利用地震走时反演阿尼玛卿缝合带东段及两侧基底结构*
潘纪顺1,2,颜廷松1,徐朝繁2,张先康2,刘 志2,潘素珍2,王帅军2

(1.华北水利水电学院,郑州 450011; 2.中国地震局地球物理勘探中心,郑州 450002)

基底; 阿尼玛卿缝合带; 结构; 射线方法; 低速带

Basement Structure of A'nyemaqen Suture Zone and Its Adjacent Areas Determined by Seismic Traveltime Inversion
PAN Ji-shun1,2,YAN Ting-song1,XU Zhao-fan2,ZHANG Xian-kang2,

(1.North China University of Water Conservancy and Electric Power,Zhengzhou 450011,Henan,China)(2.Geophysical Exploration Center,CEA,Zhengzhou 450002,Henan,China)

basement,A'nyemaqen suture zone,structure,ray method,low velocity zone.

备注

对11炮宽角地震反射/折射的Pg波走时数据进行了反演,结果表明:阿尼玛卿缝合带东段基底速度结构整体呈低速带分布,两侧的速度分布相对均匀; 缝合带内基底界面剧烈下凹,最深达5.5 km,不存在稳定的基底界面; 松潘—甘孜微块体基底界面整体埋深达3.5 km,相对平坦,其中部略微下凹; 从缝合带过渡到西秦岭褶皱带,基底界面急剧抬升至1.8 km,之后迅速下降至4.7 km,然后趋于平坦; 缝合带的地壳变形存在挤压和走滑两种形式,在缝合带及邻近地区,上部地壳物质曾有过向北方向逃逸的迹象。

The inversion results of the Pg data acquired by wide-angle seismic reflection/refraction data of 11 shots reveal that the basement velocity structure of the eastern part of A'nyemaqen suture zone is characterized by a low velocity zone while the velocity is even in its adjacent areas.The basement in A'nyemaqen suture zone is concave dramatically.Its maximum depth is about 5.5 km in it.The depth of the basement interface in Songpan-Ganzi block is about 3.5 km,and it is flat.The concave feature of the basement interface also appears in the middle part of Songpan-Ganzi block.In the transition zone between A'nyemaqen suture zone and West Qinling fold zone,the basement shallows rapidly up to a depth of 1.8 km,then deepens northwards up to 4.7 km,and finally becomes flat.There exist two kinds of crustal deformation,namely squeezing and striking in A'nyemaqen suture zone.The upper substance of crust has ever escaped northwards.