Abstract

The most significant barite concentrations in Texas occur within Permian carbonate-evaporite strata of the Delaware Basin. The Seven Heart Gap deposit in south-central Culberson County along the northwestern flank of the Apache Mountains was the largest barite producer in Texas. The Delaware Basin also contains barite associated with elemental sulfur deposits in altered Ochoan carbonate and evaporite strata, including the Culberson (Rustler Springs) deposit, one of the largest commercial sulfur concentrations in the world. These elemental sulfur concentrations contain varying, but locally significant, amounts of barite and celestite.

Barite at Seven Heart Gap and within the sulfur deposits is replacive and pore-filling within evaporitic carbonate strata. Barite and sulfur deposits share many geological and geochemical features that result from a common geologic terrane. Fluid-inclusion and stable-isotope data for Delaware Basin barite occurrences, combined with published barite-solubility studies, suggest that the most likely mechanism for the formation of these barite concentrations was the mixing of barium-containing formational brines with sulfate-bearing solutions, probably of meteoric origin. Bacterial reduction of evaporite-derived sulfate and accompanying petroleum degradation is an important genetic aspect for the formation of the sulfur deposits and their hosting bacterogenic carbonates, but cannot be demonstrated for the Seven Heart Gap barite-hosting carbonates. Further, available geologic evidence indicates that the Seven Heart Gap barite concentrations are the result of older mineralization processes, perhaps as old as latest Permian, whereas barite concentrations accompanying sulfur mineralization within the Rustler Springs district are middle Miocene or younger.