Stratigraphy of early to middle Eocene hyperthermals from Possagno (Southern Alps, Italy) and comparison with global carbon isotope records

Abstract

The late early Eocene to middle Eocene ~51–45 Million years ago (Ma) time interval in the middle bathyal, pelagic/hemipelagic succession of the western Tethys Possagno section in the Carcoselle quarry (Southern Alps, northeastern Italy), contains several episodes of negative carbon isotope excursions (CIEs) and concomitant dissolution of carbonates. Comparison with previously published carbon isotope records from deep-sea successions allows the identification of long-term trends and short-term events in our record, which provides a sound chemostratigraphic basis for correlation against the robust bio- and magnetostratigraphic scheme available for the studied succession and additional evidence of the global significance of the long-term trend and superposed perturbations tracked changes in δ13C values.Spectral analysis indicates that CIEs and associated lithological cycles are paced by orbital forcing, similar to what previously observed on the same interval in other deep-sea successions. The identification of astronomically forced geochemical cycles allows us to develop an orbitally tuned age model allowing to test the astrochronology of the ~56.0 Ma to ~47.5 Ma time interval.