南天山库车褶皱冲断带构造几何学和运动学

GEOMETRY AND KINEMATICS OF THE KUQA FOLD-AND-THRUST BELT IN THE SOUTHERN TIANSHAN

印度板块与欧亚大陆的汇聚作用和持续碰撞使中亚内陆沿天山、昆仑山、阿尔金山发生变形 ,山脉前沿发育褶皱冲断带。南天山库车褶皱冲断带中段库车河地区发育 3～4排东西走向的逆冲 (掩 )断层和相关褶皱 ,逆冲 (掩 )断层由北向南扩展 ,断层和褶皱的形成时代自北向南逐渐变新 ,北部山前带的变形发生于前中新世 ,南部秋立塔克背斜带和亚肯背斜带的变形时代为上新世 (5 2± 0 2Ma)。通过构造几何学和运动学分析 ,作者提出了库车褶皱冲断带的构造变形方式和演化模型。

The Tianshan was one of the largest and the most active intracontinental mountain ranges in the world. The active fold and thrust belts flanked both sides of the mountains. The Kuqa fold and thrust belt of the southern Tianshan extended for 350 km along strike and reached a maximum width at 80～100 km. Using detailed surface geology survey, seismic reflection profiles and satellite images, the paper described a profile section across the central part, the Kuqa river area, of the Kuqa belt. The Kuqa fold and thrust belt was divided into four structural units, which were, in southward order, the North Linear Anticline Zone, the Keyi Thrust Zone, the Quilitake Anticline Zone and the Yaken Anticline Zone. The east west trending fault related folds should be basic deformation styles of the belt. The deformation was propagated from the north to the south in the belt. The unconformity between the Miocene Jidike Formation and the Paleogene Sueyi Formation in the north region of the belt implied that the timing of deformation might be in the pre Miocene on the North Linear Anticline Zone and the Keyi Thrust Zone. The growth strata in the south region of the belt indicated the syntectonic sedimentary strata of the Yaken Anticline. Combining with the magnetostratigraphic sections on the both sides of the East Quilitake Anticline, the timing of deformation was represented in Early Pliocene(5 2±0 2 Ma)on the Quilitake Anticline Zone and the Yaken Anticline Zone, and the slip rate of the major thrust fault of the Quilitake Anticline Zone being 1 5 mm/a in average since Early Pliocene.