Nd and Pb isotope signatures of the clay-size fraction of Labrador Sea sediments during the Holocene: Implications for the inception of the modern deep circulation pattern
|Author(s)||Fagel N1, Hillaire-Marcel C2, Humblet M1, Brasseur R1, Weis D3, Stevenson R2|
|Affiliation(s)||1 : Univ Liege, Dept Geol & Oceanog, UR Clay & Paleoclimate & Mare, B-4000 Liege, Belgium.
2 : Univ Quebec, Geotop, Ctr Rech Geochim & Geodynam, Montreal, PQ H3C 3P8, Canada.
3 : Univ British Columbia, Pacific Ctr Isotop & Geochem Res, Vancouver, BC V6T 1Z4, Canada.
|Source||Paleoceanography (0883-8305) (Amer Geophysical Union), 2004-07 , Vol. 19 , N. PA3002 , P. 1-16|
|WOS© Times Cited||52|
|Keyword(s)||clay-size fraction, sedimentary mixings, deep circulation, Nd and Pb isotopes, North Atlantic, Labrador Sea|
|Abstract||Nd and Pb isotopes were measured on the fine fraction of one sediment core drilled off southern Greenland. This work aims to reconstruct the evolution of deep circulation patterns in the North Atlantic during the Holocene on the basis of sediment supply variations. For the last 12 kyr, three sources have contributed to the sediment mixture: the North American Shield, the Pan-African and Variscan crusts, and the Mid-Atlantic Ridge. Clay isotope signatures indicate two mixtures of sediment sources. The first mixture (12.2-6.5 ka) is composed of material derived from the North American shield and from a "young'' crustal source. From 6.5 ka onward the mixture is characterized by a young crustal component and by a volcanic component characteristic of the Mid-Atlantic Ridge. Since the significant decrease in proximal deglacial supplies, the evolution of the relative contributions of the sediment sources suggests major changes in the relative contributions of the deep water masses carried by the Western Boundary Undercurrent over the past 8.4 kyr. The progressive intensification of the Western Boundary Undercurrent was initially associated mainly with the transport of the Northeast Atlantic Deep Water mass until 6.5 ka and with the Denmark Strait Overflow Water thereafter. The establishment of the modern circulation at 3 ka suggests a reduced influence of the Denmark Strait Overflow Water, synchronous with the full appearance of the Labrador Seawater mass. Our isotopic data set emphasizes several changes in the relative contribution of the two major components of North Atlantic Deep Water throughout the Holocene.|