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Position of the Polar Front along the western Iberian margin during key cold episodes of the last 45 ka
EPOC, UMR 5805, Université Bordeaux 1, Avenue des Facultés, F-33405 Talence, France
Departamento de Geologia Marinha, LNEG, Estrada da Portela, 2721-866 Zambujal, Portugal
Departamento de Geologia Marinha, LNEG, Estrada da Portela, 2721-866 Zambujal, Portugal
Leibniz Institute of Marine Sciences at University of Kiel (IFM-GEOMAR), Wischhofstrasse 1-3, D-24148 Kiel, Germany
Departamento de Geologia Marinha, LNEG, Estrada da Portela, 2721-866 Zambujal, Portugal
EPOC, UMR 5805, Université Bordeaux 1, Avenue des Facultés, F-33405 Talence, France
EPOC, UMR 5805, Université Bordeaux 1, Avenue des Facultés, F-33405 Talence, France
EPOC, UMR 5805, Université Bordeaux 1, Avenue des Facultés, F-33405 Talence, France
Departamento de Geologia Marinha, LNEG, Estrada da Portela, 2721-866 Zambujal, Portugal
EPOC, UMR 5805, Université Bordeaux 1, Avenue des Facultés, F-33405 Talence, France
EPOC, UMR 5805, Université Bordeaux 1, Avenue des Facultés, F-33405 Talence, France
Departament d'Estratigrafia, Paleontologia i Geociències Marines, Facultat de Geologia, University of Barcelona, Diagonal Sud, c/Martí Franques s/n, E-08028 Barcelona, Spain
This paper documents the migration of the Polar Front (PF) over the Iberian margin during some of the cold climatic extremes of the last 45 ka. It is based on a compilation of robust and coherent paleohydrological proxies obtained from eleven cores distributed between 36 and 42°N. Planktonic δ 18O (Globigerina bulloides), ice-rafted detritus concentrations, and the relative abundance of the polar foraminifera Neogloboquadrina pachyderma sinistral were used to track the PF position. These three data sets, compared from core to core, show a consistent evolution of the sea surface paleohydrology along the Iberian margin over the last 45 ka. We focused on five time slices representative of cold periods under distinct paleoenvironmental forcings: the 8.2 ka event and the Younger Dryas (two recent cold events occurring within high values of summer insolation), Heinrich events 1 and 4 (reflecting major episodes of massive iceberg discharges into the North Atlantic), and the Last Glacial Maximum (typifying the highest ice volume accumulated in the Northern Hemisphere). For each event, we generated schematic maps mirroring past sea surface hydrological conditions. The maps revealed that the Polar Front presence along the Iberian margin was restricted to Heinrich events. The sea surface conditions during the Last Glacial Maximum were close to those at present day, except for the northern sites which briefly experienced subarctic conditions.
Received 26 January 2009; accepted 8 May 2009; published 1 July 2009.
Citation: (2009), Position of the Polar Front along the western Iberian margin during key cold episodes of the last 45 ka, Geochem. Geophys. Geosyst., 10, Q07U05, doi:10.1029/2009GC002398.
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