Abstract

The relation between uranium and groundwater in the sedimentary basins of the Rocky Mountain region is a function of the geologic history of the basins and the past groundwater flow systems and their hydrochemistry. Groundwater flows from an area of high potential (recharge) to an area of low potential (discharge). Along the regional flow path, from recharge to discharge areas, the following chemical facies will theoretically develop for a reasonably heterogenous silicate sediment: HCO, SO, Cl. Because uranium can be easily carried in solution as a carbonate complex it would likely be leached and transported in the bicarbonate groundwater facies and precipitated in the transition zone between the bicarbonate and sulfate facies, where a number of other chemical changes occur. The bicarbonate groundwater facies is generally associated with regional groundwater recharge areas; it follows that the likely location for uranium exploration is in these recharge areas. The groundwater and uranium geology in the Powder River Basin, Wyoming, supports this conclusion.