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Research about Nevada

Source-linked reports with geographic coverage including Nevada.

At least 1,009 records · Page 56Linked to original sources
USGS1978

Potential sites for a spent unreprocessed fuel facility (SURFF), southwestern part of the Nevada Test Site

In the absence of specific criteria, the topography, geomorphology, and geology of Jackass Flats and vicinity in the southwestern part of the Nevada Test Site are evaluated by arbitrary guidelines for a Spent Unreprocessed Fuel Facility. The guidelines include requirements for surface slopes of less than 5 percent, 61 m of alluvium beneath the site, an area free of active erosion or deposition, lack of faults, a minimum area of 5 km2, no potential for flooding, and as many logistical support facilities as possible. The geology of the Jackass Flats area is similar to the rest of the Nevada Test Site in topographic relief (305-1,200 m), stratigraphy (complexly folded and faulted Paleozoic sediments overlain by Tertiary ash-flow tuffs and lavas overlain in turn by younger alluvium), and structure (Paleozoic thrust faults and folds, strike-slip faults, proximity to volcanic centers, and Basin and Range normal faults). Of the stratigraphic units at the potential Spent Unreprocessed Fuel Facility site in Jackass Flats, only the thickness and stability of the alluvium are of immediate importance. Basin and Range faults and a possible extension of the Mine Mountain fault need further investigation. The combination of a slope map and a simplified geologic and physiographic map into one map shows several potential sites for a Spent Unreprocessed Fuel Facility in Jackass Flats. The potential areas have slopes of less than 5 percent and contain only desert pavement or segmented desert pavement--the two physiographic categories having the greatest geomorphic and hydraulic stability. Before further work can be done, specific criteria for a Spent Unreprocessed Fuel Facility site must be defined. Following criteria definition, potential sites will require detailed topographic and geologic studies, subsurface investigations (including geophysical methods, trenching, and perhaps shallow drilling for faults in alluvium), detailed surface hydrologic studies, and possibly subsurface hydrologic studies.

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USGS1978

Fission-track dating of the Climax and Gold Meadows stocks, Nye County, Nevada

Fission-track ages indicate an age of 101 m.y. for the Climax stock and a minimum age of 93.6 m.y. for the Gold Meadows stock, both at the Nevada Test Site, Nye County, Nevada. Younger fission-track ages for apatite concentrates suggest that the stocks have been within 4 km of the surface since Late Paleocene time.

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USGS1978

Flood investigations in Nevada through 1977 water year

Maximum annual discharges, gage heights, and probable flood dates for 127 sites are compiled for Nevada streams. Data have been collected in cooperation with the Nevada Department of Highways at most of the sites (108). Also included in the report are the peak discharges, gage heights, and flood dates for the period of record at continuous recording gaging stations and a compilation of peak-flow measurements made at miscellaneous streamsites.

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USGS1978

Documentation of potential for surface faulting related to ground-water withdrawal in Las Vegas Valley, Nevada

Leveling data collected in Las Vegas Valley are compatible with the interpretation that ongoing land-surface displacements related to ground-water withdrawal may be precursory to fault offset of the land surface. Zones of potential faulting intersect regions of intense urban development. The degree of risk and the potential economic consequences from possible surface faulting cannot be assessed adequately without additional data and analysis of the relation between surface faulting and ground-water withdrawal.

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USGS1978

Principal facts for borehole gravity stations in test well Ue 19z, exploratory drill hole PM-1, and water well 5a, Nevada Test Site, Nye County, Nevada

During field studies conducted in October 1977 and March 1978, borehole gravity surveys were completed by the U.S. Geological Survey at the Nevada Test Site in test well Ue19z, exploratory drill hole PH-1, and water well 5a. The U.S. Geological Survey-LaCoste and Romberg-1/ borehole gravity meter (McCulloh and others, 1967a; McCulloh and others, 1967b) was used in the logging program. The primary objective of this work was to obtain data for the determination of accurate in situ formation densities utilizing an instrument not significantly affected by casing, borehole rugosity, or other near-borehole conditions. This report provides a brief summary of the geology of the rock formations penetrated by drill holes Ue 19z, PH-1, and water well 5a, and tabulates the subsurface gravity data obtained in these, wells. Reduced sections of the gamma-ray logs run in PM-1 and 5a are also included.

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USGS1978

Development of a relation for steady-state pumping rate for Eagle Valley ground-water basin, Nevada

Eagle Valley is a topographic and ground-water basin in the west-central area of Nevada. The demand for water in the valley is approaching the limits of the locally available resource, which is the water yield of 9,000 acre-feet per year from the adjacent mountain areas. The steady-state pumping rate from the ground-water basin is defined as the rate that just balances ground-water recharge and discharge. The recharge of water after agricultural or municipal use is a contribution toward overall ground-water recharge and, therefore, to the steady-state pumping rate. However, because the recharge factors are different for municipal and agricultural use, the total quantity of ground-water recharge from the beneficial use of water depends on the type of water use. Consequently, the steady-state pumping rate depends on the type of water use.

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USGS1978

Water resources data, Nevada, water years 1977

Water resources data for the 1977 water year for Nevada consist of records of discharge and water quality of streams; stage, contents, and water quality of lakes and reservoirs; and water levels in wells. This report contains discharge records for 120 gaging stations; stage and contents for 20 lakes and reservoirs; water-quality data for continuing-record stations at 27 stream sites and for partial-record stations at 8 stream sites, 2 lake sites, and 15 wells; and water levels for 165 observation wells. Also included are 106 crest-stage partial-record stations and 13 low-flow partial-record stations. Additional water data were collected at various sites, not part of the systematic data collection program, and are published as miscellaneous measurements. These data represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating State and Federal agencies in Nevada.

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USGS1978

Geometry and rates of change of fault-generated range fronts, north-central Nevada

Characteristic features of fault-generated range fronts, such as those on the Humboldt and Tobin Ranges, include sets of elongate basins extending normal to the range crest, interbasin spurs having crests sloping 10° to 20° toward the range front, spur facets having slopes of 25° to 35°, basin headwalls having slopes of 20° to 30°, and a basal fault scarp. The basal fault scarp is rejuvenated by vertical movements recurring at intervals on the order of 10 000 years. Fault scarps in colluvium that lie within a few tens of meters of the base of faceted spurs remain clearly recognizable for only a few tens of thousand years. Initial fault-scarp slopes of 50° to 90° are replaced by debris-controlled slopes of 30° to 37° within a few thousand years. In fractured bedrock, slope angles in the range of 25° to 35° remain relatively stable for hundreds of thousands of years and account for the relative stability of facets on spurs. Piedmont slopes are greatly affected by tectonic tilting or warping toward or away from the range front. The formation of pediments is believed to result from a low ratio of uplift relative to downcutting. A few million years is required for the development of a pediment a few kilometers wide.

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USGS1978

Age and composition of igneous rocks, Edna Mountain quadrangle, Humboldt County, Nevada

Six pulses of igneous activity ranging in age from Jurassic to Pliocene have been identified in the Edna Mountain quadrangle, Humboldt County, Nev. Porphyritic syenite am! quartz monzonite of Jurassic age (146-164 million years) at Buffalo Mountain are highly potassic through a wide range in SiO 2 content from olivine-bearing syenite to quartz-rich monzonite, and their composition contrasts sharply with plutons elsewhere in north-central Nevada. Granodiorite and quartz monzonite plutons of Cretaceous age (88- 106 m.y.) are chemically and mineralogically similar to other calc-alkaline plutons in north-central Nevada. Four episodes of Tertiary volcanism include rhyolite ashflow tuffs and slightly younger andesitic basalt flows and tuffs of Oligocene age, rhyolite vitrophyre of late Miocene age, and olivine basalt flows of Pliocene age. Their age and mineralogical and chemical compositions are similar to other Tertiary volcanic rocks in north-central Nevada.

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USGS1978

Uranium in waters and aquifer rocks at the Nevada Test Site, Nye County, Nevada

Previous chemical, geological, and hydrological information describing the physical and chemical environment of the Nevada Test Site (a Federal reserve for the testing of nuclear explosive devices) has been combined with new radiochemical and isotope data for water and rock samples in order to explain the behavior of uranium during alteration of thick sequences of rhyolitic volcanic rocks and associated volcaniclastic sediments. A model is proposed in which uranium mobility is controlled by two competing processes. Uranium is liberated from the volcanic rocks through dissolution of the glassy constituents and is carried in solution as a uranyl carbonate complex. Uranium is subsequently removed from solution by adsorption on secondary oxides of iron, titanium, and manganese, as observed in fission-track maps of aquifer rocks. The model explains the poor correlation of dissolved uranium with depth within tuffaceous sequences in which percolation of ground water is predominantly downward. Good positive correlation of dissolved uranium with dissolved Na, total dissolved solids, and total carbonate supports the glass dissolution model, while inverse correlation of dissolved uranium with U 234 /U 238 ratios of waters implies uranium is being absorbed by a relatively insoluble, surficial phase. Alpha radioactivity of Test Site water is primarily caused by high U 234 contents, and beta activity is highly correlated with dissolved K (K 40 ). Small amounts of dissolved radium, Pb 210 , and Po 210 are present but no evidence was found for alpha activity sources related to nuclear testing (Pu, U 235 ). A filtered but unacidified carbonate solution of uranium was found to be stable (± 10 percent of original U concentration) for years when stored in acid-washed polyethylene bottles.

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USGS1978

Chemistry of Tertiary volcanic rocks in the Eldorado Mountains, Clark County, Nevada, and comparisons with rocks from some nearby areas

Chemical variations of 27 rocks that erupted from in and near the Eldorado Mountains, southern Nevada, show (1) fair to good correlation suggestive of a cogenetic suite, (2) a range of uncorrected silica values from about 48 to 74 weight percent with no strong tendency toward bimodality, (3) a calc-alkaline characteristic, and (4) a shift from early eruptions having an anomalously low level of iron enrichment to later eruptions having a more normal level of iron enrichment. Analyses of rocks not known to have been erupted from the Eldorado Mountains (for example, five analyses of the tuff of Bridge Spring and two analyses of the Fortification Basalt Member of the Muddy Creek Formation) are not anomalous when compared with the other rocks, except that iron concentration in the Fortification Basalt Member may be higher than normal. Extensive K-Ar age data provide a clear time framework for the chemical changes as well as for the structural history of the area. The inception of intense extensional tectonism about 15 million years ago was marked by an abrupt shift to more iron-rich and more typically calc-alkalic volcanic products (Mount Davis Volcanics) than those erupted earlier (Patsy Mine Volcanics), but no corresponding shift in K 2 O or total alkali contents or ratios is recognized nor is there any obvious shift toward bimodality in rocks younger than 15 million years. These data, together with data from the Oatman district of Arizona, 100 kilometers to the south-southeast, indicate that the northern part of the lower Colorado River area does not fit into the published Cenozoic patterns of volcanic and tectonic evolution of the western United States. A brief review of nearby areas indicates that they may not fit well either.

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USGS1978

Stable isotope studies of bedded barite at East Northumberland Canyon in Toquima Range, central Nevada

Several beds of barite occur in the Slaven Chert at East Northumberland Canyon in the Toquima Range of central Nevada. Most of the barite is internally laminated but shows massive weathering. However, rosette, disseminated, conglomeratic, and concretionary varieties also occur. New fossil evidence from conodonts and brachiopods indicates a Late Devonian age for the Slaven Chert at East Northumberland Canyon. Preliminary δ 34 S values of most disseminated and massive-laminated barite within the Slaven Chert average about 25 permil; these are within the range of values that is typical of sulfate from Late Devonian seawater and are distinctly different from δ 34 S values of most crosscutting hydrothermal barite veins in the area. Primary δ 34 S values of the bedded barite appear to be retained during recrystallization and hydrothermal alteration, suggesting that δ 34 S data of bedded barites could be developed into a useful stratigraphic tool. The δ 34 S values of rosette and concrectionary barites range from 29.1 to 56.3 permil and indicate that these varieties of barite formed in restricted microenvironments where extensive bacterial reduction of seawater sulfate occurred. The δ 18 O data on cherts associated with the barite beds and δ 14 C and δ 18 O data on carbonate beds within the Slaven Chert indicate that the depositional environment at tames had restricted communication with normal seawater of the open ocean.

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