Tectono-stratigraphic evolution of the offshore Apulian Swell, a continental sliver between two converging orogens (Northern Ionian Sea, Central Mediterranean)

The Calabrian Arc subduction complex, in the northern Ionian Sea, is facing directly the westward subducting Apulian Swell, a sliver of continental crust covered by about 8 km of Mesozoic and Tertiary carbonates. Deformation patterns of this southernmost foreland segment of the Adria plate, analized from marine geological/ geophysical data include: 1) flexure/bending, under the load of the advancing Calabrian Arc wedge; 2) buckling in response to compression of the surrounding orogens (southern Apennines, Dinarides-Hellenides); and 3) rollback and eastward retreat of the slab. In this work, a reprocessed dataset of marine seismic reflection profiles is used to determine the interplay between these tectonic processes during progressive advancement of the Calabrian Arc wedge since Pliocene times. Our analysis indicates that the wedge is presently affected by compressive tectonics along several fore-thrusts, forming an imbricate fan system. Conversely, the Apulian Swell affected by inherited and rift-related Permo-Triassic normal faults, shows transpressive and positive tectonic inversions and, in its southern portion, the effects of the Hellenic fold/thrust belt shortening. The interference between the Calabrian Arc and the Hellenic chain plays an important role in controlling the tectono-stratigraphic evolution of the Apulian Swell, which underwent bending and roll-back during a pre-middle Pliocene stage followed by buckling processes. Active extension observed in the hinge zone of the Apulian Swell between Calabrian Arc and the Hellenides might suggest recent reactivation of flexure and retreat.