Abstract: Exploration Strategies and Possible Submarine Fan Complexes in the Rough Creek Graben, Western Kentucky

James A. Drahovzal

The Rough Creek Graben is a deep, east-west-oriented rift basin more than 160 km long and 40 to 70 km wide in western Kentucky. It is a north-dipping half graben bounded on the north by the Rough Creek Fault Zone and on the east by a presumed tectonic inversion structure associated with reactivation of the East Continent Rift Basin. The half graben is filled with up to 5.5 km of dominantly marine sediments of the Cambrian pre-Knox Group that thin away from the Rough Creek Fault Zone.

Most of the pre-Knox oil and gas exploration in the graben has taken place near the Rough Creek Fault Zone. The boundary fault has a polyphase movement history and is characterized by extensive fracturing in and near the fault zone. Both the mechanical drilling problems and the lack of exploration success that have marked past exploration attempts are likely related to the high degree of fracturing associated with the northern edge of the graben. The pre-Knox rocks south of the boundary-fault zone are virtually untested and include viable exploration targets.

Recent investigations using limited seismic reflection data provide strong evidence for the presence of basin floor submarine fan deposition at least in the western, basal part of the graben. Several fan complexes up to 2 km in aggregate thickness have been interpreted in the northern part of the basin. To the south, thinner, less continuous fan deposits are inferred. If confirmed by drilling, these fan complexes could represent important future hydrocarbon reservoirs in many areas of the graben.

AAPG Search and Discovery Article #90954©1995 AAPG Eastern Section, Schenectady, New York