Onshore to offshore correlation of regional unconformities in the Plio-Pleistocene sedimentary successions of the Calabrian Arc (central Mediterranean)

Three regional unconformity surfaces typify the Plio-Pleistocene fill of the onshore to offshore basins of the Calabrian Arc, an arcuate terrane migrating to the SE above the NW subducting Ionian lithosphere, between the southern Apennines and Sicily. These unconformity surfaces formed in the mid-Pliocene (late Zanclean to early Piacenzian), the early Pleistocene (intra-Gelasian) and the mid-Pleistocene (late Calabrian). Their expression varies significantly across the area, so that from one to three unconformities may be recognized within any given basin. Several lines of evidence suggest that the spatially variable development of the unconformities across the Arc records interruptions of subsidence by phases of uplift and deformation, related to the extent and nature of successive tectonic events linked to episodic subduction zone retreat and slab fragmentation during the Plio-Pleistocene interval. In particular, the mid-Pliocene unconformity is associated with uplift and deformation on the Ionian flank of the Calabrian Arc that interrupted a phase of basin subsidence coeval with opening of the Vavilov back-arc basin, and may record either interference of the Arc with the Apulian microplate, or an episode of out-of-sequence tectonic thickening within` the advancing accretionary wedge. The two Pleistocene unconformities bracket a phase of basin collapse in northern Calabria that coincides with the ultra-fast opening of the Marsili backarc basin, and are associated with uplift and contractional–transpressional deformation that record interference of the subducting slab with adjacent microplates. The recognition of a synchronous development of unconformities in the Calabrian basins provides key references for further studies of the geodynamic evolution of the central Mediterranean.