桂西北丹池成矿带He、Ar同位素特征及其矿床成因指示  

He and Ar isotope characteristics and their genetic implications for the Sn-polymetallic deposits in the Danchi metallogenic belt,northwestern Guangxi

作　　者：蔡明海 李晔 彭振安 胡志戍 胡鹏飞 肖俊杰 CAI Minghai;LI Ye;PENG Zhenan;HU Zhishu;HU Pengfei;XIAO Junjie(School of Resources,Environment and Materials,Guangxi University,Nanning530004,China)

机构地区：[1]广西大学资源环境与材料学院,广西南宁530004

出　　处：《地质学报》2021年第12期3758-3767,共10页Acta Geologica Sinica

基　　金：广西自然科学基金项目(编号2020GXNSFAA159128)资助的成果。

摘　　要：桂西北丹池成矿带是我国南方重要的有色金属矿业基地。本文对成矿带内芒场矿田马鞍山Pb-Zn矿和大山Sn-Zn矿、大厂矿田铜坑Sn多金属矿、五圩矿田箭猪坡Pb-Zn多金属矿等4个主要矿床矿石黄铁矿流体包裹体He、Ar同位素进行了研究。结果表明,丹池成矿带内典型矿床成矿流体的^(3)He/^(4)He=0.79~5.32 Ra,介于地壳流体(0.01~0.05 Ra)与地幔流体(6~9 Ra)特征值之间,^(40)Ar/^(36)Ar=273~351,接近或略高于大气^(40)Ar/^(36)Ar特征值(295.5),不同矿床成矿流体中均有幔源组分的参与,地幔流体参与成矿作用是一个区域性事件。结合区内泥盆纪喷流沉积作用、燕山晚期花岗质岩体及构造特征等综合研究认为,参与成矿作用的地幔组分主要来自壳-幔相互作用过程中沿NW向深大断裂上升的深源地幔流体,丹池成矿带内成岩、成矿作用是燕山晚期同一构造-热事件产物,矿床成因属后生热液充填-交代成矿。The Danchi metallogenic belt in northwestern Guangxi is an important non-ferrous metal mining base in south China. He and Ar isotopes of fluid inclusions trapped in pyrite from the Ma’anshan Pb-Zn deposit and the Dashan Sn-Zn deposit of the Mangchang ore field, the Tongkeng Sn-polymetallic deposit of the Dachang ore field, and the Qianzhupo Pb-Zn polymetallic deposit of the Wuxu ore field have been studied in this paper. The results indicate that the 3 He/4 He values(0.79~5.32 Ra) of the ore-forming fluid are between those of crustal fluid(0.01~0.05 Ra) and mantle fluid(6~9 Ra);the^(40)Ar/^(36)Ar values(273~349) are close to or slightly higher than the atmospheric eigenvalue(295.5). He and Ar isotopes show that mantle fluid was involved in the mineralization in the area, and the ore-forming fluid was a mixture of mantle fluid, crust-sourced magmatic fluid and saturated atmospheric water. Based on the comprehensive study of Devonian exhalative deposition, granitic intrusion and tectonic characteristics, it is concluded that mantle fluid involved in mineralization is a regional event in the area. Mantle fluid is mainly derived from mantle components rising along NW deep faults during the crust-mantle interaction. The diagenesis and mineralization of Danchi metallogenic belt are the products of the same tectonic-thermal event in the Late Yanshanian period, and belong to the epigenetic hydrothermal filling-metasomatic mineralization.

关 键 词：HE-AR同位素 地幔流体 Sn多金属矿床 丹池成矿带 桂西北 

分 类 号：P611[天文地球—矿床学]