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Sample records for basin northern pikeminnow

  1. Early life history of the northern pikeminnow in the lower Columbia River basin

    USGS Publications Warehouse

    Gadomski, D.M.; Barfoot, C.A.; Bayer, J.M.; Poe, T.P.

    2001-01-01

    The northern pikeminnow Ptychocheilus oregonensis is a large, native cyprinid in the Columbia River basin that has persisted in spite of substantial habitat alterations. During the months of June to September 1993-1996, we investigated the temporal and spatial patterns of northern pikeminnow spawning, along with describing larval drift and characterizing larval and early juvenile rearing habitats in the lower Columbia River (the John Day and Dalles reservoirs and the free-flowing section downstream of Bonneville Dam) as well as in the lower sections of two major tributaries (the John Day and Deschutes rivers). The density of newly emerged drifting larvae was higher in dam tailraces (a mean of 7.7 larvae/100 m3 in surface tows) than in the lower reservoirs (0.3 larvae/100 m3), indicating that tailraces were areas of more intense spawning. Density was particularly high in the Bonneville Dam tailrace (15.1 larvae/100 m3), perhaps because adult northern pikeminnow are abundant below Bonneville Dam and this is the first tailrace and suitable main-stem spawning habitat encountered during upriver spawning migrations. Spawning also occurred in both of the tributaries sampled but not in a backwater. Spawning in the Columbia River primarily took place during the month of June in 1993 and 1994, when the water temperature rose from 14??C to 18??C, but occurred about 2 weeks later in 1995 and 1996, possibly because of cooler June water temperature (14-15??C) in these years. The period of drift was brief (about 1-3 d), with larvae recruiting to shallow, low-velocity shorelines of main-channel and backwater areas to rear. Larvae reared in greatest densities at sites with fine sediment or sand substrates and moderate- to high-density vegetation (a mean density of 92.1 larvae/10 m3). The success of northern pikeminnow in the Columbia River basin may be partly attributable to their ability to locate adequate spawning and rearing conditions in a variety of main-stem and tributary

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

    SciTech Connect

    Porter, Russell .

    2009-09-10

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

  3. Development of a System-Wide Predator Control Program: Stepwise Implementation of a Predation Index, Predator Control Fisheries, and Evaluation Plan in the Columbia River Basin; Northern Pikeminnow Management Program, 2000 Annual Report.

    SciTech Connect

    Porter, Russell G.; Glaser, Bryce G.; Amren, Jennifer

    2003-03-01

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

  4. Development of a System-Wide Predator Control Program: Stepwise Implementation of a Predation Index, Predator Control Fisheries, and Evaluation Plan in the Columbia River Basin; Northern Pikeminnow Management Program, 2002 Annual Report.

    SciTech Connect

    Porter, Russell G.; Winther, Eric C.; Fox, Lyle G.

    2004-01-01

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

  5. Development of a System-wide Predator Control Program: Stepwise Implementation of a Predation Index, Predator Control Fisheries, and Evaluation Plan in the Columbia River Basin; Northern Pikeminnow Management Program, 1998 Annual Report.

    SciTech Connect

    Young, Franklin R.; Wachtel, Mark L.; Petersen, Marc R.

    2003-03-01

    We are reporting on the progress of the Northern Pikeminnow Sport-Reward Fishery (NPSRF) in the lower Columbia and Snake rivers for 1998. The objectives of this project were to (1) implement a sport fishery that rewards anglers who harvest northern pikeminnow Ptychocheilus oregonensis {ge}279 mm (11 inches) total length, (2) collect catch data on selected fish species caught by fishery participants while targeting northern pikeminnow, (3) monitor and report incidental catch of sensitive salmonid species by anglers targeting northern pikeminnow and, (4) collect, monitor and report data on angler participation, catch and catch per angler day of northern pikeminnow during the season. A total of 108,903 northern pikeminnow {ge}279 mm were harvested during the 1998 season and 21,959 angler days were spent harvesting these fish. Harvest was below the seven year average of 150,874 and participation was well below the seven-year average of 51,013 angler days. Catch per angler day for all anglers during the season was 4.96 and exceeded the seven-year average of 2.96 northern pikeminnow per angler day. Peamouth Mylocheilus caurinus, and white sturgeon Acipencer transmontanus, were the other species most often harvested by returning NPSRF anglers targeting northern pikeminnow. Harvest of salmonids Oncorhynchus spp. by NPSRF anglers targeting northern pikeminnow remained below limits established by the National Marine Fisheries Service (NMFS).

  6. Development of a System-Wide Predator Control Program: Stepwise Implementation of a Predation Index, Predator Control Fisheries, and Evaluation Plan in the Columbia River Basin; Northern Pikeminnow Management Program, 2001 Annual Report.

    SciTech Connect

    Porter, Russell G.; Winther, Eric C.; Fox, Lyle G.

    2003-03-01

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

  7. Predation by northern pikeminnow on juvenile salmonids in The Dalles Dam tailrace: field, laboratory, and habitat modeling studies (FY2000)

    USGS Publications Warehouse

    Petersen, James H.; Barfoot, Craig A.; Sheer, Mindi B.

    2001-01-01

    Predation by resident fish is known to be a substantial cause of juvenile salmonid mortality, especially in dam tailraces and outfall locations. Conditions in The Dalles Dam tailrace are unique compared to other projects on the Columbia or Snake rivers, having a complex basin with a series of downriver islands where predators are known to reside. In May-June of 1999, northern pikeminnow and smallmouth bass were sampled in the tailrace of The Dalles Dam during periods immediately following the release of PIT-tagged juvenile salmonids for survival studies. Over twice as many smallmouth bass (N = 101) were collected as northern pikeminnow (N = 40), but none of the predators had PIT tags within their gut. A laboratory study was conducted to estimate the time required for PIT tags in juvenile salmonids to be evacuated from the gut of northern pikeminnow after consuming a tagged preyfish. Evacuation rate was sensitive to temperature, with median evacuation time being 21 h at 18 oC and 30 h at 14 oC. These results suggest that field studies to estimate predator population sizes, feeding rates, or predation on specific release groups would require considerably more effort than we allocated during 1999.

  8. Persistence of identifiable remains of white sturgeon juveniles in digestive tracts of northern pikeminnow

    USGS Publications Warehouse

    Gadomski, D.M.; Frost, C.N.

    2004-01-01

    Juvenile white sturgeon, Acipenser transmontanus, have not been commonly identified as prey items in digestive tracts of fishes collected in the wild. In particular, the diet of northern pikeminnow, Ptychocheilus oregonensis, an abundant Pacific Northwest freshwater predator which has been widely studied, has not included juvenile white sturgeon. To aid in interpreting these results and help in planning future feeding studies, we determined the persistence of identifiable remains of white sturgeon juveniles in this predator's digestive tract. Northern pikeminnow (mean total length = 476 mm), were force-fed meals of 2 or 3 juvenile white sturgeon (mean total length = 91 mm). After digestive periods of 4, 8, 16, 24, 28, and 32h at a water temperature of about 17 ??C, fish were sacrificed, digestive tracts removed, and contents examined. Our results indicate that juvenile white sturgeon would be readily discernable in digestive tracts of northern pikeminnow at least a day after feeding, with scutes remaining undigested and identifiable for 28 h.

  9. Development and corroboration of a bioenergetics model for northern pikeminnow (Ptychocheilus oregonensis) feeding on juvenile salmonids in the Columbia River

    USGS Publications Warehouse

    Petersen, J.H.; Ward, D.L.

    1999-01-01

    A bioenergetics model was developed and corroborated for northern pikeminnow Ptychocheilus oregonensis, an important predator on juvenile salmonids in the Pacific Northwest. Predictions of modeled predation rate on salmonids were compared with field data from three areas of John Day Reservoir (Columbia River). To make bioenergetics model estimates of predation rate, three methods were used to approximate the change in mass of average predators during 30-d growth periods: observed change in mass between the first and the second month, predicted change in mass calculated with seasonal growth rates, and predicted change in mass based on an annual growth model. For all reservoir areas combined, bioenergetics model predictions of predation on salmon were 19% lower than field estimates based on observed masses, 45% lower than estimates based on seasonal growth rates, and 15% lower than estimates based on the annual growth model. For each growth approach, the largest differences in field-versus-model predation occurred at the midreservoir area (-84% to -67% difference). Model predictions of the rate of predation on salmonids were examined for sensitivity to parameter variation, swimming speed, sampling bias caused by gear selectivity, and asymmetric size distributions of predators. The specific daily growth rate of northern pikeminnow predicted by the model was highest in July and October and decreased during August. The bioenergetics model for northern pikeminnow performed well compared with models for other fish species that have been tested with field data. This model should be a useful tool for evaluating management actions such as predator removal, examining the influence of temperature on predation rates, and exploring interactions between predators in the Columbia River basin.

  10. Predation by Northern Pikeminnow and tiger muskellunge on juvenile salmonids in a high–head reservoir: Implications for anadromous fish reintroductions

    USGS Publications Warehouse

    Sorel, Mark H.; Hansen, Adam G.; Connelly, Kristin A.; Wilson, Andrew C.; Lowery, Erin D.; Beauchamp, David A.

    2016-01-01

    The feasibility of reintroducing anadromous salmonids into reservoirs above high-head dams is affected by the suitability of the reservoir habitat for rearing and the interactions of the resident fish with introduced fish. We evaluated the predation risk to anadromous salmonids considered for reintroduction in Merwin Reservoir on the North Fork Lewis River in Washington State for two reservoir use-scenarios: year-round rearing and smolt migration. We characterized the role of the primary predators, Northern Pikeminnow Ptychocheilus oregonensis and tiger muskellunge (Northern Pike Esox lucius × Muskellunge E. masquinongy), by using stable isotopes and stomach content analysis, quantified seasonal, per capita predation using bioenergetics modeling, and evaluated the size and age structures of the populations. We then combined these inputs to estimate predation rates of size-structured population units. Northern Pikeminnow of FL ≥ 300 mm were highly cannibalistic and exhibited modest, seasonal, per capita predation on salmonids, but they were disproportionately much less abundant than smaller, less piscivorous, conspecifics. The annual predation on kokanee Oncorhynchus nerka (in biomass) by a size-structured unit of 1,000 Northern Pikeminnow having a FL ≥ 300 mm was analogous to 16,000–40,000 age-0 spring Chinook Salmon O. tshawytscha rearing year-round, or 400–1,000 age-1 smolts migrating April–June. The per capita consumption of salmonids by Northern Pikeminnow having a FL ≥ 200 mm was relatively low, due in large part to spatial segregation during the summer and the skewed size distribution of the predator population. Tiger muskellunge fed heavily on Northern Pikeminnow, other nonsalmonids, and minimally on salmonids. In addition to cannibalism within the Northern Pikeminnow population, predation by tiger muskellunge likely contributed to the low recruitment of larger (more piscivorous) Northern Pikeminnow, thereby decreasing the risk of predation to

  11. Development of a Systemwide Predator Control Program, Section I : Northern Squawfish Management Program - Implementation, 1997 Annual Report.

    SciTech Connect

    Young, Franklin R.

    1998-10-01

    Report on results from the sixth year of a basin-wide program to harvest northern pikeminnow (Ptychocheilus oregonensis) in an effort to reduce mortality due to northern pikeminnow predation on juvenile salmonids during their emigration from natal streams to the ocean.

  12. Caribbean basin framework, 2: Northern Central America

    SciTech Connect

    Tyburski, S.A.; Gordon, M.B.; Mann, P. )

    1991-03-01

    There are four Jurassic to Recent basin-forming periods in northern Central America (honduras, Honduran Borderlands, Belize, Guatemala, northern Nicaragua): (1) Middle Jurassic-Early Cretaceous rifting and subsidence along normal faults in Honduras and Guatemala; rifts are suggested but are not well defined in Honduras by the distribution of clastic sediments and associated volcanic rocks. Rifting is attributed to the separation of Central America from the southern margin of the North American plate; (2) Cretaceous subsidence recorded by the development of a Cretaceous carbonate platform in Honduras, Guatemala, and Belize; subsidence is attributed to thermal subsidence of the rifted margins of the various blocks; (3) Late Cretaceous-Recent development of a volcanic arc along the western margin of Middle America and the northern margin of Honduras; (4) Late Cretaceous large-scale folding in Honduras, ophiolite obduction, and formation of a foredeep basin in Guatemala (Sepur trough); deformation is attributed to the collision between a north-facing arc in northern Honduras and the Nicaraguan Rise and the passive margin of Guatemala and Belize; and (5) Eocene to Recent strike-slip faulting along the present-day North American-Caribbean plate boundary in Guatemala, northern Honduras, and Belize. Strike-slip faults and basins form a California-type borderlands characterized by elongate basins that appear as half-grabens in profile. Counterclockwise rotation of the central honduras plateau, a thicker and topographically higher-than-average block within the plate boundary zone, is accommodated by rifting or strike-slip faults at its edges.

  13. Megafans of the Northern Kalahari Basin

    NASA Technical Reports Server (NTRS)

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

    2016-01-01

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

  14. Hydrothermal Activity in the Northern Guaymas Basin

    NASA Astrophysics Data System (ADS)

    Berndt, C.; Hensen, C.; Mortera-Gutierrez, C. A.; Sarkar, S.; Geilert, S.; Schmidt, M.; Liebetrau, V.; Kipfer, R.; Scholz, F.; Doll, M.; Muff, S.; Karstens, J.; Böttner, C.; Chi, W. C.; Moser, M.; Behrendt, R.; Fiskal, A.; Evans, T.; Planke, S.; Lizarralde, D.; Lever, M. A.

    2015-12-01

    Rift-related magmatism in the Guaymas Basin, Gulf of California induces hydrothermal activity within the basin sediments. Mobilized fluids migrate to the seafloor where they are emitted into the water column changing ocean chemistry and fuelling chemosynthetic ecosystems. New seismic and geochemical data from the northern rift arm of the Guaymas Basin document the variety of fluid expulsion phenomena from large-scale subsurface sediment mobilization related to contact metamorphosis to focused small-scale structures. The geochemical composition of emitted fluids depends largely on the age of the fluid escape structures with respect to the underlying intrusions. Whereas, old structures are dominated by methane emission, young vent sites are characterized by hot fluids that carry a wide range of minerals in solution. The overall high geothermal gradient within the basin (mainly between 160 and 260 °C/km) leads to a thin gas hydrate stability zone. Thus, deep hydrothermal fluid advection affects the gas hydrate system and makes it more dynamic than in colder sedimentary basins.

  15. Timing of Cenozoic Basin Formation in Northern Sundaland, Southeast Asia

    SciTech Connect

    Liew, K.K. )

    1994-07-01

    The present shorelines of northern Sundaland show preferential northwest-southeast elongation. This trend is parallel for subparallel to major faults and suture in this region. Continental wrench/shear basins developed on the western portion of this region and back-arc basins developed on the western portion of this region and back-arc basins in the rest of the region are also aligned to this trend. Different basin geometries and structural patterns among Cenozoic basins in northern Sundaland indicate different origins and/or timing of basin formation. Wrench faulting has played a significant role in the formation of these Cenozoic basins. The continued collision of the Indian subplate with the Eurasian plate during early Cenozoic has caused a redistribution of stress within this region. Zones of weakness have been reactivated or created with large lateral displacements by these changes, thus initiating the subsidence of these basins. The episodic initiation of Cenozoic basins may have begun as early as Jurassic and continued till Oligocene.

  16. Coal stratigraphy of northern and central Powder River basin

    SciTech Connect

    McLellan, M.W.; Biewick, L.H.; Molina, C.L.; Pierce, F.W.

    1986-08-01

    Reconstructed stratigraphic frameworks contribute to understanding depositional and structural history of Paleocene rocks in the Powder River basin. By correlating Fort Union Formation coal beds from Foster Creek, Montana, 100 mi southward to near Gillette, Wyoming, they reconstructed the framework from Terret up through Anderson coal beds, about 1700 ft of stratigraphic section. This framework comprises intersecting stratigraphic sections showing distribution of thick coal beds and sandstones across the study area. Coal beds from Terret up through Knobloch are thickest in northern Powder River basin. Stratigraphically above in the Cache through Wall section, the coal beds are thickest farther south in Moorhead and northern Spotted Horse coalfields. Otter through Anderson coal beds are thickest still farther south in central Powder River basin. Principal coal beds had been mapped in individual local coal fields and identified by local names. They have correlated the coal beds and connected these stratigraphic sections (framework) with stratigraphic frameworks from the southern Powder River basin to provide an integrated picture of coal deposition. Large coal swamps existed in Fort Union time, first in northern Powder River basin and successively farther southward. Basin margins were tectonically active during the Paleocene. Clastic sedimentation resulting from this tectonism may have created conditions controlling peat deposition. Intermittently, peat deposition was interrupted across large areas by a great influx of clastic sediments. At other times, peat deposits were cut by narrow channels as drainage systems changed course.

  17. Somali Basin, Chain Ridge, and origin of the Northern Somali Basin gravity and geoid low

    NASA Technical Reports Server (NTRS)

    Cochran, James R.

    1988-01-01

    Geophysical data are used to investigate the origin of the Northern Somali Basin and its relationship to surrounding tectonic elements. The results show the Northern Somali Basin to be the third of a series of oceanic basins separated by long transform faults created during movement between East and West Gondwanaland. The flexure resulting from differential subsidence across Chain Ridge along with the difference in lithospheric thermal structure on either side of it can account for the amplitude and shape of the observed geoid step and gravity anomalies across Chain Rige. It is suggested that the geoid and gravity low over the Northern Somali Basin may result from the superposition of a continental edge effect anomaly and the fracture zone edge effect anomaly.

  18. Coal bed methane potential of northern Appalachian basin

    SciTech Connect

    Kelafant, J.; Wicks, D.; Kuuskraa, V.

    1987-09-01

    Coal-bed methane in the northern part of the Appalachian basin represents a significant potential source of natural gas for the northeastern US. The numerous, relatively thick and areally extensive coal beds of attractive rank and depth offer the promise of large, low-cost reserves of natural gas. The proximity of the supply source to northeastern markets and the location of the basin within an established pipeline infrastructure further enhance its economic outlook. Lewin and Associations, Inc., under the sponsorship of the Gas Research Institute and with participation of numerous basin geologists, completed a resource economics study of coal bed methane in the northern part of the Appalachian basin. As part of this study, six major coal seams and groups have been targeted as holding the most potential for containing large volumes of gas: the Brookville-Clarion, Kittanning, Freeport, Pittsburgh, Sewickley, and Waynesburg coals. In addition to these major seams and groups, several less areally extensive coals are economical on a local level, particularly the Brush Creek and Mahoning coals in Pennsylvania. The preliminary estimate of gas in place for the northern part of the Appalachian basin is between 50-100 tcf, with a considerable portion of this resource potentially economic at today's gas prices. The coal seams considered by this resource assessment study are at 12 in. thick and with greater than 400 ft of overburden.

  19. Cryopreservation of Sperm from the Endangered Colorado Pikeminnow

    USGS Publications Warehouse

    Tiersch, T.R.; Figiel, C.R.; Wayman, W.R.; Williamson, J.H.; Gorman, O.T.; Carmichael, G.J.

    2004-01-01

    We developed methods for the cryopreservation of sperm of the endangered Colorado pikeminnow Ptychocheilus lucius. Sperm were collected from a captive broodstock population of Colorado pikeminnow reared and maintained at the Dexter National Fish Hatchery and Technology Center. Our objectives were to (1) evaluate the effects on sperm motility of 24-h storage in Hanks' balanced salt solution (HBSS); (2) characterize sperm motility and duration; (3) examine the relationship between sperm motility and osmotic pressure; (4) examine the effect of four cryoprotectants (dimethyl sulfoxide [DMSO], dimethyl acetamide [DMA], glycerol, and methanol [MeOH] at two concentrations [5% and 10%]) on postthaw motility; and (5) compare the effect of two cooling rates (40??C/ min and 4??C/min) on postthaw motility. The sperm samples diluted with HBSS retained higher motility (mean ??SD, 77 ?? 22%; n = 9) than did undiluted samples (12 ?? 30%; n = 9) after 24 h of storage. When exposed to HBSS at 274 mosmols/kg or more, few sperm became motile (???1%). Exposure to HBSS at 265 mosmols/kg elicited threshold activation (defined as 10% motility), and maximum motility (>95%) was observed at 93 mosmols/ kg. The maximum motility of sperm was observed within 10 s after activation with deionized water, and sperm remained motile for 57 s. The sperm that were cooled at a rate of 40??C/min and cryopreserved with 5% MeOH retained higher postthaw motility (56 ?? 13%) than did sperm cryopreserved with DMSO, DMA, or glycerol (at 5% and 10%). When the sperm samples were cooled at a rate of 4??C/min, sperm cryopreserved with MeOH (5% or 10%) or DMSO (5% or 10%) retained the highest postthaw motilities (???14%). The use of cryopreserved sperm can assist hatchery managers in the production of fish, provide for the long-term conservation of genetic resources, and assist in the recovery of endangered species such as the Colorado pikeminnow.

  20. Potential cretaceous play in the Rharb basin of northern Morocco

    SciTech Connect

    Jobidon, G.P. )

    1993-09-01

    The autochthonous Cretaceous in the Rharb basin of northern Morocco is located underneath a cover of neogene sediments and of the Prerif nappe olistostrome, which was emplaced during the Tortonian 7 m.y. The presence of infranappe Cretaceous sediments is documented in a few onshore wells in the Rharb basin and in the adjacent Prerif Rides area, as well as in the Rif Mountains. Their presence in the deeper portion of the Rharb basin is difficult to detail because of poor seismic resolution data beneath dispersive prerif nappe. A recent study of offshore seismic data acquired by PCIAC in 1987 indicates that the infranappe interval can be more than 1500 m thick in some of the offshore Kenitra area. These sediments have seismic signatures that would correspond to Middle Cretaceous transgressions, culminating with a Turonian highstand. Their deposition systems were located on the northern and western flanks of the Meseta and were followed by a hiatus lasting until the Miocene. Regional studies of gravity and magnetic data provide and additional understanding of the Rif province, its evolution, and the possible presence of autochthonous Cretaceous sediments below the prerif nappe cover. The infranappe of Rharb basin has a good potential to develop into a major hydrocarbon play with the presence of middle Cretaceous reservoir rocks, Turonian-Cenomanian black shale source rocks, as well as the timely combination of trap formation, source rock maturation, and hydrocarbon migration.

  1. Hydrogeologic data for the northern Rocky Mountains intermontane basins, Montana

    USGS Publications Warehouse

    Dutton, DeAnn M.; Lawlor, Sean M.; Briar, D.W.; Tresch, R.E.

    1995-01-01

    The U.S. Geological Survey began a Regional Aquifer- System Analysis of the Northern Rocky Mountains Intermontane Basins of western Montana and central and central and northern Idaho in 1990 to establish a regional framework of information for aquifers in 54 intermontane basins in an area of about 77,500 square miles. Selected hydrogeologic data have been used as part of this analysis to define the hydro- logic systems. Records of 1,376 wells completed in 31 of the 34 intermontane basins in the Montana part of the study area are tabulated in this report. Data consist of location, alttiude of land surface, date well constructed, geologic unit, depth of well, diameter of casing, type of finish, top of open interval, primary use of water, water level, date water level measured, discharge, specific capacity, source of discharge data, type of log available, date water-quality parameters measured, specific conductance, pH, and temperature. Hydrographs for selected wells also are included. Locations of wells and basins are shown on the accompanying plate.

  2. Integrated Watershed Assessment: The Northern River Basins Study

    NASA Astrophysics Data System (ADS)

    Wrona, F. J.; Gummer, W. D.

    2001-05-01

    Begun in 1991 and completed in 1996, the Northern River Basins Study (NRBS) was a \\$12 M initiative established by the governments of Canada, Alberta, and the Northwest Territories to assess the cumulative impacts of development, particularly pulp mill related effluent discharges, on the health of the Peace, Athabasca and Slave river basins. The NRBS was launched in response to concerns expressed by northern residents following the 1991 approval of the Alberta Pacific Pulp Mill in Athabasca. Although initiated by governments, the NRBS was set-up to be `arms-length' and was managed by a 25 member Study Board that represented the many interests in the basins, including industry, environmental groups, aboriginal peoples, health, agriculture, education, municipalities, and the federal, territorial and provincial governments. Overseen by an independent Science Advisory Committee, an integrated research program was designed covering eight scientific components: fate and distribution of contaminants, food chain impacts, nutrients, hydrology/hydraulics and sediment transport, uses of the water resources, drinking water quality, traditional knowledge, and synthesis/modeling. Using a 'weight of evidence' approach with a range of ecological and sociological indicators, cumulative impacts from pulp and paper-related discharges and other point and non-point sources of pollution were determined in relation to the health and contaminant levels of aquatic biota, nutrient and dissolved oxygen-related stress, hydrology and climate related changes, and human health and use of the river basins. Based on this assessment and Study Board deliberations, site-specific and basin-wide scientific and management-related recommendations were made to Ministers regarding regulatory and policy changes, basin management and monitoring options, and future research. The Study reinforces the importance of conducting ecosystem-based , interdisciplinary science and the need for public involvement in

  3. Tectonosedimentary history of the sedimentary basins in northern west Siberia

    SciTech Connect

    Kunin, N.Ya.; Segalovich, I.E. )

    1993-09-01

    Sedimentary basins of northern west Siberia belong to the Arctic tectonosedimentary province. This basin evolved dissimilarly compared to those in the Urengoy and more southern areas, which resulted in substantial differences in the geologic characteristics. Seismic surveys indicate that the basement surface in northern west Siberia occurs at great depths, in places exceeding 15 km. The depressions of the basement surfaces are filled with the thick Paleozoic and Mesozoic sequences. The paper discussed the results of seismostratigraphic analysis of more than 13,000 km of regional common-depth-point profiles. These profiles identified systems of east-west-trending and isometric structures in the region. Some of the structures are buried; others are mapped in the upper horizons of the sedimentary cover and decrease in magnitude with depth. Cretaceous marine sediments that were deposited under deep-water conditions and did not compensate for the tectonic subsidence are widely present in the region. Noncompensated sedimentation was the longest from the Late Jurassic to the Hauterivian-Barremian on the Gydan peninsula and in adjacent areas. The Jurassic section is dominate by ingressive marine sediments. Sediments that did not compensate for tectonic subsidence widely occurred in the Early Jurassic and resulted in deposition of petroleum source rocks. Triassic and Jurassic strata occur conformable in most of northern west Siberia. Significant deformation of the Triassic sediments are identified in the periphery of the Triassic marine basin. This indicates that surrounding structures were thrust against northern west Siberia at the Triassic and Jurassic time boundary. Isometric structures of high magnitude were formed during the Paleozoic structure stage and these structures continued to grow through the Triassic and Jurassic. These and other results of seismostratigraphic analysis suggest the high oil potential of the region.

  4. New interpretation of Clarks Fork field, northern Bighorn basin, Montana

    SciTech Connect

    Johnson, J.S.; Lindsley-Griffin, N.

    1986-08-01

    Clarks Fork field is located at the northern edge of the Bighorn basin (T9S, R22E) in Carbon County, Montana. Production was first established in 1944 by General Petroleum Corporation in the Cretaceous Peay Sandstone (basal Frontier) and was later extended to the Cretaceous Greybull (1949) and Lakota (1956) sandstones by British American. Total cumulative hydrocarbons from this field are 1,1789,193 bbl of oil and 3,061,522 mcf of gas, with Lakota sandstones being most productive. Lakota production occurs from a structural-stratigraphic trap in an east-west-trending channel on the axis of Clarks Fork anticline, geographically near the center of the township. Our structural reinterpretation of Clarks Fork field suggests that Elk Basin anticline is a northwest extension of the Elk Basin field anticline. The Elk Basin thrust truncates the north limb of the fold and does not strike to the northwest, as shown by earlier interpretations. They interpret a northwest-striking thrust in the center of the township as a splay off the Elk Basin thrust, and have named it the Clarks Fork thrust. The Clarks Fork anticline is located on the hanging wall of Clarks Fork thrust. Subsurface maps indicate the Clarks Fork area has not been fully developed. Stratigraphic traps in the Lakota and Greybull sandstones are present in several areas of the township. Structural traps in the center and northwest portions of the township may also exist.

  5. Geoenvironmental Investigations of the Humboldt River Basin, Northern Nevada

    USGS Publications Warehouse

    Stillings, Lisa L.

    2003-01-01

    Northern Nevada is one of the world's foremost regions of gold production. The Humboldt River Basin (HRB) covers 43,500 km2 in northern Nevada (Crompton, 1995), and it is home to approximately 18 active gold and silver mines (Driesner and Coyner, 2001) among at least 55 significant metallic mineral deposits (Long and others, 1998). Many of the gold mines are along the Carlin trend in the east-central portion of the HRB, and together they have produced 50 million ounces of gold from 1962 (when the Carlin mine first opened) through April 2002 (Nevada Mining Association, 2002). Mining is not new to the region, however. Beginning in 1849, mining has taken place in numerous districts that cover 39 percent of the land area in the HRB (Tingley, 1998). In addition to gold and silver, As, Ba, Cu, Fe, Hg, Li, Mn, Mo, Pb, S, Sb, V, W, Zn, and industrial commodities such as barite, limestone, fluorite, sand and gravel, gypsum, gemstones, pumice, zeolites, and building stone, have been extracted from the HRB (McFaul and others, 2000). All papers within this series of investigations can be found as lettered chapters of USGS Bulletin 2210, Geoenvironmental Investigations of the Humboldt River Basin, Northern Nevada. Each chapter is available separately online. The data and software utilized in this product (Chapter F) permit the user to view and analyze the geographic relationships among chemistry of stream sediments and surface waters, geology, and various cartographic base information such as but not limited to cities, county boundaries, and land ownership. Data for this product were compiled and or produced as part of a mineral and environmental assessment of the Humboldt River basin conducted by the U.S. Geological Survey between 1995 - 2000.

  6. Wrench fault tectonics in northern New Guinea basin, Papua New Guinea

    SciTech Connect

    Trumbly, N.I.; Pigott, J.D.

    1984-04-01

    New Guinea lies on the northern Australian plate boundary and has been a sensitive tectonic recorder of Cenozoic plate interactions between the Australian and Pacific plates. The specific plate interactions are documented by the evolution of the Northern New Guinea fault system and the basin it overprints, the Northern New Guinea basin. Consideration of plate kinematics suggests convergence became increasingly oblique during the Cenozoic. Hydrocarbon exploration strategies within the Northern New Guinea basin must address not only sedimentation, but also must deal with the basin's complex structural and tectonic evolution. A static tectonic classification will not adequately define the Northern New Guinea basin. It is better described as an evolving basin being overprinted by wrenching.

  7. Geothermal resources of the northern gulf of Mexico basin

    USGS Publications Warehouse

    Jones, P.H.

    1970-01-01

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

  8. Unusual Radar Backscatter along the Northern Rim of Imbrium Basin

    NASA Technical Reports Server (NTRS)

    Thompson, Thomas W.; Campbell, Bruce A.; Ghent, Rebecca R.; Hawke, B. Ray; Leverington, David W.

    2006-01-01

    A viewgraph presentation of the unusual radar backscatter properties along the Northern Rim of Imbrium Basin is shown. The contents include: 1) Visual and Infrared Observations of Moon; 2) Radar Observations of Moon; 3) Lunar Orbiter Photographs Geologic Setting; 4) 70-cm Radar Data; 5) .70-cm Radar Dark Halo Craters; 6) 3.8-cm Radar Data; 7) 7.5-m Radar Data; 8) 70cm, 3.8 cm and 7.5-m Radar Data; 9) Optical and Infrared Data; 10) Plato Rilles; 11) Isopachs of Crater Ejecta; 12) Plato-like Craters; 13) Observation Summary; 14) Interpretation Matrix; 15) Dark Halo Diameters vs. Crater Size; and 16) Radar Geologic Column.

  9. Regional groundwater flow modeling of the Geba basin, northern Ethiopia

    NASA Astrophysics Data System (ADS)

    Gebreyohannes, Tesfamichael; De Smedt, Florimond; Walraevens, Kristine; Gebresilassie, Solomon; Hussien, Abdelwassie; Hagos, Miruts; Amare, Kassa; Deckers, Jozef; Gebrehiwot, Kindeya

    2017-01-01

    The Geba basin is one of the most food-insecure areas of the Tigray regional state in northern Ethiopia due to recurrent drought resulting from erratic distribution of rainfall. Since the beginning of the 1990s, rain-fed agriculture has been supported through small-scale irrigation schemes mainly by surface-water harvesting, but success has been limited. Hence, use of groundwater for irrigation purposes has gained considerable attention. The main purpose of this study is to assess groundwater resources in the Geba basin by means of a MODFLOW modeling approach. The model is calibrated using observed groundwater levels, yielding a clear insight into the groundwater flow systems and reserves. Results show that none of the hydrogeological formations can be considered as aquifers that can be exploited for large-scale groundwater exploitation. However, aquitards can be identified that can support small-scale groundwater abstraction for irrigation needs in regions that are either designated as groundwater discharge areas or where groundwater levels are shallow and can be tapped by hand-dug wells or shallow boreholes.

  10. Pulsed basin development on northern margin of South China Sea

    SciTech Connect

    Ru, K.; Pigott, J.D.

    1987-05-01

    Detailed analysis of the geothermal gradients, structural architecture, genetic stratigraphy, and subsidence rate history of the sedimentary basins on the northern margin of the South China Sea (NMSC) reveal three temporally distinct but regionally correlative tectonic extensional episodes. The timing of these pulsed episodes of basin development are: Episode One, Late Cretaceous to Paleocene; Episode Two, late Eocene to early Oligocene; and Episode Three, middle Miocene. Each initiating episode on the NMSC is characterized by an ephemeral (< 10 m.y.) increase in heat flow (> 3 HFU), formation of regionally en echelon grabens or half-grabens, ensuing transgression, and high subsidence rate (> 50 m/m.y.). Trends of basin boundaries and major fault trends evolved from predominantly northeast for Episode One, to northeast and east-west for Episode Two, and to northwest and east-west and for Episode Three. Tectonically, the northeast and east-west trends resulted primarily from rifting along northwest and north-south extensional directions, respectively. The orientation, sense of displacement and time of activation of the Red River fault, Vietnam fracture zone, and the northeast-east-west and northwest-east-west multiple sets of fractures may be explained as responses to episodic changes in the regional stress field utilizing the guidance of inherited zones of crustal weakness. The timing and extent of the hydrocarbon maturation, reservoir development, and stratigraphic-structural closure in the NMSC were directly affected by this pulsed tectonic activity. Therefore, exploration strategies based purely upon the NMSC being a passive rifted margin are both inappropriate and misleading.

  11. Regional Fluid Flow and Basin Modeling in Northern Alaska

    USGS Publications Warehouse

    Kelley, Karen D.

    2007-01-01

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

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

    PubMed

    Wu, Ya; Wang, Yanxin

    2014-05-01

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

  13. Application Of A Dynamic Model to Assess Geomorphic and Hydrologic Controls on Age-0 Colorado Pikeminnow Distribution in the Green River, Colorado And Utah

    NASA Astrophysics Data System (ADS)

    Schmidt, J. C.

    2005-05-01

    Analysis of field data and development and application of a dynamic model indicate that water releases from Flaming Gorge Dam have a large potential effect on larval drift and distribution of age-0 Colorado pikeminnow (Ptychocheilus lucius) in the middle Green River. The model predicts that high releases at the time of drift greatly increase the proportion of the population transported beyond the study area to unfavorable river environments. The model also predicts that channel simplification caused by flow regulation results in a more even longitudinal distribution of larval fish habitat. Colorado pikeminnow are a federally endangered species endemic to the Colorado River basin that utilize backwaters during their larval stage. The present agency-mandated field-sampling program for backwater habitats is probably inadequate, because it takes place at a time when the model predicts that most larval fish have drifted beyond the study area. Development of the model shows that the role of the geomorphic and hydraulic attributes that control larval drift and transport into backwaters, and that were parameterized in the model, are not well known.

  14. Base of fresh ground water, northern Louisiana Salt-Dome Basin and vicinity, northern Louisiana and southern Arkansas

    USGS Publications Warehouse

    Ryals, G.N.

    1980-01-01

    The National Waste Terminal Storage Program is an effort by the U.S. Department of Energy to locate and develop sites for disposal or storage of commercially produced radioactive wastes. As part of this program, salt domes in the northern Louisiana salt-dome basin are being studied to determine their suitability as repositories. Part of the U.S. Geological Survey 's participation in the program has been to describe the regional geohydrology of the northern Louisiana salt-dome basin. A map based on a compilation of published data and the interpretation of electrical logs shows the altitude of the base of freshwater in aquifers in the northern Louisiana salt-dome basin. (USGS)

  15. The central and northern Appalachian Basin-a frontier region for coalbed methane development

    USGS Publications Warehouse

    Lyons, P.C.

    1998-01-01

    The Appalachian basin is the world's second largest coalbed-methane (CBM) producing basin. It has nearly 4000 wells with 1996 annual production at 147.8 billion cubic feet (Bcf). Cumulative CBM production is close to 0.9 trillion cubic feet (Tcf). The Black Warrior Basin of Alabama in the southern Appalachian basin (including a very minor amount from the Cahaba coal field) accounts for about 75% of this annual production and about 75% of the wells, and the remainder comes from the central and northern Appalachian basin. The Southwest Virginia coal field accounts for about 95% of the production from the central and northern parts of the Appalachian basin. Production data and trends imply that several of the Appalachian basin states, except for Alabama and Virginia, are in their infancy with respect to CBM development. Total in-place CBM resources in the central and northern Appalachian basin have been variously estimated at 66 to 76 trillion cubic feet (Tcf), of which an estimated 14.55 Tcf (~ 20%) is technically recoverable according to a 1995 U.S. Geological Survey assessment. For comparison in the Black Warrior basin of the 20 Tcf in-place CBM resources, 2.30 Tcf (~ 12%) is technically recoverable. Because close to 0.9 Tcf of CBM has already been produced from the Black Warrior basin and the proved reserves are about 0.8 Tcf for 1996 [Energy Information Administration (EIA), 1997]. U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves, 1996 Annual Report. U.S. Department of Energy DOE/EIA-0216(96), 145 pp.], these data imply that the central and northern Appalachian basin could become increasingly important in the Appalachian basin CBM picture as CBM resources are depleted in the southern Appalachian basin (Black Warrior Basin and Cahaba Coal Field). CBM development in the Appalachian states could decrease the eastern U.S.A.'s dependence on coal for electricity. CBM is expected to provide over the next few decades a virtually untapped source of

  16. Inversion tectonics in the Neogene basins of Tuscany (Northern Apennines, Italy): Insights from the Pisa-Viareggio basin.

    NASA Astrophysics Data System (ADS)

    Argnani, A.; Rogledi, S.

    2012-04-01

    Several sedimentary basins are located in the internal portion of the Northern Apennines, bordering the eastern side of the Northern Tyrrhenian sea. These basins trend almost parallel to the Apennine range and are filled by Neogene sediments with thickness ranging between few 100's m to few km (Martini et al., 2001). Sediments belonging to these basins crop out extensively in western Tuscany, often appearing heavily deformed. Although classically interpreted as extensional basins (e.g., Martini and Sagri, 1993 and references therein), some papers call for an initial thrust-related origin (Finetti et al., 2001; Bonini and Sani, 2002), and the long-lasting debate about the origin of the Neogene basins of Tuscany is still ongoing (cfr. Brogi 2011 and Sani et al., 2004). This contribution aims at presenting the case of the Pisa-Viareggio basin, which is the northernmost one among the large basins of Tuscany (Pascucci et al., 2007). This basin straddles the coastline and has been investigated through the interpretation of a grid of industrial seismic profiles covering the Pisa plain and tied to exploration wells. In the Pisa-Viareggio basin seismic profiles show a west-dipping listric extensional fault that bounds the basin to the east, supporting an extensional origin. The basin is filled with up to 3 seconds of upper Messinian to Quaternary sediments, and extension mostly occurred during late Messinian-early Pliocene, although continuing with reduced intensity till the Quaternary. The southern part of this basin shows a superimposed contractional deformation (tectonic inversion), that progressively increases to the south, where the basin appears completely overturned and eroded in the Livorno Mountains. The basin-boundary fault trends roughly NNW-SSE and is buried in the Quaternary sediments of the Pisa plain, but it turns rather abruptly to N-S and NNE-SSW in the south, near Livorno. Inspection of detailed geological maps (Lazzarotto et al., 1990) suggests that the

  17. Uplift and Erosion in the Northern Al Kufrah Basin (Southeast Libya)

    NASA Astrophysics Data System (ADS)

    Gröger, H. R.; Bjørnseth, H. M.; Higgins, S.; Vandré, C.; Walderhaug, O.; Geiger, M.

    2009-04-01

    The Al Kufrah Basin forms part of the North African continental basin system. While neighbouring basins (e.g. Murzuq Basin, Sirt Basin) are proven petroleum provinces, the Al Kufrah Basin is still in an early stage of exploration. This study combines outcrop studies from the northern basin margin (Jabal Az Zalmah) and the eastern basin margin (Jabal Azbah) with subsurface data in a regional analysis of the key episodes of uplift and erosion in the Al Kufrah Basin. The understanding of the burial and exhumation history of a sedimentary basin is an important parameter for modelling source rock maturation and contributes thus to the evaluation of the hydrocarbon potential. In a first approach the amount of net erosion is estimated using geometrical reconstructions along two perpendicular cross-sections, based on interpretation of 2D-seimic data. In a second step the resulting net erosion map is integrated with three different analytical methods: (1) Shale compaction analyses (based on outcrop samples and well logs), (2) sandstone diagenesis analyses (based on outcrop samples) and (3) apatite fission track analyses (based on outcrop samples). Several erosional events are documented in the Palaeozoic stratigraphic record of the Al Kufrah Basin. The major episodes of regional Palaeozoic uplift and erosion occurred in Late Silurian - Early Devonian and in Late Carboniferous - Early Permian ("Hercynian event"). For both episodes a general southward increase in uplift and erosion has been estimated from integrated analyses of seismic and outcrop data. The northern flank of the basin including the Jabal Az Zalmah outcrop area does not appear to have been subjected to major uplift and erosion during these two Palaeozoic events. Maximum burial was reached during the Mesozoic after deposition of Late Permian - Early Cretaceous (?) continental sandstones. The most important episode of uplift and erosion occurred after the Early Cretaceous (?) sedimentation, leading to net

  18. Reappraisal of the relationship between the northern Nevada rift and Miocene extension in the northern Basin and Range Province

    USGS Publications Warehouse

    Colgan, Joseph P.

    2013-01-01

    The northern Nevada rift is a prominent mafic dike swarm and magnetic anomaly in north-central Nevada inferred to record the Middle Miocene (16.5-15.0 Ma) extension direction in the northern Basin and Range province in the western United States. From the 245°-250° rift direction, Basin and Range extension is inferred to have shifted 45° clockwise to a modern direction of 290°-300° during the late Miocene. The region surrounding the northern Nevada rift was actively extending while the rift formed, and these domains are all characterized by extension oriented 280°-300°. This direction is distinctly different from the rift direction and nearly identical to the modern Basin and Range direction. Although the rate, structural style, and distribution of Basin and Range extension appear to have undergone a significant change in the late Miocene (ca. 10 Ma), the overall spreading direction does not. Middle Miocene extension was directed perpendicular to the axis of the thickest crust formed during Mesozoic shortening and this orientation may reflect gravitational collapse of this thick crust. Orientation of northern Nevada rift dikes may reflect a short-lived regional stress field related to the onset of Yellowstone hotspot volcanism.

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  1. Regional surficial geochemistry of the northern Great Basin

    USGS Publications Warehouse

    Ludington, S.; Folger, H.; Kotlyar, B.; Mossotti, V.G.; Coombs, M.J.; Hildenbrand, T.G.

    2006-01-01

    The regional distribution of arsenic and 20 other elements in stream-sediment samples in northern Nevada and southeastern Oregon was studied in order to gain new insights about the geologic framework and patterns of hydrothermal mineralization in the area. Data were used from 10,261 samples that were originally collected during the National Uranium Resource Evaluation (NURE) Hydrogeochemical and Stream Sediment Reconnaissance (HSSR) program in the 1970s. The data are available as U.S. Geological Survey Open-File Report 02-0227. The data were analyzed using traditional dot maps and interpolation between data points to construct high-resolution raster images, which were correlated with geographic and geologic information using a geographic information system (GIS). Wavelength filters were also used to deconvolute the geochemical images into various textural components, in order to study features with dimensions of a few kilometers to dimensions of hundreds of kilometers. The distribution of arsenic, antimony, gold, and silver is different from distributions of the other elements in that they show a distinctive high background in the southeast part of the area, generally in areas underlain by the pre-Mesozoic craton. Arsenic is an extremely mobile element and can be used to delineate structures that served as conduits for the circulation of metal-bearing fluids. It was used to delineate large crustal structures and is particularly good for delineation of the Battle Mountain-Eureka mineral trend and the Steens lineament, which corresponds to a post-Miocene fault zone. Arsenic distribution patterns also delineated the Black Rock structural boundary, northwest of which the basement apparently consists entirely of Miocene and younger crust. Arsenic is also useful to locate district-sized hydrothermal systems an d clusters of systems. Most important types of hydrothermal mineral deposit in the northern Great Basin appear to be strongly associated with arsenic; this is less

  2. A Wintertime Aerosol Model for the Ganga Basin, Northern India

    NASA Astrophysics Data System (ADS)

    Dey, S.; Tripathi, S. N.

    2006-05-01

    An aerosol model has been developed using mass size distributions of various chemical components measured at Kanpur (an urban location in the Ganga basin, GB, in Northern India) and applied to estimate the radiative effects of the aerosols over the entire GB during the winter season for the first time. The number size distribution of various species was derived from the measured mass concentration and the optical properties were calculated using OPAC model. The anthropogenic contribution to the total extinction was found to be more than 90%. The relative contribution of various species to the aerosol optical depth (AOD) at 0.5 μm are in the following order, (NH2)2SO4 (AS, 37%), nitrate (N, 28%), other salts (S, mainly NaCl and KCl, 19%), dust (9%) and black carbon, BC (7%). Contribution of AS, N, S to the observed AOD decreases with wavelength and that of dust increases with wavelength, whereas, BC contribution remains almost same. The extinction coefficient strongly depends on the relative humidity (RH), as the scattering by fine mode fraction (contributing 88% to the total extinction) is enhanced at high ambient RH. The spectral variation of absorption coefficient indicates that the most likely source of BC (as BC is the dominant absorbing species) in this region is fossil- fuel. The spectral variation of single scattering albedo (SSA) in the fine and coarse mode fractions and that of asymmetry parameter suggests that the internal mixing is more likely scenario, although the possibility of external mixing can not be ruled out. If the RH is lowered by ~20%, BC contribution to the AOD increases by ~3.5%, which implies that the RH is a strong controlling factor of the aerosol forcing. The mean shortwave clear sky top of the atmosphere (TOA) and surface forcing over Kanpur are -13±3 and -43±8 W m-2. Extending the TOA and surface efficiency over the entire GB, the mean TOA and surface forcing become -9±3 and -25±10 W m-2. This results in high atmospheric

  3. Tectonic subsidence of the Zhu 1 Sub-basin in the Pearl River Mouth Basin, northern South China Sea

    NASA Astrophysics Data System (ADS)

    Tang, Xiaoyin; Yang, Shuchun; Zhu, Junzhang; Long, Zulie; Jiang, Guangzheng; Huang, Shaopeng; Hu, Shengbiao

    2017-01-01

    The Pearl River Mouth Basin, which is situated on the northern margin of the South China Sea, has attracted great attention not only because of its tectonic setting but also because of its abundant hydrocarbon resources. We have analyzed the Cenozoic tectonic subsidence history of 4 drilled wells and 43 artificial wells from the Zhu 1 Sub-basin of the Pearl River Mouth Basin by back-stripping, using newly interpreted seismic profiles. We also calculated the average tectonic sub-sidence rates of the four sags in the Zhu 1 Sub-basin. The rifting and post-rifting stages are separated by abrupt changes in the tectonic subsidence curves and average subsidence rates. In the eastern sags of the Zhu 1 Sub-basin, tectonic subsidence started to slow at ca. 30 Ma, compared with ca. 23.8 Ma in the western sags. This probably corresponds to the timing of break-up and suggests that rifting in the Pearl River Mouth Basin ended earlier in the eastern sags than in the western sags. Anomalously accelerated tectonic subsidence occurred at 17.5-16.4 Ma during the post-rifting stage, with average subsidence rates as high as 301.9 m/Myr. This distinguishes the Pearl River Mouth Basin from classical Atlantic passive continental marginal basins, which demonstrate exponentially decaying post-rift tectonic subsidence.

  4. The Bowser and Sustut Basins, Northern British Columbia, Canada: Insights From Analysis of Magnetic Anomaly Data.

    NASA Astrophysics Data System (ADS)

    Baker, J.; Lowe, C.

    2005-12-01

    The Bowser and Sustut basins occupy an area of more than 60,000 km2 in northern British Columbia, Canada. They comprise three, dominantly sedimentary, stratigraphic successions, in part overlapping in age: the Bowser Lake Group, the Skeena Group, and the Sustut Group. These three successions overlie arc volcanic and volcaniclastic strata of Stikinia, an allochtonous island arc terrane that accreted to the western margin of North America in the Early Jurassic to early Middle Jurassic. All three basin successions and underlying Stikinia were deformed during development of a thin-skinned fold and thrust belt (the Skeena Fold and Thrust Belt) in Cretaceous and possibly into earliest Tertiary time. Recently, the basins have been the focus of intense geological studies which have resulted in major revisions to the stratigraphic and structural framework of the basins and demonstrated that they have significantly higher petroleum potential than had been previously recognized. To advance these new findings further requires better imaging of the three-dimensional geometry and architecture of the basins. In this study we harness existing magnetic anomaly data to provide the first quantitative estimates of sedimentary thickness across the entire extents of both basins. Our results, which are in general in accord with geological interpretations, indicate that basin-fill is relatively thin and fairly uniform in the Sustut Basin (2.5-3 km), but highly variable in the Bowser Basin, ranging from less than 2 km to more than 6 km. Overall, sedimentary fill is thicker in the northern half of Bowser Basin compared to the south and is typically less than 2 km near the basins northern, western and southern margins. In addition, we demonstrate how a large, buried intrusion beneath the northeast part of Bowser Basin can account for an observed magnetic anomaly and explain the high coalification gradients and localized high maturation levels of the overlying sedimentary rocks. Neither of

  5. Geochemical data for Jurassic diabase and basalt of the northern Culpeper basin, Virginia

    SciTech Connect

    Lee, K.Y.; Leavy, B.D.; Gottfried, D.

    1983-01-01

    The Culpeper basin is a north-northeast-trending faulted trough at the inner margin of the Piedmont geologic province along the east front of the Blue Ridge. Most of the Culpeper Group is intruded and locally metamorphosed by dikes, sills, and stocks of tholeiitic diabase. This report deals with a suite of samples from several diabase intrusives and basalt flows in the northern part of the Culpeper basin in Virginia. 22 refs., 2 figs., 2 tabs. (ACR)

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  7. CONTROL OF MEDUSAHEAD WITH IMAZAPIC AND PRESCRIBED BURNING IN THE NORTHERN GREAT BASIN

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Medusahead (Taeniatherum caput-medusae (L.) Nevski) is an invasive, exotic annual grass that is reducing the productivity and biodiversity of rangelands. Efforts to control medusahead on rangeland in the northern Great Basin are rarely successful. We evaluated the effectiveness of six treatments o...

  8. Ecological Condition of Streams in Northern Nevada EPA R-MAP Humboldt Basin Project

    EPA Science Inventory

    This report presents stream data on the Humboldt River Basin in northern Nevada using the R-EMAP Program. Water is of primary importance to both the economy and the ecology of the region. Many of the waters of Nevada have previously received relatively little attention in regar...

  9. The northern Great Basin: a region of continual change

    Technology Transfer Automated Retrieval System (TEKTRAN)

    There are many controversies and conflicts surrounding land management in the Great Basin. The conflicts often revolve around the maintenance of native plant and animal communities. This paper outlines some of the historical aspects of plant community change and some of the unanticipated impacts of ...

  10. Assessment of coal geology, resources, and reserves in the northern Wyoming Powder River Basin

    USGS Publications Warehouse

    Scott, David C.; Haacke, Jon E.; Osmonson, Lee M.; Luppens, James A.; Pierce, Paul E.; Rohrbacher, Timothy J.

    2010-01-01

    The abundance of new borehole data from recent coal bed natural gas development in the Powder River Basin was utilized by the U.S. Geological Survey for the most comprehensive evaluation to date of coal resources and reserves in the Northern Wyoming Powder River Basin assessment area. It is the second area within the Powder River Basin to be assessed as part of a regional coal assessment program; the first was an evaluation of coal resources and reserves in the Gillette coal field, adjacent to and south of the Northern Wyoming Powder River Basin assessment area. There are no active coal mines in the Northern Wyoming Powder River Basin assessment area at present. However, more than 100 million short tons of coal were produced from the Sheridan coal field between the years 1887 and 2000, which represents most of the coal production within the northwestern part of the Northern Wyoming Powder River Basin assessment area. A total of 33 coal beds were identified during the present study, 24 of which were modeled and evaluated to determine in-place coal resources. Given current technology, economic factors, and restrictions to mining, seven of the beds were evaluated for potential reserves. The restrictions included railroads, a Federal interstate highway, urban areas, and alluvial valley floors. Other restrictions, such as depth, thickness of coal beds, mined-out areas, and areas of burned coal, were also considered. The total original coal resource in the Northern Wyoming Powder River Basin assessment area for all 24 coal beds assessed, with no restrictions applied, was calculated to be 285 billion short tons. Available coal resources, which are part of the original coal resource that is accessible for potential mine development after subtracting all restrictions, are about 263 billion short tons (92.3 percent of the original coal resource). Recoverable coal, which is that portion of available coal remaining after subtracting mining and processing losses, was determined

  11. Implications for the formation of the Hollywood Basin from gravity interpretations of the northern Los Angeles Basin, California

    USGS Publications Warehouse

    Hildenbrand, Thomas G.; Davidson, Jeffrey G.; Ponti, Daniel J.; Langenheim, V.E.

    2001-01-01

    Gravity data provide insights on the complex tectonic history and structural development of the northern Los Angeles Basin region. The Hollywood basin appears to be a long (> 12 km), narrow (up to 2 km wide) trough lying between the Santa Monica Mountains and the Wilshire arch. In the deepest parts of the Hollywood basin, the modeled average thickness ranges from roughly 250 m if filled with only Quaternary sediments to approximately 600 m if Pliocene sediments are also present. Interpretations of conflicting drill hole data force us to consider both these scenarios. Because of the marked density contrast between the dense Santa Monica Mountains and the low-density sediments in the Los Angeles Basin, the gravity method is particularly useful in mapping the maximum displacement along the Santa Monica-Hollywood-Raymond fault zone. The gravity-defined Santa Monica–Hollywood fault zone deviates, in places, from the mapped active fault and fold scarps located with boreholes and trenching and by geomorphological mapping by Dolan and others (1997). Our models suggest that the Santa Monica–Hollywood fault zone dips northward approximately 63°. Three structural models are considered for the origin of the Hollywood basin: pull-apart basin, flexural basin, and a basin related to a back limb of a major fold. Although our preferred structural model involves flexure, the available geologic and geophysical data do not preclude contributions to the deepening of the basin from one or both of the other two models. Of particular interest is that the distribution of red-tagged buildings and structures damaged by the Northridge earthquake has a strong spatial correlation with the axis of the Hollywood basin defined by the gravity data. Several explanations for this correlation are explored, but two preferred geologic factors for the amplification of ground motion besides local site effects are (1) focussing of energy by a fault along the axis of the Hollywood basin and (2

  12. Comparison of geoelectric and seismic reflection models of the Zambezi Valley basins, northern Zimbabwe

    NASA Astrophysics Data System (ADS)

    Bailey, David; Whaler, Kathy; Zengeni, Teddy

    2000-09-01

    The Mana Pools and Lower Zambezi Karoo sedimentary basins lie within the Zambezi mobile belt in northern Zimbabwe. The subsurface apparent resistivities measured at both locations are extremely low. Magnetotelluric (MT) data along a profile across part of the Lower Zambezi basin have been inverted using Rapid Relaxation Inversion (Smith & Booker 1991) to find the minimum structure needed to fit the data and compare with an earlier forward model. The resistivity models of both the Mana Pools and the Lower Zambezi basins are then compared with their structure revealed from seismic reflection data. The resistivity structure of the Mana Pools basin is well modelled as a series of different resistivity layers whose boundaries are defined by the seismic data. However, the resistivity structure of the Lower Zambezi basin cannot be matched easily to the seismic structure; additional structure with no seismic expression is required. There is a conductive feature in the two basins in the Upper Karoo sandstone layer that extends below the seismic basement beneath the Lower Zambezi basin. This indicates that the conductors may represent different types of features in the two basins, consistent with their proposed different tectonic origins. A resistive unit is present within the sediments in the Lower Zambezi basin that may represent intercalated basalt dykes, giving an anisotropic MT response. It has been suggested that there might be similar thin basalt layers within the sediments of the Mana Pools basin, but these could not be resolved by MT methods. The low resistivity of the basement, particularly beneath the Lower Zambezi basin, is remarkable and may result from a high degree of either chemical or tectonic alteration to the underlying rocks due to metamorphic processes and tectonic disruption during rift formation. The presence of the Lower Zambezi basin conductor at depths greater than the seismic basement is consistent with observations to the west, in the adjacent

  13. Structure of the lithosphere and Mesozoic sedimentary basins in western Liaoning, northern Liaoning, and Songliao, northeast China

    SciTech Connect

    Xu, M.; Middleton, M.F.; Xue, L.F.; Wang, D.P.

    2000-03-01

    The western Liaoning, northern Liaoning, and Songliao areas represent three different tectonic units with different lithosphere thermal-mechanical properties in terms of composition, thickness of the thermal lithosphere, effective elastic thickness, depth of the detachment surface, and strength of the lithosphere. Western Liaoning is characterized by a thick lithosphere with high rigidity and strength, whereas Songliao and northern Liaoning are characterized by relatively thin lithosphere with low rigidity and strength. These differences controlled the development of distinct types of basins under an extensional regime during the Early Cretaceous. The basins in western Liaoning are controlled by faulting rather than by thermal subsidence. The Songliao basin in controlled both by faulting and by thermal subsidence, and thus both syn- and post-rift sequences developed with the same thickness in the center of the basin. In contrast, in northern Liaoning, the basins are mainly controlled by faulting, and to a lesser extent by subsequent thermal subsidence. As a part of east China, where more than 93% of the proven oil reserves of China are distributed, the western Liaoning-northern Liaoning-Songliao area also has attracted considerable attention for this hydrocarbon potential. The Songliao basin is proven to be the largest non-marine petroliferous basin and one of the most important oil- and gas-producing basins in China. In addition, the Tieling-Changtu basin and the Zhezhong depression in northern Liaoning show some petroleum potential. In contrast, basins in western Liaoning represent a limited prospect for oil and gas.

  14. War and early state formation in the northern Titicaca Basin, Peru

    PubMed Central

    Stanish, Charles; Levine, Abigail

    2011-01-01

    Excavations at the site of Taraco in the northern Titicaca Basin of southern Peru indicate a 2,600-y sequence of human occupation beginning ca. 1100 B.C.E. Previous research has identified several political centers in the region in the latter part of the first millennium B.C.E. The two largest centers were Taraco, located near the northern lake edge, and Pukara, located 50 km to the northwest in the grassland pampas. Our data reveal that a high-status residential section of Taraco was burned in the first century A.D., after which economic activity in the area dramatically declined. Coincident with this massive fire at Taraco, Pukara adopted many of the characteristics of state societies and emerged as an expanding regional polity. We conclude that organized conflict, beginning approximately 500 B.C.E., is a significant factor in the evolution of the archaic state in the northern Titicaca Basin. PMID:21788514

  15. War and early state formation in the northern Titicaca Basin, Peru.

    PubMed

    Stanish, Charles; Levine, Abigail

    2011-08-23

    Excavations at the site of Taraco in the northern Titicaca Basin of southern Peru indicate a 2,600-y sequence of human occupation beginning ca. 1100 B.C.E. Previous research has identified several political centers in the region in the latter part of the first millennium B.C.E. The two largest centers were Taraco, located near the northern lake edge, and Pukara, located 50 km to the northwest in the grassland pampas. Our data reveal that a high-status residential section of Taraco was burned in the first century A.D., after which economic activity in the area dramatically declined. Coincident with this massive fire at Taraco, Pukara adopted many of the characteristics of state societies and emerged as an expanding regional polity. We conclude that organized conflict, beginning approximately 500 B.C.E., is a significant factor in the evolution of the archaic state in the northern Titicaca Basin.

  16. Groundwater quality in the Northern Coast Ranges Basins, California

    USGS Publications Warehouse

    Mathany, Timothy M.; Belitz, Kenneth

    2015-01-01

    Recharge to the groundwater system is primarily from mixture of ambient sources, including direct percolation of precipitation and irrigation waters, infiltration of runoff from surrounding hills/areas, seepage from rivers and creeks, and subsurface inflow (from non-alluvial geologic units that bound the alluvial basins). The primary sources of discharge are evaporation, discharge to streams, and water pumped for municipal supply and irrigation.

  17. Palynology and organic/isotope geochemistry of the Mae Moh Basin, Northern Thailand

    SciTech Connect

    Minh, L.V.; Abrajano, T.; Burden, E.; Winsor, L. ); Ratanasthien, B. )

    1994-07-01

    The Mae Moh basin is one of several Tertiary intermontane basins in northern Thailand, whose evolution has been linked to the collision of the Indian plate with the Eurasian plate since the early Eocene. As in most of these basins, lacustrine/swamp sedimentation in the Mae Moh basin can be broadly divided into an Oligocene to Miocene synrift sequence and a Miocene to Quarternary postrift sequence. The dominance of swamp flora recognized from spore and pollen assemblages (e.g., Polypodiidites usmensis, Verrucatosporites, Cyrtostachys), as well as the abundance of macrophytes and woody debris, indicate overwhelming hot and humid swamp conditions, with lake development restricted to relatively small areas. The distribution of alkanes and their compound-specific carbon isotope compositions are used to further show climatic variations affecting the lake/swamp ecology during the deposition of the synrift sequence.

  18. Structural features of northern Tarim basin: Implications for regional tectonics and petroleum traps

    SciTech Connect

    Dong Jia; Juafu Lu; Dongsheng Cai

    1998-01-01

    The rhombus-shaped Tarim basin in northwestern China is controlled mainly by two left-lateral strike-slip systems: the northeast-trending Altun fault zone along its southeastern side and the northeast-trending Aheqi fault zone along its northwestern side. In this paper, we discuss the northern Tarim basin`s structural features, which include three main tectonic units: the Kalpin uplift, the Kuqa depression, and the North Tarim uplift along the northern margin of the Tarim basin. Structural mapping in the Kalpin uplift shows that a series of imbricated thrust sheets have been overprinted by strike-slip faulting. The amount of strike-slip displacement is estimated to be 148 km by restoration of strike-slip structures in the uplift. The Kuqa depression is a Mesozoic-Cenozoic foredeep depression with well-developed flat-ramp structures and fault-related folds. The Baicheng basin, a Quaternary pull-apart basin, developed at the center of the Kuqa depression. Subsurface structures in the North Tarim uplift can be divided into the Mesozoic-Cenozoic and the Paleozoic lithotectonic sequences in seismic profiles. The Paleozoic litho-tectonic sequence exhibits the interference of earlier left-lateral and later right-lateral strike-slip structures. Many normal faults in the Mesozoic-Cenozoic litho-tectonic sequence form the negative flower structures in the North Tarim uplift; these structures commonly directly overlie the positive flower structures in the Paleozoic litho-tectonic sequence. The interference regions of the northwest-trending and northeast-trending folds in the Paleozoic tectonic sequence have been identified to have the best trap structures. Our structural analysis indicates that the Tarim basin is a transpressional foreland basin rejuvenated during the Cenozoic.

  19. Estimating flows in ungauged river basins in northern Mozambique

    NASA Astrophysics Data System (ADS)

    Minihane, M.

    2011-12-01

    In many regions across the globe, there are limited streamflow observations and therefore limited knowledge of availability of surface water resources. In many cases, these rivers lie in countries that would benefit from economic development and improved access to water and sanitation services, both of which are linked to water resources. Additional information about streamflow in these watersheds is critical to water resources planning and economic development strategies. In southeastern Africa, the remote Rovuma River lies on the border between Mozambique and Tanzania. There are limited historic measurements in the main tributary and no recent observations. Improved knowledge of the water resource availability and inter-annual variability of the Rovuma River will enhance transboundary river basin management discussions for this river basin. While major rivers farther south in the country are more closely monitored, those in the north have gauging stations with only scattered observations and have not been active since the early 1980's. Reliable estimates of historic conditions are fundamental to water resources planning. This work aims to provide estimates in these rivers and to quantify uncertainty and bounds on those estimates. A combination of methods is used to estimate historic flows: simple index gauge methods such as the drainage area ratio method and mean flow ratio method, a statistical regression method, a combination of an index gauge method and global gridded runoff data, and a hydrological model. These results are compared to in-situ streamflow estimates based on stage measurements and rating curves for the basins and time frames for which data is available. The evaluation of the methods is based on an efficiency ratio, bias, and representation of seasonality and inter-annual variability. Use of gridded global datasets, either with the mean flow ratio method or a hydrological model, appears to provide improved estimates over use of local observations

  20. Paleotectonic controls on sedimentation in northern Williston basin area, Saskatchewan

    SciTech Connect

    Kent, D.M.

    1983-08-01

    The Williston basin lies within the so-called stable cratonic interior and would not be expected to have had the same intensity of tectonic activity as is generally considered to be characteristic of cratonic margin sedimentary basins. From time to time, however, other structural features appear to have been effective controls on sediment distribution patterns. In southern Saskatchewan, one of the most active of these was the Swift current platform. This feature appears to have been sufficiently positive during early Paleozoic time to have caused a distinct thinning of those sediments over it. The platform was mildly positive during other periods of sedimentation, as well as during periods of erosion. It was a site of widespread salt solution during Mesozoic time, which was also its time of major tectonic fluctuation, as well as being the period when it had the most significant influence on sedimentation. Southeastern Saskatchewan is the locale for some significant regional gravity and magnetic anomalies which appear related to exposed structural zones in the Precambrian Shield. A major gravity anomaly on the extreme eastern side of the province is on trend with the Nelson River zone of Manitoba and a magnetic anomaly (Camfield-Gough conductor zone) can be traced to the Wollaston trend in north-central Saskatchewan. The Camfield-Gough zone is particularly significant in that it lies along the axis of the Hummingbird trough, an area affected by basement-controlled early salt solution, and it extends southward into the United States, where it is flanked by a number of local multizone oil-producing structures in North Dakota and Montana.

  1. Near-real-time cheatgrass percent cover in the Northern Great Basin, USA, 2015

    USGS Publications Warehouse

    Boyte, Stephen; Wylie, Bruce K.

    2016-01-01

    Cheatgrass (Bromus tectorum L.) dramatically changes shrub steppe ecosystems in the Northern Great Basin, United States.Current-season cheatgrass location and percent cover are difficult to estimate rapidly.We explain the development of a near-real-time cheatgrass percent cover dataset and map in the Northern Great Basin for the current year (2015), display the current year’s map, provide analysis of the map, and provide a website link to download the map (as a PDF) and the associated dataset.The near-real-time cheatgrass percent cover dataset and map were consistent with non-expedited, historical cheatgrass percent cover datasets and maps.Having cheatgrass maps available mid-summer can help land managers, policy makers, and Geographic Information Systems personnel as they work to protect socially relevant areas such as critical wildlife habitats.

  2. Spatial databases of the Humboldt Basin mineral resource assessment, northern Nevada

    USGS Publications Warehouse

    Mihalasky, Mark J.; Moyer, Lorre A.

    2004-01-01

    This report describes the origin, generation, and format of tract map databases for deposit types that accompany the metallic mineral resource assessment for the Humboldt River Basin, northern Nevada, (Wallace and others, 2004, Chapter 2). The deposit types include pluton-related polymetallic, sedimentary rock-hosted Au-Ag, and epithermal Au-Ag. The tract maps constitute only part of the assessment, which also includes new research and data for northern Nevada, discussions on land classification, and interpretation of the assessment maps. The purpose of the assessment was to identify areas that may have a greater favorability for undiscovered metallic mineral deposits, provide analysis of the mineral-resource favorability, and present the assessment of the Humboldt River basin and adjacent areas in a digital format using a Geographic Information System (GIS).

  3. Unusual Radar Backscatter Properties Along the Northern Rim of Imbrium Basin

    NASA Technical Reports Server (NTRS)

    Thompson, T. W.; Campbell, Bruce A.

    2005-01-01

    In general, radar backscatter from the lunar terrae is 2-4 times that of the maria. One exception to this is the terra terrain along the northern rim of Imbrium Basin. The highlands that surround Sinus Iridum and crater Plato have long-wavelength (70-cm) radar backscatter that is comparable to or lower than that from the adjacent maria. We are studying new 70-cm radar images and earlier multispectral data to better constrain the regional geology.

  4. Flathead River Basin Hydrologic Observatory, Northern Rocky Mountains

    NASA Astrophysics Data System (ADS)

    Woessner, W. W.; Running, S. W.; Potts, D. F.; Kimball, J. S.; Deluca, T. H.; Fagre, D. B.; Makepeace, S.; Hendrix, M. S.; Lorang, M. S.; Ellis, B. K.; Lafave, J.; Harper, J.

    2004-12-01

    We are proposing the 22, 515 km2 glacially-sculpted Flathead River Basin located in Montana and British Columbia as a Hydrologic Observatory. This hydrologic landscape is diverse and includes large pristine watersheds, rapidly developing intermountain valleys, and a 95 km2 regulated reservoir and 510 km2 lake. The basin has a topographic gradient of over 2,339 m, and spans high alpine to arid climatic zones and a range of biomes. Stream flows are snow-melt dominated and underpinned by groundwater baseflow. The site headwaters contain 37 glaciers and thousands of square kilometers of watersheds in which fire and disease are the only disturbances. In contrast, the HO also contains watersheds at multiple scales that were dominated by glaciers within the last 100 years but are now glacier free, impacted by timber harvests and fires of varying ages to varying degrees, modified by water management practices including irrigation diversion and dams, and altered by development for homes, cities and agriculture. This Observatory provides a sensitive monitor of historic and future climatic shifts, air shed influences and impacts, and the consequences of land and water management practices on the hydrologic system. The HO watersheds are some of the only pristine watersheds left in the contiguous U.S.. They provide critical habitat for key species including the native threaten bull trout and lynx, and the listed western cutthroat trout, bald eagle, gray wolf and the grizzly bear. For the last several thousand years this system has been dominated by snow-melt runoff and moderated by large quantities of water stored in glacial ice. However, the timing and magnitude of droughts and summer flows have changed dramatically. With the information that can be gleaned from sediment cores and landscape records at different scales, this HO provides scientists with opportunities to establish baseline watershed conditions and data on natural hydrologic variability within the system. Such a

  5. Early Tertiary subsidence and sedimentary facies - northern Sirte Basin, Libya

    SciTech Connect

    Gumati, Y.D.; Kanes, W.H.

    1985-01-01

    The subsidence curves and subsidence rate curves for the Sirte basin, constructed from the stratigraphic record, show that subsidence was continuous throughout Late Cretaceous and Tertiary times, reaching a maximum during the Paleocene and Eocene, when a major reactivation of faults occurred. Shales and carbonates were deposited during all of the Late Cretaceous and Tertiary. Abrupt lateral facies changes occur from the platform areas toward the deeper troughs along with steep downdip thickening. These conditions were probably assisted by contemporaneous faulting along structurally weak hinge lines where the dominant structural elements are normal step faults. The absence of upper Paleozoic and lower Mesozoic sediments suggests that the area was domed, faulted, and eroded during the late Mesozoic. As a result of crustal extension during the Paleocene, a marked lithologic and structural change occurred. The Heira Shale succeeded the Kalash Limestone in the Marada trough. Reactivation of the earlier faults, accompanied by an increase in the sediment supply from the south, caused these lower Paleocene shales to cover the entire area, with the exception of the old highs where carbonate deposition continued. An intercalation of shales and carbonates provides a sensitive indicator of change of depth and sediment type.

  6. Early Tertiary subsidence and sedimentary facies - Northern Sirte Basin, Libya

    SciTech Connect

    Gumati, Y.D.; Kanes, W.H.

    1985-12-01

    The subsidence curves and subsidence rate curves for the Sirte basin, constructed from the stratigraphic record, show that subsidence was continuous throughout Late Cretaceous and Tertiary times, reaching a maximum during the Paleocene and Eocene, when a major reactivation of faults occurred. Shales and carbonates were deposited during all of the Late Cretaceous and Tertiary. Abrupt lateral facies changes occur from the platform areas toward the deeper troughs along with steep downdip thickening. The absence of upper Paleozoic and lower Mesozoic sediments suggests that the area was domed, faulted, and eroded during the late Mesozoic. As a result of crustal extension during the Paleocene, a marked lithologic and structural change occurred. The Heira Shale succeeded the Kalash Limestone in the Marada trough. Reactivation of the earlier faults, accompanied by an increase in the sediment supply from the south, caused these lower Paleocene shales to cover the entire area, with the exception of the old highs where carbonate deposition continued. An intercalation of shales and carbonates provides a sensitive indicator of change of depth and sediment type. 14 figures.

  7. Paleozoic unconformities favorable for uranium concentration in northern Appalachian basin

    SciTech Connect

    Dennison, J.M.

    1986-05-01

    Unconformities can redistribute uranium from protore rock as ground water moves through poorly consolidated strata beneath the erosion surface, or later moves along the unconformity. Groundwater could migrate farther than in present-day lithified Paleozoic strata in the Appalachian basin, now locally deformed by the Taconic and Allegheny orogenies. Several paleoaquifer systems could have developed uranium geochemical cells. Sandstone mineralogy, occurrences of fluvial strata, and reduzate facies are important factors. Other possibilities include silcrete developed during desert exposure, and uranium concentrated in paleokarst. Thirteen unconformities are evaluated to determine favorable areas for uranium concentration. Cambrian Potsdam sandstone (New York) contains arkoses and possible silcretes just above crystalline basement. Unconformities involving beveled sandstones and possible fluvial strata include Cambrian Hardyston sandstone (New Jersey), Cambrian Potsdam Sandstone (New York), Ordovician Oswego and Juniata formations (Pennsylvania and New York), Silurian Medina Group (New York), and Silurian Vernon, High Falls, and Longwood formations (New York and New Jersey). Devonian Catskill Formation is beveled by Pennsylvanian strata (New York and Pennsylvania). The pre-Pennsylvanian unconformity also bevels Lower Mississippian Pocono, Knapp, and Waverly strata (Pennsylvania, New York, and Ohio), truncates Upper Mississippian Mauch Chunk Formation (Pennsylvania), and forms paleokarst on Mississippian Loyalhanna Limestone (Pennsylvania) and Maxville Limestone (Ohio). Strata associated with these unconformities contain several reports of uranium. Unconformities unfavorable for uranium concentration occur beneath the Middle Ordovician (New York), Middle Devonian (Ohio and New York), and Upper Devonian (Ohio and New York); these involve marine strata overlying marine strata and probably much submarine erosion.

  8. Diachronous fault array growth within continental rift basins: Quantitative analyses from the East Shetland Basin, northern North Sea

    NASA Astrophysics Data System (ADS)

    Claringbould, Johan; Bell, Rebecca; Jackson, Christopher; Gawthorpe, Robert; Odinsen, Tore

    2016-04-01

    The evolution of rift basins has been the subject of many studies, however, these studies have been mainly restricted to investigating the geometry of rift-related fault arrays. The relative timing of development of individual faults that make up the fault array is not yet well constrained. First-order tectono-stratigraphic models for rifts predict that normal faults develop broadly synchronously throughout the basin during a temporally distinct 'syn-rift' episode. However, largely due to the mechanical interaction between adjacent structures, distinctly diachronous activity is known to occur on the scale of individual fault segments and systems. Our limited understanding of how individual segments and systems contribute to array-scale strain largely reflects the limited dimension and resolution of the data available and methods applied. Here we utilize a regional extensive subsurface dataset comprising multiple 3D seismic MegaSurveys (10,000 km2), long (>75km) 2D seismic profiles, and exploration wells, to investigate the evolution of the fault array in the East Shetland Basin, North Viking Graben, northern North Sea. Previous studies propose this basin formed in response to multiphase rifting during two temporally distinct extensional phases in the Permian-Triassic and Middle-to-Late Jurassic, separated by a period of tectonic quiescence and thermal subsidence in the Early Jurassic. We document the timing of growth of individual structures within the rift-related fault array across the East Shetland Basin, constraining the progressive migration of strain from pre-Triassic-to-Late Jurassic. The methods used include (i) qualitative isochron map analysis, (ii) quantitative syn-kinematic deposit thickness difference across fault & expansion index calculations, and (iii) along fault throw-depth & backstripped displacement-length analyses. In contrast to established models, we demonstrate that the initiation, growth, and cessation of individual fault segments and

  9. Stratigraphic context of fossil hominids from the Omo group deposits: northern Turkana Basin, Kenya and Ethiopia

    SciTech Connect

    Feibel, C.S.; Brown, F.H.; McDougall, I.

    1989-04-01

    The chronometric framework developed for Plio-Pleistocene deposits of the northern Turkana Basin is reviewed in light of recent advances in lithostratigraphy, geochemical correlation, paleomagnetic stratigraphy, and isotopic dating. The sequence is tightly controlled by 20 precise ages on volcanic materials. These ages are internally consistent but are at variance with estimates for the boundaries of the magnetic polarity time scale by about 0.07 my. This discrepancy can be only partially resolved at present. Based on the established chronometric framework and stratigraphic sequences, depositional ages can be estimated for significant marker beds. These ages can in turn be used to constrain the 449 hominid specimens thus far reported from the basin. Ages for most hominid specimens can be estimated with a precision of +/- 0.05 my. In addition, the chronometric framework will be applicable to other paleontological collections, archeological excavations, and future discoveries in the basin.

  10. Reactive Transport of Nitrate in Northern California Groundwater basins: An Integrated Characterization and Modeling Approach

    NASA Astrophysics Data System (ADS)

    Esser, B. K.; Moran, J. E.; Hudson, G. B.; Carle, S. F.; McNab, W.; Tompson, A. F.; Moore, K.; Beller, H.; Kane, S.; Eaton, G.

    2003-12-01

    More than 1/3 of active public drinking water supply wells in California produce water with nitrate-N levels indicative of anthropogenic inputs (> 4 mg/L). Understanding how the distribution of nitrate in California groundwater basins will evolve is vital to water supply and infrastructure planning. To address this need, we are studying the basin-scale reactive transport of nitrate in the Livermore and Llagas basins of Northern California. Both basins have increasingly urban populations heavily reliant on groundwater. A distinct nitrate "plume" exists in the Livermore Basin (Alameda County) whereas pervasive nitrate contamination exists in shallow groundwaters of the Llagas Basin (Santa Clara County). The sources and timing of nitrate contamination in these basins are not definitively known; septic systems, irrigated agriculture and livestock operations exist or have existed in both areas. The role of denitrification in controlling nitrate distribution is also unknown; dissolved oxygen levels are sufficiently low in portions of each basin as to indicate the potential for denitrification. We have collected water from 60 wells, and are determining both groundwater age (by the 3H/3He method) and the extent of denitrification (by the excess N2 method). Excess nitrogen is being determined by both membrane-inlet and noble gas mass spectrometry, using Ar and Ne content to account for atmospheric N2. We are also analyzing for stable istotopes of nitrate and water, nitrate co-contaminants, and general water quality parameters. Preliminary analysis of archival water district data from both basins suggests positive correlations of nitrate with Ca+2, Mg+2 and bicarbonate and negative correlation with pH. In the Llagas Basin, a negative correlation also exists between nitrate and temperature. Flow path-oriented reactive transport modeling is being explored as a tool to aid in the identification of both the sources of nitrate and evidence for denitrification in both basins

  11. MOLA Topography of Impact Basins in the Northern Hemisphere of Mars

    NASA Technical Reports Server (NTRS)

    Frey, Herbert; Sakimoto, S. E. H.; Roark, J. H.

    1998-01-01

    Coverage of the northern hemisphere of Mars by the Mars Orbiter Laser Altimeter (MOLA) during the aerobraking hiatus and the two Science Phasing Operation periods provides improved definition and characterization of large impact basins. Gridded MOLA data show the Utopia Basin has a pronounced bowl-like structure, as opposed to the interior rises suggested by the earlier USGS DEM. The elevation structure is concentric about the basin center as mapped by McGill. In particular, the proposed inner ring closely follows the -4 km contour over much of the southern, western and northwestern sides. Higher topography along portions of the dichotomy boundary aligns with the basin's outer ring. High topography in the polar region also occurs where the outer ring should lie, raising the possibility that perhaps some of the polar topography is due to basin structure as well as ice. Two MOLA passes near Phison Rupes provide evidence for a large "stealth" hole where Viking imagery show little evidence of any major structure. The 2 km deep, 600 km wide depression at 31OW, 3ON is as large as the Cassini impact basin 1000 km to the SW. While Cassini is easily recognized in image data, the "MOLA Hole" is not. If this depression is a deeply eroded and buried impact basin (as perhaps suggested by a decrease in the crater density and somewhat smoother terrain than in adjacent areas), it is not clear why it has managed to maintain its great depth. In Tempe at the dichotomy boundary a 300 km wide impact basin is revealed by pronounced bowl-like topography centered at 87W, 47N, even though only about 1/3 of the basin rim structure is obvious. The basin lies on a sloping boundary zone, with the more buried N rim up to 2 km below the rugged S rim. A similar N-S asymmetry in basin ring structure occurs for the much larger Isidis Basin, where the S rim rises 6 km but the subdued N rim rises barely 2 km above the floor. There is essentially no topographic expression of the main ring in the NE

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

    NASA Astrophysics Data System (ADS)

    Benvenuti, Marco; Bonini, Marco; Moroni, Adriana

    2016-09-01

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

  13. Cenozoic evolution of Qaidam basin controlled by the transition of two epochs basin-forming dynamics systems in the northern Tibetan plateau

    NASA Astrophysics Data System (ADS)

    Guan, Shuwei; Zhang, Shuichang; Ma, Dade; Wang, Liqun; Wang, LiangShu; Yu, Xiangjiang

    2015-04-01

    Cenozoic basin-froming dynamics of Qaidam basin, in which Cenozoic occupies more than 90% of sediments, has been an open question. Transversal wave velocity structure of Qaidam basin and its nearby region imaged from ambient noise and earthquake data reveal the low velocity layer uplifting from south to north in middle crust, under which the lower crust and upper mantle lithosphere are obviously deflected toward the eastern Kunlun orogenic belt in the south and Qilian orogenic belt in the north. These deformation features in lithosphere reflect that the deep dynamics process of Qaidam basin is similar with the type foreland basin. But Cenozoic Qaidam basin is located in a narrow and semi-closed tectonic environment, structural displacement from the southwest Qaidam has achieved, even exceeded, the north-south width of basin, which disabled the development of stable craton and wedge deposition form of a typical foreland basin. Our basin-scale AMS study in seven locations of Qaidam basin reveal that the palaeo-stress orientation of middle to late Eocene Xiaganchaigou Formation is N-S direction, while that of early to middle Miocene Xiayoushashan Formation is NE-SW direction. Moreover, the early N-S compression is more intense in the northern Qaidam basin than that in the western Qaidam basin, while the late NE-SW compression, which dominates the modern NW-SE trending fold axial traces, is more intense in the southwestern Qaidam basin than that in the northern Qaidam basin. So we infer that Cenozoic structural deformation of Qaidam basin maybe dominated by two epochs basin-forming dynamics systems. The transition of these two epochs systems also dominated the Cenozoic basin evolution pattern from open state to closed state. The kinematic properties and pattern of late basin-forming dynamics system with NE-SW compression since Miocene can also be verified from the distinctive topography in southwestern Qaidam basin, where there are a series of arched mountains between

  14. The Frasnian-Famennian boundary (Upper Devonian) in black shale sequences: US Southern Midcontinent, Illinois Basin, and northern Appalachian Basin

    SciTech Connect

    Over, D.J. . Dept. of Geological Sciences)

    1994-04-01

    The Frasnian-Famennian (F/F) boundary in the Woodford Shale of the US southern Midcontinent, Sweetland Creek Shale of the Illinois Basin, and the Hanover Shale of the northern Appalachian Basin is recognized to a discrete horizon. In each locality the boundary is marked by evidence of a disconformity: phosphate nodules, concentration of conodonts, or coated and corroded grains. The Woodford Shale consists of finely laminated pyritic organic-rich shale containing interbeds of greenish shale and chert. The F/F boundary horizon is marked by a concentration of conodonts and phosphatic nodules. The boundary lag horizon contains Pa. linguliformis, Pa. subperlobtata, Pa. delicatula delicatula, and Pa. triangularis. Underlying laminations contain Ancyrognathus ubiquitus and Pa. triangularis indicating that the disconformity is within the uppermost MN Zone 13 or Lower triangularis Zone. The upper portion of the Type Sweetland Creek Shale consists of dark organic-rich shales. The F/F boundary is located within an interval containing three green shale interbeds. Palmatolepis triangularis in the absence of Frasnian species first occurs in the middle green shale. In the thick Upper Devonian clastic sequence of the northern Appalachian Basin the F/F boundary is within an interval of interbedded pyritic green and organic-rich silty shales of the Hanover Shale. At Irish Gulf strata containing Pa. triangularis overlie finely laminated dark shales containing Pa. bogartensis, Pa. triangularis, Pa. winchell, Ancyrodella curvata, and Icriodus alternatus. The conodont fauna transition is below a conodont-rich laminae containing a Famennian fauna that marks the boundary horizon.

  15. 3D Fault Geometry and Basin Evolution in the Northern Continental Borderland Offshore Southern California

    NASA Astrophysics Data System (ADS)

    Schindler, C. S.; Nicholson, C.; Sorlien, C.

    2007-12-01

    Grids of recently released high-quality industry multichannel seismic (MCS) reflection data, combined with bathymetry and offshore well data are used to map digital 3D fault surfaces and stratigraphic reference horizons in the northern Continental Borderland offshore of southern California. This area experienced large-scale oblique crustal extension and translation associated with the initiation and development of the Pacific-North American plate boundary. The 3D surfaces of structure and stratigraphy can thus be used to better understand and evaluate regional patterns of uplift, subsidence, fault interaction and other aspects of plate boundary deformation. Our mapping in Santa Cruz basin and on Santa Rosa and Santa Cruz-Catalina Ridge reveals an unusual pattern of faulting, folding and basin subsidence. This subsidence is significant (up to 3-4 km since early-Miocene time) and is responsible for the development of several major Borderland basins. Vertical motions can be estimated from an early-Miocene unconformity that likely represents a paleo-horizontal, near-paleo-sea-level erosional surface. As such, it can be used to reconstruct Borderland forearc geometry prior to rifting, subsidence and subsequent basin inversion. Major findings to date include: (a) a better characterization of the complex 3D geometry and pinch-out of the eastern edge of the northern forearc Nicolas terrane and its implications for Borderland basin development, plate reconstructions, and vertical motions associated with oblique rifting; (b) recognition that the East Santa Cruz Basin fault, previously thought to be a predominantly high-angle, large- displacement right-slip fault representing the eastern edge of the Nicolas terrane, is in fact a series of reactivated right-stepping, NE-dipping reverse-separation faults; (c) discovery that NW-striking faults associated with Santa Cruz-Catalina Ridge bend west into a horse-tail structure to interact with and contribute to the southern frontal

  16. Extensional collapse along the Sevier Desert reflection, northern Sevier Desert basin, western United States

    NASA Astrophysics Data System (ADS)

    Coogan, James C.; Decelles, Peter G.

    1996-10-01

    Newly released and previously published seismic reflection data from the northern Sevier Desert basin provide a complete seismic transect between the tilted western margin of the basin and the eastern breakaway zone. When tied to well and surface age data, the transect delineates a continuum of extensional fault and basin fill geometries that developed between late Oligocene and Pleistocene time across the basin. A minimum of 18 km of top-to-the-west normal displacement is estimated across the Sevier Desert from only the most conspicuous growth geometries and offsets across listric normal faults that sole downward into the Sevier Desert reflection (SDR). The SDR clearly marks a normal fault zone beneath the entire basin, where stratal truncations are imaged for 50% of the 39 km length of the reflection east of the Cricket Mountains block. Restoration of extensional displacement along this entire 39 km fault length is necessary to reconstruct the pre-Oligocene configuration and erosion level of Sevier thrust sheets across the Sevier Desert area. The SDR normal fault zone underlies the former topographic crest of the Sevier orogenic belt, where it accommodated extensional collapse after cessation of regional contractile tectonism.

  17. Late Miocene and Pliocene synorogenic sedimentation in northern Livermore basin, California

    SciTech Connect

    Isaacson, K.A.; Andersen, D.W.

    1987-05-01

    Late Tertiary synorogenic sedimentation in the northern Livermore basin, Contra Costa County, California, has recorded two major changes in provenance. Changes in clast composition of fluvial conglomerates reflect regional tectonic reorganization as the San Andreas fault system began to evolve at this latitude. Shallow marine deposition of Sierran andesitic sediment gave way at approximately 8 Ma to fluvially dominated deposition of sediment from a local, graywacke-rich, Coast Range source. Deposition of reworked andesitic material prior to 5.5 Ma records development of anticlinal uplifts along trends of the present Altamont Hills and Calaveras fault system. By 4 Ma, the areal extent of the subsiding basin had increased; the Altamont Hills continued to be uplifted, but the Calaveras fault region began to subside rapidly. Late Miocene and Pliocene deformation of the Livermore basin area extended over a broad zone east of the developing transform fault system. Structures that developed included broad synclinal basins and gentle anticlinal uplifts that had topographic expression but were not deeply incised. Intense deformation of the basin and uplift of Mount Diablo occurred after 3 Ma.

  18. The Northern end of the Dead Sea Basin: Geometry from reflection seismic evidence

    USGS Publications Warehouse

    Al-Zoubi, A. S.; Heinrichs, T.; Qabbani, I.; ten Brink, U.S.

    2007-01-01

    Recently released reflection seismic lines from the Eastern side of the Jordan River north of the Dead Sea were interpreted by using borehole data and incorporated with the previously published seismic lines of the eastern side of the Jordan River. For the first time, the lines from the eastern side of the Jordan River were combined with the published reflection seismic lines from the western side of the Jordan River. In the complete cross sections, the inner deep basin is strongly asymmetric toward the Jericho Fault supporting the interpretation of this segment of the fault as the long-lived and presently active part of the Dead Sea Transform. There is no indication for a shift of the depocenter toward a hypothetical eastern major fault with time, as recently suggested. Rather, the north-eastern margin of the deep basin takes the form of a large flexure, modestly faulted. In the N-S-section along its depocenter, the floor of the basin at its northern end appears to deepen continuously by roughly 0.5??km over 10??km distance, without evidence of a transverse fault. The asymmetric and gently-dipping shape of the basin can be explained by models in which the basin is located outside the area of overlap between en-echelon strike-slip faults. ?? 2007 Elsevier B.V. All rights reserved.

  19. Advective and Conductive Heat Flow Budget Across the Wagner Basin, Northern Gulf of California

    NASA Astrophysics Data System (ADS)

    Neumann, F.; Negrete-Aranda, R.; Contreras, J.; Müller, C.; Hutnak, M.; Gonzalez-Fernandez, A.; Harris, R. N.; Sclater, J. G.

    2015-12-01

    In May 2015, we conducted a cruise across the northern Gulf of California, an area of continental rift basin formation and rapid deposition of sediments. The cruise was undertaken aboard the R/V Alpha Helix; our goal was to study variation in superficial conductive heat flow, lateral changes in the shallow thermal conductivity structure, and advective transport of heat across the Wagner basin. We used a Fielax heat flow probe with 22 thermistors that can penetrate up to 6 m into the sediment cover. The resulting data set includes 53 new heat flow measurements collected along three profiles. The longest profile (42 km) contains 30 measurements spaced 1-2 km apart. The western part of the Wagner basin (hanging wall block) exhibit low to normal conductive heat flow whereas the eastern part of the basin (foot wall block) heat flow is high to very high (up to 2500 mWm-2). Two other short profiles (12 km long each) focused on resolving an extremely high heat flow anomaly up to 15 Wm-2 located near the intersection between the Wagner bounding fault system and the Cerro Prieto fault. We hypothesize that the contrasting heat flow values observed across the Wagner basin are due to horizontal water circulation through sand layers and fault pathways of high permeability. Circulation appears to be from west (recharge zone) to east (discharge zone). Additionally, our results reveal strong vertical advection of heat due to dehydration reactions and compaction of fine grained sediments.

  20. New Evidence for Salt Tectonics in Bannu Basin, Northern Pakistan from Seismic Imaging

    NASA Astrophysics Data System (ADS)

    Ahmad Abir, I.; Khan, S.; Aziz, G.; Tariq, S.

    2015-12-01

    The Trans Indus-Salt Range, located in northern Pakistan, is one of the most tectonically active fold-and-thrust belts and comprises three main regions of Potwar-Salt Range, Kohat-Surghar Range and the Bannu Basin-Khisor Range. Of these, Bannu Basin is the least studied and only a handful of publicly accessible datasets and publications are available. 2D seismic profiles and well data from this area have been recently made public and provide a more comprehensive picture of the structural geology and stratigraphy of the Bannu Basin. Well data analysis plus structural and stratigraphic interpretation of seismic profiles were integrated with existing data from the Bannu Basin to generate structural cross sections and fence diagrams. The fence diagrams indicate the presence of salt and salt diapirism that is concentrated along the Marwat anticline. Salt diapirs and transpressive structures were identified at the terminations of wrench zones. Evidence of salt enables the concept that Infra-Cambrian salt may have been the sole detachment for Bannu Basin and not Cambrian shale as previously proposed. A shallower Eocene/Paleocene detachment has also been identified. Bannu Basin indicates structural and stratigraphic similarities with the Potwar-Salt Range and exhibits thin-skinned deformation. Our results suggest that these similarities are likely due to the presence of salt and its role as a detachment in both regions. Therefore, we consider the Bannu Basin as the western extension of the Potwar-Salt Range and that the Infra-Cambrian salt extends westward of the Kalabagh fault.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  2. Diachronous Growth of Normal Fault Systems in Multiphase Rift Basins: Structural Evolution of the East Shetland Basin, Northern North Sea

    NASA Astrophysics Data System (ADS)

    Claringbould, Johan S.; Bell, Rebecca E.; A-L. Jackson, Christopher; Gawthorpe, Robert L.; Odinsen, Tore

    2015-04-01

    Our ability to determine the structural evolution and interaction of fault systems (kinematically linked group of faults that are in the km to 10s of km scale) within a rift basin is typically limited by the spatial extent and temporal resolution of the available data and methods used. Physical and numerical models provide predictions on how fault systems nucleate, grow and interact, but these models need to be tested with natural examples. Although field studies and individual 3D seismic surveys can provide a detailed structural evolution of individual fault systems, they are often spatially limited and cannot be used examine the interaction of fault systems throughout the entire basin. In contrast, regional subsurface studies, commonly conducted on widely spaced 2D seismic surveys, are able to capture the general structural evolution of a rift basin, but lack the spatial and temporal detail. Moreover, these studies typically describe the structural evolution of rifts as comprising multiple discrete tectonic stages (i.e. pre-, syn- and post-rift). This simplified approach does not, however, consider that the timing of activity can be strongly diachronous along and between faults that form part of a kinematically linked system within a rift basin. This study focuses on the East Shetland Basin (ESB), a multiphase rift basin located on the western margin of the North Viking Graben, northern North Sea. Most previous studies suggest the basin evolved in response to two discrete phases of extension in the Permian-Triassic and Middle-Late Jurassic, with the overall geometry of the latter rift to be the result of selective reactivation of faults associated with the former rift. Gradually eastwards thickening intra-rift strata (deposited between two rift phases) that form wedges between and within fault blocks have led to two strongly contrasting tectonic interpretations: (i) Early-Middle Jurassic differential thermal subsidence after Permian-Triassic rifting; or (ii

  3. Water quality in the Northern Rockies Intermontane basins, Idaho, Montana, and Washington, 1999-2001

    USGS Publications Warehouse

    Clark, Gregory M.; Caldwell, Rodney R.; Maret, Terry R.; Bowers, Craig L.; Dutton, DeAnn M.; Becksmith, Michael A.

    2003-01-01

    This report contains the major findings of a 1999–2001 assessment of water quality in the Northern Rockies Intermontane Basins. It is one of a series of reports by the National Water-Quality Assessment (NAWQA) Program that present major findings in 51 major river basins and aquifer systems across the Nation. In these reports, water quality is discussed in terms of local, State, and regional issues. Conditions in a particular basin or aquifer system are compared to conditions found elsewhere and to selected national benchmarks, such as those for drinking-water quality and the protection of aquatic organisms. This report is intended for individuals working with water-resource issues in Federal, State, or local agencies, universities, public interest groups, or in the private sector. The information will be useful in addressing a number of current issues, such as the effects of agricultural and urban land use on water quality, human health, drinking water, source-water protection, hypoxia and excessive growth of algae and plants, pesticide registration, and monitoring and sampling strategies. This report is also for individuals who wish to know more about the quality of streams and ground water in areas near where they live, and how that water quality compares to the quality of water in other areas across the Nation. The water-quality conditions in the Northern Rockies Intermontane Basins summarized in this report are discussed in detail in other reports that can be accessed from (http://id.water.usgs.gov/nrok/index.html). Detailed technical information, data and analyses, collection and analytical methodology, models, graphs, and maps that support the findings presented in this report in addition to reports in this series from other basins can be accessed from the national NAWQA Web site (http://water.usgs.gov/nawqa).

  4. Tectonic fabric of northern North Fiji and Lau basins from GLORIA sidescan

    SciTech Connect

    Tiffin, D.L. ); Clarke, J.E.H.; Johnson, D. ); Jarvis, P. ); Hill, P. ); Huggett, Q.; Pearson, L. ); Price, R. )

    1990-06-01

    GLORIA mosaics, Seabeam, and seismic data over parts of the backarc New Hebrides arc, northwest and central North Fiji basin, Fiji Fracture Zone north of Fiji, Peggy Ridge, northeast Lau basin, northern Tonga arc, northwestern Tonga Trench, and Western Samoa reveal a complex tectonic framework for the region. Two triple junctions and several rifts are clearly delineated by outcrops and ridges of neovolcanic rocks. Backarc troughs in the New Hebrides Arc are commonly floored by volcanic rocks with little sediment cover. The locus of major faults are well defined in places by volcanic ridges and scarps. On the Fiji Fracture Zone north of Fiji, scarps indicate the trace, but west of Fiji it disappears for about 100 km, becoming well pronounced again near the central North Fiji basin triple junction. At Peggy Ridge a very extensive area of sheet-like volcanics indicates activity extends northeast from Peggy Ridge toward the western extension of the Tonga Trench passing west of Niuafo'ou Island, possibly marking a fault-to-trench transition. East of Niuafo'ou Island, backarc spreading close to the Tofua Arc is seen at a nascent triple junction, its northern arm approaching close to the western Tonga Trench. Long linear fault scarps in the trench result from bending of the crust. Only a few areas, including the seafloor north of Samoa, are mainly sediment covered. Two known hydrothermal deposits near the two triple junctions have been imaged, but other mapped areas of extensive neo-volcanics in the vicinity of propagators and pull-apart basins suggest sites for further investigation. The prevalence of ridge propagators and extensional basins suggests their significant role in the development of the region.

  5. Seismites in slowly deforming regions - evidence for diffuse seismicity in the northern Ejina Basin (Gaxun Nur Basin)

    NASA Astrophysics Data System (ADS)

    Rudersdorf, Andreas; Hartmann, Kai; Reicherter, Klaus

    2014-05-01

    Past earthquakes leave various types of evidence on the Earth's surface. Seismic waves in water-saturated sediments lead to the deformation of original bedding, unconformities and event layers. The term "seismite" was introduced to describe the various co-seismic effects of earthquakes on sediments that range from principally brittle deformation (e.g., neptunian dykes, hydrofracturing) to soft-sediment deformation (e.g., liquefaction, convolution, seismoslumps). The Gobi belt of left-lateral transpression between the active deformation zones of the Tibetan Plateau - driven by the India-Eurasian continental collision, and the Gobi-Altai mountain ranges - showing large-scale faulting as far-field responses of above-named collision, exhibits large and remote desert environments with rugged and low topography that are overprinted by strong eolian erosion by competing wind systems. The Ejina Basin (Gaxun Nur Basin, Inner Mongolia) has been extensively studied and shows evidence for neotectonic faulting (indirectly dated by affected lacustrine sediments) through detected lineaments, morphotectonic investigation and geophysical reconnaissance. The instrumental seismicity is low. Different modes of faulting are discussed, with both WSW-ENE and conjugate trending strike-slip faulting with associated pull-apart basins, as well as far-field-induced NW-SE trending thrusts, being found. The basin is a huge endorheic delta built by the Hei River (chin. Heihe, mong. Ruoshui) and comprises Quaternary sedimentary successions up to 300 m in thickness, which overlie Neogene and Mesozoic sedimentary bedrock. The Quaternary sedimentary successions consist of changing intercalations of eolian and fluvial sands, lacustrine silts and clays and playa evaporites. Positive landforms, such as yardangs (wind-sculpted clay terraces) in the lower reaches of the Hei River (northern Ejina Basin) serve as valuable outcrops for paleoseismic investigation. They exhibit units of deformed sediments

  6. Organic geochemistry and petroleum geology, tectonics and basin analysis of southern Tarim and northern Qaidam basins, northwest China

    NASA Astrophysics Data System (ADS)

    Hanson, Andrew Dean

    Organic geochemistry of oils from the Tarim basin, NW China, distinguish at least seven genetic groups of oils. The largest group are derived from Middle-Upper Ordovician anoxic slope-facies marls coincident with the margins of structural uplifts. Other groups include non-marine derived oils in the Luntai uplift, from southwest Tarim, in the Kuqa depression, and west of the Bachu uplift. A seep sample from west of Kashi clusters with Luntai oils. These results suggest that numerous source-rock horizons occur, but they are really restricted. Organic geochemistry of oils from northern Qaidam defines a family of hypersaline, anoxic lacustrine derived oils. Cenozoic outcrop samples from northern Qaidam are too organic lean to be of source quality, but dark laminated upper Oligocene mudstones from the Shi 28 well are of fair to good quality. Biomarkers provide a good correlation between the oils and the core samples. Organic matter is from algae and bacteria and lacks terrestrial material. Hydrocarbons are contained in upper Oligocene, Miocene, and Pliocene reservoirs. Eight oils are from NW Qaidam, but one sample comes from NE Qaidam, an area previously believed to only produce oils derived from Jurassic source rocks. Thus an unidentified Cenozoic source rock occurs in NE Qaidam. Thermal modeling indicates generation occurred in northwestern Qaidam within the last 3 million years, agreeing with observed low maturity biomarker parameters. Cenozoic stratigraphy in northern Qaidam and southern Tarim basins record the tectonic history of the surrounding structural/topographic elements. Paleocurrents record flow away from adjacent ranges from the Miocene to the present. Provenance data tie sediments to adjacent structural elements. Petrography indicates increasingly immature sandstones in Miocene and younger sediments relative to pre-Miocene samples. Apatite fission-track results from southeastern Tarim yield a cooling age of 17 +/- 1 Ma indicative of unroofing since at

  7. Miocene woods from the Qaidam Basin on northern Qinghai-Tibet Plateau with implications for paleoenvironmental change

    NASA Astrophysics Data System (ADS)

    Cheng, Ye-Ming; Yang, Xiao-Nan

    2016-02-01

    The Qaidam Basin with the most complete Cenozoic sedimentary preservation in northern Qinghai-Tibet Plateau is a key area for studying uplift and environmental change of the plateau. Three types of woods, Ulmus (Ulmaceae), Leguminosae (?) (angiosperm) and Cupressaceae (gymnosperm) were recognized from the large-scale preservation of fossil woods in late Miocene Shang Youshashan Formation in northern Qaidam Basin on the Qinghai-Tibet Plateau. Both investigations of their Nearest Living Relatives (NLRs) and previous grassland mammal evidences suggest that there have been temperate deciduous broad-leaved forest and needle-leaved forest with grass in northern Qaidam Basin during the late Miocene in contrast to the desert vegetation found there nowadays. The presence of the ancient forest steppe further implies that the southern part of the plateau used to be adequately low, so that the Indian and East Asian monsoons could approach the northern area and to accommodate the vegetation in late Miocene.

  8. Study of southern CHAONAN sag lower continental slope basin deposition character in Northern South China Sea

    NASA Astrophysics Data System (ADS)

    Tang, Y.

    2009-12-01

    Northern South China Sea Margin locates in Eurasian plate,Indian-Australia plate,Pacific Plates.The South China Sea had underwent a complicated tectonic evolution in Cenozoic.During rifting,the continental shelf and slope forms a series of Cenozoic sedimentary basins,including Qiongdongnan basin,Pearl River Mouth basin,Taixinan basin.These basins fill in thick Cenozoic fluviolacustrine facies,transitional facies,marine facies,abyssal facies sediment,recording the evolution history of South China Sea Margin rifting and ocean basin extending.The studies of tectonics and deposition of depression in the Southern Chaonan Sag of lower continental slope in the Norther South China Sea were dealt with,based on the sequence stratigraphy and depositional facies interpretation of seismic profiles acquired by cruises of“China and Germany Joint Study on Marine Geosciences in the South China Sea”and“The formation,evolution and key issues of important resources in China marginal sea",and combining with ODP 1148 cole and LW33-1-1 well.The free-air gravity anomaly of the break up of the continental and ocean appears comparatively low negative anomaly traps which extended in EW,it is the reflection of passive margin gravitational effect.Bouguer gravity anomaly is comparatively low which is gradient zone extended NE-SW.Magnetic anomaly lies in Magnetic Quiet Zone at the Northern Continental Margin of the South China Sea.The Cenozoic sediments of lower continental slope in Southern Chaonan Sag can be divided into five stratum interface:SB5.5,SB10.5,SB16.5,SB23.8 and Hg,their ages are of Pliocene-Quaternary,late Miocene,middle Miocene,early Miocene,paleogene.The tectonic evolution of low continental slope depressions can be divided into rifting,rifting-depression transitional and depression stages,while their depositional environments change from river to shallow marine and abyssa1,which results in different topography in different stages.The topographic evolvement in the study

  9. Developing the Late Quaternary Record of Pluvial Lake Clover, Northern Great Basin, U.S.A

    NASA Astrophysics Data System (ADS)

    Laabs, B. J.; Munroe, J. S.

    2009-12-01

    Lake Clover was one of numerous closed-basin pluvial lakes that formed in the northern Great Basin during the Pleistocene. The geomorphic record of the lake includes continuous shoreline ridges and spits at altitudes of as much as 25 m above the modern playa surface. The history of Lake Clover is poorly known compared to those of the larger lakes Lahontan and Bonneville, but can provide a useful framework for understanding regional-scale environmental changes during the latest Pleistocene. Shoreline ridges of Lake Clover are preserved at altitudes of ca. 1729, 1725, 1719, and 1715 m asl, which correspond to intervals when the lake attained a surface area of 788, 726, 618, and 524 km2, respectively. Although the chronology of highstands at these altitudes is still being developed (through radiocarbon and luminescence-dating methods), the morphology and orientations of prominent shoreline features provide clues to regional air-circulation patterns during highstands. The highest shoreline is represented by a gravel ridge that can be traced nearly continuously around the perimeter of the lake basin. The ridge is uniformly developed along shorelines of differing aspect, suggesting that the wind field during the ice-free season was not dominated by a single direction. Along the eastern and western shores of the basin, the lower shorelines are manifested by a similar gravel ridge. However, in other sectors of the basin, features associated with progressively lower shorelines reveal an increasing dominance of northward longshore drift. The most dramatic features correspond with the 1719 m shoreline and include 1) a pronounced V-shaped, northward projecting spit at the southern end of the basin, 2) a 3-km long spit projecting to the north-northwest along the northeastern shoreline, and 3) a tombolo connecting a former island to the northern shore. Together these features suggest that dominant wind directions became more southerly during the ice-free season when the lake

  10. Visan miospore biostratigraphy and correlation of the Poti Formation (Parnaba Basin, northern Brazil).

    PubMed

    Melo; Loboziak

    2000-10-01

    The Poti Formation, which consists mainly of sandstones with minor proportions of carbonaceous shales and other siliciclastic lithologies, represents all the Viséan strata thus far recorded in the Parnaíba Basin, northern Brazil.Well-preserved miospores featuring species with both Southern Euramerican and Gondwanan affinities have been recovered from this formation in four well sections. The most characteristic species are listed in this paper, and brief systematic descriptions are presented for the most significant species, along with comments on their biostratigraphy. A new generic combination is proposed: Cordylosporites magnidictyus (Playford and Helby) Loboziak and Melo comb. nov. Comparisons with miospores illustrated from the Grand Erg Occidental, Algerian Sahara, are tentatively proposed.In terms of the Western European Carboniferous palynozonation, miospore assemblages from the Poti Formation are assignable to the Perotrilites tessellatus-Schulzospora campyloptera (TC)-Raistrickia nigra-Triquitrites marginatus (NM) zonal range. This corresponds to the upper part of the Holkerian and the whole Asbian, which are British regional stages for the lower to middle parts of the upper Viséan. The Viséan age formerly attributed to biostratigraphic interval XII of Petrobras' regional palynostratigraphic scheme is therefore confirmed. As already noted in our recent investigations of the Faro Formation in the Amazon Basin and equivalent strata of the Solimões Basin, latest Tournaisian and early to middle Viséan sections are either absent or barren of characteristic miospores in the Parnaíba Basin as well.

  11. The Alpine tectonic evolution of the Danube Basin and its northern periphery (southwestern Slovakia)

    NASA Astrophysics Data System (ADS)

    Hók, Jozef; Kováč, Michal; Pelech, Ondrej; Pešková, Ivana; Vojtko, Rastislav; Králiková, Silvia

    2016-10-01

    The tectonic evolution of the pre-Cenozoic basement, as well as the Cenozoic structures within the Danube Basin (DB) and its northern periphery are presented. The lowermost portion of the pre-Cenozoic basement is formed by the Tatricum Unit which was tectonically affected by the subduction of the Vahicum / Penninicum distal continental crust during the Turonian. Tectonically disintegrated Tatricum overlaid the post-Turonian to Lower Eocene sediments that are considered a part of the Vahicum wedge-top basin. These sediments are overthrust with the Fatricum and Hronicum cover nappes. The Danube Basin Transversal Fault (DBTF) oriented along a NW-SE course divided the pre-Neogene basement of the DB into two parts. The southwestern part of the DB pre-Neogene basement is eroded to the crystalline complexes while the Palaeogene and Mesozoic sediments are overlaid by the Neogene deposits on the northeastern side of the DBTF. The DBTF was activated as a dextral fault during the Late Oligocene - Earliest Miocene. During the Early Miocene (Karpatian - Early Badenian) it was active as a normal fault. In the Middle - Late Miocene the dominant tectonic regime with NW - SE oriented extension led to the disintegration of the elevated pre-Neogene basement under the simple and pure shear mechanisms into several NE - SW oriented horst and graben structures with successive subsidence generally from west to east. The extensional tectonics with the perpendicular NE - SW orientation of the Shmin persists in the Danube Basin from the ?Middle Pleistocene to the present.

  12. Decreased runoff response to precipitation, Little Missouri River Basin, northern Great Plains, USA

    USGS Publications Warehouse

    Griffin, Eleanor R.; Friedman, Jonathan M.

    2017-01-01

    High variability in precipitation and streamflow in the semiarid northern Great Plains causes large uncertainty in water availability. This uncertainty is compounded by potential effects of future climate change. We examined historical variability in annual and growing season precipitation, temperature, and streamflow within the Little Missouri River Basin and identified differences in the runoff response to precipitation for the period 1976-2012 compared to 1939-1975 (n = 37 years in both cases). Computed mean values for the second half of the record showed little change (<5%) in annual or growing season precipitation, but average annual runoff at the basin outlet decreased by 22%, with 66% of the reduction in flow occurring during the growing season. Our results show a statistically significant (p < 0.10) 27% decrease in the annual runoff response to precipitation (runoff ratio). Surface-water withdrawals for various uses appear to account for <12% of the reduction in average annual flow volume, and we found no published or reported evidence of substantial flow reduction caused by groundwater pumping in this basin. Results of our analysis suggest that increases in monthly average maximum and minimum temperatures, including >1°C increases in January through March, are the dominant driver of the observed decrease in runoff response to precipitation in the Little Missouri River Basin.

  13. Monitoring and modeling of two alluvial aquifers in lower Nestos river basin, Northern Greece.

    PubMed

    Boskidis, Ioannis; Pisinaras, Vassilios; Petalas, Christos; Tsihrintzis, Vassilios A

    2012-01-01

    A groundwater monitoring and modeling program in two aquifers within the lower Nestos river basin in Northern Greece is presented. A monitoring network of 54 wells was developed in the two study areas, and groundwater level measurements and water quality sample analyses were conducted for a period of 2.5 years, from March 2007 to October 2009. The field data were used for the calibration and verification of the mathematical model MODFLOW in the two aquifers. The validated model was used to examine ten alternative management scenarios regarding groundwater abstraction in the two aquifers. The study showed that MODFLOW, if properly validated, is a useful and flexible tool in groundwater resources management.

  14. Ground-water quality in northern Ada County, lower Boise River basin, Idaho, 1985-96

    USGS Publications Warehouse

    Parliman, D.J.; Spinazola, Joseph M.

    1998-01-01

    In October 1992, the U.S. Geological Survey (USGS), in cooperation with the Idaho Division of Environmental Quality, Boise Regional Office (IDEQ-BRO), began a comprehensive study of ground-water quality in the lower Boise River Basin. The study in northern Ada County has been completed, and this report presents selected results of investigations in that area. Results and discussion presented herein are based on information in publications listed under “References Cited” on the last page of this Fact Sheet.

  15. Geologic history and hydrogeologic units of intermontane basins of the northern Rocky Mountains, Montana and Idaho

    USGS Publications Warehouse

    Tuck, L.K.; Briar, David W.; Clark, David W.

    1996-01-01

    The Regional Aquifer-System Analysis (RASA) program is a series of studies by the U.S. Geological Survey (USGS) to analyze regional ground-water systems that compose a major portion of the Nation’s water supply (Sun, 1986). The Northern Rocky Mountains Intermontane Basins is one of the study regions in this national program. The main objectives of the RASA studies are to: (1) describe the ground-water systems as they exist today, (2) analyze the known changes that have led to the system's present condition, (3) combine results of previous studies in a regional analysis, where possible, and (4) provide means by which effects of future ground-water development can be estimated.The purpose of this study, which began in 1990, was to increase understanding of the hydrogeology of the intermontane basins of the Northern Rocky Mountains area. This report is Chapter Cofa three-part series and describes the quality of ground-water and surface water in the study area. Chapter A (Tück and others, 1996) describes the geologic history and generalized hydrogeologic units. Chapter B (Briar and others, 1996) describes the general distribution of ground-watcrlcwels in basin-fill deposits,Water-quality data illustrated in this report represent the distribution of concentrations and composition of dissolved solids in ground-water and surface water in the intermontane areas. The chemistry of ground and surface water in the intermontane areas is influenced by the chemical and physical nature of the rocks in the basin deposits of the valleys and surrounding bedrock in the mountains.

  16. Ground-water levels in intermontane basins of the northern Rocky Mountains, Montana and Idaho

    USGS Publications Warehouse

    Briar, David W.; Lawlor, S.M.; Stone, M.A.; Parliman, D.J.; Schaefer, J.L.; Kendy, Eloise

    1996-01-01

    The Regional Aquifer-System Analysis (RASA) program is a series of studies by the U.S. Geological Survey (USGS) to analyze regional ground-water systems that compose a major portion of the Nation's water supply (Sun, 1986). The Northern Rocky Mountains Intermontane Basins is one of the study regions in this national program. The main objectives of the RASA studies are to (1) describe the groundwater systems as they exist today, (2) analyze the known changes that have led to the systems present condition, (3) combine results of previous studies in a regional analysis, where possible, and (4) provide means by which effects of future ground-water development can be estimated.The purpose of this study, which began in 1990, was to increase understanding of the hydrogeology of the intermontane basins of the Northern Rocky Mountains area. This report is Chapter B of a three-part series and shows the general distribution of ground-water levels in basin-fill deposits in the study area. Chapter A (Tuck and others, 1996) describes the geologic history and generalized hydrogeologic units. Chapter C (Clark and Dutton, 1996) describes the quality of ground and surface waters in the study area.Ground-water levels shown in this report were measured primarily during summer 1991 and summer 1992; however, historical water levels were used for areas where more recent data could not be obtained. The information provided allows for the evaluation of general directions of ground-water flow, identification of recharge and discharge areas, and determination of hydraulic gradients within basin-fill deposits.

  17. Holocene faulting in the Bellingham forearc basin: upper-plate deformation at the northern end of the Cascadia subduction zone

    USGS Publications Warehouse

    Kelsey, Harvey M.; Sherrod, Brian L.; Blakely, Richard J.; Haugerud, Ralph A.

    2013-01-01

    The northern Cascadia forearc takes up most of the strain transmitted northward via the Oregon Coast block from the northward-migrating Sierra Nevada block. The north-south contractional strain in the forearc manifests in upper-plate faults active during the Holocene, the northern-most components of which are faults within the Bellingham Basin. The Bellingham Basin is the northern of four basins of the actively deforming northern Cascadia forearc. A set of Holocene faults, Drayton Harbor, Birch Bay, and Sandy Point faults, occur within the Bellingham Basin and can be traced from onshore to offshore using a combination of aeromagnetic lineaments, paleoseismic investigations and scarps identified using LiDAR imagery. With the recognition of such Holocene faults, the northernmost margin of the actively deforming Cascadia forearc extends 60 km north of the previously recognized limit of Holocene forearc deformation. Although to date no Holocene faults are recognized at the northern boundary of the Bellingham Basin, which is 15 km north of the international border, there is no compelling tectonic reason to expect that Holocene faults are limited to south of the international border.

  18. Paleozoic evolution of active margin basins in the southern Central Andes (northwestern Argentina and northern Chile)

    NASA Astrophysics Data System (ADS)

    Bahlburg, H.; Breitkreuz, C.

    The geodynamic evolution of the Paleozoic continental margin of Gondwana in the region of the southern Central Andes is characterized by the westward progression of orogenic basin formation through time. The Ordovician basin in the northwest Argentinian Cordillera Oriental and Puna originated as an Early Ordovician back-arc basin. The contemporaneous magmatic arc of an east-dipping subduction zone was presumably located in northern Chile. In the back-arc basin, a ca. 3500 meter, fining-up volcaniclastic apron connected to the arc formed during the Arenigian. Increased subsidence in the late Arenigian allowed for the accomodation of large volumes of volcaniclastic turbidites during the Middle Ordovician. Subsidence and sedimentation were caused by the onset of collision between the para-autochthonous Arequipa Massif Terrane (AMT) and the South American margin at the Arenigian-Llanvirnian transition. This led to eastward thrusting of the arc complex over its back-arc basin and, consequently, to its transformation into a marine foreland basin. As a result of thrusting in the west, a flexural bulge formed in the east, leading to uplift and emergence of the Cordillera Oriental shelf during the Guandacol Event at the Arenigian-Llanvirnian transition. The basin fill was folded during the terminal collision of the AMT during the Oclóyic Orogeny (Ashgillian). The folded strata were intruded post-tectonically by the presumably Silurian granitoids of the "Faja Eruptiva de la Puna Oriental." The orogeny led to the formation of the positive area of the Arco Puneño. West of the Arco Puneño, a further marine basin developed during the Early Devonian, the eastern shelf of which occupied the area of the Cordillera Occidental, Depresión Preandina, and Precordillera. The corresponding deep marine turbidite basin was located in the region of the Cordillera de la Costa. Deposition continued until the basin fill was folded in the early Late Carboniferous Toco Orogeny. The basin

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

    USGS Publications Warehouse

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

    1974-01-01

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

  20. Geochronologic Constraints on the Permian-Triassic Northern Source Region of the Sverdrup Basin, Canadian Arctic Islands

    NASA Astrophysics Data System (ADS)

    Anfinson, Owen A.; Embry, Ashton F.; Stockli, Daniel F.

    2016-11-01

    Detrital zircon U-Pb ages are used to provide constraints on the geologic evolution of the sediment source area(s) north of the Sverdrup Basin from the middle Permian to Late Triassic. Previous research on facies relationships and sediment progradation patterns of late Paleozoic and Triassic strata from the northern portion of Sverdrup Basin indicate that substantial sediment was derived from north of the basin. Utilizing LA-ICP-MS U-Pb geochronology we have analyzed detrital zircons from these northerly derived strata, including sandstones of four Late Triassic (Norian) outcrop samples the northeast Sverdrup Basin, and two Triassic (Olenekian and Carnian) and two Permian (Roadian and Wordian) samples from wells in the northwestern Sverdrup Basin. The samples from northwestern Sverdrup Basin contain abundant Early Mississippian (350 Ma) to Early Ordovician (460 Ma), late Cambrian (500 Ma) to Cryogenian (650 Ma), and early Tonian (960 Ma) to Orosirian (2050 Ma) detrital zircon. The detrital zircon ages from these samples are similar to zircon age components of Late Devonian siliciclastic strata of the Franklinian foreland basin, and we suggest a similar source area, a low-lying landmass north of the Sverdrup basin, which included extensive Devonian foreland basin strata. The U-Pb detrital zircon age components of northerly-derived Late Triassic strata of northeastern Sverdrup Basin samples are similar to the Permian and Triassic Northwestern Sverdrup Samples, but also contain a substantial age component of Triassic (201 Ma) to Middle Mississippian (340 Ma) detrital zircons, suggesting an additional source area. The only well documented source for such zircons in the Arctic region is the Ural Orogen. Consequently, it is postulated that, in the Late Triassic, sediment was transported 1500 km from the northern Urals, across the northern landmass, all the way to the shoreline of northeastern Sverdrup Basin.

  1. Precipitation variability and future projections for water resources management in Tunisia Northern Coastal basins

    NASA Astrophysics Data System (ADS)

    Bargaoui, Z.; Tramblay, Y.; Lawin, E.; Servat, E.

    2012-04-01

    Northern Tunisia is the rainiest part of the country. This is the reason why the surface water resources management scheme of Tunisia is principally focused on that area. The strategic situation of the study area, with respect to surface water resources, encourages the investigation of the climate change impacts as projected by climate models. The goal of this study is first to compare the observed precipitation with climate model outputs, and then to evaluate the future changes projected by the models. The study area is subdivided into three regions: the transboundary Medjerda basin, the northern coastal basins (Zouara, Sidi El Barrack, Lake Ichkeul basins) and the eastern coastal basins (Cap-Bon region and wadi Meliane basins). Rainfall data are collected in this area since the late 19th century. A data base provided by the Tunisian hydrological service (DGRE) is including 388 stations with monthly precipitation data over the period 1961-2000. Recent advances in downscaling have provided regional climate model (RCM) simulations at a coarser resolution than Global climate models (GCM). However there is a need to validate RCM outputs with respect to observed precipitation data before using them to make future projections. For that purpose, an ensemble of RCM simulations provided by the European Union-funded project ENSEMBLES (www. ensembles-eu.org) are used. Six RCM models runs (CNR_ARPEGE, DMI_ARPEGE, DMI_BCM, ICT_ECHAM, SMH_BCM, SMH_ECHAM) are tested for a control period (1961-2000) and two projection periods (2011-2050 and 2051-2090).The models efficiency in reproducing seasonal precipitation amounts and variability over the study domain is evaluated. A 1-km monthly precipitation grid is first obtained through the interpolation of rainfall observations during the period 1961-2000 with kriging techniques. Monthly precipitation series averaged over the three great regions are built for comparison for the control period. The RCM outputs are evaluated with respect

  2. Geology, Streamflow, and Water Chemistry of the Talufofo Stream Basin, Saipan, Northern Mariana Islands

    USGS Publications Warehouse

    Izuka, Scot K.; Ewart, Charles J.

    1995-01-01

    A study of the geology, streamflow, and water chemistry of Talufofo Stream Basin, Saipan, Commonwealth of the Northern Mariana Islands, was undertaken to determine the flow characteristics of Talufofo Stream and the relation to the geology of the drainage basin. The Commonwealth government is exploring the feasibility of using water from Talufofo Stream to supplement Saipan's stressed municipal water supply. Streamflow records from gaging stations on the principal forks of Talufofo Stream indicate that peak streamflows and long-term average flow are higher at the South Fork gaging station than at the Middle Fork gaging station because the drainage area of the South Fork gaging station is larger, but persistent base flow from ground-water discharge during dry weather is greater in the Middle Fork gaging station. The sum of the average flows at the Middle Fork and South Fork gaging stations, plus an estimate of the average flow at a point in the lower reaches of the North Fork, is about 2.96 cubic feet per second or 1.91 million gallons per day. Although this average represents the theoretical maximum long-term draft rate possible from the Talufofo Stream Basin if an adequate reservoir can be built, the actual amount of surface water available will be less because of evaporation, leaks, induced infiltration, and reservoir-design constraints. Base-flow characteristics, such as stream seepage and spring discharge, are related to geology of the basin. Base flow in the Talufofo Stream Basin originates as discharge from springs near the base of limestones located in the headwaters of Talufofo Stream, flows over low-permeability volcanic rocks in the middle reaches, and seeps back into the high-permeability limestones in the lower reaches. Water sampled from Talufofo Stream during base flow had high dissolved-calcium concentrations (between 35 and 98 milligrams per liter), characteristic of water from a limestone aquifer. Concentrations of potassium, sodium, and chloride

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

    NASA Astrophysics Data System (ADS)

    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

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

    PubMed

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

    2008-09-09

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

  5. Sequence stratigraphy and depositional systems of the Lower Silurian Medina Group, northern Appalachian basin

    SciTech Connect

    Castle, J.W. )

    1991-08-01

    Detailed sedimentological analysis of 3500 ft of continuous core from 44 wells in Pennsylvania, Ohio, Ontario, New York, and West Virginia, combined with regional study of geophysical logs, results in new interpretations of sequence stratigraphy and depositional systems in Lower Silurian siliciclastic rocks of the northern Appalachian basin. Above a type-1 sequence boundary at the base of the Medina Group are a lowstand systems tract and a transgressive systems tract that are represented, respectively, by the Whirlpool Sandstone and by the overlying Cabot Head Shale. The thickest sandstones in the Medina Group occur in the Grimsby Sandstone, which is interpreted as a highstand systems tract with basinward-prograding parasequences. Sea level rise after Grimsby parasequence deposition is represented by marine-shelf shale in the uppermost part of the Medina Group. Based on facies successions in the cores, four mappable depositional systems are interpreted for the Grimsby Sandstone and correlative sandstone units; (1) wave-dominated middle shelf, (2) wave- and tide-influenced inner shelf, (3) tide dominated shoreline, and (4) fluvial. The wave-dominated middle-shelf system, which includes very fine-grained shelf-ridge sandstones encased in marine shale, is the most basinward system, occurring from Ontario through parts of eastern Ohio. Shoreward, across the northern Appalachian basin, the influence of tidal processes relative to wave processes generally increased, which may have been related to distance across the shelf, water depth, and shoreline configuration. The shoreline may have been deltaic in some areas and straight in other areas.

  6. Reservoir development in Brahaney northwest and Patricia fields, northern Midland basin, Texas

    SciTech Connect

    Mazzullo, L.J.

    1990-02-01

    Porous pay zones in the Silurian-Devonian section of the northern Midland basin, Texas, vary stratigraphically, as well as structurally, with their locations beneath the pre-Woodford unconformity. These variations are related to at least two major periods of widespread pre-Woodford tectonism and erosion. A major unconformable surface, present at the top of the Lower Silurian Fusselman formation, was later modified by tectonism and erosion immediately preceding deposition of the Woodford Shale. In places where the Fusselman subcrops beneath the Woodford, its capacity for reservoir development is dependent upon the severity of geologic events that affected the formation during the two major tectonic/erosional events. Where the Wristen and Thirtyone formations subcrop, their reservoir capacity depends upon the extent of structuring and subsequent erosion immediately prior to Woodford deposition. Two pre-Woodford oil fields in the northern Midland basin illustrate geologic complexity that bears on the successful application of subsurface mapping in defining potential pay zones. Brahaney Northwest field in Yoakum County is productive from fractured, coarse crystalline Silurian-Devonian dolomites on subtle, fault-bounded structures. These structures, defined seismically on the base of the Woodford, do not reveal the more complex structural and stratigraphic variations within the reservoir itself. Patricia field in Dawson County is productive from Fusselman carbonates where upper Fusselman structural and topographic relief coincides with post-Woodford faulting and low-relief anticlinal closure as defined at the base of the Woodford.

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

    NASA Astrophysics Data System (ADS)

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

    2009-06-01

    The phylum Bacteroidetes represents one of the most abundant bacterial groups of marine and freshwater bacterioplankton. We investigated the diversity of Bacteroidetes in water and sediment samples from three evaporitic basins located in the highlands of northern Chile. We used both 16S rRNA gene clone libraries created with targeted Bacteroidetes-specific primers and separation of specifically amplified gene fragments by denaturing gradient gel electrophoresis (DGGE). DGGE analysis revealed a reduced richness of these organisms in samples from Salar de Huasco (two to four DGGE bands) increasing in Salar de Ascotán (two to seven DGGE bands) and Laguna Tebenquiche at Salar de Atacama (four to eight DGGE bands). Cluster analysis (WPGMA) of DGGE bands showed that bands from Salar de Huasco and Salar de Ascotán grouped together and samples from Salar de Atacama formed separate clusters in water and sediment samples, reflecting different Bacteroidetes communities between sites. Most of the sequences analyzed belonged to the family Flavobacteriaceae and clustered with the genera Psychroflexus, Gillisia, Maribacter, Muricauda, Flavobacterium, and Salegentibacter. The most abundant phylotype was highly related to Psychroflexus spp. and was recovered from all three study sites. The similarity of the analyzed sequences with their closest relatives in GenBank was typically <97% and notably lower when compared with type strains, demonstrating the unique character of these sequences. Culture efforts will be necessary to get a better description of the diversity of this group in saline evaporitic basins of northern Chile.

  8. The Cenozoic on-shore basins of Northern Vietnam: Biostratigraphy, vertebrate and invertebrate faunas

    NASA Astrophysics Data System (ADS)

    Böhme, Madelaine; Prieto, Jérôme; Schneider, Simon; Hung, Nguyen Viet; Quang, Do Duc; Tran, Dang Ngoc

    2011-01-01

    A first account of paleontological data from three Cenozoic on-shore basins in Northern Vietnam, i.e. the Na Duong, Cao Bang, and Hang Mon basins, reveals a rich fossil fauna and flora of supposed Oligocene age, offering a great potential for taxonomic, paleoenvironmental, and paleobiogeographic studies. Two excavation campaigns unearthed well-preserved fossil remains of mammals, crocodiles, at least six turtle species, some 20 fish taxa, some other 20 mollusc species, and different plant remains. The majority of these taxa are regarded as new to science. However, close affinities to modern faunas of northern Southeast Asia demonstrate the importance of these fossils for an evaluation of the biological history of this modern biodiversity hot spot. Moreover, the fossil assemblages may help to disentangle the intricate Cenozoic tectonic evolution of Southeast Asia by application of paleobiogeographic modelling. Finally, the discovery of complex paleo-food-webs and the presence of several taxa indicative of certain ecological conditions provide a solid base for autecologic, synecologic and paleoclimatic studies. The potential biostratigraphic value of the macrofauna has to be demonstrated yet, as evolutionary concepts for most of the respective groups have not been proposed to date.

  9. Sequence stratigraphy of the Pennsylvanian Morrow Formation, northern Delaware basin, New Mexico

    SciTech Connect

    Bay, A.R.; Baltensperger, P.A. )

    1990-05-01

    Stratigraphic sequence analysis of the Pennsylvanian Morrow Formation is a new technique useful in predicting and understanding shifts in sand trends that can help locate Morrow gas reservoirs in the mature northern Delaware basin. Morrow sandstone reservoirs are fluvial deltaic channel fill and transgressive beach deposits that typically are 10-30 ft thick and consistently less than 1 mi wide. Detailed mapping and correlation within the systems tracts of each sequence can high-grade specific areas in the basin for exploration. Based on subsurface log correlations, the Morrow clastics and Atoka carbonates in the northern Delaware basin are interpreted as three stratigraphic sequences bounded by subregional type I unconformities. The post-Mississippian unconformity represents the oldest sequence boundary in the Morrow-to-Atoka succession and formed as the base level dropped and the shoreline shifted at least 50 mi basinward. The uplifted Pedernal Highlands supplied sediment to dip-trending lower Morrow channels that downcut into the exposed Mississippian carbonate ramp surface. The transgressive systems tract in this sequence consists of landward-stepping, wave-dominated deltaic deposit. The Morrow shale, a regionally correlatable organic-rich shale that separates the lower Morrow from the middle Morrow, represents the highstand deposits as base level that rose to a maximum. Another base level drop occurred at the end of Morrow shale deposition and resulted in dip-trending channel-fill sandstones and, stacked landward stepping transgressive beach and offshore ridge deposits oriented parallel to strike. The highstand progradational deposits of this sequence formed a terrace that supplied a shelf margin system of deltaic and slope-apron sediments during the succeeding third sequence. The shelf margin deposits are capped by highstand shelf carbonates of the upper Morrow and lower Atoka.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  12. A Three-Dimensional View of the Tualatin and Northern Willamette Basins, Oregon, from Inversion of New Gravity Data

    NASA Astrophysics Data System (ADS)

    Langenheim, V. E.; McPhee, D. K.; Morin, R. L.; Blakely, R. J.; Wells, R. E.

    2004-12-01

    A regional gravity study was initiated during the summer of 2004 over the Tualatin and northern Willamette basins in support of ongoing seismic hazard and ground-water studies. More than 1200 new gravity measurements were acquired over the basins and surrounding areas, increasing the average spacing of 1 station per 25 km2 to 1 station per 5 km2 over much of the lowlands. To first order, the gravity data reflect the substantial density contrast (400 to 600 kg/m3) between dense Eocene oceanic basement rocks (e.g. Tillamook Volcanics and Siletz River Volcanics), exposed extensively in the Coast Range west of the valleys, and overlying Eocene to Miocene marine sedimentary rocks and Quaternary deposits. Isostatic gravity values as high as +70 mGal occur over Eocene basement rocks west of the valleys. Relatively high gravity values of ˜ +20 mGal coincide with a few scattered outcrops of the Tillamook Formation and Basalt of Waverly Heights (considered Eocene volcanic basement) on the eastern margin of the Tualatin basin, suggesting that Eocene basement extends across the Tualatin basin. However, the lower values on the eastern margin may indicate lower-density facies within the volcanic basement (i.e. breccias rather than flows) and/or a deeper oceanic slab. Both the Tualatin basin and the Willamette basin to the south are marked by gravity lows. The lowest gravity values (minus 45 mGal) of the entire region occur in the central part of the Tualatin basin, north of the intrabasinal, east-striking Beaverton Fault, whereas the gravity low over the northern Willamette basin reaches only minus 20 mGal. The two basins are separated by a broad, northeast-trending gravity high along the upthrown side of the Sherwood fault. The western margin of the Tualatin gravity low coincides with the Gales Creek fault and is marked by a steep gravity gradient, which broadens south of the Beaverton Fault. The southward continuation of the Gales Creek fault into the northern Willamette

  13. Tectonic and sedimentary evolution of the Ili Basin (northern Tien Shan, Kazakhstan)

    NASA Astrophysics Data System (ADS)

    Kley, J.; Voigt, T.; Seib, N.; Kober, M.

    2010-12-01

    The Tien Shan active intraplate orogen of Central Asia exhibits strong along-strike variations in structure. Its northern front in southeastern Kazakhstan is characterized by a fragmented array of anticlinal basement highs whose wavelengths range from c. 5 to 30 km. Range-bounding faults are mostly E- to ENE-trending thrust or reverse faults and SE-trending dextral strike-slip faults. Faults of large displacement (more than several tens of meters) are conspicuously absent. The synclinal lows between the basement highs preserve Cenozoic strata of Oligocene to Quaternary age, probably deposited in a once continuous basin (the Ili Basin) and recording the entire history of Tien Shan uplift. Very gentle, long-wavelength folds affect the Cenozoic strata. As far as visible, the basement is always folded conformably. The basin fill starts in the middle Oligocene (mammal fossils; Indricotherium horizon). The facies of these oldest deposits is characterized by fluvial deposits of a large river system and varying flood-plain deposits with intense soil formation (calcretes and gypsisols). Transport directions and quartz content of the sediments suggest they were not sourced from the nearby mountain ranges present today. The fluvial succession is followed by late Oligocene to early Miocene lake deposits which reflect the transition from an evaporitic lake/playa system to freshwater lacustrine conditions. The Oligocene to Early Miocene deposits are limited to a small area in the core of the Aktau anticline and show no relationship to the sediment succession overlying the basement in the uplifts surrounding the Aktau mountains in the north and west. There, alluvial and fluvial deposits of middle Miocene(?) age rest on deeply weathered paleosurfaces. Transport is mainly to the south. Changes in colour, grain size and ratio of channel to interchannel deposits probably reflect climatic changes. Rapid facies and thickness-changes allow the reconstruction of several alluvial fans

  14. New Seismic Reflection Profiling Across the Northern Newark Basin USA: Data Acquisition and Preliminary Results

    NASA Astrophysics Data System (ADS)

    Tymchak, M.; Collins, D.; Brown, C.; Conrad, J.; Papadeas, P.; Coueslan, M. L.; Tamulonis, K.; Goldberg, D.; Olsen, P. E.

    2011-12-01

    Deep saline formations in basins underlying major population centers represent opportunities for carbon (CO2) sequestration, but intensive surface development in such settings can hinder field operations to acquire geologic and geophysical data critical to effective characterization. Seismic-reflection is a tool that can be used to characterize basins and their potential capacity for carbon storage. The northern part of the Triassic-Jurassic Newark Rift Basin represents a potential storage opportunity for carbon as a result of its proximity to large-scale CO2 emitters; however, a lack of deep geologic and seismic data from this area has precluded evaluation of this basin to date. As part of the Department of Energy's (DOE) National Energy Technology Labs (NETL) Carbon Sequestration programs portion of the American Recovery and Reinvestment Act (ARRA)- and NYSERDA-funded TriCarb Consortium for Carbon Sequestration basin characterization project, two new seismic-reflection profiles were acquired in the northern portion of the Newark Basin in Rockland County, NY and Bergen County NJ. This densely developed region, proximal to New York City, presents a variety of challenges for seismic surveys, including route selection and access, community acceptance, high traffic volumes and associated data noise, in addition to regulatory requirements and private property limitations. In spite of these challenges, two high-resolution, perpendicular lines were successfully surveyed in late March and early April, 2011; one dip line extending 21 km (13 mi) across most of the basin (east-west), and a shorter strike line extending 8 km (5 mi, north-south). The survey lines intersected near the location of a planned 8,000 ft stratigraphic borehole to be drilled by the TriCarb consortium. Three vibroseis trucks comprised the source array. Source points were spaced at 36.5 m (120-ft) intervals and geophone accelerometers collected data at a 3.05 m (10 ft) intervals. Seismic-reflection data

  15. Giant mudwaves in the Northern Argentine Basin: born and buried by bottom currents

    NASA Astrophysics Data System (ADS)

    Borisov, Dmitrii; Murdmaa, Ivar; Ivanova, Elena; Levchenko, Oleg

    2014-05-01

    New sedimentary records and very high resolution seismic profiles collected during four cruises of the RV "Akademik Ioffe" (2011-2013) were correlated with seismic, multibeam and coring data obtained during cruises of the RV "Robert Conrad", "Knorr", "Meteor". A complex analysis of the geological-geophysical data revealed an extensive field of giant mudwaves (48 000 km2) in the northwestern Argentine Basin, South Atlantic. The symmetric waves up to 60 m in height and 4000 m in wavelength are oriented roughly parallel to contours. They partly cover the Santa Catarina Plateau and extend through the Santos Basin to the Sao Paulo Plateau. The mudwaves field is traced at the depth range from 3400 to 4000 m and divided into buried (northern) and non-buried (southern) parts. The non-buried sediment waves cover the surface of the huge drift in the Santa Catarina Plateau. The wave height increases from the drift summit to its flanks and decreases at the foot. Two cores retrieved from the drift top and its northern flank recovered muddy contourites with a greater amount of silt-size material in the core from the drift flank. The age of the recovered sediments is at least 130 ka. In the northern Santos basin, the sediment waves are buried under a large lens-like sediment body (drift?) inclined at the margins. Cores obtained from the buried part of the mudwaves field recovered an intercalation of hemipelagic clay and silty-clay contourite. The age of recovered sediments does not exceed 150 ka (Bleil et al., 1993). Contourites deposition in the study area is related to the activity of the Antarctic bottom water (AABW) contour current. The AABW flow is considered to be divided into two branches by the Santa Catarina Plateau. We suggest that this topographic obstacle causes a flow velocity increase. Wave height and grain-size variations indicate higher bottom current velocities at the plateau flanks and relative tranquil conditions at the flat summit of the plateau. The symmetric

  16. Petroleum evaluation of Ordovician black shale source rocks in northern Appalachian basin

    SciTech Connect

    Wallace, L.G.; Roen, J.B.

    1988-08-01

    A preliminary appraisal of the Ordovician black shale source beds in the northern part of the Appalachian basin shows that the sequence is composed of the Upper Ordovician Utica Shale and its correlatives. The shales range in thickness from less than 200 ft in the west to more than 600 ft in the east along the Allegheny Front. Structure contours indicate that the shales plunge from 2,000 ft below sea level in central Ohio and to about 12,000 ft below sea level in central and northeastern Pennsylvania. Geochemical analyses of 175 samples indicate that the sequence has an average total organic carbon content (TOC) of 1.34%. Conodont alteration indices (CAI) and production indices indicate that the stages of maturation range from diagenetic in the less deeply buried western part of the basin, which probably produced mostly oil, to catagenetic in the more deeply buried eastern part of the basin, which probably produced mostly gas. Potential for continued hydrocarbon generation is poor in the east and fair to moderate in the western part of the basin. If the authors assume that these rocks have produced hydrocarbons, the hydrocarbons have since migrated. Using an average TOC of 1%, an organic carbon to hydrocarbon conversion factor of 10%, and a volume of rock within the oil and gas generation range as defined by CAI values of 1.5-4, the Ordovician shale could have generated 165 billion bbl of oil or equivalent. If only 1% of the 165 billion bbl was trapped after migration, then 1.65 billion bbl of oil or equivalent would be available for discovery.

  17. Detrital fission-track-compositional signature of an orogenic chain-hinterland basin system: The case of the late Neogene Quaternary Valdelsa basin (Northern Apennines, Italy)

    NASA Astrophysics Data System (ADS)

    Balestrieri, M. L.; Benvenuti, M.; Tangocci, F.

    2013-05-01

    Detrital thermochronological data collected in syn-tectonic basin deposits are a promising tool for deciphering time and processes of the evolution of orogenic belts. Our study deals with the Valdelsa basin, one of the wider basins of central Tuscany, Italy. The Valdelsa basin is located at the rear of the Northern Apennines, a collisional orogen whose late Neogene Quaternary development is alternatively attributed to extensional and compressional regimes. These contrasting interpretations mostly rely on different reconstructions of the tectono-sedimentary evolution of several basins formed at the rear of the chain since the late Tortonian. Here, we explore the detrital thermochronological-compositional signature of tectonic and surface processes during the Valdelsa basin development. For this aim, detrital apatite fission-track analysis of 21 sand samples from the latest Messinian Gelasian fluvial to shallow marine basin deposits, has been accompanied by a clast composition analysis of 7 representative outcrops of the conglomerate facies. The grain-age distributions of the sediment samples are generally characterized by two distinct components, one younger peak (P1) varying between 5.5 ± 2.8 and 9.5 ± 1.0 Ma and one older peak (P2) varying from 15.0 ± 8.0 to 41.0 ± 10 Ma. By comparison with some bedrock ages obtained from the E-NE basin shoulder, we attributed the P2 peak to the Ligurian Units and the P1 peak to the Macigno Formation (Tuscan Units). These units are arranged one upon the other in the complex nappe pile forming the Northern Apennines orogen. While the gravel composition indicates a predominant feeding from the Ligurian units all along the sedimentary succession with a subordinate occurrence of Macigno pebbles slightly increasing upsection, the P1 peak is present even in the oldest collected sandy sediments. The early P1 occurrence reveals that the Macigno was exposed in the E-NE basin shoulder since at least the latest Messinian-early Zanclean

  18. Quaternary break-out flood sediments in the Peshawar basin of northern Pakistan

    NASA Astrophysics Data System (ADS)

    Cornwell, Kevin

    1998-11-01

    The presence of horizontally bedded, fining upward sequences of sands, silts, and clays throughout the Peshawar basin of northern Pakistan has previously been ascribed to Pleistocene lakes within the basin. Close inspection of these sediments, however, show sedimentological properties that suggest these stacked sequences are more characteristic of deposits of periodic break-out flood deposits and not lacustrine deposits. Exposures near the villages of Piran, Nowshera, Jehingira, Jalala and along the Kabul River show evidence of subaerial exposure (mudcracks and bioturbation zones), lateral continuity and fracture sets. At least three distinct cycles of deposition are apparent in the basin, each exhibiting slightly different structural and sedimentological properties. The groupings and dimensions of the rhythmite sequences indicate that within each cycle multiple episodes of flooding occurred. The absence of significant erosional and depositional features, as well as the preservation of mud rip-up clasts and bioturbation zones further suggests that the periods between episodes of flooding were probably on the order of 10 1 to 10 2 years. Evidence of ice-dams and lakes in the Indus drainage system is abundant. Cross-valley moraines and lacustrine deposits that stretch many kilometers upstream are visible in the middle Indus valley between the villages of Sazin and Shatial and Skardu. Calculated ratios of sediment to water suggest that an upstream reservoir at least 32 km 3 and perhaps as large as 128 km 3 would have been required to produce the extent of rhythmites observed in the Peshawar basin. Generating a reservoir of this size in the Indus drainage system was accomplished near the villages of Sazin-Shatial where large cross-valley moraines and upstream lacustrine sediments indicate large ice-dams as do the moraines and lacustrine sediments near Gilgit and Skardu. The origin of the graded sediments in the Peshawar basin, however, has not been correlated to the

  19. Geometry of the San Andreas Fault and Sedimentary Basin in the Northern Salton Trough

    NASA Astrophysics Data System (ADS)

    Fuis, G. S.; Bauer, K.; Catchings, R.; Goldman, M.; Ryberg, T.; Scheirer, D. S.; Langenheim, V. E.; Rymer, M. J.; Persaud, P.; Stock, J. M.; Hole, J. A.

    2014-12-01

    The Salton Seismic Imaging Project (SSIP) was undertaken, in part, to provide more accurate information on the plate-boundary faults and basin geometry in the Salton Trough region. One of these faults, the southernmost San Andreas Fault (SAF) zone in the northern Salton Trough (Coachella Valley), is considered by many to be likely to produce a large-magnitude earthquake in the near future. We report here on the geometry of the SAF and the adjacent sedimentary basin beneath the Coachella Valley. We interpret two seismic profiles in the northern Salton Trough that are orthogonal to the axis of the Coachella Valley. Seismic imaging, potential-field studies, and (or) earthquake hypocentral relocations along these profiles indicate that the active strand of the SAF dips NE. On a southern profile, through the Mecca Hills, we obtain a reflection image of the SAF zone in the depth range of 6-12 km that coincides with the microearthquake pattern reported by Hauksson et al. (2012), dipping ~ 60° NE. Steeply dipping reflectors above 6 km emerge at the surface at mapped secondary fault traces in the Mecca Hills, clearly defining a "flower structure" for the upper SAF. On the second profile, from Palm Springs to Landers, two alternative interpretations of SAF structure are possible. By one interpretation, which is based on earthquakes alone, the Banning and Garnet Hill Faults are two closely spaced faults, dipping ~ 60° NNE that pass through two aftershock clusters of the 1986 M 5.9 North Palm Springs earthquake. By the second interpretation, which is based on our reflection imaging on this line, the Banning and Garnet Hills faults converge at 10-km depth; below that depth, a single SAF dips ~ 60° NNE. In the second interpretation, the faults above 10 km resemble the flower structure interpreted beneath the Mecca Hills on our southern profile. The deeper fault in the second interpretation is subparallel to the closely spaced faults of the first interpretation but a few km

  20. Effects of contaminants on aquatic organisms in the Peace, Athabasca and Slave river basins. Northern River Basins Study synthesis report number 2

    SciTech Connect

    Carey, J.H.; Cordeiro, O.T.

    1997-01-01

    This report summarizes the activities of the Contaminants Component of the Northern River Basins Study to address the following questions: How the aquatic ecosystems in the Peace, Athabasca, and Slave river basins been affected by exposure to toxic compounds; and what long-term monitoring programs and predictive models are required to provide ongoing assessment of the state of those ecosystems. Research is described in four project areas: A basin-wide survey of biochemical responses to organochlorines and other contaminants in major fish species; a basin-wide survey of the toxicity in bottom and suspended sediments; an assessment of the utility of semi-permeable membrane devices as potential substitutes for wild fish in a long-term monitoring program; and assessment of the feasibility of using small, locally resident fish species as alternates to large adult fish in a long-term biological effects monitoring program.

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

    NASA Astrophysics Data System (ADS)

    Lee, Eun Young; Wagreich, Michael

    2017-03-01

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

  2. Crustal structure of the northern Perth Basin, southwest margin of Australia: insights from three-dimensional density models

    NASA Astrophysics Data System (ADS)

    Holzrichter, Nils; Hackney, Ron; Johnston, Stephen

    2014-01-01

    The northern Perth Basin formed from the Palaeozoic to Mesozoic within an obliquely oriented extensional rift system on the southwest continental margin of Australia. Knowledge of the basin in onshore and inboard areas reflects better accessibility and the existence of proven hydrocarbon resources. In contrast, outboard parts of the basin have poorer data coverage and hydrocarbon potential remains to be proven. In order to better constrain sediment thickness and crustal structure in the northern Perth Basin, particularly in offshore areas where coverage of seismic data is less extensive, we adopted a 3-D density modelling approach whereby simple models were initially constructed as a means to highlight the level of agreement between measured and calculated gravity. These initial models are based only on available constraints, automated extrapolation of interpreted horizons into areas without constraints, and different interpretations of Moho depth. The initial models show that the processes leading to formation of sediment depocentres in the northern Perth Basin are not governed by simple local isostasy. We show instead that a model incorporating an existing Moho model for the Australian region leads to a better fit. In this model, the Moho is deeper under the thick sediments of the onshore Dandaragan Trough. As a result, the crystalline crust between the Beagle Ridge and basin-bounding Darling Fault has a relatively constant thickness that is consistent with crustal-scale tilting and normal displacement on a steeply west-dipping Darling Fault. In the outboard parts of the basin, our modelling suggests that the deep water Zeewyck Sub-basin is a deep and steep-sided depocentre, but this area lacks constraints and uncertainty in its interpretation cannot be resolved without additional data. Despite this, the steep edges, thick sediments and the large lateral variations in Moho depth are consistent with the geometry expected of a transtensional basin. We also present

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

    NASA Astrophysics Data System (ADS)

    Hawie, N.

    2013-12-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  5. Lunar impact basins: New data for the nearside northern high latitudes and eastern limb from the second Galileo flyby

    NASA Technical Reports Server (NTRS)

    Head, J. W.; Belton, M.; Greeley, R.; Pieters, C.; Fischer, E.; Sunshine, J.; Klaasen, K.; Mcewen, A.; Becker, T.; Neukum, G.

    1993-01-01

    During the December 1992 Galileo Earth/Moon encounter the northern half of the nearside, the eastern limb, and parts of the western farside of the Moon were illuminated and in view, a geometry that was complementary to the first lunar encounter in December, 1990, which obtained images of the western limb and eastern farside. The Galileo Solid State Imaging System (SSI) obtained multispectral images for these regions during the second encounter and color ratio composite images were compiled using combinations of band ratios chosen on the basis of telescopic spectra and laboratory spectra of lunar samples. Ratios of images taken at 0.41 and 0.76 micron are sensitive to changes in the slope in the visible portion of the spectrum, and ratios of 0.99 and 0.76 micron relate to the strength of near-infrared absorptions due to iron-rich mafic minerals (0.76/0.99 ratio) such as olivine and pyroxene. Results of the analyses of the compositional diversity of the crust, maria, and Copernican craters are presented elsewhere. Primary objectives for lunar basin analysis for the second encounter include analysis of: the north polar region and the Humboldtianum basin; the characteristics of the Imbrium basin along its northern border and the symmetry of associated deposits; the origin of light plains north of Mare Frigoris and associated with several other basins; the nature and significance of pre-basin substrate; the utilization of the stereo capability to assess subtle basis structure; the identification of previously unrecognized ancient basins; basin deposits and structure for limb and farside basins; and assessment of evidence for proposed ancient basins. These data and results will be applied to addressing general problems of evaluation of the nature and origin of basin deposits, investigation of mode of ejecta emplacement and ejecta mixing, analysis of the origin of light plains deposits, analysis of basin deposit symmetry/asymmetry, investigation of basin depth of

  6. Distribution of maximum burial temperatures across northern Appalachian Basin and implications for Carboniferous sedimentation patterns

    SciTech Connect

    Johnsson, M.J.

    1986-05-01

    Clay-mineral diagenesis and apatite fission-track age data indicate that the maximum burial temperatures to which the Middle Devonian Tioga metabentonite was exposed rise abruptly from low values in western New York State to higher values in the east. The highest temperatures, which approach 175/sup 0/C, were reached just west of Syracuse. Neither the pattern nor the magnitude of burial temperatures can be explained solely by burial of the metabentonite beneath Upper Devonian sediments. Although spatial variations in the geothermal gradient could have produced the observed pattern of burial temperatures, it is more likely that Carboniferous sediments, no longer preserved in the area, were responsible for the indicated burial. The inferred presence of thick Carboniferous sequences in western New York State suggests that the Allegheny orogeny had a stronger influence on sedimentation in the northern Appalachian Basin than has been previously recognized. 25 references, 2 figures, 2 tables.

  7. Miocene non-marine diatoms from the western Cordillera basins of northern Peru

    USGS Publications Warehouse

    Fourtanier, E.; Gasse, F.; Bellier, O.; Bonhomme, M.G.; Robles, I.

    1993-01-01

    Diatom assemblages are documented from diatomite layers of two Miocene fluvio-lacustrine units from the basins of the western Cordillera of northern Peru: the Namora Formation and the Cajabamba Formation. Emphasis is given to taxa of particular stratigraphic interest. The diatom assemblages indicate for the Namora Formation the occurrence of swampy conditions with very dilute, low alkalinity water. The diatom assemblages of the Cajabamba Formation reflect the occurrence of fresh, slightly alkaline, eutrophic lakes with deep water in some samples, and swampy conditions with relatively high salt content in other samples. The Namora formation is late Miocene in age based on the diatom assemblages and radiometric analyses. The diatom layers of the Cajabamba Formation are dated as late middle to early late Miocene. -from Authors

  8. Remote Sensing of Actual Evapotranspiration at Basin Scale in the Northern Tibetan Plateau Area

    NASA Astrophysics Data System (ADS)

    Zhong, Lei; Zou, Mijun; Ma, Yaoming; Su, Zhongbo; Ma, Weiqiang; Hu, Yuanyuan; Han, Cunbo; Wang, Binbin

    2016-08-01

    Evapotranspiration(ET), as one of the most uncertain components of the water cycle, was derived in the Nagqu river basin of the northern Tibetan Plateau based on multi-sensor remote sensing data and field observations under clear-sky condition. Improved land surface albedo, improved downward shortwave radiation flux and reconstructed normalized difference vegetation index (NDVI) were coupled into the topographical enhanced surface energy balance system (TESEBS) model to estimate actual ET. The model-estimated results were compared with those determined by the combinatory method which were treated as actual ET. The results indicated that the model-estimated ET agreed well with actual ET with correlation coefficient, mean bias error and root mean square error of 0.836, 0.087 and 0.140 respectively.

  9. Comparison of offshore and onshore gas occurrences, Eel River basin, northern California

    USGS Publications Warehouse

    Lorenson, T.D.; McLaughlin, Robert J.; Kvenvolden, Keith A.; Orange, Daniel L.; Davisson, M. Lee; Brewer, Peter G.; Martin, J.B.

    1998-01-01

    The Eel River basin of northern California is a upper Cenozoic depocenter containing more than 3,000 meters of sedimentary rock located near the Mendocino triple junction. Active tectonism has resulted in folding, faulting and rapid sedimentation. Both thermogenic and microbial hydrocarbons are known to be present in the sediments. In August 1997, we sampled two submarine gas seeps, one at a water depth of 520 m that supports a chemosynthetic-based ecosystem very near an area of previously recovered gas hydrate. Another vent site was sampled in sand covered with white bacterial mats at a water depth 41 m. We compared the hydrocarbon gas composition and methane isotopic composition of these seeps with land-based gas occurrences that include: 1) a gas seep and 2) gas from a 2360 m-deep gas well.

  10. Prediction of the distribution of Glossina tachinoides (Diptera: Glossinidae) in the Volta basin of northern Ghana.

    PubMed

    Mahama, C I; Koné, A; de la Rocque, S; De Deken, R; Geerts, S

    2005-02-01

    The classification of a Landsat Thematic Mapper satellite image helped demonstrate prevailing habitat types and land use intensity in the Volta basin of the Northern Region of Ghana. A geo-referenced data layer comprising the capture results of a cross-sectional survey of Glossina tachinoides Westwood was over-laid on a data layer of habitat types within 500 m of either bank of the Volta river and its tributaries. An evaluation of the relationship between habitat types and the capture results of G. tachinoides suggested a strong preference of G. tachinoides for woodland, followed by shrubland, grassland and flood plains. The findings were used to classify the suitability of habitat types for G. tachinoides as 'high', 'medium' and 'low' and a prediction map for the distribution of G. tachinoides in the entire river network was produced. The usefulness of this method in estimating the potential distribution of G. tachinoides in an area of increasing agricultural expansion is discussed.

  11. [Diversity of soil mesofauna in Northern Taiga biogeocenosises of the Kamennaya river basin (Karelia)].

    PubMed

    Rybalov, L B; Kamaev, I O

    2011-01-01

    The population of soil mesofauna in the basin of the small river subzone of the northern taiga (Karelia) has been investigated. It was shown that indexes of the number and mass of soil mesofauna in the landscape-ecological row ofbiogeocenosises are maximal in floodplain soils. The taxonomic composition and structure of domination of the soil mesofauna population depends on the location of biogeocenosis in the landscape: earthworms are dominants in riverine floodplain biogeocenosises, and larvae of elaterids and spiders prevail in the places outside of floodplains. The abundance of saprophytic invertebrates in floodplain biogeocenosises results in formation of humus of the mull type. A group of animals with mixed type of nutrition dominates in the places outside of floodplain soils that are related with humus of the moder-mor type. The population of rove beetles (Staphylinidae) allows the division of biogeocenosises into two groups according to their position in the landscape.

  12. Density, topography, and regional, tensile stresses: Gravity-driven extension of the northern Basin and range

    SciTech Connect

    Unruh, J.R. )

    1993-04-01

    It has long been recognized that regional topographic gradients may give rise to tectonic (non-lithostatic) stresses in the lithosphere (Artyushkov, 1973). The elevation of a buoyantly-uplifted region represents a balance between these stresses and the strength of the lithosphere. This study uses existing data on crustal and lithospheric structure in the western United States to test the hypothesis that the topographically high (1.5--2.2 km) northern Basin and Range is spreading under it own weight. Following England and Jackson (1989), the total deviatoric tensile force (Fl) in the northern Basin and Range (NBR) due to the regional high topography is the difference between the vertically-integrated lithostatic stress in the NBR and in western California. Using available velocity models for the crust and upper mantle, and empirically-derived velocity-density relationships, calculated values of Fl range between 1--3 [times] 10[sup 12] N/m. Assuming a visco-elastic rheology for the lithosphere, an average heat flow of 90 m W/m[sup 2], and a crustal thickness of 35 km, values of Fl ranging from 1--3 [times] 10[sup 12] N/m may result in horizontal extension rates of approximately 10[sup [minus]15]/s to 10[sup [minus]15]/s to 10[sup [minus]16]/s. This is comparable to the rate of seismically-released strain in the NBR, and to extension rates of 8--9 mm/yr across the region determined from geologic and geodetic data. These results imply that shear tractions on the base of the lithosphere from mantle convection are not necessary to explain NBR extension. In addition to driving active extension, the weight of the topographically high NBR may exert a compressive force on surrounding lowlands. If so, this may account for some of the active shortening in western California, and the state of horizontal compressive stress in the western Great Plains.

  13. Mapping and monitoring cheatgrass dieoff in rangelands of the Northern Great Basin, USA

    USGS Publications Warehouse

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

    2015-01-01

    Understanding cheatgrass (Bromus tectorum) dynamics in the Northern Great Basin rangelands, USA, is necessary to effectively manage the region’s lands. This study’s goal was to map and monitor cheatgrass performance to identify where and when cheatgrass dieoff occurred in the Northern Great Basin and to discover how this phenomenon was affected by climatic, topographic, and edaphic variables. We also examined how fire affected cheatgrass performance. Land managers and scientists are concerned by cheatgrass dieoff because it can increase land degradation, and its causes and effects are not fully known. To better understand the scope of cheatgrass dieoff, we developed multiple ecological models that integrated remote sensing data with geophysical and biophysical data. The models’ R2 ranged from 0.71 to 0.88, and their root mean squared errors (RMSEs) ranged from 3.07 to 6.95. Validation of dieoff data showed that 41% of pixels within independently developed dieoff polygons were accurately classified as dieoff, whereas 2% of pixels outside of dieoff polygons were classified as dieoff. Site potential, a long-term spatial average of cheatgrass cover, dominated the development of the cheatgrass performance model. Fire negatively affected cheatgrass performance 1 year postfire, but by the second year postfire performance exceeded prefire levels. The landscape-scale monitoring study presented in this paper helps increase knowledge about recent rangeland dynamics, including where cheatgrass dieoffs occurred and how cheatgrass responded to fire. This knowledge can help direct further investigation and/or guide land management activities that can capitalize on, or mitigate the effects of, cheatgrass dieoff.

  14. Bowser basin, northern British Columbia: Constraints on the timing of initial subsidence and Stikinia-North America terrane interactions

    NASA Astrophysics Data System (ADS)

    Ricketts, Brian D.; Evenchick, Carol A.; Anderson, Robert G.; Murphy, Donald C.

    1992-12-01

    Clastic strata composing the northern Bowser basin record the accretion of Stikinia to the composite western edge of the North American plate (Cache Creek-Quesnellia-Slide Mountain-Kootenay North America) in early Middle Jurassic time and the concomitant demise of the intervening Cache Creek ocean. Initial flexural subsidence of the northern Bowser basin, resulting from thrust loading of Cache Creek terrane on Stikinia, is represented by an organic-rich shale of Aalenian age (the Abou Formation of the Spatsizi Group). Coarse-grained sediment first appeared in early Bajocian time following uplift and subaerial exposure of Cache Creek rocks in the upper plate. Thus, the inception of the Bowser basin was Aalenian, rather than Bajocian, as believed by earlier workers. Aalenian southwest-vergent thrusting at the composite western edge of North America is also known from southern British Columbia, a coincidence that implicates collision with Stikinia in the south as a cause of that deformation.

  15. National Water-Quality Assessment Program: the Northern New England Basins study unit

    USGS Publications Warehouse

    Flanagan, Sarah M.; Robinson, Keith W.

    1994-01-01

    In 1991, the U.S. Geological Survey (USGS), U.S. Department of the Interior, began a full-scale National Water-Quality Assessment (NAWQA) program. The objectives of the NAWQA program are to describe the present and future water quality of large, representative parts of the United States's surface- and ground-water resources and to identify the primary natural and man-made factors that affect the quality of these resources. The final product of the program will be information that may be used by water-resource policy makers and managers at national, State, and local levels. The NAWQA program encompasses 60 study units. These units are delineated by hydrologic systems that include parts of most of the Nation's major river basins and aquifer systems. Study units range in size from 1,000 mi2 (square miles) to more than 60,000 mi2 and represent 60 to 70 percent of the Nation's water use and population served by public water supplies. The first group of 20 study-unit investigations began in 1991. A second group of 20 study-unit investigations began in 1994, which includes the Northern New England Basins study unit.

  16. Sequence stratigraphy and depositional facies of the Silurian-Devonian interval of the northern Permian basin

    SciTech Connect

    Canter, K.L.; Geesaman, R.C. ); Wheeler, D. )

    1992-04-01

    The Silurian and Devonian intervals of the northern Central Basin platform area of west Texas and southeastern New Mexico include the Fusselman, Wristen, and Thirtyone formations and the Woodford Shale. The carbonate-rich Fusselman, Wristen, and Thirtyone formations record a transition from ramp to platform deposition. Oolite grainstones of the lower Fusselman Formation were deposited in a ramp setting during an Upper Ordovician/Lower Silurian transgression. The overlying crinoid packstones and grainstones represent shoals that developed along a break in slope separating the evolving platform from a southward-dipping starved basin. By the close of Fusselman deposition, the platform was well developed, with shallow peridtidal mudstones and wackestones, and high-energy grainstones deposited as near-parallel facies tracts over the platform area. The platform system became fully developed during the deposition of the Wristen Formation. Porous dolomitic peridtidal and platform margin facies grade downdip into nonporous, limy and argillaceous open-shelf facies. Platform facies are typified by numerous shallowing-upward parasequences that terminated at subaerial exposure surfaces. The rocks of the Lower Devonian Thirtyone Formation were deposited as a wedge that onlaps the exposed Silurian platform margin. This formation contains a porous, chert-rich, lowstand deposit; a transgressive disconformity; and variably porous, grain-rich highstand deposits representing an overall sea level rise. A major unconformity marks the contact between the karsted upper surface of the Thirtyone Formation and the overlying organic-rich, anoxic Woodford Shale.

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

    PubMed

    Li, Chengcheng; Gao, Xubo; Wang, Yanxin

    2015-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-03-01

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

  19. Hypothetical southeast Pacific continent revisited New evidence from the middle Paleozoic basins of northern Chile

    NASA Astrophysics Data System (ADS)

    Bahlburg, Heinrich

    1993-10-01

    The truncation of orogenic trends at the modern Chilean coast, paleocurrent indicators, and facies distributions indicating the derivation of sediment from sialic sources in the present-day Pacific have suggested to students of the Paleozoic foundation of the Andes that a "south east Pacific continent" may have been located oceanward of the present margin in Paleozoic time. These features are well represented in the middle Paleozoic siliciclastic platform-deeper basin system in northern Chile. Furthermore, the Middle Devonian platform sections contain brachiopods both of Malvinokaffric and Eastern Americas realm affinity. Sedimentological and tectonic features are consistent with the evolution of the basin in a Devonian and early Carboniferous extensional regime, which was succeeded by the inception of subduction by oblique convergence in the late Carboniferous. The extensional regime was possibly governed by the clockwise motion of Laurentia along the proto-Andean margin, as recently proposed by Ian Dalziel; subduction of Pacific oceanic crust then began in the wake of Laurentia moving toward its Permian position in the Pangea supercontinent.

  20. The spatial and temporal variability of groundwater recharge in a forested basin in northern Wisconsin

    USGS Publications Warehouse

    Dripps, W.R.; Bradbury, K.R.

    2010-01-01

    Recharge varies spatially and temporally as it depends on a wide variety of factors (e.g. vegetation, precipitation, climate, topography, geology, and soil type), making it one of the most difficult, complex, and uncertain hydrologic parameters to quantify. Despite its inherent variability, groundwater modellers, planners, and policy makers often ignore recharge variability and assume a single average recharge value for an entire watershed. Relatively few attempts have been made to quantify or incorporate spatial and temporal recharge variability into water resource planning or groundwater modelling efforts. In this study, a simple, daily soil-water balance model was developed and used to estimate the spatial and temporal distribution of groundwater recharge of the Trout Lake basin of northern Wisconsin for 1996-2000 as a means to quantify recharge variability. For the 5 years of study, annual recharge varied spatially by as much as 18 cm across the basin; vegetation was the predominant control on this variability. Recharge also varied temporally with a threefold annual difference over the 5-year period. Intra-annually, recharge was limited to a few isolated events each year and exhibited a distinct seasonal pattern. The results suggest that ignoring recharge variability may not only be inappropriate, but also, depending on the application, may invalidate model results and predictions for regional and local water budget calculations, water resource management, nutrient cycling, and contaminant transport studies. Recharge is spatially and temporally variable, and should be modelled as such. Copyright ?? 2009 John Wiley & Sons, Ltd.

  1. Provenance and tectonic-paleogeographic evolution: Constraints from detrital zircon U-Pb ages of Late Triassic-Early Jurassic deposits in the northern Sichuan basin, central China

    NASA Astrophysics Data System (ADS)

    Shao, Tongbin; Cheng, Nanfei; Song, Maoshuang

    2016-09-01

    U-Pb ages of 290 new detrital zircons from five Late Triassic-Early Jurassic sandstone samples in the northern Sichuan basin, along with other geological data, are used to constrain the sediment provenance and evaluate tectonic-paleogeographic evolution for the adjacent orogens through/from which these sediments were potentially derived. The Upper Triassic depocenter was located at the front of the Longmen Shan belt, and sediments in the western, southern and eastern Sichuan basin shared the southern North China block (NCB) and Qinling belt with the eastern Songpan-Ganzi terrane of Middle-Upper Triassic via the Longmen Shan belt, whereas the northern part of the basin was fed by dominant South Qinling belt (SQB) and northern Yangtze block and possibly subordinate southern NCB. Also, the youngest population in the northern Sichuan basin has a slightly younger age peak (∼235 Ma) than those (∼270 Ma) in other parts of the basin. During the Early Jurassic, the depocenter was still at the front of the Longmen Shan belt but only northern regions (e.g., SQB and northern Yangtze block) fed the basin. The northern Sichuan basin received less sediments from the southern NCB and more from the SQB and northern Yangtze block during the Early Jurassic than during the Late Triassic. The middle Mesoproterozoic detrital zircons, which likely originated from the North Qinling belt and northern Yangtze block where rocks with these zircons may be unexposed, occur more widely in the Lower Jurassic than in the Upper Triassic. These facts suggest that from the Late Triassic to Early Jurassic, it was increasingly difficult for sediments to transport from the NCB into the northern Sichuan basin and the provenance transferred progressively from the southern NCB to both the SQB and northern Yangtze block, implying the continuous South China block-NCB collision during that time.

  2. Spatial distribution of pelagic fish larvae in the northern main basin of Lake Huron

    USGS Publications Warehouse

    Roseman, Edward F.; O'Brien, Timothy P.

    2013-01-01

    Larval fish occurrence in inshore and offshore zones in the northern main basin of Lake Huron was assessed during 2007 as part of a larger ecological examination of Lake Huron foodwebs and habitats. Day and night collections using neuston and conical nets at inshore (1.5–15 m depths) and offshore (37 and 91 m depths) locations at De Tour and Hammond Bay to assess the abundance, phenology, and spatial distribution of pelagic ichthyoplankton during spring and early summer were made. In general, densities of larval fishes were higher at De Tour than Hammond Bay during daytime neuston net collections, with the exception of Longnose Sucker, which were only collected at Hammond Bay. Lake Whitefish, Burbot, and Rainbow Smelt dominated inshore catches in early spring with Cisco, Deepwater Sculpin, Emerald Shiner, Bloater, Slimy Sculpin, Ninespine Stickleback, and Yellow Perch larvae also collected. Nighttime nearshore and offshore sampling revealed that Rainbow Smelt and Burbot larvae were present in relatively high abundances compared to inshore densities. Concentrations of larvae of deepwater demersal fishes such as Lake Whitefish and Deepwater Sculpin suggest that inshore zones in northern Lake Huron are important nursery habitats emphasizing a critical production and recruitment linkage between inshore and deepwater zones.

  3. Mictomys borealis (northern bog lemming) and the Wisconsin paleoecology of the east-central Great Basin

    NASA Astrophysics Data System (ADS)

    Mead, Jim I.; Bell, Christopher J.; Murray, Lyndon K.

    1992-03-01

    Teeth of northern bog lemming, Mictomys borealis, are reported from Cathedral and Smith Creek caves and represent the first Wisconsin remains of the genus from the Great Basin. Specimens from Cathedral Cave, Snake Range, are associated with U-series ages of 24,000 to 15,000 yr B.P. Previous work with pollen and packrat middens, dating to the same age as the Mictomys, indicate that Smith Creek Canyon contained a riparian, locally mesic community, including Picea engelmannii (spruce), Betula sp. (birch), Cercocarpus sp. (mountain mahogany), and Artemisia sp. (sagebrush) among other species. Exposed canyon slopes and the adjacent valley apparently contained a more xeric steppe community including sagebrush and Chenopodiineae species; rocky outcrop permitted Pinus flexilis (limber pine) and P. longaeva (bristlecone pine) to grow adjacent to Lake Bonneville or low in the canyon. The region apparently experienced a dry climate (not necessarily drier than today); however, Smith Creek Canyon was fed by glacial meltwater from Mt. Moriah. The northern bog lemming probably lived only in the riparian community and possibly on the north-facing slope below Cathedral Cave. Few canyons of the Snake Range would have had the unusually mesic conditions found in Smith Creek Canyon.

  4. Assessing groundwater recharge mechanisms in the Pampa del Tamarugal Basin of northern Chile's Atacama Desert

    NASA Astrophysics Data System (ADS)

    Jayne, R., Jr.; Pollyea, R.; Dodd, J. P.; Olson, E. J.; Swanson, S.

    2015-12-01

    The hyper-arid Atacama Desert in northern Chile is one of the driest inhabited places on Earth receiving little to no rain (<5 mm/yr). Within the Tarapacá Region of the Atacama Desert, the Pampa del Tamarugal Aquifer (PTA) is the primary source of water for agriculture, industry, mining, and residential uses. The PTA covers 5,000 km2, and is located in the Pampa del Tamarugal Basin, which is situated between the Andes and the Coastal Cordillera, and is filled with ~1700m of Miocene and younger sediments. The source of recharge for the PTA originates as precipitation in the high Andes, which can receive up to 400 mm/yr of precipitation; however, the mechanisms and magnitude of recharge to the PTA are still poorly understood. Here, we present a regional scale, non-isothermal 2-D numerical groundwater model is developed to analyze the time scales and geological controls on fluid flow paths recharging the PTA. Results from this work suggest that (1) both shallow groundwater flow and deep (>1km) hydrothermal fluid circulation are responsible for recharging the PTA; (2) topography and geothermal gradients are the main driving factors for regional groundwater flow; (3) the Altos de Pica member 4, an ignimbrite layer in the sedimentary basin controls both heat and fluid flow in the western part of the basin, this is evident due to the presence of convection cells and meteoric water upwelling and presenting itself as surface water (salars); and (4) it takes meteoric water 100,000 years to travel from the high Andes to reach Pica and 1,000,000 years for salar formation. In addition, this work provides a theoretical basis for the spatial distribution of highly alkaline surface water bodies, known as salars in the western Atacama Desert.

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

    USGS Publications Warehouse

    Preston, Todd M.; Kim, Kevin

    2016-01-01

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

  6. Potential hydrologic effects of mining in the Humboldt River Basin, northern Nevada

    USGS Publications Warehouse

    Crompton, E. James

    1995-01-01

    This report provides a general assessment of effects that the current and potential mining activities during the next 5 years may have on the water resources in each of the 34 hydrographic areas in the Humboldt River Basin of northern Nevada. Nearly 40 active gold mines are operating in the basin; of these, 15 are large-scale, open-pit mines. The potential effects of mining were assessed for seven water-resource characteristics or features at various distances from the mining operations. These characteristics are ground-water levels, springs, perennial streams, shallow ground-water areas, sediment transport, agricultural irrigation, and fish and wildlife habitat. The characteristics and features were evaluated at two distances; local (within 2 miles of the operation) and areal (from 2 to 6 miles away from the operation). Additionally, ground-water levels were evaluated at the regional distances: local (with 2 miles of the operation) and areal (from 2 to 6 miles away from the operation). Additionally, ground-water levels were levels were evaluated at the regional distance (more than 6 miles away from the operation). A numerical ranking scale, ranging from a large change expected to no change expected, was developed for each characteristic and feature. For each hydrographic area in the basin, a single value was assigned for each characteristic at each distance. This value represents the greatest change expected to occur in that hydrographic area. The study results show that the greatest changes are expected in two hydro- graphic areas: Pumpernickel Valley and Kelly Creek Area.

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

    PubMed

    Preston, Todd M; Kim, Kevin

    2016-10-01

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

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

    PubMed

    Theuring, Philipp; Collins, Adrian L; Rode, Michael

    2015-09-01

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

  9. Northern Basin and Range Ecoregion: Chapter 23 in Status and trends of land change in the Western United States--1973 to 2000

    USGS Publications Warehouse

    Soulard, Christopher E.

    2012-01-01

    The Northern Basin and Range Ecoregion (Omernik, 1987; U.S. Environmental Protection Agency, 1997) is located in eastern Oregon (58.7 percent), northern Nevada (20.6 percent), southwestern Idaho (14.8 percent), and northeastern California (5.9 percent), encompassing the northern extent of the hydrographic Great Basin (Grayson, 1993). The ecoregion, which covers approximately 110,039 km² (42,486 mi²) of land, is bordered on the west by the Eastern Cascades Slopes and Foothills and the Sierra Nevada Ecoregions, on the north by the Blue Mountains and the Snake River Basin Ecoregions, and on the south by the Central Basin and Range Ecoregion (fig. 1). Much like the other Basin and Range ecoregions in the western United States (for example, Central Basin and Range, Mojave Basin and Range, and Sonoran Basin and Range Ecoregions), the Northern Basin and Range Ecoregion is characterized by basin-and-range topography. The ecoregion contains several wide basins bordered by scattered low mountains. Big sagebrush (Artemisia tridentata), the predominant vegetation, is intermixed with grasslands. Despite regional aridity, natural springs and spring-fed wetlands are scattered around the landscape, sustaining much of the region’s wildlife (Oregon Department of State Lands, 2000).

  10. Seismic Stratigraphy around Continent-Ocean Boundary in the NW Sub-basin, Northern South China Sea

    NASA Astrophysics Data System (ADS)

    Chang, S. P.; Liu, C. S.; Hsu, H. H.; Chang, J. H.

    2015-12-01

    The northern continental margin of the South China Sea (SCS) is a passive margin, and have experienced rifting and seafloor spreading. From continental shelf to deep sea basin, the nature of the crust gradually changes from continental crust to oceanic crust. Many studies use a term "continent-ocean boundary (COB)", to describe the boundary between these two kinds of crust. This boundary is roughly located along the boundary between slope and deep sea basin, and roughly parallels to the 3000 m isobath in the northern SCS. This study analyzes many multiple channel seismic reflection profiles in the northern continental margin of the SCS, and has identified an angular unconformity between the slope and deep sea basin deposits at the COB in the NW sub-basin area. This unconformity extends from continental slope to NW sub-basin near the COB. Strata beneath the unconformity downlap to the basement. Furthermore, there is a strong reflector beneath the unconformity, and this strong reflector, called "Tom", represents a hiatus which was recognized by biostratigraphic analyses from Site 1148 of ODP Leg 184. The strata between the unconformity surface and reflector Tom pinch toward deep sea basin, and then the unconformity and reflector Tom merge into one reflector. Therefore, the unconformity might be an erosional surface. The strata covered the unconformity onlap the unconformity. Some portions of the COB have intrusions forming basement high, and the unconformity and strata are coherent with basement relief. The unconformity has been interpreted as a normal fault in some previous studies, but our study distinguishes it as an erosional surface. Besides, some previous studies consider the bottom of the sedimentary layers in the NW sub-basin as the onset of depositing deep sea environment, and suggested that it is related to the onset of seafloor spreading. However, we interpret the angular unconformity as the onset of deep sea environment, and it differs from the onset of

  11. Landsat investigations of the northern Paradox basin, Utah and Colorado: implications for radioactive waste emplacement

    USGS Publications Warehouse

    Friedman, Jules D.; Simpson, Shirley L.

    1978-01-01

    The first stages of a remote-sensing project on the Paradox basin, part of the USGS (U.S. Geological Survey) radioactive waste-emplacement program, consisted of a review and selection of the best available satellite scanner images to use in geomorphologic and tectonic investigations of the region. High-quality Landsat images in several spectral bands (E-2260-17124 and E-5165-17030), taken under low sun angle October 9 and 10, 1975, were processed via computer for planimetric rectification, histogram analysis, linear transformation of radiance values, and edge enhancement. A lineament map of the northern Paradox basin was subsequently compiled at 1:400,000 using the enhanced Landsat base. Numerous previously unmapped northeast-trending lineaments between the Green River and Yellowcat dome; confirmatory detail on the structural control of major segments of the Colorado, Gunnison, and Dolores Rivers; and new evidence for late Phanerozoic reactivation of Precambrian basement structures are among the new contributions to the tectonics of the region. Lineament trends appear to be compatible with the postulated Colorado lineament zone, with geophysical potential-field anomalies, and with a northeast-trending basement fault pattern. Combined Landsat, geologic, and geophysical field evidence for this interpretation includes the sinuousity of the composite Salt Valley anticline, the transection of the Moab-Spanish Valley anticline on its southeastern end by northeast-striking faults, and possible transection (?) of the Moab diapir. Similarly, northeast-trending lineaments in Cottonwood Canyon and elsewhere are interpreted as manifestations of structures associated with northeasterly trends in the magnetic and gravity fields of the La Sal Mountains region. Other long northwesterly lineaments near the western termination of the Ryan Creek fault zone. may be associated with the fault zone separating the Uncompahgre horst uplift from the Paradox basin. Implications of the

  12. Status and understanding of groundwater quality in the northern San Joaquin Basin, 2005

    USGS Publications Warehouse

    Bennett, George L.; Fram, Miranda S.; Belitz, Kenneth; Jurgens, Bryant C.

    2010-01-01

    Groundwater quality in the 2,079 square mile Northern San Joaquin Basin (Northern San Joaquin) study unit was investigated from December 2004 through February 2005 as part of the Priority Basin Project of the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The GAMA Priority Basin Project was developed in response to the Groundwater Quality Monitoring Act of 2001 that was passed by the State of California and is being conducted by the California State Water Resources Control Board in collaboration with the U.S. Geological Survey and the Lawrence Livermore National Laboratory. The Northern San Joaquin study unit was the third study unit to be designed and sampled as part of the Priority Basin Project. Results of the study provide a spatially unbiased assessment of the quality of raw (untreated) groundwater, as well as a statistically consistent basis for comparing water quality throughout California. Samples were collected from 61 wells in parts of Alameda, Amador, Calaveras, Contra Costa, San Joaquin, and Stanislaus Counties; 51 of the wells were selected using a spatially distributed, randomized grid-based approach to provide statistical representation of the study area (grid wells), and 10 of the wells were sampled to increase spatial density and provide additional information for the evaluation of water chemistry in the study unit (understanding/flowpath wells). The primary aquifer systems (hereinafter, primary aquifers) assessed in this study are defined by the depth intervals of the wells in the California Department of Public Health database for each study unit. The quality of groundwater in shallow or deep water-bearing zones may differ from quality of groundwater in the primary aquifers; shallow groundwater may be more vulnerable to contamination from the surface. Two types of assessments were made: (1) status, assessment of the current quality of the groundwater resource; and (2) understanding, identification of the natural and human factors

  13. Highly extended terrains, lateral segmentation of the substratum, and basin development: The middle-late Miocene Radicondoli Basin (inner northern Apennines, Italy)

    NASA Astrophysics Data System (ADS)

    Brogi, Andrea; Liotta, Domenico

    2008-09-01

    This paper deals with the evolution of sedimentary basins not delimited by normal faults, with a substratum characterized by an upward concave shape and with infilling sediments synclinally deformed. We describe the middle-late Miocene Radicondoli Basin, representing an example of such bowl-shaped basins. Its tectonic origin is controversial, being related both to compression and extension; these opposite interpretations bear significant consequences on the geodynamic context in which the inner northern Apennines developed during the middle-late Miocene. The results of our structural studies, carried out in the substratum and infilling sediments, indicate that the Radicondoli Basin is an example of a hanging wall basin developed in an extensional setting. Extensional tectonics determined the lateral segmentation of the substratum competent levels (i.e., Tuscan Nappe and Verrucano Group) and the consequent collapse of overlying less competent levels (i.e., the Ligurian units) with the formation of a bowl-shaped tectonic depression. Here, the syntectonic sediments (Serravallian-late Messinian) are deformed in a large syncline, characterized by minor gravity-driven folds, with vergences toward the depocenter and traces of their axial planes parallel to the basin margins. This paper highlights the role of the competence contrast during the postcollisional tectonic evolution and the influence of substratum lateral segmentation for the accommodation of syntectonic sediments.

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

    USGS Publications Warehouse

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

    2011-01-01

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

  15. Currents at the sills bounding Delfin Basin in the northern Gulf of California

    NASA Astrophysics Data System (ADS)

    Lopez, M.; Candela, J.

    2013-05-01

    One-year-long currents at the two sills bounding Delfin basin (maximum depth ˜900 m), are analyzed. The Delfin (DEL) sill (˜400 m depth) has the largest mean velocities near the bottom in an overflow that discharges water into the Delfin Basin (roughly towards the head of the gulf), whereas the Ballenas Channel (BC) sill (˜600 m depth) has the largest mean velocities close to the surface which also flow towards the head of the gulf. The energy of the subinertial current fluctuations is also quite different. Most of the energy at the DEL sill is concentrated in the lowest frequencies (periods > 15 days). In the case of the BC sill, the spectra are not red and much of the energy is concentrated at periods ≤ 15 days except close to the surface, where most the energy is also concentrated in the lowest frequencies associated with the current fluctuations of the mean near-surface current towards the head of the gulf. Near-bottom current fluctuations towards the head of the gulf at the overflow of the DEL sill are well correlated with intermediate and deeper currents towards the mouth of the gulf, as well as with surface currents towards the head of the gulf at the BC sill for periods ≥ 20 days. Transport of the overflow also has the largest coherences with near-surface currents at the BC sill for periods ≥ 20 days, but there is also significant coherence with deeper currents at the same low frequencies. The relationship between the overflow and the exchange at the BC sill is also clearly borne out by the first empirical mode of currents at both locations. This is interpreted as part of the exchange of the northern gulf by which fluctuations of the near-bottom flow into the deepest basins are compensated by fluctuations of the near-surface flow out of the same basins. In addition, near-bottom transport and currents at the DEL sill are coherent with deep currents at the CB sill at the shorter periods of 10 and 3.2 days. At these periods, there is also good

  16. Late Cenozoic lacustrine and climatic environments at Tule Lake, northern Great Basin, USA

    USGS Publications Warehouse

    Platt, Bradbury J.

    1992-01-01

    Cores of lake sediment to a depth of 334 m in the town of Tulelake, Siskiyou County, northern California, document the late Cenozoic paleolimnologic and paleoclimatic history of the northwestern edge of the Great Basin. The cores have been dated by radiometric, tephrochronologic and paleomagnetic analyses. Lacustrine diatoms are abundant throughout the record and document a nearly continuous paleolimnologic history of the Tule Lake basin for the last 3 Myr. During most of this time, this basin (Tule Lake) was a relatively deep, extensive lake. Except for a drier (and cooler?) interval recorded by Fragilaria species about 2.4 Ma, the Pliocene is characterized by a dominance of planktonic Aulacoseira solida implying a warm monomictic lake under a climatic regime of low seasonality. Much of the Pleistocene is dominated by Stephanodiscus and Fragilaria species suggesting a cooler, often drier, and highly variable climate. Benthic diatoms typical of alkaline-enriched saline waters commonly appear after 1.0 Ma, and tephrochronology indicates slow deposition and possible hiatuses between about 0.6 and 0.2 Ma. The chronology of even-numbered oxygen isotope stages approximately matches fluctuations in the abundance of Fragilaria since 800 ka indicating that glacial periods were expressed as drier environments at Tule Lake. Glacial and interglacial environments since 150 ka were distinct from, and more variable than, those occurring earlier. The last full glacial period was very dry, but shortly thereafter Tule Lake became a deep, cool lacustrine system indicating a substantial increase in precipitation. Aulacoseira ambigua characterized the latest glacial and Holocene record of Tule Lake. Its distribution indicates that warmer and wetter climates began about 15 ka in this part of the Great Basin. Diatom concentration fluctuates at 41 000 year intervals between 3.0 and 2.5 Ma and at approximately 100 000 year intervals after 1.0 Ma. In the late Pliocene and early Pleistocene

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

    PubMed Central

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

    2016-01-01

    The Lhasa terrane is a key region for understanding the paleoelevation of the southern Tibetan Plateau after India-Asia collision. The Gerze Basin, located in the northern part of the Lhasa terrane, is a shortening-related basin. We discovered Lagena laevis (Bandy) fossils in upper Eocene strata of the Gerze Basin. This type of foraminifera is associated with lagoon and estuarine environments, indicating that the northern part of the Lhasa terrane was near sea level during the late Eocene. We speculate that these foraminifera were transported inland by storm surges to low elevation freshwater lakes during times of marine transgressions. This inference is consistent with the relatively positive δ18O values in carbonate from the same deposits that indicate low palaeoelevations close to sea level. Considering the palaeoelevation results from the nearby Oligocene basins at a similar latitude and the volcanic history of the Lhasa terrane, we infer that large-magnitude surface uplift of the northern Lhasa terrane occurred between late Eocene and late Oligocene time. PMID:27272610

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

    PubMed

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

    2013-01-01

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

  19. Oligocene-Miocene Mammalian Fossils from Hongyazi Basin and Its Bearing on Tectonics of Danghe Nanshan in Northern Tibetan Plateau

    PubMed Central

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

    2013-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Mourgues, Francisco Amaro

    2004-09-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

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

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

    USGS Publications Warehouse

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

    2004-01-01

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

  3. Late cenozoic lacustrine and climatic environments at Tule Lake, northern Great Basin, USA

    SciTech Connect

    Bradbury, J.P.

    1992-01-01

    Cores of lake sediment to a depth of 334 m in the town of Tulelake, northern California, document the late Cenozic paleolimnologic and paleoclimatic history of the northwestern Great Basin. Lacustrine diatoms are abundant throughout the record documenting a nearly continuous paleolimnologic history of the Tule Lake basin. Except for a drier (and cooler?) interval recorded by Fragilaria species about 2.4 Ma, the Pliocene is characterized by a dominance of planktonic Aulacoseira solida implying a warm monomictic lake under a climatic regime of low seasonality. Much of the Pleistocene is dominated by Stephanodiscus and Fragilaria species suggesting a cooler, drier, and highly variable climate. Benthic diatoms typical of alkaline-enriched saline waters commonly appear after 1.0 Ma, and tephrochronology indicates slow deposition and possible hiatuses between about 0.6 and 0.2 Ma. The chronology of even-numbered oxygen isotope stages approximately matches fluctuations in the abundance of Fragilaria since 800 ka indicating that glacial periods were drier environments at Tule Lake. Glacial and interglacial environments since 150 ka were distinct from, and more variable than, those occurring earlier. The last full glacial period was very dry, but shortly Tule Lake became a deep, cool lacustrine system indicating a substantial increase in precipitation. Aulacoseira ambigua characterized the latest glacial and Holocene record of Tule Lake, indicating that warmer and wetter climates began about 15 ka. Diatom concentration fluctuates at 41000 year intervals between 3.0 and 2.5 Ma and at approximately 100000 year intervals after 1.0 Ma. In the late Pliocene and early Pleistocene, Aulacoseira solida percentages wax and wane in an approximately 400000 year cycle. The possible response of Tule Lake diatom communities to orbitally-induced insolation cycles underscores the importance of this record for the study of late Cenozoic paleoclimate change. 41 refs., 8 figs.

  4. Origin and geochemical evolution of groundwater in a closed-basin clayey aquitard, Northern Mexico

    NASA Astrophysics Data System (ADS)

    Ortega-Guerrero, Adrián

    2003-12-01

    Groundwater flow cross-sectional modeling in combination with major ion and trace element chemistry, stable isotopes of water ( 18O and 2H) and geochemical modeling were used to investigate the origin and evolution of groundwater in a Quaternary lacustrine clay-rich aquitard in the closed basin of the 'La Laguna Region', Northern Mexico. This study pertains to the Viesca Lake, one of a series of ephemeral ancient lakes that existed in this basin until the early 1900s. The Viesca aquitard overlies a regional marine Mesozoic sequence that outcrops in the surrounding mountains. Groundwater samples were collected from springs, pumping wells in a carbonate aquifer and from former industrial production wells in the aquitard. Numerical results indicate a classical gravity flow system, where the carbonate aquifer discharged about 90% of the groundwater, as springs, that fed the former Viesca Lake. Isotope content of groundwater, in the carbonate aquifer, shows that groundwater has a local meteoric origin; and its chemical evolution is mainly associated to progressive dissolution of gypsum and oxidation of pyrite along the flow paths. In contrast, groundwater in the aquitard presented enrichment of heavy isotopes 2H and 18O, indicating that this water resulted from the evaporation of the carbonate groundwater aquifer. The maximum concentrations of sulfate (77,700 mg L -1), chloride (45,400 mg L -1) and sodium (45,000 mg L -1) in the groundwater from the aquitard were between three and four orders of magnitude greater than the fresh groundwater. Sulfate behaved as a conservative ion, contrasting with concentration of sulfate in groundwater from other aquitards in the world; which is usually reduced. Chemical patterns and enrichment of stable isotopes in groundwater from the aquitard follow general evaporation trends observed for other closed or semi-closed basins worldwide. Redox related parameters (NO 3-N, NH 4+, Mn 2+, total Fe and TOC) and redox-sensitive trace elements

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

    USGS Publications Warehouse

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

    2012-01-01

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

  6. Preliminary study of the uranium potential of the northern part of the Durham Triassic Basin, North Carolina

    SciTech Connect

    Harris, W.B.; Thayer, P.A.

    1981-09-01

    This report presents results of a four-channel spectrometric survey of the northern part of the Durham Triassic basin and adjacent Piedmont, North Carolina. Gamma-ray spectrometric measurements were obtained at 112 localities from 136 different lithologies. The nominal sampling density in the Durham Basin is one site per 2 mi/sup 2/. Surface radiometric surveys reveal no anomalous radioactivity in the northern part of the Durham Basin. Uranium concentrations in Triassic rocks are from 0.6 to 9.7 ppM and average 2.9 ppM. Mudrocks contain from 1.3 to 9.7 ppM, and the average is 4.5 ppM. Sandstones contain from 0.6 to 8.8 ppM, and the average is 2.5 ppM. Fanglomerates contain the lowest concentrations of uranium, from 1.4 to 2.0 ppM, for an average of 1.8 ppM. Uranium/thorium ratios average 0.27 for Triassic rocks and are from 0.04 to 1.85. The mean log uranium/log thorium for Triassic rocks is 0.37. Mudrock has the highest average uranium/thorium ratio (0.32), and the range is 0.09 to 0.66. Sandstones have an average uranium/thorium ratio of 0.26, and the range is 0.04 to 1.85. Fanglomerates have the lowest range uranium/thorium ratio (0.19), and the range is 0.12 to 0.19. On the basis of surface radiometric surveys and geologic studies, it is believed that sedimentary strata in the northern part of the Durham Basin are poor targets for further uranium exploration. This conclusion is based on the lack of favorable characteristics commonly present in fluvial uranium deposits. Among these are: (1) carbonaceous material is absent in Triassic rocks of the northern basin, (2) indicators of a reduzate facies in sandstones are not present, and (3) no tuffaceous beds are associated with sediments in the northern Durham Basin.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  8. Neogene Basin Evolution Along the Northern Flank of the Papuan Peninsula, Goodenough Bay, Eastern Papua New Guinea

    NASA Astrophysics Data System (ADS)

    Horton, B. K.; Gillis, R. J.; Mann, P.

    2009-12-01

    Although large-magnitude extension in the Woodlark Rift of eastern Papua New Guinea (PNG) and the D’Entrecasteaux Islands has been addressed through previous research on the late Cenozoic structure and cooling history of metamorphic domes, few studies have evaluated the exhumational record contained within adjacent sedimentary basins. Onshore exposures of Neogene basin fill in PNG along the northern flank of the Papuan peninsula (east of the Dayman metamorphic dome and west-southwest of the domes of the D’Entrecasteaux Islands) provide a record of basin evolution prior to and during growth of the active spreading center that defines the boundary between the Australian plate and Woodlark microplate. Along the northern margin of the Papuan peninsula, a collection of lithofacies associations consisting of sandstone and subordinate conglomerate and mudstone represent deposition in bottomset, foreset, and topset subenvironments in a series of marine Gilbert-type deltas. Internal angular unconformities within the basin-fill succession indicate slope instability likely related to syndepositional deformation. This deformation is attributed to principally down-to-the north motion along extensional and strike-slip structures bordering the northern margin of Papuan peninsula, notably the ESE-striking Goodenough fault zone. Small-scale folding is interpreted as the product of late Miocene to Quaternary fault-related folding in an extensional setting, although we cannot rule out possible contraction coeval with significant collision-related shortening on the southern flank of the Papuan peninsula within the south-directed Papuan fold-thrust belt. Differences in sandstone petrographic results for the northern margin of the Papuan peninsula and the smaller Vogel peninsula suggest a multiphase history of basin evolution, with early Neogene subsidence of uncertain origin and late Neogene subsidence linked to regional extension. The timing of basin evolution will be assessed

  9. Biostratigraphy, sedimentology and paleoenvironments of the northern Danube Basin: Ratkovce 1 well case study

    NASA Astrophysics Data System (ADS)

    Rybár, Samuel; Halásová, Eva; Hudáčková, Natália; Kováč, Michal; Kováčová, Marianna; Šarinová, Katarína; Šujan, Michal

    2015-02-01

    The Ratkovce 1 well, drilled in the Blatné depocenter of the northern Danube Basin penetrated the Miocene sedimentary record with a total thickness of 2000 m. Biostratigraphically, the NN4, NN5 and NN6 Zones of calcareous nannoplankton were documented; CPN7 and CPN8 foraminifer Zones (N9, 10, 11 of the global foraminiferal zonation; and MMi4a; MMi5 and MMi6 of the Mediterranean foraminiferal zonation were recognized. Sedimentology was based on description of well core material, and together with SP and RT logs, used to characterize paleoenvironmental conditions of the deposition. Five sedimentary facies were reconstructed: (1) fan-delta to onshore environment which developed during the Lower Badenian; (2) followed by the Lower Badenian proximal slope gravity currents sediments; (3) distal slope turbidites were deposited in the Lower and Upper Badenian; (4) at the very end of the Upper Badenian and during the Sarmatian a coastal plain of normal marine to brackish environment developed; (5) sedimentation finished with the Pannonian-Pliocene shallow lacustrine to alluvial plain deposits. The provenance analysis records that the sediment of the well-cores was derived from crystalline basement granitoides and gneisses and from the Permian to Lower Cretaceous sedimentary cover and nappe units of the Western Carpathians and the Eastern Alps. Moreover, the Lower Badenian volcanism was an important source of sediments in the lower part of the sequence.

  10. Lithologic variations and diagenesis of Lower Cretaceous Muddy Formation in northern Powder River basin, Wyoming

    SciTech Connect

    Walker, A.L.; Patterson, P.E.

    1986-08-01

    Regional facies studies show that sandstones in the Muddy Formation, northern Powder River basin, were deposited in fluvial and nearshore marine paleoenvironments. Most sandstones of the fluvial facies contain only minor amounts of clay matrix and are classified as quartzarenite or sublitharenite, whereas those of the shoreface facies contain appreciable clay and are classified as litharenite or arkose. The arkoses are concentrated along a narrow belt that trends northeastward, parallel to the inferred paleoshoreline. Both the fluvial and shoreface sandstones have been variably affected by postdepositional alteration. During early stages of diagenesis, matrix clay was formed predominantly within the shoreface sandstones, owing mainly to alteration of volcanic material. Later, quartz overgrowths and calcite cement were precipitated within the remaining pore spaces in both fluvial and shoreface sandstones. Calcite also replaced detrital framework grains and some of the previously formed matrix clay. During intermediate diagenetic stages, detrital feldspar grains, particularly those in the arkosic shoreface sandstones, were replaced by albite, which characteristically lacks twinning or displays distinctive chessboard texture. Microprobe analyses indicate that both forms are essentially pure albite. During later stages of diagenesis, following maximum burial, much of the calcite was dissolved, producing secondary porosity. Inasmuch as the calcite was precipitated early, i.e., prior to significant compaction, and inasmuch as it replaced both framework grains and authigenic matrix clay, the secondary pores exhibit a relatively high level of interconnection. It is this secondary porosity that has contributed to the migration and storage of hydrocarbons in the Muddy Formation.

  11. New palynological data from Karoo sediments, Mana Pools basin, northern Zimbabwe

    NASA Astrophysics Data System (ADS)

    d'Engelbronner, E. R.

    1996-07-01

    The palynological associations of 16 Karoo samples, collected in the Mana Pools basin, Northern Zimbabwe, were studied, and four zonal assemblages can be recognized. Assemblage I (Kondo Pools Formation) is dominated by monosaccate pollen grains and diverse alete bisaccate pollen grains occur frequently. Important but rare marker genera include Limitisporites, Vittatina and Weylandites. These indicate a middle to late Early Permian age (e.g. Late Sakmarian to Early Artinskian). The palynological assemblage, derived from the Massive Sandstone Member, Angwa Sandstone Formation, is characterized by a small number of smooth and apiculate spores, but is lacking any age significant marker taxa. Assemblages II and III, both from the Alternations Member (Angwa Sandstone Formation), and Assemblage IV (Pebbly Arkose Formation) are dominated by alete bisaccate and multitaeniate pollen grains. The rare occurrence of Vittatina, Weylandites lucifer and Guttulapollenites hannonicus indicates a Late Permian to Early Triassic age for Assemblage II. Based on sedimentological data and literature, a preliminary age of Early Triassic (Induan) can be given. A range from latest Fassanian (Ladinian) to Lacian (Norian) for Assemblage III is indicated by the occurrence of Asseretospora gyrata, Cadargasporites senectus, Eucommiidites, Infernopollenites, Minutosaccus crenulatus, Retisulcites perforatus and Samaropollenites speciosus. Small amounts of Asseretospora gyrata, Cadargasporites senectus, Cycadopites, Microcachryidites and Minutosaccus crenulatus indicate a slightly larger age range for Assemblage IV (e.g. Carnien to Rhaetian).

  12. Thermal maturity of northern Appalachian Basin Devonian shales: Insights from sterane and terpane biomarkers

    USGS Publications Warehouse

    Hackley, Paul C.; Ryder, Robert T.; Trippi, Michael H.; Alimi, Hossein

    2013-01-01

    To better estimate thermal maturity of Devonian shales in the northern Appalachian Basin, eleven samples of Marcellus and Huron Shale were characterized via multiple analytical techniques. Vitrinite reflectance, Rock–Eval pyrolysis, gas chromatography (GC) of whole rock extracts, and GC–mass spectrometry (GCMS) of extract saturate fractions were evaluated on three transects that lie across previously documented regional thermal maturity isolines. Results from vitrinite reflectance suggest that most samples are immature with respect to hydrocarbon generation. However, bulk geochemical data and sterane and terpane biomarker ratios from GCMS suggest that almost all samples are in the oil window. This observation is consistent with the presence of thermogenic gas in the study area and higher vitrinite reflectance values recorded from overlying Pennsylvanian coals. These results suggest that vitrinite reflectance is a poor predictor of thermal maturity in early mature areas of Devonian shale, perhaps because reported measurements often include determinations of solid bitumen reflectance. Vitrinite reflectance interpretations in areas of early mature Devonian shale should be supplanted by evaluation of thermal maturity information from biomarker ratios and bulk geochemical data.

  13. Geologic evolution and aspects of the petroleum geology of the northern East China Sea shelf basin

    SciTech Connect

    Lee, G.H.; Kim, B.Y.; Shin, K.S.; Sunwoo, D.

    2006-02-15

    Analysis of multichannel seismic reflection profiles reveals that the northern East China Sea shelf basin experienced two phases of rifting, followed by regional subsidence. The initial rifting in the Late Cretaceous created a series of grabens and half grabens, filled by alluvial and fluviolacustrine deposits. Regional uplift and folding (Yuquan movement) in the late Eocene-early Oligocene terminated the initial rifting. Rifting resumed in the early Oligocene, while alluvial and fluviolacustrine deposition continued to prevail. A second phase of uplift in the early Miocene terminated the rifting, marking the transition to the postrift phase. The early postrift phase (early Miocene-late Miocene) is characterized by regional subsidence and westward and northwestward marine transgression. Inversion (Longjing movement) in the late Miocene interrupted the postrift subsidence, resulting in an extensive thrust-fold belt in the eastern part of the area. The entire area entered a stage of regional subsidence again and has become a broad continental shelf. Source rocks include synrift lacustrine facies, fluvial shales, and coal beds. Synrift fluvial, lacustrine, and deltaic deposits, postrift littoral and/or shallow-marine sandstones, and fractured basement have the potential to provide reservoirs. Various types of hydrocarbon traps (e.g., faulted anticlines, overthrusts, rollover anticlines, faults, unconformity traps, combination structural-stratigraphic traps, weathered basement, and stratigraphic traps) are recognized, but many of these traps have not been tested.

  14. Provenance and accommodation pathways of late Quaternary sediments in the deep-water northern Ionian Basin, southern Italy

    NASA Astrophysics Data System (ADS)

    Perri, Francesco; Critelli, Salvatore; Dominici, Rocco; Muto, Francesco; Tripodi, Vincenzo; Ceramicola, Silvia

    2012-12-01

    The northern Calabria along the southeastern coast of Italy provides a favorable setting in which to study complete transects from continental to deep-marine environments. The present northern Ionian Calabrian Basin is a wedge-top basin within the modern foreland-basin system of southern Italy. The Ionian margin of northern Calabria consists of a moderately developed fluvial systems, the Crati and Neto rivers, and diverse smaller coastal drainages draining both the Calabria continental block (i.e., Sila Massif) and the southern Apennines thrust belt (i.e., Pollino Massif). The main-channel sand of the Crati and Neto rivers is quartzofeldspathic with abundant metamorphic and plutonic lithic fragments (granodiorite, granite, gneiss, phyllite and sedimentary lithic fragments). Sedimentary lithic fragments were derived from Jurassic sedimentary successions of the Longobucco Group. The mud samples contain mostly phyllosilicates, quartz, calcite, feldspars and dolomite. Traces of gypsum are present in some samples. The I-S mixed layers, 10 Å-minerals (illite and micas), chlorite and kaolinite are the most abundant phyllosilicates, whereas smectite and chlorite/smectite mixed layers are in small amounts. The geochemical signatures of the muds reflect a provenance characterized by both felsic and mafic rocks with a significant input from carbonate rocks. Furthermore, the degree of source-area weathering was most probably of low intensity rather than moderately intense because CIA values for the studied mud samples are low. Extrapolation of the mean erosion budget from 1 to 25 Ma suggests that at least 5 to 8 km of crust have been removed from the Calabrian orogenic belt and deposited in the marine basins. The Calabrian microplate played an important role in the dynamic evolution of southern Italian fossil and modern basins, representing the key tectonic element of the entire orogenic belt.

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

    NASA Astrophysics Data System (ADS)

    Santos, Monica; Fragoso, Marcelo

    2016-04-01

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

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

    USGS Publications Warehouse

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

    2011-01-01

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

  17. Long-term geochemical connections between the Samoan hotspot and the northern Lau and North Fiji Basins

    NASA Astrophysics Data System (ADS)

    Price, A. A.; Jackson, M. G.; Blichert-Toft, J.; Hall, P. S.; Sinton, J. M.; Kurz, M. D.; Blusztajn, J.

    2013-12-01

    The Lau and North Fiji Basins provide a unique environment for the study of upper mantle flow around a subducting slab due to the juxtaposition of the Tonga Trench and the Samoan hotspot (Hart et al., 2004). Both geochemical and geophysical data suggest that material from the Samoan hotspot is leaking southward into the adjacent Lau Basin, but the direction and rate of mantle flow are difficult to constrain.Spatial variations in the isotope geochemistry of igneous rocks from the Lau Basin can provide a useful window on flow in the upper mantle. For example, some lavas from the Samoan hotspot exhibit high 3He/4He, and the observation of elevated 3He/4He at Rochambeau Bank in the nearby northern Lau Basin has been interpreted as the result of a 'finger-like' intrusion of Samoan-plume mantle into the region. However, high 3He/4He is rare even in Samoan lavas, so other geochemical signatures including radiogenic 87Sr/86Sr and Pb-isotopic compositions unique to the Samoan hotspot are useful for characterizing the spatial distribution of the Samoan component within the northern Lau and North Fiji Basins. We present analyses of a combination of geochemical tracers (He-Hf-Nd-Sr-Pb isotopes, major, and trace elements) measured on glasses from the northern Lau Basin and the North Fiji Basin. The samples have 3He/4He ratios that vary between 6 and 10.5 times atmospheric. The samples also show arange in isotopic values from extremely depleted (87Sr/86Sr=0.702892, 143Nd/144Nd=0.513218 and 176Hf/177Hf=0.283510 on a ridge 100km North of Fiji) to moderately enriched (87Sr/86Sr=0.703598, 143Nd/144Nd=0.512884 and 176Hf/177Hf=0.283082 in lavas fromPandora Ridge). Notably, moderately enriched isotopic compositions in Pandora Ridge lavas plot near Samoa's Upolu Island in isotope space, but are slightly shifted isotopically towards a depleted MORB mantle component. The new data suggestthat the western extent of the Samoan plume's influence in the region extends into both the

  18. Tectonostratigraphy of the Cenozoic Tumaco forearc basin (Colombian Pacific) and its relationship with the northern Andes orogenic build up

    NASA Astrophysics Data System (ADS)

    Borrero, Carlos; Pardo, Andrés; Jaramillo, Carlos Marcelo; Osorio, Jairo Alonso; Cardona, Agustín; Flores, Abel; Echeverri, Sebastián; Rosero, Sebastián; García, Jenny; Castillo, Hardany

    2012-11-01

    The new tectono-stratigraphic setting of the Tumaco forearc basin based on outcrop logging, cutting description from deep oil wells, new biostratigraphy on calcareous nanofossils and sandstone petrography allows a margin scale comparison of the basin response to the Caribbean and Farallón/Nazca subduction under the South American margin. The results are compared to the laterally continuous Ecuadorian Borbón forearc basin and other southern Colombian basins: Patía sub-basin, Upper Magdalena Valley and southern Putumayo-Caguán basins. The proposed basement of the Tumaco basin is a Colombian Caribbean Oceanic Plateau (CCOP) sliver docked with Santonian-Campanian island arcs that was incorporated into the Colombian Pacific forearc during the Paleocene to Eocene. The filling of the Tumaco basin started with the Oligocene Unidad 1 Sur and the Early-Middle Miocene Cayapas/Viche/Angostura/Formations in a bathyal depositional setting. At Late Miocene to Holocene, a succession of volcaniclastic units was deposited in shallower environments: the Chagüí, San Agustín and Cascajal formations, and the recent volcaniclastic fans. The Late Cretaceous evolution of Northern Andes in Colombia was influenced by the collision and fragmentation of the Colombian Caribbean Oceanic Plateau, producing in the west the Tumaco block basement and an oceanic remnant basin in Patía Valley. The convergence between the Farallón/Nazca and South American plates since Paleocene allowed the development of the Pacific forearc as well as shortening leading to the uplift of the Central Cordillera and formation of the foreland basin system, which later was divided into the Upper Magdalena Valley broken foreland basin and the southern part of the Putumayo-Caguán foreland basin. Since Miocene, events in addition to plate convergence as the collision of the Baudó-Panamá Arc and the subduction of Carnegie Ridge perturbed the subduction zone in southern Colombia. The integration of all of these

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

    NASA Astrophysics Data System (ADS)

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

    2011-10-01

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

  20. California GAMA Program: Ground-Water Quality Data in the Northern San Joaquin Basin Study Unit, 2005

    USGS Publications Warehouse

    Bennett, George L.; Belitz, Kenneth; Milby Dawson, Barbara J.

    2006-01-01

    Growing concern over the closure of public-supply wells because of ground-water contamination has led the State Water Board to establish the Ground-Water Ambient Monitoring and Assessment (GAMA) Program. With the aid of the U.S. Geological Survey (USGS) and Lawrence Livermore National Laboratory, the program goals are to enhance understanding and provide a current assessment of ground-water quality in areas where ground water is an important source of drinking water. The Northern San Joaquin Basin GAMA study unit covers an area of approximately 2,079 square miles (mi2) across four hydrologic study areas in the San Joaquin Valley. The four study areas are the California Department of Water Resources (CADWR) defined Tracy subbasin, the CADWR-defined Eastern San Joaquin subbasin, the CADWR-defined Cosumnes subbasin, and the sedimentologically distinct USGS-defined Uplands study area, which includes portions of both the Cosumnes and Eastern San Joaquin subbasins. Seventy ground-water samples were collected from 64 public-supply, irrigation, domestic, and monitoring wells within the Northern San Joaquin Basin GAMA study unit. Thirty-two of these samples were collected in the Eastern San Joaquin Basin study area, 17 in the Tracy Basin study area, 10 in the Cosumnes Basin study area, and 11 in the Uplands Basin study area. Of the 32 samples collected in the Eastern San Joaquin Basin, 6 were collected using a depth-dependent sampling pump. This pump allows for the collection of samples from discrete depths within the pumping well. Two wells were chosen for depth-dependent sampling and three samples were collected at varying depths within each well. Over 350 water-quality field parameters, chemical constituents, and microbial constituents were analyzed and are reported as concentrations and as detection frequencies, by compound classification as well as for individual constituents, for the Northern San Joaquin Basin study unit as a whole and for each individual study area

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

    NASA Astrophysics Data System (ADS)

    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

  2. Terrasar-X Insar Processing in Northern Bohemian Coal Basin Using Corner Reflectors (preliminary Results)

    NASA Astrophysics Data System (ADS)

    Hlaváčová, I.; Halounová, L.; Svobodová, K.

    2012-07-01

    The area of Northern Bohemian coal basin is rich in brown coal. Part of it is undermined, but large areas were mined using open-pit mines. There are numerous reclaimed waste dumps here, with a horse racetrack, roads and in some cases also houses. However, on most of the waste dumps, there are forests, meadows and fields. Above the coal basin, there are the Ore mountains which are suspected to be sliding down to the open mines below them. We installed 11 corner reflectors in the area and monitor them using the TerraSAR-X satellite. One of the reflectors is situated in the area of radar layover, therefore it cannot be processed. We present preliminary results of monitoring the remaining corner reflectors, with the use of 7 TerraSAR-X scenes acquired between June and December 2011. We process whole scene crops, as well as the artificial reflector information alone. Our scene set contains interferometric pairs with perpendicular baselines reaching from 0 to 150 m. Such a configuration allows us to distinguish deformations from DEM errors, which are usual when the SRTM (Shuttle Radar Topography Mission) DEM (X-band) is used for Stripmap data. Unfortunately, most of the area of interest is decorrelated due to vegetation that covers both the Ore mountains and the reclaimed waste dumps. We had to enlarge the scene crop in order to be able to distinguish deformations from the atmospheric delay. We are still not certain about the stability of some regions. For the installed artificial reflectors, the expected deformations are in the order of mm/year. Generally, deformations in the area of interest may reach up to about 5 cm/year for the Ervěnice corridor (a road and railway built on a waste dump). When processing artificial corner reflector information alone, we check triangular sums and perform the processing for all possible point combinations - and that allows us to correct for some unwrapping errors. However, the problem is highly ambiguous.

  3. Deglacial and postglacial evolution of the Pingualuit Crater Lake basin, northern Québec (Canada)

    NASA Astrophysics Data System (ADS)

    Desiage, Pierre-Arnaud; Lajeunesse, Patrick; St-Onge, Guillaume; Normandeau, Alexandre; Ledoux, Grégoire; Guyard, Hervé; Pienitz, Reinhard

    2015-11-01

    The Pingualuit Crater, located in the Ungava Peninsula (northern Québec, Canada) is a 1.4-Ma-old impact crater hosting a 245-m-deep lake. The lake has a great potential to preserve unique paleoclimatic and paleoecological sedimentary records of the last glacial/interglacial cycles in the terrestrial Canadian Arctic. In order to investigate the stratigraphy in the lake and the late Quaternary glacial history of the Pingualuit Crater, this study compiles data from three expeditions carried out in May 2007 ( 9-m-long sediment core), in August 2010 ( 50 km of seismic lines), and in September 2012 (high-resolution terrestrial LiDAR topography of the inner slopes). Despite the weak penetration ( 10 m) of the 3.5-kHz subbottom profiling caused by the presence of boulders in the sedimentary column, seismic data coupled with the stratigraphy established from the sediment core enabled the identification of two glaciolacustrine units deposited during the final stages of the Laurentide Ice Sheet (LIS) retreat in the crater. Two episodes of postglacial mass wasting events were also identified on the slopes and in the deep basin of the crater. The high-resolution topography of the internal slopes of the crater generated from the LiDAR data permitted the confirmation of a paleolake level at 545 m and determination of the elevation of drainage outlets. Together with the mapping of glacial and deglacial landforms from air photographs, the LiDAR data allowed the development of a new deglaciation and drainage scenario for the Pingualuit Crater Lake and surrounding area. The model proposes three main phases of lake drainage, based on the activation of seven outlets following the retreat of the LIS front toward the southwest. Finally, as opposed to other high-latitude crater lake basins such as Lake El'gygytgyn or Laguna Potrok Aike where high-resolution paleoclimatic records were obtained owing to high sediment accumulation rates, the seismic data from the Pingualuit Crater Lake

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

    NASA Astrophysics Data System (ADS)

    Audemard, Franck A.; Bousquet, Jean-Claude; Rodríguez, José A.

    1999-07-01

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

  5. Post-rift Magmatism at Passive Margins: An Integrated Study of the Northern Gulf of Mexico Basin

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Murphy, M. A.; Cannon, J. M.

    2014-12-01

    The pre-Cenozoic tectonic history of the Gulf of Mexico (GoM) can be broadly described as Triassic rifting, followed by Jurassic seafloor spreading and post-rift igneous activity as well as domal uplifts and rapid subsidence during the Late Cretaceous. Igneous rocks, identified from geophysical data and outcrops, extend from the Uvalde and Balcones volcanic fields in Texas, through northern Louisiana and eastern Arkansas, to the Jackson Dome in Mississippi. How this widespread magmatic event affected the thermal and structural framework of the crust and the sedimentary system in the northern GoM basin, remain poorly understood. Competing hypotheses exist regarding post-rift igneous activity: 1) Magmatism in the northeastern GoM basin is part of the Bermuda hotspot track; 2) The subduction of the Farallon plate caused distant lithospheric flexure and associated igneous activity in the northwestern GoM basin; 3) Edge-driven mantle convection produced melts at the continent-ocean boundary; 4) Grenville and Ouachita sutures led to opportunistic igneous activity. Preliminary results show that, instead of an eastward age progressive track, which is predicted by the Bermuda hotspot hypothesis, the spatial distribution and ages of igneous rocks follow the transition between continental and oceanic crust; it also roughly coincides with the Grenville and Ouachita sutures. It is also possible that the shallow-angle subduction of the Farallon plate could trigger magmatism ca. 1500 km from the trench; a modern analog is the subduction of the west Pacific plate and the Changbai volcano in northeast Asia. Here we emphasize the tectonomagmatic evolution of the northern GoM basin; and moreover suggest post-rift magmatism at passive continental margins is likely affected by both edge-driven convection and inherited lithospheric structures.

  6. Regional geohydrology of the northern Louisiana salt-dome basin; Part I, conceptual model and data needs

    USGS Publications Warehouse

    Ryals, G.N.

    1982-01-01

    As part of the National Waste Terminal Storage Program, the U.S. Geological Survey is conducting a regional study of the geohydrology of the northern Louisiana salt-dome basin and developing a regional multi-layered ground-water flow model to determine regional flow paths. In the salt-dome basin the Tokio Formation and Brownstown Marl (Austin aquifer in this report), and Nacatoch Sand of Late Cretaceous age and the Wilcox Group, Carrizo Sand, Sparta Sand, and Cockfield Formation of Tertiary age contain regional aquifers within the maximum potential repository depth of 3,000 feet. The Cretaceous units contain saltwater throughout the basin. The Tertiary units contain freshwater to varying distances downdip from outcrop areas in the basin. Natural flow directions and rates of movement of groundwater have been changed in the salt-dome basin by the withdrawl of freshwater and by the injection of wastes (principally oil-field brines) into saline aquifers. Except for the Sparta aquifer, ground-water flow directions are not well known because of a lack of potentiometric data. A regional test-drilling program, to collect the data needed to document concepts of the flow system and to quantify inputs to the planned ground-water flow model, has been proposed. The Sparta aquifer is being modeled because data are available for the unit. As regional test drilling provides data on other units, will be added to the model developed for the Sparta aquifer. (USGS)

  7. Palaeoenvironment and its control on the formation of Miocene marine source rocks in the Qiongdongnan Basin, northern South China Sea.

    PubMed

    Li, Wenhao; Zhang, Zhihuan; Wang, Weiming; Lu, Shuangfang; Li, Youchuan; Fu, Ning

    2014-01-01

    The main factors of the developmental environment of marine source rocks in continental margin basins have their specificality. This realization, in return, has led to the recognition that the developmental environment and pattern of marine source rocks, especially for the source rocks in continental margin basins, are still controversial or poorly understood. Through the analysis of the trace elements and maceral data, the developmental environment of Miocene marine source rocks in the Qiongdongnan Basin is reconstructed, and the developmental patterns of the Miocene marine source rocks are established. This paper attempts to reveal the hydrocarbon potential of the Miocene marine source rocks in different environment and speculate the quality of source rocks in bathyal region of the continental slope without exploratory well. Our results highlight the palaeoenvironment and its control on the formation of Miocene marine source rocks in the Qiongdongnan Basin of the northern South China Sea and speculate the hydrocarbon potential of the source rocks in the bathyal region. This study provides a window for better understanding the main factors influencing the marine source rocks in the continental margin basins, including productivity, preservation conditions, and the input of terrestrial organic matter.

  8. Palaeoenvironment and Its Control on the Formation of Miocene Marine Source Rocks in the Qiongdongnan Basin, Northern South China Sea

    PubMed Central

    Li, Wenhao; Zhang, Zhihuan; Wang, Weiming; Lu, Shuangfang; Li, Youchuan; Fu, Ning

    2014-01-01

    The main factors of the developmental environment of marine source rocks in continental margin basins have their specificality. This realization, in return, has led to the recognition that the developmental environment and pattern of marine source rocks, especially for the source rocks in continental margin basins, are still controversial or poorly understood. Through the analysis of the trace elements and maceral data, the developmental environment of Miocene marine source rocks in the Qiongdongnan Basin is reconstructed, and the developmental patterns of the Miocene marine source rocks are established. This paper attempts to reveal the hydrocarbon potential of the Miocene marine source rocks in different environment and speculate the quality of source rocks in bathyal region of the continental slope without exploratory well. Our results highlight the palaeoenvironment and its control on the formation of Miocene marine source rocks in the Qiongdongnan Basin of the northern South China Sea and speculate the hydrocarbon potential of the source rocks in the bathyal region. This study provides a window for better understanding the main factors influencing the marine source rocks in the continental margin basins, including productivity, preservation conditions, and the input of terrestrial organic matter. PMID:25401132

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

    NASA Astrophysics Data System (ADS)

    Meazell, K.; Flemings, P. B.

    2015-12-01

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

  10. Northern Powder River basin coal, Montana. Final environmental statement, regional analysis

    SciTech Connect

    Not Available

    1980-01-01

    This environmental statement is in two parts: a regional analysis and a site-specific analysis of coal development in the northern Powder River basin region of Montana. The regional analysis addresses cumulative impacts of coal development in the region by 1990, with emphasis on industry proposals that now require or have recently required action by Federal and state authorities. A site-specific analysis of the proposed mining and reclamation plan for the Pearl mine makes up volumes 2 and 4 of this FES. Total annual coal production from the designated region of southeastern Montana is estimated at about 39 million tons by 1980, 50 million tons by 1985, and 53 million tons by 1990. The Big Sky, Pearl, and Spring Creek mines would collectively produce approximately 15% of the total by 1980, 26.5% by 1985, and 25% by 1990. Three impacts were determined to be locally significant. The National Ambient Air Quality Standards for total suspended particulates would frequently be exceeded near all three minesites during mine life. Degradation of air quality would cause subtle injury to vegetation within about 1 mile of the mines and about 4 miles of the generating units, slightly reducing vegetative productivity. Wildlife populations, primarily antelope, mule deer, and sage grouse, would be significantly reduced during mine life and probably for several decades after mining. No threatened or endangered species would be adversely affected.Social impacts would be significant in Colstrip and Forsyth - comparable to those experienced during the construction of Colstrip units 1 and 2. At least during the 2 or 3 years of most rapid growth, local governments, formal and informal institutions, and social networks in Colstrip and Forsyth would not be able to meet the demands placed on them. Comment letters and responses are included.

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  12. Palaeoclimatic oscillations in the Pliensbachian (Lower Jurassic) of the Asturian Basin (Northern Spain)

    NASA Astrophysics Data System (ADS)

    Gómez, J. J.; Comas-Rengifo, M. J.; Goy, A.

    2015-08-01

    One of the main controversial items in palaeoclimatology is to elucidate if climate during the Jurassic was warmer than present day, with no ice caps, or if ice caps were present in some specific intervals. The Pliensbachian Cooling event (Lower Jurassic) has been pointed out as one of the main candidates to have developed ice caps on the poles. To constrain the timing of this cooling event, including the palaeoclimatic evolution before and after cooling, as well as the calculation of the seawater palaeotemperatures are of primary importance to find arguments on this subject. For this purpose, the Rodiles section of the Asturian Basin (Northern Spain), a well exposed succession of the uppermost Sinemurian, Pliensbachian and Lower Toarcian deposits, has been studied. A total of 562 beds were measured and sampled for ammonites, for biostratigraphical purposes and for belemnites, to determine the palaeoclimatic evolution through stable isotope studies. Comparison of the recorded uppermost Sinemurian, Pliensbachian and Lower Toarcian changes in seawater palaeotemperature with other European sections allows characterization of several climatic changes of probable global extent. A warming interval which partly coincides with a negative δ13Cbel excursion was recorded at the Upper Sinemurian. After a "normal" temperature interval, a new warming interval that contains a short lived positive δ13Cbel peak, was developed at the Lower-Upper Pliensbachian transition. The Upper Pliensbachian represents an outstanding cooling interval containing a positive δ13Cbel excursion interrupted by a small negative δ13Cbel peak. Finally, the Lower Toarcian represented an exceptional warming period pointed as the main responsible for the prominent Lower Toarcian mass extinction.

  13. Preserved Ross-age(?) root beneath the Transantarctic Mountains and origin of the thinner crust beneath the northern Wilkes Subglacial Basin

    NASA Astrophysics Data System (ADS)

    Jordan, Tom; Ferraccioli, Fausto; Armadillo, Egidio; Bozzo, Emanuele

    2013-04-01

    The Wilkes Subglacial Basin, in the hinterland of the Transantarctic Mountains, represents one of the least understood continental-scale features in Antarctica. Aeromagnetic data suggests that this basin was imposed on a much earlier Ross age back arc region that developed along the former active margin of the East Antarctic Craton (Ferraccioli et al., 2009, Tectonophysics). However, the deeper crustal structure of the basin and its relation with tectonic evolution remains both disputed and poorly constrained. Here, we present new airborne gravity data that reveal the crustal architecture of the northern Wilkes Subglacial Basin. Our gravity models indicate that the crust under the northern Wilkes Subglacial Basin is likely to be 30-35 km thick, i.e. 5-10 km thinner than imaged under the adjacent Transantarctic Mountains, and ~15 km thinner than predicted from some previous flexural and passive seismic models beneath the southern Wilkes Subglacial Basin region. We infer that crustal thickening under northern Victoria Land reflects Ross-age (ca 500 Ma) orogenic events and accretion, followed by partial preservation of the orogenic root since then, as opposed to reflecting the edge of a Mesozoic plateau, which has previously been inferred to have occupied West Antarctica (Bialas et al. 2007, Geology). Airy isostatic anomalies along both flanks of the Wilkes Basin reveal major inherited tectonic structures, which likely controlled the basin location and hence support aeromagnetic interpretations of the Wilkes Subglacial Basin as a structurally controlled basin. The positive anomaly along the western margin of the basin appears to define the tectonic boundary between the East Antarctic Craton and the Ross Orogen, and the anomaly along its eastern flank is interpreted as reflecting high-grade and denser rocks of the central Wilson Terran,e with respect to lower grade meta-sediments and magmatic arc rocks of the western Wilson Terrane and Wilkes Basin region. Our forward

  14. A detrital record of continent-continent collision in the Early-Middle Jurassic foreland sequence in the northern Yangtze foreland basin, South China

    NASA Astrophysics Data System (ADS)

    Qian, Tao; Liu, Shaofeng; Wang, Zongxiu; Li, Wangpeng; Chen, Xinlu

    2016-12-01

    The Mesozoic northern Yangtze foreland basin system was formed by continental collision between the North China and South China plates along the Mianlue suture. Synorogenic stratigraphic sequences of Late Triassic to Early-Middle Jurassic age were developed in the northern Yangtze foreland basin. The upper Middle Jurassic Shaximiao Formation consists mainly of thick-bedded terrestrial successions that serve as the main body of the basin-filling sequences, suggesting intense tectonism in the peripheral orogeny of the foreland basin. Laser-ICP-MS U-Pb analysis of 254 detrital zircon grains from sandstone samples and several published Lower-Middle Jurassic samples, detrital compositions, petrofacies, and paleocurrent reconstructions in the northern Yangtze foreland basin indicate that discrete source areas included the Qinling-Dabieshan ranges and the Mianlue suture zone to the north, and the South China plate to the south. The stratigraphic succession and sediment provenance of the foreland basin imply that the early Mianlue oceanic basin, magmatic arc, and nonmarine molasse foreland basin during the period of deposition were modified or buried by the subsequent continent-continent collision between the North China-Qinling-Dabieshan plate and the Yangtze plate during the Jurassic, which followed the oblique amalgamation between these plates during the Middle-Late Triassic.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

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

    USGS Publications Warehouse

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

    2016-01-01

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

  17. A new genus of aplodontid rodent (Mammalia, Rodentia) from the late Oligocene of northern Junggar Basin, China.

    PubMed

    Bi, Shundong; Meng, Jin; McLean, Sarah; Wu, Wenyu; Ni, Xijun; Ye, Jie

    2013-01-01

    A new genus and species of aplodontid rodent, Proansomys dureensis, from the late Oligocene of the northern Junggar Basin of China is described. The new genus is referred to as Ansomyinae because the ectoloph on the upper cheek teeth, although not fully crested, has attained the same characteristic bucket-handle-shaped configuration as other members of the subfamily. It represents the earliest record of the subfamily yet discovered in Asia and is more plesiomorphic than species of the genus Ansomys in having a partly crested ectoloph, a lower degree of lophodonty, and less complex tooth basins (lacking accessory lophules). Proansomys has transitional features between Prosciurus and Ansomys, suggesting that the Ansomyinae derived from a group of aplodontids related to Prosciurus, as did other advanced aplodontid rodents. This provides new light on the paleobiogeography of the Ansomyinae.

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

    SciTech Connect

    Carroll, A.R.; Graham, S.A.; Hendrix, M.S.; Ying, D.; Zhou, D.

    1995-05-01

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

  19. Quality of ground water and surface water in intermontane basins of the northern Rocky Mountains, Montana and Idaho

    USGS Publications Warehouse

    Clark, David W.; Dutton, DeAnn M.

    1996-01-01

    The Regional Aquifer-System Analysis (RASA) program is a series of studies by the U.S. Geological Survey (USGS) to analyze regional ground-water systems that compose a major portion of the Nations water supply (Sun, 1986). The Northern Rocky Mountains Intermontane Basins is one of the study regions in this national program. The main objectives of the RASA studies are to: (1) describe the ground-water systems as they exist today, (2) analyze the known changes that have led to the system's present condition, (3) combine results of previous studies in a regional analysis, where possible, and (4) provide means by which effects of future ground-water development can be estimated.The purpose of this study, which began in 1990, was to increase understanding of the hydrogeology of the intermontane basins of the Northern Rocky Mountains area. This report is Chapter C of a three-part series and describes the quality of ground water and surface water in the study area. Chapter A (Tuck and others, 1996) describes the geologic history and generalized hydrogeologic units. Chapter B (Briar and others, 1996) describes the general distribution of ground-water levels in basin-fill deposits.Water-quality data illustrated in this report represent the distribution of concentrations and composition of dissolved solids in ground water and surface water in the intermontane areas. The chemistry of ground and surface water in the intermontane areas is influenced by the chemical and physical nature of the rocks in the basin deposits of the valleys and surrounding bedrock in the mountains.

  20. An astronomically calibrated early Paleocene magnetostratigraphy and biostratigraphy at Zumaia (Basque Basin, Northern Spain)

    NASA Astrophysics Data System (ADS)

    Dinarès-Turell, J.; Baceta, J. I.; Pujalte, V.; Orue-Etxebarria, X.; Bernaola, G.; Lorito, S.

    2003-04-01

    We have retrieved the magnetostratigraphy of a 54 m long section above the Cretaceous-Tertiary boundary at the sea-cliff section of Zumaia in the Basque basin (Northern Spain). The section encompasses the entire Danian and the lower part of the Selandian stages as indicated by calcareous plankton biostratigraphy (planktic foraminifera and calcareous nannofossils) performed along section. The studied interval is made up by pelagic-marl alternations in the form of couplets and bundles, which range from centimetre/decimetre to meter scale respectively including a few intercalations of thin-bedded calcareous turbidites. The pelagic carbonate beds grade from reddish-pink to light grey colour and are similar to many well-known pelagic sequences like the Scaglia Rossa sequences in the Umbrian basin from Italy, which have provided reference Paleocene magneto- and biostratigraphic chronologies. Our magnetostratigraphy is based in the identification of the primary remanence component after stepwise thermal demagnetisation up to 580-600°C in samples from about 200 stratigraphic levels, which allows the identification of six reversal boundaries from chron C29r to C26r at a bed level. A lithologically coded series has been derived for the studied section taking also the colour information into account and studied with spectral analysis. The spatial (or temporal) evolution of periodicities in the coded series is studied with a wavelet spectral technique. The same wavelet approach has been performed on a published calcium carbonate record for the lower Paleocene 14 m of the Zumaia section (Ten Kate and Sprenger, 1993) obtaining comparable results, which validates our lithologically coded approach. A preliminary time-model based on the standard GPTS indicates that the basic lithologic carbonate-marl couplet corresponds to the 19-23 ky precession cycle (21-31 cm cycle in the depth domain) and that a cycle (usually bundles of 4-6 basic couplets) with global periodicity centred at 1

  1. Seismic waves attenuation in the lithosphere of the northern Basin and Range Province

    NASA Astrophysics Data System (ADS)

    Dobrynina, Anna

    2013-04-01

    The seismic quality factor of the direct body waves (P- and S-waves) and coda and their frequency dependence (n) were estimated for the northern Basin and Range Province using traces of 66 local earthquakes and explosions recorded during 1988-1989 PASSCAL Basin and Range Passive Seismic Experiment. For calculation of Q-coda the single backscattering model by Aki was used. Q-coda values were estimated for six central frequencies (f): 0.3±0.1, 0.75±0.25, 1.5±0.5, 3.0±1.0, 6.0±2.0 and 12.0±4.0 Hz and for 18 lapse time windows (W) - from 10 to 95 sec with a step 5 sec. The Qp and Qs values were obtained by the method of the maximum amplitudes for the frequency bands 0.5-1.0, 1.0-2.0, 2.0-4.0 ? 4.0-8.0 Hz. Also we tired to evaluate the part of the intrinsic and scattering attenuation (Qi and Qsc respectively) in the total attenuation using Wennerberg's method. The Q-coda increases and the frequency parameter n and the attenuation coefficient δ decrease with increasing of frequency and lapse time windows. This fact shows that the upper part of the lithosphere is more heterogeneous compared to its lower layers. The deep variations of the frequency parameter n and the attenuation coefficient δ show the sharp change at the depth about 150 km - at the same depth the boundary of the low velocity anomaly is observed (Bensen et al., 2009; Wagner et al., 2012; Shen et al., 2012). The Qs and Qp values also increase with frequency: Qs varies from 42 (0.84 Hz) to 298 (5.52 Hz) and Qp - from 60 (0.84 Hz) to 279 (6.05 Hz). The following empirical relations of Q vs. f are deduced for P- and S-waves respectively: Qp(f)=69*f0.78 and Qs(f)=53*f1.08. The Q-values, describing the intrinsic and scattering attenuation, also show a significant dependence on frequency and lapse time windows: the empirical relations of Q vs. f are: Qi(f)=8*f1.2 and Qsc(f)=13*f1.1 (for W=10 sec) and Qi(f)=5*f1.2 and Qsc(f)=102*f1.0 (for W=95 sec) respectively. The comparison of the intrinsic and

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

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

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

  3. Biomarkers of contaminant exposure in Northern Pike (Esox lucius) from the Yukon River Basin, Alaska.

    PubMed

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

    2007-05-01

    As part of a larger investigation, northern pike (n = 158; Esox lucius) were collected from ten sites in the Yukon River Basin (YRB), Alaska, to document biomarkers and their correlations with organochlorine pesticide (total p,p'-DDT, total chlordane, dieldrin, and toxaphene), total polychlorinated biphenyls (PCBs), and elemental contaminant (arsenic, cadmium, copper, lead, total mercury, selenium, and zinc) concentrations. A suite of biomarkers including somatic indices, hepatic 7-ethoxyresorufin O-deethylase (EROD) activity, vitellogenin concentrations, steroid hormone (17B- ustradiol and 16-kebtestosteront) concentrations, splenic macrophage aggregates (MAs), oocyte atresia, and other microscopic anomalies in various tissues were documented in YRB pike. Mean condition factor (0.50 to 0.68), hepatosomatic index (1.00% to 3.56%), and splenosomatic index (0.09% to 0.18%) were not anomalous at any site nor correlated with any contaminant concentration. Mean EROD activity (0.71 to 17.51 pmol/min/mg protein) was similar to basal activity levels previously measured in pike and was positively correlated with selenium concentrations (r = 0.88, P < 0.01). Vitellogenin concentrations in female (0.09 to 5.32 mg/mL) and male (<0.0005 to 0.097 mg/mL) pike were not correlated with any contaminant, but vitellogenin concentrations >0.01 mg/mL in male pike from multiple sites indicated exposure to estrogenic compounds. Mean steroid hormone concentrations and percent oocyte atresia were not anomalous in pike from any YRB site. Few site differences were significant for mean MA density (1.86 to 6.42 MA/mm(2)), size (812 to 1481 microm(2)), and tissue occupied (MA-%; 0.24% to 0.75%). A linear regression between MA-% and total PCBs was significant, although PCB concentrations were generally low in YRB pike (< or =63 ng/g), and MA-% values in female pike (0.24% to 0.54%) were lower than in male pike (0.32% to 0.75%) at similar PCB concentrations. Greater numbers of MAs were found as

  4. Aerosol chemistry above an extended archipelago of the eastern Mediterranean basin during strong northern winds

    NASA Astrophysics Data System (ADS)

    Athanasopoulou, E.; Protonotariou, A. P.; Bossioli, E.; Dandou, A.; Tombrou, M.; Allan, J. D.; Coe, H.; Mihalopoulos, N.; Kalogiros, J.; Bacak, A.; Sciare, J.; Biskos, G.

    2015-07-01

    Detailed aerosol chemical predictions by a comprehensive model system (i.e. PMCAMx, WRF, GEOS-CHEM), along with airborne and ground-based observations, are presented and analysed over a wide domain covering the Aegean Archipelago. The studied period is 10 successive days in 2011, characterized by strong northern winds, which is the most frequently prevailing synoptic pattern during summer. The submicron aerosol load in the lower troposphere above the archipelago is homogenously enriched in sulfate (average modelled and measured submicron sulfate of 5.5 and 5.8 μg m-3, respectively), followed by organics (2.3 and 4.4 μg m-3) and ammonium (1.5 and 1.7 μg m-3). Aerosol concentrations smoothly decline aloft, reaching lower values (< 1 μg m-3) above 4.2 km altitude. The evaluation criteria rate the model results for sulfate, ammonium, chloride, elemental carbon, organic carbon and total PM10 mass concentrations as "good", indicating a satisfactory representation of the aerosol chemistry and precursors. Higher model discrepancies are confined to the highest (e.g. peak sulfate values) and lowest ends (e.g. nitrate) of the airborne aerosol mass size distribution, as well as in airborne organic aerosol concentrations (model underestimation ca. 50 %). The latter is most likely related to the intense fire activity at the eastern Balkan area and the Black Sea coastline, which is not represented in the current model application. The investigation of the effect of local variables on model performance revealed that the best agreement between predictions and observations occurs during high winds from the northeast, as well as for the area confined above the archipelago and up to 2.2 km altitude. The atmospheric ageing of biogenic particles is suggested to be activated in the aerosol chemistry module, when treating organics in a sufficient nitrogen and sulfate-rich environment, such as that over the Aegean basin. More than 70 % of the predicted aerosol mass over the Aegean

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

    USGS Publications Warehouse

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

    2007-01-01

    As part of a larger investigation, northern pike (n = 158; Esox lucius) were collected from ten sites in the Yukon River Basin (YRB), Alaska, to document biomarkers and their correlations with organochlorine pesticide (total p,p'-DDT, total chlordane, dieldrin, and toxaphene), total polychlorinated biphenyls (PCBs), and elemental contaminant (arsenic, cadmium, copper, lead, total mercury, selenium, and zinc) concentrations. A suite of biomarkers including somatic indices, hepatic 7-ethoxyresorufin O-deethylase (EROD) activity, vitellogenin concentrations, steroid hormone (17B- ustradiol and 16-kebtestosteront) concentrations, splenic macrophage aggregates (MAs), oocyte atresia, and other microscopic anomalies in various tissues were documented in YRB pike. Mean condition factor (0.50 to 0.68), hepatosomatic index (1.00% to 3.56%), and splenosomatic index (0.09% to 0.18%) were not anomalous at any site nor correlated with any contaminant concentration. Mean EROD activity (0.71 to 17.51 pmol/min/mg protein) was similar to basal activity levels previously measured in pike and was positively correlated with selenium concentrations (r = 0.88, P < 0.01). Vitellogenin concentrations in female (0.09 to 5.32 mg/mL) and male (0.01 mg/mL in male pike from multiple sites indicated exposure to estrogenic compounds. Mean steroid hormone concentrations and percent oocyte atresia were not anomalous in pike from any YRB site. Few site differences were significant for mean MA density (1.86 to 6.42 MA/mm2), size (812 to 1481 ??m2), and tissue occupied (MA-%; 0.24% to 0.75%). A linear regression between MA-% and total PCBs was significant, although PCB concentrations were generally low in YRB pike (???63 ng/g), and MA-% values in female pike (0.24% to 0.54%) were lower than in male pike (0.32% to 0.75%) at similar PCB concentrations. Greater numbers of MAs were found as zinc concentrations increased in YRB female pike, but it is unlikely that this is a causative relationship

  6. Trace Perchlorate in Background Ground Water and Local Precipitation, Northern Rio Grande Basin, New Mexico

    NASA Astrophysics Data System (ADS)

    Dale, M.; Longmire, P.; Granzow, K. P.; Englert, D.; Yanicak, S.; Larson, T.; Rearick, M.; Heikoop, J.; Perkins, G.

    2007-12-01

    Perchlorate occurs at detectable concentrations of 0.07 to 0.45 parts per billion (ppb) in ground water of background quality within the northern Rio Grande basin, New Mexico. Ground-water samples were collected from 47 wells and springs near Los Alamos, Santa Fe, and Taos, New Mexico. Analytical methods consisted of liquid and ion chromatography-mass spectrometry mass spectrometry (LC/MS/MS and IC/MS/MS). An upper tolerance limit (mean plus two standard deviations) of 0.40 ppb was calculated from 184 analytical results for the background samples. Six distinguishable ground-water zones were sampled based on location, age, and hydrochemistry. In the Los Alamos area, ground water within the mountain-front and mountain-block region is mostly young or modern (less than 50 years). The regional aquifer including the White Rock Canyon springs are of sub-modern age (greater than 50 years). Tritium data from springs north of Taos indicate ground water of modern and sub-modern ages. Background perchlorate concentrations within the Los Alamos area were consistently higher than those measured in the Taos area. Ground water from the Taos area contains less perchlorate and has lower δ18O and δ2H values than ground water from the Los Alamos area. The elevation at which precipitation occurs with respect to recharge and/or the amount of evapotranspiration may play a role in perchlorate concentration in ground water. Natural variability, hydrogeology, and atmospheric inputs may also affect perchlorate concentration in ground water. A linear regression through perchlorate and chloride concentrations for all stations resulted in an r2 = 0. However, the r2 value of the Los Alamos regional aquifer for perchlorate versus chloride was 0.66. Thirteen precipitation samples were collected in the Los Alamos area. Results from eleven of these samples showed no perchlorate greater than 0.05 and 0.009 ppb, the method detection limit (MDL). Two precipitation samples analyzed using the IC

  7. Radar Probing of Planetary Regoliths: An Example from the Northern Rim of Imbrium Basin

    NASA Technical Reports Server (NTRS)

    Thompson, Thomas W.; Campbell, Bruce A.; Ghent, Rebecca R.; Hawke, B. Ray; Leverington, David W.

    2006-01-01

    Imaging radar measurements at long wavelengths (e.g., >30 cm) allow deep (up to tens of meters) probing of the physical structure and dielectric properties of planetary regoliths. We illustrate a potential application for a Mars orbital synthetic aperture radar (SAR) using new Earth-based 70-cm wavelength radar data for the Moon. The terrae on the northern margin of Mare Imbrium, the Montes Jura region, have diffuse radar backscatter echoes that are 2-4 times weaker at 3.8-cm, 70-cm, and 7.5-m wavelengths than most other lunar nearside terrae. Possible geologic explanations are (1) a pyroclastic deposit associated with sinuous rilles in this region, (2) buried mare basalt or a zone of mixed highland/basaltic debris (cryptomaria), or (3) layers of ejecta associated with the Iridum and Plato impacts that have fewer meter-sized rocks than typical highlands regolith. While radar data at 3.8-cm to 7.5-m wavelengths suggest significant differences between the Montes Jura region and typical highlands, the surface geochemistry and rock abundance inferred from Clementine UV-VIS data and eclipse thermal images are consistent with other lunar terrae. There is no evidence for enhanced iron abundance, expected for basaltic pyroclastic deposits, near the source vents of the sinuous rilles radial to Plato. The regions of low 70-cm radar return are consistent with overlapping concentric ''haloes'' about Iridum and Plato and do not occur referentially in topographically low areas, as is observed for radar-mapped cryptomaria. Thus we suggest that the extensive radar-dark area associated with the Montes Jura region is due to overlapping, rock-poor ejecta deposits from Iridum and Plato craters. Comparison of the radial extent of low-radar-return crater haloes with a model for ejecta thickness shows that these rock-poor layers are detected by 70-cm radar where they are on the order of 10 m and thicker. A SAR in orbit about Mars could use similar deep probing to reveal the nature of

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

    NASA Astrophysics Data System (ADS)

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

    2007-05-01

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

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

    USGS Publications Warehouse

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

    1990-01-01

    The geochemistry and stable isotopes of groundwaters, surface waters, and precipitation indicate different sources of some dissolved constituents, but a common source of recharge and other constituents in two adjacent closed basins in the Atacama Desert region of northern Chile (24??15???-24??45???S). Waters from artesian wells, trenches, and ephemeral streams in the Punta Negra Basin are characterized by concentrations of Na>Ca>Mg and Cl ???SO4, with TDS Mg ??? Ca and SO4 > Cl, with TDS also Mg ??? Ca and SO4 > Cl, but with TDS up to 40 g/l. The deep mine waters have pH between 3.2 and 3.9, and are high in dissolved CO2 (??13 C = -4.8%PDB), indicating probable interaction with oxidizing sulfides. The deep mine waters have ??18O values of ???-1.8%.compared with values < -3.5??? for other Hamburgo Basin waters; thus the mine waters may represent a mixture of meteoric waters with deeper "metamorphic" waters, which had interacted with rocks and exchanged oxygen isotopes at elevated temperatures. Alternatively, the deep mine waters may represent fossil meteoric waters which evolved isotopically along an evaporative trend starting from values quite depleted in ??18O and ??Dd relative to either precipitation or shallow groundwaters. High I/Br ratios in the Hamburgo Basin waters and La Escondida mine waters are consistent with regionally high I in surficial deposits in the Atacama Desert region and may represent dissolution of a wind-blown evaporite component. Rain and snow collected during June 1984, indicate systematic ??18O and ??D fractionation with increasing elevation between 3150 and 4180 m a.s.l. (-0.21??.??18O and -1.7??.??D per 100 m). Excluding the deep mine waters from La Escondida, the waters from the Hamburgo and Punta Negra Basins have similar ??D and ??18O values and together show a distinct evaporative trend (??D = 5.0 ??18O - 20.2). Snowmelt from the central Andes Cordillera to the east is the most likely source of recharge to both basins. Some of the

  10. Geomorphic and hydroclimatic controls on the formation of evaporite deposits in the Qaidam Basin, northern Tibetan Plateau, China*

    NASA Astrophysics Data System (ADS)

    Yu, J.; Zhang, L.; Gao, C.; Cheng, A.; He, X.

    2012-12-01

    Qaidam Basin is a hyperarid inland basin with an area of 121×103 km2 located on the northern Tibetan Plateau. One fourth of the basin today is covered by playas and hypersaline lakes. About 80% of brine lithium found in China is contained mostly in four salt lakes: Bieletan (BLT), DongTaijinaier (DT), XiTaijinaier (XT) and Yiliping (YLP). The Li+-rich interstitial brines are associated with the halite-dominated evaporite strata or evaporitic sediments, coexisting with K+-rich brines. Our recent investigation found that the contrasting hydroclimatic conditions between the high mountains containing ice caps and the terminal basins with salt lakes are central to the evaporite deposition. The greater than 4000 m of relief in the watershed enables a massive amount of ions to be weathered and transported together with clastic material from the huge, relatively wet alpine regions to the hyperarid terminal basins, where intense evaporation rapidly enriches the lake water, resulting in the formation of the evaporitic sequences and associated brine deposits. The topographically-induced differential effects of the middle-latitude westerlies are probably raised in a warmer climate, bringing about conditions more favourable for evaporite deposition than today. This is because precipitation increases in the mountainous catchment as a result of enhanced condensation triggered by increased vertical inflows when the alpine surface is warmer, whereas evaporation enhances in the Qaidam Basin under higher summer temperature and rain shadow effect. Qarhan Playa, the largest salt lake in the Qaidam Basin, for example, should have larger inundated areas than today during the early-middle Holocene when the summer was warmer, thus increased evaporite mineral production. Another finding of our work is the geomorphic control associated with the evolution of two large alluvial fans on the depositional system of the four salt lakes. Data from lithostratigraphic correlation of representative

  11. Invasions and impacts of alligatorweed in the upper Xiaoqing River basin of northern China

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Alligatorweed (Alternanthera philoxeroides (Mart.) Griseb), is a problematic and difficult to manage invasive weed. The recent invasion in the upper Xiaoqing River, northern China extends its range northwards through almost five degrees latitude and 500 km from the northern limit and main invasion a...

  12. Seismotectonic analysis of the Lunigiana and Garfagnana extensional basins (Northern Tuscany, Italy)

    NASA Astrophysics Data System (ADS)

    Brozzetti, F.; Boncio, P.; di Naccio, D.; Lavecchia, G.; Torelli, L.; Eva, E.; Solarino, S.

    2009-04-01

    We investigated the active and potentially seismogenic sources of the Lunigiana and Garfagnana extensional basins by integrating geological and morpho-structural surveys with seismological and seismic reflection data. The Lunigiana and Garfagnana basins are NW-SE grabens, originated in the hanging wall of a E-NE dipping low-angle detachment faults outcropping in the northern Tuscany Apennines. The conjugate faults bounding the basins join with the detachment at depths varying from 1 to 2.5 sec TWT, from W to E. The outcrop expression of the two fault sets is similar but the east-dipping faults show, on average, lower dip-angles (i) (30°4 km) than the west-dipping ones (50°

  13. Petroleum systems of the Po Basin Province of northern Italy and the northern Adriatic Sea; Porto Garibaldi (biogenic), Meride/Riva di Solto (thermal), and Marnoso Arenacea (thermal)

    USGS Publications Warehouse

    Lindquist, Sandra J.

    1999-01-01

    The Porto Garibaldi total petroleum system dominates the Po Basin Province of onshore northern Italy and offshore Italy and Croatia in the northern Adriatic Sea. Porto Garibaldi contains Pliocene (primarily) and Pleistocene (secondarily) biogenic gas ? approximately 16 TCF (2.66 BBOE) ultimately recoverable ? accumulated in co-eval siliciclastic reservoirs. This area was the northwestern edge of the Gondwanan (African) continental plate in pre-Hercynian time until the assembly of Pangea, a dominantly carbonate passive continental margin during the Mesozoic breakup of Pangea, and a Cenozoic collision zone with siliciclastic foredeep and foreland regions surrounded by thrust belts. At least two other petroleum systems, with Triassic (Meride / Riva di Solto) and Miocene (Marnoso Arenacea) source rocks, contribute oil and thermal gas reserves (nearly 1 BBOE) to the province. The major time of hydrocarbon expulsion of the thermal systems was Late Neogene during the Alpine and Apennine orogenies. Local Mesozoic oil expulsion from Triassic rocks also occurred, but those oils either were not trapped or were leaked from faulty traps through time.

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

    USGS Publications Warehouse

    Kendy, Eloise; Tresch, R.E.

    1996-01-01

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

  15. A modern analogue for tectonic, eustatic, and climatic processes in cratonic basins: Gulf of Carpentaria, northern Australia

    USGS Publications Warehouse

    Edgar, N. Terence; Cecil, C. Blaine; Mattick, R.E.; de Deckker, Patrick; Djajadihardja, Yusuf S.

    2003-01-01

    The Gulf of Carpentaria is a tropical, silled epicontinental sea and may be a modern analogue for ancient cratonic basins. For the purpose of this study, the Gulf of Carpentaria is compared to Pennsylvanian cratonic basins of the United States. During the Pennsylvanian, the North American continent moved from the Southern Hemisphere, through the Equator, into the Northern Hemisphere. Today, the Gulf of Carpentaria–New Guinea region is a few degrees south of the Equator and is moving towards it. During the Pennsylvanian, the world was subjected to major glaciations and associated sea-level changes. The island of New Guinea and the Gulf of Carpentaria have undergone similar processes during the Quaternary. A reconnaissance seismic survey of the gulf conducted by the USGS and the Australian National University (ANU), combined with oil-exploration well data, provided the first step in a systematic evaluation of a modern tropical epicontinental system. During the Cenozoic, the region was dominated by terrestrial sedimentation in a temperate climate. At the same time, carbonates were being deposited on the northern shelf edge of the Australian Plate. During the Miocene, carbonate deposition expanded southward into the gulf region. Then in the Late Miocene, carbonate sedimentation was replaced by terrigenous clastics derived from the developing Central Range of the island of New Guinea, which developed a wetter climate while moving northwards into the tropics. At least 14 basin-wide transgressive–regressive cycles are identified by channels that were eroded under subaerial conditions since about the Miocene. Comparison of the modern Gulf of Carpentaria sequences with those of the Pennsylvanian reveals many similarities.

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

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

  17. Provenance evolution of the Jurassic northern Qaidam Basin (West China) and its geological implications: evidence from detrital zircon geochronology

    NASA Astrophysics Data System (ADS)

    Yu, Long; Xiao, Ancheng; Wu, Lei; Tian, Yuntao; Rittner, Martin; Lou, Qianqian; Pan, Xiaotian

    2017-03-01

    The Jurassic system is the major hydrocarbon source rock and of crucial importance for understanding the Mesozoic intra-continental tectonics in West China. This paper presents systematic detrital zircon geochronology of the Jurassic outcropping at the Dameigou locality in the northern Qaidam Basin, and reports 1000 single-grain U-Pb zircon ages that have implications for the provenance, the corresponding basin property as well as the tectonic setting of West China during Jurassic. Zircon ages exhibit two major clusters at 250 and 2400 Ma whereas two minor clusters at 450 and 850 Ma, suggesting primary sources from the East Kunlun Shan and Oulongbuluke Block, secondary sources from the North Qaidam UHP belt and South Qilian Shan. Combined with observation of lithology and sedimentary facies, two rifting periods were inferred in the earliest Jurassic and the early stage of the Middle Jurassic, respectively, accompanied by further extension throughout the Jurassic. Our results do not support a foreland basin related to the Jurassic southward thrusting of the South Qilian Shan, but favor that the Mesozoic intra-continental tectonics in West China were characterised by pulsed responses to specific collisions rather than a persisting contractional setting during Jurassic period.

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

    NASA Astrophysics Data System (ADS)

    Kikuchi, C. P.; Ferré, T. P. A.

    2016-09-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

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

  20. Ecological characterization of the central and northern California coastal region. Volume IV. Watersheds and basins. Chapters 1-16

    SciTech Connect

    Not Available

    1981-10-01

    Central and northern coastal California is such a large and diverse region that it is subdivided into smaller units for ease in presenting site-specific information. A separate chapter was prepared for each of 22 watersheds and five offshore basins, and each contains site-specific information. Chapters on the watersheds contain information on terrestrial, freshwater, and estuarine physical-chemical processes and features, biological resources, and socio-economic activities. Chapters about the basins contain information on intertidal, pelagic and subtidal benthic physical-chdmical processes and features, biological resources, and socio-economic activities. Watershed chapters contain descriptions of geology, soils, climate, tsunami hazard, hydrology, water quality, and other topics. The biological resources section of each watershed description contains information on selected species and areas of ecological concern. Preserves, reserves, refuges, conservation areas, sites of known scientific and educational value, anadromous fish spawning areas, wild and scenic rivers, important nesting sites, and waterfowl and shorebird concentrating locations are described and mapped as areas of ecological concern. Socio-economic descriptions include land use, economics, population, environmental issues and other topics, both existing data and trends. The basin chapters contain similar kinds of information but with a greater emphasis on substrate distribution maps.

  1. Ecological characterization of the central and northern Califorina coastal region. Volume IV. Watersheds and basins. Chapters 17-29

    SciTech Connect

    Not Available

    1981-10-01

    Central and northern coastal California is such a large and diverse region that it is subdivided into smaller units for ease in presenting site-specific information. A separate chapter was prepared for each of 22 watersheds and five offshore basins, and each contains site-specific information. Chapters on the watersheds contain information on terrestrial, freshwater, and estuarine physical-chemical processes and features, biological resources, and socio-economic activities. Chapters about the basins contain information on intertidal, pelagic and subtidal benthic physical-chemical processes and features, biological resources, and socio-economic activities. Watershed chapters contain descriptions of geology, soils, climate, tsuanami hazard, hydrology, water quality, and other topics. The biological resources section of each watershed description contains information on selected species and areas of ecological concern. Preserves, reserves, refuges, conservation areas, sites of known scientific and educational value, anadromous fish spawning areas, wild and scenic rivers, important nesting sites, and waterfowl and shorebird concentrating locations are described and mapped as areas of ecological concern. Socio-economic descriptions include land use, economics, population, environmental issues and other topics, both existing data and trends. The basin chapters contain similar kinds of information but with a greater emphasis on substrate distribution maps.

  2. Genetic structure of lake whitefish, Coregonus clupeaformis, populations in the northern main basin of Lake Huron

    USGS Publications Warehouse

    Stott, Wendylee; Ebener, Mark P.; Mohr, Lloyd; Schaeffer, Jeff; Roseman, Edward F.; Harford, William J.; Johnson, James E.; Fietsch, Cherie-Lee

    2012-01-01

    Genetic analysis of spawning lake whitefish (Coregonus clupeaformis) from six sites in the main basin of Lake Huron was conducted to determine population structure. Samples from fisheryindependent assessment surveys in the northwest main basin were analyzed to determine the relative contributions of lake whitefish genetic populations. Genetic population structure was identified using data from seven microsatellite DNA loci. One population was identified at Manitoulin Island, one to two were observed in the east-central main basin (Fishing Island and Douglas Point), and one to two populations were found in the northwest (Thunder Bay and Duncan Bay). The genetic identity of collections from Duncan Bay and Thunder Bay was not consistent among methods used to analyze population structure. Low genetic distances suggested that they comprised one population, but genic differences indicated that they may constitute separate populations. Simulated data indicated that the genetic origins of samples from a mixed-fishery could be accurately identified, but accuracy could be improved by incorporating additional microsatellite loci. Mixture analysis and individual assignment tests performed on mixed-stock samples collected from the western main basin suggested that genetic populations from the east-central main basin contributed less than those from the western main basin and that the proportional contribution of each baseline population was similar in each assessment sample. Analysis of additional microsatellite DNA loci may be useful to help improve the precision of the estimates, thus increasing our ability to manage and protect this valuable resource.

  3. Tectonic history of northern New Caledonia Basin from deep offshore seismic reflection: Relation to late Eocene obduction in New Caledonia, southwest Pacific

    NASA Astrophysics Data System (ADS)

    Collot, Julien; Geli, Louis; Lafoy, Yves; Vially, Roland; Cluzel, Dominique; Klingelhoefer, Frauke; Nouzé, Hervé

    2008-12-01

    New, high-quality multichannel seismic reflection data from the western New Caledonia offshore domain allow for the first time the direct, continuous connection of seismic reflectors between the Deep Sea Drilling Project 208 drill hole on the Lord Howe Rise and the New Caledonia Basin. A novel seismic interpretation is hence proposed for the northern New Caledonia Basin stratigraphy, which places the Eocene/Oligocene unconformity deeper than previously thought and revisits the actual thickness of the pre-Oligocene sequences. A causal link is proposed between the obduction of the South Loyalty Basin over New Caledonia (NC) and the tectonic history of the northern New Caledonia Basin. Here it is suggested that as the South Loyalty Basin was being obducted during early Oligocene times, the NC Basin subsided under the effect of the overloading and underthrusted to accommodate the compressional deformation, which resulted in (1) the uplift of the northern Fairway Ridge and (2) the sinking of the western flank of New Caledonia. This event also had repercussions farther west with the incipient subsidence of the Lord Howe Rise.

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  5. Deep structure of the northern Rio Grande rift beneath the San Luis basin (Colorado) from a seismic reflection survey: implications for rift evolution

    NASA Astrophysics Data System (ADS)

    Tandon, Kush; Brown, Larry; Hearn, Thomas

    1999-02-01

    A seismic reflection survey by Chevron across the San Luis basin (northern Rio Grande rift) and San Juan volcanic field of southern Colorado is reprocessed with extended correlation to search for basement structure. The trace of the main bounding fault of the basin, a high-angle normal fault against the Sangre de Cristo Range, can be correlated to a wide zone of dipping reflection fabric and soles out at lower crustal depths (26-28 km). The deeper reflection fabric represent either broad extensional strain or pre-existing structure, such as a Laramide thrust system. The Sangre de Cristo bounding fault in San Luis basin does not sole out at mid-crustal depths but continues into the lower crust with a shallower dip. The basin architecture in the northern Rio Grande rift (San Luis basin) provides little if any evidence that the Sangre de Cristo bounding fault should flatten in a shallow listric fashion. This fault geometry is quite similar to the high-angle bounding fault in the Espanola basin but contrasts with less deeply-rooted faults in the Albuquerque basin in the central Rio Grande rift. Deeper soling out of the Sangre de Cristo bounding fault could be due to less extension in the northern Rio Grande rift and/or greater strength of the lithosphere compared to the central Rio Grande rift. Unequivocal Moho reflections beneath the San Luis basin cannot be identified, probably due to limited signal penetration or a gradational nature of the Moho. The majority of rift-related movement observed on the Sangre de Cristo bounding fault is post-Eocene. Either the western margin of the basin is marked by a tight monocline or a low-angle normal fault.

  6. Sedimentologic and paleoclimatic reconstructions of carbonate factory evolution in the Alborz Basin (northern Iran) indicate a global response to Early Carboniferous (Tournaisian) glaciations

    NASA Astrophysics Data System (ADS)

    Sardar Abadi, Mehrdad; Kulagina, Elena I.; Voeten, Dennis F. A. E.; Boulvain, Frédéric; Da Silva, Anne-Christine

    2017-03-01

    The Lower Carboniferous Mobarak Formation records the development of a storm-sensitive pervasive carbonate factory on the southern Paleo-Tethyan passive margin following the opening of the Paleo-Tethys Ocean into the Alborz Basin along the northern margin of Gondwana. Its depositional facies encompass inner ramp peritidal environments, peloidal to crinoidal shoals, storm to fair-weather influenced mid-ramps, proximal to distal shell beds and low energy outer ramps. Sedimentological analyses and foraminiferal biostratigraphy reveal four events affecting carbonate platform evolution in the Alborz Basin during the Lower Carboniferous: (1) A transgression following global temperature rise in the Early Tournaisian (middle Hastarian) caused the formation of thick-bedded argillaceous limestones. This interval correlates with Early Tournaisian nodular to argillaceous limestones in the Moravia Basin (Lisen Formation, Czech Republic), the Dinant Basin (Pont d'Arcole Formation, Belgium), and at the Rhenish Slate Mountains (Lower Alum shale, Germany). (2) Late Hastarian-early Ivorian glaciations previously identified in Southern Gondwana but had not yet recognized in Northern Gondwana were recorded through a sequence boundary. (3) During the Late Tournaisian-Early Visean?, a differential block faulting regime along the basin's margin caused uplift of the westernmost parts of the Alborz Basin and resulted in subsidence in the eastern part of the central basin. This tectonically controlled shift in depositional regime caused vast sub-aerial exposure and brecciation preserved in the top of the Mobarak Formation in the western portion of the Central Alborz Basin. (4) Tectonic activity coinciding with a progressive, multiphase sea level drop caused indirectly by the Viséan and Serpukhovian glaciations phases ultimately led to the stagnation of the carbonate factory. Paleothermometry proxies, the presence of foraminiferal taxa with a northern Paleo-Tethyan affinity and evidence for

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    The Santo Domingo Basin, one of a series of basins within the Rio Grande Rift, is located between Santa Fe and Albuquerque, NM, and has been the focus of research by the Summer of Geophysical Experience (SAGE) program since 2000. Gravity, magnetotelluric (MT), and seismic data have been collected throughout the region, although we are concentrating on gravity and MT data collected during SAGE 2014 and 2015. The study area is located in the center of the Santo Domingo basin, an extensional, Miocene age, rift basin, in an area that was minimally involved in the preceding local Laramide orogenic activity. Rift sediments (~3.5 km thick) are underlain by Eocene age sediments that were shed from adjacent uplifts. Up to 3 km of Mesozoic and Paleozoic sediments are preserved above the Precambrian basement. Geologic outcrop, borehole and seismic reflection data, and known density values were used in the construction of a ~100 km-long, generalized geologic cross section from which a gravity response was calculated. The modeled gravity response makes fairly definitive predictions about the geometry of the basin as well as the stratigraphy and faulting within and bounding the basin. MT data was collected at ten stations within the basin. The MT sounding curves exhibit one-dimensional behavior at short periods (<10 s), not surprisingly considering the relatively flat local structure in the area. Layered-earth MT models, without geologic constraints, show a conductive (<10 ohm-m) layer at ~1.5 km above a more resistive layer (>1000 ohm-m) at ~ 3.5-4 km. Conductivities of the major stratigraphic units have been determined from well logs and previous MT modeling. Forward and inverse MT models constrained by the gravity-modeled geologic cross section are used to develop a conductivity model consistent with the geology, and are a step towards a better unified treatment of MT, seismic and gravity data.

  8. Seasonal variation of clogging of an artificial recharge basin in a northern climate

    NASA Astrophysics Data System (ADS)

    Schuh, W. M.

    1990-12-01

    The decrease of infiltration rate, and the depth, cause, and hydraulic effect of clogging, were evaluated for a sandy, artificial-recharge test basin during the application of water containing between 51 and 61 mg l -1 suspended solids. Infiltration rate decreased by two orders of magnitude under fall operational conditions for a clean sand surface. Clogging was caused by clay deposition within the basin soil profile during early operation times (19-75 h) followed by the complete interception of sediment in the surface filter cake during later operational times. Impedance decreased by two to three orders of magnitude in the surface 8 cm, and by zero to two orders of magnitude from 8 to 38 cm. Increased clay content following basin operation was measured to a depth of 5 cm. During the spring test, sediment movement and deposition were similar to the fall test. In addition, carbonates and iron oxyhydroxides precipitated, causing cementation of the surface soil grains. The cementation caused increased hydraulic impedance and resulted in a decrease of total recharge. Carbonate precipitation was caused by increased basin-water pH resulting from algal photosynthesis. Allowing the basin to dry and crack for ten days resulted in a substantial recovery (64%) of infiltration rate. Following the drying treatment the basin reclogged more quickly than for the previous test on clean sands, and the impedance of the surface layer reached values larger than those prior to the drying treatment. The decrease of impedance caused by drying was confined to the surface layer, and no effect was observed below 8 cm. Following the natural drying treatment, total recharge was about half that of the clean basin.

  9. Late Permian topography at the southern margin of the Northern Permian Basin: Paleogeography inferred from 3D seismic analysis

    NASA Astrophysics Data System (ADS)

    Clausen, Ole R.; Andresen, Katrine J.; Rasmussen, Jens A.

    2013-04-01

    The Top Pre Zechstein (TPZ) surface in the North Sea Basin is often mapped because it reveals the total basement tectonics in the area. In areas where Zechstein salt is present halokinetic processes, differential subsidence, and Mesozoic faulting however significantly alter the TPZ surface. The study area is located at the southern margin of the Northern Permian Basin in the eastern North Sea at the northern flank of the Ringkøbing-Fyn High. This area occurs approximately at the pinch-out line of the late Permian Zechstein salt and constitutes an excellent theater illustrating a range of salt-related problems. The TPZ surface is characterized by an overall NNW-ward dip defining the northern flank of the RFH and is transected by a set of NNW-SSE striking faults, and a E-W striking set of minor faults. Salt structures in the northern part of the study area introduce velocity pull-up (artefacts) at the TPZ surface and furthermore cause intense faulting of the Mesozoic and Cenozoic cover sediments. Pronounced isolated topographic highs similar to hills can be observed in the southern part of the study area where no to very little Zechstein evaporites are present. In the central part where Zechstein evaporites are present, small topographic highs similar to ridges can be observed at the footwall crest of minor faults. The Zechstein evaporites generally onlap towards the south in the study area but in the transitional zone around the hills, onlap from all directions onto the hills is observed. This suggests that the hills reflect paleo-topography developed during sub-aerial exposure before and perhaps during the deposition of the Zechstein sediments. The internal reflections within the hills show that they are composed of southward dipping sediments and very evident erosional truncations can be observed. The hills are aligned parallel to the major E-W striking basement fault, but are not directly associated to faults offsetting the TPZ surface. However, the alignment

  10. A tectogenetic mechanism controlling the evolution of the Texel-IJsselmeer High (northern Netherlands) and adjacent basins

    SciTech Connect

    Rijkers, R.; Geluk, M. )

    1993-09-01

    Geological studies around the Texel-IJsselmeer High have been carried out for the regional subsurface mapping project of the Geological Survey of The Netherlands. The Texel-IJsselmeer High, in the northern part of the Netherlands, is a northwest-southeast-trending structural unit, slightly tilted to the northeast. The geological evolution of the Texel-IJsselmeer High and the adjacent areas can be linked to an extensional tectonic regime during which several Jurassic basins in the Netherlands originated. During the Late Jurassic, the southern border of the Texel-IJsselmeer High was characterized by normal faulting. Main faults are dipping southwest and are generally part of a half-graben structure. Faulting is accompanied by subsidence of the hanging wall (Jurassic basin area), while the footwall (the Texel-IJsselmeer High) is isostatically uplifted and eroded. The proposed model is based on thinning of the lower crust beneath the basins during Jurassic extension by pure shear. This mechanism is coupled locally with shear zones (simple shear) as a result of lower crustal failure. The model is supported by observations on deep regional seismics at the southern margin of the basin area. During the Late Cretaceous/early Tertiary, transpressional intraplate stresses reactivated the structural weakness zones in the lower and upper crust in a reversed way (inversion). During this tectonic inversion the northwest-southeast-trending Texel-IJsselmeer High acted as a buffer zone perpendicular to the direction of maximum principal stress. Paleogeographical studies and geohistory analysis support the proposed tectogenetic model of the Texel-IJsselmeer High.

  11. Genetic sequence stratigraphy of upper Desmoinesian Oswego limestone along northern shelf margin of Anadarko basin, West-Central Oklahoma

    SciTech Connect

    Derstine, T.P.

    1988-01-01

    The Pennsylvania Oswego limestone (upper Desmoinesian) in the vicinity of the northern shelf break of the Anadarko basin contains stratigraphic sequences and associated depositional facies that were controlled by eustatic variations in a slowly subsiding basin. Core descriptions, detailed well-log correlations, and facies maps of Oswego limestone in Dewey and Custer Counties, Oklahoma, supplemented by seismic data along dip profile, define at least two principal stratigraphic sequences separated by regional unconformities. In this area, oil and gas have been produced from phylloid algal-bank deposits that formed at the shelf margin. The algal-bank deposits that contain vuggy and moldic porosity are bound northward by wackestones of shelf facies and southward by tightly calcite-cemented packstones that formed on the seaward margin in relatively high-energy environments. The detailed well-log correlations that consider genetic units illustrate the evolution of these carbonate and locally clastic deposits along Oswego shelf-ramp-basin profiles as a consequence of sea level oscillations. Repeated succession of upward-coarsening shelf wackestones, algal-bank deposits with fringing packstones and scattered terrigenous clastics, and basinal shales are a depositional system tract associated with sea level lowstand. This lowstand system is capped in one of the principal stratigraphic sequences by a thin shale that reflects an episode of rapid relative sea level rise and flooding of the Oswego carbonate shelf. Black shales deposited during this rapid flooding event form a problematic downlapping unit, because terrigenous sediment was evidently supplied from both the Oklahoma-Kansas area to the north and the Wichita-Amarillo high to the south. Highstand carbonate facies system are not present in the shaly cyclic sequences indicating drowning or backstepping of carbonate sources.

  12. Evolution of the Lower Cretaceous Coqen basin in northern Lhasa, central Tibet Plateau: stratigraphy, sedimentology, and detrital zircon geochronology

    NASA Astrophysics Data System (ADS)

    Sun, Gaoyuan; Hu, Xiumian; Sinclair, Hugh; BouDagher-Fadel, Marcelle

    2016-04-01

    potential sources, the Zelong volcanic rocks and the pre-Carboniferous strata within the northern part of the Lhasa terrane are the most possible sources for the Duoni Formation. The evolution of the Early Cretaceous Coqen basin can be indivied into two stags. During Aptian time (~123-115 Ma), the Duoni Formation received materials southward from the Zelong volcanic rocks and the sedimentary basement rocks in the central Lhasa terrane. The basin developed in a retro-arc setting related to the northward subduction of Neo-tethyan oceanic lithosphere, resulting in the occurrence of the Zelong volcanics arc meanwhile. Our data are inconsistent with the foreland basin related to the Lhasa-Qiangtang collision in the north as previous interpreted. During latest Aptian-earliest Cenomanian (~115-98 Ma), the Coqen basin was prevailed by the shallow marine Langshan limestone, developed in a sag basin that developed in the retro side of the Neo-tethyan oceanic lithosphere subduction. The mechinism of this sag basin was the dynamic subsidence resulted from the low-angle or flatted subduction of the Neo-tethyan oceanic lithosphere during this time interval.

  13. Architecture and subsidence history of the intracratonic Hudson Bay Basin, northern Canada

    NASA Astrophysics Data System (ADS)

    Pinet, Nicolas; Lavoie, Denis; Dietrich, Jim; Hu, Kezhen; Keating, Pierre

    2013-10-01

    The Phanerozoic Hudson Bay Basin is a large intracratonic basin that is almost completely encircled by Precambrian rocks of the Canadian Shield. The preserved sedimentary succession is up to 2500 m thick and consists mainly of Upper Ordovician to Upper Devonian limestones, dolostones, evaporites and minor siliciclastics that were deposited in shallow marine conditions. Backstripping, based on new paleontological data and well correlations, reveals an irregular subsidence history marked by several periods of exhumation. In seismic data, the Hudson Bay Basin appears to have a relatively simple geometry, characterized by a lower sedimentary package cut by high-angle faults, overlain by a saucer-shape, essentially underformed upper sedimentary package. Normal (or transtensional) faults imaged on seismic reflection profiles provide clear evidence for crustal extension during deposition of the older sedimentary packages or slightly later, indicating that the basin is, at least partly, extensional in nature. However, significant changes in the depocenter location during the Paleozoic and variable exhumation values required by new maturation data indicate that other mechanisms influenced the subsidence/exhumation history of the basin. In particular, the influence of far-field events and dynamic topography transmitted by large-scale mantle flow in the continental interior (creating long-wavelength tilting and unconformities) is suspected but not yet proven.

  14. Basin Structure Beneath the Santa Rosa Plain, Northern California: Implications for Damage Caused by the 1969 Santa Rosa and 1906 San Francisco Earthquakes

    NASA Astrophysics Data System (ADS)

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

    2007-12-01

    Regional gravity data in the northern San Francisco Bay region reflect a complex basin configuration beneath the Santa Rosa plain that likely contributed to the significant damage to the city of Santa Rosa caused by the 1969 M 5.6, 5.7 Santa Rosa earthquakes and the 1906 M 7.9 San Francisco earthquake. Inversion of these data indicates that the Santa Rosa plain is underlain by two sedimentary basins about 2 km deep separated by the Trenton Ridge, a shallow west-northwest-striking bedrock ridge west of Santa Rosa. The city of Santa Rosa is situated above the 2 km-wide protruding northeast corner of the southern basin where damage from both the 1969 and 1906 earthquakes was concentrated. Using the gravity-defined basin geometry, ground motion simulations of the 1969 and 1906 earthquakes, two events with opposing azimuths, show enhanced ground motions along the northeastern edge of this corner suggesting that basin-edge effects contributed to the concentration of shaking damage in these events. This indicates that basin edge effects will likely contribute to strong shaking in this area during future earthquakes. Characterization of low-velocity basins and their detailed three-dimensional subsurface geometry is an essential component for characterizing the seismic hazard in the northern San Francisco Bay region and elsewhere.

  15. The basement structure below the peat-lignite deposit in the Philippi sub-basin (Northern Greece) inferred by electromagnetic and magnetic methods

    NASA Astrophysics Data System (ADS)

    Gurk, M.; Tougiannidis, N.; Oikonomopoulos, I. K.; Kalisperi, D.

    2015-04-01

    During 2009 and 2010 electromagnetic (EM) soundings and a high-resolution magnetic survey were conducted to study the deeper structure of the peat-lignite deposit in the Philippi sub-basin in Northern Greece. The primary intention of investigating the basement structure of the Philippi sub-basin is to propose the ideal location for a deep and continuous paleoclimate drill site. Data were collected along a 12 km transect (NNE-SSW) through the largest extension of the basin from Krinides at the North to Eleftheroupolis at the South. We used a combined set of Radiomagnetotelluric (RMT), Time Domain Electromagnetic (TEM) and Audiomagnetotelluric (AMT) soundings to derive a 2D model of the electrical resistivity distribution versus depth using a joint inversion approach. This model was then cross correlated with a 2D forward model of magnetic anomaly data. The magnetic survey detected strong anomalies in the North that appeared to have been generated by the Philippi granitoid pluton. All three individual data sets support each other and have jointly been analyzed. From this study we yield an asymmetric graben model of the basin structure that shows maximum thickness (ca. 500 m) in the northern part of the basin leading to a reduction of the thickness to the South. The interface between the basin fill and the bedrock ascend steeply in the North. The overall assessment of the deeper basin structure reveals a detachment system that is in good accordance with previous findings.

  16. Geochemical evidence for Paleozoic oil in Lower Cretaceous O Sandstone, northern Denver basin

    USGS Publications Warehouse

    Clayton, J.L.

    1989-01-01

    Organic geochemical properties of the oil produced from the Lower Cretaceous O sandstone on the eastern flank of the Denver basin indicate that this oil has been derived from a different source rock than other Cretaceous oils in the basin. O sandstone oil is characterized by low pristane/phytane ratio, high isoprenoid/n-alkane ratios, high asphaltene content, high sulfur content, and slight predominance of even-carbon numbered n-alkanes in the C25+ fraction. These features are evidence of a Paleozoic source and indicate a carbonate rock is the likely source. Preliminary source rock evaluation and correlation data suggest that calcareous black shales and marls of Middle Pennsylvanian (Desmoinesian) age are the source of the O sandstone oil. This is the first reported occurrence of oil from Paleozoic source rocks in a Cretaceous reservoir in the Denver basin. -from Author

  17. Block Modeling of Crustal Deformation in the Northern Walker Lane, Western Basin and Range, to Improve Estimates of Seismic Hazard

    NASA Astrophysics Data System (ADS)

    Hammond, W. C.; Kreemer, C.; Blewitt, G.

    2007-05-01

    In the United States, seismic hazard is evaluated officially by the U.S. Geological Survey and published as estimates in the National Seismic Hazard Maps (NSHM) that depict the peak ground shaking at a specific level of likelihood. In the western Great Basin, the 2002 NSHM is based on a combination of seismic, geologic and geodetic data. However, a discrepancy between the deformation rate that is inferred from the geodetic data (e.g. GPS) and geologic data (e.g. slip rates from fault studies) led to the introduction of an ad hoc zone of crustal shear strain in the western Basin and Range. Only then was the shaking risk portrayed in the NSHM consistent with the relative geodetic velocity of the Sierra Nevada microplate with respect to the central Great Basin. Since creation of the 2002 NSHM there has been a rapid increase in the quantity, quality and spatial coverage of GPS data in the western Great Basin, providing a vast improvement on the constraint on the pattern of crustal deformation. Thus geodesy is poised to make a substantial contribution to the spatial localization of seismic hazard in support of the next generation NSHM. In the Walker Lane ~10 mm/yr of relative motion are accommodated as shear and extension along a ~200 km wide and ~1000 km long zone of intracontinental deformation associated with the Pacific/North American plate boundary. We integrate GPS velocities obtained from sites in the continuous BARGEN, PBO, BARD, semi-continuous MAGNET network plus campaign results from numerous published results to constrain block models of crustal deformation. In so doing we estimate slip rates on block-bounding faults that have regional kinematic self-consistency and can be easily incorporated into the USGS algorithms that compute estimates for seismic hazard. Because of the large number and high density of candidate faults, and length of this zone we divide the region into three parts covering the Northern, Central and Southern Walker Lane. We have completed

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

    SciTech Connect

    Sweetzer, Richard; Leslie, Neil

    2008-02-01

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

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

    SciTech Connect

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

    1999-07-01

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

  20. Late Quaternary faulting on the Manas and Hutubi reverse faults in the northern foreland basin of Tian Shan, China

    NASA Astrophysics Data System (ADS)

    Gong, Zhijun; Li, Sheng-Hua; Li, Bo

    2015-08-01

    The Tian Shan Range lies in the actively deforming part of the India-Asia collision zone. In the northern foreland basin of Tian Shan, the strata were intensively deformed by Cenozoic folding and faulting. Slip rate studies along these faults are important for understanding the dynamics of crustal deformation and evaluating the seismic hazards in the region. Two reverse faults (the Manas and Hutubi faults) in the northern foreland basin were investigated. Due to past faulting events along these faults, the terrace treads along the Manas River were ruptured, forming fault scarps several meters in height. Loess deposits were trapped and preserved at the surface ruptures along these scarps. The thickness of the trapped loess is dependent on the size of the ruptures. The minimum and maximum ages of these scarps are constrained by dating the loess preserved at the surface ruptures and the terrace treads, respectively, using the quartz optically stimulated luminescence (OSL) dating technique. Our dating results suggest that the loess trapped at the ruptures was deposited from the early to mid-Holocene at the Hutubi Fault, and from the mid- to late-Holocene at the Manas Fault. The vertical displacements of the faults were evaluated by measuring the topographic profiles across the investigated fault scarps using the differential global position system (DGPS). Our results suggest that, during the late Quaternary in the studied region, the vertical slip rates of the Manas Fault were between ˜ 0.74 mm /yr and ˜ 1.6 mm /yr, while the Hutubi Fault had a much lower vertical slip rate between ˜ 0.34 mm /yr and ˜ 0.40 mm /yr. The tectonic implications of our results are discussed.

  1. New insights into lithology and hydrogeology of the northern Newark Rift Basin

    NASA Astrophysics Data System (ADS)

    Zakharova, N. V.; Goldberg, D. S.; Olsen, P. E.; Kent, D. V.; Morgan, S.; Yang, Q.; Stute, M.; Matter, J. M.

    2016-06-01

    The marginal facies of the Triassic rift basins in the eastern United States are poorly documented, particularly on the hinge or hanging wall margins. This study presents a lithological description and multiscale petrophysical analysis of basement rocks, overlying marginal facies of the early synrift strata, and the basal contact of the Palisade Sill that were drilled and cored in the northeastern part of the Newark Basin, near its terminus. The expression of the Stockton Formation differs from that in the central basin in having thinner layers, with uncertain temporal relationship to the type area. The bottom 50 m is lithologically distinct with brick-red to dark-purple mudstones and sandstones, abundant gypsum-filled fractures, and a thin zone with anomalously high uranium concentration, not associated with organic-rich mudstones as other occurrences in the basin. The crystalline basement is apparently Fordham gneiss, overlain by a thin sandstone layer and a dark-purple hydrophilic mudstone. Despite the abundance of coarse-grained strata and multiple sets of tectonic fractures, hydraulically transmissive zones are sparse, and do not uniquely correlate to fracture and/or matrix characteristics. Enhanced transmissivity may exist along intrusion boundaries due to enhanced thermal fracturing, but more hydraulic data are needed to verify it. Comparison of petrophysical data in two boreholes ˜210 m apart shows no direct correlation of individual lithological units and their hydraulic properties, although the overall formation characteristics are similar. The results highlight challenges for outcrop correlation at the marginal edges of the rift basins and estimating reservoir properties of these heterogeneous formations.

  2. Innovative Methodology For Detection of Fracture-Controlled Sweet Spots in the Northern Appalachian Basin

    SciTech Connect

    Jacobi, Rober

    2007-03-28

    This Topical Report (#6 of 9) consists of the figures 3.6-13 to (and including) 3.6-18 (and appropriate figure captions) that accompany the Final Technical Progress Report entitled: “Innovative Methodology for Detection of Fracture-Controlled Sweet Spots in the Northern Appalachian Basin” for DOE/NETL Award DE-AC26-00NT40698.

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

    SciTech Connect

    Jacobi, Rober

    2007-03-31

    This Topical Report (#6 of 9) consists of the figures 3.6-13 to (and including) 3.6-18 (and appropriate figure captions) that accompany the Final Technical Progress Report entitled: "Fracture-Controlled Sweet Spots in the Northern Appalachian Basin” for DOE/NETL Award DE-AC26-00NT40698.

  4. Interaction between regional and local tectonic forcing along a complex Quaternary extensional basin: Upper Tiber Valley, Northern Apennines, Italy

    NASA Astrophysics Data System (ADS)

    Pucci, S.; Mirabella, F.; Pazzaglia, F.; Barchi, M. R.; Melelli, L.; Tuccimei, P.; Soligo, M.; Saccucci, L.

    2014-10-01

    In extending areas undergoing regional tectonic uplift, the persistence of subsidence at a normal-fault hanging-wall depends on the competition between regional and local tectonic effects. When regional uplift exceeds the subsidence of the hanging-wall block, denudation prevails at both the hanging-wall and the foot-wall. When local tectonic subsidence exceeds regional uplift, sedimentation occurs over the hanging-wall block, supplied by foot-wall erosion. We analyzed a Pliocene-Quaternary continental basin, currently crossed by the Tiber River in Italy. The tectono-sedimentary evolution of the basin developed at the hanging-wall of a regional low-angle extensional detachment, the Alto Tiberina Fault, in the axial region of the Northern Apennines of Italy. This area is affected by regional uplift on the order of 0.5-1.0 mm/yr. The present-day activity of the fault is revealed by both microseismicity and geodetic (GPS) data. We investigated the mid- (10-100 ka) and long-term (0.5-3.0 Ma) evolution of the three depocenters by studying the continental Pleistocene succession infilling the basin as well as fluvial terraces and higher paleosurfaces carved into the Pleistocene deposits. By using surficial geologic data and an interpretation of a set of seismic reflection profiles, we show that the three depocenters experienced a fairly similar evolution during the Pliocene-Early Pleistocene, when a 1000-m-thick continental succession was deposited. On the contrary, geomorphological observations indicate that, at the beginning of the Middle Pleistocene, a switch occurred in the evolution of the three depocenters. In the northernmost Sansepolcro sub-basin, bounding normal faults are active and hanging-wall subsidence outpaces regional uplift. Concurrently, in the Umbertide and Ponte Pattoli sub-basins uplift dominates over the hanging-wall subsidence, promoting river incision and exhumation of the Pleistocene deposits. For these two depocenters, by means of terrace

  5. Flood-tracking chart for the Withlacoochee and Little River Basins in south-central Georgia and northern Florida

    USGS Publications Warehouse

    Gotvald, Anthony J.; McCallum, Brian E.; Painter, Jaime A.

    2014-01-01

    The U.S. Geological Survey (USGS), in cooperation with other Federal, State, and local agencies, operates a flood-monitoring system in the Withlacoochee and Little River Basins. This system is a network of automated river stage stations (ten are shown on page 2 of this publication) that transmit stage data through satellite telemetry to the USGS in Atlanta, Georgia and the National Weather Service (NWS) in Peachtree City, Georgia. During floods, the public and emergency response agencies use this information to make decisions about road closures, evacuations, and other public safety issues. This Withlacoochee and Little River Basins flood-tracking chart can be used by local citizens and emergency response personnel to record the latest river stage and predicted flood-crest information along the Withlacoochee River, Little River, and Okapilco Creek in south-central Georgia and northern Florida. By comparing the current stage (water-surface level above a datum) and predicted flood crest to the recorded peak stages of previous floods, emergency response personnel and residents can make informed decisions concerning the threat to life and property.

  6. [Assessment of heavy metal pollution in surface sediments of rivers in northern area of Haihe River Basin, China].

    PubMed

    Shang, Lin-Yuan; Sun, Ran-Hao; Wang, Zhao-Ming; Ji, Yu-He; Chen, Li-Ding

    2012-02-01

    Using Håkanson potential ecological risk index, the paper assesses heavy metal risk levels in northern parts of Haihe River basin based on 39 sampling sites. The results indicate that, the concentrations of Cu, Zn, Cd, and Cr in Haihe River basin are higher than the background values of heavy metals in China mainland, while the concentration of Pb is close to the background value in China mainland. Based on the potential ecological risk index for single heavy metal, the risk of Cu, Pb, Zn and Cr belongs to the "slight" level, while Cd has various risk levels at different sampling sites. Generally, the risk order of the heavy metals is Cd > Pb > Cu > Cr > Zn. According to Håkanson potential ecological risk index, 32 monitoring sites belong to "slight" level, 5 sampling sites belong to "middle" level, and 2 monitoring sites belong to "very strong" level. The most polluted sites are Tang River and Dashi River of Beijing, Juma River in Baoding. Therefore, these rivers should be taken more considerations in the river management.

  7. A Systematic Regional Trend in Helium Isotopes Across the NorthernBasin and Range Province, Western North America

    SciTech Connect

    Kennedy, B. Mack; van Soest, Matthijs C.

    2005-03-22

    An extensive study of helium isotopes in fluids collectedfrom surface springs, fumaroles and wells across the northern Basin andRange Province reveals a systematic trend of decreasing 3He/4He ratiosfrom west to east. The western margin of the Basin and Range ischaracterized by mantle-like ratios (6-8 Ra) associated with active orrecently active crustal magma systems (e.g. Coso, Long Valley, Steamboat,and the Cascade volcanic complex). Moving towards the east, the ratiosdecline systematically to a background value of ~;0.1 Ra. The regionaltrend is consistent with extensive mantle melting concentrated along thewestern margin and is coincident with an east-to-west increase in themagnitude of northwest strain. The increase in shear strain enhancescrustal permeability resulting in high vertical fluid flow rates thatpreserve the high helium isotope ratios at the surface. Superimposed onthe regional trend are "helium spikes", local anomalies in the heliumisotope composition. These "spikes" reflect either local zones of mantlemelting or locally enhanced crustal permeability. In the case of theDixie Valley hydrothermal system, it appears to be a combination ofboth.

  8. Enigmatic uppermost Permian-lowermost Triassic stratigraphic relations in the northern Bighorn basin of Wyoming and Montana

    SciTech Connect

    Paull, R.A.; Paull, R.K. )

    1991-06-01

    Eighteen measured sections in the northern Bighorn basin of Wyoming and Montana provide the basis for an analysis of Permian-Triassic stratigraphic relations. This boundary is well defined to the south where gray calcareous siltstones of the Lower Triassic Dinwoody disconformably overlie the Upper Permian Ervay Member of the Park City Formation with little physical evidence of a significant hiatus. The Dinwoody is gradationally overlain by red beds of the Red Peak Formation. The Dinwoody this to zero near the state line. Northward, the erathem boundary is enigmatic because fossils are absent and there is no evidence of an unconformity. Poor and discontinuous exposures contribute to the problem. Up to 20 m of Permian or Triassic rocks or both overlie the Pennsylvanian Tensleep Sandstone in the westernmost surface exposures on the eastern flank of the Bighorn basin with physical evidence of an unconformity. East of the exposed Tensleep, Ervay-like carbonates are overlain by about 15 m of Dinwoody-like siltstones interbedded with red beds and thin dolomitic limestone. In both areas, they are overlain by the Red Peak Formation. Thin carbonates within the Dinwoody are silty, coarse algal laminates with associated peloidal micrite. Carbonates north of the Dinwoody termination and above probably Ervay are peloidal algal laminates with fenestral fabric and sparse coated shell fragments with pisoids. These rocks may be Dinwoody equivalents or they may be of younger Permian age than the Ervay. Regardless, revision of stratigraphic nomenclature in this area may bed required.

  9. High-resolution shallow reflection seismic image and surface evidence of the Upper Tiber Basin active faults (Northern Apennines, Italy)

    USGS Publications Warehouse

    Donne, D.D.; Plccardi, L.; Odum, J.K.; Stephenson, W.J.; Williams, R.A.

    2007-01-01

    Shallow seismic reflection prospecting has been carried out in order to investigate the faults that bound to the southwest and northeast the Quaternary Upper Tiber Basin (Northern Apennines, Italy). On the northeastern margin of the basin a ??? 1 km long reflection seismic profile images a fault segment and the associated up to 100 meters thick sediment wedge. Across the southwestern margin a 0.5 km-long seismic profile images a 50-55??-dipping extensional fault, that projects to the scarp at the base of the range-front, and against which a 100 m thick syn-tectonic sediment wedge has formed. The integration of surface and sub-surface data allows to estimate at least 190 meters of vertical displacement along the fault and a slip rate around 0.25 m/kyr. Southwestern fault might also be interpreted as the main splay structure of regional Alto Tiberina extensional fault. At last, the 1917 Monterchi earthquake (Imax=X, Boschi et alii, 2000) is correlable with an activation of the southwestern fault, and thus suggesting the seismogenic character of this latter.

  10. Introduction to special section on the Northern Chugach Mountains-Southern Copper River Basin Segment of the Alaskan Transect

    NASA Astrophysics Data System (ADS)

    Page, Robert A.

    1989-11-01

    This special section of the Journal of Geophysical Research is the second part of a collection of papers on the nature and evolution of the lithosphere in southern Alaska, specifically beneath the Chugach Mountains and Copper River Basin. The studies in this collection were conducted under the Trans-Alaska Lithosphere Investigation [Stone et al., 1986]: a coordinated geological and geophysical transect of the Alaskan lithosphere along the north-south, trans-Alaska oil pipeline corridor between Valdez and Prudhoe Bay and across the Pacific and Arctic continental margins. The Trans-Alaska Crustal Transect (TACT) project of the U.S. Geological Survey was the primary source of support for these studies, including all the seismic refraction and reflection profiling and most of the geologic field investigations. The first part of the collection appeared in the April 1989 issue and focused on the geology and tectonics of the northern Chugach Mountains and southern Copper River Basin and on the interpretation of a 107-km-long seismic reflection profile along the transect. Appended to those papers, but not included in the introduction [Page, 1989], was an interpretation of the upper crustal structure of the Chugach terrane derived from a transverse (east-west) seismic refraction profile along the axis of the Chugach Mountains [Wolf and Levander, 1989].

  11. An integrated quantitative basin analysis study of the northern part of the Arctic national Wildlife Refuge, Northeastern Alaska

    NASA Astrophysics Data System (ADS)

    Yu, Z.; Lerche, Ian

    1992-06-01

    An integrated basin analysis was conducted using one- and two-dimensional quantitative dynamic models (1-D and 2-D) in the northern part of the Arctic National Wildlife Refuge (ANWR), Northeastern Alaska. Exploratory well data have been used in the reconstructions of: (1) geohistory including basement subsidence, sediment deposition, change of porosity and compaction, permeability, fluid pressure and fluid flow with time and depth; (2) thermal history including heat flux evolution with time, temperature change with time and depth, and thermal maturation history; and (3) hydrocarbon generation history including the change in the amount of hydrocarbons generated with time and depth, and determining the time and depth of peak hydrocarbon generation. 1-D and 2-D basin modeling codes were used with selected wells, and also with a 18 km section, west of ANWR, with five well controls. It is concluded that: (1) the main source rock west of ANWR area matured first about 40-30 Ma ago in the south and gradually to the north about 10-8 Ma ago on the coastal plain; (2) the modeled erosion thickness at Beli Unit-1 location, northeastern Brooks Range, was 1500-3000 m and at least 3000 m at Canning River Unit B-1; and (3) an overpressure zone within the Hue shale and the lowest part of the Canning Formation caused by rapid Tertiary deposition retained porosity, increased the temperature and speeded hydrocarbon generation in the lower part of the coastal plain.

  12. Geohydrologic feasibility study of the Northern and Central Appalachian basin areas for the potential application of a production process patented by Jack W. McIntyre

    SciTech Connect

    Kvasnicka, D.

    1994-03-01

    Geraghty & Miller, Inc. of Midland, Texas conducted geologic and hydrologic feasibility studies of the potential applicability of a patented (US Patent Office No. 4,766,957) process developed by Jack W. McIntyre for the recovery of natural gas from coalbed/sand formations in the Northern and Central Appalachian basin areas. General research, based on a review of published literature from both public and private sources, indicates that the generally thin, but numerous coalbeds found in the greater Appalachian Basin area do exhibit some potential for the application of this patented process. Estimates of total gas reserves in-place (Gas Research Institute, July 1991) for coalbeds in the Central and Northern Appalachian Basin areas are 5 trillion cubic feet (TCF) and 61 TCF respectively. Produced waters associated with coal deposits in the greater Appalachian Basin area can be characterized on the basis of established but limited production of coalbed methane. Central Appalachian coals generally produce small quantities of water (less than 50 barrels of water per day for the average producing well) which is high in total dissolved solids (TDS), greater than 30,000 parts per million (ppM). The chemical quality of water produced from these coal seams represents a significant disposal challenge to the operators of methane-producing wells in the Central Appalachian Basin. By contrast, water associated with the production of coalbed methane in the Northern Appalachian Basin is generally fair to good quality, and daily production volumes are low. However, the relatively slow desorption of methane gas from Northern Appalachian coals may result in a greater net volume of produced water over the economic life of the well. The well operator must respond to long-term disposal needs.

  13. Age and tectonic significance of volcanic rocks in the northern Los Angeles Basin, California

    USGS Publications Warehouse

    McCulloh, Thane H.; Fleck, Robert J.; Denison, Rodger E.; Beyer, Larry A.; Stanley, Richard G.

    2002-01-01

    Volcanic rocks, mostly basalts and some andesites, are interbedded with middle Miocene strata and are overlain by younger rocks throughout the greater part of the Los Angeles Basin, California. Roughly correlative flows, previously dated radiometrically (or paleontologically) at about 16.4 to 10.7 Ma, crop out in five separate regions around the basin perimeter. Los Angeles Basin volcanic rocks have special meaning because they offer clues to tectonomagmatic events associated with onset of clockwise transrotation of the western Transverse Ranges region and to the timing and locus of the initial basin opening. Whole-rock 40Ar/39Ar dating of near-tholeiitic olivine basalts of the Topanga Formation (Hoots, 1931) from three sites in the easternmost Santa Monica Mountains, combined with 87Sr/86Sr dating of fossil carbonates from interstratified marine beds at nine sites, establish a new age of 17.4 Ma for these oldest known Topanga-age volcanics of the Los Angeles Basin. We also record three new 40Ar/39Ar ages (15.3 Ma) from andesitic flows of the lower Glendora Volcanics at the northeast edge of the basin, 70 km east of the Santa Monica Mountains. A whole-rock determination of 17.2±0.5 Ma for nearby altered olivine basalt in the unfossiliferous Glendora volcanic sequence is questionable because of a complex 40Ar/39Ar age spectrum suggestive of 39Ar recoil, but it may indicate an older volcanic unit in this eastern area. We hypothesize that the 17.4-Ma volcanics in the eastern Santa Monica Mountains are an early expression of deep crustal magmatism accompanying the earliest extensional tectonism associated with rifting. The extremely thick younger volcanic pile in the western and central parts of the range may suggest that this early igneous activity in the eastern area was premonitory. Paleomagnetic declination data are needed to determine the pre-transrotational orientation of the eastern Santa Monica Mountains volcanic sequence. The new age determinations do not

  14. Trends in annual and extreme flows in the Lena River basin, Northern Eurasia

    NASA Astrophysics Data System (ADS)

    Tananaev, N. I.; Makarieva, O. M.; Lebedeva, L. S.

    2016-10-01

    A long-term daily streamflow data set, covering the period from 1925 to 2013, was compiled for the Lena River basin, with an average record length of 49 years. Time series of mean annual daily flow (MADF) and extreme (maximum, Qmax, and minimum, Qmin) daily flows were subject to trend detection and change point detection analysis. Significant changes result mostly from rapid "breakpoint" homogeneity disruptions. Thirty one time series showed trends in MADF, 10, in Qmax, and 32 of the 55 records with nonzero Qmin, significant at p ≤ 0.05. Upward trends prevail in both mean annual and extreme flows, with average magnitudes of 47% (MADF), 56% (Qmax), and 68% (Qmin). Two to three stations in each subset showed downward trends (averaging -20%, -39%, and -38%, respectively). Abrupt changes are observed in the 1990s and early 2000s mostly in the headwaters of the basin, underlain by discontinuous permafrost.

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

    NASA Astrophysics Data System (ADS)

    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

  16. Carbonate and lignite cycles in the Ptolemais Basin: Orbital control and suborbital variability (Late Neogene, northern Greece)

    NASA Astrophysics Data System (ADS)

    Weber, M. E.; Tougiannidis, N.; Ricken, W.; Rolf, C.; Kleineder, M.; Bertram, N.; Antoniadis, P.

    2009-04-01

    We recently commenced a project to investigate deep drillings as well as outcrops in the Ptolemais Basin, northern Greece, for paleoenvironmental and paleoclimate change. Specific attention is paid to mining sites Achlada, Vevi, Vegora, Amynteon, North Field, South Field, and Lava. The sediment archive comprises Upper Miocene to Quaternary continental lake deposits (up to 800 m thick) with an extended Lower Pliocene section. The Upper Miocene sections are composed of diatomaceous mud and gray marls. Pliocene lake sediments commence with the Kyrio member (lignite/grey marl), followed by the Theodoxus member (beige marl/lignite), and the Notio member (marl with intercalated sand /lignite). The limnic deposits show striking rhythmic bedding of (mostly) carbonates and lignites, reflecting orbital-induced humidity and temperature changes in this small NW-SE elongated continental basin. First, we retrieved chronometric information by determining magnetic polarity changes on three sites as independent stratigraphic ground-truth in combination with palynological evidence and published data. Then we conducted a number of high-resolution (1 - 6 cm increment), non-destructive measurements to obtain paleoclimate proxies: photospectrometry (colors L, a, b), magnetic susceptibility, and natural gamma. Accordingly, we achieved a multi-proxy insight into paleoclimate and paleoenvironmental evolution at unprecedented temporal resolution (up to a few decades!) over long time series and at a number of key sites. Using the newly-developed ESALab software, we conducted spectral and evolutionary spectral analysis to evaluate the cyclo-stratigraphic development. As for orbital variability, spectral power is concentrated on precession, hemi-precession, and eccentricity, with only minor impact of orbital tilt. We used this information to increase the temporal resolution of our age models by tuning as many precession (insolation) maxima as possible to carbonate minima (lignite maxima

  17. Heavy metal accumulation by periphyton is related to eutrophication in the Hai River Basin, Northern China.

    PubMed

    Tang, Wenzhong; Cui, Jingguo; Shan, Baoqing; Wang, Chao; Zhang, Wenqiang

    2014-01-01

    The Hai River Basin (HRB) is one of the most polluted river basins in China. The basin suffers from various types of pollutants including heavy metals and nutrients due to a high population density and rapid economic development in this area. We assessed the relationship between heavy metal accumulation by periphyton playing an important role in fluvial food webs and eutrophication in the HRB. The concentrations of the unicellular diatoms (type A), filamentous algae with diatoms (type B), and filamentous algae (type C) varied along the river, with type A dominating upstream, and types B then C increasing in concentration further downstream, and this was consistent with changes in the trophic status of the river. The mean heavy metal concentrations in the type A, B and C organisms were Cr: 18, 18 and 24 mg/kg, respectively, Ni: 9.2, 10 and 12 mg/kg, respectively, Cu: 8.4, 19 and 29 mg/kg, respectively, and Pb: 11, 9.8 and 7.1 mg/kg respectively. The bioconcentration factors showed that the abilities of the organisms to accumulate Cr, Ni and Pb decreased in the order type A, type B, then type C, but their abilities to accumulate Cu increased in that order. The Ni concentration was a good predictor of Cr, Cu and Pb accumulation by all three periphyton types. Our study shows that heavy metal accumulation by periphyton is associated with eutrophication in the rivers in the HRB.

  18. Temporal and spatial distribution of landslides in the Redwood Creek Basin, Northern California

    USGS Publications Warehouse

    Madej, Mary Ann; Medley, C. Nicholas; Patterson, Glenn; Parker, Melanie J.

    2011-01-01

    Mass movement processes are a dominant means of supplying sediment to mountainous rivers of north coastal California, but the episodic nature of landslides represents a challenge to interpreting patterns of slope instability. This study compares two major landslide events occurring in 1964-1975 and in 1997 in the Redwood Creek basin in north coastal California. In 1997, a moderate-intensity, long-duration storm with high antecedent precipitation triggered 317 landslides with areas greater than 400 m2 in the 720-km2 Redwood Creek basin. The intensity-duration threshold for landslide initiation in 1997 was consistent with previously published values. Aerial photographs (1:6,000 scale) taken a few months after the 1997 storm facilitated the mapping of shallow debris slides, debris flows, and bank failures. The magnitude and location of the 1997 landslides were compared to the distributions of landslides generated by larger floods in 1964, 1972, and 1975. The volume of landslide material produced by the 1997 storm was an order of magnitude less than that generated in the earlier period. During both periods, inner gorge hillslopes produced many landslides, but the relative contribution of tributary basins to overall landslide production differed. Slope stability models can help identify areas susceptible to failure. The 22 percent of the watershed area classified as moderately to highly unstable by the SHALSTAB slope stability model included locations that generated almost 90 percent of the landslide volume during the 1997 storm.

  19. Heavy Metal Accumulation by Periphyton Is Related to Eutrophication in the Hai River Basin, Northern China

    PubMed Central

    Tang, Wenzhong; Cui, Jingguo; Shan, Baoqing; Wang, Chao; Zhang, Wenqiang

    2014-01-01

    The Hai River Basin (HRB) is one of the most polluted river basins in China. The basin suffers from various types of pollutants including heavy metals and nutrients due to a high population density and rapid economic development in this area. We assessed the relationship between heavy metal accumulation by periphyton playing an important role in fluvial food webs and eutrophication in the HRB. The concentrations of the unicellular diatoms (type A), filamentous algae with diatoms (type B), and filamentous algae (type C) varied along the river, with type A dominating upstream, and types B then C increasing in concentration further downstream, and this was consistent with changes in the trophic status of the river. The mean heavy metal concentrations in the type A, B and C organisms were Cr: 18, 18 and 24 mg/kg, respectively, Ni: 9.2, 10 and 12 mg/kg, respectively, Cu: 8.4, 19 and 29 mg/kg, respectively, and Pb: 11, 9.8 and 7.1 mg/kg respectively. The bioconcentration factors showed that the abilities of the organisms to accumulate Cr, Ni and Pb decreased in the order type A, type B, then type C, but their abilities to accumulate Cu increased in that order. The Ni concentration was a good predictor of Cr, Cu and Pb accumulation by all three periphyton types. Our study shows that heavy metal accumulation by periphyton is associated with eutrophication in the rivers in the HRB. PMID:24482681

  20. Morphotectonic characteristics of a propagating spreading system in the northern Lau Basin

    NASA Astrophysics Data System (ADS)

    Wiedicke, Michael; Habler, Walter

    1993-07-01

    Bathymetric Sea Beam mapping of a southward propagating rift system in the Lau Basin (SW Pacific) shows a morphotectonic segmentation of the two competing axes: Over a distance of 70 km the propagating axis develops from a narrow rift graben at the propagator tip, via a leaky graben, into a juvenile volcanic ridge, and finally into a fully developed spreading ridge. The competing dying spreading axis 70 km farther east shows steady deepening towards the north, combined with a change from a small volcanic ridge to a narrow depression before it is buried by sediments. The relay zone between the two axes contains two deep N-S striking grabens; the eastern one, 3200 m deep, may act as a short-lived spreading center. A NE-trending string of slightly offset deep sediment-filled basins is interpreted as fossil analogs to these grabens, originally generated in the southward migrated relay zone. The string of basins suggests an episodic rather than steady state southward migration. Propagation and opening of grabens led to a rotation of the inherited ridge-parallel crustal fabric. However, the propagating tip and the grabens cut obliquely through the fabric thus generating small-scale structural and morphological inhomogeneities of the crust. At the propagating tip, old and new tectonic lineaments closely interfinger.

  1. Water resources: the prerequisite for ecological restoration of rivers in the Hai River Basin, northern China.

    PubMed

    Tang, Wenzhong; Mao, Zhanpo; Zhang, Hong; Shan, Baoqing; Zhao, Yu; Ding, Yuekui

    2015-01-01

    The competition for water resources between humans and river ecosystems is becoming ever more intense worldwide, especially in developing countries. In China, with rapid socioeconomic development, water resources to maintain river ecosystems are progressively decreasing, especially in the Hai River Basin (HRB), which has attracted much attention from the Chinese government. In the past 56 years, water resources have continuously decreased in the basin, such that there is 54.2 % less surface water now compared with then. Water shortages, mainly due to local anthropogenic activities, have emerged as the main limiting factor to river ecological restoration in the HRB. However, the South-to-North Water Diversion Project, the largest such project in the world, presents a good opportunity for ecological restoration of rivers in this basin. Water diverted from the Danjiangkou Reservoir will restore surface water resources in the HRB to levels of 30 years ago and will amount to more than 20 billion m(3). Our findings highlight the fact that water resources are crucial for river ecological restoration.

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

    SciTech Connect

    Ramon, J.C. ); Dzou, L. )

    1996-01-01

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

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

    USGS Publications Warehouse

    Nash, J. Thomas

    2005-01-01

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

  4. Timing of Cenozoic volcanism and Basin and Range extension in northwestern Nevada: New constraints from the northern Pine Forest Range

    USGS Publications Warehouse

    Colgan, J.P.; Dumitru, T.A.; McWilliams, M.; Miller, E.L.

    2006-01-01

    Eocene-middle Miocene volcanic rocks in the northern Pine Forest Range, Nevada, are ideally situated for reconstructing the timing and style of volcanism and extensional faulting in the northwesternmost part of the Basin and Range province. A conformable sequence of Cenozoic volcanic and sedimentary strata in the northern Pine Forest Range dips ???30??W, and 11 new 40Ar/39Ar ages from this sequence define 3 major episodes of volcanic activity. Pre-Tertiary basement and older (ca. 38 Ma) Tertiary intrusive rocks are overlain unconformably by Oligocene (ca. 30-23 Ma) basalt flows and dacitic to rhyolitic ash-flow tuffs interbedded with fine-grained tuffaceous sedimentary rocks. Oligocene rocks are overlain by ???550 m of ca. 17-16 Ma basalt flows equivalent to the Steens Basalt in southern Oregon, and basalt flows are capped by a thin 16.3 Ma ignimbrite that likely is correlative with either the Idaho Canyon Tuff or the Tuff of Oregon Canyon. The northern Pine Forest Range is bounded to the east by a major down-to-the-east normal fault that dips ???40??E with well-developed fault striations indicative of dip-slip motion. This fault initiated at an angle of ???70?? and was rotated ???30?? during uplift of the range. A suite of 17 apatite fission-track ages from the Pine Forest footwall block demonstrates that exhumation, uplift, and slip on the range-bounding fault began ca. 12-11 Ma and continued until at least 7 Ma, with moderate slip since then. The Pine Forest Range did not undergo significant extension before or during peak Oligocene and Miocene volcanism, and similar geologic relationships in nearby ranges suggest that a larger region of northwestern Nevada was also little extended during this interval. Basin and Range faulting in northwestern Nevada appears to have begun no earlier than 12 Ma, making it distinctly younger than deformation in much of central and southern Nevada, where peak extension occurred in the middle Miocene or earlier. ?? 2006 Geological

  5. BASINS

    EPA Pesticide Factsheets

    Better Assessment Science Integrating Point and Nonpoint Sources (BASINS) is a multipurpose environmental analysis system designed to help regional, state, and local agencies perform watershed- and water quality-based studies.

  6. Effects of anthropogenic groundwater exploitation on land surface processes: A case study of the Haihe River Basin, northern China

    NASA Astrophysics Data System (ADS)

    Zou, Jing; Xie, Zhenghui; Zhan, Chesheng; Qin, Peihua; Sun, Qin; Jia, Binghao; Xia, Jun

    2015-05-01

    In this study, we incorporated a groundwater exploitation scheme into the land surface model CLM3.5 to investigate the effects of the anthropogenic exploitation of groundwater on land surface processes in a river basin. Simulations of the Haihe River Basin in northern China were conducted for the years 1965-2000 using the model. A control simulation without exploitation and three exploitation simulations with different water demands derived from socioeconomic data related to the Basin were conducted. The results showed that groundwater exploitation for human activities resulted in increased wetting and cooling effects at the land surface and reduced groundwater storage. A lowering of the groundwater table, increased upper soil moisture, reduced 2 m air temperature, and enhanced latent heat flux were detected by the end of the simulated period, and the changes at the land surface were related linearly to the water demands. To determine the possible responses of the land surface processes in extreme cases (i.e., in which the exploitation process either continued or ceased), additional hypothetical simulations for the coming 200 years with constant climate forcing were conducted, regardless of changes in climate. The simulations revealed that the local groundwater storage on the plains could not contend with high-intensity exploitation for long if the exploitation process continues at the current rate. Changes attributable to groundwater exploitation reached extreme values and then weakened within decades with the depletion of groundwater resources and the exploitation process will therefore cease. However, if exploitation is stopped completely to allow groundwater to recover, drying and warming effects, such as increased temperature, reduced soil moisture, and reduced total runoff, would occur in the Basin within the early decades of the simulation period. The effects of exploitation will then gradually disappear, and the variables will approach the natural state and

  7. Hydrothermal activity along the northern Mid-Atlantic Ridge and in the Bransfield Strait Backarc Basin, Antarctica

    NASA Astrophysics Data System (ADS)

    Chin, Carol S.

    1998-12-01

    Seafloor hydrothermal circulation through young oceanic crust results in the expulsion of fluids as both diffuse and focused flow in the form of hydrothermal venting. High-temperature hydrothermal fluids are enriched in reduced chemical species that rapidly oxidize upon interaction with ambient, oxygen-rich bottom waters, resulting in plumes that are detectable in the water column both by their dissolved chemical composition as well as by their particle concentration. This study employed a novel instrument package which detected both dissolved manganese and particle concentration in situ. This package also included a standard CTD (conductivity, temperature, depth) and rosette for the collection of water samples. Because hydrothermal plumes integrate the output from an entire vent field, measurements in plumes can be used to estimate vent field fluxes. Some geochemical tracers from hydrothermal vents can also be detected thousands of kilometers from their sources. Thus, plumes provide the means to prospect for undiscovered hydrothermal sites, and can also predict characteristics of the venting site. This work includes studies of hydrothermal plumes along the northern Mid-Atlantic Ridge and in the Bransfield Strait backarc basin, Antarctica. In recent years, the number of known hydrothermal sites on the Mid-Atlantic Ridge (MAR) has increased from two to seven, and most other segments between 12° and 41° N have shown evidence of high-temperature hydrothermal activity. Furthermore, it appears that as one approaches the Azores Plateau, the concentration of dissolved delta3He in the bottom water (originating from hydrothermal venting) increases, suggesting that hydrothermal activity increases toward the plateau. This is consistent with the significant tectonic extension and crustal fissuring observed near the Azores Platform, which is expected to support increased convection. The Bransfield Strait is a backarc basin between the Antarctic Peninsula and the South

  8. Effects of anthropogenic groundwater exploitation on land surface processes: A case study of the Haihe River Basin, Northern China

    NASA Astrophysics Data System (ADS)

    Xie, Z.; Zou, J.; Qin, P.; Sun, Q.

    2014-12-01

    In this study, we incorporated a groundwater exploitation scheme into the land surface model CLM3.5 to investigate the effects of the anthropogenic exploitation of groundwater on land surface processes in a river basin. Simulations of the Haihe River Basin in northern China were conducted for the years 1965-2000 using the model. A control simulation without exploitation and three exploitation simulations with different water demands derived from socioeconomic data related to the Basin were conducted. The results showed that groundwater exploitation for human activities resulted in increased wetting and cooling effects at the land surface and reduced groundwater storage. A lowering of the groundwater table, increased upper soil moisture, reduced 2 m air temperature, and enhanced latent heat flux were detected by the end of the simulated period, and the changes at the land surface were related linearly to the water demands. To determine the possible responses of the land surface processes in extreme cases (i.e., in which the exploitation process either continued or ceased), additional hypothetical simulations for the coming 200 years with constant climate forcing were conducted, regardless of changes in climate. The simulations revealed that the local groundwater storage on the plains could not contend with high-intensity exploitation for long if the exploitation process continues at the current rate. Changes attributable to groundwater exploitation reached extreme values and then weakened within decades with the depletion of groundwater resources and the exploitation process will therefore cease. However, if exploitation is stopped completely to allow groundwater to recover, drying and warming effects, such as increased temperature, reduced soil moisture, and reduced total runoff, would occur in the Basin within the early decades of the simulation period. The effects of exploitation will then gradually disappear, and the land surface variables will approach the

  9. Magnetotelluric studies in and adjacent to the Northumberland Basin, Northern England

    NASA Astrophysics Data System (ADS)

    Parr, R. S.; Hutton, V. R. S.

    1993-12-01

    During the past decade broadband magnetotelluric (MT) soundings, with d.c. resistivity soundings at some sites, have been undertaken in three separate field studies in and around the Northumberland Basin, a region of great interest to earth scientists on account of the proposed location there of the Iapetus Suture. As a result of an increase in cultural noise during this period, the data from the last two studies have been processed using a new robust constrained impedance tensor estimation program. The resulting apparent resistivity and phase data from these studies, together with those from the first broadband study and some earlier MT responses from the region, have now all been modelled using an interpretative modelling procedure. New information has been provided by the MT models on basement depths and, by integrating these new estimates with those from gravity modelling and seismic studies both on land and offshore, a detailed basement topography map has been compiled for the region. The deep eletrical resistivity structure has been modelled along a NW-SE traverse from the Weardale Granite of the Alston Block across the Northumberland Basin to the Southern Uplands of Scotland. Underlying the more conductive sedimentary rocks, the basement rock is found to have resistivities which range from about 100 μ m in the Northumberland Basin to more than 1000 μ m in the Alston Block and probably of the same order in the Southern Uplands. A mid-crustal conductor exists along the whole traverse, which is well resolved and has a southward dip beneath the Weardale Granite. Under the Northumberland Basin, the conductor is less well resolved and thus an apparent northward dip can only be regarded as tentative. Comparison of the pseudo-2D and full 2D models resulting from this study and from earlier MT and magnetovariational (MV) studies in Southern Scotland with new MT and joint MT and MV inversions of Livelybrooks et al. (Phys. Earth Planet. Inter., 81: 67-84 (1993)) for

  10. Late Cenozoic pollen records and paleoclimate in the western Qaidam Basin, Northern Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Miao, Y.

    2013-12-01

    Y. F. Miao1, X. M. Fang2*, F. L. Wu2, M. T. Cai2, C. H. Song3, Q. Q. Meng3 1 Key Laboratory of Desert and Desertification, Cold and Arid Regions Environmental and Engineering Institute, Chinese Academy of Sciences, Lanzhou, 730000, China 2 Key Laboratory of Continental Collision and Plateau Uplift, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, 100085, China 3 School of Earth Science, Lanzhou University, Lanzhou, 730000, China * Corresponding author, E-mail address: fangxm@itpcas.ac.cn (X.M. Fang). Abstract: Cenozoic climate changes in inner Asia provide a basis for understanding linkages between global cooling, the Tibetan Plateau uplift, and possibly the development of the East Asian monsoon. Based on a compilation of palynological results from the western Qaidam Basin, this study reconstructed a 15 million years (Ma) record of changing vegetation and paleoclimates spanning the middle Miocene to present (comprising two series: ~18-5 Ma and ~3.1-0 Ma, respectively). The thermophilic percentages were highest between 18 and 14 Ma, and decreased after 14 Ma, closely corresponding to the Middle Miocene Climatic Optimum (MMCO) between 18 and 14 Ma and the following global climatic cooling between 14 and 5 Ma. At the same time, decreases in the xerophytic and coniferous taxa percentages, and the increasing logarithmic ratio of non-arboreal pollen to arboreal pollen (ln (NAP/AP)), reveal the continuous aridification across both the basin and surrounding mountains. Between ~3.1-0 Ma, the percentages of the thermophilic, xerophytic and coniferous pollen as well as the ln (NAP/AP) imply further cooling and drying in this region since 3.1 Ma. We argue that these vegetation and climate patterns during the late Cenozoic western Qaidam Basin are primarily a result of the global cooling, with the Tibetan Plateau uplift and East Asian summer monsoon having contributions of lesser importance.

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

    PubMed

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

    2015-01-01

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

  12. Geology and water-yielding characteristics of rocks of the northern Powder River basin, southeastern Montana

    USGS Publications Warehouse

    Lewis, Barney D.; Roberts, Robert S.

    1978-01-01

    Numerous and widespread subbituminous and lignite coal deposits occur in the Powder River Basin in southeastern Montana, principally within the Fort Union Formation. Many of the coal beds are less than 250 feet (76.2 m) below land surface and are, therefore, mineable by surface methods. Individual cola beds are commonly 20-30 feet (6.1-9.1 m) thick, but may be as much as 80 feet (24 m). These factors, coupled with the low-sulfur content of the coal, make it attractive as a major energy resource. 

  13. Climatic and Tectonic Controls on Topography in the Northern Basin and Range

    NASA Astrophysics Data System (ADS)

    Foster, D.; Brocklehurst, S. H.; Gawthorpe, R. L.

    2006-12-01

    This study takes advantage of the relatively simple tectonics of the normal fault-bounded Lost River and Lemhi Ranges and the Beaverhead Mountains, eastern Idaho, USA, to assess the roles of climate, erosion, and tectonics in topographic evolution through a combination of digital topographic analyses and field observations. These ranges transect the southern limit of Quaternary glaciation, and drainage basins record a range of glacial extents and histories, allowing for comparisons between climatic and tectonic controls. At a catchment scale, topography is controlled by both the degree of glaciation, and the response of the drainage system to range-front faulting. The range-bounding normal faults are segmented along-strike, and fault uplift rates vary systematically, being greatest at the fault centres. Here catchments predominantly drain normal to the range-front fault, although the trend of some catchments is influenced by pre-existing tectonic fabrics related to Cretaceous (northeast-southwest trending) and early Miocene (northwest-southeast trending) extension. For catchments that drain through fault segment boundaries, one of two general morphologies occurs. Either large drainage basins form, capturing drainage area from neighbouring basins, or, when fault segment boundaries are en echelon, a series of small drainage basins may form as catchments as the inboard- and outboard- footwalls interact and respond to fault linkage. Quaternary glaciation affected all but the southern portions of each of the ranges, most extensively at the north-eastern range flank. Increased extent of glaciation within a catchment results in wider valley floors, steeper valley walls, and greater relief at elevations close to the ELA. Cirque formation occurs preferentially on the north-eastern range flank, where glaciers are sheltered from both solar radiation and snow re-distribution by the prevailing winds. Snow accumulation is promoted in this setting by the increased influx of wind

  14. Multielement geochemical dataset of surficial materials for the northern Great Basin

    USGS Publications Warehouse

    Coombs, Mary Jane; Kotlyar, Boris B.; Ludington, Steve; Folger, Helen W.; Mossotti, Victor G.

    2002-01-01

    This report presents geochemical data generated during mineral and environmental assessments for the Bureau of Land Management in northern Nevada, northeastern California, southeastern Oregon, and southwestern Idaho, along with metadata and map representations of selected elements. The dataset presented here is a compilation of chemical analyses of over 10,200 stream-sediment and soil samples originally collected during the National Uranium Resource Evaluation's (NURE) Hydrogeochemical and Stream Sediment Reconnaissance (HSSR) program of the Department of Energy and its predecessors and reanalyzed to support a series of mineral-resource assessments by the U.S. Geological Survey (USGS). The dataset also includes the analyses of additional samples collected by the USGS in 1992. The sample sites are in southeastern Oregon, southwestern Idaho, northeastern California, and, primarily, in northern Nevada. These samples were collected from 1977 to 1983, before the development of most of the present-day large-scale mining infrastructure in northern Nevada. As such, these data may serve as an important baseline for current and future geoenvironmental studies. Largely because of the very diverse analytical methods used by the NURE HSSR program, the original NURE analyses in this area yielded little useful geochemical information. The Humboldt, Malheur-Jordan-Andrews, and Winnemucca-Surprise studies were designed to provide useful geochemical data via improved analytical methods (lower detection levels and higher precision) and, in the Malheur-Jordan-Andrews and Winnemucca Surprise areas, to collect additional stream-sediment samples to increase sampling coverage. The data are provided in *.xls (Microsoft Excel) and *.csv (comma-separated-value) format. We also present graphically 35 elements, interpolated ("gridded") in a geographic information system (GIS) and overlain by major geologic trends, so that users may view the variation in elemental concentrations over the

  15. Evolution of the Rodgers Creek–Maacama right-lateral fault system and associated basins east of the northward-migrating Mendocino Triple Junction, northern California

    USGS Publications Warehouse

    McLaughlin, Robert J.; Sarna-Wojcicki, Andrei M.; Wagner, David L.; Fleck, Robert J.; Langenheim, V.E.; Jachens, Robert C.; Clahan, Kevin; Allen, James R.

    2012-01-01

    The Rodgers Creek–Maacama fault system in the northern California Coast Ranges (United States) takes up substantial right-lateral motion within the wide transform boundary between the Pacific and North American plates, over a slab window that has opened northward beneath the Coast Ranges. The fault system evolved in several right steps and splays preceded and accompanied by extension, volcanism, and strike-slip basin development. Fault and basin geometries have changed with time, in places with younger basins and faults overprinting older structures. Along-strike and successional changes in fault and basin geometry at the southern end of the fault system probably are adjustments to frequent fault zone reorganizations in response to Mendocino Triple Junction migration and northward transit of a major releasing bend in the northern San Andreas fault. The earliest Rodgers Creek fault zone displacement is interpreted to have occurred ca. 7 Ma along extensional basin-forming faults that splayed northwest from a west-northwest proto-Hayward fault zone, opening a transtensional basin west of Santa Rosa. After ca. 5 Ma, the early transtensional basin was compressed and extensional faults were reactivated as thrusts that uplifted the northeast side of the basin. After ca. 2.78 Ma, the Rodgers Creek fault zone again splayed from the earlier extensional and thrust faults to steeper dipping faults with more north-northwest orientations. In conjunction with the changes in orientation and slip mode, the Rodgers Creek fault zone dextral slip rate increased from ∼2–4 mm/yr 7–3 Ma, to 5–8 mm/yr after 3 Ma. The Maacama fault zone is shown from several data sets to have initiated ca. 3.2 Ma and has slipped right-laterally at ∼5–8 mm/yr since its initiation. The initial Maacama fault zone splayed northeastward from the south end of the Rodgers Creek fault zone, accompanied by the opening of several strike-slip basins, some of which were later uplifted and compressed

  16. Saline-seep development in the Hailstone Basin, northern Stillwater County, Montana

    USGS Publications Warehouse

    Lewis, Barney D.; Custer, Stephen G.; Miller, Marvin R.

    1979-01-01

    As a result of an increase in saline seep occurrence in Montana, a study was begun in 1974 to determine the hydrogeology of saline seeps in the Hailstone basin. The aquifer is composed of colluvium of Holocene age. The impermeable Cretaceous Niobrara Formation underlies the saturated zone basinwide. The ground-water system is shallow, unconfined, and locally recharged. Ground-water levels and size of the saline seeps respond rapidly to precipitation in the basin. The appearance and growth of saline seeps are related to precipitation patterns; the agricultural practice of summer follow; topography; the presence of a shallow, unconfined, and locally recharged ground-water system; and a soluble salt source. Continuous cropping could reduce the amount of water percolating beneath local recharge areas, and thus minimize the water available for seep formation and growth. The lateral variation in chemical quality of water from wells suggests a shallow flow system. The field specific conductance of 29 ground-water samples collected in 1976 ranged from 2,160 to 14,000 micromhos per centimeter and averaged 6,660 micromhos per centimeter. Water from saline seeps in the study area contains principally sodium, magnesium, calcium, and sulfate. Nitrate is present in the ground water in concentrations of as much as 855 milligrams per liter. The high nitrate concentrations are interpreted to originate primarily from oxidation of organic material once native sod is broken by cultivation. (USGS).

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

    USGS Publications Warehouse

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

    1998-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Espinoza, M. E.

    2015-12-01

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

  19. BOLIVAR and GULFREX MCS Data Constrain Closure of the Grenada Backarc Basin During Oblique Collision Between the Lesser Antilles Arc System and Northern South America

    NASA Astrophysics Data System (ADS)

    Aitken, T. J.; Mann, P.; Christeson, G.

    2004-12-01

    The Lesser Antilles evolved from the mid-Cretaceous as an extensional arc system formed above a steeply dipping slab of Atlantic oceanic crust. The arc became extensional during the Paleocene - early Eocene along normal faults at the eastern edge of the basin as the present-day Lesser Antilles chain rifted away from the Aves Ridge. Backarc rifting ceased during the early Eocene, leaving the 140 km wide 3 km deep Grenada backarc basin. Sediment accumulation reached nearly 8 km during the Paleogene with another 1.5 km of sediments accumulating during the Neogene. In this presentation, we combine newly acquired MCS lines from the BOLIVAR study with existing GULFREX data collected in 1975 to document the structural and stratigraphic effects of closure of the Grenada backarc basin because of the progressive, oblique collision between the Lesser Antilles arc system and northern South America. The southern end of the Grenada basin has been narrowed from an undeformed width of approximately 100 km to a deformed width of 30 km, and rotated nearly 90 degrees to the west as the arc system obliquely collides with the South American margin. Shortening of the colliding backarc basin is mainly accommodated by inversion of Paleogene normal faults on the eastern edge of the basin, folding, low-angle thrust faults, and possibly shale diapirism. We propose that this closure in the area is a backthrusting response during Oligocene - late Miocene closure along the leading edge of the oblique arc-continent collision in the Eastern Venezuelan basin.

  20. Architecture of the tectonically influenced Sobrarbe deltaic complex in the Ainsa Basin, northern Spain

    NASA Astrophysics Data System (ADS)

    Dreyer, Tom; Corregidor, Jordi; Arbues, Pau; Puigdefabregas, Cai

    1999-09-01

    The syn-tectonic Sobrarbe deltaic complex (Eocene of the Ainsa Basin, Spanish Pyrenees) is confined by lateral thrust ramps and influenced by intra-basinal growth anticlines. Six facies associations have been distinguished within the deltaic complex: (i) slope marls and turbidite sandstones; (ii) distal delta front silty and bioturbated sandstones; (iii) proximal delta front and delta plain deposits (tidal inlet, tidal flat, mouth-bar, bay, distributary channel, and floodplain environments); (iv) biogenic deposits at flooding surfaces; (v) collapse zone sediments; and (vi) Nummulite-dominated shallow-marine carbonates. The deltaic complex comprises four composite sequences, which each contain a number of minor sequences of the genetic (maximum flooding surface bounded) type. Regressive unconformities and their correlative surfaces separate the composite sequences (CS), and each CS can be divided into lowstand, transgressive and highstand components. At the base, the Comaron CS is a WNW-prograding deltaic complex containing six minor sequences characterized by basinward-stepping sandstone wedges separated by transgressive mudstones. Double regressive unconformities are often associated with these sandstone wedges proximally in the basin. Growth of the intra-basinal Arcusa anticline caused gentle folding of the Comaron CS, and syn-growth strata at the base of the overlying Las Gorgas CS contain a prominent forced regressive sandstone wedge (the Las Gorgas sandbody) and display thinning of bedsets onto the crest of the anticline. Moreover, it can be demonstrated that relative sea-level rise took place in the growth synclines at the same time as a fall in relative sea level occurred on the growth anticlines. The tectonic deformation caused a shift in the direction of deltaic progradation towards the north-northwest, as demonstrated by the well-developed clinoforms in the highstand sequence set of the Las Gorgas CS. A second phase of tectonic activity, this time

  1. Facies analysis, palaeoenvironmental reconstruction and stratigraphic development of the Early Cretaceous sediments (Lower Bima Member) in the Yola Sub-basin, Northern Benue Trough, NE Nigeria

    NASA Astrophysics Data System (ADS)

    Sarki Yandoka, Babangida M.; Abubakar, M. B.; Abdullah, Wan Hasiah; Amir Hassan, M. H.; Adamu, Bappah U.; Jitong, John S.; Aliyu, Abdulkarim H.; Adegoke, Adebanji Kayode

    2014-08-01

    The Benue Trough of Nigeria is a major rift basin formed from the tension generated by the separation of African and South American plates in the Early Cretaceous. It is geographically sub-divided into Southern, Central and Northern Benue portions. The Northern Benue Trough comprises two sub-basins; the N-S trending Gongola Sub-basin and the E-W trending Yola Sub-basin. The Bima Formation is the oldest lithogenetic unit occupying the base of the Cretaceous successions in the Northern Benue Trough. It is differentiated into three members; the Lower Bima (B1), the Middle Bima (B2) and the Upper Bima (B3). Facies and their stratigraphical distribution analyses were conducted on the Lower Bima Member exposed mainly at the core of the NE-SW axially trending Lamurde Anticline in the Yola Sub-basin, with an objective to interpret the paleodepositional environments, and to reconstruct the depositional model and the stratigraphical architecture. Ten (10) lithofacies were identified on the basis of lithology, grain size, sedimentary structures and paleocurrent analysis. The facies constitute three (3) major facies associations; the gravelly dominated, the sandy dominated and the fine grain dominated. These facies and facies associations were interpreted and three facies successions were recognized; the alluvial-proximal braided river, the braided river and the lacustrine-marginal lacustrine. The stratigraphic architecture indicates a rifted (?pull-apart) origin as the facies distribution shows a progradational succession from a shallow lacustrine/marginal lacustrine (at the axial part of the basin) to alluvial fan (sediment gravity flow)-proximal braided river (gravel bed braided river) and braided river (channel and overbank) depositional systems. The facies stacking patterns depict sedimentation mainly controlled by allogenic factors of climate and tectonism.

  2. The effect of plate movements in the northern region of South America on tectonics and sedimentation in the Eastern Llanos Basin

    SciTech Connect

    Pena, L.E. )

    1993-02-01

    The geological configuration of the Eastern Llanos pericratonic mega-basin has been directly affected by the overall tectonic regime experienced in the Northern part of South America. Interaction between the Pacific (Cocos), South American and Caribbean Plates generated a regional compressional dextral rotational force expressed as a regional North-South striking structural trend in the southern part of the basin and an east-west striking trend in portion nearest the Caribbean Plate Boundary. Nearly 90% of the strike-slip faults in this northern area show right lateral displacement. The majority of the structures in the East Llanos basin are related to the Late Miocene uplift of the Eastern Andes. Nevertheless we can subdivide the structures into two major groups: pre-Miocene and post-Miocene. By being able to recognize pre-Miocene Cretaceous age structures, much altered by later movements, we can envision remigration of hydrocarbons out of early traps into those created more recently. Plate tectonic events in the north of South America have produced a general regional structure strike directional through time. Sedimentary-tectonic relationships depend upon regional phenomena which, if interpreted correctly, help to sub-divide the mega-basin into genetically related parts. By understanding the mechanism that creates large scale structural features, the geologist is thus provided with an important tool that can aid him in exploring the Eastern Llanos basin.

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

    SciTech Connect

    Robert Jacobi; John Fountain

    2001-02-28

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

  4. Sedimentological and geochronological evidences of anthropogenic impacts on river basins in the Northern Latium coastal area (Italy)

    NASA Astrophysics Data System (ADS)

    Piazzolla, Daniele; Paladini de Mendoza, Francesco; Scanu, Sergio; Marcelli, Marco

    2015-04-01

    In this work we aimed to compare sedimentological and geochronological data from three sediment core samples (MIG50, MRT50, and GRT50) taken in the Northern Latium (Italy) coastal area, at -50 m depth, to data regarding rainfall, river flows and the land use in the three most important hydrographic basins (Mignone, Marta and Fiora) and in the coastal area. Different trends of sediment mass accumulation rate (MAR) are detected in the three cores: a strongly increasing trend was identified in MIG50 and MRT50 cores while GRT50 doesn't show significant variation. Data from the sedimentological analysis of GRT50 core identify a progressive decrease in the sandy component, which declined from about 30% to the current level of 7% over the last 36 years, while MRT50 and MIG50 cores (mainly composed by pelitic fraction > 95%) showed slight variations of textural ratio between silt and clay. According to the general decrease of pluviometric trend observed in Italy, related to teleconnection pattern tendency (NAO), the statistical analysis of rain identified significative decrease only in the Fiora river basin, whereas in the other two locations the decrease was not as significant. Regarding the Fiora river flow, a significative decreasing trend of average flow is detected, while the flood regime remained unaffected over the past 30 years. The analysis of the land use shows that the human activities are increased of 6-10% over the available time steps (1990 - 2006) in Fiora and Mignone river basins, while the Marta river basin has a strong human impact since 1990 highligting more than 80% of artificial soil covering. The largest variation is observed on the Fiora basin (10%) where the antrhopic activities have expanded to an area of about 85 Km2. Moreover, in the last ten years a large beach nourishment in 2004 (570000 m3) and dredging activities in the early second half of 2000s (1000000 m3 moved) were performed in Marina di Tarquinia beach and in front of the Torrevaldaliga

  5. Assessment of undiscovered conventional oil and gas resources, onshore Claiborne Group, United Statespart of the northern Gulf of Mexico Basin

    USGS Publications Warehouse

    Hackley, P.C.; Ewing, T.E.

    2010-01-01

    The middle Eocene Claiborne Group was assessed for undiscovered conventional hydrocarbon resources using established U.S. Geological Survey assessment methodology. This work was conducted as part of a 2007 assessment of Paleogene-Neogene strata of the northern Gulf of Mexico Basin, including the United States onshore and state waters (Dubiel et al., 2007). The assessed area is within the Upper Jurassic-CretaceousTertiary composite total petroleum system, which was defined for the assessment. Source rocks for Claiborne oil accumulations are interpreted to be organic-rich, downdip, shaley facies of the Wilcox Group and the Sparta Sand of the Claiborne Group; gas accumulations may have originated from multiple sources, including the Jurassic Smackover Formation and the Haynesville and Bossier shales, the Cretaceous Eagle Ford and Pearsall (?) formations, and the Paleogene Wilcox Group and Sparta Sand. Hydrocarbon generation in the basin started prior to deposition of Claiborne sediments and is currently ongoing. Primary reservoir sandstones in the Claiborne Group include, from oldest to youngest, the Queen City Sand, Cook Mountain Formation, Sparta Sand, Yegua Formation, and the laterally equivalent Cockfield Formation. A geologic model, supported by spatial analysis of petroleum geology data, including discovered reservoir depths, thicknesses, temperatures, porosities, permeabilities, and pressures, was used to divide the Claiborne Group into seven assessment units (AUs) with three distinctive structural and depositional settings. The three structural and depositional settings are (1) stable shelf, (2) expanded fault zone, and (3) slope and basin floor; the seven AUs are (1) lower Claiborne stable-shelf gas and oil, (2) lower Claiborne expanded fault-zone gas, (3) lower Claiborne slope and basin-floor gas, (4) lower Claiborne Cane River, (5) upper Claiborne stable-shelf gas and oil, (6) upper Claiborne expanded fault-zone gas, and (7) upper Claiborne slope and basin

  6. Pliocene and Quaternary Deposits in the Northern Part of the San Juan Basin in Southwestern Colorado and Northwestern New Mexico

    USGS Publications Warehouse

    Scott, Glenn R.; Moore, David W.

    2007-01-01

    Unconsolidated late Cenozoic deposits in the northern part of the San Juan Basin range in age from late Pliocene to Holocene. Most of the deposits are alluvial gravel composed of resistant quartzite, sandstone, and igneous, metamorphic, and volcanic rocks derived from the uplifted central core of the San Juan Mountains 20-50 miles (32-80 kilometers) north of the basin. Alluvial deposits are most voluminous in the Animas Valley, but deposits of gravel of the same general age are present in the La Plata, Florida, Los Pinos, and Piedra River valleys as well. Alluvial gravel forms tabular deposits, generally about 20 feet (6 meters) thick, that are exposed beneath a sequence of terraces at many levels above the rivers. Gravel layers 360 feet (110 meters) or less above the Animas River are glacial outwash. The gravel layers begin at the south toes of end moraines and extend discontinuously downvalley at least 10-20 miles (16-32 kilometers). Farther south, distinction between outwash and nonglacial alluvium is problematical. Alluvial gravel beneath higher terraces does not grade to end moraines. Glacial till forms a series of end moraines at the north edge of the town of Durango. The oldest moraines are farthest downvalley, are higher above the river, and have more mature surficial soils than do moraines farther north. The two youngest moraines, the Animas City moraines, are interpreted to be Pinedale in age. They have narrow, ridgelike crests and form nearly unbroken arcs across the valley floor. Small segments of still more weathered moraines, the Spring Creek moraines, are 170-230 feet (52-70 meters) above the river and are 660-990 feet (200-300 meters) farther downvalley. The oldest moraines, the Durango moraines, are on the north end of the unnamed mesa on which Fort Lewis College is located. The base is about 180 feet (55 meters) above the river. These oldest moraines may be of Bull Lake age. Alluvial fans, pediment gravel, and landslides are scattered at several

  7. Occurrence, behavior and distribution of high levels of uranium in shallow groundwater at Datong basin, northern China.

    PubMed

    Wu, Ya; Wang, Yanxin; Xie, Xianjun

    2014-02-15

    Geochemical investigations of uranium (U) occurrence in the environments were conducted at Datong basin of northern China. The results suggest that U contents were generally <1mg/kg for the igneous and metamorphic rocks, typically 2-5mg/kg for the Carboniferous and Permian sedimentary rocks and around 3mg/kg for sediments and topsoil, respectively. U in the Quaternary aquifer sediments may be primarily associated with carnotite from the Carboniferous and Permian coal-bearing clastic rocks around the basin. Shallow groundwater had U concentrations of <0.02-288 μg/L (average 24 μg/L), with 24% of the investigated boreholes above the WHO provisional guideline of 30 μg/L for U in drinking water. Average U concentration for surface water was 5.8 μg/L. In oxidizing waters, uranyl (UO2(2+)) species is dominant and strongly adsorbed onto iron (hydro)xides, while it would be preferentially complexed with carbonate in the alkaline groundwater, forming highly soluble uranyl-carbonate complexes at Datong. Under reducing conditions, uranous (U(IV)) species is ready to precipitate or bind to organic matter, therefore having a low mobility. At the study area, high U groundwater (>30 μg/L) occurs at the alluvial plains due to intermediate redox and enhanced alkaline conditions. The abnormally high levels of U in groundwater (>100 μg/L) are locally found at the west alluvial plains. By contrast, U co-precipitation with secondary carbonate minerals like Ca2UO2(CO3)3 in the dominant Ca-Mg-Na-HCO3 type groundwater may prevail at the east alluvial plains. Besides, bedrocks such as Carboniferous and Permian sedimentary rocks, especially the coal-bearing strata which have higher U contents at the west mountain areas may also account for the abnormally high levels of U in groundwater.

  8. The importance of diverse data types to calibrate a watershed model of the Trout Lake Basin, Northern Wisconsin, USA

    USGS Publications Warehouse

    Hunt, R.J.; Feinstein, D.T.; Pint, C.D.; Anderson, M.P.

    2006-01-01

    As part of the USGS Water, Energy, and Biogeochemical Budgets project and the NSF Long-Term Ecological Research work, a parameter estimation code was used to calibrate a deterministic groundwater flow model of the Trout Lake Basin in northern Wisconsin. Observations included traditional calibration targets (head, lake stage, and baseflow observations) as well as unconventional targets such as groundwater flows to and from lakes, depth of a lake water plume, and time of travel. The unconventional data types were important for parameter estimation convergence and allowed the development of a more detailed parameterization capable of resolving model objectives with well-constrained parameter values. Independent estimates of groundwater inflow to lakes were most important for constraining lakebed leakance and the depth of the lake water plume was important for determining hydraulic conductivity and conceptual aquifer layering. The most important target overall, however, was a conventional regional baseflow target that led to correct distribution of flow between sub-basins and the regional system during model calibration. The use of an automated parameter estimation code: (1) facilitated the calibration process by providing a quantitative assessment of the model's ability to match disparate observed data types; and (2) allowed assessment of the influence of observed targets on the calibration process. The model calibration required the use of a 'universal' parameter estimation code in order to include all types of observations in the objective function. The methods described in this paper help address issues of watershed complexity and non-uniqueness common to deterministic watershed models. ?? 2005 Elsevier B.V. All rights reserved.

  9. Late Cretaceous and Early Tertiary depositional environments of the northern Sacramento basin revealed by seismic-stratigraphic analysis

    SciTech Connect

    Damuth, J.E.; Link, M.H.; Gabay, S.H. )

    1990-05-01

    Seismic-stratigraphic analysis of regional seismic data across the Willows-Beehive Bend gas field reveals a prograding shelf-slope depositional sequence, including basic submarine-fan, slope, and shelf deltaic deposits, that progressively infilled the northern Sacramento forearc basin during the Campanian. The base of the Forbes Formation and the base of the Princeton Gorge fill form the lower and upper boundaries, respectively, of this sequence. Upper Cretaceous submarine-fan and basin-plain deposit form the strata between the Sierran basement and the base of the Forbes and progressively onlap the basement from west to east. The lower to middle Forbes Formation is characterized by high-amplitude discontinuous reflections and consists of mud-rich submarine-fan deposit with laterally restricted, sand-prone channel/levee complexes and broader depositional lobes. In contrast the upper Forbes consist of mud-rich slope deposits characterized by broad, southward-dipping clinoforms. Submarine-canyon/gully fills are common and return discordant hummocky to chaotic reflections. The overlying Kione Formation consists of sand-rich, delta-front deposits that return high amplitude, gently dipping subparallel reflections and are transitional into the slope deposits of the uppermost Forbes. The Kione was partially eroded during cutting of the Princeton Gorge submarine canyon in the early Tertiary. The lower (Eocene) Princeton Gorge fill shows highly variable reflection character and seismic facies that suggest multiple episodes of submarine erosion and deposition. At least three northwest-southeast-striking fault zones, including the Willows fault, disrupt these formations and appear to have strike-slip components.

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

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

    At the Qarhan Salt Lake (QSL) on the central-eastern Qaidam Basin, northern Tibetan Plateau, Quaternary lacustrine sediments have a thickness of over 3000 m and mainly composed of organic-rich clay and silty clay with some silt halite and halite. In this study, a 102-m-long sediment core (ISL1A) was obtained from the QSL. Combining with AMS 14C and 230Th dating, clay minerals and major-element concentrations of ISL1A were used to reconstruct the weathering process and trend of the QSL since late Pleistocene. The results reveal that the clay mineral from <2 μm fraction in ISL1A is composed of illite (47-77%), chlorite (8-27%), smectite (including illite-smectite mixed layers, 3-29%) and kaolinite (2-11%). Such clay mineral assemblages in ISL1A derived primarily from felsic igneous rocks, gneisses and schists of Eastern Kunlun Mountains on the south of the QSL. The abundance of illite mineral displays an opposite fluctuation trending with that of smectite, chlorite and kaolinite mineral in ISL1A, which is significantly different from the monsoon-controlled regions. Moreover, higher values of illite, kaolinite/chlorite and illite/chlorite ratios, and lower values of smectite, chlorite and kaolinite minerals occurred in 83-72.5 ka, 68.8-54 ka, 32-24 ka, corresponding to late MIS 5, late MIS 4, early MIS 3 and late MIS 3, respectively. These three phases were almost similarly changed with oxygen isotopes of authigenic carbonates and pollen records in ISL1A, which implies that stronger chemical weathering corresponds to higher effective moisture periods of source region in the Qaidam Basin. Based on chemical weathering index and (Al2O3-(CaO + Na2O)-K2O) diagram, chemical weathering degree in this study area takes a varying process from low to intermediate on the whole.

  11. Organic geochemical characterisation of shallow marine Cretaceous formations from Yola Sub-basin, Northern Benue Trough, NE Nigeria

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

    The shallow marine shales of the Cretaceous formations namely Yolde, Dukul, Jessu, Sekuliye and Numanha ranging in age from Cenomanian to Coniacian within the Yola Sub-basin in the Northern Benue Trough, northeastern Nigeria were analysed to provide an overview on their hydrocarbon generation potential. This study is based on pyrolysis analysis, total organic carbon content (TOC), extractable organic matter (EOM), biomarker distributions and measured vitrinite reflectance. The present-day TOC contents range between 0.24 and 0.71 wt. % and Hydrogen Index (HI) values between 8.7 and 113 mg HC/g TOC with Type III/IV kerogens. Based on the present-day kerogen typing, the shale sediments are expected to generate mainly gas. Biomarker compositions indicates deposition in a marine environment under suboxic conditions with prevalent contribution of aquatic organic matter and a significant amount of terrigenous organic matter input. Organic matter that is dominated by marine components contains kerogens of Type II and Type II-III. This study shows that the organic matter has been affected by volcanic intrusion and consequently, have reached post-mature stage of oil generation. These higher thermal maturities levels are consistent with the vitrinite reflectance ranging from 0.85 to 2.35 Ro % and high Tmax (440-508 °C) values as supported by biomarker maturity ratios. Based on this study, a high prospect for major gas and minor oil generation potential is anticipated from the shallow marine Cretaceous formations from Yola Sub-basin.

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

    PubMed Central

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

    2015-01-01

    Abstract Two new species of Pseudancistrus, a genus diagnosed by non-evertible cheek plates and hypertrophied odontodes along the snout margin, are described from two drainages of the Brazilian Shield: Pseudancistrus kayabi from the rio Teles Pires (rio Tapajós basin) and Pseudancistrus asurini from the rio Xingu. The new species are distinguished from congeners (Pseudancistrus barbatus, Pseudancistrus corantijniensis, Pseudancistrus depressus, Pseudancistrus nigrescens, Pseudancistrus reus, and Pseudancistrus zawadzkii) by the coloration pattern. Pseudancistrus kayabi has dark bars on the dorsal and caudal fins which are similar to that of Pseudancistrus reus from the Caroní River, Venezuela. Pseudancistrus asurini is unique among Pseudancistrus in having whitish tips of the dorsal and caudal fins in juveniles to medium-sized adults. PMID:25709528

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

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

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

  14. Adaptive transitions and environmental change in the northern Great Basin: A view from Diamond Swamp

    SciTech Connect

    Musil, R.R.

    1992-01-01

    The presence of sedentary prehistoric occupations in association with wetland settings in the Great Basin has been the focus of continued debate. Theoretical discussions concerning the nature of hunter-gatherer adaptations to wetland environments have been based on two models: (1) Stress-based or push models, which argue that hunter-gatherer populations would reduce mobility as a response to less favorable conditions, and (2) abundance-based or pull models, which argue that hunter-gatherers would have been attracted to localized environments of diverse and plentiful resources. Archaeological evidence from Diamond Swamp provides insight into human adaptive transitions in wetland environments. Archaeological data from Diamond Swamp revealed a series of cultural components representing significant portions of the Holocene. The components at the Dunn and McCoy Creek sites consist of collections of artifactual, faunal, and floral materials, in association with semi-subterranean pithouse features dated between 3500 and 900 BP. These occupations correspond to periods of increased moisture and higher water tables. During periods of climatic amelioration semi-sedentary occupations occurred with the expansion of highly productive marsh and juniper grassland vegetation zones. The component at the McCoy Creek Site corresponds to a period of decreasing moisture punctuated by periodic drought, evidenced by the presence of a less substantial wickiup occupation dated at 500 BP. This occupation is indicative of a transition to a more mobile, less intensive occupational episode. The study provides evidence that transitions to sedentary pithouse villages in Diamond Swamp are best accounted for by the abundance-based model. A shift towards a less substantial, more mobile, occupation occurred with a decline in effective moisture. The research reflects adaptations made by local hunter-gatherer populations to long term environmental change within a typical Great Basin wetlands setting.

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

    NASA Astrophysics Data System (ADS)

    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.

  16. Temporal and spatial constraints on the evolution of a Rio Grande rift sub-basin, Guadalupe Mountain area, northern New Mexico

    NASA Astrophysics Data System (ADS)

    Thompson, R. A.; Turner, K. J.; Cosca, M. A.; Drenth, B.; Hudson, M. R.; Lee, J.

    2013-12-01

    The Taos Plateau volcanic field (TPVF) in the southern San Luis Valley of northern New Mexico is the most voluminous of the predominantly basaltic Neogene (6-1 Ma) volcanic fields of the Rio Grande rift. Volcanic deposits of the TPVF are intercalated with alluvial deposits of the Santa Fe Group and compose the N-S-trending San Luis Basin, the largest basin of the northern rift (13,500 km2 in area). Pliocene volcanic rocks of the Guadalupe Mountain area of northern New Mexico are underlain by the southern end of one of the larger sub-basins of the San Luis Valley, the Sunshine sub-basin (~ 450 km2 in area) juxtaposed against the down-to-west frontal fault of the Precambrian-cored Sangre de Cristo Range. The sub-basin plunges northward and extends to near the Colorado-New Mexico border. The western margin (~15 km west of the Sangre de Cristo fault) is constrained by outcrops of Oligocene to Miocene volcanic rocks of the Latir volcanic field, interpreted here as a broad pre-Pliocene intra-rift platform underlying much of the northern TPVF. The southern sub-basin border is derived, in part, from modeling of gravity and aeromagnetic data and is interpreted as a subsurface extension of this intra-rift platform that extends southeastward to nearly the Sangre de Cristo range front. Broadly coincident with this subsurface basement high is the northwest-trending, curvilinear terminus of the down-to-northeast Red River fault zone. South of the gravity high, basin-fill alluvium and ~3.84 Ma Servilleta basalt lava flows thicken along a poorly exposed, down-to-south, basin-bounding fault of the northern Taos graben, the largest of the San Luis Valley sub-basins. The uppermost, western sub-basin fill is exposed along steep canyon walls near the confluence of the Rio Grande and the Red River. Unconformity-bound, lava flow packages are intercalated with paleo Red River fan alluvium and define six eruptive sequences in the Guadalupe Mountain area: (1) Guadalupe Mtn. lavas (dacite ~5

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

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

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

  18. Early-stage rifting of the northern Tyrrhenian Sea Basin: Results from a combined wide-angle and multichannel seismic study

    NASA Astrophysics Data System (ADS)

    Moeller, S.; Grevemeyer, I.; Ranero, C. R.; Berndt, C.; Klaeschen, D.; Sallares, V.; Zitellini, N.; Franco, R.

    2013-08-01

    Extension of the continental lithosphere leads to the formation of rift basins and ultimately may create passive continental margins. The mechanisms that operate during the early stage of crustal extension are still intensely debated. We present the results from coincident multichannel seismic and wide-angle seismic profiles that transect across the northern Tyrrhenian Sea Basin. The profiles cross the Corsica Basin (France) to the Latium Margin (Italy) where the early-rift stage of the basin is well preserved. We found two domains, each with a distinct tectonic style, heat flow and crustal thickness. One domain is the Corsica Basin in the west that formed before the main rift phase of the northern Tyrrhenian Sea opening (˜8-4 Ma). The second domain is rifted continental crust characterized by tilted blocks and half-graben structures in the central region and at the Latium Margin. These two domains are separated by a deep (˜10 km) sedimentary complex of the eastern portion of the Corsica Basin. Travel-time tomography of wide-angle seismic data reveals the crustal architecture and a subhorizontal 15-17 ± 1 km deep Moho discontinuity under the basin. To estimate the amount of horizontal extension we have identified the pre-, syn-, and post-tectonic sedimentary units and calculated the relative displacement of faults. We found that major faults initiated at angles of 45°-50° and that the rifted domain is horizontally stretched by a factor of β ˜ 1.3 (˜8-10 mm/a). The crust has been thinned from ˜24 to ˜17 km indicating a similar amount of extension (˜30%). The transect represents one of the best imaged early rifts and implies that the formation of crustal-scale detachments, or long-lived low-angle normal faults, is not a general feature that controls the rift initiation of continental crust. Other young rift basins, like the Gulf of Corinth, the Suez Rift or Lake Baikal, display features resembling the northern Tyrrhenian Basin, suggesting that half

  19. The 2001 - Present Triggered Seismicity Sequence in the Raton Basin of Southern Colorado/Northern New Mexico

    NASA Astrophysics Data System (ADS)

    Rubinstein, J. L.; Ellsworth, W. L.; McGarr, A.

    2012-12-01

    The occurrence of an earthquake of magnitude (M) 5.3 near Trinidad, CO, on 23 August 2011 renewed interest in the possibility that an earthquake sequence in this region that began in August 2001 is the result of industrial activities. Our investigation of this seismicity, in the Raton Basin of northern New Mexico and southern Colorado, led us to conclude that the majority, if not all of the earthquakes since August 2001 have been triggered by the deep injection of wastewater related to the production of natural gas from the coal-bed methane field here. The evidence that this earthquake sequence was triggered by wastewater injection is threefold. First, there was a marked increase in seismicity shortly after major fluid injection began in the Raton Basin. From 1970 through July of 2001, there were five earthquakes of magnitude 3 and larger located in the Raton Basin. In the subsequent 10 years from August of 2001 through the end of 2011, there were 95 earthquakes of magnitude 3 and larger. The statistical likelihood of this rate increase occurring naturally was determined to be 0.01%. Second, the vast majority of the seismicity is located close (within 5km) to active disposal wells in this region. Additionally, this seismicity is primarily shallow, ranging in depth between 2 and 8 km, with the shallowest seismicity occurring within 500 m depth of the injection intervals. Finally, these wells have injected exceptionally high volumes of wastewater. The 23 August 2011 M5.3 earthquake, located adjacent to two high-volume disposal wells, is the largest earthquake to date for which there is compelling evidence of triggering by fluid injection activities; indeed, these two nearly-co-located wells injected about 4.9 million cubic meters of wastewater during the period leading up to the M5.3 earthquake, more than 7 times as much as the disposal well at the Rocky Mountain Arsenal that caused damaging earthquakes in the Denver, CO, region in the 1960s. Much of the seismicity

  20. Morphology, sedimentary features and evolution of a large palaeo submarine canyon in Qiongdongnan basin, Northern South China Sea

    NASA Astrophysics Data System (ADS)

    Li, Xiangquan; Fairweather, Luke; Wu, Shiguo; Ren, Jianye; Zhang, Hongjie; Quan, Xiayun; Jiang, Tao; Zhang, Cheng; Su, Ming; He, Yunlong; Wang, Dawei

    2013-01-01

    The large Miocene-aged palaeo canyon that extents through the Qiongdongnan basin (QDNB) and Yinggehai basin (YGHB) of Northern South China Sea has been of considerable interest both economically and scientifically over the past decade. Stemmed from this, significant research has been employed into understanding the mechanism for its existence, incision, and sedimentary fill, yet debate remains. In the first case the canyon itself is actually quite anomalous. Alone from the size (over 570 km in length and more than 8 km in width (Yuan et al., 2009)), which is considerably more than most ancient deep-water channels (REFS), the canyon's sedimentary fill is also distinctly different. Some explanations have been given to explain the canyon's origin and existence, these include increased sediment supply from the Red River which is genetically linked to uplift of the Tibetan Plateau, lowstand turbidite and mass-transport activity, reactivation and dextral displacement of the Red River Fault zone inducing erosive gravity-flows, regional tilt of the QDNB and YGHB, paleo-seafloor morphology and seal-level fluctuations. With the application of new data obtained from interpretations of a large number of 2D seismic profiles, core and well log data, and tectonic and sedimentary analysis this contribution aims to: (1) Present models to explain the Canyon's sedimentary fill and basin plain deposits, which provided significant understanding of processes pre-, syn- and post-incision and; (2) review the plausibility and likelihood of each of the controlling mechanisms, hoping to shed light on this controversial aspect. We conclude that the final erosive event that shaped the canyon is dated at 5.5 Ma. The Canyon's unusual fill is a product of variation in the interaction between turbidity currents and MTD that blocked the canyon's axis, and the reduction in gravity flow energy through time; and therefore the complete succession represents one major erosive and cut event at 5.5 Ma and

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

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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

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

    PubMed

    Ahmad, Zulfiqar; Hafeez, Mohsin; Ahmad, Iftikhar

    2012-09-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  4. A water-resources data-network evaluation for Monterey County, California; Phase 3, Northern Salinas River drainage basin

    USGS Publications Warehouse

    Templin, W.E.; Schluter, R.C.

    1990-01-01

    This report evaluates existing data collection networks and possible additional data collection to monitor quantity and quality of precipitation, surface water, and groundwater in the northern Salinas River drainage basin, California. Of the 34 precipitation stations identified, 20 were active and are concentrated in the northwestern part of the study area. No precipitation quality networks were identified, but possible data collection efforts include monitoring for acid rain and pesticides. Six of ten stream-gaging stations are active. Two surface water quality sites are sampled for suspended sediment, specific conductance, and chloride; one U.S. Geological Survey NASOAN site and one site operated by California Department of Water Resources make up the four active sampling locations; reactivation of 45 inactive surface water quality sites might help to achieve objectives described in the report. Three local networks measure water levels in 318 wells monthly, during peak irrigation, and at the end of the irrigation season. Water quality conditions are monitored in 379 wells; samples are collected in summer to monitor saltwater intrusion near Castroville and are also collected annually throughout the study area for analysis of chloride, specific conductance, and nitrate. An ideal baseline network would be an evenly spaced grid of index wells with a density of one per section. When baseline conditions are established, representative wells within the network could be monitored periodically according to specific data needs. (USGS)

  5. Mammalian community response to the latest Paleocene thermal maximum: An isotaphonomic study in the northern Bighorn Basin, Wyoming

    NASA Astrophysics Data System (ADS)

    Clyde, William C.; Gingerich, Philip D.

    1998-11-01

    New stratigraphic and paleontological information from the McCullough Peaks, northern Bighorn Basin, Wyoming, is incorporated into an isotaphonomic faunal database and used to investigate the impact of the latest Paleocene thermal maximum and coincident earliest Wasatchian immigration event on local mammalian community structure. Surface collections from Willwood Formation overbank deposits provide taphonomically consistent and stratigraphically resolved samples of the medium- to large-sized components of underlying mammalian communities. Rarefaction shows that the immigration event caused an abrupt and dramatic increase in species richness and evenness. After this initial increase, diversity tapered off to more typical Wasatchian levels that were still higher than those in the preceding Clarkforkian. Wasatchian immigrants were rapidly incorporated into the new community organization, representing ˜20% of the taxa and ˜50% of the individuals. Immigrant taxa generally had larger body sizes and more herbivorous and frugivorous dietary habits compared to endemic taxa, causing significant turnover in body-size structure and trophic structure. There was a significant short-term body-size decrease in many lineages that may have been prompted by the elevated temperatures and/or decreased latitudinal thermal gradients during the latest Paleocene thermal maximum. Rapid short-term climatic change (transient climates) and associated biotic dispersal can have abrupt and long-lasting effects on mammalian community evolution.

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

    NASA Astrophysics Data System (ADS)

    Zeggane, Houari; Boutoutaou, Djamel

    2016-07-01

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

  7. GIS-based RUSLE modelling of Leça River Basin, Northern Portugal, in two different grid scales

    NASA Astrophysics Data System (ADS)

    Petan, S.; Barbosa, J. L. P.; Mikoš, M.; Pinto, F. T.

    2009-04-01

    Soil erosion is the mechanical degradation caused by the natural forces and it is also influenced by human activities. The biggest threats are the related loss of fertile soil for food production and disturbances of aquatic ecosystems which could unbalance the environment in a wider range. Thus, precise predictions of the soil erosion processes are of a major importance for preventing any kind of environmental degradations. Spatial GIS modelling and erosion maps greatly support the policymaking for land planning and environmental management. Leça River Basin, with a surface of 187 km2, is located in the Northern part of Portugal and it was chosen for testing RUSLE methodology for soil loss prediction and identifying areas with high potential erosion. The model involves daily rainfall data for rainfall erosivity estimation, topographic data for slope length and steepness factor calculation, soil type data, CORINE land cover and land use data. The raster layer model was structured in two different scales: with a grid cell size of 10 and 30 meters. The similarities and differences between the model results of both scales were evaluated.

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

    PubMed

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

    2015-12-30

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

  9. Impact of reclaimed water in the watercourse of Huai River on groundwater from Chaobai River basin, Northern China

    NASA Astrophysics Data System (ADS)

    Yu, Yilei; Song, Xianfang; Zhang, Yinghua; Zheng, Fandong; Liu, Licai

    2016-12-01

    Reclaimed water is efficient for replenishing the dry rivers in northern China, but regional groundwater may be at risk from pollution. Therefore, samples of reclaimed water, river water, and groundwater were collected at the Huai River in the Chaobai River basin in 2010. The water chemistry and isotopic compositions of the samples were analyzed in the laboratory. The reclaimed water had stable compositions of water chemistry and isotopes, and the Na·Ca-HCO3·Cl water type. The water chemistry of the river water was consistent with that of the reclaimed water. A June peak of total nitrogen was the prominent characteristic in the shallow groundwater, which also had the Na·Ca-HCO3·Cl water type. However, the water chemistry and isotopes in most of the deep groundwater remained stable, and the water type was Ca·Mg-HCO3. The amount of reclaimed water recharging the groundwater was about 2.5 × 107 m3/yr. All of the shallow groundwater was impacted by the reclaimed water, with the mixing proportion of reclaimed water ranging from 42% to 80 % in the dry season and from 20% to 86% in the wet season. Only one deep well, with proportions of 67% (dry season) and 28% (wet season), was impacted. TDS, EC, and major ions (Na, K, Cl, NH4-N, NO2-N, and NO3-N) were increased in the impacted wells.

  10. [Monitoring of soil salinization in Northern Tarim Basin, Xinjiang of China in dry and wet seasons based on remote sensing].

    PubMed

    Yao, Yuan; Ding, Jian-Li; Zhang, Fang; Wang, Gang; Jiang, Hong-Nan

    2013-11-01

    Soil salinization is one of the most important eco-environment problems in arid area, which can not only induce land degradation, inhibit vegetation growth, but also impede regional agricultural production. To accurately and quickly obtain the information of regional saline soils by using remote sensing data is critical to monitor soil salinization and prevent its further development. Taking the Weigan-Kuqa River Delta Oasis in the northern Tarim River Basin of Xinjiang as test object, and based on the remote sensing data from Landsat-TM images of April 15, 2011 and September 22, 2011, in combining with the measured data from field survey, this paper extracted the characteristic variables modified normalized difference water index (MNDWI), normalized difference vegetation index (NDVI), and the third principal component from K-L transformation (K-L-3). The decision tree method was adopted to establish the extraction models of soil salinization in the two key seasons (dry and wet seasons) of the study area, and the classification maps of soil salinization in the two seasons were drawn. The results showed that the decision tree method had a higher discrimination precision, being 87.2% in dry season and 85.3% in wet season, which was able to be used for effectively monitoring the dynamics of soil salinization and its spatial distribution, and to provide scientific basis for the comprehensive management of saline soils in arid area and the rational utilization of oasis land resources.

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  12. Facies analysis and petroleum potential of Smackover Formation, western and northern areas, East Texas basin

    SciTech Connect

    Hancharik, J.M.

    1983-03-01

    The Smackover Formation (Upper Jurassic) in northeast Texas is a transgressive-regressive carbonate sequence which has been extensively dolomitized. The Smackover Formation is subdivided informally into a lower and upper member based on distinctive lithologic characteristics. The lower member, which rests conformably on the fluvial-deltaic sandstones of the Upper Jurassic Norphlet Formation, contains a laminated, organic carbonate mudstone facies that grades into an overlying locally fossiliferous, pelletalmicritic facies. The upper member of the Smackover Formation consists mainly of broken skeletal debris and pelletal allochems in a micritic matrix. The sediments are better winnowed and better sorted upward in the sequence. Interbedded with and overlying the skeletal-pelletal facies is a clean well-sorted dolomitized oolitic-grainstone facies. This upper-most informal member marks the beginning of a progradational sequence which lasts throughout the remainder of Smackover deposition and continues through deposition of the evaporities and red beds of the overlying Buckner Formation. Most of the Smackover production in northeast Texas occurs along the Mexia-Talco fault zone in the deeper gentle salt-related anticlines and salt-graben systems. Reservoir rocks are primarily leached and dolomitized oolitic grainstones and dolomite. Laminated organic carbonate mudstones which characterize the lower, transgressive phase of the Smackover Formation provide an excellent source rock for petroleum. Exploration targets for the Smackover Formation are the areas were dolomitized oolitic and skeletal grainstones occur on top of structurally high areas such as over salt ridges or swells in the deeper portions of the basin.

  13. 26Al/10Be burial dating of Xujiayao-Houjiayao site in Nihewan Basin, northern China.

    PubMed

    Tu, Hua; Shen, Guanjun; Li, Haixu; Xie, Fei; Granger, Darryl E

    2015-01-01

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

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

    SciTech Connect

    Robert Jacobi

    2005-05-31

    The primary goal was to enter Phase 2 by analyzing geophysical logs and sidewall cores from a verification well drilled into the Trenton/Black River section along lineaments. However, the well has not yet been drilled; Phase 2 has therefore not been accomplished. We have switched oil and gas exploration and production companies, and are now in continued negotiations with Fortuna concerning a plan to retrieve 18 m of horizontal core across a gas-charged zone in the Trenton/Black River in central New York State, the ''hottest'' play in the Appalachian Basin. We completed analysis of remote sensing images to determine, by using the weights-of-evidence method, which images and processing techniques result in lineaments that best reflect the fractures found in outcrop. The conclusions do not differ from the preliminary conclusions reported in the previous progress report. These data continue to demonstrate that integration of aeromagnetic and remote sensing lineaments, surface structure, and soil gas and seismic allows us to extrapolate Trenton-Black River trends away from confirmatory seismic lines.

  15. Technological improvements in the field-based monitoring of glaciers in the Huasco basin, Northern Chile

    NASA Astrophysics Data System (ADS)

    Cisternas, Sebastián; Uribe, José; Carrión, Daniela; Rivera, Andrés; Corripio, Javier

    2014-05-01

    Difficulties with the terrain, weather conditions and accessibility makes high altitude field-based glacier monitoring (>4000 m.a.s.l) particularly challenging. Due to this field measurements are often incomplete and temporally limited when available. Given the importance of temporal analyses when monitoring glacierised environments (especially those that are directly influenced by human activities such as mining) the development and improvement of field-based monitoring techniques is thus essential. Here a series of field technologies are presented that are intended to improve the monitoring of glaciers in the Pascua Lama mining project, Northern Chile (29º18'S , 70º03'W). Efforts focus on monitoring changes in the energy balance and the spatial distribution of albedo variation over glacier surfaces. Technological innovations are described in the use of: (1) meteorological networks (automatic weather stations) - improved for better transmission in unfavourable weather conditions through the use of high frequency portions of the electromagnetic spectrum; (2) Non-metric fixed camera systems - improved to allow continuous monitoring of glacier albedo variations by using high frequency transmission over the Industrial, Scientific and Medical (ISM) band and low power servers based on ARM architecture. The implementation of these technologies has so far successfully improved data acquisition were applied and offers a robust alternative to the traditional field-based glacier monitoring methods used previously.

  16. Structural architecture and tectonic evolution of the Maghara inverted basin, Northern Sinai, Egypt

    NASA Astrophysics Data System (ADS)

    Moustafa, Adel R.

    2014-05-01

    Large NE-SW oriented asymmetric inversion anticlines bounded on their southeastern sides by reverse faults affect the exposed Mesozoic and Cenozoic sedimentary rocks of the Maghara area (northern Sinai). Seismic data indicate an earlier Jurassic rifting phase and surface structures indicate Late Cretaceous-Early Tertiary inversion phase. The geometry of the early extensional fault system clearly affected the sense of slip of the inverted faults and the geometry of the inversion anticlines. Rift-parallel fault segments were reactivated by reverse slip whereas rift-oblique fault segments were reactivated as oblique-slip faults or lateral/oblique ramps. New syn-inversion faults include two short conjugate strike-slip sets dissecting the forelimbs of inversion anticlines and the inverted faults as well as a set of transverse normal faults dissecting the backlimbs. Small anticline-syncline fold pairs ornamenting the steep flanks of the inversion anticlines are located at the transfer zones between en echelon segments of the inverted faults.

  17. The Manciano Sandstone: a shoreface deposit of Miocene basins of the Northern Apennines, Italy

    NASA Astrophysics Data System (ADS)

    Martini, I. P.; Cascella, A.; Rau, A.

    1995-09-01

    Well exposed, diamond-line cut, quarry-exposures of the Manciano Sandstone allow a detailed analysis of sandy, fossiliferous, nearshore deposits of the shelf of the Northern Apennines. The Manciano Sandstone is characterized by medium to very coarse, washed, fairly well sorted, lithic sandstone, with thin interlayers of sandy conglomerates. It displays two principal, rhythmically alternating sandy facies: (a) slightly burrowed (mostly Macaronichnus, Ophiomorpha, Skolithos) units, trough cross-bedded, locally showing possible tidal bundles with few whole Scutella (echinoid) shells reworked on foresets, or occasional large-scale (approximately 2 m) planar cross-bedded, bar-accretion units; and (b) slightly finer, darker-coloured reddish-brown sandstone units, heavily bioturbated ( Cruziana-Skolithos) ichnofauna) representing slightly more sheltered settings. Large oysters are present in near-living position in a few thin layers and, more commonly, as reworked, comminuted fragments in sandy layers. Many calcareous pebbles and oyster fragments are bored. Other fossils consist of echinoids ( Scutella), some balanids and reworked foraminifera and bryozoa. The Manciano sands were deposited primarily in a wave-dominated shoreface, containing migrating bars/ridges and affected by wave-induced, possibly tidal-enhanced currents. This tidal influence confirms the opening of the Miocene Apenninic Sea to oceans, both the developing Atlantic Ocean to the west and, through a long, narrow seaway, the Asian portion of the Tethys Sea to the east.

  18. Small valley glaciers and the effectiveness of the glacial buzzsaw in the northern Basin and Range, USA

    NASA Astrophysics Data System (ADS)

    Foster, David; Brocklehurst, Simon H.; Gawthorpe, Rob L.

    2008-12-01

    The glacial buzzsaw hypothesis suggests that efficient erosion limits topographic elevations in extensively glaciated orogens. Studies to date have largely focussed on regions where large glaciers (tens of kilometres long) have been active. In light of recent studies emphasising the importance of lateral glacial erosion in lowering peaks and ridgelines, we examine the effectiveness of small glaciers in limiting topography under both relatively slow and rapid rock uplift conditions. Four ranges in the northern Basin and Range, Idaho, Montana, and Wyoming, USA, were chosen for this analysis. Estimates of maximum Pleistocene slip rates along normal faults bounding the Beaverhead-Bitterroot Mountains (~ 0.14 mm y - 1 ), Lemhi Range (~ 0.3 mm y - 1 ) and Lost River Range (~ 0.3 mm y - 1 ) are an order of magnitude lower than those on the Teton Fault (~ 2 mm y - 1 ). We compare the distribution of glacial erosion (estimated from cirque floor elevations and last glacial maximum (LGM) equilibrium line altitude (ELA) reconstructions) and fault slip rate with three metrics of topography in each range: the along-strike maximum elevation swath profile, hypsometry, and slope-elevation profiles. In the slowly uplifting Beaverhead-Bitterroot Mountains, and Lemhi and Lost River Ranges, trends in maximum elevation parallel ELAs, independent of variations in fault slip rate. Maximum elevations are offset ~ 500 m from LGM ELAs in the Lost River Range, Lemhi Range, and northern Beaverhead-Bitterroot Mountains, and by ~ 350 m in the southern Beaverhead-Bitterroot Mountains, where glacial extents were less. The offset between maximum topography and mean Quaternary ELAs, inferred from cirque floor elevations, is ~ 350 m in the Lost River and Lemhi Ranges, and 200-250 m in the Beaverhead-Bitterroot Mountains. Additionally, slope-elevation profiles are flattened and hypsometry profiles show a peak in surface areas close to the ELA in the Lemhi Range and Beaverhead-Bitterroot Mountains

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

    NASA Astrophysics Data System (ADS)

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

    2016-10-01

    There has been a considerable amount of research linking climatic variability to hydrologic responses in the western United States. Although much effort has been spent to assess and predict changes in surface water resources, little has been done to understand how climatic events and changes affect groundwater resources. This study focuses on characterizing and quantifying the effects of large, multiyear, quasi-decadal groundwater recharge events in the northern Utah portion of the Great Basin for the period 1960-2013. Annual groundwater level data were analyzed with climatic data to characterize climatic conditions and frequency of these large recharge events. Using observed water-level changes and multivariate analysis, five large groundwater recharge events were identified with a frequency of about 11-13 years. These events were generally characterized as having above-average annual precipitation and snow water equivalent and below-average seasonal temperatures, especially during the spring (April through June). Existing groundwater flow models for several basins within the study area were used to quantify changes in groundwater storage from these events. Simulated groundwater storage increases per basin from a single recharge event ranged from about 115 to 205 Mm3. Extrapolating these amounts over the entire northern Great Basin indicates that a single large quasi-decadal recharge event could result in billions of cubic meters of groundwater storage. Understanding the role of these large quasi-decadal recharge events in replenishing aquifers and sustaining water supplies is crucial for long-term groundwater management.

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

    USGS Publications Warehouse

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

    2016-01-01

    There has been a considerable amount of research linking climatic variability to hydrologic responses in the western United States. Although much effort has been spent to assess and predict changes in surface water resources, little has been done to understand how climatic events and changes affect groundwater resources. This study focuses on characterizing and quantifying the effects of large, multiyear, quasi-decadal groundwater recharge events in the northern Utah portion of the Great Basin for the period 1960–2013. Annual groundwater level data were analyzed with climatic data to characterize climatic conditions and frequency of these large recharge events. Using observed water-level changes and multivariate analysis, five large groundwater recharge events were identified with a frequency of about 11–13 years. These events were generally characterized as having above-average annual precipitation and snow water equivalent and below-average seasonal temperatures, especially during the spring (April through June). Existing groundwater flow models for several basins within the study area were used to quantify changes in groundwater storage from these events. Simulated groundwater storage increases per basin from a single recharge event ranged from about 115 to 205 Mm3. Extrapolating these amounts over the entire northern Great Basin indicates that a single large quasi-decadal recharge event could result in billions of cubic meters of groundwater storage. Understanding the role of these large quasi-decadal recharge events in replenishing aquifers and sustaining water supplies is crucial for long-term groundwater management.

  1. Lower Permian stems as fluvial paleocurrent indicators of the Parnaíba Basin, northern Brazil

    NASA Astrophysics Data System (ADS)

    Capretz, Robson Louiz; Rohn, Rosemarie

    2013-08-01

    A comprehensive biostratinomic study was carried out with abundant stems from the Lower Permian Motuca Formation of the intracratonic Parnaíba Basin, central-north Brazil. The fossils represent a rare tropical to subtropical paleofloristic record in north Gondwana. Tree ferns dominate the assemblages (mainly Tietea, secondarily Psaronius), followed by gymnosperms, sphenophytes, other ferns and rare lycophytes. They are silica-permineralized, commonly reach 4 m length (exceptionally more than 10 m), lie loosely on the ground or are embedded in the original sandstone or siltstone matrix, and attract particular attention because of their frequent parallel attitudes. Many tree fern stems present the original straight cylindrical to slightly conical forms, other are somewhat flattened, and the gymnosperm stems are usually more irregular. Measurements of stem orientations and dimensions were made in three sites approximately aligned in a W-E direction in a distance of 27.3 km at the conservation unit "Tocantins Fossil Trees Natural Monument". In the eastern site, rose diagrams for 54 stems indicate a relatively narrow azimuthal range to SE. These stems commonly present attached basal bulbous root mantles and thin cylindrical sandstone envelopes, which sometimes hold, almost adjacent to the lateral stem surface, permineralized fern pinnae and other small plant fragments. In the more central site, 82 measured stems are preferentially oriented in the SW-NE direction, the proportion of gymnosperms is higher and cross-stratification sets of sandstones indicate paleocurrents mainly to NE and secondarily to SE. In the western site, most of the 42 measured stems lie in E-W positions. The predominantly sandy succession, where the fossil stems are best represented, evidences a braided fluvial system under semiarid conditions. The low plant diversity, some xeromorphic features and the supposedly almost syndepositional silica impregnation of the plants are coherent with marked dry

  2. Geochemistry and petrogenesis of the Belmont diabase sheet, northern Culpeper Basin, Virginia

    SciTech Connect

    Mihm, K.A.; Nielsen, R.L.

    1985-01-01

    The Belmont diabase sheet (BDS) is one of numerous hypabyssal tholeiitic intrusions common to the early Mesozoic rift valleys of the mid-Atlantic states. Petrographic, microprobe and whole rock major and trace element analyses in conjunction with limited field and geophysical evidence indicate that the BDS is a westward dipping, irregular basin-shaped intrusive sheet of high-TiO/sub 2/ quartz-normative type diabase. The bulk of the exposed portion of the BDS is fractionated relative to the chill zone composition. A semi-circular outcrop pattern of relatively high MgO rocks surrounds the main body of the BDS. These high-MgO rocks share a distinctive petrography characterized by large, anhedral OPX grains often mantled by inverted pigeonite and are interpreted as a basal cumulate zone. Drill core samples collected from the western portion of the sheet penetrate 500' of fractionated diabase without intersecting the high-MgO layer or a lower chill margin, however,subhedral grains of inverted pigeonite appear in the lowermost core samples. This suggests that the cumulate layer underlies the sheet of >500' depth on the W side and crops out up-dip to the E, N and S where the sheet margins are turned upward. Mass balance calculations indicate that the exposed high-MgO rocks may be derived from the chill margin composition by accumulation of 13% OPX + 2% CPX + 5% PLAG (AN52) and the remaining rocks of the BDS are derived through fractional crystallization of varying amounts of CPX, OPX and PLAG. Magmatic features characteristic of similar tholeiitic intrusions such as rhythmic layering and a Mg-olivine layer were not observed. However, examination of the BDS and other hypabyssal intrusions offers insight into the limitations and circumstances under which these features may be developed.

  3. Permeability-porosity relationships of shallow mudstones in the Ursa Basin, northern deepwater Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Reece, Julia Schneider; Flemings, Peter B.; Dugan, Brandon; Long, Hui; Germaine, John T.

    2012-12-01

    In the Ursa Basin, Gulf of Mexico, in situ mudstone permeability near the seafloor declines from 1.1 × 10-16 to 5.8 × 10-19 m2over a depth of 578 m. We can reproduce this in situ permeability-porosity behavior through consolidation experiments in the laboratory. We use uniaxial constant-rate-of-strain consolidation experiments to measure permeability-porosity relationships and derive in situ permeabilities of 31 mudstone samples collected at Integrated Ocean Drilling Program (IODP) Sites U1324 and U1322. Although these mudstones have similar grain-size distributions, permeability at a given porosity varies significantly between the samples due to small variations in composition or fabric. We calculate an upscaled permeability relationship based on the observed permeability variation in the samples and determine a resultant large-scale permeability anisotropy of around 30. Based on this upscaled relationship and observations of in situ pressure, we calculate upward fluid flow rates of 0.5 mm/yr. We find that given the observed compressibility, permeability, and the geologic forcing at Ursa, overpressures are predicted as observed in the subsurface. The primary mechanism for overpressure generation at Ursa is sediment loading due to rapid burial. Low vertical permeabilities, accompanied by high sedimentation rates, can cause severe overpressure near the seafloor, which controls fluid flow and can reduce slope stability as observed in the Mississippi Canyon region. Such flow systems, especially at intermediate depths on passive margins, are important due to their control over macroscale behavior such as topographic gradient of continental slopes and submarine landslides, but have been largely understudied in the past.

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

    PubMed

    Ding, Yuekui; Shan, Baoqing; Zhao, Yu

    2015-09-17

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

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

    PubMed Central

    Ding, Yuekui; Shan, Baoqing; Zhao, Yu

    2015-01-01

    We applied a river habitat quality (RHQ) assessment method to the Hai River Basin (HRB); an important economic centre in China; to obtain baseline information for water quality improvement; river rehabilitation; and watershed management. The results of the assessment showed that the river habitat in the HRB is seriously degraded. Specifically; 42.41% of the sites; accounting for a river length of 3.31 × 104 km; were designated poor and bad. Habitat in the plain areas is seriously deteriorated; and nearly 50% of the sites; accounting for a river length of 1.65 × 104 km; had either poor or bad habitats. River habitat degradation was attributable to the limited width of the riparian zone (≤5 m); lower coverage of riparian vegetation (≤40%); artificial land use patterns (public and industrial land); frequent occurrence of farming on the river banks and high volumes of solid waste (nearly 10 m3); single flow channels; and rare aquatic plants (≤1 category). At the regional scale; intensive artificial land use types caused by urbanization had a significant impact on the RHQ in the HRB. RHQ was significantly and negatively correlated with farmland (r = 1.000; p < 0.01) and urban land (r = 0.998; p < 0.05); and was significantly and positively correlated with grassland and woodland (r = 1.000; p < 0.01). Intensive artificial land use; created through urbanization processes; has led to a loss of the riparian zone and its native vegetation; and has disrupted the lateral connectivity of the rivers. The degradation of the already essentially black rivers is exacerbated by poor longitudinal connectivity (index of connectivity is 2.08–16.56); caused by reservoirs and sluices. For river habitat rehabilitation to be successful; land use patterns need to be changed and reservoirs and sluices will have to be regulated. PMID:26393628

  6. Controls of oil family distribution and composition in nonmarine petroleum systems: A case study from Inner Mongolia Erlian basin, Northern China

    NASA Astrophysics Data System (ADS)

    Chen, Zhelong; Liu, Guangdi; Huang, Zhilong; Lu, Xuejun; Luo, Qiang; Ding, Xiujian

    2014-10-01

    The Erlian basin is a continental rift basin located in Inner Mongolia, Northern China. It is a typical representative of Cretaceous Northeast Asian Rift System, which includes many small petroliferous basins in Mongolia Republic and Northern China. Although Lower Cretaceous source rocks are understood to be most important in the Erlian petroleum systems, the precise identification of these source rock intervals and their determination on oil families distribution and composition are poorly understood in this tectonically complicated, nonmarine basin. New bulk data have been gathered from source rock intervals, oil sands and crude oil samples in eight main oil-producing subbasins. Geochemical analyses indicate that Lower Cretaceous Aershan formation (K1ba) and Tengger 1 formation (K1bt1) are two main source intervals in the Erlian basin and their source rock facies vary from profundal lacustrine to marginal lacustrine according to biomarker and trace elements calibration, the profundal lacustrine facies is characterised by brackish water and anoxic environment, which is similar to their correlative oils (Family 1 oils). The marginal lacustrine facies is characterised by freshwater and suboxic environment, which sourced the most common Family 2 oils. Meanwhile, different maturation processes exercise the second control on oil groups and their compositions, the profundal lacustrine source rocks characterised by their sulphur-rich kerogens lead to two oil groups (group 1 and group 2 oils), whose maturity range from low to normal; while, the marginal lacustrine source rock only lead to normal-maturity oils. At last, biodegradation affected the composition of a certain oils and formed group 4 heavy oils. In addition, short migration distance in small subbasins made the contamination or fractionation less notable in the Erlian basin.

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  8. Preliminary nannofossil and geochemical data from Jurassic black shales from the Qiangtang Basin, northern Tibet

    NASA Astrophysics Data System (ADS)

    Chen, Lan; Jenkyns, Hugh C.; Xu, Guiwen; Mattioli, Emanuela; Da, Xuejuan; Yi, Haisheng; Xia, Minquan; Zhu, Zhangxiong; Huang, Zhaohui

    2016-01-01

    This paper presents new biostratigraphic and geochemical data from the Biluo Co section in northern Tibet, which exposes Jurassic black organic-rich shales, locally containing abundant coccoliths. Because of a general lack of macrofossils, the stratigraphic ages have been a matter of debate. However, coccoliths suggest an Early Bajocian through Bathonian to possibly Early Callovian age (Middle Jurassic) for the middle-upper part of the section. In this study, a range of trace-metal paleoredox proxies is used to assess how seawater oxygen levels varied both locally and globally during the deposition of these shales. The redox-sensitive elements V, Cr, U, Ni, Cu, Mo, Co, Cd and Zn exhibit relatively high concentrations and element/Al ratios. In particular, the Ni compositions fluctuate between ∼75 ppm and ∼106 ppm and Mo between ∼1 ppm and ∼7 ppm: values that are higher than those of the post-Archean Average Shale. Palaeoproductivity proxies, such as Zn, P and Cd, which can be fixed in elevated concentrations in sediments deposited under generally reducing conditions, are also relatively enriched. Furthermore, the U-Mo concentrations and Enrichment Factors (EFs) are consistent with deposition under predominantly suboxic to weakly anoxic conditions. Scattered bivalves, however, point to at least intermittent oxic conditions on the sea floor. Based on the redox-sensitive trace-element concentrations, together with ratios (V/(V + Ni), Ni/Co and V/Cr), the formation of the Biluo Co black shales, in Tibet was probably caused by increased productivity and organic-matter flux, leading to enhanced preservation of organic material under low-oxygen conditions.

  9. Debris flows on Belding Creek, Salmonberry River basin, northern Oregon Coast Range

    SciTech Connect

    Burris, L.M. . Dept. of Geology)

    1993-04-01

    Belding Creek, a tributary of the Salmonberry River, has experienced repeated debris flow episodes. The Salmonberry River flows through Paleocene Tillamook Basalt and is located at longitude 45[degree]43 minutes in the Northern Oregon Coast Range. On January 9, 1990, a debris flow initiated on a first order tributary of Belding Creek during a heavy precipitation event. A month later another debris flow initiated on a different first order stream under similar conditions. Both debris flows traveled for a distance of approximately 2.1 km and poured into the main Belding Creek channel washing out Belding Road which crosses the stream. Numerical data was obtained from the youngest flow deposit. The debris flow material density is 2.5 g/cm[sup 3]. It traveled at an average velocity of 2.9 m/s with a shear strength of 2.5 [times] 10[sup 4] dn/cm[sup 2], a friction angle of 4[degree], and a cohesion value of 1.4 [times] 10[sup 4] dn/cm[sup 3]. Less than 3% of the fine sediments deposited are clay and silt. Deposits from previous, older debris flow events are in and adjacent to the Belding Creek stream channel. Similar processes are evident in other major tributaries of the Salmonberry River, although these other stream channels have not shown recent activity. Each stream in the area that has experienced past debris flows similar to Belding Creek has a landslide feature at the top and follows regional lineation patterns.

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

    SciTech Connect

    Blount, G.; Millings, M.

    2011-08-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2008-12-01

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

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

    SciTech Connect

    Robert Jacobi; John Fountain

    2005-03-01

    The primary goal was to enter Phase 2 by analyzing geophysical logs and sidewall cores from a verification well drilled into the Trenton/Black River section along lineaments. However, the well has not yet been drilled; Phase 2 has therefore not been accomplished. We have switched oil and gas exploration and production companies, and are now, in conjunction with Fortuna, planning to retrieve 18 m of horizontal core across a gas-charged zone in the Trenton/Black River in central New York State, the ''hottest'' play in the Appalachian Basin. Secondary goals in Phase I were also completed in previous reporting period. Although new structural data were collected and analyzed for a few regions where we had no data, the results did not change the previous conclusions. We have also continued analyzing remote sensing images to determine, by using the weights-of-evidence method, which images and processing techniques result in lineaments that best reflect the fractures found in outcrop. We have tested the lineaments from EarthSat (1997), as well as lineaments we identified on Landsat and ASTER images. For fracture intensification domains (FIDs) along Seneca Lake, we found that lineaments identified on a fused image of Landsat and ASTER images produced better correlation to FIDs than lineaments from EarthSat (1997) and ASTER alone. This relationship held true for all orientations of FIDs except E-striking FIDs, which showed a better correlation with lineaments observed on ASTER lineaments than on the fused Landsat and ASTER image lineaments. For Cayuga Lake FIDs, lineaments identified on a fused image of Landsat and ASTER images also produced significantly better correlation to FIDs than lineaments from ASTER alone for NW- and NNW-striking FIDs. However, for NE-, ENE- and E-striking FIDs, ASTER lineaments generally showed the closest match. These data continue to demonstrate that integration of aeromagnetic and remote sensing lineaments, surface structure, soil gas and

  13. Crustal thinning in the northern Tyrrhenian Rift: Insights from multichannel and wide-angle seismic data across the basin

    NASA Astrophysics Data System (ADS)

    Moeller, S.; Grevemeyer, I.; Ranero, C. R.; Berndt, C.; Klaeschen, D.; Sallares, V.; Zitellini, N.; Franco, R.

    2014-03-01

    Extension of the continental lithosphere leads to the formation of rift basins or rifted continental margins if breakup occurs. Seismic investigations have repeatedly shown that conjugate margins have asymmetric tectonic structures and different amount of extension and crustal thinning. Here we compare two coincident wide-angle and multichannel seismic profiles across the northern Tyrrhenian rift system sampling crust that underwent different stages of extension from north to south and from the flanks to the basin center. Tomographic inversion reveals that the crust has thinned homogeneously from ~24 km to ~17 km between the Corsica Margin and the Latium Margin implying a β factor of ~1.3-1.5. On the transect 80 km to the south, the crust thinned from ~24 km beneath Sardinia to a maximum of ~11 km in the eastern region near the Campania Margin (β factor of ~2.2). The increased crustal thinning is accompanied by a zone of reduced velocities in the upper crust that expands progressively toward the southeast. We interpret that the velocity reduction is related to rock fracturing caused by a higher degree of brittle faulting, as observed on multichannel seismic images. Locally, basalt flows are imaged intruding sediment in this zone, and heat flow values locally exceed 100 mW/m2. Velocities within the entire crust range 4.0-6.7 km/s, which are typical for continental rocks and indicate that significant rift-related magmatic underplating may not be present. The characteristics of the pre-tectonic, syn-tectonic and post-tectonic sedimentary units allow us to infer the spatial and temporal evolution of active rifting. In the western part of the southern transect, thick postrift sediments were deposited in half grabens that are bounded by large fault blocks. Fault spacing and block size diminish to the east as crustal thinning increases. Recent tectonic activity is expressed by faults cutting the seafloor in the east, near the mainland of Italy. The two transects show

  14. Lake level and climate records of the last 90 ka from the Northern Basin of Lake Van, eastern Turkey

    NASA Astrophysics Data System (ADS)

    Çağatay, M. N.; Öğretmen, N.; Damcı, E.; Stockhecke, M.; Sancar, Ü.; Eriş, K. K.; Özeren, S.

    2014-11-01

    Sedimentary, geochemical and mineralogical analyses of the ICDP cores recovered from the Northern Basin (NB) of Lake Van provide evidence of lake level and climatic changes related to orbital and North Atlantic climate system over the last 90 ka. High lake levels are generally observed during the interglacial and interstadial periods, which are marked by deposition of varved sediments with high total organic carbon (TOC), total inorganic carbon (TIC), low detrital influx (high Ca/F) and high δ18O and δ13C values of authigenic carbonate. During the glacial and stadial periods of 71-58 ka BP (Marine Isotope Stage 4, MIS4) and end of last glaciation-deglaciation (30-14.5 ka BP; MIS3) relatively low lake levels prevailed, and grey homogeneous to faintly laminated clayey silts were deposited at high sedimentation and low organic productivity rates. Millennial-scale variability of the proxies during 60-30 ka BP (MIS3 is correlated with the Dansgaard-Oeschger (D-O)) and Holocene abrupt climate events in the Atlantic. These events are characterized by laminated sediments, with high TOC, TIC, Ca/Fe, δ18O and δ13C values. The Lake Van NB records correlate well in the region with the climate records from the lakes Zeribar and Urmia in Iran and the Sofular Cave in NW Anatolia, but are in general in anti-phase to those from the Dead Sea Basin (Lake Lisan) in the Levant. The relatively higher δ18O values (0 to -0.4‰) for the interglacial and interstadial periods in the Lake Van NB section are due to the higher temperature and seasonality of precipitation and higher evaporation, whereas the lower values (-0.8 to -2‰) during the glacial and stadial periods are caused mainly by relative decrease in both temperature and seasonality of precipitation. The high δ18O values (up to 4.2‰) during the Younger Dryas, together with the presence of dolomite and low TOC contents, supports evaporative conditions and low lake level. A gradual decrease in the δ18O values from an

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

    USGS Publications Warehouse

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

    2012-01-01

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

  16. Salt Tectonics of Basin and Range Systems in the Sub-Himalayas of Northern Pakistan Using InSAR and 2D Seismic Interpretation

    NASA Astrophysics Data System (ADS)

    Ahmad Abir, I.; Khan, S.; Wulamu, A.; Tariq, S.; Tahir Shah, M.

    2014-12-01

    The western end of the Sub-Himalayas is located in northern Pakistan, where salt tectonics greatly affects its deformation style of geological structures, hydrocarbon exploration and seismology. Three foreland sub-basins are located adjacent to each other in this area: the Potwar Plateau-Salt Range, Kohat Plateau-Surghar Range and the Bannu Basin-Marwat-Khisor Ranges. It is strongly believed that the difference in deformation intensity between these sub-basins is attributed to the presence or absence of a Pre-Cambrian salt layer. This study is an attempt to investigate the extent and role of salt in the geological deformation of northern Pakistan using the Small Baseline Subset Interferograms (SBAS) technique and 2-D seismic interpretations. 10 PALSAR images and 5 seismic profiles from the Potwar Plateau-Salt Range region were used in this study. SBAS results, derived from PALSAR images spanning from 2007 to 2010, suggest that the Potwar Plateau-Salt Range may still be tectonically active with the western portion of the region experiencing an uplift at an average rate of 12 mm/year. Time-migrated seismic profiles were interpreted, showing basement ramps due to normal faults. These ramps are believed to act as transition zones between different roles of salt; the salt layer acts as a decollement in northern Potwar Plateau while salt flow-induced structures are prominent in southern Potwar Plateau. These normal fault ramps are located in the central Salt Range and may be affecting the flow of salt by impeding the flow, which results in the salt being pushed to either side of the ramp. The integration of SBAS and 2D seismic interpretation has led to the suggestion that both the presence of the salt layer and the geometry of the basement influence the deformation style in northern Pakistan.

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

    USGS Publications Warehouse

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

    2007-01-01

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

  18. Delineation of ground-water basins and recharge areas for municipal water-supply springs in a karst aquifer system in the Elizabethtown area, northern Kentucky

    USGS Publications Warehouse

    Taylor, C.J.

    1997-01-01

    Ground-water basins and recharge areas for municipal water-supply springs for the Elizabethtown area, northern Kentucky, were delineated using a hydrogeologic-mapping approach, potentiometric map interpretation, anddye-tracing tests. Five distinct ground-water basins drained by major karst springs are present in the Elizabethtown area. These basins are composed of networks of hydraulically interconnected solution conduits and fractures. The boundaries of the basins for Elizabethtown and Dyers Springs-the primary sources of water for the city of Elizabethtown-weredelineated by the positions of inferred ground-water divides on an existing potentiometric contour map. The results of dye-tracing tests, plotted as straight- line flowpaths, were used to confirm the presence and location of inferred ground-water divides and to adjust the position of the basin boundaries. Recharge areas of 4.8 and 2.7 square miles weredelineated for Elizabethtown and Dyers Springs, respectively. Swallets that drain concentrated stormwater runoff from major highways are presentin the recharge areas for both municipal-supply springs. Each spring is therefore potentially vulnerable to stormwater-runoff contaminants oraccidental spills and releases of toxic or hazardous materials into certain highway drainage culverts.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  20. Optical Properties Of Mineral Dust Particles Mixed With Black Carbon In Indo-Ganges Basin, Northern India

    NASA Astrophysics Data System (ADS)

    Mishra, S. K.; Tripathi, S. N.

    2008-12-01

    non spherical shapes such as concentric spheres, spheroids, ellipsoids and layered rectangular bar, and various combinations of spheres and spheroids attached externally (maximum up to three). References Clarke, A. D., et al. (2004), Size distributions and mixtures of dust and black carbon aerosol in Asian outflow: Physiochemistry and optical properties, J. Geophys. Res., 109, D15S09. Dey, S., et al. (2008), On the mixing state of aerosols in the Indo-Gangetic basin, northern India, Geophys. Res. Lett., 35, L03808. Draine, B. T., and P. J. Flatau (2004), User Guide for the Discrete Dipole Approximation Code DDSCAT 6.1, http://arxiv.org/abs/astro-ph/0409262v2. Lau, K. M., et al. (2006), Asian summer monsoon anomalies induced by aerosol direct forcing: the role of the Tibetan Plateau., J. Climate, 26, 855-864. Mishra, S. K., and S. N. Tripathi (2008), Modeling optical properties of mineral dust over the Indian Desert, J. Geophys. Res., accepted. Sokolik, I. N., and O. B. Toon (1999), Incorporation of mineralogical composition into models of the radiative properties of mineral aerosol from UV to IR wavelengths, J. Geophys. Res., 104, 9423- 9444. Tripathi S. N., et al. (2005), Aerosol black carbon radiative forcing at an industrial city in Northern India, Geophys. Res. Lett., 32(8), L08802. class="ab'>

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

    USGS Publications Warehouse

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

    1985-01-01

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

  2. A multidisciplinary study of the complex Santa Barbara-Furrial oilfields, Northern Monagas area, Eastern Venezuela Basin

    SciTech Connect

    Bojas, B.; Salazar, A.; Robinson, A.; Meunier, M.; Oviedo, P.; Swallow, J.; Diamond, L. )

    1993-02-01

    A multidisciplinary study has been conducted on the giant oilfields located in the northern Monagas area of the eastern Venezuela basin. The oilfields occur in a lower tertiary and Cretaceous sequence which has been heavily tectonized as a consequence of recent transpression along the Caribbean south American plate boundary. This structurally complex area was initially mapped by using 3000 km. Of 2D seismic data. Experience has shown these data to be inadequate and a 150 sq Km 3D survey was acquired over the Santa Barbara area. These data have been interpreted and several new structural features have been identified. As a consequence of this work the structural model has been modified and applied throughout the area. The Cretaceous to late Oligocene sediments, including the Naricual formation which is the main producing horizon, has been studied systematically. These sediments were deposited initially in a fluvial environment which was gradually inundated by successive marine incursions. Approximately 7000 ft of core has been logged and the sedimentary facies and sequence boundaries recognized were then used to calibrate electric logs which allowed facies extrapolation across the whole area. The final parasequence analysis has provided a detailed and reliable reservoir correlation. Original pressure data and subsequent production histories, together with different known oil-water contacts implies separate producing areas. Complex fluid segregations, from condensates to heavy oil had also to be explained. The integration of the geophysical, geological, fluid and production data has allowed each discipline to refine their field models by removing conflicts between these data, thereby producing a better overall description of the reservoir.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  4. Systematic assessment of fault stability in the Northern Niger Delta Basin, Nigeria: Implication for hydrocarbon prospects and increased seismicities

    NASA Astrophysics Data System (ADS)

    Adewole, E. O.; Healy, D.

    2017-03-01

    Accurate information on fault networks, the full stress tensor, and pore fluid pressures are required for quantifying the stability of structure-bound hydrocarbon prospects, carbon dioxide sequestration, and drilling prolific and safe wells, particularly fluid injections wells. Such information also provides essential data for a proper understanding of superinduced seismicities associated with areas of intensive hydrocarbon exploration and solid minerals mining activities. Pressure and stress data constrained from wells and seismic data in the Northern Niger Delta Basin (NNDB), Nigeria, have been analysed in the framework of fault stability indices by varying the maximum horizontal stress direction from 0° to 90°, evaluated at depths of 2 km, 3.5 km and 4 km. We have used fault dips and azimuths interpreted from high resolution 3D seismic data to calculate the predisposition of faults to failures in three faulting regimes (normal, pseudo-strike-slip and pseudo-thrust). The weighty decrease in the fault stability at 3.5 km depth from 1.2 MPa to 0.55 MPa demonstrates a reduction of the fault strength by high magnitude overpressures. Pore fluid pressures > 50 MPa have tendencies to increase the risk of faults to failure in the study area. Statistical analysis of stability indices (SI) indicates faults dipping 50°-60°, 80°-90°, and azimuths ranging 100°-110° are most favourably oriented for failure to take place, and thus likely to favour migrations of fluids given appropriate pressure and stress conditions in the dominant normal faulting regime of the NNDB. A few of the locally assessed stability of faults show varying results across faulting regimes. However, the near similarities of some model-based results in the faulting regimes explain the stability of subsurface structures are greatly influenced by the maximum horizontal stress (SHmax) direction and magnitude of pore fluid pressures.

  5. Yield Responses of Ruderal Plants to Sucrose in Invasive-Dominated Sagebrush Steppe of the Northern Great Basin

    USGS Publications Warehouse

    Brunson, J.L.; Pyke, D.A.; Perakis, S.S.

    2010-01-01

    Restoration of sagebrush-steppe plant communities dominated by the invasive ruderals Bromus tectorum (cheatgrass) and Taeniatherum caput-medusae (medusahead) can be facilitated by adding carbon (C) to the soil, stimulating microbes to immobilize nitrogen (N) and limit inorganic N availability. Our objectives were to determine responses in (1) cheatgrass and medusahead biomass and seed production; (2) soil microbial biomass C and N; and (3) inorganic soil N to a range of C doses and to calculate the lowest dose that yielded a significant response. In November 2005, we applid 12 C doses ranging from 0 to 2,400 kg C/ha as sucrose to plots sown with cheatgrass and medusahead at two sites in the northern Great Basin. Other ruderal plants established in our plots, and this entire ruderal community was negatively affected by C addition. End-of-year biomass of the ruderal community decreased approximately by approximately 6% at each site for an increase in C dose of 100 kg C/ha. For the same increase in C, microbial biomass C increased by 2-4 mg/kg in November 2005 and March 2006, but not in July 2006. There was little, if any, microbial soil N uptake, as microbial biomass N increased by 0.3 mg/kg at only one site at the earliest date, in November 2005. Soil nitrate (NO3-) measured via resin capsules placed in situ for the study duration decreased at both sites with increasing C. Although we found no threshold dose of C, for a significant reduction in ruderal biomass, we calculated lowest significant doses of 240-640 kg C/ha. ?? 2010 Society for Ecological Restoration International.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  7. A longitudinal epidemiological survey of bovine trypanosomosis and its vectors in the White Volta river basin of Northern Ghana.

    PubMed

    Mahama, C I; Desquesnes, M; Dia, M L; Losson, B; De Deken, R; Speybroeck, N; Geerts, S

    2005-03-31

    A longitudinal epidemiological survey of bovine trypanosomosis and its vectors was carried out in the Volta river basin of Northern Ghana to determine the relationship between cattle management and the incidence of bovine trypanosomosis. Two groups of sentinel cattle under different systems of management, classified as "fully-sedentary" and "partially-sedentary" (depending on the type of management) were followed over a 1-year period starting from March 2003 onwards. Cattle were screened at intervals of 3 months using the buffy coat technique (BCT). Buffy coat specimen from animals that were positive for the BCT and those that were negative, but with a packed cell volume (PCV) of less than 21% were further tested using the polymerase chain reaction (PCR). Plasma from all animals were tested for antibody using the indirect antibody enzyme-linked immunosorbent assay (ELISA). Trypanosomosis challenge was determined in tandem with the epidemiological survey with watering sites of sentinel cattle being the foci of interest. The parasitological prevalence at the start of the survey was higher in the fully-sedentary group (9%) than in the partially-sedentary group (3%). In subsequent visits, however, the parasitological incidence was consistently higher in the partially-sedentary group than in the fully-sedentary group. The mean seroprevalence (ELISA) of both groups increased from 3% in March to 54% in December. Statistical analysis of the serological results using a random effect logistic regression, showed a significant difference in incidence of bovine trypanosomosis between the two groups. There was also a significant effect of time. The influence of cattle herding on host-vector-parasite interface and its consequence on the incidence of trypanosomosis are discussed.

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

    NASA Astrophysics Data System (ADS)

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

    2010-04-01

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

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

    SciTech Connect

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

    2007-03-31

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  11. The Cenozoic stress/deformation field of the Donets coal basin and Northern Azov region and its probable sources

    NASA Astrophysics Data System (ADS)

    Kopp, M.; Korchemagin, V.; Kolesnichenko, A.

    2009-04-01

    Studies of structure, development and dynamics of formation of the little-investigated Cenozoic (Alpine) deformations of the Donets Herzinic intraplate orogen (Donets Coal Basin, or Donbass) and Northern Azov region, which were accompanied by mass mesotectonic measurement, revealed traces of two independent Cenozoic orogenies: the Laramic one of the Early Alpine (Latest Cretaceous — Paleocene), and the Recent one of the Late Alpine (Neogene — Quaternary). The orogenies differ in area of manifestation and peculiarities of stress/deformation field. The first orogeny in its pure state developed only in the western Donbass and adjacent relic part of the Dnieper-Donets aulacogene where gentle folds of the Mesozoic strata of the WNW - ESE strike were formed. The folds (so-called Izyum-Kramatorsk structural unit) are sharply overprinted by the Eocene beds and confined to salt diapirs gradually uplifting from the Devonian. According the mesotectonic data, in the post-Cretaceous time they however developed under slight transversal compression with some horizontal shear. The Laramic movements occurred also to the east where they together with the Recent ones participated in formation of the Severodonetskij and Persianovskij border reverse faults of the Donbass. However, as a whole the Recent orogeny developed independently and far to the east of the Laramic one. The Donets-North Azov neotectonic swell which appeared at that time occupies not only the eastern Donets intraplate orogen arised from the Dnieper-Donets aulacogene but strongly crosses the southern aulacogene border extending far into the Ukrainian shield. The different areas of the Laramic and Recent orogenic movements in the Donbass suggest that they raised from different sources. The eastern distribution of the Late Alpine deformation and its more intense manifestation (the well noticeable neotectonic uplift as well as the extension outside the aulacogene and the activization of the Ukrainian shield basement

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

    USGS Publications Warehouse

    Shinneman, Douglas; McIlroy, Susan

    2016-01-01

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

  13. Exploring the Application of Optical Remote Sensing as a Method to Estimate the Depth of Backwater Nursery Habitats of the Colorado Pikeminnow

    SciTech Connect

    Hamada, Yuki; LaGory, Kirk E.

    2016-02-01

    Low-velocity channel-margin habitats serve as important nursery habitats for the endangered Colorado pikeminnow (Ptychocheilus lucius) in the middle Green River between Jensen and Ouray, Utah. These habitats, known as backwaters, are associated with emergent sand bars, and are shaped and reformed annually by peak flows. A recent synthesis of information on backwater characteristics and the factors that influence inter-annual variability in those backwaters (Grippo et al. 2015) evaluated detailed survey information collected annually since 2003 on a relatively small sample of backwaters, as well as reach-wide evaluations of backwater surface area from aerial and satellite imagery. An approach is needed to bridge the gap between these detailed surveys, which estimate surface area, volume, and depth, and the reach-wide assessment of surface area to enable an assessment of the amount of habitat that meets the minimum depth requirements for suitable habitat.

  14. Spatial variation in total element concentration in soil within the Northern Great Plains coal region, and regional soil chemistry in Bighorn and Wind River basins, Wyoming and Montana

    USGS Publications Warehouse

    Severson, R.C.; Tidball, R.R.

    1979-01-01

    PART A: To objectively determine the changes in chemical character of an area subjected to mining and reclamation, prior information is needed. This study represents a broadscale inventory of total chemical composition of the surficial materials of the Northern Great Plains coal region (western North and South Dakota, eastern Montana, and northeastern Wyoming); data are given for 41 elements in A and C soil horizons. An unbalanced, nested, analysis-of-variance design was used to quantify variation in total content of elements between glaciated and unglaciated terrains, for four increasingly smaller geographic scales, and to quantify variation due to sample preparation and analysis. From this statistical study, reliable maps on a regional basis (>100 km) were prepared for C, K, and Rb in A and C soil horizons; for N a, Si, Th, D, and Zn in A-horizon soil; and for As, Ca, Ge, and Mg in C-horizon soil. The distribution of variance components for the remaining 29 elements did not permit the construction of reliable maps. Therefore, a baseline value for each of these elements is given as a measure of the total element concentration in the soils of the Northern Great Plains coal region. The baseline is expressed as the 95-percent range in concentration to be expected in samples of natural soils. PART B: A reconnaissance study of total concentrations of 38 elements in samples of soils (0-40 cm deep, composite) from the Bighorn and Wind River Basins of Montana and Wyoming indicates that the geographic variation for most elements occurs locally (5 km or less). However, in the Bighorn Basin, Zn exhibits significant regional variation (between geologic units); and in the Wind River Basin, AI, Cr, K, Mn, Mo, Ni, U, and V exhibit similar variation. For the remaining elements, the lack of regional variation suggests that a single summary statistic can be used to estimate a baseline value that reflects the range in concentration to be expected in samples of soils in each basin

  15. Climatic variability during the last ˜90 ka of the southern and northern Levantine Basin as evident from marine records and speleothems

    NASA Astrophysics Data System (ADS)

    Almogi-Labin, Ahuva; Bar-Matthews, Miryam; Shriki, Dan; Kolosovsky, Elina; Paterne, Martine; Schilman, Bettina; Ayalon, Avner; Aizenshtat, Zeev; Matthews, Alan

    2009-12-01

    The influence of the northern Atlantic and tropical monsoonal systems, as recorded by the River Nile, on the climate variability of the southeastern Mediterranean was studied in two cores taken by the R/V Marion Dufresne: one core taken SE of Cyprus representing the northern Levantine Basin (core 9501, 980 m water depth) and the other located ˜380 km further south, represents the southeastern Levantine Basin in an area influenced by the River Nile plume (core 9509, 884 m water depth). The study was performed at relatively high resolution using several proxies: δ 18O of Globigerinoides ruber, sediment characteristics and index colour parameters in core sections representing the last 86 ka. A low-resolution alkenone sea surface temperature record was also measured. The time frame in both cores was mostly constrained by 'wiggle' matching with the nearby well-dated δ 18O and δ 13C record of the Soreq Cave, which is mainly influenced by the eastern Mediterranean water vapor. The sedimentary record of the southern core is strongly influenced by the River Nile contribution throughout the last 86 ka, as evidenced by the higher sedimentation rates compared with the northern core (20 cm/ka vs. 5 cm/ka), continuously darker sediment colour, and higher TOC values (0.6-0.9 vs. 0.25 wt% not including sapropels). During sapropels S1 and S3, present in both cores, the influence of the River Nile became more widespread, reaching as far as Cyprus. Yet, the influence of the River Nile remained stronger in the south, as evident by the higher TOC values in the southern core throughout the entire 90 ka period and the longer duration of S1 in the southern core. An anomalous low δ 18O interval that is not recorded in western Mediterranean occurred between 58 and 49 ka in the Levantine Basin and is more developed in the northern core. This period correlates with D-O interstadial 14 and maximum northern hemisphere insolation during the lastglacial cycle, suggesting that the warming

  16. A regional view of urban sedimentary basins in Northern California based on oil industry compressional-wave velocity and density logs

    USGS Publications Warehouse

    Brocher, T.M.

    2005-01-01

    Compressional-wave (sonic) and density logs from 119 oil test wells provide knowledge of the physical properties and impedance contrasts within urban sedimentary basins in northern California, which is needed to better understand basin amplification. These wire-line logs provide estimates of sonic velocities and densities for primarily Upper Cretaceous to Pliocene clastic rocks between 0.1 - and 5.6-km depth to an average depth of 1.8 km. Regional differences in the sonic velocities and densities in these basins largely 1reflect variations in the lithology, depth of burial, porosity, and grain size of the strata, but not necessarily formation age. For example, Miocene basin filling strata west of the Calaveras Fault exhibit higher sonic velocities and densities than older but finer-grained and/or higher-porosity rocks of the Upper Cretaceous Great Valley Sequence. As another example, hard Eocene sandstones west of the San Andreas Fault have much higher impedances than Eocene strata, mainly higher-porosity sandstones and shales, located to the east of this fault, and approach those expected for Franciscan Complex basement rocks. Basement penetrations define large impedence contrasts at the sediment/basement contact along the margins of several basins, where Quaternary, Pliocene, and even Miocene deposits directly overlie Franciscan or Salinian basement rocks at depths as much as 1.7 km. In contrast, in the deepest, geographic centers of the basins, such logs exhibit only a modest impedance contrast at the sediment/basement contact at depths exceeding 2 km. Prominent (up to 1 km/sec) and thick (up to several hundred meters) velocity and density reversals in the logs refute the common assumption that velocities and densities increase monotonically with depth.

  17. Three climatic cycles recorded in a loess-palaeosol sequence at Semlac (Romania) - implications for dust accumulation in the Carpathian Basin and the northern Hemisphere

    NASA Astrophysics Data System (ADS)

    Zeeden, Christian; Hambach, Ulrich; Kels, Holger; Schulte, Philipp; Eckmeier, Eileen; Marković, Slobodan; Klasen, Nicole; Lehmkuhl, Frank

    2016-04-01

    Recent investigations of the Semlac loess section in the Southeastern Carpathian Basin, which is situated at the Mureş River in its lower reaches (Banat region, western Romanian), are presented. Dating back to marine isotope stage (MIS) 10, the more than 10 m thick loess sequence includes four fossil sol-complexes developed in homogenous relatively fine silty loess. Because good preservation and sedimentation of fine silt Semlac is regarded as a key section for the Carpathian Basin, which offers possibilities to a) improve the understanding of the type and composition of the lowland loess sequences in the Carpathian Basin also beyond the last interglacial palaeosol complex, b) to reconstruct the temporal evolution of the local loess-palaeosol successions and c) to compare the loess of the region to loess-sequences in adjacent and dust proxy data in the northern hemisphere. A strikingly sinusoidal course of physical property data with depth/time point to relatively homogenous, quasi-continuous background sedimentation of dust, interpreted as long-range transport (LRT). An integrated age model based on correlation to reference records and luminescence dating is compiled. Applying this age model we compare climate proxy data from Semlac to both global data and to data from the very southeast of the Carpathian Basin (Vojvodina, Serbia). The obtained results provide new insight into the dust accumulation regime in the Carpathian Basin and offer new palaeoenvironmental information for the region and are an important step towards establishing a catena from the thin loess-like sediments of the Banat foothills in the East towards the thicker and seemingly more complete loess sections of the southeastern and central Carpathian Basin. Disentangling grain size data from soil formation proxies gives quantitative estimates for the contribution of original sediment and weathering (through soil formation) to the present clay fraction. Patterns of clay from direct sedimentation

  18. Temporal-spatial distribution of archaeological sites in the Nihewan-Huliu Basin during the Paleolithic-Neolithic and Iron Age in northern China

    NASA Astrophysics Data System (ADS)

    Zhang, J. X.; Wang, X. Y.; Yang, R. X.; Li, X. Z.; Zhang, W.

    2016-11-01

    The Nihewan-Huliu Basin is one of the great regions of human evolution, located in geographical transition zone. This study reveals the temporal-spatial distribution of archaeological sites based on the DEM (Digital Elevation Model) data, and analyses the changes for four periods (Paleolithic-Neolithic transition, Neolithic Age, Bronze Age and Iron Age). These sites expanded from the Sanggan River to the Huliu River and from the central and lower Huliu River to its upper reaches. The population and cultural development in the Nihewan Basin gradually lagged behind the Huliu River Baisin after the Paleolithic-Neolithic transition Age, because of the environmental impacts. The results may aid the understanding and study of the cultural heritage and civilization evolution in northern China.

  19. {open_quotes}Black Gold{close_quotes} leads to new structural interpretation, Northern Sangre de Cristo Mountains/Northeast San Luis Basin

    SciTech Connect

    Watkins, T.A.; Belcher, J.S.; Gries, R.

    1995-06-01

    In the course of exploring for gold along the east margin of the Rio Grande Rift (northern Sangre de Cristo Mountains and northeastern San Luis Basin) live Cretaceous oil was discovered in fractured Precambrian gneiss in 25 of 42 shallow drill holes. Geologic mapping located two outcrops of Mesozoic sediments along the west flank of the Sangre de Cristo Mountains. Mancos Shale, Dakota Group and Morrison Formation sediments were identified from 17 drill holes. These are the first known occurrences of Mesozoic sediments in the area. Previous investigations had concluded that the Mesozoic section eroded from the San Luis uplift during the Laramide. Surface and subsurface geologic data was integrated with gravity, magnetic and seismic surveys for a new structural interpretation. The San Luis Basin is separated from the mountains by an intermediate block and the main basin-bounding fault is three miles west-southwest of the mountain front. A major low-angle, normal fault or detachment fault is related to Miocene rifting. A thick section of Mesozoic sediments are interpreted to be present in the hanging wall of this low angle fault. Buried and thermally matured in a Laramide intermountane basin, these sediments are likely the source of the present day oil found in Precambrian rocks.

  20. Holocene Paleoenvironment of the North-central Great Basin: Preliminary Results from Favre Lake, Northern Ruby Mountains, Nevada

    NASA Astrophysics Data System (ADS)

    Starratt, S.; Wahl, D.; Wan, E.; Anderson, L.; Wanket, J.; Olson, H.; Lloyd-Davies, T.; Kusler, J.

    2009-12-01

    Little is known about Holocene climate variability in north-central Nevada. This study aims to assess changes in watershed vegetation, fire history, lake levels and limnological conditions in order to understand secular to millennial-scale changes in regional climate. Favre Lake (2,899 m a.s.l.; 12 m deep; 7.7 hectares) is a flow-through lake in the northern Ruby Mountains. The primary sources of influent, both of which appear to be intermittent, are Castle Lake (2,989 m a.s.l.) and Liberty Lake (3,077 m a.s.l.). The bedrock of the three lake basins is early Paleozoic marble and Mesozoic granite and metamorphic rocks. Bathymetric maps and temperature, pH, salinity, and conductivity profiles have been generated for Favre Lake. Surface samples and a series of cores were also collected using a modified Livingstone piston corer. The presence of the Mazama ash in the basal sediment (~4 m below the sediment/water interface) indicates the record extends to ~7,700 cal yr B.P. Magnetic susceptibility (MS) and loss-on-ignition data indicate that the sediments in the lowest part of the core contain primary and reworked Mazama ash. About 2,000 years ago CaCO3 increased from 2 to 3% of the inorganic sediment. The upper 25 cm of the core are marked by an increase in MS which may indicate increased erosion due to grazing. Between about 7,700 and 6,000 cal yr B.P. the diatom flora is dominated by a diverse assemblage of benthic species. The remainder of the core is dominated by Fragilaria, suggesting that lake level rose and flooded the shelf that surrounds the depocenter of the lake. This is supported by changes in the abundance of the aquatic fern Isoetes. Pinus and Artemisia dominate the pollen record, followed by subordinate levels of Poaceae, Asteraceae, Amaranthaceae, and Sarcobatus. The late early Holocene (7,700-6,000 cal yr B.P.) is dominated by Pinus which is present in reduced amounts during the middle Holocene (6,000-3,000 cal yr B.P.) and then returns to dominance in

  1. Selection of flooded agricultural fields and other landscapes by female northern pintails wintering in Tulare Basin, California

    USGS Publications Warehouse

    Fleskes, Joseph P.; Jarvis, Robert L.; Gilmer, David S.

    2003-01-01

    Habitat selection and use are measures of relative importance of habitats to wildlife and necessary information for effective wildlife conservation. To measure the relative impor- tance of flooded agricultural fields and other landscapes to northern pintails (Anas acuta) wintering in Tulare Basin (TB), California, we radiotagged female pintails during late August-early October, 1991-1993 in TB and other San Joaquin Valley areas and deter- mined use and selection of these TB landscapes through March each year. Availability of landscape and field types in TB changed within and among years. Pintail use and selec- tion (based upon use-to-availability log ratios) of landscape and field types differed among seasons, years, and diel periods. Fields flooded after harvest and before planting (i.e., pre-irrigated) were the most available, used, and selected landscape type before the hunting season (Prehunt). Safflower was the most available, used, and-except in 1993, when pre-irrigated fallow was available-selected pre-irrigated field type during Prehunt. Pre-irrigated barley-wheat received 19-22% of use before hunting season, but selection varied greatly among years and diel periods. During and after hunting season, managed marsh was the most available, used, and, along with floodwater areas, selected landscape type; pre-irrigated cotton and alfalfa were the least selected field types and accounted for <13% of pintail use. Agricultural drainwater evaporation ponds, sewage treatment ponds, and reservoirs accounted for 42-48% of flooded landscape available but were lit- tle used and least selected. Exodus of pintails from TB coincided with drying of pre-irri- gated fallow, safflower, and barley-wheat fields early in winter, indicating that preferred habitats were lacking in TB during late winter. Agriculture conservation programs could improve TB for pintails by increasing flooding of fallow and harvested safflower and grain fields. Conservation of remaining wetlands should

  2. Late Miocene to Quaternary Transition in Magmatism and Tectonics, Sierra Nevada - Basin and Range Boundary, Northern California-Western Nevada

    NASA Astrophysics Data System (ADS)

    Prytulak, J.; Cousens, B. L.; Henry, C. D.

    2001-12-01

    During the late Miocene and early Pliocene, the Ancestral Cascades Arc (ARC) in northern CA and western NV shut off as the Mendocino triple junction migrated northward. At the same time, Basin and Range extension migrated westward into the Sierra Nevada block, with major episodes at 12 and 3 Ma. These tectonic events are reflected in a complex transition in magmatic composition and style. We are using geochemical, isotopic, and 40Ar/39Ar data to evaluate magma petrogenesis, the timing of volcanism, and the relationship between volcanism and tectonism in this poorly understood region of Mio-Pliocene arc volcanism. The ARC erupted highly porphyritic, pyroxene- or hornblende-plagioclase andesites to dacites, termed the Kate Peak Formation, from numerous stratovolcano complexes over basement rocks of the Sierra Nevada Batholith. Our new and published dating indicate activity from \\sim16 to 4 Ma. Immediately west of Reno, sequences dominated by poorly-phyric, olivine- and pyroxene-basaltic andesite, commonly termed Lousetown Formation, began to erupt as early as 10 Ma and continued to \\sim1 Ma. Early episodes, at 10.3 and 4 Ma, were contemporaneous with continued arc magmatism. Further, post-arc mafic volcanism continued in the area north of Lake Tahoe between 2.9 and 1.2 Ma. Although the change from hydrous intermediate rocks to \\sim anhydrous mafic rocks suggests a fundamental change in magmatic sources and tectonic setting, the mafic rocks have normalized incompatible element patterns and radiogenic isotope compositions that include a strong subduction component that is virtually indistinguishable from that in ARC intermediate lavas. Thus mafic and intermediate magmas, including post-arc magmas, share a common, fluid-modified, mantle wedge source. Additionally, the timing of mafic magmatism coincides only imprecisely with extension. No mafic magmas erupted before the beginning of extension at any location, but the earliest activity followed extension by \\sim2Ma

  3. The Crati River Basin: geomorphological and stratigraphical data for the Plio-Quaternary evolution of northern Calabria, South Apennines, Italy

    NASA Astrophysics Data System (ADS)

    Robustelli, Gaetano; Muto, Francesco

    2017-02-01

    In this paper, we present the results of an integrated geomorphological and stratigraphical study carried out in the eastern side of the Crati River valley (northern Calabria, South Italy). This area is characterized by the occurrence of three order palaeosurfaces that, along with low-sloping palaeovalleys and structural landforms, are striking features of the landscape. The relationships between morpho-tectonic and sedimentary evolution of the Crati Basin has been assessed through sandstone detrital modes, morphostratigraphy and geomorphological correlation with adjacent areas. The two main unconformity surfaces that typify the Quaternary fill were correlated to different steps of landscape evolution. The presence of both erosional and depositional palaeosurfaces has been a useful marker for reconstructing sedimentary and morphogenetic events, and hence to detect drainage network evolution and changes in source sediment area. In particular, we recognized that the study area experienced, during the late Pliocene-Early Pleistocene a period of sub-aerial landscape modelling as suggested by low-sloping palaeovalleys and related fluvial deposits (1st Order Palaeosurface). At that time, the source of the detrital constituents of the PPS Unit sandstones was mainly from the Sila Massif. The onset of Coastal Range identification and uplift (Early Pleistocene) marks a change in the geomorphic scenario with tectonic driven stream incision and valley development along the eastern side of Coastal Range, along with the occurrence of depositional and erosional landsurfaces (2nd Order Palaeosurface) at footslopes. During this period, the Coastal Range and Sila Massif were the sources for the detrital constituents of the PlS Unit sandstones. The progressive uplift of Coastal Range during late Early Pleistocene and the marked backstepping of the depositional systems along the Sila footslope was accompanied by alternating phases of down-cutting and base-level stability resulting in

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

    NASA Astrophysics Data System (ADS)

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

    2008-09-01

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

  5. Palynology, petrography and geochemistry of the Sewickley coal bed (Monongahela Group, Late Pennsylvanian), Northern Appalachian Basin, USA

    USGS Publications Warehouse

    Eble, C.F.; Pierce, B.S.; Grady, W.C.

    2003-01-01

    Forty-two bench samples of the Sewickley coal bed were collected from seven localities in the northern Appalachian Basin and analyzed palynologically, petrographically, and geochemically. The Sewickley coal bed occurs in the middle of the Pittsburgh Formation (Monongahela Group) and is of Late Pennsylvanian age. Palynologically, it is dominated by spores of tree ferns. Tree fern spore taxa in the Sewickley include Punctatisporites minutus, Punctatosporites minutus, Laevigatosporites minimus, Spinosporites exiguus, Apiculatasporites saetiger, and Thymospora spp. In fact, Punctatisporites minutus was so abundant that it had to be removed from the standard counts and recorded separately (average 73.2%). Even when Punctatisporites minutus is removed from the counts, tree fern spores still dominate a majority of the assemblages, averaging 64.4%. Among the tree fern spores identified in the Sewickley coal, Thymospora exhibits temporal and spatial abundance variation. Thymospora usually increases in abundance from the base to the top of the bed. Thymospora is also more abundant in columns that are thick (>100 cm) and low in ash yield (< 12.0%, dry basis). Calamite spores (e.g. Calamospora spp., Laevigatosporites minor, and L. vulgaris) are the next most abundant plant group represented in the Sewickley coal, averaging 20%. Contributions from all other plant groups are minor in comparison. Petrographically, the Sewickley coal contains high percentages of vitrinite (average 82.3%, mineral matter-free (mmf)), with structured forms being more common than unstructured forms. In contrast, liptinite and inertinite macerals both occur in low percentages (average 7.7% and 10.0%, respectively). Geochemically, the Sewickley coal has a moderate ash yield (average 12.4%) and high total sulfur content (average 3.4%). Four localities contained a high ash or carbonaceous shale bench. These benches, which may be coeval, are strongly dominated by tree fern spores. Unlike the lower ash

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

    USGS Publications Warehouse

    Mathany, Timothy M.; Belitz, Kenneth

    2015-01-01

    Chloroform, simazine, and perchlorate were observed in the Interior Basins and Coastal Basins study areas, predominantly at shallow sites with top-of-perforation depths ≤70 feet below land surface, with modern water (post-1950s), and with oxic groundwater conditions.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  8. Late Quaternary landscape evolution in the Kunlun Mountains and Qaidam Basin, Northern Tibet: A framework for examining the links between glaciation, lake level changes and alluvial fan formation

    USGS Publications Warehouse

    Owen, L.A.; Finkel, R.C.; Haizhou, M.; Barnard, P.L.

    2006-01-01

    The Qaidam Basin in Northern Tibet is one of the largest hyper-arid intermontane basins on Earth. Alluvial fans, pediment surfaces, shorelines and a thick succession of sediments within the basin, coupled with moraines and associated landforms in the adjacent high mountain catchments of the Kunlun Mountains, record a complex history of Late Quaternary paleoenvironmental change and landscape evolution. The region provides an ideal natural laboratory to examine the interaction between tectonics and climate within a continent-continent collision zone, and to quantify rates of landscape evolution as controlled by climate and the associated glacial and hydrological changes in hyper-arid and adjacent high-altitude environments. Geomorphic mapping, analysis of landforms and sediments, and terrestrial cosmogenic radionuclide surface exposure and optically stimulated luminescence dating serve to define the timing of formation of Late Quaternary landforms along the southern and northwestern margins of the Qaidam Basin, and in the Burhan Budai Shan of the Kunlun Mountains adjacent to the basin on the south. These dates provide a framework that suggests links between climatic amelioration, deglaciation, lake desiccation and alluvial fan evolution. At least three glacial advances are defined in the Burham Budai Shan of the Kunlun Mountains. On the northern side of this range these occurred in the penultimate glacial cycle or early in the last glacial cycle, during the Last Glacial Maximum (LGM)/Lateglacial and during the Holocene. On the south side of the range, advances occurred during the penultimate glacial cycle, MIS-3, and possibly the LGM, Lateglacial or Holocene. Several distinct phases of alluvial fan sedimentation are likewise defined. Alluvial fans formed on the southern side of the Kunlun Mountains prior to 200 ka. Ice-contact alluvial fans formed during the penultimate glacial and during MIS-3. Extensive incised alluvial fans that form the main valley fills north of

  9. Enhanced sediment delivery in a changing climate in semi-arid mountain basins: Implications for water resource management and aquatic habitat in the northern Rocky Mountains

    NASA Astrophysics Data System (ADS)

    Goode, Jaime R.; Luce, Charles H.; Buffington, John M.

    2012-02-01

    The delivery and transport of sediment through mountain rivers affects aquatic habitat and water resource infrastructure. While climate change is widely expected to produce significant changes in hydrology and stream temperature, the effects of climate change on sediment yield have received less attention. In the northern Rocky Mountains, we expect climate change to increase sediment yield primarily through changes in temperature and hydrology that promote vegetation disturbances (i.e., wildfire, insect/pathogen outbreak, drought-related die off). Here, we synthesize existing data from central Idaho to explore (1) how sediment yields are likely to respond to climate change in semi-arid basins influenced by wildfire, (2) the potential consequences for aquatic habitat and water resource infrastructure, and (3) prospects for mitigating sediment yields in forest basins. Recent climate-driven increases in the severity and extent of wildfire suggest that basin-scale sediment yields within the next few years to decades could be greater than the long-term average rate of 146 T km - 2 year - 1 observed for central Idaho. These elevated sediment yields will likely impact downstream reservoirs, which were designed under conditions of historically lower sediment yield. Episodic erosional events (massive debris flows) that dominate post-fire sediment yields are impractical to mitigate, leaving road restoration as the most viable management opportunity for offsetting climate-related increases in sediment yield. However, short-term sediment yields from experimental basins with roads are three orders of magnitude smaller than those from individual fire-related events (on the order of 10 1 T km - 2 year - 1 compared to 10 4 T km - 2 year - 1 , respectively, for similar contributing areas), suggesting that road restoration would provide a relatively minor reduction in sediment loads at the basin-scale. Nevertheless, the ecologically damaging effects of fine sediment (material < 6 mm

  10. The onset of flood basalt volcanism, Northern Paraná Basin, Brazil: A precise U-Pb baddeleyite/zircon age for a Chapecó-type dacite

    NASA Astrophysics Data System (ADS)

    Janasi, Valdecir de Assis; de Freitas, Vivian Azor; Heaman, Larry H.

    2011-02-01

    We report the first U-Pb baddeleyite/zircon date for a felsic volcanic rock from the Paraná Large Igneous Province in south Brazil. The new date of 134.3 ± 0.8 Ma for a hypocrystalline Chapecó-type dacite from Ourinhos (northern Paraná basin) is an important regional time marker for the onset of flood basalt volcanism in the northern and western portion of the province. The dated dacite was erupted onto basement rocks and is overlain by a high-Ti basalt sequence, interpreted to be correlative with Pitanga basalts elsewhere. This new U-Pb date for the Ourinhos dacite is consistent with the local stratigraphy being slightly older than the few reliable step-heating 40Ar/39Ar dates currently available for overlying high-Ti basalts (133.6-131.5 Ma). This indicates an ~ 3 Ma time span for the building of the voluminous high-Ti lava sequence of the Paraná basin. On the other hand, it overlaps the 40Ar/39Ar dates (134.8-134.1 Ma) available for the stratigraphically older low-Ti basalt (Gramado + Esmeralda types) and dacite-rhyolite (Palmas type) sequences from South Brazil, which is consistent with the short-lived character of this volcanism and its rapid succession by the high-Ti sequence.

  11. Longitudinal evolution of the tectonic style along the Cyprus Arc, northern margin of the Levant and Herodotus Basins

    NASA Astrophysics Data System (ADS)

    Symeou, Vasilis; Homberg, Catherine; Nader, Fadi; Darnault, Romain; Lecomte, Jean-Claude

    2016-04-01

    The Levant Basin is bounded to the north by the Cyprus Arc zone which was created by the northward movement of the African plate with respect to the Eurasian plate since Late Cretaceous time. The westward movement of the Anatolian micro-plate since Late Miocene created an additional strike-slip component along the plate boundary. The main objective of this contribution is to portray the structural architecture and features offshore Cyprus by analyzing available 2D seismic data in order to investigate the transition in tectonic style from compression to strike slip along the Cyprus Arc zone. We identified three different crustal domains offshore Cyprus that are from east to west: the eastern domain which belongs to the Levant Basin, the South-central domain which includes the Eratosthenes Seamount, and the South-West domain of Cyprus which corresponds to the Herodotus Basin. In the Levant Basin, the sequences identified are from Base Pliocene extending until the Senonian unconformity. The same sequences in the Cyprus Basin are offset and less thick due to the movement of the Latakia Ridge, which is identified as a steeply dipping sub-vertical fault on our data. In the central domain, the horizons identified on the Eratosthenes Seamount indicate that the Seamount is a Mesozoic carbonate platform covered by thin Miocene/Plio-Pleistocene sediments. A subdivision of the sedimentary sequence in the Herodotus Basin is proposed down to the Paleocene-Eocene basis. A major change in the structural style of the deformation is observed form west to east. Whereas the Levant Basin is almost undeformed south of the Latakia Ridge, several structures were mapped in the central domain, like flexural basin, pop-up structures and back-thrusts. South-verging thrusts were also, identified in the Cyprus Basin. All these structures show a Pliocene activity. Our data suggest that the heterogeneity of the crustal structure played a major role in the longitudinal evolution of the plate

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

    USGS Publications Warehouse

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

    2016-01-01

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

  13. The Pre-historical Eruption of Volcanoes Near a Capital-city: Inferred From Tephra Deposits in the Taipei Basin, northern Taiwan

    NASA Astrophysics Data System (ADS)

    Chen, C.; Lin, C.

    2006-12-01

    The volcanic pyroclastic flows, lahars and/or ashes derived from volcanic eruptions are a serious threat of human lives and regional economies, especially in the densely populated area. In case, more than two million populations in the capital-city Taipei, northern Taiwan just live in the vicinity of the Tatun Volcanic Group (TVG), how to make effective and reliable volcanic hazard mitigation is absolutely mandatory. Volcano is a pretty complex system. Hazard mitigation can be achieved only by applying numerous techniques. Understanding the recent eruptive history will be the most important information for prediction the future activity of eruption. After 1995, the Center Geological Survey of Ministry of Economic Affair handled to drill more than 20 wells in the Taipei basin to investigate the subsurface geology of basin. These continuous core samples offered the best materials to investigate if any volcanic ashes had deposited in the basin. The young juvenile volcanic ashes V pumice tuff were firstly identified in the two cores of the Kuantu well (KT- 1) and the Shihlin well (SL-1 in the late Pleistocene Sunshan formation. According to the radiocarbon (C-14) ages of core samples (Lin et al, 1998, Shieh, 2001), the time of this tephra deposit was extrapolated around 18.6 kyrs C-14 B.P.. Respecting, this tephra would like to be temperately named as the 18 kyrs Taipei Tuff (18 KTT). These air-fall ash deposits found in the core directly demonstrated that there had been re-active in the TVG in the recent time. More notable thing is that there are three historical records of submarine eruptions in northern offshore Taiwan, then, a program of the volcanic hazard reduction should be seriously considered around the capital city-Taipei.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  15. Non-seismic geophysics compared and integrated with seismic in a frontier oil play: Northern Sangre de Cristo Mountains/Northeast San Luis Basin, Colorado

    SciTech Connect

    Longacre, M.B.; Christopherson, K.R.; Gries, R.

    1995-06-01

    Four non-seismic geophysical tools have made a significant contribution to a new geological interpretation of the northern Sangre de Cristo Mountains/northeast San Luis Basin of south-central Colorado. Gravity, aeromagnetic, magnetotelluric, (MT) and time domain electromagnetic (TDEM) data were acquired and interpreted during the early stages of exploration. Two-dimensional modeling of the gravity and magnetics placed the main, basin-bounding fault three miles southwest of the mountain front, identified an intermediate fault block at the basin margin and identified a thick sequence of non-magnetic, intermediate density rocks on top of this block. A thick section of Mesozoic sediments is interpreted, supported by the discovery of outcrops of Cretaceous sediments and live Cretaceous oil. Magnetotelluric data was acquired to confirm the presence of Mesozoic sediments and depth to basement. Detailed TDEM data has been useful in correlating the MT with surface geology. Integration of the gravity, magnetic and MT data with seismic resulted in minor modifications to the new geological model.

  16. Structure and age of the Lower Magdalena Valley basin basement, northern Colombia: New reflection-seismic and U-Pb-Hf insights into the termination of the central andes against the Caribbean basin

    NASA Astrophysics Data System (ADS)

    Mora-Bohórquez, J. Alejandro; Ibánez-Mejia, Mauricio; Oncken, Onno; de Freitas, Mario; Vélez, Vickye; Mesa, Andrés; Serna, Lina

    2017-03-01

    Detailed interpretations of reflection seismic data and new U-Pb and Hf isotope geochemistry in zircon, reveal that the basement of the Lower Magdalena Valley basin is the northward continuation of the basement terranes of the northern Central Cordillera, and thus that the Lower Magdalena experienced a similar pre-Cenozoic tectonic history as the latter. New U-Pb and Hf analyses of zircon from borehole basement samples retrieved in the basin show that the southeastern region consists of Permo-Triassic (232-300Ma) metasediments, which were intruded by Late Cretaceous (75-89 Ma) granitoids. In the northern Central Cordillera, west of the Palestina Fault System, similar Permo-Triassic terranes are also intruded by Late Cretaceous felsic plutons and display ESE-WNW-trending structures. Therefore, our new data and analyses prove not only the extension of the Permo-Triassic Tahamí-Panzenú terrane into the western Lower Magdalena, but also the along-strike continuity of the Upper Cretaceous magmatic arc of the northern Central Cordillera, which includes the Antioquia Batholith and related plutons. Hf isotopic analyses from the Upper Cretaceous Bonga pluton suggest that it intruded new crust with oceanic affinity, which we interpret as the northern continuation of a Lower Cretaceous oceanic terrane (Quebradagrande?) into the westernmost Lower Magdalena. Volcanic andesitic basement predominates in the northwestern Lower Magdalena while Cretaceous low-grade metamorphic rocks that correlate with similar terranes in the Sierra Nevada de Santa Marta and Guajira are dominant in the northeast, suggesting that the Tahamí-Panzenú terrane does not extend into the northern Lower Magdalena. Although the northeastern region of the Lower Magdalena has a similar NE-SW fabric as the San Lucas Ridge of the northeastern Central Cordillera and the Sierra Nevada de Santa Marta, lithologic and geochronologic data suggest that the San Lucas terrane terminates to the north against the

  17. Stratigraphic and tectonic studies in the central Aquitaine Basin, northern Pyrenees: Constraints on the subsidence and deformation history of a retro-foreland basin

    NASA Astrophysics Data System (ADS)

    Rougier, Géraldine; Ford, Mary; Christophoul, Frédéric; Bader, Anne-Gaëlle

    2016-03-01

    The central North-Pyrenean retrowedge developed on a thinned lithosphere, rich in Keuper evaporites. The behavior of this retro-foreland system is studied using subsidence analyses and a sequentially restored cross-section (120 km, Saint-Gaudens to Castelsarrasin) constrained by new chrono- and lithostratigraphy, surface and subsurface data. During the Late Cretaceous, a first episode of foreland subsidence (E1) produced a narrow marine depocenter (Comminges Basin, 30 km wide), supplied from the east. A synchronous early deformation involved inversion of basement faults and gentle shortening (4.5 km) of the Mesozoic strata above a Keuper decoupling layer. A tectonically quiet period (Q, Paleocene), characterized by a condensed succession (marine and continental), was followed by a second episode of subsidence (E2), basin migration and gentle thick- and thin-skinned shortening (8 km). Continental sedimentation, supplied by the uplifting orogen, first filled a narrow flexural basin (E2, M-L Eocene), then expanded across the Aquitaine Platform (E3, Oligocene-Miocene).

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

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

    The extent to which fluids may leak from sedimentary basins to the seabed is a critical issue for assessing the potential of a basin for carbon capture and storage. The Petrel Sub-basin, located beneath central and eastern Joseph Bonaparte Gulf in tropical northern Australia, was identified as potentially suitable for the geological storage of CO2 because of its geological characteristics and proximity to offshore gas and petroleum resources. In May 2012, a multidisciplinary marine survey (SOL5463) was undertaken to collect data in two targeted areas of the Petrel Sub-basin to facilitate an assessment of its CO2 storage potential. This paper focuses on Area 1 of that survey, a 471 km2 area of sediment-starved shelf (water depths of 78 to 102 m), characterised by low-gradient plains, low-lying ridges, palaeo-channels and shallow pockmarks. Three pockmark types are recognised: small shallow unit pockmarks 10-20 m in diameter (generally <1 m, rarely to 2 m deep), composite pockmarks of 150-300 m diameter formed from the co-location of several cross-cutting pockmarks forming a broad shallow depression (<1 m deep), and pockmark clusters comprised of shallow unit pockmarks co-located side by side (150-300 m width overall, <1 m deep). Pockmark distribution is non-random, focused within and adjacent to palaeo-channels, with pockmark clusters also located adjacent to ridges. Pockmark formation is constrained by AMS 14C dating of in situ mangrove deposits and shells to have begun after 15.5 cal ka BP when a rapid marine transgression of Bonaparte Shelf associated with meltwater pulse 1A drowned coastal mangrove environments. Pockmark development is likely an ongoing process driven by fluid seepage at the seabed, and sourced from CO2 produced in the shallow sub-surface (<2 m) sediment. No evidence for direct connection to deeper features was observed.

  19. Stable Isotopic Constraints on Abiogenic Hydrocarbon gas Contributions to Thermogenic Natural gas Resources in the Northern Appalachian Basin, USA

    NASA Astrophysics Data System (ADS)

    Burruss, R. C.; Laughrey, C. D.

    2006-05-01

    The generation of abiogenic methane by serpentinization or by graphite-water reactions in high-grade metamorphic rocks is well documented by isotopic, fluid inclusion, and petrographic studies. However, geochemical evidence is equivocal for abiogenic generation of higher hydrocarbon gases (ethane through pentane) in economic resources. Thermogenic hydrocarbon gases, generated by thermal cracking of sedimentary organic matter of biological origin, are progressively enriched in 13C as a function of increasing number of carbon atoms in the molecule. The isotopic composition is controlled by the kinetic isotope effect (KIE) during carbon-carbon bond breaking with the largest KIE for methane. Published work on gases in Precambrian rocks in Canada and South Africa suggest that some were generated by abiogenic Fischer-Tropsch type reactions that produced gases with carbon isotopic compositions that are reversed from the thermogenic trend. We have documented reversed isotopic compositions in natural gas accumulations in lower Paleozoic reservoirs of the Appalachian basin regionally from West Virginia and eastern Ohio through Pennsylvania to central New York. The regional accumulation in lower Silurian age strata shows progressive enhancement of the isotopic reversal with increasing depth in the basin. Multivariate analysis of the molecular and isotopic data define an end-member in the deep basin with an approximate composition of 98 mol % CH4, 1-2 mol % C2H6, << 1 mol % C3H8, and δ13C (CH4) = -27 ‰, δ13C (C2H6) = -40 ‰, δ13C (C3H8) = - 41‰. The nominal similarity of isotopic reversals in the gases from Precambrian rocks to those in the lower Paleozoic rocks of the Appalachian basin suggests that abiogenic F-T reactions may have generated some fraction of the gases in the deep basin. Comparison of molecular and hydrogen isotopic compositions show that the gases of putative abiogenic F-T origin are significantly different from Appalachian basin gases. All the

  20. Observed Loss and Ineffectiveness of Mosquito Larvicides Applied to Catch Basins in the Northern Suburbs of Chicago IL, 2014

    PubMed Central

    Harbison, Justin E; Layden, Jennifer E; Xamplas, Christopher; Zazra, Dave; Henry, Marlon; Ruiz, Marilyn O’Hara

    2015-01-01

    In the northeastern part of the greater Chicago metropolitan area, the North Shore Mosquito Abatement District (NSMAD) treats approximately 50,000 catch basins each season with larvicide tablets as part of its effort to reduce local populations of the West Nile virus (WNV) vector Culex pipiens. During the 2014 season, an NSMAD technician monitored a subset of 60–195 basins weekly for 18 weeks among the communities of the District for the presence of mosquitoes. Monitoring found no clear evidence in the reduction of mosquitoes with the use of larvicides, and visual inspections of 211 larvicide-treated basins found that the majority (162, 76.8%) were missing tablets 1–17 weeks after applications. This loss of treatment may be due to the rapid dissolution or flushing of larvicides and would help explain why the larvicide appeared to be ineffective. PMID:25987841

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  2. Imaging 3D geological structure of the Mygdonian basin (Northern Greece) with geological numerical modeling and geophysical methods.

    NASA Astrophysics Data System (ADS)

    Cédric, Guyonnet-Benaize; Fabrice, Hollender; Maria, Manakou; Alexandros, Savvaidis; Elena, Zargli; Cécile, Cornou; Nikolaos, Veranis; Dimitrios, Raptakis; Artemios, Atzemoglou; Pierre-Yves, Bard; Nikolaos, Theodulidis; Kyriazis, Pitilakis; Emmanuelle, Chaljub

    2013-04-01

    The Mygdonian basin, located 30 km E-NE close to Thessaloniki, is a typical active tectonic basin, trending E-NW, filled by sediments 200 to 400 m thick. This basin has been chosen as a European experimental site since 1993 (European Commission research projects - EUROSEISTEST). It has been investigated for experimental and theoretical studies on site effects. The Mygdonian basin is currently covered by a permanent seismological network and has been mainly characterized in 2D and 3D with geophysical and geotechnical studies (Bastani et al, 2011; Cadet and Savvaidis, 2011; Gurk et al, 2007; Manakou et al, 2007; Manakou et al, 2010; Pitilakis et al, 1999; Raptakis et al, 2000; Raptakis et al, 2005). All these studies allowed understanding the influence of geological structures and local site conditions on seismic site response. For these reasons, this site has been chosen for a verification exercise for numerical simulations in the framework of an ongoing international collaborative research project (Euroseistest Verification and Validation Project - E2VP). The verification phase has been made using a first 3D geophysical and geotechnical model (Manakou, 2007) about 5 km wide and 15 km long, centered on the Euroseistest site. After this verification phase, it has been decided to update, optimize and extend this model in order to obtain a more detailed model of the 3D geometry of the entire basin, especially the bedrock 3D geometry which can affect drastically the results of numerical simulations for site effect studies. In our study, we build a 3D geological model of the present-day structure of the entire Mygdonian basin. This "precise" model is 12 km wide, 65 km long and is 400 m deep in average. It has been built using geophysical, geotechnical and geological data. The database is heterogeneous and composed of hydrogeological boreholes, seismic refraction surveys, array microtremor measurements, electrical and geotechnical surveys. We propose an integrated

  3. Regional Survey of Structural Properties and Cementation Patterns of Fault Zones in the Northern Part of the Albuquerque Basin, New Mexico - Implications for Ground-Water Flow

    USGS Publications Warehouse

    Minor, Scott A.; Hudson, Mark R.

    2006-01-01

    Motivated by the need to document and evaluate the types and variability of fault zone properties that potentially affect aquifer systems in basins of the middle Rio Grande rift, we systematically characterized structural and cementation properties of exposed fault zones at 176 sites in the northern Albuquerque Basin. A statistical analysis of measurements and observations evaluated four aspects of the fault zones: (1) attitude and displacement, (2) cement, (3) lithology of the host rock or sediment, and (4) character and width of distinctive structural architectural components at the outcrop scale. Three structural architectural components of the fault zones were observed: (1) outer damage zones related to fault growth; these zones typically contain deformation bands, shear fractures, and open extensional fractures, which strike subparallel to the fault and may promote ground-water flow along the fault zone; (2) inner mixed zones composed of variably entrained, disrupted, and dismembered blocks of host sediment; and (3) central fault cores that accommodate most shear strain and in which persistent low- permeability clay-rich rocks likely impede the flow of water across the fault. The lithology of the host rock or sediment influences the structure of the fault zone and the width of its components. Different grain-size distributions and degrees of induration of the host materials produce differences in material strength that lead to variations in width, degree, and style of fracturing and other fault-related deformation. In addition, lithology of the host sediment appears to strongly control the distribution of cement in fault zones. Most faults strike north to north-northeast and dip 55? - 77? east or west, toward the basin center. Most faults exhibit normal slip, and many of these faults have been reactivated by normal-oblique and strike slip. Although measured fault displacements have a broad range, from 0.9 to 4,000 m, most are <100 m, and fault zones appear to

  4. Holocene environmental changes inferred from biological and sedimentological proxies in a high elevation Great Basin lake in the northern Ruby Mountains, Nevada, USA

    USGS Publications Warehouse

    Wahl, David B.; Starratt, Scott W.; Anderson, Lysanna; Kusler, Jennifer E.; Fuller, Christopher C.; Addison, Jason A.; Wan, Elmira

    2015-01-01

    Multi-proxy analyses were conducted on a sediment core from Favre Lake, a high elevation cirque lake in the northern Ruby Mountains, Nevada, and provide a ca. 7600 year record of local and regional environmental change. Data indicate that lake levels were lower from 7600-5750 cal yr BP, when local climate was warmer and/or drier than today. Effective moisture increased after 5750 cal yr BP and remained relatively wet, and possibly cooler, until ca. 3750 cal yr BP. Results indicate generally dry conditions but also enhanced climatic variability from 3750-1750 cal yr BP, after which effective moisture increased. The timing of major changes in the Favre Lake proxy data are roughly coeval and in phase with those recorded in several paleoclimate studies across the Great Basin, suggesting regional climatic controls on local conditions and similar responses at high and low altitudes.

  5. Seasonal concentrations of organic contaminants at the fall line of the Susquehanna River basin and estimated fluxes to northern Chesapeake Bay, USA

    SciTech Connect

    Foster, G.D.; Lippa, K.A.; Miller, C.V.

    2000-04-01

    Riverine fluxes of several pesticides and other organic contaminants from above the fall line of the Susquehanna River basin to northern Chesapeake Bay, USA, were quantified in 1994. Base flow and storm flow samples collected at the fall line of the river from February to December 1994 were analyzed for both dissolved and particulate phase contaminants. Measured concentrations of the organonitrogen and organophosphorus pesticides varied mainly in response to the timing of their application to agricultural fields. Conversely, the concentrations of the more particle-sorptive contaminants such as polychlorinated biphenyls (PCBs), organochlorine (OC) insecticides, and polycyclic aromatic hydrocarbons (PAHs) were more directly correlated with river flow throughout the year. Annual fluxes were almost entirely in the dissolved phase for the organonitrogen and organophosphorus pesticides, distributed between the dissolved and particulate phases for the PCBs and OC insecticides, and primarily in the particulate phase for the PAHs.

  6. Baltazor KGRA and vicinity, Nevada: geothermal reservoir assessment case study, northern Basin and Range province. Final report, 1 October 1978-31 January 1983

    SciTech Connect

    Wright, T.C.

    1983-01-01

    The Baltazor KGRA and McGee/Painted Hills geothermal prospects are located in northern Humboldt County, Nevada along the northwestern margin of the Basin and Range province. Exploration work other than drilling has included groundwater sampling, a microearthquake study, a geologic literature search and photogeologic mapping, compilation of aeromagnetic and gravity mapping, soil mercury surveying, electrical resistivity and self-potential surveys and detailed hydrothermal alteration mapping. Exploration drilling included 27 shallow temperature gradient holes, four intermediate-depth gradient wells and one 3703-foot deep test, Baltazor 45-14. The deep test penetrated Miocene rhyolite, andesite, basalt and andesitic basalt flows before excessive hold deviation forced an end to drilling and completion as a deep temperature observation well. A temperature survey two weeks after completion obtained a 119.7/sup 0/C (247.4/sup 0/F) reading at survey total depth, 1110 m (3640 feet).

  7. Seasonal concentrations of organic contaminants at the fall line of the Susquehanna River basin and estimated fluxes to northern Chesapeake Bay, USA

    USGS Publications Warehouse

    Foster, G.D.; Lippa, K.A.; Miller, C.V.

    2000-01-01

    Riverine fluxes of several pesticides and other organic contaminants from above the fall line of the Susquehanna River basin to northern Chesapeake Bay, USA, were quantified in 1994. Base flow and storm flow samples collected at the fall line of the river from February to December 1994 were analyzed for both dissolved and particulate phase contaminants. Measured concentrations of the organonitrogen and organophosphorus pesticides varied mainly in response to the timing of their application to agricultural fields. Conversely, the concentrations of the more particle-sorptive contaminants such as polychlorinated biphenyls (PCBs), organochlorine (OC) insecticides, and polycyclic aromatic hydrocarbons (PAHs) were more directly correlated with river flow throughout the year. Annual fluxes were almost entirely in the dissolved phase for the organonitrogen and organophosphorus pesticides, distributed between the dissolved and particulate phases for the PCBs and OC insecticides, and primarily in the particulate phase for the PAHs.

  8. Early Cretaceous shelf-edge deltas of the Baltimore Canyon Trough: principal sources for sediment gravity deposits of the northern Hatteras Basin

    USGS Publications Warehouse

    Poag, C. Wylie; Swift, B. Ann; Schlee, John S.; Ball, Mahlon M.; Sheetz, Linda L.

    1990-01-01

    We present evidence that the principal sources for Early Cretaceous (Berriasian-Valanginian) gravity-flow deposits of the northern Hatteras Basin were three large shelf-edge deltas located along the outer margin of the Baltimore Canyon Trough, ∼ 100 km southeast of Cape Charles, Virginia, Ocean City, Maryland, and Long Branch, New Jersey. Sedimentary detritus from the central Appalachian highlands and the Maryland-Virginia coastal plain was transported across the Early Cretaceous continental shelf to form the Cape Charles and Ocean City deltas, whereas deposits of the Long Branch delta came chiefly from the Adirondack and New England highlands. Each delta supplied sediment gravity flows to large slope aprons and submarine-fan complexes on the Early Cretaceous continental slope and rise. The most conspicuous distributary of sediment on the Early Cretaceous continental rise extends 500 km basinward from the Ocean City delta, where its distal deposits were cored at Deep Sea Drilling Project Site 603.

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

    SciTech Connect

    Pohlmann Karl,Ye Ming

    2012-03-01

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

  10. Genetic mixed-stock analysis of lake-run brown trout Salmo trutta fishery catches in the Inari Basin, northern Finland: implications for conservation and management.

    PubMed

    Swatdipong, A; Vasemägi, A; Niva, T; Koljonen, M-L; Primmer, C R

    2013-09-01

    Genetic mixed-stock analysis (MSA) of wild lake-run brown trout Salmo trutta fishery catches (n = 665) from the Inari Basin (northern Finland) between 2006 and 2008 was carried out using a previously characterized baseline with 30 populations (n = 813) and 13 microsatellite loci. Altogether, 12 populations contributed significantly to mixed-stock fisheries, with the Ivalojoki system being the major contributor (70%) to the total catch. When catches were analysed regionally, geographically nearby populations were the main contributors to the local catches, indicating that a large proportion of S. trutta occupy lacustrine areas near the natal river mouth rather than dispersing throughout the lake. Similarly, far upstream populations contributed insignificantly to catches. These findings have important implications for the conservation and sustainable fishery management of the Inari system.

  11. Geographic Distribution of QCDs Around the Northern Plains Basins of Mars and the Relationship to Lowland Materials

    NASA Technical Reports Server (NTRS)

    Buczkowski, D. L.; Frey, H. V.; McGill, G. E.

    2005-01-01

    It has been suggested that quasicircular depressions (QCDs) without a structural representation in Viking and MOC visible imagery represent buried impact craters [1,2,3,4]. Topographic depressions will form over impact craters buried by a differentially compacting cover material because total cover thickness, and thus total compaction, is greater over the center of completely buried impact craters than their rims [5]. If this is the process by which QCDs form, then only areas of differentially compacting materials should have QCDs. Previous work has established that there is a relationship of surface relief to diameter for QCDs around the Utopia Basin [6]. The slope of the trend of this relationship varies depending on cover thickness, becoming steeper with decreasing thickness [7]. Comparing trendslopes of QCDs around different lowland basins might give us insight into the relative thickness of the cover material in these areas. We explore the geographic distribution of QCDs around the Utopia, Isidis and Acidalia basins and compare their location to geologic units and materials. We also compare evidence for relative thickness of cover material at the three basins.

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

    PubMed

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

    2016-01-15

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

  13. The pore structure and fractal characteristics of shales with low thermal maturity from the Yuqia Coalfield, northern Qaidam Basin, northwestern China

    NASA Astrophysics Data System (ADS)

    Hou, Haihai; Shao, Longyi; Li, Yonghong; Li, Zhen; Zhang, Wenlong; Wen, Huaijun

    2016-12-01

    The continental shales from the Middle Jurassic Shimengou Formation of the northern Qaidam Basin, northwestern China, have been investigated in recent years because of their shale gas potential. In this study, a total of twenty-two shale samples were collected from the YQ-1 borehole in the Yuqia Coalfield, northern Qaidam Basin. The total organic carbon (TOC) contents, pore structure parameters, and fractal characteristics of the samples were investigated using TOC analysis, low-temperature nitrogen adsorption experiments, and fractal analysis. The results show that the average pore size of the Shimengou shales varied from 8.149 nm to 20.635 nm with a mean value of 10.74 nm, which is considered mesopore-sized. The pores of the shales are mainly inkbottle- and slit-shaped. The sedimentary environment plays an essential role in controlling the TOC contents of the low maturity shales, with the TOC values of shales from deep to semi-deep lake facies (mean: 5.23%) being notably higher than those of the shore-shallow lake facies (mean: 0.65%). The fractal dimensions range from 2.4639 to 2.6857 with a mean of 2.6122, higher than those of marine shales, which indicates that the pore surface was rougher and the pore structure more complex in these continental shales. The fractal dimensions increase with increasing total pore volume and total specific surface area, and with decreasing average pore size. With increasing TOC contents in shales, the fractal dimensions increase first and then decrease, with the highest value occurring at 2% of TOC content, which is in accordance with the trends between the TOC and both total specific surface area and total pore volume. The pore structure complexity and pore surface roughness of these low-maturity shales would be controlled by the combined effects of both sedimentary environments and the TOC contents.

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

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

    PubMed

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

    2015-05-01

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

  16. Two distinct episodes of Cenozoic extension in the northern Basin and Range Province, as indicated by magmatic and structural characteristics

    SciTech Connect

    Miller, D.M. )

    1993-04-01

    Although some workers in the central and southern Great Basin, Nevada and Utah, hold that Cenozoic crustal extension took place as a single, protracted episode that continues today, many studies indicate that two episodes took place. The distinction between episodes is especially clear in the northeastern Great Basin, where initial extension took place about 40--36 Ma, and extension was renewed from about 18 Ma to present. It appears that the early episode of extension was characterized by WSW hyperextension in north-trending linear zones, now about 130 km apart. Extension took place at the time of voluminous calc-alkaline intermediate to felsic magmatism, but magmatism was regional and not limited to the zones of extension. The first episode began later to the south, paralleling the southward progression of Great Basin magmatism as well as arc magmatism near the west coast. Later extension (Basin and Range sensu stricto) was WNW-directed and was initiated between 17 and 13 Ma region wide; it was accompanied by fundamentally basaltic magmatism throughout the region. Striking differences between the two extensional episodes indicates fundamentally different causes. Extensional zones of the early event were not localized by formerly thickened lithosphere, but rather appear to represent a periodic instability with characteristic wavelength of 80--100 km. The Basin and Range event was initiated during reorganization of the former subduction zone at the North American margin into lengthy transform margin, and coincided with the start of the eastern Snake River and Rio Grande rifts. Magmatism involved the crust less than in the early event.

  17. Spatial distribution of hydrocarbon reservoirs in the West Korea Bay Basin in the northern part of the Yellow Sea, estimated by 3-D gravity forward modelling

    NASA Astrophysics Data System (ADS)

    Choi, Sungchan; Ryu, In-Chang; Götze, H.-J.; Chae, Y.

    2017-01-01

    Although an amount of hydrocarbon has been discovered in the West Korea Bay Basin (WKBB), located in the North Korean offshore area, geophysical investigations associated with these hydrocarbon reservoirs are not permitted because of the current geopolitical situation. Interpretation of satellite-derived potential field data can be alternatively used to image the 3-D density distribution in the sedimentary basin associated with hydrocarbon deposits. We interpreted the TRIDENT satellite-derived gravity field data to provide detailed insights into the spatial distribution of sedimentary density structures in the WKBB. We used 3-D forward density modelling for the interpretation that incorporated constraints from existing geological and geophysical information. The gravity data interpretation and the 3-D forward modelling showed that there are two modelled areas in the central subbasin that are characterized by very low density structures, with a maximum density of about 2000 kg m-3, indicating some type of hydrocarbon reservoir. One of the anticipated hydrocarbon reservoirs is located in the southern part of the central subbasin with a volume of about 250 km3 at a depth of about 3000 m in the Cretaceous/Jurassic layer. The other hydrocarbon reservoir should exist in the northern part of the central subbasin, with an average volume of about 300 km3 at a depth of about 2500 m.

  18. Spatial distribution of Hydrocarbon Reservoirs in the West Korea Bay Basin in the northern part of the Yellow Sea, estimated by 3D gravity forward modeling

    NASA Astrophysics Data System (ADS)

    Choi, Sungchan; Ryu, In-Chang; Götze, H.-J.; Chae, Y.

    2016-10-01

    Although an amount of hydrocarbon has been discovered in the West Korea Bay Basin (WKBB), located in the North Korean offshore area, geophysical investigations associated with these hydrocarbon reservoirs are not permitted because of the current geopolitical situation. Interpretation of satellite- derived potential field data can be alternatively used to image the three-dimensional (3D) density distribution in the sedimentary basin associated with hydrocarbon deposits. We interpreted the TRIDENT satellite-derived gravity field data to provide detailed insights into the spatial distribution of sedimentary density structures in the WKBB. We used 3D forward density modeling for the interpretation that incorporated constraints from existing geological and geophysical information. The gravity data interpretation and the 3D forward modeling showed that there are two modeled areas in the central subbasin that are characterized by very low density structures, with a maximum density of about 2000 kg/m3, indicating some type of hydrocarbon reservoir. One of the anticipated hydrocarbon reservoirs is located in the southern part of the central subbasin with a volume of about 250 km3 at a depth of about 3000 m in the Cretaceous/Jurassic layer. The other hydrocarbon reservoir should exist in the northern part of the central subbasin, with an average volume of about 300 km3 at a depth of about 2500 m.

  19. [Karyological differences of the Northern Dolly Varden Salvelinus malma malma and the white char Salvelinus albus from the Kamchatka River basin].

    PubMed

    Frolov, S V

    2001-03-01

    The karyotypes of northern Dolly Varden and white char, sympathrically inhabiting the Kamchatka River basin, were studied. The karyotype of Dolly Varden was stable: 2n = 78 and NF = 98 + 2, while in white char, polymorphism and mosaicism for the chromosome number were revealed: 2n = 76-79, NF = 98 + 2. Using a routine chromosome staining technique, the karyotype of white char (2n = 78) was shown to be identical to that of Dolly Varden. In both karyotypes, similar sets of marker chromosomes were present: two pairs of submetacentric (SM), one pair of submeta-subtelocentric (SM-ST), one pair of large acrocentric (A), and one pair of large sub-telocentric (ST) chromosomes. However, the karyotypes of Dolly Varden and white char differed in the number and location of nucleolus organizer regions (NORs). In Dolly Varden, single NORs located in the telomeric regions of the marker SM-ST chromosomes were observed. In white char, NORs were multiple and located both in the telomeric regions of the marker SM-ST chromosomes and on the short and long arms of large ST chromosomes. The identical marker chromosomes indicate considerable phylogenetic relatedness between Dolly Varden and white char from the Kamchatka River basin. Variation in NORs provides evidence for the reproductive isolation of these chars and their species status.

  20. Tectonic inversion and magmatism in the Lautaro Basin, northern Chile, Central Andes: A comparative approach from field data and analog models

    NASA Astrophysics Data System (ADS)

    Martínez, Fernando; Bonini, Marco; Montanari, Domenico; Corti, Giacomo

    2016-03-01

    We present the results of a series of analog models addressing the relationships between tectonic inversion and magmatism, taking the Lautaro Basin in northern Chile (27-28° S), Central Andes as a natural case. The experiments consisted of extension and orthogonal shortening of sand-silicone models to reproduce the tectonic inversion of a previous extensional system synchronous with the emplacement of analog magma. We analyzed how the variation in the rate of magma intrusion, shortening, and syn-compressive sedimentation may affect the final configuration of an inverted system, and the results were compared with field observations. Our results showed that (i) folding of syn-rift deposits and increased steepness of the master faults accommodate the shortening of the extensional system, (ii) magmatic intrusions condition the final geometries (top view and cross-section) of inverted normal faults in the models and in the Lautaro Basin, (iii) magma tends to migrate preferentially along the inverted faults, and accumulates beneath the faults and in the core of the inversion anticlines, (iv) the syn-inversion magmatism may indicate the migration pathways, which favor major lubrication and slip on the structures during their reactivation.

  1. Regional geohydrology of the northern Louisiana salt-dome basin; Part II, Geohydrologic maps of the Tertiary aquifers and related confining layers

    USGS Publications Warehouse

    Ryals, G.N.

    1984-01-01

    Regional geohydrologic maps show the altitude of the base and the thickness of the aquifers of Tertiary age and related confining layers in the northern Louisiana salt-dome basin. The limit of freshwater in aquifers is also shown. The basin has an area of about 3,000 square miles, and four geologic units of Tertiary age contain regional aquifers. From oldest (deepest) to youngest, the aquifers are in the Wilcox Group, Carrizo Sand, Sparta Sand, and Cockfield Formation. As the Wilcox is hydraulically interconnected with the overlying Carrizo, they are treated as one hydrologic unit, the Wilcox-Carrizo aquifer. The aquifers are separated by confining layers that retard water movement. In the northwestern part of the area, the Wilcox-Carrizo aquifer is separated from the underlying sand facies of the Nacatoch Sand (Cretaceous age) by a confining layer composed of the Midway Group (Tertiary age) and the underlying Arkadelphia Marl and an upper clay and marl facies of the Nacatoch Sand (both of Cretaceous age). In the remainder of the area, the Wilcox-Carrizo aquifer is separated from an underlying Cretaceous aquifer comprised of the Tokio Formation and Brownstown Marl by the Midway Group and several underlying Cretaceous units which in order of increasing age are the Arkadelphia Maril, Nacatoch Sand, Saratoga Chalk, Marlbrook Marl , and Annona Chalk. The Wilcox-Carrizo aquifer is separated from the Sparta aquifer by the overyling Cane River Formation. The Sparta aquifer is separated from the Cockfield aquifer by the overlying Cook Mountain Formation. (USGS)

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

    PubMed

    Baron, Matthew G

    2015-01-01

    Mesacanthus is a common and speciose genus of acanthodian fish from Lower Old Red Sandstone and Middle Old Red Sandstone assemblages (representing the Lower Devonian and Middle Devonian respectively) and is well represented in many palaeoichthyology collections in the UK. Based upon descriptions given during the 19th century, specimens of the genus Mesacanthus from the Orcadian Basin and Midland Valley areas of Northern and Central Scotland have historically been referred to a number of different species; of these, the most frequently discussed in the literature are M. mitchelli, M. peachi and M. pusillus. In order to test the validity of these three species, traditional morphometric analyses were carried out on over 100 specimens of Mesacanthus, from both the Lower Devonian and the Middle Devonian, that cover the full range of known localities for these taxa in Northern and Central Scotland. Based upon morphological and morphometric comparisons, this investigation has found that at least two species of Mesacanthus are valid (M. mitchelli and M. pusillus) as specimens from the Lower Devonian and Middle Devonian have been shown to differ significantly in a number of important ways. However, no evidence has been found for the validity of the second and distinct Middle Devonian species, M. peachi.

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

    USGS Publications Warehouse

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

    2015-07-14

    The groundwater-level measurements were used to construct a generalized potentiometric-surface map of the Green River Basin lower Tertiary aquifer system. Groundwater-level altitudes measured in nonflowing and flowing wells used to construct the potentiometric-surface map ranged from 6,451 to 7,307 feet (excluding four unmeasured flowing wells used for contour construction purposes). The potentiometric-surface map indicates that groundwater in the study area generally moves from north to south, but this pattern of flow is altered locally by groundwater divides, groundwater discharge to the Green River, and possibly to a tributary river (Big Sandy River) and two reservoirs (Fontenelle and Big Sandy Reservoirs).

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

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

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

  5. Winters-Domengine Total Petroleum System—Northern Nonassociated Gas Assessment Unit of the San Joaquin Basin Province: Chapter 21 in Petroleum systems and geologic assessment of oil and gas in the San Joaquin Basin Province, California

    USGS Publications Warehouse

    Hosford Scheirer, Allegra; Magoon, Leslie B.

    2008-01-01

    The Northern Nonassociated Gas Assessment Unit (AU) of the Winters-Domengine Total Petroleum System of the San Joaquin Basin Province consists of all nonassociated gas accumulations in Cretaceous, Eocene, and Miocene sandstones located north of township 15 South in the San Joaquin Valley. The northern San Joaquin Valley forms a northwest-southeast trending asymmetrical trough. It is filled with an alternating sequence of Cretaceous-aged sands and shales deposited on Franciscan Complex, ophiolitic, and Sierran basement. Eocene-aged strata unconformably overlie the thick Cretaceous section, and in turn are overlain unconformably by nonmarine Pliocene-Miocene sediments. Nonassociated gas accumulations have been discovered in the sands of the Panoche, Moreno, Kreyenhagen, andDomengine Formations and in the nonmarine Zilch formation of Loken (1959) (hereafter referred to as Zilch formation). Most hydrocarbon accumulations occur in low-relief, northwest-southeast trending anticlines formed chiefly by differential compaction of sediment and by northeast southwest directed compression during the Paleogene (Bartow, 1991) and in stratigraphic traps formed by pinch out of submarine fan sands against slope shales. To date, 176 billion cubic feet (BCF) of nonassociated recoverable gas has been found in fields within the assessment unit (table 21.1). A small amount of biogenic gas forms near the surface of the AU. Map boundaries of the assessment unit are shown in figures 21.1 and 21.2; in plan view, this assessment unit is identical to the Northern Area Nonassociated Gas play 1007 considered by the U.S. Geological Survey (USGS) in its 1995 National Assessment (Beyer, 1996). The AU is bounded on the east by the mapped limits of Cretaceous sandstone reservoir rocks and on the west by the east flank of the Diablo Range. The southern limit of the AU is the southernmost occurrence of nonassociated thermogenic-gas accumulations. The northern limit of the AU corresponds to the

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

    USGS Publications Warehouse

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

    2015-01-01

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

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

    PubMed Central

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

    2014-01-01

    Empirical evidence supports wild birds as playing a role in the interhemispheric exchange of bacteria and viruses; however, data supporting the redistribution of parasites among continents are limited. In this study, the hypothesis that migratory birds contribute to the redistribution of parasites between continents was tested by sampling northern pintails (Anas acuta) at locations throughout the North Pacific Basin in North America and East Asia for haemosporidian infections and assessing the genetic evidence for parasite exchange. Of 878 samples collected from birds in Alaska (USA), California (USA), and Hokkaido (Japan) during August 2011–May 2012 and screened for parasitic infections using molecular techniques, Leucocytozoon, Haemoproteus, and Plasmodium parasites were detected in 555 (63%), 44 (5%), and 52 (6%) samples, respectively. Using an occupancy modeling approach, the probability of detecting parasites via replicate genetic tests was estimated to be high (ρ > 0.95). Multi-model inference supported variation of Leucocytozoon parasite prevalence by northern pintail age class and geographic location of sampling in contrast to Haemoproteus and Plasmodium parasites for which there was only support for variation in parasite prevalence by sampling location. Thirty-one unique mitochondrial DNA haplotypes were detected among haematozoa infecting northern pintails including seven lineages shared between samples from North America and Japan. The finding of identical parasite haplotypes at widely distributed geographic locations and general lack of genetic structuring by continent in phylogenies for Leucocytozoon and Plasmodium provides evidence for intercontinental genetic exchange of haemosporidian parasites. Results suggest that migratory birds, including waterfowl, could therefore facilitate the introduction of avian malaria and other haemosporidia to novel hosts and spatially distant regions. PMID:25830100

  8. The evolution of a terrace sequence along the Manas River in the northern foreland basin of Tian Shan, China, as inferred from optical dating

    NASA Astrophysics Data System (ADS)

    Gong, Zhijun; Li, Sheng-Hua; Li, Bo

    2014-05-01

    The Tian Shan range lies in the actively deforming part of the India-Asia collision zone. The uplift rate and deformation pattern of the Tian Shan are important for understanding the dynamics of crustal deformation in the region. The river terraces in northern Tian Shan provide key records of past changes in climate and/or regional tectonics. In this study, a terrace sequence along the Manas River in a tectonically active zone in the northern foreland basin of Tian Shan is investigated. Six river terraces were identified and dated using optically stimulated luminescence (OSL). The results show that the six terraces were abandoned at ~ 0.5 ka, ~ 1.4 ka, ~ 3.1 ka, ~ 4.0 ka, ~ 12.4 ka and ~ 19.9 ka, respectively. Together with high resolution Global Positioning System (GPS) measurements on the terrace treads, the fluvial history of Manas River is reconstructed. From ~ 20 ka to ~ 4.8 ka, the height of the fluvial bed of Manas River decreased at an average rate of 2.2 ± 0.6 mm/yr. From ~ 4.8 ka to the present, the height of the fluvial bed decreased at an average rate of 13.5 ± 0.6 mm/yr, corresponding to intensified incision of Manas River during the late Holocene. This accelerated incision is very likely caused by the tectonic forces rather than climatic influences alone, suggesting that the tectonic uplift activity was significantly intensified since ~ 4.8 ka in the northern piedmont of Tian Shan. Other controlling factors on the incision of Manas River are also discussed.

  9. Rock magnetic properties of an 8-Ma terrigenous succession from the nor