HR: 15:15h
AN: PP52B-07 INVITED     [PDF]
TI: De-coupled upwelling, productivity, surface water pCO2 of the Benguela Current System During the Intensification of Northern Hemisphere Glaciation.
AU: * Maslin, M
EM: mmaslin@geog.ucl.ac.uk
AF: University College London, Department of Geography 26 bedford Way, London, WC1H0AP United Kingdom
AU: Berger, W
EM: wberger@ecsd.edu
AF: Scripps Institution of Oceanography, Univeristy of California at San Diego, La Jolla, CA 92093 United States
AU: Boot, C
EM: c.boot@bristol.ac.uk
AF: Bristol University, Organic Geochemistry Unit Biogeochemistry Research Centre School of Chemistry, Bristol, BS8 1TS United Kingdom
AU: Denison, S
AF: University College London, Department of Geography 26 bedford Way, London, WC1H0AP United Kingdom
AU: Ettwein, V
EM: v.ettwein@ucl.ac.uk
AF: University College London, Department of Geography 26 bedford Way, London, WC1H0AP United Kingdom
AU: Murray, R W
EM: rickm@bu.edu
AF: Boston University, Department of Earth Sciences 675 Commonwealth Ave, Boston, MA 02215 United States
AU: Stickley, C
EM: cathy@earth.cf.ac.uk
AF: Cardiff University, School of Earth Science, Cardiff, CF10 3YE United Kingdom
AU: Wefer, G
EM: gwefer@allgeo.uni-bremen.de
AF: University of Bremen, Faculty of Earth Sciences, Bremen, 28334 United Kingdom
AB: The Intensification of the Northern Hemisphere Glaciation (3.2 to 2.5 Ma) is a key climatic transition in Earth History. Deep-sea sediments recovered from ODP Leg 175 Site 1083 cover this important time period and provide a means of monitoring the Benguela Current Upwelling system and the adjacent African continent. With a resolution of approximately 1 ka, we have reconstructed the following climatic parameters: Global ice volume (benthic foraminifera oxygen isotopes), wind strength and land aridity (HIRM, MS, Al/Ti ratios), upwelling intensity (UK37'-SSTs), surface water productivity (TOC, Chaetoceros resting spores, alkenone abundance, pigments, Ba), surface water nutrient availability (organic nitrogen isotopes), nutrient source (diatom species abundance), land vegetation type (n-alkane abundance and carbon isotopes) and surface water pCO2 (alkenone and calcite carbon isotopes). Three conclusions have been drawn from this unique data set: 1. Surface water productivity is not associated directly with increased glacial upwelling. Peaks in productivity occur during early glaciation, and full glacial productivity is lower than the interglacial levels. It is suggested that this is caused by the antagonistic effects of upwelling intensity and nutrient supply from the Southern Ocean. 2. Surface water pCO2 is relatively insensitive to changes in upwelling and productivity, suggesting the Benguela current is continuous sink of atmospheric carbon dioxide throughout a glacial-interglacial cycle. 3. South West Africa vegetation co-varies with precession and is independent of glacial-interglacial cycles. We suggest that this is due to the strong influence of precession on the southward penetration of the ITCZ and thus moisture availability.
DE: 4267 Paleoceanography
DE: 4279 Upwelling and convergences
DE: 4806 Carbon cycling
DE: 4825 Geochemistry
DE: 9604 Cenozoic
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2003 Fall Meeting