THE SUBSIDENCE EVOLUTION OF THE PALEOZOIC FORT WORTH BASIN IN NORTH-CENTRAL TEXAS, USA

The Fort Worth basin in north-central Texas is one of the several foreland basins associated with the late Paleozoic Ouachita-Marathon orogeny that formed due to the oblique collision of the Afro-South American and North American continents. Though the Ouachita fold-and-thrust belt bounding the basin to the east is the major regional structure, the basin is also bounded by several other arches and uplifts to the other directions, which add complexity to the subsidence mechanism and tectonic evolution of the Fort Worth basin. Current studies to the Fort Worth basin focus mainly on Barnett Shale, however, understandings to the tectonic evolution of the basin are very limited. In this study, we reconstruct the subsidence history of the basin and constrain its dynamic relationship to the Ouachita fold-and-thrust belt – by constructing 1D tectonic subsidence curves, and modeling 2D flexure subsidence along cross sections. Because the Mesozoic strata have been eroded in the region, which adds uncertainty to the reconstruction of subsidence, we use Petromod 1D to model the burial history of the basin in order to reconstruct the depositional thickness of the Mesozoic strata. The reconstruction is achieved by matching the modeled vitrinite reflectance with measured vitrinite reflectance along depth profile in the basin. Our results improve the understanding to the tectonic history of the Fort Worth basin, and illustrate that the basin was mainly caused by flexure subsidence due to the uplift of the Ouachita fold-and-thrust belt during the late Paleozoic.