Fault inversion: An example in central Apennines (Italy)

Abstract

Phenomena related to large scale fault inversion have been observed on the basis of geological and structural evidence in the Central Apennines, along the northern extension of southwestern margin of Mi Velino, 20 km east from L'Aquila (Central Italy)Two main tectonic events have been recognized by macro and mesostructural analyses. The compressional tectonic phase developed in Late Miocene-Early Pliocene produced thrusting of carbonate units onto Late Miocene-Messinian ones. Related to this tectonic event, high and low angle reverse faults have been identified, linked to a NW-SE and N-S trending thrust systems. During the following extensional phase, NW-SE trending faults began to be active and high angle NW-SE striking reverse faults were reactivated as normal faults with a very small left-lateral component. This last tectonic event probably developed during Early-Middle Pleistocene as was hypothesised in neighbouring areas. Between these two events, transpressional tectonics produced NW-SE left lateral faults which displaced the pre-formed thrust faults. Great portions of the ancient thrust planes are now exposed consequent to the final extensional movement that generated "fault slope features".