The Campania‐Lucania Extensional Fault System, southern Italy: A suggestion for a uniform model of active extension in the Italian Apennines

Abstract

By integrating new field data, seismic lines interpretation and a critical review of the literature, this work highlights a regional array of normal faults in the southern Apennines of Italy, which have been active during the Quaternary and are referred to as the “Campania‐Lucania Extensional Fault System” (CLEFS). The CLEFS consists of three main NW‐SE striking alignments of normal faults, which for the first time are considered genetically linked and methodically described in their geometry, kinematics and displacement. The CROP04 seismic profile, crossing the central part of the CLEFS, was strictly constrained by detailed geological surveys and reinterpreted to define the downdip trajectory of the major normal faults. These latter have been observed to splay from an east dipping low‐angle detachment surface penetrating the upper crust to depths of 12–13 km. The time‐space evolution of the faults and the associated basins was defined through a review of the stratigraphic data on the syntectonic deposits. As regards the overall geometry and the associate sense of shear (top‐to‐east), the CLEFS sensibly differs from the extensional features described previously in this region but shows surprising affinities with the “Etrurian Fault System,” an extensional megastructure of the northern Apennines. Remarkable similarities concern the extent, the surface and subsurface geometry, the timing of activity and the amount of the associated deformation. These common characters recognized over a belt nearly 600 km long lead to formulation of a low‐angle normal fault–driven extension geometrical‐kinematic model, which is sound for the whole active extensional belt of Italy.