RECOGNIZING THE CLASTIC EVAPORITE REALM, THE EXAMPLE OF THE MESSINIAN FROM THE MEDITERRANEAN BASIN

The understanding of saline giant basins has been hampered by the lack of modern analogues and this is particularly true for the Messinian salinity crisis of the Mediterranean basin (about 6 Ma; Roveri et al., 2014a). The recognition of clastic evaporites in the Mediterranean was introduced very early in the Messinian debate (Hardie and Eugster, 1971; Parea and Ricci Lucchi, 1972; Schreiber, 1973), but its importance was neglected due to the overwhelming popularity of the Mediterranean desiccated deep basin model (Hsü et al., 1973). On the other hand, the widespread presence of clastic evaporites seem to testify for continuous subaqueous deposition and provide grounds for an alternative explanation of the facies formed during the salinity crisis (Roveri et al., 2014b). We have documented a complete transition from higher to lower density gravity-driven deposits, debris flows, slumps and olistostromes containing up to mountain-sized slabs of massive selenite in Sicily, Northern Apennines, Cyprus, Greece, Israel and Spain (Manzi et al., 2005; Lugli et al., 2013; Manzi et al., 2015). These deposits are not the result of subaerial erosion but, more likely, of submarine mass-wasting processes. The primary evaporites were dismantled from shallower thrust-top basins and resedimented to deeper areas as a consequence of large-scale submarine collapse and glide structures triggered by tectonically-induced gravitational instability. Clastic subaqueous evaporites have been also documented in deeper Mediterranean successions which were previously interpreted as supratidal deposits, questioning the occurrence of major sea level fluctuations during the salinity crisis (Hardie & Lowenstein, 2004; Lugli et al. 2015).

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