The Palaeocene ‘‘top chron C27n’’ transient greenhouse episode: evidence from marine pelagic Atlantic and peri-Tethyan sections

Abstract

The early Cenozoic, which is punctuated by several negative carbon isotope excursions (CIEs), was a time of climatic and oceanographic transition from ’Greenhouse’ to ’Icehouse’ conditions. The occurrence of a 0.5& CIE starting at the top of Chron C27n (TC27N) is reconfirmed with stable isotope data from Zumaia (Spain) and Bjala (Bulgaria) localities. Spectral analysis on respective carbonate ⁄magnetic susceptibility proxy records substantiates the orbital cyclostratigraphy allowing correlation to a high-resolution benthic foraminifera isotope record from ODP Pacific Site 1209, that indicates a coeval 2 C transient warming. The hyperthermal event lasts 200 ka, contrasting with other short-lived events from the Eocene, and displays a relatively rapid onset and a longer tailing back to pre-event values similar to the Palaeocene–Eocene Thermal Maximum (PETM), though lower in amplitude. That a causal trigger for the TC27N event may be the onset of volcanism in the North Atlantic Igneous Province (NAIP) can be inferred from a 200-m-thick lava pile erupted during C27n ⁄ C26r polarity transition in the E Greenland margin.