大陆碰撞的速度减慢是由于粘性地幔石化层而不是地形
1Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, Michigan 48109, USA. marinkc@umich.edu
Nature
|March 3, 2012
概括
板块速度是由板块边界的力驱动的. 大陆地幔石化层变形影响板块运动,显示自印度-欧亚洲碰撞以来西藏的持续应变率.
科学领域:
- 地质物理学 地质物理学
- 构造学 构造学 构造学 构造学
- 板块动力学 板块动力学
背景情况:
- 板块的速度是由边缘和底部的力量决定的,而大陆变形会影响驱动力.
- 碰撞后的板块运动速度是不太了解的,缓慢的收往往归因于地形.
- 大陆地幔岩层在板块运动中变形的作用以前没有被探索过.
研究的目的:
- 研究大陆地幔石化层变形对板块运动的影响.
- 分析印度自碰撞以来透到欧亚大陆的速度.
- 了解控制碰撞后收率的因素.
主要方法:
- 对海洋磁力异常的分析,以重建过去的板块运动.
- 构造板块力量和变形的建模.
- 考察印度-欧亚洲碰撞区的收率和应变率.
主要成果:
- 自碰撞以来,印度与欧亚的融合率呈指数级下降.
- 自碰撞以来,西藏的持续收缩应变率为7.03 × 10−16 s−1.
- 证据表明西藏下方的地幔石化层完好无损,反映了它的变形历史.
结论:
- 变形的大陆地幔石化层施加粘性阻力,影响板块运动.
- 在西藏,恒定的散装应变率意味着深度恒定的平均应力所带来的阻力.
- 地形演变并不是控制碰撞后板块运动阻力的唯一因素.
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