Northwest Basin and Range tectonic deformation observed with the Global Positioning System, 1999–2003
Northwest Basin and Range tectonic deformation observed with the Global Positioning System, 1999–2003
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DOI：
10.1029/2005jb003678
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发表时间：
2005-10
影响因子：
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通讯作者：
W. Hammond;W. Thatcher
中科院分区：
文献类型：
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作者：
W. Hammond;W. Thatcher
[1]我们使用全球定位系统（GPS）获得的大地速度来量化构造变形的西北盆地和山脉省的美国西部。这些结果是基于1999年和2003年在北方内华达州、东北部加州和东南部俄勒冈州的五个新的准线性网络中收集的GPS数据。速度显示北方内华达州相对于稳定的北美洲向西移动了1.3毫米/年。在西经119°以西，速度增加并转向西北，与内华达州山脉/大峡谷微板块运动平行，与以前在南部获得的速度相似。这些观察结果可以通过一个运动学模型来解释，该模型具有围绕俄勒冈州东部和爱达荷州西部欧拉极旋转的三个域。加州东北部经历了近平行于太平洋/北美运动的内部右旋剪切变形（11.2 ± 3.6 n应变/年）。这些区域的相对运动表明，在内华达州西北部，约2-5 mm/yr的东西向伸展，在加州/俄勒冈州边界附近，约1-4 mm/yr的南北向收缩。内华达州西北部向北逐渐减小的近似东西向的伸展与盆地和山脉变形、断裂和特征地形的北方终止是一致的。在俄勒冈州盆地和山脉没有发现明显的延伸。俄勒冈州喀斯喀特弧以每年3.5毫米的速度向北移动，可能受到胡安·德富卡板块大致向东运动的影响。这些结果不同意长期西北沟向运动的俄勒冈州弧前推断从古地磁旋转。然而，在纬度43°以南，存在向沟运动，并且与块体旋转、大致东西向的盆地和山脉延伸以及内华达州山脉西北部平移相一致。
[1] We use geodetic velocities obtained with the Global Positioning System (GPS) to quantify tectonic deformation of the northwest Basin and Range province of the western United States. The results are based on GPS data collected in 1999 and 2003 across five new quasi-linear networks in northern Nevada, northeast California, and southeast Oregon. The velocities show ∼3 mm/yr westward movement of northern Nevada with respect to stable North America. West of longitude 119°W the velocities increase and turn northwest, parallel to Sierra Nevada/Great Valley microplate motion, and similar to velocities previously obtained to the south. The observations are explained by a kinematic model with three domains that rotate around Euler poles in eastern Oregon and western Idaho. Northeast California experiences internal dextral shear deformation (11.2 ± 3.6 nstrain/yr) subparallel to Pacific/North America motion. Relative motions of the domains imply 2–5 mm/yr approximately east-west extension in northwest Nevada and 1–4 mm/yr approximately north-south contraction near the California/Oregon border. The northward decreasing approximately east-west extension in northwest Nevada is consistent with the northern termination of Basin and Range deformation, faulting and characteristic topography. No significant extension is detected in the Oregon Basin and Range. The Oregon Cascade arc moves north at ∼3.5 mm/yr and is possibly influenced by the approximately eastward motion of the Juan de Fuca plate. These results disagree with secular northwest trenchward motion of the Oregon forearc inferred from paleomagnetic rotations. South of latitude 43°, however, trenchward motion exists and is consistent with block rotations, approximately east-west Basin and Range extension, and northwest Sierra Nevada translation.