在加利福尼亚州的内华达山脉南部下方,大陆弧根的活跃沉降
George Zandt1, Hersh Gilbert, Thomas J Owens
1Department of Geosciences, University of Arizona, Tucson, Arizona 85721, USA. zandt@geo.arizona.edu
Nature
|September 3, 2004
概括
塞拉内华达山脉的密集根源正在被地幔滴水移除,导致地的加厚和沉降. 这种由粘性合驱动的过程重塑了加利福尼亚山脉.
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
- 地力学是什么?地力学是什么?
背景情况:
- 了解地-地幔相互作用对于理解山脉演变至关重要.
- 南部的塞拉内华达山脉为研究这些过程提供了一个独特的自然实验室.
研究的目的:
- 为了调查正在进行的塞拉内华达山脉低岩石根的移除.
- 分析地-地幔相互作用及其表面效应的地震成像.
主要方法:
- 对地震数据的分析,以图像地表结构和过程.
- 解释地质数据以了解地和地幔动态.
主要成果:
- 地震数据显示,塞拉内华达山脉密集根的移除始于1000万至300万年前,通过雷利-泰勒不稳定.
- 一个几乎水平的剪切区域分离了超岩根;粘性阻力使西部侧面的地变厚7公里.
- 一个V形的地圆被拖入地幔滴水中,导致Moho在地震图像中消失,并导致表面沉降.
结论:
- 塞拉内华达山脉石根的去除是一个活跃的地力学过程.
- 地和地幔之间的粘性合是当前该地区地表沉降的主要驱动因素.
- 地震成像为大陆山脉的动态演变提供了关键的见解.
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