地球の"欠けている"ニオビウムは,地球の中心にあるかもしれない
Nature
|May 9, 2001
まとめ
ニオビウムとバナジウムは,地球の核形成の過程で同様の行動をとります. これは,ニオビウムがバナジウムと共に核に入ったことを示唆し,深いマントルのニオビウム貯蔵庫の必要性を否定している.
科学分野:
- 地質化学 地質化学
- 惑星科学は惑星科学である.
- 地球科学 地球科学 地球科学
背景:
- 地球の核形成には,金属とシリケート相の分離が含まれていた.
- バナジウムのような適度な siderophile 要素は,シリケートマントルで枯渇し,コアへの侵入を示唆しています.
- 耐火性リトフィール元素 (例えば,カルシウム,希土元素) は枯渇していないので,シリケート部分に残っていることを示している.
研究 の 目的:
- 液体金属と液体シリケートとの間のニオビウム (Nb) の分割行動を調査するために.
- 地殻と上層マントルのNbの枯渇が深層マントルの貯蔵所を必要とするかどうかを判断する.
- 核に入る元素として知られるバナジウム (V) とのNb分割を比較する.
主な方法:
- コア-マントルの分化をシミュレートする高圧実験.
- 金属溶融とシリケート溶融の間の元素分割の分析.
- ニオビウムとバナジウムの分割係数の比較.
主要な成果:
- ニオビウムとバナジウムは,高圧下では,液体金属と液体シリケートとの間に実質的に同一の分割行動を示します.
- Nbの分割は,適度な siderophile 元素であるVの分割と一致しています.
- 地殻と上層マントルの観測されたNbの枯渇は,隠された貯蔵庫ではなく,コアの分割によって説明できます.
結論:
- ニオビウムは,惑星の形成時にバナジウムと共に地球の中核に入った可能性が高い.
- 深層マントルのニオビウム豊富な貯水池の概念は,観測された枯渇を説明するために不要です.
- この発見は,地球の初期の化学的分化と元素の分布についての理解を洗練します.
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