Article (Scientific journals)
Holocene evolution of deep circulation in the northern North Atlantic traced by Sm, Nd and Pb isotopes and bulk sediment mineralogy
Fagel, Nathalie; Mattielli, Nadine
2011In Paleoceanography, 26, p. 4220, doi:10.1029/2011PA002168, 2011
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Keywords :
Radiogenic isotope geochemistry; Marine sediments; Geochemical tracers; Atlantic Ocean; deep oceanic circulation
Abstract :
[en] Bulk mineralogy, Sm, Nd and Pb elemental and isotopic compositions of the clay-size fraction of Holocene sediments were analysed in 3 deep North Atlantic cores to trace the particle provenance. The aims of the present paper are to identify the origin of the particles driven by deep currents and to reconstruct deep circulation changes over the Holocene in the North Atlantic. The three cores are retrieved in fracture zones; two of them are located in the Island Basin along the gyre of North Atlantic Deep Water, and the third core is located off the present deep circulation gyre in the Labrador Sea. Whereas sedimentary supplies in the Labrador Sea were constantly derived from proximal sources, the geochemical mixing trends in the Iceland Basin samples indicate pronounced changes in the relative contribution of continental margin inputs over the past 6 kyr. Supplies from Western European margin that sharply increased at 6 kyr were progressively diluted by a larger contribution of Scandinavian margins over the last 3 kyr. Changes in composition of the particles imply significant reorganisation of paleocirculation of the deep North Atlantic components in the Eastern basins: mainly reorganisations for both Iceland-Scotland Overflow Water (ISOW) and Norwegian Sea Overflow Water (NSOW). Moreover the unusual Bulk mineralogy, Sm, Nd and Pb elemental and isotopic compositions of the clay-size fraction of Holocene sediments were analysed in 3 deep North Atlantic cores to trace the particle provenance. The aims of the present paper are to identify the origin of the particles driven by deep currents and to reconstruct deep circulation changes over the Holocene in the North Atlantic. The three cores are retrieved in fracture zones; two of them are located in the Island Basin along the gyre of North Atlantic Deep Water, and the third core is located off the present deep circulation gyre in the Labrador Sea. Whereas sedimentary supplies in the Labrador Sea were constantly derived from proximal sources, the geochemical mixing trends in the Iceland Basin samples indicate pronounced changes in the relative contribution of continental margin inputs over the past 6 kyr. Supplies from western European margin that sharply increased at 6 kyr were progressively diluted by a larger contribution of Scandinavian margins over the last 3 kyr. Changes in composition of the particles imply significant reorganisation of paleocirculation of the deep North Atlantic components in the eastern basins: mainly reorganisations for both Iceland-Scotland Overflow Water (ISOW) and Norwegian Sea Overflow Water (NSOW). Moreover the unusual Pb isotopic composition of the oldest sediments from the southern Iceland Basin indicates that distal supplies from Greenland margin were driven into the Iceland Basin, supporting a deep connection between Labrador Sea and Iceland Basin through the Charlie Gibbs Fracture Zone prior the Holocene Transition period.
Research center :
Geosciences, Mare
Disciplines :
Earth sciences & physical geography
Author, co-author :
Fagel, Nathalie  ;  Université de Liège - ULiège > Département de géologie > Argiles, géochimie et environnements sédimentaires
Mattielli, Nadine ;  Université de Bruxelles > DSTE
Language :
English
Title :
Holocene evolution of deep circulation in the northern North Atlantic traced by Sm, Nd and Pb isotopes and bulk sediment mineralogy
Publication date :
2011
Journal title :
Paleoceanography
ISSN :
0883-8305
eISSN :
1944-9186
Publisher :
American Geophysical Union, Washington, United States - District of Columbia
Volume :
26
Pages :
PA4220, doi:10.1029/2011PA002168, 2011
Peer reviewed :
Peer Reviewed verified by ORBi
Funders :
F.R.S.-FNRS - Fonds de la Recherche Scientifique [BE]
Available on ORBi :
since 10 November 2011

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