プレッシャーによる無形化は,石層のマントルの変形を引き起こします
Vahid Samae1, Patrick Cordier2,3, Sylvie Demouchy4
1Electron Microscopy for Materials Science, University of Antwerp, Antwerp, Belgium.
Nature
|March 4, 2021
まとめ
オリビンに富んだ岩は,ストレス下での粒子の境界の無形化によって変形し,柔らかさを可能にします. このメカニズムは,地球上のプラスチックの流れを説明します
科学分野:
- 地理学
- 材料科学
- 鉱物物理学
背景:
- オリヴィンに富んだ岩石の機械的性質は,石層とアステノスフィアの結合を理解するために不可欠です.
- 結晶欠陥の動きは結晶材料のプラスチック流動を制御しますが,オリビンは限られた滑りシステムのために追加の変形メカニズムを必要とします.
- 粒子の境界の滑り方はオリビンの変形のための提案されたメカニズムですが,その微細構造的基礎と理論的統合は不明です.
研究 の 目的:
- オリビンに富んだ岩石の粒子の境界における変形メカニズムを特定し,特徴づけること.
- 多結晶の可塑性モデルに粒子の境界メカニズムを組み込むための理論的枠組みを提供する.
- オリヴィンに富んだ材料の 柔らかさとプラスチック流出の始まりを説明するために
主な方法:
- ストレス下でのフォルステライト (オリビンに富んだ鉱物) の実験調査.
- 粒子の境界を中心とした微細構造分析
- 多結晶の可塑性を理論的にモデル化する.
主要な成果:
- ストレス下でのフォースタライトの粒子の境界で無形化が発生します.
- 粒子の境界に無形な層が形成され,粒子の境界の移動性が活性化され,柔らかさが生じます.
- このメカニズムは,オリヴィンがガラスの移行温度に近づくリトスフィア-アステノスフィアの境界で特に重要です.
結論:
- 粒子の境界におけるストレス誘発型無形化の新しいメカニズムは,オリビンに富んだ岩石の伸縮性を支配する.
- このプロセスは,特に脆いプラスチック移行と石層-アステノスフィアの境界で,地球深層のプラスチック流動を容易にします.
- この発見は,大規模な地質学的変形を理解するための新しい理論的基礎を提供します.
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