阿尔金断裂带东西两端构造转换与扩展过程:从三联点谈起  

Tectonic transition and extension at the eastern and western ends of the Altyn Tagh fault:insights from triple junctions

作　　者：衣可心 Marc Jolivet 郭召杰[1] YI Kexin;JOLIVET Marc;GUO Zhaojie(Key Laboratory of Orogenic Belts and Crustal Evolution,School of Earth and Space Sciences,Peking University,Beijing 100871,China;Géosciences Rennes–UMR CNRS 6118,Universitéde Rennes,Rennes 35700,France)

机构地区：[1]北京大学地球与空间科学学院造山带与地壳演化教育部重点实验室,北京100871 [2]Géosciences Rennes–UMR CNRS 6118,Universitéde Rennes,Rennes 35700,France

出　　处：《地质力学学报》2025年第1期24-38,共15页Journal of Geomechanics

基　　金：国家自然科学基金重点项目(41930213)。

摘　　要：阿尔金断裂带作为青藏高原北缘的关键构造边界,其演化历史和构造转换机制对理解青藏高原的生长极为重要。阿尔金断裂带不同分段的构造环境与演化历程不同,其各自与祁连山造山带和祁曼塔格-东昆仑断裂带的构造转换研究也仍有不足之处。三联点分析是板块构造学中的重要分析方法,速度三角形反映了断裂属性,三联点稳定性则从运动学角度揭示了断裂的演化方向和历程。综合地质、地貌与地震资料,系统分析了阿尔金断裂带中段与东西段代表性的肃北与吐拉三联点的构造特征与活动历史;并借助三联点稳定性准则,构建了这2个三联点的演化模型。研究结果表明,野马河-大雪山断裂与祁曼塔格-东昆仑断裂带启动,不稳定三联点形成并向稳定三联点转化,促使阿尔金断裂带“截弯取直”,并在此基础上提出了分段破裂-双向扩展模型。这一结果为理解青藏高原北缘复杂的构造演化历史提供了新的视角。[Objective]The Altyn Tagh fault(ATF)is the largest left-lateral strike-slip fault on the northern margin of the Qinghai-Tibet Plateau,extending for about 1600 km.It accommodates a considerable portion of the India-Eurasia convergence and is widely regarded as a key tectonic boundary influencing the plateau’s uplift and outward growth.However,its mode of propagation remains debated.Resolving this debate requires clarifying how the ATF evolved into its present configuration and how it connects with adjacent structures such as the Qilian orogenic belt and the QimantaghEastern Kunlun fault.In this study,we use the concept of triple junctions to investigate key transition zones at the eastern and western ends of the ATF—namely,the Subei and Tula triple junctions—to shed light on the fault’s Cenozoic segmented rupture and bidirectional extension.[Methods]Triple junction analysis,a fundamental method in plate tectonics,is utilized to assess fault properties and fault stability from a kinematic perspective.Additionally,GPS data and seismic source mechanism solutions are analyzed to characterize the current kinematic behaviors and movement directions of the faults.[Results](1)Transition between ATF and Qilian orogenic belt:Subei triple junction.The central segment of the ATF was the earliest to become active during the Cenozoic,generating a compressional horsetail splay on its eastern termination.The Danghe Nanshan fault and Yemahe-Daxueshan fault emerged as part of this horsetail splay.As left-lateral strike-slip motion on the ATF accelerated in the Miocene,large offsets developed between the Tarim,Qaidam,and Qilian blocks,giving rise to a triple junction near Subei.Initially,this triple junction was unstable,and the Qilian block experienced extensional strain relative to the Tarim block,indicating a local stretching environment.To achieve stability,the ATF progressively“straightened”eastward,ultimately supplanting the Yemahe-Daxueshan fault.Its western segment was reoriented to run parallel to the ATF,while

关 键 词：阿尔金断裂带 青藏高原北缘 三联点 构造转换 祁连山造山带 

分 类 号：P542[天文地球—构造地质学]