Triple iron isotope constraints on the role of ocean iron sinks in early atmospheric oxygenation

Andy W. Heard, Nicolas Dauphas, Romain Guilbaud, Olivier J. Rouxel, Ian B. Butler, Nicole X. Nie, Andrey Bekker

Research output: Contribution to journalArticlepeer-review

21 Citations (Scopus)

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.

Original languageEnglish
Article numberaaz8821
JournalScience
Volume370
Issue number6515
DOIs
Publication statusPublished - 23 Oct 2020

ASJC Scopus subject areas

  • Multidisciplinary

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