Ricostruzione paleogeografica e geodinamica della Sicilia sulla base dei dati geologici e geofisici

The Apenninic-Maghrebian thrust belt-foredeep system is composed of the inner margin of the Foreland Domain and of the Orogenic Domains. The Foreland Domain includes the still undeformed continental areas of Africa, represented by the Pelagian Block and to the north those of the Adria Plate, consisting of the Apulian Block, separated since the Permo-Trias by the oceanic crust of the Ionian Basin. The Orogenic Domains are composed, from the external to the internal areas of three main chains: the External Thrust System(ETS), the Apenninic-Maghrebian Chain (AMC), and the Kabilo-Calabride Chain (KCC). The first one originated since Tortonian time by the detachment of the most internal sedimentary covers of the flexured sector of the continental foreland. The second one, the AMC, is composed of imbricated sedimentary sequences belonging both to two palaeogeographic domains (Tethys and Ionian basins) related to oceanic crust-type sectors, separated by the inner carbonatic platform located on continental crust type. The KCC originated by the delamination of the European margin. The Sardinia Block represents a remain of the European crust. The Tyrrhenian Basin is characterised by oceanic crust, and its opening started since Middle Miocene. Geological and Geophysical data allow to propose a palaeogeographic picture and to recognize three orogenic phases: the Eo-alpine, the Balearic and the Tyrrhenian stages. They developed respectively since Late Cretaceous-Eocene, to Oligocene-Burdigalian, up to Middle Miocene-Quaternary times. The whole structural architecture of the Apenninic-Maghrebian Orogen can be related to the distribution of these recognised oceanic and continental crusts. The progressive time-space migration of the thrust belt-foredeep system can be interpreted as a response of three subduction stages, the first, the Eoalpine Stage, in which the Afroadriatic margins overrode the eoalpine covers, the second one, the Balearic Stage, when the Alpine Tethys crust was consumed; during the third one, the Tyrrhenian Stage, the palaeo-ionian crust subducted and the modern collisional setting was reached. The interpretation of the CROP-MARE seismic lines in fact show that both the Foreland Blocks are in collision with a continental crust, the Panormide-Apenninic crust, recognised in the Tyrrhenian offshore respectively of the northern coast of Sicily and of the Southern Apennines and interpreted as the original basement of the carbonate platforms.