
Structural evolution of the Killbuck Dome, east-central Ohio
WICKS, JOHN L., Red Bird Producing Company, Wooster, OH; and WICKSTROM, LAWRENCE H., Ohio Division of Geological Survey, Columbus, OH
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.