南天山西段前陆褶皱冲断带平衡剖面分析

Balanced Section Analysis of Fore-land Fold-thrust Belt in Southern Tien Shan Western Part

平衡剖面技术是一种基于几何守恒原理的应用于造山带和盆地结构恢复的方法。本文以挤压环境下形成的南天山西段前陆褶皱冲断带为例,对其典型二维地震剖面进行变形分析和平衡剖面恢复。结果表明,从平面上可将该冲断带划分为多排近似平行、东西走向的背斜带,由南往北依次为喀什、阿图什、托帕-康西维尔和喀拉伯克托尔-温古尔背斜带;从剖面上可以将该冲断带划分为两个不同层次的推覆构造系统:浅层为大规模叠瓦式冲断系统;深层为原地隐伏双重冲断构造系统。对重点剖面进行平衡剖面分析,得出自上新世以来研究区南北构造缩短量为49.1km,缩短率为50.51%,地壳平均缩短速率为13.72mm/a。

The technique of balanced section is based on the geometric conservation principle to restore the structure of orogenic and basin.Took the Western part of the foreland fold-thrust belt in Southern Tien Shan for example,which formed in a compressional tectonic setting,this paper analysed tectonic deformation and the balanced section of the typical 2D seismic profiles in this area. The result shows that the fold-thrust belt can be divided into several rows of anticlines on plane which are almost parallel and E-W-trending, such as Kashi,Atushi,Tuopa-Kangxiweier and Kaboketuoer- Wenguer from south to north. In profile, it can be divided into two different levels of thrust system：The shallow part is a large scale imbricate thrust system;the deep structure is in-situ buried duplex structure system. Analysed the balanced section of the key profile in this area, concluding that this area is shortened by 49.1 km （from north to south）since Plioeene in shortening ratio of 50.5 1%,its average crustal shortening rate is 13.72 mm/a.