The end of the Messinian Salinity Crisis in the western Mediterranean: Insights from the carbonate platforms of south-eastern Spain |
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Authors: | Raphaël Bourillot Emmanuelle Vennin Jean-Marie Rouchy Marie-Madeleine Blanc-Valleron Antonio Caruso |
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Institution: | a Université de Bourgogne, Laboratoire Biogéosciences, 6 Bd Gabriel, 21000 Dijon, France b CNRS, UMR 5561, France c Department of Earth History, Museum National d'Histoire Naturelle, 43 rue Buffon, 75005 Paris, France d CNRS, UMR 7207, France e Università degli studi di Palermo, dipartimento di Geologia e Geodesia, via Archirafi 22, 90123 Palermo, Italy |
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Abstract: | How the Messinian Salinity Crisis (MSC) ended is still a matter of intense debate. The Terminal Carbonate Complex (TCC) is a late Messinian carbonate platform system that recorded western Mediterranean hydrological changes from the final stages of evaporite deposition till the advent of Lago-Mare fresh- to brackish water conditions at the very end of Messinian times. A multidisciplinary study has been carried out in three localities in south-eastern Spain to reconstruct the history of TCC platforms and elucidate their significance in the MSC. Overall, this study provides evidence that the TCC formed following a regional 4th order water level rise and fall concomitant with an opening-restriction trend. It can be subdivided into four 5th order depositional sequences (DS1 to DS4) recording two phases: (1) from DS1 to DS3, a tide-dominated ooidic to oobioclastic system with stenohaline faunas developed as a result of a 70 m water level rise. During this period, the TCC developed in a shallow sea with close to normal marine salinity; (2) in depositional sequence 4, a microbialite-dominated platform system developed. This is indicative of a significant environmental change and is attributed to a 30 to 40 m water level fall in the basins under study. These restricted conditions were coeval with intense evaporite deformation and brine recycling. The syn-sedimentary deformation of evaporites had a major impact on platform architecture and carbonate production, affecting the Messinian series throughout south-eastern Spain at the end of the TCC history. At that time, the TCC developed in a lake with fluctuating, brackish- to hypersaline water. These findings suggest a temporary restoration of marine conditions in the western Mediterranean marginal basins due to Atlantic water influxes prompted by a global sea level rise around 5.6 Ma. Whether marine conditions extended to the entire western Mediterranean still needs to be investigated. |
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Keywords: | Messinian Salinity Crisis Western Mediterranean Carbonate platforms Evaporite deformation and dissolution Eustasy Return to marine conditions |
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