Ocean mixing and ice-sheet control of seawater 234 U/ 238 U during the last deglaciation
Seawater 234 U/ 238 U provides global-scale information about continental weathering and is vital for marine uranium-series geochronology. Existing evidence supports an increase in 234 U/ 238 U since the last glacial period, but the timing and amplitude of its variability has been poorly constrained...
| Published in: | Science |
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| Main Authors: | , , , , , , , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
2016
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| Subjects: | |
| Online Access: | https://hdl.handle.net/1983/3c0285ed-d329-4824-a7c4-d96776259d3d https://research-information.bris.ac.uk/en/publications/3c0285ed-d329-4824-a7c4-d96776259d3d https://doi.org/10.1126/science.aag1015 https://research-information.bris.ac.uk/ws/files/86693584/Uranium_isotopes_revision_Sep1.pdf http://www.scopus.com/inward/record.url?scp=84990834284&partnerID=8YFLogxK |
| Summary: | Seawater 234 U/ 238 U provides global-scale information about continental weathering and is vital for marine uranium-series geochronology. Existing evidence supports an increase in 234 U/ 238 U since the last glacial period, but the timing and amplitude of its variability has been poorly constrained. Here we report two seawater 234 U/ 238 U records based on well-preserved deep-sea corals from the low-latitude Atlantic and Pacific Oceans. The Atlantic 234 U/ 238 U started to increase before major sea-level rise and overshot the modern value by 3 per mil during the early deglaciation. Deglacial 234 U/ 238 U in the Pacific converged with that in the Atlantic after the abrupt resumption of Atlantic meridional overturning.We suggest that ocean mixing and early deglacial release of excess 234 U from enhanced subglacial melting of the Northern Hemisphere ice sheets have driven the observed 234 U/ 238 U evolution. |
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