Abstract

Cavernous porosity is well-developed throughout the Castile Formation outcrop area of the western Delaware Basin, including both epigene and hypogene caves. Epigene karst is widespread throughout the study area, while hypogene karst forms dense clusters of solutional caves and extensive zones of intrastratal brecciation. Masses and lateral sheets of calcitized evaporites are commonly associated with clusters of hypogene karst, as well as native sulfur mineralization and secondary selenite masses. This assemblage of sulfate alteration attests to a basin-scale system dominated by hypogene processes, where fluids, both water and hydrocarbon, derived from the underlying Delaware Mountain Group have largely controlled regional sulfate diagenesis. It appears that much of the hypogene diagenesis within the Castile Formation is related to multiple phases of fluid migration that occurred under higher geothermal gradients in the mid-Tertiary.