在赤道中大西洋山脊下面的一个薄薄的地幔过渡区
Matthew R Agius1,2, Catherine A Rychert3, Nicholas Harmon3
1Ocean and Earth Science, University of Southampton, Southampton, UK. matthew.agius@soton.ac.uk.
Nature
|January 28, 2021
概括
海洋中部的山脊促进了地球上层和下层地幔之间的物质转移,挑战了以前的假设. 这一发现表明整个地幔的对流比以前理解的更为重要,山脊起着关键作用.
科学领域:
- 地质学
- 地震学
- 地球科学
背景情况:
- 地球地幔层之间的物质转移对它的进化至关重要.
- 岩石沉积和地幔羽毛是已知的转移地点,但中海山脊不被认为是重要的.
- 在中海山脊上进行直接测量是困难的.
研究的目的:
- 研究海洋中山脊在地幔物质转移中的作用.
- 在中大西洋山脊下边界的地幔过渡区的地震断层.
- 评估整个地幔对流的影响.
主要方法:
- 使用接收器功能来转换地震波.
- 分析了来自赤道中大西洋山脊的海底地震数据.
- 在410公里和660公里深处解释地震不连续性.
主要成果:
- 观察到660公里的不连续性升高和410公里的不连续性低落,表明地幔过渡区变薄.
- 巧合缓慢的剪切波速度表明上升物质.
- 与旧的海底相比, 中大西洋山脊下的地震速度较慢.
结论:
- 中洋山脊是地幔物质从下层转移到上层的地点.
- 这种转移可能是连续的或间歇性的.
- 的上升有助于整个地幔的对流,可能会平衡板块的下降.
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