北阿尔金断裂晚第四纪活动构造特征  

LATE QUATERNARY ACTIVE TECTONICS OF THE NORTH ALTYN FAULT

作　　者：叶雨晖 吴磊[1] 王依平 楼谦谦[2] 陈力琦[3] 高石宝 林秀斌[1] 程晓敢[1] 陈汉林[1] YE Yu-hui;WU Lei;WANG Yi-ping;LOU Qian-qian;CHEN Li-qi;GAO Shi-bao;LIN Xiu-bin;CHENG Xiao-gan;CHEN Han-lin(Zhejiang Key Laboratory of Geoscience Big Data and Deep Earth Resources,School of Earth Sciences,Zhejiang University,Hangzhou 310027,China;The Third Geological Brigade of Zhejiang Province,Jinhua 321001,China;Information Center of Department of Land and Resources of Zhejiang Province,Hangzhou 310007,China)

机构地区：[1]浙江大学地球科学学院,浙江省地学大数据与深部资源重点实验室,杭州310027 [2]浙江省第三地质大队,金华321001 [3]浙江省国土资源厅信息中心,杭州310007

出　　处：《地震地质》2022年第2期297-312,共16页Seismology and Geology

基　　金：国家自然科学基金(41972218,41772203)资助。

摘　　要：位于青藏高原和塔里木盆地之间的北阿尔金断裂是青藏高原向N扩展的重要边界条件,目前对其新生代以来的运动学特征还存在较大争议。文中利用DEM数据提取了穿过北阿尔金断裂的18条河流及相关汇水盆地的地貌信息,分析了河流平、纵剖面的形态、标准化河流长度坡度指数(SLK)、标准化河流陡峭指数(K_(sn))以及汇水盆地面积-高程曲线和积分(HI)等多个构造地貌指标参数,以研究北阿尔金断裂晚第四纪以来的活动性和活动方式。结果表明,北阿尔金断裂西段的河流纵剖面和汇水盆地面积-高程曲线呈上凹型,河流纵剖面上发育较多小规模的裂点,SLK、K_(sn)和HI值相对较低。与之相反,其东段的河流纵剖面大都呈上凸型和平直型,在北阿尔金断裂上盘发育较大规模的河流裂点,对应较高的SLK和K_(sn)值;面积-高程曲线形态以S型和上凸型为主,HI值也相对较大。上述地貌指标反映北阿尔金断裂东段的地貌活动性较西段更强,推测为东段正好位于南阿尔金断裂阿克图受阻双弯曲北侧,受其强烈侧向挤压所致。此外,河流穿过北阿尔金断裂没有发生系统的左旋位错,新发现的一条错断晚第四纪冲积扇的前锋断裂也呈现出典型的逆冲特征,表明北阿尔金断裂在晚第四纪以来以逆冲运动为主。结合前人的研究结果推测,北阿尔金断裂在晚新生代存在从走滑向逆冲的构造转换,且与南阿尔金断裂之间存在密切的相互作用。The~1600 km long,left-reverse strike-slip active Altyn Tagh fault system defines the northern edge of the Tibetan plateau,and serves as an important tectonic boundary in models describing the northward expansion of the plateau.The Altyn Tagh fault system has complex geometries,and consists mainly of the left-lateral South Altyn Fault to the south,the left-reverse or reverse-dominated North Altyn Fault to the north,and the intervening Altyn Shan.Most of the existing studies focus on the more active South Altyn Tagh Fault,but few has paid attention to the North Altyn Fault,which separates the Tarim Basin to the north from the Altyn Shan to the south,and figures importantly in understanding the tectonic evolution of the entire fault system.The kinematics of the North Altyn Fault in the Cenozoic remains disputed in whether it is a left-reverse or reverse-dominated fault.Herein,we used tectonic geomorphology analysis to systematically study the characteristics of active tectonics on the North Altyn Fault in the Quaternary.There are dozens of rivers in the Altyn Shan between the South Altyn Tagh Fault and North Altyn Fault,the majority of which originate near the South Altyn Tagh Fault and flow northward across the North Altyn Fault into the Tarim Basin.These rivers contain abundant information about the Quaternary tectonic activity of the North Altyn Fault.We used SRTM DEM data to extract the geomorphic features of 18 rivers and related catchment basins flowing across the North Altyn Fault.Geomorphic index,such as river longitudinal profiles,standardized river length-gradient index(SLK),normalized river steepness index(K_(sn)),area-elevation curves and their integrals(HI)of catchment basins,are analyzed.The conclusions are drawn as follows.The geomorphological indexes show that the eastern part of the North Altyn Fault is geomorphologically more active than the western part.Along the western part of the North Altyn Fault,the river longitudinal profile and the area-elevation curves of the corresponding catchment basins

关 键 词：阿尔金断裂系 水系特征 地貌分析 走向变化 运动学转变 

分 类 号：P315.2[天文地球—地震学]