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Abstract: Structural Evolution of the Killbuck Dome, East-Central Ohio

WICKS, JOHN L. and LAWRENCE H. WICKSTROM

Interpretation of seismic and well data in southern Holmes and northern Coshocton Counties, Ohio indicates a complicated structural history in which compressional and extensional tectonism alternated over geologic time. A domal uplift, the Killbuck Dome, is cut by a series of deep faults and northeast-trending anticlines. Four episodes of tectonic activity are recognized on the structure: 1) Precambrian thrusting, 2) Upper Cambrian extensional faulting, 3) Upper Cambrian and Lower Ordovician Knox-age uplift and 4) Upper Ordovician-Lower Silurian thrusting. Minor additional uplift occurred after the Mississippian Berea Sandstone was deposited.

Deep faults transect the dome predominantly in the Precambrian through Rome section, and are thought to have originated as Grenvillian thrust faults. The faults were reactivated during Cambrian time, when they served as normal faults accommodating regional extension. Most of Rome depositional time is interpreted as passive fill of the extensional basin. An episode of uplift is seen following Copper Ridge deposition, and may have persisted through Knox unconformity time. The Cambrian-age extensional features were inverted during Cincinnatian time. Finally, structure contours on the top of the Berea Sandstone suggest some movement occurred after Berea deposition.

Unraveling the timing of these structural events has proven critical to successful exploration for Knox unconformity traps in this area. Many dry holes have been drilled on late structures, which were mistaken for Knox erosional remnants.

AAPG Search and Discovery Article #90939©1997 AAPG Eastern Section and TSOP, Lexington, Kentucky