Plio-Pleistocene strike-slip deformation in NE Sicily: the example of the area between Capo Calavà and Capo Tindari

The Peloritani Mts. in Northeastern Sicily are part of the Sicilian orogenic belt interposed between the Tyrrhenian basin and the Ionian Basin. In the Tyrrhenian basin crustal thinning has been active since the late Miocene, whereas wedge accretion (External Calabrian Arc) has occurred in the Ionian basin, due to the north-westward subduction of the Ionian Plate below the Calabrian-Peloritani Arc. Strike-slip tectonics in NE Sicily occurred during Plio-Pleistocene times. Faulting caused a non-uniform uplift rate of the Plio-Pleistocene deposits, which are elevated up to 500 m above sea level. The structural pattern is mainly represented by NW-SE and N-S/NNE-SSW trending transcurrent faults which form asymmetric tectonic depressions. Normal and reverse oblique-slip faults are associated with large-scale strike-slip deformation bends, and form releasing and restraining structures. The normal faults are mostly listric and flatten at very shallow levels, in places re-activating older thrusts. Transtension in the northern coastal sectors is southwards, counteracted by transpression, which is represented by high-angle reverse faults in the Peloritani thrust front. High seismic activity is mostly located within these bands, both on land and in the Tyrrhenian offshore, indicating active deformation processes. Focal solutions suggest that the Peloritani Mts. are characterised by extension and transcurrent kinematics in agreement with the stress field resulting from the orientation of the outcropping strike-slip structures. A cards-pack non-uniform rotation around a vertical axis in the Peloritani thrust stack is proposed to explain the geometrical pattern of the strike-slip faults. Within the main W-E trending shear zone, the minor structures result from simultaneous extension, transcurrent movement and compression in each band, transferring the strain from the Tyrrhenian sectors (dominated by crustal thinning) to the Peloritani thrust front.