The Late Paleozoic Subsidence Evolution of the Fort Worth Basin in North Central Texas, USA

Abstract

The Fort Worth Basin in north-central Texas is a foreland basin of the Ouachita orogeny formed by the oblique collision of the Laurentia and Gondwana continents during the late Paleozoic. Although current studies on the Fort Worth Basin focus mainly on unconventional hydrocarbon exploration and production, how the tectonic evolution of the basin has controlled the hydrocarbon maturation has not been well understood. Here we study the late Paleozoic evolution of sedimentation patterns in the Fort Worth Basin by correlating well logs and reconstructing isopach and structure maps. Our results show that the tectonic uplift of the Muenster Arch to the northeast of the basin and the Ouachita thrust belt to the east of the basin influenced the subsidence of the basin as early as the middle-late Mississippian, and caused the middle Mississippian-early middle Pennsylvanian strata thickening toward the two structures. The Ouachita thrust belt became the primary tectonic load of the basin by the late middle Pennsylvanian when the depocenter shifted to the east part of the basin. We then model the one-dimensional and two-dimensional subsidence histories of the Fort Worth Basin during the Paleozoic, and constrain its dynamic relationship to the basin-bounding Ouachita thrust belt. Because the latest Paleozoic-Cenozoic strata have been largely eroded in the region, which adds uncertainty to strata decompaction and subsidence reconstruction, we use Petromod 1D to conduct thermal maturation modeling in order to constrain the post-Paleozoic burial and exhumation histories by matching the modeled vitrinite reflectance with measured vitrinite reflectance along several depth profiles in the basin. Our thermal maturation modeling results show that the northeast part of the basin experienced a total of 6.5 km of subsidence during the Pennsylvanian and Permian, suggesting the flexural subsidence of the Fort Worth Basin continued to the Permian in response to the continued propagation of the Ouachita thrust belt. The propagation of the Ouachita thrust belt also caused subsidence acceleration of the basin during the middle Pennsylvanian-Permian, which then controlled hydrocarbon maturation of the Mississippian and Pennsylvanian sources rocks. This study advances our understanding to the tectonic control on hydrocarbon maturation in the Fort Worth Basin.

AAPG Datapages/Search and Discovery Article #90216 ©2015 AAPG Annual Convention and Exhibition, Denver, CO., May 31 - June 3, 2015