Mineral resources of the Nopah Range Wilderness Study Area, Inyo County, California

Abstract

At request of Bureau of Land Management, 109,061 acres of Nopah Range Wilderness Study Area (CDCA-150) were originally designated for study by U.S. Geological Survey and U.S. Bureau of Mines. Subsequently, in 1983, study area was decreased to current 97,151 acres. This report presents results of a mineral survey of part of Nopah Wilderness Study Area. In this report, area studied is referred to as the wilderness study or simply the study There has been little mining activity in region. Workings within and near wilderness study area consist of one mine, three prospects, and one zeolite occurrence, none of which has identified resources. Four localities within revised study area have mineral resource potential: (1) a 3-mi-long area on northwest side of Nopah Range with moderate resource potential for undiscovered silver, lead, and zinc resources; (2 and 3) two areas on southeastern side of study area have low resource potential for undiscovered silver and lead resources, and (4) an area on east-central side of range has low resource potential for gold, molybdenum, and lead resources. In southern part of Resting Spring Range west of study area, one area has low potential for copper and 2 areas have low potential for zeolite (clinoptilolite). The resource potential for copper is unknown within study area. The resource potential for borates and (or) zeolites in Chicago Valley is unknown. There are numerous limestone, quartzite, and sand and gravel deposits in study area. However, resource potential of these commodities is low. The mineral resource potential for oil and gas and geothermal energy is low in study area. Character and Setting The Nopah Range Wilderness Study Area is located in southeastern Inyo County, California, approximately 15 mi east of south end of Death Valley National Monument and 2 mi southwest of California-Nevada border (fig. 1). The study area lies within Basin and Range geomorphic province and encompasses most of Nopah Range, southernmost part of Resting Spring Range, and intervening part of Chicago Valley. The Nopah Range, underlain predominantly by carbonate rocks of Cambrian through Pennsylvanian (see geologic time chart in appendix) age, 570 to 290 million years before present (Ma), is characterized by deep canyons, ridges, and rugged topography; precipices of 1,000 ft or more are common. By contrast, southern part of Resting Spring Range, which is underlain predominantly by Late Proterozoic fine-grained terrigenous sedimentary rocks, is more subdued topographically. Minor amounts of volcanic rocks are present in both ranges. The flanks of ranges are marked by coalescing alluvial fans that merge with lacustrine deposits in surrounding valleys. Elevations in area range from 1,800 ft at south end of Chicago Valley to 6,394 ft on Nopah Peak. Mining activity in study area has been very limited, and only Nancy Ann mine (fig. 2) has a history of production.