Abstract: The Tianshan Mountains originated from continent-continent collision during late Paleozoic era,and has experienced typical intra-continental orogenic process during Mesozoic-Cenozoic era. The architecture and activity of the shallow and deep structures of the Tianshan Mountains have attracted the attention of many geoscientists. Based on several geophysical prospecting data and comprehensive geological tectonic study,the shallow and deep structures of the middle segment of the Tianshan Mountains have been mapped in the light of the Tianshan Geoscience Transect. The result shows that the main geological units associated with the complexity of deep structures are displayed symmetrically from old to young on both sides of the suture zone of continental collision in Paleozoic era. This may reflect the collision process and the tectonic evolution in the later geological period. It is discovered that a low-velocity and high-conductivity layer of about 200km in width and about 10km in thickness exists on top of the upper mantle beneath the middle segment of the Tianshan Mountains. It is considered to be the residual lower crust resulted from the delamination between the crust and mantle due to the rejuvenated orogenic process of the Tianshan Mountains during Mesozoic-Cenozoic era.

Key words: Geoscience Transect, shallow and deep structures, delamination, Tianshan

摘要： 天山起源于古生代的陆-陆碰撞作用,又经历了中新生代的典型陆内造山过程,其深浅构造结构和活动性一直是众多学者关注的热点。文中通过多种地球物理探测和综合地质构造分析,以地学断面形式对其深浅构造进行填图,揭示了天山中段复杂的深浅构造特色。结果表明:沿古生代的陆-陆碰撞缝合带两侧分别呈现出主要构造地质单元由老到新的对称性,并伴有相应深部结构的复杂性,反映了碰撞过程及后期的构造演化特点;天山中部的上地幔顶部存在厚近10km、宽近200km、几乎涵盖整个天山的低速高导层,可能是中新生代以来天山的陆内再造山作用引起的壳幔拆沉作用形成的残留下地壳。

关键词: 地学断面, 深浅构造, 拆沉作用, 天山