库车坳陷克深地区先存被动盐底辟挤压变形数值模拟  

Numerical Simulation of Compressional Deformation of Pre-existing Passive Salt Diapir in Keshen Area of Kuqa Depression

作　　者：吴超[1] 徐雯峤 李青[1] 汪伟[2] 陈维力 尹宏伟[2] 屈元基 WU Chao;XU Wenqiao;LI Qing;WANG Wei;CHEN Weili;YIN Hongwei;QU Yuanji(Exploration and Development Research Institute,PetroChina Tarim Oilfield Company,Korla 841000,China;School of Earth Sciences and Engineering,Nanjing University,Nanjing 210023,China)

机构地区：[1]中国石油塔里木油田分公司勘探开发研究院,库尔勒841000 [2]南京大学地球科学与工程学院,南京210023

出　　处：《高校地质学报》2023年第2期240-250,共11页Geological Journal of China Universities

基　　金：国家深地专项专题(2019YFC0605505);国家自然科学基金项目(41972219,41572187,41927802)联合资助。

摘　　要：库车褶皱冲断带是一个典型的复杂含盐褶皱冲断系统。文章基于地震资料构造解析,采用离散元数值模拟方法,设计了2组数值模拟实验来探究先存被动盐底辟对含盐的双滑脱层褶皱冲断带构造形态及演化的影响,从而分析克深5构造区沿走向分段差异的盐构造变形特征和机制,并对盐下断层活动进行精细的定量分析。模拟结果表明先存被动盐底辟作为挤压构造变形优先发育的位置,是应力释放的优先区域,影响了盐上断层顺序和盐下断层的活动性,进而控制了构造沿走向的差异演化。通过将模拟结果与库车坳陷克深5构造区构造特征进行对比分析,吐孜玛扎背斜是盐盆地内部先存被动底辟受后期挤压变形的产物。吐孜玛扎背斜吸收大部分的缩短量,造成紧邻的盐下断片显著抬升,盐上受同构造沉积影响在背斜北侧形成一个宽缓的向斜,抑制了向斜内乱序断层的形成。先存被动盐底辟构造是控制克深5区域构造变形的主要控制因素之一。研究区东段不含先存被动盐底辟,依次发育有库木格列木背斜和喀桑托开背斜,背斜变形幅度向盆地方向减小,盐下断裂活动强度向盆地方向减弱,研究区西段含先存被动盐底辟,发育吐孜玛扎背斜,先存被动盐底辟的盐下断裂活动强度强于毗邻的断层。Kuqa fold-thrust belt is a typical complex salt-bearing fold-thrust system.In this paper,based on seismic interpretation,two discrete element models are designed to explore the influence of pre-existing passive salt diapir on the structural geometry and evolution of double-detachment fold-and-thrust belts,as well as the causes behind the different salt structural deformation characteristics and mechanism of the strike segment in Keshen 5 structural area,and the slip displacement of subsalt faults are analyzed finely.The simulation results show that the pre-existing salt diaper,as the priority location of compressional structural deformation and the priority area of stress release,affects the sequence of faults in subsalt layer and the slip displacement of subsalt faults,proceeding to control the differential evolution of structures along the strike.Comparing the simulation results and structural features of Keshen 5 structural area in Kuqa depression,we suggest that the Tuzimazha anticline is the result of the subsequent compressional deformation of the pre-existing passive diapir in the salt basin.The Tuzimazha anticline absorbs most of the shortening,resulting in a significant uplift of the adjacent subsalt fragments,and a wide and gentle syncline is formed on the north side of the anticline under the influence of syntectonic deposits,which suppresses the formation of disordered faults in the syncline.The pre-existing salt diapir structure is the main controlling factor controlling the tectonic deformation in Keshen 5 area.There is no pre-existing salt diapir in the eastern part of the study area,Kumugelemu anticline and Kasangtuokai anticline are developed in turn,the amplitude of which decreases towards the basin,and the slip intensity of subsalt faults weakens towards the basin.The western part of the study area contains pre-existing passive salt diapir.Tuzimaza anticline is developed,and the activity intensity of subsalt faults under pre-existing passive salt diapir is stronger than that of adjacent faults.

关 键 词：库车坳陷 先存被动盐底辟 离散元 应力应变 构造变形 

分 类 号：P542.3[天文地球—构造地质学]