都龙锡锌矿床锡石和锆石U-Pb年代学：滇东南白垩纪大规模花岗岩成岩-成矿事件  

U-Pb geochronology of cassiterite and zircon from the Dulong Sn-Zn deposit:Evidence for Cretaceous large-scale granitic magmatism and mineralization events in southeastern Yunnan province,China.

作　　者：刘玉平[1] 李正祥[2] 李惠民[3] 郭利果[4] 徐伟[1] 叶霖[1] 李朝阳[1] 皮道会[1] 

机构地区：[1]中国科学院地球化学研究所矿床地球化学国家重点实验室,贵阳550002 [2]西澳大学大地构造专门研究中心 [3]中国地质调查局天津地质调查中心,天津300170 [4]中国科学院广州地球化学研究所

出　　处：《岩石学报》2007年第5期967-976,共10页Acta Petrologica Sinica

基　　金：国家自然科学基金(批准号:4302026);中国科学院2003年度留学基金(编号:2003023)和TSRC研究基金资助

摘　　要：都龙锡锌矿床是我国最大的锡石硫化物矿床之一。由于缺少可靠的年代学数据,对该矿床的成因尚存在较大争议。本文报道了利用锡石和锆石U-Pb法,首次获得的都龙锡锌矿床及相关的燕山晚期老君山花岗岩的年龄。其中,锡石TIMS法^(206)Pb/^(238)U年龄加权平均值为79.8±3.2Ma(MSWD=3.16),(238)U/^(204)Pb-^(206)Pb/^(204)Pb等时线年龄为82.0±9.6Ma (MSWD=4.81);隐伏花岗岩的锆石SHRIMP法^(206)Pb/^(238)U年龄加权平均值为92.9±1.9Ma(N=10,MSWD=0.71),花岗斑岩的锆石SHRIMP法^(206)Pb/^(238)U年龄加权平均值为86.9±1.4Ma(N=9,MSWD=3.70),表明锡(铜)矿化主要与晚白垩世岩浆热液活动有关。结合个旧、白牛厂两个超大型矿床和相关花岗岩体的年代学资料,指示滇东南地区于白垩纪存在以锡矿化为特色的大规模花岗岩成岩-成矿事件,可能与晚中生代以来华南地块岩石圈伸展有关。The Dulong Sn-Zn deposit is one of the largest cassiterite-sulfide deposits in China. There are different opinions regarding the genesis of this deposit, partly due to the lack of reliable geochronological data. We report here results of the first attempt to determine the magmatic and mineralization ages of this deposit and related late-Yanshanian granites through U-Pb dating of cassiterite and zircon. Four cassiterite samples from the Manjiazhai section yields a means ^206Pb / ^238 U age of 79.8 ±3.2Ma（ MSWD = 3.16）, and a ^238 U/^204pb-^206 Pb/^204pb isochronal age of 82.0 ±9.6Ma（ MSWD =4.81 ） using the TIMS U-Pb method. Zircon from a concealed granite at the Manjiazhai section yielded a means ^206Pb / ^238 U age of 92.9 ± 1.9Ma（ N = 10, MSWD = 0.71 ）, and zircon derived from a granitic-porphyry outcrop at the Tongjie section yielded a means ^206Pb /^238 U age of 86.9 ± 1.4Ma（ N = 9, MSWD = 3.70 ）, both obtained using the SHRIMP U-Pb method. These ages suggest that the tin （copper） mineralization in the Dulong Sn-Zn deposit was mainly related to the late Cretaceous magmatic hydrothermal events. The geochronological data of the Gejiu （Sn） and the Bainiuchang （Ag） super-large deposits and related Yanshanian granites indicate that there was a large-scale granitic magmatism and mineralization event during the Cretaceous in southeastern Yunnan, which might have been related to the lithospheric extension of the South China Block in late Mesozoic.

关 键 词：锡石 锆石 U-PB年龄 白垩纪 成岩-成矿事件 都龙锡-锌矿床 滇东南 

分 类 号：P611.1[天文地球—矿床学] P597.3[天文地球—地质学]