龙门山中段及邻区地壳密度结构及其地球动力学启示  

Crustal density structure of the central Longmenshan and adjacent area and its geodynamic implications

作　　者：王芃[1,2] 张忠杰[3] 张晰[3] 韩颜颜[2,3] 王敏玲[2,3] 侯爵[2,3] 徐涛[3] 

机构地区：[1]中国科学院广州地球化学研究所,广州510640 [2]中国科学院大学,北京100049 [3]中国科学院地质与地球物理研究所,岩石圈演化国家重点实验室,北京100029

出　　处：《岩石学报》2014年第4期1179-1187,共9页Acta Petrologica Sinica

基　　金：国家"深部探测技术与实验研究"专项课题(SinoProbe-03-02);国家973计划项目(2011CB808904);国家自然科学基金项目(40930418;41274090;41174075;41021063;41174043)联合资助

摘　　要：龙门山是我国东西构造、地貌分界线的重要组成部分。其两侧的岩石圈结构差异,是形成龙门山造山带的主要原因之一,并对龙门山的构造演化起着持续影响。为了解龙门山两侧壳幔结构差异,本文从重力角度探讨跨龙门山地区的地壳密度结构。我们使用EGM2008模型的重力异常数据,以最新的阿坝-遂宁人工源地震剖面速度模型为基础,得到了龙门山造山带中段及其邻区的精细地壳密度结构。密度结构显示松潘-甘孜地区和四川盆地分别具有软弱和坚硬的下地壳。根据本文所得到的地壳密度结构模型,我们认为龙门山的隆升主要受印度洋板块与欧亚大陆板块的陆-陆碰撞作用影响,强烈的挤压作用使青藏高原物质向东运移,东移物质在青藏高原东缘龙门山地区受到坚硬的四川盆地的阻挡转而向上运移,造成了龙门山的隆升。Longmenshan is an important part of the topographic and tectonic boundaries in China. The varied lithospheric structure on two sides of Longmenshan could take part in the formation of Longmenshan orogenic belt and have a lasting effect on the evolution of Longmenshan. In order to understand the differences between the structure of crust and mantle on two sides of Longmenshan, we constructed the density structure under a profile crossing central Longmenshan. Based on gravity anomaly data from EGM2008 model and crustal P-wave velocity structure from the latest Aba-Suining deep seismic sounding profile, we obtained detailed crustal density structure of central Longrnenshan and adjacent area. The density structure showed weak lower crust in Songpan-Ganzi, strong lower crust in Siehuan Basin and upwelling of material from lower crust beneath Longrnenshan. Based on the crustal density structure obtained in this study, we suggest that the uplift of the Longmenshan has been mainly controlled by the continent-continent collision between the Indian plate and the Eurasian plate, which has forced the crustal material of the Tibetan Plateau move eastward. While restricted by the rigid Sichuan basin, the crustal material of the Songpan-Ganzi in eastern part of the Tibetan Plateau move upward, and this could be the reason for the uplift and formation of the Longmenshan.

关 键 词：龙门山 四川盆地 EGM2008 密度结构 

分 类 号：P541[天文地球—构造地质学] P631[天文地球—地质学]