新疆叶城—西藏狮泉河重力剖面与地壳结构

THE CRUST STRUCTURE AND GRAVITY PROFILE OF YE CHENG, XINJIANG-SHI QUANGHE, TIBET

本文利用西藏狮泉河—新疆叶城的剖面重力测量成果,对该区的大地构造、地壳厚度以及均衡信息进行讨论。结果认为,研究区内藏北与羌塘构造区地壳厚度平均为70km,到昆仑褶皱区,地壳厚度大致以8°的倾角从南向北呈现由厚变薄的大梯度带,进入塔里木盆地边缘,厚度大致为50km.根据均衡信息的分析,本区可分为三种类型,即藏北与羌塘的均衡补偿区;昆仑褶皱带的正均衡异常区;塔里木盆地南缘的负均衡异常区.青藏高原冰川融化引起的均衡上升运动与构造力引起的结果相比是非常微弱和从属的,并属后期阶段.

The tectonics, the Moho-depth and the isostatic message of the investigated region are discussed on the basis of gravity survey. It is concluded that: the average Mohodepth of the North Tibet and Qing-tang area is about 70 km. In the area of Kun Lun fold, Moho-depth is inclined at about 8° upward to the north. It is a great gradient belt which tends gradually shallower from south to north. Within the boundary of Tarimn Basin, Moho-depth is about 50km.According to the analysis of isostatic message, three types of area are divided in this region: The area of North Tibet and Qing-tang is presented in an isostatic compensation; the area of Kun Lun folded belt is presented by positive isostatic anomalies; the South boundary of Tarimn Basin is presented by negative isosatic anomalies. Isostatic ascending motion, which was resulted from the glacial dissolve of the Qinghai Tebet plateau, is much weaker and Less important than that of the structure force and it belongs the later period stage.