Mineral resources of the Upper Deep Creek Wilderness Study Area, Owyhee County, Idaho

Abstract

The Upper Deep Creek Wilderness Study Area (ID-111-044) is located on the northern Owyhee Plateau in southwest Idaho and encompasses 11,510 acres, of which the U.S. Geological Survey and the U.S. Bureau of Mines were asked to 5,700 acres. Hereafter, the terms study and wilderness refer pnly to the smaller acreage. Field work for this report was conducted in 1985 to assess the identified mineral resources (known) and mineral resource potential (undiscovered) of the area. No mines, prospects, or claims are located in the area and there are no identified mineral or energy resources. The area has moderate resource potential for small gold placers and low potential for gold and silver resources in epithermal (hydrothermal) deposits. The area also has low potential for tin and uranium resources; the southern part has low potential for diatomite resources. The potential for oil, gas, and geothermal energy resources in the area is low. Character and Setting The Upper Deep Creek Wilderness Study Area is located on the northern Owyhee Plateau of southwest Idaho (fig. 1), about 80 mi southwest of Boise. The terrain is characterized by a stream-dissected plateau, averaging about 5,300 ft in elevation, with several prominent canyons, including the 200to 400-ft-deep canyon of Deep Creek that extends the length of the area. The surrounding Owyhee Plateau is underlain by a thick (greater than 800 ft) flat-lying sequence of Miocene (see appendix for geologic time chart) rhyolitic ash-flow tuffs, basalt flows, and minor interbedded sedimentary rocks. A thick rhyolitic ashflow tuff is exposed in most of the area; the tuff is overlain in the southern part by a sequence of thin basalt flows and basal sedimentary rocks (fig. 2). Geologic and geophysical data indicate that the area lies within a large collapsed caldera. The ashflow tuff and overlying units are interpreted to be part of a post-collapse sequence that has filled and buried most of the caldera. A small (0.5 by 0.25 mi) basalt maar crater (Indian Lake, fig. 2) is located directly east of the area. Identified Resources No mining claims were located and no minerals were produced in the area. There are no identified mineral or energy resources within the area. Mineral Resource Potential There is moderate resource potential for placer gold resources obtained by recreational, suctiondredge methods along the Deep Creek stream bed (fig. 2); relatively high concentrations of particulate gold were identified in sand and gravel bars along the creek within the area. The entire area has a low potential for gold and silver resources in epithermal deposits (fig. 2). This is indicated by weak, sporadic geochemical anomalies, and the presence of placer gold. Altered