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R. C. Greene

Publications and source records attributed to R. C. Greene.

10 recordsLinked to original sources
USGS1981

Location of a Caldera Source for the Soldier Meadow Tuff, Northwestern Nevada, Indicated by Gravity and Aeromagnetic Data

The Soldier Meadow Tuff in north-western Nevada is part of a sequence of peralkaline and subalkaline rhyolitic rocks of Miocene age that occupies an area of about 1,600 km 2 and has a volume of about 50 km 3 . The formation is mostly welded tuff containing abundant alkali feldspar and quartz phenocrysts in devitrified groundmass containing minute needles of blue-green alkali amphibole. The rhyolite of Badger Mountain is similar in mineralogy and chemistry, but textures suggest that it is a flow rhyolite. The underlying rhyolite of Catnip Mountain and tuff of Trough Mountain are phenocryst-poor but apparently also peralkaline. Gravity and aeromagnetic anomaly maps show 16- by 24-km anomalies near Badger Mountain. An analysis of these maps suggests that observed anomalies could be caused by a concealed caldera of 2,700-m thickness filled with rocks 0.2 g/cm 3 less dense and 0***002 emu/cm 3 lower magnetic susceptibility than the surrounding rocks. Distribution of the Soldier Meadow Tuff and the occurrence of numerous vents in the rhyolite of Badger Mountain suggest that the source for both units is associated with the indicated caldera. Possible alternative sources are other calderas whose locations are suggested by a 7- by 11-km gravity minimum near Rock Spring Table and a 12- by 24-km magnetic minimum west of Soldier Meadow.

Nevada↗
USGS1978

Mineral resources of the Charles Sheldon wilderness study area, Humboldt and Washoe Counties, Nevada, and Lake and Harney Counties, Oregon

A mineral survey of the Charles Sheldon wilderness study area, located in Humboldt and Washoe Counties, Nevada, and Lake and Harney Counties, Oregon was conducted in 1974 and 1975 (fig. 1A, 1B, 1C). The mineral resource potential was evaluated by geological, geochemical, and geophysical studies by the U.S. Geological Survey, and by the examination of mines, prospects, and other mineralized localities by the U.S. Bureau of Mines. The investigation identified several areas of significant mineral potential within the study area which includes the Charles Sheldon Antelope Range and the Sheldon National Antelope Refuge (fig. 1B). The Virgin Valley area contains reserves of precious opal, small quantities of decorative building stone, and low-grade uranium resources. The investigation indicates that there are several areas of potential for the discovery at depth of mercury and for base and complex precious metal sulfide deposits within the study area. Reservoir temperatures, estimated from the analysis of thermal springs, suggest that the area has low-to-moderate potential for geothermal resources. The potential for oil, gas, or coal is very low.

Nevada, Oregon↗