Ocean mixing and ice-sheet control of seawater ²³⁴U/²³⁸U during the last deglaciation

Seawater ²³⁴U/²³⁸U provides global-scale information on continental weathering and is vital for marine U-series geochronology. Previous evidence supports an increase in ²³⁴U/²³⁸U since the last glacial, but the timing and amplitude of its variability was poorly constrained. Here we report two seawat...

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Bibliographic Details
Published in:Science
Main Authors: Chen, T, Robinson, LF, Beasley, MP, Claxton, LM, Andersen, MB, Gregoire, LJ, Wadham, J, Fornari, DJ, Harpp, KS
Format: Article in Journal/Newspaper
Language:English
Published: American Association for the Advancement of Science 2016
Subjects:
Pacific
Ice Sheet
Online Access:https://eprints.whiterose.ac.uk/105167/
https://eprints.whiterose.ac.uk/105167/10/Uranium_isotopes_revision_Sep1.pdf
https://doi.org/10.1126/science.aag1015
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Summary:Seawater ²³⁴U/²³⁸U provides global-scale information on continental weathering and is vital for marine U-series geochronology. Previous evidence supports an increase in ²³⁴U/²³⁸U since the last glacial, but the timing and amplitude of its variability was poorly constrained. Here we report two seawater ²³⁴U/²³⁸U records based on well-preserved deep-sea corals from the low latitude Atlantic and Pacific. The Atlantic ²³⁴U/²³⁸U starts to increase before major sea level rise and overshoots the modern value by 3‰ in the early deglaciation. Deglacial ²³⁴U/²³⁸U of the Pacific converges with the Atlantic after the abrupt resumption of Atlantic meridional overturning. We suggest that ocean mixing and early deglacial release of excess ²³⁴U from enhanced subglacial melt activity of the Northern Hemisphere ice sheets have driven the observed ²³⁴U/²³⁸U evolution.

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