Abstract

Wilshire field in the southwestern part of the Midland Basin, Permian Basin is characterized by a north-south trending fault system that formed during late Paleozoic time. This fault system is structurally parallel to the trend of the Central Basin Platform. This study examined the late Paleozoic stratigraphic and tectonic history of Wilshire field and adjacent area in order to constrain the timing of deformational events, the causes of the deformation, and the result and effects on late Paleozoic deposition in the southwestern Midland Basin.

Before Missouri-Virgil time, the study area was a tectonically stable region that was dominated by extensive shallow-water carbonate sedimentation. Soon after deposition of Strawn carbonate ramp facies, tectonic deformation occurred in the western and eastern parts of the study area. The eastern part of the study area is characterized by an asymmetric anticline that is cut by a basement-involved fault, whereas the western part is bounded by the uplifted Central Basin Platform, which is dominated by strike-slip style of deformation. The overlying upper Pennsylvanian through lower Leonardian interval represents a synorogenic sedimentary wedge that was largely sourced from the Central Basin Platform. The study area returned to tectonically stable conditions during development of lower Leonardian carbonate platforms, which built away from remnant structural highs that formed during previous phase of tectonic activity.

Differential erosion of the Strawn Formation in the western and eastern parts of the study area can help to estimate the structural relief across the study area and constrain the relative timing of late Paleozoic deformation events across the southwestern Midland Basin. Compared with the Central Basin Platform, the compressive structure at Wilshire field had a much lower structural relief. The deformational history of the Wilshire structure, which ended by late Pennsylvanian time, also was shorter than for the Central Basin Platform, where faulting and uplift mostly terminated by late Wolfcampian time. These relationships indicate that regional tectonic stress were responsible for deformation.