上層マントルに潜入するアクティベーションボリューム
まとめ
オリヴィンに富んだ岩石におけるクリープ (V*) の活性化容量を測定した. 結果は,V*が酸素イオン拡散と関連しており,マントルの粘度推定に影響を及ぼすことを示唆している.
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
- ペトロロジー・ペトロロジーとは
背景:
- 地球のマントルの機械的振る舞いを理解することは,地動力学的プロセスにとって極めて重要です.
- オリビンは上層マントルの主要なミネラルで,そのレオロギーを制御します.
- マントル岩のクリープ変形は,温度,圧力,鉱物成分によって影響を受けます.
研究 の 目的:
- オリヴィンに富んだ岩石 (ドゥナイト) でのクリープ (V*) の活性化容量を測定する.
- V* と酸素イオンの自己拡散の関係を調べる.
- マントルの張力,張力率,粘度における変動を深さで推定する.
主な方法:
- 圧力差のクリープ実験は,ダナイトのサンプルで実施されました.
- 実験は高温 (11001350°C) と限られた圧力 (515 kbar) で行われた.
- クリープの活性化容量 (V*) は実験データから計算した.
主要な成果:
- 測定されたV*値は10.6から15.4cm3/molの範囲であった.
- 平均V*は13.4cm3/molと決定されました.
- この平均値は,オリヴィンにおける酸素イオン自己拡散の予測値に近い.
結論:
- ダナイトのクリープの活性化量は,酸素イオン拡散機構と一致しています.
- V*をフロー方程式に組み込み,クセノリフデータと組み合わせると,マントルのレオロギーを深さで推定することができます.
- この研究は,マントルの粘度と変形を制御する要因の洞察を提供します.
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