Abstract

On the Diablo Plateau of West Texas, the Lower Permian Powwow Member of the Hueco Canyon Formation at the base of the Hueco Group rests on an angular unconformity above rocks that range in age from Proterozoic to early Wolfcampian. The Powwow Member is of nonmarine origin and is conformably overlain by limestones with the fusulinid Pseudoschwagerina and other fossils that indicate the Powwow is of middle Wolfcampian age. We demonstrate that outcrops at Reef Hill in the Hueco Mountains assigned by some previous workers to the Powwow Member are stratigraphically lower and older strata of early Wolfcampian age that are part of the Magdalena Formation. The Powwow Member thus is younger than and not equivalent to the lower Wolfcampian Bursum Formation of central New Mexico; instead, the Powwow Member is equivalent to the basal Abo Formation in central New Mexico. The Powwow Member identifies a significant regional tectonic event during the middle Wolfcampian that was a part of the Marathon-Ouachita orogeny and reflects synorogenic sedimentation coeval with the onset of deposition of the Abo Formation in central New Mexico.