Backthrusting, nappe refolding, and normal faulting frequently characterize late collisional stage of an orogen.Shortening driven by backthrusting is widely reported in the Alpine orogen, and it has been proposed to beresponsible for the increase of subsidence (Roure et al., 1990). Moreover delamination and backthrusting has beenconsidered as related to subcritical condition of a Coulomb-type accretional wedge (Torres Carbonell et al., 2011).The Sicilian Fold and Thrust Belt (SFTB) was characterized by a three-stage evolution during the last 15 My: twomain shortening events generated and developed at different structural levels (shallow- and deep-seated thrusts inthin-skinned thrust-model) and at different time intervals, involving mainly the Meso-Cenozoic carbonate units ofthe ancient African passive continental margin, followed by a more recent thick-skinned thrust-model involvingthe Plio-Pleistiocene deposits in the frontal area as well as the crystalline basement in the internal sector of thechain.We investigated the northern Sicily continental margin by using differently-penetrative seismic reflection data,calibrated with field surveys and borehole data. The tectonic edifice appears to be interested, both offshore andonshore, by a structural style typical of a triangle zone bounded, on the southern side by N-dipping high-angletranspressional faults, mainly Early Pliocene to Early Pleistocene in age, and on its northern side, by high-angleS-dipping thrusts, deeply connected with a low-angle décollement layer. In the outer sector of the SFTB,double-verging structures (with NW and SE-tectonic transport) have been described for the Plio-Pleistoceneevolution of the Gela Thrust System. The southern Tyrrhenian region is also interested by normal faulting andsubsidence, delamination processes, and widespread deep seismicity.A late Miocene-Quaternary northern migration of the plate margin producing opposite-verging structures isreported in the northern Africa plate boundary (e.g. NW Algeria Neogene margin; Yelles et al., 2009; Mauffret,2007). A plate boundary reorganization during the latest 0.8–0.5 My with the development of backthrusts havebeen documented in the Mediterranean region (Goes et al., 2004).Our hypothesis is that the most recent tectonic processes in the study region are representative of a late collisionalstage in the northern Sicily mountain building and at a larger scale could be a precursor of a change in thesubduction polarity in the central belt of Mediterranean, as a consequence of the ongoing collision of the Africanpromontory with the thinned continental to oceanic sectors (Algerian and Tyrrhenian basins) of the European plate.
|Numero di pagine||1|
|Stato di pubblicazione||Published - 2018|