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Sample records for basin northern guerrero

  1. FLORISTIC STUDY IN THE LOWER PAPAGAYO RIVER BASIN, GUERRERO, MEXICO

    OpenAIRE

    Blanca Estela Carreto-Pérez; Ángel Almazán-Juárez; Pablo Sierra-Morales; R. Carlos Almazán-Núñez

    2015-01-01

    We present the floristic composition of the Papagayo river basin, Guerrero, México.Field work was carried out from June 2011 to June 2012. We identified a total of 204 species of vascular plants, including 73 families and 163 genus. Families Fabaceae,Poaceae, Asteraceae, Euphorbiaceae and Rubiaceae represented 41% of all species and 38% of the genus in the study area. The herbaceous plant life form was the best represented with 81 species (40%). Were determined 10 vegetation types, of which t...

  2. FLORISTIC STUDY IN THE LOWER PAPAGAYO RIVER BASIN, GUERRERO, MEXICO

    Directory of Open Access Journals (Sweden)

    Blanca Estela Carreto-Pérez

    2015-11-01

    Full Text Available We present the floristic composition of the Papagayo river basin, Guerrero, México.Field work was carried out from June 2011 to June 2012. We identified a total of 204 species of vascular plants, including 73 families and 163 genus. Families Fabaceae,Poaceae, Asteraceae, Euphorbiaceae and Rubiaceae represented 41% of all species and 38% of the genus in the study area. The herbaceous plant life form was the best represented with 81 species (40%. Were determined 10 vegetation types, of which the tropical deciduous forest covers the largest area and has the richest flora. Eleven species were recorded under the category of threatened by NOM-059-SEMARNAT-2010, of which one is endemic to Mexico (Rhizophora mangle.

  3. Avifauna de la subcuenca del río San Juan, Guerrero, México Avifauna of the Río San Juan Basin, Guerrero, Mexico

    OpenAIRE

    R. Carlos Almazán-Núñez; Adolfo G. Navarro S.

    2006-01-01

    Se presenta un análisis de la riqueza avifaunística en diferentes tipos de vegetación en la subcuenca del río San Juan, perteneciente a la provincia biótica de la Cuenca del Balsas, Guerrero. El trabajo de campo se realizó de junio de 2001 a septiembre de 2002. La riqueza avifaunística en la zona fue de 164 especies considerando los registros previos. Se mencionan algunos registros de interés los cuales amplían su área de distribución geográfica dentro del estado. La riqueza de especies fue s...

  4. Ampliación de la distribución y presencia de una colonia reproductiva de la guacamaya verde (Ara militaris en el alto Balsas de Guerrero, México Range expansion and reproductive colony of the Military Macaw (Ara militaris in the upper Balsas basin, Guerrero, México

    Directory of Open Access Journals (Sweden)

    Víctor H. Jiménez-Arcos

    2012-09-01

    Full Text Available Se registra una población y colonia reproductora de guacamaya verde (Ara militaris en el alto Balsas de Guerrero. La colonia se ubica en el bosque tropical seco de la localidad de Papalutla, al margen del río Atoyac, en el extremo noreste del estado. A lo largo de 4 años de conteos (n= 20, se registró una abundancia de 22.7 ± 2.8 individuos. Este registro confirma que la guacamaya verde aún se reproduce en Guerrero y amplía en aproximadamente 100 km hacia el extremo noreste del estado su distribución conocida.We report a new population of green macaw (Ara militaris to the Mexican state of Guerrero. The colony is located besides the Atoyac River, in the dry tropical forest of Papalutla, in the far northeast corner of the state. Along 4 years of counts (n= 20, an abundance of 22.7 ± 2.8 individuals has been registered. This report is relevant because it is the first record of a resident colony of green macaw in the upper Balsas basin, extending its known distribution range to the northwestern limit of Guerrero.

  5. Megafans of the Northern Kalahari Basin

    Science.gov (United States)

    Wilkinson, M. J.; Miller, R. McG.; Eckardt, F.; Kreslavsky, M. A.

    2016-01-01

    We identify eleven megafans (partial cones of fluvial sediment, >80 km radius) in the northern Kalahari Basin, using several criteria based on VIS and IR remotely sensed data and SRTM-based surface morphology reconstructions. Two other features meet fewer criteria of the form which we class as possible megafans. The northern Kalahari megafans are located in a 1700 km arc around the southern and eastern flanks of the Angola's Bié Plateau, from northern Namibia through northwest Botswana to western Zambia. Three lie in the Owambo subbasin centered on the Etosha Pan, three in the relatively small Okavango rift depression, and five in the Upper Zambezi basin. The population includes the well-known Okavango megafan (150 km), Namibia's Cubango megafan, the largest megafan in the region (350 km long), and the largest nested group (the five major contiguous megafans on the west slopes of the upper Zambezi Valley). We use new, SRTM-based topographic roughness data to discriminate various depositional surfaces within the flat N. Kalahari landscapes. We introduce the concepts of divide megafans, derived megafans, and fan-margin rivers. Conclusions. (i) Eleven megafan cones total an area of 190,000 sq km. (ii) Different controls on megafan size operate in the three component basins: in the Okavango rift structural controls become the prime constraint on megafan length by controlling basin dimensions. Megafans in the other les constricted basins appear to conform to classic relationships fan area, slope, and feeder-basin area. (iii) Active fans occupy the Okavango rift depression with one in the Owambo basin. The rest of the population are relict but recently active fans (surfaces are relict with respect to activity by the feeder river). (iv) Avulsive behavior of the formative river-axiomatic for the evolution of megafans-has resulted in repeated rearrangements of regional drainage, with likely effects in the study area well back into the Neogene. Divide megafans comprise the

  6. Tlapaneco de Malinaltepec, Guerrero (Tlapanec of Malinaltepec, Guerrero).

    Science.gov (United States)

    Suarez, Jorge A.

    This document is one of 17 volumes on indigenous Mexican languages and is the result of a project undertaken by the Archivo de Lenguas Indigenas de Mexico. This volume contains information on Tlapanec, an indigenous language of Mexico spoken in Malinaltepec, in the state of Guerrero. The objective of collecting such a representative sampling of…

  7. Geothermal resources of the northern gulf of Mexico basin

    Science.gov (United States)

    Jones, P.H.

    1970-01-01

    Published geothermal gradient maps for the northern Gulf of Mexico basin indicate little or no potential for the development of geothermal resources. Results of deep drilling, from 4000 to 7000 meters or more, during the past decade however, define very sharp increases in geothermal gradient which are associated with the occurrence of abnormally high interstitial fluid pressure (geopressure). Bounded by regional growth faults along the landward margin of the Gulf Basin, the geopressured zone extends some 1300 km from the Rio Grande (at the boundary between the United States and Mexico) to the mouth of the Mississippi river. Gulfward, it extends to an unknown distance across the Continental Shelf. Within geopressured deposits, geothermal gradients range upwards to 100 ??C/km, being greatest within and immediately below the depth interval in which the maximum pressure gradient change occurs. The 120 ??C isogeotherm ranges from about 2500 to 5000 m below sea level, and conforms in a general way with depth of occurrence of the top of the geopressured zone. Measured geostatic ratios range upward to 0.97; the maximum observed temperature is 273 ??C, at a depth of 5859 m. Dehydration of montmorillonite, which comprises 60 to 80 percent of clay deposited in the northern Gulf Basin during the Neogene, occurs at depths where temperature exceeds about 80 ??C, and is generally complete at depths where temperature exceeds 120 ??C. This process converts intracrystalline and bound water to free pore water, the volume produced being roughly equivalent to half the volume of montmorillonite so altered. Produced water is fresh, and has low viscosity and density. Sand-bed aquifers of deltaic, longshore, or marine origin form excellent avenues for drainage of geopressured deposits by wells, each of which may yield 10,000 m3 or more of superheated water per day from reservoirs having pressures up to 1000 bars at depths greater than 5000 m. ?? 1971.

  8. Three-dimensional seismo-tectonics in the Po Valley basin, Northern Italy

    NARCIS (Netherlands)

    Turrini, Claudio; Angeloni, Pamela; Lacombe, Olivier; Ponton, Maurizio; Roure, François

    2015-01-01

    The Po Valley (Northern Italy) is a composite foreland-foredeep basin caught in between the Southern Alps and Northern Apennine mountain belts. By integrating the 3D structural model of the region with the public earthquake dataset, the seismo-tectonics of the basin is shown at different scales of o

  9. Cenozoic foreland-basin evolution in the northern Andes : insights from thermochronology and basin analysis in the Eastern Cordillera, Colombia

    OpenAIRE

    Parra, Mauricio

    2009-01-01

    The modern foreland basin straddling the eastern margin of the Andean orogen is the prime example of a retro-arc foreland basin system adjacent to a subduction orogen. While widely studied in the central and southern Andes, the spatial and temporal evolution of the Cenozoic foreland basin system in the northern Andes has received considerably less attention. This is in part due to the complex geodynamic boundary conditions, such as the oblique subduction and accretion of the Caribbean plates ...

  10. Regional Fluid Flow and Basin Modeling in Northern Alaska

    Science.gov (United States)

    Kelley, Karen D.

    2007-01-01

    INTRODUCTION The foothills of the Brooks Range contain an enormous accumulation of zinc (Zn) in the form of zinc sulfide and barium (Ba) in the form of barite in Carboniferous shale, chert, and mudstone. Most of the resources and reserves of Zn occur in the Red Dog deposit and others in the Red Dog district; these resources and reserves surpass those of most deposits worldwide in terms of size and grade. In addition to zinc and lead sulfides (which contain silver, Ag) and barite, correlative strata host phosphate deposits. Furthermore, prolific hydrocarbon source rocks of Carboniferous and Triassic to Early Jurassic age generated considerable amounts of petroleum that may have contributed to the world-class petroleum resources of the North Slope. Deposits of Zn-Pb-Ag or barite as large as those in the Brooks Range are very rare on a global basis and, accordingly, multiple coincident favorable factors must be invoked to explain their origins. To improve our understanding of these factors and to contribute to more effective assessments of resources in sedimentary basins of northern Alaska and throughout the world, the Mineral Resources Program and the Energy Resources Program of the U.S. Geological Survey (USGS) initiated a project that was aimed at understanding the petroleum maturation and mineralization history of parts of the Brooks Range that were previously poorly characterized. The project, titled ?Regional Fluid Flow and Basin Modeling in Northern Alaska,? was undertaken in collaboration with industry, academia, and other government agencies. This Circular contains papers that describe the results of the recently completed project. The studies that are highlighted in these papers have led to a better understanding of the following: *The complex sedimentary facies relationships and depositional settings and the geochemistry of the sedimentary rocks that host the deposits (sections 2 and 3). *The factors responsible for formation of the barite and zinc deposits

  11. Tectonic evolution of Tethyan tectonic field, formation of Northern Margin basin and explorative perspective of natural gas in Tarim Basin

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Analyzing the characteristics of the Tethyan tectonic field, the authors think that the Tethyan tectonic field underwent three evolutional stages: closing of Paleo-Tethys and rifting of Neo-Tethys from early Permian to late Triassic, subduction of Neo-Tethys and collision between the Indian plate and the Eurasia plate from Jurassic to early of low Tertiary, and collision between the Arab plate and the Eurasia plate and the A-type subduction of Indian plate from late of low Tertiary to the present. Combining the evolution of the Tethyan orogenic belt with the characteristics of the Northern Margin basin, it is suggested that the sedimentary and tectonic characteristics and types of the Northern Mar-gin basin are controlled by the formation and evolution of the Tethyan orogenic belt and the ingression of Tethys. The evolution of Northern Margin basin can be divided into three development stages: back-arc foreland basin from late Permian to Triassic, the back-arc fault subsidence and depression from Jurassic to the early of low Tertiary, and the reactive foreland basin from the late of low Tertiary to the present. The Northern Margin basin in the Tethyan tectonic field is an important region for natural gas accumulation, and the Tarim Basin is a part of this region.

  12. Geochemical evolution of groundwater salinity at basin scale: a case study from Datong basin, Northern China.

    Science.gov (United States)

    Wu, Ya; Wang, Yanxin

    2014-05-01

    A hydrogeochemical investigation using integrated methods of stable isotopes ((18)O, (2)H), (87)Sr/(86)Sr ratios, Cl/Br ratios, chloride-mass balance, mass balance and hydrogeochemical modeling was conducted to interpret the geochemical evolution of groundwater salinity in Datong basin, northern China. The δ(2)H, δ(18)O ratios in precipitation exhibited a local meteoric water line of δ(2)H = 6.4 δ(18)O -5 (R(2) = 0.94), while those in groundwater suggested their meteoric origin in a historically colder climatic regime with a speculated recharge rate of less than 20.5 mm overall per year, in addition to recharge from a component of deep residual ancient lake water enriched with Br. According to the Sr isotope binary mixing model, the mixing of recharges from the Shentou karst springs (24%), the western margins (11%) and the eastern margins (65%) accounts for the groundwater from the deep aquifers of the down-gradient parts in the central basin is a possible mixing mechanism. In Datong, hydrolysis of silicate minerals is the most important hydrogeochemical process responsible for groundwater chemistry, in addition to dissolution of carbonate and evaporites. In the recharge areas, silicate chemical weathering is typically at the bisiallitization stage, while that in the central basin is mostly at the monosiallitization stage with limited evidence of being in equilibrium with gibbsite. Na exchange with bound Ca, Mg prevails at basin scale, and intensifies with groundwater salinity, while Ca, Mg exchange with bound Na locally occurs in the east pluvial and alluvial plains. Although groundwater salinity increases with the progress of water-rock/sediment interactions along the flow path, as a result of carbonate solubility control and continuous evapotranspiration, Na-HCO3 and Na-Cl-SO4 types of water are usually characterized respectively in the deep and the shallow aquifers of an inland basin with a silicate terrain in an arid climatic regime.

  13. Digital assessment of northern and central Appalachian basin coals

    Energy Technology Data Exchange (ETDEWEB)

    Ruppert, L.F.; Tewalt, S.J.; Braff, L.J.; Wallack, R.N. [US Geological Survey National Center, Reston, VA (US)

    1999-10-01

    The US Geological Survey (USGS) is currently conducting a coal resource assessment of the coalbeds and zones that are projected to provide the bulk of the nation's resources for the next few decades. The Pittsburgh and Upper Freeport coals are the first two beds in the northern and central Appalachian basin region to undergo fully digital coal assessments. The bed-specific assessments are being carried out in partnership with the state geologic surveys of West Virginia, Ohio, Pennsylvania and Maryland. Comprehensive stratigraphic and geochemical data-bases have been developed for both of the beds. The extent of the bed with mined areas, structure contour, isopach, and overburden thickness maps for the Pittsburgh coal bed have been realised as USGS open-file reports. The articles includes several detailed maps showing the export of the Pittsburgh coalbed, ash yield, sulphur contents and calorific value of the coal by county, structure contours, overburden thickness and isopac lines. 10 figs., 2 tabs.

  14. Review and analysis of existing Alberta data on drinking water quality and treatment facilities for the Northern River basins study. Northern River Basins Study project report No. 55

    Energy Technology Data Exchange (ETDEWEB)

    Prince, D.S.; Smith, D.W.; Stanley, S.J.

    1995-12-31

    This report summarizes the results of a project conducted to gather existing information about drinking water quality, drinking water facilities, and water treatment effectiveness in the area covered by the Northern River Basins Study (Peace, Slave, and Athabasca River basins in northern Alberta). The report includes a comparison of water treatment performance to the Canada Drinking Water Quality Guidelines. The appendices contain summaries of parameters in the treated water survey, of the comparisons between raw and treated water, and of samples not meeting the Guidelines, as well as an inventory of treatment facilities giving facility name and location, water source, community population, treatment method used, raw storage capacity, and treated volumes.

  15. Fluid flow in the northern Broad Fourteens Basin during Late Cretaceous inversion

    NARCIS (Netherlands)

    Oude Essink, Gualbert

    2003-01-01

    A basin-scale hydrogeological study of the inverted northern Broad Fourteens Basin, Netherlands offshore, has resulted in a reconstruction of geological evolution, an estimate of Late Cretaceous topography and model scenarios of syn-inversion meteoric water infiltration. This study was performed in

  16. Deep crustal structure of the Adare and Northern Basins, Ross Sea, Antarctica, from sonobuoy data

    Science.gov (United States)

    Selvans, M. M.; Stock, J. M.; Clayton, R. W.; Cande, S.; Granot, R.

    2014-11-01

    Extension associated with ultraslow seafloor spreading within the Adare Basin, in oceanic crust just north of the continental shelf in the Ross Sea, Antarctica, extended south into the Northern Basin. Magnetic and gravity anomaly data suggest continuity of crustal structure across the continental shelf break that separates the Adare and Northern Basins. We use sonobuoy refraction data and multi-channel seismic (MCS) reflection data collected during research cruise NBP0701, including 71 new sonobuoy records, to provide constraints on crustal structure in the Adare and Northern Basins. Adjacent 1D sonobuoy profiles along several MCS lines reveal deep crustal structure in the vicinity of the continental shelf break, and agree with additional sonobuoy data that document fast crustal velocities (6000-8000 m/s) at shallow depths (1-6 km below sea level) from the Adare Basin to the continental shelf, a structure consistent with that of other ultraslow-spread crust. Our determination of crustal structure in the Northern Basin only extends through sedimentary rock to the basement rock, and so cannot help to distinguish between different hypotheses for formation of the basin.

  17. Paleogene palaeogeography and basin evolution of the Western Carpathians, Northern Pannonian domain and adjoining areas

    Science.gov (United States)

    Kováč, Michal; Plašienka, Dušan; Soták, Ján; Vojtko, Rastislav; Oszczypko, Nestor; Less, György; Ćosović, Vlasta; Fügenschuh, Bernhard; Králiková, Silvia

    2016-05-01

    The data about the Paleogene basin evolution, palaeogeography, and geodynamics of the Western Carpathian and Northern Pannonian domains are summarized, re-evaluated, supplemented, and newly interpreted. The presented concept is illustrated by a series of palinspastic and palaeotopographic maps. The Paleogene development of external Carpathian zones reflects gradual subduction of several oceanic realms (Vahic, Iňačovce-Kričevo, Szolnok, Magura, and Silesian-Krosno) and growth of the orogenic accretionary wedge (Pieniny Klippen Belt, Iňačovce-Kričevo Unit, Szolnok Belt, and Outer Carpathian Flysch Belt). Evolution of the Central Western Carpathians is characterized by the Paleocene-Early Eocene opening of several wedge-top basins at the accretionary wedge tip, controlled by changing compressional, strike-slip, and extensional tectonic regimes. During the Lutetian, the diverging translations of the northward moving Eastern Alpine and north-east to eastward shifted Western Carpathian segment generated crustal stretching at the Alpine-Carpathian junction with foundation of relatively deep basins. These basins enabled a marine connection between the Magura oceanic realm and the Northern Pannonian domain, and later also with the Dinaridic foredeep. Afterwards, the Late Eocene compression brought about uplift and exhumation of the basement complexes at the Alpine-Carpathian junction. Simultaneously, the eastern margin of the stretched Central Western Carpathians underwent disintegration, followed by opening of a fore-arc basin - the Central Carpathian Paleogene Basin. In the Northern Hungarian Paleogene retro-arc basin, turbidites covered a carbonate platform in the same time. During the Early Oligocene, the rock uplift of the Alpine-Carpathian junction area continued and the Mesozoic sequences of the Danube Basin basement were removed, along with a large part of the Eocene Hungarian Paleogene Basin fill, while the retro-arc basin depocentres migrated toward the east

  18. Cenozoic evolution of the northwestern Salar de Atacama Basin, northern Chile

    Science.gov (United States)

    Pananont, P.; Mpodozis, C.; Blanco, N.; Jordan, T. E.; Brown, L. D.

    2004-12-01

    Since 90 Ma, the nonmarine Salar de Atacama Basin has been the largest, deepest, and most persistent sedimentary basin of northern Chile. Integration of 200 km of two-dimensional seismic reflection data with surface geological data clarifies Oligocene and Neogene evolution of the northern part of the basin. A normal fault with 6 ± 1 km of vertical separation controlled the western boundary of the basin during the accumulation of the Oligocene-lower Miocene Paciencia Group. The combination of this structure, a similar one in the Calama Basin, and regional structural data suggests that localized extension played an important role within a tectonic environment dominated by margin-perpendicular compression and margin-parallel strike-slip deformation. Seismic data substantiate the surface interpretation that much of the Cordillera de la Sal ridge resulted from diapiric flow of the Paciencia Group. Diapiric flow initiated during the late early Miocene or middle Miocene, associated with a deep reverse fault.

  19. Meso-Cenozoic basin evolution in northern Korean Peninsula

    Institute of Scientific and Technical Information of China (English)

    PAK Hyon Uk; LYANG To Jun; LIU Yongjiang; HYON Yun Su; KIM Gyong Chol

    2009-01-01

    In the Korean Peninsula the Meso-Cenozoic basins were mainly formed due to fault block and block movement. The Mesozoic fracture structures correspond basically to modern large rivers in direction. Such faults were usually developed to rift and formed lake-type tectonic basin, such as the Amrokgang-, Taedonggang-, Ryesonggang-, Hochongang-, Jangphari-, Susongchon-, Pujon-, and Nampho basins. The Mesozoic strata are considered to be divided into the Lower Jurassic Taedong System, Upper Jurassic Jasong System, Upper Jurassic- -early Lower Cretaceous Taebo System, and the Upper Cretaceous- -Paleocene (Chonjaebong, Hongwon, Jaedok Series). The Cenozoic block movement succeeded the Mesozoic fault block movement. The Kilju-Myongchon Graben and Tumangang Basin, etc, are the basins related to the fault zones developed from the Oligocene to Miocene. In addition, the Tertiary basins were formed in many areas in the Miocene (e.g. Sinhung, Oro, Hamhung, Yonghung, Anbyon, Cholwon, etc). The Cenozoic sedimentation occurred mainly from the late Oligocene to Miocene. The Kilju-Myongchon Graben was the fore deep connected to the sea and the basins inclined in the Chugaryong Fault Zone are intramountain basins. Therefore, coal-bearing beds and clastic rocks in the intramountain basins and rare marine strata and terrigenous clastic rocks are main sedimentary sequences in the Cenozoic.

  20. Multiple Refuge Bat Inventory: Great Basin & Great Northern LCC

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This was a cooperative project between the Upper Columbia Basin Network (UCBN) of the National Park Service I&M Program, USFWS Region 1 I&M Program (R1...

  1. Carbon cycling and budget in a forested basin of southwestern Hokkaido, northern Japan

    OpenAIRE

    Shibata, Hideaki; Hiura, Tsutom; Tanaka, Yumiko; Takagi, Kentaro; KOIKE, Takayoshi

    2005-01-01

    Quantification of annual carbon sequestration is very important in order to assess the function of forest ecosystems in combatting global climate change and the ecosystem responses to those changes. Annual cycling and budget of carbon in a forested basin was investigated to quantify the carbon sequestration of a cool-temperate deciduous forest ecosystem in the Horonai stream basin, Tomakomai Experimental Forest, northern Japan. Net ecosystem exchange, soil respiration, biomass increment, litt...

  2. Petroleum potential of the northern Sinu-San Jacinto Basin, Colombia: an integrated petroleum system and basin modeling approach

    Energy Technology Data Exchange (ETDEWEB)

    Nino, Christian H.; Goncalves, Felix T.T.; Bedregal, Ricardo P. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia (COPPE). Lab. de Modelagem de Bacias (LAB2M); Azevedo, Debora A. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Inst. de Quimica; Landau, Luis [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia (COPPE). Lab. de Metodos Computacionais em Engenharia (LAMCE)

    2004-07-01

    The northern Sinu-San Jacinto basin, located in the northwestern corner of South America (Colombia), belongs to the accretionary prism that resulted from the collision and subduction of the Caribbean plate under the South America plate. Despite all the previous exploratory efforts, solely a few small sub-commercial oil and gas accumulation have been found up to now. The geological and geochemical information acquired by different companies during the lasts decades was integrated with new geochemical analysis and basin modeling to characterize the petroleum systems, to reconstruct the hydrocarbon charge history in the study area and to better assess the exploratory risk. (author)

  3. Stratigraphic architecture of Devonian lacustrine basins of northern Scotland

    DEFF Research Database (Denmark)

    Kristiansen, Thorben; Moreau, Julien; Andrews, Steven D.;

    In Northeastern Scotland, the Orcadian Basin hosted large lacustrine systems which developed during Devonian times (c. 400 Ma). The pre-Devonian metamorphic basement unconformity is only exposed in a small number of places around the basin margin and therefore the characterization of the nature...... of this important surface has received relatively little attention. We have utilized vintage onshore seismic to gain a better understanding of the pre-Devonian basement physiography. Onshore exposures of the top Moine, base Devonian unconformity surface is exposed have been visited to ground truth our subsurface...... interpretations. The studied deposits have been deeply buried then exhumed so that they are exposed widely onshore. Post Caledonian tectonism has faulted and folded the Devonian succession making it challenging to reconstruct the stratigraphy and the basin architecture from geological data only. The Devonian...

  4. The U.S. Geological Survey`s National Coal Resource Assessment: The Northern and Central Appalachian Basin

    Energy Technology Data Exchange (ETDEWEB)

    Ruppert, L.; Bragg, L.; Tewalt, S. [Geological Survey, Reston, VA (United States)

    1996-09-01

    The US Geological Survey (USGS) Energy Resource Surveys Program is currently conducting a five-year National Coal Resource Assessment project. Primary focus is on the quality and quantity of top-producing coal beds and coal zones in five of the nine major coal producing regions in the US. These regions include the (1) Northern and Central Appalachian Basin, (2) Gulf Coastal Plain, (3) Illinois Basin, (4) Colorado Plateau, and (5) Powder River Basin and Northern Great Plains.

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

    OpenAIRE

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

    2016-01-01

    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...

  6. Tectonoestratigraphic and Thermal Models of the Tiburon and Wagner Basins, northern Gulf of California Rift System

    Science.gov (United States)

    Contreras, J.; Ramirez Zerpa, N. A.; Negrete-Aranda, R.

    2014-12-01

    The northern Gulf of California Rift System consist sofa series faults that accommodate both normal and strike-slip motion. The faults formed a series of half-greens filled with more than 7 km of siliciclastic suc­cessions. Here, we present tectonostratigraphic and heat flow models for the Tiburón basin, in the southern part of the system, and the Wag­ner basin in the north. The models are constrained by two-dimensional seis­mic lines and by two deep boreholes drilled by PEMEX­-PEP. Analysis of the seismic lines and models' results show that: (i) subsidence of the basins is controlled by high-angle normal faults and by flow of the lower crust, (ii) basins share a common history, and (iii) there are significant differences in the way brittle strain was partitioned in the basins, a feature frequently observed in rift basins. On one hand, the bounding faults of the Tiburón basin have a nested geometry and became active following a west-to-east sequence of activation. The Tiburon half-graben was formed by two pulses of fault activity. One took place during the protogulf extensional phase in the Miocene and the other during the opening of Gulf of California in the Pleistocene. On the other hand, the Wagner basin is the result of two fault generations. During the late-to middle Miocene, the west-dipping Cerro Prieto and San Felipe faults formed a domino array. Then, during the Pleistocene the Consag and Wagner faults dissected the hanging-wall of the Cerro Prieto fault forming the modern Wagner basin. Thermal modeling of the deep borehole temperatures suggests that the heat flow in these basins in the order of 110 mW/m2 which is in agreement with superficial heat flow measurements in the northern Gulf of California Rift System.

  7. Adaptation tot changing water resources in the Ganges basin, northern India

    NARCIS (Netherlands)

    Moors, E.J.; Groot, A.M.E.; Biemans, H.; Terwisscha van Scheltinga, C.T.H.M.; Siderius, C.; Stoffel, M.

    2011-01-01

    An ensemble of regional climate model (RCM) runs from the EU HighNoon project are used to project future air temperatures and precipitation on a 25 km grid for the Ganges basin in northern India, with a view to assessing impact of climate change on water resources and determining what multi-sector a

  8. Foraminiferal patterns in two trophically different regions: the northern Adriatic Sea and the southern Levantine Basin.

    NARCIS (Netherlands)

    Jannink, N.T.; Duijnstee, Ivo; van der Zwaan, Bert

    2001-01-01

    In spite of the fact that the northern Adriatic Sea and southern Levantine Basin are trophically quite different, the benthic foraminiferal standing stocks through the seasons were found to be in the same range. This suggests that the amount offood (organic matter) available at the sediment-water in

  9. Geothermal and Hydrocarbon Regimes, Northern Gulf of Mexico Basin

    Energy Technology Data Exchange (ETDEWEB)

    Jones, Paul H.

    1975-01-01

    Geothermal heat flow in the Gulf basin is primarily a function of its hydrology. Water expelled from sediments with deepening burial and increasing overburden load escapes upward and toward the basin margin. Where it moves freely in the hydropressure zone, the basin is relatively cool; but where rapid sedimentation and contemporaneous faulting have retarded water loss from compacting sediments, the interstitial fluid pressure reflects a part of the overburden load, and the formation waters are superheated and geopressured. The geopressured zone is common below depths of about 3 km (9,600 ft) in the basin, beneath an area of 375,000 km{sup 2} (150,000 mi{sup 2}), and extends downward perhaps 15 km (50,000 ft) to the base of Cenozoic deposits. The upper boundary of the geopressured zone is the most important physical interface in the basin. Across it the head of formation water increases downward from a few hundred to several thousand feet above sea level; the geothermal gradient increases downward from 20° to 40° C/km to 100°C/km or more; the salinity of formation water decreases downward, commonly by 50,000 mg/l or more; and the porosity of shale and sand increases downward by 10 to 25 percent. Petroleum matures in geopressured clay at 140° to 220°F. Montmorillonite is dehydrated at 180° to 250°F; fresh water released may equal half the volume of the mineral altered. Molecular solubility in fresh water of the hydrocarbons in Gulf basin crude, under geopressured zone conditions, could account for petroleum resources of the basin. Exsolution of petroleum hydrocarbons near the geopressured zone boundary could account for observed occurrences. This geopressured zone is a natural pressure vessel from which superheated water of moderate salinity could be produced through wells, each yielding millions of gallons a day at pressures of several thousand pounds per square inch, and temperatures above 300°F. with considerable amounts of methane gas in solution. (63

  10. Monthly Water Budget of Small Basin in Northern of Loess Plateau,China

    Institute of Scientific and Technical Information of China (English)

    HUANG Jinbai; HINOKIDANI Osamu; YASUDA Hiroshi; Kimura Reiji; ZHENG Jiyong

    2010-01-01

    The objective of this study was to analyze the water budget of a small basin in the northern of Loess Plateau. A small basin, Liudaogou in the northern Loess Plateau was chosen as the study area. The numerical calculation of surface runoff was applied to results of the field survey, and components of monthly water budget were estimated. The unit area of 1 km was selected as the index area for the estimation. A component of habitant water consumption was added to the water budget to consider the contribution of human activity. Results indicated that the water storage was negative in May, June and July while the annual amount was approximately 0.0. Evaportanspiration attained maximum in August and its annual total accounted for 74.2% of annual precipitation. Results of this study are significant for the sustainable water conservation and utilization in the northern of Loess Plateau where annual water resources are relatively deficient.

  11. Evidence for bloc rotation tectonics in the seismic Cheliff basin (northern Algeria) from paleomagnetic investigations

    Science.gov (United States)

    El-M. Derder, Mohamed; Henry, Bernard; Amenna, Mohamed; Bayou, Boualem; Maouche, Said; Besse, Jean; Ayache, Mohamed; Abtout, Abdeslam

    2010-05-01

    The seismic activity in the Western Mediterranean area is mainly concentrated in northern Africa, particularly in northern Algeria, as it was shown by the 21 May 2003 Boumerdes and the 10 October 1980 El Asnam earthquakes (of moment magnitudes Mw =6.9, and Ms= 7.3 respectively), which were among the strongest recent ones recorded in the western Mediterranean area. This seismicity is due to the convergence between Africa and Eurasia plates since at least the Oligocene. This convergence involves a transpression tectonic with N-S to NNW-SSE direction of shortening, which is expressed by active deformations along the boundary of these two plates. In Algeria, the seismicity is focused in a coastal zone (the Tell Atlas) in the northern part of the country. Active structures define there NE-SW trending folds and NE-SW sinistral transpressive faults, which affect the intermountain and coastal basins of Neogene to Quaternary age (e.g. " Cheliff "basin, " Mitidja "basin). These reverse faults are coupled with NW-SE to E-W trending strike-slip deep faults. The active deformation in northern Algeria could thus be explained by a kinematic model of bloc rotation: the transpression tectonics with NNW-SSE direction of convergence defines NE-SW oriented blocs, which have been possibly subjected to clockwise rotation. The aim of this study is to look for such blocks rotation in the "Cheliff" basin (northern Algeria), by using the paleomagnetic tool. A paleomagnetic study has been thus conducted on the midlle Miocene, Tortonian, Messinian and Pliocene sedimentary rocks cropping out on the eastern part of this basin. The study is still in progress, but despite the very weak intensity of the Natural Remanent Magnetization (NRM) measured on the samples, and the frequently observed magnetization instability during the thermal demagnetization, the preliminary results show that clockwise rotations have affected different sites of the studied area. The magnitude of these rotations varies

  12. Structure and seismic stratigraphy of deep Tertiary basins in the northern Aegean Sea

    Science.gov (United States)

    Beniest, Anouk; Brun, Jean-Pierre; Smit, Jeroen; Deschamps, Rémy; Hamon, Youri; Crombez, Vincent; Gorini, Christian

    2015-04-01

    Whereas active basin formation in the Aegean Sea is illustrated by seafloor bathymetry, the sedimentary and tectonic history of Tertiary basins is poorly known as existing offshore industrial seismic and well-log data are not easily accessible. We studied the evolution of the northern Aegean Sea with a focus on the North Aegean Trough and the Northern Skyros Basin, which are amongst the deepest basins of the northern Aegean domain. Structural and seismic stratigraphic interpretation of a 2D seismic dataset retrieved in the 1970's is combined with the well-investigated records of the onshore deep basins of northern Greece and Western Turkey. A general seismic signature chart was established using onshore basin stratigraphy and poorly-constrained well data. The studied domain shows two sharp unconformities that correspond to the Eocene-Oligocene transition and the Miocene-Pliocene shift, respectively. These transitions were then used as pillars for a more detailed structural and seismic stratigraphic interpretation. A NW-SE trending seismic line that cross-cuts the southern part of the NE-SW-trending North Aegean Through displays the main features that are observed in the area: 1) an overall basin geometry that is rather symmetrical; 2) pre-Pliocene units affected by steep normal faults; 3) a rather constant thickness of Oligocene sediments that define a depocenter with an apparent NW-SE orientation; 4) an ablation of Miocene sediments by erosion, likely related to the Messinian Salinity Crises (MSC); (5) thick deltaic/turbiditic deposits in the NE-SW oriented central through of Neogene age; 6) trans-tensional growth patterns in Pliocene and Quaternary sediments that combine NE-SW steeply dipping fault zones, more likely corresponding to strike-slip corridors, and E-W-trending normal faults. The evidence listed above suggest that, in the northern Aegean Sea, (1) extension started at the latest during the Late Eocene/Early Oligocene (data quality does not allow for a

  13. Crustal anisotropy from tectonic tremor in Guerrero, Mexico

    Science.gov (United States)

    Huesca-Pérez, Eduardo; Valenzuela, Raúl W.; Ortega, Roberto

    2016-06-01

    We present new shear wave anisotropy measurements in the continental crust in northern Guerrero obtained from tectonic tremor. Measurements of crustal anisotropy had not been performed in this area due to the lack of seismicity. However, tectonic tremor activity is abundant and offers an opportunity to determine anisotropy parameters. Polarization and splitting analyses were performed using broadband three-component seismograms. Results show that splitting times range between 0.07 and 0.36 s. These values are similar to the splitting magnitudes typically observed in the continental crust. The state of stress in the continental crust was investigated by inverting focal mechanisms determined in this study, and also from previous structural geology studies. Unfortunately, no stress measurements were possible in the area where tectonic tremor occurs. It was determined that, to the south of the study area, near the Pacific coast, and to the north, in the volcanic arc, the maximum compressive stress shows a general E-W trend. The fast polarization directions are oriented NE-SW and are oblique to the observed maximum compressive stress surrounding the study area. Thus, the relationship between the maximum compressive stress and the observed anisotropic pattern cannot be conclusively established. Several factors such as nonlinear strain in the continental crust as a result of Slow Slip Events, variations of pore fluid pressure, deep crustal mineralogy, and/or upper crust foliations and schistosity could be inducing the observed anisotropy pattern. In general, the fast axes tend to parallel the regional Laramide and Tertiary folds-and-thrusts which strike NNE-SSW. This system of folds-and-thrusts is highly foliated in low-grade schist and seems likely to control the anisotropic structure observed within the tectonic tremor region in Guerrero.

  14. Diversity of Bacteroidetes in high altitude saline evaporitic basins in northern Chile

    OpenAIRE

    Dorador, Cristina; Meneses, D.; Urtuvia, V.; Demergasso, C.; Vila, I; Witzel, K.-P.; Imhoff, Johannes F.

    2009-01-01

    The phylum Bacteroidetes represents one of the most abundant bacterial groups of marine and freshwater bacterioplankton. We investigated the diversity of Bacteroidetes in water and sediment samples from three evaporitic basins located in the highlands of northern Chile. We used both 16S rRNA gene clone libraries created with targeted Bacteroidetes-specific primers and separation of specifically amplified gene fragments by denaturing gradient gel electrophoresis (DGGE). DGGE analysis revealed ...

  15. Competition, Cooperation, and the Emergence of Regional Centers in the Northern Lake Titicaca Basin, Peru

    OpenAIRE

    Levine, Abigail Ruth

    2012-01-01

    Regional centers with dense populations developed in the Titicaca Basin during the late Middle (ca. 1300-500 BC) and early Upper Formative (ca. 500 BC- AD 400) Periods. These aggregated settlements have long been considered the hallmark of intermediate societies. This dissertation focuses on the transition from small village societies to ones with pronounced social, political, and economic hierarchies. In the northern Titicaca region, only two sites--Taraco and Pukara--became powerful cent...

  16. Analysis on structural control of coal distribution in the northern Qaidam Basin, NW China

    Energy Technology Data Exchange (ETDEWEB)

    Liu, T.J.; Wang, T.; Zhan, W.F. [Qinghai Bureau of Coal Geology, Xining (China)

    2008-06-15

    The distribution of the Jurassic coal measures in the northern Qaidam Basin is obviously controlled by the regional structures. Based on the existing data of coalfield exploration and combined with the analysis of coalfield basement structures, features of the main faults, and the distribution of coal measures, this paper brings forward a scheme of coalfield tectonic divisional units and the definition of the coal-controlling structural styles in the northern Qaidam Basin. The structure control of the distribution of coal measures is further discussed. Several stages of regional tectonic activities since the Indosinian has led to the distribution of coal measures into the characteristics of zonation from the north to south and block from east to west. The results indicate that the structural deformations are the most intense in the front of the three uplifted belts, which are characterized by the combination of thrusts. The coal measures are uplifted to the shallow formations, and are easy to be exploited, but the scale of mines is small because of serious damages by the coal distribution. On the contrary, the stress and strain are weak in the three depressions, with the coal-controlling structural styles being mainly the thrust-fold and thrust-monocline combinations. The distribution of coals in the depressions is relatively stable. The shallower part of the depression will become the key areas for exploration and development of coal resources in the northern Qaidam Basin.

  17. Analysis on Structural Control of Coal Distribution in the Northern Qaidam Basin, NW China

    Institute of Scientific and Technical Information of China (English)

    LIU Tianji; WANG Tong; ZHAN Wenfeng

    2008-01-01

    The distribution of the Jurassic coal measures in the northern Qaidam Basin is obviously controlled by the regional structures. Based on the existing data of coalfield exploration and combined with the analysis of coalfield basement structures, features of the main faults, and the distribution of coal measures, this paper brings forward a scheme of coalfield tectonic divisional units and the definition of the coal-controlling structural styles in the northern Qaidam Basin. The structure control of the distribution of coal measures is further discussed. Several stages of regional tectonic activities since the Indosinian has led to the distribution of coal measures into the characteristics of zonation from the north to south and block from east to west. The results indicate that the structural deformations are the most intense in the front of the three uplifted belts, which are characterized by the combination of thrusts. The coal measures are uplifted to the shallow formations, and are easy to be exploited, but the scale of mines is small because of serious damages by the coal distribution. On the contrary, the stress and strain are weak in the three depressions, with the coal-controlling structural styles being mainly the thrust-fold and thrust-monocline combinations. The distribution of coals in the depressions is relatively stable. The shallower part of the depression will become the key areas for exploration and development of coal resources in the northern Qaidam Basin.

  18. Tectonic control on the Late Quaternary hydrography of the Upper Tiber Basin (Northern Apennines, Italy)

    Science.gov (United States)

    Benvenuti, Marco; Bonini, Marco; Moroni, Adriana

    2016-09-01

    We examine the intramontane Upper Tiber Basin in the Northern Apennines (central Italy), where sub-orthogonal fault systems forced river deviation and the abandonment of alluvial fans since the late Middle Pleistocene. Archaeological material, spanning the Middle Palaeolithic-Iron Age, was collected mostly from the surface of the Late Quaternary alluvial landforms and related deposits (MUP and HOL units). This information contributed to the partial dating of seven major stages of drainage development. Normal faults parallel and transverse to the basin trend were active at different times and conditioned the valley pattern of the Middle (MUP1-2)-Late (MUP3) Pleistocene Tiber, Singerna, Sovara and Tignana rivers, which still flow today into the basin. The MUP1 and the MUP3 fans were beheaded by the displacement of their feeder valleys along the basin-transverse Carmine and Montedoglio faults. In some cases, the former feeder rivers underwent stream piracy but their courses mostly deviated in response of the topographic gradient created by faulting, as well as through the incision of new valleys that exploited the lithological contrast along the fault lines. The MUP3 Tignana fan was abandoned mostly due to the activity of the basin-parallel, dip-slip Sansepolcro fault. Subsidence driven by the basin-parallel Anghiari and Sansepolcro fault systems also provided the accommodation space for the MUP3 and HOl1-2 Afra fans between Late Pleistocene and early-mid Holocene. This study exemplifies the interplay between longitudinal and transverse fault systems, and the Late Quaternary hydrographic evolution of an extensional basin settled in the axial zone of an active fold-and-thrust belt. Although the faulting has interacted with the forcing exerted by the Late Quaternary climate fluctuations on the basin drainage systems, the tectonic rates are sufficiently high to represent the prime controller on base-level change and drainage routing patterns.

  19. Neotectonic of Dead Sea pull-apart basin. A new tectonic model for its northern closure

    Science.gov (United States)

    Al-Awabdeh, Mohammad; Pérez-Peña, J. Vicente; Azañón, J. Miguel; Booth-Rea, Guillermo

    2014-05-01

    The Dead Sea is a pull-apart basin formed by the relative motion of two active fault segments of the southern Dead Sea Transform Fault system (DSTF); the Wadi Araba Fault (WAF) and the Jordan Valley Fault (JVF) in northwest Jordan. Both of them are sinistral strike slip faults, however, the WAF has slightly faster slip-rate than the JVF. The northern termination of the Dead Sea basin is not well constrained, without clear transverse structures closing the basin. However, geophysical data suggest an abrupt thinning in this northern termination. Based on fieldwork and observations of recent tectonic structures, we suggest that the northern closure of this pull-apart basin corresponds to an active NW-SE normal fault system to the north of the Kafrain Dam (28 km southwest Amman; the capital of Jordan). These normal faults constitute a transtensional zone formed by the partial reactivation of two major structures; the Shueib and the Amman Hallabat structures (SHS and AHS). Normal faults dipping SW present low to moderate throws, lateral ramps coalescing in the SHS, and probably they merge into a low-dipping main plane. This fault system is also the responsible of the extension of the upper Cretaceous formations to the NE of Kafrain Dam and has associated colluvial wedges of Holocene sediments, indicating a seismic component with related small to medium earthquakes. This work reveals the Quaternary reactivation of tectonic structures that thought inactive in the Neogene and how they accommodate part of the stress in the region alongside with the DSFT.

  20. Status and understanding of groundwater quality in the Northern Coast Ranges study unit, 2009: California GAMA Priority Basin Project

    Science.gov (United States)

    Mathany, Timothy M.; Belitz, Kenneth

    2015-01-01

    Groundwater quality in the 633-square-mile (1,639-square-kilometer) Northern Coast Ranges (NOCO) study unit was investigated as part of the Priority Basin Project (PBP) of the Groundwater Ambient Monitoring and Assessment (GAMA) Program and the U.S. Geological Survey (USGS) National Water-Quality Assessment Program. The study unit is composed of two study areas (Interior Basins and Coastal Basins) and is located in northern California in Napa, Sonoma, Lake, Colusa, Mendocino, Glenn, Humboldt, and Del Norte Counties. The GAMA-PBP is being conducted by the California State Water Resources Control Board in collaboration with the USGS and the Lawrence Livermore National Laboratory.

  1. Tectonic Subsidence Analysis of the Pearl River Mouth Basin, Northern South China Sea

    Science.gov (United States)

    Tang, X.; Huang, S. S. X. E. C.; Zhuang, W.; LIU, Z.; Duan, W.; Hu, S.

    2015-12-01

    The Pearl River Mouth Basin (PRMB hereafter) in the northern margin of the South China Sea has attracted great attention not only because of its special tectonic location but also for its abundant hydrocarbon resources. Tectonic evolution controls the petroleum geological condition of hydrocarbon-bearing basins. Efforts have been made to understand the tectonic evolution of this basin. However, many issues about the tectonic features and the evolution process of this basin, such as the age of the breakup unconformities and the anomalously accelerated subsidence during the post-rifting stage, remain controversial. Here we employ tectonic subsidence analysis of sedimentary basins, a technique of removing isostatic loading and compaction effects by back-stripping, to investigate the tectonic controls on the basin formation of the PRMB. We performed the analysis on 4 drill wells and 43 synthetic wells constructed based on recently acquired seismic profiles. The result shows that tectonic subsidence in the eastern sags of the PRMB began to decrease at ~30Ma while in the western sags the onset was ~23.8Ma. This suggests that the break-up time i.e. the end of rifting in the PRMB is earlier in the eastern sags than in the western sags. Abnormally accelerated tectonic subsidence occurred between 17.5-16.4Ma during the post-rifting stage, at an average subsidence rate as high as 301.9m/Ma. This phenomenon discriminates the PRMB from the category of classical Atlantic passive continental marginal basins, of which the tectonic subsidence during the post-rifting stage decays exponentially. The main objective of this paper is to provide insights into the geological and geodynamic evolution of the PRMB. The result bears significance to hydrocarbon exploration in this region.

  2. Application of a technique for scenario prediction of climate change impact on the water balance components of northern river basins

    Directory of Open Access Journals (Sweden)

    Gusev Yeugeniy M.

    2014-09-01

    Full Text Available The scenario forecasting technique for assessing changes of water balance components of the northern river basins due to possible climate change was developed. Three IPCC global emission scenarios corresponding to different possible scenarios for economic, technological, political and demographic development of the human civilization in the 21st century were chosen for generating climate change projections by an ensemble of 16 General Circulation Models with a high spatial resolution. The projections representing increments of monthly values of meteorological characteristics were used for creating 3-hour meteorological time series up to 2063 for the Northern Dvina River basin, which belongs to the pan-Arctic basin and locates at the north of the European part of Russia. The obtained time series were applied as forcing data to drive the land surface model SWAP to simulate possible changes in the water balance components due to different scenarios of climate change for the Northern Dvina River basin

  3. Reassessing the 2006 Guerrero slow-slip event, Mexico: Implications for large earthquakes in the Guerrero Gap

    NARCIS (Netherlands)

    Bekaert, D.P.S.; Hooper, A.; Wright, T.J.

    2015-01-01

    In Guerrero, Mexico, slow-slip events have been observed in a seismic gap, where no earthquakes have occurred since 1911. A rupture of the entire gap today could result in a Mw 8.2–8.4 earthquake. However, it remains unclear how slow-slip events change the stress field in the Guerrero seismic region

  4. Hydrogeochemistry of high-fluoride groundwater at Yuncheng Basin, northern China

    International Nuclear Information System (INIS)

    Hydrogeochemical and environmental isotope methods were integrated to delineate the spatial distribution and enrichment of fluoride in groundwater at Yuncheng Basin in northern China. One hundred groundwater samples and 10 Quaternary sediment samples were collected from the Basin. Over 69% of the shallow groundwater (with a F− concentration of up to 14.1 mg/L), 44% of groundwater samples from the intermediate and 31% from the deep aquifers had F− concentrations above the WHO provisional drinking water guideline of 1.5 mg/L. Groundwater with high F− concentrations displayed a distinctive major ion chemistry: Na-rich and Ca-poor with a high pH value and high HCO3− content. Hydrochemical diagrams and profiles and hydrogen and oxygen isotope compositions indicate that variations in the major ion chemistry and pH are controlled by mineral dissolution, cation exchange and evaporation in the aquifer systems, which are important for F− mobilization as well. Leakage of shallow groundwater and/or evaporite (gypsum and mirabilite) dissolution may be the major sources for F− in groundwater of the intermediate and deep aquifers. - Highlights: • High-F− groundwater widely occurs in Yuncheng Basin of northern China. • High-F− groundwater is Na and HCO3-rich and Ca-poor, with high pH. • Major hydrogeochemical processes are mineral dissolution, ion exchange and evaporation. • Shallow groundwater leakage/evaporite dissolution may cause F enrichment in lower aquifers

  5. Characteristics and genesis of clay minerals in the northern margin of the Qaidam Basin

    Institute of Scientific and Technical Information of China (English)

    Wang Linlin; Jiang Bo; Peng Dehua; Yin Chengming; Zeng Chunlin

    2011-01-01

    In order to develop appropriate reservoir protection measures in the northern margin of the Qaidam Basin and improve its oil and gas recovery efficiency, characteristics of clay minerals from eleven clay rock samples from the northern margin of the Qaidam Basin were investigated using X-ray diffraction analysis, the Scanning Electron Microscope (SEM) and energy spectrum analysis. Clay mineral composition and distribution characteristics of the main hydrocarbon reservoirs, I.e., from the Jurassic and Paleogene-Neogene, were explored. We analyzed the main factors which affected these attributes. The results show that the major clay minerals in the northern margin are chlorite, kaolinite, illite, smectite and illite/smectite inter-stratified minerals, Illite is the most widely spread clay mineral in this area.Chlorite is mainly found in the entire Neogene and in shallow horizons of the Paleogene. Smectite is enriched in the shallow Paleogene-Neogene. There are large amounts of kaolinite and illite/smectite inter-stratified minerals in the Jurassic. The major factors affecting the different development of clay minerals in the region are properties of parent rocks, paleoclimate and paleowater media conditions,diagenesis transformation, tectonic and terrain conditions.

  6. Structural style and Basin Formation in Deep-water Area of Northern South China Sea

    Science.gov (United States)

    di, Z.; Zhen, S.; Xiong, P.; Min, C. C.

    2007-12-01

    In the deep-water area of northern South China Sea (SCS) developed a series of sedimentary basins. Active exploration for deep-water hydrocarbon has begun in these areas since this century. The well LW3-1-1 at water depth of 1480m in the BaiYun Sag (BYS) of the Pearl River Mouth Basin in 2006 discovered 56m layer of pure gas, demonstrated the good hydrocarbon potential of the area. Wide-angle seismic profiling has verified the transitional type of crust in the slope areas. The Moho surface shoals step-by-step from 30-29km under the shelf, ~15 km under the slope, and ~12km under the abyssal plain. Moho also rises beneath depocenters, mirroring the shape of sedimentary basement. The crustal thickness at the center of the BYS is Pacific Ocean towards the East Eurasian margin. The stress field in the East Eurasian margin changed abruptly in Late Cretaceous. Rifting started in the entire margin and eventually led to the opening of the SCS in late Early Oligocene. Large sedimentary basins developed in the margins of the SCS. Paleogene lacustrine sediments contain hydrocarbon sources, while traps are mostly found in Neogene marine strata. The structure of the northern SCS shows clear W-E variation, divided into NE-, NEE-, and NE-trending segments by two major NW-SE transfer faults. The Southern Depression of the Qiongdongnan Basin to the west is characterized by NE-trending half grabens. The BYS at the central segment is characterized by NEE-trending composite grabens and down warps with relatively small offset of boundary faults. To the east the Chaoshan Depression is composed of Mesozoic strata under very thin (deep-water basins is different from that of shallow-water basins. A study is ongoing to explore the basin formation mechanism, taking into account of the factors of abnormal lithosphere rheology, active mantle underplating and magmatic heating, lower crust flow, as well as the superposition of later extensional events. The study is supported by NSFC grants

  7. Federally owned coal and Federal lands in the northern and central Appalachian Basin coal regions

    Energy Technology Data Exchange (ETDEWEB)

    Susan J. Tewalt

    2002-02-01

    The US Geological Survey (USGS) assessed five coals beds or coal zones in the northern and central Appalachian Basin coal regions for the National Coal Resource Assessment: the Pittsburgh coal bed, the Upper Freeport coal bed, the Fire Clay coal zone, the Pond Creek coal zone, and the Pocahontas No. 3 coal bed. The assessment produced stratigraphic and geochemical databases and digital coal maps, or models, which characterized the coal beds and coal zones. Using the assessment models, the USGS estimated original and remaining (unmined) resources for these coal beds or zones. The Appalachian Basin assessment was conducted in collaboration with the State geological surveys of West Virginia, Pennsylvania, Ohio, Maryland, Kentucky, and Virginia. 3 refs., 7 figs.

  8. Coal resources of selected coal beds and zones in the northern and central Appalachian Basin

    Energy Technology Data Exchange (ETDEWEB)

    Leslie Ruppert; Susan Tewalt; Linda Bragg

    2002-02-01

    The U.S. Geological Survey (USGS) is completing a National Coal Resource Assessment of five coal-producing regions of the United States, including the Appalachian Basin. The USGS, in cooperation with the State geological surveys of Kentucky, Maryland, Ohio, Pennsylvania, Virginia, and West Virginia, has completed a digital coal resource assessment of five of the top-producing coal beds and coal zones in the northern and central Appalachian Basin coal regions -- the Pittsburgh coal bed, the Upper Freeport coal bed, the Fire Clay and Pond Creek coal zones, and the Pocahontas No. 3 coal bed. Of the 93 billion short tons of original coal in these units, about 66 billion short tons remain. 2 refs., 5 figs., 2 tabs.

  9. Triassic rift-related sedimentary basins in northern Chile (24° 29°S)

    Science.gov (United States)

    Suarez, M.; Bell, C. M.

    1992-10-01

    Triassic rocks in northern Chile (latitude 24°-29°S) include marine and continental rift-related sedimentary deposits, associated with basaltic, andesitic, and silicic volcanic rocks. Five main successions include the deposits of two marine basins (Profeta and San Félix) separated by three continental basins (Cifuncho, La Ternera, and La Coipa). The marine strata include turbidites and debris flow deposits interpreted as coarse-grained fan-delta sediments. The continental sediments include lacustrine fan delta, open lake, braided river, alluvial fan, and sabkha deposits. The widespread fan-delta systems (both marine and lacustrine), together with abrupt lateral and vertical facies discontinuities and large-scale depositional cycles, are indicative of rift-controlled sedimentation. The associated magmatic activity indicates that this rifting was the product of subduction-related extension or strike-slip movement on the active plate margin. Triassic rifting was followed in Late Triassic to Early Jurassic times by widespread thermotectonic subsidence.

  10. Late Cenozoic magnetic polarity stratigraphy in the Jiudong Basin, northern Qilian Mountain

    Institute of Scientific and Technical Information of China (English)

    赵志军; 方小敏; 李吉均

    2001-01-01

    Late Cenozoic sediments in the Hexi Corridor, foreland depression of the Qilian Mountain preserved reliable records on the evolution of the Northern Tibetan Plateau. Detailed magnetic polarity dating on a 1150 m section at Wenshushan anticline in the Jiudong Basin, west of Hexi Corridor finds that the ages of the Getanggou Formation, Niugetao Formation and Yumen Conglomerate are>11-8.6 Ma, 8.6-4.5 Ma and 4.5-0.9 Ma respectively. Accompanying sedimentary analysis on the same section suggests that the northern Tibetan Plateau might begin gradual uplift since 8.6-7.6 Ma, earlier than the northeastern Tibetan Plateau but does not suppose that the plateau has reached its maximum elevation at that time. The commencement of the Yumen Conglomerate indicates the intensive tectonic uplift since about 4.5 Ma.

  11. Latest Miocene to Quaternary deformation in the southern Chaiwopu Basin, northern Chinese Tian Shan foreland

    Science.gov (United States)

    Lu, Honghua; Wang, Zhen; Zhang, Tianqi; Zhao, Junxiang; Zheng, Xiangmin; Li, Youli

    2015-12-01

    Basinward propagation of fold and thrust belts is a crucial geological process accommodating Cenozoic crustal shortening within the India-Eurasia collision zone. Anticlinal growth strata in the southern Chaiwopu Basin (a piggyback basin) of the northern Chinese Tian Shan foreland record basinward encroachment of the Tian Shan along the Junggar Frontal Thrust Fault. A new magnetostratigraphic section constrains the onset of syntectonic growth strata at circa 6.4 Ma and suggests synchronous basinward thrusting and propagation of the Tian Shan. The intense alluviation in the southern Chaiwopu Basin ceased at circa 0.55 Ma due to significant anticlinal growth and its resultant river incision. More recent anticlinal growth and deformation during the late Quaternary are revealed by folded river terraces developing across the anticline. The terrace height profile indicates that terrace T1H has been vertically offset about 0.6 m by thrust faulting since its formation at about 7 Ka. The stratigraphic and geomorphic data presented in this work are helpful to understand the initiation of thrust-related folding, as well as aggradation and subsequent incision, in foreland basins of the Tian Shan in relation to the India-Asia collision.

  12. Geophysical observations on northern part of Georges Bank and adjacent basins of Gulf of Maine

    Science.gov (United States)

    Oldale, R.N.; Hathaway, J.C.; Dillon, William P.; Hendricks, J.D.; Robb, James M.

    1974-01-01

    Continuous-seismic-reflection and magnetic-intensity profiles provide data for inferences about the geology of the northern part of Georges Bank and the basins of the Gulf of Maine adjacent to the bank. Basement is inferred to be mostly sedimentary and volcanic rocks of Paleozoic age that were metamorphosed and intruded locally by felsic and mafic plutons near the end of the Paleozoic Era. During Late Triassic time, large fault basins formed within the Gulf of Maine and probably beneath Georges Bank. The fault basins and a possible major northeast-trending fault zone beneath the northern part of the bank probably formed as a result of the opening Atlantic during the Mesozoic. Nonmarine sediments, associated with mafic flows and intrusive rocks, were deposited in the fault basins as they formed. The upper surface of the Triassic and pre-Triassic rocks that comprise basement is an unconformity that makes up much of the bottom of the Gulf of Maine. Depth to the basement surface beneath the gulf differ greatly because of fluvial erosion in Tertiary time and glacial erosion in Pleistocene time. Beneath the northern part of Georges Bank the basement surface is smoother and slopes southward. Prominent valleys, cut before Late Cretaceous time, are present beneath this part of the bank. Cretaceous, Tertiary, and possibly Jurassic times were characterized by episodes of coastal-plain deposition and fluvial erosion. During this time a very thick wedge of sediment, mostly of Jurassic(?) and Cretaceous ages, was deposited on the shelf. Major periods of erosion took place at the close of the Cretaceous and during the Pliocene. Fluvial erosion during the Pliocene removed much of the coastal-plain sedimentary wedge and formed the Gulf of Maine. Pleistocene glaciers eroded all but a few remnants of the coastal-plain sediments within the gulf and deposited a thick section of drift against the north slope of Georges Bank and a thin veneer of outwash on the bank. Marine sediments were

  13. AN UPPER VISÉAN (ASBIAN-BRIGANTIAN AND SERPUKHOVIAN CORAL SUCCESSION AT DJEBEL OUARKZIZ (NORTHERN TINDOUF BASIN, SOUTHERN MOROCCO

    Directory of Open Access Journals (Sweden)

    SERGIO RODRÍGUEZ

    2013-03-01

    Full Text Available The Djebel Ouarkziz Formation, located in the northern part of the Tindouf Basin, in western Algeria and southern Morocco, is composed mainly of shales with interbedded limestones, dolostones and sandstones. The limestone beds are relatively thin, but are laterally persistent, and can be followed along strike for tens of kilometres. We have identified 19 limestone beds in three main sections; one logged along the road from Assa to Zag, a second in the Tinguiz-Remz Valley, 15 km to the east, and a third section 10 km west of the Assa-Zag road section. Rugose coral assemblages are recorded in most limestone beds, but the stratigraphically higher beds become more diverse However, many rugose genera and species are persistent throughout much of the succession. The oldest coral assemblages are Asbian in age and the youngest coral assemblages indicate a Serpukhovian age, as confirmed by foraminiferal biostratigraphy. The first appearance of rugose corals shows a different pattern than that in northern Moroccan basins; some common genera that first appear in the Asbian and lower Brigantian in northern Morocco and Europe, appear much later, in the upper Brigantian or Serpukhovian in the Djebel Ouarkziz. The genus Kizilia, which is rare in the Upper Viséan in northern Moroccan basins, is, however, abundant in the Tindouf Basin. Interestingly, the occurrence of the genus Lonsdaleia in the Serpukhovian from Djebel Ouarkziz poses a palaeogeographic problem because of its absence in northern Moroccan basins (except as transported elements in Serpukhovian conglomerates. Similarly, Actinocyathus in the Serpukhovian in the Tindouf Basin is not present north of the Anti-Atlas Mountains. A possible coral migration route to the Tindouf Basin may be from the northeast via the Béchar Basin in Algeria, similar to that already inferred for foraminifers and calcareous algae. 

  14. Recognition of relict Mesozoic Dongsha Basin in the northern margin, South China Sea and its implication

    Science.gov (United States)

    Yan, Pin; Wang, Yanlin

    2015-04-01

    The Pearl River Mouth Basin (PRMB) is dominated by NE-trending rift architecture produced mainly during Cenozoic Era. It comprises a series of grabens built up with thick Paleogene and thick Neogene sediments, up to 12000 m, and dividing basement highs composing Yanshanian granitic rocks. Though previously considered as one constituent part of PRMB in the southeast, Dongsha Basin displays major differences in sedimentary architecture and tectonic framework. Firstly, Dongsha Basin is characterized by a prominent angular unconformity, interpreted as a spectacular planation or rough erosion surface which separates the sediment column into two distinct parts. It is interpreted with accumulating seismic and drill data that the underlying strata comprise Early Cretaceous terrestrial, Jurassic marine and possibly Triassic sedimentary rocks totaling to 4~9 km thick, whereas the overlying strata are very thin (usually 0.5~1 km in whole) composing mainly Neogene sediments. The major sedimentary hiatus between them corresponds to the Late Cretaceous to mid-Miocene Epoch, well during the rifting to spreading process when the PRMB developed. Secondly, unlike the PRMB, the Dongsha Basin has suffered considerably less extension except its boundary areas, and actually remained as a relatively stable block though Cenozoic Era. Moreover, there are a few compressive open fold structures within the buried Mesozoic strata over the central Dongsha Basin. These folds trend in NNE and are characterized mostly by few minor growing upthrust faults with offsets in the order of few tens to hundreds meter. The upthrust faults dipped mostly southeastward against the northwestward subduction of paleo-Pacific plate as postulated in other previous study. The blind folds featured more like back-thrust growth tectonics, formed a broad NNE-SSW trending belt, obviously oblique to the trend of northern margin of the South China Sea and the PRMB as well. In a few recent models, the most prominent

  15. Extraordinarily thick-boned fish linked to the aridification of the Qaidam Basin (northern Tibetan Plateau).

    Science.gov (United States)

    Chang, Meemann; Wang, Xiaoming; Liu, Huanzhang; Miao, Desui; Zhao, Quanhong; Wu, Guoxuan; Liu, Juan; Li, Qiang; Sun, Zhencheng; Wang, Ning

    2008-09-01

    Scattered with numerous salt lakes and approximately 2,700-3,200 m above sea level, the giant Qaidam inland basin on the northern Tibetan Plateau has experienced continuing aridification since the beginning of the Late Cenozoic as a result of the India-Asia plate collision and associated uplift of the Tibetan Plateau. Previous evidence of aridification comes mainly from evaporite deposits and salinity-tolerant invertebrate fossils. Vertebrate fossils were rare until recent discoveries of abundant fish. Here, we report an unusual cyprinid fish, Hsianwenia wui, gen. et sp. nov., from Pliocene lake deposits of the Qaidam Basin, characterized by an extraordinarily thick skeleton that occupied almost the entire body. Such enormous skeletal thickening, apparently leaving little room for muscles, is unknown among extant fish. However, an almost identical condition occurs in the much smaller cyprinodontid Aphanius crassicaudus (Cyprinodonyiformes), collected from evaporites exposed along the northern margins of the Mediterranean Sea during the Messinian desiccation period. H. wui and A. crassicaudus both occur in similar deposits rich in carbonates (CaCO(3)) and sulfates (CaSO(4)), indicating that both were adapted to the extreme conditions resulting from the aridification in the two areas. The overall skeletal thickening was most likely formed through deposition of the oversaturated calcium and was apparently a normal feature of the biology and growth of these fish. PMID:18757732

  16. Diversity of Bacteroidetes in high-altitude saline evaporitic basins in northern Chile

    Science.gov (United States)

    Dorador, Cristina; Meneses, Daniela; Urtuvia, Viviana; Demergasso, Cecilia; Vila, Irma; Witzel, Karl-Paul; Imhoff, Johannes F.

    2009-06-01

    The phylum Bacteroidetes represents one of the most abundant bacterial groups of marine and freshwater bacterioplankton. We investigated the diversity of Bacteroidetes in water and sediment samples from three evaporitic basins located in the highlands of northern Chile. We used both 16S rRNA gene clone libraries created with targeted Bacteroidetes-specific primers and separation of specifically amplified gene fragments by denaturing gradient gel electrophoresis (DGGE). DGGE analysis revealed a reduced richness of these organisms in samples from Salar de Huasco (two to four DGGE bands) increasing in Salar de Ascotán (two to seven DGGE bands) and Laguna Tebenquiche at Salar de Atacama (four to eight DGGE bands). Cluster analysis (WPGMA) of DGGE bands showed that bands from Salar de Huasco and Salar de Ascotán grouped together and samples from Salar de Atacama formed separate clusters in water and sediment samples, reflecting different Bacteroidetes communities between sites. Most of the sequences analyzed belonged to the family Flavobacteriaceae and clustered with the genera Psychroflexus, Gillisia, Maribacter, Muricauda, Flavobacterium, and Salegentibacter. The most abundant phylotype was highly related to Psychroflexus spp. and was recovered from all three study sites. The similarity of the analyzed sequences with their closest relatives in GenBank was typically Culture efforts will be necessary to get a better description of the diversity of this group in saline evaporitic basins of northern Chile.

  17. Hydrogeochemistry of high-fluoride groundwater at Yuncheng Basin, northern China

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chengcheng [State Key Laboratory of Biogeology and Environmental Geology and School of Environmental Studies, China University of Geosciences, Wuhan 430074 (China); Gao, Xubo, E-mail: xubo.gao.cug@gmail.com [State Key Laboratory of Biogeology and Environmental Geology and School of Environmental Studies, China University of Geosciences, Wuhan 430074 (China); University of Texas at Austin, Austin, TX, 78705 (United States); Wang, Yanxin, E-mail: yx.wang@cug.edu.cn [State Key Laboratory of Biogeology and Environmental Geology and School of Environmental Studies, China University of Geosciences, Wuhan 430074 (China)

    2015-03-01

    Hydrogeochemical and environmental isotope methods were integrated to delineate the spatial distribution and enrichment of fluoride in groundwater at Yuncheng Basin in northern China. One hundred groundwater samples and 10 Quaternary sediment samples were collected from the Basin. Over 69% of the shallow groundwater (with a F{sup −} concentration of up to 14.1 mg/L), 44% of groundwater samples from the intermediate and 31% from the deep aquifers had F{sup −} concentrations above the WHO provisional drinking water guideline of 1.5 mg/L. Groundwater with high F{sup −} concentrations displayed a distinctive major ion chemistry: Na-rich and Ca-poor with a high pH value and high HCO{sub 3}{sup −} content. Hydrochemical diagrams and profiles and hydrogen and oxygen isotope compositions indicate that variations in the major ion chemistry and pH are controlled by mineral dissolution, cation exchange and evaporation in the aquifer systems, which are important for F{sup −} mobilization as well. Leakage of shallow groundwater and/or evaporite (gypsum and mirabilite) dissolution may be the major sources for F{sup −} in groundwater of the intermediate and deep aquifers. - Highlights: • High-F{sup −} groundwater widely occurs in Yuncheng Basin of northern China. • High-F{sup −} groundwater is Na and HCO{sub 3}-rich and Ca-poor, with high pH. • Major hydrogeochemical processes are mineral dissolution, ion exchange and evaporation. • Shallow groundwater leakage/evaporite dissolution may cause F enrichment in lower aquifers.

  18. Towards large scale modelling of wetland water dynamics in northern basins.

    Science.gov (United States)

    Pedinotti, V.; Sapriza, G.; Stone, L.; Davison, B.; Pietroniro, A.; Quinton, W. L.; Spence, C.; Wheater, H. S.

    2015-12-01

    Understanding the hydrological behaviour of low topography, wetland-dominated sub-arctic areas is one major issue needed for the improvement of large scale hydrological models. These wet organic soils cover a large extent of Northern America and have a considerable impact on the rainfall-runoff response of a catchment. Moreover their strong interactions with the lower atmosphere and the carbon cycle make of these areas a noteworthy component of the regional climate system. In the framework of the Changing Cold Regions Network (CCRN), this study aims at providing a model for wetland water dynamics that can be used for large scale applications in cold regions. The modelling system has two main components : a) the simulation of surface runoff using the Modélisation Environmentale Communautaire - Surface and Hydrology (MESH) land surface model driven with several gridded atmospheric datasets and b) the routing of surface runoff using the WATROUTE channel scheme. As a preliminary study, we focus on two small representative study basins in Northern Canada : Scotty Creek in the lower Liard River valley of the Northwest Territories and Baker Creek, located a few kilometers north of Yellowknife. Both areas present characteristic landscapes dominated by a series of peat plateaus, channel fens, small lakes and bogs. Moreover, they constitute important fieldwork sites with detailed data to support our modelling study. The challenge of our new wetland model is to represent the hydrological functioning of the various landscape units encountered in those watersheds and their interactions using simple numerical formulations that can be later extended to larger basins such as the Mackenzie river basin. Using observed datasets, the performance of the model to simulate the temporal evolution of hydrological variables such as the water table depth, frost table depth and discharge is assessed.

  19. Ellipticity of Rayleigh waves in basin and hard-rock sites in Northern Italy

    Science.gov (United States)

    Berbellini, Andrea; Morelli, Andrea; Ferreira, Ana M. G.

    2016-07-01

    We measure ellipticity of teleseismic Rayleigh waves at 95 seismic stations in Northern Italy, for wave period between 10 and 110 s, using an automatic technique and a large volume of high-quality seismic recordings from over 500 global earthquakes that occurred in 2008-2014. Northern Italy includes a wide range of crustal structures, from the wide and deep Po Plain sedimentary basin to outcropping sedimentary and crystalline rocks in the Northern Apennines and Alps. It thus provides an excellent case for studying the influence of shallow earth structure on polarization of surface waves. The ellipticity measurements show excellent spatial correlation with geological features in the region, such as high ellipticity associated with regions of low seismic velocity in the Po Plain and low ellipticity values in faster, hard rock regions in the Alps and Apennine mountains. Moreover, the observed ellipticity values also relate to the thickness of the basement, as highlighted by observed differences beneath the Alps and the Apennines. Comparison between observations and predicted ellipticity from a reference crustal model of the region show substantial fit, particularly for T ˜ 38 s data. Discrepancy for shorter wave period suggests that slight modifications of the model are needed, and that the ellipticity measurements could help to better constrain the shallow crustal structure of the region. Predictions for the Po Plain are larger than the observations by a factor of four or more and transition from retrograde to prograde Rayleigh wave motion at the surface for periods of T ˜ 10-13 s is predicted for seismic stations in the plain. Analysis of corresponding real data indicates a possible detection of teleseismic prograde particle motion, but the weak teleseismic earthquake signals are mixed with ambient noise signals at the predicted, short, transition periods. Detection of the period of polarity inversion from the joint analysis of earthquake and ambient noise

  20. The Millstone Grit Group (Pennsylvanian) of the Northumberland-Solway Basin and Alston Block of northern England

    OpenAIRE

    Waters, C.N; Millward, D.; C. W. Thomas

    2014-01-01

    In the Northumberland–Solway Basin and Alston Block of northern England, some aspects of the stratigraphical and sedimentological relationships between the Millstone Grit Group, the Stainmore Formation (Namurian part of the Yoredale Group) and the Westphalian Pennine Coal Measures Group are uncertain. Also, confusion has resulted from discontinuation of Millstone Grit as a formal lithostratigraphical term north of the Stainmore Basin. This paper presents the evidence for, and describes the na...

  1. Chemo- and biostratigraphy of the Late Jurassic from the Lower Saxony Basin, Northern Germany

    Science.gov (United States)

    Erbacher, Jochen; Luppold, Friedrich Wilhelm; Heunisch, Carmen; Heldt, Matthias; Caesar, Sebastian

    2013-04-01

    The upper Jurassic (Oxfordian to Tithonian) sediments of the Lower Saxony Basin (Northern Germany) comprises a succession of limestones, marlstones and claystones deposited in a shallow marine to lacustrine epicontinental basin situated between the Tethys and the Sub-Boreal seas. Both, the depositional environment and the palaeogeographically isolated position strongly compromise a chronostratigraphic dating of the regional lithostratigraphical and biostratigraphical units. In order to obtain a stratigraphic standard section for the Late Jurassic of the Lower Saxony Basin we drilled a 325 m long core (Core Eulenflucht 1) covering the lower part of the Berriasian (Wealden 2-3 of the Bückeburg Formation) to the lower Oxfordian (Heersum Formation). A compilation with a section outcropping in an active quarry 2 km north of the drill site resulted in a 340 m long section reaching down to the late Callovian (Ornatenton Formation) . Ammonites have only been described in the lowermost, Callovian part of the section. Investigations of benthic foraminifers, ostracods as well as palynology, however, allowed for a rather detailed biozonation of the core. These data indicate the stratigrapical completeness of the section when compared to the regional stratigraphic data of the Lower Saxony Basin. Due to the lack of ammonites in Late Jurassic part of the section, which would have allowed for a correlation with Tethyan successions, high resolution stable carbon isotope data have been produced from bulk rock carbonate. Even though most of the data derive from shallow marine, rather coarse grained carbonates, such as ooliths and floatstones the resulting carbon isotope curve is surprisingly clean with only little "noise" in the upper part (early Tithonian?) of the measured succession. The curve clearly shows some distinctive features reported from biostratigraphically well-dated carbon isotope records of the Northern Tethys (e.g. Bartolini et al., 2003, Padden et al., 2002, Rais et

  2. Formation Laws of Inorganic Gas Pools in the Northern Jiangsu Basin

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In the Northern Jiangsu basin there are high pure CO2 gas pools, low condensed oil-containing CO2 gas pools, high condensed oil-containing CO2 gas pools and He-containing natural gas pools, with the d 13Cco2 (PDB) values ranging from - 2.87to - 6.50 3He/4He 3.71×10- 6 to 6.42×10- 6, R/Ra 2.64 to 4.5, 40Ar/36Ar 705 to 734, belonging to typical mantle source inorganic gas pools which are related to young magmatic activity. The gas layers occur in two major reservoir-caprock systems, the terrestrial Meso-Cenozoic clastic rock system and the marine Meso-Palaeozoic carbonate rock-clastic rock system. Controlled by the difference in the scale of traps in the two reservoir-caprock systems, large and medium-scale inorganic gas pools are formed in the marine Meso-Palaeozoic Group and only small ones are formed in the terrestrial Meso-Cenozoic strata. Inorganic gas pools in this basin are distributed along the two deep lithospheric faults on the west and south boundaries of the basin. Gas pools are developed at the intersected part of the ENE-trending faults that control the half graben and the E-W tenso-shear faults, mainly distributed near the Es1, Ny1 and Ny2-Q basalt eruption centres.

  3. Water masses of the northern part of the Iceland Basin in the late Pleistocene

    Science.gov (United States)

    Lukashina, N. P.

    2013-02-01

    A core of bottom sediments AMK-4438 with a length of 320 cm was taken in the North-Eastern part of the Iceland Basin from the depth of 2240 m. The continuous sampling (every 2 cm) made it possible to study the core using the principle of high-resolving paleoceanology. For the stratigraphic partition of the core, we applied the paleotemperature analysis by planktonic foraminifera and carbonate analysis; the distribution of the iceberg rafted debris (IRD) was studied. As a result, nine isotopic stages were distinguished. The change in the complexes of benthic foraminifera indicates that the present-day deepwater circulation in the North-Eastern part of the Iceland Basin had no analogs in earlier glacial periods, including the MIS 5 age. During almost 300 ka, there were relatively warm, rich in nutrients, and poor in oxygen water masses. The formation of the modern Northern-Eastern deep water in the Iceland Basin began in the Bolling-Allerod 14 ka B.P.

  4. Alpine tectonics of granites in basement of Ysyk-Köl Basin, northern Tien Shan

    Science.gov (United States)

    Leonov, M. G.; Przhiyalgovsky, E. S.; Lavrushina, E. V.; Poleshchuk, A. V.; Rybin, A. K.

    2016-07-01

    The Ysyk-Köl Basin filled with Lower Jurassic-Quaternary sedimentary rocks is the largest intermontane negative structural unit of the northern Tien Shan. The basement of this basin is composed of Precambrian-Paleozoic rocks, largely of Ordovician and Silurian granitoids exposed in mountain ranges of the basin framework and as separate anticlinal domes situated in areas occupied by the Mesozoic-Cenozoic sedimentary cover. The postmagmatic tectonic internalstructure of the Chonkurchak (Chunkurchak), Kyzyl-Choku, Kyzyl-Bulak, and Prishib massifs emplaced in the basement, as well as their relationships to the sedimentary cover, are described in the paper. The study was carried out using the morphostructural method, detailed geological mapping, structural kinematic analysis, and petrographic examination of rocks. The internalstructure of Paleozoic granites in the basement and indications of their 3D tectonic flow are characterized. It is shown that granites underwent 3D deformation after their emplacement in the consolidated crust, and this process had a substantial influence on tectonic processes at the plate and orogenic stages of regional evolution.

  5. [Historical exploration of Acapulco hospitals, Guerrero, Mexico].

    Science.gov (United States)

    Fajardo-Ortiz, Guillermo; Salcedo-Alvarez, Rey Arturo

    2006-01-01

    This study attempts to recount the history of the main hospitals of the port of Acapulco from colonial times until the end of the 20th century. The Augustine friars began hospital care at the end of the first part of the 16th century. Later, Bernardino Alvarez (1514?-1584), with the support of the Spanish crown, founded the first formal hospital in Acapulco called Hospital de Nuestra Señora de la Consolación (Our Lady of Consolation Hospital). During the 16th and 17th centuries, the sick were attended by friars, and by the end of the 19th century there were physicians and surgeons. From the end of the Independence War until the end of the 19th century, the port did not have any true hospital. The first degreed physicians and surgeons arrived and resided in Acapulco in 1920. In 1938, the Hospital Civil Morelos (Morelos Civil Hospital) began providing services. It was replaced by the Hospital General de Acapulco (General Hospital of Acapulco). At the fourth decade of the past century the Cruz Roja (Red Cross) was created. In 1957 the hospital services of the Instituto Mexicano del Seguro Social (IMSS, Mexican Institute of Social Security), which was founded in 1963, was inaugurated with the Unidad Medico/Social (Medical and Social Unit) of the IMSS in Acapulco. This began the journey of modernity in Acapulco. In 1992, Hospital Regional Vicente Guerrero (Regional Hospital Vicente Guerrero) of the IMSS, initiated its services. In 1960, medical services for civil workers and their families were housed in the Hospital Civil Morelos (Morelos Civil Hospital). Shortly afterwards, the Instituto de Seguridad y Servicios Sociales para los Trabajadores del Estado (ISSSTE, Security and Social Services Institute for State Employees) had their own hospital. During the 20th century, Acapulco has added other hospital services to care for members of the navy and armed forces, as well as for those persons with financial resources for private care.

  6. Polyphase tectonic subsidence evolution of the Vienna Basin inferred from quantitative subsidence analysis of the northern and central parts

    Science.gov (United States)

    Lee, Eun Young; Wagreich, Michael

    2016-04-01

    The Vienna Basin is a tectonically complex Neogene basin situated at the Alpine-Carpathian transition. This study analyzes a detailed quantification of subsidence in the northern and central parts of the Vienna Basin to understand its tectonic subsidence evolution. About 200 wells were used to arrange stratigraphic setting, and wells reaching the pre-Neogene basement were analyzed for subsidence. To enhance the understanding of the regional subsidences, the wells were sorted into ten groups based on their position on major fault blocks. In the Early Miocene, subsidence was slow and along E-W to NE-SW trending axis, indicating the development of thrust-controlled piggyback basins. During the late Early Miocene data show abruptly increasing subsidence, making the initiation of the Vienna pull-apart basin system. From the Middle Miocene, the tectonic subsidence curves show regionally different patterns. The tectonic subsidence during the Middle Miocene varies laterally across the Vienna Basin, and the differential subsidence can be related to the changing tensional regime of weakening transtension and strengthening extension toward the late Middle Miocene. From the late Middle Miocene to the Late Miocene, the tectonic subsidence occurred dominantly along the regional active faults, and corresponds to the axis of E-W trending extension of the western parts of the Pannonian Basin system. In the Quaternary the Vienna Basin has been reactivated, and resulted in subsidence along the NE-SW trending Vienna Basin transfer fault system.

  7. Formation of hydrothermal deposits at Kings Triple Junction, northern Lau back-arc basin, SW Pacific: The geochemical perspectives

    Digital Repository Service at National Institute of Oceanography (India)

    Paropkari, A.L.; Ray, D.; Balaram, V.; Prakash, L.S.; Mirza, I.H.; Satyanarayana, M.; Rao, T.G.; Kaisary, S.

    An inactive hydrothermal field was discovered near Kings Triple Junction (KTJ) in northern Lau back-arc basin during 19th cruise of R/V Akademik Mstislav Keldysh in 1990. The field consisted of a large elongated basal platform ‘the pedestal...

  8. A Very Large Population of Likely Buried Impact Basins in the Northern Lowlands of Mars Revealed by MOLA Data

    Science.gov (United States)

    Frey, H. V.; Shockey, K. M.; Frey, E. L.; Roark, J. H.; Sakimoto, S. E. H.

    2001-01-01

    High resolution Mars Orbiter Laser Altimeter (MOLA) data have revealed a large number of subdued quasi-circular depressions (QCDs) >50 km diameter in the northern lowlands of Mars which are generally not visible in Viking imagery and which may be buried ancient impact basins. Additional information is contained in the original extended abstract.

  9. Geodynamic evolution and sedimentary infill of the northern Levant Basin: A source to sink-perspective

    Science.gov (United States)

    Hawie, N.

    2013-12-01

    Nicolas Hawie a,b,c (nicolas.hawie@upmc.fr) Didier Granjeon c (didier.granjeon@ifpen.fr) Christian Gorini a,b (christian.gorini@upmc.fr) Remy Deschamps c (remy.deschamps@ifpen.fr) Fadi H. Nader c (fadi-henri.nader@ifpen.fr) Carla Müller Delphine Desmares f (delphine.desmares@upmc.fr) Lucien Montadert e (lucien.montadert@beicip.com) François Baudin a (francois.baudin@upmc.fr) a UMR 7193 Institut des Sciences de la Terre de Paris, Université Pierre et Marie Curie/ Univ. Paris 06, case 117. 4, place Jussieu 75252 Paris Cedex 05, France b iSTEP, UMR 7193, CNRS, F-75005, Paris, France c IFP Energies nouvelles, 1-4 avenue du Bois Préau 92852 Rueil Malmaison Cedex, France d UMR 7207, Centre de Recherche sur la Paleobiodiversité et les Paleoenvironnements. Université Pierre et Marie Curie, Tour 46-56 5ème. 4, place Jussieu 75252 Paris Cedex 05, France e Beicip Franlab, 232 Av. Napoléon Bonaparte, 95502 Rueil-Malmaison, France Sedimentological and biostratigraphic investigations onshore Lebanon coupled with 2D offshore reflection seismic data allowed proposing a new Mesozoic-Present tectono-stratigraphic framework for the northern Levant Margin and Basin. The seismic interpretation supported by in-depth facies analysis permitted to depict the potential depositional environments offshore Lebanon as no well has yet been drilled. The Levant region has been affected by successive geodynamic events that modified the architecture of its margin and basin from a Late Triassic to Middle Jurassic rift into a Late Cretaceous subduction followed by collision and Miocene-Present strike slip motion. The interplay between major geodynamic events as well as sea level fluctuations impacted on the sedimentary infill of the basin. During Jurassic and Cretaceous, the Levant Margin is dominated by the aggradation of a carbonate platform while deepwater mixed-systems prevailed in the basin. During the Oligo-Miocene, three major sedimentary pathways are expected to drive important

  10. Facies-controlled volcanic reservoirs of northern Songliao Basin, NE China

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Volcanic rocks of the late Mesozoic are very important reservoirs for the commercial natural gases including hydrocarbon, carbon dioxide and rare gases in the northern Songliao Basin. The reservoir volcanic rocks include rhyolite,andesite, trachyte, basalt and tuff. Facies of the volcanic rocks can be classified into 5 categories and 15 special types.Porosity and permeability of the volcanic reservoirs are facies-controlled. Commercial reservoirs were commonly found among the following volcanic subfacies: volcanic neck (Ⅰ1), underground-explosive breccia (Ⅰ3), pyroclastic-bearing lava flow (Ⅱ3), upper effusive (Ⅲ3) and inner extrusive ones (Ⅳ1). The best volcanic reservoirs are generally evolved in the interbedded explosive and effusive volcanics. Rhyolites show in general better reservoir features than other types of rocks do.

  11. Radon measurements along active faults in the Langadas Basin, northern Greece

    Directory of Open Access Journals (Sweden)

    C. Papastefanou

    2001-01-01

    Full Text Available A network of three radon stations has been established in the Langadas Basin, northern Greece for radon monitoring by various techniques in earthquake prediction studies. Specially made devices with plastic tubes including Alpha Tracketch Detectors (ATD were installed for registering alpha particles from radon and radon decay products exhaled from the ground, every 2 weeks, by using LR-115, type II, non-strippable Kodak films, starting from December 1996. Simultaneous measurements started using Lucas cells alpha spectrometer for instantaneous radon measurements in soil gas, before and after setting ATDs at the radon stations. Continuous monitoring of radon gas exhaling from the ground started from the middle of August 1999 by using silicon diode detectors, which simultaneously register meteorological parameters, such as rainfall, temperature and barometric pressure. The obtained data were studied together with the data of seismic events, such as the magnitude, ML, of earthquakes that occurred at the Langadas Basin during the period of measurements, as registered by the Laboratory of Geophysics, Aristotle University of Thessaloniki, in order to find out any association between them.

  12. Hydrogeochemistry of high-fluoride groundwater at Yuncheng Basin, northern China.

    Science.gov (United States)

    Li, Chengcheng; Gao, Xubo; Wang, Yanxin

    2015-03-01

    Hydrogeochemical and environmental isotope methods were integrated to delineate the spatial distribution and enrichment of fluoride in groundwater at Yuncheng Basin in northern China. One hundred groundwater samples and 10 Quaternary sediment samples were collected from the Basin. Over 69% of the shallow groundwater (with a F(-) concentration of up to 14.1mg/L), 44% of groundwater samples from the intermediate and 31% from the deep aquifers had F(-) concentrations above the WHO provisional drinking water guideline of 1.5mg/L. Groundwater with high F(-) concentrations displayed a distinctive major ion chemistry: Na-rich and Ca-poor with a high pH value and high HCO3(-) content. Hydrochemical diagrams and profiles and hydrogen and oxygen isotope compositions indicate that variations in the major ion chemistry and pH are controlled by mineral dissolution, cation exchange and evaporation in the aquifer systems, which are important for F(-) mobilization as well. Leakage of shallow groundwater and/or evaporite (gypsum and mirabilite) dissolution may be the major sources for F(-) in groundwater of the intermediate and deep aquifers. PMID:25478652

  13. Arsenic release by indigenous bacteria Bacillus cereus from aquifer sediments at Datong Basin, northern China

    Science.gov (United States)

    Xie, Zuoming; Wang, Yanxin; Duan, Mengyu; Xie, Xianjun; Su, Chunli

    2011-03-01

    Endemic arsenic poisoning due to long-term drinking of high arsenic groundwater has been reported in Datong Basin, northern China. To investigate the effects of microbial activities on arsenic mobilization in contaminated aquifers, Bacillus cereus ( B. cereus) isolated from high arsenic aquifer sediments of the basin was used in our microcosm experiments. The arsenic concentration in the treatment with both bacteria and sodium citrate or glucose had a rapid increase in the first 18 d, and then, it declined. Supplemented with bacteria only, the concentration could increase on the second day. By contrast, the arsenic concentration in the treatment supplemented with sodium citrate or glucose was kept very low. These results indicate that bacterial activities promoted the release of arsenic in the sediments. Bacterial activities also influenced other geochemical parameters of the aqueous phase, such as pH, Eh, and the concentrations of dissolved Fe, Mn, and Al that are important controls on arsenic release. The removal of Fe, Mn, and Al from sediment samples was observed with the presence of B. cereus. The effects of microbial activities on Fe, Mn, and Al release were nearly the same as those on As mobilization. The pH values of the treatments inoculated with bacteria were lower than those without bacteria, still at alkaline levels. With the decrease of Eh values in treatments inoculated with bacteria, the microcosms became more reducing and are thus favorable for arsenic release.

  14. Arsenic release by indigenous bacteria Bacillus cereus from aquifer sediments at Datong Basin, northern China

    Institute of Scientific and Technical Information of China (English)

    Zuoming XIE; Yanxin WANG; Mengyu DUAN; Xianjun XIE; Chunli SU

    2011-01-01

    Endemic arsenic poisoning due to long-term drinking of high arsenic groundwater has been reported in Datong Basin, northern China. To investigate the effects of microbial activities on arsenic mobilization in contaminated aquifers, Bacillus cereus (B. cereus) isolated from high arsenic aquifer sediments of the basin was used in our microcosm experiments. The arsenic concentration in the treatment with both bacteria and sodium citrate or glucose had a rapid increase in the first 18 d, and then, it declined.Supplemented with bacteria only, the concentration could increase on the second day. By contrast, the arsenic concentration in the treatment supplemented with sodium citrate or glucose was kept very low. These results indicate that bacterial activities promoted the release of arsenic in the sediments. Bacterial activities also influenced other geochemical parameters of the aqueous phase, such as pH,Eh, and the concentrations of dissolved Fe, Mn, and Al that are important controls on arsenic release. The removal of Fe, Mn, and Al from sediment samples was observed with the presence of B. cereus. The effects of microbial activities on Fe, Mn, and Al release were nearly the same as those on As mobilization. The pH values of the treatments inoculated with bacteria were lower than those without bacteria, still at alkaline levels. With the decrease of Eh values in treatments inoculated with bacteria, the microcosms became more reducing and are thus favorable for arsenic release.

  15. Gravity analysis of the Precambrian basement topography associated with the northern boundary of Ghadames Basin (southern Tunisia)

    Science.gov (United States)

    Dhaoui, Mohamed; Gabtni, Hakim; Jallouli, Chokri; Jleilia, Ali; Mickus, Kevin Lee; Turki, Mohamed Moncef

    2014-12-01

    Gravity data were analyzed to determine the structural development of the northern boundary of the Ghadames Basin in southern Tunisia. The Ghadames Basin which also occurs in eastern Algeria and northwestern Libya is one of the most prolific hydrocarbon producers in North Africa with several of the largest oil fields occurring along its northern boundary. The Ghadames Basin was formed during a series of tectonic events ranging from the Early Paleozoic to the Early Cenozoic. These tectonic events produced a basin in southern Tunisia that has a complex basement configuration which is not completely known. A residual gravity anomaly map constructed using polynomial trend surfaces, and vertical and horizontal gravity derivative maps indicate that the northern boundary contains a series of maxima and minima anomalies that trend in two prominent directions: northeast-southwest and east-west. The horizontal and vertical derivative gravity anomaly maps indicate that the width of the basement structures range between 10 and 20 km in width. Three-dimensional (3D) Euler deconvolution and 3D forward modeling constrained by well data, one seismic reflection profile and remote sensing data confirm the width of the basement structures and indicates that the depth of basin varies between 1.5 and 5 km, with deeper sections in general more numerous in the southern sections of the boundary. The gravity analysis constrained by the seismic reflection profile and well data implies that the basement topography may have been formed during the Pan African and/or late Mesozoic rifting. However, additional seismic reflection and well data are needed to confirm this conclusion. The discovery of the numerous basement structures suggests that there may exist additional hydrocarbon traps within the northern boundary of the Ghadames Basin.

  16. Land cover changes associated with recent energy development in the Williston Basin; Northern Great Plains, USA.

    Science.gov (United States)

    Preston, Todd M; Kim, Kevin

    2016-10-01

    The Williston Basin in the Northern Great Plains has experienced rapid energy development since 2000. To evaluate the land cover changes resulting from recent (2000-2015) development, the area and previous land cover of all well pads (pads) constructed during this time were determined, the amount of disturbed and reclaimed land adjacent to pads was estimated, land cover changes were analyzed over time for three different well types, and the effects from future development were predicted. The previous land cover of the 12,990ha converted to pads was predominately agricultural (49.5%) or prairie (47.4%) with lesser amounts of developed (2.3%), aquatic (0.5%), and forest (0.4%). Additionally, 12,121ha has likely been disturbed and reclaimed. The area required per gas well remained constant through time while the land required per oil well increased initially and then decreased as development first shifted from conventional to unconventional drilling and then to multi-bore pads. For non-oil-and-gas wells (i.e. stratigraphic test wells, water wells, and injection wells), the area per well increased through time likely due to increased produced water disposal requirements. Future land cover change is expected to be 2.7 times greater than recent development with much of the development occurring in five counties in the core Bakken development area. Direct land cover change and disturbance from recent and expected development are predicted to affect 0.4% of the landscape across the basin; however, in the core Bakken development area, 2.3% of the landscape will be affected including 2.1% of the remaining grassland. Although future development will result in significant land cover change, evolving industry practices and proactive siting decisions, such as development along energy corridors and placing pads in areas previously altered by human activity, have the potential to reduce the ecological effects of future energy development in the Williston Basin.

  17. Source identification of fine-grained suspended sediment in the Kharaa River basin, northern Mongolia

    International Nuclear Information System (INIS)

    Fine sediment inputs into river systems can be a major source of nutrients and heavy metals and have a strong impact on water quality and ecosystem functions of rivers and lakes, including those in semiarid regions. However, little is known to date about the spatial distribution of sediment sources in most large scale river basins in Central Asia. Accordingly, a sediment source fingerprinting technique was used to assess the spatial sources of fine-grained (< 10 μm) sediment in the 15 000 km2 Kharaa River basin in northern Mongolia. Variation in geochemical composition (e.g. in Ti, Sn, Mo, Mn, As, Sr, B, U, Ca and Sb) was used for sediment source discrimination with geochemical composite fingerprints based on Genetic Algorithm (GA)-driven Discriminant Function Analysis, the Kruskal–Wallis H-test and Principal Component Analysis. All composite fingerprints yielded a satisfactory GOF (> 0.97) and were subsequently used for numerical mass balance modelling with uncertainty analysis. The contributions of the individual sub-catchment spatial sediment sources varied from 6.4% (the headwater sub-catchment of Sugnugur Gol) to 36.2% (the Kharaa II sub-catchment in the middle reaches of the study basin), generally showing higher contributions from the sub-catchments in the middle, rather than the upstream, portions of the study area. The importance of river bank erosion is shown to increase from upstream to midstream tributaries. The source tracing procedure provides results in reasonable accordance with previous findings in the study region and demonstrates the applicability and associated uncertainties of the approach for fine-grained sediment source investigation in large scale semi-arid catchments. - Highlights: • Applied statistical approach for selecting composite fingerprints in Mongolia. • Geochemical fingerprinting for the definition of source areas in semiarid catchment. • Test of applicability of sediment sourcing in large scale semi-arid catchments.

  18. Source identification of fine-grained suspended sediment in the Kharaa River basin, northern Mongolia

    Energy Technology Data Exchange (ETDEWEB)

    Theuring, Philipp [Department of Aquatic Ecosystem Analysis and Management — ASAM, Helmholtz Centre for Environmental Research — UFZ, Brückstrasse 3a, D-39114 Magdeburg (Germany); Collins, Adrian L. [Sustainable Soils and Grassland Systems Department, Rothamsted Research, North Wyke, Okehampton, Devon EX20 2SB (United Kingdom); Rode, Michael [Department of Aquatic Ecosystem Analysis and Management — ASAM, Helmholtz Centre for Environmental Research — UFZ, Brückstrasse 3a, D-39114 Magdeburg (Germany)

    2015-09-01

    Fine sediment inputs into river systems can be a major source of nutrients and heavy metals and have a strong impact on water quality and ecosystem functions of rivers and lakes, including those in semiarid regions. However, little is known to date about the spatial distribution of sediment sources in most large scale river basins in Central Asia. Accordingly, a sediment source fingerprinting technique was used to assess the spatial sources of fine-grained (< 10 μm) sediment in the 15 000 km{sup 2} Kharaa River basin in northern Mongolia. Variation in geochemical composition (e.g. in Ti, Sn, Mo, Mn, As, Sr, B, U, Ca and Sb) was used for sediment source discrimination with geochemical composite fingerprints based on Genetic Algorithm (GA)-driven Discriminant Function Analysis, the Kruskal–Wallis H-test and Principal Component Analysis. All composite fingerprints yielded a satisfactory GOF (> 0.97) and were subsequently used for numerical mass balance modelling with uncertainty analysis. The contributions of the individual sub-catchment spatial sediment sources varied from 6.4% (the headwater sub-catchment of Sugnugur Gol) to 36.2% (the Kharaa II sub-catchment in the middle reaches of the study basin), generally showing higher contributions from the sub-catchments in the middle, rather than the upstream, portions of the study area. The importance of river bank erosion is shown to increase from upstream to midstream tributaries. The source tracing procedure provides results in reasonable accordance with previous findings in the study region and demonstrates the applicability and associated uncertainties of the approach for fine-grained sediment source investigation in large scale semi-arid catchments. - Highlights: • Applied statistical approach for selecting composite fingerprints in Mongolia. • Geochemical fingerprinting for the definition of source areas in semiarid catchment. • Test of applicability of sediment sourcing in large scale semi-arid catchments

  19. Land cover changes associated with recent energy development in the Williston Basin; Northern Great Plains, USA

    Science.gov (United States)

    Preston, Todd M.; Kim, Kevin

    2016-01-01

    The Williston Basin in the Northern Great Plains has experienced rapid energy development since 2000. To evaluate the land cover changes resulting from recent (2000 – 2015) development, the area and previous land cover of all well pads (pads) constructed during this time was determined, the amount of disturbed and reclaimed land adjacent to pads was estimated, land cover changes were analyzed over time for three different well types, and the effects from future development were predicted. The previous land cover of the 12,990 ha converted to pads was predominately agricultural (49.5%) or prairie (47.4%) with lesser amounts of developed (2.3%), aquatic (0.5%), and forest (0.4%). Additionally, 12,121 ha have likely been disturbed and reclaimed. The area required per gas well remained constant through time while the land required per oil well increased initially and then decreased as development first shifted from conventional to unconventional drilling and then to multi-bore pads. For non-oil-and- gas wells (i.e. stratigraphic test wells, water wells, injection wells, etc.), the area per well increased through time likely due to increased produced water disposal requirements. Future land cover change is expected to be 2.7 times greater than recent development with much of the development occurring in five counties in the core Bakken development area. Direct land cover change and disturbance from recent and expected development are predicted to affect 0.4% of the landscape across the basin; however, in the core Bakken development area, 2.3% of the landscape will be affected including 2.1% of the remaining grassland. Although future development will result in significant land cover change, evolving industry practices and proactive siting decisions, such as development along energy corridors and placing pads in areas previously altered by human activity, have the potential to reduce the ecological effects of future energy development in the Williston Basin.

  20. Land cover changes associated with recent energy development in the Williston Basin; Northern Great Plains, USA.

    Science.gov (United States)

    Preston, Todd M; Kim, Kevin

    2016-10-01

    The Williston Basin in the Northern Great Plains has experienced rapid energy development since 2000. To evaluate the land cover changes resulting from recent (2000-2015) development, the area and previous land cover of all well pads (pads) constructed during this time were determined, the amount of disturbed and reclaimed land adjacent to pads was estimated, land cover changes were analyzed over time for three different well types, and the effects from future development were predicted. The previous land cover of the 12,990ha converted to pads was predominately agricultural (49.5%) or prairie (47.4%) with lesser amounts of developed (2.3%), aquatic (0.5%), and forest (0.4%). Additionally, 12,121ha has likely been disturbed and reclaimed. The area required per gas well remained constant through time while the land required per oil well increased initially and then decreased as development first shifted from conventional to unconventional drilling and then to multi-bore pads. For non-oil-and-gas wells (i.e. stratigraphic test wells, water wells, and injection wells), the area per well increased through time likely due to increased produced water disposal requirements. Future land cover change is expected to be 2.7 times greater than recent development with much of the development occurring in five counties in the core Bakken development area. Direct land cover change and disturbance from recent and expected development are predicted to affect 0.4% of the landscape across the basin; however, in the core Bakken development area, 2.3% of the landscape will be affected including 2.1% of the remaining grassland. Although future development will result in significant land cover change, evolving industry practices and proactive siting decisions, such as development along energy corridors and placing pads in areas previously altered by human activity, have the potential to reduce the ecological effects of future energy development in the Williston Basin. PMID:27318516

  1. The structure of the Chañarcillo Basin: An example of tectonic inversion in the Atacama region, northern Chile

    Science.gov (United States)

    Martínez, F.; Arriagada, C.; Peña, M.; Del Real, I.; Deckart, K.

    2013-03-01

    The Chañarcillo Basin is an Early Cretaceous extensional basin in northern Chile (27-29°S). The folding style of the syn-rift successions along the eastern side of the basin reveals an architecture consisting of a NNE-trending anticline “Tierra Amarilla Anticlinorium”, associated with the inversion of the Elisa de Bordos Fault. A set of balanced cross sections and palinspastic restorations across the basin show that a partially inverted “domino-style” half-graben as the structural framework is most appropriate for reproducing the deformation observed at the surface. This inverted system provides a 9-14 km shortening in the basin. The ages of the synorogenic deposits preserved next to the frontal limb of the “Tierra Amarilla Anticlinorium” suggest that basin inversion occurred close to the “K-T” boundary (“K-T” phase of Andean deformation). We propose that tectonic inversion is the fundamental deformation mechanism, and that it emphasizes the regional importance of inherent Mesozoic extensional systems in the evolution of the northern Chilean Andes.

  2. Crustal structure beneath the Northern Transantarctic Mountains and Wilkes Subglacial Basin: Implications for tectonic origins

    Science.gov (United States)

    Hansen, Samantha E.; Kenyon, Lindsey M.; Graw, Jordan H.; Park, Yongcheol; Nyblade, Andrew A.

    2016-02-01

    The Transantarctic Mountains (TAMs) are the largest noncollisional mountain range on Earth. Their origin, as well as the origin of the Wilkes Subglacial Basin (WSB) along the inland side of the TAMs, has been widely debated, and a key constraint to distinguish between competing models is the underlying crustal structure. Previous investigations have examined this structure but have primarily focused on a small region of the central TAMs near Ross Island, providing little along-strike constraint. In this study, we use data from the new Transantarctic Mountains Northern Network and from five stations operated by the Korea Polar Research Institute to investigate the crustal structure beneath a previously unexplored portion of the TAMs. Using S wave receiver functions and Rayleigh wave phase velocities, crustal thickness and average crustal shear velocity (V>¯s) are resolved within ±4 km and ±0.1 km/s, respectively. The crust thickens from ~20 km near the Ross Sea coast to ~46 km beneath the northern TAMs, which is somewhat thicker than that imaged in previous studies beneath the central TAMs. The crust thins to ~41 km beneath the WSB. V>¯s ranges from ~3.1-3.9 km/s, with slower velocities near the coast. Our findings are consistent with a flexural origin for the TAMs and WSB, where these features result from broad flexure of the East Antarctic lithosphere and uplift along its western edge due to thermal conduction from hotter mantle beneath West Antarctica. Locally, thicker crust may explain the ~1 km of additional topography in the northern TAMs compared to the central TAMs.

  3. Sedimentary response to orogenic exhumation in the northern rocky mountain basin and range province, flint creek basin, west-central Montana

    Science.gov (United States)

    Portner, R.A.; Hendrix, M.S.; Stalker, J.C.; Miggins, D.P.; Sheriff, S.D.

    2011-01-01

    Middle Eocene through Upper Miocene sedimentary and volcanic rocks of the Flint Creek basin in western Montana accumulated during a period of significant paleoclimatic change and extension across the northern Rocky Mountain Basin and Range province. Gravity modelling, borehole data, and geologic mapping from the Flint Creek basin indicate that subsidence was focused along an extensionally reactivated Sevier thrust fault, which accommodated up to 800 m of basin fill while relaying stress between the dextral transtensional Lewis and Clark lineament to the north and the Anaconda core complex to the south. Northwesterly paleocurrent indicators, foliated metamorphic lithics, 64 Ma (40Ar/39Ar) muscovite grains, and 76 Ma (U-Pb) zircons in a ca. 27 Ma arkosic sandstone are consistent with Oligocene exhumation and erosion of the Anaconda core complex. The core complex and volcanic and magmatic rocks in its hangingwall created an important drainage divide during the Paleogene shedding detritus to the NNW and ESE. Following a major period of Early Miocene tectonism and erosion, regional drainage networks were reorganized such that paleoflow in the Flint Creek basin flowed east into an internally drained saline lake system. Renewed tectonism during Middle to Late Miocene time reestablished a west-directed drainage that is recorded by fluvial strata within a Late Miocene paleovalley. These tectonic reorganizations and associated drainage divide explain observed discrepancies in provenance studies across the province. Regional correlation of unconformities and lithofacies mapping in the Flint Creek basin suggest that localized tectonism and relative base level fluctuations controlled lithostratigraphic architecture.

  4. Hydrothermal recrystallization of the Lower Ordovician dolomite and its significance to reservoir in northern Tarim Basin

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Discovered in S15 and some other wells, the Lower Ordovician in the northern Tarim Basin consists mainly of brown gray-dark gray very fine-fine crystalline dolomite, with a minor portion of locally light gray-white medium-coarse crystalline dolomite. Silicification can be observed in the medium-coarse dolomite, and some euhedral drusy quartz can also be found in pores and fractures of the dolomite. The homogenization temperature of the fluid inclusions in the medium-coarse dolomite is between 110 and 200°C with maximum between 140 and 190°C, and the salinity is between 10.7 and 18.5 wt.% NaCl Eq. The homogenization temperature and salinity of the fluid inclusions in the medium-coarse dolomite are similar to those in the drusy quartz. Compared with the very fine-fine dolomite, the medium-coarse phase contains relatively high Fe and Mn. The average concentration of FeO and MnO in the medium-coarse dolomite is 1.917% and 0.323%, respectively. The medium-coarse dolomite has a remarkable negative Eu anomaly, consistent with the REE pattern of the intermediate-felsic igneous rocks in the Tarim Basin. The oxygen isotopic composition of the medium-coarse dolomite is relatively lighter than that of the very fine-fine dolomite. The δ18OPDB values of the medium-coarse dolomite are between -10.35‰ and -7.31‰. The δ18OSMOW values of the fluid associated with the medium-coarse dolomite can be calculated according to homogenization temperature and oxygen isotope fractionation factor between dolomite and fluid, and the calculated values are between +4‰ and +10‰, consistent with those of the hydrothermal fluid. The medium-coarse dolomite has relatively high 87Sr/86Sr ratios as well, indi- cating an origin associated with intermediate-felsic igneous rock. The homogenization temperature, element composition, REE pattern, oxygen and strontium isotopes demonstrate that the medium-coarse dolomite is the result of recrystallization of very fine-fine dolomite under

  5. Seismic sequence and depositional evolution of slope basins in mid-northern margin of the South China Sea

    Institute of Scientific and Technical Information of China (English)

    LI Mingbi; JIN Xianglong; LI Jiabiao; DING Weiwei; FANG Yinxia; LIU Jianhua; TANG Yong

    2011-01-01

    As one of the biggest marginal seas in the western Pacific margin,the South China Sea (SCS) experienced continental riffing and seafloor spreading during the Cenozoic.The northern continental margin of the SCS is classified as a passive continental margin.However,its depositional and structural evolution remains controversial,especially in the deep slope area.The lack of data hindered the correlation between continental shelf and oceanic basin,and prevented the establishment of sequence stratigraphic frame of the whole margin.The slope basins in the mid-northern margin of SCS developed in the Cenozoic;the sediments and basin infill recorded the geological history of the continental margin and the SCS spreading.Using multi-channel seismic dataset acquired in three survey cruises during 1987 to 2004,combined with the data of ODP Leg 184 core and industrial wells,we carried out the sequence stratigraphic division and correlation of the Cenozoic in the middle-northern margin of SCS with seismic profiles and sedimentary facies.We interpreted the seismic reflection properties including continuity,amplitude,frequency,reflection terminals,and 15 sequence boundaries of the Cenozoic in the study area,and correlated the well data in geological age.The depositional environment changed from river and lake,shallow bay to open-deep sea,in correspondence to tectonic events of syn-rifting,early drifting,and late drifting stages of basin evolution.

  6. Radionuclide levels in fish from Lake Athabasca February 1993. Northern River Basins Study project report no.26

    International Nuclear Information System (INIS)

    The Northern River Basins Study was initiated through the 'Canada-Alberta-Northwest Territories Agreement Respecting the Peace-Athabasca-Slave River Basin Study, Phase II - Technical Studies' which was signed September 27, 1991. The purpose of the study is to understand and characterize the cumulative effects of development on the water and aquatic environment of the Study Area by coordinating with existing programs and undertaking appropriate new technical studies. This publication reports the method and findings of particular work conducted as part of the Northern River Basins Study. As such, the work was governed by a specific terms of reference and is expected to contribute information about the Study Area within the context of the overall study as described by the Study Final Report. This report has been reviewed by the Study Science Advisory Committee in regards to scientific content and has been approved by the Study Board of Directors for public release. It is explicit in the objectives of the Study to report the results of technical work regularly to the public. This objective is served by distributing project reports to an extensive network of libraries, agencies, organizations and interested individuals and by granting universal permission to reproduce the material. This report contains referenced data obtained from external to the Northern River Basins Study. Individuals interested in using external data must obtain permission to do so from the donor agency. (author). 47 refs., 9 tabs., 2 figs

  7. 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

    2016-01-01

    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 δ18O 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. PMID:27272610

  8. Oligocene-Miocene deformational and depositional history of the Andean hinterland basin in the northern Altiplano plateau, southern Peru

    Science.gov (United States)

    Perez, Nicholas D.; Horton, Brian K.

    2014-09-01

    Cenozoic basin fill of the northern Altiplano plateau records the tectonic development of the flanking Western Cordillera magmatic arc and Eastern Cordillera fold-thrust belt. The Ayaviri hinterland basin of southern Peru contains a ~2300 m thick succession of fluvial sandstones and overbank siltstones (upper Oligocene Puno Group and lower Miocene lower Tinajani Formation) capped by ~400 m of alluvial fan conglomerates (middle Miocene upper Tinajani Formation). New U-Pb zircon chronostratigraphic constraints from ~30 to 15 Ma yield sediment accumulation rates of 110-660 m/Myr. Newly dated growth strata highlight the genetic role played by thrust displacement in basin evolution. A several phase accumulation history derived from chronostratigraphic, provenance, and structural data reveals Oligocene basin filling by fluvial sand and mud that changes provenance from Western Cordillera Mesozoic-Cenozoic volcanic rocks to Paleozoic-Mesozoic Eastern Cordillera sedimentary rocks driven by deformation along the southwest directed, northeastern basin margin Ayaviri thrust at 28-26 Ma. Continued early Miocene fluvial deposition was sourced solely from the Eastern Cordillera. An abrupt middle Miocene shift to coarse alluvial fan deposition sourced from the Western Cordillera was driven by out-of-sequence deformation along the northeast directed, southwestern basin margin Pasani thrust at 18-16 Ma. This northern Altiplano out-of-sequence deformation was coincident with increased Eastern and Western Cordillera exhumation and thrusting and may be symptomatic of changes in critical wedge dynamics. The overall record of basin sedimentation and syndepositional fold-thrust deformation emphasizes the role of regional shortening in governing crustal thickening and basin evolution in the central Andes during the Oligocene to Miocene.

  9. Oligocene-miocene mammalian fossils from Hongyazi Basin and its bearing on tectonics of Danghe Nanshan in northern Tibetan plateau.

    Science.gov (United States)

    Li, Qiang; Wang, Xiaoming; Xie, Guangpu; Yin, An

    2013-01-01

    A shortage of Cenozoic vertebrate fossils in the Tibetan Plateau has been an obstacle in our understanding of biological evolution in response to changes in tectonism, topography, and environment. This is especially true for Paleogene records, so far known by only two sites along the northern rim of the Plateau. We report a Hongyazi Basin in northern Tibetan Plateau that produces at least three mammalian faunas that span Oligocene through late Miocene. Located at the foothills of the Danghe Nanshan and presently connected to the northern margin of the Suganhu Basin through the Greater Haltang River, the intermountain basin is controlled by the tectonics of the Danghe Nanshan to the north and Chahan'ebotu Mountain to the south, making the basin sediments well suited for inferring the evolutionary history of these two mountain ranges. At the bottom of the local section, the Oligocene Haltang Fauna is best compared to the early Oligocene Desmatolagus-Karakoromys decessus assemblage in the Dingdanggou Fauna in Tabenbuluk Basin. The Middle Miocene Ebotu Fauna from the middle Hongyazi section shares many taxa with the late Middle Miocene Tunggur mammal assemblage in Inner Mongolia, such as Heterosminthus orientalis, Megacricetodon sinensis, Democricetodon lindsayi, and Alloptox gobiensis. Toward the top of the section, the Hongyazi Fauna includes late Miocene elements typical of Hipparion faunas of North China. All three faunas are of typical North China-Central Asian characteristics, suggesting a lack of geographic barriers for faunal differentiation through the late Miocene. Sedimentary packages producing these faunas are arrayed from north to south in progressively younger strata, consistent with a compressive regime to accommodate shortening between Danghe Nanshan and Chahan'ebotu Mountain by thrust faults and folds. With additional constraints from vertebrate fossils along the northern flanks of the Danghe Nanshan, an eastward propagation of the Danghe Nanshan is

  10. Oligocene-miocene mammalian fossils from Hongyazi Basin and its bearing on tectonics of Danghe Nanshan in northern Tibetan plateau.

    Directory of Open Access Journals (Sweden)

    Qiang Li

    Full Text Available A shortage of Cenozoic vertebrate fossils in the Tibetan Plateau has been an obstacle in our understanding of biological evolution in response to changes in tectonism, topography, and environment. This is especially true for Paleogene records, so far known by only two sites along the northern rim of the Plateau. We report a Hongyazi Basin in northern Tibetan Plateau that produces at least three mammalian faunas that span Oligocene through late Miocene. Located at the foothills of the Danghe Nanshan and presently connected to the northern margin of the Suganhu Basin through the Greater Haltang River, the intermountain basin is controlled by the tectonics of the Danghe Nanshan to the north and Chahan'ebotu Mountain to the south, making the basin sediments well suited for inferring the evolutionary history of these two mountain ranges. At the bottom of the local section, the Oligocene Haltang Fauna is best compared to the early Oligocene Desmatolagus-Karakoromys decessus assemblage in the Dingdanggou Fauna in Tabenbuluk Basin. The Middle Miocene Ebotu Fauna from the middle Hongyazi section shares many taxa with the late Middle Miocene Tunggur mammal assemblage in Inner Mongolia, such as Heterosminthus orientalis, Megacricetodon sinensis, Democricetodon lindsayi, and Alloptox gobiensis. Toward the top of the section, the Hongyazi Fauna includes late Miocene elements typical of Hipparion faunas of North China. All three faunas are of typical North China-Central Asian characteristics, suggesting a lack of geographic barriers for faunal differentiation through the late Miocene. Sedimentary packages producing these faunas are arrayed from north to south in progressively younger strata, consistent with a compressive regime to accommodate shortening between Danghe Nanshan and Chahan'ebotu Mountain by thrust faults and folds. With additional constraints from vertebrate fossils along the northern flanks of the Danghe Nanshan, an eastward propagation of the

  11. Advances in ammonite biostratigraphy of the marine Atacama basin (Lower Cretaceous), northern Chile, and its relationship with the Neuquén basin, Argentina

    Science.gov (United States)

    Mourgues, Francisco Amaro

    2004-09-01

    Preliminary results about the Lower Cretaceous ammonite biostratigraphy of northern Chile reveal eight fossiliferous levels: Lower-Upper Valanginian neocomitid and olcostephanid faunas in the Punta del Cobre and Abundancia Formations and Upper Hauterivian-Barremian crioceratid in the Nantoco, Totoralillo, and Pabellón Formations. The faunal affinities with the Neuquén are strong during the Valanginian and Hauterivian. In contrast, during the Barremian and Aptian, the ammonites show affinities with Austral, California, and Tethys basinal faunas. The Lower Valanginian-lower Upper Aptian series in northern Chile comprises two sedimentary cycles separated by a regressive pulse of Upper Hauterivian-Lower Barremian age. This pulse may be equivalent to the regression that ended the Early Cretaceous marine cycle in central Chile and central west Argentina, where the second marine sedimentary cycle observed in northern Chile is not represented.

  12. Jurassic sedimentary evolution of southern Junggar Basin:Implication for palaeoclimate changes in northern Xinjiang Uygur Autonomous Region, China

    Institute of Scientific and Technical Information of China (English)

    Shun-Li Li; Xing-He Yu; Cheng-Peng Tan; Ronald Steel

    2014-01-01

    Junggar Basin, located in northern Xinjiang, presents continuous and multi-kilometer-thick strata of the Jurassic deposits. The Jurassic was entirely terrestrial lfuvial and lacustrine deltaic sedimentation. Eight outcrop sections across the Jurassic strata were meas-ured at a resolution of meters in southern Junggar Basin. Controlling factors of sedimentary evolution and palaeoclimate changes in Junggar Basin during the Jurassic were discussed based on lithology, fossils and tectonic setting. In the Early to Middle Jurassic, the warm and wide Tethys Sea generated a strong monsoonal circulation over the central Asian continent, and provided adequate moisture for Junggar Basin. Coal-bearing strata of the Badaowan, Sangonghe, and Xishanyao Formations were developed under warm and humid palaeocli-mate in Junggar Basin. In the late Middle Jurassic, Junggar Basin was in a semi-humid and semi-arid environment due to global warming event. Stratigraphy in the upper part of the Mid-dle Jurassic with less plant fossils became multicolor or reddish from dark color sediments. During the Late Jurassic, collision of Lhasa and Qiangtang Block obstructed monsoon from the Tethys Sea. A major change in climate from semi-humid and semi-arid to arid conditions took place, and reddish strata of the Upper Jurassic were developed across Junggar Basin.

  13. New seismo-stratigraphic data of the Volturno Basin (northern Campania, Tyrrhenian margin, southern Italy: implications for tectono-stratigraphy of the Campania and Latium sedimentary basins

    Directory of Open Access Journals (Sweden)

    Ennio Marsella

    2011-07-01

    Full Text Available A geological section of the Volturno Basin (northern Campania, continental margin, Italy has been constructed based on new multi-channel seismic data, to show the stratigraphic relationships between the filling in the Quaternary basin and the Meso-Cenozoic acoustic basement. The new seismic sections presented here outline the underlying structures of the basin and their relationships to the filling in the Quaternary basin. Deep exploration wells in Campania and Latium on the Tyrrhenian margin have gathered litho-stratigraphic and commercial multi-channel seismic data that can be used for better integration of the geological data for the area under study. The trending of the seismic units is controlled by the Massico Structural High, which forms the boundary of the Volturno Basin towards the north-west. This produces a geometry that is characteristic of a fan complex, with NE-SW trending. This qualitative calibration of the seismic sequences that fill the sedimentary basin was carried out through the litho-stratigraphic data of the «Castelvolturno 2» well, which highlights the pyroclastic layers and conglomeratic strata of the lagoon and delta environments as they evolve upwards towards marine sediments. Seismo-stratigraphic analysis shows the complex depositional geometries of the filling in the Volturno Basin, which overlie the Meso-Cenozoic carbonatic basement and the related flysch deposits. Coupled with regional geological evidence, the data interpretation here suggests that the Volturno Basin represents a half-graben structure that is characterized by down-thrown blocks along normal faults.

  14. Assessment of metallic mineral resources in the Humboldt River Basin, Northern Nevada, with a section on Platinum-Group-Element (PGE) Potential of the Humboldt Mafic Complex

    Science.gov (United States)

    Wallace, Alan R.; Ludington, Steve; Mihalasky, Mark J.; Peters, Stephen G.; Theodore, Ted G.; Ponce, David A.; John, David A.; and Berger, Byron R.; Zientek, Michael L.; Sidder, Gary B.; Zierenberg, Robert A.

    2004-01-01

    The Humboldt River Basin is an arid to semiarid, internally drained basin that covers approximately 43,000 km2 in northern Nevada. The basin contains a wide variety of metallic and nonmetallic mineral deposits and occurrences, and, at various times, the area has been one of the Nation's leading or important producers of gold, silver, copper, mercury, and tungsten. Nevada currently (2003) is the third largest producer of gold in the world and the largest producer of silver in the United States. Current exploration for additional mineral deposits focuses on many areas in northern Nevada, including the Humboldt River Basin.

  15. Development of Overpressure in the Tertiary Damintun Depression, Liaohe Basin, Northern China

    Institute of Scientific and Technical Information of China (English)

    YE Jiaren; HAO Fang; CHEN Jianyu

    2003-01-01

    The Damintun depression is one of the four depressions in the Liaohe basin in northern China, and is a rift basin developed in the Paleogene. This paper discusses in detail the characteristics of pressure and fluid potential of the Damintun depression based on a synthesis of the data from boreholes, well tests and seismic surveys. Data from sonic logs, well tests and seismic velocity measurements are used to study the pressure characteristics of the areas. From the sonic log data, shales can be characterized as normally pressured, slightly overpressured or highly overpressured; from the well test data, the pressure-depth gradient in oil-producing intervals implies hydrostatic pressure in general. Most seismic profiles in the Damintun depression are of sufficiently high quality for seismic velocities to be measured. The fluid pressures, excess pressures and pressure coefficients in 47 representative seismic profiles are predicted using formula calculation methods, and further transformed to fluid potentials. The resultant pressure profiles show normal pressure, moderate overpressure and intense overpressure increasing with depth. The pressure evolution can be divided into three stages as initial generation, partial dissipation and re-accumulation. Fluid potential is the principal factor controlling hydrocarbon migration in a reservoir. Its distribution varies with depth; above the T4 interface a gravity-flow dominates, whereas beneath it a compaction flow dominates. The development of overpressure in the Damintun depression has a crucial influence on the distribution of fluid potentials, which agrees with that of overpressure in general. The results of the fluid potential analysis indicate that the areas of Dongshenpu-Xinglongpu and the southwestern part of the depression are most favorable for hydrocarbon migration and accumulation.

  16. Seismic velocity structure of the Guerrero gap, Mexico

    OpenAIRE

    Jaime Domínguez; Gerardo Suárez; Diana Comte; Luis Quintanar

    2006-01-01

    A two-dimensional velocity structure of the Guerrero gap was obtained by applying a damped least square method to hypocenters of local seismicity recorded by a telemetric network situated on the Guerrero coast, above Cocos plate subduction zone. The region was parameterized by a mesh of 64 cubes in six layers, a total of 384 blocks. The results of 3-D inversion showed that differences of P-wave velocity values among blocks along the strike of the subduction zone were ~0.25 km/s, effectively s...

  17. Peat accumulation in drained thermokarst lake basins in continuous, ice-rich permafrost, northern Seward Peninsula, Alaska

    Science.gov (United States)

    Jones, Miriam C.; Grosse, Guido; Jones, Benjamin M.; Anthony, Katey Walter

    2012-01-01

    Thermokarst lakes and peat-accumulating drained lake basins cover a substantial portion of Arctic lowland landscapes, yet the role of thermokarst lake drainage and ensuing peat formation in landscape-scale carbon (C) budgets remains understudied. Here we use measurements of terrestrial peat thickness, bulk density, organic matter content, and basal radiocarbon age from permafrost cores, soil pits, and exposures in vegetated, drained lake basins to characterize regional lake drainage chronology, C accumulation rates, and the role of thermokarst-lake cycling in carbon dynamics throughout the Holocene on the northern Seward Peninsula, Alaska. Most detectable lake drainage events occurred within the last 4,000 years with the highest drainage frequency during the medieval climate anomaly. Peat accumulation rates were highest in young (50–500 years) drained lake basins (35.2 g C m−2 yr−1) and decreased exponentially with time since drainage to 9 g C m−2 yr−1 in the oldest basins. Spatial analyses of terrestrial peat depth, basal peat radiocarbon ages, basin geomorphology, and satellite-derived land surface properties (Normalized Difference Vegetation Index (NDVI); Minimum Noise Fraction (MNF)) from Landsat satellite data revealed significant relationships between peat thickness and mean basin NDVI or MNF. By upscaling observed relationships, we infer that drained thermokarst lake basins, covering 391 km2 (76%) of the 515 km2 study region, store 6.4–6.6 Tg organic C in drained lake basin terrestrial peat. Peat accumulation in drained lake basins likely serves to offset greenhouse gas release from thermokarst-impacted landscapes and should be incorporated in landscape-scale C budgets.

  18. Joint Interpretation of Magnetotellurics and Airborne Electromagnetics in the Rathlin Basin, Northern Ireland

    Science.gov (United States)

    Delhaye, Robert; Rath, Volker; Jones, Alan G.; Reay, Derek; The Iretherm Team

    2015-04-01

    In this study we present results from geophysical investigation of the sedimentary Rathlin Basin in Northern Ireland in order to assess the potential for low-to-medium enthalpy geothermal aquifers within the porous Permian and Triassic sandstone groups. The area and groups were identified as a potential geothermal resource due to the presence of both an elevated geothermal gradient (observed in two deep boreholes onshore) and favourable hydraulic properties (measured on core samples in the offshore part of the basin). Previous seismic experiments were not able to fully characterise the sediments beneath the overlying flood basalt. Complementing these earlier results, magnetotelluric data were acquired on a grid of 56 sites across the north-eastern portion of the onshore Rathlin Basin, and an additional 12 sites on the nearby Rathlin Island, in order to image the thickness, depth, and lateral continuity of the target sediments. Analysis and 3D modelling, including the effects of the highly conducting ocean, has been successful in deriving a resistivity model that maps the variation in the top of the sediments (base of the basalts) and the truncation of the basin sediments against the Tow Valley Fault, and gives a reasonable estimate of the thickness of the sediment fill. However, the resulting models show significant effects from distortion caused by near-surface inhomogeneities in the responses that cannot be resolved using the given frequency range and site density. Fortunately, for the area of Rathlin Basin, airborne electromagnetic data from the TELLUS project (http://www.bgs.ac.uk/gsni/tellus/contact/index.html) are available. These data were measured at four frequencies between 0.9 kHz and 25 kHz in a verical-coplanar loop configuration, with the dipole axis in flight direction. The spatial sampling distance was less than 25 m, with about 200 m distance between flight lines. Survey altitudes vary between 56 m and 244 m. Thus, for the top ˜100 m penetrated by

  19. Determination of faults parameters controlling the Petroleum Systems Elements in the northern North Sea by using 3D basin Modelling

    OpenAIRE

    Andriamihaja, Spariharijaona

    2011-01-01

    3D basin modelling of the northern North Sea region covering 4886km2 is performed in order to understand the petroleum system elements within the area. The approach used to obtain the most likely model is to analyze and determine quantitatively the faults properties controlling the hydrocarbons accumulations in the Gullfaks, Visund, Kvitebjørn, and Huldra fields. This approach is made by varying the faults properties defined by shale gauge ratio until the reserves in place in the four fields ...

  20. Trace fossils associated to the end-Messinian unconformity in the northern border of the Bajo Segura Basin (SE Spain)

    OpenAIRE

    Caracuel, Jesús Esteban; Corbí, Hugo; Estévez, Antonio; Giannetti, Alice; Monaco, Paolo; Pina, José Antonio; Soria, Jesús M.; Tent Manclús, José Enrique; Yébenes, Alfonso

    2009-01-01

    A detailed analysis of the Upper Messinian-Lower Pliocene at the northern border of the Bajo Segura Basin (BSB) has been carried out. Trace fossils of firm- and rockground were collected, aiding in the recognition of three ichnofacies: Glossifungites (types A and B), Entobia and Gnathichnus. The ichnological data provide evidence that the Pliocene flooding of the BSB, after the Messinian Salinity Crisis, was developed in two pulses. In the first one, the ingression penetrated only along the p...

  1. Digital resource modeling of the northern and central Appalachian Basin coal regions: Top producing coals

    Energy Technology Data Exchange (ETDEWEB)

    Ruppert, L.; Tewalt, S.; Bragg, L.; Wallack, R.; Jenkins, J.; Tully, J. [Geological Survey, Reston, VA (United States)

    1998-12-31

    The US Geological Survey is currently conducting a coal resource assessment of the coal beds and zones that are expected to provide the bulk of the Nation`s coal resources for the next few decades. In partnership with the state geologic surveys of Kentucky, Tennessee, West Virginia, Virginia, Pennsylvania, Ohio, and Maryland, six coal beds will be digitally assessed in the northern and central Appalachian Basin coal region. In ascending stratigraphic order, the beds which range from the Lower Pennsylvanian Pocahontas Formation to the Upper Pennsylvanian Monongahela Group are the Pocahontas No. 3, Pond Creek, Fire Clay, Lower Kittanning, Upper Freeport, and Pittsburgh coals. Comprehensive stratigraphic and geochemical databases have been developed for the coal beds. Maps that show the extent and mined areas of the beds, structure contour, isopach, and overburden thickness have been compiled for the Pittsburgh coal bed and are in preparation for the other coal beds. The resource model for the Pittsburgh coal bed indicates that of the original 33.6 billion short tons (30.5 billion tonnes) of Pittsburgh coal, approximately 15.9 billion short tons (14.4 billion tonnes) remain. The remaining coal is, however, higher in ash and sulfur, and generally thinner and under thicker overburden cover.

  2. Cross-fault pressure depletion, Zechstein carbonate reservoir, Weser-Ems area, Northern German Gas Basin

    Energy Technology Data Exchange (ETDEWEB)

    Corona, F.V.; Brauckmann, F.; Beckmann, H.; Gobi, A.; Grassmann, S.; Neble, J.; Roettgen, K. [ExxonMobil Production Deutschland GmbH (EMPG), Hannover (Germany)

    2013-08-01

    A cross-fault pressure depletion study in Upper Permian Zechstein Ca2 carbonate reservoir was undertaken in the Weser-Ems area of the Northern German Gas Basin. The primary objectives are to develop a practical workflow to define cross-fault pressures scenarios for Zechstein Ca2 reservoir drillwells, to determine the key factors of cross-fault pressure behavior in this platform carbonate reservoir, and to translate the observed cross-fault pressure depletion to fault transmissibility for reservoir simulation models. Analysis of Zechstein Ca2 cross-fault pressures indicates that most Zechstein-cutting faults appear to act as fluid-flow baffles with some local occurrences of fault seal. Moreover, there appears to be distinct cross-fault baffling or pressure depletion trends that may be related to the extent of the separating fault or fault system, degree of reservoir flow-path tortuosity, and quality of reservoir juxtaposition. Based on the above observations, a three-part workflow was developed consisting of (1) careful interpretation and mapping of faults and fault networks, (2) analysis of reservoir juxtaposition and reservoir juxtaposition quality, and (3) application of the observed cross-fault pressure depletion trends. This approach is field-analog based, is practical, and is being used currently to provide reliable and supportable pressure prediction scenarios for subsequent Zechstein fault-bounded drill-well opportunities.

  3. Salt-related structural styles of Kuqa foreland fold belt, northern Tarim basin

    Institute of Scientific and Technical Information of China (English)

    TANG; Liangjie; JIA; Chengzao; PI; Xuejun; CHEN; Suping; W

    2004-01-01

    The salt beds of Lower Tertiary developed in the mid-segment of Kuqa foreland fold belt, northern Tarim basin. They considerably controlled structural deformation of the belt.According to the field observation, seismic profile interpretation and drilling data, three different structural styles of supra-salt, intra-salt and sub-salt occurred in the Kuqa foreland fold belt. Supra-salt structural styles mainly include thrust faults and fault-related sags. Intra-slat structural styles essentially are salt-pillows, intra-salt faults and folds, and salt weld structures. Sub-salt structural styles mainly consist of imbricated thrust faults, duplex structures, pop-up and fault-related folds. It is indicated that great differences exist among supra-salt, intra-salt and sub-salt structures of Kuqa foreland fold belt. The salt-related structures were formed in the same structural stress field. The dynamic mechanism of the salt-related structures is mainly associated with gravitation, compression and plastic flow of salt beds.

  4. A Preliminary Study on the Red Beds in the Northern Heyuan Basin, Guangdong Province, China

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The red beds of the northern Heyuan Basin (Guangdong Province, China) are more than 4,000 m thick.Based on the lithological characters, in ascending order these beds are divided into the Dafeng Formation, Zhutian Formation, and Zhenshui Formation of the Nanxiong Group, Shanghu Formation and Danxia Formation. The Nanxiong Group with relatively mature coarse clastic rocks attains about 2 940 m in thickness. The Dafeng Formation is 837 m thick,consisting of conglomerates and sandy conglomerates; the Zhutian Formation, which is 1,200 m thick, consists of purplish red sandstone with gravels, poorly sorted sandstone, feldspathic quartzose sandstone banded granular conglomerate,siltstone, and sandy mudstone. The Zhutian Formation is rich in calcareous concretions. Heyuannia (Oviraptoridae) and turtle fossils were found in this formation. The Zhenshui Formation deposited to a thickness of 900 m consists of coarse sediments, including granular conglomerate, and gravelly sandstone with well developed cross-beddings; the Shanghu Formation, which is 820 m thick, consists of purplish red granular conglomerate coarse sandstone intercalated with fine siltstone; the Danxia Formation characterized by the Danxia landform is composed of coarse clastic gravels and sandy gravels. The lower part of the Nanxiong Group whence dinosaur eggs and derived oviraptorosaurs come, belongs to the Late Cretaceous. No fossils are found in the Shanghu Formation or the Danxia Formation, but their stratigraphic order of superposition on the Nanxiong Group clearly shows their younger age.

  5. Calculated Porosity of Volcanic Reservoir in Wangjiatun of the Northern Songliao Basin, NE China

    Institute of Scientific and Technical Information of China (English)

    Xuanlong Shan; Chuanbiao Wa; Rihui Cheng; Wanzhu Liu

    2003-01-01

    In Wangjiatun area of the Northern Songliao Basin, reservoir space can be divided into three types: primary pore, secondary pore and fissure according to their origins,which can be subdivided into eight subtypes: macro-vesicule,shrank primary vesicule, alteration pore, groundmass corrosive pore, normal structural crack, corrosive structural crack,filled structural crack and groundmass shrank crack according to texture and origin of the pore space. It has characteristic of double pore medium. Volcanic porosities of small diameter samples (with diameter of ca. 2.5 cm) and large diameter samples (with diameter of ca. 21.5 cm) were tested in accordance with the characteristic of volcanic reservoir space. Volcanic porosities for small diameter samples correspond with matrix porosities and those of large diameter samples correspond with total porosities including matrix and fractured porosities. Models of the calculated porosity by acoustic wave or density of volcanic reservoir are established in view of those measured data. Comparison of calculated and measuredporosities shows that precision of calculated porosities is lower for rhyolite and tuffites, and higher for basaltand andesite.Relative errors of calculated porosities by model of large diameter samples are lower than those of small diameter samples, i. e. precision of the former is higher than that of the later.

  6. Structural Evolution of the Eastern Qiulitagh Fold and Thrust Belt, Northern Tarim Basin, China

    Institute of Scientific and Technical Information of China (English)

    YANG Minghui; JIN Zhijun; LU Xiuxiang; SUN Dongsheng; TANG Xuan; PENG Gengxin; LEI Ganglin

    2009-01-01

    The eastern Qiulitagh fold and thrust belt (EQFTB) is part of the active Kuqa fold and thrust belts of the northern Tarirn Basin. Seismic reflection profiles have been integrated with surface geologic and drill data to examine the deformation and structure style of the EQFTB, particularly the deformational history of the Dina 2 gas field. Seismic interpretations suggest that Dongqiu 8 is overall a duplex structure developed beneath a passive roof thrust, which generated from a tipline in the Miocene Jidike Formation, and the sole thrust was initiated from the same Jidike Formation evaporite zone that extends westward beneath the Kuqatawu anticline. Dongqiu 5 is a pop-up structure at the western part of the EQFTB, also developed beneath the Jidike Formation evaporite. Very gentle basement dip and steep dipping topographic slope in the EQFTB suggest that the Jidike Formation salt provides effective decoupling. The strong deformation in the EQFTB appears to have developed further south, in an area where evaporite may be lacking. Since the Pliocene, the EQFTB has moved farther south over the evaporite and reached the Yaken area. Restoring a balanced cross-section suggests that the minimum shortening across the EQFTB is more than 7800 m. Assuming that this shortening occurred during the 5.3 Ma timespan, the shortening rate is approximately 1.47 ram/year.

  7. Geology and coal-bed methane resources of the northern San Juan Basin, Colorado and New Mexico

    International Nuclear Information System (INIS)

    This guidebook is the first of its kind: A focused look at coal-bed methane in a large Rocky Mountain Laramide basin. The papers in this volume cover every aspect of coal-bed methane in the San Juan Basin, including: The geology, environments of deposition, and geometry of the coal beds that contain the resource; the origin and migration history of the gas; basin-wide resource estimates; the engineering aspects of getting the gas out of the ground; the marketing and economics of producing coal-bed methane in the San Juan Basin; the legal ownership of the gas; state regulations governing well spacing and field rules; disposal of produced water; and land and mineral ownership patterns in the northern part of the basin. Also included are detailed papers on all of the major coal-bed methane fields in the basin, and in a paper on the history of Fruitland gas production, a discussion of most of the not-so-major fields. A small section of the book deals with geophysical methods, as yet still experimental, for surface detection of underground hydrocarbon resources. Individual papers have been processed separately for inclusion on the data base

  8. Precipitation thresholds for triggering floods in Corgo hydrographic basin (Northern Portugal)

    Science.gov (United States)

    Santos, Monica; Fragoso, Marcelo

    2016-04-01

    The precipitation is a major cause of natural hazards and is therefore related to the flood events (Borga et al., 2011; Gaál et al., 2014; Wilhelmi & Morss, 2013). The severity of a precipitation event and their potential damage is dependent on the total amount of rain but also on the intensity and duration event (Gaál et al., 2014). In this work, it was established thresholds based on critical combinations: amount / duration of flood events with daily rainfall data for Corgo hydrographic basin, in northern Portugal. In Corgo basin are recorded 31 floods events between 1865 and 2011 (Santos et al., 2015; Zêzere et al., 2014). We determined the minimum, maximum and pre-warning thresholds that define the boundaries so that an event may occur. Additionally, we applied these thresholds to different flood events occurred in the past in the study basin. The results show that the ratio between the flood events and precipitation events that occur above the minimum threshold has relatively low probability of a flood happen. These results may be related to the reduced number of floods events (only those that caused damage reported by the media and produced some type of damage). The maximum threshold is not useful for floods forecasting, since the majority of true positives are below this limit. The retrospective analysis of the thresholds defined suggests that the minimum and pre warning thresholds are well adjusted. The application of rainfall thresholds contribute to minimize possible situations of pre-crisis or immediate crisis, reducing the consequences and the resources involved in emergency response of flood events. References Borga, M., Anagnostou, E. N., Blöschl, G., & Creutin, J. D. (2011). Flash flood forecasting, warning and risk management: the HYDRATE project. Environmental Science & Policy, 14(7), 834-844. doi: 10.1016/j.envsci.2011.05.017 Gaál, L., Molnar, P., & Szolgay, J. (2014). Selection of intense rainfall events based on intensity thresholds and

  9. The Post-Permian evolution of the Northern Part of the North German Basin

    Science.gov (United States)

    Hansen, M. B.; Huebscher, C.; Lykke-Andersen, H.; Gajewski, D.; Dehghani, A.; Reicherter, K.

    2004-12-01

    In the frame of the Priority Program 1135 of the German Research Foundation (DFG) "Dynamics of sedimentary systems under varying stress conditions by example of the Central European Basin System", the scientific goal of the NeoBaltic project is to describe the post-Permian to recent geological evolution of the entire western Baltic Sea region, with a special emphasis on neotectonic activity and it relation to salt dynamics. The western Baltic Sea comprises the northern part of the North German Basin (NGB), a part of the Central European Basin System (CEBS), and the transitional zone between the NGB and the Baltic Shield. In order to investigate these scientific goals the Universities of Aarhus (Denmark) and Hamburg (Germany) has since 1998 completed seven marine campaigns in the western Baltic Sea, collecting 2D high resolution seismic (HRS), gravity and magnetic data in the entire region during different projects. Since 2003 all these data has been available for the NeoBaltic project. All together the data pool have more than 7000 km HRS, 5000 km gravity and 4000 km magnetic data. Until now the project work has been focused on the completion of the data processing and the digital interpretation of important Mesozoic and Cenozoic markers on the seismic sections from the Bays of Kiel and Mecklenburg. Furthermore, several maps have been completed from the potential field data (gravity and magnetic). As a result of the digital interpretation of the HRS data, the overall geological evolution of the northern part of the NGB can be subdivided into four distinct periods. During the Triassic and the Early Jurassic, E-W extension and the deposition of clastic sediments initiated the movement of the underlying Zechstein evaporites. This is seen by the presence of several salt pillows in the region. The deposition ceased during the Middle Jurassic, when the entire area was uplifted, due to the Mid North Sea Doming. The uplift resulted in a pronounced erosion of Upper Triassic

  10. Acapulco, Guerrero through the ages / Acapulco, Guerrero a través de los siglos

    Directory of Open Access Journals (Sweden)

    Erika Patricia Cárdenas Gómez

    2016-09-01

    Full Text Available This article aims to present brief history of one of the most important cities and ports of Mexico, it is Acapulco, Guerrero. The period under review comprises the year 1567 to 2014. In this period urban settlement that has been disrupted by several processes, economic, social and political aspects of international and national character that must be analyzed. This is done from available cartographic material, which is comple- mented by bibliographical, documentary and statistical information. Also, the observations made by the Malaspina expedition, Humboldt and Ratzel are retaken. While it is true the issue has already been presented by several authors, the contribution of this article is that the exercise is updated. El presente artículo tiene como objetivo presentar una breve historia de una de las ciudades y puertos más importantes de México, se trata de Acapulco, Guerrero. El periodo que se analiza comprende del año de 1567 al 2014. En este lapso de tiempo dicho asentamiento urbano ha sido trastocado por varios procesos, económicos, sociales y políticos de carácter internacional y nacional que es necesario analizar. Ello se hace a partir del material cartográfico disponible, el cual se complementa con información bibliográfica, documental y estadística. Asimismo, se retoman las observaciones hechas por la expedición de Malaspina, Humboldt y Ratzel. Si bien es cierto la temática ya ha sido presentada por varios autores, el aporte de este artículo radica en que el ejercicio está actualizado.

  11. Timing, distribution, amount, and style of Cenozoic extension in the northern Great Basin

    Science.gov (United States)

    Henry, Christopher D.; McGrew, Allen J.; Colgan, Joseph P.; Snoke, Arthur W.; Brueseke, Matthew E.

    2011-01-01

    This field trip examines contrasting lines of evidence bearing on the timing and structural style of Cenozoic (and perhaps late Mesozoic) extensional deformation in northeastern Nevada. Studies of metamorphic core complexes in this region report extension beginning in the early Cenozoic or even Late Cretaceous, peaking in the Eocene and Oligocene, and being largely over before the onset of “modern” Basin and Range extension in the middle Miocene. In contrast, studies based on low-temperature thermochronology and geologic mapping of Eocene and Miocene volcanic and sedimentary deposits report only minor, localized extension in the Eocene, no extension at all in the Oligocene and early Miocene, and major, regional extension in the middle Miocene. A wealth of thermochronologic and thermobarometric data indicate that the Ruby Mountains–East Humboldt Range metamorphic core complex (RMEH) underwent ~170 °C of cooling and 4 kbar of decompression between ca. 85 and ca. 50 Ma, and another 450 °C cooling and 4–5 kbar decompression between ca. 50 and ca. 21 Ma. These data require ~30 km of exhumation in at least two episodes, accommodated at least in part by Eocene to early Miocene displacement on the major west-dipping mylonitic zone and detachment fault bounding the RMEH on the west (the mylonitic zone may also have been active during an earlier phase of crustal extension). Meanwhile, Eocene paleovalleys containing 45–40 Ma ash-flow tuffs drained eastward from northern Nevada to the Uinta Basin in Utah, and continuity of these paleovalleys and infilling tuffs across the region indicate little, if any deformation by faults during their deposition. Pre–45 Ma deformation is less constrained, but the absence of Cenozoic sedimentary deposits and mappable normal faults older than 45 Ma is also consistent with only minor (if any) brittle deformation. The presence of ≤1 km of late Eocene sedimentary—especially lacustrine—deposits and a low-angle angular

  12. Asynchronous timing of extension and basin formation in the South Rhodope core complex, SW Bulgaria, and northern Greece

    Science.gov (United States)

    Stübner, Konstanze; Drost, Kerstin; Schoenberg, Ronny; Böhme, Madelaine; Starke, Jessica; Ehlers, Todd A.

    2016-01-01

    Upper crustal extensional structures range from steep normal faults to shallow-dipping detachments. The relationship between extension and formation of synkinematic hanging wall basins including their relative timing is not well understood. The South Rhodope core complex, Southern Balkans, has experienced extension for >40 Ma leading to a number of extensional structures and Cenozoic sedimentary basins. We present new bedrock and basin detrital zircon and apatite (U-Th-Sm)/He ages from the Pirin and Rila Mountains and the Sandanski basin. Results identify three episodes of Cenozoic extension in SW Bulgaria accommodated by (1) the Eocene/Oligocene Mesta detachment; (2) the early to middle Miocene Gorno Spanchevo fault (circa 18-15 Ma), which is the northern prolongation of the Strymon low-angle detachment; and (3) the late Miocene West Pirin fault (≤10 Ma). Detachment faulting on the Strymon fault accommodated tens of kilometers of ENE-WSW extension and created ~1500 m topographic relief, but because the resulting hillslopes were gentle (≤10°), extension did not lead to enhanced footwall erosion or formation of a hanging wall basin. In contrast, the West Pirin normal fault resulted in mostly vertical motion of its footwall causing steep topography, rapid erosion, and formation of the synrift Sandanski basin. Digital topographic analysis of river channel profiles identifies the latest episodes of deformation including westward tilting of the Sandanski and Strymon basins and Quaternary N-S extension. This study demonstrates that basin formation in the South Rhodope core complex is related to normal faulting postdating the main episode of crustal stretching by detachment faulting.

  13. Digital model of the seabed geomorphology of southern-central Espirito Santo basin and northern Campos basin; Modelo digital da geomorfologia do fundo oceanico do centro-sul da bacia do Espirito Santo e norte da bacia de Campos

    Energy Technology Data Exchange (ETDEWEB)

    Schreiner, Simone; Souza, Mariana Beatriz Ferraz Mendonca de; Migliorelli, Joana Paiva Robalo [Petroleo Brasileiro S. A. (PETROBRAS), Rio de Janeiro, RJ (Brazil). Unidade de Servicos de Exploracao e Producao], Emails: schreiner@petrobras.com.br, mbfms.fototerra@petrobras.com.br, joanamigli.fototerra@petrobras.com.br

    2009-05-15

    That communication brings the result of a bathymetric mosaic of converted in a digital model of the ocean topography, consisting of 17 seismic projects 3D, besides 17 multibeam bathymetry surveys of South-Central Espirito Santo Basin and Northern Campos Basin.

  14. Depositional and provenance record of the Paleogene transition from foreland to hinterland basin evolution during Andean orogenesis, northern Middle Magdalena Valley Basin, Colombia

    Science.gov (United States)

    Moreno, Christopher J.; Horton, Brian K.; Caballero, Victor; Mora, Andrés; Parra, Mauricio; Sierra, Jair

    2011-10-01

    The Central Cordillera and Eastern Cordillera of the northern Andes form the topographic flanks of the north-trending Magdalena Valley Basin. Constraining the growth of these ranges and intervening basin has implications for Andean shortening and the transformation from a foreland to hinterland basin configuration. We present sedimentological, paleocurrent, and sandstone petrographic results from Cenozoic type localities to provide insights into the tectonic history of the northern Middle Magdalena Valley Basin of Colombia. In the Nuevo Mundo Syncline, the mid-Paleocene transition from marine to nonmarine deposystems of the Lisama Formation corresponds with a paleocurrent shift from northward to eastward transport. These changes match detrital geochronological evidence for a contemporaneous shift from cratonic (Amazonian) to orogenic (Andean) provenance, suggesting initial shortening-related uplift of the Central Cordillera and foreland basin generation in the Magdalena Valley by mid-Paleocene time. Subsequent establishment of a meandering fluvial system is recorded in lower-middle Eocene strata of the lower La Paz Formation. Eastward paleocurrents in mid-Paleocene through uppermost Eocene fluvial deposits indicate a continuous influence of western sediment source areas. However, at the upper middle Eocene (˜40 Ma) boundary between the lower and upper La Paz Formation, sandstone compositions show a drastic decrease in lithic content, particularly lithic volcanic fragments. This change is accompanied by a facies shift from mixed channel and overbank facies to thick, amalgamated braided fluvial deposits of possible fluvial megafans, reflecting changes in both the composition and proximity of western sediment sources. We attribute these modifications to the growing influence of exhumed La Cira-Infantas paleohighs in the axial Magdalena Valley, features presently buried beneath upper Eocene-Quaternary basin fill along the western flank of the Nuevo Mundo Syncline. In

  15. The architecture of an incipient oceanic basin: a tentative reconstruction of the Jurassic Liguria-Piemonte basin along the Northern Apennines-Alpine Corsica transect

    Science.gov (United States)

    Marroni, Michele; Pandolfi, Luca

    2007-11-01

    In this paper, a scenario for the early evolution of the Jurassic oceanic Liguria-Piemonte basin is sketched. For this purpose, four selected examples of ophiolite sequences from the Northern Apennines and Corsica are described and analyzed. In the External Ligurian units (Northern Apennines), the ocean-continent transition of the Adria plate was characterized by a basement made up of subcontinental mantle and lower continental crust, covered by extensional allochthons of upper crust. Both, the basement rocks and the extensional allochthons are cut by basaltic dikes and covered by basalts and pelagic deposits. The conjugate ocean-continent transition of the Corsica margin, represented by the Balagne nappe (Corsica), was composed of mantle peridotites and gabbros covered by basaltic flows and minor breccias, that in addition include continent-derived clasts. By contrast, the innermost (i.e., closest to the ocean) preserved area observed in the Internal Ligurian (Northern Apennines) and Inzecca (Corsica) units consists of former morphological highs of mantle peridotites and gabbros, bordered by small basins where the basement is covered by a volcano-sedimentary complex, characterized by ophiolitic breccias and cherts interlayered with basaltic flows. The overall picture resulting from our reconstructions suggests an asymmetric architecture for the Liguria-Piemonte basin with a central area bounded by two different transition zones toward the continental margins. This architecture can be interpreted as the result of a rifting process whose development includes a final stage characterized by passive, asymmetric extension of the lithosphere along an east-dipping detachment fault system.

  16. (Guerrero, México (parte A

    Directory of Open Access Journals (Sweden)

    Arturo García Romero

    2005-01-01

    Full Text Available En la actualidad existe un amplio interés por el valor del paisaje como una alternativa de análisis ambiental, sin embargo, esta aproximación ha sido poco utilizada en los ecosistemas de México. El objetivo de este estudio fue determinar el valor del paisaje en la selva baja caducifolia (SBC de la cuenca baja del río Papagayo, Guerrero, México. Se realizó una clasificación jerárquica de paisajes y se aplicó un índice de valor del paisaje basado en cuatro indicadores: sensibilidad de laderas, fragmentación, calidad visual y significado social. Los resultados indican que el área está constituida por tres sistemas de paisajes –montañas, lomeríos y llanura aluvial– definidos por cambios morfo-litológicos y bioclimáticos; 17 subsistemas de paisajes y 16 paisajes elementales, definidos por los tipos de vegetación, usos de suelo y niveles de perturbación. El valor del paisaje fue heterogéneo, aunque tiende a ser mayor en los subsistemas montañosos de selvas y bosques, debido a que son más inaccesibles, por lo que el significado social y los niveles de perturbación y fragmentación se reducen. En contraste, los subsistemas de lomeríos con selva baja caducifolia tienen alto significado social debido a la cercanía y accesibilidad, lo cual favorece la intensificación de los usos del suelo, el incremento de la fragmentación y la caída de la calidad visual y del valor natural del paisaje. Si bien, la vegetación secundaria de la SBC (acahual ha sido valorada por su importancia en los mecanismos de regeneración de las selvas, en este caso obtuvo un valor reducido debido a la intensidad en el manejo de recursos, tanto en el pastoreo, como en la extracción de leña y la producción de carbón. El método implementado en este estudio permite sintetizar el balance entre la degradación ambiental y los caracteres de la apropiación cultural del paisaje en escalas geográficas amplias.

  17. estado de Guerrero, México

    Directory of Open Access Journals (Sweden)

    José Ramón Hernández Santana

    2005-01-01

    Full Text Available En este trabajo se presentan las principales regularidades del plano morfoestructural de los tercios medio e inferior de las cuencas hidrográficas de los ríos Papagayo y Sabana, en el estado de Guerrero, el cual se formó durante la etapa neotectónica (N - Q del desarrollo del relieve, en un diseño de bloques positivos y negativos, que han heredado la estructura interna de los diferentes complejos litológicos presentes y de sus deformaciones tectónicas antiguas, determinando la presencia de morfoestructuras masivas, sobre basamento granítico; morfoestructuras de bloques en plegamientos y monoclinales sobre rocas terrígenas y mantos calcáreos; morfoestructuras caóticas sobre depósitos gravitacionales; morfoestructuras en depósitos jóvenes no consolidados; y otros tipos. La neotectónica ha sido diferenciada, determinando diferentes ascensos durante la etapa que determinan un complicado mosaico de diversos estilos de fracturamiento, sobre los cuales se sobreponen los diseños de las foliaciones graníticas y metamórficas, como expresión tectónicamente pasiva de la litología. Finalmente, la tipología estructuro-geomorfológica arrojó la presencia de 32 tipos de morfoestructuras, ocho en montañas medias, ocho en montañas bajas, siete en premontañas, cuatro en lomeríos y cinco en llanuras, desarrolladas en cinco basamentos geológicos con cuatro niveles de expresión litomorfoestructural. Estos bloques morfoestructurales encuentran relación en varias comunidades geotectónicas de interrelación interbloques neotectónicos: sistema irregular de bloques; sistema de horst triangulares escalonados, en transcurrencias; sistema isométrico de bloques escalonados; sistema asimétrico alterno de horst y graben; sistema de bloques escalonados en litomorfoestructuras circulares; sistema de litomorfoestructuras circulares en bóveda; entre otros.

  18. Crustal Structure and Extension from Slope to Deepsea Basin in the Northern South China Sea

    Institute of Scientific and Technical Information of China (English)

    Hu Dengke; Zhou Di; Wu Xiangjie; He Min; Pang Xiong; Wang Yuwei

    2009-01-01

    The newly acquired long-cable multi-channel seismic (MCS) lines were used to study the crustal structure and extension in an NW-SE elongated 150 km by 260 Van strip from the slope to the deepsea basin in the northern South China Sea (SCS).These profdes are of good penetration that Moho is recognizable in ~70% length of the lines.Seismostrattgraphic interpretation and time-depth conversion were conducted.A power function D = atb+ c was used in the time-depth conversion,which avoided the under-or over-estimation of the depths of deep-seated interfaces by cubic or quadratic polynomial functions.Contour maps of basement depth,Moho depth,crustal thickness,and crustal stretching factor were obtained for the study area.In the dip direction,the Moho depth decreases stepwisely from 28 km in the outer shelf southwards to 19,15,and 12 km in the deepsea basin,with ramps at the shelf break,lower slope,and the continent ocean boundary (COB),respectively.Accordingly,the crustal thickness decreased southwards from 3,and 7 km spectively.Under the center of the Balynn (白云) sag,the crust thins significantly to < 7 kin.The crustal stretching factor βc was calculated by assuming the original crust thickness of 30 km.In the centers of the Baiyun sag,βc exceeds 5.Tertiary and Quaternary volcanic activities show a general trend of intensifying towards the COB.An important finding of this study is the along-strike variation of the crustal structure.A Moho rise extends from the COB NW-ward until the shelf break,about 170 km long and 50-100 km wide,with Moho depth < 20 kin.This is called the Balyun Moho Nose,which is bounded to the east,west,and north by belts of high Moho gradients indicative of crustal or even lithospheric faults.The doming of Moho in the nose area might he the cause of the W-E segmentation of the crustal and geological structures along the slope of the northern South China Sea,and the cause of the strong crustal

  19. Upper Pliocene Diatom Record From Northern Basin, Ross Sea; Potential Correlation to Other Antarctic Continental Shelf Records

    Science.gov (United States)

    Sjunneskog, C.; Bart, P.; Chow, J.; Winter, D.; Scherer, R.; Andrill Mis Project Science Team

    2007-12-01

    The Northern Basin seismic record suggests a dynamic East Antarctic Ice Sheet with at least eight Late Neogene glacial expansions. The seismic-stratigraphic record indicates relatively thick late Neogene sequences on the outer continental shelf and upper slope and possibly undisturbed interglacial sequences. In 2003 Nathaniel B. Palmer (NBP03-01) collected 10 piston and jumbo piston cores in a depth transect from Mawson Bank to Drygalski Basin. The sediment cores range from 46 cm to over 4 meters in length, only recovering the surface of upper seismic unit. The lithologies of the cores include diatom mud, bioclastic sediment, silt, sand, clay and diamicton. Diatom analyses reveals that two of these cores, NBP03-01 PC2 and NBP03-01 PC8, have penetrated into undisturbed Upper Pliocene sequences. Upper Pliocene diatomaceous units are also recovered in Prydz Bay ODP sites 742 age ca. 1.8-2.2 Ma, and 1166 ages ca 1.8-2.2 and 2.5-2.8, sandwiched between diamictons. Recovery of Pliocene and Pleistocene sediment records of interglacial events is rare on the Antarctic continental shelf and the obtained records have been difficult to correlate with any certainty. With the recent recovery of the ANDRILL MIS (AND-1 core) the potential for correlation of these records has improved significantly. The sediment record from ANDRILL MIS comprises 13 diatomaceous units, all with their own specific diatom assemblage and key species. Comparison of diatom assemblages using key taxa and PCA show a strong correlation between Northern Basin PC2 and PC8, ODP Site 742 and MIS diatom unit IV placed at the Gauss-Matuyama boundary. Continued multiproxy analyses and independent dating will be performed to further constrain the correlation. The initial results have implications for regional correlation of interglacial events, and suggest that other Pliocene sediment records may be preserved in the Northern Basin region.

  20. Palaeoclimatic oscillations in the Pliensbachian (Early Jurassic) of the Asturian Basin (Northern Spain)

    Science.gov (United States)

    Gómez, Juan J.; Comas-Rengifo, María J.; Goy, Antonio

    2016-05-01

    One of the main controversial themes in palaeoclimatology involves elucidating whether climate during the Jurassic was warmer than the present day and if it was the same over Pangaea, with no major latitudinal gradients. There has been an abundance of evidence of oscillations in seawater temperature throughout the Jurassic. The Pliensbachian (Early Jurassic) constitutes a distinctive time interval for which several seawater temperature oscillations, including an exceptional cooling event, have been documented. To constrain the timing and magnitude of these climate changes, the Rodiles section of the Asturian Basin (Northern Spain), a well exposed succession of the uppermost Sinemurian, Pliensbachian and Lower Toarcian deposits, has been studied. A total of 562 beds were measured and sampled for ammonites, for biochronostratigraphical purposes, and for belemnites, to determine the palaeoclimatic evolution through stable isotope studies. Comparison of the recorded latest Sinemurian, Pliensbachian and Early Toarcian changes in seawater palaeotemperature with other European sections allows characterization of several climatic changes that are likely of a global extent. A warming interval partly coinciding with a δ13Cbel negative excursion was recorded at the Late Sinemurian. After a "normal" temperature interval, with temperatures close to average values of the Late Sinemurian-Early Toarcian period, a new warming interval containing a short-lived positive δ13Cbel peak, developed during the Early-Late Pliensbachian transition. The Late Pliensbachian represents an outstanding cooling interval containing a δ13Cbel positive excursion interrupted by a small negative δ13Cbel peak. Finally, the Early Toarcian represented an exceptional warming period, which has been pointed out as being responsible for the prominent Early Toarcian mass extinction.

  1. Biomarkers of contaminant exposure in northern pike (Esox lucius) from the Yukon River Basin, Alaska

    Science.gov (United States)

    Hinck, J.E.; Blazer, V.S.; Denslow, N.D.; Myers, M.S.; Gross, T.S.; Tillitt, D.E.

    2007-01-01

    As part of a larger investigation, northern pike (n = 158; Esox lucius) were collected from ten sites in the Yukon River Basin (YRB), Alaska, to document biomarkers and their correlations with organochlorine pesticide (total p,p'-DDT, total chlordane, dieldrin, and toxaphene), total polychlorinated biphenyls (PCBs), and elemental contaminant (arsenic, cadmium, copper, lead, total mercury, selenium, and zinc) concentrations. A suite of biomarkers including somatic indices, hepatic 7-ethoxyresorufin O-deethylase (EROD) activity, vitellogenin concentrations, steroid hormone (17B- ustradiol and 16-kebtestosteront) concentrations, splenic macrophage aggregates (MAs), oocyte atresia, and other microscopic anomalies in various tissues were documented in YRB pike. Mean condition factor (0.50 to 0.68), hepatosomatic index (1.00% to 3.56%), and splenosomatic index (0.09% to 0.18%) were not anomalous at any site nor correlated with any contaminant concentration. Mean EROD activity (0.71 to 17.51 pmol/min/mg protein) was similar to basal activity levels previously measured in pike and was positively correlated with selenium concentrations (r = 0.88, P 63 ng/g), and MA-% values in female pike (0.24% to 0.54%) were lower than in male pike (0.32% to 0.75%) at similar PCB concentrations. Greater numbers of MAs were found as zinc concentrations increased in YRB female pike, but it is unlikely that this is a causative relationship. Histological abnormalities observed in gill, liver, spleen, and kidney tissues were not likely a result of contaminant exposure but provide information on the general health of YRB pike. The most common histologic anomalies were parasitic infestations in various organs and developing nephrons and nephrocalcinosis in posterior kidney tissues. Overall, few biomarker responses in YRB pike were correlated with chemical contaminant concentrations, and YRB pike generally appeared to be healthy with no site having multiple anomalous biomarker responses. ?? 2007

  2. Methane hydrate-bearing sediments in the Terrebonne basin, northern Gulf of Mexico

    Science.gov (United States)

    Meazell, K.; Flemings, P. B.

    2015-12-01

    We characterize the geological, geophysical, and thermodynamic state of three dipping, hydrate-bearing sands in the Terrebonne mini basin of the northern Gulf of Mexico, and describe three potential drilling locations to sample these hydrate reservoirs. Within the sand bodies, there is a prominent negative polarity seismic reflection (opposite phase to the seafloor reflector) that we interpret to record the boundary between gas hydrate above and free gas below. This anomaly is the Bottom Simulating Reflector (BSR) and the base of the Gas Hydrate Stability Zone (BGHSZ). Above the BSR, reflection seismic data record these reservoirs with a positive polarity while below it, they record the reservoirs with a negative polarity event. Within the sand bodies, seismic amplitudes are generally strongest immediately above and below the BSR and weaken in updip and downdip directions. Beneath the BSR, two of the reservoirs have a strong negative amplitude event that parallels structure that we interpret to record a gas-water contact, while the third reservoir does not clearly record this behavior. Much like the seafloor, the BSR is bowl-shaped, occurring at greatest depths in the northwest and rising near salt bodies in the south and east. In the north east area of previous exploration, the BSR is found at a depth of 2868 meters below sealevel, implying a geothermal gradient of 20.1oC/km for type I hydrates. Logging while drilling data reveal that the sands are composed of numerous thin, hydrocarbon-charged, coarse-grained sediments. Hydrate saturation in these sands is greatest near the BGHSZ. Pressure coring is proposed for three wells that will penetrate the reservoirs at different structural elevations in order to further elucidate reservoir conditions of the sands.

  3. A review of tectonics and sedimentation in a forearc setting: Hellenic Thrace Basin, North Aegean Sea and Northern Greece

    Science.gov (United States)

    Maravelis, A. G.; Boutelier, D.; Catuneanu, O.; Seymour, K. St.; Zelilidis, A.

    2016-04-01

    Exposure of the forearc region of the North Aegean Sea, Greece, offers insight into evolving convergent margins. The sedimentary fill of the Thrace Basin during the Late Eocene to Oligocene time provides a record of subduction-driven processes, such as growth of magmatic arcs and construction of accretionary complexes. This large sediment repository received sediment from two sources. The southern (outboard) basin margin reflects the active influence of the exhumed accretionary prism (e.g. Pindic Cordillera or Biga peninsula), while the northern (inboard) margin records the effect of the magmatic arc in the Rhodope region. The forearc basin sedimentary fills shoal upward into shallow-marine strata but are dominated mainly by deep-marine facies. The depositional trend and stacking pattern are dominated by progradational patterns. This trend, which is observed in both basin margins, is related to tectonic deformation rather than sea-level fluctuations. Additional evidence for this tectonic uplift comes from the backstripping analysis. The accretionary complex provided material into the forearc basin. This material was transported northeast and formed a sand-rich turbidity system that evolved upslope into shallow-marine deposits. Stratigraphic data indicate that this turbidity system exhibits a successive landward (inboard) migration of the depocenter. Provenance data utilizing sandstone petrography, conglomerate clast composition, and bulk-rock geochemistry suggest that this system reflects an increased influx of mafic material into the basin. Volcanic arc-derived material was transported south and east and accumulated in deep-marine settings. Both stratigraphic and provenance data indicate a seaward (outboard) migration of the basin depocenter and a significant increase in felsic detritus into the forearc.

  4. Stress state variations among the clay and limestone formations of the molasse basin of Northern Switzerland

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. Full text of publication follows: The design of geological repositories for radioactive waste responds to the requirements of technical feasibility and long-term safety in the context of a specific geological setting. An important aspect of the geological setting is the primary stress field. To a large extent the stress state controls repository induced effects such as the excavation damage zone and the associated potential changes in the waste isolation properties of the host rock. Therefore the measurement of the stress state receives some attention where the site selection for geological repositories focuses onto relatively weak host rocks such as clay-stones and marly shales that tend to develop a significant excavation damage zone. Measurements of the minimum stress magnitudes in a recently drilled geothermal well in the Molasse Basin of northern Switzerland have yielded a stress profile reaching from 592 m to 1455 m depth. It straddles several rock units and includes the top of the crystalline basement. The sedimentary sequence consists of Marine limestones, shales and marls unconformably covered by Tertiary rocks of the Molasse. In other parts of the basin the evaporitic rocks of the Triassic Muschelkalk formation at the base of the sedimentary layer served as a regional detachment and enabled thin skinned thrusting and the formation of the Jura Fold and Thrust Belt in the Late Miocene. The stress measurements have been performed in the open hole by Mini-frac tests. The method uses a double packer system to isolate a one meter long interval of the borehole that is then pressurized at high injection rates up to the breakdown of the formation. Repeated pressurization of the interval allows to determine the stress that acts on the newly created fracture. The total injected volume during such a test is in the range of a few litres and the size of the fracture that extends from the borehole normal to the minimum

  5. Thermal-rheological structure of lithosphere beneath the northern flank of Tarim Basin, western China:Implications for geodynamics

    Institute of Scientific and Technical Information of China (English)

    LIU; Shaowen; WANG; Liangshu; LI; Cheng; LI; Hua; HAN; Yong

    2004-01-01

    Based on the data of geo-temperature and thermophysical parameters of rocks in the Kuqa Depression and the Tabei Uplift, northern flank of the Tarim Basin, in terms of the analytical solution of 1-D heat transfer equation, the thermal structure of the lithosphere under this region is determined. Our results show that the average surface heat flow of the northern flank of the Tarim Basin is 45 mW/m2, and the mantle heat flow is between 20 and 23 mW/m2; the temperature at crust-mantle boundary (Moho) ranges from 514℃ to 603℃ and the thermal lithosphere where the heat conduction dominates is 138-182 km thick. Furthermore, in combination with the P wave velocity structure resulting from the deep seismic sounding profile across this region and rheological modeling, we have studied the local composition of the lithosphere and its rheological profile, as well as the strength distribution. We find that the rheological stratification of the lithosphere in this region is apparent. The lowermost of the lower crust is ductile; however,the uppermost of the mantle and the upper and middle parts of the crust are both brittle layers,which is typically the so-called sandwich-like structure. Lithospheric strength is also characterized by the lateral variation, and the uplift region is stronger than the depression region. The lithospheric strength of the northem flank of the Tarim Basin decreases gradually from south to north; the Kuqa Depression has the lowest strength and the south of the Tabei Uplift is strongest.The total lithospheric strength of this region is 4.77× 1012-5.03 × 1013 N/m under extension, and 6.5 × 1012-9.4× 1013 N/m under compression. The lithospheric brittle-ductile transition depth is between 20 km and 33 km. In conclusion, the lithosphere of the northern flank of the Tarim Basin is relatively cold with higher strength, so it behaves rigidly and deforms as a whole, which is also supported by the seismic activity in this region. This rigidity of the

  6. From Back-arc Drifting to Arc Accretion: the Late Jurassic-Early Cretaceous Evolution of the Guerrero Terrane Recorded by a Major Provenance Change in Sandstones from the Sierra de los Cuarzos, Central Mexico

    Science.gov (United States)

    Palacios Garcia, N. B.; Martini, M.

    2014-12-01

    The Guerrero terrane composed of Middle Jurassic-Early Cretaceous arc assemblages, were drifted from the North American continental mainland during lower Early Cretaceous spreading in the Arperos back arc basin, and subsequently accreted back to the continental margin in the late Aptian. Although the accretion of the Guerrero terrane represents one of the major tectonic processes that shaped the southern North American Pacific margin, the stratigraphic record related to such a regional event was not yet recognized in central Mexico. Due to the Sierra de los Cuarzos is located just 50 km east of the Guerrero terrane suture belt, its stratigraphic record should be highly sensitive to first order tectonic changes and would record a syn-tectonic deposits related to this major event. In that study area, were identified two main Upper Jurassic-Lower Cretaceous clastic units. The Sierra de los Cuarzos formation represents the lowermost exposed stratigraphic record. Sedimentary structures, sandstones composition, and U-Pb detrital zircon ages document that the Sierra de los Cuarzos formation reflects a vigorous mass wasting along the margin of the North American continental mainland, representing the eastern side of the Arperos back arc basin. Sandstones of the Sierra de los Cuarzos formation are free from detrital contributions related to the Guerrero terrane juvenile sources, indicating that the Arperos Basin acted like an efficient sedimentological barrier that inhibited the influence of the arc massifs on the continental mainland deposits. The Sierra de los Cuarzos formation is overlain by submarine slope deposits of the Pelones formation, which mark a sudden change in the depositional conditions. Provenance analysis documents that sandstones from the Pelones formation were fed by the mafic to intermediate arc assemblages of the Guerrero terrane, as well as by quartz-rich sources of the continental mainland, suggesting that, by the time of deposition of the Pelones

  7. FACIES ANALYSIS, STRATIGRAPHY AND PALAEONTOLOGY (MOLLUSCS AND VERTEBRATES IN THE UPPER PLIOCENE SANDY FLOOD-BASIN DEPOSITS OF THE UPPER VALDARNO BASIN (NORTHERN APENNINES

    Directory of Open Access Journals (Sweden)

    MASSIMILIANO GHINASSI

    2005-11-01

    Full Text Available The Upper Valdarno Basin, one of the most investigated Neogene–Quaternary basins of the Northern Apennines, developed during three main phases, as testified by the occurrence of three unconformity-bounded stratigraphic units (UBSUs in the basin infill. Despite numerous studies having been carried out, biochronological, paleoecological and stratigraphical issues in the lower portion of the Montevarchi Synthem (second phase have yet to be understood. Sandy deposits (Montecarlo Sand and Silt Unit, stratigraphically located in this portion of the Montevarchi Synthem, are the focus of this multidisciplinary study. These deposits conformably overlie sandy fluvio-eolian sediments and are, in turn, capped by fluvio-palustrine deposits through a progressive unconformity. Facies analysis suggest a sandy flood-basin environment for these deposits, characterised by variations in water discharge and flood event energy. Mollusc and fish remains, pointing to quiet or slow-moving shallow waters, have been affected by transport processes before final burial in overbank areas. Fish remains of the primary marine family Mugilids highlight a connection between the basin and the sea that was previously only supposed. Small mammal remains, referred to the rodent Mimomys polonicus, are coherent with a water-rich environment. Cyclic variations in shell content and sedimentological characteristics testify to the occurrence of short-term climatic oscillations during this warming phase. This study fits with paleomagnetic and radiometric datings and mammal biochronology, in indicating that the Montecarlo Sand and Silt Unit belongs to a time interval preceding the Reunion paleomagnetic event. The depositional evolution of the Montecarlo Unit was driven by climatic change from arid to humid conditions, related to a global increase in temperature that occurred between 2.4 and 2.2 Ma.

  8. Cheatgrass percent cover change: Comparing recent estimates to climate change − Driven predictions in the Northern Great Basin

    Science.gov (United States)

    Boyte, Stephen P.; Wylie, Bruce K.; Major, Donald J.

    2016-01-01

    Cheatgrass (Bromus tectorum L.) is a highly invasive species in the Northern Great Basin that helps decrease fire return intervals. Fire fragments the shrub steppe and reduces its capacity to provide forage for livestock and wildlife and habitat critical to sagebrush obligates. Of particular interest is the greater sage grouse (Centrocercus urophasianus), an obligate whose populations have declined so severely due, in part, to increases in cheatgrass and fires that it was considered for inclusion as an endangered species. Remote sensing technologies and satellite archives help scientists monitor terrestrial vegetation globally, including cheatgrass in the Northern Great Basin. Along with geospatial analysis and advanced spatial modeling, these data and technologies can identify areas susceptible to increased cheatgrass cover and compare these with greater sage grouse priority areas for conservation (PAC). Future climate models forecast a warmer and wetter climate for the Northern Great Basin, which likely will force changing cheatgrass dynamics. Therefore, we examine potential climate-caused changes to cheatgrass. Our results indicate that future cheatgrass percent cover will remain stable over more than 80% of the study area when compared with recent estimates, and higher overall cheatgrass cover will occur with slightly more spatial variability. The land area projected to increase or decrease in cheatgrass cover equals 18% and 1%, respectively, making an increase in fire disturbances in greater sage grouse habitat likely. Relative susceptibility measures, created by integrating cheatgrass percent cover and temporal standard deviation datasets, show that potential increases in future cheatgrass cover match future projections. This discovery indicates that some greater sage grouse PACs for conservation could be at heightened risk of fire disturbance. Multiple factors will affect future cheatgrass cover including changes in precipitation timing and totals and

  9. Depositional Record of the Bagua Basin, Northern Peru: Implications for Climate and Tectonic Evolution of Tropical South America

    Science.gov (United States)

    Moreno, F.; George, S. W. M.; Williams, L. A.; Horton, B. K.; Garzione, C. N.

    2015-12-01

    The Andes Mountains exert critical controls on the climate, hydrology, and biodiversity of South America. The Bagua Basin, a low elevation (400-600 m) intermontane basin in northern Peru, offers a unique opportunity to study the ecological, climatic, and structural evolution of the western topographic boundary of the Amazonian foreland. Situated between the Marañon fold-thrust belt of the Western Cordillera and basement block uplifts of the Eastern Cordillera, the Bagua region contains a protracted, semi-continuous record of Triassic through Pleistocene sedimentation. Whereas Triassic-Cretaceous marine deposits were potentially related to extension and regional thermal subsidence, a Paleocene-Eocene shift to shallow marine and fluvial systems marks the onset of foreland basin conditions. Oligocene-Miocene sedimentation corresponds to a braided-meandering fluvial system with exceptional development of paleosols. In this study, we use new detrital zircon U-Pb geochronologic and oxygen stable isotopic datasets to establish a chronology of pre-Andean and Andean processes within the Bagua Basin. Detrital zircon geochronology provides constraints on when the Western and Eastern cordilleras shed sediments into the basin. Syndepositional zircons within Eocene, Oligocene and Miocene strata provide key age control for a previously poorly constrained depositional chronology. Preliminary results suggest a dramatic provenance shift in which Paleocene deposits contain almost exclusively cratonic populations (500-1600 Ma) whereas Eocene deposits show a mix of syndepositional zircons from the magmatic arc, recycled Mesozoic zircons, and cratonic zircon populations. Oxygen stable isotopes (δ18O) of carbonate nodules from Neogene paleosols will help elucidate when the Eastern Cordillera became an orographic barrier intercepting moisture from the Amazon basin to the east. Together, these records will help uncover the history of tectonics and climate interaction in tropical South

  10. Past, present and future formation of groundwater resources in northern part of Baltic Artesian Basin

    Science.gov (United States)

    Marandi, A.; Vallner, L.; Vaikmae, R.; Raidla, V.

    2012-04-01

    Cambrian-Vendian Aquifer System (CVAS) is the deepest confined aquifer system used for water consumption in northern part of Baltic Artesian Basin (BAB). A regional groundwater flow and transport model (Visual Modflow) was used to investigate the paleohydrogeological scientific and contemporary management problems of CVAS. The model covers the territory of Estonia and its close surrounding, all together 88,000 km2 and includes all main aquifers and aquitards from ground surface to as low as the impermeable part of the crystalline basement. Three-dimensional distribution of groundwater heads, flow directions, velocities, and rates as well as transport and budget characteristics were simulated by the model. Water composition was changed significantly during the last glaciations.Strongly depleted O and H stable isotope composition, absence of 3H and low radiocarbon concentration are the main indicators of glacial origin of groundwater in the Cambrian-Vendian aquifer in northern Estonia. The noble gas analyses allowed concluding, that palaeorecharge took place at temperatures around the freezing point. While in North Estonia, most of water was changed by glacial melt water, high salinity water is till preserved in Southern part of Estonia.First results of modeling suggest that during the intrusion period lasting 7.3-9.3 ka the front of glacial thaw water movement had southeast direction and reachedto 180-220 kmfrom CVAS outcrop in Baltic Sea. Confining layer of CVAS is cut through by deep buried valleys in several places in North Estonia making possible for modern precipitation to infiltrate into aquifer system in present day. In case of natural conditions, the water pressure of CVAS is few meters above sea level and most of valleys act as discharge areas for aquifers system. Two regional depression ones have formed in North Estonia as a result of groundwater use from CVAS. Water consumption changes the natural groundwater gradient, flow direction and thereforerecharge

  11. Review of the Upper Jurassic-Lower Cretaceous stratigraphy in Western Cameros basin, Northern Spain

    DEFF Research Database (Denmark)

    Vidal, Maria del Pilar Clemente

    2010-01-01

    The Upper Jurassic-Lower Cretaceous stratigraphy of the Cameros basin has been reviewed. In Western Cameros the stratigraphic sections are condensed but they have a parallel development with the basin depocentre and the same groups have been identified. The Tera Group consists of two formations: ...

  12. Structure of the Wagner Basin in the Northern Gulf of California From Interpretation of Seismic Reflexion Data

    Science.gov (United States)

    Gonzalez, M.; Aguilar, C.; Martin, A.

    2007-05-01

    The northern Gulf of California straddles the transition in the style of deformation along the Pacific-North America plate boundary, from distributed deformation in the Upper Delfin and Wagner basins to localized dextral shear along the Cerro Prieto transform fault. Processing and interpretation of industry seismic data adquired by Petroleos Mexicanos (PEMEX) allow us to map the main fault structures and depocenters in the Wagner basin and to unravel the way strain is transferred northward into the Cerro Prieto fault system. Seismic data records from 0.5 to 5 TWTT. Data stacking and time-migration were performed using semblance coefficient method. Subsidence in the Wagner basin is controlled by two large N-S trending sub-parallel faults that intersect the NNW-trending Cerro Prieto transform fault. The Wagner fault bounds the eastern margin of the basin for more than 75 km. This fault dips ~50° to the west (up to 2 seconds) with distinctive reflectors displaced more than 1 km across the fault zone. The strata define a fanning pattern towards the Wagner fault. Northward the Wagner fault intersects the Cerro Prieto fault at 130° on map view and one depocenter of the Wagner basin bends to the NW adjacent to the Cerro Prieto fault zone. The eastern boundary of the modern depocenter is the Consag fault, which extends over 100 km in a N-S direction with an average dip of ~50° (up to 2s) to the east. The northern segment of the Consag fault bends 25° and intersects the Cerro Prieto fault zone at an angle of 110° on map view. The acoustic basement was not imaged in the northwest, but the stratigraphic succession increases its thickness towards the depocenter of the Wagner basin. Another important structure is El Chinero fault, which runs parallel to the Consag fault along 60 km and possibly intersects the Cerro Prieto fault to the north beneath the delta of the Colorado River. El Chinero fault dips at low-angle (~30°) to the east and has a vertical offset of about 0

  13. Hydrological application of the INCA model with varying spatial resolution and nitrogen dynamics in a northern river basin

    Directory of Open Access Journals (Sweden)

    K. Rankinen

    2002-01-01

    Full Text Available As a first step in applying the Integrated Nitrogen model for CAtchments (INCA to the Simojoki river basin (3160 km2, this paper focuses on calibration of the hydrological part of the model and nitrogen (N dynamics in the river during the 1980s and 1990s. The model application utilised the GIS land-use and forest classification of Finland together with a recent forest inventory based on remote sensing. In the INCA model, the Hydrologically Effective Rainfall (HER is used to drive the water flow and N fluxes through the catchment system. HER was derived from the Watershed Simulation and Forecast System (WSFS. The basic component of the WSFS is a conceptual hydrological model which simulates runoff using precipitation, potential evapotranspiration and temperature data as inputs. Spatially uniform, lumped input data were calculated for the whole river basin and spatially semi-distributed input data were calculated for each of the nine sub-basins. When comparing discharges simulated by the INCA model with observed values, a better fit was obtained with the semi-distributed data than with the spatially uniform data (R2 0.78 v. 0.70 at Hosionkoski and 0.88 v. 0.78 at the river outlet. The timing of flow peaks was simulated rather well with both approaches, although the semi-distributed input data gave a more realistic simulation of low flow periods and the magnitude of spring flow peaks. The river basin has a relatively closed N cycle with low input and output fluxes of inorganic N. During 1982-2000, the average total N flux to the sea was 715 tonnes yr–1, of which 6% was NH4-N, 14% NO3-N, and 80% organic N. Annual variation in river flow and the concentrations of major N fractions in river water, and factors affecting this variation are discussed. Keywords: northern river basin, nitrogen, forest management, hydrology, dynamic modelling, semi-distributed modelling

  14. Geographic, geologic, and hydrologic summaries of intermontane basins of the northern Rocky Mountains, Montana

    Science.gov (United States)

    Kendy, Eloise; Tresch, R.E.

    1996-01-01

    This report combines a literature review with new information to provide summaries of the geography, geology, and hydrology of each of 32 intermontane basins in western Montana. The summary of each intermontane basin includes concise descriptions of topography, areal extent, altitude, climate, 1990 population, land and water use, geology, surface water, aquifer hydraulic characteristics, ground-water flow, and ground-water quality. If present, geothermal features are described. Average annual and monthly temperature and precipitation are reported from one National Weather Service station in each basin. Streamflow data, including the drainage area, period of record, and average, minimum, and maximum historical streamflow, are reported for all active and discontinued USGS streamflow-gaging stations in each basin. Monitoring-well data, including the well depth, aquifer, period of record, and minimum and maximum historical water levels, are reported for all long-term USGS monitoring wells in each basin. Brief descriptions of geologic, geophysical, and potentiometric- surface maps available for each basin also are included. The summary for each basin also includes a bibliography of hydrogeologic literature. When used alone or in conjunction with regional RASA reports, this report provides a practical starting point for site-specific hydrogeologic investigations.

  15. Seismicity patterns in the State of Guerrero, Mexico, 1974-2013: Its implication for the Guerrero Seismic Gap

    Science.gov (United States)

    Valdes-Gonzales, C. M.; Espindola, V.; Arreola-Manzano, J.

    2013-12-01

    The Guerrero Seismic Gap (GSG), has not been ruptured by a large earthquake (> 7.5), since 1911. The GSG is located along the Pacific Coast in central Guerrero State. This region, situated 300 km away from Mexico City, has been the site of important earthquakes, that have caused intensive damage at the capital of Mexico. A close look at the epicentral distribution in Guerrero State, between 1974 and 2013, shows that 3,496 earthquakes with magnitudes greater than 4, are located principally between the Middle America Trench and the coast, and a smaller number of events are located along a section that parallels the coast at about 80-110 Km inland. The hypocentral locations, mainly after 1995, when the digital seismic network started operating, show a good correlation with the generally proposed shallow dipping geometry of the subducting plate. Other observations in the epicentral distribution, are linear groups aligned with bathymetric features, and seismic clusters. Some of these regions can be seen as coalescence and fragmentation zones. There have been three slow-slip seismic events at the Guerrero region, every four years, between 1998 and 2010, and no particular epicentral distribution has been observed during these periods. Even with this large number of epicenters analyzed, is possible to distinguish the GSG. We analyze temporal variations of the epicentral and hypocentral distribution, and found that the seismic void for the GSG, suggest elliptical areas with width and length axis of 50-80 Km for the minimum area and 70-130 Km, for the maximum area. If this regions represent the possible rupture area of the expected earthquake, they will correspond to magnitudes of 7.6 to 8.2. The latest is the hypothetical working magnitude for the Mexican Federal Government. Although, with this information it is not possible to evaluate the state of the GSG, it is important to stablish the behavior of the seismicity before the ocurrance of an expected major earthquake.

  16. Hydrogeochemistry and stable isotopes of ground and surface waters from two adjacent closed basins, Atacama Desert, northern Chile

    Science.gov (United States)

    Alpers, C.N.; Whittemore, D.O.

    1990-01-01

    The geochemistry and stable isotopes of groundwaters, surface waters, and precipitation indicate different sources of some dissolved constituents, but a common source of recharge and other constituents in two adjacent closed basins in the Atacama Desert region of northern Chile (24??15???-24??45???S). Waters from artesian wells, trenches, and ephemeral streams in the Punta Negra Basin are characterized by concentrations of Na>Ca>Mg and Cl ???SO4, with TDS Mg ??? Ca and SO4 > Cl, with TDS also Mg ??? Ca and SO4 > Cl, but with TDS up to 40 g/l. The deep mine waters have pH between 3.2 and 3.9, and are high in dissolved CO2 (??13 C = -4.8%PDB), indicating probable interaction with oxidizing sulfides. The deep mine waters have ??18O values of ???-1.8%.compared with values isotopes at elevated temperatures. Alternatively, the deep mine waters may represent fossil meteoric waters which evolved isotopically along an evaporative trend starting from values quite depleted in ??18O and ??Dd relative to either precipitation or shallow groundwaters. High I/Br ratios in the Hamburgo Basin waters and La Escondida mine waters are consistent with regionally high I in surficial deposits in the Atacama Desert region and may represent dissolution of a wind-blown evaporite component. Rain and snow collected during June 1984, indicate systematic ??18O and ??D fractionation with increasing elevation between 3150 and 4180 m a.s.l. (-0.21??.??18O and -1.7??.??D per 100 m). Excluding the deep mine waters from La Escondida, the waters from the Hamburgo and Punta Negra Basins have similar ??D and ??18O values and together show a distinct evaporative trend (??D = 5.0 ??18O - 20.2). Snowmelt from the central Andes Cordillera to the east is the most likely source of recharge to both basins. Some of the waters in the Hamburgo Basin may have been recharged during late Pleistocene, when the climate was wetter and a lake filled the intervening Punta Negra Basin, as suggested by recent archaeological

  17. Seismo-stratigraphic evolution of the northern Austral Basin and its possible relation to the Andean tectonics, onshore Argentina.

    Science.gov (United States)

    Sachse, Victoria; Anka, Zahie; Pagan, Facundo; Kohler, Guillermina; Cagnolatti, Marcelo; di Primio, Rolando; Rodriguez, Jorge

    2013-04-01

    The Austral Basin is situated in a formerly and recently high active tectonic zone in southern Argentina. The opening of the South Atlantic to the east, the opening of the Drake Passage in the south, and the subduction related to the rise of the Andes to the west, had major influence on the study area. To identify the impact of the tectonic events on basin geometry, sediment thickness and depocenter migration through time, 2D seismic interpretation was performed for an area of approx. 180.000 km² covering the onshore northern Austral Basin. A total of 10 seismic horizons were mapped and tied to the stratigraphy from well reports, representing 9 syn- and post- rift sequences. The main units are: Basement (U1), Jurassic Tobifera Formation (U2), Early Cretaceous (U3), Late Cretaceous (U4), sub-unit Campanian (U4A), Paleocene (U5), Eocene (U6), Oligocene (U7), Miocene (U8), and Plio-Pleistocene (U9). Main tectonic events are identified representing the break-up phase forming graben systems and the evolution from the ancient backarc Rocas Verdes Basin to the foreland Austral Basin. Inversion and changes in the tectonic regime are concomitant with onlapping and thinning of the base of the Upper Cretaceous to Campanian sediments, while the Top of the Upper Cretaceous represents a Maastrichtian unconformity. Units depth maps show a triangular geometry since the Jurassic, tracing the north-eastern basement high and deepening to the south. Since the Campanian the former geometry of basin fill changed and deepening to the south stopped. Beginning of the foreland phase is assigned to this time as well as changes in the stress regime. Paleogene times are marked by a relatively high sedimentation rate coupled with enduring thermal subsidence, on-going rise of the Andes and changes in the convergence rates of the Nazca relative to the South American plate. Onset of sediment supply from the Andes (Incaic phase) resulted in enhanced sedimentation rates during the Paleocene

  18. Raft tectonics in northern Campos Basin; Tectonica de jangada (raft tectonics) na area norte da Bacia de Campos

    Energy Technology Data Exchange (ETDEWEB)

    Castro, Marilia R. de [Universidade Estadual do Norte Fluminense (UENF), Campos dos Goytacases, RJ (Brazil)]|[PETROBRAS, Macae, RJ (Brazil). Unidade de Negocio da Bacia de Campos; Fugita, Adhemar M. [Universidade do Estado, Rio de Janeiro, RJ (Brazil). Programa de Recursos Humanos da ANP

    2004-07-01

    In the northern area of Campos Basin salt gliding/spreading processes promoted the break-up and transport of Cretaceous and Tertiary rocks overlying the evaporites. This process is known as raft tectonics, and it represents the most extreme form of thin-skinned extension above the salt decollement surface. Three distinct geotectonic domains were recognized that formed in response to the raft tectonics. The first one, confined to the shallower shelf portion of the basin, is characterized by minor extension (pre-raft domain), probably because of small salt thickness and low gradient. In the second domain (or disorganized rafts domain), located in distal platformal and slope areas, seismic sections show the occurrence of blocks or rafts with angular shapes, sometimes imbricated and frequently discontinuous. In the third domain, or domain of organized rafts, located in bacinal region, seismic sections show a more continuous raft pattern, often folded because of salt compression in the distal portions of the basin. The main purposes of this work is to characterize these three tectonic domains distinguished by raft tectonics, as well as their importance in hydrocarbon accumulations in calcarenites. (author)

  19. Structural characteristics of an active fold-and-thrust system in the southeastern Atacama Basin, northern Chile

    Science.gov (United States)

    Lin, Yen-Sheng; Chuang, Yi-Rung; Shyu, J. Bruce H.; González, Gabriel; Shen, Chuan-Chou; Lo, Ching-Hua; Liou, Ya-Hsuan

    2016-08-01

    The western South American margin is one of the most active plate boundaries in the world. Using various remote sensing data sets, we mapped the neotectonic characteristics of an area at the southeastern corner of the Atacama Basin, northern Chile, in the Andean forearc. There, one major N-S trending ridge is clearly visible both in the satellite images and in the field. This ridge reaches 250 m above the basin floor in its middle part and is asymmetrical, with a steep eastern slope and a much gentler western slope. The geometry of the ridge indicates that it formed as an asymmetrical anticline. This anticline is likely formed as a shear fault-bend fold, with a major décollement at a depth of about 2.5 km in the Naranja Formation. We suggest that this décollement is a major structure of the Atacama Basin area. From the ages of the ignimbrites and lake deposits that were deformed by this anticline, we obtained a long-term shortening rate of the major underlying structure at about 0.2 mm/yr. This thin-skinned fold-and-thrust system appears to be active since at least about 3 Ma, and could be as long as since middle Miocene. Therefore, crustal structures may play important roles in the Neogene development of the western Andean margin.

  20. Analysis of subsurface temperature data to quantify groundwater recharge rates in a closed Altiplano basin, northern Chile

    Science.gov (United States)

    Kikuchi, C. P.; Ferré, T. P. A.

    2016-09-01

    Quantifying groundwater recharge is a fundamental part of groundwater resource assessment and management, and is requisite to determining the safe yield of an aquifer. Natural groundwater recharge in arid and semi-arid regions comprises several mechanisms: in-place, mountain-front, and mountain-block recharge. A field study was undertaken in a high-plain basin in the Altiplano region of northern Chile to quantify the magnitude of in-place and mountain-front recharge. Water fluxes corresponding to both recharge mechanisms were calculated using heat as a natural tracer. To quantify in-place recharge, time-series temperature data in cased boreholes were collected, and the annual fluctuation at multiple depths analyzed to infer the water flux through the unsaturated zone. To quantify mountain-front recharge, time-series temperature data were collected in perennial and ephemeral stream channels. Streambed thermographs were analyzed to determine the onset and duration of flow in ephemeral channels, and the vertical water fluxes into both perennial and ephemeral channels. The point flux estimates in streambeds and the unsaturated zone were upscaled to channel and basin-floor areas to provide comparative estimates of the range of volumetric recharge rates corresponding to each recharge mechanism. The results of this study show that mountain-front recharge is substantially more important than in-place recharge in this basin. The results further demonstrate the worth of time-series subsurface temperature data to characterize both in-place and mountain-front recharge processes.

  1. Geologic implications of large-scale trends in well-log response, northern Green River Basin, Wyoming

    International Nuclear Information System (INIS)

    Well-log response in lower Tertiary and Upper Cretaceous rocks in the northern Green River basin, Wyoming, is examined. Digitally recorded well-log data for selected wells located throughout the basin were processed by computer and displayed as highly compressed depth-scale plots for examining large-scale geologic trends. Stratigraphic units, formed under similar depositional conditions, are distinguishable by differing patterns on these plots. In particular, a strong lithologic contrast between Tertiary and underlying Upper Cretaceous non-marine clastic rocks is revealed and correlated through the study area. Laboratory analysis combined with gamma-ray spectrometry log data show that potassium feldspars in the arkosic Tertiary sandstones cause the contrast. The nature and extent of overpressuring has been examined. Data shift on shale conductivity and shale acoustic transit-time plots, previously ascribed to changes in pore pressure, correspond to stratigraphic changes and not necessarily with changes in pore pressure as indicated by drilling-mud weights. Gulf Coast well-log techniques for detecting overpressuring are unreliable and ineffectual in this basin, which has experienced significantly different geologic depositional and tectonic conditions

  2. Hydrogeology, groundwater levels, and generalized potentiometric-surface map of the Green River Basin lower Tertiary aquifer system, 2010–14, in the northern Green River structural basin

    Science.gov (United States)

    Bartos, Timothy T.; Hallberg, Laura L.; Miller, Cheryl E.

    2015-07-14

    In cooperation with the Bureau of Land Management, groundwater levels in wells located in the northern Green River Basin in Wyoming, an area of ongoing energy development, were measured by the U.S. Geological Survey from 2010 to 2014. The wells were completed in the uppermost aquifers of the Green River Basin lower Tertiary aquifer system, which is a complex regional aquifer system that provides water to most wells in the area. Except for near perennial streams, groundwater-level altitudes in most aquifers generally decreased with increasing depth, indicating a general downward potential for groundwater movement in the study area. Drilled depth of the wells was observed as a useful indicator of depth to groundwater such that deeper wells typically had a greater depth to groundwater. Comparison of a subset of wells included in this study that had historical groundwater levels that were measured during the 1960s and 1970s and again between 2012 and 2014 indicated that, overall, most of the wells showed a net decline in groundwater levels.

  3. The linkage between longitudinal sediment routing systems and basin types in the northern South China Sea in perspective of source-to-sink

    Science.gov (United States)

    Su, Ming; Hsiung, Kan-Hsi; Zhang, Cuimei; Xie, Xinong; Yu, Ho-Shing; Wang, Zhenfeng

    2015-11-01

    Using bathymetric and seismic data, this study describes the morpho-sedimentary features in Qiongdongnan basin and southwest Taiwan collision basin, northern South China Sea and reveals the linkages between sediment routing system and basin types. The modern Central Canyon in the Qiongdongnan basin is located along the rift margin, and subparallel to the shelf-break southeast of Hainan Island. The modern Central Canyon develops along the basin axis (i.e., Xisha Trough) and longitudinally transports sediments eastward which are mainly supplied by northern continental slope. The Penghu Canyon in the southwest Taiwan collision basin is located along the collision boundary parallel to the strike of the adjacent uplifted Taiwan orogen. The Penghu Canyon develops along the tilting basin axis transporting sediments longitudinally southward to the deep-sea basin and Manila Trench. The Penghu Canyon is supplied with sediments from both flank Kaoping and South China Sea slopes where tributary canyons and channels transport sediments down-slope and feed the axial canyon. The certain basin types may be occupied by particular styles of sediment routing system. By comparing the morpho-sedimentary features and basin characteristics associated with the modern Central Canyon to that of the Valencia Channel in NW Mediterranean Sea, the longitudinal sediment routing system in rift basin type can be determined. In contrast, the longitudinal sediment routing systems in collision setting can be represented by the comparable examples of Penghu Canyon in southwest Taiwan collision basin and Markham Canyon in western Solomon Sea. The rift type sediment routing system is characterized by an axial canyon with a single sediment supply from land drainage margin. In contrast, sediment routing system in collision type basins consists of an axial canyon and dual sediment supplies from flank adjacent slopes. The axial canyons in collision basins are more active than that of the rift basin due to

  4. Gravity and Magnetotelluric Modeling of the Santo Domingo Basin, Northern New Mexico

    Science.gov (United States)

    Zamudio, K. D.; Keithline, N.; Blum, C.; Cunningham, E.; Fromont, A.; Jorgensen, M.; Lee, R.; McBride, K.; Saez Berrios, P.; Harper, C.; Pellerin, L.; McPhee, D.; Ferguson, J. F.

    2015-12-01

    The Santo Domingo Basin, one of a series of basins within the Rio Grande Rift, is located between Santa Fe and Albuquerque, NM, and has been the focus of research by the Summer of Geophysical Experience (SAGE) program since 2000. Gravity, magnetotelluric (MT), and seismic data have been collected throughout the region, although we are concentrating on gravity and MT data collected during SAGE 2014 and 2015. The study area is located in the center of the Santo Domingo basin, an extensional, Miocene age, rift basin, in an area that was minimally involved in the preceding local Laramide orogenic activity. Rift sediments (~3.5 km thick) are underlain by Eocene age sediments that were shed from adjacent uplifts. Up to 3 km of Mesozoic and Paleozoic sediments are preserved above the Precambrian basement. Geologic outcrop, borehole and seismic reflection data, and known density values were used in the construction of a ~100 km-long, generalized geologic cross section from which a gravity response was calculated. The modeled gravity response makes fairly definitive predictions about the geometry of the basin as well as the stratigraphy and faulting within and bounding the basin. MT data was collected at ten stations within the basin. The MT sounding curves exhibit one-dimensional behavior at short periods (1000 ohm-m) at ~ 3.5-4 km. Conductivities of the major stratigraphic units have been determined from well logs and previous MT modeling. Forward and inverse MT models constrained by the gravity-modeled geologic cross section are used to develop a conductivity model consistent with the geology, and are a step towards a better unified treatment of MT, seismic and gravity data.

  5. Neotectonic aspects of the northern margin of the Adana–Cilicia submarine basin, NE Mediterranean

    Indian Academy of Sciences (India)

    E Ozel; A Ulug; B Pekcetinoz

    2007-04-01

    The sedimentary basins that dominate the north-eastern Mediterranean (Adana–Cilicia basins in the west and Iskenderun basin in the east) are located on the flanks of a partly submerged positive structure (a part of the Africa–Eurasia convergence zone) along which strike-slip faults are evident. This study summarizes the findings of two seismic surveys carried out in the Alanya– Mersin offshore region. Some 850 km of geophysical survey lines were compiled on these cruises. Based on the results determined from these surveys, the north and central part of Adana–Cilicia basin can be subdivided into eastern, central and western structural sub-basins separated by the Ecemiş fault complex in the east and the Anamur–Kormakiti structural high in the west at the same time. Results of this study also indicate that Ecemiş and Anamur–Kormakiti faults are active. Late Miocene regional compression was responsible for the compartmentation of this complex into the present arrangement and has initiated the rotational regime which has governed subsequent tectonic developments, notably the extensional behaviour of the NE–SW trending Ecemiş and Anamur–Kormakiti faults and the transpressive behaviour of the NNE–SSW trending border fault complex.

  6. Hydrochemistry (major and trace elements of Lake Malawi (Nyasa, Tanzanian Northern Basin: local versus global considerations

    Directory of Open Access Journals (Sweden)

    P. Branchu

    2010-07-01

    Full Text Available This paper presents the first inventory of dissolved minor and trace element (F, Al, Fe, Mn, Ba, Cd, Cr, Cu, Pb, Mo, Bi, Sr, Zn concentrations in Lake Malawi, the second largest African lake. Sampling was carried out during 1993 dry season in the northern part of the lake. Trace metal concentrations were measured, together with Ca, Mg, Na, K, Cl, SO4, Alkalinity and Si, along three profiles in the lake northern extremity, in five tributaries and two on-land hydrothermal springs. Water profiles show similar elemental distributions and concentrations that are influenced by lake physical-chemical stratification. Stratification, assessed using temperature, conductivity, Si and Mn profiles, is characterised by two boundaries: the thermocline (70–90 m and the oxicline (150–190 m. Elemental water concentrations are discussed using simple covariance analyse. Epilimnetic concentrations and distribution are also influenced by atmospheric deposition and river diving. Comparison of dissolved concentrations for potentially polluting elements with World Health Organisation Guidelines and those reported for other East African lakes shows that this reservoir is uncontaminated despite an increasing human stress. Major element behaviour is assessed through a 3 boxes model. In this model Cl and K are conservative elements whereas Si is removed from the solution by diatom productivity and sedimentation. Ca, Na, Mg and alkalinity show low reactivity. Evaporation is one of the controlling factors of lake element concentration that superimposes on the watershed control. Hydrothermal activity, not evidenced in the lake, controls the chemistry of one of the main northern tributary. Chemical comparison between Northern rivers and other tributaries characterises the geographical and geological specificity of studied northern watershed. Moreover the lake annual chemical budget shows that northern watershed generates the main elemental input to the lake

  7. Organic matter provenance, palaeoproductivity and bottom water anoxia during the Cenomanian/Turonian oceanic anoxic event in the Newfoundland Basin (northern proto North Atlantic Ocean)

    NARCIS (Netherlands)

    van Bentum, E.C.; Reichart, G.J.; Sinninghe Damsté, J.S.

    2012-01-01

    Free and sulfur-bound biomarkers in sediments deposited in the northern proto North Atlantic (Newfoundland Basin, ODP Site 1276) during the Cenomanian-Turonian oceanic anoxic event 2 (OAE-2) were studied. The delta C-13 records of phytane and lycopane confirmed the stratigraphic position of the posi

  8. Organic matter provenance, palaeoproductivity and bottom water anoxia during the Cenomanian/Turonian oceanic anoxic event in the Newfoundland Basin (northern proto North Atlantic Ocean)

    NARCIS (Netherlands)

    Bentum, E.C. van; Reichart, G.-J.; Sinninghe Damsté, J.S.

    2012-01-01

    Free and sulfur-bound biomarkers in sediments deposited in the northern proto North Atlantic (Newfoundland Basin, ODP Site 1276) during the Cenomanian-Turonian oceanic anoxic event 2 (OAE-2) were studied. The δ 13C records of phytane and lycopane confirmed the stratigraphic position of the positive

  9. National Account Energy Alliance Final Report for the Basin Electric Project at Northern Border Pipeline Company's Compressor Station #7, North Dakota

    Energy Technology Data Exchange (ETDEWEB)

    Sweetzer, Richard [Exergy Partners Corp.; Leslie, Neil [Gas Technology Institute

    2008-02-01

    A field research test and verification project was conducted at the recovered energy generation plant at Northern Border Pipeline Company Compressor Station #7 (CS#7) near St. Anthony. Recovered energy generation plant equipment was supplied and installed by ORMAT Technologies, Inc. Basin Electric is purchasing the electricity under a purchase power agreement with an ORMAT subsidiary, which owns and operates the plant.

  10. Recently active reverse faulting in the Atacama Basin area, northern Chile: Implications for the distribution of convergence across the western South America plate boundary

    Science.gov (United States)

    Shyu, J. H.; Gonzalez, G.; Simons, M.; Aron, F.; Veloso, A.

    2007-12-01

    The western South American margin is one of the most active continental plate boundaries in the world. The ongoing convergence between the Nazca plate, or formerly the Farallon plate, and the South American plate produced the wide deformation belt of the Andes. In order to obtain more information about the active deformations in the central Andean belt to better understand the current distribution of convergence across the orogen, we attempted to map major structures that appear to be active recently by their topographic expressions using SRTM DEM and Landsat satellite images, followed by field observations. Results of our mapping show that there are many reverse faults that may be recently active in the area surrounding the Atacama Basin, in the Preandean Depression in northern Chile. These include a series of active reverse faults and related folds at the southeastern corner of the Atacama Basin, a major fold system that may be produced by an underlying fault just east of the basin, and a series of folds that forms the Cordillera de la Sal in the northern and western part of the basin. At the southeastern corner of the Atacama Basin, several geomorphic features indicate that at least some of the structures there have been active quite recently, including small drainages that cut through the folds and form active alluvial fans. Similar features of active river incision across folds are also present in the northern part of the basin. The fold system east of the basin may be one of the most important structures in the area. Deformed lava flows and deflected drainages indicate that this structure has been active recently, and growth strata near the fold suggest that it has been active for several myr. If so, the structure may be a major reverse fault system that defines the eastern boundary of the Atacama Basin, and may thus be an important onland structure that is responsible for absorbing part of the plate convergence.

  11. Acciones ciudadanas en defensa del Centro Jos?? Guerrero

    OpenAIRE

    Guill??n Marcos, Esperanza

    2010-01-01

    Este texto resume las acciones emprendidas por una plataforma, de iniciativa civil, en defensa del mantenimiento en la ciudad de Granada del Centro Jos?? Guerrero, cuya permanencia est?? en peligro por la decisi??n unilateral de la Diputaci??n de Granada de crear una ???Fundaci??n granadina de Arte Contempor??neo???, luego aprobada con el nombre de FNEO, y de estructura meramente pol??tica, que pretend??a privar de su autonom??a al centro. Liquidado este importante espacio de debate art??stic...

  12. The northern and central Appalachian basin coal region -- The Upper Freeport and Pond Creek coal bed assessments

    Energy Technology Data Exchange (ETDEWEB)

    Ruppert, L.; Tewalt, S.; Bragg, L.; Wallack, R.; Freeman, P.; Tully, J.

    1999-07-01

    The Upper Freeport and Pond Creek coal beds are two of six coal beds being assessed by the US Geological Survey (USGS) in the northern and central Appalachian basin coal region. The coal resource assessments were designed to provide up-to-date, concise data on the location, quantity, and quality of US coals for Federal agencies, the public, industry and academia. Assessment products are fully digital and include original and remaining resource estimates; maps depicting areal extent, mined areas, geologic structure contour, isopach, overburden thickness, ash yield, sulfur content, calorific value, and selected trace-element contents; and public domain geochemical and stratigraphic databases. The assessment methodology and a few results are presented.

  13. Existing concepts of the formation of the Northern Czech lignite basin

    Energy Technology Data Exchange (ETDEWEB)

    Nurnik, S.

    1982-01-01

    In the Myocene period, the area of sediment accumulation occupied three times more area than the region of the basin's denudation. The Krushnyye Mountains and Czech Midland did not yet exist as orographic units. These morphostructures arose in the Pleistocene epoch. Both morphostructures are currently considered to be an integral part of the large fold.

  14. Cambrian Ichnofossils from the Zhoujieshan Formation (Quanji Group) Overlying Tillites in the Northern Margin of the Qaidam Basin, NW China

    Institute of Scientific and Technical Information of China (English)

    Yue Wang; Xunlian Wang; Ye Wang

    2015-01-01

    The Quanji Group is composed of siliciclastics and carbonates and was deposited on a relatively stable block, in the northern margin of the Qaidam Basin, NW China. It is one of the research hotspots in the Qilian-Qinling-Kunlun tectonic zones. However, it has long been argued whether the up-per Quanji Group should be assigned to the Precambrian or the Cambrian for lack of convincing fossil evidence. The discovery of ichnofossils, including Rusophycus, Cruziana, Dimorphichnus, Treptichnus, Skolithos, Arenicolites, Palaeophycus, and Helminthopsis, indicates that the upper member of the Zhou-jieshan Formation (top Quanji Group) is Cambrian in age, and at least above the Treptichnus (Phycodes) pedum Biozone, the lowermost biozone in the Cambrian. The lower member of the Zhoujieshan Forma-tion should belong to the Cambrian. During the time when the upper member of the Zhoujieshan For-mation was deposited, the northern margin of the Qaidam Basin was dominated by the Cruziana Ichno-facies, characterizing a lower-energy shelf (shallow) sea environment with moderate-rich oxygen con-tents. In addition, the conglomerates in the Hongtiegou Formation of the Quanji Group underlying the Zhoujieshan Formation were generally regarded as tillites. However, the dolostones of the lower member of the Zhoujieshan Formation are, in lithology and geochemistry, different from the typical cap-dolostones of the Doushantuo Formation in South China, so it is necessary to further study the ori-gins of the lower member of the Zhoujieshan Formation and the conglomerates of the Hongtiegou For-mation.

  15. Characteristics of high arsenic groundwater in Hetao Basin, Inner Mongolia, northern China

    Institute of Scientific and Technical Information of China (English)

    YangChun Zhu; XueYong Zhao; Min Chen; YongQing Luo; Xin Zhou

    2015-01-01

    It is well known that the Hetao Basin is one of the most seriously arsenic-affected groundwater areas in China. In order to understand the characteristics of high arsenic (As) groundwater in the Basin, a brief overview of arsenic in groundwater follows. High arsenic in the Basin commonly occurs in shallow groundwater and the total arsenic concentrations range from 0.58 to 572 µg/L (average 99.73 µg/L), exceeding the maximum mandated value of 10 µg/L for drinking water in China;As(Ш) is the predominant species. The regional distribution pattern of arsenic in the groundwater increases from south/southeast to north/northwest. Hangjinhouqi and Wuyuan counties are considered as the most seriously affected areas, with high incidences of endemic arsenicosic diseases in the Hetao Basin. High groundwater arsenic correlates with the increase of well depth. Previous studies proposed that groundwater arsenic in the Basin is mainly originated from desorption of some natural solid materials in the sediments, under reducing condition. Generally, reducing condition is believed to be the primary factor for arsenic releasing from the sediment to groundwater in the region. Under inorganic or bacterial processes, Fe2O3 changes to FeS and arsenic adsorbed to Fe(OH)3 dissolves into groundwater, and As(V) is re-duced to As(Ш). Besides, reducing environments, groundwater hydraulic gradients, organic matter, pH, evapotranspiration, and soil texture are presumed to be the predominant factors that control arsenic mobilization.

  16. Unroofing around Qaidam Basin of northern Tibet at 30 Ma:constraints from 40Ar/39Ar and FT thermochronology on granitoids

    Institute of Scientific and Technical Information of China (English)

    王非; 罗清华; 李齐; 万京林; 郑德文; 王二七

    2002-01-01

    An 40Ar/39Ar and fission track thermochronological study has been carried out on three suites of granitoids collected along the northern and southern edges of the Qaidam Basin to better constrain the mechanisms accommodating the India-Asia collision around the Qaidam Basin (northern Tibet), in order to understand the evolution of the entire deformation area. Mica and K-feldspar have been analyzed and the cooling histories of the latter have been modeled. The cooling histories based upon K-feldspar modeling and fission track ages show that samples simultaneously recorded an important cooling event (7.5-10.7℃/Ma) around 30 Ma, which is thought to reflect an increase of denudation rate related to the tectonic activity in this area associated with uplift suggesting significant crustal thickening starting around 30 Ma in this area. The estimated sedimentation rate in the Qaidam Basin, the propagation rate along the Altyn Tagh fault and field observations support this deduction.

  17. Bathymetric characterization of tectonically active basins in the northern Gulf of California

    Science.gov (United States)

    Prol-Ledesma, R. M.; Canet, C.; Dando, P. R.

    2009-04-01

    The Wagner Basin can be considered a "nascent spreading centre" that evolved from a half graben with a thick sediment cover that may mask magmatic activity at depth. The 200-210 m deep Wagner and Consag Basins are the northernmost of the 8 active extensional basins within the Gulf of California rift system and have been assumed to be mostly hydrothermally inactive; however, bathymetric data show dense deep faulting, mainly on the SE edge of the basins; additionally, the presence of extensive gas venting and heated sediments along the Wagner Fault was observed. Detailed bathymetry of the Wagner and Consag Basins shows the steep eastern edge of the basins bordered by the Wagner Fault. Bathymetry and profiler data revealed large vertical displacements due to faulting that disrupted the sedimentary column. More than 246 bubble plumes were mapped on the echo-sounder profiles, many rising to the surface from 65 -150 m depth and the area affected by low bottom pH, due to CO2 discharge, was in excess of 365 km2. Bubbles were observed breaking the sea surface from some large plumes. Only a minority of the vents present were mapped with the echo-sounders, since the closest survey lines were 1km apart. Based on the bottom coverage of the acoustic beam we estimate that there are at least 15,000 individual gas vents along the Wagner fault. Profiler images showed gas channels and chimneys associated with sedimentary layers. The gas plumes originated from sites of intense disruptions of the upper sediments (synsedimentary faults, pockmarks, mud domes and diapirs and raised irregular hard reflectors). Beneath the plumes, there were enhanced sedimentary reflectors and acoustic blanking indicative of subsurface gas accumulation. One of the strongest vents was associated with a mud diapir. Cemented sediments were common inside pockmarks and around gas outlets; 13 (22%) of grab and box core samples in the outgassing area contained these but in many cases the grab was empty after

  18. Seismic imaging and analysis of source and migration within an integrated hydrocarbon system study: Northern Gulf of Mexico Basin

    Energy Technology Data Exchange (ETDEWEB)

    Gross, Oliver P.; Hood, Kenneth C.; Harrison, Stanley C. [Exxon Exploration Co., Houston, TX (United States); Wenger, Lloyd M. [Exxon Production Research Co., Houston, TX (United States)

    1995-12-31

    The sources for hydrocarbons in young Tertiary reservoirs of the offshore Gulf of Mexico have been enigmatic in the past due to the lack of source rock penetration in offshore drilling. Exxon formed a multidisciplinary team to address source, maturation, and migration in the northern Gulf of Mexico. The study was initiated in a pilot area east of the Mississippi River Delta where the complete hydrocarbon system can be seismically imaged, then expanded to the west across much of the shelf and slope. Hydrocarbons from seeps and reservoirs were geochemically characterized across the entire northern Gulf of Mexico Basin, and direct oil to source rock correlations were made both offshore (in pilot area) and onshore. Modern 2-D and 3-D seismic was used to develop a geologic framework and to map potential offshore source intervals. The major sources identified offshore are centered on the Eocene, Turonian, Tithonian, and Oxfordian, and correspond to second-order sequence stratigraphic transgressions. (author). 1 fig., 1 tab

  19. Technique for the long-term projections of water balance components for northern river basins of Russia

    Science.gov (United States)

    Gusev, Yeugeniy; Nasonova, Olga

    2014-05-01

    The goal of the present work is a development of a technique for a long-term projection of changes in water resources of northern rivers of Russia caused by climate change. The technique is based on the land surface model SWAP and information on the land surface parameters taken from global data sets. SWAP is a physically-based model. A good accuracy of simulating different characteristics of the water and energy regimes under different conditions and on different spatial scales was confirmed by numerous validation of the model against measured data. As a result, it was concluded that SWAP can be a good tool for simulation of water balance components for various river basins both for the current climatic conditions and for the future ones. The northern river basins of Russia are covered with a sparse network of meteorological stations and poorly provided with land surface parameters. The latter was overcome by application of global data sets on land surface characteristics. Evidently, that direct application of such information leads to a low accuracy of model simulations. To improve the quality of river runoff modeling the main land surface parameters were calibrated using the SCE-UA algorithm and river runoff measurements. Optimization of model parameters has significantly improved the agreement between measured and simulated streamflow of northern rivers. The Nash-Satcliffe efficiency for the modeled daily streamflow varied from 0.70 to 0.85 and the absolute bias values reached 1-10 %. That allowed us to use the SWAP model for hydrological projections. In order to make sure that the land surface parameters, obtained for the modern period, remain valid in projection periods, the following investigation was carried out. For the Northern Dvina River, model transposability in time under contracted climate conditions was analyzed. In so doing, model calibration and validation was performed for contrasted climatic conditions in terms of temperature and precipitation

  20. Geochemical characteristics of pyrolysis gas from epimetamorphic rocks in the northern basement of Songliao Basin,Northeast China

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The Xushen gas field,located in the north of Songliao Basin,is a potential giant gas area for China in the future.Its proved reserves have exceeded 1000×10 8 m 3 by the end of 2005.But,the origin of natural gases from the deep strata is still in debating.Epimetamorphic rocks as a potential gas source are widely spreading in the northern basement of Songliao Basin.According to pyrolysis experiments for these rocks in the semi-confined system,gas production and geochemistry of alkane gases are discussed in this paper.The Carboniferous-Permian epimetamorphic rocks were heated from 300℃to 550℃,with temperature interval of 50℃.The gas production was quantified and measured for chemical and carbon isotopic compositions.Results show thatδ13C 1 is less than?20‰,carbon isotope trend of alkane gas isδ13C 1 <δ13C 2 <δ13C 3 orδ13C 1 <δ13C 2 >δ13C 3 ,these features suggest that the gas would be coal-type gas at high-over maturity,not be inorganic gas with reversal trend of gaseous alkanes (δ13C 1 >δ13C 2 >δ13C 3 ).These characteristics of carbon isotopes are similar with the natural gas from the basin basement,but disagree with gas from the Xingcheng reservoir.Thus,the mixing gases from the pyrolysis gas with coal-typed gases at high-over maturity or oil-typed gases do not cause the reversal trend of carbon isotopes.The gas generation intensity for epimetamorphic rocks is 3.0×10 8 ―23.8×10 8 m 3 /km 2 ,corresponding to Ro from 2.0%to 3.5%for organic matter.

  1. Assessment of River Habitat Quality in the Hai River Basin, Northern China

    OpenAIRE

    Yuekui Ding; Baoqing Shan; Yu Zhao

    2015-01-01

    We applied a river habitat quality (RHQ) assessment method to the Hai River Basin (HRB); an important economic centre in China; to obtain baseline information for water quality improvement; river rehabilitation; and watershed management. The results of the assessment showed that the river habitat in the HRB is seriously degraded. Specifically; 42.41% of the sites; accounting for a river length of 3.31 × 104 km; were designated poor and bad. Habitat in the plain areas is seriously deteriorated...

  2. Two new species of Pseudancistrus (Siluriformes, Loricariidae) from the Amazon basin, northern Brazil

    OpenAIRE

    Gabriel da Costa e Silva; Roxo, Fábio F; Claudio Oliveira

    2015-01-01

    Abstract Two new species of Pseudancistrus , a genus diagnosed by non-evertible cheek plates and hypertrophied odontodes along the snout margin, are described from two drainages of the Brazilian Shield: Pseudancistrus kayabi from the rio Teles Pires (rio Tapajós basin) and Pseudancistrus asurini from the rio Xingu. The new species are distinguished from congeners ( Pseudancistrus barbatus , Pseudancistrus corantijniensis , Pseudancistrus depressus , Pseudancistrus nigrescens , Pseudancistrus ...

  3. CLIMATE CHANGE IN NORTHERN AFRICA: TOWARDS A RETURN OF RAINFALL ON THE SOUTHERN MEDITERRANEAN BASIN

    OpenAIRE

    NOUACEUR ZEINEDDINE; Laignel, B.; TURKI IMEN; JEMAI HIBA

    2014-01-01

    To determine to what extent climate change affects the rainfall recorded on the southern Mediterranean basin, a trend analysis is proposed. This study is based on the chronological graphic method of processing information (MGCTI) of type "Matrice Bertin". Results show an extreme variability of the precipitations and a severe drought, especially for Morocco, observed since 1970s. Finally, a gradual return to humid conditions is observed from the beginning of the 2000s in Algeria and Tunisia an...

  4. Hydrogeochemical studies of historical mining areas in the Humboldt River basin and adjacent areas, northern Nevada

    Science.gov (United States)

    Nash, J. Thomas

    2005-01-01

    The study area comprises the Humboldt River Basin and adjacent areas, with emphasis on mining areas relatively close to the Humboldt River. The basin comprises about 16,840 mi2 or 10,800,000 acres. The mineral resources of the Humboldt Basin have been investigated by many scientists over the past 100 years, but only recently has our knowledge of regional geology and mine geology been applied to the understanding and evaluation of mining effects on water and environmental quality. The investigations reported here apply some of the techniques and perspectives developed in the Abandoned Mine Lands Initiative (AMLI) of the U.S. Geological Survey (USGS), a program of integrated geological-hydrological-biological-chemical studies underway in the Upper Animas River watershed in Colorado and the Boulder River watershed in, Montana. The goal of my studies of sites and districts is to determine the character of mining-related contamination that is actively or potentially a threat to water quality and to estimate the potential for natural attenuation of that contamination. These geology-based studies and recommendations differ in matters of emphasis and data collection from the biology-based assessments that are the cornerstone of environmental regulations.

  5. Oil geochemistry of the northern Llanos Basin, Colombia. A model for migration

    Energy Technology Data Exchange (ETDEWEB)

    Ramon, J.C. (Colorado School of Mines, Golden, CO (United States)); Dzou, L. (Baseline Resolution, Dallas, TX (United States))

    1996-01-01

    The chemical composition of 23 crude oils and one oil seep from Llanos Basin, Colombia were studied in detail by geochemical methods in order to understand their genetic relationship. A filling history model is proposed to explain the observed composition variations in Llanos Basin oils. Geochemical fingerprinting indicates that there are six families of crude oils. The biomarker compositions have been used to identify characteristics of the source rocks. The Llanos oils contain marine algal- derived [open quotes]C30 steranes[close quotes] (i.e., 24-n-propylcholestanes), which are diagnostic for oils generated from marine Cretaceous source rocks. A significant HC-contribution from a Tertiary source is also indicated by the presence of high concentration of the [open quotes]flowering plant[close quotes]-markers oleanane, bicadinanes and oleanoids. Low DBT/Phen, %sulfur values and high diasteranes concentration indicate that the source rock is clay-rich. Biomarker maturity parameters indicate a wide range of source-rock thermal maturities from early to late oil window. Heavy biodegradation has been particularly common among the first oils to fill reservoirs in central Llanos oil fields. The older altered heavy oils were mixed with a second pulse of oil explaining the wide range of oil gravities measured in the central Llanos Basin.

  6. Oil geochemistry of the northern Llanos Basin, Colombia. A model for migration

    Energy Technology Data Exchange (ETDEWEB)

    Ramon, J.C. [Colorado School of Mines, Golden, CO (United States); Dzou, L. [Baseline Resolution, Dallas, TX (United States)

    1996-12-31

    The chemical composition of 23 crude oils and one oil seep from Llanos Basin, Colombia were studied in detail by geochemical methods in order to understand their genetic relationship. A filling history model is proposed to explain the observed composition variations in Llanos Basin oils. Geochemical fingerprinting indicates that there are six families of crude oils. The biomarker compositions have been used to identify characteristics of the source rocks. The Llanos oils contain marine algal- derived {open_quotes}C30 steranes{close_quotes} (i.e., 24-n-propylcholestanes), which are diagnostic for oils generated from marine Cretaceous source rocks. A significant HC-contribution from a Tertiary source is also indicated by the presence of high concentration of the {open_quotes}flowering plant{close_quotes}-markers oleanane, bicadinanes and oleanoids. Low DBT/Phen, %sulfur values and high diasteranes concentration indicate that the source rock is clay-rich. Biomarker maturity parameters indicate a wide range of source-rock thermal maturities from early to late oil window. Heavy biodegradation has been particularly common among the first oils to fill reservoirs in central Llanos oil fields. The older altered heavy oils were mixed with a second pulse of oil explaining the wide range of oil gravities measured in the central Llanos Basin.

  7. Seismic velocity structure of the Guerrero gap, Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Dominguez, Jaime [Colegio de Ciencias y Humanidades, Plantel Sur, Universidad Nacional Autonoma de Mexico, Mexico, D.F. (Mexico); Suarez, Gerardo [Instituto de Geofisica, Universidad Nacional Autonoma de Mexico, Mexico, D.F. (Mexico); Comte, Diana [Departamento de Geofisica, Universidad de Chile, Santiago (Chile); Quintanar, Luis [Instituto de Geofisica, Universidad Nacional Autonoma de Mexico, Mexico, D.F. (Mexico)

    2006-04-15

    A two-dimensional velocity structure of the Guerrero gap was obtained by applying a damped least square method to hypocenters of local seismicity recorded by a telemetric network situated on the Guerrero coast, above Cocos plate subduction zone. The region was parameterized by a mesh of 64 cubes in six layers, a total of 384 blocks. The results of 3-D inversion showed that differences of P-wave velocity values among blocks along the strike of the subduction zone were {approx}0.25 km/s, effectively showing a two-dimensional symmetry. A 2-D inversion taking into account velocity similarities among the 2-D bands generated megablocks. A final inversion procedure yields P-wave velocity values ranging from 5.4 to 8.2 km/s, and S-wave values from 3.2 and 4.7 km/s, suggesting a continental crust with a thickness of {approx}32 km composed of four flat megablocks with a P-wave velocity interval of 5.4 to 7.1 km/s. The Moho interface lies at {approx}32 km depth and above a mantle wedge between continental and oceanic crust. The downgoing oceanic crust has three layers (7.2-7.7 km/s), dipping at an angle of {approx}26 degrees. A sharp velocity change at a depth of {approx}30 km suggests a phase change from basalt to eclogite (7.2 to 7.6 km/s). The mantle has an average velocity of 8.2 km/s. The new velocity model reduced the error in locations and fits better the characteristics of the Guerrero gap. [Spanish] Se obtiene la estructura bidimensional de velocidades sismicas de la brecha de Guerrero aplicando el metodo de minimos cuadrados amortiguados a los datos de la sismicidad local registrada por una red telemetrica situada en la costa, ubicada en la zona de subduccion de la placa de Cocos. La region se parametrizo con una malla de 64 cubos en seis capas, un total de 384 bloques. Los resultados de esta inversion tridimensional (3-D) mostraron una diferencia de velocidad de onda P, entre bloques adyacentes y paralelos a la costa, no mayor de 0.25 km/s, mostrando una simetria

  8. Two new species of Pseudancistrus (Siluriformes, Loricariidae) from the Amazon basin, northern Brazil.

    Science.gov (United States)

    Silva, Gabriel S C; Roxo, Fábio F; Oliveira, Claudio

    2015-01-01

    Two new species of Pseudancistrus, a genus diagnosed by non-evertible cheek plates and hypertrophied odontodes along the snout margin, are described from two drainages of the Brazilian Shield: Pseudancistruskayabi from the rio Teles Pires (rio Tapajós basin) and Pseudancistrusasurini from the rio Xingu. The new species are distinguished from congeners (Pseudancistrusbarbatus, Pseudancistruscorantijniensis, Pseudancistrusdepressus, Pseudancistrusnigrescens, Pseudancistrusreus, and Pseudancistruszawadzkii) by the coloration pattern. Pseudancistruskayabi has dark bars on the dorsal and caudal fins which are similar to that of Pseudancistrusreus from the Caroní River, Venezuela. Pseudancistrusasurini is unique among Pseudancistrus in having whitish tips of the dorsal and caudal fins in juveniles to medium-sized adults.

  9. Study of Ground-Water Recharge Rates in the Northern Powder River Basin

    Science.gov (United States)

    Healy, R. W.; Bartos, T. T.

    2003-12-01

    Coal-bed methane (CBM) production in the Powder River Basin is growing rapidly. The Bureau of Land Management estimates that by the year 2010 there may be as many as 50,000 producing wells in the Wyoming part of the Basin alone. Development of CBM requires the pumping of water from coal seams. As water pressure in the seam is lowered, methane is released from storage. The pumped water is usually discharged into streams, channels, or impoundments. With a typical well producing about 48 cubic meters of water per day, the rate of discharge for the Basin could exceed 2.4 million cubic meters per day by 2010. The fate of that water and its impact on the environment are topics of some concern. Relevant issues include the rate at which water infiltrates and percolates to the water table, the eventual discharge of infiltrated water to surface water, and chemical changes that occur as water moves through the system. An adequate understanding of these issues requires knowledge of local and regional hydrology. This study is investigating rates of ground-water recharge under natural conditions and as impacted be CBM development. Natural recharge within the Powder River Basin occurs by both diffuse mechanisms (infiltration of precipitation and subsequent travel of water through the unsaturated zone to the water table) and focused mechanisms (infiltration from line and point sources, such as streams and ponds). Under natural conditions, the relative importance of each is difficult to assess. Discharged CBM water should substantially enhance the rate of focused recharge, with less effect expected on diffuse recharge. Objectives of this study are to estimate rates of diffuse recharge, naturally occurring focused recharge, and enhanced focused recharge due to the discharge of CBM water. Multiple approaches are being employed: chloride mass balance; tracer methods based on tritium, stable isotopes, and other compounds; Darcy/unit hydraulic gradient; water budget; water

  10. CLIMATE CHANGE IN NORTHERN AFRICA: TOWARDS A RETURN OF RAINFALL ON THE SOUTHERN MEDITERRANEAN BASIN

    Directory of Open Access Journals (Sweden)

    NOUACEUR ZEINEDDINE

    2014-03-01

    Full Text Available To determine to what extent climate change affects the rainfall recorded on the southern Mediterranean basin, a trend analysis is proposed. This study is based on the chronological graphic method of processing information (MGCTI of type "Matrice Bertin". Results show an extreme variability of the precipitations and a severe drought, especially for Morocco, observed since 1970s. Finally, a gradual return to humid conditions is observed from the beginning of the 2000s in Algeria and Tunisia and since 2008 in Morocco. This new trend is also confirmed by recent results provided by agricultural data of 2011/2012 and 2012/2013.

  11. Snow cover dynamics and hydrological regime of the Hunza River basin, Karakoram Range, Northern Pakistan

    Directory of Open Access Journals (Sweden)

    A. A. Tahir

    2011-03-01

    Full Text Available A major proportion of flow in the Indus River is contributed by its snow- and glacier-fed river catchments situated in the Himalaya, Karakoram and Hindukush ranges. It is therefore essential to understand the cryosphere dynamics in this area for water resource management. The MODIS MOD10A2 remote-sensing database of snow cover products from March 2000 to December 2009 was selected to analyse the snow cover changes in the Hunza River basin (the snow- and glacier-fed sub-catchment of the Indus River. A database of daily flows for the Hunza River at Dainyor Bridge over a period of 40 years and climate data (precipitation and temperature for 10 years from three meteorological stations within the catchment was made available to investigate the hydrological regime in the area. Analysis of remotely sensed cryosphere (snow and ice cover data showed a slight expansion of snow cover in the area in contrast to most of the regions in the world where glaciers are melting rapidly. This increase in snow cover may be the result of an increase in winter precipitation caused by westerly circulation. The impact of global warming is not effective because a large part of the basin area lies under high altitudes where the temperature remains negative throughout most of the year.

  12. Snow cover dynamics and hydrological regime of the Hunza River basin, Karakoram Range, Northern Pakistan

    Science.gov (United States)

    Tahir, A. A.; Chevallier, P.; Arnaud, Y.; Ahmad, B.

    2011-07-01

    A major proportion of flow in the Indus River is contributed by its snow- and glacier-fed river catchments situated in the Himalaya, Karakoram and Hindukush ranges. It is therefore essential to understand the cryosphere dynamics in this area for water resource management. The MODIS MOD10A2 remote-sensing database of snow cover products from March 2000 to December 2009 was selected to analyse the snow cover changes in the Hunza River basin (the snow- and glacier-fed sub-catchment of the Indus River). A database of daily flows for the Hunza River at Dainyor Bridge over a period of 40 yr and climate data (precipitation and temperature) for 10 yr from three meteorological stations within the catchment was made available to investigate the hydrological regime in the area. Analysis of remotely sensed cryosphere (snow and ice cover) data during the last decade (2000-2009) suggest a rather slight expansion of cryosphere in the area in contrast to most of the regions in the world where glaciers are melting rapidly. This increase in snow cover may be the result of an increase in winter precipitation caused by westerly circulation. The impact of global warming is not effective because a large part of the basin area lies under high altitudes where the temperature remains negative throughout most of the year.

  13. Snow cover dynamics and hydrological regime of the Hunza River basin, Karakoram Range, Northern Pakistan

    Directory of Open Access Journals (Sweden)

    A. A. Tahir

    2011-07-01

    Full Text Available A major proportion of flow in the Indus River is contributed by its snow- and glacier-fed river catchments situated in the Himalaya, Karakoram and Hindukush ranges. It is therefore essential to understand the cryosphere dynamics in this area for water resource management. The MODIS MOD10A2 remote-sensing database of snow cover products from March 2000 to December 2009 was selected to analyse the snow cover changes in the Hunza River basin (the snow- and glacier-fed sub-catchment of the Indus River. A database of daily flows for the Hunza River at Dainyor Bridge over a period of 40 yr and climate data (precipitation and temperature for 10 yr from three meteorological stations within the catchment was made available to investigate the hydrological regime in the area. Analysis of remotely sensed cryosphere (snow and ice cover data during the last decade (2000–2009 suggest a rather slight expansion of cryosphere in the area in contrast to most of the regions in the world where glaciers are melting rapidly. This increase in snow cover may be the result of an increase in winter precipitation caused by westerly circulation. The impact of global warming is not effective because a large part of the basin area lies under high altitudes where the temperature remains negative throughout most of the year.

  14. Hydrogeochemistry of high iodine groundwater: a case study at the Datong Basin, northern China.

    Science.gov (United States)

    Li, Junxia; Wang, Yanxin; Xie, Xianjun; Zhang, Liping; Guo, Wei

    2013-04-01

    High iodine concentrations in groundwater have seldom been reported and there have been few systematic studies on high iodine groundwater worldwide. To better understand the sources and processes responsible for iodine enrichment in the groundwater of the Datong Basin, the hydrochemical characteristics of groundwater and geochemical features of aquifer sediments were studied. High iodine groundwater mainly occurs in the center of the Datong Basin with iodine concentrations ranging between 3.31 and 1890 μg L(-1). Most samples with iodine concentrations higher than 500 μg L(-1) are from wells with depths between 75 and 120 m. High pH and a reducing environment are favorable for iodine enrichment in the groundwater, with iodide as the dominant species that accounts for 63.2-99.3% of the total iodine. Sediment samples from a borehole specifically drilled for this study contain 0.18-1.46 mg kg(-1) iodine that is moderately correlated with total organic carbon (TOC). The results of sequential extraction experiments show that iodine is mostly bound to iron oxyhydroxides and organic matter in the sediments. The mobilization processes of iodine are proposed to include reductive dissolution of iron oxyhydroxides and transformations among iodide, iodate and organic iodine driven by microbial activities under alkaline and reducing conditions. PMID:23478640

  15. Water-quality assessment of the Central Arizona Basins, Arizona and northern Mexico; environmental setting and overview of water quality

    Science.gov (United States)

    Cordy, Gail E.; Rees, Julie A.; Edmonds, Robert J.; Gebler, Joseph B.; Wirt, Laurie; Gellenbeck, Dorinda J.; Anning, David W.

    1998-01-01

    The Central Arizona Basins study area in central and southern Arizona and northern Mexico is one of 60 study units that are part of the U.S. Geological Survey's National Water-Quality Assessment program. The purpose of this report is to describe the physical, chemical, and environmental characteristics that may affect water quality in the Central Arizona Basins study area and present an overview of water quality. Covering 34,700 square miles, the study area is characterized by generally north to northwestward-trending mountain ranges separated by broad, gently sloping alluvial valleys. Most of the perennial rivers and streams are in the northern part of the study area. Rivers and streams in the south are predominantly intermittent or ephemeral and flow in response to precipitation such as summer thunderstorms. Effluent-dependent streams do provide perennial flow in some reaches. The major aquifers in the study area are in the basin-fill deposits that may be as much as 12,000 feet thick. The 1990 population in the study area was about 3.45 million, and about 61 percent of the total was in Maricopa County (Phoenix and surrounding cities). Extensive population growth over the past decade has resulted in a twofold increase in urban land areas and increased municipal water use; however, agriculture remains the major water use. Seventy-three percent of all water with drawn in the study area during 1990 was used for agricultural purposes. The largest rivers in the study area-the Gila, Salt, and Verde-are perennial near their headwaters but become intermittent downstream because of impoundments and artificial diversions. As a result, the Central Arizona Basins study area is unique compared to less arid basins because the mean surface-water outflow is only 528 cubic feet per second from a total drainage area of 49,650 square miles. Peak flows in the northern part of the study area are the result of snowmelt runoff; whereas, summer thunderstorms account for the peak flows in

  16. Tectonics and paleogeography of the Marajó Basin, northern Brazil

    Directory of Open Access Journals (Sweden)

    JOÃO B. S. COSTA

    2002-09-01

    Full Text Available The Marajó Basin area presents geologic and geomorphologic features chiefly due to the Mesozoic extension and post-Miocene neotectonics. The extension event with an Early and a Late Cretaceous phases originated four sub-basins that constitutes the Marajó Basin, with a thick continental clastic sequence showing marine influence. NW and NNW normal faults and NE and ENE strike-slip faults controlled the basin geometry. The extension, related to the Equatorial Atlantic opening, propagated into the continent along crustal weakness zones of the Precambrian Tumucumaque, Amapá and Araguaia orogenic belts. The neotectonic event is a strike-slip regime which developed transtensional basins filled in by Upper Tertiary shallow marine (Pirabas Formation and transitional sequences (Barreiras Group, followed by Quaternary fluvial deposits and transitional sequences derived from the Amazon and Tocantins rivers and the Marajoara estuary. The current landscape has a typical estuarine morphology. The coast morphology presents sea-cliffs on transitional Upper Tertiary sequences, while inwards dominate hills sustained by Mid-Pleistocene lateritic crust, with a flat erosive surface at 70 m. In the eastern Marajó Island several generations of paleochannels associated with fluvial-estuarine sequences are recognized, while a fluvial-marine plain is widespread on its western side.A área da Bacia do Marajó apresenta feições geológicas e geomorfológicas devidas principamente à distensão Mesozóica e à neotectônica pós-miocênica. O evento de distensão, com fases do Cretáceo Inferior e Superior, originou quatro sub-bacias que contituem a Bacia do Marajó, com uma espessa seqüência clástica continental mostrando influência marinha. Falhas normais NW e NNW e direcionais NE e ENE controlaram a geometria da bacia. A distensão, relacionada com a abertura do Atlântico Equatorial, propagou-se continente adentro ao longo de zonas de fraqueza crustal dos

  17. Evolutionary relationship between marble trout of the northern and the southern Adriatic basin.

    Science.gov (United States)

    Pustovrh, G; Sušnik Bajec, S; Snoj, A

    2011-06-01

    Marble trout (Salmo marmoratus) populate two geographically separated areas in the northern and southern parts of the Adriatic Sea drainage. Although morphologically similar, each population is distinguished by a different set of unrelated mitochondrial haplotypes, suggesting that they have evolved from different ancestors. Due to a possible discordance between mitochondrial and species phylogeny, we performed phylogenetic analysis based on 22 nuclear loci. The results inferred from Maximum-likelihood and Bayesian Inference analysis revealed that northern and southern populations are closely related, forming a monophyletic group. This observation is concordant with the present marble trout classification, which considers both populations as conspecific. On the other hand, our findings are in marked contrast to those of previous mtDNA-based studies and highlight potential dangers of making phylogenetic inferences from mtDNA alone. Reasons for discordance between mtDNA and nDNA phylogeny are discussed with incomplete lineage sorting proposed as the most parsimonious explanation for mtDNA divergence in marble trout.

  18. INNOVATIVE METHODOLOGY FOR DETECTION OF FRACTURE-CONTROLLED SWEET SPOTS IN THE NORTHERN APPALACHIAN BASIN

    Energy Technology Data Exchange (ETDEWEB)

    Robert Jacobi; John Fountain

    2001-02-28

    In the structure task, we completed a N-S transect east of Seneca Lake that indicated a N-striking fault near the southeastern shore of Seneca Lake, and also indicated NE and ENE-trending FIDs and faults north of Valois. The orientation and existence of the NE-striking FIDs and faults are thought to be controlled by basement faults, rather than thrust ramps above the Salina salt controlled only by a far-field Alleghanian stress field. Structure contour maps based on well log analyses have been constructed but not interpreted. Soil gas data displayed a number of ethane-charged soil gas ''spikes'' on a N-S transect from Ovid south to near Valois. The soil gas team found a larger number of spikes in the northern half of the survey, suggesting more open fractures (and faults) in the northern half of the survey. Seismic data has been purchased and reprocessed. Several grabens observed in the Trenton reflector are consistent with surface structure, soil gas, and aeromagnetic anomalies. The aeromagnetic survey is completed and the data is processed. Prominent magnetic anomalies suggest that faults in the Precambrian basement are located beneath regions where grabens in the Trenton are located.

  19. U-Pb Geochronology, Geochemistry and Kinematic Analyses of Subduction-Related Late Triassic Basins in Northern Chile (24.5º-26ºS).

    Science.gov (United States)

    Espinoza, M. E.

    2015-12-01

    In northern Chile (24.5°-26°S) two Pre-Andean depocenters crop out: the Cifuncho basin in the Coastal Cordillera and the Profeta basin in the Precordillera. These basins have been classically interpreted as a continental rifting unrelated to subduction during the period prior to the Andean orogenic cycle. However, recent petrographic and geochemical data suggest the development of these basins in an active subduction system. In order to test this hypothesis and to establish the geologic evolution of the basins and the strain field during the rifting process, we present preliminary U-Pb geochronological and geochemical data together with structural analyses of synrift structures. The geochronological data along the Cifuncho and Profeta basins, show a main continental sedimentary deposition during the Norian to Raethian. Volcanosedimentary rocks show a main detrital supply of Early Permian age (~297-283 Ma). This input can be associated with the volcanic La Tabla Formation and/or the exhumation of Permian granitoids. A minor supply close to ~478 Ma is related to a source from the Lower Ordovician arc (~480 Ma), suggesting the tectonic exhumation of this source to the east of the Profeta basin during the Late Triassic. On the other hand, structural analysis was carried in third and four order extensional faults (<10 m of slip) along the Profeta basin. Most of the faults show a clear synrift character with the development of fault controlled growing strata. The kinematic analyses evidence a variability in the orientation of the maximum strain axes from a main northwest to a subordinate northeast direction of extension. Thus, the intimate relation between the continental sedimentary deposition and a proximal volcanism of intermediate composition and calk-alkaline affinity, suggests the development of these basins in a supra-subduction setting during the Late Triassic. Structural data probably reflect local variation in the strain field across the basins.

  20. Shelf-edge sedimentary systems off Rio de Janeiro State, northern Santos basin-Brazil

    Science.gov (United States)

    Maia, R. M. C.; Dos Reis, A. T.; Gorini, C.; Silva, C. G.; Rabineau, M.; Granjeon, D.

    2012-04-01

    elements provide a hint at a prevailing subsidence regime and effective sediment supply into the basin that clearly contrast with the conveyed idea of a sediment-starved and tectonic stable shelf. They naturally raise questions about the nature and origin of sediment supply, since no significant point siliciclastic fluvial source flows directly into the shelf. Stemming from that, we are forced to speculate about: (A) the role of neotectonic movements involving the Serra do Mar coastal mountain ranges to potentially source clastic influx into the basin during the Quaternary, or about the real importance of secondary drainage basins debouching today; and (B) the mechanical nature of a supposed subsidence during the Pliocene and the Quaternary time span (overloading ? sediment compaction ? thermal cooling ?). The interpretation of industrial seismic lines can provide the answers of many of these questions. The next step of this work is to make a stratigraphy model of the sedimentary systems of Santos basin to understand how the ancient creation of accommodation space can influence the recent sedimentary architecture and how is the change in sedimentary influx and the sedimentary records of different orders of cyclicity.

  1. Two new species of Pseudancistrus (Siluriformes, Loricariidae from the Amazon basin, northern Brazil

    Directory of Open Access Journals (Sweden)

    Gabriel da Costa e Silva

    2015-02-01

    Full Text Available Two new species of Pseudancistrus, a genus diagnosed by non-evertible cheek plates and hypertrophied odontodes along the snout margin, are described from two drainages of the Brazilian Shield: P. kayabi from the rio Teles Pires (rio Tapajós basin and P. asurini from the rio Xingu. The new species are distinguished from congeners (P. barbatus, P. corantijniensis, P. depressus, P. nigrescens, P. reus, and P. zawadzkii by the coloration pattern. Pseudancistrus kayabi has dark bars on the dorsal and caudal fins which are similar to that of P. reus from the Caroní River, Venezuela. Pseudancistrus asurini is unique among Pseudancistrus in having whitish tips of the dorsal and caudal fins in juveniles to medium-sized adults.

  2. Clay mineralogical and geochemical constraints on late Pleistocene weathering processes of the Qaidam Basin, northern Tibetan Plateau

    Science.gov (United States)

    Miao, WeiLiang; Fan, QiShun; Wei, HaiCheng; Zhang, XiYing; Ma, HaiZhou

    2016-09-01

    At the Qarhan Salt Lake (QSL) on the central-eastern Qaidam Basin, northern Tibetan Plateau, Quaternary lacustrine sediments have a thickness of over 3000 m and mainly composed of organic-rich clay and silty clay with some silt halite and halite. In this study, a 102-m-long sediment core (ISL1A) was obtained from the QSL. Combining with AMS 14C and 230Th dating, clay minerals and major-element concentrations of ISL1A were used to reconstruct the weathering process and trend of the QSL since late Pleistocene. The results reveal that the clay mineral from rocks, gneisses and schists of Eastern Kunlun Mountains on the south of the QSL. The abundance of illite mineral displays an opposite fluctuation trending with that of smectite, chlorite and kaolinite mineral in ISL1A, which is significantly different from the monsoon-controlled regions. Moreover, higher values of illite, kaolinite/chlorite and illite/chlorite ratios, and lower values of smectite, chlorite and kaolinite minerals occurred in 83-72.5 ka, 68.8-54 ka, 32-24 ka, corresponding to late MIS 5, late MIS 4, early MIS 3 and late MIS 3, respectively. These three phases were almost similarly changed with oxygen isotopes of authigenic carbonates and pollen records in ISL1A, which implies that stronger chemical weathering corresponds to higher effective moisture periods of source region in the Qaidam Basin. Based on chemical weathering index and (Al2O3-(CaO + Na2O)-K2O) diagram, chemical weathering degree in this study area takes a varying process from low to intermediate on the whole.

  3. Late Quaternary tectonics in the inner Northern Apennines (Siena Basin, southern Tuscany, Italy) and their seismotectonic implication

    Science.gov (United States)

    Brogi, Andrea; Capezzuoli, Enrico; Martini, Ivan; Picozzi, Matteo; Sandrelli, Fabio

    2014-05-01

    Defining the most recent Quaternary tectonics represents a challenging task for neotectonic, palaeoseismological and seismotectonic studies. This paper focuses on an integrated approach to reconstructing the latest Quaternary deformation affecting the northern part of the Siena Basin (inner Northern Apennines, i.e., southern Tuscany, Italy) near the town of Siena, and to discuss the seismological implications. Field work and structural and stratigraphic analyses, coupled with the interpretation of reflection seismic lines, have been combined to define the geometry, kinematics and age of mesoscopic to map-scale faults which have affected the mainly Quaternary continental and Pliocene marine deposits. The resulting dataset describes a tectonic setting characterized by coeval SW- and NW-trending transtensional and normal faults, respectively, dissecting alluvial sediments younger than 23.9 ± 0.23 ka. Seismic interpretation sheds light on the geometrical setting of the faults at deeper levels, down to 1-2 km, and provides support for the presence of a wide brittle shear zone defined by conjugated fault segments, locally giving rise to an asymmetrical negative flower-like structure. Faults and their damage zones have controlled (and still control) the discharge of gas vents (mainly CO2 and H2S) and hydrothermal circulation (which deposits travertine) since at least 23.216 ± 0.124 ka. The resulting complete data set provides support for our description of the Neogene-Quaternary tectonics which were active until the late Quaternary, providing additional information about the seismotectonic framework of an area characterized by low seismicity and generally low-magnitude earthquakes (M < 4), but having experienced significant seismic events over the last few centuries.

  4. ATTENUATION OF SEISMIC WAVES IN THE LITHOSPHERE OF THE NORTHERN PART OF THE BASIN AND RANGE PROVINCE

    Directory of Open Access Journals (Sweden)

    А. А. Dobrynina

    2015-09-01

    Full Text Available This paper presents results of the study of attenuation of seismic waves in the lithosphere and upper mantle of the northern part of the Basin and Range Province (BRP (Fig. 1. In this study, the coda-wave method [Aki, Chouet, 1975] is applied to process data collected in the seismic experiment conducted in 1988–1989, PASSCAL Basin and Range Passive Seismic Experiment [Owens, Randall, 1989], including records of 66 earthquakes and explosions (Mb=1.1–5.0 which occurred in BRP (Fig. 2.The effective seismic quality factor by the coda is calculated using the single-backscattering model [Aki, Chouet, 1975]. The QC values are calculated for 18 values of the lapse time window W from 10 to 95 sec with the step of 5 sec at six (6 central frequencies (0.3, 0.75, 1.5, 3.0, 6.0, and 12.0 Hz. In total, 7776 individual measurements of QC were done. It is observed that the quality factor QC is strongly dependent on the frequency and the lapse time window W: QC increases from 12±6 to 359±17 for the central frequencies of 0.3 and 12.0 Hz when the lapse time window is W=10 sec and from 87±6 to 1177±87 for the same frequencies when W=95 sec (Fig. 6. On the basis of the QС values obtained for all the lapse time windows W empirical relationships of quality factors and frequencies are calculated according to [Mitchell, 1981], and values of quality factor Q0 at reference frequency f0 (f0=1 Hz and frequency parameter n (which is close to 1 and varies depending on the heterogeneity of the medium [Aki, 1981] are obtained. In this study, Q0 varies from 60±8 to 222±17, the frequency parameter ranges from 0.57±0.04 to 0.84±0.05, and the attenuation coefficient δ varies from 0.015 to 0.004 km–1, depending on W (Fig. 8; similar values of attenuation parameters are typical of regions with high tectonic activity [Mak et al., 2004].In the single-backscattering model, the dependence of the attenuation parameters from the lapse time window can be explained in terms

  5. Organizaciones sociales: nuevos actores políticos en Guerrero

    Directory of Open Access Journals (Sweden)

    Dulce María Quintero Romero

    2008-01-01

    Full Text Available Se retoma la discusión sobre la participación política como elemento fundamental en la configuración de esquemas de desarrollo. Se analiza Guerrero, una entidad con importante presencia histórica en las luchas nacionales, pero, sobre todo, un espacio en el que la pobreza, los cacicazgos locales y los abusos del poder estatal y federal han propiciado acciones de resistencia capaces de reconfigurar procesos organizativos novedosos, las cuales irrumpen con fuerza en el siglo XXI. Las organizaciones ciudadanas locales emergen en el escenario político en su lucha contra la impunidad y la búsqueda de justicia en el marco favorable de la acción medioambiental y de derechos humanos nacional e internacional.

  6. Seismic reflection-based evidence of a transfer zone between the Wagner and Consag basins: implications for defining the structural geometry of the northern Gulf of California

    Science.gov (United States)

    González-Escobar, Mario; Suárez-Vidal, Francisco; Hernández-Pérez, José Antonio; Martín-Barajas, Arturo

    2010-12-01

    This study examines the structural characteristics of the northern Gulf of California by processing and interpreting ca. 415 km of two-dimensional multi-channel seismic reflection lines (data property of Petróleos Mexicanos PEMEX) collected in the vicinity of the border between the Wagner and Consag basins. The two basins appear to be a link between the Delfín Superior Basin to the south, and the Cerro Prieto Basin to the north in the Mexicali-Imperial Valley along the Pacific-North America plate boundary. The seismic data are consistent with existing knowledge of four main structures (master faults) in the region, i.e., the Percebo, Santa María, Consag Sur, and Wagner Sur faults. The Wagner and Consag basins are delimited to the east by the Wagner Sur Fault, and to the west by the Consag Sur Fault. The Percebo Fault borders the western margin of the modern Wagner Basin depocenter, and is oriented N10°W, dipping (on average) ˜40° to the northeast. The trace of the Santa María Fault located in the Wagner Basin strikes N19°W, dipping ˜40° to the west. The Consag Sur Fault is oriented N14°W, and dips ˜42° to the east over a distance of 21 km. To the east of the study area, the Wagner Sur Fault almost parallels the Consag Sur Fault over a distance of ˜86 km, and is oriented N10°W with an average dip of 59° to the east. Moreover, the data provide new evidence that the Wagner Fault is discontinuous between the two basins, and that its structure is more complex than previously reported. A structural high separates the northern Consag Basin from the southern Wagner Basin, comprising several secondary faults oriented NE oblique to the main faults of N-S direction. These could represent a zone of accommodation, or transfer zone, where extension could be transferred from the Wagner to the Consag Basin, or vice versa. This area shows no acoustic basement and/or intrusive body, which is consistent with existing gravimetric and magnetic data for the region.

  7. Did Oligocene crustal thickening precede basin development in northern Thailand? A geochronological reassessment of Doi Inthanon and Doi Suthep

    Science.gov (United States)

    Gardiner, Nicholas J.; Roberts, Nick M. W.; Morley, Christopher K.; Searle, Michael P.; Whitehouse, Martin J.

    2016-01-01

    The Doi Inthanon and Doi Suthep metamorphic core complexes in northern Thailand are comprised of amphibolite-grade migmatitic gneisses mantled by lower-grade mylonites and metasedimentary sequences, thought to represent Cordilleran-style core complexes exhumed through the mobilization of a low-angle detachment fault. Previous studies have interpreted two metamorphic events (Late Triassic and Late Cretaceous), followed by ductile extension between the late Eocene and late Oligocene, a model which infers movement on the detachment at ca. 40 Ma, and which culminates in a rapid unroofing of the complexes in the early Miocene. The Chiang Mai Basin, the largest such Cenozoic Basin in the region, lies immediately to the east. Its development is related to the extension observed at Doi Inthanon and Doi Suthep, however it is not definitively dated, and models for its development have difficulty reconciling Miocene cooling ages with Eocene detachment movement. Here we present new in-situ LA-ICP-MS and SIMS U-Pb age data of zircon and monazite grains from gneiss and leucogranite samples taken from Doi Inthanon and Doi Suthep. Our new zircon data exhibit an older age range of 221-210 Ma, with younger ages of ca. 72 Ma, and 32-26 Ma. Our monazite data imply an older age cluster at 83-67 Ma, and a younger age cluster of 34-24 Ma. While our data support the view of Indosinian basement being reworked in the Cretaceous, they also indicate a late Eocene-Oligocene tectonothermal event, resulting in prograde metamorphism and anatexis. We suggest that this later event is related to localized transpressional thickening associated with sinistral movement on the Mae Ping Fault, coupled with thickening at the restraining bend of the Mae Yuan Fault to the immediate west of Doi Inthanon. Further, this upper Oligocene age limit from our zircon and monazite data would imply a younger Miocene constraint on movement of the detachment, which, when combined with the previously recorded Miocene

  8. Benthic macro red alga: A new possible bio-precursor of Jurassic mudstone source rocks in the northern Qaidam Basin, northwestern China

    Institute of Scientific and Technical Information of China (English)

    CAO Jian; BIAN LiZeng; HU Kai; LIU YunTian; WANG LiQun; YANG ShaoYong; CHEN Yan; PENG XiaoQun

    2009-01-01

    Whether benthic macroalga can be an Important type of bio-precursor of source rocks is a contentious Issue in source-rock studies, and has not been well understood. This paper represents a case study of Jurassic mudstone source rocks from the northern Qaidam Basin, northwestern China, in which the benthic macro red algae were recognized for the first time based on combined organic petrological and biomarker works. We found not only cystocarpa in the algae, representative of rhodophyta, but also diahopanes, which are diagnostic biomarkers of such algae. Thus, as many reservoired oils in the northern Qaidam Basin contain abundant diahopanes, it may indicate that the red algae have contributed to hydrocarbon accumulation. This was confirmed by integrated geological and geochemical analyses. Hence, this study provides new evidence for macroalga-generated hydrocarbons.

  9. Benthic macro red alga:A new possible bio-precursor of Jurassic mudstone source rocks in the northern Qaidam Basin,northwestern China

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Whether benthic macroalga can be an important type of bio-precursor of source rocks is a contentious issue in source-rock studies,and has not been well understood.This paper represents a case study of Jurassic mudstone source rocks from the northern Qaidam Basin,northwestern China,in which the benthic macro red algae were recognized for the first time based on combined organic petrological and biomarker works.We found not only cystocarps in the algae,representative of rhodophyta,but also diahopanes,which are diagnostic biomarkers of such algae.Thus,as many reservoired oils in the northern Qaidam Basin contain abundant diahopanes,it may indicate that the red algae have contributed to hydrocarbon accumulation.This was confirmed by integrated geological and geochemical analyses.Hence,this study provides new evidence for macroalga-generated hydrocarbons.

  10. Hydrology of mountainous areas in the upper Indus Basin, Northern Pakistan with the perspective of climate change.

    Science.gov (United States)

    Ahmad, Zulfiqar; Hafeez, Mohsin; Ahmad, Iftikhar

    2012-09-01

    Mountainous areas in the northern Pakistan are blessed by numerous rivers that have great potential in water resources and hydropower production. Many of these rivers are unexploited for their water resource potential. If the potential of these rivers are explored, hydropower production and water supplies in these areas may be improved. The Indus is the main river originating from mountainous area of the Himalayas of Baltistan, Pakistan in which most of the smaller streams drain. In this paper, the hydrology of the mountainous areas in northern Pakistan is studied to estimate flow pattern, long-term trend in river flows, characteristics of the watersheds, and variability in flow and water resource due to impact of climate change. Eight watersheds including Gilgit, Hunza, Shigar, Shyok, Astore, Jhelum, Swat, and Chitral, Pakistan have been studied from 1960 to 2005 to monitor hydrological changes in relation to variability in precipitation, temperature and mean monthly flows, trend of snow melt runoff, analysis of daily hydrographs, water yield and runoff relationship, and flow duration curves. Precipitation from ten meteorological stations in mountainous area of northern Pakistan showed variability in the winter and summer rains and did not indicate a uniform distribution of rains. Review of mean monthly temperature of ten stations suggested that the Upper Indus Basin can be categorized into three hydrological regimes, i.e., high-altitude catchments with large glacierized parts, middle-altitude catchments south of Karakoram, and foothill catchments. Analysis of daily runoff data (1960-2005) of eight watersheds indicated nearly a uniform pattern with much of the runoff in summer (June-August). Impact of climate change on long-term recorded annual runoff of eight watersheds showed fair water flows at the Hunza and Jhelum Rivers while rest of the rivers indicated increased trends in runoff volumes. The study of the water yield availability indicated a minimum trend in

  11. Growth of the Zagros Fold-Thrust Belt and Foreland Basin, Northern Iraq, Kurdistan

    Science.gov (United States)

    Koshnaw, Renas; Horton, Brian; Stockli, Daniel; Barber, Douglas; Ghalib, Hafidh; Dara, Rebwar

    2016-04-01

    The Zagros orogenic belt in the Middle Eastern segment of the Alpine-Himalayan system is among the youngest seismically active continental collision zones on Earth. However, due to diachronous and incremental collision, the precise ages and kinematics of shortening and deposition remain poorly understood. The Kurdistan region of the Zagros fold-thrust belt and foreland basin contains well-preserved Neogene wedge-top and foredeep deposits that include clastic nonmarine fill of the Upper Fars, Lower Bakhtiari, and Upper Bakhtiari Formations. These deposits record significant information about orogenic growth, fold-thrust dynamics, and advance of the deformation front. Thermochronologic and geochronologic data from thrust sheets and stratigraphic archives combined with local earthquake data provide a unique opportunity to address the linkages between surface and subsurface geologic relationships. This research seeks to constrain the timing and geometry of exhumation and deformation by addressing two key questions: (1) Did the northwestern Zagros fold-thrust belt evolve from initial thin-skinned shortening to later thick-skinned deformation or vice-versa? (2) Did the fold-thrust belt advance steadily under critical/supercritical wedge conditions involving in-sequence thrusting or propagate intermittently under subcritical conditions with out-of-sequence deformation? From north to south, apatite (U-Th)/He ages from the Main Zagros Thrust, the Mountain Front Flexure (MFF), and additional frontal thrusts suggest rapid exhumation by ~10 Ma, ~5 Ma, and ~8 Ma respectively. Field observations and seismic sections indicate progressive tilting and development of growth strata within the Lower Bakhtiari Formation adjacent to the frontal thrusts and within the Upper Bakhtiari Formation near the MFF. In the Kurdistan region of Iraq, a regional balanced cross section constrained by new thermochronometric results, proprietary seismic reflection profiles, and earthquake hypocenters

  12. Middle to late Cenozoic basin evolution in the western Alborz Mountains: Implications for the onset of collisional deformation in northern Iran

    OpenAIRE

    Guest, Bernard; Horton, Brian K.; Axen, Gary J.; Hassanzadeh, Jamshid; MCINTOSH, William C.

    2007-01-01

    Oligocene-Miocene strata preserved in synclinal outcrop belts of the western Alborz Mountains record the onset of Arabia-Eurasia collision-related deformation in northern Iran. Two stratigraphic intervals, informally named the Gand Ab and Narijan units, represent a former basin system that existed in the Alborz. The Gand Ab unit is composed of marine lagoonal mudstones, fluvial and alluvial-fan clastic rocks, fossiliferous Rupelian to Burdigalian marine carbonates, and basalt flows yielding ^...

  13. An investigation of the genus Mesacanthus (Chordata: Acanthodii) from the Orcadian Basin and Midland Valley areas of Northern and Central Scotland using traditional morphometrics

    OpenAIRE

    Baron, Matthew G.

    2015-01-01

    Mesacanthus is a common and speciose genus of acanthodian fish from Lower Old Red Sandstone and Middle Old Red Sandstone assemblages (representing the Lower Devonian and Middle Devonian respectively) and is well represented in many palaeoichthyology collections in the UK. Based upon descriptions given during the 19th century, specimens of the genus Mesacanthus from the Orcadian Basin and Midland Valley areas of Northern and Central Scotland have historically been referred to a number of diffe...

  14. Stable isotope record of Eemian seasonal temperature from MIS 5e tufa stromatolite; Somme Basin, Northern France

    Directory of Open Access Journals (Sweden)

    J. Dabkowski

    2013-03-01

    Full Text Available In many modern to sub-fossil deposits tufa formations, very well crystallised deposits called stromatolites are preserved. These are often strongly laminated deposits, the laminae linked to seasonal climatic and environmental variations. Where found in fossil tufas such deposits have huge potential as high resolution archives of Pleistocene climate. One of the first investigations of this type has been performed on a 2.5 cm-radius stromatolite from the Eemian sequence of Caours (Somme Basin, Northern France, where precise observations in thin section have been combined with intra-lamina δ18O and δ13C analyses. Independent interpretations of petrographical and geochemical data are strongly coherent and demonstrate a clear seasonal signal. Moreover, as δ18O is temperature dependent, we have quantified likely maximum water temperature variations between summer and winter at Caours. A small mismatch between the δ18O derived temperature values and the typical modern range is observed, which may reflect a real difference between modern and Eemian temperature seasonality. This study supports previous investigations performed on a laminated tufa from central Greece and clearly confirms the potential of tufa stromatolites as records of seasonal climatic information and for the quantification of riverine water temperature variations.

  15. Quantification and multivariate analysis of water erosion in the Mediterranean region. A case study of the Isser basin. northern Algeria

    Science.gov (United States)

    Zeggane, Houari; Boutoutaou, Djamel

    2016-07-01

    In the Mediterranean region, the specifisity of erosion stems from a particularly contrasted climate, drought, and from summer and autumn severe thunderstorms. The process of erosion generates substantial loss of soil and affects any kind of crop. The adopted approach aims to establish regression models in order to highlight the relationship between solid and liquid flows at four measurement stations in the Isser catchement area, northern Ageria. The Power Model seems to explain this relationship. The quantification and temporal analysis of solid matter transport showed that the rates of erosion are high along the study area. The annual mean solid matter transport for the whole basin is about 2 200 t/km2.year, of which the main part is recorded in autumn during peak flows. The different factors involved in the process of water erosion are determined in advance in order to establish a model between the predictand variable, which is the specific erosion, and other predictors. Besides, a functional relationship has been highlighted between water erosion and the mean slope, the drainage density and the lithology index.

  16. Reconsidering the taxonomy of the Black-Faced Uacaris, Cacajao melanocephalus group (Mammalia: Pitheciidae), from the northern Amazon Basin.

    Science.gov (United States)

    Ferrari, Stephen F; Guedes, Patrícia G; Figueiredo-Ready, Wilsea M B; Barnett, Adrian A

    2014-09-24

    The black-faced uacaris are a poorly known group of platyrrhine monkeys from the Rio Negro basin in northwestern Amazonia. Originally described as two distinct species-Cacajao melanocephalus (Humboldt 1812) and Cacajao ouakary (Spix 1823)-from opposite banks of the Negro, they were treated as a single species until the end of the twentieth century, when molecular studies reconfirmed their status as true species. One of these studies not only nominated a third (northern) species, Cacajao ayresi Boubli et al. 2008, but also identified C. ouakary as a junior synonym of C. melanocephalus, resulting in the introduction of a new nomen, Cacajao hosomi Boubli et al. 2008. In the present study, additional evidence on morphological and zoogeographic variables is analyzed, which indicates that C. ouakary should be reinstated, and supports the nomination of a neotype of C. melanocephalus. The molecular and zoogeographic data on the species status of the ayresi form are also re-assessed, leading to the conclusion that, on the basis of the evidence available at the present time, this form should be considered a subspecies of C. melanocephalus. A new taxonomic arrangement is proposed, which recognizes two species, C. ouakary and C. melanocephalus, the latter with two subspecies, C. m. melanocephalus and C. m. ayresi.

  17. Simulation experiment on hydrocarbon generating potential of various source rocks on the northern margin of the Qaidam Basin, Qinghai, China

    Institute of Scientific and Technical Information of China (English)

    LI Xin; WANG Dongliang; LIU Baoquan; REN Chunling; GUO Jianying; SU Xuefeng; WANG Jian

    2008-01-01

    The northern margin of the Qaidam Basin is one of the main oil-gas exploration areas in western China, where source rocks are composed mostly of Middle and Lower Jurassic dark mud shale, carbargillite and coal. A large number of subsurface and outcrop samples differing in lithology with different types of organic matter were selected for resource evaluation, research and calculation. And among them, 13 samples were used for simulation experiment on hydrocarbon generating potential of various source rocks. At first, two kinds of heating modes were compared through simulation experiment, including single temperature-step heating and continual heating. Perhaps, the process of hydrocarbon generation and expulsion occurred naturally between a close system and an open system. In addition, the first heating mode was convenient, and all its reaction products were involved in the whole thermal evolution, and the final simulation experimental results were basically in consistency with the natural evolution trend. Therefore, the first heating mode was adopted and the hydrocarbon yield of every sample was worked out. According to the type and lithology of organic matter and the hydrocarbon yield of samples for simulation experiment, hydrocarbon generation and expulsion mode with three kinds of lithology and five types of source rock has been established to provide the basis for hydrocarbon generation evaluation, research and resource calculation.

  18. Hydrogeochemistry of co-occurring geogenic arsenic, fluoride and iodine in groundwater at Datong Basin, northern China.

    Science.gov (United States)

    Pi, Kunfu; Wang, Yanxin; Xie, Xianjun; Su, Chunli; Ma, Teng; Li, Junxia; Liu, Yaqing

    2015-12-30

    Abnormal levels of co-occurring arsenic (As), fluorine (F) and iodine (I) in groundwater at Datong Basin, northern China are geochemically unique. Hydrochemical, (18)O and (2)H characteristics of groundwater were analyzed to elucidate their mobilization processes. Aqueous As, F and I ranged from 5.6 to 2680 μg/L, 0.40 to 3.32 mg/L and 10.1 to 186 μg/L, respectively. High As, F and I groundwater was characterized by moderately alkaline, high HCO3(-), Fe(II), HS(-) and DOC concentrations with H3AsO3, F(-) and I(-) as the dominant species. The plots of δ(18)O values and Cl/Br ratios versus Cl(-) concentration demonstrate build-up of more oxidizing conditions and precipitation of carbonate minerals induced by vertical recharge and intensive evaporation facilitate As retention to Fe (hydr) oxides, but enhance F and I mobilization from host minerals. Under reducing conditions, As and I can be simultaneously released via reductive dissolution of Fe (hydr) oxides and reduction of As(V) and I(V) while F migration may be retarded due to effects of dissolution-precipitation equilibria between carbonate minerals and fluorite. With the prevalence of sulfate-reducing condition and lowering of HCO3(-) concentration, As and I may be sequestered by Fe(II) sulfides and F is retained to fluorite and on clay mineral surfaces. PMID:26282220

  19. Thick-skinned Contractional Salt Structures in the Kuqa Depression, the Northern Tarim Basin: Constraints from Physical Experiments

    Institute of Scientific and Technical Information of China (English)

    YU Yixin; TANG Liangjie; YANG Wenjing; JIN Wenzheng; PENG Gengxin; LEI Ganglin

    2008-01-01

    Thick-skinned contractional salt structures are widely developed in the western Kuqa depression, northern Tarim basin. To understand the mechanisms that govern the development of these structures, physical experiments are conducted and the results show that they are largely governed by the activities of basement faults and the forming of paleo-uplifts and basement slopes. The model materials in this study are dry sand, vaseline and plasticene (or hard foam), simulating the suprasalt, salt, and subsalt layers respectively. The experiments show that, due to the activities of basement faults and the forming of the paleo-uplifts, salt bodies usually accumulate and thicken significantly on the middle top of the paleo-uplifts which are constrained by the pre-exiting boundary faults. The development of large-scale thrust faults and salt nappes is favored by the basement slops with larger dips. The experiments also conclude that differential structural deformation could occur between the subsalt and suprasalt layers because of the presence of salt layers. Their geometries and the locations of structural highs are different, despite of the great similarities in the uplifted areas. The pierced salt diapir is not observed in the experiments, which indicates that the contractional shortening does not effectively accelerate the development of the salt diapir.

  20. Seismicity in the Raton Basin of Southern Colorado and Northern New Mexico, USA, as Recorded by a Local Array

    Science.gov (United States)

    Macartney, H.

    2013-12-01

    Microseismic events (Basin of southern Colorado and northern New Mexico, USA, over a period of 18 months following the occurrence of a 5.3 magnitude event near Trinidad CO in August, 2011. Micro-seismicity was observed in the region, concentrated in six clusters at depths of 6-12 km below the surface, deep in the basement, and 4-10 km below zones used for fluid disposal from an overlying coalbed methane natural gas field. Clusters are separated from disposal zones by large aseismic intervals. The clusters are mixed in character; both planar and elongate amorphous swarms, some continually active and some as short-lived bursts, with larger initial events tending to occur deeper and smaller after-shocks propagating upward and away from the nucleating events. Magnitudes range between 0 and 3, with the vast majority being less than 1.5M. Most of the clusters have no disposal wells above and no seismic activity was correlated with changes in fluid disposal. No seismicity was detected from hydraulic fracturing operations.

  1. Winter and spring mixing depths affect the trophic status and composition of phytoplankton in the northern meromictic basin of Lake Lugano

    Directory of Open Access Journals (Sweden)

    Marco SIMONA

    2003-08-01

    Full Text Available The trophic state of Lake Lugano is still too high to be acceptable, despite extensive recovery measures undertaken in recent decades which have resulted in a reduction of the external phosphorus load to the deepest of the lake's basins (northern basin; Zmax=286 m to fairly acceptable values. Since meromixis was established in the middle of last century, the deep hypolimnion of the northern basin (the layer between ca 100 m and the bottom has contained high quantities of nutrients (especially phosphorus which are a major potential source of internal load. When there are particularly strong winter mixing events, a portion of this phosphorus reserve is redistributed along the upper water column (0-100 m. The impact of meteo-climatic conditions on the plankton biocenosis were analysed using data collected in the northern basin (Gandria station during the three-year period 1998-2000. The phytoplankton composition, which is typical of eutrophicated waters, shows marked interannual variations, also depending on the degree of mixing of the waters at the start of the vegetative period. Though there is no steady pattern of typical dominant species / master species in the lake, there is a seasonal succession characterised by a marked development of diatoms in spring, and a predominance of chlorophyceans and cyanobacteria in summer and autumn. Under present conditions, the mechanisms of internal replenishment of nutrients towards the euphotic layer, due to the phenomena of late winter and spring mixing, constitute a significant source of nutrients for the spring and summer growth of phytoplankton. On the other hand, pronounced mixing phenomena, like those occurring in the two-year period 1999-2000, can reduce the hypolimnetic nutrient reserves and cause a decrease in the trophic potential of the basin, contrasting with an increase in algal biomass in the euphotic zone.

  2. Mesozoic deformation in the Chaoshan Depression of the Pearl River Mouth Basin, northern South China Sea

    Science.gov (United States)

    Zhang, Jiangyang; Sun, Zhen; Zhang, Yunfan; Li, Fucheng

    2016-05-01

    Newly collected, high resolution multi-beam sonar data are combined with previous bathymetry data to produce an improved bathymetric map of Shatsky Rise oceanic plateau. Bathymetry data show that two massifs within Shatsky Rise are immense central volcanoes with gentle flank slopes declining from a central summit. Tamu Massif is a slightly elongated, dome-like volcanic edifice; Ori Massif is square shaped and smaller in area. Several down-to-basin normal faults are observed on the western flank of the massifs but they do not parallel the magnetic lineations, indicating that these faults are probably not related to spreading ridge faulting. Moreover, the faults are observed only on one side of the massifs, which is contrary to expectations from a mechanism of differential subsidence around the massif center. Multi-beam data show many small secondary cones with different shapes and sizes that are widely-distributed on Shatsky Rise massifs, which imply small late-stage magma sources scattered across the surface of the volcanoes in the form of lava flows or explosive volcanism. Erosional channels occur on the flanks of Shatsky Rise volcanoes due to mass wasting and display evidence of down-slope sediment movement. These channels are likely formed by sediments spalling off the edges of summit sediment cap.

  3. Structural framework and its evolution in Chasang area of Qiangtang Basin in northern Tibetan

    Institute of Scientific and Technical Information of China (English)

    刘池洋; 杨兴科; 任战利; 赖绍聪; 陈刚; 赵红格; 魏永佩; 郑孟林; 王成善

    2001-01-01

    Through comprehensive research on the various geophysical and geological data acquired recently, we consider that the Chasang area in the western uplift of Qiangtang is a huge south-dipping block which is overlapped by several east-west trending blocks rather than a simple and palaeo-doming existing for a long time. The structural and geophysical features of the area, which only alone limited between Shuanghu and Rongma districts, are of no regional significance. Their development is closely related with the approximately south-north trending transform faults developed during the Mesozoic era on the east and west sides of the area and their later continuous movement. The compressing, overlapping and uplifting of the Chasang area began at the stage of reversing of the Qiangtang Basin during the Lower Cretaceous, which is in direct relation with Bangonghu-Dingqing limited ocean’s closure and the convergence of the neighboring blocks. The compression and overlapping of the area have further developed and re

  4. Genetic Relationship between Natural Gas Dispersal Zone and Uranium Accumulation in the Northern Ordos Basin, China

    Institute of Scientific and Technical Information of China (English)

    GAN Huajun; XIAO Xianming; LU Yongchao; JIN Yongbin; TIAN Hui; LIU Dehan

    2007-01-01

    The Ordos Basin is well-known for the coexistence of oil, natural gas, coal and uranium. However, there has been little research to discuss the genetic relationship between them. In this paper, a case study of the Zaohuohao area in Dongsheng, Inner Mongolia, China, is conducted to investigate the genetic relationship between the natural gas and the uranium accumulation. Fluid inclusion data from the uranium-bearing sandstone samples indicate that the fluid inclusions formed in a gas-water transition zone. Using the homogeneous temperatures of aqueous inclusions coeval with hydrocarbonbearing inclusions, combined with the buried history and paleo-temperature data, the gas-water transition zone reached the area at about 110 Ma. On the basis of this, the contents of Uranium (U)and Total Organic Carbon (TOC) of the samples were analyzed, and there was no obvious relation between them. With regard to the available data from both publications and this study, it is found that the U mineralization has a spatiotemporal accordance with the gas-water dispersal zone. Thus, it is believed that the natural gas in the gas-water zone is an effective reducer to the U-bearing ground water abundant in oxygen, which is the main factor to U accumulation. This result can be used as the reference to the U mines predicting and prospecting.

  5. Retrogressive failures recorded in mass transport deposits in the Ursa Basin, Northern Gulf of Mexico

    Science.gov (United States)

    Sawyer, Derek E.; Flemings, Peter B.; Dugan, Brandon; Germaine, John T.

    2009-10-01

    Clay-rich mass transport deposits (MTDs) in the Ursa Basin, Gulf of Mexico, record failures that mobilized along extensional failure planes and transformed into long runout flows. Failure proceeded retrogressively: scarp formation unloaded adjacent sediment causing extensional failure that drove successive scarp formation updip. This model is developed from three-dimensional seismic reflection data, core and log data from Integrated Ocean Drilling Project (IODP) Expedition 308, and triaxial shear experiments. MTDs are imaged seismically as low-amplitude zones above continuous, grooved, high-amplitude basal reflections and are characterized by two seismic facies. A Chaotic facies typifies the downdip interior, and a Discontinuous Stratified facies typifies the headwalls/sidewalls. The Chaotic facies contains discontinuous, high-amplitude reflections that correspond to flow-like features in amplitude maps: it has higher bulk density, resistivity, and shear strength, than bounding sediment. In contrast, the Discontinuous Stratified facies contains relatively dim reflections that abut against intact pinnacles of parallel-stratified reflections: it has only slightly higher bulk density, resistivity, and shear strength than bounding sediment, and deformation is limited. In both facies, densification is greatest at the base, resulting in a strong basal reflection. Undrained shear tests document strain weakening (sensitivity = 3). We estimate that failure at 30 meters below seafloor will occur when overpressure = 70% of the hydrostatic effective stress: under these conditions soil will liquefy and result in long runout flows.

  6. 26Al/10Be burial dating of Xujiayao-Houjiayao site in Nihewan Basin, northern China.

    Directory of Open Access Journals (Sweden)

    Hua Tu

    Full Text Available The Xujiayao-Houjiayao site in Nihewan Basin is among the most important Paleolithic sites in China for having provided a rich collection of hominin and mammalian fossils and lithic artifacts. Based on biostratigraphical correlation and exploratory results from a variety of dating methods, the site has been widely accepted as early Upper Pleistocene in time. However, more recent paleomagnetic analyses assigned a much older age of ∼500 ka (thousand years. This paper reports the application of 26Al/10Be burial dating as an independent check. Two quartz samples from a lower cultural horizon give a weighted mean age of 0.24 ± 0.05 Ma (million years, 1σ. The site is thus younger than 340 ka at 95% confidence, which is at variance with the previous paleomagnetic results. On the other hand, our result suggests an age of older than 140 ka for the site's lower cultural deposits, which is consistent with recent post-infrared infrared stimulated luminescence (pIR-IRSL dating at 160-220 ka.

  7. Rayleigh-wave ellipticity and shallow structure in sedimentary basins: the Po Plain (northern Italy)

    Science.gov (United States)

    Berbellini, A.; Morelli, A.; Ferreira, A. M. G.

    2015-12-01

    The amplitude ratio between horizontal and vertical components of Rayleigh waves (also known as ellipticity) is in principle uniquely sensitive to local earth structure beneath each recording station. Rayleigh wave ellipticity is mostly influenced by the shallowest layers, so it can be effectively used to infer the structure of the uppermost crust, with particular relevance for sedimentary environments. We implement an automatic method to measure Rayleigh wave ellipticity, and extensively apply it to teleseismic records from the northern part of Italy, for a period range between 10s and 130s. As expected, no appreciable correlation with epicenter distance or azimuth can be seen, but rather a strong correlation with local structure: generally high horizontal to vertical amplitude ratios are seen in sedimentary settings, with respect to Alpine and Apenninic crystalline-rock terrains. We verify that shortest usable period may be limited by very low shear-wave velocity in shallow sediments, when the assumed retrograde elliptical particle motion polarisation for the fundamental mode breaks off. The highly non-linear sensitivity of frequency-dependent ellipticity curves can then be inverted using a direct search method to infer shear wave velocity profiles below stations. By comparing our results with local a priori geological information we show that robust information can indeed be retrieved.

  8. Preliminary Paleomagnetic Results From Tertiary Rocks of Sedimentary Basins in Northern Vietnam and Tectonic Implications

    Science.gov (United States)

    Zhao, X.; Liu, Z.; Le, K.; Zhao, Y.; Hoang, V.; Phan, D.

    2013-12-01

    The South China Sea (SCS) is a classical representative of western Pacific marginal seas and contains records of Cenozoic tectonic events of SE Asia. The SCS has been at the center stage of many first-order tectonic and paleoclimatic events since the Mesozoic. One clear way to evaluate the relationship between tectonic uplift and climate is to study the resulting changes in marginal sea strata. To this end, we will conduct an integrated paleomagnetic and stratigraphic investigation on Tertiary strata from Phu Tho and Yen Bai provinces, northern Vietnam to help understand the causal linkages among geological and tectonic events and their consequences related to the SCS evolution. We will collect paleomagnetic samples at sections where the most continuous, complete, and best preserved Eocene-Miocene successions. Standard paleomagnetic field tests, such as the fold, reversal, and conglomerate tests will be used to determine the relative age of the magnetization. In addition to detailed thermal and alternating field demagnetization and analysis, selected samples will also be subjected to several rock magnetic analyses to identify magnetic carriers in the rocks. In particular, the hysteresis parameters Jrs/Js and Hcr /Hc ratios will enable us to apply techniques for detecting low-temperature remagnetization of sedimentary rocks. Preliminary finding of this ongoing project will be presented.

  9. Understanding the Hydrogeology of Raya Valley Basin, Northern Ethopia Using Stablee Isotopes of Water

    International Nuclear Information System (INIS)

    The Raya valley is located in the northern part of Ethiopia. The study area is connected to the Ethiopian rift system and bounded by the Ethiopian plateau to the west and Cherecher Mountain to the east. The study area is characterized by its semiarid climate. In order to investigate isotopic characteristics of different water bodies and groundwater recharge, water samples were collected in the summer rainy season and analysed for stable isotopes of oxygen and hydrogen by a laser based liquid water isotope analyser. Most of the groundwater samples are plotted just below the LMWL, which indicates that the origin is meteoric water and affected by secondary evaporation. There are highly depleted water samples in the eastern side of the study area, which could be attributed to the existence of palaeowater. Groundwater is mainly recharged by rain water and intermittent rivers. Open water bodies (the lake Ashenge and Gerjale swamp area) show enrichment due to high rate of evaporation. Isotopically the flood water in the highland aarea is depleted as a result of high rate of rainfall, high humidity and low rate of evaporation. (author)

  10. The opening of the Woodlark Basin, subduction of the Woodlark spreading system, and the evolution of Northern Melanesia since mid-pliocene time

    Science.gov (United States)

    Weissel, Jeffrey K.; Taylor, Brian; Karner, Garry D.

    1982-08-01

    Magnetic anomaly and seismological data define segments of active seafloor spreading and associated magnetic lineations trending ENE in the Woodlark Basin. The total opening rate has been approximately 6 cm/yr for the last 1 m.y. Spreading rates diminish by over 10% from east to west along the Woodlark spreading system implying a pole of current opening 15°-20° to the west. Commencement of seafloor spreading in the basin has apparently been time-transgressive, beginning prior to 3.5 m.y. in the east, and at successively later times to the west. Earthquake focal mechanisms and geological evidence suggest that the land areas bounding the western end of the Woodlark Basin are undergoing tensional deformation. We believe that eventually the Woodlark Basin plate boundary will propagate westward through the d'Entrecasteaux Islands into the Papuan peninsula. Hitherto unreported shallow seismicity associated with the northern margin of the NE-trending section of the Woodlark Rise probably reflects partial decoupling of the Woodlark and Solomon basins, possibly due to mechanical difficulties in subducting the young Woodlark lithosphere. Analysis of the relative motions between the Solomon, Indo-Australian, and Pacific plates shows that the Woodlark spreading system has been subducted at high rates (> 10 cm/yr) beneath the Solomon Islands during the opening of the Woodlark Basin. Several tectonic and geological features limited to the region of interaction of the Woodlark Basin with the Solomon Trench and arc may be symptomatic of ridge subduction. These features include high heat flow in the Solomon Trench, which shoals to 4 km; low levels of seismicity and only shallow hypocenters; and voluminous eruptions of high {K 2O }/{TiO 2} olivine basalts and basaltic andesites extremely close to the trench axis. This close association in space and time of an unusual volcanic suite with ridge subduction implies a strong dependence of the petrogenesis on the tectonic regime. A

  11. Analyses of infrequent (quasi-decadal) large groundwater recharge events in the northern Great Basin: Their importance for groundwater availability, use, and management

    Science.gov (United States)

    Gangopadhyay, Subhrendu; Masbruch, Melissa D.; Pruitt, Tom; Rumsey, Christine; Susong, David D.

    2016-01-01

    There has been a considerable amount of research linking climatic variability to hydrologic responses in the western United States. Although much effort has been spent to assess and predict changes in surface water resources, little has been done to understand how climatic events and changes affect groundwater resources. This study focuses on characterizing and quantifying the effects of large, multiyear, quasi-decadal groundwater recharge events in the northern Utah portion of the Great Basin for the period 1960–2013. Annual groundwater level data were analyzed with climatic data to characterize climatic conditions and frequency of these large recharge events. Using observed water-level changes and multivariate analysis, five large groundwater recharge events were identified with a frequency of about 11–13 years. These events were generally characterized as having above-average annual precipitation and snow water equivalent and below-average seasonal temperatures, especially during the spring (April through June). Existing groundwater flow models for several basins within the study area were used to quantify changes in groundwater storage from these events. Simulated groundwater storage increases per basin from a single recharge event ranged from about 115 to 205 million cubic meters. Extrapolating these amounts over the entire northern Great Basin indicates that a single large quasi-decadal recharge event could result in billions of cubic meters of groundwater storage. Understanding the role of these large quasi-decadal recharge events in replenishing aquifers and sustaining water supplies is crucial for long-term groundwater management.

  12. Assessment of River Habitat Quality in the Hai River Basin, Northern China

    Directory of Open Access Journals (Sweden)

    Yuekui Ding

    2015-09-01

    Full Text Available We applied a river habitat quality (RHQ assessment method to the Hai River Basin (HRB; an important economic centre in China; to obtain baseline information for water quality improvement; river rehabilitation; and watershed management. The results of the assessment showed that the river habitat in the HRB is seriously degraded. Specifically; 42.41% of the sites; accounting for a river length of 3.31 × 104 km; were designated poor and bad. Habitat in the plain areas is seriously deteriorated; and nearly 50% of the sites; accounting for a river length of 1.65 × 104 km; had either poor or bad habitats. River habitat degradation was attributable to the limited width of the riparian zone (≤5 m; lower coverage of riparian vegetation (≤40%; artificial land use patterns (public and industrial land; frequent occurrence of farming on the river banks and high volumes of solid waste (nearly 10 m3; single flow channels; and rare aquatic plants (≤1 category. At the regional scale; intensive artificial land use types caused by urbanization had a significant impact on the RHQ in the HRB. RHQ was significantly and negatively correlated with farmland (r = 1.000; p < 0.01 and urban land (r = 0.998; p < 0.05; and was significantly and positively correlated with grassland and woodland (r = 1.000; p < 0.01. Intensive artificial land use; created through urbanization processes; has led to a loss of the riparian zone and its native vegetation; and has disrupted the lateral connectivity of the rivers. The degradation of the already essentially black rivers is exacerbated by poor longitudinal connectivity (index of connectivity is 2.08–16.56; caused by reservoirs and sluices. For river habitat rehabilitation to be successful; land use patterns need to be changed and reservoirs and sluices will have to be regulated.

  13. Assessment of River Habitat Quality in the Hai River Basin, Northern China.

    Science.gov (United States)

    Ding, Yuekui; Shan, Baoqing; Zhao, Yu

    2015-09-01

    We applied a river habitat quality (RHQ) assessment method to the Hai River Basin (HRB); an important economic centre in China; to obtain baseline information for water quality improvement; river rehabilitation; and watershed management. The results of the assessment showed that the river habitat in the HRB is seriously degraded. Specifically; 42.41% of the sites; accounting for a river length of 3.31 × 10⁴ km; were designated poor and bad. Habitat in the plain areas is seriously deteriorated; and nearly 50% of the sites; accounting for a river length of 1.65 × 10⁴ km; had either poor or bad habitats. River habitat degradation was attributable to the limited width of the riparian zone (≤5 m); lower coverage of riparian vegetation (≤40%); artificial land use patterns (public and industrial land); frequent occurrence of farming on the river banks and high volumes of solid waste (nearly 10 m³); single flow channels; and rare aquatic plants (≤1 category). At the regional scale; intensive artificial land use types caused by urbanization had a significant impact on the RHQ in the HRB. RHQ was significantly and negatively correlated with farmland (r = 1.000; p land (r = 0.998; p land use; created through urbanization processes; has led to a loss of the riparian zone and its native vegetation; and has disrupted the lateral connectivity of the rivers. The degradation of the already essentially black rivers is exacerbated by poor longitudinal connectivity (index of connectivity is 2.08-16.56); caused by reservoirs and sluices. For river habitat rehabilitation to be successful; land use patterns need to be changed and reservoirs and sluices will have to be regulated. PMID:26393628

  14. Subsurface structure and stratigraphy of the northwest end of the Turkana Basin, Northern Kenya Rift, as revealed by magnetotellurics and gravity joint inversion

    Science.gov (United States)

    Abdelfettah, Yassine; Tiercelin, Jean-Jacques; Tarits, Pascal; Hautot, Sophie; Maia, Marcia; Thuo, Peter

    2016-07-01

    In order to understand the subsurface stratigraphy and structure of the northwest end of the Turkana Basin, Northern Kenya Rift, we used 2-D joint inversion of magnetotelluric (MT) and gravity data acquired along 3 profiles perpendicular to the main Murua Rith-Lapur Rift Border Fault. The regional geology is characterized by a basement of Precambrian age overlain by a ≤500-m thick sandstone formation named the Lapur Sandstone of upper Cretaceous-lower Eocene in age, covered by thick rhyolitic and basaltic lavas of late Eocene-middle Miocene age, known as the "Turkana Volcanics". Final interpretation of the resistivity and density models, until 5 km depth, obtained by the joint inversion approach confirms the previous general knowledge about the half-graben geometry of the northern part of the Turkana Basin. The main Murua Rith-Lapur Rift Border Fault is well identified by both gravity and MT. At least, two other important secondary faults without surface expression are also identified. A new small half-graben basin, named the Kachoda Basin, parallel to the main Turkana Basin and filled by 1.5 km of sediments, has been also characterized. This study also highlights strong thickness variations of the three main geological units that could be expected in the subsurface of the Turkana Basin. For example, the sedimentary Nachukui and Kibish Formations reach up to >3 km in thickness at the eastern end of the north and central profiles. Lateral variations of the topography of the Precambrian basement are also evidenced. Conceptual geological models, which result from the combination of the obtained density and resistivity models as well as from geological and reflection seismic data, are proposed. In such an area of intensive and promising oil exploration, these models are essential in terms of identification of reservoirs, source rocks and trapping mechanisms.

  15. Aerosol chemistry above an extended Archipelago of the Eastern Mediterranean basin during strong northern winds

    Directory of Open Access Journals (Sweden)

    E. Athanasopoulou

    2015-03-01

    Full Text Available Detailed aerosol chemical predictions by a carefully designed model system (i.e. PMCAMx, WRF, GEOS-CHEM, along with airborne and ground-based observations, are presented and analyzed over a wide domain covering the Aegean Archipelago. The studied period is ten successive days during the summer of 2011, characterized by the most frequent prevailing wind conditions (Etesian regime. The submicron aerosol load in the lower troposphere above the Archipelago (< 2.2 km altitude is homogenously enriched in sulfate (average modeled and measured submicron sulfate of 5.5 and 5.8 μg m−3, respectively, followed by organics (2.3 and 4.4 μg m−3 and ammonium (1.5 and 1.7 μg m−3. Aerosol concentrations smoothly decline aloft, reaching lower values (< 1 μg m−3 above 4.2 km altitude. Model performance is found good (according the selected evaluation criteria for sulfate, ammonium, chloride, elemental carbon, organic carbon and total PM10 mass concentration, indicating a satisfactory representation of the aerosol chemistry and precursors. Higher model discrepancies are confined to the highest (e.g. peak sulfate values and lowest ends (e.g. nitrate of the airborne aerosol mass size distribution, as well as in airborne organic concentrations (model underestimation around 50%. The latter is most probably related to the intense fire activity upwind the Archipelago (i.e. Balkan area and Black Sea coastline, which is not represented in the current model application. Overall, the model system shows the best agreement with observations under strong northeastern winds over the Archipelago and up to 2.2 km altitude. The activation of the chemical ageing of biogenic particles is suggested to be used for the aerosol chemistry module, when treating organics in a sufficient nitrogen and sulfate-rich environment, such as that over the Aegean basin. More than 70% of the predicted aerosol mass over the Aegean Archipelago during a representative Etesian episode is

  16. RECONNAISSANCE ASSESSMENT OF CO2 SEQUESTRATION POTENTIAL IN THE TRIASSIC AGE RIFT BASIN TREND OF SOUTH CAROLINA, GEORGIA, AND NORTHERN FLORIDA

    Energy Technology Data Exchange (ETDEWEB)

    Blount, G.; Millings, M.

    2011-08-01

    A reconnaissance assessment of the carbon dioxide (CO{sub 2}) sequestration potential within the Triassic age rift trend sediments of South Carolina, Georgia and the northern Florida Rift trend was performed for the Office of Fossil Energy, National Energy Technology Laboratory (NETL). This rift trend also extends into eastern Alabama, and has been termed the South Georgia Rift by previous authors, but is termed the South Carolina, Georgia, northern Florida, and eastern Alabama Rift (SGFAR) trend in this report to better describe the extent of the trend. The objectives of the study were to: (1) integrate all pertinent geologic information (literature reviews, drilling logs, seismic data, etc.) to create an understanding of the structural aspects of the basin trend (basin trend location and configuration, and the thickness of the sedimentary rock fill), (2) estimate the rough CO{sub 2} storage capacity (using conservative inputs), and (3) assess the general viability of the basins as sites of large-scale CO{sub 2} sequestration (determine if additional studies are appropriate). The CO{sub 2} estimates for the trend include South Carolina, Georgia, and northern Florida only. The study determined that the basins within the SGFAR trend have sufficient sedimentary fill to have a large potential storage capacity for CO{sub 2}. The deeper basins appear to have sedimentary fill of over 15,000 feet. Much of this fill is likely to be alluvial and fluvial sedimentary rock with higher porosity and permeability. This report estimates an order of magnitude potential capacity of approximately 137 billion metric tons for supercritical CO{sub 2}. The pore space within the basins represent hundreds of years of potential storage for supercritical CO{sub 2} and CO{sub 2} stored in aqueous form. There are many sources of CO{sub 2} within the region that could use the trend for geologic storage. Thirty one coal fired power plants are located within 100 miles of the deepest portions of

  17. Structure and Stratigraphy of the Rift Basins in the Northern Gulf of California: Results from Analysis of Seismic Reflection and Borehole Data.

    Science.gov (United States)

    Martín, A.; González, M.; Helenes, J.; García, J.; Aragón, M.; Carreño, A.

    2008-12-01

    The northern Gulf of California contains two parallel, north-south trending rift basin systems separated by a basement-high. The interpretation of several exploration wells, and ~4500 km of seismic reflection data from PEMEX (Mexican national oil company) indicate that the tectonically active basins to the west (Wagner- Consag and Upper Delfin basins) may have initiated synchronously with the now abandoned Tiburón- Tepoca-Altar basins to the east in the Sonora margin. In both basin systems the lower sequence (A) is marine mudstone-siltstone, has parallel reflectors and a largely uniform thickness that reaches up to1.5 km, and gradually pinches out toward the lateral margins. This suggests that the unit was deposited prior to their segmentation by transtensional faulting. Marine microfossils from borehole samples from sequence A in the Tiburón and Consag basins indicates middle Miocene (>11.2 Ma) proto-Gulf conditions. Sequence B conformably overlies sequence A, and is characterized by up to 2 km growth strata with a fanning geometry that show a clear genetic relationship to the major transtensional faults that control the segmentation of the two basin systems. Sequence C in the Tiburón and Tepoca basins is comparatively thin (<800 m) and includes several unconformities, but is much less affected by faulting. In contrast, sequence C in the active Wagner, Consag and Upper Delfin basin is a much thicker (up to 2 km) growth sequence with abundant volcanic intrusions. Marked variations in sequence C in the different basin systems clearly demonstrate a major westward shift of deformation and subsidence at this time. The modern depocenter in Wagner-Consag basins is controlled by the Consag and Wagner faults, which trend parallel to the north ~20 km apart, and show opposite normal offset. These two faults merge at an oblique angle (70°-50°, respectively) into the Cerro Prieto transform fault to the north and likely accommodate an important amount of dextral shear. To

  18. A slow-slipping active fold and thrust system at the SE corner of the Atacama basin, northern Chile

    Science.gov (United States)

    Lin, Y.; Shyu, J. H.; González, G.

    2009-12-01

    The western South American offshore is one of the major active convergent plate boundaries in the world, where the Nazca plate is subducting northeastward beneath the South American plate at a rate of about 84 mm/yr. Despite of this rapid plate convergence, the forearc region of western Andes does not seem to undergo large deformation at present. In order to understand the characteristics and mechanisms of active forearc deformation related to the plate convergence, we investigated tectono-geomorphic features in the area of Tilocalar, near the SE margin of the Atacama Basin in northern Chile, where active structures have been previously identified. To map topographic features produced by active structures, we used a combination of several remote-sensing data sets, including digital elevation models (DEM) made from Shuttle Radar Topographic Mission (SRTM), as well as higher resolution ASTER and QuickBird satellite images. Detailed geomorphic surveys using real time kinematic (RTK) GPS are carried out in the field to obtain high-resolution topographic profiles across these features. We also performed 40Ar/39Ar dating of deformed volcanic rocks in order to determine the long-term slip rates of the active structures. The hyper-aridity of the Atacama Basin results in extremely low erosion and sedimentation rates in the area. As a result, the present relief of land surface is mostly produced by neotectonic activity, and can be used as deformation marker. In the Tilocalar area, several N-S trending ridges are present. These ridges, generally several tens of meters high, are likely formed by asymmetric anticlines or monoclines with steep forelimbs facing east, and these folds are likely fault-propagation folds produced by underlying thrust faults. We suggest that these faults merge at depth to become a major active thrust system. From 40Ar/39Ar plateau ages, we found that the surface ignimbrites mostly deposited in latest Pliocene (2.3~4.3 Ma). If the structures have been

  19. Determining the source and genetic fingerprint of natural gases using noble gas geochemistry: a northern Appalachian Basin case study

    Science.gov (United States)

    Hunt, Andrew G.; Darrah, Thomas H.; Poreda, Robert J.

    2012-01-01

    Silurian and Devonian natural gas reservoirs present within New York state represent an example of unconventional gas accumulations within the northern Appalachian Basin. These unconventional energy resources, previously thought to be noneconomically viable, have come into play following advances in drilling (i.e., horizontal drilling) and extraction (i.e., hydraulic fracturing) capabilities. Therefore, efforts to understand these and other domestic and global natural gas reserves have recently increased. The suspicion of fugitive mass migration issues within current Appalachian production fields has catalyzed the need to develop a greater understanding of the genetic grouping (source) and migrational history of natural gases in this area. We introduce new noble gas data in the context of published hydrocarbon carbon (C1,C2+) (13C) data to explore the genesis of thermogenic gases in the Appalachian Basin. This study includes natural gases from two distinct genetic groups: group 1, Upper Devonian (Marcellus shale and Canadaway Group) gases generated in situ, characterized by early mature (13C[C1  C2][13C113C2]: –9), isotopically light methane, with low (4He) (average, 1  103 cc/cc) elevated 4He/40Ar and 21Ne/40Ar (where the asterisk denotes excess radiogenic or nucleogenic production beyond the atmospheric ratio), and a variable, atmospherically (air-saturated–water) derived noble gas component; and group 2, a migratory natural gas that emanated from Lower Ordovician source rocks (i.e., most likely, Middle Ordovician Trenton or Black River group) that is currently hosted primarily in Lower Silurian sands (i.e., Medina or Clinton group) characterized by isotopically heavy, mature methane (13C[C1 – C2] [13C113C2]: 3), with high (4He) (average, 1.85  103 cc/cc) 4He/40Ar and 21Ne/40Ar near crustal production levels and elevated crustal noble gas content (enriched 4He,21Ne, 40Ar). Because the release of each crustal noble gas (i.e., He, Ne, Ar

  20. Growth Normal Faulting at the Western Edge of the Metropolitan Taipei Basin since the Last Glacial Maximum, Northern Taiwan

    Directory of Open Access Journals (Sweden)

    Chih-Tung Chen

    2010-01-01

    Full Text Available Growth strata analysis is an useful tool in understanding kinematics and the evolution of active faults as well as the close relationship between sedimentation and tectonics. Here we present the Shanchiao Fault as a case study which is an active normal fault responsible for the formation of the 700-m-thick late Quaternary deposits in Taipei Basin at the northern tip of the Taiwan mountain belt. We compiled a sedimentary record, particularly the depositional facies and their dated ages, at three boreholes (SCF-1, SCF-2 and WK-1, from west to east along the Wuku Profile that traverses the Shanchiao Fault at its central segment. By incorporating the global sea level change curve, we find that thickness changes of sediments and changes of depositional environments in the Wuku area are in a good agreement with a rapid sea level rise since the Last Glacial Maximum (LGM of about 23 ka. Combining depositional facies changes and their ages with their thickness, we are able to introduce a simple back-stripping method to reconstruct the evolution of growing strata across the Shanchiao Fault since the LGM. We then estimate the vertical tectonic slip rate since 23 ka, which exhibits 2.2 mm yr-1 between SCF-2 and WK-1 and 1.1 mm yr-1 between SCF-1 and SCF-2. We also obtain the Holocene tectonic subsidence rate of 2.3 mm yr-1 at WK-1 and 0.9 mm yr-1 at SCF-2 since 8.4 ka. We thus conclude that the fault zone consists of a high-angle main fault to the east between SCF-2 and WK-1 and a western lower-angle branch fault between SCF-1 and SCF-2, resembling a tulip structure developed under sinistral transtensional tectonism. We find that a short period of 600-yr time span in 9 - 8.4 ka shows important tectonic subsidence of 7.4 and 3.3 m for the main and branch fault, respectively, consistent with possible earthquake events proposed by previous studies during that time. A correlation between geomorphology and subsurface geology in the Shanchiao Fault zone shows

  1. Ground-water resources and potential hydrologic effects of surface coal mining in the northern Powder River basin, southeastern Montana

    Science.gov (United States)

    Slagle, Steven E.; Lewis, Barney D.; Lee, Roger W.

    1985-01-01

    The shallow ground-water system in the northern Powder River Basin consists of Upper Cretaceous to Holocene aquifers overlying the Bearpaw Shale--namely, the Fox Hills Sandstone; Hell Creek, Fort Union, and Wasatch Formations; terrace deposits; and alluvium. Ground-water flow above the Bearpaw Shale can be divided into two general flow patterns. An upper flow pattern occurs in aquifers at depths of less than about 200 feet and occurs primarily as localized flow controlled by the surface topography. A lower flow pattern occurs in aquifers at depths from about 200 to 1,200 feet and exhibits a more regional flow, which is generally northward toward the Yellowstone River with significant flow toward the Powder and Tongue Rivers. The chemical quality of water in the shallow ground-water system in the study area varies widely, and most of the ground water does not meet standards for dissolved constituents in public drinking water established by the U.S. Environmental Protection Agency. Water from depths less than 200 feet generally is a sodium sulfate type having an average dissolved-solids concentration of 2,100 milligrams per liter. Sodium bicarbonate water having an average dissolved-solids concentration of 1,400 milligrams per liter is typical from aquifers in the shallow ground-water system at depths between 200 and 1,200 feet. Effects of surface coal mining on the water resources in the northern Powder River Basin are dependent on the stratigraphic location of the mine cut. Where the cut lies above the water-yielding zone, the effects will be minimal. Where the mine cut intersects a water-ielding zone, effects on water levels and flow patterns can be significant locally, but water levels and flow patterns will return to approximate premining conditions after mining ceases. Ground water in and near active and former mines may become more mineralized, owing to the placement of spoil material from the reducing zone in the unsaturated zone where the minerals are

  2. Low Angle Normal Fault System Controls the Structure Evolution of Baiyun Deepwater Basin and Its Lithosphere Thinning, Northern South China Sea

    Science.gov (United States)

    Zhao, Y.; Ren, J.; Yang, L.

    2015-12-01

    The discovery of the transition area from ~30 km to weakly thinned continental crust (<12 km) in Baiyun deepwater basin, Northern South China Sea leads to two questions: What controls extreme crustal thinning and what is the nature of Baiyun basin. The 3D seismic data newly acquired show that Baiyun basin is an asymmetric half graben mainly controlled by a set of north-dipping normal faults converging in deep. By employing the principle of back-stripping, we estimate the fault dips and slip amount would be in the absence of post-rift sediments and seawater loading. Results show these Middle Eocene faults were extremely active, with a high accumulation horizontal displacement (> 10 km) and an initial very low angle (<7°), followed by a rotated into sub-horizontal. A general scenario for extension of the uppermost continental crust probably includes simultaneous operation of low angle normal fault (F1) as well as parallel arrays of step-faults (domino-faults, f2-f9). Under such a scenario, it shows no obvious extension discrepancy in Baiyun basin. Our results indicate that Baiyun sag preserves information recording the continent thinning before the seafloor spreading, and it could be an abandoned inner rifted basin.

  3. Meltwater palaeohydrology of the Baker River basin (Chile/Argentina) during Late Pleistocene deglaciation of the Northern Patagonia Icefield

    Science.gov (United States)

    Thorndycraft, Varyl; Bendle, Jacob; Benito, Gerardo; Sancho, Carlos; Palmer, Adrian; Rodríguez, Xavier

    2016-04-01

    The Late Pleistocene deglaciation of the Northern Patagonia Icefield (NPI) was characterised by rapid ice sheet thinning and retreat, and the development of large proglacial lake systems characterised by continental scale drainage reversals. In this region, research has focused primarily on the identification of former ice-limits (e.g. moraine ridges) for geochronological analyses, with little attention given to the meltwater palaeohydrology of major river valleys. The Baker River catchment drains the majority of the eastern ice shed of the NPI, with a basin area of 29,000 km2 that includes the large transboundary lakes of General Carrera/Buenos Aires and Cochrane/Puerreydón. The Baker River valley is aligned north to south, crossing the east-west valleys of the main NPI outflow glaciers, and thus represents an important aspect of regional Late Pleistocene palaeogeography. The Baker River valley therefore has the potential to refine regional models of deglaciation through better understanding of relationships between glacier dynamics, ice dammed lakes and meltwater pathways. Here we present geomorphological mapping from the Atlantic-Pacific drainage divide (over 150 km east of the Cordillera) to the lower Baker valley, in order to reconstruct Late Pleistocene palaeohydrology. We provide new mapping of palaeolake shoreline elevations and evidence for glacial lake outburst flood (GLOF) pathways that require a re-evaluation of the currently accepted palaeogeographic models. For example, the palaeohydrological evidence does not support existing models of a unified Buenos Aires/Puerreydón mega-lake at ca. 400m elevation. We propose a relative chronology of palaeohydrological events that help refine the published moraine chronology derived from cosmogenic nuclide exposure dating. Controls on Late Pleistocene meltwater palaeohydrology of the Baker catchment are discussed, including the interplay of glacial processes and regional tectonics, in particular, dynamic

  4. Scenarios for shale gas development and their related land use impacts in the Baltic Basin, Northern Poland

    International Nuclear Information System (INIS)

    Scenarios for potential shale gas development were modelled for the Baltic Basin in Northern Poland for the period 2015–2030 using the land allocation model EUCS100. The main aims were to assess the associated land use requirements, conflicts with existing land use, and the influence of legislation on the environmental impact. The factors involved in estimating the suitability for placement of shale gas well pads were analysed, as well as the potential land and water requirements to define 2 technology-based scenarios, representing the highest and lowest potential environmental impact. 2 different legislative frameworks (current and restrictive) were also assessed, to give 4 combined scenarios altogether. Land consumption and allocation patterns of well pads varied substantially according to the modelled scenario. Potential landscape fragmentation and conflicts with other land users depended mainly on development rate, well pad density, existing land-use patterns, and geology. Highly complex landscapes presented numerous barriers to drilling activities, restricting the potential development patterns. The land used for shale gas development could represent a significant percentage of overall land take within the shale play. The adoption of appropriate legislation, especially the protection of natural areas and water resources, is therefore essential to minimise the related environmental impact. -- Highlights: •A range of scenarios for shale gas development in Poland were modelled. •The impact in terms of land take and competition for land was assessed. •Of land used for industrial purposes, 7–12% was attributed to shale gas extraction. •If unregulated, 24% of well pads were developed within protected areas. •The legislative framework can have a major influence on overall environmental impact

  5. Natural resources and their prospects in the closed basins of rift valley marginal grabens in northern Ethiopia

    Science.gov (United States)

    Meaza, Hailemariam; Frankl, Amaury; Poesen, Jean; Zenebe, Amanuel; Deckers, Jozef; Vaneetvelde, Veerle; Lanckriet, Sil; Nyssen, Jan

    2016-04-01

    With increasing population, producing more food and fibers has led to an expansion of the area under cultivation. For this, much attention is given to low-lying flat areas in search of suitable agricultural lands. The objectives of this paper are therefore: (1) to review the opportunities and challenges of natural resources in the marginal grabens for rural development; (2) to highlight the knowledge gaps and priorities in research and development in the marginal grabens, and (3) to supplement the literature review through repeat transect walks, focus group discussions and interviews across the western rift valley of northern Ethiopia. The paper shows that marginal grabens along the rift valleys are rich both in blue and green water resources due to their topographical and geological characteristics. Spate irrigation has been a growing water management practice to respond to soil moisture deficit. Besides, marginal grabens are fertile plains as a result of alluvial deposition that could be suitable for agricultural development. However, rainfall variability and groundwater withdrawal lead to graben basin closure and salinization. Notably, riverbed incisions and sediment deposition affects drainage systems and water supply in the marginal grabens. As a result, socioeconomic and natural capital of the marginal graben farmers are continuously threatened. Thus, the benefits of natural resources for rural development in the marginal grabens along the rift valley can be optimized if the current bottlenecks are converted into opportunities. A better understanding of the complex marginal graben system via a robust land evaluation framework will improve livelihoods of the communities that live in the (closed) marginal grabens. Keywords: population pressure, marginal grabens, endorheic lakes, salinization, Ethiopia

  6. Sedimentological Characteristics and Geochemistry of Ajali Sandstone Exposed at Ofe-Jiji and Environs, Northern Anambra Basin, Nigeria

    Directory of Open Access Journals (Sweden)

    Y.B. Gideon

    2014-01-01

    Full Text Available Textural, mineralogical and structural studies as well as outcrop mapping of sandstone in Ofe-Jiji and environs were carried out in order to interpret depositional environment of Ajali sandstone exposed at Ofe-Jiji and environs of the northern Anambra Basin. The sandstone is false bedded, medium-coarse grained (average of 1.13 mm in diameter, poorly sorted and strongly coarsely skewed with an average skewness value of -0.72. Chemical analysis indicates that the sandstone exhibits average SiO2 contents ranging from 59.12 to 60.20% with an average value of 59.80% while alumina (Al2O3 content range between 2.51 and 2.75% with an average of 2.63%. The mineralogical composition shows on the average 56.98 quartz, 6.30 feldspar, 31.78% rock fragment and 4.93% matrix and cement. The major framework composition is Q56 F6 L36 which classifies the sandstone as lithic arenite. The sub angular texture and the geochemical assay of 22.74 ratios (SiO2/Al2O3 and 3.36 ratios (Na2O/K2O indicate low chemically stable minerals in the sandstone and depict mineralogical immaturity. Also, the average ZTR% index of 52.36% with Tourmaline as the least abundant of ultra-stable minerals indicates sub-mature to immature mineralogy of the sandstone. The sandstone may be described as Fe-Sandstone based on Herron Classification Scheme. The dominance of Fe2O3 (26.57% in the sandstone renders it ferruginous and reflects oxidizing environment. Ophiomorpha burrow in the upper unit of the beds strongly suggests fluvial origin.

  7. Formation of hydrothermal deposits at Kings Triple Junction, northern Lau back-arc basin, SW Pacific: The geochemical perspectives

    Science.gov (United States)

    Paropkari, Anil L.; Ray, Durbar; Balaram, V.; Surya Prakash, L.; Mirza, Imran H.; Satyanarayana, M.; Gnaneshwar Rao, T.; Kaisary, Sujata

    2010-04-01

    An inactive hydrothermal field was discovered near Kings Triple Junction (KTJ) in northern Lau back-arc basin during 19th cruise of R/V Akademik Mstislav Keldysh in 1990. The field consisted of a large elongated basal platform 'the pedestal' with several 'small' chimneys on its periphery and one 'main mound' superposed over it. The surrounding region is carpeted with lava pillows having ferromanganese 'precipitate' as infillings. The adjoining second field consisted of small chimney like growths termed as 'Christmas Tree' Field. The basal pedestal, the peripheral chimneys and small 'Christmas Tree' like growths (samples collected by MIR submersibles), though parts of the same hydrothermal field, differ significantly in their mineralogy and elemental composition indicating different history of formation. The pedestal slab consisting of chalcopyrite and pyrite as major minerals and rich in Cu is likely to have formed at higher temperatures than sphalerite dominated peripheral chimney. Extremely low concentration of high field strength elements (e.g. Zr, Hf, Nb and Ta) and enrichment of light REE in these sulfides indicate prominent influence of aqueous arc-magma, rich in subduction components. The oxide growths in the 'Christmas Tree' Field have two distinct layers, Fe rich orange-red basal part which seems to have formed at very low temperature as precipitates from diffused hydrothermal flows from the seafloor whereas Mn rich black surface coating is formed from hydrothermal fluids emanated from the seafloor during another episode of hydrothermal activity. Perhaps this is for the first time such unique hydrothermal oxide growths are being reported in association with hydrothermal system. Here, we discuss the possible processes responsible for the formation of these different hydrothermal deposits based on their mineralogy and geochemistry.

  8. Innovative Methodology for Detection of Fracture-Controlled Sweet Spots in the Northern Appalachian Basin

    Energy Technology Data Exchange (ETDEWEB)

    Robert Jacobi; John Fountain; Stuart Loewenstein; Edward DeRidder; Bruce Hart

    2007-03-31

    For two consecutive years, 2004 and 2005, the largest natural gas well (in terms of gas flow/day) drilled onshore USA targeted the Ordovician Trenton/Black River (T/BR) play in the Appalachian Basin of New York State (NYS). Yet, little data were available concerning the characteristics of the play, or how to recognize and track T/BR prospects across the region. Traditional exploration techniques for entry into a hot play were of limited use here, since existing deep well logs and public domain seismic were almost non-existent. To help mitigate this problem, this research project was conceived with two objectives: (1) to demonstrate that integrative traditional and innovative techniques could be used as a cost-effective reconnaissance exploration methodology in this, and other, areas where existing data in targeted fracture-play horizons are almost non-existent, and (2) determine critical characteristics of the T/BR fields. The research region between Seneca and Cayuga lakes (in the Finger Lakes of NYS) is on strike and east of the discovery fields, and the southern boundary of the field area is about 8 km north of more recently discovered T/BR fields. Phase I, completed in 2004, consisted of integrating detailed outcrop fracture analyses with detailed soil gas analyses, lineaments, stratigraphy, seismic reflection data, well log data, and aeromagnetics. In the Seneca Lake region, Landsat lineaments (EarthSat, 1997) were coincident with fracture intensification domains (FIDs) and minor faults observed in outcrop and inferred from stratigraphy. Soil gas anomalies corresponded to ENE-trending lineaments and FIDs. N- and ENE-trending lineaments were parallel to aeromagnetic anomalies, whereas E-trending lineaments crossed aeromagnetic trends. 2-D seismic reflection data confirmed that the E-trending lineaments and FIDs occur where shallow level Alleghanian salt-cored thrust-faulted anticlines occur. In contrast, the ENE-trending FIDs and lineaments occur where Iapetan

  9. Innovative Methodology for Detection of Fracture-Controlled Sweet Spots in the Northern Appalachian Basin

    Energy Technology Data Exchange (ETDEWEB)

    Robert Jacobi; John Fountain; Stuart Loewenstein; Edward DeRidder; Bruce Hart

    2007-03-31

    For two consecutive years, 2004 and 2005, the largest natural gas well (in terms of gas flow/day) drilled onshore USA targeted the Ordovician Trenton/Black River (T/BR) play in the Appalachian Basin of New York State (NYS). Yet, little data were available concerning the characteristics of the play, or how to recognize and track T/BR prospects across the region. Traditional exploration techniques for entry into a hot play were of limited use here, since existing deep well logs and public domain seismic were almost non-existent. To help mitigate this problem, this research project was conceived with two objectives: (1) to demonstrate that integrative traditional and innovative techniques could be used as a cost-effective reconnaissance exploration methodology in this, and other, areas where existing data in targeted fracture-play horizons are almost non-existent, and (2) determine critical characteristics of the T/BR fields. The research region between Seneca and Cayuga lakes (in the Finger Lakes of NYS) is on strike and east of the discovery fields, and the southern boundary of the field area is about 8 km north of more recently discovered T/BR fields. Phase I, completed in 2004, consisted of integrating detailed outcrop fracture analyses with detailed soil gas analyses, lineaments, stratigraphy, seismic reflection data, well log data, and aeromagnetics. In the Seneca Lake region, Landsat lineaments (EarthSat, 1997) were coincident with fracture intensification domains (FIDs) and minor faults observed in outcrop and inferred from stratigraphy. Soil gas anomalies corresponded to ENE-trending lineaments and FIDs. N- and ENE-trending lineaments were parallel to aeromagnetic anomalies, whereas E-trending lineaments crossed aeromagnetic trends. 2-D seismic reflection data confirmed that the E-trending lineaments and FIDs occur where shallow level Alleghanian salt-cored thrust-faulted anticlines occur. In contrast, the ENE-trending FIDs and lineaments occur where Iapetan

  10. Zircon Hf isotopic constraints on the mantle source of felsic magmatic rocks in the Phan Si Pan uplift and Tu Le basin, northern Vietnam

    Science.gov (United States)

    Usuki, T.; Lan, C.; Tran, T.; Pham, T.; Wang, K.

    2013-12-01

    Permian plume-related rocks, such as picrites, flood basalts and silicic volcanic rocks occur in northern Vietnam. This area was displaced 600 km southeastward along the Ailao Shan-Red River fault during mid-Tertiary in response to the India-Eurasia collision. The original location of the area was situated at the central Emeishan Large Igneous Province (ELIP) in SW China before Tertiary. The picrites and flood basalts in northern Vietnam have been investigated by many authors and are comparable with the ELIP. While, felsic magmatisms in northern Vietnam has been poorly studied. Zircon U-Pb age and Hf isotopic data are useful to compare the felsic magmatism in northern Vietnam with that in the ELIP, because the magmatisms of the ELIP had a characteristic time period (260-250 Ma) and the Hf isotopes show a remarkable mantle signature. Therefore, this study carried out in-situ U-Pb ages and Hf isotopic compositions for 300 zircon grains in eighteen granitoids and rhyolites in Phan Si Pan uplift and Tu Le basin in northern Vietnam. Zircons from the granitoids and rhyolites occasionally show development of {101} pyramid and {100} prism crystal facies, suggesting typical zircons crystallized from high temperature alkaline granite. 206Pb/238U ages of granitoid and rhyolite yield consistently in a narrow range of 260 to 250 Ma, which coincides with those from peralkaline to metaluminous granites in the ELIP. ɛHf(t) values of zircons in rhyolites and granites of this study dominate in the range of +5 to +10, which is consistent with those from the ELIP. U-Pb ages and Hf isotopic compositions of zircons indicate that felsic magmatic rocks in the Phan Si Pan uplift and Tu La basin have been derived from the same mantle source with the ELIP.

  11. Eocene to late Oligocene history of crustal shortening within the Hoh Xil Basin and implications for the uplift history of the northern Tibetan Plateau

    Science.gov (United States)

    Staisch, Lydia M.; Niemi, Nathan A.; Clark, Marin K.; Chang, Hong

    2016-04-01

    The timing and magnitude of deformation across the northern Tibetan Plateau are poorly constrained but feature prominently in geodynamic models of the plateau's evolution. The Fenghuoshan fold and thrust belt, located in the Hoh Xil Basin, provides a valuable record of the Cenozoic deformation history of the northern Tibetan Plateau. Here we integrate fault gouge geochronology, low-temperature thermochronology, geologic mapping, and a balanced cross section to resolve the deformation history of Hoh Xil Basin. Chronologic data suggest that deformation initiated in the mid-Eocene continued until at least 34 Ma and ceased by 27 Ma. The balanced cross section resolves 34 ± 12 km upper crustal shortening (24 ± 9%). We explore whether the observed Cenozoic shortening can account for the modern elevation and lithospheric thickness in the northern Tibetan Plateau. For a range of reasonable preshortening conditions, we conclude that the observed shortening alone cannot achieve modern crustal and mantle lithospheric thicknesses or modern elevation without either the removal of lithospheric mantle, the influx of lower crustal material, or some combination of these processes. Our results, along with previous studies, suggest that crustal shortening propagated into the northern Tibetan Plateau shortly after the onset of the Indo-Asian collision. The small magnitude of shortening and the late Oligocene cessation of deformation in the northern Tibetan Plateau raise questions of how and where the remaining Indo-Asian convergence was accommodated between Eocene to mid-Miocene time, prior to the approximately late Miocene establishment of the deformation patterns observed in the present day.

  12. Middle-Upper Ordovician (Darriwilian-Early Katian) Positive Carbon Isotope Excursions in the Northern Tarim Basin, Northwest China:Implications for Stratigraphic Correlation and Paleoclimate

    Institute of Scientific and Technical Information of China (English)

    Cunge Liu; Guorong Li; Dawei Wang; Yongli Liu; Mingxia Luo; Xiaoming Shao

    2016-01-01

    ABSTRACT:Three positive carbon isotope excursions are reported from Middle–Upper Ordovician in Tahe oil-gas field, northern Tarim Basin. Based on conodont biostratigraphy, the Middle Darriwilian Isotope Carbon Excursion (MDICE) and the Guttenberg Carbon Isotope Excursion (GICE) are identified from Darriwilian to Early Katian by the aid of whole-rock carbon isotope data from two well cores. Positive excursion within conodont Pygodus anserinus zone is developed in Early Sandbian, and the fluctuation range is no less than MDICE. Because the range of this excursion in the generalized global carbon isotope curve is short, previous studies paid little attention to it, and named Early Sandbian Isotope Carbon Excursion (ESICE) in this paper. Furthermore, these positive excursions are not directly related to sea level fluctuations and the MDICE and GICE identified in northern Tarim can be globally correlated to that in southern China, North America, South America, and Europe. The Saergan Fm. source rocks of Middle-Upper Ordovician in Kalpin Dawangou outcrop are in accord with the geologic time of MDICE and ESICE, and GICE have strong ties to the source rock of Lianglitag Fm. in basin. Abundant organic carbon burial is an important factor in genesis of positive isotope carbon excursions. Positive oxygen isotope excursion, conodont fauna turnover, decreased conodont total diversity, and the change of sedimentary facies indicated that dramatic changes of paleoceanographic environment of Early-Middle Ordovician in Tarim Basin started from the end of Darriwillian, and an obvious icehouse climate of Late Ordovician occurred in ESICE.

  13. Identifying key climate and environmental factors affecting rates of post-fire big sagebrush (Artemisia tridentata) recovery in the northern Columbia Basin, USA

    Science.gov (United States)

    Shinneman, Douglas; McIlroy, Susan

    2016-01-01

    Sagebrush steppe of North America is considered highly imperilled, in part owing to increased fire frequency. Sagebrush ecosystems support numerous species, and it is important to understand those factors that affect rates of post-fire sagebrush recovery. We explored recovery of Wyoming big sagebrush (Artemisia tridentata ssp.wyomingensis) and basin big sagebrush (A. tridentata ssp. tridentata) communities following fire in the northern Columbia Basin (Washington, USA). We sampled plots across 16 fires that burned in big sagebrush communities from 5 to 28 years ago, and also sampled nearby unburned locations. Mixed-effects models demonstrated that density of large–mature big sagebrush plants and percentage cover of big sagebrush were higher with time since fire and in plots with more precipitation during the winter immediately following fire, but were lower when precipitation the next winter was higher than average, especially on soils with higher available water supply, and with greater post-fire mortality of mature big sagebrush plants. Bunchgrass cover 5 to 28 years after fire was predicted to be lower with higher cover of both shrubs and non-native herbaceous species, and only slightly higher with time. Post-fire recovery of big sagebrush in the northern Columbia Basin is a slow process that may require several decades on average, but faster recovery rates may occur under specific site and climate conditions.

  14. Geometry of the El Fresnal basin, northern Chihuahua, Mexico, as inferred from three-dimensional gravity modeling (parte A)

    OpenAIRE

    W. L. Bandy; J. Ortega Ramírez; J. M. Maillol; A. Valiente Banuet; Rodríguez, J. A.

    2002-01-01

    A multidisciplinary study of the El Fresnal basin, Chihuahua, Mexico is being conducted to investigate the relationships between the structure, vegetation and geomorphology and the Quaternary paleoenvironment. As part of this study, 221 new gravity measurements were collected within the basin and combined with 506 preexisting measurements from the surrounding area to determine the basin geometry and the depth of the sediment infill. A basement-depth model calculated from these data indicates ...

  15. Pockmark development in the Petrel Sub-basin, Timor Sea, Northern Australia: Seabed habitat mapping in support of CO2 storage assessments

    Science.gov (United States)

    Nicholas, W. A.; Nichol, S. L.; Howard, F. J. F.; Picard, K.; Dulfer, H.; Radke, L. C.; Carroll, A. G.; Tran, M.; Siwabessy, P. J. W.

    2014-07-01

    The extent to which fluids may leak from sedimentary basins to the seabed is a critical issue for assessing the potential of a basin for carbon capture and storage. The Petrel Sub-basin, located beneath central and eastern Joseph Bonaparte Gulf in tropical northern Australia, was identified as potentially suitable for the geological storage of CO2 because of its geological characteristics and proximity to offshore gas and petroleum resources. In May 2012, a multidisciplinary marine survey (SOL5463) was undertaken to collect data in two targeted areas of the Petrel Sub-basin to facilitate an assessment of its CO2 storage potential. This paper focuses on Area 1 of that survey, a 471 km2 area of sediment-starved shelf (water depths of 78 to 102 m), characterised by low-gradient plains, low-lying ridges, palaeo-channels and shallow pockmarks. Three pockmark types are recognised: small shallow unit pockmarks 10-20 m in diameter (generally mangrove deposits and shells to have begun after 15.5 cal ka BP when a rapid marine transgression of Bonaparte Shelf associated with meltwater pulse 1A drowned coastal mangrove environments. Pockmark development is likely an ongoing process driven by fluid seepage at the seabed, and sourced from CO2 produced in the shallow sub-surface (<2 m) sediment. No evidence for direct connection to deeper features was observed.

  16. Application of the authigenic 10Be/9Be dating method to Late Miocene-Pliocene sequences in the northern Danube Basin (Pannonian Basin System): Confirmation of heterochronous evolution of sedimentary environments

    Science.gov (United States)

    Šujan, Michal; Braucher, Régis; Kováč, Michal; Bourlès, Didier L.; Rybár, Samuel; Guillou, Valéry; Hudáčková, Natália

    2016-02-01

    Authigenic 10Be/9Be dating method was applied to lacustrine, deltaic and alluvial sequences of the northern Danube Basin (Pannonian Basin System), to bridge the insufficiency of geochronological data for the Late Miocene to Pliocene period. The measurements of 51 samples (both lacustrine and floodplain), ranging from 11.6 to 0.95 Ma are consistent with the existing magnetostratigraphic and biostratigraphic data standing mainly on the evolution degree of endemic mollusk fauna, mammals and dinocysts. This agreement confirms our assumption that the incoming beryllium fluxes remained constant over the studied time period and thus that the two initial 10Be/9Be ratios determined in actual Holocene/Late Pleistocene sediments (lacustrine and floodplain) are valid for these environments. The obtained ages indicate gradual progradation of the deltaic depositional systems across the Danube Basin with a clear time-transgressional character, replacing basin floor and shelfal environments. Deltaic sedimentation occurred firstly in the north at foothills of the Western Carpathians from 11.0 Ma, and changed to the alluvial environment after 10.5 Ma. At the same time (~ 10.5 Ma), the paleo-Danube deltaic system draining the Eastern Alps entered the study area from the Vienna Basin situated on the West. Later, the deltaic systems were merged in the central part of the basin and reached its southeastern margin at ~ 9.4 Ma. Regression of the Lake Pannon from the southernmost part of the study area is evidenced after 8.7 Ma. Alluvial deposition of meandering rivers lasting until 6.0-5.0 Ma followed and was interrupted by the early Pliocene basin inversion. Sedimentation of braided streams took place during the late Pliocene and Pleistocene, reflecting uplift of mountains surrounding the basin margins. This study documents the powerful potential of the authigenic 10Be/9Be dating method and its reliability in a basin with complicated tectonic and sedimentary history. It demonstrates that

  17. Miocene Bahean stratigraphy in the Longzhong Basin,northern central China and its implications in environmental change

    Institute of Scientific and Technical Information of China (English)

    LI; Jijun; ZHANG; Jun; SONG; Chunhui; ZHAO; Zhijun; ZHANG; Yong; WANG; Xiuxi; ZHANG; Jianming; CUI; Qiaoyu

    2006-01-01

    Fossil mammal-riched Neogene strata are widely distributed in the southeast corner of the huge Longzhong Basin at Tianshui,Gansu Province,northern central China.Hipparion weihoense,a typical member of late Middle Miocene Bahean stage,was recently excavated at Yaodian along a well-exposed outcrop.Owing to the importance of the Bahean stage in the mammalian evolution and its potential for environmental change,we suggested a name of Yaodian Formation for the stratigraphy,which is correlated to the Bahe Formation at Lantian,Shaanxi.High resolution paleomagnetic dating of the section shows that the Yaodian Formation covers the period between 11.67 Ma and 7.43 Ma,with the site bearing Hipparion weihoense being estimated at about 10.54-10.30 Ma,providing first magnetostratigraphic chronology for the Bahean Stage.The Yaodian Formation consists of fluvial channel deposits (11.67-10.40 Ma) at the bottom,floodplain deposits in the middle (10.40-9.23 Ma) and shallow lake sediments at the top (9.23-7.43 Ma).This upward fining sequence suggests that the relief in nearby mountain ranges such as West Qinling to the south and Huajia Ling to the north was greatly reduced after long-term denudation,fluvial transport capacity was low,and finally the drainage system was disintegrated,replaced with broad-shallow lakes in which only fine sediments like mud and marlite were deposited,indicating an old stage of development of a planation surface.A remarkable shift in ecology and climatic environment was found at 7.4-7.7 Ma when paleoclimate changed from early warm humid to late dry as indicated by sedimentary facies changed from early shallow lake sequence to late eolian red clays and a former coniferous-deciduous mixed forest was replaced by grassland,leading to great growth of Hipparion Fauna of Baodean stage in the region.Therefore,it is estimated that the present high relief of Qinling and drainage pattern did not come into being until Late Pliocene in response to intensive

  18. Genesis of Middle Miocene Yellowstone hotspot-related bonanza epithermal Au-Ag deposits, Northern Great Basin, USA

    Science.gov (United States)

    Saunders, J. A.; Unger, D. L.; Kamenov, G. D.; Fayek, M.; Hames, W. E.; Utterback, W. C.

    2008-09-01

    Epithermal deposits with bonanza Au-Ag veins in the northern Great Basin (NGB) are spatially and temporally associated with Middle Miocene bimodal volcanism that was related to a mantle plume that has now migrated to the Yellowstone National Park area. The Au-Ag deposits formed between 16.5 and 14 Ma, but exhibit different mineralogical compositions, the latter due to the nature of the country rocks hosting the deposits. Where host rocks were primarily of meta-sedimentary or granitic origin, adularia-rich gold mineralization formed. Where glassy rhyolitic country rocks host veins, colloidal silica textures and precious metal-colloid aggregation textures resulted. Where basalts are the country rocks, clay-rich mineralization (with silica minerals, adularia, and carbonate) developed. Oxygen isotope data from quartz (originally amorphous silica and gels) from super-high-grade banded ores from the Sleeper deposit show that ore-forming solutions had δ 18O values up to 10‰ heavier than mid-Miocene meteoric water. The geochemical signature of the ores (including their Se-rich nature) is interpreted here to reflect a mantle source for the “epithermal suite” elements (Au, Ag, Se, Te, As, Sb, Hg) and that signature is preserved to shallow crustal levels because of the similar volatility and aqueous geochemical behavior of the “epithermal suite” elements. A mantle source for the gold in the deposits is further supported by the Pb isotopic signature of the gold ores. Apparently the host rocks control the mineralization style and gangue mineralogy of ores. However, all deposits are considered to have derived precious metals and metalloids from mafic magmas related to the initial emergence of the Yellowstone hotspot. Basalt-derived volatiles and metal(loid)s are inferred to have been absorbed by meteoric-water-dominated geothermal systems heated by shallow rhyolitic magma chambers. Episodic discharge of volatiles and metal(loid)s from deep basaltic magmas mixed with

  19. Algas marinas bentónicas de la costa noroccidental de Guerrero, México Benthic marine algae of the west coast of Guerrero, Mexico

    Directory of Open Access Journals (Sweden)

    Luz Elena Mateo-Cid

    2012-12-01

    Full Text Available Se presentan los resultados de un estudio sobre algas marinas bentónicas en 7 localidades de la costa noroccidental de Guerrero, México. Se determinó la presencia de 163 especies de algas marinas. Se identificaron 17 especies de Cyanobacteria, 93 Rhodophyta, 28 Chlorophyta y 25 de Heterokontophyta. Se citan 54 registros nuevos para el litoral de Guerrero, 2 también nuevos, Myrionema strangulans Greville y Acrochaete ramosa (N.L.Gardner O'Kelly para la costa del Pacífico. Cada especie se acompaña de datos sobre su distribución en el área de estudio, su estado reproductivo, nivel de marea, hábitat, observaciones, epifitismo y número de herbario o de recolección. Se comparó la riqueza específica entre la estación climática de lluvias y la de secas. La división Rhodophyta dominó en términos de diversidad en relación con las 3 divisiones restantes. La ficoflora de la costa noroccidental de Guerrero es de afinidad tropical y más diversa en la época de secas.We present results on the study on benthic marine algae in 7 localities from the west coast of Guerrero, Mexico. We report 163 species: 17 Cyanobacteria, 93 Rhodophyta, 28 Chlorophyta and 25 Heterokontophyta. Fifty four are new records for Guerrero; while Myrionema strangulans Greville and Acrochaete ramosa (N.L.Gardner O'Kelly are new to the Pacific coast of Mexico. Each species includes data on its distribution, reproductive stages, tidal level, facies, epiphytism and herbarium's number. Species diversity was compared for 2 different climatic seasons. The Rhodophyta are dominant in terms of diversity in relation to the other groups. The algal flora of the northwest coast of Guerrero is tropical and the greatest diversity was found during dry seasons.

  20. Modeling annual discharge of six Mexico’s northern rivers

    Directory of Open Access Journals (Sweden)

    Jose de Jesus Navar

    2012-04-01

    Full Text Available The overall goal of this report was to understand river discharge variability to improve conventional water management practices of Mexico’s northern subtropical rivers. This report addresses whether: a river discharge tendencies, patterns and cycles can be detected with proxy and instrumental records; and b annual discharge can be forecasted by stochastic models. Eleven gauging stations of six major rivers; three lowland rivers discharging into the Pacific Ocean (Rios Santa Cruz, Acaponeta, and San Pedro; five upland rivers draining into the Pacific Ocean (Rio San Pedro: Peña del Aguila, Refugio Salcido, San Felipe, Vicente Guerrero and Saltito, one river flowing across the interior Basin (Rio Nazas: Salomé Acosta and two more rivers discharging into the Northern Gulf of Mexico (Rio San Juan: El Cuchillo and Rio Ramos: Pablillos were statistically analyzed. Instrumental recorded daily discharge data (1940-1999 and reconstructed time series data (1860-1940 using dendrochronological analysis delivered annual discharge data to be modeled using autoregressive integrated moving average, ARIMA models. Spectral density analysis, autocorrelation functions and the standardized annual discharge data evaluated annual discharge frequency cycles. Results showed ARIMA models with two autoregressive and one moving average coefficient adequately project river discharge for all gauging stations with four of them showing significant declining patterns since 1860. ARIMA models in combination with autocorrelation and spectral density techniques as well as standardized departures, in agreement with present (2002-2010 observations, forecast a wet episode that may last between 9 and 12 years thereafter entering again into a dry episode. Three dry-wet spell cycles with different time scales (1-2 years; 4-7 years; 9-12 years could be discerned from these analyses that are consistent for all three northern Mexico’s river clusters that emerged from a multivariate

  1. Report on the Predation Index, Predator Control Fisheries, and Program Evaluation for the Columbia River Basin Experimental Northern Pikeminnow Management Program, 2008 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Porter, Russell [Pacific States Marine Fisheries Commission].

    2009-09-10

    This report presents results for year seventeen in the basin-wide Experimental Northern Pikeminnow Management Program to harvest northern pikeminnow1 (Ptychocheilus oregonensis) in the Columbia and Snake Rivers. This program was started in an effort to reduce predation by northern pikeminnow on juvenile salmonids during their emigration from natal streams to the ocean. Earlier work in the Columbia River Basin suggested predation by northern pikeminnow on juvenile salmonids might account for most of the 10-20% mortality juvenile salmonids experience in each of eight Columbia River and Snake River reservoirs. Modeling simulations based on work in John Day Reservoir from 1982 through 1988 indicated that, if predator-size northern pikeminnow were exploited at a 10-20% rate, the resulting restructuring of their population could reduce their predation on juvenile salmonids by 50%. To test this hypothesis, we implemented a sport-reward angling fishery and a commercial longline fishery in the John Day Pool in 1990. We also conducted an angling fishery in areas inaccessible to the public at four dams on the mainstem Columbia River and at Ice Harbor Dam on the Snake River. Based on the success of these limited efforts, we implemented three test fisheries on a system-wide scale in 1991 - a tribal longline fishery above Bonneville Dam, a sport-reward fishery, and a dam-angling fishery. Low catch of target fish and high cost of implementation resulted in discontinuation of the tribal longline fishery. However, the sport-reward and dam-angling fisheries were continued in 1992 and 1993. In 1992, we investigated the feasibility of implementing a commercial longline fishery in the Columbia River below Bonneville Dam and found that implementation of this fishery was also infeasible. Estimates of combined annual exploitation rates resulting from the sport-reward and dam-angling fisheries remained at the low end of our target range of 10-20%. This suggested the need for additional

  2. Tectono-sedimentary evolution of an extensional basin revealed by a combined photo-geological and field-mapping approach. The Montefalco Basin (Northern Apennines, Italy)

    Science.gov (United States)

    Bucci, Francesco; Mirabella, Francesco; Santangelo, Michele; Cardinali, Mauro; Guzzetti, Fausto

    2016-04-01

    Active extensional basins are important since their sedimentary infills and bounding tectonic structures provide: i) sinks with preservation potential for sedimentary and fossil records of past changes in climate and sediment/water supply, ii) information on the growth, activity, decay and death of normal faults, iii) vast economic reserves of hydrocarbons, water and minerals. Unfortunately, quaternary extensional basins, especially if located in humid and temperate climate environments, are often characterized by extensively cultivated areas, homogeneous terrains and quite flat morphologies. Furthermore, they commonly host human settlements, together with roads, economic and industrial infrastructures, with a consequent limited availability of good outcrops. Such a limitation can (often severely) hamper an adequate mapping of the sedimentary infill. Therefore alternative methodological approaches (such as aerial photographs interpretation, API) are needed to integrate heterogeneous and incomplete datasets. This contribution presents an updated photo-geological map of a Quaternary extensional basin in Central Italy, the Montefalco Basin. This basin developed in a continental environment characterized by clayey-sandy lacustrine and fluvial sequences (late Pliocene - early Pleistocene) underlying more recent coarse grained deposits related to alluvial fan environment (early-to-late Pleistocene) and younger palustrine deposits (late Pleistocene). Since the late Pleistocene, regional uplift and local tectonics led to the end of deposition in the Montefalco basin, which experienced a diffuse incision and the modification of the drainage network, in response to the W-to-E migration of active faulting and tectonic subsidence. The new photo-geological map represents an important improvement compared to the existing data, since it provides unprecedented and spatially distributed information on the geometry of the continental deposits and on the tectonic structures affecting

  3. Late Mesozoic to Paleogene stratigraphy of the Salar de Atacama Basin, Antofagasta, Northern Chile: Implications for the tectonic evolution of the Central Andes

    Science.gov (United States)

    Mpodozis, Constantino; Arriagada, César; Basso, Matilde; Roperch, Pierrick; Cobbold, Peter; Reich, Martin

    2005-04-01

    The Salar de Atacama basin, the largest "pre-Andean" basin in Northern Chile, was formed in the early Late Cretaceous as a consequence of the tectonic closure and inversion of the Jurassic-Early Cretaceous Tarapacá back arc basin. Inversion led to uplift of the Cordillera de Domeyko (CD), a thick-skinned basement range bounded by a system of reverse faults and blind thrusts with alternating vergence along strike. The almost 6000-m-thick, upper Cretaceous to lower Paleocene sequences (Purilactis Group) infilling the Salar de Atacama basin reflects rapid local subsidence to the east of the CD. Its oldest outcropping unit (Tonel Formation) comprises more than 1000 m of continental red sandstones and evaporites, which began to accumulate as syntectonic growth strata during the initial stages of CD uplift. Tonel strata are capped by almost 3000 m of sandstones and conglomerates of western provenance, representing the sedimentary response to renewed pulses of tectonic shortening, which were deposited in alluvial fan, fluvial and eolian settings together with minor lacustrine mudstone (Purilactis Formation). These are covered by 500 m of coarse, proximal alluvial fan conglomerates (Barros Arana Formation). The top of the Purilactis Group consists of Maastrichtian-Danian alkaline lava and minor welded tuffs and red beds (Cerro Totola Formation: 70-64 Ma K/Ar) deposited during an interval of tectonic quiescence when the El Molino-Yacoraite Late Cretaceous sea covered large tracts of the nearby Altiplano-Puna domain. Limestones interbedded with the Totola volcanics indicate that this marine incursion advanced westwards to reach the eastern CD slope. CD shortening in the Late Cretaceous was accompanied by volcanism and continental sedimentation in fault bounded basins associated to strike slip along the north Chilean magmatic arc to the west of the CD domain, indicating that oblique plate convergence prevailed during the Late Cretaceous. Oblique convergence seems to have

  4. Tanaidáceos (Crustacea: Peracarida de los litorales de Guerrero y Oaxaca, México Littoral tanaidaceans (Crustacea: Peracarida from Guerrero and Oaxaca, Mexico

    Directory of Open Access Journals (Sweden)

    Jani Jarquín-González

    2010-10-01

    Full Text Available Los tanaidáceos son componentes esenciales de las cadenas tróficas del bentos marino, son fuente de alimento para especies de relevancia comercial y para otros organismos marinos. A pesar de su importancia, el conocimiento del grupo se ha rezagado debido a los problemas relacionados con su biología y taxonomía, y por la carencia de muestreos exhaustivos y sistemáticos; así, en las costas de Guerrero y Oaxaca sólo se había registrado 1 género. Por lo anterior, el objetivo fue conocer la composición específica y los patrones de distribución de los tanaidáceos litorales de Guerrero y Oaxaca. De 4 275 ejemplares, se identificaron 6 familias y 9 morfotipos: Hexapleomera robusta, Sinelobus stanfordi, Leptochelia cf. dubia, Paratanais cf. denticulatus, Paradoxapseudes cf. garthi, Apseudormorpha sp., Cyclopoapseudes cf. indecorus, Synapseudes sp. y Parapseudes pedispinis. Todos son registros nuevos para el litoral de Guerrero y Oaxaca. Se amplía el intervalo de distribución hacia el norte, para H. robusta de islas Galápagos a Guerrero. Para S. stanfordi y P. pedispinis se proporcionan localidades intermedias que rompen con la distribución disyunta previa en el Pacífico oriental. Hay 6 especies, posiblemente nuevas, con distribución restringida; 2 son de amplia distribución y 1 restringida al Pacífico oriental tropical.The tanaidaceans are essential components in food chains of marine benthos, since they are the main food source for commercially important species and other marine organisms. Despite their importance, problems related to their biology and taxonomy have delayed the understanding of the group, as observed on the coasts of Guerrero and Oaxaca, where only 1 genus was previously known. The aim was to determine the species richness and distribution patterns of littoral tanaids from Guerrero and Oaxaca. A total of 4 275 specimens were collected and 6 families and 9 morphotypes have been identified: Hexapleomera robusta

  5. Eolic central Guerrero Negro, BCS, Mexico, performance first year operation; Central eolica Guerrero Negro, BCS, Mexico, resultados del primer ano de operacion

    Energy Technology Data Exchange (ETDEWEB)

    Cadenas Tovar, Roberto; Sanchez Cornejo, Carlos; Lopez Rios, Serafin [Comision Federal de Electricidad, Morelia, Michoacan (Mexico); Ley Romero, Jose R [Comision Federal de Electricidad, Guerrero Negro, Baja California Sur (Mexico)

    2000-07-01

    Comision Federal de Electricidad installed a 600 kW wind turbine in the Guerrero Negro isolated electrical grid to evaluate, under actual operation conditions, the contribution of wind energy in the generation of electricity. This paper describes the performance of the wind turbine in terms of its availability, power curve and electricity produced. The results have been satisfactory, electricity was supplied with a lesser fuel consumption than before. [Spanish] La Comision Federal de Electricidad instalo en Guerrero Negro, Baja California Sur, Mexico un aerogenerador de 600 kW para evaluar en condiciones reales de operacion la integracion de la energia del viento a sistemas electricos aislados basados en diesel. En este trabajo se describen los resultados del primer ano de operacion del aerogenerador en terminos de su disponibilidad, curva de potencia y generacion obtenida. Los resultados han sido satisfactorios, registrandose una reduccion en el consumo de combustible fosil en el sistema.

  6. Occurrence of Highly Mature Organic Matter in Marine Black Shale Petroleum Source Rocks of Basal Cambrian from Northern Tarim Basin, China

    Institute of Scientific and Technical Information of China (English)

    YU Bingsong (于炳松); Hailiang DONG; CHEN Jianqiang (陈建强); CHEN Xiaolin (陈晓林); LIANG Shiyou (梁世友)

    2004-01-01

    More and more evidence indicates that organic matter (OM) in immature organic-rich sediments and sedimentary rocks is chemically adsorbed onto the outer surfaces of minerals and into interlayer (inner) surfaces of smectitic clay minerals in the form of amorphous molecular-scale carbon. But there have been few reports about the occurrence of highly mature OM in marine black shales (petroleum source rocks). The occurrence of highly mature OM in the black shales of basal Cambrian from northern Tarim Basin is studied in this paper. Based on the comprehensive analyses of total organic carbon contents (TOC), maximum thermolysis temperatures (T max ) of OM, mineral surface areas (MSA), and scanning electronic microscopic (SEM) and transmission electronic microscopic (TEM) observations of the black shales, it is concluded that the highly mature OM in the marine black shales of the basal Cambrian from northern Tarim Basin occurs in particulates ranging in size from 1 to 5 μm in diameter. Through the contrast of the occurrence of the highly mature OM in the black shales with that of the immature ones in modern marine continental margin sediments, some scientific problems are proposed, which are worth to study further in detail.

  7. Latest Miocene-earliest Pliocene evolution of the ancestral Rio Grande at the Española-San Luis Basin boundary, northern New Mexico

    Science.gov (United States)

    Daniel J. Koning,; Scott Aby,; Grauch, V. J.; Matthew J. Zimmerer,

    2016-01-01

    We use stratigraphic relations, paleoflow data, and 40Ar/39Ar dating to interpret net aggradation, punctuated by at least two minor incisional events, along part of the upper ancestral Rio Grande fluvial system between 5.5 and 4.5 Ma (in northern New Mexico). The studied fluvial deposits, which we informally call the Sandlin unit of the Santa Fe Group, overlie a structural high between the San Luis and Española Basins. The Sandlin unit was deposited by two merging, west- to southwest-flowing, ancestral Rio Grande tributaries respectively sourced in the central Taos Mountains and southern Taos Mountains-northeastern Picuris Mountains. The river confluence progressively shifted southwestward (downstream) with time, and the integrated river (ancestral Rio Grande) flowed southwards into the Española Basin to merge with the ancestral Rio Chama. Just prior to the end of the Miocene, this fluvial system was incised in the southern part of the study area (resulting in an approximately 4–7 km wide paleovalley), and had sufficient competency to transport cobbles and boulders. Sometime between emplacement of two basalt flows dated at 5.54± 0.38 Ma and 4.82±0.20 Ma (groundmass 40Ar/39Ar ages), this fluvial system deposited 10–12 m of sandier sediment (lower Sandlin subunit) preserved in the northern part of this paleovalley. The fluvial system widened between 4.82±0.20 and 4.50±0.07 Ma, depositing coarse sand and fine gravel up to 14 km north of the present-day Rio Grande. This 10–25 m-thick sediment package (upper Sandlin unit) buried earlier south- to southeast-trending paleovalleys (500–800 m wide) inferred from aeromagnetic data. Two brief incisional events are recognized. The first was caused by the 4.82±0.20 Ma basalt flow impounding south-flowing paleodrainages, and the second occurred shortly after emplacement of a 4.69±0.09 Ma basalt flow in the northern study area. Drivers responsible for Sandlin unit aggradation may include climate

  8. Late Cretaceous dwarf decapods from Guerrero, southern Mexico and their migration patterns

    NARCIS (Netherlands)

    Fraaije, R.H.B.; Vega, F.J.; Bakel, van B.W.M.; Garibay-Romero, L.M.

    2006-01-01

    Two new brachyuran species are described for the Upper Cretaceous Mexcala Formation, Guerrero State, Mexico. Longusorbis quadratus new species (Coniacian, Temalac region) is the oldest and southernmost record for the genus. Xanthosia zoquiapensis new species (Campanian, Zoquiapa region) is the first

  9. Large-scale thrusting along the northern margin of the Tibetan Plateau and the southwest Tarim basin: 230 km long active Hotian thrust sheet

    Science.gov (United States)

    Suppe, J.; Wang, X.; He, D.; Liang, H.

    2015-12-01

    We present the geometry, kinematics and mechanics of large-scale active thrusting in the western Kunlunshan and southwest Tarim basin, which accounts for ~130-165km total shortening of Tarim crust at the northern margin of Tibet. The great frontal structure is the ~230km long bedding-parallel Hotian thrust sheet, which is perhaps the longest active intact thrust sheet in the world, composed of flat-lying strata of the Tarim basin sliding northward on a regional gypsum detachment at the base of the Cenozoic sequence. The toe of the Hotian thrust ramps to the surface two thirds of the way across the Tarim basin, forming the Selibuya-Mazartag hills in the Taklamakan sand desert. At the southern edge of the Tarim basin in the Kunlunshan foothills, a set of high-amplitude anticlines are growing by complex break-forward ramping and wedging in the Hotian thrust sheet as it steps up to the Cenozoic gypsum detachment from a regional Cambrian evaporate detachment that extends under Tibet. More interior structures such as the Tiklik thrust bring older strata and Proterozoic basement to the surface, together with their Cenozoic Tarim cover in the Buya basin. The Cambrian detachment also extends northward under the Tarim basin with minor hanging-wall deformation that locally warps the overlying Hotian thrust sheet, producing a complete syntectonic record in seismically imaged growth strata of its northward motion over these warps. Seismic profiles in the southwest Tarim foothill belt also reveal widespread growth strata that record much of the structural history beginning in the early Pliocene Atushi Formation. Ages of seismic reflectors are calibrated to a surface magnetostratigraphic sequence (Zheng et al., 2000). The beginning of thrusting and folding in the southwest Tarim basin north of the Tiklik thrust is dated at 3.6Ma with shortening >25km and a progressive northward propagation toward the Selibuya-Mazartag hills. The overall shortening rate is ~10 mm/yr. The gypsum

  10. Actual Evapotranspiration in the Al-Khazir Gomal Basin (Northern Iraq Using the Surface Energy Balance Algorithm for Land (SEBAL and Water Balance

    Directory of Open Access Journals (Sweden)

    Hussein Jassas

    2015-04-01

    Full Text Available Increasing dependence on groundwater requires a detailed determination of the different outputs and inputs of a basin for better water management. Determination of spatial and temporal actual evapotranspiration (ETa, in this regard, is of vital importance as there is significant water loss from drainage basins. This research paper uses the Surface Energy Balance Algorithm for Land (SEBAL, as well as the water balance, to estimate the spatial and temporal ETa in the Al-Khazir Gomal Basin, Northern Iraq. To compensate for the shortage in rainfall, and to irrigate summer crops, farmers in this basin have been depending, to a large extent, on groundwater extracted from the underlying unconfined aquifer, which is considered the major source for both domestic and agricultural uses in this basin. Rainfed farming of wheat and barley is one of the most important activities in the basin in the winter season, while in the summer season, agricultural activity is limited to small rice fields and narrow strips of vegetable cultivation along the Al-Khazir River. The Landsat Thematic Mapper images (TM5 acquired on 21 November 2006, 9 March 2007, 5 May 2007, 21 July 2007, and 23 September 2007 were used, along with a digital elevation model (DEM and ground-based meteorological data, measured within the area of interest. Estimation of seasonal ETa from periods between satellite overpasses was computed using the evaporative fraction (Ʌ. The water balance approach was utilized, using meteorological data and river hydrograph analysis, to estimate the ETa as the only missing input in the predefined water balance equation. The results of the two applied methods were comparable. SEBAL results were compared with the land use land cover (LULC map. The river showed the highest ETa, as evaporation from the free-water surface. Rice fields, irrigated in the summer season, have a high ETa in the images, as these fields are immersed in water during June, July and August

  11. Tectonic uplift and sedimentary evolution of the Jiuxi Basin in the northern margin of the Tibetan Plateau since 13 Ma BP

    Institute of Scientific and Technical Information of China (English)

    宋春晖; 方小敏; 李吉均; 高军平; 赵志军; 范马洁

    2001-01-01

    Sediments shed from the northern margin of the Tibetan Plateau, the Qilian Mountains, are widely deposited in the foreland basin, the Jiuxi Basin, archiving plenty of information about the mountain surface uplift and erosion history. The Laojunmiao section, 1960 m thick, representing the upper sequence of the Cenozoic basin sediments, is paleomagnetically dated to about 13-0 Ma BP. Detailed sedimentary study of this sequence has revealed five sedimentary fades associations which determine four stages of sedimentary environment evolution. They are: (I) the half-deep lake system before 12.18 Ma BP, (Ⅱ) the shallow lake system between 12.18 and 8.26 Ma BP, (Ⅲ) the fan delta dominated sedimentary system in dry climate between 8.26 and 6.57 Ma BP, and (IV) alluvial fan system since 6.57 Ma BP. The associated mountain erosion and uplift are suggested to have experienced three phases, that is, tectonic stable (13-8.26 Ma BP), gradual uplift (8.26-<4.96 Ma BP), and rapid intermittent uplift (>3.66-0 Ma BP). Th

  12. Advanced interpretation of land subsidence by validating multi-interferometric SAR data: the case study of the Anthemountas basin (Northern Greece

    Directory of Open Access Journals (Sweden)

    F. Raspini

    2013-10-01

    Full Text Available The potential of repeat-pass space borne SAR (Synthetic Aperture Radar interferometry has been exploited to investigate spatial patterns of land subsidence in the Anthemountas basin, in the northern part of Greece. The PSI (Persistent Scatterer Interferometry approach, based on the processing of long series of SAR acquisitions, has been applied to forty-two images acquired in 1995–2001 by ERS1/2 satellites. Interferometric results have been analysed at a basin scale as support for land motion mapping and at a local scale for the characterisation of ground motion events affecting the village of Perea in the Thermaikos municipality and the "Macedonia" international airport. PSI results revealed a moderate subsidence phenomenon along the wider coastal zone of Anthemountas basin corresponding to intense groundwater extraction. Highest values, exceeding −20 mm yr−1, were measured in the airport area where the thickest sequence of compressible Quaternary sediments occurs. Intense subsidence has been detected also in the Perea village (maximum deformation of −10 to −15 mm yr−1, where a series of fractures, causing damages to both buildings and infrastructure, occurred in 2005–2006.

  13. The stratigraphic record of the Messinian salinity crisis in the northern margin of the Bajo Segura Basin (SE Spain)

    OpenAIRE

    Soria Mingorance, Jesús Miguel; Caracuel Martín, Jesús Esteban; Yébenes Simón, Alfonso; Fernández Martínez, Juan (1945-); Viseras Alarcón, César

    2005-01-01

    The Bajo Segura Basin is a marginal basin of the Western Mediterranean located on the eastern end of the Betic Cordillera (southeastern Spain). Its Messinian and Pliocene stratigraphic record is divided into four allostratigraphic units, with bounding unconformities represented by erosional surfaces corresponding to palaeogeographic changes. The Messinian Unit I (MI) is composed of three depositional systems (fluvial, coastal lagoon, and shelf) which lateral facies changes, deposited...

  14. Platform-induced clay-mineral fractionation along a northern Tethyan basin-platform transect: implications for the interpretation of Early Cretaceous climate change (Late Hauterivian-Early Aptian)

    OpenAIRE

    Godet, Alexis; Bodin, Stéphane; Adatte, Thierry; Föllmi, Karl B.

    2009-01-01

    High-resolution clay-mineral analyses were performed on upper Hauterivian to lower Aptian sediments along a platform-to-basin transect through the northern Tethyan margin from the Neuchâtel area (Switzerland), to the Vocontian Trough (France) in order to investigate links between climate change, carbonate platform evolution, and fractionation patterns in clay minerals during their transport. During the Hauterivian, the northern Tethyan carbonate platform developed in a heterozoan mode, and t...

  15. Estimation of strong ground motions in Mexico City expected for large earthquakes in the Guerrero seismic gap

    OpenAIRE

    Kanamori, Hiroo; Jennings, Paul C.; Singh, Shri Krishna; Astiz, Luciana

    1993-01-01

    We performed simulations of ground motions in Mexico City expected for large earthquakes in the Guerrero seismic gap in Mexico. The simulation method uses as empirical Green's functions the accelerograms recorded in Mexico City during four small to moderate earthquakes (8 Feb. 1988, M_s = 5.8; 25 April 1989, M_w = 6.9; 11 May 1990, M_w = 5.5; and 31 May 1990, M_w = 6.0) in the Guerrero gap. Because these events occurred in the Guerrero gap, and have typical thrust mechanisms, the propagation ...

  16. Detection of detached forced-regressive nearshore wedges: a case study from the central-southern Siena Basin (Northern Apennines, Italy)

    Science.gov (United States)

    Martini, Ivan; Arragoni, Simone; Aldinucci, Mauro; Foresi, Luca Maria; Bambini, Anna Maria; Sandrelli, Fabio

    2013-07-01

    The detection of detached nearshore wedges formed in response to relative sea-level drops is considered one of the hottest topics in sequence stratigraphic analysis due to their importance as reservoir analogues. In fact, they usually constitute sandy and porous bodies generally encased in impermeable clay, thus presenting a good potential as traps for fluids. This paper focuses on the sequence stratigraphic analysis of the Pliocene deposits cropping out in the central-southern sector of the Siena Basin (Tuscany, Italy), a post-collisional basin of the Northern Apennines. The exposed sedimentary succession was investigated through a detailed sedimentological and stratigraphic approach, integrated by biostratigraphic analyses, aimed at a better characterization of the infilling history of this sector of the basin. Specifically, this study revealed the occurrence of repeated facies shifts that allowed the identification of two depositional sequences. In detail, a thick sand-rich body far from the basin margins, and previously considered as a turbiditic lobe, has been reinterpreted as formed in a nearshore setting during a fall in relative sea level. This body is totally encased in offshore clay, and due to the lack of physical connection with the related HST deposits, it has to be considered as a detached forced-regressive wedge. The present work led to the recognition of some sedimentological and stratigraphic features typical of falling stage systems tract deposits (e.g. presence of intrabasinal recycled materials, sedimentological evidence of a pre-existing fluvial network subsequently eroded) that can provide useful clues for the identification of detached forced-regressive nearshore wedges in core studies and poorly exposed settings.

  17. Alkali element enrichments on the BABBs at the IODP Expedition 333 Site C0012 in the northern Shikoku Basin

    Science.gov (United States)

    Haraguchi, S.; Nakamura, K.; Fujinaga, K.

    2015-12-01

    The Shikoku Basin is a back arc basin located westside of the Izu-Ogasawara (Bonin) arc, spreading was from 25 to 15 Ma. The drilling of the DSDP, ODP and IODP recovered the backarc basin basalt (BABB) of the Shikoku Basin. Site C0012, south of the Kii Peninsula, was operated during the IODP Exp 333, and BABB was recovered 100m thickness under the 520m of sediment. This BABB is divided into upper aphyric pillow (Unit 1) and lower massive flow (Unit 2) divided at the 560 mbsf, and show variable degree of alteration, clay mineral and zeolite depositions. SiO2 and MgO contents of these basalts are 47-55 and 5-8 wt%. These basalts show wide variation of enrichment of alkali elements, 2.3-7.5 and 0.4-4.2 wt% of Na2O and K2O. Na2O+K2O contents show 3.2-8.0 wt%, and 2 wt% higher trends than other BABBs in the Shikoku Basin at the same SiO2 contents. Na2O and K2O show proportional and anti-proportional trends with increasing LOI. Therefore, both alkali element enrichments in these rocks are caused by secondary mineralization, and host phase of Na2O is hydrous and that of K2O is anhydrous minerals. Secondary mineral phases was mainly identified by XRD. The identified host phases of Na are analcime and thomsonite. Analcime is observed in rocks of more than 4 wt% of Na2O. Chlorite and smectite are identified to clay minerals. This mineral assemblage indicates the high-temperature zeolite facies alteration. The host phases of K are mainly identified into K-feldspar. We assume that secondary mineralization of K-fd is associated with low-temperature albitization. Compared to the lithostratigraphy, the Na enrichment is prominent in the Unit 1 and upper 20 m of the Unit 2, and the K enrichment is prominent in lower part of the Unit 2. We consider that the Na enrichment associated with zeolite depositions occurred under high water/rock ratio with active hydrothermal circulation because of high water permeability of pillow lava, and K enrichment associated with albitization occurred

  18. Numerical Simulation of Inter-basin Groundwater Flow into Northern Yucca Flat, Nevada National Security Site, Using the Death Valley Regional Flow System Model

    Energy Technology Data Exchange (ETDEWEB)

    Pohlmann Karl,Ye Ming

    2012-03-01

    Models of groundwater flow for the Yucca Flat area of the Nevada National Security Site (NNSS) are under development by the U.S. Department of Energy (DOE) for corrective action investigations of the Yucca Flat-Climax Mine Corrective Action Unit (CAU). One important aspect of these models is the quantity of inter-basin groundwater flow from regional systems to the north. This component of flow, together with its uncertainty, must be properly accounted for in the CAU flow models to provide a defensible regional framework for calculations of radionuclide transport that will support determinations of the Yucca Flat-Climax Mine contaminant boundary. Because characterizing flow boundary conditions in northern Yucca Flat requires evaluation to a higher level of detail than the scale of the Yucca Flat-Climax Mine CAU model can efficiently provide, a study more focused on this aspect of the model was required.

  19. Apuntes para una historia de la insurgencia en la Tierra Caliente de Guerrero, 1810-1821

    Directory of Open Access Journals (Sweden)

    Jesús Guzmán Urióstegui

    2009-06-01

    Full Text Available Durante el periodo de lucha por la independencia de México, de 1810 a 1821, una de las zonas geográficas más destacadas por su apoyo a la insurgencia fue la del Sur, cuyo territorio forma actualmente el estado de Guerrero. Primero con José María Morelos y Pavón y luego con Vicente Guerrero, la complicada geografía suriana y su no menos malsano clima puso en entredicho todos los intentos de las autoridades virreinales por reestablecer ahí la paz. Es cierto que los realistas lograron algunos éxitos, pero nunca pudieron vencer los afanes de libertad de los pobladores del lugar, especialmente de los de Tierra Caliente, mismos que si bien de 1811 a 1813 actuaron de manera en cierta forma aislada, pues Morelos no los tomaba muy en cuenta ya que prefería a los costeños, después fueron su sostén principal. Este papel lo refrendarían de igual manera de 1816 a 1821 con Guerrero, obligando a Agustín de Iturbide a negociar la paz.During Mexico's struggle for independence, from 1810 to 1821, one of the geographical zones that provided most support for the insurgents was the south, whose territory currently forms part of the state of Guerrero. First with José María Morelos y Pavón and then with Vicente Guerrero, the complicated geography of the south and its no less unhealthy climate jeopardized all the viceregal authorities' attempts to re-establish peace there. Although the royalists had some success, they were never able to overcome the locals' desire for freedom, especially those in Tierra Caliente. Although they acted in a somewhat isolated fashion from 1811 to 1813, since Morelos ignored them, preferring those on the coast, they subsequently provided his greatest support. They did the same with Guerrero from 1816 to 1821, forcing Agustín de Iturbide to negotiate peace.

  20. Groundwater flow in a closed basin with a saline shallow lake in a volcanic area: Laguna Tuyajto, northern Chilean Altiplano of the Andes.

    Science.gov (United States)

    Herrera, Christian; Custodio, Emilio; Chong, Guillermo; Lambán, Luis Javier; Riquelme, Rodrigo; Wilke, Hans; Jódar, Jorge; Urrutia, Javier; Urqueta, Harry; Sarmiento, Alvaro; Gamboa, Carolina; Lictevout, Elisabeth

    2016-01-15

    Laguna Tuyajto is a small, shallow saline water lake in the Andean Altiplano of northern Chile. In the eastern side it is fed by springs that discharge groundwater of the nearby volcanic aquifers. The area is arid: rainfall does not exceed 200mm/year in the rainiest parts. The stable isotopic content of spring water shows that the recharge is originated mainly from winter rain, snow melt, and to a lesser extent from some short and intense sporadic rainfall events. Most of the spring water outflowing in the northern side of Laguna Tuyajto is recharged in the Tuyajto volcano. Most of the spring water in the eastern side and groundwater are recharged at higher elevations, in the rims of the nearby endorheic basins of Pampa Colorada and Pampa Las Tecas to the East. The presence of tritium in some deep wells in Pampa Colorada and Pampa Las Tecas indicates recent recharge. Gas emission in recent volcanoes increase the sulfate content of atmospheric deposition and this is reflected in local groundwater. The chemical composition and concentration of spring waters are the result of meteoric water evapo-concentration, water-rock interaction, and mainly the dissolution of old and buried evaporitic deposits. Groundwater flow is mostly shallow due to a low permeability ignimbrite layer of regional extent, which also hinders brine spreading below and around the lake. High deep temperatures near the recent Tuyajto volcano explain the high dissolved silica contents and the δ(18)O shift to heavier values found in some of the spring waters. Laguna Tuyajto is a terminal lake where salts cumulate, mostly halite, but some brine transfer to the Salar de Aguas Calientes-3 cannot be excluded. The hydrogeological behavior of Laguna Tuyajto constitutes a model to understand the functioning of many other similar basins in other areas in the Andean Altiplano.

  1. Public perception of an ecological rehabilitation project in inland river basins in northern China: Success or failure.

    Science.gov (United States)

    Feng, Qi; Miao, Zheng; Li, Zongxing; Li, Jianguo; Si, Jianhua; S, Yonghong; Chang, Zongqiang

    2015-05-01

    The need for environmental protection challenges societies to deal with difficult problems because strategies designed by scientists to protect the environment often create negative effects on impoverished local residents. We investigated the effects of China's national and regional policies related to environmental protection and rehabilitation projects in inland river basins, by studying the effect of projects in the Heihe and Shiyang river basins, in northwest China. Interviews and surveys were conducted at 30 sites in the lower reaches of these two arid basins, an area that has experienced severe ecological degradation. The survey results show the ecological rehabilitation projects adversely affected the livelihoods of 70.35% of foresters, 64.89% of farmers and 62.24% of herders in the Minqing region in the lower Shiyang River Basin; also, the projects negatively affected 51.9% of residents in the Ejin Qi in the lower Heihe River Basin. This caused 16.33% of foresters, 39.90% of farmers and 45.32% of herders in the Minqing region to not support the project and 37.5% of residents in the Ejin Qi region said they will deforest and graze again after the project ends. The negative impacts of the policies connected to the projects cause these attitudes. The projects prohibit felling and grazing and require residents to give up groundwater mining; this results in a great amount of uncompensated economic loss to them. Extensive survey data document the concerns of local residents, concerns that are supported by the calculation of actual incomes. In addition, the surveys results show poorer interviewees believe the projects greatly affected their livelihoods. While citizens in this region support environment protection work, the poor require considerable assistance if one expects them to support this type of work. Governmental assistance can greatly improve their living conditions, and hence encourage them to participate in and support the implementation of the projects

  2. Impact of Cenozoic strike-slip tectonics on the evolution of the northern Levant Basin (offshore Lebanon)

    Science.gov (United States)

    Ghalayini, Ramadan; Daniel, Jean-Marc; Homberg, Catherine; Nader, Fadi H.; Comstock, John E.

    2014-11-01

    Sedimentary basins adjacent to plate boundaries contain key tectonic and stratigraphic elements to understand how stress is transmitted through plates. The Levant Basin is a place of choice to study such elements because it flanks the Levant Fracture System and the Africa/Anatolia boundary. This paper uses new high-quality 3-D seismic reflection data to unravel the tectonic evolution of the margin of this basin during the Cenozoic, the period corresponding to the formation of the Levant Fracture System, part of the Africa/Arabia plate boundary. Four major groups of structures are identified in the interpreted Cenozoic units: NW-SE striking normal faults, NNE-SSW striking thrust-faults, ENE-WSW striking dextral strike-slip faults, and NNE trending anticlines. We demonstrate that all structures, apart of the NW-SE striking normal faults, are inherited from Mesozoic faults. Their reactivation and associated folding started during the late Miocene prior to the Messinian salinity crisis due to a NW-SE compressional stress field. No clear evidence of shortening at present-day offshore Lebanon and no large NNE-SSW strike-slip faults parallel to the restraining bend are found indicating that the Levant Fracture System is mainly contained onshore at present day. The intermittent activity of the interpreted structures correlates with the two stages of Levant Fracture System movement during late Miocene and Pliocene. This paper provides a good example of the impact of the evolution of plate boundaries on adjacent basins and indicates that any changes in the stress field, as controlled by the plate boundary, will affect immediately the preexisting structures in adjacent basins.

  3. Biocenosis de Bivalvia y Polyplacophora del intermareal rocoso en playa Tlacopanocha, Acapulco, Guerrero, México Polyplacophora and Bivalvia biocenosis at rocky intertidal Tlacopanocha beach, Acapulco, Guerrero, Mexico

    Directory of Open Access Journals (Sweden)

    Lizeth Galeana-Rebolledo

    2012-11-01

    Full Text Available El Estado de Guerrero, México, tiene regiones marinas prioritarias para la conservación de su biodiversidad y la información acerca de la diversidad de moluscos es escasa, por lo que es necesario realizar inventarios de especies, estudios de ecología de poblaciones y comunidades. Este estudio se efectuó en el intermareal rocoso de la playa Tlacopanocha. Los objetivos fueron: determinar la riqueza, densidad y diversidad de especies; analizar la composición de especies y estructura de tallas. El área de muestreo fue de 10 m² y la unidad de muestreó fue de 1 m². Se identificaron 35 especies, de las cuales tres son nuevos registros para el intermareal rocoso de Guerrero: las familias mejor representadas en riqueza de especies fueron Ischnochitonidae y Arcidae, y en abundancia Chitonidae y Chamidae; la densidad fue de 31,60 ind m-2. Polyplacophora presentó 42,9% de especies dominantes y Bivalvia 19,0%. Chama corallina presentó la mayor talla en longitud y Chama sordida en ancho. La riqueza de especies de moluscos registrada se considera alta y corresponde a lo esperado para un sustrato rocoso en zona tropical. Polyplacophora presentó alta composición de especies, que podría ser resultado de la adaptación de los organismos a las condiciones dinámicas del intermareal rocoso. Los nuevos registros indican la importancia de los inventarios de especies y también del conocimiento de las poblaciones y comunidades de la fauna marina de Guerrero.The State of Guerrero, Mexico, has priority marine areas for conservation of its biodiversity, but information concerning diversity of mollusks is limited, so it is convenient to carry out species inventories, studies of populations and community ecology. This study was conducted in the intertidal rocky beach Tlacopanocha. The objectives were to determine richness, density and species diversity, analyze the species composition and size structure. The sampling area was 10 m² and the sampling unit was

  4. Registros adicionales de felinos del estado de Guerrero, México Additional records of cats in the state of Guerrero, Mexico

    OpenAIRE

    José Alberto Almazán-Catalán; Cornelio Sánchez-Hernández; Fernando Ruíz-Gutiérrez; María de Lourdes Romero-Almaraz; Alejandro Taboada-Salgado; Elizabeth Beltrán-Sánchez; Leobardo Sánchez-Vázquez

    2013-01-01

    Se amplía la información sobre distribución, hábitat y medidas somáticas y craneales de las 6 especies de felinos que se distribuyen en nuestro país y que se encuentran en Guerrero. La presencia de estas especies se obtuvo a través de métodos directos y registros indirectos. Lynx rufus está representado por la piel y el cráneo de un joven y es el segundo registro para el estado; mientras que Puma concolor, Puma yagouaroundi, Leopardus pardalis, Leopardus wiedii y Panthera onca incrementan su ...

  5. Estudio florístico de Ficus (Moraceae) en el estado de Guerrero, México Floristic study of Ficus (Moraceae) in the state of Guerrero, Mexico

    OpenAIRE

    Carlos Alberto Durán-Ramírez; Rosa María Fonseca-Juárez; Guillermo Ibarra-Manríquez

    2010-01-01

    Con base en salidas al campo y la revisión de ejemplares de herbario, se registran 13 especies de Ficus (Moraceae) en el estado de Guerrero, 4 pertenecen al subgénero Pharmacosycea (F.insípida, F. lapathifolia, F. maxima y F. yoponensis) y 9 al subgénero Urostigma (F. citrifolia, F. cotinifolia, F. crocata, F. membranacea, F. obtusifolia, F. pertusa, F. petiolaris, F. pringlei y F. velutina), al cual se añade un posible registro de F. aurea. Se incluye una clave para su identificación y se pr...

  6. Nitrogen budget in a lowland coastal area within the Po River basin (northern Italy): multiple evidences of equilibrium between sources and internal sinks.

    Science.gov (United States)

    Castaldelli, Giuseppe; Soana, Elisa; Racchetti, Erica; Pierobon, Enrica; Mastrocicco, Micol; Tesini, Enrico; Fano, Elisa Anna; Bartoli, Marco

    2013-09-01

    Detailed studies on pollutants genesis, path and transformation are needed in agricultural catchments facing coastal areas. Here, loss of nutrients should be minimized in order to protect valuable aquatic ecosystems from eutrophication phenomena. A soil system N budget was calculated for a lowland coastal area, the Po di Volano basin (Po River Delta, Northern Italy), characterized by extremely flat topography and fine soil texture and bordering a network of lagoon ecosystems. Main features of this area are the scarce relevance of livestock farming, the intense agriculture, mainly sustained by chemical fertilizers, and the developed network of artificial canals with long water residence time. Average nitrogen input exceeds output terms by ~60 kg N ha(-1) year(-1), a relatively small amount if compared to sub-basins of the same hydrological system. Analysis of dissolved inorganic nitrogen in groundwater suggests limited vertical loss and no accumulation of this element, while a nitrogen mass balance in surface waters indicates a net and significant removal within the watershed. Our data provide multiple evidences of efficient control of the nitrogen excess in this geographical area and we speculate that denitrification in soil and in the secondary drainage system performs this ecosystemic function. Additionally, the significant difference between nitrogen input and nitrogen output loads associated to the irrigation system, which is fed by the N-rich Po River, suggests that this basin metabolizes part of the nitrogen excess produced upstream. The traditionally absent livestock farming practices and consequent low use of manure as fertilizer pose the risk of excess soil mineralization and progressive loss of denitrification capacity in this area.

  7. Combining numerical modeling and stable isotope values to quantify groundwater recharge from the Chilean Andes to the Pampa del Tamarugal Basin, Atacama Desert, northern Chile

    Science.gov (United States)

    Dodd, J. P.; Pollyea, R.

    2014-12-01

    The Atacama Desert of northern Chile is one of the driest regions on Earth and receives less than 5mm of precipitation annually. The Pampa del Tamarugal (PdT) Basin contains the largest aquifer system in the region, yet the mechanisms and timing of aquifer recharge and continental-scale groundwater flux are poorly understood. Although there is little debate that the source of groundwater recharge is the higher elevation regions of the Andean Altiplano to the east of the PdT Basin, there remains much uncertainty surrounding the mechanisms and timing of aquifer recharge and continental-scale groundwater flux. Most recharge models of the PdT focus on surface water runoff and alluvial fan recharge on shorter time scales, but many of these models explicitly neglect deep flow pathways. Previous investigators have combined the thermal aquifer profile and 14C groundwater ages to propose an alternative conceptual model in which cold meteoric water infiltrates deep into the Cordillera before circulating upward into the PdT by thermal convection through fault-controlled migration pathways. Although this conceptual model provides a convincing theoretical argument for deep fluid circulation, it cannot constrain the magnitude of this deep recharge flux. In this work, we revisit deep-flow conceptual model by combining the spatial distribution of hydrogen and oxygen isotope values as groundwater tracers with a non-isothermal model of continental scale groundwater flow through a two-dimensional transect from the Chilean Andes to the PdT Basin. This work provides first-order estimates on the contribution of deep groundwater circulation within the PdT Aquifer, while providing a framework for (1) quantifying boundary conditions for high resolution models of groundwater resources within the PdT Aquifer, (2) assessing the influence of variable future climate scenarios for groundwater availability in the region, and (3) further integrating conservative tracers and numerical models for

  8. Nitrogen Budget in a Lowland Coastal Area Within the Po River Basin (Northern Italy): Multiple Evidences of Equilibrium Between Sources and Internal Sinks

    Science.gov (United States)

    Castaldelli, Giuseppe; Soana, Elisa; Racchetti, Erica; Pierobon, Enrica; Mastrocicco, Micol; Tesini, Enrico; Fano, Elisa Anna; Bartoli, Marco

    2013-09-01

    Detailed studies on pollutants genesis, path and transformation are needed in agricultural catchments facing coastal areas. Here, loss of nutrients should be minimized in order to protect valuable aquatic ecosystems from eutrophication phenomena. A soil system N budget was calculated for a lowland coastal area, the Po di Volano basin (Po River Delta, Northern Italy), characterized by extremely flat topography and fine soil texture and bordering a network of lagoon ecosystems. Main features of this area are the scarce relevance of livestock farming, the intense agriculture, mainly sustained by chemical fertilizers, and the developed network of artificial canals with long water residence time. Average nitrogen input exceeds output terms by ~60 kg N ha-1 year-1, a relatively small amount if compared to sub-basins of the same hydrological system. Analysis of dissolved inorganic nitrogen in groundwater suggests limited vertical loss and no accumulation of this element, while a nitrogen mass balance in surface waters indicates a net and significant removal within the watershed. Our data provide multiple evidences of efficient control of the nitrogen excess in this geographical area and we speculate that denitrification in soil and in the secondary drainage system performs this ecosystemic function. Additionally, the significant difference between nitrogen input and nitrogen output loads associated to the irrigation system, which is fed by the N-rich Po River, suggests that this basin metabolizes part of the nitrogen excess produced upstream. The traditionally absent livestock farming practices and consequent low use of manure as fertilizer pose the risk of excess soil mineralization and progressive loss of denitrification capacity in this area.

  9. Evidence for intercontinental parasite exchange through molecular detection and characterization of haematozoa in northern pintails (Anas acuta) sampled throughout the North Pacific Basin

    Science.gov (United States)

    Ramey, Andy M.; Schmutz, Joel A.; Reed, John A.; Fujita, Go; Scotton, Bradley D.; Casler, Bruce; Fleskes, Joseph P.; Konishi, Kan; Uchida, Kiyoshi; Yabsley, Michael J.

    2015-01-01

    Empirical evidence supports wild birds as playing a role in the interhemispheric exchange of bacteria and viruses; however, data supporting the redistribution of parasites among continents are limited. In this study, the hypothesis that migratory birds contribute to the redistribution of parasites between continents was tested by sampling northern pintails (Anas acuta) at locations throughout the North Pacific Basin in North America and East Asia for haemosporidian infections and assessing the genetic evidence for parasite exchange. Of 878 samples collected from birds in Alaska (USA), California (USA), and Hokkaido (Japan) during August 2011 - May 2012 and screened for parasitic infections using molecular techniques, Leucocytozoon, Haemoproteus, and Plasmodium parasites were detected in 555 (63%), 44 (5%), and 52 (6%) samples, respectively. Using an occupancy modeling approach, the probability of detecting parasites via replicate genetic tests was estimated to be high (p ≥ 0.95). Multi-model inference supported variation of Leucocytozoon parasite prevalence by northern pintail age class and geographic location of sampling in contrast to Haemoproteus and Plasmodium parasites for which there was only support for variation in parasite prevalence by sampling location. Thirty-one unique mitochondrial DNA haplotypes were detected among haematozoa infecting northern pintails including seven lineages shared between samples from North America and Japan. The finding of identical parasite haplotypes at widely distributed geographic locations and general lack of genetic structuring by continent in phylogenies for Leucocytozoon and Plasmodium provides evidence for intercontinental genetic exchange of haemosporidian parasites. Results suggest that migratory birds, including waterfowl, could therefore facilitate the introduction of avian malaria and other haemosporidia to novel hosts and spatially distant regions.

  10. Evidence for intercontinental parasite exchange through molecular detection and characterization of haematozoa in northern pintails (Anas acuta sampled throughout the North Pacific Basin

    Directory of Open Access Journals (Sweden)

    Andrew M. Ramey

    2015-04-01

    Full Text Available Empirical evidence supports wild birds as playing a role in the interhemispheric exchange of bacteria and viruses; however, data supporting the redistribution of parasites among continents are limited. In this study, the hypothesis that migratory birds contribute to the redistribution of parasites between continents was tested by sampling northern pintails (Anas acuta at locations throughout the North Pacific Basin in North America and East Asia for haemosporidian infections and assessing the genetic evidence for parasite exchange. Of 878 samples collected from birds in Alaska (USA, California (USA, and Hokkaido (Japan during August 2011–May 2012 and screened for parasitic infections using molecular techniques, Leucocytozoon, Haemoproteus, and Plasmodium parasites were detected in 555 (63%, 44 (5%, and 52 (6% samples, respectively. Using an occupancy modeling approach, the probability of detecting parasites via replicate genetic tests was estimated to be high (ρ > 0.95. Multi-model inference supported variation of Leucocytozoon parasite prevalence by northern pintail age class and geographic location of sampling in contrast to Haemoproteus and Plasmodium parasites for which there was only support for variation in parasite prevalence by sampling location. Thirty-one unique mitochondrial DNA haplotypes were detected among haematozoa infecting northern pintails including seven lineages shared between samples from North America and Japan. The finding of identical parasite haplotypes at widely distributed geographic locations and general lack of genetic structuring by continent in phylogenies for Leucocytozoon and Plasmodium provides evidence for intercontinental genetic exchange of haemosporidian parasites. Results suggest that migratory birds, including waterfowl, could therefore facilitate the introduction of avian malaria and other haemosporidia to novel hosts and spatially distant regions.

  11. Geophysical evidence for a major palaeochannel within the Obosum Group of the Volta Basin, Northern Region, Ghana

    OpenAIRE

    Jessell, Mark; Boamah, K.; Duodu, J. A.; Ley-Cooper, Y.

    2015-01-01

    We have identified a 230 km long palaeochannel cutting through the sediments of the Obosum Group within the Volta Basin, Ghana. The channel is visible in regional airborne magnetic data as a pair of parallel magnetic anomalies which we interpret to be lateral terrace placer deposits of magnetite or maghemite and show both meandering and braided geometries. The palaeochannel is also visible in the airborne radiometric data for part of its length, as well as in airborne electromagnetic data, wh...

  12. Rotational differencies between the northern and southern Tyrrhenian domains: paleomagnetic constraints from the Amantea basin (Calabria, Italy)

    OpenAIRE

    Speranza, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Mattei, M.; Dipartimento di Scienze Geologiche, Universita` di Roma TRE, Rome; Sagnotti, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Grasso, F.; Dipartimento di Scienze Geologiche, Università di Roma Tre, Largo S. Leonardo Murialdo 1, 00143 Roma, Italy

    2000-01-01

    We report on a palaeomagnetic study of upper Miocene sediments from the Amantea basin, located on the Tyrrhenian coast of Calabria. The magnetic mineralogy is dominated by greigite and subordinate magnetite in the Tortonian-Messinian clays (ten sites), and by hemoilmenite and magnetite in the underlaying sands and volcanic ashes (three sites), which have not been dated. Data from the Tortonian, Messinian clays pass both a reversal and a fold test, and define a 19° ± 11° clockwise rotation (wi...

  13. Niveles de asimilación económica del estado de Guerrero

    Directory of Open Access Journals (Sweden)

    Enrique Propin Frejomil

    1998-01-01

    Full Text Available La teoría de la asimilación económica del territorio es una manera nueva de interpretar la realidad regional del país. Este estudio tiene por finalidad obtener una imagen cartográfica sintética de Guerrero, basada en la consideración de los preceptos centrales de dicha teoría. Tal producto científico es de utilidad en distintos ambitos de la planeación urbana y regional. Los resultados de esta investigación evidencian enormes contrastes dentro de Guerrero, debido al hallazgo de doce niveles de asimilación económica.

  14. Luminescence ages for three 'Middle Palaeolithic' sites in the Nihewan Basin, northern China, and their archaeological and palaeoenvironmental implications

    Science.gov (United States)

    Guo, Yu-Jie; Li, Bo; Zhang, Jia-Fu; Yuan, Bao-Yin; Xie, Fei; Roberts, Richard Graham

    2016-05-01

    The Nihewan Basin is a key region for studying the Palaeolithic archaeology of East Asia. However, because of the lack of suitable dating methods and representative lithic technologies in this region, the 'Middle Palaeolithic' sites in this basin have been designated based mainly on stratigraphic correlation, which may be unreliable. In this study, three Palaeolithic sites, Motianling, Queergou and Banjingzi, which have been assigned previously to the 'Middle Palaeolithic', are dated based on luminescence dating of K-feldspar grains. Our results show that the cultural layers at Motianling, Queergou and Banjingzi have ages of 315 ± 13, 268 ± 13 and 86 ± 4 ka (corresponding to Marine Isotope Stages 9, 8 and 5), respectively, suggesting that Motianling and Queergou should be assigned to the Lower Palaeolithic, while the age of Banjingzi is consistent with a Middle Palaeolithic attribution. Our results suggest that reassessing the age of 'Middle Palaeolithic' sites in the Nihewan Basin, and elsewhere in North China, is crucial for understanding the presence or absence of the Middle Palaeolithic phase in China. Our dating results also indicate that the Sanggan River developed sometime between about 270 and 86 ka ago.

  15. Holocene Paleoseismic Activity Along the Northern Piedmont Fault of the Hengshan Mountain, South of Datong Basin in Shanxi Province

    Institute of Scientific and Technical Information of China (English)

    Jiang Wali; Xie Xinsheng; Wang Huanzhen; Feng Xiying; Zhang Kangfu

    2003-01-01

    Our field investigation indicates that the northern piedmont fault of the Hengshan Mountain hasdislocated proluvial fan and terrace I of the gully mouth on the northern border of theHengshan Mountain. Stratigraphic age data indicates that the surface layer in the middle andrear part of the proluvial fan and on the terrace I of the gully mouth on the mountain borderconsists of sediments of about 5200 ~ 6800a B.P. The Hezhuang and Niucaoyu trenchesexcavated in the front of Hengshan Mountain revealed that 3 paleoseismic events have occurredalong the northern piedmont fault of Hengshan Mountain since the early Holocene. The 3paleoseismic events occurred in 2260 ± 190 ~ 4370 ± 150a BP, nearly 5628 ± 150a BP, and 8083± 250 ~ 8430 ± 720a BP, respectively, and their recurrence interval is 2313a, 2628a and 2471aon average. The coseismic vertical displacement produced by these events is 1.0 ~ 3.0m. Theelapsed time of the latest movement along the fault has exceeded the recurrence interval of thesepaleoearthquakes. Thus, there exists the possibility of strong earthquake occurrence along thefault from now onward, so the fault is in need of observation.

  16. THE COMMUNITY SOCIAL CAPITAL, A STRATEGY AGAINST POVERTY IN INDIGENOUS PEOPLES OF THE STATE OF GUERRERO

    OpenAIRE

    Adrián González-Romo; Juan Maldonado-Montalvo

    2014-01-01

    Indigenous peoples of Guerrero show different tradeoffs in their ways of dealing with such adverse reality that afflicts them , first struggling to maintain the traditions and customs , using their customary community practices to maintain unity and confront the inhumane living conditions through what has been called community organization , considered part of the concept of social capital and the other institutions that do their thing trying to find solutions to this problem , however the me...

  17. Seismicity Variations Associated with Aseismic Transients in Guerrero, Mexico, 1995-2006

    OpenAIRE

    Liu, Yajing; Rice, James R.; Larson, Kristine M.

    2007-01-01

    Primarily aseismic deformation transients in subduction zones, sometimes associated with tremors and low-frequency earthquakes, are a newly recognized mode of deformation. Stressing in the up-dip seismogenic zone is increased episodically due to down-dip transient slips, and each event may make it more prone to failure in a large thrust earthquake. It is important for seismic hazard assessment to search and identify patterns of seismicity variation associated with transients. The Guerrero, Me...

  18. A new species of Stelis (Orchidaceae, Pleurothallidinae from Guerrero, Mexico Una nueva especie de Stelis (Orchidaceae, Pleurothallidinae de Guerrero, México

    Directory of Open Access Journals (Sweden)

    Rodolfo Solano-Gómez

    2007-12-01

    Full Text Available A new species of Stelis from the cloud forest of Guerrero, Mexico, is described and illustrated as S. desantiagoi. This species is similar to S. rubens, but is distinguished by its larger plants, the stems proportionally longer, the leaves wider, the sepals internally papillose (vs. pubescent, the petals flabellate (vs. cuneate, the labellum slightly arcuate with the apex straight (vs. geniculate with the apex strongly incurved, and the clinandrium entire (vs. trilobate.Se describe e ilustra una nueva especie de Stelis del bosque nublado de Guerrero, México como S. desantiagoi. Esta especie es similar a S. rubens, pero se distingue por las plantas de mayor tamaño, los tallos proporcionalmente más largos, las hojas más anchas, los sépalos interiormente papilosos (vs. pubescentes, los pétalos flabelados (vs. cuneados, el labelo ligeramente arqueado con ápice recto (vs. geniculado con el ápice fuertemente incurvado y el clinandrio entero (vs. trilobado.

  19. Registros adicionales de felinos del estado de Guerrero, México Additional records of cats in the state of Guerrero, Mexico

    Directory of Open Access Journals (Sweden)

    José Alberto Almazán-Catalán

    2013-03-01

    Full Text Available Se amplía la información sobre distribución, hábitat y medidas somáticas y craneales de las 6 especies de felinos que se distribuyen en nuestro país y que se encuentran en Guerrero. La presencia de estas especies se obtuvo a través de métodos directos y registros indirectos. Lynx rufus está representado por la piel y el cráneo de un joven y es el segundo registro para el estado; mientras que Puma concolor, Puma yagouaroundi, Leopardus pardalis, Leopardus wiedii y Panthera onca incrementan su área de distribución en el estado. Las principales amenazas para estos felinos son la fragmentación del hábitat y la cacería furtiva.Information on distribution, habitat and measurements of the 6 species of cats found in Mexico and in Guerrero is provided. The specimens were recorded through direct and indirect methods. Lynx rufus is represented by the skin and skull of a young specimen and it is the second record for the state, while Puma concolor, Puma yagouaroundi, Leopardus pardalis, Leopardus wiedii and Panthera onca increase its distribution range in the state. The main threats to cats are habitat fragmentation and poaching.

  20. Modelling runoff and glacier melt in the Hunza basin in northern Pakistan using satellite remote sensing techniques

    International Nuclear Information System (INIS)

    The glaciers in western Karakoram are important for freshwater supply in the rivers of Pakistan. Global warming influences the future water supply from glaciers. In order to study the hydrological conditions and possible impacts of climate change, runoff simulations are performed for the Hunza basin. The hydrological modelling system SRM (Snowmelt Runoff Model) is customized and applied to the Hunza basin. Various data obtained from satellite remote sensing imagery and meteorological stations in the study area are processed, prepared and used as input to SRM. For runoff simulations the basin is divided into five sub-basins. The (sub-) basins are defined by the hydrological response units (HRU) based on the elevation zones and land-cover types. The spatially distributed data are aggregated HRU-wise as input for the model simulations. The energy available for snow and glacier melt is parameterized in SRM by degree day factors which are defined separately for seasonal snow, ice and debris covered glaciers. The model is calibrated for the Hunza basin using the meteorological and remote sensing data from years 2002 and 2003. The daily runoff is simulated and compared with the measured discharge data obtained from the power company. The Nash-Sutcliffe correlation coefficient of simulated versus measured runoff data is 0.87 for year 2002 and 0.96 for year 2003 which indicates a good agreement. An estimation of mass balance of Baltoro glacier is made using the meteorological data from Shigar station applying the hydrological method to estimate accumulation and melt. Based on these data is found that Baltoro glacier has slightly negative mass balance. The ablation rates of debris covered parts of Baltoro glacier at 4150 m elevation are estimated to be between 3 and 4 cm per day. However, the uncertainty in mass balance modelling is high due to poor knowledge of accumulation inferred by spatial extrapolation from station data.Keeping the glacier area unchanged, for the 2002

  1. The thick-bedded tail of turbidite thickness distribution as a proxy for flow confinement: Examples from tertiary basins of central and northern Apennines (Italy)

    Science.gov (United States)

    Marini, Mattia; Felletti, Fabrizio; Milli, Salvatore; Patacci, Marco

    2016-07-01

    This study reviews the thickness statistics of non-channelized turbidites from four tertiary basins of Central-Northern Apennines (Italy), where bed geometry and sedimentary character have been previously assessed. Though very different in terms of size and, arguably, character of feeder system, these basins share a common stratigraphic evolution consisting in transition from an early ponded to a late unconfined setting of deposition. Based on comparison of thickness subsets from diverse locations and stratigraphic heights within the studied turbidite fills, this paper seeks to answer the following questions: i) how data collection procedures and field operational constraints (e.g. measure location, outcrop quality, use of thicknesses data from single vs. multiple correlative sections, stratigraphic thickness of the study interval) can affect statistics of sample data? ii) how depositional controls of confined vs. unconfined turbidite basins can result in different thickness-frequency distributions?; and iii) is there in thickness statistics a 'flow confinement' signature which can be used to distinguish between confined and unconfined turbidites? Results suggest that: i) best practices of data collection are crucial to a meaningful interpretation of sample data statistics, especially in presence of stratigraphic and spatial trends of turbidite bed thickness; ii) a systematic bias against cm-thick Tcd Bouma sequence turbidites exists in sample data, which can result in the low-end tail of empirical thickness-frequency distributions to depart significantly from the actual distribution of turbidite thickness; and iii) thickness statistics of beds starting with a basal Ta/Tb Bouma division bear a coherent relationship to the transition from ponded to unconfined depositional settings, consisting in reduction of variance and mean and, consequently, parameters, or even type, of best fit model distribution. This research highlights the role of flow stripping, sediment by

  2. Development of a systemwide predator control program: Stepwise implementation of a predator index, predator control fisheries, and evaluation plan in the Columbia River basin (Northern Squawfish Management Program). Section 1: Implementation; Annual report 1995

    International Nuclear Information System (INIS)

    The authors report their results from the fifth year of a basinwide program to harvest northern squawfish (Ptychocheilus oregonensis) in an effort to reduce mortality due to northern squawfish predation on juvenile salmonids during their emigration from natal streams to the ocean. Earlier work in the Columbia River Basin suggested predation by northern squawfish on juvenile salmonids may account for most of the 10--20% mortality juvenile salmonids experience in each of eight Columbia and Snake River reservoirs. Modeling simulations based on work in John Day Reservoir from 1982 through 1988 indicated that if predator-sized northern squawfish were exploited at a 10--20% rate, the resulting restructuring of their population could reduce their predation on juvenile salmonids by 50%

  3. Development of the alluvial and lacustrine terraces on the northern margin of the Hetao Basin, Inner Mongolia, China: Implications for the evolution of the Yellow River in the Hetao area since the late Pleistocene

    Science.gov (United States)

    Jia, Liyun; Zhang, Xujiao; Ye, Peisheng; Zhao, Xitao; He, Zexin; He, Xiangli; Zhou, Qingshuo; Li, Jie; Ye, Mengni; Wang, Zhen; Meng, Jing

    2016-06-01

    Terrace formation processes can reflect the evolution of large rivers. The Hetao Basin is a floodplain of the Yellow River, and there are two to three terraces that extend E-W on the northern margin. Based on a detailed field geological survey and measurement of the terrace sections, combined with sedimentological and chronological analyses, we reconstructed the developmental processes of the three terraces and inferred that three river terraces were formed by the Yellow River. The OSL dating results show that the time of deposition of terrace 3 was prior to 118 ka BP. Subsequently, the terrace began to experience incision and formed the geomorphic surface of terrace T3. Similarly, terrace 2 and terrace 1 were mainly deposited from ~ 109 and 59 ka, respectively; and began to be incised prior to 71 and 46 ka, respectively. The three terraces in the northern Hetao Basin are the products of the combined actions of climatic shifts and tectonic uplift. The Yellow River's evolutionary history in the Hetao area since the Late Pleistocene is discussed. Before about 120 ka BP, the Yellow River may have flowed through the northern Hetao Basin. Between 110 and 70 ka BP, the Yellow River experienced at least two changes between river and lake sedimentation. From 60 to 50 ka, a very large river-connected lake of the Yellow River was developed in the Hetao Basin. After 50 ka, the Hetao river-connected paleolake of the Yellow River gradually dried.

  4. Microstructural and geochronology data of the Coacoyulillo-Intzcuinatoyac sector rocks, Guerrero state, Mexico

    Science.gov (United States)

    Espejo Bautista, G.; Hernandez, T.; Elías, M.; Solari, L.

    2013-12-01

    The south of Mexico is constituted by many conjugated geological events with volcanic, sedimentary, tectonic, plutonic and metamorphic sequences. The exposed evidences establish the pieces of a complex puzzle which were analyzed in this study for geochronological and structural purposes in context with the observed field relationships. According to Campa and Coney (1983), Mexico is constituted by sixteen tectonostratigraphic terranes, which are distinguished by their basement petrology, although they can superficially share an identical geological record. The study area is located in a triple point where the Xolapa, Guerrero and Mixteca terranes converge and covers the adjacent areas to the Intzcuinatoyac and Coacoyulillo villages, southwest of the city of Chilpancingo in the Guerrero state. This study was performed in a region which is integrated by geological events covered by ductile-fragile regional deformation of great magnitude, consisting of mylonitic rocks and less than 60 to 132 Ma magmatic events, associated with a subduction scenario. The analyzed magmatic events are geographically distributed along the El Zapote and El Reparo rivers and can be classified into three different magmatic pulses, determined by field relations and geochronological data. However, the age of the deformations and deformational events were constrained by two or more magmatic and / or tectonic events. The oldest magmatism is represented by felsic intrusive rocks, which were later affected by ductile deformation, developing mylonitic textures. The deformed intrusive forms part of a mylonitic sector associated to a tectonic contact between the Xolapa, Mixteca and Guerrero terranes. This mylonitic sector can be correlated with other mylonitic areas within the state of Guerrero due to its ductile structural features and its geochronology, such as La Venta and the Ocotito areas. The mylonitic areas of Guerrero form a belt that may be associated with the Chacalapa fault in the state of

  5. A Side-by-side Comparison of Eddy Covariance and Bowen Ratio Evapotranspiration From a Northern Great Basin Ecosystem

    Science.gov (United States)

    Lyles, B. F.; Jasoni, R. L.

    2008-12-01

    Development of new ground water resources in rural lands surrounding urban areas of the arid western United States has been identified as a key to maintaining urban growth. The extent and rate at which ground water can be sustainably extracted, while minimizing environmental impacts, depends to a large degree on how much of the existing resource escapes back to the atmosphere via the process of evapotranspiration (ET). ET is the sum of water that evaporates (E) from soil surfaces and is transpired (T) from plant leaves. This study was conducted in a northeast/southwest trending closed basin, bounded by mountains on all sides, with no surface water outflow. The playa which is located in the center of the basin encompasses 59,600 hectares, while phreatophytic plants bordering the playa encompass 20,000 hectares. ET data was collected from a sagebrush/greasewood plant community from October 2004 to August 2008 by the Bowen Ratio technique. Eddy covariance ET monitoring equipment was installed in April of 2007 and a side-by-side comparison was conducted from April to October, 2007. At the end of the study period a 25% difference in ET was calculated between the eddy covariance and Bowen ratio techniques. The major factors for the differences in ET from the two different methods will be presented.

  6. Late Cretaceous-recent tectonic assembly of diverse crustal blocks in Central America, the Nicaraguan Rise, the Colombian Basin and northern South America as seen on a 1600-km-long, geologic and structural transect

    Science.gov (United States)

    Sanchez, J.; Mann, P.

    2015-12-01

    We have constructed a 1600-km-long transect from northern Honduras to northern Colombia that crosses northeastward-striking crustal blocks using a combination of offshore seismic data, gravity and magnetic data, well subsidence information, nearby outcrop information, and results from previous thermochronological, geochronological, geochemical and paleostress studies. The transect defines three major crustal and structural provinces: 1) Precambrian-Paleozoic, Chortis continental block whose northern edge is defined by the North America-Caribbean plate boundary. Events in this ~20-25-km-thick province include two major unconformities at the top of the Cretaceous and Eocene, associated southeast-dipping thrust faults related to collision of the Great Arc of the Caribbean (GAC) and Caribbean Large Igneous Province (CLIP) with the Chortis continental block. A third event is Eocene to recent subsidence and transtensional basins formed during the opening of the Cayman trough; 2) Late Cretaceous GAC and CLIP of oceanic arc and plateau origin, whose northern, deformed edge corresponds to the mapped Siuna belt of northern Nicaragua. This crustal province has a ~15-20-km-thick crust and is largely undeformed and extends across the Lower Nicaraguan Rise, Hess fault, to the southern limit of the Colombian basin where about 300 km of this province has been subducted beneath the accretionary wedge of the South Caribbean deformed belt of northwestern South America; and 3) Eocene to recent accretionary prism and intramontane basins on continental crust of northern South America, where Miocene accelerated exhumation and erosion of Paleogene and Cretaceous rocks reflect either shallow subduction of the CLIP or the Panama collisional event to the southwest.

  7. Present geotemperature and its suggestion to natural gas generation in Xujiaweizi fault-depression of the northern Songliao Basin

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    According to stastistic of present geotemperatures at the depths of 1000,2000,3000 and 4000 m,respectively in the Xujiaweizi fault-depression of the north Songliao Basin,the result indicates that Xujiaweizi fault-depression falls in the high geotemperature area,with the higher geothermal gradient in the depression layer than that in the fault-depression layer.The geothermal gradient decreases with the increasing of the depth.The thermal conductivity of rock greatly controls the geothermal gradient.The main factors constraining the current geotemperature include thermal configuration of the earth’s crust, deep faults,distribution and abundance of radioelements.The high geotemperature is in favour of generation of deep gas.

  8. Diamond drilling for geologic information in the middle Precambrian basins in the western portion of northern Michigan. Final report

    International Nuclear Information System (INIS)

    Between September 26, 1977, and May 11, 1978, six initially vertical holes probed a total of 9896 feet (1109 feet or 11.2% in overburden, 155 feet or 1.6% in Precambrian Y mafic dikes, 8386 feet or 84.7% in Precambrian X Goodrich Quartzite and Michigamme Formation, and 246 feet or 2.5% in Precambrian W basement lithologies). In addition to normal examination of core, logging, and storing of core, the holes were extensively logged geophysically, acidized core was tested for phosphate content by ammonium molybdate, splits from five out of every thirty feet of core were subjected to chemical scrutiny, thin sections of all lithologies were examined, and radiometric determinations of geologic age were made for confirmation of Precambrian W basement which was encountered in each of the three basins in Marquette County

  9. Mid-Wisconsin to Holocene permafrost and landscape dynamics based on a drained lake basin core from the northern Seward Peninsula, northwest Alaska

    Science.gov (United States)

    Lenz, Josefine; Grosse, Guido; Jones, Benjamin M.; Anthony, Katey M. Walter; Bobrov, Anatoly; Wulf, Sabine; Wetterich, Sebastian

    2016-01-01

    Permafrost-related processes drive regional landscape dynamics in the Arctic terrestrial system. A better understanding of past periods indicative of permafrost degradation and aggradation is important for predicting the future response of Arctic landscapes to climate change. Here, we used a multi-proxy approach to analyse a ~ 4 m long sediment core from a drained thermokarst lake basin on the northern Seward Peninsula in western Arctic Alaska (USA). Sedimentological, biogeochemical, geochronological, micropalaeontological (ostracoda, testate amoebae) and tephra analyses were used to determine the long-term environmental Early-Wisconsin to Holocene history preserved in our core for central Beringia. Yedoma accumulation dominated throughout the Early to Late-Wisconsin but was interrupted by wetland formation from 44.5 to 41.5 ka BP. The latter was terminated by the deposition of 1 m of volcanic tephra, most likely originating from the South Killeak Maar eruption at about 42 ka BP. Yedoma deposition continued until 22.5 ka BP and was followed by a depositional hiatus in the sediment core between 22.5 and 0.23 ka BP. We interpret this hiatus as due to intense thermokarst activity in the areas surrounding the site, which served as a sediment source during the Late-Wisconsin to Holocene climate transition. The lake forming the modern basin on the upland initiated around 0.23 ka BP and drained catastrophically in spring 2005. The present study emphasises that Arctic lake systems and periglacial landscapes are highly dynamic and that permafrost formation as well as degradation in central Beringia was controlled by regional to global climate patterns as well as by local disturbances.

  10. Permian paleogeography of west-central Pangea: Reconstruction using sabkha-type gypsum-bearing deposits of Parnaíba Basin, Northern Brazil

    Science.gov (United States)

    Abrantes, Francisco R.; Nogueira, Afonso C. R.; Soares, Joelson L.

    2016-07-01

    Extreme aridity during Late Permian - Early Triassic period was the main factor for resetting the entire paleoclimate of the planet. Permian evaporite basins and lacustrine red beds were widely distributed along the supercontinent of Pangea. Sulphate deposits in Western Pangea, particularly in Northern Brazil, accumulated in an extensive playa lake system. Outcrop-based facies and stratigraphic analysis of up to 20 m thick evaporite-siliciclastic deposits reveal the predominance of laminated reddish mudstone with subordinate limestone, marl and lenses of gypsum. The succession was deposited in shallow lacustrine and inland sabkha environments associated with saline pans and mudflats. Gypsum deposits comprise six lithofacies: 1) bottom-growth gypsum, 2) nodular/micronodular gypsum, 3) mosaic gypsum, 4) fibrous/prismatic gypsum, 5) alabastrine gypsum, and 6) rosettes of gypsum. Gypsum types 1 and 2 are interpreted as primary deposition in saline pans. Bottom-growth gypsum forms grass-like crusts while nodular/micronodular gypsum indicates displacive precipitation of the crust in shallow water and the groundwater capillary zone. Types 3 and 4 are early diagenetic precipitates. Abundant inclusions of tiny lath-like anhydrite crystals suggest a primary origin of anhydrite. Alabastrine gypsum, fibrous gypsum (satinspar) and rosettes of gypsum probably derived from near-surface hydration of anhydrite. The gypsum-bearing deposits in the Parnaíba Basin contribute towards understanding paleogeographic changes in Western Pangea. A progressive uplift of East Pangea, culminated in the forced regression and retreat of epicontinental seas to the West. Restricted seas or large lakes were formed before the definitive onset of desert conditions in Pangea, leading to the development of extensive ergs.

  11. Constraints on the duration of the Paleocene-Eocene Thermal Maximum by orbitally-influenced fluvial sediment records of the northern Bighorn Basin, Wyoming, USA

    Science.gov (United States)

    van der Meulen, Bas; Abels, Hemmo; Meijer, Niels; Gingerich, Philip; Lourens, Lucas

    2016-04-01

    The addition of major amounts of carbon to the exogenic carbon pool caused rapid climate change and faunal turnover during the Paleocene-Eocene Thermal Maximum (PETM) around 56 million years ago. Constraints are still needed on the duration of the onset, main body, and recovery of the event. The Bighorn Basin in Wyoming provides expanded terrestrial sections spanning the PETM and lacking the carbonate dissolution present in many marine records. Here we provide new carbon isotope records for the Polecat Bench and Head of Big Sand Coulee sections, two parallel sites in the northern Bighorn Basin, at unprecedented resolution. Cyclostratigraphic analysis of these fluvial sediment records using descriptive sedimentology and proxy records allows subdivision into intervals dominated by avulsion deposits and intervals dominated by overbank deposits. These sedimentary sequences alternate in a regular fashion and are related to climatic precession. Correlation of the two, 8-km-spaced sections shows that the avulsion-overbank cycles are laterally consistent. The presence of longer-period alternations, related to modulation by the 100-kyr eccentricity cycle, corroborates the precession influence on the sediments. Sedimentary cyclicity is then used to develop a floating precession-scale age model for the PETM carbon isotope excursion (CIE). We find a CIE body encompassing 95 kyrs aligning with marine cyclostratigraphic age models. The duration of the CIE onset is estimated at 5 kyrs, but difficult to determine because sedimentation rates vary at the sub-precession scale. The CIE recovery starts with a 2 to 4 per mille step and lasts 40 or 90 kyrs, depending on what is considered the carbon isotope background state.

  12. Subaqueous landslides at the distal basin of Lago Nahuel Huapi (Argentina): Towards a tsunami hazard evaluation in Northern Patagonian lakes

    Science.gov (United States)

    Beigt, Débora; Villarosa, Gustavo; Gómez, Eduardo A.; Manzoni, Carolina

    2016-09-01

    The May 22nd, 1960 Valdivia earthquake, Chile (Mw 9.5) triggered a series of subaqueous mass-wasting processes (debris flows and slides) in Lago Nahuel Huapi (Argentina), generating a tsunami-like wave that hit the coasts of San Carlos de Bariloche. Aiming to provide a first preliminary insight into tsunami hazards for the lakeshore communities, in this paper we identify and characterize the subaqueous landslides at the populated distal basin of the lake. Swath bathymetric and seismic profiling surveys were carried out and high-resolution digital elevation models were derived from these data to perform a landslide inventory map. A series of morphometrical parameters (including the landslide area, the volume of displaced materials and the run-out distance, among others) were estimated upon selected events. The results indicated that landslide activity at the distal basin of Lago Nahuel Huapi has been concentrated in the vicinity of Bariloche (massive landslide triggered by the 1960 earthquake) and within steep delta fronts where the slope failures typically initiate at shallow waters (9-11 m depth). The sliding mass frequently travels basinward along a great distance (≥ 1000 m). At the delta fronts, the volume of material removed by landslides can reach ~ 40 × 104 m3, leaving scar areas of up to 13 m thick. The periodic occurrence of rotational-translational mass movements initiating at the upper edge of the delta fronts, with vertical displacements of the mobilized materials reaching ~ 200 m, probably represents a potential tsunami hazard for the nearby populated coasts.

  13. Drainage basin and topographic analysis of a tropical landscape: Insights into surface and tectonic processes in northern Borneo

    Science.gov (United States)

    Mathew, Manoj Joseph; Menier, David; Siddiqui, Numair; Ramkumar, Mu.; Santosh, M.; Kumar, Shashi; Hassaan, Muhammad

    2016-07-01

    We investigated the recent landscape development of Borneo through geomorphic analysis of two large drainage basins (Rajang and Baram basins). The extraction of morphometric parameters utilizing digital terrain data in a GIS environment, focusing on hydrography (stream length-gradient index, ratio of valley floor width to valley height, and transverse topographic symmetry factor) and topography (local relief and relief anomaly), was carried out in order to elucidate processes governing drainage and landscape evolution. Anomalously high and low values of stream length-gradient indices of main tributary streams associated with faults and multiple knick-points along the channel profiles are linked to deformation events. The development of deeply incised V-shaped valleys show enhanced incision capability of streams in response to steepening of hillslope gradients following tectonic inputs. Deflection of streams and probable dynamic reorganization of the drainage system through stream capture processes as feedbacks to tectonic uplift and orographic effect are observed. Local relief and relief anomaly maps highlight the presence of preserved elevation-accordant relict portions of landscapes characterized by low amplitude relief, nested between ridgelines in regions of complex folding. Our results reveal dynamic geomorphic adjustment of the landscape due to perturbations in tectonic and climatic boundary conditions. The implication is that the landscape of north Borneo experienced a tectonic phase of rapid uplift after 5 Ma and undergoes active folding of the Rajang Group thrust belts in the present-day. Active shortening combined with high rates of denudation in Sarawak, demonstrates transience emphasized by the drainage system attempting to adjust to tectonic and climatic forcing.

  14. Whole water column distribution and carbon isotopic composition of bulk particulate organic carbon, cholesterol and brassicasterol from the Cape Basin to the northern Weddell Gyre in the Southern Ocean

    OpenAIRE

    Cavagna, Anne-Julie; F. Dehairs; Woule-Ebongué, V.; Bouillon, Steven; F. Planchon; Delille, Bruno; Bouloubassi, Ioanna

    2012-01-01

    International audience The combination of concentrations and δ13C signatures of Particulate Organic Carbon (POC) and sterols provides a powerful approach to study ecological and environmental changes both in the modern and ancient ocean, but its application has so far been restricted to the surface area. We applied this tool to study the biogeochemical changes in the modern ocean water column during the BONUS-GoodHope survey (Feb-Mar 2008) from Cape Basin to the northern part of the Weddel...

  15. Post-Seismic Deformation from the 2009 Mw 6.3 Dachaidan Earthquake in the Northern Qaidam Basin Detected by Small Baseline Subset InSAR Technique

    Directory of Open Access Journals (Sweden)

    Yang Liu

    2016-02-01

    Full Text Available On 28 August 2009, one thrust-faulting Mw 6.3 earthquake struck the northern Qaidam basin, China. Due to the lack of ground observations in this remote region, this study presents high-precision and high spatio-temporal resolution post-seismic deformation series with a small baseline subset InSAR technique. At the temporal scale, this changes from fast to slow with time, with a maximum uplift up to 7.4 cm along the line of sight 334 days after the event. At the spatial scale, this is more obvious at the hanging wall than that at the footwall, and decreases from the middle to both sides at the hanging wall. We then propose a method to calculate the correlation coefficient between co-seismic and post-seismic deformation by normalizing them. The correlation coefficient is found to be 0.73, indicating a similar subsurface process occurring during both phases. The results indicate that afterslip may dominate the post-seismic deformation during 19–334 days after the event, which mainly occurs with the fault geometry and depth similar to those of the c-seismic rupturing, and partly extends to the shallower and deeper depths.

  16. Sea-level and climate changes in the Northern Calcareous Alps: New insights from the Rhaetian Zlambach Formation of the Hallstatt Basin (Austria)

    Science.gov (United States)

    Clémence, Marie-Emilie; Mette, Wolfgang

    2016-04-01

    The uppermost Triassic (Rhaetian) Zlambach Formation, as developed in the Northern Calcareous Alps of Austria was deposited in the basinal realm of the open marine deeper Hallstatt shelf of the Tethys Ocean. The main part of the Zlambach Formation succession consists of sedimentary sequences, each divided into three parts: (1) a medium-grained intraclastic pack-, grainstone at the base, overlapped by (2) a calcisiltite/calcilutite and finally (3) a calcilutite mudstone at the top of the sequence. Field, microfacies, stable isotope and trace element investigations suggest that the medium-grained intraclastic-bioclastic pack-, grainstones are predominantly allochthonous origin, having been derived as a detrital carbonate signal from the adjacent southern marginal Dachstein reef, while the calcilutite mudstones were mainly composed of pelagic sediments and grains. Thus, the compositional variation of the microfacies inferred to result from gravity-induced carbonate deposits, which are in accordance a distal toe-of-slope setting of the calciturbiditic sequences. In this study, it is postulated that the calciturbidites were deposited in response to regional and/or global eustatic variations. A model is presented in which the basinward export of detrital carbonate was negligible during sea-level lowstands, increasing to a maximum during sea-level highstands. These sea-level variations may be either climate-induced or related to tectonic processes or a combination of both.

  17. Occurrence of arsenic species in algae and freshwater plants of an extreme arid region in northern Chile, the Loa River Basin.

    Science.gov (United States)

    Pell, Albert; Márquez, Anna; López-Sánchez, José Fermín; Rubio, Roser; Barbero, Mercedes; Stegen, Susana; Queirolo, Fabrizio; Díaz-Palma, Paula

    2013-01-01

    This study reports data on arsenic speciation in two green algae species (Cladophora sp. and Chara sp.) and in five aquatic plants (Azolla sp., Myriophyllum aquaticum, Phylloscirpus cf. desserticola, Potamogeton pectinatus, Ruppia filifolia and Zannichellia palustris) from the Loa River Basin in the Atacama Desert (northern Chile). Arsenic content was measured by Mass spectrometry coupled with Inductively Coupled Plasma (ICP-MS), after acidic digestion. Liquid chromatography coupled to ICP-MS was used for arsenic speciation, using both anionic and cationic chromatographic exchange systems. Inorganic arsenic compounds were the main arsenic species measured in all samples. The main arsenic species in the extracts of freshwater algae and plants were arsenite and arsenate, whereas glycerol-arsenosugar (gly-sug), dimethylarsinic acid (DMA) and methylarsonic acid (MA) were present only as minor constituents. Of the samples studied, algae species accumulated more arsenic than aquatic plants. Total arsenic content ranged from 182 to 11100 and from 20 to 248 mg As kg(-1) (d.w.) in algae and freshwater plants, respectively. In comparison with As concentration in water samples, there was hyper-accumulation (>0.1% d.w.) in Cladophora sp. PMID:22981629

  18. Investigation on the hydrodynamics of Ganga Alluvial Plain using environmental isotopes: a case study of the Gomati River Basin, northern India

    Science.gov (United States)

    Singh, Munendra; Kumar, Sudhir; Kumar, Bhishm; Singh, Sandeep; Singh, Indra Bir

    2013-05-01

    An investigation using environmental isotopes (δ18O and δD) was conducted to gain insight into the hydrological processes of the Ganga Alluvial Plain, northern India. River-water, shallow-groundwater and lake-water samples from the Gomati River Basin were analyzed. During the winter season, the δ18O and δD compositions of the Gomati River water ranged from -1.67 to -7.62 ‰ and -25.08 to -61.50 ‰, respectively. Deuterium excess values in the river water (+0.3 to -13 ‰) and the lake water (-20 ‰) indicate the significance of evaporation processes. Monthly variation of δ18O and δD values of the Gomati River water and the shallow groundwater follows a similar trend, with isotope-depleted peaks for δ18O and δD synchronized during the monsoon season. The isotopically depleted peak values of the river water (δ18O = -8.30 ‰ and δD = -57.10 ‰) can be used as a proxy record for the isotopic signature of the monsoon precipitation in the Ganga Alluvial Plain.

  19. Enrichment of fluoride in groundwater under the impact of saline water intrusion at the salt lake area of Yuncheng basin, northern China

    Science.gov (United States)

    Gao, Xubo; Wang, Yanxin; Li, Yilian; Guo, Qinghai

    2007-12-01

    Long-term intake of high-fluoride groundwater causes endemic fluorosis. This study, for the first time, discovered that the salt lake water intrusion into neighboring shallow aquifers might result in elevation of fluoride content of the groundwater. Two cross-sections along the groundwater flow paths were selected to study the geochemical processes controlling fluoride concentration in Yuncheng basin, northern China. There are two major reasons for the observed elevation of fluoride content: one is the direct contribution of the saline water; the other is the undersaturation of the groundwater with respect to fluorite due to salt water intrusion, which appears to be more important reason. The processes of the fluorine activity reduction and the change of Na/Ca ratio in groundwater induced by the intrusion of saline water favor further dissolution of fluorine-bearing mineral, and it was modeled using PHREEQC. With the increase in Na concentration (by adding NaCl or Na2SO4 as Na source, calcium content kept invariable), the increase of NaF concentration was rapid at first and then became slower; and the concentrations of HF, HF{2/-}, CaF+, and MgF+ were continuously decreasing. The geochemical conditions in the study area are advantageous to the complexation of F- with Na+ and the decline of saturation index of CaF2, regardless of the water type (Cl-Na or SO4-Na type water).

  20. Post-Seismic Deformation from the 2009 Mw 6.3 Dachaidan Earthquake in the Northern Qaidam Basin Detected by Small Baseline Subset InSAR Technique.

    Science.gov (United States)

    Liu, Yang; Xu, Caijun; Wen, Yangmao; Li, Zhicai

    2016-01-01

    On 28 August 2009, one thrust-faulting Mw 6.3 earthquake struck the northern Qaidam basin, China. Due to the lack of ground observations in this remote region, this study presents high-precision and high spatio-temporal resolution post-seismic deformation series with a small baseline subset InSAR technique. At the temporal scale, this changes from fast to slow with time, with a maximum uplift up to 7.4 cm along the line of sight 334 days after the event. At the spatial scale, this is more obvious at the hanging wall than that at the footwall, and decreases from the middle to both sides at the hanging wall. We then propose a method to calculate the correlation coefficient between co-seismic and post-seismic deformation by normalizing them. The correlation coefficient is found to be 0.73, indicating a similar subsurface process occurring during both phases. The results indicate that afterslip may dominate the post-seismic deformation during 19-334 days after the event, which mainly occurs with the fault geometry and depth similar to those of the c-seismic rupturing, and partly extends to the shallower and deeper depths. PMID:26861330

  1. Post-Seismic Deformation from the 2009 Mw 6.3 Dachaidan Earthquake in the Northern Qaidam Basin Detected by Small Baseline Subset InSAR Technique

    Science.gov (United States)

    Liu, Yang; Xu, Caijun; Wen, Yangmao; Li, Zhicai

    2016-01-01

    On 28 August 2009, one thrust-faulting Mw 6.3 earthquake struck the northern Qaidam basin, China. Due to the lack of ground observations in this remote region, this study presents high-precision and high spatio-temporal resolution post-seismic deformation series with a small baseline subset InSAR technique. At the temporal scale, this changes from fast to slow with time, with a maximum uplift up to 7.4 cm along the line of sight 334 days after the event. At the spatial scale, this is more obvious at the hanging wall than that at the footwall, and decreases from the middle to both sides at the hanging wall. We then propose a method to calculate the correlation coefficient between co-seismic and post-seismic deformation by normalizing them. The correlation coefficient is found to be 0.73, indicating a similar subsurface process occurring during both phases. The results indicate that afterslip may dominate the post-seismic deformation during 19–334 days after the event, which mainly occurs with the fault geometry and depth similar to those of the c-seismic rupturing, and partly extends to the shallower and deeper depths. PMID:26861330

  2. Geophysical evidence for a major palaeochannel within the Obosum Group of the Volta Basin, Northern Region, Ghana

    Science.gov (United States)

    Jessell, Mark; Boamah, Kwame; Duodu, John Agyei; Ley-Cooper, Yusen

    2015-12-01

    We have identified a 230 km long palaeochannel cutting through the sediments of the Obosum Group within the Volta Basin, Ghana. The channel is visible in regional airborne magnetic data as a pair of parallel magnetic anomalies which we interpret to be lateral terrace placer deposits of magnetite or maghemite and show both meandering and braided geometries. The palaeochannel is also visible in the airborne radiometric data for part of its length, as well as in airborne electromagnetic data, where it is marked by a zone of low conductivity. The meanders have a wavelength of around 20 km and together with the 2 km spacing between magnetic anomalies, suggest a major palaeo-river system, of as yet unknown age, although based on published detrital zircon ages for the host sediments and geomorphological arguments it is probably between 509 ± 68 and 45 Ma, and is comparable in size to the modern-day Niger River. Given the known occurrences of alluvial gold and diamonds in Ghana, and the general prospectivity of meandering and braided rivers systems, we believe the region has exploration potential for a range of economically valuable minerals, and could also potentially host a shallow aquifer.

  3. Late Neogene stratigraphy and tectonic control on facies evolution in the Laguna Salada Basin, northern Baja California, Mexico

    Science.gov (United States)

    Martín-Barajas, A.; Vázquez-Hernández, S.; Carreño, A. L.; Helenes, J.; Suárez-Vidal, F.; Alvarez-Rosales, J.

    2001-10-01

    The Laguna Salada Basin (LSB) in northeastern Baja California records late-Neogene marine incursions in the Salton Trough and progradation of the Colorado River delta. Early subsidence and subsequent tectonic erosion are related to evolution of the Sierra El Mayor detachment fault during late Miocene time (geothermal exploratory well on the eastern margin of LSB. Interfingering fluvial-sandstone deposits and prograding alluvial fanglomerates with coarse debris-flow and rock-avalanche deposits crudely mark the onset of vertical slip along the Laguna Salada fault and rapid uplift of Sierra Cucapa and Sierra El Mayor. Up to 2 km of Quaternary alluvial-fan and lacustrine deposits accumulated along the eastern margin of LSB, whereas lower subsidence rates produced a thinner sedimentary wedge over a ramp-like crystalline basement along the western margin. In early Pleistocene time (˜2-1 Ma), the Laguna Salada became progressively isolated from the Colorado River delta complex, and the Salton Trough by activity on the Elsinore and Laguna Salada fault zones.

  4. Structural pattern of the Saïss basin and Tabular Middle Atlas in northern Morocco: Hydrological implications

    Science.gov (United States)

    Dauteuil, O.; Moreau, F.; Qarqori, K.

    2016-07-01

    The plain of Saïss is a fertile area of great agricultural production with major economic interests. Therefore, the improved knowledge about the water supply is imperative within a context of recurrent droughts and overexploitation of the groundwater. This plain is located in the Meknes-Fes basin and between two deformed domains: the Rif and Middle Atlas. The aquifers are fed by water coming from the Tabular Middle Atlas, for which the pathways are poorly constrained. This study provides new data to determine the water pathways based on a structural map produced from a novel analysis of SPOT images and a digital elevation model. This structural map reveals two fracture sets trending NE-SW and NW-SE. The first set is well known and corresponds to a main trend that controlled the tectonic and stratigraphic evolution of the study area. On the other hand, the NW-SE set was poorly described until now: it is both diffuse and widespread on the Tabular Middle Atlas. A comparison between the regional water flow trend, drainage pattern and structural map shows that the NW-SE fractures control the water flow from the Tabular Middle Atlas to the Saïss plain. A hydrological model is discussed where the water flow is confined onto Liassic carbonates and driven by NW-SE fractures. This study explains how a detailed structural mapping shows hydrology constraints.

  5. Detrital zircon and apatite fission track data in the Liaoxi basins: Implication to Meso-Cenozoic thermo-tectonic evolution of the northern margin of the North China Craton

    Indian Academy of Sciences (India)

    Yi Yan; Xiaoqiong Hu; Ge Lin; Weiliang Liu; Zhengjiang Song

    2010-08-01

    Detrital zircon and apatite fission track (ZFT and AFT) data of the sandstones collected from the Liaoxi basins served as a significant probe to study the Meso-Cenozoic thermo-tectonic reactivation events in the northern margin of the North China Craton. All sandstones show wide ZFT and AFT age spectrum and most of ZFT and AFT ages are younger than depositional age of respective host rocks, which suggest widespread track resetting of the host rocks in the Liaoxi basins after deposition. This hot geothermal status in the Liaoxi basins deduced from ZFT and AFT data is temporal consistent with the lithospheric evolution of the North China Craton, which implies that the lithosphere under the northern margin of the North China Craton underwent similar thermo-tectonic destruction process as the intracratonic Bohai Sea. The young ZFT peak age, which ranges from ∼50Ma to 20 Ma, to some extend, provides a temporal constraint on the time that lithosphere significantly thinned and following reverse of the Liaoxi basins and uplift of the eastern part of the Yan-Liao Orogenic Belt. Exhumation of 1.5–2 km can be estimated in the eastern part of the Yan-Liao Orogenic Belt since ∼30Ma to 10 Ma.

  6. Geology and geochemistry of the Reocín zinc-lead deposit, Basque-Cantabrian Basin, Northern Spain

    Science.gov (United States)

    Velasco, Francisco; Herrero, Jose Miguel; Yusta, Inaki; Alonso, Jose Antonio; Seebold, Ignacio; Leach, David

    2003-01-01

    fluids responsible for sulfide deposition and the infilling of karst cavities were broadly contemporaneous, indicating a post-Albian age. Vitrinite reflectance data are consistent with previously measured fluid inclusion temperatures and indicate temperatures of ore deposition that were less than 100??C. Carbon and oxygen isotopic data from samples of regional limestone, host-rock dolostone and ore-stage dolomite suggest an early hydrothermal alteration of limestone to dolostone. This initial dolomitization was followed by a second period of dolomite formation produced by the mixing of basinal metal-rich fluids with local modified seawater. Both dolomitization events occurred under similar conditions from fluids exhibiting characteristics of basinal brines. The ??34S values of sulfides are between -1.8 and +8.5 per mil, which is consistent with thermochemical sulfate reduction involving organic matter as the main source of reduced sulfur. Galena lead isotope compositions are among the most radiogenic values reported for Zn-Pb occurrences in Europe, and they are distinct from values reported for galena from other Basque-Cantabrian deposits. This suggests that a significant part of the lead was scavenged from the local underlying Asturian sediments. The stratigraphic and structural setting, timing of epigenetic mineralization, mineralogy, and isotopic geochemistry of sulfide and gangue minerals of the Reoci??n deposit are consistent with the features of most of Mississippi Valley-type ore deposits.

  7. Atmospheric nutrient inputs to the northern levantine basin from a long-term observation: sources and comparison with riverine inputs

    Directory of Open Access Journals (Sweden)

    M. Koçak

    2010-12-01

    Full Text Available Aerosol and rainwater samples have been collected at a rural site located on the coastline of the Eastern Mediterranean, Erdemli, Turkey between January 1999 and December 2007. Riverine sampling was carried out at five Rivers (Ceyhan, Seyhan, Göksu, Berdan and Lamas draining into the Northeastern Levantine Basin (NLB between March 2002 and July 2007. Samples have been analyzed for macronutrients of phosphate, silicate, nitrate and ammonium (PO43−, Sidiss, NO3 and NH4+. Phosphate and silicate in aerosol and rainwater showed higher and larger variations during the transitional period when air flows predominantly originate from North Africa and Middle East/Arabian Peninsula. Deficiency of alkaline material have been found to be the main reason of the acidic rain events whilst high pH values (>7 have been associated with high Sidiss concentrations due to sporadic dust events. In general, lowest nitrate and ammonium concentrations in aerosol and rainwater have been associated with air flow from the Mediterranean Sea. Comparison of atmospheric with riverine fluxes demonstrated that DIN and PO43− fluxes to NLB have been dominated by atmosphere (~90% and ~60% respectively whereas the input of Si was mainly derived from riverine runoff (~90%. N/P ratios in the atmospheric deposition (233; riverine discharge (28 revealed that NLB receives excessive amounts of DIN and this unbalanced P and N inputs may provoke even more phosphorus deficiency. Observed molar Si/N ratio suggested Si limitation relative to nitrogen might cause a switch from diatom dominated communities to non-siliceous populations particularly at coastal NLB.

  8. Algunos efectos de la precipitación del huracán Paulina en Acapulco, Guerrero

    OpenAIRE

    Lucía Guadalupe Matías Ramírez

    1998-01-01

    El huracán Pauiina se presentó del 6 al 10 de octubre de 1997, afectando las costas de los estados de Chiapas, Guerrero y Oaxaca. Se convirtió en huracán categoría 4 dentro de la escala Saffir-Simpson (eutremadamente peligroso), con vientos mayores de 210 kmlh y rachas de 240 kmih; esto produjo una precipitación mayor de 400 mm, durante cinco horas. en Acapulco, Guerrero, lo que originó impoitantes escunimientos. que provocaron derrumbes, inundaciones y la muerte de más de 120 person...

  9. Favorable exploration targets in northern Avat and northern Shuntuoguole areas, Tarim Basin%塔里木盆地阿瓦提北—顺托果勒北地区有利勘探方向分析

    Institute of Scientific and Technical Information of China (English)

    吕海涛; 耿锋; 毛庆言; 伍齐乔; 贺凯

    2012-01-01

    In the past years, few achievements in accordance with the scale of hydrocarbon generation depression have been obtained in petroleum explorations in Avat area of the Tarim Basin and the favorable exploration targets still remain exploring. Based on new exploration data and research progresses, it is discussed in this paper the petroleum geologic conditions in the northern Avat and the northern Shuntuoguole areas. Three petroleum systems have been identified according to petroleum system theory. As to the Cambrian-Ordovician petroleum system ( I) in Avat area, the most favorable exploration target is the middle-lower Ordovician karst-vuggy carbonate reservoir in the east of the study area. The traps formed in or before Yanshan period along big faults are less favorable. For the Triassic -Jurassic petroleum system ( \\) in Kuche area, the most favorable exploration targets include Paleogene-Cretaceous lithologic traps and various traps of unconformity fluctuation of early Himalayan epoch in the east of the area. Delta sandbody and lacustrine turbidite mass are favorable targets in the Triassic petroleum system (?) in Avat area.%塔里木盆地阿瓦提断陷长期以来未能取得与生烃坳陷相对应的油气勘探成果,勘探部署方向正处于探索之中.结合近期勘探取得的资料和新的研究进展,综合分析了阿瓦提北—顺托果勒北地区的石油地质条件,从含油气系统的角度,指出了阿瓦提寒武—奥陶系含油气系统(!)的最有利目标为研究区东部的中下奥陶统碳酸盐岩缝洞型储集体,其次为顺大断裂带分布并在燕山期及以前定型的圈闭;库车三叠—侏罗系含油气系统(!)的有利目标为研究区东部白垩系、古近系岩性圈闭和喜山早期不整合面上下的各类圈闭;阿瓦提三叠系含油气系统(?)有利方向为三叠系近烃源岩三角洲砂体、湖相浊积岩体.

  10. Methodology for Elaborating Regional Susceptibility Maps of Slope Instability: the State of Guerrero (mexico) Case Study

    Science.gov (United States)

    González Huesca, A. E.; Ferrés, D.; Domínguez-M, L.

    2013-05-01

    Numerous cases of different types of slope instability occur every year in the mountain areas of México. Sometimes these instabilities severely affect the exposed communities, roads and infrastructure, causing deaths and serious material damage, mainly in the states of Puebla, Veracruz, Oaxaca, Guerrero and Chiapas, at the central and south sectors of the country. The occurrence of the slope instability is the result of the combination of climatic, geologic, hydrologic, geomorphologic and anthropogenic factors. The National Center for Disaster Prevention (CENAPRED) is developing several projects in order to offer civil protection authorities of the Mexican states some methodologies to address the hazard assessment for different natural phenomena in a regional level. In this framework, during the past two years, a methodology was prepared to construct susceptibility maps for slope instability at regional (≤ 1:100 000) and national (≤ 1:1 000 000) levels. This research was addressed in accordance to the criteria established by the International Association of Engineering Geology, which is the highest international authority in this topic. The state of Guerrero has been taken as a pilot scheme to elaborate the susceptibility map for slope instability at a regional level. The major constraints considered in the methodology to calculate susceptibility are: a) the slope of the surface, b) the geology and c) the land use, which were integrated using a Geographic Information System (GIS). The arithmetic sum and weighting factors to obtain the final susceptibility map were based on the average values calculated in the individual study of several cases of slope instability occurred in the state in the past decade. For each case, the evaluation format proposed by CENAPRED in 2006 in the "Guía Básica para la elaboración de Atlas Estatales y Municipales de Peligros y Riesgos" to evaluate instabilities in a local level, was applied. The resulting susceptibility map shows

  11. Equinodermos asociados a formaciones arrecifales en Zihuatanejo y Acapulco, Guerrero, México

    OpenAIRE

    Zamorano, P.; Leyte_Morales, G.E.

    2009-01-01

    El conocimiento de los equinodermos de la región de Zihuatanejo y Acapulco, Guerrero, es escaso, y el existente refiere principalmente a listados taxonómicos. Con esos antecedentes, en este trabajo, se describión y caracterizó la comunidad de equinodermos asociada a arrecifes coralinos a partir de transectos de banda de 50 m de largo por 1 m d ancho. Durante 2004 se realizaron dos muestreos prospectivos (uno en época de lluvias y otro en época de secas). En total se registraron diez especies,...

  12. Hermenéutica de los derechos humanos en la obra de Ana Luisa Guerrero

    Directory of Open Access Journals (Sweden)

    Orlando Inocencio Aguirre Martínez

    2015-06-01

    Full Text Available La obra de Ana Luisa Guerrero se caracteriza por su abordaje filosófico-político sobre los derechos humanos y su aplicación. Su hermenéutica intercultural, dirigida, principalmente, a los derechos humanos de tercera generación, identifica el componente de la intersubjetividad que encamina hacia la construcción de un diálogo intercultural. Este componente permite, además, discutir sobre los fundamentos de los derechos humanos colocando las percepciones individuales y colectivas del paradigma.

  13. Boosting of Nonvolcanic Tremor by Regional Earthquakes 2011-2012 in Guerrero, Mexico

    Science.gov (United States)

    Real, J. A.; Kostoglodov, V.; Husker, A. L.; Payero, J. S.; G-GAP Research Team

    2013-05-01

    Sistematic observation of nonvolcanic tremor (NVT) in Guerrero, Mexico started in 2005 after the installation of MASE broadband seismic network. Since 2008 the new "G-GAP" network of 10 seismic mini-arrays provides the data for the NVT detailed studies together with the broadband stations of the Servicio Seimologogico Nacional (SSN). Most of the NVT recorded in the central Guerrero area are of so called ambient type, which in most cases are related with the occurrence of aseismic slow slip events (SSE). While the locations of NVT are estimated relatively well, their depths are not reliable but distributed close to the subduction plate interface. The ambient NVT activity increases periodically every 3-4 months and is strongly modulated by large SSE. Another type of tremor has been observed in Guerrero during and after several large teleseismic events, such as Mw=8.8, 2010 Maule, Chile earthquake. This NVT was triggered by the surface waves when they traveled across the tremor-generating area. Large teleseismic events may also activate a noticeable post-seismic NVT activity. In subduction zones, triggering of the NVT and its post-seismic activation by the regional and local earthquakes have not yet been observed. We tried to detect the NVT triggered or boosting of post-seismic tremor activity by two recent large earthquakes that occurred in Guerrero: December 11, 2011, Mw=6.5 Zumpango, and March 20, 2012, Mw=7.4 Ometepec. The first earthquake was of the intraplate type, with normal focal mechanism, at the depth of 58 km, and the second was the shallow interplate event of the thrust type, at the depth of ~15 km. It is technically difficult to separate the NVT signal in its characteristic 1-10 Hz frequency range from the high frequency input from the regional earthquake. The Zumpango event, which is located closer to the NVT area, produced a noticeable boosting of post-seismic NVT activity to the North of its epicenter. Meanwhile the larger magnitude Ometepec

  14. Registros adicionales de felinos del estado de Guerrero, México

    OpenAIRE

    José Alberto Almazán-Catalán; Cornelio Sánchez-Hernández; Fernando Ruíz-Gutiérrez; María de Lourdes Romero-Almaraz; Alejandro Taboada-Salgado; Elizabeth Beltrán-Sánchez; Leobardo Sánchez-Vázquez

    2013-01-01

    Se amplía la información sobre distribución, hábitat y medidas somáticas y craneales de las 6 especies de felinos que se distribuyen en nuestro país y que se encuentran en Guerrero. La presencia de estas especies se obtuvo a través de métodos directos y registros indirectos. Lynx rufus está representado por la piel y el cráneo de un joven y es el segundo registro para el estado; mientras que Puma concolor, Puma yagouaroundi, Leopardus pardalis, Leopardus wiedii y Panthera onca incrementan su ...

  15. A CORPORATE STRATEGY FOR THE PREVENTION OF MATERNAL DEATH IN THE STATE OF GUERRERO, MEXICO

    Directory of Open Access Journals (Sweden)

    Aurelia Flores-Hernández

    2012-01-01

    Full Text Available This work reflects on the actions taken to preventmaternal mortality at local level for two agents:Guerrero government trough Women Secretary and theactive participation of four social organizationscompromised to a worthy, sure and pleasantmotherhood. It is interested to show the approaches andexpectations of a program executed from 2005 to 2009.Particularly, it’s demonstrated that the alliance betweenSEMUJER and social organizations contributes togenerate specific actions to offset the possibility ofdying for risks associated to motherhood, though theseare still insufficient. The work is qualitative, and itsanalysis supports the gender relations.

  16. Estudio florístico de Ficus (Moraceae) en el estado de Guerrero, México

    OpenAIRE

    Carlos Alberto Durán-Ramírez; Rosa María Fonseca-Juárez; Guillermo Ibarra-Manríquez

    2010-01-01

    Con base en salidas al campo y la revisión de ejemplares de herbario, se registran 13 especies de Ficus (Moraceae) en el estado de Guerrero, 4 pertenecen al subgénero Pharmacosycea (F.insípida, F. lapathifolia, F. maxima y F. yoponensis) y 9 al subgénero Urostigma (F. citrifolia, F. cotinifolia, F. crocata, F. membranacea, F. obtusifolia, F. pertusa, F. petiolaris, F. pringlei y F. velutina), al cual se añade un posible registro de F. aurea. Se incluye una clave para su identificación y se pr...

  17. Study of hydro-saline characteristics of soils a palm grove in basin of Ouargla (Northern Algerian Sahara)

    Science.gov (United States)

    Rezagui, D.; Bouhoun, M. Dabbi; Boutoutaou, D.; Djaghoubi, A.

    2016-07-01

    Saharan soils are often faced with several problems of development, taking account the hydro-edaphic constraints, mainly of hydric types by water table, mechanical by gypso-calcareous crusts and saline by irrigation waters and upwelling of water table. Our work consists in doing a soil characterization of a palm grove in Ouargla in order to study the constraints hydro-halomorphes. The results show that irrigation water by two plies of Senonian and Mioplcène had a high salinity with a value of 2.83 and 5.10 dS.m-1 respectively. The conduct of irrigation is traditional random of submersion type. The palm grove has a poor drainage with a level of water table 156.67±15.71 cm and salinity of 31.37±34.04 dS.m-1. The drains are open type and their maintenance is not regular. This situation of management of irrigation-drainage promotes the upwelling of water table and the waterlogging in soils. The study of soil profiles shows the existence of mechanical obstruction of gypso-calcareous crusts which limit the entrenchment of the date palms and the leaching of salts. Soil salinity is excessive in profiles with a range of 8.98 ± 4.58 dS.m-1. This accumulation of salts is due to the dynamic ascending and descending of salts respectively under the effect of upwelling of water table and leaching by irrigation. The salinization, the upwelling of water table and the presence of gypso-calcareous crusts recorded in Ouargla testify to a degradation hydro-halomorphe and mechanic of soil which constitute the major constraints in the management of system irrigation-drainage and sustainable agricultural development of the palm groves of the basin of Ouargla. Some hydro-agricultural planning are necessary to apply in the oasis to improve the hydro-mechanical properties of soils in order to reduce their degradation.

  18. Morphologies and depositional/erosional controls on evolution of Pliocene-Pleistocene carbonate platforms: Northern Carnarvon Basin, Northwest Shelf of Australia

    Science.gov (United States)

    Goktas, P.; Austin, J. A.; Fulthorpe, C. S.; Gallagher, S. J.

    2016-08-01

    The detailed morphologies, evolution and termination of latest Neogene tropical carbonate platforms in the Northern Carnarvon Basin (NCB), on the passive margin of the Northwest Shelf (NWS) of Australia, defined based upon mapping using 3D seismic images, reveal the history of local/regional oceanographic processes, fluctuations in relative sea-level and changing climate. Cool-water carbonate deposition, dominant during the early-middle Miocene, was followed by a siliciclastic influx, which prograded across the NWS beginning in the late-middle Miocene, during a period of long-term global sea-level fall. The resulting prograding clinoform sets, interpreted as delta lobes, created relict topographic highs following Pliocene termination of the siliciclastic influx. These highs constituted multiple favorable shallow-water environments for subsequent photozoan carbonate production. Resultant platform carbonate development, in addition to being a response to cessation of siliciclastic influx and the existence of suitable shallow-water substrate, was also influenced by development of the warm-water Leeuwin Current (LC), flowing southwestward along this margin. Four flat-topped platforms are mapped; each platform top is a sequence boundary defined by reflection onlap above and truncation below. Successive platforms migrated southwestward through time, along margin strike. All platforms exhibit predominantly progradational seismic geometries. Mapped tops are ≥10 km wide. Seismic evidence of karst on three of four platform tops, e.g., v-shaped troughs up to 50 m deep and ~1 km wide, and broader basins with areas up to 20 km2, suggests episodic subaerial exposure that may have contributed to platform demise. Platform 4, the most recent, is unique in having interpreted biohermal build-ups superimposed on the progradational platform base. The base of these interpreted patch reefs now lies at a water depth of ~153 m; therefore, we suggest that these reefs developed post

  19. Exhumation history of the Northern Andes from the Cenozoic syn-tectonic sedimentary fill of the Middle Magdalena Valley Basin, Colombia

    Science.gov (United States)

    Moreno, C. J.; Caballero, V. M.; Horton, B. K.; Mora, A.

    2009-12-01

    The Central Cordillera and the Eastern Cordillera of the northern Andes form the western and eastern flanks of the Colombian Middle Magdalena Valley Basin, respectively. Previous estimates of the timing of onset of exhumation of the two cordilleras vary, and although some recent studies have been in agreement, more work is needed to develop a clear picture. The spatial and chronological distribution of deformation has direct implications for the shortening history of the greater South American Andean margin, as well as for improving predictions of the rapid, lateral facies changes associated with the varying nearby sediment sources. Field-based analyses of the basin fill using paleocurrent measurements of trough-cross-beds, clast imbrication and flute casts, not only provide new insights into the tectonic history, but directly complement recent detrital zircon U-Pb work completed in the MMVB. Between the lower and upper Paleocene strata, the paleocurrent direction shifts from northward to eastward, indicating that uplift of the Central Cordillera was underway by the mid-Paleocene and consistent with the shift from a cratonic to Central Cordilleran sediment source observed in the detrital zircon record. This paleocurrent shift occurs coevally with a shift from delta to fluvial facies. An eastward paleoflow in upper Eocene through lowest Oligocene strata indicate a continuing influence of the Central Cordillera. Paleocurrent directions in the lower Oligocene deposits are highly variable, and, beginning in the middle Oligocene strata, show a switch to a dominantly westward orientation that continues through the Neogene. As the orientation changes, deposits show an increase in energy from muddy, meandering river deposits, to coarser, braided channel facies. We attribute this switch, from eastward to westward paleocurrent orientations, to the onset of exhumation of the Eastern Cordillera. The results of a current, detailed sandstone petrographic study combined with

  20. Geologic controls on transgressive-regressive cycles in the upper Pictured Cliffs sandstone and coal geometry in the lower Fruitland Formation, Northern San Juan Basin, New Mexico and Colorado

    Energy Technology Data Exchange (ETDEWEB)

    Ambrose, W.A.; Ayers, W.B. [University of Texas, Austin, TX (United States)

    2007-08-15

    Three upper Pictured Cliffs Sandstone tongues in the northern part of the San Juan Basin record high-frequency transgressive episodes during the Late Cretaceous and are inferred to have been caused by eustatic sea level rise coincident with differential subsidence. Outcrop and subsurface studies show that each tongue is an amalgamated barrier strand-plain unit up to 100 ft (30 m) thick. Upper Pictured Cliffs barrier strand-plain sandstones underlie and bound thickest Fruitland coal seams on the seaward side. Controls on Fruitland coal-seam thickness and continuity are a function of local facies distribution in a coastal-plain setting, shoreline positions related to transgressive-regressive cycles, and basin subsidence. During periods of relative sea level rise, the Pictured Cliffs shoreline was temporarily stabilized, allowing thick, coastal-plain peats to accumulate. Although some coal seams in the lower Fruitland tongue override abandoned Pictured Cliffs shoreline deposits, many pinch out against them. Differences in the degree of continuity of these coal seams relative to coeval shoreline sandstones are attributed to either differential subsidence in the northern part of the basin, multiple episodes of sea level rise, local variations in accommodation and progradation, stabilization of the shoreline by aggrading peat deposits, or a combination of these factors. Fruitland coalbed methane resources and productivity are partly controlled by coal-seam thickness; other important factors include thermal maturity, fracturing, and overpressuring. The dominant production trend occurs in the northern part of the basin and is oriented northwestward, coinciding with the greatest Fruitland net coal thickness.

  1. THE COMMUNITY SOCIAL CAPITAL, A STRATEGY AGAINST POVERTY IN INDIGENOUS PEOPLES OF THE STATE OF GUERRERO

    Directory of Open Access Journals (Sweden)

    Adrián González-Romo

    2014-01-01

    Full Text Available Indigenous peoples of Guerrero show different tradeoffs in their ways of dealing with such adverse reality that afflicts them , first struggling to maintain the traditions and customs , using their customary community practices to maintain unity and confront the inhumane living conditions through what has been called community organization , considered part of the concept of social capital and the other institutions that do their thing trying to find solutions to this problem , however the methods collide and sometimes opposed. The community Assembly, the safety, the slaughter, the tequio are part of some of these practices, which despite maintained indigenous families living conditions have not improved substantially and increasingly is more noticeable migration in search of employment, in different scenarios. The majority indigenous population inhabiting the Amuzgos of Guerrero State, Mixtecos, Tlapanecos and Nahuas, looking each one with its own peculiarities, survive. Poverty, marginalization and physical-geographical conditions determine the circle of the dire living conditions of these indigenous people. As happened in 2013 with the tropical storm "Manuel", where we witnessed the way how adverse natural phenomena stick stronger to weaker.

  2. Anthropogenically-Induced Superficial Seismic Activity Modulated By Slow-Slip Events in Guerrero, Mexico

    Science.gov (United States)

    Frank, W.; Shapiro, N.; Husker, A. L.; Kostoglodov, V.; Campillo, M.

    2014-12-01

    We use the data of the MASE seismic experiment operated during 2.5 years in Guerrero, Mexico to create a large catalog of seismic multiplets. This catalog is dominated by families of Low-Frequency Earthquakes (LFE) occurring in vicinity of the main subduction interface. In addition to more than one thousand LFE families, we detected nine repeating seismic event families that are located in the upper crust and are anthropogenically induced (AI) by mining blasts. Analysis of the recurrence of these AI events in time shows that their activity significantly increases during the strong Slow-Slip Event (SSE) in 2006. Modeled static stress perturbations induced by the SSE at the surface are ~5 kPa that is on the same order of magnitude as dynamic stress perturbations observed to trigger other low stress drop phenomena, such as tectonic tremor. We propose therefore that strong SSEs in Guerrero impose an extensional regime throughout the continental crust, modifying the stress field near the surface and increasing AI activity. This modulation of the recurrence of the crustal seismic events by the SSE-induced stress might be related to another recent observation: the SSE-induced reduction of seismic velocities linked to nonlinear elastic effects caused by opening of cracks (Rivet et al., 2011, 2014).

  3. On Intensive Late Holocene Iron Mining and Production in the Northern Congo Basin and the Environmental Consequences Associated with Metallurgy in Central Africa.

    Science.gov (United States)

    Lupo, Karen D; Schmitt, Dave N; Kiahtipes, Christopher A; Ndanga, Jean-Paul; Young, D Craig; Simiti, Bernard

    2015-01-01

    An ongoing question in paleoenvironmental reconstructions of the central African rainforest concerns the role that prehistoric metallurgy played in shaping forest vegetation. Here we report evidence of intensive iron-ore mining and smelting in forested regions of the northern Congo Basin dating to the late Holocene. Volumetric estimates on extracted iron-ore and associated slag mounds from prehistoric sites in the southern Central African Republic suggest large-scale iron production on par with other archaeological and historically-known iron fabrication areas. These data document the first evidence of intensive iron mining and production spanning approximately 90 years prior to colonial occupation (circa AD 1889) and during an interval of time that is poorly represented in the archaeological record. Additional site areas pre-dating these remains by 3-4 centuries reflect an earlier period of iron production on a smaller scale. Microbotanical evidence from a sediment core collected from an adjacent riparian trap shows a reduction in shade-demanding trees in concert with an increase in light-demanding species spanning the time interval associated with iron intensification. This shift occurs during the same time interval when many portions of the Central African witnessed forest transgressions associated with a return to moister and more humid conditions beginning 500-100 years ago. Although data presented here do not demonstrate that iron smelting activities caused widespread vegetation change in Central Africa, we argue that intense mining and smelting can have localized and potentially regional impacts on vegetation communities. These data further demonstrate the high value of pairing archeological and paleoenvironmental analyses to reconstruct regional-scale forest histories.

  4. Biodegraded Oil and Its High Molecular Weight (C35+) n-alkanes in the Qianmiqiao Region in the Bohai Bay Basin, Northern China

    Institute of Scientific and Technical Information of China (English)

    WANG Tieguan; ZHU Dan; LU Hong; ZHANG Zhihuan; YANG Chiyin

    2004-01-01

    With a production of 208.2 m3/d, heavy oil was produced by drill stem test (DST) from three shallow reservoirs in Sand Group Nos. Ⅰ and Ⅲ of the Neogene Guantao Formation (Ng1 and NgⅢ) and the Eogene Dongying Formation (Ed) in an exploratory well Ban-14-1 within the Qianmiqiao region, Bohai Bay Basin, northern China. Based on the GC and GC-MS data of theNgⅠand NgⅢheavy oil samples, all n-alkanes and most isoprenoid hydrocarbons are lost and the GC baseline appears as an evident "hump", implying a large quantity of unresolved complex mixture (UCM),which typically revealed a result of heavy biodegradation. However, there still is a complete series of C14-C73 n-alkanes in the high-temperature gas chromatograms (HTGC) of the heavy oil, among which, the abundance of C30- n-alkanes are drastically reduced. The C35-C55 high molecular weight (HMW) n-alkanes are at high abundance and show a normal distribution pattern with major peak at C43 and an obvious odd-carbon-number predominance with CPI37-55 and OEP45-49values of 1.17 and 1.16-1.20, respectively. According to GC-MS analysis, the heavy oil is characterized by dual source inputs of aquatic microbes and terrestrial higher plants. Various steranes and tricyclic terpanes indicate an algal origin, and hopane-type triterpanes, C24tetracyclic terpane and drimane series show the bacterial contribution. With the odd-carbonnumber preference, HMW n-alkanes provide significant information not only on higher plant source input and immaturity,but also on the strong resistibility to biodegradation.

  5. Environmental history of the dry forest biome of Guerrero, Mexico, and human impact during the last c. 2700 years

    NARCIS (Netherlands)

    J.C. Berrio; H. Hooghiemstra; B. van Geel; B. Ludlow-Wiegers

    2006-01-01

    Two lake sediment cores from Madre del Sur mountain range, Guerrero State, west-central Mexico were studied to examine the past dynamics of the dry forest biome. Pollen, spores of coprophilous fungi, cyanobacteria and lithological changes are presented. The 390-cm Tixtla core (17°30′N, 99°24′W, 1400

  6. Low frequency amplification in deep alluvial basins: an example in the Po Plain (Northern Italy) and consequences for site specific SHA

    Science.gov (United States)

    Mascandola, Claudia; Massa, Marco; Barani, Simone; Lovati, Sara; Santulin, Marco

    2016-04-01

    This work deals with the problem of long period seismic site amplification that potentially might involve large and deep alluvial basins in case of strong earthquakes. In particular, it is here presented a case study in the Po Plain (Northern Italy), one of the most extended and deep sedimentary basin worldwide. Even if the studied area shows a low annul seismicity rate with rare strong events (Mw>6.0) and it is characterized by low to medium seismic hazard conditions, the seismic risk is significant for the high density of civil and strategic infrastructures (i.e. high degree of exposition) and the unfavourable geological conditions. The aim of this work is to provide general considerations about the seismic site response of the Po Plain, with particular attention on deep discontinuities (i.e. geological bedrock), in terms of potential low frequency amplification and their incidence on the PSHA. The current results were obtained through active and passive geophysical investigations performed near Castelleone, a site where a seismic station, which is part of the INGV (National Institute for Geophysics and Volcanology) Seismic National Network, is installed from 2009. In particular, the active analyses consisted in a MASW and a refraction survey, whereas the passive ones consisted in seismic ambient noise acquisitions with single stations and arrays of increasing aperture. The results in terms of noise HVSR indicate two main peaks, the first around 0.17 Hz and the second, as already stated in the recent literature, around 0.7 Hz. In order to correlate the amplified frequencies with the geological discontinuities, the array acquisitions were processed to obtain a shear waves velocity profile, computed with a joint inversion, considering the experimental dispersion curves and the HVSR results. The obtained velocity profile shows two main discontinuities: the shallower at ~165 m of depth, which can be correlated to the seismic bedrock (i.e. Vs > 800 m/) and the deeper

  7. Summary of surface-water-quality data collected for the Northern Rockies Intermontane Basins National Water-Quality Assessment Program in the Clark Fork-Pend Oreille and Spokane River basins, Montana, Idaho, and Washington, water years 1999-2001

    Science.gov (United States)

    Beckwith, Michael A.

    2003-01-01

    Water-quality samples were collected at 10 sites in the Clark Fork-Pend Oreille and Spokane River Basins in water years 1999 – 2001 as part of the Northern Rockies Intermontane Basins (NROK) National Water-Quality Assessment (NAWQA) Program. Sampling sites were located in varied environments ranging from small streams and rivers in forested, mountainous headwater areas to large rivers draining diverse landscapes. Two sampling sites were located immediately downstream from the large lakes; five sites were located downstream from large-scale historical mining and oreprocessing areas, which are now the two largest “Superfund” (environmental remediation) sites in the Nation. Samples were collected during a wide range of streamflow conditions, more frequently during increasing and high streamflow and less frequently during receding and base-flow conditions. Sample analyses emphasized major ions, nutrients, and selected trace elements. Streamflow during the study ranged from more than 130 percent of the long-term average in 1999 at some sites to 40 percent of the long-term average in 2001. River and stream water in the study area exhibited small values for specific conductance, hardness, alkalinity, and dissolved solids. Dissolved oxygen concentrations in almost all samples were near saturation. Median total nitrogen and total phosphorus concentrations in samples from most sites were smaller than median concentrations reported for many national programs and other NAWQA Program study areas. The only exceptions were two sites downstream from large wastewater-treatment facilities, where median concentrations of total nitrogen exceeded the national median. Maximum concentrations of total phosphorus in samples from six sites exceeded the 0.1 milligram per liter threshold recommended for limiting nuisance aquatic growth. Concentrations of arsenic, cadmium, copper, lead, mercury, and zinc were largest in samples from sites downstream from historical mining and ore

  8. Estudio florístico de Ficus (Moraceae en el estado de Guerrero, México Floristic study of Ficus (Moraceae in the state of Guerrero, Mexico

    Directory of Open Access Journals (Sweden)

    Carlos Alberto Durán-Ramírez

    2010-08-01

    Full Text Available Con base en salidas al campo y la revisión de ejemplares de herbario, se registran 13 especies de Ficus (Moraceae en el estado de Guerrero, 4 pertenecen al subgénero Pharmacosycea (F.insípida, F. lapathifolia, F. maxima y F. yoponensis y 9 al subgénero Urostigma (F. citrifolia, F. cotinifolia, F. crocata, F. membranacea, F. obtusifolia, F. pertusa, F. petiolaris, F. pringlei y F. velutina, al cual se añade un posible registro de F. aurea. Se incluye una clave para su identificación y se proporcionan descripciones, mapas de distribución, datos del hábitat y fenología de las especies, y se ilustran 6 de éstas. El bosque de galería y el bosque tropical caducifolio destacan por su riqueza de especies (8. Ficus lapathifolia restringe su distribución al bosque mesófilo de montaña y F. pringlei al bosque tropical caducifolio. Chilpancingo de los Bravo y Atoyac de Álvarez fueron los municipios con mayor cantidad de especies, con 11 y 9 especies, respectivamente. Por primera vez se registran para el estado: F. crocata, F. lapathifolia, F. membranacea, F. pringlei y F. yoponensis.Based on herbarium specimens and on field explorations, 14 native species of Ficus (Moraceae were recognized for Guerrero, Mexico. Four species are included in subgenus Pharmacosycea (Ficus insipida, F. lapathifolia, F. maxima and F. yoponensis and 9 in subgenus Urostigma (F. citrifolia, F. cotinifolia, F. crocata, F. membranacea, F. obtusifolia, F. pertusa, F. petiolaris, F. pringlei and F. velutina, including a possible record of F. aurea. A key, descriptions, distribution maps, and phenology data of species are provided, and 6 of them are ilustrated. Riparian forest and tropical deciduous forest were the vegetation communities with the highest number of species (8. Ficus lapathifolia was restricted to cloud forest whereas F. pringlei shows the same condition in the tropical deciduous forest. The municipalities of Chilpancingo de los Bravo and Atoyac de Alvarez

  9. The 2015 Sandpoint, Idaho, Earthquake Sequence: A Constraint on Basin-and-Range Style Extension on the Western Portion of the Lewis and Clark Fault Zone, Northern Rockies, U.S.A.

    Science.gov (United States)

    Kobayashi, D.; Sprenke, K. F.; Stickney, M.; Phillips, W. M.

    2015-12-01

    The Lewis and Clark Fault Zone (LCFZ) is a megashear that extends WNW about 800 km across the northern Rockies. In Montana, the LCFZ is associated with recurrent seismicity including multiple M6 events near Helena. This raises the question of whether similar damaging earthquakes might occur along the western part of the LCFZ in northern Idaho and eastern Washington. Background seismicity is low in this region. However, three widely felt earthquakes (~M4) representing the first significant seismicity since 1942 in the Idaho Panhandle occurred near Sandpoint on April 24th 2015. Fault plane solutions of these events, along with recent GPS velocity results and a re-analysis of the 2001 swarm of Mrelict structures in the western LCFZ causes reverse mechanisms and contractional strain fundamentally different from the basin-and-range style extension along the eastern LCFZ in Montana. The M6 Montana events involved dextral strike-slip motion on the steeply-dipping WNW trending faults. Similar faults occur close to population centers in northern Idaho and eastern Washington. However, the stress field revealed by our study does not favor such fault motion in the western LCFZ. Our results constrain the western extent of the basin-and-range style extension along the LCFZ.

  10. 新疆准噶尔盆地北缘中中新世早期的原圆齿鼠(Promylagaulinae,Mylagaulidae)%Mylagaulids (Mammalia: Rodentia) from the early Middle Miocene of northern Junggar Basin

    Institute of Scientific and Technical Information of China (English)

    吴文裕; 倪喜军; 叶捷; 孟津; 毕顺东

    2013-01-01

    Application of CT (computed tomography) scanning technology to the study of tooth morphology of mylagaulids makes better understanding the tooth structure of high-crowned mylagaulids. Two genera and species from the early Middle Miocene Halamagai Formation innorthern Junggar Basin of Xinjiang are recognized: Tschalimys ckhikvadzei Shevyreva, 1971,the senior synonym of Sinomylagaulus halamagaiensis Wu, 1988 and Simpligaulus yangi gen.et sp. nov. Both taxa undoubtedly belong to the subfamily Promylagaulinae. The integrated lithological, paleontological and paleomagnetic studies on sediments of the Late Oligocene through Late Miocene in the northern Junggar Basin of Xinjiang demonstrate that Halamagai Formation is fluvial-lacustrine sediments formed during the time coincident to the Mid-Miocene Climatic Optimum. T. ckhikvadzei and S. yangi probably inhabit the humid and warm regions with forests and densely vegetated thickets as the living mountain beaver Aplodontia rufa does. Thesemylagaulids are probably immigrants or the descendants of the immigrants from west North America.

  11. Actual Evapotranspiration in the Al-Khazir Gomal Basin (Northern Iraq) Using the Surface Energy Balance Algorithm for Land (SEBAL) and Water Balance

    OpenAIRE

    Hussein Jassas; Wael Kanoua; Broder Merkel

    2015-01-01

    Increasing dependence on groundwater requires a detailed determination of the different outputs and inputs of a basin for better water management. Determination of spatial and temporal actual evapotranspiration (ETa), in this regard, is of vital importance as there is significant water loss from drainage basins. This research paper uses the Surface Energy Balance Algorithm for Land (SEBAL), as well as the water balance, to estimate the spatial and temporal ETa in the Al-Khazir Gomal Basin, No...

  12. Integrated stratigraphy of the Smirra Coring: a new reference sedimentary record for the early Paleogene from the Umbria-Marche Basin (Northern Apennines, Italy)

    Science.gov (United States)

    Turtù, Antonio; Lauretano, Vittoria; Catanzariti, Rita; Galeotti, Simone; Lanci, Luca; Moretti, Matteo; Lourens, Lucas J.

    2016-04-01

    The early Paleogene represents a critical time interval in Earth's history characterized by prolonged greenhouse conditions, culminating in a series of extreme global warming events (i.e. hyperthermals), as well as large uncertainties in the Geological Time Scale. Therefore new, high-resolution, geological records are crucial in providing novel constraints on these topics. The Paleogene Umbria-Marche sections of the Northern Apennines (Italy) have shown to be suitable for integrated stratigraphy allowing regional-to-global correlations and environmental reconstructions across this time interval. Among several well-known sections, a new sedimentary record is provided by the Smirra Coring, which recovered an undisturbed sequence of rocks (~120 m from 4 overlapping holes) spanning the upper Scaglia Fms. (early Paleocene - middle Eocene) of the Umbria-Marche pelagic succession. Here we present a new, high-resolution, integrated stratigraphic framework (magnetostratigraphy, calcareous nannofossil biostratigraphy, physical properties, calibrated XRF core scanning and cyclostratigraphy) of the ~93 m composite section drilled in Smirra Holes 1 and 2. The succession extends almost continuously, with modest tectonic disturbance affecting its lowermost part with minor faulting. The resulting magnetic stratigraphy defines a succession of normal and reversed polarity magnetozones. The correlation of the paleomagnetic polarity sequence with the latest Geomagnetic Polarity Timescales (GPTSs; e.g. CK95, GTS 2004 and 2012), also constrained through nannofossil biostratigraphy, shows that the section spans the late Paleocene - middle Eocene from chrons C21n (~46 Ma) to C26r (~60 Ma). The overall sedimentation rates computed at Smirra are fully comparable with those from coeval sections from the Umbria-Marche Basin, ranging from ~10 m/Ma, between chrons C21n and C22n, to ~6 m/Ma, between chrons C22r and the base of the section. However, the sedimentation rates vary considerably

  13. Development of a System-Wide Predator Control Program: Stepwise Implementation of a Predation Index, Predator Control Fisheries, and Evaluation Plan in the Columbia River Basin; Northern Pikeminnow Management Program, 2001 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Porter, Russell G.; Winther, Eric C.; Fox, Lyle G.

    2003-03-01

    This report presents results for year eleven in a basin-wide program to harvest northern pikeminnow (Ptychocheilus oregonensis). This program was started in an effort to reduce predation by northern pikeminnow on juvenile salmonids during their emigration from natal streams to the ocean. Earlier work in the Columbia River Basin suggested predation by northern pikeminnow on juvenile salmonids might account for most of the 10-20% mortality juvenile salmonids experience in each of eight Columbia River and Snake River reservoirs. Modeling simulations based on work in John Day Reservoir from 1982 through 1988 indicated that, if predator-size northern pikeminnow were exploited at a 10-20% rate, the resulting restructuring of their population could reduce their predation on juvenile salmonids by 50%. To test this hypothesis, we implemented a sport-reward angling fishery and a commercial longline fishery in the John Day Pool in 1990. We also conducted an angling fishery in areas inaccessible to the public at four dams on the mainstem Columbia River and at Ice Harbor Dam on the Snake River. Based on the success of these limited efforts, we implemented three test fisheries on a system-wide scale in 1991--a tribal longline fishery above Bonneville Dam, a sport-reward fishery, and a dam-angling fishery. Low catch of target fish and high cost of implementation resulted in discontinuation of the tribal longline fishery. However, the sport-reward and dam-angling fisheries were continued in 1992 and 1993. In 1992, we investigated the feasibility of implementing a commercial longline fishery in the Columbia River below Bonneville Dam and found that implementation of this fishery was also infeasible.

  14. Trypanosoma cruzi infection in the Mexican state of Guerrero: a seroepidemiological (ELISA) survey of 20 communities.

    Science.gov (United States)

    Andersson, N; Morales, A; Nava, E; Martinez, E; Rodriguez, I; Young, P; Howard, M K; Miles, M A

    1990-10-01

    The enzyme linked immunosorbent assay (ELISA) was used to analyse 4372 blood samples from residents of 978 households in 20 representative communities in the Mexican state of Guerrero. Seventy-five individuals had very high titres of antibodies against Trypanosoma cruzi. Samples with intermediate optical density values, despite overlapping values with several control positives on a single-well test, did not sustain their positivity at high dilutions. 'Intermediate positives' had a different distribution among the 20 communities to samples sustaining reactivity at high dilutions, indicating possible cross-reactivity with another infectious agent. The finding of seropositive children under the age of 10 years in the Costa Chica, Acapulco and the Tierra Caliente regions, with family clustering of putative cases, indicates that recent transmission must be considered. Very few people interviewed in the 20 communities knew the triatomine bug could transmit a disease.

  15. A new species of Rhadinella (Serpentes: Colubridae) from the Sierra Madre del Sur of Guerrero, Mexico.

    Science.gov (United States)

    Campillo, Gustavo; Dávila-Galavíz, Luis Fernando; Flores-Villela, Oscar; Campbell, Jonathan A

    2016-01-01

    We describe a new species of Rhadinella from the Sierra Madre del Sur of Guerrero, Mexico, a region where the genus was previously unknown. This diminutive species is a member of a group of snakes previously allocated in the Rhadinaea godmani group, and more recently transferred to the genus Rhadinella. These snakes may have conspicuous dark longitudinal striping on a pale brown to orange background or may have dark brown to blackish dorsal ground coloration, which mostly or completely obfuscates a pattern of longitudinal striping. The new species is mostly dark with barely discernible slightly paler or darker striping (depending on how striping is interpreted). The closest relative of the new species, on the basis of morphological similarities and biogeography, appears to be Rhadinella donaji which occurs to the east in the Sierra Madre del Sur of Oaxaca about 275 km from the type-locality of the new species.

  16. Thermal structure, coupling and metamorphism in the Mexican subduction zone beneath Guerrero

    Science.gov (United States)

    Manea, V. C.; Manea, M.; Kostoglodov, V.; Currie, C. A.; Sewell, G.

    2004-08-01

    Temperature is one of the most important factors that controls the extent and location of the seismogenic coupled and transition, partially coupled segments of the subduction interplate fault. The width of the coupled fault inferred from the continuous GPS observations for the steady interseismic period and the transient width of the last slow aseismic slip event (Mw~ 7.5) that occurred in the Guerrero subduction zone in 2001-2002 extends up to 180-220 km from the trench. Previous thermal models do not consider this extremely wide coupled interface in Guerrero subduction zone that is characterized by shallow subhorizontal plate contact. In this study, a finite element model is applied to examine the temperature constraints on the width of the coupled area. The numerical scheme solves a system of 2-D Stokes equation and 2-D steady-state heat transfer equations. The updip limit of the coupling zone is taken between 100 and 150 °C, while the downdip limit is accepted at 450 °C as the transition from partial coupling to stable sliding. From the entire coupled zone, the seismogenic zone extends only up to ~82 km from the trench (inferred from the rupture width of large subduction thrust earthquakes), corresponding to the 250 °C isotherm. Only a small amount of frictional heating is needed to fit the intersection of the 450 °C isotherm and the subducting plate surface at 180-205 km from the trench. The calculated geotherms in the subducting slab and the phase diagram for MORB are used to estimate the metamorphic sequences within the oceanic subducting crust. A certain correlation exists between the metamorphic sequences and the variation of the coupling along the interplate fault.

  17. Impact of the northern South America Plate boundary evolution upon petroliferous basins%南美板块北部边界作用对其含油气盆地的影响

    Institute of Scientific and Technical Information of China (English)

    程小岛; 李江海; 高危言

    2013-01-01

    This article correlated the evolution history of the northern South America Plate and its typical petroliferous basins(Maracaibo Basin and East Venezuela Basin).In the early of evolution, the northern South America Plate was in the passive margin stage when quality marine source rocks were deposited in these petroliferous basins.In the late of evolution, the east-to-west oblique subduction of the Caribbean Plate under the South American Plate resulted in the sequential tectonic evolution of the petroliferous basins in northern South America, i.e.tectonic evolution of the basin in the west was prior to that in the east.Correspondingly, the generation, migration and accumulation of hydrocarbons obeyed similar order to that of basins.The subduction resulted in the formation of many clastic-filled wedges, which are wonderful reservoirs.Hydrocarbons migrated from north to south along compression stress direction and faults and were eventually preserved within structural traps.Moreover, the oblique character of subduction brought certain strike-slip properties to the thrust faults.Many strike-slip faults were developed and imposed little late damages to the accumulation of oil and gas, leading to better preserve conditions for the oil and gas in northern South America.%对比分析了南美板块北部演化史及其典型含油气盆地——马拉开波盆地和东委内瑞拉盆地的发育史,认为当南美板块北部早期处于被动陆缘发育阶段时,其含油气盆地沉积了优质的海相烃源岩;后期加勒比板块相对南美板块自西向东斜向俯中,使南美北部盆地不同阶段演化时间具有先后顺序,即西部盆地构造演化先于东部盆地,盆地油气的成熟、运移和成藏也相应地具有一定的先后次序性.俯冲带来大量碎屑充填的前陆楔状体,为油气提供了良好的储层,油气沿挤压应力方向和俯冲产生的多种断层自北向南运移,并最终保存在构造圈闭中.此外,加勒

  18. Development of a System-Wide Predator Control Program: Stepwise Implementation of a Predation Index, Predator Control Fisheries, and Evaluation Plan in the Columbia River Basin; Northern Pikeminnow Management Program, 2002 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Porter, Russell G.; Winther, Eric C.; Fox, Lyle G.

    2004-01-01

    This report presents results for year twelve in a basin-wide program to harvest northern pikeminnow1 (Ptychocheilus oregonensis). This program was started in an effort to reduce predation by northern pikeminnow on juvenile salmonids during their emigration from natal streams to the ocean. Earlier work in the Columbia River Basin suggested predation by northern pikeminnow on juvenile salmonids might account for most of the 10-20% mortality juvenile salmonids experience in each of eight Columbia River and Snake River reservoirs. Modeling simulations based on work in John Day Reservoir from 1982 through 1988 indicated that, if predator-size northern pikeminnow were exploited at a 10-20% rate, the resulting restructuring of their population could reduce their predation on juvenile salmonids by 50%. To test this hypothesis, we implemented a sport-reward angling fishery and a commercial longline fishery in the John Day Pool in 1990. We also conducted an angling fishery in areas inaccessible to the public at four dams on the mainstem Columbia River and at Ice Harbor Dam on the Snake River. Based on the success of these limited efforts, we implemented three test fisheries on a system-wide scale in 1991--a tribal longline fishery above Bonneville Dam, a sport-reward fishery, and a dam-angling fishery. Low catch of target fish and high cost of implementation resulted in discontinuation of the tribal longline fishery. However, the sport-reward and dam-angling fisheries were continued in 1992 and 1993. In 1992, we investigated the feasibility of implementing a commercial longline fishery in the Columbia River below Bonneville Dam and found that implementation of this fishery was also infeasible. Estimates of combined annual exploitation rates resulting from the sport-reward and damangling fisheries remained at the low end of our target range of 10-20%. This suggested the need for additional effective harvest techniques. During 1991 and 1992, we developed and tested a modified

  19. Development of a System-Wide Predator Control Program: Stepwise Implementation of a Predation Index, Predator Control Fisheries, and Evaluation Plan in the Columbia River Basin; Northern Pikeminnow Management Program, 2000 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Porter, Russell G.; Glaser, Bryce G.; Amren, Jennifer

    2003-03-01

    This report presents results for year ten in a basin-wide program to harvest northern pikeminnow (Ptychocheilus oregonensis). This program was started in an effort to reduce predation by northern pikeminnow on juvenile salmonids during their emigration from natal streams to the ocean. Earlier work in the Columbia River Basin suggested predation by northern pikeminnow on juvenile salmonids might account for most of the 10-20% mortality juvenile salmonids experience in each of eight Columbia River and Snake River reservoirs. Modeling simulations based on work in John Day Reservoir from 1982 through 1988 indicated that, if predator-size northern pikeminnow were exploited at a 10-20% rate, the resulting restructuring of their population could reduce their predation on juvenile salmonids by 50%. To test this hypothesis, we implemented a sport-reward angling fishery and a commercial longline fishery in the John Day Pool in 1990. We also conducted an angling fishery in areas inaccessible to the public at four dams on the mainstem Columbia River and at Ice Harbor Dam on the Snake River. Based on the success of these limited efforts, we implemented three test fisheries on a system-wide scale in 1991--a tribal longline fishery above Bonneville Dam, a sport-reward fishery, and a dam-angling fishery. Low catch of target fish and high cost of implementation resulted in discontinuation of the tribal longline fishery. However, the sport-reward and dam-angling fisheries were continued in 1992 and 1993. In 1992, we investigated the feasibility of implementing a commercial longline fishery in the Columbia River below Bonneville Dam and found that implementation of this fishery was also infeasible. Estimates of combined annual exploitation rates resulting from the sport-reward and damangling fisheries remained at the low end of our target range of 10-20%. This suggested the need for additional effective harvest techniques. During 1991 and 1992, we developed and tested a modified

  20. Algunos efectos de la precipitación del huracán Paulina en Acapulco, Guerrero

    Directory of Open Access Journals (Sweden)

    Lucía Guadalupe Matías Ramírez

    1998-01-01

    Full Text Available El huracán Pauiina se presentó del 6 al 10 de octubre de 1997, afectando las costas de los estados de Chiapas, Guerrero y Oaxaca. Se convirtió en huracán categoría 4 dentro de la escala Saffir-Simpson (eutremadamente peligroso, con vientos mayores de 210 kmlh y rachas de 240 kmih; esto produjo una precipitación mayor de 400 mm, durante cinco horas. en Acapulco, Guerrero, lo que originó impoitantes escunimientos. que provocaron derrumbes, inundaciones y la muerte de más de 120 personas. Los datios estimados fueron cercanos a los $300 millones de pesos.

  1. Integrated geographic information systems (IGIS) analysis and definition of the tectonic framework of northern Mexico

    Science.gov (United States)

    Martinez Pina, Carlos Manuel

    Crustal rupture structures reactivated in the course of the tectonic history of northern Mexico are the surface expressions of planes of weakness, in the form of simple or composite rectilinear features or slightly curved, defined as lineaments. Unless otherwise defined as strike-slip faults, lineaments are part of parallel and sub-parallel oblique convergent or oblique divergent tectonic zones cross cutting the Sierra Madre Occidental and northern Mexico, in a NW trend. These shear zones are the response to the oblique subduction of the Farallon plate beneath North America. Kinematic analysis of five selected sites in northern Mexico, three basins and two compressional shear zones, proved possible a combination of shear mechanism diagram and models from analogue materials, with satellite imagery and geographic information systems, as an aid to define strike-slip fault motion. This was done using a reverse engineering process by comparing geometries. One of the sites assessed, involving the Parras Basin, Coahuila Block (CB), San Marcos fault, a postulated PBF-1 fault, allowed for palinpastic reconstruction of the CB that corroborated the results of the vector motion defined, in addition to an extension of ˜25% in a northwest southeast direction. A GIS-based compilation and georeferenced regional structural studies by several researchers were used as ground control areas (GCA); their interpolation and interpretation, resulted in a tectonic framework map of northern Mexico. In addition, shaded relief models overlaid by the lineaments / fault layer allowed structural analyses of basins related to these major structures. Two important results were obtained from this study: the Tepehuanes-San Luis-fault (TSL) and the Guadalupe fault, named herein, displaces the Villa de Reyes graben, and the Aguascalientes graben, respectively, to the SE, confirming their left lateral vector motion; afterwards TSL was displaced south by the right lateral strike slip Taxco-San Miguel de

  2. Jurassic evaporite facies of the Afghan-Tajik and Amu Darya basins in northern Afghanistan and adjacent areas (evapfacafg.shp)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This shapefile contains polygons that describe the spatial extent of Jurassic age evaporite facies (Gaurdak formation) in the Afghan-Tajik and Amu Darya basins.

  3. Thickness of Jurassic evaporite facies in the Afghan-Tajik and Amu Darya basins of northern Afghanistan and adjacent areas (evapisoafg.shp)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This shapefile contains polylines (isopachs) that describe the thickness of Jurassic age evaporite facies (Gaurdak formation) in the Afghan-Tajik and Amu Darya basins

  4. Dynamics of hydrocarbon accumulation in the west section of the northern margin of the Qaidam Basin, NW China%柴达木盆地北缘西段油气成藏动力学研究

    Institute of Scientific and Technical Information of China (English)

    罗晓容; 孙盈; 汪立群; 肖安成; 马立协; 张晓宝; 王兆明; 宋成鹏

    2013-01-01

    Studies were conducted on the dynamic processes of hydrocarbon migration and accumulation in the west part of the northern margin of the Qaidam Basin, based on previous studies on basin evolution and hydrocarbon system. Based on the dynamics of petroleum accumulation, basin analysis and the numerical stimulation method were applied to reconstruct the basin evolution. Simulation analysis of petroleum accumulation in the main reservoir-forming stages were conducted in the light of source rock properties in different stages, fluid potential field and physical property distribution of carrier beds. Controlling factors of reservoir formation in the northern margin of the Qaidam Basin were summarized. Studies showed that the Miocene is the main period of oil generation for the Jurassic source rocks in the studied area. The oil generation and migration volume were large. However, Saishiteng Sag was just on the slope in the northern part of Yiliping Sag. Structural traps were distributed at the margin of the basin. There was abundant oil migration to the north margin and a dissipation of the oil there during the later strong tectonic activities. During the late reservoir formation stage after the Pliocene, the source rocks generated mainly gas and not oil, and structural traps were well developed and provided good conditions for the natural gas reservoir formation. Deep structural traps in the basins were conducive to the formation of a large-scale low-permeability gas reservoir.%  综合前人对柴达木北缘盆地演化和含油气系统的研究成果,遵循油气成藏动力学研究的思路和方法,以动态成藏要素研究为主线,采用盆地分析和数值模拟方法,恢复盆地演化过程;综合考虑不同时期烃源岩特征、流体势场及主要输导层输导物性分布,对主要成藏期的油气运聚过程进行了模拟分析,总结了柴北缘油气成藏的主控因素及成藏规律。研究结果表明,中新世是研

  5. Effects of recharge and discharge on delta2H and delta18O composition and chloride concentration of high arsenic/fluoride groundwater from the Datong Basin, northern China.

    Science.gov (United States)

    Xie, Xianjun; Wang, Yanxin; Su, Chunli; Duan, Mengyu

    2013-02-01

    To better understand the effects of recharge and discharge on the hydrogeochemistry of high levels of arsenic (As) and fluoride (F) in groundwater, environmental isotopic composition (delta2H and delta18O) and chloride (Cl) concentrations were analyzed in 29 groundwater samples collected from the Datong Basin. High arsenic groundwater samples (As > 50 micog/L) were found to be enriched in lighter isotopic composition that ranged from -92 to -78 per thousand for deuterium (delta2H) and from -12.5 to -9.9 per thousand for oxygen-18 (delta18O). High F-containing groundwater (F > 1 mg/L) was relatively enriched in heavier isotopic composition and varied from -90 to -57 per thousand and from -12.2 to -6.7 per thousand for delta2H and delta18O, respectively. High chloride concentrations and delta18O values were primarily measured in groundwater samples from the northern and southwestern portions of the study area, indicating the effect of evaporation on groundwater. The observation of relatively homogenized and low delta18O values and chloride concentrations in groundwater samples from central part of the Datong Basin might be a result of fast recharge by irrigation returns, which suggests that irrigation using arsenic-contaminated groundwater affected the occurrence of high arsenic-containing groundwater in the basin.

  6. Effects of recharge and discharge on delta2H and delta18O composition and chloride concentration of high arsenic/fluoride groundwater from the Datong Basin, northern China.

    Science.gov (United States)

    Xie, Xianjun; Wang, Yanxin; Su, Chunli; Duan, Mengyu

    2013-02-01

    To better understand the effects of recharge and discharge on the hydrogeochemistry of high levels of arsenic (As) and fluoride (F) in groundwater, environmental isotopic composition (delta2H and delta18O) and chloride (Cl) concentrations were analyzed in 29 groundwater samples collected from the Datong Basin. High arsenic groundwater samples (As > 50 micog/L) were found to be enriched in lighter isotopic composition that ranged from -92 to -78 per thousand for deuterium (delta2H) and from -12.5 to -9.9 per thousand for oxygen-18 (delta18O). High F-containing groundwater (F > 1 mg/L) was relatively enriched in heavier isotopic composition and varied from -90 to -57 per thousand and from -12.2 to -6.7 per thousand for delta2H and delta18O, respectively. High chloride concentrations and delta18O values were primarily measured in groundwater samples from the northern and southwestern portions of the study area, indicating the effect of evaporation on groundwater. The observation of relatively homogenized and low delta18O values and chloride concentrations in groundwater samples from central part of the Datong Basin might be a result of fast recharge by irrigation returns, which suggests that irrigation using arsenic-contaminated groundwater affected the occurrence of high arsenic-containing groundwater in the basin. PMID:23472327

  7. Geochemistry of the subduction-related magmatic rocks in the Dahong Mountains, northern Hubei Province--Constraint on the existence and subduction of the eastern Mianlüe oceanic basin

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    The existence and subduction of the eastern Mianlue oceanic basin in the south Qinling belt are keys to understand the Qinling orogen. Based on geological mapping, several volcanic slices have been identified in Tumen, Zhoujiawan, Xiaofu and Yuantan areas, which distribute in the northern margin of the Dahong Mountains (DHM), and thrust into the Sanligang-Sanyang fault. These slices consist mainly of diabases, basaltic-andesitic lavas, pyroclastic rocks and a minor tuff. The geochemistry of the basalts, andesites, and diabases is characterized by depleting in Nb and Ta, enriching in Th and LILE (e.g.K, Rb, Ba), and undifferentiating in HFSE. These geochemical characteristics suggest that the original magma of these rocks was derived from a mantle wedge above a subduction zone, and formed in an island-arc setting in Carboniferous-early Triassic. Comparing with the ophiolites and island-arc volcanic rocks in Mianxian-Lueyang area to the west, it is reasonable to consider that there had been an oceanic basin connecting with the Mianlue ancient ocean to the westward, distributing along the south edge of the Tongbai-Dabie block. In view of the ophiolite in Huashan area and these island-arc volcanic rocks along the north of the Dahong Mountains, it is suggested that there had been a plate tectonic evolutionary history with oceanic basin rifting and subduction in this region.

  8. Palaeoenvironment and dating of the Early Acheulean localities from the Somme River basin (Northern France): New discoveries from the High Terrace at Abbeville-Carrière Carpentier

    Science.gov (United States)

    Antoine, Pierre; Moncel, Marie-Hélène; Limondin-Lozouet, Nicole; Locht, Jean-Luc; Bahain, Jean-Jacques; Moreno, Davinia; Voinchet, Pierre; Auguste, Patrick; Stoetzel, Emmanuelle; Dabkowski, Julie; Bello, Silvia M.; Parfitt, Simon A.; Tombret, Olivier; Hardy, Bruce

    2016-10-01

    Dating the earliest human occupations in Western Europe and reconstructing links with climatic and environmental constraints is a central issue in Quaternary studies. Amongst the discovery of Palaeolithic artefacts ascribed to the Early Pleistocene in southeast Britain and central France the Somme Basin, where the Acheulean type-site Amiens Saint-Acheul is located, is a key area for addressing this topic. Research undertaken over the past 20 years on both Quaternary fluvial and loess sequences of this area has provided a unique dataset for the study of the relations between human occupations and environmental variations. Studies based on an interdisciplinary approach combining sedimentology, palaeontology and geochronology have highlighted the impact of the 100 kyrs cycles on terrace formation during the last million years. In this terrace system, the earliest in situ Acheulean settlements known in the 1990s were dated to early MIS 12 (±450 ka), but new field discoveries, at Amiens "Rue du Manège", dated to ± 550 ka, significantly increase the age of the oldest human occupation in the area. In this context, new fieldwork has been undertaken in Abbeville at the Carrière Carpentier site, famous for its White Marl deposit attributed to the Cromerian and in the same terrace level where the former discoveries of "Abbevillian bifaces" were made by d'Ault du Mesnil. This research is based on an interdisciplinary approach, combining sedimentology, paleontology, dating (ESR on quartz and ESR/U-series on teeth) and archaeology. According to the various bio-proxies (molluscs, large vertebrates, small mammals), the White Marl was deposited during the early part of an interglacial phase in an aquatic slow-flowing environment, as emphasized by the development of oncoliths and the presence of fish and aquatic molluscs. The landscape was composed of a mosaic of open bush and forest areas, in which wet and grassy vegetation developed on riverbanks. On the basis of terrace

  9. BODY CONDITION OF SPRING MIGRATORY FEMALE NORTHERN PINTAILS AND MEASURES OF PLASMA LIPID METABOLITES TO ASSESS HABITAT QUALITY IN THE RAINWATER BASIN

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Northern Pintails Anas acuta are below population goals and low survivability or reproductive success has contributed to population decline. Survivability and...

  10. Relationship between volcanism and marine sedimentation in northern Austral (Aisén) Basin, central Patagonia: Stratigraphic, U-Pb SHRIMP and paleontologic evidence

    Science.gov (United States)

    Suárez, M.; De La Cruz, R.; Aguirre-Urreta, B.; Fanning, M.

    2009-04-01

    The northernmost part of the oil-producing Austral Basin, known as Aisén Basin or Río Mayo Embayment (in central Patagonian Cordillera; 43-46°S), is a special area within the basin where the interplay between volcanism and the initial stages of its development can be established. Stratigraphic, paleontologic and five new U-Pb SHRIMP age determinations presented here indicate that the Aisén Basin was synchronous with the later phases of volcanism of the Ibáñez Formation for at least 11 m.yr. during the Tithonian to early Hauterivian. In this basin marine sedimentary rocks of the basal units of the Coihaique Group accumulated overlying and interfingering with the Ibáñez Formation, which represents the youngest episode of volcanism of a mainly Jurassic acid large igneous province (Chon Aike Province). Five new U-Pb SHRIMP magmatic ages ranging between 140.3 ± 1.0 and 136.1 ± 1.6 Ma (early Valanginian to early Hauterivian) were obtained from the Ibáñez Formation whilst ammonites from the overlying and interfingering Toqui Formation, the basal unit of the Coihaique Group, indicate Tithonian, early Berriasian and late Berriasian ages. The latter was a synvolcanic shallow marine facies accumulated in an intra-arc setting, subsequently developed into a retro-arc basin.

  11. Magmatism, sedimentation and stratigraphy of the northern region of the Santos Basin; Magmatismo, sedimentacao e estratigrafia da porcao norte da Bacia de Santos

    Energy Technology Data Exchange (ETDEWEB)

    Moreira, Jobel Lourenco Pinheiro [PETROBRAS S.A., Rio de de Janeiro, RJ (Brazil). E e P. Grupo de Interpretacao Exploratoria da Bacia de Santos], E-mail: jobel@petrobras.com.br; Esteves, Carlos Augusto; Rodrigues, Jose Joaquim Goncalves; Vasconcelos, Claudemir Severiano de

    2005-11-15

    The Santos Basin, passive margin basin, had its sedimentary history disrupted by intra and extra-basinal tectonic activity that took place during the Eocene and Santonian-Campanian. Many authors have identified these events; however this matter still deserves an integrated study including basement and basin areas. Recent Ar/Ar geochronological data from intrusive and extrusive rocks in the Santos basin have identified two events precisely at 82 {+-} 1 Ma and 48,9 Ma. Among the depositional sequences individualized from seismic and well data in the Santos Basin, the K90 depositional sequence - of Santonian- Campanian age - is the best example to investigate magmatism, sedimentation and stratigraphy. Substantial volcanic building, intrusive and extrusive rocks can be observed in this sequence and have a strong impact on in the mineralogical and sedimentary composition of the siliciclastic deposits (sandstones and shales). Subaerial and subaqueous volcanisms are well identified and its characteristics are described herein in terms of seismic facies, log facies and lithofacies. Siliciclastic depositional systems from the transgressive tract (shallow marine) and from lowstand (deep marine) of this sequence are lithic arkosean sandstones, composed mainly by quartz, Kfeldspar, plagioclase and fragments of igneous rocks. An intensive diagenetic chloritization, probably due to the presence of ferromagnesian minerals, has a strong impact on the reservoir quality. (author)

  12. Earthquake triggering by slow earthquake propagation: the case of the large 2014 slow slip event in Guerrero, Mexico.

    Science.gov (United States)

    Radiguet, M.; Perfettini, H.; Cotte, N.; Gualandi, A.; Kostoglodov, V.; Lhomme, T.; Walpersdorf, A.; Campillo, M.; Valette, B.

    2015-12-01

    Since their discovery nearly two decades ago, the importance of slow slip events (SSEs) in the processes of strain accommodation in subduction zones has been revealed. Nevertheless, the influence of slow aseismic slip on the nucleation of large earthquakes remains unclear. In this study, we focus on the Guerrero region of the Central American subduction zone in Mexico, where large SSEs have been observed since 1998, with a recurrence period of about 4 years, and produce aseismic slip in the Guerrero seismic gap. We investigate the large 2014 SSE (equivalent Mw=7.7), which initiated in early 2014 and lasted until the end of October 2014. During this time period, the 18 April Papanoa earthquake (Mw7.2) occurred on the western limit of the Guerrero gap. We invert the continuous GPS time series using the PCAIM (Principal Component Analysis Inversion Method) to assess the space and time evolution of slip on the subduction. To focus on the aseismic processes, we correct the cGPS time series from the co-seismic offsets. Our results show that the slow slip event initiated in the Guerrero gap region, as already observed during the previous SSEs. The Mw7.2 Papanoa earthquake occurred on the western limit of the region that was slipping aseismically before the earthquake. After the Papanoa earthquake, the aseismic slip rate increases. This geodetic signal consists of both the ongoing SSE and the postseismic (afterslip) response due to the Papanoa earthquake. The majority of the post-earthquake aseismic slip is concentrated downdip from the main earthquake asperity, but significant slip is also observed in the Guerrero gap region. Compared to previous SSEs in that region, the 2014 SSE produced a larger aseismic slip and the maximum slip is located downdip from the main brittle asperity corresponding to the Papanoa earthquake, a region that was not identified as active during the previous SSEs. Since the Mw 7.2 Papanoa earthquake occurred about 2 months after the onset of the

  13. A new perspective on the Guerrero gap: Slow slip events and tremors

    Science.gov (United States)

    Radiguet, Mathilde; Campillo, Michel

    2010-05-01

    The slow slip events (SSE) that have been detected in several subduction zones are characterized by an important variability (in terms of duration, migration, recurrence time). The physical mechanisms responsible for their occurrence and their role in the mechanical evolution leading to large thrust classic earthquakes are still unclear. Two of the largest events recorded occurred in 2002 and 2006 in the Guerrero segment of the Mexican subduction zone. These events where recorded by 8 and 15 continuous GPS stations respectively, and give us a good opportunity to constrain the characteristics of large SSEs. The total slip during the 2006 SSE has been also measured with InSAR. Combining GPS and InSAR allows a detailed study of the spatial and temporal evolution of slip at depth. We inverted the cumulative GPS displacements to find the distribution of total slip on the fault plane during the 2002 and 2006 SSEs. The two events show significantly different slip distributions, both extending in the deeper part of the seismogenic zone and in the transition zone. For the 2006 SSE, we modeled the spatial and temporal evolution of slip on the subduction interface by inverting the GPS time series. We assumed a functional form for the slip function, and we inverted for the slip amplitude, the initiation time and the duration, using a linearized least-square inversion procedure. The rupture initiated at a depth of 40 km (transition zone), in the western part of the Guerrero gap, and propagated with an average velocity of 1.2 km/day (with regional variations). The rise time (duration of slip in each cell) is about 170 days and the total duration of the event is 11-12 months. We also analyzed the energy of seismic records to detect non-volcanic tremors (NVT). We found that NVT are not synchronous with SSE slip and are separated spatially with the zones of large slip of the SSE. It is nevertheless observed that the NVT activity increased during the 2006 SSE. G-GAP team (LGIT

  14. Electrical and well log study of the Plio-Quaternary deposits of the southern part of the Rharb Basin, northern Morocco

    Science.gov (United States)

    El Bouhaddioui, Mohamed; Mridekh, Abdelaziz; Kili, Malika; El Mansouri, Bouabid; El Gasmi, El Houssine; Magrane, Bouchaib

    2016-11-01

    The Rharb Basin is located in the NW of Morocco. It is the onshore extension of a lager offshore basin between Kenitra and Moulay Bousselham. The Rharb plain (properly called) extends over an area of 4200 Km2 between two very different structural entities: the unstable Rif domain in the NE and the East and the ''relatively stable'' Meseta domain in the south. The distribution of Pliocene-Quaternary deposits under this plain is complex and was controlled by both tectonics and climatic factors. The main objective of the present work is to define the spatiotemporal evolution of these deposits in the onshore part of the basin and to make a comparison with a sequence analysis defined, for equivalent deposits in the offshore basin, by a previous work. The proposed model allows thus to characterize the geometry of these deposits in the extension of continental shelf under the present day onshore basin, and to explain there is genesis in terms of interactions between eustatic sea level fluctuations, tectonics and sedimentary rates at the mouths of paleo-rivers that had drained the Rharb plain during Pliocene to Quaternary Times.

  15. Lithology and late postglacial stratigraphy of bottom sediments in isolated basins of the White Sea coast exemplified by a small lake in the Chupa settlement area (Northern Karelia)

    Science.gov (United States)

    Korsakova, O. P.; Kolka, V. V.; Tolstobrova, A. N.; Lavrova, N. B.; Tolstobrov, D. S.; Shelekhova, T. S.

    2016-05-01

    The complex lithological, geochemical, geochronological, and micropaleontological (diatoms, spores, pollen) investigations of stratified bottom sediments that constitute facies-variable sedimentary sequences in a small isolated lake located near the upper limit of the sea on the White Sea coast made it possible to define lithostratigraphic units (LSU) forming the complete sedimentary succession in deep parts of isolated basins. It is shown that stratigraphy of heterogeneous sequences is determined by two regional transgressive-regressive cycles in relative sea level fluctuations: alternating late Glacial and Holocene transgressions and regressions. The lower part of a clastogenic clayey-sandy-silty sequence successively composed of freshwater (LSU 1) and brackish-water (LSU 2) sediments of the ice-marginal basins and marine postglacial facies (LSU 3) was formed during the late Glacial glacioeustatic marine transgression. Its upper part formed in different isolated basins at different stages of the Holocene is represented depending on its altimetric position on the coastal slope by costal marine sediments (LSU 4) and facies of the partly isolated inlet (LSU 5). The organogenic sapropelic sequence, which overlies sediments of the marine basin and partly isolated bay, corresponds to lithostratigraphic units represented by Holocene sediments accumulated in the meromictic lake (LSU 6), onshore freshwater basin (LSU 7), and freshwater basin with elevated water mineralization (LSU 8) deposited during maximum development of Holocene transgression and lacustrine sediments (LSU 9) formed in coastal environments during terminal phases of the Holocene. The defined lithostratigraphic units differ from each other in lithological, micropaleontological, and geochemical features reflected in structural and textural properties of their sediments, their composition, inclusions, and composition of paleophytocoenoses and diatom assemblages.

  16. Perspectiva territorial de la pesca en la Costa Chica de Guerrero

    Directory of Open Access Journals (Sweden)

    Salvador Villerías Salinas

    2010-01-01

    Full Text Available Este trabajo examina la actividad pesquera desde un punto de vista territorial, en uno de los litorales más marginados del trópico mexicano: la Costa Chica de Guerrero. La idea central de investigación relaciona y concatena la existencia de recursos pesqueros medianamente importantes, la falta de infraestructura adecuada y de eslabonamientos hacia delante de la pesca con la industria alimentaria y la presencia de canales de comercialización monopolizados por intermediarios; se asume que estos factores inciden en forma directa en las condiciones de vida de la población de los sitios estudiados, caracterizadas como poco favorables y que alientan la emigración. Entre los hallazgos de investigación relevantes se pueden indicar los siguientes: el predominio de explotación referido a unas cuantas especies con alto valor comercial, como el ostión; la primacía de Acapulco como centro de acopio de los productos pesqueros y una débil organización de las cooperativas pesqueras que se manifiesta en una incapacidad para resolver los problemas derivados de la comercialización de sus capturas, lo que abre una ventana de oportunidad para los intermediarios.

  17. A new species of nematode (Molineidae) from Rhinella marina (Amphibia: Bufonidae) in Guerrero, México.

    Science.gov (United States)

    Ruiz-Torres, Nallely; García-Prieto, Luis; Osorio-Sarabia, David; Violante-González, Juan

    2013-06-01

    Oswaldocruzia lamotheargumedoi n. sp., inhabiting the intestine of the cane toad, Rhinella marina (L.), in Laguna de Coyuca, Guerrero, México, is described here. The new species differs from 10 congeners infecting bufonid hosts because it has a type I bursa. In contrast, 7 of these species have type II bursa and 3 more a type III bursa. The species most similar to the species described herein is Oswaldocruzia pipiens Walton, 1929 . These 2 species share traits such as body size, bursa type, presence of cervical alae, and dorsal ray morphology. Nevertheless, both species can be distinguished based on the number of synlophe ridges at mid-body (54-56 for O. lamotheargumedoi vs. 45-48 for O. pipiens) and by the presence of a chitinous support in the long, and well developed, cervical alae of O. pipiens. In the new species, these structures are short, poorly developed, and lack chitinous support. Previous records of species of Oswaldocruzia in México include Oswaldocruzia subauricularis (Rudolphi, 1819) Travassos, 1917 in the Neotropical Realm and O. pipiens in the Nearctic.

  18. Competencias genéricas en docentes del nivel superior en el Estado de Guerrero

    Directory of Open Access Journals (Sweden)

    Leonila Román Fernández

    2016-02-01

    Full Text Available El objetivo del presente trabajo es identificar las competencias genéricas de los docentes que orientan la práctica educativa de nivel superior en el estado de Guerrero, en opinión de los estudiantes. Para ello se utilizó el método de estudio descriptivo y longitudinal en el periodo 2012-2014, y se aplicó un cuestionario a estudiantes de 7 instituciones. La muestra consistió en 37 % docentes y 41 % estudiantes por institución, evaluando a cada académico 10 jóvenes. La información se adaptó con valores de la escala de Likert, posteriormente a escala numérica de Sampieri para obtener cuartiles, clasificando en competencias altas, medianas y bajas. Las fortalezas y debilidades en indicadores fueron calculadas utilizando la media aritmética, y clasificadas con la mediana. Los resultados fueron: a nivel estatal 56 % de los docentes poseen competencias altas y 44 % entre medianas y bajas.

  19. 50 years of water extraction in the Pampa del Tamarugal basin: Can Prosopis tamarugo trees survive in the hyper-arid Atacama Desert (Northern Chile)?

    NARCIS (Netherlands)

    Chávez Oyanadel, R.O.; Clevers, J.G.P.W.; Decuyper, M.; Bruin, de S.; Herold, M.

    2016-01-01

    Groundwater-dependent ecosystems are threatened worldwide by unsustainable groundwater (GW) extraction. This is the case of the Prosopis tamarugo Phil forest in the hyper-arid Atacama Desert (Northern Chile), one of the most extreme ecosystems on Earth. Despite concerns about the conservation of thi

  20. Microstructures of Early Jurassic (Toarcian) shales of Northern Europe

    NARCIS (Netherlands)

    Houben, M.E.; Barnhoorn, A.; Wasch, L.; Trabucho-Alexandre, João; Peach, C.J.; Drury, M.R.

    2016-01-01

    The Toarcian (Early Jurassic) Posidonia Shale Formation is a possible unconventional gas source in Northern Europe and occurs within the Cleveland Basin (United Kingdom), the Anglo-Paris Basin (France), the Lower Saxony Basin and the Southwest Germany Basin (Germany), and the Roer Valley Graben, the

  1. Detrital zircon U-Pb and (U-Th)/He double-dating of Upper Cretaceous-Cenozoic Zagros foreland basin strata in the Kurdistan Region of northern Iraq

    Science.gov (United States)

    Barber, D. E.; Stockli, D. F.; Koshnaw, R. I.; Horton, B. K.; Tamar-Agha, M. Y.; Kendall, J. J.

    2014-12-01

    The NW Zagros orogen is the result of the multistage collisional history associated with Late Cretaceous-Cenozoic convergence of the Arabian and Eurasian continents and final closure of Neotethys. Siliciclastic strata preserved within a ~400 km segment of the NW Zagros fold-thrust belt and foreland basin in the Iraqi Kurdistan Region (IKR) provide a widespread record of exhumation and sedimentation. As a means of assessing NW Zagros foreland basin evolution and chronostratigraphy, we present coupled detrital zircon (DZ) U-Pb and (U-Th)/He geo-thermochronometric data of Upper Cretaceous to Pliocene siliciclastic strata from the Duhok, Erbil, and Suleimaniyah provinces of IKR. LA-ICP-MS U-Pb age analyses reveal that the foreland basin fill in IKR in general was dominantly derived from Pan-African/Arabian-Nubian, Peri-Gondwandan, Eurasian, and Cretaceous volcanic arc terrenes. However, the provenance of these strata varies systematically along strike and through time, with an overall increase in complexity upsection. DZ age distribution of Paleocene-Eocene strata is dominated by a ~95 Ma grain age population, likely sourced from the Late Cretaceous Hassanbag-Bitlis volcanic arc complex along the northern margin of Arabia. In contrast, DZ U-Pb age distributions of Neogene strata show a major contribution derived from various Eurasian (e.g., Iranian, Tauride, Pontide; ~45, 150, 300 Ma) and Pan-African (~550, 950 Ma) sources. The introduction of Eurasian DZ ages at the Paleogene-Neogene transition likely records the onset of Arabian-Eurasian collision. Along strike to the southeast, the DZ U-Pb spectra of Neogene strata show a decreased percentage of Pan-African, Peri-Gondwandan, Tauride, and Ordovician ages, coupled with a dramatic increase in 40-50 Ma DZ ages that correspond to Urumieh-Dokhtar magmatic rocks in Iran. Combined with paleocurrent data, this suggests that Neogene sediments were transported longitudinally southeastward through an unbroken foreland basin

  2. Violencia física intrafamiliar contra la embarazada: un estudio con base poblacional en Ometepec, Guerrero, México Violence during pregnancy: a population based study in Ometepec, Guerrero, Mexico

    OpenAIRE

    Sergio Paredes-Solís; Ascencio Villegas-Arrizón; Alba Meneses-Rentería; Irma Esther Rodríguez-Ramos; Luisa Reyes-De Jesús; Neil Andersson

    2005-01-01

    OBJETIVO: Estimar la ocurrencia de la violencia física intrafamiliar contra la embarazada, factores asociados y percepción de daños a la salud, en un estudio con base poblacional. MATERIAL Y MÉTODOS: Un grupo de enfermeras aplicó, una encuesta en cada hogar de Ometepec, Guerrero, México, a las mujeres que notificaron al menos un embarazo en los tres años previos a la encuesta. RESULTADOS: Se realizó una entrevista a 2 389 mujeres, de las cuales 709 fueron elegibles para completar el cuestiona...

  3. Occurrence of ignimbrite volcanics in the northern Espirito Santo Basin, Brazil: an advance in the model of tectonic-sedimentary evolution of the basin; Ocorrencia de rochas vulcanicas ignimbriticas na porcao norte da Bacia do Espirito Santo: evolucao do modelo tectono-sedimentar

    Energy Technology Data Exchange (ETDEWEB)

    Novais, Luis Carlos Chaves [PETROBRAS, ES (Brazil). Unidade de Negocio de Exploracao e Producao do Espirito Santo. Gerencia de Reservatorios], e-mail: novais@petrobras.com.br; Zelenka, Tibor [University of Miskolc (Hungary). Dept. of Geology], e-mail: zelenka.tibor@freemail.hu; Szatmari, Peter [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas Leopoldo A. Miguez de Mello. Gerencia de Geologia Estrutural e Geotectonica], e-mail: szatmari@petrobras.com.br; Motoki, Akihisa [Universidade do Estado do Rio de Janeiro (UERJ), RJ (Brazil). Dept. de Mineralogia e Petrologia Ignea], e-mail: motoki@uerj.br; Aires, Jose Ribeiro [PETROBRAS, Rio de Janeiro, RJ (Brazil). Abastecimento-Petroquimica e Fertilizantes. Gerencia Setorial de Seguranca, Meio Ambiente e Saude], e-mail: aires@petrobras.com.br; Tagliari, Claudio VInicius [PETROBRAS, ES (Brazil). Unidade de Negocio de Exploracao e Producao do Espirito Santo. Gerencia de Avaliacao de Blocos e Interpretacao Geologica e Geofisica], e-mail: tagliari@petrobras.com.br

    2007-11-15

    The intention of this work is to provide information on ignimbrite volcanoclastics, outcropping in the northern onshore part of the Espirito Santo Basin, and to examine their role in the tectonic-sedimentary evolution of the basin. We identified ignimbrites, pyroclastics of rhyolitic to dacitic composition, along the NNW-SSE to NW-SE trending transcurrent fault system named here Sao Mateus Alignment or Sao Mateus Arch. We followed the mostly horizontally layered ignimbrites, at least 50 m thick, for about 10 km along and close to the margins of the Sao Mateus River. These ignimbrite bodies had been mapped before as fluvio-lacustrine sandstones of the Tertiary Rio Doce/Barreiras Formation, without recognizing their partially volcanoclastic character. Microscopic examination suggests idiomorphic and fragmented {proportional_to}-quartz phenocrysts, contained in a hydrothermally altered matrix of clay minerals and zeolites. The fragmented form of the phenocrysts points to explosive volcanic activity; grain size tends to increase westward, probably indicating the principal place of volcanic centers. The outcropping sequence of ignimbritic rocks provides a major advance in the understanding of the basin's Cenozoic tectonic-structural history contributing to a revision of its stratigraphy. (author)

  4. Etiología e incidencia de hongos asociados al manchado de cálices de jamaica (Hibiscus sabdariffa L.) en Guerrero, México.

    OpenAIRE

    Martínez Sánchez, Cinthia

    2011-01-01

    El cultivo de la jamaica (Hibiscus sabdariffa L) es una de las actividades agrícolas importantes en el estado de Guerrero, así como una de las principales fuentes de ingresos monetarios y una alternativa para la diversificación de la actividad agrícola de la región. Este cultivo, en las zonas productoras de Guerrero, se ha visto afectado en los años recientes, por una enfermedad que se caracteriza por un manchado en la superficie del cáliz, situación que afecta a los productores a la hora de ...

  5. Sequence Stratigraphy and Sedimentary Facies of Lower Oligocene Yacheng Formation in Deepwater Area of Qiongdongnan Basin, Northern South China Sea:Implications for Coal-Bearing Source Rocks

    Institute of Scientific and Technical Information of China (English)

    Jinfeng Ren; Hua Wang; Ming Sun; Huajun Gan; Guangzeng Song; Zhipeng Sun

    2014-01-01

    For unveiling coal-bearing source rocks in terrestrial-marine transitional sequences, the sequence stratigraphic framework and sedimentary facies of Lower Oligocene Yacheng Formation of Qiongdongnan Basin were investigated using seismic profiles, complemented by well bores and cores. Three third-order sequences are identified on the basis of unconformities on basin margins and cor-relative conformities in the basin center, namely SQYC3, SQYC2 and SQYC1 from bottom to top. Coal measure in Yacheng Formation of Qiongdongnan Basin were deposited within a range of facies asso-ciations from delta plain/tidal zone to neritic sea, and three types of favourable sedimentary facies as-sociations for coal measure were established within the sequence stratigraphic framework, including braided delta plain and alluvial fan, lagoon and tidal flat, and fan delta and coastal plain facies associa-tions. Results shown that, in the third-order sequences, coal accumulation in landward areas (such as delta plain) of the study area predominantly correlates with the early transgressive systems tract (TST) to middle highstand systems tract (HST), while in seaward areas (such as tidal flat-lagoon) it correlates with the early TST and middle HST. The most potential coal-bearing source rocks formed where the accommodation creation rate (Ra) and the peat-accumulation rate (Rp) could reach a state of balance, which varied among different sedimentary settings. Furthermore, intense tectonic subsidence and fre-quent alternative marine-continental changes of Yacheng Formation during the middle rift stage were the main reasons why the coal beds shown the characteristics of multi-beds, thin single-bed, and rapidly lateral changes. The proposed sedimentary facies associations may aid in predicting distribution of coal-bearing source rocks. This study also demonstrates that controlling factors analysis using sequence stratigraphy and sedimentology may serve as an effective approach for coal

  6. Cultivable microflora and endo mycorrhizas obtained in litter forest (Paramo Guerrero - Finca Puente de Tierra) Zipaquira, Colombia

    International Nuclear Information System (INIS)

    The count of cultivable microorganisms (bacteria and fungi), cellulolytic microorganisms and endo mycorrhizas present in litter forest (property Puente de Tierra) in the Guerrero's moor, Colombia was made. The most frequently isolated microorganisms belonged to the staphylococcus, bacillus, pseudomonas, micrococcus, penicillium and rhodotorulagenus and cladosporium sp., which is a cellulolytic microorganism, was isolated in carboxymethyl cellulose agar. In addition eight morphotypes of endomycorrhizas were found, species of glomus and acaulospora predominated among them. This study contributes with the knowledge of the cultivable microorganisms of litter that have been little explored in moor ecosystems

  7. DETECCIÓN DE GEMINIVIRUS ASOCIADOS A LA ALSTROEMERIA (Alstroemeria L.) EN VILLA GUERRERO, ESTADO DE MÉXICO

    OpenAIRE

    Lourdes Cervantes-Díaz; Emma Zavaleta-Mejía; Reina Isabel Rojas-Martínez; Iobana Alanís-Martínez; Daniel Leobardo Ochoa-Martínez; Ernestina Valadez-Moctezuma; Onécimo Grimaldo-Juárez

    2009-01-01

    En plantaciones de alstroemeria (Alstroemeria L.) de Villa Guerrero, Estado de México, se han detectado plantas con síntomas similares a los inducidos por geminivirus en otros cultivos hortícolas. En dichas plantaciones también se ha observado la presencia de la mosquita blanca, considerada como el vector más eficiente de estos virus. El objetivo del presente trabajo fue detectar la presencia de geminivirus en plantas de alstroemeria. Mediante PCR, usando los iniciadores MotCP2118/MotCP2123, ...

  8. Manejo de la resistencia a insecticidas en el mosquito Aades aegypti (Linneus, 1762) en Guerrero, México.

    OpenAIRE

    Chino Cantor, Araceli

    2014-01-01

    El dengue es una de las enfermedades más graves a nivel mundial en salud pública, y a la fecha el uso de insecticidas químicos ha sido la principal medida de control del vector Aedes aegypti transmisor del virus causal del dengue. Con la finalidad de aportar bases para definir una estrategia de manejo regional de insecticidas, se determinó la susceptibilidad de poblaciones de Aedes aegypti L., provenientes de tres regiones de Guerrero, México (Tierra Caliente, Costa Chica y Acapulco), a los i...

  9. Patterns of microbial diversity along a salinity gradient in the Guerrero Negro solar saltern, Baja CA Sur, Mexico

    OpenAIRE

    Dillon, Jesse G.; Carlin, Mark; Gutierrez, Abraham; Nguyen, Vivian; McLain, Nathan

    2013-01-01

    The goal of this study was to use environmental sequencing of 16S rRNA and bop genes to compare the diversity of planktonic bacteria and archaea across ponds with increasing salinity in the Exportadora de Sal (ESSA) evaporative saltern in Guerrero Negro, Baja CA S., Mexico. We hypothesized that diverse communities of heterotrophic bacteria and archaea would be found in the ESSA ponds, but that bacterial diversity would decrease relative to archaea at the highest salinities. Archaeal 16S rRNA ...

  10. Responses of streamflow to climate change in the northern slope of Tianshan Mountains in Xinjiang: A case study of the Toutun River basin

    Institute of Scientific and Technical Information of China (English)

    LI WeiHong; CHEN YaNing; HAO XingMing; HUANG Xiang; CHEN YaPeng

    2007-01-01

    A case study on the responses of streamflow to climate change in the Toutun River basin was carried out based on data analysis of streamflow, precipitation, and temperatures during the past 50 years.Temporal series of the streamflow change in the Toutun River basin was analyzed and tested using the Mann-Kendall nonparametric test. Results revealed that the annual runoff of the Toutun River had been in a monotonic decreasing trend for the past 50 years. Compared with the 1950s and 1960s, the annual runoff in the 1990s decreased by 4.0×105 m3 and 7.2×105 m3. The precipitation did not show monotonic trend during the past 50 years, but the annual temperature increased by 1.12℃ since the 1950s. Further data analysis indicated that the monthly runoff of the Toutun River decreased significantly from August to October, with precipitation displaying the similar pattern of seasonal change. Analysis suggests that the reduction of streamflow in the Toutun River basin is possibly caused by the seasonal change of precipitation, especially the precipitation reduction in summer, and temperature increases.

  11. Relationships between physical and chemical factors and aquatic macroinvertebrates in perennial streams in the arid northern mountain basin El Batinah, Oman

    OpenAIRE

    S. Boulaaba; S. Zrelli; Boumaiza, M.; B. Rossaro

    2014-01-01

    The relationships between physical properties, water chemistry and aquatic macroinvertebrates were investigated in riffles of four perennial streams in the arid northern Oman. Samples were collected monthly in autumn, winter and spring with a Surber net. Thirty two invertebrate taxa were recorded, most species are widely distributed, but few species with very restricted distribution were also captured. Diptera followed by Pulmonata, Coleoptera and Odonata were the most represented taxa, Trich...

  12. The Role of Biofilms in the Sedimentology of Actively Forming Gypsum Deposits at Guerrero Negro, Mexico

    Science.gov (United States)

    Vogel, Marilyn B.; Des Marais, David J.; Turk, Kendra A.; Parenteau, Mary N.; Jahnke, Linda L.; Kubo, Michael D. Y.

    2009-11-01

    Actively forming gypsum deposits at the Guerrero Negro sabkha and saltern system provided habitats for stratified, pigmented microbial communities that exhibited significant morphological and phylogenetic diversity. These deposits ranged from meter-thick gypsum crusts forming in saltern seawater concentration ponds to columnar microbial mats with internally crystallized gypsum granules developing in natural anchialine pools. Gypsum-depositing environments were categorized as forming precipitation surfaces, biofilm-supported surfaces, and clastic surfaces. Each surface type was described in terms of depositional environment, microbial diversity, mineralogy, and sedimentary fabrics. Precipitation surfaces developed in high-salinity subaqueous environments where rates of precipitation outpaced the accumulation of clastic, organic, and/or biofilm layers. These surfaces hosted endolithic biofilms comprised predominantly of oxygenic and anoxygenic phototrophs, sulfate-reducing bacteria, and bacteria from the phylum Bacteroidetes. Biofilm-supported deposits developed in lower-salinity subaqueous environments where light and low water-column turbulence supported dense benthic microbial communities comprised mainly of oxygenic phototrophs. In these settings, gypsum granules precipitated in the extracellular polymeric substance (EPS) matrix as individual granules exhibiting distinctive morphologies. Clastic surfaces developed in sabkha mudflats that included gypsum, carbonate, and siliclastic particles with thin gypsum/biofilm components. Clastic surfaces were influenced by subsurface brine sheets and capillary evaporation and precipitated subsedimentary gypsum discs in deeper regions. Biofilms appeared to influence both chemical and physical sedimentary processes in the various subaqueous and subaerially exposed environments studied. Biofilm interaction with chemical sedimentary processes included dissolution and granularization of precipitation surfaces, formation of

  13. Los sistemas de armamento vislumbrados en las figuras de guerreros del Occidente de México

    Directory of Open Access Journals (Sweden)

    Cervera Obregón, Marco Antonio

    2007-12-01

    Full Text Available The following work outlines some of the present details on the study of the war and armament in the designated cultural region like Mesoamérica. It presents in form makes specific the case of the cultural subarea of the West of Mexico, proposing like main archaeological indicator to know the phenomenon the war, the weapons and military tactics in the Preclassic and Classic periods, to the representations of soldiers recognized like part of the archaeological context of the calls Tumbas de Tiro. The study is based on a icongraphic analysis and of the design of the devices that carry these artistic manifestations, considering the respective archaeological limitations that altogether the region.

    El siguiente trabajo esboza algunos de los pormenores actuales sobre el estudio de la guerra y armamento en la macroregión cultural designada como Mesoamérica. Presenta en forma concreta el caso de la subárea cultural del Occidente de México, proponiendo como principal indicador arqueológico para conocer el fenómeno de la guerra, los sistemas de armamento y las tácticas militares en los periodos Preclásico y Clásico, a las representaciones de guerreros reconocidas como parte del contexto arqueológico de las llamadas Tumbas de Tiro. El estudio se basa en un análisis iconográfico y del diseño de los artefactos que portan dichas manifestaciones artísticas, considerando las respectivas limitaciones arqueológicas que en conjunto presenta la región.

  14. BASIS FOR IMPLEMENTING RESTORATION STRATEGIES: SAN NICOLÁS ZOYATLAN SOCIAL-ECOLOGICAL SYSTEM (GUERRERO, MEXICO

    Directory of Open Access Journals (Sweden)

    Virginia Cervantes Gutiérrez

    2014-06-01

    Full Text Available In Latin America, indigenous communities have been distinguished by continuous marginalization and degradation of their social-ecological systems (SES, and this is the case of San Nicolás Zoyatlan (Guerrero, Mexico. With the purpose of establishing restoration strategies, we conducted an in situ diagnosis to assess the current condition of the community and its disturbance factors. We combined methods of environmental and social sciences to analyze, in diachronic and synchronic contexts, how the SES’s natural resources are used. Results indicate that the chronic ecological disturbance of the SES and agrarian conflicts have contributed to the degradation of vegetation and soil. Thus, vegetation is impoverished, with secondary tropical deciduous forest (TDF shrub vegetation predominating, and the risk of soil degradation is high, despite the inhabitants’ knowledge and appreciation of this resource. To reverse degradation, we defined and established rehabilitation practices with the involvement of inhabitants. These comprised agroforestry systems (AFSs and plantations (PLs on community lands, using 18 native TDF species selected on the basis of local preferences. Our ongoing assessment indicates that after more than a decade, the AFSs and PLs are maintained and managed by the people, as reflected in the current size of plants whose inputs contribute to improve physical and chemical soil characteristics, such as soil aggregate formation, cation exchange capacity and organic matter content. However, we concluded that we need to confirm whether the ecosystem processes and environmental services are recovered and maintained over time, in addition to determining how they have influenced and will continue to influence the socioeconomic factors involved in maintaining rehabilitation practices.

  15. An Analysis of Late Mesozoic Tectonic Evolution Process in Northern China:Based on Basin Sedimentary Records in Northern Taihang Mountains%华北晚中生代构造演化过程--根据太行山北部盆地沉积记录

    Institute of Scientific and Technical Information of China (English)

    王永超; 董树文; 施炜; 岑敏; 李江瑜

    2016-01-01

    The northern Taihang Mountains are located at the junction of the Yanshan tectonic belt with the Taihang Mountains belt, and their superimposed basin development process documented the basin trending conversion process from EW to NE during Jurassic to Cretaceous, which is significant for depicting the intracontinental deformation process and its dynamic background during the late Mesozoic in North China. Caogoubu basin and Zhaobai basin located in northern Taihang Mountains were selected as examples in this paper. According to the basic structural framework analysis of basins in combination with isotope chronologic data from magmatic rocks and sedimentology methods which include the detailed analysis of sediment provenance, prototype basin reconstruction and so on, tectonic evolution history of the northern Taihang Mountains during the late Mesozoic can be detected, which includes four stage evolution sequences : (1) nearly N–S contraction and flexural basin development during the late middle Jurassic, (2) nearly N–S low-magnitude extention and crust sources volcanic eruption that occurred in the late Jurassic, (3) NW–SE contraction and foreland basin development from the end of the late Jurassic to the earliest Cretaceous, and (4) NW–SE extension and mantle sources volcanic eruption during the early Cretaceous. The conversion of tectonic regimes is essentially the transformation of its geodynamic systems, and on the context of the East Asia multi-direction convergent tectonic system during the Middle–Late Jurassic, the multi-phases tectonic and basin superposition that occurred in northern Taihang Mountains during the late Mesozoic indicates the conversion process during which the Mogolia–Okhotsk tectonic system graded into the Marginal–Pacific tectonic system.%太行山北部地区处于燕山山脉和太行山山脉的交汇处,其侏罗纪—白垩纪叠加盆地发育过程记录了东西向盆地向北东向盆地转化过程,对刻画华

  16. Western Gas Sands Project. Quarterly basin activities report, October 1-December 31, 1979

    Energy Technology Data Exchange (ETDEWEB)

    1979-01-01

    This report is a summation of three months drilling and testing activitie in the four primary study areas of the WGSP: Greater Green River Basin, Northern Great Plains Province, Piceance Basin, and Uinta Basin.

  17. Geochemical and Nd-Sr-Pb-O isotopic constrains on Permo-Triassic magmatism in eastern Qaidam Basin, northern Qinghai-Tibetan plateau: Implications for the evolution of the Paleo-Tethys

    Science.gov (United States)

    Chen, Xuanhua; Gehrels, George; Yin, An; Zhou, Qi; Huang, Penghui

    2015-12-01

    Eastern Qaidam Basin of the northern Qinghai-Tibetan plateau is located in a transitional zone between the Permo-Triassic Paleo-Tethyan orogenic belt in the south and the early Paleozoic Qilian orogenic belt in the north. Here we present geochemical and Sr-Nd-Pb-O isotopic data for the Permo-Triassic plutons in eastern Qaidam Basin. Bulk-rock geochemical data and regional geological studies indicate that these plutons consist mainly of subduction-related high-K calc-alkaline metaluminous, I-type granitoids, which occurred during the northward subduction of the Paleo-Tethyan oceanic lithosphere below the southern continental margin of the Kunlun-Qaidam terrane. The εNd(t) values of these Permo-Triassic granitoids are between -9.4 and -3.0, and εSr(t) values are from -20.33 to +168.20. Nd isotopic compositions indicate that the granitoids can come from a pre-existed materials formerly originated from an enriched mantle (EM II) source. The TDM2 model ages of 1.28-1.78 Ga implies that the arc-induced Triassic granitoids were derived melts of Meso-Proterozoic basement rocks of the Kunlun-Qaidam terrane that is bounded by the early Paleozoic Qilian suture zone to the north and the Triassic Kunlun suture zone in the south. The Permo-Triassic granitoids yield initial ratios of 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb values from 18.295 to 19.096, 15.617 to 15.692, and 37.960 to 38.531, respectively. The Pb isotope composition of the granitoids is very similar to that of the Mesozoic granitoids from the western segment of the east of the study area. Geochemical analyses of the plutons, integrated with previous LA ICP-MS U-Pb zircon dating, reveal two series of Permo-Triassic arc magmatisms in eastern Qaidam Basin. Both the series of magmatism display reversed trends with the classic Bowen's reaction series. The new geochemical evidence suggest that the arc magmatism in eastern Qaidam Basin was induced by fluid-fluxing melting of an enriched lithospheric mantle and rock

  18. High type I error and misrepresentations in search for transgenerational epigenetic inheritance: response to Guerrero-Bosagna.

    Science.gov (United States)

    Iqbal, Khursheed; Tran, Diana A; Li, Arthur X; Warden, Charles; Bai, Angela Y; Singh, Purnima; Madaj, Zach B; Winn, Mary E; Wu, Xiwei; Pfeifer, Gerd P; Szabó, Piroska E

    2016-01-01

    In a recent paper, we described our efforts in search for evidence supporting epigenetic transgenerational inheritance caused by endocrine disrupter chemicals. One aspect of our study was to compare genome-wide DNA methylation changes in the vinclozolin-exposed fetal male germ cells (n = 3) to control samples (n = 3), their counterparts in the next, unexposed, generation (n = 3 + 3) and also in adult spermatozoa (n = 2 + 2) in both generations. We reported finding zero common hits in the intersection of these four comparisons. In our interpretation, this result did not support the notion that DNA methylation provides a mechanism for a vinclozolin-induced transgenerational male infertility phenotype. In response to criticism by Guerrero-Bosagna regarding our statistical power in the above study, here we provide power calculations to clarify the statistical power of our study and to show the validity of our conclusions. We also explain here how our data is misinterpreted in the commentary by Guerrero-Bosagna by leaving out important data points from consideration.Please see related Correspondence article: xxx (13059_2016_982) and related Research article: http://genomebiology.biomedcentral.com/articles/10.1186/s13059-015-0619-z. PMID:27411809

  19. [Gender and work: the experience of providers of health services to indigenous women from Guerrero y Oaxaca].

    Science.gov (United States)

    Amaya-Castellanos, Claudia Isabel; Pelcastre-Villafuerte, Blanca; Márquez-Serrano, Margarita; Juárez-Ramírez, Clara

    2012-03-01

    The scope of this paper was to identify the role of gender for women as workers, through the perception and discourse of health service providers at the 'Health Centers for Indigenous Women' ("Casas de Salud de las Mujeres Indígenas") in Ometepec, Guerrero and Matías Romero, Oaxaca, Mexico. It is a qualitative study, based on a secondary analysis of the interviews conducted as part of the "Rescatando la experiencia de la Casa de la Mujer Indígena: sistematización y evaluación del proceso" project. A strong sense of the value of work and a strong commitment towards the community were identified. Guilt appears as the result of tension between work outside the home and the responsibilities as mothers and wives. The possibility of helping other women is a source of gratification that dissipates these conflicts; prestige and recognition are added to the benefits of their role. The labor experience of female workers in the "Casas de Salud de las Mujeres Indígenas" of Matías Romero, Oaxaca and Ometepec, Guerrero, described in this paper, reveals that it has very specific characteristics, which are difficult to replicate in other regions of the country. In future studies it is necessary to consider the different contexts of vulnerability. PMID:22450415

  20. [Gender and work: the experience of providers of health services to indigenous women from Guerrero y Oaxaca].

    Science.gov (United States)

    Amaya-Castellanos, Claudia Isabel; Pelcastre-Villafuerte, Blanca; Márquez-Serrano, Margarita; Juárez-Ramírez, Clara

    2012-03-01

    The scope of this paper was to identify the role of gender for women as workers, through the perception and discourse of health service providers at the 'Health Centers for Indigenous Women' ("Casas de Salud de las Mujeres Indígenas") in Ometepec, Guerrero and Matías Romero, Oaxaca, Mexico. It is a qualitative study, based on a secondary analysis of the interviews conducted as part of the "Rescatando la experiencia de la Casa de la Mujer Indígena: sistematización y evaluación del proceso" project. A strong sense of the value of work and a strong commitment towards the community were identified. Guilt appears as the result of tension between work outside the home and the responsibilities as mothers and wives. The possibility of helping other women is a source of gratification that dissipates these conflicts; prestige and recognition are added to the benefits of their role. The labor experience of female workers in the "Casas de Salud de las Mujeres Indígenas" of Matías Romero, Oaxaca and Ometepec, Guerrero, described in this paper, reveals that it has very specific characteristics, which are difficult to replicate in other regions of the country. In future studies it is necessary to consider the different contexts of vulnerability.

  1. Characterisation of an enamelled metallic object found in Guerrero Negro (Baja California) by PIXE and RBS techniques

    Energy Technology Data Exchange (ETDEWEB)

    Calvo del Castillo, H. [Departamento de Geologia y Geoquimica, Universidad Autonoma de Madrid (Spain); Instituto de Fisica, Universidad Nacional Autonoma de Mexico (Mexico); Centre Europeen d' Archeometrie - I.P.N.A.S., Universite de Liege, Allee du 6 Aout, 10 Bat-15, Sart Tilman, 4000-Liege 1 (Belgium)], E-mail: hcalvo@ulg.ac.be; Ruvalcaba, J.L. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico (Mexico); Calderon, T. [Departamento de Geologia y Geoquimica, Universidad Autonoma de Madrid (Spain); Salinas Nolasco, M.F. [Coordinacion de Conservacion del Patrimonio Cultural, Instituto Nacional de Antropologia e Historia (Mexico); Mejia, L.M. [Direccion de Arqueologia Subacuatica, Instituto Nacional de Antropologia e Historia (Mexico); Perdigon, K. [Coordinacion de Conservacion del Patrimonio Cultural, Instituto Nacional de Antropologia e Historia (Mexico)

    2008-05-15

    The coast of Guerrero Negro (Baja California) has been known for a long time by archaeologists for its shipwrecks. Archaeologists are recovering objects that come from sunken Spanish galleons in the colonial period, and reach the American coast in the frontier of the USA with Mexico. An enamelled metallic object was found next to the beach in Guerrero Negro. We have analysed the piece with proton induced X-ray emission (PIXE) and Rutherford backscattering (RBS) in an attempt to establish whether the object could come from one of the colonial shipwrecks and to valuate its cleaning process. Scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS) have been also performed in three samples taken from the object in order to observe the heterogeneity of the material. The materials found revealed the presence of typical lead-glass enamels from with pigments such as cuprite (red), or lead-tin yellow used in colonial times. The metallic part consisted of brass. As for the cleaning process, the average efficiency considered as the weight% of chlorine removed, was of 83.4% for brass and 100% for ename0008.

  2. Ground-Water Flow Model of the Sierra Vista Subwatershed and Sonoran Portions of the Upper San Pedro Basin, Southeastern Arizona, United States, and Northern Sonora, Mexico

    Science.gov (United States)

    Pool, D.R.; Dickinson, Jesse E.

    2007-01-01

    A numerical ground-water model was developed to simulate seasonal and long-term variations in ground-water flow in the Sierra Vista subwatershed, Arizona, United States, and Sonora, Mexico, portions of the Upper San Pedro Basin. This model includes the simulation of details of the groundwater flow system that were not simulated by previous models, such as ground-water flow in the sedimentary rocks that surround and underlie the alluvial basin deposits, withdrawals for dewatering purposes at the Tombstone mine, discharge to springs in the Huachuca Mountains, thick low-permeability intervals of silt and clay that separate the ground-water flow system into deep-confined and shallow-unconfined systems, ephemeral-channel recharge, and seasonal variations in ground-water discharge by wells and evapotranspiration. Steady-state and transient conditions during 1902-2003 were simulated by using a five-layer numerical ground- water flow model representing multiple hydrogeologic units. Hydraulic properties of model layers, streamflow, and evapotranspiration rates were estimated as part of the calibration process by using observed water levels, vertical hydraulic gradients, streamflow, and estimated evapotranspiration rates as constraints. Simulations approximate observed water-level trends throughout most of the model area and streamflow trends at the Charleston streamflow-gaging station on the San Pedro River. Differences in observed and simulated water levels, streamflow, and evapotranspiration could be reduced through simulation of climate-related variations in recharge rates and recharge from flood-flow infiltration.

  3. Extent of slow slip events in the Guerrero seismic gap (Mexico): observations from space-borne SAR interferometry

    Science.gov (United States)

    Pathier, E.; Bacques, G.; Doin, M.; Cavalié, O.; Radiguet, M.; Lasserre, C.; Cotte, N.; Walpersdorf, A.

    2013-12-01

    Since 1998, four slow slip events (SSEs) have been recorded by geodesy in the Guerrero state of Mexico. They occurred on the subduction interface where the Coco plate subducts at about 6 cm/year beneath the North-America plate. SSEs spatially overlap the seismic gap of Guerrero which is a 100km-long portion of the Mexican subduction zone where no significant earthquakes have occurred since 1911. This duration contrasts with the average recurrence time of 30-60 years for large subduction earthquakes observed along the Mexican subduction zone (Nishenko and Singh, 1987a). To the west, the gap is limited by the slip distribution of the 1979 (M=7.6) and the 1985 (M=8.1) earthquakes, and to the east by the 1957 (M=7.8) and 1962 Acapulco events (M=7 and 7.1). An important issue is to know whether SSEs penetrate into the seismogenic zone and whether they are restricted to the seismic gap or have a larger extent. Radiguet et al, (2012) studied three SSEs that occurred in 2002, 2006 and 2009-2010, based on continuous GPS data. They show that SSEs have variable lateral extents, with significant slip within the 100km-long seismic gap, but also occurring on a wider area with a 250 km lateral extension when considering slip downdip the seismogenic zone (estimated to end at about 25km depth according to Suarez et al, 1990). Within the gap, results from Radiguet et al. suggest also that SSE can propagate shallower than the 25 km limit and that, west of the gap, the aseismic slip overlaps the 1979 and the 1985 earthquakes coseismic slip distribution. However, the GPS network design used in their analysis is mainly composed of two perpendicular profiles: a profile along the coast and a profile perpendicular to the coast from Acapulco to Mexico. Away from these profiles the resolution of the SSE location decreases rapidly, which limits the analysis of SSE extents. Here, we used space-borne SAR interferometry (InSAR) to overcome this limitation. Despite atmospheric and decorrelation

  4. Western Gas Sands Project. Quarterly Basin Activities Report

    Energy Technology Data Exchange (ETDEWEB)

    Atkinson, C H

    1979-01-31

    This report is a summation of 3 months' drilling and testing activities in the four primary WGSP study areas: Greater Green River Basin, Northern Great Plains Province, Piceance Basin, and Uinta Basin. The monitoring of basin activities is part of resource assessment. (DLC)

  5. Western Gas Sands Project Quarterly Basin Activities Report

    Energy Technology Data Exchange (ETDEWEB)

    Atkinson, C H

    1979-04-30

    This quarterly basin activities report is a summation of three months drilling and testing activities in the Greater Green River Basin, Northern Great Plains Province, Piceance Basin, and Uinta Basin. Detailed information is given for each study area for the first quarter of 1979.

  6. Lanthanide behavior in hypersaline evaporation ponds at Guerrero Negro, Baja California, Mexico - an environment with halophiles

    Science.gov (United States)

    Choumiline, K.; López-Cortés, A.; Grajeda-Muñoz, M.; Shumilin, E.; Sapozhnikov, D.

    2013-12-01

    Lanthanides are known, in some cases, to be sensitive to changes in water column or sediment chemistry, a fact that allows them to be used as environmental fingerprints. Nevertheless, the behavior of these elements in hypersaline environments is insufficiently understood, especially in those colonized by bacteria, archaea and eukarya halophiles. Extreme environments like the mentioned exist in the artificially-controlled ponds of the 'Exportadora de Sal' salt-producing enterprise located in Guerrero Negro (Baja California, Mexico). Sediment cores from various ponds were collected, subsampled and measured by ICP-MS and INAA. This allowed differencing the behavior of lanthanides and trace elements under a water column salinity gradient along the evaporation sequence of ponds. Sediment profiles (30 mm long), obtained in Pond 5, dominated by Ca and Mg precipitation and at the same time rich in organic matter due to bacterial mat presence, showed highs and lows of the shale-normalized patterns along different in-core depths. Two groups of elements could be distinguished with similar trends: set A (La, Ce, Pr and Nd) and set B (Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu). The first 'group A' had two prominent peaks at 15 mm and around 22 mm, whereas the 'group B' showed only slight increase at 15 mm and none at 22 mm. Microscopic analyses of prokaryotic cells of a stratified mat in Pond 5 (collected in 2004) showed filamentous bacteria and cyanobacteria with a cell abundance and morphotype richness maxima of prokaryotic cells in a chemocline from 3 mm to 7 mm depth which co-exists nine morphotypes of aerobic and anaerobic prokaryotes Microcoleus chthonoplastes, Leptolyngbya, Cyanothece, Geitlerinema, Spirulina, Chloroflexus, Beggiatoa, Chromatium and Thioploca. Below the 7 mm depth, oxygenic photosynthesis depletes and sulfur reducing compounds increase. The highs of the shale-normalized lanthanide contents of the 'group A' (at 15 mm depth) seem to correlate with the

  7. Echinoderms associated with reef formations in Zihuatanejo and Acapulco, Guerrero, Mexico

    Directory of Open Access Journals (Sweden)

    Pablo Zamorano

    2009-12-01

    Full Text Available Knowledge of echinoderms from Zihuatanejo and Acapulco, Guerrero is currently limited to taxonomic listings. This work attempts to characterize better the community of these organisms associatedto coral reefs in this region using band transects of 50 m length by 1 m width. Two samplings were carried out in 2004, one in the rainy season and other in the dry season. Ten species, three Asteroidea,six Echinoidea and one Holothuroidea, were found. The mean values obtained for diversity in the 13 study sites (1.036 bits ind-1 are considered low when compared with the maximum possible diversity(3.322 bits ind-1, and this is likely due to the dominance of the black sea urchin Diadema mexicanum and the starsh Phataria unifascialis, with densities reported of 1.45±0.60 ind m-2 and 0.12±0.02 ind m-2, respectively. The highest diversity was associated with low tide, which is not different between localities.The spatial arrangement of the echinoderm species composition obtained by the multidimensional scaling analysis denotes the formation of ve conglomerates according to similarity, where the substratum and reef cover are the possible determinant variables. The four predominant species (D. mexicanum, P. unifascialis, Toxopneustes roseus and Hesperocidaris asteriscus, whose densities were compared with those of other sites of the Oriental Tropical Pacic, show, in general, inferior values for Echinoidea and intermediate values for the Asteroidea. For the specic case of D. mexicanum, there are differences in the densities between localities, depths, and time of year, and the mean value obtained of 1.45±0.60 ind m-2 was low compared to densities recorded in other zones. Also, it was observed that in some localities, such as Playa Coral, Caleta de Chon, Punta del Cerro Colorado, and Zacatoso, the sea urchin densities increased considerably during the rainy season, and these high densities maintain a positive correlation with coral cover, which is indicative

  8. Intraslab Fluid Migration During Slow Slip Earthquakes and Nonvolcanic Tremors in Guerrero, Mexico.

    Science.gov (United States)

    Villafuerte, C. D.; Cruz-Atienza, V. M.

    2014-12-01

    Observations in different subduction zones have suggested that overpressured fluids nearby the plate interface are closely related to the origin of nonvolcanic tremors (NVT) and low frequency earthquakes (LFE). The physics of the plate interface would strongly differ depending on whether NVT and LFE triggering is produced by fluid migration due to the SSE strain field or, to the long-term fluid emplacement induced by the slip transients. In this work we study the migration of confined fluids in the subducted Cocos plate during two SSE in Guerrero. To this purpose we coupled the evolution of the 3D strain field induced by the silent events of 2006 and 2009-2010 with the 2D poroelastic equation for fluid transport. We considered the SSE slip history determined by previous authors through the inversion of GPS data and used a 3D finite difference code to compute the evolution of the associated confining pressure in the crust. As a result, we obtained the velocity vectors of the fluids within the top 5 km of the Cocos plate (i.e., slab) assuming typical permeability values from 1x10-9-1x10-16 m2 reported in the literature for the oceanic crust. For the 2006 SSE, two low-pressure zones acting as fluid "attraction poles" arise at 150-175 and 200-230 km from the trench, with diffusion velocities ranging between 10-3 and 10-9 km/day. These zones surprisingly agree with the regions where NVTs are systematically observed during the occurrence of the SSEs. For the 2009-2010 SSE, which is composed by two successive slip transients, fluids essentially migrate towards the plate interface (i.e., upward) in its horizontal segment, where must of NVTs and LFEs seem to take place. Since the maximum Darcy's velocities for both events are of the order of meters per day (i.e., 3 orders of magnitude smaller than the migration speed of the LFE streaks), we concluded that the fluids diffusive transport is not responsible of the NVT and LFE migration during the SSEs. Instead, our results

  9. Detailed Tremor Migration Styles in Guerrero, Mexico Imaged with Cross-station Cross-correlations

    Science.gov (United States)

    Peng, Y.; Rubin, A. M.

    2015-12-01

    Tremor occurred downdip of the area that slipped the most during the 2006 slow slip event (SSE) in Guerrero, Mexico, as opposed to Cascadia, where tremor locations and rupture zones of SSEs largely overlap. Here we obtain high resolution tremor locations by applying cross-station cross-correlations [Armbruster et al., 2014] to seismic data from the Meso-America Subduction Experiment deployment. A few 3-station detectors are adopted to capture detailed deformation styles in the tremor "transient zone" and the downdip "sweet spot" as defined in Frank et al., 2014. Similar to Cascadia, tremor activities in our study region were comprised mostly of short tremor bursts lasting minutes to hours. Many of these bursts show clear migration patterns with propagation velocities of hundreds of km/day, comparable to those in Cascadia. However, the propagation of the main tremor front was often not in a simple unilateral fashion. Before the 2006 SSE, we observe 4 large tremor episodes during which both the transient zone and the sweet spot participated, consistent with previous findings [Frank et al., 2014]. The transient zone usually became active a few days after the sweet spot. We find many along-dip migrations with recurrence intervals of about a half day within a region about 10 km along strike and 35 km along dip in the sweet spot, suggesting possible tidal modulation, after the main front moved beyond this region. These migrations appear not to originate at the main front, in contrast to tremor migrations from a few km to tens of km across observed in Cascadia [Rubin and Armbruster, 2013; Peng et al., 2015; Peng and Rubin, submitted], but possibly similar to Shikoku, Japan [Shelly et al., 2007]. We do not observe obvious half-day periodicity for the migrations farther downdip within the sweet spot. During the SSE, the recurrence interval of tremor episodes decreased significantly in both the transient zone and the sweet spot, with that of the former being much shorter

  10. Depositional architecture and evolution of inner shelf to shelf edge delta systems since the Late Oliocene and their respone to the tectonic and sea level change, Pear River Mouth Basin, northern South China Sea

    Science.gov (United States)

    Lin, Changsong; Zhang, Zhongtao; liu, Jingyan; Jiang, Jing

    2016-04-01

    The Pear River Mouth Basin is located in the northern continent margin of the South China Sea. Since the Late Oligocene, the long-term active fluvial systems (Paleo-Zhujiang) from the western basin margin bebouched into the northern continental margin of the South China Sea and formed widespread deltaic deposits in various depositional geomorphologies and tectonic settings. Based of integral analysys of abundant seismic, well logging and drilling core data, Depositional architecture and evolution of these delta systems and their respone to the tectonic and sea level change are documented in the study. There are two basic types of the delta systems which have been recognized: inner shelf delta deposited in shallow water enviroments and the outer shelf or shelf-edge delta systems occurred in deep water settings. The paleowater depths of these delta systems are around 30 to 80m (inner shelf delta) and 400-1000m (shelf-edge delta) estimated from the thickness (decompaction) of the delta front sequences. The study shows that the inner shelf delta systems are characterized by relatively thin delta forests (20-40m), numereous stacked distributary channel fills, relative coarse river mouth bar deposits and thin distal delta front or distal bar and prodelta deposits. In contrast, the outer shelf or shelf edge delta systems are characteristic of thick (300-800m) and steep (4-60) of deltaic clinoforms, which commonly display in 3D seismic profiles as "S" shape reflection. Large scale soft-sediment deformation structures, slump or debris flow deposits consisting mainly of soft-sediment deformed beds, blocks of sandstones and siltstones or mudstones widely developed in the delta front deposits. The shelf edge delta systems are typically associated with sandy turbidite fan deposits along the prodelta slopes, which may shift basinwards as the progradation of the delta systems. The delta systems underwent several regional cycles of evolution from inner shelf deltas to shelf edge

  11. 宁芜北段火山岩型金矿类型及找矿方向%Types of volcanic rock gold deposits in northern Ningwu Basin and their prospecting direction

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    宁芜北段是长江中下游重要的火山岩型金矿成矿远景区。金矿类型繁多,主要有火山热液充填脉型金矿、陆相火山―沉积期后热液充填交代型金矿、蚀变破碎带型金矿、爆发角砾岩筒型金矿、铁帽型金矿以及伴生金。矿床主要受 NNE、NW 向区域性大断裂及其派生次级断裂控制,与安山质火山角砾岩、辉石闪长玢岩关系密切。梅山地区、铜井地区碱性火山岩内及外围、谷里地区及宁芜北段东部隆起带是今后的找矿方向。%Northern Ningwu Basin is an important volcanic rock type gold mineralization prospect area inside the regions along the middle and lower reaches of Yangtze River.Various types of gold deposits in this area include volcanic hydrothermal filling vein type gold deposit,continental volcano-post depositional hydrother-mal filling metasomatic gold deposit,alteration fracture zone type gold deposit,diatreme breccia pipe type gold deposit,gossan type gold deposit and associated gold deposit.The deposits are primarily controlled by NNE-and NW-trending regional major fractures and their derived subsidiary fractures,and they are closely related to andesitic volcanic breccia and pyroxene diorite porphyrite.The prospecting direction of this area are interior of the alkaline volcanic rocks and its peripheries in Meishan area and Tongjing area,as well as the uplift zone in Guli area and eastern part of northern Ningwu Basin.

  12. Whole water column distribution and carbon isotopic composition of bulk particulate organic carbon, cholesterol and brassicasterol from the Cape Basin to the northern Weddell Gyre in the Southern Ocean

    Directory of Open Access Journals (Sweden)

    A.-J. Cavagna

    2012-02-01

    Full Text Available The combination of concentrations and δ13C signatures of Particulate Organic Carbon (POC and sterols provides a powerful approach to study ecological and environmental changes both in the modern and ancient ocean, but its application has so far been restricted to the surface area. We applied this tool to study the biogeochemical changes in the modern ocean water column during the BONUS-GoodHope survey (Feb–Mar 2008 from Cape Basin to the northern part of the Weddell Gyre. Cholesterol and brassicasterol were chosen as ideal biomarkers of the heterotrophic and autotrophic carbon pools, respectively, because of their ubiquitous and relatively refractory nature.

    We document depth distributions of concentrations (relative to bulk POC and δ13C signatures of cholesterol and brassicasterol from the Cape Basin to the northern Weddell Gyre combined with CO2 aq. surface concentration variation. While relationships between surface water CO2 aq. and δ13C of bulk POC and biomarkers have been previously established for surface waters, our data show that these remain valid in deeper waters, suggesting that δ13C signatures of certain biomarkers could be developed as proxies for surface water CO2 aq. Our data suggest a key role of zooplankton fecal aggregates in carbon export for this part of the Southern Ocean. We observed a general increase in sterol δ13C signatures with depth, which is likely related to a combination of particle size effects, selective feeding on larger cells by zooplankton, and growth rate related effects Additionally, in the southern part of the transect south of the Polar Front (PF, the release of sea-ice algae is hypothesized to influence the isotopic signature of sterols in the open ocean. Overall, combined use of δ13C and concentrations measurements of both bulk organic C and specific sterol markers throughout the water

  13. Activation of northern margin of the North China Craton in Late Paleozoic: Evidence from U-Pb dating and Hf isotopes of detrital zircons from the Upper Carboniferous Taiyuan Formation in the Ningwu-Jingle basin

    Institute of Scientific and Technical Information of China (English)

    LI HongYan; XU YiGang; HUANG XiaoLong; HE Bin; LUO ZhenYu; YAN Bin

    2009-01-01

    LA-MC-ICPMS U-Pb dating has been performed on detrital zircons from the Upper Carboniferous Tai-yuan Formation (N-8) in the Ningwu-Jingle Basin, west of the North China Craton (NCC). The ages of 72 detrital zircon grains are divided into three groups: 303-320 Ma (6 grains), 1631-2194 Ma (37 grains, peaked at 1850 Ma), 2318-2646 Ma (29 grains, peaked at 2500 Ma). Detrital zircons of Group 2 and Group 3 were likely derived from the basement of the NCC. Group 1 zircons exhibit 176Hf/177Hf ratios ranging from 0.281725 to 0.282239, with corresponding negative εHf(t) values of -12.4-30.3 and old Hf model ages of 1.4-2.2 Ga. These characteristics show a strong resemblance to those of Carboniferous igneous zircons from the Inner Mongolia Paleo-uplift (IMPU) on the northern margin of the NCC, but differ significantly from those of the Xing-Meng Orogenic Belt, suggesting that the source of the Tai-yuan Formation partly came from the IMPU. All detrital zircons of Group 1 have relatively high Th/U ratios (0.67), indicating a magmatic origin. The mean age (304±6 Ma) of the two youngest grains is close to the depositional age of the Taiyuan Formation, suggesting a strong tectonic uplift and mag-matism in the IMPU during the Late Carboniferous. This paper provides important geological evidence for the activation of the northern margin of the NCC in the Late Paleozoic.

  14. Geochemistry and geodynamics of a Late Cretaceous bimodal volcanic association from the southern part of the Pannonian Basin in Slavonija (Northern Croatia)

    Science.gov (United States)

    Pamic, J.; Belak, M.; Bullen, T.D.; Lanphere, M.A.; McKee, E.H.

    2000-01-01

    In this paper we present petrological and geochemical information on a bimodal basaltrhyolite suite associated with A-type granites of Late Cretaceous age from the South Pannonian Basin in Slavonija (Croatia). Basalts and alkali-feldspar rhyolites, associated in some places with ignimbrites, occur in volcanic bodies that are interlayered with pyroclastic and fossiliferous Upper Cretaceus sedimentary rocks. The petrology and geochemistry of the basalts and alkali-feldspar rhyolites are constrained by microprobe analyses, major and trace element analyses including REE, and radiogenic and stable isotope data. Basalts that are mostly transformed into metabasalts (mainly spilites), are alkalic to subalkalic and their geochemical signatures, particularly trace element and REE patterns, are similar to recent back-arc basalts. Alkali-feldspar rhyolites have similar geochemical features to the associated cogenetic A-type granites, as shown by their large variation of Na2O and K2O (total 8-9%), very low MgO and CaO, and very high Zr contents ranging between 710 and 149ppm. Geochemical data indicate an amphibole lherzolite source within a metasomatized upper mantle wedge, with the influence of upper mantle diapir with MORB signatures and continental crust contamination. Sr incorporated in the primary basalt melt had an initial 87Sr/86Sr ratio of 0.7039 indicating an upper mantle origin, whereas the 87Sr/86Sr ratio for the alkalifeldspar rhyolites and associated A-type granites is 0.7073 indicating an apparent continental crust origin. However, some other geochemical data favour the idea that they might have mainly originated by fractionation of primary mafic melt coupled with contamination of continental crust. Only one rhyolite sample appears to be the product of melting of continental crust. Geological and geodynamic data indicate that the basalt-rhyolite association was probably related to Alpine subduction processes in the Dinaridic Tethys which can be correlated with

  15. CFD simulation on the generation of turbidites in deepwater areas:a case study of turbidity current processes in Qiongdongnan Basin, northern South China Sea

    Institute of Scientific and Technical Information of China (English)

    JIANG Tao; ZHANG Yingzhao; TANG Sulin; ZHANG Daojun; ZUO Qianmei; LIN Weiren; WANG Yahui; SUN Hui; WANG Bo

    2014-01-01

    Turbidity currents represent a major agent for sediment transport in lakes, seas and oceans. In particu-lar, they formulate the most significant clastic accumulations in the deep sea, which become many of the world’s most important hydrocarbon reservoirs. Several boreholes in the Qiongdongnan Basin, the north-western South China Sea, have recently revealed turbidity current deposits as significant hydrocarbon res-ervoirs. However, there are some arguments for the potential provenances. To solve this problem, it is es-sential to delineate their sedimentary processes as well as to evaluate their qualities as reservoir. Numerical simulations have been developed rapidly over the last several years, offering insights into turbidity current behaviors, as geologically significant turbidity currents are difficult to directly investigate due to their large scale and often destructive nature. Combined with the interpretation of the turbidity system based on high-resolution 3D seismic data, the paleotophography is acquired via a back-stripping seismic profile integrated with a borehole, i.e., Well A, in the western Qiongdongnan Basin; then a numerical model is built on the basis of this back-stripped profile. After defining the various turbidity current initial boundary conditions, includ-ing grain size, velocity and sediment concentration, the structures and behaviors of turbidity currents are investigated via numerical simulation software ANSYS FLUENT. Finally, the simulated turbidity deposits are compared with the interpreted sedimentary bodies based on 3D seismic data and the potential provenances of the revealed turbidites by Well A are discussed in details. The simulation results indicate that a sedimen-tary body develops far away from its source with an average grain size of 0.1 mm, i.e., sand-size sediment. Taking into account the location and orientation of the simulated seismic line, the consistence between normal forward simulation results and the revealed cores

  16. Passive seismic experiment and receiver functions analysis to determine crustal structure at the contact of the northern Dinarides and southwestern Pannonian Basin

    Science.gov (United States)

    Šumanovac, Franjo; Hegedűs, Endre; Orešković, Jasna; Kolar, Saša; Kovács, Attila C.; Dudjak, Darko; Kovács, István J.

    2016-06-01

    Passive seismic experiment was carried out at the SW contact of the Dinarides and Pannonian basin to determine the crustal structure and velocity discontinuities. The aim of the experiment was to define the relationship between the Adriatic microplate and the Pannonian segment as a part of the European plate. Most of the temporary seismic stations were deployed in Croatia along the Alp07 profile-a part of the active-source ALP 2002 project. About 300-km-long profile stretches from Istra peninsula to the Drava river, in a WSW-ESE direction. Teleseismic events recorded on 13 temporary seismic stations along the profile were analysed by P-receiver function method. Two types of characteristic receiver functions (RF) have been identified, belonging to Dinaridic and Pannonian crusts as defined on the Alp07 profile, while in transitional zone there are both types. Three major crustal discontinuities can be identified for the Dinaridic type: sedimentary basement, intracrustal discontinuity and Mohorovičić discontinuity, whereas the Pannonian type revealed only two discontinuities. The intracrustal discontinuity was not observed in the Pannonian type, thus pointing to a single-layered crust in the Pannonian basin. Two interpretation methods were applied: forward modelling of the receiver functions and H-κ stacking method, and the results were compared with the active-source seismic data at deep refraction profile Alp07. The receiver function modelling has given reliable results of the Moho depths that are in accordance with the seismic refraction results at the end of the Alp07 profile, that is in the area of Pannonian crust characterized by simple crustal structure and low seismic velocities (Vp between 5.9 and 6.2 km s-1). In the Dinarides and its peripheral parts, receiver function modelling regularly gives greater Moho depths, up to +15 per cent, due to more complex crustal structure. The depths of the Moho calculated by the H-κ stacking method vary within wide

  17. Upper Cretaceous to Holocene magmatism and evidence for transient Miocene shallowing of the Andean subduction zone under the northern Neuquén Basin

    Science.gov (United States)

    Kay, Suzanne M.; Burns, W. Matthew; Copeland, Peter; Mancilla, Oscar

    2006-01-01

    Evidence for a Miocene period of transient shallow subduction under the Neuquén Basin in the Andean backarc, and an intermittent Upper Cretaceous to Holocene frontal arc with a relatively stable magma source and arc-to-trench geometry comes from new 40Ar/39Ar, major- and trace-element, and Sr, Pb, and Nd isotopic data on magmatic rocks from a transect at ∼36°–38°S. Older frontal arc magmas include early Paleogene volcanic rocks erupted after a strong Upper Cretaceous contractional deformation and mid-Eocene lavas erupted from arc centers displaced slightly to the east. Following a gap of some 15 m.y., ca. 26–20 Ma mafic to acidic arc-like magmas erupted in the extensional Cura Mallín intra-arc basin, and alkali olivine basalts with intraplate signatures erupted across the backarc. A major change followed as ca. 20–15 Ma basaltic andesite–dacitic magmas with weak arc signatures and 11.7 Ma Cerro Negro andesites with stronger arc signatures erupted in the near to middle backarc. They were followed by ca. 7.2–4.8 Ma high-K basaltic to dacitic hornblende-bearing magmas with arc-like high field strength element depletion that erupted in the Sierra de Chachahuén, some 500 km east of the trench. The chemistry of these Miocene rocks along with the regional deformational pattern support a transient period of shallow subduction that began at ca. 20 Ma and climaxed near 5 Ma. The subsequent widespread eruption of Pliocene to Pleistocene alkaline magmas with an intraplate chemistry in the Payenia large igneous province signaled a thickening mantle wedge above a steepening subduction zone. A pattern of decreasingly arc-like Pliocene to Holocene backarc lavas in the Tromen region culminated with the eruption of a 0.175 ± 0.025 Ma mafic andesite. The northwest-trending Cortaderas lineament, which generally marks the southern limit of Neogene backarc magmatism, is considered to mark the southern boundary of the transient shallow subduction zone.

  18. Petrological, geochemical and geochronological evidence for a Neoproterozoic ocean basin recorded in the Marlborough terrane of the northern New England Fold Belt

    International Nuclear Information System (INIS)

    Petrological, geochemical and radiogenic isotopic data on ophiolitic-type rocks from the Marlborough terrane, the largest (∼700 km2) ultramafic-mafic rock association in eastern Australia, argue strongly for a sea-floor spreading centre origin. Chromium spinel from partially serpentinised mantle harzburgite record average Cr/(Cr + Al) = 0.4 with associated mafic rocks displaying depleted MORB-like trace-element characteristics. A Sm/Nd isochron defined by whole-rock mafic samples yields a crystallisation age of 562 ± 22 Ma (2σ). These rocks are thus amongst the oldest rocks so far identified in the New England Fold Belt and suggest the presence of a late Neoproterozoic ocean basin to the east of the Tasman Line. The next oldest ultramafic rock association dated from the New England Fold Belt is ca 530 Ma and is interpreted as backarc in origin. These data suggest that the New England Fold Belt may have developed on oceanic crust, following an oceanward migration of the subduction zone at ca 540 Ma as recorded by deformation and metamorphism in the Anakie Inlier. Fragments of late Neoproterozoic oceanic lithosphere were accreted during progressive cratonisation of the east Australian margin. Copyright (1999) Geological Society of Australia

  19. Middle Miocene reworked turbidites in the Baiyun Sag of the Pearl River Mouth Basin, northern South China Sea margin: Processes, genesis, and implications

    Science.gov (United States)

    Gong, Chenglin; Wang, Yingmin; Zheng, Rongcai; Hernández-Molina, F. Javier; Li, Yun; Stow, Dorrik; Xu, Qiang; Brackenridge, Rachel E.

    2016-10-01

    Our understanding of reworked turbidites is still in its infancy, and their flow processes and genesis still remain understudied. Core data from the middle Miocene Zhujiang Formation in the Pearl River Mouth Basin allow us to differentiate reworked turbidites, yielding two main contributions. Firstly, reworked turbidites are distinguished from turbidites by the association of traction structures and tidal signatures, which occur in discrete units rather than forming a classic "Bouma Sequence" for turbidites. Sedimentological characteristics of reworked turbidites proposed here will help to obtain a robust set of diagnostic criteria for the recognition of deep-water non-turbidite deepwater units as reservoirs. Secondly, our results suggest that, in the down-slope direction, classic detritus carried in turbidity flows would synchronously be bidirectionally reworked by internal tides and waves, resulting in tidal signatures seen in the interpreted reworked turbidites. In the along-slope direction, upper parts of dilute turbidity currents would mix vertically with seawater, and muddy fines would be winnowed away by contour currents, whereas lower parts of dilute turbidity currents would probably drop their coarse particles, resulting in traction structures recognized in the documented reworked turbidites. Our work highlights the influence of bottom currents on the development and modification of turbidites and suggests that reworked turbidites were created by the combined action of down-slope transport and reworking and along-slope winnowing and sorting, helping to better understand flow processes and genesis of non-turbidite reservoirs with a great economic interest.

  20. Late Quaternary vegetation and climate history of a perennial river canyon in the Rīo Salado basin (22°S) of Northern Chile

    Science.gov (United States)

    Latorre, Claudio; Betancourt, Julio L.; Arroyo, Mary T.K.

    2006-01-01

    Plant macrofossils from 33 rodent middens sampled at three sites between 2910 and 3150 m elevation in the main canyon of the Rīo Salado, northern Chile, yield a unique record of vegetation and climate over the past 22,000 cal yr BP. Presence of low-elevation Prepuna taxa throughout the record suggests that mean annual temperature never cooled by more than 5°C and may have been near-modern at 16,270 cal yr BP. Displacements in the lower limits of Andean steppe and Puna taxa indicate that mean annual rainfall was twice modern at 17,520-16,270 cal yr BP. This pluvial event coincides with infilling of paleolake Tauca on the Bolivian Altiplano, increased ENSO activity inferred from a marine core near Lima, abrupt deglaciation in southern Chile, and Heinrich Event 1. Moderate to large increases in precipitation also occurred at 11,770-9550 (Central Atacama Pluvial Event), 7330-6720, 3490-2320 and at 800 cal yr BP. Desiccation occurred at 14,180, 8910-8640, and 4865 cal yr BP. Compared to other midden sites in the region, early Holocene desiccation seems to have happened progressively earlier farther south. Emerging trends from the cumulative midden record in the central Atacama agree at millennial timescales with improved paleolake chronologies for the Bolivian Altiplano, implying common forcing through changes in equatorial Pacific sea-surface temperature gradients.

  1. Potencial productivo de cruzas intervarietales de maíz en la región semicálida de Guerrero Maize intervarietal crosses productive potential in the semi-warm region of Guerrero

    Directory of Open Access Journals (Sweden)

    Francisco Palemón Alberto

    2012-02-01

    Full Text Available En las regiones semicálidas del estado de Guerrero (alrededor de 1 500 m de altitud, prevalece la siembra de semillas nativas (criollos, pero también se tienen áreas en las que se pueden establecer maíces mejorados. En el presente trabajo se proponen dos cruzas intervarietales como alternativa, para que los agricultores incrementen la producción de grano; estas se seleccionaron después de evaluar el comportamiento agronómico de cinco variedades progenitoras y sus cruzas posibles en arreglo factorial; dos de ellas, de origen tropical, seleccionadas al menos por 10 generaciones para adaptarse a los Valles Altos y las otras tres de germoplasma nativo subtropical, obtenidas en el estado de Guerrero; además, de las seis cruzas intervarietales y sus progenitores, se agregaron la variedad local del agricultor y seis variedades testigo para evaluarlos en un diseño de bloques completos al azar con cuatro repeticiones, en el ciclo primavera-verano de 2009, en dos localidades de altitud intermedia. El análisis combinado a través de ambientes mostró diferencias significativas en rendimiento de grano, entre cruzas, progenitores y testigos. Las cruzas intervarietales VS-529*VE-1 y VS-529*VE-3 fueron superiores en rendimiento de grano a sus progenitores, la variedad local del agricultor y los testigos comerciales tuvieron otros atributos, como mejor sanidad de mazorca y planta, expresión intermedia para altura de planta, días a floración masculina y femenina, y menor acame. Las variedades progenitoras subtropicales per se fueron ligeramente superiores en rendimiento de grano, peso de mazorca y diámetro de mazorca comparadas con las variedades tropicales, pero éstas presentaron ligeramente mejor sanidad de planta y mazorca. Los progenitores VE-1, VE-3 y VS-529 presentaron efectos de ACG positiva, sus cruzamientos fueron los que mostraron mayor rendimiento de grano, heterosis, precocidad, mejor aspecto de planta y mazorca, mientras que CIST y

  2. Preliminary Basin Analysis of Latest Miocene Conglomerate Near Bahía Kino, Coastal Sonora: A New Record of Crustal Deformation During Initial Opening of the Northern Gulf of California

    Science.gov (United States)

    Dorsey, R. J.; Peryam, T. C.; Bennett, S.; Oskin, M. E.; Iriondo, A.

    2008-12-01

    In coastal Sonora northwest of Bahía Kino, we have initiated a basin-analysis study of nonmarine conglomerate (Tcg) that overlies and is locally interbedded with the 6.4-Ma Tuff of Mesa Cuadrada (Tmc). Tcg conglomerate is deeply eroded and cut by a complex set of syn- to post-basinal, N- to NNE-striking normal faults and NW-striking dextral strike-slip faults. We carried out detailed mapping and field descriptions, measured stratigraphic sections, and collected paleocurrent and clast-count data in Tcg. Zircons from the newly discovered Seri tuff near the base of the section, 160 m below Tmc, were dated using U-Pb SHRIMP geochronology at Stanford University. We obtained a 206Pb/238U weighted mean age of 6.53+/-0.18 Ma (n=14; MSWD=1.3), which yields a sediment-accumulation rate of 0.8+/-0.2 mm/yr for lower Tcg. Tcg is dominated by debris-flow facies consisting of massive, poorly sorted, weakly bedded, matrix-rich, pebble, cobble, to small-boulder conglomerate. A subsidiary sheet-flood facies is somewhat better sorted, generally lacks boulders, and contains weak but pervasive horizontal stratification. Both facies of Tcg record deposition in an alluvial fan environment. Well sorted and stratified stream deposits are conspicuously lacking. Preserved sections of Tcg range up to 170 to 240 meters thick in the southern part of the study area, and increase to at least 470 meters in the north where the Punta Chueca fault, a large NW-directed low-angle normal fault, apparently produced more extension and subsidence than smaller faults in the south. Clasts in Tcg are dominated by middle Miocene andesite, the 12.6-Ma Tuff of San Felipe, minor amounts of Tmc, and variable amounts of older basement rocks including tonalite, granodiorite, quartzite, metavolcanic rock, and a megacrystic K-spar-bearing granite that we have not seen in the local bedrock. After correcting for bedding dips and vertical-axis clockwise rotations determined from paleomagnetic analysis, restored

  3. Taxco, Guerrero: hechos históricos, vida cotidiana y rutina diaria, lugares turísticos y festividades destacadas

    Directory of Open Access Journals (Sweden)

    Adrián Urióstegui Flores

    2016-01-01

    Full Text Available En este escrito se estudian 1 los hechos históricos, 2 la vida cotidiana y rutina diaria, 3 los lugares turísticos y 4 las festividades destacadas de la ciudad de Taxco de Alarcón, Guerrero. Básicamente, en la metodología se utilizó análisis bibliográfico, fenomenología etnográfica, observación participante e informantes clave. Entre los resultados destacan los sucesos históricos más importantes, así como una gran variedad de sitios turísticos y celebraciones en la comunidad, que influyen de manera determinante como factores de atracción de visitantes nacionales e internacionales.

  4. Evidencia geofísica del umbral de Trenque Lauquen en la extensión norte de la cuenca de Claromecó, provincia de Buenos Aires Geophysical evidence of the Trenque Lauquen High in the northern extension of the Claromecó Basin, province of Buenos Aires

    Directory of Open Access Journals (Sweden)

    J. Kostadinoff

    2007-11-01

    Full Text Available La exploración geofísica del borde norte de la cuenca de Claromecó sugieren la existencia de importantes espesores de sedimentos paleozoicos. Estas secuencias sedimentarias se extienden en el área NW de la provincia de Buenos Aires. Las cuencas de Claromecó y Chaco Paranense están divididas por un área semipositiva. Sin embargo un bajo con dirección NNO de 165 km de longitud, cubierto por sedimentos paleozoicos conecta ambas cuencas.The geophysical survey of the northern border of Claromecó basin suggests the existence of Paleozoic sequences with important thickness. Such sequences extend along the NW area of Buenos Aires province. The Claromecó and Chaco Paranense Basins are divided by a semi positive area. A NNW-trending through, 165 km long, filled with Paleozoic sediments connects important thickness of both basins.

  5. Evaluation of soil erosion as a basis of sediment yield in mountainous catchments: a preliminary study in the River Douro Basin (Northern Portugal)

    Science.gov (United States)

    Reis, Anabela; Martinho Lourenço, José M.; Parker, Andrew; Alencoão, Ana

    2013-04-01

    The River Corgo drains a meso-scale mountainous rural catchment with an area of 295 km2, underlain by crystalline rocks, in a temperate climate, which integrates the transboundary River Douro Basin, in the northeast of Portugal. A geochemical survey on oxic fluvial sediments of the river network shows considerable contents of metals associated to the finer particles (soils and weathering products. Moreover, taking into account the hydrological pattern of the catchment, the seasonal and spatial variability of metal contents associated to the sediments suggests that the control of metal in the sediments by their mineralogical, geochemical and physical properties is governed primarily at the level of the basin soils system, especially in the Wet Period, when the sediments are frequently remobilised (Reis, 2010). Although the soil particles are a common pathway of transport and entrance of metals in the fluvial network by runoff derived erosion, this mechanism is naturally more marked in mountainous catchments. Modelling sediment and adsorbed contaminant transport within catchments can help to identify possible contaminant sources, as well as to estimate the delivered quantities of eroded material and associated contaminants. In catchments with the described morphological features, monitoring the transport of sediments poses some issues concerning: (a) the low mass yield of suspended sediment from river water, under low-flow conditions; (b) the maintenance of the sediment sampler's devices in the streams, in periods of high-flow or storm events. This study describes the preliminary results of a GIS-based mass balance model of overland sediment transport to the River. The erosion, the first step of sediment transport, was estimated by an empirical model - The Universal Soil Loss Equation (USLE). The objective was to construct a GIS based potential soil loss spatial index model and posteriorly estimate the sediment yield for different locations within the catchment. The

  6. Influence of irrigation practices on arsenic mobilization: Evidence from isotope composition and Cl/Br ratios in groundwater from Datong Basin, northern China

    Science.gov (United States)

    Xie, Xianjun; Wang, Yanxin; Su, Chunli; Li, Junxia; Li, Mengdi

    2012-03-01

    SummaryEnvironment isotopes (δ18O and δ2H) and Cl/Br ratios in groundwater have been used to trace groundwater recharge and geochemical processes for arsenic contamination in Datong Basin. The arsenic concentrations of groundwater samples ranged from 0.4 to 434.9 μg/L with the average of 51.2 μg/L, which exceeded China's drinking water standard (10 μg/L). All the groundwater samples are plotted on or close to the meteoric water line of the δ18O vs. δ2H plot, indicating their meteoric origin. The relationship between δ18O values and Cl/Br ratios and Cl concentrations demonstrate that leaching and mixing are the dominant processes affecting the distribution of high arsenic groundwater in this area. The observed non-linearity in the trend between δ18O and arsenic concentration is due to combined effects of mixing and leaching. The similarity of the trend in Cl/Br ratios and δ18O values for high arsenic groundwater demonstrate that extensive leaching of irrigation return and salt flushing water flow could be the dominant process driving arsenic mobilization in the groundwater system. Moreover, the long term irrigation practice can cause the drastic change of the biogeochemical and redox condition of in the aquifer system, which in turn promotes the mobilization of arsenic. Therefore, groundwater pumping for irrigation in this area of waterborne endemic arsenic poisoning should be under strict control to protect groundwater quality in this area.

  7. Relationships between physical and chemical factors and aquatic macroinvertebrates in perennial streams in the arid northern mountain basin El Batinah, Oman

    Directory of Open Access Journals (Sweden)

    S. Boulaaba

    2014-08-01

    Full Text Available The relationships between physical properties, water chemistry and aquatic macroinvertebrates were investigated in riffles of four perennial streams in the arid northern Oman. Samples were collected monthly in autumn, winter and spring with a Surber net. Thirty two invertebrate taxa were recorded, most species are widely distributed, but few species with very restricted distribution were also captured. Diptera followed by Pulmonata, Coleoptera and Odonata were the most represented taxa, Trichoptera and Heteroptera were a significant component only in one station (the Fezeh, where the lowest mean water temperature (23°C was recorded. In the dry months from May to October, aquatic macroinvertebrates were completely absent. In order to summarise the community response some biotic indices were calculated. The highest diversity was observed in the Fezeh station. A seasonal gradient was also observed, with the highest diversity values in January, April, and December. The low faunal diversity was attributed to the high air and water temperature and the hydrological regime instability. A between station and a between month coinertia analysis was carried out, to analyse the response to spatial and seasonal factors. The first coinertia axis was correlated with altitude and substrate composition, while the second axis was correlated with air and water temperature. The present research emphasizes the urgency for preserving the less disturbed wadis in arid zones, because, despite their species poorness, their uniqueness in faunal composition requires special attention. The presence of few endemic species with very restricted distribution highlights the topicality and the value in investigating these areas, allowing the increase of our knowledge on biodiversity, ecology and biogeography about the benthic macroinvertebrates living in these extreme habitats.

  8. Plant-Arthropod Associations from the Lower Miocene of the Most Basin in Northern Bohemia(Czech Republic):A Preliminary Report

    Institute of Scientific and Technical Information of China (English)

    Jakub PROKOP; Torsten WAPPLER; Stanislav KNOR; Zlatko KVA(C)EK

    2010-01-01

    Terrestrial plants and insects currently account for the majority of the Earth's biodiversity,and approximately half of insect species are herbivores.Thus,insects and plants share ancient associations that date back more than 400 Myr.However,investigations of their past interactions are at the preliminary stages in Western Europe.Herein,we present the first results of our study of various feeding damage based on a dataset of nearly 3500 examined plant specimens from the Lower Miocene of the Lagerstatte Bilina Mine in the Most Basin,Czech Republic.This site provides a unique view of the Neogcue freshwater ecosystems.It has long been studied by scientists working in different branches of sedimentology,paleobotany,and paleozoology.The fossils are preserved in three characteristic horizons overlaying the coal seam(Clayey Superseam Horizon,Delta Sandy Horizon,and Lake Clayey Horizon),reflecting paleoenvironmental changes in a short time period of development.The trace fossils are classified as functional feeding groups or"guilds",without searching for a direct cause or a recent analog host relation.Approximately 23% of specimens of dicotyledonous plant leaves were found to be damaged and associated with some leaf"morphotypes".Deciduous plant-host taxa,and those with a chartaceons texture typical of riparian habitats,were frequently damaged,such as Populus,recorded with two species Populus zaddachii and Populus populina(57.9% and 31% herbivory levels,respectively),followed by Acer,Alnus,and Carya,averaging almost 30% of damaged leaves/leaflets.There has been evidence of 60 damage types(DT)representing all functional feeding groups recorded at the Bilina Mine,including 12 types of leaf mines and 16 galltype DT.In total,Lower Miocene of the Lagerstatte Bilina Mine exhibits a high level of external foliage feeding types(23.7%),and a low level of more specialized DT,such as galls(4.3%)and leaf mines(<1%).A broader comparison based on DT of the main sedimentary environments

  9. Geochemical correlation of oil from the Ayoluengo field to Liassic black shale units in the southwestern Basque-Cantabrian Basin (northern Spain)

    Energy Technology Data Exchange (ETDEWEB)

    Quesada, Santiago; Robles, Sergio [University of the Basque Country, Stratigraphy and Paleontology Dept., Bilbao (Spain); Dorronsoro, Carmen [University of the Basque Country, Geology Dept., Bilbao (Spain); Chaler, Roser; Grimalt, Joan O. [C.I.D.-C.S.I.C., Environmental Chemistry Dept., Barcelona (Spain)

    1997-12-31

    A study of the Liassic sequence in the Basque-Cantabrian Basin has shown the presence of organic-rich (TOC, HI and S{sub 2} up to 8.7%, 760 and 56.5 mg/g, respectively) Pliensbachian-early Toarcian black shales that constitute the only feasible source rock for Ayoluengo oil. The stratigraphical and sedimentological data show that these black shales developed into a major transgressive sequence of hemipelagic Lotharingian-Toarcian facies, which suggests the presence of anoxic or near anoxic bottom water conditions in troughs during their deposition. The {delta}{sup 13}C composition, and a detailed study of the linear, branched, isoprenoid, steroid and hopanoid aliphatic hydrocarbons in these shales, marls and the Ayoluengo oil confirms this hypothesis. Specifically, the {delta}{sup 13}C values of the total solvent extract of the thicker shale (No. 2) and the oil are -29.93 and -29.88``per mille``, respectively; also a close similarity in the relative compositions of steranes and hopanes is observed between these samples. The distributions of these compounds exhibit several distinct features. The steranes in this shale and crude oil are characterized by a depletion of C{sub 28} vs C{sub 27} and C{sub 29} homologues (24 vs 32 and 44%, respectively), which is consistent with the carbon number sterane distributions generally observed among Upper Paleozoic to Liassic rock-sourced oils. Furthermore, hopanes and steranes are characterized by their high relative content of rearranged molecules. Diasteranes (13{beta}(H),17{alpha}(H)- and 13{alpha}(H),17{beta}(H)- series) are the dominant compounds among the steranes and significant amounts of 18{alpha}(H)-17{alpha}methyl-28-norhopanes (C{sub 27}, C{sub 29} and C{sub 30} homologues) and 17{alpha}(H)-15{alpha}-methyl- 27 norhopanes (C{sub 30} homologue) are found in the hopanoid hydrocarbons. Conversely, the proportion of these rearranged molecules in other sediment samples from the same formation decrease with increasing

  10. Magnetostratigraphic study of a continental succession in the Alessandria Basin: contribution to the chronological reconstruction of the Pliocene-Pleistocene transition in Northern Italy.

    Science.gov (United States)

    Tema, Evdokia; Irace, Andrea; Monegato, Giovanni; Martinetto, Edoardo; Gianolla, Daniele; Pini, Roberta

    2013-04-01

    In this work we present the results of a detailed magnetostratigraphic study carried out on fine-grained lenses of a fluvial succession, exposed in the southern border of the Alessandria Basin (NW Italy), of Plio-Quaternary age. The studied succession mainly consists of coarse sands and gravels. Several fine-grained lenses, related to abandoned channels, also occur. For palaeomagnetic analyses, five laminated clayey and silty lenses were sampled, following a systematic 5-10 cm sampling interval. All samples were oriented in situ using a magnetic compass and an inclinometer. Isothermal remanent magnetization measurements show that for most of the samples saturation is reached at low applied fields, varying from 0.3 to 0.4 T, indicating the presence of a low-coercivity mineral such as magnetite. No systematic variation of the magnetic properties along the whole section has been registered, except for samples coming 8.5 to 10 m from the base of the fluvial succession, where the presence of sulphurs such as greigite has been identified. All samples were systematically stepwise demagnetized in alternating field (AF) following 7 to 9 steps in the range 5 to 80 mT. AF demagnetizations show that in most cases the NRM consists of a soft, low-coercivity component erased at around 10-15 mT, probably of viscous origin, and a more stable component isolated from 15 to 60 mT that can be confidently considered as the Characteristic Remanent Magnetization (ChRM). Interpretation of the demagnetization results based on principal component analysis shows a polarity reversal for the upper part of the section, while the lower part of the section is characterized by normal polarities. The results from the part of the section where the presence of greigite has been identified have not been taken into consideration as they may be unreliable due to remagnetization procedures. The obtained palaeomagnetic data, combined with stratigraphic and biostratigraphic evidences, suggest that the

  11. New morpho-stratigraphic constraints for the evolution of the alluvial fan system along the northern slopes of the Taburno-Camposauro Mountains (Calore River basin, Southern Italy)

    Science.gov (United States)

    Leone, Natalia; Amato, Vincenzo; Aucelli, Pietro P. C.; Cesarano, Massimo; Filocamo, Francesca; Petrosino, Paola; Rosskopf, Carmen M.; Valente, Ettore; Giralt, Santiago; Casciello, Emilio

    2016-04-01

    The Lower Calore River Valley is a morphostructural depression located in the inner sector of the Campanian Apennine, between the Taburno-Camposauro and the Matese carbonate massifs. The river is the main left tributary of the Volturno River, it has a meandering channel partially structural-controlled. Numerous morphotectonic clues and historical seismicity data suggest that this part of the Apennine chain was particularly active during the late-Quaternary. In detail, the valley is E-W oriented and presents an asymmetry of the opposed valley slopes. The left side, corresponding to the northern flank of the Camposauro massif, is characterized by a steep slope (70°-35°), partially controlled by a ~E-W oriented fault system, and by a wide less-inclined piedmont aggradation zone. The latter started growing since middle Pleistocene, with the deposition of alluvial fans and slope deposits over the well cemented early Pleistocene breccias of Laiano Synthem. The alluvial fan deposition has been active until present giving rise to three main generations of alluvial fans. The right side of the valley, instead, is characterized by seven orders of fluvial terraces, both of erosional and depositional origin. The quaternary morpho-stratigraphic evolution of alluvial fans and fluvial terraces has been strongly conditioned by the interaction of tectonic phases and climatic variations. A detailed geomorphological study (1:5.000 in scale) was carried out with the aim to map the main depositional and erosional fluvial landforms and to identify the main tectonic lineaments of the area. A detailed field survey allowed to better define the stratigraphic and paleoenvironmental context in which the alluvial deposits developed and also to find chrono-stratigraphic markers. Tephra-stratigraphic analyses were performed on pyroclastic deposits interbedded into the alluvial fan and fluvial successions. At the moment the age of the first generation of alluvial fans is still under

  12. Multi-method provenance model for early Paleozoic sedimentary basins of southern Peru and northern Bolivia (13°-18°S)

    Science.gov (United States)

    Reimann Zumsprekel, Cornelia R.; Bahlburg, Heinrich; Carlotto, Victor; Boekhout, Flora; Berndt, Jasper; Lopez, Shirley

    2015-12-01

    In early Paleozoic time the Peru-Bolivia Trough at the South American Gondwana margin accommodated large volumes of siliciclastic detritus of hitherto largely unknown provenance. A multi-method provenance study of framework components, heavy minerals and whole rock geochemistry of Ordovician to Devonian formations of southern Peru and northern Bolivia reveals the predominant contribution from upper crustal sources. Main heavy minerals include zircon, tourmaline, rutile, apatite, garnet, epidote, monazite, and titanite and are strongly biased diagenetically towards the stable phases. Electron microprobe single grain analysis of tourmaline and rutile indicate that detrital tourmalines were derived mainly from metasedimentary, and subordinately, from granitic sources. Cr/Nb ratios in rutiles point to a metamafic derivation for 20-40% of grains, the remainder originating in felsic lithologies. Zr in rutile thermometry indicates a provenance from relatively high-grade metamorphic rocks transformed at temperatures between 500 °C and 900 °C, with clusters at c. 600 °C, 700 °C and 800 °C. U-Pb geochronological analysis of rutiles was largely unsuccessful due to high concentrations of common Pb. Three ages could be obtained and fall between 525 and 545 Ma, probably linking this detritus to the hidden Neoproterozoic orogen in what are now Cordillera Oriental and Sierras Subandinas. The most notable feature of the whole rock geochemical data is a high Cr content in the majority of samples, which otherwise have a composition similar to weathered upper continental crust. The elevated Cr contents indicates that ophiolitic rocks were either exposed to erosion abundantly in the source areas or had previously supplied significant volumes of detritus to intermittent sediment storage systems now eroded into the studied sedimentary rocks. Potential source candidates include the Ordovician metamorphic Tapo Ultramafic Complex in the Cordillera Oriental of central Peru, and the

  13. Integrated provenance analysis of a convergent retroarc foreland system: U-Pb ages, heavy minerals, Nd isotopes, and sandstone compositions of the Middle Magdalena Valley basin, northern Andes, Colombia

    Science.gov (United States)

    Nie, Junsheng; Horton, Brian K.; Saylor, Joel E.; Mora, Andrés; Mange, Maria; Garzione, Carmala N.; Basu, Asish; Moreno, Christopher J.; Caballero, Victor; Parra, Mauricio

    2012-01-01

    Sediment provenance analysis remains a powerful method for testing hypotheses on the temporal and spatial evolution of uplifted source regions, but issues such as recycling, nonunique sources, and pre- and post-depositional modifications may complicate interpretation of results from individual provenance techniques. Convergent retroarc systems commonly contain sediment sources that are sufficiently diverse (continental magmatic arc, fold-thrust belt, and stable craton) to enable explicit provenance assessments. In this paper, we combine detrital zircon U-Pb geochronology, heavy mineral identification, Nd isotopic analyses, conventional sandstone petrography, and paleocurrent measurements to reconstruct the clastic provenance history of a long-lived sedimentary basin now exposed in an intermontane zone of the northern Andean hinterland of Colombia. The Middle Magdalena Valley basin, situated between the Central Cordillera and Eastern Cordillera, contains a 5-10 km-thick succession of Upper Cretaceous to Quaternary fill. The integrated techniques show a pronounced change in provenance during the Paleocene transition from the lower to upper Lisama Formation. We interpret this as a shift from an eastern cratonic source to a western Andean source composed of magmatic-arc rocks uplifted during initial shortening of the Central Cordillera. The appearance of detrital chloritoid and a shift to more negative ɛ Nd(t=0) values in middle Eocene strata of the middle La Paz Formation are attributed to shortening-related exhumation of a continental basement block (La Cira-Infantas paleohigh), now buried, along the axis of the Magdalena Valley. The diverse provenance proxies also show distinct changes during middle to late Eocene deposition of the Esmeraldas Formation that likely reflect initial rock uplift and exhumation of the fold-thrust belt defining the Eastern Cordillera. Upsection, detrital zircon U-Pb ages and heavy mineral assemblages for Oligocene and younger clastic

  14. 塔里木盆地北缘英岗地区铀成矿特征及找矿远景%Uranium Metallogenic Characteristics and Prospecting Prospective of Yinggang area of the Northern Tarim Basin

    Institute of Scientific and Technical Information of China (English)

    李炎龙; 邬力生; 王国荣

    2016-01-01

    英岗地区位于塔里木盆地柯坪断隆,属塔里木北缘铀成矿带,区内含铀及富铀层众多,为铀矿化的形成提供了重要的物质来源。结合区域铀矿勘查成果,对区域地质背景、地质特征、铀成矿特征进行了详细分析,并划分了成矿远景区。研究结果表明:①英岗地区上石炭统康克林组具备铀资源找矿前景,初步确定其铀成矿类型为古层间氧化带型;②英岗地区上石炭统康克林组铀成矿可分为3个阶段,即晚石炭世铀初始富集阶段、早二叠世铀叠加富集阶段和新生代强烈构造改造阶段。上述分析成果对于该区今后铀矿找矿工作有一定的参考价值。%Yinggang area is located in Kalpin fault uplift of Tarim basin,it belongs to the uranium metallogenic belt of the northern Tarim basin,many uranium layers and rich uranium layers are distributed in Yinggang area,they area provide the important material resources of the formation of uranium minerali-zation.Based on the prospecting results of the uranium deposits in Yanggang area,the regional geological background,geological characteristics of the area,uranium metallogenic characteristics area analyzed,be-sides that the prospect areas are delineated.The study results show that:①the prospecting prospective of uranium deposit of upper carboniferous Kangkelin formation of Yinggang area is good,the uranium metal-logenic type of upper carboniferous Kangkelin formation is determined as inter -layer oxidation zone type;②the uranium metallogenic of upper carboniferous Kangkelin formation of Yinggang are can be di-vided into three stages,they are the initial enrichment stage of uranium in late carboniferous epoch,super-position enrichment stage of uranium in early permian epoch and strong tectonic reworking stage in ceno-zoic.The above study results can provide some reference for the uranium deposit prospecting work in Yinggang area.

  15. Petrogenesis and geodynamics of plagiogranites from Central Turkey (Ekecikdağ/Aksaray): new geochemical and isotopic data for generation in an arc basin system within the northern branch of Neotethys

    Science.gov (United States)

    Köksal, Serhat; Toksoy-Köksal, Fatma; Göncüoglu, M. Cemal

    2016-09-01

    In the Late Cretaceous, throughout the closure of the Neotethys Ocean, ophiolitic rocks from the İzmir-Ankara-Erzincan ocean branch were overthrusted the northern margin of the Tauride-Anatolide Platform. The ophiolitic rocks in the Ekecikdaǧ (Aksaray/Central Turkey) region typify the oceanic crust of the İzmir-Ankara-Erzincan branch of Neotethys. The gabbros in the area are cut by copious plagiogranite dykes, and both rock units are intruded by mafic dykes. The plagiogranites are leucocratic, fine- to medium-grained calc-alkaline rocks characterized mainly by plagioclase and quartz, with minor amounts of biotite, hornblende and clinopyroxene, and accessory phases of zircon, titanite, apatite and opaque minerals. They are tonalite and trondhjemite in composition with high SiO2 (69.9-75.9 wt%) and exceptionally low K2O (<0.5 wt%) contents. The plagiogranites in common with gabbros and mafic dykes show high large-ion lithophile elements/high-field strength element ratios with depletion in Nb, Ti and light rare-earth elements with respect to N-MORB. The plagiogranites together with gabbros and mafic dykes show low initial 87Sr/86Sr ratios (0.70419-0.70647), high ƐNd(T) (6.0-7.5) values with 206Pb/204Pb (18.199-18.581), 207Pb/204Pb (15.571-15.639) and 208Pb/204Pb (38.292-38.605) ratios indicating a depleted mantle source modified with a subduction component. They show similar isotopic characteristics to the other supra-subduction zone (SSZ) ophiolites in the Eastern Mediterranean to East Anatolian-Lesser Caucasus and Iran regions. It is suggested that the Ekecikdaǧ plagiogranite was generated in a short time interval from a depleted mantle source in a SSZ/fore-arc basin setting, and its nature was further modified by a subduction component during intra-oceanic subduction.

  16. Nuevos registros de ofiuroideos (Echinodermata: Ophiuroidea para localidades de Zihuatanejo (Guerrero y Puerto Escondido (Oaxaca, Pacífico mexicano New records of ophiuroids (Echinodermata: Ophiuroidea from localities at Zihuatanejo (Guerrero and Puerto Escondido (Oaxaca, Mexican Pacific

    Directory of Open Access Journals (Sweden)

    M. Rebeca Granja-Fernández

    2011-12-01

    Full Text Available Se presentan nuevos registros de ofiuroideos para localidades de Zihuatanejo, Guerrero y de Puerto Escondido, Oaxaca en el Pacífico mexicano. Mediante recolectas realizadas en diversos sustratos se obtuvieron 12 especies, de las cuales Ophiocoma alexandri Lyman, 1860 y Ophiothela mirabilis (Verrill, 1867 fueron las más ampliamente distribuidas. Este número de especies, el más alto registrado respecto a trabajos previos, se atribuye a la mayor amplitud espacial del esfuerzo de muestreo y a la mayor diversidad de sustratos explorados. Se dan a conocer nuevos sustratos habitados por O. mirabilis y Ophioderma panamensis Lütken, 1859. Se presenta el primer registro de asociación de un organismo juvenil de O. alexandri con un hidrozoo del orden Leptothecata en el Pacífico oriental. A pesar del incremento en el número de especies reconocidas para las localidades, se sugiere llevar a cabo una prospección más amplia del Pacífico tropical mexicano y un mayor esfuerzo de muestreo en diversos sustratos con el fin de incrementar el conocimiento de la biodiversidad de ofiuros en la zona.New records of ophiuroids from localities at Zihuatanejo, Guerrero and Puerto Escondido, Oaxaca in the Mexican Pacific are presented. Based on specimens collected on diverse substrata, 12 species were identified; Ophiocoma alexandri Lyman, 1860 and Ophiothela mirabilis (Verrill, 1867 being the most widely distributed. The larger number of recorded species compared to previous studies may result from a spatially broader sampling and a more thorough survey involving a larger variety of substrata. New substrata for O. mirabilis and Ophioderma panamensis Lütken, 1859 are reported. We document, for first time, the relationship between a juvenile of O. alexandri and a hydrozoan of the order Leptothecata in the Eastern Pacific. Although this paper documents a significant increase in the number of recorded species in the study area, we highlight the need for a large scale

  17. Northern employment

    International Nuclear Information System (INIS)

    Hiring practices and policies and employment opportunities that were available in the Beaufort Sea and MacKenzie Delta project for local residents and for people from southern Canada were dealt with in this chapter. Depending on the source, Northern hiring was a mere token, or a genuine and successful effort on the part of the companies to involve the native population and to share with them the benefits of the project. The fact remains that opening up job opportunities for Northerners was not easily attained, and would never have been realized without the involvement of government and community organizations. Government also played a major role in developing policies and training regimes. By the end of exploration operations, the hiring of Northern residents in the oil and gas industry had become a requirement of drilling applications. Training programs were also created to ensure that Northern residents received the means necessary to take advantage of Northern employment opportunities

  18. Source characteristics of moderate size events using empirical Green funclions: an application to some Guerrero (Mexico subduction zone earthquakes

    Directory of Open Access Journals (Sweden)

    S. K. Singh

    1994-06-01

    Full Text Available The records of an aftershock (M ~ 4 of a moderate size event (M = 5.9 which occurred along the subduction zone of Guerrero (Mexico, are used as empirical Green functions (EGF to determine the source characteristics of the mainshock and of its smaller size (M = 5.5 foreshock. The data consist of accelerograms recorded by the Guerrero Accelerograph Array, a high dynamic range strong motion array. The three events appear to be located close to each other at distances much smaller than the source to receiver distances. The fault mechanism of the mainshock is computed by non-linear inversion of P polarity readings and S wave polarizations determined at two near source stations. The foreshock and aftershock fault mechanisms are similar to that of the mainshock as inferred from long period data and shear wave polarization analysis. The maximum likelihood solution is well constrained, indicating a typical shallow dipping thrust fault mechanism, with the P-axis approximately oriented in a SSW direction. The source time functions (STFs of the mainshock and foreshock events are determined using a new method of deconvolution of the EGF records at three strong motion sites. In this method the STF of the large event is approximated by a superposition of pseudo triangular pulses whose parameters are determined by a non-linear inversion in frequency domain. The source time function of the mainshock shows the presence of two separate pulses, which can be related to multiple rupture episodes. The relative location of mainshock sub-events is done by using plots of isochrones computed from measurementes of the time delay between pulses on the STF records at each station. The first sub-event is located no more than 2.5-3 km away from the other along the fault strike. The STF retrieved from foreshock records shows single pulse waveforms. The computed STFs are used to estimate seismic moments, source radii and stress release of the events assuming a circular fault

  19. Factores de éxito emprendedor en dos municipios de la montaña de Guerrero, México

    Directory of Open Access Journals (Sweden)

    Juan Morales-Jiménez

    2015-01-01

    Full Text Available El Objetivo del trabajo fue identificar la motivación para el emprendimiento y los factores del éxito competitivo de los emprendedores de pequeños negocios que se ubican en la Montaña de Guerrero, México. Se aplicó un cuestionario con preguntas cerradas, con una escala de tipo Likert, con variables de los factores económicos, psicológicos, sociales y culturales para identificar diferencias de emprendimiento y del éxito competitivo. Estas diferencias fueron medidas con base en la importancia que el dueño le asignó a las acciones de desarrollo del negocio. Con la prueba de U de Mann-Whitney se evaluó estadísticamente si había diferencias en el éxito competitivo entre los municipios de Huamuxtitlán y Metlatónoc. Los resultados indicaron que la mayoría de los emprendedores son jóvenes y en su mayoría son mujeres, quienes inician la microempresa con ahorros propios y predomina en su operación la informalidad. El factor económico de motivación para emprender una microempresa o negocio fue la mejora en el ingreso. El principal factor psicológico fue la confianza en el éxito del negocio, siendo importante la motivación del o la conyugue. El factor social fue el desempleo y el factor espacial fue la buena ubicación del negocio. Al comparar entre municipios, se encontró diferencia estadística significativa entre ellos (p ≤ 0.001 para todos los factores evaluados. El análisis de regresión logística binaria indicó que las variables de mayor peso para la consolidación o éxito de las empresas de los emprendedores de la Montaña de Guerrero son la edad, la escolaridad y el lugar donde estén ubicados.

  20. MICROFLORA CULTIVABLE Y ENDOMICORRIZAS OBTENIDAS EN HOJARASCA DE BOSQUE (PÁRAMO GUERRERO FINCA PUENTE DE TIERRA ZIPAQUIRÁ, COLOMBIA Cultivable Microflora and Endomycorrhizas Obtained in Litter Forest (Paramo Guerrero Finca Puente de Tierra Zipaquirá, Colombia

    Directory of Open Access Journals (Sweden)

    ELEONORA BERNAL

    2006-06-01

    Full Text Available Se realizó el recuento de microorganismos cultivables (bacterias y hongos, microorganismos celulolíticos y endomicorrizas presentes en la hojarasca de bosque (finca Puente de Tierra en el páramo Guerrero, Colombia. Los microorganismos aislados con mayor frecuencia pertenecían a los géneros Staphylococcus, Bacillus, Pseudomonas, Micrococcus, Penicillium, Rhodotorula y se aisló una cepa de Cladosporium sp. en un medio selectivo con carboximetil celulosa. Así mismo, se encontraron ocho morfotipos de endomicorrizas, entre los cuales predominaron especies de Glomus y Acaulospora. Este estudio contribuye con el conocimiento de la microbiota cultivable de hojarasca, que ha sido poco explorada en ecosistemas de páramo.The count of cultivable microorganisms (bacteria and fungi, cellulolytic microorganisms and endomycorrhizas present in litter forest (property Puente de Tierra in the Guerrero’s moor, Colombia was made. The most frequently isolated microorganisms belonged to the Staphylococcus, Bacillus, Pseudomonas, Micrococcus, Penicillium and Rhodotorula genus and Cladosporium sp., which is a cellulolytic microorganism, was isolated in carboxymethyl cellulose agar. In addition eight morphotypes of endomycorrhizas were found, species of Glomus and Acaulospora predominated among them. This study contributes with the knowledge of the cultivable microorganisms of litter that have been little explored in moor ecosystems.

  1. High resolution sequence stratigraphy and reservoir prediction of northern Wuerxun Sag, the Hailar Basin%海拉尔盆地乌尔逊凹陷北部高分辨率层序地层与储层预测

    Institute of Scientific and Technical Information of China (English)

    秦雁群; 邓宏文; 侯秀林; 杨金秀; 季春辉; 刘璐

    2011-01-01

    海拉尔盆地乌尔逊凹陷北部断裂复杂,沉积成因类型多,油藏类型认识不清.应用高分辨率层序地层学原理和分析方法,以岩心、测井、地震资料为基础,通过研究区主要含油层段(南屯组二段、大磨拐河组一段)层序地层关键界面的识别与对比,逐级控制,建立了盆地高分辨率层序格架.研究表明,乌尔逊凹陷北部苏131、苏102断块油藏产油层段跨越两个三级层序界面,主要产油层段位于大磨拐河组一段三级层序底部,主要储层为低位域滑塌浊积岩储集体,而不是此前认为的南屯组二段三级层序顶部的扇三角洲前缘砂体.通过对研究区主要产油层段的层序地层位置重新厘定与对储集体成因类型详细分析,提出了乌尔逊凹陷北部地区油藏类型应该为构造-岩性油气藏的新认识,并分析了砂层组的时空展布特征,为该油田深入开发与扩边提供了依据.%The reservoir types are unclear in the northern Wuerxun Sag, the Hailar Basin, due to the complex fractures and various sedimentary genetic types. Based on the core, seismic and logging data, a high resolution sequence framework was established through the identification and comparison of key boundaries of the main oil-bearing formations, I. E. The second member of Nantun Formation (K1n2) and the first member of Damoguaihe Formation (K1d1). The pay zones cross two third-order sequence boundaries in the Su 131 and Su 102 fault-block reservoirs. The main reservoir is the low-system-tract slumped turbidite located at the bottom of the third-order sequence instead of the fan-delta front sand body located at the top of third-order sequence. Based on redefinition of the sequence-stratigraphic position of the main pay zone and analysis of reservoir genetic types, it is proposed that the reservoir in the northern Wuerxun Sag is of structural-lithologic type. In addition, the temporal and spatial distribution of sand units is

  2. A mineralogical record of brine evolution and environmental change from Da Qaidam Salt Lake in the northern Qaidam Basin%大柴旦盐湖卤水演变及环境变化的矿物学记录

    Institute of Scientific and Technical Information of China (English)

    高春亮; 张丽莎; 余俊清; 成艾颖; 刘永

    2011-01-01

    大柴旦盐湖因蕴藏同体和液体硼矿资源成为柴达木盆地诸多盐湖中最早被关注和开发的盐湖之一.然而,对其常年水体底部沉积剖面的相关研究工作却几乎没有开展.报道了该盐湖中央湖底硼矿层以上连续沉积剖面的加速器质谱计(AMS) 14C年代学和矿物学研究结果,首次揭示湖底硼矿层形成于约3600 a BP之前;剖面的岩性与矿物组成标示了晚全新世以来该盐湖水化学演化的3个主要阶段;受降水量主控的入湖径流量决定了盐湖水位和卤水水化学的阶段性演化特征,以及各阶段中十年级和百年级的水化学变动.研究结果为探讨柴达木盆地北部晚全新世以来水文气候的演变历史提供了代理记录.%Da Qaidam Salt Lake is known for its both liquid and solid boron resource. The exploitation of the boron deposits and related geological studies started since 1950s. Little attention has been paid, however, to the study of sedimentary records from the salt lake as regarding to brine evolution and environmental change. Here we report the result of AMS 14C dating and mineralogical investigation on a subbottom sediment section from the central area of the saline water-body. The result reveals that the subbottom pinnoite deposit was formed before 3600 a BP, and that the lake underwent three stages of lake-levels and brine evolution in the late Holocene, which were determined mainly by precipitation-controlled catchment inflow. The mineralogical records also depict fluctuations in lake-levels and water chemistry on decadal and centennial scales. The data provide a proxy record for the reconstruction of the late-Holocene hydro-climate change on the northern Qaidam Basin.

  3. Development of a System-wide Predator Control Program: Stepwise Implementation of a Predation Index, Predator Control Fisheries, and Evaluation Plan in the Columbia River Basin; Northern Pikeminnow Management Program, 1998 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Young, Franklin R.; Wachtel, Mark L.; Petersen, Marc R.

    2003-03-01

    We are reporting on the progress of the Northern Pikeminnow Sport-Reward Fishery (NPSRF) in the lower Columbia and Snake rivers for 1998. The objectives of this project were to (1) implement a sport fishery that rewards anglers who harvest northern pikeminnow Ptychocheilus oregonensis {ge}279 mm (11 inches) total length, (2) collect catch data on selected fish species caught by fishery participants while targeting northern pikeminnow, (3) monitor and report incidental catch of sensitive salmonid species by anglers targeting northern pikeminnow and, (4) collect, monitor and report data on angler participation, catch and catch per angler day of northern pikeminnow during the season. A total of 108,903 northern pikeminnow {ge}279 mm were harvested during the 1998 season and 21,959 angler days were spent harvesting these fish. Harvest was below the seven year average of 150,874 and participation was well below the seven-year average of 51,013 angler days. Catch per angler day for all anglers during the season was 4.96 and exceeded the seven-year average of 2.96 northern pikeminnow per angler day. Peamouth Mylocheilus caurinus, and white sturgeon Acipencer transmontanus, were the other species most often harvested by returning NPSRF anglers targeting northern pikeminnow. Harvest of salmonids Oncorhynchus spp. by NPSRF anglers targeting northern pikeminnow remained below limits established by the National Marine Fisheries Service (NMFS).

  4. Coal quality in the northern Appalachian Basin

    Energy Technology Data Exchange (ETDEWEB)

    Bragg, L.J.; Tewalt, S.J.; Ruppert, L.F.; Wallack, R.N. [Geological Survey, Reston, VA (United States)

    1998-12-31

    The national coal resource assessment, being conducted by the US Geological Survey (USGS), provides information on both the quantity and quality of the coal beds and zones of the coals that are expected to provide most of the coal utilized in the US during the next few decades. As part of this assessment, the USGS developed comprehensive geochemical databases for the Pittsburgh and the Upper Freeport coal beds, which are then used to map and model trends in the ash yield, sulfur (S) content, and calorific value of the coals, as well as trends in selected major-, minor-, and trace- element contents. Compilation of the databases, mapping of geochemical trends, and comparisons of the trends and mean values for ash yield, S content, calorific value (Btu/lb), arsenic (As) content, selenium (Se) content, mercury (Hg) content, and chlorine (Cl) content for these beds are discussed in the paper. Final results for the complete database are presented for the Pittsburgh coal bed. Preliminary results for ash yield, S content and calorific value are presented for the Upper Freeport coal bed.

  5. Violencia física intrafamiliar contra la embarazada: un estudio con base poblacional en Ometepec, Guerrero, México Violence during pregnancy: a population based study in Ometepec, Guerrero, Mexico

    Directory of Open Access Journals (Sweden)

    Sergio Paredes-Solís

    2005-10-01

    Full Text Available OBJETIVO: Estimar la ocurrencia de la violencia física intrafamiliar contra la embarazada, factores asociados y percepción de daños a la salud, en un estudio con base poblacional. MATERIAL Y MÉTODOS: Un grupo de enfermeras aplicó, una encuesta en cada hogar de Ometepec, Guerrero, México, a las mujeres que notificaron al menos un embarazo en los tres años previos a la encuesta. RESULTADOS: Se realizó una entrevista a 2 389 mujeres, de las cuales 709 fueron elegibles para completar el cuestionario sobre el último embarazo. Entre mujeres cuyo esposo no estuvo presente en el momento de la entrevista, 21% declaró ser víctima de violencia física y 5.6% reportó maltrato físico intrafamiliar durante el último embarazo. Se encontró una asociación entre violencia física en la embarazada y sangrado transvaginal durante el embarazo. La asociación entre violencia física y pérdida del embarazo tuvo significancia estadística marginal (p=0.06. También hubo asociación entre ser objeto de violencia física durante el embarazo y una actitud violenta hacia los hijos, bajo un escenario hipotético de rebeldía por parte de los mismos. CONCLUSIONES: Un hallazgo importante es la asociación entre problemas obstétricos durante el embarazo y la violencia física.OBJECTIVE: The occurrence of physical abuse during pregnancy, identifying associated factors and outcomes for women's health was estimated. MATERIAL AND METHODS: A cross-sectional community-based study in Ometepec in the Mexican state of Guerrero identified women who reported at least one pregnancy in the three years prior to the survey. These completed a questionnaire administered by a female nurse. RESULTS: Out of 2 389 women in Ometepec, 709 were eligible to complete the questionnaire. Among those interviewed without being present their partners/husbands, 21% reported a history of physical abuse and 5.6% reported physical abuse during the last pregnancy. There was a strong association

  6. Ecología reproductiva del bobo café (Sula leucogaster en Morros El Potosí, Guerrero, México Reproductive ecology of Brown Boobies (Sula leucogaster at Morros El Potosí, Guerrero, Mexico

    Directory of Open Access Journals (Sweden)

    Juan Pablo Ceyca

    2009-12-01

    Full Text Available Entre enero y junio de 2006 se estudió la ecología reproductiva del bobo café (Sula leucogaster en Morros El Potosí, Guerrero. Determinamos parámetros reproductivos, profundidad máxima de buceo, duración de viajes de forrajeo y porcentaje de atención al nido. Los bobos cafés anidaron durante gran parte del año y exhibieron 2 picos reproductivos: otoño y primavera. Durante este último, el éxito de eclosión fue 61%. Estimamos densidades de 1 300 nidos/ha en la ladera y de 2 000 nidos/ha en la cima de la isla. No observamos depredación, pero condiciones meteorológicas adversas causaron pérdida de huevos y muerte de pollos. Los viajes de forrajeo más largos (5.78 ± 0.21 h y los buceos más profundos (5.52 ± 0.42 m en Morros El Potosí que en otras colonias, sugirieron que los bobos cafés requirieron aquí un mayor esfuerzo de forrajeo, quizás por estar en aguas más calientes, con menos recursos. Los bobos cafés hembra atendieron por más tiempo los nidos con huevos o con pollos que los machos. No hubo diferencias en el tiempo de presencia de los padres en el nido entre meses, lo que, aunado a la variación en la duración de los viajes de forrajeo entre meses, sugiere que hubo fluctuaciones de corta duración en la disponibilidad de alimento durante el periodo de estudio.We studied the breeding ecology of Brown Boobies (Sula leucogaster at Morros El Potosí, Guerrero, between January and June 2006. We determined breeding parameters, foraging habits, and patterns of parental care, and evaluated their effects upon breeding success. Brown Boobies nested during a great part of the year, and exhibited 2 breeding peaks: Fall and Spring. During the later, hatching success was 61%. We estimated 1 300 nests/ha on the slope of the island, and 2 000 nests/ha on the top. We did not record predation, but adverse meteorological conditions caused the loss of eggs and chicks. The longer foraging trips (5.78 ± 0.21 h and deeper diving (5

  7. Cruzas intervarietales de maíz para la región semicálida de Guerrero, México Intervarietal maize crosses for the semi-warm region of Guerrero, México

    Directory of Open Access Journals (Sweden)

    Francisco Palemón Alberto

    2011-10-01

    Full Text Available La orografía y agroecología del estado de Guerrero es muy diversa y en las áreas agrícolas de altitud intermedia (1 200 a 1 700 m, prácticamente no se siembran variedades mejoradas, debido a condiciones climáticas y edáficas poco favorables, por lo que dificulta establecer un programa de mejoramiento genético de maíz para cada nicho ecológico. En estas regiones se examinó la estabilidad de 25 variedades de maíz, durante cinco ciclos agrícolas verano-otoño de 2005 a 2009; con el propósito de identificar una cruza intervarietal estable, consistente y con buen potencial de rendimiento a través de ambientes. La información se analizó en 20 variedades, usando un diseño de bloques completos al azar con tres repeticiones por localidad y combinando localidades. Con esta información se estimó los parámetros de estabilidad propuestos por Eberhart y Russell y descritos por Molina; además se aplicó el modelo de efectos principales aditivos e interacción multiplicativa (AMMI. Los progenitores masculinos V15 y V16 mostraron estabilidad y consistencia a través de ambientes; similar comportamiento mostraron las cruzas intervarietales V3, V7 y V9, además fueron sobresalientes en rendimiento de grano; V11 fue consistente y mostró mayor potencial productivo en ambientes desfavorables. Las cruzas intervarietales V1, V4, V6, V10, la variedad local del agricultor V13 y los progenitores femeninos V17, V18 y V20, mostraron buena respuesta en ambientes favorables pero fueron inconsistentes. Los dos métodos usados registraron resultados semejantes, por lo que fue posible seleccionar tres variedades por su potencial de rendimiento de grano, estabilidad y consistencia en los ambientes.The topography and agro-ecology of the Guerrero State is diverse and in agricultural areas of intermediate elevation (1 200 to 1 700 m, almost no improved varieties are planted, due to unfavorable climatic and soil conditions, so it is difficult to establish a

  8. Bases para una teoría del pluralismo jurídico : El reconocimiento del derecho indígena en Guerrero, México

    OpenAIRE

    Morales Sánchez, Joaquín

    2013-01-01

    El planteamiento que engloba esta investigación, se circunscribe al derecho a la libre determinación expresada en la autonomía para aplicar los sistemas normativos (derecho) de los pueblos indígenas del Estado de Guerrero, el cual se hace latente cada vez más, a tal grado de provocar tensión con el sistema jurídico oficial. Ante esta problemática, el objetivo general de esta tesis estriba en experimentar una posibilidad para la coexistencia formal entre estos fenómenos jurídicos. En este...

  9. La participación campesina en los procesos de desarrollo en la montaña de Guerrero: El caso del grupo de autoayuda "Tlalixtaquilla".

    OpenAIRE

    López Pérez, Arnulfo

    2012-01-01

    El presente trabajo evaluó la percepción de los participantes en el funcionamiento y crecimiento del fondo de ahorro del grupo de autoayuda “Tlalixtaquilla” en la Región Montaña en Guerrero. Se aplicaron 68 entrevistas de un total de 94 participantes del grupo y se analizaron los registros de los estados de cuenta durante la operación del grupo (2006 - 2010). La guía de entrevista consideró información de los participantes, la operación y funcionamiento del fondo de ahorro y de la continuid...

  10. Sistemas de producción tradicional de maíz, cebolla y frijol de mata practicados en Copanatoyac, Guerrero.

    OpenAIRE

    Rosendo Rosendo, Gil Andrés

    2012-01-01

    La presente investigación se desarrolló en seis localidades del municipio de Copanatoyac, estado de Guerrero, México. El objetivo fue evaluar los sistemas de producción agrícola que se practican en la zona. El tamaño de muestra fue de 62 entrevistas, aplicada con la técnica de bola de nieve, bajo el método de muestreo por cuotas. Se encontró que en la zona de estudio se cultivan 13 especies vegetales, dentro de las cuales con el maíz, frijol de mata y cebolla se generan tres sistemas de prod...

  11. Accesibilidad geográfica y social en un servicio de salud de especialidad. Acapulco, Guerrero, México, año 2011

    OpenAIRE

    Antonio Reyna Sevilla; Miguel Ernesto González Castañeda; Igor Martín Ramos Herrera

    2013-01-01

    En términos simples, la accesibilidad es la capacidad de interacción entre la oferta y la demanda, por tanto, se configura de acuerdo a características sociales y no únicamente por algunos factores geográficos. El objetivo de este estudio fue describir la accesibilidad geográfica y social en un servicio de salud de especialidad en el estado mexicano de Guerrero. Se desarrolló un estudio transversal con datos provenientes de una cédula de entrevista aplicada a una muestra representati...

  12. The silent earthquake of 2002 in the Guerrero seismic gap, Mexico (Mw=7.6): Inversion of slip on the plate interface and some implications

    OpenAIRE

    Iglesias, A.; Singh, S.K.; A. R. Lowry; M. Santoyo; V. Kostoglodov; K. M. Larson; I. Franco Sánchez

    2004-01-01

    We invert GPS position data to map the slip on the plate interface during an aseismic, slow-slip event, which occurred in 2002 in the Guerrero seismic gap of the Mexican subduction zone, lasted for ~4 months, and was detected by 7 continuous GPS receivers located over an area of ~550x250 km2. Our best model, under physically reasonable constraints, shows that the slow slip occurred on the transition zone at a distance range of 100 to 170 km from the trench. The average slip was about 22.5 cm ...

  13. La poesía de Alfonso Álvarez Guerrero: arte mayor al servicio del Imperio

    Directory of Open Access Journals (Sweden)

    Xavier Tubau

    2012-06-01

    Full Text Available Alfonso Álvarez Guerrero (1502-1576, juriste tolédan qui exerça longtemps sa profession au royaume de Naples, publia en 1520, juste après la diffusion de la nouvelle de l’élection de Charles-Quint comme Roi des Romains, un volume contenant deux œuvres en vers, Las Doscientas del Castillo de la Fama (200 coplas en arte mayor et Las Cincuenta del Laberinto contra Fortuna (50 coplas reales. Dix plus tard, dans le contexte du couronnement impérial de Bologne, un autre volume parut, avec deux nouveaux poèmes: le Palacio de la Fama (154 coplas en arte mayor et l’Historia de las guerras de Italia (354 coplas en arte mayor. Le propos de cet article est de présenter une première analyse du contenu de ces œuvres poétiques. La première partie du travail replace ces œuvres dans le cadre de l’histoire littéraire de l’époque, en soulignant la survivance de la poétique de l’arte mayor – qui prend exemple sur l’œuvre de Juan de Mena – dans les premières décennies du XVIe siècle. La seconde partie tente d’expliquer les implications politiques de certaines idées formulées par l’auteur dans ses poèmes, à la lumière du jeu des diverses factions concurrentes à la cour du jeune empereur, au cours de la décennie de 1520.Alfonso Álvarez Guerrero (1502-1576, jurista toledano que desarrolló buena parte de su trayectoria profesional en el Reino de Nápoles, publicó en 1520, justo después de conocerse la elección de Carlos V como futuro Rey de Romanos, un volumen en el que se incluían dos obras en verso, Las Doscientas del Castillo de la Fama (200 coplas en arte mayor y Las Cincuenta del Laberinto contra Fortuna (50 coplas reales. Diez años más tarde, en el contexto de la coronación imperial en Bolonia, aparecía otro volumen con dos poemas más: el Palacio de la Fama (154 coplas en arte mayor y la Historia de las guerras de Italia (354 coplas en arte mayor. El propósito de este artículo es presentar una primera

  14. Isotopic Studies of the Guerrero Composite Terrane, West-Central Mexico: Implications for Provenance of Crustal Rocks and Ore Metals

    Science.gov (United States)

    Potra, A.; Macfarlane, A. W.; Salters, V. J.; Sachi-Kocher, A.

    2010-12-01

    New Pb, Sr, and Nd isotope analyses of various crustal units and ores from the Guerrero terrane are presented in order to gain insight into their provenance. Mesozoic basement rocks from the Arteaga Complex and Tejupilco metamorphic suite contain radiogenic Pb relative to bulk earth models (206Pb/204Pb between 18.701 and 19.256, 207Pb/204Pb between 15.623 and 15.693, and 208Pb/204Pb between 38.694 and 39.216), plotting to the right of the average Pb crust evolution curve of Stacey and Kramers (1975). The isotopic compositions of Pb in these rocks are substantially more radiogenic than published data on high-grade metamorphic rocks from the Grenvillian-age Oaxaca terrane, but are similar to Paleozoic basement rocks of the Mixteca terrane. Sr and Nd isotope data suggest that the basement rocks of the Guerrero terrane partly originated from ocean-floor rocks which were overlain by sediments derived from a cratonic terrane, possibly represented by the metamorphic complexes of the Oaxaca or Mixteca terranes. Lead isotope ratios of Cretaceous sedimentary rocks of the Zihuatanejo and Huetamo Sequences define two different clusters, with the Zihuatanejo Sequence units shifted to more radiogenic values (206Pb/204 between 18.763 and 19.437, 207Pb/204Pb between 15.580 and 15.643, and 208Pb/204Pb between 38.510 and 38.892). Samples from the Huetamo Sequence are less radiogenic than the metamorphic basement, with Pb isotope ratios between 18.630 and 18.998 for 206Pb/204, 15.563 and 15.641 for 207Pb/204Pb, and 38.369 and 38.610 for 208Pb/204Pb. They plot close to the radiogenic end of the MORB field, suggesting a possible mixing line between the basement rocks and the MORB component. Lead isotope ratios of Tertiary intrusive rocks from La Verde, El Malacate, and La Esmeralda resemble the orogene reservoir in the plumbotectonics model of Zartman and Doe (1981). Plutonic rocks from La Verde show the most radiogenic Pb compositions, suggesting a significant influence of old

  15. Nonvolcanic tremor locations and mechanisms in Guerrero, Mexico, from energy-based and particle motion polarization analysis

    Science.gov (United States)

    Cruz-Atienza, Víctor M.; Husker, Allen; Legrand, Denis; Caballero, Emmanuel; Kostoglodov, Vladimir

    2015-01-01

    We introduce the Tremor Energy and Polarization (TREP) method, which jointly determines the source location and focal mechanism of sustained nonvolcanic tremor (NVT) signals. The method minimizes a compound cost function by means of a grid search over a three-dimensional hypocentral lattice. Inverted metrics are derived from three NVT observables: (1) the energy spatial distribution, (2) the energy spatial derivatives, and (3) the azimuthal direction of the particle motion polarization ellipsoid. To assess the tremor sources, TREP assumes double-couple point dislocations with frequency-dependent quality factors (Q) in a layered medium. Performance and resolution of the method is thoroughly assessed via synthetic inversion tests with random noise, where the "observed" data correspond to an NVT-like finite difference (FD) model we introduce. The FD tremor source is composed of hundreds of quasi-dynamic penny-shaped cracks governed by a time-weakening friction law. In agreement with previous works, epicentral locations of 26 NVTs in Guerrero are separated in two main groups, one between 200 and 230 km from the trench, and another at about 170 km. However, unlike earlier investigations, most NVT hypocenters concentrate at 43 km depth near the plate interface and have subparallel rake angles to the Cocos plate convergence direction. These locations have uncertainties of ~5 km in the three components and are consistent with independent results for low-frequency earthquakes in the region, supporting their common origin related to slip transients in the plate interface. Our results also suggest the occurrence of NVT sources within the slab, ~5 km below the interface.

  16. Biosignatures in modern sulfates: texture, composition and depositional environments of gypsum deposits at Guerrero Negro, Baja, Mexico

    Science.gov (United States)

    Vogel, M. B.; Des Marais, D. J.; Jahnke, L. L.; Turk, K.; Kubo, M.

    2007-12-01

    Gypsum (CaSO4·H2O) is an important phase in biogeochemistry and sedimentology as a mineral sink for sulfur, a paleoclimatic indicator, and an endolithic niche for phototrophic and chemotrophic bacteria. Sulfate deposits are also important targets of exploration for evidence of habitable environments and life on Mars. Gypsum deposits from a range of sedimentary environments at the Guerrero Negro crystallizer ponds and sabkha settings were investigated for microscale structure and composition to differentiate fabrics formed under microbial influence from those formed under abiogenic conditions. Sub-sedimentary gypsum forms in sabkha environments as mm to cm scale selenite discs (termed bird beak gypsum; Warren, 2006) and selenite disc aggregates. Selenite discs and other sub-sedimentary gypsum are characterized by a sinuous axial microtexture and poikilitically enclosed detrital particles. Sub-aqueous gypsum forms as cements, granules (termed gypsooids), and massive botryoidal crusts that line the sediment water interface and margins of managed crystallizer ponds and natural anchialine pools. Sub-aqueous gypsum exhibits a wide range of textures and mineral/biofilm associations that include amorphous to euhedral, tabular, needle and lensoidal morphologies. Elemental sulfur forms rinds on prismatic, growth aligned gypsum twins and reticulate magnesian carbonate is interspersed with both twinned crystals and rosette aggregates in stratified sub-aqueous environments. Intracrystalline biofilms and cell material was observed in association with nearly all sub-aqueous morphologies but only scarce evidence has been found for intercrystalline microbial communities. Columnar microbial communities living in anchialine pools were found to host precipitation of mm scale gypsum granules in their EPS matrix. Fine scale gypsum textures are unlikely to persist through diagenetic alteration, but understanding their primary associations with sulfur and carbonates is necessary for

  17. Characteristics and genesis of hydrothermal dolomites of Qixia and Maokou Formations in northern Sichuan Basin%四川盆地北部栖霞组-茅口组热液白云岩特征与成因

    Institute of Scientific and Technical Information of China (English)

    舒晓辉; 张军涛; 李国蓉; 龙胜祥; 吴世祥; 李宏涛

    2012-01-01

    Taking outcrop dolomites in Cuangyuan Xiagou coal mine in northern Sichuan Basin as an example, this paper studies the characteristics and genesis of hydrothermal dolomite reservoir. From the bottom to the top of the outcrop cross section, the dolomitization gradually enhances;the color of rocks changes from dark to light; the lithologies change from bioclastic limestones to patchy dolostones, then to medium-and coarse-grained dolomites, and end up with the Maokou Formation marlstones. The medium-to coarse-grained dolomites occur at the top of the Qixia Formation and the bottom of the Maokou Formation, and are composed of mediura-to coarsegrained subhedral or euhedral dolomites and some saddle-like dolomites. Dissolved caverns and pores are well-developed and filled with asphaltares. The δ13C value (PDB) and δ18O value (PDB) of micritic limestones are 3.23%and -5. 03 %o, respectively. The δ13C value (PDB) and δ18O value (PDB) of the dolomites are 3. 29 ~ 4. 14%and -6. 07~-6. 75%o respectively. Fluids may be sourced from magmatic hydrothermal fluid,or meteoric water experiencing deep circulation. The deep hydrothermal fluids migrated up along open faults and slowed down or even stopped when arriving at the Qixia and Maokou Formations due to the sealing of marl and politic dolostones in the Wu Jiaping Formation. The stagnant thermal fluids caused dolomitization dissolution of the surrounding rocks. Therefore, it is possible that hydrothermal dolomite reservoirs occur at the top of Qixia Formation and the bottom of Maokou Formation.%以四川盆地北部广元峡沟煤矿剖面白云岩为研究对象,剖面由下部地层向上,白云岩化程度逐渐增强,颜色由深到浅,岩性由生屑灰岩逐渐过渡到斑状白云岩,然后再到中-粗晶白云岩,上部覆盖茅口组泥灰(云)岩.中-粗晶白云岩发育于栖霞组顶部和茅口组底部,由中晶到粗晶的半自形-自形白云石组成,其中可见鞍状白云石.岩石中溶蚀孔洞发

  18. Tectonostratigraphy and depositional history of the Neoproterozoic volcano-sedimentary sequences in Kid area, southeastern Sinai, Egypt: Implications for intra-arc to foreland basin in the northern Arabian-Nubian Shield

    Science.gov (United States)

    Khalaf, E. A.; Obeid, M. A.

    2013-09-01

    This paper presents a stratigraphic and sedimentary study of Neoproterozoic successions of the South Sinai, at the northernmost segment of the Arabian-Nubian Shield (ANS), including the Kid complex. This complex is composed predominantly of thick volcano-sedimentary successions representing different depositional and tectonic environments, followed by four deformational phases including folding and brittle faults (D1-D4). The whole Kid area is divisible from north to south into the lower, middle, and upper rock sequences. The higher metamorphic grade and extensive deformational styles of the lower sequence distinguishes them from the middle and upper sequences. Principal lithofacies in the lower sequence include thrust-imbricated tectonic slice of metasediments and metavolcanics, whereas the middle and upper sequences are made up of clastic sediments, intermediate-felsic lavas, volcaniclastics, and dike swarms. Two distinct Paleo- depositional environments are observed: deep-marine and alluvial fan regime. The former occurred mainly during the lower sequence, whereas the latter developed during the other two sequences. These alternations of depositional conditions in the volcano-sedimentary deposits suggest that the Kid area may have formed under a transitional climate regime fluctuating gradually from warm and dry to warm and humid conditions. Geochemical and petrographical data, in conjunction with field relationships, suggest that the investigated volcano-sedimentary rocks were built from detritus derived from a wide range of sources, ranging from Paleoproterozoic to Neoproterozoic continental crust. Deposition within the ancient Kid basin reflects a complete basin cycle from rifting and passive margin development, to intra-arc and foreland basin development and, finally, basin closure. The early phase of basin evolution is similar to various basins in the Taupo volcanics, whereas the later phases are similar to the Cordilleran-type foreland basin. The

  19. The geologic history of Margaritifer basin, Mars

    Science.gov (United States)

    Salvatore, M. R.; Kraft, M. D.; Edwards, Christopher; Christensen, P.R.

    2016-01-01

    In this study, we investigate the fluvial, sedimentary, and volcanic history of Margaritifer basin and the Uzboi-Ladon-Morava (ULM) outflow channel system. This network of valleys and basins spans more than 8000 km in length, linking the fluvially dissected southern highlands and Argyre Basin with the northern lowlands via Ares Vallis. Compositionally, thermophysically, and morphologically distinct geologic units are identified and are used to place critical relative stratigraphic constraints on the timing of geologic processes in Margaritifer basin. Our analyses show that fluvial activity was separated in time by significant episodes of geologic activity, including the widespread volcanic resurfacing of Margaritifer basin and the formation of chaos terrain. The most recent fluvial activity within Margaritifer basin appears to terminate at a region of chaos terrain, suggesting possible communication between surface and subsurface water reservoirs. We conclude with a discussion of the implications of these observations on our current knowledge of Martian hydrologic evolution in this important region.

  20. The geologic history of Margaritifer basin, Mars

    Science.gov (United States)

    Salvatore, M. R.; Kraft, M. D.; Edwards, C. S.; Christensen, P. R.

    2016-03-01

    In this study, we investigate the fluvial, sedimentary, and volcanic history of Margaritifer basin and the Uzboi-Ladon-Morava outflow channel system. This network of valleys and basins spans more than 8000 km in length, linking the fluvially dissected southern highlands and Argyre basin with the northern lowlands via Ares Vallis. Compositionally, thermophysically, and morphologically distinct geologic units are identified and are used to place critical relative stratigraphic constraints on the timing of geologic processes in Margaritifer basin. Our analyses show that fluvial activity was separated in time by significant episodes of geologic activity, including the widespread volcanic resurfacing of Margaritifer basin and the formation of chaos terrain. The most recent fluvial activity within Margaritifer basin appears to terminate at a region of chaos terrain, suggesting possible communication between surface and subsurface water reservoirs. We conclude with a discussion of the implications of these observations on our current knowledge of Martian hydrologic evolution in this important region.

  1. Comunidad de parásitos metazoarios de la charra Cichlasoma trimaculatum en la laguna de Tres Palos, Guerrero, México Metazoan parasite community in the three-spot cichlid Cichlasoma trimaculatum from Tres Palos Lagoon, Guerrero, Mexico

    Directory of Open Access Journals (Sweden)

    Juan Violante-González

    2008-12-01

    Full Text Available Entre abril de 2000 y noviembre de 2002 se examinó la composición de la comunidad de parásitos metazoarios de la charra, Cichlasoma trimaculatum a partir de muestras temporales. Fueron recuperadas 12 especies de parásitos (40 969 individuos de 231 hospederos examinados; 10 helmintos: Ascocotyle (Phagicola longa, Austrodiplostomum compactum, Cladocystis trifolium, Clinostomum complanatum, Crassicutis cichlasomae, Posthodiplostomum minimum, Pseudoacanthostomum panamense, Neoechinorhynchus golvani, Southwellina hispida y Contracaecum sp., y 2 crustáceos: Argulus sp. y Ergasilus sp. La comunidad se caracterizó por un número mayor de parásitos generalistas y pocos especialistas de cíclidos, además por ser pobre en especies. De las 5 especies comunes dentro de la comunidad, 4 presentaron variación temporal en su dinámica de infección a lo largo del tiempo, la cual fue asociada con cambios ambientales generados durante las temporadas de secas y lluvias. La variación en la dinámica de infección de las especies comunes fue capaz de generar cambios en la estructura, tanto en el nivel de componente como en el de infracomunidad; sin embargo, no se observó un patrón claro, lo que indica que la comunidad puede ser poco predecible, como se sugiere para otras comunidades de parásitos de peces dulceacuícolas.We analyzed metazoan parasite community composition in the three-spot cichlid Cichlasoma trimaculatum using seasonal samples taken between April 2000 and November 2002 from the Tres Palos Lagoon, Guerrero, Mexico. A total of 231 hosts were examined. Of the 12 parasite species recovered (40,969 individuals, 10 were helminths: Ascocotyle (Phagicola longa, Austrodiplostomum compactum, Cladocystis trifolium, Clinostomum complanatum, Crassicutis cichlasomae, Posthodiplostomum minimum, Pseudoacanthostomum panamense, Neoechinorhynchus golvani, Southwellina hispida, and Contracaecum sp. The remaining 2 were the crustaceans Argulus sp. and

  2. Interaction of Extreme Halophilic Archaea With the Evaporites of the Solar Salterns Guerrero Negro Baja California, Mexico

    Science.gov (United States)

    Tamez, P.; Lopez-Cortés, A.

    2008-12-01

    Hypersaline environments have been significant reservoirs for the long-term evolution of specifically adapted microorganisms. Characterized to have higher salt concentrations (up to 35 g/L), they are worldwide distributed and have a commercial significance. Exportadora de Sal, Guerrero Negro, Mexico has a multipond salterns system designed to harvest common salt (NaCl) from sea water. To achieve this purpose, sea water is pumped through a set of shallow ponds where water evaporates and salts concentrate. Sequential precipitation of CaCO3, CaSO4 2H2O and NaCl occurs in a mineral formations call it evaporites. In the interior of those gypsum-encrusted and halite-encrusted minerals, communities of extremely salt-loving archaea prosper. Previous studies have showed the influence of Haloarchaeal cells in the formation of larger fluid inclusions than crystals formed in sterile salt solutions. S-layer envelopes and cells of Haloarcula strain SP8807 contributed to the nucleation of new crystals of NaCl. Given the significance of the scope in phylogenetic archaeal diversity research, this study had a polyphasic approach. SEM micrographs from a 21- 31% (w/v) gradient salt multipond system evaporites, gave an insight profile of the extreme halophilic archaeal communities thriving in the surface of the gypsum and halite evaporites. Halite crystals were form after 21 days of incubation in solid medium with archaeal cells. Both culture and non-culture dependent methods, Nested-PCR-DGGE analysis and sequencing of 16S rDNA amplified fragment genes from environmental samples and isolated strains were used for this purpose. We isolate three strains from Pond 9 (21.07% total salt concentration) and one strain from Cristallizer 20 (25.15% total salt concentration). 16S rDNA signaling gave 99% of similarity with Halogeometricum borinquense, sequence AF002984, two other strains were 99% of similarity with Halobacterium salinarum, sequence AJ496185 these strains shown different colony

  3. AGRICULTURAL PRACTICES, MORPHOLOGIC, PROTEINIC AND CULINARY DESCRIPTION OF THE GRAIN OF BEAN CULTIVARS SOWED IN THE REGION OF TLATZALA, GUERRERO

    Directory of Open Access Journals (Sweden)

    Fausto Solano Cervantes

    2009-08-01

    Full Text Available The research had for object describe the productive process of the of bean culture in the community of Tlatzala, Guerrero and the species diversity by means of the morphologic characteristics of the grain, protein content and the culinary quality. 30 questionnaires were applied to bean producers and 20 varieties of bean were collected from which the morphologic characters of the grain, protein content and the culinary characters were obtained. The production cycle of bean initiates in May and finishes in October. The technology used is traditional, characterized by the use of the yoke in the labors of the culture that demands workforce to realize the activities of manual form. The biological cycle of the varieties begins in June, the variation at time is determinated for the cultivated genotype. The determinate or indeterminate bush beans are predominant (65 %. The sowing systems are intercalated (50 % and associated with maize (30 % and monoculture (20 %. The varieties Rojito and Blanco have special uses, the first one has the attribute of being consumed as green-bean all the year around and the second one is used to prepare the dish called Chile-ajo. The Black beans were the most frequent (45 % followed by the Red beans (35 % and the least frequent were the Striped one (5 % and Muddy-like (5 %. The kidney shape of grain was the most abundant (85 % and the oval one was the least frequent (5 %. The grain weight changed from 14.4 up to 38.5 g. The sizes of grains founded were medium (50 % and small (50 %. The protein content registered was: White beans 24.68 %, Red bean 24.64 %, Black beans 23.5 % and Striped beans of guide 22.27 %. The Rojito Enano had the major protein content (27.6 %. The cooking times were: Red beans 73 minutes, Striped of guide bean 65.5, Blacks bean 64.6 and Whites bean 59. The Black bean Enano-1 used less time (54 minutes. The Striped of guide bean registered the major amount of solid (0.32 %, followed by the Black beans

  4. Índice de sustentabilidad para el sistema bovino de doble propósito, en Guerrero, México

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    Hernández Valenzuela, Daniel; ;

    2006-09-01

    Full Text Available La agricultura sustentable, es un proceso, en el cual las demandas deproductos, son satisfechas por unidades de producción, económicamenteeficientes, ambientalmente amigables y socialmente aceptables. El presente estudio se realizó en la Costa Chica del estado de Guerrero, México, en el Océano Pacífico, ubicado entre los 16º 18´ y 18º 48´ de latitud norte y los 98º 03´ y 102º 12´ de longitud oeste, cuyoobjetivo fue determinar el índice de sustentabilidad de la ganadería de doblepropósito (carne y leche. Para ello se realizó una encuesta directa conproductores, mediante muestreo simplealeatorio, tendiendo como marco demuestreo las listas de socios de lasAsociaciones Ganaderas Locales. Asímismo, se realizaron visitas periódicas alas unidades de producción, para obtenerinformación de rendimiento de leche ycarne, instalaciones, manejo einventarios. Con los datos obtenidos, secalcularon los estadísticos descriptivos yse realizó el análisis de componentesprincipales para reducir la dimensión delconjunto de variables, minimizando lapérdida de información. Posteriormentese realizó un análisis de conglomeradospara identificar grupos de productorescon características comunes. Con esosgrupos, se evalúo la sustentabilidad delsistema de producción, de acuerdo a lametodología propuesta por el IICA. Losresultados permiten describir unsistema, basado en animales conproducciones por lactancia de 781 ± 591kg, ordeñadas durante 148 días ± 88,cuya práctica la realiza el 36% de losproductores, en días alternos o en formaesporádica. Los ingresos promedio de lasunidades productivas, fueron de$67,364.00 anuales, con unarentabilidad sobre costos variables de486%. La magnitud de los índices desustentabilidad, para los productores fuede 0.427, para la dimensión social, de0.493; para la dimensión económica,0.482 y para la dimensión ambiental de0.358, lo que evidenció una ganaderíaque se aleja paulatinamente de

  5. Pteridophyta collected in Northern Nigeria and Northern Cameroon

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    Jan kornaś

    2014-02-01

    Full Text Available 25 species of Pteridophyta were collected in Northern Nigeria (mainly the Lake Chad Basin and the Mandara Mts. and in the neighbouring parts of Cameroon. 11 of them have not been recorded previously from this area: Isoetes schweinfurthii A. Br. in Bak., Selaginella tenerrima A. Br. ex Kuhn, Ophioglossum gomenzianum Welw. ex A. Br., Marsilea coromandeliana Willd., M. distorta A. Br., M. nubica A. Br., M. subterranea Lepr. ex A. Br., Azolla africana Desv., Ceratopteris richardii Brogn., Adiantum capillus-veneris Linn., and Actiniopleris semiflabellata Pic. Ser.

  6. 松辽盆地北部T2反射层断裂密集带成因机制%Genetic Mechanism of T2 Reflector Fault Dense Zones in Northern Songliao Basin

    Institute of Scientific and Technical Information of China (English)

    孙永河; 白鹿; 付晓飞

    2013-01-01

    松辽盆地北部T2反射层断裂与中浅层油气的运聚成藏关系紧密,揭示T2反射层断裂密集带的成因机制对指导油气勘探至关重要.基于松辽盆地北部区域地震解释,从分析断裂发育特征着手,以断裂形成演化过程为主线,系统剖析了盆地演化不同阶段断裂的变形机制,揭示了T2反射层断裂密集带的形成机制及其对油气运聚成藏的指示作用.研究表明,T2反射层断裂密集带是在断陷演化基础上,在断陷期断裂先存构造、泉一二段塑性泥岩盖层水平拆离作用和近EW向拉张应力场的控制下形成的,全区以近SN向拉张机制伸展型密集带为主,NE向、NW向和近EW向斜拉机制调节型密集带和走滑调节型密集带零星分布.盆地反转期受断陷半地堑、基底深大断裂和左旋压扭变形场控制形成反转构造带的同时,反转构造带内的断裂密集带被逆时针旋转改造而定型,呈NW-NNW向展布为主.反转构造带内T2反射层NW-NNW向断裂密集带边部断裂和未反转区带内T2反射层近SN向断裂密集带边部断裂长期活动,与油气大量生排烃时期匹配,是中浅层油气运聚成藏的油源断层.%The relationship between T2 reflector fault and hydrocarbon accumulation reservoir of middle-shallow layer is close,which proves genetic mechanism of T2 reflector fault dense zones is important for hydrocarbon exploration.Based on the northern Songliao basin regional seismic interpretation,the analysis of the development characteristics and the formation and evolution of fault,we systematically analyze fault deformation mechanism at different stages,which reveal formation mechanism of T2 reflector fault dense zones and indication of hydrocarbon exploration.This study shows that T2 reflector fault dense zones have been formed through the following three preriods,namely,the initial faulted period,pre-structure in faulted period,and level detachment of plastic rnudstone cap rock

  7. Exploración y caracterización morfológica de poblaciones de la jamaica (Hibiscus sabdariffa L.) del estado de Guerrero, México Morphological exploration and characterization of roselle (Hibiscus sabdariffa L.) populations from state of Guerrero, Mexico

    OpenAIRE

    Noé Alarcón-Cruz; Rafael Ariza Flores; Aristeo Barrios Ayala; David H. Noriega Cantú; Juan Porfirio Legaria Solano

    2012-01-01

    El presente estudio se realizó en las instalaciones de la Universidad Autónoma Chapingo durante el periodo de 2007 a 2009 y tuvo como objetivo caracterizar morfológicamente a 47 colectas de jamaica (Hibiscus sabdariffa L.) que representaron a poblaciones del estado de Guerrero. En la caracterización morfológica se evaluaron 50 variables, mismas que se separaron en 40 cuantitativas y 10 cualitativas. De las cuantitativas se seleccionaron 25 variables y de las cualitativas cinco con alta signif...

  8. Prevalence of Resistant Strains of Rhipicephalus microplus to Acaricides in Cattle Ranch in the Tropical Region of Tecpan of Galeana, Guerrero, Mexico

    Directory of Open Access Journals (Sweden)

    J. Olivares-Pérez*, S. Rojas-Hernández, M.T. Valencia-Almazan, I. Gutiérrez-Segura and E.J. Míreles-Martínez

    2011-10-01

    Full Text Available Tick and tick borne diseases cause many problems to the cattle industry worldwide. The prevalence of resistant strains of Rhipicephalus microplus to different acaricides on cattle farms in the tropical region of Tecpan of Galeana, Guerrero, Mexico, and risk factors related to prevalence of resistant strains of R. microplus. Sixty one ranches infested were sampled; in each ranch were collected 30-50 fully-engorged female R. microplus ticks, of 10 cattle randomly selected, and evaluated in their progeny resistance to acaricides, using the larval packet test. The prevalence of resistant strains was total pyrethroids and amitraz. In organophosphorus 31.1, 48.3 and 82.2% of strains were resistant to clorpyriphos, coumaphos and diazinon, respectively. Risk factors favored (P<0.05 the development of resistant strains of acaricides. We concluded that the resistance of R. microplus to acaricides used to control a problem, and risk factors (livestock management have accelerated the development of resistance.

  9. ANÁLISIS DE LA EFECTIVIDAD DE LA DIAGNOSIS DEL DENGUE EN EL ESTADO DE GUERRERO, MÈXICO 2007: HECHOS ESTADÌSTICOS Y CONSENSO

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    Sira Allende *, Carlos Bouza *; Saúl López Silva** y Agustín S. Moreno***

    2008-02-01

    Full Text Available This paper presents a study of the clinical criteria on the persons consulting the physicians considering, that they were affected by dengue, in the state of Guerrero, México, during 2006. The classification made by the clinic was evaluated with respect to the golden rule represented by the laboratory results. All the consulted persons with the symptoms were studied. The consensus between physicians and laboratory was evaluated by studying the collected data and computing the most popular indices of consensus. It was established that a low consensus level was present in the prediction of classical dengue while the levels for the hemorrhagic were more adequate. This study was developed in each state jurisdiction. This the first occasion in which this study is developed. It and the analysis of the data gave an overall idea of the behavior of the epidemic.

  10. La producción de cabras en la cañada de Huamuxtitlán, estado de Guerrero.

    OpenAIRE

    Melchor García, Juan

    2014-01-01

    Se caracterizó el sistema de producción y el tipo de cabras en la Cañada de Huamuxtitlán en la Montaña de Guerrero. Se realizaron 70 entrevistas con un cuestionario en el que se registró información de la familia, tierra, cultivos, prácticas de manejo y la comercialización. Para la caracterización de las cabras se midieron 263 cabras adultas. Se registró el sexo, raza, edad, caracteres externos y 18 variables zoométricas. La información del sistema de producción y de las cabras se analizó med...

  11. Análisis espacial de los aspectos demográficos, agrarios y ambientales de tres municipios de La Montaña de Guerrero

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    Karina Pérez Reyna

    1998-01-01

    Full Text Available Can base en el uso de un sistema de información geográfica (ILWIS, se examinan los aspectos ecológicos. caracteristicas demográficas, limites agrarios, sistemas de producción y grados de deterioro ambiental en las comunidades indígenas de los municipios de Tiapa, Xaipatláhuac y Copanatoyac de la Montaña de Guerrero. Se llega. al final del estudio, a aseverar que los patrones de vida y el tipo de tecnología empleada en el maneja de recursos naturales, más que la densidad de población municipal son factores que tienen que ver con la degradación del ambiente

  12. The age and composition of the pre-Cenozoic basement of the Jalisco Block: implications for and relation to the Guerrero composite terrane

    Science.gov (United States)

    Valencia, Victor A.; Righter, Kevin; Rosas-Elguera, Jose; López-Martínez, Margarita; Grove, Marty

    2013-09-01

    The Jalisco Block is thought to be part of the Guerrero terrane, but the nature and age of the underlying crystalline basement are largely unknown. We have collected a suite of schists, granitoids, and weakly metamorphosed marine sediments from various parts of the Jalisco Block including Atenguillo and Ameca, Mascota and San Sebastián, Cuale, Puerto Vallarta, Punta Mita, Yelapa, and Tomatlán. The schists range in age from 135 to 161 Ma, with many exhibiting Proterozoic and Phanerozoic zircon ages. The granitoids range in age from 65 to 90 Ma, and are calc-alkaline compositionally—similar to granitoids from the Puerto Vallarta and Los Cabos batholiths. The Jalisco granitoids also experienced similar uplift rates to granitoids from the regions to the north and south of the Jalisco Block. The marine sediments yield a maximum depositional age of 131 Ma, and also contain a significant zircon population with ages extending back to the Archean. Granitoids from this study define two age groups, even after the effects of thermal resetting and different closure temperatures are considered. The 66.8-Ma silicic ash flow tuff near Union de Tula significantly expands the extent of this Cretaceous-Paleocene age ash flow tuff unit within the Jalisco Block, and we propose calling the unit "Carmichael silicic ash flow tuff volcanic succession" in honor of Ian Carmichael. The ages of the basement schists in the Jalisco Block fully overlap with the ages of terranes of continental Mexico, and other parts of the Guerrero terrane in the south, confirming the autochthonous origin of the Jalisco Block rather than exotic arc or allochthonous origin. Geologic data, in combination with geochronologic and oxygen isotopic data, suggest the evolution of SW Mexico with an early 200-1,200-Ma passive margin, followed by steep subduction in a continental arc setting at 160-165 Ma, then shallower subduction by 135 Ma, and finally, emplacement of granitoids at 65-90 Ma.

  13. The discovery of Late Bathonian-Early Callovian ammonites in the middle of northern Qiangtang basin, Tibetan Plateau%青藏高原北羌塘盆地中部发现晚巴通期—早卡洛夫期菊石

    Institute of Scientific and Technical Information of China (English)

    曾胜强; 王剑; 陈明; 付修根; 吴滔; 熊兴国

    2012-01-01

    最近在北羌塘盆地中部半岛湖地区索瓦组下段中发现了丰富的中体罗世晚巴通期—早卡洛夫期菊石.这些菊石保存好,特征明显,可以与西特提斯地中海区菊石带进行精细对比.根据区域菊石化石群的对比,含菊石的地层可能不是索瓦组下段,而是夏里组.早卡洛夫期大头菊石的出现与同期全球海平面的上升同步,而地方性的含大头菊石的层序通常也指示了区域性的海侵.羌塘盆地早卡洛夫期大头菊石生物群的发现,证明羌塘盆地在早卡洛夫期还存在区域性的海侵,北羌塘盆地中部的半岛湖地区处于相对较深的广海碳酸盐台地环境,而不是前人所认为的羌塘盆地在卡洛夫期即发生大规模的海退,发生海退的时间应该在早卡洛夫期之后.晚巴通期-早卡洛夫期菊石生物群的发现对于重新认识羌塘盆地沉积构造演化历史具有重要意义.%Recently, a number of ammonites were discovered in the Bandao Lake area of northern Qiangtang basin, ranging in age from the Late Bathonian to Early Callovian (Middle Jurassic). The ammonite assemblages sampled in the Changhong River area are of good preservation and have obvious features, thus providing a solid basis for comparison widi the Western Tethys ammonoid zones. According to the comparison with regional ammonoid assemblages, the fossiliferous strata are probably Xiali Formation instead of the lower part of the Suowa Formation. The generation of Macrocephalites in the Early Callovian time was closely connected with the global rising sea level, and the endemic Macrocephalites sequences often indicate a regional transgression event. The existence of Early Callovian Macrocephalites in the middle Qiangtang basin implies that a regional transgression took place in the Qiangtang basin during the Early Callivian period, and the Bandao Lake area in the middle of the northern Qiangtang basin was in a relatively deep carbonate platform

  14. Determination of the Relationship between Hydrologic Processes and Basin Morphometry - The Lamos Basin (Mersin, Turkey)

    Science.gov (United States)

    Yıldırım, Ümit; Güler, Cüneyt

    2016-04-01

    This study has been carried out to determine the relationship between hydrologic processes and basin morphometry in the Lamos Basin, which is located at the northern part of the Mersin (SE Turkey). The morphometric parameters of the basin was derived from the 1:25K scale topographic map sheets that were digitized using ArcGIS 9.3.1 geographic information system (GIS) software. Morphometric parameters considered in this study include basin area, basin length, basin perimeter length, stream order, stream number, stream length, mean stream length, basin relief, drainage density, stream frequency, drainage texture, bifurcation ratio, form factor, elongation ratio, overland flow length, relief ratio, and hypsometric integral. The results have shown that there are 1252 individual stream reaches with a total length of 1414.1 km in the Lamos basin, which covers an area of 1358 km2 and has a length of 103 km in the N-S direction. Furthermore, the basin has a medium drainage density of 1.04 1/km with a stream frequency and drainage texture values of 0.92 and 4.33, respectively. The basin can be classified as elongated because of the low values of elongation ratio (0.48) and form factor (0.12). The hypsometric integral of the basin (0.58) indicates that it is in the youth period and thus reasonably sensitive to erosion. The values of drainage texture, drainage density, and stream frequency indicate that the Lamos basin is moderately well drained, therefore overland flow in the basin is not expected to be so quick. Thus, in case of occurrence of sudden peak flows, sensitivity to the land sliding and erosion may increase further. As a result, it is suggested that human activities in the basin should be limited in areas in fairly close proximity to the present day stream network to prevent or reduce the risk to life and property.

  15. Geodynamics of the Sivas Basin (Turkey): from a forearc basin to a retroarc foreland basin

    Science.gov (United States)

    Legeay, Etienne; Ringenbach, Jean-Claude; Kergaravat, Charlie; Callot, Jean-Paul; Mohn, Geoffroy; Kavak, Kaan

    2016-04-01

    Anatolia records the consumption of several oceanic basins, from the Northern Neotethys domain, by north-dipping subduction until the end of Mesozoic. The associated obduction event occurred during Campanian, from North to South and from Greece to Oman, leading to the emplacement of ophiolite thrust sheets and associated ophiolitic mélange. In particular, the Sivas Basin in Eastern Anatolia is located at the boundary between the Kırsehir block to the East, Pontide arc to the North and Tauride Platform to the South, sutured by ophiolitic belts. The Sivas Basin formed a Tertiary fold-and-thrust belt, which exhibits mainly north verging thrust in Paleogene deposits, and South verging thrust in oligo-miocene sequence. To understand the northern verging thrust above south verging obduction, it is necessary to zoom out of the basin, and include a set of processes that affect the eastern Anatolia. This study aims to characterize the structural and sedimentary evolution of the Sivas Basin, based on a fieldwork approach, coupled to the interpretation of subsurface data, thermochronology and biostratigraphy. The Sivas Basin was initiated in a forearc setting relatively to the subduction of the Inner-Tauride Ocean while the associated ophiolites are obducted onto the northern passive margin of the Tauride margin. Early Maastrichtian to Paleocene deposits are represented by carbonate platforms located on ophiolitic highs, passing to turbidites and olistostomes toward the North. The early Eocene sediments, mainly composed of ophiolitic clasts, are deposited on a regional unconformity marked along the southern margin of the basin by incisions in response to the emergence of north-verging thrust. The middle Eocene sediments, intensively folded by northward thrusting, are mostly represented by flysch type deposits (olistostromes, mass-flows and turbidites). The onset of the compression is related to the initiation of the Taurus shortening in a retroarc situation, in response to

  16. Fiabilité sismique des bâtiments en bétons armés érigés sur un sol dur avec épicentre proche (cas de Guerrero, Mexique)

    OpenAIRE

    Pérez Gómez, David

    2009-01-01

    With real information provided by Mexican Institution, we begin this research. The objective is to measure the indexes of reliability of reinforced concrete buildings subjected to real seismic forces with near epicenter, erected on hard soil. There is a need to assess the uncertainty affecting the buildings in the State of Guerrero, since geophysical researches estimate a GAP of area of 220x90 2 km , which will generate an earthquake of Magnitude Mw=8.4. We expect that the predominant period ...

  17. Étude expérimentale et numérique des murs en maçonnerie confinée chargés dans leur plane : cas : état de Guerrero (Mexique)

    OpenAIRE

    Sánchez Tizapa, Sulpicio

    2009-01-01

    This research work proposes methods to rises the resistance and to evaluate the behavior of confined masonry walls built from clay solid bricks. These elements are widely used in Guerrero State (México) to build masonry structures, which should resist high lateral loads because of the serious seismic hazard. Therefore, a large experimental program to evaluate the mechanical properties of bricks and masonry currently required in the design process and masonry analysis was developed. To rises t...

  18. The structure of Nansen and Amundsen Basin

    Science.gov (United States)

    Micksch, U.; Jokat, W.

    2003-04-01

    During the AMORE expedition in August/September 2001, a US-German joint project, the Gakkel Ridge and the adjoining basins were investigated. In this contribution we report on the results of the seismic investigations in the Nansen Basin as well as in the Amundsen Basin. We obtained two almost parallel profiles through the Nansen Basin from the northeastern continental margin of Svalbard (29°E and 32°E) to the Gakkel Ridge at 17°E and 21°E. To investigate the Amundsen Basin, we left Gakkel Ridge at about 70°E towards Lomonossov Ridge for another transect. In total 1360 km of seismic reflection data with very good data quality were recorded. Parallel to the seismic reflection transects up to 30 sonobuoys were deployed. The data from both basins shows striking differences in the basement topography. While in the Nansen Basin the oceanic crust is more or less continuously shallowing, this is not the case in the Amundsen Basin. This points to some asymmetric spreading history of the Gakkel Ridge in northern and southern directions. Some of the Sonobuoys recorded also weak arrivals from the Moho discontinuity. The analysis of the wide angle and gravity data shows, that there are areas with a significant thinning of the oceanic crust. Results of