地球のマントルの圧力安定化鉛貯蔵庫が隠されている
Siyu Liu1, Meng Guo2,3, Shidong Yu2
1Asian School of the Environment, Nanyang Technological University, Singapore, Singapore. siyu_liu@ntu.edu.sg.
Nature communications
|February 18, 2026
まとめ
無放射性鉛の隠された貯蔵庫は,地球のマントルの奥深くに存在しているかもしれない. 高圧鉛-硫黄化合物は,この古代の鉛を貯蔵することができ,同位体不均衡とエピソード的な放出を説明します.
科学分野:
- 地質化学 地質化学
- ミネラル物理学 ミネラル物理学
- 惑星科学は惑星科学である.
背景:
- 地球のシリケートマントルとコンドリート隕石の間に同位体不均衡が存在し,放射性でない鉛の貯蔵庫が欠けていることを示唆しています.
- 以前のモデルではコアセクストレーションが提案されていたが,シリケート地球内の鉛を分離するメカニズムは不明である.
研究 の 目的:
- 高圧鉛-硫黄 (Pb-S) 相が,地球マントルの奥深くに非放射性鉛を宿す可能性を調査する.
- 鉛イソトープの長期貯蔵とエピソード的放出のためのメカニズムを探求する.
主な方法:
- 第一原則 構造的予測.
- 高圧条件下での融点の計算.
主要な成果:
- 鉛硫化物 (PbS) は早期に結晶化し,コアマントルの境界条件では固体であり,ウラン (U) とトリウム (Th) から分離された安定した貯蔵庫を形成します.
- 硫黄に富んだ環境下では,PbSは,異なる融解行動を持つポリ硫化物相 (PbS2,PbS3) を形成し,貯蔵と限られた上向き輸送の両方を可能にします.
- これらの発見は,古代の鉛を保存し,上層マントルの非放射性シグネチャーを説明するための妥当な物理的メカニズムを提供します.
結論:
- 高圧Pb-S相は,深層マントルの非放射性鉛を隔離するための有効なメカニズムを提供します.
- マントルのリドックスと硫黄の循環は,シリケート地球の同位体進化と関連しています.
- この研究は,同位素の不一致を調和させ,マントルの地化学における鉛のダイナミックな役割を示唆している.
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