Thrust Attributes and Potential Hydrocarbon Reservoirs in the Southern Appalachian Valley and Ridge

Robert D. Hatcher¹, Jennifer B. Whisner¹, and H. Virginia Weyland^2
1 University of Tennessee, Knoxville, TN
² U.S. Department of Energy, Tulsa,

Thrust fault populations in the southern Appalachian foreland fold-thrust belt reach a maximum of ten at the latitude of Knoxville, Tennessee, then decrease northeastward and southwestward. Displacements range from 10-15 km on smaller thrusts to 100 km on two master faults. Spacing between faults at present erosion level roughly equals the stratigraphic section thickness between the Lower Cambrian master décollement and the top of the Ordovician among smaller faults, and to the top of the Mississippian in large-displacement faults. Displacements of all thrusts sum to slightly less than the estimated minimum displacement on the Blue Ridge-Piedmont megathrust sheet (upper mechanical boundary) that pushed the thrust belt in front of it. Strong curvature of the Georgia-Tennessee-Virginia segment of the thrust belt that produced curved particle trajectories in thrust sheets may restrict plane strain to local across-strike 2–D segments of thrust sheets. Subthrust duplexes arch thrust sheets and create opportunities for footwall hydrocarbon accumulations. Two fields in southwestern Virginia and northeastern Tennessee produce within this setting, with production from the Ordovician upper Knox and Stones River (Black River) and Nashville (Trenton) Groups. Numerous untested prospects exist beneath the Saltville, Copper Creek, and other major thrusts in the central and western Valley and Ridge well within the oil-gas window. An additional largely unexplored 100-km long subthrust detachment fold-simple triangle zone (Eureka structure) exists in the Valley and Ridge.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005