Chapter 10 - Inverted fault systems and inversion tectonic settings

Abstract

Inversion structures are now recognized in most orogenic belts and in many other tectonic settings. Identification of inversion structures has been facilitated by classic geometric concepts that illustrated initial extensional fault geometry and its subsequent compressional reactivation as essential components of an inversion structure and by recent improvements in seismic imaging. However, many inversion structures in the outer parts of orogenic belts have been misinterpreted as either thin-skinned thrusts or strike-slip structures in outer fold-thrust belts and extensional basins, respectively. Furthermore, there remains some confusion about definition and usage of the term ‘inversion’, perhaps compounded by the fact that a wider range of geometric variations and associated deformation processes that meet the criteria for inversion are now recognized, compared to those illustrated in original discussions of several decades ago. This review focuses on: criteria for inversion structures, geometric signatures, different structural responses to inversion, tectonic settings for inversion and the time interval between extension and compression. A series of cross sections of inversion structures from a variety of tectonic settings are used to provide a reference catalogue of examples of inversion structures that cover the broad range of structural geometries that can be developed.