对比地的生产和地幔的快速过渡在后方弧形山脊下
Robert A Dunn1, Fernando Martinez
1Department of Geology and Geophysics, University of Hawaii, Honolulu, Hawaii 96822, USA. dunn@soest.hawaii.edu
Nature
|January 14, 2011
概括
后弧流域的扩散揭示了海底地性质的突然变化,挑战了逐渐进化的模型. 这表明了潜水带附近的地幔上升的动态过程.
科学领域:
- 地质地质地质地质地质地
- 地质物理学 地质物理学
- 构造学 构造学 构造学 构造学
背景情况:
- 背弧盆地通过裂和海底扩张在俯冲区后面形成.
- 扩散的山脊上的岩预计会随着它们远离俯冲的影响而逐渐变化.
- 现有的模型预测沿着蔓延的山脊逐渐改变地的特性.
研究的目的:
- 为了调查东部传播中心地物质变化的性质.
- 为了确定地性质的变化是否随着山脊从火山弧移动而逐渐或突然发生.
主要方法:
- 对海底形态学的分析.
- 测量上层地的地震速度.
- 解释重力异常和静止状态的解释.
主要成果:
- 观察到海底形态的突然变化,地震速度 (增加20%以上),地厚度 (稀薄超过1.9公里).
- 这些变化发生在山脊轴与火山前线的最小分离 (仅为5公里) 时.
- 在地性质的横冲击和沿冲击变化是显著的和突然的.
结论:
- 这些发现与预测渐进地演变的模型相矛盾.
- 突如其来的变化暗示了被拖走的地幔的快速演变,一个动态的上游区域捕获,然后释放富含水的地幔.
- 这种动态过程挑战了稳定,宽广的三角形上游区域的形成,这与地幔角附近的中洋山脊典型.
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