西藏工布江达县亚贵拉铅锌钼多金属矿床石英斑岩锆石SHRIMP定年及其地质意义  

SHRIMP U-Pb Dating of Zircon from Quartz Porphyry in the Yaguila Pb-Zn-Mo Deposit,Gongbujiangda County,Tibet and Its Geological Implication

作　　者：高一鸣[1] 陈毓川[2] 唐菊兴[3] 杜欣[4] 李新法[4] 高明[4] 蔡志超[4] 

机构地区：[1]中国地质科学院研究生部,北京100037 [2]中国地质科学院,北京100037 [3]中国地质科学院矿产资源研究所,北京100037 [4]河南省地质调查院,郑州450001

出　　处：《地质学报》2009年第10期1436-1444,共9页Acta Geologica Sinica

基　　金：国家科技支撑项目(编号2006BAB01A01);青藏高原专项项目(编号1212010818089);国家基础研究计划"973"项目(编号2002CB412607)资助的成果

摘　　要：采用SHRIMP微区U-Pb测年技术,对冈底斯成矿带东段工布江达县亚贵拉铅锌、钼矿区的石英斑岩岩体进行年代学研究,通过对3件含矿石英斑岩样品中单颗粒锆石56个样品点的分析,其206Pb/238U年龄范围在110.2±6.8～140.9±1.9Ma之间,3件样品206Pb/238U年龄加权平均值分别为128±1.0Ma(n=20,MSWD=1.3),129.3±1.3Ma(n=14,MSWD=1.12),127.8±1.1Ma(n=22,MSWD=1.4)。结合前人研究以及本次测年结果认为:①区内石英斑岩岩体侵位年龄在126.7～130.6Ma之间,属于燕山晚期;②亚贵拉铅锌、钼矿矿床属于斑岩型钼矿矽卡岩型-热液脉型铅锌铜银多金属矿床,而非晚石炭世—早二叠世的海底喷流沉积成因矿床;③亚贵拉-沙让矿集区矿床的形成得益于燕山晚期和喜马拉雅早期的岩体侵位,并与碰撞前(180～65Ma)及主碰撞期(65～41Ma)的岩浆活动关系密切,属于碰撞前和主碰撞期早期成矿。这一认识对冈底斯的区域找矿具有极其重要的意义。Located in Gongbuiiangda County, Tibet, the Yaguila Pb-Zn, Mo deposit is a porphyry Mo-skarn- hydrothermal vein type deposit, which belongs to the eastern part of the Gangdese belt. This study provides the high-precision magmatic zircon SHRIMP dating of the quartz porphyry from the Yaguila deposit. SHRIMP U-Pb dating analyses for 56 zircon grains from the quartz porphyry present ^206Pb/^238U concordant ages from 110.2±6.8 Ma to 140.9±1.9 Ma. The weighted mean ages of the three rocks are 128±1.0 Ma （n=20, MSWD=1. 3）, 129.3±1.3 Ma （n=14, MSWD=1. 12）, 127.8±1.1 Ma （n=22, MSWD=1. 4） respectively. Based on the former study, and the results of zircon dating mentioned above, it is proposed that： （1）Crystallization of the quartz porphyry occurred between 126.7-130.6 Ma, during the Late Yenshanian period. （2）The Yaguila-Sharang deposit is not a SEDEX type deposit but a porphyry Mo-skarn-hydrothermal vein type deposit. （4）The mineralization related to the crystallization of the quartz porphyry during the Late Yenshanian period to the early himalayan period. There are mineralization movements during main Indian-Asian collision period （41-65 Ma）in the Gangdese belt, which means a lot for the mineral resource prospecting of this area.

关 键 词：西藏 冈底斯 亚贵拉 沙让 斑岩钼矿 矽卡岩矿床 热液矿床 锆石SHRIMP U-Pb年龄 主碰撞期 

分 类 号：P597.3[天文地球—地球化学] P618.65[天文地球—地质学]