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Sediment-hosted lead-zinc deposits in northwestern Guizhou, China, are located on the southwest margin of the Yangtze craton and Youjiang orogenic belt. They are hosted by Proterozoic and Paleozoic carbonate rocks along the Ziyun-Yadu Fault. The ore minerals include sphalerite, galena, and pyrite, with minor tetrahedrite.This study focus on mineralogy and geochemistry of ores, petrography, microthermometry, laser Raman spectroscopy and LA-ICP-MS analyses of fluid inclusions, and sulfur, lead, zinc isotopic compositions of sulfides are used to characterize the ore-forming fluids associated with Pb-Zn mineralization in the northwestern Guizhou, and to understand the formation of lead-zinc deposits in northwestern Guizhou, China. The results and conclusions are followings:1. The ore consists mainly of sphalerite, galena, and pyrite, with quartz, calcite and dolomite veins. The sphalerite and galena have high concentrations of Ag (68 to138ppm), As (3 to 1570 ppm), Sb (2 to 3840 ppm) and Se (20 to 1020 ppm) determined by eletron microprobe analysis (EPMA). Minor tetrahedrite containing As (3 to 20 wt%), Sb (6 to 20wt%), and Au (500 to 1000ppm) is the first indentified in some deposits and intergrows with sphalerite and galena or cutting sphalerite.2. Fluid inclusion studies show that the fluid inclusions in quartz are two-phase, aqueous inclusion and have higher homogenization temperatures (160～260℃) and salinities of 5～22 wt%NaCl equiv., with low density of CO2, CH4 and N2 vapor determined by Laser spectroscopy, whereas the homogenization temperatures of two-phase aqueous inclusions in sphalerite range from 160～180℃, with salinities of 3～23 wt%NaCl equiv. LA-ICP-MS microanalysis indicate that fluid inclusions in quartz contain high contents of Cl (14～38 wt %)、K (2184～78451 ppm), Cu (2～387 ppm), Pb (2～14043 ppm), Zn (12～4350ppm), As (4～1186 ppm), and Sb (1～99 ppm). The correlation of Cu, Pb, Zn and Cl suggests that these metals are transported by chlorine complexes. Hydrogen and oxygen isotopes (δ18OH2O=1.8‰～17.0‰，δD=-46‰～-55‰) suggest derivation from metamorphic water.3. Sulfur isotopic compositions of sulfides indicate that reduced sulfur was mainly derived from the host rocks. Lead isotopic compositions of sulfides (206Pb/204=17.999~18.569, Pb207Pb/204Pb=15.673~15.764, and 208Pb/204Pb=38.083～39.126) indicate the metals were derived from the upper crust, possibly basement sedimentary rocks. 4. Zinc isotopic compositions of sphalerite vary each deposit in the region. The brown sphalerites hosted in Proterozoic and Cambrian carbonate have light zinc isotopes (δ66ZnIRMM=-0.406‰～-0.647‰, δ68ZnIRMM=-0.852‰～-1.284‰), whereas the yellow sphalerites hosted in Devonian to Permian carbonate enriched heavy zinc isotopes (δ66ZnIRMM=-0.347‰～-0.242‰, δ68ZnIRMM=-0.500‰～-0.684‰). Variation of zinc isotopes is controlled by trace elements such as Fe and Cu in sphalerite, and temperature of ore fluids.5. We proposed a model in which the metamorphic ore fluids were generated by metamorphism of deep sedimentary rocks during the Yanshanian orogeny along the Ziyun-Yadu fault and flowed along thrust faults in the basement, upward into structures in response to stress relaxation during the orogeny. Sulfides such as sphalerite and galena precipitated where the ore fluids mixed with reduced sulfur from the host rocks. 

黔西北铅锌成矿区是川－滇－黔铅锌矿集区和西南大面积低温成矿域的重要组成部分，是我国重要的铅、锌、银、锗的重要产地之一。区内产有众多的铅锌矿床，这些铅锌矿床主要产于水城－紫云－南丹深大断裂带之中或其附近，矿体受层间滑脱断裂或低角度断裂控制，具有多层位控矿的特点，赋矿层位从震旦系一直到二叠系，其容矿岩性主要为碳酸盐岩。本文在前人研究成果和野外地质调查基础上，重点选择洗米沟、沙坡脚（绿卯坪）、纳雍枝等铅锌矿床为主要研究对象，采用电子探针、流体包裹体岩相学与显微测温学、流体包裹气相成分的激光Raman以及同位素地球化学等分析技术，对该区部分铅锌矿床矿石显微岩相学结构、矿物学与地球化学、成矿物质与成矿流体来源以及成矿过程等进行了较系统研究，取得以下认识：（1）矿物学与地球化学研究表明，黔西北地区不同赋矿层位的铅锌矿床金属矿物主要为闪锌矿、方铅矿和黄铁矿等硫化物，脉石矿物主要有石英、方解石和白云石等。电子探针成分分析表明，闪锌矿和方铅矿中含有较高的Ag(68～138ppm)、As(3～1570ppm)、Sb(2.3～3840ppm)、Se(20～1020ppm)、Cd(5.5～2870ppm)等微量元素。同时在部分铅锌矿床矿石中新发现了砷黝铜矿和锑黝铜矿两种矿物，并含有Au 500～1000ppm、As 3～20wt%、Sb 6～20wt%。（2）确定了黔西北地区不同赋矿层位铅锌矿床成矿流体的性质与化学组成。石英和闪锌矿中流体包裹体研究表明，成矿流体具有中低温（160～280℃）、较高盐度（5～22 wt%NaCl）、含有低密度（0.85～1.10g/cm3)的CO2、CH4和N2的卤水特征，不同于MVT型铅锌矿床成矿流体特征。单个流体包裹体成分的LA-ICP-MS分析表明，该类矿床石英流体包裹体中含有较高Na、K（2184～78451ppm）、Cu（2～387ppm）、Pb（2～14043ppm）、Zn（12～4350ppm）、As（4～1186ppm）、Sb（1～99ppm）等元素，其中Cu、Pb、Zn、Cl元素之间具有正相关关系，认为Pb、Zn、Cu等成矿元素的Cl络合物是成矿元素的主要搬运形式。前人的氢氧同位素组成分析结果（δ18OH2O=1.8‰～17.0‰，δD=-46‰～-55‰）显示，成矿流体可能主要为变质流体成因。（3）硫化物硫同位素地球化学研究表明，不同赋矿层位铅锌矿床具有不同的硫同位素组成，与相应地层时代蒸发岩硫酸盐和生物成因硫化物硫同位素组成相似，认为铅锌成矿所需的硫源可能主要来自赋矿地层本身。（4）铅同位素地球化学研究显示，硫化物的206Pb/204Pb、207Pb/204Pb和208Pb/204Pb变化范围分别为17.937～18.746、15.660～15.804和38.032～39.447，在铅同位素组成图解中均位于上地壳铅演化线上方或其附近，暗示这些硫化物中的铅主要来源于地壳。（5）闪锌矿Zn同位素地球化学研究表明，区域上不同赋矿层位铅锌矿床中闪锌矿的颜色与δ66Zn和δ68Zn值存在明显差异，早期形成的深棕色闪锌矿富集Zn的轻同位素（δ66Zn=-0.406‰～-0.647‰、δ68Zn=-0.852‰～-1.284‰），而晚期形成的浅黄色闪锌矿则富集Zn的重同位素（δ66Zn=-0.347‰～-0.242‰、δ68Zn=-0.500‰～-0.684‰）。成矿流体的温度变化是导致Zn同位素分异的主要因素，闪锌矿中的Fe、Cu等微量元素含量变化则控制闪锌矿的颜色。（6）硫化物Sr同位素研究显示，除半坡矿床外，大多数矿床闪锌矿样品的Sr同位素组成比较均一，87Sr/86Sr变化范围为0.709～0.712，均高于同时代赋矿围岩的海相碳酸盐岩，推测成矿流体可能来自或流经富放射成因Sr的碎屑岩基底地层。（7）结合地球化学热力学分析，认为Pb、Zn等成矿元素的Cl络合物是成矿元素的主要搬运形式，富含Pb、Zn的成矿流体与赋矿地层中富含H2S还原性流体的混合是铅锌富集成矿的重要机制之一。（8）运用最新地球物理资料，通过对紫云-垭都断裂带构造演化历史的分析，建立了黔西北地区铅锌矿成矿的“构造－流体混合”模式，并提出了可以利用闪锌矿颜色变化来寻找深部矿体的矿物学标志。