REVISED UPPER PENNSYLVANIAN STRATIGRAPHY OF ILLINOIS BASIN WITH REGIONAL CORRELATIONS

This poster illustrates our revised stratigraphy for the Upper Pennsylvanian (Missourian and Virgilian series) of the Illinois Basin. For each unit, we reconsidered the type section and tied it into the subsurface, using core data when available. A network of cross sections was then constructed, maximizing use of newly acquired long core records. Through this process, many redundant unit names have been eliminated. Precise biostratigraphic correlations from palynology, fusulinids, and especially conodonts from Phil Heckel and other workers, allowed extending a number of members, particularly black, phosphatic shales, from the Western Interior into the Illinois Basin and Appalachian Basin. The poster includes charts correlating many units among Appalachian, Western Interior and Illinois Basin regions. Many long-standing miscorrelations within the Illinois Basin have been rectified. This work represents the first official revision of Illinois Basin Upper Pennsylvanian stratigraphy in 20 years.