Evaluating the role of microbial sulfate reduction in the early Archean using quadruple isotope systematics

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• 作者：Yanan Shen ; James Farquhar ; Andrew Masterson ; Alan J. Kaufman ; Roger Buick
• 关键词：sulfur isotopes ; early Archean barite microbial sulfate reduction ; mass-independent ; mass-dependent
• 刊名：Earth and Planetary Science Letters
• 出版年：2009
• 出版时间：30 March 2009
• 年：2009
• 卷：279
• 期：3-4
• 页码：383-391
• 全文大小：783 K

文摘

Microscopic pyrites with low ³⁴S/³²S ratios in ~ 3.47-Gyr-old sedimentary barites from North Pole, Australia have been interpreted as evidence for microbial sulfate reduction and/or sulfur disproportionation in the early Archean. We show that these microscopic sulfides have similar to slightly less negative Δ³³S and slightly more negative Δ³⁶S values compared to the enclosing sulfate crystals. This finding is consistent with a primary mass-independent signature overprinted by biological sulfate reduction, as calibrated by previous experimental laboratory culture studies. However, it is inconsistent with an overprint by abiological sulfate reduction or sulfur disproportionation, as predicted by isotope exchange theory and laboratory culture studies. Thus, our multiple sulfur isotope measurements support the contention that sulfate-reducing microbes had evolved by ~ 3.47 billion years ago.