Paleoceanography and paleocirculations

We are developing new methods for reconstructing past ocean circulation and oxygenation, using an approach based on a combination of geochemical approaches (isotopic compositions of neodymium and carbon in foraminifera) applied to the same ocean archive in order to minimise the biases associated with each approach. These approaches are at the heart of the ANR MedSens (2020-2024) project led by Kazuyo Tachikawa, which focuses on the study of Mediterranean thermohaline circulation. The ANR ITCH project (2023-2027), led by Clara Bolton, capitalises on the data from the SCRATCH French Oceanographic Fleet campaign (2021) to study the evolution of the Indian dipole and the co-evolution of oceanic plankton in the Mozambique Channel during the Pleistocene, and will complement our ongoing studies in the tropical Indian Ocean. The very precise 14C ages measured on benthic foraminifera as part of the ANR MARCARA project, led by Edouard Bard, will enable us to reconstruct deep ocean circulation.
The latest developments in automated micropalaeontology within the team have made it possible to initiate work on the past variability of surface hydrological conditions in the Indian Ocean, an important zone that contributes to climate variability on a global scale (ENSO, Indian Dipole, Monsoon). The application of our microfossil counting prototype (MiSo) to sediment samples taken from marine cores will make a significant contribution to this type of study. The development of this automatic sorting method will be continued over the next term with the A*Midex MicroTree project (2023-2025) led by Thibault de Garidel for the development of a second very high-speed sorter, and by the Equipex-+ IMAGINE2 (2021-2028) including a third automatic sorter combined with an X-ray sensor for microparticle screening (collaboration with the ED team).
This work is based on the numerous marine archives stored at CEREGE as part of projects supported by the supervisory bodies and internally. Our archives will soon be supplemented by a more complete spatial coverage of the tropical Indian Ocean (DipoMouss campaign, programmable P1) and by the TransPac federative campaign project aimed at obtaining a complete sub-equatorial zonal transect of Plio-Pleistocene sedimentary cores.