EGU General Assembly in Viena, Austria, 7–12 April 2019The establishment and evolution of the Antarctic Circumpolar Current (ACC) throughout the Cenozoic remainspoorly known, mainly because of the lack of continuous long-term records at strategic locations. Here we presentnew records from marine sediments collected by the Deep Sea Drilling Project (DSDP) Site 278, located in theSouthwestern Pacific sector of the Southern Ocean (Southern Emerald Basin), spanning from the mid-Oligoceneto the Pleistocene (ie. the∼28-2 Ma). Our site is ideally situated to reconstruct changes in the ACC sincethe mid-Oligocene as it remained along the polar frontal zone as shown by paleolatitude reconstructions andmicrofossil assemblage data. To track its evolution, we combined (i) mean grain size of sortable silt (SS) datawith (ii) primary productivity proxies including biogenic silica (BSi), calcium carbonate (CaCO3) and organicmatter, and (iii) neodymium isotope ratios (εNd) generated from fossil fish teeth and debris. Our results documenta significant increase in SS, enhanced marine productivity and a decrease inεNd values towards present-dayCircumpolar deep waterεNd values, suggesting a progressive strengthening of the proto-ACC flow over the last28 Ma. However, we find that the development of a modern-like, homogenous and deep-reaching current wasfully established solely during the Pliocene-Pleistocene transition, concomitantly with the onset of the NorthernHemisphere glaciation
