Triple iron isotope constraints on the role of ocean iron sinks in early atmospheric oxygenation
Heard, A.W.; Dauphas, N.; Guilbaud, R.; Rouxel, O.J.; Butler, I.B.; Nie, N.X.; Bekker, A. (2020). Triple iron isotope constraints on the role of ocean iron sinks in early atmospheric oxygenation. Science (Wash.) 370(6515): 446-449. https://dx.doi.org/10.1126/science.aaz8821
In: Science (Washington). American Association for the Advancement of Science: New York, N.Y. ISSN 0036-8075; e-ISSN 1095-9203, more
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| Authors | | Top |
- Heard, A.W.
- Dauphas, N.
- Guilbaud, R.
- Rouxel, O.J.
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- Butler, I.B.
- Nie, N.X.
- Bekker, A.
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| Abstract |
The role that iron played in the oxygenation of Earth’s surface is equivocal. Iron could have consumed molecular oxygen when Fe3+-oxyhydroxides formed in the oceans, or it could have promoted atmospheric oxidation by means of pyrite burial. Through high-precision iron isotopic measurements of Archean-Paleoproterozoic sediments and laboratory grown pyrites, we show that the triple iron isotopic composition of Neoarchean-Paleoproterozoic pyrites requires both extensive marine iron oxidation and sulfide-limited pyritization. Using an isotopic fractionation model informed by these data, we constrain the relative sizes of sedimentary Fe3+-oxyhydroxide and pyrite sinks for Neoarchean marine iron. We show that pyrite burial could have resulted in molecular oxygen export exceeding local Fe2+ oxidation sinks, thereby contributing to early episodes of transient oxygenation of Archean surface environments. |
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