GLOBAL CATALOGUE, CLASSIFICATION AND TECTONIC ORIGINS OF RESTRAINING- AND RELEASING BENDS ON ACTIVE AND ANCIENT STRIKE-SLIP FAULT SYSTEMS

Abstract

Restraining- and releasing bends with similar morphology and structure have been described by many previous studies of strike-slip faults in a variety of active and ancient tectonic settings. Despite the documentation of at least 49 restraining and 144 releasing bends along active and ancient strike-slip faults in the continents and oceans, there is no consensus on how these structural features are named and classified, or how their wide range of structures and morphologies are controlled by the distinctive strike-slip tectonic settings in which they form. In this overview, I have compiled published information on the strike-slip tectonic setting, size, basin and bend type, age, and models for active and ancient releasing and restraining bends. Examples of bends on strike-slip faults are compiled and illustrated from five distinctive active strike-slip settings: oceanic transforms separating oceanic crust and offsetting mid-oceanic spreading ridges; long and linear plate-boundary strike-slip fault systems separating two continental plates whose plate-boundary kinematics can be quantified for long distances along strike by a single pole of rotation (e.g. the San Andreas fault system of western North America); relatively shorter, more arcuate indent-linked strike-slip fault systems bounding escaping continental fragments in zones of continent–continent or arc–continent collision (e.g. the Anatolian plate); straight to arcuate trench-linked strike-slip fault systems bounding elongate fore-arc slivers generated in active and ancient fore-arc settings by oblique subduction (e.g. Sumatra); and cratonic strike-slip fault systems removed from active plate boundaries, formed on older crustal faults, but acting as ‘concentrators’ of intraplate stresses.