新疆乌伦布拉克铜矿流体包裹体特征及含矿岩体年代学  

Fluid Inclusions and Geochronology of Wulunbulake Copper Deposit in Xinjiang

作　　者：孙万龙[1] 彭素霞[2] 白建科[2] 刘建朝[1] 王德明 邵博琪 李天石 Sun Wanlong;Peng Suxia;Bai Jianke;Liu Jianchao;Wang Deming;Shao Boqi;Li Tianshi(School of Earth Science and Resources,Chang'an University,Xi'an 710054,China;Xi'an Center of Geological Survey,China Geological Survey,Xi'an 710054,China;Regional Geological Survey Brigade No.2,Xinjiang Bureau of Geology and Mineral Resources,Changji 831100,China;School of Earth Sciences and Resources,China University of Geosciences,Beijing 100083,China)

机构地区：[1]长安大学地球科学与资源学院,陕西西安710054 [2]中国地质调查局西安地质调查中心,陕西西安710054 [3]新疆地矿局第二区域地质调查大队,新疆昌吉831100 [4]中国地质大学地球科学与资源学院,北京100083

出　　处：《地球科学》2018年第12期4475-4489,共15页Earth Science

基　　金：陕西省自然科学基金项目(No.2018JM4001);中国地质调查局地质矿产调查评价项目(No.DD20160006)

摘　　要：乌伦布拉克铜矿位于新疆东准噶尔野马泉-琼河坝铜多金属成矿带中,其矿床成因和成矿时代存在较大争议,从流体包裹体和锆石U-Pb定年等方面做了研究探讨.矿床主要发育富液相包裹体,成矿流体为低温(136.9~224.5℃)、低盐度(1.7%~5.6%NaCleqv.)、低密度(0.97~1.01g/cm^3)流体,估算的成矿压力为2.76×10^7~4.49×10^7Pa,对应的成矿深度为1.04~1.95km,属于浅成矿床.激光拉曼探针测试结果表明流体液相组分主要为水,气相组分除水蒸气外,还含有一定量CH4、N2和H2.锆石U-Pb测年结果显示含矿石英闪长岩年龄为440.5±3.3Ma,不含矿石英斑岩年龄为419.7±3.3Ma,表明研究区至少经历了2期岩浆活动,成矿作用从早志留世就已开始.矿床由内向外发育典型的“斑岩型”蚀变分带(强硅化带-钾化带-绢英岩化带-青磐岩化带),表明乌伦布拉克铜矿为斑岩型铜矿,形成于志留纪古亚洲洋向南俯冲的岛弧环境.东准噶尔甚至新疆北部地区在志留纪处于岛弧环境,该时期的岩浆岩带是形成和寻找斑岩型铜矿的有利地区.Wulunbulake copper deposit is located at the north-western segment of the Yemaquan-Qiongheba Cu-polymetallic metallogenic belt, East Junggar, Xinjiang. However, its genetic type and mineralizing age has been debated. This study presents new results on fluid inclusions and zircon U-Pb dating to precisely constrain the type and time of mineralization. The dominant fluid inclusions in Wulunbulake copper deposit are liquid-rich type, with low homogenization temperature (136.9- 224.5 ℃), low salinity (1.7%~5.6% NaCl eqv.) and low density (0.97-1.01 g/cm^3), the mineralizing pressure is 2.76×10^7- 4.49×10^7Pa and the corresponding depth is 1.04-1.95 km. The laser Raman spectroscopy results indicate that the ore-forming fluids consist of H2O, CH4, N2, H2. Zircon U-Pb dating results show that the formation age of ore-bearing quartz diorite and quartz porphyry is 440.5±3.3 Ma, and 419.7±3.3 Ma, respectively, indicating that there had experienced two-stage magmatic activities from Early Silurian. From the interior to the outer part of the deposit, there exist typical alteration zonation characteristics of porphyry deposits (silica alternation-potassic alternation-phyllic alternation-propylitization), and the geochemical characteristics of ore-bearing indicate that they were most possibly formed in arc setting. Its genetic type should be typical porphyry copper deposit and related to the southward subduction of the Paleo-Asian oceanic crust in the Early Silurian period. The East Junggar even northern Xinjiang was in the island arc environment in the Silurian, and the magmatic zone is a potential area for formation and prospecting of porphyritic Cu deposit.

关 键 词：流体包裹体 锆石U-Pb定年 斑岩型铜矿 东准噶尔 地质年代学 

分 类 号：P53[天文地球—古生物学与地层学]