帕米尔突刺东缘冲断带构造形成机制:物理模拟及讨论  

Characteristics and Formation Mechanism of Thrust Structures in the Eastern Margin of Pamir Salient: Insights from Analogue Modeling and Discussion

作　　者：吴珍云[1] 尹宏伟[2] 张涛[3] 范小平[4] WU Zhenyun;YIN Hongwei;ZHANG Tao;FAN Xiaoping(Earthquake Administrator of Jiangsu Province, Nanjing 210014, Jiangsu, China;School of Earth Sciences and Engineering, Nanjing University, Nanjing 210046, Jiangsu, China;Shenyang Geological Survey, CGS,Shenyang 110034, Liaoning, China;Department of the Urban Rail Transit, Nanjing Tech University, Nanjing 210009, Jiangsu, China)

机构地区：[1]江苏省地震局,江苏南京210014 [2]南京大学地球科学与工程学院,江苏南京210046 [3]中国地质调查局沈阳地质调查中心,辽宁沈阳110034 [4]南京工业大学交通运输学院,江苏南京210009

出　　处：《大地构造与成矿学》2017年第4期663-677,共15页Geotectonica et Metallogenia

基　　金：江苏省地震局青年基金重点项目(201602);国家自然科学基金(41272227;41602208);中国地震局地震科技星火计划(XH16013)联合资助

摘　　要：利用物理模拟实验,建立了两个不同边界条件的模型分别模拟帕米尔突刺东缘柯克亚-和田褶皱冲断带和喀什-叶城转换断层带的逆冲走滑构造演化过程,进而分析和讨论了研究区构造变形特征和变形机制。物理模拟实验结果表明:(1)帕米尔突刺东缘的柯克亚-和田褶皱冲断带和喀什-叶城转换断层带均形成于压扭应力场作用下,发育明显断层走滑现象,前者逆冲前缘断层兼具左行走滑特征,后者逆冲前缘断层则具右行走滑特征,但前者总体走滑量明显小于后者;(2)帕米尔突刺东缘的柯克亚-和田褶皱冲断带和喀什-叶城转换断层带走滑作用均主要位于山前边界断层带,越靠近逆冲前缘(盆地内部),走滑效应越微弱,挤压效应越明显;(3)在边界走滑断层前缘(往盆地方向),弧形断裂由挤压方向向前依次产生,并且斜向相交,验证了帕米尔东缘冲断带构造演化符合自南向北依次变新的规律;(4)在斜向压扭作用过程中,走滑断层构造带不一定发育明显的高角度甚至直立的断层,也可能表现为逆冲叠瓦构造楔样式,形成走滑逆断层,故在进行帕米尔突刺东缘(如塔西南山前)地震剖面构造解析时应充分关注这种构造类型。Two models with different boundary conditions were carried out to simulate the structural evolution of theKekeya?Hetian fold-and-thrust belt and Kashi?Yecheng strike-slip belt in the eastern margin of Pamir salient,respectively.The analogue modeling results show that:(1)Both of the Kekeya?Hetian fold-and-thrust belt andKashi?Yecheng strike-slip belt in the eastern margin of Pamir salient were formed under compressive shearing.Strike-slip faults occurred within both of the belts,but the displacement of these strike-slip faults in the Kekeya?Hetianfold-and-thrust belt is less than that in the Kashi?Yecheng strike-slip belt;(2)The Kekeya?Hetian fold-and-thrust belt ismainly under the influence of compression stress with weaker shearing stress while the Kashi?Yecheng strike-slip belt ismainly under the influence of shearing stress with oblique compressive stress.The strike-slip faults are mainly locatedin the piedmont within these two belts.The effect of the strike-slip fault diminishes towards the front of the thrust belt(to the interior basin);(3)In the front of the boundary strike-slip faults(to the interior basin),the intersecting arc thrustfaults occurred successively along the shortening direction.These structural features demonstrated that the structuresevolved northwards in the eastern margin of Pamir salient;(4)The oblique compression does not necessarily result inhigh angle faults or vertical faults,whereas low-middle angle thrust faults with strike-slip displacement are also possible.Hence,more attention should be paid to such thrust faults during the structural analysis of seismic profiles in the easternmargin of Pamir salient(e.g.the structural belts in piedmont of western Tarim Basin).

关 键 词：帕米尔东缘 物理模拟 塔西南 斜向挤压 走滑构造 

分 类 号：P542[天文地球—构造地质学]