High-resolution climate variability across the Piacenzian/Gelasian boundary in the Monte San Nicola section (Sicily, Italy)

The Piacenzian – Gelasian transition is a time of profound changes in the Earth’s climatic regime, epitomized by the definitive establishment of large ice caps in the Northern Hemisphere and the beginning of the “ice ages” at ca. 2.6 Ma. This event is sharply documented in δ18O records globally by a prominent triplet of severe glacial events (MIS 100, 98 and 96) that approximate the base of the Gelasian Stage. We have reconstructed a multispecies planktic and benthic foraminiferal δ18O and δ13C record from the Monte San Nicola section (Sicily) across the Piacenzian/Gelasian boundary, with the purpose of better constraining in time the main marker criteria for recognition of the Gelasian GSSP (Global Boundary Stratotype Section and Point) and investigating in detail the paleoclimatic and paleoceanographic response of the central Mediterranean to the definitive onset of the Northern Hemisphere Glaciation. Our results confirm the reliability and usability of the criteria originally proposed for defining the Gelasian GSSP, and significantly improve their chronology and chronostratigraphic positioning. Beyond an obvious alternation of obliquity-driven glacial-interglacial cycles, our isotopic record unraveled a pervasive climate variability in the suborbital time domain, the origin of which is still ambiguous. Altogether data presented in this paper provide the first high resolution isotopic records shedding new light both on the stratigraphic and paleoclimatic evolution of the Central Mediterranean area at the beginning of the Northern Hemisphere Glaciation.