Dre Sophie Sepulcre - Rapid deglacial injection of heat and nutrients in the Northeastern Atlantic Ocean from the Southern Ocean during the Heinrich Stadial 1

As part of the return flow of the Atlantic Overturning Circulation (AMOC), the Antarctic Intermediate Waters (AAIW) redistribute heat, salt and nutrients from the Southern Ocean (SO) to the North Atlantic and thus plays a key role in ocean-atmosphere exchanges. However, the dynamics of the AAIW during the Last Deglaciation remains unconstrained. We present new records of benthic foraminifera Cd/Ca, Mg/Li and 18O spanning the Last Deglaciation from a sediment core from the Iberian margin (997m; 37°05.56'N, 9°28.38'W). Over the Last Deglaciation, our data indicate a pronounced warming, an increase in nutrient concentrations and an increase in salinity at the studied site. Our data especially suggest that the Heinrich Event 1 split into two phases: i) first, an increased input of AAIW and ii) then, the invasion of Mediterranean Outflow Water. Our records bring new evidence for the deglacial reconnection of shallow and deep Atlantic overturning cells, and changes in the AAIW nutrient budget and heat distribution across the Atlantic Ocean.

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Solène POURTOUT1, Sophie SEPULCRE1, Frédéric HAURINE1, Giuseppe SIANI1, Élisabeth MICHEL2, Christophe COLIN1.

1. Université Paris-Saclay, CNRS, GEOPS 91400 Orsay, France
2. Laboratoire des Sciences du Climat et de l’Environnement (LSCE), Ormes de Merisiers, bât 714, 91190 Saint-Aubin, France