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Updated Overview of Structural Geology of Devonian Shales in Monroe, Noble, and Washington Counties, Ohio

Mark T. Baranoski

Detailed stratigraphic and structural mapping of Devonian shale units in Monroe, Noble, and Washington Counties has been performed by the Ohio Division of Geological Survey through a contract with the Gas Research Institute of Chicago, Illinois. This phase of a larger regional study used a computerized data base containing stratigraphic records from geophysical logs of approximately 3,000 wells.

Mapping on the lower Huron and "Gordon" units reaffirms the presence of the Cambridge arch and northern tip of the Burning Springs anticline, the two most prominent structures in this area. Several smaller anticlines have been mapped in the intervening area between the southeast-plunging nose of the Cambridge arch and the north-plunging nose of the Burning Springs anticline.

Subtle thickness increases of the lower Huron and Rhinestreet units correspond to structurally positive areas that occur along the trend of the Cambridge arch. The thickness increases are apparent on geophysical logs as locally expanded gamma-ray, neutron, and density curves. These anomalous areas may indicate the termination of upward imbrication near the edge of a decollement on the Silurian Salina E unit salt, as hypothesized by previous workers.

AAPG Search and Discovery Article #91031©1988 AAPG Eastern Section, Charleston, West Virginia, 13-16 September 1988.