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

摘要

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.