炭酸コンドライト隕石は,過去100万年以内に流体流出を経験しました
Simon Turner1, Lucy McGee2, Munir Humayun3,4
1Department of Earth and Environmental Sciences, Macquarie University, Sydney, NSW 2109, Australia. simon.turner@mq.edu.au.
まとめ
原始的な隕石は 最近の流体流動の証拠を示し,ここ数十万年の間にウランの移動を示しています. これは,彼らの親体はまだ氷を含んでいる可能性を示唆し,初期の太陽系プロセスの理解に影響を与えます.
科学分野:
- 宇宙化学
- 惑星科学
- 地化学
背景:
- 炭酸性コンドリート隕石は太陽系の原始的な物質である.
- これらの隕石は 地球への水の供給を理解するために 極めて重要です
- 初期の流体流 (<400万年) は隕石の親体で知られている.
研究 の 目的:
- 隕石の親体の流動を調査する
- 炭酸性コンドライトの短命なウラン同位体の変化を分析する.
- 宇宙線曝露の相対的なウラン移動のタイミングを決定する.
主な方法:
- 短命のウラン同位体 (234-U,238-U,230-Th) の分析
- 余剰ウラン (234-U/238-Uと238-U/230-Th) の測定
- 流体フローの時間スケールと宇宙線被曝年齢の比較
主要な成果:
- 234ウランが238ウランと238ウランが230ソリウムを超えていることが検出されました.
- 流体移動性U6+イオンが 過去数十万年の間に 移動したことを示しています
- いくつかの隕石では,この流体流は,親体からの放出よりも最近発生しました.
結論:
- 最近の流体流は,おそらく衝突加熱によって駆動され,隕石の親体に発生しました.
- この流体活動は 氷が溶けた後に発生し 元の体はまだ氷を保持している可能性があることを示唆しています
- この発見は,太陽系初期の熱の歴史と組成に関する新しい洞察を提供します.
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