一个颠倒的大陆Moho和前弓地幔的蛇形化
M G Bostock1, R D Hyndman, S Rondenay
1Department of Earth and Ocean Sciences, The University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada. bostock@geop.ubc.ca
Nature
|May 31, 2002
概括
沉降板块释放挥发性物质,导致融化和火山活动. 在卡斯卡迪亚潜伏区,地震学揭示了一个水化,蛇形化的前弧地幔,影响地震破裂极限.
科学领域:
- 地质物理学 地质物理学
- 地震学 地震学
- 构造学 构造学 构造学 构造学
背景情况:
- 引板运输挥发物质,诱导地幔融和弧形岩.
- 前弧地幔通常被认为比后弧区域更冷,这是由于天气层流动.
- 了解地幔形结构对于解释弧形岩和地震危害至关重要.
研究的目的:
- 为了研究南卡斯卡迪亚沉降区的地幔形结构.
- 为了确定前弓地幔的物理状态和组成.
- 评估前弧地幔特性对地震性和地幔流动的影响.
主要方法:
- 对分散的远震波进行分析.
- 部署一个密集的便携式宽带地震计阵列.
- 解释地震速度和莫霍结构.
主要成果:
- 在寒冷前弧地幔中发现了非常低的剪切波速度.
- 发现了一个异常的"倒置"的大陆莫霍结构.
- 有证据表明,前弓地幔区域高度水化和蛇形化.
结论:
- 南卡斯卡迪亚的前弓地幔形显著地受水和蛇形化.
- 这种蛇形化与潜水区的热和岩石模型相一致.
- 蛇形化材料的低强度可能控制地震破裂极限和地幔流动力学.
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