Crustal flow pattern beneath the Tibetan Plateau constrained by regional Lg-wave Q tomography
Crustal flow pattern beneath the Tibetan Plateau constrained by regional Lg-wave Q tomography
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DOI：
10.1016/j.epsl.2013.09.038
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发表时间：
2013-12
影响因子：
5.3
通讯作者：
Lian‐Feng Zhao;Xiao-Bi Xie;Jiankun He;Xiaobo Tian;Z. Yao
中科院分区：
文献类型：
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作者：
Lian‐Feng Zhao;Xiao-Bi Xie;Jiankun He;Xiaobo Tian;Z. Yao
作为一种显著的地球物理异常，青藏高原地壳和上地幔特别是北部地区的地震波衰减异常高。理论和实验室研究表明，强烈的地震衰减可以指示高温和部分熔融，这可能会降低材料的粘度，使其流动。因此，地震衰减分布可能对地壳流动提供有用的约束，如果它们存在的话。利用LG波Q层析成像技术，建立了青藏高原及周边地区0.05-10.0赫兹宽带高分辨率地壳衰减模型。在覆盖良好的地区，对于0.05~1.5赫兹的频率，最大空间分辨率约为1.0°×1.0°。这一衰减模型揭示了沿青藏高原北部和东部延伸的明显的低Q lg带。结合LG波Q模型和其他地球物理资料，在青藏高原发现了两条可能的地壳流动通道。主流道由北向东，沿刚性四川盆地西缘转向西藏东南部，第二流道始于藏南，穿越东喜马拉雅构造带。
As a prominent geophysical anomaly, unusually high seismic wave attenuation is observed in the crust and upper mantle of the Tibetan Plateau, particularly along its northern area. Theoretical and laboratory investigations show that the strong seismic attenuation can indicate high temperatures and partial melting, which may decrease the viscosity of the material and cause it to flow. Thus, seismic attenuation distribution may provide useful constraints to the crust flows if they exist. Using Lg-wave Q tomography, we construct a 0.05–10.0 Hz broadband high-resolution crust attenuation model for the Tibetan Plateau and its surrounding regions. The maximum spatial resolution is approximately 1.0°× 1.0° in well-covered areas and for frequencies between 0.05 and 1.5 Hz. This attenuation model reveals an apparent low-Q Lg belt stretching along the northern and eastern Tibetan plateau. Combining the Lg-wave Q model with other geophysical data, two possible crust flow channels are found in the Tibetan Plateau. The main flow channel is from north to east and then turns to southeastern Tibet along the western edge of the rigid Sichuan basin, while a second channel starts from southern Tibet and crosses the Eastern Himalayan syntaxis.