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Sedimentological and paleoenvironmental scenario before, during, and after the Messinian Salinity Crisis: The San Miguel de Salinas composite section (western Mediterranean) Highlights 1) The sedimentary record is divided into three synthems: Messinian I (pre-evaporitic), Messinian II (syn-evaporitic), and Pliocene (post-evaporitic). 2) Marls associated with gypsum beds (syn-evaporitic phase) record dwarf planktonic foraminifera. 3) The syn-evaporitic phase (chron 3Cr) records major changes in water salinity in a stressed marine environment. 4) Two erosional surfaces correspond to the intra-and end-Messinian unconformities. 5) The end-Messinian unconformity is represented by an incised paleovalley.

The Neogene Fortuna and Bajo Segura basins are located on the northeastern end of the Trans-Alborán Shear Zone (TASZ), on the eastern Betic cordillera. The stratigraphic study of the infilling of these basins has shown two major sedimentary discontinuities. The first one, represented by an erosive surface separating open marine marls from an overlying coastal conglomeratic unit, is linked to the onset of the activity along the TASZ, which in this area indicates the beginning of the Abanilla Thrust emplacement. In the Fortuna Basin, the Tortonian salinity crisis, registered over this older first discontinuity, was therefore related to tectonic processes of the eastern portion of the cordillera and consequently would not have an expression in the western basins. The age of the Tortonian Salinity Crisis has been established with nannofossil biostratigraphy as Latest Tortonian at a somewhat lower stratigraphic position than previously recognized. The second sedimentary discontinuity was developed in relation with the known Mediterranean-wide Messinian salinity crisis.