中国西北大陆碰撞带的深部特征及其动力学意义  

DEEP FEATURES OF CONTINENTAL COLLISION BELTS IN NORTHWESTERN CHINA AND THEIR DYNAMIC IMPLICATIONS

作　　者：胥颐[1] 刘福田[1] 刘建华[1] 陈辉[1] 孙若昧[1] 

机构地区：[1]中国科学院地质与地球物理研究所,北京100101

出　　处：《地球物理学报》2001年第1期40-47,T002,共9页Chinese Journal of Geophysics

基　　金：国家自然科学基金项目!(494 74 2 1 4 )

摘　　要：以中国大陆西北地区地震层析成像的结果为基础 ,通过分析大陆块体内部岩石层和软流层的深部形态 ,提出西部造山带与相邻块体之间几种可能的碰撞类型 :天山与塔里木之间存在地块的嵌入拼合、俯冲、岩石层拆离下沉以及层间插入等多种构造样式 ;青藏高原与北部地质单元之间存在十分清晰的深部边界 ,反映出上地幔物质向北扩展的痕迹 ;推测青藏高原的岩石层在向北运动的过程中由于受到塔里木刚性块体的阻滞发生弯曲甚至折断 ,但是祁连山以北较浅的软流层相当于一个开放边界 ,使高原的上地幔物质得以进一步向北迁移 .大陆碰撞不仅造成中国西部造山带岩石层结构的变动 ,而且导致软流层中一部分熔融的岩浆体沿着碰撞边界上涌到岩石层底部 。Possible colliding types between orogenic belts and adjacent blocks are recognized in northwestern Chinese continent by analyzing the deep frames of the lithosphere and asthenosphere of continental blocks,based on the results of seismic tomography. Several tectonic patterns,such as the embedding, subducting,detaching and lateral inserting of continental lithosphere,are observed between the Tianshan and Tarim regions. Sharp deep boundaries exist between the Qinghai Xizang Plateau and its northern geological provinces,showing the evidences of upper mantle flowing to north. It is inferred that the lithosphere of the Qinghai Xizang Plateau has been flexed or broken in the northward moving process,resisted by the rigid Tarim block. Nevertheless,the shallower asthenosphere north of the Qilian mountain seems to be a free boundary,which makes the upper mantle substances beneath the plateau transporting northward much further. Continental collision not only changed the lithospheric structure of the orogenic belts in western China,but also resulted in the mantle upwelling from asthenosphere to the base of lithsophere along the colliding boundary. They have played a key role in the evolution of the plateau and other orogenic belts in western China. [

关 键 词：地震层析成像 西北土地区 造山带 青藏高原 岩石层 大陆碰撞 中国 

分 类 号：P542.2[天文地球—构造地质学]