Uranium geology of Morton Ranch property, southern Powder River basin, Wyoming

The Morton Ranch uranium deposits are located along the southern axis of the Powder River basin approximately 22 mi (35 km) northwest of Douglas, Wyoming. The property encompasses approximately 26,000 acres (10,400 ha.) of private and state lands and is divided into two separate tracts: North Morton and South Morton. The uranium deposits are restricted to two bedrock units-Wasatch Formation (Eocene) and Fort Union Formation (Paleocene). Both rock units consist essentially of fluvial sediments of interbedded and highly lenticular silty claystone and sandy siltstones that contain lenses of coarse, cross-bedded, arkosic sandstone. Most of the uranium mineralization is restricted to three sandstone units within the Fort Union Formation. The ore sands are continuous throughout the area and range in thickness from 2 to 80 ft (0.6 to 24 m). On South Morton, the ore sands crop out in the Box Creek area but for the most part lie at a depth of 40 to 300 ft (12 to 90 m) below the surface. On North Morton, the ore sands are 550 to 700 ft (165 to 210 m) below the surface. The uranium orebodies are present typically as geochemical-cell or "roll-front" deposits. Of less importance are tabular and elliptical or dish-shaped orebodies, primarily present on South Morton. Surface (open pit) and possibly adit-level underground mines are planned for South Morton and underground mines for North Morton. In-situ leaching may be used as a recovery method in some areas of the property.