Enrichments in authigenic uranium in glacial sedimens of the Southern Ocean

International audienceFour sediment cores from the Polar frontal zone and the Antarctic zone in the Indian sector of the Southern Ocean present an increase of authigenic uranium during glacial periods. We show that this increase in uranium is due to a combination of (i) an increase in the lateral transport of organic matter, (ii) a decrease in the oxygen in deep waters, and (iii) a process of diagenesis. It appears that uranium concentration cannot be used as a proxy of palaeoproductivity in the Southern Ocean, as previously suggested by Kumar et al. in 1995. © 2002 Acade?mie des sciences / E?ditions scientifiques et me?dicales Elsevier SAS