最も初期の生命の痕跡の証拠を再評価する
Mark A van Zuilen1, Aivo Lepland, Gustaf Arrhenius
1Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California 92093-0236, USA. mvanzuil@ucsd.edu
Nature
|August 9, 2002
まとめ
古代の岩石のグラファイトは,初期の生命を示さないかもしれません. 新しい研究によると,このグラフィットは二次静脈における非生物学的プロセスによって形成され,初期の生命の証拠の再評価が必要である.
科学分野:
- 地質化学 地質化学
- 天体生物学 アストロバイオロジー
- 初期の地球の条件.
背景:
- 石墨の同位体成分は,古代の変形した岩石の重要なバイオマーカーです.
- イサウ上皮帯 (ISB) のグラフィートの以前の研究では,初期のアーケイア微生物の生命が示唆されていました.
- この解釈は,新しい発見により,慎重に再検討する必要がある.
研究 の 目的:
- イサウ上皮帯 (ISB) のグラフィートの起源を調査する.
- 初期のアルカインの岩石におけるグラファイトの生物学的重要性を再評価する.
- 生命の初期における既存のバイオマーカーに挑戦する.
主な方法:
- ISB岩の地質的地図作成とペトログラフィック分析.
- グラファイトおよび関連する鉱物のインサイト化学分析.
- グラファイト形成反応の熱力学モデリング.
主要な成果:
- 石墨は,ISB内の二次炭酸塩系に豊富に存在する.
- これらの静脈は,熱い液体の深部注入からメタソマチズムによって形成された.
- 石墨は,鉄炭酸塩の高温不均衡化から生じ,これは非生物学的プロセスである.
結論:
- ISBのカーボネート静脈に存在するグラファイトは,広大な微生物生態系を支えない.
- 炭酸からメタソマティック・グラファイトの形成は,代替的なアビオティック的な説明を提供する.
- ISBのグラファイトに基づいた初期の生命に関する以前の証拠は,批判的な再評価を必要としています.
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