库车坳陷秋里塔格褶皱带几何学和运动学特征与油气圈闭

Properties of geometry and kinematics related to hydrocarbon traps in Qiulitag anticline zone of Kuqa Depression

秋里塔格褶皱带是南天山库车前陆冲断带的前缘隆起。通过对地震反射资料的时间—深度转换,结合遥感资料的倾角处理成果及野外实测产状数据,建立较为精确的二维构造剖面,详细阐述了断层相关褶皱在秋里塔格褶皱带的分布及其几何学、运动学特征。研究表明,秋里塔格褶皱带东段、中段深部构造变形表现为台阶状逆断层及其相关褶皱,台阶状逆断层的断坡受早期断陷盆地边缘正断层规模和沉积厚度的控制,断坡高度自东向西由3km递减为1km,构造变形样式相应由单阶断层转折褶皱转换为双重叠加构造;而在秋里塔格褶皱带西段,构造缩短主要被下第三系库姆格列木组内部滑脱断层及下伏枕状膏泥岩所吸收,台阶状逆断层及其相关褶皱消失,东、西段构造类型的差异对“西油东气”的分布格局具有控制作用。

The Qiulitag anticline zone is the thrust front of the Kuqa thrust-and-fold belt along the southern piedmont of Tianshan Mountain. The data of surface geology, two-dimensional seismic reflection profiles and stereoscopic remote-sensing measurements were integrated and used to construct the balanced geologic cross sections and define the subsurface fault and fold geometry. These approaches provide insights into fold-and-thrust belts, where subsurface data are limited. The shape of the thrust faults underlying Qiulitag anticline was controlled by the architecture of the rift basin. The ramp height of the deep fault system was declined from three kilometers in the east regional cross section to one kilometer westward, where an imbricate fault was developed. A three-dimensional geometrical and kinematical model was constructed, and the deformational mechanism was analyzed. The different structures in eastern and western Qiulitag anticline zone resulted in the different types of traps, which controls the hydrocarbon accumulation in the Qiulitag anticlinge zone.