The Messinian salinity crisis in the Adriatic foredeep: Evolution of the largest evaporitic marginal basin in the Mediterranean

The recent release of a large number of subsurface geological data by the Italian Minister of Economic Development, including boreholes and seismic profiles, provided the occasion for a new assessment of the deposits associated with the Messinian salinity crisis (MSC) in the Adriatic foreland basin system and a new integration with the outcropping successions of the Apennines. In particular, the study of the Messinian evaporites allowed to reconstruct a new detailed palaeogeographic and palaeobathymetric framework for all the stages of the crisis. We identified the largest evaporitic marginal basin ever described for the Mediterranean hosting the precipitation of the primary shallow-water gypsum deposits (PLG, Primary Lower Gypsum) during the first stage of the crisis. During the second and third stages of the crisis, the PLG basin underwent uplift and erosion and the evaporite accumulation moved to the deeper part of the basin and was characterized by the deposition of the Resedimented Lower Gypsum unit including clastic evaporites, recycling the PLG ones, primary halite and terrigenous deposits. The distribution of the different evaporitic facies, was the basis for an improved reconstruction of the upper Miocene tectonic evolution of the Apennines thrust belt. Our results show a clear separation between shallower depocenters, located in the wedge-top and in the Adriatic foreland basins and characterized by MSC stage 1 PLG deposition, and deeper-water ones, located in the Adriatic foredeep and close to the Calabrian Arc, where MSC stage 2 terrigenous and gypsum-bearing clastic deposits and primary halite accumulated.