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OBS2013测线沿NNW-SSE方向跨越渤中坳陷和胶东隆起次级构造以及张家口-蓬莱和郯庐两条深大断裂带.对测线上13个站位折合剖面进行震相分析,识别出丰富的Ps、Pg、PcP、Pn和PmP震相.通过射线追踪和走时拟合,建立了二维P波速度结构模型.模型将渤海深部速度结构分为6层,最上部两层为新生界,速度由1.8~2.0km/s变化为4.4~4.7km/s,埋深为0.5~7.2km,并向胶东隆起方向逐渐尖灭.向下依次分为上地壳下部、中地壳和下部地壳,地壳速度由5.6~5.9km/s变化为7.0km/s,其中上地壳底界面埋深11.1~12.9km,中地壳底界面埋深18.0~18.9km,莫霍面在渤中凹陷处埋深最浅为25.5km,向胶东隆起方向逐渐增大到30km.莫霍面之下上地幔顶部速度为8.0~8.1km/s.渤海下部地壳厚度变化接近5km,从下地壳到上地幔顶部均无明显的大尺度横向速度变化,岩浆底侵不发育.结合已有研究成果,推测渤海东南部与华北克拉通中部相比,下地壳厚度减薄9~13.4km,地壳减薄非常有限,具有典型陆壳特征.
The OBS2013 line crosses over the Bozhong Depression and the Jiaodong Uplift secondary structure along the NNW-SSE direction and two deep faults such as Zhangjiakou-Penglai and Tanlu Faults. The seismic phase analysis of the 13 stations at the measured line reveals that Rich Ps, Pg, PcP, Pn and PmP phases.A two-dimensional P wave velocity structure model is established by ray tracing and traveltime fitting.The model divides the deep velocity structure of Bohai Sea into 6 layers and the uppermost two layers are Cenozoic , The velocity changes from 1.8 ~ 2.0km / s to 4.4 ~ 4.7km / s and the depth is 0.5 ~ 7.2km, and gradually decreases to the east of Jiaodong uplift.They are divided into lower upper crust, middle crust and lower crust, The crustal velocity changed from 5.6km / s to 5.9km / s to 7.0km / s, in which the depth of the upper crust bottom interface was 11.1-12.9km, that of the middle crust bottom interface was 18.0-18.9km, and that of the Moho was the highest in the middle Bozhong depression Shallow 25.5km, and gradually increased to 30km in the direction of Jiaodong uplift.The top velocity of the upper mantle beneath the Moho is 8.0 ~ 8.1km / s.The thickness of the lower crust in the Bohai Sea changes nearly 5km, and there is no significant difference from the lower crust to the top of the upper mantle Of large-scale lateral velocity changes, the magma underdevelopment is not developed.Combining the existing research results, it is speculated that the southeastern Bohai and North China craton Ratio, the thinner the thickness of the crust 9 ~ 13.4km, crustal thinning is very limited, with the typical characteristic crust.