海殻の深層マントルの循環:ダイヤモンドとその鉱物含有物からの証拠
M J Walter1, S C Kohn, D Araujo
1School of Earth Sciences, University of Bristol, Bristol BS8 1RJ, UK. m.j.walter@bristol.ac.uk
Science (New York, N.Y.)
|September 17, 2011
まとめ
下層マントルから沈下した海洋地殻が戻り,深層の炭素循環に関する最初の地質学的な証拠を提供します. 超深層のダイヤモンドは,下層マントルの条件下で玄武岩結晶化を明らかにし,このマントルのリサイクルプロセスを確認しています.
科学分野:
- 地質学 地質学 地質学
- ミネラロジーは,鉱物学です.
- 地質化学 地質化学
背景:
- プレートテクトニクスは,マントルに海洋地殻の沈下を誘導する.
- 地震学と地化学は,海殻が下層マントルに到達し,上層マントルに戻ることを示唆しています.
- 下層マントルの帰還の直接的な地質学的証拠は欠けています.
研究 の 目的:
- 下層マントルから沈下した海洋地殻が戻ってきたことを示す直接的な地質学的証拠を提供するためである.
- 深層の炭素循環の範囲を調査するために.
主な方法:
- ブラジル,ジュイナ5キンバーライトの超深層ダイヤモンドの分析.
- ダイヤモンド内の鉱物含有物の調査.
- ダイヤモンドの宿主の炭素同位体分析.
主要な成果:
- インクルージョンは,下層マントルの圧力と温度下でベースアルト結晶化に一致する鉱物集合を示している.
- 含有鉱物学は,下から上のマントルの発掘を示しています.
- ダイヤモンドの宿主体は,表面由来の炭素の炭素同位体シグネチャーを示しています.
結論:
- 深い炭素循環は下層マントルにまで広がっている.
- 沈下した海殻は下層マントルを通して再利用される.
- 超深層のダイヤモンドは,下層マントルのプロセスを研究するために重要なサンプルとして機能します.
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