橄晶格的自然例子首选的定向模式,流量正常的a轴最大值
Tomoyuki Mizukami1, Simon R Wallis, Junji Yamamoto
1Department of Geology and Mineralogy, University of Kyoto, Sakyo-ku, Kyoto, 606-8501, Japan. mizukami@kueps.kyoto-u.ac.jp
Nature
|January 30, 2004
概括
构造板块运动会影响地幔流动和地震波速度. 这项研究揭示了日本广泛的B型橄 orientation,暗示了比以前想象的更简单的俯冲区地幔流动模式.
科学领域:
- 地质物理学 地质物理学
- 矿物物理 矿物物理
- 构造学 构造学 构造学 构造学
背景情况:
- 构造板块的运动驱动了上层地幔的流动,导致了橄晶体的方向和机械异质性.
- 这种异构性通常将地震波速度与板块运动平行对齐,由olivine'a-axis'对齐解释.
- 俯冲区是一个难题,推断的橄石"a轴"垂直于板块运动,通常归因于复杂的地幔流动.
研究的目的:
- 为了研究橄石在潜水带中形成的偏好方向.
- 探索水在影响橄晶体对齐中的作用.
- 重新评估地幔流在俯冲区的模型.
主要方法:
- 在日本西南部的一种潜水式变态带的地质实地研究.
- 使用石岩和结晶学技术分析橄石的偏好方向模式.
- 评价水含量及其与观察到的橄状方位的相关性.
主要成果:
- 在日本的变形带中记录了广泛的B型橄石偏好方向模式.
- 这些B型模式,以"a轴"最大垂直于流量为特征,被发现是在水的存在下发展的.
- 这些发现挑战了潜伏区高度复杂的地幔流的概念.
结论:
- 水的存在可以导致B型橄素的形成.
- 在日本观察到的B型橄树的图案表明,地幔在俯冲区上方的流动可能比以前假设的更简单.
- 这对理解地幔动力学和在俯冲环境中的地震异型性有重大意义.
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