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Sample records for williston basin implications

  1. Map service: Petroleum Assessment of the Williston Basin (williston_2008)

    U.S. Geological Survey, Department of the Interior — Map showing assessment unit and total petroleum system boundaries for Williston Basin petroleum assessment. Intented to be used with Energy Program interactive...

  2. Diagenesis and fracture development in the Bakken Formation, Williston Basin; implications for reservoir quality in the middle member

    Science.gov (United States)

    Pitman, Janet K.; Price, Leigh C.; LeFever, Julie A.

    2001-01-01

    The middle member of the Bakken Formation is an attractive petroleum exploration target in the deeper part of the Williston Basin because it is favorably positioned with respect to source and seal units. Progressive rates of burial and minor uplift and erosion of this member led to a stable thermal regime and, consequently, minor variations in diagenesis across much of the basin. The simple diagenetic history recorded in sandstones and siltstones in the middle member can, in part, be attributed to the closed, low-permeability nature of the Bakken petroleum system during most of its burial history. Most diagenesis ceased in the middle member when oil entered the sandstones and siltstones in the Late Cretaceous. Most oil in the Bakken Formation resides in open, horizontal fractures in the middle member. Core analysis reveals that sandstones and siltstones associated with thick mature shales typically have a greater density of fractures than sandstones and siltstones associated with thin mature shales. Fractures were caused by superlithostatic pressures that formed in response to increased fluid volumes in the source rocks during hydrocarbon generation

  3. Integrierte Geochemie- und Beckenmodellierungsstudie der Bakken Formation, Williston Basin

    OpenAIRE

    Kuhn, Philipp Peter

    2013-01-01

    The self-contained Bakken Formation petroleum system of the Williston Basin in central North America is one of the currently most active and successful low permeability hydrocarbon plays in the world. In contrast to conventional hydrocarbon plays where selected locations or fields are drained by a limited number of wells, the low permeability reservoir of the Bakken Formation has to be stimulated to enable production. This leads to a resource play appearance of the system in which every area ...

  4. Thickness of the glacial aquifer system in the Williston structural basin

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

  5. Proceedings of the 13. Williston Basin petroleum conference

    International Nuclear Information System (INIS)

    This conference provided a forum for the exchange of ideas and technologies that have resulted in more efficient oil drilling and production methods in the Williston Basin, which plays a significant role in the economies of Saskatchewan, Manitoba, North and South Dakota and Montana. Various enhanced recovery methods were discussed, as well as new surveying techniques. Well construction, new technologies in injection, swelling packer and artificial lift systems were reviewed. Various fracturing options were examined. Updates on oil and gas activities were presented, along with new policies and legislation aimed at increasing productivity in the oil and gas industry. Thirty-nine papers were presented at this conference, 17 of which have been catalogued separately for inclusion in this database. (author)

  6. Geomechanics and elastic anisotropy of the Bakken Formation, Williston Basin

    Science.gov (United States)

    Ostadhassan, Mehdi

    Many of the earth's rocks exhibit anisotropic characteristics. Anisotropy is particularly common in many sedimentary rocks, such as shales. Anisotropy is defined as the spatial alignment of mineral grains, layers, fractures and stresses which causes elastic wave velocity and other elastic properties to vary with direction. There are two types of anisotropy: intrinsic and stress-induced. Intrinsic anisotropy is caused by beddings, microstructures or aligned fractures formed during deposition. Stress-induced anisotropy is caused by strain associated with external stresses. Intrinsic anisotropy originates in the absence of external stresses, while stress-induced anisotropy results from tectonic and overburden stresses. The style of earth material alignment causes two simplified, but convenient models of anisotropy: vertically transverse isotropy (VTI), like shale, and horizontally transverse isotropy (HTI), like vertically fractured medium. These models have been used to describe how physical properties of rock vary in a medium. Identifying the anisotropy in a formation is important in reservoir characterization seismic data processing and oil-field development. Deep shales are the most abundant yet least characterized sedimentary rocks in the Williston Basin of North Dakota. They are significant sources of hydrocarbon unconventional resources in this basin. This dissertation aims to fulfill an investigation of anisotropy in this rock type in several different facets through exploiting of field data. I seek to generate key information for better interplay of field in-situ stress and the existing natural fracture systems for the purpose of drilling, well completion, perforating, hydraulic fracturing and defining reservoir properties. In this study advanced sonic logging data has been processed and interpreted to calculate three independent shear moduli. These parameters then will be used to estimate Thomsen (1986) anisotropy parameters, elastic stiffness coefficients and principal stresses of deep shales in the Williston Basin. The parameters then will be used to generate shear radial profiles and slowness-frequency plots analyze formation anisotropy type and origin as well as reservoir quality. The next step will be to evaluate direction and magnitude of the minimum and maximum anisotropic principal horizontal stresses as the governing element in geomechanical modeling. I will analyze wellbore stability and predict wellbore behavior under stress alteration caused by drilling. Elastic anisotropy of the formation will be included in the 3-D numerical models. In addition the effects of local geological features on the mode of anisotropy both in the far-field and around the borehole to get an in-depth insight of the fractures will be studied. Finally, by generating stress polygons for the reservoir, before and after production and pressure decline, I will try to study how reservoir depletion may cause future geological natural hazards such as faulting and induced seismic events in the region.

  7. Sulfur isotope ratios in petroleum research and exploration: Williston basin

    International Nuclear Information System (INIS)

    The three major types of crude oil in the Williston basin - the type I oils of the Winnipeg-Red River system, the type II oils of the Bakken-Madison system, and the type III oils of the Tyler-Pennsylvanian system - can be distinguished by their sulfur isotope compositions. They have characteristic delta34S values of 5.8 +- 1.2 parts per thousand (ppt), 2.8 +- 0.8 ppt, and -4.0 +- 0.7 ppt respectively. Highly mature oils have less typical values. Type II oils which have migrated over a distance of some 150 km beyond the region of generation have maintained their characteristic delta34S values even though sulfur may have been lost. This indicates little or no interaction with reservoir sulfates under normal circumstances. On the periphery of the basin, type II oils altered by water washing and biodegradation have altered delta34S values which increase from +2.9 to +9.4 ppt with the increasing degree of crude oil degradation. The Bakken shales, source of the type II oils, have delta34S distribution patterns in the reduced sulfur typical of marine sediments. The delta34S values for the type II oils match most closely the delta34S value of organic sulfur in the black bituminous shales of the lower Bakken

  8. Assessment of Undiscovered Oil Resources in the Devonian-Mississippian Bakken Formation, Williston Basin Province, Montana and North Dakota, 2008

    Science.gov (United States)

    Pollastro, Richard M.; Cook, Troy A.; Roberts, Laura N.R.; Schenk, Christopher J.; Lewan, Michael D.; Anna, Lawrence O.; Gaswirth, Stephanie B.; Lillis, Paul G.; Klett, Timothy R.; Charpentier, Ronal R.

    2008-01-01

    Using a geology-based assessment methodology, the U.S. Geological Survey estimated mean undiscovered volumes of 3.65 billion barrels of oil, 1.85 trillion cubic feet of associated/dissolved natural gas, and 148 million barrels of natural gas liquids in the Bakken Formation of the Williston Basin Province, Montana and North Dakota.

  9. Magnetic Surveys and Rock Magnetic Properties of Clinkers in the Williston Basin

    Science.gov (United States)

    Sternberg, R. S.

    2009-12-01

    Clinkers are pyrometamorphic rocks formed when sedimentary rocks are baked by burning of underlying coal seams. Scoriaceous and vesicular textures can be produced. In the Williston Basin, the Tertiary coals are of lignite and sub-bituminous rank. Burning took place upon erosion and exposure of the coal seams during the Quaternary; the coals were ignited by range fires or spontaneous combustion. Magnetic anomalies over clinkers delineate coal burns and hence the coal resource. This study measured magnetic anomalies over 1,000 nT on profiles crossing clinker outcrops in Theodore Roosevelt National Park, Montana. The boundaries of the clinker zones inferred from the magnetic anomalies can differ by 100 meters from surface indications of the burning. Magnetic anomalies over other sedimentary rocks in the area are less than 10 nT. Similar anomalies over clinkers have been observed by others elsewhere in the Williston Basin as well as in New Zealand, China, and Siberia. The magnetic signatures were generated under unusual geologic conditions of low pressure, high temperature, and high oxygen fugacity. Magnetic susceptibility of clinkers were enhanced by 2-3 orders of magnitude, and a thermoremanent magnetization was acquired. There was a general correlation between susceptibility and remanence in the Williston Basin clinkers, interpreted as representing ferrimagnetic concentration. Koenigsberger ratios near 1 showed similar contributions from induced and remanent magnetization. Samples near clinker chimney vents where oxygen could more freely circulate had the highest susceptibilities and remanences. The enhanced susceptibility and remanences juxtaposed against the non-magnetic sedimentary rocks caused the large magnitude anomalies at the clinker edges. IRM acquisition showed the presence of both lower coercivity ferrimagnetic minerals and higher coercivity antiferromagnetic minerals in these rocks. Enhancement of magnetic susceptibility and remanence due to combustion metamorphism has also been noted in Southern California, Israel, New Zealand, and China. The ability of pyrometamorphic rocks to acquire a remanent magnetization makes them potentially useful for paleomagnetic studies. Zijderveld plots showed stable directions of magnetization. However, accurate recording of the paleomagnetic recording would require rocks that have not mechanically rotated since becoming magnetized, a difficult requirement due to collapse of overlying rocks when the coal seams burned out.

  10. Lithofacies and paleo-environments of the Upper Devonian and Lower Mississippian Bakken Formation, Williston Basin

    Energy Technology Data Exchange (ETDEWEB)

    Smith, M.G.; Bustin, R.M. [British Columbia Univ., Vancouver, BC (Canada). Dept. of Geological Sciences]|[British Columbia Univ., Vancouver, BC (Canada). Dept. of Oceanography

    1996-09-01

    The sedimentology of the Bakken Formation was described and a regional paleoenvironmental interpretation of conditions within the Williston Basin in Late Devonian and Early Mississippian time was presented. 385 well logs and 189 core intervals from Saskatchewan, Manitoba and North Dakota were studied. Two depositional episodes were noted. The first was the deposition of offshore muds in distal deep water more than 200 m deep. The second was the accumulation of offshore muds in water 10 to 200 m in depth. Detailed lithofacies descriptions and paleoenvironmental interpretations suggested that there were three separate occasions of sea level changes of at least 200 m during Late Devonian and Early Mississippian time. 67 refs., 1 tab., 6 figs.

  11. Paleohydrogeology of the Cretaceous sediments of the Williston Basin using stable isotopes of water

    Science.gov (United States)

    Hendry, M. Jim; Barbour, S. L.; Novakowski, K.; Wassenaar, L. I.

    2013-08-01

    Hydraulic and isotopic data collected from aquifers are routinely used to characterize hydrogeological conditions within sedimentary basins, but similar data from confining units are generally not collected despite their ability to provide insights on important water/solute transport controls. We characterized paleogroundwater flow and solute transport mechanisms across 384 m of Cretaceous shale (aquitard) in the Williston Basin, Canada, using high-resolution depth profiles of water isotopes (?18O, ?2H). Water samples were also collected from wells installed in the underlying regional sandy aquifer (Mannville Fm; 93 m thick) and from seepage inflows into potash mine shafts (to 825 m below ground). The 1-D numerical transport modeling of ?18O profiles provided insight into large-scale/long-term solute transport in both Cretaceous sediments and the basin. Despite the potential for significant advective migration during glaciations, molecular diffusion appears to be the dominant solute transport mechanism through the aquitard. Simulations suggest average vertical groundwater velocities of introduction during the Pleistocene of glaciogenic meteoric water to the aquifer underlying the shale, likely along an aquifer outcrop area east of the site or through local vertical conduits. Simulations suggest these recharge events occurred during one or more glacial periods. The isotopic profile over the upper 25 m of Pleistocene till and shale is consistent with glacial deposition and transport processes within these units over the Holocene (past 10 ka).

  12. Investigation of relationships between linears, total and hazy areas, and petroleum production in the Williston Basin: An ERTS approach

    Science.gov (United States)

    Erickson, J. M.; Street, J. S. (principal investigators); Munsell, C. J.; Obrien, D. E.

    1975-01-01

    The author has identified the following significant results. ERTS-1 imagery in a variety of formats was used to locate linear, tonal, and hazy features and to relate them to areas of hydrocarbon production in the Williston Basin of North Dakota, eastern Montana, and northern South Dakota. Derivative maps of rectilinear, curvilinear, tonal, and hazy features were made using standard laboratory techniques. Mapping of rectilinears on both bands 5 and 7 over the entire region indicated the presence of a northeast-southwest and a northwest-southeast regional trend which is indicative of the bedrock fracture pattern in the basin. Curved lines generally bound areas of unique tone, maps of tonal patterns repeat many of the boundaries seen on curvilinear maps. Tones were best analyzed on spring and fall imagery in the Williston Basin. It is postulated that hazy areas are caused by atmospheric phenomena. The ability to use ERTS imagery as an exploration tool was examined where petroleum and gas are presently produced (Bottineau Field, Nesson and Antelope anticlines, Redwing Creek, and Cedar Creek anticline). It is determined that some tonal and linear features coincide with location of present production in Redwing and Cedar Creeks. In the remaining cases, targets could not be sufficiently well defined to justify this method.

  13. Long-term solute transport through thick Cretaceous shale in the Williston Basin Canada using naturally-occurring tracer profiles

    International Nuclear Information System (INIS)

    Document available in abstract form only. The hydrogeologic evolution of sedimentary basins is generally determined from hydraulic and chemical data collected from aquifers. Hydraulic and chemical data from aquitards, which constitute a much greater volume of basins than aquifers and provide important controls on water and solute transport in the basins, are generally not collected nor studied. In this study we characterized the paleo-groundwater flow and solute transport controls through a vertical section of Cretaceous sediments in the Williston Basin, Canada located near Esterhazy, Saskatchewan. It consists of 384 m of thick argillaceous sediment (aquitard) overlying 93 m of heterogeneous calcareous silt, shale and sandstone (Mannville Fm.; aquifer). Paleo-hydrologic conditions were determined by interpreting high-resolution depth profiles of natural tracers of water isotopes (?18O and (?2H) and Cl- measured on (1) continuous core samples through the aquitard, upper aquifer, and thin Quaternary sediments, (2) water samples collected from monitoring wells installed in the aquifer and the Quaternary sediments, and (3) water samples collected from mine shaft inflows to 900 m below ground. 1D numerical transport modeling reproduced the measured profiles and yielded valuable information on the large-scale and long-term transport behavior in both the Cretaceous aquitard and the Basin. In the modeling, the shapes of the tracer profiles was explaineapes of the tracer profiles was explained by diffusion with paleo-events identified from the modeling including the introduction of fresher water into the aquifer possibly from the onset of glaciation (activation of the lower boundary) about 1 Ma ago and the impact of the most recent deglaciation about 10 ka ago (activation of the upper boundary). These findings show that the hydrogeologic conditions in deep, extensive basins, such as the Williston Basin, cannot be assumed to be static over geologic time. (authors)

  14. Geology of the Williston basin, North Dakota, Montana, and South Dakota, with reference to subsurface disposal of radioactive wastes

    Science.gov (United States)

    Sandberg, C.A.

    1962-01-01

    The southern Williston basin, which underlies about 110,000 square miles #n North Dakota, South Dakota, and eastern Montana, is part of a large structural and sedimentary basin. Its surface is a flat to gently rolling plain, standing about 1,500 to 3,500 feet above sea level and locally studded by a few high buttes. The sedimentary sequence that fills the basin has a maximum thickness of about 16,700 feet and rests on Precambrian metamorphic rocks at depths of 500 to 13,900 feet below sea level. It contains rocks of every geologic system, from Cambrian to Quaternary. Rocks of Middle Cambrian through Middle Ordovician age are largely shale and sandstone, as much as 1,200 feet thick; rocks of Late Ordovician through Pennsylvanian age are largely limestone and dolomite, as much as 7,500 feet thick; and rocks of Permian through Tertiary age are predominantly shale and siltstone, as much as 8,000 feet thick. Pleistocene glacial drift mantles the northern and eastern parts of the area. Rocks of the Williston basin are gently folded and regional dips are 1? or less from the margins to the basin center. Dips on the flanks of the major anticlinal folds, the Nesson and cedar Creek anticlines and the Poplar and Bowdoin domes, generally are about 1? to 3? except on the steep west limb of the Cedar Creek anticline. The basin was shaped by Laramide orogeny during latest Cretaceous and early Tertiary time. Most of the present structural features, however, were initiated during the Precambrian and reactivated by several subsequent orogenies, of which the latest was the Laramide. The most important mineral resource of the area is oil, which is produced predominantly from the Paleozoic carbonate sequence and largely on three of the major anticlinal folds, and lignite, which is present near the surface in Paleocene rocks. The subsurface disposal of radioactive wastes at some places in the Williston basin appears to be geographically and geologically feasible. Many sites, at which large quantities of wastes might be injected with minimal danger of contamination of fresh-water aquifers and-oil-producing strata, are available.. The strata and types of reservoirs that deserve primary consideration for waste disposal are the Winnipeg Formation of Middle Ordovician age as a deep salaquifer, the Permian to Jurassic salt beds as moderately deep-units in which solution cavities might be created for storage, the thick Upper Cretaceous shale beds as shallow hydraulically fractured shale reservoirs, and the Newcastle Sandstone of Early Cretaceous age as a shallow shale-enclosed sandstone reservoir.

  15. Assessment of Undiscovered Technically Recoverable Oil and Gas Resources of the Bakken Formation, Williston Basin, Montana and North Dakota, 2008

    Science.gov (United States)

    Pollastro, R.M.; Roberts, L.N.R.; Cook, T.A.; Lewan, M.D.

    2008-01-01

    The U.S. Geological Survey (USGS) has completed an assessment of the undiscovered oil and associated gas resources of the Upper Devonian to Lower Mississippian Bakken Formation in the U.S. portion of the Williston Basin of Montana and North Dakota and within the Williston Basin Province. The assessment is based on geologic elements of a total petroleum system (TPS), which include (1) source-rock distribution, thickness, organic richness, maturation, petroleum generation, and migration; (2) reservoir-rock type (conventional or continuous), distribution, and quality; and (3) character of traps and time of formation with respect to petroleum generation and migration. Framework studies in stratigraphy and structural geology and modeling of petroleum geochemistry, combined with historical exploration and production analyses, were used to estimate the undiscovered, technically recoverable oil resource of the Bakken Formation. Using this framework, the USGS defined a Bakken-Lodgepole TPS and seven assessment units (AU) within the system. For the Bakken Formation, the undiscovered oil and associated gas resources were quantitatively estimated for six of these AUs.

  16. Geochemical analysis and familial association of Red River and Winnipeg reservoired oils of the Williston Basin, Canada

    Energy Technology Data Exchange (ETDEWEB)

    Smith, M.; Bend, S. [Regina Univ., Saskatchewan (Canada). Dept. of Geology

    2004-04-01

    Light oils reservoired in the Lower Ordovician Winnipeg Formation, Williston Basin, have a unique geochemical signature separating them from previously recognized oil families, most importantly they are geochemically distinct from the stratigraphically adjacent Upper Ordovician Red River Formation oils. Winnipeg oils are characterized in the gasoline fraction by very high paraffin indices (4-16) and variations in C{sub 7} parameters. The saturate fraction is distinguished by a high abundance of C{sub 20+} n-alkanes, low carbon preference index and low amounts of pristane and phytane. Sterane biomarkers show a predominance of C{sub 27}>C{sub 28}{approx}C{sub 29} suggesting an algal source different from that contributing to Red River oils. In addition, the terpane biomarkers of Winnipeg oils show a high abundance of rearranged hopanes including an unknown C{sub 30} compound labelled UC30 and 17{alpha} (H) C{sub 30}-diahopanes (C*{sub 30}), Moreover, these oils have unambiguous amounts of 18{alpha} (H)-30-norneohopanes (C{sub 29}Ts) which are in low abundance in Red River Formation oils. Geochemical analysis of Lower Ordovician Winnipeg Formation reservoired oils from the Williston Basin suggests that an additional hydrocarbon source, not yet defined, may exist. (Author)

  17. Assessment of undiscovered oil resources in the Bakken and Three Forks Formations, Williston Basin Province, Montana, North Dakota, and South Dakota, 2013

    Science.gov (United States)

    Gaswirth, Stephanie B.; Marra, Kristen R.; Cook, Troy A.; Charpentier, Ronald R.; Gautier, Donald L.; Higley, Debra K.; Klett, Timothy R.; Lewan, Michael D.; Lillis, Paul G.; Schenk, Christopher J.; Tennyson, Marilyn E.; Whidden, Katherine J.

    2013-01-01

    Using a geology-based assessment methodology, the U.S. Geological Survey estimated mean undiscovered volumes of 7.4 billion barrels of oil, 6.7 trillion cubic feet of associated/dissolved natural gas, and 0.53 billion barrels of natural gas liquids in the Bakken and Three Forks Formations in the Williston Basin Province of Montana, North Dakota, and South Dakota.

  18. Comparing vertical profiles of natural tracers in the Williston Basin to estimate the onset of deep aquifer activation

    Science.gov (United States)

    Hendry, M. Jim; Harrington, Glenn A.

    2014-08-01

    Comparing high-resolution depth profiles of different naturally occurring environmental tracers in aquitards should yield consistent and perhaps complementary information about solute transport mechanisms and the timing of major hydrogeological and climatological events. This study evaluated whether deep, continuous profiles of aquitard pore water chloride concentration could provide further insight into the paleohydrology of the Williston Basin, Canada, than possible using high-resolution depth profiles of stable H/O isotopes of water (?18O, ?2H). Pore water samples were obtained from extracts of cores taken over 392 m of the thick Cretaceous shale aquitard. Water samples were also collected from wells installed in the underlying regional sandy aquifer (Mannville Group; 93 m thick) and from seepage inflows into potash mine shafts (to 825 m below ground). Numerical modeling of the 1-D vertical Cl- profile supported diffusion dominated solute transport in the shales. The modeling also showed a similar time frame for development of the Cl- profile prior to activation of the aquifer as determined from the ?18O profile (20-25 Ma); however, it provided a significantly longer and potentially better-constrained time frame for evolution of the profile during the activation phase of the aquifer (0.5-1 Ma). The dominant paleoevent reflected in present-day profiles of both tracers is the introduction of glaciogenic meteoric water to the Mannville aquifer underlying the shale during the Pleistocene. The source area of this water remains to be determined.

  19. 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.

  20. A resource evaluation of the Bakken Formation (Upper Devonian and Lower Mississippian) continuous oil accumulation, Williston Basin, North Dakota and Montana

    Science.gov (United States)

    Schmoker, J.W.

    1996-01-01

    The Upper Devonian and Lower Mississippian Bakken Formation in the United States portion of the Williston Basin is both the source and the reservoir for a continuous oil accumulation - in effect a single very large field - underlying approximately 17,800 mi2 (46,100 km2) of North Dakota and Montana. Within this area, the Bakken Formation continuous oil accumulation is not significantly influenced by the water column and cannot be analyzed in terms of conventional, discrete fields. Rather, the continuous accumulation can be envisioned as a collection of oil-charged cells, virtually all of which are capable of producing some oil, but which vary significantly in their production characteristics. Better wellperformance statistics are linked regionally to higher levels of thermal maturity and to lower levels of reservoir heterogeneity. Although portions of the Bakken Formation continuous oil accumulation have reached a mature stage of development, the accumulation as a whole is far from depleted.

  1. 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.

  2. Input-form data for the U.S. Geological Survey assessment of the Devonian and Mississippian Bakken and Devonian Three Forks Formations of the U.S. Williston Basin Province, 2013

    Science.gov (United States)

    U.S. Geological Survey Bakken-Three Forks Assessment Team; Gaswirth, Stephanie B.; Marra, Kristen R.; Cook, Troy A.; Charpentier, Ronald R.; Gautier, Donald L.; Higley, Debra K.; Klett, Timothy R.; Lewan, Michael D.; Lillis, Paul G.; Schenk, Christopher J.; Tennyson, Marilyn E.; Whidden, Katherine J.

    2013-01-01

    In 2013, the U.S. Geological Survey assessed the technically recoverable oil and gas resources of the Bakken and Three Forks Formations of the U.S. portion of the Williston Basin. The Bakken and Three Forks Formations were assessed as continuous and hypothetical conventional oil accumulations using a methodology similar to that used in the assessment of other continuous- and conventional-type assessment units throughout the United States. The purpose of this report is to provide supplemental documentation and information used in the Bakken-Three Forks assessment.

  3. 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.

  4. Traces in the dark: sedimentary processes and facies gradients in the upper shale member of the Upper Devonian-Lower Mississippian Bakken Formation, Williston Basin, North Dakota, U.S.A.

    Science.gov (United States)

    Egenhoff, Sven O.; Fishman, Neil S.

    2013-01-01

    Black, organic-rich rocks of the upper shale member of the Upper Devonian–Lower Mississippian Bakken Formation, a world-class petroleum source rock in the Williston Basin of the United States and Canada, contain a diverse suite of mudstone lithofacies that were deposited in distinct facies belts. The succession consists of three discrete facies associations (FAs). These comprise: 1) siliceous mudstones; 2) quartz- and carbonate-bearing, laminated mudstones; and 3) macrofossil-debris-bearing massive mudstones. These FAs were deposited in three facies belts that reflect proximal to distal relationships in this mudstone system. The macrofossil-debris-bearing massive mudstones (FA 3) occur in the proximal facies belt and contain erosion surfaces, some with overlying conodont and phosphate–lithoclast lag deposits, mudstones with abundant millimeter-scale siltstone laminae showing irregular lateral thickness changes, and shell debris. In the medial facies belt, quartz- and carbonate-bearing, laminated mudstones dominate, exhibiting sub-millimeter-thick siltstone layers with variable lateral thicknesses and localized mudstone ripples. In the distal siliceous mudstone facies belt, radiolarites, radiolarian-bearing mudstones, and quartz- and carbonate-bearing, laminated mudstones dominate. Overall, total organic carbon (TOC) contents range between about 3 and 10 wt %, with a general proximal to distal decrease in TOC content. Abundant evidence of bioturbation exists in all FAs, and the lithological and TOC variations are paralleled by changes in burrowing style and trace-fossil abundance. While two horizontal traces and two types of fecal strings are recognized in the proximal facies belt, only a single horizontal trace fossil and one type of fecal string characterize mudstones in the distal facies belt. Radiolarites intercalated into the most distal mudstones are devoid of traces and fecal strings. Bedload transport processes, likely caused by storm-induced turbidity currents, were active across all facies belts. Suspended sediment settling from near the ocean surface, however, most likely played a role in the deposition of some of the mudstones, and was probably responsible for deposition of the radiolarites. The distribution pattern of high-TOC sediments in proximal and lower-TOC deposits in some distal facies is interpreted as a function of higher accumulation rates during radiolarian depositional events leading to a decrease in suspension-derived organic carbon in radiolarite laminae. The presence of burrows in all FAs and nearly all facies in the upper Bakken shale member indicates that dysoxic conditions prevailed during its deposition. This study shows that in intracratonic high-TOC mudstone successions such as the upper Bakken shale member bed-load processes most likely dominated sedimentation, and conditions promoted a thriving infaunal benthic community. As such, deposition of the upper Bakken shale member through dynamic processes in an overall dysoxic environment represents an alternative to conventional anoxic depositional models for world-class source rocks.

  5. 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

  6. 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.

  7. 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.

  8. Stratigraphy of the Caloris basin, Mercury: Implications for volcanic history and basin impact melt

    Science.gov (United States)

    Ernst, Carolyn M.; Denevi, Brett W.; Barnouin, Olivier S.; Klimczak, Christian; Chabot, Nancy L.; Head, James W.; Murchie, Scott L.; Neumann, Gregory A.; Prockter, Louise M.; Robinson, Mark S.; Solomon, Sean C.; Watters, Thomas R.

    2015-04-01

    Caloris basin, Mercury's youngest large impact basin, is filled by volcanic plains that are spectrally distinct from surrounding material. Post-plains impact craters of a variety of sizes populate the basin interior, and the spectra of the material they have excavated enable the thickness of the volcanic fill to be estimated and reveal the nature of the subsurface. The thickness of the interior volcanic plains is consistently at least 2.5 km, reaching 3.5 km in places, with thinner fill toward the edge of the basin. No systematic variations in fill thickness are observed with long-wavelength topography or azimuth. The lack of correlation between plains thickness and variations in elevation at large horizontal scales within the basin indicates that plains emplacement must have predated most, if not all, of the changes in long-wavelength topography that affected the basin. There are no embayed or unambiguously buried (ghost) craters with diameters greater than 10 km in the Caloris interior plains. The absence of such ghost craters indicates that one or more of the following scenarios must hold: the plains are sufficiently thick to have buried all evidence of craters that formed between the Caloris impact event and the emplacement of the plains; the plains were emplaced soon after basin formation; or the complex tectonic deformation of the basin interior has disguised wrinkle-ridge rings localized by buried craters. That low-reflectance material (LRM) was exposed by every impact that penetrated through the surface volcanic plains provides a means to explore near-surface stratigraphy. If all occurrences of LRM are derived from a single layer, the subsurface LRM deposit is at least 7.5-8.5 km thick and its top likely once made up the Caloris basin floor. The Caloris-forming impact would have generated a layer of impact melt 3-15 km thick; such a layer could account for the entire thickness of LRM. This material would have been derived from a combination of lower crust and upper mantle.

  9. 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)

  10. GRAIL Gravity Observations of Peak-Ring Basins on the Moon: Implications for Basin Formation

    Science.gov (United States)

    Baker, D. M.; Head, J. W.; Neumann, G. A.; Smith, D. E.; Zuber, M. T.

    2012-12-01

    Reassessment of the formation of peak-ring basins on the Moon using image and altimetry data from the Lunar Reconnaissance Orbiter has yielded a number of morphometric properties of these basin types that are helping to constrain the processes leading to their formation and the formation of larger multi-ring basins [1,2]. These analyses demonstrate the importance of the volume and depth of impact melting in modifying the interior morphology of large impact craters. At the onset diameter of peak-ring basins, the depth of the basin's melted zone approaches the depth of the transient crater, creating a strengthless interior melt cavity that facilitates gravitational collapse of the transient crater. The melt cavity suppresses central peak formation, and peak rings are formed outward from the melt zone boundary by the interaction of deep-seated rotational faults in the collapsing wall of the transient crater and huge vertical uplifts in the central portions of the basin. The final configuration of the peak-ring basin has a kilometers-thick slab of cooled residual impact melt resting on an uplifted mantle plug with little or no unmelted crustal material. Highly faulted and fractured, dilatant and possibly thickened crust should occur below and outward from the peak ring due to inward and upward translation of collapsed transient crater rim material. As a result of this configuration, the gravity structure should reflect an anomalously high density, uplifted impact melt plus mantle zone spatially confined to within the peak ring. Surrounding this should be a highly fractured, low density zone of possibly thickened crust. Bouguer gravity anomalies derived from Gravity Recovery and Interior Laboratoy (GRAIL) gravity data and Lunar Orbiter Laser Altimeter (LOLA) altimetry data show spatial patterns that are consistent with those predicted by the formation model briefly outlined above. Nearly all 17 peak-ring basins that have been cataloged on the Moon show positive Bouguer gravity anomalies that are spatially confined within the peak ring. The magnitudes of the anomalies are variable, but appear to be less prominent in the smallest peak-ring basins. These observations are consistent with enhanced crustal densities resulting from thinned crust and extreme uplift of the interior melt zone and mantle below. In many of the basins, the annulus between the peak ring and rim crest shows a Bouguer gravity anomaly that is reduced relative to crust exterior to the rim crest. This is consistent with low density, highly faulted and fractured, dilatant crust resulting from the collapse of the transient cavity and formation of the peak ring. The peak rings show gravity anomalies intermediate between the positive central anomaly and reduced gravity annulus, suggesting that peak rings form at the boundary of the uplifted melt plus mantle plug and the zone of highly fractured or thickened crust. Further quantification of the gravity anomalies and comparisons with the predicted density and crustal structure below peak-ring basins will help to better constrain the preliminary observations presented here. References: [1] Baker et al. (2011) Icarus, 214, 377-393. [2] Baker, D.M.H. et al. (2012) J. Geophys. Res., 117, E00H16.

  11. 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...

  12. A New Search for Lunar Mascon Basins using Detrended Kaguya (SELENE) Gravity: Implications for GRAIL

    Science.gov (United States)

    Dombard, A. J.; Hauck, S. A.; Balcerski, J.

    2012-12-01

    The collection of GRAIL data and imminent release of its first gravity models will revolutionize understanding of the lunar interior, which motivates an assessment of the current state of knowledge. A primary goal of the GRAIL mission is to understand better mascon basins, large impact craters that display significant positive free-air and Bouguer gravity anomalies. Discovered in a handful of nearside basins during preparations for the Apollo landings and recently expanded by the global Kaguya (SELENE) gravity models, an important question is why is not every large crater a mascon basin, as less than half of the 41 impact basins > 300 km in diameter (minus South Pole-Aitken) have been previously determined to be mascons. An issue not generally considered in the identification of mascons is that the topography, and hence Bouguer gravity, display long-wavelength regional signals that might mask some mascons. Here, we use the SGM100i Kaguya gravity model and LRO's LOLA shape model to examine the free-air, topographic (arising solely from topography), and Bouguer gravity, detrended by omitting the first 5 spherical harmonic degrees from our expansions. In contrast to past studies, we find that most large basins (28 of 41) display characteristics of mascons (e.g., a strong positive Bouguer anomaly generally narrower than the surface rim). Negative annuli surrounding the central highs in the free-air gravity do not exist in the Bouguer gravity, with only 2 definitive exceptions. The fact that the majority of the Bouguer anomalies are narrower than the basin rim and that the negative free-air annulus appears to be a product of the surface topography has implications for the formation of the basins. We propose that beneath a forming large basin, the mantle uplifts in response to the large isostatic imbalance with the transient crater, while the surface topography forms from not only upward but inward collapse of the transient crater's rim wall and adjustment of the melt sheet. The combination of a mass excess from the uplifted mantle and a wider mass deficit from the surface basin yields the bulls-eye gravity signature of these basins. Furthermore, the 13 non-mascon basins are all ancient (pre-Nectarian) with a heavily degraded surface morphology. That the impact basins lacking positive Bouguer anomalies correspond with ancient, heavily degraded basins suggests that a post-impact evolutionary process has taken place. This notion dovetails with past work on large craters on both the Moon and Mars that demonstrates the crust beneath these basins is capable of flowing and relaxing the crust-mantle topography. Our results suggest that the formation of mascons is the standard, not the exception, for large impacts on the Moon. Moreover, the occurrence of lower crustal flow in basins only in the pre-Nectarian has important consequences for the cooling history of the Moon. [This work was supported by NASA Grant NNX08AZ03G.

  13. Williston Reservoir: Site preparation and post-flood cleanup

    International Nuclear Information System (INIS)

    Williston Reservoir is the second largest in Canada and ranks ninth on the world scale. It was formed by the construction of the W.A.C. Bennet Dam and is the most important hydroelectric storage reservoir and largest body of fresh water in British Columbia. Site preparation for the reservoir began in 1962, with pre-flood clearing involving salvage of merchantable timber, handfalling, machine downing, burning of slash and burial. Post-flood cleanup included timber salvage, bailing and burning debris, tractor piling and burning, crane piling in shallows, underwater cutting, and hand cutting during low drawdown. Various types of floating debris have presented problems for recreational use, log booming and transport, waterways and aviation. Protection of the spillway is accomplished with a floating boom upstream of the channel. Administration, funding, forest clearance, salvage methods, clearing standards, wood volumes, project costs, environmental concerns, and future priorities are discussed. 5 figs., 2 tabs

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

    Directory of Open Access Journals (Sweden)

    Richard Mason

    2012-03-01

    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 setting 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.

  15. 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.

  16. Rain Basin Design Implications for Soil Microbial Activity and N-mineralization in a Semi-arid Environment

    Science.gov (United States)

    Stern, C.; Pavao-Zuckerman, M.

    2014-12-01

    Rain basins have been an increasingly popular Green Infrastructure (GI) solution to the redistribution of water flow caused by urbanization. This study was conducted to examine how different approaches to basin design, specifically mulching (gravel vs. compost and gravel), influence the water availability of rain basins and the effects this has on the soil microbial activity of the basins. Soil microbes are a driving force of biogeochemical process and may impact the carbon and nitrogen dynamics of rain basin GI. In this study we sampled 12 different residential-scale rain basins, differing in design established at Biosphere 2, Arizona in 2013. Soil samples and measurements were collected before and after the onset of the monsoon season in 2014 to determine how the design of basins mediates the transition from dry to wet conditions. Soil abiotic factors were measured, such as moisture content, soil organic matter (SOM) content, texture and pH, and were related to the microbial biomass size within the basins. Field and lab potential N-mineralization and soil respiration were measured to determine how basin design influences microbial activity and N dynamics. We found that pre-monsoon basins with compost had higher moisture contents and that there was a positive correlation between the moisture content and the soil microbial biomass size of the basins. Pre-monsoon data also suggests that N-mineralization rates for basins with compost were higher than those with only gravel. These design influences on basin-scale biogeochemical dynamics and nitrogen retention may have important implications for urban biogeochemistry at neighborhood and watershed scales.

  17. 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.; A. Sarkar; 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...

  18. Irrigation efficiency and water-policy implications for river-basin resilience

    Directory of Open Access Journals (Sweden)

    C. A. Scott

    2013-07-01

    Full Text Available Rising demand for food, fiber, and biofuels drives expanding irrigation withdrawals from surface- and groundwater. Irrigation efficiency and water savings have become watchwords in response to climate-induced hydrological variability, increasing freshwater demand for other uses including ecosystem water needs, and low economic productivity of irrigation compared to most other uses. We identify three classes of unintended consequences, presented here as paradoxes. Ever-tighter cycling of water has been shown to increase resource use, an example of the efficiency paradox. In the absence of effective policy to constrain irrigated-area expansion using "saved water", efficiency can aggravate scarcity, deteriorate resource quality, and impair river-basin resilience through loss of flexibility and redundancy. Water scarcity and salinity effects in the lower reaches of basins (symptomatic of the scale paradox may partly be offset over the short-term through groundwater pumping or increasing surface water storage capacity. However, declining ecological flows and increasing salinity have important implications for riparian and estuarine ecosystems and for non-irrigation human uses of water including urban supply and energy generation, examples of the sectoral paradox. This paper briefly examines policy frameworks in three regional contexts with broadly similar climatic and water-resource conditions – central Chile, southwestern US, and south-central Spain – where irrigation efficiency directly influences basin resilience. The comparison leads to more generic insights on water policy in relation to irrigation efficiency and emerging or overdue needs for environmental protection.

  19. Finding the boundary between evolutionary basins of attraction, and implications for Wright's fitness landscape analogy

    Science.gov (United States)

    Weinreich, Daniel M.; Sindi, Suzanne; Watson, Richard A.

    2013-01-01

    In 1932 Wright introduced the notion of the fitness landscape. By analogy with a physical landscape, whose gradient predicts a rolling marble's spatial trajectory, the contours of the fitness landscape are meant to predict an evolving population's genetic trajectory. Wright's chief interest was in the possibility that mutational interactions might frustrate natural selection, giving rise to multiple maxima on the fitness landscape. Here we study a dynamical system over the state space defined by allele frequencies and linkage disequilibria between alleles. We first analytically locate the saddle between basins of attraction in infinite-sized populations evolving under the influence of selection and recombination for the simplest two-locus case. We further show numerically that the boundary between basins is approximately linear with respect to linkage disequilibrium, though not allele frequency. We also employ this framework to develop novel perspectives on two venerable results for single-peaked fitness landscapes. Finally we sought the potential function whose contours would predict evolutionary trajectories through this state space. Importantly not every dynamical system can be described by a potential function, and the present problem is provably one such case. Thus in the parlance of Wright's analogy, in locating the floor of the fitness valley we have lost the landscape, and this conclusion is not limited to our choice of parameterization, nor of problem. This result motivates us to carefully review the formal implications and requirements of this widely used analogy.

  20. Finding the boundary between evolutionary basins of attraction, and implications for Wright's fitness landscape analogy

    International Nuclear Information System (INIS)

    In 1932 Wright introduced the notion of the fitness landscape. By analogy with a physical landscape, whose gradient predicts a rolling marble's spatial trajectory, the contours of the fitness landscape are meant to predict an evolving population's genetic trajectory. Wright's chief interest was in the possibility that mutational interactions might frustrate natural selection, giving rise to multiple maxima on the fitness landscape. Here we study a dynamical system over the state space defined by allele frequencies and linkage disequilibria between alleles. We first analytically locate the saddle between basins of attraction in infinite-sized populations evolving under the influence of selection and recombination for the simplest two-locus case. We further show numerically that the boundary between basins is approximately linear with respect to linkage disequilibrium, though not allele frequency. We also employ this framework to develop novel perspectives on two venerable results for single-peaked fitness landscapes. Finally we sought the potential function whose contours would predict evolutionary trajectories through this state space. Importantly not every dynamical system can be described by a potential function, and the present problem is provably one such case. Thus in the parlance of Wright's analogy, in locating the floor of the fitness valley we have lost the landscape, and this conclusion is not limited to our choice of parameterization, nor of problem. This result motivates us to carefully review the formal implications and requirements of this widely used analogy

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

    OpenAIRE

    Khaghaninia, Samad; Shakeryari, Abbas; Hayat, Ru?stem

    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.

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

    OpenAIRE

    Collot, Julien; Herzer, R.; Lafoy, Y.; 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...

  3. 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.

  4. Watershed Characteristics and Their Implication for Hydrologic Response in the Upper Sokoto Basin, Nigeria

    OpenAIRE

    Ifabiyi Ifatokun Paul; Eniolorunda Nathaniel Bayode

    2012-01-01

    Most African river basins lack flow data, a condition which has affected river basin operations. Flood is a common occurrence on the Sokoto basin but poor data base has affected various research efforts and flood mitigation attempts in the basin. This present study will study basin variables using a GIS approach with a few to gaining insights to the flood potentials of Sokoto basin. Shuttle Radar Topographic Mission (SRTM) image covering 5o-7o E and 12 o to 14oN was used in this study. The an...

  5. 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 tabshabitat lands. 13 figs., 4 tabs

  6. 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].

  7. Watershed Characteristics and Their Implication for Hydrologic Response in the Upper Sokoto Basin, Nigeria

    Directory of Open Access Journals (Sweden)

    Ifabiyi Ifatokun Paul

    2012-05-01

    Full Text Available Most African river basins lack flow data, a condition which has affected river basin operations. Flood is a common occurrence on the Sokoto basin but poor data base has affected various research efforts and flood mitigation attempts in the basin. This present study will study basin variables using a GIS approach with a few to gaining insights to the flood potentials of Sokoto basin. Shuttle Radar Topographic Mission (SRTM image covering 5o-7o E and 12 o to 14oN was used in this study. The analysis was carried out using the Integrated Land and Water Information System (ILWIS and ArcGIS environments. Sinks were removed from the STRM, and the flow direction map was generated as an input for drainage extraction, river ordering and basin catchment extraction. Drainage network overlay was carried out on the generated hill-shade map and on a portion of SPOT image covering the Upper Sokoto catchment for visual analysis. Altogether, 44 basin variables were generated with a view to appraising flood and water resource management in the basin. The results showed that the Upper Sokoto basin is an alluvial catchment; located in a relatively low lying area where high level of deposition is experienced. It is sinuous in nature, circular in shape and compact. These characteristics coupled with the relatively high volume of precipitated water of 14,511,439,620 m³/year are indications that the basin has high flood potential. The paper recommends construction of levees to protect farmlands, efficient reservoir operation and sustainable watershed management for the purpose of environmental management in the Sokoto basin.

  8. Nodal basin recurrence following lymph node dissection for melanoma: implications for adjuvant radiotherapy

    International Nuclear Information System (INIS)

    Purpose: To analyze patterns of failure in malignant melanoma patients with lymph node involvement who underwent complete lymph node dissection (LND) of the nodal basin. To determine prognostic factors predictive of local recurrence in the lymph node basin in order to select patients who may benefit from adjuvant radiotherapy. Methods and Materials: A retrospective analysis of 338 patients undergoing complete LND for melanoma between 1970 and 1996 who had pathologically involved lymph nodes was performed. Mean follow-up from the time of LND was 54 months (range: 12-306 months). Lymph node basins dissected included the neck (56 patients), axilla (160 patients), and groin (122 patients). Two hundred fifty-three patients (75%) underwent therapeutic LND for clinically involved nodes, while 85 patients (25%) had elective dissections. Forty-four percent of patients received adjuvant systemic therapy. No patients received adjuvant radiotherapy to the lymph node basin. Results: Overall and disease-specific survival for all patients at 10 years was 30% and 36%, respectively. Overall nodal basin recurrence was 30% at 10 years. Mean time to nodal basin recurrence was 12 months (range: 2-78 months). Site of nodal involvement was prognostic with 43%, 28%, and 23% nodal basin recurrence at 10 years with cervical, axillary, and inguinal involvement, respectively (p = 0.008). Extracapsular extension (ECE) led to a 10-year nodal basin failure rate of 63% vs. 23% without ECE (p 10 nodes involved (p 0.0001). There was no significant difference in nodal basin control in patients with synchronous or metachronous lymph node metastases, nor in patients receiving or not receiving adjuvant systemic therapy. Nodal basin failure was predictive of distant metastasis with 87% of patients with nodal basin recurrence developing distant disease compared to 54% of patients without nodal failure (p 3 positive lymph nodes, clinically involved nodes, or any node larger than 3 cm. Patients with these risk factors should be considered for adjuvant radiotherapy to the lymph node basin to reduce the incidence of nodal basin recurrence. Patients with nodal basin failure are at higher risk of developing distant metastases

  9. Silviculture of eucaliptus plantations in the Paraiba do Sul basin, Brazil, and its potential implication on the basin ecohydrology.

    Science.gov (United States)

    Carriello, Felix; Andres Rodriguez, Daniel; Marques Neves, Otto; Vicens, Raul

    2014-05-01

    Silviculture of eucaliptus plantations is an important driver of the Mata Atlântica biome conversion into another land use in the Paraíba do Sul basin, in the southeastern of Brazil. This region is located in one of the most developed areas in Brazil, between Rio de Janeiro and São Paulo, the most important cities in Brazil, linked by Presidente Dutra highway. Between both cities there are another cities that produce a variety of goods - from meat to planes, cars and mobile phones. This area is, at the same time, one the most important hot spot for the Mata Atlântica biome. Here we have a large Mata Atlântica fragment protected by law and others fragments being conversed to pasture, agriculture, silviculture and urban areas. Paraiba do Sul river drains the region and runs into Rio de Janeiro State. The basin is highly anthropized, with multiple approaches of its waters resources. Its waters also serve Rio de Janeiro metropolitan area. Because land use and land cover changes impact the water yield in a basin, the study of its dynamic its of great importance for water resources management. We study the land use and land cover change in the region between 1986 and 2010, focusing in the development of silviculture of eucaliptus plantations. We used the HAND (Height Above Nearest Drainage) approach that uses the height above the nearest water body, acquired from SRTM Data and transformed into a Terrain Numeric Mode, to classify the landscape into three different ecohydrological environments: floodplain, mountain top and hillslope. This classes were intersected with 1986 and 2010 land use and cover change classification obtained from Landsat imagery. Results show that silviculture has increased in the region from 1986 to 2010. In both years, silviculture areas are mainly located at the hillslope (47%), while floodplain and mountain top share 28 % and 23 % respectively. Available census data from the Brazilian Institute of Geography and Statistics, IBGE, for 1995 and 2006 years, show an increment in the number of small farmers, from 27 to 196, that are planting eucalyptus sp in the region and also an increase in the whole silvicuture production. Silviculture of eucaliptus plantations is recognized to be a great water consuming and a driver of water pollution by pesticides and fertilizers. The study carried out combines a landscape descriptor with land use and land cover changes mapping to provide an important database for ecohydrological studies, regarding the water resources management.

  10. Tectono-thermal History of the Southern Nenana Basin, Interior Alaska: Implications for Conventional and Unconventional Hydrocarbon Exploration

    Science.gov (United States)

    Dixit, N. C.; Hanks, C. L.

    2014-12-01

    The Tertiary Nenana basin of Interior Alaska is currently the focus of both new oil exploration and coalbed methane exploitation and is being evaluated as a potential CO2sequestration site. The basin first formed as a Late Paleocene extensional rift with the deposition of oil and gas-prone, coal-bearing non-marine sediments with excellent source potential. Basin inversion during the Early Eocene-Early Oligocene times resulted in folding and erosion of higher stratigraphic levels, forming excellent structural and stratigraphic traps. Initiation of active faulting on its eastern margin in the middle Oligocene caused slow tectonic subsidence that resulted in the deposition of reservoir and seal rocks of the Usibelli Group. Onset of rapid tectonic subsidence in Pliocene that continues to the present-day has provided significant pressure and temperature gradient for the source rocks. Apatite fission-track and vitrinite reflectance data reveals two major paleo-thermal episodes: Late Paleocene to Early Eocene (60 Ma to 54.8 Ma) and Late Miocene to present-day (7 Ma to present). These episodes of maximum paleotemperatures have implications for the evolution of source rock maturity within the basin. In this study, we are also investigating the potential for coalbed methane production from the Late Paleocene coals via injection of CO2. Our preliminary analyses demonstrate that 150 MMSCF of methane could be produced while 33000 tonnes of CO2 per injection well (base case of ~9 years) can be sequestered in the vicinity of existing infrastructure. However, these volumes of sequestered CO2and coal bed methane recovery are estimates and are sensitive to the reservoir's geomechanical and flow properties. Keywords: extensional rift, seismic, subsidence, thermal history, fission track, vitrinite reflectance, coal bed methane, Nenana basin, CO2 sequestration

  11. 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.; F. Guillocheau

    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...

  12. 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.

  13. 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.

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

    Directory of Open Access Journals (Sweden)

    Eze Bassey Eze

    2010-08-01

    Full Text Available 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 respectively. The basin was found to be stronglyelongated with circularity ratio of 0.34 and elongation ratio of 0.64. The average bifurcation ratio was 2.83. Thevery low value of drainage intensity implies that drainage density and stream frequency have very little effect onthe extent to which the surface has been lowered by agents of denudation. These low values of drainage density,stream frequency and drainage intensity also imply that surface runoff is not quickly removed from the basin,making it susceptible to flooding, gully erosion and landslides, particularly in the lower part of the basin. It istherefore recommended that human activities that could impact negatively on stream network in the basin shouldbe discouraged.

  15. Calibration approaches for distributed hydrologic models in poorly gaged basins: implication for streamflow projections under climate change

    Science.gov (United States)

    Wi, S.; Yang, Y. C. E.; Steinschneider, S.; Khalil, A.; Brown, C. M.

    2015-02-01

    This study tests the performance and uncertainty of calibration strategies for a spatially distributed hydrologic model in order to improve model simulation accuracy and understand prediction uncertainty at interior ungaged sites of a sparsely gaged watershed. The study is conducted using a distributed version of the HYMOD hydrologic model (HYMOD_DS) applied to the Kabul River basin. Several calibration experiments are conducted to understand the benefits and costs associated with different calibration choices, including (1) whether multisite gaged data should be used simultaneously or in a stepwise manner during model fitting, (2) the effects of increasing parameter complexity, and (3) the potential to estimate interior watershed flows using only gaged data at the basin outlet. The implications of the different calibration strategies are considered in the context of hydrologic projections under climate change. To address the research questions, high-performance computing is utilized to manage the computational burden that results from high-dimensional optimization problems. Several interesting results emerge from the study. The simultaneous use of multisite data is shown to improve the calibration over a stepwise approach, and both multisite approaches far exceed a calibration based on only the basin outlet. The basin outlet calibration can lead to projections of mid-21st century streamflow that deviate substantially from projections under multisite calibration strategies, supporting the use of caution when using distributed models in data-scarce regions for climate change impact assessments. Surprisingly, increased parameter complexity does not substantially increase the uncertainty in streamflow projections, even though parameter equifinality does emerge. The results suggest that increased (excessive) parameter complexity does not always lead to increased predictive uncertainty if structural uncertainties are present. The largest uncertainty in future streamflow results from variations in projected climate between climate models, which substantially outweighs the calibration uncertainty.

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

    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...

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

    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...

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

    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...

  19. Stress magnitude and orientation in the Potiguar Basin, Brazil: Implications on faulting style and reactivation

    Science.gov (United States)

    Reis, Álvaro F. C.; Bezerra, Francisco H. R.; Ferreira, Joaquim M.; Nascimento, Aderson F.; Lima, Cláudio C.

    2013-10-01

    analyzed borehole breakout data and drilling-induced tensile fractures derived from resistivity image logs run at 10 oil wells to derive the orientation of the maximum horizontal stress SHmax from the Potiguar Basin in the continental margin of Brazil. Stress magnitudes are derived from density logs for the vertical stress, mini-frac tests for the minimum horizontal stress Shmin, and rock strength laboratory analysis to estimate the SHmax magnitudes. We compared these results with the stress regime and SHmax orientation derived from nine earthquake series located in the crystalline basement, where seismicity is concentrated, and previous breakout data from the basin. In the basin, the SHmax gradient is 20.0 MPa/km, and the SHmax/Shmin ratio is 1.154, indicating a normal tectonic stress regime from 0.5 to 2.0 km, whereas the SHmax gradient of 24.5 MPa/km and SHmax/Shmin ratio of 1.396 indicate a transition from a normal to strike-slip stress regime at 2.5 to 4.0 km. The deeper stress regime in the basin is similar to that in the basement at 1-12 km depth. This transition of the tectonic stress regime is consistent with an incipient tectonic inversion in the basin. We note that the SHmax orientation rotates from NW-SE in the western part of the Potiguar Basin to E-W in its central and eastern parts, roughly following the shoreline geometry, indicating that local features such as flexural stresses influence the local (scale < 100 km) stress pattern. We also conclude that the basement is critically stressed, but not the basin.

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

    International Nuclear Information System (INIS)

    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. (Author) 16 refs.

  1. 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

  2. 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.

  3. 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...

  4. Implications of the Projected Future Climate on Water Resources in the Indian Sub-continent Basins

    Science.gov (United States)

    Shah, H. L.; Mishra, V.

    2014-12-01

    Sustainability of water resources is vital for agricultural and socio-economic development in India. In the recent few decades, India has been witnessing erratic nature of the Indian summer monsoon, which accounts for about 80% of the total annual rainfall. While there is a large uncertainty in the precipitation projections during the summer monsoon from the regional and global climate models, we need to understand sensitivity of water resources in the Indian sub-continental river basins under the projected future climate. This is particularly important as the Indian sub-continent is one of the most populated regions of the world. We evaluated changes in water budget in the 18 Indian sub-continental basins under the projected future climate using the Variable Infiltration Capacity (VIC) model. The VIC model was calibrated and evaluated using the observed streamflow as well as satellite derived evapotranspiration and soil moisture. After the successful calibration and evaluation, we performed a sensitivity analysis for the water balance variables. Finally, we used downscaled and bias corrected climate forcings to develop scenarios of changes in water balance under the future climate. Despite the intermodal variation, Indian basins are projected to experience wetter and warmer climate in future. Results indicate positive changes in evapotranspiration and runoff under the projected future climate; however, increases in total runoff are projected to be significant in most of the basins in the sub-continent.

  5. 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

  6. 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

    OpenAIRE

    Ennio Marsella; Vincenzo Di Fiore; Anna Giuseppa Cicchella; Gemma Aiello

    2011-01-01

    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 margi...

  7. Assessing regional hydrology and water quality implications of large-scale biofuel feedstock production in the Upper Mississippi River Basin.

    Science.gov (United States)

    Demissie, Yonas; Yan, Eugene; Wu, May

    2012-08-21

    A recent U.S. Department of Energy study estimated that more than one billion tons of biofuel feedstock could be produced by 2030 in the United States from increased corn yield, and changes in agricultural and forest residue management and land uses. To understand the implications of such increased production on water resources and stream quality at regional and local scales, we have applied a watershed model for the Upper Mississippi River Basin, where most of the current and future crop/residue-based biofuel production is expected. The model simulates changes in water quality (soil erosion, nitrogen and phosphorus loadings in streams) and resources (soil-water content, evapotranspiration, and runoff) under projected biofuel production versus the 2006 baseline year and a business-as-usual scenario. The basin average results suggest that the projected feedstock production could change the rate of evapotranspiration in the UMRB by approximately +2%, soil-water content by about -2%, and discharge to streams by -5% from the baseline scenario. However, unlike the impacts on regional water availability, the projected feedstock production has a mixed effect on water quality, resulting in 12% and 45% increases in annual suspended sediment and total phosphorus loadings, respectively, but a 3% decrease in total nitrogen loading. These differences in water quantity and quality are statistically significant (p < 0.05). The basin responses are further analyzed at monthly time steps and finer spatial scales to evaluate underlying physical processes, which would be essential for future optimization of environmentally sustainable biofuel productions. PMID:22827327

  8. Seismic Characteristics and Evolution of Intrusion in Qiongdongnan Basin: Implications for the Rifting of South China Sea

    Science.gov (United States)

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

    2014-12-01

    The South China Sea (SCS) formed by magma-poor rifting in the Paleogene. The Qiongdongnan basin (QDNB) located at the north margin was thought to completely lack magma activities. Due to the limited amount of deepwater drills, magmas in deepwater area had been ignored in petroleum exploration, and thus our knowledge of basin analysis is far from complete. Based on a comprehensive study on seismic profiles and P wave velocity data, 12 intrusion-related seismic reflection anomalies in QDNB have been recognized. In the southwest of QDNB, gas chimneys and gas clouds have been found with a low velocity (6 km/s), a positive magnetic anomaly and a high gravity anomaly. In addition, according to different dips of marginal facies, three phases of diapirism can be identified (32 Ma, 15.5 Ma and 10.5 Ma). Along a narrow area with hyper-extended crust, those intrusions document the opening of SCS at 32 Ma and the volcanic activities afterwards. The results are corresponding to the fact that all of the intrusions in QDNB occurred during the extreme crustal thinning process and after the cessation of seafloor spreading, and thus the intrusion evolved with time would have major implications for post-rift emplacement.

  9. Subsurface images of the northern Newark basin, New York, USA and their implications for carbon sequestration

    Science.gov (United States)

    Olsen, P. E.; Withjack, M. O.; Schlische, R. W.; Goldberg, D.; Kent, D. V.; Tamulonis, K.; Couëslan, M.; Collins, D. J.

    2011-12-01

    The Triassic-Jurassic Newark rift, a large onshore sedimentary basin close to northeast US metropolitan areas, may have potential for safe geological storage of CO2 in a suitably deep formation overlain by appropriate confining units. Filled with continental synrift sedimentary rocks and CAMP (Central Atlantic Magmatic Province) basaltic intrusions and flows, the basin is bounded on the NW by the NE-striking, SE-dipping Ramapo fault. Funded by the Department of Energy's (DOE) National Energy Technology Laboratory's (NETL) Carbon Sequestration Program's portion of the American Recovery and Reinvestment Act of 2009 (ARRA) and NYSERDA, the TriCarb Consortium for Carbon Sequestration acquired two seismic-reflection profiles in Rockland County, NY that were processed to obtain depth-migrated images of the basin's subsurface geometry. The E-trending dip profile crosses most of the basin, while the shorter N-trending profile provides a strike-view. Five seismic facies are present: (1) shallow continuous, closely spaced, W-dipping reflections suggestive of lacustrine deposits; (2) short, non-coherent reflections suggestive of conglomeritic fluvial strata; (3) high-amplitude parallel reflections, locally exhibiting reverse separation, suggestive of prerift early Paleozoic strata Cambro-Ordovician carbonates; (4) a facies at the bottom of both lines and the western end of the ESE-trending line that lacks reflections, suggestive of prerift metamorphic rocks such as Precambrian gneiss, and/or highly deformed Taconic (Ordovician) phyllites; and (5) a seismically transparent band commonly bounded by high-amplitude reflections that cuts across the stratigraphy of facies 1-3, suggestive of a scoop-shaped intrusive diabase sheet that projects to the surface to outcrops of the CAMP-related Palisade sill. Basin geometry is well-imaged conforming to a deeply eroded half graben. Reflections of facies 3 are truncated by facies 2 marking the angular pre-rift unconformity. Distinct fanning in facies 1 suggests syndepositional faulting with reflections dipping and thickening toward the poorly imaged Ramapo fault to the NW. Because Jurassic CAMP lavas crop out at the NW edge of the basin, the full thickness of Triassic strata are imaged on the seismic data. Our favored interpretation has the Palisade sheet intruding the pre-rift unconformity in the axis of the basin, climbing up-section into Triassic strata to the NW, NE, and SE. The base of the intrusion and the contact with prerift strata appears to be at a depth of ~ 2 km (6600 ft) in the location of a planned basin-characterization core hole to be drilled in late summer/early fall of 2011. In this location, our favored interpretation has the intrusion underlying Triassic sandstones and conglomerates of the Stockton Formation (best reservoir candidate), in turn overlain by mudstones of the Lockatong Formation (best confining unit candidate), overlain by upwardly coarsening mudstones, sandstones, and conglomerates of the Passaic Formation. These hypotheses should be tested by "ground truth" from the borehole by the time of this presentation.

  10. Basin-scale hydrodynamics in a Mediterranean reservoir. Implications for the phytoplankton dynamics

    OpenAIRE

    Vidal Hurtado, Javier

    2007-01-01

    Physical processes determine, to a large degree, the ecological response of a reservoir to inflows, outflows and meteorological forcing. This PhD thesis therefore aims to give an assessment of the main physical mechanisms governing Mediterranean reservoirs. The main basin-scale hydrodynamical processes are the generation of seiches and the gravity currents generated by the river inflow. The periodicity of the wind forcing makes that the reservoir responses as a forced harmonic damped oscillat...

  11. Seismic Stratigraphy of the Central South China Sea Basin and Implications for Neotectonics

    Science.gov (United States)

    Li, C. F.; Ding, W.; Franke, D.; Yao, Y.; Pang, X.; Shi, H.; Li, J.; Cao, Y.

    2014-12-01

    International Ocean Discovery Program (IODP) Expedition 349 drilled five sites in the central South China Sea Basin. Three sites (U1431 in the East Subbasin, and U1433 and U1434 in the Southwest Subbasin) reached basalt interpreted to be igneous basement of the oceanic crust. Site U1435 on the northern continent-ocean boundary recovered pre-Oligocene sedimentary rocks deposited prior to the opening of the South China Sea. Furthermore, a full suite of geophysical logging was also carried out at Sites U1431 and U1433. These coring and logging data and physical property measurements are integrated with, and correlated to, regional reflection seismic data to map regional sequence stratigraphic boundaries and seismic facies of the central basin and the continent-ocean transition zone. With our carefully selected seismic profiles, stratigraphic correlation is possible even between the continent-ocean transition zone and the central basin, circumventing preexisting basement highs near the continent-ocean boundary that often prevent direct correlation. We interpret four sequence boundaries, which are Oligocene/Miocene, middle Miocene/late Miocene, Miocene/Pliocene, and Pliocene/Pleistocene boundaries. Seismic facies between sequence boundaries are often characteristic and distinctive, allowing relatively straightforward regional correlation. For example, massive Miocene carbonate deposits, if well consolidated, are readily distinguishable by strong seismic reflectivities, caused by their relatively higher density and velocity in contrast to those of interbedded turbidite clastic sediments. However, we found abrupt seismic facies changes both temporally and spatially. In particular, the fossil spreading ridge and the Zhongnan ridge between the East and Southwest Subbasins acted as major sedimentary barriers, across which seismic facies changes sharply and cannot be easily correlated. The well-constrained seismic sequence boundaries also allow us to estimate the timing of post-spreading volcanism, faulting and vertical movement in the central basin.

  12. Geochemical indicators of hydrogeologically isolated structures in the Danube Basin; implications for potential gas storage objects

    OpenAIRE

    Tomáš Lánczos; Ján Mili?ka; Miroslav Pereszlényi

    2011-01-01

    One of the key conditions for underground gas storage (UGS) objects establishment is the presence of hydrogeologically isolated structures. These are mainly exhausted hydrocarbon deposits and aquifers in the Cenozoic fill and the basement of the Danube Basin. The geochemical indicators used to determine the aquifer isolation level of potential underground gas storage objects are based on the ratio of stagnant and dynamic water components. The most widely used indicator is the rHCO3/rCl molar ...

  13. Implications of Transient Deformation in the Northern Basin and Range, Western United States

    Science.gov (United States)

    Chamoli, A.; Lowry, A. R.; Jeppson, T.

    2013-12-01

    Coherent transient events observed in Global Positioning System (GPS) data from the Basin and Range extensional province may help to illuminate qualitatively similar transient events observed in subduction zones and other tectonic environments. We examine GPS time series at twenty-two sites using a time series modeling approach that combines hyperbolic tangent function analysis (HTFA) with elastic load deformation estimated independently from climatological data sets. We identify two transient events, ~2000.4 and ~2004.4, with roughly similar timing and similar displacement to transients described previously by other research groups. The first few years of GPS observations, adopted as a reference state in earlier studies, are also found to be anomalous. Our results differ from previous studies in two respects. First, we find that a significant component of northward transient motion occurs during both the ~2000.4 and ~2004.4 events, despite a reversal of sign in east component motion. Second, both of these events affect sites coherently in the eastern as well as the western Basin and Range. Examination of independently-derived surface mass loading, the largest source of transient stress forcing in the region, reveals no evidence of a simple relationship. These observations suggest Basin and Range transients are similar to slow-slip events in subduction zones in that they require a mechanism involving state-dependent behavior, and they are sensitive to exceedingly small perturbations in ambient stress. Previous studies inferred slip on a single, province-wide megadetachment at the Moho, but that hypothesis assumes negligible ductile deformation of the lower crust and a dry olivine rheology for the uppermost mantle. Recent measurements of crustal quartz abundance and effective elastic thickness suggest both assumptions are unlikely. Basin and Range transients can be reconciled with the frictional slip mechanism most widely accepted for subduction zone transient events provided that slip is occurring on discontiguous detachment surfaces at mid-crustal depths.

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

    Directory of Open Access Journals (Sweden)

    D.R. Archer

    2004-01-01

    Full Text Available 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 precipitation at stations over the entire region, so that, for practical forecasting of summer runoff in some basins, a single valley-floor precipitation station can be used In contrast, spatial relationships in seasonal precipitation are weaker in summer and sometimes significantly negative between stations north and south of the Himalayan divide. Although analysis of long datasets of precipitation from 1895 shows no significant trend, from 1961–1999 there are statistically significant increases in winter, in summer and in the annual precipitation at several stations. Preliminary analysis has identified a significant positive correlation between the winter North Atlantic Oscillation (NAO and winter precipitation in the Karakoram and a negative correlation between NAO and summer rainfall at some stations. Keywords: upper Indus basin, climate change, time series analysis, spatial correlation, teleconnections

  15. Thermal maturity history and implications for hydrocarbon exploration in the Catatumbo basin, Colombia

    International Nuclear Information System (INIS)

    A thermal model integrated with oil and gas geochemical study has been constructed for the Catatumbo basin, Colombia for provides 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 of 1 0 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 youngest 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 for 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 oilhern area appears more prospective for oil with minor amounts of gas

  16. Diversity of Manota Williston (Diptera, Mycetophilidae) in Ulu Temburong National Park, Brunei

    Science.gov (United States)

    Šev?ík, Jan; Hippa, Heikki; Wahab, Rodzay Abdul

    2014-01-01

    Abstract A total of 15 species of Manota Williston, 1896 are recorded from Brunei, based on the investigations in 2013-2014. Thirteen species are recorded from Ulu Temburong National Park and three species from the Universiti Brunei Darussalam Campus in Tungku. Six species are described as new to science: Manota belalongensis sp. n., M. kaspraki sp. n., M. macrothrix sp. n., M. megachaeta sp. n. and M. pileata sp. n. from Ulu Temburong, and M. ricina sp. n. from Tungku. New records of the following species are given: Manota bifida Hippa & Papp, M. bruneiensis Hippa & Šev?ík, M. hyboloma Hippa & Šev?ík, M. oligochaeta Hippa, M. pappi Hippa, M. perangulata Hippa & Šev?ík, M. pollex Hippa, M. procera Hippa and M. simplex Hippa. PMID:25901110

  17. Different aerosol loading and their radiative implication over Indo-Gangetic Basin

    Science.gov (United States)

    Tiwari, Shani; Singh, Abhay Kumar; Srivastava, Atul Kumar

    Abstract: The climate and environmental effects of atmospheric aerosols are presently the most critical issues in global science community because of their various emission sources and different impacts to earth’s radiation budget. Different types of atmospheric aerosols have different optical as well as radiative properties which are crucial to reduce possible uncertainties in climate forcing. Indo-Gangetic Basin (IGB)in northern part of India has been recognized for different types of aerosol loading due to various emission sources (natural and anthropogenic) of aerosols and unique topography of the region. In the present study, we have identified different aerosol types using Aerosol Robotic NETwork (AERONET) level 2 aerosol products during 2010-2011 at four different locations in the Indo-Gangetic Basin (IGB) viz. Karachi (24.870N, 67.03 E), Lahore (31.540 N, 74.320 E), Jaipur (26.900 N, 75.900E), and Kanpur (26.4? N, 80.4? E). Five different aerosol types were identified using fine-mode fraction, (FMF) and single scattering albedo (SSA) at the stations over IGB viz. PD (polluted dust), PC (polluted continental), MBC (mostly black carbon), MOC (mostly organic carbon) and NA (non-absorbing). Very interesting results are observed which are discussed in terms of different aerosol types associated with their different optical as well as radiative properties. Keywords: aerosol types, radiative properties, IGB.

  18. Development of the Côte Ivoire Basin: reading provenance, sediment dispersal, and geodynamic implications from heavy minerals

    Science.gov (United States)

    Wozazek, Stefan; Krawinkel, Hannelore

    2002-05-01

    The combined approach of conventional and varietal heavy mineral analysis was applied to constrain changes in source rock area, dispersal routes of detritus, and geodynamic setting of the Upper Cretaceous to Neogene Côte d'Ivoire basin. The heavy mineral assemblage of Albian to Turonian sediments reflect a narrow source rock area and short transport distances. A prominent change in the heavy mineral association of Late Cenomanian to Neogene sediments indicates enlargement of source area and longer fluvial transport distances, or longer storage of sediment within the littoral energy fence. The sudden change within the heavy mineral associations marks the transition from the late syn-rift stage to the early passive margin stage of the Southern Atlantic. During Albian to Late Cenomanian time, the basin geometry was mainly controlled by steep slopes and sediments were transported directly to the depocenter. The situation changed in Late Cenomanian time. A small shelf area developed where sediments from different sources were mixed and reworked before deposition. We believe that the W-E direction of the long-shore drift, which transports today huge quantities of near-shore sand, was established at the end of the Paleogene. This resulted from the drifting of southern West Africa across the paleoequator and subsequent change in surface wind directions.

  19. Multi-Seam Well Completion Technology: Implications for Powder River Basin Coalbed Methane Production

    Energy Technology Data Exchange (ETDEWEB)

    Office of Fossil Energy; National Energy Technology Laboratory

    2003-09-01

    The purpose of this study is to evaluate the potential benefits of applying multiseam [well] completion (MSC) technology to the massive stack of low-rank coals in the Powder River Basin. As part of this, the study objectives are: Estimate how much additional CBM resource would become accessible and technically recoverable--compared to the current practice of drilling one well to drain a single coal seam; Determine whether there are economic benefits associated with MSC technology utilization (assuming its widespread, successful application) and if so, quantify the gains; Briefly examine why past attempts by Powder River Basin CBM operators to use MSC technology have been relatively unsuccessful; Provide the underpinnings to a decision whether a MSC technology development and/or demonstration effort is warranted by DOE. To a great extent, this assessment builds on the previously published study (DOE, 2002), which contains many of the key references that underlie this analysis. It is available on the U.S. Department of Energy, National Energy technology Laboratory, Strategic Center for Natural Gas website (www.netl.doe.gov/scng). It is suggested that readers obtain a copy of the original study to complement the current report.

  20. Seed banks and their implications of rivers with different trophic levels in Chaohu Lake Basin, China.

    Science.gov (United States)

    Cui, Naxin; Wu, Juan; Zhong, Fei; Yang, Lihua; Xiang, Dongfang; Cheng, Shuiping; Zhou, Qi

    2015-02-01

    The seed banks of three rivers, with different trophic levels in Chaohu Lake Basin, China, were investigated to explore the dynamics of seed bank under the pressure of eutrophication. A total of 60 species from 25 family 43 genera were identified from the seed banks of the three rivers. In the eutrophic Paihe River, the species richness and mean seed density were the highest, followed by the oligotrophic Hangbuhe River and the hypereutrophic Nanfeihe River. Various compositions of three functional group assemblage of hydro-ecotypes were found in different rivers. The dominant and endemic species were aquatic, wetland, and terrestrial species in Hangbuhe River, Paihe River, and Nanfeihe River, respectively. The shift trend of seed bank in three rivers probably presented past vegetation dynamics under the trophic process in the rivers of Chaohu Lake Basin. Seed bank in the river bed might be quickly assessed by its trophic level. Additionally, it might imply that the seed bank with more aquatic species in the oligotrophic river would be a potential seed resource for vegetation restoration of severely degraded river ecosystems. PMID:25178861

  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. 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

    Directory of Open Access Journals (Sweden)

    M. S. Pervez

    2014-02-01

    Full Text Available We evaluated the spatial and temporal responses of precipitation in the basins as modulated by the El Niño Southern Oscillation (ENSO and Indian Ocean (IO dipole modes using observed precipitation records at 43 stations across the Ganges and Brahmaputra basins from 1982 to 2010. Daily observed precipitation records were extracted from Global Surface Summary of the Day dataset and spatial and monthly anomalies were computed. The anomalies were averaged for the years influenced by climate modes combinations. Occurrences of El Niño alone significantly reduced (60% and 88% of baseline in the Ganges and Brahmaputra basins, respectively precipitation during the monsoon months in the northwestern and central Ganges basin and across the Brahmaputra basin. In contrast, co-occurrence of La Niña and a positive IO dipole mode significantly enhanced (135% and 160% of baseline, respectively precipitation across both basins. During the co-occurrence of neutral phases in both climate modes (occurring 13 out of 28 yr, precipitation remained below average to average in the agriculturally extensive areas of Haryana, Uttar Pradesh, Bihar, eastern Nepal, and the Rajshahi district in Bangladesh in the Ganges basin and northern Bangladesh, Meghalaya, Assam, and Arunachal Pradesh in the Brahmaputra basin. This pattern implies that a regular water deficit is likely in these areas with implications for the agriculture sector due to its reliance on consistent rainfall for successful production. Major flooding and drought occurred as a consequence of the interactive effects of the ENSO and IO dipole modes, with the sole exception of extreme precipitation and flooding during El Niño events. 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 changing climate.

  3. 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.

  4. Gravity and magnetic investigations in the Haouz basin, Morocco. Interpretation and mining implications

    Science.gov (United States)

    Jaffal, Mohammed; El Goumi, Najib; Kchikach, Azzouz; Aïfa, Tahar; Khattach, Driss; Manar, Ahmed

    2010-09-01

    The Marrakech region is known for its significant mining potential concealed by the Hercynian basement. In order to extend the exploration of this basement beyond its outcrops in the Jebilets and Guemassa massifs, we used magnetic and gravity data from a sub-area in the Haouz basin. Our methodology in this study consists of processing the data, so as to highlight the buried geological contacts and to reveal their dips. The study of the geological contacts is ensured by the upward continuation processing of the residual gravity map at various altitudes, followed by the determination of the horizontal gradient maxima for each level. The progressive migration of these maxima while increasing the upward continuation altitude indicates the dip direction. The structures deduced from gravity are superimposed on the magnetic map in order to emphasize their possible association with magnetic sources. Comparison between gravity anomalies and local geology shows that these anomalies are mainly caused by basement topography undulations. Moreover, lows coincide with granite and thick sedimentary depressions while highs coincide with basement outcrops. The local maxima of the horizontal gradient of the residual gravity data and its upward continuation at various altitudes define a field of features, organized into groups oriented both NE-SW and NW-SE, which correspond to the regional Hercynian structures. Moreover, the main highlighted lineaments coincide perfectly with known fractures such as the North-Atlas and the Guemassa faults whose dip and direction are well documented. These detected features allow us to complete and enrich the structural map of the Haouz basin. A joint detailed analysis of the mapped gravity contacts and the magnetic data was carried out, through the use of Magnetic and Gravity Euler Trends in terms of depth and rooting, taking into account the local geology, to identify potential structures for mining exploration.

  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. Late Badenian foraminifers from the Vienna Basin (Central Paratethys): stable isotope study and paleoecological implications

    Science.gov (United States)

    Ková?ová, Patrícia; Hudá?ková, Natália

    2009-02-01

    Paleoecological interpretations based on stable isotope study of benthic (Uvigerina semiornata) and planktonic (Globigerina bulloides, Globigerinoides trilobus) foraminiferal shells from the Paratethys Vienna Basin (southwestern Slovakia) are presented. The study was performed on sediments of the Devínska Nová Ves-clay pit deposited during the Middle and Late Badenian (Middle Miocene). Our ?13C data show an enhanced nutrient input to the water column and the organic matter accumulation at the bottom of the Vienna Basin. The remineralization of accumulated organic matter on the sea floor resulted in the formation of oxygen-depleted zones, where no oxic indicators but the oxygen-deficiency tolerant species were found. Positive benthic ?18O signal can be attributed to the influence of the global cooling recognized in the world-ocean during the Middle Miocene. At the same time, variations observed in the water column are interpreted as reflecting the local temperature and salinity changes resulting from the fluvial and rain inflow. The differences between surface and bottom water temperature reflect the stratification of the water column. Such stratification might be related to the isolation process of Central Paratethys in the Badenian. This study confirms that ?13C and ?18O are not always in isotopic equilibrium with the ambient water but are also influenced by vital effects (respiration, symbiont photosynthesis …). The vital effects led to the incorporation of isotopically light metabolic CO2 into Globigerina bulloides resulting in high similarity between ?13C values of Uvigerina and Globigerina. It has been shown that the extremely high ?13C and very low ?18O of Globigerinoides trilobus clearly imply the influence of algal photosymbionts.

  7. 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.

  8. Seismic stratigraphy of the central South China Sea basin and implications for neotectonics

    Science.gov (United States)

    Li, Chun-Feng; Li, Jiabiao; Ding, Weiwei; Franke, Dieter; Yao, Yongjian; Shi, Hesheng; Pang, Xiong; Cao, Ying; Lin, Jian; Kulhanek, Denise K.; Williams, Trevor; Bao, Rui; Briais, Anne; Brown, Elizabeth A.; Chen, Yifeng; Clift, Peter D.; Colwell, Frederick S.; Dadd, Kelsie A.; Hernández-Almeida, Iván.; Huang, Xiao-Long; Hyun, Sangmin; Jiang, Tao; Koppers, Anthony A. P.; Li, Qianyu; Liu, Chuanlian; Liu, Qingsong; Liu, Zhifei; Nagai, Renata H.; Peleo-Alampay, Alyssa; Su, Xin; Sun, Zhen; Tejada, Maria Luisa G.; Trinh, Hai Son; Yeh, Yi-Ching; Zhang, Chuanlun; Zhang, Fan; Zhang, Guo-Liang; Zhao, Xixi

    2015-03-01

    Coring/logging data and physical property measurements from International Ocean Discovery Program Expedition 349 are integrated with, and correlated to, reflection seismic data to map seismic sequence boundaries and facies of the central basin and neighboring regions of the South China Sea. First-order sequence boundaries are interpreted, which are Oligocene/Miocene, middle Miocene/late Miocene, Miocene/Pliocene, and Pliocene/Pleistocene boundaries. A characteristic early Pleistocene strong reflector is also identified, which marks the top of extensive carbonate-rich deposition in the southern East and Southwest Subbasins. The fossil spreading ridge and the boundary between the East and Southwest Subbasins acted as major sedimentary barriers, across which seismic facies changes sharply and cannot be easily correlated. The sharp seismic facies change along the Miocene-Pliocene boundary indicates that a dramatic regional tectonostratigraphic event occurred at about 5 Ma, coeval with the onsets of uplift of Taiwan and accelerated subsidence and transgression in the northern margin. The depocenter or the area of the highest sedimentation rate switched from the northern East Subbasin during the Miocene to the Southwest Subbasin and the area close to the fossil ridge in the southern East Subbasin in the Pleistocene. The most active faulting and vertical uplifting now occur in the southern East Subbasin, caused most likely by the active and fastest subduction/obduction in the southern segment of the Manila Trench and the collision between the northeast Palawan and the Luzon arc. Timing of magmatic intrusions and seamounts constrained by seismic stratigraphy in the central basin varies and does not show temporal pulsing in their activities.

  9. Reconstruction of the Mesozoic subduction in the South China Sea and its implications on the opening of the South China Sea basins

    Science.gov (United States)

    Li, F.; Sun, Z.; Yang, H.

    2013-12-01

    Reconstruction of the Mesozoic subduction system in the South China Sea (SCS) can improve our understanding of the tectonic evolution in the region and holds important implications on the opening of the SCS basins. Here we report the locations of the Mesozoic volcanic arc and trench in the SCS based on satellite-derived magnetic and gravimetric data, as well as drilling data from the China National Offshore Oil Corporation. The magnetic data allows us to identify the volcanic arc, which is characterized as high positive magnetic anomaly (HPMA) due to serpentinization. Furthermore, the volcanic arc is verified by distributions of intermediate rocks that are determined from the drilling data. The gravimetric data is used to determine the locations of the Mesozoic trench. Our preliminary results show two distinct HPMA belts along the two sides of the SCS basins. The first one locates northwest to the ridge axis of the SCS basins and extends from Taiwan in the northeast to the Xisha Island in the southwest. The second one locates on the Nansha-Dangerous Ground, southeast to the opening axis of the southwest sub-basin of the SCS, and is nearly parallel to the orientation of the first one. In addition, the distribution of intermediate rocks within the two HPMA belts indicates that the two belts represent the present locations of the Mesozoic volcanic arc. Furthermore, we recognize the corresponding Mesozoic trench by peak gross horizontal gradient of bouguer gravity anomaly in the northeastern SCS. It is located northwest to the ridge axis of the SCS basins and southeast to the Mesozoic arc. Moreover, drilling sample MZ-1-1 from the area between the Mesozoic arc and trench has shown clear signatures of forearc basin sediments, providing additional support to our arc and trench locations. Based on the opening direction of the SCS basins, we interpret that the two HPMA belts belong to the same Mesozoic volcanic arc that is located on the Eurasia continental crust. The arc was formed by the northwestward subduction of the Izanagi and Pacific plates beneath the Eurasia plate. The current locations of the Mesozoic arc indicate that it was separated by the opening of the SCS basins. In addition, the opening of the SCS basins may obliquely cut the proto-SCS oceanic crust in the northeast and the Eurasia continental crust in the southwest. Thus, the southwest segment of the Mesozoic arc is carried to the Nansha-Dangerous Ground, southeast to the ridge axis of the southwest sub-basin of the SCS. In comparison, the northeast portion of the Mesozoic subduction system is located northwest to the ridge axis of the SCS basins.

  10. Fracturing of doleritic intrusions and associated contact zones: Implications for fluid flow in volcanic basins

    Science.gov (United States)

    Senger, Kim; Buckley, Simon J.; Chevallier, Luc; Fagereng, Åke; Galland, Olivier; Kurz, Tobias H.; Ogata, Kei; Planke, Sverre; Tveranger, Jan

    2015-02-01

    Igneous intrusions act as both carriers and barriers to subsurface fluid flow and are therefore expected to significantly influence the distribution and migration of groundwater and hydrocarbons in volcanic basins. Given the low matrix permeability of igneous rocks, the effective permeability in- and around intrusions is intimately linked to the characteristics of their associated fracture networks. Natural fracturing is caused by numerous processes including magma cooling, thermal contraction, magma emplacement and mechanical disturbance of the host rock. Fracturing may be locally enhanced along intrusion-host rock interfaces, at dyke-sill junctions, or at the base of curving sills, thereby potentially enhancing permeability associated with these features. In order to improve our understanding of fractures associated with intrusive bodies emplaced in sedimentary host rocks, we have investigated a series of outcrops from the Karoo Basin of the Eastern Cape province of South Africa, where the siliciclastic Burgersdorp Formation has been intruded by various intrusions (thin dykes, mid-sized sheet intrusions and thick sills) belonging to the Karoo dolerite. We present a quantified analysis of fracturing in- and around these igneous intrusions based on five outcrops at three individual study sites, utilizing a combination of field data, high-resolution lidar virtual outcrop models and image processing. Our results show a significant difference between the three sites in terms of fracture orientation. The observed differences can be attributed to contrasting intrusion geometries, outcrop geometry (for lidar data) and tectonic setting. Two main fracture sets were identified in the dolerite at two of the sites, oriented parallel and perpendicular to the contact respectively. Fracture spacing was consistent between the three sites, and exhibits a higher degree of variation in the dolerites compared to the host rock. At one of the study sites, fracture frequency in the surrounding host rock increases slightly toward the intrusion at approximately 3 m from the contact. We conclude by presenting a conceptual fluid flow model, showing permeability enhancement and a high potential for fluid flow-channeling along the intrusion-host rock interfaces.

  11. 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.

  12. Localized Stress Perturbations in the Northern Newark Basin: Implications for Induced Seismicity and Carbon Sequestration

    Science.gov (United States)

    Zakharova, N. V.; Goldberg, D.

    2013-12-01

    Induced seismicity has emerged as one of the primary concerns for large-volume underground injections, such as wastewater disposal and carbon sequestration. In order to mitigate potential seismic risks, detailed knowledge of reservoir geometry, occurrence of faults and fractures, and the distribution of in situ stresses is required to predict the effect of pore pressure increase on formation stability. We present a detailed analysis of in situ stress distribution at a potential carbon sequestration site in the northern Newark basin, and then consider fault and fracture stability under injection conditions taking into account the effects of localized stress perturbations, formation anisotropy and poroelasticity. The study utilizes borehole geophysical data obtained in a 2-km-deep well drilled into Triassic lacustrine sediments in Rockland County, NY. A complex pattern of local variations in the stress field with depth and at multiple scales is revealed by borehole breakouts, including: (i) gradual counter-clockwise rotation of horizontal stress orientation and decrease in relative magnitude with depth, (ii) pronounced rotations of the principal horizontal stresses at two depths, ~800 m and ~1200 m, and (iii) small-scale departures from mean orientation at the scale of meters to tens of meters. Localized stress drop near active faults may explain these observations. Seismic profiling in the vicinity of the borehole and along dip and strike of basin sediments suggests the presence of crosscutting, and potentially active, fault zones but their geometry cannot be accurately resolved. Borehole image data from the site indicates the presence of numerous fractures with increasing density over depth that roughly form two sets: high-angle fractures striking NE-SW and sub-horizontal fractures dipping NW. We perform iterative dislocation modeling for various fault orientations and slip distances to match the observed stress distribution in the borehole. Both intersecting and non-intersecting faults are modeled. Uncertainties introduced by unknown compressive rock strength and heterogeneous lithology are addressed using multivariate statistical analysis of the acquired log data, including elastic wave anisotropy. Our preliminary results suggest that shallow reservoirs ( 1.2 km) may allow injection with up to 15 MPa pore pressure increase before the effective stress reaches the failure limit on critical faults.

  13. Textural and geochemical characteristics of the Ajali Sandstone, Anambra Basin, SE Nigeria: Implication for its provenance

    Science.gov (United States)

    Tijani, Moshood Niyi; Nton, Matthew Essien; Kitagawa, Ryuji

    2010-02-01

    This study presents the mineralogical, textural and geochemical characteristics of the regional Maastrichtian Ajali Sandstone in Anambra Basin, SE Nigeria. The intent is to highlight possible constraints on the chemical weathering conditions of the source materials on one hand, and to infer the provenance on the other hand. The investigation approach involved field studies and collection of samples from 12 different outcrop locations, followed by laboratory studies involving grain-size analysis (GSA), major and trace elements analyses using the X-ray fluorescence (XRF) method as well as thin section petrography. Field studies show that the sandstones are friable at all locations and range in color from white in freshly cut stone, to reddish brown on weathering. In addition, the sandstone units are cross-bedded and show graded bedding exemplified by fining upward sequence. Textural examination indicates that the sandstones range from fine to medium sands, constituting about 76 to 99% sand fraction, with graphic mean grain size of 0.23 to 0.53 mm. Standard deviation (sorting) ranges from 0.56 to 1.24 Ø and implies moderately well sorted sediments. Inferred from the textural indices, the depo-environmental discrimination of the Ajali Sandstone revealed a fluvial/river system-dominated sedimentary process. The sandstones are quartz arenite with quartz greater than 90% and less than 5% K-feldspar which indicate a predominant basement source as also revealed by the heavy mineral assemblages. In addition, major elemental oxides shows SiO 2 content greater than 96% for the fresh Ajali Sandstone samples with extreme depletion of mobile oxides such as Na 2O, CaO and the ferromagnesian minerals through weathering and sedimentary processes. Provenance and tectonic setting discrimination using geochemical data and compositional maturity revealed typical felsic igneous-dominated cratonic environment while inter-elemental ratios (such as Zr/Cr, Y/Ni, Th/Sc, La/Sc and La/Co) and ternary plots (e.g. Th-Sc-Zr; La-Th-Sc and Th-Co-Zr) reflect passive continental margin setting for the Ajali Sandstone. Consequently, the source area is constrained to the Precambrian basement rock units of Adamawa-Oban massif areas to the east of the Anambra Basin and the adjacent Abakaliki Anticlinorium.

  14. 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.

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

    Directory of Open Access Journals (Sweden)

    Stojanovi? Ksenija

    2012-01-01

    Full Text Available 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, Podocarpaceae, Cupressaceae, Araucariaceae, Phyllocladaceae and Pinaceae. Peatification was performed in neutral to slightly acidic, fresh water environment. Considering that organic matter of Drmno lignites was deposited at the same time, in the relatively constant climate, it could be supposed that climate probably had only small impact on peatification. Therefore, variations in compositions of macerals and biomarkers indicate changes in the water level, due to seasonal drying of the mire, which caused vegetation differences in the palaeoplant communities and changes of redox conditions (from anoxic to slightly oxic during peatification. Diagenetic transformations of the organic matter were mainly governed by microbial activity, rather than thermal alteration.

  16. 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.

  17. Community Perception on Lake Victoria Basin Resources Degradation: Implications to Sustainable Management

    Directory of Open Access Journals (Sweden)

    Albino J. M. Tenge

    2015-02-01

    Full Text Available Degradation of Lake Victoria Basin (LVB resources due to deforestation, illegal fishing and unsustainable farming practices is among the major challenge to the natural resources managers and the livelihood of surrounding communities. Several measures have been proposed to mitigate the situation. These measures range from policies, laws, regulations to technical options. Despite these efforts, adherence to these regulations and adoption of the proposed technologies is low. Among the factors that can influence household adoption of a particular technology is perception of the problem and the technology itself. This has not been thoroughly investigated and integrated in development and promotion of mitigation options. This research assessed the local community perception on the LVB resources, levels of degradation and the causes. The research was done in selected sites within LVB in Tanzania, Uganda and Rwanda. Data was collected through questionnaire interviews and focused group discussion to 334 respondents. Collected data was descriptively analyzed using means, frequencies, percentages and ranking. Results indicate that majority of community members perceive LVB resources to be currently more degraded than past twenty years. However, specific types of resources and levels of degradation do differ between countries. Degradation factors are personal, administrative, technical and policy related. Lack of alternatives is among the major driving forces to degradation activities. It is recommended that intervention efforts to reverse degradation situation need to consider local community perception and be of multiple nature to address technical, administrative and policy issues.

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

    Science.gov (United States)

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

    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 a-value, b-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 b-value is 1.05, which indicates that the earthquake occurred due to active tectonics in the region. The three dimensional b-value mapping shows that a high b-value region is sandwiched around the 2001 Bhuj mainshock hypocenter at depths of 20-25 km between two low b-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.

  19. 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.

  20. 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.

  1. Objective Identification of Atmospheric Rivers, and Implications for Extreme Precipitation at the Basin Scale

    Science.gov (United States)

    Hughes, M.; Jackson, D. L.; Wick, G. A.; Gutmann, E. D.

    2014-12-01

    Atmospheric rivers (ARs) are narrow, filamentary structures of water vapor in the atmosphere often present in the warm sector of extratropical cyclones. ARs were present and were an important contributor to major flooding events along the U.S. west coast. However, several aspects of the complete relationship between ARs and flooding events remain uncertain. Given the infrequent nature of flooding events, a long time series of ARs, orographic precipitation processes, and flood occurrence is required to yield statistically robust results characterizing conditions necessary to lead to significant precipitation. This project analyzes the mesoscale to synoptic processes relevant for controlling extreme precipitation from atmospheric rivers at the regional scale, crucial for decision making about disaster planning and water budgeting in a changing climate system. First, a 30-year catalog of atmospheric rivers is constructed with an objective identification tool applied to the Climate Forecast System Reanalysis. A complementary catalog of extreme precipitation events across California is then identified in gridded daily observation-based data. Synoptic characteristics of the subset of these atmospheric rivers that are extreme-precipitation-producing are compared against similar statistics for non-extreme-precipitation-producing atmospheric rivers. A subset of both extreme and non-extreme events are then investigated in high resolution regional climate model simulations generated with the Weather Research and Forecast model run at 6km horizontal grid spacing across California. These model simulations are compared to results from two other models of varying complexity, including a simple linear model of orographic precipitation and a simplified dynamical weather model. The high-resolution model simulations will help identify the mesoscale processes responsible for determining basin-scale response to the larger-scale water vapor fluxes associated with atmospheric rivers, as well as the model complexity necessary to properly represent these processes. The latter results will be used to inform a future experiment downscaling atmospheric rivers in global climate model output.

  2. Analysis of Repeating Events and Implications for Fault Zone Behavior Beneath the Aceh Basin, Northern Sumatra

    Science.gov (United States)

    Barrett, S. A.; Ammon, C. J.

    2010-12-01

    The 2004 Sumatra-Andaman Islands megathrust earthquake, one of the largest seismic events on record, initiated a substantial sequence of aftershocks that includes a number of intriguing repeating earthquakes. These events provide important insight into the nature of post-seismic deformation and to the character of repeating earthquakes. To explore post-event deformation, and asperity behavior deep along the subduction plate boundary zone, we examine eight clusters of repeating events that occurred beneath the Aceh Basin between 26 December 2004 and 31 December 2010 and for which short-period teleseismic P waveforms correlate (within clusters) at a 95% or greater level. One unusual aspect of these events is their large size (Mw between 5.1 and 6.0) that allows detection and analysis using regional and teleseismic observations. Analysis of regional short period coda suggests that most are within a few hundred meters of one another indicating repeated failure of the same asperity. We believe that these repeating events occur on frictionally unstable asperities surrounded by much larger aseismically deforming regions. Events within a given cluster, exhibit the expected increase in recurrence interval with time since the mainshock that one would expect from failure driven by post-seismic deformation. Curiously, the events in most clusters show a decrease in magnitude with time, despite the increasing hold time between the events. We attribute the decrease in moment to the ongoing reduction in regional strain rate, prompting either a change in the frictional strength of the asperity or a decrease in the asperity area. Our analysis suggests that work on repeating events within aftershock sequences could be preformed using stations at teleseismic and far regional distances.

  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. 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 interme 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)

  5. 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, Bin; Wang, Liangshu; Dong, Ping; Wu, YongJing; Li, Changbo; Hu, Bo; Wang, Chong

    2012-11-01

    The Hailar Basin is one of the typical basins among the NE China Basin Groups, 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 magnetic, gravity, petrophysical, geothermal and seismological data, we separate the Gravity and Magnetic Anomalies (GMA) into four orders using Wavelet Multi-scale Decomposition (WMD). The apparent depths of causative sources were then assessed by Power Spectrum Analysis (PSA) of each order. Low-order wavelet detail anomalies were used to study the basin's basement structure such as major faults, the basement lithology, uplifts and depressions. High-order ones were used for the inversion of Moho and Curie discontinuities using the Parker method. The results show that the Moho uplifting area of the Hailar Basin is located at the NE part of the basin, the Curie uplifting area is at the NW part, and neither of them is consistent with the basin's sedimentary center. This indicates that the Hailar Basin may differ in basin building pattern from other middle and eastern basins of the basin groups, and the Hailar Basin might be of a passive type. When the Pacific Plate was subducting to NE China, the frontier of the plate lying on the mantle transition zone didn't pass through the Great Khingan Mountains region, so there is not an obvious magma upwelling or lithospheric extension in the Hailar Basin area. Finally, based on the seismological data and results of WMD, a probable 2D crust model is derived from an across-basin profile using the 2D forward modeling of the Bouguer gravity anomaly. The results agree with those from seismic inversion, suggesting WMD is suitable for identifying major crustal density interfaces.

  6. 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.

  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, 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.

  8. 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.

  9. Enriched back-arc basin basalts from the northern Mariana Through: Implications for the magmatic evolution of back-arc basins

    International Nuclear Information System (INIS)

    The composition of basalts erupted at the earliest stages in the evolution of back-arc basin permit unique insights into the composition and structure of the sub-arc mantle. We report major and trace element chemical data and O-, Sr-, Nd-, and Pb-isotopic analyses for basalts recovered from four dredge hauls and one ALVIN dive in the northern Mariana Trough near 22deg N. The petrography and major element chemistry of these basalts (MTB-22) are similar to tholeiites from the widest part of the Trough, near 18deg N (MTB-18), except that MTB-22 have slightly more K2O and slightly less TiO2. The trace element data exhibit a very strong arc signature in MTB-22, including elevated K, Rb, Sr, Ba, and LREE contents; relatively low K/Ba and high Ba/La and Sr/Nd. The Sr- and Nd-isotopic data plot in a field displaced from that of MTB-18 towards Mariana arc lavas, and the Pb-isotopic composition of MTB-22 is indistinguishable from Mariana arc lavas and much more homogeneous than MTB-18. Mixing of 50-90% Mariana arc component with a MORB component is hypothesized. We cannot determine whether this resulted from physical mixing of arc mantle and MORB mantle, or whether the arc component is introduced by metasomatism of MORB-like mantle by fluids released from the subducted lithosphere. The strong arc signature in back-arc melts from the Mariana Trough at 22deg N, where the back-arc basin is narrow, supports general models for back-arc basin evolution whereby eels for back-arc basin evolution whereby early back-arc basin basalts have a strong arc component which diminishes in importante relative to MORB as the back-arc basin widens. (orig.)

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

    OpenAIRE

    Simon Weides; Jacek Majorowicz

    2014-01-01

    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 de...

  11. 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

    OpenAIRE

    Abubakar Mijinyawa; Bhattacharya, S. K.; A. Moumouni; S. Mijinyawa; Ibad Mohammad

    2013-01-01

    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 150-30...

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

    Science.gov (United States)

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

    2014-05-01

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

  13. Stratigraphy, Sequence, and Crater Populations of Lunar Impact Basins from Lunar Orbiter Laser Altimeter (LOLA) Data: Implications for the Late Heavy Bombardment

    Science.gov (United States)

    Fassett, C. I.; Head, J. W.; Kadish, S. J.; Mazarico, E.; Neumann, G. A.; Smith, D. E.; Zuber, M. T.

    2012-01-01

    New measurements of the topography of the Moon from the Lunar Orbiter Laser Altimeter (LOLA)[1] provide an excellent base-map for analyzing the large crater population (D.20 km)of the lunar surface [2, 3]. We have recently used this data to calculate crater size-frequency distributions (CSFD) for 30 lunar impact basins, which have implications for their stratigraphy and sequence. These data provide an avenue for assessing the timing of the transitions between distinct crater populations characteristic of ancient and young lunar terrains, which has been linked to the late heavy bombardment (LHB). We also use LOLA data to re-examine relative stratigraphic relationships between key lunar basins.

  14. Tectono-stratigraphy of the Neogene basins in Western Turkey: Implications for tectonic evolution of the Aegean Extended Region

    Science.gov (United States)

    Ersoy, E. Y.; Çemen, ?.; Helvac?, C.; Billor, Z.

    2014-11-01

    The western part of the Aegean region includes several Neogene basins containing volcano-sedimentary successions. The Neogene basins, located along the northern Menderes Extensional Metamorphic Complex (MEMC) were developed during the Miocene as supra-detachment basins. They contain two distinct volcano-sedimentary successions, separated by a regional unconformity. The basins located to the west of the MEMC were developed as strike-slip basins and contain volcanic and sedimentary units getting younger from NE to SW with no remarkable unconformity. Available paleomagnetic studies in the Aegean Region suggest to us that, the basins to the west of the MEMC were developed in response to southward clockwise rotational roll-back of the Aegean subduction zone. The eastern margin of this rotational deformation is characterized on the surface by a large strike-slip zone, which is known as ?zmir-Bal?kesir Transfer Zone (?BTZ). The sedimentary successions in the basins along the northern MEMC do not show southward younging and are interpreted to be developed in response to exhumation of the MEMC. During the Pliocene to Quaternary, ~ E-W-trending grabens such as the Gediz (Ala?ehir), Büyük and Küçük Menderes Grabens were developed in response to tectonic escape accompanying the slab-roll back process. These grabens truncate the MEMC basins. During this time, strike-slip deformation and associated sedimentation continued along the ?BTZ.

  15. Regional patterns of magnetite authigenesis in the Appalachian Basin: Implications for the mechanism of Late Paleozoic remagnetization

    Science.gov (United States)

    McCabe, Chad; Jackson, Michael; Saffer, Barbara

    1989-08-01

    We report paleomagnetic and rock magnetic data from sedimentary carbonates of the Appalachian Basin that have implications for the mechanism of widespread late Paleozoic remagnetization in this rock type. Sampling was accomplished mostly along two across-basin transects, one in Devonian carbonates of New York State and the other in Ordovician and Mississippian carbonates of Tennessee and Alabama. Paleomagnetic investigations of the New York Devonian carbonates along a transect from Albany to Buffalo indicate that these rocks were completely remagnetized in Alleghenian time. Rock magnetic studies show that magnetite concentration varies in a regular fashion along the transect with a local maximum near Syracuse and decreasing gradually to the east and west. This pattern shows a striking correlation with the degree of diagenetic alteration of clay minerals in a Devonian bentonite horizon which took place during Alleghenian time. We conclude that most of the magnetite present in these carbonates is of authigenic origin and that clay mineral alteration and magnetite authigenesis were coeval, late Paleozoic events that were controlled by the same diagenetic factors. Thermoviscous remagnetization processes cannot be ruled out in this setting in light of the observed degree of thermal maturity. However, our results suggest that chemical factors played a critical role in remagnetization since they allow us to infer that magnetite authigenesis and remagnetization are about the same age. We propose a geochemical model for magnetite authigenesis wherein the iron is derived from detrital smectites during diagenetic illitization, which is triggered by the introduction of potassium-rich brines. Results from the Tennessee transect from Nashville to Chattanooga show a very different pattern. Paleomagnetic studies indicate that late Paleozoic remagnetization has affected Ordovician carbonates of the Nashville Dome. Paleozoic carbonates in the overthrust belt near Chattanooga also carry the late Paleozoic remagnetization. However, Mississippian carbonates between the dome and the overthrust belt are very weakly magnetized and show no evidence for late Paleozoic remagnetization. Samples show only a present field magnetization or, at one locality in northwestern Alabama, a dual-polarity magnetization of probable Mississippian age. Rock magnetic studies indicate that higher concentrations of magnetite are present in the remagnetized rocks of the Nashville Dome and the overthrust belt than in the nonremagnetized Mississippian carbonates. We therefore conclude that magnetite authigenesis and remagnetization are related events in this setting and that the remagnetization must be due to chemical processes. The presence of a remagnetization "shadow" in the younger rocks now exposed between the fold-thrust belt and the flexural arch is attributed to westward flow of magnetite-forming aqueous fluids through deep, sub-Carboniferous aquifers during Alleghenian time. Upward migration of the fluids through the Mississippian carbonates may have been prevented by the Devono-Mississippian Chattanooga Shale, an impermeable stratum that is present throughout the region.

  16. 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.

  17. 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.

  18. Hydrological Controls of Riverine Ecosystems of the Napo River (Amazon Basin): Implications for the Management and Conservation of Biodiversity

    Science.gov (United States)

    Celi, J. E.; Hamilton, S. K.

    2013-12-01

    Scientific understanding of neotropical floodplains comes mainly from work on large rivers with predictable seasonal flooding regimes. Less studied rivers and floodplains on the Andean-Amazon interface are distinct in their hydrology, with more erratic flow regimes, and thus ecological roles of floodplain inundation differ in those ecosystems. Multiple and unpredictable flooding events control inundation of floodplains, with important implications for fish and wildlife, plant communities, and human activities. Wetlands along the river corridor exist across a continuum from strong river control to influence only by local waters, with the latter often lying on floodplain paleoterraces. The goal of this study was to understand the hydrological interactions and habitat diversity of the Napo River, a major Amazon tributary that originates in the Andes and drains exceptionally biodiverse Andean foreland plains. This river system is envisioned by developers as an industrial waterway that would require hydrological alterations and affect floodplain ecosystems. Water level regimes of the Napo River and its associated environments were assessed using networks of data loggers that recorded time under water across transects extending inland from the river across more than 100 sites and for up to 5 years. These networks also included rising stage samplers that collected flood water samples for determination of their origin (i.e., Andean rivers vs. local waters) based on hydrochemical composition. In addition, this work entails a classification of aquatic environments of the Napo Basin using an object-oriented remote sensing approach to simultaneously analyze optical and radar satellite imagery and digital elevation models to better assess the extent and diversity of flooded environments. We found out a continuum of hydrological regimes and aquatic habitats along the Napo River floodplains that are linked to the river hydrology in different degrees. Overall, environments that are proximal or that have high hydrological connectivity are riverine controlled versus systems that are distal or that have less or no connectivity that rely on rainwater or local runoff as a source of flooding. Outcomes of this research gave us insight on the extent and diversity of aquatic habitats of the Napo River, the role that the river has on their ecohydrology, the potential effects of different hydrologic scenarios on these ecosystems, and the management measures that need to be considered to support conservation in the region.

  19. Mineralogy of the Mafic Anomaly in the South Pole-Aitken Basin: Implications for excavation of the lunar mantle

    Science.gov (United States)

    Pieters, C. M.; Tompkins, S.; Head, J. W.; Hess, P. C.

    1997-01-01

    Mineralogy of South Pole-Aitken Basin (SPA) (the largest confirmed impact basin on the Moon) is evaluated using five-color images from Clementine. Although olivine-rich material as well as basalts rich in clinopyroxene are readily identified elsewhere on the farside, the dominant rock type observed across the interior of SPA is of a very noritic composition. This mineralogy suggests that lower crust rather than the mantle is the dominant source of the mafic component at SPA. The lack of variation in observed noritic composition is probably due to basin formation processes, during which extensive melting and mixing of target materials are likely to occur.

  20. 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 easternne 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

  1. U-Pb zircon ages from the southwestern Karoo Basin, South Africa - Implications for the Permian-Triassic boundary

    Science.gov (United States)

    Fildani, A.; Weislogel, A.; Drinkwater, N.J.; McHargue, T.; Tankard, A.; Wooden, J.; Hodgson, D.; Flint, S.

    2009-01-01

    U-Pb ages determined using sensitive high-resolution ion microprobe-reverse geometry on 205 single-grain zircons from 16 ash beds within submarine fan deposits of the Ecca Group provide the first evidence of a marine Permian-Triassic (P-T) boundary in the Karoo Basin of South Africa. These U-Pb ages provide an objective basis for correlating the deep-marine sediments of the southwest Karoo Basin with fluvial-deltaic deposits in the central and eastern parts of the basin where the P-T boundary is recorded in a diverse macrofauna. Furthermore, these new zircon ages and their correlation imply asymmetric subsidence and variable sedimentation rates across the basin. ?? 2009 Geological Society of America.

  2. Stratigraphic variations across the Marañón Fold-Thrust Belt, Peru: Implications for the basin architecture of the West Peruvian Trough

    Science.gov (United States)

    Scherrenberg, Arne F.; Jacay, Javier; Holcombe, Rodney J.; Rosenbaum, Gideon

    2012-10-01

    Basin inversion has played a major role in the structural evolution of the Andean Orogeny. We present new observations from the Marañón Fold-Thrust Belt (MFTB) in central Peru that show Cretaceous facies changes and thickness variations that may have been controlled by a series of faults in the basement of the West Peruvian Trough (WPT), separating this basin into smaller sub-basins. We present three new stratigraphic columns and a revised geological map, highlighting stratigraphic relationships within the MFTB. Our results show that a major boundary exists within the MFTB, across which stratigraphic units show distinct facies and thickness changes. This boundary is a long-lived intrabasinal structure (Chonta Fault), and its palinspastic reconstruction is of a half-graben geometry, with the graben floors tilted to the east. Our results indicate that the architecture of the WPT in central Peru during the Late Cretaceous may have been made up of three relatively small basins.

  3. Population genetic analysis of Arapaima gigas, one of the largest freshwater fishes of the Amazon basin : implications for its conservation

    OpenAIRE

    Hrbek, Tomas; Izeni P. Farias; Crossa, Marcelo; Sampaio, Iracilda; Jorge I. R. Porto; Meyer, Axel

    2005-01-01

    The present study reports the first population genetic analysis of Arapaima gigas, an important but critically over-exploited fish species of the Amazon basin. We sequenced two discontinuous mitochondrial DNA regions of 1204 base-pairs (bp) (NADH1 segment) and 1143 bp (ATPase segment) from 139 individuals of A. gigas representing eight localities spanning the Amazon basin from Iquitos, Peru to Macap´a, Brazil. We discovered 34 haplotypes separated by 44 segregating sites. The two most common ...

  4. 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.

  5. 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 diide-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)

  6. 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.

  7. Paleocene-Eocene potential source rocks in the Avengco Basin, Tibet: Organic geochemical characteristics and their implication for the paleoenvironment

    Science.gov (United States)

    Han, Zhongpeng; Xu, Ming; Li, Yalin; Wei, Yushuai; Wang, Chengshan

    2014-10-01

    The Avengco Basin is located in the western part of the Tibetan Plateau and is similar to the Nima Basin in the central part of the plateau and the Lunpola Basin in the eastern part in terms of sedimentary characteristics and tectonic settings, which are well known to provide a good source rock potential. However, the organic geochemical characteristics of the Paleocene-Eocene potential source rocks in the Avengco Basin have been under debate. Thirty-four marl and mudstone outcrop samples of the Niubao Formation in the Avengco Basin were collected and subjected to the following analyses: total organic carbon (TOC), Rock-Eval pyrolysis, stable carbon isotopes of kerogen, gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). Here, we present the results indicating the organic matter of the upper Niubao Formation is mainly composed of Type II kerogen with a mixed source, which is dominated by algae. However, the lower Niubao Formation has the less oil-prone Type II-III kerogen, and the sources of the organic matter are mainly terrestrial plants with less plankton. In addition, the samples are thermally immature to marginally mature. The Niubao Formation was deposited in an anoxic-oxic environment which was brackish with an imperceptible stratified water column. The upper Niubao Formation has a medium to good hydrocarbon-generating potential. However, the lower Niubao Formation has a zero to poor hydrocarbon-generating potential.

  8. 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.

  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. Procedure for calculating estimated ultimate recoveries of Bakken and Three Forks Formations horizontal wells in the Williston Basin

    Science.gov (United States)

    Cook, Troy A.

    2013-01-01

    Estimated ultimate recoveries (EURs) are a key component in determining productivity of wells in continuous-type oil and gas reservoirs. EURs form the foundation of a well-performance-based assessment methodology initially developed by the U.S. Geological Survey (USGS; Schmoker, 1999). This methodology was formally reviewed by the American Association of Petroleum Geologists Committee on Resource Evaluation (Curtis and others, 2001). The EUR estimation methodology described in this paper was used in the 2013 USGS assessment of continuous oil resources in the Bakken and Three Forks Formations and incorporates uncertainties that would not normally be included in a basic decline-curve calculation. These uncertainties relate to (1) the mean time before failure of the entire well-production system (excluding economics), (2) the uncertainty of when (and if) a stable hyperbolic-decline profile is revealed in the production data, (3) the particular formation involved, (4) relations between initial production rates and a stable hyperbolic-decline profile, and (5) the final behavior of the decline extrapolation as production becomes more dependent on matrix storage.

  11. Quality and age of shallow groundwater in the bakken formation production area, williston basin, montana and north dakota.

    Science.gov (United States)

    McMahon, P B; Caldwell, R R; Galloway, J M; Valder, J F; Hunt, A G

    2015-04-01

    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 (14) C 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 (14) C 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. PMID:25392910

  12. 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.

  13. Comparison of the Geologic Setting of the South Pole-Aitken Basin Interior with Apollo 16: Implications for Regolith Components

    Science.gov (United States)

    Petro, N. E.; Pieters, C. M.

    2004-01-01

    The interior of the South Pole-Aitken Basin (SPA) contains ancient cratered terrain that is possibly remnant of the original interior of the basin. This terrain has been modified by the addition of and mixing with foreign material introduced by later basins and craters of all sizes (lateral and vertical mixing). Since much of our thinking about ancient regolith is based on detailed analysis of samples from one nearside ancient heavily cratered highland site, Apollo 16 (Ap16), it is instructive to compare the interior of SPA with the Ap16 landing site. For this comparison we use a central location within SPA (SPA-1 at 60 deg. S, 160 deg. W). Two models have recently been presented that allow estimation of the amount of original SPA interior material likely to remain in the regolith of SPA. Although the details of each model are different, results consistently range from 50-82% original material in the regolith. The models also allow the contribution from individual basins to be predicted.

  14. Heat flow in Railroad Valley, Nevada and implications for geothermal resources in the south-central Great Basin

    Science.gov (United States)

    Williams, C.F.; Sass, J.H.

    2006-01-01

    The Great Basin is a province of high average heat flow (approximately 90 mW m-2), with higher values characteristic of some areas and relatively low heat flow (heat sink associated with interbasin water flow in the Paleozoic carbonate aquifers. Evaluating this hypothesis and investigating the thermal state of the Eureka Low at depth is a high priority for the US Geological Survey as it prepares a new national geothermal resource assessment. Part of this investigation is focused on Railroad Valley, the site of the largest petroleum reservoirs in Nevada and one of the few locations within the Eureka Low with a known geothermal system. Temperature and thermal conductivity data have been acquired from wells in Railroad Valley in order to determine heat flow in the basin. The results reveal a complex interaction of cooling due to shallow ground-water flow, relatively low (49 to 76 mW m-2) conductive heat flow at depth in most of the basin, and high (up to 234 mW m-2) heat flow associated with the 125??C geothermal system that encompasses the Bacon Flat and Grant Canyon oil fields. The presence of the Railroad Valley geothermal resource within the Eureka Low may be reflect the absence of deep ground-water flow sweeping heat out of the basin. If true, this suggests that other areas in the carbonate aquifer province may contain deep geothermal resources that are masked by ground-water flow.

  15. 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.

  16. Porosity and Permeability of Jurassic-Triassic Formations of the South Georgia Rift Basin: Potential Implications for CO2 Storage

    Science.gov (United States)

    Akintunde, O. M.; Knapp, C. C.; Knapp, J. H.; Prasad, M.; Olsen, P. E.

    2011-12-01

    Porosity and permeability are critical for evaluating reservoir injectivity and seal integrity for subsurface CO2 storage. Both properties are needed to determine the effective CO2 storage capacity. In addition, the ability to model and understand the physical interactions of the CO2 reservoir systems under in situ conditions is dependent on the reservoir porosity. We present results of rock physics evaluation of the porosity and permeability of the buried Jurassic-Triassic formations of the South Georgia Rift (SGR) basin using existing well and new experimental data. The SGR basin covers parts of South Carolina, Georgia, Alabama, and Florida and is buried beneath Cretaceous and younger Coastal Plain sediments. We focused our study on the South Carolina portion of the basin that has been identified in the Carbon Sequestration Atlas of United States and Canada as containing saline formations suitable for subsurface CO2 storage. Results of our rock physics analysis confirm the presence of porous reservoir units capped by low-porosity diabase sills. These potential reservoirs appear to have the capacity (pore volume and porosity) to store significant quantities of supercritical CO2. Our analysis further suggests that the SGR basin may contain distinct porosity-permeability regimes (geo-hydrologic systems) that are influenced by depositional environments. These regimes are: (1) high-porosity, low/medium permeability, as observed in the Norris Lightsey well with Triassic formation porosity of 20 - 32.5 percent and core-derived permeability of 1.5 - 8.9 mD, and (2) low-porosity, low-permeability, based on the average total porosity of 6.3 percent and permeability of 6.6 (E-5) - 1.6 (E-2) mD reported in the literature for the Dunbarton Triassic sediments. The Norris Lightsey sedimentary rocks are primarily lacustrine deposits and consist of fine-grained Triassic sandstone with interbedded layers of siltstone and mudstone, while the Dunbarton basin is dominated by fluvial fine-to very fine-grained sandstone. We believe that our hypothesis of distinct geo-hydrologic systems for the SGR basin requires further evaluation. We will discuss the results of new experiments on selected Jurassic and Triassic core samples that are designed to better understand and quantify the distribution of porosity and permeability both locally and regionally.

  17. Waste-water impacts on groundwater: Cl/Br ratios and implications for arsenic pollution of groundwater in the Bengal Basin and Red River Basin, Vietnam.

    Science.gov (United States)

    McArthur, J M; Sikdar, P K; Hoque, M A; Ghosal, U

    2012-10-15

    Across West Bengal and Bangladesh, concentrations of Cl in much groundwater exceed the natural, upper limit of 10 mg/L. The Cl/Br mass ratios in groundwaters range up to 2500 and scatter along mixing lines between waste-water and dilute groundwater, with many falling near the mean end-member value for waste-water of 1561 at 126 mg/L Cl. Values of Cl/Br exceed the seawater ratio of 288 in uncommon NO(3)-bearing groundwaters, and in those containing measurable amounts of salt-corrected SO(4) (SO(4) corrected for marine salt). The data show that shallow groundwater tapped by tube-wells in the Bengal Basin has been widely contaminated by waste-water derived from pit latrines, septic tanks, and other methods of sanitary disposal, although reducing conditions in the aquifers have removed most evidence of NO(3) additions from these sources, and much evidence of their additions of SO(4). In groundwaters from wells in palaeo-channel settings, end-member modelling shows that >25% of wells yield water that comprises ?10% of waste-water. In palaeo-interfluvial settings, only wells at the margins of the palaeo-interfluvial sequence contain detectable waste water. Settings are identifiable by well-colour survey, owner information, water composition, and drilling. Values of Cl/Br and faecal coliform counts are both inversely related to concentrations of pollutant As in groundwater, suggesting that waste-water contributions to groundwater in the near-field of septic-tanks and pit-latrines (within 30 m) suppress the mechanism of As-pollution and lessen the prevalence and severity of As pollution. In the far-field of such sources, organic matter in waste-water may increase groundwater pollution by As. PMID:22960402

  18. SHRIMP zircon age of the high aeromagnetic anomaly zone in central Tarim Basin and its geological implications

    Directory of Open Access Journals (Sweden)

    Chengze Zhang

    2011-12-01

    Full Text Available In order to get the correct isotopic age, SHRIMP U-Pb zircon date of Precambrian hornblende granite in Well TD2, located in the central aeromagnetic belt in the eastern of the Tarim basin, was carried out. The result showed a dependable age of 1908.2 ± 8.6 Ma, which demonstrated that the granite pluton is the result of the magmatic activity in early Palaeoproterozoic. It is indicated that the central aeromagnetic belt across Tarim basin, divided it into north and south block, is formed before Neoproterozoic by a large scale tectonothermal events based on the seismic and drilling date. The Tarim continent may have different age and type basements formed the united crystalline basement in Precambrian. This result has yielded new intraplate evidence to constrain the relation between the Tarim plate and the Colombia supercontinent.

  19. Using Satellite Gravity to Map and Model Forearc Basins and Thickness of Trench Sediment Worldwide: Implications for Great Earthquakes

    Science.gov (United States)

    Blakely, R. J.; Scholl, D. W.; Wells, R. E.; von Huene, R.; Barckhausen, U.

    2006-12-01

    There is growing evidence that historic great earthquakes (M>8) favor segments of subduction zones that exhibit key geologic factors, such as high sediment influx into the trench (e.g., Ruff, 1989), the presence of young accretionary prisms (von Huene and Scholl, 1991), the presence of trench-slope forearc basins (Wells et al., 2003; Song and Simons, 2003), and the mineralogical structure of the upper plate. The USGS Tsunami Sources Working Group (http://walrus.wr.usgs.gov/tsunami/workshop/index.html) recently described and quantified these factors for all eastern Pacific subduction margins. Although the level of knowledge of subduction zones world-wide is highly uneven, free-air gravity anomalies observed at satellite altitudes provide a consistent measure of some of these geologic factors. Satellite gravity demonstrates, for example, that regions of greatest slip during past megathrust earthquakes around the circum-Pacific spatially correlate with forearc basins and their associated deep-sea terrace gravity lows, with amplitudes typically >20 mGal. Basins may evolve because interseismic subsidence, possibly linked to basal erosion of the forearc by the subducting plate, does not fully recover after earthquakes. By inference, therefore, forearc basin gravity lows should be predictors of the location of large moment release during future great earthquakes. Moreover, great earthquakes have a statistical propensity to occur at trenches with excess sediments, in contrast to trenches dominated by horst-and-graben bathymetry. After removing the effects of bathymetric depth, low densities associated with trench fill are evident in satellite gravity anomalies and thus permit identification of trench segments with high sediment influx. Additional studies using satellite gravity anomalies may lead to new avenues in understanding the geologic processes that accompany great megathrust earthquakes, but we must confirm the ability of satellite gravity data to serve as a suitable proxy for high-quality marine gravity data. A new compilation of shipboard gravity data from west of Central America (Barckhausen et al., 1998; 2003) affords an excellent opportunity to make this determination. A statistical comparison of satellite and shipboard datasets offshore Nicaragua, Costa Rica, and Panama found average agreement to within 1 mGal and absolute agreement to within 5 mGal everywhere, except very near the coast where errors can be significantly larger. The Sandino forearc basin offshore Nicaragua, for example, is well imaged by satellite gravity anomalies. A preliminary model based strictly on satellite gravity anomalies indicates that the Sandino basin is 7 to 9 km deep, assuming an average density of 2520 kg/m3 for basin fill, a depth that is consistent with multichannel seismic-reflection studies. Most important to future studies of megathrust earthquakes, our comparison shows that conclusions regarding forearc basins would be virtually the same whether drawn from satellite or high-quality shipboard gravity data.

  20. Paleomagnetic and paleoenvironmental implications of magnetofossil occurrences in late Miocene marine sediments from the Guadalquivir Basin, SW Spain

    OpenAIRE

    Cruz Larrasoaña, Juan; LIU, QINGSONG; Hu, Pengxiang; Roberts, Andrew P. Roberts; Mata, Pilar; Civis, Jorge; Sierro, Francisco J.; Pérez-Asensio, José N.

    2014-01-01

    Although recent studies have revealed more widespread occurrences of magnetofossils in pre-Quaternary sediments than have been previously reported, their significance for paleomagnetic and paleoenvironmental studies is not fully understood. We present a paleo- and rock-magnetic study of late Miocene marine sediments recovered from the Guadalquivir Basin (SW Spain). Well-defined paleomagnetic directions provide a robust magnetostratigraphic chronology for the two studied sediment cores. Rock m...

  1. Paleomagnetic and paleoenvironmental implications of magnetofossil occurrences in late Miocene marine sediments from the Guadalquivir Basin, SW Spain

    OpenAIRE

    JuanCruzLarrasoaña; QingsongLiu; AndrewPhilipRoberts; FranciscoJavierSierro; JoséNPérez-Asensio

    2014-01-01

    Although recent studies have revealed more widespread occurrences of magnetofossils in pre-Quaternary sediments than has been previously reported, their significance for paleomagetic and paleoenvironmental studies is not fully understood. We present a paleo- and rock-magnetic study of late Miocene marine sediments recovered from the Guadalquivir Basin (SW Spain). Well-defined paleomagnetic directions provide a robust magnetostratigraphic chronology for the two studied sediment cores. Rock mag...

  2. Hypoxia tolerance of introduced Nile perch: implications for survival of indigenous fishes in the Lake Victoria basin

    OpenAIRE

    Chapman, Lauren J; Pamela J. Schofield

    2011-01-01

    The introduction of predatory Nile perch (Lates niloticus) into the Lake Victoria basin coincided with a dramatic decline in fish diversity. However, remnant populations of indigenous fishes persist in lagoons and satellite lakes separated from the main lakes by extensive areas of swamp, while other indigenous species find refuge in ecotonal areas at edges of marginal swamps in the main lakes. Low-oxygen conditions in these wetlands may physiologically stress Nile perch and therefore minimiz...

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

    OpenAIRE

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

    2011-01-01

    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 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 w...

  4. Information from geology: Implications for soil formation and rehabilitation in the post coal mining environment, Bowen Basin, Australia

    International Nuclear Information System (INIS)

    The coal mining industry is likely to disturb as much as 60,000 ha of the Bowen Basin up to the year 2000. While comprising only a small proportion of the approximately 32,000 km2 of the Bowen Basin, this considerable area will eventually need to be rehabilitated by creating appropriate land forms with a stabilizing and self-sustaining cover of vegetation. The job of restoring the disturbed area will fall to the practitioners of rehabilitation science. This paper briefly outlines the actual and potential significance of geological information to rehabilitation practice in the open-cut coal mining industry of the Bowen Basin. It focuses particularly on the problems of soil formation and the consequent limitations to ecosystem development due to the nature of the overburden materials and the environment. Lastly, it describes some of the distinctive features of the mine-soils of the area. Geological information can assist in the identification, classification, description and behaviour of post-mining materials. Potential inputs are not restricted to these and there is scope for wider inputs to management of the mining environment although the interface with biology requires further development. (author). 4 figs., 31 refs

  5. 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

  6. 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

  7. Observations on sediment sources in the Lower Athabasca River basin: implications of natural hydrocarbons inputs from oil sands deposits

    International Nuclear Information System (INIS)

    Government, industry and public concern exists over the environmental consequences of the development of the oil sand deposits in the McMurray Formation in the lower Athabasca River basin, Alberta. The impact of this development is unclear and is undergoing investigation. Investigations to date have focussed on the nature of the effluent produced by the extraction industry and its effect on biotic systems, and on the spatial distribution of hydrocarbon contaminants associated with deposited fluvial sediments. Natural hydrocarbon outcrops may be responsible for observed biomarker responses in areas not exposed to industrial effluent. Given this source of hydrocarbons and doubt concerning its environmental impact, it is difficult to ascertain the impact of oil extraction activities within a fluvial system. A study was conducted to determine the nature and extent of natural hydrocarbon releases within the context of the sediment regime of the lower Athabasca River basin. A description is included of observations from the field and a context is set up for assessing sediment-bound hydrocarbon contaminants in the lower Athabasca River basin. Abstract only included

  8. Geochemical and isotopic characterization of the Bodélé Depression dust source and implications for transatlantic dust transport to the Amazon Basin

    Science.gov (United States)

    Abouchami, Wafa; Näthe, Kerstin; Kumar, Ashwini; Galer, Stephen J. G.; Jochum, Klaus Peter; Williams, Earle; Horbe, Adriana M. C.; Rosa, João W. C.; Balsam, William; Adams, David; Mezger, Klaus; Andreae, Meinrat O.

    2013-10-01

    The Bodélé Depression (Chad) in the central Sahara/Sahel region of Northern Africa is the most important source of mineral dust to the atmosphere globally. The Bodélé Depression is purportedly the largest source of Saharan dust reaching the Amazon Basin by transatlantic transport. Here, we have undertaken a comprehensive study of surface sediments from the Bodélé Depression and dust deposits (Chad, Niger) in order to characterize geochemically and isotopically (Sr, Nd and Pb isotopes) this dust source, and evaluate its importance in present and past African dust records. We similarly analyzed sedimentary deposits from the Amazonian lowlands in order to assess postulated accumulation of African mineral dust in the Amazon Basin, as well as its possible impact in fertilizing the Amazon rainforest. Our results identify distinct sources of different ages and provenance in the Bodélé Depression versus the Amazon Basin, effectively ruling out an origin for the Amazonian deposits, such as the Belterra Clay Layer, by long-term deposition of Bodélé Depression material. Similarly, no evidence for contributions from other potential source areas is provided by existing isotope data (Sr, Nd) on Saharan dusts. Instead, the composition of these Amazonian deposits is entirely consistent with derivation from in-situ weathering and erosion of the Precambrian Amazonian craton, with little, if any, Andean contribution. In the Amazon Basin, the mass accumulation rate of eolian dust is only around one-third of the vertical erosion rate in shield areas, suggesting that Saharan dust is "consumed" by tropical weathering, contributing nutrients and stimulating plant growth, but never accumulates as such in the Amazon Basin. The chemical and isotope compositions found in the Bodélé Depression are varied at the local scale, and have contrasting signatures in the "silica-rich" dry lake-bed sediments and in the "calcium-rich" mixed diatomites and surrounding sand material. This unexpected finding implies that the Bodélé Depression material is not "pre-mixed" at the source to provide a homogeneous source of dust. Rather, different isotope signatures can be emitted depending on subtle vagaries of dust-producing events. Our characterization of the Bodélé Depression components indicate that the Bodélé "calcium-rich" component, identified here, is most likely released via eolian processes of sand grain saltation and abrasion and may be significant in the overall global budget of dusts carried out by the Harmattan low-level jet during the winter.

  9. Minerals and trace elements in silcretes of the Sado basin (Alentejo, southern Portugal) and implications for silcrete formation

    Science.gov (United States)

    Sauer, Daniela; Kullmann, Sarah; Zarei, Mehdi; Stahr, Karl

    2014-05-01

    Soils in the eastern part of the Sado basin (southern Portugal) are often characterized by massive cementations caused by silica. The thickness and massive character of these silcretes led to the hypothesis that accumulation of silica took place not only vertically within a soil profile, but also by enrichment through lateral water and element flow into the Sado basin. The aims of the study reported here were: 1) to characterize the cementing agent with regard to its mineralogy; 2) to test the hypothesis that silification was enhanced through lateral silica transport from the adjacent Alto Alentejo into the Sado basin. Aim 1) was achieved by scratching silica coatings from ped surfaces of the silicified soil horizons and cleaning them manually in the lab under a binocular microscope. After careful smashing with a mortar, density separation by sodium polytungstate solution was applied to remove any remaining mineral grains from the silica samples. The cleaned silica samples were then subjected to XRD and SEM in combination with EDS. Aim 2) was attained by using trace element contents of predominant rock types of the Alto Alentejo and of the silcretes in the Sado basin for identifying lateral pathways of water and silica in the landscape. Ten rock samples from the assumed source area of silica were combusted by fusion melt, and their contents of Ba, Co, Cs, Nb, Pb, Rb, Sr, Y and Zr were analyzed by ICP-MS. The same elements were analyzed in NaOH extracts of the cemented soil horizons in the Sado basin. The X-ray diagrams of the silica coatings show the expected broad hump of amorphous silica. In addition, quartz, kaolinite, and surprisingly high amounts of halloysite are identified, the latter reflecting conditions of intensive weathering and pedogenesis during the formation of the silica coatings. This intensive soil formation and hence silification most likely took place during Pliocene. Greater age is impossible, because the silification took place in Pliocene sediments; later, on the other hand, the climate became cooler, hence intensity of pedogenesis should have decreased. It is assumed that halloysite was preserved over such long period of time, because it was occluded in the silica mass. The micromorphology of the coatings under the SEM includes laminar coverings, banded and alveolar structures. EDS analysis shows that the coatings consist mainly of silicon; in addition they contain aluminum and some also have minor amounts of iron. Trace element contents of the rock samples and silcretes enabled tracing lateral silica flows from the Alto Alentejo into the Sado basin. Some rock samples and silcretes contained considerable amounts of Barium. Even barite crystals were observed in the silica coatings under the SEM. Acknowledgement The authors thank Beate Podtschaske for her valuable help in the laboratory and the German Research Foundation DFG for financial support (project STA 146/45-3).

  10. Implications of Magmatic Events on Hydrocarbon Generation: Occurrences of Gabbroic Rocks in the Orito Field, Putumayo Basin, SW Colombia

    Science.gov (United States)

    Vásquez, M.; Altenberger, U.; Romer, R. L.

    2005-12-01

    Mafic dikes and sills intruded the sedimentary succession in the Orito Oil Field, located in the Putumayo Basin, SW Colombia. One sample from the Orito-4 well yields a Late Miocene to Pliocene age (40K/40Ar on amphibole 6.1 ± 0.7 Ma) for the igneous event in the basin. This coincides with the widely recognized regional Andean orogenic uplift that affected most of sub-Andean Peru, Ecuador, and Colombia. Furthermore, the uplift consequently coincides with a second pulse of hydrocarbon generation and expulsion in the Putumayo Basin. This second pulse was thermally more evolved than the first one (Late Oligocene - Miocene). The high content of CO2 in the gas budget recovered in different wells along the basin may be related to the heat flux of the mafic intrusions. There are four geological events that coincide with this large scale evolution during the late Miocene to early Pliocene (13 - 3 Ma): regional orogenic uplift, persistent igneous intrusions, CO2 formation, and a second pulse of hydrocarbon generation and expulsion. The Late Miocene - Pliocene age of the intrusion is the key to formulate a hypothesis where these four events are joined together. Regional uplift and intrusions: The mafic rocks of the Orito Oil Field show Sr-Nd-Pb isotopic compositions that suggest derivation from a mantle source below the western edge of the South American continent. The geochemical signature of these rocks that form part of the Northern Volcanic Zone (NVZ) reflects subduction-related magmatism. Thus, they record subduction and start of the last pervasive uplift episode that took place during the Late Neogene. Intrusions and second migration phase: The Late Miocene pulse of hydrocarbon generation and migration coincides closely with the estimated age of the intrusions; therefore, a causal link with the geothermal anomaly induced by the mafic igneous rocks is likely. The temperature of a mafic magma reaching 1000 to 1200°C is sufficient to heat the host rocks, where the abundance of dikes eventually changed the regional heat flux. Intrusions and CO2: The presence of CO2 in the basin can be explained as the result of carbonate breakdown associated with igneous intrusions in carbonate sequences. Moreover, since the carbonates are part of the source and reservoir formations of the basin, this gas represents a fundamental factor when assessing the economic risk during various exploration phases. These gabbroic intrusions played an important role in the paleo-heat flow scenario. The magmatic input led to an increase of the maturity of the source rock. The combination of the four elements mentioned above from middle Miocene to Pliocene favored the formation of thermally more-evolved hydrocarbons, but also promoted the generation of major contents of CO2 accumulating in the same traps as the hydrocarbons.

  11. Horizontal degasification and characterization of coals in the Sabinas Sub-basin, Mexico: implications for CBM production

    Energy Technology Data Exchange (ETDEWEB)

    Gentzis, T.; Murray, K.; Klinger, R.; Santillan, M. [CDX Canada Co., Calgary, AB (Canada)

    2006-09-15

    The Sabinas sub-basin in northern Mexico contains gassy coals in the Upper Cretaceous Los Olmos Formation, based on both historical evidence and current desorption testing. The 'Double Seam' coal is present at shallow depth (< 500 m), has high vitrinite content (> 86 vol%), is well-cleated, shows high diffusivity (average tau) value is 56 hours) and has high natural fracture permeability (> 30 mD) in the minesites. The coal averages 2.2 m in thickness but has a high ash content (32 wt%). A tonstein band is present in the middle of the Double Seam, consisting of vitrinite and inertinite embedded in a matrix of fine clays and quartz. Average desorbed gas content of this medium-volatile bituminous coal (Ro{sub max} = 1.30%) is highest in Mine V (Esmeralda Mine at > 9.0 cm{sup 3}/g). Maximum methane adsorption at an equivalent depth of 300 m is 15 cm{sup 3}/g (as-received basisarb). Coal bed methane is mainly methane (98%) with heating value of 38.21 MJ/m{sup 3} (1026 Btu/ft{sup 3}). The coal is under-pressured and reported to be dry, with possibly free gas in the cleat/fracture system and absence of discrete mineralization. In-seam horizontal drilling prior to longwall mining has resulted in the significant reduction of in-situ gas contents and in an increase of mined coal production per shift. The Sabinas sub-basin coals are suitable for a full-scale coal bed methane (CBM) development using in-seam single horizontal and multi-lateral horizontal drilling. Similarities, but also differences, exist between the Sabinas coals in Mexico and the same coals in the Maverick Basin, Texas.

  12. Seismic constraints on a large mafic intrusion with implications for the subsidence mechanism of the Danish Basin

    DEFF Research Database (Denmark)

    Sandrin, Alessandro; Thybo, Hans

    2008-01-01

    Seismic refraction data from the ESTRID-1 profile are used for seismic velocity modeling along the strike of a large mafic intrusion in the Norwegian-Danish Basin, central Denmark. The P wave velocity structure identifies a ~8 km thick sedimentary succession with velocities between 1.8 and 5.7 km/s. The top basement is defined by a step to vp = 6.2 km/s. In the middle to lower crust a high-velocity body (vp > 6.7 km/s), with its top located at about 10-12 km depth, is interpreted as a high-velocity and high-density gabbroic intrusion of Permian age. This high-velocity body explains the large (~50 mGal) positive gravity anomaly known as Silkeborg Gravity High. The intrusion has a minimum volume of 40,000 km3, which implies that the magma influx and the consequent cooling of the lithosphere from high temperature could have had profound effects on the subsidence of the Danish Basin, in particular because the magma probably intruded during only a few events and other similar structures cover much of the basin. Ananomalously high velocity gradient (from 7.0 km/s in the middle crust to 7.7 km/s at 30-32 km depth) in the central part of the intrusion coincides with an interval without Moho reflections, indicative of a gradual transition zone between the crust and the mantle. This feature may show the location of the feeder dykes of the intrusion.

  13. Eocene fluvial drainage patterns and their implications for uranium and hydrocarbon exploration in the Wind River Basin, Wyoming

    International Nuclear Information System (INIS)

    Paleocurrent maps of the fluvial lower Eocene Wind River Formation in the Wind River Basin of central Wyoming define promising uranium- and hydrocarbon-exploration target areas. The Wind River Formation is thought to have the greatest potential for uranium mineralization in areas where it includes arkosic channel sandstones derived from the granitic core of the Granite Mountains, as in the channel-sandstone bodies deposited in Eocene time by a 40-kilometer segment of the eastward-flowing paleo-Wind River that exended westward from near the town of Powder River on the east edge of the basin. Channel-sandstone bodies with a Granite Mountains source occur south of this segment of the paleo-Wind River and north of the Granite Mountains. The southwestern part of this area includes the Gas Hills uranium district, but the channel-sandstone bodies between the Gas Hills district and the 40-kilometer segment of the paleo-Wind River may also be mineralized. This area includes the southeasternmost part of the Wind River Basin southeast of Powder River and contains northeasterly trending channel-sandstone bodies derived from the Granite Mountains. Limited paleocurrent information from the margins of the Wind River Basin suggests that the paleo-Wind River in Paleocene time flowed eastward and had approximately the same location as the eastward-flowing paleo-Wind River of Eocene time. The channel-sandstone bodies of the paleo-Wind Rivers are potential hydrocarbon reservoirs, particu potential hydrocarbon reservoirs, particularly where they are underlain or overlain by the organic-rich shale and siltstone of the Waltman Shale Member of the Fort Union Formation. If leaks of sulfur-containing gas have created a reducing environment in the Eocene paleo-Wind River channel-sandstone bodies, then I speculate that the areas of overlap of the channel-sandstone bodies and natural-gas fields in the underlying rocks may be particularly favorable areas in which to search for uranium deposits

  14. Evidence of syn tectonic tephrites with nepheline in the Sidi Said Maachou Cambrian basin (coastal Meseta, Morocco); geo dynamic implications

    International Nuclear Information System (INIS)

    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.

  15. Impact of Heterogeneity on Flow in Fluvial-Deltaic Reservoirs: Implications for the Giant ACG field, south Caspian Basin

    OpenAIRE

    Choi, Kevin

    2011-01-01

    Abstract The Azeri, Chirag and Gunashli (ACG) oilfield is located in the offshore Azerbaijan sector of the south Caspian Basin~ This dissertation focuses on the Azeri Field which has over 8 billion barrels of oil in place. The major reservoir interval is the Pliocene Pereriv Suite, which is characterized by laterally continuous layers of variable net-to-gross (NTG) deposited in a fluvial-deltaic environment. The Azeri Field is being developed by both down-dip water injection and up-dip gas in...

  16. 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 ate 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

  17. Impacts of Climate Change on Vector Borne Diseases in the Mediterranean BasinImplications for Preparedness and Adaptation Policy

    Science.gov (United States)

    Negev, Maya; Paz, Shlomit; Clermont, Alexandra; Pri-Or, Noemie Groag; Shalom, Uri; Yeger, Tamar; Green, Manfred S.

    2015-01-01

    The Mediterranean region is vulnerable to climatic changes. A warming trend exists in the basin with changes in rainfall patterns. It is expected that vector-borne diseases (VBD) in the region will be influenced by climate change since weather conditions influence their emergence. For some diseases (i.e., West Nile virus) the linkage between emergence andclimate change was recently proved; for others (such as dengue) the risk for local transmission is real. Consequently, adaptation and preparation for changing patterns of VBD distribution is crucial in the Mediterranean basin. We analyzed six representative Mediterranean countries and found that they have started to prepare for this threat, but the preparation levels among them differ, and policy mechanisms are limited and basic. Furthermore, cross-border cooperation is not stable and depends on international frameworks. The Mediterranean countries should improve their adaptation plans, and develop more cross-sectoral, multidisciplinary and participatory approaches. In addition, based on experience from existing local networks in advancing national legislation and trans-border cooperation, we outline recommendations for a regional cooperation framework. We suggest that a stable and neutral framework is required, and that it should address the characteristics and needs of African, Asian and European countries around the Mediterranean in order to ensure participation. Such a regional framework is essential to reduce the risk of VBD transmission, since the vectors of infectious diseases know no political borders. PMID:26084000

  18. 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.

  19. Geochemistry of End-Permian Crater Lake Sediments in the Tunguska Basin, Siberia, and the Implications for Extinction Mechanisms

    Science.gov (United States)

    Fristad, K. E.; Svensen, H.; Planke, S.; Polozov, A. G.

    2008-12-01

    The end of the Permian period is marked by global warming and the largest known mass extinction on Earth. The crisis is commonly attributed to the formation of the Siberian Traps Large Igneous Province although the causal mechanisms remain disputed. One of the proposed mechanisms is the generation of carbon gases and halocarbons in contact aureoles in the Tunguska Basin and subsequent gas venting to the atmosphere. We are testing this hypothesis by performing detailed geochemistry and biostratigraphy on crater lake deposits overlying an end-Permian phreatomagmatic pipe in the southern parts of the Tunguska Basin. During an expedition to the Bratsk region in 2006 we sampled a 1300 meter long core drilled through the center of a crater lake and the underlying brecciated pipe. The core consists of 550 meters of fine to coarse grained clastic lake deposits and 750 meters of sedimentary and volcanic breccias. Preliminary biostratigraphy results show that the sediments contain abundant and exceptionally well preserved end- Permian and early-Triassic palynomorphs, supporting a causal link between the formation of the breccia pipe and the crater lake and the end-Permian extinction. Ongoing isotope stratigraphy aims at documenting the exact timing between the crater lake formation and the initial Triassic carbon isotope excursion.

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

    OpenAIRE

    Quiroga, S.; 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...

  1. Late Paleogene reactivation of the Sinnyeong Fault in the Gyeongsang Basin, SE Korea and its tectonic implications

    Science.gov (United States)

    Cheon, Y.; Song, C. W.; Kim, J. S.; Lee, S. K.; Son, M.

    2014-12-01

    The WNW-trending Gaeum Fault System (GFS) in the Cretaceous Gyeongsang Basin can give important clues for understanding the crustal deformation history in the SE Korea during the late Cretaceous to Paleogene. This study focuses on the Sinnyeong Fault, one of the most conspicuous strands among the GFS, based on the detailed field observations. Its main movement is interpreted as sinistral strike-slip with small reverse component, although it could have experienced other faultings with difference senses before/after this movement. An intriguing feature of the fault is the asymmetry of damage zones on both sides of the fault core. Sedimentary strata of the southern damage zone are much more folded and deformed than those of the northern damage zone, and the southern damage zone width is much wider than the northern one. The NW-trending en-echelon folds are also exclusively localized in the southern periphery along the fault with a continuous width less than 30 m, indicating a NE-SW compressional stress regime. The folds are interpreted to have formed coevally with or immediately before the sinistral movement of the fault, because they only occur in the nearby area of the fault and are sharply cut by the fault core. The asymmetric damage zone probably resulted from the concentration of regional compressional stress along pre-existing WNW-trending weak zone, such as densely populated fracture zone, within a relatively stable intraplate region. In the Gyeongsang Basin, the NNE-trending Yangsan Fault System dextrally cuts through the granites of ca. 48 Ma and the GFS sinistrally cuts through the granites of ca. 52 Ma. These similar ages as well as the geometries and kinematics of the two fault systems support that they acted as a great conjugate fault system under the NE-SW compressional stress regime. In addition, many previous studies have mentioned that the regional crustal uplift, folding, and reactivation of inherited structures occurred due to a tectonic inversion in East Asia during the late Eocene to Oligocene. It is thus concluded that the most conspicuous two fault systems in the Gyeongsang Basin were reactivated simultaneously as a conjugate fault system along the suitably orientated pre-existing crustal weaknesses under the NE-SW compressional stress regime during the late Paleogene.

  2. Potential Implications of PCM Climate Change Scenarios for Sacramento-San Joaquin River Basin Hydrology and Water Resources

    Energy Technology Data Exchange (ETDEWEB)

    Van Rheenen, N.T.; Wood, A.W.; Palmer, R.N.; Lettenmaier, D.P. [Department of Civil and Environmental Engineering, 164 Wilcox Hall, P.O. Box 352700, University of Washington, Seattle, WA 98195-2700 (United States)

    2004-07-01

    The potential effects of climate change on the hydrology and water resources of the Sacramento-San Joaquin River Basin were evaluated using ensemble climate simulations generated by the U.S. Department of Energy and National Center for Atmospheric Research Parallel Climate Model (DOE/NCAR PCM). Five PCM scenarios were employed. The first three were ensemble runs from 1995-2099 with a 'business as usual' global emissions scenario, each with different atmospheric initializations. The fourth was a 'control climate' scenario with greenhouse gas emissions set at 1995 levels and run through 2099. The fifth was a historical climate simulation forced with evolving greenhouse gas concentrations from 1870-2000, from which a 50-year portion is taken for use in bias-correction of the other runs. From these global simulations, transient monthly temperature and precipitation sequences were statistically downscaled to produce continuous daily hydrologic model forcings, which drove a macro-scale hydrology model of the Sacramento-San Joaquin River Basins at a ?-degree spatial resolution, and produced daily streamflow sequences for each climate scenario. Each streamflow scenario was used in a water resources system model that simulated current and predicted future performance of the system. The progressive warming of the PCM scenarios (approximately 1.2C at midcentury, and 2.2C by the 2090s), coupled with reductions in winter and spring precipitation (from 10 to 25%), markedly reduced late spring snowpack (by as much as half on average by the end of the century). Progressive reductions in winter, spring, and summer streamflow were less severe in the northern part of the study domain than in the south, where a seasonality shift was apparent. Results from the water resources system model indicate that achieving and maintaining status quo (control scenario climate) system performance in the future would be nearly impossible, given the altered climate scenario hydrologies. The most comprehensive of the mitigation alternatives examined satisfied only 87-96% of environmental targets in the Sacramento system, and less than 80% in the San Joaquin system. It is evident that demand modification and system infrastructure improvements will be required to account for the volumetric and temporal shifts in flows predicted to occur with future climates in the Sacramento-San Joaquin River basins.

  3. Evidence of clastic evaporites in the canyons of the Levant basin (Israel): implications for the Messinian salinity crisis

    Science.gov (United States)

    Lugli, Stefano; Schreiber, B. Charlotte; Gvirtzman, Zohar; Manzi, Vinicio; Roveri, Marco

    2013-04-01

    The recognition of widespread and thick evaporite deposits below the floor of the Mediterranean Sea has boosted a long standing controversy concerning their depositional setting (shallow versus deep) and their correlation with the onshore sequences. Until a new scientific campaign might be launched to cross those deposits, the discussion is still open to speculation. Many Messinian evaporitic deposits have been interpreted as primary precipitates in very shallow-water or coastal environments, thus favouring the idea of a desiccated Mediterranean basin (Hsu et al., 1973). Recent studies have questioned this interpretation (Hardie and Lowenstein, 2004) and widespread, thick, clastic evaporite facies have been identified in the Mediterranean (Manzi et al., 2005). These clastic deposits are not compatible with a desiccation model as they were clearly emplaced by fully subaqueous, deep-water processes, ranging from submarine slides, to high- and low-density gravity flows. One of the most relevant areas for the understanding of the salinity crisis is the Levant basin where the Messinian evaporites partially fill some of the erosional features (canyons) considered to have formed as a consequence of significant drawdown related to the desiccation of the Mediterranean Sea (up to - 850 m, Druckman et al., 1995). Our complete revisitation of the available cores from onshore Israel cutting through the sedimentary filling of the Messinian canyons (Afiq 1, Ashdod 2, Be'eri Sh1, Be'eri Sh4, Jaffa 1 and Talme-Yaffe 3) revealed exclusively clastic sulfate facies. This is the first direct evidence that the Lower Evaporite Unit offshore Israel may actually consist of deep-water resedimented evaporites that were originally deposited on the margin of the Levant Basin. References Druckman Y., Buchbinder B., Martinotti G.M., Tov R.S., Aharon P., 1995. The buried Afiq Canyon (eastern Mediterranean, Israel): a case study of a Tertiary submarine canyon exposed in Late Messinian times. Marine Geology, 123, 167-185. Hardie L.A. & Lowenstein T.K., 2004. Did the Mediterranean Sea dry out during the Miocene? A reassessment of the evaporite evidence from DSDP Legs 13 and 42A cores. JSR, 74, 453-461. Hsu, K.J., Cita, M.B., and Ryan, W.B.F, 1973. The origin of the Mediterranean evaporites, in Ryan, W.B.F., et al. eds., Initial Reports of the Deep Sea Drilling Project, v. 13, Washington, 1203-1231. Manzi V., Lugli S., Ricci Lucchi F., Roveri M., 2005. Deep-water clastic evaporites deposition in the Messinian Adriatic foredeep (northern Apennines, Italy): did the Mediterranean ever dry out? Sedimentology, 52, 875-902.

  4. Vestiges of an Iapetan rift basin in the New Jersey Highlands: implications for the Neoproterozoic Laurentian margin

    Science.gov (United States)

    Gates, Alexander E.; Volkert, Richard A.

    2004-04-01

    Thin, discontinuous remnants of Neoproterozoic intracratonic rift-basin deposits of the Chestnut Hill Formation occur in the western New Jersey Highlands. These deposits form an important link between well-documented Iapetan rift-basins in both the northern and southern Appalachians. The close spatial relations of Chestnut Hill rocks to Paleozoic sedimentary rocks open the possibility that additional Iapetan rift-basins could be concealed beneath the rocks of the Valley and Ridge Province to the west indicating a much broader zone of rifting than has been previously proposed. The Chestnut Hill Formation is intermittently exposed along a 100 km-long band that extends northeast from Pennsylvania nearly to New York State. The lower part of the Chestnut Hill Formation is composed of interbedded lithic pebble- to boulder-conglomerate and feldspathic sandstone grading upward into interbedded phyllite, feldspathic and quartz sandstone, local paleosaprolite, quartz-pebble conglomerate, thin limestone lenses, volcanic, and volcaniclasic rocks, abundant bedded ironstone (hematite ore), and ultimately into diamictites that are interpreted as possible tilloids and containing rounded intra and extrabasinal clasts of the other lithologies. Extensive soft-sediment deformation, cross bedding, and clastic dikes are common in all but the lowest and upper facies. Banded hematite layers occur preferentially in fine-grained tuffs and tuffaceous sediments, but hematitization has affected most lithologies. Volcanic rocks consist of altered rhyolitic tuffs and lapilli tuffs that are interbedded with sediments. The Chestnut Hill Formation is interpreted to have been deposited in early alluvial, and later a complex of fluvial, lacustrine and deltaic environments. Provenance studies based upon petrographic and geochemical analysis of clastic rocks indicate that the sediments are predominantly immature and reflect derivation from local uplifted felsic basement sources in a rifted-margin tectonic setting. Low to moderate weathering of the source rocks is indicated by the geochemistry of most samples, as is the locally intense effect of hydrothermal alteration. Most occurrences of the Chestnut Hill Formation are associated with major faults that exhibit normal movement of apparent Neoproterozoic age. Rocks from the Morgan Hill fault near Easton, Pennsylvania display consistent normal shear sense and vary from low temperature S-C mylonites to breccia that contains deformed pieces of Chestnut Hill Formation.

  5. Shear Wave Velocity Structure Beneath the Western Basin and Range Province, Eastern California: Implications for Crustal-scale Tectonic Models

    Science.gov (United States)

    Kamath, N.; Leslie, S.; Mooney, W. D.

    2007-12-01

    Broadband seismic data from three seismic stations located within the western Basin and Range Province of eastern California were analyzed in order to image the shear wave velocity structure of the crust and upper mantle in the region. The stations include: (1) Manual Prospect Mines, Trona, (2) Cottonwood Creek, Lone Pine, and (3) Slate Mountain, Trona. The area of the study is characterized by a complex geologic history predominantly involving the Mesozoic emplacement of the Sierra Nevada batholith and Cenozoic extension, uplift, and volcanism. Lateral and vertical velocity variations deduced from receiver-function analyses indicate complex lithospheric structure in this region. The crustal configuration beneath the stations depicts a low-velocity zone (LVZ) that is present between 16-18 km depth and the Moho at about 30-km depth. These results are consistent with extensional models of the region involving lateral flow of mid- to lower-crustal material and/or delamination of the lower crust.

  6. 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)

  7. Petrologic and age relations of the Apollo 16 rocks - Implications for subsurface geology and the age of the Nectaris basin

    Science.gov (United States)

    James, O. B.

    1982-01-01

    In connection with its proximity to the Nectaris basin, the Apollo 16 site is the prime lunar sampling site for dating the Nectaris impact. It is found that the Ar-40/Ar-39 data set upper limits on the time of formation of the major types of breccia at the Apollo 16 site. These are 3.92 b.y. for the feldspathic fragmental breccias, and 3.92 b.y. for the dimict breccias. The data establish that the major subsurface units at the site were deposited no longer than 3.92 b.y. ago. Recent developments indicate that the bulk of the material at the site probably has Nectarian or pre-Nectarian ages. An age of 3.9 b.y. must be a rough upper limit to the age of the Nectaris impact. This limit must be verified by additional studies.

  8. 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.

  9. The Thermo-Tectonic Evolution of Hoodoo Dome, Ellef Ringnes Island: Implications for Petroleum Exploration in the Sverdrup Basin

    Science.gov (United States)

    Springer, A. C.; Guest, B.

    2011-12-01

    Over one hundred evaporite diapirs, cored by Carboniferous Otto Fiord Fm., reside along the Sverdrup Basin's axis in the Canadian High Arctic. However, due to the remoteness of this region their tectonic evolution and hydrocarbon potential remain poorly understood. This study focuses on one of the better known diapirs, Hoodoo Dome, located on Ellef Ringnes Island. We use ground-based geological mapping as well as (U-Th)/He thermochronology to better understand the thermal evolution of the rocks around the dome and tectonic influences on salt migration. Our goal is to improve the understanding of thermal histories and hydrocarbon potential of the salt structures in the Sverdrup Basin. The Sverdrup Basin is a steep sided pericratonic trough estimated to contain approximately thirteen kilometers of Carboniferous to Tertiary strata. At Hoodoo Dome, sandstone samples from the Early Cretaceous Isachsen Fm. and Late Cretaceous Hassle Fm. were collected at Hoodoo Dome for apatite and zircon (U-Th)/He thermochronology, a fairly new low temperature thermochronometric technique that yields cooling ages marking a sample's passage through the ~ 70°C and ~175-193°C isothermal surfaces. Samples were collected along 2 transects (north-south and east-west) across Hoodoo Dome, where seven samples yielded sufficient apatite grains and ten samples yielded sufficient zircon grains. The apatite sample suite exhibits a large distribution of apatite helium (AHe) ages, both reset and non-rest. Only 2 samples, BG 14-35-2 and BG 14-34-4 are interpreted as completely reset. Sample BG 14-35-2, the stratigraphically oldest sample, yielded a mean AHe age of 59.2 ±3.9 Ma, whereas sample BG 14-34-4, approx. 150m up section from BG 14-35-2 yielded a mean AHe age of 69.4 ±4.2 Ma. These reset ages suggest that dome uplifting was active by ?70 Ma at the latest and continued until at least ?60 Ma, consistent with the timing the Eurekan Orogeny. The remaining AHe ages from samples collected farther from the dome core and up-section of BG 14-34-4 by ?500m-1300m exhibit both reset and non-reset AHe ages ranging from ?41.3 Ma-1670 Ma. These data suggest long-term residence in the Partial retention zone (PRZ) where grains have experienced partial He loss at shallow depths (<2km). Zircon helium (ZHe) ages from the two transects, yielded a broad distribution of pre depositional ages of 157.9 Ma-2417.5 Ma. These ages are most likely source rock exhumation ages and are consistent with the shallow burial interpretation of the AHe data. This study complements recent studies conducted using legacy seismic and well log back-stripping across Hoodoo Dome which were used to qualitatively answer questions regarding the rate, mechanism, and regional influence of diapirism during the Dome's development. Our results add new quantitative data regarding the ascent of the evaporite core as well as thermal histories for the rocks surrounding Hoodoo Dome. Finally, we hypothesize that salt cored structures elsewhere in the Sverdrup Basin will exhibit similar thermal history patterns, interpreted here as indicating compression induced salt extrusion in the Latest Cretaceous at the onset of the Eurekan Orogeny.

  10. Paleomagnetic and paleoenvironmental implications of magnetofossil occurrences in late Miocene marine sediments from the Guadalquivir Basin, SW Spain

    Directory of Open Access Journals (Sweden)

    JuanCruzLarrasoaña

    2014-03-01

    Full Text Available Although recent studies have revealed more widespread occurrences of magnetofossils in pre-Quaternary sediments than has been previously reported, their significance for paleomagetic and paleoenvironmental studies is not fully understood. We present a paleo- and rock-magnetic study of late Miocene marine sediments recovered from the Guadalquivir Basin (SW Spain. Well-defined paleomagnetic directions provide a robust magnetostratigraphic chronology for the two studied sediment cores. Rock magnetic results indicate the dominance of intact magnetosome chains throughout the studied sediments. These results provide a link between the highest-quality paleomagnetic directions and higher magnetofossil abundances. We interpret that bacterial magnetite formed in the surface sediment mixed layer and that these magnetic particles gave rise to a paleomagnetic signal in the same way as detrital grains. They, therefore, carry a magnetization that is essentially identical to a post-depositional remanent magnetization and that we term a bio-depositional remanent magnetization (BDRM. Some studied polarity reversals record paleomagnetic directions that appear to be delayed by 60-70 kyr. Magnetofossils in these cases are interpreted to carry a biogeochemical remanent magnetization (BGRM that is locked in at greater depth in the sediment column. A sharp decrease in magnetofossil abundance toward the middle of the studied boreholes broadly coincides with a major rise in sediment accumulation rates near the onset of the Messinian salinity crisis (MSC, an event caused by interruption of the connection between the Mediterranean Sea and the Atlantic Ocean. This correlation appears to have resulted from dilution of magnetofossils by enhanced terrigenous inputs that were driven, in turn, by sedimentary changes triggered in the basin at the onset of the MSC. Our study highlights the importance of magnetofossils as carriers of high-quality paleomagnetic and paleoenvironmental signals.

  11. Paleomagnetic and paleoenvironmental implications of magnetofossil occurrences in late Miocene marine sediments from the Guadalquivir Basin, SW Spain.

    Science.gov (United States)

    Larrasoaña, Juan C; Liu, Qingsong; Hu, Pengxiang; Roberts, Andrew P; Mata, Pilar; Civis, Jorge; Sierro, Francisco J; Pérez-Asensio, José N

    2014-01-01

    Although recent studies have revealed more widespread occurrences of magnetofossils in pre-Quaternary sediments than have been previously reported, their significance for paleomagnetic and paleoenvironmental studies is not fully understood. We present a paleo- and rock-magnetic study of late Miocene marine sediments recovered from the Guadalquivir Basin (SW Spain). Well-defined paleomagnetic directions provide a robust magnetostratigraphic chronology for the two studied sediment cores. Rock magnetic results indicate the dominance of intact magnetosome chains throughout the studied sediments. These results provide a link between the highest-quality paleomagnetic directions and higher magnetofossil abundances. We interpret that bacterial magnetite formed in the surface sediment mixed layer and that these magnetic particles gave rise to a paleomagnetic signal in the same way as detrital grains. They, therefore, carry a magnetization that is essentially identical to a post-depositional remanent magnetization, which we term a bio-depositional remanent magnetization. Some studied polarity reversals record paleomagnetic directions with an apparent 60-70 kyr recording delay. Magnetofossils in these cases are interpreted to carry a biogeochemical remanent magnetization that is locked in at greater depth in the sediment column. A sharp decrease in magnetofossil abundance toward the middle of the studied boreholes coincides broadly with a major rise in sediment accumulation rates near the onset of the Messinian salinity crisis (MSC), an event caused by interruption of the connection between the Mediterranean Sea and the Atlantic Ocean. This correlation appears to have resulted from dilution of magnetofossils by enhanced terrigenous inputs that were driven, in turn, by sedimentary changes triggered in the basin at the onset of the MSC. Our results highlight the importance of magnetofossils as carriers of high-quality paleomagnetic and paleoenvironmental signals even in dominantly terrigenous sediments. PMID:24624124

  12. Distribution of sulfur and pyrite in coal seams from Kutai Basin (East Kalimantan, Indonesia): Implications for paleoenvironmental conditions

    Energy Technology Data Exchange (ETDEWEB)

    Widodo, Sri [Department of Mining Engineering, Moslem University of Indonesia, Jln. Urip Sumoharjo, Makassar (Indonesia); Oschmann, Wolfgang [Institute of Geosciece, J.W. Goethe-University, Altenhoeferallee 1, D-60438 Frankfurt a.M. (Germany); Bechtel, Achim; Sachsenhofer, Reinhard F. [Department of Applied Geoscience and Geophysics, University of Leoben, Peter-Tunner-Str.5, A-8700 Leoben (Austria); Anggayana, Komang [Department of Mining Engineering, Bandung Institute of Technology, Jln. Ganesa 10, I-40132 Bandung (Indonesia); Puettmann, Wilhelm [Institute of Atmospheric and Environmental Sciences, Dapartment of Analytical Enviromental Chemistry, J.W. Goethe-University, Altenhoeferallee 1, D-60438 Frankfurt a.M. (Germany)

    2010-03-01

    Thirteen Miocene coal samples from three active open pit and underground coal mines in the Kutai Basin (East Kalimantan, Indonesia) were collected. According to our microscopical and geochemical investigations, coal samples from Sebulu and Centra Busang coal mines yield high sulfur and pyrite contents as compared to the Embalut coal mine. The latter being characterized by very low sulfur (< 1%) and pyrite contents. The ash, mineral, total sulfur, iron (Fe) and pyrite contents of most of the coal samples from the Sebulu and Centra Busang coal mines are high and positively related in these samples. Low contents of ash, mineral, total sulfur, iron (Fe) and pyrite have been found only in sample TNT-32 from Centra Busang coal mine. Pyrite was the only sulfur form that we could recognize under reflected light microscope (oil immersion). Pyrite occurred in the coal as framboidal, euhedral, massive, anhedral and epigenetic pyrite in cleats/fractures. High concentration of pyrite argues for the availability of iron (Fe) in the coal samples. Most coal samples from the Embalut coal mine show lower sulfur (< 1 wt.%) and pyrite contents as found within Centra Busang and Sebulu coals. One exception is the coal sample KTD-38 from Embalut mine with total sulfur content of 1.41 wt.%. The rich ash, mineral, sulfur and pyrite contents of coals in the Kutai Basin (especially Centra Busang and Sebulu coals) can be related to the volcanic activity (Nyaan volcanic) during Tertiary whereby aeolian material was transported to the mire during or after the peatification process. Moreover, the adjacent early Tertiary deep marine sediment, mafic igneous rocks and melange in the center of Kalimantan Island might have provided mineral to the coal by uplift and erosion. The inorganic matter in the mire might also originate from the ground and surface water from the highland of central Kalimantan. (author)

  13. Sensitivity analysis of a sediment dynamics model applied in a Mediterranean river basin: global change and management implications.

    Science.gov (United States)

    Sánchez-Canales, M; López-Benito, A; Acuña, V; Ziv, G; Hamel, P; Chaplin-Kramer, R; Elorza, F J

    2015-01-01

    Climate change and land-use change are major factors influencing sediment dynamics. Models can be used to better understand sediment production and retention by the landscape, although their interpretation is limited by large uncertainties, including model parameter uncertainties. The uncertainties related to parameter selection may be significant and need to be quantified to improve model interpretation for watershed management. In this study, we performed a sensitivity analysis of the InVEST (Integrated Valuation of Environmental Services and Tradeoffs) sediment retention model in order to determine which model parameters had the greatest influence on model outputs, and therefore require special attention during calibration. The estimation of the sediment loads in this model is based on the Universal Soil Loss Equation (USLE). The sensitivity analysis was performed in the Llobregat basin (NE Iberian Peninsula) for exported and retained sediment, which support two different ecosystem service benefits (avoided reservoir sedimentation and improved water quality). Our analysis identified the model parameters related to the natural environment as the most influential for sediment export and retention. Accordingly, small changes in variables such as the magnitude and frequency of extreme rainfall events could cause major changes in sediment dynamics, demonstrating the sensitivity of these dynamics to climate change in Mediterranean basins. Parameters directly related to human activities and decisions (such as cover management factor, C) were also influential, especially for sediment exported. The importance of these human-related parameters in the sediment export process suggests that mitigation measures have the potential to at least partially ameliorate climate-change driven changes in sediment exportation. PMID:25302447

  14. Seabed morphology and gas venting features in the continental slope region of KrishnaeGodavari basin, Bay of Bengal: Implications in gas–hydrate exploration

    Digital Repository Service at National Institute of Oceanography (India)

    Dewangan, P.; Ramprasad, T.; Ramana, M.V.; Mazumdar, A.; Desa, M.; Badesab, F.K.

    2010-01-01

    Increased oil and gas exploration activity has led to a detailed investigation of the continental shelf and adjacent slope regions of Mahanadi, KrishnaeGodavari (KG) and Cauvery basins, which are promising petroliferous basins along the eastern...

  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. 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...

  17. 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.

  18. Organic geochemistry of the Lower Suban coal seam, South Sumatra Basin, Indonesia: Palaeoecological and thermal metamorphism implications

    Energy Technology Data Exchange (ETDEWEB)

    Amijaya, H.; Schwarzbauer, J.; Littke, R. [University of Aachen, Aachen (Germany)

    2006-07-01

    Hydrocarbons extracted from the Tertiary age coals from the Lower Suban seam, South Sumatra Basin, Indonesia have been investigated using gas chromatography (GC) and combined gas chromatography/mass spectrometry (GC/MS). Low rank (vitrinite-huminite reflectance about to 0.41-0.45%) coals from the Tambang Air Laya mine represent different maceral assemblages of an ideal succession of ombrogenous palaeo-peat development in a vertical section. High rank coals (vitrinite reflectance about to 1.42-5.18%) from the Suban mine have been thermally metamorphosed by an andesitic intrusion. Variations in the distributions of n-alkanes, isoprenoids and saturated and aromatic biomarkers in the low rank coals reflect variations in local source input and palaeomire conditions. Terpenoid biomarkers, such as cadinane- and eudesmane-type sesquiterpenoids and oleanane- and ursane-type triterpenoids, indicate the predominance of angiosperm plants in the palaeomire, particularly Dipterocarpaceae. The distribution of hopanoids is affected by the organic facies of the coal and their maturity, and correlates with the palaeomire evolution as derived from petrological studies. Close to the igneous intrusion, rapid thermal stress has destroyed most of the biomarkers, but variations in n-alkane distributions, attributable to palaeomire conditions, remain. Reversals in the trends for molecular parameters based on aliphatic hydrocarbons (n-alkane distribution and pristane/phytane ratio) and aromatic hydrocarbons (methyl phenanthrenes) with coal rank are observed.

  19. Ichnofabrics of the Capdevila Formation (early Eocene) in the Los Palacios Basin (western Cuba): Paleoenvironmental and paleoecological implications

    Science.gov (United States)

    Villegas-Martín, Jorge; Netto, Renata Guimarães; Lavina, Ernesto Luis Correa; Rojas-Consuegra, Reinaldo

    2014-12-01

    The ichnofabrics present in the early Eocene siliciclastic deposits of the Capdevila Formation exposed in the Pinar del Rio area (Los Palacios Basin, western Cuba) are analyzed in this paper and their paleoecological and paleoenvironmental significance are discussed. Nine ichnofabrics were recognized in the dominantly sandy sedimentary succession: Ophiomorpha, Asterosoma, Thalassinoides, Palaeophycus, Scolicia, Bichordites-Thalassinoides, Rhizocorallium, Scolicia-Thalassinoides and rhizobioturbation. Diversity of ichnofauna is low and burrows made by detritus-feeding organisms in well oxygenated and stenohaline waters predominate. Suites of the Cruziana and Skolithos Ichnofacies lacking their archetypical characteristics were recognized, being impoverished in diversity and presenting dominance of echinoderm and decapods crustacean burrows as a response to the environmental stress caused by the high frequency of deposition. The ichnofabric distribution in the studied succession, its recurrence in the sandstone beds and the presence of a Glossifungites Ichnofacies suite with rhizobioturbation associated reflect a shoaling-upward event with subaerial exposure of the substrate. The integrated analysis of the ichnology and the sedimentary facies suggests deposition in a shallow slope frequently impacted by gravitational flows and high-energy events. The evidence of substrate exposure indicates the occurrence of a forced regression and suggests the existence of a sequence boundary at the top of the Capdevila Formation.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. Late Triassic tuff intervals in the Ordos basin, Central China: Their depositional, petrographic, geochemical characteristics and regional implications

    Science.gov (United States)

    Qiu, Xinwei; Liu, Chiyang; Mao, Guangzhou; Deng, Yu; Wang, Feifei; Wang, Jianqiang

    2014-02-01

    Tuff intervals of Upper Triassic Yanchang Formation are laterally widespread in the Ordos basin, Central China. This paper focuses on magmatic origins and potential source regions of these tuff intervals through detail depositional, petrographic and geochemical analyses. Most of the tuff intervals are well-documented at the bottom of the Chang7 oil reservoir unit and can be correlated laterally, and certain tuff beds are reworked by turbidity current or seismic activity. Petrographic studies of the Chang7 tuffs indicate that they are composed of crystal shards, lithic shards and altered glass shards, and the crystal shards include plagioclase, quartz and biotite. Alteration of the Chang7 tuffs is ubiquitous, thus, most of these tuffs transformed into illite/smectite (I/S) mixed-layers which are identified by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Less common minerals are also detected in the Chang7 tuffs such as zircon, hematite, siderite, anatase. Major elements are determined by the X-ray fluorescence (XRF) analysis, the results indicate that the Chang7 tuffs are enriched in K2O (average 4.21%), the ratio of SiO2/Al2O3 ranges from 1.73 to 2.85 (average 2.17), and the ratio of TiO2/Al2O3 varies between 0.006 and 0.032 (average 0.017), which imply that the Chang7 tuffs originated from a felsic parental magma. Trace elements are determined by inductively coupled plasma mass spectrometry (ICP-MS), indicating the total rare earth element (?REE) concentrations are variable, and range from 117.46 to 466.83 ppm (average 251.88 ppm). REE distribution pattern of the Chang7 tuffs presents a LREE rightward incline with flat HREE curve. The value of ?Eu ranges from 0.151 to 0.837 (average 0.492), suggesting a strong to weak negative Eu anomaly. The Chang7 tuffs show positive anomalies in Rb, Th and U and negative anomalies in Nb, Sr and Eu on a primitive mantle normalized spidergram. A preliminary analysis of the geochemical composition of the Chang7 tuffs suggests a parental magma origin of rhyodacite/dacite, which came from volcanic arc-related setting along an active continental margin. Combined with the chronology and geochemical studies of the synchronous Tianshui rhyolite in the West Qinling Mountains, we propose that the west Qinling Mountains is one of the potential source regions of these tuffs, and the Middle-Late Triassic terminal closure of eastern Tethys provided the arc-related magma.

  5. 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).

  6. 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

  7. Lineaments Extraction from Gravity Data by Automatic Lineament Tracing Method in Sidi Bouzid Basin (Central Tunisia): Structural Framework Inference andHydrogeological Implication

    OpenAIRE

    Hajer Azaiez; Hakim Gabtni; Imen Bouyahya; Dorra Tanfous; Mourad Bedir

    2011-01-01

    The gravity method may be used in the exploration of deep sedimentary basins. It allows the structuring and the lateral and vertical extent of sedimentary fill to be determined. This study has concerned a qualitative and quantitative gravity analysis of Sidi Bouzid Basin in Central Tunisia. Bouguer anomaly analysis and Gravity data filtering allows us to emphasize the structures affecting the basin. The Automatic Lineament Tracing method helps to quantify the different gravity responses of fa...

  8. Land Use/Cover Change in the Middle Reaches of the Heihe River Basin over 2000-2011 and Its Implications for Sustainable Water Resource Management

    OpenAIRE

    Hu, Xiaoli; Lu, Ling; Li, Xin; WANG, JIANHUA; Ming GUO

    2015-01-01

    The Heihe River Basin (HRB) is a typical arid inland river basin in northwestern China. From the 1960s to the 1990s, the downstream flow in the HRB declined as a result of large, artificial changes in the distribution of water and land and a lack of effective water resource management. Consequently, the ecosystems of the lower reaches of the basin substantially deteriorated. To restore these degraded ecosystems, the Ecological Water Diversion Project (EWDP) was initiated by the Chinese govern...

  9. Geology of the Eel River basin and adjacent region: implications for late Cenozoic tectonics of the southern Cascadia subduction zone and Mendocino triple junction

    Science.gov (United States)

    Clarke, S.H., Jr.

    1992-01-01

    Two upper Cenozoic depositional sequences of principally marine strata about 4000m thick overlie accreted basement terranes of the Central and Coastal belts of the Franciscan Complex in the onshore-offshore Eel River basin of northwestern California. The older depositional sequence is early to middle Miocene in age and represents slope basin and slope-blanket deposition, whereas the younger sequence, late Miocene to middle Pleistocene in age, consists largely of forearc basin deposits. -from Author

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

    Science.gov (United States)

    Dill, H. G.; Kharel, B. D.; Singh, V. K.; Piya, B.; Busch, K.; Geyh, M.

    2001-10-01

    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. Alluvial through lacustrine sedimentation during incipient stages is a direct response to uplift in the hinge zone of the synclinorium. Axial parallel sediment dispersal gave way to fluviodeltaic sedimentation mainly from the limbs of the synclinorium. Ongoing compression and renewed uplift in the core zone of the synclinorium drove the uplift of a NW-SE running divide and a subdivision of the mono-lake into two basins. This ridge blocked the flow of transverse rivers and the northern subbasin became gradually choked. Ongoing uplift of the entire basin during the recent geological history caused a reorganization of the drainage pattern and triggered linear erosion in the southern mountain range. Step-by-step the remaining lacustrine basins disappeared. Fan aggradation coincide with cold dry or warm seasons, fluvial dissection and discharge increased during warmer and more humid periods. High lake levels exist during phases of increased humidity. 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.

  11. 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.

  12. High resolution carbon isotope stratigraphy and glendonite occurrences of the Christopher Formation, Sverdrup Basin (Axel Heiberg Island, Canada): implications for mid Cretaceous high latitude climate change

    Science.gov (United States)

    Herrle, Jens O.; Schröder-Adams, Claudia J.; Galloway, Jennifer M.; Pugh, Adam T.

    2013-04-01

    Understanding the evolution of Canada's Arctic region, as a crucial component of Earth's climate system, is fundamental to assess short and long-term climate, environmental, and paleogeographic change. However, the stratigraphy and paleoenvironmental evolution of the Cretaceous Arctic is poorly constrained and a detailed bio- and chemostratigraphic correlation of major mid-Cretaceous paleoceanographic turning points such as Oceanic Anoxic Events, cold snaps, and biotic turnovers with key locations of the high- and low latitudes is missing. Here we present for the first time a high resolution bio- and carbon isotope stratigraphy of the Arctic Albian Christopher Formation of the Sverdrup Basin at Glacier Fiord in the southern part of Axel Heiberg Island, Canadian High Arctic. By using these techniques we developed a high temporal framework to record major environmental changes as it is indicated by the occurrence of glendonites and sandstone intervals of our studied Albian succession. The Albian Christopher Formation is a shale dominated marine unit with a thickness of approximately 1200 m. Several transgressive/ regressive cycles can be recognized by prograding shoreface units that break up mudrock deposition. In addition, glendonites are mainly found in the lower part of the Christopher Formation. Glendonites are pseudomorphs of calcite, after the metastable mineral ikaite, and have been often described from high latitude Permian, Jurassic and Cretaceous marine environments from the Canadian Arctic, Spitsbergen and Australia. The formation of glendonites takes place in the uppermost layer of the sediment and requires near-freezing temperatures, high salinity, and orthophosphate-rich bottom water. Although the presence of glendonites implies a range of paleoenvironmental conditions there is a consensus in the scientific literature that they reflect cooler paleoenvironmental conditions. Preliminary bio- and carbon isotope stratigraphic results suggest that the glendonites are concentrated in regular beds during the late Aptian to early Albian of the Christopher Formation supporting the idea of a cold snap (Kemper, 1987; Herrle & Mutterlose 2003; Mutterlose et al. 2009) within the mid-Cretaceous greenhouse period. References Herrle, J.O., Mutterlose, J., 2003. Calcareous nannofossils from the Aptian - early Albian of SE France: Paleoecological and biostratigraphic implications. Cretaceous Research 24, 1-22. Kemper, E., 1987. Das Klima der Kreide-Zeit. Geologisches Jahrbuch 96, 185 pp. Mutterlose, J., Bornemann, A., Herrle, J.O., 2009. The Aptian - Albian cold snap: Evidence for "mid" Cretaceous icehouse interludes. Neues Jahrbuch für Geologie und Palaeontologie, Abhandlungen 252, 217-225.

  13. Recent Advances in Modeling Phosphorus and Nitrogen Delivery to the Gulf of Mexico and Implications for Managing Nutrients n the Mississippi River Basin

    Science.gov (United States)

    Alexander, R. B.; Smith, R. A.; Schwarz, G. E.; Boyer, E. W.; Nolan, J. V.; Brakebill, J. W.

    2008-12-01

    Although the increased availability of reactive nutrients in past decades has benefited society via food and energy production, the corresponding rise in nutrient loadings to aquatic ecosystems is of particular concern, especially in many estuaries globally where increased nutrient loads have contributed to eutrophic conditions. In the United States, elevated riverine nutrients have contributed to stressed trophic conditions in a majority of estuaries, including the shallow coastal waters of the Louisiana shelf in the northern Gulf of Mexico, where both nitrogen and phosphorus loadings are recognized as contributing to seasonal hypoxic conditions. Advances in geospatial modeling of nitrogen and phosphorus sources and transport in the Mississippi and Atchafalaya River Basins (MARB), as reported in a recent U.S. Geological Survey (USGS) study, provide important information to support improved assessments and management of nutrient loadings to the northern Gulf of Mexico. We summarize the findings of this study and discuss the implications for managing nutrient sources in the MARB. The study reveals important differences in the sources and aquatic transport of nitrogen and phosphorus that affect delivery to the Gulf. Although agricultural sources contribute a majority of the delivered nutrients to the Gulf, corn and soybean cultivation is the largest contributor of nitrogen whereas phosphorus originates primarily from animal manure on pasture and rangelands. Atmospheric deposition is the second leading source of nitrogen, with urban sources contributing relatively small quantities of both nutrients. Furthermore, we find that both nitrogen and phosphorus delivery to the Gulf is controlled by hydrological and biogeochemical processes (e.g., water travel time, denitrification, storage) that scale with stream size, although phosphorus also displays large local- and regional-scale differences in delivery caused by reservoir trapping. The importance of these processes underscores the need to account for the nonlinear interactions of aquatic transport processes with watershed nutrient sources in developing efficient nutrient reduction strategies for the MARB. Such strategies will need to consider a diversity of nutrient sources, including the different effects of agricultural production systems on nitrogen and phosphorus runoff to streams, the contributions of atmospheric nitrogen, and improved management of phosphorus sources downstream from reservoirs.

  14. The Density and Porosity of Lunar Impact Breccias and Impact Melt Rocks and Implications for Gravity Modeling of Impact Basin Structure

    Science.gov (United States)

    Kiefer, W. S.; Macke, R. J.; Britt, D. T.; Irving, A. J.; Consolmagno, G. J.

    2015-02-01

    Measured bulk densities of lunar impact breccias and melt rocks increase the basin melt sheet thickness inferred with GRAIL gravity data. The grain densities of these rocks are consistent with an origin from a mixture of crust and mantle material.

  15. Late Miocene to Plio-Pleistocene fluvio-lacustrine system in the Karacasu Basin (SW Anatolia, Turkey): Depositional, paleogeographic and paleoclimatic implications

    Science.gov (United States)

    Alçiçek, Hülya; Jiménez-Moreno, Gonzalo

    2013-06-01

    The sedimentary record of the late Cenozoic Karacasu Basin, a long-lived continental half-graben from southwestern Turkey, is characterized by siliciclastic and carbonate deposits. Sedimentation was controlled by an active NW-SE trending major normal fault along the basin's southern margin and by climatically-induced lake-level changes. Detailed facies analysis subdivides the entire Neogene-Quaternary basin-fill into three distinct litostratigraphic units representing paleogeographic changes and sedimentation patterns throughout the basin evolution. Sedimentation commenced in the late Miocene with the deposition of proximal-medial alluvial fan and fluvial facies (Damdere Formation; FA1). At this stage, alluvial fans developed in elevated areas to the south, prograding towards the basin center. At the beginning of the Pliocene, fresh to slightly alkaline, shallow lake deposits (FA2a) of the Karacaören Formation formed. The lake became open and meromictic conditions developed (FA2b). Pollen data from the FA2b facies show that climate was arid to humid. Climate probably changed cyclically through time producing alternation of Artemisia steppe (cold and dry periods) and more forested vegetation (warm and wet). The open lake facies passes upwards into lake margin facies (FA2c), but it was still dominated by alkaline to slightly saline lake conditions. Sedimentation was almost continuous from the late Miocene to Pleistocene. In the early Quaternary, the basin was dissected by the re-activation of basin bounding faults. The unconformable base of the overlying Quaternary deposits (Karacasu Formation; FA3) reflected the basin's transformation from a half-graben into a full-graben system. Oxygen isotope data from carbonates show an alternation of humid climatic periods, when freshwater settings predominated, and semiarid/arid periods in which the basin hosted alkaline and saline water lakes. Neotectonic activity has rejuvenated many of the basin-bounding faults, causing development of talus aprons and local alluvial fans. The basin was progressively incised by modern rivers that have largely smoothed out the topographic relief of the graben margins. id="ab0010" The study highlights to the paleo-geography/-climatology in the east Mediterranean.

  16. Oligocene-Miocene spreading history of the northern South Fiji Basin and implications for the evolution of the New Zealand plate boundary

    OpenAIRE

    Herzer, R. H.; Barker, D. H. N.; Roest, Walter; Mortimer, N

    2011-01-01

    A tectonic model of the evolution of the northern half of the South Fiji Basin, including the Minerva Triple Junction and Cook Fracture Zone, is developed from regional gravity, multibeam bathymetry, and a new interpretation of magnetic anomalies pinned to radiometric dates of oceanic crust in the basin. The geometry and age of a portion of the Minerva Triple Junction and the Cook-Minerva spreading center (the connection from the triple junction to the Cook Fracture Zone, which accommodated c...

  17. The Messinian-early Pliocene stratigraphic record in the southern Bajo Segura Basin (Betic Cordillera, Spain): implications for the Mediterranean salinity crisis

    OpenAIRE

    Soria Mingorance, Jesús Miguel; Caracuel Martín, Jesús Esteban; Corbí Sevila, Hugo Antonio; Dinarès Turell, Jaume; Lancis Sáez, Carlos; Tent Manclús, José Enrique; Viseras Alarcón, César; Yébenes Simón, Alfonso

    2008-01-01

    The analysis of the Messinian and Pliocene stratigraphy of the southern Bajo Segura Basin (Betic Cordillera, Spain) has revealed three highstand sedimentary phases (Messinian I, Messinian II, and Pliocene) bounded by two lowstand erosional surfaces (intra-Messinian and end-Messinian unconformities). The Messinian I highstand phase is characterized by the progradation of coastal and shallow marine sandstones (La Virgen Fm) over slope and pelagic-basin marls (Torremendo Fm). After this first ph...

  18. 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 %.

  19. New Constraints on Buried Triassic Basins of the Eastern North American Margin and Implications for Regional Tectonics from Reanalysis of SeisData6 Seismic Profile

    Science.gov (United States)

    Knapp, C. C.; Akintunde, O. M.; Knapp, J. H.

    2012-12-01

    The Eastern North American Margin (ENAM) is most significant due to the complexity and regional extent of this mature Mesozoic passive margin rift system encompassing: (1) a large volume and regional extent of related magmatism, (2) a preserved complete stratigraphic column that records the post-rift evolution in several basins, (3) preserved lithospheric-scale pre-rift structures including Paleozoic sutures, and (4) a wide-range of geological, geochemical, and geophysical studies both onshore and offshore. The short-lived but most voluminous magmatic event associated with the initiation of rifting, the Central Atlantic Magmatic Province (CAMP), is one of the most significant magmatic events in North America. The South Georgia Rift (SGR) basin is believed to be the largest and probably the most geologically complex Mesozoic graben of the ENAM formed during crustal extension associated with the breakup of Pangea and later opening of the North Atlantic Ocean. The separation of the African and North American plates, the formation of the Atlantic Ocean and the associated zones of weakness in eastern North America have been stated as the initial events in the breakup of Pangea. At least four major unanswered questions of regional tectonic significance derive from a previous study of the USGS SeisData6 seismic profile across the Coastal Plain of South East Georgia and are now addressed through reprocessing. These issues are: (1) the stratigraphy, structural composition, extent and thickness of this buried basin which have remained unknown, (2) whether or not the SGR basin is connected with the Riddleville and Dunbarton basins in Georgia and South Carolina, (3) whether or not the Augusta fault, an inferred crustal scale thrust fault which approximately represents the Piedmont-Coastal Plain boundary in Georgia and South Carolina, extends underneath the Coastal Plain sediments, and (4) weather there is evidence of CAMP basalt flows or sills within the SGR basin along this transect. A key significant discovery of this study is the substantiation of the presence of a buried Triassic basin inferred to be the subsurface convergence of the Riddleville and Dunbarton basins. Both basins appear to be subsidiaries of the main SGR basin. The SGR basin is about 2.2 km deep, 170 km wide and it appears to be bounded in the south-east by normal faults resembling graben-like structures. Basin-bounding faults reactivated as reverse faults during Cretaceous and Cenozoic times are common in many of the buried Mesozoic rift basins of the Southern Appalachians. The basin fill is mostly sedimentary rocks and no basalt was encountered. Absence of basalt in this area implies that erosion, uplift and possibly fault reactivation may have limited the regional extent of voluminous basaltic flows extruded during ENAM's magmatism. Seismically, we found no evidence to suggest that the Augusta fault extends underneath the Coastal Plain sediments in the study area. Based on correlation of seismic and well data, we interpret the lack of reflections in the NW-end of the profile to be due to the presence of non-reflective metamorphic rocks of the Piedmont Province.

  20. Oligocene-Miocene spreading history of the northern South Fiji Basin and implications for the evolution of the New Zealand plate boundary

    Science.gov (United States)

    Herzer, R. H.; Barker, D. H. N.; Roest, W. R.; Mortimer, N.

    2011-02-01

    A tectonic model of the evolution of the northern half of the South Fiji Basin, including the Minerva Triple Junction and Cook Fracture Zone, is developed from regional gravity, multibeam bathymetry, and a new interpretation of magnetic anomalies pinned to radiometric dates of oceanic crust in the basin. The geometry and age of a portion of the Minerva Triple Junction and the Cook-Minerva spreading center (the connection from the triple junction to the Cook Fracture Zone, which accommodated coeval opening of the Norfolk Basin), are resolved with multibeam bathymetry and magnetics. The South Fiji Basin opened from about 34 to 15 Ma in an anticlockwise sweep about an Euler pole located at the northern end of the present Lau Ridge. This rotation and a rigidly straight southeastward motion of the Three Kings Ridge were accommodated by the configuration of the triple junction changing from ridge-fault-fault to ridge-ridge-fault to ridge-ridge-ridge. During this evolution the southeastern arm of the system, the Julia Fracture Zone, underwent several transformations and the Cook-Minerva spreading center experienced repeated ridge jumps. The kinematics of the northern South Fiji Basin dictate, to a large extent, the evolution of the southern South Fiji Basin and the Norfolk Basin. This in turn leads to the interpretation of a complex trench-trench-double transform fault framework at the northern New Zealand margin, which explains most aspects of the geology, structure, and arc volcanic history of the margin and provides a radical new setting for the origin of the Northland Allochthon.

  1. Formation of South Pole-Aitken Basin as the Result of an Oblique Impact: Implications for Melt Volume and Source of Exposed Materials

    Science.gov (United States)

    Petro, N. E.

    2012-01-01

    The South Pole-Aitken Basin (SPA) is the largest, deepest, and oldest identified basin on the Moon and contains surfaces that are unique due to their age, composition, and depth of origin in the lunar crust [1-3] (Figure 1). SPA has been a target of interest as an area for robotic sample return in order to determine the age of the basin and the composition and origin of its interior [3-6]. As part of the investigation into the origin of SPA materials there have been several efforts to estimate the likely provenance of regolith material in central SPA [5, 6]. These model estimates suggest that, despite the formation of basins and craters following SPA, the regolith within SPA is dominated by locally derived material. An assumption inherent in these models has been that the locally derived material is primarily SPA impact-melt as opposed to local basement material (e.g. unmelted lower crust). However, the definitive identification of SPA derived impact melt on the basin floor, either by remote sensing [2, 7] or via photogeology [8] is extremely difficult due to the number of subsequent impacts and volcanic activity [3, 4]. In order to identify where SPA produced impact melt may be located, it is important to constrain both how much melt would have been produced in a basin forming impact and the likely source of such melted material. Models of crater and basin formation [9, 10] present clear rationale for estimating the possible volumes and sources of impact melt produced during SPA formation. However, if SPA formed as the result of an oblique impact [11, 12], the volume and depth of origin of melted material could be distinct from similar material in a vertical impact [13].

  2. 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.

  3. 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.

  4. The Sculptured Hills of the Taurus Highlands: Implications for the relative age of Serenitatis, basin chronologies and the cratering history of the Moon

    Science.gov (United States)

    Spudis, P.D.; Wilhelms, D.E.; Robinson, M.S.

    2011-01-01

    New images from the Lunar Reconnaissance Orbiter Camera show the distribution and geological relations of the Sculptured Hills, a geological unit widespread in the highlands between the Serenitatis and Crisium basins. The Sculptured Hills shows knobby, undulating, radially textured, and plains-like morphologies and in many places is indistinguishable from the similarly knobby Alpes Formation, a facies of ejecta from the Imbrium basin. The new LROC image data show that the Sculptured Hills in the Taurus highlands is Imbrium ejecta and not directly related to the formation of the Serenitatis basin. This occurrence and the geological relations of this unit suggests that the Apollo 17 impact melts may not be not samples of the Serenitatis basin-forming impact, leaving their provenance undetermined and origin unexplained. If the Apollo 17 melt rocks are Serenitatis impact melt, up to half of the basin and large crater population of the Moon was created within a 30 Ma interval around 3.8 Ga in a global impact "cataclysm." Either interpretation significantly changes our view of the impact process and history of the Earth-Moon system. Copyright 2011 by the American Geophysical Union.

  5. Coupled heat and fluid flow modeling of the Carboniferous Kuna Basin, Alaska: Implications for the genesis of the Red Dog Pb-Zn-Ag-Ba ore district

    Science.gov (United States)

    Garven, G.; Raffensperger, J.P.; Dumoulin, J.A.; Bradley, D.A.; Young, L.E.; Kelley, K.D.; Leach, D.L.

    2003-01-01

    The Red Dog deposit is a giant 175 Mton (16% Zn, 5% Pb), shale-hosted Pb-Zn-Ag-Ba ore district situated in the Carboniferous Kuna Basin, Western Brooks Range, Alaska. These SEDEX-type ores are thought to have formed in calcareous turbidites and black mudstone at elevated sub-seafloor temperatures (120-150??C) within a hydrogeologic framework of submarine convection that was structurally organized by large normal faults. The theory for modeling brine migration and heat transport in the Kuna Basin is discussed with application to evaluating flow patterns and heat transport in faulted rift basins and the effects of buoyancy-driven free convection on reactive flow and ore genesis. Finite element simulations show that hydrothermal fluid was discharged into the Red Dog subbasin during a period of basin-wide crustal heat flow of 150-160 mW/m2. Basinal brines circulated to depths as great as 1-3 km along multiple normal faults flowed laterally through thick clastic aquifers acquiring metals and heat, and then rapidly ascended a single discharge fault zone at rates ??? 5 m/year to mix with seafloor sulfur and precipitate massive sulfide ores. ?? 2003 Elsevier Science B.V. All rights reserved.

  6. Coseismic Slip Beneath Forearc Basins in Great Subduction Zone Earthquakes: Implications for the Size and Mode of Rupture on the Cascadia Subduction Zone

    Science.gov (United States)

    Wells, R. E.; Blakely, R.; Sugiyama, Y.; Scholl, D.

    2002-12-01

    We have examined the relationship between coseismic slip and forearc structure for 29 of the largest circum-Pacific megathrust earthquakes. Coseismic slip distributions were compiled from published seismic, geodetic, and tsunami waveform inversions, and we interpreted forearc structure from satellite gravity and bathymetry and marine geology. Seismogenic slip is generally focused beneath forearc deep sea terraces and basins, which are underlain by relatively high velocity arc or continental crust. Along the non-accretionary margins of NE Japan, Kuriles, and Kamchatka, the high slip areas roughly correlate with the width of the deep sea terrace, and the landward edge of the terrace approximately coincides with the landward limit of interplate thrust focal mechanisms. Along accretionary margins, coseismic slip is commonly focused beneath the offshore forearc basins. In the 1923, 1944, 1946, and 1968 earthquakes along the Nankai and Sagamai Trough of SW Japan, slip was focused beneath five forearc basins, and the presently locked Tokai source region is centered on a sixth. The steep gravity gradient marking the landward edge of the basins coincides with the landward decrease in coseismic slip and the 350°C isotherm on the plate boundary, approximately marking the down-dip limit to stick-slip behavior. Similar coseismic slip beneath basins is also observed along the Aleutian, Mexico, Peru, and S. Chile subduction zones. Transverse forearc gravity highs which separate the basins commonly overlie areas of lower coseismic slip, as at Cape Erimo separating the 1952 and 1968 Tokachi-oki earthquakes off Hokkaido, the Shumagin gap separating the 1938 and 1946 earthquakes in S. Alaska, and the Portlock anticline separating the Kodiak and Prince William Sound asperities in 1964. If the long-term slip budget is balanced along the margin, then the intervening gravity highs may be future sources of great slip not observed historically, or more likely are regions of smaller interseismic strain accumulation, as is observed in the Shumagin gap. The empirical relationship between high coseismic slip and forearc basins suggests that forearc basins may be useful indicators of long-term seismic moment release in some subduction zones. The inferred source zone of the 1700 AD Mw~9 Cascadia earthquake contains five very large basin-centered gravity lows, the largest of which is 350 km long off the mouth of the Columbia River. These lows, corresponding to the Eel, Coos Bay, Newport-Willapa, and Olympic basins, lie within the locked and transition zones inferred from geodetic data and may indicate at depth. The steep gravity gradient marking the inboard edge of the basins and presumably the downdip limit to large coseismic slip lies beneath Grays Harbor and the western Olympic Peninsula in Washington and just offshore Oregon, between the 350°C and 450° C isotherms on the megathrust. Transverse gravity highs between the basins suggest the margin is seismically segmented and may produce a variety of large earthquakes.

  7. Sandstone distribution at the 14At1 level in the E-G area, south central Bredasdorp Basin: implications for a predictive depositional model

    International Nuclear Information System (INIS)

    In the E-G sub-basin of the south central Bredasdorp Basin, an Albian age unconformity, termed the 14At1 surface, displays an erosional topography of submarine channels. Gamma ray log motifs, together with seismic, and petrographic evidence in the form of sidewall cores and drill cuttings, suggest that these sandstones were deposited in a submarine fan environment. It is proposed that these fans represent the first phase of sedimentation on the 14At1 surface, during sea-level lowstand conditions. 2 figs., 2 refs

  8. 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 elementsseem 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.

  9. 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: 2.752, year: 2013

  10. From source to sink in the sediment cascade of the Hei-River Basin: Implications for late Quaternary landscape dynamics in the Gobi Desert, NW China

    Science.gov (United States)

    Schimpf, Stefan; Nottebaum, Veit; Diekmann, Bernhard; Hartmann, Kai; Lehmkuhl, Frank; Wünnemann, Bernd; Zhang, Chi

    2014-05-01

    The Hei River Basin with a catchment size of ~130,000 km² is host to one of the largest continental alluvial fans in the world. The basin comprises: (1) its high-elevated river sources in the glacier and the permafrost zone of the Qilian Mountains, (2) the semi-arid foreland of the Hexi Corridor in the middle reaches and (3) the endorheic Ejina Basin (Gaxun Nur Basin) as its recent sink. The river basin is characterized by small subcatchments of hyper-arid mountain ranges of the Gobi-Tienshan and Beishan as well as of smooth and fuzzy water divides of the Hexi-Corridor and the Badain Jaran Sand Sea. Up to 300 m of Quaternary sediments establish the large Ejina Basin, with a size of 28,000 km², as an excellent archive for environmental reconstructions located at the recent intersection of westerly and monsoonal air masses. Three sediment cores (up to 230 m long) provide evidence of sedimentation dynamics over the last 250,000 years, and cover at least two terminations since OIS 6. The sediments have to be regarded as a result of the interplay between tectonic activity and climate dynamics, accompanied by a related eolian and hydrological response of the catchment. Thus, it is crucial to understand and reconstruct the sedimentary processes along the huge sediment cascades, and to identify the most important sediment sources. Here we present a provenance analysis from mineralogical fingerprints of modern sediments that have been deposited along recent pathways from the sources to the Ejina Basin. The methodical approach combines the analysis of clay minerals, bulk mineralogy, and bulk geochemistry. Furthermore, we use heavy mineral data obtained from automated particle-analysis via a computer-controlled scanning electron microscope (CCSEM) and XRD measurements. We analyzed ~200 surface samples from the whole catchment as reference material, as well as the upper 19 m of cored sediments, to gain insight into temporal changes of depositional processes and provenance. Geostatistical analyses of the compositional data reveal a clear discrimination between sediments from the Qilian Shan in the south and from local basin sediments in the north. Moreover the mineralogical fingerprints allow the differentiation of sources from intrusive rocks that are dominant in the Bei Shan mountain sub-catchment, and from greenschist-bearing metamorphic rocks, that are widespread in the Qilian Mountain catchment. Finally, we draw conclusions about the main transport processes and pathways from assumed source regions to the sink (Ejina Basin). The provenance analysis of the sediment core reveals strong changes from local (Bei Shan) to long-distant (Qilian Shan) sources. The Late Pleistocene record reveals frequently changing sediment supply between periodic high mountain runoff and local episodic runoff. We assume that these variations are related to basin internal processes (e.g. fan dynamics, tectonics) and changing environmental conditions that are linked with variations in meltwater runoff and precipitation in the upper reaches of the southern catchment. These conclusions are supported by grain size characteristics that indicate phases of predominant alluvial activity and limnic deposition around the Late Glacial to Holocene transition and enhanced pre-Holocene eolian activity.

  11. A high-resolution stable isotopic record from the Junggar Basin (NW China): Implications for the paleotopographic evolution of the Tianshan Mountains

    Science.gov (United States)

    Charreau, Julien; Kent-Corson, Malinda Louise; Barrier, Laurie; Augier, Romain; Ritts, Bradley D.; Chen, Yan; France-Lannord, Christian; Guilmette, Caroline

    2012-08-01

    This study presents high-resolution oxygen and carbon isotopic records of paleosol carbonates from fluvial sediments and lacustrine carbonates, sampled from the Jingou He and Kuitun He stratigraphic sections, located in the northern Tianshan piedmont. These sections expose remarkable outcrops of Junggar foreland basin sediments that have been previously dated by high-resolution magnetostratigraphy to between ?23.6 and ?1 Ma, and ?10.5 and ?3.1 Ma. A total of 216 samples of fluvio-lacustrine sediments were collected from which isotopic analyses yield ?18O (SMOW) values that range from 13.7‰ to 29.9‰ in the Jingou He section, and 16.3‰ to 21.0‰ in the Kuitun He section. ?13C (PDB) values range from -12.9‰ to 3.0‰ in the Jingou He section and from -7.8‰ to -4.0% in the Kuitun He section. ?18O values decrease between ?25 and 23 Ma, and then remain relatively steady, with the exception of one period that contains samples with higher oxygen isotope values at ?16 Ma. During the periods when there are samples that overlap in time from the Kuitun He and Jingou He sections, we observe a difference of ?1.7% between values from the two locales. The ?13C values also decrease between ?25 and 23 Ma, and then remain relatively steady until ?10 Ma with, again, one short period of higher values at ?16 Ma. Then, between ?10 and 3.1 Ma, carbon isotope values progressively increase. We interpret that ?18O and ?13C isotopic values during lacustrine periods (?25-23 Ma and ?16 Ma) as largely controlled by evaporation and opening/closing of the lake to external inputs. We interpret the ?18O values of paleosol carbonate in the Junggar Basin to be influenced by the hypsometry of the high Tianshan range while the ?13C values may record the uplift history of the depositional area in the foreland basin itself as well as the isotopic composition of plants. Consequently, we conclude that the Jingou He and Kuitun He drainage basins in the Central Tianshan have remained at relatively unchanged elevations for the past ?20 Ma. We also suggest that the elevation of the southern part of the foreland basin increased between ?10 and ?3.1 Ma, probably as a result of tectonic deformation in the piedmont and sedimentary filling of the sedimentary basin. The carbon isotope record remains relatively stable through time, and isotopic values suggest that there was little or no expansion of C4 plants in this region in the late Miocene.

  12. 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 pannel 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

  13. 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.

  14. U.S. Geological Survey 2013 assessment of undiscovered resources in the Bakken and Three Forks Formations of the U.S. Williston Basin Province

    Science.gov (United States)

    Gaswirth, Stephanie; Marra, Kristen R.

    2014-01-01

    The Upper Devonian Three Forks and Upper Devonian to Lower Mississippian Bakken Formations comprise a major United States continuous oil resource. Current exploitation of oil is from horizontal drilling and hydraulic fracturing of the Middle Member of the Bakken and upper Three Forks, with ongoing exploration of the lower Three Forks, and the Upper, Lower, and Pronghorn Members of the Bakken Formation. In 2008, the U.S. Geological Survey (USGS) estimated a mean of 3.65 billion bbl of undiscovered, technically recoverable oil resource within the Bakken Formation. The USGS recently reassessed the Bakken Formation, which included an assessment of the underlying Three Forks Formation. The Pronghorn Member of the Bakken Formation, where present, was included as part of the Three Forks assessment due to probable fluid communication between reservoirs. For the Bakken Formation, five continuous and one conventional assessment units (AUs) were defined. These AUs are modified from the 2008 AU boundaries to incorporate expanded geologic and production information. The Three Forks Formation was defined with one continuous and one conventional AU. Within the continuous AUs, optimal regions of hydrocarbon recovery, or “sweet spots,” were delineated and estimated ultimate recoveries were calculated for each continuous AU. Resulting undiscovered, technically recoverable resource estimates were 3.65 billion bbl for the five Bakken continuous oil AUs and 3.73 billion bbl for the Three Forks Continuous Oil AU, generating a total mean resource estimate of 7.38 billion bbl. The two conventional AUs are hypothetical and represent a negligible component of the total estimated resource (8 million barrels of oil).

  15. A high-resolution stable isotopic record from the Junggar Basin (NW China): Implications for the paleotopographic evolution of the Tianshan Mountains

    OpenAIRE

    Charreau, Julien; Kent-Corson, Malinda Louise; Barrrier, Laurie; Augier, Romain; Ritts, Bradley D.; Yan CHEN; France-Lannord, Christian; Guilmette, Caroline

    2012-01-01

    This study presents high-resolution oxygen and carbon isotopic records of paleosol carbonates from fluvial sediments and lacustrine carbonates, sampled from the Jingou He and Kuitun He stratigraphic sections, located in the northern Tianshan piedmont. These sections expose remarkable outcrops of Junggar foreland basin sediments that have been previously dated by high-resolution magnetostratigraphy to between ?23.6 and ?1 Ma, and ?10.5 and ?3.1 Ma. A total of 216 samples of fluvio-lacu...

  16. 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.

  17. Summer Watering Patterns of Mule Deer in the Great Basin Desert, USA: Implications of Differential Use by Individuals and the Sexes for Management of Water Resources

    OpenAIRE

    Shields, Andrew V.; Larsen, Randy T.; Whiting, Jericho C.

    2012-01-01

    Changes in the abundance and distribution of free water can negatively influence wildlife in arid regions. Free water is considered a limiting factor for mule deer (Odocoileus hemionus) in the Great Basin Desert. Consequently, a better understanding of differential use of water by individuals and the sexes could influence the conservation and management of mule deer and water resources in their habitats. We deployed remote cameras at all known water sources (13 wildlife water developments and...

  18. Paleomagnetism of the Carboniferous-Permian Patquia Formation, Paganzo basin, Argentina: implications for the apparent polar wander path for South America and Gondwana during the Late Palaeozoic

    OpenAIRE

    Geuna, S.E.

    2010-01-01

    The magnetic properties of the Carboniferous-Permian red beds of the Patquía Formation at Punta del Viento, Sierra de Umango and some previously reported localities, all in the Paganzo Basin (Argentina), have been studied. Whereas all sites are characterized by hematite as the main magnetic carrier and a reversed-polarity magnetic remanence, we found a pattern of variation in magnetic properties along the integrated column for Patquía Formation. The Lower Member (Late Carboniferous) showed ...

  19. Unusual concentration of Early Albian arthropod-bearing amber in the Basque-Cantabrian Basin (El Soplao, Cantabria, Northern Spain) : palaeoenvironmental and palaeobiological implications

    OpenAIRE

    Najarro, M.

    2009-01-01

    The El Soplao site is a recently-discovered Early Albian locality of the Basque-Cantabrian Basin (northern Spain) that has yielded a number of amber pieces with abundant bioinclusions. The amber-bearing deposit occurs in a non-marine to transitional marine siliciclastic unit (Las Peñosas Formation) that is interleaved within a regressive-transgressive, carbonate-dominated Lower Aptian-Upper Albian marine sequence. The Las Peñosas Formation corresponds to the regressive stage of this sequenc...

  20. Unusual concentration of Early Albian arthropod-bearing amber in the Basque-Cantabrian Basin (El Soplao, Cantabria, Spain): Palaeoenvironmental and paleobiological implications.

    OpenAIRE

    Najarro, M.; Pen?alver, E.; Rosales, I.; Pe?rez La Fuente, Ricardo; Daviero-gomez, V.; Gomez, B.; Delclo?s Marti?nez, Xavier

    2009-01-01

    The El Soplao site is a recently-discovered Early Albian locality of the Basque-Cantabrian Basin (northern Spain) that has yielded a number of amber pieces with abundant bioinclusions. The amber-bearing deposit occurs in a non-marine to transitional marine siliciclastic unit (Las Peñosas Formation) that is interleaved within a regressive-transgressive, carbonate-dominated Lower Aptian-Upper Albian marine sequence. The Las Peñosas Formation corresponds to the regressive stage of this sequenc...

  1. Micro-tectonic constraints on the evolution of the Barles half-window (Digne Nappe, southern Alps). Implications for the timing of folding in the Valensole foreland basin

    OpenAIRE

    Fournier, Marc; Agard, Philippe; Petit, Carole

    2008-01-01

    The "Vélodrome" overturned syncline, at the northern margin of the Cenozoic foreland basin of Valensole in SE France, was formed during the Late Cenozoic at the front of the Digne nappe. Microstructural analyses reveal that mesoscale faulting in the molassic series, from the Oligocene "Molasse Rouge" at the base to the middle to late Miocene "Valensole Conglomerates" at the top, partly occurred before the folding, as layer-parallel shortening: the NNE-SSW-directed compression is recorded by ...

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

    OpenAIRE

    Tripathi, S. K. M.

    2009-01-01

    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...

  3. Rapid climate change from north Andean Lake Fúquene pollen records driven by obliquity: implications for a basin-wide biostratigraphic zonation for the last 284 ka

    OpenAIRE

    Bogota?-a, R. G.; Groot, M. H. M.; Hooghiemstra, H.; Lourens, L. J.; Linden, M.; Berrio, J. C.

    2011-01-01

    This paper compares a new super-high resolution pollen record from a central location in Lake Fúquene (4 N) with 3 pollen records from marginal sites from the same lake basin, located at 2540 m elevation in the Eastern Cordillera of Colombia. We harmonized the pollen sum of all records, and provided previously published records of climate change with an improved age model using a new approach for long continental pollen records. We dissociated from subjective curve matching and a...

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

    OpenAIRE

    Bouyahiaoui, B; Sage, F; Abtout, A; Klingelhoefer, F; Yelles-chaouche, K; Schnurle, P; Marok, A; Deverchere, J; Arab, M; Galve, A; Collot, J.y

    2015-01-01

    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 ar...

  5. 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, ystems, such as the Murray-Darling Basin, extended trace element maps of sediment offer substantially more applications than radiogenic isotope data alone.

  6. Source tracing of detrital serpentinite in the Oligocene molasse deposits from the western Alps (Barrême basin): implications for relief formation in the internal zone.

    OpenAIRE

    Schwartz, Stéphane; Stéphane, Guillot; Pierre, Tricart; Mathias, Bernet; Sébastien, Jourdan; Thierry, Dumont; Gilles, Montagnac

    2012-01-01

    We present the first contribution of tracing the source area of ophiolitic detritus in the Alpine molasses by Raman spectroscopy. The lower Oligocene molasse deposits preserved in the Barrême basin, in the SW foreland of the western Alpine arc, are known for the sudden arrival of the first "exotic" detritus coming from the internal Alpine zones. Among them, the pebbles of serpentinized peridotites have so far not been studied. We show that they only consist of antigorite serpentinite, implyi...

  7. Structural styles and depositional architecture in the Triassic of the Ninian and Alwyn North fields: Implications for basin development and prospectivity in the Northern North Sea

    Energy Technology Data Exchange (ETDEWEB)

    Tomasso, Mark [School of Geosciences, Grant Institute of Earth Science, The University of Edinburgh, The King' s Buildings, West Mains Road, Edinburgh EH9 3JW, Scotland (United Kingdom); Enhanced Oil Recovery Institute, University of Wyoming, 1000 E. University Avenue, Dept. 4068, Laramie, WY 82071 (United States); Underhill, John R. [School of Geosciences, Grant Institute of Earth Science, The University of Edinburgh, The King' s Buildings, West Mains Road, Edinburgh EH9 3JW, Scotland (United Kingdom); Hodgkinson, Richard A. [School of Geosciences, Grant Institute of Earth Science, The University of Edinburgh, The King' s Buildings, West Mains Road, Edinburgh EH9 3JW, Scotland (United Kingdom); Bowleven PLC, 1 North St. Andrew Lane, Edinburgh EH2 1HX, Scotland (United Kingdom); Young, Mike J. [School of Geosciences, Grant Institute of Earth Science, The University of Edinburgh, The King' s Buildings, West Mains Road, Edinburgh EH9 3JW, Scotland (United Kingdom); StatoilHydro, NO-4035 Stavanger (Norway)

    2008-08-15

    Interpretation of well-calibrated three-dimensional seismic volumes, sedimentological analysis and electrical well-log correlations from the Ninian and Alwyn North fields challenge the long-held view that Mid-Late Jurassic extensional faults in the East Shetland Basin represent a simple reactivation of older (Triassic) fault systems. Restoration for the effects of the younger, predominantly eastward-dipping, Mid-Late Jurassic structures clearly demonstrates that Triassic precursors had a steep, westerly dip. In contrast to the eastern flank of the Viking Graben (e.g. Troll and Oseberg areas), where the west-dipping Triassic structures are reutilised in the Mid-Late Jurassic, those of the East Shetland Basin have largely been dissected and rotated during the later event. Those west-dipping faults that did see later movement appear to have simply acted as minor antithetic structures to the throughgoing east-dipping ones. The Triassic normal fault patterns actively controlled sediment thicknesses and facies distribution within the Lunde and Teist Formations in the basin. Use of seismic stratigraphic surfaces, calibrated by biostratigraphy and chemostratigraphic markers, provides strong evidence that the Triassic depocentres are spatially offset from their Mid-Late Jurassic counterparts. The combination of structural, stratigraphic and sedimentary effects reveal the existence of an emergent deeper Triassic play opportunity in footwall locations to the Mid-Late Jurassic normal faults, which has the potential to extend the life of what is otherwise mature acreage. (author)

  8. 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.

  9. The Detrital White Mica 40Ar/39Ar Record of the Katawaz Remnant Ocean Basin, Pakistan, and Tectonic Implications for the Himalayan Source Region

    Science.gov (United States)

    Zhuang, G.; Najman, Y.; Wijbrans, J. R.; Millar, I.; Carter, A.

    2014-12-01

    The Paleogene-Neogene sedimentary rocks in the Katawaz remnant ocean basin, Pakistan were thought to be a product of a fan-deltaic system, analogous to the modern Indus River and delta. A preliminary detrital zircon U-Pb study (Carter et al 2010) supported materials derived from the nascent western Himalaya and associated magmatic arc but that study was based on too few samples to fully characterize the whole series. Moreover, the chronology in the Katawaz basin was previously not well constrained, which impedes accurate comparison to other Himalaya foreland records. Here, we present a densely sampled study of detrital white mica 40Ar/39Ar. This study aims to: (1) constrain sedimentary ages of major lithostratigraphic units, (2) understand the exhumation history of the source region, and (3) reconstruct the paleodrainage system in NW Himalayan foreland. New 40Ar/39Ar data, together with a complementary study of detrital zircon U-Pb, constrain the sand-rich, fluvial-dominated Shaigalu Member to span from <34-36 Ma (basal sample) to <22 Ma (uppermost sample). The basal Shaigalu Member demonstrates similarity of ages of detrital zircon U-Pb and detrital white mica 40Ar/39Ar; both are characterized by a dominant peak of ca. 37 Ma. The dominant 37 Ma peak of detrital white mica 40Ar/39Ar ages has also been identified in the late Eocene Balakot Formation (Najman et al. 2001), the oldest terrestrial unit in the Himalayan peripheral foreland basin, and which is Himalayan-derived. We interpret the similarity in youngest age peak (37 Ma) between U-Pb and 40Ar/39Ar as a signal of rapid exhumation related to a rising western Himalaya. Our new 40Ar/39Ar data also reveal that sediment sources changed through time, as demonstrated by the disappearance of the 37 Ma population up-section and re-occurrence at the top. This could be related to either migration of the drainage system and/or changes in sediment sources. Finally, our study indicates that the latest Eocene rapid exhumation in the western Himalaya was coeval with its eastern counterpart, as observed in sedimentary records in Bengal Basin, Bangladesh (Najman et al 2008). Both reveal that detritus that reached the remnant ocean basins in west and east were archives of early orogenesis of the Himalaya.

  10. Data-driven modeling of radionuclide inventory at the Savannah River Site F-area seepage basins and implications for long-term behavior predictions

    Science.gov (United States)

    Wiedmer, A.; Hunt, J. R.; Agarwal, D.; Faybishenko, B.

    2012-12-01

    The availability of data is a major constraint in the development of a conceptual model and predictions of physical and chemical processes impacting contaminant behavior in the subsurface. For example, a wealth of data has been collected over the past 60 years from a network of several hundred groundwater wells and surface water monitoring stations at the Department of Energy (DOE) Savannah River Site (SRS). The data were collected during and following the release of low-level liquid waste into seepage basins, as well as during the application of various groundwater remediation techniques. The result is a dataset of over 350,000 measurements. To analyze these data, we used a new data management system being developed as part of the DOE initiative on Advanced Simulation Capability for Environmental Management (ASCEM). This system was developed for easier access, management, visualization, and exploration of large amounts of heterogeneous data. Using this system, we developed a data-driven model for the evaluation of a mass balance and the inventory of the F-Area seepage basins and the groundwater plume. Process operations at the F-area led to the discharge of more than 4×109 L of low-level liquid radioactive waste containing tritium, uranium and fission products into the seepage basins. Between 1953 and 1989, 8.6×104 Ci (corrected for evaporation and decay to 1989) of tritium was released into the basins according to operational data. Starting in the 1960s, SRS monitored radioactivity in the Fourmile Branch (FMB) located downgradient of the basins. Through 1989 around 43% of the total release was detected in FMB, leaving an estimated inventory of 57% in the subsurface as of 1989. This model was used to assess t he sources of uncertainty in the mass balance calculations. The results of calculations of the tritium inventory in groundwater were compared with those from monitoring data prior to remediation, as well as were used to estimate the time needed to achieve the tritium MCL level under natural attenuation conditions.

  11. Fluid inclusions and biomarkers in the Upper Mississippi Valley zinc-lead district; implications for the fluid-flow and thermal history of the Illinois Basin

    Science.gov (United States)

    Rowan, E. Lanier; Goldhaber, Martin B.

    1996-01-01

    The Upper Mississippi Valley zinc-lead district is hosted by Ordovician carbonate rocks at the northern margin of the Illinois Basin. Fluid inclusion temperature measurements on Early Permian sphalerite ore from the district are predominantly between 90?C and I50?C. These temperatures are greater than can be explained by their reconstructed burial depth, which was a maximum of approximately 1 km at the time of mineralization. In contrast to the temperatures of mineral formation derived from fluid inclusions, biomarker maturities in the Upper Mississippi Valley district give an estimate of total thermal exposure integrated over time. Temperatures from fluid inclusions trapped during ore genesis with biomarker maturities were combined to construct an estimate of the district's overall thermal history and, by inference, the late Paleozoic thermal and hydrologic history of the Illinois Basin. Circulation of groundwater through regional aquifers, given sufficient flow rates, can redistribute heat from deep in a sedimentary basin to its shallower margins. Evidence for regional-scale circulation of fluids is provided by paleomagnetic studies, regionally correlated zoned dolomite, fluid inclusions, and thermal maturity of organic matter. Evidence for igneous acti vity contemporaneous with mineralization in the vicinity of the Upper Mississippi Valley district is absent. Regional fluid and heat circulation is the most likely explanation for the elevated fluid inclusion temperatures (relative to maximum estimated burial depth) in the Upper Mississippi Valley district. One plausible driving mechanism and flow path for the ore-forming fluids is groundwater recharge in the late Paleozoic Appalachian-Ouachita mountain belt and northward flow through the Reelfoot rift and the proto- Illinois Basin to the Upper Mississippi Valley district. Warm fluid flowing laterally through Cambrian and Ordovician aquifers would then move vertically upward through the fractures that control sphalerite mineralization in the Upper Mississippi Valley district. Biomarker reactant-product measurements on rock extracts from the Upper Mississippi Valley district define a relatively low level ofthermal maturity for the district, 0.353 for sterane and 0.577 for hopane. Recently published kinetic constants permit a time-temperature relationship to be determined from these biomarker maturities. Numerical calculations were made to simulate fluid heat flow through the fracture-controlled ore zones of the Thompson-Temperly mine and heat transfer to the adjacent rocks where biomarker samples were collected. Calculations that combine the fluid inclusion temperatures and the biomarker constraints on thermal maturity indicate that the time interval during which mineralizing fluids circulated through the Upper Mississippi Valley district is on the order of 200,000 years. Fluid inclusion measurements and thermal maturities from biomarkers in the district reflect the duration of peak temperatures resulting from regional fluid circulation. On the basis of thermal considerations, the timing of fluorite mineralization in southern Illinois, and the northward-decreasing pattern of fluorine enrichment in sediments, we hypothesize that the principal flow direction was northward through the Cambrian and Ordovician aquifers of the Illinois Basin. A basin-scale flow system would result in mass transport (hydrocarbon migration, transport of metals in solution) and energy (heat) transport, which would in turn drive chemical reactions (for example, maturation of organic matter, mineralization, diagenetic reactions) within the Illinois Basin and at its margins.

  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. Petrographic and geochemical characteristics of the Paleogene sedimentary rocks from the North Jiangsu Basin, Eastern China: implications for provenance and tectonic setting

    Science.gov (United States)

    Zhang, Ni; Lin, Chun-Ming; Zhang, Xia

    2014-08-01

    The petrography and geochemistry (major, trace, and rare earth elements) of clastic sedimentary rocks from the Paleogene Dainan Formation (E2 d) in the North Jiangsu Basin, eastern China, are investigated to trace their provenance and to constrain their tectonic setting. The studied samples are characterized by LREE enrichment, flat HREE, and negative Eu anomaly similar to the upper continental crust composed chiefly of felsic components in the source area. Petrographic observation indicates that the sandstones contain predominant metamorphic and sedimentary clasts that were derived from peripheral recycled orogen and intrabasinal materials. The trace element ratios (Co/Th, La/Sc, La/Th, and Th/U) and the La-Th-Sc ternary plot further confirm that the sandstones are derived from granitic gneiss sources from recycled orogen and the intrabasinal mixed sedimentary provenance. The granitic gneiss source rocks may have derived from the Proterozoic granitic gneiss denuded in the eastern Dabie-Sulu orogen; and the intrabasinal provenance may come from the underlying strata during the Late Paleocene Wubao movement. The chemical index of alteration (CIA) and A-CN-K plot show that these source rocks may have experienced weak to medium chemical weathering. Analysis on tectonic setting of the source area suggests an active continental margin, which is intimate with tectonic feature of the Dabie-sulu orogen and the Yangtze block. In summary, we suggest that the North Jiangsu Basin is an ideal site for the study of the coupling between the uplift of the orogen and the subsidence of the foreland basin.

  14. Identification and numerical modelling of hydrocarbon leakage in the Lower Congo Basin: Implications on the genesis of km-wide seafloor mounded structures

    Science.gov (United States)

    Anka, Zahie; Ondrak, Robert; Kowitz, Astrid; Schødt, Niels

    2013-09-01

    We present a combined approach of interpretation of 2D seismic-reflection data and numerical modelling of hydrocarbon generation and migration across the southern slope of the Lower Congo Basin, in order to investigate the factors controlling timing and distribution of hydrocarbon leakage in this area. We identified three main families of past and present-day leakage features: (1) Mid-Upper Miocene seismic chimneys concentrated basinwards and ending up on buried pockmarks, (2) Plio-Pleistocene chimneys, rather clustered to the east of the study area and ending up in seafloor pockmarks, and (3) fewer scattered chimneys identified within the Miocene sequences ending up in shallow enhanced reflectors ("Flat spots"). Stratigraphic and structural elements seem to control the distribution of these features. At least two major events of leakage occurred during the Middle-Late Miocene and intermittently during the Pliocene-Present. External factors as sediment supply are associated to the Miocene leakage event, whilst internal structural elements probably triggered the Pliocene to present-day leakage. A major seabed morphological feature, represented by a margin-paralleled belt of more than 1-km-wide mounds, was identified above growth faults to the east of the study area. Data-constrained 2D HC generation and migration modelling suggests a genetic link between these structures and vertical migration/leakage of thermogenic methane sourced from either currently mature Oligo-Miocene source rocks or secondary cracking and further expulsion from over-mature Upper-Cretaceous source rocks. Hence, the mounds are likely to represent a lineation of methane-derived carbonate build-ups. Despite the natural limitations of a 2D migration model, when combined and calibrated with observations from seismic data, it can be used as a valid tool to assess petroleum migration routes in sedimentary basins. To the best of our knowledge, this is the first integrated approach combining both seismic observations and numerical modelling carried out in the Angola basin.

  15. A Conceptual Model of Water Quantity Impacts from Insect-Induced Tree Mortality in Coniferous Forests: Implications for Colorado River Basin Water Management

    Science.gov (United States)

    Gordon, E.; Pugh, E. T.

    2010-12-01

    In regions with snowpack-dominated hydrology, such as the upper Colorado River Basin, forested watersheds are the source of most (>70%) of the annual runoff. Widespread tree mortality significantly alters many ecohydrologic processes including transpiration, canopy transmission and interception, subcanopy wind regimes, soil infiltration, and snow surface albedo. Since 1996, an outbreak of the mountain pine beetle (MPB; Dendroctonous ponderosae) has killed most mature trees across 14,600 km2 of forests dominated by lodgepole pine (Pinus contorta) in Colorado, with the highest levels of mortality occurring around the headwaters of the Colorado River. Water managers are concerned about potential changes in water yield and timing of runoff resulting from the MPB infestation, but few empirical studies have documented the effects of such infestations on hydrologic processes. We synthesize these studies and other research on forest ecology, hydrology, and timber harvesting to create a conceptual model of the hydrologic effects of MPB-induced tree death during different stages of mortality. We separate out the primary hydrologic processes for living forest stands, stands in multiple stages of mortality, and long-dead stands undergoing regeneration. Our model outlines the direction of change in individual hydrologic processes, but continuing uncertainty over relative magnitude makes it difficult to understand the overall net effect of widespread tree mortality on runoff volume. Overall, the complexity of basin-specific factors that modulate hydrologic processes and differences between phases of stand mortality should caution water managers in the Colorado River Basin against assuming there will be significant changes in yield or timing due to MPB-induced tree mortality.

  16. Petrography and geochemistry of Cretaceous to quaternary siliciclastic rocks in the Tarfaya basin, SW Morocco: implications for tectonic setting, weathering, and provenance

    Science.gov (United States)

    Ali, Sajid; Stattegger, Karl; Garbe-Schönberg, Dieter; Kuhnt, Wolfgang; Kluth, Oliver; Jabour, Haddou

    2014-01-01

    The petrography, heavy mineral analysis, major element geochemical compositions and mineral chemistry of Early Cretaceous to Miocene-Pliocene rocks, and recent sediments of the Tarfaya basin, SW Morocco, have been studied to reveal their depositional tectonic setting, weathering history, and provenance. Bulk sediment compositional and mineral chemical data suggest that these rocks were derived from heterogeneous sources in the Reguibat Shield (West African Craton) including the Mauritanides and the western Anti-Atlas, which likely form the basement in this area. The Early Cretaceous sandstones are subarkosic in composition, while the Miocene-Pliocene sandstones and the recent sediments from Wadis are generally carbonate-rich feldspathic or lithic arenites, which is also reflected in their major element geochemical compositions. The studied samples are characterized by moderate SiO2 contents and variable abundances of Al2O3, K2O, Na2O, and ferromagnesian elements. Binary tectonic discrimination diagrams demonstrate that most samples can be characterized as passive continental marginal deposits. Al2O3/Na2O ratios indicate more intense chemical weathering during the Early Cretaceous and a variable intensity of weathering during the Late Cretaceous, Early Eocene, Oligocene-Early Miocene, Miocene-Pliocene and recent times. Moreover, weathered marls of the Late Cretaceous and Miocene-Pliocene horizons also exhibit relatively low but variable intensity of chemical weathering. Our results indicate that siliciclastics of the Early Cretaceous were primarily derived from the Reguibat Shield and the Mauritanides, in the SW of the basin, whereas those of the Miocene-Pliocene had varying sources that probably included western Anti-Atlas (NE part of the basin) in addition to the Reguibat Shield and the Mauritanides.

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

    Science.gov (United States)

    Tewari, Ram Chandra; Khan, Zahid A.

    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 ? Clarain ? Durain ? Fusain ? Vitrain, and for the Kargali bottom coal seam is: Clarain ? Vitrain ? Fusain ? Durain ? 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.

  18. 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.

  19. Cyclostratigraphy of an orbitally-driven Tithonian-Valanginian carbonate ramp succession, Southern Mendoza, Argentina: Implications for the Jurassic-Cretaceous boundary in the Neuquén Basin

    Science.gov (United States)

    Kietzmann, Diego A.; Palma, Ricardo M.; Iglesia Llanos, Maria Paula

    2015-01-01

    Detailed sedimentological, sequence stratigraphical and cyclostratigraphical analyses have been made from four lower Tithonian-lower Valanginian sections of the Vaca Muerta Formation, exposed in the southern Mendoza area of the Neuquén Basin, Argentina. The Vaca Muerta Formation is characterized by decimetre-scale rhythmic alternations of marls, shales and limestones, and consists of five facies associations, which reflect different paleoenvironmental conditions: basin to restricted outer ramp, outer ramp, and middle ramp. Vertical organization within the Vaca Muerta Formation shows a well-ordered hierarchy of cycles, where elementary cycles, bundles and superbundles with frequencies within the Milankovitch band have been recognized. According to biostratigraphic data, elementary cycles have a periodicity of ~ 20 ky, which correlates with the precession cycle of Earth's axis. Spectral analysis based on series of cycle thickness allows us to identify frequencies of about 400 ky and 90-120 ky, which we interpret as the modulation of the precessional cycle by the Earth's orbital eccentricity. Cycles are probably driven by variations in carbonate exportation, as fluctuations in shallow-water carbonate production involve modifications in carbonate basinward exportation. Cyclostratigraphic data allowed us to build a floating orbital scale for the Tithonian-lower Valanginian interval in the Neuquén Basin. Correlation between studied sections allowed us to recognize a discontinuity between the Substeueroceras koeneni and Argentiniceras noduliferum ammonite zones in the Malargüe Anticline area. Orbital calibration of these sections is consistent with Riccardi's biostratigraphic scheme, wich place the Jurassic-Cretaceous boundary within the Substeueroceras koeneni ammonite Zone. On the other hand, the base of the Vaca Muerta Formation (Virgatosphinctes mendozanus ammonite Zone) would be probably placed in the base of the middle Tithonian rather than the lower Tithonian, which is also consistent with our preliminary palaeomagnetic data.

  20. Ar-40 to Ar-39 dating of pseudotachylites from the Witwatersrand basin, South Africa, with implications for the formation of the Vredefort Dome

    Science.gov (United States)

    Trieloff, M.; Kunz, J.; Jessberger, E. K.; Reimold, W. U.; Boer, R. H.; Jackson, M. C.

    1992-01-01

    The formation of the Vredefort Dome, a structure in excess of 100 km in diameter and located in the approximate center of the Witwatersrand basin, is still the subject of lively geological controversy. It is widely accepted that its formation seems to have taken place in a single sudden event, herein referred to as the Vredefort event, accompanied by the release of gigantic amounts of energy. It is debated, however, whether this central event was an internal one, i.e., a cryptoexplosion triggered by volcanic or tectonic processes, or the impact of an extraterrestrial body. The results of this debate are presented.

  1. Groundwater dynamics under water-saving irrigation and implications for sustainable water management in an oasis: Tarim River basin of western China

    Science.gov (United States)

    Zhang, Z.; Hu, H.; Tian, F.; Yao, X.; Sivapalan, M.

    2014-10-01

    Water is essential for life. Specifically in the oases of inland arid basins, water is a critically limited resource, essential for the development of the socio-economy and the sustainability of eco-environmental systems. Due to the unique hydrological regime present in arid oases, a moderate groundwater table is the goal of sustainable water management. A shallow water table induces serious secondary salinization and collapse of agriculture, while a deep water table causes deterioration of natural vegetation. From the hydrological perspective, the exchange flux between the unsaturated vadose zone and groundwater reservoir is a critical link to understanding regional water table dynamics. This flux is substantially influenced by anthropogenic activities. In the Tarim River basin of western China, where agriculture consumes over 90% of available water resources, the exchange flux between the unsaturated vadose zone and groundwater reservoir is influenced strongly by irrigation. Recently, mulched drip irrigation, a sophisticated water-saving irrigation method, was widely applied in the Tarim River basin, which greatly impacted the exchange flux and thus the regional groundwater dynamics. Capitalizing on recent progress in evaporation measurement techniques, we can now close the water balance and directly quantify the exchange flux at the field scale, thus gaining a better understanding of regional groundwater dynamics. In this study, comprehensive observations of water balance components in an irrigated cropland were implemented in 2012 and 2013 in a typical oasis within the Tarim River basin. The water balance analysis showed that the exchange flux and groundwater dynamics were significantly altered by the application of water-saving irrigation. The exchange flux at the groundwater table is mostly downward (310.5 mm year-1), especially during drip irrigation period and spring flush period, while the upward flux is trivial (16.1 mm year-1) due to the moderate groundwater table depth (annual average depth 2.9 m). Traditional secondary salinization caused by intense phreatic evaporation (fed by upward exchange flux) is alleviated. However, a new form of secondary salinization may be introduced unwittingly if there is lack of water for periodic flushing, especially when brackish water is used in the irrigation. Furthermore, the water saved via drip irrigation has been used in further growth of irrigated lands instead of supporting the ecological system. This could lead to an increased risk of eco-environmental degradation and calls for improved governance schemes. The insights gained from this study can be potentially applied to other arid inland areas (e.g., central Asia) which face similar water shortages and human development problems.

  2. Groundwater Dynamics under Water Saving Irrigation and Implications for Sustainable Water Management in an Oasis: Tarim River Basin of Western China

    Science.gov (United States)

    Zhang, Z.; Hu, H.; Tian, F.; Yao, X.; Sivapalan, M.

    2014-02-01

    Water is essential for life. Specifically in the oases of inland arid basins, water is a critically limited resource, essential for the development of socio-economy and sustainability of eco-environmental systems. Due to the unique hydrological regime present in arid oases, a moderate groundwater table is the goal of sustainable water management. A shallow water table induces serious secondary salinization and collapse of agriculture, while a deep water table causes deterioration of natural vegetation. From the hydrological perspective, the exchange flux between unsaturated vadose zone and groundwater reservoir is a critical link to understand regional water table dynamics. This flux is substantially influenced by anthropogenic activities. In Tarim River Basin of western China, where agriculture consumes over 90% of available water resources, the exchange flux is influenced strongly by irrigation. Recently, mulched drip irrigation, a very advanced water-saving irrigation method, has been widely applied in the Tarim River Basin, which greatly impacted the exchange flux and thus the regional groundwater dynamics. Capitalizing on recent progress in evaporation measurement techniques, we can now close the water balance and directly quantify the exchange flux at the field scale, thus gain a better understanding of regional groundwater dynamics. In this study, comprehensive observations of water balance components in an irrigated cropland were implemented in 2011 and 2012 in a typical oasis within Tarim River Basin. The water balance analysis showed that the exchange flux and groundwater dynamics were significantly altered by the application of water-saving irrigation. The exchange flux is mostly downward (310.5 mm yr-1), especially during drip irrigation period and spring flush period, while the upward flux is trivial (-16.1 mm yr-1) due to the moderate groundwater table depth (annual average depth 2.9 m). Traditional secondary salinization caused by intense phreatic evaporation (fed by upward exchange flux) is alleviated. However, a new form of secondary salinization may be introduced unwittingly if there is lack of water for periodic flushing, especially when brackish water is used in the irrigation. Furthermore, the water saved via drip irrigation has been used in further growth of irrigated lands instead of supporting ecological system. This would lead to increasing risk of eco-environmental degradation and calls for improved governance schemes. The insights gained from this study can be potentially applied to other arid inland areas (e.g., central Asia, sub-Saharan Africa) which face similar water shortages and human development problems.

  3. Deep Seismic Reflection Images across a Major Reactivated Fracture Zone in the Wharton Basin: Implications for the Location of the Plate Boundary between India and Australia

    Science.gov (United States)

    Carton, H. D.; Singh, S. C.; Hananto, N. D.; Martin, J.; Djajadihardja, Y. S.; Udrekh, U.; Franke, D.; Gaedicke, C.

    2012-12-01

    The equatorial Indian Ocean has long been recognized to be hosting extensive "intra-plate" deformation. To west of the Ninety-East Ridge (NER), The Central Indian Ocean Basin is characterized by N-S compression in a broad region with E-W trending folds and high-angle reverse faulting. To the east of NER in the Wharton Basin, deformation mainly occurs along reactivated N5°E-trending oceanic fracture zones with left-lateral strike-slip motion. Near longitude 93°E in the Wharton Basin runs a major reactivated fracture zone, along which the epicenters of the two recent Mw=8.6 and Mw=8.2 strike-slip earthquakes of April 11, 2012, and an Mw=7.2 foreshock that occurred in January 2012 are aligned. The April 11 events are the largest known oceanic events occurring away from the main plate boundaries. They ruptured a 20-40 km thick section of the oceanic lithosphere, i.e. down to depths at which no direct images of fault zones have been obtained so far. Deep seismic reflection data acquired in the Mw=8.6 earthquake rupture zone ~100 km north of the epicenter shows the presence of sub-Moho reflectivity down to 37 km depth in the oceanic mantle. We interpret these events as reflections off the earthquake-generating fault plane in the oceanic mantle, in accordance with results suggesting that brittle deformation of the oceanic lithosphere extends well into the mantle down to the 600°C isotherm. The fracture zone near 93°E separates lithospheres of contrasting crustal thicknesses (3.5-4.5 km versus 6 km) with a 10 Ma age difference, and therefore seems to act as a rheological boundary. We find that the deep reflections could originate from either a plane trending approximately N105°E, at high angle to the fracture zone, or from the fracture zone itself if the dip of the fault surface decreases from nearly vertical in the sediments to about 45° in the oceanic mantle. We propose that this fracture zone is a major tectonic boundary in the Wharton Basin, and that the three 2012 earthquakes ruptured a large section of it as part of a poorly-defined diffuse plate boundary between the Indian and Australian plates, with slip occurring on this re-activated N-S fracture zone and on fossil E-W spreading-related faults. Over 1000 km of this plate boundary could have ruptured since the great 2004 Sumatra earthquake.

  4. Estudio de secuencias secas en la Cuenca del Plata: Implicancias con las sequias / Dry spells in the La Plata basin: Monitoring and trend stability. Drought implication

    Scientific Electronic Library Online (English)

    Gustavo, Naumann; Walter M, Vargas; Juan L, Minetti.

    2008-12-01

    Full Text Available El trabajo estudia las secuencias secas en el ámbito de la Cuenca del Plata. Los datos utilizados son diarios y pertenecen a 98 estaciones que incluyen periodos variables desde 1900 hasta 2005. El propósito fundamental es caracterizar las secuencias secas y en especial sus casos extremos o sequías m [...] eteorológicas en términos diarios. Como marco general se presentan los campos de tendencias de diferentes propiedades de las secuencias secas. A partir de esta información se detectan y comparan cambios temporales en los estados secos. Las tendencias estimadas por dos métodos distintos evidencian un decrecimiento especialmente en el este de la Cuenca en el período común 1972-1998. Finalmente, se analiza la ocurrencia de la sequía de 1988 en escala hemisférica. Esta sequía es una de las más intensas y de mayor extensión que ha ocurrido en gran parte de la cuenca del Río de la Plata. El impacto que este evento produjo en la economía argentina fue mayor a $4 billones de dólares de perdida. Abstract in english This paper studies the dry spells observed in the La Plata Basin, using daily data supplied by 98 stations during variable periods between 1900-2005. The main purpose of this study was to define dry spells, especially their extreme cases (meteorologi cal droughts), and to consider them on a daily ba [...] sis. Trends in over different properties of precipitation and dry spells are presented as a general framework to detect and compare temporal changes in dry states. These trends, estimated by two different methods, show a decrease, especially in the east of the basin during the period 1972-1998. The study of the coherence of extreme dry spell shows that these phenomena occur in subregions reducing the risk of occurrence of one of these events in the entire basin. Also the extreme dry spell occurrence show a seasonal preference suggesting that there is a slight and complex dependence on the annual cycle of precipitation. Finally, the occurrence of the 1988 drought was analyzed in a hemispheric scope. The 1988 drought is considered to be the longest dry spell in the basin. Droughts are studied in detail because water deficits translate to Argentinean economic losses of more than $4 billion dollars.

  5. 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).

  6. Origin of minerals in joint and cleat systems of the Pottsville Formation, Black Warrior basin, Alabama: Implications for coalbed methane generation and production

    Science.gov (United States)

    Pitman, J.K.; Pashin, J.C.; Hatch, J.R.; Goldhaber, M.B.

    2003-01-01

    Coalbed methane is produced from naturally fractured strata in the lower Pennsylvanian Pottsville Formation in the eastern part of the Black Warrior basin, Alabama. Major fracture systems include orthogonal fractures, which consist of systematic joints in siliciclastic strata and face cleats in coal that strike northeast throughout the basin. Calcite and minor amounts of pyrite commonly fill joints in sandstone and shale and, less commonly, cleats in coal. Joint-fill calcite postdates most pyrite and is a weakly ferroan, coarse-crystalline variety that formed during a period of uplift and erosion late in the burial history. Pyrite forms fine to coarse euhedral crystals that line joint walls or are complexly intergrown with calcite. Stable-isotope data reveal large variations in the carbon isotope composition of joint- and cleat-fill calcite (-10.3 to + 24.3??? Peedee belemnite [PDB]) but only a relatively narrow range in the oxygen-isotope composition of this calcite (-16.2 to -4.1 ??? PDB). Negative carbon values can be attributed to 13C-depleted CO2 derived from the oxidation of organic matter, and moderately to highly positive carbon values can be attributed to bacterial methanogenesis. Assuming crystallization temperatures of 20-50??C, most joint- and cleat-fill calcite precipitated from fluids with ??18O ratios ranging from about -11 to +2 ??? standard mean ocean water (SMOW). Uplift and unroofing since the Mesozoic led to meteoric recharge of Pottsville strata and development of freshwater plumes that were fed by meteoric recharge along the structurally upturned, southeastern margin of the basin. Influxes of fresh water into the basin via faults and coalbeds facilitated late-stage bacterial methanogenesis, which accounts for the high gas content in coal and the carbonate cementation of joints and cleats. Diagenetic and epigenetic minerals can affect the transmissivity and storage capacity of joints and cleats, and they appear to contribute significantly to interwell heterogeneity in the Pottsville Formation. In highly productive coalbed methane fields, joint- and cleat-fill calcite have strongly positive ??13C values, whereas calcite fill has lower ??13C values in fields that are shut in or abandoned. Petrographic analysis and stable-isotope geochemistry of joint- and cleat-fill cements provide insight into coalbed methane reservoir quality and the nature and extent of reservoir compartmentalization, which are important factors governing methane production.

  7. U sbnd Pb, Pb sbnd Pb and Sm sbnd Nd dating of authigenic monazite: implications for the diagenetic evolution of the Welsh Basin

    Science.gov (United States)

    Evans, Jane; Zalasiewicz, Jan

    1996-11-01

    Authigenic monazite nodules from Silurian turbiditic rocks in the central Welsh Basin are zoned with respect to Nd isotope composition. The cores are relatively radiogenic, and the rim-to-core trend projects toward the composition of associated, very early authigenic, apatite concretions. These authigenic phases therefore equilibrated with changing fluid composition as they formed. The apatites and the monazite nodule cores may have included significant Nd from organic matter or seawater, whereas the REEs in the outer parts of the monazite nodules were derived from clastic detritus. The apparent Sm sbnd Nd 'age' obtained from these phosphates is a mixing line, which gives an Ordovician age for these Silurian rocks. The U sbnd Pb isotope system does not show similar trends, and shows promise as an alternative method for dating such phosphates: a date of 417 ± 11 Ma 2? (MSWD = 107) agrees well with recent estimates of the time of the diagenetic, smectite-illite transition in the rocks of this study. A Pb sbnd Pb isochron gave an age of 422 ± 24 Ma 2? (MSWD = 0.9) this shows that the Pb is in isotopic equilibrium and is undisturbed, and that the elevated MSWD of the U sbnd Pb regression is caused by slight subsequent mobility in the U sbnd Pb system. The event dated by the monazite is probably compactional dewatering during accelerated mid-Silurian sediment loading in the central Welsh Basin.

  8. Ages of detrital zircon from siliciclastic sucessions of the Brasilia belt, southern border of Sao Francisco craton: Implications for the evolution of proterozoic basins

    International Nuclear Information System (INIS)

    The determination of the age distribution of detrital zircon suites from greenschist and amphibolite facies metassedimentary rocks using 207Pb/206Pb laser-ablation inductively couple plasma mass spectometry (LA-ICPMS) was previously discussed by Machado and Gauthier (1996) and is an useful tool on determinating the ages interval of the source area. Although 207Pb/206Pb ages are, in principle, mimimum ages, Feng et al. (1993) and Machado and Gauthier (1996) showed that these ages are identical within error to U-Pb ages. The advantage of the method for sedimentary provenance studies is that the number of grains that can be analysed per day (ca. 50) on the same sample, providing a stastically meaningful age distribution. The most significant limitations of the method used in this work are the inability to yield reliable U-Pb values and the large analytical error of, at least, 1-10%. Neverthless, in provenance studies high precision are not required. In this work we report ages of detrital zircon from from lower greenschist metamorphic facies quartzites from the Proterozoic Sao Joao del Rei and Andrelandia basin successions. The data yield information about the ages of the source areas and provide an approach for constraining sedimentation ages in these basins (au)

  9. 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.

  10. 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.

  11. Finite element modelling of the pull-apart formation: implication for tectonics of Bengo Co pull-apart basin, southern Tibet

    Directory of Open Access Journals (Sweden)

    Ganesh Raj Joshi

    2010-06-01

    Full Text Available The tectonic deformation and state of stress are significant parameters to understand the active structure, seismic phenomenon and overall ongoing geodynamic condition of any region. In this paper, we have examined the state of stress and crustal deformation during the formation of the Beng Co pull-apart basins produced by an enéchelon strike-slip fault systems using 2D Finite Element Modelling (FEM under plane stress condition. The numerical modelling technique used for the experiments is based on FEM which enables us to analyze the static behavior of a real and continues structures. We have used three sets of models to explore how the geometry of model (fault overlap and pre-existing weak shear zone and applied boundary conditions (pure strike-slip, transpressional and transtensional influence the development of state of stress and deformation during the formation of pull-apart basins. Modelling results presented here are based on five parameters: 1 distribution, orienttation, and magnitude of maximum (?H max and minimum (?H max horizontal compressive stress 2 magnitude and orientation of displacement vectors 3 distribution and concentration of strain 4 distribution of fault type and 5 distribution and concentration of maximum shear stress (?H max contours. The modelling results demonstrate that the deformation pattern of the en-échelon strike-slip pull-apart formation is mainly dependent on the applied boundary conditions and amount of overlap between two master strike-slip faults. When the amount of overlap of the two master strike-slip faults increases, the surface deformation gets wider and longer but when the overlap between two master strike-slip faults is zero, block rotation observed significantly, and only narrow and small surface deform ation obtained. These results imply that overlap between two master strike-slip faults is a significant factor in controlling the shape, size and morphology of the pull-apart basin formation. Results of numerical modelling further show that the pattern of the distribution of maximum shear stress (?max contours are prominently depend on the amount of overlap between two master strike-slip faults and applied boundary conditions. In case of more overlap between two masters strike-slip faults, ? max mainly concentrated at two corners of the master faults and that reduces and finally reaches zero at the centre of the pull-apart basin, whereas in case of no overlap, ?max largely concentrated at two corners and tips of the master strike-slip faults. These results imply that the distribution and concentration of the maximum shear stress is mainly governed by amount of overlap between the master strike-slip faults in the en-échelon pull-apart formation. Numerical results further highlight that the distribution patterns of the displacement vectors are mostly dependent on the amount of overlap and applied boundary conditions in the en-échelon pull-apart formation.

  12. Natural CO2 migrations in the South-Eastern Basin of France: implications for the CO2 storage in sedimentary formations

    International Nuclear Information System (INIS)

    Study of natural CO2 analogues brings key informations on the factors governing the long term stability/instability of future anthropogenic CO2 storages. The main objective of this work, through the study of cores from V.Mo.2 well crosscutting the Montmiral natural reservoir (Valence Basin, France), is to trace the deep CO2 migrations in fractures. Petrographic, geochemical and micro-thermometric studies of the V.Mo.2 cores were thus performed in order: 1) to describe the reservoir filling conditions and 2) to detect possible CO2-leakage through the sediments overlying the reservoir. Fluid inclusions from the Paleozoic crystalline basement record the progressive unmixing of a hot homogeneous aquo-carbonic fluid. The Montmiral reservoir was therefore probably fed by a CO2-enriched gas component at the Late Cretaceous-Paleogene. The study of the sedimentary column in V.Mo.2 well, demonstrates that the CO2 did not migrate towards the surface through the thick marly unit (Domerian-Middle Oxfordian). These marls have acted as an impermeable barrier that prevented the upward migration of fluids. Two main stages of fluid circulation have been recognized: 1) an ante- Callovian one related to the Tethysian extension 2) a tertiary stage during which the upper units underwent a karstification, with CO2 leakage related but which remained confined into the deeper parts of the Valence Basin. Since the Paleogene, the Montmiral reservoir has apparently remained stable, despite the Pyrenean and alpine orogeneses. This is mainly due to the efficient seal formed by the thick marly levels and also to the local structuration in faulted blocks which apparently acted as efficient lateral barriers. (author)

  13. Tectonic setting of the Late Triassic volcaniclastic series of the Luang Prabang Basin, Laos, and geodynamic implications from the Triassic to Jurassic in SE Asia

    Science.gov (United States)

    Rossignol, Camille; Bourquin, Sylvie; Dabard, Marie-Pierre; Hallot, Erwan; Poujol, Marc; Nalpas, Thierry

    2014-05-01

    The Luang Prabang Basin, located on the eastern margin of the Indochina block, is mainly composed of volcaniclastic continental deposits. The interpretation of U-Pb zircon geochronological dates shows that volcanism is contemporaneous with the sedimentation during the Late Triassic (c.a. 225 to 215 Ma; Blanchard et al., 2013, J. Asian Earth Sci., 70-71; 8-26). At the same time, volcanism is also known along the Eastern margin of the Indochina block (present day Thailand). There are currently two main contrasting interpretations concerning the tectonic setting related to these volcanic events: are they arc-related (e.g. Barr et al., 2006, J. Geol. Soc. London, 163; 1037-1046) or post collisional (e.g. Srichan et al., 2009, Island Arc, 18; 32-51)? We have performed geochemical analysis on both sedimentary and volcanic rocks of the Luang Prabang Basin in order to evaluate the relationships between the volcanic events and to propose a geodynamic interpretation. The geochemical characteristics of the Luang Prabang Late Triassic volcaniclastic and volcanic rocks are compatible with a volcanic arc setting. The confrontation of these results with the stratigraphic evolution of the eastern margin of the Indochina block leads to reconsider the Late Triassic to Jurassic geodynamic evolution of this area. Arc-related volcanism seems to occur during nearly the whole Triassic, implying a subduction of the Paleotethys beneath the Indochina block. As the stratigraphic record of north-eastern Thailand and western Myanmar shows an important stratigraphic gap spanning from the Early to the Middle Jurassic, the collision between the Indochina and the Sibumasu blocks likely occurred at that period.

  14. The variability of vertical structure of precipitation in Huaihe River Basin of China: Implications from long-term spaceborne observations with TRMM precipitation radar

    Science.gov (United States)

    Cao, Qing; Qi, Youcun

    2014-05-01

    The current study investigates the variability of vertical structure of precipitation in the Huaihe River Basin (HRB) of China. The precipitation characteristics have been revealed by the long-term observations of vertical profile of reflectivity (VPR) from the first spaceborne precipitation radar (PR) onboard the National Aeronautics and Space Administration (NASA)'s Tropical Rainfall Measuring Mission (TRMM) satellite. This study has statistically analyzed the latest TRMM 2A-23 and 2A-25 products (version 7, released in 2012) with ˜15 years time span (from 11 December 1997 to 19 August 2012). First, the spatial and seasonal variations of storm height and freezing level have been investigated. The results show a climatological relation connecting the storm height with the rainfall rate in HRB. Second, mean VPRs have been studied for the stratiform and convective precipitation. The VPR variability has been analyzed for different seasons and rain intensities. Third, the characteristics of rain intensification and weakening in the vertical direction have been examined by the statistical analysis of VPR slope below the melting layer. The results show that the rainfall tends to be reduced (or intensified) with the height changing downward in the light (or moderate and heavy) precipitating clouds, no matter stratiform or convection. Finally, the S-band climatological VPRs have been characterized by converting the VPR from Ku-band to S-band. Considering the wide application of national radar network for weather surveillance in China, the developed S-band climatological VPRs can be potentially applied in a VPR correction scheme to improve the ground radar-based quantitative precipitation estimation (QPE) in this river basin.

  15. 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 ofs 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)

  16. Abnormal organic-matter maturation in the Yinggehai Basin, South China Sea: Implications for hydrocarbon expulsion and fluid migration from overpressured systems

    Science.gov (United States)

    Hao, F.; Li, S.; Dong, W.; Hu, Z.; Huang, B.

    1998-01-01

    Three superimposed pressure systems are present in the Yinggehai Basin, South China Sea. A number of commercial, thermogenic gas accumulations have been found in an area in which shale diapirs occur. Because the reservoir intervals are shallow and very young, they must have filled with gas rapidly. The thick (up to 17 km) Tertiary and Quaternary sedimentary succession is dominated by shales, and is not disrupted by major faulting in the study area, a factor which seems to have had an important effect on both hydrocarbon generation and fluid migration. Organic-matter maturation in the deepest, most overpressured compartment has been significantly retarded as a result of the combined effects of excess pressure, the presence of large volumes of water, and the retention of generated hydrocarbons. This retardation is indicated by both kerogen-related parameters (vitrinite reflectance and Rock-Eval T(max)); and also by parameters based on the analysis of soluble organic matter (such as the C15+ hydrocarbon content, and the concentration of isoprenoid hydrocarbons relative to adjacent normal alkanes). In contrast to this, organic-matter maturation in shallow, normally-pressured strata in the diapiric area has been enhanced by hydrothermal fluid flow, which is clearly not topography-driven in origin. As a result, the hydrocarbon generation 'window' in the basin is considerably wider than could be expected from traditional geochemical modelling. These two unusual and contrasting anomalies in organic-matter maturation, together with other lines of evidence, suggest that there was a closed fluid system in the overpressured compartment until shale diapirs developed. The diapirs developed as a result of the intense overpressuring, and their growth was triggered by regional extensional stresses. They served as conduits through which fluids (both water and hydrocarbons) retained in the closed system could rapidly migrate. Fluid migration led to the modification of the thermal regime and the enhancement of organic maturation, as well as the accumulation of commercial volumes of gas in a relatively short time interval.Three superimposed pressure systems are present in the Yinggehai Basin, South China Sea. To date, a number of commercial, thermogenic gas accumulations have been found in an area in which shale diapirs occur. In fact, two unusual and contrasting anomalies in organic-matter maturation have been documented. These two anomalies, together with other lines of evidence, suggest that there was a closed fluid system in the overpressured compartment until shale diapirs developed. The diapirs developed as a result of intense overpowering, and their growth was triggered by regional extensional stresses. They served as conduits through which fluids retained in the closed system could rapidly migrate. Fluid migration led to the modification of the thermal regime and the enhancement of organic maturation, as well as the accumulation of commercial volumes of gas in a relatively short time interval.

  17. Clay mineral assemblages of terrestrial records (Xining Basin, China) during the Eocene-Oligocene climate Transition (EOT) and its environmental implications

    Science.gov (United States)

    Zhang, C.; Guo, Z.

    2013-12-01

    The Eocene-Oligocene Transition (EOT) between ~34.0 and 33.5 million years ago, where global climate cooled from 'greenhouse' to 'icehouse' at ~33.5 Ma ago, is one of the great events during Cenozoic climate deterioration. In contrast to the marine records of the EOT, significantly less research has focused on the continental climate change during this time, particularly in inner Asia. We present a comprehensive study of the upper Eocene to lower Oligocene succession with regular alternations of laterally continuous gypsum/gypsiferous layers and red mudstone beds in Tashan section of Xining Basin, which is located at the northeastern margin of the Tibetan Plateau. Clay minerals, which were extracted from this succession, were analyzed qualitatively and semi-quantitatively by using X-ray differaction (XRD). Base on detailed magnetostratigraphic time control, clay mineral compositions of this succession (33.1-35.5 Ma) are compared with open ocean marine records and Northern Hemisphere continental records to understand the process and characteristics of Asian climate change before, during and after EOT. Our results indicate that illite is the dominant clay mineral with less chlorite and variable smectite. Multi-parameter evidence suggests that the source areas of detrital inputs in Tashan have not changed and climate is the main control for the composition of the clay fraction. The characteristics of clay mineral concentrations suggest warm and humid fluctuations with cold and dry conditions and intense of seasonality during ~35.5-34.0 Ma in inner Asian. This changed to cold and dry condition at ~34 Ma and remained so from ~34-33.1 Ma. The comparisons between continental and marine records indicate that the climate changes experienced in the Xining basin region are more consistent with Northern Hemisphere rather than open oceans records. This indicates that paleoclimate changes for inner Asian before, during and after EOT was not controlled by Antarctic ice growth, but may be due to atmospheric cooling linked to the existence and expansion of Northern Hemisphere glaciation.

  18. Genetic origins of marine gases in the Tazhong area of the Tarim basin, NW China: Implications from the pyrolysis of marine kerogens and crude oil

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Hui; Xiao, Xianming; Guo, Liguo; Yang, Liguo [State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Wilkins, Ronald W.T. [CSIRO Petroleum, P. O. Box 136, North Ryde, NSW (Australia); Gan, Huajun [Department of Coal and Coalbed Methane Engineering, Faculty of Earth Resources, China University of Geosciences, Wuhan 430074 (China)

    2010-05-01

    Although abundant natural gases have been discovered in Carboniferous and Ordovician reservoirs in the Tazhong area, central Tarim basin, their genetic origins is still an open question because of significant variations in chemical and carbon isotopic compositions. In the present study, three samples representing the possible gas sources were pyrolyzed using sealed gold tubes to investigate their gas potentials, and chemical and carbon isotopic signatures. The samples were a crude oil, a low maturity kerogen and a high maturity kerogen. The results show that the chemical and isotopic compositions of gaseous pyrolysates from the three samples are quite different. Generally, the gases from oil cracking are compositionally wetter and isotopically lighter than those from kerogen cracking at similar thermal levels. The large quantities of methane experimentally observed in oil cracking gases are mainly associated with the re-cracking of wet gases at very high maturity levels. Methane in gases derived from kerogen, especially high maturity kerogen, in contrary, is mainly generated by the demethylation reaction. The diagrams of {delta}{sup 13}C{sub 1} vs. {delta}{sup 13}C{sub 2}-{delta}{sup 13}C{sub 3} and C{sub 2}/C{sub 3} vs. {delta}{sup 13}C{sub 2}-{delta}{sup 13}C{sub 3}, along with natural gas plots, have proven to be a very effective tool in the genetic interpretation of natural gases from kerogen and oil cracking in the Tarim basin. Their combined application shows that two types of gas source can be identified in the Tazhong area. The first type is oil cracking gas, mainly discovered in Carboniferous reservoirs of the central fault horst area, but also partly in Ordovician reservoirs, such as in the wells TZ45, TZ44b and TZ 16. The other is kerogen cracking gas occurring largely in Ordovician reservoirs, especially in the North Slope area. The two types of gases, however, are mixed in many reservoirs as their generation is overlapped in time and/or space. This mixing process is especially obvious for methane. (author)

  19. 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.

  20. 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 fromindigenous 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.

  1. 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 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

  2. 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-Cub> 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.

  3. Regional importance of post-6 M.Y. old vocanism in the southern Great Basin: Implications for risk assessment of volcanism at the proposed Nuclear Waste Repository at Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    This report summarizes our activities during the period July 1, 1987 to June 30, 1988. Our goal was to develop an understanding of late-Miocene and Pliocene volcanism in the Great Basin by studying late-Tertiary volcanic rocks to the north and south of the Nevada Test Site (Figure 1). We especially concentrated on detailed stratigraphic studies and geochemistry to determine the nature of chemical changes during the lifetime of a volcanic field, and on structural studies to determine the nature of the structures that control vent location. Also, K-Ar age dating provided important new information on the duration of activity at a single volcanic center. Geologic studies were concentrated in the Fortification basalt field in southern Nevada and in the Reveille Range in central Nevada. Our studies provide three important conclusions that have implications for volcanism about the proposed Nuclear Waste Repository at Yucca Mountain. There are no easily recognized geochemical characteristics that signify the termination of volcanism. The location of vent areas of basaltic volcanoes are not necessarily controlled by pre-existing structures. Volcanism at an individual basaltic center may last as long as 500,000 years. 32 refs., 34 figs., 6 tabs

  4. Stable oxygen isotope of ostracods in recent sediments of Lake Gahai in the Qaidam Basin, northwest China: The implications for paleoclimatic reconstruction

    Science.gov (United States)

    Li, Xiangzhong; Liu, Weiguo; Xu, Liming

    2012-08-01

    The oxygen isotopic composition of ostracod shells in lakes has been used as a useful indicator in palaeolimnological research and has provided some important contributions to the understanding of lacustrine systems. Usually, the oxygen isotopic compositions of ostracods from the lake sediments are interpreted as changes in effective precipitation, temperature and evaporation/input water ratio in a sub-arid or arid area. Here, we compare a 150-year-long oxygen-isotope record that was derived from ostracod carbonate from the sediments of Lake Gahai in the Qaidam Basin with meteorological data (precipitation) and tree-ring evidence for changing precipitation. Our results show that the oxygen isotopic compositions of ostracod shells are related to precipitation over the past 150 years. In general, increased precipitation accompanied a shift to less positive ?18O values in the lake water, and thus in the ostracod shells, whereas decreased precipitation coincided with the opposite in Lake Gahai over the past 150 yr. Therefore, we conclude that the oxygen isotopic compositions of ostracod shells can be used to indicate changes in precipitation over a short time scale in Lake Gahai.

  5. THE GULLY FORMATION PROCESSES OF THE BASINS AND THEIR IMPLICATIONS ON THE SLOPES STABILITY, A RELIEF EVOLUTION MODEL ON THE BRAZILIAN SAVANNA DOMAIN

    Directory of Open Access Journals (Sweden)

    Claudete Ap. Dallevedove Baccaro

    2005-05-01

    Full Text Available This article brings on the results of specific studies over erosion carried out for twenty years by a crew of researchers of Universidade Federal de Uberlândia. The researches at all took place in Uberlândia, Monte Carmelo, Iraí de Minas counties and others, prior focusing the basins of Douradinho at Uberlândia, Pantaninho and Divisa at Iraí de Minas and Boa Vista at Prata.This Triângulo Mineiro specific area has been through several geographical changes over the twentieth century implying alteration on its landscape structure. According to this, the need of knowing the processes dynamic as well as the diagnoses methods and also how toelaborate bating corrections and means to recover degraded areas has become extremely necessary. The main goal was the identification of either the mechanisms or the conditions stablishers responsible for erosion processes.“The tropical environment is characterized by a damaged landscape composed by potentially affected areas and others recently occupied which present initial effects. Both the areas need planning research. Whenever those environments get altered by human action, their fragilities show up” (Baccaro, 1994:19.

  6. Hydraulic Communication Between Coalbeds and Overlying Sands in the Powder River Basin, Wyoming and Montana: Implications for Re-injection of Coalbed Methane Water

    Science.gov (United States)

    Ross, H. E.; Zoback, M. D.

    2006-12-01

    Coalbed methane (CBM) production in the Powder River Basin (PRB) is associated with the production of large volumes of CBM water. CBM water from the PRB has high saline and sodium contents, making it unsuitable for agriculture and environmentally damaging. One option for the disposal of CBM water is re-injection into aquifers, but for injection to be feasible the porosity and permeability of the sands needs to be high, the pore pressure needs to be low, and the aquifer cannot be in hydraulic communication with the coalbeds. In order to determine if pore pressures in the aquifers are low enough to allow for significant CBM water re-injection and to determine whether the coals and sands are in hydraulic communication with each other we have calculated pore pressures in 220 wells that monitor water levels in coalbeds and adjacent sands within the PRB. All 220 wells have pore pressures below hydrostatic pressure, implying that re-injection of CBM water should be feasible. However, by analyzing pore pressure changes with time for both the coals and their overlying sands, we find that sands less than 100 ft from coal appear to be in communication with the coalbed. Therefore, re- injection of CBM water should be carried out in sands further than 100 ft from adjacent coalbeds. It also follows that CO2 sequestration in PRB coalbeds should not be carried out in areas where sands and coals are hydraulically connected, as potential leakage pathways for CO2 maybe present.

  7. 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

  8. 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.

  9. 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.

  10. Biomarker characterization of the record of the OAE1a (early Aptian) in Betic and Cantabrian basins (Spain)-Sedimentary implications

    Science.gov (United States)

    Quijano, María. Luisa; Castro, José Manuel; Pancost, Richard D.; de Gea, Ginés. A.; Najarro, María.; Aguado, Roque; Rosales, Idoia; Martín-Chivelet, Javier

    2010-05-01

    Molecular analyses of sedimentary organic matter are powerful tools in assessing the origin of organic matter and its thermal maturity as well as constraining ancient environmental conditions, such as as marine productivity, anoxia in bottom waters or the photic zone and sea surface temperatures. This communication presents the study of four sections recording the OAE1a (early Aptian) in Spain, which are located in two broad basins respectively located in the South and the North of Iberia: the Southern Iberian Palaeomargin (Carbonero - CAB, La Frontera - XF and Cau - CAU sections) and the Cantabrian Basin (Puente Nansa - PN section). These sections represent depositional settings ranging from platform (CAU, PN) to pelagic environments (CAB, XF). C-isotope profiles and biostratigraphic data are used to define the interval corresponding to the OAE 1a. Here we focus on the biomarker composition of the organic-rich facies, and the integration of these data with the sedimentology, stratigraphy and paleogeography. The study has been based mainly upon the analysis of samples with Gas Chromatography-Mass Spectrometry (GCMS). Four main groups of compounds are present in all sections: n-alkanes, isoprenoids, hopanes and steranes. n-Alkanes and isoprenoids (pristane and phytane) are dominant in most samples. To facilitate interpretation of these distributions, we have calculated the TAR (terrestrial aquatic ratio derived from the ratio of long to short chain compounds) and also the OEP (odd over even predominance of n-alkanes). The ratio of pristane to phytane and various isoprenoid/n-alkanes ratios have also been calculated. The hopanes are represented by a range of C27 to C35 components, with the specific isomers varying amongst the sections due to differences in thermal maturity. Steranes occur as a range of C27, C28 and C29 isomers, whereas diasteranes only occur in the most thermally mature section (CAB). Other compounds of interest include gammacerane and dinosterane. The analysis of the data shows interesting differences between the studied sections, of which thermal maturity appears to be a first order control. The n-alkane distribution (OEP) and sterane and hopane epimer ratios (20S/(20R+20S) steranes and 22S/(22R+22S) hopanes) all reveal that the CAB section is thermally mature, whereas the nearby XF section is very immature. CAU section shows a very low maturity, and PN shows intermediate values. The isoprenoids/n-alkanes ratios also present different values between the four sections. These differences help constrain the paleogeograhic and sedimentary interpretation of the studied sections. Organic matter is derived from a range of terrestrial, marine and bacterial sources. Maturity varies strongly, even between nearby sections (CAB and XF), probably in relation with tectonic and volcanic synsedimentary activity. The distribution of n-alkanes (TAR ratios), would indicate a trend from predominance of marine plants in the CAB samples, towards a higher proportion of continental input to XF, PN and CAU sections, consistent with the paleogeography, but observed differences in thermal maturity could also account for this trend. The dominance of the C29 isomers in steranes in all sections would indicate a contribution from higher plants. The presence of gammacerane as well as a high C29/C30 hopane ratios could indicate water column stratification and anoxia at the water/sediment interface, respectively, although these features are not always present and other proxies for anoxia (e.g. isorenieratene derivatives) have not been detected with the method used. The vertical trends observed reveal notable changes through time; therefore, a higher resolution study along the sections will provide new evidence for furthering our understanding of the causes and extent of OAE1a. This work is a contribution of the University of Jaén research project UJA-07-16-41, and Research Group of the Junta de Andalucía (Spain) RNM-200.

  11. 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)

  12. Hydrothermal activity and its paleoecological implications in the latest Miocene to Middle Pleistocene lacustrine environments of the Baza Basin (Betic Cordillera, SE Spain)

    Science.gov (United States)

    García-Aguilar, José Manuel; Guerra-Merchán, Antonio; Serrano, Francisco; Palmqvist, Paul; Flores-Moya, Antonio; Martínez-Navarro, Bienvenido

    2014-07-01

    The continental sedimentary record of the Baza Basin (Guadix-Baza Depression, Betic Cordillera, SE Spain) shows six sedimentary units of lacustrine origin deposited from the latest Miocene to the Middle Pleistocene. Depending on the interval considered, the lacustrine deposits are mainly composed of marls, carbonates or gypsiferous evaporites, showing lithological, mineralogical and geochemical features (i.e., magnesium, strontium and sulfur contents, celestine deposits and travertine growths) that are evidence of intense, tectonically-induced hydrothermal activity. According to the high concentrations of strontium and sulfur as well as the abundance of travertines and magnesium clays, the supply of hot waters was greater during the Zanclean, the Gelasian and the Calabrian, as a result of tectonic activity. Hydrothermal activity has continued until the present time and is responsible of the hot springs that are nowadays active in the Guadix-Baza Depression. The paleoenvironmental consequences of these sublacustrine hot springs were that during some intervals the lakes maintained a relatively permanent water table, not subject to periodic desiccations in the dry season, and warmer temperatures throughout the year. This resulted in a high level of organic productivity, especially for the Calabrian, which allowed the development of a rich and well diversified mammalian community, similar to those of modern African savannas with tree patches. In this mild environment, the permanent water sheet favored the presence of drought intolerant megaherbivores such as the giant extinct hippo Hippopotamus antiquus. The high standing crop biomass of ungulates resulted in the availability of abundant carcasses for scavengers such as hyenas and hominins, which explains the very high densities of skeletal remains preserved in the sediments distributed along the lake surroundings.

  13. Spatial distributions of core and intact glycerol dialkyl glycerol tetraethers (GDGTs) in the Columbia River basin, Washington: Insights into origin and implications for the BIT index

    Science.gov (United States)

    French, David W.; Huguet, Carme; Wakeham, Stuart; Turich, Courtney; Carlson, Laura T.; Ingalls, Anitra E.

    2015-04-01

    Branched and isoprenoid glycerol dialkyl glycerol tetraethers (GDGTs) are used to reconstruct carbon flow from terrestrial landscapes to the ocean in a proxy called the branched vs isoprenoid tetraether index, or BIT Index. The index is based on analysis of core GDGTs from non-living material that originate from the cell membranes of bacteria living in soils and archaea living primarily in the marine environment. However, uncertainty in the identity and location of branched GDGTs (BrGDGTs) producing organisms and the likely production of isoprenoid GDGTs (IsoGDGTs) in terrestrial environments hinders interpretation of the BIT Index. Since BrGDGTs remain our only tool to study BrGDGT producing organisms, it is particularly important to use the intact form of BrGDGTs, present in living cells, to infer organism distributions. In situ production within riverine, lacustrine, and marine environments is currently thought to be possible, yet few measures of intact BrGDGTs (I-BrGDGTs) are available to confirm this. Here we assess the spatial distribution of both core and intact GDGTs throughout the Columbia River basin and nearby areas in Washington and Oregon in order to elucidate source environments for these lipids. The presence of I-BrGDGTs throughout the studied soils, rivers and estuaries suggests in situ production across the continuum from soil to marine environments. Likewise, intact crenarchaeol, the marine endmember isoprenoidal GDGT used in the BIT index, was present in all samples. Widespread production of each GDGT class along terrestrial carbon transport paths likely alters the BIT Index along this continuum. The core to intact GDGT ratios and the weak correlation between I-GDGT derived BIT values and carbon isotope signatures suggest a mixture of allocthonous and autochthonous sources of GDGTs in riverine and marine environments. Our findings highlight the need for further work into the provenance of GDGTs to improve the BIT index and other environmental proxies that rely on these compounds.

  14. Chemistry of sands from the modern Indus River and the Archean Witwatersrand basin: Implications for the composition of the Archean atmosphere

    International Nuclear Information System (INIS)

    Both the Indus River and the Witwatersrand basin contain sand with grains of detrital uraninite. Because this mineral is easily oxidized, its presence in Archean strata as a detrital particle has been used as evidence for a low-oxygen atmosphere before 2.5 Ga. However, its presence in modern sand from the Indus River system has been used to argue that detrital uraninite does not provide information about the oxygen concentration of Earth's early atmosphere. Petrographic and chemical study of sand from these two sources reveals differences that suggest the modern Indus sand cannot be used as an analog for the Archean Witwatersrand occurrences. The Witwatersrand quartzites are depleted in Ca, Mg, and Na, indicating that the original sand from which they formed had been subjected to intense weathering. The chemical index of alteration (CIA), a commonly used indicator of degree of weathering, yields an average value of about 0.80 for Witwatersrand quartzites, comparable to modern tropical streams such as the Orinoco that drain deeply weathered terrains under tropical conditions (CIA=0.75). In contrast, the CIA for Indus sand is 0.45, indicating virtually no chemical weathering. The significance of Archean quartz-pebble conglomerates is not just that they contain unstable detrital phases like uraninite and pyrite, but that these particles are associated with rocks whose compositions suggest intense weathering. These conglomerates must have been subjected to intense weatherust have been subjected to intense weathering under tropical conditions, either in their source area or at the site of deposition, and the preservation of minerals like uraninite such conditions is indeed strong evidence for a low-oxygen atmosphere

  15. 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.

  16. Evaluation of triclosan and triclocarban at river basin scale using monitoring and modeling tools: implications for controlling of urban domestic sewage discharge.

    Science.gov (United States)

    Zhao, Jian-Liang; Zhang, Qian-Qian; Chen, Feng; Wang, Li; Ying, Guang-Guo; Liu, You-Sheng; Yang, Bin; Zhou, Li-Jun; Liu, Shan; Su, Hao-Chang; Zhang, Rui-Quan

    2013-01-01

    Triclosan (TCS) and triclocarban (TCC) are two commonly used personal care products. They may enter into aquatic environments after consumption and pose potential risks to aquatic organisms. We investigated the occurrence and fate of TCS and TCC in five large rivers (the Liao River, Hai River, Yellow River, Zhujiang River and Dongjiang River) in China, and compared the monitoring data with the predicted results from Level III fugacity modeling. TCS and TCC were detected in the five large rivers with the detection frequencies of 100% or close to 100% in surface water and sediments of almost every river. TCS and TCC were found at concentrations of up to 478 ng/L and 338 ng/L in surface water, and up to 1329 ng/g and 2723 ng/g in sediments. Cluster analysis indicated that the sites with higher concentrations were usually located in or near urban area. Meanwhile, principal component analysis also suggested that the mass inventories of TCS and TCC in water and sediment were significantly influenced by the factors such as the total or untreated urban domestic sewage discharge at river basin scale. The concentrations and mass inventories from the fugacity modeling were found at the same order of magnitude with the measured values, suggesting that the fugacity modeling can provide a useful tool for evaluating the fate of TCS and TCC in riverine environments. Both monitoring and modeling results indicated that the majority of mass inventories of TCS and TCC were stored into sediment, which could be a potential pollution source for river water. The wide presence of TCS and TCC in these large rivers of China implies that better controlling of urban domestic sewage discharge is needed. PMID:23127624

  17. Variations in Composition and Preservation of Peat Deposited Since 27 ka in the Baoxiu Basin, Southwestern China: Implications for Environmental and Climatic Changes

    Science.gov (United States)

    Lu, Y.; Sun, Y.; Meyers, P. A.; Weng, H.

    2004-12-01

    Multi-proxy organic geochemical paleoclimate records have been obtained from a 200-cm peat core extending back to about 27 ka cal from the Baoxiu Lake Basin, Yunnan Province of southwestern China. Relatively low del 13C values (-26.3 to -24.3 per mil) of total organic carbon (TOC) and of n-fatty acids (-30.4 to -33.0 per mil), high TOC/TN ratios (17 to 64), and the presence of p-hydroxyphenyl, guaiacyl, and syringyl phenylpropanyl lignin units in pyrolysates show that the source of organic matter is dominated by terrestrial C3 grasses (herbaceous angiosperms) throughout this peat profile. Decomposition of peat is indicated by shortening of alkyl side-chains of methoxyphenols, an increase of oxidation products, and demethylation of methoxy groups of the lignin/polyphenol fraction. Lower amounts of these decomposition proxies below 100 cm indicate good preservation of peat from 26.8 to 22.6 ka and imply good reliability of climatic information derived from this time range in the peat profile. From 26.8 to 23.3 ka , lower inputs of terrestrial plants and lower aquatic productivity are suggested by relatively low concentrations of TOC and phosphorus, mirroring decreased precipitation. Relatively heavier carbon isotopic compositions of plant wax n-fatty acids (C24 - C30) indicate larger contributions of C4 plants, providing a further hint of dry climate. Intermediate del 13C values of TOC and of mid-chain n-fatty acids (C20 - C22) result from an overprint of organic matter from aquatic algae. From 23.3 to 22.6 ka, a rapid increase of precipitation and a resultant C3 land-plant expansion is documented by maxima in concentrations of TOC and phosphorus, a minimum in TOC del 13C, and relatively negative del 13C values of plant-wax n-fatty acids. Since 22.6 ka, climate reconstruction is not reliable because of disturbance of the peat layers. The disturbance is most likely caused by human activities, a conclusion that is supported by a rapid increase in peat decomposition as indicated by more phenol proxies and higher concentrations of phosphorus.

  18. Temperature-pressure conditions in coalbed methane reservoirs of the Black Warrior basin: Implications for carbon sequestration and enhanced coalbed methane recovery

    Science.gov (United States)

    Pashin, J.C.; McIntyre, M.R.

    2003-01-01

    Sorption of gas onto coal is sensitive to pressure and temperature, and carbon dioxide can be a potentially volatile supercritical fluid in coalbed methane reservoirs. More than 5000 wells have been drilled in the coalbed methane fields of the Black Warrior basin in west-central Alabama, and the hydrologic and geothermic information from geophysical well logs provides a robust database that can be used to assess the potential for carbon sequestration in coal-bearing strata.Reservoir temperature within the coalbed methane target zone generally ranges from 80 to 125 ??F (27-52 ??C), and geothermal gradient ranges from 6.0 to 19.9 ??F/1000 ft (10.9-36.2 ??C/km). Geothermal gradient data have a strong central tendency about a mean of 9.0 ??F/1000 ft (16.4 ??C/km). Hydrostatic pressure gradients in the coalbed methane fields range from normal (0.43 psi/ft) to extremely underpressured (carbon dioxide. However, reservoirs have potential for supercritical fluid conditions beyond a depth of 2480 ft (756 m) under normally pressured conditions. All target coal beds are subcritically pressured in the northeastern half of the coalbed methane exploration fairway, whereas those same beds were in the supercritical phase window prior to gas production in the southwestern half of the fairway. Although mature reservoirs are dewatered and thus are in the carbon dioxide gas window, supercritical conditions may develop as reservoirs equilibrate toward a normal hydrostatic pressure gradient after abandonment. Coal can hold large quantities of carbon dioxide under supercritical conditions, and supercritical isotherms indicate non-Langmiur conditions under which some carbon dioxide may remain mobile in coal or may react with formation fluids or minerals. Hence, carbon sequestration and enhanced coalbed methane recovery show great promise in subcritical reservoirs, and additional research is required to assess the behavior of carbon dioxide in coal under supercritical conditions where additional sequestration capacity may exist. ?? 2003 Elsevier Science B.V. All rights reserved.

  19. The Jurassic of Denmark and Greenland: The Lower–Middle Jurassic of the Anholt borehole: implications for the geological evolution of the eastern margin of the Danish Basin

    Directory of Open Access Journals (Sweden)

    Korsbech, Uffe

    2003-10-01

    Full Text Available This study of Upper Pliensbachian – Bajocian/Bathonian deposits in a borehole drilled on the island of Anholt, Denmark incorporates sedimentology, biostratigraphy (palynomorphs and foraminifera,palaeomagnetism and coal petrology. The studied succession records a gradual change from marine inner shelf storm-influenced clays to mainly terrestrial sands, clays, and lignite containing a flora ofmainly freshwater algae and pollen. The regression was initiated at the Pliensbachian–Toarcian boundary and marine influence ceased during Bajocian–Bathonian times; the regression thus took place earlier at Anholt than in the centre of the Danish Basin. The sediments in the Anholt borehole are referred to the Fjerritslev and Haldager Sand Formations. Although the Lower–Middle Jurassicboundary is commonly placed at the boundary between the two formations, our data indicate that at Anholt the upper Fjerritslev Formation (member F-IV is of Aalenian age. The Lower–Middle Jurassicboundary occurs close to the boundary between members F-III and F-IV of the Fjerritslev Formation.In contrast to other Lower–Middle Jurassic successions in the North Sea region, smectites of inferred volcanic origin are preserved in the Anholt section, suggesting limited burial and hence less intense diagenetic illitisation or chloritisation of smectites. A down-hole increase in diagenetic influence is reflected by the increase down-section both in the thermal stability of kaolinite and in the vitrinite reflectance. Kaolinite of inferred authigenic origin forms a white powder in the quartz-dominated sands of the Haldager Sand Formation; this kaolinite is thermally very unstable and is interpreted to be of late diagenetic, post-uplift origin. The vitrinite reflectance data indicate that the Jurassic formations have been exposed to thermal maturation corresponding to burial to a depth of 1000–1200 m below their present depth. Post-maturation uplift of the order of 1 km probably occurred partly during Late Cretaceous – Paleocene inversion in the Kattegat area and partly during Oligocene–Recent regional uplift, the latter being the most important of the two uplift phases. Palaeomagnetic data indicate that the main carrier of magnetic remanence is fine-grained magnetite. The stable remanence shows a pronounced inclination shallowing, which is attributed to post-depositional compaction.

  20. Water-table decline in the south-central Great Basin during the Quaternary Period; implications for toxic-waste disposal

    Science.gov (United States)

    Winograd, I.J.; Szabo, B. J.

    1986-01-01

    The distribution of vein calcite, tufa, and other features indicative of paleo-groundwater discharge, indicates that during the early to middle Pleistocene, the water table at Ash Meadows, in the Amargosa Desert, Nevada, and at Furnace Creek Wash, in east-central Death Valley, California, was tens to hundreds of meters above the modern water table, and that groundwater discharge occurred up to 18 km up-the-hydraulic gradient from modern discharge areas. Uranium series dating of the calcitic veins permits calculation of rates of apparent water table decline; rates of 0.02 to 0.08 m/1000 yr are indicated for Ash meadows and 0.2 to 0.6 m/1000 yr for Furnace Creek Wash. The rates for Furnace Creek Wash closely match a published estimate of vertical crustal offset for this area, suggesting that tectonism is a major cause for the displacement observed. In general, displacements of the paleo-water table probably reflect a combination of: (a) tectonic uplift of vein calcite and tufa, unaccompanied by a change in water table altitude; (b) decline in water table altitude in response to tectonic depression of areas adjacent to dated veins and associated tufa; (c) decline in water table altitude in response to increasing aridity caused by major uplift of the Sierra Nevada and Transverse Ranges during the Quaternary; and (d) decline in water altitude in response to erosion triggered by increasing aridity and/or tectonism. A synthesis of geohydrologic, neotectonic, and paleoclimatologic information with the vein-calcite data permits the inference that the water table in the south-central Great Basin progressively lowered throughout the Quaternary. This inference is pertinent to an evaluation of the utility of thick (200-600 m) unsaturated zones of the region for isolating solidified radioactive wastes from the hydrosphere for hundreds of millenia. Wastes buried a few tens to perhaps 100 m above the modern water table--that is above possible water level rises due to future pluvial climates--are unlikely to be inundated by a rising water table in the foreseeable geologic future. (Author 's abstract)

  1. New high precision U-Pb ages for the Vinchina Formation: Implications for the stratigraphy of the Bermejo Andean foreland basin (La Rioja province, western Argentina)

    Science.gov (United States)

    Ciccioli, P. L.; Limarino, C. O.; Friedman, R.; Marenssi, S. A.

    2014-12-01

    The Vinchina Formation is one of the thickest Cenozoic units related to the Andean orogeny in Argentina totaling more than 5100 m in thickness. Different ages, from Eocene to latest Miocene, have been postulated for this red-bed succession based on fission track, magnetostratigraphy and whole rock isotopic analyses. Two new high precision U-Pb zircon ages are reported herein for this unit. A maximum U-Pb age of 15.6 ± 0.4 Ma was obtained from detritic zircons collected from a thick tuffaceous interval of the Lower Member of the Vinchina Formation at La Cueva (Precordillera), while a depositional U-Pb age of 9.24 ± 0.034 Ma was derived from volcanic zircons collected from a thin tuff bed in the Upper Member at Quebrada de Los Pozuelos (Northwestern Sierras Pampeanas). At La Cueva, the Vinchina Formation unconformably overlies eolian sandstones of the Vallecito Formation and was divided into four units representing 1) deposits of high-sinuosity ephemeral rivers associated with 2) a playa-lake passing upwards to 3) low-sinuosity sandy ephemeral rivers and finally, 4) a gravelly-sandy braided plain. The tuffaceous level corresponding to unit 1 is located 280 m above the base of the formation. At Quebrada de Los Pozuelos, the Vinchina Formation unconformably overlies the Vallecito Formation and is covered by a deeply incised surface at the base of the Toro Negro Formation. We divided the Vinchina Formation into four units. Unit 1 represents sedimentation in shallow fluvial channels with sandy to muddy floodplains. Units 2 and 3 record sedimentation in braided, meandering and anastomosing rivers. Finally unit 4 represents deposition in braided and wandering fluvial systems. The sampled tuff is located within unit 4 at ?3470 m above the base of the formation. The new ages indicate that the bulk of the Vinchina Formation is Miocene in age but they do not preclude a longer time span for the sedimentation of the whole unit. Ages of the sampled volcanic zircons match an important episode of volcanism recorded in the Cerro Las Tórtolas Formation, located ?90 km to the west in the Andean Cordillera, but also the upper tuff could be related to the late Miocene Puna volcanism. Comparison of the new ages with previous chronological data suggests coetaneous sedimentation along different depocenters of the Bermejo basin (e.g., Vinchina and Talampaya depocenters in Western Sierras Pampeanas and La Troya depocenter and Huaco-Mogna sections in Precordillera) and strenghten the need for correlation among them. In addition the age of 15.6 ± 0.4 Ma constrains the end of the severe arid conditions recorded in the Sierras Pampeanas and Precordillera region.

  2. Implication for horizontally-elongated fluid flow inferred from heat flow measurements in the Iheya-North hydrothermal field, Okinawa Trough back-arc basin

    Science.gov (United States)

    Masaki, Yuka; Kinoshita, Masataka; Kawada, Yoshifumi

    2010-05-01

    The Okinawa Trough is a back-arc basin located in the southwestern part of Japan. It is considered to be in the initial stage of rifting of continental crust, and the activity generates volcanic edifices in this area, accompanied by hydrothermal circulation. The Iheya-North is one of the most active hydrothermal fields among them. As a proposed drilling site for the Integrated ocean Drilling Program, extensive geophysical surveys have been carried out including single-channel seismic imaging, and precise side-scan sonar imaging by using autonomous underwater vehicle 'Urashima' of Japan Agency for Marine-Science and Technology. In the recent few years, we have measured heat flow in and around the Iheya-North hydrothermal field to understand the spatial of hydrothermal circulation in detail. 78 measurements show that heat flow is higher than 10 W/m2 with in 0.5 km of the hydrothermal vent complex, that it gradually decrease eastward to < 1 W/m2, and that very low heat flow around 0.01 W/m2 is observed at 1.5 km east from the hydrothermal field. The average heat flow outside of Iheya-North is ~0.1 W/m2. The low heat flow to the east is most likely caused by an inward flow of seawater into the formation. Seismic and side-scan sonar images as well as piston core samples suggest an impermeable sediment layer to a few hundreds meters below the seafloor in this area. This sediment layer should work as a hydrological barrier to suppress flow through the seafloor, whereas seawater can penetrate into the formation at 1.5 km east of the hydrothermal field, where sidescan images suggest coars sediments on the seafloor. We infer that the hydrothermal circulation within the Iheya-North involves one with a horizontally-elongated scale (~1.5 km horizontal vs. ~a few hundreds meters vertical). We performed numerical calculations of fluid flow and heat transportation to give constraints on the depth of hydrothermal circulation, the magnitude of darcy velocity, and the permeability at depth. The simulated results will be compared with measured heat flow distribution and will be checked for the larger or smaller circulation scale proposed from heat flow or fluid geochemistry data.

  3. Geochemistry of the Cretaceous coals from Lamja Formation, Yola Sub-basin, Northern Benue Trough, NE Nigeria: Implications for paleoenvironment, paleoclimate and tectonic setting

    Science.gov (United States)

    Sarki Yandoka, Babangida M.; Abdullah, Wan Hasiah; Abubakar, M. B.; Hakimi, Mohammed Hail; Adegoke, Adebanji Kayode

    2015-04-01

    The Cretaceous coals of Lamja Formation located in Yola Sub-basin of the Northern Benue Trough, northeastern Nigeria, were analyzed based on a combined investigation of organic and inorganic geochemistry to define the paleodepositional environment condition, organic matter source inputs and their relation to paleoclimate and tectonic setting. The total organic carbon and sulfur contents of Lamja Formation coals ranges from 48.2%-67.8% wt.% and 0.42%-0.76% wt.%, respectively, pointing their deposition in freshwater environment with inferred marine influence during burial. Biomarkers and chemical compositions provide evidence for a major contribution of land-derived organic matter, with minor aquatic organic matter input. Minerals such as quartz, pyrite, kaolinite, illite, montmorillonite and calcite were present in the coals, suggesting that these minerals were sourced from terrigenous origin with slightly marine influence, considered as post-depositional. This is consistent with a significant amount of the oxides of major elements such as SiO2, Fe2O3, Al2O3, TiO2, CaO, and MgO. The investigated biomarkers are characterized by dominant odd carbon numbered n-alkanes (n-C23 to n-C33), moderately high Pr/Ph ratios (1.72-3.75), very high Tm/Ts ratios (18-29), and high concentrations of regular sterane C29, indicating oxic to relatively suboxic conditions, delta plain marine environment of deposition with prevalent contribution of land plants and minor aquatic organic matter input. Concentrations of trace elements such as Ba, Sr, Cr, Ni, V, Co and their standard ratios also suggested that the organic matter was deposited under oxic to relatively suboxic conditions, which is in parts deposited under marine influenced. Some standard binary plots of SiO2 versus (Al2O3 + K2O + Na2O) indicate a semi-arid paleoclimatic condition whereas log SiO2 versus (K2O/Na2O) also revealed passive continental margin setting. The inferred tectonic setting is in agreement with the tectonic events witnessed in the West and Central Africa during the Cretaceous period.

  4. 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)

  5. The Serenitatis Basin and the Taurus-Littrow highlands: Geological context and history

    Science.gov (United States)

    Head, James W.

    1992-01-01

    The Apollo 17 mission was targeted to land at the southeastern edge of the Serenitatis Basin, one of a number of large impact basins on the Moon. The geologic setting of the Apollo 17 site is reviewed, the implications for the formation of basins from Apollo 17 results are assessed, and unanswered questions potentially addressable with existing and new data are outlined.

  6. Neogene deformation and its implications for the structural framework of the oil fields in the Icapui-Ponta Grossa (CE) region, onshore Potiguar Basin, Brazil; Deformacao neogena e suas implicacoes na estruturacao dos campos de petroleo na regiao de Icapui-Ponta Grossa (CE), Bacia Potiguar emersa

    Energy Technology Data Exchange (ETDEWEB)

    Sousa, Debora do Carmo [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil). Programa de Pos-Graduacao em Geodinamica e Geofisica]. E-mail: debora@geologia.ufrn.br; Sa, Emanuel Ferraz Jardim de; Antunes, Alex Francisco [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil). Dept. de Geologia

    2008-06-15

    In coastal cliffs at the western portion of the Potiguar Basin (so-called Aracati Platform), the Barreiras Formation, of miocene age, displays structures pointing to high strain deformation. Detailed mapping of faults and folds geometry in the Barreiras Formation leads to recognition of extensional structures (at Ponta Grossa village) and contractional oblique structures (Vila Nova, next to Icapui town), both of them related to a trans current system bearing NE (at these locations) and NW trends (Afonso Bezerra Fault, in the central portion of the basin). These data point to a neo gene stress field which generated faults, folds and hydro plastics structures, including SL fabrics and shear zones, as well as reactivated older structures in the underlying neocretaceous sedimentary section. Reinterpretation of seismic sections from this region and other geological data at several places in the Potiguar Basin outline structures which are correlated (in style and kinematic regime) throughout the siliciclastic rocks of the Acu Formation, limestones of the Jandaira Formation and younger basalts of the Macau Formation, whose age straddles the Oligocene-Miocene boundary. This structural framework recognized at the surface has to be compatible with subsurface deformation as observed in seismic sections, which includes pulses/events of older, Neocretaceous to Paleocene age. This model has important implications as regards the structure (geometry, kinematics, age of traps) of oil reservoirs (especially the sandstones of the Acu Formation, in the Fazenda Belem Oil Field) and the processes of migration and hydrocarbon entrapment at this region of the Potiguar Basin. (author)

  7. 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.

  8. Paleomagnetism and anisotropy of magnetic susceptibility of Eocene and Miocene sediments in the Qaidam Basin, Northwest China: Implication for the Cenozoic tectonic transition and development of the northern Tibetan Plateau

    Science.gov (United States)

    Yu, X.; Guo, Z.; Huang, B.; Yin, A.; Guan, S.; Zhou, S.; Qiao, Q.; Cheng, F.; Cheng, X.; Zhang, T.

    2013-12-01

    Paleomagnetism and AMS (Anisotropy of Magnetic Susceptibility) results are reported from the middle to late Eocene Xiaganchaigou Formation and the early to middle Miocene Xiayoushashan Formation sediments at eight locations (Xichagou, Gansen, Eboliang, Heishiqiu, Luluohe, Kushuiquan, Hong Shan and Gahai), covering most outcrop regions of these two formations within the Qaidam Basin, Northwest China. These paleomagnetic data indicate that the Qaidam basin has not undergone wholesale tectonic vertical axis rotation relative to Eurasia and North China since at least middle and late Eocene. Local clockwise rotation only took place at some special locations such as Gahai. According to AMS results, 12 of 16 AMS ellipsoids belong to embryonic deformation magnetic fabric, which can be applied to reconstruct tectonic strain. Two epochs of compressive strain have been identified in the Qaidam basin during the Cenozoic: an early N-S strain no later than the Oligocene and a late NE-SW strain mainly after the early to middle Miocene. Further analysis shows that the early N-S compression in northern Qaidam basin is much more intense than that in western Qaidam basin, while the late NE-SW compression, which dominates the NW-SE-trending folds in the modern Qaidam basin, is more intense in western Qaidam basin than that in northern Qaidam basin. The stress concentration transition provides a reasonable explanation of the southeastwards migration of the deposition center in the Qaidam basin during the Cenozoic. The uniform paleomagnetic and AMS results at different localities reveal that the Qaidam basin is a relatively rigid plate, obviously different from the surrounding regions. Moreover, the appearance of E-component stress may be in close relationship with the beginning of the left-lateral Kunlun Fault or the eastwards channel flow south to the Kunlun Fault, implying that the south side of the Kunlun Fault is the active side.

  9. The Mackenzie Basin impacts study

    International Nuclear Information System (INIS)

    In 1989, a commitment was made to begin development of a framework for an integrated regional impact assessment of global warming scenarios in the Mackenzie Basin, the most populated region of Canada's north. The project, called Mackenzie Basin Impact Study (MBIS), is led by a multidisciplinary working group from government and non-governmental organizations with interests in the Basin. Objectives of MBIS include defining the direction and magnitude of regional-scale impacts of global warming scenarios on the physical, biological, and human systems of the Basin. MBIS will also identify regional sensitivities to climate, inter-system linkages, uncertainties, policy implications, and research needs. MBIS research activities as of March 1992 are outlined and policy concerns related to global warming are listed. Two new methodologies are being developed by MBIS to address particular economic and policy concerns: a socio-economic resource accounting framework and an integrated land assessment framework. Throughout MBIS, opportunities will be presented for western science and traditional native knowledge to be integrated

  10. Distribution, Statistics, and Resurfacing of Large Impact Basins on Mercury

    Science.gov (United States)

    Fassett, Caleb I.; Head, James W.; Baker, David M. H.; Chapman, Clark R.; Murchie, Scott L.; Neumann, Gregory A.; Oberst, Juergen; Prockter, Louise M.; Smith, David E.; Solomon, Sean C.; Strom, Robert G.; Xiao, Zhiyong; Zuber, Maria T.

    2012-01-01

    The distribution and geological history of large impact basins (diameter D greater than or equal to 300 km) on Mercury is important to understanding the planet's stratigraphy and surface evolution. It is also informative to compare the density of impact basins on Mercury with that of the Moon to understand similarities and differences in their impact crater and basin populations [1, 2]. A variety of impact basins were proposed on the basis of geological mapping with Mariner 10 data [e.g. 3]. This basin population can now be re-assessed and extended to the full planet, using data from the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft. Note that small-to- medium-sized peak-ring basins on Mercury are being examined separately [4, 5]; only the three largest peak-ring basins on Mercury overlap with the size range we consider here. In this study, we (1) re-examine the large basins suggested on the basis of Mariner 10 data, (2) suggest additional basins from MESSENGER's global coverage of Mercury, (3) assess the size-frequency distribution of mercurian basins on the basis of these global observations and compare it to the Moon, and (4) analyze the implications of these observations for the modification history of basins on Mercury.

  11. 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)

    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...

  12. 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.

  13. 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.

  14. 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 ...

  15. Impact of seasonal hydrological variation on the distributions of tetraether lipids along the Amazon River in the central Amazon basin: Implications for the MBT/CBT paleothermometer and the BIT index

    OpenAIRE

    ClaudiaZell; GwenaëlAbril; RodrigoSobrinho; PatriciaMoreira-Turcq

    2013-01-01

    Suspended particulate matter (SPM) was collected along the Amazonian rivers in the central Amazon basin and in three tributaries during the rising water (RW), high water (HW), falling water (FW) and low water (LW) season. Changes in the concentration and the distribution of brGDGTs, i.e. the methylation index of branched tetraethers (MBT) and the cyclization of brGDGTs (CBT), were seen in the main stem Amazon. The highest concentration of core lipid branched glycerol dialkyl glycerol tetraeth...

  16. Impact of seasonal hydrological variation on the distributions of tetraether lipids along the Amazon River in the central Amazon basin: implications for the MBT/CBT paleothermometer and the BIT index

    OpenAIRE

    Zell, Claudia; Kim, Jung-Hyun; Abril, Gwenaël; Sobrinho, Rodrigo Lima; Dorhout, Denise; Moreira-Turcq, Patricia; Sinninghe Damsté, Jaap S

    2013-01-01

    Suspended particulate matter (SPM) was collected along the Amazon River in the central Amazon basin and in three tributaries during the rising water (RW), high water (HW), falling water (FW) and low water (LW) season. Changes in the concentration and the distribution of branched glycerol dialkyl glycerol tetraethers (brGDGTs), i.e., the methylation index of branched tetraethers (MBT) and the cyclization of brGDGTs (CBT), were seen in the Amazon main stem. The highest concentration of core lip...

  17. Generation of Continental Rifts, Basins and Swells by Lithosphere Instabilities

    Science.gov (United States)

    Milelli, L.; Fourel, L.; Jaupart, C. P.

    2012-12-01

    Domal uplifts, volcanism, basin formation and rifting have often struck the same continent in different areas at the same time. Their characteristics and orientations are difficult to reconcile with mantle convection or tectonic forces and suggest a driving mechanism that is intrinsic to the continent. The rifts seem to develop preferentially at high angles to the edge of the continent whereas swells and basins seem confined to the interior. Another intriguing geometrical feature is that the rifts often branch out in complicated patterns at their landward end. In Western Africa, for example, magmatic activity currently occurs in a number of uplifted areas including the peculiar Cameroon Volcanic Line that stretches away from the continental margin over about 1000 km. Magmatic and volcanic activity has been sustained along this line for 70 My with no age progression. The mantle upwelling that feeds the volcanoes is not affected by absolute plate motions and hence is attached to the continent. The Cameroon Volcanic Line extends to the Biu swell to the North and the Jos plateau to the West defining a striking Y-shaped pattern. This structure segues into several volcanic domes including the Air, the Hoggar, the Darfur, the Tibesti and the Haruj domes towards the Mediterranean coast. Another example is provided by North America, where the late Proterozoic-early Ordovician saw the formation of four major basins, the Michigan, Illinois, Williston and Hudson Bay, as well as of major rifts in southern Oklahoma and the Mississipi Valley within a short time interval. At the same time, a series of uplifts developed, such as the Ozark and Nashville domes. Motivated by these observations, we have sought an explanation in the continental lithosphere itself. We describe a new type of convective instability at the base of the lithosphere that leads to a remarkable spatial pattern at the scale of an entire continent. We carried out fluid mechanics laboratory experiments on buoyant blocks of finite size that became unstable due to cooling from above and describe the peculiar horizontal planform that developed. Dynamical behaviour depends on three dimensionless numbers, a Rayleigh number for the unstable block, a buoyancy number that scales the intrinsic density contrast to the thermal one and the aspect ratio of the block. Within the block, instability develops in two different ways in an outer annulus and in an inner region. In the outer annulus, upwellings and downwellings take the form of radial rolls spaced regularly. In the interior region, the planform adopts the more familiar form of polygonal cells. Translated to geological conditions, such instabilities should manifest themselves as linear rifts striking at a right angle to the continent-ocean boundary and an array of domal uplifts, volcanic swells and basins in the continental interior. The laboratory data lead to simple scaling laws for the dimensions and spacings of the convective structures. For the sub-continental lithospheric mantle, these dimensions and distances take values in the 500-1000 km range, close to geological examples. The large intrinsic buoyancy of Archean lithospheric roots prevents this type of instability, which explains why the widespread volcanic activity that currently affects Western Africa is confined to post-Archean domains.

  18. 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.

  19. 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.

  20. Geysers: Lower Geyser Basin

    Science.gov (United States)

    Yellowstone National Park

    This Yellowstone National Park web site is dedicated to Lower Geyser Basin. It includes images and descriptions of Queen's Laundry and Sentinel Meadows, Sentinel Cone, Ojo Caliente, Pocket Basin Mud Pots, Imperial Geyser, Spray Geyser, Octopus Spring, Great Fountain Geyser, White Dome Geyser, Pink Cone Geyser, Bead Geyser, Narcissus Geyser, Steady Geyser, Silex Spring, Fountain Paint Pot, Fountain Geyser, Clepsydra Geyser, and Jelly Geyser.

  1. 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

  2. Detours around basin stability in power networks

    Science.gov (United States)

    Schultz, Paul; Heitzig, Jobst; Kurths, Jürgen

    2014-12-01

    To analyse the relationship between stability against large perturbations and topological properties of a power transmission grid, we employ a statistical analysis of a large ensemble of synthetic power grids, looking for significant statistical relationships between the single-node basin stability measure and classical as well as tailormade weighted network characteristics. This method enables us to predict poor values of single-node basin stability for a large extent of the nodes, offering a node-wise stability estimation at low computational cost. Further, we analyse the particular function of certain network motifs to promote or degrade the stability of the system. Here we uncover the impact of so-called detour motifs on the appearance of nodes with a poor stability score and discuss the implications for power grid design.

  3. 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.

  4. 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.

  5. Emplacement of magma in sedimentary basins

    Science.gov (United States)

    Malthe-Sorenssen, A.; Planke, S.

    2002-12-01

    Sheet-like intrusive complexes are commonly present in sedimentary basins on rifted volcanic margins. Such sill complexes have important impact on petroleum maturation, migration and trapping. We are currently completing an integrated seismic, field and theoretical study on the petroleum implications of sill intrusions. One aspect of this study has been to get new understanding of the magma emplacement processes based on integrated numerical modeling and geophysical/geological mapping activities. Extensive sill complexes have been identified and mapped in the NE Atlantic and Karoo basins based on seismic, borehole, remote sensing and field data. Early Tertiary intrusive complexes are present in the Voring and More basins offshore mid-Norway. Similar sill complexes are exposed onshore in Cretaceous to Permian age sedimentary sequences on the conjugate central-east Greenland margin. A voluminous Jurassic age intrusive complex is well exposed in the Permian to Jurassic Karoo basin as the erosionally strong dolerites form an impressive mountainous landscape in large parts of South Africa. The sheet intrusions are found at paleodepths of 0-6 km. Deep intrusions are generally long and smooth, whereas shallow intrusions are rough, transgressive and commonly saucer-shaped. Saucer-shaped intrusions are present in unstructured basin segments. The diameter of the saucers increases with depth. Structured basin segments are characterized by a variety of sill complex geometries. The intrusions generally mimic the basin structure. In nature, magma is emplaced in internally pressurized, planar cracks. The emplacement process is controlled by the local stress field and complex interactions of buoyancy forces, host rock resistance to fracture, elastic deformation of country rock, magma hydrostatic pressure and fluctuating magma pressure, magma viscosity and weight of overburden. We have developed a discrete element model to study the emplacement process. Results from the modeling and geological/geophysical mapping show that sill emplacement is a dynamic process where both 1) stress field anisotropy generated by the emplacement process and 2) local structural heterogeneities have important influence on the final geometry of the sill complex. Saucer-shaped sill complexes are formed spontaneously by the numerical model in a simple, stratified basin. Asymmetric stress field is developed around the tip of the sill during the emplacement, causing the melt to transgress and forming the inclined sheets. The modeling and field data show that faults and weak intra-sedimentary horizons are preferentially used during the emplacement process. Inflation and deflation cycles are particularly common in the vicinity of major structural heterogeneities.

  6. Fractures as Preferential Flowpaths for Aquifer Storage and Recovery (ASR Injections and Withdrawals: Implications for Environmentally Sensitive Near-Shore Waters, Wetlands of the Greater Everglades Basin and the Regional Karst Floridan Aquifer System

    Directory of Open Access Journals (Sweden)

    Sydney T. Bacchus

    2015-05-01

    Full Text Available In theory, “aquifer storage and recovery” (ASR is a form of artificial aquifer recharge consisting of threecomponents: (1 aquifer injections of fluids; (2 withdrawals of the injected fluids; and (3 a period of timebetween the injections and withdrawals that is considered to be aquifer “storage” of the injected fluids. Theinjected fluids may be: (1 treated sewage effluent (also known as reclaimed, reuse, or bright water; (2stormwater runoff pumped out of canals, mine pits or other areas; (3 surface waters from natural lakes andstreams; or (4 ground water from different aquifer zones. An evaluation of existing data from more than 80injection/withdrawal cycle tests at 18 ASR sites in 9 counties throughout southern Florida, in the regional karstFloridan aquifer system of the United States (US revealed that less than 25% actual “recovery” was achievedfrom ASR wells where water from various sources was injected into the regional karst aquifer system.Determination of actual “recovery” was based on the reported chloride content of injected and recovered waterand was more suggestive of fluid disposal than aquifer “recharge.” Actual “recovery” for those ASR tests,adjusted to the chloride concentrations of injected fluids, ranged from 0-17% for “storage” periods that rangedfrom 0-181 days. Although results of actual “recovery” provide little support for the concept of “stored” water, inreality those results also over-estimate the volume of injected water that is stored because it assumes that waterrecovered at the same chloride concentration is the same water that was injected. There is no evidence in theASR data to support that assumption. The low actual “recovery” rates occurred despite the fact that 28 of thecycle tests had a “storage” period < 1 day and the longest “storage” period tested did not exceed 181 days. Thosebrief “storage” periods also were insufficient to meet the stated agency objectives of retrieving the injected fluidsduring the dry season, more than six months after injection of what is termed “excess water” during the rainyseason. Despite those results, the agency’s Final Technical Data Report (TDR and groundwater model releasedin 2014 concluded that: (1 “recovery” from those wells would range from 70-100% and (2 232 ASR wells (94in the upper Floridan aquifer, 37 in the Avon Park Permeable Zone of the middle Florida aquifer and 101 in theBoulder Zone could be completed in Florida’s Greater Everglades Basin (basin as restoration. That Final TDRdid not consider differences in chloride content between water that was injected into and withdrawn from theASR cycle tests and that groundwater model for the basin did not include the anisotropy option or preferentialflow through karst conduits such as fractures. Preferential flow of water injected and withdrawn could result inboth low ASR “recovery” rates and environmental harm, such as submarine groundwater discharge (SGDcontaminated with pollutants, including nutrients that result in harmful algal blooms (HABs. That TDR andgroundwater model for southern Florida also did not evaluate the direct, indirect or cumulative adverse impactsof preferential flow from ASR injections and withdrawals (e.g., through fractures on federally threatened andendangered species, environmentally sensitive areas or on sinkhole formation. Our evaluation of the basinvicinity also included analyses of fracture frequency, length and proximity to ASR wells, other injection andwithdrawal wells and modern sinkholes, based on georeferenced and transformed lineaments from threeindependent sources: the US Army Corps of Engineers (ACOE, 2004c, Florida Department of Transportation(FDOT, 1973, and Vernon (1951. Based on the three lineament data sets included in our study, includingwww.ccsenet.org/jgg Journal of Geography and Geology Vol. 7, No. 2; 2015118fractures that extend for considerable distances through environmentally sensitive areas in the basin such as theBig Cypress National Preserve, Biscayne National P

  7. Impact of seasonal hydrological variation on the distributions of tetraether lipids along the Amazon River in the central Amazon basin: implications for the MBT/CBT paleothermometer and the BIT index.

    Science.gov (United States)

    Zell, Claudia; Kim, Jung-Hyun; Abril, Gwenaël; Sobrinho, Rodrigo Lima; Dorhout, Denise; Moreira-Turcq, Patricia; Sinninghe Damsté, Jaap S

    2013-01-01

    Suspended particulate matter (SPM) was collected along the Amazon River in the central Amazon basin and in three tributaries during the rising water (RW), high water (HW), falling water (FW) and low water (LW) season. Changes in the concentration and the distribution of branched glycerol dialkyl glycerol tetraethers (brGDGTs), i.e., the methylation index of branched tetraethers (MBT) and the cyclization of brGDGTs (CBT), were seen in the Amazon main stem. The highest concentration of core lipid (CL) brGDGTs normalized to particulate organic carbon (POC) was found during the HW season. During the HW season the MBT and CBT in the Amazon main stem was also most similar to that of lowland Amazon (terra firme) soils, indicating that the highest input of soil-derived brGDGTs occurred due to increased water runoff. During the other seasons the MBT and CBT indicated an increased influence of in situ production of brGDGTs even though soils remained the main source of brGDGTs. Our results reveal that the influence of seasonal variation is relatively small, but can be clearly detected. Crenarchaeol was mostly produced in the river. Its concentration was lower during the HW season compared to that of the other seasons. Hence, our study shows the complexity of processes that influence the GDGT distribution during the transport from land to ocean. It emphasizes the importance of a detailed study of a river basin to interpret the MBT/CBT and BIT records for paleo reconstructions in adjacent marine setting. PMID:23966986

  8. Integrated geophysical investigations of linkages between Precambrian basement and sedimentary structures in the Ucayali basin, Peru; Fort Worth basin, Texas; and Osage County, Oklahoma

    Science.gov (United States)

    Elebiju, Olubunmi Olumide

    I conducted integrated geophysical studies within the Fort Worth basin, Texas; Osage County, Oklahoma, and the Ucayali basin, Peru. My studies are directed at understanding the relationships or links between Precambrian basement structures and sedimentary structures using these three areas as case studies. Links between basement structure, hydrocarbon reservoirs, and sedimentary sequences are not a new concept. Such relationships have been documented in the Paradox, Hardeman, Anadarko, Arkoma, Ardmore and Williston basins among others. Structures such as fault zones that can influence the formation of sedimentary basins and mineral deposits are often formed by intraplate tectonism. In order to compare the relationship between the Precambrian basement structures and sedimentary structures, I analyzed series of derivative and filtered maps of aeromagnetic and gravity data, which enhance basement structures, that were integrated with seismic data and seismic attribute data that enhance structures within the sedimentary sections. Other information such as well data and geologic information etc were also integrated. This integrated workflow facilitates the comparison of the links or relationships between the two structures. The results of the Fort Worth basin are presented in Chapter 3. The results of this integrated study show that the sedimentary structures within the study area are mainly related to basement structures because these structures are aligned parallel to anomalies identified on the high-resolution aeromagnetic (HRAM) data. The northeast-southwest and northwest-southeast orientations of sedimentary features are consistently parallel with Precambrian structural fabrics that are associated with structures such as the northeast trending Ouachita orogenic belt and the northwest trending Muenster Arch, which reactivated a late Cambrian/Late Precambrian faults. The knowledge gained in this study will impact oil and gas exploration and development within the study area because, the orientation of the natural and induced fractures can be predicted even if seismic data is limited or unavailable. In Chapter 4, the results of an integrated analysis that includes the use of 3D seismic data, seismic attributes, and derivative maps from potential field data to study the basement, Mississippi Chert and the Arbuckle Group of Osage County, Oklahoma are presented. The workflow employed in this study was effective in studying and identifying polygonal, highly coherent, and high amplitude lineaments that strike northwesterly and northeasterly within these reservoirs. Basement structure lineaments are found to be parallel in orientation with the trend of lineaments seen within the Mississippian Chert and the Arbuckle Group. The northwest-striking lineaments may be related to the late-Paleozoic tectonism that affected both the Precambrian and Paleozoic section of Osage County. Another part of this research investigated the large gravity and magnetic anomalies and their association with the Mid-Continent Rift System (MCRS). Results of this analysis revealed prominent northeast trending anomalies that suggest that the MCRS extends into northern Oklahoma. However, geochronological data for basement rocks suggest that this extension would have to be limited to intrusive bodies that have little or no subcrops. The integrated study conducted in the Ucayali basin of Peru revealed that the northwest-southeast trending lineaments interpreted as Precambrian basement structures are sub-parallel to the late Paleozoic fold and thrust belts that resulted from the shortening associated with the formation of the Andes. These fold and thrust belts are reactivated along the zones of weaknesses that already existed in the Precambrian basement. The east-northeast lineaments are located beneath the Fitzcarrald Arch locate above the buoyant Nazca ridge. I interpret these east-northeast lineaments as part of the Ene Pisco -- Abancay Fitzcarrald tectonic lineaments, which is one of the five tectonic domains in these region. Gravity modeling suggests that t

  9. 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.

  10. Tharsis Basin Aquifer System

    Science.gov (United States)

    University of Arizona

    This is a QuickTime movie animating an enormous ancient drainage basin and aquifer system in the Tharsis region of Mars. The movie shows the geological stages of the aquifer system, as reported in a University of Arizona study.

  11. Aquifer - Basin and range

    Science.gov (United States)

    Aquifer basics outlining the makeup of the basin and range aquifers. Description and maps of unconsolidated sand and gravel aquifers. This site consists of information for the Southwestern portion of the United States, consisted of Arizona, California, Nevada, and Utah.

  12. 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.

  13. 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

  14. 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

  15. K Basins Hazard Analysis

    Energy Technology Data Exchange (ETDEWEB)

    WEBB, R.H.

    1999-12-29

    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.

  16. 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.

  17. 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.

  18. 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.

  19. The Cretaceous Gyeongsang Basin

    Energy Technology Data Exchange (ETDEWEB)

    Son, Jin-Dam; Kwak, Young-Hoon; Bong, Pil-Yoon [Korea Institute of Geology Mining and Materials, Taejon (KR)] (and others)

    1999-12-01

    Since 1992 sedimentary basin analysis to assess petroleum potential of the Cretaceous and Tertiary strata in the Korean onshore and continental shelf have been carried out. The Cretaceous non-marine strata mainly occupy the Gyeongsang Basin in southeastern part of the Korean Peninsula and small basins such as Haenam and Gyeokpo depressions in western coastal areas. The Tertiary strata are mostly distributed in Domi, Cheju, Socotra subbasins, and Okinawa Trough in the South Continental Shelf, and Kunsan and Heuksan basins in the West. The basin evolution and petroleum potential for each basins are characterized as follow. The Cretaceous Gyeongsang sediments were deposited in three subbasins including Milyang, Euisung and Yongyang subbasins. Based on the volcaniclastic sediment distribution, the Gyeongsang Supergroup can be subdivided into Sindong, Hayang and Yucheon Groups. The Sindong Group was deposited in alluvial fan, flood plain and lacustrine margin environments: the Hayang Group was formed in flood plain, alluvial fan, braided stream and shallow lacustrine environments. The black shales in Nakdong and Jinju formations are interpreted to contain abundant organic matter during the deposition, thermal maturity reaching up to the zone of dry gas formation. Because porosity and permeability are too low, the sandstones can act as a tight gas reservoir rather than conventional oil and gas reservoir. (author). 6 tabs., 9 figs.

  20. A Large Basin on the Near Side of the Moon

    Science.gov (United States)

    Byrne, Charles Joseph

    2007-12-01

    The differences between the surface structure of the near side and the far side of the Moon have been topics of interest ever since photographs of the far side have been available. One recurrent hypothesis is that a large impact on the near side has deposited ejecta on the far side, resulting in thicker crust there. Specific proposals were made by P.H. Cadogan for the Gargantuan Basin and by E.A. Whitaker for the Procellarum Basin. Despite considerable effort, no consensus has been reached on the existence of these basins. The problem of searching for such a basin is one of finding its signature in a somewhat chaotic field of basin and crater impacts. The search requires a model of the topographic shape of an impact basin and its ejecta field. Such a model is described, based on elevation data of lunar basins collected by the Lidar instrument of the Clementine mission and crustal thickness data derived from tracking Clementine and other spacecraft. The parameters of the model are scaled according to the principles of dimensional analysis and isostatic compensation in the early Moon. The orbital dynamics of the ejecta and the curvature of the Moon are also taken into account. Using such a scaled model, a search for the best fit for a large basin led to identification of a basin whose cavity covers more than half the Moon, including the area of all of the impact basins visible on the near side. The center of this basin is at 22 degrees east longitude and 8.5 degrees north latitude and its average radius is approximately 3,160 km. It is a megabasin, a basin that contains other basins (the far side South Pole-Aitken Basin also qualifies for that designation). It has been called the Near Side Megabasin. Much of the material ejected from the basin escaped the Moon, but the remainder formed an ejecta blanket that covered all of the far side beyond the basin rim to a depth of from 6 to 30 km. Isostatic compensation reduced the depth relative to the mean surface to a range of 1 5 km, but the crustal thickness data reveals the full extent of the original ejecta. The elevation profile of the ejecta deposited on the far side, together with modification for subsequent impacts by known basins (especially the far side South Pole-Aitken Basin) matches the available topographic data to a high degree. The standard deviation of the residual elevations (after subtracting the model from the measured elevations) is about one-half of the standard deviation of the measured elevations. A section on implications discusses the relations of this giant basin to known variations in the composition, mineralogy, and elevations of different lunar terranes.

  1. 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

  2. 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

  3. Putting the "Basin" Back in Southeastern Arizona's Basin and Range

    Science.gov (United States)

    Jungers, M. C.; Heimsath, A. M.

    2011-12-01

    The pace and pattern of southeastern Arizona's transition from a series of internally drained sedimentary basins to the modern, integrated Gila River system are poorly constrained. Steep normal faulting associated with the Basin and Range disturbance ~12-5 Ma created structural basins that filled with sediment throughout the Late Miocene and Early Pliocene. Early rates of basin deposition were rapid due to high upland erosion rates driven by continuous base level fall within the extensional basins. Subsequently, as tectonic forcing waned, sedimentation rates slowed until a combination of basin spillover events and headward capture integrated individual basins into a through-flowing drainage network. Newly integrated streams with suddenly lower base levels rapidly incised, perching the uppermost surfaces of basin fill and eroding large volumes of sediment throughout the Quaternary. Relatively thin (10-100 m), coarse-grained alluvial fan remnants on erosional surfaces of basin fill or bedrock pediments are commonly the highest elevation, undeformed deposits in basins of southeastern Arizona. Although they often overlie basin-bounding faults, it is rare that they are cut by these faults. This suggests quiescent tectonics both during and after the deposition of these alluvial fans. Early work on two complexes of these alluvial fan remnants (Menges and McFadden, 1981) used the degree of soil development of relict soils on the fan surfaces to estimate an age of at least 1 Ma for these basin high stands. Further, the degree of soil oxidation and the depth of weathering suggest a wetter climate when these relict soils were forming. This age estimate and inference of a different climate begin to inform a model for climatically driven deposition of these coarse-grained fan deposits at the Pliocene-Pleistocene shift, but absolute dates are lacking. Here we report spatial and temporal patterns of regional drainage integration focusing on the timing of abandonment for uppermost surfaces of basin fill (10Be derived surface exposure dates are pending) and we present basin surface reconstructions. Previous research has suggested that uppermost basin fill surfaces are roughly correlative. We use our data to 1) test the hypothesis of broadly synchronous timing for a regional shift from internal drainage to external drainage for southeastern Arizona's basins, and 2) infer incision rates through the Quaternary. We have identified basin high stand remnants throughout several basins of interest in southeastern Arizona, and use spline interpolations to reconstruct basin fill surfaces. By subtracting the modern day topography from reconstructed basin surfaces, we quantify first order estimates of incision rates through basin fill since drainage integration. Our surface exposure dates will allow accurate quantification of incision rates for each basin, and resolve regional patterns of drainage integration.

  4. K Basin Hazard Analysis

    International Nuclear Information System (INIS)

    The K East (KE)/K West (KW) Basins in the 100 K Area of the Hanford Site have been used for storage of irradiated N Reactor and single-pass reactor fuel. Remaining spent fuel is continuing to be stored underwater in racks and canisters in the basins while fuel retrieval activities proceed to remove the fuel from the basins. The Spent Nuclear Fuel (SNF) Project is adding equipment to the facility in preparation for removing the fuel and sludge from the basins In preparing this hazard analysis, a variety of hazard analysis techniques were used by the K Basins hazard analysis team, including hazard and operability studies, preliminary hazard analyses, and ''what if'' analyses (WHC-SD-SNF-PHA-001, HNF-2032, HNF-2456, and HNF-SD-SNF-SAD-002). This document summarizes the hazard analyses performed as part of the safety evaluations for the various modification projects and combines them with the original hazard analyses to create a living hazard analysis document. As additional operational activities and modifications are developed, this document will be updated as needed to ensure it covers all the hazards at the K Basins in a summary form and to ensure the subsequent safety analysis is bounding. This hazard analysis also identifies the preliminary set of design features and controls that the facility could rely on to prevent or reduce the frequency or mitigate consequences of identified accident conditions based on their importance and significance to safety. The operation and significance to safety. The operational controls and institutional programs relied on for prevention or mitigation of an uncontrolled release are identified as potential technical safety requirements. All operational activities and energy sources at the K Basins are evaluated in this hazard analysis. Using a systematic approach, this document identifies hazards created by abnormal operating conditions and external events (e.g., earthquakes) that have the potential for causing undesirable consequences to the facility worker, the onsite individual, or the public. 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 complies with the requirements of 10 CFR 830

  5. Stable-isotope (H, O, and Si) evidence for seasonal variations in hydrology and Si cycling from modern waters in the Nile Basin: implications for interpreting the Quaternary record

    Science.gov (United States)

    Cockerton, H. E.; Street-Perrott, F. A.; Leng, M. J.; Barker, P. A.; Horstwood, M. S. A.; Pashley, V.

    2013-04-01

    Seasonal variations in hydrology and Si cycling in the Nile Basin were investigated using stable-isotope (H, O, and Si) compositions and dissolved Si (DSi) concentrations of surface waters, as a basis for interpreting lacustrine diatom sequences. ?18O ranged from -4.7 to +8.0‰ in the wet season and +0.6 to +8.8‰ in the dry season (through 2009-2011). Higher ?18O values during the dry season reflected increased evapotranspiration and open water evaporation under conditions of lower humidity. Progressive downstream enrichment in the heavy isotope 18O also occurred in response to cumulative evaporative losses from open water bodies and swamps. ?30Si values of DSi ranged from +0.48 to +3.45‰ during the wet season and +1.54 to +4.66‰ during the dry season, increasing the previously reported global upper limit for ?30Si values in natural waters by 1‰. Si-isotope fractionation was most intense during the dry season when demand for DSi by aquatic ecosystems exceeded supply. Progressive downstream enrichment in the heavy isotope 30Si, coupled with decreasing DSi concentrations, represented cumulative Si uptake by diatoms, macrophytes and other Si-accumulating aquatic organisms. The pronounced seasonal variations in DSi concentrations and Si-isotope compositions in the River Nile suggest that its DSi flux to the ocean may have varied significantly on a glacial/interglacial time scale, with important consequences for the marine Si budget and consequently the global C cycle. Anthropogenic impacts were evident in both the water- and Si-isotope datasets, especially during the dry season and along the Main Nile, where water management is most intensive.

  6. Origin of Mesozoic and Tertiary granite in the Western United States and implications for Pre-Mesozoic crustal structure 1. Nd and Sr isotopic studies in the geocline of the Northern Great Basin

    International Nuclear Information System (INIS)

    Mesozoic and Tertiary granite rocks in and adjacent to the northern Great Basin (NGB) in Nevada and Utah display a wide range of initial 143Nd/144Nd (epsilon/sub Nd/) and 87Sr/86Sr (epsilon/sub Sr/) values which vary regularly with geographic position. From the Klamath Mountains inland 500 km to central Nevada, granite epsilon/sub Nd/ values decrease regularly from +8 to -6 and correlate with epsilon/sub Sr/ values that increase from -20 to +60. In east-central Nevada, near the trace of the Roberts Mountains Thrust (RMT), the epsilon/sub Nd/ values decrease from -6 to an average of -18, while epsilon/sub Sr/ becomes highly variable with values generally greater than +100. These isotopic discontinuities correspond to the west-to-east facies transition from pelagic clastic sedimentary rocks to shelf carbonates and to the shift in the dominant granite bulk composition from metaluminous to peraluminous. In the eastermost NGB a second discontinuity in epsilon/sub Sr/ occurs with values dropping to approx.+60; average epsilon/sub Nd/ remains at -18. Combined with known aspects of NGB geology the isotopic data suggest that west of the RMT, granites formed via interaction of magma derived from a LREE-depleted pelagic sedimentary rock. Variations in 87Rb/86Sr with Sr, and 147Sm/144Nd with epsilon/sub Nd/, indicate that crystal fractionation accompanied assimilation, but that plagioclase wasied assimilation, but that plagioclase was not an important fractioning phase. East of the RMT, granites appear to be primarily derived fom precambrian continental basement with little mantle input. The isotopic discontinuities near the RMT mark the western edge of precambrian basement and occur 100-200 km east of the 87Sr/86Sr ( = 0.7060) line of Kistleer and Peterman [1973

  7. WiBasin: basin management through an integrated platform

    OpenAIRE

    Llort Pavon, Xavier; Sánchez-Diezma Guijarro, Rafael; de Sancho, David; Rodríguez, Álvaro; Berenguer Ferrer, Marc; Sempere Torres, Daniel

    2014-01-01

    In this work we present WiBasin, a cloud platform for basin and dam management. It includes different sources of precipitation (both observed and forecasted), integration over the catchment domain (to provide an aggregated value of potential rainfall accumulated over the basin) , and a complete dissemination environment (web-viewer, capability of issuing hazard warnings with configurable thresholds, SMS, mails, etc.)

  8. The Chelyabinsk coal basin

    Energy Technology Data Exchange (ETDEWEB)

    Ryleev, V.S.; Kornilkov, V.N. (Proizvodstvennoe Obedinenie Chelyabinskugol' (Russian Federation))

    1993-05-01

    Discusses coal mining in the Chelyabinsk coal basin in the Urals. The following aspects are evaluated: position of the Chelyabinsk basin, its coal reserves, properties of brown coal (calorific value of run-of-mine coal ranges from 4,000 to 4,500 kcal, carbon content from 72% to 74%), coal seam thickness, depth, coal seams prone to spontaneous combustion, underground coal mining (10 mines constructed from 1933 to 1969), schemes for coal deposit development and mining (schemes without leaving coal support pillars), coal losses, thin seam mining, problems associated with strata control, prevention of endogenous fires, equipment for underground coal mining. Selected aspects of surface coal mining in 3 surface mines of the Chelyabinsk basin are also discusssed: coal output, mining conditions, economic aspects of surface coal mining.

  9. 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 downsincreases 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.

  10. 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.

  11. 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.

  12. The lunar Procellarum basin

    Science.gov (United States)

    Whitaker, E. A.

    It is still widely assumed that the Imbrium basin is the largest such structure on the lunar nearside, even though it has been pointed out that geochemical and other data from the Apollo missions strongly indicate that the Imbrium impact occurred eccentrically within the confines of a pre-existing, much larger (the 'Gargantuan') basin. There does, in fact, also exist supporting topographical evidence for the reality of this basin, although the centroid of high radioactivity lies a little west of the topographical center. This topographical evidence consists of incomplete arcs of three closely concentric circles marked by mare shorelines, major systems of mare ridges, and some minor scarps. The rings have surface diameters of 1700, 2400 and 3200 km, and are centered at about 23 deg N, 15 deg W, near the crater Timocharis. Any discussions of the distribution of surface minerals, the compositions, ages, histories and petrology of lunar rocks, etc. should recognize and include any possible effects resulting from the formation of this basin.

  13. 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

  14. 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.)

  15. The National Basin Delineation Project.

    Science.gov (United States)

    Arthur, Ami T.; Cox, Gina M.; Kuhnert, Nathan R.; Slayter, David L.; Howard, Kenneth W.

    2005-10-01

    The National Basin Delineation Project (NBDP) was undertaken by the National Severe Storms Laboratory to define flash-flood-scale basin boundaries for the country in support of the National Weather Service (NWS) Flash Flood Monitoring and Prediction (FFMP) system. FFMP-averaged basin rainfall calculations allow NWS forecasters to monitor precipitation in flash-flood-scale basins, improving their ability to make accurate and timely flash-flood-warning decisions. The NBDP was accomplished through a partnership with the U.S. Geological Survey Earth Resources Observation Systems (EROS) Data Center (EDC). The one-arc-second (approximately 30 m)-resolution digital terrain data in the EDC's National Elevation Dataset provided the basis for derivation of the following digital maps using a geographic information system: 1) a grid of hydrologically conditioned elevation values (all grid cells have a definned flow direction), 2) a grid of flow direction indicating which of eight directions water will travel based on slope, 3) a grid of flow accumulation containing a count of the number of upstream grid cells contributing flow to each grid cell, 4) synthetic streamlines derived from the flow accumulation grid, and 5) flash-flood-scale basin boundaries. Special techniques were applied in coastal areas and closed basins (basins with no outflow) to ensure the accuracy of derived basins and streams. Codifying each basin with a unique identifier and including hydrologic connectivity information produced a versatile, seamless dataset for use in FFMP and other national applications.

  16. 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)

  17. Exploration for oil and gas in the sedimentary basins

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, M.N.V.

    1983-02-01

    Sedimentary basins, Pranhita-Godavari Graben, Krishna-Godavari Basin, Palar Basin, Cauvery Basin, and Kerala Basin in India are described as to dimensions, geological formation, and potential as hydrocarbon reserves. (BLM)

  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. 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.

  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. 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

  2. Helminth parasites of freshwater fishes, Nazas River basin, northern Mexico

    Directory of Open Access Journals (Sweden)

    León, G. Pérez-Ponce

    2010-01-01

    Full Text Available This paper represents the first study of the helminth parasites of freshwater fishes from the Nazas River basinin northern Mexico. Between July 2005 and December 2008, 906 individual fish were collected and examined for helminthparasites in 23 localities along the river basin. Twenty-three species of fish were examined as a part of this inventory work.In total, 41 helminth species were identified: 19 monogeneans, 10 digeneans, seven cestodes, one acanthocephalan, andfour nematodes. The biogeographical implications of our findings are briefly discussed.

  3. Lunar and Planetary Science XXXV: Lunar Crust as Sampled by Basins and Craters

    Science.gov (United States)

    2004-01-01

    The session "Lunar Crust as Samples by Basins and Craters" included:Radar Properties of Lunar Basin Deposits; Numerical Modeling of the South Pole-Aitkin Impact; Lunar South Pole-Aitken Impact Basin: Topography and Mineralogy; Comparison of the Geologic Setting of the South Pole-Aitken Basin Interior with Apollo 16: Implications for Regolith Components; Identifying Impact Events Within the Lunar Cataclysm from 40Ar-39Ar Ages of Apollo 16 Impact Melt Rocks; Apollo 16 Mafic Glass: Geochemistry, Provenance, and Implications; Lunar Meteorite PCA 02 007: A Feldspathic Regolith Breccia with Mixed Mare/Highland Components; Compositional Constraints on the Launch Pairing of LAP 02205 and PCA 02007 with Other Lunar Meteorites; An In-Situ Study of REE Abundances in Three Anorthositic Impact Melt Lunar Highland Meteorites; A Crustal Rock Clast in Magnesian Anorthositic Breccia, Dhofar 489 and Its Excavation from a Large Basin; The Origin and Impact History of Lunar Meteorite Yamato 86032; Evolved Lithologies and Their Inferred Sources in the Northwestern Procellarum Region of the Moon; and Revisiting the Interpretation of Thorium Abundances at Hansteen Alpha.

  4. Sustaining Exploration in Mature Basins

    International Nuclear Information System (INIS)

    Exploration is a business like any other business driven by opportunity, resources and expectation of profit. Therefore, exploration will thrive anywhere the opportunities are significant, the resources are available and the outlook for profit (or value creation) is good. To sustain exploration activities anywhere, irrespective of the environment, there must be good understanding of the drivers of these key investment criteria. This paper will examine these investment criteria as they relate to exploration business and address the peculiarity of exploration in mature basin. Mature basins are unique environment that lends themselves a mix of fears, paradigms and realities, particularly with respect to the perception of value. To sustain exploration activities in a mature basin, we need to understand these perceptions relative to the true drivers of profitability. Exploration in the mature basins can be as profitable as exploration in emerging basins if the dynamics of value definition-strategic and fiscal values are understood by operators, regulators and co ventures alike. Some suggestions are made in this presentation on what needs to be done in addressing these dynamic investment parameters and sustaining exploration activities in mature basins

  5. 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.

  6. Iron in the Japan Sea and its implications for the physical processes in deep water

    Science.gov (United States)

    Takata, Hyoe; Kuma, Kenshi; Isoda, Yutaka; Otosaka, Shigeyoshi; Senjyu, Tomoharu; Minagawa, Masayuki

    2008-01-01

    Labile dissolved Fe (DFe, <0.22 ?m fraction) and total dissolvable Fe (TDFe, unfiltered) were examined throughout the water column of the northeastern (Japan Basin) and mid-eastern (Yamato Basin) basin regions in the Japan Sea. We observed extremely high vertically integrated TDFe inventories and low nutrient concentrations at the surface water in both basins, probably resulting from high atmospheric Fe input to nutrient-depleted surface water. DFe in both basins was characterized by mid-depth maxima and, below that, a slight decrease with depth in deep water and uniform concentration in bottom water. In the Japan Basin, surprisingly, TDFe concentrations in bottom water were lower than those in deep water, resulting from the injection of new bottom water. On the contrary, TDFe concentrations in bottom water of the Yamato Basin increased gradually with depth and were higher than those in deep water probably due to the supply of iron during the horizontal transport of the bottom water in the Japan Basin towards the Yamato Basin. The TDFe with a high percentage of labile particulate Fe (TDFe minus DFe) may have important implications for understanding the physical processes of bottom water in the Japan Sea.

  7. Characterization of production commingled from deep basin plays, Wild River region of western Alberta

    Energy Technology Data Exchange (ETDEWEB)

    Dixon, R.K.; Flint, D.W. [Forward Energy Group, Calgary, AB (Canada)

    2010-07-01

    More exploration and development investment focus is being directed towards unconventional gas resources as a result of the productivity decline in conventional North American gas reservoirs. The most productive of the unconventional group are tight gas plays. Within the Western Canada Sedimentary Basin (WCSB), the Deep Basin play is the most dominant and the largest source for unconventional gas. Commingling is particularly common in the Wild River region of the Deep Basin area, where up to 8 potential plays may be stacked for completion. This paper discussed the characteristics and distribution of commingled wells in the Wild River region. It also discussed the implications for resource estimates and development in other areas of the Deep Basin, based on the results observed in the Wild River region. Specific issues that were addressed included the impact of these multi-play wells in terms of activity; the location of the commingled play wells; and the plays that are completed most frequently in these commingled wells. This paper also discussed whether recovery per well is improving with experience and whether recovery improved as more plays are completed. Other topics that were discussed included the overall success rate in this area; the density per section of Deep Basin producing wells; and how strategies and results vary by operator. It was concluded that most multiplay wells are drilled to evaluate all 8 Deep Basin intervals, and most are commonly completed in 3 or more plays. 4 refs., 15 figs.

  8. Fuel storage basin seismic analysis

    International Nuclear Information System (INIS)

    The 105-KE and 105-KW Fuel Storage Basins were constructed more than 35 years ago as repositories for irradiated fuel from the K East and K West Reactors. Currently, the basins contain irradiated fuel from the N Reactor. To continue to use the basins as desired, seismic adequacy in accordance with current US Department of Energy facility requirements must be demonstrated. The 105-KE and 105-KW Basins are reinforced concrete, belowground reservoirs with a 16-ft water depth. The entire water retention boundary, which currently includes a portion of the adjacent reactor buildings, must be qualified for the Hanford Site design basis earthquake. The reactor building interface joints are sealed against leakage with rubber water stops. Demonstration of the seismic adequacy of these interface joints was initially identified as a key issue in the seismic qualification effort. The issue of water leakage through seismicly induced cracks was also investigated. This issue, coupled with the relatively complex geometry of the basins, dictated a need for three-dimensional modeling. A three-dimensional soil/structure interaction model was developed with the SASSI computer code. The development of three-dimensional models of the interfacing structures using the ANSYS code was also found to be necessary. 8 refs., 7 figs., 1 tab

  9. 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

  10. Hydrologic controls on basin-scale distribution of benthic invertebrates

    Science.gov (United States)

    Ceola, Serena; Bertuzzo, Enrico; Singer, Gabriel; Battin, Tom J.; Montanari, Alberto; Rinaldo, Andrea

    2014-04-01

    Streamflow variability is a major determinant of basin-scale distributions of benthic invertebrates. Here we present a novel procedure based on a probabilistic approach aiming at a spatially explicit quantitative assessment of benthic invertebrate abundance as derived from near-bed flow variability. Although the proposed approach neglects ecological determinants other than hydraulic ones, it is nevertheless relevant in view of its implications on the predictability of basin-scale patterns of organisms. In the present context, aquatic invertebrates are considered, given that they are widely employed as sensitive indicators of fluvial ecosystem health and human-induced perturbations. Moving from the analytical characterization of site-specific probability distribution functions of streamflow and bottom shear stress, we achieve a spatial extension to an entire stream network. Bottom shear stress distributions, coupled with habitat suitability curves derived from field studies, are used to produce maps of invertebrate suitability to shear stress conditions. Therefore, the proposed framework allows one to inspect the possible impacts on river ecology of human-induced perturbations of streamflow variability. We apply this framework to an Austrian river network for which rainfall and streamflow time series, river network hydraulic properties, and local information on invertebrate abundance for a limited number of sites are available. A comparison between observed species density versus modeled suitability to shear stress is also presented. Although the proposed strategy focuses on a single controlling factor and thus represents an ecological minimal model, it allows derivation of important implications for water resource management and fluvial ecosystem protection.

  11. Martian double ring basins - New observations

    Science.gov (United States)

    Wood, C. A.

    1980-01-01

    A description is presented of 18 Martian basins which were newly discovered on Viking photographs. A study of the basins reveals that diameter dependent differences in the morphology of Martian basins are more complex than previously realized. Basins have been classified according to ring morphology, and a diameter dependent sequence apparently exists. The obtained morphology sequence does not conform to the progression observed on the moon, Mercury, and earth. The small Martian basins are 50 to 100 km smaller than any basin on Mercury and the moon, supporting the view that they are unique to Mars. On earth there are significant terrain influences on crater and basin morphology that encourage the speculation that localized unique characteristics of the Martian crust led to basin formation at diameters where craters would normally be formed.

  12. WATSTORE Stream Flow Basin Characteristics File

    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. Hydrologic Sub-basins of Greenland

    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...

  14. 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.

  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. Effect of Volcano-Sedimentary Basin on the Earthquake Hazard Rate for the Gyumri City (armenia)

    Science.gov (United States)

    Durgaryan, R.; Avanesyan, M.; Babayan, S.; Gevorgyan, M.

    2012-12-01

    The main goal of the study was to conduct numerical modeling of the effects of local soil conditions in volcano-sedimentary basins. The studies focused on complex analyses of ground conditions. For this purpose , we collected a dense set of in-situ seismic measurements in Gyumri City test area to supplement the existing knowledge. We used this dataset to study the spatial correlation structure of S-wave velocities and predominant frequencies of micro-tremors in the Gyumri City, which is part of the Shirak volcano-sedimentary basin. Results of the measurements enabled us to constrain the scale of variation of S-wave velocity within volcano-sedimentary basins, which has important implications for accurate modeling of this effect and as a way to estimate soil conditions effects at different locations.

  17. 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

  18. K Basin spent fuel sludge treatment alternatives study. Volume 1, Regulatory 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. Volume 1 of this two-volume report describes the regulatory options for managing the sludges, including schedule and cost impacts, and assesses strategies for establishing a preferred path

  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. 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

  1. 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

  2. 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.

  3. Groundwater recharge and evolution in the Dunhuang Basin, northwestern China

    International Nuclear Information System (INIS)

    Groundwater recharge and evolution in the Quaternary aquifer beneath the Dunhuang Basin was investigated using chemical indicators, stable isotopes, and radiocarbon data to provide guidance for regional water management. The quality of groundwater and surface water is generally good with low salinity and it is unpolluted. The dissolution of halite and sylvite from fine-grained sediments controls concentrations of Na+ and K+ in the groundwater, but Na+/Cl? molar ratios >1 in all samples are also indicative of weathering of feldspar contributing to excess Na+. The dissolution of carbonate minerals yields Ca2+ to the groundwater, thereby exerting a strong influence on groundwater salinity. The ?18O and ?2H values in unconfined groundwater are enriched along the groundwater flow path from SW to NE. In contrast, confined groundwater was depleted in heavy isotopes, with mean values of ?10.4‰ ?18O and ?74.4‰ ?2H. Compared with the precipitation values, all of the groundwater samples were strongly depleted in heavy isotopes, indicating that modern direct recharge to the groundwater aquifers in the plains area is quite limited. The unconfined water is generally young with radiocarbon values of 64.9–79.6 pmc. In the northern basin, radiocarbon content in the confined groundwater is less than 15 pmc and an uncorrected age of ?15 ka, indicates that this ka, indicates that this groundwater was recharged during a humid climatic phases of the late Pleistocence or early Holocene. The results have important implications for inter-basin water allocation programmes and groundwater management in the Dunhuang Basin.

  4. 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...

  5. 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.

  6. Models of Fractal River Basins

    OpenAIRE

    Cieplak, Marek; Giacometti, Achille; Maritan, Amos; Rinaldo, Andrea; Rodriguez-iturbe, Ignacio; Banavar, Jayanth R.

    1998-01-01

    Two distinct models for self-similar and self-affine river basins are numerically investigated. They yield fractal aggregation patterns following non-trivial power laws in experimentally relevant distributions. Previous numerical estimates on the critical exponents, when existing, are confirmed and superseded. A physical motivation for both models in the present framework is also discussed.

  7. 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

  8. Lateral fluid flow in a compacting sand-shale sequence: South Caspian basin.

    Science.gov (United States)

    Bredehoeft, J.D.; Djevanshir, R.D.; Belitz, K.R.

    1988-01-01

    The South Caspian basin contains both sands and shales that have pore-fluid pressures substantially in excess of hydrostatic fluid pressure. Pore-pressure data from the South Caspian basin demonstrate that large differences in excess hydraulic head exist between sand and shale. The data indicate that sands are acting as drains for overlying and underlying compacting shales and that fluid flows laterally through the sand on a regional scale from the basin interior northward to points of discharge. The major driving force for the fluid movement is shale compaction. We present a first- order mathematical analysis in an effort to test if the permeability of the sands required to support a regional flow system is reasonable. The results of the analysis suggest regional sand permeabilities ranging from 1 to 30 md; a range that seems reasonable. This result supports the thesis that lateral fluid flow is occurring on a regional scale within the South Caspian basin. If vertical conduits for flow exist within the basin, they are sufficiently impermeable and do not provide a major outlet for the regional flow system. The lateral fluid flow within the sands implies that the stratigraphic sequence is divided into horizontal units that are hydraulically isolated from one another, a conclusion that has important implications for oil and gas migration.-Authors

  9. 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.

  10. 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.

  11. 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.

  12. Assymmetric eddy populations in adjacent basins - a high resolution numerical study of the Tyrrhenian and Ligurian Seas

    Science.gov (United States)

    Caldeira, R. M. A.; Couvelard, X.; Casella, E.; Vetrano, A.

    2012-11-01

    A high-resolution ocean circulation modelling system forced with a high-resolution numerical wind product was used to study the mesoscale and sub-mesoscale eddy population of the North-Western Mediterranean Sea, contrasting eddy-activity between the Tyrrhenian and Ligurian sub-basins. Numerical solutions reproduced some of the known regional dynamics, namely the occurrence and oceanic implications of Mistral events, the convective cell leeward of the Gulf of Lion, as well as the Balearic frontal system. Calculated transport across the Corsica Channel followed a similar trend, when compared to the transport computed from a moored current meter. The analysis of the results showed that surface eddy activity is mostly confined to the boundary-currents, whereas in the deeper layers most eddies are concentrated on the central-deeper part of the basins. The Liguro-Provençal basin shows a much higher concentration of intermediate and deep-water eddies, when compared to the Tyrrhenian basin. Sub-mesoscale surface eddies tend to merge and migrate vertically onto intermediate waters. Intense eddy activity in the boundary-current surrounding the Liguro-Provençal Gyre, concentrate high-productivity, manifested by higher concentrations of mean sea surface chlorophyll, in the central part of the gyre, defined herein as the Ligurian Productive Pool (LPP). On average, the Tyrrhenian was mostly oligotrophic except for a small productive vortice in the south-eastern (leeward) side of Corsica. The transport in the Tyrrhenian Gyre, and across the basin is one order of magnitude higher than the transport calculated for the Liguro-Provençal basin. A high concentration of eddies in the passage between the Balearic Archipelago and Sardinia suggests retention and longer residence times of nutrient rich water in the "Ligurian pool", compared to a "fast draining" Tyrrhenian basin. Previous studies support the cyclonic gyre circulation generated in the Liguro-Provençal basin but more studies are needed to address the surface and deep mesoscale activity of the Tyrrhenian basin.

  13. Experimental Drainage Basins in Israel

    Science.gov (United States)

    Laronne, J. B.; Lekach, J.; Cohen, H.; Gray, J.

    2002-12-01

    Within the hyper-arid to semiarid areas of Israel are three experimental drainage basins. They are the Nahal (stream in Hebrew) Yael, subdivided into five sub-basins, Rahaf-Qanna'im (main and tributary, respectively) and Eshtemoa. These basins vary in drainage area and climate, and in monitoring duration and type. All are drained by gravel-bed channels. As the size of monitored drainage area is limited, 3-4 additional representative basins covering areas of 300, 1000, 2000 and 8000 square kilometers will likely be implemented in the next decade. The basins have precipitation, runoff, sediment and fluviomorphological records. Each was conceived for differing purposes, but all share the common two objectives for the continuous monitoring: 1. Many hydrological issues may be approached if, and only if, there are prototype databases on a wide spectrum of hydrological processes; and 2. There is a need for long-term records to assess large floods and subsequent hydrologic and geomorphic recovery. Lessons derived from a large number of research projects on these experimental basins focus on characteristics of runoff in arid climates. For example, the effect of the spatial distribution of rainfall on runoff generation becomes increasingly important with aridity. Rainfall angle on hillslopes and storm intensity and direction derived from rainfall recorders and radar backscatter are crucial for explanation of runoff response. Runoff hydrographs tend to have more bores, shorter-duration peaks, briefer recessions, longer dry periods, and are more variable in terms of flood volume and peaks with increased aridity. Suspended-sediment fluxes, yields and concentrations are relatively large in the semiarid realm, reaching maxima at the beginning of a flood season and after long dry spells. Bedload fluxes are exceptionally high from dryland basins in which hillslopes are minimally vegetated and where bedload transport takes place in channels lacking an armor layer. Bedload/suspended-sediment load ratios increase with aridity. Bedload yield may represent up to 70% of the total load. Hillslope to channel connectivity is high in drylands. In the hyperarid region suspended-sediment sources are hillslopes and the coarser, sandy fraction of the channel bedmaterial. The depth of channel bed activity is indicated by a fluvio-pedogenic unit beneath the channel surface. National and regional hydrological research needs will dictate future global monitoring in experimental basins. International collaboration may bring about considerable cost reduction by exclusion of monitoring aspects that can be evaluated based on the monitoring in other, similar conditions. Advanced international collaboration on validation and calibration of and consistency in monitoring means, as well as syntheses of lessons derived from international collaboration, such as from an International Watershed Research Network, are required for maximizing our understanding of water and sediment responses in varied global regions.

  14. Coastal inlets and tidal basins:

    OpenAIRE

    Vriend, H.J.; Dronkers, J.; M.J.F. Stive; Van Dongeren, A.; Wang, J.H.

    2002-01-01

    lecture note: Tidal inlets and their associated basins (lagoons) are a common feature of lowland coasts all around the world. A significant part ofthe world's coastlines is formed by barrier island coasts, and most other tidal coasts are interrupted by estuaries and lagoon inlets. These tidal systems play a crucial role in the sediment budget ofthe coastal zone and thus influence the long-term coastal evolution. From a morphological point of view, tidal inlets form highly dynamical systems, w...

  15. K West Basin canister survey

    International Nuclear Information System (INIS)

    A survey was conducted of the K West Basin to determine the distribution of canister types that contain the irradiated N Reactor fuel. An underwater camera was used to conduct the survey during June 1998, and the results were recorded on videotape. A full row-by-row survey of the entire basin was performed, with the distinction between aluminum and stainless steel Mark 1 canisters made by the presence or absence of steel rings on the canister trunions (aluminum canisters have the steel rings). The results of the survey are presented in tables and figures. Grid maps of the three bays show the canister lid ID number and the canister type in each location that contained fuel. The following abbreviations are used in the grid maps for canister type designation: IA = Mark 1 aluminum, IS = Mark 1 stainless steel, and 2 = Mark 2 stainless steel. An overall summary of the canister distribution survey is presented in Table 1. The total number of canisters found to contain fuel was 3842, with 20% being Mark 1 Al, 25% being Mark 1 SS, and 55% being Mark 2 SS. The aluminum canisters were predominantly located in the East and West bays of the basin

  16. Uranium geochemistry of Orca Basin

    International Nuclear Information System (INIS)

    Orca Basin, an anoxic, brine-filled depression at a depth of 2200 m in the Northwestern Gulf of Mexico continental slope, has been studied with respect to its uranium geochemistry. Uranium concentration profiles for four cores from within the basin were determined by delayed-neutron counting. Uranium concentrations ranged from 2.1 to 4.1 ppm on a salt-free and carbonate-corrected basis. The highest uranium concentrations were associated with the lowest percentage and delta13C organic carbon values. For comparison, cores from the brine-filled Suakin and Atlantis II Deeps, both in the Red Sea, were also analyzed. Uranium concentrations ranged from 1.2 to 2.6 ppm in the Suakin Deep and from 8.0 to 11.0 ppm in the Atlantis II Deep. No significant correlation was found between uranium concentrations and organic carbon concentrations and delta13C values for these cores. Although anoxic conditions are necessary for significant uranium uptake by non-carbonate marine sediments, other factors such as dilution by rapidly depositing materials and uranium supply via mixing and diffusion across density gradients may be as important in determining uranium concentrations in hypersaline basin sediments. (author)

  17. Drainage basin delineations for selected USGS streamflow-gaging stations in Virginia (Drainage_Basin)

    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. STILLING BASINS BELOW OUTLET WORKS – AN OVERVIEW

    Directory of Open Access Journals (Sweden)

    H L Tiwari,

    2010-11-01

    Full Text Available A stilling basins are transition structures constructed to dissipate excess energy confined by high velocity flow at the outlet of conduit or tunnel so that the flow beyond the basin does not endanger the stability of bed and banks of downstream channel. In a stilling basin kinetic energy causes turbulences and it is ultimately lost as heat and sound energy. there are several types of stilling basins which are used in various hydraulic structures like dam, canal, culvert etc. The type of stilling basin most suitable at a particular location mainly depends upon initial Froude Number and initial velocity of flow. This paper covers design principles and features of various stilling basins used for outlet works.

  19. Geology and deposits of the Serenitatis basin

    Science.gov (United States)

    Spudis, Paul D.; Hawke, B. Ray; Lucey, Paul G.

    1993-01-01

    The Serenitatis basin is prominent on the near side of the Moon, just east of Mare Imbrium. Originally thought to be one of the oldest lunar basins, re-interpretation of both geological relations and Apollo 17 isotopic data suggest instead that Serenitatis is one of the youngest basins, having formed in the Nectarian Period about 3.87 Ga ago. As part of our continuing effort to understand the geology of multi-ring basins on the Moon and to use basins as probes of the deep lunar crust, we here report results for the Serenitatis basin. Our examination of Serenitatis was stimulated in part by a new effort to re-examine the geology of the Apollo 17 landing site.

  20. Stratigraphy and structure of the Altar basin of NW Sonora: Implications for the history of the Colorado River delta and the Salton trough / Estratigrafía y estructura de la cuenca de Altar del NW de Sonora: implicaciones para la historia del delta del Río Colorado y de la cuenca Salton

    Scientific Electronic Library Online (English)

    Martín, Pacheco; Arturo, Martín-Barajas; Wilfred, Elders; Juan Manuel, Espinosa-Cardeña; Javier, Helenes; Alberto, Segura.

    Full Text Available El Desierto de Altar en el noroeste de Sonora, contiene una cuenca subsidiaria ubicada en la parte inactiva del delta del Rio Colorado. El registro sedimentario ilustra cómo el delta progradó sobre una cuenca marina estructuralmente independiente del Mioceno tardío, hacia la terminación norte del Go [...] lfo de California. La interpretación de datos de afloramientos, datos de siete pozos exploratorios y seis líneas sísmicas analógicas de Petróleos Mexicanos (PEMEX), además de datos magnéticos y gravimétricos compilados de diversas fuentes, indican la existencia de tres secuencias sedimentarias, A, B y C, con más de 5 km de espesor y con una distribución de escala regional. La secuencia inferior (secuencia A) es una unidad de lutita marina de ambiente nerítico externo. Esta unidad grada a una potente secuencia de lodolita, limolita y arenisca (secuencia B), la cual a su vez grada a una secuencia de arena poco consolidada (secuencia C). Las secuencias B y C se interpretan como parte del sistema submarino y subaéreo, respectivamente, que progradó hacia la cuenca marina. Afloramientos de una secuencia arenosa de corte y relleno, interpretada como depósitos fluviodeltaicos y expuesta a lo largo de la costa de Sonora, son consistentes con una interpretación en donde la secuencia C forma parte de la planicie fluvial del Río Colorado. El contacto discordante de la base de la secuencia A sobre el basamento cristalino y la ausencia de depósitos premarinos se interpreta como el resultado del transporte tectónico a lo largo de una falla de despegue con transporte de la placa superior hacia el nor-noroeste. La subsidencia en la cuenca de Altar cesó debido al cambio en la localización de la actividad tectónica de la falla Altar a la falla Cerro Prieto, así como al cambio en el cauce del Río Colorado hacia el Valle de Mexicali durante el Pleistoceno. Abstract in english The Altar basin in northwestern Sonora, Mexico, is a subsidiary basin forming a now inactive part of the Colorado River delta. Its sedimentary record illustrates how the delta prograded in the last 4-5 Ma overa late Miocene, structurally distinct, marine basin at the northern end of the Gulf of Cali [...] fornia. Our interpretation of outcrop data, and data from seven exploratory wells, six analog seismic lines of Petróleos Mexicanos (PEMEX), and magnetic and gravity surveys from various sources indicates the existence of three sedimentary sequences, A, B, and C, which can be correlated at regional scale and have a thickness >5 km at the basin depocenter. The lower sedimentary sequence A is a shale unit representing open marine conditions (outer neritic). It grades into a thick sequence of interstratified mudstone, siltstone, and sandstone (sequence B), which grades in turn into poorly consolidated sand (sequence C). Extensive outcrops of a sandy, cut and fill succession exposed along the coast of Sonora are consistent with sequences B and C being the sub-aqueous and the sub-aereal parts of the delta, respectively. A contact at the base of the sequence A, where pre-marine continental deposits are missing, and where the marine sequence overlies crystalline basement, is interpreted as tectonic transport along a top-to-the-norihwest detachment fault. The Altar basin became inactive as result of the westward shift in the locus of tectonic activity from the Altar fault to the Cerro Prieto fault, coupled with realignments in the course of the Colorado River during Pleistocene time.

  1. Deformed river basins of the Himalaya

    Science.gov (United States)

    Walcott, R.; Sinclair, H.

    2009-04-01

    Identification of the controls on basin morphology in mountain belts is needed to understand how landscapes evolve under changing conditions. Although river basins vary enormously in area, many of their morphological relationships, such as Hack's law, are scale invariant irrespective of mountain type. This suggests that, in most mountain belts, the fundamental process(es) that control basin morphology are also scale invariant and therefore largely insensitive to variations in tectonic activity. However, river basins in the Himalaya are anomalously wide when compared with basins developed on the flanks of other semi-linear ranges. We present a detailed study of Himalayan river basin morphology to determine how the evolution of this orogen may have influenced the shape of these unusual basins. We investigate, in particular, the statistical geometric properties of basins, such as the length, width and area of basins, with respect to the scale and the location of the basin within the mountain belt. Our results show that the anomalously wide basins found over much of the Himalaya have a limited scale range and distribution. These data therefore provide an indication of the significant control that the evolution of this mountain range has had on basin morphology at the local scale. The fact that these catchments have departed from what is perceived as a stable scaling relationship implies that, while their rivers can incise at a rate broadly comparable to the rate of rock uplift, their drainage divides can not migrate fast enough to reconfigure in response to tectonic shortening. As a result, long-term crustal shortening has significantly deformed the river network within the central and western Himalaya.

  2. 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.

  3. 75 FR 66389 - Colorado River Basin Salinity Control Advisory Council

    Science.gov (United States)

    2010-10-28

    ...Bureau of Reclamation Colorado River Basin Salinity Control Advisory Council AGENCY: Bureau...SUMMARY: The Colorado River Basin Salinity Control Advisory Council (Council) was established by the Colorado River Basin Salinity Control Act of 1974 (Pub. L....

  4. 76 FR 61382 - Colorado River Basin Salinity Control Advisory Council

    Science.gov (United States)

    2011-10-04

    ...Bureau of Reclamation Colorado River Basin Salinity Control Advisory Council AGENCY: Bureau...SUMMARY: The Colorado River Basin Salinity Control Advisory Council (Council) was established by the Colorado River Basin Salinity Control Act of 1974 (Pub. L....

  5. 77 FR 23508 - Colorado River Basin Salinity Control Advisory Council

    Science.gov (United States)

    2012-04-19

    ...Bureau of Reclamation Colorado River Basin Salinity Control Advisory Council AGENCY: Bureau...SUMMARY: The Colorado River Basin Salinity Control Advisory Council (Council) was established by the Colorado River Basin Salinity Control Act of 1974 (Pub. L....

  6. 75 FR 27360 - Colorado River Basin Salinity Control Advisory Council

    Science.gov (United States)

    2010-05-14

    ...Bureau of Reclamation Colorado River Basin Salinity Control Advisory Council AGENCY: Bureau...SUMMARY: The Colorado River Basin Salinity Control Advisory Council (Council) was established by the Colorado River Basin Salinity Control Act of 1974 (Pub. L....

  7. 78 FR 23784 - Colorado River Basin Salinity Control Advisory Council

    Science.gov (United States)

    2013-04-22

    ...Bureau of Reclamation Colorado River Basin Salinity Control Advisory Council AGENCY: Bureau...SUMMARY: The Colorado River Basin Salinity Control Advisory Council (Council) was established by the Colorado River Basin Salinity Control Act of 1974 (Public Law...

  8. Tectonic setting of the San Juan basin in the Jurassic

    International Nuclear Information System (INIS)

    In the Middle and Late Jurassic, the structural configuration of the area occupied by the San Juan basin was different from the present-day configuration, which developed in response to Laramide deformation in the latest Cretaceous to early Teritary. An isopach map indicates a thickening of Middle to Upper Jurassic strata near the southern margin of the area. The thickening is attributed to downwarping, mainly in the Jurassic, which may have controlled depositional patterns and influenced the distribution of primary uranium ore deposits in the host rocks of the Jurassic Morrison Formation. Paleotectonic reconstruction indicates the existence of a magmatic arc immediately west of the Colorado Plateau in the Jurassic. Jurassic folding in the basin and magmatic activity in the arc have important implications bearing on the uranium geology of the area. The folding probably exerted some control on depositional trends in the host rocks which, in turn, influenced the distribution of uranium deposits in them. Volcanism in the magmatic arc supplied silicic ash that may be the source of some, if not all, of the uranium in the host rocks

  9. Origin and occurrence of crude oils in the Zhu1 sub-basin, Pearl River Mouth Basin, China

    Science.gov (United States)

    Hu, Yue; Hao, Fang; Zhu, Junzhang; Tian, Jinqiang; Ji, Yubing

    2015-01-01

    The origin of the seventeen major oil fields in the Zhu1 sub-basin, Pearl River Mouth Basin (PRMB) was studied based on the results of Rock-Eval pyrolysis on more than 370 samples and biomarker analysis on 31 source rock samples and 63 oil samples. The two possible source rock intervals have different biomarker assemblages and were deposited in different environments. The Wenchang Formation (E2w, 56.5-32 Ma) is characterized mainly by low C19/C23 tricyclic terpane (0.4) ratios, and were deposited in anoxic to suboxic environments with important contribution from Pediastrum and Dinoflagellates. The Enping Formation (E3e, 32-30 Ma) has high C19/C23 tricyclic terpane, high C24 tetracyclic terpane/??C30 hopane, widely variable yet overally high bicadinane-T/??C30 hopane and low 4-methyl steranes/?C29 steranes ratios, and were deposited in freshwater lacustrine to swamp conditions with significant terrigenous organic matter input. According to oil-source correlation, three oil classes can be identified in the Zhu1 sub-basin. Class 1 oil is E2w-derived and occurs widely. Class 2 oil is E3e-derived and refers to oils from F field in the north of the Huizhou depression. Class 3 oil is a mixture of oils generated from E2w and E3e, only distributed in the Huizhou depression and on its southern margin. The petroleum distribution pattern is mainly controlled by the distribution of source rocks and the migration pathways of oils. This research has important implications for future exploration.

  10. Stratigraphic Signatures of Forearc Basin Formation Mechanisms

    Science.gov (United States)

    Mannu, U.; Ueda, K.; Gerya, T.; Willett, S.; Strasser, M.

    2014-12-01

    Forearc basins are loci of active sedimentation above the landward portion of accretionary prisms. Although these basins typically remain separated from the frontal prism by a forearc high, their evolution has a significant impact on the structure and deformation of the entire wedge. Formation of forearc basins has been proposed as a consequence of changes in wedge stability due to an increase of slab dip in subduction zones. Another hypothesis attributes this to higher hinterland sedimentation, which causes the rear of the wedge to stabilize and eventually develop a forearc basin. Basin stratigraphic architecture, revealed by high-resolution reflection seismic data and borehole data allows interpretation of structural development of the accretionary prism and associated basins with the goal of determining the underlying driving mechanism(s) of basin formation. In this study we supplement data interpretation with thermo-mechanical numerical models including high-resolution isochronal surface tracking to visualize the developing stratigraphy of basins that develop in subduction zone and wedge dynamic models. We use a dynamic 2D thermo mechanical model incorporating surface processes, strain weakening and sediment subduction. The model is a modification of I2VIS model, which is based on conservative, fully staggered finite differences and a non-diffusive marker- in-cell technique capable of modelling mantle convection. In the model different driving mechanisms for basin formation can be explored. Stratigraphic simulations obtained by isochronal surface tracking are compared to reflection pattern and stratigraphy of seismic and borehole data, respectively. Initial results from a model roughly representing the Nankai Trough Subduction Zone offshore Japan are compared to available seismic and Integrated Ocean Drilling (IODP) data. A calibrated model predicting forearc basin stratigraphy will be used to discern the underlying process of basins formation and wedge dynamics.

  11. Evolution of the West Siberian Basin

    Energy Technology Data Exchange (ETDEWEB)

    Vyssotski, A.V. [Chevron, 1500 Louisiana Street, Houston (United States); Vyssotski, V.N. [TNK-BP, 1 Arbat St, Moscow 119019 (Russian Federation); Nezhdanov, A.A. [OOO TyumenNIIgiprogas, 2 Vorovskogo Str., Tyumen 625019 (Russian Federation)

    2006-01-01

    The West Siberian Basin is one of the largest intra-cratonic basins of the world and an important hydrocarbon province of Russia. Perhaps the most important geologic event in Siberia was the emplacement of basalts around {approx} 250Ma (i.e. Permo-Triassic boundary) covering an area of about 5x10{sup 6} km{sup 2}. This volcanism may be responsible for a mass extinction that occurred around Permian-Triassic time. The pre-basaltic rifting event was limited to the north-northeastern sector of the basin. Initial basin wide subsidence took place in the Jurassic as a result of which the western part of Siberia became the West Siberian Basin bounded by uplifts to the east and to the west. One of the surprising aspects of the West Siberian Basin is the abundance of sub-vertical faults believed to be result of strike-slip movement. While intra-plate inversions and fault reactivation structures have been observed in many cratons, sub-vertical faults observed in the West Siberian Basin are unique because of their geometries and abundance. The differentiation between the effects of tectonics and eustasy in cratonic basins is simple-the global eustatic signal is basin-wide with regional and local tectonics playing an overprinting role. Thus, the Middle Jurassic-Turonian 1st, 2nd, and 3rd order cycles in the West Siberian Basin were primarily driven by eustasy. The Middle Jurassic-Turonian series can be subdivided into two second-order and 16 third-order transgressive-regressive cycles (within dataset extent). Fourth-order cycles appear to be controlled by delta shifting. Although extensively studied, a number of fundamental questions regarding the origin and evolution of the West Siberian Basin remain unresolved or poorly documented in the literature. [Author].

  12. Basin-scale relations via conditioning

    Science.gov (United States)

    Troutman, B.M.; Karlinger, M.R.; Guertin, D.P.

    1989-01-01

    A rainfall-runoff model is used in conjunction with a probabilistic description of the input to this model to obtain simple regression-like relations for basin runoff in terms of basin and storm characteristics. These relations, similar to those sought in regionalization studies, are computed by evaluating the conditional distribution of model output given basin and storm characteristics. This method of conditioning provides a general way of examining model sensitivity to various components of model input. The resulting relations may be expected to resemble corresponding relations obtained by regionalization using actual runoff to the extent that the rainfall-runoff model and the model input specification are physically realistic. The probabilistic description of model input is an extension of so-called "random-model" of channel networks and involves postulating an ensemble of basins and associated probability distributions that mimic the variability of basin characteristics seen in nature. Application is made to small basins in the State of Wyoming. Parameters of the input variable distribution are estimated using data from Wyoming, and basin-scale relations are estimated both, parametrically and nonparametrically using model-generated runoff from simulated basins. Resulting basin-scale relations involving annual flood quantiles are in reasonable agreement with those presented in a previous regionalization study, but error estimates are smaller than those in the previous study, an artifact of the simplicity of the rainfall-runoff model used in this paper. We also obtain relations for peak of the instantaneous unit hydrograph which agree fairly well with theoretical relations given in the literature. Finally, we explore the issues of sensitivity of basin-scale, relations and error estimates to parameterization of the model input probability distribution and of how this sensitivity is related to making inferences about a particular ungaged basin. ?? 1989 Springer-Verlag.

  13. Natural CO{sub 2} migrations in the South-Eastern Basin of France: implications for the CO{sub 2} storage in sedimentary formations; Contribution a la connaissance des migrations de CO{sub 2} naturel dans le Bassin du Sud-Est de la France: enseignements pour le stockage geologique du CO{sub 2} dans les reservoirs sedimentaires

    Energy Technology Data Exchange (ETDEWEB)

    Rubert, Y.

    2009-03-15

    Study of natural CO{sub 2} analogues brings key informations on the factors governing the long term stability/instability of future anthropogenic CO{sub 2} storages. The main objective of this work, through the study of cores from V.Mo.2 well crosscutting the Montmiral natural reservoir (Valence Basin, France), is to trace the deep CO{sub 2} migrations in fractures. Petrographic, geochemical and micro-thermometric studies of the V.Mo.2 cores were thus performed in order: 1) to describe the reservoir filling conditions and 2) to detect possible CO{sub 2}-leakage through the sediments overlying the reservoir. Fluid inclusions from the Paleozoic crystalline basement record the progressive unmixing of a hot homogeneous aquo-carbonic fluid. The Montmiral reservoir was therefore probably fed by a CO{sub 2}-enriched gas component at the Late Cretaceous-Paleogene. The study of the sedimentary column in V.Mo.2 well, demonstrates that the CO{sub 2} did not migrate towards the surface through the thick marly unit (Domerian-Middle Oxfordian). These marls have acted as an impermeable barrier that prevented the upward migration of fluids. Two main stages of fluid circulation have been recognized: 1) an ante- Callovian one related to the Tethysian extension 2) a tertiary stage during which the upper units underwent a karstification, with CO{sub 2} leakage related but which remained confined into the deeper parts of the Valence Basin. Since the Paleogene, the Montmiral reservoir has apparently remained stable, despite the Pyrenean and alpine orogeneses. This is mainly due to the efficient seal formed by the thick marly levels and also to the local structuration in faulted blocks which apparently acted as efficient lateral barriers. (author)

  14. Free energy basin-hopping

    Science.gov (United States)

    Sutherland-Cash, K. H.; Wales, D. J.; Chakrabarti, D.

    2015-04-01

    A global optimisation scheme is presented using basin-hopping with the acceptance criterion based on approximate free energy for the corresponding local minima of the potential energy. The method is illustrated for atomic and colloidal clusters and peptides to examine how the predicted global free energy minimum changes with temperature. Using estimates for the local free energies based on harmonic vibrational densities of states provides a computationally effective framework for predicting trends in structure at finite temperature. The resulting scheme represents a powerful tool for exploration of energy landscapes throughout molecular science.

  15. K Basins Field Verification Program

    International Nuclear Information System (INIS)

    The Field Verification Program establishes a uniform and systematic process to ensure that technical information depicted on selected engineering drawings accurately reflects the actual existing physical configuration. This document defines the Field Verification Program necessary to perform the field walkdown and inspection process that identifies the physical configuration of the systems required to support the mission objectives of K Basins. This program is intended to provide an accurate accounting of the actual field configuration by documenting the as-found information on a controlled drawing

  16. 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.

  17. 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 thedominated 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.

  18. Monitoring and evaluation of smolt migration in the Columbia Basin, Volume II: Evaluation of the 1996 predictions of the run-timing of wild migrant subyearling chinook in the Snake River Basin using Program RealTime.; TOPICAL

    International Nuclear Information System (INIS)

    This project was initiated in 1991 in response to the Endangered Species Act (ESA) listings in the Snake River Basin of the Columbia River Basin. Primary objectives and management implications of this project include: (1)to address the need for further synthesis of historical tagging and other biological information to improve understanding and identify future research and analysis needs; (2)to assist in the development of improved monitoring capabilities, statistical methodologies and software tools to aid management in optimizing operational and fish passage strategies to maximize the protection and survival of listed threatened and endangered Snake River salmon populations and other listed and nonlisted stocks in the Columbia River Basin; (3)to design better analysis tools for evaluation programs; and (4)to provide statistical support to the Bonneville Power Administration and the Northwest fisheries community

  19. Geology Fieldnotes: Great Basin National Park, Nevada

    Science.gov (United States)

    This Great Basin National Park site contains park geology information, park maps, visitor information, and teacher features (educational resources and links for teaching geology using National Park examples). The park geology section discusses the region's biogeography, glacial history, and the Lehman Caves. A park map and a features/relief map of the Great Basin National Park are included.

  20. 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

  1. Fractal basins in an ecological model

    Directory of Open Access Journals (Sweden)

    I. Djellit

    2013-09-01

    Full Text Available Complex dynamics is detected in an ecological model of host-parasitoid interaction. It illustrates fractalization of basins with self-similarity and chaotic attractors. This paper describes these dynamic behaviors, bifurcations, and chaos. Fractals basins are displayed by numerical simulations.

  2. The influence of late Miocene exhumation on the petroleum systems of the greater Caucasus foreland basins

    International Nuclear Information System (INIS)

    Full text: Northwards impingement of Arabia during the Cenozoic led to the inversion of the Mesozoic Greater Caucasus Basin and the associated development of areas of enhanced subsidence. However, there is great debate regarding the timing of initiation of thrusting and uplift in the Caucasus region.Traditionally, ages ranging from Middle Eocene through to Middle Miocene have been proposed.More recently. It has become clear that although deformation and flexural subsidence may have initiated during the Late Miocene to Pliocene.The potential causative mechanisms for this late uplift and exhumation did not begin until the Late Miocene to Pliocene.The potential causative mechanisms for this late uplift event have been identified.The late Miocene to Pliocene event influenced a broad region and had important implications for reservoir rock deposition and the generation,migration,trapping and preservation of hydrocarbons in the surrounding basins (e.g. Indolo-Kuban,Terek-Caspian, South Caspian, Kura-Kartli, Rion, Black Sea).One area of particular interest is the development of the Stavropol Arch through time,since foreland basins are presently restricted to the Indolo-Kuban and Terek-Caspian Sub-basins.The Stavropol Arch lies immediately north of the central, most elevated parts of the Caucasus Mountains and separates the main areas of enhanced foreland subsidence.Although in most palaeogeographic reconstructions of the area, the Stavropol Arch is shown as an uplifted massiavropol Arch is shown as an uplifted massif during much of the Mesozoic and Lower Cenozoic, it seems likely from recent studies that it is a feature of Late Miocene to Pliocene exhumation.One major potential implication is that an Oligocene to Miocene (foreland) succession developed in a major basin across the whole region north of the Greater Caucasus.Much of this was subsequently eroded from the Stavropol Arch during uplift and exhumation, separating the Indolo-Kuban and Terek-Caspian foreland basins.From qualitative section balancing we would estimate erosion of at least 4 km of overburden since the Late Miocene.This uplift event can also be recognized from the Greater Caucasus themselves and from the intramontane basins to the south of the foldbelt.

  3. Critical Concavity of a Drainage Basin for Steady-State

    Science.gov (United States)

    Byun, Jongmin; Paik, Kyungrock

    2015-04-01

    Longitudinal profiles of natural streams are known to show concave forms. Saying A as drainage area, channel gradient S can be expressed as the power-law, S?A-? (Flint, 1974), which is one of the scale-invariant features of drainage basin. According to literature, ? of most natural streams falls into a narrow range (0.4 power-law scaling relationships reported in natural drainage basins?' To answer above questions, we analytically derive ? for a steady-state drainage basin following Lane's equilibrium (Lane, 1955) throughout the corridor and named this specific case as the 'critical concavity'. In the derivation, sediment transport capacity is estimated by unit stream power model (Yang, 1976), yielding a power function of upstream area. Stability of channel at a local point occurs when incoming flux equals outgoing flux at the point. Therefore, given the drainage at steady-state where all channel beds are stable, the exponent of the power function should be zero. From this, we can determine the critical concavity. Considering ranges of variables associated in this derivation, critical concavity cannot be resolved as a single definite value, rather a range of critical concavity is suggested. This range well agrees with the widely reported range of ? (0.4 power-laws such as hydraulic geometry (Leopold and Maddock, 1953), dominant discharge-drainage area (Knighton et al., 1999), and concavity, are coupled into the power-law framework of stream power sediment transport model. This allows us to explore close relationships between their power-law exponents: their relative roles and sensitivity. Detailed analysis and implications will be presented. References Flint, J. J., 1974, Stream gradient as a function of order, magnitude, and discharge, Water Resources Research, 10, 969-973. Knighton, A. D., 1999, Downstream variation in stream power, Geomorphology, 29, 293-306. Lane, E. W., 1955, The importance of fluvial morphology in hydraulic engineering, American Society of Civil Engineers, Proceedings, 81, 1-17 Leopold, L. B., Maddock, T., 1953, The hydraulic geometry of stream channels and some physiographic implications, United States Government Printing Office, 1953. Tucker, G. E., Whipple, K. X., 2002, Topographic outcomes predicted by stream erosion models: Sensitivity analysis and intermodel comparison, Journal of Geophysical Research, 107(B9), 2179, doi:10.1029/2001JB000162, 2002. Yang, C. T., 1976, Minimum unit stream power and fluvial hydraulics, Journal of Hydraulics Division, ASCE 102, 919-934.

  4. 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

  5. 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

  6. 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.

  7. K-Basins isolation barriers summary report

    International Nuclear Information System (INIS)

    The purpose of this report is to provide an information summary for the 100-K Area fuel storage basins design change. The design change was made to resolve an unreviewed safety question related to potential water leakage from the basin following a design basis earthquake. The design change consists of installing isolation barriers in the K-East and K-West Basins. The barriers are installed in each basin to isolate the fuel storage portion of the basin from the location of the potential seismic induced leak. The summary represented by this report provides information on the issue, the courses of corrective action, the technical work to support the corrective action, and the fabrication, installation, testing of the isolation barriers

  8. 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.

  9. 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.

  10. Building a three-dimensional geological model of the Pegasus Basin (offshore New Zealand) with the aim of improving our understanding of gas hydrate distribution

    Science.gov (United States)

    Crutchley, G. J.; Barnes, P.; Kroeger, K. F.; Hill, M.; Mountjoy, J. J.; Pecher, I. A.

    2014-12-01

    The Pegasus Basin, on the southern end of New Zealand's Hikurangi margin, developed as a passive margin from the end of subduction along the Chatham Rise around 105 Ma to the initiation of the modern plate boundary around 25 Ma. Multi-channel seismic reflection data acquired by the New Zealand government in 2009 and 2010 show well-developed bottom-simulating reflections (BSRs) throughout the basin and also indications for deeply-sourced fluid migration. We have used the seismic data, together with previously published age constraints, to identify and map key stratigraphic horizons from the ancient subduction margin (on the southeast), through the sedimentary basin, and up onto the modern subduction margin (on the northwest). We have also used BSRs to map the extent of the gas hydrate system throughout the basin. These interpretations are being used to construct a 3D geological model of the basin that will be converted to depth using seismic velocities from the available data. The geological model will provide the basis for modelling fluid flow processes through the basin and ultimately to simulate gas hydrate formation using Petromod. We will present the latest results of this project and outline the implications for gas hydrate formation in the Pegasus Basin.

  11. Seafloor Spreading Morphology in the Lau Basin: Insights Into the Interplay Between Mantle Chemistry, Crustal Accretion and Back-arc Basin Evolution

    Science.gov (United States)

    Martinez, F.; Taylor, B.

    2006-12-01

    The mantle above subduction zones can have systematic spatial gradients in chemistry with distance from the arc volcanic front (AVF) as a result of metasomatic additions from the slab and melt extraction processes at and behind the AVF. Back-arc spreading centers that transect these gradients are key sites at which to examine the interplay between mantle chemistry and crustal accretion processes. A favorable example is the linear 400-km-long back-arc Eastern Lau Spreading Center (ELSC), which southward progressively approaches the AVF from 100 to within 40 km. New Ridge 2000 mapping surveys compiled together with other data reveal the character of active ELSC seafloor spreading and permit insights into the origin of older flanking basin crust. ELSC axial morphology undergoes large and abrupt changes with arc proximity, from a deep (> 3000 m), flat and faulted seafloor to shallow (~ 1600 m), peaked volcanic highs, even as spreading rates decrease from 97 to 39 mm/yr. Concomitant systematic changes in lava chemistry from basaltic to andesitic indicate strong links between mantle chemistry, magmatic productivity of the spreading center, crustal structure, and ridge and flanking seafloor morphology. Morphologic contrasts between the ELSC and mid-ocean ridges, where mantle chemistry is generally more uniform, show that mantle chemistry is a predominant control on back-arc spreading characteristics. The diverse active spreading morphologies of the ELSC have important implications for the evolution of the Lau Basin. They indicate that the complex seafloor morphologies found within the basin may not result, as previously proposed, from a two-phase evolution from protracted tectonic arc rifting to organized seafloor spreading. Rather, the new mapping data show that the complex landforms of the older western basin have similar morphologic counterparts in the magmatically accreted crust of the present ELSC. These observations support a revised model of Lau Basin evolution in which essentially the entire basin formed by magmatic crustal accretion but in which crustal thickness and morphology reflect the changing locus of the magmatic centers as the basin opened with respect to a mantle wedge of varying chemistry.

  12. Cost Implications in Achieving Alternative Water Quality Targets

    Science.gov (United States)

    Schleich, Joachim; White, David; Stephenson, Kurt

    1996-04-01

    Excessive nutrient loading poses significant water quality problems in many water bodies across the country. An important question that must be addressed when nutrient reduction policies are devised is where nutrient reduction targets will be applied within the watershed. This paper examines the cost implications of establishing three possible nutrient reduction targets in different locations along the Fox-Wolf River basin in northeast Wisconsin. A linear programming model calculates the total cost of achieving a 50% phosphorus load reduction target established in various locations throughout the basin. Two strategies establish phosphorus reduction targets for each of the 41 subwatersheds, and the third approach establishes a single 50% target reduction at Green Bay for the entire watershed. The results indicate that achieving target phosphorus reductions at the subwatershed level is over 4 times more expensive than achieving the same percentage phosphorus reduction for the watershed as a whole.

  13. 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 oN 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

  14. Deep structure of hyperextended basins offshore Norway

    Science.gov (United States)

    Terje Osmundsen, Per; Peron-pinvidic, Gwenn; Ebbing, Jorg; Erratt, Duncan

    2014-05-01

    The 3D architecture of rifted margins is controlled by lateral variations in the location of domain boundaries and displacement gradients along the structures that define them. The deep structure of the Mid-Norway rifted margin is characterized by a fault-controlled necking domain, a hyperextended block-faulted area of variable width and an array of distal detachment breakaways that border areas that resemble exhumation domains. From Jurassic to Late Cretaceous times, the suite of extensional faults and basins appear to show a temporal migration towards the future location of breakup, but parts of the deep margin provide evidence for a complex evolution with more than one phase of extensional faulting in the deep basin areas, and with `out of sequence' faults that cut and deactivated earlier detachments. A number of distinct extensional basin types evolved that can be identified and classified according to their structural setting and location in the margin system. In the necking domain, supradetachment basins became perched on rider blocks on gently dipping detachment faults that were abandoned in shallow structural positions as they were incised by a second generation of detachments. The taper break or coupling basin is the innermost basin in the distal margin and occupies a position at the base of a tens of kilometres wide crustal slope, defined by the faults associated with construction of the necking domain. Arrays of very deep half-graben basins are associated with hyperextended crust outboard of the necking domain. Outboard of the distal detachment breakaway, or the exhumation limit in the case of mantle windows, supradetachment basins are associated with extensional allochthon and multiply extended ridges. The necking and distal domains present variable contact relationships to the overlying sag basin in terms of downlap, onlap and erosional unconformities. The combined stratal architecture reflects the position with respect to the various margin domains.

  15. 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,...

  16. Delaware Basin Monitoring Annual Report

    Energy Technology Data Exchange (ETDEWEB)

    Washington Regulatory and Environmental Services; Washington TRU Solutions LLC

    2005-09-30

    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.

  17. 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)