The pre-PETM perspective of transient paleoceanographic events

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The marine ecosystem has been severely disturbed by several transient paleoenvironmental events (<200 ky) during the early Paleogene, from which the Paleocene-Eocene Thermal Maximum (PETM, ~56 Ma) is the most prominent one. During these events the injection of isotopically light carbon into the ocean/atmosphere system resulted in a >1 per mil negative carbon isotope excursion, a substantial temperature rise as well as changes of the biota and in ocean chemistry. Until now two of the earliest events, the "Latest Danian Event" (LDE, ~61.75 Ma) and the "Mid-Paleocene Biotic Event" (MPBE, 58.9 Ma) have rarely been studied in the deep-sea. In this project we investigate the response of the planktic ecosystem to these perturbations. We test if these events are represented on a global scale and if they can be traced in various distinct environmental settings. Planktic foraminiferal assemblages from several ODP sites covering the Atlantic, Pacific and Indian oceans as well as from shelf deposits in Egypt are quantitatively assessed and statistically analyzed. Faunal analyses are supplemented by foraminiferal stable isotope studies (carbon and oxygen isotopes) to reconstruct the prevailing paleoceanographic conditions. This will also allow for establishing a high-resolution chemostratigraphic record complementing the biostratigraphy for the late Danian to Selandian interval. Finally, clay mineralogy is expected to indicate climate driven changes in weathering conditions on the adjacent continent and inorganic geochemistry is used to detail changes in the redox state of the oceans accompanying the studied events. The project is carried out in close co-operation with the KU Leuven, where the benthic ecosystem as represented by benthic foraminifera is studied on the same samples to assess the impact of these events on the entire water column.