Description: The McCoy geothermal system straddles the border of Lander and Churchill counties, central Nevada, in the middle of the Basin and Range Province. The study area occupies approximately 100 sq. km. near the intersection of the Augusta and Clan Alpine Mountains and the New Pass Range. The geology of the area is dominated by rhyolite ash-flow tuffs and subordinate intermediate-composition lava flows of Oligocene age. These volcanics were emplaced on Permo-Pennsylvanian massive cherts and Triassic dolomitic limestones. At least two episodes of hydrothermal activity can be recognized at McCoy. The oldest event altered and mineralized the volcanic and sedimentary rocks, producing the McCoy and Wild Horse mercury deposits. The youngest event produced travertine and siliceous sinter deposits which intercalate with alluvium, and appears to be related to the high heat flow found at the McCoy prospect. The oldest recognized faults at McCoy produced several east-west grabens and horsts. These fault zones were active before and during the deposition of the volcanics. The Wild Horse and McCoy mercury mines occur along one of these east-west fault zones. Basin and Range faulting began subsequent to 23 m.y. ago, and produced a complex array of polygonal blocks which were subsequently eroded into subparallel cuestas. Fluid movement in the geothermal system is controlled by the intersections of the east-west and north-south faults. There is no known igneous source for the thermal energy in this system. However, its intramontane location is atypical of known geothermal systems in the Basin and Range, which may preclude deep circulation through major basin-bounding faults.
Date: June 1, 1982
Creator: Adams, M. C.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department