Erosional margins and patterns of subsidence in the late Paleozoic west Texas basin and adjoining basins of west Texas and New Mexico

Abstract

—The West Texas Basin is a complex late Paleozoic basin on the unstable craton. It is a composite of Early Pennsylvanian and Early Permian deformation and Early Pennsylvanian through late Permian subsidence. The postdeformational bowl of subsidence of the West Texas Basin is broadly similar to the subsidence of true intracratonic basins, such as the Michigan and Williston Basins. Unlike these basins, however, the present boundaries of the West Texas Basin do not follow or preserve the original limits of subsidence. The southern, western and to a lesser degree the eastern margins have been altered by pre-Albian uplift and erosion, assisted by Laramide and Tertiary uplift on the western margin. Only the northern margin is preserved, although it is complicated by the neighboring Anadarko Basin. The Pennsylvanian and Permian subsidence continued to the south and west of the preserved basin and probably connected with the Orogrande and Pedregosa Basins. This larger "Permian Basin" contains both the Central Basin axis and the Diablo-Pedernal axis as intrabasin tectonic belts. The post-Permian erosion was probably due to a combination of uplift on the flanks of the Triassic-Jurassic rift complex, which resulted in the opening of the Gulf of Mexico, and uplift on the flanks of the Early Cretaceous Bisbee–Chihuahua Trough. Reconnaissance subsidence analysis of the West Texas Basin discloses a complex pattern of subsidence rates through the Permian. The most rapid tectonic subsidence took place in the Wolfcampian of the southern Delaware Basin, between the Marathon thrust sheets and the Fort Stockton uplift. Flexural subsidence is probably responsible. Post-Wolfcampian (postdeformational) subsidence of unknown origin continued to be centered in the north-south Delaware Basin trough, but extended north and east over a broad area of the Central Basin axis, the Midland Basin and the Northwest shelf to form the "Permian Basin."