Organic Carbon and Nitrogen Isotopes of the Palaeocene-early Eocene: Implications on Stratigraphy, Paleoenvironment and Paleoclimatology

Abstract

This PhD focuses on organic carbon stable isotope geochemistry of particulate organic carbon (δ13Corg) during the Palaeocene and earliest Eocene. A huge number of isotopic analyses have been performed by the development of a robust organic carbon isotope methodology reliable for marine and continental settings. Thanks to this methodology, more than five hundreds samples have been analysed. A complete δ13Corg record is established for several sections encompassing the whole Palaeocene, giving a chemo-stratigraphic framework for this stage. Some “high resolution” analyses of this integrative proxy propose an accurate and precise stratigraphic reference mark for some short “transient” events like at Palaeocene Eocene boundary (PETM = Palaeocene Eocene Thermal Maximum) on one hand and at the Danian Selandian boundary on the other hand. Organic carbon isotope record developed in this PhD brings a supplementary dimension in the understanding of the carbon cycle variations at short and long-term for the Palaeocene and earliest Eocene interval. These records improve our knowledge of “short-term” (high-frequency) carbon isotope variations often comprised in a much more long-trend evolution (long-term, low-frequency) of the carbon cycle in marine as well as in continental settings. This proxy, associated to the nitrogen isotope of organics (δ15Norg), palynofacies, Rock-Eval analyses and magnetic susceptibility data allows possible the study of complex environmental and climatic phenomenons occurring before, during and after the carbon cycle perturbation, which affect the evolution of mammals, plants and other organisms. Geological research implied in the definition of stratigraphic boundary proposes here a powerful proxy, more and more precise, in the geological timescale, which improve our knowledge of this complex “greenhouse world” when associated to others proxies.

Date of Award	13 Jun 2013
Original language	French
Awarding Institution	University of Namur
Supervisor	Johan Yans (Supervisor), Vincent Hallet (President), Paola Iacumin (Jury), Florence Quesnel (Jury), Philip A MEYERS (Jury), Christian Dupuis (Jury), Thierry Smith (Jury) & Johann Schnyder (Jury)