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Major tectonic features of the central Mid-Continent area are outlined and their relationship to present thickness and distribution of pre-Desmoinesian strata is discussed.
Cambro-Ordovician "Arbuckle Group" thickens southward from zero along the Nemaha and Central Kansas uplifts to nearly 7,000 feet in southern Oklahoma. The Simpson, with maximum thickness of 3,000 feet in southern Oklahoma, thins northward by convergence and overlap of younger units to extinction in northwestern Kansas. Viola-Fernvale thins northward from 1,500 feet in Anadarko basin to 200 feet in southern Kansas, thickens to 400 feet in Salina basin.
The Sylvan-Maquoketa is limited to two areas, one in Oklahoma, the second in northeastern Kansas. Maximum thickness in Oklahoma is 600 feet, in Kansas about 150 feet. Distribution of Hunton resembles that of Sylvan; maximum thickness exceeds 1,500 feet in Oklahoma and 650 feet in Forest City basin. Woodford-Chattanooga lies with regional unconformity on units from Precambrian through Hunton. A 600-foot maximum is postulated for the Anadarko basin; 50-100 feet covers eastern Oklahoma and Kansas. Mississippian limestones are widespread with 4,000 feet in Anadarko basin, 1,600 feet in Hugoton embayment and zero in northern Kansas.
Lower Pennsylvania Springer is limited to a narrow belt in Anadarko and McAlester basins with maximum of 4,000 feet near Ardmore. Overlying Morrow overlaps Springer reaching maximum of 1,500 feet in McAlester basin and more than 4,300 feet in Anadarko basin. Distribution of Atoka resembles that of Morrow with 5,000 feet maximum in the Anadarko basin and approximately 8,000 feet in the McAlester basin. Widespread Desmoinesian sediments rest with marked unconformity on Atokan and older rocks.
Epeirogenic movements were mild throughout early Paleozoic with geosynclinal development in southern Oklahoma. Eustatic changes produced major unconformities and offlap-overlap relations. Strong warping occurred in post-Hunton, pre-Chattanooga time. Major orogenic movements are post-Mississippian, pre-Desmoinesian with maximum movement in late Morrowan. Final structural development took place in late Cretaceous and early Tertiary. Throughout much of Paleozoic time, the axis of maximum deposition in southern Oklahoma paralleled the Wichita-Amarillo trend in the "Wichita embayment."
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