Geology of the Roosevelt Hot Springs Area, Beaver County, Utah

Abstract

In the Roosevelt Hot Springs area on the western flank of the Mineral Range, Beaver County, Utah, Precambrian metamorphic rocks (principally biotite gneiss), Tertiary granite of the Mineral Range pluton, and late Pliocene or Pleistocene silicic volcanic rocks protrude through an extensive, westward sloping apron of alluvial fan deposits. North-trending faults are present in the foothills of the Mineral Range. Another conspicuous north-trending fault, the Dome fault, offsets Pleistocene(?) siliceous hot-spring deposits. Roosevelt Hot Springs, which no longer flow, were near the Dome fault. North and northeast-trending faults that produced small displacements in the alluvial fan surface were mapped in the central and western parts of the Roosevelt area. East-trending faults may also be present. Temperature gradients as high as 26.8°F per 100 feet have been reported. Steam was discharged from one well in 1968 and from another in 1975. The silica geothermometer and the sodium-potassium-calcium geothermometer were applied to published analyses of Roosevelt Hot Springs water; the silica geothermometer indicated reservoir temperatures of 210° and 195°C, and the Na-K-Ca geothermometer gave temperatures of 298° and 292°C.