Assessment of Undiscovered Sandstone-Hosted Uranium Resources in the Texas Coastal Plain - 2015

Uranium (Nuclear Minerals) / Exploration, Mining, Marketing, & Acquisitions

Mihalasky, and 7 team members, reported in 2015 that the U.S. Geological Survey (USGS) completed an assessment of undiscovered uranium resources hosted by Tertiary (Paleocene) sedimentary sequences of the Texas Coastal Plain. These deposits are found in sandstones, which are the most prolific uranium deposits in the United States. Deposits in the Texas Coastal Plain region are estimated to contain the third largest domestic sandstone-hosted
uranium resource after the Colorado Plateau and Wyoming Basin regions.

Estimates of undiscovered uranium resources associated with sandstone-hosted deposits in the Texas Coastal Plain were made for geologic units with known uranium occurrences: the Eocene Claiborne and Jackson Groups, the Oligocene Catahoula Formation, the Miocene Oakville Sandstone, the Pliocene Goliad Sand and Willis Formation, and the Pleistocene Lissie Formation (fig. 1). Sandstone facies that host mineralization were deposited in mixed marine-coastal-fluvial facies (Claiborne and Jackson Groups) and by dominantly fluvial systems (Catahoula Formation, Oakville Sandstone, Goliad Sand, Willis and Lissie Formations).

Uranium exploration is active throughout the region, and the Goliad Sand is host to two operating, in situ recovery mines, Alta Mesa and La Palangana. Geologic sedimentary units known to host uranium deposits were used to delineate three permissive tracts:

1) the Claiborne-Jackson tract,
2) the Catahoula-Oakville tract, and
3) the Goliad-Willis-Lissie tract.

The tracts group stratigraphic sequences that were deposited in broadly similar depositional environments. The tracts were geographically subdivided into the Rio Grande Embayment sub-tract (the southwestern region with more known occurrences and higher mineral potential) and the Houston Embayment sub-tract (the northeastern region with less known occurrences and lower mineral potential), forming a total of six sub-tracts. Within each sub-tract, undiscovered resources were assessed to a depth of 1,500 feet (~450 meters).

Although most uranium mining has taken place at depths less than 800 feet (~240 meters), economic deposits have been identified to depths of more than 1,200 feet (~365 meters); therefore, 1,500 feet (~450 meters) is the practical depth for the purposes of uranium mineral resource assessment in the region at this time.