火星の隕石 ALH84001 の炭酸塩の高温起源の可能性
1Department of Geological Sciences, Case Western Reserve University, Cleveland, Ohio 44106-7216, USA. rph@po.cwtu.edu
Nature
|July 4, 1996
まとめ
火星隕石 アラン・ヒルズ 84001 カルボネートは,低温の水ではなく,衝突時の熱いCO2豊富な液体から形成された可能性が高い. このインパクトメタソマチズムは,それらの組成と鉱物区分を説明する.
科学分野:
- 惑星科学 惑星科学
- 地質化学 地質化学
- ミネラロジー (鉱物学) とは
背景:
- アラン・ヒルズ (ALH) 84001隕石は,火星の起源で,ユニークなゾーン化された,地球以前の炭酸塩鉱物を含んでいます.
- これまでの酸素同位体研究は,火星の地殻に低温 (0-80°C) の水性流体降水を示唆していた.
研究 の 目的:
- ALH 84001炭酸塩の主要な元素の組成を分析するために.
- 炭酸塩の形成に起因する流体の組成と温度を独立に制限するために.
- 観察された炭酸特性の代替形成機構を評価する.
主な方法:
- ALH 84001隕石内の炭酸鉱物の主要元素組成の分析.
- 観測された組成物の比較と,様々な地質モデルからの予測.
主要な成果:
- 炭酸塩の組成は,低温の水性流体降水と矛盾しています.
- 観測された鉱物学と区画は,熱い (>650°C),CO2豊富な液体と宿主岩の間の反応によって最もよく説明されます.
- 併存する水性ミネラルの欠如は,高温,衝撃による形成シナリオを支持します.
結論:
- ALH 84001の炭酸塩は,高温イベント中に衝撃メタソマチズムによって形成された可能性が高い.
- インパクトプロセスは,必要な熱いCO2豊富な流体と流体経路を生成するための合理的なメカニズムを提供します.
- この形成モデルは,炭素酸で観察された酸素同位体不均衡,鉱物配列,区画パターンを調和させています.
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