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茂租铅锌矿床地处扬子地块西缘,是川滇黔铅锌成矿域内赋存于震旦系灯影组白云岩中大型铅锌矿床的典型代表。其工业矿体呈似层状、脉状和不规则状。热液方解石和矿石硫化物(闪锌矿、方铅矿和黄铁矿)是主要矿物,其形成贯穿整个成矿过程。在矿床地质特征解析基础上,获得了热液方解石C-O同位素和矿石硫化物S-Pb同位素数据,结果表明热液方解石δ13 CPDB值和δ18 OSMOW值变化范围较窄,分别为-3.73‰～-1.95‰和+13.80‰～+14.95‰,在δ13 CPDB与δ18 OSMOW图上介于海相碳酸盐岩和原生碳酸岩范围间,呈弱负相关趋势,表明成矿流体中的CO2主要由海相碳酸盐岩溶解作用形成,并存在慢源和有机CO2加入;硫化物δ34SCDT值介于+13.35‰～+15.37‰,暗示成矿流体中的硫是海相硫酸盐岩热化学还原的产物,而含硫有机质热降解也有贡献;硫化物Pb同位素组成稳定,206Pb/204Pb,207Pb/204Pb和208Pb/204Pb值范围,分别为18.129～18.375,15.644～15.686和38.220～38.577,位于上地壳和造山带Pb演化线之间,落入基底岩石(昆阳群和会理群)Pb同位素组成范围内,表明成矿物质具有壳源特征,主要由基底岩石提供。综合各类地质-地球化学信息,认为茂租铅锌矿床成矿流体中不同组分来源不同,具有“多来源混合”特征,其成矿机制可以用“流体混合”模式来解释。
Maoxie lead-zinc deposit is located in the western margin of Yangtze block and is a typical representative of large-scale lead-zinc deposits hosted in the dolomite of the Sinian Dengying Formation in the lead-zinc mineralization area of Sichuan, Yunnan and Guizhou provinces. Its industrial orebodies are stratified, veins and irregular shape. Hydrothermal calcite and ore sulphides (sphalerite, galena and pyrite) are the main minerals that form throughout the mineralization process. Based on the analysis of the geological characteristics of the deposit, the S isotopic data of CO isotopes and sulfide ores of hydrothermal calcites were obtained. The results show that the δ13CFDB values and δ18SOSMOW values of hydrothermal calcites range from -3.73 ‰ to -1.95 ‰ and + 13.80 ‰ ~ + 14.95 ‰, showing a weak negative correlation trend between δ13CCPDB and δ18OSMOW in the range of marine carbonates and primary carbonates, indicating that the CO2 in ore-forming fluid is mainly composed of marine carbon The results show that δ34SCDT value of sulfide ranges from +13.35 ‰ to +15.37 ‰, suggesting that the sulfur in ore-forming fluid is the product of thermochemical reduction of marine sulfate rocks. However, The Pb isotopic composition of sulfide is also stable. The ranges of 206Pb / 204Pb, 207Pb / 204Pb and 208Pb / 204Pb range from 18.129 to 18.375, 15.644 to 15.686 and 38.220 to 38.577, respectively, which are located in the upper crust and orogenic belt Pb The evolutionary lines fall into the Pb isotopic composition of the basement rocks (Kunyang Group and Huili Group), indicating that the ore-forming materials have crustal features and are mainly provided by basement rocks. Based on various geo-geochemical information, it is concluded that the ore-forming fluids in the Mau-xi lead-zinc deposit have different origins and sources and have the characteristics of “multi-source mixing”, and their metallogenic mechanisms can be explained by the “fluid mixing” mode .