The Gelasian GSSP at Monte San Nicola (Sicily, Italy): New High-Resolution Multiproxy Data and Stratigraphic Continuity of the Type Section

Monte San Nicola (MSN) in Sicily (Italy) hosts the Global boundary Stratotype Section and Point (GSSP) for the Gelasian Stage and Quaternary System. Within the SQS-ICS GELSTRAT project, the functionality of the GSSP has been significantly enhanced through the acquisition of new high-resolution, multidisciplinary datasets. These demonstrate the continuity of the stratigraphic record and provide a robust chronostratigraphic framework based on the astronomical tuning of sapropelic layers to insolation maxima, and supported by integrated field, biogeochemical, and mineralogical analyses. The multiproxy climate reconstruction across the boundary – based on oxygen isotopes, alkenones, calcareous plankton, and pollen – defines a detailed climatostratigraphic framework spanning Marine Isotope Stage (MIS) G4 to the onset of MIS 99 (2.7–2.5 Ma). The record documents interactions between low- and high-latitude climate systems, including variability in the African summer monsoon and North Atlantic forcing. A pronounced southward migration of the Subarctic Front during MIS 104, evidenced just below the GSSP, aligns with North Atlantic records and coincides with strengthened winter monsoon conditions over the Chinese Loess Plateau. Here, we further expand the MSN dataset by presenting a new high-resolution benthic oxygen isotope record, which further confirms both the stratigraphic integrity and thickness reliability of the section. Concerns regarding stratigraphic continuity and tectonic disturbance across the GSSP are therefore not supported by the available analytical evidence. Although the entire MSN area is affected by pervasive faulting, displacements are readily identifiable in the field and can be avoided by focusing on the most continuous exposures. We reassert that the MSN GSSP type section remains the primary chronostratigraphic reference for the Gelasian Stage GSSP: continuous, well constrained, and ideal for local, regional and global correlation. Since the establishment of the GSSP in 1996, it has remained well preserved, accessible, and suitable for continued investigation by the scientific community, ensuring the stability of the geological time scale.