科研之友
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摘要
The Bohai Strait is an important channel to link the Liaodong peninsula and the Shandong peninsula of eastern China. To estimate the stability of the crustal structure of the strait and adjacent areas, we used seismic tomography to construct a three-dimensional P-wave velocity model for this region. Distinct velocity variations are observed beneath the Bohai Strait. Its northern part is featured by a high-velocity curst with stable structure, less affected by tectonic alternations, with weak seismicity. However, a thin low-velocity layer is found in the lowermost crust, which extends from the northern strait toward the Liaodong peninsula, and may be a detachment layer between the crust and the upper mantle. We need to confirm this layer through future studies. On the contrary, the southern part of the strait is featured by a low velocity crust with active seismicity likely associated with the Zhangjiakou-Penglai fault zone. Tectonic activity along this fault zone greatly affects the stability of the crustal structure of the southern strait. In the southern Bohai Sea, prominent velocity variations are observed in the east and west of the Tan-Lu fault zone. Compared to the high-velocity crust in the west, the east of the fault zone adjacent to the Bohai Strait is featured by the low-velocity crust. This is probably related to a broadly distributed fault system and frequent earthquakes of the area. Additionally, affected by the North China Craton destruction and mantle upwelling, low velocity characterizes the deep crust and upper mantle of the Bohai Sea. Evidence of heat flows can be found in the uppermost mantle beneath the Tan-Lu fault zone and the Bohai Strait, which reflects the thinning of the lithosphere and the local rise of the asthenosphere.
- 出版日期2017-1
- 单位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; 防灾科技学院; 中国科学院地质与地球物理研究所; 中国科学院大学
