黔东松桃嗅脑铅锌矿床成矿物质来源:稀土元素与碳、氧、硫、铅同位素制约  

Sources of metallogenic materials of Xiunao Pb-Zn deposit in eastern Guizhou: constraints from REE and C,O,S,Pb isotope geochemistry

作　　者：李堃[1,2] 汤朝阳[2] 刘劲松[2] 蔡应雄[2] 刘飞[2] LI Kun;TANG Zhao-yang;LIU Jin-song;CAI Ying-xiong;LIU Fei(Faculty of Earth Resources,China University of Geosciences,Wuhan 430074,China;Wuhan Center of Geological Survey,China Geological Survey,Wuhan 430205,China)

机构地区：[1]中国地质大学(武汉)资源学院,武汉430074 [2]中国地质调查局武汉地质调查中心,武汉430205

出　　处：《桂林理工大学学报》2018年第3期365-376,共12页Journal of Guilin University of Technology

基　　金：中国地质调查局项目(1212011121100; DD20160034)

摘　　要：贵州松桃县嗅脑铅锌矿床与湖南花垣超大型铅锌矿床毗邻,是黔东地区具有代表性的铅锌矿床之一。在研究该矿床稀土元素与碳、氧、硫、铅同位素特征的基础上,探讨了成矿流体与成矿物质来源。嗅脑铅锌矿床矿石的稀土元素组成具有总稀土(ΣREE范围为2.03×10^(-6)～3.01×10^(-6))含量低、轻稀土富集、较高的LREE/HREE值、Eu和Ce均呈不同程度负异常等特点,与碳酸盐围岩的稀土配分模式较为一致,表明成矿物质有一部分可能来源于围岩。成矿期方解石的δ^(13)C_(PDB)值(-1.23‰～0.42‰)和δ^(18)O_(SMOW)值(15.35‰～19.51‰)均略低于碳酸盐围岩的δ^(13)C_(PDB)值(-0.79‰～2.39‰)和δ^(18)O_(SMOW)值(18.81‰～21.50‰),表明成矿流体与围岩发生水-岩反应导致了成矿期方解石的沉淀,成矿流体中的碳来源于碳酸盐围岩。硫化物δ^(34)S值变化范围为26.3‰～34.9‰,以富含重硫为主,表明硫来源于碳酸盐地层中硫酸盐的热化学还原作用(TSR)。硫化物铅同位素变化范围较小且组成均一,^(206)Pb/^(204)Pb、^(207)Pb/^(204)Pb、^(208)Pb/^(204)Pb值分别为17.952～18.262、15.641～15.811、38.015～38.663,表明铅主要来源于上地壳,并且具有高铅锌含量的下伏地层为成矿提供了大量金属物质。The Xiunao Pb-Zn deposit located along the southeastern margin of the Yangtze Craton is a representative deposit in Guizhou-Hunan metallogenic belt in south China.The REE and C,O,S,Pb isotopes geochemistry were analyzed,in order to understand the sources of ore-forming fluids and metallogenic materials.The ores have low contents ofΣREE(range from 2.03×10-6 to 3.01×10-6),light REE enrichment,high LREE/HREE value,negative Eu and Ce anomaly.On the chondrite-normalized REE patterns,the characteristic of ores are accord with the patterns of wall rock,indicating that part of the metal sources may come from wall rock.Theδ13 C PDB values(range from-1.23‰to 0.42‰)andδ18 O SMOW values(range from 15.35‰to 19.51‰)of hydrothermal calcites are lower than theδ13 C PDB values(range from-0.79‰to 2.39‰)andδ18 O SMOW values(range from 18.81‰to 26.50‰)of carbonate wall rock.Precipiation of hydrothermal calcites were likely due to extensive fluid-rock interaction between ore-forming fluids and carbonate wall rock.The C of the ore-forming fluids is mainly sourced from carbonate wall rock.The sulfides have narrow range ofδ34 S values(from 26.3‰to 34.9‰),suggesting that the sulfur should be derived from the carbonate sedimentary strata by thermochemical sulfate reduction,as the organic matter played an important role.The 206 Pb/204 Pb,206 Pb/204 Pb and 206 Pb/204 Pb values of minerals range from 17.952 to 18.262,from 15.635 to 15.811,from 38.015 to 38.663,showing that the Pb isotope ratios are relatively homogeneous and similar to upper crust.The underlying strata with high Pb-Zn contents may offer a lot of metal materials for mineralization.

关 键 词：稀土元素 碳、氧、硫、铅同位素 成矿物质来源 嗅脑铅锌矿床 黔东 

分 类 号：P618.4[天文地球—矿床学]