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Hydrothermal scavenging of ^(230)Th on the Southern East Pacific Rise during the last deglaciation

Lund, David C. and Pavia, Frank J. and Seeley, Emily I. and McCart, Sarah E. and Rafter, Patrick A. and Farley, Kenneth A. and Asimow, Paul D. and Anderson, Robert F. (2019) Hydrothermal scavenging of ^(230)Th on the Southern East Pacific Rise during the last deglaciation. Earth and Planetary Science Letters, 510 . pp. 64-72. ISSN 0012-821X. https://resolver.caltech.edu/CaltechAUTHORS:20190123-072432500

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Abstract

Thorium-230 (^(230)Th) is a fundamental tool for estimating sediment fluxes in the open ocean. Because ^(230)Th is rapidly scavenged by particles falling through the water column, the flux of ^(230)Th to underlying sediments is typically equal to its water column production rate. However, recent surveys suggest hydrothermal plumes are unusually efficient scavengers of ^(230)Th. Here we show that hydrothermal scavenging on the Southern East Pacific Rise (SEPR) resulted in ^(230)Th fluxes several times higher than the water column production rate during the last deglaciation. Elevated fluxes likely require diffusive transport of dissolved ^(230)Th from the ridge flanks towards the ridge crest. Depending on the length-scale of ^(230)Th transport, the resulting deficits in ^(230)Th may yield overestimates of sediment flux to ridge flank sediments. We also show that Fe fluxes at 19°S on the SEPR lag those at 11°S and 6°S by several thousand years, inconsistent with a signal driven by changes in deep water pH and oxygen levels. Instead, variable hydrothermal activity is the simplest explanation of the observed signals in the Pacific, Indian, and Atlantic basins.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1016/j.epsl.2018.12.037DOIArticle
ORCID:
AuthorORCID
Lund, David C.0000-0002-4847-2889
Pavia, Frank J.0000-0003-3627-0179
Farley, Kenneth A.0000-0002-7846-7546
Asimow, Paul D.0000-0001-6025-8925
Anderson, Robert F.0000-0002-8472-2494
Alternate Title:Hydrothermal scavenging of 230Th on the Southern East Pacific Rise during the last deglaciation
Additional Information:© 2019 Elsevier B.V. Received 28 August 2018, Revised 23 December 2018, Accepted 28 December 2018, Available online 18 January 2019. DCL, EIS, and SM were supported by NSF award OCE-1558641 and the UCONN Research Excellence Program. We are grateful to David Cady at UCONN for assistance with ICP-MS analyses, Jean Lynch-Stieglitz at Georgia Tech for assistance with stable isotope analyses, and Martin Fleisher at LDEO for assistance with ^(230)Th and ^(231)Pa analyses. We are also indebted to the Oregon State University Core Repository for the curation of core OC73-3-20. The OSU Repository is supported by NSF award OCE-1558679. PDA was supported by NSF awards OCE-1558372 and EAR-1551433. FJP was supported by an NSF-GRFP(DGE-16-44869). All data needed to evaluate the conclusions in the paper are present in the paper and/or the Supplementary Materials.
Funders:
Funding AgencyGrant Number
NSFOCE-1558641
University of ConnecticutUNSPECIFIED
NSFOCE-1558679
NSFOCE-1558372
NSFEAR-1551433
NSF Graduate Research FellowshipDGE-16-44869
Subject Keywords:230-Thorium; hydrothermal scavenging; glacial–interglacial; East Pacific Rise; 231-Protactinium
Record Number:CaltechAUTHORS:20190123-072432500
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20190123-072432500
Official Citation:David C. Lund, Frank J. Pavia, Emily I. Seeley, Sarah E. McCart, Patrick A. Rafter, Kenneth A. Farley, Paul D. Asimow, Robert F. Anderson, Hydrothermal scavenging of 230Th on the Southern East Pacific Rise during the last deglaciation, Earth and Planetary Science Letters, Volume 510, 2019, Pages 64-72, ISSN 0012-821X, https://doi.org/10.1016/j.epsl.2018.12.037. (http://www.sciencedirect.com/science/article/pii/S0012821X1930007X)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:92406
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:23 Jan 2019 18:38
Last Modified:03 Oct 2019 20:44

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