Seismic Tomography and Velocity Structure in the Crust and Upper Mantle Around Bohai Sea Area
Seismic Tomography and Velocity Structure in the Crust and Upper Mantle Around Bohai Sea Area
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DOI：
10.1002/cjg2.884
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发表时间：
2006-05
期刊：
影响因子：
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通讯作者：
Zhiwei Li;Yi Xu;T. Hao;Jin‐Song Liu;Ling Zhang
中科院分区：
文献类型：
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作者：
Zhiwei Li;Yi Xu;T. Hao;Jin‐Song Liu;Ling Zhang
通过对近震和远震P波到达时间的层析反演，重建了渤海及邻区地壳和上地幔的三维P波速度图像，其经纬向网格间距均为0.5°×0.6°。速度图像显示环渤海地区地壳和上地幔具有明显的横向非均质性。中上地壳速度异常反映了地表地质特征：造山带和隆起区速度较高，凹陷和沉积盆地速度较低，中国北段中下地壳广泛分布的低速与本区高导层相对应，可能是部分熔融和岩浆活动所致。莫霍面附近的速度异常反映了地壳厚度的变化和壳幔边界的热状态，而上地幔的低速异常可能与软流圈热物质的上涌有关。
Three-dimensional P wave velocity images of the crust and upper mantle beneath Bohai Sea and its adjacent regions are reconstructed through a tomographic inversion of P wave arrival times from local and teleearthquakes, with a grid spacing of 0.5° × 0.6° in latitude and longitude directions. The velocity images reveal an evident lateral heterogeneity of the curst and upper mantle around Bohai sea area. Velocity anomalies in upper-mid crust reflect the characters of surface geology: orogenic belt and uplift areas have high velocities, while depressions and sedimentary basins have low velocities; widely-distributed low velocities in the mid-lower crust beneath North China correspond to high conductive layers in this region, which may be caused by partial-melting and magma activity. Velocity anomalies near Moho reflect the variation of crust thickness and the thermal state in crust-mantle boundary, while low velocity anomalies in uppermost mantle may be related with the upwelling of hot materials from asthenosphere.