Mineral resources of the Black Ridge Canyons Wilderness Study Area, Mesa County, Colorado, and Grand County, Utah, and Westwater Canyon Wilderness Study Area, Grand County, Utah

Abstract

In 1986 the U.S. Bureau of Mines and the U.S. Geological Survey conducted studies to appraise the identified mineral resources (known) and assess the mineral resource potential (undiscovered) of 73,937 acres of the Black Ridge Canyons (CO-Q70-113/113A; UT-060-116/117) and 31,160 acres of the Westwater Canyon (UT-060-118) Wilderness Study Areas in western Colorado and eastern Utah. Subeconomic placer gold deposits were identified along the Colorado River at the Pussycat claims in the Westwater Canyon study area. Identified resources of dimension stone occur in the west-central part of the Black Ridge Canyons Wilderness Study Area. Subeconomic sand, gravel, stone, and rock resources occur within the Black Ridge Canyons study area, but sufficient quantities are available elsewhere to satisfy current needs. There is a high mineral resource potential for placer gold adjacent to the Colorado River and in terrace deposits above it in both study areas. There is a moderate resource potential for gold, silver, copper, and barite in vein deposits in the southern part of the Westwater Canyon Wilderness Study Area. There is also a moderate resource potential for uranium occurrences in the Morrison Formation in the southeastern part of Black Ridge Canyons Wilderness Study Area, but no resource potential for this type of uranium occurrence due to complete erosion of the Morrison Formation in the Westwater Canyon Wilderness Study Area. There is a low resource potential for gold, silver, mercury, copper, and uranium in the Chinle Formation in both study areas, and for chromium, nickel, and cobalt resources in Precambrian (Proterozoic; see geologic time chart in appendix) rocks in both study areas. Geological, geochemical, and geophysical studies indicate a low energy resource potential for undiscovered oil, natural gas, carbon dioxide, and geothermal energy in both study areas, and a low mineral resource potential for the above-mentioned mineral resources for both study areas where not specified differently. There is a low resource potential for coal in the Black Ridge Canyons Study Area, and no potential for coal in the Westwater Canyon Study Area. Character and Setting The wilderness study areas are located west of Grand Junction, Colo., on the northern and western flanks of the Uncompahgre Plateau (fig. 1). The study areas comprise 105,417 acres of desert canyons and mesas along the Colorado River in Mesa County, Colo., and Grand County, Utah. The entire area is underlain by over a thousand feet of nearly flat-lying Mesozoic (see geologic time chart in appendix) sedimentary rocks of the Chinle, Wingate, Kayenta, Entrada, Wanakah, Morrison, and Dakota Formations overlying Precambrian igneous and metamorphic rocks. The study areas are transected by several westnorthwest-trending normal faults and down-warped rocks. Identified Resources and Mineral Resource Potential There has been modest production of some commodities within the study areas. During the 1950's and 1960's, 7,000 short tons of flagstone were produced from a Black Ridge Canyons and Westwater Canyon Wilderness Study Areas C1 GARFIELD COUNTY MESA COUNTY HIGHLINE CANAL ASBURY