Western Kentucky Precambrian Structure Map

Solis, M.P., Drahovzal, J.A., Greb, S.F., and Hickman, J.B.

Kentucky Geological Survey, University of Kentucky, Lexington, KY

New deep-well and reinterpreted seismic data were used to remap the Precambrian structure of western Kentucky, resulting in new interpretations for the structure of the Rough Creek Graben.  The graben is bounded by two east-west striking fault systems: to the north, the Rough Creek Fault System, and to the south, the Pennyrile Fault System.  The graben is disrupted by the Central Faults, a series of northeast-southwest-striking faults.  Fault motion along the Rough Creek faults is complex, but net motion is dominantly left-lateral strike-slip. 

A series of structural irregularities and discontinuities were found when elevations of the Precambrian surface were contoured from reinterpreted seismic lines.  Where these contouring irregularities coincided with trends of known surface faults, the faults were projected to basement to resolve the discontinuities.  This has resulted in the placement of several new faults to basement within the graben.  At least one of the faults crosses a seismic line and is substantiated by seismic data.  These northeast-trending faults formed a series of small basins on the Precambrian surface, which influenced overlying sedimentation.  Also, data from the Tarter well in Adair County extends the synclinal structure associated with the Rough Creek Graben eastward toward the Grenville Front, suggesting a possible connection with the Rome Trough in eastern Kentucky.  This well penetrates the top of Mount Simon Sandstone at a depth of -5,696 ft, but does not penetrate the base of the unit, indicating that basement is deeper than previously projected in this area.