18億5千万年前のサドベリーの衝撃構造に含まれるフルレレン
L Becker1, J L Bada, R E Winans
1Scripps Institution of Oceanography, University of California at San Diego, La Jolla 92093-0212B, USA.
Science (New York, N.Y.)
|July 29, 1994
まとめ
フルレレン (C60とC70) はサドベリーの衝撃構造で発見されました. 硫黄は18億5千万年以上にわたってそれらの酸化を防止し,インパクターから地球外の起源を示唆しました.
科学分野:
- 地質化学 地質化学
- アストロケミストリー アストロケミストリー
- インパクト・クレーター研究
背景:
- フルレレン (C60およびC70) は,地球外起源の可能性のある炭素アロトロップである.
- サドベリーの衝突構造は,地球外の大規模な衝突イベントのユニークな地質学的記録を提供します.
- 衝突時のフラーレンの保存を理解することは,天体生物学と地化学にとって極めて重要です.
研究 の 目的:
- サドベリーの衝撃構造の衝撃で発生したブレクシア内のフルレレンを特定し,特徴づけること.
- 衝撃環境における地質学的時間尺度におけるフラーレンの保存メカニズムを調査する.
- インパクトサイトにおけるフラーレンの発生を基に,フラーレンの潜在的地球外起源を探求する.
主な方法:
- フラーレンの検出のためのレーザー消吸収質量スペクトロメトリ (LDMS).
- 感度と特徴を高めるために,レーザー消吸収後離子化質量スペクトロメトリー (LDPI-MS) を使用します.
- 精密な質量測定と同位体分析のための高解像度電子衝突質量スペクトロメトリー (HR-EI-MS).
- ブレッチャマトリックスと関連する鉱物相の地化学分析.
主要な成果:
- フルレレン (C60とC70) は,サドベリー衝突構造からのオナピング形成のブレキアで明確に特定されました.
- C60の濃度は百万分の1の範囲であることが判明しました.
- 証拠によると,フラーレンは,ボリデーの炭素からインパクトプラームで合成されたことを示唆しています.
- 硫化物-シリケート複合体として存在する硫黄は,185億年以上にわたってフルレンの酸化を阻害したようです.
結論:
- この発見は,地上の衝突構造にフラーレンの存在を確認し,超高速衝突時にフラーレンの形成を支えている.
- フルレレンの保存は,硫化シリケート複合体内の封じ込みに起因し,酸化から保護しています.
- これらの発見は,衝突イベントにおける炭素循環の理解と,地球と他の惑星系上の地球外有機分子の保存の可能性に重大な意味を持ちます.
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