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Centennial- to millennial-scale ice-ocean interactions in the subpolar Northeast Atlantic 18-41 kyr ago

Hall, I.R.; Colmenero-Hidalgo, E.; Zahn, R.; Peck, Victoria L.; Hemming, S.R.. 2011 Centennial- to millennial-scale ice-ocean interactions in the subpolar Northeast Atlantic 18-41 kyr ago. Paleoceanography, 26 (2), PA2224. 18, pp. 10.1029/2010PA002084

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Abstract/Summary

In order to monitor the evolution of the British-Irish Ice Sheet (BIIS) and its influence in surface ocean structure during marine isotopic stages (MIS) 2 and 3, we have analyzed the sediments recovered in core MD04-2829CQ (Rosemary Bank, north Rockall Trough, northeast Atlantic) dated between similar to 41 and similar to 18 ka B.P. Ice-rafted debris flux and composition, (40)Ar/(39)Ar ages of individual hornblende grains, multispecies planktonic stable isotope records, planktonic foraminifera assemblage data and faunal-based sea surface temperatures (SSTs) demonstrate a close interaction between BIIS dynamics and surface ocean structure and water properties in this region. The core location lies beneath the North Atlantic Current (NAC) and is ideal for monitoring the shifts in the position of its associated oceanic fronts, as recorded by faunal changes. These data reveal a succession of BIIS-sourced iceberg calving events related to low SST, usually synchronous with dramatic changes in the composition of the planktonic foraminifera assemblage and with variations in the stable isotope records of the taxa Neogloboquadrina pachyderma (sinistral coiling) and Globigerina bulloides. The pacing of the calving events, from typically Dansgaard-Oeschger millennial timescales during late MIS 3 to multicentennial cyclicity from similar to 28 ka B.P., represents the build-up of the BIIS and its growing instability toward Heinrich Event (HE) 2 and the Last Glacial Maximum. Our data confirm the strong coupling between BIIS instabilities and the temperature and salinity of surface waters in the adjacent northeast Atlantic and demonstrate the BIIS's ability to modify the NAC on its flow toward the Nordic Seas. In contrast, subsurface water masses were less affected except during the Greenland stadials that contain HEs, when most intense water column reorganizations occurred simultaneously with the deposition of cream-colored carbonate sourced from the Laurentide Ice Sheet.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1029/2010PA002084
Programmes: BAS Programmes > Polar Science for Planet Earth (2009 - ) > Chemistry and Past Climate
ISSN: 0883-8305
NORA Subject Terms: Glaciology
Date made live: 11 Oct 2011 12:53
URI: http://nora.nerc.ac.uk/id/eprint/15272

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