西准噶尔地区托里断裂晚第四纪构造变形  

GEOLOGICAL DEFORMATION OF THE TUOLI FAULT IN THE WEST JUNGGAR SINCE THE LATE QUATERNARY

作　　者：原浩东 李安[1,3] 黄伟亮 胡宗凯 左玉琦 杨晓平 YUAN Hao-dong;LI An;HUANG Wei-liang;HU Zong-kai;ZUO Yu-qi;YANG Xiao-ping(State Key Laboratory of Earthquake Dynamics,Institute of Geology,China Earthquake Administration,Beijing 100029,China;College of Geological Engineering and Surveying of Chang′an University,Key Laboratory of Western China Mineral Resources and Geological Engineering,Xi′an 710054,China;Xinjiang Pamir Intracontinental Subduction National Observation and Research Station,Beijing 100029,China)

机构地区：[1]中国地震局地质研究所,地震动力学国家重点实验室,北京100029 [2]长安大学,地质工程与测绘学院,西部矿产资源与地质工程教育部重点实验室,西安710054 [3]新疆帕米尔陆内俯冲国家野外科学观测研究站,北京100029

出　　处：《地震地质》2023年第1期49-66,共18页Seismology and Geology

基　　金：中国地震局地质研究所基本科研业务专项(IGCEA2115)资助。

摘　　要：受新生代印度-欧亚板块碰撞的远程效应影响,西准噶尔地区平行斜列的走滑断裂系统被重新激活。托里断裂作为其中重要的组成部分,获取其晚第四纪构造变形特征对于认识和理解天山以北区域的构造变形和地壳缩短吸收方式都具有重要意义。文中基于野外调查结果和无人机三维重建技术分析了托里断裂晚第四纪的构造变形特征,并利用光释光测年方法对托里断裂的地貌面期次进行定年,进而通过冲沟和阶地陡坎等标志性地貌的位错量和地貌年龄计算托里断裂的晚第四纪活动速率。研究结果表明:托里断裂由东、西2支分支断裂构成,均以左旋水平走滑为主。东支断裂使喀普舍克河T3和T2阶地分别产生了(89±31)m和(39±13)m的水平位错量,结合T3阶地(52.9±5.1)ka和T2阶地(23.4±1.5)ka的形成年龄,计算得到其活动速率约为(1.7±0.8)mm/a;西支断裂使铁斯巴汗河T2阶地产生了(34.0±6.8)m的水平位错量以及喀普舍克河T3阶地上最大为(37.5-4.1/+2.7)m的冲沟水平位错量,结合T2阶地(18.8±1.3)ka的形成年龄,计算得到其活动速率为(1.8+0.5/-1.3)mm/a。结合前人对塔城东断裂的研究结果分析认为,西准噶尔地区的平行左旋走滑断裂系统具有书斜构造模型的特点,并通过断裂系的平行走滑运动吸收了西准噶尔地区大部分挤压缩短量,在控制该区域SN向地壳缩短过程中发挥了重要作用。In the Cenozoic,under the influence of the collision of the India-Eurasia plate and the northward pushing after that,deformation occurred in the interior of the continent,and the crustal deformation is mainly absorbed by the thickening of the crust and the strike-slip movement of the fault.The GPS velocity field shows that the area north of Tianshan absorbs the shortening with a rate of~2mm/a.How the shortening with these rates is absorbed is a topic worthy of study.The West Junggar,located to the north of the Tianshan Mountains and developed with the inclined parallel strike-slip fault system is an important area of crustal shortening.The inclined parallel strike-slip fault system includes the east Tacheng Fault,Tuoli Fault and Daerbute Fault.Hence,the structural deformation of the Tuoli Fault in the late Quaternary is significant for understanding the structural deformation and crustal shortening absorption mode in the north of Tianshan Mountains.In this study,two branches were found extending along the Tuoli Fault in the direction of NE based on remote sensing image interpretation.Field investigation to the two branch faults shows that many marker landforms were dislocated in the study area,including gullies and terrace riser.The two faults cross through the terraces developed in the Kapusheke River and the Tiesibahan River in this area,forming offset terrace riser.Because the terrace riser is in the retained bank of the river,the upper-layer terrace model is used to calculate the fault’s slip rate.The gullies are mainly distributed on the T3 terrace of the Kapushek River on the west branch fault.The horizontal dislocation of these gullies ranges from 10m to 37.5m,and the largest horizontal dislocation is located in the No.8 gully,which is(37.5-4.1/+2.7)m.Since the actual value of the fault movement rate must be greater than the rate obtained by the sub-gully offset,we choose the maximum offset of the gully on the landform surface in calculating the slip rate.We used OSL(Optical Stimulated Luminescence)to da

关 键 词：西准噶尔 托里断裂 晚第四纪 活动速率 书斜构造 

分 类 号：P315.2[天文地球—地震学]