Article abstract
Nature Geoscience 1, 68 - 72 (2008)
Published online: 2 December 2007 | doi:10.1038/ngeo.2007.5
Subject Category: Palaeoclimate and palaeoceanography
Influence of brine formation on Arctic Ocean circulation over the past 15 million years
Brian A. Haley1, Martin Frank1, Robert F. Spielhagen1,2 & Anton Eisenhauer1
Abstract
The early oceanographic history of the Arctic Ocean is important in regulating, and responding to, climatic changes. However, constraints on its oceanographic history preceding the Quaternary (the past 1.8 Myr) have become available only recently, because of the difficulties associated with obtaining continuous sediment records in such a hostile setting. Here, we use the neodymium isotope compositions of two sediment cores recovered near the North Pole to reconstruct over the past 
15 Myr the sources contributing to Arctic Intermediate Water, a water mass found today at depths of 200 to 1,500 m. We interpret high neodymium ratios for the period between 15 and 2 Myr ago, and for the glacial periods thereafter, as indicative of weathering input from the Siberian Putoranan basalts into the Arctic Ocean. Arctic Intermediate Water was then derived from brine formation in the Eurasian shelf regions, with only a limited contribution of intermediate water from the North Atlantic. In contrast, the modern circulation pattern, with relatively high contributions of North Atlantic Intermediate Water and negligible input from brine formation, exhibits low neodymium isotope ratios and is typical for the interglacial periods of the past 2 Myr. We suggest that changes in climatic conditions and the tectonic setting were responsible for switches between these two modes.
- IFM-GEOMAR, Leibniz Institute for Marine Sciences, Wischhofstrasse 1-3, 24148 Kiel, Germany
- Academy of Sciences, Humanities and Literature, 55131 Mainz, Germany
Correspondence to: Brian A. Haley1 e-mail: bhaley@ifm-geomar.de
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