A new large‑scale gravitational complex discovered in the Gulf of Squillace (central Mediterranean): tectonic implications

Seismic reflection (2D/3D), borehole and bathymetric data are used to recognize a new gravitational complex in the Gulf of Squillace, Southern Italy, named the Squillace Complex. The complex has a NE-striking headwall connected to a basal detachment formed between Messinian evaporites and Tortonian shales. Its sense of movement changes to a W–E direction in the toe region. In plan view, the Squillace Complex is marked by the presence of sinuous and continuous seafloor scarps, just a few kilometers offshore, over an elongated morphological high. Seismic-well ties reveal that the complex was initiated in the Zanclean (~ 4 Ma) and continued its movement into the Gelasian (~ 2.1 Ma) at an average rate of 1.9 mm/year. Movement slowed down in the Calabrian (middle Pleistocene) and continued until the present day at a lower rate of 0.1 mm/year. Gravitational collapse of the Squillace Complex correlates with discrete contractional/transpressional events affecting the Calabrian region, which caused basin shortening and the temporary arrest of Calabrian Arc migration. These episodes resulted in tectonic uplift in the study area after 0.45 Ma (Late Pleistocene). Conversely, the complex’s slower movement recorded since the Calabrian (middle Pleistocene) is associated with slab rollback of the Ionian plate under the Calabrian Arc.