Late Quaternary variability of Mediterranean Outflow Water from radiogenic Nd and Pb isotopes

• Published in: Quaternary Science Reviews
• Main Authors: Stumpf, Roland, Frank, Martin, Schönfeld, Joachim, Haley, Brian A.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2010
• Subjects: North Atlantic
• Online Access: https://oceanrep.geomar.de/id/eprint/8814/; https://oceanrep.geomar.de/id/eprint/8814/1/Stumpf.pdf; https://doi.org/10.1016/j.quascirev.2010.06.021

Mediterranean Outflow Water (MOW) is characterised by higher temperatures and salinities than other ambient water masses. MOW spreads at water depths between 500 and 1500 m in the eastern North Atlantic and has been a source of salinity for the Atlantic Meridional Overturning Circulation in the North Atlantic. We used high-resolution Nd and Pb isotope records of past ambient seawater obtained from authigenic ferromanganese coatings of sediments in three gravity cores at 577, 1745 and 1974 m water depth in the Gulf of Cadiz and along the Portuguese margin complemented by a selection of surface sediments to reconstruct the extent and pathways of MOWover the past 23 000 years. The surface and downcore Nd isotope data from all water depths exhibit only a very small variability close to the present day composition of MOWbut do not reflect the present day Nd isotopic stratification of the water column as determined from a nearby open ocean hydrographic station. In contrast, the Pb isotope records show significant and systematic variations, which provide evidence for a significantly different pattern of the MOW pathways between 20 000 and 12 000 years ago compared with the subsequent period of time.