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...

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Bibliographic Details
Published in:Earth and Planetary Science Letters
Main Authors: Lippold, Jorg, Mulitza, Stefan, Mollenhauer , Gesine, Weyer, Stefan, Heslop, David, Christl, M
Format: Article in Journal/Newspaper
Language:unknown
Published: Elsevier
Subjects:
Keywords: African margin
AMOC
Boundary scavenging
LGM
North Atlantic Deep Water
Geology
Mathematical models
Oceanography
core analysis
glacial-interglacial cycle
in situ measurement
isotopic composition
Last Glacial Maximum
meridional circulation
ocea 231Pa/ 230Th
African margin
North Atlantic
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
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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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