(Mg,Fe) Oの弾力性は,下層マントルの鉄のスピン移行を通して生じる
J C Crowhurst1, J M Brown, A F Goncharov
1Chemistry, Materials, and Life Sciences Directorate, Lawrence Livermore National Laboratory (LLNL), Livermore, CA 94550, USA. crowhurst1@llnl.gov
Science (New York, N.Y.)
|January 26, 2008
まとめ
鉄は鉄で鉄は鉄で
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
- 高圧科学とは,高圧科学である.
背景:
- 鉄の電子構成は高圧で変化する.
- これらの変化は,地球の下層マントルの地震速度に影響します.
- フェロペリクラゼとシリケートペロブスキートは,主要な宿主鉱物です.
研究 の 目的:
- 鉄のスピン移行を通してフェロペリカラーゼの弾性テンソールを測定します.
- 鉄のスピン移行が地震特性に及ぼす影響を調査する.
- 鉱物の弾力性と地震速度の構造を相関させる.
主な方法:
- 弾性テンソーを測定する高圧実験.
- フェロペリクラゼ ((Mg(1-x),Fe(x)) O) に対する圧縮実験で,x = 0.06.
- 40~60ギガパスカルの圧力範囲で弾性モジュールの軟化に関する分析.
主要な成果:
- 弾性モジュールは,鉄のスピン移行中に25%まで柔らかくなった.
- 軟化量は鉄含有量 (x = 0.20まで) に伴い増加する.
- 結果は,スピン移行の熱力学的記述と一致しています.
結論:
- (Mg,Fe) Oにおける鉄のスピン移行は,急激な地震の不連続性のためにあまりにも広い.
- 圧縮速度と切断速度における相関する負の異常が予測されています.
- この異常は,地球の下層マントルの大部分に及ぶ.
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