Brief geological setting
In the central Mediterranean region, the Apenninic-Maghrebian orogen is the result of the convergence between Eurasia and Africa that has been leading since Late Cretaceous to the juxtaposition of arcuate fold-and-thrust belts and associated back arc basins (Dewey et al., 1989).
The Apennines and Sicily are the result of the development of a convergent orogenic wedge above subduction of the remnant of the Neotethys Ocean followed by collision with the continental passive margins of the Adriatic microplate and Africa plate and the opening of the Tyrrhenian Sea back-arc basin (Dewey et al., 1989; Malinverno and Ryan, 1986; Boccaletti et al., 1990; Faccenna et al., 2004).
Since the Late Cretaceous to Middle Eocene, consistent portions of the Mesozoic oceanic lithosphere were subducted. The chain developed through the deformation of major paleogeographic internal domains (tectono-sedimentary sequences of the Ligurian-Piedmont Ocean) and external domains (sedimentary sequences derived from the deformation of the continental Adria-African passive margin). The continuity of the Apennine chain is abruptly interrupted in the Calabrian Arc by the Kabylo-Calabrian crystalline terranes. Major complexities (e.g., sharp deflections in the arcuate thrust belt configuration, thrusts out-of-sequence propagation) are referred to contrasting rheology and differential buoyancy of the subducted lithosphere and consequent differential rollback of the Adria plate margin, and to competence contrasts in the Mesozoic stratigraphic sequences, where multiple décollement horizons at different stratigraphic levels may have favoured significant differential shortening.
Since the Late Miocene, thrust belt geometry was strongly modified by extensional faulting, volcanic activity, crustal thinning and formation of oceanic crust related to the development of the Tyrrhenian Basin (Elter et al., 2003).