中洋のペリドータイトの融解の程度を示す指標として,主要元素と微量元素を組み合わせた
E Hellebrand1, J E Snow, H J Dick
1Max-Planck-Institut für Chemie, Postfach 3060, D-55020 Mainz, Germany. ehelle@mpch-mainz.mpg.de
Nature
|April 5, 2001
まとめ
アビッサル・ペリドータイトは融解をなくし,海殻を形成し,マントルの組成を変更する. 新しい研究は,クリノピロキセンの希土元素とスピネル化学を結びつけ,マントルの残留物に対する定量的な溶解指標を作成しています.
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
- 海洋学 海洋学 海洋学
背景:
- アビッサル・ペリドータイト (Abyssal peridotites) は,最上層の亜海洋マントル岩である.
- これらの岩は,ベースルティック溶融を失い,海殻を形成します.
- このプロセスは,稀土元素を含む主要元素と微量元素のペリドータイトを枯渇させます.
研究 の 目的:
- ペリドタイトから溶融の抽出に関する定量的な理解を確立する.
- 主要元素の枯渇と微量元素の枯渇の間の相関の欠如に対処するために.
- マントルの残留物に対する信頼性の高い融解指標を開発する.
主な方法:
- インド中央の山脊からのアビスカル・ペリドータイトの分析.
- 電子およびイオンマイクロソーブのデータを利用する.
- クリノピロキセンの重希土元素とスピネルのCr/Cr+Al比を相関する.
主要な成果:
- アビサルのクリノピロキセンの重稀土元素と,共存するスピネルのCr/Cr+Al) の比率の間に強い相関が認められた.
- この相関は,適度な互換性のない要素では成立するが,高度な互換性のない要素では弱まる.
- マントルの残留物に対する定量的な融解指標が開発されました.
結論:
- 確立された相関は,ペリドータイトの部分融解を定量化するための新しい方法を提供します.
- この指標は,マントルの融解プロセスを地力学的変数と関連付けるために使用できます.
- この発見は,海洋の地殻形成とマントルの分化についての洞察を提供します.
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