Rayleigh-wave Tomography Based on Ambient Seismic Noise in the Central and Western Blocks of the North China Craton
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摘要: 根据2011年在鄂尔多斯地区新架的51套宽频带流动地震台数据,结合区域数字地震台网138个固定台站和2007年华北流动地震台阵连续一年的地震记录,基于背景噪声成像的基本原理与方法得到了华北克拉通中西部地区6~36 s的瑞利面波群速度分布图像。6~15s的成像结果很好地对应于上地壳的隆起和塌陷盆地构造;16~30 s的成像结果揭示了大同盆地和汾河谷地西侧可能存在中下地壳低速层;30~36 s的成像结果反映了华北克拉通地壳东薄西厚的总格局,和断陷盆地下方莫霍面相对隆起的局部特征。Abstract: Using the one-year ambient noise records of 51 portable broadband stations across the Ordos Block and 138 permanent stations from May 2010 to April 2011 with data of the North China Array during the year of 2007,we obtained Rayleigh wave group velocity maps in the Central and Western Blocks of the North China Craton from 6s to 36s based on ambient seismic noise tomography.The results for 6s to 15s show the outline of tectonic units in the upper crust,such as rises and collapse basins;the results for 16s to 30s indicate the possibility of low-velocity zones within the middle and low crust of the Datong Basin and the western area of the Fenhe Basin;the results for 30 s to 36 s show that the thickness of the crust in the Eastern Block is thinner than that in the Central and Western Blocks,and the Moho depth of some collapse basins is respectively shallower compared with that of adjacent regions.
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Keywords:
- North China Craton /
- Ordos /
- ambient noise tomography /
- Rayleigh wave /
- group velocity
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