リトスフィア-アステノスフィアシステムの電気的アニソトロピーに関する実験的制約
Anne Pommier1, Kurt Leinenweber2, David L Kohlstedt3
11] University of California San Diego, Scripps Institution of Oceanography, Institute of Geophysics and Planetary Physics, La Jolla, California 92093, USA [2] School of Earth and Space Exploration, Arizona State University, Tempe, Arizona 85287, USA.
Nature
|June 12, 2015
まとめ
変形したマントル岩は,変形と一致した電気伝導性を示し,地震および電気異常を説明します. これは,融解に合わせたオリヴィン層がマントルの伝導性を制御することを示唆しています.
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
- テクトニクス (地質学) とは
背景:
- リソスフィアのプレート運動は,リソスフィア-アステノスフィアの境界付近で変形を引き起こします.
- アステノスフィアの粘度が低下し,おそらく溶けたり水に起因しているため,地震および電気の異常が説明されます.
- 変形したマントルの物質特性に対する融解の影響は十分に理解されていません.
研究 の 目的:
- 変形したマントル岩の電気特性に対する融解の影響を調査する.
- 観測されたマントルの伝導性の異常を生成する融解の役割を制限する.
- 部分的に溶けた上層マントルの電気アニソトロピーのモデルを開発する.
主な方法:
- 高温 (<900°C) と高圧 (~3 GPa) で,変形したオリヴィンと部分的に溶けた岩の電気アニソトロピー測定.
- オリヴィン集積物と部分的に溶けた岩の実験的変形.
- 層状で変形したマントルの電気伝導性の実験的モデルの開発.
主要な成果:
- 電気伝導性は,すべてのサンプルで変形方向に平行して最高です.
- 高度に切断されたオリビンは,未変形のサンプルと比較して,伝導性が10倍に増加したことを示しました.
- 切断されたオリヴィンと溶融の交互の層を持つモデルは,高い電気アニソトロピー (100倍まで) とフィールドデータを最もよく説明します.
結論:
- 変形と融解の調整は,アステノスフィアの高い電気伝導性の鍵です.
- 提案されたモデルは,メルトベアリング地域におけるマントルの導電性-深さのプロフィールを説明する.
- 電気的にアニソトロピックなアステノスフィアは,イソトロピックで導電性の下層の石層を覆っており,フィールドデータと一致しています.
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