HR: 10:50h
AN: PP12A-03    [Abstracts]
TI: MILLENNIAL-SCALE VARIABILITY IN MEDITERRANEAN OUTFLOW IN THE GULF OF CADIZ: INSIGHTS FROM BENTHIC MG/CA AND BA/CA
AU: * Martin, P
EM: pmartin@uchicago.edu
AF: University of Chicago, Department of the Geophyiscal Sciences, chicago, IL 60637
AU: Voelker, A
EM: avoelker@softhome.net
AF: Geologia Marinha, Estrada da Portela, 2720, Alfragide, 000000 Portugal
AU: Lebreiro, S
EM: susana.lebreiroineti.pt
AF: Geologia Marinha, Estrada da Portela, 2720, Alfragide, 000000 Portugal
AU: Abrantes, F
EM: Fatima@net.vodafone.pt
AF: Geologia Marinha, Estrada da Portela, 2720, Alfragide, 000000 Portugal
AB: The Mediterranean Outflow (MOW) is a prominent feature of the North Atlantic's hydrography, distinguishable in intermediate water depths by its high salinity and warm temperatures. Its spreading eastward across the Atlantic leads to accumulation of salt and heat in the North Atlantic's gyres and it has been implicated in pre-conditioning the North Atlantic ocean for the formation of North Atlantic Deep Water and thus could be a player in climate change beyond the Mediterranean region. Recent paleo-studies have shown that there is extremely high variability in the intensity of MOW on centennial and millennial timescales. In order to better understand changes in the contribution of MOW to the deep Atlantic and possible linkages with the abrupt climate changes during the last glacial, we are generating new high-resolution benthic foraminiferal Mg/Ca, Ba/Ca and oxygen isotope data from Gulf of Cadiz site MD99-2339 (35.883N, 7.528W; 1170 m water depth). This site is currently bathed in the lower core of Mediterranean Outflow. Our initial study focuses on the time period spanning 13,000 to 48,000 years ago. Grain size data from core MD99-2339 indicate systematic fluctuations in the intensity of MOW correlated with the well documented millennial-scale oscillations of the last glacial, with an increased intensity of MOW during cold periods such as the late phase of H1 and the older Dryas. Our preliminary benthic Mg/Ca data suggest that the increased MOW was generally associated with warmer temperatures in the lower core of MOW, with temperature oscillations of nearly 5C in the few thousand years surrounding H1. There is a strong correlation between bottom water temperatures at this site and SSTs derived from foraminiferal transfer functions. With additional data, we hope to use systematic variations observed in the benthic Ba/Ca data to sort out the relative contribution of Mediterranean Water and entrained North Atlantic Central Water in MOW. In combination with the benthic oxygen isotope data, Mg/Ca data will help to isolate salinity changes that will be important to identifying the mechanisms causing MOW variability.
DE: 4870 Stable isotopes
DE: 4875 Trace elements
DE: 4267 Paleoceanography
DE: 1635 Oceans (4203)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2004 AGU Fall Meeting