Late Paleozoic foreland deformation in the southwestern Midland Basin and adjacent areas: Implications for tectonic evolution of the Permian Basin, west Texas

The southwestern Midland Basin is located at the junction of several important late Paleozoic tectonic features within the Permian Basin, including the Central Basin Platform (CBP), Ozona Arch, and several basement-involved fault systems that partition the southwestern Midland Basin into smaller depocenters. These tectonic features formed far inboard of the Marathon fold-and-thrust belt. This study examined the late Paleozoic stratigraphic and structural characteristics of the southwestern Midland Basin and adjacent areas in order to constrain the timing of deformational events, the cause of the deformation, and document late Paleozoic tectonic history of the Permian Basin.; Three stages of deformation can be recognized based on significant changes in the lithofacies distribution, the style of deformation, and the area of active deformation through time. Before late Mississippian time, the study area was a tectonically stable region that was dominated by extensive shallow-water carbonate sedimentation. Minor en echelon folding reflected the initial, regionally distributed right-lateral strike-slip deformation in late Mississippian-middle Pennsylvanian time. Soon after deposition of Strawn carbonate ramp facies during a middle Pennsylvanian phase of relative tectonic quiescence, renewed and amplified right-lateral convergence enhanced structural relief of en echelon asymmetrical faulted anticlines. During late Pennsylvanian-Wolfcampian time, en echelon folding and faulting in the basin diminished, but right-lateral convergence continued and was mostly accommodated along the eastern boundary of the CBP as oblique-slip deformation, which is characterized by steeply dipping reverse faults and asymmetrical flower structures. Major uplift of the CBP occurred during this last phase of intraforeland deformation and the CBP served as the source for the wedge-shaped upper Pennsylvanian through Wolfcampian synorogenic periplatform deposits. The whole area returned to tectonically stable conditions during development of Leonardian carbonate platforms, which built away from the CBP that formed during previous phases of tectonic activity.; The tectonic relationships between subtle structures in the Midland Basin and the CBP are examples of the sequential development of structures during progressive transpressional deformation across a foreland basin. This study may provide insight into the origins of similar intraforeland basement uplifts that developed elsewhere across the interior of North America during late Paleozoic time.