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ABSTRACT: Lower Paleozoic and Shallow Proterozoic Structural Geology of Western Ohio as Interpreted from the Reprocessed Cocorp Seismic Profile

WICKSTROM, LAWRENCE H., Ohio Geological Survey, Columbus, OH, JAMES A. DRAHOVZAL, Kentucky Geological Survey, Lexington, KY, and PHILIP E. TOWEY, Philip Towey and Associates, Pittsburgh, PA

In 1987, the Consortium for Continental Reflection Profiling (COCORP) conducted a west-to-east seismic traverse across Ohio to investigate deep crustal geology. Data from the western portion of this transverse (COCORP OH-1) was recently reprocessed to reveal details of the Paleozoic and Proterozoic section which were indistinct on earlier versions.

From the Ohio-Indiana border eastward for approximately 60 mi, the Paleozoic strata are underlain by a package of weak, discontinuous reflectors interlayered with strong, continuous reflectors. We interpret this package to represent an interlayered series of Proterozoic sedimentary and basaltic units. This series ranges in thickness from a few hundred feet to over 11,000 ft.

East of Logan County, Ohio, characteristic east-dipping reflectors of the Grenville Province lie below the Paleozoic section. The transition between the Proterozoic sedimentary sequence to the west and the Grenville rocks to the east is interpreted to be a complex fault system having several episodes of movement.

The position of the Fort Wayne rift of the East Continent Gravity High coincides with a portion of the profile which displays uplifted Proterozoic reflectors. The COCORP line also crosses the Bellefontaine outlier; an anomalous body of Devonian rocks surrounded by Silurian rocks. We interpret this outlier, which includes the highest elevation in the state and was once thought to be simply an erosional phenomenon, as having deep structural roots. The thickest portion of the Proterozoic sedimentary sequence lies beneath the outlier, and several faults which pass through the Proterozoic section also propagate into the overlying Paleozoic section.

 

AAPG Search and Discovery Article #91013©1992 AAPG Eastern Section Meeting, Champaign, Illinois, September 20-22, 1992 (2009)