まとめ
マントル・ペリドトイト (Mantle peridotite) とは,マントルのペリドトイト (Mantle peridotite) と呼ばれる.
科学分野:
- 地質化学 地質化学
- ペトロロジー・ペトロロジーとは
- ミネラル物理学 ミネラル物理学
背景:
- 中洋の山脊での脱ガス化や潜水地帯での再水分化などのマントルの過程は,C-H-O流体の種化に影響を与えます.
- マントル・ペリドータイトの酸化状態は,これらのマントルプロセスと流体進化と密接に関連しています.
研究 の 目的:
- マントルのペリドータイト・キセノリトの酸素流動性 (fo(2) を研究するために,様々な地質学的な環境から採取した.
- 地球のマントルの酸化状態,流体組成,地質学的過程の関係を理解する.
主な方法:
- 大陸と海の環境からのペリドータイト・キセノリトの分析.
- ファヤライト・マグネチット・クォーツ (FMQ) のバッファに対して,酸素流動性 (fo(2) の測定.
- 微量元素と同位体シグネチャの試験により,流体と岩の相互作用を特定する.
主要な成果:
- コンチネンタル・ペリドタイト・キセノリトは,広範囲のFO2 (FMQに対して-1.5から+1.5ログ単位) を示し,拡張領域では値が低下している.
- サブダクションゾーンからの酸化したゼノリト (fo(2) >FMQは,アンフィボールを含有し,流体相互作用の証拠を示しています.
- オーシャンリッジのペリドータイトは,ミドルオーシャンリッジ玄武岩 (MORB) グラスと一致する,FMQに相対して約0.9ログ単位減少 (平均fo(2) しています.
結論:
- 海洋のアステノスフィアは減少しており,CO2とH2Oが支配的な流体種であり,MORB液体を残留ペリドチートと結びつけています.
- 大陸の岩層圏に潜伏ゾーンが入ると,アステノスフィアと潜伏のシグネチャーが混合したゼノリスが形成されます.
- 石層流体には,CO2とH2Oが優勢であり,原生炭素 (ダイヤモンド) の安定性は,深さとガーネットのFe3+含有量に関連しています.
関連する概念動画
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