Sedimentary and crustal thicknesses and Poisson's ratios for the NE Tibetan Plateau and its adjacent regions based on dense seismic arrays
Sedimentary and crustal thicknesses and Poisson's ratios for the NE Tibetan Plateau and its adjacent regions based on dense seismic arrays
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DOI：
10.1016/j.epsl.2016.12.040
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发表时间：
2017-03
影响因子：
5.3
通讯作者：
Weilai Wang;Jianping Wu;L. Fang;Guijuan Lai;Y. Cai
中科院分区：
文献类型：
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作者：
Weilai Wang;Jianping Wu;L. Fang;Guijuan Lai;Y. Cai
利用1,317个台站的接收函数的h-κ叠加和CCP图像，估算了青藏高原东北部及邻区的沉积厚度、地壳厚度和泊松比。所获得的结果水平分辨率高达0.5°× 0.5°，可用于该地区进一步的高分辨率模式建设。四川盆地、祁连构造带、北方阿拉善地块和柴达木盆地的地壳厚度小于艾里平衡结果，这与地幔岩石圈的高密度相一致，可能表明高密度岩石圈对地壳的整体拉低作用。在东祁连构造带的中下地壳和鄂尔多斯地块边界地区存在高泊松比和低速带，表明这些地区可能存在部分熔融作用。青藏高原东北部地壳存在低泊松比和低速异常，表明该地区镁铁质下地壳减薄或缺失，中、下地壳未发生熔融或部分熔融，不可能存在弱流动层。
The sedimentary and crustal thicknesses and Poisson's ratios of the NE Tibetan Plateau and its adjacent regions are estimated by the h–κ stacking and CCP image of receiver functions from the data of 1,317 stations. The horizontal resolution of the obtained results is as high as 0.5°× 0.5°, which can be used for further high resolution model construction in the region. The crustal thicknesses from Airy's equilibrium are smaller than our results in the Sichuan Basin, Qilian tectonic belt, northern Alxa block and Qaidam Basin, which is consistent with the high densities in the mantle lithosphere and may indicate that the high-density lithosphere drags crust down overall. High Poisson's ratios and low velocity zones are found in the mid-and lower crust beneath eastern Qilian tectonic belt and the boundary areas of the Ordos block, indicating that partial melting may exist in these regions. Low Poisson's ratios and low-velocity anomalies are observed in the crust in the NE Tibetan Plateau, implying that the mafic lower crust is thinning or missing and that the mid-and lower crust does not exhibit melting or partial melting in the NE Tibetan Plateau, and weak flow layers are not likely to exist in this region.