メソプロテロゾーイク期の地上の環境の初期の酸素化
John Parnell1, Adrian J Boyce, Darren Mark
1School of Geosciences, University of Aberdeen, Aberdeen AB24 3UE, UK. j.parnell@abdn.ac.uk
Nature
|November 12, 2010
まとめ
地化学的なデータは,古代の地上の岩石における重要な硫黄同位体の分断を明らかにし,メソプロテロゾーイク時代の酸素に富んだ条件を示しています. これは,複雑な硫黄循環と酸素に依存した生命体の初期の進化を示唆しています.
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
- バイオジオケミストリー バイオジオケミストリー
背景:
- 古代の堆積岩からの地化学データは,地球の大気と海洋の進化を追跡します.
- 重要な酸素化のイベントは,メタゾーン進化と関連した,古プロテロゾーイクと後期プロテロゾーイク時代に提案されています.
- 硫黄同位素分離 (Δ(34) S) データは,1 Gyr ほど前に<25 ‰ から ≥50 ‰ へのシフトを示しており,微生物の硫黄循環が進化しているとして解釈されています.
研究 の 目的:
- 地上メソプロテロゾーイク時代における硫黄同位体の分断を調査する.
- この地質学期における理解が乏しい硫黄の循環を特徴づけるために.
- 観測された分断が大気中の酸素レベルと微生物の進化に及ぼす影響を評価する.
主な方法:
- 古代の堆積物連鎖からの地化学データの分析.
- スコットランドの地上のメソプロテロゾーイク時代の岩石 (1.18 Gyr 古い) で硫黄同位素比 (Δ34S) の測定.
- 微生物の硫黄循環 (硫酸還元,硫化酸化,不均衡) の文脈における同位体データの解釈.
主要な成果:
- 1.18 Gyr 古い地上のメソプロテロゾーイク連続における 50 ‰ を超える Δ34S 値の発見.
- 硫黄の不均衡の証拠,おそらく硫黄酸化細菌が関与している,赤い床と湖面黒のシェール.
- これらの発見は,特殊な生物を支えるのに十分な酸素を備えたメソプロテロゾイク時代の陸生環境を示唆しています.
結論:
- メソプロテロゾイク期の陸上の環境は,海洋硫黄の記録によって先ほど示されたより早く酸素化された.
- 硫黄イソトープ分化の有意な存在は,酸素豊富な環境に適応した活性微生物コミュニティを暗示しています.
- この研究は,地球の初期の酸素化と微生物生命の進化に関する重要な洞察を提供します.
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