Updated Lithostratigraphy and Nomenclature for Ohio’s Sub-Knox Cambrian Strata

Baranoski, Mark T.¹, David C. Harris², and John B. Hickman^2
1 Ohio Division Of Geological Survey, Columbus, OH
² Kentucky Geological Survey, University of Kentucky, Lexington, KY

A network of nine regional cross sections across Ohio and the surrounding region using wire-line log suites illustrates updated Sub-Knox Cambrian lithostratigraphy and provides a basis for revision of associated current stratigraphic nomenclature. Stratigraphic units affected by preliminary mapping of the updated lithostratigraphy are the currently used terms: Mount Simon Sandstone, Eau Claire Formation, Conasauga Formation, and Rome Formation. The term Rome Formation is dropped from Ohio nomenclature, as existing data show that the unit is confined to the structural Rome Trough southeast of Ohio. The term Conasauga Formation is expanded to Conasauga Group, which also includes mappable units previously termed Rome Formation and Mount Simon Sandstone.

The Mount Simon is not a regional Cambrian “blanket sandstone” as traditionally mapped, and is limited to western Ohio and adjacent areas of Michigan, Indiana, and Kentucky. Following deposition of the Mount Simon, the Eau Claire Formation of western Ohio merged across the Ohio region with the Conasauga Group of eastern Ohio forming a regional platform dominated by cyclic mixed clastic-carbonate sediments throughout central Ohio and carbonates in eastern Ohio. The lower portion of the Conasauga Group of extreme eastern Ohio may contain stratigraphically time equivalent facies to the Mount Simon of western Ohio, but cannot be unequivocally proven in the absence of paleontologic and isotopic data. This new work has implications for crustal and tectonic studies, basin analyses, and reservoir studies for hydrocarbon exploration, industrial waste disposal, gas storage, and CO₂ sequestration.

AAPG Search and Discovery Article #90031©2004 AAPG Eastern Section Meeting, Columbus, Ohio, October 3-5, 2004