松辽盆地东缘域地壳结构及其地质意义:深反射地震  

Crustal structure between the eastern margin of the Songliao Basin and its geological implication:deep seismic reflection

作　　者：王建民 杨宝俊[2] 李占林 于春玲 江才君 李鹏[2] 曹来圣 陈智 WANG JianMin;YANG BaoJun;LI ZhanLin;YU ChunLing;JIANG CaiJun;LI Peng;CAO LaiSheng;CHEN Zhi(Daqing No.1 Geophysical Exploration Company of BGP,CNPC,Daqing 163357,China;College of Geo-exploration Science and Technology,Jilin University,Changchun 130026,China;Daqing Geophysical Research Institute of BGP,CNPC,Daqing 163357,China)

机构地区：[1]中国石油集团东方地球物理公司大庆物探一公司,大庆163357 [2]吉林大学地球探测科学与技术学院,长春130026 [3]中国石油集团东方地球物理公司大庆物探研究院,大庆163357

出　　处：《地球物理学报》2020年第9期3478-3490,共13页Chinese Journal of Geophysics

基　　金：中石油集团公司科技攻关项目(3R211ZZ54423)资助.

摘　　要：松辽盆地东缘域位于松嫩—张广才岭微板块东部.自晚古生代以来该域经历了西拉木伦河缝合带闭合产生的北向挤压作用、蒙古—鄂霍茨克洋自西向东剪刀叉式闭合对其东侧东南侧产生的挤压作用以及西太平洋板块西向变向俯冲产生的挤压作用等区域构造应力场影响,从而产生了复杂的地壳变动.该东缘域的地壳结构与松辽盆地地壳是否具有相近的结构特点,这是至今未被研究的内容.在Songliao Drep研究中已经用深反射地震手段得到松辽盆地地壳结构的一组新认识.这些认识在其东缘域是否还成立,也需要用同样精度的手段予以研究.另外,莫霍界面的宏观特征与微观(内部)特征,从松辽盆地到其东缘域有什么样的变化,其形成机理是什么,也需要进一步研究.为了回答这些科学问题,从哈尔滨西至尚志市附近实施了一条东西向约150 km长的深反射地震剖面.通过研究发现东缘域与松辽盆地基底地壳具有明显的差别,即由松辽盆地地壳的三分性变到东缘域盆地外地壳的二分性,在剖面近东端得到近26 km深的莫霍界面深度,并用均衡理论分析莫霍界面形态特征的形成机理;上部地壳存在双向大型推覆断裂,推测其被推覆体主体是古亚洲洋沉积地层即C-P系海相地层.这些认识为中国东北地区探查晚古生代海相地层、研究东北亚地壳结构特征提供了理论依据.In tectonics,the east margin of the Songliao basin lies in the east of the Songnen-Zhangguangcai mountain microplate,which has experienced the influences of the regional tectonic stress field,such as the northward extrusion generated by closing of the suture zone in Xilamulun River,and the extruding at the east and north-east side of the domain generated by scissor-type closing from west to Wast of the Mongolia-Okhotsk ocean,as well as the extruding generated by westward subduction of the western Pacific plate,thus resulting in complicated crustal variation.A series of new understandings have been obtained by deep seismic reflection in the Songliao-Drep research.While whether these knowledge are also correct for the eastern margin of the basin remains unclear.In addition,what kind of changes took place in the macro and micro characteristics of the Moho-discontinuity from the Songliao basin to its east margin and what is the formation mechanism are also needed to be further studied.In order to answer these questions,a west-east deep seismic reflection profile was set up,which extends from the west of Harbin to the nearby Shangzhi city with a length about 150 km.The research shows that there is an obvious crustal difference between the east margin domain and Songliao basin,i.e.from the tri-partition of Songliao basin crust changing into the bi-partition of the east margin.The depth of the Moho-discontinuity is about 26 km at the east edge of the profile,and the formation mechanism of its morphology can be explained by the equilibrium theory.A group of large two-way thrusting structures are present in the upper crust,and the main body overridden is speculated to be the palaeo-Asian ocean sedimentary layer,that is the C-P system marine facies layer.These understandings provide a theoretical basis for further investigating Neopaleozoic marine facies strata in Northeast China as well as crustal structure of Northeast Asia.

关 键 词：松辽盆地东缘域 哈尔滨—尚志深反射地震剖面 松嫩—张广才岭微板块 二分地壳结构 C-P系海相地层 

分 类 号：P315[天文地球—地震学] P631[天文地球—固体地球物理学]