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以新丰江水库为中心完成了一条深地震宽角反射/折射剖面.采用动力学射线追踪方法获得了沿剖面的壳幔二维速度结构图像.结果表明:在新丰江水库东南的大坝峡谷区至河源一带,上地壳基底界面至C_1界面(上地壳上部的底面)之间速度结构存在较明显的纵横向非均匀性,速度以高、低速相间分布为特征.结合近期新丰江库区地方震精确定位结果分析发现,地震分布与这一结构异常区有较好的相关性.推测剖面120 km桩号附近可能存在至少切至上地壳上部的深部断裂.该断裂主要以水平错动为主,且在近地表并不明显,这与新丰江大坝峡谷区分布的北东东向断裂特征具有一致性.研究区基底埋深约1.2～2.5 km,新丰江水库下方基底相对两侧呈现上隆.上地壳下部层速度较为均匀,层厚度无明显变化,上、下地壳分界面埋深20.5～21.5 km.下地壳存在一弱低速层体,莫霍界面由南东向北西呈缓慢加深的趋势,起伏变化不大.埋深约31.0～32.5 km.沿剖面地壳平均速度6.21～6.25 km/s.
A deep seismic reflection / refraction profile was completed centered on the Xinfengjiang reservoir.The two-dimensional velocity structure images of the crust and mantle along the profile were obtained by dynamic ray tracing method.The results show that the dam located at southeast of Xinfengjiang reservoir The gorge area to the Heyuan area have obvious vertical and horizontal inhomogeneity in the velocity structure between the upper crust basement interface and the C 1 interface (the upper crust upper bottom surface), and the velocity is characterized by high and low velocity interphase distribution. The analysis of the exact location of local earthquakes shows that the distribution of earthquakes has a good correlation with this structural anomaly area.It is presumed that there may exist at least deep faults near the upper crust of 120 km in the profile.The fault mainly consists of Main and close to the surface are not obvious, which is consistent with the NE-EAST fault distribution in the dam and canyon area of Xinfengjiang.The buried depth of the study area is about 1.2-2.5 km, and the base of the Xinfengjiang reservoir is relatively two The upper crust has a top-up velocity.The velocity of the lower crust is relatively uniform with no significant change in layer thickness, and the upper and lower crust interfaces are buried at 20.5-21.5 km with a weak low-velocity layer in the lower crust. North West declines gradually deepened, undulating change. Depth of about 31.0 ~ 32.5 km. The average rate of 6.21 ~ 6.25 km / s crust along the profile.