Polyphase Tectonic Movement: Southern Edge of the Rome Trough

T. M. White¹ and J. A. Drahovzal^2
1Department of Geological Sciences, University of Kentucky, Lexington, KY
²Kentucky Geological Survey, University of Kentucky, Lexington, KY

The Rome Trough is a Middle Cambrian, asymmetric, rift graben that can be traced from eastern Kentucky throughWest Virginia and into Pennsylvania. In Kentucky the trough is bounded on the northwest by the Kentucky River Fault System, on the west by the Lexington Fault System, and on the southeast by the Rockcastle River Fault System. The Rockcastle River, Pike County, and Perry County Uplifts lie south of the Rockcastle River Fault.

The presence of these uplifts has been indicated by gravity anomalies and limited well data. An examination of single-fold, reflectionseismic data verifies the existence of the Rockcastle River Uplift and reveals a marked divergence of dip within the Cambrian reflectors on the northern side of the Rockcastle Fault. Deeper reflectors dip steeply south into the fault, whereas shallower reflectors dip to the north away from the fault. Post-Cambrian reflectors at the northern edge of the fault also show a pronounced north dip. The reflector patterns suggest Middle Cambrian extension across an originally north-dipping, listric growth fault. Later, tectonic shortening apparently rotated the fault to a south-dipping orientation and uplifted the southern block to form the Rockcastle River Uplift, dragging up the Middle Cambrian-Middle Ordovician beds on the northern block.

Determining the timing of this uplift and its relationship to the other structures along the southern edge of the Rome Trough will require further work and additional seismic data.

AAPG Search and Discovery Article #90900©2001 AAPG Eastern Section Meeting, Kalamazoo, Michigan