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Updated: Jul 22, 2026

07:04
High Precision Zinc Isotopic Measurements Applied to Mouse Organs
Published on: May 22, 2015
地球上の古代オスミウム同位体貯蔵庫の証拠
1Geological and Environmental Sciences, 320 Lomita Mall, Stanford University, CA 94305-2115, USA. meibom@pangea.stanford.edu
まとめ
地球のマントルの古代プラチナグループ元素貯蔵庫は,初期の内核形成を示唆しています. イリドスミン粒子は,非常に放射性オスミウム同位体比を示し,地球の増殖直後の核-マントルの相互作用を指している.
科学分野:
- 地質化学 地質化学
- 同位体地質学とは,同位体地質学である.
- 惑星科学は惑星科学である.
背景:
- クラマス山脈のオフィオライトから採取したイリドスミン粒子は,異常な地化学的サインを示している.
- これらの粒子は,高放射性オスミウム同位体比 (186Os/188Os) と256から2644百万年までの古代のRe-Osの年齢を有しています.
- これは,プラチナ・オスミウム (Pt/Os) の比率を持つ古代のプラチナ群元素貯蔵庫の存在を示唆している.
研究 の 目的:
- 古代のプラチナグループ元素貯蔵庫の起源を調査する.
- これらの貯水池が初期の地球プロセス,特にコア形成に及ぼす影響を調査する.
- イリドスミンOsの同位体組成物が外核のシグネチャーとして機能できるかどうかを判断する.
主な方法:
- プレイスター埋蔵地からのイリドスミン粒子の分析.
- オスミウム (Os) とレニウム (Re) の同位体組成をRe-Osジオクロノロジーを用いて決定する.
- 地質化学モデリングにより,超コンドリート上部のPt/Os比率の潜在的な形成メカニズムを評価する.
主要な成果:
- イリドスミン粒子は,極めて放射性186Os/188Osの比率を示し,最小のRe-Osは264億年まで老化します.
- これらの発見は,Pt/Os比率が超コンドリート上にある古代貯水池の存在を示しています.
- 観測されたPt/Os比は,外核の内核結晶時の分割と一致しています.
結論:
- イリドスミンOsの同位体組成は,地球の外核とのつながりを示唆しています.
- これらのOs同位体組成が,外核のサインであるならば,それは内核の非常に初期の形成を暗示する.
- 内部核は,地球の収縮後の最初の数億年以内に形成され,以前考えられていたよりもかなり早く形成された可能性が高い.
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