INVERSION OF THE UPPER CRUSTAL VELOCITY STRUCTURE IN CAPITAL AREA WITH PG WAVE
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摘要: 为了弄清首都圈地区上地壳速度精细结构,本文使用了迄今为止在我国大陆最为密集炮间距高分辨折射和宽角反射/折射综合地震测深剖面-天津-北京-赤城剖面的Pg波走时资料,反演了首都圈地区的上地壳速度结构。根据上地壳速度结构特征,可将整个剖面大致分为华北盆地拗陷区和燕山台褶隆起区,其中华北盆地又可以细分为黄骅拗陷、沧县隆起、骥中拗陷等,大厂拗陷、通县隆起、北京拗陷和京西隆起为燕山隆起区的前缘部分。华北平原区以低速结构的拗陷为主,地表速度较低,基底埋深深,盖层厚,垂直速度梯度大;而在燕山山区则以高速结构的隆起为主,地表速度较高,基底埋深浅,盖层较薄,垂直速度梯度小。基底面起伏大,最深处达到6km以上,最浅处不足1km。Abstract: The velocity structure in the upper crust of Capital Area is inversed with the Pg wave travel time data, which is the seismic sounding data with densest explosion distance and high resolution from Tianjin-Beijing-Chicheng DSS profile.The results show that the profile can be divided into North China Basin and Yanshan Uplift, and the former can be also divided into Huanghua depression, Cangxian upheaval, Jizhong depression and so on.Dachang depression, Tongxian upheaval, Beijing depression and Jingxi uplift belong to the front edge of Yanshan Uplift.It is mainly lower velocity depression in North China plain area, with lower surface velocity, deeper basement, thicker cover strata and high gradient vertical velocity.Whereas in Yanshan Uplift, it is mainly higher velocity upheaval, with high surface velocity, shallower basement, thinner cover strata and lower gradient vertical velocity.The basement undulates greatly, which reaches 6km at deep region, but can not get 1km at shallow area.
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Key words:
- Capital Area /
- Pg wave traveltime /
- inversion /
- upper crust structure /
- North China Basin /
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