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General southward thickening of pre-Desmoinesian stratigraphic units in eastern Oklahoma suggests the existence of a geosyncline on the south during the Paleozoic era until middle Pennsylvanian time.
The Arbuckle group thickens from 500 feet in northeastern Oklahoma to a postulated 5,000 feet in the McAlester basin. The overlying Simpson group is 700 feet thick in the basin, thins northward, and is absent north of Washington, Rogers, Mayes, and Delaware counties. The Viola-Fernvale limestone, Sylvan shale, and Hunton group in the McAlester basin have respective maximum thicknesses of 200, 70, and 255 feet. Northward truncation of Hunton and older units and overlap by the Chattanooga formation suggest strong post-Hunton southward tilting and warping. The Chattanooga averages 55 feet thick over most of the area and thickens toward the south. Post-Chattanooga Mississippian units are widespread in the area and vary locally from zero to 550 feet. The "Springer formation" occurs in a na row belt in the McAlester basin and is estimated to be 1,600 feet thick. The Morrowan series overlaps the "Springer" and attains a postulated thickness of 2,000 feet in the basin. Post-Morrowan uplift in the Ozark area and accompanying downwarp on the south are shown by a northward truncation of the Morrowan series. The overlapping Atoka formation thins from 6,500 feet in the McAlester basin to its northern limit in Tulsa, Rogers, Mayes, and Craig counties. Post-Atokan recurrence Of strong southward tilting is indicated by northward truncation of the Atokan and overlap by Desmoinesian beds.
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