スピネル後のMg2SiO4の変換と,それが660キロメートルの地震断絶と関係していること
1Department of Geosciences, Princeton University, Princeton, New Jersey 08544, USA. sangshim@princeton.edu
Nature
|June 1, 2001
まとめ
660キロメートルの地震の不連続は,地球のマントルの鉱物相変化と関連しています. 新しい in situ 実験は,この変換が予想される深さで発生することを確認し,地震データと一致しています.
科学分野:
- 地質物理学 地質物理学とは地質物理学です.
- ミネラル物理学 ミネラル物理学
- 高圧地化学 高圧地化学
背景:
- 660キロメートルの地震の不連続は,地球のマントルの性質に大きな変化をもたらしています.
- この不連続性は,伝統的に (Mg,Fe) 2SiO4.4のスピネル後の変換に起因していた.
- 以前の in situ 研究では,この変換は低圧で発生し,660 km の不連続性との関連が疑問視されたと示唆されていた.
研究 の 目的:
- 高圧および高温下でのMg2SiO4のin situ相変換を調査する.
- Mg2SiO4.4におけるスピネル後の移行の正確な圧力-温度条件を決定する.
- 実験結果と660kmの不連続性の地震観測を調和させるため.
主な方法:
- In situシンクロトロンX線 difrakcion. インサイトシンクロトロンX線 difrakcion.
- ダイヤモンド・アンビル・セルで二面レーザー加熱.
- Mg2SiO4を20から36GPaの圧力で実験的に研究した.
主要な成果:
- Gamma-Mg2SiO4からMgSiO3-perovskiteとMgO (periclase) への相変換は,前向きと逆方向の両方で観察されました.
- このスピネル後の変換の圧力および温度条件は,660kmの断続性に対する地震データと一致することが判明しました.
- これは,以前のインシット・マルチ・アンヴィル・プレス実験の結果と矛盾する.
結論:
- Mg2SiO4のスピネル後の変換は,660kmの地震断絶と一致しています.
- レーザーで加熱されたダイヤモンド・アンビル・セルのような高圧実験技術は,地球深層のプロセスを理解するための重要なデータを提供します.
- マントルの不連続性の正確な位置と性質は,これらの高度な in situ 方法によってよりよく制限されます.
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