内蒙古莲花山铜矿区花岗闪长斑岩LA-ICP-MS锆石U-Pb年龄

LA-ICP-MS zircon U-Pb dating of granodiorite porphyry in the Lianhuashan copper deposit of Inner Mongolia and its geological implications

为了精确厘定莲花山铜矿的成矿时代,在前人研究的基础上,开展了与成矿关系密切的花岗闪长斑岩锆石U-Pb定年测定。实验结果共获得4组年龄数据,第1组有1个锆石,^206Pb/^238U年龄为343Ma±2Ma;第2组1个锆石,^206Pb/^238U年龄为264Ma±2Ma;第3组有1个锆石,^206Pb/^238U年龄为256Ma±2Ma;第4组有17个锆石,^206Pb/^238U年龄在240～249Ma之间,^206Pb/^238U年龄加权平均值为246.4Ma±1.2Ma（N=17）。结合所测锆石的CL图像特征,确定花岗闪长斑岩就位发生在晚二叠世—早三叠世。

On the basis of previous studies,this paper carried out zircon U-Pb dating for mineralization-associated granodiorite porphyry to further study its metallogenic epoch.Four groups of ages were obtained.The first group contains one zircon with ^206Pb/^238 U age of 343Ma±2Ma;the second group contains one zircon with ^206Pb/^238 U age of 264Ma±2Ma;the third group contains one zircon with ^206Pb/^238 U age of 256Ma±2Ma;the fourth group comprises 17 zircons,whose ^206Pb/^238 U ages vary from 240 Ma to 249 Ma,with a weighted mean ^206Pb/^238 U age of 246.4Ma±1.2Ma（N=17）.In conjunction with characteristics of CL imaging,the authors hold that the emplacement of granodiorite porphyry occurred between the Late Permian and Early Triassic.