Kaolinite and Chlorite as Tracers of Modern and Late Quaternary Deep Water Circulation in the South Atlantic and the Adjoining Southern Ocean

Late Quaternary variability of ocean circulation in the southeastern South Atlantic inferred from the terrigenous sediment record of a drift deposit in the southern Cape Basin (ODP Site 1089)

“…Latest reconstructions from icecore data and marine proxy records from the southern hemisphere indicate changes in atmospheric CO 2 and variations in air and sea-surface temperatures to have preceded changes in global ice volume on short and long time scales (Charles et al, 1996;Little et al, 1997;Blunier et al, 1998;Brathauer and Abelmann, 1999;Vidal et al, 1999). This phase lead on the Milankovitch time scale is not evident from our data, which suggest a more or less synchronous response of regional conveyor circulation to global ice-volume changes, as also inferred from other sediment records in the southeastern South Atlantic by means of clay mineralogy (Diekmann et al, 1996(Diekmann et al, , 1999. On the other hand, the inferred short-term £uctuations in conveyor circulation during MIS 3 correspond to air-temperature changes recorded in the Vostok ice core, when using a SPECMAP age model for both records.…”

“…Peak values appear in MIS 12 and MIS 10 (9.78 and 9.62 g cm 32 kyr 31 ) as well as in MIS 11 (7.4 g cm 32 kyr 31 (Froelich et al, 1991;Diekmann et al, 1999), the MAR Terr values at the drift Site 1089 are high and apparently point to elevated £uxes and focusing e¡ects of terrigenous matter induced by bottom-current action. In the entire Atlantic sector of the ACC, MAR Terr was usually higher during glacial periods (Diekmann et al, 1999. At Site 1089, such clear glacial^interglacial contrasts are only evident for the MIS 12 to MIS 10 interval.…”

“…Moreover, we calculated mass-accumulation rates of terrigenous silt and clay (MAR Silt , MAR Clay ), according to their weight proportions in the samples. Mass-accumulation rates of kaolinite and chlorite (MAR Kao , MAR Chl ) were estimated from MAR Clay values and the relative proportions of the individual clay minerals, under the assumption that beside quartz and feldspar, clay minerals generally make up 80% of the clay fraction in sediment cores of the southeastern South Atlantic (see Diekmann et al, 1999).…”

North Atlantic Deep Water and Antarctic Bottom Water variability during the last 200ka recorded in an abyssal sediment core off South Africa

“…Accordingly, NADW is showing higher K/C than AABW. In warm periods, a stronger influence of NADW in the Agulhas Basin is evidenct from high values of δ 13 C and K/C (Diekmann et al, 1996;Diekmann et al, 1999;Krueger et al, 2008. ) In contrast, Cd/Ca and 231 Pa/ 230 Th measurements on sediments from the Southern Ocean indicate that NADW influx did not change much over the last glacial/interglacial cycles (Lea and Boyle, 1990;Boyle, 1992;Yu et al, 1996;Marchal et al, 2000).…”

Distribution of clay minerals in surface sediments of the Aegean Sea: a compilation

“…Based on these studies, clay mineral assemblages from sediment cores have been applied to the reconstruction of past weathering processes and circulation patterns (e.g. Chamley 1989 and references therein; Ehrmann et al 1992;Gingele 1995;Diekmann et al 1999).…”