Mass-independent isotope effects in Archean (2.5 to 3.8 Ga) sedimentary sulfides determined by ion microprobe analysis

S. J. Mojzsis, C. D. Coath, J. P. Greenwood, K. D. McKeegan, T. M. Harrison

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Abstract

We report sulfur isotope anomalies with Δ33S, the deviation from a mass-dependent fractionation line for the three-isotope system (34S/32S vs. 33 S/32S), ranging up to ±2‰ within individual Archean sedimentary sulfides from a variety of localities. Our measurements, which are made in situ by multicollector secondary ion mass spectrometry, unequivocally corroborate prior bulk measurements of mass-independent fractionations (MIF) in sulfur and provide additional evidence for an anoxic atmosphere on the Earth before ∼2 Ga. This technique also offers new opportunities for exploring ancient sulfur metabolisms preserved in the rock record. The presence of MIF sulfur in sulfides from a >3.8-Ga Fe-rich quartzite from Akilia (island), West Greenland, is consistent with a marine sedimentary origin for this rock.

Original languageEnglish
Pages (from-to)1635-1658
Number of pages24
JournalGeochimica et Cosmochimica Acta
Volume67
Issue number9
DOIs
Publication statusPublished - May 1 2003

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ASJC Scopus subject areas

  • Geochemistry and Petrology

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