Abiotic Pyrite Formation Produces a Large Fe Isotope Fractionation

Romain Guilbaud; Ian B. Butler; Rob M. Ellam

doi:10.1126/science.1202924

Abiotic Pyrite Formation Produces a Large Fe Isotope Fractionation

Romain Guilbaud, Ian B. Butler, Rob M. Ellam

School of Geosciences

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Abstract / Description of output

The iron isotope composition of sedimentary pyrite has been proposed as a potential proxy to trace microbial metabolism and the redox evolution of the oceans. We demonstrate that Fe isotope fractionation accompanies abiotic pyrite formation in the absence of Fe(II) redox change. Combined fractionation factors between Fe(II)(aq), mackinawite, and pyrite permit the generation of pyrite with Fe isotope signatures that nearly encapsulate the full range of sedimentary delta Fe-56(pyrite) recorded in Archean to modern sediments. We propose that Archean negative Fe isotope excursions reflect partial Fe(II)(aq) utilization during abiotic pyrite formation rather than microbial dissimilatory Fe(III) reduction. Late Proterozoic to modern sediments may reflect greater Fe(II)(aq) utilization and variations in source composition.

Original language	English
Pages (from-to)	1548-1551
Number of pages	4
Journal	Science
Volume	332
Issue number	6037
DOIs	https://doi.org/10.1126/science.1202924
Publication status	Published - 24 Jun 2011

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title = "Abiotic Pyrite Formation Produces a Large Fe Isotope Fractionation",

abstract = "The iron isotope composition of sedimentary pyrite has been proposed as a potential proxy to trace microbial metabolism and the redox evolution of the oceans. We demonstrate that Fe isotope fractionation accompanies abiotic pyrite formation in the absence of Fe(II) redox change. Combined fractionation factors between Fe(II)(aq), mackinawite, and pyrite permit the generation of pyrite with Fe isotope signatures that nearly encapsulate the full range of sedimentary delta Fe-56(pyrite) recorded in Archean to modern sediments. We propose that Archean negative Fe isotope excursions reflect partial Fe(II)(aq) utilization during abiotic pyrite formation rather than microbial dissimilatory Fe(III) reduction. Late Proterozoic to modern sediments may reflect greater Fe(II)(aq) utilization and variations in source composition.",

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AU - Ellam, Rob M.

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AB - The iron isotope composition of sedimentary pyrite has been proposed as a potential proxy to trace microbial metabolism and the redox evolution of the oceans. We demonstrate that Fe isotope fractionation accompanies abiotic pyrite formation in the absence of Fe(II) redox change. Combined fractionation factors between Fe(II)(aq), mackinawite, and pyrite permit the generation of pyrite with Fe isotope signatures that nearly encapsulate the full range of sedimentary delta Fe-56(pyrite) recorded in Archean to modern sediments. We propose that Archean negative Fe isotope excursions reflect partial Fe(II)(aq) utilization during abiotic pyrite formation rather than microbial dissimilatory Fe(III) reduction. Late Proterozoic to modern sediments may reflect greater Fe(II)(aq) utilization and variations in source composition.

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Abiotic Pyrite Formation Produces a Large Fe Isotope Fractionation

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Anoxic transition metal isotope geochemistry

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Abiotic Pyrite Formation Produces a Large Fe Isotope Fractionation

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Anoxic transition metal isotope geochemistry

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