The Messinian Salinity Crisis: New seismic evidence in the West-Sardinian Margin and Eastern Sardo-Provençal basin (West Mediterranean Sea)

We processed and interpreted a newly acquired geophysical dataset (WS10 project) integrated with vintage seismic profiles to study the evolution of the Sardinian passive margin of the Sardo-Provençal basin. The most prominent features of the area of study are a consequence of the Messinian Salinity Crisis (MSC) which produced a thick salt layer in the deep basin. Complex halokinetic tectonics deformed the overlying Messinian Upper Unit (UU) and the Pliocene–Quaternary (PQ) sediments, sometimes also bending the sea bottom. A thinner autochthonous salt in the UU suggests at least one further low stand during the late MSC. The Messinian Erosional Surface (MES) separates the erosional truncation of the pre-Messinian sedimentary sequence from the overlaying Plio-Pleistocene sequence with a clear angular discordance, which almost completely masks possible earlier erosional events. The MES is present across the middle and upper slopes of the Sardinian margin and can be easily recognized down to the lower slope, where it interfingers with the Messinian evaporites which gradually thicken basinward. We propose a correlation between the main erosional surface of the lower slope and the salt layer recognized in the UU as a consequence of a falling stage during the last part of the MSC. The seismic profiles now available along the West Sardinian margin provide novel and crucial information to correlate the Messinian depositional units in the deep basin with those present in the lower continental slope and with the erosional surface of the middle and upper slopes. Our data and interpretation highlight the main units of the Messinian trilogy and further internal sequences that are probable related to cyclic fluctuations during their deposition.