Evidence for distributed clockwise rotation of the crust in the northwestern United States from fault geometries and focal mechanisms
Evidence for distributed clockwise rotation of the crust in the northwestern United States from fault geometries and focal mechanisms
复制标题
从断层几何形状和震源机制来看美国西北部地壳分布顺时针旋转的证据
DOI：
10.1002/2016tc004223
复制
发表时间：
2017
期刊：
影响因子：
4.2
通讯作者：
C. Weaver
中科院分区：
文献类型：
--
作者：
T. Brocher;R. Wells;A. Lamb;C. Weaver
古地磁和GPS数据表明，华盛顿和俄勒冈州在过去的1600万年里一直顺时针旋转。晚新生代和第四纪断层几何形状、地震活动线性构造和震源机制提供的证据表明，这种旋转是由华盛顿的北向逆冲断层和右行走滑断层以及东部的SW至W向正断层和右行走滑断层调节的。华盛顿和西北俄勒冈州的几个曲线形NW至NNW走向的高角度走滑断层和地震活动线性构造确定了相对于北美旋转的地质极（117.7°W，47.9°N）。美国西北部和不列颠哥伦比亚省西南部的许多断层和震源机制的方向与该地质极点一致，GPS表面速度也与弹性卡斯卡迪亚俯冲带耦合校正一致。向地质极点呈放射状的大型第四纪正断层分布广泛，似乎是通过地壳伸展来适应地壳旋转，可以在沿着蒙大拿州的刘易斯和克拉克带、爱达荷州和蒙大拿州斯内克河平原以北的百年断层系统内、犹他州瓦萨奇前缘以西以及俄勒冈州和内华达州的北方盆地和山脉内找到。分布的走滑断层在华盛顿西部和俄勒冈州最为突出，并可能在整个美国西北部的断层之间传递滑动。
Paleomagnetic and GPS data indicate that Washington and Oregon have rotated clockwise for the past 16 Myr. Late Cenozoic and Quaternary fault geometries, seismicity lineaments, and focal mechanisms provide evidence that this rotation is accommodated by north directed thrusting and right‐lateral strike‐slip faulting in Washington, and SW to W directed normal faulting and right‐lateral strike‐slip faulting to the east. Several curvilinear NW to NNW trending high‐angle strike‐slip faults and seismicity lineaments in Washington and NW Oregon define a geologic pole (117.7°W, 47.9°N) of rotation relative to North America. Many faults and focal mechanisms throughout northwestern U.S. and southwestern British Columbia have orientations consistent with this geologic pole as do GPS surface velocities corrected for elastic Cascadia subduction zone coupling. Large Quaternary normal faults radial to the geologic pole, which appear to accommodate crustal rotation via crustal extension, are widespread and can be found along the Lewis and Clark zone in Montana, within the Centennial fault system north of the Snake River Plain in Idaho and Montana, to the west of the Wasatch Front in Utah, and within the northern Basin and Range in Oregon and Nevada. Distributed strike‐slip faults are most prominent in western Washington and Oregon and may serve to transfer slip between faults throughout the northwestern U.S.