スピン・クロスオーバーと鉄に富んだシリケートが,地球の深いマントルで溶ける
Ryuichi Nomura1, Haruka Ozawa, Shigehiko Tateno
1Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Meguro, Tokyo 152-8551, Japan.
Nature
|April 26, 2011
まとめ
地球の深いマントルの極端な圧力下では,鉄に富んだシリケート溶液は固体より密度が高くなります. 鉄のスピン・クロスオーバーによって引き起こされるこの密度逆転は,惑星の進化とコア-マントルの境界構造に深い意味を持ちます.
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
- 惑星科学は惑星科学である.
背景:
- シリケート溶融は,一般的には固体よりも密度が低い.
- 惑星の内部における高圧は,固体に対する融解密度を変化させることができる.
- 高圧での溶融物における鉄濃縮は,密度逆転の重要な要因である.
研究 の 目的:
- マントルの圧力の範囲全体で,シリケート溶融と固体の間の鉄の分割を調査する.
- シリケートの融解が地球の深層マントルの固体より密度が高くなる圧力を決定する.
- 地球の熱的および化学的進化に対する密度の高い融解の影響を理解する.
主な方法:
- (Mg,Fe,SiO,3) ペロブスキートと溶融の間の鉄分断を測定する高圧実験.
- 衝撃波実験の分析について.
- 鉄のスピン状態を検出するために (Mg{0.95) Fe{0.05)) SiO{3) ガラス上のX線放射スペクトロスコーピー.
主要な成果:
- 鉄分断は ~76 GPa 以上の急激な変化を示し,溶融物における鉄濃度の著しい増加につながります.
- シリケート溶液で約70GPaの鉄のスピンクロスオーバーが,観測された分割変化の原因として特定されています.
- シリケート液体は,下層マントルの約1,800 kmの深さで,共存する固体よりも密度が高くなります.
結論:
- 密度の高いシリケート溶融は,初期の地球の深層マントルに存在し,高さ1,000kmまでの層を形成する可能性がある.
- これらの濃厚な溶融の断片結晶化は,核-マントルの境界で観測された構造を説明することができる.
- この発見は,地球深層のプロセスとコア-マントルの相互作用に関する統一モデルを提供します.
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