ネオプロテロゾイク期の氷河期後のキャップ炭酸にメタンが浸透しているという安定した同位体証拠がある
Ganqing Jiang1, Martin J Kennedy, Nicholas Christie-Blick
1Department of Earth Sciences, University of California, Riverside, California 92521, USA. ganqing@mail.ucr.edu
Nature
|December 20, 2003
まとめ
重度の氷河期後に発見されたネオプロテロゾイクキャップ炭酸は,メタン水素の不安定化に関する証拠を提供します. これは,メタンの放出だけでなく,雪球のような地球の条件が,これらのユニークな地質学的形成に影響を与えたことを示唆しています.
科学分野:
- 地質学 地質学 地質学
- 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
- 地質化学 地質化学
背景:
- 後期ネオプロテロゾーイク氷河期 (約. 600万年前) は,異常なキャップカーボネート堆積物と関連している.
- キャップ炭酸は,議論の余地のある起源を持つ,著しい負の炭素同位体遠征を示しています.
- 主な仮説は2つ",スノーボール・アース"の余波 (生態系崩壊) または脱氷期におけるメタン水素の不安定化である.
研究 の 目的:
- ネオプロテロゾイク期のキャップ炭酸と関連する炭素同位体異常の起源を調査する.
- "スノーボール地球"仮説に対するメタン水素不安定化仮説の検証.
- 氷河期後の堆積におけるメタンの役割の直接的な証拠を提供すること.
主な方法:
- カップカルボネートサンプルにおける炭素同位体の分析.
- カップ炭酸岩石構造のペトログラフィック調査.
- 中国南部のネオプロテロゾーイク期のキャップカルボネート遺跡からのフィールドデータ収集.
主要な成果:
- 炭素同位体および石版データは,メタンの影響を受けたプロセスの証拠を明らかにしています.
- 発見は,脱氷過程におけるメタン水素の不安定化の役割を直接支持しています.
- データによると,メタンの有意な放出がキャップ炭酸塩の形成に寄与したことを示している.
結論:
- メタン水素の不安定化は,ネオプロテロゾーイクキャップの炭酸堆積に大きく寄与する要因である.
- この仮説は,観察された炭素同位体異常を,極端で長期の生態系崩壊を必要とせずに説明します.
- この発見は,氷河期後の地質学的特徴について,より極端な環境的な説明を提供している.
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