Crが地球のコアに分裂した同位体の証拠
Frederic Moynier1, Qing-Zhu Yin, Edwin Schauble
1Department of Geology, University of California at Davis, One Shields Avenue, Davis, CA 95616, USA. moynier@levee.wustl.edu
まとめ
地球のシリケートマントルのクローム (Cr) の枯渇は,光の同位体濃縮によって証明される,コアへの分割の結果でした. この同位体シグネチャーは,初期の惑星の蓄積と酸化の間に,マグマの海の奥深くに形成されました.
科学分野:
- 地質化学 地質化学
- 惑星科学 惑星科学
- イソトープ地球化学 イソトープ地球化学
背景:
- 原始的な隕石 (コンドライト) は,地上の惑星の形成を理解するための鍵です.
- 地球のシリケートマントルのクローム (Cr) などの元素の枯渇は,揮発性とコア分割が主要な仮説として議論されている.
研究 の 目的:
- 大量シリケート地球におけるクロームの枯渇の原因を調査する.
- 揮発性またはコア分割がクロムの元素および同位体分布を説明するかどうかを判断する.
主な方法:
- 様々な隕石におけるクロム (Cr) の安定同位体の高精度測定.
- 隕石の同位体組成と大量のシリケート地球を比較する.
- Ab initio 理論的な計算. 最初から理論的な計算.
主要な成果:
- 隕石Crイソトープは,大量シリケート地球値から最大0.4ミリリットルまで逸脱する.
- シリケート地球におけるCrの枯渇は,コアへの分割に起因する.
- 核中の軽量のCrイソトープの好ましい濃縮が特定されました.
結論:
- 地球のシリケート部分のクローム (Cr) の枯渇は,コアへの優先分断によるものです.
- 観測された同位体シグネチャは,マグマの海の中央マントルの深さで核形成が起こったことを示唆しています.
- 地球の蓄積と酸化の増加は,Crの同位体組成を確立する役割を果たした.
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