东秦岭南召-镇平地区早古生代花岗岩类锆石U-Pb年龄及地质意义  

LA-ICP-MS Zircon U-Pb Ages and Geological Significance of Early Paleozoic Granitoids in the Nanzhao-Zhenping Area,Eastern Qinling Orogenic Belt

作　　者：李开文 方怀宾[1] 刘坤[1] 郭君功[1] 赵焕 王小娟[1] LI Kai-wen;FANG Huai-bin;LIU Kun;GUO Jun-gong;ZHAO Huan;WANG Xiao-juan(Henan Institute of Geological Survey,Zhengzhou 450001,China;Henan Key Laboratory for Metal Mineral Ore-forming Geological Process and Utilization of Resource,Zhengzhou 450001,China)

机构地区：[1]河南省地质调查院,郑州450001 [2]河南省金属矿产成矿地质过程与资源利用重点实验室,郑州450001

出　　处：《矿物岩石地球化学通报》2019年第6期1091-1099,共9页Bulletin of Mineralogy, Petrology and Geochemistry

基　　金：中国地质调查局区域地质矿产调查项目(12120114027001,DD20160043)。

摘　　要：为了对秦岭造山带东段造山作用过程进行限定,对东秦岭早古生代花岗岩类进行了野外地质调查及年代学研究。结果表明,从早到晚,花岗岩类经历了由中性—酸性—碱性岩的正演变序列,岩石类型依次为石英闪长岩—花岗闪长岩—二长花岗岩类—正长花岗岩,LA-ICP-MS锆石U-Pb定年获得各类岩石的年龄分别为:(473.5±2.5)Ma,(435.2±2.4)Ma,(432.1±2.2)Ma和(418.0±2.9)Ma。不同岩性的岩体其野外地质特征明显不同,先后顺序清晰。结合区域资料初步认为,东秦岭早古生代大致经历了几个演化阶段:晚寒武世-中奥陶世板块俯冲阶段、晚奥陶世-中志留世板块碰撞阶段和晚志留世-早泥盆世后碰撞阶段。In order to assess the early Paleozoic tectonic process of the East Qinling Orogenic Belt,field geological survey together with LA-ICP-MS zircon U-Pb dating were carried out on the early Paleozoic granitoids in the East Qinling Orogenic Belt.Granitoids are composed of diorite,granodiorite,monzogranite and syenogranite,forming a normal magmatic evolution sequence(basic rocks-intermediate rocks-acid rocks-alkaline rocks).LA-ICP-MS zircon U-Pb dating results indicate the ages of quartz diorite,granodiorite,monzogranite and syenogranite are(473.5±2.5)Ma,(435.2±2.4)Ma,(432.1±2.2)Ma and(418.0±2.9)Ma,respectively.These rocks show different geological characteristics with clear geological contacts.Therefore,we propose that the Eastern Qinling Mountains had experienced three tectonic evolution stages at early Paleozoic:subduction stage from late Cambrian to Middle Ordovician,collision stage from late Ordovician to middle Silurian and post-collision stage from late Silurian to early Devonian.

关 键 词：早古生代 花岗岩类 LA-ICP-MS锆石U-Pb 东秦岭 

分 类 号：P588.12[天文地球—岩石学] P597[天文地球—地质学]