High-resolution strontium isotope stratigraphy of the Messinian deep Mediterranean basins: Implications for marginal to central basins correlation

Abstract

New 87Sr/86Sr data from DSDP–ODP Messinian cores from deep Mediterranean basins suggest that the usually envisaged correlation of offshore Upper Evaporites with onshore Upper Gypsum deposits of Sicily, Cyprus and Crete recording the stage 3 (5.53–5.33 Ma) of the Messinian salinity crisis may be not entirely correct. High-resolution stratigraphic calibration of Sr isotope data indicates that only a very thin unit (commonly < 50 m) in the uppermost part of the “seismic” Upper Evaporites is characterized by the typically lower values for Sr isotopes with respect to the global Ocean which characterize stage 3 onshore successions (“Lago Mare event”). These deposits mainly consist of interbedded clastic or cumulate gypsum and marls; halite recovered from cores in the Upper Evaporites unit is actually characterized by Sr isotope values consistent with stage 2 deposits of onshore successions. According to these results, the Messinian trilogy of the western Mediterranean basin could be as a whole correlated with the halite unit of the eastern basin, suggesting that different hydrologic conditions characterized the two deep areas during the peak of the salinity crisis.