(1. 昆明理工大学 国土资源工程学院，昆明 650093；
2. 有色金属矿产地质调查中心西南地质调查所，昆明 650093；
3. 昆明理工大学 城市学院，昆明 650093)
摘 要: 金牛厂铅锌矿床是川滇黔铅锌多金属成矿区滇东北矿集区内产于下寒武统筇竹寺组泥质、钙质粉砂岩中的铅锌矿床，属于非碳酸盐岩容矿的后生热液矿床。区内赋矿地层筇竹寺组Pb、Zn含量异常高，而矿石Pb同位素组成与基底岩石(昆阳群)基本一致，矿源层是基底还是筇竹寺组、该矿床与区内其他赋存于碳酸盐岩中的铅锌矿床成矿机理是否具有一致性，直接关系到铅锌成矿系统研究与矿床深部找矿预测。基于流体包裹体测温及硫化物H-O-S-Pb同位素组成分析，结果表明：1) 流体包裹体均一温度为165~274 ℃，平均216 ℃；盐度为6.5%~14.0%NaCleqv，平均值为7.8%NaCleqv，指示成矿流体属于中低温-中低盐度的富气相流体；显微激光拉曼光谱分析显示流体包裹体的液相成分主要为H2O，气相成分主要为CH4；2) 脉石矿物石英的H、O同位素特征表明，成矿流体主要来源于流经深部褶皱基底(昆阳群)的深部流体和含有机质的盆地卤水的混合；3) 硫化物δ34 S值与川滇黔成矿区内主要铅锌矿床具有相似性，其还原S主要来源于下伏地层震旦系灯影组和下寒武统渔户村组白云岩中硫酸盐的热化学还原硫作用(TSR)过程；4) 硫化物的Pb同位素组成不仅与基底岩石的铅同位素比值一致，且沿上地壳Pb平均演化线呈直线分布，表明壳源Pb源主要来自基底岩石(昆阳群)，赋矿围岩下寒武统筇竹寺组碎屑岩也贡献了部分Pb。结合矿床对比研究，认为该矿床和川滇黔成矿区内主要铅锌矿床是在同一成矿地质背景下形成，具有相似的成矿模式，但在赋矿围岩、赋矿断裂性质、矿质来源等方面存在自身的特点。该研究可为川滇黔成矿区内铅锌成矿系统研究提供依据，也为该区矿床深部及外围找矿提供新思路。
关键字: 流体包裹体测温；H-O-S-Pb同位素；成矿物质来源；成矿模式；金牛厂铅锌矿床
（1. Kunming University of Science and Technology, Faculty of Land Resources Engineering, Kunming 650093, China;
2. SouthwestInstitute of Geological Survey, Geological Survey Center for Non-ferrous Metals Resources, Kunming 650093, China;
3. City College, Kunming University of Science and Technology, Kunming 650093, China）
Abstract:The Jinniuchang Pb-Zn deposit hosted in the argillaceous and calcareous siltstone of the Lower Cambrian Qiongzhusi Formation is a non-carbonate-hosted epigenetic hydrothermal deposit in the deposit-concentrated district in northeastern Yunnan of the Sichuan–Yunnan–Guizhou Pb-Zn polymetallic metallogenic triangle area(SYGT). The content of Pb and Zn in the ore-bearing strata of the mining area is abnormally high, and the Pb isotopic composition of the ore is basically consistent with that of the basement rocks (Kunyang group). Whether the ore source layer is the basement or the Qiongzhusi Formation, and whether the Jinniuchang deposit has the same metallogenic mechanism as other carbonate-hosted Pb-Zn deposits in the district, which are related to the Pb-Zn metallogenic system and the prospecting potential of deep deposits. Based on the microthermometry of fluid inclusions and the sulfide H-O-S-Pb isotopic composition analysis, the following results are achieved: 1) The homogenisation temperatures of fluid inclusions in quartz range from 165 ℃ to 274 ℃, with an average value of 216 ℃; the salinity range from 6.5% to 14.0% NaCleqv, with an average value of 7.8% NaCleqv, indicating the ore-forming fluid belongs to the gas-rich fluid with medium-low temperature and medium-low salinity. Microscopic laser Raman spectroscopy analysis shows that the liquid phase composition of fluid inclusions is mainly H2O, and the gas phase composition is mainly CH4. 2) The H and O isotopic composition characteristics of the gangue mineral quartz indicate that the ore-forming fluid is mainly derived from the mixing of deep source metamorphic water flowing through deep fold basement (Kunyang group) and organic-containing basin brine. 3) The sulfides'''' δ34S values are similar to the main Pb-Zn deposits in the SYGT, which is interpreted as that the reduced S is mainly derived from sulfates in marine sedimentary rocks in dolomites of the Sinian Dengying Formation and the Lower Cambrian Yuhucun Formation through thermochemical reduction of sulfur (TSR). 4) Sulfides have Pb isotopic compositions that form a linear trend on the average crustal Pb growth curve in 207Pb/204Pb vs. 206Pb/204Pb plot. Moreover, Pb isotopic ratios are consistent with the basement rocks, consequently suggesting crustal Pb sources with the majority of Pb are derived from the basement rocks (Kunyang group). The clastic rocks of the Lower Cambrian Qiongzhusi Formation also provide part of the Pb sources. Combined with the comparative study of the deposit, we conclude that the Jinniuchang deposit and major Pb-Zn deposits in the SYGT formed under the same metallogenic geological background and had a similar metallogenic model, but the Jinniuchang deposit has its own characteristics in terms of ore-bearing wall rock, ore-bearing fracture properties, and mineral sources. This achievement provides a basis for the study of the Pb-Zn metallogenic system and a new idea for the deep and peripheral prospecting of the Pb-Zn deposits in the SYGT.
Key words: microthermometry of fluid inclusions; H-O-S-Pb isotopes; source of ore-forming materials; metallogenic model; Jinniuchang Pb-Zn deposit
