Sulfur and carbon isotope analyses of the 2.7 Ga Jeerinah Formation, Fortescue Group, Australia

Takeshi Kakegawa, Yukio Kasahara, Ken Ichiro Hayashi, Hiroshi Ohmoto

研究成果: Article査読

8 被引用数 (Scopus)

抄録

Sulfur and carbon isotope ratios have been determined on carbonaceous shales of the 2.7 Ga Jeerinah Formation, Hamersley Group, Australia. The analyses were performed using the Nd-YAG laser micro-probe method. The δ13C((PDB)) values of organic matter range from -38.3‰ to -35.1‰ with an average of -37.0‰ (44 analyses). These carbon isotope compositions support the previously proposed hypothesis that methanogens and methanotrophs were involved in the carbon cycles in the 2.7 Ga Hamersley ocean. Sulfur isotope compositions are ranging from +0.4‰ to +10.2‰ with an average of +4.6‰ (90 analyses). A notable feature is variable δ34S values within a micro-scale area; approximately 6 to 7‰ variations of δ34S values were detected within 5 x 5 mm areas. Such δ34S variations clearly indicate that pyrites in the Jeerinah shales were formed as a result of the sulfate reduction. This suggests that the 2.7 Ga Hamersley ocean contained appreciable amount of dissolved sulfate, opposing to the previously popular H2S-rich ocean model. Because of no evidence for the hydrothermal alterration on the examined samples, pyrites in the 2.7 Ga Jeerinah shales were most likely formed by the biological sulfate reduction in sediments.

本文言語English
ページ(範囲)121-133
ページ数13
ジャーナルGeochemical Journal
34
2
DOI
出版ステータスPublished - 2000

ASJC Scopus subject areas

  • 地球物理学
  • 地球化学および岩石学

フィンガープリント

「Sulfur and carbon isotope analyses of the 2.7 Ga Jeerinah Formation, Fortescue Group, Australia」の研究トピックを掘り下げます。これらがまとまってユニークなフィンガープリントを構成します。

引用スタイル