タタホイーン隕石における炭酸塩の形成
J A Barrat1, P Gillet, C Lécuyer
1Université d'Angers, Laboratoire de Géologie, 2 Boulevard Lavoisier, 49045 Angers Cedex, France.
まとめ
タタオウイン隕石は,二次カルシット鉱物と棒状の形態が,地球への曝露の63年後に骨折に現れる証拠として,地上汚染を示しています. 炭素同位体分析は,これらの特徴が隕石そのものではなく,地球に由来することを確認しました.
科学分野:
- 地質化学 地質化学
- ミネラロジーは,鉱物学です.
- 惑星科学 惑星科学
背景:
- 隕石は,地球外の物質や過程についての洞察を与えてくれます.
- 地上からの汚染は,時間とともに隕石の組成を変化させる可能性があります.
- 1931年,タタフイン隕石がチュニジアに落下した.
研究 の 目的:
- タタホイン隕石の地上汚染を調査する.
- 隕石の断裂で発達した二次鉱物や形態を特徴付けるために.
- これらの二次的な特徴の起源を決定するために.
主な方法:
- 異なる時期に収集された隕石のサンプルを比較分析.
- 二次鉱物の成長のための骨折の顕微鏡検査.
- 隕石と周囲の土壌における炭酸塩の炭素同位体分析 (δ13C PDB)
主要な成果:
- 1931年の隕石サンプルでは,骨折がみられたが,二次鉱物は見つかりませんでした.
- 1994年のサンプルは,骨折にカルシット集積物と棒状の形を示した.
- 二次性炭酸塩の炭素同位体値は,地上の土壌と一致し,地球起源を示した.
結論:
- タタオウイン隕石は,地球上での63年間,地球上の汚染を大幅に経験しました.
- 二次カルシットと関連する微細構造は,地上の気象の影響により,落下後に形成されました.
- 同位体分析は,隕石の地外物質と地上の物質を区別するための信頼できる方法である.
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