Paleogeographic and sedimentary evolution of North Calabrian basins during the Messinian Salinity Crisis (South Italy)

The Rossano and Crotone basins in North Calabria represent key areas for the study of the Messinian Salinity Crisis (MSC) in the central Mediterranean. The integrated analysis of the outcropping successions coupled with well-borehole stratigraphies and seismic profiles permitted the stratigraphic and paleogeographic reconstruction of the MSC as follows: During the late Tortonian-early Messinian, open normal marine conditions typified the studied basins, as the deposition of deep-water claystones followed by diatomites (Tripoli Fm). The first basin restriction occurred during the early Messinian (5.96 Ma) when a relative sea-level still-stand triggered the formation of a carbonate platform system (Calcare di Base Fm − CdB). This latter was characterized by sabkha to shallow-water environments passing into a gentle slope to basin setting. A successive relative sea-level drop (ca. 5.60 Ma) induced a general exposure of the CdB platform systems and the creation of a marked erosional surface linkable with the Messinian Erosional Surface (MES). Consequently, progradational early LST forced regression wedges deposited and, as the reduction of open-sea connections, more severe restricted conditions took place. Later on, during the late LST, the massive deposition of salt dominated bodies brought to the sedimentary filling of the basins and to the consequent leveling of the paleobathymetric differences. Afterwards, a transgression phase (TST) inundated again the basins, causing firstly the sedimentation of clay dominated deposits, and successively, during a further sea-level still-stand (HST), the reestablishment of evaporitic conditions with deposition of widespread shallow-water sulphate deposits. Lastly, a new severe sea-level drop (LST) exposed again all the previous deposits and alluvial conglomerates deposited along incised paleovalleys above the HST sulphate deposits. This event marks the transition to the Lago-Mare phase that typifies the last stage of the MSC, before the base-Pliocene reflooding of the Mediterranean (ca. 5.33 Ma).