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龙门山地区的深部构造研究对于龙门山断裂带的深部驱动机制有重要的意义,但由于天然地震太站分布较少,难以获得水平分辨较高覆盖整个龙门山地区的深部构造图像.本文利用最新中德合作在龙门山断裂带两侧布置的天然地震阵列式台站数据,获取了各个台站的接收函数波形数据.通过对H-K叠加方法的研究和改进,并应用到各个台站的实际接收函数数据分析上,获得了断裂带两侧以及沿断裂带的地壳厚度和平均速度比的分布,通过进一步插值形成了覆盖整个龙门山地区的水平分辨20Km的Moho面三维形态.综合对应的速度比和深部物质赋存状态关系的研究,获得以下结论:四川盆地属于平均厚度35~40km冷地壳,松潘和夹金山等山区地壳则属于厚45~50Km的热地壳.而沿断裂带变化比较明显,南段类似高原地区有热而厚的地壳,中段为40~45 km的正常地壳,个别地形突起处深约50 km.北段则逐渐向盆地的冷而薄的地壳过渡,厚度从43~40 km逐渐变化.Moho面的分布特征表明了龙门山断裂带的中部和南部的差异,并推测其间存在一个明显的Moho面异常突起带,与该过渡带的余震的缺失存在一定的关联.
The study of deep structure in the Longmenshan area is of great significance to the deep driving mechanism of the Longmenshan fault zone.But it is difficult to obtain the deep structure images covering the entire Longmenshan area due to the low distribution of natural earthquakes.This paper uses the latest The natural seismic array station data arranged on both sides of the Longmenshan fault zone by Sino-German cooperation acquired the reception function waveform data of each station.Through the research and improvement of the HK superposition method and applied to the actual reception of each station In the function data analysis, the crustal thickness and average velocity ratio distributions on both sides of the fault zone and along the fault zone were obtained, and the 3-D Moho plane horizontal resolution of 20Km was formed through further interpolation. The corresponding velocity ratio It is concluded that the Sichuan Basin belongs to the cold crust with the average thickness of 35 ~ 40km and the crust in the Songpan and Jiajinshan mountains belong to the thermal crust with the thickness of 45 ~ 50Km, while the changes along the fault zone are obvious, The southern section is similar to the plateau with hot and thick crust, and the middle section is normal crust with 40 ~ 45 km. The depth of some terrain projection is about 50 km. The northern section gradually transitions to the cold and thin crust of the basin, and the thickness gradually changes from 43 to 40 km. The distribution characteristics of the Moho surface indicate the differences between the central and southern parts of the Longmen Shan fault zone and the existence of a distinct Moho surface The anomaly zone is related to the absence of aftershock in the transitional zone.