Preliminary geologic map of the Ervay Basin SW quadrangle, Natrona County, Wyoming

This mapping project was selected to better understand how structural processes in the Ervay Basin and Ervay Basin SW quadrangles have affected local and regional geologic features and contributed to the formation of the Rattlesnake Hills, Granite Mountains, and Wind River Basin. Study of the deformation processes helps to explain current oil and gas production and may possibly identify future development trends. New mapping also provides a base for interpretation related to other possible strategic mineral resources, including uranium, rare earth elements, and other economic minerals in the basin. A secondary goal was to identify the spatial and temporal relationships of coeval Tertiary volcanic flows and the Wagon Bed Formation. Radiometric dating and geochemical analyses conducted for this project helps clarify the history and extent of Rattlesnake Hills volcanism. Although multiple radiometric ages have been acquired in the general area (Pekarek and others, 1974; Peterman and Hildreth, 1978; Langstaff, 1995; Fruchey, 2002), no prior geochronology currently exists from the study area.