| 西藏尤卡朗铅银矿床成矿作用初步研究 |
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| 引用本文：冯志兴,吕新彪,王涛.2011.A preliminary study of metallogenesis of Youqialang lead-silver deposit, Tibet[J].Mineral Deposits,30(3):469~476 |
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| 基金项目:本文得到西部矿业公司“西藏尤卡朗铅银矿综合找矿研究项目”资助 |
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| 中文摘要:西藏尤卡朗铅银矿床产于中侏罗统拉贡塘组受岩浆热变质的砂泥质岩中，与矿区北部出露的燕山期至喜马拉雅期中酸性侵入岩体有关。矿体的产出和分布受到北北东向断裂构造的控制，尤其是多期活动的节理造成局部矿化富集。成矿作用可划分为5个阶段，包括石英菱铁矿阶段、铅锌（银）矿化阶段、细粒铅银矿化阶段、黄铁矿化阶段和石英脉阶段。矿石中硫化物δ34S值为-3.62‰～-9.47‰。闪锌矿和方铅矿平衡硫同位素温度值为214℃。单矿物的铅同位素206Pb/204Pb分布于18.683～18.923之间，207Pb/204Pb分布于15.684～15.800之间，208Pb/204Pb为39.090～39.581，μ值在9.60和9.82之间，Th/U比值在3.88和4.05之间，在构造环境图解中位于上地壳附近，可能与俯冲带中海底沉积物随洋壳板片俯冲进入地幔的重熔岩浆作用有关。流体包裹体研究表明，成矿温度为中温，流体盐度不高且有降低的趋势，成矿热液主要来源于岩浆期后热液，推测地下水混入成矿热液导致铅银矿的形成。 |
| 中文关键词:地质学 成矿作用 流体包裹体 稳定同位素 铅银矿 尤卡朗 西藏 |
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| A preliminary study of metallogenesis of Youqialang lead-silver deposit, Tibet |
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| Abstract:The Youqialang lead-silver deposit is hosted in thermal metamorphosed arenaceous or argillaceous rocks in Middle Jurassic Lagongtang Formation, related to the Yanshanian-Himalayan intermediate-acidic intrusive bodies outcropped in the north of the orefield. Modes of occurrence and distribution of ore bodies are controlled by NNE-trending faulted structures, especially by multiperiodic active metallogenic joints, which resulted in local mineralization concentration. The ore-forming processes of the lead-silver deposit can be divided into five stages, i.e., quartz-siderate stage, lead-zinc (silver) mineralizing stage, finely granular lead-silver mineralizing stage, pyrite stage, and quartz vein stage. δ34S values (-3.62‰～-9.47 ‰) of ore sulfide minerals are slightly lower than those of meteorolite, with the equilibrium temperature of sphalerite-galena being 214℃. Lead isotope ratios of single minerals are 206Pb/204Pb 18.683～18.923, 207Pb/204Pb 15.684～15.800, 208Pb/204Pb 39.090～39.581, and μ values 9.60～9.82, with Th/U ratios being 3.88～4.05. These values are close to the values of the upper-crust area in the structural environment scheme, probably related to remelting magmatism of submarine sediments in the subduction zone with the subduction of the oceanic crust into the mantle. Research on fluid inclusions indicates that the mineralizing temperatures were intermediate, salinities of fluids showed declining trend, the mineralizing hydrothermal fluids were derived mainly from post-magmatic fluids with the mixture of groundwater, and their actions resulted in lead-silver mioeralization. |
| keywords:geology, metallogenesis, fluid inclusion, stable isotope, lead-silver deposit, Youqialang, Tibet |
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