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Sample records for williston basin implications

  1. Improved Recovery Demonstration for Williston Basin Carbonates

    Energy Technology Data Exchange (ETDEWEB)

    Larry A. Carrell

    1997-12-31

    The purpose of this project is to demonstrate targeted infill and extension drilling opportunities, better determinations of oil-in-place, methods for improved completion efficiency and the suitability of waterflooding in certain shallow-shelf carbonate reservoirs in the Williston Basin, Montana, North Dakota and South Dakota. Improved reservoir characterization utilizing three-dimensional is being investigated for identification of structural and stratigraphic reservoir compartments. These seismic characterization tools are integrated with geological and engineering studies. Improved completion efficiency is being tested with short-lateral and horizontal drilling technologies. Improved completion efficiency, additional wells at closer spacing and better estimates of oil-in-place will result in additional oil production by primary and enhanced recovery processes.

  2. Thickness of the middle Fort Union hydrogeologic unit in the Williston structural basin

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — These data represent the thickness, in feet, of the middle Fort Union hydrogeologic unit in the Williston structural basin. The data are presented as ASCII text...

  3. Altitude of the top of the lower Fort Union aquifer in the Williston structural basin

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — These data represent the altitude, in feet above North American Vertical Datum of 1988 (NAVD88), of the lower Fort Union aquifer in the Williston structural basin....

  4. Thickness of the lower Fort Union aquifer in the Williston structural basin

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — These data represent the thickness, in feet, of the lower Fort Union aquifer in the Williston structural basin. The data are presented as ASCII text files that can...

  5. Altitude of the top of the upper Fort Union aquifer in the Williston structural basin

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — These data represent the altitude, in feet above North American Vertical Datum of 1988 (NAVD88), of the upper Fort Union aquifer in the Williston structural basin....

  6. Thickness of the upper Fort Union aquifer in the Williston structural basin

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — These data represent the thickness, in feet, of the upper Fort Union aquifer in the Williston structural basin. The data are presented as ASCII text files that can...

  7. Evaluation of injection well risk management potential in the Williston Basin

    Energy Technology Data Exchange (ETDEWEB)

    None

    1989-09-01

    The UIC regulations promulgated by the EPA under the Safe Drinking Water Act (SDWA) provide the EPA, or an EPA approved state agency, with authority to regulate subsurface injection of fluids to protect USDWs. Oil and gas producing industry interests are concerned primarily with Class 2 wells whose uses as defined by UIC regulations are: disposal of fluids brought to the surface and liquids generated in connection with oil and gas production (SWD); injection of fluids for enhanced oil recovery (EOR); and storage of liquid hydrocarbons. The Williston Basin was chosen for the pilot study of the feasibility of using the risk approach in managing Class 2 injection operations for the following reasons: it is one of the nine geologic basins which was classified as having a significant potential for external casing corrosion, which permitted an evaluation of the effectiveness of the injection well corrosion control measures used by industry; there are 731 active, 22 shut in and 203 temporarily abandoned SWD and water injection wells in the basin; and the basin covers three states. The broad objective of the Williston Basin study is to define requirements and to investigate the feasibility of incorporating risk management into administration of the UIC program. The study does not address the reporting aspects of UIC regulatory and compliance activities but the data base does contain essentially all the information required to develop the reports needed to monitor those activities. 16 refs., 10 figs., 11 tabs.

  8. Improved recovery demonstration for Williston basin carbonates. Annual report, June 10, 1994--June 9, 1995

    Energy Technology Data Exchange (ETDEWEB)

    Sippel, M.; Zinke, S.; Magruder, G.; Eby, D.

    1995-09-01

    The purpose of this project is to demonstrate targeted infill and extension drilling opportunities, better determinations of oil-in-place, methods for improved completion efficiency and the suitability of waterflooding in Red River and Ratcliffe shallow-shelf carbonate reservoirs in the Williston Basin, Montana, North Dakota and South Dakota. Improved reservoir characterization utilizing three-dimensional and multi-component seismic are being investigated for identification of structural and stratigraphic reservoir compartments. These seismic characterization tools are integrated with geological and engineering studies. Improved completion efficiency is being tested with extended-reach jetting lance and other ultra-short-radius lateral technologies. Improved completion efficiency, additional wells at closer spacing and better estimates of oil in place will result in additional oil recovery by primary and enhanced recovery processes.

  9. Regional-scale flow of formation waters in the Williston basin

    Energy Technology Data Exchange (ETDEWEB)

    Bachu, S. [Alberta Department of Energy, Edmonton (Canada); Hitchon, B. [Hitchion Geochemical Services Ltd., Alberta (Canada)

    1996-02-01

    The Williston basin is a structurally simple intracratonic sedimentary basin that straddles the United States-Canada border east of the Rocky Mountains and that contains an almost continuous stratigraphic record since the Middle Cambrian. Based on the wealth of data generated by the oil industry, the regional-scale characteristics of the flow of formation waters were analyzed for the Canadian side of the basin, and integrated with previous studies performed on the American side. Several aquifers and aquifer systems identified in the basin were separated by intervening aquitards and aquicludes. The Basal, Devonian, and Mannville (Dakota) aquifers are open systems, being exposed at the land surface in both recharge and discharge areas. Recharge takes place in the west-southwest at relatively high altitude in the Bighorn and Big Snowy mountains and at the Black Hills and Central Montana uplifts, whereas discharge takes place in the east and northeast at outcrop along the Canadian Precambrian shield in Manitoba and the Dakotas. The Mississippian and Pennsylvanian aquifer systems are semi-open, cropping out only in the west-southwest where they recharge, but discharging in the northeast into adjacent aquifers through confining aquitards. On regional and geological scales, the entire system seems to be at steady-state, although locally transient flow is present in places due to water use and hydrocarbon exploitation, and to some erosional rebound in the uppermost confining shales. On the western flank of the basin, the interplay between the northeastward structural downdip direction and the northeastward flow of formation waters creates conditions favorable for hydrodynamic oil entrapment.

  10. Conceptual model of the uppermost principal aquifer systems in the Williston and Powder River structural basins, United States and Canada

    Science.gov (United States)

    Long, Andrew J.; Aurand, Katherine R.; Bednar, Jennifer M.; Davis, Kyle W.; McKaskey, Jonathan D.R.G.; Thamke, Joanna N.

    2014-01-01

    The three uppermost principal aquifer systems of the Northern Great Plains—the glacial, lower Tertiary, and Upper Cretaceous aquifer systems—are described in this report and provide water for irrigation, mining, public and domestic supply, livestock, and industrial uses. These aquifer systems primarily are present in two nationally important fossil-fuelproducing areas: the Williston and Powder River structural basins in the United States and Canada. The glacial aquifer system is contained within glacial deposits that overlie the lower Tertiary and Upper Cretaceous aquifer systems in the northeastern part of the Williston structural basin. Productive sand and gravel aquifers exist within this aquifer system. The Upper Cretaceous aquifer system is contained within bedrock lithostratigraphic units as deep as 2,850 and 8,500 feet below land surface in the Williston and Powder River structural basins, respectively. Petroleum extraction from much deeper formations, such as the Bakken Formation, is rapidly increasing because of recently improved hydraulic fracturing methods that require large volumes of relatively freshwater from shallow aquifers or surface water. Extraction of coalbed natural gas from within the lower Tertiary aquifer system requires removal of large volumes of groundwater to allow degasification. Recognizing the importance of understanding water resources in these energy-rich basins, the U.S. Geological Survey (USGS) Groundwater Resources Program (http://water.usgs.gov/ogw/gwrp/) began a groundwater study of the Williston and Powder River structural basins in 2011 to quantify this groundwater resource, the results of which are described in this report. The overall objective of this study was to characterize, quantify, and provide an improved conceptual understanding of the three uppermost and principal aquifer systems in energy-resource areas of the Northern Great Plains to assist in groundwater-resource management for multiple uses. The study area includes parts of Montana, North Dakota, South Dakota, and Wyoming in the United States and Manitoba and Saskatchewan in Canada. The glacial aquifer system is contained within glacial drift consisting primarily of till, with smaller amounts of glacial outwash sand and gravel deposits. The lower Tertiary and Upper Cretaceous aquifer systems are contained within several formations of the Tertiary and Cretaceous geologic systems, which are hydraulically separated from underlying aquifers by a basal confining unit. The lower Tertiary and Upper Cretaceous aquifer systems each were divided into three hydrogeologic units that correspond to one or more lithostratigraphic units. The period prior to 1960 is defined as the predevelopment period when little groundwater was extracted. From 1960 through 1990, numerous flowing wells were installed near the Yellowstone, Little Missouri and Knife Rivers, resulting in local groundwater declines. Recently developed technologies for the extraction of petroleum resources, which largely have been applied in the study area since about 2005, require millions of gallons of water for construction of each well, with additional water needed for long-term operation; therefore, the potential for an increase in groundwater extraction is high. In this study, groundwater recharge and discharge components were estimated for the period 1981–2005. Groundwater recharge primarily occurs from infiltration of rainfall and snowmelt (precipitation recharge) and infiltration of streams into the ground (stream infiltration). Total estimated recharge to the Williston and Powder River control volumes is 4,560 and 1,500 cubic feet per second, respectively. Estimated precipitation recharge is 26 and 15 percent of total recharge for the Williston and Powder River control volumes, respectively. Estimated stream infiltration is 71 and 80 percent of total recharge for the Williston and Powder River control volumes, respectively. Groundwater discharge primarily is to streams and springs and is estimated to be about 97 and 92 percent of total discharge for the W

  11. Altitude of the top of the middle Fort Union hydrogeologic unit in the Williston structural basin

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — These data represent the altitude, in feet above North American Vertical Datum of 1988 (NAVD88), of the middle Fort Union hydrogeologic unit in the Williston...

  12. Reservoir characterization of the Mississippian Ratcliffe, Richland County, Montana, Williston Basin. Topical report, September 1997

    Energy Technology Data Exchange (ETDEWEB)

    Sippel, M.; Luff, K.D.; Hendricks, M.L.

    1998-07-01

    This topical report is a compilation of characterizations by different disciplines of the Mississippian Ratcliffe in portions of Richland County, MT. Goals of the report are to increase understanding of the reservoir rocks, oil-in-place, heterogeneity and methods for improved recovery. The report covers investigations of geology, petrography, reservoir engineering and seismic. The Ratcliffe is a low permeability oil reservoir which appears to be developed across much of the study area and occurs across much of the Williston Basin. The reservoir has not been a primary drilling target in the study area because average reserves have been insufficient to payout the cost of drilling and completion despite the application of hydraulic fracture stimulation. Oil trapping does not appear to be structurally controlled. For the Ratcliffe to be a viable drilling objective, methods need to be developed for (1) targeting better reservoir development and (2) better completions. A geological model is presented for targeting areas with greater potential for commercial reserves in the Ratcliffe. This model can be best utilized with the aid of 3D seismic. A 3D seismic survey was acquired and is used to demonstrate a methodology for targeting the Ratcliffe. Other data obtained during the project include oriented core, special formation-imaging log, pressure transient measurements and oil PVT. Although re-entry horizontal drilling was unsuccessfully tested, this completion technology should improve the economic viability of the Ratcliffe. Reservoir simulation of horizontal completions with productivity of three times that of a vertical well suggested two or three horizontal wells in a 258-ha (640-acre) area could recover sufficient reserves for profitable drilling.

  13. Comparison of explosive and vibroseis source energy penetration during COCORP deep seismic reflection profiling in the Williston basin

    Energy Technology Data Exchange (ETDEWEB)

    Steer, D.N.; Brown, L.D.; Knapp, J.H.; Baird, D.J. [Cornell Univ., Ithaca, NY (United States)

    1996-01-01

    Comparison of high-fold (50) vibroseis recordings with coincident low-fold (6) explosive source data from deep reflection surveys in the Williston Basin indicates that while vibroseis generated energy decays to ambient noise levels at 7--9 s two-way traveltime (twtt) (20--30 km depth), energy from explosive sources remains above ambient levels to 35--60 s twtt (105--180 km depth). Moreover, single, moderately sized (30 kg) and well-placed charges proved to be as effective as larger (90 kg) sources at penetrating to mantle traveltimes in this area. However, the explosive source energy proved highly variable, with source-to-ground coupling being a major limiting factor in shot efficacy. Stacked results from the vibroseis sources provide superior imagery of shallow and moderate crustal levels by virtue of greater redundancy and shot-to-shot uniformity; shot statics, low fold, and ray-path distortion across the relatively large (24--30 km aperture) spreads used during the explosive recording have proven to be especially problematic in producing conventional seismic sections. In spite of these complications, the explosive source recording served its primary purpose in confirming Moho truncation and the presence of a dipping reflection fabric in the upper mantle along the western flank of the Trans-Hudson orogen buried beneath the Williston Basin.

  14. The Amaranth Formation of the Williston Basin: Paleomagnetic, Petrologic and Geochemical studies

    Science.gov (United States)

    Szabo, E.; Cioppa, M. T.; Al-Aasm, I.

    2008-12-01

    Major debate continues to exist concerning the time of deposition of the Amaranth Formation in the Williston Basin of North America, with postulated ages of Pennsylvanian, Permian, Triassic, Lower and Middle Jurassic. A multidisciplinary study of the lower member of the Amaranth Formation was conducted in six wells in Manitoba. The lower Amaranth red beds are composed of red carbonate-rich and carbonate-poor interbedded sandstones/siltstones/shales containing dolomite and anhydrite and lacking diagnostic fossils. Preliminary analysis of the oxygen and carbon isotope values measured for replacive and cement dolomite show variations related to particular lithologies that can be correlated to the types of dolomite present in the rocks. The siliciclastic sections are dominated by detrital, zoned dolomite that has recrystallized rims, whereas in the more carbonate-rich and evaporitic samples with little to no clastic content, replacive matrix dolomite is the dominant phase. Dolomite samples from the siliciclastic sections are characterized by relatively depleted carbon and oxygen isotope values, the dolomite matrix samples have relatively enriched oxygen and carbon isotope values and a few samples containing replacement matrix dolomite with minor clastic input have intermediate isotope values. These variations reflect primary and diagenetic overprints. Hematite is the major magnetization carrier, with occasional softer magnetic minerals such as magnetite. Optical microscopy revealed the existence of two types of hematite: detrital specular hematite and very fine red pigment hematite. The paleomagnetic data reveals at least three episodes of magnetization. The most pervasive magnetization, B, was formed during the Permian-Carboniferous Kiaman Reverse Superchron. An isolated magnetization in a couple of wells, C, suggests a remagnetization event that happened sometime between mid-Jurassic and Neogene, possibly resulting from a localized oxidizing fluid flow event. The oldest magnetization, D, was acquired sometime between mid-Devonian and Pennsylvanian, but it is usually poorly defined and is not common within the studied samples. B and D are both carried in both specular and pigmentary hematite and are candidates for a primary magnetization preserved in the lower Amaranth samples. The paleomagnetic data presented in this study indicate that the lower Amaranth member red beds are certainly older than early- to mid-Jurassic, and probably even older than Triassic. Our results suggest that these sediments were deposited either in Pennsylvanian or during the Permian-Carboniferous Kiaman Reverse Superchron.

  15. Reservoir characterization of the Ordovician Red River Formation in southwest Williston Basin Bowman County, ND and Harding County, SD

    Energy Technology Data Exchange (ETDEWEB)

    Sippel, M.A.; Luff, K.D.; Hendricks, M.L.; Eby, D.E.

    1998-07-01

    This topical report is a compilation of characterizations by different disciplines of the Red River Formation in the southwest portion of the Williston Basin and the oil reservoirs which it contains in an area which straddles the state line between North Dakota and South Dakota. Goals of the report are to increase understanding of the reservoir rocks, oil-in-place, heterogeneity, and methods for improved recovery. The report is divided by discipline into five major sections: (1) geology, (2) petrography-petrophysical, (3) engineering, (4) case studies and (5) geophysical. Interwoven in these sections are results from demonstration wells which were drilled or selected for special testing to evaluate important concepts for field development and enhanced recovery. The Red River study area has been successfully explored with two-dimensional (2D) seismic. Improved reservoir characterization utilizing 3-dimensional (3D) and has been investigated for identification of structural and stratigraphic reservoir compartments. These seismic characterization tools are integrated with geological and engineering studies. Targeted drilling from predictions using 3D seismic for porosity development were successful in developing significant reserves at close distances to old wells. Short-lateral and horizontal drilling technologies were tested for improved completion efficiency. Lateral completions should improve economics for both primary and secondary recovery where low permeability is a problem and higher density drilling is limited by drilling cost. Low water injectivity and widely spaced wells have restricted the application of waterflooding in the past. Water injection tests were performed in both a vertical and a horizontal well. Data from these tests were used to predict long-term injection and oil recovery.

  16. 77 FR 9916 - Williston Basin Interstate Pipeline Company; Notice of Request Under Blanket Authorization

    Science.gov (United States)

    2012-02-21

    ...proposes to replace two natural gas-fired 225- horsepower (HP) compressor units installed in 1941, two...500-HP electric compressor unit will also increase the certificated horsepower at the Elk Basin compressor station from...

  17. Geology of the Fox Hills Formation (late Cretaceous) in the Williston Basin of North Dakota, with reference to uranium potential. Report of investigation No. 55

    International Nuclear Information System (INIS)

    The Fox Hills Formation is a marine and brackish sequence of primarily medium and fine clastics within the Late Cretaceous Montana Group. In the Williston basin of North Dakota, four members (in ascending order) are recognized: Trail City, Timber Lake, Iron Lightning (with Bullhead and Colgate lithofacies), and Linton. The Fox Hills conformably overlies the Pierre Shale and conformably and disconformably underlies and interfingers with the Hell Creek Formation; it occurs in about the western two-thirds of the state. The geology of the Fox Hills Formation in North Dakota, and the stratigraphy of which is based on previous surface information and recent subsurface data, are summarized, and its potential for uranium is evaluated

  18. A new species of Ischyodus (Chondrichthyes: Holocephali: Callorhynchidae) from Upper Maastrichtian Shallow marine facies of the Fox Hills and Hell Creek Formations, Williston basin, North Dakota, USA

    Science.gov (United States)

    Hoganson, J.W.; Erickson, J.M.

    2005-01-01

    A new species of chimaeroid, Ischyodus rayhaasi sp. nov., is described based primarily upon the number and configuration of tritors on palatine and mandibular tooth plates. This new species is named in honour of Mr Raymond Haas. Fossils of I. rayhaasi have been recovered from the Upper Maastrichtian Fox Hills Formation and the Breien Member and an unnamed member of the Hell Creek Formation at sites in south-central North Dakota and north-central South Dakota, USA. Ischyodus rayhaasi inhabited shallow marine waters in the central part of the Western Interior Seaway during the latest Cretaceous. Apparently it was also present in similar habitats at that time in the Volga region of Russia. Ischyodus rayhaasi is the youngest Cretaceous species Ischyodus known to exist before the Cretaceous/Tertiary extinction, and the species apparently did not survive that event. It was replaced by Ischyodus dolloi, which is found in the Paleocene Cannonball Formation of the Williston Basin region of North Dakota and is widely distributed elsewhere. ?? The Palaeontological Association.

  19. Manitoba Williston Basin activity update

    Energy Technology Data Exchange (ETDEWEB)

    Fox, J. [Manitoba Industry, Trade and Mines, Winnipeg, MB (Canada)

    2003-07-01

    This presentation described the drilling activity in Manitoba from 1998 to 2002 with particular emphasis on horizontal well drilling and production by geologic formation, including the Bakken, Lodgepole and the Lower Amaranth Formations. A total of 97 wells were drilled in Manitoba in 2002. The most active drillers were EOG Resources Canada with a total of 34 wells. Tundra Oil and Gas was close behind with 28 wells, followed by Chevron Canada Resources with 21 wells. Horizontal drilling had a major impact in Manitoba between 1998-2002, representing 30 per cent of drilling activity focused on the Waskada, Virden and Daly fields. Expansion activity throughout the province contributed to the overall increase in oil production for four consecutive years. Annual production reached 650.7 10{sup 3}m{sup 3} in 2001. Manitoba's top 5 producers are Chevron Canada Resources, Tundra Oil and Gas, EOG Resources Canada, Canadian Natural Resources and NCE Petrofund. Together, they account for 89 per cent of Manitoba's production. This paper also described some of the initiatives that Manitoba's Department of Industry, Trade and Mines has taken to improve oil and gas regulations through proposed amendments to the Oil and Gas Act, a review of the Manitoba Drilling Incentive Program, battery re-permitting, and a strategy for managing orphaned wells. 3 figs.

  20. Lessons to be learned from the Williston Wildcatters Oil Corporation ('Williston') case

    International Nuclear Information System (INIS)

    The chronology and the final outcome of the Herc Oil Corporation deal was described. A creditor (Herc) applied for permission to pursue a creditor-driven plan of arrangement and extend the stay of proceedings of an insolvent oil and gas company (Williston Wildcatters Oil Corp). The plan put forth by Herc was a proposal to acquire all of the assets from the Trustee in return for assuming all of the secured liabilities and paying the amount necessary to satisfy the preferred claims. Unsecured creditors, who would otherwise receive nothing, will receive 49 per cent of the shares of the acquiring company in satisfaction of their claims

  1. Lessons to be learned from the Williston Wildcatters Oil Corporation (`Williston`) case; CD-ROM ed.

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, R.R. [Deloitte and Touche, Guelph, ON (Canada)

    1996-04-01

    The chronology and the final outcome of the Herc Oil Corporation deal was described. A creditor (Herc) applied for permission to pursue a creditor-driven plan of arrangement and extend the stay of proceedings of an insolvent oil and gas company (Williston Wildcatters Oil Corp). The plan put forth by Herc was a proposal to acquire all of the assets from the Trustee in return for assuming all of the secured liabilities and paying the amount necessary to satisfy the preferred claims. Unsecured creditors, who would otherwise receive nothing, will receive 49 per cent of the shares of the acquiring company in satisfaction of their claims.

  2. New aerogeophysical study of the Eurasia Basin and Lomonosov Ridge: Implications for basin development

    DEFF Research Database (Denmark)

    Brozena, J.M.; Childers, V.A.; Lawver, L.A.; Gahagan, L.M.; Forsberg, René; Faleide, J.I.; Eldholm, O.

    2003-01-01

    In 1998 and 1999, new aerogeophysical surveys of the Arctic Ocean's Eurasia Basin produced the first collocated gravity and magnetic measurements over the western half of the basin. These data increase the density and extend the coverage of the U.S. Navy acromagnetic data from the 1970s. The new data reveal prominent bends in the isochrons that provide solid geometrical constraints for plate reconstructions. Tentative identification of anomaly 25 in the Eurasia Basin links early basin opening to...

  3. Implication of drainage basin parameters of a tropical river basin of South India

    Science.gov (United States)

    Babu, K. J.; Sreekumar, S.; Aslam, Arish

    2014-07-01

    Drainage morphometry provides quantitative description of the drainage system which is an important aspect of the characterisation of watersheds. Chalakudi River is one of the important rivers of the South India which has attracted attention of many environmental scientists recently because of the proposed Athirapally Hydel Project across the river. SRTM (Shuttle Radar Topographic Mission) data were used for preparing DEM (Digital Elevation Model), Aspect Map and Slope Map. Geographical Information System (GIS) was used for the evaluation of linear, areal and relief aspects of morphometric parameters. The study reveals that the terrain exhibits dentritic and trellis pattern of drainage. The Chalakudi River Basin has a total area of 1,448.73 km2 and is designated as seventh-order basin. The drainage density of the basin is estimated as 2.54 and the lower-order streams mostly dominate the basin. The high basin relief indicates high runoff and sediment transport. The elongation ratio of the Chalakudi Basin is estimated as 0.48 and indicates that the shape of the basin is elongated. The development of stream segments in the basin area is more or less effected by rainfall. Relief ratio indicates that the discharge capability of watershed is very high and the groundwater potential is meagre. The low value of drainage density in spite of mountainous relief indicates that the area is covered by dense vegetation and resistant rocks permeated by fractures and joints. These studies are helpful in watershed development planning and wise utilization of natural resources.

  4. New aerogeophysical study of the Eurasia Basin and Lomonosov Ridge: Implications for basin development

    DEFF Research Database (Denmark)

    Brozena, J.M.; Childers, V.A.

    2003-01-01

    In 1998 and 1999, new aerogeophysical surveys of the Arctic Ocean's Eurasia Basin produced the first collocated gravity and magnetic measurements over the western half of the basin. These data increase the density and extend the coverage of the U.S. Navy acromagnetic data from the 1970s. The new data reveal prominent bends in the isochrons that provide solid geometrical constraints for plate reconstructions. Tentative identification of anomaly 25 in the Eurasia Basin links early basin opening to spreading in the Labrador Sea before the locus of spreading in the North Atlantic shifted to the Norwegian-Greenland Sea. With the opening of the Labrador Sea, Greenland began similar to200 km of northward movement relative to North America and eventually collided with Svalbard, Ellesmere Island, and the nascent Eurasia ocean basin. Both gravity and magnetic data sets reconstructed to times prior to chron 13 show a prominent linear anomaly oriented orthogonal to the spreading center and immediately north of the YermakPlateau and Morris Jesup Rise. This anomaly may mark the locus of shortening and possibly subduction as Greenland collided with the nascent Eurasia Basin and impinged upon the southern Gakkel Ridge. This collision may have contributed to vollcanism on the Morris Jesup Rise. By chron 13, Greenland had ended its northward motion and had become fixed to North America, and the plateau north of Greenland had rifted apart to become the Morris Jesup Rise and the Yermak Plateau.

  5. Geochemical characterization of Parana Basin volcanic rocks: petrogenetic implications

    International Nuclear Information System (INIS)

    A detailed study of the geochemical characteristics of Parana Basin volcanic rocks is presented. The results are based on the analyses of major and trace elements of 158 samples. Ninety three of these volcanic samples belong to 8 flow sequences from Rio Grande do Sul and Santa Catarina States. The remaining sixty five samples are distributed over the entire basin. In order to study the influence of crustal contamination processes in changing chemical characteristics of the volcanic rocks, 47 samples representative of the crystalline basement of the southern and southeastern Parana Basin were also analysed. Several petrogenetic models were tested to explain the compocional variability of the volcanic rocks, in particular those of southern region. The results obtained sugest an assimilation-fractional crystallization process as viable to explain the differences of both the chemical characteristics and Sr isotope initial ratios observed in basic and intermediate rocks. A model involving melting processes of basic material, trapped at the base of the crust, with composition similar to low and high TiO2 basalts appears to be a possibility to originate the Palmas and Chapeco acid melts, respectively. The study of ''uncontaminated'' or poorly contaminated low TiO2 basic rocks from the southern, central and northern regions shows the existence of significant differences in the geochemical charactetistics according to their geographical occurrence. A similar geochemical diversity is also observed in high TiO2 basalts and Chapeco volcanics. Differences in incompatible element ratios between low and high TiO2 ''uncontaminated'' or poorly contaminated basalts suggest that they could have been produced by different degrees of melting in a garnet peridotite source. Geochemical and isotopic (Sr and Nd) data also support the view that basalts from northern and southern regions of Parana Basin originated from mantle source with different composition. (author)

  6. Structural investigations of Great Basin geothermal fields: Applications and implications

    Energy Technology Data Exchange (ETDEWEB)

    Faulds, James E [Nevada Bureau of Mines and Geology, Univ. of Nevada, Reno, NV (United States); Hinz, Nicholas H. [Nevada Bureau of Mines and Geology, Univ. of Nevada, Reno, NV (United States); Coolbaugh, Mark F [Great Basin Center for Geothermal Energy, Univ. of Nevada, Reno, NV (United States)

    2010-11-01

    Because fractures and faults are commonly the primary pathway for deeply circulating hydrothermal fluids, structural studies are critical to assessing geothermal systems and selecting drilling targets for geothermal wells. Important tools for structural analysis include detailed geologic mapping, kinematic analysis of faults, and estimations of stress orientations. Structural assessments are especially useful for evaluating geothermal fields in the Great Basin of the western USA, where regional extension and transtension combine with high heat flow to generate abundant geothermal activity in regions having little recent volcanic activity. The northwestern Great Basin is one of the most geothermally active areas in the USA. The prolific geothermal activity is probably due to enhanced dilation on N- to NNE-striking normal faults induced by a transfer of NW-directed dextral shear from the Walker Lane to NW-directed extension. Analysis of several geothermal fields suggests that most systems occupy discrete steps in normal fault zones or lie in belts of intersecting, overlapping, and/or terminating faults. Most fields are associated with steeply dipping faults and, in many cases, with Quaternary faults. The structural settings favoring geothermal activity are characterized by subvertical conduits of highly fractured rock along fault zones oriented approximately perpendicular to the WNW-trending least principal stress. Features indicative of these settings that may be helpful in guiding exploration for geothermal resources include major steps in normal faults, interbasinal highs, groups of relatively low discontinuous ridges, and lateral jogs or terminations of mountain ranges.

  7. Compaction of siliceous sediments :Implications for basin modeling and seismic interpretation

    OpenAIRE

    Marcussen, Øyvind

    2009-01-01

    This thesis entitled ?Compaction of siliceous sediments ? Implications for basin modeling and seismic interpretation? has been submitted to the Department of Geosciences at the University of Oslo in agreement with the requirements for the degree of Philosophiae Doctor (Ph.D.) The work presented in this study was completed as part of a large research project funded by The Research Council of Norway within the PETROMAKS program (Program for Optimal Management of Petroleum Resources) entitled ?P...

  8. Waterford Formation in the south-eastern Karoo: Implications for basin development

    Scientific Electronic Library Online (English)

    Bruce S, Rubidge; P. John, Hancox; Richard, Mason.

    Full Text Available Extensive research on the rocks of the Karoo Supergroup has shown that this sequence, which contains an unsurpassed record of Permian-Jurassic tetrapods, records a largely unbroken stratigraphic succession from 300 Ma to 180 Ma. This Gondwanan succession was deposited in a changing environmental set [...] ting reflecting glacial marine through deltaic to fluvial and aeolian desert conditions. The contact between the Ecca and Beaufort Groups (at the top of the Waterford Formation of the Ecca Group) in the southern and western Karoo represents a change in depositional environment from a subaqueous to a subaerial delta plain. By contrast, the Waterford Formation has not yet been recognised in the south-eastern Karoo Basin, which might imply that a major unconformity is present between the Fort Brown Formation of the Ecca Group, deposited in a prodelta environment, and the overlying fluvially deposited Koonap Formation of the Beaufort Group. From careful documentation of lithofacies and sedimentological data, it can be demonstrated that the Waterford Formation is indeed present in the south-eastern part of the basin and that no major unconformity is present - a fact that has implications for the mapping of Karoo rocks in the Eastern Cape Province of South Africa, for understanding the depositional environment of 'reptilian' fossils from the lowermost Beaufort in this part of the Karoo basin, and for basin development models.

  9. How paleosols influence groundwater flow and arsenic pollution: A model from the Bengal Basin and its worldwide implication

    OpenAIRE

    McArthur, J. M.; Ravenscroft, P.; Banerjee, D. M.; Milsom, J.; Hudson-Edwards, K.A.; SENGUPTA, S.; Bristow, C.; Sarkar, A.; Tonkin, S; Purohit, R.

    2008-01-01

    In the Bengal Basin, the land surface exposed during the last lowstand of sea level around 20 ka, and now buried by Holocene sediment, is capped by an effectively impermeable clay paleosol that we term the Last Glacial Maximum paleosol (LGMP). The paleosol strongly affects groundwater flow and controls the location of arsenic pollution in the shallow aquifers of our study site in southern West Bengal and, by implication, in shallow aquifers across the Bengal Basin and As-polluted deltaic aqui...

  10. Archaeological implications of the geology and chronology of the Soa basin, Flores, Indonesia

    Science.gov (United States)

    O'Sullivan, Paul B.; Morwood, Mike; Hobbs, Douglas; Aziz Suminto, Fachroel; Situmorang, Mangatas; Raza, Asaf; Maas, Roland

    2001-07-01

    The timing of arrival of early hominids in Southeast Asia has major implications for models of hominid evolution. The majority of evidence for the earliest appearance of hominids in the region has previously come from Java in western Indonesia. Much of this evidence remains controversial owing to a poor understanding of the stratigraphic and chronologic relationships of the depositional units from which the material was derived. Before artifacts may be placed into their proper archaeological context, the geologic history of archaeological sites must be thoroughly understood, and deposits containing artifacts must be properly dated. An extensive investigation has been undertaken on the island of Flores, in eastern Indonesia, to determine the depositional and chronological history of stratigraphic units within the Soa basin; many of the units are associated with stone artifacts attributed to Homo erectus. Zircon fission-track dates of tuffaceous deposits within this lacustrine basin now provide the most reliable data concerning the true time of arrival of Homo erectus into Southeast Asia and indicate that these early hominids must have successfully begun colonizing eastern Indonesia by ca. 840 ka.

  11. Implications of freshwater flux data from the CMIP5 multimodel output across a set of Northern Hemisphere drainage basins

    Science.gov (United States)

    Bring, Arvid; Asokan, Shilpa M.; Jaramillo, Fernando; Jarsjö, Jerker; Levi, Lea; Pietro?, Jan; Prieto, Carmen; Rogberg, Peter; Destouni, Georgia

    2015-06-01

    The multimodel ensemble of the Coupled Model Intercomparison Project, Phase 5 (CMIP5) synthesizes the latest research in global climate modeling. The freshwater system on land, particularly runoff, has so far been of relatively low priority in global climate models, despite the societal and ecosystem importance of freshwater changes, and the science and policy needs for such model output on drainage basin scales. Here we investigate the implications of CMIP5 multimodel ensemble output data for the freshwater system across a set of drainage basins in the Northern Hemisphere. Results of individual models vary widely, with even ensemble mean results differing greatly from observations and implying unrealistic long-term systematic changes in water storage and level within entire basins. The CMIP5 projections of basin-scale freshwater fluxes differ considerably more from observations and among models for the warm temperate study basins than for the Arctic and cold temperate study basins. In general, the results call for concerted research efforts and model developments for improving the understanding and modeling of the freshwater system and its change drivers. Specifically, more attention to basin-scale water flux analyses should be a priority for climate model development, and an important focus for relevant model-based advice for adaptation to climate change.

  12. Mesozoic history of the Fairway-Aotea Basin: Implications for the early stages of Gondwana fragmentation

    OpenAIRE

    Collot, Julien; Herzer, R. (collab.); Lafoy, Y. (collab.); Geli, Louis

    2009-01-01

    The Fairway Ridge is a buried continental structure that separates the Fairway Basin from the New Caledonia Basin. The proposed Cretaceous age of the Fairway Basin has remained highly hypothetical to date. Deep offshore petroleum exploration wells revealed well-dated Mesozoic carbonaceous sedimentary rocks in the Taranaki Basin at the southern end of the Aotea Basin. In this paper we use geophysical data to confirm the continuity of the 2000 km long Fairway-Aotea Basin connecting New Caledoni...

  13. Transforming river basins: Post-livelihood transition agricultural landscapes and implications for natural resource governance.

    Science.gov (United States)

    Sreeja, K G; Madhusoodhanan, C G; Eldho, T I

    2015-08-15

    The agricultural and livelihood transitions post globalization are redefining resource relations and redrawing landscapes in the Global South and have major implications for nascent natural resource governance regimes such as Integrated River Basin Management (IRBM). A mosaic of divergent reciprocations in resource relations were noticed due to livelihood transitions in the rural areas where previous resource uses and relations had been primarily within agriculture. The reconstitution of rural spaces and the attendant changes in the resource equations are observed to be creating new sites of conformity, contestation and conflicts that often move beyond local spaces. This paper critically reviews studies across the Global South to explore the nature and extent of changes in resource relations and agricultural landscapes post livelihood diversification and the implication and challenges of these changes for natural resource governance. Though there is drastic reduction in agricultural livelihoods throughout the Global South, changes in agricultural area are found to be inconsistent and heterogeneous in the region. Agriculture continues in the countrysides but in widely differentiated capacities and redefined value systems. The transformed agrarian spaces are characterized by a mosaic of scenarios from persistence and sustainable subsistence to differentiation and exploitative commercial practices to abandonment and speculation. The reconfigured resource relations, emergent multiple and multi-scalar interest groups, institutional and policy changes and altered power differentials in these diversified landscapes are yet to be incorporated into natural resource governance frameworks such as IRBM. PMID:26026234

  14. First record of the genus Trichopsomyia Williston, 1888 (Diptera: Syrphidae) from Iran

    OpenAIRE

    KHAGHANINIA, Samad; SHAKERYARI, Abbas; HAYAT, Rüstem

    2012-01-01

    The genus Trichopsomyia Williston, 1888 is recorded for the first time from Iran. Trichopsomyia flavitarsis (Meigen, 1822) and T. lucida (Meigen, 1822) were determined based on the material collected from a wetland in Aynali forests in 2010. A key to the species of the genus in northwestern Iran is prepared and photographs of the specimens are provided.

  15. Climate, Biofuels and Water: Projections and Sustainability Implications for the Upper Mississippi River Basin

    Science.gov (United States)

    Deb, D.; Tuppad, P.; Daggupati, P.; Srinivasan, R.; Varma, D.

    2014-12-01

    Impact of climate change on the water resources of the United States exposes the vulnerability of feedstock-specific mandated fuel targets to extreme weather conditions that could become more frequent and intensify in the future. Consequently, a sustainable biofuel policy should consider a) how climate change would alter both water supply and demand and, b) in turn, how related changes in water availability will impact the production of biofuel crops and c) the environmental implications of large scale biofuel productions. Since, understanding the role of biofuels in the water cycle is key to understanding many of the environmental impacts of biofuels, the focus of this study is on modeling the rarely explored interactions between land use, climate change, water resources and the environment in future biofuel production systems to explore the impacts of the US biofuel policy and climate change on water and agricultural resources. More specifically, this research will address changes in the water demand and availability, soil erosion and water quality driven by both climate change and biomass feedstock production in the Upper Mississippi River Basin. We used the SWAT (Soil and Water Assessment Tool) hydrologic model to analyze the water quantity and quality consequences of land use and land management related changes in cropping conditions (e.g. more use of marginal lands, greater residue harvest, increased yields), plus management practices due to biofuel crops to meet the RFS target on water quality and quantity. Results show that even if the Upper Mississippi River Basin is a region of low water stress, it contributes to high nutrient load in Gulf of Mexico through seasonal shifts in streamflow, changes in extreme high and low flow events, changes in loadings and transport of sediments and nutrients due to changes in precipitation patterns and intensity, changes in frequency of occurrence of floods and drought, early melting of snow and ice, increasing evaporation and changes in soil moisture.

  16. Evolution of the intracratonic Officer Basin, central Australia: implications from subsidence analysis and gravity modelling

    OpenAIRE

    Haddad, D; Watts, Ab; Lindsay, J.

    2001-01-01

    The intracratonic basins of central Australia are distinguished by their large negative Bouguer gravity anomalies, despite the absence of any significant topography. Over the Neoproterozoic to Palaeozoic Officer Basin, the anomalies attain a peak negative amplitude in excess of 150 mGal, amongst the largest of continental anomalies observed on Earth. Using well data from the Officer and Amadeus basins and a data grid of sedimentary thicknesses from the eastern Officer Basin, we have assessed ...

  17. Apatite fission track age of mesozoic sandstones from Beipiao basin, eastern China: Implications for basin provenance and tectonic evolution

    Energy Technology Data Exchange (ETDEWEB)

    Yan Yi; Lin Ge; Wang Yuejun; Guo Feng; Li Zian; Li Xiaoming [Guangzhou Inst. of Geochemistry, Chinese Academy of Sciences, Wushan, Guangzhou (China); Zhao Chongbin [CSIRO, Exploration and mining, Bentley (Australia)

    2003-05-01

    The apatite fission track (FT) analysis of Jurassic sandstones from the Beipiao basin in the eastern China indicates a large variation in FT age peaks. The sandstone of the Beipiao Formation has two peak ages at 178.8 and 40.0 Ma, while the sandstone of the Tuchengzi Formation has three age peaks at 152.0, 77.5 and 32.5 Ma. This implies that the provenance of the Beipiao basin in the early Jurassic and later Jurassic changed obviously. According to the Mesozoic regional thermo-tectonic evolution of the Yan-Liao orogenic belt, these apatites with different FT ages possibly represent different source components, although partial annealing had occurred to these apatites. The apatites of the oldest peak age (178.8-152.0 Ma) possibly originated from the pre-Mesozoic sedimentary covers of the North China Block (NCB), while the apatites of the intermediate peak age (77.5 Ma) and the younger peak age (40.0-32.5 Ma) came from the underlying Archean basement rocks and the Mesozoic volcanic detritus respectively. It is recognized that the basin sediments in the early Jurassic are composed of the Mesozoic volcanic detritus and pre-Mesozoic sedimentary detritus eroded from the uplifted regions around the basin. The existence of the intermediate peak age in the Tuchengzi Formation implies that the Archean basement rocks of the NCB might have become an important source of the upper Jurassic, which responded well to the south-south-east-trending thrust faulting in the northern of the NCB. Apatite FT ages of both the lower and upper Jurassic sediments in the Beipiao basin have a major peak age (30-40 Ma), which perhaps recorded an important Cenozoic thermo-tectonic event accompanied by the intensive rifting, basin subsidence and strong basaltic magmatism in the North China Block. Given a paleo-thermal gradient of 30degC/km, it can be deduced that the Liaoxi area has uplifted about 3 km at an average rate of about 0.1 mm/a since 30-40 Ma. (author)

  18. Basin and Crater Ejecta Contributions to the South Pole-Aitken Basin (SPA) Regolith; Positive Implications for Robotic Surface Samples

    Science.gov (United States)

    Petro, Noah E.; Jolliff, B. L.

    2011-01-01

    The ability of impacts of all sizes to laterally transport ejected material across the lunar surface is well-documented both in lunar samples [1-4] and in remote sensing data [5-7]. The need to quantify the amount of lateral transport has lead to several models to estimate the scale of this effect. Such models have been used to assess the origin of components at the Apollo sites [8-10] or to predict what might be sampled by robotic landers [11-13]. Here we continue to examine the regolith inside the South Pole-Aitken Basin (SPA) and specifically assess the contribution to the SPA regolith by smaller craters within the basin. Specifically we asses the effects of four larger craters within SPA, Bose, Bhabha, Stoney, and Bellinsgauzen all located within the mafic enhancement in the center of SPA (Figure 1). The region around these craters is of interest as it is a possible landing and sample return site for the proposed Moon-Rise mission [14-17]. Additionally, understanding the provenance of components in the SPA regolith is important for interpreting remotely sensed data of the basin interior [18-20].

  19. The thermal history of the Mesozoic Algarve Basin (South Portugal) and its implications for hydrocarbon exploration

    OpenAIRE

    Rodrigues, Bruno; Fernandes, Paulo; Matos, Vasco; Borges, Marisa; Clayton, Geoff

    2012-01-01

    The Algarve Basin is the southernmost geological province of mainland Portugal, outcropping along the entire south coast area and extending offshore, where it is recognised on seismic lines and in hydrocarbon exploration wells. It mainly comprises Jurassic and Lower Cretaceous limestones and marls making a succession over 3 km thick. This sedimentary basin belongs to a series of basins that were initiated by rifting associated with the opening of the North and Central Atlantic ...

  20. Peace/Williston fish and wildlife compensation program: 1992-1993 public compensation report

    International Nuclear Information System (INIS)

    The Peace/Williston Fish and Wildlife Compensation Program is a joint initiative by British Columbia Hydro and the provincial environment ministry to enhance and protect fish and wildlife resources and their habitat in the Williston watershed affected by the construction of the WAC Bennett and Peace Canyon dams on the Peace River. The interest from a fund of $11 million, established by BC Hydro in 1988, is used to maintain the compensation programs. Public input to the ongoing fish and wildlife programs is provided by a public consultation program. To date, the Peace/Williston compensation program has undertaken 93 projects to either conserve or enhance fish and wildlife through habitat improvement and protection. A summary is presented of the activities undertaken by the public consultation program in 1992/93 and public attitudes toward the consultation program. Activities undertaken in the fish and wildlife enhancement program are summarized in appendices. Fisheries programs included stocking, stream fertilization, small lake surveys, preparation of a side channel in Carbon Creek for multi-species spawning, and creation of an artificial spring at Windy Point for spawning purposes. Wildlife programs included channel clearance and vegetation supply improvements to enhance muskrat and beaver habitat; radio monitoring of sheep and elk; studying the feasibility of transplanting elk herds; and purchase of critical ungulate winter habitat lands. 13 figs., 4 tabs

  1. Stratigraphy and structure of Liyue Basin and its implication for South China Sea break-up

    Science.gov (United States)

    Sun, L.; Sun, Z.

    2009-12-01

    Locating in the north of Nansha block, Liyue Basin departed from South China in middle Cenozoic. Experienced four tectonic phases, it is a complicated superimposed basin. Through seismic reflection profile interpretation and drilling as well as dredge sample analysis, we conjectured that there developed Mesozoic and Cenozoic marine deposits. The sedimentary strata are divided into three structural layers by two regional unconformities, which are Late Cretaceous interface and Mid-Miocene interface respectively. The bottom layer is thick Mesozoic sediment, where tilting fault-block and broad fold structures developed. The middle layer is thin rift stage sediment from Palaeocene to mid-Miocene. Absent in uplift area, it displayed typical half graben sediment filling. The top layer is post-rifting marine sediments, continuous and steady. The northeast-trending faults developed in early Cenozoic and controlled the early Cenozoic sediment filling in half graben. These faults indicated that Liyue basin underwent strong tensional tectonic movement above the Mesozoic sedimentary formation. Undergoing the Mesozoic and Cenozoic tectonic evolution, Liyue Basin recorded the transformation process from active margin to passive margin. Through physical and numerical simulation and comparision with Chaoshan depression, we made two conclusions. First,based on previous study results, the Liyue Basin was neighboring Chaoshan depression in Mesozoic, both developed NE-trending wide fold. There are some differences between them too. Reverse faults were revealed in Mesozoic Chaoshan depression but not in Liyue basin. During early Cenozoic, Liyue Basin rifted strongly with many tilt normal faults, while we don’t find rift fault in Chaoshan depression. Considering that the compression in Mesozoic came from the westward subduction of Pacific toward Eurasia, we conjecture that Liyue Basin may locate to the west of Chaoshan depression in Mesozoic, thus the Chaoshan depression underwent stronger compression than Liyue Basin. Second, Liyue Basin located above thinned continental crust before South China Sea opening. The existence of the rigid Reed Bank north of Liyue Basin may be an important factor for basin tectonic evolution. The slightly thinned Reed Bank may cause its northern neighbor areas thinned greatly and caused the cliffy faults developed toward the sea basin. Liyue Basin experienced weak extension and subsidence in Cenozoic.

  2. The significance of Tournaisian tectonism in the Dublin basin: Implications for basin evolution and zinc-lead mineralization in the Irish Midlands

    Science.gov (United States)

    de Morton, Simone N.; Wallace, Malcolm W.; Reed, Christopher P.; Hewson, Chad; Redmond, Patrick; Cross, Eoin; Moynihan, Conor

    2015-12-01

    Recently acquired seismic reflection data, combined with detailed subsurface stratigraphic analysis (core analysis and gamma ray logs) reveal a new view of Lower Carboniferous stratigraphy and tectonism in Ireland. Seismic stratigraphic relationships and stratal thickness variations within Tournaisian units indicates that the Ballinalack High (and associated faulting) was produced by tectonism during the mid to late Tournaisian (Moathill Event, ~ 348 Ma). A second major tectonic event, dominated by regional subsidence (rather than faulting), occurred during the Lower Viséan (Tober Colleen Event, ~ 345 Ma). Each of these tectonic events was associated with major subsidence in the basin, producing strong transgressions within the stratigraphy. We suggest that the Late Tournaisian Moathill Event was responsible for producing the structural setting of the Ballinalack and other Zn-Pb deposits in the Irish Midlands. The suggested earlier timing of fault movement in the basin has implications for arguments about the origin of Irish-type Zn-Pb deposits and the necessity (or not) for having active faulting during mineralization.

  3. Anatomy of a 2nd-order unconformity: stratigraphy and facies of the Bakken formation during basin realignment

    Energy Technology Data Exchange (ETDEWEB)

    Skinner, Orion; Canter, Lyn; Sonnenfeld, Mark; Williams, Mark [Whiting Oil and Gas Corp., Denver, CO (United States)

    2011-07-01

    Because classic Laramide compressional structures are relatively rare, the Williston Basin is often considered as structurally simple, but because of the presence of numerous sub-basins, simplistic lithofacies generalization is impossible, and detailed facies mapping is necessary to unravel Middle Bakken paleogeography. The unconformity above the Devonian Three Forks is explained by the infilling and destruction of the Devonian Elk Point basin, prepares the Bakken system, and introduces a Mississippian Williston Basin with a very different configuration. Black shales are too often considered as deposits that can only be found in deep water, but to a very different conclusion must be drawn after a review of stratigraphic geometry and facies successions. The whole Bakken is a 2nd-order lowstand to transgressive systems tract lying below the basal Lodgepole, which represents an interval of maximal flooding. This lowstand to transgressive stratigraphic context explains why the sedimentary process and provenance shows high aerial variability.

  4. Crustal architecture of the Donets Basin: tectonic implications for diamond and mercury-antimony mineralization

    Science.gov (United States)

    de Boorder, H.; van Beek, A. J. J.; Dijkstra, A. H.; Galetsky, L. S.; Koldewe, G.; Panov, B. S.

    1996-12-01

    Kimberlite-like rocks and minor diamond finds are reported in the Precambrian Ukrainian Shield south of the Donets Basin. Prolific mercury-antimony mineralization occurs in Carboniferous quartz arenites within the Basin. The tectonic setting is examined on the basis of recent data compilations and ongoing research in the Ukraine and Voronezh shield areas and the Pripyat-Dnieper-Donets palaeorift. In the Donets region, a straightforward analogy of any diamond district with the Archangelsk province is not likely in the absence of a Proterozoic shear comparable with the White Sea-Belomorian Mobile Belt. A deep-reaching, NNW-striking lithosphere lineament is identified here as the Kharkov-Donetsk lineament. It transects the rift between the Donets and Dnieper basins. The structures involved in this lineament have controlled Palaeozoic sedimentation and the extent of Late Permian inversion of the Donets basin. During the inversion, the lineament and associated deep-reaching longitudinal structures provided pathways for the migration of mineralizing fluids from deep levels in the lower crust and upper mantle. The intersection, in the Kharkov area, of this lineament with a northeasterly striking lithosphere root should focus diamond exploration towards the northern shoulders of the rift. The extreme attenuation of the crust beneath the Donets Basin, relative to the western basins of the rift, is associated with crustal detachment and subsidence during and possibly after inversion, concomitant with emplacement of asthenospheric materials at higher levels. Together with the continued subsidence in the western Donets Basin, during the Late Permian inversion, this invokes a tectonic setting for the Hg sbnd Sb mineralization not unlike the orogenic-collapse-associated settings of Hg sbnd Sb deposits in western Europe. Further investigation of the geodynamics of the Donets Basin would benefit from deep reflection seismics, petrogenetic studies of magmatic products and their xenoliths, and satellite remote sensing analysis.

  5. Implications of spatial and temporal evolutions of thermal parameters in basin modelling

    OpenAIRE

    L. Amir; Martinez, Luis; Disnar, Jean-Robert; Michels, R.; Vigneresse, J.L.; Robin, C.; Guillocheau, F.

    2008-01-01

    This paper presents the Paris Basin numerical modelling at a high sequential resolution scale (1–5 my). Simulations were carried out from the computation of thermal gradients and conductivities varying with the burial of genetic units. Geologic heating rates are also calculated throughout the burial of the stratigraphic sequences. Thermal energies are then deduced. The Paris Basin is well known for its hydrocarbon potential in Liassic sediments. This study is focused on an east–west cross-sec...

  6. The Messinian record of the outcropping marginal Alborán basin deposits: significance and implications

    OpenAIRE

    Martín, José M.; Braga, Juan C.; Sánchez-Almazo, Isabel

    1999-01-01

    The Messinian record of marginal Alboran basins, such as the Sorbas Basin in southern Spain, consists of a shallow-marine succession with intercalated evaporites. The pre-evaporite sequence comprises a bryozoan-bivalve, temperate-carbonate unit overlain by tropical carbonates. The latter, in turn, consists of two superimposed units: a bioherm unit with coral (Porites, Tarbellastraea, and Siderastraea) and algal (Halimeda) mounds, and a coral (Porites)-stromatolite fringing reef unit. C...

  7. Heavy oil in the central Jeanne d'Arc Basin and implications for exploration risk

    Energy Technology Data Exchange (ETDEWEB)

    Shimeld, J.W.; Moir, P.N. [Natural Resources Canada, Dartmouth, NS (Canada). Geological Survey of Canada; MacRae, R.A.; Fowler, M.G.; Stasiuk, L.D. [Natural Resources Canada, Calgary, AB (Canada). Geological Survey of Canada

    2005-07-01

    The Jeanne d'Arc Basin has the greatest economic potential for oil production from Newfoundland's Grand Banks. It is the deepest of many intracratonic Mesozoic to Cenozoic basins underlying the continental margin. Although most of the oils discovered in the basin are of medium density, 19 per cent of the exploration and delineation wells have shown that some heavy oils with API gravities of less than 25 exist, mostly at depths shallower than 2500 m below the seafloor. Since heavy oils in offshore settings are generally considered to be sub-economic, Late Cretaceous and younger targets in the basin have remained largely untested. Biodegradation is the most prevalent known cause of heavy oil in the basin. Early generation from sulphur-rich source rocks is a secondary cause. Many factors control whether biodegradation can occur. However, in this study area, it was possible to account for all the occurrences of biodegraded heavy oil with an assessment of paleotemperatures alone. Evidence of a 3-phase subsidence history and 2 main periods of hydrocarbon in the Terra Nova, Hebron, and Ben Nevis oilfields have been revealed through the integration of forward basin models, inverse models of apatite fission track lengths, petrography, fluid inclusion studies and geochemistry. The known occurrences of biodegraded heavy oil in the study area has been determined by evaluating paleotemperatures within the subsidence model. The information can be used to accurately predict the possibility of discovering heavy oil elsewhere. 58 refs., 2 tabs., 11 figs.

  8. Dissolved Gas Composition of Groundwater in Taipei Basin and its implications

    Science.gov (United States)

    Cheung, Nga-Chi; Yang, Tsanyao Frank; Chen, Ai-Ti; Chen, Wen-Fu; Wang, Yun-Shuen

    2015-04-01

    This study is the first comprehensive analysis for dissolved gases of groundwater in Taipei Basin, northern Taiwan. In addition to conventional water chemistry, the dissolved-gas compositions of groundwater from 34 observation wells have been systematically analyzed. The relationship between dissolved gases and geological environment, and probable sources of the gases are discussed in this study. According to the water chemistry data of Piper plot, most of the groundwater samples in this study can be classified as Ca(HCO3)2 and NaHCO3 types. Several samples exhibit NaCl type characteristic which reveals the mix with seawater. Isotopic compositions of hydrogen and oxygen for groundwater, surface water and meteoric water in Taipei Basin are aligned with Local Meteoric Water Line (LMWL), which indicates that they are influenced by meteoric water. Composition of groundwater in the southern part of the basin has similar characteristics with surface water. However, stratifications occurred in the observation wells from northern part of the basin. It reveals different recharge sources for groundwater samples in northern basin with the southern basin. Based on the major dissolved gases compositions, three major components are identified which are CH4, N2 and CO2. The d13C of dissolved inorganic carbon (DIC) indicates microbial activities are dominant in the studied area. Dissolved radon concentrations are in the range of 200 - 20,667 Bq/m3 in the studied area and the deeper well usually exhibits a higher radon value than the shallow one from the same site. Several sites with high radon values are correlated with the locations of fault zones, which may provide the conduit for deeper gas migrate to shallower aquifers. The groundwater samples from northern part of the basin exhibit unexpectedly high helium isotopic ratios (RA >2, where RA is the 3He/4He ratio of air). Samples from five observation wells have RA values more than 3 RA and the highest one is 4.2 RA, which probably the highest 3He/4He values ever reported in groundwater samples from basin area. The high RA ratios represent signals from mantle and the source of excess 3He may come from Tatun volcanic group (TVG) which located at the north side of Taipei Basin. Alternatively, the nearby active Shanchiao Fault may provide a pathway for mantle fluids invaded into the basin.

  9. Structural trends in the Cuddapah basin from deep seismic soundings (DSS) and their tectonic implications

    Science.gov (United States)

    Kaila, K. L.; Tewari, H. C.

    1985-05-01

    Structural trends in the upper Proterozoic Cuddapah basin, at the basement level and at the Moho level have been discussed based on Deep Seismic Sounding (DSS) studies. Results of DSS studies along the Alampur-Koniki profile (profile 2 of Fig. 1) crossing the northern part of the Cuddapah basin have been discussed in detail. These results, combined with the results of the Kavali-Paranpalle section of the Kavali-Udipi DSS profile (profile 1 of Fig. 1, Kaila et al., 1979) crossing the basin on its southern flank, along with geological data and earthquake epicentral locations, are used to explain the structural trends of the area. It has been shown that the Cuddapah basin was first created in its western part by downfaulting of the crustal block between faults 7 and 14 towards the west and fault 6 in the east (Fig. 1). Subsequently, the eastern part was downfaulted against fault 6 before the commencement of upper Cuddapah sedimentation. Further downfaulting towards the north along fault 5 created the Srisailam block. Minor-scale downfaulting between faults 7 and 13 in the west and fault 6 in the east and fault 8 in the north gave rise to the Kurnool sub-basin at a later stage. Similar downfaulting east of fault 9 and north of fault 5 gave rise to the Palnad sub-basin. Both these sub-basins received Kurnool sediments. After the close of Kurnool sedimentation, the blocks between faults 4 and 6 along profile II and between 11 and 6 along profile I were uplifted at the basement level, thus giving rise to the Nallamalai hills and Iswarakuppam dome (Fig. 1). The low-angle thrust fault 3 on the eastern margin of the Cuddapah basin might be a post-Cuddapah phenomenon. The low-angle thrust fault 2 probably occurred in the post-Dharwar period. Faults 1, 17 and 10 near the east coast of India seem to be comparatively younger probably of Mesozoic time, along which the coastal block is downfaulted giving rise to the sedimentary basins.

  10. Morphometric Parameters of the Calabar River Basin: Implication for Hydrologic Processes

    OpenAIRE

    Eze Bassey Eze; Joel Efiong

    2010-01-01

    The study examined the morphometric parameters of the Calabar River Basin with emphasis on its implicationfor hydrologic processes. Data for this study were obtained from topographic map which were subject to fieldconfirmation. The result revealed that the basin area was 1 514km2. There were 223 streams with a total streamlength of 516.34km. The textural dissection was considered to be low as drainage density, stream frequency anddrainage intensity values were 0.34km-1, 0.15km-1 and 0.05 resp...

  11. 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 angular unconformity seen widespread over the southern margin of the South China Sea has been interpreted as formed during the Oligocene-Miocene subaerial or submarine erosion process due to its elastic flexural bulging led by gravity load of Palawan-Crocker sedimentary wedge or its collision with Borneo. However, in viewpoint of the significant similarities of Liyue Basin (Reed Bank) and its southwest adjacent waters to Dongsha Basin in their sedimentary architecture, the angular unconformity and open folds underneath, the underlying folded strata there are preferably interpreted as Mesozoic. In fact, Mesozoic sedimentary rocks have been dredged over several sites south nearby the Liyue Basin. Thus, a wide domain of Mesozoic sedimentation might be reconstructed spanning both the conjugated margins.

  12. Isotopic geochemistry in acidic volcanic rocks of the Parana Basin, and associated genetic implications

    International Nuclear Information System (INIS)

    Three samples representatives of the acidic volcanism of the Parana Basin, collected in the States of PR, SC and RS, were dated by Rb-Sr and K-Ar methods. Chemical analyis classify the three occurrences as belonging to the group enriched in phosphorus, titanium and LIL elemets (HPT), compared to the other (LPT) defined for the Parana Basin. Mineral isochrons show the cogeneticity of the components, and the resultant Rb-Sr age is sytematically higher than the value obtained by K-Ar method in the plagioclase phenocrysts. Sr initial ratio indicates a common source for the three occurrences. (Author)

  13. National Assessment of Oil and Gas Project - Williston Basin Province (031) Total Petroleum System

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Total Petroleum System is used in the National Assessment Project and incorporates the Assessment Unit, which is the fundamental geologic unit used for the...

  14. National Assessment of Oil and Gas Project - Williston Basin Province (031) Assessment Units

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Assessment Unit is the fundamental unit used in the National Assessment Project for the assessment of undiscovered oil and gas resources. The Assessment Unit is...

  15. National Assessment of Oil and Gas Project - Williston Basin Province (031) Boundary

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The USGS Central Region Energy Team assesses oil and gas resources of the United States. The onshore and State water areas of the United States comprise 71...

  16. Interpretations from resistivity and lithologic logs in selected wells in the Williston basin

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — These data represent the interpretations from borehole electric (resistivity) logs from oil and gas wells and lithologic logs from nearby water wells. These...

  17. Ultramorphological features of the egg of Telmatoscopus albipunctatus (Williston (Diptera, Psychodidae

    Directory of Open Access Journals (Sweden)

    Thalita Rocha

    2011-06-01

    Full Text Available Ultramorphological features of the egg of Telmatoscopus albipunctatus (Williston (Diptera, Psychodidae. Psychodidae flies, also known as sewage, sand and filter flies are important for medical and veterinary purposes. General information about life cycle and adult habits is available, but few species are known about the egg morphology. Therefore, in this study, the egg ultramorphology of Telmatoscopus albipunctatus (Williston, 1893 was analyzed by scanning electron microscopy to describe its structure, generating data for further comparison between different fly species and genera. General aspects of T. albipunctatus egg are similar to other Psychodidae; egg measuring approximately 0.4 mm in length and 0.1 mm in width. However, based on the continuous and discontinuous longitudinal ridge sculptures observed on the exochorion, which can be species-specific, we can infer that T. albipunctatus eggs can survive under dry or moist conditions, making their control much more difficult. Our data emphasize the advantages of the electron microscope approach in the study of the exochorion patterns. Eggshell morphology of T. albipunctatus can be used as basis for further studies and as a tool to compare different species of Psychodidae flies.Aspectos ultramorfológicos do ovo de Telmatoscopus albipunctatus (Williston (Diptera, Psychodidae. As moscas da família Psychodidae, também conhecidas como moscas de banheiro, são de importância médica e veterinária. Informações gerais sobre ciclo de vida e hábitos do adulto são facilmente encontradas, mas pouco se sabe sobre a morfologia do ovo. Dessa forma, neste estudo, a ultramofologia do ovo de Telmatoscopus albipunctatus (Williston, 1893 foi analisada por microscopia eletrônica de varredura com o objetivo de descrever sua estrutura, provendo importantes dados para futuras comparações entre moscas de diferentes espécies e gêneros. O aspecto geral do ovo de T. albipunctatus é similar a outros Psychodidae, medindo aproximadamente 0.4 mm de comprimento e 0.1 mm de largura. Entretanto, baseado nas esculturas contínuas e descontínuas do exocórion, as quais podem ser espécie-específicas, podemos inferir que os ovos de T. albipunctatus podem sobreviver sob condições de muita umidade ou seca, dificultando o controle da espécie. Nossos resultados ressaltam a importância do uso da microscopia eletrônica como uma ferramenta no estudo dos padrões do exocórion. A morfologia externa do ovo de T. albipunctatus pode ser usada como base para futuros estudos e como ferramenta para comparação de diferentes espécies de moscas do gênero Psychodidae.

  18. Ultramorphological features of the egg of Telmatoscopus albipunctatus (Williston) (Diptera, Psychodidae)

    Scientific Electronic Library Online (English)

    Thalita, Rocha; José Augusto de Oliveira, David; Flávio Henrique, Caetano.

    2011-06-01

    Full Text Available Aspectos ultramorfológicos do ovo de Telmatoscopus albipunctatus (Williston) (Diptera, Psychodidae). As moscas da família Psychodidae, também conhecidas como moscas de banheiro, são de importância médica e veterinária. Informações gerais sobre ciclo de vida e hábitos do adulto são facilmente encontr [...] adas, mas pouco se sabe sobre a morfologia do ovo. Dessa forma, neste estudo, a ultramofologia do ovo de Telmatoscopus albipunctatus (Williston, 1893) foi analisada por microscopia eletrônica de varredura com o objetivo de descrever sua estrutura, provendo importantes dados para futuras comparações entre moscas de diferentes espécies e gêneros. O aspecto geral do ovo de T. albipunctatus é similar a outros Psychodidae, medindo aproximadamente 0.4 mm de comprimento e 0.1 mm de largura. Entretanto, baseado nas esculturas contínuas e descontínuas do exocórion, as quais podem ser espécie-específicas, podemos inferir que os ovos de T. albipunctatus podem sobreviver sob condições de muita umidade ou seca, dificultando o controle da espécie. Nossos resultados ressaltam a importância do uso da microscopia eletrônica como uma ferramenta no estudo dos padrões do exocórion. A morfologia externa do ovo de T. albipunctatus pode ser usada como base para futuros estudos e como ferramenta para comparação de diferentes espécies de moscas do gênero Psychodidae. Abstract in english Ultramorphological features of the egg of Telmatoscopus albipunctatus (Williston) (Diptera, Psychodidae). Psychodidae flies, also known as sewage, sand and filter flies are important for medical and veterinary purposes. General information about life cycle and adult habits is available, but few spec [...] ies are known about the egg morphology. Therefore, in this study, the egg ultramorphology of Telmatoscopus albipunctatus (Williston, 1893) was analyzed by scanning electron microscopy to describe its structure, generating data for further comparison between different fly species and genera. General aspects of T. albipunctatus egg are similar to other Psychodidae; egg measuring approximately 0.4 mm in length and 0.1 mm in width. However, based on the continuous and discontinuous longitudinal ridge sculptures observed on the exochorion, which can be species-specific, we can infer that T. albipunctatus eggs can survive under dry or moist conditions, making their control much more difficult. Our data emphasize the advantages of the electron microscope approach in the study of the exochorion patterns. Eggshell morphology of T. albipunctatus can be used as basis for further studies and as a tool to compare different species of Psychodidae flies.

  19. Implications of climate change for water resources in the Great Lakes basin

    International Nuclear Information System (INIS)

    Several authors have suggested the following impacts of global warming for the Great Lakes region. The average annual warming is predicted by one model to be ca 4.5 degree C, slightly more in winter and slightly less in summer. Annual precipitation is projected to increase by ca 8% for points in the central and western basin, but to decrease by 3-6% for the eastern basin. Basin snowpack could be reduced by up to 100% and the snow season shortened by 2-4 weeks, resulting in a reduction of more than 50% in available soil moisture. Buoyancy-driven turnovers of the water column on four of the six lakes may not occur at all. Presently the phenomena occurs twice per year on all the lakes. Ice formation would be greatly reduced. Maximum ice cover may decline from 72-0% for Lake Superior, 38-0% for Lake Michigan, 65-0% for Lake Huron, 90-50% for Lake Erie and 33-0% for Lake Ontario. Net basin supplies would be reduced probably in the range 15-25% below the current mean value. Possible responses include integrated studies and research, better and continually updated information, assessment of public policies in the U.S. and Canada, enhanced private planning efforts, and increased global cooperation

  20. Quaternary ostracodes and molluscs from the Rukwa Basin (Tanzania) and their evolutionary and paleobiogeographic implications

    Science.gov (United States)

    Cohen, Andrew S.; Van Bocxlaer, Bert; Todd, Jonathan A.; McGlue, Michael; Michel, Ellinor; Nkotagu, Hudson H.; Grove, A.T.; Delvaux, Damien

    2013-01-01

    Much of the spectacular biodiversity of the African Great Lakes is endemic to single lake basins so that the margins of these basins or their lakes coincide with biogeographic boundaries. Longstanding debate surrounds the evolution of these endemic species, the stability of bioprovinces, and the exchange of faunas between them over geologic time as the rift developed. Because these debates are currently unsettled, we are uncertain of how much existing distribution patterns are determined by modern hydrological barriers versus reflecting past history. This study reports on late Quaternary fossils from the Rukwa Basin and integrates geological and paleoecological data to explore faunal exchange between freshwater bioprovinces, in particular with Lake Tanganyika. Lake Rukwa's water level showed large fluctuations over the last 25 ky, and for most of this period the lake contained large habitat diversity, with different species assemblages and taphonomic controls along its northern and southern shores. Comparison of fossil and modern invertebrate assemblages suggests faunal persistence through the Last Glacial Maximum, but with an extirpation event that occurred in the last 5 ky. Some of the molluscs and ostracodes studied here are closely related to taxa (or part of clades) that are currently endemic to Lake Tanganyika, but others testify to wider and perhaps older faunal exchanges between the Rukwa bioprovince and those of Lake Malawi and the Upper Congo (in particular Lake Mweru). The Rukwa Basin has a long history of rifting and lacustrine conditions and, at least temporarily, its ecosystems appear to have functioned as satellites to Lake Tanganyika in which intralacustrine speciation occurred. Paleontological studies of the Rukwa faunas are particularly relevant because of the basin's important role in the late Cenozoic biogeography of tropical Africa, and because many of the molecular traces potentially revealing this history would have been erased in the late Holocene extirpation.

  1. Crustal structure beneath Hudson Bay from ambient-noise tomography: implications for basin formation

    Science.gov (United States)

    Pawlak, Agnieszka; Eaton, David W.; Bastow, Ian D.; Kendall, J. Michael; Helffrich, George; Wookey, James; Snyder, David

    2011-01-01

    The Hudson Bay basin is the least studied of four major Phanerozoic intracratonic basins in North America and the mechanism by which it formed remains ambiguous. We investigate the crustal structure of Hudson Bay based on ambient-noise tomography, using 21 months of continuous recordings from 37 broad-band seismograph stations that encircle the Bay. Green's functions that emerge from the cross correlation of these ambient noise recordings are dominated by fundamental-mode Rayleigh waves. In the microseismic period band (5-20 s), these signals are most prominently expressed in certain preferred azimuths indicative of stationary coastal source regions in southern Alaska and Labrador. Seasonal variations are subtle but consistent with more energetic noise sources during winter months, when wave heights in the Pacific and north Atlantic are larger than in the summer. Noise emanating from Hudson Bay does not appear to contribute significantly to the cross correlograms. Group-velocity dispersion curves are obtained by time-frequency analysis of cross-correlation functions. We test and implement a signal-to-noise ratio (SNR) selection method for producing one-sided cross correlograms, which yields better-defined dispersion ridges than the standard two-sided averaging approach. Tomographic maps and cross sections obtained in the 5-40 s period range reveal significantly lower crustal velocities beneath Hudson Bay than in the bounding Archean Superior craton. The lowest mid-crustal velocities correspond to a previously determined region of maximum lithospheric stretching near the centre of the basin. Pseudosections extracted from the tomographic inversions along profiles across Hudson Bay provide the first compelling direct evidence for crustal thinning beneath the basin. Our results are consistent with a recent estimate of 3 km of crustal thinning, but not consistent with a proposed model for basin subsidence triggered by eclogitization of a remnant crustal root.

  2. Tectono-climatic implications of Eocene Paratethys regression in the Tajik basin of central Asia

    Science.gov (United States)

    Carrapa, Barbara; DeCelles, Peter G.; Wang, Xin; Clementz, Mark T.; Mancin, Nicoletta; Stoica, Marius; Kraatz, Brian; Meng, Jin; Abdulov, Sherzod; Chen, Fahu

    2015-08-01

    Plate tectonics and eustatic sea-level changes have fundamental effects on paleoenvironmental conditions and bio-ecological changes. The Paratethys Sea was a large marine seaway that connected the Mediterranean Neotethys Ocean with Central Asia during early Cenozoic time. Withdrawal of the Paratethys from central Asia impacted the distribution and composition of terrestrial faunas in the region and has been largely associated with changes in global sea level and climate such as cooling associated with the Eocene/Oligocene transition (EOT). Whereas the regression has been dated in the Tarim basin (China), the pattern and timing of regression in the Tajik basin, 400 km to the west, remain unresolved, precluding a test of current paleogeographic models. Here we date the Paratethys regression in Tajikistan at ca. 39 million years ago (Ma), which is several million years older than the EOT (at ca. 34 Ma) marking the greenhouse to icehouse climate transition of the Cenozoic. Our data also show a restricted, evaporitic marine environment since the middle-late Eocene and establishment of desert like environments after ca. 39 Ma. The overall stratigraphic record from the Tajik basin and southern Tien Shan points to deposition in a foreland basin setting by ca. 40 Ma in response to active tectonic growth of the Pamir-Tibet Mountains at the same time. Combined with the northwestward younging trend of the regression in the region, the Tajik basin record is consistent with northward growth of the Pamir and suggests significant tectonic control on Paratethys regression and paleoenvironmental changes in Central Asia.

  3. Irrigation-based livelihood trends in river basins: theory and policy implications for irrigation development

    Science.gov (United States)

    Lankford, Bruce

    This paper examines irrigation development and policy in Tanzania utilising a livelihoods and river basin perspective. On the basis of observations, the author argues that river basins theoretically exhibit a sigmoid curve of irrigation development in three stages; proto-irrigation, irrigation-momentum and river basin management. This model arises from two governing factors. Firstly, irrigation is a complex livelihood activity that, although has benefits, also has costs, risks and alternatives that integrate across many systems; farmers implicitly understand this and enter into or keep out of irrigation accordingly. In the proto-irrigation stage, irrigators are less common, and irrigation is felt to be a relatively unattractive livelihood. In the irrigation-momentum stage, irrigators are drawn very much to irrigation in providing livelihood needs. Hence, given both of these circumstances, governments should be cautious about policies that call for the need to ‘provide irrigation’ (when farmers may not wish to irrigate) or to further increase it (when farmers already have the means and will to do so). Second, irrigation consumes water, generating externalities. Thus if irrigation momentum proceeds to the point when water consumption directly impacts on other sectors and livelihoods, (e.g. pastoralists, downstream irrigation, the environment) decision-makers should focus not necessarily on irrigation expansion, but on water management, allocation and conflict mediation. This three-stage theoretical model reminds us to take a balanced ‘livelihoods river-basin’ approach that addresses real problems in each given stage of river basin development and to develop policy accordingly. The paper contains a discussion on livelihood factors that affect entry into irrigation. It ends with a series of recommendations on policy; covering for example new large-scale systems; problems solving; and the use of an irrigation-river basin livelihoods approach. The recommendations here might be useful for governments and other implementing and donor agencies in Sub-Sahara Africa (where irrigation has greater potential than it currently enjoys) that are considering irrigation as policy instrument for improving rural livelihoods.

  4. Morphology of large impact craters and basins on Venus: Implications for ring formation

    Science.gov (United States)

    Alexopoulos, Jim S.; McKinnon, William B.

    1993-03-01

    A nearly complete examination of the Magellan radar data for the Venusian surface reveals 72 unequivocal peak-ring craters and 4 larger structures that we interpret to be multiringed. This report updates our earlier studies and that of the Magellan team. The general morphology of peak-ring craters, decreasing ring diameter ratio trends with increasing crater diameter, and the general size-morphology progression from complex central-peak crater to peak-ring crater on Venus and the terrestrial planets suggest similar processes of peak-ring formation. Observations are consistent with a model of dynamic collapse, downward and outward, of an unstable central peak to form a ring. We interpret the four larger ringed structures (Klenova, Lise Meitner, Mead, and Isabella) to be morphologically similar to the Orientale Basin on the Moon, and thus, true multiringed basins.

  5. Palaeogeographic implications of differential inclination shallowing in permo-carboniferous sediments from the donets basin, Ukraine

    OpenAIRE

    Iosifidi, Alexandr G.; Mac Niocaill, Conall; Khramov, Alexei N.; Dekkers, Mark J.; Popov, Viktor V.

    2010-01-01

    We present new palaeomagnetic data from Upper Carboniferous and Lower Permian grey and red sediments from the Donets Basin, Ukraine, part of the Palaeozoic East European Platform. Detailed demagnetization of these units reveals two ancient components of magnetization: component "B", which is carried by magnetite and pigmentary haematite, and a high unblocking temperature component "C", present only in the red beds, carried by detrital haematite. The "B" and "C" components both pass fold tests...

  6. Detrital zircon provenance and paleogeography implications for Furnas Formation in the northwest of Paraná Basin

    Directory of Open Access Journals (Sweden)

    Thais Borba Santos

    2015-06-01

    Full Text Available In the northwest of the Paraná Basin, between the states of Mato Grosso and Goiás, there are exposures of the Furnas Formation, where the Transbrasiliano Lineament is also recognized. From the analysis of magnetic maps, the geological and geophysical framework of the study area was defined, with six main domains separated by 5 lineaments. The contact between Paraguay Belt and the Goiás Magmatic Arc is marked by the main direction of the Transbrasiliano Lineament in the study area. Other lineaments that occur associated with the deformation direction of the Paraguay Belt have been identified as a minor component of Transbrasiliano Lineament. The description of outcrops along the northwest border of the Paraná Basin allowed the recognition of units I, II and III of the Furnas Formation. The U-Pb data from detrital zircon from the Furnas Formation showed predominance of grain with Neoproterozoic ages (560 - 800 Ma, with a minimum age of 526 Ma, and the occurrence of grain with Paleoproterozoic (?1750/2100 Ma and Archean (?2700/2800/3100 Ma ages. The study of detrital zircons provenance of the Furnas Formation using U-Pb age determination, associated with the structural framework of the foundation of the basin, and the comparison with paleoenvironmental data were the basis for assessing the paleogeography of the northwestern portion of the Paraná Basin during the aggradation of the Furnas Formation. Ages indicate an important Neoproterozoic contribution similar to the ages of the rocks found in the Goias Magmatic Arc, which associated with data of paleocurrents towards northwest allow us to infer that the arc rocks constituted high terrain, oriented in the NE-SW direction.

  7. Drmno lignite field (Kostolac basin, Serbia): Origin and palaeoenvironmental implications from petrological and organic geochemical studies

    OpenAIRE

    Stojanovi? Ksenija; Životi? Dragana; Šajnovi? Aleksandra; Cvetkovi? Olga; Nytoft Peter Hans; Scheeder Georg

    2012-01-01

    The objective of the study was to determine the origin and to reconstruct the geological evolution of lignites from the Drmno field (Kostolac Basin, Serbia). For this purpose petrological and organic geochemical analyses were used. Coal from the Drmno field is typical humic coal. Peat-forming vegetation dominated by decay of resistant gymnosperm (coniferous) plants, followed by prokaryotic organisms and angiosperms. Coal forming plants belonged to the gymnosperm families Taxodiaceae, Po...

  8. Spatial and temporal variations in precipitation in the Upper Indus Basin, global teleconnections and hydrological implications

    OpenAIRE

    D. R. Archer; H. J. Fowler

    2004-01-01

    Most of the flow in the River Indus from its upper mountain basin is derived from melting snow and glaciers. Climatic variability and change of both precipitation and energy inputs will, therefore, affect rural livelihoods at both a local and a regional scale through effects on summer runoff in the River Indus. Spatial variation in precipitation has been investigated by correlation and regression analysis of long-period records. There is a strong positive correlation between winter precipitat...

  9. Overpressure Evolution during Sedimentary Basin Diagenesis: Implications for Hydrocarbon Transport By Solitary Waves

    Science.gov (United States)

    Joshi, A.; Appold, M. S.

    2014-12-01

    Recent research has shown solitary waves to be capable of transporting fluids through porous media at rates orders of magnitude faster than predicted from Darcy's law. Solitary waves are expressed as regions of high fluid pressure and porosity. The waves form and propagate where permeability is a sensitive function of effective stress, fluid pressure approaches lithostatic pressure, and the rate of fluid pressure generation is rapid compared to the rate of fluid pressure diffusion. The purpose of the present study was to investigate the pressure generation rates that can develop in a sedimentary basin over a range of possible geologic conditions so that the potential for solitary wave formation can be assessed. Pressure generation rates were calculated for a generic sedimentary basin by constructing a two-dimensional numerical model that treated sediment deposition, compaction, heat flow, kerogen maturation, hydrocarbon formation, and the flow of water, oil, and gas. The results showed compaction disequilibrium and hydrocarbon formation to be the two principal causes of pressure generation, respectively. Pressure generation rates for typical sedimentary basinal conditions were found to be on the order of 1's of Pa/year, up to a maximum of ~400 Pa/year under the most favorable pressure generating conditions. These pressure generation rates would be sufficient to form oil-saturated solitary waves but too low to form methane-saturated solitary waves because of the higher rate of methane pressure diffusion compared to oil, due to methane's lower viscosity. To form methane-saturated solitary waves, pressure generation rates of at least ~1800 Pa/year are needed, which are unlikely to be produced by sedimentary basin diagenetic processes, but could possibly be produced by earthquakes.

  10. Upper Jurassic coral communities within siliciclastic settings (Lusitanian Basin, Portugal): Implications for symbiotic and nutrient strategies

    OpenAIRE

    Nose, Martin; Leinfelder, Reinhold

    1997-01-01

    Upper Jurassic coral communities of Portugal (Lusitanian Basin) grew despite high siliciclastic influx. Small, reef-rimmed carbonate platforms existed on basement uplifts over an extended period of time. Other reefs grew whenever episodes of tectonic quiescence and/or rising sea level reduced siliciclastic influx. Reefs grew within a coarse siliciclastic fan delta and on a fine-grained, siliciclastic slope system. The latter is developed as a distally steepened mixed carbonate-siliciclastic r...

  11. Deep seismic reflection study over the Vindhyans of Rajasthan: Implications for geophysical setting of the basin

    Indian Academy of Sciences (India)

    B Rajendra Prasad; V Vijaya Rao

    2006-02-01

    This paper presents results of high-resolution deep seismic re?ection pro?ling of the Proterozoic Vindhyan basin of the Rajasthan area along the Chandli –Bundi –Kota –Kunjer pro ?le.Seismic images have been used to estimate the thickness of Vindhyan strata as well as to understand the tectonic framework of the basin.The results are constrained by gravity,magnetic and magne-totelluric data.The study reveals gentle SE-dipping re?ection bands representing the Vindhyan strata.The seismic sections depict gradual thickening of the Vindhyan succession towards south-east from Bundi.The velocities of the upper and lower Vindhyans are identi?ed as 4.6 –4.8 km/s and 5.1 –5.3 km/s.The NW limit of the Vindhyan basin is demarcated by the Great Boundary Fault (GBF)that manifests as a 30 km wide NW dipping thrust fault extending to a depth of 30 km.

  12. Ultramorphological features of the egg of Telmatoscopus albipunctatus (Williston (Diptera, Psychodidae

    Directory of Open Access Journals (Sweden)

    Thalita Rocha

    2011-06-01

    Full Text Available Ultramorphological features of the egg of Telmatoscopus albipunctatus (Williston (Diptera, Psychodidae. Psychodidae flies, also known as sewage, sand and filter flies are important for medical and veterinary purposes. General information about life cycle and adult habits is available, but few species are known about the egg morphology. Therefore, in this study, the egg ultramorphology of Telmatoscopus albipunctatus (Williston, 1893 was analyzed by scanning electron microscopy to describe its structure, generating data for further comparison between different fly species and genera. General aspects of T. albipunctatus egg are similar to other Psychodidae; egg measuring approximately 0.4 mm in length and 0.1 mm in width. However, based on the continuous and discontinuous longitudinal ridge sculptures observed on the exochorion, which can be species-specific, we can infer that T. albipunctatus eggs can survive under dry or moist conditions, making their control much more difficult. Our data emphasize the advantages of the electron microscope approach in the study of the exochorion patterns. Eggshell morphology of T. albipunctatus can be used as basis for further studies and as a tool to compare different species of Psychodidae flies.

  13. Peace/Williston fish and wildlife compensation program: 1991-1992 Public compensation report

    International Nuclear Information System (INIS)

    The Peace/Williston Fish and Wildlife Compensation Program is a joint initiative by British Columbia Hydro and the provincial environment ministry to enhance and protect fish and wildlife resources and their habitat in the Williston watershed affected by the construction of the WAC Bennett and Peace Canyon dams on the Peace River. The interest from a fund of $11 million, established by BC Hydro in 1988, is used to maintain the compensation programs. Public input to the ongoing fish and wildlife programs is provided by a public consultation program. A summary is presented of the activities undertaken by the public consultation program in 1991/92 and public attitudes toward the consultation program. Activities undertaken in the fish and wildlife enhancement program are summarized in appendices. Fisheries programs included stocking, stream fertilization, small lake surveys, preparation of a side channel in Carbon Creek for multi-species spawning, and creation of an artificial spring at Windy Point for spawning purposes. Wildlife programs included channel clearance and vegetation supply improvements to enhance muskrat and beaver habitat; radio monitoring of sheep and elk; studying the feasibility of transplanting elk herds; and purchase of critical ungulate winter habitat lands. 1 fig., 12 tabs

  14. Basin-Scale Hydrologic Impacts of CO2 Storage: Regulatory and Capacity Implications

    Energy Technology Data Exchange (ETDEWEB)

    Birkholzer, J.T.; Zhou, Q.

    2009-04-02

    Industrial-scale injection of CO{sub 2} into saline sedimentary basins will cause large-scale fluid pressurization and migration of native brines, which may affect valuable groundwater resources overlying the deep sequestration reservoirs. In this paper, we discuss how such basin-scale hydrologic impacts can (1) affect regulation of CO{sub 2} storage projects and (2) may reduce current storage capacity estimates. Our assessment arises from a hypothetical future carbon sequestration scenario in the Illinois Basin, which involves twenty individual CO{sub 2} storage projects in a core injection area suitable for long-term storage. Each project is assumed to inject five million tonnes of CO{sub 2} per year for 50 years. A regional-scale three-dimensional simulation model was developed for the Illinois Basin that captures both the local-scale CO{sub 2}-brine flow processes and the large-scale groundwater flow patterns in response to CO{sub 2} storage. The far-field pressure buildup predicted for this selected sequestration scenario suggests that (1) the area that needs to be characterized in a permitting process may comprise a very large region within the basin if reservoir pressurization is considered, and (2) permits cannot be granted on a single-site basis alone because the near- and far-field hydrologic response may be affected by interference between individual sites. Our results also support recent studies in that environmental concerns related to near-field and far-field pressure buildup may be a limiting factor on CO{sub 2} storage capacity. In other words, estimates of storage capacity, if solely based on the effective pore volume available for safe trapping of CO{sub 2}, may have to be revised based on assessments of pressure perturbations and their potential impact on caprock integrity and groundwater resources, respectively. We finally discuss some of the challenges in making reliable predictions of large-scale hydrologic impacts related to CO{sub 2} sequestration projects.

  15. Comparison of diagenetic fluids in the proterozoic thelon and Athabasca Basins, Canada: implications for protracted fluid histories in stable intracratonic basins

    Energy Technology Data Exchange (ETDEWEB)

    Renac, C. [Univ. de St. Etienne, Dept. de Geologie, Saint Etienne (France); Kyser, T.K.; Durocher, K. [Queen' s Univ., Dept. of Geological Sciences and Geological Engineering, Kingston, Ontario (Canada); Dreaver, G.; O' Connor, T. [Cameco Corp., Saskatoon, SK (Canada)

    2002-01-01

    The Paleoproterozoic Thelon Basin, located on the border between Nunavut and the Northwest Territories of Canada, is a contemporaneous analog of the uranium-rich Paleoproterozoic Athabasca Basin in Canada. Early diagenesis resulted in precipitation of extensive hematite on the surfaces of detrital quartz grains throughout the Thelon Formation and minor hydroxy-phosphate in veins locally. Continued diagenesis then resulted in syntaxial quartz cementation of detrital quartz at 130 degrees C from fluids having ca. 17 wt.% equivalent NaCl, similar to the Athabasca Basin. Cementation of this type is most pronounced in fine-grained sequences in the Thelon Basin. A period of extensive desilicification during continued burial was followed by formation, at ca. 200 degrees C, of peak-diagenetic illite having Ar-Ar ages of ca. 1400-1690 Ma in the Thelon Formation. This illite was associated with fluids with {delta}{sup l8}O and {delta}D values of ca. 6%o and -50%o,respectively, similar to those during peak diagenesis of the Athabasca Basin. Although the timing, salinity, and isotopic composition of the peak-diagenetic fluids in the Thelon and Athabasca Basins are similar, the peak-diagenetic mineral assemblage in the Athabasca Formation is dickite and illite, with minor dravite and goyasite rather than simply illite. Consequently, the fluids at peak diagenesis, which in the Athabasca Basin are synchronous with formation of world-class unconformity-type uranium deposits, had different compositions in each basin. Post-peak diagenesis in the Thelon Basin was quite distinct from that in the Athabasca Basin in that illite was replaced in the central portion of the basin by K-feldspar and then sudoite, which crystallized from saline brines at ca. 1000 Ma and 100 degrees C. Evidence for later infiltration of these brines is absent in the Athabasca Basin, although uranium mobilization at ca. 900 Ma from fluids having the same characteristics as those at peak diagenesis was pronounced in the Athabasca Basin. Recent incursion of meteoric waters along reactivated structures into the Athabasca Basin has variably affected hydrous and uraniferous minerals, but evidence for this is lacking in the Thelon Basin. The Thelon Basin reflects less intensive fluid-rock interaction in its early history than that recorded in the basal units of the Athabasca Basin. (author)

  16. Comparison of diagenetic fluids in the proterozoic thelon and Athabasca Basins, Canada: implications for protracted fluid histories in stable intracratonic basins

    International Nuclear Information System (INIS)

    The Paleoproterozoic Thelon Basin, located on the border between Nunavut and the Northwest Territories of Canada, is a contemporaneous analog of the uranium-rich Paleoproterozoic Athabasca Basin in Canada. Early diagenesis resulted in precipitation of extensive hematite on the surfaces of detrital quartz grains throughout the Thelon Formation and minor hydroxy-phosphate in veins locally. Continued diagenesis then resulted in syntaxial quartz cementation of detrital quartz at 130 degrees C from fluids having ca. 17 wt.% equivalent NaCl, similar to the Athabasca Basin. Cementation of this type is most pronounced in fine-grained sequences in the Thelon Basin. A period of extensive desilicification during continued burial was followed by formation, at ca. 200 degrees C, of peak-diagenetic illite having Ar-Ar ages of ca. 1400-1690 Ma in the Thelon Formation. This illite was associated with fluids with ?l8O and ?D values of ca. 6%o and -50%o,respectively, similar to those during peak diagenesis of the Athabasca Basin. Although the timing, salinity, and isotopic composition of the peak-diagenetic fluids in the Thelon and Athabasca Basins are similar, the peak-diagenetic mineral assemblage in the Athabasca Formation is dickite and illite, with minor dravite and goyasite rather than simply illite. Consequently, the fluids at peak diagenesis, which in the Athabasca Basin are synchronous with formation of world-class unconformity-type uranium deposits, had different compositions in each basin. Post-peak diagenesis in the Thelon Basin was quite distinct from that in the Athabasca Basin in that illite was replaced in the central portion of the basin by K-feldspar and then sudoite, which crystallized from saline brines at ca. 1000 Ma and 100 degrees C. Evidence for later infiltration of these brines is absent in the Athabasca Basin, although uranium mobilization at ca. 900 Ma from fluids having the same characteristics as those at peak diagenesis was pronounced in the Athabasca Basin. Recent incursion of meteoric waters along reactivated structures into the Athabasca Basin has variably affected hydrous and uraniferous minerals, but evidence for this is lacking in the Thelon Basin. The Thelon Basin reflects less intensive fluid-rock interaction in its early history than that recorded in the basal units of the Athabasca Basin. (author)

  17. Hydrogeology of an ancient arid closed basin: Implications for tabular sandstone-hosted uranium deposits

    International Nuclear Information System (INIS)

    Hydrogeologic modeling shows that tabular-type uranium deposits in the grants uranium region of the San Juan basin, New Mexico, formed in zones of ascending and discharging regional ground-water flow. The association of either lacustrine mudstone or actively subsiding structures and uranium deposits can best be explained by the occurrence of lakes at topographic depressions where ground water having different sources and compositions is likely to converge, mix, and discharge. Ascending and discharging flow also explains the association of uranium deposits with underlying evaporites and suggests a brine interface. The simulations contradict previous suggestions that ground water moved downward in the mudflat

  18. Agricultural implications of reduced water supplies in the Green and Upper Yellowstone River Basins

    Energy Technology Data Exchange (ETDEWEB)

    Lansford, R. R.; Roach, F.; Gollehon, N. R.; Creel, B. J.

    1982-02-01

    The growth of the energy sector in the energy-rich but water-restricted Western US has presented a potential conflict with the irrigated agricultural sector. This study measures the direct impacts on farm income and employment resulting from the transfer of water from agriculture to energy in two specific geographical areas - the Green and Upper Yellowstone River Basins. We used a linear programming model to evaluate the impacts of reduced water supplies. Through the use of regional multipliers, we expanded our analysis to include regional impacts. Volume I provides the major analysis of these impacts. Volume II provides further technical data.

  19. Provenance and palaeogeographic implications of Eocene-Oligocene sedimentary rocks in the northwestern Basin and Range

    Science.gov (United States)

    Egger, A.E.; Colgan, J.P.; York, C.

    2009-01-01

    A thick sequence of uppermost Eocene to lower Oligocene volcaniclastic and sedimentary rocks is exposed at the base of the Warner Range in northeastern California. This isolated exposure provides insight into the palaeogeographic setting of the northwestern Basin and Range during this time period. Significant thinning of the unit over 35km of lateral exposure and predominantly volcanic clast compositions suggest that the sequence was deposited in an alluvial plain adjacent to a volcanic arc. Palaeocurrent indicators in the conglomerates define a NNE transport direction. Detrital zircon analysis on coarse sandstones and dating of individual granite cobbles show a range of ages consistent with a local, volcanic source area primarily from the SSW with some far-travelled input from northern Nevada; the far-travelled component increases in influence as the unit thins to the north. Comparison with other sedimentary sequences of Eocene age and integration with palaeofloral and geophysical data help to define drainage divides, and suggest that this sequence accumulated in a relatively isolated, intra-arc basin. This localized accumulation differs markedly from contemporaneous drainages to the south that transported material westwards from central Nevada to the palaeoshoreline, and suggests that ongoing volcanism had a strong influence on palaeogeography in this region during the Eocene and Oligocene.

  20. Modeling fluid flow in sedimentary basins with sill intrusions: Implications for hydrothermal venting and climate change

    Science.gov (United States)

    Iyer, Karthik; Rüpke, Lars; Galerne, Christophe Y.

    2013-12-01

    Large volumes of magma emplaced within sedimentary basins have been linked to multiple climate change events due to release of greenhouse gases such as CH4. Basin-scale estimates of thermogenic methane generation show that this process alone could generate enough greenhouse gases to trigger global incidents. However, the rates at which these gases are transported and released into the atmosphere are quantitatively unknown. We use a 2D, hybrid FEM/FVM model that solves for fully compressible fluid flow to quantify the thermogenic release and transport of methane and to evaluate flow patterns within these systems. Our results show that the methane generation potential in systems with fluid flow does not significantly differ from that estimated in diffusive systems. The values diverge when vigorous convection occurs with a maximum variation of about 50%. The fluid migration pattern around a cooling, impermeable sill alone generates hydrothermal plumes without the need for other processes such as boiling and/or explosive degassing. These fluid pathways are rooted at the edges of the outer sills consistent with seismic imaging. Methane venting at the surface occurs in three distinct stages and can last for hundreds of thousands of years. Our simulations suggest that although the quantity of methane potentially generated within the contact aureole can cause catastrophic climate change, the rate at which this methane is released into the atmosphere is too slow to trigger, by itself, some of the negative ?13C excursions observed in the fossil record over short time scales (<10,000 years).

  1. Gas-and water-saturated conditions in the Piceance Basin, Western Colorado: Implications for fractured reservoir detection in a gas-centered coal basin

    Energy Technology Data Exchange (ETDEWEB)

    Hoak, T.E.; Decker, A.D.

    1995-10-01

    Mesaverde Group reservoirs in the Piceance Basin, Western Colorado contain a large reservoir base. Attempts to exploit this resource base are stymied by low permeability reservoir conditions. The presence of abundant natural fracture systems throughout this basin, however, does permit economic production. Substantial production is associated with fractured reservoirs in Divide Creek, Piceance Creek, Wolf Creek, White River Dome, Plateau, Shire Gulch, Grand Valley, Parachute and Rulison fields. Successful Piceance Basin gas production requires detailed information about fracture networks and subsurface gas and water distribution in an overall gas-centered basin geometry. Assessment of these three parameters requires an integrated basin analysis incorporating conventional subsurface geology, seismic data, remote sensing imagery analysis, and an analysis of regional tectonics. To delineate the gas-centered basin geometry in the Piceance Basin, a regional cross-section spanning the basin was constructed using hydrocarbon and gamma radiation logs. The resultant hybrid logs were used for stratigraphic correlations in addition to outlining the trans-basin gas-saturated conditions. The magnitude of both pressure gradients (paludal and marine intervals) is greater than can be generated by a hydrodynamic model. To investigate the relationships between structure and production, detailed mapping of the basin (top of the Iles Formation) was used to define subtle subsurface structures that control fractured reservoir development. The most productive fields in the basin possess fractured reservoirs. Detailed studies in the Grand Valley-Parachute-Rulison and Shire Gulch-Plateau fields indicate that zones of maximum structural flexure on kilometer-scale structural features are directly related to areas of enhanced production.

  2. Study of the Ouarzazate basin structure by seismic reflection: hydrogeological implications

    Directory of Open Access Journals (Sweden)

    Jaffal, M.

    2009-12-01

    Full Text Available A large number of seismic reflection lines have been carried out in the Ouarzazate basin by the oil industry. The present study is concerned with the interpretation of a part of these data in order to characterize the structure of the Eocene aquifer system. The reflector corresponding to the base of this system, made up of sandstone and limestone, was first identified then digitized on each time-migrated seismic section. An isochrone map of this reflector was realized. The analysis of this map shows that the area under study is subdivided into two structurally contrasted domains. The first, the northern one, is intensively deformed; while the second, the southern one, is slightly folded. The results of this study provide a better understanding of the deep geological structure of the Ouarzazate basin. This allows us to better comprehend the functioning of the Eocene aquifer system, and to rationalize the future potential underground water exploration in the Ouarzazate basin.

    Les campagnes d’exploration pétrolière menées dans le bassin d’Ouarzazate ont permis l’acquisition d’une importante base de données de sismique réflexion. La présente étude concerne l’interprétation d’une partie de ces données dans l’objectif de caractériser la tectonique de l’Eocène et la structure de son système aquifère. Dans un premier temps, le réflecteur correspondant à la base de cet étage, représenté de grès et de calcaires, a été identifié, puis numérisé sur les différentes sections sismiques migrées-temps; ce qui nous a permis d’en établir une carte d’isochrones. Celle-ci montre que le secteur étudié est subdivisé en deux domaines très contrastés d’un point de vue structural. Le premier, septentrional, est affecté par une structuration intense de direction atlasique, tandis que le second, méridional, est faiblement plissé. Les résultats de la présente étude permettent une meilleure connaissance de la structure profonde du bassin d’Ouarzazate. Ceci permet de mieux appréhender le fonctionnement du système aquifère éocène et de rationaliser les futures campagnes de reconnaissance des eaux souterraines susceptibles d’être menées dans le bassin d’Ouarzazate.

  3. Biotic response to late Quaternary rapid climate switches in Santa Barbara Basin: Ecological and evolutionary implications

    International Nuclear Information System (INIS)

    Benthic foraminiferal assemblages from Santa Barbara Basin exhibit major faunal and ecological switches associated with late Quaternary millennial- to decadal-scale global climate oscillations. Repeated turnovers of entire faunas occurred rapidly (<40--400 yr) without extinction or speciation in conjunction with Dansgaard-Oeschger shifts in thermohaline circulation, ventilation, and climate, confirming evolutionary model predictions of Roy et al. Consistent faunal successions of dysoxic taxa during successive interstadials reflect the extreme sensitivity and adaptation of the benthic ecosystem to the rapid environmental changes that marked the late Quaternary and possibly other transitional intervals in the history of the Earth's ocean-atmosphere-cryosphere system. These data support the hypothesis that broad segments of the biosphere are well adapted to rapid climate change

  4. Electrical Conductance Map for the Kachchh Rift Basin: Constraint on Tectonic Evolution and Seismotectonic Implications

    Science.gov (United States)

    Subba Rao, P. B. V.; Arora, B. R.; Singh, A. K.

    2014-09-01

    Geomagnetic field variations recorded by an array of magnetometers spread across the Kachchh Rift basin are reduced to a set of induction arrows as a diagnostic of lateral electrical conductivity variations. A non-uniform thin-sheet electrical conductance model is developed to account for the salient induction patterns. It indicates that the imaged conductivity anomalies can be related to the sediment-filled structural lows in between the fault bounded uplifts. It is suggested that sagging structural lows preserved the marine sediments deposited during the Mesozoic sea transgression and later developed into first order embayment basins for the deposition of sediments in association with Late Eocene transgression. Depth integrated electrical conductance helped in mapping two depo-centres: along the ENE-WSW trending Banni half-Graben bounded by the Kachchh Main fault on the south and, second, along the Vinjan depression formed in response to the subsidence between the Vigodi fault and westward extension of the Katrol Hill fault together with the westward bending of the Median High. Presence of metamorphosed graphite schist clasts in shale dominated Mesozoic sequence and/or thin films of carbon resulting from the thermal influence of Deccan activity on Carbonate-rich formations can account for the high electrical conductivity anomalies seen in the depo-centres of thick Mesozoic and Tertiary sediments. Additionally two high conductivity zones are imaged encompassing a block defined by the 2001 Bhuj earthquake and its aftershocks. In agreement with gravity, magnetic and seismic velocity signatures, aqueous fluids released by recrystallizing magmatic bodies intruded in association with Deccan trap activity account for mapped high conductivity zones. High fluid pressure in such a fractured domain, surrounding the intruded magmatic plugs, perturb the regional stress concentrations to produce frequent and low magnitude aftershocks in the shallow section of the epicentral track of the 2001 Bhuj earthquake.

  5. Modeling Nutrient Release in the Tai Lake Basin of China: Source Identification and Policy Implications

    Science.gov (United States)

    Liu, Beibei; Liu, Heng; Zhang, Bing; Bi, Jun

    2013-03-01

    Because nutrient enrichment has become increasingly severe in the Tai Lake Basin of China, identifying sources and loads is crucial for watershed nutrient management. This paper develops an empirical framework to estimate nutrient release from five major sectors, which requires fewer input parameters and produces acceptable accuracy. Sectors included are industrial manufacturing, livestock breeding (industrial and family scale), crop agriculture, household consumption (urban and rural), and atmospheric deposition. Results show that in the basin (only the five sectors above), total nutrient loads of nitrogen (N) and phosphorus (P) into aquatic systems in 2008 were 33043.2 tons N a-1 and 5254.4 tons P a-1, and annual area-specific nutrient loads were 1.94 tons N km-2 and 0.31 tons P km-2. Household consumption was the major sector having the greatest impact (46 % in N load, 47 % in P load), whereas atmospheric deposition (18 %) and crop agriculture (15 %) sectors represented other significant proportions of N load. The load estimates also indicate that 32 % of total P came from the livestock breeding sector, making it the second largest phosphorus contributor. According to the nutrient pollution sectors, six best management practices are selected for cost-effectiveness analysis, and feasible options are recommended. Overall, biogas digester construction on industrial-scale farms is proven the most cost-effective, whereas the building of rural decentralized facilities is the best alternative under extreme financial constraint. However, the reduction potential, average monetary cost, and other factors such as risk tolerance of policy makers should all be considered in the actual decision-making process.

  6. Seismic Interpretation of Igneous Intrusions and Their Implications for an Unconventional Petroleum System in Southeastern Parnaiba Basin, Northeastern Brazil.

    Science.gov (United States)

    Porto, A. L.; Pereira, E.

    2014-12-01

    After almost two decades of little exploratory effort in the Parnaiba Basin, recent gas discoveries have revived the economic interest in this region. A new exploratory play was successfully tested, confirming the efficiency of the igneous sills triggering the thermal effect on source rocks maturation, and also playing an important role as unconventional trap and seal. Parnaiba Basin was affected by two magmatic events: the Mosquito Formation (Average Age: 178 Ma) and the Sardinha Formation (Average Age: 124 Ma), both characterized by basic magmatic rocks. Ten 2D seismic lines, located in the southeastern Parnaiba Basin, were systematically interpreted in order to identify the main diabase sills geometry, some possible emplacement controls and further implications for an unconventional petroleum system. The identified sills were classified in three types: A, B, and C, according to their dominant geometries and the stratigraphic position of their host rocks. From base to top, Type A sills intrude the Pre-Silurian Sequence, that fills in graben structures of the basement. They have short lateral continuity and saucer-shaped geometry. The main graben faults seem to control the steeper sills, which seem to feed upper sills. Type B sills intrude mainly the Silurian Sequence and have a very long lateral continuity when intruding the shales of Tiangua Formation, in which they are mainly horizontal tabular. Type C sills intrude the top of the Devonian Sequence and have two main geometries: saucer-shaped and horizontal tabular. By correlation to the surface geology of the area, Type C sills are interpreted as Sardinha Formation (Lower Cretaceous). Considering an unconventional hydrocarbon play in the area, some potential trap features associated with sill geometry, were identified, using analogous plays successfully tested in recent discoveries. These traps are associated to a specific sill geometry locally known as "inverted saucer-shaped sill". This shape consists into a horizontal sill placed on the top of a potential reservoir formation, acting also as a seal. On their two tips, this geometry is limited by two steeper sills that may be connected to a lower horizontal sill, which normally intrudes a potential source rock.

  7. Identification of aerosol types over Indo-Gangetic Basin: implications to optical properties and associated radiative forcing.

    Science.gov (United States)

    Tiwari, S; Srivastava, A K; Singh, A K; Singh, Sachchidanand

    2015-08-01

    The aerosols in the Indo-Gangetic Basin (IGB) are a mixture of sulfate, dust, black carbon, and other soluble and insoluble components. It is a challenge not only to identify these various aerosol types, but also to assess the optical and radiative implications of these components. In the present study, appropriate thresholds for fine-mode fraction and single-scattering albedo have been used to first identify the aerosol types over IGB. Four major aerosol types may be identified as polluted dust (PD), polluted continental (PC), black carbon-enriched (BCE), and organic carbon-enriched (OCE). Further, the implications of these different types of aerosols on optical properties and radiative forcing have been studied. The aerosol products derived from CIMEL sun/sky radiometer measurements, deployed under Aerosol Robotic Network program of NASA, USA were used from four different sites Karachi, Lahore, Jaipur, and Kanpur, spread over Pakistan and Northern India. PD is the most dominant aerosol type at Karachi and Jaipur, contributing more than 50% of all the aerosol types. OCE, on the other hand, contributes only about 12-15% at all the stations except at Kanpur where its contribution is ?38%. The spectral dependence of AOD was relatively low for PD aerosol type, with the lowest AE values (1.0). SSA was found to be the highest for OCE (>0.9) and the lowest for BCE (<0.9) type aerosols, with drastically different spectral variability. The direct aerosol radiative forcing at the surface and in the atmosphere was found to be the maximum at Lahore among all the four stations in the IGB. PMID:25893625

  8. A new look at Northwind Ridge: implications for the history of the Canada Basin

    Science.gov (United States)

    Hutchinson, D. R.; Mosher, D. C.; Shimeld, J.; Jackson, R.; Chian, D.; Edwards, B. D.; Hart, P. E.; Mayer, L. A.

    2010-12-01

    Researchers from the US and Canada are conducting collaborative seismic, multibeam, and sampling studies in the mostly ice-covered regions of the Canada Basin (CB) of the Arctic Ocean. Recently acquired data sets, together with older acoustic and coring data, yield new details about the stratigraphic and structural history of CB, particularly regarding its boundary with Northwind Ridge (NR). As previously interpreted, NR represents the eastern edge of a rifted, submerged continental block known as Chukchi Borderland. Gradients along the remarkably linear slope are generally between 10o and 30o, but can be locally as high as ~70o. Water depths across the ridge vary from ~1000 m to ~3800 m. The new data reveal perched half grabens within the escarpment, and numerous complex reflection packages, including at least one possible talus deposit. These deeper reflection packages continue east for ~ 100 km (off northern NR) to ~200 km (off central NR) beneath the oldest on-lapping deposits of CB. This continuity suggests that the shallow basement extending east of NR consists of rocks that may be similar to those on NR, but more highly stretched and therefore more deeply subsided. A low-amplitude positive gravity anomaly coincides with this inferred continental-basement remnant. The profound unconformity at the top of these oldest reflection packages is generally highly reflective, gently sloping, and low relief. This reflection character of basement changes abruptly to high-relief and minimally reflective adjacent to and beneath a distinctive curvilinear gravity low that extends most of the length of CB, previously interpreted as a possible seafloor spreading center. The transition in basement reflection character can be mapped on multiple seismic lines and may represent the basement expression of the final breakup position of the continent (west) to ocean (east) boundary. Two consequences of this possible buried and subsided continental-basement fragment are that (1) models of the opening of CB may not require complete closure and therefore (2) NR may not overlap the continental margin of northern Canada, a problem with previous reconstructions. The northeast orientation of NR is subparallel to the inferred orientation of a deeply buried graben complex that is characterized by a northeast-trending negative gravity anomaly and offset ~250 km to the east of NR. Three northeast-trending bathymetric ridges also occur in the Sever Spur area or CB. Although the ages of rifting for either NR or the deeply buried graben complex are not well constrained, their subparallel orientation suggests this northeast direction is a preferred tectonic fabric either inherited prior to or created during the rifting and opening of the basin.

  9. Hydrothermal speleogenesis in the Eastern Basin and Range Province - Implications for Petroleum and precious-metal exploration

    Energy Technology Data Exchange (ETDEWEB)

    Green, D.J.; Hulen, J.B. (Univ. of Utah Research Institute, Salt Lake City, UT (United States))

    1993-08-01

    Previous investigations based on geometric and textural and analysis have shown that most caverns in the eastern Basin and Range province were excavated not by cool, descending, meteoric waters at or above the water table, but by ascending, moderate-temperature hydrothermal fluids. This conclusion, borne out by fluid-inclusion studies, has important implications for both petroleum and precious-metal exploration in the region. Cavernous porosity has been reported in some of the area's carbonate-hosted oil reservoirs, such as the geothermally active Grant Canyon field in Railroad Valley, as well as in massive carbonates directly beneath some Carlin-type, sediment-hosted gold deposits. Moreover, at virtually all such deposits, hydrothermal carbonate-dissolution (Decalcifcation) is known to be an important porosity-inducing process. Rather than being accidental components of these oil and gold occurrences, the authors contend that such caverns may have formed in the same hydrothermal systems ultimately responsible for petroleum entrapment and precious-metal ultimately responsible for petroleum entrapment and precious-metal mineralization. The fluids that excavated the caverns must have been at least mildly acidic. Carbonic acid is the traditionally cited cavern solvent, but organic and sulfur-based acids thermally generated from regionally prevalent hydrocarbon source rocks, such as the Mississippian Chainman Shale, are equally likely as agents of dissolution. The authors suggest that thermal waters charged with these acids locally may have created or enhanced not only caverns, but migration pathways and depositional sites for gold and oil alike.

  10. Risk of water scarcity and water policy implications for crop production in the Ebro Basin in Spain

    Directory of Open Access Journals (Sweden)

    S. Quiroga

    2010-08-01

    Full Text Available The increasing pressure on water systems in the Mediterranean enhances existing water conflicts and threatens water supply for agriculture. In this context, one of the main priorities for agricultural research and public policy is the adaptation of crop yields to water pressures. This paper focuses on the evaluation of hydrological risk and water policy implications for food production. Our methodological approach includes four steps. For the first step, we estimate the impacts of rainfall and irrigation water on crop yields. However, this study is not limited to general crop production functions since it also considers the linkages between those economic and biophysical aspects which may have an important effect on crop productivity. We use statistical models of yield response to address how hydrological variables affect the yield of the main Mediterranean crops in the Ebro River Basin. In the second step, this study takes into consideration the effects of those interactions and analyzes gross value added sensitivity to crop production changes. We then use Montecarlo simulations to characterize crop yield risk to water variability. Finally we evaluate some policy scenarios with irrigated area adjustments that could cope in a context of increased water scarcity. A substantial decrease in irrigated land, of up to 30% of total, results in only moderate losses of crop productivity. The response is crop and region specific and may serve to prioritise adaptation strategies.

  11. A new early Oligocene mammal fauna from the Sirt Basin, central Libya: Biostratigraphic and paleobiogeographic implications

    Science.gov (United States)

    Coster, Pauline M. C.; Beard, K. Christopher; Salem, Mustafa J.; Chaimanee, Yaowalak; Brunet, Michel; Jaeger, Jean-Jacques

    2015-04-01

    We report the discovery of a new early Oligocene vertebrate fauna from the vicinity of Zallah Oasis in the Sirt Basin of central Libya. The Zallah Incision local fauna has been recovered from the base of a fluvial channel within a rock unit that has been mapped as "Continental and Transitional Marine Deposits." This rock unit has produced fossil vertebrates sporadically since the 1960s, but the Zallah Incision local fauna is the most diverse assemblage of fossil mammals currently known from this unit. In addition to lower vertebrates, the fauna includes an indeterminate sirenian, the anthracothere Bothriogenys, a new species of the hyracoid genus Thyrohyrax, new species of the hystricognathous rodent genera Metaphiomys and Neophiomys, Metaphiomys schaubi, and a new species of the parapithecid primate genus Apidium. The Zallah Incision local fauna from Libya appears to be close in age to Fayum quarries V and G in the Jebel Qatrani Formation of Egypt and the Taqah locality in the Ashawq Formation of Oman. Considered together, these early Oligocene faunas support a modest level of faunal provincialism across the northern part of Afro-Arabia during the early Oligocene.

  12. Globalization and the Spatial Economy: Implications for the Amazon Basin in the 21st Century

    Science.gov (United States)

    Arima, E.; Walker, R.; Richards, P.

    2011-12-01

    Global demand for food and energy will increase in the next decades as world population grows, incomes in developing countries rise, and new energy sources from biofuels are sought. Despite gains in productivity, much of the future demand for those agricultural products will be met by bringing new lands into production. Tropical forests, and in particular the Brazilian Amazon, the focus of our article, are already facing pressures from expanding production of soy, beef, cotton, and biofuels as deforestation advances the agricultural frontier. This article begins by reviewing the recent literature and provides evidences of indirect land cover change in the Amazon driven by the tandem soy - cattle, whereby mechanized agriculture encroaches on existing pastures, displacing them to the Amazonian frontier. We then consider conditions in the spatial economy that potentially inhibit ongoing forest loss. In particular, we address the prospect of forest transition in the Amazon basin. This necessitates a review of the so-called Borlaug hypothesis, and the circumstances under which land sparing occurs. Land sparing, a sufficient if not necessary condition for forest transition, represents a potential solution to environmental problems associated with land change, one that promotes sustainability by furthering rural development with improved technologies. The paper concludes by contrasting the current Brazilian agricultural and environmental policies with the conditions set in the previous section.

  13. Palaeogeographic implications of differential inclination shallowing in permo-carboniferous sediments from the donets basin, Ukraine

    Science.gov (United States)

    Iosifidi, Alexandr G.; Mac Niocaill, Conall; Khramov, Alexei N.; Dekkers, Mark J.; Popov, Viktor V.

    2010-07-01

    We present new palaeomagnetic data from Upper Carboniferous and Lower Permian grey and red sediments from the Donets Basin, Ukraine, part of the Palaeozoic East European Platform. Detailed demagnetization of these units reveals two ancient components of magnetization: component "B", which is carried by magnetite and pigmentary haematite, and a high unblocking temperature component "C", present only in the red beds, carried by detrital haematite. The "B" and "C" components both pass fold tests indicating a primary or a near primary-origin for magnetizations. The "C" component, however, yields palaeolatiudes that are consistently lower (by up to ˜ 12° of latitude or ˜ 1330 km) than those derived from the "B" component, and we argue that this is due to significant inclination-shallowing of the "C"-component. A comparison with European reference palaeomagnetic data reveals that the reference data also span a large spread of palaeolatitudes for this time, and we argue that unrecognized shallowing may have crept into the reference data when based on sedimentary units. A more rigorous approach to selecting reference palaeomagnetic data may well be key to resolving palaeogeographic controversies at this time.

  14. Isotopic composition of rainfall and runoff in a small arid basin with implications for deep percolation

    International Nuclear Information System (INIS)

    The aim of this work was to characterize the isotopic composition of potential recharge in an arid rocky watershed. Unique field observations were obtained from an arid watershed in the Negev Highlands, Israel, through utilization of the dynamic variations in the isotopic composition of rainfall and runoff. The hydrological system's inputs are rainfall and its isotopic composition. Rainfall and runoff were sampled in eight storms. High variability in the isotopic composition of rainfall was observed during any single rainstorm. The isotopic distribution in the runoff at the outlet of the basin appeared often not to be correlated to the isotopic patterns of the associated rain storm. A new mathematical model was developed to describe these physical processes. The model called A Double-Component Kinematic Wave Flow and Transport Approach, was designated to assess the dynamic isotopic distribution in arid rain storms and runoff. This model simulates the transport of rainfall into overland flow and runoff in an arid rocky watershed with uniformly distributed shallow depression storage. A numerical solution for the problem was developed, to estimate the depression storage parameters. The model also reflects the isotopic memory effect due to the depression storage between sequential rain showers. A good agreement between the observed and computed hydrograph and the change of the ?18O values in runoff in time confirms the validity of the model. (author) 138 figs., 125 refs

  15. Parascolymia (Scleractinia: Lobophylliidae) in the Central Paratethys Sea (Vienna Basin, Austria) and its possible biogeographic implications

    Science.gov (United States)

    Reuter, Markus; Wiedl, Thomas; Piller, Werner E.

    2015-01-01

    Palaeobiogeographical and palaeodiversity patterns of scleractinian reef corals are generally biased due to uncertain taxonomy and a loss of taxonomic characters through dissolution and recrystallization of the skeletal aragonite in shallow marine limestones. Herein, we describe a fossil lobophylliid coral in mouldic preservation from the early middle Miocene Leitha Limestone of the Central Paratethys Sea (Vienna Basin, Austria). By using grey-scale image inversion and silicone rubber casts for the visualization of the original skeletal anatomy and the detection of distinct micromorphological characters (i.e. shape of septal teeth, granulation of septocostae) Parascolymia bracherti has been identified as a new species in spite of the dissolved skeleton. In the recent era, Parascolymia like all Lobophylliidae is restricted to the Indo-Pacific region, where it is represented by a single species. The new species proves the genus also in the Miocene Mediterranean reef coral province. A review of the spatio-temporal relationships of fossil corals related to Parascolymia indicates that the genus was probably rooted in the Eastern Atlantic?Western Tethys region during the Paleocene to Eocene and reached the Indo-Pacific region not before the Oligocene. The revealed palaeobiogeographical pattern shows an obvious congruence with that of Acropora and tridacnine bivalves reflecting a gradual equatorwards retreat of the marine biodiversity center parallel to the Cenozoic climate deterioration. PMID:26201071

  16. Spatial variation of the aftershock activity across the Kachchh Rift Basin and its seismotectonic implications

    Indian Academy of Sciences (India)

    A P Singh; O P Mishra; Dinesh Kumar; Santosh Kumar; R B S Yadav

    2012-04-01

    We analyzed 3365 relocated aftershocks with magnitude of completeness (Mc) ? 1.7 that occurred in the Kachchh Rift Basin (KRB) between August 2006 and December 2010. The analysis of the new aftershock catalogue has led to improved understanding of the subsurface structure and of the aftershock behaviour. We characterized aftershock behaviour in terms of -value, -value, spatial fractal dimension ($D_s$), and slip ratio (ratio of the slip that occurred on the primary fault and that of the total slip). The estimated -value is 1.05, which indicates that the earthquake occurred due to active tectonics in the region. The three dimensional -value mapping shows that a high -value region is sandwiched around the 2001 Bhuj mainshock hypocenter at depths of 20–25 km between two low -value zones above and below this depth range. The $D_s$-value was estimated from the double-logarithmic plot of the correlation integral and distance between hypocenters, and is found to be 2.64 ± 0.01, which indicates random spatial distribution beneath the source zone in a two-dimensional plane associated with fluid-filled fractures. A slip ratio of about 0.23 reveals that more slip occurred on secondary fault systems in and around the 2001 Bhuj earhquake (Mw 7.6) source zone in KRB.

  17. Delineation of Piceance Basin basement structures using multiple source data: Implications for fractured reservoir exploration

    Energy Technology Data Exchange (ETDEWEB)

    Hoak, T.E.; Klawitter, A.L.

    1995-10-01

    Fractured production trends in Piceance Basin Cretaceous-age Mesaverde Group gas reservoirs are controlled by subsurface structures. Because many of the subsurface structures are controlled by basement fault trends, a new interpretation of basement structure was performed using an integrated interpretation of Landsat Thematic Mapper (TM), side-looking airborne radar (SLAR), high altitude, false color aerial photography, gas and water production data, high-resolution aeromagnetic data, subsurface geologic information, and surficial fracture maps. This new interpretation demonstrates the importance of basement structures on the nucleation and development of overlying structures and associated natural fractures in the hydrocarbon-bearing section. Grand Valley, Parachute, Rulison, Plateau, Shire Gulch, White River Dome, Divide Creek and Wolf Creek fields all produce gas from fractured tight gas sand and coal reservoirs within the Mesaverde Group. Tectonic fracturing involving basement structures is responsible for development of permeability allowing economic production from the reservoirs. In this context, the significance of detecting natural fractures using the intergrated fracture detection technique is critical to developing tight gas resources. Integration of data from widely-available, relatively inexpensive sources such as high-resolution aeromagnetics, remote sensing imagery analysis and regional geologic syntheses provide diagnostic data sets to incorporate into an overall methodology for targeting fractured reservoirs. The ultimate application of this methodology is the development and calibration of a potent exploration tool to predict subsurface fractured reservoirs, and target areas for exploration drilling, and infill and step-out development programs.

  18. Regional medicine use in the Rhine basin and its implication on water quality

    Science.gov (United States)

    Hut, R. W.; Houtman, C. J.; van de Giesen, N. C.; de Jong, S. A. P.

    2012-04-01

    Do Germans use more painkillers than the French? Pharmaceuticals used in our Western society form an important group of contaminants found in the river Rhine. As this river is the drinking water source for millions of Europeans, methods to investigate relations between drug use and their penetration in the watercycle are of great importance. An analysis is presented relating medicine residue in the river Rhine to the number of people living in its watershed. An extensive measuring campaign was carried out, sampling river Rhine at 42 locations from its source to the start of its delta (Dutch-German border). The samples were analyzed for 40 common pharmaceuticals. Using discharge data, digital elevation models and demographic data from Eurostat, the relation between total load of drug residue and population was analyzed. Results show regional differences in drug use as well as implications for (down)stream water quality concerning contamination with pharmaceuticals.

  19. 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.

  20. The Rock Paintings of Williston :an interpretative study of rock art, rituals and the landscape in which they are created

    OpenAIRE

    Hykkerud, Martin Kristoffer

    2006-01-01

    The Williston district in Northern Cape, offers an exciting and new contribution to the rich world of rock art in South Africa. The paintings found here are solely geometric finger paintings, with a variety of different images and motifs. There are possible connections between these paintings and the initiation ceremonies of the Khoekhoen, once pejoratively known as the Hottentots. The main motif and link between the rock art and these rituals, is the so-called ‘apron motif’. These image...

  1. Stratigraphic distribution of macerals and biomarkers in the Donets Basin: Implications for paleoecology, paleoclimatology and eustacy

    Energy Technology Data Exchange (ETDEWEB)

    Izart, A.; Elie, M.; Alsaab, D. [UMR 7566G2R, Universite Henri Poincare, BP239, F-54506, Vandoeuvre-les-Nancy (France); Sachsenhofer, R.F.; Rainer, T.; Sotirov, A.; Zdravkov, A. [Institut fuer Geowissenschaften, Montanuniversitaet Leoben, A-8700 Leoben (Austria); Privalov, V.A.; Antsiferov, V.A. [Donetsk National Technical University, Artem str. 58, UA-83000 Donetsk (Ukraine); Panova, E.A. [UkrNIMI, National Academy of Science of Ukraine, Tchelyuskintsev str. 291, UA-83121 Donetsk (Ukraine); Zhykalyak, M.V. [Donetsk State Regional Geological Survey, Sybirtseva str. 17, UA-84500 Artemovsk (Ukraine)

    2006-02-03

    More than one hundred and thirty coal seams and coaly layers occur in the Donets Basin (Donbas). Twenty-eight (52 samples) of them, ranging in age from Serpukhovian (Late Mississipian) to Gzhelian (Late Pennsylvanian), 33 clastics and three limestones were studied in terms of maceral composition, sulphur contents, and biomarker distribution. Diterpanes are used to estimate the contribution of different groups of plants and the height of the water table in the swamp; hopanes are a measure of bacterial activity in the peat; and steranes indicate the relative input of wood and algae. Stratigraphic trends in these parameters are discussed in relation to paleoenvironment, climatic changes, and eustacy. A tropical climate prevailed in the Donbas from Serpukhovian to Kasimovian times. Nevertheless, periods with drier and wetter conditions can be distinguished based on maceral and biomarker data. Relatively dry conditions are observed during Serpukhovian and Vereian times, whereas wetter climates with a maximum of coal deposition occurred during the (late) Bashkirian, most of the Moscovian, and the earliest Kasimovian. No economic coal seams are hosted in upper Kasimovian and Gzhelian deposits, a result of a change to an arid climate. Our data also suggest climatic changes during sequences of different order. For the second-order, third-order, and fourth-order sequences, relatively dry or wet conditions occurred during coal deposition in the lowstand systems tract, an intermediate climate during the transgressive systems tract and the maximum flooding, and a wet climate during the highstand systems tract. The results for high frequency sequences support the Cecil's paleoclimatic model: an intermediate paleoclimate during LST (sandstone and levee siltstone), a wet climate during early TST (coal), and a dry climate during late TST (limestone), MFS (claystone), and HST (deltaic siltstone). Coals deposited during maximum flooding periods are more enriched in C{sub 27} steranes derived from algae, and contain lower proportions of C{sub 29} steranes derived from the wood of higher plants. (author)

  2. Stratigraphic distribution of macerals and biomarkers in the Donets Basin: Implications for paleoecology, paleoclimatology and eustacy

    International Nuclear Information System (INIS)

    More than one hundred and thirty coal seams and coaly layers occur in the Donets Basin (Donbas). Twenty-eight (52 samples) of them, ranging in age from Serpukhovian (Late Mississipian) to Gzhelian (Late Pennsylvanian), 33 clastics and three limestones were studied in terms of maceral composition, sulphur contents, and biomarker distribution. Diterpanes are used to estimate the contribution of different groups of plants and the height of the water table in the swamp; hopanes are a measure of bacterial activity in the peat; and steranes indicate the relative input of wood and algae. Stratigraphic trends in these parameters are discussed in relation to paleoenvironment, climatic changes, and eustacy. A tropical climate prevailed in the Donbas from Serpukhovian to Kasimovian times. Nevertheless, periods with drier and wetter conditions can be distinguished based on maceral and biomarker data. Relatively dry conditions are observed during Serpukhovian and Vereian times, whereas wetter climates with a maximum of coal deposition occurred during the (late) Bashkirian, most of the Moscovian, and the earliest Kasimovian. No economic coal seams are hosted in upper Kasimovian and Gzhelian deposits, a result of a change to an arid climate. Our data also suggest climatic changes during sequences of different order. For the second-order, third-order, and fourth-order sequences, relatively dry or wet conditions occurred during coal deposition in the lowstand systems tract, an intermediate climate during the transgressive systems tract and the maximum flooding, and a wet climate during the highstand systems tract. The results for high frequency sequences support the Cecil's paleoclimatic model: an intermediate paleoclimate during LST (sandstone and levee siltstone), a wet climate during early TST (coal), and a dry climate during late TST (limestone), MFS (claystone), and HST (deltaic siltstone). Coals deposited during maximum flooding periods are more enriched in C27 steranes derived from algae, and contain lower proportions of C29 steranes derived from the wood of higher plants. (author)

  3. Differentiation of the South Pole-Aitken basin impact melt sheet: Implications for lunar exploration

    Science.gov (United States)

    Hurwitz, Debra M.; Kring, David A.

    2014-06-01

    We modeled the differentiation of the South Pole-Aitken (SPA) impact melt sheet to determine whether noritic lithologies observed within SPA formed as a result of the impact. Results indicate differentiation of SPA impact melt can produce noritic layers that may accommodate observed surface compositions but only in specific scenarios. One of nine modeled impact melt compositions yielded layers of noritic materials that account for observations of noritic lithologies at depths of ~6 km. In this scenario, impact occurred before a hypothesized lunar magma ocean cumulate overturn. The 50 km deep melt sheet would have formed an insulating quenched layer at the surface before differentiating. The uppermost differentiated layers in this scenario have FeO and TiO2 contents consistent with orbital observations if they were subsequently mixed with the uppermost quenched melt layer and with less FeO- and TiO2-enriched materials such as ejecta emplaced during younger impacts. These results verify that noritic lithologies observed within SPA could have formed as a direct result of the impact. Therefore, locations within SPA that contain noritic materials represent potential destinations for collecting samples that can be analyzed to determine the age of the SPA impact. Potential destinations include central peaks of Bhabha, Bose, Finsen, and Antoniadi craters, as well as walls of Leibnitz and Schrödinger basins. Additionally, potential remnants of the uppermost quenched melt may be preserved in gabbroic material exposed in "Mafic Mound." Exploring and sampling these locations can constrain the absolute age of SPA, a task that ranks among the highest priorities in lunar science.

  4. Is there a remnant Variscan subducted slab in the mantle beneath the Paris basin? Implications for the late Variscan lithospheric delamination process and the Paris basin formation

    Science.gov (United States)

    Averbuch, O.; Piromallo, C.

    2012-08-01

    The Paris basin (northern France) is a Late Paleozoic-Mesozoic intracratonic basin that settled upon the collapsed Variscan collisional belt. The lithospheric roots of the Variscan orogenic system, below the Paris basin, have been investigated using a European-scale P-wave velocity tomographic model. Tomography points out the existence of a significant high velocity anomaly in the upper mantle below the western part of the basin. At ~ 150-200 km depth, the anomaly extends with a NW-SE trend along the buried Northern France trace of the Northern Variscan Suture Zone i.e. the Bray segment of the Upper Carboniferous Lizard-Rhenohercynian (LRH) suture. Moreover, the high-velocity anomaly is spatially correlated with the prominent Paris Basin Magnetic Anomaly. Its downdip extent reaches depths greater than 200 km below the southern margin of the Paris basin. As suggested in previous tomographic studies below ancient suture zones, these data argue for such anomaly being the remnant of a Variscan subducted slab that escaped the extensive late orogenic delamination process affecting the lithospheric roots by Late Carboniferous-Early Permian times and that was preserved stable over 300 Ma at the base of the lithosphere. On a general geodynamical perspective, these results provide a new insight into the long-term evolution of subducted lithosphere into the mantle. In the case of the Western European Variscan orogenic belt, they suggest that the subduction of the LRH slab below the previously thickened Variscan crust, and its final detachment from the orogenic root, have played an important role in the collapse of the belt, inducing thermal erosion and extension of the overriding lithosphere. The spatial evolution of late orogenic extension across the belt and of subsequent thermal subsidence in the Paris basin is suggested to result from the heterogeneous delamination of the lithospheric roots along strike and from the resultant pattern of asthenospheric rise.

  5. Earthquake geology of Kashmir Basin and its implications for future large earthquakes

    Science.gov (United States)

    Shah, A. A.

    2013-02-01

    Two major traces of active thrust faults were identified in the Kashmir Basin (KB) using satellite images and by mapping active geomorphic features. The ~N130°E strike of the mapped thrust faults is consistent with the regional ~NE-SW convergence along the Indian-Eurasian collision zone. The ~NE dipping thrust faults have uplifted the young alluvial fan surfaces at the SW side of the KB. This created a major tectono-geomorphic boundary along the entire strike length of the KB that is characterised by (1) a low relief with sediment-filled sluggish streams to the SE and (2) an uplifted region, with actively flowing streams to the SW. The overall tectono-geomorphic expression suggests that recent activity along these faults has tilted the entire Kashmir valley towards NE. Further, the Mw 7.6 earthquake, which struck Northern Pakistan and Kashmir on 8 October 2005, also suggests a similar strike and NE dipping fault plane, which could indicate that the KB fault is continuous over a distance of ~210 km and connects on the west with the Balakot Bagh fault. However, the geomorphic and the structural evidences of such a structure are not very apparent on the north-west, which thus suggest that it is not a contiguous structure with the Balakot Bagh fault. Therefore, it is more likely that the KB fault is an independent thrust, a possible ramp on the Main Himalayan Thrust, which has uplifting the SW portion of the KB and drowning everything to the NE (e.g. Madden et al. 2011). Furthermore, it seems very likely that the KB fault could be a right stepping segment of the Balakot Bagh fault, similar to Riasi Thrust, as proposed by Thakur et al. (2010). The earthquake magnitude is measured by estimating the fault rupture parameters (e.g. Wells and Coppersmith in Bull Seismol Soc Am 84:974-1002, 1994). Therefore, the total strike length of the mapped KB fault is ~120 km and by assuming a dip of 29° (Avouac et al. in Earth Planet Sci Lett 249:514-528, 2006) and a down-dip limit of 20 km, a Mw of 7.6 is possible on this fault.

  6. Trends in the Annual Frequency of Atlantic Basin Intense Hurricanes: Implications for the Near-Term

    Science.gov (United States)

    Wilson, Robert M.

    1998-01-01

    During the interval of 1944-1997, 120 intense hurricanes (category 3, 4, or 5 on the Saffir-Simpson hurricane scale) have been observed in the Atlantic basin. These intense hurricanes have had an observed annual frequency of 0-7 events per year (having a mean, mode, and median equal to about 2 events per year), being preferentially lower during El Ninio years and higher during non-El Ninio years. Also, it has recently been established that a long-term downward trend in the annual frequency of intense hurricanes, spanning about five decades, has taken place, although this trend can, alternatively, be explained as a shift from a more active state prior to the mid 1960's to a less active state thereafter (rather than as a simple linear decline). In this paper, on the basis of 10-yr moving averages, the long4erm trend of the frequency of intense hurricanes is compared against one for the annual mean temperature at Armagh Observatory, Northern Ireland (which serves as a proxy for climatic change). Interestingly, the two sets of 10-yr moving averages correlate extremely well, especially, when incorporating a slight 6-yr lag between them (with temperature leading; r = 0.90). This suggests that the current leading trend of temperature, which had been downward, but now is upward, may portend a return to the more active state for intense hurricanes. Thus, the 1998 season (presuming the abatement of El Ninio prior to the start of the hurricane season), and for several years thereafter (at least, into the early years of the next millennium), may have an annual frequency of intense hurricanes that is commensurate with the previously observed active state that was seen prior to the mid 1960's. If true, then, the shift to the more active state, probably, occurred in the mid-to-late 1980's, apparently, having gone undetected because of the masking, or modulating, effect of El Ninio, which has been rampant since the mid-to-late 1980's.

  7. Spatial and seasonal responses of precipitation in the Ganges and Brahmaputra river basins to ENSO and Indian Ocean dipole modes: implications for flooding and drought

    Science.gov (United States)

    Pervez, Md Shahriar; Henebry, Geoffry M.

    2015-01-01

    We evaluated the spatial and seasonal responses of precipitation in the Ganges and Brahmaputra basins as modulated by the El Niño Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) modes using Global Precipitation Climatology Centre (GPCC) full data reanalysis of monthly global land-surface precipitation data from 1901 to 2010 with a spatial resolution of 0.5° × 0.5°. The GPCC monthly total precipitation climatology targeting the period 1951–2000 was used to compute gridded monthly anomalies for the entire time period. The gridded monthly anomalies were averaged for the years influenced by combinations of climate modes. Occurrences of El Niño alone significantly reduce (88% of the long-term average (LTA)) precipitation during the monsoon months in the western and southeastern Ganges Basin. In contrast, occurrences of La Niña and co-occurrences of La Niña and negative IOD events significantly enhance (110 and 109% of LTA in the Ganges and Brahmaputra Basin, respectively) precipitation across both basins. When El Niño co-occurs with positive IOD events, the impacts of El Niño on the basins' precipitation diminishes. When there is no active ENSO or IOD events (occurring in 41 out of 110 years), precipitation remains below average (95% of LTA) in the agriculturally intensive areas of Haryana, Uttar Pradesh, Rajasthan, Madhya Pradesh, and Western Nepal in the Ganges Basin, whereas precipitation remains average to above average (104% of LTA) across the Brahmaputra Basin. This pattern implies that a regular water deficit is likely, especially in the Ganges Basin, with implications for the agriculture sector due to its reliance on consistent rainfall for successful production. Historically, major droughts occurred during El Niño and co-occurrences of El Niño and positive IOD events, while major flooding occurred during La Niña and co-occurrences of La Niña and negative IOD events in the basins. This observational analysis will facilitate well-informed decision making in minimizing natural hazard risks and climate impacts on agriculture, and supports development of strategies ensuring optimized use of water resources in best management practice under a changing climate.

  8. Spatial and seasonal responses of precipitation in the Ganges and Brahmaputra river basins to ENSO and Indian Ocean dipole modes: implications for flooding and drought

    Science.gov (United States)

    Pervez, M. S.; Henebry, G. M.

    2015-01-01

    We evaluated the spatial and seasonal responses of precipitation in the Ganges and Brahmaputra basins as modulated by the El Niño Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) modes using Global Precipitation Climatology Centre (GPCC) full data reanalysis of monthly global land-surface precipitation data from 1901 to 2010 with a spatial resolution of 0.5° × 0.5°. The GPCC monthly total precipitation climatology targeting the period 1951-2000 was used to compute gridded monthly anomalies for the entire time period. The gridded monthly anomalies were averaged for the years influenced by combinations of climate modes. Occurrences of El Niño alone significantly reduce (88% of the long-term average (LTA)) precipitation during the monsoon months in the western and southeastern Ganges Basin. In contrast, occurrences of La Niña and co-occurrences of La Niña and negative IOD events significantly enhance (110 and 109% of LTA in the Ganges and Brahmaputra Basin, respectively) precipitation across both basins. When El Niño co-occurs with positive IOD events, the impacts of El Niño on the basins' precipitation diminishes. When there is no active ENSO or IOD events (occurring in 41 out of 110 years), precipitation remains below average (95% of LTA) in the agriculturally intensive areas of Haryana, Uttar Pradesh, Rajasthan, Madhya Pradesh, and Western Nepal in the Ganges Basin, whereas precipitation remains average to above average (104% of LTA) across the Brahmaputra Basin. This pattern implies that a regular water deficit is likely, especially in the Ganges Basin, with implications for the agriculture sector due to its reliance on consistent rainfall for successful production. Historically, major droughts occurred during El Niño and co-occurrences of El Niño and positive IOD events, while major flooding occurred during La Niña and co-occurrences of La Niña and negative IOD events in the basins. This observational analysis will facilitate well-informed decision making in minimizing natural hazard risks and climate impacts on agriculture, and supports development of strategies ensuring optimized use of water resources in best management practice under a changing climate.

  9. Assessing the implications of baseline climate uncertainty on simulated water yield within the Himalayan Beas river basin in NW India

    Science.gov (United States)

    Holman, I.; Remesan, R.; Adeloye, A.; Ojha, C. S.

    2013-12-01

    Understanding the impacts of the changing water cycle on future water resources and society is one of the most important issues surrounding anthropogenic climate change, especially in regions with limited adaptive capacity or highly water-dependent economies. One such region is the north western Himalayan region of India, where supplementary irrigation is used in the non-monsoon seasons and where over 90% of the population are reliant on agriculture for their livelihoods. This paper focuses on the transboundary 12,560km2 Beas catchment in Himachal Pradesh, which is one of the case study catchments of the Mitigating the Impacts of Climate Change in Indian agriculture (MICCI) project of the UK NERC Changing Water Cycle Programme. However, understanding of the impacts of changes in the water cycle in such regions is dependent on the quality of available observational climate datasets- a challenge given the relative paucity of ground-based observations in mountainous terrains. River flows in the Beas, which support both irrigation and hydropower, are highly seasonal, being dependent on the Indian Monsoon augmented by seasonal snow and ice melt from the Himalayas. This paper describes the uncertainty in simulating water yield in the Beas catchment, using the HySim hydrological model, associated with the use of a diverse range of public domain and governmental observed and derived precipitation and evapo-transpiration datasets (including gridded ground-based data from the Indian Meteorological Department; TRMM, NCEP Climate Forecast System Reanalysis (CFSR) and the APHRODITE project). For example, basin annual average precipitation (2000-07) ranges from 1476 mm/yr (CFSR), 2093mm/yr (APHRODITE) to 2357 mm/yr (TRMM), whilst basin annual average reference evapotranspiration ranges from 1320 mm/yr (with a minimum to maximum sub-basin range of 136-4680 mm/yr) using the Priestley Taylor to 2296 mm/yr (190-6954 mm/yr) with Penman-Monteith. The selection of datasets affects baseline hydrological model performance with, for example, calibration Nash-Sutcliffe Efficiencies ranging from 0.56 to 0.68 across the precipitation datasets (using CFSR data to derive evapotranspiration) for the river Beas. To evaluate the potential impact of such uncertainty on assessments of future water yield, we further describe the application of a scenario-neutral modelling framework using IPPC AR4 ranges of temperature and precipitation changes to the baseline datasets to assess the differences in their response surfaces. The results show that the uncertainty in the driving hydroclimatological variables, associated with the choice of underlying observational dataset and the choice of evopo-transpiration method, translates into significant temporal and spatial uncertainty in simulated baseline and future water yield with significant implications for our ability to project changes in the water cycle in such sensitive regions.

  10. Structure and sediment budget of Yinggehai-Song Hong basin, South China Sea: Implications for Cenozoic tectonics and river basin reorganization in Southeast Asia

    Science.gov (United States)

    Lei, Chao; Ren, Jianye; Sternai, Pietro; Fox, Matthew; Willett, Sean; Xie, Xinong; Clift, Peter D.; Liao, Jihua; Wang, Zhengfeng

    2015-08-01

    The temporal link between offshore stratigraphy and onshore topography is of key importance for understanding the long-term surface evolution of continental margins. Here we present a grid of regional, high-quality reflection seismic and well data to characterize the basin structure. We identify fast subsidence of the basin basement and a lack of brittle faulting of the offshore Red River fault in the Yinggehai-Song Hong basin since 5.5 Ma, despite dextral strike-slip movement on the onshore Red River fault. We calculate the upper-crustal, whole-crustal, and whole-lithospheric stretching factors for the Yinggehai-Song Hong basin, which show that the overall extension observed in the upper crust is substantially less than that observed for the whole crust or whole lithosphere. We suggest that fast basement subsidence after 5.5 Ma may arise from crustal to lithospheric stretching by the regional dynamic lower crustal/mantle flow originated by collision between India-Eurasia and Indian oceanic subduction below the Eurasian margin. In addition, we present a basin wide sediment budget in the Yinggehai-Song Hong basin to reconstruct the sedimentary flux from the Red River drainage constrained by high-resolution age and seismic stratigraphic data. The sediment accumulation rates show a sharp increase at 5.5 Ma, which suggests enhanced onshore erosion rates despite a slowing of tectonic processes. This high sediment supply filled the accommodation space produced by the fast subsidence since 5.5 Ma. Our data further highlight two prominent sharp decreases of the sediment accumulation at 23.3 Ma and 12.5 Ma, which could reflect a loss of drainage area following headwater capture from the Paleo-Red River. However, the low accumulation rate at 12.5 Ma also correlates with drier and therefore less erosive climatic conditions.

  11. Integrated Analysis on Gravity and Magnetic Fields of the Hailar Basin, NE China: Implications for Basement Structure and Deep Tectonics

    Science.gov (United States)

    Sun, B.; Wang, L.; Dong, P.; Scientific Team Of Applied Geophysics

    2010-12-01

    The Hailar Basin is one of the most representative basins among the Northeast China Basin Group, which is situated in the east of East Asia Orogene between the Siberia Plate and the North China Plate. Based on the detailed analysis of the Bouguer gravity anomaly, aeromagnetic anomaly as well as petrophysical data, we studied the features of gravity-magnetic fields in the basin and its neighboring areas. A combined approach of Wavelet Multi-scale Decomposition and Power Spectrum Analysis was adopted to quantitatively grade the gravity and magnetic anomalies into four levels. Accordingly, the apparent depths of the source fields can be assessed. The results reveal the crustal density and magnetic structures of the Hailar Basin. Low-order wavelet details of gravity-magnetic anomalies were carried out on studying basin basement structure. Seven major basement faults of the basin were identified, and the basement lithology was discussed and predicted. Three major uplifts and 14 depressions were delineated according to basement depth inversion by the Park method. High-order wavelet approximations of gravity-magnetic anomalies were carried out on studying deep tectonics of the basin. The average Moho depth of the study area is about 40 km, with a mantle uplift located in the northeast of the basin. The average depth of the Curie interface is about 19 km, while the uplift of the Curie interface is in the basin center and its east and west sides are depressions. Finally, inversion of Bouguer gravity anomalies was conducted on an across-basin GGT profile using the Wavelet Multi-scale Decomposition. The inversion results are consistent with those of GGT seismic inversion, suggesting that the Wavelet Multi-scale Decomposition can be applied to distinguish major crustal density interfaces.

  12. The structural evolution of the Ghadames and Illizi basins during the Paleozoic, Mesozoic and Cenozoic: Petroleum implications

    Energy Technology Data Exchange (ETDEWEB)

    Gauthier, F.J. [Anadarko Petroleum Corp., Houston, TX (United States); Boudjema, A. [Somatrach, Algiers (Algeria); Lounis, R. [Anadarko Algeria Corp., Houston, TX (United States)

    1995-08-01

    The Ghadames and Illizi basins cover the majority of the eastern Sahara of Algeria. Geologicaly, this part of the Central Saharan platform has been influenced by a series of structural arches and {open_quotes}moles{close_quotes} (continental highs) which controlled sedimentation and structure through geologic time. These features, resulting from and having been affected by nine major tectonic phases ranging from pre-Cambrian to Tertiary, completely bound the Ghadames and Illizi Basins. During the Paleozoic both basins formed one continuous depositional entity with the Ghadames basin being the distal portion of the continental sag basin where facies and thickness variations are observed over large distances. It is during the Mesozoic-Cenozoic that the Ghadames basin starts to evolve differently from the Illizi Basin. Eustatic low-stand periods resulted in continental deposition yielding the major petroleum-bearing reservoir horizons (Cambrian, Ordovician, Siluro-Devonian and Carboniferous). High-stand periods corresponds to the major marine transgressions covering the majority of the Saharan platform. These transgressions deposited the principal source rock intervals of the Silurian and Middle to Upper Devonian. The main reservoirs of the Mesozoic and Cenozoic are Triassic sandstone sequences which are covered by a thick evaporite succession forming a super-seal. Structurally, the principal phases affecting this sequence are the extensional events related to the breakup of Pangea and the Alpine compressional events. The Ghadames and Illizi basins, therefore, have been controlled by a polphase tectonic history influenced by Pan African brittle basement fracturing which resulted in complex structures localized along the major basin bounding trends as well as several subsidiary trends within the basin. These trends, as demonstrated with key seismic data, have been found to contain the majority of hydrocarbons trapped.

  13. Eocene to Miocene back-arc basin basalts and associated island arc tholeiites from northern Sulawesi (Indonesia): Implications for the geodynamic evolution of the Celebes basin

    International Nuclear Information System (INIS)

    Eocene BABB basalts intruded by tholeiitic and calk-alkalic island arc magmatic rocks are reported from the north arm of Sulawesi (Indonesia). Age and geochemical similarities between these basalts and those drilled in the Celebes Sea indicate this North Sulawesi volcanic arc was built on the same oceanic crust. The 25 deg late Neogene clockwise rotation of the north arm of Sulawesi following its collision with fragments of Australia (Sula, Buton) is not sufficient to explain the asymmetrical magnetic anomalies in the Celebes basin. The North Sulawesi island arc could be interpreted as having progressively retreated northward on its own Celebes sea back arc basin, during an episode of Palaeogene-early Neogene tectonic erosion along the trench. (authors)

  14. Hydrocarbon Potentials, Thermal and Burial History in Herwa-1 Well from the Nigerian Sector of the Chad Basin: An Implication of 1-D Basin Modeling Study

    Directory of Open Access Journals (Sweden)

    Abubakar Mijinyawa

    2013-06-01

    Full Text Available This research study attempt to evaluate the hydrocarbon potentials, thermal and burial history and the timing of hydrocarbon generation in Herwa-1 well within the Nigerian Sector of the Chad basin. Organic geochemical study of some ditch cuttings samples from Herwa-1 well and a One-dimensional basin modeling study was carried out. The result of the geochemical analysis revealed a moderate to good TOC greater than 0.5wt% in Fika and Gongila formation, the Hydrogen Index (HI ranges from 150-300 (mgHC/g and the Tmax values falls within the range of greater than or equal to 430°C. The hydrocarbon potentials in Herwa-1 well was further supported with the values of S1+S2 which is greater than or equal to 2 mg/g of rock in almost all the samples, suggesting a good hydrocarbon potentials. The 1-D basin model was constructed for Herwa-1 well in order to assess the burial history and thermal maturity of the potential source rocks in the Nigerian sector of the Chad basin. The modeling results indicate that maximum burial occurred in the late Miocene and suggesting erosion might have been the cause of the thinning of the Tertiary sediments in the present time. The calibration of Vitrinite reflectance against Temperature revealed the present day heat flow to be at 60 mW/m2 and Paleo heat flow falls within the range of 68 mW/m2. However, it is also revealed that Oil Window begins at (0.60-1.30% VRr at the depth of (2000-3000 m in the middle Cretaceous and the Gas Window start during the late Cretaceous to Tertiary with a value of (1.3-2.5% VRr at a depth greater than (3500 m.

  15. Provenance of Cretaceous-Oligocene Sedimentary Strata of the Floresta Basin, Eastern Cordillera, Colombia and Tectonic Implications

    Science.gov (United States)

    Saylor, J.; Corredor, J.; Mora, A.; Horton, B. K.; Nie, J.

    2010-12-01

    We use integrated detrital zircon U-Pb geochronology, sandstone petrography, sedimentary facies analysis, and paleocurrent measurements from a Mesozoic-Cenozoic clastic succession preserved in the northern Andean fold-thrust belt to address foreland-basin disruption in the Paleogene. The Floresta basin is situated along the axis of the Eastern Cordillera of Colombia. Detrital zircon U-Pb ages and sandstone petrography indicate that the Floresta basin first received sediment from the eastern craton (Guyana shield) in the Cretaceous-early Paleocene and then from the western magmatic arc (Central Cordillera) starting in the mid-Paleocene. The upper-crustal magmatic arc was replaced by a metamorphic basement source, which we identify as Magdalena valley basement equivalent, in the middle Eocene. This, in turn, was replaced by an upper-crustal thrust-belt source in the late Eocene which persisted until Oligocene truncation of the Cenozoic section by the eastward advancing Soapaga thrust. This upper crustal source is interpreted to represent uplift of the western flank of the Eastern Cordillera. The combined provenance data indicates that sediments were derived from eastward-migrating sources. Throughout the Paleogene, paleocurrent and sediment provenance data point to a uniform western or southwestern sediment source with no evidence of the complex sourcing or sediment dispersal patterns emblematic of a broken foreland basin. Therefore, these data show that the Floresta basin existed as part of a laterally extensive, unbroken foreland basin connected with the western (Magdalena) basin from Cretaceous to late Eocene time, when it was isolated by uplift of the western flank of the Eastern Cordillera. The Floresta basin was also connected with the eastern (Llanos) basin from the Cretaceous until its late Oligocene truncation by the advancing thrust front.

  16. Sr-Nd-Hf-Pb isotope geochemistry of basaltic rocks from the Cretaceous Gyeongsang Basin, South Korea: Implications for basin formation

    Science.gov (United States)

    Choi, S.; Kwon, S.; Lee, D.

    2013-12-01

    To better understand the formative mechanism of the Cretaceous Gyeongsang Basin in South Korea, we determined the geochemical compositions of Early Cretaceous syntectonic basaltic rocks intercalated with basin sedimentary assemblages. Two distinct compositional groups appeared: tholeiitic to calc-alkaline basalts from the Yeongyang sub-basin and high-K to shoshonitic basaltic trachyandesites from the Jinju and Uiseong sub-basins. All collected samples exhibit patterns of light rare earth element enrichment and chondrite-normalized (La/Yb)N ratios ranging from 2.4 to 23.6. In a primitive-mantle-normalized spidergram, the samples show distinctive negative anomalies in Nb, Ta, and Ti and a positive anomaly in Pb. The basalts exhibit no or a weak positive U anomaly in a spidergram, but the basaltic trachyandesites show a negative U anomaly. The basalts have highly radiogenic Sr [(87Sr/86Sr)i = 0.70722-0.71145], slightly negative ?Nd, positive ?Hf [(?Nd)i = -2.7 to 0.0; (?Hf)i = +2.9 to +6.4], and radiogenic Pb isotopic compositions [(206Pb/204Pb)i = 18.20-19.19; (207Pb/204Pb)i = 15.60-15.77; (208Pb/204Pb)i = 38.38-39.11]. The basaltic trachyandesites are characterized by radiogenic Sr [(87Sr/86Sr)i = 0.70576-0.71119] and unradiogenic Nd, Hf, and Pb isotopic compositions [(?Nd)i = -14.0 to -1.4; (?Hf)i = -17.9 to +3.7; (206Pb/204Pb)i = 17.83-18.25; (207Pb/204Pb)i = 15.57-15.63; (208Pb/204Pb)i = 38.20-38.70]. The 'crust-like' signatures, such as negative Nb-Ta anomalies, elevated Sr isotopic compositions, and negative ?Nd(t) and ?Hf(t) values, of the basaltic trachyandesites resemble the geochemistry of Early Cretaceous mafic volcanic rocks from the southern portion of the eastern North China Craton. Considering the lower-crust-like low U/Pb and high Th/U ratios and the unradiogenic Pb isotopic compositions, the basaltic trachyandesites are considered to be derived from lithospheric mantle modified by interaction with melts that originated from foundered eclogite. Basaltic volcanism in the Yeongyang sub-basin is coeval with the basaltic trachyandesite magmatism, but it exhibits an elevated 87Sr/86Sr ratio at a given 143Nd/144Nd and highly radiogenic Pb isotopic compositions, which imply an origin from an enriched but heterogeneous lithospheric mantle source. Melts from subducted altered oceanic basalt and pelagic sediments are considered to be the most likely source for the metasomatism. An extensional tectonic regime induced by highly oblique subduction of the Izanagi Plate beneath the eastern Asian margin during the Early Cretaceous might have triggered the opening of the Gyeongsang Basin. Lithospheric thinning and the resultant thermal effect of asthenospheric upwelling could have caused melting of the metasomatized lithospheric mantle, producing the Early Cretaceous basaltic volcanism in the Gyeongsang Basin.

  17. Implications for the Formation of Transform Faults from Pliocene Basins on Isla San Jose, Southern Gulf of California

    Science.gov (United States)

    Umhoefer, P. J.; Schwennicke, T.; Ingle, J. C.; Del Margo, M. T.; Ruiz-Geraldo, G.

    2001-12-01

    Pliocene basins on islands in the southern Gulf of California offer a superb opportunity to evaluate how transform faults form in a highly oblique plate boundary. Pliocene strata are exposed in two subbasins on Isla San Jose, 100 km north of La Paz, Mexico. The subbasins have broadly similar stratigraphy and part of the basin is subsided offshore. A ~1 km thick lower sequence deepens upward from a thick alluvial fan unit through marginal marine strata to an outer shelf to upper slope mudstone (based on lithology and benthic forams). The uppermost mudstone has planktonic forams that indicate an early late Pliocene age ( ~3.5-3 Ma). There is evidence for widespread syn-sedimentary deformation in the lower sequence. The upper sequence is a ~50 - 120 m thick shallow marine calcarenite that lies across a low-angle to abruptly gradational unconformity. The overall stratigraphy represents 1 - 1.5 km of subsidence in the lower sequence before 3 Ma, followed by local tilting of the basin and rapid upward shallowing at and after 3 Ma. A late Pliocene to Quaternary unconformity lies above the basin and most Quaternary deposits are alluvial. The southern subbasin is bounded by NW-N striking Pliocene normal and normal-dextral faults, while the northern subbasin has mainly buttress unconformities and local faults along an irregular embayment. The subbasins on Isla San Jose may have initiated at the northern end of an early transform fault emanating from the Cerralvo trough, which suggests basin inception at 5 - 6 Ma. This implies a reasonable rate of subsidence for a rift basin. The rapid basin uplift indicates a major reorientation (or cessation) of Cerralvo transform faulting at ~3 Ma. Mudstone deposition at 3.5 - 3 Ma followed by basin uplift is similar to events in the Perico basin on Isla Carmen, 120 km to the NW near Loreto. These synchronous events on two separate islands may mean that the development of early transform faults acted in unison from Loreto to the mouth of the Gulf. This implies that there was a major reorganization of early transform faults to the modern configuration at 3 Ma. In contrast, later fault reorientation in the Loreto basin at 2.4 - 2 Ma suggests that there may be a northward propagation of transform fault development. The evidence from the islands shows that MCS and bathymetric data from the narrow shelf are needed to resolve the connections from the basins and faults we are studying on the islands to the main plate boundary transform spreading ridge system in the middle of the Gulf of California.

  18. Palynology and age of the Early Oligocene units in Cardak-Tokca Basin, Southwest Anatolia: Paleoecological implications

    Energy Technology Data Exchange (ETDEWEB)

    Akkiraz, M.S.; Akgun, F. [Dokuz Eylul University, Izmir (Turkey)

    2005-06-01

    In this study, the lignite bearing sediments of Cardak-Tokca basin exposed in southwest Anatolia, were palynologically examined. A well preserved and diverse palynomorph assemblage indicating an Early Oligocene age was recovered from the Hayrettin and Tokca formations. The palynomorph assemblage is dominated by Pinus, Sparganiaceae, Juglandaceae and diverse tricolpate and tricolporate pollen. In addition a few species of marine dinoflagellate cysts were encountered as well. The Early Oligocene age is based primarily on the presence of stratigraphic markers such as: Boehlensipollis hohli, Slowakipollis hippophaeoides, Aglaoreidia cyclops, Dicolpopollis kockeli, Compositoipollenites rhizophorus ssp. burghasungensis, Mediocolpopollis compactus ssp. ellenhausensis, Pentapollenites pentangulus, Subtriporopollenites simplex and Intratriporopollenites instructus. Palynological data indicate a humid subtropical climatic conditions during the deposition of the Cardak-Tokca sediments. Ecological analysis of the palynomorph assemblage identifies several paleo-associations of montana, lowland and slope, swamp and water-edge and freshwater aquatic elements. In this study, Cardak-Tokca, Cankiri-Corum, Thrace and southwest Anatolian molasse basins (Kale-Tavas and Denizli) were correlated in accordance with their palynostratigraphic content and the results show that the deposition took place during the Early Oligocene in the Cardak-Tokca basin. This basin is older than Thrace basin and southwest Anatolian molasse basins (Kale-Tavas and Denizli molasse) which were deposited during the Late Oligocene-Early Miocene.

  19. Implications of Spatial Variability in Heat Flow for Geothermal Resource Evaluation in Large Foreland Basins: The Case of the Western Canada Sedimentary Basin

    Directory of Open Access Journals (Sweden)

    Simon Weides

    2014-04-01

    Full Text Available Heat flow and geothermal gradient of the sedimentary succession of the Western Canada Sedimentary Basin (WCSB are mapped based on a large thermal database. Heat flow in the deep part of the basin varies from 30 mW/m2 in the south to high 100 mW/m2 in the north. As permeable strata are required for a successful geothermal application, the most important aquifers are discussed and evaluated. Regional temperature distribution within different aquifers is mapped for the first time, enabling a delineation of the most promising areas based on thermal field and aquifer properties. Results of previous regional studies on the geothermal potential of the WCSB are newly evaluated and discussed. In parts of the WCSB temperatures as high as 100–210 °C exist at depths of 3–5 km. Fluids from deep aquifers in these “hot” regions of the WCSB could be used in geothermal power plants to produce electricity. The geothermal resources of the shallower parts of the WCSB (>2 km could be used for warm water provision (>50 °C or district heating (>70 °C in urban areas.

  20. Moon, Mars, Mercury: Basin formation ages and implications for the maximum surface age and the migration of gaseous planets

    Science.gov (United States)

    Werner, Stephanie C.

    2014-08-01

    Basin formation ages for Moon, Mars and Mercury are determined by cratering statistics, compared and evaluated with respect to their maximum surface ages and available isotope ages, and two possible Solar System evolution models. Both Mars and Mercury appear to have undergone significant resurfacing, so that at least the first 200-400 million years are not recorded on their surfaces. Basin frequency and crater frequencies below 150 km indicate that the Moon has the oldest surface, Mercury has an intermediate age, and Mars has the youngest preserved terrain. An offset between the basin size-frequency distribution, the smaller crater size-frequency distribution and the main belt asteroid size-frequency distribution is observed in all three cases, suggesting an age difference of about 150 Ma between basin and smaller crater distribution-based ages. I interpreted this in terms of lack of understanding of the basin formation process, and suggest that one possible explanation for the apparently under-representative basin frequency could be a different (lower) average impact velocity compatible with the ‘Nice’ flux model. The basin formation pattern derived with the standard monotonically decaying or the sawtooth-like Nice-model flux does not reveal a coherent picture according to the late heavy bombardment idea. This is here attributed to an incomplete understanding of the cratering rate ratios between the planetary bodies considered here. Because of the Moon's unique formation history, I also suggest that it is questionable whether the Moon is a suitable analogue for the formation, evolution and cratering record of the other terrestrial bodies.

  1. Some postulates on the tecto magmatism, tectonostratigraphy and economic potential of kirana - malani basin: implications for occurrence of petroleum

    International Nuclear Information System (INIS)

    The so called shield elements exposed to the west of the Aravalli Orogen and exposed in Kirana, Nagar Parkar, Jodhpur, Malani, Tosham, Mount Abu and Erinpura are nether a part of Aravalli Orogen nor do they belong to the Vindhyan Basin. These volcano plutonic and sedimentary rocks represent a distinct cratonic rift assemblage. They were deposited in extensional basin formed as a result of rising of the mantle plume around 1000 ma. This basin is named by us as Malani-Kirana Basin. The stratigraphy of Kirana area has been revised and correlated with the Indian counterpart areas west of the Aravalli range. The Hachi volcanics are correlated with Tosham volcanics. The later are a part of an extensive volcano plutonic igneous province with other centres in Rajasthan and Nagar Parkar. The overlying sedimentary package of Kirana area is designated by us as Machh Super Group and it includes Tuguwali formation, Asian wala quartzites. Hadda quartzites and Sharaban conglomerates. The Machh Super Group is correlated with the lower part of the Marwar Supergroup. The equivalents of the upper Marwar Super group must occur in Pakistan to the south and south west of Kirana adjoining Bikaner - Nagaur Basin of India. Metamorphism in the Machh Super Group sediments must decrease in this direction, therefore hydrocarbon prospects may occur in Pakistani region adjoining hydrocarbon bearing Bikaner - Nagaur Basin of India. Volcanic hosted massive oxide-sulfide deposits have recently been discovered in the subsurface in Hachi volcanics near Chiniot. Such deposits must exist throughout Kirana-Malani Basin west of the Aravalli Orogen. (author)

  2. Clave fotográfica para hembras de Haemagogus Williston 1896 (Diptera: Culicidae) de Venezuela, con nuevo registro para el país / Pictorial key for females of Haemagogus Williston 1896 (Diptera: Culicidae) from Venezuela, with a new record for the country

    Scientific Electronic Library Online (English)

    Jonathan, Liria; Juan-Carlos, Navarro.

    2009-12-01

    Full Text Available El género neotropical Haemagogus Williston, está representado por mosquitos de actividad diurna, cuyas fases inmaduras se crían en fitotelmatas (huecos de árboles e internodos cortados de bambú). Especies de este género se han señalado involucradas en la transmisión de la Fiebre Amarilla selvática, [...] virus que circula en áreas boscosas de América Latina entre primates no humanos y marsupiales arborícolas por la picada de estos mosquitos. De las 28 especies reconocidas en el continente, 9 se encuentran en Venezuela. Una de ellas, Heamagogus (Conopostegus) clarki constituye un nuevo registro para el país. Se presenta una actualización de la taxonomía y de la distribución geográfica del género en Venezuela, así como la primera clave fotográfica con términos sencillos para el uso de personal no experimentado. Abstract in english The neotropical genus Heamagogus Williston includes mosquitoes with diurnal activity and immature breeding on Phytotelmata (tree-holes and cut bamboo internodes). Haemagogus species have been involved in sylvatic yellow fever transmission, a virus circulating in forest areas in Latin America among a [...] rboreal primates and marsupials by means of mosquito bite. The genus comprises 28 species, nine of them occurring in Venezuela. One of these, Haemagogus (Comopostegus) clarki, is a new record for this country. We show here an update of the taxonomic status and the geographical distribution of the genus in Venezuela and the first photographical key using simple terms for non-expert personnel.

  3. Surface geology of Williston 7.5-minute quadrangle, Aiken and Barnwell Counties, South Carolina

    International Nuclear Information System (INIS)

    Detailed geologic mapping has shown the distribution and lithologic character of stratigraphic units and sedimentary deposits in Williston quadrangle. A middle Eocene stratigraphic unit correlative with the restricted McBean Formation is the oldest unit at the surface. The McBean-equivalent unit occurs at low elevations along drainages in the north of the quadrangle but does not crop out. These beds are typically very fine- to fine-grained quartz sand, locally with abundant black organic matter and less commonly with calcium carbonate. The uppermost middle Eocene Orangeburg District bed, commonly composed of loose, clay-poor, very fine- to fine-grained quartz sand, occurs at the surface in the north and southwest of the quadrangle with sparse exposure. The upper Eocene Dry Branch Formation occurs on valley slopes throughout the quadrangle. The Dry Branch is composed of medium- to very coarse-grained quartz sand with varying amounts on interstitial clay and lesser bedded clay. The upper Eocene Tobacco road Sand occurs on upper valley slopes and some interfluves and consists of very fine-grained quartz sand to quartz granules. The upper Middle Miocene to lower Upper Miocene upland unit caps the interfluves and is dominantly coarse-grained quartz sand to quartz granules, with included granule-size particles of white clay that are weathered feldspars. Loose, incohesive quartzose sands of the eolian Pinehurst Formation, Upper Miocene to Lower Pliocene, occur on the eastern slopes of some interfluves in the north of the quadrangle. Quartz sand with varying included humic matter occurs in Carolina bays, and loose deposits of windblown sand occur on the rims of several Carolina bays. Quaternary alluvium fills the valley floors

  4. Surface geology of Williston 7. 5-minute quadrangle, Aiken and Barnwell Counties, South Carolina

    Energy Technology Data Exchange (ETDEWEB)

    Willoughby, R.H.; Nystrom, P.G. Jr. (South Carolina Geological Survey, Columbia, SC (United States)); Denham, M.E.; Eddy, C.A. (Westinghouse Savannah River Co., Aiken, SC (United States)); Price, L.K.

    1994-03-01

    Detailed geologic mapping has shown the distribution and lithologic character of stratigraphic units and sedimentary deposits in Williston quadrangle. A middle Eocene stratigraphic unit correlative with the restricted McBean Formation is the oldest unit at the surface. The McBean-equivalent unit occurs at low elevations along drainages in the north of the quadrangle but does not crop out. These beds are typically very fine- to fine-grained quartz sand, locally with abundant black organic matter and less commonly with calcium carbonate. The uppermost middle Eocene Orangeburg District bed, commonly composed of loose, clay-poor, very fine- to fine-grained quartz sand, occurs at the surface in the north and southwest of the quadrangle with sparse exposure. The upper Eocene Dry Branch Formation occurs on valley slopes throughout the quadrangle. The Dry Branch is composed of medium- to very coarse-grained quartz sand with varying amounts on interstitial clay and lesser bedded clay. The upper Eocene Tobacco road Sand occurs on upper valley slopes and some interfluves and consists of very fine-grained quartz sand to quartz granules. The upper Middle Miocene to lower Upper Miocene upland unit caps the interfluves and is dominantly coarse-grained quartz sand to quartz granules, with included granule-size particles of white clay that are weathered feldspars. Loose, incohesive quartzose sands of the eolian Pinehurst Formation, Upper Miocene to Lower Pliocene, occur on the eastern slopes of some interfluves in the north of the quadrangle. Quartz sand with varying included humic matter occurs in Carolina bays, and loose deposits of windblown sand occur on the rims of several Carolina bays. Quaternary alluvium fills the valley floors.

  5. Oceanic response to Pliensbachian and Toarcian magmatic events: Implications from an organic-rich basinal succession in the NW Tethys

    Science.gov (United States)

    Neumeister, S.; Gratzer, R.; Algeo, T. J.; Bechtel, A.; Gawlick, H.-J.; Newton, R. J.; Sachsenhofer, R. F.

    2015-03-01

    The Bächental bituminous marls (Bächentaler Bitumenmergel) belonging to the Sachrang Member of the Lower Jurassic Middle Allgäu Formation were investigated using a multidisciplinary approach to determine environmental controls on the formation of organic-rich deposits in a semi-restricted basin of the NW Tethys during the Early Jurassic. The marls are subdivided into three units on the basis of mineralogical composition, source-rock parameters, redox conditions, salinity variations, and diagenetic processes. Redox proxies (e.g., pristane/phytane ratio; aryl isoprenoids; bioturbation; ternary plot of iron, total organic carbon, and sulphur) indicate varying suboxic to euxinic conditions during deposition of the Bächental section. Redox variations were mainly controlled by sea-level fluctuations with the tectonically complex bathymetry of the Bächental basin determining watermass exchange with the Tethys Ocean. Accordingly, strongest anoxia and highest total organic carbon content (up to 13%) occur in the middle part of the profile (upper tenuicostatum and lower falciferum zones), coincident with an increase in surface-water productivity during a period of relative sea-level lowstand that induced salinity stratification in a stagnant basin setting. This level corresponds to the time interval of the lower Toarcian oceanic anoxic event (T-OAE). However, the absence of the widely observed lower Toarcian negative carbon isotope excursion in the study section questions its unrestricted use as a global chemostratigraphic marker. Stratigraphic correlation of the thermally immature Bächental bituminous marls with the Posidonia Shale of SW Germany on the basis of C27/C29 sterane ratio profiles and ammonite data suggests that deposition of organic matter-rich sediments in isolated basins in the Alpine realm commenced earlier (late Pliensbachian margaritatus Zone) than in regionally proximal epicontinental seas (early Toarcian tenuicostatum Zone). The late Pliensbachian onset of reducing conditions in the Bächental basin coincided with an influx of volcaniclastic detritus that was possibly connected to complex rifting processes of the Alpine Tethys and with a globally observed eruption-induced extinction event. The level of maximum organic matter accumulation in the Bächental basin corresponds to the main eruptive phase of the Karoo-Ferrar large igneous province (LIP), confirming its massive impact on global climate and oceanic conditions during the Early Jurassic. The Bächental marl succession is thus a record of the complex interaction of global (i.e., LIP) and local (e.g., redox and salinity variations, basin morphology) factors that caused reducing conditions and organic matter enrichment in the Bächental basin. These developments resulted in highly inhomogeneous environmental conditions in semi-restricted basins of the NW Tethyan domain during late Pliensbachian and early Toarcian time.

  6. Tectonic Evolution of Tarim Basin in Cambrian-Ordovician and the Implication for Reservoir Development, NW China

    Science.gov (United States)

    Yinglu, Pan; Bingsong, Yu

    2015-04-01

    In order to search after the control of regional tectonic evolution of Tarim basin on the inside distribution of sedimentary facies and reservoir development, this paper, based on the research of plate-tectonic evolution of Tarim basin, conducts an in-depth analysis on the basin's inside sedimentary response to the Eopaleozoic regional geodynamic reversion from extension to convergence around Tarim plate, and concludes that the regional geodynamic environment of surrounding areas closely contributes to the formation and evolution of paleo-uplifts, differentiation of sedimentary facies in platform, distribution of high-energy reef and bank facies belts, conversion of sedimentary base level from fall to rise, obvious change of lithology from dolomite to limestone, and formation of several unconformity surfaces in Ordovician System in the basin. A series of sedimentary responses in the basin are controlled by the regional dynamic setting, which not only controls the distribution of reservoirs in reef and bank facies but also restricts the development and distribution of karst reservoirs controlled by the unconformity surfaces. This offers the macro geological evidences for us to further analyze and evaluate the distribution of favorable reservoirs.

  7. Late Permian to Late Triassic basin evolution of North Vietnam: geodynamic implications for the South China and Indochina blocks

    Science.gov (United States)

    Rossignol, Camille; Bourquin, Sylvie; Hallot, Erwan; Poujol, Marc; Roger, Françoise

    2015-04-01

    The core of South East Asia is composed of a mosaic of continental blocks, among which the Indochina and the South China blocks (present day northern Vietnam), amalgamated during the Permian and/or the Triassic. Late Permian to Late Triassic geodynamic evolution of these two blocks remains controversial. The main discussion points concern the existence and the closure of an oceanic domain separating the Indochina and the South China blocks during this period. Especially, the polarity and the timing of the subduction zone that led to the collision between the blocks as well as the present location of the suture delimiting them are a matter of debate. Despite the valuable information they can provide, the sedimentary basins from northern Vietnam have been neglected in the previous studies dealing with the geodynamic evolution of South East Asia. To determine the geodynamic evolution of the area, the basins of Sam Nua and Song Da, presently located in North Vietnam, have been investigated using a combined approach involving sedimentology, geochronology (U-Pb/zircon) and geochemistry (whole-rock major and trace elements composition of both volcanic and volcaniclastic rocks). The palaeoenvironment evolution, the main unconformities, their age and the tectonic affinities of the interbedded volcanic and volcaniclastics series have been characterized for these two basins. Our results demonstrate (i) that the Song Da Basin exhibits a palaeogeographic affinity with the South China block, (ii) the occurrence of extensive calk-alkaline volcanism and associated volcaniclastic deposits in the Sam Nua Basin, related to the existence of an active magmatic arc during the Early and the lower Middle Triassic, (iii) a South dipping (present day coordinate) oceanic lithosphere beneath the Indochina block, deduced from the location of the magmatic arc south of the potential suture zones, (iv) that an angular unconformity postdates the lower Middle Triassic volcaniclastic deposits in the Sam Nua basin. This unconformity, crosscutting the subduction related deposits, is interpreted as the result of the collision between the Indochina and the South China blocks.

  8. Anomalous crustal and lithospheric mantle structure of southern part of the Vindhyan Basin and its geodynamic implications

    Science.gov (United States)

    Pandey, O. P.; Srivastava, R. P.; Vedanti, N.; Dutta, S.; Dimri, V. P.

    2014-09-01

    Tectonically active Vindhyan intracratonic basin situated in central India, forms one of the largest Proterozoic sedimentary basins of the world. Possibility of hydrocarbon occurrences in thick sediments of the southern part of this basin, has led to surge in geological and geophysical investigations by various agencies. An attempt to synthesize such multiparametric data in an integrated manner, has provided a new understanding to the prevailing crustal configuration, thermal regime and nature of its geodynamic evolution. Apparently, this region has been subjected to sustained uplift, erosion and magmatism followed by crustal extension, rifting and subsidence due to episodic thermal interaction of the crust with the hot underlying mantle. Almost 5-6 km thick sedimentation took place in the deep faulted Jabera Basin, either directly over the Bijawar/Mahakoshal group of mafic rocks or high velocity-high density exhumed middle part of the crust. Detailed gravity observations indicate further extension of the basin probably beyond NSL rift in the south. A high heat flow of about 78 mW/m2 has also been estimated for this basin, which is characterized by extremely high Moho temperatures (exceeding 1000 °C) and mantle heat flow (56 mW/m2) besides a very thin lithospheric lid of only about 50 km. Many areas of this terrain are thickly underplated by infused magmas and from some segments, granitic-gneissic upper crust has either been completely eroded or now only a thin veneer of such rocks exists due to sustained exhumation of deep seated rocks. A 5-8 km thick retrogressed metasomatized zone, with significantly reduced velocities, has also been identified around mid to lower crustal transition.

  9. Multi-Model CIMP5 projected impacts of increased greenhouse gases on the Niger basin and implications for hydropower production

    Science.gov (United States)

    Oyerinde, Ganiyu; Wisser, Dominik

    2014-05-01

    Climate change could potentially have large impacts on water availability in West Africa and the predictions are accrued with high uncertainties in this region. Countries in the Niger River basin (West Africa) plan the investment of 200 million in the installation of an additional 400MW of hydropower in the nearest future, adding to the existing 685MW. With the impacts of climate change in the basin already occurring, there is a need for comprehending the influence of future hydro-climatic changes on water resources and hydro-power generation in the basin. This study uses a hydrological model to simulate river flow under present and future conditions and evaluates the impacts of potential changes on electricity production of the largest hydroelectric dam (Kainji) in the Niger Basin. The Kainji reservoir produces 25 per cent of the current energy needs of Nigeria and was subject to large fluctuations in energy production as a result of variable inflow and operational reasons. Inflow into the reservoir was simulated using hydroclimatic data from a set of 7 regional climate models (RCM) with two emission scenarios from the CORDEX-Africa regional downscaling experiment, driven with CMIP5 data. Based on observations of inflow, water level in the reservoir, and energy production we developed a simple hydroelectricity production model to simulate future energy production for the reservoir. Results suggest increases in river flow for the majority of RCM data as a result of increases in precipitation in the headwaters of the basin around 2050 and slightly decreasing trends for low emission scenarios by the end of the century. Despite this consistent increase, shifts in timing of river flow can challenge the reliable production of energy. This analysis could help assess the planning of hydropower schemes in the basin for a sustainable production of hydroelectricity in the future.

  10. Distinguishing aeolian signature from lacustrine sediments of the Qaidam Basin in northeastern Qinghai-Tibetan Plateau and its palaeoclimatic implications

    Science.gov (United States)

    An, FuYuan; Ma, HaiZhou; Wei, HaiCheng; Lai, ZhongPing

    2012-06-01

    Qarhan playa is located in the eastern-central Qaidam Basin in the northeastern Qinghai-Tibetan Plateau. As a lake-depocenter since the Pleistocene and surrounded by Gobi and yardang fields, it might have deposited abundant aeolian materials. Distinguishing its aeolian signature from lacustrine sediments is important for understanding the landform processes and environmental changes, which is the focus of the current study. Based on major-elements analysis, microtextures of quartz grains, and features of grain-size frequency curves and other grain-size parameters, we demonstrate the existence of aeolian component in the lacustrine sequences of a 102 m core (ISL1A). Grain-size distribution curve statistics on 60 samples from two extreme palaeoclimate environments (hyperarid and humid), as well as multi-proxies records comparison, indicate that the mode at about 40 ?m represents the aeolian component and the 10-70 ?m fraction of grain-size is a valid proxy of East Asian winter monsoon, and that the 70-650 ?m fraction represents the intensity of dust storms. The erosive lacustrine sediments in the western Qaidam Basin and the alluvial/fluvial fans in nearby piedmont are probably important sources for these aeolian materials. The similarities of major-element data for samples from the Qaidam Basin (both lacustrine and loess), Qinghai Lake (loess), and the Chinese Loess Plateau (loess) indicate that the Qaidam Basin is a dust source for the loess in Qinghai Lake and the Chinese Loess Plateau.

  11. Cenozoic evolution of the Pamir plateau recorded in surrounding basins, implications on Asian climate and land-sea distribution

    Science.gov (United States)

    Dupont-Nivet, Guillaume; Yang, Wei; Blayney, Tamsin; Proust, Jean-Noel; Guo, Zhaojie; Grothe, Arjen; Mandic, Oleg; Fionori, Chiara; Bougeois, Laurie; Najman, Yanina

    2015-04-01

    The Cenozoic Pamir orogen formed in response to the India-Asia collision. Existing datasets shows that the range grew since ca. 25 Ma, however the early Cenozoic history remains particularly enigmatic. In that peculiar period, global climate changed from greenhouse to icehouse, the proto-Paratethys sea retreated out of Asia and continental aridification as well as monsoons established over Asia. These environmental changes are held responsible for major floral and faunal crises including the emergence of plant communities and the dispersion of key mammal groups from Asia onto other continents. However, the causal relationships between these events remains to be established because of the lack of accurate age constraints on their geological records. Here, we provide well-dated stratigraphic records using magneto- and bio-stratigraphy from the basins surrounding the Pamir. Southeast of the Pamir, along the Kunlun Shan into the southwestern Tarim Basin, Eocene marine deposits are continuously overlain by 41 to 15 Ma continental redbeds themselves overlain by conglomerates in a classic foreland sequence with upward increasing grain-size, accumulation rates and provenance proximity. However, North of the Pamir along the southwestern Tian Shan and West of the Pamir into the Afghan-Tadjik Basin, the entire Oligocene period appears to be missing from the record between the last marine and the first continental sediments dated to the Early Miocene. This supports a simple basin evolution model in response to initial Pamir indentation with Eocene foreland basin activation in the Southeast related to the Kunlun Shan northward thrusting, followed much later by early Miocene activation of the northern foreland basin related to the southwestern Tian Shan overthrusting. The coeval activation of a lithospheric right-lateral strike-slip system along the Pamir/Tarim boundary may have enabled to transfer deformation from the India-Asia collision zone to the Tian Shan and possibly the Talas Fergana fault. This simple model suggests the following two-stage paleoenvironmental evolution: (1) Late Eocene sea retreat linked to the onset of Pamir indentation in conjunction with global sea-level drop, decreasing CO2 levels and ice-cap formation and (2) Early Miocene closure of the Tarim Basin by northward indentation of the Pamir plateau. This two stage evolution is consistent with the Eocene occurrence of continental aridity and Asian Monsoons and their Early Miocene intensification.

  12. Diet and environment of a mid-Pliocene fauna in the Zanda Basin (western Himalaya): Paleo-elevation implications

    Science.gov (United States)

    Wang, Y.; Xu, Y.; Khawaja, S. N.; Wang, X.; Passey, B. H.; Zhang, C.; Li, Q.; Tseng, Z. J.; Takeuchi, G.; Deng, T.; Xie, G.

    2011-12-01

    A mid-Pliocene fauna (3.1-4.0 Ma) was recently discovered in the Zanda Basin in western Himalaya, at an elevation of about 4200 m above sea level. These fossil materials provide a unique window for examining the linkage among tectonic, climatic and biotic changes. Here we report the initial results from isotopic analyses of this fauna and of modern herbivores in the Zanda Basin. The ?13C values of enamel samples from modern wild Tibetan ass, horse, cow and goat from the Zanda Basin are -9.1±2.1%, which indicate a diet comprising predominantly of C3 plants and are consistent with the current dominance of C3 vegetation in the area. The enamel-?13C values of the fossil horse, rhino, deer, and bovid are -9.6±0.8%, indicating that these ancient mammals, like modern herbivores in the area, fed primarily on C3 vegetation and lived in an environment dominated by C3 plants. The enamel-?18O values of mid-Pliocene obligate drinkers (i.e., horse and rhino) are lower than those of their modern counterpart, most likely indicating a shift in climate to much drier conditions after ~3-4 Ma. Preliminary paleo-temperature estimates derived from a fossil-based temperature proxy as well as the "clumped isotope" thermometer for the mid-Pliocene Zanda Basin, although somewhat equivocal, are close to the present-day mean annual temperature in the area, suggesting that the paleo-elevation of the Zanda Basin in the mid-Pliocene was similar to its present-day elevation.

  13. Quality and age of shallow groundwater in the Bakken Formation production area, Williston Basin, Montana and North Dakota

    Science.gov (United States)

    McMahon, Peter B.; Caldwell, Rodney R.; Galloway, Joel M.; Valder, Joshua F.; Hunt, Andrew G.

    2015-01-01

    The quality and age of shallow groundwater in the Bakken Formation production area were characterized using data from 30 randomly distributed domestic wells screened in the upper Fort Union Formation. Comparison of inorganic and organic chemical concentrations to health based drinking-water standards, correlation analysis of concentrations with oil and gas well locations, and isotopic data give no indication that energy-development activities affected groundwater quality. It is important, however, to consider these results in the context of groundwater age. Most samples were recharged before the early 1950s and had 14C ages ranging from 30,000?years. Thus, domestic wells may not be as well suited for detecting contamination associated with recent surface spills as shallower wells screened near the water table. Old groundwater could be contaminated directly by recent subsurface leaks from imperfectly cemented oil and gas wells, but horizontal groundwater velocities calculated from 14C ages imply that the contaminants would still be less than 0.5?km from their source. For the wells sampled in this study, the median distance to the nearest oil and gas well was 4.6?km. Because of the slow velocities, a long-term commitment to groundwater monitoring in the upper Fort Union Formation is needed to assess the effects of energy development on groundwater quality. In conjunction with that effort, monitoring could be done closer to energy-development activities to increase the likelihood of early detection of groundwater contamination if it did occur.

  14. Clay mineralogical studies on Bijawars of the Sonrai Basin: palaeoenvironmental implications and inferences on the uranium mineralization

    International Nuclear Information System (INIS)

    Clays associated with the Precambrian unconformity-related (sensu lato) uranium mineralization that occur along fractures of Rohini carbonate, Bandai sandstone and clay-organic rich black carbonaceous Gorakalan shale of the Sonrai Formation from Bijawar Group is significant. Nature and structural complexity of these clays have been studied to understand depositional mechanism and palaeoenvironmental conditions responsible for the restricted enrichment of uranium in the Sonrai basin. Clays ( chlorite> illite > smectite mineral assemblages, whereas, Solda Formation contains kaolinite > illite > chlorite clays. It has been found that the former mineral assemblage resulted from the alteration process is associated with the uranium mineralization and follow progressive reaction series, indicating palaeoenvironmental (cycles of tropical humid to semi-arid/arid) changes prevailed during maturation of the Sonrai basin. The hydrothermal activity possibly associated with Kurrat volcanics is accountable for the clay mineral alterations

  15. Hydrologic impacts of climate change on the Nile River basin: Implications of the 2007 IPCC climate scenarios

    OpenAIRE

    Beyene, T.; D. P. Lettenmaier; Kabat, P.

    2010-01-01

    We assess the potential impacts of climate change on the hydrology and water resources of the Nile River basin using a macroscale hydrology model. Model inputs are bias corrected and spatially downscaled 21st Century simulations from 11 General Circulation Models (GCMs) and two global emissions scenarios (A2 and B1) archived from the 2007 IPCC Fourth Assessment Report (AR4). While all GCMs agree with respect to the direction of 21st Century temperature changes, there is considerable variabili...

  16. A regional ocean circulation model for the mid-Cretaceous North Atlantic Basin: implications for black shale formation

    OpenAIRE

    R. P. M. Topper; J. Trabucho Alexandre; Tuenter, E.; P. Th. Meijer

    2010-01-01

    High concentrations of organic matter accumulated in marine sediments during Oceanic Anoxic Events (OAEs) in the Cretaceous. Model studies examining these events invariably make use of global ocean circulation models. In this study, a regional model for the North Atlantic Basin during OAE2 at the Cenomanian-Turonian boundary is developed. A first order check of the results is performed by comparison with the results of a recent global Cenomanian CCSM3 run from which boundary and initial condi...

  17. Mechanical stratification of autochthonous salt: Implications from basin-scale numerical models of rifted margin salt tectonics

    Science.gov (United States)

    Ings, Steven; Albertz, Markus

    2014-05-01

    Deformation of salt and sediments owing to the flow of weak evaporites is a common phenomenon in sedimentary basins worldwide, and the resulting structures and thermal regimes have a significant impact on hydrocarbon exploration. Evaporite sequences ('salt') of significant thickness (e.g., >1km) are typically deposited in many cycles of seawater inundation and evaporation in restricted basins resulting in layered autochthonous evaporite packages. However, analogue and numerical models of salt tectonics typically treat salt as a homogeneous viscous material, often with properties of halite, the weakest evaporite. In this study, we present results of two-dimensional plane-strain numerical experiments designed to illustrate the effects of variable evaporite viscosity and embedded frictional-plastic ('brittle') sediment layers on the style of salt flow and associated deformation of the sedimentary overburden. Evaporite viscosity is a first-order control on salt flow rate and the style of overburden deformation. Near-complete evacuation of low-viscosity salt occurs beneath expulsion basins, whereas significant salt is trapped when viscosity is high. Embedded frictional-plastic sediment layers (with finite yield strength) partition salt flow and develop transient contractional structures (folds, thrust faults, and folded faults) in a seaward salt-squeeze flow regime. Multiple internal sediment layers reduce the overall seaward salt flow during sediment aggradation, leaving more salt behind to be re-mobilized during subsequent progradation. This produces more seaward extensive allochthonous salt sheets. If there is a density difference between the embedded layers and the surrounding salt, then the embedded layers 'fractionate' during deformation and either float to the surface or sink to the bottom (depending on density), creating a thick zone of pure halite. Such a process of 'buoyancy fractionation' may partially explain the apparent paradox of layered salt in autochthonous salt basins and thick packages of pure halite in allochthonous salt sheets.

  18. Single-grain detrital-muscovite ages from Lower Cretaceous sandstones, Scotian Basin, and their implications for provenance

    Energy Technology Data Exchange (ETDEWEB)

    Reynolds, P.H.; Grist, A.M. [Dalhousie Univ., Halifax, NS (Canada). Dept. of Earth Sciences; Pe-Piper, G. [Saint Mary' s Univ., Halifax, NS (Canada). Dept. of Geology; Piper, D.J.W. [Geological Survey of Canada, Bedford Inst. of Oceanography, Dartmouth, NS (Canada). Atlantic Geoscience Center

    2009-03-15

    Detrital muscovite is relatively abundant in the Lower Cretaceous rocks of the Scotian Basin, where the deltaic sandstones form important gas reservoirs. This paper reported on a study that used the single-grain geochronology dating technique to re-examine the significance of muscovite as a detrital mineral in the Scotian Basin. The objective was to better understand the sources of sediments in the offshore reservoir sandstone and to identify sediment dispersal patterns. Information on the detrital petrology and sediment provenance of the Lower Cretaceous sandstone is important for exploration models and for determining diagenesis and reservoir quality. One hundred muscovite grains were dated from a transect of wells near Sable Island. An additional 17 grains were dated from the Naskapi N-30 well in the western part of the basin. In general, the muscovite ranges in age from ca. 420 to 240 Ma, suggesting that ages were not reset by post-depositional alteration. The principal sources were rocks that had experienced resetting during Alleghenian deformation and Late Triassic, earliest Jurassic rifting. According to the distribution of ages and mass balance calculations, the sources were primarily Meguma metasedimentary rocks on the inner Scotian Shelf. The age distribution at Naskapi N-30 is similar to that in the South Mountain batholith, except for some grains younger than 360 Ma that suggest an offshore source with Alleghenian resetting. This paper also provided evidence that the inner shelf was an erosional area during the Early Cretaceous. 59 refs., 2 tabs., 7 figs., 1 appendix.

  19. Genetic structure and historical diversification of catfish Brachyplatystoma platynemum (Siluriformes: Pimelodidae) in the Amazon basin with implications for its conservation.

    Science.gov (United States)

    Ochoa, Luz Eneida; Pereira, Luiz Henrique G; Costa-Silva, Guilherme Jose; Roxo, Fábio F; Batista, Jacqueline S; Formiga, Kyara; Foresti, Fausto; Oliveira, Claudio

    2015-05-01

    Brachyplatystoma platynemum is a catfish species widely distributed in the Amazon basin. Despite being considered of little commercial interest, the decline in other fish populations has contributed to the increase in the catches of this species. The structure, population genetic variability, and evolutionary process that have driven the diversification of this species are presently unknown. Considering that, in order to better understand the genetic structure of this species, we analyzed individuals from seven locations of the Amazon basin using eight molecular markers: control region and cytochrome b mtDNA sequences, and a set of six nuclear microsatellite loci. The results show high levels of haplotype diversity and point to the occurrence of two structured populations (Amazon River and the Madeira River) with high values for F ST. Divergence time estimates based on mtDNA indicated that these populations diverged about 1.0 Mya (0.2-2.5 Mya 95% HPD) using cytochrome b and 1.4 Mya (0.2-2.7 Mya 95% HPD) using control region. During that time, the influence of climate changes and hydrological events such as sea level oscillations and drainage isolation as a result of geological processes in the Pleistocene may have contributed to the current structure of B. platynemum populations, as well as of differences in water chemistry in Madeira River. The strong genetic structure and the time of genetic divergence estimated for the groups may indicate the existence of strong structure populations of B. platynemum in the Amazon basin. PMID:26045952

  20. Sedimentary budgets of the Tanzania coastal basin and implications for uplift history of the East African rift system

    Science.gov (United States)

    Said, Aymen; Moder, Christoph; Clark, Stuart; Abdelmalak, Mohamed Mansour

    2015-11-01

    Data from 23 wells were used to quantify the sedimentary budgets in the Tanzania coastal basin in order to unravel the uplift chronology of the sourcing area located in the East African Rift System. We quantified the siliciclastic sedimentary volumes preserved in the Tanzania coastal basin corrected for compaction and in situ (e.g., carbonates) production. We found that the drainage areas, which supplied sediments to this basin, were eroded in four episodes: (1) during the middle Jurassic, (2) during the Campanian-Palaeocene, (3) during the middle Eocene and (4) during the Miocene. Three of these high erosion and sedimentation periods are more likely related to uplift events in the East African Rift System and earlier rift shoulders and plume uplifts. Indeed, rapid cooling in the rift system and high denudation rates in the sediment source area are coeval with these recorded pulses. However, the middle Eocene pulse was synchronous with a fall in the sea level, a climatic change and slow cooling of the rift flanks and thus seems more likely due to climatic and eustatic variations. We show that the rift shoulders of the East African rift system have inherited their present relief from at least three epeirogenic uplift pulses of middle Jurassic, Campanian-Palaeocene, and Miocene ages.

  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. Magnetostratigraphy of deep drilling core SG-1 in the western Qaidam Basin (NE Tibetan Plateau) and its tectonic implications

    Science.gov (United States)

    Zhang, Weilin; Appel, Erwin; Fang, Xiaomin; Song, Chunhui; Cirpka, Olaf

    2012-07-01

    The Qaidam Basin is the largest intermontane basin of the northeastern Tibetan Plateau and contains a continuous Cenozoic sequence of lacustrine sediments. A ~ 1000-m-deep drilling (SG-1) with an average core recovery of ~ 95% was carried out in the depocenter of the Chahansilatu playa (sub-depression) in the western Qaidam Basin, aimed to obtain a high-resolution record of the paleoenvironmental evolution and the erosion history. Stepwise alternating field and thermal demagnetization, together with rock magnetic results, revealed a stable remanent magnetization for most samples, carried by magnetite. The polarity sequence consisted of 16 normal and 15 reverse zones which can be correlated with chrons 1n to 2An of the global geomagnetic polarity time scale. Magnetostratigraphic results date the entire core SG-1 at ~ 2.77 Ma to ~ 0.1 Ma and yielded sediment accumulation rate (SAR) ranging from 26.1 cm/ka to 51.5 cm/ka. Maximum SARs occurred within the intervals of ~ 2.6-2.2 Ma and after ~ 0.8 Ma, indicating two episodes of erosion, which we relate to pulse tectonic uplift of the NE Tibetan Plateau with subsequent global cooling.

  3. Contrasting distributions of groundwater arsenic and uranium in the western Hetao basin, Inner Mongolia: Implication for origins and fate controls.

    Science.gov (United States)

    Guo, Huaming; Jia, Yongfeng; Wanty, Richard B; Jiang, Yuxiao; Zhao, Weiguang; Xiu, Wei; Shen, Jiaxing; Li, Yuan; Cao, Yongsheng; Wu, Yang; Zhang, Di; Wei, Chao; Zhang, Yilong; Cao, Wengeng; Foster, Andrea

    2016-01-15

    Although As concentrations have been investigated in shallow groundwater from the Hetao basin, China, less is known about U and As distributions in deep groundwater, which would help to better understand their origins and fate controls. Two hundred and ninety-nine groundwater samples, 122 sediment samples, and 14 rock samples were taken from the northwest portion of the Hetao basin, and analyzed for geochemical parameters. Results showed contrasting distributions of groundwater U and As, with high U and low As concentrations in the alluvial fans along the basin margins, and low U and high As concentrations downgradient in the flat plain. The probable sources of both As and U in groundwater were ultimately traced to the bedrocks in the local mountains (the Langshan Mountains). Chemical weathering of U-bearing rocks (schist, phyllite, and carbonate veins) released and mobilized U as UO2(CO3)2(2-) and UO2(CO3)3(4-) species in the alluvial fans under oxic conditions and suboxic conditions where reductions of Mn and NO3(-) were favorable (OSO), resulting in high groundwater U concentrations. Conversely, the recent weathering of As-bearing rocks (schist, phyllite, and sulfides) led to the formation of As-bearing Fe(III) (hydr)oxides in sediments, resulting in low groundwater As concentrations. Arsenic mobilization and U immobilization occurred in suboxic conditions where reduction of Fe(III) oxides was favorable and reducing conditions (SOR). Reduction of As-bearing Fe(III) (hydr)oxides, which were formed during palaeo-weathering and transported and deposited as Quaternary aquifer sediments, was believed to release As into groundwater. Reduction of U(VI) to U(IV) would lead to the formation of uraninite, and therefore remove U from groundwater. We conclude that the contrasting distributions of groundwater As and U present a challenge to ensuring safe drinking water in analogous areas, especially with high background values of U and As. PMID:26473717

  4. Evidence of lacustrine sedimentation in the Upper Permian Bijori Formation, Satpura Gondwana basin: Palaeogeographic and tectonic implications

    Indian Academy of Sciences (India)

    Tapan Chakraborty; Soumen Sarkar

    2005-06-01

    The Upper Permian Bijori Formation of the Satpura Gondwana basin comprising fine- to coarsegrained sandstone, carbonaceous shale/mudstone and thin coal bands was previously interpreted as the deposits of meandering rivers. The present study documents abundance of wave ripples, hummocky and swaley cross-stratification and combined flow bedforms in the Bijori Formation, suggesting that a significant part of the formation was deposited in a wave-agitated environment. Evidence of near-emergent depositional conditions provided by repeated occurrence of rootlet beds and hydromorphic paleosols, local flooding surfaces denoting rapid fluctuation of water level, occurrences of temnospondyl vertebrate fossils, and absence of tidal signatures and marine fossils suggest a lacustrine rather than marine depositional regime. Five facies associations recognised within the Bijori Formation are inferred to represent fluvial channels and associated floodplains (FA1), lake shorelines (FA2), subaqueous distributary channels and associated levees (FA3), wave- and storm-affected delta front (FA4), and open lacustrine/lower shoreface (FA5) deposits. The planoconcave fluvial channel-fill sandbodies with unidirectional cross-beds are clearly distinguishable from the delta front bars that show a convexo-plan or bi-convex sandbody geometry and dominance of wave and combined flow bedforms. Some of the distributary channels record interaction of fluvial and wave-dominated basinal processes. Major distributary sandbodies show a north to northwest flow direction while wave-affected delta front sandbodies show very complex flow patterns reflecting interaction between fluvial discharge and wave processes. Wave ripple crest trends show that the lake shoreline had an overall east–northeast to west–southwest orientation. The lack of documented contemporaneous lacustrine or marine sediments in the Satpura Gondwana basin posed a major problem of basin-scale palaeogeographic reconstruction. The existence of Bijori lake solves the problem and the lake is inferred to have acted as repository for the contemporaneous alluvial drainage. Development of the large Bijori lake body implies generation of accommodation space exceeding the rate of sediment supplied and thus represents locus of high tectonic subsidence. Transition of fluvial sediments with red mudstone and calcareous soil profile in the lower part of the succession to carbonaceous shale and coal-bearing lacustrine sediments in the upper part, denote a change from a warm semi-arid climate with seasonal rainfall to a more humid one.

  5. A regional ocean circulation model for the mid-Cretaceous North Atlantic Basin: implications for black shale formation

    Directory of Open Access Journals (Sweden)

    R. P. M. Topper

    2011-03-01

    Full Text Available High concentrations of organic matter accumulated in marine sediments during Oceanic Anoxic Events (OAEs in the Cretaceous. Model studies examining these events invariably make use of global ocean circulation models. In this study, a regional model for the North Atlantic Basin during OAE2 at the Cenomanian-Turonian boundary has been developed. A first order check of the results has been performed by comparison with the results of a recent global Cenomanian CCSM3 run, from which boundary and initial conditions were obtained. The regional model is able to maintain tracer patterns and to produce velocity patterns similar to the global model. The sensitivity of the basin tracer and circulation patterns to changes in the geometry of the connections with the global ocean is examined with three experiments with different bathymetries near the sponges. Different geometries turn out to have little effect on tracer distribution, but do affect circulation and upwelling patterns. The regional model is also used to test the hypothesis that ocean circulation may have been behind the deposition of black shales during OAEs. Three scenarios are tested which are thought to represent pre-OAE, OAE and post-OAE situations. Model results confirm that Pacific intermediate inflow together with coastal upwelling could have enhanced primary production during OAE2. A low sea level in the pre-OAE scenario could have inhibited large scale black shale formation, as could have the opening of the Equatorial Atlantic Seaway in the post-OAE scenario.

  6. Fish communities of the Sacramento River Basin: Implications for conservation of native fishes in the Central Valley, California

    Science.gov (United States)

    May, J.T.; Brown, L.R.

    2002-01-01

    The associations of resident fish communities with environmental variables and stream condition were evaluated at representative sites within the Sacramento River Basin, California between 1996 and 1998 using multivariate ordination techniques and by calculating six fish community metrics. In addition, the results of the current study were compared with recent studies in the San Joaquin River drainage to provide a wider perspective of the condition of resident fish communities in the Central Valley of California as a whole. Within the Sacramento drainage, species distributions were correlated with elevational and substrate size gradients; however, the elevation of a sampling site was correlated with a suite of water-quality and habitat variables that are indicative of land use effects on physiochemical stream parameters. Four fish community metrics - percentage of native fish, percentage of intolerant fish, number of tolerant species, and percentage of fish with external anomalies - were responsive to environmental quality. Comparisons between the current study and recent studies in the San Joaquin River drainage suggested that differences in water-management practices may have significant effects on native species fish community structure. Additionally, the results of the current study suggest that index of biotic integrity-type indices can be developed for the Sacramento River Basin and possibly the entire Central Valley, California. The protection of native fish communities in the Central Valley and other arid environments continues to be a conflict between human needs for water resources and the requirements of aquatic ecosystems; preservation of these ecosystems will require innovative management strategies.

  7. Risk of water scarcity and water policy implications for crop production in the Ebro basin in Spain

    OpenAIRE

    S Quiroga; Z. Fernández-Haddad; Iglesias, A

    2010-01-01

    The increasing pressure on water systems in the Mediterranean enhances existing water conflicts and threatens water supply for agriculture. In this context, one of the main priorities for agricultural research and public policy is the adaptation of crop yields to water pressures. This paper focuses on the evaluation of hydrological risk and water policy implications for food production. Our methodological approach includes four steps. For the first step, we estimate the impacts of rain...

  8. Messinian events in the Sorbas Basin in southeastern Spain and their implications in the recent history of the Mediterranean

    Science.gov (United States)

    Martín, JoséM.; Braga, Juan C.

    1994-05-01

    The Messinian (Late Miocene) marine stratigraphic record of the Sorbas Basin (S.E. Spain) is well preserved and can be considered as being representative of the entire western Mediterranean. It exhibits a series of features relating to: (1) the composition, characteristics and evolution of coral reefs; (2) changes between temperate and subtropical climates; and (3) the extensive development of microbial carbonates (stromatolites and thrombolites) at the end of the Messinian. Each of these features has global significance. Porites, which is the major and almost only coral component in reefs, is heavily encrusted with stromatolites. These reefs grew at the edge of the subtropical belt and were totally eliminated at the end of the Messinian because of global cooling. Lowermost-Messinian carbonate sediments in the Sorbas Basin reflect a temperate climate, whereas those immediately above, which contain bioherms and coastal reefs, are subtropical. The shift from temperate to subtropical conditions during the early Messinian was accompanied by an important change in water circulation within the western Mediterranean. Temperate times were marked by cold surface Atlantic waters entering the Mediterranean, whereas subtropical times coincided with warm surface waters entering the western Mediterranean from the east. The subtropical waters were thermally stratified, which favoured the deposition of euxinic marls and diatomites at the centre of the basin. The upwelling of nutrient-rich water promoted stromatolite development within reefs and Halimeda growth on adjacent slopes. Lastly, microbial carbonates (stromatolites and thrombolites) attained giant dimensions during the late Messinian, which can be regarded as a measure of their success in occupying a variety of ecological niches. This abundance of available habitats is believed to have resulted from the Messinian "salinity crisis", which was followed by a re-colonization of the western Mediterranean. In this context stromatolite proliferation was due to opportunism of microbial communities in colonizing the new environments, rather than to a complete absence of other competitive biota. We do not believe that hypersaline conditions were a causal factor in stromatolite development because of the normal-marine biota associated with them.

  9. Chronostatigraphic basin framework for Palaeoproterozoic rocks (1730-1575 Ma) in northern Australia and implications of base-metal mineralisation

    International Nuclear Information System (INIS)

    The new chronostratigraphic subdivision for Palaeoproterozoic rocks of northern Australia provides an improved framework for future resource exploration. The nine supersequence boundaries identified in the ca 1730-1575Ma Calvert and Isa Superbasins enable the timing of major tectonic events and their stratigraphic response to be better understood. Third- and 4th-order sequence boundaries facilitate the determination of stratigraphic architecture, ultimately providing the necessary information for constraining the flow of fluids in these basins. SHRIMP zircon ages are essential for determining the magnitude of depositional hiatuses at supersequence and some sequence boundaries, and together with palaeomagnetic data provide independent age constraints for the sequence interpretations. Pb/Pb model ages for the world class Broken Hill, Mt Isa, McArthur River and Century Zn Pb Ag deposits coincide with tectonic events recorded at the Gun, Loretta, River Supersequence boundaries and the superbasin boundary formed during closure of the Isa Superbasin during D2 at Mt Isa. The coincidence of a Pb/Pb model age for Broken Hill with an apparent polar wander path inflection at the Gun Supersequence boundary indicates that the regional chronostratigraphic basin framework developed for northern Australia is applicable to rocks of similar age elsewhere in Australia. Furthermore, if the ultimate cause of these inflections is interplate stress, the basin framework should be globally applicable. Hand-held spectrometers provide an efficient and cost-effective method for collecting gamma-ray data from outcrops. The resulting gamma-ray curves permit more accurate correlation with subsurface stratigraphies and together with facies information facilitate the identification of stratigraphic sequences and their bounding stratal surfaces, the essential building blocks of regional chronostratigraphic correlations. Contrary to general belief most of the sections measured in this study preserve their original gamma-ray signal and are not significantly altered by K-metasomatism, fluid-flow events. The absence of these overprints from the regional datasets suggests a local distribution for the fluids responsible for K-metasomatism. Copyright (2000) Geological Society of Australia

  10. The Lower Cretaceous in sedimentary basins of the Brazil south-eastern border: isotopic analysis and their paleoecological implications

    International Nuclear Information System (INIS)

    Carbon isotope data of bitumen, and carbon and oxygen isotope data of limestone provided additional knowledge to the sedimentation environment of the Lower Cretaceous sedimentary sequences of Campos and Espirito Santo basins. In the Buracica stage the carbon isotope data of bitumen suggest a deposition in fresh water lake. The isotope data of bitumen and limestone from lower and middle section of Jiquia stage could indicate a sedimentation in fresh water lake but gradually more saline on the top. More positive ? 13C values of limestone in the upper portion of the Jiquia stage and in the Alagoas stage suggest a restrict marine environment or deposition in hippersaline lakes. During the Albian, the carbonate sedimentation could have occurred still in a marine environment and above normal salinity. According to ? 18O data, the surface waters were warm, with a tendency to become gradually cooler towards the top of Albian. (author)

  11. Assessing Potential Implications of Climate Change for Long-Term Water Resources Planning in the Colorado River Basin, Texas

    Science.gov (United States)

    Munevar, A.; Butler, S.; Anderson, R.; Rippole, J.

    2008-12-01

    While much of the focus on climate change impacts to water resources in the western United States has been related to snow-dominated watersheds, lower elevation basins such as the Colorado River Basin in Texas are dependent on rainfall as the predominant form of precipitation and source of supply. Water management in these basins has evolved to adapt to extreme climatic and hydrologic variability, but the impact of climate change is potentially more acute due to rapid runoff response and subsequent greater soil moisture depletion during the dry seasons. The Lower Colorado River Authority (LCRA) - San Antonio Water System (SAWS) Water Project is being studied to conserve water, develop conjunctive groundwater supplies, and capture excess and unused river flows to meet future water needs for two neighboring regions in Texas. Agricultural and other rural water needs would be met on a more reliable basis in the lower Colorado River Basin through water conservation, surface water development and limited groundwater production. Surface water would be transferred to the San Antonio area to meet municipal needs in quantities still being evaluated. Detailed studies are addressing environmental, agricultural, socioeconomic, and engineering aspects of the project. Key planning activities include evaluating instream flow criteria, water quality, bay freshwater inflow criteria, surface water availability and operating approaches, agricultural conservation measures, groundwater availability, and economics. Models used to estimate future water availability and environmental flow requirements have been developed largely based on historical observed hydrologic data. This is a common approach used by water planners as well as by many regulatory agencies for permit review. In view of the project's 80-yr planning horizon, contractual obligations, comments from the Science Review Panel, and increased public and regulatory awareness of climate change issues, the project team is exploring climate change projections and methods to assess potential impacts over the project's expected life. Following an initial qualitative risk assessment, quantitative climate scenarios were developed based on multiple coupled atmosphere-ocean general circulation model (AOGCM) simulations under a range of global emission scenarios. Projected temperature and precipitation changes were evaluated from 112 downscaled AOGCM projections. A Four scenarios were selected for detailed hydrologic evaluations using the Variable Infiltration Capacity (VIC) macroscale model. A quantile mapping procedure was applied to map future climatological period change statistics onto the long-term natural climate variability in the observed record. Simulated changes in runoff, river flow, evaporation, and evapotranspiration are used to generate adjustments to historical hydrology for assessment of potential changes to surface water availability, river water quality, riverine habitat, and Bay health. Projected temperature, precipitation, and atmospheric CO2 concentrations are used to estimate changes in agricultural demand. Sea level rise scenarios that include trends in Gulf Coast shelf subsidence are combined with changes in inflows to evaluate increased coastal erosion, upland migration of the estuary, and changes to the salinity regime. Results of the scenario-based analyses are being considered in the development of adaptive management strategies for future operations of the system and the proposed project.

  12. The economics of irrigated paddy in Usangu Basin in Tanzania: water utilization, productivity, income and livelihood implications

    Science.gov (United States)

    Kadigi, Reuben M. J.; Kashaigili, Japhet J.; Mdoe, Ntengua S.

    Globally, there is a general lack of consensus on how the available water resources can be allocated efficiently and equitably among its competing uses. In irrigated agriculture, this decodes to the central question of how this sector can be balanced in the manner that it produces more ‘crops per drop’ using less water and releasing adequate water for use by other sectors while concurrently enhancing rural income and livelihoods. This requires that the values and costs of irrigated agriculture, at all levels, are well understood and appropriate interventions made. Based on this ground, this paper presents an economic analysis of the value of irrigated paddy in Usangu basin. It attempts to answer the question of what will be the effects if farmers in Usangu stop producing irrigated paddy. The analysis shows that: (a) about 576 mm 3 of water--currently consumed in paddy irrigation, or 345.6 mm 3--traded inter-regionally as “virtual water” would be utilized in alternative ways, either as evaporation from seasonal swamps within the basin or made available for other intersectoral uses, (b) there will be a shrinkage in the annual paddy supply (both at the local and national levels) of about 105,000 t of paddy (66,000 t of rice)-equivalent to 14.4% of the total annual paddy production in Tanzania, (c) an opportunity cost of about US15.9 million will be incurred annually (equivalent to US530.95 per annum per household practicing irrigated paddy in Usangu), and d) the country’s current account of the balance of payments will be affected by an average of US$15.9 million per annum. The effect will either be in form of annual decline in rice exports or increase in imports depending on the country’s supply and demand for rice.

  13. Hydrogeochemical assessment of arsenic in groundwater and its policy implication: a case study in Terai Basin, Nepal

    Science.gov (United States)

    Gurung, J. K.; Upreti, B. N.; Kansakar, D. R.

    2007-12-01

    Arsenic contamination at levels above the WHO guideline (10 ìg/l) in groundwater is a worldwide problem due to its detrimental effects on health and now known to be a problem also in the Terai Basin of Nepal, posing a serious threat to more than 10 million people. The distribution of arsenic in the basin, however, is patchy. The study emphasizes on the three different types of research into an interdisciplinary package that can be immediately useful to government agencies in Nepal trying to deal with groundwater contamination. They are: hydrogeological assessment of water sources and flow, geochemical analysis of groundwater, and assessment of practical public policy. Basic geochemical analysis gives the abundance and distribution of arsenic along with other physico-chemical parameters of groundwater, whereas, the hydrogeological assessment as an integral part of this study that assist in determining process of mobilization or attenuation of arsenic. Arsenic levels and other key parameters mainly pH, electrical conductivity, chemical oxygen demand, iron, and biological parameter as E-coli were observed at the various locations with different transmissivity values. The study suggests that the flushing rate of an aquifer plays an important role in arsenic content. High flushing rates of an aquifer lead to low levels of arsenic, however the mechanism of this process is still under study. Transmissivity the property of an aquifer that measures the rate at which ground water moves horizontally through a unit is the main factor for controlling flushing. Concentration maps overlaying the base transmissivity map reveals relation of groundwater movement and arsenic concentration. Understanding the relationship between groundwater movement and arsenic content helps planners protect uncontaminated aquifers from future contamination. Also assessment of public policy related to groundwater has identified important changes needed in the existing policy.

  14. Implications for Ecosystem Services of Watershed Processes that affect the Transport and Transformations of Mercury in an Adirondack Stream Basin

    Science.gov (United States)

    Burns, D. A.; Riva-Murray, K.; Bradley, P. M.

    2012-12-01

    Mercury (Hg) is a potent neurotoxin that can affect the health of humans and wildlife through the ingestion of methyl Hg. Mercury contamination of ecosystems originates from human activities such as mining, coal burning and other industrial emissions, and the use of Hg-containing products. Natural sources such as volcanic and geothermal emissions and the weathering of Hg-bearing minerals also contribute to Hg contamination, but are believed to be minor sources in most ecosystems. Various ecosystem disturbances including fires, forest harvesting, and the submergence of land by impoundment may also contribute to Hg ecosystem contamination by mobilizing stores that have previously originated from the sources described above. Mercury from a mix of regional and global emissions sources is transported in the atmosphere to remote landscapes that are distant from local emissions sources. The Adirondacks of New York State is a forested, mountainous region characterized by abundant lakes and streams, and is distant from local emissions sources. Recreational fishing, wildlife viewing, hiking, and hunting are valued ecosystem services in this region. Here, we report on the relevance to ecosystem services of findings based on five years of Hg data collection of stream water, groundwater, invertebrates, and fish in the upper Hudson River basin in the central part of the Adirondack region. The New York State Dept. of Health has issued fish consumption advisories for the entire Adirondacks based on elevated levels previously measured in lakes and rivers of this region. Our work seeks improved understanding and models of the landscape sources and watershed processes that control the transformation of Hg to its methyl form (MeHg), the transport of MeHg to streams, and bioaccumulation of MeHg in aquatic food webs. Mean annual atmospheric Hg deposition was 6.3 ?g/m2/yr during 2007-09, compared to mean annual filtered total Hg stream yields of 1.66 ?g/m2/yr and filtered MeHg stream yields of 0.095 ?g/m2/yr in a sub-basin of the upper Hudson during this same period. Our work shows that Hg in stream biota, which is largely in the methyl form, is strongly related to MeHg measured in the water column; food web factors that affect Hg bioaccumulation also play a role. In brook trout, the top aquatic predator in the food web of the upper Hudson, Hg concentrations average about 0.1 ?g/g, a level believed to affect fish behavior, and a few values were greater than 0.3 ?g/g, a level at which human fish consumption advisories are issued. Landscape-based regression models that account for about 80% of the variation in stream MeHg concentrations at 25 sites across the upper Hudson basin include metrics of riparian area and open water indicating the importance of these landscape types in affecting methylation rates, losses of MeHg (through demethylation and other processes), and the transport of MeHg to surface waters. These and other study results indicate that factors such as watershed geomorphology, seasonal variations in discharge and air temperature, and the location and connection of riparian wetlands to streams are the strongest factors that affect stream MeHg concentrations and therefore, the potential ecosystem services provided by fish and other wildlife in the Adirondack region.

  15. The population structure of Glossina fuscipes fuscipes in the Lake Victoria basin in Uganda: implications for vector control

    Directory of Open Access Journals (Sweden)

    Hyseni Chaz

    2012-10-01

    Full Text Available Abstract Background Glossina fuscipes fuscipes is the primary vector of trypanosomiasis in humans and livestock in Uganda. The Lake Victoria basin has been targeted for tsetse eradication using a rolling carpet initiative, from west to east, with four operational blocks (3 in Uganda and 1 in Kenya, under a Pan-African Tsetse and Trypanosomiasis Eradication Campaign (PATTEC. We screened tsetse flies from the three Ugandan PATTEC blocks for genetic diversity at 15 microsatellite loci from continental and offshore populations to provide empirical data to support this initiative. Methods We collected tsetse samples from 11 sites across the Lake Victoria basin in Uganda. We performed genetic analyses on 409 of the collected tsetse flies and added data collected for 278 individuals in a previous study. The flies were screened across 15 microsatellite loci and the resulting data were used to assess the temporal stability of populations, to analyze patterns of genetic exchange and structuring, to estimate dispersal rates and evaluate the sex bias in dispersal, as well as to estimate demographic parameters (NE and NC. Results We found that tsetse populations in this region were stable over 4-16 generations and belong to 4 genetic clusters. Two genetic clusters (1 and 2 corresponded approximately to PATTEC blocks 1 and 2, while the other two (3 and 4 fell within PATTEC block 3. Island populations grouped into the same genetic clusters as neighboring mainland sites, suggesting presence of gene flow between these sites. There was no evidence of the stretch of water separating islands from the mainland forming a significant barrier to dispersal. Dispersal rates ranged from 2.5?km per generation in cluster 1 to 14?km per generation in clusters 3 and 4. We found evidence of male-biased dispersal. Few breeders are successfully dispersing over large distances. Effective population size estimates were low (33–310 individuals, while census size estimates ranged from 1200 (cluster 1 to 4100 (clusters 3 and 4. We present here a novel technique that adapts an existing census size estimation method to sampling without replacement, the scheme used in sampling tsetse flies. Conclusion Our study suggests that different control strategies should be implemented for the three PATTEC blocks and that, given the high potential for re-invasion from island sites, mainland and offshore sites in each block should be targeted at the same time.

  16. The Changing Nature of Water Storage in the Great Lakes Basin and its Implications for Future Sustainability

    Science.gov (United States)

    Cherkauer, K. A.

    2012-12-01

    Home to approximately 40 million people in the United States and Canada, the Great Lakes drainage basin is a tremendous freshwater resource. It is, however, undergoing significant changes both in land use and climate. It has suffered from substantial deforestation in the last century and the continued drainage of wetlands. Reforestation, urbanization and increased demand for agricultural production on less land are all changing the face of the region. Climate is also changing with warmer, wetter winters changing the accumulation of snow and the formation of lake and soil ice. When land use and climate are relatively consistent between years, the storage of water in and on the land surface can be neglected for inter-annual analysis of the regional water balance, however, given the observed and projected future changes to the region it is clear that representing changes in storage will be critical for understanding how hydrology in the region will respond. As nearly half of the freshwater supply to the Great Lakes is in the form of land surface runoff, changes in the volume and timing of water storage within the drainage basin is a critical factor in the future health and sustainability of their ecosystem. Unlike air temperature and precipitation which are fairly well known in the region, many of these storage variables are known at only a handful of locations if they are monitored at all. Therefore, hydrology model become indispensable tools when trying to quantify changes in storage. For this presentation, observed and simulated datasets are used to identify and quantify changes in the timing and quantity of storage within the Great Lakes region due to changes in land use and climate. Storage terms that will be evaluated include soil moisture and ice, snow cover, groundwater, and inland lake and wetland storage. Warmer winters are reducing snow cover, which can lead to the formation of more soil ice and wetter spring soils for a time, though increasing temperatures will get warm enough to reduce the formation of soil ice as well. Wetter and warmer conditions in the winter and spring can lead to earlier spring runoff, though the presence of lake and wetland storage can mitigate this effect. Wetlands and lakes increase infiltration and the potential for groundwater recharge, while the expansion of urban impervious area reduces infiltration and recharge.

  17. Hydrogeochemical zonation and its implication for arsenic mobilization in deep groundwaters near alluvial fans in the Hetao Basin, Inner Mongolia

    Science.gov (United States)

    Jia, Yongfeng; Guo, Huaming; Jiang, Yuxiao; Wu, Yang; Zhou, Yinzhu

    2014-10-01

    High As groundwater has been found in shallow aquifers of the flat plain of the Hetao basin, but little is known about As concentration in deep groundwaters around piedmont areas, which are the major drinking water resources. One hundred and three groundwater samples from wells with depths >50 m and seven samples from one multi-level monitoring well (89 m in depth) were analyzed for chemical compositions and 18O and D isotopes to examine the geochemical processes controlling As mobilization. According to hydrogeological setting, chemical and isotopic characteristics of deep groundwater, three distinguished hydrogeochemical zones are delineated, including Recharge-Oxic Zone (Zone I), Groundwater Flow-Moderate Reducing Zone (Zone II), and Groundwater Flow-Reducing Zone (Zone III). Zone I is located in proximal fans in the recharge area with oxic conditions, where low As groundwater generally occurs. In Zone II, located in the intermediate between the fans and the flat plain with Fe-reduction predominated, groundwater As is moderate. Zone III lies in the flat plain with the occurrence of SO42- reduction, where high As groundwater is mostly found. This indicates that release of As to groundwater is primarily determined by reduction sequences. Arsenic is immobilized in O2 /NO3- reduction stage in Zone I and released in Fe-reducing conditions of Zone II, and displays a significant elevated concentration in SO4-reducing stage in Zone III. Dissolution of carbonate minerals occurs in Zone I, while Ca2+ and Mg2+ are expected to precipitate in Zone II and Zone III. In the multi-level monitoring well, both chemical and isotopic compositions are dependent of sampling depths, with the similar trend to the hydrogeochemical zonation along the flow path. The apparent increases in ?D and ?18O values in Zone III reveal the possibility of high As shallow groundwater recharge to deep groundwater. It indicates that deep groundwaters in proximal fans have low As concentrations and are considered as safe drinking water resources in the Hetao basin. However, high As concentration is frequently observed in deep groundwater in the flat plain, which should be routinely monitored in order to avoid chronic As poisoning.

  18. 2D Seismic Interpretation of the Tumaco on-and offshore basin, SW Colombia. Implications for tectono-stratigraphic evolution and hydrocarbon exploration

    OpenAIRE

    Campiño Restrepo, Luisa Fernanda

    2013-01-01

    The Tumaco on and offshore basin is located in the Pacific region of NW corner of South America, southwestern Colombia. It is classified as a forearc basin and it is considered a frontier exploration basin. The basin was formed during Paleogene-Recent convergence of oceanic derived terranes against South America. The stratigraphy consists of a volcano-clastic basement overlie by an Eocene to Recent clastic sedimentary cover. The last exploratory well, drilled in the 80’s, showed non-commercia...

  19. A new species of Corydoras Lacépède (Siluriformes: Callichthyidae from the Rio Tapajós basin and its phylogenetic implications

    Directory of Open Access Journals (Sweden)

    Vinicius C. Espíndola

    2014-01-01

    Full Text Available A new species of Corydoras is described from tributaries of the rio Arinos, rio Teles Pires and rio Preto, all in the rio Tapajós basin. The new species is a member of a group that includes 36 species with spots on the body. Within this group, the new species can be readily distinguished by having a smaller dorsal-fin spine than the first three subsequent soft dorsal-fin rays; pectoral, pelvic and anal fins hyaline; dorsal-fin interradial membrane hyaline; rounded spots on trunk restricted to dorsolateral body plates and dorsal portion of ventrolateral body plates, not reaching the base of pelvic and anal fins. The new species can be further distinguished from Corydoras xinguensis by having spots with diffuse edges, and from all other species of spotted Corydoras except C.multimaculatus, by the absence of ventral platelets. A phylogenetic analysis recovered the new species plus Corydoras metae and C.araguaiensis in a clade sharing the presence of a pointed process on the maxilla for insertion of the retractor tentaculi muscle. In addition, the presence in the new species of an elongated anterior portion of the mesethmoid and a triangular uncinate process of the epibranchial 3 suggests a close relationship with Corydoras metae.

  20. Biostratigraphic and palaeoenvironmental implications of an Early Cretaceous miospore assemblage from the Muling Formation, Jixi Basin, northeast China

    Energy Technology Data Exchange (ETDEWEB)

    Yang, X.J.; Li, W.B.; Batten, D.J. [Chinese Academy of Sciences, Nanjing (China)

    2007-04-15

    In the Jixi Basin, eastern Heilongjiang Province, China, the lower part of the Lower Cretaceous succession consists of coal-bearing strata including the Muling Formation, which, in addition to plant megafossils, yields abundant spores and pollen grains and a few dinoflagellate cysts. The spore-pollen assemblage consists of more than 42 species belonging to 34 genera. Most of these are derived from pteridophytes and gymnosperms. The association of Aequitriradites echinatus, Cicatricosisporites australiensis, C. imbricatus, C. mediostriatus, C. undosus, Contignisporites glebulentus, Crybelosporites punctatus, Foranminisporis asymmetricus, Gleicheniidites laetus, Impardecispora purverulenta, Kuylisporites lunaris, Pilosisporites trichopapillosus and Triporoletes singularis suggests that the formation is unlikely to be older than late Hauterivian and younger than Aptian, with emphasis placed on the Barremian-early Aptian. The composition of the dinoflagellate cyst and plant megafossil assemblages is consistent with this determination. Based on palynofloral content, a comparison between the miospores recovered and the spores and pollen produced by extant plant taxa, the associated plant megafossils, and the sedimentary facies that characterize the Muling Formation, it is concluded that the source vegetation was dominated by ferns and that the climate was wet subtropical but seasonally dry.

  1. Geochemical and isotopic anomalies preceding K/T boundary in the Cauvery basin, South India : implications for end Cretaceous events

    International Nuclear Information System (INIS)

    The Upper Cretaceous-Lower Tertiary deposits of the Cauvery basin show prominent geochemical and isotopic anomalies preceding the K/T boundary. Analysis of stratigraphic variations of whole-rock elemental concentrations and stable isotopic compositions in the light of sedimentation history, petrography and mineralogy of the rocks reveal that these anomalies may be due to increased detrital influx caused by sea-level and climatic changes, Deccan volcanism and release of volatile gases from buried hydrocarbons, presumably gas hydrates. Comparison of these interpretations with that of K/T sites located in Guatemala, New Mexico and Israel revealed that these interpretations are in conformity with records on gradually increasing environmental stress during Upper Cretaceous that culminated with two major catastrophic events such as bolide impact and Deccan Trap volcanism. Thus this communication provides additional support to the growing acknowledgement of the theory that higher faunal turnover across the K/T boundary the world over might have been the result of gradual environmental deterioration rather than a sudden impact in the global scale. (author)

  2. Evidence of syntectonic tephrites with nepheline in the Sidi Saïd Maâchou Cambrian basin (coastal Meseta, Morocco; geodynamic implications

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    El Hatimi, N.

    2009-12-01

    Full Text Available Based on a combined structural, petrographic, and geochemical analysis, a new interpretation of the basic magmatism of Sidi Saïd Maâchou (coastal Meseta in two stages of emplacement is proposed. The first stage is characterized by transitional pyroclastic flows that have accompanied the opening of the West-Mesetian basin, during the Cambrian; the second stage is made of dykes of basalts, dolerites, and tephrites bearing nepheline. The emplacement of this undersaturated alkaline magma is associated to a sinistral submeridian shear zone which has been activated at the end of the Caledonian orogenesis, by a mantellic advection.

    Basée sur des critères structuraux, pétrographiques et géochimiques, une réinterprétation du magmatisme basique de Sidi Saîd Maâchou (meseta côtière en deux stades de mise en place est proposée. Le premier stade est caractérisé par des coulées pyroclastiques transitionnelles accompagnant l’ouverture du bassin ouest mésétien au Cambrien. Le second stade, de nature fissural, comprend des basaltes, dolérites et téphrites à néphéline spécifiques d’un magmatisme alcalin sous-saturé. La mise en place de ce dernier est associée à un couloir de cisaillement senestre subméridien activé à la fin de l’orogenèse calédonienne, engendrant un flux géothermique élevé.

  3. Geochemical evolution of the Tertiary succession of the NW shelf, Bengal basin, Bangladesh: Implications for provenance, paleoweathering and Himalayan erosion

    Science.gov (United States)

    Roy, Dhiman Kumer; Roser, B. P.

    2013-12-01

    Whole rock major, trace and rare earth element (REE) compositions of Paleogene to Neogene sedimentary rocks of the NW shelf succession (Province 1) of Bangladesh contain a record of interaction of the India and Asian plates, Himalayan tectonism, and climatic development. Analyses of 66 sandstones and mudrocks from the Tertiary succession of Bangladesh were made to examine provenance, source weathering, and the influence of paleoclimate and tectonism. The sediments display linear geochemical trends due to quartz dilution, and varying quartz-clay ratios produced by hydrodynamic sorting. Chondrite-normalized REE patterns for both sandstones and mudrocks from different groups are similar to upper continental crust, with moderate to high LREE enrichment (lithotypes within formations average LaN/YbN 5.31-11.41) and marked negative Eu anomalies (Eu/Eu* 0.51-0.69). Based on geochemical criteria the succession can be divided into three parts (Jaintia; Barail-Surma; and Dupi Tila). Very high silica contents in Jaintia Tura sandstones and high Chemical Index of Alteration (CIA) indices in Kopili mudrocks (Fe-shales) suggest derivation from a deeply weathered and stable cratonic source (India). The Tura sandstones are interpreted as first-cycle quartz arenites, produced while the Indian plate drifted across equatorial regions during the Paleocene-Eocene Thermal maximum (PETM). The Barail-Surma and Dupi Tila sediments were derived from a felsic orogen (the Himalaya). The Barail-Surma sediments were mainly derived from the Trans Himalayan Batholith and associated granitoids, with significant contribution from the Lesser Himalaya. Mafic input is also evident, probably from intraoceanic arc material within the Himalaya. Barail mudrocks have uniformly high CIA values (92-95), suggesting intense steady-state weathering of their proto-Himalayan source, and warm and humid climate. In contrast, CIA values of Surma mudrocks range from 66 to 93 (average 84), suggesting non-steady state weathering related to active uplift in the Himalaya. The Dupi Tila sediments were derived from a more felsic Lesser Himalaya source, with significant contribution from the Trans-Himalaya and very little or no ophiolitic or arc material. Dupi Tila mudrocks have CIA ratios of 62-99 (average 72), also indicating non-steady state weathering in the rising Himalayan source. Geochemical compositions of the NW shelf sediments are comparable to coeval successions in the Surma basin (Province 2) of Bangladesh and the Siwaliks (India), indicating similar source. Evolution of the Indian monsoon and associated high precipitation caused intense chemical weathering of the Surma and Dupi Tila source, despite rapid uplift. The Surma Group thus bears the signature of evolution of the Asian monsoon in the Bengal basin at 21 Ma, simultaneous with the development of the East Asian monsoon. This supports proposals that both monsoon systems developed at the same time.

  4. Groundwater geochemistry and its implications for arsenic mobilization in shallow aquifers of the Hetao Basin, Inner Mongolia

    International Nuclear Information System (INIS)

    Arsenic concentrations in shallow groundwaters from the Hetao Basin of Inner Mongolia range between 0.6 and 572 ?g/L. High As groundwaters generally occur in the shallow alluvial-lacustrine aquifers, which are mainly composed of black (or dark grey) fine sands in a reducing environment. They are characterized by high concentrations of dissolved Fe, Mn, HCO3-, P and S2-, and low concentrations of NO3- and SO42-. Low SO42- coupled with high S2- suggests that SO42- reduction has been an active process. In the reducing groundwaters, inorganic As(III) accounts for around 75% of total dissolved As. Total As contents in the sediments from three representative boreholes are observed to be 7.3-73.3 mg/kg (average of 18.9 mg/kg). The total As is mildly-strongly correlated with total Fe and total Mn, while a quite weak correlation exists between total As and total S, suggesting that the As is associated with Fe-Mn oxides, rather than sulfides in the sediments. It is found in the sequential extraction that chemically active As is mainly bound to Fe-Mn oxides, up to 3500 ?g/kg. The mobilization of As under reducing conditions is believed to include reductive dissolution of Fe-Mn oxides and reduction of adsorbed As. Although exchangeable As is labile and very vulnerable to hydrogeochemical condition, the contribution is relatively limited due to the low concentrations. The competition between As and other anions (such as HPO42-) for binding sites on Fe-Mn oxides may also give rise to the release of As into groundwater. Slow groundwater movement helps accumulation of the released As in the groundwaters

  5. Basin Testing of Wave Energy Converters in Trondheim: Investigation of Mooring Loads and Implications for Wider Research

    Directory of Open Access Journals (Sweden)

    Vladimir Krivtsov

    2014-04-01

    Full Text Available This paper describes the physical model testing of an array of wave energy devices undertaken in the NTNU (Norwegian University of Science and Technology Trondheim basin between 8 and 20 October 2008 funded under the EU Hydralabs III initiative, and provides an analysis of the extreme mooring loads. Tests were completed at 1/20 scale on a single oscillating water column device and on close-packed arrays of three and five devices following calibration of instrumentation and the wave and current test environment. One wave energy converter (WEC was fully instrumented with mooring line load cells, optical motion tracker and accelerometers and tested in regular waves, short- and long-crested irregular waves and current. The wave and current test regimes were measured by six wave probes and a current meter. Arrays of three and five similar WECs, with identical mooring systems, were tested under similar environmental loading with partial monitoring of mooring forces and motions. The majority of loads on the mooring lines appeared to be broadly consistent with both logistic and normal distribution; whilst the right tail appeared to conform to the extreme value distribution. Comparison of the loads at different configurations of WEC arrays suggests that the results are broadly consistent with the hypothesis that the mooring loads should differ. In particular; the results from the tests in short crested seas conditions give an indication that peak loads in a multi WEC array may be considerably higher than in 1-WEC configuration. The test campaign has contributed essential data to the development of Simulink™ and Orcaflex™ models of devices, which include mooring system interactions, and data have also been obtained for inter-tank comparisons, studies of scale effects and validation of mooring system numerical models. It is hoped that this paper will help to draw the attention of a wider scientific community to the dataset freely available from the Marintek website.

  6. Climate change and stream temperature projections in the Columbia River Basin: biological implications of spatial variation in hydrologic drivers

    Directory of Open Access Journals (Sweden)

    D. L. Ficklin

    2014-06-01

    Full Text Available Water temperature is a primary physical factor regulating the persistence and distribution of aquatic taxa. Considering projected increases in temperature and changes in precipitation in the coming century, accurate assessment of suitable thermal habitat in freshwater systems is critical for predicting aquatic species responses to changes in climate and for guiding adaptation strategies. We use a hydrologic model coupled with a stream temperature model and downscaled General Circulation Model outputs to explore the spatially and temporally varying changes in stream temperature at the subbasin and ecological province scale for the Columbia River Basin. On average, stream temperatures are projected to increase 3.5 °C for the spring, 5.2 °C for the summer, 2.7 °C for the fall, and 1.6 °C for the winter. While results indicate changes in stream temperature are correlated with changes in air temperature, our results also capture the important, and often ignored, influence of hydrological processes on changes in stream temperature. Decreases in future snowcover will result in increased thermal sensitivity within regions that were previously buffered by the cooling effect of flow originating as snowmelt. Other hydrological components, such as precipitation, surface runoff, lateral soil flow, and groundwater, are negatively correlated to increases in stream temperature depending on the season and ecological province. At the ecological province scale, the largest increase in annual stream temperature was within the Mountain Snake ecological province, which is characterized by non-migratory coldwater fish species. Stream temperature changes varied seasonally with the largest projected stream temperature increases occurring during the spring and summer for all ecological provinces. Our results indicate that stream temperatures are driven by local processes and ultimately require a physically-explicit modeling approach to accurately characterize the habitat regulating the distribution and diversity of aquatic taxa.

  7. Controls on large landslide distribution and implications for the geomorphic evolution of the southern interior Columbia River basin

    Science.gov (United States)

    Safran, E.B.; Anderson, S.W.; Mills-Novoa, M.; House, P.K.; Ely, L.

    2011-01-01

    Large landslides (>0.1 km2) are important agents of geomorphic change. While most common in rugged mountain ranges, large landslides can also be widespread in relatively low-relief (several 100 m) terrain, where their distribution has been relatively little studied. A fuller understanding of the role of large landslides in landscape evolution requires addressing this gap, since the distribution of large landslides may affect broad regions through interactions with channel processes, and since the dominant controls on landslide distribution might be expected to vary with tectonic setting. We documented >400 landslides between 0.1 and ~40 km2 across ~140,000 km2 of eastern Oregon, in the semiarid, southern interior Columbia River basin. The mapped landslides cluster in a NW-SE-trending band that is 50-100 km wide. Landslides predominantly occur where even modest local relief (~100 m) exists near key contacts between weak sedimentary or volcaniclastic rock and coherent cap rock. Fault density exerts no control on landslide distribution, while ~10% of mapped landslides cluster within 3-10 km of mapped fold axes. Landslide occurrence is curtailed to the NE by thick packages of coherent basalt and to the SW by limited local relief. Our results suggest that future mass movements will localize in areas stratigraphically preconditioned for landsliding by a geologic history of fluviolacustrine and volcaniclastic sedimentation and episodic capping by coherent lava flows. In such areas, episodic landsliding may persist for hundreds of thousands of years or more, producing valley wall slopes of ~7??-13?? and impacting local channels with an evolving array of mass movement styles. ?? 2011 Geological Society of America.

  8. Paleoclimatic implications of fossil shoreline deposits in the southern basin and range province during the Pleistocene-Holocene transition

    Science.gov (United States)

    Kowler, A. L.

    2010-12-01

    Paleolake shoreline deposits throughout the southern Basin and Range (SBAR) signify past intervals of steady-state climatic conditions occuring during the late Pleistocene slightly before, as well as after the Last Glacial Maximum (LGM; ~23-19 Ka). Unfortunately, a lack of knowledge about the age of fossil shoreline deposits—due to C-14 related uncertainties and incomplete dating of shorelines—has resulted in a large gap in our knowledge about past climatic and surface hydrologic conditions in the SBAR. Several studies collectively reveal multiple lake level oscillations during the LGM and last part of the Pleistocene, with reasonably well dated shoreline deposits existing for only four paleolakes: one in central New Mexico (Estancia), two in southwestern New Mexico (Playas and Cloverdale), and one in southeastern Arizona (Cochise). In summary, there is evidence for a pre-LGM high-stand at Cochise (>26 Ka), LGM high-stands at Estancia and Cloverdale (>20-16 Ka), deglacial age high-stands at Playas and Cochise (16-13 Ka), and latest Pleistocene-early Holocene still stands of as yet undetermined elevation at Playas and Estancia (13-9K). Further, the absence of high-stands from 11-10 Ka suggests that the Younger Dryas climatic reversal—which is detected in the stable O isotopic composition of speleothems from Cave-of-the-Bells in southeastern Arizona—was marked there by a decrease in mean annual air temperature without a significant increase in precipitation. Alternatively, if a return to glacial precipitation levels did occur, then it was for an interval so short that sedimentological evidence was not preserved. This presentation will cover the afore mentioned chronologies, along with discussion about associated atmospheric circulation patterns in the SBAR and across western North America.

  9. Detrital Mineral Record of the Central Myanmar Basin and implications for the evolution of the eastern Himalayan margin

    Science.gov (United States)

    Brezina, C. A.; Robinson, R. A. J.; Barfod, D. N.; Carter, A.; Parrish, R. R.; Horstwood, M. S.; Thein, M.; Win Oo, N.

    2014-12-01

    Single grain detrital thermochronology (40Ar/39Ar white mica, zircon fission track and Lu-Hf analysis) of Eocene, Oligocene and Miocene sedimentary rocks from the Central Myanmar Basin permits the identification of tectonothermal events in the source areas, and an understanding of how exhumation histories and changing provenance are related to the palaeogeography of the West Burma block during India-Asia collision. Robinson et al. (2014) used detrital zircon U-Pb and Lu-Hf isotopic analysis to show that Eocene and Oligocene sedimentary rocks were primarily sourced from the Gangdese magmatic arc that lies exclusively within the southern Lhasa terrane, and that the Yarlung Tsangpo and Irrawaddy River were connected at this time. Detrital thermochronology reveal these Paleogene deposits contain broadly distributed, mainly pre-Himalayan 40Ar/39Ar white mica cooling ages, reflecting the contribution from multiple source areas with a cooling history that is similar to the Lhasa terrane. A distinct change in provenance to a single, sustained source area during deposition of the Miocene units is recorded by a white mica 40Ar/39Ar cooling age peak of 37 Ma and a lesser peak of 17 - 21 Ma that is also observed in detrital zircon fission track age data. These two age peaks, 37 Ma and 17 - 21 Ma, likely reflect an initial period of crustal thickening, metamorphism and exhumation in the southern Mogok Metamorphic Belt, and a later phase of exhumation associated with deformation in the eastern syntaxis and the onset of extension in Myanmar and other parts of SE Asia. The latter events are also associated with the disconnection of the Yarlung Tsangpo from the Irrawaddy River around 18 Ma (Robinson et al., 2014). The combined dataset provides constraints on the position and movement of the West Burma block from the Late Eocene to Early Miocene, supports an Oligocene (~37 Ma) age for the timing of India-West Burma-Sibumasu coupling, and an Early Miocene age for extension-related exhumation associated with deformation in the eastern Himalayan region. Robinson, RAJ, Brezina, CA, Parrish, RR, Horstwood, MSA, Nay Win, O, Bird, MI, Myint, T, Walters, AS, Oliver, GJH, and Khin, Z, (2014) Large rivers and orogens: The evolution of the Yarlung Tsangpo-Irrawaddy system and the eastern Himalayan syntaxis: Gondwana Research, 26, 112-121.

  10. A new species of Corydoras Lacépède (Siluriformes: Callichthyidae) from the Rio Tapajós basin and its phylogenetic implications

    Scientific Electronic Library Online (English)

    Vinicius C., Espíndola; Marcelo R.S., Spencer; Leandro R., Rocha; Marcelo R., Britto.

    Full Text Available Uma nova espécie de Corydoras é descrita dos tributários dos rios Arinos, Teles Pires e Preto, bacia do rio Tapajós. A nova espécie é membro de um grupo com pontilhados no corpo que inclui 36 espécies. Dentro desse grupo, a nova espécie pode ser facilmente distinguida pelo espinho dorsal menor que o [...] s três primeiros raios ramificados da nadadeira dorsal; nadadeiras peitorais, pélvicas e anal hialinas; membranas inter-radiais da nadadeira dorsal hialina; presença de pontilhados redondos no tronco restritas as placas dorsolaterais do corpo e porções dorsais das placas ventrolaterais não alcançando a base das nadadeiras pélvicas e anal. A nova espécie pode ser distinguida de Corydoras xinguensis por pontilhados com margens difusas e das demais espécies de Corydoras com pontilhado, exceto em C.multimaculatus, pela ausência de pequenas placas ventrais. Uma análise filogenética recuperou a nova espécie mais Corydoras metae e C.araguaiensis em um agrupamento compartilhando a presença de um processo pontiagudo para inserção do músculo retractor tentaculi no maxilar. A porção anterior do mesetmóide alongada e o processo uncinado do epibranquial 3 triangular indicam uma relação mais próxima com Corydoras metae. Abstract in english A new species of Corydoras is described from tributaries of the rio Arinos, rio Teles Pires and rio Preto, all in the rio Tapajós basin. The new species is a member of a group that includes 36 species with spots on the body. Within this group, the new species can be readily distinguished by having a [...] smaller dorsal-fin spine than the first three subsequent soft dorsal-fin rays; pectoral, pelvic and anal fins hyaline; dorsal-fin interradial membrane hyaline; rounded spots on trunk restricted to dorsolateral body plates and dorsal portion of ventrolateral body plates, not reaching the base of pelvic and anal fins. The new species can be further distinguished from Corydoras xinguensis by having spots with diffuse edges, and from all other species of spotted Corydoras except C.multimaculatus, by the absence of ventral platelets. A phylogenetic analysis recovered the new species plus Corydoras metae and C.araguaiensis in a clade sharing the presence of a pointed process on the maxilla for insertion of the retractor tentaculi muscle. In addition, the presence in the new species of an elongated anterior portion of the mesethmoid and a triangular uncinate process of the epibranchial 3 suggests a close relationship with Corydoras metae.

  11. B.C. Hydro Williston to Kelly Lake 500 kV transmission line public consultation report

    International Nuclear Information System (INIS)

    A public consultation program was developed and implemented for a proposed third 500-kV transmission line from Williston Substation, east of Prince George in British Columbia, to Kelly Lake Substation near Clinton, British Columbia. The implemented program took place from July 1989 to January 1990 and involved discussions with about 14 local and regional governments and community associations, and 30 special interest groups. Eight public meetings were held as well as three meetings with native groups. A total of 73 public information requests were logged. The public consultation program was sufficiently comprehensive and objective to identify the public's concerns with respect to the proposed line. The overall goal of the program was to improve the project by incorporating public ideas and concerns into the planning process. It is believed that some important examples of how this has occurred on this project include a closer working relationship between British Columbia Hydro and property owners along the transmission line corridor, improved right-of-way clearing and maintenance standards, identification of ways to improve the economic benefits of the project to local contractors, improved public awareness about electric and magnetic fields, and an enhanced awareness of the utility's commitment to public consultation. 2 figs

  12. Paleoclimatic implications (Late Cretaceous-Paleogene) from micromorphology of calcretes, palustrine limestones and silcretes, southern Paraná Basin, Uruguay

    Science.gov (United States)

    Tófalo, Ofelia R.; Pazos, Pablo J.

    2010-04-01

    Sedimentologic and petrographic analyses of outcroping and subsurface calcretes, palustrine carbonates, and silcretes were carried out in the southern Paraná Basin (Uruguay). The aim of this work is to describe the microfabric and interpret the genesis of these rocks through detailed analyses, since they contain significant paleoenvironmental and paleoclimatic evolution information. The main calcrete and silcrete host rock (Mercedes Formation) is represented by a fluvial thinning upward succession of conglomerate and sandstone deposits, with isolated pelitic intervals and paleosoils. Most of the studied calcretes are macroscopically massive with micromorphological features of alpha fabric, originated by displacive growth of calcite in the host clastic material due to evaporation, evapotranspiration and degassing. Micromorphologically, calcretes indicate an origin in the vadose and phreatic diagenetic environments. Micrite is the principal component, and speaks of rapid precipitation in the vadose zone from supersaturated solutions. The abundance of microsparite and secondary sparite is regarded as the result of dissolution and reprecipitation processes. Although present, brecciated calcretes are less common. They are frequent in vadose diagenetic environments, where the alternation between cementation and non-tectonic fracturing conditions take place. These processes generated episodes of fragmentation, brecciation and cementation. Fissures are filled with clear primary sparitic calcite, formed by precipitation of extremely supersaturated solutions in a phreatic diagenetic environment. The micromorphological characteristics indicate that calcretes resulted from carbonate precipitation in the upper part of the groundwater table and the vadose zone, continuously nourished by lateral migration of groundwater. The scarcity of biogenic structures suggests that they were either formed in zones of little biological activity or that the overimposed processes related to water table fluctuations produced intense recrystallization completely obliterating the biogenic fabric. Limestone beds containing terrestrial gastropods are geographically restricted. Situated at the top of the calcrete successions, they exhibit brecciated and peloidal-intraclastic textures but lack lamination, edaphic structures, aggregates and vertical rhizoliths. This indicates they correspond to low-energy palustrine deposits, generated in shallow, local and ephemeral ponds developed in topographic depressions. When water table levels dropped, the palustrine deposits were exposed. This favours the presence of terrestrial gastropods, seeds and insect nests. The combination of calcretes and palustrine carbonates indicates periods and areas with a reduced clastic input and a predominantly semiarid climate, with well-defined humid and dry seasons. Characteristics of the later developed massive and nodular horizons of silcretes, such as, preservation of the internal structure of the host rock, the small areal extent, the formation of massive lenses, the complex pore infillings and the lack of a columnar upper section, indicate that they were generated from groundwaters. Every silcretized horizon shows different positions of the groundwater table and relates to the dissection of landscape. The age of calcretization and silcretization is bracketed between the Late Cretaceous (Campanian-Maastrichtian) and the Early Eocene. Paleoclimate indicates changing conditions from warm and humid at the end of the Cretaceous (Mercedes Formation) to semiarid and seasonal during Paleocene (groundwater calcretes and palustrine deposits) and subtropical and seasonal in the early Eocene (Asencio Formation).

  13. Sedimentology and paleogeographic evolution of the intermontane Kathmandu basin, Nepal, during the Pliocene and Quaternary. Implications for formation of deposits of economic interest

    Energy Technology Data Exchange (ETDEWEB)

    Dill, H.G.; Kharel, B.D.; Singh, V.K.; Piya, B.; Busch, K.; Geyh, M. [Federal Institute of Geoscience & Natural Resources, Hannover (Germany)

    2001-07-01

    The Kathmandu Valley is an intermontane basin in the center of a large syncline of the Lesser Himalayas. The sedimentary basin fill comprises three units of Plio-Pleistocene to Holocene age. The study aimed at modeling the paleogeographic evolution of the basin, with emphasis on sedimentary series of fossil fuels and non-metallic deposits. The lithological setting of the basin and the tectonic framework were instrumental to basin subsidence. The results of this basin analysis may be used predictively in the exploration for coal, natural gas, diatomaceous earths and quarrying for sand or clay. The gas potential is at its maximum in the lacustrine facies, sand and clay for construction purposes may be quarried economically from various fluvial and deltaic deposits. Diatomaceous earths predominantly accumulated in marginal parts of the lake and some landslide-dammed ponds. Lignitic brown coal can be mined together with combustible shales from poorly drained swamps.

  14. Organic geochemistry of deep ground waters from the Palo Duro Basin, Texas: implications for radionuclide complexation, ground-water origin, and petroleum exploration

    International Nuclear Information System (INIS)

    This report describes the organic geochemistry of 11 ground-water samples from the Palo Duro Basin, Texas and discusses the implications of their organic geochemical compositions in terms of radionuclide complexation, ground-water origin, and the petroleum potential of two candidate repository sites in Deaf Smith and Swisher Counties. Short-chain aliphatic acid anions are the principal organic constituents present. Stability constant data and simple chemical equilibria calculations suggest that short-chain aliphatic acids are relatively weak complexing agents. The extent of complexation of a typical actinide by selected inorganic ligands present in these brines is expected to far outweigh actinide complexation by the aliphatic acid anions. Various lines of evidence suggest that some portion of the bromide concentrations in the brines is derived from the same source as the short-chain aliphatic acid anions. When the postulated organic components are subtracted from total bromide concentrations, the origins of the Palo Duro brines, based on chloride versus bromide relationships, appear largely consistent with origins based on isotopic evidence. The short-chain aliphatic acid anion content of the Palo Duro brines is postulated to have been much greater in the geologic past. Aliphatic acid anions are but one of numerous petroleum proximity indicators, which consistently suggest a greater petroleum exploration potential for the area surrounding the Swisher County site than the region encompassing the candidate site in Deaf Smith County. Short-chain aliphatic acid anions appear to provide a useful petroleum exploration tool as long as the complex reactions that may dimish their concentrations in ground water are recognized. 71 refs., 10 figs., 10 tabs

  15. Magnetostratigraphy of Cenozoic deposits in the western Qaidam Basin and its implication for the surface uplift of the northeastern margin of the Tibetan Plateau

    Science.gov (United States)

    Chang, Hong; Li, Leyi; Qiang, Xiaoke; Garzione, Carmala N.; Pullen, Alexander; An, Zhisheng

    2015-11-01

    Thick Cenozoic deposits in the northwestern Qaidam Basin record erosion of the Altyn Tagh and high terrain west of that basin and presumably the concurrent growth of the northeastern Tibetan Plateau. A detailed magnetostratigraphic study of the Huatugou section, northwestern Qaidam basin, reveals that this section spans the period from ?30 to ?11 Ma. Magnetostratigraphic and sedimentological studies indicate that the accumulation rate abruptly increased near ?15 Ma. The acceleration in sedimentation rate suggests enhanced tectonic deformation in the Qaidam basin since 15 Ma that may have begun simultaneously with accelerated deformation along the Altyn Tagh, Kunlun, and Haiyuan faults, which contributed to the growth history of the Qaidam basin and its surroundings since ?15 Ma.

  16. Early evolution of the southern margin of the Neuquén Basin, Argentina: Tectono-stratigraphic implications for rift evolution and exploration of hydrocarbon plays

    Science.gov (United States)

    D'Elia, Leandro; Bilmes, Andrés; Franzese, Juan R.; Veiga, Gonzalo D.; Hernández, Mariano; Muravchik, Martín

    2015-12-01

    Long-lived rift basins are characterized by a complex structural and tectonic evolution. They present significant lateral and vertical stratigraphic variations that determine diverse basin-patterns at different timing, scale and location. These issues cause difficulties to establish facies models, correlations and stratal stacking patterns of the fault-related stratigraphy, specially when exploration of hydrocarbon plays proceeds on the subsurface of a basin. The present case study corresponds to the rift-successions of the Neuquén Basin. This basin formed in response to continental extension that took place at the western margin of Gondwana during the Late Triassic-Early Jurassic. A tectono-stratigraphic analysis of the initial successions of the southern part of the Neuquén Basin was carried out. Three syn-rift sequences were determined. These syn-rift sequences were located in different extensional depocentres during the rifting phases. The specific periods of rifting show distinctly different structural and stratigraphic styles: from non-volcanic to volcanic successions and/or from continental to marine sedimentation. The results were compared with surface and subsurface interpretations performed for other depocentres of the basin, devising an integrated rifting scheme for the whole basin. The more accepted tectono-stratigraphic scheme that assumes the deposits of the first marine transgression (Cuyo Cycle) as indicative of the onset of a post-rift phase is reconsidered. In the southern part of the basin, the marine deposits (lower Cuyo Cycle) were integrated into the syn-rift phase, implying the existence of different tectonic signatures for Cuyo Cycle along the basin. The rift climax becomes younger from north to south along the basin. The post-rift initiation followed the diachronic ending of the main syn-rift phase throughout the Neuquén Basin. Thus, initiation of the post-rift stage started in the north and proceeded towards the south, constituting a diachronous post-rift event. This arrangement implies that the lower part of Cuyo Cycle, traditionally related to regional thermal subsidence, may be deposited during either mechanical subsidence or thermal subsidence according to its position within the basin.

  17. Gas desorption and adsorption isotherm studies of coals in the Powder River basin, Wyoming and adjacent basins in Wyoming and North Dakota

    Science.gov (United States)

    Stricker, Gary D.; Flores, Romeo M.; McGarry, Dwain E.; Stillwell, Dean P.; Hoppe, Daniel J.; Stillwell, Cathy R.; Ochs, Alan M.; Ellis, Margaret S.; Osvald, Karl S.; Taylor, Sharon L.; Thorvaldson, Marjorie C.; Trippi, Michael H.; Grose, Sherry D.; Crockett, Fred J.; Shariff, Asghar J.

    2006-01-01

    The U.S. Geological Survey (USGS), in cooperation with the State Office, Reservoir Management Group (RMG), of the Bureau of Land Management (BLM) in Casper (Wyoming), investigated the coalbed methane resources (CBM) in the Powder River Basin, Wyoming and Montana, from 1999 to the present. Beginning in late 1999, the study also included the Williston Basin in Montana and North and South Dakota and Green River Basin and Big Horn Basin in Wyoming. The rapid development of CBM (referred to as coalbed natural gas by the BLM) during the early 1990s, and the lack of sufficient data for the BLM to fully assess and manage the resource in the Powder River Basin, in particular, gave impetus to the cooperative program. An integral part of the joint USGS-BLM project was the participation of 25 gas operators that entered individually into confidential agreements with the USGS, and whose cooperation was essential to the study. The arrangements were for the gas operators to drill and core coal-bed reservoirs at their cost, and for the USGS and BLM personnel to then desorb, analyze, and interpret the coal data with joint funding by the two agencies. Upon completion of analyses by the USGS, the data were to be shared with both the BLM and the gas operator that supplied the core, and then to be released or published 1 yr after the report was submitted to the operator.

  18. Hydrogeologic Characteristics of the St. Croix River Basin, Minnesota and Wisconsin: Implications for the Susceptibility of Ground Water to Potential Contamination

    Science.gov (United States)

    Juckem, Paul F.

    2007-01-01

    Population growth in the St. Croix River Basin in Minnesota and Wisconsin has intensified concerns of county resource managers and the National Park Service, which is charged with protecting the St. Croix National Scenic Riverway, about the potential for ground-water contamination in the basin. This report describes a previously developed method that was adapted to illustrate potential ground-water-contamination susceptibility in the St. Croix River Basin. The report also gives an estimate of ground-water-residence time and surface-water/ground-water interaction as related to natural attenuation and movement of contaminants in five tributary basins. A ground-water-contamination-susceptibility map was adapted from a state-wide map of Wisconsin to the St. Croix River Basin by use of well-driller construction records and regional maps of aquifer properties in Minnesota and Wisconsin. Measures of various subsurface properties were combined to generate a spatial index of susceptibility. The subjective index method developed for the State of Wisconsin by Schmidt (1987) was not derived from analyses of water-quality data or physical processes. Nonetheless, it was adapted for this report to furnish a seamless map across state boundaries that would be familiar to many resource managers. Following this method, areas most susceptible to contamination appear to have coarse-grained sediments (sands or gravels) and shallow water tables or are underlain by carbonate-bedrock aquifers. The least susceptible areas appear to have fine-grained sediments and deep water tables. If an aquifer becomes contaminated, the ground-water-residence time can affect potential natural attenuation along the ground-water-flow path. Mean basin ground-water-residence times were computed for the Apple, Kettle, Kinnickinnic, Snake and Sunrise River Basins, which are tributary basins to the St. Croix Basin, by use of average aquifer properties of saturated thickness, porosity, and recharge rates. The Apple River Basin had the shortest mean ground-water-residence times (20-120 years), owing largely to the moderate saturated thickness and high recharge rate in the basin. The Kinnickinnic and Sunrise River Basins had the longest mean residence times (60-350 and 70-390 years, respectively) chiefly because of the relatively large saturated thickness of the basins. Owing to limitations of the residence-time calculations, actual ground-water-residence times will vary around the mean values within each basin and may range from days or weeks in karst carbonate aquifers to millennia in deep confined sandstone aquifers. Areas of relatively short residence time (less than the median residence time in each basin) were identified by use of ground-water-flow models for each of the five tributary basins. Results of simulations show that these areas, in which contaminants may have relatively less time for natural attenuation along the short flow paths, generally occur near streams and rivers where ground water discharges to the surface. Finally, the ground-water-flow models were used to simulate ground-water/surface-water interaction in the five tributary basins. Results of simulations show that some lakes and reservoirs leak surface water into the ground-water-flow system on their downgradient side, where the surface-water outflow has been restricted by a dam or a naturally constricted outlet. These locations are noteworthy because contaminated surface waters could potentially enter the ground-water-flow system at these locations.

  19. Role of sea-level change in deep water deposition along a carbonate shelf margin, Early and Middle Permian, Delaware Basin: implications for reservoir characterization

    Science.gov (United States)

    Li, Shunli; Yu, Xinghe; Li, Shengli; Giles, Katherine A.

    2015-04-01

    The architecture and sedimentary characteristics of deep water deposition can reflect influences of sea-level change on depositional processes on the shelf edge, slope, and basin floor. Outcrops of the northern slope and basin floor of the Delaware Basin in west Texas are progressively exposed due to canyon incision and road cutting. The outcrops in the Delaware Basin were measured to characterize gravity flow deposits in deep water of the basin. Subsurface data from the East Ford and Red Tank fields in the central and northeastern Delaware Basin were used to study reservoir architectures and properties. Depositional models of deep water gravity flows at different stages of sea-level change were constructed on the basis of outcrop and subsurface data. In the falling-stage system tracts, sandy debris with collapses of reef carbonates are deposited on the slope, and high-density turbidites on the slope toe and basin floor. In the low-stand system tracts, deep water fans that consist of mixed sand/mud facies on the basin floor are comprised of high- to low-density turbidites. In the transgression and high-stand system tracts, channel-levee systems and elongate lobes of mud-rich calciturbidite deposits formed as a result of sea level rise and scarcity of sandy sediment supply. For the reservoir architecture, the fan-like debris and high-density turbidites show high net-to-gross ratio of 62 %, which indicates the sandiest reservoirs for hydrocarbon accumulation. Lobe-like deep water fans with net-to-gross ratio of 57 % facilitate the formation of high quality sandy reservoirs. The channel-levee systems with muddy calciturbidites have low net-to-gross ratio of 30 %.

  20. Late Aptian-Albian of the Vocontian Basin (SE-France) and Albian of NE-Texas: Biostratigraphic and paleoceanographic implications by planktic foraminifera faunas

    OpenAIRE

    Reichelt, Kerstin

    2005-01-01

    Planktic foraminifera fauna and carbon isotopes of the bulk rock have been investigated to compile a high resolution biostratigraphy for the Late Aptian to Late Albian in the Vocontian Basin (SE-France) and for the Middle and Late Albian in NE-Texas. A high resolution carbon isotope stratigraphy (CIS) has been established for the Albian of the Vocontian Basin, and partially correlated with sections in the eastern (ODP 547, Mazagan Plateau) and western (ODP 1052; Blake Nose Plateau) Atlantic a...

  1. Magnetic fabrics in the Jurassic-Cretaceous continental basins of the northern part of the Central High Atlas (Morocco): Geodynamic implications

    Science.gov (United States)

    Moussaid, B.; El Ouardi, H.; Casas-Sainz, A.; Villalaín, J. J.; Román-Berdiel, T.; Oliva-Urcia, B.; Soto, R.; Torres-López, S.

    2013-11-01

    The aim of this work is to study the Anisotropy of the Magnetic Susceptibility (AMS) in two Jurassic-Cretaceous synclines located in the northern border of the Central High Atlas (Morocco): the Aït Attab and Ouaouizaght basins. AMS is used in order to obtain the magnetic fabric and its relationship with the kinematic evolution of both basins. The tectonic evolution of the basins, still under discussion, is mostly considered as the result of inversion during Tertiary and perhaps since Bathonian, of extensional and/or strike-slip Jurassic basins. Both basins are filled with Upper Jurassic to Lower Cretaceous silts and sandstones, with less frequent marine marly limestones. The bulk magnetic susceptibility (km) generally shows higher values in the red facies (163.2 E-6 in AT and 168.6 E-6 in WZ) than in the yellowish marly limestones (97.88 E-6 in AT and 132 E-6 in WZ). Most sites show an oblate magnetic fabric. The rock magnetic analyses indicate that the main carrier of the magnetic susceptibility for the red facies is hematite, whereas in the yellowish facies there is a dominance of paramagnetic minerals. In both basins, the magnetic lineation (long axis of the ellipsoid, kmax axes) shows a predominant E-W direction. The overlapping of the stress fields during the Atlasic basins evolution, in both compressional and extensional regimes and hinder the straightforward interpretation of the magnetic fabrics. However, a coeval N-S compression during the times of sedimentation with an E-W transtension can explain the magnetic lineation found in many of the sites analyzed in the present work. There are also other less frequent directions of kmax axes (NE-SW and NW-SE) are interpreted as the result of local change of the stress field during the early extensional stage of basin formation.

  2. Discovering the Cubango-Okavango river basin. A geomorphological description of the Angolan rivers and its fish assemblages and the ecological implications of future human development

    OpenAIRE

    Preiswerk, Sebastian Benedikt Coimbra

    2013-01-01

    The years fly by but the African continet and its enourmos richness remains an undiscovered treasure. The Angolan province Cuando-Cubango includes one of the biggest watersheds of the African continent, the Cubango-Okavango river basin. One of the rivers where most parts remains untouched and in a pristine form. Ongoing water resources planning intends to regulate large parts of the basin and to intensify human uses. In order to better understand and to analize ecological respo...

  3. Assessment of undiscovered conventional oil and gas resources of the Western Canada Sedimentary Basin, Canada, 2012

    Science.gov (United States)

    Higley, Debra

    2013-01-01

    The U.S. Geological Survey recently completed a geoscience-based assessment of undiscovered oil and gas resources of provinces within the Western Canada Sedimentary Basin. The Western Canada Sedimentary Basin primarily comprises the (1) Alberta Basin Province of Alberta, eastern British Columbia, and the southwestern Northwest Territories; (2) the Williston Basin Province of Saskatchewan, southeastern Alberta, and southern Manitoba; and (3) the Rocky Mountain Deformed Belt Province of western Alberta and eastern British Columbia. This report is part of the U.S. Geological Survey World Petroleum Resources Project assessment of priority geologic provinces of the world. The assessment was based on geoscience elements that define a total petroleum system (TPS) and associated assessment unit(s). These elements include petroleum source rocks (geochemical properties and petroleum generation, migration, and accumulation), reservoir description (reservoir presence, type, and quality), and petroleum traps (trap and seal types, and timing of trap and seal formation relative to petroleum migration). Using this framework, the Elk Point-Woodbend Composite TPS, Exshaw-Fernie-Mannville Composite TPS, and Middle through Upper Cretaceous Composite TPS were defined, and four conventional assessment units within the total petroleum systems were quantitatively assessed for undiscovered resources in the Western Canada Sedimentary Basin.

  4. Provenance of the Lower Triassic Bunter Sandstone Formation: implications for distr ibution and architecture of aeolian versus alluvial-fluvial reservoir s in the Nor th German Basin

    DEFF Research Database (Denmark)

    Olivarius, Mette; Weibel, Rikke

    2015-01-01

    Zircon U–Pb geochronometry, heavy mineral analyses and conventional seismic reflection data were used to interpret the provenance of the Lower Triassic Bunter Sandstone Formation. The succession was sampled in five Danish wells in the northern part of the North German Basin. The zircon ages found in the Bunter Sandstone show that sediment supply was mainly derived from the Ringkøbing-Fyn High and the Variscan belt and not from the Fennoscandian Shield as previously believed. Seismic reflection data document that the Ringkøbing-Fyn High was a local barrier for sediment transport. Provenance analysis is an invaluable tool of correlation and subdivision of the Bunter Sandstone in this marginal basin setting. This is because the succession includes many hiatuses so the cyclo-, magneto-, and bio-stratigraphic frameworks established elsewhere in the basin cannot readily be applied here. Zircon ages in the Volpriehausen Member (lower Bunter Sandstone) indicate derivation from source areas located to the south of the North German Basin that are of late Neoproterozoic to Carboniferous age. The dominant age population with a peak age of 337 Ma corresponds to the culmination of Variscan high-grade metamorphism, whereas a secondary age population with a peak at 300 Ma matches the timing of volcanism and magmatism at the Carboniferous/Permian boundary in the northern Variscan belt. The Ringkøbing-Fyn High also supplied some sediment tothe Volpriehausen Member. The zircon ages obtained from the Solling Member (upper Bunter Sandstone) match basement ages from the Ringkøbing-Fyn High and show that sediment contributions came mainly from the north. The age distributions are dominated by Mesoproterozoic zircon grains with a Sveconorwegian metamorphic overprint. The heavy mineral assemblage of the Solling Member is uniform and has a high garnet content compared to the contemporaneous sediments in the southern part of the North German Basin. This finding confirms that a local source supplied most of the sediment in the northern part of the basin. The most promising reservoir in the basin area is the aeolian Volpriehausen Member since the sandstone constitutes a lateral continuous unit. This is because sediment from the Variscan belt was transported by wind activity across the North German Basin when it was dried out. The alluvial to ephemeral fluvial Solling Member may be a good reservoir in the platform areas and marginal basin areas, but the variable sand content makes it difficult to predict the reservoir quality.

  5. Seismic imaging of deep low-velocity zone beneath the Dead Sea basin and transform fault: Implications for strain localization and crustal rigidity

    Science.gov (United States)

    ten Brink, U.S.; Al-Zoubi, A. S.; Flores, C.H.; Rotstein, Y.; Qabbani, I.; Harder, S.H.; Keller, Gordon R.

    2006-01-01

    New seismic observations from the Dead Sea basin (DSB), a large pull-apart basin along the Dead Sea transform (DST) plate boundary, show a low velocity zone extending to a depth of 18 km under the basin. The lower crust and Moho are not perturbed. These observations are incompatible with the current view of mid-crustal strength at low temperatures and with support of the basin's negative load by a rigid elastic plate. Strain softening in the middle crust is invoked to explain the isostatic compensation and the rapid subsidence of the basin during the Pleistocene. Whether the deformation is influenced by the presence of fluids and by a long history of seismic activity on the DST, and what the exact softening mechanism is, remain open questions. The uplift surrounding the DST also appears to be an upper crustal phenomenon but its relationship to a mid-crustal strength minimum is less clear. The shear deformation associated with the transform plate boundary motion appears, on the other hand, to cut throughout the entire crust. Copyright 2006 by the American Geophysical Union.

  6. Basin structure beneath the Santa Rosa Plain, Northern California: Implications for damage caused by the 1969 Santa Rosa and 1906 San Francisco earthquakes

    Science.gov (United States)

    McPhee, D.K.; Langenheim, V.E.; Hartzell, S.; McLaughlin, R.J.; Aagaard, B.T.; Jachens, R.C.; McCabe, C.

    2007-01-01

    Regional gravity data in the northern San Francisco Bay region reflect a complex basin configuration beneath the Santa Rosa plain that likely contributed to the significant damage to the city of Santa Rosa caused by the 1969 M 5.6, 5.7 Santa Rosa earthquakes and the 1906 M 7.9 San Francisco earthquake. Inversion of these data indicates that the Santa Rosa plain is underlain by two sedimentary basins about 2 km deep separated by the Trenton Ridge, a shallow west-northwest-striking bedrock ridge west of Santa Rosa. The city of Santa Rosa is situated above the 2-km-wide protruding northeast corner of the southern basin where damage from both the 1969 and 1906 earthquakes was concentrated. Ground-motion simulations of the 1969 and 1906 earthquakes, two events with opposing azimuths, using the gravity-defined basin surface, show enhanced ground motions along the northeastern edge of this corner, suggesting that basin-edge effects contributed to the concentration of shaking damage in this area in the past and may also contribute to strong shaking during future earthquakes.

  7. Seismic sequence stratigraphy of a foreland unit inthe Magallanes-Austral Basin, Dorado Riquelme Block, Chile: Implications for deep-marine reservoirs

    Scientific Electronic Library Online (English)

    Rocío E, Gallardo.

    2014-06-01

    Full Text Available This contribution presents geological data that provides a sequence-stratigraphic-based exploration model for Oligocene units in the central Magallanes-Austral Foreland Basin, and identifies the related sedimentary deposits that constitute basin-floor fan reservoirs. The study area is located in the [...] Magallanes Region, Chile, and it was discovered in 2009-2010 by the joint venture of the National Oil Company of Chile and Methanex group at Dorado Riquelme Block. Seismic stratigraphic analysis of the Magallanes-Austral Foreland Basin enabled the definition of four evolutionary stages using 3D seismic information from a 91.6 km long section, as well as lithostratigraphic and biostratigraphic records and wireline logs. The clinoforms observed in the Foreland III stage of the Magallanes-Austral Foreland Basin are the focus of this study. Six seismic units (SU-1 to SU-6) and twenty-five depositional sequences were identified there, based on temporal affinity and genetic mechanisms. The youngest four seismic units comprise alternating forestepping and downstepping prograding patterns, while the fifth seismic unit is characterized by a backstepping pattern, which is followed by a sixth seismic unit in which forestepping patterns are again developed. The most important reservoirs were identified in seismic unit SU-2, and they are associated with sandstone-prone deposits accumulated in basin-floor fans. Their development is associated in this contribution with periods of relative sea-level fall during forced regressions.

  8. Hydrological implications of {sup 234}U/{sup 238}U disequilibria observed along pressure dissolution structures within deep mesozoic limestone formations of the Eastern Paris basin

    Energy Technology Data Exchange (ETDEWEB)

    Deschamps, P.; Hillaire-Marcel, C.; Ghaleb, B. [Geotop-Uqam-McGill, Montreal (Canada); Deschamps, P.; Michelot, J.L. [Paris-11 Univ., FRE CNRS-UPS Orsay Terre, 91 - Orsay (France); Doucelance, R. [Universite Blaise Pascal, Clermont-Ferrand-2, Lab. ' Magmas et Volcans' , 63 - Aubiere (France); Buschaert, St. [Agence Nationale pour la Gestion des Dechets Radioactifs (ANDRA), 92 - Chatenay Malabry (France)

    2004-07-01

    This study is part of geological investigations conducted by ANDRA (French agency for nuclear waste management) around the Underground Research Laboratory excavated in a clay layer of the Eastern part of the sedimentary Paris Basin, France. The safety of such nuclear waste disposal relies on a multi-barrier approach that must prevent radionuclide migration from the disposal site to the biosphere. Fluid circulations constitute a critical parameter for the confining capacities of the system, since they are the most effective and fastest mechanism by which radionuclides can reach the biosphere. Consequently, knowledge of the past and present hydrological and geochemical regimes within the geological system is fundamental to making predictions of the behavior of radionuclides when they are released from the 'near field'. In a previous study, we reported systematic ({sup 234}U/{sup 238}U) disequilibria only in the vicinity of pressure dissolution structures -stylolites- localized in the Bathonian and Oxfordian limestones that under- and overly the target argilite unit. This finding provides in situ indications of the confining capacities of these deep formations and highlights a mobility of uranium within the carbonated units. This is a major and surprising result since these deep, low-permeability, compact formations are generally supposed to behave as a chemically stable system. More precisely, these results highlight an active re-localization of uranium in the last 1-2 Ma within the stylolitized zones of the Bathonian and Oxfordian formations. The question arises now of the driving phenomena responsible for the 'recent' re-localization of uranium and of their hydrological implications. Uranium fractionation and re-localization can be, indirectly or directly, related to the phenomenon of stylolitization. The stylolitic discontinuities present high chemical and mineralogical heterogeneities due to the accumulation of non-soluble minerals. The ({sup 234}U/{sup 238}U) disequilibria observed in these zones may highlight geochemical transfers due to the high gradient of uranium concentration between the detrital material within the seams and the embedding carbonate matrix. Other possible explanation is an active stylolitization or reactivation of this phenomenon in the recent time (in the last 1-2 Ma). Pressure dissolution process, particularly in horizontal plane, may result from overburden. One cannot therefore exclude that the current gravitational loading causes stylolitization within the most stressed domains of the limestones. Pressure dissolution goes with mass transfer through an aqueous phase, either by diffusion or bulk flow, of the material dissolved within stylolitic seams. Therefore, uranium associated with the dissolved carbonate material was redistributed in the surrounding carbonate matrix together with other dissolution products (major or trace elements). This may lead to precipitation of secondary carbonate cement within pore spaces of less stressed zones. If this case arises, this would have important hydrological consequences since stylolitization goes with reprecipitation of secondary carbonate phases within pore spaces of the host matrix, thereby reducing the porosity and permeability of the limestone formations. In both cases discussed above, the ({sup 234}U/{sup 238}U) disequilibria observed within stylolitic zones would characterize late epi-diagenetic phenomena that do not involve massive transport of uranium into or out of the system and open-system behavior at large scale. Water/rock interactions induced by the physical and chemical perturbation associated with flowing fluids are often put forward to explain U-series disequilibria observed on rocks in the upper lithosphere. In the present case, although this assumption cannot be totally ruled out, there is no other clear geochemical evidence for such a phenomenon. Moreover, from an hydrologic point of view, these limestones have also very low porosities and permeabilities. In this second hypothesis, pressure dissolution surfaces co

  9. Hydrological implications of 234U/238U disequilibria observed along pressure dissolution structures within deep mesozoic limestone formations of the Eastern Paris basin

    International Nuclear Information System (INIS)

    This study is part of geological investigations conducted by ANDRA (French agency for nuclear waste management) around the Underground Research Laboratory excavated in a clay layer of the Eastern part of the sedimentary Paris Basin, France. The safety of such nuclear waste disposal relies on a multi-barrier approach that must prevent radionuclide migration from the disposal site to the biosphere. Fluid circulations constitute a critical parameter for the confining capacities of the system, since they are the most effective and fastest mechanism by which radionuclides can reach the biosphere. Consequently, knowledge of the past and present hydrological and geochemical regimes within the geological system is fundamental to making predictions of the behavior of radionuclides when they are released from the 'near field'. In a previous study, we reported systematic (234U/238U) disequilibria only in the vicinity of pressure dissolution structures -stylolites- localized in the Bathonian and Oxfordian limestones that under- and overly the target argilite unit. This finding provides in situ indications of the confining capacities of these deep formations and highlights a mobility of uranium within the carbonated units. This is a major and surprising result since these deep, low-permeability, compact formations are generally supposed to behave as a chemically stable system. More precisely, these results highlight an active re-localization of uranium in the last 1-2 Ma within the stylolitized zones of the Bathonian and Oxfordian formations. The question arises now of the driving phenomena responsible for the 'recent' re-localization of uranium and of their hydrological implications. Uranium fractionation and re-localization can be, indirectly or directly, related to the phenomenon of stylolitization. The stylolitic discontinuities present high chemical and mineralogical heterogeneities due to the accumulation of non-soluble minerals. The (234U/238U) disequilibria observed in these zones may highlight geochemical transfers due to the high gradient of uranium concentration between the detrital material within the seams and the embedding carbonate matrix. Other possible explanation is an active stylolitization or reactivation of this phenomenon in the recent time (in the last 1-2 Ma). Pressure dissolution process, particularly in horizontal plane, may result from overburden. One cannot therefore exclude that the current gravitational loading causes stylolitization within the most stressed domains of the limestones. Pressure dissolution goes with mass transfer through an aqueous phase, either by diffusion or bulk flow, of the material dissolved within stylolitic seams. Therefore, uranium associated with the dissolved carbonate material was redistributed in the surrounding carbonate matrix together with other dissolution products (major or trace elements). This may lead to precipitation of secondary carbonate cement within pore spaces of less stressed zones. If this case arises, this would have important hydrological consequences since stylolitization goes with reprecipitation of secondary carbonate phases within pore spaces of the host matrix, thereby reducing the porosity and permeability of the limestone formations. In both cases discussed above, the (234U/238U) disequilibria observed within stylolitic zones would characterize late epi-diagenetic phenomena that do not involve massive transport of uranium into or out of the system and open-system behavior at large scale. Water/rock interactions induced by the physical and chemical perturbation associated with flowing fluids are often put forward to explain U-series disequilibria observed on rocks in the upper lithosphere. In the present case, although this assumption cannot be totally ruled out, there is no other clear geochemical evidence for such a phenomenon. Moreover, from an hydrologic point of view, these limestones have also very low porosities and permeabilities. In this second hypothesis, pressure dissolution surfaces could act as preferential conduits for flowing fluids. Flu

  10. Origin of ash in the Central Indian Ocean Basin and its implication for the volume estimate of the 74,000 year BP Youngest Toba eruption

    Digital Repository Service at National Institute of Oceanography (India)

    Pattan, J.N.; Pearce, N.J.G.; Banakar, V.K.; Parthiban, G.

    .86) 4.22 (0 .33) ? 4.94 N 91 274 72 53 16 1, Central Indian Ocean Basin 7 (present study); 2, YTT from Sum a tra, Malaysia, Bay of Bengal and India 10 ; 3, YTT from the Indian subcont i- nent 15 ; 4, YTT from....4 7.5 6.6 5.9 6.9 6.9 5.1 5.8 6.5 1, Central Indian Ocean Basin (pr esent study, n = 8); 2, YTT from Sumatra, Malaysia, ODP site 758, Bay of Bengal and India 10 ( n...

  11. Seismic stratigraphic analysis of the Cenozoic sediments in the NW Faroe Shetland BasinImplications for inherited structural control of sediment distribution

    DEFF Research Database (Denmark)

    Ólavsdóttir, Jana; Andersen, Morten Sparre

    2013-01-01

    The post-basalt strata in the Faroese area have been investigated based on interpretation of 2D and 3D reflection seismic data. The post-basalt package is divided into 5 units which have led to the constructions of 6 structural maps and 5 thickness maps. Within the 5 units 12 prograding sediment bodies have been identified. Based on the interpretation it is possible to obtain an overview during time of the location of depocentres and direction of prograding units. Within Eocene time the depocentre was placed in the central part of the basin and the sediment influx was mostly from south and southwest. During Oligocene–Pliocene time the sediment influx was from north and northwest and the depocentre had moved in a westward direction closer to the Faroe Platform area. Emplacement of the Cenozoic sediments in the Faroese sector of the Faroe-Shetland Basin is controlled by thermal subsidence of the basin, and local uplift of sediment source areas. Reactivation of older, Paleozoic and Mesozoic, structural elements seem to control the sediment path way and restrict the depositional areas. Various structural elements being re-activated at different times caused considerable structural complexity. Understanding the older, structural elements and their control on sedimentation is a potential tool for understanding deviations from “normal” thermal subsidence and for predicting the prospectivity in the post-basalt succession in the Faroe-Shetland Basin.

  12. A high-resolution carbon-isotope record of the Turonian stage correlated to a siliciclastic basin fill: Implications for mid-Cretaceous sea-level change.

    Czech Academy of Sciences Publication Activity Database

    Uli?ný, David; Jarvis, I.; Gröcke, D. R.; ?ech, S.; Laurin, Ji?í; Olde, K.; Trabucho-Alexandre, J.; Švábenická, L.; Pedentchouk, N.

    2014-01-01

    Ro?. 405, July (2014), s. 42-58. ISSN 0031-0182 R&D Projects: GA ?R GAP210/10/1991; GA MŠk LA08036 Institutional support: RVO:67985530 Keywords : eustasy * carbon isotopes * Bohemian Cretaceous Basin * Turonian * greenhouse climate * sequence stratigraphy Subject RIV: DB - Geology ; Mineralogy Impact factor: 2.339, year: 2014

  13. Geochemistry of basal Cambrian black shales and cherts from the Northern Tarim Basin, Northwest China: Implications for depositional setting and tectonic history

    Science.gov (United States)

    Yu, Bingsong; Dong, Hailiang; Widom, Elisabeth; Chen, Jianqiang; Lin, Changsong

    2009-03-01

    Black shales and thin-bedded cherts in the basal Cambrian are widespread worldwide and they carry important information on the formation of sedimentary basins and on the tectonic history. We studied the geochemical signatures of the early Cambrian black shales and bedded cherts from the Northern Tarim Basin, China, with the objectives of understanding the depositional setting of these rocks and inferring the tectonic history in the region. Twenty two black shales, ten cherts, and two nodular phosphorites were collected from two outcrops at Xiaoerbulake and Sugaitebulake in the Northern Tarim Basin, spanning vertical sections of 8.8 and 7.5 m, respectively. A suite of techniques, including field investigations, X-ray diffraction, electron microscopy, trace element, rare earth element (REE), and isotope geochemistry, were employed to characterize the geochemical signatures of these rocks. Field evidence indicates that the black shales and bedded cherts are over- and underlain by dolomites, suggesting a shallow marine depositional environment. Mineralogical and trace element data suggest that the Tarim black shales and cherts were deposited in a suboxic continental shelf environment, and hydrothermal activity may have extracted certain trace elements from mafic continental crust and concentrated them in the sedimentary basin. REE characteristics for the cherts are very similar to those that are known to be deposited in pelagic ocean floor settings, suggesting that the hydrothermal fluids may be derived from the infant southern Tianshan Ocean in the north of the Tarim Basin. Os isotope signatures at the time of deposition ( 187Os/ 188Os i = 1.1-2.7) are typical of crustal signatures, and the radiogenic Os isotope signatures rule out the mantle as a possible source of Os and other metals. A positive correlation between 187Os/ 188Os and ?Nd is consistent with upper crust-derived basin sediments that contain a variable contribution of hydrothermal fluids possibly derived from ancient mafic continental crust. These trace element, REE, and isotope systematics collectively suggest that incorporation of hydrothermal fluids derived from ancient, mafic continental crust combined with deposition in relatively reducing conditions may have controlled the chemical and isotopic compositions of these rocks. We infer that the hydrothermal fluid was carried to the continental shelf by upwelling during the initial stages of formation of the southern Tianshan Ocean, where the fluid interacted with thinned, mafic crustal basement lithologies and was subsequently incorporated into the black shales and bedded cherts in the Northern Tarim Basin. This study provides important geochemical evidence for the creation of the Tianshan Ocean, which is a result of break-up of the Rodinia Supercontinent during the early Cambrian.

  14. Coarse-grained sediment delivery and distribution in the Holocene Santa Monica Basin, California: Implications for evaluating source-to-sink flux at millennial time scales

    Science.gov (United States)

    Romans, B.W.; Normark, W.R.; McGann, M.M.; Covault, J.A.; Graham, S.A.

    2009-01-01

    Utilizing accumulations of coarse-grained terrigenous sediment from deep-marine basins to evaluate the relative contributions of and history of controls on sediment flux through a source-to-sink system has been difficult as a result of limited knowledge of event timing. In this study, six new radiocarbon (14C) dates are integrated with five previously published dates that have been recalibrated from a 12.5-m-thick turbidite section from Ocean Drilling Program (ODP) Site 1015 in Santa Monica Basin, offshore California. This borehole is tied to high-resolution seismic-reflection profiles that cover an 1100 km2 area of the middle and lower Hueneme submarine fan and most of the basin plain. The resulting stratigraphic framework provides the highest temporal resolution for a thick-bedded Holocene turbidite succession to date, permitting an evaluation of source-to-sink controls at millennial (1000 yr) scales. The depositional history from 7 ka to present indicates that the recurrence interval for large turbidity-current events is relatively constant (300-360 yr), but the volume of sediment deposited on the fan and in the basin plain has increased by a factor of 2 over this period. Moreover, the amount of sand per event on the basin plain during the same interval has increased by a factor of 7. Maps of sediment distribution derived from correlation of seismic-reflection profiles indicate that this trend cannot be attributed exclusively to autogenic processes (e.g., progradation of depocenters). The observed variability in sediment accumulation rates is thus largely controlled by allogenic factors, including: (1) increased discharge of Santa Clara River as a result of increased magnitude and frequency of El Ni??o-Southern Oscillation (ENSO) events from ca. 2 ka to present, (2) an apparent change in routing of coarse-grained sediment within the staging area at ca. 3 ka (i.e., from direct river input to indirect, littoral cell input into Hueneme submarine canyon), and (3) decreasing rates of sea-level rise (i.e., rate of rise slowed considerably by ca. 3 ka). The Holocene history of the Santa Clara River-Santa Monica Basin source-to-sink system demonstrates the ways in which varying sediment flux and changes in dispersal pathways affect the basinal stratigraphic record. ?? 2009 Geological Society of America.

  15. Abundance of CO2-rich fluid inclusions in a sedimentary basin-hosted Cu deposit at Jinman, Yunnan, China: implications for mineralization environment and classification of the deposit

    Science.gov (United States)

    Chi, Guoxiang; Xue, Chunji

    2011-04-01

    The Jinman Cu deposit is hosted in sandstones and slates of the Jurassic Huakaizuo Formation in the Mesozoic to Cenozoic Lanping basin in western Yunnan, China. Despite the fact that Cu mineralization occurs mainly in quartz-carbonate veins controlled by faults and fractures, the Jinman deposit was classified as a sediment-hosted stratiform Cu deposit, mainly because it is hosted in a sedimentary basin characterized by abundant red beds with many stratiform Cu deposits. A detailed petrographic and microthermometric study of fluid inclusions from the Jinman deposit reveals the presence of abundant CO2-rich fluid inclusions, together with aqueous inclusions. The CO2-rich inclusions have CO2 melting temperatures mainly from -58.0°C to -56.6°C, homogenization temperatures of the carbonic phase (mostly into the liquid phase) mainly between 22°C and 30°C, clathrate melting temperatures from 1.8°C to 9.2°C, with corresponding salinities from 1.6 to 13.4 wt.% NaCl equivalent, and total homogenization temperatures from 226°C to 330°C. The aqueous inclusions have first melting temperatures from -60°C to -52°C, ice melting temperatures from -41.4°C to -2.3°C, with salinities from 3.9 to 29.0 wt.% NaCl equivalent, and total homogenization temperatures mainly from 140°C to 250°C. These fluid inclusion characteristics are comparable to those of orogenic or magmatic mineralization systems and are uncharacteristic of basinal mineralization systems, suggesting that it is inappropriate to classify the Jinman deposit as a sediment-hosted stratiform Cu deposit. The results of this study, together with geochemical data reported previously, suggest that the Jinman deposit formed in a hydrothermal system that involved both extra-basinal, deeply sourced CO2-rich fluid and basinal, aqueous fluid.

  16. Cenozoic evolution of the Pamir plateau recorded in surrounding basins, implications on Asian climate, land-sea distribution and biotic crises

    Science.gov (United States)

    Dupont Nivet, G.; Yang, W.; Blayney, T.; Bougeois, L.; Manceau, C.; Najman, Y.; Proust, J. N.; Guo, Z.; Grothe, A.; Mandic, O.; Fioroni, C.

    2014-12-01

    The Cenozoic Pamir orogen formed in response to the India-Asia collision. Existing datasets shows that the range grew since ca. 25 Ma, however the early Cenozoic history remains unconstrained. In that period, global climate changed from greenhouse to icehouse, the proto-Paratethys sea retreated out of Asia and continental aridification as well as monsoons established over Asia. These environmental changes are held responsible for major floral and faunal crises. However, the causal relationships between these events remains to be established because of the lack of accurate age constraints on their geological records. Here, we provide well-dated stratigraphic records using magneto- and bio-stratigraphy from the basins surrounding the Pamir. Southeast of the Pamir, along the Kunlun Shan into the southwestern Tarim Basin, Eocene marine deposits are continuously overlain by 41 to 15 Ma continental redbeds themselves overlain by conglomerates in a classic foreland sequence with upward increasing grain-size, accumulation rates and provenance proximity. However, North of the Pamir along the southwestern Tian Shan and West of the Pamir into the Afghan-Tadjik Basin, the entire Oligocene period appears to be missing from the record between the last marine and the first continental sediments dated to the Early Miocene. This supports a simple model in response to initial Eocene Pamir indentation with foreland basin activation in the Southeast related to the Kunlun Shan northward thrusting, followed much later by early Miocene activation of the northern foreland basin related to the southwestern Tian Shan overthrusting. The coeval activation of a lithospheric right-lateral strike-slip system along the Pamir/Tarim boundary may have enabled to transfer deformation from the India-Asia collision to the Tian Shan and possibly the Talas Fergana fault. This simple model suggests the following two-stage paleoenvironmental evolution: (1) Late Eocene sea retreat linked to the onset of Pamir indentation in conjunction with global sea-level drop, decreasing CO2 levels and ice-cap formation and (2) Early Miocene Tarim Basin closure by northward indentation of the Pamir plateau. This two-stage evolution is consistent with the Eocene occurrence of continental aridity and Asian Monsoons and their Early Miocene intensification.

  17. Chronology of deformation and analogue modelling of the Plio-Pleistocene ‘Tiber Basin’: implications for the evolution of the Northern Apennines (Italy)

    Science.gov (United States)

    Bonini, Marco

    1998-02-01

    The Late Miocene-Quaternary hinterland basins located in the western sector of the Northern Appennines have been considered either as the surficial effect of the 'back-arc' extension related to the Tyrrhenian basin opening or related to late orogenic gravity spreading. Conversely, some authors recently suggested that they formed in a compressional regime and underwent a complex tectonic history. In this frame, the controversial origin of these hinterland basins is the subject of this paper. A structural study of the Plio-Pleistocene continental Tiber Basin (TB), one of the most important ones, has been carried out allowing to establish the role of lateral compressional and extensional deformations, both of which have been affecting the continental deposits during basin evolution. On the basis of field mapping and structural analysis, the development during Early-Middle Pliocene of the three main branches constituting the TB has been referred to a compressive regime related to the emplacement of a crustal thrust. The area was only later, during the Early Pleistocene, affected by extension characterised by NW-SE-trending normal faults as well as fault-controlled basins. These structures, in fact, obliquely cross-cut the NNW-trending older TB branches. The area was further affected by a NE-oriented shortening phase at the boundary between Early and Middle Pleistocene, which produced the partial inversion of the southwestern TB branch (Deruta-Terni Sector). The Pleistocene tectonic evolution of this sector has been also investigated by means of analogue modelling experiments, whose results support the hypothesised tectonic evolution. A succession of stress fields ranging from TB development up to Middle-Late Pleistocene has been reconstructed; they are characterised by a NE- to ENE-trending direction of compression or extension, and the variation through time of the stress field led to the reactivation of suitably oriented pre-existing structures. The proposed tectonic evolution of the TB indicates a rejuvenating of thrust activity in the study area as well as a retard of normal faulting with respect to the hypotheses proposed by previous authors.

  18. Palynology of Lower Palaeogene (Thanetian-Ypresian) coastal deposits from the Barmer Basin (Akli Formation, Western Rajasthan, India): palaeoenvironmental and palaeoclimatic implications

    Energy Technology Data Exchange (ETDEWEB)

    Tripathi, S.K.M.; Kumar, M.; Srivastava, D. [Birbal Sahni Instititue of Paleobotany, Lucknow (India)

    2009-03-15

    The 32-m thick sedimentary succession of the Paleocene-Eocene Akli Formation (Barmer basin, Rajasthan, India), which is exposed in an open-cast lignite mine, interbed several lignite seams that alternate with fossiliferous carbonaceous clays, green clays and widespread siderite bands and chert nodules. The palynofloral assemblages consist of spore, pollen and marine dinoflagellate cysts that indicate a Thanetian to Ypresian age. The assemblage is dominated by angiospermic pollen and specimens showing affinity with the mangrove Palm Nypa are also very abundant. The Nypa-like pollen specimens exhibit a wide range of morphological variation, some of the recorded morphotypes being restricted to this Indian basin. Preponderance of these pollen taxa indicates that the sediments were deposited in a coastal swamp surrounded by thick, Nypa-dominated mangrove vegetation. The dispersed organic matter separated from macerated residues indicates the dominance of anoxic conditions throughout the succession, although a gradual transition to oxic conditions is recorded in the upper part.

  19. Buried paleo-sedimentary basins in the north-eastern Black Sea-Azov Sea area and tectonic implications (DOBRE-2)

    Science.gov (United States)

    Starostenko, Vitaly; Stephenson, Randell; Janik, Tomasz; Tolkunov, Anatoly

    2014-05-01

    A number of independent but inter-related projects carried out under the auspices of various national and international programmes in Ukraine including DARIUS were aimed at imaging the upper lithosphere, crustal and sedimentary basin architecture in the north-eastern Black Sea, southern Crimea and Kerch peninsulas and the Azov Sea. This region marks the transition from relatively undisturbed Precambrian European cratonic crust and lithosphere north of the Azov Sea to areas of significant Phanerozoic tectonics and basin development, in both extensional as well as compressional environments, to the south, including the eastern Black Sea rift, which is the main sedimentary basin of the study area. The wide-angle reflection and refraction (WARR) profile DOBRE-2, a Ukrainian national project with international participation (see below), overlapping some 115 km of the southern end of the DOBREfraction'99 profile (that crosses the intracratonic Donbas Foldbelt) in the north and running to the eastern Black Sea basin in the south, utilised on- and offshore recording and energy sources. It maps crustal velocity structure across the craton margin and documents, among other things, that the Moho deepens from 40 km to ~47 km to the southwest below the Azov Sea and Crimean-Caucasus deformed zone. A regional CDP seismic profile coincident with DOBRE-2, crossing the Azov Sea, Kerch Peninsula and the north-eastern Black Sea southwest to the Ukraine-Turkey border, acquired by Ukrgeofisika (the Ukrainian national geophysical company) reveals in its inferred structural relationships the ages of Cretaceous and younger extensional and subsequent basin inversion tectonic events as well as the 2D geometry of basement displacement associated with post mid-Eocene inversion. A direct comparison of the results of the WARR velocity model and the near-vertical reflection structural image has been made by converting the former into the time domain. The results dramatically demonstrate that there are major, rift-like, sedimentary basins underlying the area of the Azov Sea and the inverted north-eastern margin of the Black Sea. It can be speculated that one of these basins may represent the previously unknown western prolongation of the Jurassic-aged Greater Caucasus back-arc basin and that the other may be the legacy of earlier - Late Palaeozoic-Triassic - extensional tectonics in this area. Individuals (in alphabetical order) from each institution involved scientifically in DOBRE-2 (listed alphabetically according to country) include: H. Thybo (Department of Geography and Geology, University of Copenhagen, Denmark); A. Dannowski and E. Flüh (IFM-GEOMAR, Kiel, Germany); W. Czuba, A. Guterch and P. ?roda (Institute of Geophysics, Polish Academy of Sciences, Warsaw, Poland); M. Grad (Institute of Geophysics, University of Warsaw, Warsaw, Poland); D. Gryn, K. Kolomiyets, O. Legostaeva, D. Lysynchuk, V. Omelchenko and O. Rusakov (Institute of Geophysics, National Academy of Sciences of Ukraine, Kyiv); M. Pobedash, N. Polyvach, G. Sydorenko and Z. Voitsytskyi (Ukrgeofisika, Kyiv, Ukraine); as well as the named co-authors of this presentation.

  20. Sedimentology and petrography of mass-emplaced limestone (Orahiri Limestone) on a late Oligocene shelf, western North Island, and tectonic implications for eastern margin development of Taranaki Basin

    International Nuclear Information System (INIS)

    The Te Kuiti Group in North Wanganui Basin, North Island, New Zealand, of Oligocene - earliest Miocene (Whaingaroan-Waitakian) age, is dominated by calcareous siltstone, calcareous sandstone, and skeletal limestone. Exposures in the southwestern corner of the basin at Awakino Tunnel are distinctive because, compared with elsewhere, the group is generally thicker (>300 m), has strong dips (25-45 degrees E), exhibits an up-section decrease in the amount of dip, and the capping Orahiri Limestone includes several thick (up to 3 m) mass-emplaced units containing a variety of 1-10 cm sized calcareous lithoclasts of older Te Kuiti Group rocks. Petrographic and ?18O and ?13C data suggest that the source deposits of these lithoclasts were cemented at relatively shallow subsurface burial depths (100-500 m) before their uplift and erosion. The lithoclasts so produced were rounded by abrasion in shoal water, often bored profusely by pholad bivalves, and sometimes encrusted by coralline algae, before being periodically mass-emplaced from west to east onto a shelf accumulating coeval Orahiri Limestone lithofacies now in the vicinity of Awakino Tunnel. Pressure-dissolution during subsequent burial provided the main source of calcite cement in the host Orahiri Limestone, mainly at moderate burial depths of 500-1000 m, according to ?18O data. The source region for the lithoclasts probably lay west of Awakino Tunnel and corresponds to the southern part of the basement Herangi High, which otherwise separates North Wanganui Basin from Taranaki Basin, but must have been submarine and accumulating Te Kuiti Group-equivalent calcareous facies during the early Oligocene (Early Whaingaroan, 36-32 Ma). Uplift of this depocentre was accompanied by synsedimentary eastward tilting of the Te Kuiti Group strata already deposited immediately east of Herangi High, contributing to the dips now measured at Awakino Tunnel. Inversion and tilting of the high began in the Late Whaingaroan, after 32 Ma ago, concomitant with the onset of rapid subsidence along eastern Taranaki Basin margin directly west of Herangi High. Uplift continued throughout the Duntroonian (28-24 Ma), when erosion and mass-emplacement supplied the abundant calcareous lithoclasts in the Orahiri Limestone, and into the Waitakian (24-22 Ma), when erosion possibly expanded onto parts of the shelf, stripping out sections of the overlying Otorohanga Limestone, the topmost formation in the group. The uplift and partial emergence of Herangi High is viewed as a topographic response to the initiation of basement over thrusting from the east along the Taranaki Fault Zone. The resultant loading evolved a carbonate foredeep in eastern Taranaki Basin during the Duntroonian-Waitakian. This late Oligocene phase of deformation developed in a mildly compressive regime, which corresponds to a time of proto-plate boundary development through New Zealand that preceded propagation of the continuous and more localised present plate boundary through the country at 22-23 Ma. The latter was marked in both North Wanganui Basin and Taranaki Basin by rejuvenated, more active basement overthrusting, the influx of copious amounts of terrigenous sediment, and the termination everywhere of extensive limestone and Te Kuiti Group deposition. (author). 38 refs., 11 figs., 4 tabs

  1. Provenance analysis of the Guaritas Group (RS conglomeratic sandstones: implications for the paleoclimate and paleogeography of the Eocambrian Central Camaquã sub-basin

    Directory of Open Access Journals (Sweden)

    Antonio Romalino Santos Fragoso-Cesar

    2013-06-01

    Full Text Available The Camaquã Supergroup, located in the central-south region of Rio Grande do Sul, Brazil, constitutes a rift-type post-orogenicsedimentary basin, whose deposition occurred in a continental environment between the Ediacaran and the Eocambrian.The upper succession of the Camaquã Supergroup is represented by the Guaritas Group, a unit formed by fluvial, eolian andalluvial fan deposits that keeps important records of the sedimentation right after the end of the neoproterozoic orogenesis thatgave rise to the Gondwana supercontinent. The objective of the present work was to apply sedimentary provenance analysis inconglomeratic arenites and conglomerates of the Guaritas Group, in order to explore the climatic and tectonic evolution historyof this unit. Based on the pebble compositional data, two main source areas were recognized for the deposits of this unit,a more distal one located to the north, related with a trunk river system parallel to the basin main axis, and a more proximalone located to the east, related to transversal fluvial systems and alluvial fans at the border of the basin. The comparison of theprovenance data with previous studies on facies and paleocurrents suggests that, during the entire evolution of the east borderof the basin, there was a same transversal fluvial system, whose catchment area suffered significative reductions due to thereactivation of the east border fault during the deposition of the Varzinha and Pedra Pintada Formations. The Serra do ApertadoFormation, the upper unit of Guaritas Group, shows a high correlation between the variation of quartzose and non quartzosepebbles composition, and it was attributed to a variation between more humid and more arid climatic conditions.

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

    OpenAIRE

    Zhan, Sheng; Yan CHEN; XU, Bei; Wang, Bo; Faure, Michel

    2007-01-01

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

  3. Rock magnetic properties and paleoenvironmental implications of an 8-Ma Late Cenozoic terrigenous succession from the northern Tian Shan foreland basin, northwestern China

    Science.gov (United States)

    Lu, Honghua; Zhang, Weiguo; Li, Youli; Dong, Chenyin; Zhang, Tianqi; Zhou, Zuyi; Zheng, Xiangmin

    2013-12-01

    In the northern Tian Shan foreland basin, northwestern China, the thick Cenozoic terrigenous succession is crucial for paleoclimate-environmental reconstruction of the Asian interior. Here we present a detailed rock magnetic investigation on 245 samples from the ~ 1200-m-thick Neogene Taxi He section with a magnetostratigraphic age span of ca. 8.0 to 2.0 Ma in the northern Tian Shan foreland basin. Our rock magnetic results indicate that the significant variations in composition, concentration and grain size of magnetic minerals occurred at ca. 6.0, 3.7 and 2.7 Ma. The comparable compositions of rare earth elements (REEs) throughout the Neogene Taxi He section suggest no significant modification of the source materials during the interval between ca. 8.0 and 2.0 Ma, and thus sediment provenance is not regarded as responsible for these observed variations in rock magnetic properties. Our further analyses show that the variations in magnetic properties of the Taxi He section are casually linked mainly with lithofacies transition due to range encroachment into foreland basin as well as climate aridification. Identified enhancement of aridification was chronologically constrained at ca. 6.0 and 2.7 Ma. Such climate events are important archives for reconstructing the Late Cenozoic paleoclimatic history of the Asian interior. Further comparison between different paleoclimate records clearly indicates that magnetic parameters such as S- 100mT are potentially effective proxy indices for paleoclimate-environmental reconstruction in the Tian Shan foreland basins and the nearby areas.

  4. The floating astronomical time scale for the terrestrial Late Cretaceous Qingshankou Formation from the Songliao Basin of Northeast China and its stratigraphic and paleoclimate implications

    Science.gov (United States)

    Wu, Huaichun; Zhang, Shihong; Jiang, Ganqing; Huang, Qinghua

    2009-02-01

    The Upper Cretaceous Qingshankou Formation (K 2qn) in the Songliao Basin (SLB) of Northeast China consists of up to 550 m thick, lacustrine mudstone and shale that constitute one of the most important source rocks of the Daqing oil field. A high-resolution cyclostratigraphic analysis of the natural gamma-ray logging from 10 wells of the Qingshankou Formation (K 2qn) reveals orbital cycles of precession (20 ka), obliquity (40 ka) and eccentricity (100 ka and 405 ka), providing strong evidence for astronomically driven climate changes in the Late Cretaceous terrestrial environments. Floating astronomical time scales (ATS) are established for all sections, which demonstrate variable durations of K 2qn across the basin (1.09 Ma-5.20 Ma) and strong diachroneity of the lacustrine strata. Four periods of high depositional rates can be identified in the central parts of the basin, possibly recording deposition during times of sustained wet climate and high chemical weathering. An ATS established from well M206 in the central depression zone of the basin, where the most complete and stable Milankovitch cycles are present, suggests that the maximum duration of the K 2qn is 5.20 Ma (from 94.27 Ma to 89.07 Ma; Late Cenomanian to Early Coniacian). The lacustrine anoxic event 1 (LAE1) at the Cenomanian-Turonian boundary lasted ~ 210-310 ka, during which the most prolific petroleum source rocks in SLB were deposited. The onset (~ 94.21-94.18 Ma) and duration (~ 210-310 Ka) of LAE1 in SLB are comparable to those of the oceanic anoxic event 2 (OAE2; onset at 94.21 Ma and duration of ~ 320-900 ka), suggesting that the same trigger mechanism, such as increased atmospheric CO 2 from large-scale igneous activity, may have initiated high primary productivity and organic carbon burial in both marine and terrestrial systems.

  5. Magnetic mineral study of Holocene marine sediments from the Alfonso Basin, Gulf of California - implications for depositional environment and sediment sources

    OpenAIRE

    L. Pérez Cruz; J. Urrutia Fucugauchi

    2009-01-01

    Results of a rock magnetic study of marine sediments from the Alfonso Basin, Bay of La Paz are used to investigate sediment sources and depositional environment in the southern Gulf of California during the Holocene. Radiocarbon dating provides stratigraphic control, with age for the core bottom sediments of 7597-7831 cal. yr B.P. Magnetic signal is dominated by fine-grained titanomagnetites, derived from the silicic volcanic units surrounding the Bay of La Paz. Magnetic mineralogy is relativ...

  6. Application of integrated vitrinite reflectance and FAMM analyses for thermal maturity assessment of the northeastern Malay Basin, offshore Vietnam: Implications for petroleum prospectivity evaluation

    DEFF Research Database (Denmark)

    Petersen, H. I.; Sherwood, N.; Mathiesen, A.; Fyhn, Michael Bryld Wessel; Dau, N. T.; Russell, N.; Bojesen-Koefoed, J. A.; Nielsen, L. H.

    2008-01-01

    Several exploration wells have intersected a Cenozoic coal-bearing, fluvial-deltaic mudstone and sandstone succession in the northeastern Vietnamese part of the Malay Basin, and have successfully tested seismically identified direct hydrocarbon indicators (DHIs). The oil and gas/condensate discovery ell 46-CN-1x encountered a _55m thick section of lacustrine mudstones having considerable potential as an oil source. Vitrinite reflectance (VR) measurements from these alginite-bearing rocks introdu...

  7. Contrasting isotopic mantle sources for proterozoic lamproites and kimberlites from the Cuddapah basin and eastern Dharwar craton: implication for proterozoic mantle heterogeneity beneath southern India

    International Nuclear Information System (INIS)

    Kimberlites intruding the Precambrian basement towards the western margin of the Cuddapah basin near Anantapur (1090 Ma) and Mahbubnagar (1360 Ma) in Andhra Pradesh have initial 87Sr/86Sr between 0.70205 to 0.70734 and ?Nd between +0.5 to +4.68. Mesoproterozoic lamproites (1380 Ma) from the Cuddapah basin (Chelima and Zangamarajupalle) and its NE margin (Ramannapeta) have initial 87Sr/86Sr between 0.70520 and 0.7390 and ?Nd from -6.43 to -8.29. Combined Sr- and Nd- isotopic ratios suggest that lamproites were derived from enriched sources which have time-averaged higher Rb/Sr and lower Sm/Nd ratios than the Bulk Earth whereas kimberlites were derived from depleted source with lower Rb/Sr and higher Sm/Nd ratios. Calculated TDM model ages suggest that the lamproite source enrichment (?2 Ga) preceded that of kimberlites (?1.37 Ga). Our work demonstrates the existence of isotopically contrasting upper mantle sources for southern Indian kimberlites and lamproites and provides evidence for a lateral, isotopically heterogeneous mantle beneath the Cuddapah basin and eastern Dharwar craton. The significance of our results in the context of diamond exploration is also highlighted. (author)

  8. STEM/AEM evidence for preservation of burial diagenetic fabrics in Devonian shales: Implications for fluid/rock interaction in cratonic basins (U.S.A.)

    Energy Technology Data Exchange (ETDEWEB)

    Hover, V.C.; Peacor, D.R.; Walter, L.M. [Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Geological Sciences

    1996-05-01

    Fabrics, microstructures, and compositions of authigenic illite-rich clays in Devonian intracratonic basin shales were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), and scanning transmission electron/analytical electron microscopy (STEM/AEM) methods in order to relate the extent of clay diagenesis to the timing of mudstone-system closure and to reconcile conflicting radiogenic and paleomagnetic ages obtained from these shales and associated limestones and bentonites. Authigenic illite in these Devonian shales is similar to post-transition illite-rich mixed-layer illite/smectite (I/S) in Gulf Coast and other young basin mudstones that have formed through replacement of detrital smectite or smectite-rich I/S without subsequent diagenetic modification. Preservation of burial diagenetic, authigenic, mixed-layer I/S microstructures in these Devonian shales implies that they have remained effectively closed systems following the smectite-to-illite transformation. Later Alleghenian (ca. 300 Ma) tectonic or fluid-flow events recorded by authigenic minerals in bentonites and carbonate lithologies throughout the US. Midcontinent are apparently not recorded in these Devonian shales. Preservation of diagenetic fabrics indicates that radiogenic isotope dating of cratonic basin shales should yield syndepositional to early burial diagenetic ages corresponding to the timing of I/S authigenesis.

  9. The earliest well-dated archeological site in the hyper-arid Tarim Basin and its implications for prehistoric human migration and climatic change

    Science.gov (United States)

    Han, WenXia; Yu, LuPeng; Lai, ZhongPing; Madsen, David; Yang, Shengli

    2014-07-01

    The routes and timing of human occupation of the Tibetan Plateau (TP) are crucial for understanding the evolution of Tibetan populations and associated paleoclimatic conditions. Many archeological sites have been found in/around the Tarim Basin, on the northern margin of the Tibetan Plateau. Unfortunately, most of these sites are surface sites and cannot be directly dated. Their ages can only be estimated based on imprecise artifact comparisons. We recently found and dated an archeological site on a terrace along the Keriya River. Our ages indicate that the site was occupied at ~ 7.0-7.6 ka, making it the earliest well-dated archeological site yet identified in the Tarim Basin. This suggests that early human foragers migrated into this region prior to ~ 7.0-7.6 ka during the early to mid-Holocene climatic optimum, which may have provided the impetus for populating the region. We hypothesize that the Keriya River, together with the other rivers originating from the TP, may have served as access routes onto the TP for early human foragers. These rivers may also have served as stepping stones for migration further west into the now hyper-arid regions of the Tarim Basin, leading ultimately to the development of the Silk Road.

  10. Stable isotopes in fossil mammals, fish and shells from Kunlun Pass Basin, Tibetan Plateau: Paleo-climatic and paleo-elevation implications

    Science.gov (United States)

    Wang, Yang; Wang, Xiaoming; Xu, Yingfeng; Zhang, Chunfu; Li, Qiang; Tseng, Zhijie Jack; Takeuchi, Gary; Deng, Tao

    2008-06-01

    We report the results of a stable isotope study of a late Pliocene fauna recently discovered in the Kunlun Mountain Pass area (˜ 4700 m above sea level) on the northern Tibetan Plateau. The ?13C values of enamel samples from modern herbivores from the Kunlun Pass Basin range from - 14.8 to - 10.6‰, with a mean of - 12.0 ± 0.7‰, indicating pure C3 diets consistent with the current dominance of C3 vegetation in the area. In contrast, enamel samples from fossil herbivores yielded ?13C values of - 5.4‰ to - 10.2‰ (with a mean of - 7.9 ± 1.3‰), significantly higher than those of modern herbivores in the area. The higher ?13C values indicate that these ancient herbivores, unlike their modern counterparts, had a variety of diets ranging from pure C3 to mixed C3/C4 vegetation. The local ecosystems in the Kunlun Pass area in the late Pliocene likely included grasslands that had small amounts of C4 grasses. The ?18O values of enamel from large herbivores shifted to higher values after the late Pliocene, indicating a significant change in the ?18O of local meteoric water. We estimate that there has been approximately 3.2‰ increase in annual ?18O values of meteoric water since ˜ 2-3 Ma, most likely driven by changes in the regional hydrological cycle possibly as a result of tectonic and climate change. The ?18O values of fossil fish teeth/bones and gastropod shells, along with abundance of aquatic plants and other invertebrate fossils, clearly indicate that the Kunlun Pass Basin once had plenty of water and was occupied by a freshwater lake in the late Pliocene. Our isotope data from both terrestrial and aquatic fossils suggest that the Kunlun Pass Basin was a hospitable place with a much warmer and wetter climate in the late Pliocene, very different from today's rock desert and cold steppe environments. The mean annual temperature in the late Pliocene estimated from the ?18O of fossil bone carbonate and paleo-water was about 10 ± 8 °C, much higher than the present-day mean annual temperature in the basin. If valid, the estimated temperature change would imply that the elevation of the basin has increased by ˜ 2700 ±1600 m since ˜ 2-3 Ma.

  11. The relationship between coal quality and coal resource parameters of Powder River and Williston Basin coal, Wyoming, Montana, and North Dakota

    Energy Technology Data Exchange (ETDEWEB)

    Ellis, M.S.; Stricker, G.D.; Gunther, G.; Ochs, A.M.; Flores, R.M.

    1998-12-31

    Clean, compliant coal from mines in the Northern Rocky Mountain and Great Plains region is utilized as fuel for coal-fired power plants in 26 states. More than 30 percent of the nation`s 1997 production was from Montana, North Dakota, and Wyoming. Production of clean, compliant coal from the region is estimated to increase to 415 million short tons by the year 2015. Studies in this region indicate a relationship between percent sulfur and ash and pounds of SO{sub 2} per million Btu and the resource parameters of coal thickness and overburden. The trends that the authors have observed indicate that both coal quality and the thickness of the coal and associated rocks are controlled by paleoenvironment and depositional setting.

  12. Noble gases in crude oils from the Paris Basin, France: Implications for the origin of fluids and constraints on oil-water-gas interactions

    Science.gov (United States)

    Pinti, Daniele L.; Marty, Bernard

    1995-08-01

    In order to investigate the potential of noble gases to trace the dynamics of oil reservoirs, we have analysed the abundance and isotopic composition of all noble gases (He, Ne, Ar, Kr, and Xe) in crude oils from the Paris Basin, France, using a new extraction and purification procedure. The main oil reservoirs are presently located in the Jurassic (Dogger) limestone and in the Triassic (Keuper) sandstone, but hydrocarbons originated from a common source rock formation located in the interbedded Liassic sequence. Despite this common origin, the abundance and isotopic ratios of the noble gases differ between the Dogger and the Keuper. The isotopic compositions of Kr and Xe are indistinguishable from that of air. 3He/ 4He ratios, higher than those predicted from radiogenic production in the sediments or in the crust, are attributed to the occurrence of mantle-derived 3He in the basin. Each sedimentary sequence is characterised by well defined and homogeneous 21Ne/ 22Ne and 40Ar/ 36Ar ratios, which average 0.0306 ± 0.0008 and 312 ± 10 for the Dogger and 0.0367 ± 0.0012 and 664 ± 30 for the Keuper, respectively. The main source of radiogenic noble gases appears to be the continental crust underlying the basin, with possible regional contributions of noble gas isotopes produced in the sediments. The helium and argon isotopic ratios of the Dogger oils are very similar to those observed in geothermal waters flowing in the Dogger aquifer throughout the basin, demonstrating that noble gases in oils derive from associated groundwaters. Oil reservoirs in the Paris Basin therefore accumulate noble gases from wide regions of the continental crust through cross-formational flow of groundwaters and subsequent partitioning into oil. This observation implies that noble gases cannot be directly used to date oils, but can provide time constraints if (1) water/oil interactions are quantified and (2) the residence time as well as the noble gas characteristics of associated groundwaters are known. Oil-water-gas partitioning processes are well recorded in the fractionation of noble gas elemental abundance. Two distinct processes have been identified: (1) accumulation of atmosphere-derived (ANG) and radiogenic noble gases both initially dissolved in groundwaters, resulting in a positive correlation between absolute amount of ANG and the extent of heavy noble gas fractionation and (2) subsequent fractional degassing, resulting in a negative correlation between ANG abundance and heavy noble gas fractionation. Degassing is particularly evident for the Keuper oils and might have occurred in the reservoirs following hydrodynamic gas stripping. The ANG abundance in the Dogger reservoirs requires that about one order of magnitude more water than presently observed has interacted with the oil. Given current estimates of the residence time for groundwaters in the Dogger aquifer, the duration of oil-water interaction is in qualitative agreement with a Palaeocene-Oligocene age for the major episode of secondary oil migration in the Paris Basin. High xenon contents in Keuper reservoirs suggest that they have experienced hydrodynamic interactions between flowing waters and oils for long time, and that the Trias might have reached hydrostatic condition only recently.

  13. Origin of banded structure and coal lithotype cycles in Kargali coal seam of East Bokaro sub-basin, Jharkhand, India: Environmental implications

    Indian Academy of Sciences (India)

    Ram Chandra Tewari; Zahid A Khan

    2015-04-01

    The Kargali seam of Early Permian Barakar cyclothems of East Bokaro sub-basin of Jharkhand, India is 12–30 m thick, splits into two parts, and extends throughout the length of the basin. It is made up of interbedded sequences and variable proportions of Vitrain, Clarain, Durain and Fusain. Application of embedded Markov chain model rejects the phenomenon of randomness in the repetition of coal lithotypes. The preferential upward transition path for coal lithotypes that can be derived for the Kargali top coal seam is: Vitrain $\\to$ Clarain $\\to$ Durain $\\leftrightarrow$ Fusain $\\to$ Vitrain, and for the Kargali bottom coal seam is: Clarain $\\leftrightarrow$ Vitrain $\\to$ Fusain $\\to$ Durain $\\to$ Clarain. By and large, the cyclic repetition of coal lithotypes is similar in the Kargali bottom and top seams. Among the noteworthy features are two-way transitions between Durain and Fusian in Kargali top and between Clarain and Vitrain in the case of Kargali bottom coal seam. Entropy analysis corroborates Markov chain and indicates the presence of type A-4 asymmetrical cycles of coal lithotypes. It is suggested that the banded structure of a coal seam is not a random feature and follows a definite cyclic pattern in the occurrence of coal lithotypes in vertical order and is similar to that described in Australian and European coal seams. Asymmetrical cyclic sequences are a normal, rather than an unusual condition, within coal seams. It is visualized that a gradual decline of toxic environment and ground water level resulted in the coal lithotype cycles in the Kargali seam of East Bokaro sub-basin. The close interbedding of Vitrain and Clarain is suggestive of seasonal fluctuation in anaerobic and aerobic conditions during peat formation.

  14. Trace-element systematics of sediments in the Murray-Darling Basin, Australia: Sediment provenance and palaeoclimate implications of fine scale chemical heterogeneity

    Energy Technology Data Exchange (ETDEWEB)

    Marx, Samuel K., E-mail: s.marx@uq.edu.au [Climate Research Group, School of Geography, Planning and Environmental Management, University of Queensland, St. Lucia, Brisbane, Qld 4072 (Australia); Kamber, Balz S. [Department of Earth Sciences, Laurentian University, Sudbury, Ontario, Canada P3E2C6 (Canada)

    2010-08-15

    A high-resolution dataset of trace element concentrations is presented for the Murray-Darling Basin, Australia, Australia's most important river system. The data were obtained by solution quadrupole ICP-MS resulting in concentrations for 44 elements. Of these, 21 were determined with a long-term external precision of better than 1% and a further 13 at a precision better than 2%. Trace element maps for the surface sediments constructed from such high precision data reveal small but coherent variations in the four major sub-catchments of the basin, even in ratios of elements with very similar geochemical behaviour, such as Y/Ho, Nb/Ta and Zr/Hf. The origin of these chemical fingerprints of drainage systems are discussed in terms of the geochemical character of the upper continental crust. The potential of trace element maps for palaeo-environmental and climatic reconstruction is then illustrated. First, a sample of dust collected in a trap located in the far southeastern corner of the study area is used to pinpoint the location of the dust source. Next the fine-scale change in down-stream alluvial sediment chemistry is analysed to estimate the importance of sediment contribution from tributaries with a view to reconstructing river flow dynamics. Finally, the chemistry of dune sediments is compared with surrounding floodplain alluvium to estimate relative age of deposition. These examples demonstrate that in low-elevation river systems, such as the Murray-Darling Basin, extended trace element maps of sediment offer substantially more applications than radiogenic isotope data alone.

  15. Basin geometry and cumulative offsets in the Eastern Transverse Ranges, southern California: Implications for transrotational deformation along the San Andreas fault system

    Science.gov (United States)

    Langenheim, V.E.; Powell, R.E.

    2009-01-01

    The Eastern Transverse Ranges, adjacent to and southeast of the big left bend of the San Andreas fault, southern California, form a crustal block that has rotated clockwise in response to dextral shear within the San Andreas system. Previous studies have indicated a discrepancy between the measured magnitudes of left slip on through-going east-striking fault zones of the Eastern Transverse Ranges and those predicted by simple geometric models using paleomagnetically determined clockwise rotations of basalts distributed along the faults. To assess the magnitude and source of this discrepancy, we apply new gravity and magnetic data in combination with geologic data to better constrain cumulative fault offsets and to define basin structure for the block between the Pinto Mountain and Chiriaco fault zones. Estimates of offset from using the length of pull-apart basins developed within left-stepping strands of the sinistral faults are consistent with those derived by matching offset magnetic anomalies and bedrock patterns, indicating a cumulative offset of at most ???40 km. The upper limit of displacements constrained by the geophysical and geologic data overlaps with the lower limit of those predicted at the 95% confidence level by models of conservative slip located on margins of rigid rotating blocks and the clockwise rotation of the paleomagnetic vectors. Any discrepancy is likely resolved by internal deformation within the blocks, such as intense deformation adjacent to the San Andreas fault (that can account for the absence of basins there as predicted by rigid-block models) and linkage via subsidiary faults between the main faults. ?? 2009 Geological Society of America.

  16. Trace-element systematics of sediments in the Murray-Darling Basin, Australia: Sediment provenance and palaeoclimate implications of fine scale chemical heterogeneity

    International Nuclear Information System (INIS)

    A high-resolution dataset of trace element concentrations is presented for the Murray-Darling Basin, Australia, Australia's most important river system. The data were obtained by solution quadrupole ICP-MS resulting in concentrations for 44 elements. Of these, 21 were determined with a long-term external precision of better than 1% and a further 13 at a precision better than 2%. Trace element maps for the surface sediments constructed from such high precision data reveal small but coherent variations in the four major sub-catchments of the basin, even in ratios of elements with very similar geochemical behaviour, such as Y/Ho, Nb/Ta and Zr/Hf. The origin of these chemical fingerprints of drainage systems are discussed in terms of the geochemical character of the upper continental crust. The potential of trace element maps for palaeo-environmental and climatic reconstruction is then illustrated. First, a sample of dust collected in a trap located in the far southeastern corner of the study area is used to pinpoint the location of the dust source. Next the fine-scale change in down-stream alluvial sediment chemistry is analysed to estimate the importance of sediment contribution from tributaries with a view to reconstructing river flow dynamics. Finally, the chemistry of dune sediments is compared with surrounding floodplain alluvium to estimate relative age of deposition. These examples demonstrate that in low-elevation river systems, such as the Murray-Darling Basin, extended trace element maps of sediment offer substantially more applications than radiogenic isotope data alone.

  17. A reassessment of the evidence for hydrothermal activity in the Neogene-Quaternary lacustrine environments of the Baza basin (Betic Cordillera, SE Spain) and its paleoecological implications

    Science.gov (United States)

    García-Aguilar, José Manuel; Guerra-Merchán, Antonio; Serrano, Francisco; Flores-Moya, Antonio; Delgado-Huertas, Antonio; Espigares, M. Patrocinio; Ros-Montoya, Sergio; Martínez-Navarro, Bienvenido; Palmqvist, Paul

    2015-03-01

    In a recent paper, García-Aguilar et al. (2014) reported on lithological, mineralogical and geochemical evidence of intense, tectonically-induced hydrothermal activity during the continental sedimentary infilling of the Baza basin, a postorogenic, intramontane area developed on the boundary between the Internal and External Zones of the Betic Cordillera, Southeast Spain (Fig. 1). This evidence includes the finding of sulfur contents, magnesium clays, fluorspar and celestine deposits, thermogene stromatolites and travertine growths in the latest Miocene (Turolian) to Middle Pleistocene lacustrine sediments and is particularly concentrated at certain stages and places (e.g. at Calabrian times in the Orce area).

  18. Late Cenozoic deformation of the Da'an-Dedu Fault Zone and its implications for the earthquake activities in the Songliao basin, NE China

    Science.gov (United States)

    Zhongyuan, Yu; Peizhen, Zhang; Wei, Min; Qinghai, Wei; Limei, Wang; Bin, Zhao; Shuang, Liu; Jian, Kang

    2015-08-01

    The Da'an-Dedu Fault Zone is a major tectonic feature cutting through the Songliao Basin from south to north in NE China. Five earthquakes with magnitudes over 5 that occurred during the past 30 years suggest the fault zone is a seismogenic structure with future seismic potential. The structural pattern, tectonic history, Quaternary activity and seismic potential have previously been unknown due to the Quaternary sedimentary coverage and lack of large historic earthquakes (M > 7). In this paper, we use seismic reflection profiles and drilling from petroleum explorations and shallow-depth seismic reflections to study those problems. The total length of the Da'an-Dedu Fault Zone is more than 400 km; modern seismicity delineates it into 4 segments each with a length of 90-100 km. In cross-section view, the folds and associated faults form a complex structural belt with a width of more than 10 km. Shallow-level seismic reflection across the Da'an-Dedu Fault Zone reveals that the Late Quaternary sediments were folded and faulted, indicating its present tectonic activity. The Da'an-Dedu Fault Zone and Songliao Basin have been subjected to three stages of tectonic evolution: a rifting stage characterized by normal faulting and extension (?145-112 Ma), a prolonged stage of thermal subsidence (?112-65 Ma), and a tectonic reversal that has been taking place since ?65 Ma. Our shallow-level reflection profiles show that the folding and reverse faulting have influenced the Late Quaternary sediments. The seismicity and moderate earthquakes suggest that the tectonic activity persists today. The deformation rate across the Da'an-Dedu Fault Zone, however, is measured to be very slow. In conjunction with the inference that most deformation in NE China may be taken up by the Yilan-Yitong Fault Zone bounding the Songliao Basin to the east, we suggest moderate earthquake potential and thus moderate seismic hazards along the Da'an-Dedu Fault Zone. The geological structures, which include anticlines and reverse faults, imply that the Da'an-Dedu Fault Zone has been a contractive structure since ?65 Ma, and this type of contraction dominates the tectonic deformation in the Songliao Basin and the entire NE China, although the reasons for these conditions need to be further studied.

  19. Health risks from large-scale water pollution: Current trends and implications for improving drinking water quality in the lower Amu Darya drainage basin, Uzbekistan

    Science.gov (United States)

    Törnqvist, Rebecka; Jarsjö, Jerker

    2010-05-01

    Safe drinking water is a primary prerequisite to human health, well being and development. Yet, there are roughly one billion people around the world that lack access to safe drinking water supply. Health risk assessments are effective for evaluating the suitability of using various water sources as drinking water supply. Additionally, knowledge of pollutant transport processes on relatively large scales is needed to identify effective management strategies for improving water resources of poor quality. The lower Amu Darya drainage basin close to the Aral Sea in Uzbekistan suffers from physical water scarcity and poor water quality. This is mainly due to the intensive agriculture production in the region, which requires extensive freshwater withdrawals and use of fertilizers and pesticides. In addition, recurrent droughts in the region affect the surface water availability. On average 20% of the population in rural areas in Uzbekistan lack access to improved drinking water sources, and the situation is even more severe in the lower Amu Darya basin. In this study, we consider health risks related to water-borne contaminants by dividing measured substance concentrations with health-risk based guideline values from the World Health Organisation (WHO). In particular, we analyse novel results of water quality measurements performed in 2007 and 2008 in the Mejdurechye Reservoir (located in the downstream part of the Amu Darya river basin). We furthermore identify large-scale trends by comparing the Mejdurechye results to reported water quality results from a considerable stretch of the Amu Darya river basin, including drainage water, river water and groundwater. The results show that concentrations of cadmium and nitrite exceed the WHO health-risk based guideline values in Mejdurechye Reservoir. Furthermore, concentrations of the since long ago banned and highly toxic pesticides dichlorodiphenyltrichloroethane (DDT) and ?-hexachlorocyclohexane (?-HCH) were detected in the reservoir water for the first time in a decade. However, a relatively pronounced temporal variability in concentrations was observed for many of the substances, implying that the reservoir could contain low-risk waters temporarily. Health risk factors related to lead and chromium concentrations in groundwater were up to 200 times higher than for river water. The identified major divergence in health risk between groundwater and surface water illuminates the risk of using groundwater for drinking water supply during recurrent surface water deficits in the study area. However, the severe water scarcity and lack of financial resources in the region makes the choices of alternative water supply sources limited. Due to the presence of multiple contaminants, it appears reasonable that the aggregated toxicity of contaminant mixtures should be in focus in surface and groundwater water monitoring and management in the region. Key words: Aral Sea, Drinking water, Groundwater, Health Risk, Surface Water

  20. Magnetic mineral study of Holocene marine sediments from the Alfonso Basin, Gulf of California - implications for depositional environment and sediment sources

    Directory of Open Access Journals (Sweden)

    L. Pérez Cruz

    2009-07-01

    Full Text Available Results of a rock magnetic study of marine sediments from the Alfonso Basin, Bay of La Paz are used to investigate sediment sources and depositional environment in the southern Gulf of California during the Holocene. Radiocarbon dating provides stratigraphic control, with age for the core bottom sediments of 7597-7831 cal. yr B.P. Magnetic signal is dominated by fine-grained titanomagnetites, derived from the silicic volcanic units surrounding the Bay of La Paz. Magnetic mineralogy is relatively homogenous as seen in bulk magnetic properties of low-field susceptibility, remanent intensity and coercivity. Magnetic hysteresis loops show strong variable paramagnetic components; after paramagnetic correction loops show saturation at low fields and high saturation magnetization values. Plots of hysteresis parameter ratios for domain state show that samples group in the pseudo-single domain field, with mixtures of single and multi-domain particles. Magnetic susceptibility log shows relatively high frequency dependence factors, particularly for the Middle Holocene, suggesting contribution of fine-grained superparamagnetic minerals related to eolian deposition. The well-preserved laminated sequence indicates predominant anoxic conditions in the basin floor. Depositional environment had a dominant supply of pluvial detrital sediments and eolian fimaterial with less abundant biogenic input.

  1. Population Structure in the Roundtail Chub (Gila robusta Complex) of the Gila River Basin as Determined by Microsatellites: Evolutionary and Conservation Implications.

    Science.gov (United States)

    Dowling, Thomas E; Anderson, Corey D; Marsh, Paul C; Rosenberg, Michael S

    2015-01-01

    Ten microsatellite loci were characterized for 34 locations from roundtail chub (Gila robusta complex) to better resolve patterns of genetic variation among local populations in the lower Colorado River basin. This group has had a complex taxonomic history and previous molecular analyses failed to identify species diagnostic molecular markers. Our results supported previous molecular studies based on allozymes and DNA sequences, which found that most genetic variance was explained by differences among local populations. Samples from most localities were so divergent species-level diagnostic markers were not found. Some geographic samples were discordant with current taxonomy due to admixture or misidentification; therefore, additional morphological studies are necessary. Differences in spatial genetic structure were consistent with differences in connectivity of stream habitats, with the typically mainstem species, G. robusta, exhibiting greater genetic connectedness within the Gila River drainage. No species exhibited strong isolation by distance over the entire stream network, but the two species typically found in headwaters, G. nigra and G. intermedia, exhibited greater than expected genetic similarity between geographically proximate populations, and usually clustered with individuals from the same geographic location and/or sub-basin. These results highlight the significance of microevolutionary processes and importance of maintaining local populations to maximize evolutionary potential for this complex. Augmentation stocking as a conservation management strategy should only occur under extreme circumstances, and potential source populations should be geographically proximate stocks of the same species, especially for the headwater forms. PMID:26473600

  2. Crustal structure of the eastern Algerian continental margin and adjacent deep basin: implications for late Cenozoic geodynamic evolution of the western Mediterranean

    Science.gov (United States)

    Bouyahiaoui, B.; Sage, F.; Abtout, A.; Klingelhoefer, F.; Yelles-Chaouche, K.; Schnürle, P.; Marok, A.; Déverchère, J.; Arab, M.; Galve, A.; Collot, J. Y.

    2015-06-01

    We determine the deep structure of the eastern Algerian basin and its southern margin in the Annaba region (easternmost Algeria), to better constrain the plate kinematic reconstruction in this region. This study is based on new geophysical data collected during the SPIRAL cruise in 2009, which included a wide-angle, 240-km-long, onshore-offshore seismic profile, multichannel seismic reflection lines and gravity and magnetic data, complemented by the available geophysical data for the study area. The analysis and modelling of the wide-angle seismic data including refracted and reflected arrival travel times, and integrated with the multichannel seismic reflection lines, reveal the detailed structure of an ocean-to-continent transition. In the deep basin, there is an ˜5.5-km-thick oceanic crust that is composed of two layers. The upper layer of the crust is defined by a high velocity gradient and P-wave velocities between 4.8 and 6.0 km s-1, from the top to the bottom. The lower crust is defined by a lower velocity gradient and P-wave velocity between 6.0 and 7.1 km s-1. The Poisson ratio in the lower crust deduced from S-wave modelling is 0.28, which indicates that the lower crust is composed mainly of gabbros. Below the continental edge, a typical continental crust with P-wave velocities between 5.2 and 7.0 km s-1, from the top to the bottom, shows a gradual seaward thinning of ˜15 km over an ˜35-km distance. This thinning is regularly distributed between the upper and lower crusts, and it characterizes a rifted margin, which has resulted from backarc extension at the rear of the Kabylian block, here represented by the Edough Massif at the shoreline. Above the continental basement, an ˜2-km-thick, pre-Messinian sediment layer with a complex internal structure is interpreted as allochthonous nappes of flysch backthrusted on the margin during the collision of Kabylia with the African margin. The crustal structure, moreover, provides evidence for Miocene emplacement of magmatic intrusions in both the deep basin and the continental margin. Based on the crustal structure, we propose that the eastern Algerian basin opened during the southeastward migration of the European forearc before the collision, along a NW-SE elongated spreading centre that ran perpendicular to the subduction trend. Such an atypical geometry is explained by the diverging directions of the subduction rollback during the backarc opening: eastward for the Corsica-Sardinia block, and southward for the Kabylian blocks. This geometry of the forearc can be interpreted as the surface expression of a slab tear at depth, which is responsible for atypical magmatism in the overlying backarc oceanic basin.

  3. The strong diachronous Muschelkalk/Keuper facies shift in the Central European Basin: implications from the type-section of the Erfurt Formation (Lower Keuper, Triassic) and basin-wide correlations

    Science.gov (United States)

    Franz, Matthias; Henniger, Matthias; Barnasch, Jens

    2013-04-01

    The transition from the shallow marine Upper Muschelkalk Sea to the Lower Keuper fluvial plain represents the most diachronous facies shift of the entire Germanic Triassic. The type-section of the fluvial Lower Keuper (Erfurt Formation) is described in detail for the first time including biostratigraphic dating of the Muschelkalk/Keuper boundary. The type-section is integrated into a NNE-SSW cross section through the Central European Basin, and the Muschelkalk/Keuper facies shift is constrained by high-resolution conodont and ceratite biostratigraphy. Thus, the fundamental changes in palaeogeography, shifts of facies belts and stratal pattern architecture are visualised. Forced by a rapid transgression from Tethyan waters, the shallow marine Upper Muschelkalk Sea attained its maximum flooding in the lower conodont zone 2 ( sequens/pulcher to philippi/robustus zones). Subsequent slow continuous regression to the South was accompanied by step-by-step progradation of coastal to fluvial plain environments of the Lower Keuper, culminating in a fluvial plain extending to South Germany. Based on stratal patterns, an improved sequence-stratigraphic interpretation for the Upper Muschelkalk/Lower Keuper interval is suggested. In combination with biostratigraphic arguments, the new sequence-stratigraphy points to a revised correlation of this interval within the Tethyan Triassic, incorporating the positions of the Anisian/Ladinian and Fassanian/Longobardian boundaries.

  4. Magnetochronology of the Feiliang Paleolithic site in the Nihewan Basin and implications for early human adaptability to high northern latitudes in East Asia

    Science.gov (United States)

    Deng, Chenglong; Xie, Fei; Liu, Caicai; Ao, Hong; Pan, Yongxin; Zhu, Rixiang

    2007-07-01

    We present a new magnetostratigraphic dating of the Feiliang Paleolithic site in the Nihewan Basin, northern China. Partially-oxidized magnetite and hematite were identified as the main carriers for the characteristic remanent magnetizations of the fluvio-lacustrine sediments. Paleomagnetic results suggest that the sequence recorded the very early Brunhes chron and the upper Matuyama chron, including the Jaramillo subchron. The Feiliang artifact layer was determined to be within the pre-Jaramillo Matuyama chron, with an estimated age of ca. 1.2 Ma. Our finding, coupled with previously published magnetochronology, strongly indicates a prominent early human flourishing in the high northern latitudes of East Asia during or just prior to the Mid-Pleistocene climate transition.

  5. Paleomagnetic Evidence From Volcanic Units of Valsequillo Basin for the Laschamp Geomagnetic Excursion, and Implications for Early Human Occupation in Central Mexico

    Science.gov (United States)

    Rocha, J.; Gogichaishvili, A.; Martin Del Pozzo, A.; Urrutia-Fucugauchi, J.; Soler, A. M.

    2007-12-01

    Alleged human and animal footprints were found within the upper bedding surfaces of the Xalnene volcanic ash layer that outcrops in Valsequillo basin, south of Puebla, Mexico (Gonzalez et al., Quaternary Science Reviews doi: 10.1016/j.quascirev, 2005). The ash has been dated to 40 ka by means of optically stimulated luminescence analysis. This was held as new evidence that America was colonized earlier. We carried out paleomagnetic and rock magnetic analysis of 18 Xalnene ash block and core samples collected at two distinct localities, and nineteen standard paleomagnetic cores belonging to nearby monogenetic volcanoes. Our data yield evidence that both volcanic lava flow and Xalnene ash were emplaced at during the Laschamp geomagnetic event spanning from about 45 to 39 ka. This interpretation indicates that Valsequillo probably remains one of the sites of early human occupation in the Americas, producing evidence of early arrival.

  6. The upper limit of maturity of natural gas generation and its implication for the Yacheng formation in the Qiongdongnan Basin, China

    Science.gov (United States)

    Su, Long; Zheng, Jianjing; Chen, Guojun; Zhang, Gongcheng; Guo, Jianming; Xu, Yongchang

    2012-08-01

    Vitrinite reflectance (VR, Ro%) measurements from residual kerogen of pyrolysis experiments were performed on immature Maoming Oil Shale substituted the samples for the gas-prone source rocks of Yacheng formation of the Qiongdongnan Basin in the South China Sea. The work was focused on determination an upper limit of maturity for gas generation (ULMGG) or "the deadline of natural gas generation". Ro values at given temperatures increase with increasing temperature and prolonged heating time, but ?Ro-value, given a definition of the difference of all values for VR related to higher temperature and adjacent lower temperature in open-system non-isothermal experiment at the heating rate of 20 °C/min, is better than VR. And representative examples are presented in this paper. It indicates that the range of natural gas generation for Ro in the main gas generation period is from 0.96% to 2.74%, in which ?Ro is in concordance with the stage for the onset and end of the main gas generation period corresponding to 0.02% up to 0.30% and from 0.30% up to 0.80%, respectively. After the main gas generation period of 0.96-2.74%, the evolution of VR approach to the ULMGG of the whole rock for type II kerogen. It is equal to 4.38% of VR, where the gas generation rates change little with the increase of maturation, ?Ro is the maximum of 0.83% corresponding to VR of 4.38%Ro, and the source rock does not nearly occur in the end process of hydrocarbon gas generation while Ro is over 4.38%. It shows that it is the same the ULMGG from the whole rock for type II kerogen as the method with both comparison and kinetics. By comparing to both the conclusions of pyrolysis experiments and the data of VR from the source rock of Yacheng formation on a series of selected eight wells in the shallow-water continental shelf area, it indicate that the most hydrocarbon source rock is still far from reaching ULMGG from the whole rock for type II kerogen. The source rock of Yacheng formation in the local areas of the deepwater continental slope basin have still preferable natural gas generative potential, especially in the local along the central depression belt (namely the Ledong, Lingshui, Songnan and Baodao sags from southwest to northeast) from the depocenter to both the margin and its adjacent areas. It help to evaluate the resource potential for oil and gas of the hydrocarbon source rock in the deepwater continental slope of the Qiongdongnan Basin or other basins with lower exploration in the northern of the South China Sea and to reduce the risk in exploration.

  7. Cooling history of the Upper Cretaceous Palgongsan Granite, Gyeongsang Basin, SE Korea and its tectonic implication for uplift on the active continental margin

    Science.gov (United States)

    Lim, Hyoun Soo; Lee, Yong Il

    2005-07-01

    Apatite and zircon fission track analyses were carried out to reconstruct the cooling and inferred uplift history of the Cretaceous Palgongsan Granite, Gyeongsang Basin, Korea. The Palgongsan Granite is one of the Bulguksa intrusive rocks that formed by arc-related plutonism during Late Cretaceous to Early Tertiary time. Fission track dating of the Palgongsan Granite yielded nearly concordant ages of 53 and 65 Ma for apatite and zircon, respectively. The Palgongsan Granite also shows a simple cooling pattern, which suggests that it has not been affected by any thermal event after emplacement. The cooling history derived from fission track data combined with other thermochronometric data indicates that the Palgongsan Granite experienced relatively rapid cooling in earlier stage (> 30 °C/Ma). The initial rapid cooling rate during the Late Cretaceous has been caused by the large thermal contrast between the granite body and the country rocks. After reaching thermal equilibrium with the surrounding country rocks, the cooling rate of the Palgongsan Granite was abruptly decreased in late stage. In this late stage, the decelerated cooling rate is interpreted to have been controlled by uplift and erosion processes, and the average exhumation rate is calculated to be ca. 50 m/my over the temperature range from 100 °C to the surface temperature. The cooling history of the Palgongsan Granite is in good agreement with that of the Ryoke Granitic Belt in Southwest Japan, as well as those of the Taebaeksan Range and other Bulguksa intrusive rocks in the Gyeongsang Basin. This suggests that such cooling was probably caused by regional uplift and exhumation processes on the East Asian active continental margin. Compared with the uplift rates of the Andes, the uplift rates on the eastern Pacific margin appear to be higher than those on the western Pacific margin.

  8. Aeolian origin of Rb/Sr ratio in lacustrine sediments of enclosed Qaidam Basin in Tibetan Plateau and implications for palaeoenvironmental reconstruction

    Science.gov (United States)

    Lai, Zhongping; An, Fuyuan

    2015-04-01

    Elements Strontium (Sr) and Rubidium (Rb) are easily fractionated during the processes of weathering, because Rb appears to be immobile while Sr appears mobile. The Rb/Sr ratio is an important environmental proxy in both loess and lacustrine sediments for reconstructing palaeomonsoon climate. In loess it serves as an indicator of chemical weathering and an index of the East Asian summer monsoon intensity. In lake sediments, if lithologies in the source area and detrital input have no significant influence on the Rb/Sr ratio, this ratio can also serve as a sensitive proxy of paleoclimate changes. The Rb/Sr ratio in loess-paleosol sequence would increase significantly with the enhancement of weathering intensity, while in lacustrine sediments the ratio shows the opposite pattern. However, in this study we found that, in a lacustrine core from the Qarhan Salt Lake of the enclosed Qaidam Basin in the Tibetan Plateau, the pattern of fluctuations in Rb/Sr ratio is similar to that of loess-paleosol sequence rather than to that of typical lacustrine sediments. In order to exam the environment significance of Rb/Sr ratio for this lake core, a number of proxies are measured (halite content, calcite content, Fe element content, grain size fractions, and values of grain-size discriminant function). Our data suggest the aeolian origin of Rb/Sr ratio. We thus attribute this unexpected pattern of fluctuations in Rb/Sr ratio to the input of abundant dust flux due to strong aeolian activity in this region. We then propose that use of Rb/Sr ratio as a climatic proxy in lacustrine sediments should be cautious in arid areas where aeolian input is abundant, and that the Rb/Sr ratio in lacustrine sediments of the Qaidam Basin could indicate geochemical information of provenance.

  9. Karyotype structure of Hypostomus cf. plecostomus (Linnaeus, 1758) from Tapajós River basin, Southern Amazon: occurrence of sex chromosomes (ZZ/ZW) and their evolutionary implications.

    Science.gov (United States)

    Oliveira, L C; Ribeiro, M O; Dutra, E S; Zawadzki, C H; Portela-Castro, A L B; Martins-Santos, I C

    2015-01-01

    Hypostomus is a group of fish with numerical and struc-tural karyotypic variability. Among them, only six species, three of which belong to the Amazon basin, show a sex chromosome. In this study, we present the karyotype structure of Hypostomus cf. plecos-tomus from the Teles Pires river basin in the municipality of Alta Flo-resta, MT. The species has 2n = 68 and the karyotype formula 14m+ 24sm+ 14st+ 16a [fundamental number (FN) = 120] in males and 15m+ 24sm+14st+15a (FN = 121) in females and sex chromosomes ZZ/ZW. Argyrophilic nucleolar organizer regions (AgNORs) were identified in two pairs of chromosomes at different positions: short arm of the pair 21and long arm of the pair 27, matching the signals displayed by 18S FISH and indicating multiple NORs. Analysis of band C detected few blocks of constitutive heterochromatin in the pericentromeric regions of most chromosomes and the telomeric regions of some pairs, includ-ing the nucleolar pair 21. However, large blocks on the long arm of the nucleolar pair 27 still stood out. GC-rich heterochromatin (CMA3) was visualized only coincidently with nucleolar sites. Mapping of 5S rDNA sites with FISH revealed markings in eight chromosomes, demonstrat-ing synteny between the 18S and 5S sites. The data obtained for H. cf. plecostomus are important for taxonomic studies of this Amazon com-plex "H. plecostomus group". The occurrence of sex chromosomes in Amazon species of Hypostomus suggests an evolutionary event that is independent of other species in the group. PMID:26125870

  10. Nd, Sr-isotopic provenance and trace element geochemistry of Amazonian foreland basin fluvial sands, Bolivia and Peru: Implications for ensialic Andean orogeny

    International Nuclear Information System (INIS)

    Nd and Sr isotopes and the trace element contents, including the rare earths, were determined for fluvial sands of lithic arenite composition from the Madre de Dios foreland basin of Bolivia and Peru. On standard petrologic ternary diagrams, the sands fall in the recycled orogen provenance field and thus are similar to typical ancient foreland basin composition. The average rare earth elemental pattern of the sands is identical to the upper continental crustal average, as estimated from post-Archean composite shales of different continents. Ratio of Th/U, Co/Th, La/Sc and Th/Sc of the fluvial sands are intermediate between an average magmatic arc and an upper crustal average compositions. The dispersion of some trace elemental patterns in the sands can be attributed to fractionation of dense minerals, including zircon, during the sedimentation process. The variations of Nd isotopes in conjunction with the petrographic parameters of lithic metamorphic (Lm) and volcanic (Lv) fragments allow a two-fold classification of the sands. These two sand types can be interpreted in terms of mixing among three different provenances: one volcanic rock-suit with less negative ?Nd(O) parameter than the other volcanic suite, and a third metasedimentary source with ?Nd(O) value of around -12, which is considered to be similar to the average western Brazilian shield composition. Thus the overall compositions of the sands has been modeled as mechanical mixtures of two components, an Andean magmatic arc and the Brazilian shield-derived metasediments. The model is strongly supported by a plot of ?Nd(O) versus ?Sr(O) of the sands. In this plot, the Type 1 and 2 sands define two coherent hyperbolic trends contiguous with two different portions of the Andean magmatic trend. (orig./WB)

  11. Petrography and major element geochemistry of the Permo-Triassic sandstones, central India: Implications for provenance in an intracratonic pull-apart basin

    Science.gov (United States)

    Ghosh, Sampa; Sarkar, Soumen; Ghosh, Parthasarathi

    2012-01-01

    Detrital mode, composition of feldspars and heavy minerals, and major element chemistry of sandstones from the Permo-Triassic succession in the intracratonic Satpura Gondwana basin, central India have been used to investigate provenance. The Talchir Formation, the lowermost unit of the succession, comprises glacio-marine and glacio-fluvial deposits. The rest of the succession (base to top) comprising the Barakar, Motur, Bijori, Pachmarhi and Denwa formations, largely represent variety of fluvial depositional systems with minor fluvio-deltaic and fluvio-lacustrine sedimentation under a variety of climatic conditions including cold, warm, arid, sub-humid and semi-arid. QFL compositions of the sandstones indicate a predominantly continental block provenance and stable cratonic to fault-bounded basement uplift tectonic setting. Compositional maturity of sandstones gradually increases upwards from the Early Permian Talchir to the Middle Triassic Denwa but is punctuated by a sharp peak of increased maturity in the Barakar sandstones. This temporal change in maturity was primarily controlled by temporal variation in fault-induced basement uplift in the craton and was also influenced by climatic factors. Plots of different quartz types suggest plutonic source rocks for the Talchir sandstones and medium-to high-rank metamorphic plus plutonic source rocks for the younger sandstones. Composition of alkali feldspars in the Permo-Triassic sandstones and in different Precambrian rocks suggests sediment derivation from felsic igneous and metasedimentary rocks. Compositions of plagioclase in the Talchir and Bijori sandstones are comparable with those of granite, acid volcanic and metasedimentary rocks of the Precambrian basement suggesting the latter as possible source. Rare presence of high-K plagioclase in the Talchir sandstones, however, indicates minor contribution from volcanic source rock. Exclusively plagioclase-bearing metasedimentary rock, tonalite gneiss and mafic rocks are the probable sources of plagioclase in the Upper Denwa sandstones. Quartz-rich nature of the sandstones, predominance of K-feldspar over plagioclase and albite rich character of plagioclase in the sandstones is consistent with deposition in an intracratonic, pull-apart basin like the Satpura Gondwana basin. Composition of garnet and its comparison with that from the Precambrian basement rocks suggests mica-schist and amphibolite as possible sources. Predominance of dravite variety of tourmaline in the Permian sandstones suggests sediment supply from metasedimentary rocks. Presence of both dravite and schorl variety of tourmaline in subequal amount in the Triassic sandstones indicates sediment derivation from granitic and metasedimentary rocks. However, schorl-bearing rocks are absent in the basement complex of the study area. A-CN-K plot suggests granites, acid volcanic rock and meta-sediments of the basement as possible sources of the Talchir sandstones and metasedimentary rocks for the Barakar to Pachmarhi sandstones. The Denwa sandstones were possibly derived from K-feldspar-free, plagioclase-bearing metasediments, mafic rocks and tonalite gneiss. Chemical Index of Alteration (CIA) values suggest low intensity source rock weathering for the Talchir sandstones and higher intensity source rock weathering for the others. Various bivariate plots of major oxides composition of the sandstones suggest passive to active continental margin setting and even arc tectonic setting for a few samples.

  12. Tectonic repetitions of the Early Cretaceous Agrio Formation in the Chos Malal fold-and-thrust belt, Neuquén Basin, Argentina: Geometry, kinematics and structural implications for Andean building

    Science.gov (United States)

    Turienzo, M.; Sánchez, N.; Dimieri, L.; Lebinson, F.; Araujo, V.

    2014-08-01

    The Neuquén Basin, developed in a retroarc setting in the central-west of Argentina, contains more than 6000 m of Mesozoic marine and continental sedimentary rocks. These rocks were deformed during the Andean orogeny leading to several thick and thin-skinned fold-and-thrust belts. The Early Cretaceous Agrio Formation is composed by a thick marine succession predominantly of black shales in which highlights a thin fluvial-aeolian sandy interval named Avilé Member. The Avilé Member, one of the most important hydrocarbon reservoirs of the Neuquén Basin, constitutes an excellent structural marker. At the Chos Malal fold-and-thrust belt, the strong mechanical anisotropy given by the contrasting lithology of the Avilé Member within the Agrio Formation favored the location of detachments along the shales and ramps affecting the sandstones during the Andean compression. Detailed field mapping at the Chacay Melehue area allowed us to recognize tectonic repetitions of the Avilé Member, which form imbrications in the simplest case whereas in other places constitute a more complex combination of imbrications, including fault-bend folding that duplicates stratigraphic sequences and fault-propagation folding that deforms more intensely the duplicated units. Along three structural cross-sections we illustrate the geometry of these tectonic repetitions of the Agrio Formation, which in the northern area have an eastward-vergence and in the central and southern regions show a clear westward-vergence. A tear fault along the arroyo Chacay Melehue could explain this vergence change. Forward modeling of the structures at the central cross-section, where a backthrust system produced imbrication, duplication and folding of the Agrio Formation, allows us to propose a balanced kinematic reconstruction of this complex structure and to compare the features produced at different stages of the deformation sequence with field observations. Our kinematic interpretation shows that the tectonic repetitions of the Agrio Formation involve 3 km of shortening above a basal detachment within the lowermost black shales. Based on a regional balanced cross-section constructed from the basement-cored Cordillera del Viento anticlinorium toward the east, across the thin-skinned sector of the Chos Malal FTB, it is possible to connect the backthrust system with east-vergent fault-bend folds that involve the stratigraphic units below the Agrio Formation. Finally, we propose a regional structural model considering the Cordillera del Viento as a basement wedge related to a low angle Andean thrust that is inserted into the sedimentary cover producing structures of different order, which evidence a strong relationship between thick and thin-skinned structures during the Andean orogeny.

  13. Predominance of even carbon-numbered n-alkanes from lacustrine sediments in Linxia Basin, NE Tibetan Plateau: Implications for climate change

    International Nuclear Information System (INIS)

    Research highlights: ? This study reports the first observation of predominant even carbon-numbered n-alkanes of sediments in the continuous lacustrine-sedimentary section (Maogou) from the Late Miocene to the Early Pliocene (13-4.4 Ma) in the Linxia Basin, NE Tibetan Plateau. ? Certain types of special autochthonous bacteria are a possible source for the special distribution of even carbon-numbered n-alkanes in lacustrine sediments. ? These bacteria may have a high production rate in weak oxic-anoxic and arid depositional environments, in which a variety of geochemical parameters have recorded palaeoclimate change. ? A close correspondence among the low ratio of n-C27/n-C31, the heavy ?13C values of TOC and a strong even carbon-number predominance (low OEP16-20 values) from approximately 6.5 to 4.4 Ma and at approximately 8 Ma in the studied section suggests that n-alkanes with a high predominance of even carbon-numbers may be treated as geochemical proxies for arid climate. - Abstract: This study reports the first observation of predominant even C-numbered n-alkanes from sediments in the continuous lacustrine-sedimentary section (Maogou) from the Late Miocene to the Early Pliocene (13-4.4 Ma) in the Linxia Basin, NE Tibetan Plateau. The n-alkanes showed a bimodal distribution that is characterised by a centre at n-C16-n-C20 with maximum values at n-C18 and n-C27-n-C31 as well as at n-C29. The first mode shows a strong even C-number predominance (OEP16-20 0.34-0.66). In contrast, the second mode has a strong odd C-number predominance (OEP27-31 1.20-2.45). Certain types of special autochthonous bacteria are a possible source for this distribution of even C-numbered n-alkanes in lacustrine sediments. These bacteria may have a high production rate in weak oxic-anoxic and arid depositional environments, in which a variety of geochemical parameters have recorded palaeoclimate change.

  14. Synchrotron X-ray fluorescence (SXRF) analysis of palaeofluid chemistry from the McArthur River uranium deposit, Athabasca Basin, Canada: Results and implications

    International Nuclear Information System (INIS)

    Unconformity-type uranium deposits of the Athabasca Basin in northern Saskatchewan and northeastern Alberta, Canada, represent the world's highest-grade and large-tonnage uranium resources. However, despite the wealth of research on these deposits, almost no information is available regarding the trace element content of the ore forming fluids and especially about their metal contents. We present here, for the first time, information on the trace element geochemistry of the o reforming fluids that resulted in the formation of the world-class McArthur River uranium deposit using the SXRF technique. Measurements were performed at the Hamburger Synchrotronstrahlungslabor (HASYLAB), part of the Deutsches Elektronen-Synchrotron (DESY), using the micro-fluorescence beamline (beamline L). The fluid inclusions investigated by SXRF are ca. 20 to 50 microns in size, and are either two (L+V) or three (L+V+S) phase inclusions. Solid phases include halite, phyllosilicates and haematite, and, possibly, dravite. The results indicate that all the fluid inclusions contain Fe, Br and Sr. In addition, there are a number of other elements present: Ca, K, Ce, Cu, Pb, U, Zn and Zr. The presence of these metals varies between inclusions and samples. On the basis of element associations, the data suggest that two different fluids may be present 1) Br-Sr-Fe +- U-Pb-Ce and 2) Br-Sr-Fe-Ca +-Zr-Zn-Ce. Preliminary analysis suggest that U is present in both the NaCl- and CaCl2-dominant fluids. With the exception of Fe, transition metals are rarely detected in the analyses. However, Zn was detected in the majority of inclusions in samples AJM2 and MAC8, however U was not detected in these samples. In contrast, those samples that did contain uranium were devoid of Zn. This may indicate that Zn and U were transported in mutually exclusive fluids. The general absence of transition metals such as Ni, Cu and Co is not unexpected. McArthur River is poor in these metals, compared to other deposits/occurrences in the Athabasca Basin, such as Key Lake and Moore Lakes. Future work will examine fluid inclusions from these and other areas in order to 1) further characterize the ore fluid in terms of trace element chemistry, 2) determine if the uranium and base metals were transported in a single or multiple fluid(s), and 3) quantify the results

  15. New glacial evidences at the Talacasto paleofjord (Paganzo basin, W-Argentina) and its implications for the paleogeography of the Gondwana margin

    Science.gov (United States)

    Aquino, Carolina Danielski; Milana, Juan Pablo; Faccini, Ubiratan Ferrucio

    2014-12-01

    The Talacasto paleovalley is situated in the Central Precordillera of San Juan, Argentina, where upper Carboniferous-Permian rocks (Paganzo Group) rest on Devonian sandstones of the Punta Negra Formation. This outcrop is an excellent example of a glacial valley-fill sequence that records at least two high-frequency cycles of the advance and retreat of a glacier into the valley. The paleocurrent analysis shows transport predominantly to the south, indicating that at this site the ice flow differs from the other nearby paleovalleys. Evidence of the glacial origin of this valley can be seen in the glacial striae on the valley's sides, as well as the U-shape of the valley, indicated by very steep locally overhanging valley walls. Deglaciation is indicated by a set of retransported conglomerates deposited in a shallow-water environment followed by a transgressive succession, which suggests eustatic rise due to meltwater input to the paleofjord. The complete sedimentary succession records distinct stages in the evolution of the valley-fill, represented by seven stratigraphical units. These units are identified based on facies associations and their interpreted depositional setting. Units 1 to 5 show one cycle of deglaciation and unit 6 marks the beginning of a new cycle of glacier advance which is characterized by different types of glacial deposits. All units show evidence of glacial influence such as dropstones and striated clasts, which indicates that the glaciers were always present in the valley or in adjacent areas during sedimentation. The Talacasto paleofjord provides good evidence of the Late Paleozoic Gondwana glaciation in western Argentina and examples of sedimentary successions which have been interpreted as being deposited by a confined wet-based glacier in advance and retreat cycles, with eventual release of icebergs into the basin. The outcrop is also a key for reconstructing the local glacial paleogeography, and it suggests a new interpretation that is not in agreement with previous studies. Finally, the importance of the Talacasto paleovalley for the Paganzo basin lies in its orientation, because it allows the reconstruction of the ice paleoflow and indication, for the first time, that marine ingressions into this area were not taking place along the Jachal trough, as expected, but along a different connection to the sea, which for this work we will call the San Juan Paleotrough.

  16. Application of integrated vitrinite reflectance and FAMM analyses for thermal maturity assessment of the northeastern Malay Basin, offshore Vietnam: Implications for petroleum prospectivity evaluation

    DEFF Research Database (Denmark)

    Petersen, H. I.; Sherwood, N.

    2008-01-01

    Several exploration wells have intersected a Cenozoic coal-bearing, fluvial-deltaic mudstone and sandstone succession in the northeastern Vietnamese part of the Malay Basin, and have successfully tested seismically identified direct hydrocarbon indicators (DHIs). The oil and gas/condensate discovery ell 46-CN-1x encountered a _55m thick section of lacustrine mudstones having considerable potential as an oil source. Vitrinite reflectance (VR) measurements from these alginite-bearing rocks introduce several problems in thermal maturity evaluation, including associated VR suppression and delineation of cavings and bitumens. Reliable thermal maturity gradients, however, may be established using a combination of conventional VR measurements and ‘equivalent VR' (EqVR) values derived from the fluorescence alteration of multiple macerals (FAMM) technique. These measurements, performed on dispersed organic matter (DOM) in cuttings from 46-CN-1x, allow separation of low-reflecting bitumens and vitrinite in cavings from indigenous vitrinite and the FAMM results indicate VR suppression of 0.14% in an alginite-bearing mudstone with a high Hydrogen Index value. On the basis of available ‘raw' VR data, a highly irregular maturity trend is determined, with the deepest sample (2675-2680m) having a VR of _0.4%Ro. The EqVR value, however, for the deepest sample is 0.70%. The maturity trend determined from the FAMM data (and VR data, omitting samples having suppressed VR) indicates that the top of the oil window (VR of 0.75%Ro) is located at about 2800m depth. Modelling the geothermal gradient using the EASY%Ro algorithm yields _40 1C/km for both of the two maturity profiles; his is in the low end of the range for the Malay Basin. Modelled temperature histories indicate onset of hydrocarbon generation for the uppermost Oligocene source rocks between 2Ma and present-day, which post-dates trap formation. Seismic facies patterns suggest that lacustrine oil-prone units are in he oil window in the same graben complex a few km NW of the investigated well, and these rocks are likely to be the source of the hydrocarbons found in the well. A more widespread occurrenceof hydrocarbons sourced from this kitchen is indicated by other discoveries and mapping of DHIs in the area.

  17. Vegetation and geomorphic significance of the riparian greenline in the Sprague River basin, southern Oregon: implications for biogeomorphic monitoring of riparian corridors in semi-arid mountain valleys

    Science.gov (United States)

    Hughes, M. L.; Leeseberg, C.

    2009-12-01

    Like many regions in the western U.S., valley-floor environments of the semi-arid Sprague River basin of southern Oregon are heavily irrigated and widely grazed by cattle. To better understand the impacts of grazing and other land uses on river quality, the Klamath Tribes have begun a long-term, basin-wide program aimed at: (1) establishing baseline geomorphic and vegetative conditions along the Sprague River and its tributaries, and (2) monitoring changes in these conditions over time. Because of its widespread use and ease of application, determining the composition of the lowest line of perennial vegetation above baseflow, or the “greenline,” has been included. The goal of this paper is to summarize results of 38 greenline surveys conducted at 19 sites in 2008-9 and to explore geomorphic hypotheses that may explain vegetation patterns evident in the surveys. Spikerush (Eleocharis ssp.) and reed-canary grass (Phalaris arudinacea) were the most commonly occurring vegetation in the greenline across all sites. Because these species are aggressive colonizers, they indicate high availability of fresh alluvium, which may be associated with sustained channel-bank disturbance. Sedges dominated some portions of the greenline at most of the sites, but occurred in less abundance. The late successional or early-to-late transitional state of these sedges, combined with their relatively low frequency, further supports the hypothesis that channel-bank systems remain chronically disturbed and dynamic. Grazing is common, but variable in intensity, at nearly all of the study sites, likely contributing to the persistence of channel-bank disturbance. Among meandering channels, the richness of dominant species (i.e., “community diversity”) was higher on the outer bends than on the inner bends of meanders at 10 of 12 sites. The variability of geomorphic surfaces (old floodplain, new floodplain, failed bank, accreted toe, etc.) incorporated in the greenline by the spatially discontinuous processes of channel-bank erosion and failure on the outer meander bends appears to increase the types of habitats surveyed and their combined biodiversity. In contrast, the spatial continuity of bar accretion on the inner meander bends appears to result in a more uniform geomorphic setting with fewer dominant species in the greenline. Despite widespread recognition that geomorphic processes influence riparian vegetation, factors such as the type and severity of bank erosion, the location of the survey with respect to meander geometry, and the type of geomorphic surface underlying greenline observations are not explicitly included in published guidance for biogeomorphic monitoring of the riparian greenline. Inclusion of such factors would improve communication, study design, and application of research by fluvial geomorphologists, riparian ecologists, and resource managers utilizing the greenline methodology.

  18. Population Structure and Genetic Diversity of the Endangered South American Giant Otter (Pteronura brasiliensis) from the Orinoco Basin in Colombia: Management Implications and Application to Current Conservation Programs.

    Science.gov (United States)

    Caballero, Susana; Correa-Cárdenas, Camilo A; Trujillo, Fernando

    2015-01-01

    Endangered giant otters, Pteronura brasiliensis, are found along the Amazon and Orinoco rivers and most of their tributaries. Hunting in the mid-1970s pushed giant otter populations to the brink of extinction. We studied population structure and genetic diversity of giant otters from Colombia's Orinoco basin using analyses of partial mitochondrial DNA control region sequences obtained from scat material. We collected and analyzed 54 scat samples from 22 latrines, 2 tissue samples primarily from captive giant otters and 2 from hunted animals near Puerto Carreño and Puerto Inírida (Colombian Orinoco), as well as one tissue sample from Puerto Leguizamo (Colombian Amazon). Thirty-nine partial control region sequences were obtained (258bp), corresponding to 15 unique haplotypes. Most of these haplotypes, found in samples collected around Puerto Carreño, defined one phylogeographic group (phylogroup) not previously described. Higher genetic diversity in the Colombian Orinoco populations than in other South American populations suggests that this newly described phylogroup, as well as a second phylogroup defined from a few Colombian Orinoco and Amazon samples, should be considered distinct genetic management units. National conservation programs, particularly those aiming to establish protected areas, should manage these independently. Current Colombian confiscated animal reintroduction and captive reproduction programs should also consider such differentiation when determining reintroduction locations or improving husbandry practices. PMID:26245782

  19. First record of petrified Permian pecopterids from the Paraná Basin, Brazil (Corumbataí Formation, Passa Dois Group, northeastern State of São Paulo): Morphology, anatomy and paleoecological implications

    Science.gov (United States)

    Tavares, Tatiane M. V.; Rohn, Rosemarie

    2009-02-01

    Petrified pecopterids are described for the first time in the Paraná Basin. They were collected at an outcrop of the Corumbataí Formation (Passa Dois Group, Middle Permian) in the Municipality of Piracicaba (State of São Paulo, Brazil). The assemblage is composed of Pecopteris taguaiensis Rohn and Rösler, 1986, Pecopteris sp. 1, Pecopteris sp. 2 and Pecopteris sp. 3. An emendation to the diagnosis of P. taguaiensis is proposed on the basis of the characteristics shown by the preserved three-dimensional external leaf morphology and partially by the epidermis (not available in the previously described impressions). The small size of the pinnules, the thick, downward-rolled leaf lamina, the thick veins, the straight walls of the epidermal cells, and the trichomes of the four pecopterid taxa may be interpreted as xeromorphic features developed in response to relatively dry climatic conditions and/or direct incidence of the sunlight. The leaves were impregnated with silica before the final burial, considering that they are fragmented, not deformed and associated with angular breccia clasts.

  20. Stable isotopic evidence for a Pre-Middle Miocene rain shadow in the western Basin and Range: Implications for the paleotopography of the Sierra Nevada

    Science.gov (United States)

    Poage, M. A.; Chamberlain, C. P.

    2002-08-01

    A recently proposed method for approximating the paleorelief of mountain belts makes use of the predictable relationship between the isotopic depletion of precipitation and the net elevation of an orographic barrier over which an air mass rises. This rain shadow effect often creates desert regions on the lee side of mountain belts in which precipitation is isotopically light. Changes in the isotopic composition of precipitation can be estimated from the isotopic composition of authigenic or pedogenic minerals, which can then be used to infer both the development of relief during orogenesis as well as the stability of a rain shadow formed by developing mountains. The ?18O of smectites formed from the weathering of Middle Miocene to Late Pliocene volcanic ashes currently exposed in the rain shadow of the modern Sierra Nevada of California show no indication of large-scale Late Cenozoic surface uplift of the Sierra and corresponding regional rain shadow development. Rather smectite isotope data tentatively suggest that elevations may have decreased over this time by as much as 2000 m toward the southern end of the range and 700 m in regions farther north. This suggests that the modern rain shadow cast over the western Basin and Range has been in existence since pre-Middle Miocene and that the Sierra Nevada have been a prominent orographic barrier since before this time. These interpretations are in accord with several recent studies also suggesting a possible Cenozoic elevation loss of an already developed Sierra Nevada mountain range.

  1. Hydrologic models of modern and fossil geothermal systems in the Great Basin: Genetic implications for epithermal Au-Ag and Carlin-type gold deposits

    Science.gov (United States)

    Person, M.; Banerjee, A.; Hofstra, A.; Sweetkind, D.; Gao, Y.

    2008-01-01

    The Great Basin region in the western United States contains active geothermal systems, large epithermal Au-Ag deposits, and world-class Carlin-type gold deposits. Temperature profiles, fluid inclusion studies, and isotopic evidence suggest that modern and fossil hydrothermal systems associated with gold mineralization share many common features, including the absence of a clear magmatic fluid source, discharge areas restricted to fault zones, and remarkably high temperatures (>200 ??C) at shallow depths (200-1500 m). While the plumbing of these systems varies, geochemical and isotopic data collected at the Dixie Valley and Beowawe geothermal systems suggest that fluid circulation along fault zones was relatively deep (>5 km) and comprised of relatively unexchanged Pleistocene meteoric water with small (modern and Tertiary hydrothermal systems of the Great Basin. Geologically and geophysically consistent cross sections were used to generate somewhat idealized hydrogeologic models for these systems that include the most important faults, aquifers, and confining units in their approximate configurations. Multiple constraints were used, including enthalpy, ??18O, silica compositions of fluids and/or rocks, groundwater residence times, fluid inclusion homogenization temperatures, and apatite fission track anomalies. Our results suggest that these hydrothermal systems were driven by natural thermal convection along anisotropic, subvertical faults connected in many cases at depth by permeable aquifers within favorable lithostratigraphic horizons. Those with minimal fluid ?? 18O shifts are restricted to high-permeability fault zones and relatively small-scale (???5 km), single-pass flow systems (e.g., Beowawe). Those with intermediate to large isotopic shifts (e.g., epithermal and Carlin-type Au) had larger-scale (???15 km) loop convection cells with a greater component of flow through marine sedimentary rocks at lower water/rock ratios and greater endowments of gold. Enthalpy calculations constrain the duration of Carlin-type gold systems to probably modern Beowawe system is <5 k.y. However, fluid flow at Beowawe during the Quaternary must have been episodic with a net duration of ???200 k.y. to account for the amount of silica in the sinter deposits. In the Carlin trend, fluid circulation extended down into Paleozoic siliciclastic rocks, which afforded more mixing with isotopically enriched higher enthalpy fluids. Computed fission track ages along the Carlin trend included the convective effects, and ranged between 91.6 and 35.3 Ma. Older fission track ages occurred in zones of groundwater recharge, and the younger ages occurred in discharge areas. This is largely consistent with fission track ages reported in recent studies. We found that either an amagmatic system with more permeable faults (10-11 m2) or a magmatic system with less permeable faults (10-13 m2) could account for the published isotopic and thermal data along the Carlin trend systems. Localized high heat flow beneath the Muleshoe fault was needed to match fl uid inclusion temperatures at Mule Canyon. However, both magmatic and amagmatic scenarios require the existence of deep, permeable faults to bring hot fluids to the near surface. ?? 2008 Geological Society of America.

  2. Magnetic mineral study of Holocene marine sediments from the Alfonso Basin, Gulf of California: implications for depositional environment and sediment sources

    Scientific Electronic Library Online (English)

    L, Pérez-Cruz; J, Urrutia-Fucugauchi.

    2009-09-01

    Full Text Available Se presentan los resultados del estudio de propiedades magnéticas en sedimentos marinos colectados en la Cuenca Alfonso en la Bahía de la Paz, los cuales se analizan en términos de las fuentes de aporte y el ambiente de depósito en el sur del Golfo de California durante el Holoceno. El control estra [...] tigráfico se basa en fechamientos de radiocarbono, que indican una edad para los sedimentos de fondo del núcleo de alrededor de 7597-7831 años cal. B.P. La señal magnética está dominada por minerales de grano fino de titanomagnetitas, los cuales provienen de las secuencias de tobas silícicas expuestas en la Bahía de la Paz. La mineralogía magnética es relativamente homogénea como lo indican las mediciones de propiedades de susceptibilidad magnética, magnetización remanente y coercitividad. Los ciclos de histéresis magnética indican la ocurrencia de componente paramagnéticas y los ciclos correspondientes después de la corrección paramagnética muestran ciclos que saturan en campos bajos y altos valores de magnetización de saturación. Las gráficas de discriminación de estado de dominio magnético empleando cocientes de los parámetros de histéresis muestran que las muestras se agrupan en el campo de dominio pseudos-sencillo, sugiriendo mezclas de dominios sencillo y múltiple. Los registros de susceptibilidad magnética revelan valores altos de factores de dependencia de frecuencia, en particular en el segmento del Holoceno Medio, lo que sugiere contribuciones de minerales superparamagnéticos de grano fino y posible transporte eólico. La presencia de laminaciones finas, características de la secuencia de Alfonso indica condiciones anóxicas en el fondo de la cuenca. El ambiente de depósito durante el Holoceno parece ser dominado por sedimentos detríticos pluviales y sedimentos de grano muy fino y transporte eólico, con menor contribución de sedimentos biogénicos. Abstract in english Results of a rock magnetic study of marine sediments from the Alfonso Basin, Bay of La Paz are used to investigate sediment sources and depositional environment in the southern Gulf of California during the Holocene. Radiocarbon dating provides stratigraphic control, with age for the core bottom sed [...] iments of 7597-7831 cal. yr B.P. Magnetic signal is dominated by fine-grained titanomagnetites, derived from the silicic volcanic units surrounding the Bay of La Paz. Magnetic mineralogy is relatively homogenous as seen in bulk magnetic properties of low-field susceptibility, remanent intensity and coercivity. Magnetic hysteresis loops show strong variable paramagnetic components; after paramagnetic correction loops show saturation at low fields and high saturation magnetization values. Plots of hysteresis parameter ratios for domain state show that samples group in the pseudo-single domain field, with mixtures of single and multi-domain particles. Magnetic susceptibility log shows relatively high frequency dependence factors, particularly for the Middle Holocene, suggesting contribution of fine-grained superparamagnetic minerals related to eolian deposition. The well-preserved laminated sequence indicates predominant anoxic conditions in the basin floor. Depositional environment had a dominant supply of pluvial detrital sediments and eolian fine-grained dust composed of siliciclastic volcanically-derived material with less abundant biogenic input.

  3. Complementing data-driven and physically-based approaches for predictive morphologic modeling: Results and implication from the Red River Basin, Vietnam

    Science.gov (United States)

    Schmitt, R. J.; Bernardi, D.; Bizzi, S.; Castelletti, A.; Soncini-Sessa, R.

    2013-12-01

    During the last 30 years, the delta of the Red River (Song Hong) in northern Vietnam experienced grave morphologic degradation processes which severely impact economic activities and endanger region-wide livelihoods. Rapidly progressing river bed incision, for example, threatens the irrigation of the delta's paddy rice crops which constitute 20% of Vietnam's annual rice production. Morphologic alteration is related to a drastically changed sediment balance due to major upstream impoundments, sediment mining and land use changes, further aggravated by changing hydro-meteorological conditions. Despite the severe impacts, river morphology was so far not included into the current efforts to optimize basin wide water resource planning for a lack of suitable, not overly resource demanding modeling strategies. This paper assesses the suitability of data-driven models to provide insights into complex hydromorphologic processes and to complement and enrich physically-based modeling strategies. Hence, to identify key drivers of morphological change while evaluating impacts of future socio-economic, management and climate scenarios on river morphology and the resulting effects on key social needs (e.g. water supply, energy production and flood mitigation). Most relevant drivers and time-scales for the considered processes (e.g. incision) - from days to decades - were identified from hydrologic and sedimentologic time-series using a feature ranking algorithm based on random trees. The feature ranking pointed out bimodal response characteristics, with important contributions of long-to-medium (5 - 15 yrs.) and rather short (10d - 6 months) timescales. An artificial neural network (ANN), built from identified variables, subsequently quantified in detail how these temporal components control long term trends, inter-seasonal fluctuations and day to day variations in morphologic processes. Whereas the general trajectory of incision relates, for example, to the overall regional sediment balance over an extended time-horizon (>15 yrs.), upstream impoundments induce a much more rapid adaptation (1-5 yrs.). The applicability of the ANN as predictive model was evaluated by comparing its results with a traditional, 1D bed evolution model. The next decade's morphologic evolution under an ensemble of scenarios, considering uncertainties in climatic change, socio-economic development and upstream reservoir release policies was derived from both models. The ANN greatly outperforms the 1D model in computational requirements and presents a powerful tool for effective assessment of scenario ensembles and quantification of uncertainties in river hydro-morphology. In contrast, the processes-based model provides detailed, spatio-temporally distributed outputs and validation of the ANN's results for selected scenarios. We conclude that the application of both approaches constitutes a mutually enriching strategy for modern, quantitative catchment management. We argue that physically based modeling can have specific spatial and temporal constrains (e.g. in terms of identifying key drivers and associated temporal and spatial domains) and that linking physically-based with data-driven approaches largely increases the potential for including hydro-morphology into basin-scale water resource management.

  4. Stable isotopic records from Cenozoic basins in the SE Margin of the Tibetan Plateau, Yunnan Province, China: implications for regional paleoelevation

    Science.gov (United States)

    Hoke, G. D.; Garzione, C. N.; Chen, L. G.

    2008-12-01

    We report the initial results of an ongoing stable isotope study of Cenozoic sediments from the northern part of China's Yunnan Province. The aim of this study is to constrain paleoelevations in this area in order to determine which geodynamic and/or climatic factors are responsible for the enigmatically gentle topographic gradient of this margin of the Tibetan Plateau and the formation of deeply incised canyons since the late Miocene. This work includes sampling small catchment area (<100 km2) tributaries of the Mekong river in ~100 m vertical increments from 500 m (near the Vietnam border) to 4000 m elevation (near Daqen), which we use to constrain the modern gradient in ?18O with elevation in this area. We measured detailed stratigraphic sections and collected samples of authigenic carbonates from the Paleogene-lower Miocene Jianchuan and the Upper Miocene Lanping Basins. A smaller number of samples come from exposures of Pliocene age rocks near the city of Weishan and village of Jin Bao Shan. We rely almost exclusively on the age assignments from Chinese geologic maps. The majority of our ?18O data from the sediments have ?18O values between -14 to -10 per mil (VPDB) from the pre-Miocene through the Pliocene. When compared to the modern elevation- dependent gradient in ?18O these data suggest that there has been < 500 m of elevation change in this area since the at least the early Miocene. If no significant Neogene elevation change has occurred on the SE Margin of the plateau, then incision was most likely driven by some other mechanism, perhaps climatic in nature.

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

    Science.gov (United States)

    Zhan, S.; Chen, Y.; Xu, B.; Wang, B.; Faure, M.

    2006-12-01

    In order to better constrain the Neoproterozoic paleogeographic reconstruction of continents and improve the understanding of the snowball Earth hypothesis, paleomagnetic collections on Neoproterozoic rocks were carried out in the Aksu area of the northwestern Tarim basin from 2001 to 2005. Six sites of limestone from the Chigebrak formation, 38 sites of sandstone and 4 sites of volcanic rocks from the Sugetbrak formation were sampled. The remaining 24 sites of sandstone and volcanic rocks reveal stable characteristic remanent component (ChRm) isolated from 500 to 680? The computed magnetic directions from these components are relatively consistent and significantly distinguished from those of younger ages. Both normal and reverse polarities have been observed though the normal one is dominant, moreover, the positive fold test is revealed after bedding corrections at 95% confidence level. A paleomagnetic pole is, therefore, calculated: l =19.1? f =149.7? k = 11.2, A95 = 9.3?with n = 24, yielding a paleolatitude of ~27 for the sampling area. The chemostratigraphic correlation of this section with reference ones reveals an average of ~595 Ma for the age for this collection. Comparing paleomagnetic data of the similar ages from Australia and South China as well as other major blocks, the Tarim block seemed being closely located in the north of Australia. A new paleogeographic reconstruction has been attempted which showing a general feature of lower paleolatitude for these blocks. Referring to the paleogeographic reconstruction at about 760Ma proposed by Chen et al. (2004), the continental landmass including the above mentioned blocks seemed having experienced a relatively slow southward kinematic drift and kept their rather low paleolatitude. These observations provide, therefore, evidences to the snowball Earth hypothesis in the late Neoproterozoic time.

  6. Organic geochemistry of the Callovo-Oxfordian argillo-carbonated sedimentary series of the East of the Paris basin and of England. Variabilities and paleo-environmental implications

    International Nuclear Information System (INIS)

    The Callovo-Oxfordian clay-stones from the East of the Paris basin are studied by ANDRA in order to test the feasibility of a possible storage of radioactive waste. The molecular analysis of their organic matter indicates that they can be considered as homogenous from their organic content point of view because they are characterized by only one molecular facies. However, the transition to the surrounding limestones is underlined by a major evolution of the molecular facies indicating a change and an increase of the variability of the deposition and diagenesis conditions. The evolution of the distribution of the plant bio-markers indicates, at the end of the Lower Oxfordian, a paleo-floristic change characterized by the increase of the proportion of Pinaceae (a conifer family) or their forerunners on the London-Brabant massif. This paleo-floristic evolution reflects a paleo-climatic change characterized by the increase of aridity at the global scale. Other complementary results get on other sedimentary series of similar ages highlight the occurrence of a period of water anoxia during the Middle Callovian which certainly happened on the major part of the Western Europe. This event could be at the origin of the crisis of the carbonate production at the Dogger/Malm transition. On the other hand, an experimental technique based on artificial maturation of extant plants has been developed and will allow the acquisition of new palaeo-chemo-taxonomic data. These data will contribute to a better interpretation of plant bio-marker assemblages in terms of palaeo-floristic composition. (author)

  7. Subsurface geology of the Warfield structures in southwestern West Virginia: Implications for tectonic deformation and hydrocarbon exploration in the Central Appalachian basin

    Energy Technology Data Exchange (ETDEWEB)

    Gao, D. [Duke Univ., Durham, NC (United States); Shumaker, R.C. [West Virginia Univ., Morgantown (United States)

    1996-08-01

    Data from over 6000 wells and five multichannel reflection seismic lines were used to constrain the subsurface geometry of the Warfield structures in southwestern West Virginia within the central Appalachian basin. Based on their vertical differences in geometry and structural styles, we divided the Warfield structures into shallow (above the Devonian Onondaga Limestone), intermediate (between the Devonian Onondaga Limestone and the Silurian Tuscarora Sandstone), and deep (below the Ordovician Trenton horizon) structural levels. Shallow structures are related to the Alleghanian deformation above the major detachment horizon of the Devonian shales and consist of the Warfield anticline with a 91.5-m closure and southeast-dipping monoclines, which aided the northwest migration and entrapment of oil and gas. At the intermediate level, the closure of the Warfield anticline is lost because the Alleghanian deformation is obscured below the major detachment of the Devonian shales, which explains the reduced production from the Devonian and Silurian reservoirs. Deep structures are characterized by an asymmetric half graben within a continental rift system known as the Rome trough, in which a thick sequence of sedimentary rocks exists to provide sources for overlying reservoirs. Although stratigraphic traps may be associated with thickness and facies changes, the deep level is structurally unfavorable for trapping hydrocarbons. Based on changes we found in map trend, we divided the Warfield structures into a middle segment and southern and northern bends. The middle segment is parallel to the New York-Alabama lineament (a northeast-trending magnetic gradient); the southern and the northern bends are linked to the 38th parallel lineament (a west-trending fault system) and the Burning Springs-Mann Mountain lineament (a north-trending magnetic gradient), respectively.

  8. Quantifying water requirements of riparian river red gum (Eucalyptus camaldulensis) in the Murray-Darling Basin, Australia: implications for the management of environmental flows

    Science.gov (United States)

    Doody, Tanya M.; Colloff, Matthew J.; Davies, Micah; Koul, Vijay; Benyon, Richard G.; Nagler, Pamela L.

    2015-01-01

    Water resource development and drought have altered river flow regimes, increasing average flood return intervals across floodplains in the Murray-Darling Basin, Australia, causing health declines in riparian river red gum (Eucalyptus camaldulensis) forests and woodlands. Environmental flow allocations helped to alleviate water stress during the recent Millennium Drought (1997–2010), however, quantification of the flood frequency required to support healthy E. camaldulensis communities is still needed. We quantified water requirements of E. camaldulensis for two years across a flood gradient (trees inundated at frequencies of 1:2, 1:5 and 1:10 years) at Yanga National Park, New South Wales to help inform management decision-making and design of environmental flows. Sap flow, evaporative losses and soil moisture measurements were used to determine transpiration, evapotranspiration and plant-available soil water before and after flooding. A formula was developed using plant-available soil water post-flooding and average annual rainfall, to estimate maintenance time of soil water reserves in each flood frequency zone. Results indicated that soil water reserves could sustain 1:2 and 1:5 trees for 15 months and six years, respectively. Trees regulated their transpiration rates, allowing them to persist within their flood frequency zone, and showed reduction in active sapwood area and transpiration rates when flood frequencies exceeded 1:2 years. A leaf area index of 0.5 was identified as a potential threshold indicator of severe drought stress. Our results suggest environmental water managers may have greater flexibility to adaptively manage floodplains in order to sustain E. camaldulensis forests and woodlands than has been appreciated hitherto.

  9. The optical properties of river and floodplain waters in the Amazon River Basin: Implications for satellite-based measurements of suspended particulate matter

    Science.gov (United States)

    Martinez, Jean-Michel; Espinoza-Villar, Raul; Armijos, Elisa; Silva Moreira, Luciane

    2015-07-01

    Satellite images can now be used to assess river sediment discharge, and systematic studies over rivers and lakes are required to support such applications and document the variability of inland water optical properties at the watershed scale. The optical properties of the Amazon Basin waters were analyzed from in situ measurements of the remote sensing reflectance (Rrs) at 279 stations and downwelling diffuse attenuation coefficients (Kd) at 133 stations. Measurements of the apparent optical properties, suspended particulate matter (SPM) contents, and characteristics and colored dissolved organic matter (CDOM) absorption spectra were performed during 16 cruises along the main Amazonian Rivers draining the Andes and for some tributaries. Surface-suspended sediment granulometry and mineralogy showed a stable distribution at the catchment scale, even over large distances and between tributaries. The particle number-size distribution was best described using a segmented distribution with a slope of 2.2 for the fine range (1-15 µm), and the CDOM absorption coefficient at 440 nm varied from 1.8 to 7.9 m-1. Overall, both Rrs and Kd were strongly correlated with SPM, although strong CDOM absorption limited the use of the blue spectrum. Reflectance saturation from blue to red was observed at approximately 100 g m-3, whereas the near-infrared (NIR) wavelength enabled the monitoring of the full SPM range (5-620 g m-3). In contrast, Kd showed no saturation for SPM from green to NIR, and a linear model was calculated. The use of the reflectance ratio was investigated and shown to improve the suspended sediment concentration retrieval performance.

  10. Assessing the implications of water harvesting intensification on upstream-downstream ecosystem services: A case study in the Lake Tana basin.

    Science.gov (United States)

    Dile, Yihun Taddele; Karlberg, Louise; Daggupati, Prasad; Srinivasan, Raghavan; Wiberg, David; Rockström, Johan

    2016-01-15

    Water harvesting systems have improved productivity in various regions in sub-Saharan Africa. Similarly, they can help retain water in landscapes, build resilience against droughts and dry spells, and thereby contribute to sustainable agricultural intensification. However, there is no strong empirical evidence that shows the effects of intensification of water harvesting on upstream-downstream social-ecological systems at a landscape scale. In this paper we develop a decision support system (DSS) for locating and sizing water harvesting ponds in a hydrological model, which enables assessments of water harvesting intensification on upstream-downstream ecosystem services in meso-scale watersheds. The DSS was used with the Soil and Water Assessment Tool (SWAT) for a case-study area located in the Lake Tana basin, Ethiopia. We found that supplementary irrigation in combination with nutrient application increased simulated teff (Eragrostis tef, staple crop in Ethiopia) production up to three times, compared to the current practice. Moreover, after supplemental irrigation of teff, the excess water was used for dry season onion production of 7.66t/ha (median). Water harvesting, therefore, can play an important role in increasing local- to regional-scale food security through increased and more stable food production and generation of extra income from the sale of cash crops. The annual total irrigation water consumption was ~4%-30% of the annual water yield from the entire watershed. In general, water harvesting resulted in a reduction in peak flows and an increase in low flows. Water harvesting substantially reduced sediment yield leaving the watershed. The beneficiaries of water harvesting ponds may benefit from increases in agricultural production. The downstream social-ecological systems may benefit from reduced food prices, reduced flooding damages, and reduced sediment influxes, as well as enhancements in low flows and water quality. The benefits of water harvesting warrant economic feasibility studies and detailed analyses of its ecological impacts. PMID:26519564

  11. Vinna Basin.

    Czech Academy of Sciences Publication Activity Database

    Hon?k, J.; Franc?, J.; Mikuláš, Radek; Pešek, J.; Sýkorová, Ivana; Tomanová-Petrová, P.

    Prague : Czech Geological Survey, 2014, s. 223-241 ISBN 978-80-7075-862-5 R&D Projects: GA ?R GA105/06/0653 Institutional support: RVO:67985891 ; RVO:67985831 Keywords : Tertiary basins * Czech Republic * Cenomanian and Tertiary lignite * geology * stratigraphy Subject RIV: DB - Geology ; Mineralogy

  12. Gravity anomaly across the Yap Trench, Sorol Trough, and southernmost Parece Vela Basin and its implications for the flexural deformation of the lithosphere and regional isostasy

    Science.gov (United States)

    Kim, Y.; Lee, S.; Okino, K.; Koizumi, K.

    2005-12-01

    In June 2005, R/V Hakuho-maru (KH05-01-Leg 3) conducted a geological and geophysical survey of the southern tip of the Parece Vela Basin (PVB). The survey also profiled the Yap trench, the Yap arc and back-arc region, and Sorol Trough and collected multibeam bathymetry, gravity and magnetic data. In addition, one multichannel seismic reflection profiling across the Yap trench and two dredge rock samplings in the southwestern PVB were carried out. The shipboard free-air gravity field was measured by ZLS Dynamic Gravity Meter D-004 with calibration ties performed at Ocean Research Institute, University of Tokyo and at Apra Harbor in Guam. The shipboard gravity anomaly data show clear match with those derived from satellite altimetry. Also included in our analysis is the shipboard gravity data previously collected by R/V Onnuri. The Yap trench is unique in that it has a short trench-arc distance (approx. 50 km). This proximity has long been interpreted as feature resulting from a collision of over-thickened Caroline Ridge with the trench. In recent years, however, a new hypothesis has been put forward that such feature can be explained by initiation or rejuvenation of subduction, and that the style of subduction changes between north and south of the Sorol Trough. Our survey also revealed peculiar hook-shaped structures in the southernmost PVB and other evidences for large-scale, complex rotational deformation on the seafloor, whose origin remains unclear at this stage. To better understand the nature of these structures and features across Yap trench, Sorol Trough and in southernmost PVB, we examine the regional isostasy using the recently collected bathymetric and gravity data. The density information is deduced from studies conducted at other subduction systems, including Izu-Bonin Mariana trench, and from our own seismic experiment. Preliminary analysis shows that much of the features may be maintained by the flexural rigidity of the lithosphere, especially near and along the trench. To assess the significance of flexural strength of the crust, we apply various flexural models and see if they can explain the observed bathymetry and gravity. The results of this study may provide new clues that will help us to understand the overall tectonic framework of the region at the boundary between two plates, the Philippine Sea and Caroline plates, and their past interaction.

  13. Small-scale sedimentary structures and their implications in recognizing large-scale ancient tidal bedforms. Example from Dur At Talah outcrop, Late Eocene, Sirt Basin, Libya

    Science.gov (United States)

    Abouessa, Ashour; Duringer, Philippe; Schuster, Mathieu; Pelletier, Jonathan; Rubino, Jean-Loup

    2014-12-01

    The Dur At Talah escarpment (150 m thick and 150 km long) is exposed at the southern side of the Sirt Basin, central Libya. This outcrop exposes an Upper Eocene succession, composed by highly bioturbated fine grained sandstones to claystones at the base (New Idam Unit; 80-100 m thick), overlain by medium grained to microconglomeratic sandstones at the top (Sarir Unit; 60 m thick). The latter is split into two subunits of nearly equal thickness: the lower Sarir subunit, composed of medium to coarse cross-bedded sandstones; and the upper Sarir subunit, composed of very coarse to microconglomeratic sandstones. The whole succession evolves from shallow marine estuarine (the New Idam Unit) to fluvial deposits (the upper Sarir subunit). The sandstone of the lower Sarir subunit, which is the focus of this article, is previously misinterpreted as being deposited in a purely fluvial environment. However, close observations revealed that the depositional environment is largely tide-influenced. It is notably marked by conspicuous subaqueous dune cross-stratifications that bear a variety of discrete, multi-scale, sedimentary structures evidencing their deposition in tidal rather than fluvial setting. Mud drapes, tidal bundles, and perpendicularly draining and oppositely climbing ripples are largely developed. Among these structures, the most diagnostic are of millimetric to centimetric scale. As a prime aim of this article, all these sedimentary structures are described, interpreted, and discussed for the first time from this outcrop. Their style of association and the quality of their preservation provide an outstanding ancient example of tide-dominated siliciclastic systems. Such structures are rarely found together in one outcrop as they are in Dur At Talah, and they provide a significant indicators in identifying ancient bedforms of tidal origin. Evidences of subtidal and intertidal depositional environments are afforded by these structures. Criteria indicative of semidiurnal regime of the tide are also presented. These criteria are especially well-preserved in the bundled foresets of the spring tides, the neap tide record is also distinguishable but it provides no discernible structures. Moreover, sedimentary features that can be used to infer a macrotidal range during the depositional time are also afforded by a combination of these structures. Above all, this study also concludes that one of the most reliable sedimentary structures for recognizing the tidal bedforms are the ripple-scale (centimetric) sedimentary structures. These are preserved inside and at the base of the cross-sets.

  14. Residual basins

    International Nuclear Information System (INIS)

    Exploration for uranium carried out over a major portion of the Rio Grande do Sul Shield has revealed a number of small residual basins developed along glacially eroded channels of pre-Permian age. Mineralization of uranium occurs in two distinct sedimentary units. The lower unit consists of rhythmites overlain by a sequence of black shales, siltstones and coal seams, while the upper one is dominated by sandstones of probable fluvial origin. (Author)

  15. Morphometric Analysis of Martian Valley Network Basins

    Science.gov (United States)

    Luo, W.; Arvidson, R. E.; Howard, A. D.

    2005-05-01

    Whether the Martian valley networks were formed predominantly by groundwater sapping or surface fluvial runoff continues to be debated and has profoundly different implications for the climatic history of Mars and the possible evolution of life there. This paper attempts to evaluate the relative role of groundwater sapping vs. surface runoff in valley networks generation through quantitative morphometic analysis at watershed basin scale using the highest resolution MOLA DEM data. Treating the hypsometric curve of each basin as a cumulative probability distribution, its integral, skewness, kurtosis, density skewness, and density kurtosis (collectively called hypsometric attributes) can serve as quantitative measures of the basin's morphology. The hypsometric attributes are sensitive to variations in overall basin characteristics and thus are diagnostic of possible processes. These attributes of typical terrestrial sapping basins, typical terrestrial fluvial basins, and typical lunar impact cratering basins were used as endmembers to establish discriminant functions to classify Martian basins. The posteriori probability of each class membership for each Martian basin then serves as the measure of the relative role of sapping, fluvial or cratering process in forming that basin. Initial results in Margaritifer Sinus area show that groundwater sapping played a more dominant role than surface runoff, generally consistent with previous findings based on lower resolution data and supporting a precipitation-recharged groundwater sapping origin for valley networks. Using a circularity function (a ratio of area and perimeter as a function of elevation) as the measure for basin morphology in the discriminant analysis produced similar results. Other traditional morphometric parameters such as drainage density, width function, cumulative area distribution, and slope-area relationship will also be derived for Margaritifer and other areas. The overall spatial pattern of the distribution will be examined to shed more light on past climatic conditions for generating the Martian valley networks.

  16. Advancing Methods for Hydrogeological Characterization of Deep Aquifers in Sedimentary Basins

    Science.gov (United States)

    Singh, A.; Palombi, D.

    2014-12-01

    The Groundwater Program at the Alberta Geological Survey is focused on identifying, characterizing and quantifying Alberta's groundwater resources. Characterization of deep groundwater resources is becoming increasingly important as the Government of Alberta implements its Water Conservation Policy seeking to minimize freshwater use. Conducting an inventory of saline water (non-traditional) resources for source water in various energy development scenarios, at basin scales, pose significant challenges given the potential competing uses and demand for groundwater resources. Current research activities are seeking to improve our methods to characterize deep aquifers in data-rich sedimentary basins. Two methods are discussed here: 1) identifying production/injection influenced Drill Stem Test (DST) measurements for mapping distributions of hydraulic heads (both present-day and prior to development) in deep units; and 2) analyzing variable density flow effects. DSTs are transient pressure tests usually performed for assessing potential oil and gas productivity. These tests measure pressures using gauges at the surface and down-hole. The measured pressures can be strongly influenced in cases where the test interval is located in the vicinity of a production or injection well, which generally happens in mature sedimentary basins such as the Alberta basin. To identify production influences this study utilized a cumulative inference index (CII) based approach. A new application was developed in C-code to implement the CII and will be demonstrated on a sample DST dataset from the Western Canada Sedimentary Basin. Fluid flow in sedimentary basins is often inferred using freshwater hydraulic heads, reference formation water densities and pressure-depth plots. Previous studies in the Alberta basin have often neglected density variations. Effects of density driven flow needs to be taken into account in cases where dense brines are present, a large aquifer dip or small hydraulic gradients exist. This study implemented a vectoral analysis to identify flow directions in regions where density driven flow is important and can change the inferred magnitude and direction of flow. A python based script has been developed and will be demonstrated on a sample dataset from the Williston basin.

  17. Biological data for 10-20 streams in Salmon River Basin (Importance of biotic and abiotic features of salmon habitat implications for juvenile Chinook and steelhead growth and survival)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This is a large-scale, long-term comparative study that includes many streams (20+ streams in the Salmon River Basin, Idaho, including a few non-salmon streams for...

  18. High Resolution Audiomagnetotelluric Investigation of the Porosity at the Margin of the Hudson Bay Basin, Canada

    Science.gov (United States)

    Craven, J. A.; Roberts, B.

    2012-12-01

    Seismic exploration from 1968 to 1985 within the intracratonic Hudson Bay basin in northern Canada resulted in five dry wells drilled on a structural high in the central part of the basin (Hamblin, 2008). Recent work (Bertrand and Malo, 2012) has indicated successions at margins of the basin are well within the oil and gas "window". To test this conjecture a magnetotelluric (MT) survey was carried out in the vicinity of Churchill, Manitoba, at the margin of the basin. The primary goal of the survey was to identify potential source or reservoir rocks in the Upper Ordovician section of the Palaeozoic strata. MT surveys have been utilized in the northeastern portion of the Williston basin and have successfully imaged lower Palaeozoic carbonate units (Gowan et al., 2009). The MT method provides information on the electrical conductivity of the subsurface though the measurement of the natural time-varying electric and magnetic fields at the surface. Due to the dependence of the depth of investigation of the fields on their frequency, an estimate of conductivity variation with depth can be attained. A total of 46 high frequency audio-magnetotelluric (AMT) sites were collected, 38 along one approximately N-S corridor perpendicular to the coastline and 8 in a more E-W direction closer to the town of Churchill. Simultaneous collection of broadband MT data (BBMT) at a limited number of sites was done in order to calculate a response function over a wider range of frequencies at each AMT site. The combined AMT and BBMT MT data have been edited and processed to produce response functions at all sites, and 1-D modelling has provided resistivity vs. depth curves in the top 200 m of the basin. The 1-D models have been stitched together to create a continuous, approximately N-S resistivity section. In addition, the data have been input to a 3D inversion program and preliminary 3D resistivity and conductivity volumes have been generated along with an estimate of 3-D porosity variations to a depth of approximately 200 m.

  19. 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.

  20. Implicaciones hidrológicas del cambio de la cobertura vegetal y uso del suelo: una propuesta de análisis espacial a nivel regional en la cuenca cerrada del lago de Cuitzeo, Michoacán / Hydrological implications of land-cover and land-use change: a proposal for spatial analysis at a regional level in the closed Cuitzeo-lake basin, Michoacán

    Scientific Electronic Library Online (English)

    Manuel, Mendoza; Gerardo, Bocco; Erna, López Granados; Miguel, Bravo.

    2002-12-01

    Full Text Available Este estudio intenta contribuir en la comprensión de las implicaciones del cambio de la cobertura vegetal y uso del suelo (CCVUS) a nivel regional en el balance hídrico espacialmente distribuido (BHED) en una cuenca poco aforada para 1975 y 2000. Los resultados de esta investigación son producto de [...] la integración de herramientas de percepción remota y sistemas de información geográfica con un modelo de balance de agua; además, se utilizaron técnicas de análisis de dinámica de cambio. El análisis del cambio de los componentes del BHED a nivel de formas de relieve y por matrices de transición determinó que durante el periodo de estudio las condiciones hidrológicas regionales de la cuenca no se modificaron sustancialmente Sin embargo, las planicies y los piedemontes mostraron un incremento en los valores de escorrentia, como resultado de un incremento de la superficie ocupada por asentamientos humanos En ambos años, las formas de relieve de las zonas bajas de la cuenca mostraron fuerte presión sobre el recurso hídrico, lo cual repercute en el deterioro del lago de Cuitzeo, principalmente por contaminación y reducción del suministro de agua superficial al vaso. El enfoque integral utilizado puede representar una alternativa viable para entender el cambio en la distribución y cantidad del agua disponible en cuencas poco aforadas como resultado de un CCVUS. Abstract in english This study was undertaken to understand the implications of regional land-cover and land-use change ILCLUC) in a spatially distributed water balance (SDWB) within a poorly gauged basin in 1975 and 2000. Results from this work were derived by integrating remote sensing and geographic information syst [...] em tools with a water-balance model, along with the application of a transitional matrix analysis. The analysis of changes in water-balance components, based on landforms and transitional matrices, Indicated a small tendency towards improvement in the basin s hydrological conditions at a regional level However, as a consequence of the increase in urban land-use. The basin's plains piedmonts showed a rise in runoff. In addition, the basins' lower areas exhibited a high demand for water resources due to an increased urban land-use in both years, along with the Cuitzeo lake degradation, particularly in terms of pollution and reduction of surface water inflow. The integrated approach used herein constitutes a viable alternative for understanding changes in the amount and spatial distribution of water available in poorly gauged water basins as a consequence of LCLUC.

  1. 40Ar/ 39Ar ages of mafic dykes from the Mesoproterozoic Chhattisgarh basin, Bastar craton, Central India: Implication for the origin and spatial extent of the Deccan Large Igneous Province

    Science.gov (United States)

    Rao, N. V. Chalapathi; Burgess, R.; Lehmann, B.; Mainkar, D.; Pande, S. K.; Hari, K. R.; Bodhankar, N.

    2011-08-01

    We present 40Ar/ 39Ar whole-rock ages of 63.7 ± 2.7 Ma (2?, 92% Ar release) and 66.6 ± 2.2 Ma (2?, 96% Ar release) for two samples of sub-surface mafic dykes intrusive into the sedimentary rocks of the Mesoproterozoic Chhattisgarh basin, Bastar craton, Central India. The obtained ages are synchronous with those of the Deccan Traps whose nearest exposures are at a distance of ~ 200 km to the west, and the recently dated diamondiferous orangeites (Group-II kimberlites) of the Mainpur area (located ~ 100 km SE within the Bastar craton). The chemical composition of the Chhattisgarh mafic dykes is indistinguishable from the chemostratigraphic horizons of the upper Deccan lavas of the Wai Subgroup (Ambenali and Poladpur Formations) and confirms them to be a part of the Deccan Large Igneous Province (LIP). The geological setting of the Deccan-age mafic dykes in the Chhattisgarh basin is analogous to that observed in other LIPs of the world such as (i) Pasco Basin of NW U.S.A, (ii) Ellisras sub-basin of southern Africa, (iii) Rift basins of New England in the NE U.S.A and (iv) the West Siberian Basin of Russia where LIP-related basalts and sills have been emplaced in distant domains from the main province. The Deccan-age of the Chhattisgarh dykes and the Mainpur orangeites permits a substantial increase of at least 8.5 × 10 4 km 2 in the spatial extent of the Deccan LIP. The temporal link at ~ 65 Ma between the Deccan Traps and (i) sub-surface mafic dykes within the Chhattisgarh basin and orangeites in the Bastar craton, (ii) Ambadongar carbonatite in western India, (iii) Salma mafic dyke in the Eastern Indian craton, (iv) Rajahmundry Traps off the eastern coast of southern India and (v) tholeiitic dykes and basalts from the Seychelles, suggests a common tectonomagmatic control, via a vast mantle plume-head of the order of 2000-2500 km. Our study has relevance to the (i) origin (plume vs non-plume) of the Deccan LIP, (ii) plumbing system for Deccan dykes and lavas in domains far away from the presently exposed Trap regions, (iii) palaeo-environmental issues at the K-T boundary and (iv) metallogeny (diamond, Ni-Cu-PGE) in the Bastar craton.

  2. Tectonic and thermal history of the western Serrania del Interior foreland fold and thrust belt and Guarico Basin, north central Venezuela: Implications of new apatite fission track analysis and seismic interpretation

    Science.gov (United States)

    Perez de Armas, Jaime Gonzalo

    Structural analysis, interpretation of seismic reflection lines, and apatite fission-track analysis in the Western Serrania del Interior fold and thrust belt and in the Guarico basin of north-central Venezuela indicate that the area underwent Mesozoic and Tertiary-to-Recent deformation. Mesozoic deformation, related to the breakup of Pangea, resulted in the formation of the Espino graben in the southernmost portion of the Guarico basin and in the formation of the Proto-Caribbean lithosphere between the diverging North and South American plates. The northern margin of Venezuela became a northward facing passive margin. Minor normal faults formed in the Guarico basin. The most intense deformation took place in the Neogene when the Leeward Antilles volcanic island arc collided obliquely with South America. The inception of the basal foredeep unconformity in the Late Eocene-Early Oligocene marks the formation of a perisutural basin on top of a buried graben system. It is coeval with minor extension and possible reactivation of Cretaceous normal faults in the Guarico basin. It marks the deepening of the foredeep. Cooling ages derived from apatite fission-tracks suggest that the obduction of the fold and thrust belt in the study area occurred in the Late Oligocene through the Middle Miocene. Field data and seismic interpretations suggest also that contractional deformation began during the Neogene, and specifically during the Miocene. The most surprising results of the detrital apatite fission-track study are the ages acquired in the sedimentary rocks of the easternmost part of the study area in the foreland fold and thrust belt. They indicate an Eocene thermal event. This event may be related to the Eocene NW-SE convergence of the North and South American plates that must have caused the Proto-Caribbean lithosphere to be shortened. This event is not related to the collision of the arc with South America, as the arc was far to the west during the Eocene.

  3. Nouvelles données biostratigraphiques et sédimentologiques des formations carbonifères de la région de Bouqachmir (Maroc central). Implications sur la paléogéographie des bassins carbonifères nord-mésétiensNew biostratigraphic and sedimentological data of the Carboniferous formations in the Bouqachmir area (central Morocco). Implications on the palaeogeography of the north Mesetian Carboniferous basins

    Science.gov (United States)

    Izart, Alain; Tahiri, Abdelfatah; El Boursoumi, Abdou; Vachard, Daniel; Saidi, Mariam; Chèvremont, Philippe; Berkhli, Mostafa

    2001-02-01

    New Visean formations and biozones of foraminifera were defined on the Bouqachmir map. The new biozonation concerns the Moroccan biozone, Cfm1, which is subdivided into two subzones, Cfm1a and Cfm1b. This map exhibited, from north-west to south-east, the Tilouine, Bouqachmir-Tougouroulmès and Fourhal turbiditic basins. The first one, from Tournaisian to Late Visean, was the equivalent of the Sidi Bettache basin, located westwards. The second extended the Tilouine basin eastwards during the Visean. The third was a basin from Visean to Westphalian. They were separated by the Zaer-Oulmes and El Hammam horsts, else emerged or immersed, bordered by faults and with materials feeding chaotic deposits.

  4. Post-Laramide and pre-Basin and Range deformation and implications for Paleogene (55-25 Ma) volcanism in central Mexico: A geological basis for a volcano-tectonic stress model

    Science.gov (United States)

    Tristán-González, Margarito; Aguirre-Díaz, Gerardo J.; Labarthe-Hernández, Guillermo; Torres-Hernández, José Ramón; Bellon, Hervé

    2009-06-01

    At central-eastern Mexico, in the Mesa Central province, there are several ranges that were formed after the K/T Laramide compression but before the Basin and Range peak extensional episodes at middle-late Oligocene. Two important volcano-tectonic events happened during this time interval, 1) uplift of crustal blocks exhuming the Triassic-Jurassic metamorphic sequence and formation of basins that were filled with red beds and volcanic sequences, and 2) normal faulting and tilting to the NE of these blocks and fanglomerate filling of graben and half-graben structures. The first event, from late Paleocene to early Eocene, was related to NNE and NNW oriented dextral strike-slip faults. These faults were combined with NW-SE en echelon faulting in these blocks through which plutonism and volcanism occurred. The second event lasted from early Oligocene to early Miocene and coincided with Basin and Range extension. Intense volcanic activity occurred synchronously with the newly-formed or reactivated old fault systems, producing thick sequences of silicic pyroclastic rocks and large domes. Volcano-tectonic peaks occurred in three main episodes during the middle-late Oligocene in this part of Mexico, at about 32-30 Ma, 30-28 Ma, and 26-25 Ma. The objectives of this work is to summarize the volcano-tectonic events that occurred after the end of the Laramide orogeny and before the peak episodes of Basin and Range faulting and Sierra Madre Occidental Oligocene volcanism, and to discuss the influence of these events on the following Oligocene-Miocene volcano-tectonic peak episodes that formed the voluminous silicic volcanism in the Mesa Central, and hence, in the Sierra Madre Occidental. A model based upon geological observations summarizes the volcanic-tectonic evolution of this part of Mexico from the late Paleocene to the Early Miocene.

  5. THERMAL MATURITY HISTORY AND IMPLICATIONS FOR HYDROCARBON EXPLORATION IN THE CATATUMBO BASIN, COLOMBIA Historia de la madurez térmica e implicaciones para la exploración de hidrocarburos en la cuenca del Catatumbo, Colombia

    OpenAIRE

    Antonio Rangel; Roberto Hernández

    2007-01-01

    A thermal model integrated with an oil and gas geochemical study has been constructed for the Catatumbo Basin, Colombia to provide petroleum system data for hydrocarbon exploration. The calibration of the thermal model with maturity data took into account a changing heat flow scheme which included a thermal increase towards the end of the Jurassic and another one in the Early Eocene, associated with rifting events. Locally, active/generating source rocks are within the synclines axes. The hyd...

  6. Establishment of Chinook salmon (Oncorhynchus tshawytscha) in Pacific basins of southern South America and its potential ecosystem implications Establecimiento del salmón Chinook (Oncorhynchus tshawytscha) en cuencas del Pacífico sur de Sudamérica y sus potenciales implicancias ecosistémicas

    OpenAIRE

    DORIS SOTO; IVÁN ARISMENDI; CECILIA DI PRINZIO; FERNANDO JARA

    2007-01-01

    Salmon and trout species are not native to the southern hemisphere, however rainbow and brown trout have been established a century in southern South America. Yet most attempts to introduce anadromous salmon failed until the onset of aquaculture by 1980. Escapes of Oncorhynchus tshawytscha (Chinook salmon) from aquaculture after 1990 have apparently produced increasingly important reproductive returns "naturalized", to upper basins in Chile and Argentina south of 39º S. In this paper we show ...

  7. Climatic and tectonic feedbacks and implications on sedimentation, tectonic deformation, and erosion circa 3.1 Ma in the Qaidam Basin, China: Evidence from magnetostratigaphy, geochemistry, and stratigraphic analysis

    Science.gov (United States)

    Heermance, R.; Pullen, A.; Kapp, P. A.; Song, P.

    2011-12-01

    Understanding the feedbacks between tectonic deformation and climate change have been the focus of recent research in the earth sciences, especially related to development of the Tibetan-Qinghai plateau. Differentiating between the causal effect of climate change or tectonic deformation on one another, however, has been hindered by the lack of detailed chronology of either mechanism at any one location. The Qaidam Basin is an internally drained basin located in the NE corner of the Tibet-Qinghai Plateau, and provides an ideal setting to interpret both the effects of climate and tectonics within inverted basin strata. Today over 50% of the basin floor is deformed by folding and faulting, and has exposed thick (>1 km) sections of pre-and-syn-tectonic Plio-Quaternary strata. We present new magnetostratigraphy from the Pliocene Shizigou and Pleistocene Qigequan Formations along the southwestern flank of an intra-basin fold and combine our new data with detailed stratigraphic and geochemical (?18O, ?13C) analyses. Strata are characterized by shallow-lacustrine, marginal-lacustrine, and deltaic sediments that contain meter-scale, climatically controlled parasequences. Paleocurrents within the strata shift from easterly at the base to southwest for the majority of the section, but abruptly shift towards the south in the upper 200 m. Twenty-two magnetozones constrain deposition between 5.3 Ma and ~0.5 Ma and reveal that sedimentation rates were fairly constant (450±50 mm/yr) from 5.3 to 3.0 Ma, after which time rates abruptly decrease to 170±30 mm/yr. The ?18O values shift from relatively constant (avg. -6.8, range -9.6 to -4.5 VPDB) values to less negative values (avg. -1.2, range -1.2 to -2.7 VPDB) between 3.1-2.6 Ma and to widely scattered values (avg. -2.9, range -8.3 to 4.0) after ~2.6 Ma. The ?13C values remain relatively constant (avg. -4.0, range -5.7 to -1.0) until ~0.9 Ma, when the values increase to -0.3 (range -1.0 to 1.5) VPDB. The appearance of growth strata at 3.0 Ma, a sharp lithofacies change (Formation boundary) to shallow and sub-areal conditions by 2.6 Ma, and the observation of paleoyardangs (buried, wind-sculpted landforms) within lake-marginal strata at 2.4 Ma, imply that emergence of the adjacent anticline was followed by the shallowing or narrowing of the lake basin and sub-aerial exposure and erosion of marginal lake sediments. Together, these data imply an abrupt change in climate between 3.1 Ma and ~2.6 Ma, just prior to the onset of northern hemisphere glaciations. This abrupt change caused a shift in lake geochemistry, reduced sedimentation rates, aeolian erosion of lake-marginal sediments, and paleosol development. Tectonic inversion and enhanced aridification after 2.6 Ma provided a fertile environment for the wind deflation of the Qaidam Basin and provides a likely sediment source for the Chinese Loess Plateau at that time.

  8. The Heidelberg Basin Drilling Project — basin analysis

    Science.gov (United States)

    Tanner, David C.; Martini, Nicole; Buness, Hermann; Gabriel, Gerald; Krawczyk, Charlotte M.

    2010-05-01

    Within the context of the Heidelberg Basin Project (Gabriel et al. 2008), we present the first results of three-dimensional structural modelling of the basin, based on interpretation of reflection seismics and decompaction using porosity data measured from core material. Firstly, we interpreted six horizons (Base Quaternary, Internal and Base Pliocene, Base Upper Miocene, Internal and Base Mid Miocene Hydrobien beds) from all available industrial (ca. 100 km) and our own reflection seismic sections (ca. 15 km), which lie within a 8 km radius around the Heidelberg UniNord 1/2 boreholes. This data was used to construct a three-dimensional geometrical model of the Heidelberg Basin. Using 300 core samples, we determined the porosity of the Quaternary sediments and constructed an exponential porosity/depth relationship for these rocks, which were then attributed to the model. Lower strata were given values from the literature. The model shows that the Heidelberg basin has a N-S and E-W areal extent of only 10 × 6 km, directly abutting the eastern fault boundary of the Upper Rhine Graben. The strongest synsedimentary tectonic subsidence occurred during the Upper Miocene, Upper Pliocene, and Quarternary. Faults are not seen within the basin at this level, but a NW-SE striking strike-slip structure is recorded to the west of the basin. Furthermore, the sedimentary depocentre shifted 2 km northwards over time to the present location, directly below the city of Heidelberg. We determined that Quaternary sediments have porosities of over 60% at the surface, but at the Base Quaternary porosity is less than 35%. This strong decrease means that 740 m of sediments were compacted to produce the present ca. 500 m thickness of Quaternary strata. Gabriel, G., Ellwanger, D., Hoselmann, C. & Weidenfeller, M. (2008): The Heidelberg Basin Drilling Project. -- Quaternary Science Journal, 57, 3-4, 253-260.

  9. Suceava Anthropic Torrential Basin - Prolegomena

    Directory of Open Access Journals (Sweden)

    Andrei-Emil BRICIU

    2010-05-01

    Full Text Available One problem discussed by urban hydrology today is the draining influence of the modern cities over the natural drainage systems. The increasing urban areas and of their imperviousness all over theworld is linked to floods shape modifications and unpredicted systemic implications.  Generally, the draining influence of a city over its environment begins when it has a surface great enough to create an anthropic-generated runoff during a rain with enoughprecipitations to provoke waters accumulation into street torrents. The size, imperviousness, precipitations, drainage system and water consumption of the Suceava city are analysed in order to estimate the discharge of the city into Suceava river at various rainfalls. The article is structured as follows:1. Argumentation on the class separation between natural and anthropic torrential basins.2. Placing Suceava city as one of the torrential anthropic basins in Romania using basic arguments.3. Extending one of the argument, the importance of the rainfalls, in more detailed discussions (rainfall characteristics mainly, but also its cumulative effect with the floods on the Suceava river and the consumption of water in the city, with two scenarios. 4. The city is analysed as being integrated into a metropolitan area which can exacerbate the influence of the main city over the surrounding natural drainage basins nearby that area.5. Conclusions, where measures are proposed in order to diminish the potential negative effects on environment and human society.This article is only an introduction to a more detailed analysis which will be complete with further field data.

  10. Synchronous changes in the rift-margin San Jose Island basin and initiation of the Alarcón spreading ridge: implications for rift to drift transition in the Gulf of California

    Science.gov (United States)

    Umhoefer, P. J.; Sutherland, F.; Kent, G.; Harding, A.; Lizarralde, D.; Fletcher, J.; Holbrook, W.; Axen, G.; González-Fernández, A.

    2007-12-01

    The rift to drift hypothesis is widely cited, but it well known in detail. The low sedimentation rate and recent rifting of the Gulf of California provides insight into the rift-to-drift process. Lizarralde et al. (2007) showed that the style of rifting, based on crustal structure, varies significantly between the central and southern Gulf of California, and this combined with the analysis of sedimentary basins shows the small-scale (~15 km) complexities of the rift-to-drift transition. The shut off of rifting on the eastern side of the plate boundary occurred at ca. 2 - 3 Ma (Aragon-Arreola etal, 2005, Aragon-Arreola & Martin-Barajas, 2007; our unpublished data). Many studies have shown that the western side of the Gulf is still active despite sea-floor spreading occurring on the Alarcón and other short spreading centers since 2 - 3 Ma. At the mouth of the Gulf, magnetic anomalies on the eastern side of the Alarcón rise show that it appears to have changed to seafloor spreading as early as 3.7 Ma. But comparatively, on the eastern side, magnetic anomalies do not indicate the formation of new oceanic crust until 2.5 Ma, so spreading was first fully established at 2.5 Ma. The San Jose Island basin (Umhoefer et al., 2007) began at approximately 4- 6 Ma; the basin had its most rapid subsidence, with faulting accompanying marine sedimentation, from 3.6 ± 0.5 Ma (Ar tuff age) to 2.5-2.4 Ma (forams). Basin margin faulting died and moved east (offshore) shortly after 2.5-2.4 Ma. Late Quaternary marine terraces suggest that faulting rates slowed by 1-2 orders of magnitude since the fault reorganization at 2.5 Ma. These observations suggest that the rift - drift transition started, but is not yet finished, on the western side of the Gulf of California, with low rates of faulting (<1? mm/yr) continuing on the continental margin for reasons that are not well understood. Our work highlights the importance of combining onshore field and MSC data and analyzing entire conjugate rifted margins to accurately assess rifting processes.

  11. Sr, Nd, and Pb isotope compositions of hemipelagic sediment in the Shikoku Basin: Implications for sediment transport by the Kuroshio and Philippine Sea plate motion in the late Cenozoic

    Science.gov (United States)

    Saitoh, Yu; Ishikawa, Tsuyoshi; Tanimizu, Masaharu; Murayama, Masafumi; Ujiie, Yurika; Yamamoto, Yuzuru; Ujiie, Kohtaro; Kanamatsu, Toshiya

    2015-07-01

    The provenance of hemipelagic sediments in the Shikoku Basin during late Cenozoic time was studied through the temporal variations in the Sr-Nd-Pb isotopic compositions of detrital sediments from Integrated Ocean Drilling Program Site C0011 from the late Miocene (7 Ma) to the present. Detrital sediments at Site C0011 are interpreted as a mixture of sediments originating from the southwest Japan arc and lands around the East China Sea. Sediments from the East China Sea were transported by the Kuroshio, while Japanese sediments were transported by turbidity currents, bottom currents, and ocean surface currents. The isotopic evidence suggests that the main source of hemipelagic sediments gradually changed from the East China Sea to Japan from 4.4 to 2.9 Ma, in accordance with the northward movement of Site C0011 with the Philippine Sea plate in this period. A contemporaneous increase in grain size also supports this interpretation. The beginning period of these changes, 4.4 Ma, conforms closely to the postulated advent or acceleration of trench-normal subduction of the Shikoku Basin lithosphere.

  12. Uranium isotopes (234U/238U) in rivers of the Yukon Basin (Alaska and Canada) as an aid in identifying water sources, with implications for monitoring hydrologic change in arctic regions

    Science.gov (United States)

    Kraemer, Thomas F.; Brabets, Timothy P.

    2012-05-01

    The ability to detect hydrologic variation in large arctic river systems is of major importance in understanding and predicting effects of climate change in high-latitude environments. Monitoring uranium isotopes (234U and 238U) in river water of the Yukon River Basin of Alaska and northwestern Canada (2001-2005) has enhanced the ability to identify water sources to rivers, as well as detect flow changes that have occurred over the 5-year study. Uranium isotopic data for the Yukon River and major tributaries (the Porcupine and Tanana rivers) identify several sources that contribute to river flow, including: deep groundwater, seasonally frozen river-valley alluvium groundwater, and high-elevation glacial melt water. The main-stem Yukon River exhibits patterns of uranium isotopic variation at several locations that reflect input from ice melt and shallow groundwater in the spring, as well as a multi-year pattern of increased variability in timing and relative amount of water supplied from higher elevations within the basin. Results of this study demonstrate both the utility of uranium isotopes in revealing sources of water in large river systems and of incorporating uranium isotope analysis in long-term monitoring of arctic river systems that attempt to assess the effects of climate change.

  13. Melo carboniferous basin

    International Nuclear Information System (INIS)

    This report is about of the Melo carboniferous basin which limits are: in the South the large and high Tupambae hill, in the west the Paraiso hill and the river mountains, in the North Yaguaron river basin to Candidata in Rio Grande del Sur in Brazil.

  14. K Basin safety analysis

    International Nuclear Information System (INIS)

    The purpose of this accident safety analysis is to document in detail, analyses whose results were reported in summary form in the K Basins Safety Analysis Report WHC-SD-SNF-SAR-001. The safety analysis addressed the potential for release of radioactive and non-radioactive hazardous material located in the K Basins and their supporting facilities. The safety analysis covers the hazards associated with normal K Basin fuel storage and handling operations, fuel encapsulation, sludge encapsulation, and canister clean-up and disposal. After a review of the Criticality Safety Evaluation of the K Basin activities, the following postulated events were evaluated: Crane failure and casks dropped into loadout pit; Design basis earthquake; Hypothetical loss of basin water accident analysis; Combustion of uranium fuel following dryout; Crane failure and cask dropped onto floor of transfer area; Spent ion exchange shipment for burial; Hydrogen deflagration in ion exchange modules and filters; Release of Chlorine; Power availability and reliability; and Ashfall

  15. The Rhodope Zone as a primary sediment source of the southern Thrace basin (NE Greece and NW Turkey): evidence from detrital heavy minerals and implications for central-eastern Mediterranean palaeogeography

    Science.gov (United States)

    Caracciolo, L.; Critelli, S.; Cavazza, W.; Meinhold, G.; von Eynatten, H.; Manetti, P.

    2015-04-01

    Detrital heavy mineral analysis coupled with a regional geological review provide key elements to re-evaluate the distribution of the Rhodope metamorphic zone (SE Europe) in the region and its role in determining the evolution of the Thrace basin. We focus on the Eocene-Oligocene sedimentary successions exposed in the southern Thrace basin margin to determine the dispersal pathways of eroded crustal elements, of both oceanic and continental origins, as well as their different contributions through time. Lithological aspects and tectonic data coupled with geochemistry and geochronology of metamorphic terranes exposed in the area point to a common origin of tectonic units exposed in NW Turkey (Biga Peninsula) with those of NE Greece and SE Bulgaria (Rhodope region). The entire region displays (1) common extensional signatures, consisting of comparable granitoid intrusion ages, and a NE-SW sense of shear (2) matching zircon age populations between the metapelitic and metamafic rocks of the Circum-Rhodope Belt (NE Greece) and those of the Çamlica-Kemer complex and Çetmi mélange exposed in NW Turkey. Detrital heavy mineral abundances from Eocene-Oligocene sandstones of the southern Thrace basin demonstrate the influence of two main sediment sources mostly of ultramafic/ophiolitic and low- to medium-grade metamorphic lithologies, plus a third, volcanic source limited to the late Eocene-Oligocene. Detrital Cr-spinel chemistry is used to understand the origin of the ultramafic material and to discriminate the numerous ultramafic sources exposed in the region. Compositional and stratigraphic data indicate a major influence of the metapelitic source in the eastern part (Gallipoli Peninsula) during the initial stages of sedimentation with increasing contributions from metamafic sources through time. On the other hand, the western and more external part of the southern Thrace margin (Gökçeada, Samothraki and Limnos) displays compositional signatures according to a mixed provenance from the metapelitic and metamafic sources of the Circum-Rhodope Belt (Çaml?ca-Kemer complex and Çetmi mélange). Tectonic restoration and compositional signatures provide constraints on the Palaeogene palaeogeography of this sector of the central-eastern Mediterranean region.

  16. Depositional environments and characterisation of the organic matter of the Lower Mundeck Formation (Barremian ? Aptian) of the Kribi-Campo sub-basin (South Cameroon): Implications for petroleum exploration

    Science.gov (United States)

    Ntamak-Nida, Marie-Joseph; Baudin, François; Schnyder, Johann; Makong, Jean-Claude; Komguem, Paul Bertrand; Abolo, Guy Martin

    2008-07-01

    Lacustrine and alluvial fan facies from the Lower Mundeck Formation (Barremian ?-Aptian) cropping out in the southern part of the Kribi-Campo sub-basin (Cameroon) have been characterised for their oil potential, using both Rock-Eval pyrolysis and palynofacies analyses. The shaly facies show good potential as oil-prone source rock, with TOC content around 4.4% and some intervals with an optimum potential to yield 45 kg hydrocarbons/t of rock. Along the studied outcrops, these organic-rich facies represent approximately a third of the total thickness. Although the studied samples come out from immature thin organic-rich beds within sand dominated beds, it is reasonable to think that these oil-prone facies increase in thickness and maturity in the offshore area, making this part of the southern margin of Cameroon of special interest for petroleum exploration.

  17. U-Pb and Pb-Pb study of the Murchison Greenstone Belt and of the Evander gold-bearing basin, South Africa. Implications for the evolution of the Kaapvaal craton

    International Nuclear Information System (INIS)

    This study presents new U-Pb and Pb-Pb isotopic data for both the Central Rand Group from the Evander Goldfield and the Murchison Greenstone Belt (Republic of South Africa). The Evander Goldfield, where no previous isotopic data have been derived, is located in the eastern side of the Witwatersrand basin. The oldest age measured is ca. 3180 Ma, while the majority of detritus falls in the range 3050-2850 Ma. New growth of zircon (or isotopic resetting of older detritus) appears to have been associated with deposition of the Ventersdorp lavas at ca. 2.7 Ga. A small proportion of the pyrite, mainly extracted from unaltered sediments in the Kimberley Reef footwall, yields ages that are in excess of the minimum depositional age of the Witwatersrand Basin. Authigenic pyrite, as well as detrital grains from highly altered portions of the Kimberley Reef, define two main events. The Pb signature of the 2370 Ma event is probably associated with burial of the basin by the upper portion of the Transvaal sequence, and suggests circulation of highly radiogenic fluids. Isotopic signatures for the 2020 Ma event are probably related to Bushveld intrusion and/or Vredefort catastrophism, and appear to be associate with a fluid that was less radiogenic. The present study shows a number of new results which support a complex, multi-stage evolution and genesis of the Au-U deposits within the Witwatersrand Basin. The Murchison Greenstone Belt constitutes one of the world's largest antimony producing areas and also hosts gold, as well as volcanogenic massive sulfide Cu-Zn mineralization and emeralds. The goal of this study is to determine the age of the belt as well as the timing of mineralization and, also, to assess the potential role of granitoids in the ore-forming processes. The data identify an episode of greenstone formation between 3.09 Ga and 2.97 Ga. Three main magmatic events are identified at ca. 2.97, 2.82 and 2.68 Ga. Pyrites associated with both Sb-Au and Cu-Zn mineralization define a secondary isochron with an age of 2.97 Ga suggesting that they are spatially and genetically associated with the 2.97 Ga Maranda Batholith and the volcanic Rubbervale Formation. Thus, VMS style Cu-Zn mineralization is syn-genetic with respect to the Rubbervale Formation, whereas Sb-Au lode mineralization along the Antimony Line appears to be related to magmatic fluid egress from the Maranda batholith. Pb-Pb signatures of pyrite associated with emerald along the southern flank of the reflect mixing between Pb derived from the older 3.23 Ga basement and the 2.97 Ga magmatic event. The 2.97 Ga Maranda batholith and Rubbervale Formation, therefore, represents a highly prospective metallotect that is relevant, not only to exploration in the Murchison region itself, but to the important question of the source of Witwatersrand gold. (authors)

  18. UPPER SNAKE RIVER BASIN, PRELIMINARY BASIN EVALUATION

    Science.gov (United States)

    The purpose of this paper was to provide a process and a plan by which the Environmental Protection Agency can insure that water quality goals established in the Water Pollution Control Act Amendments of 1972 are met in the waters of the Upper Snake Basin (17040201, 17040206, 170...

  19. Reserves in western basins

    Energy Technology Data Exchange (ETDEWEB)

    Caldwell, R.H.; Cotton, B.W. [Scotia Group, Dallas, TX (United States)

    1995-04-01

    The objective of this project is to investigate the reserves potential of tight gas reservoirs in three Rocky Mountain basins: the Greater Green River (GGRB), Uinta and Piceance basins. The basins contain vast gas resources that have been estimated in the thousands of Tcf hosted in low permeability clastic reservoirs. This study documents the productive characteristics of these tight reservoirs, requantifies gas in place resources, and characterizes the reserves potential of each basin. The purpose of this work is to promote understanding of the resource and to encourage its exploitation by private industry. At this point in time, the GGRB work has been completed and a final report published. Work is well underway in the Uinta and Piceance basins which are being handled concurrently, with reports on these basins being scheduled for the middle of this year. Since the GGRB portion of the project has been completed, this presentation win focus upon that basin. A key conclusion of this study was the subdivision of the resource, based upon economic and technological considerations, into groupings that have distinct properties with regard to potential for future producibility, economics and risk profile.

  20. Constraints on Moho Depth and Crustal Thickness in the Liguro-Provençal Basin from a 3d Gravity Inversion : Geodynamic Implications Contraintes sur la profondeur du moho et l'épaisseur crustale dans le bassin liguro-provençal à partir de l'inversion 3D de données gravimétriques : implications géodynamiques

    Directory of Open Access Journals (Sweden)

    Gaulier J. M.

    2006-12-01

    Full Text Available 3D gravity modelling is combined with seismic refraction and reflection data to constrain a new Moho depth map in the Liguro-Provençal Basin (Western Mediterranean Sea. At seismically controlled points, the misfit between the gravimetric solution and the seismic data is about 2 km for a range of Moho depth between 12 km (deep basin and 30 km (mainlands. The oceanic crust thickness in the deep basin (5 km is smaller than the average oceanic crust thickness reported in open oceans (7 km, pointing to a potential mantle temperature 30°C to 50°C below normal and/or very slow oceanic spreading rate. Oceanic crust thickness is decreasing towards the Ligurian Sea and towards the continent-ocean boundary to values as small as 2 km. Poor magma supply is a result of low potential mantle temperature at depth, lateral thermal conduction towards unextended continental margin, and decrease of the oceanic spreading rate close to the pole of opening in the Ligurian Sea. Re-examination of magnetic data (paleomagnetic data and magnetic lineations indicates that opening of the Liguro-Provençal Basin may have ceased as late as Late Burdigalian (16. 5 Ma or even later. The absence of significant time gap between cessation of opening in the Liguro-Provençal Basin and rifting of the Tyrrhenian domain favours a continuous extension mechanism since Upper Oligocene driven by the African trench retreat. Ce rapport présente un travail commun avec le Laboratoire de géodynamique de l'École normale supérieure (ENS. Ce travail doit être resitué dans son contexte : l'étude régionale du golfe du Lion a été possible dans le cadre du projet européen Integrated Basin Studies. Le développement du code d'inversion 3D avait fait l'objet de conventions avec l'ENS pendant les années précédentes. La mise en Suvre d'une telle inversion est désormais possible à l'IFP. Il n'y a pas d'interface pour ce calculateur. L'aide des collègues de l'ENS est souhaitable pour la mise en forme des données. Il a paru opportun, compte tenu des délais imprévus de publication du volume du BSGL pour lequel cet article a été accepté, de montrer l'existence et les potentialités de cette méthode. Il est vraisemblable qu'elle pourra être un apport significatif à l'étude des marges passives et plus particulièrement dans le cas des études concernant l'offshore profond. Elle a déjà retenu l'attention de plusieurs collègues de l'industrie pétrolière.

  1. L'évolution paléoenvironnementale des faunes de poissons du Crétacé supérieur du bassin du Tafilalt et des régions avoisinantes (Sud-Est du Maroc) : implications paléobiogéographiquesPalaeoenvironmental evolution of the fish assemblages from the Late Cretaceous of the Tafilalt basin and surrounding areas, southeastern Morocco: palaeogeographical implications

    Science.gov (United States)

    Cavin, Lionel; Boudad, Larbi; Duffaud, Sylvain; Kabiri, Lahcen; Le Lœuff, Jean; Rouget, Isabelle; Tong, Haiyan

    2001-11-01

    A critical revision of published data along with new field data allow to draw up the succession of the fish faunas from the Lower Cenomanian to the Lower Turonian in the Tafilalt basin and surrounding areas (southeast Morocco). The analysis of these faunas shows changes from freshwater to marine palaeoenvironments. The palaeogeographic distribution of some taxa is discussed. It shows that the crossing of strictly freshwater organisms between Africa and South America was likely impossible at the time of the formation of the deposits resting around the Tafilalt basin and named 'Kem Kem beds'. The Cenomano-Turonian transgression reached the Erfoud-Errachidia carbonate platform from the Central Tethys, and then connected the central Atlantic.

  2. Geochemistry and characteristics of nitrogen transport at a confined animal feeding operation in a coastal plain agricultural watershed, and implications for nutrient loading in the Neuse River basin, North Carolina, 1999-2002

    Science.gov (United States)

    Spruill, T.B.; Tesoriero, A.J.; Mew, H.E., Jr.; Farrell, K.M.; Harden, S.L.; Colosimo, A.B.; Kraemer, S.R.

    2005-01-01

    Chemical, geologic, hydrologic, and age-dating information collected between 1999 and 2002 were used to examine the transport of contaminants, primarily nitrogen, in ground water and the pathways to surface water in a coastal plain setting in North Carolina. Data were collected from more than 35 wells and 4 surface-water sampling sites located in a 0.59 square-mile basin to examine detailed hydrogeology and geochemical processes affecting nutrient fate and transport. Two additional surface-water sampling sites were located downstream from the primary study site to evaluate basin-scale effects. Chemical and flow data also were collected at an additional 10 sites in the Coastal Plain portion of the Neuse River basin located between Kinston and New Bern, North Carolina, to evaluate loads transported in the Neuse River and primary tributary basins. At the Lizzie Research Station study site in North Carolina, horizontal flow is induced by the presence of a confining unit at shallow depth. Age-dating, chemical, and piezometric data indicate that horizontal flow from the surficial aquifer is the dominant source of ground water to streamflow. Nitrogen applied on cultivated fields at the Lizzie Research Station is substantially reduced as it moves from recharge to discharge areas. Denitrification in deeper parts of the aquifer and in riparian zones is indicated by a characterization of redox conditions in the aquifer and by the presence of excess nitrogen gas. Direct ground-water discharge of nitrate to surface water during base-flow conditions is unlikely to be significant because of strongly reducing conditions that occur in the riparian zones of these streams. Nitrate loads from a drainage tile at the study site may account for much of the nitrate load in the receiving stream, indicating that a major source of nutrients from ground water to this stream is artificial drainage. During base-flow conditions when the streams are not flowing, it is hypothesized that the mineralization of organic matter on the streambed is the source of nitrate and(or) ammonium in the stream. Base flow is a small contributor to nitrogen loads, because both flows and inorganic nitrogen concentrations are low during summer months. Effects of a confined hog operation on ground-water quality also were evaluated. The use of sprayed swine wastes to fertilize crops at the Lizzie Research Station study site since 1995 resulted in increased concentrations of nitrate and other chemical constituents in ground water beneath spray fields when compared to ground water beneath fields treated with commercial fertilizer. The nitrate concentration in ground water from the spray field well increased by a factor of 3.5 after 4 years of spray applications. Nitrate concentrations ranged from 10 to 35 milligrams per liter, and one concentration as high as 56 milligrams per liter was observed in water from this well in spring 2002. This finding is in agreement with findings of other studies conducted in the Coastal Plain of North Carolina that nitrate concentrations were significantly higher in ground water from cultivated fields sprayed with swine wastes than from fields treated with commercial fertilizer. Loads and yields of nitrogen and phosphorus in 14 streams in the Neuse River basin were evaluated for calendar years 2000 and 2001. Data indicate that anthropogenic effects on nitrogen yields were greatest in the first-order stream studied (yields were greater than 2 tons per square mile [ton/mi2] and 1 ton/mi2 or less in second- and higher-order streams) in the Little Contentnea Creek subbasin. Nitrogen yields in streams in the Contentnea Creek subbasin ranged from 0.59 to 2 ton/mi2 with typical yields of approximately 1 ton/mi2. Contentnea Creek near Evansdale had the highest yield (2 ton/mi2), indicating that a major source of nitrogen is upstream from this station. Nitrogen yields were lower at Contentnea Creek at Hookerton in 2000 and 2001 compared to previous yi

  3. THERMAL MATURITY HISTORY AND IMPLICATIONS FOR HYDROCARBON EXPLORATION IN THE CATATUMBO BASIN, COLOMBIA Historia de la madurez térmica e implicaciones para la exploración de hidrocarburos en la cuenca del Catatumbo, Colombia

    Directory of Open Access Journals (Sweden)

    Antonio Rangel

    2007-12-01

    Full Text Available A thermal model integrated with an oil and gas geochemical study has been constructed for the Catatumbo Basin, Colombia to provide petroleum system data for hydrocarbon exploration. The calibration of the thermal model with maturity data took into account a changing heat flow scheme which included a thermal increase towards the end of the Jurassic and another one in the Early Eocene, associated with rifting events. Locally, active/generating source rocks are within the synclines axes. The hydrocarbon expulsion time for Cretaceous source rocks (Capacho and La Luna formations started in the Upper Paleocene-Eocene, while for the Los Cuervos Formation the generation and expulsion started at 10 my. The petroleum expelled during the Paleocene-Miocene, were likely accumulated in structures formed since the end of the Cretaceous, while the younger structures that resulted from the Andean orogen were charged by remigration from the older structures and additionally with the yougest lately generated hydrocarbons. The accumulations of hydrocarbons are mainly the result of generation and migration locally within the basin. The Catatumbo basin contains thermogenic wet gases with different degrees of thermal maturity which varies from around 1,0 to 2,5 equivalent Ro. The highest degree of thermal evolution according to maturity indicators and thermal modeling is in the southern area, which is prospective for wet gas. The central and northern area appears more prospective for oil with minor amounts of gas.Un modelamiento integrado con un estudio geoquímico de gas y aceite ha sido realizado en la cuenca del Catatumbo, Colombia con el fin de proveer información para la exploración de hidrocarburos. El ajuste del modelo térmico con los datos de madurez fue posible a partir de un esquema de flujo de calor cambiante, que incluyó un incremento térmico hacia finales del Jurásico y otro en el Eoceno Temprano, asociados a eventos distensivos. Regionalmente, en los ejes de los sinclinales se identificaron pods de roca fuente activa en el presente. Los tiempos de expulsión de hidrocarburos para las rocas fuente Cretáceas (Formación Capacho y la Luna, inician en el Paleoceno-Eoceno Superior mientras que para la Formación Los Cuervos la generación y expulsión inicia hace 10 ma. Las acumulaciones de hidrocarburos se infiere que son el resultado principalmente de generación y migración dentro de la cuenca. La fracción de petróleo expulsado durante el Paleoceno-Mioceno posiblemente fue acumulada en estructuras que crecieron desde finales del Cretácico, mientras que las estructuras más jovenes resultantes de la orogenia andina se infiere que se han cargado con los productos de la remigración desde las estructuras más antiguas y adicionalmente con las últimas fracciones de hidrocarburos generadas. Los gases de la cuenca Catatumbo son del tipo termogénico húmedos con diferente grado de madurez termal que varía desde alrededor de 1,0 hasta 2,5 de Ro equivalente. De acuerdo con el grado de evolución termal, la geoquímica y el modelamiento térmico, se infiere que la región sur es prospectiva para gas húmedo y condensado, mientras que el sector central y norte es prospectivo para aceite y cantidades menores de gas asociado.

  4. THERMAL MATURITY HISTORY AND IMPLICATIONS FOR HYDROCARBON EXPLORATION IN THE CATATUMBO BASIN, COLOMBIA / Historia de la madurez térmica e implicaciones para la exploración de hidrocarburos en la cuenca del Catatumbo, Colombia

    Scientific Electronic Library Online (English)

    Antonio, Rangel; Roberto, Hernández.

    2007-12-01

    Full Text Available Un modelamiento integrado con un estudio geoquímico de gas y aceite ha sido realizado en la cuenca del Catatumbo, Colombia con el fin de proveer información para la exploración de hidrocarburos. El ajuste del modelo térmico con los datos de madurez fue posible a partir de un esquema de flujo de calo [...] r cambiante, que incluyó un incremento térmico hacia finales del Jurásico y otro en el Eoceno Temprano, asociados a eventos distensivos. Regionalmente, en los ejes de los sinclinales se identificaron pods de roca fuente activa en el presente. Los tiempos de expulsión de hidrocarburos para las rocas fuente Cretáceas (Formación Capacho y la Luna), inician en el Paleoceno-Eoceno Superior mientras que para la Formación Los Cuervos la generación y expulsión inicia hace 10 ma. Las acumulaciones de hidrocarburos se infiere que son el resultado principalmente de generación y migración dentro de la cuenca. La fracción de petróleo expulsado durante el Paleoceno-Mioceno posiblemente fue acumulada en estructuras que crecieron desde finales del Cretácico, mientras que las estructuras más jovenes resultantes de la orogenia andina se infiere que se han cargado con los productos de la remigración desde las estructuras más antiguas y adicionalmente con las últimas fracciones de hidrocarburos generadas. Los gases de la cuenca Catatumbo son del tipo termogénico húmedos con diferente grado de madurez termal que varía desde alrededor de 1,0 hasta 2,5 de Ro equivalente. De acuerdo con el grado de evolución termal, la geoquímica y el modelamiento térmico, se infiere que la región sur es prospectiva para gas húmedo y condensado, mientras que el sector central y norte es prospectivo para aceite y cantidades menores de gas asociado. Abstract in english A thermal model integrated with an oil and gas geochemical study has been constructed for the Catatumbo Basin, Colombia to provide petroleum system data for hydrocarbon exploration. The calibration of the thermal model with maturity data took into account a changing heat flow scheme which included a [...] thermal increase towards the end of the Jurassic and another one in the Early Eocene, associated with rifting events. Locally, active/generating source rocks are within the synclines axes. The hydrocarbon expulsion time for Cretaceous source rocks (Capacho and La Luna formations) started in the Upper Paleocene-Eocene, while for the Los Cuervos Formation the generation and expulsion started at 10 my. The petroleum expelled during the Paleocene-Miocene, were likely accumulated in structures formed since the end of the Cretaceous, while the younger structures that resulted from the Andean orogen were charged by remigration from the older structures and additionally with the yougest lately generated hydrocarbons. The accumulations of hydrocarbons are mainly the result of generation and migration locally within the basin. The Catatumbo basin contains thermogenic wet gases with different degrees of thermal maturity which varies from around 1,0 to 2,5 equivalent Ro. The highest degree of thermal evolution according to maturity indicators and thermal modeling is in the southern area, which is prospective for wet gas. The central and northern area appears more prospective for oil with minor amounts of gas.

  5. La pesca artesanal en la Cuenca del Plata (Argentina) y sus implicancias en la conservación de la biodiversidad / Artisanal fish at del Plata basin (Argentina) and its implications for the biodiversity conservation

    Scientific Electronic Library Online (English)

    Juan Miguel, Iwaszkiw; Francisco, Firpo Lacoste.

    2011-06-01

    Full Text Available El objetivo del presente trabajo es considerar distintos aspectos que surgen del análisis de las exportaciones pesqueras provenientes de la pesca comercial artesanal de la Cuenca del Plata, Argentina. Se trata de identificar aquellos impactos vinculados a las prácticas pesqueras sobre las poblacione [...] s naturales involucradas y los compromisos relacionados con la conservación de la biodiversidad de la ictiofauna de la cuenca. Se analizan 17 años de datos de las pesquerías comerciales artesanales correspondientes al tramo argentino del río Paraná sobre registros oficiales de los productos pesqueros exportados para distintas especies durante el período 1994-2010. Los registros de los productos exportados expresados en toneladas en peso (ton) se refieren particularmente a especies autóctonas de gran tamaño e interés comercial como el sábalo (Prochilodus lineatus), la boga (Leporinus obtusidens), la tararira (Hoplias malabaricus), el surubí (Pseudoplatystoma spp.), el dorado (Salminus brasiliensis) y el patí (Luciopimelodus pati), además de varias especies acompañantes en las capturas como bagres, armados y pejerreyes (Odontesthes bonariensis). Las exportaciones pesqueras muestran un incremento sumamente importante con un total de 331.517 ton para el período 1994-2010. La especie blanco de la pesquería es el sábalo con 88,77 % de las exportaciones totales y le siguen en orden de importancia la tararira con el 4,16 %, la boga con el 3,70 %, el patí con un 1,35 % y otras especies de menor captura. Los países de destino de los productos pesqueros son Brasil, Colombia, Bolivia y Nigeria, entre otros. Sin embargo, desde el 2003, Colombia compra en promedio el 50 % del total de las exportaciones pesqueras de la Argentina. El análisis de los datos históricos de las exportaciones pesqueras (1994-2010) evidencia la necesidad de implementar medidas mas claras sobre el control y manejo de los recursos pesqueros y las posibles implicancias derivadas de la pesquería sobre conservación de la biodiversidad de peces de la cuenca. Abstract in english The aim of this contribution is to consider different issues derived from fish captures from artisanal-commercial fisheries in the Paraná Basin in Argentina. We identify certain impacts related to fishing practices on the involved natural populations and its compromises in ichtiofaunal biodiversity [...] conservation. We consider 17 years of information based on data of fisheries exports for different inland species between 1994-2010. These data includes valuable commercial big sized native fishes like sábalo (Prochilodus lineatus), boga (Leporinus obtusidens), tararira (Hoplias malabaricus), surubí (Pseudoplatystoma spp.), dorado (Salminus brasiliensis) and patí (Luciopimelodus pati), together with several catfish species and minor species as silversides. Freshwater fish exports show a major rise resulting in 331517 ton for these years. The target species is sábalo (88.77 %), other accompanying species are tararira (4.16 %), boga (3.7 %) and Patí (1.35 %) whereas the remainig catches belong to other species. There is a strong rise in the catches of these other species in certain years while there is not a clear legislation for these fish species that allow implementing a proper fishery management along the basin. The importing countries are Brazil, Colombia, Bolivia and Nigeria among others. Since 2003 Colombia buy an average of 50% of inland fisheries exports from Argentina. The analysis historical data (1994-2010) reveals the need to implement measures to control and management of fisheries and its effects on fish biodiversity conservation in the basin.

  6. California Air Basins

    Data.gov (United States)

    California Department of Resources — Air ResourcesCalifornia Air Resources BoardThe following datasets are from the California Air Resources Board: * arb_california_airbasins - California Air BasinsThe...

  7. Early Mesozoic basin aquifers

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set represents the extent of the Early Mesozoic basin aquifers in the states of Massachusettes, Connecticut, New York, New Jersey, Pennsylvania, Maryland,...

  8. Palaeohydrology of the Fazzan Basin, Libyan Sahara

    Science.gov (United States)

    Armitage, Simon

    2010-05-01

    The Fazzan is a large closed basin with an area of 450,000 km2, located in south-western Libya. The present-day climate is hyper-arid, with less than 20 mm of rainfall per annum. However, regionally extensive limestones, lacustrine sands, coquina (fossiliferous carbonate rock) and fine grained lake deposits demonstrate that the Fazzan Basin previously contained a large palaeolake, here termed Lake Mega-Fazzan. Although the Sahara contains evidence of several other large palaeolakes, of which Lake Mega-Chad is best known and largest, Lake Mega-Fazzan is the only one fed exclusively by rivers draining the Sahara proper. Thus, the Lake Mega-Fazzan sediments provide an important resource for advancing our understanding of climate change in this part of the Sahara. However, systematic examination of this palaeoclimate record has, to some extent, been hindered by the relative paucity of dateable material from within these deposits. Optically stimulated luminescence (OSL) dating techniques have been applied to a range of lacustrine deposits within the basin to provide an internally consistent chronology for the Fazzan humidity record. Results indicate that sediments within the Fazzan Basin record a very long history of palaeohydrological change. The oldest lacustrine sediments are beyond the range of conventional OSL dating techniques, but younger humid periods during oxygen isotope stages 11, 5 and 1 are recognised. These results, when compared with similar studies of adjacent closed basins, indicate that the Sahara may not always have provided as formidable a barrier to faunal migration as it does at present. The implications of this finding for our understanding of African biogeography and palaeoanthropology will be discussed.

  9. Magmatism in rifting and basin formation

    Science.gov (United States)

    Thybo, H.

    2008-12-01

    Whether heating and magmatism cause rifting or rifting processes cause magmatic activity is highly debated. The stretching factor in rift zones can be estimated as the relation between the initial and the final crustal thickness provided that the magmatic addition to the crust is insignificant. Recent research demonstrates substantial magmatic intrusion into the crust in the form of sill like structures in the lowest crust in the presently active Kenya and Baikal rift zones and the DonBas palaeo-rift zone in Ukraine. This result may be surprising as the Kenya Rift is associated with large amounts of volcanic products, whereas the Baikal Rift shows very little volcanism. Identification of large amounts of magmatic intrusion into the crust has strong implications for estimation of stretching factor, which in the case of Baikal Rift Zone is around 1.7 but direct estimation gives a value of 1.3-1.4 if the magmatic addition is not taken into account. This may indicate that much more stretching has taken place on rift systems than hitherto believed. Wide sedimentary basins may form around aborted rifts due to loading of the lithosphere by sedimentary and volcanic in-fill of the rift. This type of subsidence will create wide basins without faulting. The Norwegian- Danish basin in the North Sea area also has subsided gradually during the Triassic without faulting, but only few rift structures have been identified below the Triassic sequences. We have identified several mafic intrusions in the form of large batholiths, typically more than 100 km long, 20-40 km wide and 20 km thick. The associated heating would have lifted the surface by about 2 km, which may have been eroded before cooling. The subsequent contraction due to solidification and cooling would create subsidence in a geometry similar to basins that developed by loading. These new aspects of magmatism will be discussed with regard to rifting and basin formation.

  10. K Basins Hazard Analysis

    International Nuclear Information System (INIS)

    This report describes the methodology used in conducting the K Basins Hazard Analysis, which provides the foundation for the K Basins Safety Analysis Report (HNF-SD-WM-SAR-062/Rev.4). This hazard analysis was performed in accordance with guidance provided by DOE-STD-3009-94, Preparation Guide for U. S. Department of Energy Nonreactor Nuclear Facility Safety Analysis Reports and implements the requirements of DOE Order 5480.23, Nuclear Safety Analysis Report

  11. K Basin Hazard Analysis

    International Nuclear Information System (INIS)

    This report describes the methodology used in conducting the K Basins Hazard Analysis, which provides the foundation for the K Basins Final Safety Analysis Report. This hazard analysis was performed in accordance with guidance provided by DOE-STD-3009-94, Preparation Guide for U. S. Department of Energy Nonreactor Nuclear Facility Safety Analysis Reports and implements the requirements of DOE Order 5480.23, Nuclear Safety Analysis Report

  12. K Basin Hazard Analysis

    Energy Technology Data Exchange (ETDEWEB)

    PECH, S.H.

    2000-08-23

    This report describes the methodology used in conducting the K Basins Hazard Analysis, which provides the foundation for the K Basins Final Safety Analysis Report. This hazard analysis was performed in accordance with guidance provided by DOE-STD-3009-94, Preparation Guide for U. S. Department of Energy Nonreactor Nuclear Facility Safety Analysis Reports and implements the requirements of DOE Order 5480.23, Nuclear Safety Analysis Report.

  13. Origin and lateral migration of linear dunes in the Qaidam Basin of NW China revealed by dune sediments, internal structures, and optically stimulated luminescence ages, with implications for linear dunes on Titan: discussion

    Science.gov (United States)

    Rubin, David M.; Rubin, Alan M.

    2013-01-01

    Zhou et al. (2012) proposed that longitudinal dunes in the Qaidam Basin, China, formed like yardangs: by erosion into sediment that was not deposited by those dunes. Because erosion occurs on the upwind flanks of most migrating dunes (Rubin and Hunter, 1982, 1985), the key to demonstrating a yardang-like origin is to show that the dunes did not deposit the strata that they contain. Zhou et al. made this argument by proposing that: (1) The dunes have not deposited cross-strata in the past 810 yr. (2) Cross-bedding within the dunes was not deposited by the dunes on the present-day land surface, but rather by older dunes that had a different morphology. (3) The present dunes are a later generation, “most likely of erosional origin similar to yardangs with orientations controlled by strikes of joints,” (p. 1147). (4) Rates of deflation in the dune field have been extremely high for the past 810–2440 yr. This commentary reviews these conclusions, reviews contradictory observations, and considers alternative interpretations.

  14. A comparison of estimates of basin-scale soil-moisture evapotranspiration and estimates of riparian groundwater evapotranspiration with implications for water budgets in the Verde Valley, Central Arizona, USA

    Science.gov (United States)

    Tillman, Fred; Wiele, Stephen M.; Pool, Donald R.

    2015-01-01

    Population growth in the Verde Valley in Arizona has led to efforts to better understand water availability in the watershed. Evapotranspiration (ET) is a substantial component of the water budget and a critical factor in estimating groundwater recharge in the area. In this study, four estimates of ET are compared and discussed with applications to the Verde Valley. Higher potential ET (PET) rates from the soil-water balance (SWB) recharge model resulted in an average annual ET volume about 17% greater than for ET from the basin characteristics (BCM) recharge model. Annual BCM PET volume, however, was greater by about a factor of 2 or more than SWB actual ET (AET) estimates, which are used in the SWB model to estimate groundwater recharge. ET also was estimated using a method that combines MODIS-EVI remote sensing data and geospatial information and by the MODFLOW-EVT ET package as part of a regional groundwater-flow model that includes the study area. Annual ET volumes were about same for upper-bound MODIS-EVI ET for perennial streams as for the MODFLOW ET estimates, with the small differences between the two methods having minimal impact on annual or longer groundwater budgets for the study area.

  15. Stream Complexity in an Undisturbed Watershed of the Amazon Basin

    Science.gov (United States)

    Muttiah, R. S.; Khanal, S.; Janovec, J. P.

    2005-12-01

    The Madre De Dios watershed (drainage area 42,530 km2) which is in the headwater region of the Amazon basin is located in southeastern Peru. The watershed is in nearly pristine conditions with minimal human disturbance. The study area affords a rich research environment in which natural hydrologic processes under heavy rainfall can be studied. The streams in the basin were Strahler ordered, and complexity of catchments (sub-watersheds) were characterized. Implication of catchment complexity on delineating physiographic features will also be presented.

  16. Geochronological (Rb-Sr and Sm-Nd) studies on intrusive gabbro and dolerite dykes from parts of Northern and Central Indian cratons: implications for the age of onset of sedimentation in Bijawar and Chattisgarh basins and uranium mineralisation

    International Nuclear Information System (INIS)

    The Dargawan gabbros intrusive into the Moli Subgroup of Bijawar Group, yielded Rb-Sr whole rock isochron age of 1967 ± 140 Ma. Based on the oldest age from overlying Lower Vindhyan (1.6 Ga) and the underlying youngest basement ages (2.2 Ga), the time range of Bijawar sedimentation may be assigned as 2.1-1.6 Ga (Paleoproterozoic). Sm-Nd Model ages (TDM), obtained, for Dargawan gabbros, is c. 2876-3145 Ma. High initial 87Sr/86Sr ratio of 0.70451 (higher than the contemporary mantle) and negative ?Ndi (at 1.9 Ga) value of -1.5 to - 4.5, indicate assimilation of Archaean lower crustal component by the enriched mantle source magma at the time of gabbroic intrusion. The dolerite, from Damdama area, which is intrusive into the basement and overlying sediments of Chandrapur Group in the central Indian craton, yielded Rb-Sr internal isochron age of 1641 ± 120 Ma. The high initial 87Sr/86Sr ratio of 0.7098 and ?Ndi value of -3.5 to -3.7 (at 1.6 Ga) is due to contamination of the mantle source magma with the overlying sediments. These dolerites have younger Sm-Nd Model ages (TDM) than Dargawan gabbros as c. 2462-2675 Ma, which is similar to the age of the Sambalpur granite, from which probably sediments to this part of Chattisgarh basin are derived. Hence mixing of sediments with the Damdama dyke during its emplacement, gives rise to high initial 87Sr/86Sr and low initial 143Nd/144 ratios for these dykes. The c. 1600 Ma age indicates minimum age of onset of the sedimentation in the Chandrapur Group of Chattisgarh basin. Both the above mafic intrusions might have taken place in an intracratonic rift related (anorogenic) tectonic setting. This study is the first reliable age report on the onset of sedimentation in the Chandrapur Group. The total minimum time span of Chandrapur and Raipur Group may be 1.6 Ga to 1.0 Ga (Mesoproterozoic). The unconformably underlying Shingora Group of rocks of Chattisgarh Supergroup thus indicates Paleoproterozoic age (older than 1.6 Ga). Most part of the recently classified Chattisgarh Supergroup and Bijawar-Vindhyan sequence are of Mesoproterozoic-Paleoproterozoic age and not of Neoproterozoic-Mesoproterozoic age as considered earlier. Petrographic study of basic dykes from Damdama area (eastern margin of Chattisgarh Supergroup) indicated presence of primary uranium mineral brannerite associated with goethite. This is the evidence of mafic intrusive providing geotherm and helping in scavenging the uranium from the surrounding and later alterations causing remobilisation and reconcentration of pre-existing uranium in host rocks as well as in mafic dyke itself otherwise mafic rocks are poor source of uranium and can not have primary uranium minerals initially. It can be concluded that mafic dykes have role in uranium mineralisation although indirectly. (author)

  17. Establishment of Chinook salmon (Oncorhynchus tshawytscha in Pacific basins of southern South America and its potential ecosystem implications Establecimiento del salmón Chinook (Oncorhynchus tshawytscha en cuencas del Pacífico sur de Sudamérica y sus potenciales implicancias ecosistémicas

    Directory of Open Access Journals (Sweden)

    DORIS SOTO

    2007-03-01

    Full Text Available Salmon and trout species are not native to the southern hemisphere, however rainbow and brown trout have been established a century in southern South America. Yet most attempts to introduce anadromous salmon failed until the onset of aquaculture by 1980. Escapes of Oncorhynchus tshawytscha (Chinook salmon from aquaculture after 1990 have apparently produced increasingly important reproductive returns "naturalized", to upper basins in Chile and Argentina south of 39º S. In this paper we show data on the historic and spatial occurrence of chinook salmon in four Pacific basins during the past decade. Our objective is to establish the progress of the settlement forecasting some ecosystem disruptions in order to project and manage potential impacts. In Chile, sampling took place from 1995 to 2005 including rivers Petrohué, Poicas, and Río Negro-Hornopiren, and Lake Puyehue, in the X Region. In Argentina sampled rivers were Futaleufú, Carrenleufú and Pico. In Chile and Argentina reproductive Chinooks ranged in size between 73 and 130 cm total length, being the smallest sizes those of Lake Puyehue where the population is apparently landlocked. In Río Petrohué, the size of the runs varied from year to year reaching in the peak season of 1996 and 2004 up to 500 kg of fish along 100 m of riverbank. Temporal distribution of juvenile Chinooks suggested mainly a typical ocean type as they are gone to sea within the first year of age. As seen in Petrohue, reproductive populations could import significant quantities of marine derived nutrients as they do in their original habitats thus disturbing natural cycles and balances. Chinook establishment in these pristine watersheds in southern South America poses new challenges for decision makers and fishermen since they may develop a fishery in the Pacific Ocean with consequences to other fishery resources. Additionally they also become a resource for sport fishing. Therefore there is the need of developing management tools and approaches to control the populations avoiding irreversible ecosystem disruptions and social conflictsLos salmonídeos no son nativos del hemisferio sur, y es así que las truchas (arcoiris y café se establecieron en el sur de Sudamérica hace un siglo. La mayoría de los intentos por introducir salmones anádromos falló hasta el establecimiento de la acuicultura en los años ochenta. A partir de 1990, aparentemente debido a escapes de Oncorhynchus tshawytscha (salmón Chinook de cultivo, se están produciendo retornos reproductivos de esta especie en cuencas chilenas y argentinas al sur de los 39º S. En este trabajo se muestra la ocurrencia histórica y espacial de salmón chinook en cuatro cuencas de vertiente Pacífica durante la última década. Nuestro objetivo es establecer el progreso de su establecimiento al tiempo que se proyectan algunos impactos así como alternativas de manejo. En Chile, el muestreo se realizó entre 1995 y 2005 incluyendo los ríos Petrohué, Poicas, Río Negro-Hornopirén, y el Lago Puyehue, en la X Región. En Argentina los ríos muestreados incluyen al Futaleufú, Carrenleufú y Pico. En las cuencas chilenas y argentinas los Chinook reproductivos alcanzaban 73 a 130 cm de largo total encontrándose los más pequeños en el Lago Puyehue donde la población estaría encerrada. En el Río Petrohué, los retornos variaron de año en año alcanzando máximos en 1996 y en el 2004 de hasta 500 kg de pescado en una extensión de 100 m de río. La distribución temporal de juveniles sugiere que principalmente se trata del tipo chinook oceánico ya que migrarían al mar durante el primer año de vida. Como se observa en Petrohué, poblaciones reproductivas de la especie aportarían cantidades relevantes de nutrientes de origen marino tal como ocurre en sus hábitats naturales, produciendo así una importante perturbación a los balances y ciclos naturales en estos sitios. El establecimiento de poblaciones de Chinook en el sur de Sudamérica, genera nuevos desafíos a pescadores y autoridades ya que se podría desar

  18. Establishment of Chinook salmon (Oncorhynchus tshawytscha) in Pacific basins of southern South America and its potential ecosystem implications / Establecimiento del salmón Chinook (Oncorhynchus tshawytscha) en cuencas del Pacífico sur de Sudamérica y sus potenciales implicancias ecosistémicas

    Scientific Electronic Library Online (English)

    DORIS, SOTO; IVÁN, ARISMENDI; CECILIA DI, PRINZIO; FERNANDO, JARA.

    2007-03-01

    Full Text Available Los salmonídeos no son nativos del hemisferio sur, y es así que las truchas (arcoiris y café) se establecieron en el sur de Sudamérica hace un siglo. La mayoría de los intentos por introducir salmones anádromos falló hasta el establecimiento de la acuicultura en los años ochenta. A partir de 1990, a [...] parentemente debido a escapes de Oncorhynchus tshawytscha (salmón Chinook) de cultivo, se están produciendo retornos reproductivos de esta especie en cuencas chilenas y argentinas al sur de los 39º S. En este trabajo se muestra la ocurrencia histórica y espacial de salmón chinook en cuatro cuencas de vertiente Pacífica durante la última década. Nuestro objetivo es establecer el progreso de su establecimiento al tiempo que se proyectan algunos impactos así como alternativas de manejo. En Chile, el muestreo se realizó entre 1995 y 2005 incluyendo los ríos Petrohué, Poicas, Río Negro-Hornopirén, y el Lago Puyehue, en la X Región. En Argentina los ríos muestreados incluyen al Futaleufú, Carrenleufú y Pico. En las cuencas chilenas y argentinas los Chinook reproductivos alcanzaban 73 a 130 cm de largo total encontrándose los más pequeños en el Lago Puyehue donde la población estaría encerrada. En el Río Petrohué, los retornos variaron de año en año alcanzando máximos en 1996 y en el 2004 de hasta 500 kg de pescado en una extensión de 100 m de río. La distribución temporal de juveniles sugiere que principalmente se trata del tipo chinook oceánico ya que migrarían al mar durante el primer año de vida. Como se observa en Petrohué, poblaciones reproductivas de la especie aportarían cantidades relevantes de nutrientes de origen marino tal como ocurre en sus hábitats naturales, produciendo así una importante perturbación a los balances y ciclos naturales en estos sitios. El establecimiento de poblaciones de Chinook en el sur de Sudamérica, genera nuevos desafíos a pescadores y autoridades ya que se podría desarrollar una pesquería de la especie en el océano Pacífico con consecuencias sobre otros recursos pesqueros. Adicionalmente también se transforman en un recuso para la pesca deportiva. Por ello se hace necesario desarrollar herramientas de manejo y control sobre la población para evitar perturbaciones ecológicas y ecosistémicas irreversibles Abstract in english Salmon and trout species are not native to the southern hemisphere, however rainbow and brown trout have been established a century in southern South America. Yet most attempts to introduce anadromous salmon failed until the onset of aquaculture by 1980. Escapes of Oncorhynchus tshawytscha (Chinook [...] salmon) from aquaculture after 1990 have apparently produced increasingly important reproductive returns "naturalized", to upper basins in Chile and Argentina south of 39º S. In this paper we show data on the historic and spatial occurrence of chinook salmon in four Pacific basins during the past decade. Our objective is to establish the progress of the settlement forecasting some ecosystem disruptions in order to project and manage potential impacts. In Chile, sampling took place from 1995 to 2005 including rivers Petrohué, Poicas, and Río Negro-Hornopiren, and Lake Puyehue, in the X Region. In Argentina sampled rivers were Futaleufú, Carrenleufú and Pico. In Chile and Argentina reproductive Chinooks ranged in size between 73 and 130 cm total length, being the smallest sizes those of Lake Puyehue where the population is apparently landlocked. In Río Petrohué, the size of the runs varied from year to year reaching in the peak season of 1996 and 2004 up to 500 kg of fish along 100 m of riverbank. Temporal distribution of juvenile Chinooks suggested mainly a typical ocean type as they are gone to sea within the first year of age. As seen in Petrohue, reproductive populations could import significant quantities of marine derived nutrients as they do in their original habitats thus disturbing natural cycles and balances. Chinook establishment in these pristine watersheds in southern South Ame

  19. PRELIMINARY PALEOMAGNETIC RESULTS FROM OUTFLOW EOCENE-OLIGOCENE ASH FLOW TUFFS FROM THE WESTERN MARGIN OF THE SAN LUIS BASIN: IMPLICATION FOR THE KINEMATIC EVOLUTION OF THE RIO GRANDE RIFT

    Science.gov (United States)

    Mason, S. N.; Geissman, J. W.; Sussman, A. J.

    2009-12-01

    In the Rio Grande rift (RGR), a late Cenozoic continental rift from central Colorado to southern New Mexico, hanging wall margins typically contain en echelon normal fault systems with intervening areas of typically complex structure, called relay zones. Relay zones transfer displacement through complex strain patterns and eventual linkage of faults and hold clues as to how fault zones initiate and grow. The western margin of the RGR at the latitude of the San Luis basin (SLB) exposes laterally continuous Eocene-Oligocene volcanic rocks, well-correlated by 40Ar/39Ar data, and well-preserved rift structures. Ash flow tuffs are usually excellent recorders of the instantaneous geomagnetic field and five ash flow tuffs (ca. 32.3 to 27.3 Ma; including the Saguache Creek, La Jara Canyon, Masonic Park, Fish Canyon, and Carpenter Ridge tuffs) have been sampled in spatial detail along west to east transects of the eastern San Juan volcanic field to the westernmost margin of the RGR at the SLB. Data obtained from our sampling approach will yield a comprehensive definition of relative vertical-axis rotations across the area and will be used to assess the timing of RGR fault linkages. Preliminary paleomagnetic data from the Masonic Park tuff (ca. 28.2 Ma) suggest up to ~17° clockwise rotation between sample locations on the Colorado Plateau and locations to the east, nearest the western margin of the RGR. Preliminary data from the Fish Canyon tuff (ca. 27.8 Ma) show a ~12° clockwise rotation. The relative clockwise vertical-axis rotation of sampling sites in both ash flow tuffs nearest the RGR margin suggests that relay zone development with attending vertical-axis rotation played an important role in the opening of the northern RGR. Our data set is not sufficiently robust at present to test the hypothesis that rotation was taking place concurrently with eruption of these large-volume ash flow tuffs in the early Oligocene, but it is a possibility and if so, the RGR at the latitude of the SLB began to open by about 28 Ma, some 1.5 Ma earlier than previously thought and coeval with late-stage volcanism in the San Juan region.

  20. Determination of groundwater recharge regime and flowpath in the Lower Heihe River basin in an arid area of Northwest China by using environmental tracers: Implications for vegetation degradation in the Ejina Oasis

    International Nuclear Information System (INIS)

    Environmental tracers (CFCs, stable isotopes 18O, 2H, and 3H) and major ions were employed to study river infiltration and groundwater recharge in the aquifer system in the basin of the Lower Heihe River, Northwest China. Three groups of waters have been recognized: (1) young groundwater, connected to the river, with large variation of CFC apparent ages ranging from 18O and ?2H values which are similar to the river water; (2) regional background water, unaffected by the river, having CFC apparent ages >40 a, and being depleted in 18O and 2H compared with the river water; and (3) groundwater in Gurinai, a grassland located about 100 km from the river, in which the predominant discharge is from the Badain Jaran desert, with CFC apparent ages ranging from 25 to >50 a and being enriched in 18O and 2H compared to the river water. The groundwater along the river contains CFCs and 3H down to depths of about 120 m, and the shallow groundwater exhibits CFC apparent ages in a wide range which are not dependent on the well depth. Groundwaters along the river show a similar trend of enrichment in 18O and 2H as the river water whereas groundwaters in depression cones are depleted in heavier isotopes, and have low CFC and 3H concentrations. The CFC apparent age of the groundwater increases with increasing distance downstream, indicating that the dominant part of the groundwater is from infiltration of river water in the upper reaches. Modifications of groundwater recharge are reflected in variations of stable isotope compositions, as well as CFC and 3H concentrations in the groundwater that was recharged from the river over the last decades. Despite recharging from river water, groundwater abstraction has induced a water balance deficit. The riparian ecosystem in the Ejina Oasis is constrained by both decreased river flow and increased groundwater abstraction. The vegetation degradation in the Ejina Oasis is controlled not only by natural aridification but also worsened by heavy groundwater abstraction and decreased river flow.

  1. Positive implicative ordered filters of implicative semigroups

    OpenAIRE

    Kyung Ho Kim; Young Bae Jun

    2000-01-01

    We introduce the notion of positive implicative ordered filters in implicative semigroups. We show that every positive implicative ordered filter is both an ordered filter and an implicative ordered filter. We give examples that an ordered filter (an implicative ordered filter) may not be a positive implicative ordered filter. We also give equivalent conditions of positive implicative ordered filters. Finally we establish the extension property for positive implicative ordered filters.

  2. Extent of Pleistocene lakes in the western Great Basin

    Science.gov (United States)

    Reheis, Marith C.

    1999-01-01

    During the Pliocene to middle Pleistocene, pluvial lakes in the western Great Basin repeatedly rose to levels much higher than those of the well-documented late Pleistocene pluvial lakes, and some presently isolated basins were connected. Sedimentologic, geomorphic, and chronologic evidence at sites shown on the map indicates that Lakes Lahontan and Columbus-Rennie were as much as 70 m higher in the early-middle Pleistocene than during their late Pleistocene high stands. Lake Lahontan at its 1400-m shoreline level would submerge present-day Reno, Carson City, and Battle Mountain, and would flood other now-dry basins. To the east, Lakes Jonathan (new name), Diamond, Newark, and Hubbs also reached high stands during the early-middle(?) Pleistocene that were 25-40 m above their late Pleistocene shorelines; at these very high levels, the lakes became temporarily or permanently tributary to the Humboldt River and hence to Lake Lahontan. Such a temporary connection could have permitted fish to migrate from the Humboldt River southward into the presently isolated Newark Valley and from Lake Lahontan into Fairview Valley. The timing of drainage integration also provides suggested maximum ages for fish to populate the basins of Lake Diamond and Lake Jonathan. Reconstructing and dating these lake levels also has important implications for paleoclimate, tectonics, and drainage evolution in the western Great Basin. For example, shorelines in several basins form a stair-step sequence downward with time from the highest levels, thought to have formed at about 650 ka, to the lowest, formed during the late Pleistocene. This descending sequence indicates progressive drying of pluvial periods, possibly caused by uplift of the Sierra Nevada and other western ranges relative to the western Great Basin. However, these effects cannot account for the extremely high lake levels during the early middle Pleistocene; rather, these high levels were probably due to a combination of increased effective moisture and changes in the size of the Lahontan drainage basin.

  3. Canada Basin revealed

    Science.gov (United States)

    Mosher, David C.; Shimeld, John; Hutchinson, Deborah R.; Chian, D; Lebedeva-Ivanova, Nina; Jackson, Ruth

    2012-01-01

    More than 15,000 line-km of new regional seismic reflection and refraction data in the western Arctic Ocean provide insights into the tectonic and sedimentologic history of Canada Basin, permitting development of new geologic understanding in one of Earth's last frontiers. These new data support a rotational opening model for southern Canada Basin. There is a central basement ridge possibly representing an extinct spreading center with oceanic crustal velocities and blocky basement morphology characteristic of spreading centre crust surrounding this ridge. Basement elevation is lower in the south, mostly due to sediment loading subsidence. The sedimentary succession is thickest in the southern Beaufort Sea region, reaching more than 15 km, and generally thins to the north and west. In the north, grabens and half-grabens are indicative of extension. Alpha-Mendeleev Ridge is a large igneous province in northern Amerasia Basin, presumably emplaced synchronously with basin formation. It overprints most of northern Canada Basin structure. The seafloor and sedimentary succession of Canada Basin is remarkably flat-lying in its central region, with little bathymetric change over most of its extent. Reflections that correlate over 100s of kms comprise most of the succession and on-lap bathymetric and basement highs. They are interpreted as representing deposits from unconfined turbidity current flows. Sediment distribution patterns reflect changing source directions during the basin’s history. Initially, probably late Cretaceous to Paleocene synrift sediments sourced from the Alaska and Mackenzie-Beaufort margins. This unit shows a progressive series of onlap unconformities with a younging trend towards Alpha and Northwind ridges, likely a response to contemporaneous subsidence. Sediment source direction appeared to shift to the Canadian Arctic Archipelago margin for the Eocene and Oligocene, likely due to uplift of Arctic islands during the Eurekan Orogeny. The final stage of sedimentation appears to be from the Mackenzie-Beaufort region for the Miocene and Pliocene when drainage patterns shifted in the Yukon and Alaska to the Mackenzie valley. Upturned reflections at onlap positions may indicate syn-depositional subsidence. There is little evidence, at least at a regional seismic data scale, of contemporaneous or post-depositional sediment reworking, suggesting little large-scale geostrophic or thermohaline-driven bottom current activity.

  4. Detecting runoff variation in Weihe River basin, China

    Science.gov (United States)

    Jingjing, F.; Qiang, H.; Shen, C.; Aijun, G.

    2015-05-01

    Dramatic changes in hydrological factors in the Weihe River basin are analysed. These changes have exacerbated ecological problems and caused severe water shortages for agriculture, industries and the human population in the region, but their drivers are uncertain. The Mann-Kendall test, accumulated departure analysis, sequential clustering and the sliding t-test methods were used to identify the causes of changes in precipitation and runoff in the Weihe basin. Change-points were identified in the precipitation and runoff records for all sub-catchments. For runoff, the change in trend was most pronounced during the 1990s, whereas changes in precipitation were more prominent earlier. The results indicate that human activities have had a greater impact than climate change on the hydrology of the Weihe basin. These findings have significant implications for the establishment of effective strategies to counter adverse effects of hydrological changes in the catchment.

  5. U-Pb and Pb-Pb study of the Murchison Greenstone Belt and of the Evander gold-bearing basin, South Africa. Implications for the evolution of the Kaapvaal craton; Etude U-Pb et Pb-Pb de la Murchison Greenstone Belt et du bassin aurifere d'Evander, Afrique du Sud. Implications pour l'evolution du Kaapvaal craton

    Energy Technology Data Exchange (ETDEWEB)

    Poujol, M

    1997-12-01

    This study presents new U-Pb and Pb-Pb isotopic data for both the Central Rand Group from the Evander Goldfield and the Murchison Greenstone Belt (Republic of South Africa). The Evander Goldfield, where no previous isotopic data have been derived, is located in the eastern side of the Witwatersrand basin. The oldest age measured is ca. 3180 Ma, while the majority of detritus falls in the range 3050-2850 Ma. New growth of zircon (or isotopic resetting of older detritus) appears to have been associated with deposition of the Ventersdorp lavas at ca. 2.7 Ga. A small proportion of the pyrite, mainly extracted from unaltered sediments in the Kimberley Reef footwall, yields ages that are in excess of the minimum depositional age of the Witwatersrand Basin. Authigenic pyrite, as well as detrital grains from highly altered portions of the Kimberley Reef, define two main events. The Pb signature of the 2370 Ma event is probably associated with burial of the basin by the upper portion of the Transvaal sequence, and suggests circulation of highly radiogenic fluids. Isotopic signatures for the 2020 Ma event are probably related to Bushveld intrusion and/or Vredefort catastrophism, and appear to be associate with a fluid that was less radiogenic. The present study shows a number of new results which support a complex, multi-stage evolution and genesis of the Au-U deposits within the Witwatersrand Basin. The Murchison Greenstone Belt constitutes one of the world's largest antimony producing areas and also hosts gold, as well as volcanogenic massive sulfide Cu-Zn mineralization and emeralds. The goal of this study is to determine the age of the belt as well as the timing of mineralization and, also, to assess the potential role of granitoids in the ore-forming processes. The data identify an episode of greenstone formation between 3.09 Ga and 2.97 Ga. Three main magmatic events are identified at ca. 2.97, 2.82 and 2.68 Ga. Pyrites associated with both Sb-Au and Cu-Zn mineralization define a secondary isochron with an age of 2.97 Ga suggesting that they are spatially and genetically associated with the 2.97 Ga Maranda Batholith and the volcanic Rubbervale Formation. Thus, VMS style Cu-Zn mineralization is syn-genetic with respect to the Rubbervale Formation, whereas Sb-Au lode mineralization along the Antimony Line appears to be related to magmatic fluid egress from the Maranda batholith. Pb-Pb signatures of pyrite associated with emerald along the southern flank of the reflect mixing between Pb derived from the older 3.23 Ga basement and the 2.97 Ga magmatic event. The 2.97 Ga Maranda batholith and Rubbervale Formation, therefore, represents a highly prospective metallotect that is relevant, not only to exploration in the Murchison region itself, but to the important question of the source of Witwatersrand gold. (authors)

  6. London Basin Forum

    OpenAIRE

    de Freitas, Michael; Royse, Katherine

    2009-01-01

    Michael de Freitas1 and Katherine Royse2 say geologists and engineers from all backgrounds can now contribute to revealing the nature of the ground beneath London, its geological history, and predicting ground conditions within the Basin. Geoscientist 19.10 October 2009

  7. South Bohemian basins.

    Czech Academy of Sciences Publication Activity Database

    Spudil, J.; Brož, B.; Dašková, Ji?ina; Holcová, K.; Kva?ek, Z.; Pešek, J.; Svobodová, Marcela; Sýkorová, Ivana; Teodoridis, V.

    Prague : Czech Geological Survey, 2014, s. 190-206 ISBN 978-80-7075-862-5 R&D Projects: GA ?R GA105/06/0653 Institutional support: RVO:67985891 ; RVO:67985831 Keywords : Tertiary basins * Czech Republic * Cenomanian and Tertiary lignite * geology * stratigraphy Subject RIV: DB - Geology ; Mineralogy

  8. Evolution and petroleum geology of Amlia and Amukta intra-arc summit basins, Aleutian Ridge

    Science.gov (United States)

    Geist, E.L.; Childs, J. R.; Scholl, D. W.

    1987-01-01

    Amlia and Amukta Basins are the largest of many intra-arc basins formed in late Cenozoic time along the crest of the Aleutian Arc. Both basins are grabens filled with 2-5 km of arc-derived sediment. A complex system of normal faults deformed the basinal strata. Although initial deposits of late Micocene age may be non-marine in origin, by early Pliocene time, most of the basinfill consisted of pelagic and hemipelagic debris and terrigenous turbidite deposits derived from wavebase and subaerial erosion of the arc's crestal areas. Late Cenozoic volcanism along the arc commenced during or shortly after initial subsidence and greatly contributed to active deposition in Amlia and Amukta Basins. Two groups of normal faults occur: major boundary faults common to both basins and 'intra-basin' faults that arise primarily from arc-parallel extension of the arc. The most significant boundary fault, Amlia-Amukta fault, is a south-dipping growth fault striking parallel to the trend of the arc. Displacement across this fault forms a large half-graben that is separated into the two depocentres of Amlia and Amukta Basins by the formation of a late Cenozoic volcanic centre, Seguam Island. Faults of the second group reflect regional deformation of the arc and offset the basement floor as well as the overlying basinal section. Intra-basin faults in Amlia Basin are predominantly aligned normal to the trend of the arc, thereby indicating arc-parallel extension. Those in Amukta basin are aligned in multiple orientations and probably indicate a more complex mechanism of faulting. Displacement across intra-basin faults is attributed to tectonic subsidence of the massif, aided by depositional loading within the basins. In addition, most intra-basin faults are listric and are associated with high growth rates. Although, the hydrocarbon potential of Amlia and Amukta Basins is difficult to assess based on existing data, regional considerations imply that an adequate thermal history conducive to hydrocarbon generation has prevailed during the past 6-5 my. The possibility for source rocks existing in the lower sections of the basins is suggested by exposures of middle and upper Miocene carbonaceous mudstone on nearby Atka Island and the implication that euxinic conditions may have prevailed during the initial formation of the basins. Large structures have evolved to trap migrating hydrocarbons, but questions remain concerning the preservation of primary porosity in a sedimentary section rich in reactive volcaniclastic debris. ?? 1987.

  9. Serenitatis multi-ringed basin

    International Nuclear Information System (INIS)

    New topographic data allow a reassessment of the ring structure of the Serenitatis basin and correlation with the younger Orientale basin. The northern Serenitatis basin is smaller and less well preserved than the southern Serenitatis basin. Three major rings of the main (southern) Serenitatis basin are mapped: ring 1, Linne ring, outlined by mare ridges, average diameter 420 km; ring 2, Haemus ring, outlined by basin-facing scarps and massifs with crenulated borders, 610 km; ring 3, Vitruvius ring, outlined by basin-facing linear scarps and massifs, 880 km. Ring 1 corresponds to the inner Rook Mountain ring of Orientale, ring 2 with the outer Rook ring, and ring 3 with the Cordillera Mountain ring. The ring identifications and assignments indicate that the Serenitatis basin is essentially the same size as the Orientale basin, rather than much larger, as previously proposed. The Apollo 17 site lies near the second ring, which is interpreted as the rim of the transient cavity. Apollo 15 lies at the junction of the Serenitatis and Imbrium third rings; Serenitatis ejecta should be present in significant amounts at the Apollo 15 site. The new reconstruction indicates that portions of the Serenitatis basin are better preserved than previously thought, consistent with recent stratigraphic and sample studies that suggest an age for Serenitatis which is older than, but close to, the time of formation of the Imbrium basin. (Auth.)

  10. Natural frequency of regular basins

    Science.gov (United States)

    Tjandra, Sugih S.; Pudjaprasetya, S. R.

    2014-03-01

    Similar to the vibration of a guitar string or an elastic membrane, water waves in an enclosed basin undergo standing oscillatory waves, also known as seiches. The resonant (eigen) periods of seiches are determined by water depth and geometry of the basin. For regular basins, explicit formulas are available. Resonance occurs when the dominant frequency of external force matches the eigen frequency of the basin. In this paper, we implement the conservative finite volume scheme to 2D shallow water equation to simulate resonance in closed basins. Further, we would like to use this scheme and utilizing energy spectra of the recorded signal to extract resonant periods of arbitrary basins. But here we first test the procedure for getting resonant periods of a square closed basin. The numerical resonant periods that we obtain are comparable with those from analytical formulas.

  11. Identifying Oil Exploration Leads using Intergrated Remote Sensing and Seismic Data Analysis, Lake Sakakawea, Fort Berthold Indian Reservation, Willistion Basin

    Energy Technology Data Exchange (ETDEWEB)

    Scott R. Reeves; Randal L. Billingsley

    2004-02-26

    The Fort Berthold Indian Reservation, inhabited by the Arikara, Mandan and Hidatsa Tribes (now united to form the Three Affiliated Tribes) covers a total area of 1530 mi{sup 2} (980,000 acres). The Reservation is located approximately 15 miles east of the depocenter of the Williston basin, and to the southeast of a major structural feature and petroleum producing province, the Nesson anticline. Several published studies document the widespread existence of mature source rocks, favorable reservoir/caprock combinations, and production throughout the Reservation and surrounding areas indicating high potential for undiscovered oil and gas resources. This technical assessment was performed to better define the oil exploration opportunity, and stimulate exploration and development activities for the benefit of the Tribes. The need for this assessment is underscored by the fact that, despite its considerable potential, there is currently no meaningful production on the Reservation, and only 2% of it is currently leased. Of particular interest (and the focus of this study) is the area under the Lake Sakakawea (formed as result of the Garrison Dam). This 'reservoir taking' area, which has never been drilled, encompasses an area of 150,000 acres, and represents the largest contiguous acreage block under control of the Tribes. Furthermore, these lands are Tribal (non-allotted), hence leasing requirements are relatively simple. The opportunity for exploration success insofar as identifying potential leads under the lake is high. According to the Bureau of Land Management, there have been 591 tests for oil and gas on or immediately adjacent to the Reservation, resulting in a total of 392 producing wells and 179 plugged and abandoned wells, for a success ratio of 69%. Based on statistical probability alone, the opportunity for success is high.

  12. Impact basin relaxation at Iapetus

    Science.gov (United States)

    Robuchon, Guillaume; Nimmo, Francis; Roberts, James; Kirchoff, Michelle

    2011-07-01

    We investigate impact basin relaxation on Iapetus by combining a 3D thermal evolution model (Robuchon, G., Choblet, G., Tobie, G., Cadek, O., Sotin, C., Grasset, O. [2010]. Icarus 207, 959-971) with a spherical axisymmetric viscoelastic relaxation code (Zhong, S., Paulson, A., Wahr, J. [2003]. Geophys. J. Int. 155, 679-695). Due to the progressive cooling of Iapetus, younger basins relax less than older basins. For an ice reference viscosity of 10 14 Pa s, an 800 km diameter basin relaxes by 30% if it formed in the first 50 Myr but by 10% if it formed at 1.2 Gyr. Bigger basins relax more rapidly than smaller ones, because the inferred thickness of the ice shell exceeds the diameter of all but the largest basins considered. Stereo topography shows that all basins 600 km in diameter or smaller are relaxed by 25% or less. Our model can match the relaxation of all the basins considered, within error, by assuming a single basin formation age (4.36 Ga for our nominal viscosity). This result is consistent with crater counts, which show no detectable age variation between the basins examined.

  13. Caribbean basin framework, 3: Southern Central America and Colombian basin

    Energy Technology Data Exchange (ETDEWEB)

    Kolarsky, R.A.; Mann, P. (Univ. of Texas, Austin (United States))

    1991-03-01

    The authors recognize three basin-forming periods in southern Central America (Panama, Costa Rica, southern Nicaragua) that they attempt to correlate with events in the Colombian basin (Bowland, 1984): (1) Early-Late Cretaceous island arc formation and growth of the Central American island arc and Late Cretaceous formation of the Colombian basin oceanic plateau. During latest Cretaceous time, pelagic carbonate sediments blanketed the Central American island arc in Panama and Costa Rica and elevated blocks on the Colombian basin oceanic plateau; (2) middle Eocene-middle Miocene island arc uplift and erosion. During this interval, influx of distal terrigenous turbidites in most areas of Panama, Costa Rica, and the Colombian basin marks the uplift and erosion of the Central American island arc. In the Colombian basin, turbidites fill in basement relief and accumulate to thicknesses up to 2 km in the deepest part of the basin. In Costa Rica, sedimentation was concentrated in fore-arc (Terraba) and back-arc (El Limon) basins; (3) late Miocene-Recent accelerated uplift and erosion of segments of the Central American arc. Influx of proximal terrigenous turbidites and alluvial fans in most areas of Panama, Costa Rica, and the Colombian basin marks collision of the Panama arc with the South American continent (late Miocene early Pliocene) and collision of the Cocos Ridge with the Costa Rican arc (late Pleistocene). The Cocos Ridge collision inverted the Terraba and El Limon basins. The Panama arc collision produced northeast-striking left-lateral strike-slip faults and fault-related basins throughout Panama as Panama moved northwest over the Colombian basin.

  14. Basin Hopping Graph

    DEFF Research Database (Denmark)

    Kucharik, Marcel; Hofacker, Ivo; Stadler, Peter; Qin, Jing

    2014-01-01

    Motivation RNA folding is a complicated kinetic process. The minimum free energy structure provides only a static view of the most stable conformational state of the system. It is insufficient to give detailed insights into the dynamic behavior of RNAs. A sufficiently sophisticated analysis of the folding free energy landscape, however, can provide the relevant information. Results We introduce the basin hopping graph (BHG) as a novel coarse-grained model of folding landscapes. Each vertex of th...

  15. Organic geochemistry of the Callovo-Oxfordian argillo-carbonated sedimentary series of the East of the Paris basin and of England. Variabilities and paleo-environmental implications; Geochimie organique des series argilo-carbonatees du Callovo-Oxfordien de l'Est du bassin de Paris et d'Angleterre: Variabilites et implications paleoenvironnementales

    Energy Technology Data Exchange (ETDEWEB)

    Hautevelle, Y

    2005-12-15

    The Callovo-Oxfordian clay-stones from the East of the Paris basin are studied by ANDRA in order to test the feasibility of a possible storage of radioactive waste. The molecular analysis of their organic matter indicates that they can be considered as homogenous from their organic content point of view because they are characterized by only one molecular facies. However, the transition to the surrounding limestones is underlined by a major evolution of the molecular facies indicating a change and an increase of the variability of the deposition and diagenesis conditions. The evolution of the distribution of the plant bio-markers indicates, at the end of the Lower Oxfordian, a paleo-floristic change characterized by the increase of the proportion of Pinaceae (a conifer family) or their forerunners on the London-Brabant massif. This paleo-floristic evolution reflects a paleo-climatic change characterized by the increase of aridity at the global scale. Other complementary results get on other sedimentary series of similar ages highlight the occurrence of a period of water anoxia during the Middle Callovian which certainly happened on the major part of the Western Europe. This event could be at the origin of the crisis of the carbonate production at the Dogger/Malm transition. On the other hand, an experimental technique based on artificial maturation of extant plants has been developed and will allow the acquisition of new palaeo-chemo-taxonomic data. These data will contribute to a better interpretation of plant bio-marker assemblages in terms of palaeo-floristic composition. (author)

  16. Estancia Basin dynamic water budget.

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, Richard P.

    2004-09-01

    The Estancia Basin lies about 30 miles to the east of Albuquerque, NM. It is a closed basin in terms of surface water and is somewhat isolated in terms of groundwater. Historically, the primary natural outlet for both surface water and groundwater has been evaporation from the salt lakes in the southeastern portion of the basin. There are no significant watercourses that flow into this basin and groundwater recharge is minimal. During the 20th Century, agriculture grew to become the major user of groundwater in the basin. Significant declines in groundwater levels have accompanied this agricultural use. Domestic and municipal use of the basin groundwater is increasing as Albuquerque population continues to spill eastward into the basin, but this use is projected to be less than 1% of agricultural use well into the 21st Century. This Water Budget model keeps track of the water balance within the basin. The model considers the amount of water entering the basin and leaving the basin. Since there is no significant surface water component within this basin, the balance of water in the groundwater aquifer constitutes the primary component of this balance. Inflow is based on assumptions for recharge made by earlier researchers. Outflow from the basin is the summation of the depletion from all basin water uses. The model user can control future water use within the basin via slider bars that set values for population growth, water system per-capita use, agricultural acreage, and the types of agricultural diversion. The user can also adjust recharge and natural discharge within the limits of uncertainty for those parameters. The model runs for 100 years beginning in 1940 and ending in 2040. During the first 55 years model results can be compared to historical data and estimates of groundwater use. The last 45 years are predictive. The model was calibrated to match to New Mexico Office of State Engineer (NMOSE) estimates of aquifer storage during the historical period by making adjustments to recharge and outflow that were within the parameters uncertainties. Although results of this calibrated model imply that there may be more water remaining in the aquifer than the Estancia Water Plan estimates, this answer is only another possible result in a range of answers that are based on large parameter uncertainties.

  17. Advanced Chemistry Basins Model

    Energy Technology Data Exchange (ETDEWEB)

    Blanco, Mario; Cathles, Lawrence; Manhardt, Paul; Meulbroek, Peter; Tang, Yongchun

    2003-02-13

    The objective of this project is to: (1) Develop a database of additional and better maturity indicators for paleo-heat flow calibration; (2) Develop maturation models capable of predicting the chemical composition of hydrocarbons produced by a specific kerogen as a function of maturity, heating rate, etc.; assemble a compositional kinetic database of representative kerogens; (3) Develop a 4 phase equation of state-flash model that can define the physical properties (viscosity, density, etc.) of the products of kerogen maturation, and phase transitions that occur along secondary migration pathways; (4) Build a conventional basin model and incorporate new maturity indicators and data bases in a user-friendly way; (5) Develop an algorithm which combines the volume change and viscosities of the compositional maturation model to predict the chemistry of the hydrocarbons that will be expelled from the kerogen to the secondary migration pathways; (6) Develop an algorithm that predicts the flow of hydrocarbons along secondary migration pathways, accounts for mixing of miscible hydrocarbon components along the pathway, and calculates the phase fractionation that will occur as the hydrocarbons move upward down the geothermal and fluid pressure gradients in the basin; and (7) Integrate the above components into a functional model implemented on a PC or low cost workstation.

  18. Aquatic risk assessment of priority and other river basin specific pesticides in surface waters of Mediterranean river basins.

    Science.gov (United States)

    Silva, Emília; Daam, Michiel A; Cerejeira, Maria José

    2015-09-01

    To meet good chemical and ecological status, Member States are required to monitor priority substances and chemicals identified as substances of concern at European Union and local/river-basin/national level, respectively, in surface water bodies, and to report exceedances of the environmental quality standards (EQSs). Therefore, standards have to be set at national level for river basin specific pollutants. Pesticides used in dominant crops of several agricultural areas within the catchment of Mediterranean river basins ('Mondego', 'Sado' and 'Tejo', Portugal) were selected for monitoring, in addition to the pesticides included in priority lists defined in Europe. From the 29 pesticides and metabolites selected for the study, 20 were detected in surface waters of the river basins, seven of which were priority substances: alachlor, atrazine, chlorfenvinphos, chlorpyrifos, endosulfan, simazine and terbutryn, all of which exceeded their respective EQS values. QSs for other specific pollutants were calculated using different extrapolation techniques (i.e. deterministic or probabilistic) largely based on the method described in view of the Water Framework Directive. Non-acceptable aquatic risks were revealed for molinate, oxadiazon, pendimethalin, propanil, terbuthylazine, and the metabolite desethylatrazine. Implications of these findings for the classification of the ecological status of surface water bodies in Portugal and at the European level are discussed. PMID:26002046

  19. K-Basins design guidelines

    International Nuclear Information System (INIS)

    The purpose of the design guidelines is to enable SNF and K Basin personnel to complete fuel and sludge removal, and basin water mitigation by providing engineering guidance for equipment design for the fuel basin, facility modifications (upgrades), remote tools, and new processes. It is not intended to be a purchase order reference for vendors. The document identifies materials, methods, and components that work at K Basins; it also Provides design input and a technical review process to facilitate project interfaces with operations in K Basins. This document is intended to compliment other engineering documentation used at K Basins and throughout the Spent Nuclear Fuel Project. Significant provisions, which are incorporated, include portions of the following: General Design Criteria (DOE 1989), Standard Engineering Practices (WHC-CM-6-1), Engineering Practices Guidelines (WHC 1994b), Hanford Plant Standards (DOE-RL 1989), Safety Analysis Manual (WHC-CM-4-46), and Radiological Design Guide (WHC 1994f). Documents (requirements) essential to the engineering design projects at K Basins are referenced in the guidelines

  20. K-Basins design guidelines

    Energy Technology Data Exchange (ETDEWEB)

    Roe, N.R.; Mills, W.C.

    1995-06-01

    The purpose of the design guidelines is to enable SNF and K Basin personnel to complete fuel and sludge removal, and basin water mitigation by providing engineering guidance for equipment design for the fuel basin, facility modifications (upgrades), remote tools, and new processes. It is not intended to be a purchase order reference for vendors. The document identifies materials, methods, and components that work at K Basins; it also Provides design input and a technical review process to facilitate project interfaces with operations in K Basins. This document is intended to compliment other engineering documentation used at K Basins and throughout the Spent Nuclear Fuel Project. Significant provisions, which are incorporated, include portions of the following: General Design Criteria (DOE 1989), Standard Engineering Practices (WHC-CM-6-1), Engineering Practices Guidelines (WHC 1994b), Hanford Plant Standards (DOE-RL 1989), Safety Analysis Manual (WHC-CM-4-46), and Radiological Design Guide (WHC 1994f). Documents (requirements) essential to the engineering design projects at K Basins are referenced in the guidelines.

  1. Isomorphic Implication

    OpenAIRE

    Bauland, Michael; Hemaspaandra, Edith

    2004-01-01

    We study the isomorphic implication problem for Boolean constraints. We show that this is a natural analog of the subgraph isomorphism problem. We prove that, depending on the set of constraints, this problem is in P, NP-complete, or NP-hard, coNP-hard, and in parallel access to NP. We show how to extend the NP-hardness and coNP-hardness to hardness for parallel access to NP for some cases, and conjecture that this can be done in all cases.

  2. Aleutian basin oceanic crust

    Science.gov (United States)

    Christeson, Gail L.; Barth, Ginger A.

    2015-01-01

    We present two-dimensional P-wave velocity structure along two wide-angle ocean bottom seismometer profiles from the Aleutian basin in the Bering Sea. The basement here is commonly considered to be trapped oceanic crust, yet there is a change in orientation of magnetic lineations and gravity features within the basin that might reflect later processes. Line 1 extends ?225 km from southwest to northeast, while Line 2 extends ?225 km from northwest to southeast and crosses the observed change in magnetic lineation orientation. Velocities of the sediment layer increase from 2.0 km/s at the seafloor to 3.0–3.4 km/s just above basement, crustal velocities increase from 5.1–5.6 km/s at the top of basement to 7.0–7.1 km/s at the base of the crust, and upper mantle velocities are 8.1–8.2 km/s. Average sediment thickness is 3.8–3.9 km for both profiles. Crustal thickness varies from 6.2 to 9.6 km, with average thickness of 7.2 km on Line 1 and 8.8 km on Line 2. There is no clear change in crustal structure associated with a change in orientation of magnetic lineations and gravity features. The velocity structure is consistent with that of normal or thickened oceanic crust. The observed increase in crustal thickness from west to east is interpreted as reflecting an increase in melt supply during crustal formation.

  3. Western Canada Sedimentary Basin competitiveness

    International Nuclear Information System (INIS)

    Recent dramatic expansion of the natural gas industry in the Western Canada Sedimentary Basin provided ample proof of the potential of this area for further development of natural gas supply. However, the inherent competitive advantages provided by the Western Canada Sedimentary Basin were said to have been offset by low netback prices resulting in poor producer economics when competitiveness is measured by availability of opportunities to find and develop gas supply at costs low enough to ensure attractive returns. Technology was identified as one of the key elements in improving basin competitiveness, but the greatest potential lies in reduced transportation costs and increased access to North American market centres. 8 figs

  4. U.S. Geological Survey and Bureau of Land Management Cooperative Coalbed Methane Project in the Powder River Basin, Wyoming

    Science.gov (United States)

    U.S. Geological Survey

    2006-01-01

    Introduction: Evidence that earthquakes threaten the Mississippi, Ohio, and Wabash River valleys of the Central United States abounds. In fact, several of the largest historical earthquakes to strike the continental United States occurred in the winter of 1811-1812 along the New Madrid seismic zone, which stretches from just west of Memphis, Tenn., into southern Illinois (fig. 1). Several times in the past century, moderate earthquakes have been widely felt in the Wabash Valley seismic zone along the southern border of Illinois and Indiana (fig. 1). Throughout the region, between 150 and 200 earthquakes are recorded annually by a network of monitoring instruments, although most are too small to be felt by people. Geologic evidence for prehistoric earthquakes throughout the region has been mounting since the late 1970s. But how significant is the threat? How likely are large earthquakes and, more importantly, what is the chance that the shaking they cause will be damaging?The Bureau of Land Management (BLM) Wyoming Reservoir Management Group and the U.S. Geological Survey (USGS) began a cooperative project in 1999 to collect technical and analytical data on coalbed methane (CBM) resources and quality of the water produced from coalbeds in the Wyoming part of the Powder River Basin. The agencies have complementary but divergent goals and these kinds of data are essential to accomplish their respective resource evaluation and management tasks. The project also addresses the general public need for information pertaining to Powder River Basin CBM resources and development. BLM needs, which relate primarily to the management of CBM resources, include improved gas content and gas in-place estimates for reservoir characterization and resource/reserve assessment, evaluation, and utilization. USGS goals include a basinwide assessment of CBM resources, an improved understanding of the nature and origin of coalbed gases and formation waters, and the development of predictive models for the assessment of CBM resources that can be used for such purposes in other basins in the United States (for example, the Bighorn, Greater Green River, and Williston Basins) and in other countries throughout the world (for example, Indonesia, New Zealand, and the Philippines). Samples of coal, produced water, and gas from coalbed methane drill holes throughout the Powder River Basin, many of which are adjacent to several active mine areas (figs. 1, 2), have been collected by personnel in the USGS, BLM Reservoir Management Group, and Casper and Buffalo BLM Field Offices. Sampling was done under confidentiality agreements with 29 participating CBM companies and operators. Analyses run on the samples include coal permeability, coal quality and chemistry, coal petrography and petrology, methane desorption and adsorption, produced-water chemistry, and gas composition and isotopes. The USGS has supplied results to the BLM Reservoir Management Group for their resource management needs, and data are released when the terms of the confidentiality agreements are completed and consent is obtained.

  5. Sedimentary basins classification: a commented review; Classificacao de bacias sedimentares: uma revisao comentada

    Energy Technology Data Exchange (ETDEWEB)

    Martins-Neto, Marcelo A. [Universidade Federal de Ouro Preto (UFOP), MG (Brazil). Nucleo de Geologia do Petroleo; Fundacao Gorceix, Ouro Preto, MG (Brazil)]. E-mail: marcelo@nupetro.com.br

    2006-03-15

    During the evolution of the knowledge regarding sedimentary basins, many authors have discussed criteria and proposed schemes for their classification, most of them driven by geo tectonic theories like Geossinclinal and Plate Tectonics. Firstly, the present paper discusses the definition of a sedimentary basin, since there are two different approaches in the literature. The first is based on geo dynamic criteria, where basins are defined by their linked subsidence mechanisms, related to a single tectonic regime or tectonic-thermal event, responsible for the development of a first-order basin cycle. According to the second approach, a basin is defined as a region characterized by the accumulation of a thick sedimentary package during a long time span, regardless the existence of significant hiatuses and/or unconformities inside the package and the stacking of more than one first-order cycle. After a historical synthesis about the classification of sedimentary basins, the merits and efficiency of classification proposals are discussed, including the particular case of the intracratonic basins, as well as perspectives for the future. It is concluded that the basic classification criteria proposed by Dickinson (1974), although incomplete and/or deficient in some aspects, are very efficient for practical purposes, mostly by emphasizing the type of plate interaction (tectonic regime) during sedimentation (if divergent, convergent or strike-slip). The approach explaining the evolution of basins based on plate interactions solved the major problem of the previous classification schemes that was the proliferation of names for particular cases, as well as has direct implications in terms of stress field, structural and stratigraphic styles, being very efficient in the definition of the type of basin and having a predictive character in terms of processes and products. (author)

  6. RESERVES IN WESTERN BASINS PART IV: WIND RIVER BASIN

    Energy Technology Data Exchange (ETDEWEB)

    Robert Caldwell

    1998-04-01

    Vast quantities of natural gas are entrapped within various tight formations in the Rocky Mountain area. This report seeks to quantify what proportion of that resource can be considered recoverable under today's technological and economic conditions and discusses factors controlling recovery. The ultimate goal of this project is to encourage development of tight gas reserves by industry through reducing the technical and economic risks of locating, drilling and completing commercial tight gas wells. This report is the fourth in a series and focuses on the Wind River Basin located in west central Wyoming. The first three reports presented analyses of the tight gas reserves and resources in the Greater Green River Basin (Scotia, 1993), Piceance Basin (Scotia, 1995) and the Uinta Basin (Scotia, 1995). Since each report is a stand-alone document, duplication of language will exist where common aspects are discussed. This study, and the previous three, describe basin-centered gas deposits (Masters, 1979) which contain vast quantities of natural gas entrapped in low permeability (tight), overpressured sandstones occupying a central basin location. Such deposits are generally continuous and are not conventionally trapped by a structural or stratigraphic seal. Rather, the tight character of the reservoirs prevents rapid migration of the gas, and where rates of gas generation exceed rates of escape, an overpressured basin-centered gas deposit results (Spencer, 1987). Since the temperature is a primary controlling factor for the onset and rate of gas generation, these deposits exist in the deeper, central parts of a basin where temperatures generally exceed 200 F and drill depths exceed 8,000 feet. The abbreviation OPT (overpressured tight) is used when referring to sandstone reservoirs that comprise the basin-centered gas deposit. Because the gas resources trapped in this setting are so large, they represent an important source of future gas supply, prompting studies to understand and quantify the resource itself and to develop technologies that will permit commercial exploitation. This study is a contribution to that process.

  7. Geology, exploration status of Uruguay's sedimentary basins

    Energy Technology Data Exchange (ETDEWEB)

    Goso, C.; Santa Ana, H. de (Administracion Nacional de Combustibles, Alcohol y Portland (Uruguay))

    1994-02-07

    This article attempts to present the geological characteristics and tectonic and sedimentary evolution of Uruguayan basins and the extent to which they have been explored. Uruguay is on the Atlantic coast of South America. The country covers about 318,000 sq km, including offshore and onshore territories corresponding to more than 65% of the various sedimentary basins. Four basins underlie the country: the Norte basin, the Santa Lucia basin, the offshore Punta del Este basin, and the offshore-onshore Pelotas-Merin basin. The Norte basin is a Paleozoic basin while the others are Mesozoic basins. Each basin has been explored to a different extent, as this paper explains.

  8. A review of bovine tuberculosis in the kafue basin ecosystem.

    Science.gov (United States)

    Munyeme, Musso; Munang'andu, Hetron Mweemba

    2011-01-01

    The Kafue basin ecosystem is the only remaining natural habitat for the endangered Kafue lechwe antelope (Kobus leche Kafuensis). However, hydroelectricity power production, large-scale sugar plantations, commercial fishing and increasing livestock production are threatening its natural existence and sustainability. Further, increasing human settlements within and around the Kafue basin have resulted in decreased grazing grounds for the Kafue lechwe antelopes despite a corresponding increase in cattle population sharing the same pasture. Baseline epidemiological data have persistently reported findings of bovine tuberculosis (BTB) in both wild and domestic animals, although these have been deficient in terms of describing direct evidence in the role of either lechwe antelopes or cattle in the reported observations. Despite the current literature being deficient in establishing the casual role and transmission patterns of BTB, a bimodal route of infection at the livestock/wildlife interface has been postulated. Likewise, it is not known how much of (BTB) has the potential of causing disease in humans. This paper, seeks to underline those aspects that need further research and update available data on BTB in the Kafue basin with regards to the prevalence, distribution, risk factors, threats on wildlife conservation, livestock production, public health implications, and possible mitigatory measures. PMID:21547232

  9. Great Basin Integrated Landscape Monitoring Pilot Summary Report

    Science.gov (United States)

    Finn, Sean P.; Kitchell, Kate; Baer, Lori Anne; Bedford, David R.; Brooks, Matthew L.; Flint, Alan L.; Flint, Lorraine E.; Matchett, J.R.; Mathie, Amy; Miller, David M.; Pilliod, David S.; Torregrosa, Alicia; Woodward, Andrea

    2010-01-01

    The Great Basin Integrated Landscape Monitoring Pilot project (GBILM) was one of four regional pilots to implement the U.S. Geological Survey (USGS) Science Thrust on Integrated Landscape Monitoring (ILM) whose goal was to observe, understand, and predict landscape change and its implications on natural resources at multiple spatial and temporal scales and address priority natural resource management and policy issues. The Great Basin is undergoing rapid environmental change stemming from interactions among global climate trends, increasing human populations, expanding and accelerating land and water uses, invasive species, and altered fire regimes. GBLIM tested concepts and developed tools to store and analyze monitoring data, understand change at multiple scales, and forecast landscape change. The GBILM endeavored to develop and test a landscape-level monitoring approach in the Great Basin that integrates USGS disciplines, addresses priority management questions, catalogs and uses existing monitoring data, evaluates change at multiple scales, and contributes to development of regional monitoring strategies. GBILM functioned as an integrative team from 2005 to 2010, producing more than 35 science and data management products that addressed pressing ecosystem drivers and resource management agency needs in the region. This report summarizes the approaches and methods of this interdisciplinary effort, identifies and describes the products generated, and provides lessons learned during the project.

  10. Testing for Basins of Wada.

    Science.gov (United States)

    Daza, Alvar; Wagemakers, Alexandre; Sanjuán, Miguel A F; Yorke, James A

    2015-01-01

    Nonlinear systems often give rise to fractal boundaries in phase space, hindering predictability. When a single boundary separates three or more different basins of attraction, we say that the set of basins has theWada property and initial conditions near that boundary are even more unpredictable. Many physical systems of interest with this topological property appear in the literature. However, so far the only approach to study Wada basins has been restricted to two-dimensional phase spaces. Here we report a simple algorithm whose purpose is to look for the Wada property in a given dynamical system. Another benefit of this procedure is the possibility to classify and study intermediate situations known as partially Wada boundaries. PMID:26553444

  11. Hydrologic Sub-basins of Greenland

    Data.gov (United States)

    National Aeronautics and Space Administration — The Hydrologic Sub-basins of Greenland data set contains Geographic Information System (GIS) polygon shapefiles that include 293 hydrologic sub-basins of the...

  12. WATSTORE Stream Flow Basin Characteristics File

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Stream Flow Basin Characteristics file contains information about the drainage basins of selected USGS gaging stations. Data elements of this file were...

  13. On the Origin of Cratonic Sag Basins: Did They Sag?

    Science.gov (United States)

    Morgan, Jason P.

    2015-04-01

    Cratonic sag basins are regions of long-lived, extremely slow (~20-30 m/Myr) shallow water and terrestrial sediment accumulation that have no striking signs of tectonic activity (cf. Allen and Armitage, 2012). In their evolution, hundreds of Myr-long periods of slow sediment accumulation are separated by unconformities. The mechanisms for their formation resist geodynamic characterization by other common hypotheses for basin subsidence because of their extremely slow subsidence and lack of evident tectonic activity. I propose their dynamics are better understood within the geodynamic context of continental cratons that ride over a ~250km-deep sub-asthenospheric mantle with lateral temperature variations between a few wide and persistent 1000s-km broad ~1400C 'superplume' upwelling mantle structures (e.g. currently beneath S. African Atlantic and French Polynesia) and prevalent surrounding ~1150C average temperature sub-asthenospheric mantle. When continents pass over typical mantle plumes, buoyant plume material tends to drain beneath the continent along junctions between cratons where the lithosphere is relatively thin, keeping the lithosphere over regions where plume material drains hotter than the average temperature of ~250km-deep mantle. (e.g., the Cameroon Line.) Regions where melting of plume material occurs during decompression associated with either plume ascent or lateral drainage beneath continents are associated with the addition of a buoyant rind of more depleted mantle to the continent. In addition, regions where plume material can pond in a relatively thin sub-lithospheric 'anti-basin' beneath a continent, or that stay stationary for long times over super plumes will heat to a lithospheric basal temperature of ~1400C instead of ~1150C, with ~700m of associated uplift. (e.g., Southern Africa). In this scenario (cf. Yamamoto, Morgan, and Morgan in "Plumes, Plates, and Paradigms"), it is the relative plume-passage-induced uplift of arches between cratonic sag basins, and relative coldness of the base of the cratonic lithosphere beneath sag basins that is the origin of the obvious 'sag' in the interiors of cratonic sag basins. The thermal time-scales of these plume-related processes can account for both the slow background subsidence of cratonic sag basins linked to cooling of a cratonic root following its (rare) incubation over a superplume, and faster subsidence pulses linked to more transient plume-related (or subduction-linked dynamic topography) effects. In this framework, the flexure in cratonic sag basins is not due to anomalous sag in their interior, but rather 'anomalous' push-up of their margins. A final interesting consequence is that the deposition of thick sequences of sediments with higher-than-average radiogenic production can - again after ~100s of Ma -- change the long-term sub-basin temperature profile, hence the relative elevation of the basin's center. Simple thermal models are discussed to quantify and illustrate these implications.

  14. Stress inversion and basement-cover stress transmission across weak layers in the Paris basin, France

    Science.gov (United States)

    Gunzburger, Yann; Magnenet, Vincent

    2014-03-01

    We investigate the source of non-purely gravitational horizontal stresses in the Paris basin, a nowadays tectonically quiet intracratonic basin, in its eastern border of which outstandingly dense stress measurements are available. Based on a synthesis of published data, the stress state in the basin is first shown to be very close to the one that may be extrapolated for the underlying basement, in terms of principal stress orientations and horizontal to vertical stress ratios. This is in favour of a mechanical coupling between the basement and its sedimentary cover, which may seem contradictory to the presence of several weak rock layers in the basin fill, e.g. an argillite layer that was shown to bear low deviatoric stresses, and salt layers that are implicated in a major décollement elsewhere. To unravel this apparent contradiction, a 3D-numerical modelling is performed, following a rigorous inverse problem approach, to determine the long-term elastic properties of both the basement and the basin rocks. The objective is to find the set of elastic constants that provides the best fit between the calculated stress state in the basin and the in situ data, by assuming that the stress state in the basement is known. This methodology provides a realistic set of mechanical parameters, in agreement with previous studies, which leads to the conclusion that the horizontal stresses in the basin constitute its mechanical response to the stresses that developed in the underlying basement during and since the last tectonic event (Alpine phase). The fact that horizontal stresses could be transmitted across the weak horizons, contrary to what may be expected at first glance, is explained both by the geometry of the basin and the fact that, over the long term, the stiffnesses of the various sedimentary rocks are only slightly different from each other.

  15. Capture basin approximation using interval analysis

    OpenAIRE

    Lhommeau, Mehdi; Jaulin, Luc; Hardouin, Laurent

    2011-01-01

    This paper proposes a new approach for computing the capture basin C of a target T. The capture basin corresponds to the set of initial state vectors such that the target could be reached in finite time via an appropriate control input, before possibly leaving the target. Whereas classical capture basin characterization does not provide any guarantee on the set of state vectors that belong to the capture basin, interval analysis and guaranteed numerical integration allow us to avoid any indet...

  16. Krušné hory Piedmont basins. Sokolov Basin.

    Czech Academy of Sciences Publication Activity Database

    Rojík, P.; Dašková, Ji?ina; Kva?ek, Z.; Pešek, J.; Sýkorová, Ivana; Teodoridis, V.

    Prague : Czech Geological Survey, 2014, s. 90-142 ISBN 978-80-7075-862-5 R&D Projects: GA ?R GA105/06/0653 Institutional support: RVO:67985891 ; RVO:67985831 Keywords : Tertiary basins * Czech Republic * Cenomanian and Tertiary lignite * geology * stratigraphy Subject RIV: DB - Geology ; Mineralogy

  17. Supplementary information on K-Basin sludges

    International Nuclear Information System (INIS)

    Three previous documents in this series have been published covering the analysis of: K East Basin Floor and Pit Sludge, K East Basin Canister Sludge, and K West Basin Canister Sludge. Since their publication, additional data have been acquired and analyses performed. It is the purpose of this volume to summarize the additional insights gained in the interim time period

  18. Supplementary information on K-Basin sludges

    Energy Technology Data Exchange (ETDEWEB)

    MAKENAS, B.J.

    1999-03-15

    Three previous documents in this series have been published covering the analysis of: K East Basin Floor and Pit Sludge, K East Basin Canister Sludge, and K West Basin Canister Sludge. Since their publication, additional data have been acquired and analyses performed. It is the purpose of this volume to summarize the additional insights gained in the interim time period.

  19. XXI Century Climatology of Snow Cover for the Western River Basins of the Indus River System

    CERN Document Server

    Hasson, Shabeh ul; Lucarini, Valerio

    2012-01-01

    Under changing climate, freshwater resources of Hindu Kush-Karakoram-Himalaya (HKH) region can be affected by changes in temperature and in amount, type and distribution of precipitation. This can have serious implications for the water supply and in turn threaten the food security and economic wellbeing of Indus basin. Using MODIS daily snow products (Terra & Aqua), this study focuses on the assessment of the 2000-2010 snow cover dynamics on seasonal/annual basis against geophysical parameters (aspect, elevation and slope) for the so called western river basins of Indus River System (IRS), namely Indus, Kabul, Jhelum, Astore, Gilgit, Hunza, Swat, Shigar and Shyok basins. Results show that inputs from MODIS instrument provide unprecedented better opportunity to study by using GIS techniques the snow cover dynamics in the remote areas like HKH region at such hyper-temporal and finer planar resolution. Adapted non-spectral cloud filtering techniques have significantly reduced cloud coverage and improved sno...

  20. K Basin spent fuel sludge treatment alternatives study. Volume 2, Technical options

    International Nuclear Information System (INIS)

    Approximately 2100 metric tons of irradiated N Reactor fuel are stored in the KE and KW Basins at the Hanford Site, Richland, Washington. Corrosion of the fuel has led to the formation of sludges, both within the storage canisters and on the basin floors. Concern about the degraded condition of the fuel and the potential for leakage from the basins in proximity to the Columbia River has resulted in DOE's commitment in the Tri-Party Agreement (TPA) to Milestone M-34-00-T08 to remove the fuel and sludges by a December 2002 target date. To support the planning for this expedited removal action, the implications of sludge management under various scenarios are examined. This report, Volume 2 of two volumes, describes the technical options for managing the sludges, including schedule and cost impacts, and assesses strategies for establishing a preferred path

  1. What Controls Runoff Ratios in the Congo Basin?

    Science.gov (United States)

    Durand, M. T.; Wei, R.

    2014-12-01

    As the second-largest river globally, the Congo is a critical part of large-scale water, energy, and carbon cycles, and thus has a significant influence on regional climate. The runoff ratio is a coefficient relating runoff to precipitation; it is a parameter that integrates and summarizes upstream hydrologic processes. The Budyko equation depicts the expected partitioning of precipitation (P) into evapotranspiration (E) and runoff (R): P=R+E. It is hypothesized that radiation and precipitation are primary controls of the partitioning process; the effects of the surface control (e.g. soil and slope) are implicitly assumed to be minor. In this study, we explored thirty years of data in the Congo River basin. We will correlate the runoff ratio to a variety of factors, including precipitation, radiation and surface controls (e.g. soil, slope). Global Precipitation Climatology Project (GPCP) by pentad precipitation was used as primary precipitation data, and Climatic Research Unit (CRU) by data was used for comparison. For discharge and drainage area were derived from Global Runoff Data Centre (GRDC), and net radiation is from NASA Earth Observatory. Congo sub basins are analyzed as well. Interannual variability in the runoff ratio for the Congo basin ranged from 0.2 to 0.3, but was generally uncorrelated with precipitation. Runoff is generally uncorrelated with precipitation, whereas evapotranspiration calculated as residual (P-R) is highly correlated with precipitation, with E ranging from 1000 to 1300 mm per year, and P explaining 85% of the variance. Spatial variability was explored by analysis of long-term mean runoff ratio for 10 sub-basins. Spatially, both R and runoff ratio are highly correlated with P, with P explaining 59% of the variance in the runoff ratio. Physical mechanisms to explain these results are explored, and the implications for the Congo's role in partitioning rainfall over sub-Saharan Africa are discussed.

  2. First record of Corbicula largillierti (Philippi 1844) in the Paraíba River Basin and potential implications from water diversion of the São Francisco River / Primeiro registro de Corbicula largillierti (Philippi 1844) na bacia do Rio Paraíba e implicações potenciais com a transposição das águas do Rio São Francisco

    Scientific Electronic Library Online (English)

    Evaldo de Lira, Azevêdo; José Etham de Lucena, Barbosa; Teofânia H. D. A., Vidigal; Marcos, Callisto; Joseline, Molozzi.

    2014-12-01

    Full Text Available Corbicula largillierti é um molusco nativo da China. No Brasil esta espécie foi registrada primeiramente no Pantanal do Mato Grosso. Esta nota registra a primeira ocorrência de C. largillierti na bacia do Rio Paraíba (semiárido brasileiro). Considera também os riscos potenciais de introdução de outr [...] os moluscos invasores nesta bacia devido è transposição das águas do Rio São Francisco. As densidades do molusco variaram de 33 a 65 ind.m-2 (atingindo valor máximo de 484 ind.m-2) em sedimentos grossos (cascalho, 2-4 mm). A transposição das águas do Rio São Francisco pode ocasionar a introdução de novas espécies exóticas potencializando problemas ecológicos na bacia do Rio Paraíba. Abstract in english Corbicula largillierti is a native mollusk from China. In Brazil, this species was first recorded in the Pantanal of Mato Grosso. This short communication reports the occurrence of C. largillierti for the first time in the Paraíba river basin (Brazilian semi-arid), and also considers the risk of int [...] roduction of other molluscs invaders in this basin due to the diversion of water from the São Francisco River. Densities of individuals ranged from 33 to 65 ind.m-2 (maximum values of 484 ind.m-2) in coarse sediment (gravel, 2-4 mm). The diversion of waters from the São Francisco river can lead to the introduction of new species, enhancing ecological problems in the Paraiba river basin.

  3. Climate Change Impacts on Water Availability and Use in the Limpopo River Basin

    OpenAIRE

    Tingju Zhu; Claudia Ringler

    2012-01-01

    This paper analyzes the effects of climate change on water availability and use in the Limpopo River Basin of Southern Africa, using a linked modeling system consisting of a semi-distributed global hydrological model and the Water Simulation Module (WSM) of the International Model for Policy Analysis of Agricultural Commodities and Trade (IMPACT). Although the WSM simulates all major water use sectors, the focus of this study is to evaluate the implications of climate change on irrigation wat...

  4. BASIN: Beowulf Analysis Symbolic INterface

    Science.gov (United States)

    Vesperini, Enrico; Goldberg, David M.; McMillan, Stephen L. W.; Dura, James; Jones, Douglas

    2013-08-01

    BASIN (Beowulf Analysis Symbolic INterface) is a flexible, integrated suite of tools for multiuser parallel data analysis and visualization that allows researchers to harness the power of Beowulf PC clusters and multi-processor machines without necessarily being experts in parallel programming. It also includes general tools for data distribution and parallel operations on distributed data for developing libraries for specific tasks.

  5. Great Basin paleoenvironmental studies project

    International Nuclear Information System (INIS)

    Project goals, project tasks, progress on tasks, and problems encountered are described and discussed for each of the studies that make up the Great Basin Paleoenvironmental Studies Project for Yucca Mountain. These studies are: Paleobotany, Paleofauna, Geomorphology, and Transportation. Budget summaries are also given for each of the studies and for the overall project

  6. Hydrocarbon accumulations in the Tarim basin, China

    Energy Technology Data Exchange (ETDEWEB)

    Li Desheng [Research Institute of Petroleum Exploration and Development, Beijing (China); Liang Digang; Jia Chengzao; Wang Gang [Tarim Petroleum Exploration and Development Bureau, Korle (China)] [and others

    1996-10-01

    The Tarim basin is the largest and least explored inland basin in China. The areal extent of the basin reaches 560,000 km{sup 2}. The interior of the basin is mostly covered by the Takla Mekan Desert, which is about 330,000 km{sup 2} in areal extent. The basin has become the object of special attention since China set aside first- and third-round onshore bidding blocks in the Tarim basin for foreign oil firms to explore. The Tarim basin is a polyhistory superimposed basin that has experienced seven evolutionary stages: (1) Sinian-Cambrian-Ordovician aulacogen stage, (2) Silurian-Devonian intracratonic depression stage, (3) Carboniferous marginal sea stage, (4) Permian rift basin stage, (5) Triassic-Jurassic foreland basin stage, (6) Cretaceous-Paleogene NeoTethys bay stage, and (7) Neogene-Pleistocene foreland and inland basin stage. Both the basin`s Paleozoic marine platform sequences and the Mesozoic-Cenozoic terrestrial fills are believed to contain substantial volumes of hydrocarbons. After recent years of exploration, nine oil and gas fields have been proven and 23 discoveries have been made in the Tabei, Tazhong, and Southwest areas. Kekeya, Lunnan, Sangtamu, Jiefangqudong, Donghetang, and Tazhong 4 oil fields have been put into production. Output of crude oil was 2.6 million t (metric tons) (52,000 BOPD) in 1995. The production will increase to 5 million t (100,000 BOPD) in 1997. Giant oil and gas traps probably will be discovered in the Tarim basin. The prospect is promising.

  7. Peixes da Estação Ecológica Serra Geral do Tocantins, bacias dos Rios Tocantins e São Francisco, com observações sobre as implicações biogeográficas das "águas emendadas" dos Rios Sapão e Galheiros / Fishes from the Serra Geral do Tocantins Ecological Station, Rio Tocantins and Rio São Francisco basins, with remarks on the biogeographical implications of the common headwater between the Rio Sapão and Rio Galheiros

    Scientific Electronic Library Online (English)

    Flávio César Thadeo de, Lima; Rodrigo Antunes, Caires.

    2011-03-01

    Full Text Available Um levantamento preliminar da ictiofauna que ocorre na Estação Ecológica Serra Geral de Tocantins, situada no Sudeste do Estado do Tocantins e Noroeste do Estado da Bahia, é apresentado. A Estação Ecológica Serra Geral de Tocantins situa-se no divisor de águas entre as bacias do Rio São Francisco (R [...] io Sapão) e Rio Tocantins (bacias dos Rios Novo, Balsas e Manuel Alves). A cabeceira comum ou "água emendada" do Rio Sapão e Rio Galheiros, este um afluente do Rio Novo, situa-se no interior da estação e é considerada na literatura como uma possível área de intercâmbio ictiofaunístico entre a bacia do Rio São Francisco e a bacia do Rio Tocantins. Trinta e cinco espécies de peixes foram registradas dentro da Estação Ecológica Serra Geral de Tocantins e em seu entorno imediato, algumas delas desconhecidas da ciência e possivelmente endêmicas da região. Um total de 111 espécies de peixes foi registrado regionalmente (incluindo espécies de peixes registrados nos trechos do Rio Sapão e do Rio Novo/do Sono abaixo da estação). O acará Cichlasoma sanctifranciscense é aqui registrado pela primeira vez na bacia do Rio Tocantins. A ocorrência desta espécie, bem como do lambari Astyanax novae, no Rio Sapão e no Rio Novo/do Sono, são considerados os únicos exemplos inequívocos de transposição natural de espécies de peixes entre as bacias do Rio São Francisco e Tocantins efetuado pelas águas emendadas dos rios Sapão e Galheiros. Abstract in english A preliminary ichthyofaunistic survey conducted at the Serra Geral de Tocantins Ecological Station (Southeastern Tocantins and Northwest Bahia States, central Brazil) is presented. This Ecological Station is situated at the water divide between the Rio São Francisco basin (Rio Sapão) and Rio Tocanti [...] ns (Rio Novo, Rio Balsas, and Rio Manuel Alves da Natividade basins). A common headwater ("água emendada") between the Rio Sapão and the Rio Galheiros (the latter a tributary of the Rio Novo) lies within the station boundaries and is considered in the literature as a potential area of faunistic interchange between the Rio São Francisco and the Rio Tocantins basins. Thirty-five fish species were recorded within the Serra Geral de Tocantins Ecological Station and at its immediate surroundings, some of which unknown to science and potentially endemic to the area. A total of 111 fish species were regionally recorded (i.e., including fish species recorded at downstream stretches of the Rio Sapão and Rio Novo/do Sono, below the ecological station). The cichlid Cichlasoma sanctifranciscense is here recorded for the first time for the Rio Tocantins basin. The occurrence of this species, as well as of the characin Astyanax novae in both the Rio Sapão and Rio Novo/do Sono basins, are here considered to be the only unequivocal examples of fish species that naturally transposed the water divide between the Rio São Francisco and the Rio Tocantins basins effected by the common headwater between Rio Sapão and Rio Galheiros.

  8. THE ADVANCED CHEMISTRY BASINS PROJECT

    Energy Technology Data Exchange (ETDEWEB)

    William Goddard; Peter Meulbroek; Yongchun Tang; Lawrence Cathles III

    2004-04-05

    In the next decades, oil exploration by majors and independents will increasingly be in remote, inaccessible areas, or in areas where there has been extensive shallow exploration but deeper exploration potential may remain; areas where the collection of data is expensive, difficult, or even impossible, and where the most efficient use of existing data can drive the economics of the target. The ability to read hydrocarbon chemistry in terms of subsurface migration processes by relating it to the evolution of the basin and fluid migration is perhaps the single technological capability that could most improve our ability to explore effectively because it would allow us to use a vast store of existing or easily collected chemical data to determine the major migration pathways in a basin and to determine if there is deep exploration potential. To this end a the DOE funded a joint effort between California Institute of Technology, Cornell University, and GeoGroup Inc. to assemble a representative set of maturity and maturation kinetic models and develop an advanced basin model able to predict the chemistry of hydrocarbons in a basin from this input data. The four year project is now completed and has produced set of public domain maturity indicator and maturation kinetic data set, an oil chemistry and flash calculation tool operable under Excel, and a user friendly, graphically intuitive basin model that uses this data and flash tool, operates on a PC, and simulates hydrocarbon generation and migration and the chemical changes that can occur during migration (such as phase separation and gas washing). The DOE Advanced Chemistry Basin Model includes a number of new methods that represent advances over current technology. The model is built around the concept of handling arbitrarily detailed chemical composition of fluids in a robust finite-element 2-D grid. There are three themes on which the model focuses: chemical kinetic and equilibrium reaction parameters, chemical phase equilibrium, and physical flow through porous media. The chemical kinetic scheme includes thermal indicators including vitrinite, sterane ratios, hopane ratios, and diamonoids; and a user-modifiable reaction network for primary and secondary maturation. Also provided is a database of type-specific kerogen maturation schemes. The phase equilibrium scheme includes modules for primary and secondary migration, multi-phase equilibrium (flash) calculations, and viscosity predictions.

  9. The pulsating earth and the origin of intracratonic structures

    Energy Technology Data Exchange (ETDEWEB)

    Tippet, C.R. [Shell Canada Ltd., Calgary, AB (Canada). Calgary Research Centre

    1997-09-01

    A model has been developed to explain the evolution of intracratonic structures such as the Peace River Arch and the Williston Basin. The implications of this model are significant in that for many years these structures have puzzled stratigraphers and structural geologists. The model proposes slight fluctuations in the volume of the Earth, as distinct from the plate margin processes, to drive the formation of intracratonic structures. According to the model, during episodes of global contraction most cratonic areas sink lower into basins separated by residual ridges or arches. Geometries are influenced by pre-existing heterogeneities in the crust and sediment loading. During episodes of global expansion, basin centres invert and the arches collapse. Repeated contractions and expansions reactivate the same pattern of structural elements.

  10. Evidence of syn tectonic tephrites with nepheline in the Sidi Said Maachou Cambrian basin (coastal Meseta, Morocco); geo dynamic implications; Mise en evidence de tephrites a nepheline syntectoniques dans le bassin cambrien de Sidi Said Maachou (Meseta cotiere, Maroc); signification geodynamique

    Energy Technology Data Exchange (ETDEWEB)

    Remmal, T.; Mohsine, A.; El Hatimi, N.

    2009-07-01

    Based on a combined structural, petrographic, and geochemical analysis, a new interpretation of the basic magmatism of Sidi Said Maachou (coastal Meseta) in two stages of emplacement is proposed. The first stage is characterized by transitional pyroclastic flows that have accompanied the opening of the West-Mesetian basin, during the Cambrian; the second stage is made of dykes of basalts, dolerites, and tephrites bearing nepheline. The emplacement of this undersaturated alkaline magma is associated to a sinistral sub meridian shear zone which has been activated at the end of the Caledonian orogenesis, by a mantellic advection. (Author) 32 refs.

  11. Exploration for unconformity-associated uranium deposits: Learning from EXTECH IV, Athabasca basin multidisciplinary study, Canada

    International Nuclear Information System (INIS)

    Unconformity-associated uranium (U) deposits in the Athabasca Basin (hereafter 'the Basin') are pods, veins and disseminations of uraninite spatially associated with the basal unconformity of relatively flat, 1-2 km, unmetamorphosed but pervasively diagenetically altered, Paleo- to Mesoproterozoic, red siliciclastic strata. This is one of four such basins in the northwestern Canadian Shield that were filled by westerly flowing rivers with local complexities related to growth faults. Basement metamorphic belts are folded and interleaved Archean and Paleoproterozoic granitoid and supracrustal rocks. The intensely paleoweathered unconformity preserves variable thicknesses of red hematitic, clay-altered saprolite grading down through a green chloritic zone to fresh rock. The world's largest known highgrade unconformity-associated U deposits are along the basement Wollaston-Mudjatik transition domain. Cigar Lake and McArthur River deposits contain 131,400 and ?190,000 tonnes U at grades of 15% and 23% U, respectively. Uranium dominates in monometallic (generally basement-hosted) deposits and is the principle commodity in polymetallic deposits with variable amounts of Ni + Co + As and traces of Au, Pt, Cu etc. Elsewhere in the basin, high grades have been mined and excellent prospects are being explored. EXTECH IV was a multidisciplinary field and laboratory project to enhance and preserve geoscience data and improve exploration methods for unconformity-associated U deposits. Regional to detailed research was coordinated at exploration sites across the Basin and focused at McArthur River. This report presents the results by discipline, with implications for exploration. New regional basement geology and revised Athabasca group stratigraphy and geological map were reported. Faults, basin and ore deposits are linked, structurally reworked ore is consistent with multiple ore-forming events, paleo-valleys are spatially associated with some Athabasca ore deposits, new software and improved technology have rejuvenated the geophysical and geochemical exploration toolkit for the basin. Potential sources of organic reductants to precipitate uraninite and sources and transport of uranium were discussed and significant unresolved questions posed

  12. Terrestrial vegetation and aquatic chemistry influence larval mosquito abundance in catch basins, Chicago, USA

    Directory of Open Access Journals (Sweden)

    Gardner Allison M

    2013-01-01

    Full Text Available Abstract Background An important determinant of mosquito-borne pathogen transmission is the spatial distribution of vectors. The primary vectors of West Nile virus (WNV in Illinois are Culex pipiens Linnaeus (Diptera: Culicidae and Culex restuans Theobald. In urban environments, these mosquitoes commonly oviposit in roadside storm water catch basins. However, use of this habitat is inconsistent, with abundance of larvae varying significantly across catch basins at a fine spatial scale. Methods We tested the hypothesis that attributes of the biotic and abiotic environment contribute to spatial and temporal variation in production of mosquito vectors, characterizing the relationship between terrestrial vegetation and aquatic chemistry and Culex abundance in Chicago, Illinois. Larvae were sampled from 60 catch basins from June 14 to October 3, 2009. Density of shrubs and 14 tree genera surrounding the basins were quantified, as well as aquatic chemistry content of each basin. Results We demonstrate that the spatial pattern of Culex abundance in catch basins is strongly influenced by environmental characteristics, resulting in significant variation across the urban landscape. Using regression and machine learning techniques, we described landscape features and microhabitat characteristics of four Chicago neighborhoods and examined the implications of these measures for larval abundance in adjacent catch basins. The important positive predictors of high larval abundance were aquatic ammonia, nitrates, and area of shrubs of height Culex during the fruit-bearing periods and early senescent periods in August and September. Conclusions This study identifies environmental predictors of mosquito production in urban environments. Because an abundance of adult Culex is integral to efficient WNV transmission and mosquitoes are found in especially high densities near larval habitats, identifying aquatic sites for Culex and landscape features that promote larval production are important in predicting the spatial pattern of cases of human and veterinary illness. Thus, these data enable accurate assessment of regions at risk for exposure to WNV and aid in the prevention of vector-borne disease transmission.

  13. The Central European Permian Basins; Rheological and structural controls on basin history and on inter-basin connectivity

    Science.gov (United States)

    Smit, Jeroen; Van Wees, Jan-Diederik; Cloetingh, Sierd

    2014-05-01

    We analyse the relative importance of the major crustal-scale fault zones and crustal architecture in controlling basin formation, deformation and the structural connections between basins. The North and South Permian Basins of Central Europe are usually defined by the extend of Rotliegend sedimentary and volcanic units and not by a common tectonic origin or development. Instead, the sub-basins that together form the Permian Basins are each controlled by different structural and/or rheological controls that are inherited from Early Paleozoïc and older geodynamic processes, they are even located in different crustal/lithospheric domains. The North Permian basin is located on Baltic crust that was thinned during Late Proterozoïc - Early Paleozoïc times. South of the Thor suture, the South Permian basin and its sub-basins are located on Avalonian crust (Southern North Sea and North German Basins) and on the transition of East European cratonic and Avalonian crust (Polish Through). The size of crustal domains and of the faults that govern basin formation requires a regional-scale to assess their impact on basins and sub-basins. In the case of the Permian Basins this encompasses East Avalonia and surroundings, roughly speaking the area north of the Variscan Rheïc suture, east of the Atlantic and southwest of the Teisseyre-Tornquist line. This approach sheds light on the effects of long lived differences in crustal fabric which are responsible for spatial heterogeneity in stress and strain magnitudes and zonations of fracturing, burial history and temperature history. The focus on understanding the geomechanical control of large crustal-scale fault structures will provide the constraints and geometrical and compositional input for local models of stress and strain. Considering their fundamentally different structural and rheological controls, the Permian (sub)basins have a remarkably common history of subsidence and inversion, suggesting a more or less continuous link between them. Post-Variscan, Late Carboniferous-Early Permian wrench tectonics is the oldest and main identified cause for regional basin formation in Central Europe. This relatively short-lived tectonic regime cannot explain the observed common history of subsidence of the Permian Basins during the 200 My that followed. Our analysis demonstrates that transfer faults that both follow and cross rheological transitions and inherited fault zones continued to be active after the early Permian. We therefore suggests that crustal-scale transfer faults may be the missing link that explains the common subsidence history of basins with a fundamentally different crustal architecture and structural history.

  14. The sedimentary basins of Tanzania - reviewed

    Science.gov (United States)

    Mbede, E. I.

    The sedimentary basins of Tanzania have been classified into four morphotectonic groups: the coastal basin, the Karoo rift basins, basins found within the present East African rift valley and the cratonic sag basins. Except for the cratonic sag basins, each of these basin group has been affected by rifting at one time or another. The geology of each basin is discussed, structural evolution is evaluated and the prospectivity is thence looked into. Coal is exploited at Songwe-Kiwira coalfield and is found in potentially economic quantities in other Karoo basins. Prospecting for hydrocarbon resources has been going on since the 50s. Gas has been discovered in Songosongo and Mnazi bay fields, uneconomical quantities of oil have also been reported in Songosongo. Being basically rift basins which have reached different stages of development, source rocks normally associated with Initial-rifting, synrifting as well as post-rifting processes are probably well developed. Reservoir rocks, traps and cap rocks are normally not rare in such tectonic environments. Thermal gradients associated with the rifting stage are normaly high to effect maturation of source rocks even at low sedimentary thicknesses. Studies done so far are still inconclusive, because while testing has mainly been focused on structural traps stratigraphic traps seems to be more promising.

  15. Tools for river basin management

    OpenAIRE

    Cools, Jan

    2012-01-01

    Water resources management can be challenging when confronted with pollution, water shortage, floods, water-related diseases, climate change and variability. In this thesis, it is assessed how the management of a multi-functional river basin can be facilitated through the development and testing of analytical tools in data-poor and data-rich context. A variety of tools and strategies is developed and tested on a variety of stakeholder selected themes, namely: •Cost-effective improvement of wa...

  16. UPPER SNAKE RIVER PRIORITY BASIN ACCOMPLISHMENT PLAN, APRIL 1973

    Science.gov (United States)

    The Upper Snake Accomplishment Basin (17040104, 170402, 170501) is defined as the Idaho and Oregon portions of 2 STORET Basins, the Upper Snake Basin and the Central Snake Basin. The Basin drains approximately 62,100 square miles in Southern Idaho and Southeastern Oregon. Four ...

  17. Drainage basin delineations for selected USGS streamflow-gaging stations in Virginia (Drainage_Basin)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Drainage_Basin polygon feature class was created as a digital representation of drainage basins for more than 1,650 continuous-record streamflow-gaging...

  18. Basins of Attraction for Chimera States

    OpenAIRE

    Martens, Erik A.; Panaggio, Mark J; Abrams, Daniel M.

    2015-01-01

    Chimera states---curious symmetry-broken states in systems of identical coupled oscillators---occur only for special initial conditions. Here we analyze their basins of attraction in a simple system comprised of two populations. Using perturbative analysis and numerical simulation we evaluate asymptotic states and associated destination maps, and demonstrate that basins form a complex twisting structure in phase space. Understanding the basins' precise nature may help in dev...

  19. Reserves in western basins: Part 1, Greater Green River basin

    Energy Technology Data Exchange (ETDEWEB)

    1993-10-01

    This study characterizes an extremely large gas resource located in low permeability, overpressured sandstone reservoirs located below 8,000 feet drill depth in the Greater Green River basin, Wyoming. Total in place resource is estimated at 1,968 Tcf. Via application of geologic, engineering and economic criteria, the portion of this resource potentially recoverable as reserves is estimated. Those volumes estimated include probable, possible and potential categories and total 33 Tcf as a mean estimate of recoverable gas for all plays considered in the basin. Five plays (formations) were included in this study and each was separately analyzed in terms of its overpressured, tight gas resource, established productive characteristics and future reserves potential based on a constant $2/Mcf wellhead gas price scenario. A scheme has been developed to break the overall resource estimate down into components that can be considered as differing technical and economic challenges that must be overcome in order to exploit such resources: in other words, to convert those resources to economically recoverable reserves. Total recoverable reserves estimates of 33 Tcf do not include the existing production from overpressured tight reservoirs in the basin. These have estimated ultimate recovery of approximately 1.6 Tcf, or a per well average recovery of 2.3 Bcf. Due to the fact that considerable pay thicknesses can be present, wells can be economic despite limited drainage areas. It is typical for significant bypassed gas to be present at inter-well locations because drainage areas are commonly less than regulatory well spacing requirements.

  20. Late Pleistocene Paleohydrology of Willcox Basin, Southeastern Basin and Range from 14C-Chronostratigraphy, Sedimentology, Fauna, and Stable Isotopes of Wetland and Lake-Shoreline Deposits

    Science.gov (United States)

    Kowler, A.; Bright, J. E.; Quade, J.

    2014-12-01

    Fossil shorelines record the areal extent of past lake expansions in closed basins of arid regions worldwide, reflecting hydrologic balance changes from one lake cycle to the next. Paleo-lake records from the northern Great Basin indicate low to intermediate lake levels there during the last glacial maximum (LGM: ca. 23-19 Cal ka BP) relative to those reached during the subsequent Deglacial interval, particularly in response to Heinrich events and attendant collapse of the Atlantic Meridional Overturning Circulation (AMOC) during the Heinrich 1 (H1) stadial (ca. 17.5-14.6 Cal ka BP). Competing hypotheses about the causes of these cycles imply that southern Basin and Range paleo-lakes experienced lake-level maxima during the LGM, rendering shoreline chronologies from that region of paramount importance to understanding regional atmospheric dynamics during this critical climate transition. In southeastern Arizona, highstands of paleo-Lake Cochise overlapped with many highstands in the Great Basin, forming a composite beach ridge in Willcox Basin from ca. 17 to ca. 13 Cal ka BP. However, recent 14C dating of shells and carbonates within a calcareous mudstone unit (Unit 5) buried beneath the ridge constrain emplacement of Unit 5 to ca. 19 Cal ka BP; evidence from the faunal and stable isotopic composition of ostracode and gastropod assemblages reveals the mudstone's lacustrine origin. Given that similar mudstones in drained basins of the southern Great Basin are known to have formed in paleo-wetlands, our findings have large implications for detecting and constraining the timing of ancient lake cycles and wetland expansions in arid closed basins worldwide. With respect to paleoclimate, the Unit 5 lake cycle occurred in advance of H1 and formation of the beach ridge by ~2 millennia, whereas the beach ridge continued to form following the H1 stadial. This suggests that lake cycles associated with the terminal LGM, H1 stadial, Bolling-Allerod, and Younger Dryas climatic intervals occurred in response to different triggers, themselves effecting major changes in AMOC circulation and/or sea-surface temperatures in the North Atlantic.

  1. 78 FR 65609 - Medicine Bow-Routt National Forests and Thunder Basin National Grassland; Wyoming; Thunder Basin...

    Science.gov (United States)

    2013-11-01

    ...Basin National Grassland Prairie Dog Amendment EIS. The EIS will...Basin National Grassland Prairie Dog Amendment. The Open House...Wyoming--Laramie County Library-- Sunflower Room--2200 Pioneer...Basin National Grassland Prairie Dog Amendment will be available...

  2. 78 FR 56650 - Medicine Bow-Routt National Forests and Thunder Basin National Grassland; Wyoming; Thunder Basin...

    Science.gov (United States)

    2013-09-13

    ...Basin National Grassland Prairie Dog Amendment AGENCY: Forest Service...Basin National Grassland Prairie Dog Amendment. The Open House...Wyoming--Laramie County Library-- 2200 Pioneer Ave. The meetings...Basin National Grassland Prairie Dog Amendment will be available...

  3. Delaware Basin Monitoring Annual Report

    International Nuclear Information System (INIS)

    The Delaware Basin Drilling Surveillance Program (DBDSP) is designed to monitor drilling activities in the vicinity of the Waste Isolation Pilot Plant (WIPP). This program is based on Environmental Protection Agency (EPA) requirements. EPA requires the Department of Energy (DOE) to demonstrate the expected performance of the disposal system using a probabilistic risk assessment or performance assessment (PA). This PA must show that the expected repository performance will not release radioactive material above limits set by the EPA's standard and must consider inadvertent drilling into the repository at some future time.

  4. Groundwater recharge environments and hydrogeochemical evolution in the Jiuquan Basin, Northwest China

    International Nuclear Information System (INIS)

    The groundwater recharge environments and hydrogeochemical characteristics in the Quaternary aquifer of Jiuquan Basin was investigated using a combination of chemical indicators, stable isotopes, and radiocarbon dating. The d-excess values of winter precipitation and surface water revealed that the meltwater from snow and ice played the dominant role in the basin’s surface water supply. The unconfined groundwater showed gradual enrichment of heavy isotopes along the flow path, but ?18O and ?2H values were similar to those of surface water, suggesting recent recharge as a result of rapid seepage along rivers combined with the effects of high evaporation. The 14C (pmc) values of unconfined groundwater was between 71.5% and 90.9%, and since 80% modern carbon probably represents the upper limit of initial 14C activity, this suggests that the groundwater is relatively young. The confined groundwater was depleted in heavy isotopes; coupled with low 14C values (?20–53%), indicating that the groundwater was mainly recharged as palaeowater during the late Pleistocene and Holocene epochs under a cold climate. The surface water and most groundwater samples were fresh rather than saline, with TDS ?1, respectively. The chemistry of unconfined groundwater changed from HCO3-dominated to no dominant ions and then to SO42-dominated moving along the flow path from the Jiuquan-Jiayuguan Basin to the Jinta Basin, and the confined water was SO42-dominated. The results have important implications for groundwater management in the Basin, where a high proportion of the water being used is in effect being mined (i.e., extracted faster than its replacement rate); thus, significant changes are urgently needed in the regional water-use strategy.

  5. Red River Basin Mapping 2008-2010

    Data.gov (United States)

    Federal Emergency Management Agency, Department of Homeland Security — This LiDAR data covers the Red River Basin with portions of ND, MN, SD and flows into Canada. The US Red River Basin boudnary covers 40,860 sqmi,with the additional...

  6. The karst hydrogeology of upper Ermenek Basin

    International Nuclear Information System (INIS)

    The karst hydrogeology of the Upper Ermenek Basin whose surface area is about 2050 km2 is investigated within the framework of this study. The investigation comprised mainly the study of the characteristics of karstification in the basin and the role of the karstic features on the regional hydrodynamic structure. regional hydrodynamic structure

  7. K-Basin isolation barrier seal

    International Nuclear Information System (INIS)

    This report documents various aspects of the design, analysis, procurement, and fabrication of the hydraulic seal on the isolation barriers to be installed in the 100-K Area spent nuclear fuel basin. The isolation barrier is used to keep water in the basin in the event of an earthquake

  8. A Mantle Cause for Congo Basin Subsidence?

    Science.gov (United States)

    Buiter, S.; Steinberger, B. M.; Medvedev, S.; Tetreault, J. L.

    2011-12-01

    The Congo Basin in Central Africa is often cited as an example of an intracratonic basin due to its near-circular shape, pronounced negative free-air gravity anomaly, and long subsidence history. The basin probably initiated by late Precambrian rifting of thick cratonic lithosphere and a large part of its subsidence history could be explained by post-rift thermal relaxation. However, the upper 1 km of Mesozoic to Cenozoic sediments seems discontinuous in its evolution and several studies have proposed that these sediments were deposited in response to mantle processes. Several hypotheses have been put forward to explain the latest subsidence phase of the Congo Basin: a) a high-density body within the deeper lithosphere, b) downward mantle flow beneath the basin driven by small plumes rising up below the basin flanks, c) a relatively recent response at about 30 Ma to uplifts surrounding the basin formed by shallow mantle convection, d) downward mantle flow above a detached lithospheric fragment that sinks into the mantle, and e) continued post-rift subsidence. These hypotheses inspired us to examine gravity data and 18 seismic tomography models to evaluate the role of the sub-crustal mantle in the more recent evolution phase of the Congo Basin. Using upper mantle tomography and lithosphere thickness models, we show that the Congo Basin is underlain by thick lithosphere and that the basin boundaries may coincide with the Congo Craton boundaries. Hypotheses that link uplift at craton boundaries to basin evolution are therefore possible within these data. Reducing the free-air gravity field by corrections for topography and sediments results in slightly negative to positive residual anomalies, depending on the density assumed for the sediments. Because of the lower density of the basin sediments, isostatic compensation by a dense body in the subcrustal mantle or a dynamic mantle component is required. Thirteen whole-mantle and five upper-mantle tomography models do, however, not yield a consistent picture of the mantle beneath the Congo lithosphere and the large inter-model variability precludes inferences of a mantle mechanism for recent Congo Basin subsidence. We speculate that deposition of the Mesozoic-Cenozoic sediments could have raised the surface elevation of the Congo Basin to the present average level of about 400 m above sea-level and that the last subsidence phase is merely a consequence of the sediment load instead of the cause.

  9. China, JNOC start exploration in Tarim basin

    International Nuclear Information System (INIS)

    This paper reports that a joint venture of China National Oil and Natural Gas Corp and Japan National Oil Corp (JNOC) has begun exploration in Northwest China's remote Tarim basin in Xinjiang Uygur Autonomous Region. That marks the first time China has allowed a foreign oil company to participate in exploration of the highly prospective basin. China pins much of its hope for the future on the Tarim basin as production declines from its older, mainstay fields in the east and offshore results have proved largely disappointing. The Chinese-Japanese combine began operations in the southwest part of the 560,000 sq km basin. The 200 member exploration team plans to complete a seismic survey covering 3,500 line km in the Kashi and Yecheng areas during the next 4 1/2 years. The survey follows a feasibility study that began last October covering 30,000 sq km in the basin

  10. Petroleum geochemistry of the Zala Basin, Hungary

    Science.gov (United States)

    Clayton, J.L.; Koncz, I.

    1994-01-01

    The Zala basin is a subbasin within the Pannonian basin. Geochemical study of oils and rocks in the basin indicate that two, and possibly three, genetic oil types are present in the basin. Miocene source rocks, previously believed to be the predominant source rock, have expelled minor amounts of hydrocarbons. The main source rock is the Upper Triassic (Rhaetian) Kossen Marl Formation or its stratigraphic equivalent. Knowledge of the geochemical characteristics of oils derived from these Upper Triassic source rocks and understanding of the source rock distribution and maturation history are important for recognizing Triassic oil-source bed relationships and for further exploration in other basins in Hungary and other parts of Europe where Triassic source rocks are present. -from Authors

  11. 105-KE basin pilot run relocation

    International Nuclear Information System (INIS)

    The purpose of this document is to present the bases for selecting the exact in-facility location for installation of process equipment to support pilot testing activities in the 105-KE Basin at the United States Department of Energy Hanford Site, in southeastern Washington State. The 105-KE Basin was constructed during the early 1950s, as an integralcomponent of the 105-K East reactor building. Similar basins were provided in all Hanford weapons production reactor buildings to receive fuel elements discharged from the reactors and stage them for rail transport to 200 Area fuel reprocessing plants. The 105-KE reactor began operation in 1955. It was shut down in 1971. However, the 105-KE Basin was reactivated several years later to store spent fuel from the N-Reactor basin and permit its continued operation during outages at the Plutonium Uranium Extraction (PUREX) plant in the 200E Area

  12. Implementing Integrated River Basin Management in China

    Directory of Open Access Journals (Sweden)

    Lifeng Li

    2010-06-01

    Full Text Available This paper examines the role of the World Wildlife Fund for Nature China as policy entrepreneur in China. It illustrates the ways in which the World Wildlife Fund for Nature is active in promoting integrated river basin management in the Yangtze River basin and how the efforts at basin level are matched with the advice of the China Council for International Cooperation on Environment and Development task force on integrated river basin management to the national government of China. This article demonstrates that the World Wildlife Fund for Nature uses various strategies of different types to support a transition process towards integrated river basin management. Successful deployment of these strategies for change in environmental policy requires special skills, actions, and attitudes on the part of the policy entrepreneur, especially in China, where the government has a dominant role regarding water management and the position of policy entrepeneurs is delicate.

  13. Geochemistry of late Quaternary tephra-sediment sequence from north-eastern Basin of Mexico (Mexico): implications to tephrochronology, chemical weathering and provenance / Geoquímica de una secuencia tefrosedimentaria del Cuaternario Tardío del noreste de la cuenca de México (México): Implicaciones para la tefrocronología, intemperismo químico y proveniencia

    Scientific Electronic Library Online (English)

    Priyadarsi D., Roy; José Luis, Arce; Rufino, Lozano; M.P., Jonathan; Elena, Centeno; Socorro, Lozano.

    2012-04-01

    Full Text Available En el presente trabajo se estudia la estratigrafía y geoquímica de multielementos de una secuencia tefro-sedimentaria localizada al noreste de la Cuenca de México (subcuenca de Pachuca, centro de México), con el fin de entender la tefrocronología, proveniencia y condiciones de intemperismo químico d [...] urante el Cuaternario Tardío. Se compara la composición química de las tefras con productos de estructuras volcánicas de los alrededores del área de estudio (Apan-Tezontepec, Acoculco, Huichapan, Sierra de las Cruces y Tláloc) con el fin de identificar su posible fuente. Las tefras de composición basáltica a andesita-basáltica (Tr 1, Tr 6 y Tr 7) muestran composiciones similares a las rocas del campo monogenético Apan-Tezontepec, con edades entre 1.50 y 0.47 Ma. Las tefras félsicas muestran composiciones químicas similares a las secuencias volcánicas de Acoculco. En particular, la ceniza dacítica (Tr 2), así como los depósitos de caída de pómez riolítica (Tr 3, Tr 4, Tr 5 y Tr 8) podrían representar diferentes erupciones de tipo pliniano de la caldera Acoculco, ocurridas entre 0.24 Ma. Diagramas ternarios (A-CN-K, A-C-N y A-CNK-FM) y la concentración de elementos traza sugieren que algunos de los sedimentos intercalados son productos de alteración de las tefras y los restos de sedimentos en la secuencia provienen de la erosión de rocas que afloran en la sierra volcánica de Pachuca. Los índices de intemperismo químico como CIA y PIA indican variaciones en el grado de alteración química para estos sedimentos, posiblemente relacionado a fluctuaciones de la humedad y tiempo de su transporte desde el interior a la subcuenca. Abstract in english A ca.30 m thick tephra-sediment sequence from the north-eastern Basin of Mexico (Pachuca sub-basin, central Mexico) is investigated for stratigraphy and multi-element geochemistry to understand the tephrochronology, provenance and conditions of chemical weathering duringLate Quaternary. Chemical com [...] positions of tephra layers are compared with products from surrounding volcanic structures (Apan-Tezontepece, Acoculco, Huichapan, Sierra de las Cruces and Tláloc) in order to identify their sources. Basalt to basaltic-andesite tephra layers (Tr 1, Tr 6 and Tr 7) show similar composition with rocks from Apan-Tezontepec monogenetic volcanicfield aged between 1.50 and 0.47Ma. Felsic tephra layers have composition comparable to Acoculco volcanic sequence. The dacitic ash (Tr 2) and rhyolitic ash and pumice fall deposits (Tr 3, Tr 4, Tr 5 and Tr 8) might be representatives of different Plinian eruptive events at Acoculco caldera and possibly occurred during 0.24 Ma. Ternary diagrams (A-CN-K, A-C-N and A-CNK-FM) and trace element concentrations suggest that some of the sediment layers are formed from the chemical weathering of the underlying tephra and the rest of the inter-bedded sediments are derived from the erosion of rocks exposed at the Pachuca volcanic range. Indices of chemical weathering such as CIA and PIA indicate varying degrees of chemical alteration for these sediments possibly related to fluctuating humidity and duration of exposure to different weathering agents during their transportation from the hinterland to the sub-basin.

  14. Plio-Pleistocene drainage development in an inverted sedimentary basin: Vera basin, Betic Cordillera, SE Spain

    Science.gov (United States)

    Stokes, Martin

    2008-08-01

    The Vera basin is one of a series of interconnected Neogene-Quaternary sedimentary basins located within the Internal Zone of the Betic Cordillera (southeast Spain). Since the Pliocene the Vera basin has been subjected to low uplift rates (11-21 m Ma - 1 ) and inverted via compressive tectonics that are related to the ongoing oblique collision between the African and Iberian plates. Within this paper the sedimentary and geomorphic response to basin inversion is explored. Sedimentary processes and environments are established for key stratigraphic units of the Pliocene/Plio-Pleistocene basin fill and Pleistocene dissectional landscape. These data are subsequently utilised to reconstruct an evolving basin palaeogeography. Fault and uplift data are employed to discuss the role of tectonically driven basin inversion for controlling the resultant palaeogeographic changes and associated patterns of drainage development. During the Early-Mid Pliocene the Vera basin was characterised by shallow marine shelf conditions (Cuevas Formation). A major palaeogeographic reorganisation occurred during the Mid-Late Pliocene. Strike-slip movement along the eastern basin margin, coupled with uplift and basin emergence created a protected, partially enclosed marine embayment that was conducive for Gilbert-type fan-delta sedimentation from fluvial inputs along the northern and eastern basin margins (Espíritu Santo Formation). The Vera basin then became fully continental and internally drained through the development of a consequent drainage network that formed following the withdrawal of marine conditions during the Late Pliocene to Early Pleistocene. Alluvial fans developed along the northern and western basin margins, grading to a bajada and terminating in a playa lake in central basin areas (Salmerón Formation). During the Early-Mid Pleistocene a switch from basin infilling to dissection took place, recorded by alluvial fan incision, a switch to braided river sedimentation and fluvial incision into the underlying basin fill sediments and basin margin mountainous topography. Fluvial incision, headwards erosion, expansion and modification of the consequent drainage network is documented within a series of up to four major inset river terrace levels and associated landforms. Fluvial incision and drainage network expansion are attributed to differential uplift and the creation of regional gradients between adjacent basins. The relatively low Plio-Pleistocene uplift rate of the Vera basin (11-21 m Ma - 1 ) in comparison to adjacent basins (Sorbas: 80-160 m Ma - 1 ; Huercal-Overa: > 50 m Ma - 1 ) resulted in a switch from internal to external basin drainage. Ancestral forms of the principal drainage systems within the Vera basin: the Ríos Almanzora, Aguas and Antas, captured basins and mountain catchment areas to the north (Huercal-Overa basin), southwest (Sorbas basin) and west (Sierra de los Filabres range). The switch from basin infilling to fluvial dissection is coincident with a phase of Early-Mid Pleistocene compressional tectonics, expressed by extensional faulting. This deformation is probably linked to accelerated strike-slip movement along the Palomares Fault Zone. The faulting is superimposed onto the longer term pattern of Plio-Pleistocene uplift and basin inversion.

  15. Surface-water-quality assessment of the Yakima River Basin in Washington: Overview of major findings, 1987-91

    Science.gov (United States)

    Morace, Jennifer L.; Fuhrer, Gregory J.; Rinella, Joseph F.; McKenzie, Stuart W.; Gannett, Marshall W.; Bramblett, Karen L.; Pogue, Ted R., Jr.; Skach, Kenneth A.; Embrey, Sandra S.; Cuffney, Thomas F.; Meador, Michael R.; Porter, Stephen D.; Gurtz, Martin E.

    1999-01-01

    Surface-water-quality conditions were assessed in the Yakima River Basin, which drains 6,155 square miles of mostly forested, range, and agricultural land in Washington. The Yakima River Basin is one of the most intensively farmed and irrigated areas in the United States, and is often referred to as the “Nation’s Fruitbowl.” Natural and anthropogenic sources of contaminants and flow regulation control water-quality conditions throughout the basin. This report summarizes the spatial and temporal distribution, sources, and implications of the dissolved oxygen, water temperature, pH, suspended sediment, nutrient, organic compound (pesticide), trace element, fecal indicator bacteria, radionuclide, and aquatic ecology data collected during the 1987–91 water years.

  16. Identification of larvicide-resistant catch basins from three years of larvicide trials in a suburb of chicago, IL.

    Science.gov (United States)

    Harbison, Justin E; Sinacore, James M; Henry, Marlon; Xamplas, Christopher; Dugas, Lara R; Ruiz, Marilyn O'Hara

    2014-01-01

    The tens of thousands of catch basins found in many urban areas are a primary target of local vector control agencies for seasonal application of extended-release larvicides. A concern with using larvicides in these structures is that active ingredients can be hampered by high flows, debris, and sediment, all of which are common to these structures. As such a certain proportion of basins may be "resistant" to larvicide treatments due to site specific characteristics that may promote these and other factors that hinder larvicide action and/or promote mosquito infestation. Analyses from three years of larvicide efficacy trials suggest that over a quarter of basins in the study area may not be receiving adequate protection from a single dose of larvicide that is routinely applied. Implications of increasing the dose and/or toxicity of larvicide treatments are discussed further. PMID:25392699

  17. A review of techniques for the estimation of magnitude and timing of exhumation in offshore basins

    Science.gov (United States)

    Corcoran, D. V.; Doré, A. G.

    2005-10-01

    Exhumation, the removal of overburden resulting from the vertical displacement of rocks from maximum burial depth, occurs at both regional and local scales in offshore sedimentary basins and has important implications for the prospectivity of petroliferous basins. In these basins, issues to be addressed by the petroleum geologist include, the timing of thermal 'switch-off' of source rock units, the compactional and diagenetic constraints imposed by the maximum burial depth of reservoirs (prior to uplift), the physical and mechanical characteristics of cap-rocks during and post-exhumation, the structural evolution of traps and the hydrocarbon emplacement history. Central to addressing these issues is the geoscientist's ability to identify exhumation events, estimate their magnitude and deduce their timing. A variety of individual techniques is available to assess the exhumation of sedimentary successions, but generic categorisation indicates that 'point' measurements of rock displacement, in the offshore arena, are made with respect to four frames of reference — tectonic, thermal, compactional or stratigraphic. These techniques are critically reviewed in the context of some of the exhumed offshore sedimentary basins peripheral to the Irish landmass. This review confirms that large uncertainty is associated with estimates from individual techniques but that the integration of seismic interpretation and regional stratigraphic data provides valuable constraints on estimates from the more indirect tectonic, thermal and compactional methods.

  18. Youngest dinocephalian fossils extend the Tapinocephalus Zone, Karoo Basin, South Africa

    Scientific Electronic Library Online (English)

    Michael O., Day; Saniye, Güven; Fernando, Abdala; Sifelani, Jirah; Bruce, Rubidge; John, Almond.

    2015-04-01

    Full Text Available The dinocephalians (Synapsida, Therapsida) were one of the dominant tetrapod groups of the Middle Permian (Guadalupian Epoch, ~270-260 million years ago) and are most abundantly recorded in the Tapinocephalus Assemblage Zone (AZ) of the Main Karoo Basin, South Africa. Dinocephalians are thought to h [...] ave become extinct near the top of the Abrahamskraal Formation of the Beaufort Group and their disappearance is one criterion used to define the base of the overlying Pristerognathus AZ. Because of the abundance of fossils in the Karoo, the Beaufort Group biozones form the biostratigraphic standard for later Permian terrestrial tetrapod ecosystems, so their stratigraphic delineation is of great importance to Permian palaeobiology. We report two new specimens of the rare tapinocephalid dinocephalian Criocephalosaurus from the lowermost Poortjie Member, which makes them the youngest dinocephalians known from the Main Karoo Basin and extends the Tapinocephalus AZ from the Abrahamskraal Formation up into the Teekloof Formation. The extension of the Tapinocephalus AZ relative to the lithostratigraphy potentially affects the biozone or biozones to which a fossil species can be attributed; this extension has implications for biostratigraphic correlations within the Main Karoo Basin as well as with other basins across Gondwana. These discoveries also indicate that a population of herbivorous tapinocephalids survived as rare constituents of the tetrapod fauna after most generic richness within the clade had already been lost.

  19. IMPLICACIONES PALEOAMBIENTALES DE LA PRESENCIA DEL GÉNERO CERATOPHRYS (ANURA, CERATOPHRYINAE) EN CONTEXTOS ARQUEOLÓGICOS DE LA TRANSICIÓN PAMPEANO-PATAGÓNICA EN EL HOLOCENO TARDÍO (CURSO INFERIOR DEL RÍO COLORADO, ARGENTINA) / PALEOEVIRONMENTAL IMPLICATIONS OF THE CERATOPHRYS GENUS (ANURA, CERATOPHRYINAE) FROM ARCHAEOLOGICAL CONTEXTS OF THE PAMPEAN-PATAGONIAN TRANSITION DURING THE LATE HOLOCENE (LOWER BASIN OF THE COLORADO RIVER, ARGENTINA)

    Scientific Electronic Library Online (English)

    LUCIANA, STOESSEL; SERGIO, BOGAN; GUSTAVO, MARTÍNEZ; FEDERICO L, AGNOLIN.

    2008-11-01

    Full Text Available En el presente trabajo se reporta la presencia del género Ceratophrys en la localidad arqueológica San Antonio y en el sitio Paso Alsina 1, ubicados en el curso inferior del río Colorado (provincia de Buenos Aires, Argentina). Los materiales comunicados aquí son asignados al Holoceno Tardío final y [...] representan el registro más meridional conocido para el género, encontrándose en un área de transición Pampeano-Patagónica, a más de 400 kilómetros hacia el sur de su distribución actual. Se mencionan y discuten todas las localidades holocénicas portadoras de elementos óseos referibles a Ceratophrys. La variación corológica de esta especie aquí informada es coincidente con hipótesis paleoambientales que proponen mayores índices de temperatura y posiblemente una mayor disponibilidad hídrica para el Holoceno tardío. Abstract in english In this work, we report the presence of the Ceratophrys genus at the archaeological locality of San Antonio and at the Paso Alsina 1 archaeological site, situated at the lower basin of the Colorado river (Buenos Aires province, Argentina). The materials communicated here are assigned to the late Hol [...] ocene and represent the southernmost evidence known for the genus at the Pampean-Patagonian transition, recorded more than 400 kilometers south of their present-day distribution. Additionally, we mention and discuss all the holocene localities where osseous elements referable to Ceratophrys were found. The corological variation proposed here for the genus Ceratophrys is coincident with paleoenvi-ronmental hypotheses that propose higher temperature and a possible elevated hydric availability rates for the late Holocene.

  20. Sandbox experiments on basin inversion: testing the influence of basin orientation and basin fill

    Science.gov (United States)

    Panien, Marion; Schreurs, Guido; Pfiffner, Adrian

    2005-03-01

    Analogue modelling experiments using brittle materials are performed to study the inversion of extensional structures. Asymmetric grabens of two different orientations are first created during a phase of extension and progressively filled. They are subsequently shortened in the same direction. The aim of our experiments is to determine factors affecting the style of deformation during inversion. We specifically investigate variations in thickness and distribution of strong and weak layers constituting the graben fill and in initial basin orientation. The main advantage of our experimental set-up is that we have a complete control on graben location, width, infill and orientation before inversion. The experiments show that shortening results only in limited reactivation of pre-existing normal faults. In general, forward thrusts and backthrusts cut across normal faults into the footwall of the graben. The forward thrusts either propagate parallel to the enveloping surface of faulted blocks or they cut across basin-limiting normal faults at various angles. The graben fill is mechanically extruded by displacement along forward thrusts that accommodate most of the shortening. Both pre-existing faults and weak graben fill act as zones of weakness during inversion and determine the orientation and location of both backthrusts and forward thrusts. The results of our experiments conform well to natural examples of inverted graben structures.

  1. Weather Variability Affects Abundance of Larval Culex (Diptera: Culicidae) in Storm Water Catch Basins in Suburban Chicago

    OpenAIRE

    Gardner, Allison M; HAMER, GABRIEL L.; HINES, ALICIA M.; NEWMAN, CHRISTINA M.; Walker, Edward D; Ruiz, Marilyn O.

    2012-01-01

    Culex pipiens L. (Diptera: Culicidae) and Culex restuans Theobald are the primary enzootic and bridge vectors of West Nile virus in the eastern United States north of 36° latitude. Recent studies of the natural history of these species have implicated catch basins and underground storm drain systems as important larval development sites in urban and suburban locales. Although the presence of larvae in these habitats is well-documented, the influence of abiotic factors on the ecology of Culex ...

  2. Win-wins in NTFP market chains? How governance impacts the sustainability of livelihoods based on Congo Basin forest products

    OpenAIRE

    Ingram, V.J.

    2014-01-01

    Exploring the interrelationships between governance, poverty alleviation and sustainability impacts in the framework of market chains for non-timber forest products originating from the Congo Basin. The research focuses on how governance arrangements help or hinder access to forest resources and their exploitation, and the implications for poverty alleviation and sustainable livelihoods. The value chains of nine NTFPs are investigated: (Apiculture products: honey, wax and propolis), pygeum ( ...

  3. Prediction of extreme floods based on CMIP5 climate models: a case study in the Beijiang River basin, South China

    OpenAIRE

    Wu, C. H.; G. R. Huang; Yu, H. J.

    2014-01-01

    The occurrence of climate warming is unequivocal, and is expected to be experienced through increases in the magnitude and frequency of extreme events, including flooding. This paper presents an analysis of the implications of climate change on the future flood hazard in the Beijiang River basin in South China, using a Variable Infiltration Capacity (VIC) model. Uncertainty is considered by employing five Global Climate Models (GCMs), three emission scenarios (RCP2.6, RCP4.5...

  4. The surface-piercing salt domes in the Ghaba Salt Basin (Oman): A comparison to the intra-salt hydrocarbon play of the Ara Group

    Science.gov (United States)

    Reuning, L.; Schoenherr, J.; Heimann, A.; Urai, J. L.; Littke, R.; Kukla, P. A.; Rawahi, Z.

    2009-04-01

    In the South Oman Salt Basin the Ara carbonates form an extensively cored, deeply buried intra-salt hydrocarbon play. Six surface-piercing salt domes in the Ghaba Salt Basin (North Oman) provide the only outcrop equivalents for carbonates and evaporites of the Ediacaran-Early Cambrian Ara Group (uppermost Huqf Supergroup). Based on fieldwork, satellite imaging and isotope analysis it is concluded that most of the carbonate bodies (so-called stringers) in the Ghaba salt domes are time equivalent to the stratigraphically uppermost stringer intervals in the South Oman Salt Basin (A5-A6). Maturity analyses demonstrate that the carbonate stringers in the salt domes were transported with the rising Ara salt from burial depths of ~ 6 to 10 km to the surface. Petrographic and stable isotope data show that their diagenetic evolution during shallow and deep burial was very similar to the Ara carbonate stringer play in the SOSB. However, during the retrograde pathway of salt diapir evolution, the carbonate stringers were exposed to strong deformation in the diapir stem and diagenetic alterations related to dedolomitisation. As the salt domes contain facies that are in all aspects identical to the deeply buried Ara play in the South Oman Salt Basin, this study provides substantial additional information for hydrocarbon exploration in South Oman. In addition, our work has implications for the hydrocarbon prospectivity of the Ghaba Salt Basin and possibly of other Ediacaran-Early Cambrian evaporite basins in the Middle East such as for the time-equivalent ‘Hormuz' salt basins.

  5. Paleosols of middle Holocene age in the Thakkhola basin, central Nepal, and their paleoclimatic significance

    Science.gov (United States)

    Saijo, Kiyoshi; Tanaka, Satoshi

    2002-12-01

    The characteristics and climatic implication of paleosols widely distributed in the Thakkhola basin, upper Kali Gandaki, central Nepal, were investigated. The paleosols were buried in surficial deposits of eolian or colluvial origin. They were composed not only of humus, but also included abundant inorganic matter. Some of them yielded charcoal fragments, pollen, and phytoliths. Radiocarbon dating suggested that the paleosols formed between 6200 and 4500 yr B.P., i.e. during the middle Holocene. The paleosols are interpreted to indicate stronger summer monsoons and increased rainfall at the time of their formation. The vegetation cover at that time is thought to have been relatively dense. Charcoal, plant fossils, and carbon isotope data suggest that grasslands were dominant in the northern part of the basin while trees grew in the southernmost part during the period of paleosol formation. The paleosols were buried by surficial deposits under drier climatic conditions after 4500 yr B.P.

  6. Robust assessment of future changes in extreme precipitation over the Rhine basin using a GCM

    Directory of Open Access Journals (Sweden)

    S. F. Kew

    2010-11-01

    Full Text Available Estimates of future changes in extremes of multiday precipitation sums are critical for estimates of future discharge extremes of large river basins. Here we use a large ensemble of global climate model SRES A1b scenario simulations to estimate changes in extremes of 1–20 day precipitation sums over the Rhine basin, projected for the period 2071–2100 with reference to 1961–1990.

    We find that in winter, an increase of order 10%, for the 99th percentile precipitation sum, is approximately fixed across the selected range of multiday sums, whereas in summer, the changes become increasingly negative as the summation time lengthens. Explanations for these results are presented that have implications for simple scaling methods for creating time series of a future climate. We show that this scaling behavior is sensitive to the ensemble size and indicate that currently available discharge estimates from previous studies are based on insufficiently long time series.

  7. Environmental setting and water-quality issues of the Mobile River Basin, Alabama, Georgia, Mississippi, and Tennessee

    Science.gov (United States)

    Johnson, Gregory C.; Kidd, Robert E.; Journey, Celeste A.; Zappia, Humbert; Atkins, J. Brian

    2002-01-01

    The Mobile River Basin is one of over 50 river basins and aquifer systems being investigated as part of the U.S. Geological Survey National Water-Quality Assessment (NAWQA) Program. This basin is the sixth largest river basin in the United States, and fourth largest in terms of streamflow, encompassing parts of Alabama, Georgia, Mississippi, and Tennessee. Almost two-thirds of the 44,000-square-mile basin is located in Alabama. Extensive water resources of the Mobile River Basin are influenced by an array of natural and cultural factors. These factors impart unique and variable qualities to the streams, rivers, and aquifers providing abundant habitat to sustain the diverse aquatic life in the basin. Data from Federal, State, and local agencies provide a description of the environmental setting of the Mobile River Basin. Environmental data include natural factors such as physiography, geology, soils, climate, hydrology, ecoregions, and aquatic ecology, and human factors such as reservoirs, land use and population change, water use, and water-quality issues. Characterization of the environmental setting is useful for understanding the physical, chemical, and biological characteristics of surface and ground water in the Mobile River Basin and the possible implications of that environmental setting for water quality. The Mobile River Basin encompasses parts of five physiographic provinces. Fifty-six percent of the basin lies within the East Gulf section of the Coastal Plain Physiographic Province. The remaining northeastern part of the basin lies, from west to east, within the Cumberland Plateau section of the Appalachian Plateaus Physiographic Province, the Valley and Ridge Physiographic Province, the Piedmont Physiographic Province, and the Blue Ridge Physiographic Province. Based on the 1991 land-use data, about 70 percent of the basin is forested, while agriculture, including livestock (poultry, cattle, and swine), row crops (cotton, corn, soybeans, sorghum, and wheat), and pasture land accounts for about 26 percent of the study unit. Agricultural land use is concentrated along the Black Prairie Belt district of the Coastal Plain. Urban areas account for only 3 percent of the total land use; however, the areal extent of the metropolitan statistical areas (MSA) may indicate more urban influences. The MSAs include urban areas outside of the city boundaries and can include adjacent counties. Seven MSAs are delineated in the Mobile River Basin, including Montgomery, Mobile, Tuscaloosa, Birmingham, Gadsden, Anniston, and Atlanta. The total population for the Mobile River Basin was about 3,673,100 in 1990. State water-quality agencies have identified numerous causes and sources of water-body impairment in the Mobile River Basin. In 1996, organic enrichment, dissolved oxygen depletion, elevated nutrient concentrations, and siltation were the most frequently cited causes of impairment, affecting the greatest number of river miles. Bacteria, acidic pH, and elevated metal concentrations also were identified as causes of impairment. The sources for impairment varied among river basins, were largely a function of land use, and were attributed primarily to municipal and industrial sources, mining, and agricultural activities.

  8. Mosquito larval habitat mapping using remote sensing and GIS: Implications of coalbed methane development and the West Nile Virus

    Science.gov (United States)

    Potential larval habitats of the mosquito Culex tarsalis (Coquillett), implicated as a primary vector of West Nile virus in Wyoming, were identified using integrated remote sensing and geographic information sytem (GIS) analyses. The study area is in the Powder River Basin of north central Wyoming,...

  9. Reconstruction of deformed North Pyrenean basin

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, J.A.

    1985-02-01

    The North Pyrenean basin in southern France was initiated in middle Cretaceous time along the North Pyrenean fault zone. An understanding of the middle Cretaceous is critical because it corresponds in time to opening in the Bay of Biscay, to postulated strike-slip along the North Pyrenean fault, to a controversially dated episode of metamorphism, and to emplacement of lherzolite. A field study of the Albian and Cenomanian fill of the North Pyrenean basin has been undertaken in order to provide constraints on postulated regional relationships during this time. Two steps are required for the study. The first is to reconstruct the structure of the basin that was deformed during the Late Cretaceous to Oligocene Pyrenean orogeny. The orogeny is here summarized as a north-south shortening that reactivated the North Pyrenean fault zone as a north-vergent reverse fault. Dominantly south-directed thrusting followed, and detachment along incompetent Triassic shale and evaporite layers was important in both phases. The second step is a sedimentologic analysis. The basin fill is dominantly marine, clastic mud, up to 4 km thick. Abrupt lateral thickness and facies variations demonstrate that the basin was bounded by active faults. Excepting the absence of high organic productivity, reconstruction suggests that the North Pyrenean basin is a partial analog in terms of geometry, facies arrangement, and regional setting to Cenozoic marine basins in California, particularly to those in which Monterey Formation lithologies were deposited.

  10. 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)

  11. Deleware Basin Monitoring Annual Report

    International Nuclear Information System (INIS)

    The Delaware Basin Drilling Surveillance Program (DBDSP) is designed to monitor drilling activities in the vicinity of the Waste Isolation Pilot Plant (WIPP). This program is based on Environmental Protection Agency (EPA) requirements. The EPA environmental standards for the management and disposal of transuranic (TRU) radioactive waste are codified in 40 CFR Part 191 (EPA 1993). Subparts B and C of the standard address the disposal of radioactive waste. The standard requires the Department of Energy (DOE) to demonstrate the expected performance of the disposal system using a probabilistic risk assessment or performance assessment (PA). This PA must show that the expected repository performance will not release radioactive material above limits set by the EPA's standard. This assessment must include the consideration of inadvertent drilling into the repository at some future time.

  12. Delaware Basin Monitoring Annual Report

    International Nuclear Information System (INIS)

    The Delaware Basin Drilling Surveillance Program (DBDSP) is designed to monitor drilling activities in the vicinity of the Waste Isolation Pilot Plant (WIPP). This program is based on Environmental Protection Agency (EPA) requirements. The EPA environmental standards for the management and disposal of transuranic (TRU) radioactive waste are codified in 40 CFR Part 191 (EPA 1993). Subparts B and C of the standard address the disposal of radioactive waste. The standard requires the Department of Energy (DOE) to demonstrate the expected performance of the disposal system using a probabilistic risk assessment or performance assessment (PA). This PA must show that the expected repository performance will not release radioactive material above limits set by the EPA's standard. This assessment must include the consideration of inadvertent drilling into the repository at some future time.

  13. Characteristic basin water storage behavior using GRACE

    Science.gov (United States)

    Reager, J. T.; Famiglietti, J. S.

    2011-12-01

    A long-standing challenge for hydrologists has been a lack of observational data on internal basin hydrological behavior, and historically, various models and assumptions have been postulated to facilitate an operational relationship between runoff response and precipitation forcing. With NASA's Gravity Recovery And Climate Experiment (GRACE) mission, hydrologists are finally able to observe terrestrial water storage anomaly time series for large basins (>150,000 km^2) with monthly resolution. These data are ideally suited for monitoring global water storage variability and classifying differences in large-scale water storage behavior. Here we provide results of a frequency-domain analysis of basin-averaged GRACE terrestrial water storage and Global Precipitation Climatology Project (GPCP) precipitation. We calculate frequency-domain transfer functions of storage response to precipitation forcing, and then parameterize these transfer functions based on large-scale basin characteristics, such as ecosystem type and basin temperature. This results in a basin-independent model of scaled storage response to precipitation forcing as a function of temporal frequency and large-scale basin characteristics, quantifying fundamental global hydrology relationships that were previously unobservable. Results show that temperature and land cover type are the major controls on relative storage variability. At annual timescales, temperature variability dominates storage variability for basins with a mean temperature under 15 deg C, while land cover type controls storage variability for warmer basins. At interannual timescales, land cover type alone is the single largest influence on storage behavior in all basins, with forested basins showing a greater ``buffer effect`` to interannual variability in precipitation forcing. These relationships are used to validate our method by predicting storage anomaly outside the observed data range. Finally, we show a coupling of variability in vegetation and storage as a function of basin wetness. While the model presented does not account for nonlinear transitions between ecosystem types, within the limits of a stable ecosystem it offers the first reliable means for predicting a large-scale state variable forced by precipitation, temperature and land cover classification.

  14. K Basins isolation barriers summary report

    Energy Technology Data Exchange (ETDEWEB)

    Strickland, G.C., Westinghouse Hanford

    1996-07-31

    The 105-K East and 105-K West fuel storage basins (105-K Basins) were designed and constructed in the early 1950`s for interim storage of irradiated fuel following its discharge from the reactors. The 105-K- East and 105-K West reactor buildings were constructed first, and the associated storage basins were added about a year later. The construction joint between each reactor building structure and the basin structure included a flexible membrane waterstop to prevent leakage. Water in the storage basins provided both radiation shielding and cooling to remove decay heat from stored fuel until its transfer to the Plutonium Uranium Extraction (PUREX) Facility for chemical processing. The 105-K West Reactor was permanently shut down in February 1970; the 105-K East Reactor was permanently shut down in February 1971. Except for a few loose pieces, fuel stored in the basins at that time was shipped to the PUREX Facility for processing. The basins were then left idle but were kept filled with water. The PUREX Facility was shut down and placed on wet standby in 1972 while N Reactor continued to operate. When the N Reactor fuel storage basin began to approach storage capacity, the decision was made to modify the fuel storage basins at 105-K East and 105-K West to provide additional storage capacity. Both basins were subsequently modified (105-K East in 1975 and 105-K West in 1981) to provide for the interim handling and storage of irradiated N Reactor fuel. The PUREX Facility was restarted in November 1983 to provide 1698 additional weapons-grade plutonium for the United States defense mission. The facility was shut down and deactivated in December 1992 when the U.S. Department of Energy (DOE) determined that the plant was no longer needed to support weapons-grade plutonium production. When the PUREX Facility was shut down, approximately 2.1 x 1 06 kg (2,100 metric tons) of irradiated fuel aged 7 to 23 years was left in storage in the 105-K Basins pending a decision on final disposition of the material. The Hanford Federal Facility Agreement and Consent Order (Ecology et al. 1994), also known as the Tri-Party Agreement, commits to the removal of all fuel and sludge from the 105-K Basins by the year 2002.

  15. Permian-Triassic maturation and multistage migration of hydrocarbons in the Assistência Formation (Irati Subgroup), Paraná Basin, Brazil: implications for the exploration model / Maturação permotriássica e os vários estágios de migração de hidrocarbonetos na Formação Assistência (Subgrupo Irati), Bacia do Paraná: implicações para os modelos exploratórios

    Scientific Electronic Library Online (English)

    António, Mateus; Claudio, Riccomini; Ezequiel J. E. C. B., Ferreira; Colombo C. G., Tassinari.

    2014-09-01

    Full Text Available Novas linhas de evidências geológicas sugerem fortemente que o principal período de maturação de hidrocarbonetos na Formação Assistência teria ocorrido no Permotriássico, estimulado por um gradiente geotérmico elevado que também sustentou várias manifestações de atividade hidrotermal. Três fases pri [...] ncipais de migração de fluidos e hidrocarbonetos também podem ser inferidas a partir de observações em multiescala: fluxo confinado no final do Permiano ao Triássico, dependente do acúmulo local de pressões de fluidos; fluxo heterogêneo no Cretáceo Inferior, desencadeado por um gradiente de temperatura rejuvenescido, assistido pelas condições de permeabilidade antes desenvolvidas; e um fluxo tardio, possivelmente impulsionado por gradientes de pressão locais, posteriormente ao esfriamento dos diques e soleiras de diabásio. A maturação precoce e a existência de vários estágios de migração de hidrocarbonetos apresentam implicações significativas na concepção de modelos exploratórios a serem aplicados na Bacia do Paraná. Abstract in english New lines of geological evidence strongly suggest that the main period of hydrocarbon maturation within Assistência Formation should be Permian-Triassic, stimulated by a high geothermal gradient that also sustained various manifestations of hydrothermal activity. Three main stages of fluid/hydrocarb [...] on migration can also be inferred on the basis of multiscale observations: confined flow in late Permian to Triassic times, depending on the local build-up of fluid pressures; heterogeneous flow in Lower Cretaceous, triggered by a rejuvenated temperature gradient assisted by the early developed permeability conditions; and a late flow possibly driven by local pressure gradients, after complete cooling of dolerite dykes/sills. The early maturation and multistage migration of hydrocarbons have significant consequences in the design of exploration models to be applied in Paraná Basin.

  16. Late orogenic intramontane basin development: the Granada basin, Betics (southern Spain)

    OpenAIRE

    Rodríguez-Fernández, José; Sanz de Galdeano, Carlos

    2006-01-01

    The quantitative study of subsidence in the Granada basin, using decompaction and backstripping techniques, and contemporaneous relief development in the surrounding areas, especially in the Sierra Nevada, provides a good case example of the development of an intramontane basin. In the Granada basin, according to the interpretation of the seismic profiles and results of the backstripping analysis, subsidence and sedimentation rates were at a maximum in the late Tortonian and decreased progres...

  17. Orphan Basin, offshore Newfoundland : new seismic data and hydrocarbon plays for a dormant Frontier Basin

    Energy Technology Data Exchange (ETDEWEB)

    Smee, J. [G and G Exploration Consulting, Calgary, AB (Canada)

    2003-07-01

    The Orphan Basin is one of the few remaining Canadian frontier areas that has the potential to become a significant source of petroleum. It is located in deep waters, 370 km off the coast of Newfoundland and is bounded by the Bonavista platform and the Jeanne d'Arc and Flemish Pass basins. Well control in the Basin is very sparse. The Texaco Shell, Blue H-28 well is the only exploration well drilled in the Basin. It was drilled on a basement high and encountered thin Mesozoic and Paleozoic sediments. Seismic control has improved in the Orphan Basin during the past 3 years. A 10,449 km regional program was shot in 2000, followed by a 6,844 km program in 2001, and a 1,295 km program in 2002. New data has provided greater penetration and imaging at depth, providing a better understanding of the geologic history and hydrocarbon potential of the area. The geologic evolution of the Orphan Basin is similar to that of the Jeanne d'Arc and Flemish Pass basins. All the basins began to form in the Late Triassic as rift basins developed. The Late Jurassic was a critical time for the development of petroleum systems. Major tectonism resulted in the Mesozoic section being structured into several potentially attractive hydrocarbon traps that can be documented and mapped with modern seismic methods. The traps include anticlinal structures, tilted fault blocks and overlap pinchout plays. 5 refs., 5 figs.

  18. BASIN STRUCTURE FROM TWO-DIMENSIONAL SEISMIC REFLECTION DATA, CRAZY MOUNTAINS BASIN, MONTANA

    Energy Technology Data Exchange (ETDEWEB)

    David J. Taylor

    2003-08-01

    Some 140 miles of multichannel seismic reflection data, acquired commercially in the 1970's, were reprocessed by the U.S. Geological Survey in late 2000 and early 2001 to interpret the subsurface geology of the Crazy Mountains Basin, an asymmetric Laramide foreland basin located in south-central Montana. The seismic data indicate that the northwestern basin margin is controlled by a thrust fault that places basement rocks over a thick (22,000 feet) sequence of Paleozoic and Mesozoic sedimentary rocks to the south. From the deep basin trough, Paleozoic through Tertiary rocks slope gently upward to the south and southeast. The northern boundary of the basin, which is not imaged well by the seismic data, appears to be folded over a basement ridge rather than being truncated against a fault plane. Seismic data along the basin margin to the south indicate that several fault controlled basement highs may have been created by thin-skinned tectonics where a series of shallow thrust faults cut Precambrian, Paleozoic, and early Mesozoic rocks, whereas, in contrast, Cretaceous and Tertiary strata are folded. The data are further interpreted to indicate that this fault-bounded asymmetric basin contains several structures that possibly could trap hydrocarbons, provided source rocks, reservoirs, and seals are present. In addition, faults in the deep basin trough may have created enough fracturing to enhance porosity, thus developing ''sweet spots'' for hydrocarbons in basin-centered continuous gas accumulations.

  19. GOSSYPIBOMA AND ITS IMPLICATIONS

    OpenAIRE

    Umunna, JI

    2012-01-01

    Surgical materials are sometimes inadvertently left in the body after surgical operations. Cotton materials are the commonest objects forgotten. The implications for the patient and the surgeon are grave. The purpose of this presentation is to rekindle awareness of the phenomenon of gossypiboma, highlight the implications and stress prevention. Data were collected from hospital records which included their demographics, clinical features, management outcome and follow-up. Four cases of gossyp...

  20. Comparison of GRACE with in situ hydrological measurement data shows storage depletion in Hai River basin, Northern China

    Scientific Electronic Library Online (English)

    Juana Paul, Moiwo; Yonghui, Yang; Huilong, Li; Shumin, Han; Yukun, Hu.

    2009-10-01

    Full Text Available Water storage change has implications not only for the hydrological cycle, but also for sustainable water resource management in especially semi-arid river basins. Satellite/remote sensing techniques have gained increasing application in monitoring basin and regional hydrological processes in recent [...] decades. In this study, the latest version of GRACE (Gravity Recovery and Climate Experiment) is used to estimate total water storage change in the Hai River basin (HRB) of Northern China for the period January 2003 to December 2006. Time-series comparisons show a good agreement between the estimated storage change from the GRACE satellite data and in situ hydrological measurement data at especially the seasonal cycle with R = 0.82 and RMSE = 17.25 mm. The good agreement suggests that GRACE detects storage change in the 318 866 km² HRB study area. It also implies that the in situ hydrological measurements of soil moisture and groundwater sufficiently characterise storage change in the semi-arid river basin. Change in soil moisture storage is less than that in saturated storage, suggesting that storage depletion in the basin is mainly in the saturated zone. Both the GRACE and hydrological measurement data indicate storage loss in the range of 12.72 to 23.76 mm/yr - a phenomenon that has been detected in previous studies in the basin. GRACE hydrology data could therefore be handy in monitoring storage dynamics and water availability in the study area. As GRACE data are available for virtually every region of the world, their application in conjunction with hydrological models could improve hydrological studies. This may lead not only to water balance closures, but also to sustainable water resource management at basin to regional scale.

  1. Impacts of Change in Irrigation Water Availability on Food Production in the Yellow River Basin under Climate Change

    Science.gov (United States)

    Yin, Y. Y.; Tang, Q.

    2014-12-01

    Approximately 9 percent of China's population and 17 percent of its agricultural area are settled in the Yellow River Basins. Irrigation, which plays an important role in agricultural production, occupies the largest share of human consumptive water use in the basin. Given increasing water demands, the basin faces acute water scarcity. Previous studies have suggested that decrease in irrigation water availability under climate change might have an overall adverse impact on the food production of the basin. The timing and area that would face severe water stress are yet to be identified. We used a land surface hydrological model forced with the bias-corrected climatic variables from 5 climate models under 4 Representative Concentration Pathways (RCPs) to estimate total water availability in the sub-basins of the Yellow River basin. The future socioeconomic conditions, the Shared Socioeconomic Pathways (SSPs), were used to estimate the water requirement in the nonagricultural water use sectors. The irrigation water availability was estimated from the total water availability and nonagricultural water use, and the irrigation water demands were estimated based on the current irrigation project efficiencies. The timing and area of irrigation water shortage were shown and the implication of change in irrigation water availability on food production was assessed. The results show that the sub-basins with high population density and gross domestic product (GDP) are likely to confront severe water stress and reduction in food production earlier because irrigation water was to be appropriated by the rapid increase in nonagricultural water use sectors. The study stresses the need for adaptive management of water to balance agriculture and nonagricultural demands in northern China.

  2. K-Basins S/RIDS

    Energy Technology Data Exchange (ETDEWEB)

    Watson, D.J.

    1997-08-01

    The Standards/Requirements Identification Document (S/RID) is a list of the Environmental, Safety, and Health (ES{ampersand}H) and Safeguards and Security (SAS) standards/requirements applicable to the K Basins facility.

  3. USGS Streamgage NHDPlus Version 1 Basins 2011

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This dataset represents 19,031 basin boundaries and their streamgage locations for the U.S. Geological Survey's (USGS) active and historical streamgages from the...

  4. Klamath Basin Water Rights Place of Use

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Hydrological Information Products for the Off-Project Water Program of the Klamath Basin Restoration Agreement U.S. Geological Survey Open-File Report 2012-1199...

  5. Overflow of Radioactive Water from K Basins

    Energy Technology Data Exchange (ETDEWEB)

    RITTMANN, P.D.

    1999-10-06

    This report documents the dose calculations for the postulated K Basin overflow accident using current methods to model the environmental doses for radioactive releases into the Columbia River and the air.

  6. Cretaceous Onlap, Gulf of Mexico Basin [cretonlapg

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The maximum extent of Cretaceous onlap is generalized from Plate 3, Structure at the base and subcrop below Mesozoic marine section, Gulf of Mexico Basin (compiled...

  7. Integrated geophysical model of the Thuringian Basin

    Science.gov (United States)

    Bleibinhaus, F.; Krause, M.; Jahr, T.; Vinzelberg, D.; Prutkin, I.; Goepel, A.; Kukowski, N.

    2013-12-01

    The INFLUINS (INtegrated FLUid dynamics IN Sedimentary basins) project aims at an improved understanding of the coupled fluid flow in sedimentary basins from the shallow aquifers to the deep layers. Hydrological, geological and geophysical investigations of the Thuringian Basin, Germany, provide a site characterization at various scales that is the basis for dynamic flow models. This study presents an integrated geophysical and structural approach that combines seismic and gravimetric observations with borehole data and surface geology. The seismic data consists of three reflection-seismic lines across the center of the basin providing high-resolution structural images. Additional piggyback recordings provide the basis for a tomographic 3D model of seismic velocities. Those studies are complemented by a 3D density model from a 2D grid of measuring points and several dense gravimetric profiles. The geophysical models provide layer thickness variations and rock properties, and, together with surface mapping, an inventory of faults, which are important prerequisites for subsequent flow models.

  8. K-Basins S/RIDS

    Energy Technology Data Exchange (ETDEWEB)

    Watson, D.J.

    1995-09-22

    The Standards/Requirements Identification Document(S/RID) is a list of the Environmental, Safety, and Health (ES&H) and Safeguards and Security (SAS) standards/requirements applicable to the K Basins facility

  9. NWS Integrated Hydrologic Automated Basin Boundary System

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOHRSC provides and maintains the NWS Integrated Hydrologic Automated Basin Boundary System (IHABBS) GIS database to support river and flood forecasting...

  10. K-Basins S/RIDS

    International Nuclear Information System (INIS)

    The Standards/Requirements Identification Document (S/RID) is a list of the Environmental, Safety, and Health (ES(ampersand)H) and Safeguards and Security (SAS) standards/requirements applicable to the K Basins facility

  11. 183-H Basin sludge treatability test report

    International Nuclear Information System (INIS)

    This document presents the results from the treatability testing of a 1-kg sample of 183-H Basin sludge. Compressive strength measurements, Toxic Characteristic Leach Procedure, and a modified ANSI 16.1 leach test were conducted

  12. Gulf Coast Basins and Uplifts [gcstructsg

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — These data provide generalized outlines of major basins and uplifts in the Gulf Coast region modified after Plate 2, Principal structural features, Gulf of Mexico...

  13. Implementation of strategic environmental assessment in Serbia: Case of spatial plan of Kolubara lignite basin

    Directory of Open Access Journals (Sweden)

    Mari?i? Tamara

    2006-01-01

    Full Text Available Although considered as an important tool for environmental evaluation of plans and programmes, inclusion of strategic environmental assessment (SEA in Serbian legislation was inevitable as a part of the accession process to the European Union. The first part of this paper will focus on presentation of the SEA system in Serbia and its implication as the result of current geopolitical and environmental trends. Taking into consideration the economic importance of the mining regions, but also the damage to the surrounding environment, in the second part of this paper the authors will try to review the significance of SEA implementation in spatial planning of Kolubara lignite basin.

  14. Sediment supply as a driver of river evolution in the Amazon Basin

    Science.gov (United States)

    Ahmed, Joshua; Constantine, José Antonio; Dunne, Thomas; Legleiter, Carl; Lazarus, Eli D.

    2015-04-01

    The Amazon represents the only large river basin in the world where there is a sufficient range of sediment supplies and a lack of engineering controls to assess how sediment supply drives the evolution of meandering rivers. Despite recent analytical advances (Asahi et al., 2013; Pittaluga and Seminara, 2011), modern theory does not yet identify or explain the effects of externally imposed sediment supplies, a fundamental river characteristic, on meandering river evolution. These sediment supplies would be radically reduced by the construction of large dams proposed for the Amazon Basin (Finer and Jenkins, 2012). Here, we demonstrate that the sediment loads imposed by their respective drainage basins determine planform changes in lowland rivers across the Amazon. Our analysis, based on Landsat image sequences, indicates that rivers with high sediment loads draining the Andes and associated foreland basin experience annual migration rates that are on average four times faster than rivers with lower sediment loads draining the Central Amazon Trough and shields. Incidents of meander cutoff also occur more frequently along the rivers of the Andes and foreland basin, where the number of oxbows in the floodplains is more than twice that observed in the floodplains of the Central Amazon Trough and shields. Our results, which cannot be explained by differences in channel slope or hydrology, highlight the importance of sediment supply in modulating the ability of meandering alluvial rivers to reshape the floodplain environment through river migration. Asahi, K., Shimizu, Y., Nelson, J., Parker, G., 2013. Numerical simulation of river meandering with self-evolving banks. Journal of Geophysical Research: Earth Surface, 118(4), 2013JF002752. Finer, M., Jenkins, C.N., 2012. Proliferation of hydroelectric dams in the Andean Amazon and implications for Andes-Amazon connectivity. PLOS One, 7(4), e35126. Pittaluga, M.B., Seminara, G., 2011. Nonlinearity and unsteadiness in river meandering: a review of progress in theory and modelling. Earth Surface Processes and Landforms, 36(1), 20-38.

  15. Thermal maturity and hydrocarbon generation in rocks from the sedimentary basins of Madagascar

    Energy Technology Data Exchange (ETDEWEB)

    Ramanampisoa, L. (Office Militaire National pour les Industries Strategiques (OMNIS), Antananarivo (Madagascar). Hydrocarbon Dept.); Radke, M. (Kernforschungsanlage Juelich GmbH (Germany). Inst. of Petroleum and Organic Geochemistry)

    1992-10-01

    The present study at the Morondava Basin was originally related mostly to geochemical prospect appraisal. Due to the uniform organic matter type and wide range of thermal evolution stages sampled, the case history has more general implications, however, as regards relationships between thermal maturation and hydrocarbon generation. Evaluation of eleven rock samples taken at depths of between 1,100 and 2,500m by RockEval, solvent extraction and vitrinite reflectance (R[sub r]) methods revealed only poor source rocks for oil with marginal through to post-mature Type III kerogens (R[sub r] between 0.5% and 1.4%). Discrepancies in yield profiles of total C[sub 15+]-hydrocarbons peaking at higher R[sub r] in the Moronodava and Douala Basin (Cameroon) wells than in a Deep Basin (West Canada) well are tentatively attributed to their different geothermal histories. However, yield trends of specific saturated and aromatic hydrocarbon families, as determined by capillary gas chromatography, did not testify to the suspected effect of geothermal rate variations on generation curves, which hence remain unproven. Based on systematic changes with depth in the distribution of methylated di- and tri-aromatics, the interpretation of maturation levels with respect to hydrocarbon generation was refined. When converted to vitrinite reflectance equivalents (R[sub c]), molecular parameters such as the Trimethylnaphthalene Ratio (TRN 1) and the Methylphenanthrene Index (MPI 1) were able to disclose gradual maturity changes. In contrast to the large Moronodava Basin, the smaller Majunga Basin in NW Madagascar has been the site of little exploration activity until recently. Based on organic-geochemical analysis of seven rock samples from two exploration wells by the above-mentioned methods, it was found that good source rocks for oil are absent. Some of the samples may have a considerable gas generation potential, which at best has been partially realised. (author)

  16. Critically safety evaluation for K Basins sandfilters

    International Nuclear Information System (INIS)

    Criticality safety for K Basins sandfilters was considered. No credible normal or off-normal scenarios were determined which could compromise criticality safety and result in a Keff ? 0.98. The conclusion is that, due to the physical form and isotopic distribution of the fissionable material, there is no possibility of a nuclear criticality in the sandfilter. For this reason, there is no need for a criticality alarm system for the K Basins sandfilters

  17. Geo-economy of the Caspian basin

    International Nuclear Information System (INIS)

    The Caspian area is essential for the development of the central Asia countries and Caucasus. Excepted the Iran and the Russia, these areas economy is poor. The hydrocarbons exploitation should reinforce the economic weight of these States. The author analyzes the Caspian area economies and shows that the basin economies are confronted with three handicaps, and that even with different economic ways, the soviet economic system is still present in the basin. (A.L.B.)

  18. THE RIVER BASIN APPROACH IN TOURISM PLANNING

    OpenAIRE

    Slara, Agita

    2005-01-01

    The article describes advantages and disadvantages in tourism planning, using the river basins as background territory and borders. Tourism development planning is taking place according administrative territorial borders till nowadays in Latvia and in other tourism destinations in abroad. According tourist and visitor needs and environmental friendly approach it is more appropriate to use river basins in tourism planning. Tourists are not interested in administrative borders, but in qualitat...

  19. Critically safety evaluation for K Basins sandfilters

    Energy Technology Data Exchange (ETDEWEB)

    Wittekind, W.D.

    1994-10-01

    Criticality safety for K Basins sandfilters was considered. No credible normal or off-normal scenarios were determined which could compromise criticality safety and result in a K{sub eff} {>=} 0.98. The conclusion is that, due to the physical form and isotopic distribution of the fissionable material, there is no possibility of a nuclear criticality in the sandfilter. For this reason, there is no need for a criticality alarm system for the K Basins sandfilters.

  20. DISLOCACIÓN DE FACIES EN EL TOPE DE LA SECUENCIA CRETÁCICA DE LA SUBCUENCA DE NEIVA, VALLE SUPERIOR DEL MAGDALENA Y SUS IMPLICACIONES EN EL MODELO ESTRATIGRÁFICO SECUENCIAL COLOMBIANO / FACIES DISLOCATION ON TOP OF THE CRETACEOUS SEQUENCE OF THE NEIVA SUB-BASIN, UPPER MAGDALENA VALLEY, IMPLICATIONS IN THE SEQUENTIAL STRATIGRAPHIC MODEL OF COLOMBIA

    Scientific Electronic Library Online (English)

    Gabriel Eduardo, Veloza; Andres, Mora A; Mario, De Freitas; Mario, Mantilla.

    2008-06-01

    Full Text Available La identificación de un abrupto cambio de facies y ambientes de depósito entre los sedimentos de la llamada Formación Monserrate y la Formación San Francisco del Grupo Guaduala, permite reconocer una Dislocación de Facies en el tope de la secuencia marina del Cretácico colombiano en el Valle Superio [...] r del Magdalena, atribuida al levantamiento de la Cordillera Central y a la acreción de bloques tectónicos al Oeste del Sistema de Fallas de Romeral. Utilizando la integración de análisis detallados de sedimentología y estratigrafía en secciones de superficie y registros de pozos, se identificó la existencia de ambientes de depósito variantes entre el frente de costa medio y costa afuera proximal, que dominan la Formación Monserrate, mientras ambientes proximales, principalmente de lagos, pantanos y llanuras de inundación han sido interpretados para la Formación San Francisco. La ausencia de registro estratigráfico de la regresión de facies, desde ambientes marinos distales hasta ambientes continentales evidencia la discordancia o relación paraconforme de éstas unidades, donde los sedimentos de ambientes proximales fueron erodados o "bypassed". Esta superficie y sus superficies correlativas deben ser interpretadas como el límite de la secuencia marina del Cretácico colombiano y estarían evidenciando además, la primera fase del levantamiento pre-Andino. Abstract in english The identification of an abrupt facies change between the Monserrate and San Francisco formations allows us to identify a Facies Dislocation on top of the Cretaceous marine sequence of the Neiva sub-basin, due to the uplift of the Central Cordillera and the accretion of tectonic blocks, west of the [...] Romeral Fault Zone. With an integrated detailed stratigraphic analysis in surface sections and wells, marine environments were identified for the Monserrate Formations, ranging from near offshore to middle shoreface. For the San Francisco Formation, continental environments were identified, ranging from coastal to fluvial plain, swamps and paleosoils. The lack of all the regression of facies, from deep marine environments to the continental realm is the principal evidence of the paraconformity between those units, implying that sediments from proximal environments were eroded or bypassed. This surface and their correlative surfaces have to be interpreted as the boundary of the marine sequence of the Cretaceous of Colombia in this area, and gives an evidence of the first pre-Andean uplift.

  1. Tafofacies y biofacies de la Formación Vaca Muerta en el sector surmendocino de la Cuenca Neuquina: implicancias paleoecológicas, sedimentológicas y estratigráficas / Taphofacies and biofacies of the Vaca Muerta Formation in the southern Mendoza sector of the Neuquén Basin: paleoecological, sedimentological and stratigraphic implications

    Scientific Electronic Library Online (English)

    Diego Alejandro, Kietzmann; Ricardo Manuel, Palma.

    2009-06-01

    Full Text Available Se realizaron estudios tafonómicos y paleoecológicos de las asociaciones fósiles en las sucesiones transgresivas y de mar alto de la Formación Vaca Muerta (Tithoniano inferior - Valanginiano superior) de las secciones del arroyo Loncoche, arroyo Rahue y Cuesta del Chihuido, provincia de Mendoza. Sob [...] re la base de la integración de estudios tafonómicos y biofaciales, y litofaciales y microfaciales previos, se determinaron distintos subambientes de la rampa carbonática, que incluyen rampa media, rampa externa y cuenca. En la zona de rampa media se reconocieron las siguientes tafofacies: dos tipos de autopa-rabiostromas, así como concentraciones de bivalvos, gastrópodos y serpúlidos; mientras que las biofacies incluyen autobiostromas ricos en grifeidos y serpúlidos. En la zona de rampa externa se reconocieron dos tipos de parabiostromas, pavimentos de amonites y ápticos, detritos bioclásticos, pavimentos de moluscos y braquiópodos, además de calizas nodulares bioturbadas y amonites truncados. En esta zona las biofacies están caracterizadas por una alta diversidad que incluye: Lingularia-Discinisca, bivalvos infaunales, foraminíferos epistomínidos, bivalvos filamentosos, además de pectínidos, ostreidos e inocerámidos, sustratos endurecidos así como matas microbianas. El estudio de tafofacies y biofacies permitió estimar cambios relativos del nivel del mar, tasas de sedimentación, consistencia del sustrato, oxigenación, nutrientes y niveles de productividad. Abstract in english Taphonomic and paleocological studies of fossil assemblages from the transgressive and highstand succession of the Vaca Muerta Formation (lower Tithonian to upper Valanginian) in Loncoche Creek, Rahue Creek and Cuesta del Chihuido, Mendoza province, was carried out. A range of paleoenvironments that [...] include mid, outer and basin deposits of carbonate ramp have been determinated based on integrated studies of taphofacies, biofacies, lithofacies and microfacies. In the mid ramp zone were recognized the following taphofacies: two types of autoparabiostromes, as well as concentrations of bivalves, gastropods and serpulids. Meanwhile, biofacies included autobiostromes rich in grypheids and serpulids. In the outer ramp zone were recognized two types of parabiostromes, ammonite and aptychus pavements, bioclastic detritus, molluscs and brachiopods pavements, besides bioturbated nodular limestones and truncated ammonites. In this zone, biofacies are characterized by high diversity including: Lingularia-Discinisca, infaunal bivalves, epistominid foraminifers, filament bivalves, besides of pectinidae, oysters and inoceramid bi-valves, hardgrounds and microbial mats. Taphofacies and biofacies data allow to estimate relative sea level changes, sedimentation rates, substrate consistency, oxygenation, nutrient levels and productivity.

  2. Beidellite-nontronite clays in Neogene sediments from Cuitzeo-Charo lacustrine basin Michoacán, México: Geological setting and paleoenvironmental implications / Arcillas del tipo beidellita-nontronita en sedimentos neógenos de la cuenca lacustre Cuitzeo-Charo, Michoacán, México: Contexto geológico e implicaciones paleoambientales

    Scientific Electronic Library Online (English)

    Isabel, Israde-Alcántara; Jasinto, Robles-Camacho; José Manuel, Domínguez.

    Full Text Available Depósitos lacustres y fluviolacustres de la secuencia de Charo afloran a lo largo de decenas de kilómetros y sobreyacen las secuencias volcanicas del Mioceno del Complejo de Mil Cumbres en una cuenca orientada Este-Oeste. Al oeste de la ciudad de Morelia (centro oeste de Mexico), los estratos arcill [...] osos no litificados con espesores de 3 m son sobreyacidos por depósitos de diatomita masiva que se desarrollaron durante el Mioceno-Plioceno en el paleolago de Cuitzeo. Los mas grandes afloramientos están localizados al sur y este del poblado de Charo en Las Pulgas, Lomas Blancas y Tzitzimeo, todas conformando facies mineralógicas y correlación estratigrqfica similares. Estudios de campo, petrografía y espectrometría de rayos X (XRF) indican que la roca parental fue principalmente de composición andesítica con componentes menores de tipo dacitico y riolítico. La fuente de este material se localiza en los niveles estratigráficos del actual sistema regional de horst y grabens. Las arcillas diagenéticas fueron identificadas como esmectitas. La parte central de la columna de Las Pulgas muestra una asociación de beidellita-nontronita (B-N). Igualmente la 27Al-NMR y la espectrometría Móssbauer confirman el carácter B-N. Las diatomitas intercaladas y que sobreyacen estos depósitos arcillosos indican un ambiente lacustre que favoreció la incipiente estratificación (esmectitaillita), que se desarrolla favorablemente en la parte media de los estratos arcillosos. Abstract in english Lacustrine and fluviolacustrine deposits of the Charo sequence crop out extensively along tens of kilometres, and they overlie the Miocene volcanic sequences of the Mil Cumbres Complex in an E-W oriented basin. Eastwards of Morelia city (central Mexico), layers of non lithified clayey sediments of a [...] bout 3 m in thickness are overlaid by massive diatomite deposits developed during the Miocene-Pliocene in the Cuitzeo palaeolake. Major outcrops are located south and east of the village of Charo at the Las Pulgas, Lomas Blancas and Tzitzimeo sites; all having similar mineralogical facies and strati graphic correlation. Field studies, petrography and X-ray fluorescence spectrometry (XRF) indicated that the parent rock was mainly of andesitic composition with minor daciticrhyolitic components. The source of the raw material was located in the upper topographic levels of the present horst-graben system. The diagenetic clays were identified as smectites. The central part of the Las Pulgas column shows a beidellite-nontronite (B-N) association. Likewise, 27A1-NMR and Móssbauer spectroscopies confirm the B-N character. Interlaid and overlying diatomite strata indicate a lacustrine environment, favourable to the development of secondary clays. The stability of lacustrine conditions gave place to an incipient stratification (smectite-illite), better developed in the middle part of the clayey levels.

  3. California Basin Studies (CaBS)

    International Nuclear Information System (INIS)

    The California Continental Borderland's present configuration dates from about 4 to 5 X 106 years Before Present (B.P.) and is the most recent of several configurations of the southern California margin that have evolved after the North America Plate over-rode the East Pacific Rise about 30 X 106 years ago. The present morphology is a series of two to three northwest-southeast trending rows of depressions separated by banks and insular ridges. Two inner basins, Santa Monica and San Pedro, have been the site for the Department of Energy-funded California Basin Study (CaBS) Santa Monica and San Pedro Basins contain post-Miocene sediment thicknesses of about 2.5 and 1.5 km respectively. During the Holocene (past 10,000 years) about 10-12 m have accumulated. The sediment entered the basin by one or a combination of processes including particle infall (mainly as bioaggregates) from surface waters, from nepheloid plumes (surface, mid-depths and near-bottom), from turbidity currents, mass movements, and to a very minor degree direct precipitation. In Santa Monica Basin, during the last century, particle infall and nepheloid plume transport have been the most common processes. The former dominates in the central basin floor in water depths from 900 to 945 m. where a characteristic silt-clay with a typical mean diameter of about 0.006 mm, phi standard deviation

  4. River Basin Planning: Theory and Practice

    Science.gov (United States)

    Joeres, Erhard F.

    River Basin Planning is divided into three major parts and an appendix. Part 1, Theory of River Basin Planning, is led by an introductory chapter from the editors emphasizing the major human component in the complex sociotechnical attributes of river basin development. They present a forceful argument for a truly interdisciplinary approach to river basin planning. (The appendix subsequently suggests curriculum development for courses in river basin planning.)Part 2, River Basin Planning: Environmental Issues, is supported by two chapters: one with a focus on soil conservation, the other on ecosystem protection. The soil conservation chapter by I. Douglas illustrates that slow, inadvertent changes may be more damaging in the long run than immediate, direct effects. It postulates that planning for people perforce will require planning for soil conservation as an ongoing activity. The case for environmental protection is somewhat weak because of the singular example chosen for illustration. The Gunung Mulu National Park in Sarawak, Malaysia, is in a fragile, humid, tropical forest region where any change per se is interpreted as being detrimental.

  5. North Pyrenean interplate basin: Evolution and hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Bourrouilh, R.; Richert, J.; Zolnai, G.

    1988-08-01

    The Mesozoic-Tertiary North Pyrenean (Aquitaine) basin is situated between the Aquitaine margin to the north and the Iberian margin to the south. The birth and growth of the basin succeeded a complex Paleozoic history, which left an intricate lithological and structural heritage upon which the chessboard of Mesozoic subbasins developed. The history of the Aquitaine basin is a suite of attempts in the context of the progressive opening of the Bay of Biscay. Synchronous plate motion and later convergence led to the emergency of the Pyrenean foldbelt. The sedimentary filling of the basin comprises continental and evaporitic sequences, extensive marine carbon platforms, and massive flysch and molasse series, reflecting successive movements of increasing intensity. Appearance or revival of synchronous sedimentary and/or structural phenomena such as conjugated fault patterns, block tilting and block faulting, emplacement of mantelic remnants, halokinesis, olistostromes, and mass flows, together with the presence of plastic layers, contributed to shape an extremely complex final image. Gas and petroleum occurrence is controlled by the successive phases and anomalies of this history. The authors furthermore assert that events of the basin-forming extensional period contributed more to the generation of the actual hydrocarbon accumulations than did the effects of the subsequent compressive structural stresses. Geological models proposed by various authors will be reviewed and a general new model will be attempted for the evolution of the Aquitaine basin and the Pyrenees.

  6. K basins sludge removal sludge pretreatment system

    International Nuclear Information System (INIS)

    The Spent Nuclear Fuels Program is in the process of planning activities to remove spent nuclear fuel and other materials from the 100-K Basins as a remediation effort for clean closure. The 105 K- East and K-West Basins store spent fuel, sludge, and debris. Sludge has accumulated in the 1 00 K Basins as a result of fuel oxidation and a slight amount of general debris being deposited, by settling, in the basin water. The ultimate intent in removing the sludge and fuel is to eliminate the environmental risk posed by storing fuel at the K Basins. The task for this project is to disposition specific constituents of sludge (metallic fuel) to produce a product stream through a pretreatment process that will meet the requirements, including a final particle size acceptable to the Tank Waste Remediation System (TWRS). The purpose of this task is to develop a preconceptual design package for the K Basin sludge pretreatment system. The process equipment/system is at a preconceptual stage, as shown in sketch ES-SNF-01 , while a more refined process system and material/energy balances are ongoing (all sketches are shown in Appendix C). Thus, the overall process and 0535 associated equipment have been conservatively selected and sized, respectively, to establish the cost basis and equipment layout as shown in sketches ES- SNF-02 through 08

  7. Estimating tectonic history through basin simulation-enhanced seismic inversion: Geoinformatics for sedimentary basins

    Science.gov (United States)

    Tandon, K.; Tuncay, K.; Hubbard, K.; Comer, J.; Ortoleva, P.

    2004-01-01

    A data assimilation approach is demonstrated whereby seismic inversion is both automated and enhanced using a comprehensive numerical sedimentary basin simulator to study the physics and chemistry of sedimentary basin processes in response to geothermal gradient in much greater detail than previously attempted. The approach not only reduces costs by integrating the basin analysis and seismic inversion activities to understand the sedimentary basin evolution with respect to geodynamic parameters-but the technique also has the potential for serving as a geoinfomatics platform for understanding various physical and chemical processes operating at different scales within a sedimentary basin. Tectonic history has a first-order effect on the physical and chemical processes that govern the evolution of sedimentary basins. We demonstrate how such tectonic parameters may be estimated by minimizing the difference between observed seismic reflection data and synthetic ones constructed from the output of a reaction, transport, mechanical (RTM) basin model. We demonstrate the method by reconstructing the geothermal gradient. As thermal history strongly affects the rate of RTM processes operating in a sedimentary basin, variations in geothermal gradient history alter the present-day fluid pressure, effective stress, porosity, fracture statistics and hydrocarbon distribution. All these properties, in turn, affect the mechanical wave velocity and sediment density profiles for a sedimentary basin. The present-day state of the sedimentary basin is imaged by reflection seismology data to a high degree of resolution, but it does not give any indication of the processes that contributed to the evolution of the basin or causes for heterogeneities within the basin that are being imaged. Using texture and fluid properties predicted by our Basin RTM simulator, we generate synthetic seismograms. Linear correlation using power spectra as an error measure and an efficient quadratic optimization technique are found to be most effective in determining the optimal value of the tectonic parameters. Preliminary 1-D studies indicate that one can determine the geothermal gradient even in the presence of observation and numerical uncertainties. The algorithm succeeds even when the synthetic data has detailed information only in a limited depth interval and has a different dominant frequency in the synthetic and observed seismograms. The methodology presented here even works when the basin input data contains only 75 per cent of the stratigraphic layering information compared with the actual basin in a limited depth interval.

  8. Permian Basin location recommendation report

    International Nuclear Information System (INIS)

    Candidate study areas are screened from the Palo Duro and Dalhart Basin areas using data obtained from studies to date and criteria and specifications that consider: rock geometry; rock characteristics; human intrusion potential; surface characteristics; and environmental and socioeconomic conditions. Two preferred locations are recommended from among these areas for additional characterization to identify potential National Waste Terminal Storage (NWTS) salt repository sites. One location, in northeastern Deaf Smith County and southeastern Oldham County, is underlain by two salt units that meet the adopted screening specifications. The other location, in northcentral Swisher County, is underlain by one salt unit that meets the adopted screening specifications. Both locations have several favorable features, relative to surrounding areas, and no obviously undesirable characteristics. Both lie wholly on the Southern High Plains surface, are in relatively sparsely populated areas, contain no unique land use conflicts, and comprise large enough geographic areas to provide flexibility in site selection. Data gathered to date indicate that these locations contain salt units sufficient in thickness and in depth for the safe construction and operation of the underground facilities under consideration. 93 references, 34 figures, 6 tables

  9. Petroleum geology of the Palo Duro Basin, Texas Panhandle

    International Nuclear Information System (INIS)

    The Palo Duro Basin, Permian Basin, Texas is an asymmetric, relatively shallow, intracratonic basin in the southern Texas Panhandle filled mostly by Mississippian, Pennsylvanian, and Permian sedimentary rocks. Although deeper and prolific prolific petroleum-producing basins adjoin it on the north (Anadarko Basin), south (Midland Basin), and east (Hardeman Basin), the Palo Duro Basin has produced remarkably small amounts of oil and gas to date. This is all the more noteworthy because the sedimentary sequence and rock types of the basin are similar to those of the adjacent basins. Analyses of the stratigraphic succession and structural configuration of the Palo Duro Basin suggest that adequate reservoir rocks, top-seals, and geologic structures are present. Most of the structures formed early enough to have trapped hydrocarbons if they were migrating in the rock column. Although additional work is under way to properly address the question of the petroleum source rocks, generation, and migration, the general absence of production in the basin may relate to an overall deficiency in hydrocarbon generation within the basin. Geologic information in this report will form part of the basis for further analysis and conclusions on hydrocarbon potential in the Palo Duro Basin

  10. Groundwater recharge history and hydrogeochemical evolution in the Minqin Basin, North West China

    International Nuclear Information System (INIS)

    The Minqin Basin is a type area for examining stress on groundwater resources in the Gobi Desert, and has been investigated here using a combination of isotopic, noble gas and chemical indicators. The basin is composed of clastic sediments of widely differing grain size and during the past half century over 10 000 boreholes have been drilled with a groundwater decline of around 1 m a-1. Modern diffuse recharge is unlikely to exceed 3 mm a-1, as determined using unsaturated zone profiles and Cl- mass balance. A small component of modern (3H-3He data, probably from irrigation returns. A clear distinction is found between modern waters with median ? 18O values of 6.5 ± 0.5 per mille and most groundwaters in the basin with more depleted isotopic signatures. Radiocarbon values as pmc range from 0.6% to 85% modern, but it is difficult to assign absolute ages to these, although a value of 20% modern C probably represents the late Pleistocene to Holocene transition. The ? 13C compositions remain near-constant throughout the basin (median value of -8.1 per mille ? 13C) and indicate that carbonate reactions are unimportant and also that little reaction takes place. There is a smooth decrease in 14C activity accompanied by a parallel increase in 4He accumulations from S-N across the basin, which define the occurrence of a regional flow system. Noble gas temperatures indicate recharge temperatures of about 5.6 deg. C for late Pleistocene samples, which is some 2-3 deg. C cooler than the modern mean annual air temperature and the recharge temperature obtained from several Holocene samples. Groundwaters in the Minqin Basin have salinities generally below 1 g/L and are aerobic, containing low Fe but elevated concentrations of U, Cr and Se (mean values of 27.5, 5.8 and 5.3 ?g L-1, respectively). Nitrate is present at baseline concentrations of around 2 mg L-1 but there is little evidence of impact of high NO3 from irrigation returns. Strontium isotope and major ion ratios suggest that silicate reactions predominate in the aquifer. The results have important implications for groundwater management in the Minqin and other water-stressed basins in NW China - a region so far destined for rapid development. The large proportion of the water being used at present is in effect being mined and significant changes are urgently needed in water use strategy

  11. Geochemistry of Neoproterozoic shales of the Rabanpalli Formation, Bhima Basin, Northern Karnataka, southern India: implications for provenance and paleoredox conditions / Geoquímica de pizarras neoproterozoicas de la Formación Rabanpalli, cuenca Bhima, Karnataka norte, sur de la India: implicaciones para la proveniencia y las condiciones de paleoredox

    Scientific Electronic Library Online (English)

    Ramasamy, Nagarajan; Jayagopal, Madhavaraju; Raghavendra, Nagendra; John Selvamony, Armstrong-Altrin; Jacques, Moutte.

    2007-08-01

    Full Text Available La Formación Rabanpalli incluye dos tipos de pizarras: grises y calcáreas. Esas pizarras fueron analizadas por elementos mayores y traza para establecer las características de las rocas fuente y las condiciones de paleo-oxigenación. Las pizarras grises tienen concentraciones más altas de SiO2, Al2O3 [...] , Fe2O3, K2O, Zr, Th, U, V, Cr, La, Ce, e Y que las pizarras calcáreas, mientras que las pizarras calcáreas están enriquecidas en CaO, Mn, Sr, Ba, Cu y Zn, lo cual indica una mayor abundancia de fases carbonatadas en las pizarras calcáreas. La correlación positiva de K2O con otros elementos y la abundancia de Al2O3, Ba, Th y Rb sugieren que esos elementos están principalmente controlados por los minerales arcillosos dominantes. Las comparación de las relaciones La/Sc, Th/Sc, Th/Co, Th/Cr y Cr/Th de las pizarras con las relaciones que exhiben los sedimentos derivados de rocas básicas y félsicas (fracción fina), la corteza continental superior y la lutita australiana postarqueana (post-Archean Australian average shale, PAAS) reveló que esas relaciones se encuentran en el rango de las rocas félsicas. Un gráfico de La/Sc vs. Th/Co también sugiere una naturaleza félsica para las rocas fuente. Las pizarras presentan patrones ligeramente enriquecidos en tierras raras ligeras y un patrón plano para las tierras raras pesadas, así como anomalías negativas de Eu; estos patrones son similares a los granitoides del cratón Dharwar sugiriendo que este cratón arqueano aportó los sedimentos a la cuenca Bhima. Parámetros geoquímicos como U, U autígeno, y las relaciones U/Th, V/Cr, Ni/Co y Cu/Zn indican que las pizarras fueron depositadas en un ambiente oxidante. Abstract in english The Rabanpalli Formation exhibits two types of shales, viz. grey and calcareous shales. These shales (grey and calcareous) have been analysed for major, trace, and rare earth elements to find out their source rocks characteristics and paleo-oxygenation conditions. The grey shales have higher concent [...] ration of SiO2, Al2O3, Fe2O3, K2O, Zr, Th, U, V, Cr, La, Ce, and Y than calcareous shales, whereas calcareous shales are enriched in CaO, Mn, Sr, Ba, Cu, and Zn, which indicate that the carbonate phase minerals are higher in calcareous shales. The positive correlation of K2O with other elements, and abundance of Al2O3, Ba, Th, and Rb suggest that these elements are primarily controlled by the dominant clay minerals. La/Sc, Th/Sc, Th/Co, Th/Cr, and Cr/Th ratios of shales were compared with those of sediments derived from felsic and basic rocks (fine fraction), upper continental crust (UCC) and post-Archean Australian average shale (PAAS) ratios, which reveal that these ratios are within the range of felsic rocks. The La/Sc vs. Th/Co plot also suggests the felsic nature of the source rocks. The shales show slightly light rare earth element (LREE) enriched and flat heavy rare earth element (HREE) patterns with negative Eu anomaly, and are similar to the granitoids from Dharwar Craton, which suggest that the Archean Dharwar Craton contributed the sediments to the Bhima basin. The geochemical parameters such as U, authigenic U, U/Th, V/Cr, Ni/Co, and Cu/Zn ratios indicate that these shales were deposited under oxic environment.

  12. Resultados del pozo San Lorenzo Tezonco y sus implicaciones en el entendimiento de la hidrogeología regional de la cuenca de México / Results from the San Lorenzo Tezonco borehole and their implications for the understanding of the basin of Mexico regional hydrogeology

    Scientific Electronic Library Online (English)

    Eric, Morales-Casique; Oscar A., Escolero; José L., Arce.

    2014-04-01

    Full Text Available Los resultados del pozo exploratorio San Lorenzo Tezonco con 2008 m de profundidad permiten investigar las características hidrogeológicas de las formaciones profundas en la cuenca de México. Con base en el análisis de los registros litológico y eléctrico se definen cinco unidades hidrogeológicas: a [...] ) de 0 a 70 m acuitardo compuesto por sedimentos lacustres arcillosos; b) de 70 a 500 m acuífero superior compuesto por materiales vulcanoclásticos; c) de 500 a 750 m acuífero en lavas y flujos piroclásticos (con una intercalación lacustre de 590 a 604 m); d) de 750 a 1140 m acuitardo compuesto por ignimbritas, arcillas y materiales vulcanoclásticos con resistividades eléctricas de entre 2 y 20 ?m; e) de 1140 a 2008 m acuífero en rocas volcánicas con intercalaciones de acuitardos de baja resistividad eléctrica (de entre 2 y 10 ?m) y que exhibieron poca o nula penetración del lodo de perforación inferida del registro eléctrico. Estas cinco unidades hidrogeológicas son heterogéneas en su composición y parámetros hidrogeológicos tal como se deduce del registro eléctrico. Con base en una prueba de aforo se calculó la conductividad hidráulica promedio y el almacenamiento específico promedio de la quinta unidad hidrogeológica. Puesto que únicamente se contó con muestras de recorte, la incertidumbre en el corte litológico es alta y para reducirla será necesario obtener núcleos en exploraciones futuras. Adicionalmente se analizan las características químicas e isotópicas del agua proveniente del intervalo de 1176 a 2008 m (que es la longitud ranurada en el pozo). La composición isotópica de ?18O = -67.3 ‰ y ?D = -9.44 ‰ sugiere un origen por infiltración de la precipitación; la datación del agua por carbono 14 (corregida por carbono 13) resultó en 14,237±265 años de tiempo de residencia, mientras que la presencia de microfracturas rellenas de calcita y yeso en muestras de 1800 a 1920 m de profundidad y valores de ?13C = -5.8‰ sugieren circulación a través de rocas carbonatadas, que no fueron encontradas en el pozo San Lorenzo Tezonco pero que se infiere se encuentran a mayor profundidad con base en los resultados de los pozos Mixhuca y Tulyehualco. Abstract in english Results from the 2008 m deep San Lorenzo Tezonco exploratory borehole allow investigating the hydrogeological characteristics of deep formations in the basin of Mexico. Based on the analysis of the lithology and well logs five hydrogeologic units are defined: a) from 0 to 70 m aquitard composed by c [...] lay-rich lacustrine sediments; b) from 70 to 500 m upper aquifer composed by volcanoclastic materials; c) from 500 to 750 m aquifer composed by lava andpyroclastic flows (with a lacustrine layer embeddedfrom 590 to 604 m); d) from 750 to 1140 m aquitard composed by ignimbrites, clay and volcanoclastic materials, which exhibited electric resistivity ranging from 2 to 20 ?m; e) from 1140 to 2008 m aquifer composed by volcanic rocks interbedded with aquitard layers of electric resistivity ranging from 2 to 10 ?m and which exhibited almost no drilling mud invasion as shown by the electric log. These five hydrogeologic units are highly heterogeneous in their composition and their hydrogeologic parameters as inferred from the electric well log. Average hydraulic conductivity and specific storage were computed for the fifth hydrogeologic unit from a step drawdown test. Since only cuttings were available for analysis, the lithology record obtained is uncertain; to reduce this uncertainty it will be necessary to obtain cores in future explorations. In addition, the chemical and isotopic characteristics of water from 1176 to 2008 m (which is the screened length of the well) were analyzed. The isotopic composition (S18O = -67.3 ‰ and SD = -9.44 ‰) suggests an origin by infiltration of precipitation. Carbon 14 dating (corrected by carbon 13) resulted in a residence time of 14,237±265 years. Microfractures filled with calcite and gypsum observed in cuttings from 1800 to 1920 m and values of

  13. Preliminary discussion on relationship between deep-basin gas and uranium mineralization in Ordos basin

    International Nuclear Information System (INIS)

    Deep-basin gas is a kind of non-traditional natural gas deposit. The deep-basin gas in Ordos basin is closely associated with uranium mineralization. Upper Paleozoic in the basement of the basin represents both gas-sourced and uranium-sourced beds and uranium in Paleozoic strata is easily leachable. The squeezed water (i.e. deep-bed water) formed during the diagenetic process of uranium-sourced bed was rapidly heated and pressed making the uranium solubility in it greatly increased. It was just the peak-period of gas generation in the basin, and gas pressure greatly exceeded water pressure. So, the gas made deep-bed water moved and diffused upwards along faults. Because of the complicated gas-water geochemical barrier formed by the involvement of surface water, the precipitation of uranium occurred in overlying aquifers to form uranium deposit. This paper has summarized prospecting criteria of such uranium deposit as well

  14. Hydrogeology of the West Siberian Basin

    International Nuclear Information System (INIS)

    Nuclear fuel cycle activities of the former Soviet Union (FSU) have resulted in significant contamination of the environment in western Siberia. The radioactive releases to surface waters and the surficial environment from the Mayak site are the largest known in the world. However, they are dwarfed by the amounts of liquid wastes injected into the subsurface at Tomsk and Krasnoyarsk since the early 1960s. This paper provides the status of efforts by Pacific Northwest National Laboratory to quantify the regional hydrogeologic context for potential contaminant migration from areas in western Siberia. The West Siberian Basin is the largest platformal basin and region of low relief on earth. Ground water in the West Siberian Basin is contained in a single geologic structure (i.e., a single basin). Hydrogeologic cross sections indicate that freshwater wedges are present in both unconfined and confined aquifers (as well as in Paleozoic rocks) in the highland regions that rim the basin. The authors developed a 13-layer, finite-element computer model of the West Siberian Basin primarily based on GIS integration of data from geologic studies. The top of the hydrologic system was assumed to coincide with a water table derived from smoothed topography and surface-water occurrences; precipitation supplied the water, and the topographic gradient of the water table supplied the driving force for ground-water flow. The general directions of calculated ground-water flow suggest that calculated ground-water flow suggest that (1) the major rivers act as discharge areas, with upwelling below the rivers extending down into the basement rocks; and (2) ground-water divides that penetrate the entire thickness of the model are evident between the major rivers. Their results suggest that contaminants entering the confined aquifer system may eventually migrate to the surface, discharging within major rivers, rather than remaining confined for long travel distances within the basin sedimentsNuclear fuel cycle activities of the former Soviet Union (FSU) have resulted in significant contamination of the environment in western Siberia. The radioactive releases to surface waters and the surficial environment from the Mayak site are the largest known in the world. However, they are dwarfed by the amounts of liquid wastes injected into the subsurface at Tomsk and Krasnoyarsk since the early 1960s. This paper provides the status of efforts by Pacific Northwest National Laboratory to quantify the regional hydrogeologic context for potential contaminant migration from areas in western Siberia. The West Siberian Basin is the largest platformal basin and region of low relief on earth. Ground water in the West Siberian Basin is contained in a single geologic structure (i.e., a single basin). Hydrogeologic cross sections indicate that freshwater wedges are present in both unconfined and confined aquifers (as well as in Paleozoic rocks) in the highland regions that rim the basin. The authors developed a 13-layer, finite-el