| 新疆维宝矽卡岩铜铅锌矿床维西矿段成矿流体性质和来源 |
| Received:November 17, 2016 Revised:February 20, 2017 点此下载全文 |
| 引用本文：ZHONG ShiHua,FENG ChengYou,REN YaQiong,LI DaXin,ZHAO YiMing.2017.Characteristics and sources of ore-forming fluid from Weixi ore block of Weibao skarn Cu-Pb-Zn deposit, Xinjiang[J].Mineral Deposits,36(2):483~500 |
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| Author Name | Affiliation | E-mail | | ZHONG ShiHua | MLR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China | | | FENG ChengYou | MLR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China | fengchy@cags.ac.cn | | REN YaQiong | MLR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China | | | LI DaXin | MLR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China | | | ZHAO YiMing | MLR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China | |
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| 基金项目:本文为国家重点研发计划（编号：2016YFC0600205）、国土资源部公益性行业科研专项经费项目（编号：201411025）、中国地质调查局地质调查项目（编号：1212011085528、12120113093600）、中国地质调查局高层次地质人才培养计划（编号：201309）和青年地质英才计划（编号：201112）资助的成果 |
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| 中文摘要:维宝矽卡岩铜铅锌矿床位于新疆与青海两省交界处，大地构造位置属祁漫塔格造山带西段，自西向东可以分为维西、主矿段和维东3个矿段。维西矿段以铜矿化为主，主矿段铜铅锌矿化均较发育，而维东矿段则以铅锌矿化为主。前人对维东矿段和主矿段进行了详细的流体地球化学研究，而对维西矿段尚未涉及。本次笔者选取维西矿段与铜矿化密切相关的矽卡岩和脉体，进行了流体包裹体和氢氧同位素研究。维西矿段主要发育3种类型的包裹体，即富液相包裹体、富气相包裹体和含CO2三相包裹体，前两种类型包裹体最为发育，激光拉曼分析显示它们的气体成分主要为H2O，含少量的CO2、CH4和N2，证明维西矿段成矿流体主要为H2O-NaCl体系；含CO2三相包裹体含量很少，仅出现于石英-硫化物阶段和石英-碳酸盐阶段，包裹体中气相成分为CO2。维西矿段成矿过程可以分为早期矽卡岩阶段、晚期矽卡岩阶段、石英-硫化物阶段和石英-碳酸盐阶段等4个阶段；随着流体演化，流体的温度和盐度均呈现出下降趋势，均一温度分别集中于440~490℃、410~453℃、300~410℃和150~220℃，而盐度w（NaCleq）则分别集中于14.0%~21.0%、13.4%~17.8%、8.0%~14.0%和2.0%~10.0%。石英-硫化物阶段可以进一步分为2个亚阶段：与铜矿化密切相关的脉体均一温度集中于380~410℃，而与铅锌矿化相关的脉体均一温度集中于300~380℃。氢、氧同位素分析表明维西矿段成矿流体最初来源于岩浆水，在石英-碳酸盐阶段与大气水发生大量混合，而石英-硫化物阶段的氢氧同位素变化则可能与岩浆脱气作用和富δ18O矿物的沉淀有关。大量的证据表明，温度下降和沸腾作用是引发维宝矿床矿质沉淀的诱因，而自西向东成矿流体温度的降低以及沸腾作用强度的减弱是造成维宝矿床空间上呈现矿化分带的主要因素。 |
| 中文关键词:地球化学 流体包裹体 氢氧同位素 矽卡岩矿床 维宝 新疆 祁漫塔格 |
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| Characteristics and sources of ore-forming fluid from Weixi ore block of Weibao skarn Cu-Pb-Zn deposit, Xinjiang |
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| Abstract:The Weibao skarn Cu-Pb-Zn deposit, located in the junction of Xinjiang and Qinghai and belonging to the west part of the Qimantag orogenic belt, is subdivided into the Weixi, the main and the Weidong ore blocks from west to east. The Weixi ore block is characterized by Cu mineralization, and the main and the Weidong ore blocks are mainly characterized by Cu-Pb-Zn and Pb-Zn mineralization respectively. Detailed fluid geochemical research on the main and the Weidong ore blocks was conducted by previous researchers; nevertheless, very insufficient survey has been conducted for the Weixi ore block of the Weibao deposit. In this study, skarns and ores closely related to Cu mineralization of the Weixi ore block were sampled and a detailed study with regard to fluid inclusions and H-O isotopes was conducted. The Weixi ore block develops three types of inclusions, i.e., liquid-rich (L-type), vapor-rich (V-type) and CO2-bearing three phases (C-type) fluid inclusions. L-type and V-type fluid inclusions are widespread and the analyses of the laser Raman revealed that the components of vapors in L-type and V-type fluid inclusions are dominantly H2O, with minor CO2, CH4 and N2; C-type fluid inclusions were only discovered in the quartz-sulfide and quartz-carbonate stages with vapors entirely composed of CO2. The ore-forming process in the Weixi ore block can be divided into four stages, i.e., the early skarn, the late skarn, the quartz-sulfide and the quartz-carbonate stages. During the evolution of the ore-forming fluid, both temperatures and salinities gradually decreased, with homogenization temperatures being 440~490℃, 410~453℃, 300~410℃ and 150~220℃ respectively and salinities w(NaCleq) being 14.0%~21.0%, 13.4%~17.8%, 8.0%~14.0% and 2.0%~10.0% respectively. The quartz-sulfide stages can be subdivided into two sub-stages: the former is related to Cu mineralization with homogenization temperatures of 380~410℃ and the latter is mainly related to Pb-Zn mineralization with homogenization temperatures of 300~380℃. Coupled H-O isotopes indicate that the ore-forming fluids of the Weixi ore blocks were derived from the magmatic water which was mixed with meteoric water in the quartz-carbonate stage, whereas the variations of H-O isotopes in the quartz-sulfide stage were most likely related to magmatic degassing and precipitation of δ18O-rich minerals. This study, combined with previously published data, indicates that cooling and boiling of the ore-forming fluid resulted in the precipitation of sulfides of the Weibao deposit, and the mineralization zoning from the west to the east was mostly likely controlled by the decreasing of the temperatures and boiling intensity of the ore-forming fluid. |
| keywords:geochemistry fluid inclusion H-O isotope skarn deposit Weibao Xinjiang Qimantag |
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