Holocene evolution of deep circulation in the northern North Atlantic traced by Sm, Nd and Pb isotopes and bulk sediment mineralogy

Type Article
Date 2011-12
Language English
Author(s) Fagel N.1, Mattielli N.2
Affiliation(s) 1 : Univ Liege, UR Argiles Geochim & Environm Sedimentaires, B-4000 Liege, Belgium.
2 : Univ Libre Bruxelles, Dept Sci Terre & Environm, B-1050 Brussels, Belgium.
Source Paleoceanography (0883-8305) (Amer Geophysical Union), 2011-12 , Vol. 26 , N. 4 / PA4220 , P. 1-15
DOI 10.1029/2011PA002168
WOS© Times Cited 9
Note Auxiliary material for this article contains age, bulk mineralogy and Nd and Pb isotopic data of the four studied cores: MD99-2254, HU91 -045-080TWC, HU91-045-080P (Iceland Basin) and HU91-045-091P (Labrador Sea). : http://onlinelibrary.wiley.com/doi/10.1029/2011PA002168/suppinfo
Abstract Bulk mineralogy, Sm, Nd and Pb elemental and isotopic compositions of the clay-size fraction of Holocene sediments were analyzed in three 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 reorganization of paleocirculation of the deep North Atlantic components in the eastern basins: mainly reorganizations for both Iceland-Scotland Overflow Water and Norwegian Sea Overflow Water. 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.
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