地球内核的纹理由麦克斯韦强调地球内核的纹理
1Department of Earth & Ocean Sciences, University of British Columbia, Vancouver, V6T 1Z4 Canada. buffett@geop.ubc.ca
Nature
|September 7, 2001
概括
电磁应力可能解释地球内核的异质性. 模拟显示这些应力导致铁晶的对齐,与地震观测相匹配,并建议内部核心纹理发展的新机制.
科学领域:
- 地质物理学 地质物理学
- 固体地球地质物理学 地质物理学
- 矿物物理 矿物物理
背景情况:
- 地球的内核表现出弹性异构,可能是由于偏好的格子方向.
- 固化纹理本身不能解释深度依赖的异质性.
- 之前的涉及辐射流的模型受到热和化学分层的限制.
研究的目的:
- 通过电磁 (马克斯韦尔) 剪切应力驱动的塑性变形来研究内核异构的发展.
- 探索多晶可塑性和再结晶在纹理发展中的作用.
主要方法:
- 在代表性磁场条件下使用epsilon-iron的多晶可塑性模拟.
- 模型变形适应基底和镜滑动.
- 在模拟的方向分布上平均化单晶弹性特性.
主要成果:
- 模拟显示,epsilon-iron c轴与赤道平面平行的偏好对齐.
- 当变形与再结晶相结合时,这种对齐模式得到增强.
- 由此产生的弹性异构性模式与地震学观测结果非常相符.
结论:
- 电磁切割应力提供了一个可行的机制来产生内核异性质.
- 这种机制克服了依赖辐射流的先前模型的局限性.
- 这些发现为地球内核结构的形成和演变提供了新的视角.
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