The Terminal Carbonate Complex: the record of sea-level changes during the Messinian salinity crisis

Based on new cyclostratigraphic data and considerations, the Messinian Terminal Carbonate Complex (TCC), consisting of oolite and microbial-dominated carbonate platforms mainly preserved in the western Mediterranean basins, developed between 5.97 and 5.42 Ma. In Sorbas basin (southern Spain), the TCC offers an almost continuous record of MSC stages 1 (5.97-5.6 Ma), 2 (5.6-5.55 Ma) and of the lower part of stage 3 (5.55-5.42 Ma). As a consequence the TCC carbonate platforms can be considered as a shallow-water equivalent of both Lower Gypsum and Upper Gypsum units, developed respectively during MSC stage 1 and 3. The MSC peak during stage 2 caused a significant change in reef-builder communities allowing subdivision of the TCC into two units. TCC 1 dominated by oolites, Porites reefs and stromatolites and TCC 2, dominated by thrombolites. The surface separating the two units corresponds to the Messinian erosional surface; facies and stratigraphic relationships suggest that only a modest relative sea-level fall (tens of meters) can be associated to this unconformity, thus questioning the high-amplitude sea-level drop (800-1500 m) usually envisaged for this event which led to the accumulation of giant salt bodies in deep Mediterranean basins.