Longman, J, Dunlea, AG, Böning, P et al. (6 more authors) (2023) Release of tephra-hosted iron during early diagenesis fingerprinted by iron isotopes. Earth and Planetary Science Letters, 605. 118016. ISSN 0012-821X
Abstract
The micronutrient iron (Fe) plays a fundamental role controlling primary productivity in the upper ocean, with volcanic eruptions and deposition of airborne volcanic material (termed tephra) a potential source of Fe. Here, we investigate the geochemical and Fe isotopic (δ56Fe) composition of tephra layers, sediments, and mixed tephra-sediment samples from the Integrated Ocean Drilling Program (IODP) Hole 1396C, located offshore the volcanically active island of Montserrat in the Lesser Antilles, Caribbean Sea. We find that buried tephras, which have experienced diagenesis, exhibit lighter δ56Fe (relative to standard IRMM524a) compositions (down to −0.26 ± 0.04, 2SD) than fresh tephra deposited in Montserrat (δ56Fe = 0.02 ± 0.02, 2SD). Such negative values suggest that isotopically heavier Fe has been lost from the originally deposited material. Using multivariate statistical modelling and mass balance constraints, we identify the outward Fe flux (with calculated δ56Fe of 0.21 ± 0.31, 2SD, n = 12) during nonreductive dissolution of tephra as the likely cause of the retention of these light δ56Fe compositions. Due to the widespread nature of tephra deposition, tephra diagenesis may provide an important source of isotopically heavy dissolved Fe (dFe) to the oceans. This process contrasts with more commonly considered reductive dissolution processes, which provide a source of dFe enriched in light isotopes to the oceans.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2023 Elsevier B.V. This is an author produced version of an article published in Earth and Planetary Science Letters. Uploaded in accordance with the publisher's self-archiving policy. |
Keywords: | Fe isotopes; tephra; biogeochemistry; Fe cycle; volcanism |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Earth Surface Science Institute (ESSI) (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 21 Mar 2023 12:47 |
Last Modified: | 06 Feb 2024 01:13 |
Published Version: | http://dx.doi.org/10.1016/j.epsl.2023.118016 |
Status: | Published |
Publisher: | Elsevier |
Identification Number: | 10.1016/j.epsl.2023.118016 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:197428 |
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