ラテニウムイソトープは,太陽系内部の先端の起源を示す証拠である
Mario Fischer-Gödde1, Thorsten Kleine1
1Institut für Planetologie, University of Münster, Wilhelm-Klemm-Strasse 10, 48149 Münster, Germany.
Nature
|January 28, 2017
まとめ
地球のマントルは 隕石物質の"遅い層"を含んでいる. ルテニウムの同位体分析により,このベネアは太陽系外部の炭酸性コンドライトから生じていないことが明らかになり,地球の水と揮発性物質の主な源としての役割は否定された.
科学分野:
- 地化学
- 宇宙化学
- 惑星科学
背景:
- 地球のマントルは,核形成後に添加された隕石物質の"遅いフェニヤー"に起因する,高度に siderophile 要素の過剰を持っている.
- この遅い層の起源は (太陽系内側と外側) 地球の揮発性物質と水の源を理解するために重要である.
研究 の 目的:
- ルテニウム (Ru) のイソトープを分析することによって,地球の遅いフェニアの起源を調査する.
- 地球の揮発性物質の潜在的源である 炭酸性コンドライトが 遅い層の源であるかどうかを判断する
主な方法:
- 炭酸性コンドライトを含む様々なコンドライトにおけるルテニウム (Ru) の同位体組成の分析.
- コンドリティックなRuイソトープデータと,地球マントルの既知のRuイソトープ組成の比較.
主要な成果:
- 炭酸性コンドライトを含むすべての分析されたコンドライトは,地球のマントルとは異なるRu同位体組成を示している.
- エンスタチットから通常の炭酸性コンドライトへのRu同位体異常の増加の明確な傾向が観察されました.
- この傾向は,より大きな太陽中心の距離で形成された物質は,より大きなRu同位体異常を持っていることを示しています.
結論:
- この研究は,太陽系外部の地殻の起源を否定している.
- 遅いフェニヤはおそらく地球上の揮発性物質と水の主要な源ではなかったので,以前の仮説に挑戦した.
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