Reconstruction of oceanic circulation using mineralogical and isotopical (Nd/Pb) signatures of deep sea sediments: the case study of the northern North Atlantic and some perspectives for the Arctic

• Main Author: Fagel, N.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2009
• Subjects: Arctic; Greenland; Denmark Strait; Labrador Sea; North Atlantic Deep Water; North Atlantic; North East Atlantic
• Online Access: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=239361

This work aims to reconstruct the evolution of deep ocean circulation patterns in the North Atlantic during the last 10-100 kyr using abiotic proxies. Nd and Pb isotopic ratios have been measured on the clay-sized fraction of two sediment cores drilled in the Labrador Sea off southern Greenland (MD99-2227, ODP646). At present this site is under the influence of the Western Boundary Undercurrent that drives the water masses involved in the fort-nation of the North Atlantic Deep Water. Based on an identification of regional sources areas sedimentary isotopic signatures allow to determine the origin of the particles driven by the North Atlantic deep Currents: any change in the sediment supplies reflects a relative change in the contribution of the deep water masses. Our isotopic dataset emphasizes several main changes in the relative contribution of the two major components of North Atlantic Deep Water, i.e. the North East Atlantic Deep water (NEADW) and the Denmark Strait Overflow Water (DSOW) throughout the last 12 kyr, and especially during the Late Holocene. The inception of the modem deep circulation seems to be quite recent, occurring during the last 3 kyr. Over glacial/interglacial time-scale deep current variability is less pronounced and/or partly masked by variable proximal supplies. Labrador Sea results emphasize that the application of mineralogical and isotopical tools on sediments allow to monitor variability in sedimentary supplies driven by deep currents. This indirect approach is further promising to identify deep currents pathways and reconstruct past circulation.