Wrench Faulting in Selected Areas of Permian Basin

ABSTRACT Landsat and NASA High Altitude Special Mission Aircraft imagery have made it possible to define at least six separate lineament trends between the Amarillo-Wichita uplift (N62°W) and the Texas lineament (N54°W) that are 200 to 330 mi (320 to 530 km) long and oriented N54°W to N62°W. These long lineaments are thought to be P shears and are left-lateral wrench faults by definition. Wrench faults, transcurrent faults, and strike-slip faults are basically synonymous; all are shear faults. Wrench faults in the earth’s crust are characterized by the following: (1) very long, straight traces; (2) high angle of dip (fault with over 70° dip should be examined closely); (3) en echelon nature of faulting; (4) angles between faults that suggest shear patterns; (5) earthquake history in the region; and (6) offsets. This left-lateral wrench fault system has been demonstrated at the Carta Valley fault zone. The Permian surface between Brown-Bassett and JM field of Terrell, Crockett, and Val Verde Counties along the Pecos River has a fracture system that is compatible with wrench faulting. In Garza and Borden Counties, the elements of left-lateral wrench faulting can be demonstrated from high altitude aircraft imagery and demonstrated on the surface and in the subsurface with seismic support. Surface lineaments are observed on Landsat imagery throughout the Permian basin and lead to the belief that the very long N54° to 62°W lineaments are P shears. The set oriented N86° ± E are the Riedel shears and the N36°E are conjugate Riedel shears. These form high angle en echelon faults of a left-lateral wrench fault system that can be documented with faulting at the surface in Borden and Garza Counties, and with the surface alignments being documented on CDP seismic lines in the subsurface.