The Discovery of a Large-Scale Gravitational Collapse in the Gulf of Squillace, Calabria Region (central Mediterranean)

The discovery of a large-scale gravitational complex, named in this work Squillace Complex, has been reported in the Gulf of Squillace, Southern Italy, spanning from the continental shelf (c. 1.5 km from the coastline) to the distal sector, covering an area of roughly 600 km2. The integration between seismic reflection data, borehole and bathymetric information has revealed that this complex exhibits a NE-trending headwall domain made up of sinuous and continuous seafloor scarps linked to a E-W morphological high, via a basal detachment layer between the Messinian evaporites and Tortonian shaleys. The initiation of the Squillace Complex dates back to the Zanclean (~ 4 Ma) and persisted in movement through the Gelasian (~ 2.1 Ma) at an average rate of 1.9 mm/year. Later in the Calabrian (Middle Pleistocene), the movement underwent a braking and continued sliding to the present day at a reduced rate of 0.1 mm/year. The gravitational collapse of the Squillace Complex aligns temporally with distinct contractional/transpressional events impacting the Calabrian region. These events resulted from basin shortening under a setting of Calabrian Arc stop migration, as well as tectonic uplift affecting the study area since 0.45 million years ago. In contrast, the diminished movement observed in the Squillace Complex since the Calabrian (Middle Pleistocene) has been inferred as a consequence of conditions of basin stretching in the framework of Ionian plate rollback beneath the Calabrian Arc.