Cycles of humid-dry climate conditions around the P⁄E boundary: new stable isotope data from terrestrial organic matter in Vasterival section (NW France)

Abstract : The Palaeocene ⁄ Eocene boundary (P ⁄ EB) and the Palaeocene- Eocene Thermal Maximum (55.8 Ma) are defined stratigraphically based on carbon isotope ratios of various materials. Here, the position of the P ⁄ EB is refined in the terrestrial-lacustrine and swampy Vasterival section (Upper Normandy coast, France) by using carbon isotopes measured on dispersed organic matter (d13Corg). Moreover, nitrogen isotopes on dispersed organic matter (d15Norg) are, for the first time in the Palaeogene record, associated with carbon isotope and lithological data to constrain palaeoclimatic and environmental changes around the P ⁄ EB in a terrestrial environment. Humid-dry fluctuations before and during this key interval in Earth history are suggested.