马里亚纳山脉和安第斯山脉潜水系统中的沟沟平行流和地震异质性
Erik A Kneller1, Peter E van Keken
1Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan 48109, USA. ekneller@umich.edu
Nature
|December 22, 2007
概括
三维地幔流动是由玛丽亚纳山和南安第斯山脉等俯冲区中复杂的板块几何驱动的,解释了观测到的地震异质性模式. 这项研究将构造板块运动与地幔动力学联系起来.
科学领域:
- 地质物理学 地质物理学
- 地震学 地震学
- 构造学 构造学 构造学 构造学
背景情况:
- 剪切波分裂揭示了俯冲区的地震异构性.
- 马里亚纳山脉和南安第斯山脉流区附近的异构性图案显示了沟附近的沟平行快速方向,以及后方弧度中的沟垂直异构性.
- 在这些系统中,板块几何学的沿冲动变化是显著的.
研究的目的:
- 为了研究板块几何和地幔中固态爬行过程之间的联系.
- 用三维俯冲区模型来解释观测到的地震异构性模式.
主要方法:
- 对剪切波分裂测量的分析.
- 开发和应用完全三维的非牛顿式俯冲区模型.
主要成果:
- 模拟强沟平行拉伸在地幔,由于板块曲率和浅沉.
- 观察到拉伸方向的急剧旋转,与地震异质性数据一致.
- 证明通过板块几何变化诱导的三维流可以解释观察到的异构性.
结论:
- 板块几何结构的沿冲动变化是潜水区下面三维地幔流动的主要驱动因素.
- 这种流动模式成功地解释了观测到的地震异质性,包括剪切波分裂测量.
- 玛丽亚纳山脉和南安第斯山脉的俯冲系统是理解这种关系的关键例子.
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