广西富贺钟钨锡多金属矿集区稀有气体同位素特征及其地质意义  

Isotopic Characteristics of Noble Gases of the Fuchuan-Hezhou-Zhongshan W-Sn-polymetallic Ore Concentration Area in Northeastern Guangxi and Their Geological Significance

作　　者：蔡明海[1] 彭振安[1] 长尾敬介[2] 王显彬[1] 郭腾飞[1] 刘虎[1] 

机构地区：[1]广西大学资源与冶金学院,广西南宁530004 [2]东京大学大学院理学系研究科地壳化学实验室

出　　处：《地球学报》2013年第3期287-294,共8页Acta Geoscientica Sinica

基　　金：广西科技厅自然基金项目"广西富贺钟钨锡矿集区壳幔成矿作用研究"(编号:桂科自0728024)资助

摘　　要：桂东北富贺钟地区是广西重要的有色金属基地之一,在姑婆山复式岩体的西南缘产出有新路、水岩坝和珊瑚3个主要钨锡多金属矿田。本文对不同矿田典型矿床分别开展了稀有气体同位素研究,根据黄铁矿流体包裹体He、Ar、Ne同位素组成,进一步讨论了区内钨锡成矿流体来源和壳-幔成矿作用过程。结果表明,黄铁矿流体包裹体3He/4He=0.53～4.53Ra、40Ar/36Ar=315.58～600.55、38Ar/36Ar=0.18688～0.19102、20Ne/22Ne=9.737～9.848、21Ne/22Ne=0.0291～0.0304,显示成矿流体为地壳流体、幔源流体和饱和大气水的混合物,成矿过程中有地幔物质的加入,地幔He约占8.7%～75.7%。结合区内成岩、成矿的测年资料及岩石成因等综合分析认为,区内中生代发生了多期次壳-幔相互作用,且作用强度经历了强→弱→强的演化过程,分别导致了姑婆山岩体主体岩性(165～160Ma)和晚期细粒花岗岩(154～151Ma)的侵位,以及钨锡多金属成矿作用(136～100Ma),成矿与晚期的细粒花岗岩同位但不同时。Located at the conjunction of Fuchuan County, Hezhong City and Zhongshan County in northeastern Guangxi, the Fuchuan-Hezhou-Zhongshan W-Sn-polymetallic ore concentration area is one of the important nonferrous metal producing areas in Guangxi. It consists of three W-Sn-polymetallic orefields （Xinlu, Shuiyanba and Sanhu） lying on the southwestern margin of the Guposhan composite granite mass. In order to study the material sources and metallogenic mechanism of W-Sn-polymetallic deposits in the Fuchuan-Hezhou-Zhongshan ore concentration area, the authors analyzed the noble gases isotopic components of fluid inclusions in pyrite from the Baimianshan Sn-Zn deposit, the Shuiyanba W-Sn deposit and the Changyingling W-Sn deposit. The results indicate that 3He/4He ratios are 0.53-4.53 Ra, 4~Ar/36Ar ratios are 315.58-600.55, 38Ar/36Ar ratios are 0.18688-0.19102, 2Ne/22Ne ratios are 9.737-9.848, and 21Ne/22Ne ratios are 0.0291-0.0304. The data obtainedsuggests that the ore-forming fluid was mixed proportion of He derived from the mantle was Guposhan granites and mineralization as with meteoric water, mantle fluid and crustal fluid, and the 8.7%-75.7%. A synthetic analysis of the dating results of the well as the genesis of granites shows that the Fuchuan-Hezhou-Zhongshan ore concentration area experienced poly-phase crust-mantle interaction in Mesozoic, and the crust-mantle interaction underwent the evolution from high intensity through low intensity to high intensity, resulting in the magmatic emplacement of Guposhan granites （165-160 Ma） and late fine-grained granite （154-151 Ma） as well as mineralization of the W-Sn-polymetallic deposit （136-100 Ma） respectively. The metallogenic epoch was later than that of late fine-grained granite, whereas the W-Sn-polymetallic ore bodies occurred in the same place as the late fine-grained granite.

关 键 词：成矿流体 稀有气体同位素 钨锡矿床 广西富贺钟地区 

分 类 号：P595[天文地球—地球化学]