GNGTS 2015 - Atti del 34° Convegno Nazionale

30 GNGTS 2015 S essione 1.1 propagated since about 125 kyr from the eastern flank of Mt. Etna to the offshore of NE Sicily. Our investigations point out that an impressive tectonic uplifting, affecting isolated crustal blocks, associated with the development and the progressive migration of the volcanism, from the Hyblean Plateau to the Aeolian Islands, heralded the reactivation and the propagation of the normal faults in eastern Sicily. The normal faults of south-eastern Sicily activated since ~330 kyr at the borders of a mobile crustal wedge that started to move and uplift since ~850 kyr. The normal faults of north-eastern Sicily propagated since ~125 kyr, along the margin of an actively uplifting crustal block which, in turn, started to move at ~600 yr. Our data also evidence that the mobilisation of block anticipated the onset of the volcanism at the leading edge of the moving crustal blocks (Fig. 3). This aspect, together with the mode and the rate of deformation along the bounding faults, suggest to relate the remobilization of the crustal blocks to upraising mantle wedges beneath these (see also Catalano et al. , 2010). It is remarkable that the process started at the main transform zone separating the subducting Ionian slab from the buoyant Hyblean continental crust, to the south of Mt. Etna. The opening of a mantle window along this transform zone has been proposed as the cause of the mantle plume which induced the Etna volcanism since 600 yr (Gvirtzman and Nur, 1999). This process matches the indication of a NE-ward remobilisation of the mantle beneath the continental crust of the adjacent Hyblean region, dragging the Siracusa Domain mobile block towards the Etna region since ~850 yr. The Etna volcanism started together with the remobilisation of the Peloritani Mobile Block that also marked the deactivation of the main dextral faults at the southern edge of Calabrian arc. The end of the strike-slip deformation could be strictly related to a NE-directed mantle flow fed by the mantle window. The activation of the flow paralleling the hinge of the Ionian subduction have supplied large volumes of materials, balancing the accommodation space due to the Ionian rolling back, thus causing the end of the dextral crustal shearing at the surface. The reconstructed tectonic evolution of eastern Sicily Fig. 3 – Sketch map illustrating the timing of the propagation of the mantle-flow beneath eastern Sicily and the relation with the volcanism and the crustal extension.