REVISED STRATIGRAPHIC RELATIONS IN THE UPPER ORDOVICIAN (KATIAN; UPPER MAYSVILLIAN-RICHMONDIAN) OF CENTRAL AND NORTHERN KENTUCKY: HIGH RESOLUTION CORRELATION, REGIONAL FACIES EVOLUTION, AND MODIFIED NOMENCLATURE

Upper Ordovician (Katian) strata are well exposed in Kentucky, and permit recognition of a lithologic and faunal gradient spanning shallow, peritidal facies in the southeast to mid-ramp, subtidal facies in the northwest. Unfortunately, refined understanding of stratigraphic relationships within the upper Maysvillian-lower Richmondian succession is complicated by 1) an abundance of local or facies-specific lithostratigraphic terms, 2) significant lateral changes in lithofacies corresponding to the regional gradient, and 3) differential erosion of strata beneath a large number of variably significant unconformities. Detailed examination of numerous exposures concentrated near Owingsville, central Kentucky and Maysville, northern Kentucky permit construction of composite sections to allow high-resolution comparison and correlation of these strata. This study uses the identification of key stratigraphic surfaces along the regional facies gradient to track the lithological changes within these units. Tracing these surfaces from subtidal to peritidal, along with documenting the facies changes, will allow for correlation of units independent of lithostratigraphic terms, and demonstrate the importance of the unconformities which bound them, some of which have been previously overlooked. Moreover, this method leads to a uniformed set of names, consistent throughout the region which in turn will lead to more accurate correlations in future work.