The timing of deglacial circulation changes in the Atlantic

Type Article
Date 2011-08
Language English
Author(s) Waelbroeck C.1, Skinner L. C.2, Labeyrie L.1, Duplessy J. -C.1, Michel E.1, Vazquez Riveiros Natalia1, Gherardi J. M.1, 3, Dewilde F.1
Affiliation(s) 1 : UVSQ, LSCE IPSL, Lab CNRS, CEA,Domaine CNRS, F-91198 Gif Sur Yvette, France.
2 : Univ Cambridge, Godwin Lab Paleoclimate Res, Cambridge CB2 3EQ, England.
3 : Bjerknes Ctr Climate Res, N-5007 Bergen, Norway.
Source Paleoceanography (0883-8305) (Amer Geophysical Union), 2011-08 , Vol. 26 , N. PA3213 , P. 1-10
DOI 10.1029/2010PA002007
WOS© Times Cited 68
Keyword(s) Atlantic Ocean, benthic oxygen isotope, last deglaciation, ocean circulation
Abstract Well-dated benthic foraminifer oxygen isotopic records (delta O-18) from different water depths and locations within the Atlantic Ocean exhibit distinct patterns and significant differences in timing over the last deglaciation. This has two implications: on the one hand, it confirms that benthic delta O-18 cannot be used as a global correlation tool with millennial-scale precision, but on the other hand, the combination of benthic isotopic records with independent dating provides a wealth of information on past circulation changes. Comparing new South Atlantic benthic isotopic data with published benthic isotopic records, we show that (1) circulation changes first affected benthic delta O-18 in the 1000-2200 m range, with marked decreases in benthic delta O-18 taking place at similar to 17.5 cal. kyr B.P. (ka) due to the southward propagation of brine waters generated in the Nordic Seas during Heinrich Stadial 1 (HS1) cold period; (2) the arrival of delta O-18-depleted deglacial meltwater took place later at deeper North Atlantic sites; (3) hydrographic changes recorded in North Atlantic cores below 3000 m during HS1 do not correspond to simple alternations between northern-and southern-sourced water but likely reflect instead the incursion of brine-generated deep water of northern as well as southern origin; and (4) South Atlantic waters at similar to 44 degrees S and similar to 3800 m depth remained isolated from better-ventilated northern-sourced water masses until after the resumption of North Atlantic Deep Water (NADW) formation at the onset of the Bolling-Allerod, which led to the propagation of NADW into the South Atlantic.
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