青藏高原东北缘基底结构研究——玛多—共和—雅布赖剖面上地壳地震折射探测

A study on the basement tectonic units in the northeast margin of Tibetan plateau—the result of Maduo-Gonghe-Yabrai refraction profile

利用青藏高原东北缘玛多-共和-雅布赖人工地震测深剖面的沉积盖层及上地壳折射波Psed、Pg走时,使用正则化方法反演该剖面基底速度结构,并通过射线数分布、分辨率分析等手段分析反演结果的可靠程度,得到了沿剖面850km近地表沉积盖层及结晶基底结构性质及构造变化特征,揭示了巴颜喀拉块体中段、东昆仑—西秦岭褶皱带、祁连褶皱带东侧及阿拉善块体等四个一级地质构造单元以及各块体内部若干次级构造沉积盖层介质岩性及厚度,结晶基底性质及被改造特征,在此基础上分析了(沿测线)青藏高原东北缘与外围阿拉善块体、高原内部块体间上部地壳构造耦合以及与地表构造形态关系.

The regularization inversion is used to get the basement structure of Maduo-GongheYabrai profile with the travel time data of refraction wave Pg and Psed.The checkerboard test,resolvability method and travel-time fitting are used to prove the reliability of the inversion.We got the features of the sedimentary cover and crystalline basement along the 850 km profile.The result shows the lithology and the depth of the four first-order tectonic units（Bayan Har Block,Eastern Kunlun-Western Qinling fold belt,the east side of Qilianshan fold belt and Alxa Block）and the secondary structure inside them.The properties and transformations of the crystalline basement are revealed too.On this basis,the upper crust structure coupling among blocks is analyzed.The relationships between the upper structures and the surface are also analyzed.