Midcontinent Pennsylvanian conodont zonation

摘要

We update the Midcontinent North American conodont zonation of Barrick and others (2004), which provides a means for correlating Pennsylvanian strata around the Midcontinent Basin and with contemporaneous strata elsewhere in North America. Species of Neognathodus dominate the zonation for Early and Middle Pennsylvanian strata. Morrowan through Desmoinesian Neognathodus zones comprise, in ascending order: N. higginsi, N. symmetricus, N. bassleri, N. nataliae, N. atokaensis, N. colombiensis, N. caudatus, N. asymmetricus, and N. roundyi. Species of Idiognathodus and the related genera Swadelina and Streptognathodus provide the zonation for late Middle (Desmoinesian) and Late Pennsylvanian strata. Idiognathodid-based zones for the Desmoinesian through Virgilian stages comprise, in ascending order: Idiognathodus amplificus/ obliquus, I. rectus/I. iowaensis, I. delicatus, Swadelina neoshoensis, Sw. nodocarinata, I. eccentricus, I. turbatus, I. cancellosus, I. confragus, Streptognathodus gracilis, I. eudoraensis, S. zethus, I. simulator, S. vitali, S. virgilicus, S. bellus, S.flexuosus, S.farmeri, and S. binodosus. The Desmoinesian through Virgilian stages contain widespread eustatic cyclothems, many of which are characterized by unique combinations of taxa that may eventually allow refined 'digital' correlation on a continental to ultimately global scale.