まとめ
MgSiO ((3) ペロブスキットは,高圧と高温で構造的変化を起こします. この発見は,その性質を地球の下層マントルに適用する際の注意を促し,マントル全体のコンベクションをサポートします.
科学分野:
- ミネラル物理学 ミネラル物理学
- 地質化学 地質化学
- 高圧地質物理学 高圧地質物理学
背景:
- マグネシウムシリケートペロブスキート (MgSiO3) の振る舞いを理解することは,地球の深い内部をモデル化するために重要です.
- 以前の研究では,Pbnm相の性質に依存しており,潜在的に下層マントルの状態を誤って表している.
研究 の 目的:
- MgSiO3ペロブスキートの高圧,高温構造的振る舞いを調査する.
- 現在のMgSiO3ペロブスキートデータの地球下層マントルの適用性を決定する.
主な方法:
- 現場でのX線 difraktion実験は,DIA型立方アンビル装置 (SAM 85) を使用して行われました.
- 測定は,7.3ギガパスカルの圧力と600ケルビン以上の温度で行われた.
主要な成果:
- MgSiO3ペロブスキットは,Pbnm対称性のオーソロンビック構造から,7.3GPaで600K以上の別のペロブスキット構造へと変化する.
- トランジション全体で0.7%の目に見える量増加が観察されました.
- ユニット・セル・ボリュームは,温度が移行値を下回り,上昇するとともに,線形膨張を示した.
結論:
- Pbnm相の物理的性質は,地球の下層マントルには適用できないかもしれません.
- 密度分析は,下層マントルの条件下で10.4%重量%の鉄を含むパイロライト組成を示唆しています.
- データは全マントルのコンベクションを支持し,化学的に均質なマントルが妥当であることを示唆しています.
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