Astrochronology of Late Middle Miocene Mediterranean sections.

High-resolution cyclostratigraphy and calcareous plankton astrobiochronology have been obtained from the latest Langhian to the earliest Tortonian of the Mediterranean. The investigated areas (Malta, Tremiti, and Sicily) are located in different geological settings, and the three studied sections show different cyclicity. Direct correlation between the Laskar 90(1.1) solution of the insolation curve and the sedimentary cycle pattern occurring in the investigated sections showed that all the sedimentary cycles are forced dominantly by Milankovitch periodicity. This forcing is also reflected in the climate-sensitive data (CaCO3 content, and the relative abundance of the planktonic foraminifer Globigerinoides) as shown by the application of spectral and filtering analyses. The calibration provided astronomical ages for all the sedimentary cycles and bioevents recorded in the sections. In particular, an age of 13.59 Ma was obtained for the extinction level of Sphenolithus heteromorphus, which is the best event approximating the Langhian–Serravallian boundary and an age of 10.55 Ma for the first regular occurrence of Neogloboquadrina acostaensis, the event that better approximates the Serravallian–Tortonian boundary in the Tortonian type section