辽北清原大孤家韧性剪切带变形特征、变形时代及动力学背景  

Deformation characteristics,deformation age and dynamic background of Dagujia ductile shear zone in Qingyuan,northern Liaoning Province

作　　者：宋志伟 赵佳奇 梁琛岳[1,2] SONG Zhiwei;ZHAO Jiaqi;LIANG Chenyue(College of Earth Sciences,Jilin University,Changchun 130061,Jilin,China;Key Laboratory of Mineral Resources Evaluation in Northeast Asia,Ministry of Natural Resources,Jilin University,Changchun 130061,Jilin,China)

机构地区：[1]吉林大学地球科学学院,吉林长春130061 [2]吉林大学东北亚矿产资源评价自然资源部重点实验室,吉林长春130061

出　　处：《地质通报》2024年第12期2256-2271,I0007-I0013,共23页Geological Bulletin of China

基　　金：国家重点研发计划项目《东亚俯冲陆缘的构造变形响应与转换》(编号:2022YFF0800401-2);国家自然科学基金项目《东北地区山弯构造研究》(批准号:42130305)。

摘　　要：辽北清原地区位于华北克拉通北缘东段,发育大规模强变形花岗质岩石,是进一步研究中生代燕山运动和东北地区多构造体系叠加、转换过程的重要窗口。通过详细的宏微观构造解析、有限应变测量、石英EBSD组构分析和锆石U−Pb测年,厘定了区域内大孤家韧性剪切带的变形特征、变形时代和动力学背景。结果显示,大孤家韧性剪切带发育走向NW―SE的构造面理和倾伏向SE的矿物拉伸线理,整体具有NW向左行走滑剪切特点。岩石变形温度较高,介于550~650°C之间。剪切带内花岗质岩石主要形成于中生代多期次岩浆活动,结合区域构造年代学资料,限定剪切带变形时代为晚侏罗世末—早白垩世初,为燕山运动B幕在辽北地区的局部响应。古太平洋板片俯冲导致的区域断裂带重新活化是大孤家韧性剪切带形成的主要原因。The Qingyuan area in northern Liaoning Province is located in the eastern segment of the northern margin of the North China Craton,with large−scale strongly deformed granitic rocks.It is an important window to further study the Mesozoic Yanshanian movement and the superposition and transformation of multiple tectonic regimes of NE China.In this paper,the deformation characteristics,age and dynamical background of the regional Dagujia ductile shear zone are determined by detailed macro−and micro−structure analysis,finite strain measurements,quartz EBSD fabric and zircon U−Pb dating.The results show that the Dagujia ductile shear zone develops NW−SE−trending foliations and SE−plunging mineral stretching lineations,with a NW−trending sinistral strike−slip shear characteristics.The deformation temperatures of the rocks are relatively high,ranging between 550°C and 650°C.The granitic rocks in the shear zone primarily formed in Mesozoic multi−stage magmatism.Combined with the regional tectonic chronology data,the deformation age of the shear zone is the latest Late Jurassic to earliest Early Cretaceous,reflecting the local response of the Yanshanian Movement B−episode in the northern Liaoning Province.The Reactivation of regional fault zones caused by the subduction of the Paleo−Pacific Plate is the main reason for the formation of the Dagujia ductile shear zone.

关 键 词：辽北地区 构造解析 锆石U−Pb年龄 燕山运动 古太平洋板块 

分 类 号：P54[天文地球—构造地质学] P597.3[天文地球—地质学]