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

• Published in: Paleoceanography
• Main Authors: Fagel, Nathalie, Hillaire-Marcel, Claude, Humblet, Marc, Brasseur, Robert, Weis, D., Stevenson, Ross
• Other Authors: Geotop, UQAM, Canada
• Format: Article in Journal/Newspaper
• Language: English
• Published: Amer Geophysical Union 2004
• Subjects: clay mineral; sedimentary mixings; deep circulation; Nd and Pb isotopes; North Atlantic Ocean; Labrador Sea; Physical; chemical; mathematical & earth Sciences; Earth sciences & physical geography; Physique; chimie; mathématiques & sciences de la terre; Sciences de la terre & géographie physique; Denmark Strait; Greenland; North Atlantic Deep Water; North Atlantic; Northeast Atlantic
• Online Access: https://orbi.uliege.be/handle/2268/6217; https://orbi.uliege.be/bitstream/2268/6217/1/NF%20Nd-Pb%202227%20PA%202003.pdf; https://doi.org/10.1029/2003PA000993

peer reviewed 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.