Southern Midcontinent region
Kenneth S. Johnson, Thomas W. Amsden, Rodger E. Denison, Shirley P. Dutton, Arthur G. Goldstein, Bailey Rascoe, Jr., Patrick K. Sutherland, Diana Morton Thompson, 1988. "Southern Midcontinent region", Sedimentary Cover—North American Craton, L. L. Sloss
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The Southern Midcontinent is a complex region characterized by great thicknesses of sediments preserved in a series of major depositional and structural basins separated by orogenic uplifts created mainly during Pennsylvanian time (Plate 5-A).Sedimentary rocks of every geologic system from Precambrian through the Quaternary are preserved within the region, and their diverse lithologies include limestones, dolomites, sandstones, shales, conglomerates, red beds, and evaporites. The strata are a mixture of marine and nonmarine deposits, and generally (except for the red bed-evaporite sequences), they are richly fossiliferous and are well suited to biostratigraphic correlation and interpretation of depositional environments.
Dominant lithologies in most basins of the region are, in ascending order, as follows: a thin transgressive sandstone of Late Cambrian age that covered the basement-rock complex of intrusives, extrusives, and metasediments; overlain by a thick sequence of Late Cambrian through Late Mississippian (Meramecian) carbonates, with minor amounts of sandstone and shale; followed by a thick sequence of terrigenous clastics, with some carbonates, deposited from Late Mississippian (Chesterian) through Early Permian (Wolfcampian) time; then a thick series of red beds and evaporites were deposited during the remainder of the Permian; overlain, in the west only, by Triassic and Jurassic terrestrial red beds; then Cretaceous marine deposits in the south and west; and finally a mantle of Tertiary alluvial-fan, aeolian, and lacustrine sediments in the west. Owing to the great thickness of strata in most basins of the region, and the many surface and subsurface stratigraphie studies that have been conducted, a plethora of
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Sedimentary Cover—North American Craton
The “sedimentary cover” refers to the stratified rocks of youngest Proterozoic and Phanerozoic age that rest upon the largely crystalline basement rocks of the continental interior. The early chapters of the volume present data and interpretations of the geophysics of the craton and summarize, with sequential maps, the tectonic evolution of the craton. The main body of the text and accompanying plates and figures present the stratigraphy, structural history, and economic geology of specific sedimentary basins (e.g., Appalachian basin) and regions (e.g., Rocky Mountains). The volume concludes with a summary chapter in which the currently popular theories of cratonal tectonics are discussed and the unresolved questions are identified.