HR: 0800h
AN: PP41C-0680    [Abstracts]
TI: Response of the Surface and Deep Ocean to Abrupt Climate Events in the South East Atlantic Ocean During the Middle Brunhes
AU: * Dickson, A J
EM: a.dickson@ucl.ac.uk
AF: Environmental Change Research Centre, University College London Pearson Building Gower Street, London, WC1E 6BT, United Kingdom
AU: Bendle, J A
EM: james.bendle@ges.gla.ac.uk
AF: Department of Geographical and Earth Sciences, University of Glasgow East Quadrangle University Avenue, Glasgow, G12 8QQ, United Kingdom
AU: Leng, M J
EM: mjl@nigl.nerc.ac.uk
AF: NERC Isotope Geoscience Laboratory, British Geological Survey Kingsley Dunham Centre Keyworth, Nottingham, NG12 5GG, United Kingdom
AU: Maslin, M A
EM: mmaslin@geog.ucl.ac.uk
AF: Environmental Change Research Centre, University College London Pearson Building Gower Street, London, WC1E 6BT, United Kingdom
AU: Pancost, R D
EM: r.d.pancost@bristol.ac.uk
AF: School of Chemistry, University of Bristol Cantock's Close, Bristol, BS8 1TS, United Kingdom
AB: Recent work has shown that millennial-scale climate events punctuated many of the most recent glacial periods, and may have involved re-organisations of the Atlantic Meridional Overturning Circulation (AMOC). While numerical models often seek to understand how these events may have been manifested in locations outside of the North Atlantic Ocean, relatively little proxy data exists to test these simulations. New data has been produced from ODP-1085B (1713m water depth) in the South East Atlantic Ocean, and includes information on sea-surface temperatures, intermediate water hydrology, bottom water nutrients, and biological productivity. A preliminary age model is based on a visual correlation to the EPICA Dome C deuterium record plotted on the EDC-3 timescale and shows that the dataset extends from Marine Isotope Stage (MIS)-9 to MIS-13. Abrupt climate events punctuated MIS-12 and MIS-10, and resulted in moderate surface-water warming in the South-East Atlantic Ocean, associated with a southwards shift in the southern edge of the trade-wind belt (Intertropical Convergence Zone) and a reduction in the influence of southwards-flowing North Atlantic Deepwater (NADW) on bottom water hydrography. Carbon isotope values of deep-dwelling planktonic foraminifera and fine-grained bulk carbonates also suggest a possible shoaling of Antarctic Intermediate Waters in response to reduced NADW export during these events, but this remains a testable hypothesis with the current dataset. Within the constraints of the age- model the abrupt events are seen to be coincident with surface water cooling in the North Atlantic Ocean, suggesting a link to hydrographic forcing at sites of NADW production. The events are superimposed on glacial- interglacial shifts in the Southern Hemisphere frontal systems which promote large-scale changes in the mode of sedimentation at ODP-1085B.
DE: 4901 Abrupt/rapid climate change (1605)
DE: 4936 Interglacial
DE: 4940 Isotopic stage
DE: 4962 Thermohaline
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting