ABSTRACT

Varied structural styles consisting of compressional and extensional features suggest that the Reagan Fault represents a wrench fault zone activated sometime in Early Pennsylvanian. The various structural and stratigraphic observations along the Reagan Fault in the study area include: en echelon folds and thrusts at a 10 to 15° clockwise angle to the fault, synthetic faults at a 10 to 30° counterclockwise angle and antithetic faults at a 80 to 90° counterclockwise angle to the fault, fracture sets with low plunging slickensides in the direction of the fracture trend, extreme brecciation and spaced cleavage development in the fault zone, Precambrian granitic basement involvement during deformation, 10,000 ft. (3 km) of vertical uplift concurrent with horizontal movement, and major lithologic and thickness differences in the Hunton Group across the fault. These features fit within a wrench fault model proposed by Wilcox, Harding and Seely (1973). Pennsylvanian left slip on the order of 10 to 15 mi. (16 to 24 km) may have occurred along the Reagan Fault.