まとめ
高圧実験により,水分化マントル岩におけるアンチゴライトの分解により,かなりの量の水分が放出されていることが明らかになった. この水は部分的な溶解を引き起こし,サブドクションゾーンでカルクアルカリ性マグマを形成する.
科学分野:
- 地質学 地質学 地質学
- 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:
- サブドクションゾーンは,地質プレートが相互作用する重要な地質学的な設定です.
- マントルの動力学とマグマ生成における水の役割は,重要な研究分野である.
研究 の 目的:
- 高圧・高温条件下におけるアンチゴライトの安定性と分解を調査する.
- シミュレートされた潜水環境におけるアンチゴライト脱水からの水分放出量を定量化するために.
- この水放出が,潜水地帯におけるマグマ発生に及ぼす影響を評価する.
主な方法:
- 制御された温度と圧力を用いた高圧実験ペトロロジー.
- 鉱物の安定性と相変化の分析.
- アンチゴライトの分解時に放出される水分量の計算.
主要な成果:
- アンチゴライトは,2GPaで720°C,3GPaで690°C,5GPaで620°Cまで安定しています.
- アンチゴライトの分解により,かなりの量のH2O (重量13%) が放出される.
- この放出された水は,上昇し,上にあるマントルのに部分的に溶け込むために最適な位置に置かれています.
結論:
- アンティゴライトの脱水は,潜水地帯の主要な水源です.
- このプロセスは,深さ100~130kmでカルク・アルカリ性マグマの生成を容易にする.
- この発見は,深水循環とその弧火山活動への影響についての理解を深めるものです.
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