Evidence for Strike-Slip Faulting in the Smackover Formation of Northeast Texas and South Arkansas and Its Geological Implications

Abstract

ABSTRACT Surface expression, seismic profiles, gravity and magnetic mapping, and well control provide evidence for strike-slip faulting in the Smackover Formation of East Texas and South Arkansas. The faulting that occurred after the deposition of Smackover and during the deposition of Buckner Anhydrite appears to be an extension of the South Florida shear zone. Evidence includes drainage patterns; lineaments on Lansat imagery; seismic lines with flower structure fault patterns; magnetic data with ridges broken by right lateral offsets; and well log correlations with abrupt termination of horizons. The strike-slip faulting triggered significant geological events. The faulting breached the mountains and highlands surrounding the ancient Gulf, initiating the drainage systems that subsequently filled the basin. Fault breaks in the Buckner allowed meteoric water to reach the Louann Salt causing dissolution initiating the development of salt basin structure. Early diagenetic events in the Smackover involving fabric selective dissolution and dolomitization also began with the water incursion. Convergent movement along the strike of the fault created basement rock structure. Pre-existing basement structures were truncated and offset. However complex, there is still predictability in the system, the structures will occur along the trace of the fault. Although a strike-slip fault interpretation is a new concept in this region, the option has economic importance, and as more complete subsurface data becomes available, the concept can be tested.