LOWER MISSISSIPPIAN STRATIGRAPHY OF THE APPALACHIAN BASIN: UNRESOLVED LITHOSTRATIGRAPHIC AND BIOSTRATIGRAPHIC PROBLEMS

Changes in nomenclature across state lines, as well as facies changes, have complicated Lower Mississippian stratigraphy in the Appalachians. The stratigraphic relationships between the Cuyahoga and Logan formations of Ohio and the Borden Formation of Kentucky are unclear. The Borden in Kentucky is predominantly Osagean based on conodonts and miospores. In Ohio, the Cuyahoga and Logan formations are presumed to be predominantly Kinderhookian based on ammonoids, brachiopods, miospores, and a single bed of conodonts. Better understanding of the lithostratigraphic relationships between these formations may resolve apparent discrepancies in the biostratigraphic data. A clear lithostratigraphic framework would also assist in the interpretation of the Black Hand Sandstone of the Cuyahoga Formation. This unit has been interpreted as a coarse-grained deltaic deposit in gradational contact with the Cuyahoga. However, the Black Hand does not appear to be a deltaic sandstone. It contains large trough cross beds, mega shale rip-up clasts, and coarse to conglomerate-size grains, indicative of deposition in a fluvial setting, possibly a braided stream. Shale clasts in the Black Hand suggest that the contact between the Black Hand and the Cuyahoga may have been incised. The juxtaposition of fluvial and marine sediments is a primary criterion for identifying incised valleys. Recognition of this situation requires the integration of several different types of data: outcrop, subsurface, lithostratigraphic and biostratigraphic. Incorporation of all available data into a new stratigraphic model based upon sequence stratigraphic principles may resolve some of the litho- and biostratigraphic discrepancies in the Lower Mississippian.