メタソマト化された石層とアルカリ性溶岩の起源
Sébastien Pilet1, Michael B Baker, Edward M Stolper
1Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA. sebastien.pilet@unil.ch
Science (New York, N.Y.)
|May 20, 2008
まとめ
融解の実験では,リトスフィアのメタソマティゼーションが,海洋殻のリサイクルではなく,アルカリ性マグマを形成する可能性があることを示唆しています. この研究は,これらの特徴的な火山岩の起源に関する新しい視点を提供します.
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
- 実験的ペトロロジーは,実験的なペトロロジーです.
背景:
- アルカリ性マグマの微量元素および同位体組成は,しばしばリサイクルされた海洋の地殻または堆積物によって説明されます.
- 代替的な仮説は,メタソマチズされた石層の源がこれらの特徴に起因する可能性があることを示唆している.
研究 の 目的:
- 塩基性マグマを生成するメタソマチ化された石層の役割を調査する.
- 実験的な溶融組成と天然のアルカリ性マグマの特徴を比較する.
主な方法:
- 溶融実験は,天然のアンフィボールに富んだ静脈で1.5ギガパスカルの温度で実施されました.
- 実験では,ホーンブレンジット (アンフィボールに富んだ岩) とルヘルゾライト (一般的なマントル岩) を溶かした.
主要な成果:
- メタソマティック静脈の部分的な溶解は,海洋と大陸のアルカリ性マグマの両方の主要なおよび微量元素の特徴を成功裏に複製しました.
- 静脈溶融とヘルゾライトの間の反応は,ネフェリニットからアルカリオリヴィンベースタルトまで,天然のアルカリベースタルトで観察された組成の変動を説明しました.
結論:
- メタソマチ化された石層の融解は,アルカリ性マグマの形成の実行可能な説明を提供します.
- これは,リサイクルされた海洋殻を主要な資源としてのみ好む支配的なモデルに挑戦しています.
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