マントルの移行領域の深さにおける寒い潜水板における磁気
I Kupenko1, G Aprilis2,3, D M Vasiukov2,3,4
1Institut für Mineralogie, University of Münster, Münster, Germany. kupenko@uni-muenster.de.
Nature
|June 7, 2019
まとめ
地球のマントルの鉄に富んだヘマタイト (α-Fe2O3) は,深層の移行領域の深さでも磁性であり,逆転時に潜在的に深層の磁気異常と仮想地磁気極の経路を説明します.
科学分野:
- 地理学
- 鉱物物理学
- 地球科学
背景:
- 地球の地殻とマントルの境界 (モホロヴィチク不連続) は,磁気地殻と非磁気マントルを分離すると考えられていた.
- 地質学的データとマントルのクセノライトは,マントルの内部に磁気源が存在することを示唆している.
- 鉄酸化物,特にヘマタイト (α-Fe2O3) は,高い臨界温度のため,深い磁気異常の主な候補である.
研究 の 目的:
- 鉄酸化物,特にヘマタイトの磁気特性を,地球のマントルに関連する高圧および高温で調査する.
- マントルの条件下でFe2O3ポリモルフの磁気移行と臨界温度を決定する.
- 観測された地磁気現象に対する深層マントルの磁気源の貢献を評価する.
主な方法:
- シンクロトロン・モッズバウアー源光譜を用いた.
- マントルの圧力-温度条件 (最大90GPaと1,300K) を複製するために,レーザーで加熱されたダイヤモンドアンビルセルを使用しています.
- ヘマタイトの磁気性を中心にFe2O3ポリモルフを分析した.
主要な成果:
- ヘマタイト (α-Fe2O3) は,地球の移行地帯に相当する深さで,特に寒い潜水地熱で磁性特性を発揮します.
- 西太平洋の磁性岩層を特定した
- これらの深層磁気源と逆転時の地球の仮想地磁気極の好ましい経路の間の空間的相関を観察した.
結論:
- ハメタイトは,マントルの移行圏内に深い磁気源を作り出すことができます.
- これらの深い磁気源は,地磁気データと仮想地磁気極の経路の解釈に影響を与える可能性があります.
- この発見は,地球深層の磁場モデルの再評価と,活発なダイナモが欠けている他の惑星体の研究を必要とします.
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