Basal Detachment and Wrench Faulting
Horizontal displacements in transcurrent faults represent one of the fundamental modes of accommodation of deformation in the crust, crosscutting the entire lithosphere.
Studies of wrench faults eroded down to the middle to lower crust show that strain remains localized in transcurrent shear zones, and there is strong evidence that suggests a coherent deformation of the entire lithosphere in major intracontinental wrench faults.
The preservation of wrench fault fabrics within the upper mantle has major effects on the subsequent tectono-thermal behavior of continents, This anisotropy may explain the frequent reactivation, at continent scale, of ancient lithospheric-scale wrench faults and transpressional belts during subsequent tectonic events.
Higher tectono-thermal activity associated with wrench faults is linked to significant hydrocarbon source maturity and traps are associated with en echelon folds associated with such wrench faults.
Wrench faults have both compressional and extensional features and result from the orientations of their boundaries relative to regional plate motion.
Wrench faulting also commonly occurs in active margins or in collisional domains, but it is less clear whether intra-continental strike-slip fault systems generated in active margins or in collisional domains are only crustal structures or are rooted in the upper mantle. The penetration of a “wrench-fault type” tectonic fabric (i.e., a vertical flow plane associated with a horizontal flow direction) deep into the upper mantle may have major geodynamic implications,
A vertical zonation is common at structural levels above a basal detachment. Older basement structures commonly control development of younger structures.