National Uranium Resource Evaluation Program. Hydrogeochemical and Stream Sediment Reconnaissance Basic Data for Lemmon NTMS Quadrangle, South Dakota

摘要

Results are reported of a reconnaissance geochemical survey of the Lemmon Quadrangle, South Dakota. Field and laboratory data are presented for 565 groundwater and 531 stream sediment samples. Statistical and areal distributions of uranium and possible uranium-related variables are displayed. A generalized geologic map of the survey area is provided, and pertinent geologic factors are briefly discussed which may be of significance in evaluating the potential for uranium mineralization. The groundwater data indicate that the area which appears most promising for uranium mineralization is located in the southwestern portion of the quadrangle. Groundwater in this area is produced primarily from the Cretaceous Fox Hills Formation where high values were determined for uranium, arsenic, potassium, and silicon and low values for boron, sodium, pH, sulfate, specific conductance, and total alkalinity. The presence of Tertiary ash deposits and the abundance of organics downdip in the permeable Fox Hills Formation could provide a suitable geochemical framework for uranium accumulation. The stream sediment data indicate that the Pierre Shale, Fox Hills, and Hell Creek Formations in the southwestern portion of the quadrangle have the highest potential for uranium mineralization. Sediments derived from these units are high in uranium, aluminum, arsenic, chromium, cobalt, copper, lithium, magnesium, niobium, nickel, phosphorous, scandium, vanadium, yttrium, zinc, and zirconium. (ERA citation 05:017418)