Comparison of independent proxies in the reconstruction of deep-water circulation in the South-East Atlantic off Namibia

Independent proxies were assessed in two Late Quaternary sediment cores fro m the eastern South Atlantic to compare deep-water changes during the last 400 kyr. Two cores were recovered from beneath North Atlantic Deep Water (N ADW) at approximately 3 000 m depth. Late Quaternary presence of NADW is in dicated by the Cibicidoides wuellerstorfi assemblage on the Walvis Ridge (C ore GeoB 1214) and the Bulimina alazanensis assemblage on the Namibian cont inental slope (Core GeoB 1710). The propagation of NADW is exclusively obse rved during interglacials, with maximum factor loadings in Stages 1, 5, 7, 9 and 11. These maxima are consistent with peaks in kaolinite/chlorite rati os and maxima of poorly crystalline smectite in the clay-mineral record. Ka olinite and poorly crystalline smectite are products of intense chemical we athering. They are injected into the NADW at low latitudes, north of the st udy area, and advected south. Chlorite, which is stable under cold weatheri ng regimes, is a characteristic mineral of water masses of southern origin. During glacial stages, it is advected north with Southern Component Water (SCW). Above the NADW/SCW depths, kaolinite/chlorite ratios vary only sligh tly without a significant glacial-interglacial pattern, as measured in a co re (GeoB 1712) from 1 000 m deep on the same profile of the Namibian contin ental slope off Walvis Bay.