A magnetostratigraphic study of the onset of the Mediterranean Salinity Crisis; Caltanissetta Basin

Abstract: The Messinian 'salinity crisis ' marked a dramatic limatic change in the Mediterranean region. The timing and extent of this event remain controversial, with conflicting models ranging from predictions of rapid and catastrophic dessication of all of the Mediterranean basin at once, to progressive draw-down of sea-level causing gradua! onset of evaporite formation starting at the margins of the Mediterranean Sea. In this paper the preliminary magnetostratigraphy is described of two sections in the Neogene Caltanissetta basin, Sicily, containing the early Messinian Tripoli Formation, which pre-dates evaporite formation, and the overlying Calcare di Base shallow water carbonates that mark the first evaporite phase. The magnetisation of the sediments has been extensively overprinted by recent weathering, but primary or early diagenetic remanences which pass reversal and fold tests have been isolated. This has been possible because the sections have been tilted by Pliocene tectonic movements, hus rotating the pre-tilt remanence direction away from the later overprint direction, allowing resolution of the components bygreat circle analysis. The sections have been correlated with Krijsman et al.'s revision of the geomagnetic polarity time scale (GPTS) of Cande & Kent. This was achieved by comparin