内蒙古大井铜多金属矿床脉岩LA-ICP-MS锆石U-Pb定年及成矿时代  

LA-ICP-MS zircon U-Pb dating of dikes in the Dajing copper-polymetallic deposit and a discussion on the metallogenic epoch

作　　者：刘铭涛[1] 刘建明[2] 薛春纪[3] 陈向平 陈志国[1] 冯宝山[1] LIU Mingtao;LIU Jianming;XUE Chunji;CHEN Xiangping;CHEN Zhiguo;FENG Baoshan(Tianjin North China Geological Exploration Bureau, Tianjin 300170,China;Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China;State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100083, China)

机构地区：[1]天津华北地质勘查局,天津300170 [2]中国科学院地质与地球物理研究所,北京100029 [3]中国地质大学地质过程与矿产资源国家重点实验室,北京100083

出　　处：《地质通报》2019年第8期1306-1313,共8页Geological Bulletin of China

基　　金：地方政府委托中国科学院地质与地球物理研究所项目《赤峰市有色金属成矿规律研究》

摘　　要：内蒙古林西县大井矿床是与次火山岩有关的热液脉型矿床,矿体受NW向、NWW向断裂控制,产出在二叠系林西组中。用LA-ICP-MS技术,测得成矿前的霏细岩脉和安山玢岩脉中的锆石206Pb/238U年龄分别为164.1±0.8Ma(MSWD=0.60,n=16)和253.8±1.1Ma(MSWD=0.96,n=14)。其中霏细岩锆石年龄表明,其形成可能与西伯利亚板块和蒙古-华北板块之间的鄂霍茨克洋碰撞造山有关;安山玢岩可能与华北板块与西伯利亚板块碰撞造山有关。通过成矿前脉岩的锆石年龄,可以限定大井矿床的成矿时代晚于164Ma。结合前人研究结果,推测大井铜多金属矿床的形成主要受控于晚侏罗世-早白垩世岩浆活动。The Dajing deposit was previously regarded as a magmatic hydrothermal type deposit.The orebodies are controlled by the NW-and NWW-trending faults and occur in Permian Linxi Formation. The zircon samples collected during the research were dated by using LA-ICP-MS zircon U-Pb method, and the authors obtained the following results: the zircon U-Pb ages are 164.1±0.8 Ma(MSWD=0.60, n=16)and 253.8±1.1 Ma(MSWD=0.96, n=14)for felsite dikes and andesite porphyry dikes, respectively.Felsite dikes were formed in a collisional setting probably related to the closure of Mongolia-Okhotsk Ocean and post collision,while andesite porphyry dikes were formed in a tectonic setting possibly related to the collision between Siberian Plate and North China Plate. Based on the zircon U-Pb ages of dikes obtained, the authors have reached the conclusion that the ore-forming process of the Dajing polymetallic deposit occurred later than 164 Ma. The most intense volcanic-magmatic activities of the Da Hinggan Mountains took place during Middle Yanshanian period. It is therefore held that the ore-forming process of the Dajing polymetallic deposit occurred approximately in Late Jurassic-Early Cretaceous.

关 键 词：大井 LA-ICP-MS锆石U-PB定年 成矿年代 晚侏罗世-早白垩世 霏细岩 安山玢岩 

分 类 号：P618.41[天文地球—矿床学] P597[天文地球—地质学]