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Stratigraphy of the Messinian Sequences in the Deep Basin Setting of the Eastern and Western Mediterranean Basins

Abstract

Through several examples taken from both Eastern and western Mediterranean Sea, we show that the clastic input caused by sea level drop and marginal erosion, is not distributed evenly through time but mainly localized in the lower section of the Messinian mega sequence. Significant similarities from both side of the basin allow us to propose a global Messinian megacycle depositional scheme divided into three system tracts (1) a falling stage with marginal erosion and important shift of depocenter towards the basin, (2) a lowstand characterized by huge clastic deposition localized in front of major Messinian rivers (Rhone, Nile, Antalia gulf rivers) or smaller deltas (offshore south Lebanon). These clastics are deposited in an oversaturated (salt) basin as shown by the interfingering evaporites and clastics facies. (3) An Upper “transgressive” or late lowstand system tract constituted by halite, dolomitic marls, gypsum and sands in the distal part of the margins. This megasequence is a logical consequence of the progressive isolation of the Mediterranean basin during convergence. The results provide a new basis for discussion not only for the development of the Messinian Salinity Crisis but also for the reconstruction of the subsidence history of Mediterranean deep Basins and modelling.