ABSTRACT: Pre-Mount Simon Tectonic Basins in Western Ohio

Ernest C. Hauser, Benjamin H. Richard, Stephanie Nowak, and Paul J. Wolfe, Wright State University, Dayton, OH

Two subparallel Pre-Mount Simon basins have been identified in southwestern Ohio on seismic sections. These basins contain sediments that are thousands of feet thick and each basin is about ten miles (14 km) wide. They trend roughly north-south and appear to sit adjacent to (astride?) the Grenville Front Tectonic Zone. These basins appear as structural basins locally preserving what were once more regionally extensive Pre-Mount Simon sedimentary strata. Faulting is locally extensive in the Precambrian units beneath, but the strata in the overlying basins are less or little faulted. A drill hole into the upper part of the western Warren-Clinton County Basin encountered only lithic arenite (the Middle Run Formation); however, in the eastern basin (Selma Basin) a drill hole encountered limestone below the Mount Simon.

The relationship of the stratigraphy within these adjacent basins is not yet fully understood, however, two possibilities can be posed. One is that the limestone of the Selma Basin overlies a seismically transparent correlative of the Middle Run lithic arenite and that both are a remnant of a much more extensive unit (similar pre-Mount Simon limestone is known to exist in deep wells in eastern Indiana). Another possibility is that the limestone of the Selma Basin is older and correlates with the distinctly strong reflective layering beneath the Middle Run of the Warren-Clinton County Basin and is more extensive throughout the Granite Rhyolite Province to the west (i.e., in eastern Indiana). The latter also addresses the problem of a lack of any significant potential field anomaly where these layered rocks subcrop beneath the Mount Simon in Warren County (as one might expect if they instead represent mafic flows or intrusions).

Search and Discovery Article #90907©2000 AAPG Eastern Section Meeting, London, Ontario, Canada