在地幔条件下,佩里克拉斯的变形速度比布里格曼石慢
Patrick Cordier1,2, Karine Gouriet3, Timmo Weidner3
1Univ. Lille, CNRS, INRAE, Centrale Lille, UMR 8207 - UMET - Unité Matériaux et Transformations, Lille, France. patrick.cordier@univ-lille.fr.
Nature
|January 11, 2023
概括
在高压下,由于氧气扩散缓慢,下层层围变形非常缓慢. 这表明布里格曼,而不是铁烯酸,主导了下层地幔的气质,影响了我们对地幔对流的理解.
科学领域:
- 地质学
- 矿物物理
- 材料科学
背景情况:
- 地幔对流是由地球的内部热传输驱动的,在地质时间尺度上导致固体岩石变形.
- 下层地幔包括含铁的桥和铁烯酸,而铁烯酸传统上被认为是较弱的.
- 实验室研究在复制与地质过程相关的自然极低应变率方面存在局限性.
研究的目的:
- 在下层地幔条件下研究变形机制和质性质.
- 在高压和高温下模拟MgO环氧化物的缓慢爬行,使用脱位动力学.
- 为了确定环对下层地幔组合的整体体质的贡献.
主要方法:
- 使用2.5维脱位动力学模拟.
- 在模拟的下层地幔压力和温度下模拟的MgO环氧化物的低应力爬行.
- 通过纯爬变形与桥形变形的比较.
主要成果:
- 在较低的地幔条件下,佩里克拉斯表现出极其缓慢的变形速度,比布里格曼石要慢得多.
- 在压力下缓慢的氧气扩散被确定为其变形率降低的主要原因.
- 铁烯酸酶在变形中的有限参与意味着布里格曼石的形学控制了下层的整体行为.
结论:
- 下层地幔的质主要由桥石控制,这挑战了关于铁烯酸酶作用的先前假设.
- 矿物质的变形机制可以随着变化的应变率而发生剧烈变化,这凸显了多尺度建模的重要性.
- 这些发现为地幔对流动力学和地球内部的长期演变提供了关键的见解.
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