Lea, D. W.

Lebreiro, Susana

Martin, Pamela A.

Voelker, Antje H. L.

Repositório do LNEG

2008 Fall Meeting          Search ResultsCite abstracts as Author(s) (2008), Title, Eos Trans. AGU,89(53), Fall Meet. Suppl., Abstract xxxxx-xxYour query was:voelkerHR: 1340hAN: PP33C-1566TI:  Tracing  the  Influence  of  Mediterranean  Outflow  Waters  on  the  Mid-depth  PortugueseMargin Between Marine Isotope Stages 9 and 13AU: * Voelker, A HEM: avoelker@softhome.netAF: Dept. Geologia Marinha, INETI (future LNEG) Estrada da Portela, Zambujal, Alfragide, 2721-866,PortugalAU: * Voelker, A HEM: avoelker@softhome.netAF: CIMAR Associate Laboratory, Rua dos Bragas 289, Porto, 4050-123, PortugalAU: Martin, PEM: pmartin@uchicago.eduAF:  Department  of  the  Geophysical  Sciences,  The  University  of  Chicago,  5734  S.  Ellis  Avenue,Chicago, IL 60637, United StatesAU: Lea, D WEM: lea@geol.ucsb.eduAF: Dept. of Earth Science, University of California, Santa Barbara, CA 93106-963, United StatesAU: Lebreiro, SEM: susana.lebreiro@ineti.ptAF: Dept. Geologia Marinha, INETI (future LNEG) Estrada da Portela, Zambujal, Alfragide, 2721-866,PortugalAB: Calypso piston core MD03-2699 was retrieved from the Estremadura promontory north of Lisbonfrom a  water  depth  of  1895  m.  Nowadays,  this  site  is  bathed  by  Northeast  Atlantic  Deep  Water(NEADW), whose physical properties are modified by diffusive mixing with the overlying MediterraneanOutflow Water (MOW; 700-1400 m). During the last glacial maximum the MOW became denser andsettled deeper in the water column and its lower core's flow strength increased on millennial time scalesduring the Greenland stadials of the last 50 ka. In order to reconstruct deep-water variations on themid-depth Portuguese margin during the mid-Brunhes we generated benthic stable isotope and traceelement records and measured the mean grain size <63µm for the interval from 300 to 510 ka. Becauseof the strong MOW derived salinity overprint on the benthic Mg/ Ca data we currently use the westernMediterranean equation (Cacho et al., 2006) to calculate bottom water temperatures (BWT). During theMIS 10 glacial inception, BWT and grain size records reveal millennial-scale oscillation in deep-waterconditions with warmer MOW waters (8-10°C) bathing the site during stadials and NEADW (5-7°C)during interstadials. The lower MOW core was the dominant water mass throughout glacial MIS 10 and12 and NEADW during interglacial MIS 9.5 and 11.31. During MIS 13.1, on the other hand, strong MOWinfluence on the BWT is observed nearly throughout with NEADW-level BWT occurring only between493 and 497 ka. During termination IV the MOW/ NEADW boundary shifted upwards right at the onsetof the termination, but during termination V the lower MOW core settled further up in the water columnonly after 408 ka. The Cd/ Ca data indicates that the glacial and stadial MOW was enriched in nutrientseither by exporting nutrients from the Mediterranean Sea or by mixing with southern source waters.Overall, our records reveal that deep-water dynamics on the mid-depth Portuguese margin were veryvariable during the mid-Brunhes, experienced millennial-scale oscillations similar to the last glacial cycleand are driven by the density and thus settling depth of the MOW.DE: 4901 Abrupt/rapid climate change (1605)DE: 4924 Geochemical tracersDE: 4962 ThermohalineSC: Paleoceanography and Paleoclimatology [PP]MN: 2008 Fall Meeting   New Search

Tracing the influence of Mediterranean outflow waters on the Mid-depth portuguese margin between Marine Isotope Stages 9 and 13

http://repositorio.lneg.pt/bitstream/10400.9/3013/1/34748.pdf

Tracing the influence of Mediterranean outflow waters on the Mid-depth portuguese margin between Marine Isotope Stages 9 and 13

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