Structural and Stratigraphic History of Late Paleozoic and Early Mesozoic of Northwestern Gulf of Mexico

Jeffrey V. Milliken

Late Paleozoic and early Mesozoic sedimentation in southern Arkansas, northern Louisiana, and northeastern Texas reflects a sequential change from compressional tectonism to extensional tectonism. Seismic, well, and surface data allow resolution of five tectonostratigraphic events between Early Pennsylvanian and Early Jurassic: (1) Ouachita Thrusting--A balanced cross section extending from southeastern Oklahoma to northeastern Texas indicates that north-directed thrusting during the Atokan involved a southward-thickening early Paleozoic passive-margin sedimentary wedge, Precambrian basement, and northward-thickening syntectonic foredeep sediments. Initial shortening of the passive-margin wedge along the Ti Valley fault was followed by basement-involved duplexing beneath he Ti Valley thrust sheet. (2) Post-Atokan Unconformity--Uplift and erosion created a regional angular unconformity during earliest Desmoinesian time. (3) Southern Ouachita Successor Basin--Extension, basin subsidence, and sedimentation started in the southern part of the Ouachita orogen during the early Desmoinesian. Shallow-water carbonate and marginal marine clastic deposition continued through the remainder of the Paleozoic. (4) Triassic Rifting--A second period of extensional faulting during the Triassic created a series of mostly east-west-trending basins. Seismic stratal patterns indicate that these basins were filled by axial progradation of fluvio-deltaic systems. (5) Regional Subsidence--The Jurassic was dominated by regional subsidence. Deposition of Werner sands and anhydrite in remnant topographic lows was followed by widespread deposition of the Louann Salt. Of these five events, the first three are considered part of the Ouachita orogeny, whereas the last two are related to opening of the Gulf of Mexico.

AAPG Search and Discovery Article #91030©1988 AAPG Annual Convention, Houston, Texas, 20-23 March 1988.