Interaction of subsurface brines with oxygenated meteoric water, Ray Point Uranium District, South Texas, USA

Studies of modern ground-water geochemistry demonstrate that fault-leaked saline fluids from depth are complexly interacting with shallow oxygenated meteoric waters in the vicinity of the Ray Point uranium deposits, South Texas, USA. Methane contained in the saline fluids provides a source of food for sulfate-reducing bacteria which produce isotopically light, aqueous sulfide. Partial oxidation of this sulfide is postulated to produce elemental sulfur which is a key reactant in the formation of marcasite (orthorhombic iron disulfide). Similar processes have operated in the past in association with formation of the Ray Point uranium deposits. (authors)