Using multiple sulfur isotopes to understand the Earth's surface environments during the Archean era

• OTAKE Tsubasa

  Department of Earth Science, Graduate School of Science, Tohoku University (Present address) Institute for Geo-Resourses and Environment, National Institute of Advanced Industrial Science and Technology

• WATANABE Yumiko

  The NASA Astrobiology Institute and Department of Geosciences, The Pennsylvania State University

Bibliographic Information

Other Title

• 硫黄同位体から読み取る太古代地球の表層環境 : 現状とその問題点
• イオウ ドウイタイ カラ ヨミトル タイコダイ チキュウ ノ ヒョウソウ カンキョウ : ゲンジョウ ト ソノ モンダイテン

Abstract

Since the discovery of Anomalous Isotope Fractionation (AIF) of sulfur, or more commonly termed Mass-Independent Fractionation (MIF) of sulfur, in many sedimentary rocks older than 2.45Ga, and its virtual absence in younger rocks, the AIF record has been cited by many researchers as unequivocal evidence for a dramatic change from an anoxic to oxic atmosphere around 2.45Ga. However, multiple sulfur isotope data from these natural samples have been interpreted based on the assumption that sulfur chemistry in gas phase is only responsible for AIF of sulfur in nature. The objective of this review is to evaluate this assumption. First, results of ab initio calculations for equilibrium isotope exchange between S-bearing species show that deviations from the mass-dependent relationships during equilibrium processes are much smaller than those found in Archean sedimentary rocks. Consequently, AIF requires a property that is a discontinuous function of mass (e.g., nuclear volume, magnetic moment, asymmetry of molecules, isotopic abundance). The number of bound states may be another discontinuous function of mass, which fractionates S isotopes anomalously during chemisorption at a high temperature (e.g., >100℃). A recent experimental study also showed that thermochemical sulfate reduction by simple amino acids produces AIF of sulfur. These results suggest that an alternative process, such as reactions between organic matter in sediments and sulfate-rich hydrothermal solutions, may have caused AIF signatures of sulfur in Archean sedimentary rocks.

Journal

• Chikyukagaku

  Chikyukagaku 45 (4), 251-264, 2011-12-25

  The Geochemical Society of Japan

Keywords

• Sulfur isotope
• Mass-dependent fractionation
• Anomalous isotope fractionation
• Evolution of atmosphere
• Thermochemical sulfate reduction

Details

• CRID: 1390282680718970880
• NII Article ID: 110008913807
• NII Book ID: AN00141280
• DOI: 10.14934/chikyukagaku.45.251
• ISSN: 21885923
• ISSN: 03864073
• NDL BIB ID: 023464451
• Web Site: http://id.ndl.go.jp/bib/023464451
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I023464451
• Text Lang: ja
• Data Source:
  • JaLC
  • NDL
  • CiNii Articles
  • KAKEN
• Abstract License Flag: Disallowed