Mineral resources of the Blitzen River Wilderness Study Area, Harney County, Oregon

The Blitzen River Wilderness Study Area (OR-002-086E) is located along the western slope of Steens Mountain in southeastern Oregon. At the request of the U.S. Bureau of Land Management, the U.S. Geological Survey and U.S. Bureau of Mines conducted field studies of 21,658 acres of the Blitzen River Wilderness Study Area. In this report, the area studied is referred to as the "wilderness study area," or simply the "study area." Fieldwork was conducted by the U.S. Geological Survey during 1986 and 1987 and by the U.S. Bureau of Mines during 1986 to evaluate the identified mineral resources (known) and the mineral resource potential (undiscovered) of the study area. No mineral resources were identified in the study area. However, the study indicates moderate potential for geothermal energy resources along northwest-trending fault zones in the western part of the study area. The study area has no potential for oil and gas resources. Character and Setting The Blitzen River Wilderness Study Area is located along the west slope of Steens Mountain (fig. 1), 55 mi south of Burns, Oreg., and 35 mi northwest of Fields, Oreg. The study area ranges in elevation from 4,200 ft where the Donner und Blitzen River enters Blitzen Valley to 6,500 ft above sea level along the easternmost boundary. West of the study area, the lower slope of Steens Mountain forms a Manuscript approved for publication June 22, 1988. gentle west-tilted plateau that ends abruptly at Callow Rim along the east edge of Callow Valley. Ten miles east of the study area the upper slope rises more than 3,100 ft to the crest of Steens Mountain, 9,670 ft above sea level. Several northwest-flowing rivers and creeks have cut deep gorges into the plateau (fig.l). The Donner und Blitzen River is the largest river in the region and collects most of the tributary drainage on the west side of Steens Mountain. The river flows north through the western part of the study area into the Blitzen Valley (fig. 1). The oldest rocks exposed in the study area are basalt flows of middle Miocene age (11.2 to 16.6 million years before present, Ma; see appendixes for geologic time chart). The basalt flows that underlie the entire study area are overlain in the northern part by late Miocene rhyolite ash-flow tuff and basalt flows. Identified Resources No mines, claims, prospects, or mineralized zones were found, and no mineral or energy resources or occurrences were identified wilhin or adjacent to the study area. Mineral Resource Potential Hot springs issue from a northwest-trending fault zone 2 to 5 mi north of the study area. This same fault zone extends southeasl ihrough ihe western part of the study area. Areas along the fault zone and parallel fault zones have moderate potential for geothermal energy resources. The study area has no potential for oil and gas resources. Mineral Resources of the Blitzen River Wilderness Study Area, Harney County, Oregon D1