Abstract: Structural Genesis of Northwestern Ohio — A Seismic Reconnaissance

T. JOSHUA STARK
Horizontal Ventures, Inc., Tulsa, OK
and LAWRENCE H. WICKSTROM
Ohio Division of Geological Survey, Columbus, OH

Equitable Resources, Inc., and Seneca Resources, Inc., recently completed a large exploration program in northwestern Ohio that included an extensive array of new reflection seismic data. These new seismic data, together with potential fields and historic well data indicate much of the structural geology of the area is linked to remobilization of deep Proterozoic elements. Rifting, probably of Keweenawan age, localized low-density sediments and volcanics in the East Continent Rift Basin. The subsequent Grenville collision thrust metamorphic allochthonous blocks above, and adjacent to, the rift assemblage. These Precambrian events and their resultant structural fabric defined the zones of weakness reactivated by later Paleozoic tectonic forces.

Extensional and growth faults evolved from Cambrian - Ordovician passive-margin tectonics, effecting syndepositional facies and thickness changes. The Taconic Orogeny had the greatest impact on Paleozoic strata in this region. Uplift, probably associated with lithospheric flexure influenced by underlying Precambrian geology, gave rise to the Ohio-Indiana Platform and the Findlay Arch. Compressional forces caused complex, anastomosing wrench systems following Precambrian block boundaries and along the Grenville suture itself. Later, Alleghenian adjustments to these structures were minor but may have breached the integrity of some prospective reservoirs.

AAPG Search and Discovery Article #90930©1998 AAPG Eastern Section, Columbus, Ohio