Boundary scavenging at the East Atlantic margin does not negate use of Pa-231/Th-230 to trace Atlantic overturning
The231Pa/230Th method is a promising tool to reconstruct Ocean circulation over the past Glacial-Interglacial cycle. However, marine particle flux may constrain the applicability of this ratio as a direct quantitative proxy for the strength of Atlantic Meridional Overturning Circulation (AMOC) by in...
Published in: | Earth and Planetary Science Letters |
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Main Authors: | , , , , , |
Format: | Article in Journal/Newspaper |
Language: | unknown |
Published: |
Elsevier
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Subjects: | |
Online Access: | http://hdl.handle.net/1885/72312 https://doi.org/10.1016/j.epsl.2012.04.005 https://openresearch-repository.anu.edu.au/bitstream/1885/72312/5/EarthScavenging.pdf.jpg https://openresearch-repository.anu.edu.au/bitstream/1885/72312/7/01_Lippold_Boundary_scavenging_at_the_2012.pdf.jpg |
Summary: | The231Pa/230Th method is a promising tool to reconstruct Ocean circulation over the past Glacial-Interglacial cycle. However, marine particle flux may constrain the applicability of this ratio as a direct quantitative proxy for the strength of Atlantic Meridional Overturning Circulation (AMOC) by influencing the fractionation between the in situ produced231Pa and230Th in ocean water. Here we present231Pa/230Th down-core profiles from high particle flux areas off Namibia and Senegal covering the past ~35ka. The231Pa/230Th profiles at these sites show very different responses to temporal variations of particle fluxes and to changes in water masses. Our results show that sedimentary231Pa/230Th in the Eastern Atlantic margin is linked to particle flux, but controlled primarily by the mode of the AMOC. Our data suggest that during the past ~30ka the high productivity Eastern margin was not capable of importing and storing significant amounts of231Pa from the open Ocean. Consequently, the applicability of the231Pa/230Th proxy to reconstruct past ocean circulation is not hampered by this potentially additional231Pa sink. |
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