西秦岭北缘新阳—元龙韧性剪切带中花岗质糜棱岩黑云母^(40)Ar-^(39)Ar年龄及地质意义  

Biotite ^(400Ar-^(39)Ar Ages of Granitic Mylonite at the Xinyang-Yuanlong Ductile Shear Zone in the North Margin of West Qinling and Their Geological Significance

作　　者：丁仨平 裴先治[1] 李勇[1] 李瑞保[1] 李佐臣[1] 冯建赟[1] 孙雨[1] 张亚峰[1] 

机构地区：[1]长安大学西部矿产资源与地质工程教育部重点实验室,长安大学地球科学与资源学院,西安710054

出　　处：《地质学报》2009年第11期1624-1632,共9页Acta Geologica Sinica

基　　金：国家自然科学基金项目(编号40972136;40572121);教育部科学技术研究重点项目(编号104175);中国地质调查局地质调查项目(编号200013000154)资助的成果

摘　　要：西秦岭北缘新阳—元龙大型韧性剪切带是分划西秦岭造山带与祁连造山带的区域主构造边界,通过对其物质组成和构造特征的研究,结合两侧不同(洋-陆)构造环境下各类地质体的研究成果,重点对剪切带内花岗质糜棱岩中黑云母单矿物进行了40Ar-39Ar定年研究。在新阳镇和元龙北剪切带中分别获得(347.95±2.17)Ma(MSWD=1.89)和(351.70±1.72)Ma(MSWD=0.80)的坪年龄,分析确定其应为黑云母的冷却年龄,表明变形时代应在早石炭世早期之前;反映了最晚在早石炭世早期,该剪切带已横切秦岭与祁连造山带并发生强烈的右行走滑构造拼贴作用。The Xinyang-Yuanlong ductile shear zone in the north margin of West Qinling is the main tectonic boundary which partitions the West Qinling orogenic belt from the Qilian Orogenic belt. Their material composition and tectonic characteristics were studied in this study combined with the study results of various blocks in different tectonic settings （ocean continent） of both side. This study also focused on ^40Ar-^39Ar dating of the biotite from granitic mylonite in the shear zone and yielded plateau ages of 347.95±2.17Ma （MSWD=1. 89） and 351.70±1.72Ma （MSWD=0.80）for Xinyang Town and the shear zone of northern Yuanlong respectively. They are identified as cooling ages of the biotites, indicating that the time of deformation should earlier than the early period of Early Carboniferous. The research shows that it was at least at the early Carboniferous that the shear zone cut across the Qinling orogenic belt and the Qilian Orogenic belt and underwent intense dextral strike slipping and tectonic matching in the early period of Early Carboniferous at the latest,.

关 键 词：韧性剪切带 花岗质糜棱岩 黑云母40Ar-39Ar定年 西秦岭北缘 

分 类 号：P578.959[天文地球—矿物学] P597.3[天文地球—地质学]