概括
地震波速异形学揭示了海洋地幔的变形是由海底的扩散和天体流动主导的,而不是板块的运动. 这说明了海洋底下塑造地球内部的过程.
科学领域:
- 地质学
- 地震学
- 构造学
背景情况:
- 构造板块的运动和地幔的对流使地球的内部变形,通过地震波速异性质可检测的岩石结构.
- 海洋上层地幔的变形通常推断在岩层边界附近,特别是在海底扩散中心和天气层内.
- 地震模型对海底扩散与大气层流动在海洋岩层变形中的相对重要性提出了不同的观点.
研究的目的:
- 通过使用海底地震仪数据,研究太平洋中部的海洋岩层-岩层系统中的地震异构性.
- 在海洋板块中间对变形过程提供局部约束.
- 区分海底扩散,层流动和板块运动作为地幔变形的驱动因素.
主要方法:
- 通过NoMelt实验的海底地震仪阵列记录的雷利波分析.
- 在海洋石化层和石化层中绘制地震异性变异,特别是亚齐木特异性变异.
- 快速地震波的方向与海底扩散方向和板块运动进行比较.
主要成果:
- 在高地震速度的盖子中,亚齐木特异性最强,与海底的扩散方向保持一致.
- 在中部地震低速度区域的异位变化幅度最低,而在天气层下面的深度增加.
- 快速的地震方向与任何深度的板块运动无关.
结论:
- 浅层海洋地幔的主要变形发生在轴角流和压力/浮力驱动的天气流中.
- 与其他变形机制相比,板块在天气层上的运动造成的剪切变形似乎是一个小的过程.
- 地震异形学提供了海洋石化层-石化层系统中复杂的变形过程的关键见解.
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