An Angular Unconformity between the Woodbine and Eagle Ford Formations in Delta, Hunt, and Hopkins Counties of the East Texas Basin

摘要

The East Texas Oil Field, one of the largest oil producing fields in the lower 48 (yielding approximately 5.2 billion dollars of oil since its discovery), comprises of a major structural trap created by the tectonically driven truncation of the Eagle Ford Group and much of the Woodbine Group by the Austin Chalk. This highlights the importance of regional tectonics on the depositional history of East Texas Basin during the Upper Cretaceous. From a dataset of wells centered around the Mexia-Talco Fault System in Rockwall, Collin, Hunt, Hopkins, and Delta counties of north Texas, we correlated 3rd order stratigraphic surfaces to get unit thicknesses. We observed a high-dip angular unconformity between the Woodbine and the Eagle Ford, which is more prominent across the northern flank of the Mexia-Talco Fault in Hopkins and Delta counties. We propose that the angular unconformity is evidence of the occurrence of a second Sabine Uplift between the Woodbine and Eagle Ford happening concurrently with a reactivation of the Mexia-Talco Fault and driven by Laramide tectonics and that the deposition of the Eagle Ford sediments occurred syndepositionally with uplift and related faulting.