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At least 1,603 records · Page 89Linked to original sources
USGS2016

Seasonal patterns in carbon dioxide in 15 mid-continent (USA) reservoirs

Evidence suggests that lakes are important sites for atmospheric CO 2 exchange and so play a substantial role in the global carbon budget. Previous research has 2 weaknesses: (1) most data have been collected only during the open-water or summer seasons, and (2) data are concentrated principally on natural lakes in northern latitudes. Here, we report on the full annual cycle of atmospheric CO 2 exchanges of 15 oligotrophic to eutrophic reservoirs in the Glacial Till Plains of the United States. With one exception, these reservoirs showed an overall loss of CO 2 during the year, with most values within the lower range reported for temperate lakes. There was a strong cross-system seasonal pattern: an average of 70% of total annual CO 2 efflux occurred by the end of spring mixis; some 20% of annual flux was reabsorbed during summer stratification; and the remaining 50% of efflux was lost during autumnal mixing. Net annual flux was negatively correlated with depth and positively correlated with both water residence time and DOC, with the smallest annual CO 2 efflux measured in shallow fertile impoundments. Strong correlations yield relationships allowing regional up-scaling of CO 2 evasion. Understanding lacustrine CO 2 uptake and evasion requires seasonal analyses across the full range of lake trophic states and morphometric attributes.

Missouri↗
USGS1990

Characterization of carbon in sediment-hosted disseminated gold deposits, north central Nevada

The gray, dark gray and black colors of the sediments and the presence of pyrite in the Carlin, Jerritt Canyon, Horse Canyon, Betze, and Gold Acres sediment-hosted disseminated gold (SHDG) deposits indicate that these rocks are not oxidized with respect to carbon and iron sulfide. The organic matter in the host rocks of SHDG deposits in north-central Nevada is cryptocrystalline graphite with dimensions of 30 to 70 A (0.003 to 0.007 ??) that was formed at temperatures of 250 to 300??C. These results indicate that north-central Nevada was subjected to pumpellyite-actinolite to lowermost greenschist facies conditions prior to mineralization. The hydrothermal fluids that produced the gold deposits had little, if any, effect on the thermal maturity and crystallinity of the cryptocrystalline graphite produced by the earlier thermal event.

Conference Paper↗
USGS1990

Oxygen and carbon isotope ratios of hydrothermal minerals from Yellowstone drill cores

Oxygen and carbon isotope ratios were measured for hydrothermal minerals (silica, clay and calcite) from fractures and vugs in altered rhyolite, located between 28 and 129 m below surface (in situ temperatures ranging from 81 to 199??C) in Yellowstone drill holes. The purpose of this study was to investigate the mechanism of formation of these minerals. The ??18O values of the thirty-two analyzed silica samples (quartz, chalcedony, ??-cristobalite, and ??-cristobalite) range from -7.5 to +2.8???. About one third of the silica 7samples have ??18O values that are consistent with isotopic equilibrium with present thermal waters; most of the other silica samples appear to have precipitated from water enriched in 18O (up to 4.7???) relative to present thermal water, assuming precipitation at present in situ temperatures. Available data on fluid-inclusion homogenization temperatures in hydrothermal quartz indicate that silica precipitation occurred mostly at temperatures above those measured during drilling and imply that 15O enrichments in water during silica precipitation were generally larger than those estimated from present conditions. Similarly, clay minerals (celadonite and smectite) have ??18O values higher (by 3.5 to 7.9???) than equilibrium values under present conditions. In contrast, all eight analyzed calcite samples are close to isotopic equilibrium with present thermal waters. The frequent incidence of apparent 18O enrichment in thermal water from which the hydrothermal minerals precipitated may indicate that a higher proportion of strongly 18O-enriched deep hydrothermal fluid once circulated through shallow portions of the Yellowstone system, or that a recurring transient 18O-enrichment effect occurs at shallow depths and is caused either by sudden decompressional boiling or by isotopic exchange at low water/rock ratios in new fractures. The mineralogy and apparent 18O enrichments of hydrothermal fracture-filling minerals are consistent with deposition during transient boiling or rock-water exchange (fracturing) events. ?? 1990.

Journal of Volcanology and Geothermal Research↗
USGS1998

Method determines vuggy carbonate permeability

An improved method determines vuggy carbonate permeability on the basis of specific surface area per unit pore volume and a flow zone indicator (FZI). Comparisons of fit standard error estimates show that this approach is superior to the multivariable empirical correlations of Chilingarian, et al., and to the ANN-estimated permeabilities.

Oil & Gas Journal↗
USGS2000

Distribution of surficial sediment in Long Island Sound and adjacent waters: Texture and total organic carbon

The surficial sediment distribution within Long Island Sound has been mapped and described using bottom samples, photography, and sidescan sonar, combined with information from the geologic literature. The distributions of sediment type and total organic carbon (TOC) reveal several broad trends that are largely related to the sea-floor geology, the bathymetry, and the effects of modern tidal- and wind-driven currents. Sediment types are most heterogeneous in bathymetrically complex and shallow nearshore areas; the heterogeneity diminishes and the texture fines with decreasing bottom-current energy. Lag deposits of gravel and gravelly sand dominate the surficial sediment texture in areas where bottom currents are the strongest (such as where tidal flow is constricted) and where glacial till crops out at the sea floor. Sand is the dominant sediment type in areas characterized by active sediment transport and in shallow areas affected by fine-grained winnowing. Silty sand and sand-silt-clay mark transitions within the basin from higher- to lower-energy environments, suggesting a diminished hydraulic ability to sort and transport sediment. Clayey silt and silty clay are the dominant sediment types accumulating in the central and western basins and in other areas characterized by long-term depositional environments. The amount of TOC in the sediments of Long Island Sound varies inversely with sediment grain size. Concentrations average more than 1.9% (dry weight) in clayey silt, but are less than 0.4% in sand. Generally, values for TOC increase both toward the west in the Sound and from the shallow margins to the deeper parts of the basin floor. Our data also suggest that TOC concentrations can vary seasonally.

Long Island Sound↗
USGS2003

Vegetation sensitivity to global anthropogenic carbon dioxide emissions in a topographically complex region

Anthropogenic increases in atmospheric carbon dioxide (CO2) concentrations may affect vegetation distribution both directly through changes in photosynthesis and water-use efficiency, and indirectly through CO2-induced climate change. Using an equilibrium vegetation model (BIOME4) driven by a regional climate model (RegCM2.5), we tested the sensitivity of vegetation in the western United States, a topographically complex region, to the direct, indirect, and combined effects of doubled preindustrial atmospheric CO2 concentrations. Those sensitivities were quantified using the kappa statistic. Simulated vegetation in the western United States was sensitive to changes in atmospheric CO2 concentrations, with woody biome types replacing less woody types throughout the domain. The simulated vegetation was also sensitive to climatic effects, particularly at high elevations, due to both warming throughout the domain and decreased precipitation in key mountain regions such as the Sierra Nevada of California and the Cascade and Blue Mountains of Oregon. Significantly, when the direct effects of CO2 on vegetation were tested in combination with the indirect effects of CO2-induced climate change, new vegetation patterns were created that were not seen in either of the individual cases. This result indicates that climatic and nonclimatic effects must be considered in tandem when assessing the potential impacts of elevated CO2 levels.

Global Biogeochemical Cycles↗
USGS2005

Adsorption in single-walled carbon nanotubes by experiments and molecular simulation II: Effect of morphology and temperature on organic adsorption

Hexane adsorption on single-walled carbon nanotube (SWNT) bundles was studied. Hexane adsorption capacities of two purified SWNT samples was gravimetrically determined at isothermal conditions of 25??, 37??, and 50??C for 10-4 < p/po < 0.9, where p/po is hexane vapor pressure relative to its saturation pressure. Simulation of hexane adsorption under similar temperature and pressure conditions were performed on the external and internal sites of nanotube bundles of diameters same as those in experimental samples. The simulations could predict isotherms for a hypothetical scenario where all nanotubes in a sample would be open. This is an abstract of a paper presented at the AIChE Annual Meeting and Fall Showcase (Cincinnati, OH 10/30/2005-11/4/2005).

Conference Paper↗
USGS2005

Euthanasia of neonatal mice with carbon dioxide

Exposure to carbon dioxide (CO2) is the most prevalent method used to euthanize rodents in biomedical research. The purpose of this study was to determine the time of CO2 exposure required to euthanize neonatal mice (0 to 10 days old). Multiple groups of mice were exposed to 100% CO 2 for time periods between 5 and 60 min. Mice were placed in room air for 10 or 20 min after CO2 exposure, to allow for the chance of recovery. If mice recovered at one time point, a longer exposure was examined. Inbred and outbred mice were compared. Results of the study indicated that time to death varied with the age of the animals and could be as long as 50 min on the day of birth and differed between inbred and outbred mice. Institutions euthanizing neonatal mice with CO2 may wish to adjust their CO 2 exposure time periods according the age of the mice and their genetic background. Copyright 2005 by the American Association for Laboratory Animal Science.

Comparative Medicine↗
USGS2009

Geochemistry and geochronology of carbonate-hosted base metal deposits in the southern Brooks Range, Alaska: Temporal association with VMS deposits and metallogenic implications

The Brooks Range contains enormous accumulations of zinc and copper, either as VMS or sediment-hosted deposits. The Ruby Creek and Omar deposits are Cu-Co stratabound deposits associated with dolomitic breccias. Numerous volcanogenic Cu-Zn (+/-Ag, Au) deposits are situated ~20 km north of the Ruby Creek deposit. The carbonate-hosted deposits consist of chalcopyrite and bornite that fill open spaces, replace the matrix of the breccias, and occur in later cross-cutting veins. Cobaltiferous pyrite, chalcocite, minor tennantite-tetrahedrite, galena, and sphalerite are also present. At Ruby Creek, phases such as carrollite, renierite, and germanite occur rarely. The deposits have undergone post-depositional metamorphism (Ruby Creek, low greenschist facies; Omar, blueschist facies). The unusual geochemical signature includes Cu-Co +/- Ag, As, Au, Bi, Ge, Hg, Sb, and U with sporadic high Re concentrations (up to 2.7 ppm). New Re-Os data were obtained for chalcopyrite, bornite, and pyrite from the Ruby Creek deposit (analyses of sulfides from Omar are in progress). The data show extremely high Re abundances (hundreds of ppb, low ppm) and contain essentially no common Os. The Re-Os data provide the first absolute ages of ore formation for the Ruby Creek deposit and demonstrate that the Re-Os systematics of pyrite, chalcopyrite, and bornite are unaffected by greenschist metamorphism. The Re-Os data show that the main phase of Cu mineralization occurred at 384 +/-4.2 Ma, which coincides with zircon U-Pb ages from igneous rocks that are spatially and genetically associated with VMS deposits. This suggests a temporal link between regional magmatism and hydrothermal mineralization.

Alaska↗
USGS1973

Dolomitization model for Upper Cambrian and Lower Ordovician carbonate rocks in the eastern United States

Existing models for dolomitization emphasize that penecontemporaneous dolomitization can occur in both subtidal and supratidal environments if the necessary chemical and physical factors favorable for the development of magnesium-rich hypersaline waters exist. Holocene shallow-water hypersaline environments that have the potential to produce dolomite without deposition of more soluble evaporite minerals are found in Shark Bay, Australia, and on the Great Bahama Bank. These hypersalinity systems are characterized by near-vertical isosalinity layers of increasing concentration landward from the open ocean and show little or no relationship to bottom topography. I suggest that a similar but larger scale epicontinentalsalinity system covering the Late Cambrian and Early Ordovician carbonate continental shelf produced a broad wedge of subtidally deposited dolomite in the eastern half of the United States from Mexico to Canada. The distribution of limestone and dolomite in this region is closely keyed to the salinity gradient and accounts for the natural progression from a normal marine limestone facies through a transition zone to a highly saline dolomite facies phase. Algal stromatolite mats and domes occupied low-energy niches in both the limestone and dolomite facies, whereas stratiform algal stromatolites were confined to the areas of moderate energy within the dolomite facies.

Journal of Research of the U.S. Geological Survey↗
USGS1991

Time-courses in the retention of food material in the bivalves Potamocorbula amurensis and Macoma balthica significance to the absorption of carbon and chromium

Time courses for ingestion, retention and release via feces of microbial food was investigated using 2 bivalves with different feeding strategies, Potamocorbula amurensis and Macoma balthica . The results showed 2 pathways for the uptake of food material in these clams. The first is represented by an initial label pulse in the feces. The second pathway operates over longer time periods. Inert 51 Cr-labeled beads were used to determine time frames for these pathways. The first pathway, involving extracellular digestion and intestinal uptake, is relatively inefficient in the digestion of bacterial cells by P. amurensis but more efficient in M. balthica . The second pathway, involving intracellular digestion within the digestive gland of both clams, was highly efficient in absorbing bacterial carbon, and was responsible for most chromium uptake. Differences in the overall retention of microbial 51 Cr and 14 C relate not to gut-passage times but to the processing and release strategies of the food material by these 2 clams.

Marine Ecology Progress Series↗
USGS2007

Assessment of marine-derived nutrients in the Copper River Delta, Alaska, using natural abundance of the stable isotopes of nitrogen, sulfur, and carbon

We performed nitrogen, sulfur, and carbon stable isotope analysis (SIA) on maturing and juvenile anadromous sockeye and coho salmon, and periphyton in two Copper River delta watersheds of Alaska to trace salmonderived nutrients during 2003&ndash;2004. Maturing salmon were isotopically enriched relative to alternate freshwater N, S, and C sources as expected, with differences consistent with species trophic level differences, and minor system, sex, and year-to-year differences, enabling use of SIA to trace these salmon-derived nutrients. Periphyton naturally colonized, incubated, and collected using Wildco Periphtyon Samplers in and near spawning sites was 34 S- and 15 N-enriched, as expected, and at all freshwater sites was 13 C-depleted. At nonspawning and coho-only sites, periphyton 34 S and 15 N was generally low. However, 34 S was low enough at some sites to be suggestive of sulfate reduction, complicating the use of S isotopes. Juvenile salmon SIA ranged in values consistent with using production derived from re-mineralization as well as direct utilization, but only by a minority fraction of coho salmon. Dependency on salmon-derived nutrients ranged from relatively high to relatively low, suggesting a space-limited system. No one particular isotope was found to be superior for determining the relative importance of salmon-derived nutrients.

American Fisheries Society Symposium↗
USGS1999

Hydrology and geochemistry of carbonate springs in Mantua Valley, northern Utah

Water chemistry, tritium data, precipitation-discharge relations, geology, topography, and dye tracing were used to determine recharge areas, ground-water residence times, factors influencing ground-water flow, and aquifer characteristic for five springs that discharge from Paleozoic limestones and dolostones along the margin of Manuta Valley, northern Utah. Temperature of Mantua Valley spring water ranged between 6.0 and 15.0 degrees Celsius. Spring-water temperature indicates that depth of circulation of ground water could be as shallow as 80 feet (25 meters) to as much as 1,150 feet (350 meters). Dissolved-solids concentration in the water from springs ranged from 176 to 268 milligrams per liter. Average total hardness of spring water ranged from 157 to 211 milligrams per liter. Water from all of the springs is a calcium-magnesium-bicarbonate type that generally is undersaturated with respect to calcite and dolomite. The molar calcium/magnesium ratio in spring water ranged from 1.21 to 1.88, and indicates that ground water flows through impure dolostone or a mixed limestone and dolostone terrace. Discharge from carbonate springs in Mantua Valley ranges from about to 10 to 4,300 gallons per minute (0.6 to 271 liters per second). Seasonal variations in chemical parameters and discharge indicate that the aquifers supplying water to most of these springs are predominantly diffuse-flow systems that have been locally enhanced by bedrock dissolution. Estimated recharge area for th springs ranges from 2.7 to 7 square miles (7 to 18 square kilometers). On the basis of tritium age dating, the mean residence time of ground water discharges from Olsens-West Hallins and Maple Springs was determined to be from 3 to 9, and from 4 to 15 years, respectively. Dye tracing from point sources 2.65 miles (4.26 kilometers) southeast of Maple Spring, however, indicates a substantially faster component of flow during snowmelt runoff, with a travel time of about 5 days, or an average ground-water velocity of about 2,700 feet per day (823 meters per day).

Utah↗
USGS1992

Correlation of pre-Carboniferous carbonate successions of northern Alaska

Fault-bounded successions of pre-Carboniferous (meta)carbonate rocks occur throughout northern Alaska. Successions studied in detail are those in the York Mountains (Seward Peninsula), the western and eastern Baird Mountains (western Brooks Range), the Snowden Mountain area (central Brooks Range), and the Sublik and Sadlerochit Mountains (eastern Brooks range); they are correlated on the basis of the lithofacies and conodont biostratigraphy. Available lithologic and biogeographic data are best explained by postulating that these successions accumulated on a single continental margin or platform that had faunal exchange with both Siberia and North America, rather than on a series of discrete platforms juxtaposed by later tectonic events.

Alaska↗
USGS2019

Carbon dioxide enhanced oil recovery and residual oil zone studies at the U.S. Geological Survey

The U.S. Geological Survey (USGS) is preparing a national resource assessment of the potential hydrocarbons recoverable after injection of carbon dioxide (CO2) into conventional oil reservoirs in the United States. The implementation of CO2-enhanced oil recovery (CO2-EOR) techniques can increase hydrocarbon production, and lead to incidental retention of CO2 in reservoir pore space allowing long-term storage of anthropogenic CO2. A Comprehensive Resource Database (CRD) containing proprietary data on location, geologic, petrophysical, and reservoir parameters, plus production and well counts for major oil and gas reservoirs in onshore areas and State waters of the conterminous United States and Alaska, was developed to support the USGS assessment. Residual oil zones (ROZs) also can provide potential pore space for long-term storage of anthropogenic CO2. However, ROZs are not included in the upcoming USGS national CO2-EOR assessment because assessment methods for ROZs still are being developed. Additional ROZ CO2-EOR and CO2 retention data and reservoir simulations are needed to calibrate national ROZ assessment estimates.

Conference Paper↗
USGS1974

Geology and mineral resources of the Lehighton and Palmerton quadrangles, Carbon and Northampton Counties, Pennsylvania

The Lehighton and Palmerton 73 1/2-minute quadrangles cover an area of about 112 square miles of diversified terrain in the folded Appalachian Mountain and Great Valley sections of the Valley and Ridge physiographic province in Carbon, Lehigh, and Northampton Counties, Pennsylvania. The Lehigh River and Blue Mountain are the prominent features of the topography. Rock units defined and mapped in the area are the lithified sediments that were deposited in a variety of offshore marine, marine shelf, marginal marine, and fluvial environments associated with two phases of basin filling. The rocks are separated into four lithotectonic units, each deformed semi-independently of adjacent lithotectonic units. Decollements presumably separate the lithotectonic units. Lithotectonic unit 1 consists of about 12,000 feet of slate and graywacke of the Middle and Upper Ordovician Martinsburg Formation. This unit contains mainly asymmetric, similar, and nearly isoclinal folds, with wave lengths of 1,000 to 3,000 feet and amplitudes of 400 to 2,000 feet, formed mainly by passive flow and slip. Lithotectonic unit 2 includes about 3,100 feet of sandstone, siltstone, shale, and conglomerate of the Shawangunk Formation (Ordovician(?) and Silurian), Bloomsburg Red Beds (Silurian), and the lower part of the Poxono Island Formation (Silurian). This unit contains mainly asymmetric and concentric folds, with wavelengths of about one mile and amplitudes of 1,500 to 5,000 feet, formed by flexural slip with minor passive slip and flow. Lithotectonic unit 3 contains about 750 feet of limestone, shale, siltstone, sandstone, and dolomite of the upper part of the Poxono Island Formation, Bossardville Limestone, and Decker Formation (all Silurian), the Coeymans and New Scotland Formations, Shriver Chert, and Ridgeley Formation of the Oriskany Group and the Schoharie-Esopus Formation (all Lower Devonian), and the Palmerton Formation and Buttermilk Falls Limestone (both Middle Devonian). This unit has asymmetric, concentric, similar, and flap folds, with wavelengths of 1,000 to 1,500 feet and amplitudes of about 1,550 feet, formed by flexural slip and flow and passive slip and flow. Lithotectonic unit 4 consists of more than 13,000 feet of sandstone, conglomerate, siltstone, and shale of the Middle Devonian Marcellus and Mahantango Formations, the Upper Devonian Trimmers Rock and Catskill Formations, the Devonian-Mississippian Spechty Kopf Forma tion, the Mississippian Pocono and Mauch Chunk Formations, and the Pennsylvanian Pottsville Formation. This unit contains nearly symmetric, concentric flexural-slip folds with wavelengths of more than five miles and amplitudes of about one mile. Surficial deposits occur throughout the mapped area and include: Pleistocene pre-lllinoian(?) till and outwash(?), lllinoian(?) till and outwash, Wisconsinan outwash, shale-chip rubble, boulder fields, and colluvium; and Holocene alluvium, landslide deposits, and man-made dumps. The rocks of the mapped area, except for the deeply weathered lime stones, generally have good slope stability and foundation support strength, moderate to low primary infiltration capacity and aquifer potential but moderate to high secondary values for these properties, moderate resistance to weathering, and are moderately difficult to difficult to excavate. All of these properties are strongly influenced by the abundant bedding, cleavage, and joint partings of the rocks. Similar evaluations for the surficial deposits indicate less desirable values except for the ease of excavation of most of the unconsolidated materials. Currently active and potential mineral resources are numerous in the Lehighton and Palmerton quadrangles and include slate, sand, paint ore, building stone, crushed rock, lightweight aggregate, clinker residue, clay, hydraulic cement, and roofing granules.

Pennsylvania↗
USGS1974

Thermal conductimetric determination of submilligram amounts of total water in silicate and carbonate minerals

A simple and rapid method was developed for determining sub milligram amounts of total water in silicate and carbonate minerals. Powdered samples are fused by heating with sodium tungstate vanadium pentoxide flux in a Vycor combustion tube, and the evolved water vapor is absorbed on silica gel. After the water collection, the silica gel is heated at a controlled rate, and the released water vapor, carried by helium, is detected by thermal conductivity.

Journal of Research of the U.S. Geological Survey↗
USGS1976

Brannerite from the Penn Haven Junction uranium occurrence, Carbon County, Pennsylvania

Thorium-free brannerite has been identified in Upper Devonian uraniferous sandstone from Penn Haven Junction, Carbon County, Pa. The brannerite was located by a variation of the "Lexan" technique and is associated with galena, uraninite, and clausthalite. The angular thorium-free nature of the brannerite suggests that it formed by metamorphism of uranium-saturated leucoxene. As a result of the metamorphism some uranium may be in less soluble minerals than those found in the uranium deposits of the Western United States. For this reason, in-place leaching of the uranium may be impractical.

Pennsylvania↗