亜鉛イソトープは,月の起源に関する証拠である

Randal C Paniello¹, James M D Day, Frédéric Moynier

¹Department of Earth and Planetary Sciences and McDonnell Center for Space Sciences, Washington University, St Louis, Missouri 63130, USA.

Nature

|October 19, 2012

まとめ

月は揮発性元素が枯渇しており,月の岩石に含まれる重い亜鉛同位体によって証明されています. これは,月形成の衝撃の後に大規模な蒸発が起こり,その巨大な衝撃の起源を支持することを示唆しています.

科学分野:

惑星科学は惑星科学である.
地質化学地質化学
同位体地質学とは,同位体地質学である.

背景:

揮発性元素は惑星の進化に不可欠ですが,初期の太陽系形成時の初期予算と枯渇はほとんど理解されていません.
月は揮発性欠乏と考えられており,揮発性損失による適度に揮発性のある元素の安定した同位素分断を意味する.
亜鉛は,揮発過程で有意な同位素分離を示し,惑星の揮発の歴史の貴重なトレーサーとなります.

研究の目的:

亜鉛イソトープを用いて月の不安定な歴史を調査する.
月面マグマ岩の揮発性枯渇の程度とメカニズムを決定する.
地球・月系における巨大衝突仮説を検証するために.

主な方法:

亜鉛イソトープの高精度測定と月の岩石における亜鉛の豊富さ.
月面の亜鉛同位体および豊富さのデータを,地球と火星のサンプルと比較.
揮発性損失プロセスを推論するために,同位素分離パターンの分析.

主要な成果:

月面のマグマ岩は,地上の岩石や火星の岩石と比較して重亜鉛同位体濃度が高く,亜鉛濃度が低い.
地球と火星は,広範囲にわたってコンドリティックな亜鉛同位体組成を示しています.
観測された変動は,小規模な火山の過程ではなく,大規模な亜鉛の蒸発,おそらく月後の形成を示しています.

結論:

月の岩石の亜鉛同位体組成は,蒸発による月の揮発性枯渇の証拠を提供します.
この発見は,地球と月の起源に関する巨大衝突の仮説を裏付けている.
この研究は,地上の惑星の早期の揮発性進化の洞察を提供します.

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