翁牛特东部地区基底折射资料的二维反演
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摘要
本文介绍采用相遇观测系统中全部走时分支曲线双向同时二维反演拟合法，对翁牛特东部地区的三条剖面基底折射资料进行二维反演，文中展示了各条剖面的实测与理论走时对比图、射线追踪图、二维速度结构分布图、一维速度柱状图以及理论地震图。结果表明：本区中生代前基底顶界面基本呈中间深两边浅的浅凹状形态，基底顶面埋深最深处达１．５ｋｍ左右；速度沿横向和纵向都是不均匀分布的。中生代前基底顶界面速度沿界面在５．６ｋｍ／ｓ～５．９ｋｍ／ｓ之间变化，在纵向上变化不大，速度梯度只有０．０１（ｋｍ／ｓ）／ｋｍ
According to the method which is simultaneous inversion for two dimensional(2 D,i.e.,lateral variation) velcity structure with all the two reversed travelling time in reversed observation system,the 2 D inversion by refractional data along three profiles in Eastern Wengniute area has been introduced in this paper.Saveral maps which include travelling time picture to make a comparison between theory and observation, ray tracing picture,2 D velocity structure picture,1 D velocity post picture and synthetic seismogram along every profile are displayed in the paper.The results show that in this area,① the top surface of the base before Mesozoic exists mainly in the shallow hollow shape along all the three profiles,and its maximum buried depth reaches about 1 67km;②the velocity distribution is inhomogeneious both horizontally and vertically The velocity changes from 5 6km/s to 5 9km/s along the top inter face of the base before Mesozoic,and vertical change is little,and its gradient is only 0 01 (km/s)/km or so
According to the method which is simultaneous inversion for two dimensional(2 D,i.e.,lateral variation) velcity structure with all the two reversed travelling time in reversed observation system,the 2 D inversion by refractional data along three profiles in Eastern Wengniute area has been introduced in this paper.Saveral maps which include travelling time picture to make a comparison between theory and observation, ray tracing picture,2 D velocity structure picture,1 D velocity post picture and synthetic seismogram along every profile are displayed in the paper.The results show that in this area,① the top surface of the base before Mesozoic exists mainly in the shallow hollow shape along all the three profiles,and its maximum buried depth reaches about 1 67km;②the velocity distribution is inhomogeneious both horizontally and vertically The velocity changes from 5 6km/s to 5 9km/s along the top inter face of the base before Mesozoic,and vertical change is little,and its gradient is only 0 01 (km/s)/km or so
引文
1李平．地震折射波资料解释中射线方法应用的进一步探讨．东北地震研究，1992，8（4）2HuangHuaiyong，C．Spencer＆A．Green．Amethodfortheinversionofrefractionandreflectiontvaveltimesforlateralyvaryingvelocitystructures．Bul．Seis．Soc．Am．，Vol．76，No3，PP．837－846，June1986．
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