Abiotic pyrite formation produces a large Fe isotope fractionation

Guilbaud, R., Butler, I.B. and Ellam, R.M. (2011) Abiotic pyrite formation produces a large Fe isotope fractionation. Science, 332(6037), pp. 1548-1551. (doi: 10.1126/science.1202924)

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Publisher's URL: http://dx.doi.org/10.1126/science.1202924


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)<sub>aq</sub>, mackinawite, and pyrite permit the generation of pyrite with Fe isotope signatures that nearly encapsulate the full range of sedimentary δ<sup>56</sup>Fe<sub>pyrite</sub> 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)<sub>aq</sub> utilization and variations in source composition.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Ellam, Professor Rob
Authors: Guilbaud, R., Butler, I.B., and Ellam, R.M.
College/School:College of Science and Engineering > Scottish Universities Environmental Research Centre
Journal Name:Science
Publisher:American Association for the Advancement of Science
ISSN (Online):1095-9203

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