青藏高原东缘安宁河断裂带中-新生代构造变形及其磁组构特征  

Meso-cenozoic structural deformation and magnetic fabric characteristics of Anninghe fault belt at eastern Margin,Tibetan Plateau

作　　者：陈应涛[1] 余文鑫 张欢 杨秉正 李晗 艾卉卉 CHEN Yingtao;YU Wenxin;ZHANG Huan;YANG Bingzheng;LI Han;AI Huihui(College of Geology and Environment,Xi’an University of Science and Technology,Xi’an 710054,China)

机构地区：[1]西安科技大学地质与环境学院,陕西西安710054

出　　处：《西安科技大学学报》2021年第1期94-103,共10页Journal of Xi’an University of Science and Technology

基　　金：国家自然科学基金项目(41602212);中国博士后科学基金面上项目(2019M653694);陕西省自然科学基础研究计划资助项目(2019JM-126);西安科技大学博士科研启动金项目(2017QD007)联合资助。

摘　　要：安宁河断裂带是青藏高原东缘大型走滑断裂系鲜水河-小江断裂系重要组成部分,演化历史悠久,构造变形复杂。为了进一步理清青藏高原东缘安宁河断裂带中-新生代构造变形,文中通过详细的野外构造观察与解析并结合构造岩磁组构对安宁河断裂带进行精细的构造变形研究,厘定了安宁河断裂中-新生代构造变形序列及其变形特征。结果表明中生代安宁河断裂带先后经历了印支晚期NEE-SWW向挤压作用下的早期具有左行走滑特征的韧性剪切和晚期韧-脆性密集劈理化构造变形过程以及晚中生代近E-W向挤压作用下形成的低角度韧-脆性剪切三期构造变形过程;构造岩磁组构样品的平均磁化率具有强、弱磁化率2种特征,且构造岩具有磁面理较磁线理发育的特征,磁化率椭球体以压扁型为主,构造强应变特征明显;最小磁化率主轴呈NEE-SWW向,即中生代早期的韧脆性变形受到了NEE-SWW向的挤压作用,但运动学分析结果反映出了后期叠加改造的特征。新生代安宁河断裂带整体经历了NWW-SEE向挤压作用下以左行走滑为主的具有自西向东扩展特征的三幕挤压走滑和两幕斜张走滑构造变形过程,奠定了安宁河断裂带现今两堑夹一垒的构造地貌。这为深入认识和恢复川滇南北构造带及其青藏高原东缘的形成演化过程奠定了基础。Anninghe fault belt one of the most activities fault belts inside China's Mainland today,is an important constituent of Xianshuihe-Xiaojiang fault system on the eastern Margin of the Tibetan Plateau.In order to clarify the structural deformation of Anninghe fault belt in the Meso-Cenozoic,the intensive structural deformation of the Anninghe fault belt was studied based on the detailed field structure observation and analysis combined with the tectonites magnetic fabric.Results show that the Anninghe fault belt underwent three periods deformation in the Mesozoic:one is the left-lateral slip ductile shearing deformation process under the NEE-SWW pressure force in the late indosinian and the late ductile-brittle dense cleavage process,and the other is low angle brittle ductile shear deformation process under the E-W pressure force in the late Mesozoic.The tectonites fall into two groups,strong and weak average susceptibility,respectively.The magnetic foliation prevails over magnetic lineation indicating that magnetic susceptibility ellipsoid is oblate with strong strain structural characteristics.The minimum susceptibility principal axis is NEE-SWW direction,that is,the ductile-brittle deformation in the early Mesozoic has received NEE-SWW direction compression,but the result of kinematics analysis shows the characteristics of superimposition and transformation of later structures.In the Cenozoic,the Anninghe fault belt is characterized by the left-lateral slip,and underwent three periods extrusion strike-slips and two periods diagonal strike-slip deformation under the NWW-SEE pressure force.The tectonic landform that is a horst caught with two grabens today has been established by the deformation process in the Cenozoic.This understanding has laid a foundation for the deep understanding and recovers the formation and evolution of the Sichuan-Yunnan north-south tectonic belt and eastern margin of the Tibetan Plateau.

关 键 词：安宁河断裂带 构造变形 构造解析 磁组构 青藏高原东缘 

分 类 号：P545[天文地球—构造地质学]