Increased input of circumpolar deep water-borne detritus to the glacial SE Atlantic Ocean

Abstract : Analysis of radiogenic isotopes in marine sediments can provide useful information on the provenance and transport of detrital material, directly relevant to paleoceanographic investigations. Here we show that the detrital Nd isotopic composition of recent SE Atlantic marine sediments matches the complex modern-day hydrography. In these same cores, glacial-interglacial isotopic variations are consistent with previous investigations (using different paleoceanographic proxies), which have shown that the relative influence of North Atlantic Deep Water (NADW) into the South Atlantic was reduced during glacial periods. In a novel departure, however, we also calculate the mass accumulation rates of terrigenous material delivered by each of Circumpolar Deep Water (CDW) and NADW to demonstrate that the accumulation of detritus delivered by CDW was enhanced significantly in the glacial South Atlantic. This enhanced transport flux could be explained by an increased flow of CDW into the glacial South Atlantic and/or an increased concentration of suspended terrigenous material transported by glacial CDW.