HR: 1340h
AN: PP33B-0950    [Abstracts]
TI: Age Models for Hemipelagites and Turbidites From the Cap Timiris Channel off Mauritania
AU: * Wien, K
EM: kwien@uni-bremen.de
AF: Research Center Ocean Margins, University of Bremen, P.O. box 330 440, Bremen, 28334 Germany
AU: Holz, C
EM: cholz@uni-bremen.de
AF: Research Center Ocean Margins, University of Bremen, P.O. box 330 440, Bremen, 28334 Germany
AU: Koelling, M
EM: koelling@uni-bremen.de
AF: Research Center Ocean Margins, University of Bremen, P.O. box 330 440, Bremen, 28334 Germany
AU: Schulz, H D
EM: hdschulz@uni-bremen.de
AF: Research Center Ocean Margins, University of Bremen, P.O. box 330 440, Bremen, 28334 Germany
AB: This study on sediments from a submarine channel system demonstrates that geochemical data allow reliable age-depth correlation even of highly turbiditic cores and is an attempt to improve our understanding of how turbidity processes are related to sea-level / climatic changes. The recently active Cap Timiris Channel System incises the continental margin off NW-Africa and is characterised by turbidite transport. Gravity cores from three levee sites and one intra-channel location (GeoB 8509) were analysed applying sedimentological and geochemical methods. The hemipelagites at Site GeoB 8509 are interrupted to approximately 45 % by turbidites. Downcore X-ray fluorescence analyses were performed on all cores in order to fit age models by correlating their elemental data to dated reference cores, once turbiditic sequences had been removed from the dataset. These age models, in turn, enabled us to reliably estimate emplacement times of the intercalated turbidites. Core GeoB 8502-2 from a levee position in the lower reaches of the Cap Timiris Channel System dates back to about 300 kyr. Except for one turbidite in the Holocene, turbidites in this core are linked to glacial stages. The highly turbiditic core GeoB 8509-2, on the other side, postdates to about 15 kyr and comprises Holocene and late Pleistocene sediments, including the African Humid Period (14.8-5.5 kyr) and the Younger Dryas cooling event. Turbidites in this core are associated especially with the rapid sea-level rise at the Pleistocene/Holocene transition, whereas they are less frequent subsequently. The three most recent turbidite events occurred approximately 2.5, 1.7, and 1.2 kyr ago, respectively.
DE: 9325 Atlantic Ocean
DE: 4835 Inorganic marine chemistry
DE: 4556 Sea level variations
DE: 4558 Sediment transport
DE: 3022 Marine sediments--processes and transport
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2004 AGU Fall Meeting