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

Autor: Heard AW; Origins Laboratory, Department of the Geophysical Sciences and Enrico Fermi Institute, The University of Chicago, Chicago, IL 60637, USA. andyheard@uchicago.edu., Dauphas N; Origins Laboratory, Department of the Geophysical Sciences and Enrico Fermi Institute, The University of Chicago, Chicago, IL 60637, USA., Guilbaud R; Géosciences Environnement Toulouse, CNRS, UMR5563, 31400 Toulouse, France., Rouxel OJ; Unité Géosciences Marines, IFREMER, Plouzané 29280, France., Butler IB; School of Geosciences, University of Edinburgh, Grant Institute, Edinburgh EH9 3JW, UK., Nie NX; Origins Laboratory, Department of the Geophysical Sciences and Enrico Fermi Institute, The University of Chicago, Chicago, IL 60637, USA.; Earth and Planets Laboratory, Carnegie Institution for Science, Washington, DC 20015, USA., Bekker A; Department of Earth and Planetary Sciences, University of California, Riverside, CA 92521, USA.; Department of Geology, University of Johannesburg, Johannesburg 2006, South Africa.
Jazyk: angličtina
Zdroj: Science (New York, N.Y.) [Science] 2020 Oct 23; Vol. 370 (6515), pp. 446-449.
DOI: 10.1126/science.aaz8821
Abstrakt: The role that iron played in the oxygenation of Earth's surface is equivocal. Iron could have consumed molecular oxygen when Fe 3+ -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 Fe 3+ -oxyhydroxide and pyrite sinks for Neoarchean marine iron. We show that pyrite burial could have resulted in molecular oxygen export exceeding local Fe 2+ oxidation sinks, thereby contributing to early episodes of transient oxygenation of Archean surface environments.
(Copyright © 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)
Databáze: MEDLINE
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