A new large-scale gravitational complex discovered in the Squillace Embayment (central Mediterranean): Tectonic and geohazard implications

Abstract

Seismic reflection (2D/3D), borehole and bathymetric data have led to the recognition of a new gravitational complex in the Squillace Embayment. Named as Squillace Complex, it has a NE-striking headwall connected to a basal detachment zone formed between Messinian evaporites and Tortonian shales. Its geometry changes to a W to E predominant movement in its toe region. The Squillace Complex is marked by the presence of sinuous and continuous seafloor scarps just a few kilometers offshore (minimum distance 1.5 km), which occur over a lobate-shaped elongated morphological high. Seismic-well ties show that the complex initiated its movement in the Zanclean and continued for ~ 2 Ma into the Gelasian, with an average rate of 1.6 mm /y. Movement ceased in the Calabrian but resumed soon later during Middle Pleistocene, until the present day, at a relative slower rate of 0.4 mm/y. The onset of gravitational collapse in the Squillace Complex is correlated with discrete contractional/transpressional events, under episodes of basin shortening and temporary stopping of Calabrian Arc migration, as well as during episodes of tectonic uplift after 0.45 Ma. Conversely, its arrest during the Calabrian is linked to slab rollback and subduction of the Ionian plate under the arc.