Constraints on residual topography and crustal properties in the western United States from virtual deep seismic sounding
Constraints on residual topography and crustal properties in the western United States from virtual deep seismic sounding
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DOI：
10.1002/2016jb013046
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发表时间：
2016-08
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通讯作者：
Chunquan Yu;Wang-Ping Chen;R. Hilst
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作者：
Chunquan Yu;Wang-Ping Chen;R. Hilst
我们使用虚拟深地震测深（VDSS）和来自约1000个宽带地震台站的数据，以提供美国西部科迪勒拉（美国）地壳结构的高分辨率估计。最可靠的结果是残余地形的地理分布（即观测到的海拔高度与仅从地壳浮力预测的海拔高度之间的差异），以及地幔中的热异常或岩石异常。总的来说，美国西部科迪勒拉山脉的残留地形变化很大;在200 km或更短的距离内，对比度高达约3 km。沿科罗拉多高原和大盆地周围的沿着，残留地形高，表明地幔效应大。相比之下，中央科罗拉多高原和怀俄明州盆地显示低残留地形，接近预期的地质稳定的岩石圈。总的来说，在瓦萨奇铰线（在北美海盆基底的显著延伸的东部界限）以东的地区，上地幔中高残留地形和低地震波速度异常的模式是相似的，这表明一个共同的热成因。相反，这种相似性是不存在的区域以西的铰链线，这表明岩石学的地幔不均匀性的实质性影响。最后，联合分析的VDSS和常规接收器功能揭示了一个广泛的地壳P波速度，当地高达6.7公里/秒，也许表明地壳的岩浆修改。
We use virtual deep seismic sounding (VDSS) and data from ~1000 broadband seismic stations to provide high‐resolution estimates of crustal structure in the western Cordillera of the United States (U.S.). The most robust result is the geographic distribution of residual topography (that is, the difference between observed elevation and that expected from crustal buoyancy alone) and, by implication, thermal or petrologic anomalies in the mantle. Overall, residual topography of the western U.S. Cordillera varies considerably; with contrasts of up to about 3 km across distances of 200 km or less. High residual topography, indicating large mantle effects, is evident along the periphery of the Colorado Plateau and the surroundings of the Great Basin. In contrast, the central Colorado Plateau and the Wyoming Basin show low residual topography, close to what is expected of a geologically stable lithosphere. Overall, in regions to the east of the Wasatch hinge line (the eastern limit of significant extension in the North American cratonic basement) patterns of high residual topography and anomalies of low seismic wave speeds in the upper mantle are similar, suggestive of a common, thermal origin. In contrast, such a similarity is absent in regions to the west of the hinge line, suggesting substantial effects of petrological heterogeneities in the mantle. Finally, joint analyses of VDSS and conventional receiver functions reveal a wide range of crustal P wave speeds, locally as high as 6.7 km/s, perhaps indicating magmatic modification of the crust.