深層マントルのクリプトンは,地球の初期の炭素物質の蓄積を明らかにします
Sandrine Péron1, Sujoy Mukhopadhyay2, Mark D Kurz3
1Department of Earth and Planetary Sciences, University of California, Davis, Davis, CA, USA. scperon@ucdavis.edu.
Nature
|December 16, 2021
まとめ
深いマントルのイソトープは 初期の地球に蓄積された炭素物質を示唆しています この発見は,太陽系の外部惑星系を含む複数の源からの揮発性および耐火性の元素の同時蓄積を示しています.
科学分野:
- 惑星科学
- 地化学
- 宇宙化学
背景:
- 地球への揮発性物質 (炭素,窒素,水) の起源と運送を理解することは,居住可能な惑星の発展を理解するために不可欠です.
- 地球への揮発性輸送メカニズムは 科学的な議論の対象であり続けています
- クリプトンのイソトープは,異なった地球外源における重要なイソトープの変動により,揮発性の配送に関する貴重な洞察を提供します.
研究 の 目的:
- クリプトンイソトープを用いて 地球に揮発性物質を送り込む 原因とタイミングを調査する
- 大気汚染を回避するために 原始的なマントルのイソトープを分析する
- 地球の蓄積と変動のモデルを 制限するためです
主な方法:
- ガラパゴス諸島とアイスランドのマントルの深層から採取したクリプトンイソトープの分析
- 測定されたクリプトンの同位体組成を,地球外の既知の貯水池 (コンドライト) と地球の大気との比較.
- ヘリウム,ネオン,トラングステンの 原始的な同位体組成のサンプルを使用します.
主要な成果:
- クリプトンの同位体組成は,86Krを除いて,コンドリートと大気中のクリプトンの混合物と似ています.
- これらの発見は,原始地球による早期の炭素物質の蓄積を裏付けている.
- 炭素系隕石と比較して,ニュートロンに富んだ86Krの顕著な欠乏が観測され,核合成異常が示唆された.
結論:
- この結果は,地球の大気中の高貴なガスを説明するために,水力学的損失とマントルのガスの排出にのみ依存するモデルに挑戦しています.
- 観測されたクリプトンの同位体は 揮発性元素と耐火性の元素の 同時増殖を示しています
- これは,地球の揮発性および耐火性の成分が,太陽系の外部惑星系を含む複数の源から生じたことを示し,揮発性元素の核合成異常を指している.
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