The Tectonic Development of the Rome Trough: A New Model and Its Exploration Implications
DRAHOVZAL, JAMES A.
Kentucky Geological Survey, University of Kentucky, Lexington, KY
TINA M WHITE
Department of Geological Sciences, University of Kentucky, Lexington, KY.
Preliminary seismic data interpretations for the Rome Trough of eastern Kentucky indicate that the tectonic history previously attributed to the feature has been only partially complete. Classically, the trough has been understood to be simply a syndepositional Cambrian extensional basin that was affected by later unspecified reactivation. Much of our understanding of this feature is based on well data. Only recently has seismic data been broadly available outside the oil industry. The Kentucky River Fault Zone on the north and the Rockcastle River Fault Zone on the south define the Cambrian syndepositional area. New interpretations of seismic profiles show that these fault zones are often characterized by major low-angle, north-vergent thrusting and associated folding that affect the section at least as high as the Knox Group. Above the Knox, data available to us do not sufficiently image the section. However, shallow structure-contour maps in the Carboniferous show folded areas south of and parallel to the thrust faults, indicating post-Pennsylvanian movement. Surface faulting in these areas, however, shows down-to-south normal faults.
Based on these observations, it appears that the tectonic development of the area consists of three major events: (1) Middle Cambrian synsedimentary extensional faulting, (2) Alleghanian contraction that developed thrust faults and anticlinal structures along original Cambrian extensional fault zones, and (3) relaxation or extensional post-Alleghanian normal faulting within these same fault zones, possibly related to the early Mesozoic break-up of Pangea. This new tectonic model has major implications for future petroleum exploration strategies in the area.