South Atlantic intermediate water advances into the North-east Atlantic with reduced Atlantic meridional overturning circulation during the last glacial period

The Nd isotopic composition (epsilon Nd) of seawater and cold-water coral (CWC) samples from the Gulf of Cadiz and the Alboran Sea, at a depth of 280-827 m were investigated in order to constrain middepth water mass dynamics within the Gulf of Cadiz over the past 40 ka. epsilon Nd of glacial and Hol...

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Bibliographic Details
Published in:Geochemistry, Geophysics, Geosystems
Main Authors: Dubois-Dauphin, Quentin, Bonneau, Lucile, Colin, Christophe, Montero-Serrano, Jean-Carlos, Montagna, Paolo, Blamart, Dominique, Hebbeln, Dierk, Van Rooij, David, Pons-Branchu, Edwige, Hemsing, Freya, Wefing, Anne-Marie, Frank, Norbert
Format: Article in Journal/Newspaper
Language:English
Published: 2016
Subjects:
Earth and Environmental Sciences
neodymium isotopes
cold-water corals
Mediterranean outflow water
East Antarctic intermediate water
Mediterranean sea water
Gulf of Cadiz
DEEP-SEA CORALS
NEODYMIUM ISOTOPIC COMPOSITION
HIGH-RESOLUTION RECORD
MID-DEPTH CIRCULATION
18
000 YEARS BP
OCEAN CIRCULATION
PACIFIC-OCEAN
THERMOHALINE CIRCULATION
SURFACE-TEMPERATURE
Antarctic
Pacific
Antarc*
Iceberg*
North East Atlantic
Online Access:https://biblio.ugent.be/publication/8078729
http://hdl.handle.net/1854/LU-8078729
https://doi.org/10.1002/2016GC006281
https://biblio.ugent.be/publication/8078729/file/8078743
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Summary:The Nd isotopic composition (epsilon Nd) of seawater and cold-water coral (CWC) samples from the Gulf of Cadiz and the Alboran Sea, at a depth of 280-827 m were investigated in order to constrain middepth water mass dynamics within the Gulf of Cadiz over the past 40 ka. epsilon Nd of glacial and Holocene CWC from the Alboran Sea and the northern Gulf of Cadiz reveals relatively constant values (-8.6 to -9.0 and -9.5 to -10.4, respectively). Such values are similar to those of the surrounding present-day middepth waters from the Mediterranean Outflow Water (MOW; epsilon Nd approximate to -9.4) and Mediterranean Sea Water (MSW; epsilon Nd approximate to -9.9). In contrast, glacial epsilon Nd values for CWC collected at thermocline depth (550-827 m) in the southern Gulf of Cadiz display a higher average value (-8.90.4) compared to the present-day value (-11.70.3). This implies a higher relative contribution of water masses of Mediterranean (MSW) or South Atlantic origin (East Antarctic Intermediate Water, EAAIW). Our study has produced the first evidence of significant radiogenic epsilon Nd values (approximate to -8) at 19, 23-24, and 27 ka, which are coeval with increasing iceberg discharges and a weakening of Atlantic Meridional Overturning Circulation (AMOC). Since MOW epsilon Nd values remained stable during the last glacial period, it is suggested that these radiogenic epsilon Nd values most likely reflect an enhanced northward propagation of glacial EAAIW into the eastern Atlantic Basin.

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