Bulk and grain-scale minor sulfur isotope data reveal complexities in the dynamics of Earth’s oxygenation
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pnas.2025606119.pdf
Description
Published version
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2.17 MB
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Author(s)
Izon, Gareth
Luo, Genming
Uveges, Benjamin T
Beukes, Nicolas
Kitajima, Kouki
Ono, Shuhei
Valley, John W
Ma, Xingyu
Summons, Roger E
Date Issued
2022
Journal
Proceedings of the National Academy of Sciences of the United States of America
Publisher
Proceedings of the National Academy of Sciences
Citation
Izon, Gareth, Luo, Genming, Uveges, Benjamin T, Beukes, Nicolas, Kitajima, Kouki et al. 2022. "Bulk and grain-scale minor sulfur isotope data reveal complexities in the dynamics of Earth’s oxygenation." Proceedings of the National Academy of Sciences of the United States of America, 119 (13).
Version
Final published version
Abstract
Significance
The permanent disappearance of mass-independent sulfur isotope fractionation (S-MIF) from the sedimentary record has become a widely accepted proxy for atmospheric oxygenation. This framework, however, neglects inheritance from oxidative weathering of pre-existing S-MIF–bearing sedimentary sulfide minerals (i.e., crustal memory), which has recently been invoked to explain apparent discrepancies within the sulfur isotope record. Herein, we demonstrate that such a crustal memory effect does not confound the Carletonville S-isotope record; rather, the pronounced Δ 33 S values identified within the Rooihoogte Formation represent the youngest known unequivocal oxygen-free photochemical products. Previously observed 33 S-enrichments within the succeeding Timeball Hill Formation, however, contrasts with our record, revealing kilometer-scale heterogeneities that highlight significant uncertainties in our understanding of the dynamics of Earth’s oxygenation.
The permanent disappearance of mass-independent sulfur isotope fractionation (S-MIF) from the sedimentary record has become a widely accepted proxy for atmospheric oxygenation. This framework, however, neglects inheritance from oxidative weathering of pre-existing S-MIF–bearing sedimentary sulfide minerals (i.e., crustal memory), which has recently been invoked to explain apparent discrepancies within the sulfur isotope record. Herein, we demonstrate that such a crustal memory effect does not confound the Carletonville S-isotope record; rather, the pronounced Δ 33 S values identified within the Rooihoogte Formation represent the youngest known unequivocal oxygen-free photochemical products. Previously observed 33 S-enrichments within the succeeding Timeball Hill Formation, however, contrasts with our record, revealing kilometer-scale heterogeneities that highlight significant uncertainties in our understanding of the dynamics of Earth’s oxygenation.
MIT Department
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
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Creative Commons Attribution-NonCommercial-NoDerivs License
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DOI of Published Version
https://doi.org/10.1073/PNAS.2025606119
