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Sample records for adjacent basinal deposits

  1. Spatio-temporal evolution of a Tertiary carbonate platform margin and adjacent basinal deposits

    NASA Astrophysics Data System (ADS)

    Wilson, Moyra E. J.; Chambers, John L. C.; Manning, Christina; Nas, Dharma S.

    2012-10-01

    The variability in low to moderate energy carbonate platform margins is poorly known from the geological record. Here, the spatial and temporal evolution of platform margin and adjacent basinal deposits is evaluated from the little known Tertiary Kedango Limestone that developed in a semi-enclosed marine embayment in SE Asia. The hypothesis here is that platform margin development will reflect regional and perhaps global influences, such as tectonics, eustasy or biotic change, rather than windward-leeward effects and storms that typically impact strongly upon open oceanic platforms. The development of the carbonate platform was determined through logging, petrography, facies evaluation, provenance and high-resolution dating studies. Eleven carbonate facies were identified from the 30 km long western margin of the > 600 m thick platform and its adjacent slope and basinal deposits. Larger benthic foraminifera and coralline algal packstones and wackestones dominated in shallow waters. During the Oligo-Miocene, coral patch reef-related floatstones, rudstones and less commonly boundstones were also present on the platform top. Perhaps surprisingly for a low energy platform there was considerable variation along the platform margin and much reworking of material into slope and basinal deposits during the Oligo-Miocene. Reworked material includes shallow water bioclasts, clasts from older siliciclastics, fresh feldspars, lithified slope and platform top carbonate clasts, some of the latter showing evidence for karstification. The western platform margin varied laterally over a few kilometres from a gently sloping unrimmed platform, to a probable bank top, with in places coral-fringed, bypass and erosional faulted escarpment margins. Eustasy may have influenced shallowing and deepening trends on the platform top, but apparently had little impact on mass wasting. Instead platform margin development was strongly impacted by tectonics (including active faulting), terrestrial

  2. Morphologic Variability of two Adjacent Mass-Transport Deposits: Twin Slides, Gela Basin (Sicily Channel).

    NASA Astrophysics Data System (ADS)

    Minisini, D.; Trincardi, F.; Asioli, A.; Canu, M.; Foglini, F.

    2006-12-01

    Integrating geophysical, sedimentological, structural and paleontological data, we reconstruct the age, size and internal geometry of two adjacent and recent mass-transport deposits (Twin Slides) exposed on the seafloor of Gela Basin (Sicily Channel). Twin Slides are coeval (late-Holocene), and were likely triggered by an earthquake. Twin Slides originated from the mobilization of Pleistocene slope units, are only 6 km apart from each other, have their headscarps in similar water depth (230 m), and have a comparable run out distance (ca. 10 km). Both slides suggest a multistage evolution, but differ in internal organization and morphological expression. The northern slide shows a deposit characterised by pressure ridges in the toe region suggesting a component of plastic deformation, while the southern slide is characterised by large blocks and a reduced thickness of displaced masses. We ascribe the difference in deformation style and resulting morphology to the stratigraphic architecture of the Pleistocene progradational units involved in failure. In the case of the blocky southern slide the units affected by failure are slightly older (Eemian or pre-Emian) and more consolidated; furthermore, in the area where the headscarp is located these units appear affected by shallow faulting likely resulting in the definition of large blocks. The northern slide, instead, affects progradational units of the Last Glacial Maximum in an area where these units are more than 100 m thick and, possibly, underconsolidated.

  3. Origin, transport and deposition of leaf-wax biomarkers in the Amazon Basin and the adjacent Atlantic

    NASA Astrophysics Data System (ADS)

    Häggi, Christoph; Sawakuchi, André O.; Chiessi, Cristiano M.; Mulitza, Stefan; Mollenhauer, Gesine; Sawakuchi, Henrique O.; Baker, Paul A.; Zabel, Matthias; Schefuß, Enno

    2016-11-01

    Paleoenvironmental studies based on terrigenous biomarker proxies from sediment cores collected close to the mouth of large river systems rely on a proper understanding of the processes controlling origin, transport and deposition of biomarkers. Here, we contribute to the understanding of these processes by analyzing long-chain n-alkanes from the Amazon River system. We use the δD composition of long-chain n-alkanes from river bed sediments from the Amazon River and its major tributaries, as well as marine core-top samples collected off northeastern South America as tracers for different source areas. The δ13C composition of the same compounds is used to differentiate between long-chain n-alkanes from modern forest vegetation and petrogenic organic matter. Our δ13C results show depleted δ13C values (-33 to -36‰) in most samples, indicating a modern forest source for most of the samples. Enriched values (-31 to -33‰) are only found in a few samples poor in organic carbon indicating minor contributions from a fossil petrogenic source. Long-chain n-alkane δD analyses show more depleted values for the western tributaries, the Madeira and Solimões Rivers (-152 to -168‰), while n-alkanes from the lowland tributaries, the Negro, Xingu and Tocantins Rivers (-142 to -154‰), yield more enriched values. The n-alkane δD values thus reflect the mean annual isotopic composition of precipitation, which is most deuterium-depleted in the western Amazon Basin and more enriched in the eastern sector of the basin. Samples from the Amazon estuary show a mixed long-chain n-alkane δD signal from both eastern lowland and western tributaries. Marine core-top samples underlying the Amazon freshwater plume yield δD values similar to those from the Amazon estuary, while core-top samples from outside the plume showed more enriched values. Although the variability in the river bed data precludes quantitative assessment of relative contributions, our results indicate that long

  4. Pliocene transpressional modification of depositional basins by convergent thrusting adjacent to the "Big Bend" of the San Andreas fault: An example from Lockwood Valley, southern California

    USGS Publications Warehouse

    Kellogg, K.S.; Minor, S.A.

    2005-01-01

    The "Big Bend" of the San Andreas fault in the western Transverse Ranges of southern California is a left stepping flexure in the dextral fault system and has long been recognized as a zone of relatively high transpression compared to adjacent regions. The Lockwood Valley region, just south of the Big Bend, underwent a profound change in early Pliocene time (???5 Ma) from basin deposition to contraction, accompanied by widespread folding and thrusting. This change followed the recently determined initiation of opening of the northern Gulf of California and movement along the southern San Andreas fault at about 6.1 Ma, with the concomitant formation of the Big Bend. Lockwood Valley occupies a 6-km-wide, fault-bounded structural basin in which converging blocks of Paleoproterozoic and Cretaceous crystalline basement and upper Oligocene and lower Miocene sedimentary rocks (Plush Ranch Formation) were thrust over Miocene and Pliocene basin-fill sedimentary rocks (in ascending order, Caliente Formation, Lockwood Clay, and Quatal Formation). All the pre-Quatal sedimentary rocks and most of the Pliocene Quatal Formation were deposited during a mid-Tertiary period of regional transtension in a crustal block that underwent little clockwise vertical-axis rotation as compared to crustal blocks to the south. Ensuing Pliocene and Quaternary transpression in the Big Bend region began during deposition of the poorly dated Quatal Formation and was marked by four converging thrust systems, which decreased the areal extent of the sedimentary basin and formed the present Lockwood Valley structural basin. None of the thrusts appears presently active. Estimated shortening across the center of the basin was about 30 percent. The fortnerly defined eastern Big Pine fault, now interpreted to be two separate, oppositely directed, contractional reverse or thrust faults, marks the northwestern structural boundary of Lockwood Valley. The complex geometry of the Lockwood Valley basin is similar

  5. MTR COOLING TOWER. BASIN IS ADJACENT TO PUMP HOUSE. CAMERA ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    MTR COOLING TOWER. BASIN IS ADJACENT TO PUMP HOUSE. CAMERA FACES SOUTHEAST TOWARD NORTH SIDE OF PUMP HOUSE. INL NEGATIVE NO. 2690. Unknown Photographer, 6/1951. - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

  6. Correlation of sea level falls interpreted from atoll stratigraphy with turbidites in adjacent basins

    SciTech Connect

    Lincoln, J.M. )

    1990-05-01

    Past sea levels can be derived from any atoll subsurface sediments deposited at or near sea level by determining the ages of deposition and correcting the present depths to the sediments for subsidence of the underlying edifice since the times of deposition. A sea level curve constructed by this method consists of discontinuous segments, each corresponding to a period of rising relative sea level and deposition of a discrete sedimentary package. Discontinuities in the sea level curve derived by this method correspond to relative sea level falls and stratigraphic hiatuses in the atoll subsurface. During intervals of relative sea level fall an atoll emerges to become a high limestone island. Sea level may fluctuate several times during a period of atoll emergence to become a high limestone island. Sea level may fluctuate several times during a period of atoll emergence without depositing sediments on top of the atoll. Furthermore, subaerial erosion may remove a substantial part of the depositional record of previous sea level fluctuations. For these reasons the authors must look to the adjacent basins to complement the incomplete record of sea level change recorded beneath atolls. During lowstands of sea level, faunas originally deposited near sea level on an atoll may be eroded and redeposited as turbidites in deep adjacent basins. Three such turbidites penetrated during deep-sea drilling at Sites 462 and 315 in the central Pacific correlate well with a late Tertiary sea level curve based on biostratigraphic ages and {sup 87}Sr/{sup 86}Sr chronostratigraphy for core from Enewetak Atoll in the northern Marshall Islands. Further drilling of the archipelagic aprons adjacent to atolls will improve the sea level history that may be inferred from atoll stratigraphy.

  7. 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

  8. Laramide structure of the central Sangre de Cristo Mountains and adjacent Raton Basin, southern Colorado

    USGS Publications Warehouse

    Lindsey, D.A.

    1998-01-01

    erosion of a highland is the appearance of abundant feldspar in the Late Cretaceous Vermejo Formation. Above the Vermejo, unconformities overlain by conglomerate indicate continued thrusting and erosion of highlands from late Cretaceous (Raton) through Eocene (Cuchara) time. Eocene alluvial-fan conglomerates in the Cuchara Formation may represent erosion of the Culebra thrust block. Deposition in the Raton Basin probably shifted north from New Mexico to southern Colorado from Paleocene to Eocene time as movement on individual thrusts depressed adjacent segments of the basin.

  9. Stratigraphic reference section for Georges Bank Basin - depositional model for New England passive margin.

    USGS Publications Warehouse

    Poag, C.W.

    1982-01-01

    A multichannel seismic reflection profile (US Geological Survey line 19), calibrated with the COST G-1, COST G-2, and Shell Mohican I-100 wells, and seismic-sequence analysis shows that the chronostratigraphic and lithostratigraphic units and depositional history of the Georges Bank basin are similar to those of the Scotian basin. Tentative correlation between the Georges Bank basin sequences and those of the adjacent, deep N American basin suggests that the deep-sea facies were strongly influenced by depositional events on the shelf. Deposition in both areas has been sensitive to changes in sea level and the palaeoclimatic cycles.-Author

  10. A review of sediment quantity issues: examples from the River Ebro and adjacent basins (Northeastern Spain).

    PubMed

    Batalla, Ramon J; Vericat, Damià

    2011-04-01

    Sediment flows naturally through the drainage network, from source areas to deposition zones. Sedimentary disequilibrium in rivers and coastlines is related to the imbalance within the fluvial system caused mostly by dams, instream mining, and changes in land use. This phenomenon is also responsible for ecological perturbations in rivers and streams. A broad need exists to establish comprehensive management strategies (soft measures) that would go beyond site-specific engineering practices (technical measures) typically taken to solve particular problems. Long-term programs are also required to monitor sediment transport in river basins, in order to assess the magnitude and variability of sediment transfer and potential deficits. This paper shows examples of rivers with important sediment disequilibrium in the Ebro and adjacent basins. These basins, like most in the Iberian Peninsula, experience sediment discontinuity in the catchment-river-coast system. Reservoir siltation is the main quantitative issue. Land use change and especially gravel mining downstream from dams accentuate the process. We also present and discuss recent developments on water and sediment management undertaken to improve the morphosedimentary dynamics of rivers.

  11. Deposition and evolution of the Sivas basin evaporites (Turkey)

    NASA Astrophysics Data System (ADS)

    Pichat, Alexandre; Hoareau, Guilhem; Rouchy, Jean-Marie; Ribes, Charlotte; Kergaravat, Charlie; Callot, Jean-Paul; Ringenbach, Jean-Claude

    2015-04-01

    The Oligo-Miocene Sivas basin (Turkey) is strongly affected by salt tectonics, best expressed in its central part. Halokinesis initiated from the Upper Eocene Hafik formation, composed of thick evaporite layers. Salt tectonics induced the formation of numerous mini basins filled with continental to marine deposits, and nowadays separated by diapiric gypsum walls or welds. Continental deposits filling minibasins developed in arid conditions. Minibasin sandstones are frequently interlayered with evaporitic deposits (gypsum and anhydrite). Two types of depositional evaporites can be distinguished: (i) evaporites precipitated in lacustrine to sebkhaic environment, (ii) gypsarenites resulting from clastic gypsum remobilization. Field observations suggest that both types of depositional evaporites were likely sourced from the recycling of adjacent salt structures. Precipitation of lacustro-sebkhaic evaporites may have been triggered by meteoric waters enriched in dissolved sulfate after the chemical dissolution of outcropping evaporites. Gypsarenite deposits can be explained by mechanical dismantling of nearby evaporite structures. Evaporitic deposits were subsequently involved in active salt tectonics. During periods of quiescent diapirism, thick sebkhaic deposits were also deposited in secondary minibasins located on former salt domes. During periods of diapiric growth, linked to regional compressive tectonics, these deposits were then locally deformed and can show strong flowage textures. When rising diapiric evaporites reached the surface, it was also able to mechanically spread out within the minibasins, forming salt glaciers. In this case, if depositional evaporites were overlying the extruded diapir, both diapiric and depositional evaporites were incorporated in salt tectonic structures. Ongoing chemical analysis should help us to precise more accurately the different sources and the dynamics of these multigeneration evaporites.

  12. Surficial deposits in the Bear Lake Basin

    USGS Publications Warehouse

    Reheis, Marith C.; Laabs, Benjamin J.C.; Forester, Richard M.; McGeehin, John P.; Kaufman, Darrell S.; Bright, Jordon

    2005-01-01

    Mapping and dating of surficial deposits in the Bear Lake drainage basin were undertaken to provide a geologic context for interpretation of cores taken from deposits beneath Bear Lake, which sometimes receives water and sediment from the glaciated Bear River and sometimes only from the small drainage basin of Bear Lake itself. Analyses of core sediments by others are directed at (1) constructing a high-resolution climate record for the Bear Lake area during the late Pleistocene and Holocene, and (2) investigating the sources and weathering history of sediments in the drainage basin. Surficial deposits in the upper Bear River and Bear Lake drainage basins are different in their overall compositions, although they do overlap. In the upper Bear River drainage, Quaternary deposits derived from glaciation of the Uinta Range contain abundant detritus weathered from Precambrian quartzite, whereas unglaciated tributaries downstream mainly contribute finer sediment weathered from much younger, more friable sedimentary rocks. In contrast, carbonate rocks capped by a carapace of Tertiary sediments dominate the Bear Lake drainage basin.

  13. Depositional history and seismic stratigraphy of Lower Cretaceous rocks in the National Petroleum Reserve in Alaska and adjacent areas

    SciTech Connect

    Molenaar, C.M.

    1989-01-01

    Lower Cretaceous rocks, which are widespread throughout the National Petroleum Reserve in Alaska (NPRA) and adjacent areas north of the Brooks Range, make up the major part of the thick sedimentary fill of the Colville basin. Much seismic and well information obtained since 1974 has aided considerably in understanding these rocks. These data include about 20,000 km of seismic lines, covering much of the NPRA with a grid spacing of 10-20 km, and 28 exploratory wells that bring the total to more than 50 wells in and adjacent to the NPRA. The purpose of this chapter is to interpret the depositional history of Lower Cretaceous rocks in the NPRA and adjacent areas on the basis of the latest seismic and well data and well data and on information from outcrops in the southern part of the Colville basin. The basin geometry and depositional history described in earlier reports are repeated here in the context of the overall Lower Cretaceous depositional history. Well data (including paleontology) and seismic data are used almost exclusively to interpret relations in the northern foothills and coastal plain areas. Surface data and some well data are used in the southern parts of the northern foothills, and surface data are used exclusively to interpret the depositional history in the southern foothills and Brooks Range. The quality of seismic data is fair to good in most of the coastal plain, where the structure is simple. In the northern foothills, tracing seismic reflections is more difficult, especially in the shallower part of the section because of structural complications in the thrust-faulted anticlines. The quality of seismic data across the structurally complex southern foothills area is inadequate to correlate stratigraphic units of the outcrop area of the southern foothills with subsurface units to the north.

  14. Mineral dust deposition in Western Mediterranean basin

    NASA Astrophysics Data System (ADS)

    Vincent, Julie; Laurent, Benoit; Bergmatti, Gilles; Losno, Rémi; Bon Nguyen, Elisabeth; Chevaillier, Servanne; Roulet, Pierre; Sauvage, Stéphane; Coddeville, Patrice; Ouboulmane, Noura; Siour, Guillaume; Tovar Sanchez, Antonio; Massanet, Ana; Morales Baquero, Rafael; Di Sarra, Giogio; Sferlazzo, Damiano; Dulac, François; Fornier, Michel; Coursier, Cyril

    2014-05-01

    North African deserts are the world's largest sources of atmospheric mineral dust produced by aeolian erosion. Saharan dust is frequently transported toward Europe over the Mediterranean basin. When deposited in oceanic areas, mineral dust can constitute a key input of nutrients bioavailable for the oceanic biosphere. For instance, Saharan dust deposited in the in the Mediterranean Sea can be a significant source of nutrient like Fe, P and N during summer and autumn. Our objective is to study the deposition Saharan mineral dust in the western Mediterranean basin and to improve how deposition processes are parameterized in 3D regional models. To quantify the deposition flux of Saharan dust in the western Mediterranean region a specific collector (CARAGA) to sample automatically the insoluble atmospheric particle deposition was developed (LISA-ICARE) and a network of CARAGA collectors have been set up. Since 2011, eight CARAGA are then deployed in Frioul, Casset, Montandon and Ersa in France, Mallorca and Granada in Spain, Lampedusa in Italia, and Medenine in Tunisia, along a South-North gradient of almost 2000km from the North African coast to the South of Europe. We observe 10 well identified dust Saharan deposition events at Lampedusa and 6 at Mallorca for a 1-yr sampling period. These dust events are sporadic and the South-North gradient of deposition intensity and frequency is observed (the highest dust mass sampled at the stations are : 2,66 g.m-2 at Lampedusa ; 0,54 g.m-2 at Majorque ; 0,33 g.m-2 at Frioul ; 0,16 g.m-2 at Casset). The ability of the CHIMERE model to reproduce the deposition measurements is tested. The mineral dust plumes simulated over the western Mediterranean basin are also compared to satellite observations (OMI, MODIS) and in-situ measurements performed during the ChArMEx campaign and in the AERONET stations.

  15. Controls on bacterial gas accumulations in thick Tertiary coal beds and adjacent channel sandstones, Powder River basin, Wyoming and Montana

    SciTech Connect

    Rice, D.D.; Flores, R.M. )

    1991-03-01

    Coal beds, as much as 250 ft thick, and adjacent sandstones in the Paleocene Tongue River Member of the Fort Union Formation are reservoirs for coal-derived natural gas in the Powder River basin. The discontinuous coal beds were deposited in raised, ombrotrophic peat bogs about 3 mi{sup 2} in size, adjoining networks of fluvial channels infilled by sand. Coal-bed thickness was controlled by basin subsidence and depositional environments. The average maceral composition of the coals is 88% huminite (vitrinite), 5% liptinite, and 7% inertinite. The coals vary in rank from subbituminous C to A (R{sub o} values of 0.4 to 0.5%). Although the coals are relatively low rank, they display fracture systems. Natural gas desorbed and produced from the coal beds and adjacent sandstones is composed mainly of methane with lesser amount of Co{sub 2} ({lt}10%). The methane is isotopically light and enriched in deuterium. The gases are interpreted to be generated by bacterial processes and the fermentation pathway, prior to the main phase of thermogenic methane generation by devolatilization. Large amounts of bicarbonate water generated during early stages of coalification will have to be removed from the fracture porosity in the coal beds before desorption and commercial gas production can take place. Desorbed amounts of methane-rich, bacterial gas in the Powder River basin are relatively low ({lt}60 Scf/ton) compared to amounts of thermogenic coal-bed gases (hundreds of Scf/ton) from other Rocky Mountain basins. However, the total coal-bed gas resource in both the coal beds and the adjacent sandstones is considered to be large (as much as 40 Tcf) because of the vast coal resources (as much as 1.3 trillion tons).

  16. Water resources of the Waccasassa River Basin and adjacent areas, Florida

    USGS Publications Warehouse

    Taylor, G.F.; Snell, L.J.

    1978-01-01

    This map report was prepared in cooperation with the Southwest Florida Water Management District which, with the Waccasassa River Basin Board, had jurisdiction over waters within the Waccasassa River basin, the coastal areas adjacent to the basin, and other adjacent areas outside the basin. New water management district boundaries, effective January 1977, place most of the Waccasassa River basin in the Suwannee River Water Management District. The purpose of the report is to provide water information for consideration in land-use and water development which is accelerating, especially in the northeastern part of the study area. It is based largely on existing data in the relatively undeveloped area. Of the total area included in the topographic drainage basin for the Waccasassa River about 72 percent is in Levy County, 18 percent in Alachua County, 9 percent in Gilchrist County, and 1 percent in Marion County. The elongated north-south drainage basin is approximately 50 mi in length, averages 13 mi in width, and lies between the Suwannee River, the St. Johns River, and the Withlacoochee River basins. (Woodard-USGS)

  17. Radiolarian paleo-oceanographic studies of Humboldt basin and adjacent areas

    SciTech Connect

    Nelson, C.O.

    1986-04-01

    Miocene-Pliocene samples from land-based sections along an east-west transect of the Humboldt basin were analyzed for microfossil content. The microfossil populations reflect the gradual infilling and shoaling of the basin. Radiolarian fauna indicate that initial deposition occurred in a basin open to deep marine waters. The shelfal characteristics of the radiolarian populations increase through time in a west-east direction. Fauna appear to be sourced from cooler waters of the North Pacific and deep Central Pacific.

  18. Mesozoic tectonics and paleogeography of the western U. S. and the adjacent Pacific basin

    SciTech Connect

    Dilek, Y. )

    1990-06-01

    Recent geological, geochemical, and geochronological information from Jurassic and older ophiolite complexes and arc rocks in northern California provides new interpretations for Mesozoic tectonics of the western US and the adjacent Pacific basin. This information is discussed in conjunction with the Mesozoic tectonics and paleogeography of the western United States and the Pacific Ocean.

  19. Correlations between the Lomonosov Ridge, Marvin Spur and adjacent basins of the Arctic Ocean based on seismic data

    NASA Astrophysics Data System (ADS)

    Langinen, A. E.; Lebedeva-Ivanova, N. N.; Gee, D. G.; Zamansky, Yu. Ya.

    2009-07-01

    Seismic profiles across the Lomonosov Ridge, Marvin Spur and adjacent basins, acquired near the North Pole by the drifting ice-station NP-28, provide a reflection image of the upper parts of the Ridge that is readily correlatable with those acquired by the Alfred Wegner Institute closer to the Siberian margin. A prominent flat-lying composite reflection package is seen in most parts of the Ridge at a few hundred meters below the sea bottom. Underlying reflections are variable in intensity and also in dip. The base of this reflection package is often accompanied by a sharp increase in P-velocity and defines a major angular discontinuity, referred to here as the Lomonosov Unconformity. The Arctic Coring Expedition (ACEX) cored the first c. 430 m section on the Lomonosov Ridge near the North Pole, in 2004 defining the deeper water character of the Neogene and the shallower water Paleogene sediments. These boreholes penetrated the composite reflection package towards the base of the hole and identified sediments (our Unit III) of late Paleocene and early Eocene age. Campanian beds at the very base of the hole were thought to be representative of the units below the Lomonosov Unconformity, but the P-velocity data suggest that this is unlikely. Correlation of the lithologies along the top of the Lomonosov Ridge and to the Marvin Spur indicates that the Marvin Spur is a sliver of continental crust closely related to, and rifted off the Ridge. This narrow (50 km wide) linear basement high can be followed into, beneath and across the Makarov Basin, supporting the interpretation that this Basin is partly resting on thinned continental crust. In the Makarov Basin, the Paleogene succession is much thicker than on the Ridge. Thus, the condensed, shallow water succession (with hiati) was deposited on the Ridge during rapid Eocene to Miocene subsidence of the Basin. In the Amundsen Basin, adjacent to the Lomonosov Ridge, the sedimentary successions thicken towards the Canadian

  20. Tectonic origin of Lower Mesozoic regional unconformities: Southern Colorado Plateau and adjacent Basin and Range

    SciTech Connect

    Marzolf, J.E. )

    1990-05-01

    Palinspastic restoration of Basin and Range structural blocks to early Mesozoic positions relative to the Colorado Plateau permits correlation of lower Mesozoic regional unconformities of the Colorado Plateau across the southern Basin and Range. These unconformities correlate with tectonic reconfiguration of sedimentary basins in which enclosed depositional sequences were deposited. Lesser recognized intraformational unconformities are related to relative sea level change. The Tr-1 unconformity developed on subaerially exposed, karsted, and deeply incised Leonardian carbonates. The overlying Lower Triassic Moenkopi Formation and equivalent strata display a narrow, north-south aligned, passive-margin-type architecture subdivided by Smithian and Spathian intraformational unconformities into three depositional sequences. From basinal to inner shelf facies, Tr-1 truncates folds in Permian rocks. Initial deposition of the lowest sequence began with sea level at the base of the continental slope. Basal conglomerates of the Upper Triassic Chinle Formation were deposited in northward-trending paleovalleys incised within and parallel to the Early Triassic shelf. Distribution of fluvial deposition, orientation of paleovalleys, paleocurrent indicators, and provenance indicate change from the passive-margin-bordered Early Triassic basin to an offshore active-margin basin. Continental and marine facies suggest two depositional sequences separated by an early Norian type 2( ) sequence boundary. The J-O unconformity at the base of the Lower Jurassic Glen Canyon Group marks a major change in tectonic setting of western North America as evidenced by (1) progressive southwestward downcutting of the unconformity to deformed Paleozoic rocks and Precambrian basement, (2) coincidence in time and space with Late Triassic to Early Jurassic thrust faults, and (3) initiation of calcalkaline volcanism.

  1. Hydrogeologic framework of sedimentary deposits in six structural basins, Yakima River basin, Washington

    USGS Publications Warehouse

    Jones, M.A.; Vaccaro, J.J.; Watkins, A.M.

    2006-01-01

    The hydrogeologic framework was delineated for the ground-water flow system of the sedimentary deposits in six structural basins in the Yakima River Basin, Washington. The six basins delineated, from north to south are: Roslyn, Kittitas, Selah, Yakima, Toppenish, and Benton. Extent and thicknesses of the hydrogeologic units and total basin sediment thickness were mapped for each basin. Interpretations were based on information from about 4,700 well records using geochemical, geophysical, geologist's or driller's logs, and from the surficial geology and previously constructed maps and well interpretations. The sedimentary deposits were thickest in the Kittitas Basin reaching a depth of greater than 2,000 ft, followed by successively thinner sedimentary deposits in the Selah basin with about 1,900 ft, Yakima Basin with about 1,800 ft, Toppenish Basin with about 1,200 ft, Benton basin with about 870 ft and Roslyn Basin with about 700 ft.

  2. Geologic appraisal of Paradox basin salt deposits for water emplacement

    USGS Publications Warehouse

    Hite, R.J.; Lohman, Stanley William

    1973-01-01

    Thick salt deposits of Middle Pennsylvanian age are present in an area of 12,000 square miles in the Paradox basin of southeast Utah and southwest Colorado. The deposits are in the Paradox Member of the Hermosa Formation. The greatest thickness of this evaporite sequence is in a troughlike depression adjacent to the Uncompahgre uplift on the northeast side of the basin. The salt deposits consist of a cyclical sequence of thick halite units separated by thin units of black shale, dolomite, and anhydrite. Many halite units are several hundred feet thick and locally contain economically valuable potash deposits. Over much of the Paradox basin the salt deposits occur at depths of more than 5,000 feet. Only in a series of salt anticlines located along the northeastern side of the basin do the salt deposits rise to relatively shallow depths. The salt anticlines can be divided geographically and structurally into five major systems. Each system consists of a long undulating welt of thickened salt over which younger rocks are arched in anticlinal form. Locally there are areas along the axes of the anticlines where the Paradox Member was never covered by younger sediments. This allowed large-scale migration of Paradox strata toward and up through these holes in the sediment cover forming diapiric anticlines. The central or salt-bearing cores of tthe anticlines range in thickness from about 2,500 to 14,000 feet. Structure in the central core of the salt anticlines is the result of both regional-compression and flowage of the Paradox Member into the anticlines from adjacent synclines. Structure in the central cores of the salt anticlines ranges from relatively undeformed beds to complexly folded and faulted masses, in which stratigraphic continuity is undemonstrable. The presence of thick cap rock .over many of the salt anticlines is evidence of removal of large volumes of halite by groundwater. Available geologic and hydrologic information suggests that this is a relatively

  3. The sedimentary and crustal velocity structure of Makarov Basin and adjacent Alpha Ridge

    NASA Astrophysics Data System (ADS)

    Evangelatos, John; Funck, Thomas; Mosher, David C.

    2017-01-01

    This study examines the velocity structure of Makarov Basin and the adjacent Alpha Ridge to determine the tectonic origins of these features and link them to the larger Amerasia Basin. Seismic data from sonobuoys distributed along a 650 km-long line extending from Alpha Ridge and across Makarov Basin to the Lomonosov Ridge were analyzed for this purpose. Forward modelling of traveltimes, supported by coincident multi-channel seismic reflection and shipborne gravity data, were used to determine the P-wave velocity structure along the line. The sedimentary cover averages 0.5 km-thick on Alpha Ridge and 1.9 km-thick in Makarov Basin, but reaches up to 5 km-thick at the base of Lomonosov Ridge. Velocities in the sedimentary section range from 1.6 to 4.3 km s- 1. As suggested by relatively high velocities, interbedded volcaniclastic or volcanic rock may occur in the deep sedimentary section. The shallow basement of Alpha Ridge (3.3 to 3.6 km s- 1) is characterized by semi-continuous high amplitude reflections and is interpreted as volcanic rock possibly intercalated with sedimentary rock. Velocities do not vary significantly in the upper and mid-crustal layers between Alpha Ridge and Makarov Basin. Total crustal thickness decreases from 27 km beneath Alpha Ridge to 5 km-thick in Makarov Basin then thickens to > 20 km over a short distance as part of Lomonosov Ridge. The crustal structure of Alpha Ridge is consistent with previous studies suggesting that the Alpha-Mendeleev ridge complex is part of a large igneous province (LIP) with thick igneous crust. The lack of change in crustal velocities between Alpha Ridge and Makarov Basin suggests that the basin, at least partly, either formed during or was influenced by LIP-related magmatism. The rapid transition of crustal thicknesses from Makarov Basin to Lomonosov Ridge supports the interpretation that this section of the ridge is a transform margin.

  4. Gulf of California analogue for origin of Late Paleozoic ocean basins adjacent to western North America

    SciTech Connect

    Murchey, B.L. )

    1993-04-01

    Ocean crust accreted to the western margin of North America following the Late Devonian to earliest Missippian Antler orogeny is not older than Devonian. Therefore, ocean crust all along the margin of western North America may have been very young following the Antler event. This situation can be compared to the present-day margin of North America which lies adjacent to young ocean crust as a result of the subduction of the Farallon plate and arrival of the East Pacific spreading ridge. Syn- and post-Antler rifting that occurred along the North American margin may well be analogous to the formation of the Gulf of California by the propagation of the East Pacific spreading ridge. Black-arc rifting associated with the subduction of very old ocean crust seems a less likely mechanism for the early stages of ocean basin formation along the late Paleozoic margin of western North America because of the apparent absence of old ocean crust to the west of the arc terranes. The eastern Pacific basins were as long-lived as any truly oceanic basins and may have constituted, by the earliest Permian, a single wedge-shaped basin separated from the western Pacific by rifted fragments of North American arc-terranes. In the Permian, the rifted arcs were once again sites of active magmatism and the eastern Pacific basins began to close, from south (Golconda terrane) to north. Final closure of the northernmost eastern Pacific basin (Angayucham in Alaska) did not occur until the Jurassic.

  5. 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

  6. Quantifying Channelized Submarine Depositional Systems From Bed to Basin Scale

    DTIC Science & Technology

    2004-09-01

    Biostratigraphic appli- cation and ecology of agglutinated foraminifera in Gulf of Mexico Basin Cenozoic exploration. GCAGS Transactions, 52:65-76, 2002. S.Q...Using seismic data from the Fisk Basin, Gulf of Mexico , I find that, during periods of broadly distributed, sheet-like deposition, equilibrium time is on...time scales for channel/levee com- plexes and sheet-like deposits: Fisk Basin, Gulf of Mexico 97 3.1 Introduction - Channel/levee complexes and

  7. Selected ground-water information for the Pasco basin and adjacent areas, Washington, 1986-1989

    USGS Publications Warehouse

    Drost, B.W.; Schurr, K.M.; Lum, W. E.

    1989-01-01

    The U.S. Geological Survey, in cooperation with the United States Department of Energy, conducted a study of the Pasco basin and adjacent areas, Washington, in support of the Basalt Waste Isolation Project at the Hanford site, Washington. The purpose of the study was to develop a data set that would help define the groundwater-flow system of the Pasco Basin. This report contains the basic data, without interpretation, that were collected from the start of the project in February 1986 through January 1989. Information presented is from the U.S. Bureau of Reclamation, State of Washington Department of Ecology , US Army Corps of Engineers, Kennewick Irrigation District, and the Survey, and consists of well location and construction data, records of water levels in the wells, and aquifer designations for each well. The aquifer designation represents the geohydrologic unit to which the well is reported to be open. (USGS)

  8. Sea-floor drainage features of Cascadia Basin and the adjacent continental slope, northeast Pacific Ocean

    USGS Publications Warehouse

    Hampton, M.A.; Karl, Herman A.; Kenyon, Neil H.

    1989-01-01

    Sea-floor drainage features of Cascadia Basin and the adjacent continental slope include canyons, primary fan valleys, deep-sea valleys, and remnant valley segments. Long-range sidescan sonographs and associated seismic-reflection profiles indicate that the canyons may originate along a mid-slope escarpment and grow upslope by mass wasting and downslope by valley erosion or aggradation. Most canyons are partly filled with sediment, and Quillayute Canyon is almost completely filled. Under normal growth conditions, the larger canyons connect with primary fan valleys or deep-sea valleys in Cascadia Basin, but development of accretionary ridges blocks or re-routes most canyons, forcing abandonment of the associated valleys in the basin. Astoria Fan has a primary fan valley that connects with Astoria Canyon at the fan apex. The fan valley is bordered by parallel levees on the upper fan but becomes obscure on the lower fan, where a few valley segments appear on the sonographs. Apparently, Nitinat Fan does not presently have a primary fan valley; none of the numerous valleys on the fan connect with a canyon. The Willapa-Cascadia-Vancouver-Juan de Fuca deep-sea valley system bypasses the submarine fans and includes deeply incised valleys to broad shallow swales, as well as within-valley terraces and hanging-valley confluences. ?? 1989.

  9. 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.

  10. Thicknesses of and Primary Ejecta Fractions in Basin Ejecta Deposits

    NASA Technical Reports Server (NTRS)

    Haskin, Larry A.; McKinnon, William B.

    2003-01-01

    We have developed a model for production of ba-sin ejecta deposits to address provenances of materials collected at the Apollo and Luna landing sites and for consideration in interpreting remote sensing data.

  11. Thicknesses of and Primary Ejecta Fractions in Basin Ejecta Deposits

    NASA Technical Reports Server (NTRS)

    Haskin, Larry A.; McKinnon, William B.

    2003-01-01

    We have developed a model for production of basin ejecta deposits to address provenances of materials collected at the Apollo and Luna landing sites and for consideration in interpreting remote sensing data.

  12. Geomorphology of crater and basin deposits - Emplacement of the Fra Mauro formation

    NASA Technical Reports Server (NTRS)

    Morrison, R. H.; Oberbeck, V. R.

    1975-01-01

    Characteristics of continuous deposits near lunar craters larger than about 1 km wide are considered, and it is concluded that (1) concentric dunes, radial ridges, and braided lineations result from deposition of the collision products of ejecta from adjacent pairs of similarly oriented secondary-crater chains and are, therefore, concentrations of secondary-crater ejecta; (2) intracrater ridges are produced within preexisting craters surrounding a fresh primary crater by ricocheting and focusing of secondary-crater ejecta from the preexisting craters' walls; and (3) secondary cratering has produced many of the structures of the continuous deposits of relatively small lunar craters and is the dominant process for emplacement of most of the radial facies of the continuous deposits of large lunar craters and basins. The percentages of Imbrium ejecta in deposits and the nature of Imbrium sculpturing are investigated.

  13. Cleanup Verification Package for the 118-F-8:4 Fuel Storage Basin West Side Adjacent and Side Slope Soils

    SciTech Connect

    L. D. Habel

    2008-03-18

    This cleanup verification package documents completion of remedial action, sampling activities, and compliance with cleanup criteria for the 118-F-8:4 Fuel Storage Basin West Side Adjacent and Side Slope Soils. The rectangular-shaped concrete basin on the south side of the 105-F Reactor building served as an underwater collection, storage, and transfer facility for irradiated fuel elements discharged from the reactor.

  14. Impact of structural and autocyclic basin-floor topography on the depositional evolution of the deep-water Valparaiso forearc basin, central Chile

    USGS Publications Warehouse

    Laursen, J.; Normark, W.R.

    2003-01-01

    The Valparaiso Basin constitutes a unique and prominent deep-water forearc basin underlying a 40-km by 60-km mid-slope terrace at 2.5-km water depth on the central Chile margin. Seismic-reflection data, collected as part of the CONDOR investigation, image a 3-3.5-km thick sediment succession that fills a smoothly sagged, margin-parallel, elongated trough at the base of the upper slope. In response to underthrusting of the Juan Ferna??ndez Ridge on the Nazca plate, the basin fill is increasingly deformed in the seaward direction above seaward-vergent outer forearc compressional highs. Syn-depositional growth of a large, margin-parallel monoclinal high in conjunction with sagging of the inner trough of the basin created stratal geometries similar to those observed in forearc basins bordered by large accretionary prisms. Margin-parallel compressional ridges diverted turbidity currents along the basin axis and exerted a direct control on sediment depositional processes. As structural depressions became buried, transverse input from point sources on the adjacent upper slope formed complex fan systems with sediment waves characterising the overbank environment, common on many Pleistocene turbidite systems. Mass failure as a result of local topographic inversion formed a prominent mass-flow deposit, and ultimately resulted in canyon formation and hence a new focused point source feeding the basin. The Valparaiso Basin is presently filled to the spill point of the outer forearc highs, causing headward erosion of incipient canyons into the basin fill and allowing bypass of sediment to the Chile Trench. Age estimates that are constrained by subduction-related syn-depositional deformation of the upper 700-800m of the basin fill suggest that glacio-eustatic sea-level lowstands, in conjunction with accelerated denudation rates, within the past 350 ka may have contributed to the increase in simultaneously active point sources along the upper slope as well as an increased

  15. Deposit model for closed-basin potash-bearing brines

    USGS Publications Warehouse

    Orris, Greta J.

    2011-01-01

    Closed-basin potash-bearing brines are one of the types of potash deposits that are a source of potash production within the United States, as well as other countries. Though these deposits are of highly variable size, they are important sources of potash on a regional basis. In addition, these deposits have a high potential of co- and by-product production of one or more commodities such as lithium, boron, magnesium, and others.

  16. Depositional and thermal history of Lower Triassic rocks in southwestern Montana and adjacent parts of Wyoming and Idaho

    SciTech Connect

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

    1989-09-01

    Forty-two stratigraphic sections in Montana and adjacent parts of Wyoming and Idaho provide the framework for a conodont biostratigraphic and carbonate sedimentologic analysis of Lower Triassic marine rocks. From oldest to youngest, these units are the Dinwoody, Woodside (Red Peak to the east), and Thaynes Formations. The Dinwoody disconformably overlies Upper Permian rocks with little or no physical evidence of a 1 to 6-m.y. hiatus. The initial Triassic transgression was extensive and geologically instantaneous across the study area, and it resulted in deposition of interbedded calcareous mudstone, siltstone, and limestone. The Dinwoody varies in thickness from zero on the northeast to greater than 270 m in the southwest. Maximum thicknesses of Woodside red beds and Thaynes carbonates and siltstones are 244 and 400 m, respectively. Post-Triassic erosion progressively truncated the Thaynes, Woodside, and Dinwoody from north to south across the region. The western margin of the Triassic seaway in the study area is obscured by erosion, structural complexities, igneous activity, and younger sedimentary deposits. The sparse and scattered exposures that remain provide an intriguing mosaic of depositional environments that range from shallow marine to basinal and represent most of Early Triassic time. Lower Triassic rocks produce gas in the Wyoming-Idaho thrust belt, and similar potential may exist in Montana. Conodonts recovered from surface exposures are thermally unaltered except in close proximity to intrusive bodies and within the Medicine Lodge thrust system. This establishes that subsurface units in much of the study area are within the temperature regime for dry gas generation.

  17. Aquifer systems in the Great Basin region of Nevada, Utah, and adjacent states; a study plan

    USGS Publications Warehouse

    Harrill, James R.; Welch, A.H.; Prudic, D.E.; Thomas, J.M.; Carman, R.L.; Plume, R.W.; Gates, J.S.; Mason, J.L.

    1983-01-01

    The Great Basin Regional Aquifer Study includes about 140,000 square miles in parts of Nevada, Utah, California, Idaho, Oregon , and Arizona within which 240 hydrographic areas occupy structural depressions formed primarily by basin-and-range faulting. The principal aquifers are in basin-fill deposits; however, significant carbonate-rock aquifers underlie much of eastern Nevada and western Utah. In October 1980, the U.S. Geological Survey started a 4-year study to: (1) describe the ground-water systems, (2) analyze the changes that have led to the systems ' present conditions, (3) tie the results of this and previous studies together in a regional analysis, and (4) provide means by which effects of future ground-water development can be estimated. A plan of work is presented that describes the general approach to be taken. It defines the major tasks necessary to meet objectives and defines constraints on the scope of work. The approach has been influenced by the diverse nature of ground water flow systems and the large number of basins. A detailed appraisal of 240 individual areas would require more resources than are available. Consequently, the general approach is to study selected ' typical ' areas and key hydrologic processes. Effort during the first three years will be directed toward describing the regional hydrology, conducting detailed studies of ' type ' areas and studying selected hydrologic processes. Effort during the final year will be directed toward developing a regional analysis of results. Special studies will include evaluation of regional geochemistry , regional hydrogeology, recharge, ground-water discharge, and use of remote sensing. Areas to be studied using ground-water flow models include the regional carbonate-rock province in eastern Nevada and western Utah, six valleys--Las Vegas, Carson, Paradise, Dixie, Smith Creek, and Stagecoach--Nevada, plus Jordan Valley, the Millford area, and Tule Valley in Utah. The results will be presented in a

  18. Large-rock avalanche deposits, eastern Basin and Range, Utah: Emplacement, diagenesis, and economic potential

    SciTech Connect

    Morris, T.H.; Hebertson, G.F.

    1996-07-01

    Large-rock avalanche deposits are a common component of the basin fill within the extensional tectonic terrain of the Basin and Range; these deposits recently have been interpreted to host oil and gas within the Railroad Valley area of eastern Nevada. Large blocks of brecciated bedrock are a primary component of these avalanche deposits and are potentially excellent oil and gas reservoirs. Our work provides further insight into the emplacement and economic potential of these deposits. Exposed large-rock avalanche deposits of the Miocene Oak City Formation on the western margin of the Canyon Range, Utah, contain coherent breccia blocks up to 3.5 km long, 1 km wide, and 200 m thick. These deposits were derived from the near-vertical dipping bed rock of the adjacent Canyon Range and now are exposed as much as 5.5 km from the range front within the Sevier Desert basin. Emplacement was relatively rapid, as indicated by three well-developed breccia facies within the carbonate breccia blocks. Stratigraphically, from the base the facies include (1) matrix-rich breccia, (2) jigsaw breccia, and (3) crackle breccia. The deposits were cut and segmented by a series of syn-depositional normal faults that developed during late Miocene and post-Miocene extension. Primary porosity was reduced by cement soon after burial. Cathodoluminescence cement patterns indicate that initially the basinward breccia blocks were more deeply buried relative to the water table than the breccia blocks proximal to the Canyon Range. After initial cementation, the basinward blocks were uplifted relative to the water table. Secondary porosity approaches 8% in the carbonate blocks and is greater than 14% within the jigsaw breccia. The size and porosity of these breccia blocks indicate their potential as reservoir targets.

  19. Hydrology of the coastal springs ground-water basin and adjacent parts of Pasco, Hernando, and Citrus Counties, Florida

    USGS Publications Warehouse

    Knochenmus, Lari A.; Yobbi, Dann K.

    2001-01-01

    The coastal springs in Pasco, Hernando, and Citrus Counties, Florida consist of three first-order magnitude springs and numerous smaller springs, which are points of substantial ground-water discharge from the Upper Floridan aquifer. Spring flow is proportional to the water-level altitude in the aquifer and is affected primarily by the magnitude and timing of rainfall. Ground-water levels in 206 Upper Floridan aquifer wells, and surface-water stage, flow, and specific conductance of water from springs at 10 gaging stations were measured to define the hydrologic variability (temporally and spatially) in the Coastal Springs Ground-Water Basin and adjacent parts of Pasco, Hernando, and Citrus Counties. Rainfall at 46 stations and ground-water withdrawals for three counties, were used to calculate water budgets, to evaluate long-term changes in hydrologic conditions, and to evaluate relations among the hydrologic components. Predictive equations to estimate daily spring flow were developed for eight gaging stations using regression techniques. Regression techniques included ordinary least squares and multiple linear regression techniques. The predictive equations indicate that ground-water levels in the Upper Floridan aquifer are directly related to spring flow. At tidally affected gaging stations, spring flow is inversely related to spring-pool altitude. The springs have similar seasonal flow patterns throughout the area. Water-budget analysis provided insight into the relative importance of the hydrologic components expected to influence spring flow. Four water budgets were constructed for small ground-water basins that form the Coastal Springs Ground-Water Basin. Rainfall averaged 55 inches per year and was the only source of inflow to the Basin. The pathways for outflow were evapotranspiration (34 inches per year), runoff by spring flow (8 inches per year), ground-water outflow from upward leakage (11 inches per year), and ground-water withdrawal (2 inches per year

  20. Geology and deposits of the lunar Nectaris basin

    NASA Technical Reports Server (NTRS)

    Spudis, P. D.; Hawke, B. R.; Lucey, P. G.

    1989-01-01

    The geology and composition of Nectaris basin deposits have been investigated in order to provide information on the lunar basin-forming process and the regional geologic setting of the Apollo 16 landing site. Several outcrops of nearly pure anorthosite were noted in locations such as the walls of Kant crater, an inner ring of the basin, and the crater Bohnenberger F. The results suggest that the impact can be modeled as a proportional-growth crater, and that the Nectaris excavation cavity was about 470 km in diameter and as deep as 55 km.

  1. The Alegre Lineament and its role over the tectonic evolution of the Campos Basin and adjacent continental margin, Southeastern Brazil

    NASA Astrophysics Data System (ADS)

    Calegari, Salomão Silva; Neves, Mirna Aparecida; Guadagnin, Felipe; França, George Sand; Vincentelli, Maria Gabriela Castillo

    2016-08-01

    The structural framework and tectonic evolution of the sedimentary basins along the eastern margin of the South American continent are closely associated with the tectonic framework and crustal heterogeneities inherited from the Precambrian basement. However, the role of NW-SE and NNW-SSE structures observed at the outcropping basement in Southeastern Brazil and its impact over the development of those basins have not been closely investigated. In the continental region adjacent to the Campos Basin, we described a geological feature with NNW-SSE orientation, named in this paper as the Alegre Fracture Zone (AFZ), which is observed in the onshore basement and can be projected to the offshore basin. The main goal of this work was to study this structural lineament and its influence on the tectonic evolution of the central portion of the Campos Basin and adjacent mainland. The onshore area was investigated through remote sensing data joint with field observations, and the offshore area was studied through the interpretation of 2-D seismic data calibrated by geophysical well logs. We concluded that the AFZ occurs in both onshore and offshore as a brittle deformation zone formed by multiple sets of fractures that originated in the Cambrian and were reactivated mainly as normal faults during the rift phase and in the Cenozoic. In the Campos Basin, the AFZ delimitates the western side of the Corvina-Parati Low, composing a complex fault system with the NE-SW faults and the NW-SE transfer faults.

  2. Depositional systems and petroleum potential, Mesaverde Formation southeastern Wind River basin, Wyoming

    SciTech Connect

    Hippe, D.J.; Needham, D.W.; Ethridge, F.G.

    1986-08-01

    Depositional environments and systems of the Wind River basin Mesaverde Formation were interpreted from an analysis of outcrops along the Casper arch and Rattlesnake Hills anticline and cores and wireline logs from the adjacent subsurface. The Fales Sandstone and Parkman Sandstone/unnamed middle member are deposits of eastward progradational, wave-dominated strand-plain and deltaic complexes. Basal portions of the Fales Sandstone and the Parkman Sandstone are composed of a thickening- and coarsening-upward sandstone sequence whose facies represent storm-dominated inner-shelf and wave-dominated shore-zone environments. Facies sequences in the upper Fales Sandstone interval and the unnamed middle member are interpreted as deposits of lower coastal plain (marshes, bay fills, distributary channels, and crevasse splays) and upper coastal plain (alluvial channels, crevasse splays and fine-grained flood basin) sequences. The Teapot Sandstone is interpreted as an alluvial deposit. Analysis of facies sequences in the Teapot suggests a change in fluvial style, from braided-belt deposits along the southwest flank to meander-belt deposits along the northeast flank of the basin. These fluvial systems fed the Teapot deltas to the east. Stratigraphic plays for oil and gas include alluvial valley fills and point-bar deposits in the Teapot Sandstone, storm-dominated shelf sands in the upper Cody Shale and the Fales and Parkman Sandstones, and a transgressive barrier-bar sequence in the upper Fales Sandstone. Laterally continuous shore-zone sandstones may form combination traps where pinch-outs occur on structure.

  3. Depositional setting of the Jurassic Haynesville seismic sequence in the Apalachicola Basin, northeastern Gulf of Mexico

    SciTech Connect

    Dobson, L.M.; Buffler, R.T. )

    1990-05-01

    Seismic and well data from the northeastern Gulf of Mexico were used to define the seismic stratigraphy, geologic history, and depositional setting of the Jurassic (Kimmeridgian) Haynesville sequence in the Apalachicola basin. The data show that Haynesville clastic sedimentation updip was coeval with Haynesville carbonate deposition downdip. The regional Jurassic seismic stratigraphic framework includes, in ascending order, the Louann Salt Norphlet-Smackover, Haynesville, and Cotton Valley sequences. In the vicinity of Destin dome, wells have penetrated Haynesville sandstones, shales, and anhydrites. These clastics correlate with low amplitude, low-continuity reflections that characterize the Haynesville over a broad area updip. Similar reflections within the overlying (Tithonian-earliest Berriasian) Cotton Valley clastic sequence make seismic definition of the top Haynesville sequence boundary difficult updip. As Haynesville clastics are replaced by carbonates downdip, a high amplitude reflection marks the top of the sequence. Haynesville carbonates conformably overlie (Oxfordian) Smackover carbonates in the basin center, and the lower sequence boundary cannot be defined where disrupted by growth faults associated with early movement of the (Callovian ) Louann Salt. Sigmoid clinoforms document Haynesville shelf margin development Seismic facies also include oblique clinoforms that prograde eastward into the basin from the Southern Platform and Middle Ground Arch. No wells penetrate this facies. Mapping of the seismic facies and correlation with well data suggest a depositional setting for the Haynesville sequence in which influx of terrigenous clastics probably derived from adjacent land areas to the north and northeast filled a broad lagoon behind a carbonate shelf margin.

  4. We are in need of sampling the sedimentary cover and bedrock in the Amerasia Basin. (Suggested site locations in the Makarov Basin, the Mendeleev and Lomonosov ridges and adjacent areas.)

    NASA Astrophysics Data System (ADS)

    Lebedeva-Ivanova, N. N.

    2010-12-01

    The Amerasia Basin has a complex origin; alone, the geophysical data can support very different hypotheses. For understanding the tectonic evolution of the Basin and origin of the ridges and troughs it is important to collect geological samples. Based on analyzed seismic data (NP-28 and 26, HOTRAX, Arctic-2000 and TransArctic) over the Makarov Basin, the Mendeleev and Lomonosov ridges and adjacent areas, numbers of key drill sites are proposed. All proposed sites in combinations with other geophysical research of the area are fit well with most of the Site Survey Data Requirements (IODP) for a drilling site. Bedrock samples from key locations are especially needed, with full video or photo documentation of the sampling for avoiding later debates about whether bedrock or ice-drift was collected. Due to close locations to a sea bottom, bedrock can be sampled by gravity piston-cores or shallow drilling. Full stratigraphic sections though the Cenozoic and older sedimentary successions are needed at other proposed key locations for understanding the tectonic evolution of the Amerasia Basin. The depositional environment of the key reflections related to Cenozoic shallow water environments, as recorded in the ACEX drillholes, needs to be investigated in other locations. We will then be able to define better the nature of particular morphological features and construct more reliable tectonic models of the Amerasia Basin, in general.

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

    USGS Publications Warehouse

    Clarke, S.H.

    1992-01-01

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

  6. Olivine Deposits Associated with Impact Basins and Craters on Mars

    NASA Astrophysics Data System (ADS)

    Ody, A.; Poulet, F.; Langevin, Y.; Gondet, B.; Bibring, J.; Carter, J.

    2011-12-01

    An analysis of the 1μm olivine spectral signature applied to the entire and final OMEGA dataset [1] shows numerous olivine-bearing deposits in the 3 main basins of Mars (Argyre, Isidis and Hellas). These signatures are among the strongest of Mars, which suggests compositions with higher iron content and/or larger grain size and/or larger abundance than the ones of widespread olivine-bearing deposits observed on large parts of the southern highlands [1]. A spectral modeling based on a radiative transfer model [2] indicates that their compositions are still close to the forsterite one with abundance in the range of [15,40%] and grain sizes of a few hundreds of μm. These deposits are exclusively localized on Noachian terrains. Distribution of these deposits around Argyre basin clearly takes the form of discontinuous patches of olivine-bearing rocks on the basin terrace, which strongly suggest that their formation is related to the basin formation event. Recent numerical simulations of basin formation show that impact that formed the Argyre basin could have excavated upper mantle materials and emplaced discontinuous patches of melted mantle on the basin terraces [3]. The observed olivine deposits in Argyre are thus interpreted as olivine-bearing material excavated from the upper mantle during the impact. Olivine deposits distribution around the Hellas basin is not as clear as for Argyre because of young resurfacing processes that strongly affected its region. Olivine deposits are fewer and mainly localized on the northern terrace of Hellas. Most of them are detected in crater ejecta, while a few similar to Argyre olivine discontinuous patches are also observed suggesting that a mantle origin as for Argyre is possible. Olivine has been detected by several datasets in the Nili Fossae region and in the south of Isidis basin. The spectral modeling of OMEGA spectra indicates an olivine abundance of about 40% and megacrysts of several millimeters for the region of Nili

  7. Sulfonylurea herbicides in an agricultural catchment basin and its adjacent wetland in the St. Lawrence River basin.

    PubMed

    de Lafontaine, Yves; Beauvais, Conrad; Cessna, Allan J; Gagnon, Pierre; Hudon, Christiane; Poissant, Laurier

    2014-05-01

    The use of sulfonylurea herbicides (SU) has increased greater than 100 times over the past 30 years in both Europe and North America. Applied at low rates, their presence, persistence and potential impacts on aquatic ecosystems remain poorly studied. During late-spring to early fall in 2009-2011, concentrations of 9 SU were assessed in two agricultural streams and their receiving wetland, an enlargement of the St. Lawrence River (Canada). Six SU in concentrations >LOQ (10 ng L(-1)) were detected in 10% or less of surface water samples. Rimsulfuron was detected each year, sulfosulfuron and nicosulfuron in two years and the others in one year only, suggesting that application of specific herbicides varied locally between years. Detection frequency and concentrations of SU were not significantly associated with total precipitation which occurred 1 to 5d before sampling. Concentrations and fate of SU differed among sites due to differences in stream dynamics and water quality characteristics. The persistence of SU in catchment basin streams reflected the dissipation effects associated with stream discharge. Maximum concentrations of some SU (223 and 148 ng L(-1)) were occasionally above the baseline level (100 ng L(-1)) for aquatic plant toxicity, implying potential toxic stress to flora in the streams. Substantially lower concentrations (max 55 ng L(-1)) of SU were noted at the downstream wetland site, likely as a result from dilution and mixing with St. Lawrence River water, and represent less toxicological risk to the wetland flora. Sporadic occurrence of SU at low concentrations in air and rain samples indicated that atmospheric deposition was not an important source of herbicides to the study area.

  8. Brine evolution and mineral deposition in hydrologically open evaporite basins

    USGS Publications Warehouse

    Sanford, W.E.; Wood, W.W.

    1991-01-01

    A lumped-parameter, solute mass-balance model is developed to define the role of water outflow from a well-mixed basin. A mass-balance model is analyzed with a geochemical model designed for waters with high ionic strengths. Two typical waters, seawater and a Na-HCO3 ground water, are analyzed to illustrate the control that the leakage ratio (or hydrologic openness of the basin) has on brine evolution and the suite and thicknesses of evaporite minerals deposited. The analysis suggests that brines evolve differently under different leakage conditions. -from Authors

  9. The Zeolite Deposit of Hekimhan in the Malatya Basin

    NASA Astrophysics Data System (ADS)

    Önal, Mehmet; Depci, Tolga; Ceylan, Cigdem; Kizilkaya, Nilgun

    2016-10-01

    Zeolite deposits in the Malatya Basin which is formed of the Yüksekova Group were investigated in the present study. The zeolites were occurred in the two layers: the lower zeolite layer and the upper zeolite layer of the Sankiz Formation of Campanian-Maastrichtian age within the flysch like sediments at Hekimhan in the northern part of the Malatya Basin. Characterization studies of the zeolite samples were done by XRF, XRD and SEM images and the results showed that the main structures of the zeolites were clinoptilolite-(Cs), heulandite and calcite and the geological occurrences of zeolite is in marine environments.

  10. Methods for delineating flood-prone areas in the Great Basin of Nevada and adjacent states

    USGS Publications Warehouse

    Burkham, D.E.

    1988-01-01

    The Great Basin is a region of about 210,000 square miles having no surface drainage to the ocean; it includes most of Nevada and parts of Utah, California, Oregon, Idaho, and Wyoming. The area is characterized by many parallel mountain ranges and valleys trending north-south. Stream channels usually are well defined and steep within the mountains, but on reaching the alluvial fan at the canyon mouth, they may diverge into numerous distributary channels, be discontinuous near the apex of the fan, or be deeply entrenched in the alluvial deposits. Larger rivers normally have well-defined channels to or across the valley floors, but all terminate at lakes or playas. Major floods occur in most parts of the Great Basin and result from snowmelt, frontal-storm rainfall, and localized convective rainfall. Snowmelt floods typically occur during April-June. Floods resulting from frontal rain and frontal rain on snow generally occur during November-March. Floods resulting from convective-type rainfall during localized thunderstorms occur most commonly during the summer months. Methods for delineating flood-prone areas are grouped into five general categories: Detailed, historical, analytical, physiographic, and reconnaissance. The detailed and historical methods are comprehensive methods; the analytical and physiographic are intermediate; and the reconnaissance method is only approximate. Other than the reconnaissance method, each method requires determination of a T-year discharge (the peak rate of flow during a flood with long-term average recurrence interval of T years) and T-year profile and the development of a flood-boundary map. The procedure is different, however, for each method. Appraisal of the applicability of each method included consideration of its technical soundness, limitations and uncertainties, ease of use, and costs in time and money. Of the five methods, the detailed method is probably the most accurate, though most expensive. It is applicable to

  11. First occurrence of the Salvador Formation in the Jatobá Basin (Pernambuco, Northeast Brazil): Facies characterization and depositional systems

    NASA Astrophysics Data System (ADS)

    Horn, Bruno Ludovico Dihl; Melo Ferrer de Morais, Débora

    2016-12-01

    Fan deltas, constituting proximal depositional systems adjacent to boundary faults, are common features associated with rift basins. The Cretaceous fan delta systems of the Salvador Formation, deposited during the rift phase of the Recôncavo-Tucano-Jatobá Basin, were first reported in the Recôncavo Basin and later discovered in the Tucano Basin. Because of the absence of any outcrops in the Jatobá Basin until now, these alluvial fans were interpreted solely through seismic analysis. We report the first revealed outcrops of the Salvador Formation in that basin and characterize their depositional systems as interlayered with the lacustrine Candeias Formation. Based on facies and architecture, the alluvial system can be subdivided into three associations: (1) proximal fan delta, characterized by meter-scale conglomerate bodies with a predominance of boulders and cobbles with thin sandstone layers; (2) distal fan delta, characterized by sheet-like pebble conglomerate and sandstone layers with flame and load structures; and (3) lacustrine, further subdivided into shallow lake facies reddish shales and mudstones with oolitic limestones and deep lake facies grey to green shales with pyrite. Paleocurrent measurements for the proximal fan association show paleoflow direction varying from SW to SE, which is expected for the rift phase alluvial system. The Recôncavo-Tucano-Jatobá rift system has two conglomeratic units, namely the Salvador and Marizal Formations, the former a syn-rift and the latter a post-rift unit. The absence of sedimentary clasts in the conglomerates, very low maturity, the presence of giant clasts, and a visible relationship between boundary faults in the outcrop, define the syn-rift Salvador Formation characteristics. Based on the facies and paleocurrent analyses, the Salvador Formation deposits in Jatobá Basin were interpreted as a deposition of a debris flow-dominated fan delta, indicating the lacustrine setting represented by the Candeias

  12. Depositional history of the Lower Triassic Dinwoody Formation in the Wind River basin area, Wyoming

    SciTech Connect

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

    1993-04-01

    Thirty-three measured sections of the Dinwoody Formation, including five from the literature, provide information on thickness, lithology, paleontology, and stratigraphic relations within the Wind River basin and immediately adjacent areas of Wyoming. Most of these sections are in Fremont County, and some lie within the Wind River Indian Reservation. The Dinwoody becomes progressively thinner eastward, from a maximum thickness of 54.6 m in the northwestern Wind River Mountains to zero near the Natrona County line. The formation is characterized by yellowish-weathering, gray siltstone and silty shale. Variable amounts of limestone, sandstone, gypsum, and claystone are also present. Marine bivalves, gastropods, brachiopods (Lingula), and conodonts are common in the western part of the study area, but are absent to the northeast in gypsiferous strata, and near the eastern limit of Dinwoody deposition. The Dinwoody in the Wind River Basin area was deposited unconformably on the Upper Permian Ervary Member of the Park City Formation during the initial Mesozoic flood onto the Wyoming shelf during the Griesbachian, and represents the first of three Lower Triassic transgressive sequences in the western miogeocline. Conodonts of the Isarcica Chronozone document the rapid nature of this eastward transgression. The Permian surface underlying the Dinwoody rarely shows evidence of the long hiatus separating rocks of this age and earliest Triassic deposits. The Dinwoody transgression was followed by westward progradation of the Red Peak Formation of the Chugwater Group across the study area.

  13. Hydrology and snowmelt simulation of Snyderville Basin, Park City, and adjacent areas, Summit County, Utah

    USGS Publications Warehouse

    Brooks, Lynette E.; Mason, James L.; Susong, David D.

    1998-01-01

    Increasing residential and commercial development is placing increased demands on the ground- and surface-water resources of Snyderville Basin, Park City, and adjacent areas in the southwestern corner of Summit County, Utah. Data collected during 1993-95 were used to assess the quantity and quality of the water resources in the study area.Ground water within the study area is present in consolidated rocks and unconsolidated valley fill. The complex geology makes it difficult to determine the degree of hydraulic connection between different blocks of consolidated rocks. Increased ground-water withdrawal during 1983- 95 generally has not affected ground-water levels. Ground-water withdrawal in some areas, however, caused seasonal fluctuations and a decline in ground-water levels from 1994 to 1995, despite greater-than-normal recharge in the spring of 1995.Ground water generally has a dissolved-solids concentration that ranges from 200 to 600 mg/L. Higher sulfate concentrations in water from wells and springs near Park City and in McLeod Creek and East Canyon Creek than in other parts of the study area are the result of mixing with water that discharges from the Spiro Tunnel. The presence of chloride in water from wells and springs near Park City and in streams and wells near Interstate Highway 80 is probably caused by the dissolution of applied road salt. Chlorofluorocarbon analyses indicate that even though water levels rise within a few weeks of snowmelt, the water took 15 to 40 years to move from areas of recharge to areas of discharge.Water budgets for the entire study area and for six subbasins were developed to better understand the hydrologic system. Ground-water recharge from precipitation made up about 80 percent of the ground-water recharge in the study area. Ground-water discharge to streams made up about 40 percent of the surface water in the study area and ground-water discharge to springs and mine tunnels made up about 25 percent. Increasing use of

  14. Mass-movement deposits in the lacustrine Eocene Green River Formation, Piceance Basin, western Colorado

    USGS Publications Warehouse

    Johnson, Ronald C.; Birdwell, Justin E.; Brownfield, Michael E.; Mercier, Tracey J.

    2015-01-01

    The Eocene Green River Formation was deposited in two large Eocene saline lakes, Lake Uinta in the Uinta and Piceance Basins and Lake Gosiute in the Greater Green River Basin. Here we will discuss mass-movement deposits in just the Piceance Basin part of Lake Uinta.

  15. Megabreccia deposits in an extensional basin: The Miocene-Pliocene Horse Camp Formation, east-central Nevada

    SciTech Connect

    Schmitt, J.G.; Brown, C.L. )

    1991-06-01

    Three varieties of megabreccia deposits are present in alluvial-lacustrine extensional basin fill of the Miocene-Pliocene Horse Camp Formation of east-central Nevada. Coherent debris sheets (150-300 m thick; up to 1,500 m long) consist of Oligocene-Miocene volcanic rock masses which are internally fractured yet retain their stratigraphic integrity. Fracture zones show variable amounts of displacement (up to 5 cm) and brecciation. These debris sheets overlie horizontally stratified sandstone and laminated claystone interpreted as playa deposits and are overlain by lithified grus. Emplacement of these coherent debris sheets was by landslide or block slide. Associated deposits of large boulders within playa facies suggest gliding of blocks broken from the edges of the landslides across wet playa surfaces. Large (1.6 - 2.4 km-long) allochthonous blocks consist of intact Paleozoic and Tertiary volcanic stratigraphic sequences which are brecciated and attenuated. Brecciation is accompanied in places by incorporation of muddy sand matrix. These blocks may be fragments of the upper plate of low-angle detachment faults which broke away as gravity-driven blocks from the nearby Horse Range and slid along the uplifted former detachment surface into the adjacent Horse Camp basin. Megabreccia deposits characterize Teritary extensional basins in western North America. Detailed analysis of their stratigraphic, sedimentologic, and structural relations can provide a better understanding of the complex tectonosedimentary history of these basins.

  16. Timing the structural events in the Palaeoproterozoic Bolé-Nangodi belt terrane and adjacent Maluwe basin, West African craton, in central-west Ghana

    NASA Astrophysics Data System (ADS)

    de Kock, G. S.; Théveniaut, H.; Botha, P. M. W.; Gyapong, W.

    2012-04-01

    The Maluwe basin, north-adjacent to the Sunyani basin, is the northernmost of the northeast-trending Eburnean volcaniclastic depositories in Ghana. These basins are separated from one another by remnants of Eoeburnean crust, all formed during the evolution of an arc-backarc basins complex in a Palaeoproterozoic intraoceanic environment. The Bolé-Nangodi belt terrane to the northwest, of mostly Eoeburnean crust is fault bounded with the Maluwe basin along the northeast-trending Bolé-Navrongo fault zone. The stratigraphic sequence, which was the key to unravelling the structural evolution of the study area, was established by means of field observations aided by precision SHRIMP geochronology. The quartzitic, pelitic, quartzofeldspathic and granitic gneisses of the Eoeburnean crust (>2150 Ma) experienced complex metamorphic mineral growth and migmatitization, mostly under static crustal conditions and were subjected to several deformation episodes. The foliated mafic and metasedimentary enclaves within the Ifanteyire granite establish deformation to have taken place prior to ˜2195 Ma, while the tectonically emplaced Kuri amphibolites within the 2187-Ma gneissic Gondo granite indicate a stage of rifting followed by collision. Deformation of granite dykes in the Gondo granites at ˜2150 Ma concluded the development of the Eoeburnean orogenic cycle (DEE). The Sawla Suite, contemporaneous with the deposition of the Maluwe Group, intruded the tectonic exhumed Bolé-Nangodi terrane during extension between ˜2137 and 2125 Ma. The rifting separated the Abulembire fragment from the Bolé-Nangodi terrane. During subsequent northwestward subduction of young back-arc basin oceanic crust the volcaniclastic strata of the Maluwe Group and Sawla granitoids were deformed (DE1) under chlorite/sericite greenschist-grade conditions. The NE-trending folds had subhorizontal axes and subvertical axial planes. Simultaneous to the DE1 orogenesis the molasses of the Banda Group was

  17. Geochemistry of ground water in alluvial basins of Arizona and adjacent parts of Nevada, New Mexico, and California

    USGS Publications Warehouse

    Robertson, Frederick N.

    1991-01-01

    Chemical and isotope analyses of ground water from 28 basins in the Basin and Range physiographic province of Arizona and parts of adjacent States were used to evaluate ground-water quality, determine processes that control ground-water chemistry, provide independent insight into the hydrologic flow system, and develop information transfer. The area is characterized by north- to northwest-trending mountains separated by alluvial basins that form a regional topography of alternating mountains and valleys. On the basis of ground-water divides or zones of minimal basin interconnection, the area was divided into 72 basins, each representing an individual aquifer system. These systems are joined in a dendritic pattern and collectively constitute the major water resource in the region. Geochemical models were developed to identify reactions and mass transfer responsible for the chemical evolution of the ground water. On the basis of mineralogy and chemistry of the two major rock associations of the area, a felsic model and a mafic model were developed to illustrate geologic, climatic, and physiographic effects on ground-water chemistry. Two distinct hydrochemical processes were identified: (1) reactions of meteoric water with minerals and gases in recharge areas and (2) reactions of ground water as it moves down the hydraulic gradient. Reactions occurring in recharge and downgradient areas can be described by a 13-component system. Major reactions are the dissolution and precipitation of calcite and dolomite, the weathering of feldspars and ferromagnesian minerals, the formation of montmorillonite, iron oxyhydroxides, and probably silica, and, in some basins, ion exchange. The geochemical modeling demonstrated that relatively few phases are required to derive the ground-water chemistry; 14 phases-12 mineral and 2 gas-consistently account for the chemical evolution in each basin. The final phases were selected through analysis of X-ray diffraction and fluorescence data

  18. Peleolakes and impact basins in southern Arabia Terra, including Meridiani Planum: Implications for the formation of hematite deposits on Mars

    USGS Publications Warehouse

    Newsom, Horton E.; Barber, C.A.; Hare, T.M.; Schelble, R.T.; Sutherland, V.A.; Feldman, W.C.

    2003-01-01

    The hematite deposit in Meridiani Planum was selected for a Mars Exploration Rover (MER) landing site because water could be involved in the formation of hematite, and water is a key ingredient in the search for life. Our discovery of a chain of paleolake basins and channels along the southern margin of the hematite deposits in Meridiani Planum with the presence of the strongest hematite signature adjacent to a paleolake basin, supports the possible role of water in the formation of the hematite and the deposition of other layered materials in the region. The hematite may have formed by direct precipitation from lake water, as coatings precipitated from groundwater, or by oxidation of preexisting iron oxide minerals. The paleolake basins were fed by an extensive channel system, originating from an area larger than Texas and located south of the Schiaparelli impact basin. On the basis of stratigraphic relationships, the formation of channels in the region occurred over much of Mars' history, from before the layered materials in Meridiani Planum were deposited until recently. The location of the paleolake basins and channels is connected with the impact cratering history of the region. The earliest structure identified in this study is an ancient circular multiringed basin (800-1600 km diameter) that underlies the entire Meridiani Planum region. The MER landing site is located on the buried northern rim of a later 150 km diameter crater. This crater is partially filled with layered deposits that contained a paleolake in its southern portion. Copyright 2003 by the American Geophysical Union.

  19. The concentration of radionuclides and metals in vegetation adjacent to and in the SRL Seepage Basins

    SciTech Connect

    Murphy, C. E. Jr.

    1992-12-14

    In 1991 the trees on the dikes surrounding the SRL Seepage Basins were sampled and analyzed to inventory the contaminants transported from the basins into the vegetation. Tree leaves and wood were collected and analyzed for {sup 90}Sr, {sup 60}Co, {sup 137}Cs, {sup 238}Pu, {sup 239,240}Pu, {sup 242,244}Cm, {sup 241}Am, Ba, Cr, Hg, Mg, Mn, Ni, and Pb. The concentrations of contaminants were influenced by sample type (leaves versus wood), species type (pines versus hardwoods), and location relative to distance from the basin. The total inventory of each contaminant in the trees was estimated. The relationships between leaf and wood, pines and hardwood, location, and mass of the material in each of these classes were used to weight the total inventory estimate. The radionuclide with the largest inventory was 0.7 mCi for {sup 90}Sr. The metallic contaminant with the largest inventory was Mn at 200 gm.

  20. The concentration of radionuclides and metals in vegetation adjacent to and in the SRL Seepage Basins

    SciTech Connect

    Murphy, C. E. Jr.

    1992-12-14

    In 1991 the trees on the dikes surrounding the SRL Seepage Basins were sampled and analyzed to inventory the contaminants transported from the basins into the vegetation. Tree leaves and wood were collected and analyzed for [sup 90]Sr, [sup 60]Co, [sup 137]Cs, [sup 238]Pu, [sup 239,240]Pu, [sup 242,244]Cm, [sup 241]Am, Ba, Cr, Hg, Mg, Mn, Ni, and Pb. The concentrations of contaminants were influenced by sample type (leaves versus wood), species type (pines versus hardwoods), and location relative to distance from the basin. The total inventory of each contaminant in the trees was estimated. The relationships between leaf and wood, pines and hardwood, location, and mass of the material in each of these classes were used to weight the total inventory estimate. The radionuclide with the largest inventory was 0.7 mCi for [sup 90]Sr. The metallic contaminant with the largest inventory was Mn at 200 gm.

  1. Depositional model for carbonate-evaporite cyclicity: Middle Pennsylvanian of Paradox basin

    SciTech Connect

    Kendall, A.C.

    1987-05-01

    The Paradox basin is a classic area for the study of relations between carbonates and evaporites. Previous depositional models assume carbonates and evaporites are coeval, implying that the evaporites were deep water deposits. Stratigraphic relationships are, however, complicated by previously unrecognized salt dissolution. Restoration of the missing salts indicates that evaporites entirely postdate marine carbonates in each cycle. Anhydrites and silty dolomites that succeed halites are reinterpreted as shallow hypersaline to subaerial deposits. These playa-like sediments are abruptly overlain by organic-rich shales that represent anoxic and the deepest-water deposits in the sequence. Paradox basin salts and succeeding playa deposits formed in a deep but desiccated basin. Sea level rises drowned the formerly exposed basin rims, causing sudden complete floodings of the basin and the abrupt contacts between playa deposits and deep-water shales. The shale-carbonate-evaporite sequences that form lower parts of cycles resulted from sea level falls. These ultimately exposed basin rims, isolating the basin, and allowed evaporative draw down and the deposition of basin-central evaporites. In contrast, the halite-anhydrite-silty dolomite sequences of the upper parts of cycles arose when sediment aggradation caused expansion of the evaporite depositional area onto basin flanks. There brine reflux became more significant. This reduced residence times of brines in the basin so that, progressively, salinities decreased and only less-saline sediments were able to persist in the playa environment. Cycles end (or begin) when renewed sea level rises drowned the basin-central playas.

  2. Deformation Rates in the Snake River Plain and Adjacent Basin and Range Regions Based on GPS Measurements

    NASA Astrophysics Data System (ADS)

    Payne, S. J.; McCaffrey, R.; King, R. W.; Kattenhorn, S. A.

    2012-12-01

    We estimate horizontal velocities for 405 sites using Global Positioning System (GPS) phase data collected from 1994 to 2010 within the Northern Basin and Range Province, U.S.A. The velocities reveal a slowly-deforming region within the Snake River Plain in Idaho and Owyhee-Oregon Plateau in Oregon separated from the actively extending adjacent Basin and Range regions by shear. Our results show a NE-oriented extensional strain rate of 5.6 ± 0.7 nanostrain/yr in the Centennial Tectonic Belt and an ~E-oriented extensional strain rate of 3.5 ± 0.2 nanostrain/yr in the Great Basin. These extensional rates contrast with the very low strain rate within the 125 km x 650 km region of the Snake River Plain and Owyhee-Oregon Plateau which is not distinguishable from zero (-0.1 ± 0.4 x nanostrain/yr). Inversions of Snake River Plain velocities with dike-opening models indicate that rapid extension by dike intrusion in volcanic rift zones, as previously hypothesized, is not currently occurring. GPS data also disclose that rapid extension in the surrounding regions adjacent to the slowly-deforming region of the Snake River Plain drives shear between them. We estimate right-lateral shear with slip rates of 0.3-1.5 mm/yr along the northwestern boundary adjacent to the Centennial Tectonic Belt and left-lateral oblique extension with slip rates of 0.5-1.5 mm/yr along the southeastern boundary adjacent to the Intermountain Seismic Belt. The fastest lateral shearing evident in the GPS occurs near the Yellowstone Plateau where earthquakes with right-lateral strike-slip focal mechanisms are within a NE-trending zone of seismicity. The regional velocity gradients are best fit by nearby poles of rotation for the Centennial Tectonic Belt, Snake River Plain, Owyhee-Oregon Plateau, and eastern Oregon, indicating that clockwise rotation is not locally driven by Yellowstone hotspot volcanism, but instead by extension to the south across the Wasatch fault possibly due to gravitational

  3. Processes in Environmental Depositional Systems and Deformation in Sedimentary Basins: Goals for Exoloration in Mexico

    NASA Astrophysics Data System (ADS)

    Sandoval-Ochoa, J.

    2005-05-01

    Among the recent needs to establish new goals in the mexican energy industry to increase the petroleum reserves, has been necessary to recapitulate on some academic an operative concepts and definitions applied to the Petroliferous Basins Exploration; first of all, in order to understand the Petroleum System in given tectonophysical framework. The tectonophysical environment experienced by the petroliferous basin in the southwestern Gulf of Mexico, merely in the Campeche Sound and adjacent terrestrial regions (Figure 1); has been the result of interaction among the tectonic plates, the Coco's Plate with impingement and subduction beneath the Northamerican Plate and the Yucatán Microplate and even in very deep connection with the oceanic crust of southwesternmost portion of the Gulf of Mexico and the one of the Caribbean sea beneath the gulf of Belize-Honduras. The tectonosedimentary effects in the Campeche Bay starting with the skeleton formed for the Cenozoic Era, kept simultaneous conditions in depositions and deformations because of strain, stress and collapse fields, acted through this Era up to the present day, as observed in the surface Aguayo et al, 1999 and Sandoval, 2000. The involved portions of the crust and its boundaries have also been performing the relative sinking of the mere southwestern centre of the Gulf of Mexico, and the rising of the southeastern lands of Mexico. In the middle contiguity are found the productive Tertiary basins of: Comalcalco, Macuspana, Salina del Itsmo, Campeche-Champoton and other in deep waters; all of them, in an arrangement of basins among distensive faulted blocks in echelon, falling down to the deep centre of the Gulf Sandoval, op cit. With this scenario and that ones of other basins, a recapitulation on concepts and definitions, has been made on the regional natural processes of the environmental depositional systems and on the basins analysis in the tectonophysical framework, in order to reflect on the

  4. Water resources in basin-fill deposits in the Tularosa Basin, New Mexico

    USGS Publications Warehouse

    Orr, B.R.; Myers, R.G.

    1986-01-01

    The Tularosa Basin, a faulted intermontane depression in south-central New Mexico, contains a thick sequence of alluvial and lacustrine deposits of Tertiary and Quaternary age. Most of these sediments are saturated with very saline water. Freshwater supplies (dissolved solids concentration < 1000 mg/L) principally are found in alluvial fans located around the basin margin. On the eastern side of the Tularosa Basin, fresh groundwater supplies are limited to alluvial fan deposits from Grapevine Canyon to about 3 mi south of Alamogordo. Data from surface geophysical surveys indicate that about 1.4 to 2.1 million acre-ft of freshwater may be in storage in this area, not all of which is recoverable. An additional 3.6 to 5.4 million acre-ft of slightly saline water (dissolved solids concentration 1000 to 3000 mg/L) may be in storage in the same area, again not all of which is recoverable. On the western side of the Tularosa Basin, alluvial fans in the vicinity of Rhodes Canyon may contain freshwater. Geophysical data indicate the freshwater zone may be as thick as 1500 ft in places; however, the limited number of wells in this area precludes a precise definition of the volume of freshwater in storage. To the south, freshwater is present in alluvial fans associated with the Ash Canyon drainage system. Geophysical data indicate that perhaps as much as 450,000 acre-ft of freshwater, not all recoverable, may be in storage in this area. Fan deposits between Ash Canyon and Rhodes canyon may contain additional freshwater supplies. Possibly 10.7 million acre-ft of freshwater, not all of which is recoverable, may be in storage on the western side of the Tularosa Basin. Possibly 180 million acre-ft of brine (concentrations of dissolved solids exceeding 35,000 mg/L), not all of which is recoverable, may be in storage in the Tularosa Basin. Information is sparse concerning the capability of saline aquifers in the Tularosa Basin to store and transmit fluid. (Author 's abstract)

  5. An ecological study of the KSC Turning Basin and adjacent waters

    NASA Technical Reports Server (NTRS)

    Nevin, T. A.; Lasater, J. A.; Clark, K. B.; Kalajian, E. H.

    1974-01-01

    The conditions existing in the waters and bottoms of the Turning Basin, the borrow pit near Pad 39A, and the Barge Canal connecting them were investigated to determine the ecological significance of the chemical, biological, and microbiological parameters. The water quality, biological, microbiological findings are discussed. It is recommended that future dredging activities be limited in depth, and that fill materials should not be removed down to the clay strata.

  6. 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.

  7. 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

  8. Reevaluation of the Bedford--Berea sequence on Ohio and adjacent states: New perspectives on sedimentation and tectonics in foreland basins

    SciTech Connect

    Pashin, J.C. ); Ettensohn, F.R. )

    1992-01-01

    The Late Devonian Bedford-Berea (BB) sequence provided an early basis for models of epeiric sedimentation, but controversy regarding its origin has arisen in recent years. This study was designed to resolve this controversy and to identify factors that control depositional architecture in foreland basins on the basis of outcrop and subsurface data. The BB is a siliciclastic succession that was deposited in the Appalachian foreland basin during a relaxational phase of the Acadian orogeny. Among the salient features of the BB are an eastern platform and a western basin. The platform was characterized largely by erosion of Catskill sediment and subsequent deposition of aggradational valley-fill sequences, whereas the basin was characterized mainly by progradational delta and shelf deposits that overlie conformably the distalmost part of the Catskill clastic wedge. BB depositional history and paleogeography is divided into two episodes: (1) basin filling and (2) delta destruction. Basin filling was characterized by regressive fluvial-deltaic systems that eroded the Catskill wedge and supplied prograding deltaic and shelf sediment to the western basin. Delta destruction began after the basin was full with sediment and was dominated by flexural relaxation, which gave rise to unusual facies patterns. Delta-front deposits in the western basin were uplifted and reworked, and a shelf silt blanket prograded back toward the incised valleys on the rapidly subsiding eastern platform where estuaries were forming. Reevaluation of the BB sequence demonstrates that the depositional architecture and paleogeographic history of foreland basins is much more elaborate than is commonly recognized. Tectonism, relict topography, differential compaction, and relative sea-level variation functioned collectively to determine the complex depositional history and paleogeography of the BB sequence.

  9. Late Quaternary stratigraphy and depositional history of the Long Island Sound basin

    USGS Publications Warehouse

    Lewis, Ralph S.; Stone, Janet R.

    1991-01-01

    Where quiet waters prevail, marine mud generally less than 15 m thick blankets the older deposits of the Basin. Elsewhere, especially in eastern LIS, tidal currents are actively reworking and transporting glacial and postglacial deposits.

  10. Heat flow in the Lesser Antilles island arc and adjacent back arc Grenada basin

    NASA Astrophysics Data System (ADS)

    Manga, Michael; Hornbach, Matthew J.; Le Friant, Anne; Ishizuka, Osamu; Stroncik, Nicole; Adachi, Tatsuya; Aljahdali, Mohammed; Boudon, Georges; Breitkreuz, Christoph; Fraass, Andrew; Fujinawa, Akihiko; Hatfield, Robert; Jutzeler, Martin; Kataoka, Kyoko; Lafuerza, Sara; Maeno, Fukashi; Martinez-Colon, Michael; McCanta, Molly; Morgan, Sally; Palmer, Martin R.; Saito, Takeshi; Slagle, Angela; Stinton, Adam J.; Subramanyam, K. S. V.; Tamura, Yoshihiko; Talling, Peter J.; Villemant, Benoit; Wall-Palmer, Deborah; Wang, Fei

    2012-08-01

    Using temperature gradients measured in 10 holes at 6 sites, we generate the first high fidelity heat flow measurements from Integrated Ocean Drilling Program drill holes across the northern and central Lesser Antilles arc and back arc Grenada basin. The implied heat flow, after correcting for bathymetry and sedimentation effects, ranges from about 0.1 W/m2 on the crest of the arc, midway between the volcanic islands of Montserrat and Guadeloupe, to <0.07 W/m2 at distances >15 km from the crest in the back arc direction. Combined with previous measurements, we find that the magnitude and spatial pattern of heat flow are similar to those at continental arcs. The heat flow in the Grenada basin to the west of the active arc is 0.06 W/m2, a factor of 2 lower than that found in the previous and most recent study. There is no thermal evidence for significant shallow fluid advection at any of these sites. Present-day volcanism is confined to the region with the highest heat flow.

  11. Heat flow in the Lesser Antilles island arc and adjacent back arc Grenada basin

    NASA Astrophysics Data System (ADS)

    Manga, M.; Hornbach, M. J.; Le Friant, A.; Ishizuka, O.; Stroncik, N.

    2012-12-01

    Using temperature gradients measured in 10 holes at 6 sites, we generate the first high fidelity heat flow measurements from Integrated Ocean Drilling Program drill holes across the northern and central Lesser Antilles arc and back arc Grenada basin. The implied heat flow, after correcting for bathymetry and sedimentation effects, ranges from about 0.1 W/m2 on the crest of the arc, midway between the volcanic islands of Montserrat and Guadeloupe, to < 0.07 W/m2 at distances > 15 km from the crest in the back arc direction. Combined with previous measurements, we find that the magnitude and spatial pattern of heat flow are similar to those at continental arcs. The heat flow in the Grenada basin to the west of the active arc is 0.06 W/m2, a factor of 2 lower than that found in the previous and most recent study. There is no thermal evidence for significant shallow fluid advection at any of these sites. Present day volcanism is confined to the region with the highest heat flow.

  12. Heat flow in the Lesser Antilles island arc and adjacent back arc Grenada basin

    NASA Astrophysics Data System (ADS)

    Manga, Michael; Hornbach, Matt; Le Friant, Anne; Ishizuka, Osamu

    2014-05-01

    Using temperature gradients measured in 10 holes at 6 sites, we generate the first high fidelity heat flow measurements from Integrated Ocean Drilling Program drill holes across the northern and central Lesser Antilles arc and back arc Grenada basin. The implied heat flow, after correcting for bathymetry and sedimentation effects, ranges from about 0.1 W/m2 on the crest of the arc, midway between the volcanic islands of Montserrat and Guadeloupe, to < 0.07 W/m2 at distances > 15 km from the crest in the back arc direction. Combined with previous measurements, we find that the magnitude and spatial pattern of heat flow are similar to those at continental arcs. The heat flow in the Grenada basin to the west of the active arc is 0.06 W/m2, a factor of 2 lower than that found in the previous and most recent study. There is no thermal evidence for significant shallow fluid advection at any of these sites. Present day volcanism is confined to the region with the highest heat flow.

  13. A modern analog for carbonate source-to-sink sedimentary systems: the Glorieuses archipelago and adjacent basin (SW Indian Ocean)

    NASA Astrophysics Data System (ADS)

    Jorry, S.; Jouet, G.; Prat, S.; Courgeon, S.; Le Roy, P.; Camoin, G.; Caline, B.

    2014-12-01

    This study presents the geomorphological and sedimentological analysis of a modern carbonate source-to-sink system located north of Madagascar (SW Indian Ocean). The sedimentary system is composed of an isolated carbonate platform sited on top of a seamount rising steeply from the seabed located at 3000 m water depth. The slope of the seamount is incised by canyons, and meandering channels occur above lobbed sedimentary bodies at the foot of the slope. The dataset consists of dredges, sediment piston cores, swath bathymetry and seismic (sparker and 2D high-resolution) lines collected from inner platform (less than 5 m deep) to the adjacent deep sedimentary basin. Particle size analysis and composition of carbonate grains are used to characterize the distribution and heterogeneity of sands accumulated on the archipelago. Main results show that composition of carbonate sediments is dominated by segments of Halimeda, large benthic foraminifera, coral debris, molluscs, echinoderms, bryozoans and sponges. According to the shape and the position of sandwaves and intertidal sandbars developed in the back-barrier reef, the present organization of these well-sorted fine-sand accumulations appears to be strongly influenced by flood tidal currents. Seismic lines acquired from semi-enclosed to open lagoon demonstrate that most of the sediment is exported and accumulated along the leeward margin of the platform, which is connected to a canyon network incising the outer slope. Following the concept of highstand shedding of carbonate platforms (Schlager et al., 1994), excess sediment is exported by plumes and gravity flows to the adjacent deep sea where it feeds a carbonate deep-sea fan. Combined observations from platform to basin allow to explain how the Glorieuses carbonate source to sink system has evolved under the influence of climate and of relative sea-level changes since the last interglacial.

  14. Deposition of Asian Dust in the Tahoe Basin and the Impact of Climate Patterns on Deposition

    NASA Astrophysics Data System (ADS)

    Snyder, Jason

    Routine monitoring of fine aerosols in the Lake Tahoe basin began with the Tahoe Regional Planning Association (TRPA) in 1988 (Molenar et. al., 1994). During this time two sites of aerosol impact analysis were chosen based on prior work done by the ARB (Cahill et. al., 1997). These sites included Bliss SP, which is located near Emerald Bay at 200 m Lake Tahoe. Aerosols deposited at the Bliss SP site during each spring from 1988 to 2004, were predominately from sources outside of the Lake Tahoe basin and contained signatures from an "unknown north Sacramento Valley source" (Cahill and Cliff, 2002). The aerosols amounted to about ½ of all fine soil seen at South Lake Tahoe. With a better knowledge regarding the efficiency of the transport of fine aerosol plumes across the Pacific Ocean to North American combined with the presence of Asian dust signatures at other sites including Crater Lake and the Yukon, it was now determined that the source of fine particles to the Lake Tahoe basin was possibly Asian in origin. For this study, aerosols were collected during spring 2006, which coincides with the annual peak of Asian dust transport toward North America. Aerosols were collected at the TERC Tahoe Fish Hatchery, a relatively pollution free site northeast of Tahoe City. Aerosol collections at this site were done on an offshore pier, which reduced the amount of contamination for shore sources of aerosols and pollution such as road dust. The result was the identification of Asian dust signatures in aerosol deposition data for the period of April 28 to May 15, 2006. Such dust plumes were identified using HYSPLIT trajectories. Chemical signatures were also used including the Fe/Ca ratio, which is unique in Asian dust plumes. The particulate matter in these dust plumes produce a regional haze across the Lake Tahoe basin, which could impact incoming solar radiation. Furthermore, deposition of particles from the aerosol plume into the lake not only contributed to suspended

  15. Geohydrology of the Aucilla-Suwannee-Ochlockonee River Basin, south-central Georgia and adjacent parts of Florida

    USGS Publications Warehouse

    Torak, Lynn J.; Painter, Jaime A.; Peck, Michael F.

    2010-01-01

    Major streams and tributaries located in the Aucilla-Suwannee-Ochlockonee (ASO) River Basin of south-central Georgia and adjacent parts of Florida drain about 8,000 square miles of a layered sequence of clastic and carbonate sediments and carbonate Coastal Plain sediments consisting of the surficial aquifer system, upper semiconfining unit, Upper Floridan aquifer, and lower confining unit. Streams either flow directly on late-middle Eocene to Oligocene karst limestone or carve a dendritic drainage pattern into overlying Miocene to Holocene sand, silt, and clay, facilitating water exchange and hydraulic connection with geohydrologic units. Geologic structures operating in the ASO River Basin through time control sedimentation and influence geohydrology and water exchange between geohydrologic units and surface water. More than 300 feet (ft) of clastic sediments overlie the Upper Floridan aquifer in the Gulf Trough-Apalachicola Embayment, a broad area extending from the southwest to the northeast through the center of the basin. These clastic sediments limit hydraulic connection and water exchange between the Upper Floridan aquifer, the surficial aquifer system, and surface water. Accumulation of more than 350 ft of low-permeability sediments in the Southeast Georgia Embayment and Suwannee Strait hydraulically isolates the Upper Floridan aquifer from land-surface hydrologic processes in the Okefenokee Basin physiographic district. Burial of limestone beneath thick clastic overburden in these areas virtually eliminates karst processes, resulting in low aquifer hydraulic conductivity and storage coefficient despite an aquifer thickness of more than 900 ft. Conversely, uplift and faulting associated with regional tectonics and the northern extension of the Peninsular Arch caused thinning and erosion of clastic sediments overlying the Upper Floridan aquifer southeast of the Gulf Trough-Apalachicola Embayment near the Florida-Georgia State line. Limestone dissolution in

  16. Properties of basin-fill deposits, a 1971–2000 water budget, and surface-water-groundwater interactions in the upper Humboldt River basin, northeastern Nevada

    USGS Publications Warehouse

    Plume, Russell W.; Smith, Jody L.

    2013-01-01

    This study was done in cooperation with Elko County, Nevada in response to concerns over growing demand for water within the county and increasing external demands that are occurring statewide. The upper Humboldt River basin encompasses 4,360 square miles in northeastern Nevada and includes the headwaters area of the Humboldt River. Nearly all of the mean annual flow of the Humboldt River originates in this area. Basin-fill deposits function as the principal aquifers in the upper Humboldt River basin. Over much of the basin lowlands, the upper 200 feet of basin fill consists of clay, silt, sand, and gravel deposited in a lake of middle to late Pliocene age. Fine-grained lacustrine sediments compose from 30 to more than 70 percent of the deposits. Mean values of transmissivity are less than 1,000 feet squared per day. Total inflow to the upper Humboldt River basin, about 3,330,000 acre-feet per year, is entirely from annual precipitation. Total outflow from the basin, about 3,330,000 acre-feet per year, occurs as evapotranspiration, streamflow, subsurface flow, and pumpage. The uncertainty of these values of inflow and outflow is estimated to be 25 percent. Baseflow of the Humboldt River is minimal upstream of the Elko Hills and in downstream reaches almost all baseflow comes from tributary inflow of the North Fork and South Fork Humboldt Rivers. However, the baseflow of these two tributaries comes from groundwater discharge to their respective channels in canyons incised in volcanic rocks along the North Fork and in carbonate rocks along the South Fork. Water levels in the shallow water-table aquifer along the Humboldt River flood plain fluctuate with changes in stage of the river. During high rising river stage in spring and early summer, streamflow enters the aquifer as bank storage. As stage begins to decline in early to mid-summer groundwater in bank storage begins discharging back into the river channel and this continues through late summer. In years of below

  17. Uranium deposits at Shinarump Mesa and some adjacent areas in the Temple Mountain district, Emery County, Utah

    USGS Publications Warehouse

    Wyant, Donald G.

    1953-01-01

    Deposits of uraniferous hydrocarbons are associated with carnotite in the Shinarump conglomerate of Triassic age at Shinarump Mesa and adjacent areas of the Temple Mountain district in the San Rafael Swell of Emery County, Utah. The irregular ore bodies of carnotite-bearing sandstone are genetically related to lenticular uraniferous ore bodies containing disseminated asphaltitic and humic hydrocarbon in permeable sandstones and were localized indirectly by sedimentary controls. Nearly non-uraniferous bitumen commonly permeates the sandstones in the Shinarump conglomerate and the underlying Moekopi formation in the area. The ore deposits at Temple Mountain have been altered locally by hydrothermal solutions, and in other deposits throughout the area carnotite has been transported by ground and surface water. Uraniferous asphaltite is thought to be the non-volatile residue of an original weakly uraniferous crude oil that migrated into the San Rafael anticline; the ore metals concentrated in the asphaltite as the oil was devolatilized and polymerized. Carnotite is thought to have formed from the asphaltite by ground water leaching. It is concluded that additional study of the genesis of the asphaltitic uranium ores in the San Rafael Swell, of the processes by which the hydrocarbons interact and are modified (such as heat, polymerization, and hydrogenation under the influence of alpha-ray bombardment), of petroleum source beds, and of volcanic intrusive rocks of Tertiary age are of fundamental importance in the continuing study of the uranium deposits on the Colorado Plateau.

  18. Climatic and hydrologic oscillations in the Owens Lake basin and adjacent Sierra Nevada, California

    SciTech Connect

    Benson, L.V.; Burdett, J.W.; Phillips, F.M.

    1996-11-01

    Oxygen isotope and total organic carbon values of cored sediments from the Owens Lake basin, California, indicate that Owens Lake overflowed most of the time between 52,500 and 12,500 carbon-14 ({sup 14}C) years before present (B.P.). Owens Lake desiccated during or after Heinrich event H1 and was hydrologically closed during Heinrich event H2. The magnetic susceptibility and organic carbon content of cored sediments indicate that about 19 Sierra Nevada glaciations occurred between 52,500 and 23,500 {sup 14}C years B.P. Most of glacial advances were accompanied by decreases in the amount of discharge reaching Owens Lake. Comparison of the timing of glaciation with the lithic record of North Atlantic core V23-81 indicates that the number of mountain glacial cycles and the number of North Atlantic lithic events were about equal between 39,000 and 23,500 {sup 14}C years B.P. 27 refs., 3 figs.

  19. Subsurface geology of upper Tertiary and Quaternary deposits, coastal Louisiana and adjacent Continental Shelf

    SciTech Connect

    McFarlan, E. Jr.; Leroy, D.O.

    1988-09-01

    Upper Tertiary and Quaternary deposits thicken seaward from a feather edge on the outcrop in the uplands of southern Louisiana to more than 7000 ft (2134 m) beneath the middle continental shelf. Through a study of cores and cuttings from 100 control wells and electric-log pattern correlations from 350 water and petroleum industry wells with seismic corroboration in the offshore area, these deposits have been divided into six major time-stratigraphic units, four of which correlate to outcropping terraces. This investigation presents a regional stratigraphic framework of the major upper Tertiary and Quaternary units from their updip pinch-outs in and beneath the terraced uplands, into the subsurface, across the coastal plain to the Louisiana offshore area.

  20. Enhanced Seismic Imaging of Turbidite Deposits in Chicontepec Basin, Mexico

    NASA Astrophysics Data System (ADS)

    Chavez-Perez, S.; Vargas-Meleza, L.

    2007-05-01

    We test, as postprocessing tools, a combination of migration deconvolution and geometric attributes to attack the complex problems of reflector resolution and detection in migrated seismic volumes. Migration deconvolution has been empirically shown to be an effective approach for enhancing the illumination of migrated images, which are blurred versions of the subsurface reflectivity distribution, by decreasing imaging artifacts, improving spatial resolution, and alleviating acquisition footprint problems. We utilize migration deconvolution as a means to improve the quality and resolution of 3D prestack time migrated results from Chicontepec basin, Mexico, a very relevant portion of the producing onshore sector of Pemex, the Mexican petroleum company. Seismic data covers the Agua Fria, Coapechaca, and Tajin fields. It exhibits acquisition footprint problems, migration artifacts and a severe lack of resolution in the target area, where turbidite deposits need to be characterized between major erosional surfaces. Vertical resolution is about 35 m and the main hydrocarbon plays are turbidite beds no more than 60 m thick. We also employ geometric attributes (e.g., coherent energy and curvature), computed after migration deconvolution, to detect and map out depositional features, and help design development wells in the area. Results of this workflow show imaging enhancement and allow us to identify meandering channels and individual sand bodies, previously undistinguishable in the original seismic migrated images.

  1. The Shublik Formation and adjacent strata in northeastern Alaska description, minor elements, depositional environments and diagenesis

    USGS Publications Warehouse

    Tourtelot, Harry Allison; Tailleur, Irvin L.

    1971-01-01

    occurrence of silver and 300 ppm lead in gouge along a shear plane may be the result of metals introduced from an extraneous source. The deposits reflect a marine environment that deepened somewhat following deposition of the Sadlerochit Formation and then shoaled during deposition of the upper limestone-siltstone unit. This apparently resulted from a moderate transgression and regression of the sea with respect to a northwest-trending line between Barrow and the Brooks Range at the International Boundary. Nearer shore facies appear eastward. The phosphate in nodules, fossil molds and oolites, appears to have formed diagenetically within the uncompacted sediment.

  2. Intrashelf basins: A geologic model for source-bed and reservoir facies deposition within carbonate shelves

    SciTech Connect

    Grover, G. Jr. )

    1993-09-01

    Intrashelf basins (moats, inshore basins, shelf basins, differentiated shelf, and deep-water lagoons of others) are depressions of varying sizes and shapes that occur within tectonically passive and regionally extensive carbonate shelves. Intrashelf basins grade laterally and downdip (seaward) into shallow-water carbonates of the regional shelf, are separated from the open marine basin by the shelf margin, and are largely filled by fine-grained subtidal sediments having attributes of shallow- and deeper water sedimentation. These basins are commonly fringed or overlain by carbonate sands, reefs, or buildups. These facies may mimic those that occur along the regional shelf margin, and they can have trends that are at a high angle to that of the regional shelf. Intrashelf basins are not intracratonic basins. The history of most intrashelf basins is a few million to a few tens of million of years. Examples of intrashelf basins are known throughout the Phanerozoic; the southern portion of the Holocene Belize shelf is a modern example of an intrashelf basin. Two types of intrashelf basins are recognized. Coastal basins pass updip into coastal clastics of the craton with the basin primarily filled by fine clastics. Shelf basins occur on the outer part of the shelf, are surrounded by shallow-water carbonate facies, and are filled by peloidal lime mud, pelagics, and argillaceous carbonates. Intrashelf basins are commonly the site of organic-rich, source-bed deposition, resulting in the close proximity of source beds and reservoir facies that may fringe or overlie the basin. Examples of hydrocarbon-charged reservoirs that were sourced by an intrashelf basin include the Miocene Bombay High field, offshore India; the giant Jurassic (Arab-D) and Cretaceous (Shuaiba) reservoirs of the Arabian Shelf; the Lower Cretaceous Sunniland trend, South Florida basin; and the Permian-Pennsylvanian reservoirs surrounding the Tatum basin in southeastern New Mexico.

  3. A comparison of sediment deposition in two adjacent floodplains of the River Adour in southwest France.

    PubMed

    Brunet, R-C; Brian Astin, K

    2008-09-01

    Two floodplains within the catchment of the River Adour (SW France) have been examined in order to analyse spatio-temporal variations in discharge and suspended matter flux. Both floodplain zones were found to be excellent sites for the interception of suspended sediment. The narrow riparian vegetative strips (RVS) within each zone were found to retain 92-98% of the sediment trapped within the floodplain during each of three separate flood events. The precise level of sediment deposited within the floodplain was found to be dependent on micro-topographical features and the nature of the vegetation: the wooded areas within the RVS being particularly effective at trapping sediment. Mean masses of sediment collected in the flood plains ranged from 75 kg m(-2) in the RVS to 0.02 kg m(-2) in the areas of the floodplain inundated by back-up flows. Using data on discharge and sediment fluxes within the catchment gathered over a period of 25 years it is possible to discern how hydroclimatic fluctuations have affected the watershed with periods of sediment retention within the floodplain zones alternating with periods of sediment export. Anthropogenic activity, involving river management, including the cutting of meanders, the construction of dykes for flood prevention and the use of water for agricultural purposes, has also had a major impact during this period, particularly in the downstream areas of the catchment.

  4. Depositional systems and hydrocarbon resource potential of the Pennsylvanian system, Palo Duro and Dalhart Basins, Testas Panhandle. Geological Circular 80-8

    SciTech Connect

    Dutton, S.P.

    1980-01-01

    Pennsylvanian clastic and carbonate strata were deposited in a variety of environments within the Palo Duro Basin. Maximum accumulation (totalling 750 m or 2400 ft) occurred along a northwest-southeast axis. Major facies include fan-delta sandstone and conglomerate, shelf and shelf-margin carbonate, deltaic sandstone and shale, and basinal shale and fine-grained sandstone. Erosion of Precambrian basement in the adjacent Amarillo and Sierra Grande Uplifts supplied arkosic sand (granite wash) to fan deltas along the northern margin of the basin. Distal fan-delta sandstones grade laterally and basinward into shallow-shelf limestone. Deep basinal shales were deposited only in a small area immediately north of the Matador Arch. Increased subsidence deepened and enlarged the basin throughout late Pennsylvanian time. Ultimately, the basin axis trended east-west with a narrow northwest extension. A carbonate shelf-margin complex having 60 to 120 m (200 to 400 ft) of depositional relief developed around the basin margin. The eastern shelf margin remained stationary, but the western shelf margin retreated landward throughout late Pennsylvanian time. Porous, dolomitized limestone occurs in a belt 16 to 32 km (10 to 20 mi) wide along the shelf margin. High-constructive elongate deltas prograded into the Palo Duro Basin from the east during late Pennsylvanian time. Prodelta mud and thin turbidite sands entered the basin through breaks in the eastern carbonate shelf margin. Potential hydrocarbon reservoirs re shelf-margin dolomite, fan-delta sandstone, and high-constructive delta sandstone. Basinal shales are fair to good hydrocarbon source rocks on the basis of total organic carbon content. Kerogen color and vitrinite reflectance data indicate that source beds may have reached the early stages of hydrocarbon maturation.

  5. Sedimentation and tectonics in the southern Bida Basin, Nigeria: depositional response to varying tectonic context

    SciTech Connect

    Braide, S.P. )

    1990-05-01

    The Upper Cretaceous Bida basin of central Nigeria is sandwiched between the Precambrian schist belts of the Northern Nigerian massif and the West African craton. Of interest is the southern part of the basin, which developed in continental settings, because the facies architecture of the sedimentary fill suggests a close relation between sedimentation dynamics and basin margin tectonics. This relationship is significant to an understanding of the basin's origin, which has been controversial. A simple sag and rift origin has been suggested, and consequently dominated the negative thinking on the hydrocarbon prospects of the basin which were considered poor. This detailed study of the facies indicates rapid basin-wide changes from various alluvial fan facies through flood-basin and deltaic facies to lacustrine facies. Paleogeographic reconstruction suggests lacustrine environments were widespread and elongate. Lacustrine environments occurred at the basin's axis and close to the margins. This suggests the depocenter must have migrated during the basin's depositional history and subsided rapidly to accommodate the 3.5-km-thick sedimentary fill. Although distinguishing pull-apart basins from rift basins, based solely on sedimentologic grounds, may be difficult, the temporal migration of the depocenter, as well as the basin architecture of upward coarsening cyclicity, show a strong tectonic and structural overprint that suggests a tectonic framework for the Southern Bida basin similar in origin to a pull-apart basin.

  6. Hydrothermal zebra dolomite in the Great Basin, Nevada--attributes and relation to Paleozoic stratigraphy, tectonics, and ore deposits

    USGS Publications Warehouse

    Diehl, S.F.; Hofstra, A.H.; Koenig, A.E.; Emsbo, P.; Christiansen, W.; Johnson, Chad

    2010-01-01

    discordant HZD is proximal to high-angle structures at the carbonate platform margin, such as strike-slip and growth faults and dilational jogs. Fabric-selective replacement and dissolution features (e.g., collapse breccias, voids with geopetal textures) are common, with remaining void space lined with light-colored dolomite crystals that exhibit zoning under cathodoluminescence. Zoned crystals usually contain tiny ( ~70 degrees C. The oxygen isotopic compositions of HZD are consistent with formation temperatures of 50-150 degrees C requiring brine circulation to depths of 2-5 km, or more. The few HZD occurrences with the highest concentrations of metals (especially Fe, Mn, and Zn) and the largest isotopic shifts are closely associated with Sedex or MVT deposits known to have formed from hotter brines (e.g., Th > 150-250 degrees C). These relationships permit that HZD formed at about the same time as dolostone, from brines produced by the evaporation of seawater during arid paleoclimates at equatorial paleolatitudes. Both dolostone and HZD may have formed as basinal brines, which migrated seaward from evaporative pans on the platform, with dolostone forming at low temperatures along shallow migration pathways through permeable limestones, and HZD forming at high temperatures along deeper migration pathways through basal aquifers and dilatant high-angle faults. The small MVT deposits were chemical traps where hot brines encountered rocks or fluids containing reduced sulfur. The abundant Sedex deposits mark sites where hot brine discharged at the seafloor in adjacent basins. Thus the distribution of HZD may map deep migration pathways and upflow zones between eastern shallow marine facies, where evaporative brine could have been generated, and western Sedex deposits, where heated brines discharged along faults into platform margin, slope, and basin facies. The small size and scarcity of Pb-Zn depos

  7. Middle Cenozoic depositional, tectonic, and sea level history of southern San Joaquin basin, California

    SciTech Connect

    Decelles, P.G.

    1988-11-01

    As a prolific producer of hydrocarbons, the San Joaquin basin in south-central California has been the subject of geological research since the late nineteenth century. Much of this research has focused on the subsurface Eocene to lower Miocene succession because of its attractive reservoir potential. Although seismic and well-log data are available in profuse quantities, the complex sedimentary architecture of the basin fill, the application of local and inconsistent stratigraphic nomenclature, and the inherent limitations of subsurface data have led to much confusion concerning the middle Cenozoic history of the basin. This paper presents a sedimentological analysis of the depositional systems in the Eocene to lower Miocene strata of the San Emigdio and Tehachapi Mountains. The various depositional systems are considered within the contexts of encompassing depositional sequences to reconstruct the middle Cenozoic depositional, tectonic, and sea level history of the southern San Joaquin basin. 14 figures, 1 table.

  8. Overview of mine drainage geochemistry at historical mines, Humboldt River basin and adjacent mining areas, Nevada. Chapter E.

    USGS Publications Warehouse

    Nash, J. Thomas; Stillings, Lisa L.

    2004-01-01

    Reconnaissance hydrogeochemical studies of the Humboldt River basin and adjacent areas of northern Nevada have identified local sources of acidic waters generated by historical mine workings and mine waste. The mine-related acidic waters are rare and generally flow less than a kilometer before being neutralized by natural processes. Where waters have a pH of less than about 3, particularly in the presence of sulfide minerals, the waters take on high to extremely high concentrations of many potentially toxic metals. The processes that create these acidic, metal-rich waters in Nevada are the same as for other parts of the world, but the scale of transport and the fate of metals are much more localized because of the ubiquitous presence of caliche soils. Acid mine drainage is rare in historical mining districts of northern Nevada, and the volume of drainage rarely exceeds about 20 gpm. My findings are in close agreement with those of Price and others (1995) who estimated that less than 0.05 percent of inactive and abandoned mines in Nevada are likely to be a concern for acid mine drainage. Most historical mining districts have no draining mines. Only in two districts (Hilltop and National) does water affected by mining flow into streams of significant size and length (more than 8 km). Water quality in even the worst cases is naturally attenuated to meet water-quality standards within about 1 km of the source. Only a few historical mines release acidic water with elevated metal concentrations to small streams that reach the Humboldt River, and these contaminants and are not detectable in the Humboldt. These reconnaissance studies offer encouraging evidence that abandoned mines in Nevada create only minimal and local water-quality problems. Natural attenuation processes are sufficient to compensate for these relatively small sources of contamination. These results may provide useful analogs for future mining in the Humboldt River basin, but attention must be given to

  9. Groundwater quality in the shallow aquifers of the Tulare, Kaweah, and Tule Groundwater Basins and adjacent highlands areas, Southern San Joaquin Valley, California

    USGS Publications Warehouse

    Fram, Miranda S.

    2017-01-18

    Groundwater provides more than 40 percent of California’s drinking water. To protect this vital resource, the State of California created the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The Priority Basin Project of the GAMA Program provides a comprehensive assessment of the State’s groundwater quality and increases public access to groundwater-quality information. The shallow aquifers of the Tulare, Kaweah, and Tule groundwater basins and adjacent highlands areas of the southern San Joaquin Valley constitute one of the study units being evaluated.

  10. Hydrogeologic characteristics of the alluvial aquifer and adjacent deposits of the Fountain Creek valley, El Paso County, Colorado

    USGS Publications Warehouse

    Radell, Mary Jo; Lewis, Michael E.; Watts, Kenneth R.

    1994-01-01

    The alluvial aquifer in Fountain Creek Valley between Colorado Springs and Widefield is the source for several public-supply systems. Because of the importance of this aquifer, defining aquifer boundaries, areas where underflow occurs, and where Fountain Creek is hydraulically connected to the aquifer will greatly add to the understanding of the alluvial aquifer and management of the public- supply systems. Bedrock altitude, water-table altitude for October 1991, saturated thickness for October 1991, selected hydrogeologic sections in the alluvial aquifer and adjacent deposits of the Fountain Creek Valley, and estimated underflow rates are mapped or tabulated for the area between Colorado Springs and Widefield, Colorado. Results from test drilling indicate that the bedrock surface is highly irregular and that several ridges and buried channels exist in the study area. These features affect the direction of ground-water flow on a local scale. In places, a shale ridge prevents exchange of water between Fountain Creek and the aquifer. Generally, ground water flowed toward Fountain Creek during the study (June 1991 to September 1992) in response to relatively high hydraulic heads in the aquifer and the steep gradients on the boundaries of the study area. Water levels, which were measured monthly, varied little during the study, except in areas near pumping wells or adjacent to Fountain Creek. Hydraulic-conductivity values, estimated from 30 bail tests in wells completed in the alluvial aquifer, were used to determine underflow across the saturated boundaries of the alluvial aquifer. Estimated hydraulic-conductivity values range from 1 to about 1,300 feet per day; the larger values occur in the buried channel of the alluvial aquifer and the smaller values occur near the boundaries of the saturated alluvium. Estimated underflow into the study area exceeded underflow out of the study area by about 10 times. Gain-loss investigations along Fountain Creek indicated that the

  11. The curious case of Hermodice carunculata (Annelida: Amphinomidae): evidence for genetic homogeneity throughout the Atlantic Ocean and adjacent basins.

    PubMed

    Ahrens, Joseph B; Borda, Elizabeth; Barroso, Rômulo; Paiva, Paulo C; Campbell, Alexandra M; Wolf, Alexander; Nugues, Maggy M; Rouse, Greg W; Schulze, Anja

    2013-04-01

    Over the last few decades, advances in molecular techniques have led to the detection of strong geographic population structure and cryptic speciation in many benthic marine taxa, even those with long-lived pelagic larval stages. Polychaete annelids, in particular, generally show a high degree of population divergence, especially in mitochondrial genes. Rarely have molecular studies confirmed the presence of 'cosmopolitan' species. The amphinomid polychaete Hermodice carunculata was long considered the sole species within its genus, with a reported distribution throughout the Atlantic and adjacent basins. However, recent studies have indicated morphological differences, primarily in the number of branchial filaments, between the East and West Atlantic populations; these differences were invoked to re-instate Hermodice nigrolineata, formerly considered a junior synonym of H. carunculata. We utilized sequence data from two mitochondrial (cytochrome c oxidase subunit I, 16S rDNA) markers and one nuclear (internal transcribed spacer) marker to examine the genetic diversity of Hermodice throughout its distribution range in the Atlantic Ocean, including the Mediterranean Sea, the Caribbean Sea, the Gulf of Mexico and the Gulf of Guinea. Our analyses revealed generally low genetic divergences among collecting localities and between the East and West Atlantic, although phylogenetic trees based on mitochondrial data indicate the presence of a private lineage in the Mediterranean Sea. A re-evaluation of the number of branchial filaments confirmed differences between East and West Atlantic populations; however, the differences were not diagnostic and did not reflect the observed genetic population structure. Rather, we suspect that the number of branchial filaments is a function of oxygen saturation in the environment. Our results do not support the distinction between H. carunculata in the West Atlantic and H. nigrolineata in the East Atlantic. Instead, they re-affirm the

  12. Modern nonmarine evaporite deposition, Quaidam basin, China: An overview

    SciTech Connect

    Lowenstien, T.K.; Casas, E.; Schubel, K.A. ); Spencer, R.J. ); Pengxi, Zhang )

    1991-03-01

    Dabusun Lake (200 km{sup 2}) is a shallow ({lt}1 m) perennial saline lake in the high altitude Qaidam basin (120,000 km{sup 2}) of western China. It is underlain by {gt}40 m of salt and siliciclastic sediments ({approximately}54,000 years old). Petrographic features in two 50 m cores (chevron halite, halite cumulates, rafts, and siliciclastic mud, minor solution and no subaerial exposure features except in the top meter) indicate continuous shallow perennial lake conditions. The chemical composition of fluid inclusions trapped in halite crystals show lakewaters have generally undergone progressive concentration to the present. Modern Dabusun Lake is chemically uniform (Na-Mg-Cl-rich), nonstratified, and at or near halite saturation. Evaporites accumulate in zones on the restricted lake margins as halite (cumulate and raft layers with rippled surfaces and chevron mounds), halite + carnallite (KCl{center dot}MgCl{sub 2}{center dot}6H{sub 2}O), and finally carnallite (ephemeral fine-grained crystal mush). The carnallite zone merges with a 25 m wide shoreline facies, highlighted by a 1 m wide zone of halite ooids/pisoids that border a 20-30 cm tall overhanging salt crust (1967 shoreline). Lower lake levels since that time have produced vadose diagenetic features in the shoreline halites including: pendant cements, meniscus cements, halite 'popcorn,' and solution voids with muddy geopetal fills. A large flood (July-September 1989) expanded Dabusun Lake to 800 km{sup 2}, and dissolved all surface carnallite deposits. Diagenetic carnallite cements, formed by downward migration and cooking of carnallite saturated surface brines, however, remain in the subsurface to depths of 13 m. These potash mineral cements are similar in texture to many ancient potash evaporites.

  13. Teasing Apart the Effects of Atmospheric Nitrogen Deposition from Grazing and Drought in Vernal Pool Wetlands and Adjacent Grassland

    NASA Astrophysics Data System (ADS)

    Fogel, M. L.; Araiza, D. N.; Nakamoto, B. J.; Vega, M. C.; Bradley, C. J.; Swarth, C. W.

    2014-12-01

    The remaining vernal pools flanking California's Central Valley may be protected from development, but they are not pristine environments. At UC Merced's Vernal Pools and Grassland Reserve, dairy cattle grazing is a fact of life, needed to keep non-native grasses from encroaching on and dominating these low lying, ephemeral pools. In addition to grazing, atmospheric deposition of nitrogen from adjacent agricultural farms and dairies has affected the biogeochemical cycling here, in particular because the area has never been ploughed and is essentially a terminal, interior catchment with almost no outputs. For the past two years, the region has been subjected to extreme drought resulting in altered patterns in vernal pool development and nutrient exchange. We are using stable nitrogen, carbon, and hydrogen isotopes in organic and inorganic reservoirs to understand which of the three stressors (e.g. N loading, grazing, or drought) affects the ecosystem functioning the most. Simple measurements of residual dry matter (the rancher's standard) coupled with soil analyses and plant distribution, isotopic composition, and productivity will be presented at a landscape scale. Atmospheric deposition, as rain in winter and early spring and as dust in summer and fall, delivers substantial ammonium and nitrate to the Reserve and could be traced back to nearby hotspots, as well as from major storm systems. Concentrations and compositions of N in precipitation were highly variable depending on when the last storm event had occurred. Ammonia/ammonium in rainwater ranged from δ15N= -24 to +7‰, probably explaining the large range in the δ15N of plant tissues collected in winter/spring (-4.3 to +10.9‰,) and that of extractable ammonium from surface soils (δ15N = -7 to +13‰). Interior grassland and vernal pool ecosystems, with substantial inputs and little to no outputs, host biogeochemical processes that amplify heterogeneity on relative small scales.

  14. Drainage basin morphometry controls on the active depositional area of debris flow fans

    NASA Astrophysics Data System (ADS)

    Mihir, Monika; Wasklewicz, Thad; Malamud, Bruce

    2015-04-01

    A majority of the research on understanding the connection between alluvial fans and drainage basins to date has focused on coarse-scale relations between total fan area and drainage basin area. Here we take a new approach where we assess relationships between active fan depositional area and drainage basin morphometry using 52 debris flow fans (32 from the White Mountains and 20 from the Inyo Mountains) on the eastern side of Owens Valley, California, USA. The boundaries for fans, drainage basin and active depositional areas were delineated from 10m digital elevation models and 1 m aerial photographs. We examined the relationships between the normalised active depositional area of the fan (Afad/Af, where Afad is the fan active depositional area and Af the entire fan area) and the following four variables for drainage basin: (i) area (Adb), (ii) total stream length (Ls), (iii) relief (BHH), (iv) roughness (R). We find a statistically significant (r2 > 0.40) inverse power-law relationship between recent sediment contribution to the fan and drainage basin area (Afad/Af = 0.29Adb-0.167) drainage network length (Afad/Af = 0.39Ls-0.161) and basin relief (Afad/Af = 3.90BHH-0.401), and a statistically weak (r2 = 0.22) inverse power law with basin roughness (Afad/Af = 0.32R0.5441). Drainage basin size combined with other morphometric variables may largely determine efficiency in sediment transport and delivery to the fan surface. A large proportion of the total fan area of smaller fans are flooded by debris flow indicating less sediment storage in the drainage basins and greater efficiency in sediment delivery. The findings signify the importance of coarse-scale relationships to both long- and short-term fan evolution.

  15. Atmospheric nitrogen in the Mississippi River Basin - Amissions, deposition and transport

    USGS Publications Warehouse

    Lawrence, G.B.; Goolsby, D.A.; Battaglin, W.A.; Stensland, G.J.

    2000-01-01

    Atmospheric deposition of nitrogen has been cited as a major factor in the nitrogen saturation of forests in the north-eastern United States and as a contributor to the eutrophication of coastal waters, including the Gulf of Mexico near the mouth of the Mississippi River. Sources of nitrogen emissions and the resulting spatial patterns of nitrogen deposition within the Mississippi River Basin, however, have not been fully documented. An assessment of atmospheric nitrogen in the Mississippi River Basin was therefore conducted in 1998-1999 to: (1) evaluate the forms in which nitrogen is deposited from the atmosphere; (2) quantify the spatial distribution of atmospheric nitrogen deposition throughout the basin; and (3) relate locations of emission sources to spatial deposition patterns to evaluate atmospheric transport. Deposition data collected through the NADP/NTN (National Atmospheric Deposition Program/National Trends Network) and CASTNet (Clean Air Status and Trends Network) were used for this analysis. NO(x) Tier 1 emission data by county was obtained for 1992 from the US Environmental Protection Agency (Emissions Trends Viewer CD, 1985-1995, version 1.0, September 1996) and NH3 emissions data was derived from the 1992 Census of Agriculture (US Department of Commerce. Census of Agriculture, US Summary and County Level Data, US Department of Commerce, Bureau of the Census. Geographic Area series, 1995:1b) or the National Agricultural Statistics Service (US Department of Agriculture. National Agricultural Statistics Service Historical Data. Accessed 7/98 at URL, 1998. http://www.usda.gov/nass/pubs/hisdata.htm). The highest rates of wet deposition of NO3- were in the north-eastern part of the basin, downwind of electric utility plants and urban areas, whereas the highest rates of wet deposition of NH4+ were in Iowa, near the center of intensive agricultural activities in the Midwest. The lowest rates of atmospheric nitrogen deposition were on the western (windward

  16. Depositional setting of Ordovician and Cambrian rocks in central Appalachian basin along a section from Morrow County, Ohio, to Calhoun County, West Virginia

    SciTech Connect

    Ryder, R.T.

    1988-08-01

    A 200-mi (320 km) long restored stratigraphic section from Morrow County, Ohio, to Calhoun County, West Virginia, contrasts Ordovician and Cambrian rocks deposited on a relatively stable shelf with those deposited in rift and postrift basins. Lithologic data are from commercial logs and from detailed descriptions of cores in five of the nine drill holes used to construct the section. Particularly instructive was the 2,352 ft (717 m) of core from the Hope Natural Gas 9634 Power Oil basement test in Wood County, West Virginia. Rift basin deposits are dominated by medium to dark-gray argillaceous limestone, argillaceous siltstone, and by green-gray to black shale of probable subtidal origin. Dolomite is the dominant rock type in the postrift basin and adjacent stable shelf deposits. The upper part of the postrift sequence, composed of the Middle Ordovician Black River Limestone, the Middle Ordovician Trenton Limestone, and Middle and Upper Ordovician Antes (Utica) Shale with a high organic content, represents deposition in gradually deepening water on an open shelf.

  17. Clastic depositional styles and reservoir potential of Mediterranean basins

    SciTech Connect

    Bouma, A.H. )

    1990-05-01

    A variety of tectonic styles and activities throughout the late Mesozoic and younger epochs influenced sediment transport to the Mediterranean basins and, consequently, the approach needed to finding reservoir-type clastics. The style of the present-day basins varies from west to east, with large basinal depressions and continental rises in the western province, more elongate shapes in the central area, and numerous small basins and trenches in the eastern Mediterranean. In general terms, all these basins contain a similar fill: a deep-water sequence older than late Miocene, overlain by upper Miocene evaporites, and topped by Pliocene-Quaternary clastics. The exact type of fill depends on several factors, including proximity to the sediment source, climatic conditions, subsidence and tectonic activity, and tectono-eustatic or glacio-eustatic oscillations. Investigations on many of the clastic reservoirs in Mediterranean basins should emphasize submarine fans. The modern Mediterranean Sea contains several mid-sized fans (Rhone, Ebro, Valencia, and Nile fans) and many small ones (e.g., Crati Fan). There are several well-studied Tertiary subsurface and outcropping turbidite systems. The concept of deep-water marine sands, and many of the initial studies, began with some of the now classic outcrops in Italy, France, and Spain. A well-integrated study of both modern and ancient turbidite series is needed to construct basic exploration models for the Mediterranean region. 9 figs., 1 tab.

  18. Depositional and structural styles in Chad basin of northeastern Nigeria

    SciTech Connect

    Avbovbo, A.A.; Ayoola, E.O.; Osahon, G.A.

    1986-12-01

    Seismic reflection data in the Maiduguri area of the Chad basin reveal a significant juxtaposition of faults and folds, the primary structural orientation of which is northeast-southwest and parallel to the surface structural pattern in the contiguous Benue trough. The faults in the basin consist of both basement-involved faults and detached faults. The folds are simple symmetrical structures, restricted to the deeper parts of the basin. Concomitant compressive structures are notably scarce. The structural pattern is complicated further by the presence of intrusions that are presumed to be the subsurface extension of volcanic outcrops that rim the southeastern part of the Maiduguri subbasin. Seismic reflection data also reveal distinguishable seismic sequences that correlate with the established stratigraphic sequence of the basin. The apparent structure and the seismically derived stratigraphy suggest a rift origin for the basin. Furthermore, the seismic stratigraphy, sedimentologic implications, and seismically determined structural features suggest that the Maiduguri area of the Chad basin has good prospects for hydrocarbon plays in Cretaceous rocks, with high potentials for both structural and stratigraphic traps. 9 figures.

  19. Tephrostratigraphic investigations of the Late Pleistocene-Holocene deposits in the northwestern Pacific Ocean and adjacent seas (Okhotsk and Bering)

    NASA Astrophysics Data System (ADS)

    Derkachev, A.; Nikolaeva, N.; Portnyagin, M.; Ponomareva, V.; Gorbarenko, S.; Malakhov, M.; Nuernberg, D.; van den Bogaard, C.; Sakamoto, T.; Lv, H.

    2012-12-01

    Ash layers (tephra) in both continental and marine deposits bear information about history and nature of volcanic eruptions which could influence climate, processes of sedimentation, and even cause ecological disasters. Tephra layers of Quaternary age have been identified in various marine and continental deposits within the northwestern part of transition zone from the Asian continent to the Pacific Ocean. Tephras from the areas adjacent to the Japanese Islands are better studied while those from the areas farther north including Okhotsk and Bering Seas have received less attention until recently. More than 40 sediment cores were obtained during numerous expeditions performed by Russian, German, Japanese and Chinese scientists during the last fifteen years. We have identified and sampled a total of 74 tephra layers and lenses from these cores including 22 layers in the Okhotsk Sea, 14 layers in the Bering Sea, and 38 layers - in the northwestern Pacific (Kronotsky Bay and Meiji Seamount). Ages of tephra layers have been estimated based on age-depth models for the cores developed in the result of litho- and biostratigraphic studies, paleomagnetic and oxygen-isotope research, and 14C dating. Tephra from all these layers have been characterized based on morphology of glass shards, optical properties (refractive indices), and chemical composition of glass (major and trace elements) and minerals (major elements). About 3500 precise and consistent electron probe and ~200 LA-ICP-MS analyses of volcanic glasses and 1200 electron probe analyses of minerals comprise the core of our new data base. Processing of these data has allowed us to correlate a number of tephra layers between the cores in each of the studied regions. Several tephra layers have been correlated between the Bering Sea and Pacific cores. These results permit direct comparisons of the paleoceanological records over the vast area in the northwestern Pacific domain. Studied tephra layers form the basis of

  20. Quantity and location of groundwater recharge in the Sacramento Mountains, south-central New Mexico (USA), and their relation to the adjacent Roswell Artesian Basin

    NASA Astrophysics Data System (ADS)

    Rawling, Geoffrey C.; Newton, B. Talon

    2016-06-01

    The Sacramento Mountains and the adjacent Roswell Artesian Basin, in south-central New Mexico (USA), comprise a regional hydrologic system, wherein recharge in the mountains ultimately supplies water to the confined basin aquifer. Geologic, hydrologic, geochemical, and climatologic data were used to delineate the area of recharge in the southern Sacramento Mountains. The water-table fluctuation and chloride mass-balance methods were used to quantify recharge over a range of spatial and temporal scales. Extrapolation of the quantitative recharge estimates to the entire Sacramento Mountains region allowed comparison with previous recharge estimates for the northern Sacramento Mountains and the Roswell Artesian Basin. Recharge in the Sacramento Mountains is estimated to range from 159.86 × 106 to 209.42 × 106 m3/year. Both the location of recharge and range in estimates is consistent with previous work that suggests that ~75 % of the recharge to the confined aquifer in the Roswell Artesian Basin has moved downgradient through the Yeso Formation from distal recharge areas in the Sacramento Mountains. A smaller recharge component is derived from infiltration of streamflow beneath the major drainages that cross the Pecos Slope, but in the southern Sacramento Mountains much of this water is ultimately derived from spring discharge. Direct recharge across the Pecos Slope between the mountains and the confined basin aquifer is much smaller than either of the other two components.

  1. On Restoring Sedimentary Basins for Post-Depositional Deformation - Paleozoic Basins of the Central Andes

    NASA Astrophysics Data System (ADS)

    Bahlburg, H.

    2015-12-01

    The reconstruction and interpretation of sedimentary basins incorporated into folded and thrusted mountain belts is strongly limited by the style and intensity of shortening. This problem is exacerbated if deformation is polyphasic as is the case for the Paleozoic basins in the central Andes. Some of these have been deformed by folding and thrusting during at least 3 events in the Late Ordovician, the Late Paleozoic and Cenozoic. A realistic reconstruction of the original basin dimensions and geometries from outcrops and maps appears to be almost impossible. We present results of a stepwise reconstruction of the Paleozoic basins of the central Andes by restoring basin areas and fills accounting for crustal shortening. The structurally most prominent feature of the central Andes is the Bolivian Orocline which accomodated shortening in the last 45 Ma on the order of between 300 and 500 km. In a first step basins were restored by accounting for Cenozoic rotation and shortening by deconvolving the basins using an enhanced version of the oroclinal bending model of Ariagada et al. (2008). Results were then restored stepwise for older deformation. Constraints on these subsequent steps are significantly poorer as values of shortening can be derived only from folds and thusts apparent in outcrops. The amount of shortening accomodated on unexposed and therefore unknown thrusts can not be quantified and is a significant source of error very likely leading to an underestimation of the amount of shortening. Accepting these limitations, basin restoration results in an increase in basin area by ≥100%. The volumes of stratigraphically controlled basin fills can now be redistributed over the wider, restored area, translating into smaller rates of accumulation and hence required subsidence. The restored rates conform to those of equivalent modern basin settings and permit a more realistic and actualistic analysis of subsidence drivers and the respective tectonic framework.

  2. Three depositional states and sedimentary processes of the western Taiwan foreland basin system

    NASA Astrophysics Data System (ADS)

    Lin, Yi-Jung; Wu, Pei-Jen; Yu, Ho-Shing

    2010-05-01

    The western Taiwan foreland basin formed during the Early Pliocene as the flexural response to the loading of Taiwan orogen on the Eurasian plate. What makes Taiwan interesting is the oblique collision, which allows the foreland basin to be seen at different stages in its evolution at the present day. Due to oblique arc-continent collision from north to south, the western Taiwan foreland basin has evolved into three distinct subbasins: an over-filled basin proximal to the Taiwan orogen, mainly distributed in the Western Foothills and Coastal Plain provinces, a filled basin occupying the shallow Taiwan Strait continental shelf west of the Taiwan orogen and an under-filled basin distal to the Taiwan orogen in the deep marine Kaoping Slope offshore southwest Taiwan, respectively. The over-filled depositional phase is dominated by fluvial environments across the structurally controlled piggy-back basins. The filled depositional state in the Taiwan Strait is characterized by shallow marine environments and is filled by Pliocene-Quaternary sediments up to 4,000 m thick derived from the Taiwan orogen with an asymmetrical and wedge-shaped cross section. The under-filled depositional state is characteristic of deep marine environments in the wedge-top basins accompanied by active structures of thrust faults and mud diapers. Sediments derived from the Taiwan orogen have progressively filled the western Taiwan foreland basin across and along the orogen. Sediment dispersal model suggests that orogenic sediments derived from oblique dischronous collisional highlands are transported in two different ways. Transport of fluvial and shallow marine sediments is perpendicular to hill-slope and across-strike in the fluvial and shallow marine environments proximal to the orogen. Fine-grained sediments mainly longitudinally transported into the deep marine environments distal to the orogen. The present sedimentary processes in the over-filled basin on land are dominated by fluvial

  3. Water-level data for the Albuquerque Basin and adjacent areas, central New Mexico, period of record through September 30, 2012

    USGS Publications Warehouse

    Beman, Joseph E.

    2013-01-01

    The Albuquerque Basin, located in central New Mexico, is about 100 miles long and 25-40 miles wide. The basin is defined as the extent of consolidated and unconsolidated deposits of Tertiary and Quaternary age that encompasses the structural Rio Grande Rift within the basin. Drinking-water supplies throughout the basin were obtained solely from groundwater resources until December 2008, when surface water from the Rio Grande began being treated and integrated into the system. A population increase of about 20 percent in the basin from 1990 to 2000 and a 22 percent increase from 2000 to 2010 resulted in an increased demand for water. An initial network of wells was established by the U.S. Geological Survey (USGS) in cooperation with the City of Albuquerque from April 1982 through September 1983 to monitor changes in groundwater levels throughout the basin. This network consisted of 6 wells with analog-to-digital recorders and 27 wells where water levels were measured monthly in 1983. Currently (2012), the network consists of 126 wells and piezometers. (A piezometer is a specialized well open to a specific depth in the aquifer, often of small diameter and nested with other piezometers open to different depths.) The USGS, in cooperation with the Albuquerque Bernalillo County Water Utility Authority (ABCWUA), currently (2012) measures and reports water levels from the 126 wells and piezometers in the network; this report presents water-level data collected by USGS personnel at those 126 sites through water year 2012.

  4. Water-level data for the Albuquerque Basin and adjacent areas, central New Mexico, period of record through September 30, 2010

    USGS Publications Warehouse

    Beman, Joseph E.

    2011-01-01

    The Albuquerque Basin, located in central New Mexico, is about 100 miles long and 25-40 miles wide. The basin is defined as the extent of consolidated and unconsolidated deposits of Tertiary and Quaternary age that encompasses the structural Rio Grande Rift within the basin. Drinking-water supplies throughout the basin were obtained solely from groundwater resources until December 2008, when surface water from the Rio Grande began being treated and integrated into the system. An increase of about 20 percent in the basin human population from 1990 to 2000 and about a 22 percent increase from 2000 to 2010 also resulted in an increased demand for water. A network of wells was established by the U.S. Geological Survey in cooperation with the City of Albuquerque to monitor changes in groundwater levels throughout the basin from April 1982 through September 1983. This network consisted of 6 wells with analog-to-digital recorders and 27 wells where water levels were measured monthly in 1983. Currently (2010), the network consists of 124 wells and piezometers (a piezometer is a small-diameter subwell usually nested within a larger well). To better help the Albuquerque Bernalillo County Water Utility Authority manage water use, this report presents water-level data collected by U.S. Geological Survey personnel at those 124 sites through water year 2010.

  5. Water-level data for the Albuquerque Basin and adjacent areas, central New Mexico, period of record through September 30, 2011

    USGS Publications Warehouse

    Beman, Joseph E.

    2012-01-01

    The Albuquerque Basin, located in central New Mexico, is about 100 miles long and 25–40 miles wide. The basin is defined as the extent of consolidated and unconsolidated deposits of Tertiary and Quaternary age that encompasses the structural Rio Grande Rift within the basin. Drinking-water supplies throughout the basin were obtained solely from groundwater resources until December 2008, when surface water from the Rio Grande began being treated and integrated into the system. An increase of about 20 percent in the basin human population from 1990 to 2000 and of about 22 percent increase from 2000 to 2010 also resulted in an increased demand for water. A network of wells was established by the U.S. Geological Survey in cooperation with the City of Albuquerque from April 1982 through September 1983 to monitor changes in groundwater levels throughout the basin. This network consisted of 6 wells with analog-to-digital recorders and 27 wells where water levels were measured monthly in 1983. Currently (2011), the network consists of 126 wells and piezometers (a piezometer is a specialized well open to a specific depth in the aquifer and is often of small diameter and nested with other piezometers open to different depths). This report presents water-level data collected by U.S. Geological Survey personnel at those 126 sites through water year 2011 to better help the Albuquerque Bernalillo County Water Utility Authority manage water use.

  6. Water-level data for the Albuquerque Basin and adjacent areas, central New Mexico, period of record through September 30, 2013

    USGS Publications Warehouse

    Beman, Joseph E.

    2014-01-01

    The Albuquerque Basin, located in central New Mexico, is about 100 miles long and 25–40 miles wide. The basin is defined as the extent of consolidated and unconsolidated deposits of Tertiary and Quaternary age that encompasses the structural Rio Grande Rift within the basin. Drinking-water supplies throughout the basin were obtained solely from groundwater resources until December 2008, when treatment and distribution of surface water from the Rio Grande began. A population increase of about 20 percent in the basin from 1990 to 2000 and a 22-percent increase from 2000 to 2010 resulted in an increased demand for water. An initial network of wells was established by the U.S. Geological Survey (USGS) in cooperation with the City of Albuquerque from April 1982 through September 1983 to monitor changes in groundwater levels throughout the basin. This network consisted of 6 wells with analog-to-digital recorders and 27 wells where water levels were measured monthly in 1983. Currently (2013), the network consists of 123 wells and piezometers. (A piezometer is a specialized well open to a specific depth in the aquifer, often of small diameter and nested with other piezometers open to different depths.) The USGS, in cooperation with the Albuquerque Bernalillo County Water Utility Authority, currently (2013) measures and reports water levels from the 123 wells and piezometers in the network; this report presents water-level data collected by USGS personnel at those 123 sites through water year 2013.

  7. Sedimentary facies and depositional environments of early Mesozoic Newark Supergroup basins, eastern North America

    USGS Publications Warehouse

    Smoot, J.P.

    1991-01-01

    The early Mesozoic Newark Supergroup consists of continental sedimentary rocks and basalt flows that occupy a NE-trending belt of elongate basins exposed in eastern North America. The basins were filled over a period of 30-40 m.y. spanning the Late Triassic to Early Jurassic, prior to the opening of the north Atlantic Ocean. The sedimentary rocks are here divided into four principal lithofacies. The alluvial-fan facies includes deposits dominated by: (1) debris flows; (2) shallow braided streams; (3) deeper braided streams (with trough crossbeds); or (4) intense bioturbation or hyperconcentrated flows (tabular, unstratified muddy sandstone). The fluvial facies include deposits of: (1) shallow, ephemeral braided streams; (2) deeper, flashflooding, braided streams (with poor sorting and crossbeds); (3) perennial braided rivers; (4) meandering rivers; (5) meandering streams (with high suspended loads); (6) overbank areas or local flood-plain lakes; or (7) local streams and/or colluvium. The lacustrine facies includes deposits of: (1) deep perennial lakes; (2) shallow perennial lakes; (3) shallow ephemeral lakes; (4) playa dry mudflats; (5) salt-encrusted saline mudflats; or (6) vegetated mudflats. The lake margin clastic facies includes deposits of: (1) birdfoot deltas; (2) stacked Gilbert-type deltas; (3) sheet deltas; (4) wave-reworked alluvial fans; or (5) wave-sorted sand sheets. Coal deposits are present in the lake margin clastic and the lacustrine facies of Carnian age (Late Triassic) only in basins of south-central Virginia and North and South Carolina. Eolian deposits are known only from the basins in Nova Scotia and Connecticut. Evaporites (and their pseudomorphs) occur mainly in the northern basins as deposits of saline soils and less commonly of saline lakes, and some evaporite and alkaline minerals present in the Mesozoic rocks may be a result of later diagenesis. These relationships suggest climatic variations across paleolatitudes, more humid to the

  8. A new interpretation of deformation rates in the Snake River Plain and adjacent basin and range regions based on GPS measurements

    NASA Astrophysics Data System (ADS)

    Payne, S. J.; McCaffrey, R.; King, R. W.; Kattenhorn, S. A.

    2012-04-01

    Within the Northern Basin and Range Province, USA, we estimate horizontal velocities for 405 sites using Global Positioning System (GPS) phase data collected from 1994 to 2010. The velocities, together with geologic, volcanic, and earthquake data, reveal a slowly deforming region within the Snake River Plain in Idaho and Owyhee-Oregon Plateau in Oregon separated from the actively extending adjacent Basin and Range regions by shear. Our results show a NE-oriented extensional strain rate of 5.6 ± 0.7 × 10-9 yr-1 in the Centennial Tectonic Belt and an ˜E-oriented extensional strain rate of 3.5 ± 0.2 × 10-9 yr-1 in the Great Basin. These extensional rates contrast with the very low strain rate within the 125 km × 650 km region of the Snake River Plain and Owyhee-Oregon Plateau, which is indistinguishable from zero (-0.1 ± 0.4 × 10-9 yr-1). Inversions of the velocities with dyke-opening models indicate that rapid extension by dyke intrusion in volcanic rift zones, as previously hypothesized, is not currently occurring in the Snake River Plain. This slow internal deformation, in contrast to the rapidly extending adjacent Basin and Range regions, indicates shear along the boundaries of the Snake River Plain. We estimate right-lateral shear with slip rates of 0.3-1.4 mm yr-1 along the northwestern boundary adjacent to the Centennial Tectonic Belt and left-lateral oblique extension with slip rates of 0.5-1.5 mm yr-1 along the southeastern boundary adjacent to the Intermountain Seismic Belt. The fastest lateral shearing evident in the GPS occurs near the Yellowstone Plateau where strike-slip focal mechanisms and faults with observed strike-slip components of motion are documented. The regional velocity gradients are best fit by nearby poles of rotation for the Centennial Tectonic Belt, Snake River Plain, Owyhee-Oregon Plateau, and eastern Oregon, indicating that clockwise rotation is not locally driven by Yellowstone hotspot volcanism, but instead by extension to the

  9. The depositional setting of the Late Quaternary sedimentary fill in southern Bannu basin, Northwest Himalayan fold and thrust belt, Pakistan.

    PubMed

    Farid, Asam; Khalid, Perveiz; Jadoon, Khan Zaib; Jouini, Mohammed Soufiane

    2014-10-01

    Geostatistical variogram and inversion techniques combined with modern visualization tools have made it possible to re-model one-dimensional electrical resistivity data into two-dimensional (2D) models of the near subsurface. The resultant models are capable of extending the original interpretation of the data to depict alluvium layers as individual lithological units within the 2D space. By tuning the variogram parameters used in this approach, it is then possible to visualize individual lithofacies and geomorphological features for these lithologic units. The study re-examines an electrical resistivity dataset collected as part of a groundwater study in an area of the Bannu basin in Pakistan. Additional lithological logs from boreholes throughout the area have been combined with the existing resistivity data for calibration. Tectonic activity during the Himalayan orogeny uplifted and generated significant faulting in the rocks resulting in the formation of a depression which subsequently has been filled with clay-silt and dirty sand facies typical of lacustrine and flood plain environments. Streams arising from adjacent mountains have reworked these facies which have been eroded and replaced by gravel-sand facies along channels. It is concluded that the sediments have been deposited as prograding fan shaped bodies, flood plain, and lacustrine deposits. Clay-silt facies mark the locations of paleo depressions or lake environments, which have changed position over time due to local tectonic activity and sedimentation. The Lakki plain alluvial system has thus formed as a result of local tectonic activity with fluvial erosion and deposition characterized by coarse sediments with high electrical resistivities near the mountain ranges and fine sediments with medium to low electrical resistivities towards the basin center.

  10. Lithofacies and biofacies of mid-Paleozoic thermal spring deposits in the Drummond Basin, Queensland, Australia

    NASA Technical Reports Server (NTRS)

    Walter, M. R.; Desmarais, D.; Farmer, J. D.; Hinman, N. W.

    1996-01-01

    The Devonian to Carboniferous sinters of the Drummond Basin, Australia, are among the oldest well established examples of fossil subaerial hot springs. Numerous subaerial and subaqueous spring deposits are known from the geological record as a result of the occurrence of economic mineral deposits in many of them. Some are reported to contain fossils, but very few have been studied by paleobiologists; they represent an untapped source of paleobiological information on the history of hydrothermal ecosystems. Such systems are of special interest, given the molecular biological evidence that thermophilic bacteria lie near the root of the tree of extant life. The Drummond Basin sinters are very closely comparable with modern examples in Yellowstone National Park and elsewhere. Thirteen microfacies are recognisable in the field, ranging from high temperature apparently abiotic geyserite through various forms of stromatolitic sinter probably of cyanobacterial origin to ambient temperature marsh deposits. Microfossils in the stromatolites are interpreted as cyanobacterial sheaths. Herbaceous lycopsids occur in the lower temperature deposits.

  11. Geometric Reconstruction of Bedrock and Overlying Recent Deposits In An Intra-mountain Basin: The Clusone Basin (southern Alps, Italy)

    NASA Astrophysics Data System (ADS)

    Caielli, G.; Berra, F.

    Regione Lombardia (Direzione Generale Territorio e Urbanistica) and the National Research Council (CNR-IDPA Milano) acquired seismic reflection profiles in the Clu- sone basin (Middle Val Seriana, Southern Alps). In the study area, the bedrock is rep- resented by late Triassic carbonate units (Formazione di Castro, Dolomia Principale and coeval basinal facies, bordered northward by an important alpine fault) covered by a large amount of recent deposits that covers an area of more than 10 km2, with a maximum thickness of more than two hundreds meters, as documented by available well data. The aim of the seismic prospecting was to identify the sediments layering and the rock basement depth. The acquisition parameters were as follows: group in- terval 10 m; shot interval 5 m; geophone frequency 14 Hz; sample rate 1 ms; record length 2 s, energy source hydrapulse. The cable, with 120 channels, remained dur- ing all the experiment allowing reflection/refraction events acquisition. The data were processed by a standard procedure using PROMAX and SUNT5 processing codes. The statics were calculated starting from the refracted first arrivals using a two layer inversion based on least square optimisation. Standard seismic reflection processing was applied to obtain reflection images and it was integrated with seismic refraction data inversion. Seismic profiles allow to reconstruct both the main reflectors in the recent deposits and the geometry of the bedrock. The first results document a complex history in the drainage patterns of the Clusone basin, allowing to identify, in an intra- mountain basin, drainage directions that in some cases are different from the ones that can be observed today. The integration of well data and seismic profiles in this study of an intra-mountain basin allows on one side the identification of the bedrock geome- tries and, on the other, gives constrains for the reconstruction of the geomorphologic evolution of a sector of a mountain chain.

  12. 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.

  13. Distinct groundwater recharge sources and geochemical evolution of two adjacent sub-basins in the lower Shule River Basin, northwest China

    NASA Astrophysics Data System (ADS)

    Wang, Liheng; Dong, Yanhui; Xie, Yueqing; Song, Fan; Wei, Yaqiang; Zhang, Jiangyi

    2016-12-01

    Based on analysis of groundwater hydrogeochemical and isotopic data, this study aims to identify the recharge sources and understand geochemical evolution of groundwater along the downstream section of the Shule River, northwest China, including two sub-basins. Groundwater samples from the Tashi sub-basin show markedly depleted stable isotopes compared to those in the Guazhou sub-basin. This difference suggests that groundwater in the Tashi sub-basin mainly originates from meltwater in the Qilian Mountains, while the groundwater in the Guazhou sub-basin may be recharged by seepage of the Shule River water. During the groundwater flow process in the Tashi sub-basin, minerals within the aquifer material (e.g., halite, calcite, dolomite, gypsum) dissolve in groundwater. Mineral dissolution leads to strongly linear relationships between Na+ and Cl- and between Mg2++ Ca2+ and SO4 2- + HCO3 -, with stoichiometry ratios of approximately 1:1 in both cases. The ion-exchange reaction plays a dominant role in hydrogeochemical evolution of groundwater in the Guazhou sub-basin and causes a good linear relationship between (Mg2++ Ca2+)-(SO4 2- + HCO3 -) and (Na++ K+)-Cl- with a slope of -0.89 and also results in positive chloroalkaline indices CAI 1 and CAI 2. The scientific results have implications for groundwater management in the downstream section of Shule River. As an important irrigation district in Hexi Corridor, groundwater in the Guazhou sub-basin should be used sustainably and rationally because its recharge source is not as abundant as expected. It is recommended that the surface water should be used efficiently and routinely, while groundwater exploitation should be limited as much as possible.

  14. Water-level data for the Albuquerque Basin and adjacent areas, central New Mexico, period of record through September 30, 2009

    USGS Publications Warehouse

    Beman, Joseph E.; Torres, Leeanna T.

    2010-01-01

    The Albuquerque Basin, located in central New Mexico, is about 100 miles long and 25 to 40 miles wide. The basin is defined as the extent of consolidated and unconsolidated deposits of Tertiary and Quaternary age that encompass the structural Rio Grande Rift within the basin. Drinking-water supplies throughout the basin were obtained solely from groundwater resources until December 2008, when surface water from the Rio Grande began being treated and integrated into the system. An increase of about 20 percent in the population from 1990 to 2000 also resulted in an increased demand for water. A network of wells was established to monitor changes in groundwater levels throughout the basin from April 1982 through September 1983. This network consisted of 6 wells with analog-to-digital recorders and 27 wells where water levels were measured monthly in 1983. Currently (2009), the network consists of 131 wells and piezometers. This report presents water-level data collected by U.S. Geological Survey personnel at 123 sites through water year 2009. In addition, data from four wells (Sites 140, 147, 148, and 149) owned, maintained, and measured by Sandia National Laboratories and three from Kirtland Air Force Base (Sites 119, 125, and 126) are presented in this report.

  15. Water-Level Data for the Albuquerque Basin and Adjacent Areas, Central New Mexico, Period of Record Through September 30, 2008

    USGS Publications Warehouse

    Beman, Joseph E.

    2009-01-01

    The Albuquerque Basin, located in central New Mexico, is about 100 miles long and 25 to 40 miles wide. The basin is defined as the extent of consolidated and unconsolidated deposits of Tertiary and Quaternary age that encompass the structural Rio Grande Rift within the basin. Drinking-water supplies throughout the basin are currently (2008) obtained soley from ground-water resources. An increase of about 20 percent in the population from 1990 to 2000 also resulted in an increased demand for water. A network of wells was established to monitor changes in ground-water levels throughout the basin from April 1982 through September 1983. This network consisted of 6 wells with analog-to-digital recorders and 27 wells where water levels were measured monthly in 1983. Currently (2008), the network consists of 144 wells and piezometers. This report presents water-level data collected by U.S. Geological Survey personnel at 125 sites through water-year 2008. In addition, data from 19 wells (Sites 127-30, 132-134, 136, 138-142 and 144-149) owned, maintained, and measured by Sandia National Laboratories are presented in this report.

  16. A Model for Properties of Basin Ejecta Deposits and Secondary Crater Densities

    NASA Technical Reports Server (NTRS)

    Haskin, L. A.; McKinnon, W. B.; Moss, B. E.

    2001-01-01

    Ejecta scaling relationships, ballistic sedimentation, and ejecta fragment size distributions are used to give estimates of thicknesses of basin ejecta deposits, proportions of primary ejecta, and secondary crater diameters and surface densities. Additional information is contained in the original extended abstract.

  17. 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.

  18. Polish permian basin: Lithofacies traps for gas within the Rotliegende deposits as a new exploration potential

    SciTech Connect

    Karnkowski, P.H. )

    1993-09-01

    Rotliegende deposits are the most prospective reservoir gas rocks in the Polish Permian basin. Thirty years of their exploration have led to location of numerous gas fields in the upper-most part of these series, particularly in the area of the Fore-Sudetic monocline. Up to this time, exploration studies concentrated mainly on structural objects, and most of the structures were positive gas traps. Well and seismic data also indicate an occurrence of lithofacies gas traps; they occur mainly in the sandstone zones within the fanglomerates surrounding the Wolsztyn Ridge. When comparing the facies regularities in the known gas fields in the German Permian basin (interfingering sandstones and claystones) to the facies patterns of the Polish Permian basin, one may suspect similar exploration possibilities. These are the first promising results. Advances in analysis of the Rotliegende depositional systems will enable us to create a new exploration potential.

  19. A depositional model for late Jurassic Reef Building in the East Texas Basin

    SciTech Connect

    Norwood, E.M. ); Brinton, L. )

    1996-01-01

    The authors propose a depositional setting for the Upper Jurassic reef facies occurring at the upper Cotton Valley Lime, (Gilmer) sequence boundary in the East Texas Basin. The development of uncommonly thick, microbially bound reefal buildups positioned near the western margin of the basin was controlled by sea-level variations and gravity faulting, suggested to be concurrent. Gas bearing reefs occur as isolated features along faulted margins and have been successfully located using 3-D seismic. Reefs of this type and age appear to be rare in their occurrence worldwide. Structurally generated circumstances facilitated margin bypass of terrigenous clastics shed from the north and west. Protection from clastic influx contributed to conditions required for development of the 400 feet of reefal buildup penetrated by the Marathon Oil Company Poth No. 1 during early 1993. Core from this well provides insight into character, composition, and depositional setting of reefs along the western flank of the East Texas Basin during Late Jurassic time.

  20. A depositional model for late Jurassic Reef Building in the East Texas Basin

    SciTech Connect

    Norwood, E.M.; Brinton, L.

    1996-12-31

    The authors propose a depositional setting for the Upper Jurassic reef facies occurring at the upper Cotton Valley Lime, (Gilmer) sequence boundary in the East Texas Basin. The development of uncommonly thick, microbially bound reefal buildups positioned near the western margin of the basin was controlled by sea-level variations and gravity faulting, suggested to be concurrent. Gas bearing reefs occur as isolated features along faulted margins and have been successfully located using 3-D seismic. Reefs of this type and age appear to be rare in their occurrence worldwide. Structurally generated circumstances facilitated margin bypass of terrigenous clastics shed from the north and west. Protection from clastic influx contributed to conditions required for development of the 400 feet of reefal buildup penetrated by the Marathon Oil Company Poth No. 1 during early 1993. Core from this well provides insight into character, composition, and depositional setting of reefs along the western flank of the East Texas Basin during Late Jurassic time.

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

    SciTech Connect

    Sanford, R.F. )

    1990-11-01

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

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

    USGS Publications Warehouse

    Sanford, R.F.

    1990-01-01

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

  3. Carbonate replacement of lacustrine gypsum deposits in two Neogene continental basins, eastern Spain

    NASA Astrophysics Data System (ADS)

    Anadón, P.; Rosell, L.; Talbot, M. R.

    1992-07-01

    Bedded nonmarine gypsum deposits in the Miocene Teruel and Cabriel basins, eastern Spain, are partly replaced by carbonate. The Libros gypsum (Teruel Graben) is associated with fossiliferous carbonate wackestones and finely laminated, organic matter-rich mudstones which accumulated under anoxic conditions in a meromictic, permanent lake. The gypsum is locally pseudomorphed by aragonite or, less commonly, replaced by calcite. Low δ 13C values indicate that sulphate replacement resulted from bacterial sulphate reduction processes that were favoured by anacrobic conditions and abundant labile organic matter in the sediments. Petrographic evidence and oxygen isotopic composition suggest that gypsum replacement by aragonite occurred soon after deposition. A subsequent return to oxidising conditions caused some aragonite to be replaced by diagenetic gypsum. Native sulphur is associated with some of these secondary gypsum occurrences. The Los Ruices sulphate deposits (Cabriel Basin) contain beds of clastic and selenitic gypsum which are associated with limestones and red beds indicating accumulation in a shallow lake. Calcite is the principal replacement mineral. Bacterial sulphate reduction was insignificant in this basin because of a scarcity of organic matter. Stable isotope composition of diagenetic carbonate indicates that gypsum replacement occurred at shallow burial depths due to contact with dilute groundwaters of meteoric origin. Depositional environment evidently has a major influence upon the diagenetic history of primary sulphate deposits. The quantity of preserved organic matter degradable by sulphate-reducing bacteria is of particular importance and, along with groundwater composition, is the main factor controlling the mechanism of gypsum replacement by carbonate.

  4. Extensional fault-bend folding and synrift deposition: An example from the Central Sumatra basin, Indonesia

    SciTech Connect

    Shaw, J.H.; Hook, S.C.; Sitohang, E.P.

    1997-03-01

    We describe an analytical method for interpreting the geometry and structural history of asymmetric half grabens in rift basins with extensional fault-bend fold theory. Using seismic reflection profiles from the Central Sumatra basin and balanced forward models, we show how local variations in tectonic subsidence relative to deposition rates yield distinctive patterns of folded synrift strata and unconformities that record basin history. If the deposition rate exceeds the local subsidence rate, folded growth strata form upwardly narrowing kink bands that have been described previously as growth triangles. In contrast, if the deposition rate is less than or equals the local subsidence rate, growth strata are folded and truncated at the surface on half-graben margins. Subsequent increases in deposition rate relative to subsidence rate form angular unconformities near the half-graben margins. These unconformities develop without the necessity of erosion and are folded by continuing fault slip. Strata above and below the unconformities are concordant in the deeper parts of the half grabens. Thus, angular unconformities on half-graben margins are helpful for defining sequence boundaries that may reflect changes in deposition and tectonic subsidence rates. In addition, fault-bend fold interpretations yield fault geometry and measures of horizontal extension, both of which control three-dimensional half-graben geometry and accommodation space. We show how along-strike variations in fault geometry produce intrabasinal structures that may form prospective fair-ways or local depocenters.

  5. Controls on deposition of the St. Peter Sandstone (Middle-Late Ordovician), Michigan basin

    SciTech Connect

    Nadon, G.C.; Simo, A.; Byers, C.W.; Dott, R.H, Jr. )

    1991-08-01

    The St. Peter Sandstone (Middle-late Ordovician) of the Michigan basin represents an approximately 10-m.y. interval of clastic deposition in an otherwise carbonate-dominated Ordovician succession. This interval, up to 320 m thick, also coincides with a change in basin configuration from the nearly circular depocenter of the underlying Shakopee Formation to an east-west elongate trough situated west to Saginaw Bay. Interpretation of well logs and core from throughout the basin indicates that the clastics are composed of 20-25 sequences upper shoreface to tidal-flat environments. The sequences are interbedded with heavily bioturbated, shaly, lower shoreface sandstones (1-14 m thick) and, in the central and southeastern parts of the basin, with carbonate shales, stromatolites, and oolitic grain-stones (2-39 m thick). The eastern and southeastern margins of the basin contain the thickest carbonate accumulations. Hydrocarbons fields are located over structural highs formed by reactivation of basement structures. Detailed comparison of well logs within field shows that sedimentary cycles thin over the structures as a result of the local reduction in the formation of accommodation space by syndepositional movements on the faults. The presence of thick carbonates along the southeastern margin of the basin is a result of the combination of distance form the clastic source and the episodic formation of accommodation space by syndepositional normal faulting along the basin margin.

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

    USGS Publications Warehouse

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

    2006-01-01

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

  7. A new interpretation of deformation rates in the Snake River Plain and adjacent basin and range regions based on GPS measurements

    SciTech Connect

    S.J. Payne; R. McCaffrey; R.W. King; S.A. Kattenhorn

    2012-04-01

    We evaluate horizontal Global Positioning System (GPS) velocities together with geologic, volcanic, and seismic data to interpret extension, shear, and contraction within the Snake River Plain and the Northern Basin and Range Province, U.S.A. We estimate horizontal surface velocities using GPS data collected at 385 sites from 1994 to 2009 and present an updated velocity field within the Stable North American Reference Frame (SNARF). Our results show an ENE-oriented extensional strain rate of 5.9 {+-} 0.7 x 10{sup -9} yr{sup -1} in the Centennial Tectonic belt and an E-oriented extensional strain rate of 6.2 {+-} 0.3 x 10{sup -9} yr{sup -1} in the Intermountain Seismic belt combined with the northern Great Basin. These extensional strain rates contrast with the regional north-south contraction of -2.6 {+-} 1.1 x 10{sup -9} yr{sup -1} calculated in the Snake River Plain and Owyhee-Oregon Plateau over a 125 x 650 km region. Tests that include dike-opening reveal that rapid extension by dike intrusion in volcanic rift zones does not occur in the Snake River Plain at present. This slow internal deformation in the Snake River Plain is in contrast to the rapidly-extending adjacent Basin and Range provinces and implies shear along boundaries of the Snake River Plain. We estimate right-lateral shear with slip rates of 0.5-1.5 mm/yr along the northwestern boundary adjacent to the Centennial Tectonic belt and left-lateral oblique extension with slip rates of <0.5 to 1.7 mm/yr along the southeastern boundary adjacent to the Intermountain Seismic belt. The fastest lateral shearing occurs near the Yellowstone Plateau where strike-slip focal mechanisms and faults with observed strike-slip components of motion are documented. The regional GPS velocity gradients are best fit by nearby poles of rotation for the Centennial Tectonic belt, Idaho batholith, Snake River Plain, Owyhee-Oregon Plateau, and central Oregon, indicating that clockwise rotation is driven by extension to the

  8. Conditions of formation of the gas deposits in the Dneprovsk-Donets basin

    SciTech Connect

    Solov'ev, B.A.

    1986-06-01

    The major part of the gas resources of the Dneprovsk-Donets basin, concentrated in the southeast of the region, is associated with a complex of Late Carboniferous-Early Permian age, predominantly redbeds and extraordinarily poor in organic matter. In the northwest, these sediments are associated with oil deposits and in the central part of the basin with oil and gas deposits. The hydrocarbons in this complex undoubtedly entered from underlying petroleum source beds. An analysis of the observed zonation of hydrocarbons in the Upper Carboniferous-Lower Permian sequence leads to the conclusion that it was controlled to a decisive degree by the kind of original organic matter in the underlying sequences. These deposits offer an interesting history of interacting tectonic and hydrodynamic processes. 9 references.

  9. Geochemistry and isotope hydrology of representative aquifers in the Great Basin region of Nevada, Utah, and adjacent states

    USGS Publications Warehouse

    Thomas, J.M.; Welch, A.H.; Dettinger, M.D.

    1996-01-01

    This report briefly describes the general quality and chemical character of the ground water, discusses in detail the geochemical and hydrologic processes that produce the chemical and isotopic compositions of water in the two principal types of aquifers (basin fill and carbonate rock), delineates flow systems in carbonate-rock aquifers of southern Nevada, and discusses ground-water ages and flow velocities within the carbonate-rock systems.

  10. Water-level data for the Albuquerque Basin and adjacent areas, central New Mexico, period of record through September 30, 2015

    USGS Publications Warehouse

    Beman, Joseph E.; Bryant, Christina F.

    2016-10-27

    The Albuquerque Basin, located in central New Mexico, is about 100 miles long and 25–40 miles wide. The basin is hydrologically defined as the extent of consolidated and unconsolidated deposits of Tertiary and Quaternary age that encompasses the structural Rio Grande Rift between San Acacia to the south and Cochiti Lake to the north. Drinking-water supplies throughout the basin were obtained solely from groundwater resources until December 2008, when the Albuquerque Bernalillo County Water Utility Authority (ABCWUA) began treatment and distribution of surface water from the Rio Grande through the San Juan-Chama Drinking Water Project. A 20-percent population increase in the basin from 1990 to 2000 and a 22-percent population increase from 2000 to 2010 may have resulted in an increased demand for water in areas within the basin.An initial network of wells was established by the U.S. Geological Survey (USGS) in cooperation with the City of Albuquerque from April 1982 through September 1983 to monitor changes in groundwater levels throughout the Albuquerque Basin. In 1983, this network consisted of 6 wells with analog-to-digital recorders and 27 wells where water levels were measured monthly. The network currently (2015) consists of 124 wells and piezometers. (A piezometer is a specialized well open to a specific depth in the aquifer, often of small diameter and nested with other piezometers open to different depths.) The USGS, in cooperation with the ABCWUA, currently (2015) measures and reports water levels from the 124 wells and piezometers in the network; this report presents water-level data collected by USGS personnel at those 124 sites through water year 2015 (October 1, 2014, through September 30, 2015).

  11. Late miocene tidal deposits in the amazonian foreland basin.

    PubMed

    Räsänen, M E; Linna, A M; Santos, J C; Negri, F R

    1995-07-21

    Late Miocene tidal sediments of Acre, Brazilian Amazonia, were deposited in an embayment or interior seaway located in the sub-Andean zone. This late Tertiary embayment system may once have connected the Caribbean with the South Atlantic. The tidal coasts of the embayment-seaway have provided an avenue for the earliest waif (over water) dispersal phases of the great American biotic interchange in the late Miocene. The subsequent change from semimarine to terrestrial environments is of value in assessing the importance of earlier hypotheses on the evolution of the westem Amazonian landscape and gives insight into the formation of several observed biogeographic patterns, especially of aquatic biota.

  12. Late Miocene Tidal Deposits in the Amazonian Foreland Basin

    NASA Astrophysics Data System (ADS)

    Rasanen, Matti E.; Linna, Ari M.; Santos, Jose C. R.; Negri, Francisco R.

    1995-07-01

    Late Miocene tidal sediments of Acre, Brazilian Amazonia, were deposited in an embayment or interior seaway located in the sub-Andean zone. This late Tertiary embayment system may once have connected the Caribbean with the South Atlantic. The tidal coasts of the embayment-seaway have provided an avenue for the earliest waif (over water) dispersal phases of the great American biotic interchange in the late Miocene. The subsequent change from semimarine to terrestrial environments is of value in assessing the importance of earlier hypotheses on the evolution of the western Amazonian landscape and gives insight into the formation of several observed biogeographic patterns, especially of aquatic biota.

  13. Structure and tectonic evolution of the Tornquist Zone and adjacent sedimentary basins in Scania and the southern Baltic Sea area

    NASA Astrophysics Data System (ADS)

    Erlström, M.; Thomas, S. A.; Deeks, N.; Sivhed, U.

    1997-04-01

    Southernmost Sweden, Bornholm and the surrounding Baltic Sea region are located on a large-scale releasing bend in the dextral strike-slip system of the Tornquist Zone, with its resulting pull-apart basins. The well constrained geology of Scania and Bornholm has been combined with detailed on- and offshore borehole data and three proprietary marine seismic surveys. This in conjunction with supplementary BABEL deep seismic reflection findings allows a combined 3D interpretation of sediment/structure interactions. As a result, a regional interpretation has emerged which gives a new understanding of the interplay between structural movement on a complex strike-slip fault system (Tornquist Zone) and its intrazonal depressions (Vomb Trough and Colonus Shale Trough) as well as the sedimentation history of associated areas of sediment accumulation (Rønne and Arnager Grabens, Höllviken Halfgraben, Hanö Bay Basin and Skurup Platform). Detailed sequential litho- and seismo-stratigraphic descriptions have been possible by combination of the various data sets. This resulted in the clarification or recognition of previously unknown structural limits to sub-basins and highs in the study area. A 3D chronological (4D) model for the development of the region is proposed. This model takes into account the long-lived structural history combining elements of strike-slip, extension and inversion tectonics. The deep-seated faulting controlling these structures is integrated with the deep structure as revealed by the BABEL line in this area.

  14. Landscape change and megafan deposition in the Denver Basin during the PETM

    NASA Astrophysics Data System (ADS)

    Fricke, H. C.; Kochevar, B.; Clyde, W. C.; Snell, K. E.; Martin, K.; Miller, I.

    2011-12-01

    The Denver Basin is one of many structures that formed in western North America during the compressional Laramide Orogeny, and like other Laramide basins it is characterized by synorogenic alluvial and fluvial sedimentation that preserves a depositional record from the Late Cretaceous through the Eocene. Rocks in the Denver Basin have been grouped into two units separated by an unconformity of ~8 Ma: (1) the lower D1 sequence that spans the K/Pg and includes the early Paleocene, and (2) the overlying D2 sequence that is characterized by a prominent series of stacked paleosol/redbeds at its base, fluvial channel and overbank deposits lacking strong paleosol development, and an erosional unconformity at its top. Palynological and radiometric evidence suggests that the D2 is early Eocene in age. Historically, the D1 and D2 sequences have been interpreted to reflect two different pulses of synorogenic sedimentation associated with distinct episodes of uplift in the Front Range block during the Laramide Orogeny. It is possible, however, that D2 sedimentation did not occur as a result of renewed uplift, but instead reflects "megafan" deposition of large amounts of sediment as a result of climate change during the Paleocene-Eocene Thermal Maximum (PETM). In particular, a change to more seasonal precipitation, as indicated by the onset of paleosol/redbed formation, may have caused more frequent flooding events and thus increased sediment mobilization and deposition. To test this hypothesis, samples from two sediment cores drilled through D2 sediments were collected for carbon isotope analysis of bulk organic material in an effort to identify the carbon isotope excursion (CIE) associated with the PETM. At the base of the D2 sequence there is a ~5% decrease in carbon isotope ratios (δ13C) that begins in the redbeds and continues in the overlying fluvial overbank deposits. δ13C values then remain relatively constant at ~-28 % through the rest of the core. Both the magnitude

  15. Variations in fluvial deposition on an alluvial plain: an example from the Tongue River Member of the Fort Union Formation (Paleocene), southeastern Powder River Basin, Wyoming, U.S.A.

    USGS Publications Warehouse

    Johnson, E.A.; Pierce, F.W.

    1990-01-01

    The Tongue River Member of the Paleocene Fort Union Formation is an important coal-bearing sedimentary unit in the Powder River Basin of Wyoming and Montana. We studied the depositional environments of a portion of this member at three sites 20 km apart in the southeastern part of the basin. Six lithofacies are recognized that we assign to five depositional facies categorized as either channel or interchannel-wetlands environments. (1) Type A sandstone is cross stratified and occurs as lenticular bodies with concave-upward basal surfaces; these bodies are assigned to the channel facies interpreted to be the product of low-sinuosity streams. (2) Type B sandstone occurs in parallel-bedded units containing mudrock partings and fossil plant debris; these units constitute the levee facies. (3) Type C sandstone typically lacks internal structure and occurs as tabular bodies separating finer grained deposits; these bodies represent the crevasse-splay facies. (4) Gray mudrock is generally nonlaminated and contains ironstone concretions; these deposits constitute the floodplain facies. (5) Carbonaceous shale and coal are assigned to the swamp facies. We recognize two styles of stream deposition in our study area. Laterally continuous complexes of single and multistoried channel bodies occur at our middle study site and we interpret these to be the deposits of sandy braided stream systems. In the two adjacent study sites, single and multistoried channel bodies are isolated in a matrix of finer-grained interchannel sediment suggesting deposition by anastomosed streams. A depositional model for our study area contains northwest-trending braided stream systems. Avulsions of these systems created anastomosed streams that flowed into adjacent interchannel areas. We propose that during late Paleocene a broad alluvial plain existed on the southeastern flank of the Powder River Basin. The braided streams that crossed this surface were tributaries to a northward-flowing, basin

  16. Spatial patterns of cadmium and lead deposition on and adjacent to National Park Service lands in the vicinity of Red Dog Mine, Alaska

    SciTech Connect

    Hasselbach, L; Ver Hoef, J M.; Ford, Jesse; Neitlich, P; Crecelius, Eric A.; Berryman, Shanti D.; Wolk, B; Boehle, T

    2005-04-26

    Heavy metal escapement associated with ore trucks is known to affect the DeLong Mountain Regional Transportation System (DMTS) haul road corridor in Cape Krusenstern National Monument, northwest Alaska. Tissue concentrations in Hylocomium splendens moss (n = 226) were used to determine the extent and pattern of airborne heavy metal deposition on Monument lands. A stratified grid-based sample design was used with more intensive sampling near mining-related activities. Spatial predictions using geostatistical models were employed to produce maps of depositional patterns, and to estimate the geographic area affected above various thresholds. Spatial regression analyses indicated that heavy metal deposition decreased with the log of distance from the DMTS haul road and the DMTS port site. Analysis of subsurface soil demonstrated that observed patterns of heavy metal deposition reflected in moss tissue concentrations were not attributable to local subsurface lithology. Based on comparisons with regional background data from arctic Alaska, deposition of airborne heavy metals related to mining activities appears to affect the northern half of the Monument. The affected area extends northward (beyond Monument boundaries) through the Kisimilot/Iyikrok hills (north of the Wulik River), and possibly beyond. South of the DMTS haul road, airborne deposition appears to be constrained by the Tahinichok Mountains. Moss tissue concentrations were highest immediately adjacent to the DMTS haul road (Cd > 24 mg/kg dw; Pb > 900 mg/kg dw). The influence of the mine site was not studied.

  17. Megascopic lithologic studies of coals in the Powder River basin in Wyoming and in adjacent basins in Wyoming and North Dakota

    USGS Publications Warehouse

    Trippi, Michael H.; Stricker, Gary D.; Flores, Romeo M.; Stanton, Ronald W.; Chiehowsky, Lora A.; Moore, Timothy A.

    2010-01-01

    Between 1999 and 2007, the U.S. Geological Survey (USGS) investigated coalbed methane (CBM) resources in the Wyoming portion of the Powder River Basin. The study also included the CBM resources in the North Dakota portion of the Williston Basin of North Dakota and the Wyoming portion of the Green River Basin of Wyoming. This project involved the cooperation of the State Office, Reservoir Management Group (RMG) of the Bureau of Land Management (BLM) in Casper, Wyo., and 16 independent gas operators in the Powder River, Williston, and Green River Basins. The USGS and BLM entered into agreements with these CBM operators to supply samples for the USGS to analyze and provide the RMG with rapid, timely results of total gas desorbed, coal quality, and high-pressure methane adsorption isotherm data. This program resulted in the collection of 963 cored coal samples from 37 core holes. This report presents megascopic lithologic descriptive data collected from canister samples extracted from the 37 wells cored for this project.

  18. Tectonic control of Cretaceous gravity deposits and submarine Valleys in the subalpine basin, French western Alps

    SciTech Connect

    Philippe, J.; Beaudoin, B.; Fries, G.; Parize, O.

    1988-08-01

    The Late Jurassic-Early Cretaceous series of the French subalpine basin is characterized by alternating limestones and marls with numerous, thick gravity-flow deposits (carbonate debris flows and slumps, siliciclastic grain flows, turbidites). These gravity deposits originate from platforms and slopes and come through the basin via several parallel canyons and submarine valleys. Some carbonate (Berriasian) and siliciclastic (Aptian) deep-sea fans are built at the canyon mouth during intense activity of the canyons and reworking of the sediments. The tectonic control of the gravity deposits is demonstrated by the position and filling of the submarine valleys all along the Cretaceous. The submarine valleys correspond systematically to the lower part of extensional tilted blocks; the gravity deposits come along the main syn-sedimentary normal faults delimiting these tilted blocks. The gravity deposits go from one tilted block to another through some synsedimentary passes which are induced by slight folding, perhaps related to an early diapirism at some nodes of extensional faults. The canyon-like valleys are due to very strong erosion when a submarine valley cuts of the higher part of a tilted block. The gravity deposits are stacked atop each other and progressively fill the valleys. Thus the cutting and filling of the submarine valleys and canyons on occasions during the Early Cretaceous are explained by a permanent synsedimentary activity. These Jurassic and Cretaceous extensional structures are later reactivated by inversion during Tertiary compressional movements.

  19. Formation of the enigmatic Matoush uranium deposit in the Paleoprotozoic Otish Basin, Quebec, Canada

    NASA Astrophysics Data System (ADS)

    Alexandre, Paul; Kyser, Kurt; Layton-Matthews, Daniel; Beyer, Steve R.; Hiatt, Eric E.; Lafontaine, Jonathan

    2015-10-01

    The Matoush uranium deposit is situated in the Paleoproterozoic Otish Basin, northern Quebec, Canada, and is hosted by the Indicator Formation sandstones. Its sheet-like ore bodies are closely associated with the steeply dipping Matoush Fracture, which hosts mafic dykes and minor quartz-feldspar-tourmaline pegmatites. Regional diagenesis, involving oxidizing basinal fluids (δ2H ˜-15‰, δ18O ˜8‰), produced mostly illite and possibly leached U from accessory phases in the Indicator Formation sandstones. The bimodal Matoush dyke intruded the Indicator Formation along the Matoush Fracture, and the related metasomatism produced Cr-rich dravite and muscovite in both the dyke and the proximal sandstones. Uraninite formed when U6+ in the basinal brine was reduced to U4+ in contact with the mafic dyke and by Fe2+ in Cr-dravite and Cr-muscovite, and precipitated together with eskolaite and hematite. Because of its unique characteristics, the Matoush deposit cannot be easily classified within the generally accepted classification of uranium deposits. Two of its main characteristics (unusual reduction mechanism, structural control) do not correspond to the sandstone-hosted group of deposits (unconformity type, tabular, roll front), in spite of uranium being derived from the Otish Group sandstones.

  20. Lunar mare deposits associated with the Orientale impact basin: New insights into mineralogy, history, mode of emplacement, and relation to Orientale Basin evolution from Moon Mineralogy Mapper (M3) data from Chandrayaan-1

    USGS Publications Warehouse

    Whitten, J.; Head, J.W.; Staid, M.; Pieters, C.M.; Mustard, J.; Clark, R.; Nettles, J.; Klima, R.L.; Taylor, L.

    2011-01-01

    Moon Mineralogy Mapper (M3) image and spectral reflectance data are combined to analyze mare basalt units in and adjacent to the Orientale multiring impact basin. Models are assessed for the relationships between basin formation and mare basalt emplacement. Mare basalt emplacement on the western nearside limb began prior to the Orientale event as evidenced by the presence of cryptomaria. The earliest post-Orientale-event mare basalt emplacement occurred in the center of the basin (Mare Orientale) and postdated the formation of the Orientale Basin by about 60-100 Ma. Over the next several hundred million years, basalt patches were emplaced first along the base of the Outer Rook ring (Lacus Veris) and then along the base of the Cordillera ring (Lacus Autumni), with some overlap in ages. The latest basalt patches are as young as some of the youngest basalt deposits on the lunar nearside. M3 data show several previously undetected mare patches on the southwestern margins of the basin interior. Regardless, the previously documented increase in mare abundance from the southwest toward the northeast is still prominent. We attribute this to crustal and lithospheric trends moving from the farside to the nearside, with correspondingly shallower density and thermal barriers to basaltic magma ascent and eruption toward the nearside. The wide range of model ages for Orientale mare deposits (3.70-1.66 Ga) mirrors the range of nearside mare ages, indicating that the small amount of mare fill in Orientale is not due to early cessation of mare emplacement but rather to limited volumes of extrusion for each phase during the entire period of nearside mare basalt volcanism. This suggests that nearside and farside source regions may be similar but that other factors, such as thermal and crustal thickness barriers to magma ascent and eruption, may be determining the abundance of surface deposits on the limbs and farside. The sequence, timing, and elevation of mare basalt deposits

  1. Wet and dry nitrogen deposition in the central Sichuan Basin of China

    NASA Astrophysics Data System (ADS)

    Kuang, Fuhong; Liu, Xuejun; Zhu, Bo; Shen, Jianlin; Pan, Yuepeng; Su, Minmin; Goulding, Keith

    2016-10-01

    Reactive nitrogen (Nr) plays a key role in the atmospheric environment and its deposition has induced large negative impacts on ecosystem health and services. Five-year continuous in-situ monitoring of N deposition, including wet (total nitrogen (WTN), total dissolved nitrogen (WTDN), dissolved organic nitrogen (WDON), ammonium nitrogen (WAN) and nitrate nitrogen (WNN)) and dry (DNH3, DHNO3, DpNH4+, DpNO3- and DNO2) deposition, had been conducted since August 2008 to December 2013 (wet) and May 2011 to December 2013 (dry) in Yan-ting, China, a typical agricultural area in the central Sichuan Basin. Mean annual total N deposition from 2011 to 2013 was 30.8 kg N ha-1 yr-1, and speculated that of 2009 and 2010 was averaged 28.2 kg N ha-1 yr-1, respectively. Wet and dry N deposition accounted for 76.3% and 23.7% of annual N deposition, respectively. Reduced N (WAN, DNH3 and DpNH4+) was 1.7 times of oxidized N (WNN, DHNO3, DNO2 and DpNO3-) which accounted for 50.9% and 30.3% of TN, respectively. Maximum loadings of all N forms of wet deposition, gaseous NH3, HNO3 and particulate NH4+ in dry deposition occurred in summer and minimum loadings in winter. Whether monthly, seasonal or annual averaged, dissolved N accounted for more than 70% of the total. N deposition in the central Sichuan Basin increased during the sampling period, especially that of ammonium compounds, and has become a serious threat to local aquatic ecosystems, the surrounding forest and other natural or semi-natural ecosystems in the upper reaches of the Yangtze River.

  2. Assessment of macroinvertebrate communities in adjacent urban stream basins, Kansas City, Missouri, metropolitan area, 2007 through 2011

    USGS Publications Warehouse

    Christensen, Eric D.; Krempa, Heather M.

    2013-01-01

    Wastewater-treatment plant discharges during base flow, which elevated specific conductance and nutrient concentrations, combined sewer overflows, and nonpoint sources likely contributed to water-quality impairment and lower aquatic-life status at the Blue River Basin sites. Releases from upstream reservoirs to the Little Blue River likely decreased specific conductance, suspended-sediment, and dissolved constituent concentrations and may have benefitted water quality and aquatic life of main-stem sites. Chloride concentrations in base-flow samples, attributable to winter road salt application, had the highest correlation with the SUII (Spearman’s ρ equals 0.87), were negatively correlated with the SCI (Spearman’s ρ equals -0.53) and several pollution sensitive Ephemeroptera plus Plecoptera plus Trichoptera abundance and percent richness metrics, and were positively correlated with pollution tolerant Oligochaeta abundance and percent richness metrics. Study results show that the easily calculated SUII and the selected modeled multimetric indices are effective for comparing urban basins and for evaluation of water quality in the Kansas City metropolitan area.

  3. Fast Deposition of Small River Particles on the NE South China Sea Slope Basin Since the Last Glacial Maximum

    NASA Astrophysics Data System (ADS)

    Lin, S.; Cheng, W. Y.; Hsieh, I. C.

    2015-12-01

    Huge quantities of small rivers derived suspended particles are exporting to the ocean from oceanic islands at the present time. Depending on location and proportion of shelf/slope area, a major fraction of small river particles may by-pass the shelf region, transport and deposit on the deep ocean basin. Major mechanisms driving those huge quantities of small river derived particles to the ocean are quantity of precipitation from monsoon and those from short period of tropical cyclone. Although data demonstrate that deeper part of the South China Sea, SCS, is the major final burial location of the river derived particles from the island of Taiwan, it is not sure if this was the same during the glaciation when monsoon and climatic conditions were drastic different from the present time. The purpose of this study is to understand history of small river derived sediment export and deposition during climatic change. A long piston core with length of ~35 meter was taken on r/v Marion DuFresne on a slope basin offshore SW Taiwan. We have measured density, magnetic susceptibility with multi-sensor core logger, MSCL, and organic, inorganic carbon, C/N ratio, biogenic silica as well as grain sizes. Foraminifera (Orbulina universa, Globigerinoides sacculifer and Globigerinoides conglobatus) were picked and measured carbon 14 for age determination. Two different types of processes control sediment deposition in our study site, steady state and event driven sedimentation. Our results demonstrated that sedimentation rates were consistent during each major periods, the Holocene (present to 10k year) and the transition (10-20 k year) period, but, difference existed in between the two. Sedimentation rate was about twice faster during the transition period (20-10k year) than that at the Holocene (10-present time) at our study site. A number of spikes existed in our study site, probably a result of turbidite overflow from the adjacent canyon. Frequency and total thickness of event

  4. Mapping the hydraulic connection between a coalbed and adjacent aquifer: example of the coal-seam gas resource area, north Galilee Basin, Australia

    NASA Astrophysics Data System (ADS)

    Jiang, Zhenjiao; Mariethoz, Gregoire; Schrank, Christoph; Cox, Malcolm; Timms, Wendy

    2016-12-01

    Coal-seam gas production requires groundwater extraction from coal-bearing formations to reduce the hydraulic pressure and improve gas recovery. In layered sedimentary basins, the coalbeds are often separated from freshwater aquifers by low-permeability aquitards. However, hydraulic connection between the coalbed and aquifers is possible due to the heterogeneity in the aquitard such as the existence of conductive faults or sandy channel deposits. For coal-seam gas extraction operations, it is desirable to identify areas in a basin where the probability of hydraulic connection between the coalbed and aquifers is low in order to avoid unnecessary loss of groundwater from aquifers and gas production problems. A connection indicator, the groundwater age indictor (GAI), is proposed, to quantify the degree of hydraulic connection. The spatial distribution of GAI can indicate the optimum positions for gas/water extraction in the coalbed. Depressurizing the coalbed at locations with a low GAI would result in little or no interaction with the aquifer when compared to the other positions. The concept of GAI is validated on synthetic cases and is then applied to the north Galilee Basin, Australia, to assess the degree of hydraulic connection between the Aramac Coal Measure and the water-bearing formations in the Great Artesian Basin, which are separated by an aquitard, the Betts Creek Beds. It is found that the GAI is higher in the western part of the basin, indicating a higher risk to depressurization of the coalbed in this region due to the strong hydraulic connection between the coalbed and the overlying aquifer.

  5. Mapping of the air-sea CO2 flux in the Arctic Ocean and its adjacent seas: Basin-wide distribution and seasonal to interannual variability

    NASA Astrophysics Data System (ADS)

    Yasunaka, Sayaka; Murata, Akihiko; Watanabe, Eiji; Chierici, Melissa; Fransson, Agneta; van Heuven, Steven; Hoppema, Mario; Ishii, Masao; Johannessen, Truls; Kosugi, Naohiro; Lauvset, Siv K.; Mathis, Jeremy T.; Nishino, Shigeto; Omar, Abdirahman M.; Olsen, Are; Sasano, Daisuke; Takahashi, Taro; Wanninkhof, Rik

    2016-09-01

    We produced 204 monthly maps of the air-sea CO2 flux in the Arctic north of 60°N, including the Arctic Ocean and its adjacent seas, from January 1997 to December 2013 by using a self-organizing map technique. The partial pressure of CO2 (pCO2) in surface water data were obtained by shipboard underway measurements or calculated from alkalinity and total inorganic carbon of surface water samples. Subsequently, we investigated the basin-wide distribution and seasonal to interannual variability of the CO2 fluxes. The 17-year annual mean CO2 flux shows that all areas of the Arctic Ocean and its adjacent seas were net CO2 sinks. The estimated annual CO2 uptake by the Arctic Ocean was 180 TgC yr-1. The CO2 influx was strongest in winter in the Greenland/Norwegian Seas (>15 mmol m-2 day-1) and the Barents Sea (>12 mmol m-2 day-1) because of strong winds, and strongest in summer in the Chukchi Sea (∼10 mmol m-2 day-1) because of the sea-ice retreat. In recent years, the CO2 uptake has increased in the Greenland/Norwegian Sea and decreased in the southern Barents Sea, owing to increased and decreased air-sea pCO2 differences, respectively.

  6. The Tiberias Basin salt deposits and their effects on lake salinity

    NASA Astrophysics Data System (ADS)

    Inbar, Nimrod; Rosenthal, Eliahu; Möller, Peter; Yellin-Dror, Annat; Guttman, Josef; Siebert, Christian; Magri, Fabien

    2015-04-01

    Lake Tiberias is situated in one of the pull-apart basins comprising the Dead Sea transform. The Tiberias basin extends along the northern boundary of the Lower Jordan Rift Valley (LJRV) which is known for its massive salt deposits, mostly at its southern end, at the Dead Sea basin. Nevertheless, prior to the drilling of Zemah-1 wildcat, drilled close to the southern shores of Lake Tiberias, the Tiberias Basin was considered rather shallow and free of salt deposits (Starinsky, 1974). In 1983, Zemah-1 wildcat penetrated 2.8 km thick sequence of sedimentary and magmatic rocks of which 980m are salt deposits (Marcus et al., 1984). Recent studies, including the presented geophysical investigations, lay out the mechanisms of salt deposition in the Tiberias basin and estimate its abundance. Supported by seismic data, our interpreted cross-sections display relatively thick salt deposits distributed over the entire basin. Since early days of hydrological research in the area, saline springs are known to exist at Lake Tiberias' surroundings. Water temperatures in some of the springs indicate their origin to be at depths of 2-3 km (Simon and Mero, 1992). In the last decade, several studies suggested that the salinity of springs may be attributed, at least partially, to the Zemah-1 salt deposits. Chemical justification was attributed to post-halite minerals which were thought to be present among those deposits. This hypothesis was never verified. Moreover, Möller et al. (2011) presented a calculation contradicting this theory. In addition to the geophysical investigations, numerical models of thermally driven flow, examine the possible fluid dynamics developing near salt deposits below the lake and their interactions with springs along the lakeshore (Magri et al., 2015). It is shown that leached halite is too heavy to reach the surface. However, salt diffusing from shallow salt crest may locally reach the western side of the lakeshore. References Magri, F., N. Inbar

  7. The history of mare volcanism in the Orientale Basin: Mare deposit ages, compositions and morphologies

    NASA Technical Reports Server (NTRS)

    Kadel, S. D.; Greeley, R.; Neukum, G.; Wagner, R.

    1993-01-01

    The eruptive history of mare basalts in the Orientale Basin has been studied, using Lunar Orbiter 4 high-resolution photographs, Zond 8 photographs, and recently acquired Galileo EM-1 multispectral images. This work represents a refined set of compositional data incorporating the use of a linear mixing model for mare compositions, crater count data, and a comprehensive morphologic analysis of Orientale Basin mare deposits. Evidence for multiple eruptive episodes has been found, with compositions ranging from medium- to high-Ti basalt (less than 4 to greater than 6 wt. percent TiO2). Eruptive styles included flood, rille-forming, and shield-forming eruptions. Impact crater densities of mare units in the Orientale Basin enable determination of the ages of these deposits, using the method of Neukum et al. Earliest eruptions of mare basalt in the basin occurred at greater than or equal to 3.80 Ga and the latest eruptions occurred at about 2.3-2.5 Ga. Hence, mare volcanism occurred over a period of nearly 1.5 Ga.

  8. Depositional environments and regional sedimentological control of Caseyville Formation, southern Illinois basin

    SciTech Connect

    Nelson, W.J.; Pius Weibel, C. )

    1989-08-01

    During the Morrowan Epoch (earliest Pennsylvanian), the Eastern Interior basins of the US were characterized by a fluviatile system draining generally southwestward from central Pennsylvanian to the Arkoma basin of northern Arkansas. In the southern Illinois basin, the system deposited the Casevylle Formation, consisting of two prominent cliff-forming quartzose sandstones with common quartz gravel, separated and succeeded by finer-grained, clastic intervals. Outcrop mapping in southernmost Illinois indicates that these cliff formers, the Battery Rock and Pounds Sandstone members, are laterally widespread and generally continuous, but variable in thickness. The underlying Wayside Sandstone Member, the intervening Drury Shale Member, and strata immediately succeeding the Caseyville consist of variable sequences of shales, siltstones, thin-bedded sandstones, and local ledge-forming sandstones. Rare lenticular coals are scattered through the Caseyville. The authors interpret the sandstone members to be dominantly of fluviatile-deltaic origin and the intervening, finger-grained intervals to be of deltaic and, at least in part, marginal-marine origin. Marine strata within the Drury Shale Member and the strata immediately overlying the Caseyville Formation contain scattered body fossils and trace fossils suggesting marine deposition. The Wayside/Battery Rock and Drury/Pounds cycles are tentatively correlated with similar cycles in the Appalachian and Arkoma basins. This correlation suggests regional sedimentological control.

  9. Evidence for deep-water evaporite deposition in the Miocene Kareem Formation, Gemsa basin, eastern Egypt

    SciTech Connect

    May, J.A.; Stonecipher, S.A.; Steinmetz, J.C. ); Dyess, J.N. )

    1991-03-01

    The correct interpretation of intercalated Miocene siliciclastics and evaporites of Gemsa basin is crucial for understanding early rift tectonics of the Gulf of Suez, pinpointing the timing of isolation of the Gulf from the Mediterranean, and developing exploration plays. Evaporites of the Kareem Formation comprise celestites and massive, 'chicken-wire,' and laminated anhydrites. Although previously interpreted as sabkha deposits; sedimentologic, petrographic, and paleontologic analyses indicate these evaporites more likely formed in a submarine setting. Marls that encase the evaporites contain a diverse and abundant assemblage of nannoplankton, planktonic foraminifera, diatoms, pteropods, and fish scales indicative of basinal deposition. Associated turbidites also denote deep-water sedimentation. The paucity of benthic diatoms and foraminifera, plus the presence of unburrowed shales, phosphate nodules, early ferroan carbonate cements, and authigenic pyrite, suggest periodic anoxic, or at least disaerobic, bottom waters. These sequences probably represent partial isolation of the Gulf of Suez by middle Miocene, producing periodic basin restriction and evaporative drawdown. Episodes of increasing salinity likely caused the progressive decreases in foram abundance and diversity in marls beneath the anhydrites, culminating in subaqueous evaporite formation. Diverse, indigenous nannoplankton assemblages from shale seams within the anhydrites suggest Gemsa basin was stratified; shallow open-marine conditions coexisted with anhydrite crystallization from deeper hypersaline waters.

  10. Ground water in the alluvial deposits of Cottonwood Creek Basin, Oklahoma

    USGS Publications Warehouse

    Stacy, B.L.

    1960-01-01

    Cottonwood Creek basin is a 377 square mile area in central Oklahoma. The rim of the basin has altitudes as high as 1,300 feet, and the mouth is at an altitude of 910. Deposits of Quaternary age consist of alluvium along the stream courses and high terrace deposits along the southern rim of the basin. The alluvium contains a high percentage of clay and silt, ranges in thickness from a few inches to 40 feet, and underlies about 36 square miles of the basin. Sandstone, siltstone, and shale of Permian age, which form the bedrock, consist of the Garber sandstone along the eastern edge, the Hennessey shale through the central part, and Flowerpot shale along the western edge. Replenishment of water in the alluvium is from precipitation, lateral seepage and runoff from adjoining areas, and infiltration from the stream channels during high flows. The major use of ground water in the alluvium is transpiration by cottonwood and willow trees. Virtually no water is withdrawn from the alluvium by wells. (available as photostat copy only)

  11. Characterization of surface-water resources in the Great Basin National Park area and their susceptibility to ground-water withdrawals in adjacent valleys, White Pine County, Nevada

    USGS Publications Warehouse

    Elliott, Peggy E.; Beck, David A.; Prudic, David E.

    2006-01-01

    Eight drainage basins and one spring within the Great Basin National Park area were monitored continually from October 2002 to September 2004 to quantify stream discharge and assess the natural variability in flow. Mean annual discharge for the stream drainages ranged from 0 cubic feet per second at Decathon Canyon to 9.08 cubic feet per second at Baker Creek. Seasonal variability in streamflow generally was uniform throughout the network. Minimum and maximum mean monthly discharges occurred in February and June, respectively, at all but one of the perennial streamflow sites. Synoptic-discharge, specific-conductance, and water- and air-temperature measurements were collected during the spring, summer, and autumn of 2003 along selected reaches of Strawberry, Shingle, Lehman, Baker, and Snake Creeks, and Big Wash to determine areas where surface-water resources would be susceptible to ground-water withdrawals in adjacent valleys. Comparison of streamflow and water-property data to the geology along each stream indicated areas where surface-water resources likely or potentially would be susceptible to ground-water withdrawals. These areas consist of reaches where streams (1) are in contact with permeable rocks or sediments, or (2) receive water from either spring discharge or ground-water inflow.

  12. More than one way to stretch: A tectonic model for extension along the plume track of the Yellowstone hotspot and adjacent Basin and Range Province

    USGS Publications Warehouse

    Parsons, T.; Thompson, G.A.; Smith, R.P.

    1998-01-01

    The eastern Snake River Plain of southern Idaho poses a paradoxical problem because it is nearly aseismic and unfaulted although it appears to be actively extending in a SW-NE direction continuously with the adjacent block-faulted Basin and Range Province. The plain represents the 100-km-wide track of the Yellowstone hotspot during the last ???16-17 m.y., and its crust has been heavily intruded by mafic magma, some of which has erupted to the surface as extensive basalt flows. Outside the plain's distinct topographic boundaries is a transition zone 30-100 km wide that has variable expression of normal faulting and magmatic activity as compared with the surrounding Basin and Range Province. Many models for the evolution of the Snake River Plain have as an integral component the suggestion that the crust of the plain became strong enough through basaltic intrusion to resist extensional deformation. However, both the boundaries of the plain and its transition zone lack any evidence of zones of strike slip or other accommodation that would allow the plain to remain intact while the Basin and Range Province extended around it; instead, the plain is coupled to its surroundings and extending with them. We estimate strain rates for the northern Basin and Range Province from various lines of evidence and show that these strains would far exceed the elastic limit of any rocks coupled to the Basin and Range; thus, if the plain is extending along with its surroundings, as the geologic evidence indicates, it must be doing so by a nearly aseismic process. Evidence of the process is provided by volcanic rift zones, indicators of subsurface dikes, which trend across the plain perpendicular to its axis. We suggest that variable magmatic strain accommodation, by emplacement and inflation of dikes perpendicular to the least principal stress in the elastic crust, allows the crust of the plain to extend nearly aseismically. Dike injection releases accumulated elastic strain but

  13. From source to sink in central Gondwana: Exhumation of the Precambrian basement rocks of Tanzania and sediment accumulation in the adjacent Congo basin

    NASA Astrophysics Data System (ADS)

    Kasanzu, Charles Happe; Linol, Bastien; Wit, Maarten J.; Brown, Roderick; Persano, Cristina; Stuart, Finlay M.

    2016-09-01

    Apatite fission track (AFT) and (U-Th)/He (AHe) thermochronometry data are reported and used to unravel the exhumation history of crystalline basement rocks from the elevated (>1000 m above sea level) but low-relief Tanzanian Craton. Coeval episodes of sedimentation documented within adjacent Paleozoic to Mesozoic basins of southern Tanzania and the Congo basin of the Democratic Republic of Congo indicate that most of the cooling in the basement rocks in Tanzania was linked to erosion. Basement samples were from an exploration borehole located within the craton and up to 2200 m below surface. Surface samples were also analyzed. AFT dates range between 317 ± 33 Ma and 188 ± 44 Ma. Alpha (Ft)-corrected AHe dates are between 433 ± 24 Ma and 154 ± 20 Ma. Modeling of the data reveals two important periods of cooling within the craton: one during the Carboniferous-Triassic (340-220 Ma) and a later, less well constrained episode, during the late Cretaceous. The later exhumation is well detected proximal to the East African Rift (70 Ma). Thermal histories combined with the estimated geothermal gradient of 9°C/km constrained by the AFT and AHe data from the craton and a mean surface temperature of 20°C indicate removal of up to 9 ± 2 km of overburden since the end of Paleozoic. The correlation of erosion of the craton and sedimentation and subsidence within the Congo basin in the Paleozoic may indicate regional flexural geodynamics of the lithosphere due to lithosphere buckling induced by far-field compressional tectonic processes and thereafter through deep mantle upwelling and epeirogeny tectonic processes.

  14. Subsurface geology and porosity distribution, Madison Limestone and underlying formations, Powder River basin, northeastern Wyoming and southeastern Montana and adjacent areas

    USGS Publications Warehouse

    Peterson, James A.

    1978-01-01

    To evaluate the Madison Limestone and associated rocks as potential sources for water supplies in the Powder River Basin and adjacent areas, an understanding of the geologic framework of these units, their lithologic facies patterns, the distribution of porosity zones, and the relation between porosity development and stratigraphic facies is necessary. Regionally the Madison is mainly a fossiliferous limestone. However, in broad areas of the eastern Rocky Mountains and western Great Plains, dolomite is a dominant constituent and in places the Madison is almost entirely dolomite. Within these areas maximum porosity development is found and it seems to be related to the coarser crystalline dolomite facies. The porosity development is associated with tabular and fairly continuous crystalline dolomite beds separated by non-porous limestones. The maximum porosity development in the Bighorn Dolomite, as in the Madison, is directly associated with the occurrence of a more coarsely crystalline sucrosic dolomite facies. Well data indicate, however, that where the Bighorn is present in the deeper parts of the Powder River Basin, it may be dominated by a finer crystalline dolomite facies of low porosity. The 'Winnipeg Sandstone' is a clean, generally well-sorted, medium-grained sandstone. It shows good porosity development in parts of the northern Powder River Basin and northwestern South Dakota. Because the sandstone is silica-cemented and quartzitic in areas of deep burial, good porosity is expected only where it is no deeper than a few thousand feet. The Flathead Sandstone is a predominantly quartzose, slightly feldspathic sandstone, commonly cemented with iron oxide. Like the 'Winnipeg Sandstone,' it too is silica-cemented and quartzitic in many places so that its porosity is poor in areas of deep burial. Illustrations in this report show the thickness, percent dolomite, and porosity-feet for the Bighorn Dolomite and the Madison Limestone and its subdivisions. The

  15. Geochemistry evidence for depositional settings and provenance of Jurassic argillaceous rocks of Jiyuan Basin, North China

    NASA Astrophysics Data System (ADS)

    Meng, Yao; Zheng, Deshun; Li, Minglong

    2017-02-01

    This paper aims to discuss the depositional settings and provenances for the Jurassic in Jiyuan basin, North China, based on the rare earth element (REE) and trace element features of 16 Jurassic argillaceous rock samples from the Anyao, Yangshuzhuang and Ma'ao Formations, respectively. Generally, geochemical analysis results show that chondrite-normalised REE distribution patterns of all the three formations are characterised by light-REE (LREE) enrichment, moderately negative Eu anomalies, slightly negative Ce anomalies, and strong fractionation between LREE and heavy-REE (HREE). Trace element proxies V/(V + Ni), Ce anom index, Ce/La, Sr/Ba, and Sr/Cu indicate a weak oxidation-reduction environment, progressively decreasing reducibility and water depth from the bottom up during Jurassic in Jiyuan basin. Palaeoclimate varied from humid in the Early Jurassic to arid in the Middle Jurassic, corresponding with the variations of palaeoredox and palaeosalinity. The provenances of Jurassic rocks in Jiyuan basin are mainly from felsic sources related to active continental margin and continental island arc. The Early-Middle Jurassic (Anyao and Yangshuzhuang Formations) provenances are mainly derived from North Qinling and partially from the eroded recycled felsic sedimentary covers of Taihang Mountain. In the late stage of Middle Jurassic (Ma'ao Formation), Taihang Mountain has been the primary source to Jiyuan basin. We conclude that the Jurassic rocks of Jiyuan basin reveal the progressive uplift and denudation processes of the Taihang Mountain.

  16. Performance of soil particle-size distribution models for describing deposited soils adjacent to constructed dams in the China Loess Plateau

    NASA Astrophysics Data System (ADS)

    Zhao, Pei; Shao, Ming-an; Horton, Robert

    2011-02-01

    Soil particle-size distributions (PSD) have been used to estimate soil hydraulic properties. Various parametric PSD models have been proposed to describe the soil PSD from sparse experimental data. It is important to determine which PSD model best represents specific soils. Fourteen PSD models were examined in order to determine the best model for representing the deposited soils adjacent to dams in the China Loess Plateau; these were: Skaggs (S-1, S-2, and S-3), fractal (FR), Jaky (J), Lima and Silva (LS), Morgan (M), Gompertz (G), logarithm (L), exponential (E), log-exponential (LE), Weibull (W), van Genuchten type (VG) as well as Fredlund (F) models. Four-hundred and eighty samples were obtained from soils deposited in the Liudaogou catchment. The coefficient of determination (R 2), the Akaike's information criterion (AIC), and the modified AIC (mAIC) were used. Based upon R 2 and AIC, the three- and four-parameter models were both good at describing the PSDs of deposited soils, and the LE, FR, and E models were the poorest. However, the mAIC in conjunction with R 2 and AIC results indicated that the W model was optimum for describing PSD of the deposited soils for emphasizing the effect of parameter number. This analysis was also helpful for finding out which model is the best one. Our results are applicable to the China Loess Plateau.

  17. Depositional facies and Hohokam settlement patterns of Holocene alluvial fans, N. Tucson Basin, Arizona

    SciTech Connect

    Field, J.J.

    1985-01-01

    The distribution of depositional facies on eight Holocene alluvial fans of varying dimensions is used to evaluate prehistoric Hohokam agricultural settlement patterns. Two facies are recognized: channel gravelly sand facies and overbank silty sand facies. No debris flow deposits occur. The channel facies is characterized by relatively well sorted stratified sands and gravels with common heavy mineral laminations. Overbank facies deposits are massive and very poorly sorted due to heavy bioturbation. Lithostratigraphic profiles from backhoe trenches and sediment size analysis document headward migration of depositional facies which results in fining upward sequences. Each sequence is a channel fan lobe with an underlying coarse grained channel sand which fines to overbank silty sands. Lateral and vertical variations in facies distributions show that depositional processes are affected by drainage basin area (fan size) and distance from fan head. Gravelly channel sands dominate at the headward portions of the fan and are more pervasive on large fans; overbank silty sands are ubiquitous at fan toes and approach closer to the fan head of smaller alluvial fans. When depositional facies are considered as records of water flow over an alluvial surface, the farming potential of each fan can be analyzed. Depositional models of alluvial fan sedimentation provide the basis for understanding Hohokam settlement patterns on active alluvial surfaces.

  18. 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

  19. Lithospheric flexure and sedimentary basin evolution: depositional cycles in the steer's head model

    NASA Astrophysics Data System (ADS)

    Moore, James; Watts, Tony

    2016-04-01

    Backstripping studies of biostratigraphic data from deep wells show that sediment loading is one of the main factors controlling the subsidence and uplift history of sedimentary basins. Previous studies based on single layer models of elastic and viscoelastic plates overlying an inviscid fluid have shown that sediment loading, together with a tectonic subsidence that decreases exponentially with time, can explain the large-scale 'architecture' of rift-type basins and, in some cases, details of their internal stratigraphy such as onlap and offlap patterns. One problem with these so-called 'steer's head' models is that they were based on a simple rheological model in which the long-term strength of the lithosphere increased with thermal age. Recent oceanic flexure studies, however, reveal that the long-term strength of the lithosphere depends not only on thermal age, but also load age. We have used the thermal structure based on plate cooling models, together with recent experimentally-derived flow laws, to compute the viscosity structure of the lithosphere and a new analytical model to compute the flexure of a multilayer viscoelastic plate by a trapezoid-shaped sediment load at different times since basin initiation. The combination of basin subsidence and viscoelastic flexural response results in the fluctuation of the depositional surface with time. If we define the nondimensional number Dw= τm/τt, where τm is the Maxwell time constant and τt is the thermal time constant, we find that for Dw<<1 the flexure approximates that of an elastic plate and is dominated by "onlapping" stratigraphy which evolves through the sedimentary facies with a progressive deepening of the depositional surface. For Dw>>1 the flexure approximates that of a viscoelastic plate and is dominated by "offlapping" stratigraphy, with the basin edges evolving through shallow marine facies; though erosion late in the basin formation prevents much of this from being recorded in the stratigraphy

  20. North Atlantic Ocean deep-water processes and depositional environments: A study of the Cenozoic Norway Basin

    NASA Astrophysics Data System (ADS)

    Oline Hjelstuen, Berit; Andreassen, Elin V.

    2015-04-01

    Despite the enormous areas deep-water basins occupy in modern oceans, our knowledge about them remains poor. At depths of greater than 2000 m, the Cenozoic Norway Basin in the northernmost part of the Atlantic Ocean, is one such basin. Interpretation of 2D multichannel seismic data suggests a three-stage evolution for the Norway Basin. (1) Eocene-Pliocene. This time period is characterised by deposition of ooze-rich sediments in a widening and deepening basin. (2) Early-Middle Pleistocene. A significant shift in sedimentary processes and depositional environments took place in the Early Pleistocene. Mass failures initiated on the Norwegian continental slope, and three Early and Middle Pleistocene slide debrites, with maximum thicknesses of 600 m and sediment volumes of up to 25000 km3, were deposited. With ages estimated at c. 2.7-1.7 Ma, 1.7-1.1 Ma and 0.5 Ma, these slide deposits are among the largest identified worldwide, and among the oldest mapped along the entire NE Atlantic continental margin. (3) Late Pleistocene-Present. Since c. 0.5 Ma the Norway Basin has been effected by glacigenic debris flows, the Storegga Slide and hemipelagic-glacimarine sedimentation. These sedimentary processes were active during a time of repeated shelf-edge ice advances along the NE Atlantic continental margin. This study shows that deep-water basins represent dynamic depositional environments reflecting regional tectonic and climatic changes trough time.

  1. Landslide deposit boundaries for the Little North Santiam River Basin, Oregon

    USGS Publications Warehouse

    Sobieszczyk, Steven

    2010-01-01

    This layer is an inventory of existing landslides deposits in the Little North Santiam River Basin, Oregon (2009). Each landslide deposit shown on this map has been classified according to a number of specific characteristics identified at the time recorded in the GIS database. The classification scheme was developed by the Oregon Department of Geology and Mineral Industries (Burns and Madin, 2009). Several significant landslide characteristics recorded in the database are portrayed with symbology on this map. The specific characteristics shown for each landslide are the activity of landsliding, landslide features, deep or shallow failure, type of landslide movement, and confidence of landslide interpretation. These landslide characteristics are determined primarily on the basis of geomorphic features, or landforms, observed for each landslide. This work was completed as part of the Master's thesis "Turbidity Monitoring and LiDAR Imagery Indicate Landslides are Primary Source of Suspended-Sediment Load in the Little North Santiam River Basin, Oregon, Winter 2009-2010" by Steven Sobieszczyk, Portland State University and U.S. Geological Survey.Data layers in this geodatabase include: landslide deposit boundaries (Deposits); field-verfied location imagery (Photos); head scarp or scarp flanks (Scarp_Flanks); and secondary scarp features (Scarps).The geodatabase template was developed by the Oregon Department of Geology and Mineral Industries (Burns and Madin, 2009).

  2. Stratigraphic framework and estuarine depositional environments of the Miocene Bear Lake Formation, Bristol Bay Basin, Alaska: Onshore equivalents to potential reservoir strata in a frontier gas-rich basin

    USGS Publications Warehouse

    Finzel, E.S.; Ridgway, K.D.; Reifenstuhl, R.R.; Blodgett, R.B.; White, J.M.; Decker, P.L.

    2009-01-01

    The Miocene Bear Lake Formation is exposed along the coast and mountains of the central Alaska Peninsula and extends offshore as part of the Bristol Bay Basin. The Bear Lake Formation is up to 2360 m (7743 ft) thick in an offshore well and is considered to have the highest reservoir potential in this gasrich frontier basin. Our new macrofossil and palynological data, collected in the context of measured stratigraphic sections, allow us to construct the first chronostratigraphic framework for this formation. Biostratigraphic age assignments for the numerous, commonly isolated, onshore exposures of the Bear Lake Formation show that deposition initiated sometime before the middle Miocene (15 Ma) and extended to possibly the earliest Pliocene. The bulk of the Bear Lake Formation, however, was deposited during the middle and late Miocene based on our new findings. We interpret the Bear Lake Formation as the product of a regional transgressive estuarine depositional system based on lithofacies analysis. The lower part of the formation is characterized by trough cross-stratified sandstone interbedded with coal and pedogenic mudstone deposited in fluvial and swamp environments of the uppermost parts of the estuarine system. The lower-middle part of the formation is dominated by nonbioturbated, wavy- and flaser-bedded sandstone and siltstone that were deposited in supratidal flat environments. The uppermiddle part of the Bear Lake Formation is characterized by inclined heterolithic strata and coquinoid mussel beds that represent tidal channel environments in the middle and lower tracts of the estuarine system. The uppermost part of the formation consists of tabular, bioturbated sandstone with diverse marine invertebrate macrofossil faunas. We interpret this part of the section as representing the subtidal tract of the lower estuarine system and possibly the adjacent shallow inner shelf. A comparison of our depositional framework for the Bear Lake Formation with core and

  3. Tectonic and depositional model of the North Louisiana-South Arkansas basin

    SciTech Connect

    Sullivan, N.M. ); Lowrie, A. ); Krotzer, C.J.; Carter, J.; Lerche, I.; Petersen, K. )

    1993-09-01

    A tectonic and depositional model is presented for the North Louisiana-South Arkansas (NL-SA) basin. This area is defined as extending from the updip sedimentary outcrop limit of the Mississippi Embayment, to the Sabine uplift and its possible eastward extension to the Wiggens arch in the south, and lying between the Sabine and Monroe uplifts. Included in this designation is the North Louisiana Salt basin. Geohistory modeling of basin subsidence with time has been correlated to sediment deposition, as well as to regional climatic and oceanographic information. In each instance, quantification and/or ranges of the natural processes are provided. The objective is to develop a dynamic model framework accurate enough to underpin individual prospects with regional understanding. The tectonic chronology begins with (1) subduction in the lower Paleozoic, followed by (2) incipient and interrupted rifting that is possibly part of mantle plume rising in the upper Paleozoic. A second episode of magmatic intrusion associated with Upper Jurassic sea-floor spreading south of the Sabine uplift. Regional subsidence occurred from the edge of the Mississippi Embayment through the North Louisiana Salt basin, including the proto-Sabine uplift. Lower Cretaceous cessation of the central Gulf of Mexico spreading was accompanied by initiation of tectonic subsidence and the beginning of the South Louisiana Salt basin. A continued regional downdip existed from the edge of the Mississippi Embayment through the proto-Sabine uplift region. Middle Cretaceous subsidence rate in the NL-SA area, also impacted the evolution of sedimentary fill and associated structural evolution.

  4. Gas Hydrate Deposits in the Cauvery-Mannar Offshore Basin, India

    NASA Astrophysics Data System (ADS)

    Dewangan, P.

    2015-12-01

    The analysis of geophysical and coring data from Mahanadi and Krishna-Godavari offshore basins, eastern continental margin of India, has established the presence of gas hydrate deposits; however, other promising petroliferous basins are relatively unexplored for gas hydrates. A collaborative program between GSI/MoM and CSIR-NIO was formulated to explore the Cauvery-Mannar offshore basin for gas hydrate deposits (Fig. 1a). High quality multi-channel reflection seismics (MCS) data were acquired with 3,000 cu. in airgun source array and 3 km long hydrophone streamer (240 channels) onboard R/V Samudra Ratnakar for gas hydrate studies. Other geophysical data such as gravity, magnetic and multibeam data were also acquired along with seismic data.After routine processing of seismic data, the bottom simulating reflectors (BSRs) are observed in the central and north-eastern part of the survey area. The BSRs are identified based on its characteristic features such as mimicking the seafloor, opposite polarity with respect to the seafloor and crosscutting the existing geological layers (Fig. 1b). At several locations, seismic signatures associated with free gas such as drop in interval velocity, pull-down structures, amplitude variation with offset (AVO) and attenuation are observed below the BSRs which confirm the presence of free gas in the study area. Acoustic chimneys are observed at some locations indicating vertical migration of the free gas. The observed seismic signatures established the presence of gas hydrates/free gas deposits in Cauvery-Mannar basin. Interestingly, BSRs appear to be distributed along the flanks of submarine canyon indicating the influence of geomorphology on the formation and distribution of gas hydrates.

  5. Depositional history of Lower Triassic Dinwoody Formation, Bighorn basin, Wyoming and Montana

    SciTech Connect

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

    1986-08-01

    The Lower Triassic Dinwoody Formation in the Bighorn basin of Wyoming and Montana records the northeasternmost extent of the widespread and rapid Griesbachian transgression onto the Wyoming shelf. Depositional patterns document a progressive change from sparsely fossiliferous, inner-shelf marine conditions in the southwest and west to restricted, marginal-marine environments to the north and east. Characteristic lithologies include greenish-gray calcareous or dolomitic mudstone and siltstone, very thin to thick beds of gypsum, and thin-bedded, commonly laminated dolomite. A formation thickness of approximately 20 m persists throughout most of the basin but diminishes abruptly near the northern and eastern limits of deposition. The Dinwoody is disconformable on the Ervay Member of the Permian Park City Formation except in the northeasternmost part of the basin, where it locally overlies the Pennsylvanian Tensleep Sandstone. Considering the significant time interval involved, physical evidence at the Permian-Triassic boundary is generally limited to an abrupt lithologic change from light-colored shallow marine or intertidal Permian dolomite to greenish-gray Dinwoody siltstone. The Dinwoody grades vertically as well as laterally to the east and north into red beds of the Lower Triassic Red Peak Formation of the Chugwater Group. The Early Triassic depositional environment in the present-day Bighorn basin was hostile. A sparse molluscan fauna was observed at only one of the 20 sections studied, and no conodonts were recovered from Dinwoody carbonates. Significant amounts of gypsum within the Dinwoody suggest periodic high evaporation from hypersaline waters on a low-energy shallow shelf during intervals of reduced terrigenous sediment supply from the north and east. However, sufficient organic material was present to create reducing conditions, as evidenced by greenish rock color and abundant pyrite.

  6. Metallogeny of the Great Basin: crustal evolution, fluid flow, and ore deposits

    USGS Publications Warehouse

    Hofstra, Albert H.; Wallace, Alan R.

    2006-01-01

    The Great Basin physiographic province in the Western United States contains a diverse assortment of world-class ore deposits. It currently (2006) is the world's second leading producer of gold, contains large silver and base metal (Cu, Zn, Pb, Mo, W) deposits, a variety of other important metallic (Fe, Ni, Be, REE's, Hg, PGE) and industrial mineral (diatomite, barite, perlite, kaolinite, gallium) resources, as well as petroleum and geothermal energy resources. Ore deposits are most numerous and largest in size in linear mineral belts with complex geology. U.S. Geological Survey (USGS) scientists are in the final year of a research project initiated in the fall of 2001 to increase understanding of relations between crustal evolution, fluid flow, and ore deposits in the Great Basin. Because of its substantial past and current mineral production, this region has been the focus of numerous investigations over the past century and is the site of ongoing research by industry, academia, and state agencies. A variety of geoinformatic tools was used to organize, reinterpret, and display, in space and time, the large amounts of geologic, geophysical, geochemical, and hydrologic information deemed pertinent to this problem. This information, in combination with concentrated research on (1) critical aspects of the geologic history, (2) an area in northern Nevada that encompasses the major mineral belts, and (3) important mining districts and deposits, is producing new insights about the interplay between key tectonic events, hydrothermal fluid flow, and ore genesis in mineral belts. The results suggest that the Archean to Holocene history of the Great Basin was punctuated by several tectonic events that caused fluids of different origins (sea water, basinal brine, meteoric water, metamorphic water, magmatic water) to move through the crust. Basement faults reactivated during these events localized deformation, sedimentation, magmatism, and hydrothermal fluid flow in overlying

  7. Precambrian to Jurassic rocks of Arabian Gulf and adjacent areas: their facies, depositional setting, and hydrocarbon habitat

    SciTech Connect

    Alsharhan, A.S.; Kendal, C.G.S.C.

    1986-08-01

    The first sediments to onlap the metamorphosed Precambrian Arabian shield were Infracambrian (Proterozoic) to Middle Cambrian carbonates, clastics, and evaporites. The oldest Arabian reservoir rocks occur in the Precambrian to lower Paleozoic Era Salt of the Huqf Group, which forms the Birba field of Oman. The Middle Cambrian sequence was followed by Late Cambrian through Early Permian marine sandstones and continental to littoral siltstones and variegated shales. The first commercial oil discovered in the Arabian Gulf region occurs in fluvial sands of the Ordovician to Permian Haima and Haushi Groups of the Marmul field in south Oman. These strata are also productive in other fields and are sealed by unconformable contact with the Al Khlata Formation or beneath shale of the Albian Nahr Umr Formation. The deeply buried kerogen sediments of the Huqf Group to the southeast are believed to be the source rocks for these fields of south Oman. The Late Permian to Triassic deposits of the Arabian Peninsula are mainly widespread carbonates and evaporites that were deposited during a period of relative tectonic stability. Their deposition on an epeiric shelf was punctuated by a series of transgressions and regressions. Significant gas reserves have been proven in deep wells in the Arabian Gulf. These wells penetrate large deep structures in the Permian Khuff shelf carbonates. These carbonates have developed secondary porosity and lie beneath interbedded shale and dolomites of the Sudair or Suwei Formation. The source of gas in the Khuff is unknown but could lie in more deeply buried formations. The large deep structures of the Khuff are considered to be among the most attractive for gas potential in the region today. 14 figures, 2 tables.

  8. Tectonic controls on deposition and preservation of Pennsylvanian Tensleep Formation, Bighorn basin, Wyoming

    SciTech Connect

    Kelly Anne, O.; Horne, J.C.; Wheeler, D.M.; Musgrave, C.E.

    1986-08-01

    During deposition of the Tensleep Formation, a shallow, semirestricted portion of a major seaway that occupied the geosynclinal area to the west extended into the area of the present-day Bighorn basin. Limiting the transgression of this sea was the Beartooth high on the north and the Bighorn high on the east and southeast. On the western side of the area, a southerly extension of the Yellowstone high restricted circulation. The lower Tensleep Formation (Desmoinesian), characterized by extensive marine influence, was deposited as coastal sand dunes and interdunes over subaerially exposed structural highs. These deposits grade basinward into shoreface sandstones, which in turn grade into sandstones and carbonates of the shelf environment. During deposition of upper Tensleep strata (Missourian through Virgilian), marine waters were less widespread. The Greybull arch, a northeast-trending feature in the northern part of the area, was uplifted, dividing the shallow sea into two parts. The upper Tensleep Formation was deposited as a terrestrial sand sea over the Bighorn high. Coastal dunes and interdunes were deposited seaward of the sand seas and over the Beartooth high, the Greybull arch, and the southerly extension of the Yellowstone high. These deposits grade basinward into clastic shoreface deposits. Following Tensleep deposition, the region underwent southward tilting, which caused exposure and erosion of the Tensleep Formation. The resulting unconformity surface was deeply incised by a dendritic drainage system that controlled the thickness of the formation. The Greybull arch and the Bighorn high acted as significant drainage divides, over which very little of the formation was preserved.

  9. Mosses Indicating Atmospheric Nitrogen Deposition and Sources in the Yangtze River Drainage Basin, China

    NASA Astrophysics Data System (ADS)

    Xiao, Hua-Yun; Tang, Cong-Guo; Xiao, Hong-Wei; Liu, Xue-Yan; Liu, Cong-Qiang

    2010-07-01

    Characterizing the level and sources of atmospheric N deposition in a large-scale area is not easy when using physical monitoring. In this study, we attempted to use epilithic mosses (Haplocladium microphyllum (Hedw.)) as a bioindicator. A gradient of atmospheric N deposition from 13.8 kg N ha-1 yr-1 to 47.7 kg N ha-1 yr-1 was estimated on the basis of moss tissue N concentrations and the linear equation between them. The estimated results are reliable because the highest atmospheric N deposition occurred in the middle parts of the Yangtze River, where the highest TN concentrations were also observed. Moss δ15N values in cities and forests were found in distinctly different ranges of approximately -10‰ to -6‰ and approximately -2‰ to 2‰, respectively, indicating that the main N sources in most of these cities were excretory wastes and those in forests were soil emissions. A negative correlation between moss δ15N values and the ratios of NH4-N/NO3-N in deposition (y = -1.53 x + 1.78) has been established when the ratio increased from 1.6 to 6.5. On the basis of the source information, the negative moss δ15N values in this study strongly indicate that NHy-N is the dominant N form in N deposition in the whole drainage basin. These findings are supported by the existing data of chemical composition of local N deposition.

  10. Sensitivity of stream basins in Shenandoah National Park to acid deposition

    USGS Publications Warehouse

    Lynch, D.D.; Dise, N.B.

    1985-01-01

    Six synoptic surveys of 56 streams that drain the Shenandoah National Park, Virginia, were conducted in cooperation with the University of Virginia to evaluate sensitivity of dilute headwater streams to acid deposition and to determine the degree of acidification of drainage basins. Flow-weighted alkalinity concentration of most streams is below 200 microequivalents per liter, which is considered the threshold of sensitivity. Streams draining resistant siliceous bedrocks have an extreme sensitivity (alkalinity below 20 microequivalents/L); those draining granite and granodiorite have a high degree of sensitivity (20 to 100 microequivalents/L); and streams draining metamorphosed volcanics have moderate to marginal sensitivity (100 to 200 microequivalents/L). A comparison of current stream water chemistry to that predicted by a model based on carbonic acid weathering reactions suggests that all basins in the Park shows signs of acidification by atmospheric deposition. Acidification is defined as a neutralization of stream water alkalinity and/or an increase in the base cation weathering rate. Acidification averages 50 microequivalents/L, which is fairly evenly distributed in the Park. However, the effects of acidification are most strongly felt in extremely sensitive basins, such as those underlain by the Antietam Formation, which have stream water pH values averaging 4.99 and a mineral acidity of 7 microequivalents/L. (USGS)

  11. Depositional history of the Mississippian Ullin and Fort Payne Formations in the Illinois Basin

    SciTech Connect

    Lasemi, Z.; Treworgy, J.D.; Norby, R.D. )

    1994-04-01

    Field and subsurface data suggest that the mid-Mississippian Ullin Limestone in the Illinois Basin is composed of coalesced Waulsortian-type mounds and porous bryozoan-dominated buildups. Waulsortian mounds in the basin contain a lime mudstone to wackestone core that is flanked and capped by in situ porous bryozoan bafflestone or transported crinoidal-bryozoan packstone and grainstone. The mound core facies appear to be most common in the lower part of the Ullin and is thicker in a deeper outer-ramp setting. Shoreward and up-section (upper part of the outer-ramp through mid-ramp setting), the core facies is generally thinner, while the flanking and capping facies are thicker. Isopachous maps of the Ullin and Fort Payne suggest the presence of several large areas of thick carbonate buildups (Ullin) surrounded by a deep-water, sub-oxic environment (Fort Payne) in the Illinois Basin. Progradation of these buildups and associated facies resulted in a shallower ramp setting during deposition of the upper Ullin. Storm-generated carbonate sandwaves became widespread on this ramp. Sandwaves were mobile and for the most part unfavorable sites for further development of thick mud mounds and/or in situ bryozoan buildups. However, isolated mounds and flanking buildups are present in the upper part of the Ullin, and, together with the sandwaves, formed an irregular topography that led to the development of oolitic grainstone shoals during deposition of the overlying Salem Limestone.

  12. Stratigraphy, depositional history, and petroleum geology of Lower Cretaceous Fall River formation, Powder River Basin, Wyoming

    SciTech Connect

    Ryer, T.A.; Gustason, E.R.

    1985-05-01

    The middle Albian Fall River Formation, better know to petroleum geologists as the Dakota Sandstone, constitutes a northwestward-thinning wedge of predominantly sandy strata under and overlain by marine shale. Two major episodes of deltaic progradation can be recognized in the formation, permitting mapping of lower and upper deltaic members. Study of outcrops, cores, and subsurface relationships indicates that the Fall River consists predominantly of fluvial strata in the southeastern part of the Powder River basin; delta-front and delta-plain facies, which are cut out and replaced locally by northwest-trending meander belts, predominate in an area that tends northeastward across the central part of the basin; the delta-front facies pinches out into offshore marine shale in the northwestern part of the basin. The large majority of Fall River stratigraphic trap-type fields produce oil and gas from sandy meander-belt deposits. The largest accumulations of hydrocarbons in traps of this type, as exemplified by the Powell-Mexican Springs trend (lower member) and the Coyote Creek-Miller Creek trend (upper member), occur in the more seaward parts of the deltaic members, near the seaward termini of meander-belt systems. Mapping of meander belts and of the surrounding deltaic deposits constitutes a necessary first step in exploration for stratigraphic traps within the Fall River Formation.

  13. Hydrology of marginal evaporitic basins during the Messinian Salinity Crisis: isotopic investigation of gypsum deposits

    NASA Astrophysics Data System (ADS)

    El Kilany, Aida; Caruso, Antonio; Dela Pierre, Francesco; Natalicchio, Marcello; Rouchy, Jean-Marie; Pierre, Catherine; Balter, Vincent; Aloisi, Giovanni

    2016-04-01

    The deposition of gypsum in Messinian Mediterranean marginal basins is controlled by basin restriction and the local hydrological cycle (evaporation/precipitation rates and relative importance of continental vs marine water inputs). We are using the stable isotopic composition of gypsum as a proxy of the hydrological cycle that dominated at the moment of gypsum precipitation. We studied the Messinian Caltanissetta (Sicily) and Tertiary Piedmont (north western Italy) basins where we carried out a high-resolution isotopic study of gypsum layers composing gypsum-marl cycles. These cycles are thought to be the sedimentary expression of astronomical precession cycles, lasting approximately 20 kyr, during which the marginal basins experienced a succession of arid and a wet conditions. We determined the isotopic composition of gypsum hydration water (18O and D), of the sulphate ion (34S, 18O) and of Strontium (87/86Sr), all of which are potentially affected by the hydrological cycle. In our samples, the mother water from which gypsum precipitated is considerably lighter (-4.0 < 18OH2O ‰ vs SMOW < 3.1; -34.8 < DH2O ‰ vs SMOW < 25.3) than evaporated marine waters from which gypsum precipitates (18OH2O  6-7 ‰ vs SMOW; DH2O  30-40‰ vs SMOW), suggesting that the marginal basins were receiving an input of continental water during gypsum precipitation. Moreover, the degree of 18O and D-depletion is basin-specific, which is consistent with the geographical distance between the two basins and their independent local climates and watersheds. Continental water inputs are consistent also with most of the Sr data (0.70861 < 87/86Sr < 0.70897), and with previously published low-salinity fluid inclusion data from the same gypsum layers in the Tertiary Piedmont basin (suggesting a salinity lower than 35 ‰ in many cases). However, in the samples from the Caltanissetta basin, the sulphate ion suggests a marine water source (20.7 < δ34S ‰ vs CTD

  14. Geologic Characterization of Young Alluvial Basin-Fill Deposits from Drill Hole Data in Yucca Flat, Nye County, Nevada.

    SciTech Connect

    Donald S. Sweetkind; Ronald M. Drake II

    2007-01-22

    Yucca Flat is a topographic and structural basin in the northeastern part of the Nevada Test Site (NTS) in Nye County, Nevada, that has been the site of numerous underground nuclear tests; many of these tests occurred within the young alluvial basin-fill deposits. The migration of radionuclides to the Paleozoic carbonate aquifer involves passage through this thick, heterogeneous section of Tertiary and Quaternary rock. An understanding of the lateral and vertical changes in the material properties of young alluvial basin-fill deposits will aid in the further development of the hydrogeologic framework and the delineation of hydrostratigraphic units and hydraulic properties required for simulating ground-water flow in the Yucca Flat area. This report by the U.S. Geological Survey, in cooperation with the U.S. Department of Energy, presents data and interpretation regarding the three-dimensional variability of the shallow alluvial aquifers in areas of testing at Yucca Flat, data that are potentially useful in the understanding of the subsurface flow system. This report includes a summary and interpretation of alluvial basin-fill stratigraphy in the Yucca Flat area based on drill hole data from 285 selected drill holes. Spatial variations in lithology and grain size of the Neogene basin-fill sediments can be established when data from numerous drill holes are considered together. Lithologic variations are related to different depositional environments within the basin including alluvial fan, channel, basin axis, and playa deposits.

  15. Geologic Characterization of Young Alluvial Basin-Fill Deposits from Drill-Hole Data in Yucca Flat, Nye County, Nevada

    USGS Publications Warehouse

    Sweetkind, Donald S.; Drake II, Ronald M.

    2007-01-01

    Yucca Flat is a topographic and structural basin in the northeastern part of the Nevada Test Site in Nye County, Nevada, that has been the site of numerous underground nuclear tests; many of these tests occurred within the young alluvial basin-fill deposits. The migration of radionuclides to the Paleozoic carbonate aquifer involves passage through this thick, heterogeneous section of Tertiary and Quaternary rock. An understanding of the lateral and vertical changes in the material properties of young alluvial basin-fill deposits will aid in the further development of the hydrogeologic framework and the delineation of hydrostratigraphic units and hydraulic properties required for simulating ground-water flow in the Yucca Flat area. This report by the U.S. Geological Survey, in cooperation with the U.S. Department of Energy, presents data and interpretation regarding the three-dimensional variability of the shallow alluvial aquifers in areas of testing at Yucca Flat, data that are potentially useful in the understanding of the subsurface flow system. This report includes a summary and interpretation of alluvial basin-fill stratigraphy in the Yucca Flat area based on drill-hole data from 285 selected drill holes. Spatial variations in lithology and grain size of the Neogene basin-fill sediments can be established when data from numerous drill holes are considered together. Lithologic variations are related to different depositional environments within the basin such as alluvial fan, channel, basin axis, and playa deposits.

  16. Geologic Characterization of Young Alluvial Basin-Fill Deposits from Drill Hole Data in Yucca Flat, Nye County, Nevada

    USGS Publications Warehouse

    Sweetkind, Donald S.; Drake II, Ronald M.

    2007-01-01

    Yucca Flat is a topographic and structural basin in the northeastern part of the Nevada Test Site (NTS) in Nye County, Nevada, that has been the site of numerous underground nuclear tests; many of these tests occurred within the young alluvial basin-fill deposits. The migration of radionuclides to the Paleozoic carbonate aquifer involves passage through this thick, heterogeneous section of Tertiary and Quaternary rock. An understanding of the lateral and vertical changes in the material properties of young alluvial basin-fill deposits will aid in the further development of the hydrogeologic framework and the delineation of hydrostratigraphic units and hydraulic properties required for simulating ground-water flow in the Yucca Flat area. This report by the U.S. Geological Survey, in cooperation with the U.S. Department of Energy, presents data and interpretation regarding the three-dimensional variability of the shallow alluvial aquifers in areas of testing at Yucca Flat, data that are potentially useful in the understanding of the subsurface flow system. This report includes a summary and interpretation of alluvial basin-fill stratigraphy in the Yucca Flat area based on drill hole data from 285 selected drill holes. Spatial variations in lithology and grain size of the Neogene basin-fill sediments can be established when data from numerous drill holes are considered together. Lithologic variations are related to different depositional environments within the basin including alluvial fan, channel, basin axis, and playa deposits.

  17. Late Permian Palynology and depositional environment of Chintalapudi sub basin, Pranhita-Godavari basin, Andhra Pradesh, India

    NASA Astrophysics Data System (ADS)

    Jha, Neerja; Pauline Sabina, K.; Aggarwal, Neha; Mahesh, S.

    2014-01-01

    The present study deals with the palynological dating, correlation and depositional setting of the sediments from bore cores MGP-11 and MGP-4 from Gauridevipet area of Chintalapudi sub-basin of Godavari master basin, south India. On the basis of palynological studies, three palynoassemblages have been identified, one in bore core MGP-11 a Faunipollenites (=Protohaploxypinus) and Striasulcites assemblage and two in bore core MGP-4; one is characterized by the dominance of striate bisaccates and Densipollenites and the other by Striatopodocarpites and Cresentipollenites palynoassemblages. The other stratigraphically significant taxa include Guttulapollenites hannonicus, Lunatisporites noviaulensis, Lunatisporites pellucidus, Densoisporites contactus, Chordasporites australiensis, Goubinispora spp., Lundbladispora microconata, Lundbladispora raniganjensis and Klausipollenites schaubergeri. The recovered taxa suggest a Late Permian, Lopingian age for these rocks. This interpretation is based on the correlation of the assemblages with similar assemblages from previous Gondwana studies chiefly Densipollenites magnicorpus Zone of Damodar Basin, India and Late Permian palynoassemblages from Africa, Antarctica, Australia and South America. On the basis of palaeobotanical affinity of the identified microflora it has been inferred that the peat forming plant community was composed mainly of gymnosperm pollen attributable to glossopterids, that includes striate and non-striate bisaccates and paucity of cordaites which includes monosaccates. Spores are subordinate and are derived from lycopsids (Lundbladispora, Densoisporites), sphenopsids (Latosporites) and filicopsids (Horriditriletes, Lophotriletes, Verrucosisporites, Osmundacidites, Leiotriletes, Callumispora, Brevitriletes and Microbaculispora) occurring in variable proportions. The dominance of subarborescent/arborescent vegetation suggests a development in a forest swamp probably in a small distant marginal part of the

  18. Anatomy of mass transport deposits in the Dead Sea: sedimentary processes in an active tectonic hypersaline basin

    NASA Astrophysics Data System (ADS)

    Waldmann, Nicolas; Hadzhiivanova, Elitsa; Neugebauer, Ina; Brauer, Achim; Schwab, Markus; Frank, Ute; Dulski, Peter

    2014-05-01

    Continental archives such as interplate endorheic lacustrine sedimentary basins provide an excellent source of data for studying regional climate, seismicity and environmental changes through time. Such is the case for the sediments that were deposited in the Dead Sea basin, a tectonically active pull-apart structure along the Dead Sea fault (DSF). This elongated basin is characterized by steep slopes and a deep and flat basin-floor, which are constantly shaped by seismicity and climate. In this study, we present initial results on the sedimentology and internal structure of mass transport deposits in the Pleistocene Dead Sea. The database used for this study consists of a long core retrieved at ~300 m water depth in the deepest part of the Dead Sea as part of an international scientific effort under the auspice of the ICDP. Micro-facies analysis coupled by elemental scanning (µXRF), granulometry and petrophysical measurements (magnetic susceptibility) have been carried out on selected intervals in order to decipher and identify the source-to-sink processes and controlling mechanisms behind the formation of mass transport deposits. The findings of this study allowed defining and characterizing the mass transport deposits into separate sedimentary facies according to the lake level and limnological conditions. Investigating sediments from the deep Dead Sea basin allowed better understanding and deciphering the depositional processes in relation with the tectonic forces shaping this basin.

  19. Tectonic pattern of the Mendeleev Ridge and adjacent basins: results of joint analysis of potential fields and recent Russian seismic data

    NASA Astrophysics Data System (ADS)

    Chernykh, Andrey; Astafurova, Ekaterina; Korneva, Maria; Egorova, Alena; Redko, Anton; Glebovsky, Vladimir

    2014-05-01

    The work was performed under Russian Federation State Geological mapping at a scale of 1:1 000 000 and UNCLOS programs. The study area is located between 76N-84N and 156E-168W and covers the Mendeleev Ridge, adjacent Podvodnikov, Mendeleev, Chukchi Basins and northern part of the East-Siberian Sea shelf. It is characterized by very poor magnetic and gravity data coverage. Majority of airborne magnetic and on-ice gravity surveys were carried out in the region about 40 years ago and have low spatial resolution and poor navigation. Seismic data collected earlier in the study area are presented by sparse lines of historical seismic reflection soundings and by results of deep seismic refraction and reflection observations along several geotransects. Hence, conclusions concerning tectonic structure and spatial relation of the Mendeleev Ridge with adjacent geological structures up to present day remain speculative. Joint analysis of recent seismic reflection and refraction data collected during Russian expeditions «Arctic-2011» and «Arctic-2012» with mentioned above geophysical information allowed to clarify the contours of geological structures in the study area and reveal some new peculiarities of their tectonic pattern. Particularly complex tectonic structure of the Mendeleev Ridge, changing from it's southern to the northern part and represented by two main systems of tectonic displacements is discovered. The first fault system comprises horsts/graben-bounding faults oriented preferably in N-S direction. The second system is presented by faults of NW-SE direction disturbing the first one. In the southern part of the Mendeleev Ridge such faults are the strike-slip faults with small horizontal displacements. Starting from the central part of the ridge and further to the north, displacements along strike-slip faults become progressively more pronounced and have sinistral character. In the northern part of the ridge a pull-apart structures are recognized which

  20. Depositional environments of the Santa Margarita Formation in the Miocene Santa Maria basin, Huasna syncline

    SciTech Connect

    Phillips, R.L. )

    1991-02-01

    Preliminary investigation of the depositional environments of the middle sandstone member of the late middle Miocene Santa Margarita Formation in the Huasna syncline suggests a current-dominated shallow shelf environment. Progradation of coarse-grained clastic and bioclastic-rich sediment over siltstone documents the initial stage of deposition of this sand body. Overlying the basal intensely bioturbated bioclastic sediments are large-scale tabular cross-beds, up to 16 m thick, interbedded with tabular lag deposits of barnacles, oysters, and echinoids. The tabular fossil-rich beds, which form sequences up to 6 m thick between the large-scale cross-beds, represent either deposition of bottom set beds of the large-scale cross-beds or current swept lag deposits. Increasing energy conditions are recorded vertically by a decrease in the amount of bioturbation and by an increase in large-scale cross-bed sets and cosets. however, in the northern outcrop area subtidal channels are incised into the upper bioclastic sediments suggesting local shoaling conditions. Paleocurrent data record a unidirectional southwest-directed current trend normal to the basin axis and the East Huasna fault. The coarse clastic deposition terminates with deposition of siltstone as energy conditions decreased and water depth again increased. A current-swept shallow shelf containing extensive sandwaves comprises the major depositional environments. The paleocurrent data and large-scale cross-beds suggest that the shallow shelf extended to the east of the Huasna syncline and that the currents were most likely tidal in origin.

  1. Mineral deposit formation in Phanerozoic sedimentary basins of north-east Africa: the contribution of weathering

    NASA Astrophysics Data System (ADS)

    Germann, Klaus; Schwarz, Torsten; Wipki, Mario

    1994-12-01

    The intra- and epicontinental basins in north-east Africa (Egypt, Sudan) bear ample evidence of weathering processes repeatedly having contributed to the formation of mineral deposits throughout the Phanerozoic. The relict primary weathering mantle of Pan-African basement rocks consists of kaolinitic saprolite, laterite (in places bauxitic) and iron oxide crust. On the continent, the reaccumulation of eroded weathering-derived clay minerals (mainly kaolinite) occurred predominantly in fluvio-lacustrine environments, and floodplain and coastal plain deposits. Iron oxides, delivered from ferricretes, accumulated as oolitic ironstones in continental and marine sediments. Elements leached from weathering profiles accumulated in continental basins forming silcrete and alunite or in the marine environment contributing to the formation of attapulgite/saprolite and phosphorites. The Early Paleozoic Tawiga bauxitic laterite of northern Sudan gives a unique testimony of high latitude lateritic weathering under global greenhouse conditions. It formed in close spatial and temporal vicinity to the Late Ordovician glaciation in north Africa. The record of weathering products is essentially complete for the Late Cretaceous/Early Tertiary. From the continental sources in the south to the marine sinks in the north, an almost complete line of lateritic and laterite-derived deposits of bauxitic kaolin, kaolin, iron oxides and phosphates is well documented.

  2. Saharan dust deposition in the Carpathian Basin and its possible effects on interglacial soil formation

    NASA Astrophysics Data System (ADS)

    Varga, György; Cserháti, Csaba; Kovács, János; Szalai, Zoltán

    2016-09-01

    Several hundred tons of windblown dust material are lifted into the atmosphere and are transported every year from Saharan dust source areas towards Europe having an important climatic and other environmental effect also on distant areas. According to the systematic observations of modern Saharan dust events, it can be stated that dust deflated from North African source areas is a significant constituent of the atmosphere of the Carpathian Basin and Saharan dust deposition events are identifiable several times in a year. Dust episodes are connected to distinct meteorological situations, which are also the determining factors of the different kinds of depositional mechanisms. By using the adjusted values of dust deposition simulations of numerical models, the annual Saharan dust flux can be set into the range of 3.2-5.4 g/m2/y. Based on the results of past mass accumulation rates calculated from stratigraphic and sedimentary data of loess-paleosol sequences, the relative contribution of Saharan dust to interglacial paleosol material was quantified. According to these calculations, North African exotic dust material can represent 20-30% of clay and fine silt-sized soil components of interglacial paleosols in the Carpathian Basin. The syngenetic contribution of external aeolian dust material is capable to modify physicochemical properties of soils and hereby the paleoclimatic interpretation of these pedogene stratigraphic units.

  3. 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.

  4. Spatial patterns of cadmium and lead deposition on and adjacent to National Park Service lands in the vicinity of Red Dog Mine, Alaska.

    PubMed

    Hasselbach, L; Ver Hoef, J M; Ford, J; Neitlich, P; Crecelius, E; Berryman, S; Wolk, B; Bohle, T

    2005-09-15

    Heavy metal escapement associated with ore trucks is known to occur along the DeLong Mountain Regional Transportation System (DMTS) haul road corridor in Cape Krusenstern National Monument, northwest Alaska. Heavy metal concentrations in Hylocomium splendens moss (n = 226) were used in geostatistical models to predict the extent and pattern of atmospheric deposition of Cd and Pb on Monument lands. A stratified grid-based sample design was used with more intensive sampling near mine-related activity areas. Spatial predictions were used to produce maps of concentration patterns, and to estimate the total area in 10 moss concentration categories. Heavy metal levels in moss were highest immediately adjacent to the DMTS haul road (Cd > 24 mg/kg dw; Pb > 900 mg/kg dw). Spatial regression analyses indicated that heavy metal deposition decreased with the log of distance from the DMTS haul road and the DMTS port site. Analysis of subsurface soil suggested that observed patterns of heavy metal deposition reflected in moss were not attributable to subsurface lithology at the sample points. Further, moss Pb concentrations throughout the northern half of the study area were high relative to concentrations previously reported from other Arctic Alaska sites. Collectively, these findings indicate the presence of mine-related heavy metal deposition throughout the northern portion of Cape Krusenstern National Monument. Geospatial analyses suggest that the Pb depositional area extends 25 km north of the haul road to the Kisimilot/Iyikrok hills, and possibly beyond. More study is needed to determine whether higher moss heavy metal concentrations in the northernmost portion of the study area reflect deposition from mining-related activities, weathering from mineralized Pb/Zn outcrops in the broader region, or a combination of the two. South of the DMTS haul road, airborne deposition appears to be constrained by the Tahinichok Mountains. Heavy metal levels continue to diminish south of

  5. Tectonic structure of Dokdo and adjacent area in the northeastern part of the Ulleung Basin of the East Sea using geophysical data

    NASA Astrophysics Data System (ADS)

    Kim, C.; Jeong, E.; Park, C.; Kwon, B.; Park, G.; Park, J.

    2008-12-01

    The northeastern part of the Ulleung Basin in the East Sea is composed of volcanic islands (Ulleungdo and Dokdo), seamounts (the Anyongbok Seamount, the Simheungtaek and the Isabu Tablemounts), and a deep pathway (Korea Gap). To understand tectonic structure and geophysical characteristics of Dokdo and adjacent area, We analysed geophysical potential data of KORDI(Korea Ocean Research and Development Institute), KIGAM(Korea Institute of Geoscience and Mineral Resources), and NORI(National Oceanographic Research Institute of Korea) around the Dokdo volcanic body except Ulleung Do because of empty data of its large island. Also, we eliminate the effect of water and sediments from the free-air gravity data to process 3D Moho depth inversion. 3D tectonic structure modelling of the study area was developed using Moho depth inversion result and sediment thickness data of NGDC(National Geophysical Data Center). The free-air gravity anomalies of the study area generally reflect bathymetric effects. Although the Dokdo seamounts have a similar topographic size, the decrease of free-air anomaly toward Isabu suggest that Isabu is oldest among the seaounts and have high degree of isostatic compensation. High Bouguer anomalies in the central part of the Ulleung Basin gradually decreases toward the Oki Bank. This feature suggests that the crust/mantle boundary is shallow in the central part of the Ulleung Basin. The complex magnetic pattern of Dokdo suggests that it might have erupted several times during its formation. The magnetic anomaly amplitude of Isabu is much smaller than that of Dokdo. Such low magnetic anomalies are attributed to a secondary change caused by the metamorphism or weathering of ferromagnetic minerals of the seamount during a long period of time after its formation. Analytic signals show high anomalous zones over volcanoes. Also, there are high analytic signal values in Korea Gap indicating magmatic intrusion in thick sediments. The power spectrum analysis

  6. Turonian-Santonian depositional and sea level history of the Tarfaya Atlantic coastal basin, SW Morocco

    NASA Astrophysics Data System (ADS)

    Aquit, Mohamed; Kuhnt, Wolfgang; Holbourn, Ann; Hassane Chellai, El; Lees, Jacqueline A.; Kluth, Oliver; Jabour, Haddou; Delaporte, Jean-Pierre

    2013-04-01

    The Turonian to Santonian organic-rich successions deposited in the continuously subsiding Tarfaya Atlantic coastal basin (SW Morocco) allow detailed reconstruction of depositional environments and correlation to eustatic sea level changes. We present high-resolution X-ray fluorescence (XRF) scanning and natural gamma-ray (NGR) records from a newly drilled sedimentary core Tarfaya SN°2 (27° 57´ 43.1´´N, 12° 48´ 37.0´´W), which recovered a continuous sedimentary succession from a middle to outer shelf environment. In the latest Turonian, the late Coniacian, and the middle and latest Santonian, high NGR and Al with low Mn and Ca content indicate pronounced dysoxic horizons that reflect impingement of the oxygen minimum zone on the shelf during sea level highstands. In contrast, lower NGR and Al with higher Mn and Ca values indicate high detrital carbonate content and more oxic conditions related to regressive events in the late Turonian, early to middle Conacian and early Santonian. Exceptionally high sedimentation rates (>10cm/kyr) characterize the late Turonian, and spectral analyses of XRF and NGR data reveal that sedimentation was mostly controlled by obliquity and precession, suggesting an overriding glacioeustatic control. However, the response to orbital forcing weakened during the latest Turonian, when sedimentation rates declined markedly to ~2 cm/kyr. We will extend this study to three newly drilled cores nearby that recovered sediment sequences from the late Albian to late Turonian and from the late Santonian to Campanian in order to retrace the complete Late Cretaceous depositional history of the Tarfaya Basin and to develop a high-resolution carbon isotope stratigraphy allowing correlation to records from other continental margins. Key words: Late Cretaceous, Tarfaya Basin, XRF scanning, natural gamma-ray, oxygen minimum zone, sea level, orbital forcing.

  7. DRY DEPOSITION OF AIRBORNE TRACE METALS ON THE LOS ANGELES BASIN AND ADJACENT COASTAL WATERS - ART. NO. 4074. (R825381)

    EPA Science Inventory

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  8. Water Resources of the Basin and Range Carbonate-Rock Aquifer System, White Pine County, Nevada, and Adjacent Areas in Nevada and Utah

    USGS Publications Warehouse

    Welch, Alan H.; Bright, Daniel J.; Knochenmus, Lari A.

    2008-01-01

    INTRODUCTION This report summarizes results of a water-resources study for White Pine County, Nevada, and adjacent areas in east-central Nevada and western Utah. The Basin and Range carbonate-rock aquifer system (BARCAS) study was initiated in December 2004 through Federal legislation (Section 301(e) of the Lincoln County Conservation, Recreation, and Development Act of 2004; PL108-424) directing the Secretary of the Interior to complete a water-resources study through the U.S. Geological Survey, Desert Research Institute, and State of Utah. The study was designed as a regional water-resource assessment, with particular emphasis on summarizing the hydrogeologic framework and hydrologic processes that influence ground-water resources. The study area includes 13 hydrographic areas that cover most of White Pine County; in this report however, results for the northern and central parts of Little Smoky Valley were combined and presented as one hydrographic area. Hydrographic areas are the basic geographic units used by the State of Nevada and Utah and local agencies for water-resource planning and management, and are commonly defined on the basis of surface-water drainage areas. Hydrographic areas were further divided into subbasins that are separated by areas where bedrock is at or near the land surface. Subbasins are the subdivisions used in this study for estimating recharge, discharge, and water budget. Hydrographic areas are the subdivision used for reporting summed and tabulated subbasin estimates.

  9. Water Resources of the Basin and Range Carbonate-Rock Aquifer System, White Pine County, Nevada, and Adjacent Areas in Nevada and Utah - Draft Report

    USGS Publications Warehouse

    Welch, Alan H.; Bright, Daniel J.

    2007-01-01

    Summary of Major Findings This report summarizes results of a water-resources study for White Pine County, Nevada, and adjacent areas in east-central Nevada and western Utah. The Basin and Range carbonate-rock aquifer system (BARCAS) study was initiated in December 2004 through Federal legislation (Section 131 of the Lincoln County Conservation, Recreation, and Development Act of 2004) directing the Secretary of the Interior to complete a water-resources study through the U.S. Geological Survey, Desert Research Institute, and State of Utah. The study was designed as a regional water-resource assessment, with particular emphasis on summarizing the hydrogeologic framework and hydrologic processes that influence ground-water resources. The study area includes 13 hydrographic areas that cover most of White Pine County; in this report however, results for the northern and central parts of Little Smoky Valley were combined and presented as one hydrographic area. Hydrographic areas are the basic geographic units used by the State of Nevada and Utah and local agencies for water-resource planning and management, and are commonly defined on the basis of surface-water drainage areas. Hydrographic areas were further divided into subbasins that are separated by areas where bedrock is at or near the land surface. Subbasins represent subdivisions used in this study for estimating recharge, discharge, and water budget. Hydrographic areas represent the subdivision used for reporting summed and tabulated subbasin estimates.

  10. The Bartonian organic-rich deposits within the Silesian Basin (Polish Outer Carpathians)

    NASA Astrophysics Data System (ADS)

    Waskowska, Anna; Golonka, Jan; Bębenek, Sławomir; Cieszkowski, Marek; Chodyń, Rafał; Kaminski, Michael

    2016-04-01

    The Silesian Basin developed in the Western part of the Carpathian Tethys during the Jurassic - Early Miocene times. Its size and bathymetry changed and the sedimentation took place in different environments during these times. The dark deposits rich in organic matter were widely distributed twice, first in the Early Cretaceous during the sedimentation of the Verovice Formation, and again in the latest Eocene - Early Oligocene when the Menilite Formation was deposited. The sedimentary successions of these formations are dominated by shales that originated in anoxic or dysoxic conditions. Similar deposits are present in the Bartonian and crop out in the Szczyrzyc Depression within the Silesian Nappe. They are represented by shales dominated by dark deposits rich in organic matter and contain several 0,5-3 mm thick layers of creamy bentonites. Brown mudstones prevail, they are laminated with intercalations of grey-green mudstones. The very fine-grained massive or parallel-laminated quartzite sandstones, hard brown siltstones, or sphaerosiderites occur as rare intercalations. The TOC content is usually 1-2%, in the uppermost part of the dark deposits complex TOC reaches 3%, while the surrounding deposits contain only 0.1-0.3 % . The foraminifera were used for age estimations. Assemblages from the dark deposits are poorly taxonomically diversified and contain agglutinated foraminifera represented by long-range cosmopolitan forms. It is possible to distinguish the lower part of the Ammodiscus latus biozone (after zonations by Geroch & Nowak 1984 and Olszewska, 1997 for the Carpathians) of Bartonian age taking into account the foraminiferal data from under- and overlying deposits. Low diversity and numbers of foraminifera is connected with low oxygen conditions in the bottom of the Silesian Basin. Concentration of organic matter in deep water conditions took place under certain conditions, like a low-energy environment with very low delivery of clastic material. These

  11. Depositional and tectonic framework of the rift basins of Lake Baikal from multichannel seismic data

    USGS Publications Warehouse

    Hutchinson, D.R.; Golmshtok, A.J.; Zonenshain, L.P.; Moore, T.C.; Scholz, C.A.; Klitgord, Kim D.

    1992-01-01

    Recent multichannel seismic reflection data from Lake Baikal, located in a large, active, continental rift in central Asia, image three major stratigraphic units totalling 3.5 to 7.5 km thick in four subbasins. A major change in rift deposition and faulting between the oldest and middle-rift units probably corresponds to the change from slow to fast rifting. A brief comparison of the basins of Lake Baikal with those of the East African rift system highlights differences in structural style that can be explained by differences in age and evolution of the surrounding basement rocks. -from Authors

  12. Significances of Radiocarbon Dating on Lake Deposits in Salton Basin, California

    NASA Astrophysics Data System (ADS)

    Li, H.; Xu, X.

    2006-12-01

    During the past four years, we have made 37 AMS C-14 measurements on samples including lake tufa, mollusk shell and charcoal from the ancient Lake Cahuilla, Salton Basin, California. A barnacle shell deposited in 1940 in Salton Sea has radiocarbon age of 160 yr BP, reflecting that the effect of reservoir age on the dating is minor. A bi-valve shell with the calibrated radiocarbon age of 42345 yr BP from the lake's east shore shows that the lake was established at least 40kyr ago. A 64-cm thick tufa slab (LC-1 collected from Travertine Point on the western shoreline has 15 AMS C-14 dates ranging from 1310 to 17840 yr BP with a good age sequence. Three gastropod shells incased in tufas at the 12-m shoreline in the same site have ages of 1390 to 1660 yr BP. These dates indicate that the lake was experienced more alkaline and saline conditions after 18ka and the lake level dropped below the level of LC-1 (-24 m a.s.l.) about 1300 years ago. SST-5, a 38-cm thick tufa slab collected from the 12-m shoreline at Old Pacific Railroad Station, has 9 AMS C-14 dates ranging from 1265 to 7080 yr BP with a good age sequence. An archaeological site, ~40m below SST-5, shows that a charcoal sample has a C-14 date of 575 yr BP and a bivalve shell below the charcoal has a C-14 date of 920 yr BP. Five AMS C-14 dates of SST-1, a 19-cm thick tufa slab collected from the 12-m shoreline in Lake Cahuilla County Park, exhibit the tufa deposited from 4790 to 1365 yr BP. A bivalve shell near SST-1 has a radiocarbon age of 1625 yr BP. At this site, there are tufa traps for fishing made by ancient Indians. The above dates reveal that Lake Cahuilla in the Salton Basin had a continuous history certainly longer than 20 kyrs, probably >40 kyrs. The lake deposits are able to provide information on (1) hydrological change in the Salton Basin; (2) connection between Colorado River and Salton Basin; (3) climate change in the Colorado Drainage basin; (4) westerly jet stream shift and variation of North

  13. Microfacies, depositional models and diagenesis of Lagoa Feia Formation (lower cretaceous), Campos Basin, offshore Brazil

    NASA Astrophysics Data System (ADS)

    Bertani, R. T.

    The Lagoa Feia Formation consists of the sediments deposited during the rift valley stage of the Campos Basin, varying from 200m to more than 1500m in thickness. In this unit seventeen microfacies were recognized, grouped into four main sequences, respectively dominated by terrigenous supplies, ostracods, pelecypods, and basic volcaniclastics. The vertical sequence of microfacies and the associations of syndepositional diagenetic minerals were used to reconstruct the general environment of deposition. Five diagenetic stages were recognized. Pelecypod rich microfacies present the highest potential for development of intraparticle and moldic secondary porosity. Two types of fabric selective porosity were experimentally developed in low porosity samples under simulated burial conditions. Intercrystal microporosity was formed by preferential dissolution of micrite size calcite compared to coarse calcite crystals of sparite and neomorphosed bioclasts, and intraparticle porosity was developed in pelecypod shells by selective dissolution of neomorphic calcite compared to sparite cement.

  14. Palynostratigraphy and sedimentary facies of Middle Miocene fluvial deposits of the Amazonas Basin, Brazil

    NASA Astrophysics Data System (ADS)

    Dino, Rodolfo; Soares, Emílio Alberto Amaral; Antonioli, Luzia; Riccomini, Claudio; Nogueira, Afonso César Rodrigues

    2012-03-01

    Palynostratigraphic and sedimentary facies analyses were made on sedimentary deposits from the left bank of the Solimões River, southwest of Manaus, State of Amazonas, Brazil. These provided the age-dating and subdivision of a post-Cretaceous stratigraphic succession in the Amazonas Basin. The Novo Remanso Formation is subdivided into upper and lower units, and delineated by discontinuous surfaces at its top and bottom. The formation consists primarily of sandstones and minor mudstones and conglomerates, reflecting fluvial channel, point bar and floodplain facies of a fluvial meandering paleosystem. Fairly well-preserved palynoflora was recovered from four palynologically productive samples collected in a local irregular concentration of gray clay deposits, rich in organic material and fossilized wood, at the top of the Novo Remanso Formation upper unit. The palynoflora is dominated by terrestrial spores and pollen grains, and is characterized by abundant angiosperm pollen grains ( Tricolpites, Grimsdalea, Perisyncolporites, Tricolporites and Malvacearumpollis). Trilete spores are almost as abundant as the angiosperm pollen, and are represented mainly by the genera Deltoidospora, Verrutriletes, and Hamulatisporis. Gymnosperm pollen is scarce. The presence of the index species Grimsdalea magnaclavata Germeraad et al. (1968) indicates that these deposits belong to the Middle Miocene homonymous palynozone (Lorente, 1986; Hoorn, 1993; Jaramillo et al., 2011). Sedimentological characteristics (poorly sorted, angular to sub-angular, fine to very-coarse quartz sands facies) are typical of the Novo Remanso Formation upper part. These are associated with a paleoflow to the NE-E and SE-E, and with an entirely lowland-derived palinofloristic content with no Andean ferns and gymnosperms representatives. All together, this suggests a cratonic origin for this Middle Miocene fluvial paleosystem, which was probably born in the Purus Arch eastern flank and areas surrounding the

  15. Occurrence and seismic characteristics of stacked Quaternary debris-flow deposits in the Ulleung Basin, East Sea

    NASA Astrophysics Data System (ADS)

    Yoo, Dong-Geun; Lee, Young-Mi; Kang, Nyeon-Keon; Yi, Bo-Yeon; Bahk, Jang-Jun; Kim, Gil-Young

    2015-04-01

    Analysis of multi-channel seismic reflection profiles collected from the Ulleung Basin, East Sea reveals that the Quaternary sequence in this area includes eighteen stacked debris flow deposits, which are variable in the geometry and spatial distribution. Each deposit is acoustically characterized by chaotic or transparent seismic facies without distinct internal reflections and shows wedge or lens-shaped external form. Based on distribution patterns, these deposits which form a succession of vertically and/or laterally stacked wedges are widely distributed on the southern slope and cover an area of more than 8,000 km2. Their general flow direction is from south to north and the thickness gradually decreases toward the basin plain. The results of seismic interpretation suggest that sedimentation during the Quaternary was controlled mainly by tectonic effects associated with sea-level fluctuations. The back-arc closure of the East Sea that began in the Miocene caused compressional deformation along the southern margin of the Ulleung Basin, resulting in regional uplift which continued until the Pliocene. Large amounts of sediments, eroded from the uplifted blocks, were supplied to the basin through the mass transport processes, leading to the formation of stacked debris-flow deposits. Consequently, the development of debris flow deposits in the Ulleung Basin is largely controlled by regional tectonic event associated with the back-arc closure of the East Sea.

  16. High temperature polymetallic sulfide deposits in back arc environment: Lau basin SW Pacific

    SciTech Connect

    Fouquet, Y. ); Von Stackelberg, U. ); Herzig, P. )

    1990-06-01

    During the French-German diving cruise Nautilau, black smokers were observed for the first time in a back-arc environment. Twenty-two dives have been completed to investigate the southern Lau basin. The objectives were to understand the genesis of sulfide ores, the volcanic and tectonic activity in a back arc close to an island arc. The four diving sites in a water depth of about 2,000 m are located between 21{degree}25'S and 22{degree}40'S. Three types of hydrothermal deposits were discovered during the cruise: (1) Low temperature (40{degree}) deposits that are related to discharge through highly vesicular andesite and dacite. They are characterized by extensive deposits of Fe-Mn oxides underlaid by sulfides. (2) Medium- to high-temperature barite/sulfides mineralization was observed in many places along the ridge. The most important field, a few hundred meters in diameter and 20 m high, consists of barite chimneys and massive barite boulders mixed with massive sulfides. (3) Very high temperature black and white smokers were discovered at the central Valu Fa Ridge. The chemistry of the fluid and the plume is described elsewhere. The temperature measured at the vents (342{degree}C) and the general anomalies of the bottom seawater (up to 25{degree}C) indicate that the area is one of the most active known in the oceans at the present time. A complete cross section was sampled through a massive sulfide deposit including the stockwork.

  17. Regional tectonic influence on Early Cretaceous depositional patterns in Powder River basin, Wyoming and Montana

    SciTech Connect

    Bryan, J.G.; Petta, T.J.

    1988-01-01

    Integration of gravity, magnetic, seismic, and subsurface data from the Powder River basin indicates left-lateral wrenching caused principal and secondary shear compression to develop along northwest and east trends, respectively. This well-documented strain fabric caused by Laramide events has affected basin morphology and depositional patterns within the basin since the Early Cretaceous. Regional lineaments mapped at the surface have vertical displacements of tens of feet. These slightly displaced features can be correlated with wrench-related synthetic and antithetic fractures that display miles of subsurface lateral displacement. Results of detailed integrated forward modeling indicate these fractured zones had a significant effect on the distribution of Lower Cretaceous reservoir sands. Case histories from Buck Draw (Dakota Formation) and Bell Creek (Muddy Sandstone) fields illustrate how the consideration of basement tectonic influence is important to the proper evaluation of exploration leads. Proper use of all available data is essential to the reduction of exploratory risk and can aid in planning offset locations.

  18. Origin of tuff deposits in the lower Miocene Lospe Formation, Santa Maria basin, California

    SciTech Connect

    Cole, R.B. ); Stanley, R.G. ); Johnson, S.Y. )

    1991-02-01

    The Lospe Formation contains at least five mappable tuff units (17-18 Ma) which were erupted during initial stages of Neogene Santa Maria basin subsidence. Individual tuff units are lenticular, as much as 15-20 m thick, and 1-3 km wide; they were deposited predominantly in a lacustrine setting. Subaqueous deposition is indicated by facies of the interbedded nonvolcanic Lospe Formation. The lowermost Lospe Tuff unit, however, which overlies Jurassic basement, is interpreted as a subaerial deposit. Each subaqueous tuff unit contains two or more eruption units. Each eruption unit consists of three zones which are, from base to top: (1) massive vitric tuff comprising about 50% of the eruption unit, (2) thin- to medium-bedded vitric tuff with pumice concentrations at the tops of beds and mud drapes between beds, and (3) a thin-bedded interval of massive to planar laminated tuffaceous siltstone-mudstone. The predominance of delicate cuspate vitric shards and pumice, and the near absence of nonvolcanic detritus indicates that little or no reworking of the ash occurred prior to deposition. The Lospe tuffs are predominantly distal pyroclastic flow (zones 1 and 2) and pyroclastic turbidite (zones 2 and 3) deposits, derived from subaerial magmatic eruptions. A possible source for the Lospe tuffs is located at Tranquillon Mountain, 30 km to the south in the westernmost Transverse Range, where 17-18 Ma proximal pyroclastic deposits of welded lithic tuff breccia and thick pumiceous fallout tuffs are present. The similar ages, stratigraphic positions, and petrology, as well as the lateral facies relations suggests a correlation between the Tranquillon volcanic center and the Lospe tuff units. The authors are currently testing this hypothesis on the basis of geochemical and isotopic analyses.

  19. Petrology, depositional environments and structural development of the Mineta Formation, Teran Basin, Cochise County, Arizona

    NASA Astrophysics Data System (ADS)

    Grover, Jeffrey A.

    1984-03-01

    The Oligocene Mineta Formation of the Teran Basin in southeastern Arizona contains approximately 1000 m of interfingering alluvial-fan, fluvial, and lacustrine strata with minor intercalated volcanics. Sedimentation began prior to the middle Oligocene and ended with the eruption of the Oligocene-Miocene Galiuro Volcanics about 28 m.y. ago. Several related depositional facies are present in a cyclic pattern within the Mineta Formation. A complete cycle contains proximal, coarse-grained alluvial-fan conglomerates that fine upward into sandstone and pebble conglomerate of a distal-fan or braided-stream environment. Medium- to fine-grained sandstones are interpreted as sandflat deposits that lie stratigraphically above the distal-fan deposits and below lacustrine sandstone and algal limestone. The cycle culminates with deeper water lacustrine mudstone with intercalated thin-bedded turbidite sandstone. Discrete cycles of bedded gypsum and mudstone are found locally within the lacustrine deposits. These deposits represent a temporary playa-lake phase of the Mineta depositional system. The Mineta Formation filled a half-graben that developed in response to extensional stresses associated with the development of the Rincon/Catalina metamorphic core complex. Paleocurrents flowed southwestward from a source area of predominantly sedimentary and volcanic rocks. Sedimentation was contemporaneous with extensional deformation that produced low-angle normal faults and tilted the section toward the northeast. Maximum extension was directed about N55°E-S55°W, roughly parallel to the direction of paleocurrent flow, parallel to the mean slip direction for low-angle normal faults and perpendicular to the strike of the Mineta section.

  20. Characterization of the Hosgri Fault Zone and adjacent structures in the offshore Santa Maria Basin, south-central California: Chapter CC of Evolution of sedimentary basins/onshore oil and gas investigations - Santa Maria province

    USGS Publications Warehouse

    Willingham, C. Richard; Rietman, Jan D.; Heck, Ronald G.; Lettis, William R.

    2013-01-01

    The Hosgri Fault Zone trends subparallel to the south-central California coast for 110 km from north of Point Estero to south of Purisima Point and forms the eastern margin of the present offshore Santa Maria Basin. Knowledge of the attributes of the Hosgri Fault Zone is important for petroleum development, seismic engineering, and environmental planning in the region. Because it lies offshore along its entire reach, our characterizations of the Hosgri Fault Zone and adjacent structures are primarily based on the analysis of over 10,000 km of common-depth-point marine seismic reflection data collected from a 5,000-km2 area of the central and eastern parts of the offshore Santa Maria Basin. We describe and illustrate the along-strike and downdip geometry of the Hosgri Fault Zone over its entire length and provide examples of interpreted seismic reflection records and a map of the structural trends of the fault zone and adjacent structures in the eastern offshore Santa Maria Basin. The seismic data are integrated with offshore well and seafloor geologic data to describe the age and seismic appearance of offshore geologic units and marker horizons. We develop a basin-wide seismic velocity model for depth conversions and map three major unconformities along the eastern offshore Santa Maria Basin. Accompanying plates include maps that are also presented as figures in the report. Appendix A provides microfossil data from selected wells and appendix B includes uninterpreted copies of the annotated seismic record sections illustrated in the chapter. Features of the Hosgri Fault Zone documented in this investigation are suggestive of both lateral and reverse slip. Characteristics indicative of lateral slip include (1) the linear to curvilinear character of the mapped trace of the fault zone, (2) changes in structural trend along and across the fault zone that diminish in magnitude toward the ends of the fault zone, (3) localized compressional and extensional structures

  1. Nahcolite and halite deposition through time during the saline mineral phase of Eocene Lake Uinta, Piceance Basin, western Colorado

    USGS Publications Warehouse

    Johnson, Ronald C.; Brownfield, Michael E.

    2013-01-01

    Halite and the sodium bicarbonate mineral nahcolite were deposited during the saline phase of Eocene Lake Uinta in the Piceance Basin, western Colorado. Variations in the area of saline mineral deposition through time were interpreted from studies of core and outcrop. Saline minerals were extensively leached by groundwater, so the original extent of saline deposition was estimated from the distribution of empty vugs and collapse breccias. Vugs and breccias strongly influence groundwater movement, so determining where leaching has occurred is an important consideration for in-situ oil shale extraction methods currently being developed. Lake Uinta formed when two smaller fresh water lakes, one in the Uinta Basin of eastern Utah and the other in the Piceance Basin of western Colorado, expanded and coalesced across the Douglas Creek arch, an area of comparatively low subsidence rates. Salinity increased shortly after this expansion, but saline mineral deposition did not begin until later, after a period of prolonged infilling created broad lake-margin shelves and a comparatively small deep central lake area. These shelves probably played a critical role in brine evolution. A progression from disseminated nahcolite and nahcolite aggregates to bedded nahcolite and ultimately to bedded nahcolite and halite was deposited in this deep lake area during the early stages of saline deposition along with rich oil shale that commonly shows signs of slumping and lateral transport. The area of saline mineral and rich oil shale deposition subsequently expanded, in part due to infilling of the compact deep area, and in part because of an increase in water flow into Lake Uinta, possibly due to outflow from Lake Gosiute to the north. Finally, as Lake Uinta in the Piceance Basin was progressively filled from north to south by volcano-clastic sediment, the saline depocenter was pushed progressively southward, eventually covering much of the areas that had previously been marginal shelves

  2. U-Pb ages on single detrital zircon grains from the Witwatersrand Basin, South Africa: Constraints on the age of sedimentation and on the evolution of granites adjacent to the basin

    SciTech Connect

    Robb, L.J. ); Davis, D.W.; Kamo, S.L. )

    1990-05-01

    U-Pb ages of single detrital zircon grains from various stratigraphic horizons in the Dominion and Witwatersrand sequences provide constraints on the maximum age of sedimentation as well as indicating the pattern of age distribution in the (granitoid) source area providing detritus into the basin. Zircon ages in the Dominion sediments range from 3,191-3,105 Ma with a geometric mean ({bar X}) t 3,153 Ma. Those from the lower Witwatersrand sediments (West Rand Group) range from 3,305-3,044 Ma with {bar X} = 3,097 Ma, and zircons in the upper Witwatersrand sediments (Central Rand Group) are between 3,207-2,894 Ma old with {bar X} = 3,053 Ma. Ages of detrital zircons generally decrease upward in the stratigraphic record, and <3,000 Ma old zircons are only found in the Central Rand Group. This trend implies that younger granites may have formed at some time subsequent to lower Witwatersrand deposition, or that continued erosion of the hinterland resulted in the unroofing of successively younger granites. The wide spread of zircon ages (411 Ma) evident in the data set indicates that granites formed virtually continuously between circa 3,300-2.900 Ma in the Witwatersrand source area. Of the zircon ages 45% fall within 30 m.y. of the geometric mean of the total data set, suggesting that a major crust-forming event occurred at 3,073 {plus minus} 30 Ma. Granitoids in the source area can be divided into (i) pre-Dominion basement; (ii) Dominion granites, whose emplacement coincided with the extrusion of Dominion volcanics, and (iii) Randian granites, which were emplaced synchronously with Witwatersrand deposition. This sequence of events supports recent tectonic models that view the Witwatersrand sequence as having been deposited in a foreland basin.

  3. Carbonate deposition, Pyramid Lake subbasin, Nevada: 2. Lake levels and polar jet stream positions reconstructed from radiocarbon ages and elevations of carbonates (tufas) deposited in the Lahontan basin

    USGS Publications Warehouse

    Benson, L.; Kashgarian, Michaele; Rubin, M.

    1995-01-01

    Most of the tufas in the Pyramid Lake subbasin were deposited within the last 35 000 yr, including most of the mound tufas that border the existing lake. Many of the older tufas (>21 000 yr BP) contained in the mounds were formed in association with groundwater discharge. Lake Lahontan experienced large and abrupt rises in level that are believed to indicate the passage of the polar jet stream over the Lahontan basin. During expansion of the Laurentide Ice Sheet, the jet stream moved south across the basin, and during the contraction of the Ice Sheet, the jet stream moved north across the basin. The bulk of the carbonate contained in the mound tufas was deposited during the last major lake cycle (~23 500-12 000 yr BP), indicating that ground- and surface-water discharges increased at ~23 500 and decreased at ~ 12 000 yr BP. -from Authors

  4. Influence of depositional environment and diagenesis on gas reservoir properties in St. Peter Sandstone, Michigan basin

    SciTech Connect

    Harrison, W.B. III; Turmelle, T.M.; Barnes, D.A.

    1987-05-01

    The St. Peter Sandstone in the Michigan basin subsurface is rapidly becoming a major exploration target for natural gas. This reservoir was first proven with the successful completion of the Dart-Edwards 7-36 (Falmouth field, Missaukee County, Michigan) in 1981. Fifteen fields now are known, with a maximum of three producing wells in any one field. The production from these wells ranges from 1 to more than 10 MMCFGD on choke, with light-gravity condensate production of up to 450 b/d. Depth to the producing intervals ranges from about 7000 ft to more than 11,000 ft. The St. Peter Sandstone is an amalgamated stack of shoreface and shelf sequences more than 1100 ft in thickness in the basin center and thinning to zero at the basin margins. Sandstone composition varies from quartzarenite in the coarser sizes to subarkose and arkose in the finer sizes. Thin salty/shaly lithologies and dolomite-cemented sandstone intervals separate the porous sandstone packages. Two major lithofacies are recognized in the basin: a coarse-grained, well-sorted quartzarenite with various current laminations and a fine-grained, more poorly sorted subarkose and arkose with abundant bioturbation and distinct vertical and horizontal burrows. Reservoir quality is influenced by original depositional and diagenetic fabrics, but there is inversion of permeability and porosity with respect to primary textures in the major lithofacies. The initially highly porous and permeable, well-sorted, coarser facies is now tightly cemented with syntaxial quartz cement, resulting in a low-permeability, poor quality reservoir. The more poorly sorted, finer facies with initially lower permeabilities did not receive significant fluid flux until it passed below the zone of quartz cementation. This facies was cemented with carbonate which has subsequently dissolved to form a major secondary porosity reservoir.

  5. Hydrothermal dolomitization of basinal deposits controlled by a synsedimentary fault system in Triassic extensional setting, Hungary

    NASA Astrophysics Data System (ADS)

    Hips, Kinga; Haas, János; Győri, Orsolya

    2016-06-01

    Dolomitization of relatively thick carbonate successions occurs via an effective fluid circulation mechanism, since the replacement process requires a large amount of Mg-rich fluid interacting with the CaCO3 precursor. In the western end of the Neotethys, fault-controlled extensional basins developed during the Late Triassic spreading stage. In the Buda Hills and Danube-East blocks, distinct parts of silica and organic matter-rich slope and basinal deposits are dolomitized. Petrographic, geochemical, and fluid inclusion data distinguished two dolomite types: (1) finely to medium crystalline and (2) medium to coarsely crystalline. They commonly co-occur and show a gradual transition. Both exhibit breccia fabric under microscope. Dolomite texture reveals that the breccia fabric is not inherited from the precursor carbonates but was formed during the dolomitization process and under the influence of repeated seismic shocks. Dolomitization within the slope and basinal succession as well as within the breccia zones of the underlying basement block is interpreted as being related to fluid originated from the detachment zone and channelled along synsedimentary normal faults. The proposed conceptual model of dolomitization suggests that pervasive dolomitization occurred not only within and near the fault zones. Permeable beds have channelled the fluid towards the basin centre where the fluid was capable of partial dolomitization. The fluid inclusion data, compared with vitrinite reflectance and maturation data of organic matter, suggest that the ascending fluid was likely hydrothermal which cooled down via mixing with marine-derived pore fluid. Thermal gradient is considered as a potential driving force for fluid flow.

  6. Sequence stratigraphy and depositional controls in late Proterozoic-early Cambrian sediments of Amadeus basin, central Australia

    SciTech Connect

    Lindsay, J.F.

    1987-11-01

    The Amadeus basin is an isolated intracratonic basin at the center of the Australian continent which, because of its location and geometry, provides an ideal opportunity to investigate depositional controls. To this end, more than 6000 km of seismic data, in conjunction with a field and well-log program, have been used in a study of the late Proterozoic-Early Cambrian Arumbera Sandstone. 17 figures.

  7. Sugmut field: A forced regression deposit within the Neocomian prograding clinoform complex, West Siberian Basin, Russia

    SciTech Connect

    Armentrout, J.M. ); Oleg, M.; Igirgi, M.

    1996-01-01

    The Volgian-Neocomian interval of the Middle Ob Region of the intracratonic West Siberian Basin consists of between 35 and 45 regional transgressive/regressive cycles infilling a basin which had an average water depth of approximately 200 meters. Within local clinoforms, wells have encountered elongate shelf-edge sandstone bodies ranging from 15 to 100 kilometers in strike-oriented length. In most areas the seismic interval correlative to the reservoir sandstone pinches-out against the foreset of the preceding clinoform. This geometric relationship, and the sharp-based log pattern of sandstones along the more landward margin of the sandstone body, suggests that the sandstone may have been deposited as a consequence of marked downward shift in baselevel as part of a lowstand prograding complex, or possibly as a late highstand forced regression deposit. The Sugmut field, located in the northeast part of the study area, is 12 km wide east-west and 75 km long north-south, and grades laterally into shale to the west, south and east. Relative to the regressive phase isopach, the transgressive phase isopach thick shifts slightly northward and eastward indicating the direction of littoral drift and marginward transgression. In the northern part of the field the shelf-edge sandstone interval may correlate with a thin depositional-dip oriented shelf sandstone mapped within the transgressive interval. This mapped pattern may be interpreted as lowstand incision of a fluvial system supplying sand to a shelf-edge delta followed by infilling of the fluvial valley during transgression. Subsequent down-to-the-north regional tilt resulted in structural closure forming the Sugmut field trap.

  8. Sugmut field: A forced regression deposit within the Neocomian prograding clinoform complex, West Siberian Basin, Russia

    SciTech Connect

    Armentrout, J.M.; Oleg, M.; Igirgi, M.

    1996-12-31

    The Volgian-Neocomian interval of the Middle Ob Region of the intracratonic West Siberian Basin consists of between 35 and 45 regional transgressive/regressive cycles infilling a basin which had an average water depth of approximately 200 meters. Within local clinoforms, wells have encountered elongate shelf-edge sandstone bodies ranging from 15 to 100 kilometers in strike-oriented length. In most areas the seismic interval correlative to the reservoir sandstone pinches-out against the foreset of the preceding clinoform. This geometric relationship, and the sharp-based log pattern of sandstones along the more landward margin of the sandstone body, suggests that the sandstone may have been deposited as a consequence of marked downward shift in baselevel as part of a lowstand prograding complex, or possibly as a late highstand forced regression deposit. The Sugmut field, located in the northeast part of the study area, is 12 km wide east-west and 75 km long north-south, and grades laterally into shale to the west, south and east. Relative to the regressive phase isopach, the transgressive phase isopach thick shifts slightly northward and eastward indicating the direction of littoral drift and marginward transgression. In the northern part of the field the shelf-edge sandstone interval may correlate with a thin depositional-dip oriented shelf sandstone mapped within the transgressive interval. This mapped pattern may be interpreted as lowstand incision of a fluvial system supplying sand to a shelf-edge delta followed by infilling of the fluvial valley during transgression. Subsequent down-to-the-north regional tilt resulted in structural closure forming the Sugmut field trap.

  9. Characterization of geologic deposits in the vicinity of US Ecology, Amargosa Basin, southern Nevada

    USGS Publications Warehouse

    Taylor, Emily M.

    2010-01-01

    Multiple approaches have been applied to better understand the characteristics of geologic units exposed at the surface and buried at depth in the vicinity of US Ecology (USE), a low-level commercial waste site in the northern Amargosa Desert, Nevada. Techniques include surficial geologic mapping and interpretation of the subsurface using borehole data. Dated deposits at depth were used to estimate rates of sediment accumulation. The subsurface lithologies have been modeled in three dimensions. Lithologic cross sections have been created from the three-dimensional model and have been compared to resistivity data at the same location. Where deposits appear offset, a fault was suspected. Global Positioning System elevation transects were measured and trenches were excavated to locate a strand of the Carrara Fault. The presence of the fault helps to better understand the shape of the potentiometric surface. These data will be used to better understand the hydrologic parameters controlling the containment of the waste at US Ecology. Quaternary geologic units exposed at the surface, in the vicinity of US Ecology, are derived from the alluvium shed off the adjacent range front and the Amargosa River. These deposits vary from modern to early Pleistocene in age. At depth, heterogeneous sands and gravel occur. Observed in deep trenches and boreholes, the subsurface deposits are characterized as fining-upward sequence of sediment from 5- to 8-meters thick. No volcanic units or fine-grained playa deposits were described in the boreholes to a depth of 200 meters. Based on Infrared Stimulated Luminescence dated core samples, short-term rates of sediment accumulation (<70,000 years) are an average of 2.7 millimeters per year, however, long-term rates (<3,900,000 years) are orders of magnitude less. Resistivity data, when compared to lithologic cross sections, generally are consistent with lithology grain size and probable soil carbonate accumulations. Surface resistivity

  10. The regional structural setting of the 2008 Wells earthquake and Town Creek Flat Basin: implications for the Wells earthquake fault and adjacent structures

    USGS Publications Warehouse

    Henry, Christopher S.; Colgan, Joseph P.

    2011-01-01

    The 2008 Wells earthquake occurred on a northeast-striking, southeast-dipping fault that is clearly delineated by the aftershock swarm to a depth of 10-12 km below sea level. However, Cenozoic rocks and structures around Wells primarily record east-west extension along north- to north-northeast-striking, west-dipping normal faults that formed during the middle Miocene. These faults are responsible for the strong eastward tilt of most basins and ranges in the area, including the Town Creek Flat basin (the location of the earthquake) and the adjacent Snake Mountains and western Windermere Hills. These older west-dipping faults are locally overprinted by a younger generation of east-dipping, high-angle normal faults that formed as early as the late Miocene and have remained active into the Quaternary. The most prominent of these east-dipping faults is the set of en-échelon, north-striking faults that bounds the east sides of the Ruby Mountains, East Humboldt Range, and Clover Hill (about 5 km southwest of Wells). The northeastern-most of these faults, the Clover Hill fault, projects northward along strike toward the Snake Mountains and the approximately located surface projection of the Wells earthquake fault as defined by aftershock locations. The Clover Hill fault also projects toward a previously unrecognized, east-facing Quaternary fault scarp and line of springs that appear to mark a significant east-dipping normal fault along the western edge of Town Creek Flat. Both western and eastern projections may be northern continuations of the Clover Hill fault. The Wells earthquake occurred along this east-dipping fault system. Two possible alternatives to rupture of a northern continuation of the Clover Hill fault are that the earthquake fault (1) is antithetic to an active west-dipping fault or (2) reactivated a Mesozoic thrust fault that dips east as a result of tilting by the west-dipping faults along the west side of the Snake Mountains. Both alternatives are

  11. Origin of fluid inclusion water in bedded salt deposits, Palo Duro Basin, Texas

    SciTech Connect

    Knauth, L.P.; Beeunas, M.A.

    1985-07-01

    Salt horizons in the Palo Duro Basin being considered for repository sites contain fluid inclusions which may represent connate water retained in the salt from the time of original salt deposition and/or external waters which have somehow penetrated the salt. The exact origin of this water is important to the question of whether or not internal portions of the salt deposit have been, and are likely to be, isolated from the hydrosphere for long periods of time. The /sup 18/O//sup 16/O and D/H ratios measured for water extracted from solid salt samples show the inclusions to be dissimilar in isotopic composition to meteoric waters and to formation waters above and below the salt. The fluid inclusions cannot be purely external waters which have migrated into the salt. The isotope data are readily explained in terms of mixed meteoric-marine connate evaporite waters which date back to the time of deposition and early diagenesis of the salt (>250 million years). Any later penetration of the salt by meteoric waters has been insufficient to flush out the connate brines.

  12. Third-order Middle Miocene-Early Pliocene depositional sequences in the prograding delta complex of the Pannonian Basin

    USGS Publications Warehouse

    Vakarcs, G.; Vail, P.R.; Tari, G.; Pogácsás, Gy.; Mattick, R.E.; Szabo, A.

    1994-01-01

    Few studies exist in the geologic literature that show the distribution of seismic facies and depositional sequences within a lacustrine basin. The Pannonian Basin of Central Europe offers a unique opportunity to evaluate the influence of the eustatic signal on lacustrine deposition. Seismic stratigraphie and sedimentological studies indicate that the Middle Miocene-Early Pliocene infill of the transtensional Pannonian Basin was formed by large delta systems. Systematic sequence stratigraphie analysis of 6000 km of reflection seismic data and more than 100 hydrocarbon exploration wells in Hungary allowed the identification of twelve third-order sequence boundaries in the late Neogene sedimentary fill. This number of depositional sequences corresponds to that of the published global eustatic curve for this time period. Furthermore, based on magnetostratigraphic and radiometric data, the ages of these depositional sequences can be tentatively correlated with the global eustatic curve. The Pannonian Basin became isolated from the world sea at the Sarmatian/Pannonian (11.5 Ma) boundary and formed a large lake. The stratal patterns and sedimentary facies of individual systems tracts within the lacustrine sequences display the same characteristics as marine depositional sequences. The relatively low rate of thermal subsidence and the high rate of sediment supply resulted in a good sequence resolution. Within the third-order sequences higher-order sequences can be recognized with an average duration of about 0.1-0.5 Ma. ?? 1994.

  13. Application of the Basin Characterization Model to Estimate In-Place Recharge and Runoff Potential in the Basin and Range Carbonate-Rock Aquifer System, White Pine County, Nevada, and Adjacent Areas in Nevada and Utah

    USGS Publications Warehouse

    Flint, Alan L.; Flint, Lorraine E.

    2007-01-01

    A regional-scale water-balance model was used to estimate recharge and runoff potential and support U.S. Geological Survey efforts to develop a better understanding of water availability for the Basin and Range carbonate-rock aquifer system (BARCAS) study in White Pine County, Nevada, and adjacent areas in Nevada and Utah. The water-balance model, or Basin Characterization Model (BCM), was used to estimate regional ground-water recharge for the 13 hydrographic areas in the study area. The BCM calculates recharge by using a distributed-parameter, water-balance method and monthly climatic boundary conditions. The BCM requires geographic information system coverages of soil, geology, and topographic information with monthly time-varying climatic conditions of air temperature and precipitation. Potential evapotranspiration, snow accumulation, and snowmelt are distributed spatially with process models. When combined with surface properties of soil-water storage and saturated hydraulic conductivity of bedrock and alluvium, the potential water available for in-place recharge and runoff is calculated using monthly time steps using a grid scale of 866 feet (270 meters). The BCM was used with monthly climatic inputs from 1970 to 2004, and results were averaged to provide an estimate of the average annual recharge for the BARCAS study area. The model estimates 526,000 acre-feet of potential in-place recharge and approximately 398,000 acre-feet of potential runoff. Assuming 15 percent of the runoff becomes recharge, the model estimates average annual ground-water recharge for the BARCAS area of about 586,000 acre-feet. When precipitation is extrapolated to the long-term climatic record (1895-2006), average annual recharge is estimated to be 530,000 acre-feet, or about 9 percent less than the recharge estimated for 1970-2004.

  14. Depositional architecture of a mixed travertine-terrigenous system in a fault-controlled continental extensional basin (Messinian, Southern Tuscany, Central Italy)

    NASA Astrophysics Data System (ADS)

    Croci, Andrea; Della Porta, Giovanna; Capezzuoli, Enrico

    2016-03-01

    The extensional Neogene Albegna Basin (Southern Tuscany, Italy) includes several thermogene travertine units dating from the Miocene to Holocene time. During the late Miocene (Messinian), a continental fault-controlled basin (of nearly 500-km2 width) was filled by precipitated travertine and detrital terrigenous strata, characterized by a wedge-shaped geometry that thinned northward, with a maximum thickness of nearly 70 m. This mixed travertine-terrigenous succession was investigated in terms of lithofacies types, depositional environment and architecture and the variety of precipitated travertine fabrics. Deposited as beds with thickness ranging from centimetres to a few decimetres, carbonates include nine travertine facies types: F1) clotted peloidal micrite and microsparite boundstone, F2) raft rudstone/floatstone, F3) sub-rounded radial coated grain grainstone, F4) coated gas bubble boundstone, F5) crystalline dendrite cementstone, F6) laminated boundstone, F7) coated reed boundstone and rudstone, F8) peloidal skeletal grainstone and F9) calci-mudstone and microsparstone. Beds of terrigenous deposits with thickness varying from a decimetre to > 10 m include five lithofacies: F10) breccia, F11) conglomerate, F12) massive sandstone, F13) laminated sandstone and F14) claystone. The succession recorded the following three phases of evolution of the depositional setting: 1) At the base, a northward-thinning thermogene travertine terraced slope (Phase I, travertine slope lithofacies association, F1-F6) developed close to the extensional fault system, placed southward with respect to the travertine deposition. 2) In Phase II, the accumulation of travertines was interrupted by the deposition of colluvial fan deposits with a thickness of several metres (colluvial fan lithofacies association, F10 and F12), which consisted of massive breccias, adjacent to the alluvial plain lithofacies association (F11-F14) including massive claystone and sandstone and channelized

  15. Late quaternary depositional systems and sea level change-Santa Monica and San Pedro Basins, California continental borderland

    SciTech Connect

    Nardin, T.R.

    1983-07-01

    A suite of seismic reflection data that provides different degrees of resolution and penetration was used to map the depositional systems that have developed in Santa Monica and San Pedro basins during the late Quaternary. Submarine fan growth, particularly at the mouths of Hueneme and Redondo Canyons, has been the dominant mode of basin filling. Mass movement processes, ranging from creep to large-scale catastrophic slumping, have been important locally. In general, large-scale fan growth fits Normark's model in which the suprafan is the primary locus of coarse sediment deposition. Smaller scale morphologic and depositional patterns on the Hueneme and Redondo fans (e.g., distributary channels and coarse sediment concentrations basinward of the inner suprafan) suggest that a significant amount of coarse sediment presently bypasses the suprafans, however. Long-distance coarse sediment transport was particularly pronounced during late Wisconsinan lowstand of sea level and resulted in progradation of lower mid-fan and lower fan deposits.

  16. Sr-Nd isotopes constrain on the deposit history of the basins in the Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Li, Y.; Jiang, S.

    2015-12-01

    The Brazos-Trinity Basin IV and Ursa Basin are situated on the northern slope of the Gulf of Mexico. The Ursa basin lies in the center of late Pleistocene Mississippi River deposition, received the sediment deposition during Marine Isotope Stage (MIS) 2- 4. The Brazos-Trinity Basin IV belongs to a part of the Brazos-Trinity fan, it recorded the turbidite deposition and hemiplegic deposition during MIS1- 5. The Sr and Nd isotopic composition of the detrital composition of the sediment in both basins indicates the change of the sediment provenance during the basin-filled process. In the Ursa basin, The difference of 87Sr/86Sr ratio and ɛNd of the detrital component between MIS1,2 (87Sr/86Sr ~ 0.7219 - 0.7321, ɛNd ~ -12 - -13.4) and MIS3,4(87Sr/86Sr ~ 0.7310 - 0.7354, ɛNd ~ -16 - -17.9) is suggested to be related with the provenance change of the detrital particles since LGM. The addition of detrital particle from Appalachians with less radiogenic 87Sr/86Sr and positive ɛNd altered the character of the sediment of the Mississippi River during the last glaciation and deglaciation. In the Brazos-Trinity Basin IV, the narrow range of 87Sr/86Sr and ɛNd indicate that the sediment source of Brazos-Trinity Basin IV had not changed obviously during MIS5e to MIS2, mostly from coastal rivers such as Brazos River, Trinity River and Sabine River. The pre-fan with 87Sr/86Sr ~0.735 and ɛNd ~ -14.5 to -16.9, which is very similar to the deep sediment in the Ursa Basin with 87Sr/86Sr ~0.733 to 0.735 and ɛNd ~ -16 to -18. It is suggested that sediments of the pre-fan of the Brazos-Trinity Basin IV were supplied from the ancestral Mississippi River Delta during the low sea level (MIS 6). During the MIS5, the discharge of Mississippi River is thought switched to its present course, ~300 km to the east.

  17. Calcium chloride brines: The vital component in the hydrothermal brine-hydrothermal ore deposit-evaporite-basinal brine cycle in continental rift basins

    SciTech Connect

    Hardie, L. . Dept. of Earth and Planetary Science)

    1992-01-01

    Nonmarine evaporites are forming today in chloride-rich saline lakes in a number of arid continental rift and strike-slip basins that are characterized by upwelling of subsurface CaCl[sub 2]-bearing brines driven by forced convection of cool basinal brines or by free convection of hydrothermal brines which reach the surface as brine springs. The compositions of these upwelling brines are distinctively different from that of seawater or typical continental waters due primarily to their high proportion of Ca and low proportion of SO[sub 4]. The most viable explanation for the CaCl[sub 2] composition of these upwelling brines is the interaction between hot convecting groundwaters and bedrock at or above zeolite facies temperatures, as for example occurs in the modern Salton Sea basin. Such upwelling CaCl[sub 2] brines in extensional fault basins can explain the puzzling chemical composition of MgSO[sub 4]-poor potash evaporites, the least understood of all ancient salt deposits. In this regard it is suggested that the following cyclic succession of processes occurs in active continental rift basins during a magmatically-driven thermal event: (1) hydrothermal convection of the ambient porewaters in the rift sediments, (2) dissolution of buried evaporites and hydrothermal metamorphism of the rift sediments, (3) hydrothermal ore deposition in fault-related fractures and within the rift sediments, (4) upwelling brine springs add CaCl[sub 2] and KCl components to the surface lake waters, which on evaporation produce MgSO[sub 4]-poor potash evaporites, (5) decay of the thermal event leads to cool down of the hot brines, which now migrate gravitationally to the deeper parts of the basin to become static Na-Ca-Cl basinal brines.

  18. Depositional and diagenetic history and petroleum geology of the Jurassic Norphlet Formation of the Alabama coastal waters area and adjacent federal waters area

    USGS Publications Warehouse

    Kugler, R.L.; Mink, R.M.

    1999-01-01

    The discovery of deep (>20,000 ft) gas reservoirs in eolian sandstone of the Upper Jurassic Norphlet Formation in Mobile Bay and offshore Alabama in the late 1970s represents one of the most significant hydrocarbon discoveries in the nation during the past several decades. Estimated original proved gas from Norphlet reservoirs in the Alabama coastal waters and adjacent federal waters is 7.462 trillion ft3 (Tcf) (75% recovery factor). Fifteen fields have been established in the offshore Alabama area. Norphlet sediment was deposited in an arid environment in alluvial fans, alluvial plains, and wadis in updip areas. In downdip areas, the Norphlet was deposited in a broad desert plain, with erg development in some areas. Marine transgression, near the end of Norphlet deposition, resulted in reworking of the upper part of the Norphlet Formation. Norphlet reservoir sandstone is arkose and subarkose, consisting of a simple assemblage of three minerals, quartz, albite, and K-feldspar. The present framework grain assemblage of the Norphlet is dominantly diagenetic, owing to albitization and dissolution of feldspar. Despite the simple framework composition, the diagenetic character of the Norphlet is complex. Important authigenic minerals include carbonate phases (calcite, dolomite, Fe-dolomite, and breunnerite), feldspar (albite and K-feldspar), evaporite minerals (anhydrite and halite), clay minerals (illite and chlorite), quartz, and pyrobitumen. The abundance and distribution of these minerals varies significantly between onshore and offshore regions of Norphlet production. The lack of sufficient internal sources of components for authigenic minerals, combined with unusual chemical compositions of chloride (Mg-rich), breunnerite, and some minor authigenic minerals, suggests that Louann-derived fluids influenced Norphlet diagenesis. In offshore Alabama reservoirs, porosity is dominantly modified primary porosity. Preservation of porosity in deep Norphlet reservoirs is due

  19. Alluvial fan deposition along a rift depocentre border from the Neuquén Basin, Argentina

    NASA Astrophysics Data System (ADS)

    Muravchik, Martin; Bilmes, Andrés; D'Elia, Leandro; Franzese, Juan R.

    2014-03-01

    The interaction between hangingwall block rotation and alluvial deposition is examined from Late Triassic-Early Jurassic successions exposed along the Catán Lil half-graben border fault system in the Neuquén Basin, Argentina. Analysis of transport and depositional processes, clast composition and rock body geometry allowed the identification of three distinctive fan-shaped alluvial units. The contrasting lithologic nature of the basement (igneous-metamorphic) and syn-rift fill (volcanic and volcanic-derived) permits detailed studies of clast provenance. The origin of each alluvial system (footwall- vs. hangingwall-derived) can thus be verified. A simple method was implemented to establish the geometry of each alluvial unit by comparing the stereographic projection of its bedding to that of an idealised fan shaped body. Results show that the three alluvial systems occupied the same relative location in the rift depocentre. Unit 1 is interpreted as an alluvial fan orientated transverse to the depocentre border fault system and fed from the footwall. Non-cohesive debris flow deposition was the dominant process in this environment. Unit 2 is interpreted as a mainly hangingwall-fed alluvial fan, parallel to the depocentre border fault system and shows an upward decrease in footwall-derived clasts. Hyperconcentrated flow was the principal transport process. Unit 3 represents a fan delta, parallel to the depocentre border fault system. Its components are completely hangingwall-derived and hyperconcentrated flow deposition was the dominant process. Differences in grain-size, composition, transport directions and fan body geometry are proved to be directly linked to variations in ground tilting induced by the direction of hangingwall block rotation in an endorheic rift depocentre.

  20. Stratigraphy, depositional history and environments of deposition of Cretaceous through Tertiary strata in the Lamu Basin, southeast Kenya and implications for reservoirs for hydrocarbon exploration

    NASA Astrophysics Data System (ADS)

    Nyagah, Kivuti

    1995-04-01

    The Lamu Basin, which is characterized by an extensional tectonic style, is the failed arm of a tri-radial rift system and possesses tectonic and stratigraphic elements in the post-rift series that are analogous to those of the west coast of Africa. Development of the southern part of the basin as a passive margin, is closely related to considerations of the pre-drift position of Madagascar and formation of the Indian Ocean basin during Mesozoic time. Cretaceous and Tertiary strata in the basin comprise an eastward-thickening gross succession of sediments on which eustatic sea-level fluctuations and a sequence of unconformities related to pulses of transgressive and regressive depositional trends, are superimposed. Recognition of these trends has provided the basis for classification of the strata into megasequences representing distinct provinces with regard to time stratigraphy, sedimentation, tectonics, depositional environments and hydrocarbon potential. Megasequence I (Karoo Group and Jurassic) includes strata of the Permian through Jurassic, the discussion of which is beyond the scope of this paper. Megasequence II (Sabaki Group) includes strata of the Cretaceous and Early Paleocene, deposited in tide-influenced shelf and marine settings. These are, in ascending order: the Ewaso Sands, the Walu Shale, the Hagarso Limestone, the Freretown Limestone and the Kofia Sands. Megasequence III (Tana Group) includes strata of the Eocene through Oligocene, which were deposited in fluvial, deltaic, and restricted-shelf settings. These are, in ascending order: the Kipini Formation, the Pate Limestone, the Linderina Limestone, the Dodori Limestone and the Barren Beds Formation. Megasequence IV (Coastal Group) includes strata of the Miocene through Pliocene, which were deposited in restricted-shelf, middle- to outer-shelf, deep-marine and fluvial settings. These are, in ascending order: the Baratumu Formation, the Lamu Reefs, the Simba Shales and the Marafa Formation

  1. The tail of the Storegga Slide: Insights from the geochemistry and sedimentology of the Norwegian Basin deposits

    USGS Publications Warehouse

    Paull, C.K.; Ussler, W.; Holbrook, W.S.; Hill, T.M.; Haflidason, H.; Winters, W.; Lorenson, T.; Aiello, I.; Johnson, J.E.; Lundsten, E.

    2010-01-01

    Deposits within the floor of the Norwegian Basin were sampled to characterize the deposition from the Storegga Slide, the largest known Holocene-aged continental margin slope failure complex. A 29 to 67 cm thick veneer of variable-coloured, finely layered Holocene sediment caps a homogeneous, extremely well-sorted, poorly consolidated, very fine-grained, grey-coloured sediment section that is >20 m thick on the basin floor. This homogeneous unit is interpreted to represent the uppermost deposits generated by a gravity flow associated with the last major Storegga Slide event. Sediments analogous to the inferred source material of the slide deposits were collected from upslope on the Norwegian Margin. Sediments sampled within the basin are distinguishable from the purported source sediments, suggesting that size sorting has significantly altered this material along its flow path. Moreover, the very fine grain size (3·1 ± 0·3 μm) suggests that the >20 m thick homogeneous unit which was sampled settled from suspension after the turbulent flow was over. Although the turbulent phase of the gravity flow that moved material out into the basin may have been brief (days), significantly more time (years) is required for turbid sediments to settle and dewater and for the new sea floor to be colonized with a normal benthonic fauna. Pore water sulphate concentrations within the uppermost 20 m of the event deposit are higher than those normally found in sea water. Apparently the impact of microbial sulphate reduction over the last ca 8·1 cal ka bp since the re-deposition of these sediments has not been adequate to regenerate a typical sulphate gradient of decreasing concentration with sub-bottom depth. This observation suggests low rates of microbial reactions, which may be attributed to the refractory carbon composition in these re-deposited sediments.

  2. 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

  3. Depositional model, dolomitization, and porosity of Henryhouse Formation (Silurian), Anadarko basin, Oklahoma

    SciTech Connect

    Beardall, G.B.

    1987-08-01

    The Upper Silurian Henryhouse Formation, which is part of the Hunton Group, is a major hydrocarbon reservoir in the Anadarko basin. Three basic lithofacies are present in the Henryhouse, based on sedimentary structures, lithology, fossil content, and fabric relationships. These facies, represented in general by massive lime mudstone with diverse fauna, burrowed dolowackestone/packstone with mainly crinoids, and massive to laminated dolomudstone with fenestral fabrics and sparse fauna, are inferred to represent subtidal, intertidal, and supratidal environments, respectively. These facies comprise a vertical sequence that represents regressive deposition. The Henryhouse consists of several of these sequences. The Henryhouse commonly is partly or completely dolomitized in western Oklahoma. Three stages of dolomitization were documented: (1) penecontemporaneous hypersaline dolomite occurring as brownish, hypidiotopic rhombs concentrated in the supratidal and intertidal facies, (2) mixed marine and freshwater dolomite occurring as white rims around preexisting hypersaline dolomite, and as subhedral, white rhombs in vugs and molds, and (3) deep-burial vug, mold, and fracture-filling saddle dolomite. Production in the Henryhouse is generally from porous zones in dolomite. However, lithofacies reflecting depositional environments in which they were formed are equally important in porosity development.

  4. Distribution of trace elements in drilling chip samples around a roll-type uranium deposit, San Juan Basin, New Mexico

    USGS Publications Warehouse

    Day, H.C.; Spirakis, C.S.; Zech, R.S.; Kirk, A.R.

    1983-01-01

    Chip samples from rotary drilling in the vicinity of a roll-type uranium deposit in the southwestern San Juan Basin were split into a whole-washed fraction, a clay fraction, and a heavy mineral concentrate fraction. Analyses of these fractions determined that cutting samples could be used to identify geochemical halos associated with this ore deposit. In addition to showing a distribution of selenium, uranium, vanadium, and molybdenum similar to that described by Harshman (1974) in uranium roll-type deposits in Wyoming, South Dakota, and Texas, the chemical data indicate a previously unrecognized zinc anomaly in the clay fraction downdip of the uranium ore.

  5. Basin geodynamics and sequence stratigraphy of Upper Triassic to Lower Jurassic deposits of Southern Tunisia

    NASA Astrophysics Data System (ADS)

    Carpentier, Cédric; Hadouth, Suhail; Bouaziz, Samir; Lathuilière, Bernard; Rubino, Jean-Loup

    2016-05-01

    Aims of this paper are to propose a geodynamic and sequential framework for the late Triassic and early Jurassic of and south Tunisia and to evidence the impact of local tectonics on the stratigraphic architecture. Facies of the Upper Triassic to Lower Jurassic of Southern Tunisia have been interpreted in terms of depositional environments. A sequential framework and correlation schemes are proposed for outcrops and subsurface transects. Nineteen middle frequency sequences inserted in three and a half low frequency transgression/regression cycles were evidenced. Despite some datation uncertainties and the unknown durations of Lower Jurassic cycles, middle frequency sequences appear to be controlled by eustasy. In contrast the tectonics acted as an important control on low frequency cycles. The Carnian flooding was certainly favored by the last stages of a rifting episode which started during the Permian. The regression accompanied by the formation of stacked angular unconformities and the deposition of lowstand deposits during the late Carnian and Norian occured during the uplift and tilting of the northern basin margins. The transpressional activity of the Jeffara fault system generated the uplift of the Tebaga of Medenine high from the late Carnian and led to the Rhaetian regional angular Sidi Stout Unconformity. Facies analysis and well-log correlations permitted to evidence that Rhaetian to Lower Jurassic Messaoudi dolomites correspond to brecciated dolomites present on the Sidi Stout unconformity in the North Dahar area. The Early-cimmerian compressional event is a possible origin for the global uplift of the northern African margin and Western Europe during the late Carnian and the Norian. During the Rhaetian and the early Jurassic a new episode of normal faulting occured during the third low frequency flooding. This tectonosedimentary evolution ranges within the general geodynamic framework of the north Gondwana margin controlled by the opening of both

  6. Depositional architecture of Springer Old Woman sandstone, central Anadarko basin, Oklahoma

    SciTech Connect

    O'Donnell, M.R.; Haiduk, J.P.

    1987-08-01

    The fluvial meander belt containing the Old Woman sandstone served as a conduit for clastics transported into the Anadarko basin. Mappable for a distance of more than 30 mi (48 km), sand bodies characterizing this system average 0.5 mi (0.8 km) in width and attain maximum thicknesses of 50-70 ft (15-20 m). Channel and point-bar sandstone facies display a fining-upward sequence and sharp basal contact, as inferred from gamma-ray and resistivity logs. Sandstones of the Old Woman fluvial complex overlie the laminated shales and silts of the penecontemporaneous flood-plain environment. These flood-plain deposits are underlain by crinoidal wackestones and packstones deposited in the subtidal regime. Encroachment of the fluvial complex into a marine setting is interpreted from this sequence. Thin flood-plain deposits and lack of shallow marine clastic sediments suggest rapid advancement. Quartzitic and petrologically mature, the Old Woman sandstone is fine grained, with small-scale troughs and laminations, and a few mudstone rip-up clasts. Diagenesis has altered the mineralogic composition mainly by siliceous and carbonate cementation. Porosity is secondary, resulting from dissolution of various metastable constituents. The Old Woman sandstone was established as a hydrocarbon reservoir in the early 1960s, and sporadic development continued for years. The present-day petroleum market has prompted a resurgence in drilling activity owing to the economic viability of this reservoir. Successful wells are concentrated in newly discovered meander-belt bends; however, the elusiveness of this fluvial system challenges today's exploration geologists as it has for the past quarter century.

  7. Lithofacies distribution in Smackover/Haynesville (Oxfordian) depositional sequence, MAFLA Area, northeastern Gulf Coast Basin, U. S. A

    SciTech Connect

    Boronow, T.C. ); Prather, B.E. )

    1990-05-01

    Correlation of a basal carbonate unit a downlap or maximum flooding surface, and approximated time lines in a prograding unit provide the time-stratigraphic framework for mapping the distribution of reservoir, seal, and source lithofacies within the Smackover/Haynesville depositional sequence. Seismic sequence analysis of offshore data core control, onshore to offshore regional stratigraphic sections, and time-slice lithofacies maps show this depositional sequence to consist of a deepening-upward transgressive system tract (TST) and a shallowing-upward highstand systems tract (HST). The TST is composed of predominantly lime mudstones and microlaminated mudstones. These mudstones are source rocks for Norphlet and Smackover accumulations and top seals for some Norphlet accumulations. Reservoir rocks in the TST were deposited in high-energy environments localized over paleotopographic highs and around basin margins. The HST over most of offshore MAFLA is dominated by siliciclastic deposition. In these areas, the HST is characterized by sigmoid clinoform seismic character. The clinoforms result from interbedded carbonates. Source rocks occur in bottomsets and foresets, and grainstones are located in the topsets of these carbonate interbeds. The source rocks are part of a condensed zone deposited in a starved basin and grainstones were deposited at the paleostrandline. Sandstone reservoirs deposited by turbidity currents are found in bottomsets and shoreface sandstones occur in topsets of siliciclastic beds. The HST in onshore and offshore areas not affected by siliciclastic influx consists of shoaling-upward carbonate to evaporite parasequence sets. Here, grainstone reservoirs are capped by Buckner anhydrite top seals.

  8. Top of head scarp and internal scarps for landslide deposits in the Little North Santiam River Basin, Oregon

    USGS Publications Warehouse

    Sobieszczyk, Steven

    2010-01-01

    Data points represent head scarps, flank scarps, and minor internal scarps (linear) associated with landslide deposits in the Little North Santiam River Basin, Oregon. This work was completed as part of the Master's thesis "Turbidity Monitoring and LiDAR Imagery Indicate Landslides are Primary Source of Suspended-Sediment Load in the Little North Santiam River Basin, Oregon, Winter 2009-2010" by Steven Sobieszczyk, Portland State University and U.S. Geological Survey. Data layers in this geodatabase include: landslide deposit boundaries (Deposits); field-verfied location imagery (Photos); head scarp or scarp flanks (Scarp_Flanks); and secondary scarp features (Scarps).The geodatabase template was developed by the Oregon Department of Geology and Mineral Industries (Burns and Madin, 2009).

  9. Hellas Planitia, Mars - Site of net dust erosion and implications for the nature of basin floor deposits

    NASA Technical Reports Server (NTRS)

    Moore, Jeffrey M.; Edgett, Kenneth S.

    1993-01-01

    Hellas Planitia, located within an enclosed basin which includes the lowest topography on Mars, appears to be undergoing net erosion. Dust is removed from the basin. It probably contributes to global dust storms and should leave behind a coarse lag. The particle size distributions and particularly the rock or boulder populations in this lag might be useful for distinguishing between processes which formed the lithologic units that comprise Hellas Planitia. This report concludes that the abundance of rock particles larger than coarse sand is very low. Although this hypothesis awaits confirmation from forthcoming spacecraft data, the origins for Hellas floor deposits favored by this study are indurated volcanic airfall or ancient loess, lacustrine deposits, and some types of volcanic mud flows. The conclusions of this study tend to disfavor such geologic processes as blocky lava flows, glacial deposits (e,g., moraines), or boulder-laden catastrophic flood outwash.

  10. Sedimentology and stratigraphy of Cenozoic deposits in the Kağızman-Tuzluca Basin, northeastern Turkey

    NASA Astrophysics Data System (ADS)

    Varol, Baki; Şen, Şevket; Ayyıldız, Turhan; Sözeri, Koray; Karakaş, Zehra; Métais, Grégoire

    2016-01-01

    The Kağızman-Tuzluca Basin is located in the northeastern Anatolia, to the east of the intersection point (near Karlıova) of the major North and East Anatolian Fault systems. This intermontane basin displays a thick sequence (over 2000 m) of mostly terrestrial deposits represented by repetitive alternations of the lake and fluvial environments ranging from ?Late Eocene/Oligocene to Middle/? Late Miocene. A marine incursion only mappable in the southeastern margin of the basin deposited limestones and sandy limestones rich in marine mollusks and nummulites, in particular N. fichteli that constrain an Early Oligocene age for this marine unit (Kağan Fm). The terrestrial basin-fill deposits show different thicknesses throughout the basin due to irregular bottom topography and tectonic configuration of the basin margins. The thickest deposits were accumulated along the different margins of the basin, which received high quantities of siliciclastics from meandering river, alluvial and coastal fans, fan delta/Gilbert-type delta and wave-worked fluvial delta. Climate changes have also driven the development of lake environments during distinct depositional periods. Siliciclastic-dominated overfilled lakes (Halıkışlak and Kızılkaya formations) and chemical-dominated underfilled lakes (Turabi and Tuzluca formations) were formed. They have been also classified as "Newark-type" and "Fundy-type" lakes, respectively. Fluvial systems evolved from high-energy meandering rivers deposited under humid climate (Güngören Formation) to low-energy meandering rivers resulted from arid and semiarid climates (Çincavat Formation). The transitional intervals from ephemeral river-dry mudflat (Çincavat Formation) to saline pan/lake (Tuzluca Formation) indicate wadi-sand flat-playa fluvial systems. The chronostratigraphic constrains of the entire sequence remain poor and so far solely based on vertebrate fossil assemblages. The evaporitic Tuzluca Formation would be Middle Miocene in

  11. Local climate differences between the adjacent Linxia and Xunhua basins, NE Tibet reveal 11 Ma history of relief in the intervening Jishi Shan

    NASA Astrophysics Data System (ADS)

    Hough, B.; Garzione, C.; Wang, Z.; Zheng, W.; Yuan, D.; Zhang, P.; Molnar, P.

    2008-12-01

    The 3500-4000 m high Jishi Shan located on the boarder between Gansu and Qinghai Provinces along the northeast margin of the Tibetan Plateau stands as an orographic barrier to easterly derived summer rainfall. Comparison of stable isotope compositions of modern rainfall (δ18O and δ2H) and paleo-soil carbonate (δ18O and δ13C) from the leeward Xunhua basin and the windward Linxia basin provides a method for the interpretation of changes in local climate related to the formation of relief in the intervening Jishi Shan. Rayleigh distillation models suggest that a vapor mass experiencing orographic rainout should be relatively depleted in 18O on the lee side of the range. However, increased aridity in the rain shadow of the Jishi Shan results in a net 2‰ enrichment in the δ18O values of modern rainfall in the Xunhua basin due to evaporative enrichment of 18O. Using the stable isotope compositions of pedogenic and lacustrine carbonates in the Xunhua and Linxia basins as a proxy for paleoclimate, we find that the aridity difference between these basins has existed throughout at least the past 11 Ma, implying the presence of the Jishi Shan. These data indicate that intra- basin comparisons of the stable isotope composition of sedimentary carbonates can be used to assess the timing of emergence of basin-segmenting mountain ranges between the sub-basins of northeastern Tibet.

  12. 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

  13. Subsurface lacustrine storm-seiche depositional model in the Eocene Lijin Sag of the Bohai Bay Basin, East China

    NASA Astrophysics Data System (ADS)

    Wang, Junhui; Jiang, Zaixing; Zhang, Yuanfu

    2015-10-01

    Recent progress in facies analysis helps to discriminate storm-induced deposits based on interpretation of sedimentary records of combination of oscillatory and unidirectional flows. Located in the southeastern corner of the Bohai Bay Basin in East China, the Lijin Sag is a NE-SW trending Cenozoic half-graben basin. Part of its Eocene deposits (Bindong deposits), which are deposited far away from a contemporary shoreline, consists of thin bedded fine-sandstones and siltstones, interlayed with dark-gray mudstones. New data from drilling wells permit an interpretation of the sedimentary facies. Based on seismic data, well log data, core data and thin-section analyses, storm-dominated deposits were recognized. Petrologic analysis shows that these deposits mainly consist of fine sand- to silt-sized lithic arkose. Detailed sedimentological analyses on lithofacies were conducted to address flowtypes dominant during their geneses. The beds are normal graded and contain Bouma-like sequences. The typical and complete sedimentary sequence consists of fining-upwards successions from an erosive base, followed by gravity flow-induced massive or faint laminated bed or soft sediment deformation structures and unidirectional-combined-oscillatory flow induced beddings, which are attributed to storm wave and seiche processes. From proximal to distal in plane, the Bindong storm deposits exhibit different lithofacies associations and sedimentary processes, i.e., the proximal facies is coarser and dominated by gravity flows, unidirectional flows and combined flows, and formed under strong hydrodynamic conditions; the transitional facies is formed under full range of flow regimes exhibiting a complete Bouma-like sequence; while the distal facies is dominated by gravity flows and pure unidirectional flows without influence of waves. During the deposition period of the Bindong deposits, the paleo-environmental characteristics, such as paleogeographic position, paleoclimate, provenance

  14. Seismic expression of depositional systems tracts and application to hydrocarbon exploration in Bredasdorp basin, offshore South Africa

    SciTech Connect

    Beamish, G.W.J.

    1989-03-01

    Postrift Cretaceous sequences of Bredasdorp basin, offshore South Africa, were rigorously analyzed using the unified application of the latest seismic-stratigraphic, sequence-stratigraphic, and depositional systems concepts. Using 101 seismic profiles totaling 5600 km, the authors identified ten cyclic depositional sequences bounded by nine type 1 and two type 2 unconformities. Component depositional systems tracts exhibit a distinct seismic expression and can be delineated using truncation and lap-out relationships. Lowstand systems tracts developed on type 1 unconformities, which resulted from relative sea level fall below the shelf edge. In a terrigenous clastic basin such as Bredasdorp, these tracts are interpreted as being composed of basin-floor turbidite fans, channels, and/or sheets. These features formed contemporaneously with the erosion of incised valleys and submarine canyons, followed by channelized slope fans and deltaic/coastal lowstand wedges that prograded during a relative sea level rise. Subsequent flooding of the shelf as relative sea level rise accelerated resulted in poorly defined transgressive systems tracts. With the relative sea level at a highstand, extensively developed deltaic/coastal systems prograded basinward exhibiting well-defined clinoforms. The major hydrocarbon plays in the lowstand tracts occur as mounded basin-floor turbidite fans, channel fills, and draped sheets and are found in the updip pinch-out of deltaic/coastal sandstones.

  15. Evaluating upper versus lower crustal extension through structural reconstructions and subsidence analysis of basins adjacent to the D'Entrecasteaux Islands, eastern Papua New Guinea

    NASA Astrophysics Data System (ADS)

    Fitz, Guy; Mann, Paul

    2013-06-01

    The D'Entrecasteaux Island (DEI) gneiss domes are fault-bounded domes with ~2.5 km of relief exposing ultrahigh-pressure (UHP) and high-pressure (HP) metamorphic gneisses and migmatites exhumed in an Oligocene-Miocene arc-continent collision and subduction zone subject to late Miocene to recent continental extension. Multichannel seismic reflection data and well data show the Trobriand basin formed as a fore-arc basin caused by southward Miocene subduction at the Trobriand trench. Subduction slowed at ~8 Ma as the margin transitioned to an extensional tectonic environment. Since then, the Trobriand basin has subsided 1-2.5 km as a broad sag basin with few normal faults deforming the basin fill. South of the DEI, the Goodenough rift basin developed after extension began (~8 Ma) as the hanging wall of the north-dipping Owen-Stanley normal fault that bounds the basin's southern margin. The lack of upper crustal extension accompanying subsidence in the Trobriand and Goodenough basins suggests depth-dependent lithospheric extension since 8 Ma has accompanied uplift of the DEI gneiss domes. Structural reconstructions of seismic profiles show 2.3-13.4 km of basin extension in the upper crust, while syn-rift basin subsidence values indicate at least 20.7-23.6 km of extension occurred in the entire crust since ~8 Ma. Results indicating thinning is preferentially accommodated in the lower crust surrounding the DEI are used to constrain a schematic model of uplift of the DEI domes involving vertical exhumation of buoyant, postorogenic lower crust, far-field extension from slab rollback, and an inverted two-layer crustal density structure.

  16. The fabric of Mass Transport Deposits in the Ursa Basin, Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Day-Stirrat, R. J.; Flemings, P. B.; Strong, H. E.; Schneider, J.; Sawyer, D. E.; Schleicher, A. M.; Germaine, J. T.

    2009-12-01

    Mass Transport Deposits (MTDs) in the Ursa Basin, Gulf of Mexico, are densified relative to surrounding, undeformed, sediments. MTDs form a large fraction of the stratigraphic record. Their properties control basin fluid flow, impact seismic imaging, and are important for the development of subsea infrastructure. MTD-2 is one outstanding ~50m thick example where at a depth of 104.5mbsf, the porosity is 35%, while the immediate undeformed sediment below has a porosity of 47%. We analyzed the fabric of sediment within and outside, both above and below, of the MTD’s at Ursa. High-resolution x-ray texture goniometry (HRXTG) quantifies the alignment of clay minerals and shows greater basal plane alignment of smectite and illite within the MTDs relative to sediment outside the MTDs. A non-MTD sample immediately below MTD-2 has a weak fabric (m.r.d. = 2.5) whereas samples within the MTD have moderate fabrics (m.r.d. = 3-3.5). Pore throat analysis illustrates that the increase in alignment and the decrease in porosity is associated with a shift in mode pore throat size from 121 to 52 nanometers in the MTD vs. outside of the MTD. SEM images on ion-milled surfaces confirm that large pore throats are lost within the MTD. We interpret that the densification within MTDs is due to sediment remolding during debris flow. Remolding reorients the original clay mineral fabric, resulting in grains that have closer packing, lower porosity, and greater alignment than non-remolded sediments at the same effective stress.

  17. Late quaternary deposition in the inner basins of the California continental borderland - Part A. Santa Monica Basin

    USGS Publications Warehouse

    Normark, William R.; McGann, Mary

    2004-01-01

    Radiocarbon dating of sediment core samples from Santa Monica Basin document Holocene (younger than approximately 11 ka) landslides and fault offsets along the basin margin. The new dates include 17 from six piston cores on the continental slope and 11 from Ocean Drilling Program Site 1015 on the basin floor. The dates, which are based on data from pelagic and benthic foraminifera in addition to several dates from mollusk shells, are used to provide chronostratigraphic control for a previously determined basin-wide seismic stratigraphy. The geologic setting at the core sites and a sediment log for each core are shown. In addition, each sediment log is accompanied by a color core photograph as well as P-wave velocity and gamma-ray density profiles. The primary purpose of the report is to make the radiocarbon dates available for other studies in the Santa Monica Basin. A comparison of sediment accumulation rates between the late Pleistocene and Holocene provides insight to the effects of sea-level change on sediment input to the basin. In addition, the results can be used to evaluate the effectiveness of wire-line piston coring in providing age control for earthquake hazard and sedimentologic studies.

  18. Large landslides, composed of megabreccia, interbedded in Miocene basin deposits, southeastern Arizona

    USGS Publications Warehouse

    Krieger, Medora Louise Hooper

    1977-01-01

    The landslides in the Kearny and El Capitan Mountain quadrangles, Pinal and Gila Counties, Ariz., are tabular or lens like masses of megabreccia enclosed in Miocene basin deposits. The megabreccias within individual slide blocks are composed of pervasively brecciated Precambrian and younger formations that remain in normal stratigraphic sequence, indicating that each landslide moved as a fairly coherent mass. The megabreccias consist of fresh, mostly angular rock fragments in a comminuted matrix of the same composition as the fragments. The matrix ranges in amount from sparse to abundant. Where the matrix is sparse, the fragments fit tightly with little or no rotation. Locally fragments are rotated but not moved far; most units within a slide block are lithologically homogeneous. The Kearny landslides are conformably interbedded in steeply east-dipping playa and alluvial deposits. They form map units from a few tens of meters to nearly 4 km long and from less than 1 to 270 m wide. Narrow ridges expose sections through the landslides at about right angles to the direction of movement. The upper (proximal) ends have been eroded; the lower (distal) ends are buried. The El Capitan landslide dips very gently southward. Although partly dissected during erosion of the enclosing alluvial and lakebed deposits, its approximate original outline is still preserved. It forms a thin sheet, 5-15 m thick and at least 3.8 km long; the maximum outcrop width, near its distal end, is about 1.5 km. The Kearny landslides show little evidence of having exerted differential pressure on the underlying soft playa and alluvial deposits, and the contacts with the underlying sediments have little relief. The distal end of the El Capitan landslide, on the other hand, has considerable relief. As the landslide came to an abrupt stop, the end plowed into the underlying sediments, compressing them into fol9.s and forming sandstone dikes. The source of the El Capitan landslide is a well

  19. Estimation of hydrothermal deposits location from magnetization distribution and magnetic properties in the North Fiji Basin

    NASA Astrophysics Data System (ADS)

    Choi, S.; Kim, C.; Park, C.; Kim, H.

    2013-12-01

    The North Fiji Basin is belong to one of the youngest basins of back-arc basins in the southwest Pacific (from 12 Ma ago). We performed the marine magnetic and the bathymetry survey in the North Fiji Basin for finding the submarine hydrothermal deposits in April 2012. We acquired magnetic and bathymetry datasets by using Multi-Beam Echo Sounder EM120 (Kongsberg Co.) and Overhouser Proton Magnetometer SeaSPY (Marine Magnetics Co.). We conducted the data processing to obtain detailed seabed topography, magnetic anomaly, reduce to the pole(RTP), analytic signal and magnetization. The study areas composed of the two areas(KF-1(longitude : 173.5 ~ 173.7 and latitude : -16.2 ~ -16.5) and KF-3(longitude : 173.4 ~ 173.6 and latitude : -18.7 ~ -19.1)) in Central Spreading Ridge(CSR) and one area(KF-2(longitude : 173.7 ~ 174 and latitude : -16.8 ~ -17.2)) in Triple Junction(TJ). The seabed topography of KF-1 existed thin horst in two grabens that trends NW-SE direction. The magnetic properties of KF-1 showed high magnetic anomalies in center part and magnetic lineament structure of trending E-W direction. In the magnetization distribution of KF-1, the low magnetization zone matches well with a strong analytic signal in the northeastern part. KF-2 area has TJ. The seabed topography formed like Y-shape and showed a high feature in the center of TJ. The magnetic properties of KF-2 displayed high magnetic anomalies in N-S spreading ridge center and northwestern part. In the magnetization distribution of KF-2, the low magnetization zone matches well with a strong analytic signal in the northeastern part. The seabed topography of KF-3 presented a flat and high topography like dome structure at center axis and some seamounts scattered around the axis. The magnetic properties of KF-3 showed high magnetic anomalies in N-S spreading ridge center part. In the magnetization of KF-2, the low magnetization zone mismatches to strong analytic signal in this area. The difference of KF-3

  20. Lower and lower Middle Pennsylvanian fluvial to estuarine deposition, central Appalachian basin: Effects of eustasy, tectonics, and climate

    USGS Publications Warehouse

    Greb, S.F.; Chesnut, D.R.

    1996-01-01

    Interpretations of Pennsylvanian sedimentation and peat accumulation commonly use examples from the Appalachian basin because of the excellent outcrops and large reserve of coal (>100 billion metric tons) in the region. Particularly controversial is the origin of Lower and lower Middle Pennsylvanian quartzose sandstones; beach-barrier, marine-bar, tidalstrait, and fluvial models all have been applied to a series of sand bodies along the western outcrop margin of the basin. Inter-pretations of these sandstones and their inferred lateral relationships are critical for understanding the relative degree of eustatic, tectonic, and climatic controls on Early Pennsylvanian sedimentation. Cross sections utilizing >1000 subsurface records and detailed sedimentological analysis of the Livingston Conglomerate, Rockcastle Sandstone, Corbin Sandstone, and Pine Creek sandstone (an informal member) of the Breathitt Group were used to show that each of the principal quartzose sandstones on the margin of the central Appalachian basin contains both fluvial and marginal marine facies. The four sandstones are fluvially dominated and are inferred to represent successive bed-load trunk systems of the Appalachian foreland. Base-level rise and an associated decrease in extra-basinal sediment at the end of each fluvial episode led to the development of local estuaries and marine reworking of the tops of the sand belts. Each of the sand belts is capped locally by a coal, regardless of whether the upper surfaces of the sand belts are of fluvial or estuarine origin, suggesting allocyclic controls on deposition. Peats were controlled by a tropical ever-wet climate, which also influenced sandstone composition through weathering of stored sands in slowly aggrading braidplains. Recurrent stacking of thick, coarse-grained, fluvial deposits with extra-basinal quartz pebbles; dominance of bed-load fluvial-lowstand deposits over mixed-load, estuarine-transgressive deposits; thinning of sand belts

  1. 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

  2. A mid-Permian chert event: widespread deposition of biogenic siliceous sediments in coastal, island arc and oceanic basins

    USGS Publications Warehouse

    Murchey, B.L.; Jones, D.L.

    1992-01-01

    Radiolarian and conodont of Permian siliceous rocks from twenty-three areas in teh the circum-Pacific and Mediterranean regions reveal a widespread Permian Chert Event during the middle Leonardian to Wordian. Radiolarian- and (or) sponge spicule-rich siliceous sediments accumulated beneath high productivity zones in coastal, island arc and oceanic basins. Most of these deposits now crop out in fault-bounded accreted terranes. Biogenic siliceous sediments did not accumulate in terranes lying beneath infertile waters including the marine sequences in terranes of northern and central Alaska. The Permian Chert Event is coeval with major phosphorite deposition along the western margin of Pangea (Phosphoria Formation and related deposits). A well-known analogue for this event is middle Miocene deposition of biogenic siliceous sediments beneath high productivity zones in many parts of the Pacific and concurrent deposition of phosphatic as well as siliceous sediments in basins along the coast of California. Interrelated factors associated with both the Miocene and Permian depositional events include plate reorientations, small sea-level rises and cool polar waters. ?? 1992.

  3. Mineralogical and geochemical characteristics of the Noamundi-Koira basin iron ore deposits (India)

    NASA Astrophysics Data System (ADS)

    Mirza, Azimuddin; Alvi, Shabbar Habib; Ilbeyli, Nurdane

    2015-04-01

    India is one of the richest sources of iron ore deposits in the world; and one of them is located in the Noamundi-Koira basin, Singhbhum-Orissa craton. The geological comparative studies of banded iron formation (BIF) and associated iron ores of Noamundi-Koira iron ore deposits, belonging to the iron ore group in eastern India, focus on the study of mineralogy and major elemental compositions along with the geological evaluation of different iron ores. The basement of the Singhbhum-Orissa craton is metasedimentary rocks which can be traced in a broadly elliptical pattern of granitoids, surrounded by metasediments and metavolcanics of Greenstone Belt association. The Singhbhum granitoid is intrusive into these old rocks and to younger, mid Archaean metasediments, including iron formations, schists and metaquartzites and siliciclastics of the Precambrian Iron Ore Group (Saha et al., 1994; Sharma, 1994). The iron ore of Noamundi-Koira can be divided into seven categories (Van Schalkwyk and Beukes 1986). They are massive, hard laminated, soft laminated, martite-goethite, powdery blue dust and lateritic ore. Although it is more or less accepted that the parent rock of iron ore is banded hematite jasper (BHJ), the presence of disseminated martite in BHJ suggests that the magnetite of protore was converted to martite. In the study area, possible genesis of high-grade hematite ore could have occurred in two steps. In the first stage, shallow, meteoric fluids affect primary, unaltered BIF by simultaneously oxidizing magnetite to martite and replacing quartz with hydrous iron oxides. In the second stage of supergene processes, deep burial upgrades the hydrous iron oxides to microplaty hematite. Removal of silica from BIF and successive precipitation of iron resulted in the formation of martite- goethite ore. Soft laminated ores were formed where precipitation of iron was partial or absent. The leached out space remains with time and the interstitial space is generally filled

  4. Regional distribution of wave- and fluvial-dominated deltaic deposits of Olmos formation (upper Cretaceous) in Maverick basin, southwest Texas

    SciTech Connect

    Ambrose, W.; Tyler, N.

    1984-04-01

    Regional subsurface analysis in southwest Texas indicates that the Olmos Formation (Gulfian) was deposited by a complex of wave- and fluvial-dominated delta systems in two depocenters. Sediment influx was from the north and northwest. Five deltaic submits, A through E, were deposited in the western depocenter. Three other deltaic wedges (F, G, H) formed the second depocenter farther east in present-day Frio and LaSalle Counties. Subsidence was greater in the western half of the Maverick basin where thickest (1,300 ft; 395 m) deltaic sediments were deposited. Lower Olmos strata represent a succession from wave-reworked, strike-elongate deltas of subunit A, similar to those of the underlying San Miguel Formation, to fluvial-dominated, dip-elongate deltas of subunits B and C. Extensive (1200 mi/sup 2/ or 3100 km/sup 2/ in Texas) aggradational floodplain deposits of B and C are characterized by diverse electric-log patterns; variation in log character is a response to complex depositional facies on the delta platform. Downdip, toward the Cretaceous shelf edge, delta-plain facies merge with upward-coarsening delta-front sandstones. Uppermost subunits D and E were deposited by a prograding barrier-island system in an interdeltaic embayment marginal to high constructive deltas of the easter depocenter. Lagoonal and fluvial-channel deposits are recognized from cores. Eastward migration of deposition was accompanied by an abrupt change of depositional style in the western depocenter from deltaic to coastal-interdeltaic.

  5. Seismic Velocities and Thicknesses of Alluvial Deposits along Baker Creek in the Great Basin National Park, East-Central Nevada

    USGS Publications Warehouse

    Allander, Kip K.; Berger, David L.

    2009-01-01

    To better understand how proposed large-scale water withdrawals in Snake Valley may affect the water resources and hydrologic processes in the Great Basin National Park, the National Park Service needs to have a better understanding of the relations between streamflow and groundwater flow through alluvium and karst topography of the Pole Canyon Limestone. Information that is critical to understanding these relations is the thickness of alluvial deposits that overlay the Pole Canyon Limestone. In mid-April 2009, the U.S. Geological Survey and National Park Service used seismic refraction along three profiles adjacent to Baker Creek to further refine understanding of the local geology. Two refractors and three distinct velocity layers were detected along two of the profiles and a single refractor and two distinct velocity layers were detected along a third profile. In the unsaturated alluvium, average velocity was 2,000 feet per second, thickness ranged from about 7 to 20 feet along two profiles downstream of the Narrows, and thickness was at least 100 feet along a single profile upstream of the Narrows. Saturated alluvium was only present downstream of the Narrows - average velocity was 4,400 feet per second, and thickness ranged from about 40 to 110 feet. The third layer probably represented Pole Canyon Limestone or Tertiary granitic rock units with an average velocity of 12,500 feet per second. Along the upstream and middle profiles (profiles 3 and 1, respectively), the depth to top of the third layer ranged from at least 60 to 110 feet below land surface and is most likely the Pole Canyon Limestone. The third layer at the farthest downstream profile (profile 2) may be a Tertiary granitic rock unit. Baker Creek is disconnected from the groundwater system along the upstream profile (profile 3) and streamflow losses infiltrate vertically downward to the Pole Canyon Limestone. Along the downstream and middle profiles (profiles 2 and 1, respectively), the presence of

  6. 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.

  7. Tectonics, basin analysis and organic geochemical attributes of Permian through Mesozoic deposits and their derivative oils of the Turpan-Hami basin, northwestern China

    NASA Astrophysics Data System (ADS)

    Greene, Todd Jeremy

    The Turpan-Hami basin is a major physiographic and geologic feature of northwest China, yet considerable uncertainty exists as to the timing of its inception, its late Paleozoic and Mesozoic tectonic history, and the relationship of its petroleum systems to those of the nearby Junggar basin. Mesozoic sedimentary fades, regional unconformities, sediment dispersal patterns, and sediment compositions within the Turpan-Hami and southern Junggar basins suggest that these basins were initially separated between Early Triassic and Early Jurassic time. Prior to separation, Upper Permian profundal lacustrine and fan-delta fades and Triassic coarse-grained braided-fluvial/alluvial fades were deposited across a contiguous Junggar-Turpan-Hami basin. Permian through Triassic fades were derived mainly from the Tian Shan to the south as indicated by northward-directed paleocurrent directions and geochemical provenance of granitoid cobbles. Lower through Middle Jurassic strata begin to reflect ponded coal-forming, lake-plain environments within the Turpan-Hami basin. A sharp change in sedimentary-lithic-rich Lower Jurassic sandstone followed by a return to lithic volcanic-rich Middle Jurassic sandstone points to the initial uplift and unroofing of the largely andesitic Bogda Shan range, which first shed its sedimentary cover as it emerged to become the partition between the Turpan-Hami and southern Junggar basins. In Turpan-Hami, source rock age is one of three major statistically significant discriminators of effective source rocks in the basin. A newly developed biomarker parameter appears to track conifer evolution and can distinguish Permian rocks and their correlative oils from Jurassic coals and mudrocks, and their derivative oils. Source fades is a second key control on petroleum occurrence and character. By erecting rock-to-oil correlation models, the biomarker parameters separate oil families into end-member groups: Group 1 oils---Lower/Middle Jurassic peatland

  8. Deposition and watershed processing of mercury in the Lake Champlain basin

    SciTech Connect

    Scherbatskoy, T.; Rea, A.; Keeler, G.

    1995-12-31

    Daily wet-only precipitation, weekly 24-hour vapor and particulate matter, snowmelt and stream water have been analyzed for total mercury (Hg) in Underhill, VT since December, 1992. Total Hg in precipitation ranged from 1.2-35 ng/L, with maximum concentrations occurring during summer. Vapor phase Hg ranged from 1.2 to 4.2 ng/m, with little annual variability, and particulate phase Hg ranged from 1 to 43 pg/m{sup 3}, with maximum concentrations in winter. Wet-only deposition of total Hg in precipitation totaled 9.26 {mu}g/m{sup 2} in 1993 and 7.66 {mu}g/m{sup 2} in 1994. Total Hg concentrations in a stream in our research watershed were 1-3 ng/L during base flow, and reached 79 ng/L at peak flow during spring snowmelt. Dissolved Hg concentrations were approximately 2 ng/L, even during peak flows, suggesting suspended Hg-containing sediments caused the high total Hg during peak flows. Synoptic sampling of larger streams in the drainage basin also showed significant Hg enrichment during snowmelt. Limited snowpack melt measurements indicated that Hg concentration and dissolved proportion in melt water were dynamic, varying with temperature and melting rate.

  9. Provenance of the southern Junggar Basin in the Jurassic: Evidence from detrital zircon geochronology and depositional environments

    NASA Astrophysics Data System (ADS)

    Fang, Yanan; Wu, Chaodong; Guo, Zhaojie; Hou, Kejun; Dong, Lin; Wang, Luxin; Li, Linlin

    2015-01-01

    The goal of this paper is to study the provenance of the southern Junggar Basin during the late Triassic to early Cretaceous, based on the detrital U-Pb geochronology, petrography and depositional environments. Eight sandstone samples from the Upper Triassic to Lower Cretaceous were collected for detrital zircon U-Pb dating. A total of 794 effective U-Pb ages was obtained and divided into four groups: 488-2537 Ma (basement zircons), 328-482 Ma (subduction-related magmatic zircons), 254-322 Ma (post-collisional magmatic zircons), and 135-250 Ma (syndepositional magmatic zircons). These ages relate to three stages of basin evolution. (1) From the early to middle Jurassic, Tian Shan experienced continued exhumation, accompanied by progressive southward expansion of the Junggar Basin, and a peneplain was formed by the time Xishanyao Formation was deposited. Organic-rich sediments formed in a delta environment were well-developed in the southern Junggar Basin, with source rocks gradually switching from post-collisional volcanic rocks (295-307 Ma with a peak age of 300 Ma) of the southern North Tian Shan to post-collisional volcanic rocks of the Central Tian Shan (280-320 Ma with a peak age of 316 Ma) and then to subduction-related island arc rocks (402-423 Ma with a peak age of 415 Ma) of the Central Tian Shan. (2) During deposition of the Toutunhe and Qigu Formations, large scale volcanic activities occurred along the North Tian Shan Fault. Source rocks at this time include syndepositional volcanic rocks (151-161 Ma), and post-collisional volcanic rocks (290-320 Ma) of the North Tian Shan. By the time of deposition of the Kalazha Formation, Tian Shan experienced rapid tectonic uplift, leading to rapid lake regression. Alluvial fans were well developed in the southern Junggar Basin with source rocks being the underlying sedimentary strata of the north margin of the North Tian Shan. (3) During the early Cretaceous, exhumation of the Tian Shan and lake transgression in

  10. Estimation of mercury wet deposition in the tributary sub-basins of the Negro river (Amazon-Brazil) using RS/GIS tools

    NASA Astrophysics Data System (ADS)

    Jardim, W. F.; Silvério da Silva, G.

    2003-05-01

    Recent studies have shown high concentrations of Hg in fish, soil, lakes and rivers of the Negro river basin. These concentrations were surprisingly high when considering the scarcity of anthropogenic point sources in the region (Fadini and Jardim, 2001). In order to investigate the role of wet deposition in the mercury biogeochemistry cycle in this basin, Hg deposition was estimated for 18 tributary sub-basins of the Negro river, covering an area of nearly 700,000 km2. Mercury wet deposition estimate was done by combining analytical data obtained from total Hg measurements in bulk precipitation (8 measurements between 1997 and 2002), Remote Sensoring (RS) and GIS (Geographie Information System) tools, with the help of orbital images from the JERS-1 SAR project (Global Rain Forest Mapping Project, South America-Amazon Basin), Amazon rainfall map (Sombroek, 2001) and SPRING (Geographie information of processing system) from INPE (Brazilian National Institute of Space Research). For each sub-basin, Hg wet deposition flux (ton km^{-2} yr^{-1}) and the annual amount of Hg (ton yr^{-1}) deposited on the area were estimated. The result allowed a clear picture of each sub-basins, by looking for a relation between the wet deposition, the drainage characteristics of each sub-basin and the Hg concentration in the water column.

  11. Tectonic significance of large-scale chaotic deposits in a Cretaceous fore-arc basin: Valle Formation, Cedros Island (Mexico)

    SciTech Connect

    Smith, D.P.; Busby-Spera, C.J. )

    1990-05-01

    A mappable, deep-marine slide deposit (olistostrome) within medial-Cretaceous fore-arc basin strata (Valle Formation), located on Cedros Island, Baja California Norte, records the initiation of intrabasinal faulting. Studies of both modern and ancient olistostromes show that olistostromes can form in all physiographic provinces (including shelf and abyssal plain) and tectonic settings of the marine environment. A variety of triggering mechanisms have been suggested for olistostromes, including tectonism, sea level changes, diapirism, rapid sedimentation that overloads steep slopes, migration of gas hydrates, or combinations of the above. The olistostrome in the Valle Formation ranges in thickness from 0 to at least 180 m, and extends areally for at least 34 km{sup 2}. It can be divided into two parts. The basal 30-40 m contains large (up to 8 m) angular blocks (allolistoliths) derived from the Jurassic substrate. The allolistoliths decrease in abundance upsection, whereas internally coherent intraformational slide blocks (endolistoliths), which reach tens of meters in width, increase. Beds composing the endolistoliths are alternating mudstone and sandstone turbidites that were deposited on a tectonically stable basin plain or rise setting before catastrophic failure of the sedimentary pile produced the olistostrome. Intrabasinal faulting is invoked as a cause of the sediment failure because of the presence of allolistoliths, which must have been shed into the basin from uplifted( ) basin floor scarps. Allolistoliths occur sporadically throughout at least 400 m of coarse-clastic sediment gravity-flow deposits that cap the olistostrome, suggesting that intrabasinal faulting continued to affect the basin long after the olistrostrome formed.

  12. Dust deposits in Souss?Massa basin, South-West of Morocco: granulometrical, mineralogical and geochemical characterisation

    NASA Astrophysics Data System (ADS)

    Khiri, F.; Ezaidi, A.; Kabbachi, K.

    2004-08-01

    Samples of dust deposits were periodically collected from July 1, 1997 to January 30, 1999, at Souss-Massa basin, in the South of Morocco. Granulometrical, geochemical and mineralogical characterisations show that quartz, calcite and feldspars dominate the mineral contents of the dust deposit with a minor clay fraction. It indicates the mineralogical composition of dust collected in peri-Saharan regions. The material collected in the summer period is dominated by local dust against a mixture of local and proximal dusts in the winter period.

  13. Variations in trace element geochemistry in the Seine River Basin based on floodplain deposits and bed sediments

    USGS Publications Warehouse

    Horowitz, A.J.; Meybeck, Michel; Idlafkih, Z.; Biger, E.

    1999-01-01

    Between 1990 and 1995 a series of bed sediment, suspended sediment and fresh floodplain samples were collected within the Seine River Basin, in France, to evaluate variations in trace element geochemistry. Average background trace element levels for the basin were determined from the collection and subsequent analyses of bed sediment samples from small rural watersheds and from a prehistoric (5000 BP) site in Paris. Concentrations are relatively low, and similar to those observed for fine-grained bed sediments from unaffected areas in the United States and Canada. However, the concentrations are somewhat higher than the reference levels presently adopted by French water authorities for areas north of the Seine Basin, which have similar bedrock lithologies. Downstream trace element variations were monitored in 1994 and 1995 using fresh surficial floodplain samples that were collected either as dried deposits a few days after peak discharge, or immediately after peak discharge (under ??? 30 cm of water). Chemical comparisons between fresh floodplain deposits, and actual suspended sediments collected during flood events, indicate that, with some caveats, the former can be used as surrogates for the latter. The floodplain sediment chemical data indicate that within the Seine Basin, from the relatively unaffected headwaters through heavily affected urban streams, trace element concentrations vary by as much as three orders of magnitude. These trace element changes appear to be the result of both increases in population as well as concomitant increases in industrial activity. This article is a US government work and is in the public domain in the United States.

  14. Dating the Barremian-Aptian shallow platform deposits at the eastern part of the Kopet Dagh sedimentary basin, NE Iran

    NASA Astrophysics Data System (ADS)

    Chenarani, Atefeh; Hosseini, Seyedabolfazl; Vahidi Nia, Mohammad

    2016-04-01

    The Kopet Dagh sedimentary basin covers the northeastern part of Iran, most parts of Turkmenistan and north of Afghanistan which contains several giant gas fields. The extension of this basin in the Iranian part is around 55km2(Afshar Harb, 1994). The Kopet Dagh basin is marked by having very thick sedimentary rocks and lack of volcanic activity. During the Lower Cretaceous, the Tirgan Formation was deposited in a shallow platform setting and lithologically includes in thick-bedded orbitolinid limestones. This study focuses on the biostratigraphy and age determination of these shallow-water deposits using benthic foraminifera and calcareous green algae. In the studied outcrop, the Tirgan Formation has a thickness of 180 m and includes in limestone beds with some marly intervals. It is overlain by the Sarcheshmeh Formation and rests on the Shurijeh Formation. Both contacts are believed to be transitional and lack of discontinuity. A total of 56 thin-sections were used in this study. This study led to determine 28 genera and 14 species of benthic foraminifera along with 13 genera and 5 species of calcareous green algae. Based on the obtained biostratigraphy data, a late Barremian-early Aptian age is suggested for these deposits. We also defined the precise boundary between the Barremian and Aptian which is reported for the first time from this area. Keywords: Barremian-Aptian, Shallow platform, Kopet Dagh, Iran. Reference: Afshar Harb, A., 1994. Geology of Iran: Geology of the Kopet Dagh. Geological survey of Iran, Report No. 11, 275 pp.

  15. Mixed volcanogenic-lithogenic sources for Permian bauxite deposits in southwestern Youjiang Basin, South China, and their metallogenic significance

    NASA Astrophysics Data System (ADS)

    Yu, Wenchao; Algeo, Thomas J.; Du, Yuansheng; Zhang, Qilian; Liang, Yuping

    2016-07-01

    Bauxite deposits at the base of the Upper Permian Heshan Formation in the Youjiang Basin, South China, contain zircons with dominant age peaks at 263-262 Ma. During the Middle to Late Permian, the Youjiang Basin consisted of a number of isolated and attached carbonate platforms separated by inter-platform troughs. The bauxite deposits are limited to the isolated carbonate platform facies and are not present on attached carbonate platforms and inter-platform troughs. Discriminant plots based on the trace element composition of the zircons indicate a combination of within-plate/anorogenic and arc-related/orogenic sources. Geochemical and isotopic data suggest that the metallogenic materials of the bauxite deposit came from felsic volcanic rocks of the Emeishan Large Igneous Provence (ELIP) in South China and from the Truong Son volcanic arc located between the South China and Indochina cratons. The northwestern and southeastern parts of the Youjiang Basin received larger amounts of ELIP detritus and volcanic arc detritus, respectively. Coarser siliciclastic material in proximal attached carbonate platform and inter-platform trough settings was delivered by rivers, but finer siliciclastics that accumulated on distally located carbonate platforms in isolated deep-water areas was probably transported by wind.

  16. The influence of volcanism on fluvial depositional systems in a Cenozoic strike-slip basin, Denali fault system, Yukon Territory, Canada

    SciTech Connect

    Cole, R.B.; Ridgway, K.D. )

    1993-01-01

    The depositional history of the Eocene-Oligocene Burwash strike-slip basin is characterized by a transition from non-volcanic clastic sedimentation of the Amphitheater Formation to deposition of lavas and volcaniclastic rocks of the overlying lower Wrangell volcanic sequence. The purpose of this paper is twofold: (1) to document the contemporaneous fluvial and volcanic depositional history of a nonmarine strike-slip basin, and (2) to discuss the transition from non-volcanic to volcanic deposition in the context of strike-slip basin evolution. The authors indicate that the onset of volcanism within strike-slip basins can result in major reorganizations of drainage systems as well as changes in sediment sources.

  17. Sequence architecture and lithofacies assemblages of submarine fan deposits in Los Molles Formation (Jurassic), Neuquen Basin, Argentina

    SciTech Connect

    Dean, J.S.

    1986-05-01

    The Neuquen basin is a remnant of the Mesozoic back-arc basin trend that developed along the western margin of South America. It contains a thick, diverse sequence of Jurassic sedimentary strata, whose facies distribution was strongly influenced by syndepositional tectonism. The predominantly dark, laminated shales and siltstones of the Los Molles Formation range from Pliensbachian to Callovian in age and record the progradation of the outer shelf, slope, and basin-plain sediments deposited during the shoaling phase of the lowermost, or Cuyan, Jurassic cycle. Based on outcrop, well, and seismic data, several thick packages of sandstone and conglomerate within the Los Molles are interpreted to represent submarine fan deposits that developed during periods of relative sea level lowstand. Sea level falls were probably related to local synchronous tectonic pulses rather than true eustatic fluctuations. The distribution of coarse-grained fan deposits was apparently strongly controlled by the location of major Jurassic fault trends that stabilized the position of the shelf-slope break through time. Based on the geometry and sequence architecture, two distinct styles of fan development are recognized in the Los Molles sandstones. The most common style (type A) is characterized by sequences that have poorly defined, sand-poor lobes with well-developed channel-levee complexes. Some channels exhibit large-scale accretion surfaces, probably resulting from lateral migration. Thick-bedded arenite facies are limited to amalgamated channel fills, whereas thin-bedded classical turbidites are present as overbank deposits. Type A fans were built by turbidity and fluxoturbidity currents from submarine canyon point sources. The less common fan sequences (type B) lack channeling; they are dominated by thick, massive beds of internally featureless sandstone that are bounded by chaotic slump deposits.

  18. Preliminary paleogeographic reconstruction of the Illinois basin during deposition of the Mississippian Aux Vases Formation: Implications for hydrocarbon recovery

    SciTech Connect

    Cole, R.D. )

    1991-03-01

    Extensive outcrop investigation and selective subsurface study allow definition of Illinois basin paleogeography during deposition of the Mississippian (Valmeyeran-Meramecian) Aux Vases Formation. The results incorporate an integrated approach utilizing field observations and petrographic analysis, wireline logs, subsurface maps, and cores. The Aux Vases Formation depositional system has been determined to be composed of subtidal to intertidal facies. Depositional facies in outcrop are based on rock body geometries, sedimentary structure assemblages, paleocurrent analysis, paleontology of body and trace fossils, facies relationships, and petrography. Depositional facies determined from subsurface data are based on correlation of lithologic interpretations from wireline logs, sand body geometries form isopach maps, and petrography. Specific depositional facies observed in outcrop and core and inferred from wireline logs and isopach maps are offshore bars and tidal channel complexes, extensive subtidal to lower intertidal, ripple-laminated, fine-grained quartzose sandstone. Carbonate facies occur as subtidal grainstones at or near the base of a sequence, or as high energy deposits which have been tidally reworked. This depositional system produces reservoir heterogeneities that complicate efficient hydrocarbon recovery. This diverse facies architecture is modified by tectonic and diagenetic overprinting, further segregating potential producing zones. To significantly improve recovery efficiency, predictions regarding compartmentalization can be used prior to designing a drilling program, an infill drilling program, or an application of enhanced recovery techniques.

  19. Shale depositional processes: Example from the Paleozoic Barnett Shale, Fort Worth Basin, Texas, USA

    NASA Astrophysics Data System (ADS)

    Abouelresh, Mohamed; Slatt, Roger

    2011-12-01

    A long held geologic paradigm is that mudrocks and shales are basically the product of `hemipelagic rain' of silt- and/or clay-sized, detrital, biogenic and particulate organic particles onto the ocean floor over long intervals of time. However, recently published experimental and field-based studies have revealed a plethora of micro-sedimentary features that indicate these common fine-grained rocks also could have been transported and/or reworked by unidirectional currents. In this paper, we add to this growing body of knowledge by describing such features from the Paleozoic Barnett Shale in the Fort Worth Basin, Texas, U.S.A. which suggests transport and deposition was from hyperpycnal, turbidity, storm and/or contour currents, in addition to hemipelagic rain. On the basis of a variety of sedimentary textures and structures, six main sedimentary facies have been defined from four 0.3 meter intervals in a 68m (223 ft) long Barnett Shale core: massive mudstone, rhythmic mudstone, ripple and low-angle laminated mudstone, graded mudstone, clay-rich facies, and spicule-rich facies. Current-induced features of these facies include mm- to cmscale cross- and parallel-laminations, scour surfaces, clastic/biogenic particle alignment, and normal- and inverse-size grading. A spectrum of vertical facies transitions and bed types indicate deposition from waxing-waning flows rather than from steady `rain' of particles to the sea floor. Detrital sponge spicule-rich facies suggests transport to the marine environment as hypopycnal or hyperpycnal flows and reversal in buoyancy by transformation from concentrated to dilute flows; alternatively the spicules could have originated by submarine slumping in front of contemporaneous shallow marine sponge reefs, and then transported basinward as turbidity current flows. The occurrence of dispersed biogenic/organic remains and inversely size graded mudstones also support a hyperpycnal and/or turbidity flow origin for a significant part of

  20. Evaporite deposition in a shallow perennial lake, Qaidam basin, western China

    SciTech Connect

    Schubel, K.A.; Lowenstein, T.K. ); Spencer, R.J. ); Pengxi, Z. )

    1991-03-01

    Evaporites accumulate in ephemeral saline-pans, shallow perennial lakes or lagoons, and deep perennial systems. Continuous brine trench exposures of Holocene evaporites from the Qaidam basin provide criteria for the recognition of shallow perennial lake sediments. Based on Landsat photographs, lateral extent of beds (at least 7 km), and sequence thicknesses (maximum 2.5 m), the paleolake is interpreted to have been less than 2.5 m deep and at least 120 km{sup 2} in area. Sediments consist of laminated siliciclastic mud overlain by mud-halite couplets (mm- to cm-scale layers), which represent one vertical shallowing- and concentrating-upwards sequence. The basal laminite marks the onset of deposition in this shallow perennial paleolake. Syndepositional halite textures and fabrics in the overlying mud-halite couplets include cumulates, rafts, and chevrons, draped by mud laminae, and halite layers truncated by horizontal dissolution surfaces (increasing in frequency upwards). Paleolake brines, determined from fluid inclusion melting temperatures, are Na-Mg-Cl-rich and evolve from 0.84 m Mg{sup 2} to 1.52 m Mg{sup 2+} (near the surface). Combinations of the following criteria may be used for the recognition of shallow, nonstratified, perennial lake sediments: lateral continuity of layers; muds undisrupted by subaerial exposure; vertical bottom-growth of halite; halite layers conformably overlain by mud; halite layers truncated by nonuniformly spaced horizontal dissolution surfaces; erosional scours and channels filled with cross-laminated gypsum, halite, and siliciclastic sand and mud; and salinity fluctuations over small stratigraphic intervals within an overall concentrating-upwards sequence.

  1. Palaeoenvironmental and chronological constraints on the Early Pleistocene mammal fauna from loess deposits in the Linxia Basin, NE Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Zan, Jinbo; Fang, Xiaomin; Zhang, Weilin; Yan, Maodu; Zhang, Tao

    2016-09-01

    The Longdan mammal fauna from the central part of Linxia Basin, NE Tibetan Plateau, is the first Early Pleistocene fauna in China in which the fossils are derived loess deposits, and it provides an excellent opportunity to document mammalian and environmental evolution in Asia. However, the precise age and palaeoenvironmental setting of the fauna are controversial due to the poor exposure of the outcrop section. In the present study, a 105-m-long drill core was obtained from Longdan village and used for detailed magnetostratigraphic dating. The results demonstrate that the late Pliocene- Pleistocene loess deposits in the Longdan section deposited since ca. 3 Ma and that the Longdan fauna has an age range of 2.5-2.2 Ma. In addition, the results of lithological and rock magnetic analyses demonstrate that paleosols are weakly developed throughout the whole core and that in the lower and middle parts the core the magnetic susceptibility and its frequency dependence are relatively low and uniform. These observations, combined with the ecological characteristics of the Longdan fauna, indicate that during the Early Pleistocene the climate in the Longdan area, and even in the Linxia Basin, was sub-humid and that the aeolian dust was frequently subjected to post-depositional reworking by water.

  2. Derivation of S and Pb in phanerozoic intrusion-related metal deposits from neoproterozoic sedimentary pyrite, Great Basin, United States

    USGS Publications Warehouse

    Vikre, P.G.; Poulson, S.R.; Koenig, A.E.

    2011-01-01

    The thick (???8 km), regionally extensive section of Neoproterozoic siliciclastic strata (terrigenous detrital succession, TDS) in the central and eastern Great Basin contains sedimentary pyrite characterized by mostly high d34S values (-11.6 to 40.8%, <70% exceed 10%; 51 analyses) derived from reduction of seawater sulfate, and by markedly radiogenic Pb isotopes ( 207Pb/204Pb <19.2; 15 analyses) acquired from clastic detritus eroded from Precambrian cratonal rocks to the east-southeast. In the overlying Paleozoic section, Pb-Zn-Cu-Ag-Au deposits associated with Jurassic, Cretaceous, and Tertiary granitic intrusions (intrusion-related metal deposits) contain galena and other sulfide minerals with S and Pb isotope compositions similar to those of TDS sedimentary pyrite, consistent with derivation of deposit S and Pb from TDS pyrite. Minor element abundances in TDS pyrite (e.g., Pb, Zn, Cu, Ag, and Au) compared to sedimentary and hydrothermal pyrite elsewhere are not noticeably elevated, implying that enrichment in source minerals is not a precondition for intrusion-related metal deposits. Three mechanisms for transferring components of TDS sedimentary pyrite to intrusion-related metal deposits are qualitatively evaluated. One mechanism involves (1) decomposition of TDS pyrite in thermal aureoles of intruding magmas, and (2) aqueous transport and precipitation in thermal or fluid mixing gradients of isotopically heavy S, radiogenic Pb, and possibly other sedimentary pyrite and detrital mineral components, as sulfide minerals in intrusion-related metal deposits. A second mechanism invokes mixing and S isotope exchange in thermal aureoles of Pb and S exsolved from magma and derived from decomposition of sedimentary pyrite. A third mechanism entails melting of TDS strata or assimilation of TDS strata by crustal or mantle magmas. TDS-derived or assimilated magmas ascend, decompress, and exsolve a mixture of TDS volatiles, including isotopically heavy S and radiogenic Pb

  3. Investigation of mercury deposition and potential sources at six sites from the Pacific Coast to the Great Basin, USA.

    PubMed

    Wright, Genine; Gustin, Mae Sexauer; Weiss-Penzias, Peter; Miller, Matthieu B

    2014-02-01

    The Western Airborne Contaminants Assessment Project showed that USA National Parks had fish mercury (Hg) concentrations above threshold concentrations set for wildlife. Since significant areas of the Western USA are arid, we hypothesized that dry deposition would be important. The primary question was whether sources of Hg were local and thus, easily addressed, or regional (from within the United States), or global (long range transport), and more difficult to address. To investigate this, surrogate surfaces and passive samplers for the measurement of GOM deposition and concentration, respectively, were deployed from the coast of California to the eastern edge of Nevada. Meteorological data, back trajectory modeling, and ozone concentrations were applied to better understand potential sources of Hg. Lowest seasonal mean Hg deposition (0.2 to 0.4 ng m(-2)h(-1)) was observed at low elevation (<100 m) Pacific Coast sites. Highest values were recorded at Lick Observatory, a high elevation coastal site (1,279 m), and Great Basin National Park (2,062 m) in rural eastern Nevada (1.5 to 2.4 ng m(-2)h(-1)). Intermediate values were recorded in Yosemite and Sequoia National Parks (0.9 to 1.2 ng m(-2)h(-1)). Results indicate that local, regional and global sources of air pollution, specifically oxidants, are contributing to observed deposition. At Great Basin National Park air chemistry was influenced by regional urban and agricultural emissions and free troposphere inputs. Dry deposition contributed ~2 times less Hg than wet deposition at the coastal locations, but 3 to 4 times more at the higher elevation sites. Based on the spatial trends, oxidation in the marine boundary layer or ocean sources contributed ~0.4 ng m(-2)h(-1) at the coastal locations. Regional pollution and long range transport contributed 1 to 2 ng m(-2)h(-1) to other locations, and the source of Hg is global and as such, all sources are important to consider.

  4. Tectonic and unroofing history of Neogene Manantiales foreland basin deposits, Cordillera Frontal (32°30'S), San Juan Province, Argentina

    NASA Astrophysics Data System (ADS)

    Pérez, Daniel J.

    2001-12-01

    The Miocene Manantiales foreland basin is located in Cordillera Frontal of San Juan, between 32°30' and 33°S. The unroofing study of the synorogenic Miocene deposits provides information about the structural evolution of Cordón de La Ramada fold-and-thrust belt. These Tertiary deposits are represented by the Chinches Formation and comprise seven members (Tc0-Tc6). They are the result of the uplift of Mesozoic sequences that crop out in La Ramada fold-and-thrust belt of the Cordillera Principal. Quaternary deposits unconformably overlying the Chinches Formation are composed of granitic and rhyolitic blocks, and represent the final uplift of the Cordón del Espinacito and a series of out-of-sequence thrusts. The unroofing studies also provide sufficient information to establish the out-of-sequence timing of the deformation at this latitude. Initial deposition of the Tertiary deposits can be dated at about 20 Ma, or early Miocene. Andesitic lavas dated in 9.2±0.3, 10.7±0.7, and 12.7±0.7 Ma unconformably overlie the structure of La Ramada fold-and-thrust belt. These facts constrain the uplift of the High Andes between 20 and 10 Ma at this latitude. The unconformity between Tertiary and Quaternary deposits suggests final uplift during Pliocene-Pleistocene times.

  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. Shelf-fed turbidite system model and its application to the Oligocene deposits of the Campos Basin, Brazil

    SciTech Connect

    Peres, W.E. )

    1993-01-01

    Despite the large number of models involving the genesis and sedimentary facies of deep-water sandstones, none of these models adequately explain the origin and evolution of the extremely clean, widespread (over 6000 km[sup 2]), predominantly massive, thick (over 150 m), blanket-like sandstones deposited in the deep-water environment of the Campos Basin during the Oligocene. Consequently, to explain this sandstone, the author proposes a shelf-fed turbidite system model, which is strongly based on the Campos Basin data set. The basic framework necessary for the development of a shelf-fed turbidite system includes (1) deposition of a large volume of clastics during the buildup of a shelf-sand-rich unit, which later constitutes the main source of sediment for the system, (2) localized tectonic pulses that modify the outer shelf declivity and trigger mass flows; and (3) a relative fall of sea level, which causes the subaqueous exposure of the shelf sediments to reworking in a shallow, high-energy marine environment. These three basic elements are equally important for shelf-fed turbidity system development, but relative sea level position controls the development of the progradational, aggradational, and retrogradational depositional phases within the system. Submarine canyons commonly are scoured during all three phases on the outer shelf and lower slope environments. The shelf-fed turbidite system model may apply to other sedimentary basins, principally to those of the Atlantic-continental margins that have a thick evaporite sublayer. Halokinesis can provide the necessary room for the shelf sedimentary-unit buildup, the tectonic pulses that trigger the flows, and even localized relative sea level oscillations that can accelerate or abort any one of the depositional phases of the system. 25 refs., 26 figs.

  7. Chapter B: Regional Geologic Setting of Late Cenozoic Lacustrine Diatomite Deposits, Great Basin and Surrounding Region: Overview and Plans for Investigation

    USGS Publications Warehouse

    Wallace, Alan R.

    2003-01-01

    Freshwater diatomite deposits are present in all of the Western United States, including the Great Basin and surrounding regions. These deposits are important domestic sources of diatomite, and a better understanding of their formation and geologic settings may aid diatomite exploration and land-use management. Diatomite deposits in the Great Basin are the products of two stages: (1) formation in Late Cenozoic lacustrine basins and (2) preservation after formation. Processes that favored long-lived diatom activity and diatomite formation range in decreasing scale from global to local. The most important global process was climate, which became increasingly cool and dry from 15 Ma to the present. Regional processes included tectonic setting and volcanism, which varied considerably both spatially and temporally in the Great Basin region. Local processes included basin formation, sedimentation, hydrology, and rates of processes, including diatom growth and accumulation; basin morphology and nutrient and silica sources were important for robust activity of different diatom genera. Only optimum combinations of these processes led to the formation of large diatomite deposits, and less than optimum combinations resulted in lakebeds that contained little to no diatomite. Postdepositional processes can destroy, conceal, or preserve a diatomite deposit. These processes, which most commonly are local in scale, include uplift, with related erosion and changes in hydrology; burial beneath sedimentary deposits or volcanic flows and tuffs; and alteration during diagenesis and hydrothermal activity. Some sedimentary basins that may have contained diatomite deposits have largely been destroyed or significantly modified, whereas others, such as those in western Nevada, have been sufficiently preserved along with their contained diatomite deposits. Future research on freshwater diatomite deposits in the Western United States and Great Basin region should concentrate on the regional

  8. Estimation of groundwater use for a groundwater-flow model of the Lake Michigan Basin and adjacent areas, 1864-2005

    USGS Publications Warehouse

    Buchwald, Cheryl A.; Luukkonen, Carol L.; Rachol, Cynthia M.

    2010-01-01

    The U.S. Geological Survey, at the request of Congress, is assessing the availability and use of the Nation's water resources to help characterize how much water is available now, how water availability is changing, and how much water can be expected to be available in the future. The Great Lakes Basin Pilot project of the U.S. Geological Survey national assessment of water availability and use focused on the Great Lakes Basin and included detailed studies of the processes governing water availability in the Great Lakes Basin. One of these studies included the development of a groundwater-flow model of the Lake Michigan Basin. This report describes the compilation and estimation of the groundwater withdrawals in those areas in Wisconsin, Michigan, Indiana, and Illinois that were needed for the Lake Michigan Basin study groundwater-flow model. These data were aggregated for 12 model time intervals spanning 1864 to 2005 and were summarized by model area, model subregion, category of water use, aquifer system, aquifer type, and hydrogeologic unit model layer. The types and availability of information on groundwater withdrawals vary considerably among states because water-use programs often differ in the types of data collected and in the methods and frequency of data collection. As a consequence, the methods used to estimate and verify the data also vary. Additionally, because of the different sources of data and different terminologies applied for the purposes of this report, the water-use data published in this report may differ from water-use data presented in other reports. These data represent only a partial estimate of groundwater use in each state because estimates were compiled only for areas in Wisconsin, Michigan, Indiana, and Illinois within the Lake Michigan Basin model area. Groundwater-withdrawal data were compiled for both nearfield and farfield model areas in Wisconsin and Illinois, whereas these data were compiled primarily for the nearfield model

  9. A geodynamic model of the evolution of the Arctic basin and adjacent territories in the Mesozoic and Cenozoic and the outer limit of the Russian Continental Shelf

    NASA Astrophysics Data System (ADS)

    Laverov, N. P.; Lobkovsky, L. I.; Kononov, M. V.; Dobretsov, N. L.; Vernikovsky, V. A.; Sokolov, S. D.; Shipilov, E. V.

    2013-01-01

    The tectonic evolution of the Arctic Region in the Mesozoic and Cenozoic is considered with allowance for the Paleozoic stage of evolution of the ancient Arctida continent. A new geodynamic model of the evolution of the Arctic is based on the idea of the development of upper mantle convection beneath the continent caused by subduction of the Pacific lithosphere under the Eurasian and North American lithospheric plates. The structure of the Amerasia and Eurasia basins of the Arctic is shown to have formed progressively due to destruction of the ancient Arctida continent, a retained fragment of which comprises the structural units of the central segment of the Arctic Ocean, including the Lomonosov Ridge, the Alpha-Mendeleev Rise, and the Podvodnikov and Makarov basins. The proposed model is considered to be a scientific substantiation of the updated Russian territorial claim to the UN Commission on the determination of the Limits of the Continental Shelf in the Arctic Region.

  10. Depositional history of Dakota Sandstone, Moxa Arch and vicinity, southwestern Wyoming - implications for early evolution of Cretaceous Foreland Basin

    SciTech Connect

    Ryer, T.A.; McClurg, J.J.; Muller, M.M.

    1987-05-01

    The Dakota Sandstone in the vicinity of the Moxa Arch is divided into upper and lower parts using an unconformity identified on the basis of petrographic evidence and facies relationships. The unconformity is believed to be of subaerial origin and came into being during a pronounced lowering of relative sea level during the late Albian. The lower Dakota consists predominantly of shoreline sandstone and offshore marine shale on the northern part of the Moxa Arch; it consists predominantly of fluvial strata on the southern part of the arch. Meander belts of the lower Dakota trend north-northeastward toward the west-northwest-trending shoreline of the Thermopolis Sea. The upper Dakota consists predominantly of strata deposited in low-energy, restricted marine paleoenvironments that came into being during gradual transgression of the Shell Creek/Mowery Sea. Barrier-island sandstones bodies are elongate toward the northeast, indicating that the shoreline trended in that direction. The reorientation of the shoreline from west-northwest-trending in the lower Dakota to northeast-trending in the upper Dakota is attributed to acceleration in the rate of subsidence in the foreland basin. The Shell Creek Sea advanced down the eastern side of the foreland basin, transgressing over lacustrine deposits that accumulated there during the low-stand of sea level. The Moxa Arch appears to have served as the eastern hinge of the foreland basin during the Dakota; only later, in the Late Cretaceous, did it assume the characteristics of a foreland welt.

  11. New data on mammoth fauna mammals in the central Lena River basin (Yakutia, Lenskie Stolby National Nature Park and adjacent areas)

    NASA Astrophysics Data System (ADS)

    Boeskorov, G. G.; Nogovitsyn, P. R.; Mashchenko, E. N.; Belolyubsky, I. N.; Stepanov, A. D.; Plotnikov, V. V.; Protopopov, A. V.; Shchelchkova, M. V.; van der Plicht, J.; Solomonov, N. G.

    2016-07-01

    This paper considers the data on new findings of mammoth fauna remains in the Middle Lena basin used to specify the species composition of large Late Neopleistocene mammals represented by eleven species. The obtained range of radiocarbon dates made it possible to state that mass burials of Pleistocene mammal remains were formed in the region during the Karginsk Interstadial (24 000-55 000 years ago).

  12. Selected data on characteristics of glacial-deposit and carbonate-rock aquifers, midwestern basins and arches region

    USGS Publications Warehouse

    Joseph, R.L.; Eberts, S.M.

    1994-01-01

    In 1988, the Geological Survey (USGS) began study to examine the hydrogeologic framework, ground-water-flow systems, water chemistry, and withdrawal response of aquifers in glacial deposits and carbonate rock in the Midwestern Basins and Arches Region in western Ohio and eastern Indiana. As part of this study, data from pumped-well tests and instantaneous-rechange tests (slug tests) of wells completed in the glacial-deposit and carbonate-rock aquifers were compiled from reports and information on file with State agencies, environmental consulting firms, drilling firms, municipalities, universities, and the USGS. The data, from 73 counties in Ohio and Indiana, were entered into a computerized data base in a spreadsheet format and subsequently into a geographic information system (GIS). Aquifer-characteristics data from this compilation include the results of 105 pumped-well tests and 39 slug tests in wells completed in glacial deposits, 174 pumped-well tests in wells completed in the carbonate-rock aquifer, and 4 slug tests in wells completed in limestones and shales of Ordovician age. Transmissivities from the pumped-well tests in wells completed in glacial till and glacial-deposit aquifers (sands and gravels) range from 1.54 to 69,700 feet squared per day. Storage coefficients or specific yields range from 0.00002 to 0.38 at these wells. Horizontal-hydraulic conductivities from the slug tests in wells completed in glacial-deposit aquifers range from 0.33 to 1,000 feet per day. Transmissivities from the pumped-well tests in wells completed in the carbonate-rock aquifer range from 70 to 52,000 feet squared per day. Storage coefficient or specific yields at these wells range from 0.00001 to 0.05. Horizontal hydraulic conductivities from the slug tests in wells completed in limestones and shales of Ordovician age range from 0.0016 to 12 feet per day. These data are summarized in tables and figures within this report. The collection and compilation of selected aquifer

  13. Discovery of an outcropping Mass Transport Deposit (MTD) in the Palaeogene subalpine synclines of southeastern France: Implications on flexural sub-basin deformation

    NASA Astrophysics Data System (ADS)

    Mulder, Thierry; Etienne, Samuel

    2014-01-01

    We document the sedimentary facies of a large Mass Transport Deposit (MTD) within the sand-rich sediment gravity flow-dominated deposits of the Eocene-Oligocene south-western Alpine forelands (Annot Sandstone system). The MTD with an approximated volume of several hundreds of cubic kilometres fills a sub-basin located in the Mont-Tournairet confined sub-basin. Autochthonous facies are very typical sediment gravity-flow deposits (thin-bedded classical turbidites and thick-bedded hyperconcentrated to concentrated flow deposits) that stratigraphically belong to the Annot Sandstone infill. Slumps and internal metre-large fold axes of the deformed stratigraphic intervals indicate a main transport direction towards the northwest. The seafloor instability that led to the mass-flow events within the Mont-Tournairet sub-basin could have been favoured by high sedimentation rates in a small, confined and tectonically active sub-basin, possibly enhanced by local structural deformation associated with the Triassic evaporites on the eastern side of the Mont-Tournairet confined basin. The presence of the MTD suggests that a period of increased flexural subsidence rate and basin deformation occurred in this portion of the subalpine foreland basin. Therefore, the MTD forms a stratigraphic marker of a period of tectonic activity.

  14. Seismites in continental sand sea deposits of the Late Cretaceous Caiuá Desert, Bauru Basin, Brazil

    NASA Astrophysics Data System (ADS)

    Fernandes, Luiz Alberto; de Castro, Alice Bonatto; Basilici, Giorgio

    2007-07-01

    Two large-scale sediment deformation structures, minor fold occurrences in cross-bedded sand dune deposits and complex convolute folds, are observed in red sandstones, in a zone about 1.5 km long in floodway cuts at the Sérgio Motta/Porto Primavera dam, São Paulo state, Brazil. The most important structures are confined to planar zones, up to 10 m thick, in undeformed dune foreset strata were they can be traced laterally for about 50-60 m. The sandstones are part of the Rio Paraná Formation, Caiuá Group, which accumulated in a great sand sea of about 100,000 km 2. The Caiuá Desert developed during the Late Cretaceous in the southern part of the Bauru Basin, an intracontinental subsiding area in the central-southern part of the South-American Platform. The basin was filled by a sandy sequence about 300 m thick. The sand sea deposits correspond to the Caiuá Group and comprise: a) deposits of dry sand sheets (Santo Anastácio Formation), b) deposits of medium-sized dunes and humid interdunes of the sand sea peripheral zones (Goio Erê Formation), and c) deposits of large-sized complex aeolian dunes and draas, that correspond to the central part of the inland sand sea (Rio Paraná Formation). The deformations in the sediments are attributed to the effects of fluidization, liquefaction and shear stress, which are interpreted as being earthquake-induced structures, mainly because: (1) the deformed horizons are confined between undeformed cross-bedded strata, (2) the complex convolute folds sometimes include nappe-like structures that overlie foreset facies, (3) during the Bauru Basin infilling there was tectonic activity associated with alkaline volcanism on the borders of the basin and related silicification in the central-southern part. The main silicification zones are aligned to regional lineaments that cross the area near the large-scale sedimentary deformation structures.

  15. Ambient concentration and dry deposition of major inorganic nitrogen species at two urban sites in Sichuan Basin, China.

    PubMed

    Wang, Huanbo; Yang, Fumo; Shi, Guangming; Tian, Mi; Zhang, Leiming; Zhang, Liuyi; Fu, Chuan

    2016-12-01

    To assess pollution levels of major inorganic nitrogen species and their atmospheric deposition input to sensitive ecosystems in Sichuan Basin, southwest China, ambient concentrations of oxidized (NOy ∼ NO2, HNO3, NO3(-)) and reduced (NHx = NH3, NH4(+)) nitrogen species were collected at two urban sites during four one-month periods, each in a different season from July 2014 to April 2015. Estimated annual mean concentration of NOy was 20.3 and 13.5 μg N m(-3) in Chengdu and Wanzhou, respectively, and NHx was 16.9 and 13.6 μg N m(-3), respectively. Back trajectory cluster analysis indicated that high levels of NOy and NHx in Chengdu were mainly caused by local emissions while those in Wanzhou were caused by both the local emissions and long-range transport of pollutants. On annual basis, NO2 contributed the most to NOy, followed by NO3(-) and HNO3, accounting for 87.5%, 10.5% and 2.0%, respectively, of NOy in Chengdu, and 91.4%, 6.9% and 1.7%, respectively, in Wanzhou. NH3 was the predominant contributor to NHx, contributing 65.6% and 72.2% in Chengdu and Wanzhou, respectively. Dry deposition fluxes were estimated using the inferential method with measured ambient concentrations and modelled dry deposition velocities. The total inorganic nitrogen dry deposition flux was estimated to be 21.4 and 8.5 kg N ha(-1) yr(-1), with 44.3% and 41.4% from NOy in Chengdu and Wanzhou, respectively. NO2 and NH3 each contributed about 80% of NOy and NHx dry deposition, respectively. Wet deposition was only collected in Wanzhou, where the annual wet deposition of NO3(-) and NH4(+) was 4.5 and 15.7 kg N ha(-1) yr(-1), respectively. The total wet plus dry deposition was 28.7 kg N ha(-1) yr(-1) in Wanzhou with 72.2% from reduced nitrogen. Therefore, controlling NH3 emissions from agricultural, traffic, waste containers and sewage system sources would be effective to reduce the total nitrogen deposition in the Sichuan Basin area.

  16. Seismic responses and controlling factors of Miocene deepwater gravity-flow deposits in Block A, Lower Congo Basin

    NASA Astrophysics Data System (ADS)

    Wang, Linlin; Wang, Zhenqi; Yu, Shui; Ngia, Ngong Roger

    2016-08-01

    The Miocene deepwater gravity-flow sedimentary system in Block A of the southwestern part of the Lower Congo Basin was identified and interpreted using high-resolution 3-D seismic, drilling and logging data to reveal development characteristics and main controlling factors. Five types of deepwater gravity-flow sedimentary units have been identified in the Miocene section of Block A, including mass transport, deepwater channel, levee, abandoned channel and sedimentary lobe deposits. Each type of sedimentary unit has distinct external features, internal structures and lateral characteristics in seismic profiles. Mass transport deposits (MTDs) in particular correspond to chaotic low-amplitude reflections in contact with mutants on both sides. The cross section of deepwater channel deposits in the seismic profile is in U- or V-shape. The channel deposits change in ascending order from low-amplitude, poor-continuity, chaotic filling reflections at the bottom, to high-amplitude, moderate to poor continuity, chaotic or sub-parallel reflections in the middle section and to moderate-weak amplitude, good continuity, parallel or sub-parallel reflections in the upper section. The sedimentary lobes are laterally lobate, which corresponds to high-amplitude, good-continuity, moundy reflection signatures in the seismic profile. Due to sediment flux, faults, and inherited terrain, few mass transport deposits occur in the northeastern part of the study area. The front of MTDs is mainly composed of channel-levee complex deposits, while abandoned-channel and lobe-deposits are usually developed in high-curvature channel sections and the channel terminals, respectively. The distribution of deepwater channel, levee, abandoned channel and sedimentary lobe deposits is predominantly controlled by relative sea level fluctuations and to a lesser extent by tectonism and inherited terrain.

  17. Ichnological constraints on the depositional environment of the Sawahlunto Formation, Kandi, northwest Ombilin Basin, west Sumatra, Indonesia

    NASA Astrophysics Data System (ADS)

    Zonneveld, J.-P.; Zaim, Y.; Rizal, Y.; Ciochon, R. L.; Bettis, E. A.; Aswan; Gunnell, G. F.

    2012-02-01

    A low diversity trace fossil assemblage is described from the Oligocene Sawahlunto Formation near Kandi, in the northwestern part of the Ombilin Basin in western Sumatra, Indonesia. This trace fossil assemblage includes six ichnogenera attributed to invertebrate infaunal and epifaunal activities ( Arenicolites, Diplocraterion, Planolites, Monocraterion/ Skolithos and Coenobichnus) and two ichnotaxa attributed to vertebrate activity (avian footprints: two species of Aquatilavipes). Arenicolites, Diplocraterion and Monocraterion/ Skolithos record the suspension feeding activities of either arthropods (most likely amphipods) or vermiform organisms. Planolites reflects the presence of an infaunal deposit feeder. Coenobichnus records the walking activities of hermit crabs. Both the Coenobichnus and the avian footprints record the surficial detritus scavenging of epifaunal organisms within a subaerial setting. These traces occur within a fine-grained sandstone succession characterized by planar laminae and low-relief, asymmetrical, commonly mud-draped (locally bidirectional) ripples. The presence of traces attributable to suspension feeders implies deposition in a subaqueous setting. Their occurrence (particularly the presence of Arenicolites and Diplocraterion) in a sandstone bed characterized by mud-draped and bidirectional ripples implies emplacement in a tidally-influenced marine to marginal marine setting. Co-occurrence of these traces with well-preserved avian footprints ( Aquatilavipes) further implies periodic subaerial exposure. Thus, it is most likely that the Sawahlunto Formation near Kandi records deposition within an intertidal flat setting. Definitive evidence of marine influences in the Oligocene interval of the Ombilin Basin implies a more complex tectono-stratigraphic history than has previously been implied.

  18. Late Miocene sedimentary record of the Danube/Kisalföld Basin: interregional correlation of depositional systems, stratigraphy and structural evolution

    NASA Astrophysics Data System (ADS)

    Sztanó, Orsolya; Kováč, Michal; Magyar, Imre; Šujan, Michal; Fodor, László; Uhrin, András; Rybár, Samuel; Csillag, Gábor; Tőkés, Lilla

    2016-12-01

    The Danube / Kisalföld Basin is the north-western sub-basin of the Pannonian Basin System. The lithostratigraphic subdivision of the several-km-thick Upper Miocene to Pliocene sedimentary succession related to Lake Pannon has been developed independently in Slovakia and Hungary. A study of the sedimentary formations across the entire basin led us to claim that these formations are identical or similar between the two basin parts to such an extent that their correlation is indeed a matter of nomenclature only. Nemčiňany corresponds to the Kálla Formation, representing locally derived coarse clastics along the basin margins (11- 9.5 Ma). The deep lacustrine sediments are collectively designated the Ivanka Formation in Slovakia, while in Hungary they are subdivided into Szák (fine-grained transgressive deposits above basement highs, 10.5 - 8.9 Ma), Endrőd (deep lacustrine marls, 11.6 -10 Ma), Szolnok (turbidites, 10.5 - 9.2 Ma) and Algyő Formations (fine-grained slope deposits, 10 - 9 Ma). The Beladice Formation represents shallow lacustrine deltaic deposits, fully corresponding to Újfalu (10.5 - 8.7 Ma). The overlying fluvial deposits are the Volkovce and Zagyva Formations (10 - 6 Ma). The synoptic description and characterization of these sediments offer a basin-wide insight into the development of the basin during the Late Miocene. The turbidite systems, the slope, the overlying deltaic and fluvial systems are all genetically related and are coeval at any time slice after the regression of Lake Pannon initiated about 10 Ma ago. All these formations get younger towards the S, SE as the progradation of the shelf-slope went on. The basin got filled up to lake level by 8.7 Ma, since then fluvial deposition dominated.

  19. Aminostratigraphy of Middle and Late Pleistocene deposits in The Netherlands and the southern part of the North Sea Basin

    NASA Astrophysics Data System (ADS)

    Meijer, T.; Cleveringa, P.

    2009-09-01

    A review of all available amino acid racemization D (alloisoleucine)/L (isoleucine) data from the whole shell of four molluscan species from Late and late Middle Pleistocene deposits of the Netherlands is presented. The data allow the distinction of 5 aminostratigraphical units, NAZ (Netherlands Amino Zone) A-E, each representing a temperate stage. The zones are correlated with marine isotope stages 1, 5e, 7, 9, and 11 respectively. Apart from NAZ-D (MIS 9), in all aminozones the marine transgression reached the present-day onshore area of the Netherlands. The transgression during NAZ-C (Oostermeer Interglacial: MIS 7) seems to be at least as widespread as its counterpart during NAZ-B (Eemian: MIS 5e) in the southern bight of the North Sea Basin. The stratigraphic position of the Oostermeer Interglacial is just below deposits of the Drente phase of the Saalian and because of this position the interglacial marine deposits have formerly erroneously considered to be of Holsteinian age. Neede, the 'classic' Dutch Holsteinian site, is dated in NAZ-E (MIS 11), like Noordbergum. Although the validity of these zones has been checked with independent data, some overlap between succeeding zones may occur. The relation between amino acid data from elsewhere in the North Sea Basin and the Netherlands amino zonation is discussed. The deposits at the Holsteinian stratotype Hummelsbüttel in North West Germany are dated in NAZ-D. This interglacial correlates with MIS 9. The Belvédère Interglacial, which is of importance for its archaeology, is in NAZ-D (MIS 9) and therefore of Holsteinian age as well. The lacustroglacial 'pottery clays' in the Noordbergum area are deposits from two glacial stages, which can be correlated with MIS 8 and 10 (the Elsterian). The pottery clay that is considered equivalent to the German 'Lauenburger Ton' correlates with MIS 10.

  20. The Miocene Sommières basin, SE France: Bioclastic carbonates in a tide-dominated depositional system

    NASA Astrophysics Data System (ADS)

    Reynaud, Jean-Yves; James, Noël P.

    2012-12-01

    The Miocene Sommières Basin in SE France is a semi-enclosed depression that was connected to the Mediterranean Sea by a flooded paleo-incised valley and then filled by a suite of sediments comprising carbonate grains coming from temperate factories that were largely deposited in tidal-dominated paleoenvironments. The strata are partitioned into two sequences that reflect repeated flooding of the incised valley system, one of several similar situations in this region of France. The carbonate grains are mostly bioclasts, namely from barnacles, bryozoans, coralline algae (encrusting, branching, and rhodoliths), echinoids, and benthic foraminifers (large and small) with ostracods, sponge spicules and planktic foraminifers prominent in muddy facies. Particles were produced by shallow water carbonate factories on hard substrates (valley walls in particular), associated with subaqueous dunes, and in deeper water basinal settings. Each depositional sequence is underlain by an eroded and bored hard surface that is progressively overlain by TST subaqueous tidal dunes or storm deposits that grade up, in one case, into HST marls (the HST of the upper sequence has been removed by erosion). The lower sequence is ebb tide dominated whereas the upper sequence is flood tide dominated. The succession is interpreted to represent a TST whose tidal currents were focused by the narrow valley and a HST that reflected flooding of the overbanks. This stratigraphic and depositional motif is comparable to that in other spatially separated Neogene paleovalleys that are filled with tide-dominated clastic carbonates in the region. Together with other recently documented similar systems, these limestones constitute an important new group of carbonate sand bodies in the carbonate depositional realm.

  1. Evaluation of the Gas Production Potential of Marine HydrateDeposits in the Ulleung Basin of the Korean East Sea

    SciTech Connect

    Moridis, George J.; Reagan, Matthew T.; Kim, Se-Joon; Seol,Yongkoo; Zhang, Keni

    2007-11-16

    Although significant hydrate deposits are known to exist in the Ulleung Basin of the Korean East Sea, their survey and evaluation as a possible energy resource has not yet been completed. However, it is possible to develop preliminary estimates of their production potential based on the limited data that are currently available. These include the elevation and thickness of the Hydrate-Bearing Layer (HBL), the water depth, and the water temperature at the sea floor. Based on this information, we developed estimates of the local geothermal gradient that bracket its true value. Reasonable estimates of the initial pressure distribution in the HBL can be obtained because it follows closely the hydrostatic. Other critical information needs include the hydrate saturation, and the intrinsic permeabilities of the system formations. These are treated as variables, and sensitivity analysis provides an estimate of their effect on production. Based on the geology of similar deposits, it is unlikely that Ulleung Basin accumulations belong to Class 1 (involving a HBL underlain by a mobile gas zone). If Class 4 (disperse, low saturation accumulations) deposits are involved, they are not likely to have production potential. The most likely scenarios include Class 2 (HBL underlain by a zone of mobile water) or Class 3 (involving only an HBL) accumulations. Assuming nearly impermeable confining boundaries, this numerical study indicates that large production rates (several MMSCFD) are attainable from both Class 2 and Class 3 deposits using conventional technology. The sensitivity analysis demonstrates the dependence of production on the well design, the production rate, the intrinsic permeability of the HBL, the initial pressure, temperature and hydrate saturation, as well as on the thickness of the water zone (Class 2). The study also demonstrates that the presence of confining boundaries is indispensable for the commercially viable production of gas from these deposits.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  3. Sedimentary and structural controls on seismogenic slumping within mass transport deposits from the Dead Sea Basin

    NASA Astrophysics Data System (ADS)

    Alsop, G. I.; Marco, S.; Weinberger, R.; Levi, T.

    2016-10-01

    Comparatively little work has been undertaken on how sedimentary environments and facies changes can influence detailed structural development in slump sheets associated with mass transport deposits (MTDs). The nature of downslope deformation at the leading edge of MTDs is currently debated in terms of frontally emergent, frontally confined and open-toed models. An opportunity to study and address these issues occurs within the Dead Sea Basin, where six individual slump sheets (S1-S6) form MTDs in the Late Pleistocene Lisan Formation. All six slumps, which are separated from one another by undeformed beds, are traced towards the NE for up to 1 km, and each shows a change in sedimentary facies from detrital-rich in the SW, to more aragonite-rich in the NE. The detrital-rich facies is sourced predominantly from the rift margin 1.5 km further SW, while the aragonite-rich facies represents evaporitic precipitation in the hyper saline Lake Lisan. The stacked system of MTDs translates downslope towards the NE and follows a pre-determined sequence controlled by the sedimentary facies. Each individual slump roots downwards into underlying detrital-rich layers and displays a greater detrital content towards the SW, which is marked by increasing folding, while increasing aragonite content towards the NE is associated with more discrete thrusts. The MTDs thin downslope towards the NE, until they pass laterally into undeformed beds at the toe. The amount of contraction also reduces downslope from a maximum of 50% to < 10% at the toe, where upright folds form diffuse 'open-toed' systems. We suggest that MTDs are triggered by seismic events, facilitated by detrital-rich horizons, and controlled by palaeoslope orientation. The frequency of individual failures is partially controlled by local environmental influences linked to detrital input and should therefore be used with some caution in more general palaeoseismic studies. We demonstrate that MTDs display 'open toes' where

  4. The world-class Jinding Zn-Pb deposit: ore formation in an evaporite dome, Lanping Basin, Yunnan, China

    NASA Astrophysics Data System (ADS)

    Leach, David L.; Song, Yu-Cai; Hou, Zeng-Qian

    2016-07-01

    The Jinding Zn-Pb sediment-hosted deposit in western Yunnan, China, is the fourth largest Zn deposit in Asia. Based on field observations of the ore textures, breccias, and the sandstone host rocks, the ores formed in a dome that was created by the diapiric migration of evaporites in the Lanping Basin during Paleogene deformation and thrust loading. Most of the ore occurs in sandstones that are interpreted to be a former evaporite glacier containing a mélange of extruded diapiric material, including breccias, fluidized sand, and evaporites that mixed with sediment from a fluvial sandstone system. A pre-ore hydrocarbon and reduced sulfur reservoir formed in the evaporite glacier that became the chemical sink for Zn and Pb in a crustal-derived metalliferous fluid. In stark contrast to previous models, the Jinding deposit does not define a unique class of ore deposits; rather, it should be classified as MVT sub-type hosted in a diapiric environment. Given that Jinding is a world-class ore body, this new interpretation elevates the exploration potential for Zn-Pb deposit in other diapir regions in the world.

  5. The world-class Jinding Zn-Pb deposit: ore formation in an evaporite dome, Lanping Basin, Yunnan, China

    NASA Astrophysics Data System (ADS)

    Leach, David L.; Song, Yu-Cai; Hou, Zeng-Qian

    2017-03-01

    The Jinding Zn-Pb sediment-hosted deposit in western Yunnan, China, is the fourth largest Zn deposit in Asia. Based on field observations of the ore textures, breccias, and the sandstone host rocks, the ores formed in a dome that was created by the diapiric migration of evaporites in the Lanping Basin during Paleogene deformation and thrust loading. Most of the ore occurs in sandstones that are interpreted to be a former evaporite glacier containing a mélange of extruded diapiric material, including breccias, fluidized sand, and evaporites that mixed with sediment from a fluvial sandstone system. A pre-ore hydrocarbon and reduced sulfur reservoir formed in the evaporite glacier that became the chemical sink for Zn and Pb in a crustal-derived metalliferous fluid. In stark contrast to previous models, the Jinding deposit does not define a unique class of ore deposits; rather, it should be classified as MVT sub-type hosted in a diapiric environment. Given that Jinding is a world-class ore body, this new interpretation elevates the exploration potential for Zn-Pb deposit in other diapir regions in the world.

  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. Revised age of proximal deposits in the Zagros foreland basin and implications for Cenozoic evolution of the High Zagros

    NASA Astrophysics Data System (ADS)

    Fakhari, Mohammad D.; Axen, Gary J.; Horton, Brian K.; Hassanzadeh, Jamshid; Amini, Abdolhossein

    2008-04-01

    The regionally extensive, coarse-grained Bakhtiyari Formation represents the youngest synorogenic fill in the Zagros foreland basin of Iran. The Bakhtiyari is present throughout the Zagros fold-thrust belt and consists of conglomerate with subordinate sandstone and marl. The formation is up to 3000 m thick and was deposited in foredeep and wedge-top depocenters flanked by fold-thrust structures. Although the Bakhtiyari concordantly overlies Miocene deposits in foreland regions, an angular unconformity above tilted Paleozoic to Miocene rocks is expressed in the hinterland (High Zagros). The Bakhtiyari Formation has been widely considered to be a regional sheet of Pliocene-Pleistocene conglomerate deposited during and after major late Miocene-Pliocene shortening. It is further believed that rapid fold growth and Bakhtiyari deposition commenced simultaneously across the fold-thrust belt, with limited migration from hinterland (NE) to foreland (SW). Thus, the Bakhtiyari is generally interpreted as an unmistakable time indicator for shortening and surface uplift across the Zagros. However, new structural and stratigraphic data show that the most-proximal Bakhtiyari exposures, in the High Zagros south of Shahr-kord, were deposited during the early Miocene and probably Oligocene. In this locality, a coarse-grained Bakhtiyari succession several hundred meters thick contains gray marl, limestone, and sandstone with diagnostic marine pelecypod, gastropod, coral, and coralline algae fossils. Foraminiferal and palynological species indicate deposition during early Miocene time. However, the lower Miocene marine interval lies in angular unconformity above ~ 150 m of Bakhtiyari conglomerate that, in turn, unconformably caps an Oligocene marine sequence. These relationships attest to syndepositional deformation and suggest that the oldest Bakhtiyari conglomerate could be Oligocene in age. The new age information constrains the timing of initial foreland-basin development and

  8. Eustatic and tectonic control of deposition of the lower and middle Pennsylvanian strata of the Central Appalachian Basin

    USGS Publications Warehouse

    Chesnut, D.R.

    1997-01-01

    Stratigraphic analysis of Lower and Middle Pennsylvanian rocks of part of the Central Appalachian Basin reveals two orders of cycles and one overall trend in the vertical sequence of coal-bearing rocks. The smallest order cycle, the coal-clastic cycle, begins at the top of a major-resource coal bed and is composed of a vertical sequence of shale, siltstone, sandstone, seat rock, and overlying coal, which, in turn, is overlain by the next coal-clastic sequence. The average duration of the coal-clastic cycle has been calculated to be about 0.4 m.y. The major marine-transgression cycle is composed of five to seven coal-clastic cycles and is distinguished by the occurrence of widespread, relatively thick (generally thicker than 5 m) marine strata at its base. The duration of this cycle has been calculated to be about 2.5 m.y. The Breathitt coarsening-upward trend describes the general upward coarsening of the Middle Pennsylvanian part of the Breathitt Group. The Breathitt Group includes eight major marine-transgression cycles, and was deposited during a period of approximately 20 m.y. The average duration of coal-clastic cycles is of the same order of magnitude (105 year) as the Milankovitch orbital-eccentricity cycles, and matches the 0.4 m.y. second-order eccentricity cycle (Long Earth-Eccentricity cycle). These orbital periodicities are thought to modulate glacial stages and glacio-eustatic levels. The calculated periodicities of the coal-clastic cycles can be used as evidence for glacio-eustatic control of the coal-bearing rocks of the Appalachian Basin. The 2.5-m.y. periodicity of the major marine-transgression cycle does not match any known orbital or tectonic cycle; the cause of this cycle is unknown, but it might represent episodic thrusting in the orogen, propagation of intraplate stresses, or an unidentified orbital cycle. The Breathitt coarsening-upward trend is interpreted to represent the increasing intensity and proximity of the Alleghenian Orogeny

  9. Franciscan olistoliths in Upper Cretaceous conglomerate deposits, Western Transverse Ranges, California: Implications for basin morphology and tectonic history

    SciTech Connect

    Reed, W.E.; Campbell, M.D. . Dept. of Earth and Space Sciences)

    1993-04-01

    Compositional analyses reveal that Upper Cretaceous sediments exposed in the Western Transverse Ranges of CA were deposited in submarine fan systems in a forearc basin. Point count data suggest a magmatic arc/recycled orogen as the dominant provenance for these sediments. Paleocurrent measurements from conglomerates in these sediments yield a northerly transport direction. Removal of ca. 90[degree] of clockwise rotation and 70 km of right-lateral slip restore this section to a position west of the San Diego area. The forearc basin would have had a N-S orientation, with the bulk of sediments supplied by the Peninsular Ranges to the east. Evidence of the erosion of the accretionary wedge is provided by the presence of large, internally stratified olistoliths of Franciscan material interbedded with and surrounded by upper Cretaceous conglomerate. Petrographic, quantitative SEM, and microprobe analyses indicate the presence of diagnostic Franciscan mineralogy, including glaucophane, riebeckite, lawsonite, and serpentine. Olistoclasts of chert, jadeitic graywacke, serpentine, and blueschist are found intermixed with the conglomerates in close association with the olistoliths. This association provides strong field evidence that recirculation of melange material within the subduction zone was active and well-established by late Cretaceous time. Inferences regarding the forearc system morphology can be drawn from these observations. The occurrence of coarse, easterly-derived conglomerates surrounded by large, stratified, but sheared, westerly-derived Franciscan debris, suggests a narrow, relatively steep-sided basin. Paleocurrent measurements gave no indication of axial transport within the basin. This morphology suggests that, in late Cretaceous time, the forearc basin was youthful, with a narrow arc-trench gap. Thus, relative convergence rates between the North American and Pacific plates were possibly slower than Tertiary convergence rates.

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

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

    We determine the deep structure of the eastern Algerian basin and its southern margin in the Annaba region (easternmost Algeria), to better constrain the plate kinematic reconstruction in this region. This study is based on new geophysical data collected during the SPIRAL cruise in 2009, which included a wide-angle, 240-km-long, onshore-offshore seismic profile, multichannel seismic reflection lines and gravity and magnetic data, complemented by the available geophysical data for the study area. The analysis and modelling of the wide-angle seismic data including refracted and reflected arrival travel times, and integrated with the multichannel seismic reflection lines, reveal the detailed structure of an ocean-to-continent transition. In the deep basin, there is an ˜5.5-km-thick oceanic crust that is composed of two layers. The upper layer of the crust is defined by a high velocity gradient and P-wave velocities between 4.8 and 6.0 km s-1, from the top to the bottom. The lower crust is defined by a lower velocity gradient and P-wave velocity between 6.0 and 7.1 km s-1. The Poisson ratio in the lower crust deduced from S-wave modelling is 0.28, which indicates that the lower crust is composed mainly of gabbros. Below the continental edge, a typical continental crust with P-wave velocities between 5.2 and 7.0 km s-1, from the top to the bottom, shows a gradual seaward thinning of ˜15 km over an ˜35-km distance. This thinning is regularly distributed between the upper and lower crusts, and it characterizes a rifted margin, which has resulted from backarc extension at the rear of the Kabylian block, here represented by the Edough Massif at the shoreline. Above the continental basement, an ˜2-km-thick, pre-Messinian sediment layer with a complex internal structure is interpreted as allochthonous nappes of flysch backthrusted on the margin during the collision of Kabylia with the African margin. The crustal structure, moreover, provides evidence for Miocene

  11. Isopach and isoresource maps for oil shale deposits in the Eocene Green River Formation for the combined Uinta and Piceance Basins, Utah and Colorado

    USGS Publications Warehouse

    Mercier, Tracey J.; Johnson, Ronald C.

    2012-01-01

    The in-place oil shale resources in the Eocene Green River Formation of the Piceance Basin of western Colorado and the Uinta Basin of western Colorado and eastern Utah are estimated at 1.53 trillion barrels and 1.32 trillion barrels, respectively. The oil shale strata were deposited in a single large saline lake, Lake Uinta, that covered both basins and the intervening Douglas Creek arch, an area of comparatively low rates of subsidence throughout the history of Lake Uinta. Although the Green River Formation is largely eroded for about a 20-mile area along the crest of the arch, the oil shale interval is similar in both basins, and 17 out of 18 of the assessed oil shale zones are common to both basins. Assessment maps for these 17 zones are combined so that the overall distribution of oil shale over the entire extent of Lake Uinta can be studied. The combined maps show that throughout most of the history of Lake Uinta, the richest oil shale was deposited in the depocenter in the north-central part of the Piceance Basin and in the northeast corner of the Uinta Basin where it is closest to the Piceance Basin, which is the only area of the Uinta Basin where all of the rich and lean oil shale zones, originally defined in the Piceance Basin, can be identified. Both the oil shale and saline mineral depocenter in the Piceance Basin and the richest oil shale area in the Uinta Basin were in areas with comparatively low rates of subsidence during Lake Uinta time, but both areas had low rates of clastic influx. Limiting clastic influx rather than maximizing subsidence appears to have been the most important factor in producing rich oil shale.

  12. Metal-rich fluid inclusions provide new insights into unconformity-related U deposits (Athabasca Basin and Basement, Canada)

    NASA Astrophysics Data System (ADS)

    Richard, Antonin; Cathelineau, Michel; Boiron, Marie-Christine; Mercadier, Julien; Banks, David A.; Cuney, Michel

    2016-02-01

    The Paleoproterozoic Athabasca Basin (Canada) hosts numerous giant unconformity-related uranium deposits. The scope of this study is to establish the pressure, temperature, and composition (P-T-X conditions) of the brines that circulated at the base of the Athabasca Basin and in its crystalline basement before, during and after UO2 deposition. These brines are commonly sampled as fluid inclusions in quartz- and dolomite-cementing veins and breccias associated with alteration and U mineralization. Microthermometry and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) data from five deposits (Rabbit Lake, P-Patch, Eagle Point, Millennium, and Shea Creek) complement previously published data for the McArthur River deposit. In all of the deposits investigated, fluid inclusion salinity is between 25 and 40 wt.% NaCl equiv., with compositions displaying a continuum between a "NaCl-rich brine" end-member (Cl > Na > Ca > Mg > K) and a "CaCl2-rich brine" end-member (Cl > Ca ≈ Mg > Na > K). The CaCl2-rich brine has the highest salinity and shows evidence for halite saturation at the time of trapping. The continuum of compositions between the NaCl-rich brine and the CaCl2-rich brine end-members combined with P-T reconstructions suggest anisothermal mixing of the two brines (NaCl-rich brine, 180 ± 30 °C and 800 ± 400 bars; CaCl2-rich brine, 120 ± 30 °C and 600 ± 300 bars) that occurred under fluctuating pressure conditions (hydrostatic to supra-hydrostatic). However, because the two brines were U bearing and therefore oxidized, brine mixing was probably not the driving force for UO2 deposition. Several scenarios are put forward to account for the Cl-Na-Ca-Mg-K composition of the brines, involving combinations of seawater evaporation, halite dissolution, mixing with a halite-dissolution brine, Mg/Ca exchange by dolomitization, Na/Ca exchange by albitization of plagioclase, Na/K exchange by albitization of K-feldspar, and Mg loss by Mg

  13. Tectonic and climate control of oil shale deposition in the Upper Cretaceous Qingshankou Formation (Songliao Basin, NE China)

    NASA Astrophysics Data System (ADS)

    Jia, Jianliang; Liu, Zhaojun; Bechtel, Achim; Strobl, Susanne A. I.; Sun, Pingchang

    2013-09-01

    Oil shales were deposited in the Songliao Basin (NE China) during the Upper Cretaceous period, representing excellent hydrocarbon source rocks. High organic matter (OM) contents, a predominance of type-I kerogen, and a low maturity of OM in the oil shales are indicated by bulk geochemical parameters and biomarker data. A major contribution of aquatic organisms and minor inputs from terrigenous land plants to OM input are indicated by n-alkane distribution patterns, composition of steroids, and organic macerals. Strongly reducing bottom water conditions during the deposition of the oil shale sequences are indicated by low pristane/phytane ratios, high C14-aryl-isoprenoid contents, homohopane distribution patterns, and high V/Ni ratios. Enhanced salinity stratification with mesosaline and alkaline bottom waters during deposition of the oil shales are indicated by high gammacerane index values, low MTTC ratios, high β-carotene contents, low TOC/S ratios, and high Sr/Ba ratios. The stratified water column with anoxic conditions in the bottom water enhanced preservation of OM. Moderate input of detrital minerals during the deposition of the oil shale sequences is reflected by titanium concentrations. In this study, environmental conditions in the paleo-lake leading to OM accumulation in the sediments are related to sequence stratigraphy governed by climate and tectonics. The first Member of the Qingshankou Formation (K2qn1) in the Songliao Basin, containing the oil shale sequence, encompasses a third-order sequence that can be divided into three system tracts (transgressive system tract—TST, highstand system tract—HST, and regressive system tract—RST). Enrichment of OM changed from low values during TST-I to high-moderate values during TST-II/III and HST-I/II. Low OM enrichment occurs during RST-I and RST-II. Therefore, the highest enrichment of OM in the sediments is related to stages of mid-late TST and early HST.

  14. Water-level data for the Albuquerque Basin and adjacent areas, central New Mexico, period of record through September 30, 2014

    USGS Publications Warehouse

    Beman, Joseph E.

    2015-10-21

    An initial network of wells was established by the U.S. Geological Survey (USGS) in cooperation with the City of Albuquerque from April 1982 through September 1983 to monitor changes in groundwater levels throughout the basin. This network consisted of 6 wells with analog-to-digital recorders and 27 wells where water levels were measured monthly in 1983. The network currently (2014) consists of 125 wells and piezometers. (A piezometer is a specialized well open to a specific depth in the aquifer, often of small diameter and nested with other piezometers open to different depths.) The USGS, in cooperation with the Albuquerque Bernalillo County Water Utility Authority, currently (2014) measures and reports water levels from the 125 wells and piezometers in the network; this report presents water-level data collected by USGS personnel at those 125 sites through water year 2014 (October 1, 2013, to September 30, 2014).

  15. Patterns of deep-water coral diversity in the Caribbean Basin and adjacent southern waters: an approach based on records from the R/V Pillsbury expeditions.

    PubMed

    Hernández-Ávila, Iván

    2014-01-01

    The diversity of deep-water corals in the Caribbean Sea was studied using records from oceanographic expeditions performed by the R/V Pillsbury. Sampled stations were sorted according to broad depth ranges and ecoregions and were analyzed in terms of species accumulation curves, variance in the species composition and contributions to alpha, beta and gamma diversity. According to the analysis of species accumulation curves using the Chao2 estimator, more diversity occurs on the continental slope (200-2000 m depth) than on the upper continental shelf (60-200 m depth). In addition to the effect of depth sampling, differences in species composition related to depth ranges were detected. However, the differences between ecoregions are dependent on depth ranges, there were fewer differences among ecoregions on the continental slope than on the upper continental shelf. Indicator species for distinctness of ecoregions were, in general, Alcyonaria and Antipatharia for the upper continental shelf, but also the scleractinians Madracis myriabilis and Cladocora debilis. In the continental slope, the alcyonarian Placogorgia and the scleractinians Stephanocyathus and Fungiacyathus were important for the distinction of ecoregions. Beta diversity was the most important component of gamma diversity in the Caribbean Basin. The contribution of ecoregions to alpha, beta and gamma diversity differed with depth range. On the upper continental shelf, the Southern Caribbean ecoregion contributed substantially to all components of diversity. In contrast, the northern ecoregions contributed substantially to the diversity of the Continental Slope. Strategies for the conservation of deep-water coral diversity in the Caribbean Basin must consider the variation between ecoregions and depth ranges.

  16. Patterns of Deep-Water Coral Diversity in the Caribbean Basin and Adjacent Southern Waters: An Approach based on Records from the R/V Pillsbury Expeditions

    PubMed Central

    Hernández-Ávila, Iván

    2014-01-01

    The diversity of deep-water corals in the Caribbean Sea was studied using records from oceanographic expeditions performed by the R/V Pillsbury. Sampled stations were sorted according to broad depth ranges and ecoregions and were analyzed in terms of species accumulation curves, variance in the species composition and contributions to alpha, beta and gamma diversity. According to the analysis of species accumulation curves using the Chao2 estimator, more diversity occurs on the continental slope (200–2000 m depth) than on the upper continental shelf (60–200 m depth). In addition to the effect of depth sampling, differences in species composition related to depth ranges were detected. However, the differences between ecoregions are dependent on depth ranges, there were fewer differences among ecoregions on the continental slope than on the upper continental shelf. Indicator species for distinctness of ecoregions were, in general, Alcyonaria and Antipatharia for the upper continental shelf, but also the scleractinians Madracis myriabilis and Cladocora debilis. In the continental slope, the alcyonarian Placogorgia and the scleractinians Stephanocyathus and Fungiacyathus were important for the distinction of ecoregions. Beta diversity was the most important component of gamma diversity in the Caribbean Basin. The contribution of ecoregions to alpha, beta and gamma diversity differed with depth range. On the upper continental shelf, the Southern Caribbean ecoregion contributed substantially to all components of diversity. In contrast, the northern ecoregions contributed substantially to the diversity of the Continental Slope. Strategies for the conservation of deep-water coral diversity in the Caribbean Basin must consider the variation between ecoregions and depth ranges. PMID:24671156

  17. Irrigated Acreage Within the Basin and Range Carbonate-Rock Aquifer System, White Pine County, Nevada, and Adjacent Areas in Nevada and Utah

    USGS Publications Warehouse

    Welborn, Toby L.; Moreo, Michael T.

    2007-01-01

    Accurate delineations of irrigated acreage are needed for the development of water-use estimates and in determining water-budget calculations for the Basin and Range carbonate-rock aquifer system (BARCAS) study. Irrigated acreage is estimated routinely for only a few basins in the study area. Satellite imagery from the Landsat Thematic Mapper and Enhanced Thematic Mapper platforms were used to delineate irrigated acreage on a field-by-field basis for the entire study area. Six hundred and forty-three fields were delineated. The water source, irrigation system, crop type, and field activity for 2005 were identified and verified through field reconnaissance. These data were integrated in a geodatabase and analyzed to develop estimates of irrigated acreage for the 2000, 2002, and 2005 growing seasons by hydrographic area and subbasin. Estimated average annual potential evapotranspiration and average annual precipitation also were estimated for each field.The geodatabase was analyzed to determine the spatial distribution of field locations, the total amount of irrigated acreage by potential irrigation water source, by irrigation system, and by crop type. Irrigated acreage in 2005 totaled nearly 32,000 acres ranging from less than 200 acres in Butte, Cave, Jakes, Long, and Tippett Valleys to 9,300 acres in Snake Valley. Irrigated acreage increased about 20 percent between 2000 and 2005 and increased the most in Snake and White River Valleys. Ground-water supplies as much as 80 percent of irrigation water during dry years. Almost 90 percent of the irrigated acreage was planted with alfalfa.

  18. Stratigraphy and reservoir potential of glacial deposits of the Itarare Group (Carboniferous-Permian), Parana basin, Brazil

    SciTech Connect

    Franca, A.B. ); Potter, P.E. )

    1991-01-01

    Drilling in the Parana basin of Brazil in the mid-1980s discovered gas and condensate in the Itarare Group, and showed that glacial deposits in Brazil can contain hydrocarbons. The reservoir potential of the Carboniferous-Permian Itarare Group of the basin is analyzed using new subsurface data from 20 deep wells drilled in the early to middle 1980s. Central to the analysis was the construction of over 3000 km of cross sections based on more than 100 wells, the description of more than 400 m of core, and study of 95 thin sections. Subsurface exploration and mapping of the Itarare are greatly aided by the recognition of three recently defined and described formations and four members, which are traceable for hundreds of kilometers. These units belong to three major glacial cycles in which the pebbly mudstones and shales are seals and glacially related sandstones are reservoirs. The best sandstone reservoirs in the deep subsurface belong to the Rio Segredo Member, the upper-most sandy unit of the Itarare. The Rio Segredo Member is the best petroleum target because it is overlain by thick seals and massive pebbly mudstones and shales, and because it is shallower and less compacted than underlying, more deeply buried sandstones. This member has little detrital matrix and much of its porosity is secondary, developed by carboxylic acid and CO{sub 2} generated when Jurassic-Cretaceous basalts, sills, and dikes were intruded into the Parana basin as Gondwana broke up.

  19. Lithostratigraphy and depositional history of the Late Cenozoic hominid-bearing successions in the Yuanmou Basin, southwest China

    NASA Astrophysics Data System (ADS)

    Urabe, Atsushi; Nakaya, Hideo; Muto, Tetsuji; Katoh, Shigehiro; Hyodo, Masayuki; Shunrong, Xue

    2001-09-01

    Late Cenozoic strata bearing hominids and hominoids are distributed in the Yuanmou Basin, Yunnan, southwest China. Incisors of Homo erectus discovered in these strata in 1965 reportedly show primitive features known in Africa (Hu, Acta geologica sinica 1 (1973, p. 65). However, recent paleomagnetic study has revealed that the age of the hominid correlates to the early Brunhes chron (Hyodo et al., Journal of human evolution (2001), submitted). The lithostratigraphy of the successions that yield many mammalian fossils including those of the hominid, and the record of Equus is re-examined. The successions are divided in ascending order into the Longchuan, Shagou, Gantang (newly proposed Yangliuchun and Daipojing Members) and Yuanmou (newly proposed Dainawu and Niujianbao Members) Formations, based on different lithology and sedimentary facies. The newly proposed depositional systems of the formations are in ascending order, alluvial fan, ephemeral braided river, sandy braided river, ephemeral gravelly braided river and alluvial fan systems. The change in facies and paleocurrents revealed in the successions suggest that the basin was initiated as a syncline basin at ca 3.5 Ma and was completed as an asymmetric half graben by active movement of the eastern marginal fault in the early Middle Pleistocene.

  20. Radiocarbon dating of silica sinter deposits in shallow drill cores from the Upper Geyser Basin, Yellowstone National Park

    USGS Publications Warehouse

    Lowenstern, Jacob B.; Hurwitz, Shaul; McGeehin, John

    2016-01-01

    To explore the timing of hydrothermal activity at the Upper Geyser Basin (UGB) in Yellowstone National Park, we obtained seven new accelerator mass spectrometry (AMS) radiocarbon 14C ages of carbonaceous material trapped within siliceous sinter. Five samples came from depths of 15–152 cm within the Y-1 well, and two samples were from well Y-7 (depths of 24 cm and 122 cm). These two wells, at Black Sand and Biscuit Basins, respectively, were drilled in 1967 as part of a scientific drilling program by the U.S. Geological Survey (White et al., 1975). Even with samples as small as 15 g, we obtained sufficient carbonaceous material (a mixture of thermophilic mats, pollen, and charcoal) for the 14C analyses. Apparent time of deposition ranged from 3775 ± 25 and 2910 ± 30 14C years BP at the top of the cores to about 8000 years BP at the bottom. The dates are consistent with variable rates of sinter formation at individual sites within the UGB over the Holocene. On a basin-wide scale, though, these and other existing 14C dates hint that hydrothermal activity at the UGB may have been continuous throughout the Holocene.

  1. Radiocarbon dating of silica sinter deposits in shallow drill cores from the Upper Geyser Basin, Yellowstone National Park

    NASA Astrophysics Data System (ADS)

    Lowenstern, Jacob B.; Hurwitz, Shaul; McGeehin, John P.

    2016-01-01

    To explore the timing of hydrothermal activity at the Upper Geyser Basin (UGB) in Yellowstone National Park, we obtained seven new accelerator mass spectrometry (AMS) radiocarbon 14C ages of carbonaceous material trapped within siliceous sinter. Five samples came from depths of 15-152 cm within the Y-1 well, and two samples were from well Y-7 (depths of 24 cm and 122 cm). These two wells, at Black Sand and Biscuit Basins, respectively, were drilled in 1967 as part of a scientific drilling program by the U.S. Geological Survey (White et al., 1975). Even with samples as small as 15 g, we obtained sufficient carbonaceous material (a mixture of thermophilic mats, pollen, and charcoal) for the 14C analyses. Apparent time of deposition ranged from 3775 ± 25 and 2910 ± 30 14C years BP at the top of the cores to about 8000 years BP at the bottom. The dates are consistent with variable rates of sinter formation at individual sites within the UGB over the Holocene. On a basin-wide scale, though, these and other existing 14C dates hint that hydrothermal activity at the UGB may have been continuous throughout the Holocene.

  2. Deposition, diagenesis, and maturation of organic matter in rift-basin lacustrine shales of Triassic-Jurassic Newark Supergroup

    SciTech Connect

    Pratt, L.M.

    1989-03-01

    Evaluating the petroleum source potential of rift basins in frontier areas is difficult because rift lakes vary greatly in areal extent, water depth, water chemistry, and longevity. In addition, climatic cycles are often strongly expressed in lacustrine settings. Triassic-Jurassic deposits in the continental rift basins on the Atlantic margin of North America are one of the few cases where lateral and vertical variations in the content (C/sub org/, hydrogen index) and thermal maturity (T/sub max/, R/sub 0/) of bulk organic matter are well documented. Relatively little is known, however, about sulfur content (S/sub org/, S/sub total/) and the composition of biomarkers in these strata. New data on low-maturity shales (R/sub o/ < 0.4%) in the Jurassic portion of the Hartford basin show wide variation in S/sub total//C/sub org/ ratios, suggesting that paleolimnological conditions ranged from fresh to alkaline or saline. Stratigraphic profiles of C/sub org/ and S/sub total/ through individual shale beds indicate rapid and repeated changes in water chemistry during each lacustrine cycle. Bitumens extracted from samples with less than about 0.05% S/sub total/ are characterized by dominance or high abundance of carotanes and extended regular isoprenoids in the saturated hydrocarbons. These biomarkers are probably derived from carotenoid pigments of algae or bacteria. Early diagenesis in the absence of hydrogen sulfide may account for the unusual preservation of extended isoprenoids and carotanes in the bitumen.

  3. Facies analysis and depositional environment of the Ames Marine Member of the Conemaugh Group in the Appalachian Basin

    SciTech Connect

    Al-Qayim, B.A.

    1983-01-01

    The lithologic and paleontological aspects for fifty localities of the Ames Marine Member were examined. The regional stratigraphic reconstruction shows that it is variably composed of limestone and shale, and often associated with a thin basal coal seam. A generalized, composite stratigraphic section of the Ames Member consists of the following units from top to bottom: the Grafton Sandstone, Nonmarine Shale, Upper Ames Shale, Upper Ames Limestone, Middle Ames Shale, Lower Ames Limestone, Lower Ames Shale, Ames Coal, Nonmarine Silty Shale, and Harlem Coal. Harlem coal is commonly the basal coal in Ohio, and the Ames Coal is common in Pennsylvania and West Virginia. Insoluble residue analysis of 223 samples shows that quartz and glauconite are the major and significant residues. The major petrographic components of the Ames rocks are bioclastic grains of echinoderm, brachiopods, molluscs, bryozoa, and foraminifera in a matrix variably composed of clay and calcium carbonate. A quantitative microfacies study applying factor and cluster analysis reveals five basin-wide biofacies and four lithofacies reflecting a gradient from shoreline to an offshore position. The areal and vertical distribution of the different facies reflects the transgression-regression history of the Ames Cycle. A uniform slow eustatic rise of sea level with an early rapid transgression was responsible for the deposition of most of the Ames marine section. The small, upper, underdeveloped regressive section suggests a rapid regression by active prograding deltaic deposits which rapidly terminated the marine conditions over most the the Appalachian Basin.

  4. After a century-Revised Paleogene coal stratigraphy, correlation, and deposition, Powder River Basin, Wyoming and Montana

    USGS Publications Warehouse

    Flores, Romeo M.; Spear, Brianne D.; Kinney, Scott A.; Purchase, Peter A.; Gallagher, Craig M.

    2010-01-01

    The stratigraphy, correlation, mapping, and depositional history of coal-bearing strata in the Paleogene Fort Union and Wasatch Formations in the Powder River Basin were mainly based on measurement and description of outcrops during the early 20th century. Subsequently, the quality and quantity of data improved with (1) exploration and development of oil, gas, and coal during the middle 20th century and (2) the onset of coalbed methane (CBM) development during the late 20th and early 21st centuries that resulted in the drilling of more than 26,000 closely spaced wells with accompanying geophysical logs. The closeness of the data control points, which average 0.5 mi (805 m) apart, made for better accuracy in the subsurface delineation and correlation of coal beds that greatly facilitated the construction of regional stratigraphic cross sections and the assessment of resources. The drillhole data show that coal beds previously mapped as merged coal zones, such as the Wyodak coal zone in the Wyoming part of the Powder River Basin, gradually thinned into several discontinuous beds and sequentially split into as many as 7 hierarchical orders westward and northward. The thinning and splitting of coal beds in these directions were accompanied by as much as a ten-fold increase in the thicknesses of sandstone-dominated intervals within the Wyodak coal zone. This probably resulted from thrust loading by the eastern front of the Bighorn uplift accompanied by vertical displacement along lineaments that caused subsidence of the western axial part of the Powder River Basin during Laramide deformation in Late Cretaceous and early Tertiary time. Accommodation space was thereby created for synsedimentary alluvial infilling that controlled thickening, thinning, splitting, pinching out, and areal distribution of coal beds. Equally important was differential subsidence between this main accommodation space and adjoining areas, which influenced the overlapping, for example, of the

  5. Preliminary measurements of summer nitric acid and ammonia concentrations in the Lake Tahoe Basin air-shed: implications for dry deposition of atmospheric nitrogen.

    PubMed

    Tarnay, L; Gertler, A W; Blank, R R; Taylor, G E

    2001-01-01

    Over the past 50 years, Lake Tahoe, an alpine lake located in the Sierra Nevada mountains on the border between California and Nevada, has seen a decline in water clarity. With significant urbanization within its borders and major urban areas 130 km upwind of the prevailing synoptic airflow, it is believed the Lake Tahoe Basin is receiving substantial nitrogen (N) input via atmospheric deposition during summer and fall. We present preliminary inferential flux estimates to both lake surface and forest canopy based on empirical measurements of ambient nitric acid (HNO3), ammonia (NH3), and ammonium nitrate (NH4NO3) concentrations, in an effort to identify the major contributors to and ranges of atmospheric dry N deposition to the Lake Tahoe Basin. Total flux from dry deposition ranges from 1.2 to 8.6 kg N ha-1 for the summer and fall dry season and is significantly higher than wet deposition, which ranges from 1.7 to 2.9 kg N ha-1 year-1. These preliminary results suggest that dry deposition of HNO3 is the major source of atmospheric N deposition for the Lake Tahoe Basin, and that overall N deposition is similar in magnitude to deposition reported for sites exposed to moderate N pollution in the southern California mountains.

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

    USGS Publications Warehouse

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

    2003-01-01

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

  7. Active transtensional intracontinental basins: Walker Lane in the western Great Basin

    USGS Publications Warehouse

    Jayko, Angela S.; Bursik, Marcus

    2012-01-01

    The geometry and dimensions of sedimentary basins within the Walker Lane are a result of Plio-Pleistocene transtensive deformation and partial detachment of the Sierra Nevada crustal block from the North American plate. Distinct morpho-tectonic domains lie within this active transtensive zone. The northeast end of the Walker Lane is partly buried by active volcanism of the southern Cascades, and adjacent basins are filled or poorly developed. To the south, the basin sizes are moderate, 25–45km × 15–10 km, with narrow 8-12km wide mountain ranges mainly oriented N-S to NNE. These basins form subparallel arrays in discrete zones trending about 300° and have documented clockwise rotation. This is succeeded to the south by a releasing stepover domain ∼85-100km wide, where the basins are elongated E-W to ENE, small (∼15-30km long, 5-15km wide), and locally occupied by active volcanic centers. The southernmost part of the Walker Lane is structurally integrated, with high to extreme relief. Adjacent basins are elongate, 50-200km long and ∼5 -20km wide. Variations in transtensive basin orientations in the Walker Lane are largely attributable to variations in strain partitioning. Large basins in the Walker Lane have 2-6km displacement across basin bounding faults with up to 3 km of clastic accumulation based on gravity and drill hole data. The sedimentary deposits of the basins may include interbedded volcanic deposits with bimodal basaltic and rhyolitic associations. The basins may include lacustrine deposits that record a wide range of water chemistry from cold fresh water conditions to saline-evaporative

  8. Thickness Estimate of Ice-Rich Mantle Deposits on Malea Planum and the Southern Hellas Basin, Mars

    NASA Astrophysics Data System (ADS)

    Zanetti, M.; Hiesinger, H.; Reiss, D.

    2009-04-01

    Latitude-dependent ice-rich surface deposits of dust have been observed to mantle the middle and high latitudes of the Martian surface. Based on observations from previous work from [1], mantle deposits on the southern wall of the Hellas Basin appear significantly thicker than those on Malea Planum. We have attempted to quantify the thickness of the mantle in this region using the measured crater diameter/rim height relationship of partially and completely buried ‘ghost' craters. This method has been successfully used in the past for estimations of mare lava thickness on the Moon [e.g., 2], and dust mantles on Mars [e.g., 3]. Because the dust-ice mantles represent a significant reservoir of presumably H2O ice, quantifying their volume is important for under-standing the current ice budget of the planet, as well as current and paleoclimate depositional re-gimes. The study region is located in Malea Planum and the southern Hellas Basin from ~56°E to 70°E and ~52°S to 70°S. High Resolution Stereo Camera (12.5 m/pxl resolution) and CTX (5 m/pxl resolution) images in this area were examined for mantled impact craters. Where craters appeared to have been completely buried by mantle deposits, or where their crater rims appeared to be just barely visible through the deposit, their crater diameter was measured, and their loca-tion recorded. Crater rim heights (the expected average height of the crater rim above the sur-rounding plains elevation) were calculated from these diameters using the relationship for simple craters of h=0.04D^0.31 from [4]. 3829 craters (diameter range: 0.081km - 5.8 km) were found to be mostly or completely buried. A gridded isopach map was produced based on the calculated rim heights. The method required that certain assumptions be made regarding the craters: 1) Craters are simple, bowl-shaped, and unmodified; 2) Craters formed prior to the emplacement of the mantle; 3) Craters are entirely buried or their rims are barely discernable from

  9. Mapping Evapotranspiration Units in the Basin and Range Carbonate-Rock Aquifer System, White Pine County, Nevada, and Adjacent Areas in Nevada and Utah

    USGS Publications Warehouse

    Smith, J. LaRue; Laczniak, Randell J.; Moreo, Michael T.; Welborn, Toby L.

    2007-01-01

    Accurate estimates of ground-water discharge are crucial in the development of a water budget for the Basin and Range carbonate-rock aquifer system study area. One common method used throughout the southwestern United States is to estimate ground-water discharge from evapotranspiration (ET). ET is a process by which water from the Earth's surface is transferred to the atmosphere. The volume of water lost to the atmosphere by ET can be computed as the product of the ET rate and the acreage of vegetation, open water, and moist soil through which ET occurs. The procedure used in the study groups areas of similar vegetation, water, and soil conditions into different ET units, assigns an average annual ET rate to each unit, and computes annual ET from each ET unit within the outer extent of potential areas of ground-water discharge. Data sets and the procedures used to delineate the ET-unit map used to estimate ground-water discharge from the study area and a qualitative assessment of the accuracy of the map are described in this report.

  10. Dissolved organic carbon content and characteristics in relation to carbon dioxide partial pressure across Poyang Lake wetlands and adjacent aquatic systems in the Changjiang basin.

    PubMed

    Wang, Huaxin; Jiao, Ruyuan; Wang, Fang; Zhang, Lu; Yan, Weijin

    2016-12-01

    Dissolved organic carbon (DOC) plays diverse roles in carbon biogeochemical cycles. Here, we explored the link between DOC and pCO2 using high-performance size-exclusion chromatography (HPSEC) with UV254 detection and excitation emission matrix (EEM) fluorescence spectroscopy to determine the molecular weight distribution (MW) and the spectral characteristics of DOC, respectively. The relationship between DOC and pCO2 was investigated in the Poyang Lake wetlands and their adjacent aquatic systems. The results indicated significant spatial variation in the DOC concentrations, MW distributions, and pCO2. The DOC concentration was higher in the wetlands than in the rivers and lakes. pCO2 was high in wetlands in which the dominant vegetation was Phragmites australis, whereas it was low in wetlands in which Carex tristachya was the dominant species. DOC was divided into five fractions according to MW, as follows: super-low MW (SLMW, <1 kDa); low MW (LMW, 1-2.5 kDa); intermediate MW (IMW, 2.5-3.5 kDa); high MW (HMW, 3.5-6 kDa); and super-high MW (SMW, > 40 kDa). Rivers contained high proportions of HMW and extremely low amounts of SLMW, whereas wetlands had relatively high proportions of SLMW. The proportion of SMW (SMWp) was particularly high in wetlands. We found that pCO2 significantly positively correlated with the proportion of IMW, and significantly negatively correlated with SMWp. These data improve our understanding of the MW of bioavailable DOC and its conversion to CO2. The present results demonstrate that both the content and characteristics of DOC significantly affect pCO2. pCO2 and DOC must be studied further to help understanding the role of the wetland on the regional CO2 budget.

  11. Petroleum potential and over-pressuring in the molassic deposits of the south-eastern part of the South Adriatic Basin

    SciTech Connect

    Gjoka, M.; Dulaj, A.

    1995-08-01

    The southeastern portion of the South Adriatic basin extends onshore in Albania and is filled with a sequence of interbedded clays, sandstones and siltstones of Cenozoic age accumulated under turbiditic, slope, shelf, deltaic and, rarely, continental depositional conditions. Geochemical data suggest a fairly uniform vertical and lateral distribution of organic matter, with TOC values ranging from 0.1 to 0.4 wt%. Average organic matter content is 0.28 wt%. Kerogen is predominantly gas-prone, Type IIIa (Huminite-Inertinite) and IIIb (Inertinite-Huminite), and is thermally immature to marginally mature, even at depths of 6000 m. Vitrinite reflectance (Ro) values range from 0.3 to 0.5; the average geothermal gradient of the region is about 16{degrees}C/100 m. Three main gas zones can be recognized in the Pliocene to Middle Miocene (Serravallian) sequence: (1) a biogenic gas zone at depths of 1200-1500 m; (2) a mixed biogenic-thermogenic zone between 1500 and 4500-W m, and, (3) a thermogenic gas zone below 4500-5000 m. Gas is indigenous and has migrated into the sandstone reservoirs from adjacent shales (syngenetic) or deeper sources (syngenetic-long migration). Gas fields discovered to date are associated with crestal culminations and with the eastern flank of structures. The normal hydrostatic gradient for the Neogene sediments is 0.437 Psi/ft, but overpressures have been encountered in numerous wells and are considered a regional phenomenon. The top of the overpressures crosses stratigraphic boundaries. The gradient is gradual and seem to increase in sequences with sandstone content of 15 to 20%. Steep pressure gradients are found on flanks and plunges of structures. Overpressuring is attributed to the very high sedimentation rate (760 m per million year) during the Neogene and resulting undercompacted shales.

  12. Electrical and well log study of the Plio-Quaternary deposits of the southern part of the Rharb Basin, northern Morocco

    NASA Astrophysics Data System (ADS)

    El Bouhaddioui, Mohamed; Mridekh, Abdelaziz; Kili, Malika; El Mansouri, Bouabid; El Gasmi, El Houssine; Magrane, Bouchaib

    2016-11-01

    The Rharb Basin is located in the NW of Morocco. It is the onshore extension of a lager offshore basin between Kenitra and Moulay Bousselham. The Rharb plain (properly called) extends over an area of 4200 Km2 between two very different structural entities: the unstable Rif domain in the NE and the East and the ''relatively stable'' Meseta domain in the south. The distribution of Pliocene-Quaternary deposits under this plain is complex and was controlled by both tectonics and climatic factors. The main objective of the present work is to define the spatiotemporal evolution of these deposits in the onshore part of the basin and to make a comparison with a sequence analysis defined, for equivalent deposits in the offshore basin, by a previous work. The proposed model allows thus to characterize the geometry of these deposits in the extension of continental shelf under the present day onshore basin, and to explain there is genesis in terms of interactions between eustatic sea level fluctuations, tectonics and sedimentary rates at the mouths of paleo-rivers that had drained the Rharb plain during Pliocene to Quaternary Times.

  13. Relations between clay mineralogy and depositional environment in the Atchafalaya basin and Terrebonne Marsh areas, south-central Louisiana

    SciTech Connect

    Stewart, K.D. ); Patrick, D.M. )

    1990-09-01

    The analyses of nearly 200 vibracore samples taken from Holocene sediments in south-central Louisiana revealed strong statistical relations between clay mineral composition and depositional environment and lithology The samples selected for study were representative of the major depositional environments, which are: backswamp, channel fill, crevasse channel, inland swamp, interdistributary bay, lacustrine or lacustrine delta, marsh, and natural levee. The dominant clay minerals from most to least abundant in both the Atchafalaya basin and Terrebonne Marsh areas were: smectite (70%), illite (18%), kaolinite (10%), and chlorite (1%). The higher concentrations of smectite occurred in the inland swamp (86%) and backswamp (83%), and the lower concentrations were found in the crevasse channel (44%) and lacustrine delta (58%). Generally, the percent smectite was inversely proportional to the relative depositional energy of the environment. The percent illite ranged from a low of 8 in the inland swamp to a high of 37 in the crevasse channel. Kaolinite was most abundant in the lacustrine delta (14%), and least abundant in the inland swamp (5%). Chlorite was 2% or less in most environments; however, the crevasse channel exhibited a concentration of 8%. In terms of lithology, the highest concentration of smectite (78%) occurred in deposits classed as clay, and the lowest (46%) occurred in organic-rich clay. Clay and organic-rich clay, respectively, also exhibited the lowest and highest concentrations of both illite and kaolinite. The high smectite content is attributable to the low energy of the clay deposits, while the low concentrations of smectite in both organic-rich and peat material are due to instability of smectite in low pH environments.

  14. Morphologies and depositional/erosional controls on evolution of Pliocene-Pleistocene carbonate platforms: Northern Carnarvon Basin, Northwest Shelf of Australia

    NASA Astrophysics Data System (ADS)

    Goktas, P.; Austin, J. A.; Fulthorpe, C. S.; Gallagher, S. J.

    2016-08-01

    The detailed morphologies, evolution and termination of latest Neogene tropical carbonate platforms in the Northern Carnarvon Basin (NCB), on the passive margin of the Northwest Shelf (NWS) of Australia, defined based upon mapping using 3D seismic images, reveal the history of local/regional oceanographic processes, fluctuations in relative sea-level and changing climate. Cool-water carbonate deposition, dominant during the early-middle Miocene, was followed by a siliciclastic influx, which prograded across the NWS beginning in the late-middle Miocene, during a period of long-term global sea-level fall. The resulting prograding clinoform sets, interpreted as delta lobes, created relict topographic highs following Pliocene termination of the siliciclastic influx. These highs constituted multiple favorable shallow-water environments for subsequent photozoan carbonate production. Resultant platform carbonate development, in addition to being a response to cessation of siliciclastic influx and the existence of suitable shallow-water substrate, was also influenced by development of the warm-water Leeuwin Current (LC), flowing southwestward along this margin. Four flat-topped platforms are mapped; each platform top is a sequence boundary defined by reflection onlap above and truncation below. Successive platforms migrated southwestward through time, along margin strike. All platforms exhibit predominantly progradational seismic geometries. Mapped tops are ≥10 km wide. Seismic evidence of karst on three of four platform tops, e.g., v-shaped troughs up to 50 m deep and ~1 km wide, and broader basins with areas up to 20 km2, suggests episodic subaerial exposure that may have contributed to platform demise. Platform 4, the most recent, is unique in having interpreted biohermal build-ups superimposed on the progradational platform base. The base of these interpreted patch reefs now lies at a water depth of ~153 m; therefore, we suggest that these reefs developed post

  15. Sedimentology and ichnology of Neogene Coastal Swamp deposits in the Niger Delta Basin, Nigeria

    NASA Astrophysics Data System (ADS)

    Ezeh, Sunny C.; Mode, Wilfred A.; Ozumba, Berti M.; Yelwa, Nura A.

    2016-09-01

    Often analyses of depositional environments from sparse data result in poor interpretation, especially in multipartite depositional settings such as the Niger Delta. For instance, differentiating channel sandstones, heteroliths and mudstones within proximal environments from those of distal facies is difficult if interpretations rely solely on well log signatures. Therefore, in order to achieve an effective and efficient interpretation of the depositional conditions of a given unit, integrated tools must be applied such as matching core descriptions with wireline log signature. In the present paper cores of three wells from the Coastal Swamp depositional belt of the Niger Delta are examined in order to achieve full understanding of the depositional environments. The well sections comprise cross-bedded sandstones, heteroliths (coastal and lower shoreface) and mudstones that were laid down in wave, river and tidal processes. Interpretations were made from each data set comprising gamma ray logs, described sedimentological cores showing sedimentary features and ichnological characteristics; these were integrated to define the depositional settings. Some portions from one of the well sections reveal a blocky gamma ray well log signature instead of a coarsening-upward trend that characterises a shoreface setting while in other wells the signatures for heteroliths at some sections are bell blocky in shaped rather than serrated. Besides, heteroliths and mudstones within the proximal facies and those of distal facies were difficult to distinguish solely on well log signatures. However, interpretation based on sedimentology and ichnology of cores from these facies was used to correct these inconsistencies. It follows that depositional environment interpretation (especially in multifarious depositional environments such as the Niger Delta) should ideally be made together with other raw data for accuracy and those based solely on well log signatures should be treated with

  16. Sequence stratigraphy, geodynamics, and detrital geothermochronology of Cretaceous foreland basin deposits, western interior U.S.A

    NASA Astrophysics Data System (ADS)

    Painter, Clayton S.

    Three studies on Cordilleran foreland basin deposits in the western U.S.A. constitute this dissertation. These studies differ in scale, time and discipline. The first two studies include basin analysis, flexural modeling and detailed stratigraphic analysis of Upper Cretaceous depocenters and strata in the western U.S.A. The third study consists of detrital zircon U-Pb analysis (DZ U-Pb) and thermochronology, both zircon (U-Th)/He and apatite fission track (AFT), of Upper Jurassic to Upper Cretaceous foreland-basin conglomerates and sandstones. Five electronic supplementary files are a part of this dissertation and are available online; these include 3 raw data files (Appendix_A_raw_isopach_data.txt, Appendix_C_DZ_Data.xls, Appendix_C_U-Pb_apatite.xls), 1 oversized stratigraphic cross section (Appendix_B_figure_5.pdf), and 1 figure containing apatite U-Pb concordia plots (Appendix_C_Concordia.pdf). Appendix A is a combination of detailed isopach maps of the Upper Cretaceous Western Interior, flexural modeling and a comparison to dynamic subsidence models as applied to the region. Using these new isopach maps and modeling, I place the previously recognized but poorly constrained shift from flexural to non-flexural subsidence at 81 Ma. Appendix B is a detailed stratigraphic study of the Upper Cretaceous, (Campanian, ~76 Ma) Sego Sandstone Member of the Mesaverde Group in northwestern Colorado, an area where little research has been done on this formation. Appendix C is a geo-thermochronologic study to measure the lag time of Upper Jurassic to Upper Cretaceous conglomerates and sandstones in the Cordilleran foreland basin. The maximum depositional ages using DZ U-Pb match existing biostratigraphic age controls. AFT is an effective thermochronometer for Lower to Upper Cretaceous foreland stratigraphy and indicates that source material was exhumed from >4--5 km depth in the Cordilleran orogenic belt between 118 and 66 Ma, and zircon (U-Th)/He suggests that it was exhumed

  17. Impact of depositional facies on the distribution of diagenetic alterations in the Devonian shoreface sandstone reservoirs, Southern Ghadamis Basin, Libya

    NASA Astrophysics Data System (ADS)

    Khalifa, Muftah Ahmid; Morad, Sadoon

    2015-11-01

    The middle Devonian, shoreface quartz arenites (present-day burial depths 2833-2786 m) are important oil and gas reservoirs in the Ghadamis Basin, western Libya. This integrated petrographic and geochemical study aims to unravel the impact of depositional facies on distribution of diagenetic alterations and, consequently, related reservoir quality and heterogeneity of the sandstones. Eogenetic alterations include the formation of kaolinite, pseudomatrix, and pyrite. The mesogenetic alterations include cementation by quartz overgrowths, Fe-dolomite/ankerite, and illite, transformation of kaolinite to dickite, illitization of smectite, intergranular quartz dissolution, and stylolitization, and albitization of feldspar. The higher energy of deposition of the coarser-grained upper shoreface sandstones combined with less extensive chemical compaction and smaller amounts of quartz overgrowths account for their better primary reservoir quality compared to the finer-grained, middle-lower shoreface sandstones. The formation of kaolin in the upper and middle shoreface sandstones is attributed to a greater flux of meteoric water. More abundant quartz overgrowths in the middle and lower shoreface is attributed to a greater extent of stylolitization, which was promoted by more abundant illitic clays. This study demonstrated that linking the distribution of diagenetic alterations to depositional facies of shoreface sandstones leads to a better understanding of the impact of these alterations on the spatial and temporal variation in quality and heterogeneity of the reservoirs.

  18. Upper Permian (Guadalupian) coastal tidal flat and shelf lagoon deposits: outcrop model and subsurface examples of stratigraphic traps, Permian basin

    SciTech Connect

    Harris, P.M.; Ward, R.F.

    1986-05-01

    Over half a century of exploration and development drilling has shown that hydrocarbons reservoired in Upper Permian (Guadalupian) deposits of west Texas and southeastern New Mexico have accumulated at the contact between shelf-lagoon dolomites or siltstones and their updip coastal evaporite equivalents. Production from any of the Guadalupian shelf units similarly occurs from stacked reservoirs of dolomites or siltstones. Dolomites comprise shoaling cycles of deposition: intercrystalline and moldic porosities typify basal dolomudstones and dolowackestones as well as overlying dolopackstones, whereas capping dolomudstones may contain fenestral porosity but usually are tight and interlayered with anhydrite. Interparticle porosity occurs in siltstones that are interbedded with the dolomites. Reservoir development is more a problem of updip seal than porosity, as sediments other than lagoonal dolomites and siltstones are porous. Porous carbonate sands accumulated in a backreef position and the shelf margin reef and associated slope debris apron have developed porosity secondarily through solution, fracturing, and minor dolomitization. Hydrocarbons migrated from presumed basinal source rocks through the margin and backreef, and continued updip into shelf lagoon deposits that pinch out into tight anhydrite-cemented equivalents as well as interbedded evaporites of coastal tidal-flat origin.

  19. Recent and past Saharan dust deposition in the Carpathian Basin and its possible effects on interglacial soil formation

    NASA Astrophysics Data System (ADS)

    Varga, György

    2016-04-01

    Several hundred tons of windblown dust material are transported every year from Saharan dust source areas into direction of Europe, modifying important climatic and other environmental processes of distant areas. North African aerosols have been also identified several times a year in the Carpathian Basin, where under the influence of certain synoptic meteorological conditions Saharan dust accumulation can clearly be observed. Previous satellite based studies were suitable to estimate the frequency and magnitude of Saharan dust episodes in the investigation area, however, the assessment of North African dust deposition can be done with model simulations. In this study, calculations were made by using the data of BSC-DREAM8b (Barcelona Supercomputing Center's Dust REgional Atmospheric Model) v1.0 and v2.0 database. Simulation results of the BSC-DREAM8b v1.0 are available from 1 January 2000 to 31 December 2012, while the results of the updated v2.0 calculations are ready for the period between 1 January 2006 and 31 December 2014. BSC DREAM8b v1.0 model simulations for the period between 2000 and 2012 provided an annual mean of 0.0285 g/m2/y dry and 0.034 g/m2/y wet deposition values in the Carpathian Basin, which is equivalent to a total of 0.0636 g/m2/y. The updated v2.0 version for the period of 2006-2014 gave significantly larger values: 0.133 g/m2/y dry; 0.085 g/m2/y wet and 0.219 g/m2/y total annual dust deposition. By comparing the results of the overlapping period between 2006 and 2012 of the v1.0 and v2.0 simulations, the updated depositional scheme of the newer version provided ˜3.7-fold values in case of dry deposition and ˜1.9-fold increase in results of the wet deposition. Information available from individual events showed that the simulated wet and dry dust deposition rates are significantly underestimated. This is also suggested by previous model calculations which reported values between 5 and 10 g/m2/y for modern dust flux in the investigated area

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

    NASA Astrophysics Data System (ADS)

    Alçiçek, Hülya; Jiménez-Moreno, Gonzalo

    2013-06-01

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

  1. 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

  2. Effect of arena size on behaviour and mortality of the oriental cockroach Blatta orientalis in arenas with a cypermethrin deposit adjacent to harbourage access points.

    PubMed

    Le Patourel, G N

    1998-01-01

    Activity and survival of adult female Blatta orientalis was investigated using tagged cockroaches in periodically illuminated arenas (LD 12:12 h) with a harbourage at one end. The arenas were rectangular with a width of 50 cm and lengths up to 480 cm. A cypermethrin-treated plywood plate (50 x 11 cm) substrate across the harbourage access points caused cockroaches to be exposed to the insecticide deposit by tarsal contact as they entered or left the harbourage. The effects of varying arena length and cypermethrin concentration were tested at 28 degrees C. The LC50 following 3 days exposure ranged from 5.7 to 11.8 mg/m2 on the plywood plate for arena lengths of 60 to 480 cm, respectively; cypermethrin at 30 mg/m2 produced 100% knockdown of B. orientalis within one 12 h dark period. During darkness, active cockroaches spent most time close to the harbourage or around food and water stations, at the far end of the arena, and made frequent returns into the harbourage. For arena length 120 cm, the mean duration of contact with treated plates during the first hour of the dark period was significantly less than contact time on untreated plates, but during 12 h the cumulative contact times were not significantly different between treated and untreated plates. During the first 4 h of the dark period, mean cockroach numbers on the treated plate declined as arena length increased, but not as rapidly as the mean number/unit area over the rest of the arena. The arena design is considered suitable for comparative testing of fast-acting neuroactive insecticide deposits against cockroaches.

  3. Paleogeographic and paleotectonic setting of sedimentary basins in the Sevier thrust belt and hinterland, eastern Great Basin

    SciTech Connect

    Schmitt, J.G. . Dept. of Earth Sciences); Vandervoort, D.S. . Dept. of Geological Sciences); Suydam, J.D. . Dept. of Geology)

    1993-04-01

    The eastern Great Basin contains a sparse record of broadly distributed Cretaceous sedimentary rocks which record: evolution of intermontane basins during development of the Sevier (Sv)contractional orogen and incipient extensional collapse of the elevated Sv hinterland (east-central NV), and complex tectono-sedimentary interactions between frontal thrust belt structures and the western margin of the adjacent foreland basin. Palinspastic restoration of these strata and associated structures to pre-Tertiary extension positions reveals a clearer pictures of Cretaceous basin paleogeography and allows comparison with the Puna/Altiplano plateau and precordillera thrust belt of the Neogene Andean orogen. Two syntectonic stratal assemblages are present in east-central NV. Lower Cretaceous alluvial strata (Newark Canyon Fm) record basin development coeval with emergence of contractional structures in the Sv hinterland. Localized early Cretaceous basins were possibly piggyback immature; periods of open drainage to the to the east and south suggest connection with the nascent Sv foreland basin to the east (Cedar Mountain/Sanpete Fms) prior to major thrust loading in central Utah. Development of hinterland structures is almost recorded by Aptian-Albian foreland basin alluvial deposits in SW Utah (Dakota Fm) and southern Nevada (Willow Tank Fm). Upper Cretaceous to Eocene strata (Sheep Pass Fm) record inception of regionally abundant alluvial-lacustrine basins which developed in response to onset of latest Cretaceous extension and associated collapse of the Sv hinterland. Evolution of the structurally complex western margin of the Sv foreland basin is recorded in Cretaceous through Eocene strata deposited in: piggyback basins which were at times hydrologically connected to the adjacent foreland basins, and thrust-proximal portions of the foreland basin. These proximal areas are characterized by folding and faulting of basin fill and development of intrabasinal unconformities.

  4. High resolution magnetostratigraphy and deposition cycles in the Nihewan Basin (North China) and their significance for stone artifact dating

    NASA Astrophysics Data System (ADS)

    Huamei, Li; Xiaoqiang, Yang; Heller, Friedrich; Haitao, Li

    2008-03-01

    Three lacustrine sections in the Nihewan Basin, Xiaodukou, Donggutuo and Xiaochangliang (40.1-40.4°N; 114.6-114.7°E), were closely sampled for magnetostratigraphic and deposition cycle analysis. Rock magnetic investigations show that the characteristic remanent magnetization of the sediments is mainly carried by magnetite and hematite. The Xiaodukou sequence is one of the most complete sections in the basin and has recorded substantial parts of the Brunhes and Matuyama chrons back to the termination of the Olduvai subchron. Several subchrons within the Matuyama period have been documented such as the Jaramillo, the Cobb Mt. and others. The Matuyama/Brunhes boundary, the Jaramillo, as well as the Cobb Mountain events were observed also at Donggutuo. On the basis of grain size and susceptibility data and of field investigations, the sections are divided into two longer lasting lacustrine episodes with a fluvio-lacustrine deposit in between. They are structured by 15 high-frequency deposition sub-cycles. In each cycle, the grain size fines upwards, while magnetic susceptibility decreases. This behavior is due to cyclic water level change of the ancient lake Nihewan. At Xiaodukou, the variations of the 0.2 to 7.5 μm grain size fraction can be correlated with the marine oxygen isotope stages OIS 64-OIS 11. The grey-green clayey to silty Paleolithic stone artifact layers at Xiaochangliang and Donggutuo are located at depths of 55.4 m and 43-38.7 m, respectively. They were buried when the lake-level was rising. The artifact layers have been deposited around the Cobb Mountain event during the sedimentary sub-cycle 6 of the older lacustrine phase corresponding to OIS 35, 36. Thus in contrast to the results of other studies, the estimated age of the Xiaochangliang stone artifact layer does not exceed 1.26 Ma, while the Donggutuo stone artifact layers date back to 1.21-1.15 Ma. This age determination brings the Nihewan hominids in close relation to the findings of Homo

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

    NASA Astrophysics Data System (ADS)

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

    2001-10-01

    The Kathmandu Valley is an intermontane basin in the center of a large syncline of the Lesser Himalayas. The sedimentary basin fill comprises three units of Plio-Pleistocene to Holocene age. The study aimed at modeling the paleogeographic evolution of the basin, with emphasis on sedimentary series of fossil fuels and non-metallic deposits. The lithological setting of the basin and the tectonic framework were instrumental to basin subsidence. Alluvial through lacustrine sedimentation during incipient stages is a direct response to uplift in the hinge zone of the synclinorium. Axial parallel sediment dispersal gave way to fluviodeltaic sedimentation mainly from the limbs of the synclinorium. Ongoing compression and renewed uplift in the core zone of the synclinorium drove the uplift of a NW-SE running divide and a subdivision of the mono-lake into two basins. This ridge blocked the flow of transverse rivers and the northern subbasin became gradually choked. Ongoing uplift of the entire basin during the recent geological history caused a reorganization of the drainage pattern and triggered linear erosion in the southern mountain range. Step-by-step the remaining lacustrine basins disappeared. Fan aggradation coincide with cold dry or warm seasons, fluvial dissection and discharge increased during warmer and more humid periods. High lake levels exist during phases of increased humidity. The results of this basin analysis may be used predictively in the exploration for coal, natural gas, diatomaceous earths and quarrying for sand or clay. The gas potential is at its maximum in the lacustrine facies, sand and clay for construction purposes may be quarried economically from various fluvial and deltaic deposits. Diatomaceous earths predominantly accumulated in marginal parts of the lake and some landslide-dammed ponds. Lignitic brown coal can be mined together with combustible shales from poorly drained swamps.

  6. Deposition of selenium and other constituents in reservoir bottom sediment of the Solomon River Basin, north-central Kansas

    USGS Publications Warehouse

    Christensen, Victoria G.

    1999-01-01

    The Solomon River drains approximately 6,840 square miles of mainly agricultural land in north-central Kansas. The Bureau of Reclamation, U.S. Department of the Interior, has begun a Resource Management Assessment (RMA) of the Solomon River Basin to provide the necessary data for National Environmental Policy Act (NEPA) compliance before renewal of long-term water-service contracts with irrigation districts in the basin. In May 1998, the U.S. Geological Survey (USGS) collected bottom-sediment cores from Kirwin and Webster Reservoirs, which are not affected by Bureau irrigation, and Waconda Lake, which receives water from both Bureau and non-Bureau irrigated lands. The cores were analyzed for selected physical properties, total recoverable metals, nutrients, cesium-137, and total organic carbon. Spearman's rho correlations and Kendall's tau trend tests were done for sediment concentrations in cores from each reservoir. Selenium, arsenic, and strontium were the only constituents that showed an increasing trend in concentrations for core samples from more than one reservoir. Concentrations and trends for these three constituents were compared to information on historical irrigation to determine any causal effect. Increases in selenium, arsenic, and strontium concentrations can not be completely explained by Bureau irrigation. However, mean selenium, arsenic, and strontium concentrations in sediment from all three reservoirs may be related to total irrigated acres (Bureau and non-Bureau irrigation) in the basin. Selenium, arsenic, and strontium loads were calculated for Webster Reservoir to determine if annual loads deposited in the reservoir were increasing along with constituent concentrations. Background selenium, arsenic, and strontium loads in Webster Reservoir are significantly larger than post-background loads.

  7. Trend Analysis of Nitrogen Deposition to Baltic Sea and its sub basins

    NASA Astrophysics Data System (ADS)

    Semeena, V. S.; Jerzy, Bartnicki

    2009-04-01

    Since the beginning of last century, Baltic Sea has changed from a clear-water sea into a eutrophic marine environment. Eutrophication is the major problem in the Baltic Sea. Excessive nitrogen and phosphorus loads coming from land-based sources within and outside the catchment area of the bordering countries of the Baltic Sea are the main cause of the eutrophication in the sea. Even though a major part of nitrogen(75%) and phosphorus load(95%) enter the sea via rivers or as water-born discharges, 25% of the nitrogen load comes as atmospheric deposition. Numerical models are the best tools to measure atmospheric deposition into sea waters. We have used the latest version of the Unified EMEP model - which has been developed at the EMEP/MSC-W (Meteorological Synthesizing Centre - West of EMEP) for simulating atmospheric transport and deposition of acidifying and eutrophying compounds as well as photo-oxidants in Europe- to study the trends in atmospheric deposition of nitrogen into Baltic Sea for the period 1995-2006. The model domain covers Europe and the Atlantic Ocean. The model grid (of the size 170×133) has a horizontal resolution of 50 km at 60o N, which is consistent with the resolution of emission data reported to CLRTAP. Approximately 10 of these layers are placed below 2 km to obtain high resolution of the boundary layer which is of special importance to the long range transport of air pollution. EMEP model has been thouroughly validated (Fagerli et.al.[1], Simpson et.al.[2], Simpson et.al.[3] ) The contribution of deposition of nitrogen into Baltic Sea from each of the bordering countries of the Baltic Sea and the deposition trends for the period 1995-2006 has been analysed and the results will be presented. References: [1]. Fagerli H., Simpson D. and Aas W.: Model performance for sulphur and nitrogen compounds for the period 1980 to 2000. [In:] L. Tarraśon, (editor), Transboundary Acidification, Eutrophication and Ground Level Ozone in Europe. EMEP

  8. Palaeoenvironment of mid- to late Holocene loess deposit of the southern margin of the Tarim Basin, NW China

    NASA Astrophysics Data System (ADS)

    Zihua, Tang; Guijin, Mu; Dongmei, Chen

    2009-10-01

    Holocene environmental history in the Tarim Basin and the Taklimakan Desert is known mainly from isolated eolian and lacustrine deposits and remain puzzling. Here we present an adequately preserved loess section, covering the past 5000 years, at a highland (2,850 m a.s.l) on the northern slope of Kunlun Mountains. Pollen preserved in the section reveal a drying trend with significant moisture fluctuations around 3000-2600 cal yr BP and 1800 cal yr BP at the study site. Comparing the pollen, grain size from the same section provides a different scene occurred in the Tarim basin and the Taklimakan desert. Comparison of grain size to A/C ration of pollen suggests that active sand southward shifting in south margin of the desert is coincident with increasing moisture condition at the section locality, implying a casual link. This moisture pattern occurred at the upper and lower elevation of the slope is best explained by the vertical variation of local precipitation along the slope.

  9. Ground Penetrating Radar Investigation of Sinter Deposits at Old Faithful Geyser and Immediately Adjacent Hydrothermal Features, Yellowstone National Park, Wyoming, USA

    NASA Astrophysics Data System (ADS)

    Foley, D.; Lynne, B. Y.; Jaworowski, C.; Heasler, H.; Smith, G.; Smith, I.

    2015-12-01

    Ground Penetrating Radar (GPR) was used to evaluate the characteristics of the shallow subsurface siliceous sinter deposits around Old Faithful Geyser. Zones of fractures, areas of subsurface alteration and pre-eruption hydrologic changes at Old Faithful Geyser and surrounding hydrothermal mounds were observed. Despite being viewed directly by about 3,000,000 people a year, shallow subsurface geologic and hydrologic conditions on and near Old Faithful Geyser are poorly characterized. GPR transects of 5754 ft (1754m) show strong horizontal to sub-horizontal reflections, which are interpreted as 2.5 to 4.5 meters of sinter. Some discontinuities in reflections are interpreted as fractures in the sinter, some of which line up with known hydrothermal features and some of which have little to no surface expression. Zones with moderate and weak amplitude reflections are interpreted as sinter that has been hydrothermally altered. Temporal changes from stronger to weaker reflections are correlated with the eruption cycle of Old Faithful Geyser, and are interpreted as post-eruption draining of shallow fractures, followed by pre-eruption fracture filling with liquid or vapor thermal fluids.

  10. Diagenetic overprint of original depositional architecture in a shallow water carbonate reservoir, Permian Basin, Texas

    SciTech Connect

    Ruppel, S.C.; Lucia, F.J.

    1996-12-31

    Permian shallow-water carbonate reservoirs are highly heterogeneous because of complex variations in depositional facies produced by high-frequency sea level rise and fall. Accordingly, establishment of a cycle stratigraphic framework is fundamental to defining reservoir heterogeneity. Because nearly all of these reservoirs have experienced multiple episodes of dolomitization and sulfate emplacement, however, permeability is a n of diagenetic overprint. The extent to which diagenesis can affect permeability development is dramatically displayed in the Grayburg Formation (middle Permian) at South Cowden field, Weit Texas. Three scales of cyclicity contribute to original depositional facies heterogeneity in the Grayburg; high-frequency cycles, averaging 3 meters in thickness, constitute the fundamental architectural element in the main reservoir interval. Despite original depositional heterogeneity due to this cyclicity, however, permeability development is substantially the result of two diagenetic events: (1) dolomite diagenesis in vertically burrowed wackestones and packstones and (2) late alteration and removal of anhydrite. Dolomite diagenesis in vertically burrowed wackestones and packstones has produced irregular vertical zones of higher permeability in mud-dominated bases of high-frequency cycles in leeward ramp-crest highstand successions. Because dolomite diagenesis is concentrated in burrowed highstand successions, the distribution of resultant permeability trends is partly constrained by patterns of longterm accommodation and high frequency cyclicity. Anhydrite diagenesis, which is characterized by conversion to gypsum or by complete removal of sulfate, is developed along basinward margins of the field and cross cuts original depositional framework.

  11. Diagenetic overprint of original depositional architecture in a shallow water carbonate reservoir, Permian Basin, Texas

    SciTech Connect

    Ruppel, S.C.; Lucia, F.J. )

    1996-01-01

    Permian shallow-water carbonate reservoirs are highly heterogeneous because of complex variations in depositional facies produced by high-frequency sea level rise and fall. Accordingly, establishment of a cycle stratigraphic framework is fundamental to defining reservoir heterogeneity. Because nearly all of these reservoirs have experienced multiple episodes of dolomitization and sulfate emplacement, however, permeability is a n of diagenetic overprint. The extent to which diagenesis can affect permeability development is dramatically displayed in the Grayburg Formation (middle Permian) at South Cowden field, Weit Texas. Three scales of cyclicity contribute to original depositional facies heterogeneity in the Grayburg; high-frequency cycles, averaging 3 meters in thickness, constitute the fundamental architectural element in the main reservoir interval. Despite original depositional heterogeneity due to this cyclicity, however, permeability development is substantially the result of two diagenetic events: (1) dolomite diagenesis in vertically burrowed wackestones and packstones and (2) late alteration and removal of anhydrite. Dolomite diagenesis in vertically burrowed wackestones and packstones has produced irregular vertical zones of higher permeability in mud-dominated bases of high-frequency cycles in leeward ramp-crest highstand successions. Because dolomite diagenesis is concentrated in burrowed highstand successions, the distribution of resultant permeability trends is partly constrained by patterns of longterm accommodation and high frequency cyclicity. Anhydrite diagenesis, which is characterized by conversion to gypsum or by complete removal of sulfate, is developed along basinward margins of the field and cross cuts original depositional framework.

  12. Hydrogeologic Framework and Ground Water in Basin-Fill Deposits of the Diamond Valley Flow System, Central Nevada

    USGS Publications Warehouse

    Tumbusch, Mary L.; Plume, Russell W.

    2006-01-01

    The Diamond Valley flow system, an area of about 3,120 square miles in central Nevada, consists of five hydrographic areas: Monitor, Antelope, Kobeh, and Diamond Valleys and Stevens Basin. Although these five areas are in a remote part of Nevada, local government officials and citizens are concerned that the water resources of the flow system eventually could be further developed for irrigation or mining purposes or potentially for municipal use outside the study area. In order to better understand the flow system, the U.S. Geological Survey in cooperation with Eureka, Lander, and Nye Counties and the Nevada Division of Water Resources, is conducting a multi-phase study of the flow system. The principal aquifers of the Diamond Valley flow system are in basin-fill deposits that occupy structural basins comprised of carbonate rocks, siliciclastic sedimentary rocks, igneous intrusive rocks, and volcanic rocks. Carbonate rocks also function as aquifers, but their extent and interconnections with basin-fill aquifers are poorly understood. Ground-water flow in southern Monitor Valley is from the valley margins toward the valley axis and then northward to a large area of discharge by evapotranspiration (ET) that is formed south of a group of unnamed hills near the center of the valley. Ground-water flow from northern Monitor Valley, Antelope Valley, and northern and western parts of Kobeh Valley converges to an area of ground-water discharge by ET in central and eastern Kobeh Valley. Prior to irrigation development in the 1960s, ground-water flow in Diamond Valley was from valley margins toward the valley axis and then northward to a large discharge area at the north end of the valley. Stevens Basin is a small upland basin with internal drainage and is not connected with other parts of the flow system. After 40 years of irrigation pumping, a large area of ground-water decline has developed in southern Diamond Valley around the irrigated area. In this part of Diamond

  13. Lithostratigraphic description, sedimentological characteristics and depositional environments of rocks penetrated by Illela borehole, Sokoto Basin, NW Nigeria: A connection between Gulf of Guinea Basins

    NASA Astrophysics Data System (ADS)

    Toyin, A.; Adekeye, O. A.; Bale, R. B.; Sanni, Z. J.; Jimoh, O. A.

    2016-09-01

    The basal unit of the succession in the Illela borehole belongs to the Dange Formation comprising thick calcareous and variably coloured dark-greyish shale of 36.30 m thick which is overlain by a 31.44 m thick limestone of Kalambaina Formation with 1.7 m thick shaly-limestone inclusive. The uppermost part of the section belongs to the Gwandu Formation which has intercalation of silty-clay, muddy siltstones with well lithified ironstone capping the borehole section. The limestone/carbonate microfacie as deduced from their salient lithologic, sedimentologic and paleontologic features are comparable to standard microfacie (SMF) types 9 and 10, i.e. bioclastic wackestone/bioclastic micrite and packstone-wackestone respectively. Diagenetically, syndepositional and early diagenesis have taken place particularly cementation and replacement in the carbonate rocks and these have greatly affected the reservoir potential negatively. The matrix/grain relationships indicate a shallow marine environment of deposition. The borehole section is delineated into upper foraminifera and lower ostracod biostratigraphic units as no formal biostratigraphic zonation could be attempted due to low diversity of both benthic foraminifera, marine ostracods and the absence of planktonic foraminifera. The similarity of the ostracod assemblages between this study area, Illela borehole, West Africa, North Africa (Libya), Mali and Niger Republic) and South-Western Nigeria (West Africa) suggests that a marine connection exists between the Gulf of Guinea and the Sokoto Basin via the area occupied by the River Niger during the Paleocene.

  14. A high-resolution angiosperm pollen reference record covering Albian mid-latitude coastal deposits (Lusitanian Basin, Portugal)

    NASA Astrophysics Data System (ADS)

    Horikx, Maurits; Dinis, Jorge L.; Heimhofer, Ulrich

    2013-04-01

    The Lusitanian Basin in Portugal is one of the most important areas to investigate the rise and radiation of early angiosperms. Here, important micro-, macro- and mesofossil remains including pollen, reproductive organs, fruits and seeds have been found. In this study, a high-resolution Early to Late Albian pollen record from a thick (~160m) coastal succession in the Lusitanian Basin containing mixed carbonate-siliciclastic near-shore deposits is generated. The outcrop is located near the town of Ericeira (São Julião) and exhibits some important new features compared to existing records from the Lusitanian basin. The comparatively proximal depositional setting and high sedimentation rate of the São Julião outcrop is well suited for high-resolution palynological sampling compared to previously studied, more distal outcrops. In addition, the succession covers almost the entire Albian including a thick interval representing Late Albian strata. Dating of the succession was obtained using dinoflagellate cyst biostratigraphy, bulk C-isotope analysis and strontium isotope analysis of low-Mg oysters and rudist shells. The high-resolution pollen record shows a distinct radiation pattern of early angiosperm pollen as well as significant changes in the accompanying palynoflora. During most of the section gymnosperm pollen types such as Classopollis spp., Inaperturopollenites spp. and Exesipollenites spp. are dominant. Angiosperm pollen abundances do not exceed 20%, although angiosperms increase slightly from the Early Albian onwards. Monoaperturate grains of magnoliid or monocot affinity remain the most dominant angiosperm pollen type, both in abundances and diversity. Tricolpate and zonoaperturate pollen grains are also present. In addition, the occurrence of several odd-shaped Dichastopollenites-type pollen types is intriguing. The palynological results indicate a warm and dry climate during most of the Albian, although a rise in the spores over pollen ratio in the

  15. Geochemistry of vanadium in an epigenetic, sandstone-hosted vanadium- uranium deposit, Henry Basin, Utah

    USGS Publications Warehouse

    Wanty, R.B.; Goldhaber, M.B.; Northrop, H.R.

    1990-01-01

    The epigenetic Tony M vanadium-uranium orebody in south-central Utah is hosted in fluvial sandstones of the Morrison Formation (Upper Jurassic). Measurements of the relative amounts of V+3 and V +4 in ore minerals show that V+3 is more abundant. Thermodynamic calculations show that vanadium was more likely transported to the site of mineralization as V+4. The ore formed as V+4 was reduced by hydrogen sulfide, followed by hydrolysis and precipitation of V+3 in oxide minerals or chlorite. Uranium was transported as uranyl ion (U+6), or some complex thereof, and reduced by hydrogen sulfide, forming coffinite. Detrital organic matter in the rocks served as the carbon source for sulfate-reducing bacteria. Vanadium most likely was derived from the dissolution of iron-titanium oxides. Uranium probably was derived from the overlying Brushy Basin Member of the Morrison Formation. Previous studies have shown that the ore formed at the density-stratified interface between a basinal brine and dilute meteoric water. The mineralization processes described above occurred within the mixing zone between these two fluids. -from Authors

  16. Depositional facies of hydrocarbon reservoirs of upper Cherokee Group, Anadarko basin

    SciTech Connect

    Puckette, J.O.; Al-Shaieb, Z. )

    1989-08-01

    The Desmoinesian upper Cherokee Group sequence in the Anadarko basin is the subsurface equivalent of the Cabaniss Group of eastern Oklahoma. This sequence includes the Pink limestone, Skinner sandstone, Verdigris limestone, and Prue sandstone intervals. The upper Skinner sandstone, which has not been well documented, is an important hydrocarbon-producing reservoir in the Anadarko basin. The Skinner sandstone is represented by channel, delta-front-prodelta, and shallow marine facies. Channel facies consist of a primary elongate trend extending 40 mi southeast-northwest across Custer and Roger Mills Counties, Oklahoma. Several small secondary channels trending northeast-southwest were also observed. Active channel-fill sequences in the primary trend exceed 100 ft in thickness and represent the major producing reservoir of the upper Skinner sandstone. Delta-front-prodelta sequences are dominated by shale and interbedded sandstone-shale units. Shallow marine facies consist of massive coarsening-upward units that reach 300 ft in thickness. This facies belt is broad and slightly elongated, approximately 12 mi wide by 20 mi long, and trends northeast-southwest somewhat normal to channel facies orientation. Lithologically, the upper Skinner channel sandstone is feldspathic litharenite with abundant feldspar and quartz overgrowth. Both primary and secondary porosity were observed in the upper Skinner sandstone. Secondary porosity evolved mainly from dissolution of feldspar and lithic fragments. However, extensive cementation in the shallow marine facies has reduced porosity to negligible amounts and consequently reduced reservoir quality.

  17. Climatic controls on arid continental basin margin systems

    NASA Astrophysics Data System (ADS)

    Gough, Amy; Clarke, Stuart; Richards, Philip; Milodowski, Antoni

    2016-04-01

    models suggest that the deposits of the Brockram alluvial fans have the potential to contain numerous preferential flow zones. Where these flow zones are adjacent to the unique deposits of the zone of interaction it affects basin-scale fluid flow by: 1) interconnecting decent reservoirs in the distal extent of the basin; 2) creating flow pathways away from these reservoirs; 3) introducing secondary baffles into the system; and, 4) creating a bypass to charge these distal reservoirs.

  18. 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.

  19. The Topography and Basin Deposits of the Equatorial Highlands: A MGS-Viking Synergistic Study

    NASA Astrophysics Data System (ADS)

    Moore, J. M.; Howard, A. D.; Schenk, P. M.

    1999-09-01

    We are using Digital Terrain Models (DTM) to evaluate the sequence and extent of various landform-modifying processes that have shaped the martian equatorial highlands using models that simulates these processes on a three-dimensional synthetic landscape. This modeling emulates the following processes: (1) cratering; (2) fluvial erosion and sedimentation; (3) weathering and mass wasting; (4) aeolian erosion and deposition; (5) groundwater flow and groundwater sapping; and (6) volcanic deposition of different emplacement modes. The models have been successfully used to predict the evolution of terrestrial landscapes. The models provide explicit simulations of landform development and thusly predict the topographic evolution of the surface and final landscape form. We generate combined Viking-MOLA DTMs, so that we have absolute regional and high resolution topographic information. With our DTMs we are able to much more realistically evaluate the evolution of specific locations within the cratered uplands of Mars than would be possible from either data set alone. Results of this analysis have direct import to Mars Surveyor Program landing site selection and science. We have selected three areas for our initial studies: (1) the south edge of the "hematite" deposit detected by TES and observed to be bordered by scarps and knobs exhibiting layers in Viking and MOC SPO images located at 2 degS, 4 degW; (2) a typical example of equatorial cratered highlands at 2 degN, 240.5 degW; and (3) a site at 5 degS and 264 degW just south of the Isidis rim that is heavily dissected by channels. These regions were optimally imaged by Viking for the generation of DTMs, lie within the Mars 2001 landing constraints, and are potential locations for fluvial or lacustrine deposits. Our initial analysis of the later sites indicates that fluvial erosion for large solitary channels probably took the form of sapping, whereas denser networks of small channels may have formed at least in part

  20. Detection and Extent of Ancient, Buried Mare Deposits in South Pole-Aitken Basin (SPA):Implications for Robotic Sampling

    NASA Astrophysics Data System (ADS)

    Petro, N. E.; Jolliff, B. L.; Gaddis, L. R.; Pieters, C. M.

    2010-12-01

    The origin of the large mafic anomaly associated with the interior of the South Pole-Aitken Basin has been inferred to be largely the result of iron-rich lower crustal/upper mantle material exposed at the surface and/or a combination of ancient mare basalts covered by younger crater/basin ejecta (cryptomare) interspersed with younger basalts [1-3]. However, the relative influence of either source is poorly constrained, due in part to the unknown abundance of cryptomare within SPA. Early geologic mapping of the interior of SPA identified several plains units, thought to represent basin ejecta deposits [4, 5]. Newer remotely sensed VIS-NIR wavelength data suggested the presence of more extensive deposits of ancient, buried basalts [2, 3, 6]. Mare basalts, when mantled by non-local, low-FeO material may appear to be non-mare plains units [7, 8]. Within SPA, because the regional basement material is inherently enriched in FeO, the mantling material imparts a dark, FeO-enriched, signature. In a survey of rock types within SPA, Pieters et al. [3] identified such a plains unit south of the Apollo Basin with a surface that is both dark and that contains an FeO-rich spectral signature. However, several small craters in the plains unit expose underlying basaltic materials or cryptomaria in this extensive (>75,000 km2), ancient (~3.89 Ga) unit [6, 9]. The positive identification and characterization of cryptomaria within SPA are facilitated by high-spatial and spectral resolution data from recent orbital missions (e.g., Kaguya, Chandrayaan-1, LRO). Hyperspectral data from the Moon Mineralogy Mapper and Multiband Imager for SPA show the presence of two primary mafic materials; a high-Ca pyroxene (gabbroic) signature is pervasive across the center of the basin and a noritic signature is present across the rest of SPA. High spatial resolution (10-0.5 m) images from the Kaguya Terrain Camera and LRO Narrow Angle Camera facilitate surface age dating and morphologic assessment of

  1. Holocene climatic events recorded in palaeoflood slackwater deposits along the middle Yiluohe River valley, middle Yellow River basin, China

    NASA Astrophysics Data System (ADS)

    Zhao, Xueru; Huang, Chun Chang; Pang, Jiangli; Zha, Xiaochun; Guo, Yongqiang; Hu, Guiming

    2016-06-01

    Palaeohydrological investigations were carried out in the middle reaches of the Yiluohe River, a major tributary in the lower-middle Yellow River basin. Typical palaeoflood slackwater deposits (SWDs) were identified in the Holocene pedostratigraphy on the cliffy river banks. Analytical results, including magnetic susceptibility and grain-size distribution data, indicated that these SWDs were deposited from the suspended sediment load in flood water. These SWDs are different from eolian loess, soils and aeolian sands in the riverbank profile. They recorded several episodes of extraordinary palaeoflood events. In the Longmenxia reaches of the Yihe River valley, these flood events were dated at 3100-3000 a, 1800-1700 a, 770-610 a, and 420-340 a using the optically stimulated luminescence method in combination with the pedostratigraphic correlations. In the Longhutan reaches of the Luohe River valley, the palaeoflood events were dated at 1975-1466 a, i.e., from the Han to Wei dynasties (AD 25-534), during which the capital city on the river banks was flooded many times, as recorded in the literature. These extraordinary flood events are well correlated chronologically with the known Holocene climatic events that occurred in the Northern Hemisphere. Thus, the monsoonal climate was highly variable with both floods and droughts occurring frequently during these episodes. These results are important for understanding the response of river systems in eastern Asia to global changes.

  2. Liquefaction and fluidization structures in Messinian storm deposits (Bajo Segura Basin, Betic Cordillera, southern Spain)

    NASA Astrophysics Data System (ADS)

    Alfaro, P.; Delgado, J.; Estévez, A.; Molina, J. M.; Moretti, M.; Soria, J. M.

    2002-05-01

    Synsedimentary deformation structures are recognized in Upper Miocene deposits of the eastern Betic Cordillera (SE Spain). A singular stratigraphic section in these deposits shows several levels with soft-sediment deformation structures (load casts, ball-and-pillows and pipes) induced by liquidization (liquefaction and/or fluidization) of sandy sediments. The morphologic analysis of these structures reveals a liquidized sediment thickness ranging from 0.1 to 1.5 m. Although they have been previously interpreted as a result of seismic shocks, their origin was most likely related to the action of storm waves as the structures are always associated with tempestites. Facies analysis, geometrical features of the deformed beds and appraisal of geotechnical properties for shelf and coastal sediments allow the soft-sediment deformation structures to be interpreted as a result of the cyclic effect of storm waves on unconsolidated sediments, and excludes other processes such as overloading, tsunamis or the impact of breaking waves.

  3. Experimental studies of supercritical bedforms applied to coarse-grained turbidite deposits of the Tabernas Basin (SE Spain, late Miocene)

    NASA Astrophysics Data System (ADS)

    Cartigny, Matthieu; Postma, George; Kleverlaan, Kick

    2014-05-01

    Modern submarine canyon floors are often covered with bedform patterns linked to supercritical turbidity currents, while recognition of sedimentary structures associated with such bedforms in outcrops are rare. On the basis of experimental work on bed morphodynamics and flow structure of high-density turbidity currents, a 3-dimensional bedform stability diagram and related sedimentary facies diagram have been constructed. To allow scaling of this diagram to natural flows, four non-dimensional parameters are used: 1) densimetric Froude number, 2) modified mobility parameter, 3) dimensionless grain size and 4) basal sediment concentration. Each bedform and basal sediment concentration is then linked to a characteristic facies type. Numerical and theoretical models from the literature and observations from modern turbidite depositional systems are used to estimate characteristic sizes of the bedforms for different flow types. The model is applied to the turbidite fan systems of the Tabernas Basin (SE Spain, late Miocene) and discussed along existing classical models of high density turbidity current deposits. It is concluded that the vertical sequence of supercritical bedforms have been described in these models, yet to date have never been recognized as bedforms in outcrop, presumably because of their large size that easily exceeds the dimensions of commonly available outcrop. On the basis both experimental work and outcrop studies in the Tabernas Basin (SE Spain) a conceptual three-dimensional bedform diagram for recognition of cyclic steps in outcrop is constructed. Experimental data indicates that depositional processes on the stoss-side of a cyclic step are controlled by hydraulic jump, which temporarily stalls the flow and by subsequent waxing of the flow up to supercritical again. The hydraulic jump produces large scours with soft sediment deformation (flames) preserved in Bouma Ta, while near horizontal, massive to stratified top-cut-out turbidite beds are

  4. Quaternary deposits in southwestern Afghanistan

    USGS Publications Warehouse

    Smith, G.I.

    1974-01-01

    Geologic evidence in the closed Seistan Basin of southwestern Afghanistan and adjacent parts of Iran and Pakistan indicates that a lake as much as 65,000 sq km in size occupied this closed depression during Pleistocene time. The deposits consist mostly of lacustrine silt and clay and have a maximum observed thickness of about 250 m. A layer of alluvial gravels overlies the sequence. The deposits are probably early or middle Pleistocene in age; they are old enough to have sustained nearly 300 m of erosion over large areas but are not faulted or detectably folded in the central part of the basin although they are upwarped along the west edge of the basin. Sand dunes cover extensive areas of the basin. Dune orientation shows that the strong surface winds enter the basin blowing toward the south-southeast and then are deflected to the east, apparently as a response to mountains bordering the basin on its south side. The Gawdezereh, a large deflation depression, may be a result of an augmented excavation ability of winds that oc urs where turbulence is created along a zone of deflection. ?? 1974.

  5. 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.

  6. Structural evolution and petroleum productivity of the Baltic basin

    SciTech Connect

    Ulmishek, G.F. )

    1991-08-01

    The Baltic basin is an oval depression located in the western part of the Russian craton; it occupies the eastern Baltic Sea and adjacent onshore areas. The basin contains more than 5,000 m of sedimentary rocks ranging from latest Proterozoic to Tertiary in age. These rocks consist of four tectonostratigraphic sequences deposited during major tectonic episodes of basin evolution. Principal unconformities separate the sequences. The basin is underlain by a rift probably filled with Upper Proterozoic rocks. Vendian and Lower Cambrian rocks (Baikalian sequence) form two northeast-trending depressions. The principal stage of the basin development was during deposition of a thick Middle Cambrian-Lower Devonian (Caledonian) sequence. This stage was terminated by the most intense deformations in the basin history. The Middle Devonian-Carboniferous (Hercynian) and Permian-Tertiary (Kimmerian-Alpine) tectonic and depositional cycles only slightly modified the basin geometry and left intact the main structural framework of underlying rocks. The petroleum productivity of the basin is related to the Caledonian tectonostratigraphic sequence that contains both source rocks and reservoirs. However, maturation of source rocks, migration of oil, and formation of fields took place mostly during deposition of the Hercynian sequence.

  7. Diagenesis of Paleozoic playa-lake and ephemeral-stream deposits from the Pimenta Bueno Formation, Siluro-Devonian (?) of the Parecis Basin, central Brazil

    NASA Astrophysics Data System (ADS)

    Goldberg, K.; Morad, S.; Al-Aasm, I. S.; De Ros, L. F.

    2011-07-01

    The Parecis Basin is a large intracratonic rift located in central Brazil and filled with Paleozoic carbonate, evaporite and siliciclastic sediments. The occurrence of gas seeps has recently attracted significant exploration interest by the Brazilian petroleum agency and by Petrobras. The continuously cored PB-01-RO well provided the first opportunity to study the depositional environments, diagenetic evolution and hydrocarbon potential of the largely unknown sedimentary successions of the Parecis Basin. The cored lithologies, belonging to the Siluro-Devonian (?) Pimenta Bueno Formation, are interpreted as deposited in playa-lake and ephemeral-stream environments. The deposits display a strong facies control on the diagenetic mineral assemblages and evolution. Diagenetic minerals in the ephemeral-stream deposits include eogenetic hematite and smectitic clay coats and quartz cement, and the mesogenetic process includes precipitation of sulfates (anhydrite and barite) and carbonates (calcite, dolomite and kutnahorite-ankerite-huntite), followed by partial dissolution of these carbonates and sulfates, and of feldspar grains. Telogenetic processes include the precipitation of hematite and kaolinite within secondary pores, and the replacement of anhydrite by gypsum. A second burial phase and mesodiagenesis is indicated by the precipitation of discrete K-feldspar crystals within moldic pores after dissolved feldspars, and by the illitization of etched, telogenetic kaolinite. The playa-lake deposits show early diagenetic dolomitization of lime mud, precipitation of anhydrite nodules and extensive silicification. The anhydrite nodules were replaced by gypsum and chalcedony during telodiagenesis. Potential source rocks are locally represented by organic shales. The fluvial sandstones show fair reservoir quality and limited compaction, as indicated by their intergranular volume, suggesting that the succession has undergone moderate burial. Potential seals for hydrocarbon

  8. The uniform K distribution of the mare deposits in the Orientale Basin: Insights from Chang'E-2 gamma-ray spectrometer

    NASA Astrophysics Data System (ADS)

    Zhu, Meng-Hua; Chang, Jin; Xie, Minggang; Fritz, Jörg; Fernandes, Vera A.; Ip, Wing-Huen; Ma, Tao; Xu, Aoao

    2015-05-01

    The composition of mare basalt units in the Orientale Basin are investigated by using the potassium (K) map derived from Chang'E-2 gamma-ray spectrometer (CE-2 GRS) and FeO map derived from Clementine UV-Vis data set. Together with crater retention ages of the mare basalts from literature data, we aim to investigate possible magma sources underneath the Orientale Basin and their chemical evolution over time. Analyses of the chemical composition of the resurfaced mare basalts together with the reported eruption ages suggest a unique magma generating process for the resurfaced mare deposits. The early mare basalts in the central Mare Orientale and the later resurfaced mare deposits probably derived from magma generated by heat release due to high radioactive element concentrations. Based on forward modeling, the similar K abundances observed in the small mare deposits of the SW polygon area, Lacus Veris, and Lacus Autumni and those in the central Mare Orientale imply the same heat source for these lava eruptions. The chemical similarities (e.g., K, FeO, and TiO2) of these regions suggest that mare basalts within the Orientale Basin are a result of multiple eruptions from a relatively homogeneous source underneath the Basin.

  9. Seismic, magnetic, and geotechnical properties of a landslide and clinker deposits, Powder River basin, Wyoming and Montana

    USGS Publications Warehouse

    Miller, C.H.

    1979-01-01

    Exploitation of vast coal and other resources in the Powder River Basin has caused recent, rapid increases in population and in commercial and residential development and has prompted land utilization studies. Two aspects of land utilization were studied for this report: (1) the seismic and geotechnical properties of a landslide and (2) the seismic, magnetic, and geotechnical properties of clinker deposits. (1) The landslide seismic survey revealed two layers in the slide area. The upper (low-velocity) layer is a relatively weak mantle of colluvium and unconsolidated and weathered bedrock that ranges in thickness from 3.0 to 7.5 m and has an average seismic velocity of about 390 m/s. It overlies high-velocity, relatively strong sedimentary bedrock that has velocities greater than about 1330 m/s. The low-velocity layer is also present at the other eight seismic refraction sites in the basin; a similar layer has also been reported in the Soviet Union in a landslide area over similar bedrock. The buried contact of the low- and high-velocity layers is relatively smooth and is nearly parallel with the restored topographic surface. There is no indication that any of the high-velocity layer (bedrock) has been displaced or removed. The seismic data also show that the shear modulus of the low-velocity layer is only about one-tenth that of the high-velocity layer and the shear strength (at failure) is only about one-thirtieth. Much of the slide failure is clearly in the shear mode, and failure is, therefore, concluded to be confined to the low-velocity layer. The major immediate factor contributing to landslide failure is apparently the addition of moisture to the low-velocity layer. The study implies that the low-velocity layer can be defined over some of the basin by seismic surveys and that they can help predict or delineate potential slides. Preventative actions that could then be taken include avoidance, dewatering, prevention of saturation, buttressing the toe, and

  10. Boron-bearing potassium feldspar of authigenic origin in closed-basin deposits

    USGS Publications Warehouse

    Sheppard, Richard A.; Gude, Arthur J.

    1973-01-01

    Silicic vitric tuffs in saline, alkaline lacustrine deposits are commonly altered to a variety of zeolites and potassium feldspar. The tuffs generally show a lateral gradation, in a basinward direction, of fresh glass to zeolites and then to potassium feldspar. Zeolites were formed early in diagenesis by reaction of the glass with the interstitial water. The feldspar, however, was formed later by reaction of the zeolites with interstitial water, and its formation can be correlated with water of relatively high salinity and alkalinity. Semiquantitative spectrographic analyses for boron in the zeolites and potassium feldspar show that most of the boron resides in the relatively late feldspar. The boron content of the zeolites is commonly less than 100 ppm, whereas the boron content of the potassium feldspar is commonly greater than 1,000 ppm. Boron apparently substitutes for aluminum in the feldspar structure and causes distortion of the monoclinic unit cell such that the b and c dimensions are shortened. These boron-bearing potassium feldspars having anomalous cell parameters seem unique to saline,alkaline lacustrine deposits and could serve as a prospecting aid for locating buried saline minerals.

  11. Genesis of the tabular-type vanadium-uranium deposits of the Henry Basin, Utah

    USGS Publications Warehouse

    Northrop, H.R.; Goldhaber, M.B.

    1990-01-01

    Tabular-type vanadium-uranium deposits occur in fluvial sandstones of the Salt Wash Member of the Morrison Formation of Late Jurassic age The mineralized intervals and the weakly mineralized lateral extensions are bounded both above and below by zones rich in dolomite cement. Carbon isotope values of dolomite cements indicate that at least two sources of carbon existed. One source appears to be the same as that which formed the bedded carbonates in the evaporites in the Tidwell Member of the Morrison Formation stratigraphically below the mineralized interval. The second carbon source is typical of terrestrially deposited carbonates generally associated with meteoric water-dominated environments. Oxygen isotope values of these dolomites show the same trend of isotopically light values above the mineralized interval and isotopically heavier values in and below that interval; they indicate that two isotopically distinct fluids were involved in the mineralizing process. Some aspects of the origin of gangue and ore phases are explainable on the basis of processes which occurred solely within the saline fluid, but key aspects of ore genesis involved the interaction of the saline and meteoric waters. It is postulated that the solution interface migrated vertically within the stratigraphic section. -from Authors

  12. 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.

  13. Fish body burden: An index of atmospheric deposition of contaminants in the Great Lakes Basin

    SciTech Connect

    Swain, W.R.

    1994-12-31

    Since the mid-1970`s, contaminant monitoring in the flesh of fish from Siskiwit Lake, a remote lake on Isle Royale (Lake Superior), has served as an index of atmospheric transport to the upper Great Lakes basin. Using contemporary analytic methodologies, analysis of historic archived samples from this lake when compared with 1993 collections indicate dramatic changes in contaminant burdens for many compounds of concern. For example, dieldrin, the alpha isomer of BHC, and DDT/DDD/DDE all increased between 1974--76 and 1980, but had decreased markedly by 1993. Chlordane (analyzed as technical, alpha, and gamma chlordane), and total PCBs demonstrated a steady decline from the mid 1 970`s to the present. The pattern for these compounds remains similar in both the contaminant burden data, and when the values are adjusted for fish lipid content. Congener specific analysis for toxic coplanar PCBs indicate that ten non or mono-ortho PCBs predominate in fish, six of which were observed in a remarkably consistent pattern and percentage composition, i.e., PCB 118 > 105 > 156 > 189 > 77. Polychlorinated dioxin (PCDD) and debenzofuran (PCDF) TEQ values also declined by half between 1980 and 1993. However, fish from a comparative atmospherically driven system, Crystal Lake, had PCDD and PCDF TEQs an order of magnitude below those of Isle Royale fish. These differences, along with the pattern of chlorination observed, suggest the possibility of relatively more local influences than the long range atmospheric transport which was originally implicated.

  14. Mining conditions and deposition in the Amburgy (Westphalian B) coal, Breathitt Group, central Appalachian basin

    SciTech Connect

    Greb, S.F.; Eble, C.F.; Hower, J.C.; Phillips, T.L.

    1996-09-01

    Carbonate concretions called clay balls are rare in the Central Appalachian Basin, but were found in the Amburgy coal overlain by the Kendrick Shale Member. In the study area, the Amburgy coal is 0.7 to 0.9 meters thick, moderate to high in sulfur content, moderate to high in ash yield, and mostly bright clarain, except at the top near the area of coal balls, where durain of limited extent occurs. The coal is co-dominated by lycopod and cordaites; tree spores, with subordinate Calamites. The local durain layer is dominated by Densosporites, produced by the shrubby lycopod Ompbalophloios. Coal balls were encountered where the durain is immediately overlain by a coquinoid hash of broken and whole marine fossils, along a trend of coal thinning. The coal balls contain permineralized cordaites, lycopods, calamites, and ferns. The Amburgy coal accumulated as a succession of planar mires. Local splits in the seam are common, indicating contemporaneous clastic influx. The abundance of Cordaites may indicate brackish mire waters related to a coastal position and initial eustatic rise of the marginal Kendrick seas. Near the end of the Amburgy mires, the high ash-Omphalopbloios association is interpreted as a local area that was being drowned by the Kendrick transgression. Ravinement within this local embayment, rapid inundation by marine waters, and concentration of carbonate-bearing waters within transgressive scours may have contributed to the formation of coal balls and pyritic concretions in the upper part of the coal bed.

  15. Depositional systems in the lower Cretaceous Morro Do Chaves and Coqueiro Seco formations, and their relationship to petroleum accumulations, middle rift sequence, Sergipe-Alagoas Basin, Brazil

    SciTech Connect

    de Figueiredo, A.M.F.

    1981-01-01

    In the Sergipe-Alagoas Basin, northeast coast of Brazil, the Lower Cretaceous lacustrine, middle rift sequence is composed of the Morro do Chaves and Coqueiro Seco Formations. Subsurface analysis permitted recognition and mapping of four principal types of depositional environments: Morro do Chaves carbonate platform, and Coqueiro Seco fluvial-deltaic, fan delta, and slope systems. Morro do Chaves lacustrine carbonate sediments were deposited in positive areas flanking the principal point sources (rivers), and are composed of high energy limestones. Contemporaneous deep-water euxinic and bituminous lacustrine shales were deposited under starved basin conditions. Sublacustrine canyon excavation attested to the presence of a destructional slope episode. Coqueiro Seco fluvial-deltaic and fan delta facies display high sand/shale ratios and blocky to massive E-log patterns; slope facies display serrate to digitate E-log patterns and is less sandy. Delta plain channel-fill facies and coarse-grained meanderbelt fluvial facies are dominant in fluvial-deltaic systems of the Alagoas Sub-basin; and proximal to medial conglomerates and coarse conglomeratic sandstones are dominant facies in fan delta systems of the Rio Sao Francisco Sub-basin. Slope facies are composed of sublacustrine fans formed by fine- to medium-grained sandstones enveloped by subbituminous shales, and lacustrine limestones. Coqueiro Seco coarse clastic systems prograded across the basin and buried Morro do Chaves carbonate platforms in response to cyclic tectonic pulses related to rift development. Evaluation of petroleum occurrences in relationship to defined depositional systems permitted recognition of several types of plays characterized by unique structural and stratigraphic relationships exhibited by reservoirs, source beds and structure. The Coqueiro Seco slope play, formed by updip pinchout of turbidite fans, is judged the most promising in the sequence.

  16. Sulfur, carbon, and oxygen isotope variations in submarine hydrothermal deposits of Guaymas Basin, Gulf of California, USA

    USGS Publications Warehouse

    Peter, J.M.; Shanks, Wayne C.

    1992-01-01

    Sulfur, carbon, and oxygen isotope values were measured in sulfide, sulfate, and carbonate from hydrothermal chimney, spire, and mound samples in the southern trough of Guaymas Basin, Gulf of California, USA. ??34S values of sulfides range from -3.7 to 4.5%. and indicate that sulfur originated from several sources: 1. (1) dissolution of 0??? sulfide contained within basaltic rocks, 2. (2) thermal reduction of seawater sulfate during sediment alteration reactions in feeder zones to give sulfide with positive ??34S, and 3. (3) entrainment or leaching of isotopically light (negative-??34S) bacteriogenic sulfide from sediments underlying the deposits. ??34S of barite and anhydrite indicate sulfur derivation mainly from unfractionated seawater sulfate, although some samples show evidence of sulfate reduction and sulfide oxidation reactions during mixing within chimneys. Oxygen isotope temperatures calculated for chimney calcites are in reasonable agreement with measured vent fluid temperatures and fluid inclusion trapping temperatures. Hydrothermal fluids that formed calcite-rich chimneys in the southern trough of Guaymas Basin were enriched in 18O with respect to seawater by about 2.4??? due to isotopic exchange with sedimentary and/or basaltic rocks. Carbon isotope values of calcite range from -9.6 to -14.0??? ??34CpDB, indicating that carbon was derived in approximately equal quantities from the dissolution of marine carbonate minerals and the oxidation of organic matter during migration of hydrothermal fluid through the underlying sediment column. Statistically significant positive, linear correlations of ??34S, ??34C, and ??18O of sulfides and calcites with geographic location within the southern trough of Guaymas Basin are best explained by variations in water/rock ( w r) ratios or sediment reactivity within subsurface alteration zones. Low w r ratios and the leaching of detrital carbonates and bacteriogenic sulfides at the southern vent sites result in relatively

  17. Pseudomorphs of Neotethyan Evaporites in Anatolia's HP/LT belts - Aptian basin-wide pelagic gypsum deposits

    NASA Astrophysics Data System (ADS)

    Scheffler, Franziska; Oberhänsli, Roland; Pourteau, Amaury; Immenhauser, Adrian; Candan, Osman

    2015-04-01

    Rosetta Marble was defined in SW Anatolia as 3D-radiating textures of dm-to-m-long calcite rods in the HP/LT metamorphosed Mid-Cretaceous pelagic carbonate sequence of the Ören Unit. Rosetta Marble in the type locality are interbedded with meta-chert beds, and may constitute entire carbonate beds. Rare aragonite relicts and Sr-rich, fibrous calcite pseudomorphs after aragonite witness the HP metamorphic imprint of this sequence during the closure of a Neotethyan oceanic domain during latest Cretaceous-Palaeocene times. We investigated the Rosetta Marble of the Ören Unit, as well as other known and newly found localities in the Tavşanlı and Afyon zones, and the Alanya Massif and Malatya area, to decipher the metamorphic, diagenetic and sedimentologic significance of these uncommon textures. Based on field, petrographic and geochemical investigations, we document a wide variety of Rosetta-type textures. A striking resemblance with well-known gypsum morphologies (e.g. shallow-tail, palm-tree textures) leads us to argue that Rosetta Marble was initially composed of giant gypsum crystals (selenite). The absence of anhydrite relicts of pseudomorphs indicate that gypsum transformed into calcite soon after the deposition by the mean of a sulphate reduction reaction. The gypsum-to-calcite transformation requires that organic matter intervened as a reactant phase. Mid Cretaceous oceanic domains in the Tethyan realm are characterised by overall anoxic conditions that allowed the preservation of organic material. Rosetta Marble exposures are widely distributed over 600 km along the Neotethyan suture zone. During deepening of the Neotethyan ocean in Mid Cretaceous times, basin-wide and cyclic sedimentation of gypsum and radiolarite occurred. The origin of high-salinity waters needed for gypsum precipitation was located at shelf levels. Density and gravity effects forced the brines to cascade downwards into the deep ocean. Favorable climatic conditions trigger the formation

  18. Na-Cl-Br systematics of fluid inclusions from Mississippi Valley-type deposits, Appalachian Basin: Constraints on solute origin and migration paths

    SciTech Connect

    Kesler, S.E.; Martini, A.M.; Appold, M.S.; Walter, L.M.; Huston, T.J.; Furman, F.C.

    1996-01-01

    This study evaluated Na-Cl-Br systematics of fluid inclusion-hosted brines in Mississippi Valley-type (MVT) deposits from the Appalachian Basin. Unlike other geochemical tracers such as lead and strontium isotopes which constrain metal sources, Na-Cl-Br systematics identify sources of brine salinity. Saline formation waters can vary systematically within and between basins with regard to their Na-Cl-Br compositions depending on the importance of halite dissolution relative to retention of subaerially evaporated seawater for the halogen budget. Oil field brine compositions from the Illinois and Appalachian basins are quite distinct in their Na-Cl-Br systematics. Compositions of saline fluid inclusions in MVT deposits generally are consistent with these regional differences. These results shed new light on the extent of regional flow systems and on the geochemical evolution of saline fluids responsible for mineralization. Nearly all fluid inclusions analyzed from the Appalachian MVT deposits have Na/Br and Cl/Br ratios less than modern seawater, consistent with ratios observed in marine brines involved in halite precipitation. The Na-Cl-Br systematics of the brines responsible for Appalachian MVT deposits may be inherited from original marine brines refluxed into the porous carbonate shelf sediments that host these deposits. The Cl/Br and Na/Br ratios of most fluid inclusion-hosted brines from Appalachian MVT sphalerites and fluorites fall into two compositional groups, one from the Lower Cambrian paleoaquifer and another from the Lower Ordovician paleoaquifer. Leachates from most MVT barite deposits form a third compositional group having lower Na/Br and Cl/Br ratios than the other two. Appalachian MVT leachate compositions differ significantly from those in MVT deposits in the Cincinnati arch-midcontinent region suggesting that these two MVT provinces formed from brines of different origin or flow path. 59 refs., 8 figs., 2 tabs.

  19. Growth pattern research on the modern deposition of Ganjiang delta in Poyang lake basin by spatio-temporal remote sensing images

    NASA Astrophysics Data System (ADS)

    Zhou, Hongying; Yuan, Xuanjun; Zhang, Youyan; Dong, Wentong; Liu, Song

    2016-11-01

    It is of great importance for petroleum exploration to study the sedimentary features and the growth pattern of shoal water deltas in lake basins. Taking spatio-temporal remote sensing images as the principal data source, combined with field sedimentation survey, a quantitative research on the modern deposition of Ganjiang delta in the Poyang Lake Basin is described in this paper. Using 76 multi-temporal and multi-type remote sensing images acquired from 1973 to 2015, combined with field sedimentation survey, remote sensing interpretation analysis was conducted on the sedimentary facies of the Ganjiang delta. It is found that that the current Poyang Lake mainly consists of three types of sand body deposits including deltaic deposit, overflow channel deposit, and aeolian deposit, and the distribution of sand bodies was affected by the above three types of depositions jointly. The mid-branch channels of the Ganjiang delta increased on an exponential growth rhythm. The main growth pattern of the Ganjiang delta is dendritic and reticular, and the distributary channel mostly arborizes at lake inlet and was reworked to be reticulatus at late stage.

  20. Whole watershed quantification of net carbon fluxes by erosion and deposition within the Christina River Basin Critical Zone Observatory

    NASA Astrophysics Data System (ADS)

    Aufdenkampe, A. K.; Karwan, D. L.; Aalto, R. E.; Marquard, J.; Yoo, K.; Wenell, B.; Chen, C.

    2012-12-01

    We have proposed that the rate at which fresh, carbon-free minerals are delivered to and mix with fresh organic matter determines the rate of carbon preservation at a watershed scale (Aufdenkampe et al. 2011). Although many studies have examined the role of erosion in carbon balances, none consider that fresh carbon and fresh minerals interact. We believe that this mechanism may be a dominant sequestration process in watersheds with strong anthropogenic impacts. Our hypothesis - that the rate of mixing fresh carbon with fresh, carbon-free minerals is a primary control on watershed-scale carbon sequestration - is central to our Christina River Basin Critical Zone Observatory project (CRB-CZO, http://www.udel.edu/czo/). The Christina River Basin spans 1440 km2 from piedmont to Atlantic coastal plain physiographic provinces in the states of Pennsylvania and Delaware, and experienced intensive deforestation and land use beginning in the colonial period of the USA. Here we present a synthesis of multi-disciplinary data from the CRB-CZO on materials as they are transported from sapprolite to topsoils to colluvium to suspended solids to floodplains, wetlands and eventually to the Delaware Bay estuary. At the heart of our analysis is a spatially-integrated, flux-weighted comparison of the organic carbon to mineral surface area ratio (OC/SA) of erosion source materials versus transported and deposited materials. Because source end-members - such as forest topsoils, farmed topsoils, gullied subsoils and stream banks - represent a wide distribution of initial, pre-erosion OC/SA, we quantify source contributions using geochemical sediment fingerprinting approaches (Walling 2005). Analytes used for sediment fingerprinting include: total mineral elemental composition (including rare earth elements), fallout radioisotope activity for common erosion tracers (beryllium-7, beryllium-10, lead-210, cesium-137), particle size distribution and mineral specific surface area, in addition

  1. Whole Watershed Quantification of Net Carbon Fluxes by Erosion and Deposition within the Christina River Basin Critical Zone Observatory

    NASA Astrophysics Data System (ADS)

    Aufdenkampe, A. K.; Karwan, D. L.; Aalto, R. E.; Marquard, J.; Yoo, K.; Wenell, B.; Chen, C.

    2013-12-01

    We have proposed that the rate at which fresh, carbon-free minerals are delivered to and mix with fresh organic matter determines the rate of carbon preservation at a watershed scale (Aufdenkampe et al. 2011). Although many studies have examined the role of erosion in carbon balances, none consider that fresh carbon and fresh minerals interact. We believe that this mechanism may be a dominant sequestration process in watersheds with strong anthropogenic impacts. Our hypothesis - that the rate of mixing fresh carbon with fresh, carbon-free minerals is a primary control on watershed-scale carbon sequestration - is central to our Christina River Basin Critical Zone Observatory project (CRB-CZO, http://www.udel.edu/czo/). The Christina River Basin spans 1440 km2 from piedmont to Atlantic coastal plain physiographic provinces in the states of Pennsylvania and Delaware, and experienced intensive deforestation and land use beginning in the colonial period of the USA. Here we present a synthesis of multi-disciplinary data from the CRB-CZO on materials as they are transported from sapprolite to topsoils to colluvium to suspended solids to floodplains, wetlands and eventually to the Delaware Bay estuary. At the heart of our analysis is a spatially-integrated, flux-weighted comparison of the organic carbon to mineral surface area ratio (OC/SA) of erosion source materials versus transported and deposited materials. Because source end-members - such as forest topsoils, farmed topsoils, gullied subsoils and stream banks - represent a wide distribution of initial, pre-erosion OC/SA, we quantify source contributions using geochemical sediment fingerprinting approaches (Walling 2005). Analytes used for sediment fingerprinting include: total mineral elemental composition (including rare earth elements), fallout radioisotope activity for common erosion tracers (beryllium-7, beryllium-10, lead-210, cesium-137), particle size distribution and mineral specific surface area, in addition

  2. Sequential extraction techniques applied to a porphyry copper deposit in the basin and range province

    USGS Publications Warehouse

    Filipek, L.H.; Theobald, P.K.

    1981-01-01

    Samples of minus-80-mesh (<180 ??m) stream sediment, rock containing exposed fracture coatings, and jarosite and chrysocolla were collected from an area surrounding the North Silver Bell porphyry Cu deposit near Tucson, Arizona. The samples were subjected to a series of extractions in a scheme originally designed for use on samples from humid or sub-humid environments, in which the following fractions can effectively be separated: (1) carbonates and exchangeable metals; (2) Mn oxides; (3) organic compounds and sulfides; (4) hydrous Fe oxides; and (5) residual crystalline minerals. Jarosite and chrysocolla, two major minerals of the North Silver Bell area, were found to dissolve over two or more steps of the extraction scheme. The results represent only a limited number of samples from one copper deposit. Nevertheless, they do suggest that in a semiarid to arid environment, where mechanical dispersion of such minerals predominates, uncritical assignment of unique phases, such as Mn oxides or organics to a given extraction would lead to false interpretations of weathering processes. However, the relative proportions of elements dissolved in each step of the jarosite and chrysocolla extractions could be used as a "fingerprint" for recognition of the presence of these two minerals in the stream-sediment and rock samples. The relative abundance of hydrous Fe oxide and jarosite and the alteration zoning could be mapped using data from jarosite and chrysocolla extractions. Manganese oxides were also found to have a greater influence on Zn than on Cu or Pb during supergene alteration. The rapid change in relative importance of the first (1M-acetic acid) extraction for Cu, Zn, and Pb near the mineralized zone suggested the occurrence of minor hydromorphic processes within the stream sediments. Thus, the acetic acid extraction proved the most effective for pinpointing mineralization in sediments. In contrast, the residual fraction had the longest dispersion train, suggesting

  3. Hydrothermal deposits in the Southern Trough of Guaymas Basin, Gulf of California: Observations and Preliminary Results from the 2003 MBARI Dive Program

    NASA Astrophysics Data System (ADS)

    Stakes, D. S.; Tivey, M. K.; Koski, R. A.; Ortego-Osorio, A.; Preston, C. M.; McCulloch, M. T.; Nakamura, K.; Seewald, J.; Wheat, C. G.

    2003-12-01

    During Leg 2 of the 2003 MBARI expedition to the Gulf of California, the ROV Tiburon completed eight dives to active vent fields in the Southern Trough of Guaymas Basin. Six venting areas were investigated in detail. Tiburon operations included (1) sampling mineral deposits that range from mini-chimneys a few centimeters high to 10-meter-tall sulfide-carbonate structures with wide flanges; (2) collection of 90C to 303C methane, carbon dioxide, and hydrogen-rich vent fluids in gas-tight samplers and plume-laden particulates in Niskin samplers; 3) collection of warm (up to 83C) hydrocarbon-rich sediment push cores; 4) long-term monitoring of three vent sites using thermocouple arrays (see adjacent Tivey et al poster) and osmotically-driven fluid samplers. Seventy days later, the ROV returned to recover the thermocouple arrays and ingrown chimneys. At the lowest temperature sites, fluid (up to 90C) discharged from orifices in sediment surrounded by white to yellow microbial mats. Combined Eh-ISUS (InSitu Ultraviolet Spectrophotometer) sensors mounted on Tiburon identified local increases in bisulfide and decreases in the oxidation/reduction potential (a proxy for methane and hydrogen sulfide) associated with these sites. Massive barite chimneys recovered from the margins of moderate-temperature vent sites are permeated with oil. Chimneys from higher temperature sites, in contrast, lack the liquid hydrocarbon component, and are largely composed of calcium carbonate with lesser anhydrite, amorphous silica, barite, pyrrhotite, Mg-silicate, galena, sphalerite, and chalcopyrite. Mineral precipitation at the southernmost site (Toadstool) is characterized by the formation of carbonate-rich flanges directly above a substrate of altered diatomaceous sediment. The upper sediment crust lies above a stockwork of calcite veins. High-temperature structures at Rebecca's Roost and Broken Mushroom have pagoda-like carbonate-rich flanges trapping pools of hydrothermal fluids that

  4. Alluvial deposits from the strike-slip fault Lo River Basin (Oligocene/Miocene), Red River Fault Zone, north-western Vietnam

    NASA Astrophysics Data System (ADS)

    Wysocka, Anna; Swierczewska, Anna

    2003-08-01

    The Lo River Basin (LRB) is one of several narrow sedimentary basins associated with the main faults of the Red River Fault Zone separating the South China and Indochina microplates. The basin is located on the NE boundary of the high-grade metamorphic Con Voi Massif and the sedimentary and metasedimentary Viet Bac fold zone in north-eastern Vietnam. The LRB is filled with over 6000 m of Oligocene/Miocene alluvial deposits. The source area was probably located on the NE margin of the basin and was composed mostly of low-grade metamorphic rocks with a minor component of sedimentary rocks. Three alluvial systems are recognised. The oldest system was a proximal braided river system, with the minor occurrence of alluvial fans. The younger systems record changes in clast composition and lithofacies, which suggests a transition from a distal braided river to a distal braidplain system. The LRB fill shows a range of features characteristic of strike-slip fault basins. The origin of the LRB is correlated with the left-lateral transtensional regime. The present shape of the basin is a result of post-sedimentation tectonic activity.

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

    NASA Astrophysics Data System (ADS)

    Kowler, A. L.

    2010-12-01

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

  6. Sedimentological characterization of flood-tidal delta deposits in the Sego Sandstone, subsidence analysis in the Piceance Creek Basin, and uranium-lead geochronology (NW Colorado, USA)

    NASA Astrophysics Data System (ADS)

    York, Carly C.

    The Sego Sandstone located in western Colorado is a member of the Upper Cretaceous Mesaverde Group and is considered an analogue of the Canadian heavy oil sands. Deposition of the Sego Sandstone occurred during the Upper Campanian (~78 Ma) at the end of the Sevier Orogeny and the beginning of the Laramide Orogeny on the western edge of the Cretaceous Interior Seaway. Although regional studies have detailed time equivalent deposits in the Book Cliffs, UT, the tidally influenced and marginal marine lithofacies observed north of Rangely, CO are distinctly different from the dominately fluvial and tidally-influenced delta facies of Book Cliff outcrops to the southwest. This study characterized flood-tidal delta deposits within the Sego Sandstone, the subsidence history of the Upper Cretaceous sedimentary rocks within the present day Piceance Creek Basin in NW Colorado, and the detrital zircon signal and oldest depositional age of the Sego Sandstone. The goals of this study are to (i) identify relative controls on reservoir characteristics of marginal marine deposits, specifically in flood-tidal delta deposits; (ii) identify the possible mechanisms responsible for subsidence within the present day Piceance Creek Basin during the Late Cretaceous; and (iii) better constrain the provenance and maximum depositional age of the Sego Sandstone. In this study I compared grain size diameter, grain and cement composition, and the ratio of pore space/cement from thin sections collected in tidal, shoreface, and flood-tidal delta facies recognized along detailed measured stratigraphic sections. This analysis provides a detailed comparison between different depositional environments and resultant data showed that grain size diameter is different between tidal, shoreface, and flood-tidal delta facies. Identifying the subsidence mechanisms affecting the Piceance Creek Basin and sediment source of the Late Cretaceous sediments, on the other hand, is important for evaluation of controls

  7. Vanadium chlorite from a sandstone-hosted vanadium-uranium deposit, Henry basin, Utah.

    USGS Publications Warehouse

    Whitney, G.; Northrop, H.R.

    1986-01-01

    This ore deposit formed by reduction and precipitation of U and V in the presence of organic matter at the interface between a stagnant brine and overlying circulating meteoric water. Some samples of the vanadium chlorite (heated before analysis) contain = or >10% V2O5; in fresh samples most of the V is in the V3+ state. XRD data suggest that Fe and V are concentrated preferentially in the interlayer hydroxide sheets of the chlorite. A d060 value of 1.52 A indicates that the chlorite probably has a dioctahedral structure distended by the presence of octahedral Fe and V; it is a IIb polytype. The V ore zone is flanked by peripheral zones with perfectly ordered chlorite/smectite containing much less V than the pure chlorite. Chemical analysis of a sample heated to 900oC before analysis gave SiO2 44.89, Al2O3 25.14, TiO2 0.35, Fe2O3 8.29, MgO 8.47, CaO 0.84, Na2O 0.27, K2O 2.18, Li2O 0.16, UO3 0.92, V2O5 9.14, = 100.65, together with Cr 10, Mn 200, Co 150, Ni 5.8, Cu 10, Zn 140 ppm; XRD, DTG, TG and IR curves are presented. -R.A.H.

  8. Holocene valley-floor deposition and incision in a small drainage basin in western Colorado, USA

    NASA Astrophysics Data System (ADS)

    Jones, Lawrence S.; Rosenburg, Margaret; Figueroa, Maria del Mar; McKee, Kathleen; Haravitch, Ben; Hunter, Jenna

    2010-09-01

    The valley floor of a 33.9 km 2 watershed in western Colorado experienced gradual sedimentation from before ˜ 6765 to ˜ 500 cal yr BP followed by deep incision, renewed aggradation, and secondary incision. In contrast, at least four terraces and widespread cut-and-fill architecture in the valley floor downstream indicate multiple episodes of incision and deposition occurred during the same time interval. The upper valley fill history is atypical compared to other drainages in the Colorado Plateau. One possible reason for these differences is that a bedrock canyon between the upper and lower valley prevented headward erosion from reaching the upper valley fill. Another possibility is that widespread, sand-rich, clay-poor lithologies in the upper drainage limited surface runoff and generally favored alluviation, whereas more clay-rich lithologies in the lower drainage resulted in increased surface runoff and more frequent incision. Twenty-two dates from valley fill charcoal indicate an approximate forest fire recurrence interval of several hundred years, similar to that from other studies in juniper-piñon woodlands. Results show that closely spaced vertical sampling of alluvium in headwater valleys where linkages between hillslope processes and fluvial activity are relatively direct can provide insight about the role of fires in alluvial chronologies of semi-arid watersheds.

  9. Biochronostratigraphy and paleoenvironment analysis of Neogene deposits from the Pelotas Basin (well 2-TG-96-RS), Southernmost Brazil.

    PubMed

    Silva, Wagner G; Zerfass, Geise S A; Souza, Paulo A; Helenes, Javier

    2015-09-01

    This paper presents the integration of micropaleontological (palynology and foraminifera) and isotopic (87Sr/86Sr) analysis of a selected interval from the well 2-TG-96-RS, drilled on the onshore portion of the Pelotas Basin, Rio Grande do Sul, Brazil. A total of eight samples of the section between 140.20 and 73.50 m in depth was selected for palynological analysis, revealing diversified and abundant palynomorph associations. Species of spores, pollen grains and dinoflagellate cysts are the most common palynomorphs found. Planktic and benthic calcareous foraminifera were recovered from the lowest two levels of the section (140.20 and 134.30 m). Based on the stratigraphic range of the species of dinoflagellate cysts and sporomorphs, a span age from Late Miocene to Early Pliocene is assigned. The relative age obtained from the 87Sr/86Sr ratio in shells of calcareous foraminifers indicates a Late Miocene (Messinian) correspondence, corroborating the biostratigraphic positioning performed with palynomorphs. Paleoenvironmental interpretations based on the quantitative distribution of organic components (palynomorphs, phytoclasts and amorphous organic matter) throughout the section and on foraminiferal associations indicate a shallow marine depositional environment for the section. Two palynologicals intervals were recognized based on palynofacies analysis, related to middle to outer shelf (140.20 to 128.90 m) and inner shelf (115.75 to 73.50 m) conditions.

  10. The balance between deposition and subsidence (tectonics) in a rift basin playa and its effect on the climatic record of an area: Evidence from Bristol Dry Lake, California

    SciTech Connect

    Rosen, M.R. )

    1991-03-01

    Two continuous core intervals drilled in Bristol Dry Lake, a large (150 km{sup 2}) playa in the central Mojave Desert of California, penetrated over 500 m of sediment and did not reach basement. The repetitious nature of the alternating shallow brine pond halite and siliciclastic and the consistency of the carbonate isotopic data from the surface and core indicate a relatively stable brine composition for most of the history of Bristol Dry Lake. All sedimentary structures and primary halite fabrics in the core indicate shallow-water, brine-pond halite alternated with halite-saturated siliciclastic muds in the basin center. A delicate balance of subsidence and mechanical and chemical deposition of evaporite and siliciclastic minerals was necessary to maintain the largely ephemeral lake environment of deposition through over 550 m of basin fill. The alternating brine pond/saline lake setting in Bristol Dry Lake is not directly related to climatic influences, and the sediments do not record major climatic events demonstrated in other closed-basin lakes. The reason for this insensitivity to climatic events is explained by the interior location of the basin, the low relief of the mountains surrounding the catchment, the large surface area of the catchment, and the low average sedimentation rates. All of the above criteria are at least partially controlled by the tectonics of the area, which, in turn, affect the sedimentation rate and supply water to the basin. Therefore, it is important to consider the influence of the above factors in determining global versus local, or regional, climate curves for a particular basin.

  11. The Cuenca de Oro, a Pull-Apart Basin Hosting Precious Metal Deposits Along the Re- Activated Seri-Tahue Terrane Boundary

    NASA Astrophysics Data System (ADS)

    Feinstein, M. N.; Goodell, P. C.

    2007-05-01

    At the intersection of Chihuahua, Sonora, and Sinaloa a boundary between the Seri and Tahue terranes has been hypothesized, and further refined as the Sinforosa Lineament. Near the western termination of the Sinforosa Lineament lies a topographic basin. Part of this study will be to better define this pull-apart basin, informally named the Cuenca de Oro due to its numerous precious metal deposits. The intention of this study is to test that the Seri-Tahue terrane boundary was re-energized during the beginning of extension related to the opening of the Sea of Cortez (~30ma). It is probable that the precious metal occurrences are related to the initiation of extension(alunite at El Sauzal has been dated at ~30ma). Five field excursions totaling sixty days of field work have been completed and a first draft of a regional geologic map has been made. Large shear zones support the hypothesis of a pull-apart basin. A study of the alteration and lineament intersections determine the location of many known precious metal deposits. By creating multiple cross-sections the basin can be modeled in three dimensions and a tectonic history can be interpreted. This study will present a structural analysis of the Cuenca de Oro and develop a tectonic history related temporally with the epithermal mineralization events.

  12. Attributes for MRB_E2RF1 Catchments by Major River Basins in the Conterminous United States: Normalized Atmospheric Deposition for 2002, Nitrate (NO3)

    USGS Publications Warehouse

    Wieczorek, Michael; LaMotte, Andrew E.

    2010-01-01

    This tabular data set represents the average normalized (wet) deposition, in kilograms per square kilometer multiplied by 100, of Nitrate (NO3) for the year 2002 compiled for every MRB_E2RF1 catchment of the Major River Basins (MRBs, Crawford and others, 2006). Estimates of NO3 deposition are based on National Atmospheric Deposition Program (NADP) measurements (B. Larsen, U.S. Geological Survey, written. commun., 2007). De-trending methods applied to the year 2002 are described in Alexander and others, 2001. NADP site selection met the following criteria: stations must have records from 1995 to 2002 and have a minimum of 30 observations. The MRB_E2RF1 catchments are based on a modified version of the U.S. Environmental Protection Agency's (USEPA) ERF1_2 and include enhancements to support national and regional-scale surface-water quality modeling (Nolan and others, 2002; Brakebill and others, 2011). Data were compiled for every MRB_E2RF1 catchment for the conterminous United States covering New England and Mid-Atlantic (MRB1), South Atlantic-Gulf and Tennessee (MRB2), the Great Lakes, Ohio, Upper Mississippi, and Souris-Red-Rainy (MRB3), the Missouri (MRB4), the Lower Mississippi, Arkansas-White-Red, and Texas-Gulf (MRB5), the Rio Grande, Colorado, and the Great basin (MRB6), the Pacific Northwest (MRB7) river basins, and California (MRB8).

  13. Attributes for MRB_E2RF1 Catchments by Major River Basins in the Conterminous United States: Normalized Atmospheric Deposition for 2002, Ammonium (NH4)

    USGS Publications Warehouse

    Wieczorek, Michael; LaMotte, Andrew E.

    2010-01-01

    This tabular data set represents the average normalized (wet) deposition, in kilograms per square kilometer multiplied by 100, of ammonium (NH4) for the year 2002 compiled for every MRB_E2RF1 catchment of the Major River Basins (MRBs, Crawford and others, 2006). Estimates of NH4 deposition are based on National Atmospheric Deposition Program (NADP) measurements (B. Larsen, U.S. Geological Survey, written. commun., 2007). De-trending methods applied to the year 2002 are described in Alexander and others, 2001. NADP site selection met the following criteria: stations must have records from 1995 to 2002 and have a minimum of 30 observations. The MRB_E2RF1 catchments are based on a modified version of the U.S. Environmental Protection Agency's (USEPA) ERF1_2 and include enhancements to support national and regional-scale surface-water quality modeling (Nolan and others, 2002; Brakebill and others, 2011). Data were compiled for every MRB_E2RF1 catchment for the conterminous United States covering New England and Mid-Atlantic (MRB1), South Atlantic-Gulf and Tennessee (MRB2), the Great Lakes, Ohio, Upper Mississippi, and Souris-Red-Rainy (MRB3), the Missouri (MRB4), the Lower Mississippi, Arkansas-White-Red, and Texas-Gulf (MRB5), the Rio Grande, Colorado, and the Great basin (MRB6), the Pacific Northwest (MRB7) river basins, and California (MRB8).

  14. Application of mineral-solution equilibria to geochemical exploration for sandstone-hosted uranium deposits in two basins in west central Utah.

    USGS Publications Warehouse

    Miller, W.R.; Wanty, R.B.; McHugh, J.B.

    1984-01-01

    This study applies mineral-solution equilibrium methods to the interpretation of ground-water chemistry in evaluating the uranium potential of the Beaver and Milford basins in west central Utah. Waters were collected mainly from wells and springs at 100 sites in limited areas in the basins, and in part from mixed sources. The waters were analysed for T, pH, alkalinity, specific conductance, SO4, Cl, F, NO3, Ca, Mg, Na, K, SiO2, Zn, Cu, Mo, As, U, V, Se, Li, Fe, Mn, and Al on different fractions. A computer model (WATEQ3) was used to calculate the redox potential and the state of saturation of the waters with respect to uraninite, coffinite, realgar and arsenopyrite. Mineral saturation studies have reliably predicted the location of known (none given here) U deposits and are more diagnostic of these deposits than are concentrations of indicator elements (U, Mo, As, Se). Several areas in the basins have ground-water environments of reducing redox potential, favourable for precipitation of reduced U minerals, and some of these areas are saturated or near-saturated with respect to uraninite and coffinite. The approach shows only that the environment is favourable locally for precipitation of reduced U minerals, but thereby locates exploration targets for (modern?) sandstone-hosted U deposits.-G.J.N.

  15. Attributes for MRB_E2RF1 Catchments by Major River Basins in the Conterminous United States: Normalized Atmospheric Deposition for 2002, Total Inorganic Nitrogen

    USGS Publications Warehouse

    Wieczorek, Michael; LaMotte, Andrew E.

    2010-01-01

    This tabular data set represents the average normalized atmospheric (wet) deposition, in kilograms per square kilometer multiplied by 100, of Total Inorganic Nitrogen for the year 2002 compiled for every MRB_E2RF1 catchment of selected Major River Basins (MRBs, Crawford and others, 2006). Estimates of Total Inorganic Nitrogen deposition are based on National Atmospheric Deposition Program (NADP) measurements (B. Larsen, U.S. Geological Survey, written. commun., 2007). De-trending methods applied to the year 2002 are described in Alexander and others, 2001. NADP site selection met the following criteria: stations must have records from 1995 to 2002 and have a minimum of 30 observations. The MRB_E2RF1 catchments are based on a modified version of the U.S. Environmental Protection Agency's (USEPA) ERF1_2 and include enhancements to support national and regional-scale surface-water quality modeling (Nolan and others, 2002; Brakebill and others, 2011). Data were compiled for every MRB_E2RF1 catchment for the conterminous United States covering New England and Mid-Atlantic (MRB1), South Atlantic-Gulf and Tennessee (MRB2), the Great Lakes, Ohio, Upper Mississippi, and Souris-Red-Rainy (MRB3), the Missouri (MRB4), the Lower Mississippi, Arkansas-White-Red, and Texas-Gulf (MRB5), the Rio Grande, Colorado, and the Great basin (MRB6), the Pacific Northwest (MRB7) river basins, and California (MRB8).

  16. Sulfur redox reactions: Hydrocarbons, native sulfur, Mississippi Valley-type deposits, and sulfuric acid karst in the Delaware Basin, New Mexico and Texas

    SciTech Connect

    Hill, C.A.

    1995-02-01

    Hydrocarbons, native sulfur, Mississippi Valley-type (MVT) deposits, and sulfuric acid karst in the Delaware Basin, southeastern New Mexico, and west Texas, USA, are all genetically related through a series of sulfur redox reactions. The relationship began with hydrocarbons in the basin that reacted with sulfate ions from evaporite rock to produce isotopically light ({delta}{sup 34}S = -22 to -12) H{sub 2}S and bioepigenetic limestone (castiles). This light H{sub 2}S was then oxidized at the redox interface to produce economic native sulfur deposits ({delta}{sup 34}S = -15 to +9) in the castiles, paleokarst, and along graben-boundary faults. This isotopically light H{sub 2}S also migrated from the basin into its margins to accumulate in structural (anticlinal) and stratigraphic (Yates siltstone) traps, where it formed MVT deposits within the zone of reduction ({delta}{sup 34}S = -15 to +7). Later in time, in the zone of oxidation, this H{sub 2}S reacted with oxygenated water to produce sulfuric acid, which dissolved the caves (e.g., Carlsbad Cavern and Lechuguilla Cave, Guadalupe Mountains). Massive gypsum blocks on the floors of the caves ({delta}{sup 34}S = -25 to +4) were formed as a result of this reaction. The H{sub 2}S also produced isotopically light cave sulfur ({delta}{sup 34}S = -24 to -15), which is now slowly oxidizing to gypsum in the presence of vadose drip water. 16 refs., 10 figs.

  17. Combined impacts of current and future dust deposition and regional warming on Colorado River Basin snow dynamics and hydrology

    USGS Publications Warehouse

    Deems, Jeffrey S.; Painter, Thomas H.; Barsugli, Joseph J.; Belnap, Jayne; Udall, Bradley

    2013-01-01

    The Colorado River provides water to 40 million people in seven western states and two countries and to 5.5 million irrigated acres. The river has long been overallocated. Climate models project runoff losses of 5–20% from the basin by mid-21st century due to human-induced climate change. Recent work has shown that decreased snow albedo from anthropogenic dust loading to the CO mountains shortens the duration of snow cover by several weeks relative to conditions prior to western expansion of the US in the mid-1800s, and advances peak runoff at Lees Ferry, Arizona, by an average of 3 weeks. Increases in evapotranspiration from earlier exposure of soils and germination of plants have been estimated to decrease annual runoff by more than 1.0 billion cubic meters, or ~5% of the annual average. This prior work was based on observed dust loadings during 2005–2008; however, 2009 and 2010 saw unprecedented levels of dust loading on snowpacks in the Upper Colorado River Basin (UCRB), being on the order of 5 times the 2005–2008 loading. Building on our prior work, we developed a new snow albedo decay parameterization based on observations in 2009/10 to mimic the radiative forcing of extreme dust deposition. We convolve low, moderate, and extreme dust/snow albedos with both historic climate forcing and two future climate scenarios via a delta method perturbation of historic records. Compared to moderate dust, extreme dust absorbs 2× to 4× the solar radiation, and shifts peak snowmelt an additional 3 weeks earlier to a total of 6 weeks earlier than pre-disturbance. The extreme dust scenario reduces annual flow volume an additional 1% (6% compared to pre-disturbance), a smaller difference than from low to moderate dust scenarios due to melt season shifting into a season of lower evaporative demand. The sensitivity of flow timing to dust radiative forcing of snow albedo is maintained under future climate scenarios, but the sensitivity of flow volume reductions decreases

  18. Combined impacts of current and future dust deposition and regional warming on Colorado River Basin snow dynamics and hydrology

    NASA Astrophysics Data System (ADS)

    Deems, J. S.; Painter, T. H.; Barsugli, J. J.; Belnap, J.; Udall, B.

    2013-05-01

    The Colorado River provides water to 40 million people in seven states and two countries and to 5.5 million irrigated acres. The river has long been overallocated. Climate models project runoff losses of 5-20% from the basin by mid-21st century due to human-induced climate change. Recent work has shown that decreased snow albedo from anthropogenic dust loading to the CO mountains shortens the duration of snow cover by several weeks relative to conditions prior to white settlement of the western US, and advances peak runoff at Lees Ferry, Arizona by an average of 3 weeks. Increases in evapotranspiration from earlier exposure of soils and germination of plants have been estimated to decrease annual runoff by more than 1.0 billion cubic meters or ~ 5% of the annual average. This prior work was based on observed dust loadings during 2005-2008; however, 2009 and 2010 saw unprecedented levels of dust loading on snowpacks in the Upper Colorado River Basin (UCRB), being on the order of 5 times the 2005-2008 loading. Building on our prior work, we developed a new snow albedo decay parameterization based on observations in 2009/2010 to mimic the radiative forcing of extreme dust deposition. We convolve low, moderate, and extreme dust/snow albedos with both historic climate forcing and two future climate scenarios via a delta method perturbation of historic records. Compared to moderate dust, extreme dust absorbs 2 × to 4 × the solar radiation, and shifts peak snowmelt an additional 3 weeks earlier to a total of 6 weeks earlier than pre-disturbance. The extreme dust scenario reduces annual flow volume an additional 1% (6% compared to pre-disturbance), a smaller difference than from low to moderate due to melt season shifting into a season of lower evaporative demand. The sensitivity of flow timing to dust radiative forcing of snow albedo is maintained under future climate scenarios, but the sensitivity of flow volume reductions decreases with increased climate forcing

  19. Combined impacts of current and future dust deposition and regional warming on Colorado River Basin snow dynamics and hydrology

    NASA Astrophysics Data System (ADS)

    Deems, J. S.; Painter, T. H.; Barsugli, J. J.; Belnap, J.; Udall, B.

    2013-11-01

    The Colorado River provides water to 40 million people in seven western states and two countries and to 5.5 million irrigated acres. The river has long been overallocated. Climate models project runoff losses of 5-20% from the basin by mid-21st century due to human-induced climate change. Recent work has shown that decreased snow albedo from anthropogenic dust loading to the CO mountains shortens the duration of snow cover by several weeks relative to conditions prior to western expansion of the US in the mid-1800s, and advances peak runoff at Lees Ferry, Arizona, by an average of 3 weeks. Increases in evapotranspiration from earlier exposure of soils and germination of plants have been estimated to decrease annual runoff by more than 1.0 billion cubic meters, or ~5% of the annual average. This prior work was based on observed dust loadings during 2005-2008; however, 2009 and 2010 saw unprecedented levels of dust loading on snowpacks in the Upper Colorado River Basin (UCRB), being on the order of 5 times the 2005-2008 loading. Building on our prior work, we developed a new snow albedo decay parameterization based on observations in 2009/10 to mimic the radiative forcing of extreme dust deposition. We convolve low, moderate, and extreme dust/snow albedos with both historic climate forcing and two future climate scenarios via a delta method perturbation of historic records. Compared to moderate dust, extreme dust absorbs 2× to 4× the solar radiation, and shifts peak snowmelt an additional 3 weeks earlier to a total of 6 weeks earlier than pre-disturbance. The extreme dust scenario reduces annual flow volume an additional 1% (6% compared to pre-disturbance), a smaller difference than from low to moderate dust scenarios due to melt season shifting into a season of lower evaporative demand. The sensitivity of flow timing to dust radiative forcing of snow albedo is maintained under future climate scenarios, but the sensitivity of flow volume reductions decreases with

  20. Application of REE geochemical signatures for Mesozoic sediment provenance to the Gettysburg Basin, Pennsylvania

    NASA Astrophysics Data System (ADS)

    Blake, Johanna M.; Peters, Stephen C.; Johannesson, Karen H.

    2017-03-01

    Rift basins adjacent to accreted terranes provide accommodation space for sediments eroded from these terranes. Despite similar depositional environments and geologic age, rocks of the Triassic Gettysburg Basin have approximately half the arsenic concentrations of the adjacent Newark Basin. Quartz-feldspar-lithics (QFL) diagrams and rare earth element (REE) geochemical signatures can inform sediment provenance. Here we investigate REE geochemical signatures of the sedimentary rocks in the Triassic Gettysburg rift basin, with the goal of distinguishing the main sources of siliciclastic sediment among the Appalachian foreland in the rift footwall from Piedmont arc and Iapetan continental margin rocks exposed in the hanging wall and ultimately understanding the geochemical cycling of arsenic to the Gettysburg Basin. Shale-normalized REE spider diagrams and Mann-Whitney tests on trace element ratios suggest that the Gettysburg Basin samples show patterns that most closely resemble those of the Iapetus Continental Slope Rise Iapetus Rift Volcanic, and Accretionary Complex deposits. Mann-Whitney Rank Sum analysis suggest that the Iapetus Continental Slope Rise terrane is the main source of sediments to the basin, which confirms results from prior QFL analysis and shows the utility of REE fingerprinting in provenance analysis. The main sources of sediment have smaller minimum and maximum arsenic concentrations than other terranes and the Newark Basin sediments, additionally suggesting the source of arsenic to the Gettysburg Basin is based upon specific terranes.

  1. The Cretaceous-Paleogene boundary deposit in the Gulf of Mexico: Large-scale oceanic basin response to the Chicxulub impact

    NASA Astrophysics Data System (ADS)

    Sanford, Jason C.; Snedden, John W.; Gulick, Sean P. S.

    2016-03-01

    Hydrocarbon exploration in the last decade has yielded sufficient data to evaluate the Gulf of Mexico basin response to the Chicxulub asteroid impact. Given its passive marine setting and proximity to the impact structure on the Yucatán Peninsula, the gulf is the premier locale in which to study the near-field geologic effect of a bolide impact. We mapped a thick (decimeter- to hectometer-scale) deposit of carbonate debris at the Cretaceous-Paleogene boundary that is ubiquitous in the gulf and readily identifiable on borehole and seismic data. We interpret deposits seen in seismic and borehole data in the deepwater gulf to be predominately muddy debrites with minor turbidites based on cores in the southeastern gulf. Mapping of the deposit in the northern Gulf of Mexico reveals that the impact redistributed roughly 1.05 × 105 km3 of sediment therein and over 1.98 × 105 km3 gulfwide. Deposit distribution suggests that the majority of sediment derived from coastal and shallow-water environments throughout the gulf via seismic and megatsunamic processes initiated by the impact. The Texas shelf and northern margin of the Florida Platform were significant sources of sediment, while the central and southern Florida Platform underwent more localized platform collapse. The crustal structure of the ancestral gulf influenced postimpact deposition both directly and indirectly through its control on salt distribution in the Louann Salt Basin. Nevertheless, impact-generated deposition overwhelmed virtually all topography and depositional systems at the start of the Cenozoic, blanketing the gulf with carbonate debris within days.

  2. Depositional setting, petrology and chemistry of Permian coals from the Paraná Basin: 2. South Santa Catarina Coalfield, Brazil

    USGS Publications Warehouse

    Kalkreuth, W.; Holz, M.; Mexias, A.; Balbinot, M.; Levandowski, J.; Willett, J.; Finkelman, R.; Burger, H.

    2010-01-01

    In Brazil economically important coal deposits occur in the southern part of the Paran?? Basin, where coal seams occur in the Permian Rio Bonito Formation, with major coal development in the states of Rio Grande de Sul and Santa Catarina. The current paper presents results on sequence stratigraphic interpretation of the coal-bearing strata, and petrological and geochemical coal seam characterization from the South Santa Catarina Coalfield, Paran?? Basin.In terms of sequence stratigraphic interpretation the precursor mires of the Santa Catarina coal seams formed in an estuarine-barrier shoreface depositional environment, with major peat accumulation in a high stand systems tract (Pre-Bonito and Bonito seams), a lowstand systems tract (Ponta Alta seam, seam A, seam B) and a transgressive systems tract (Irapu??, Barro Branco and Treviso seams).Seam thicknesses range from 1.70 to 2.39. m, but high proportions of impure coal (coaly shale and shaley coal), carbonaceous shale and partings reduce the net coal thickness significantly. Coal lithoypes are variable, with banded coal predominant in the Barro Branco seam, and banded dull and dull coal predominantly in Bonito and Irapu?? seams, respectively. Results from petrographic analyses indicate a vitrinite reflectance range from 0.76 to 1.63 %Rrandom (HVB A to LVB coal). Maceral group distribution varies significantly, with the Barro Branco seam having the highest vitrinite content (mean 67.5 vol%), whereas the Irapu?? seam has the highest inertinite content (33.8. vol%). Liptinite mean values range from 7.8. vol% (Barro Branco seam) to 22.5. vol% (Irapu?? seam).Results from proximate analyses indicate for the three seams high ash yields (50.2 - 64.2wt.%). Considering the International Classification of in-Seam Coals, all samples are in fact classified as carbonaceous rocks (>50wt.% ash). Sulfur contents range from 3.4 to 7.7 wt.%, of which the major part occurs as pyritic sulfur. Results of X-ray diffraction indicate the

  3. Middle Proterozoic mafic magmatism, east central Idaho: Implications for age of deposition of Belt Supergroup and basin subsidence models

    SciTech Connect

    Chamberlain, K.R. . Dept. of Geology and Geophysics); Doughty, P.T. . Geological Sciences)

    1993-04-01

    In the Salmon River Arch, a ca. 1,365 Ma rapikivi granite intrudes the Proterozoic Yellow Jacket Formation, which is commonly correlated with the basal Belt-Purcell Supergroup. The contact aureole of the granite contains andalusite and overprints greenschist-facies burial metamorphism in the undeformed sedimentary strata. To the north, the granite intrudes amphibolite-facies, migmatitic paragneiss and a mafic igneous complex. Textures within the migmatites attest to deformation during partial melting. Preliminary U-Pb zircon data from a quartz diorite that intrudes the Yellowjacket sediments yield an age of ca. 1,445 Ma. This is consistent with zircon ages from the Crossport C and Moyie sills in northern Idaho and southern BC that constrain the basal Belt Supergroup to be older than 1,440 Ma. U-Pb zircon data from an amphibolitized mafic dike within the mafic igneous complex along the Salmon River are nearly concordant and yield Pb/Pb ages of ca. 1,377 Ma. The zircons exhibit skeletal, magmatic morphologies and the age is interpreted to be the time of primary crystallization. This age is slightly older than the age of the rapikivi granite and overlaps with the U-Pb zircon age of leucosomes in the migmatites. Thus, bimodal magmatism and partial melting occurred ca. 1,370 Ma. Deformation accompanied these events, but was concentrated in the deeper level, high-grade rocks. These processes are syn-depositional, based on age constraints from the intrusive quartz diorite. The authors envision that burial metamorphism, deformation, partial melting mafic magmatism and granite emplacement occurred during extensional deformation in the base of the Yellowjacket basin.

  4. 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.

  5. Geological and environmental controls on the change of eruptive style (phreatomagmatic to Strombolian-effusive) of Late Pleistocene El Caracol tuff cone and its comparison with adjacent volcanoes around the Zacapu basin (Michoacán, México)

    NASA Astrophysics Data System (ADS)

    Kshirsagar, Pooja; Siebe, Claus; Guilbaud, Marie Noëlle; Salinas, Sergio

    2016-05-01

    The 28,300 year BP (cal 32,300 BP) El Caracol tuff cone complex is one of the few phreatomagmatic volcanoes in the scoria-cone dominated Plio-Quaternary Michoacán-Guanajuato Volcanic Field (MGVF). It displays a shallow circular crater of ~ 1 km in diameter that is filled with several meter-thick lava flows and is located between two NE-SW trending normal faults dipping NW. It lies directly on top of Pliocene lavas of the San Lorenzo shield volcano that forms part of a tectonic horst (topographic high) separating the Zacapu lake basin (1980 m) in the south from the Río Angulo river valley (1760 m) to the north. Detailed study of the tephra sequence indicates that the eruption occurred in two stages: 1) Weak phreatomagmatic, in which about 0.1-0.5 km3 dense rock equivalent (DRE) of magma was issued within ~ 1 to 3 months at the rate of 4-40 m3/s, and 2) purely magmatic (Strombolian-effusive) during which the vent shifted slightly its position toward the NW, forming a small scoria cone (~ 100 m high) on the crater rim of the tuff cone. From this scoria cone lava flows were issued, first into the tuff cone crater occupying its bottom, and subsequently toward the NW, down the outer flank of the tuff cone and into the plain, where they reached a distance of ~ 3.5 km. During this stage ~ 0.6 km3 DRE of magma was produced at the rate of ~ 4 m3/s in a period of ~ 5 months. Although El Caracol displays many features that are characteristic for a phreatomagmatic vent, its morphology, types of deposits, and its complex process of formation makes it strikingly different from the more typical case of the ~ 21,000 year BP (cal 25,300 BP) Alberca de Guadalupe maar volcano, situated not far at the SE margin of the Zacapu basin. The latter was solely phreatomagmatic during the course of its eruption and is formed in its entirety by surge and fallout breccias consisting largely of xenolithic material. In contrast, at El Caracol the hydrogeological environment (namely the low

  6. 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.

  7. Event sedimentation in low-latitude deep-water carbonate basins, Anegada passage, northeast Caribbean

    USGS Publications Warehouse

    Chaytor, Jason D.; ten Brink, Uri S.

    2015-01-01

    The Virgin Islands and Whiting basins in the Northeast Caribbean are deep, structurally controlled depocentres partially bound by shallow-water carbonate platforms. Closed basins such as these are thought to document earthquake and hurricane events through the accumulation of event layers such as debris flow and turbidity current deposits and the internal deformation of deposited material. Event layers in the Virgin Islands and Whiting basins are predominantly thin and discontinuous, containing varying amounts of reef- and slope-derived material. Three turbidites/sandy intervals in the upper 2 m of sediment in the eastern Virgin Islands Basin were deposited between ca. 2000 and 13 600 years ago, but do not extend across the basin. In the central and western Virgin Islands Basin, a structureless clay-rich interval is interpreted to be a unifite. Within the Whiting Basin, several discontinuous turbidites and other sand-rich intervals are primarily deposited in base of slope fans. The youngest of these turbidites is ca. 2600 years old. Sediment accumulation in these basins is low (−1) for basin adjacent to carbonate platform, possibly due to limited sediment input during highstand sea-level conditions, sediment trapping and/or cohesive basin walls. We find no evidence of recent sediment transport (turbidites or debris flows) or sediment deformation that can be attributed to the ca. M7.2 1867 Virgin Islands earthquake whose epicentre was located on the north wall of the Virgin Islands Basin or to recent hurricanes that have impacted the region. The lack of significant appreciable pebble or greater size carbonate material in any of the available cores suggests that submarine landslide and basin-wide blocky debris flows have not been a significant mechanism of basin margin modification in the last several thousand years. Thus, basins such as those described here may be poor recorders of past natural hazards, but may provide a long-term record of past oceanographic

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  9. Depositional facies and sequence stratigraphy of a Lower Carboniferous bryozoan-crinoidal carbonate ramp in the Illinois Basin, mid-continent USA

    USGS Publications Warehouse

    Lasemi, Z.; Norby, R.D.; Treworgy, J.D.

    1998-01-01

    The Lower Carboniferous Fort Payne and Ullin Formations in the Illinois Basin form the transgressive and highstand systems tracts that were deposited in a carbonate ramp setting. During deposition of the Ullin Limestone, biotic communities dominated by fenestrate bryozoans and echinoderms (primarily crinoids) proliferated, possibly in response to global tectonic, biological, and oceanographic events that affected bathymetry and nutrient supply. The Fort Payne Formation consists of a dark grey-brown, siliceous and argillaceous lime mudstone in the lower part (transgressive systems tract) and a very fine-grained wackestone to packstone with rare mud mounds in the upper part (early high-stand), and was deposited in an outer ramp to basinal environment. During deposition of the lower Ullin Limestone (mostly early highstand), bryozoan-crinoidal build-ups accreted both laterally and vertically into several relatively large carbonate banks, which were partly surrounded by siliceous Fort Payne sea. Bryozoans (primarily fenestrates) were especially prevalent during the late stage of bank development and formed mud-free bioherms up to 120 m thick. In places, carbonate mud mounds also formed during the early stage of bank deposition. Bioherm development declined during deposition of the upper Ullin Limestone (late highstand), and a broad, storm-dominated carbonate ramp was established that became the site for widespread deposition of bryozoan-crinoidal sandwaves. Gradual shallowing led to ooid formation at the end of Ullin deposition. This sequence was terminated by a relative rise in sea level that resulted in deposition of the transgressive facies of the lower part of the overlying Salem Limestone. The depositional style and the nature of skeletal material of the Fort Payne and Ullin Formations are similar to those of cool-water carbonates. A deep-water setting along with upwelling of cool, nutrient-rich oceanic waters may have been responsible for the proliferation of

  10. Sequence stratigraphy and depositional systems of the paleocene submarine fans in the central North Sea: The evolution of a shelf-to-basin system

    SciTech Connect

    Reinsborough, B.C.; Galloway, W.E. )

    1993-09-01

    Slope/basin depositional systems consist of combinations of facies, including slump lobes; chute, flute, and channel fills; mounded turbidite lobes; sheet turbidites; low-density turbidite sheets and fills; hemipelagic drapes; and contourite mounds. Specific facies associations are determined by the nature (point source or linear source) and caliber (volume, grain size, sand:mud) of sediment supply to the slope. The extensive well-log, seismic, and core database was used to dissect the stratal and facies architecture of the Andrew depositional system and characterize a logical evolution of the sand-rich shelf-to-basin depositional systems tract. The andrew consists of upper and lower depositional units bounded by downlap terminations and high-gamma marker beds. The lower Andrew displays three distinct sand-rich lobes, delineated by isopach, sand percent, log motif, and seismic facies maps Proximal, mounded, sand-rich units disperse into unchannelized sheet turbidites in the basin. No extensive incised submarine valleys feed this unit, which is characterized by coarsening and thickening-upward log responses and hummocky to discontinuous reflectors. The upper Andrew downlaps the lower unit and a single, linear sediments source was centered in the Witch ground graben. The dispersal pattern and internal character suggest the upper unit is a proximal slope apron, downlapping and filling interlobe bathymetric lows of the underlying unit. Sharp-based, blocky/digitate log signatures, discontinuous chaotic reflectors, and coarse-grained sediment characterize this unit. The lower Andrew represents a structurally focused, sand-rich lobe complex, without associated incised canyons. The Andrew system evolved as the delta platform expanded onto the proximal fan, resulting in a linear sediment source spilling over the slope as a fringing slope apron.

  11. Late Pleistocene Paleohydrology of Willcox Basin, Southeastern Basin and Range from 14C-Chronostratigraphy, Sedimentology, Fauna, and Stable Isotopes of Wetland and Lake-Shoreline Deposits

    NASA Astrophysics Data System (ADS)

    Kowler, A.; Bright, J. E.; Quade, J.

    2014-12-01

    Fossil shorelines record the areal extent of past lake expansions in closed basins of arid regions worldwide, reflecting hydrologic balance changes from one lake cycle to the next. Paleo-lake records from the northern Great Basin indicate low to intermediate lake levels there during the last glacial maximum (LGM: ca. 23-19 Cal ka BP) relative to those reached during the subsequent Deglacial interval, particularly in response to Heinrich events and attendant collapse of the Atlantic Meridional Overturning Circulation (AMOC) during the Heinrich 1 (H1) stadial (ca. 17.5-14.6 Cal ka BP). Competing hypotheses about the causes of these cycles imply that southern Basin and Range paleo-lakes experienced lake-level maxima during the LGM, rendering shoreline chronologies from that region of paramount importance to understanding regional atmospheric dynamics during this critical climate transition. In southeastern Arizona, highstands of paleo-Lake Cochise overlapped with many highstands in the Great Basin, forming a composite beach ridge in Willcox Basin from ca. 17 to ca. 13 Cal ka BP. However, recent 14C dating of shells and carbonates within a calcareous mudstone unit (Unit 5) buried beneath the ridge constrain emplacement of Unit 5 to ca. 19 Cal ka BP; evidence from the faunal and stable isotopic composition of ostracode and gastropod assemblages reveals the mudstone's lacustrine origin. Given that similar mudstones in drained basins of the southern Great Basin are known to have formed in paleo-wetlands, our findings have large implications for detecting and constraining the timing of ancient lake cycles and wetland expansions in arid closed basins worldwide. With respect to paleoclimate, the Unit 5 lake cycle occurred in advance of H1 and formation of the beach ridge by ~2 millennia, whereas the beach ridge continued to form following the H1 stadial. This suggests that lake cycles associated with the terminal LGM, H1 stadial, Bolling-Allerod, and Younger Dryas climatic

  12. Hydrogeochemical data from an acidic deposition study at McDonalds Branch basin in the New Jersey Pinelands, 1983-86

    USGS Publications Warehouse

    Lord, D.G.; Barringer, J.L.; Johnsson, P.A.; Schuster, P.F.; Walker, R.L.; Fairchild, J.E.; Sroka, B.N.; Jacobsen, Eric

    1990-01-01

    Data from a 1983-86 acidic-deposition study at McDonalds Branch basin, a small (2.35-sq-mi) forested watershed in Lebanon State Forest, New Jersey include mineralogy of soil and depositional clays; physical and chemical analyses of soils; hydrologic measurements (precipitation and throughfall amounts, stream stage and discharge, and water-table altitudes); and water quality data from precipitation, throughfall, soil water, surface water, and groundwater. Site locations, collector designs, and well- construction data also are presented. The pH of bulk precipitation to McDonalds Branch basin over the sampling period (January 1985 to March 1986) ranged from 4.0 to 4.7, with a mean of approximately 4.3. Stream pH ranged from 3.2 to 4.8 and generally increased in a downstream direction. In general sulfate was the dominant anion throughout the basin. Aluminum concentrations commonly were elevated in surface and groundwaters, and were as high as 10,000 micrograms/L at one upstream site on McDonalds Branch. Dissolved organic carbon was an important component of stream waters in some locations and ranged in concentration from 1/1 to 37 mg/L. (USGS)

  13. Clay sized fraction and powdered whole-rock X-ray analyses from alluvial basin deposits in central and southern New Mexico

    USGS Publications Warehouse

    Anderholm, S.K.

    1985-01-01

    As part of the study of the water quality and geochemistry of Southwest Alluvial Basins (SWAB) in parts of Colorado, New Mexico, and Texas, which is a Regional Aquifer-System Analysis (RASA) program, whole rock x-ray analysis and clay-size fraction mineralogy (x-ray) analysis of selected samples from alluvial basin deposits were done to investigate the types of minerals and clay types present in the aquifers. This was done to determine the plausible minerals and clay types in the aquifers that may be reacting with groundwater and affecting the water quality. The purpose of this report is only to present the whole rock x-ray and clay-fraction mineralogy data. Nineteen surface samples or samples from outcrop of Tertiary and Quaternary alluvial basin deposits in the central and southern Rio Grande rift were collected and analyzed. The analysis of the samples consisted of grain size analysis, and clay-size fraction mineralogy and semiquantitative analysis of the relative abundance of different clay mineral groups present. (USGS)

  14. Sea level controls on the textural characteristics and depositional architecture of the Hueneme and associated submarine fan systems, Santa Monica Basin, California

    USGS Publications Warehouse

    Normark, W.R.; Piper, D.J.W.; Hiscott, R.N.

    1998-01-01

    Hueneme and Dume submarine fans in Santa Monica Basin consist of sandy channel and muddy levee facies on the upper fan. lenticular sand sheets on the middle fan. and thinly bedded turbidite and hemipelagic facies elsewhere. Fifteen widely correlatable key seismic reflections in high-resolution airgun and deep-towed boomer profiles subdivide the fan and basin deposits into time-slices that show different thickness and seismic-facies distributions, inferred to result from changes in Quaternary sea level and sediment supply. At times of low sea level, highly efficient turbidity currents generated by hyperpycnal flows or sediment failures at river deltas carry sand well out onto the middle-fan area. Thick, muddy flows formed rapidly prograding high levees mainly on the western (right-hand) side of three valleys that fed Hueneme fan at different times: the most recently active of the lowstand fan valleys. Hueneme fan valley, now heads in Hueneme Canyon. At times of high sea level, fans receive sand from submarine canyons that intercept littoral-drift cells and mixed sediment from earthquake-triggered slumps. Turbidity currents are confined to 'underfit' talweg channels in fan valleys and to steep, small, basin-margin fans like Dume fan. Mud is effectively separated from sand at high sea level and moves basinward across the shelf in plumes and in storm-generated lutite flows, contributing to a basin-floor blanket that is locally thicker than contemporary fan deposits and that onlaps older fans at the basin margin. The infilling of Santa Monica Basin has involved both fan and basin-floor aggradation accompanied by landward and basinward facies shifts. Progradation was restricted to the downslope growth of high muddy levees and the periodic basinward advance of the toe of the steeper and sandier Dume fan. Although the region is tectonically active, major sedimentation changes can be related to eustatic sea-level changes. The primary controls on facies shifts and fan growth

  15. Geological, mineralogical and geochemical characteristics of zeolite deposits associated with borates in the Bigadiç, Emet and Kirka Neogene lacustrine basins, western Turkey

    NASA Astrophysics Data System (ADS)

    Gündogdu, M. N.; Yalçin, H.; Temel, A.; Clauer, N.

    1996-09-01

    The Bigadiç, Emet and Kirka lacustrine basins of western Turkey may be considered as Tibet-type graben structures that were developed during the Miocene within the Izmir-Ankara suture zone complex. The volcanic-sedimentary successions of these basins are made up of mudstone, carbonate (limestone and dolomite) and detrital rocks, and also of crystal or vitric tuffs about 135 to 200 m thick. The Degirmenli (Bigadiç), Emirler (Bigadiç) Köpenez (Emet) and Karaören (Kirka) tuffs constituting the zeolite deposits are situated beneath four borate deposits (colemanite, ulexite, borax). The most abundant diagenetic silicate minerals are K- and Ca-clinoptilolites in the zeolite deposits, and Li-rich trioctahedral smectites (stevensite, saponite and hectorite) and K-feldspar in the borate deposits. In the Degirmenli, Emirler, Köpenez and Karaören deposits, the following diagenetic facies were developed from rhyolitic glasses rich in K and poor in Na: (glass+smectite), (K-clinoptilolite+opal-CT), (Ca-clinoptilolite+K-feldspar±analcime± quartz) and (K-feldspar+analcime+quartz). K-feldspar which is also rarely associated with phillipsite (Karaören) and heulandite (Degirmenli and Karaören), succeeds clinoptilolite and precedes analcime in these diagenetic facies where dioctahedral smectites, opal-CT and quartz are the latest minerals. No diagenetic transformations exist between clinoptilolite, K-feldspar and analcime that were formed directly from glass. The lateral facies distributions resulted from the differences in salinity and pH of pore water trapped during deposition of the tuffs, but vertical distributions in vitric tuffs seem to have been controlled by the glass/liquid ratio of the reacting system and the permeability or diffusion rate of alkali elements. The Bigadiç, Emet and Kirka zeolite deposits which were formed in saline basins rich in Ca and Mg ions, show similar chemical changes, i.e. loss of alkalis and gain in alkaline-earth elements that have taken

  16. Catastrophic flood sediments in Chryse Basin, Mars, and Quincy Basin, Washington: Application of sandar facies model

    NASA Astrophysics Data System (ADS)

    Rice, James W., Jr.; Edgett, Kenneth S.

    Viking visible and thermal infrared observations and terrestrial catastrophic flood deposits provide clues to identify the outflow channel sediments that went into Chryse Basin on Mars. On Earth, sandar (outwash plains formed by coalescence of many jökulhlaup floods) are described in terms of three laterally adjacent facies: proximal, midfan, and distal. The Missoula Flood sediments deposited in Quincy Basin, Washington, comprise a miniature analog of Chryse Basin. The terminology and general characteristics of the sandar facies model are applied to Quincy Basin, although the depositional environment and clast sizes are somewhat different (higher-energy flood, larger clasts, subaqueous rather than subaerial deposition). For example, the Ephrata Fan (a deposit of boulders, cobbles, and pebbles) forms the midfan facies analog; a downfan sandy deposit (reworked into a dune field) comprises the distal facies analog. In Chryse Basin the midfan is defined by a heterogeneous rocky (0-25%), intermediate-albedo (0.21-0.26), intermediate thermal inertia (260-460Jm-2s-0.5K-1) surface, while the distal facies has a low albedo (0.14-0.16) and higher thermal inertia (340-700Jm-2s-0.5K-1). The Chryse midfan unit has rocks and windblown dust exposed at the surface. The sand of the distal facies in Chryse/Acidalia is reworked by the wind, as in Quincy Basin. The Viking 1 and Mars Pathfinder landing sites are located on the midfan unit. Observations that can be made at the Mars Pathfinder site might help in reevaluating whether or not Viking 1 landed on outflow channel sediments.

  17. Slope-apron deposition in an ordovician arc-related setting: The Vuelta de Las Tolas Member (Suri Formation), Famatina Basin, northwest Argentina

    USGS Publications Warehouse

    Mangano, M.G.; Buatois, L.A.

    1997-01-01

    The Ordovician Suri Formation is part of the infill of the Famatina Basin of northwest Argentina, which formed in an active setting along the western margin of early Paleozoic Gondwana. The lower part of this formation, the Vuelta de Las Tolas Member, records sedimentation on a slope apron formed in an intra-arc basin situated on a flooded continental arc platform. The coincidence of a thick Arenig-Llanvirn sedimentary succession and volcanic-plutonic arc rocks suggests an extensional or transtensional arc setting, and is consistent with evidence of an extensional regime within the volcanic arc in the northern Puna region. The studied stratigraphic sections consist of volcanic rocks and six sedimentary facies. The facies can be clustered into four facies associations. Association 1, composed of facies A (laminated siltstones and mudstones) and B (massive mudstones and siltstones), is interpreted to have accumulated from silty-muddy high-and low-density turbidity currents and highly fluid, silty debris flows, with subsequent reworking by bottom currents, and to a lesser extent, hemipelagic suspension in an open-slope setting. Facies association 2 is dominated by facies C (current-rippled siltstones) strata. These deposits are interpreted to record overbank sedimentation from fine-grained turbidity currents. Facies E (matrix-supported volcanic breccias) interbedded with andesitic lava units comprises facies association 3. Deposition was contemporaneous with subaqueous volcanic activity, and accumulated from cohesive debris flows in a coarse-grained wedge at the base of slope. Facies association 4 is typified by facies D (vitric fine-grained sandstones and siltstones) and F (channelized and graded volcanic conglomerates and breccias) deposits. These strata commonly display thinning-and fining-upward trends, indicating sedimentation from highly-concentrated volcaniclastic turbidity currents in a channelized system. The general characteristics of these deposits of fresh

  18. Helicopter AFMAG (ZTEM) EM and magnetic results over sedimentary exhalative (SEDEX) lead-zinc deposits at Howard's Pass in Selwyn Basin, Yukon

    NASA Astrophysics Data System (ADS)

    Legault, Jean M.; Latrous, Ali; Zhao, Shengkai; Bournas, Nasreddine; Plastow, Geoffrey C.; Xue, Gabriel Guang

    2016-01-01

    In 2008, a regional scale 24,675 line-km survey covering a 25,000 km2 area (1 km line spacing) was flown in the Selwyn Basin. The survey footprint straddles east-central Yukon and overlaps into the western North-west Territories. In March 2013, Yukon Geological Survey purchased the survey data and, in November 2013, released the data publicly. The Selwyn Basin area is prospective for sedimentary exhalative (SEDEX)-style Pb-Zn-Ag mineralisation and the z-axis tipper electromagnetic (ZTEM) survey data provide insights into regional structures and plutons in the region. The survey overflew the Howard's Pass SEDEX deposits at the south-eastern edge of the Selwyn Basin survey area that hosts a ~250 million tonne resource with ~4.5% Zn and ~1.5% Pb. Airborne geophysics has not been extensively used in SEDEX exploration of the Selwyn Basin and the ZTEM survey is one of the few publicly available airborne audio-frequency magnetic (AFMAG) EM-magnetic datasets that offer the opportunity to study the deposit response at Howard's Pass in close detail. Rock physical properties indicate that the lowest resistivities are associated with the Road River Group that contains the Pb-Zn mineralised horizon at Howard's Pass, but also include graphitic shales in the same formation. Major NW-SE to ESE and minor NNW-SSE linear conductive trends correlate with known regional geologic, structural and inferred mineral trends that were previously not visible in magnetic results. At the deposit scale, a thin NW-SE trending conductive lineament extends along the > 37-km-long `Zinc Corridor' horizon at Howard's Pass, but must include both the Pb-Zn sulphide mineralisation deposit horizon as well as the surrounding graphitic black shales. 2D and 3D ZTEM inversions reveal zones of enhanced conductivity along strike and at depth that appear to correlate with the clustering of Pb-Zn deposits, which had not been previously noticed.

  19. Organic-geochemical characterization of sedimentary organic matter deposited during the Valanginian carbon isotope excursion (Vocontian Basin, SE France)

    NASA Astrophysics Data System (ADS)

    Kujau, Ariane; Heimhofer, Ulrich; Ostertag-Henning, Christian; Mutterlose, Jörg; Gréselle, Benjamin

    2010-05-01

    Terrestrial and marine sedimentary archives covering the Valanginian interval (136.8-133.9 Ma, Ogg et al., 2004) display a distinct positive delta13C-isotope excursion (CIE) of ~2.5 permil (Lini et al., 1992; Gröcke et al., 2005). The carbon isotope shift spans ~2.0 Ma and has been interpreted to reflect severe perturbations of the Early Cretaceous carbon cycle and paleoenvironmental conditions. According to different authors, the Valanginian CIE was accompanied by enhanced volcanic activity of the Paranà-Etendeka large igneous flood basalts, enhanced pCO2 (Lini et al., 1992; Weissert et al., 1998), widespread biocalcification crisis (Erba et al., 2004) and a distinct climatic cooling as evidenced by ice-rafted debris and glendonites from high-latitude sites. In addition, the positive CIE was assigned to be the result of an anoxic event, named the Weissert OAE (Erba et al., 2004). In this study, we investigate the composition and distribution of sedimentary organic matter (OM) deposited in a hemipelagic setting before, during, and after the Valanginian CIE. The aim of this study is to provide a detailed view on possible changes in OM deposition during a time of major paleoenvironmental and climatic stress. The chosen approach combines sedimentological and chemostratigraphical information (delta13Ccarb) with geochemical analysis of the bulk OM (incl. TOC, C/N, delta13Corg, Rock-Eval) and biomarker data. For this study, hemipelagic deposits located in the basinal part of the Vocontian Trough (SE France) covering the late Valanginian to early Hauterivian (Campylotoxus Zone to Radiatus Zone) (Gréselle 2007) have been sampled on a high resolution (sampling spacing of ~2/m). A total of three sections has been logged (La Charce, Vergol, Morenas), which consist of hemipelagic marl-limestone alternations and which allow for the construction of a composite succession. The delta13Ccarb values range between ~0.1 and 2.7 permil and show a characteristic stratigraphic trend

  20. Chronology and tectono-sedimentary evolution of the Upper Pliocene to Quaternary deposits of the lower Guadalquivir foreland basin, SW Spain

    NASA Astrophysics Data System (ADS)

    Salvany, Josep Maria; Larrasoaña, Juan Cruz; Mediavilla, Carlos; Rebollo, Ana

    2011-11-01

    This paper presents new litho, chrono and magnetostratigraphic data from cores of 23 exploratory boreholes drilled in the Abalario and marshlands areas of the lower Guadalquivir basin (the western sector of the Guadalquivir foreland basin, SW of Spain). The lithologic logs of these boreholes identify four main sedimentary formations, namely: Almonte Sand and Gravel, Lebrija Clay and Gravel, Marismas Clay and Abalario Sand, respectively interpreted as proximal-alluvial, distal-alluvial, alluvial-estuarine and aeolian. From radiocarbon and magnetostratigraphic data, these formations were dated as Upper Pliocene to Holocene. In the marshlands area, three main sedimentary sequences are present: an Upper Pliocene to Lower Pleistocene sequence of the Almonte and Lebrija (lower unit) formations, a Pleistocene sequence of the Lebrija (upper unit) and the lower Marismas formations, and a latest Pleistocene to present-day sequence of the upper Marismas Formation. The three sequences began as a rapid alluvial progradation on a previously eroded surface, and a subsequent alluvial retrogradation. In the third sequence, estuarine and marsh sediments accumulated on top of the alluvial sediments. The aeolian sands of the Abalario topographic high developed coeval to alluvial and estuarine sedimentation after the first alluvial progradation, and continuously until the present. Correlation with the surrounding areas show that the sequences are the result of the forebulge uplift of the northern margin of the basin (Sierra Morena) and the adjacent Neogene oldest sediments of their northern fringe, both form the main source area of the study formations. This uplift occurred simultaneous to the flexural subsidence (SSE tilting) of the southern part of the basin, where sedimentary aggradation dominated.

  1. Tectonosedimentary evolution of the Crotone basin, Italy: Implications for Calabrian Arc geodynamics

    SciTech Connect

    Smale, J.L. ); Rio, D. ); Thunell, R.C. )

    1990-05-01

    Analysis of outcrop, well, and offshore seismic data has allowed the Neogene tectonosedimentary evolution of an Ionian Sea satellite basin to be outlined. The Crotone basin contains a series of postorogenic sediments deposited since Serravallian time atop a complex nappe system emplaced in the early Miocene. The basin's evolution can be considered predominantly one of distension in a fore-arc setting punctuated by compressional events. The earliest sediments (middle-late Miocene) consist of conglomerates, marls, and evaporites infilling a rapidly subsiding basin. A basin-wide Messinian unconformity and associated intraformational folding mark the close of this sedimentary cycle. Reestablishment of marine conditions in the early Pliocene is documented by sediments which show a distinct color banding and apparent rhythmicity, which may represent the basin margin to lowermost Pliocene marl/limestone rhythmic couplets present in southern Calabria. A bounding unconformity surface of middle Pliocene age (3.0 Ma), which corresponds to a major northwest-southeast compressional event, closes this depositional sequence. The basin depocenter shifted markedly toward the southeast, and both chaotic and strong subparallel reflector seismic facies of wide-ranging thicknesses fill the depositional topography created during this tectonic episode. Basin subsidence decreases dramatically in the late Pliocene and cessates in response to basin margin uplift in the early Pleistocene. The chronostratigraphic hierarchy of these depositional sequences allows them to constrain the deformational history of the basin. In addition, similar depositional hierarchies in adjacent basins (i.e., Paola, Cefalu, and Tyrrhenian Sea) allow them to tie the stratigraphy and evolution of the Crotone basin to the geodynamic evolution of the Calabrian arc system.

  2. Allochthonous deep-water basin deposits of the western US: Implications for Paleozoic paleogeography and plate margin tectonics

    SciTech Connect

    Miller, E.L. . Geology Dept.)

    1993-04-01

    The stratigraphy and sedimentology of the lower Paleozoic Roberts Mts. and upper Paleozoic Golconda allochthons can be used to reconstruct their general paleogeographic setting in the Paleozoic. Basalt pillow lavas and radiolarian chert, were once considered straightforward evidence that the allochthons represented imbricated ocean crust formed at sites far removed from continental influences. Better stratigraphic definition, provenance studies and geochemistry of lavas now indicate that clastic components were derived from the continental shelf or interior and basalts in the Roberts Mountains allochthon were erupted in an intraplate setting through thinned continental crust (Madrid, 1987). Both in the earliest Mississippian and in the Late Permian, the Antler Basin (Roberts Mts.) and the Havallah Basin (Golconda) received proximal detritus from island arc sources to the west, immediately prior to closure of the basins by thrust-faulting. These data suggest that both systems of basins formed as marginal basins by rifting on the continental shelf (Antler Basin) and along the continental margin (Havallah Basin) and were flanked to the west by active island arcs at least during part of their history. As such, their stratigraphy provides a great deal of insight regarding tectonism along the western plate margin of North America during the Paleozoic.

  3. Seismic sequence stratigraphy and platform to basin reservoir structuring of Lower Cretaceous deposits in the Sidi Aïch-Majoura region (Central Tunisia)

    NASA Astrophysics Data System (ADS)

    Azaïez, Hajer; Bédir, Mourad; Tanfous, Dorra; Soussi, Mohamed

    2007-05-01

    In central Tunisia, Lower Cretaceous deposits represent carbonate and sandstone reservoir series that correspond to proven oil fields. The main problems for hydrocarbon exploration of these levels are their basin tectonic configuration and their sequence distribution in addition to the source rock availability. The Central Atlas of Tunisia is characterized by deep seated faults directed northeast-southwest, northwest-southeast and north-south. These faults limit inherited tectonic blocks and show intruded Triassic salt domes. Lower Cretaceous series outcropping in the region along the anticline flanks present platform deposits. The seismic interpretation has followed the Exxon methodologies in the 26th A.A.P.G. Memoir. The defined Lower Cretaceous seismic units were calibrated with petroleum well data and tied to stratigraphic sequences established by outcrop studies. This allows the subsurface identification of subsiding zones and thus sequence deposit distribution. Seismic mapping of these units boundary shows a structuring from a platform to basin blocks zones and helps to understand the hydrocarbon reservoir systems-tract and horizon distribution around these domains.

  4. Geology and ground-water features of salt springs, seeps, and plains in the Arkansas and Red River basins of western Oklahoma and adjacent parts of Kansas and Texas

    USGS Publications Warehouse

    Ward, P.E.

    1963-01-01

    The salt springs, seeps, and plains described in this report are in the Arkansas and Red River basins in western Oklahoma and adjacent areas in Kansas and Texas. The springs and seeps contribute significantly to the generally poor water quality of the rivers by bringing salt (HaCI) to the surface at an estimated daily rate of more than 8,000 tons. The region investigated is characterized by low hills and rolling plains. Many of the rivers are eroded 100 feet or more below the .surrounding upland surface and in places the valleys are bordered by steep bluffs. The alluvial plains of the major rivers are wide and the river channels are shallow and unstable. The flow of many surface streams is intermittent, especially in the western part of the area. All the natural salt-contributing areas studied are within the outcrop area of rocks of Permian age. The Permian rocks, commonly termed red beds, are composed principally of red and gray gypsiferous shale, siltstone, sandstone, gypsum, anhydrite, and dolomite. Many of the formations contain halite in the subsurface. The halite occurs mostly as discontinuous lenses in shale, although some of the thicker, more massive beds are extensive. It underlies the entire region studied at depths ranging from about 30 feet to more than 2,000 feet. The salt and associated strata show evidence of extensive removal of salt through solution by ground water. Although the salt generally occurs in relatively impervious shale small joints and fractures ,allow the passage of small quantities of water which dissolves the salt. Salt water occurs in the report area at depths ranging from less than 100 feet to more than 1,000 feet. Salt water occurs both as meteoric and connate, but the water emerging as salt springs is meteoric. Tritium analyses show that the age of the water from several springs is less than 20 years. The salt springs, seeps, and plains are confined to 13 local areas. The flow of the springs and seeps is small, but the chloride

  5. Shallow to deep-water deposition in a Cratonic basin: an example from the Proterozoic Penganga Group, Pranhita Godavari Valley, India

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, Joydip; Chaudhuri, Asru K.

    2003-03-01

    The unmetamorphosed Proterozoic succession dominated by deep-water lithographic limestone and shale in the western flank of the Pranhita-Godavari Valley is designated as the Penganga Group. The succession in different parts of the Valley includes the Pranhita Sandstone (25-400 m), the Chanda Limestone (300 m), and the Sat Nala Shale (>2000 m) in ascending order. The Pranhita Sandstone and the Chanda Limestone reveal considerable variations in the character of the stratal packages and depositional settings from Mancherial in the south to Adilabad in the north. The Sat Nala Shale in both southern and northern outcrop belts is completely devoid of sand. It is brown to purple in colour and resembles present-day deep-water mud deposits. In the Mancherial area, the Pranhita Sandstone consists of 25-400 m thick conglomerate, pebbly red arkose and quartzose sandstone succession of coastal alluvial fan to shallow shelf origin. The Chanda Limestone is micritic and locally includes interbedded lenses of cross-stratified quartzose sandstone in the lower part. The depositional milieu varies from shallow shelf to below wave base outer ramp carbonate platform. Around Adilabad, the Pranhita Sandstone (25 m) lacks the conglomerate-pebbly arkose association at the base and comprises only quartzose sandstone and shale of shoreface to muddy shelf settings. The Chanda Limestone is essentially micritic but, in contrast to the Mancherial area, includes several interbedded intervals of slope-related, autoclastic debris flow limestone conglomerates and calciturbidites, and represents deep, outer ramp to slope and basinal settings. A predominantly deep-water micritic limestone and deep-water shale succession suggests that the Penganga basin evolved to a vast, deep epicratonic sea connected to an open ocean. The absence of a coastal alluvial fan association at the lower part of the Pranhita Sandstone and presence of a slope to basinal association in the Chanda Limestone in the northern

  6. Long-term response of surface water acid neutralizing capacity in a central Appalachian (USA) river basin to declining acid deposition

    NASA Astrophysics Data System (ADS)

    Kline, Kathleen M.; Eshleman, Keith N.; Garlitz, James E.; U'Ren, Sarah H.

    2016-12-01

    Long-term changes in acid-base chemistry resulting from declining regional acid deposition were examined using data from repeating synoptic surveys conducted within the 275 km2 Upper Savage River Watershed (USRW) in western Maryland (USA); a randomly-selected set of 40 stream reaches was sampled 36 times between 1999 and 2014 to: (1) repeatedly characterize the acid-base status of the entire river basin; (2) determine whether an extensive network of streams of varying order has shown signs of recovery in acid neutralizing capacity (ANC); and (3) understand the key factors controlling the rate of ANC recovery across the river network. Several non-parametric analyses of trends (i.e., Mann Kendall Trend: MKT tests; and Regional Kendall Trend: RKT) in streamwater acid-base chemistry suggest that USRW has significantly responded to declining acid deposition during the study period; the two most robust, statistically significant trends were decreasing surface water SO42- (∼1.5 μeq L-1 yr-1) and NO3- (∼1 μeq L-1 yr-1) concentrations-consistent with observed downward trends in regional wet S and N deposition. Basin-wide decreasing trends in K+, Mg2+, and Ca2+ were also observed, while Na+ concentrations increased. Significant ANC recovery was observed in 10-20% of USRW stream reaches (depending on the p level used), but the magnitude of the trend relative to natural variability was apparently insufficient to allow detection of a basin-wide ANC trend using the RKT test. Watershed factors, such as forest disturbances and increased application of road deicing salts, appeared to contribute to substantial variability in concentrations of NO3- and Na+ in streams across the basin, but these factors did not affect our overall interpretation of the results as a systematic recovery of USRW from regional acidification. Methodologically, RKT appears to be a robust method for identifying basin-wide trends using synoptic data, but MKT results for individual systems should be

  7. Using Oxygen 17 to assess the importance of Atmospherically Deposited N in the riverine flux of nitrogen in the Neuse River Basin, NC

    NASA Astrophysics Data System (ADS)

    Showers, B.

    2002-12-01

    The environmental impacts of atmospherically deposited nitrogen (ADN) is now recognized to be an important component of the eutrophication of streams, lakes, estuaries and coastal waters. Nitrogen limited coastal waters make up 15 % of the global ocean, but account for half of the new global oceanic primary productivity. It has been estimated that ADN accounts for 10-50 % of the total external nitrogen load for these coastal ecosystems, and that river systems deliver a significant proportion of this ADN load from watersheds. In the Neuse River Basin, NC the ADN flux has been previously calculated to be 1236 mg per square meter per year. Using conservative watershed retention rate estimates suggest that 10-45 % of the total N reaching the river and transported to the estuary in this basin is from ADN. We have developed a CF IRMS analytical technique that combines the thermal decomposition procedure of Michalski et al (in press) with FMAT Gasbench automation to efficiently measure the Oxygen 17 of riverine nitrate. This will determine the importance of ADN in the riverine flux of nitrate. In the Neuse River basin the Nitrogen 15 and Oxygen 18 of nitrate are not positively correlated in the river main stem, indicating that denitrification is not a significant process for in stream consumption of nitrogen. High Oxygen 18 values of nitrate are observed in the small order creeks and streams, which could possibly indicate de-nitrification or the importance of atmospheric deposition. High Oxygen 17 values of riverine nitrate during moderate to low flow conditions after rainfall events in small urban streams suggest that atmospheric deposition and not denitrification is responsible for the elevated Oxygen 18 nitrate values in these areas. Oxygen 17 values of riverine nitrate in agricultural and wooded areas in the lower portion of the basin suggest that these landscapes retain ADN. This means that current landscape retention models overestimate the importance of the

  8. 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.