Pre-modern Arctic Ocean circulation from surface sediment neodymium isotopes

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Abstract

[1] We present a survey of Nd isotopes measured from authigenic phases on surface sediments from the Arctic Ocean seafloor. Comparison with published dissolved water column Nd isotope distributions suggests that εNd from sediment leachates accurately represents bottom water circulation of the Arctic Ocean, with Atlantic (~−11 εNd) and Pacific (~−5 εNd) water end-members clearly distinguishable. Nd isotopic data from the Chukchi margin show several apparent deviations from the expected pattern, which imply that this margin has been a region of sustained shelf-to-basin sediment redistribution and/or a region where deep water cascades downslope, such as through brine rejection during ice formation. These data also provide insights into a pre-anthropocene “baseline” (several thousand years) for investigating Arctic Ocean circulation in a changing climate; the data presented here are indicative that these changes may be impacting the deep as well as surface ocean.

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