Plio-Pleistocene evolution of Arctic-Atlantic water mass exchange and erosional input in the Fram Strait

• Main Authors: Teschner, Claudia, Frank, Martin, Haley, Brian A., Knies, Jochen
• Format: Conference Object
• Language: unknown
• Published: 2011
• Subjects: Arctic; Arctic Ocean; Greenland; Yermak Plateau; Fram Strait; Yermak plateau
• Online Access: https://oceanrep.geomar.de/id/eprint/12899/; http://www.geo.uni-potsdam.de/icdp_homepage/downloads/Abstractband_M%C3%BCnster_2011a.pdf

We determined the isotopic composition of neodymium (Nd) and lead (Pb) of past seawater to reconstruct water mass exchange and erosional input between the Arctic Ocean and the Norwegian-Greenland Seas over the past 5 Myr. For this purpose, sediments of ODP site 911 (leg 151) located at 900 m water depth on the Yermak Plateau in the Fram Strait were used. The paleo-seawater variability of Nd and Pb isotopes was extracted from the sea water-derived metal oxide coatings on the sediment particles following the leaching method of Gutjahr et al. (2007). All radiogenic isotope data were acquired by Multi-Collector (MC) ICP-MS. The site 911 stratigraphy of Knies et al. (2009) was applied. Surface sediment Sr and Nd isotope data, as well as downcore Sr isotope data obtained on the same leaches are close to seawater and confirm the seawater origin of the Nd and Pb isotope signatures. The deep water Nd isotope composition extracted from site 911 was in general more radiogenic (εNd = -4.3 to -10) than present day deep water (-10.1 to -11.8) in the area of the Fram Strait (Andersson et al., 2008) and does not show a systematic long-term trend over time. In contrast, the radiogenic isotope composition of Pb evolved from 206Pb/204Pb ratios around 18.55 to more radiogenic values around 19.15 between 2 Ma and today. Over the past 5 million years the data indicate that overall mixing of water masses from the Arctic Ocean and the Norwegian-Greenland Seas have controlled the Nd isotope signatures on the Yermak Plateau. Prior to 1.7 Ma the Nd isotope signatures were somewhat less radiogenic than waters from approximately the same depth in the central Arctic Ocean (Haley et al., 2008) pointing to a greater influence of inflowing waters from the Norwegian-Greenland Seas. After 1.7 Ma intermediate waters in the central Arctic and on Yermak Plateau have varied around similar values indicating general water mass mixing conditions similar to today. In contrast, the Pb isotopic composition increased after 2.2 Ma, which resembles the Pb ...