Structural framework and crustal characteristics of the Sardinia Channel Alpine transect in the central Mediterranean

The submerged area located between the Sardinia Channel and the western. Si cily offshore has been investigated based on deep crustal and conventional seismic lines with the aim of illustrating the relationships between the cr ust and its overlying crystalline and sedimentary thrust wedge. Analyses of seismic attributes and reflector pattern, supported by dredge hauls, also provided data in areas where stratigraphic and lithologic control is absent . Crustal geometries, tectonic processes and timing of the deformation are discussed here. North of the Elimi chain (central Sardinia Channel) the reflecting body con sists of superposed tectonic wedges of crystalline rocks and their Meso-Cen ozoic carbonatic and terrigenous cover (Sardinian and Kabilian-Calabrian un its). The Kabilian-Calabrian units overthrust the Maghrebian-Apenninic unit s along the Drepano thrust front (Elimi chain), which is traceable on-land in eastern Sicily (Nebrodi-Peloritani Mountains). This lineament roots on t he crustal-mantle discontinuity, where the local superposition of two diffe rent crusts occurs. The thrust front of the crystalline Kabilian-Calabrian units marks the boundary between thick-skinned and thin-skinned tectonics i n the chain. The Apenninic segment of the chain develops between the Elimi sector and th e Sciacca offshore (south-west Sicily). The crust is not as thick as expect ed in Alpine chain areas, suggesting pre-orogenic thinning of the African c ontinental crust. The accretionary wedge is a southeast-vergent embricate f an consisting of four groups of thrust units formed by carbonate basinal an d platform ramps with duplex geometries. The Mesozoic carbonate units are d etached from the crystalline basement not involved in the deformation. The Tertiary terrigenous rocks are their roof thrust. The Upper Miocene clastic -terrigenous successions, sealing most of the structures, appear, in turn, detached and piled up. The intramountain Plio-Pleistocene basins display te ctonic features that point out the area underwent both extensional and cont ractional tectonics. (C) 2001 Elsevier Science B.V. All rights reserved.