Rome Trough Consortium: Structural/Tectonic Evolution of the Rome Trough Intraplate Extensional Graben System

Hickman, John B.¹, David C. Harris¹, and Mark T. Baranoski^2
1 Kentucky Geological Survey, Lexington, KY, and , 
² Ohio Division of Geological Survey, Columbus, OH

Results from a two year study by the Rome Trough Consortium, involving geologists from the state geological surveys of Kentucky, Ohio, and West Virginia, have recently been released. Unified regional interpretation of 761 wells allowed us to analyze stratigraphic and structural changes throughout this complex area with much greater accuracy than was available before.

The Rome Trough is a Cambrian extensional graben system (and possible aulacogen) that extends from northern Tennessee, northeastward through Kentucky, West Virginia, and into western Pennsylvania. It is a portion of the interior rift system that formed in conjunction with the opening of the Iapetus-Theic Ocean. The majority of extension within the Trough occurred during the Cambrian Period along high-angle, basement-rooted normal faults.

Contrary to most continental rifting models where the zone of normal faulting and crustal thinning expands in area over time, this study found evidence that a major portion of the Trough deformation narrowed though time. During the Middle Cambrian, the majority of fault movement causing the deepening of the Trough transferred from the Kentucky River fault zone in the north to the Irvine-Paint Creek fault zone farther south. A continuous section of the Rome Formation and Conasauga Group were formed through syn-tectonic sedimentation within the deepest portions of this rift valley. By the time the upper portions of the Nolichucky Shale (upper Conasauga Group) were deposited, the majority of the fault motion that created the Rome Trough had ended, however stratigraphic thickening over the Trough continued until at least the Middle Ordovician.

AAPG Search and Discovery Article #90031©2004 AAPG Eastern Section Meeting, Columbus, Ohio, October 3-5, 2004