マントルの融解中にプラチナ群の元素の分断
Conny Bockrath1, Chris Ballhaus, Astrid Holzheid
1Institut für Mineralogie, Universität Münster, Corrensstrasse 24, 48149 Münster, Germany. bockrat@nwz.uni-muenster.de
まとめ
アステノスフィアの上層マントルには,2つの安定した硫化物相が存在する:単硫化物と硫化物溶融. これらの相は,それぞれ残層マントルとベースルティック成分における貴金属の分布を制御する.
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:
- 上層マントルの硫化物相の組成と振る舞いは,貴金属 (プラチナ群の元素) の循環を理解するために重要である.
- 以前の研究では,マントルの溶解と溶融分離の間に異なる硫化物相の異なる役割が完全に解明されていません.
研究 の 目的:
- 上層マントルの条件下にある硫化シリケート系における硫化相の安定性と分断を調査する.
- これらの硫化物相が,残留マントルの貴金属含有量と分離シリケート溶液の貴金属含有量にどのように影響するかを決定する.
主な方法:
- 硫化物-シリケート系を用いた実験的石油学.
- フェーズ組成と貴金属分割の分析.
主要な成果:
- 2つの異なる硫化物相が安定している: Os,Ir,Ruで濃縮された結晶単硫化物と,Rh,Pt,Pdで濃縮された硫化物溶融.
- モノスルフィドは,シリケート溶融分離中に固体残留物の中に留まり,残留マントルの貴金属シグネチャーを制御します.
- 硫化物溶液は,シリケート溶液に滴として組み込まれ,玄武岩マグマの貴金属在庫を定義します.
結論:
- モノスルファイドとスルファイドの溶融相の異なる行動は,残層マントルとマグマの間の貴金属の明確な分割につながります.
- この理解は,マントルの過程と,マグマ性鉱石の鉱床におけるPGEsの起源を追跡するために非常に重要です.
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