A review of basin-wide calcareous nannofossil bioevents in the Mediterranean at the onset of the Messinian salinity crisis

During the Messinian (7.2–5.3 Ma) the Mediterranean area experienced fast and deep climatic and eustatic structural changes. The stratigraphic framework for this interval is relatively well constrained and the beginning of the Messinian salinity crisis (MSC) dated at 5.971 Ma suggests a duration of at least 1.2 Ma for the pre-evaporitic Messinian that is the object of this study. A number of sites (Faneromeni, Pissouri, Polemi Basin, Kalamaki, Falconara, Fanantello, Lemme, Pollenzo, Govone, Moncalvo: Blanc-Valleron et al., 2002; Wade and Bown, 2006, Kouwenhoven et al., 2006; Morigi et al., 2007; Lozar et al., 2010, 2018; Dela Pierre et al., 2011, Karakitsios et al., 2017) show similar behaviour of the calcareous nannofossil record where several peaks of Sphenolithus spp. are recognised at different levels in each of the section. This paper compares the calcareous nannofossil data from six different sections across the Northern and Eastern Mediterranean area encompassing the onset of the MSC. Interestingly, a tight succession of bioevents (Sphenolithus abies, Helicosphaera carteri, Umbilicosphaera rotula, Rhabdosphaera spp.) is recorded in all the sections analysed and appears to correlate precisely among the investigated sites, approximating the onset of the Messinian salinity crisis, thus offering the possibility to use these as bioevents for regional correlation.