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Variable Silicon Isotope Fractionation Between Authigenic Phases and Pore Fluids in Marine Sediments

Dai, Yuhao LU ; Pickering, Rebecca A. LU orcid ; Cassarino, Lucie LU orcid ; Han, Seunghee and Conley, Daniel J. LU orcid (2025) In Geophysical Research Letters 52(12).
Abstract

Formation and subsequent burial of authigenic phases have been recognized as a key process removing silicon from the ocean. However, the effect of authigenic phase formation on the isotopic mass balance of silicon in the ocean is not clear. Here, we constrain the apparent silicon isotope (δ30Si) fractionation associated with early diagenesis by measuring δ30Si signatures of pore fluids and authigenic phases in a South Atlantic sediment core. The δ30Si offsets between authigenic phases and pore fluids vary between −2.9 and −0.4‰, supporting a substantial negative δ30Si fractionation during early diagenesis. The variable apparent δ30Si fractionation covaries with the amount of... (More)

Formation and subsequent burial of authigenic phases have been recognized as a key process removing silicon from the ocean. However, the effect of authigenic phase formation on the isotopic mass balance of silicon in the ocean is not clear. Here, we constrain the apparent silicon isotope (δ30Si) fractionation associated with early diagenesis by measuring δ30Si signatures of pore fluids and authigenic phases in a South Atlantic sediment core. The δ30Si offsets between authigenic phases and pore fluids vary between −2.9 and −0.4‰, supporting a substantial negative δ30Si fractionation during early diagenesis. The variable apparent δ30Si fractionation covaries with the amount of sedimentary lithogenic materials and may be attributable to the associated kinetic effects. Overall, our data show that authigenic phases buried along with their precursor phases preferentially remove isotopically light silicon from the ocean, with implications for the isotopic mass balance of the marine silicon cycle.

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author
; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
early diagenesis, geochemistry, IODP, marine sediment, marine silicon cycle, silicon isotopes
in
Geophysical Research Letters
volume
52
issue
12
article number
e2025GL116217
publisher
American Geophysical Union (AGU)
external identifiers
  • scopus:105008438939
ISSN
0094-8276
DOI
10.1029/2025GL116217
language
English
LU publication?
yes
additional info
Publisher Copyright: © 2025. The Author(s).
id
fe885234-2022-4248-a37b-65bc9c491fc7
date added to LUP
2025-12-15 14:36:36
date last changed
2025-12-15 14:37:38
@article{fe885234-2022-4248-a37b-65bc9c491fc7,
  abstract     = {{<p>Formation and subsequent burial of authigenic phases have been recognized as a key process removing silicon from the ocean. However, the effect of authigenic phase formation on the isotopic mass balance of silicon in the ocean is not clear. Here, we constrain the apparent silicon isotope (δ<sup>30</sup>Si) fractionation associated with early diagenesis by measuring δ<sup>30</sup>Si signatures of pore fluids and authigenic phases in a South Atlantic sediment core. The δ<sup>30</sup>Si offsets between authigenic phases and pore fluids vary between −2.9 and −0.4‰, supporting a substantial negative δ<sup>30</sup>Si fractionation during early diagenesis. The variable apparent δ<sup>30</sup>Si fractionation covaries with the amount of sedimentary lithogenic materials and may be attributable to the associated kinetic effects. Overall, our data show that authigenic phases buried along with their precursor phases preferentially remove isotopically light silicon from the ocean, with implications for the isotopic mass balance of the marine silicon cycle.</p>}},
  author       = {{Dai, Yuhao and Pickering, Rebecca A. and Cassarino, Lucie and Han, Seunghee and Conley, Daniel J.}},
  issn         = {{0094-8276}},
  keywords     = {{early diagenesis; geochemistry; IODP; marine sediment; marine silicon cycle; silicon isotopes}},
  language     = {{eng}},
  month        = {{06}},
  number       = {{12}},
  publisher    = {{American Geophysical Union (AGU)}},
  series       = {{Geophysical Research Letters}},
  title        = {{Variable Silicon Isotope Fractionation Between Authigenic Phases and Pore Fluids in Marine Sediments}},
  url          = {{http://dx.doi.org/10.1029/2025GL116217}},
  doi          = {{10.1029/2025GL116217}},
  volume       = {{52}},
  year         = {{2025}},
}