メソアルカイアンオキシアと大気中の硫黄の化学変化の同位体証拠
James Farquhar1, Marc Peters, David T Johnston
1Department of Geology and ESSIC, University of Maryland, College Park, Maryland 20742, USA. jfarquha@geol.umd.edu
Nature
|October 12, 2007
まとめ
新しい研究は,メソアルカイア時代の岩石に独特の硫黄同位体信号を明らかにし,地球の初期の大気は無毒のままであったことを示しています. この発見は,初期の酸素化と大気進化に関する以前の理論に異議を唱えている.
科学分野:
- 地質化学 地質化学
- 古代気候学 (paleoclimatology) とは,古代気候学 (paleoclimatology) とは,古代気候学 (paleoclimatology) とは,古代気候学 (paleoclimatology) とは,古代気候学 (paleoclimatology) とは
- 大気科学 大気科学
背景:
- 地球の大気の進化は,低酸素レベルから高酸素レベルへの重要な移行を伴いました.
- この移行を理解することは,効率的な酸化気象の発生,海洋化学の変化,およびエアロビックエコロジーへの移行を正確に特定するために重要です.
- 約24億5千万年前,質量に依存しない硫黄同位体比の消失は,この大気変化の重要な証拠である.
研究 の 目的:
- メソアーカイアン時代の,質量に依存しない硫黄同位体信号の存在と性質を調査する.
- 初期の大気酸化のタイミングと範囲を再評価する.
主な方法:
- メソルカイア期間の堆積岩における硫黄の同位体比の詳細な分析.
- メソアルカイア時代の硫黄同位体データと他のアルカイア時代の記録の比較.
主要な成果:
- メソルカイア時代の岩石における,質量に依存しない独特の硫黄同位体信号の保存.
- この信号は,以前のアーカイア期と後のアーカイア期で見つかったものとは異なる.
- 証拠によると,初期の大気はメソアルカイア時代を通して無毒のままだった.
結論:
- メソアルカイアの大気は主に無酸素であり,初期の永久酸素化の理論に挑戦しました.
- 硫黄イソトープ記録の変動は,24億5千万年前以前に大気化学と紫外線透明性の変化を示しています.
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