National uranium resource evaluation, Hot Springs Quadrangle, South Dakota and Nebraska

The Hot Springs Quadrangle, South Dakota and Nebraska, was evaluated to a depth of 1500 m to identify environments and delineate areas favorable for the occurrence of uranium deposits. The evaluation used criteria developed by the National Uranium Resource Evaluation program. Surface reconnaissance was conducted using a portable scintillometer and a gamma spectrometer. Geochemical sampling was carried out in all geologic environments accessible within the quadrangle. Additional investigations included the followup of aerial radiometric and hydrogeochemical anomalies and a subsurface study. Environments favorable for sandstone-type deposits occur in the Inyan Kara Group and Chadron Member of the White River Group. Environments favorable for marine black-shale deposits occur in the Hayden Member of the Minnelusa Formation. A small area of the Harney Peak Granite is favorable for authigenic deposits. Environments considered unfavorable for uranium deposits are the Precambrian granitic and metasedimentary rocks and Paleozoic, Mesozoic, and Tertiary sedimentary rocks other than those previously mentioned.