HR: 0800h
AN: PP41B-0653    [Abstracts]
TI: Surface Water Variability During MIS 10-13 on the Portuguese Margin
AU: * Rodrigues, T A
EM: teresa.rodrigues@ineti.pt
AF: INETI- Portugal, Estrada da Portela- Zambujal, Alfragide, 2721-866 Portugal
AU: * Rodrigues, T A
EM: teresa.rodrigues@ineti.pt
AF: IIQAb-CSIC Barcelona, C/ Jordy Girona 18, BArcelona, 08034 Spain
AU: Voelker, A B
EM: antje.voelker@ineti.pt
AF: INETI- Portugal, Estrada da Portela- Zambujal, Alfragide, 2721-866 Portugal
AU: Abrantes, F F
EM: fatima.abrantes
AF: INETI- Portugal, Estrada da Portela- Zambujal, Alfragide, 2721-866 Portugal
AU: Grimalt, J O
EM:
AF: IIQAb-CSIC Barcelona, C/ Jordy Girona 18, BArcelona, 08034 Spain
AU: de Abreu, L
EM:
AF: INETI- Portugal, Estrada da Portela- Zambujal, Alfragide, 2721-866 Portugal
AU: Lebreiro, S
EM:
AF: INETI- Portugal, Estrada da Portela- Zambujal, Alfragide, 2721-866 Portugal
AB: One of the important discoveries from the EPICA Dome C (EDC) ice core in Antarctica is the change from cooler, but longer lasting Interglacials prior to Marine Isotope Stage (MIS) 11 to warmer, but shorter Interglacial peaks after MIS 11. In order to better understand the climatic conditions during this pattern change we are studying the interval from MIS 10 in core MD03-2699 from the western Portuguese Margin. Total alkenone concentrations are related to Haptophyte productivity in the overlying surface waters. In the study area Haptophyte. (coccolithophores) are the dominant phytoplankter during winter months (Abrantes & Moita,1999). Total alkenones' concentration together with XRF-Calciun record reveal changes in paleo-productivity; plant derived biomarkers those in the terrigenous input. Alkenone-based temperatures reach up to 19°C in MIS 11, in agreement with planktonic foraminifera assemblage based SST estimates in core MD01-2443, which is located about 1 degree to the south. SST during MIS 11 and 13 show similar values in absolute terms, but MIS 11's peak warmth is nearly 1°C higher. Thus SST record of core MD03-2699 differs from the EDC deltaD temperature record, where temperatures are clearly higher during MIS 11. Within MIS 12 rapid SST oscillations are in phase with both Ca variations and alkenone concentration peaks, pointing towards palaeoproductivity changes either associated with fluctuations in the water masses affecting the region and/or due to alterations in the subpolar front off Portugal during this glacial interval. Peak productivity during Termination V/ beginning of MIS 11 coincides with coldest SST values, pointing to increased upwelling activity during that period. In MIS 13 the alkenone concentration pattern shows a close similarity to the EDC δD record, with two maxima at 470 and 500 kyrs, which could be indicative palaeoproductivity changes in this upwelling zone might be linked to the same, yet unknown forcing mechanism(s) that drive the Antarctic variations.
DE: 3344 Paleoclimatology (0473, 4900)
DE: 4900 PALEOCEANOGRAPHY (0473, 3344)
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005