Analysis of converted shear-waves based on OBS data in the South Yellow Sea and its geological implications

作者：Zhao Wei-Na; Zhang Xun-Hua; Meng Xiang-Jun; Wu Zhi-Qiang^*; Qi Jiang-Hao; Hao Tian-Yao; Zheng Yon-Peng

来源：Acta Geophysica Sinica, 2017, 60(4): 1479-1490.

DOI：10.6038/cjg20170421

• OBS
• Converted S-wave
• South Yellow Sea
• V-P/V-S

Multi-component seismic exploration can reduce the multi-solutions of geophysical inversion. Meanwhile it is able to reveal more abundant underground information. Multi component seismic exploration can realize lithologic exploration from a quantitative perspective. S-waves are rarely involved in the study of crust structure in the South Yellow Sea (SYS) for the complexity of the crust structure and the particularity of converted shear waves. With analysis of travel time of OBS data from SYS, this work did ray tracing and fitting to apparent velocity and particle trajectory between P-component and inline component, the transformation phases from crust and sediments based on the known P-wave velocity model. The results show that only PPS mode, whose surface is the continental deposit bottom interface, appears in the North Depression (ND) of the SYS. Both PPS mode and PSS modes are present in the Qianliyan Uplift (QU) and have significant differences in velocity. High V-p/V-s ratios caused by rock breaking as a result of the fault activity are another piece of evidence regarding to the boundary of the Jiaolai Basin in the SYS. The high velocity layer in the QU mainly comprise metamorphic granite with probable rich silicon, whose ratios range from 1.67 similar to 1.68. The V-p/V-s ratios of the marine sedimentary layer display the characteristics of carbonate rock in the ND. However, the sediment beneath the continental deposit layer is most likely composed of sandstone in the southeast of the ND.

• 出版日期2017-4
• 单位中国海洋大学; 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; 青岛海洋地质研究所; 中国科学院地质与地球物理研究所; 国家海洋局第一海洋研究所