EARLY TO MIDDLE PALEOZOIC TECTONIC EVOLUTION OF THE EASTERN U.S. MIDCONTINENT

New data collection from Paleozoic strata across the U.S. Midcontinent obtained through critical minerals and carbon sequestration studies enable fine-tuning of paleogeographic and tectonic interpretations. Refining regional tectonic histories and basin geometries is essential to advancing critical minerals exploration models and characterizing zones of structural weakness essential to responsible carbon sequestration efforts.

Integration of new bio-chemostratigraphic, facies, and geochronologic data from across broad portions of the eastern Midcontinent are the basis for a robust sequence stratigraphic framework that unravels the complex geologic history of this region. Recently published geochronologic studies provide precise timing for formation of the Mississippi and Oklahoma aulacogens during the early Cambrian phase of Rodinian rifting. This extensional tectonic regime resulted regionally in broad facies belts flanking the aulocogens, revealing the subtle paleobathymetric trends of a single large Midcontinent basin. Despite pulses of mountain building on the southern Laurentian margin during the Upper Ordovician, Silurian, and Lower Devonian, the orientation of Midcontinent facies belts remained little changed. However, late Middle Devonian strata onlap subtle angular unconformities in several areas across the eastern Midcontinent indicating basement block uplifts with vertical displacement of up to several hundred meters.

Our ongoing studies confirm models showing a broad early Paleozoic Midcontinent basin stretching from the Transcontinental Arch to the Cincinnati Arch. Evidence from a variety of data types suggests that portions of this basin became dramatically inverted during the late Middle Devonian indicating the onset of far-field compressional tectonics and the first Paleozoic uplift of portions of the ancestral Ozark Dome coincident with the Third Tectophase of the Acadian Orogeny.