LATE PALEOZOIC TECTONO-STRATIGRAPHY OF THE MID-CONTINENT: INSIGHTS FROM SUBSIDENCE ANALYSIS

The Pennsylvanian-Permian basins of Oklahoma, North Texas, and environs represent a complex mosaic of Ouachita forelands and Ancestral Rocky Mountain (ARM) basins and uplifts. As part of a larger analysis of late Paleozoic Laurentia, we have built 85 basin and 26 flexural models to better understand the relative timing and potential kinematic linkage of the various elements. A particular challenge is the reconstruction of upper Pennsylvanian and Permian strata, which are oft not preserved in the forelands because of exhumation. The missing section is estimated from basin models, calibrated to observed vitrinite reflectance and borehole temperatures. The onset of flexural subsidence for the greater Ouachita system becomes younger from east (Black Warrior Basin) to west (Val Verde), indicating a possible “zippering” of the collision with Gondwana. Rapid subsidence begins in the Arkoma in the late Morrow (ca. 321 ma), with a possible forebulge and associated unconformity identified in NE Oklahoma. Reconstruction of eroded late Paleozoic section indicates up to 1.2 km of upper Desmoinesian through Permian strata was deposited in the Arkoma basin. The Anadarko and Hardeman basins had the oldest onset (ca. 335 Ma) of rapid subsidence of the 12 ARM basins evaluated – possible evidence of the early uplift of Wichita Mountains. This may be a result of the profound weakness (and subsequent inversion) of the South Oklahoma Aulacogen. Flexural models of the Ouachita forelands and the Anadarko Basin indicate that the basin fill geometry is consistent with a flexural origin. Estimates of flexural rigidity from these models are also broadly in line with current estimates of crustal strength from seismic tomography.