The Messinian Sicilian stratigraphy revisited: new insights for the Messinian salinity crisis

Controversies around the Messinian salinity crisis (MSC) are because of the difficulties in establishing genetic and stratigraphic relationships between its deep and shallow-water record. Actually, the Sicilian foreland basin shows both shallow and deep-water Messinian records, thus offering the chance to reconstruct comprehensive MSC scenarios. The Lower Gypsum of Sicily comprises primary and resedimented evaporites separated in space and time by the intra-Messinian unconformity. A composite unit including halite, resedimented gypsum and Calcare di Base accumulated between 5.6 and 5.55 Ma in the main depocentres; it records the acme of the Messinian Salinity Crisis during a tectonic phase coupled with sea-level falls at glacials TG14-TG12. These deposits fully post-date primary gypsum, which precipitated in shallow-water wedge-top and foreland ramp basins between 5.96 and 5.6 Ma. This new stratigraphic framework results in a three-stage MSC scenario characterized by different primary evaporite associations: selenite in the first and third stages, carbonate, halite and potash salt in the second one associated with hybrid resedimented evaporites.