20-EPN-038: UNDERCOOL –UNderstanding Deep Exchange Ratio of Carbon in the sOuthern Ocean during the Last deglaciation
Virtual visit by Francois Beny, Centre de Recherche et d’Enseignement de Géosciences de l’Environnement (CEREGE), Technopôle de l’Arbois-Méditerranée (France) to TA2.1 VU Geology and Geochemistry radiogenic and non-traditional stable Isotope Facility (GGIF).
Dates of visit: 10-19 February 2022
Report Summary: The ten days virtual visit permitted the successful acquisition of trace and rare earth element composition as well as Sr-Nd isotopic composition of 16 clay size terrigenous samples from core MD12-3396Q from the Indian sector of the Southern Ocean and East of the Kerguelen Plateau. Blank levels as well as MAG-1 geostandard composition are consistent with previous analyses on this sediment core carried out in 2018 by the project leader.
The new data confirm a general trend during the last glacial period: an important increase of the contribution of material from Antarctica during the Heinrich Stadial (HS) 1 and from the HS 3 to the HS 2 due to enhanced equatorward export of AntArctic Bottom Water (AABW) likely caused by increased AABW formation. During other intervals of the last glacial period, sedimentation was dominated by particles from the Kerguelen Plateau delivered by the Antarctic Circumpolar Current (ACC).
In addition, these new data highlight the occurrence of a third source of particles whose contribution starts during the deglaciation reaching a maximum during the Holocene. This source is possibly Africa, which would imply a more efficient transport of particles from Southern Africa to the Indian Ocean by the Agulhas retroflection and/or a southern migration of the Southern Ocean climatic fronts.