Geology topics
Source-linked reports with geographic coverage including Nevada.
Bidirectional reflection spectra were recorded from samples selected from the NASA MSS Site 021 in the Shoshone Range, Nevada, by Gary Prost of the Superior Oil Co., Houston, Texas.
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No abstract available.
The Horse Spring Formation of Miocene age in Clark County, Nevada, contains as much as 0.5% Li in individual samples. Rock sequences which average 0.1% Li range from 3 m thick near Gold Butte (south of Mesquite, Nev.) to as much as 40 m thick near Lava Butte (east of Las Vegas, Nev.) about 75 km to the west. The lithium-bearing beds are light colored to white and contain hectorite in a dolomite, magnesite, or calcite matrix. Varied amounts of gypsum, halite, celestite, clinoptilolite, quartz, feldspar, biolite and colemanite are also present locally. Hectorite is the only lithium mineral recognized to date. The lithium-rich rocks contain low concentrations of most other minor elements except that boron and strontium are enriched. Rarely, barium, arsenic, and zinc are present in anomalously large amounts. The lithium-enriched part of the Horse Spring Formation was formed from a series of volcanic ashes which were deposited in a playa. Relict volcanic ash is recognizable in thin sections as remnant glass shards and vitroclastic textures. Most of the original glass has been altered to clay minerals, carbonate minerals, or zeolites, presumably through interaction with highly saline pore waters. Abundant evidence of spring activity suggests that thermal waters played a part in releasing the lithium from volcanic materials.
This study describes gonadal changes in lizards ( Uta stansburiana ) exposed to chronic low levels of γ radiation (1.5-10 R/day) under field conditions and attempts to evaluate endocrine involvement in these changes. Reproductive impairment in irradiated males is demonstrated during the breeding season by reduced testes weights and by seminiferous tubules devoid of germ cells. Ultrastructural morphology of Leydig cells, plasma testosterone levels, and developed accessory sex structures indicate normal steroidogenesis in such males; cytology of the pituitary gonadotropes and pituitary gonadotropin content indicate normal gonadotropin levels. These findings suggest that low levels of radiation affect the spermatogenic process directly, rather than through damage to the pituitary. Comparable irradiation causes complete resorption of ovarian tissue in some female Uta . The oviducts are atrophic and the pituitary gonadotropes hyperactive. Resemblance of gonadotropes to those of castrated animals and reduced pituitary hormone content suggest elevated levels of gonadotropin production, probably due to the absence of ovarian steroid feedback in affected animals. The continued mitotic activity of oogonia in adult reptiles and their limited number contribute to the vulnerability of germinal tissue in irradiated female lizards. Destruction of the germ cells is accompanied by resorption of all ovarian tissue including steroidogenic elements. Thus, in females as in males, radiation appears to damage gametogenesis rather than pituitary function.
Numerous and widespread subbituminous and lignite coal deposits occur in the Powder River Basin in southeastern Montana, principally within the Fort Union Formation. Many of the coal beds are less than 250 feet (76.2 m) below land surface and are, therefore, mineable by surface methods. Individual cola beds are commonly 20-30 feet (6.1-9.1 m) thick, but may be as much as 80 feet (24 m). These factors, coupled with the low-sulfur content of the coal, make it attractive as a major energy resource.
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No abstract available.
During July 1977, forty-nine gravity stations were obtained in the Double Hot Springs Known Geothermal Resource Area and vicinity, northwestern Nevada. Elevations for twenty-two stations were estimated from lake bed topographic contours. Horizontal positions for these stations were determined from topographic maps and vehicle odometer. Elevations for stations DBLD34 and DBLD35 were determined with altimeters. Positions for the remaining stations were taken from spot elevations shown on U.S. Geological Survey topographic maps at scales of 1:24,000.
During July 1977, fifty-one gravity stations were obtained in the Gerlach Extension Known Geothermal Resource Area and vicinity, northwestern Nevada. Elevations for twenty-seven stations were estimated from lake bed topographic contours. Horizontal positions for these stations were determined from topographic maps and vehicle odometer.
During July 1977, forty-four gravity stations were obtained in the Fly Ranch Extension Known-Geothermal Resource Area and vicinity, northwestern Nevada. Elevations for three stations were estimated from lake bed topographic contours. Horizontal and vertical positions for stations FREX33 through FREX43 were determined from plane-table surveying. Positions for the remaining stations were taken from benchmarks or spot elevations shown on U.S. Geological Survey topographic maps at scales of 1:24,000.
In August of 1976, borehole gravity surveys were conducted by the U.S. Geological Survey at the Nevada Test Site in the Ue10j, Ue7ns, and Ue5n test wells. The work was done in cooperation with the Lawrence Livermore Laboratory. The U.S. Geological Survey-LaCoste and Romberg borehole gravity meter was used in the logging program (McCulloh and others, 1967a; McCulloh and others, 1967b). The primary objective of this work was to obtain data for the determination of in situ formation densities utilizing an instrument not significantly affected by casing, borehole rugosity, or other near-borehole conditions. A secondary objective was to obtain duplicate data, by reoccupying subsurface stations, so that the precision and repeatability of borehole gravity data could be studied.