Fore-arc migration in Cascadia and its neotectonic significance
Fore-arc migration in Cascadia and its neotectonic significance
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卡斯卡迪亚弧前迁移及其新构造意义
DOI：
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发表时间：
1998
期刊：
影响因子：
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通讯作者：
R. Blakely
中科院分区：
文献类型：
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作者：
R. Wells;C. Weaver;R. Blakely
新近纪的变形、古地磁旋转和稀疏的大地测量数据表明，卡斯卡迪亚弧前正在沿海岸向北迁移，并分裂成大型旋转地块。变形主要发生在俄勒冈州一个相对抗震的大型沿海地块的边缘，该地块由厚厚的海山地壳组成。这个400公里长的地块相对于北美在华盛顿东部的欧拉极点附近缓慢顺时针移动，从而在布兰科角附近的前缘增加了汇聚速度，并在其后缘形成了一个伸展的火山弧。该地块向北移动，将华盛顿州西部划分为较小的地震活跃地块，并将它们挤压到加拿大海岸山脉的限制弯曲处。弧前地块的弧线平行运移计算为9毫米/年，足以在沿地块边缘的大变形带内产生破坏性地震。
Neogene deformation, paleomagnetic rotations, and sparse geodetic data suggest the Cascadia fore arc is migrating northward along the coast and breaking up into large rotating blocks. Deformation occurs mostly around the margins of a large, relatively aseismic Oregon coastal block composed of thick, accreted seamount crust. This 400-km-long block is moving slowly clockwise with respect to North America about a Euler pole in eastern Washington, thus increasing convergence rates along its leading edge near Cape Blanco, and creating an extensional volcanic arc on its trailing edge. Northward movement of the block breaks western Washington into smaller, seismically active blocks and compresses them against the Canadian Coast Mountains restraining bend. Arc-parallel transport of fore-arc blocks is calculated to be up to 9 mm/yr, sufficient to produce damaging earthquakes in a broad deformation zone along block margins.