GNGTS 2015 - Atti del 34° Convegno Nazionale

28 GNGTS 2015 S essione 1.1 Fig. 2 – Main Quaternary tectonic and volcanic features of eastern Sicily. The Siracusa Domain is contoured by a flight of Late Quaternary marine terraces, that have been assigned to the Oxygen Isotope Stages (OISs) from 21 (850 kyr) to 3 (60 kyr). The geometry of these marine platform constrain a regional scale tilting associated to a tectonic uplift, faster than the adjacent sectors, which was regularly increasing towards the NNW, in the direction of the active thrust and fold system controlling the northwestern margin of the block (Bonforte et al. , 2015). The rate of deformation measured along the bordering structures indicate that the amounts of contractional-rate along the northwestern border of the block, estimated at about 1.2 to 1.3 mm/a (Catalano et al. , 201), has been completely accommodated by the 1.4 mm/a rate of left-lateral motions along the western border (Scicli Line; Catalano et al. , 2008b) and by the 1.3 mm/a extension-rate, which has been measured along the southeastern edge (Avola Fault; Catalano et al. , 2010). The kinematics of the borders of the Siracusa Domain are consistent with the NNW-SSE oriented compression which has been obtained by inversion of seismological data (Musumeci et al. , 2005) and fit the residual GPS velocity relative to Eurasia, with respect to rest of the foreland domain (Bonforte et al. , 2015). Mt. Etna region . In the Mt. Etna region, the contractional domain at the northern margin of the Hyblean Plateau is abruptly interrupted by a NW-SE oriented alignment, marked by dextral active fault segments, that represents the onshore prolongation of the Africa-Ionian tectonic boundary, recognised by seismic lines in the offshore of Catania (Fig. 2) (Nicolich et al. , 2000). The crustal significance of this tectonic boundary, already interpreted as a transform zone (Catalano et al. , 2004), is demonstrated by a N-S trending seismic line across the volcano (Cristofolini et al. , 1978) that shows a sharp increase of the depth of the Moho, almost corresponding to the location of the alignment. The southern portion of the seismic line, crossing the contractional domains, shows the continental crust of the African margin, flooring