst. de Ciencias Exatas e da Terra. Dept. de Geologia Geral

    2010-09-15

    The Passagem granite includes stocks, plugs and dikes located in the Ricardo Franco hill - Vila Bela da Santissima Trindade region - state of Mato Grosso, central Brazil. The Passagem Granite is included in the Paragua terrane - SW Amazonian Craton. It consists of isotropic monzogranite, sienogranite and more rarely granodiorites with leucocratic dark gray to white color. These rocks range from hypidomorphic inequigranular to xenomorphic texture, fine to medium grained. Biotite is the only primary mafic present as essential phase and characterize an expanded slightly acid sequence formed by a sub-alkaline magmatism of high-potassium calc-alkaline, slightly peraluminous composition from arc magmatic tectonic environment during a post-collisional period. Mechanism of fractional crystallization of plagioclase, biotite, titanite, apatite and zircon associated with simultaneous crustal assimilation are suggested for the evolution of these rocks. The results support the hypothesis of a post-collisional magmatism in the Paragua terrane at 1284 +- 20 Ma corresponding to the crystallization age of the Passagem granite. This paper propose that Passagem Granite represents as an extension in Brazilian terrane of the Pensamiento Granitoid Complex. (author)

  15. Paleozoic evolution of active margin basins in the southern Central Andes (northwestern Argentina and northern Chile)

    Science.gov (United States)

    Bahlburg, H.; Breitkreuz, C.

    The geodynamic evolution of the Paleozoic continental margin of Gondwana in the region of the southern Central Andes is characterized by the westward progression of orogenic basin formation through time. The Ordovician basin in the northwest Argentinian Cordillera Oriental and Puna originated as an Early Ordovician back-arc basin. The contemporaneous magmatic arc of an east-dipping subduction zone was presumably located in northern Chile. In the back-arc basin, a ca. 3500 meter, fining-up volcaniclastic apron connected to the arc formed during the Arenigian. Increased subsidence in the late Arenigian allowed for the accomodation of large volumes of volcaniclastic turbidites during the Middle Ordovician. Subsidence and sedimentation were caused by the onset of collision between the para-autochthonous Arequipa Massif Terrane (AMT) and the South American margin at the Arenigian-Llanvirnian transition. This led to eastward thrusting of the arc complex over its back-arc basin and, consequently, to its transformation into a marine foreland basin. As a result of thrusting in the west, a flexural bulge formed in the east, leading to uplift and emergence of the Cordillera Oriental shelf during the Guandacol Event at the Arenigian-Llanvirnian transition. The basin fill was folded during the terminal collision of the AMT during the Oclóyic Orogeny (Ashgillian). The folded strata were intruded post-tectonically by the presumably Silurian granitoids of the "Faja Eruptiva de la Puna Oriental." The orogeny led to the formation of the positive area of the Arco Puneño. West of the Arco Puneño, a further marine basin developed during the Early Devonian, the eastern shelf of which occupied the area of the Cordillera Occidental, Depresión Preandina, and Precordillera. The corresponding deep marine turbidite basin was located in the region of the Cordillera de la Costa. Deposition continued until the basin fill was folded in the early Late Carboniferous Toco Orogeny. The basin

  16. Mercury in organisms from the Northwestern Mediterranean slope: Importance of food sources

    Energy Technology Data Exchange (ETDEWEB)

    Cresson, P., E-mail: pierre.cresson@ifremer.fr [Ifremer, Centre de Méditerranée, CS 20330, F-83 507 La Seyne-sur-Mer (France); Fabri, M.C., E-mail: marie.claire.fabri@ifremer.fr [Ifremer, Centre de Méditerranée, CS 20330, F-83 507 La Seyne-sur-Mer (France); Bouchoucha, M., E-mail: marc.bouchoucha@ifremer.fr [Ifremer, Centre de Méditerranée, CS 20330, F-83 507 La Seyne-sur-Mer (France); Brach Papa, C., E-mail: christophe.brach.papa@ifremer.fr [Ifremer, Centre Atlantique, BP 21105, F-44311 Nantes Cedex 03 (France); Chavanon, F., E-mail: fabienne.chavanon@ifremer.fr [Ifremer, Centre de Méditerranée, CS 20330, F-83 507 La Seyne-sur-Mer (France); Jadaud, A., E-mail: angelique.jadaud@ifremer.fr [Ifremer, Centre de Méditerranée, CS 30171, F-34203 Sète Cedex (France); Knoery, J., E-mail: joel.knoery@ifremer.fr [Ifremer, Centre Atlantique, BP 21105, F-44311 Nantes Cedex 03 (France); Miralles, F., E-mail: fmarco@ifremer.fr [Ifremer, Centre de Méditerranée, CS 20330, F-83 507 La Seyne-sur-Mer (France); Cossa, D., E-mail: daniel.cossa@ifremer.fr [Ifremer, Centre de Méditerranée, CS 20330, F-83 507 La Seyne-sur-Mer (France); IS Terre, Université Joseph Fourier, BP 53, F-38041 Grenoble (France)

    2014-11-01

    Mercury (Hg) is a global threat for marine ecosystems, especially within the Mediterranean Sea. The concern is higher for deep-sea organisms, as the Hg concentration in their tissues is commonly high. To assess the influence of food supply at two trophic levels, total Hg concentrations and carbon and nitrogen stable isotope ratios were determined in 7 species (4 teleosts, 2 sharks, and 1 crustacean) sampled on the upper part of the continental slope of the Gulf of Lions (Northwestern Mediterranean Sea), at depths between 284 and 816 m. Mean Hg concentrations ranged from 1.30 ± 0.61 to 7.13 ± 7.09 μg g{sup −1} dry mass, with maximum values observed for small-spotted catshark Scyliorhinus canicula. For all species except blue whiting Micromesistius poutassou, Hg concentrations were above the health safety limits for human consumption defined by the European Commission, with a variable proportion of the individuals exceeding limits (from 23% for the Norway lobster Nephrops norvegicus to 82% for the blackbelly rosefish Helicolenus dactylopterus). Measured concentrations increased with increasing trophic levels. Carbon isotopic ratios measured for these organisms demonstrated that settling phytoplanktonic organic matter is not only the main source fueling trophic webs but also the carrier of Hg to this habitat. Inter- and intraspecific variations of Hg concentrations revealed the importance of feeding patterns in Hg bioaccumulation. In addition, biological parameters, such as growth rate or bathymetric range explain the observed contamination trends. - Highlights: • Hg and stable isotope ratios were assessed in 7 species from Mediterranean slope. • Settling phytoplankton was the main OM and Hg source, as confirmed by δ{sup 13}C values. • All species except one exceeded Hg consumption limits. • Depth and diet were important factors explaining Hg content. • Results confirmed the concern about Hg in the deep Mediterranean.

  17. Mercury in organisms from the Northwestern Mediterranean slope: Importance of food sources

    International Nuclear Information System (INIS)

    Cresson, P.; Fabri, M.C.; Bouchoucha, M.; Brach Papa, C.; Chavanon, F.; Jadaud, A.; Knoery, J.; Miralles, F.; Cossa, D.

    2014-01-01

    Mercury (Hg) is a global threat for marine ecosystems, especially within the Mediterranean Sea. The concern is higher for deep-sea organisms, as the Hg concentration in their tissues is commonly high. To assess the influence of food supply at two trophic levels, total Hg concentrations and carbon and nitrogen stable isotope ratios were determined in 7 species (4 teleosts, 2 sharks, and 1 crustacean) sampled on the upper part of the continental slope of the Gulf of Lions (Northwestern Mediterranean Sea), at depths between 284 and 816 m. Mean Hg concentrations ranged from 1.30 ± 0.61 to 7.13 ± 7.09 μg g −1 dry mass, with maximum values observed for small-spotted catshark Scyliorhinus canicula. For all species except blue whiting Micromesistius poutassou, Hg concentrations were above the health safety limits for human consumption defined by the European Commission, with a variable proportion of the individuals exceeding limits (from 23% for the Norway lobster Nephrops norvegicus to 82% for the blackbelly rosefish Helicolenus dactylopterus). Measured concentrations increased with increasing trophic levels. Carbon isotopic ratios measured for these organisms demonstrated that settling phytoplanktonic organic matter is not only the main source fueling trophic webs but also the carrier of Hg to this habitat. Inter- and intraspecific variations of Hg concentrations revealed the importance of feeding patterns in Hg bioaccumulation. In addition, biological parameters, such as growth rate or bathymetric range explain the observed contamination trends. - Highlights: • Hg and stable isotope ratios were assessed in 7 species from Mediterranean slope. • Settling phytoplankton was the main OM and Hg source, as confirmed by δ 13 C values. • All species except one exceeded Hg consumption limits. • Depth and diet were important factors explaining Hg content. • Results confirmed the concern about Hg in the deep Mediterranean

  18. Morphology and genetics of Anadenanthera colubrina var. cebil (Fabaceae) tree from salta (Northwestern Argentina).

    Science.gov (United States)

    de Viana, Marta L; Giamminola, Eugenia; Russo, Roberta; Ciaccio, Mirella

    2014-06-01

    Anadenanthera colubrina var. cebil is an important tree species for its cultural, economic, and medicinal uses in South America. In order to characterize A. colubrina populations, we collected fruits from four different sites (San Bernardo, El Cebilar, Metán and El Gallinato) within the species distribution area in Salta Province, Northwestern Argentina. For this, a total of 75 fruits and seeds per site were collected and described using morphological (fruits size and weight; seed weight and number per fruit) and genetic descriptors (ribosomic DNA extraction and PCR; nucleotide alignment and phylogenetic analysis) with standard protocols. Our results showed that the San Bernardo population had the heaviest fruits and seeds (7.89 +/- 0.2g and 0.19 +/- 0.002, respectively), and the Cebilar population the lightest (6.25 +/- 0.18g and 0.15 +/- 0.002g, respectively). Fruits and seeds from Metán and El Gallinato showed similar and intermediate values. The proportion viable (39 to 55%) and aborted (43 to 57%) seeds was different, while the proportion of predated (1.7 to 4.2%) seeds was similar among populations. The genetic analysis showed variability of ITS sequences within the especies, and also when compared with the same Brazilian species. Both, morphologic and genetic descriptors showed a high level of similarity between San Bernardo and Metán, and between El Cebilar and El Gallinato populations. Further studies are needed to assess levels of phenotypic and genetic variability within and between populations of different plant species, since this information is crucial for biodiversity and germplasm long-term conservation.

  19. Simulation and analysis of the mesoscale circulation in the northwestern Mediterranean Sea

    Directory of Open Access Journals (Sweden)

    V. Echevin

    Full Text Available The large-scale and mesoscale circulation of the northwestern Mediterranean Sea are simulated with an eddy-resolving primitive-equation regional model (RM of 1/16° resolution embedded in a general circulation model (GM of the Mediterranean Sea of 1/8° resolution. The RM is forced by a monthly climatology of heat fluxes, precipitation and wind stress. The GM, which uses the same atmospheric forcing, provides initial and boundary conditions for the RM. Analysis of the RM results shows that several realistic features of the large-scale and mesoscale circulation are evident in this region. The mean cyclonic circulation is in good agreement with observations. Mesoscale variability is intense along the coasts of Sardinia and Corsica, in the Gulf of Lions and in the Catalan Sea. The length scales of the Northern Current meanders along the Provence coast and in the Gulf of Lions’ shelf are in good agreement with observations. Winter Intermediate Water is formed along most of the north-coast shelves, between the Gulf of Genoa and Cape Creus. Advection of this water by the mean cyclonic circulation generates a complex eddy field in the Catalan Sea. Intense anticyclonic eddies are generated northeast of the Balearic Islands. These results are in good agreement with mesoscale activity inferred from satellite altimetric data. This work demonstrates the feasibility of a down-scaling system composed of a general-circulation, a regional and a coastal model, which is one of the goals of the Mediterranean Forecasting System Pilot Project.

    Key words. Oceanography: physical (currents; eddies and mesoscale processes; general circulation

  20. The Sap Flow Dynamics and Response of Hedysarum scoparium to Environmental Factors in Semiarid Northwestern China.

    Directory of Open Access Journals (Sweden)

    Jifeng Deng

    Full Text Available Hedysarum scoparium is an important, fast-growing and drought-resistant shrub that has been extensively used for grassland restoration and preventing desertification in semiarid regions of northwestern China. The primary objective of this study was to investigate the diurnal and seasonal variations in stem sap flow (Js and its relation to environmental factors. The stem heat balance method was applied to plants that were approximately 17 years old (with diameters of 25, 16, 13, and 9 mm at ground level and heights of 3.1, 1.8, 1.7 and 1.4 m and growing under natural conditions. The vertical soil temperature profile (ST, soil surface heat flux (SoilG, volumetric soil moisture content (SWC and meteorological variables such as solar radiation (Rn, air temperature (Ta, vapour pressure deficit (VPD, wind speed (Ws relative humidity (RH and precipitation (P were simultaneously measured at a meteorological station on site. Results indicated that Js varied regularly during the diurnal and seasonal term. The nocturnal Js was substantial, with a seasonal variation similar to the patterns of daytime Js. The magnitude of Js changed considerably between sunny and rainy days. Redundancy (RDA and Kendall's tau analysis suggested that daily Js in large plants was more sensitive to environmental factors, and the variation in daily Js during the growing season could be described by a multiple linear regression against environmental variables including Ta, VPD, Ws, RH, ST, and SoilG. While the nocturnal Js in smaller plants was more sensitive to meteorological factors. Ta, VPD, and Ws were significantly correlated with nighttime Js. The hourly nighttime sap flow rate of H. scoparium corresponded closely to Ta and VPD following a non-linear pattern. The results of this study can be used to estimate the transpiration of H. scoparium.