アケア紀の地殻の進化は,デラミネーションと浅い潜水によるものでした
Stephen F Foley1, Stephan Buhre, Dorrit E Jacob
1Institut für Geologische Wissenschaften, Universität Greifswald, Germany. sfoley@uni-greifswald.de
Nature
|January 17, 2003
まとめ
初期の地球 初期の地球
科学分野:
- 地質科学は地質科学である.
- ペトロロジー・ペトロロジーとは
- テクトニクス (地質学) とは
背景:
- 古代の海洋の地殻は,より高い熱流量により,現代の地殻よりも厚く,よりマグネシウムが豊富だった可能性が高い.
- 以前の潜水実験では,初期の地球条件を無視して,現代の海中の玄武岩のみを使用していました.
研究 の 目的:
- サブドクション中の初期のアーカイアン時代の海洋地殻の変形反応を調査する.
- 地殻のリサイクルと大陸地殻の形成への影響を理解する.
主な方法:
- 高圧実験ペトロロジー.
- ウルトラマフィカル・カミュレートとピクリートからの変形反応産物の分析.
主要な成果:
- 初期のアルカイア期の地殻材料の変形により,ピロクセニトが産生され,それらはデラミネートされ,玄武岩に溶け込みます.
- 大陸地殻の形成には,ガーネット・アンフィボライトの沈殿と融解が必要で,これはアルカイアン後期以降に流行していた.
- 初期のアーケア紀の浅い沈殿は,薄い上部マントルの層のみを枯渇させた.
結論:
- 初期のアルカイア期には地殻の沈下が浅かったため,マントルの枯渇が限られていた.
- 枯渇したマントル層の絶え間ない深化が,地化学モデルと地物理モデルとの不一致を説明している.
- 大陸地殻の形成は,より深い潜水過程でアーカイアン後期に顕著に始まった.
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