Abstract

The solution-mineral equilibria approach to groundwater geochemistry has been shown to be a useful regional exploration tool in the search for sandstone uranium deposits. A test of this technique in a 169-square mile area of South Texas has outlined areas with known mineralization or with a high potential for mineralization. This sophisticated technique should represent a significant improvement over previously used methods of interpreting groundwater geochemical data for exploration purposes, because the chemistry of all major cations is included in the calculations of mineral saturations.

Groundwaters can be collected from existing water wells over a large area and can be chemically analyzed at a relatively low cost. The chemical analyses are then used as input to the WATEQF computer program, which calculates the state of saturation of the groundwater with respect to many minerals.

Supersaturation maxima for coffinite, uraninite, and associated minerals such as smectite, delineate a highly prospective fairway in an area containing known uranium mineralization and downdip from the known mineralization. Field measurement of Eh has delineated the groundwater redox front, which in this case closely coincides with the redox front of the sediments.

Groundwater geochemistry provides a fast method to pinpoint the most prospective areas for an exploration drilling program. The WATEQF solution-mineral approach to groundwater geochemistry has a great potential to be used routinely in the exploration for mineral deposits.