Date of Degree
PhD (Doctor of Philosophy)
Philip H. Heckel
Three named major cycles of marine transgression and regression (cyclothems) in the lower Cherokee Group are recognized from the Arkoma Basin margin in east-central Oklahoma across the northern Midcontinent shelf, on the basis of distinctive conodont morphotypes. The lowest of these (McCurtain) is characterized by Idiognathodus cf. praeobliquus and absence of I. obliquus and Idiognathoides. The middle cyclothem (Doneley) is the first major cyclothem to yield I. obliquus. The uppermost (Inola) yielded abundant Idiognathodus, Neognathodus and Idioprioniodus, and sparse Gondolella, and is characterized by large numbers of Idiognathodus podolskensis. All three contain large numbers of I. amplificus. At the base of the succession, the genus Idiognathoides in three cores from northeastern Kansas to south-central Iowa confirms the presence of Atokan strata in the Forest City Basin.
The McCurtain cyclothem extends from Oklahoma to the Forest City Basin in northeastern Kansas. The Doneley and Inola cyclothems extend from Oklahoma into Iowa. The Inola Limestone of Oklahoma is equivalent to the Hackberry Branch Limestone of western Missouri. The Bluejacket Coal of Oklahoma, at the base of the Inola cyclothem, is likely equivalent to Bluejacket A Coal of Kansas, Weir B or C coals in Missouri, and a middle Laddsdale coal in Iowa. The Rowe Coal of Oklahoma, Kansas, and Missouri, at the base of the Doneley cyclothem, is likely equivalent to the Cliffland Coal of Iowa. Inconsistent marine lithofacies in all three cyclothems suggest a complex depositional history on irregular surfaces.
Copyright 2010 Thomas Robert Marshall
Marshall, Thomas Robert. "Conodont-based correlation of major cyclothems in lower Cherokee group (Lower Desmoinesian, Middle Pennsylvanian), Oklahoma to Iowa." dissertation, University of Iowa, 2010.