西藏波龙铜矿区成矿流体来源示踪  

The source of ore-forming fluids in the Bolong copper mine area,Tibet

作　　者：周玉[1,2] 多吉[1,3] 温春齐[1] 费光春[1] 何阳阳[1] 

机构地区：[1]成都理工大学地球科学学院,四川成都610059 [2]中国地质科学院矿产综合利用研究所,四川成都610041 [3]西藏自治区地质矿产勘查开发局,西藏拉萨850000

出　　处：《中国矿业》2015年第3期76-80,共5页China Mining Magazine

基　　金：国土资源部公益性行业科研专项资助(编号:201011013);矿物学岩石学矿床学国家重点(培育)学科建设项目资助(编号:SZD0407)

摘　　要：波龙铜矿床是西藏地质五队近年来在青藏高原中部发现的最大的斑岩型矿床。为了查明波龙铜矿区成矿流体来源,对采自矿区的黄铁矿及石英流体包裹体样品进行了He、Ar同位素与气相成分测试。测试结果显示黄铁矿流体包裹体3 He/4 He分别为3.03和8.51,40 Ar/36 Ar为214.94和284.23,表明成矿流体可能来源于壳幔混源;石英包裹体气相成分以H2O为主,次为CO2,还有少量的N2、CH4、C2H6、H2S及Ar气体,部分样品中还含有O2成分,表明成矿流体中混有高氧逸度组分;结合矿区石英包裹体H-O同位素显示成矿流体以岩浆源为主、并混有大气成分分析,波龙铜矿区成矿流体应属壳幔混源,早期成矿流体以深源为主,晚期随着流体的演化有部分大气降水的加入。具高氧逸度特征的怒江洋壳俯冲板片携带大量成矿物质俯冲进入羌塘-三江复合板片南缘深部,熔融交代上覆地幔楔,发生壳幔混合,形成初始岩浆,在上升过程中混染下地壳物质,并受到深循环大气降水的影响最终侵位到上部地壳形成波龙铜矿床。The Bolong porphyry copper deposit was founded the largest copper deposits in central Tibet Plateau in recent years by No .5 Geological Party ,Tibet Bureau of Geology and Mineral Exploration and Development .In order to identify Source of Ore‐Forming Fluids in the Bolong copper mine and samples of fluid inclusions in pyrite and quartz form Copper Mine Area were Sampled to test their noble gas isotope or gas composition .Testing has shown that 3 He/4 He were 3 .03 and 8 .51 ,and 40 Ar/36 Ar were 214 .94 and 284 .23 ,it showed that ore‐forming fluid may be come from the crust‐mantle mixed source .Gaseous composition of fluid inclusion mainly composed of H 2 O ,followed by CO2 ,in addition to a small amount of N2 ,CH4 ,C2 H6 ,H2 S and Ar ,Portion of the sample composition also contains O2 ,it showed that ore‐forming fluids mixed with high oxygen fugacity component .Combined with H‐O isotopes of quartz inclusions that source was based with magma source and mixed with atmospheric composition ,thus we considered that ore‐forming fluids of the Bolong copper mine should be mixed with source of mantle and Crustal ,Early mineralization dominated deep source fluid ,and it mixed some atmospheric precipitation with the evolution of the fluid advanced .With high oxygen fugacity characteristics Nujiang oceanic crust subducted slab carried large amounts minerals melted and explained the overlying mantle wedge ,and occured crust‐mantle mixed ,＆amp;nbsp;formed the initial of magma ,Contaminated lower crust component during ascending ,and affected by deep‐cycle precipitation and emplaced into the upper crust to form the Bolong copper deposit finally .

关 键 词：稀有气体同位素 流体包裹体气相成分 波龙铜矿区 

分 类 号：P597.1[天文地球—地球化学] P61[天文地球—地质学]