科研之友
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摘要
A detailed and reliable Moho structure can improve our understanding of the tectonic evolution of crust and mantle. Most researchers directly interpolate the imaging results of receiver functions (RFs) from the sparse stations to obtain a continuous Moho image. However, the interpolation process is usually not robust because of the sparse and irregular geometry of seismic networks. In light of the approximate plane-wave feature of the teleseismic wavefront, we introduce the Radial Basis RBF) technique, a high-precision interpolator with strong adaptability, into teleseismic wavefield reconstruction. Then, we use the reconstructed wavefield to image the Moho structure beneath South China with RF analysis. Compared to the conventional H-kappa stacking methods, the Moho that is obtained through this reconstructed wavefield exhibits more details and shows greater consistency to the tectonic provinces. The Moho depths beneath South China gradually shallow from similar to 50 km at the Yangtze Block (YB) in the northwest to similar to 25 km to the southwest of the Cathaysia Block (CB). The V-p/V-s ratio at the YB is similar to 1.80 , decreasing to similar to 1.57 at the Jiangnan Orogen, and then increasing to similar to 1.70 at the CB. Obviously varying Moho depths and V-p/V-s ratios in both the Ganjiang Fault (GF) and Tancheng-Lujiang Fault (TLF) regions is observed, which indicates a great similarity in the deep tectonic environment of the GF and TLF. The mantle corner flow under South China is suspected to invade into the interior of the Yangtze Craton. Teleseismic wavefield reconstruction, as a pre-processing technique, can effectively improve the imaging quality of RF analysis.
- 出版日期2017-10-30
- 单位中国地震台网中心; 中国科学院地质与地球物理研究所兰州油气资源研究中心; 中国地震局; 中国科学院大学; 中国科学院地质与地球物理研究所
