黔东南地虎-九星铜多金属矿床热液石英地球化学及其成因指示.pdf

分 类 号 P5 密级 公开 论文编号 2018021549 贵 州 大 学 2021 届硕士研究生学位论文 黔东南地虎-九星铜多金属矿床热液石英地球 化学及其成因指示 学科专业地质学 研究方向矿物学⋅岩石学⋅矿床学 导 师何明勤 教授 研 究 生张 丰 中国﹒﹒贵州﹒﹒贵阳 2021 年 06 月 万方数据 目录 摘 要 ................................................................................................................................................ I Abstract ........................................................................................................................................... III 第一章 前言 ..................................................................................................................................... 1 1.1 研究现状及存在问题 ........................................................................................................ 1 1.1.1 研究现状 ................................................................................................................. 1 1.1.2 存在问题 ................................................................................................................. 2 1.2 选题依据及研究意义 ........................................................................................................ 2 1.3 研究内容及分析测试方法 ................................................................................................ 3 1.3.1 研究内容 ................................................................................................................. 3 1.3.2 分析测试方法 ......................................................................................................... 4 1.4 完成工作量 ........................................................................................................................ 5 第二章 区域地质概况 ..................................................................................................................... 7 2.1 地层 .................................................................................................................................... 8 2.1.1 新元古界四堡群 ..................................................................................................... 8 2.1.2 新元古界下江群 ..................................................................................................... 8 2.1.3 第四系 ................................................................................................................... 10 2.2 构造 .................................................................................................................................. 10 2.2.1 褶皱 ....................................................................................................................... 11 2.2.2 断层 ....................................................................................................................... 11 2.3 岩浆岩 .............................................................................................................................. 12 2.3.1 基性-超基性岩 ..................................................................................................... 12 2.3.2 基性岩 ................................................................................................................... 12 2.3.3 花岗岩和花岗质混合岩 ....................................................................................... 13 2.4 变质岩 .............................................................................................................................. 14 2.5 矿产情况 .......................................................................................................................... 14 第三章 矿床地质特征 ................................................................................................................... 16 3.1 地虎铜多金属矿床 .......................................................................................................... 16 3.1.1 矿区地层 ............................................................................................................... 16 3.1.2 矿区构造 ............................................................................................................... 18 3.1.3 矿体特征 ............................................................................................................... 19 3.1.4 围岩蚀变 ............................................................................................................... 22 3.1.5 成矿阶段划分 ....................................................................................................... 23 3.2 九星铜多金属矿床 .......................................................................................................... 24 3.2.1 矿区地层 ............................................................................................................... 24 3.2.2 矿区构造 ............................................................................................................... 25 3.2.3 矿体特征 ............................................................................................................... 25 3.2.4 围岩蚀变 ............................................................................................................... 26 3.2.5 成矿阶段划分 ....................................................................................................... 29 第四章 流体包裹体地球化学 ....................................................................................................... 30 4.1 流体包裹体岩相学特征 .................................................................................................. 30 4.2 流体包裹体显微测温 ...................................................................................................... 35 4.2.1 流体包裹体均一温度 ........................................................................................... 35 万方数据 4.2.2 流体包裹体盐度 ................................................................................................... 38 4.2.3 流体包裹体密度 ................................................................................................... 41 4.2.4 成矿流体压力及深度 ........................................................................................... 42 4.3 流体包裹体激光拉曼成分分析 ...................................................................................... 43 4.4 成矿流体 H-O 同位素组成特征 ..................................................................................... 47 第五章 原位元素地球化学 ........................................................................................................... 49 第六章 石英地球化学研究对矿床成因的指示 ........................................................................... 56 6.1 成矿流体特征 .................................................................................................................. 56 6.2 成矿流体来源 .................................................................................................................. 57 6.3 成因指示 .......................................................................................................................... 57 结论 ................................................................................................................................................ 59 致谢 ................................................................................................................................................ 61 参考文献......................................................................................................................................... 62 附录 ................................................................................................................................................ 67 万方数据 I 黔东南地虎-九星铜多金属矿床热液石英地球化学及 其成因指示 摘摘 要要 地虎-九星铜多金属矿床位于贵州省黔东南从江地区，在大地构造上属于江 南造山带西南端，是从江地区 Cu-Au-Ag-Pb-Zn-Fe 多金属成矿区重要成矿代表。 本文在对地虎和九星铜多金属矿床野外地质观察和样品采集的基础上， 对样品进 行岩石学、矿相学观察，划定成矿阶段。并对石英流体包裹体进行显微测温，激 光拉曼、 H-O 同位素组成以及石英原位元素地球化学分析， 从流体包裹体及原位 元素地球化学方面进行研究，为明确矿床成因研究提供依据，取得以下认识 （1）根据矿体、矿石构造和矿物共生组合关系，将地虎和九星铜多金属矿 床的成矿过程都划分为四个成矿阶段石英-磁铁矿黄铁矿阶段（S1 阶段） 、石 英-铜硫化物阶段（S2 阶段） 、石英-多金属硫化物阶段（S3 阶段）和石英-少量 磁铁矿或黄铁矿阶段（S4 阶段） 。 （2）岩相学特征显示流体包裹体有纯液体包裹体 （Ⅰ型） 、富液体包裹体（Ⅱa 型） 、富气体包裹体（Ⅱb 型）和纯气体包裹体（Ⅲ型）四种类型，其中富液体包 裹体（Ⅱa 型）在两个矿床中都最为发育，在各阶段可达总数的 50以上。 测温结果显示， 地虎铜多金属矿床流体 S1-S4阶段平均温度从 244℃、 229℃、 209℃到 208℃有降低的趋势，整个阶段温度为 126℃370℃，平均 225℃；九星 铜多金属矿床流体 S1-S4 阶段平均温度从 218℃、230℃、209℃到 208℃有先升 高后降低的趋势，整个阶段温度为 113℃380℃，平均 217℃。两个矿床的大多 数流体包裹体落在 160℃260℃温度区间内，显示中低温的成矿特征，且地虎铜 多金属矿床成矿温度（225℃）略高于九星铜多金属矿床（217℃） 。 地虎铜多金属矿床流体 S1-S4 阶段平均盐度分别为 9.57NaCleqv、 9.61NaCleqv、 9.48NaCleqv和8.02NaCleqv， 整 个 阶 段 盐 度 为 3.7120.67NaCleqv， 平均 9.23NaCleqv； 九星铜多金属矿床流体 S1-S4 阶段平 均盐度分别为 10.35NaCleqv、9.33NaCleqv、9.98NaCleqv和 8.45NaCleqv，整 个阶段盐度为 2.9019.45NaCleqv，平均 9.55NaCleqv。两个矿床流体均为中 万方数据 II 低盐度流体，且九星铜多金属矿床的盐度略高，并且都在 S4 阶段盐度降低（均 值降到 9NaCleqv以下） 。 地虎铜多金属矿床流体密度平均为 0.905g/cm3，压力平均为 222bar，成矿深 度平均为 837m；九星铜多金属矿床流体密度平均为 0.913g/cm3，压力平均为 217bar， 成矿深度平均为 821m， 显示两个矿床均属于中等密度流体的浅成矿床。 （3）激光拉曼分析结果显示，地虎铜多金属矿床各阶段流体包裹体成分均 含有 H2O、CO2和 N2，在 S1-S3 阶段出现 CH4；九星铜多金属矿床各阶段流体包 裹体成分均含有 H2O、 CO2和 N2， CH4仅在 S1 阶段发现， 且信号强度极其微弱。 因此，地虎和九星铜多金属矿床成矿流体体系均为 NaClH2OCO2N2CH4体 系，并且流体可能是从地虎矿区向九星矿区发生迁移演化。 （4）H-O 同位素分析结果显示，两个矿床成矿流体中的水均主要来自于变 质水。在 H-O 同位素判别图解中，地虎铜多金属矿床 S3-S4 阶段和九星铜多金 属矿床 S4 阶段的水稍微偏离了变质水范围，可能是变质热液与围岩发生了水岩 反应，使流体的 δ18O 值略微降低，且地虎铜多金属矿床的水岩反应可能比九星 铜多金属矿床相对更强烈。 （5）原位元素地球化学分析结果显示，地虎和九星铜多金属矿床石英 Ti 含 量 均 小 于 10ppm ， 表 示 形 成 温 度 小 于 350℃ 。 Al 含 量 变 化 范 围 小 （1.9ppm24.9ppm） ，表示成矿过程中流体的 pH 值较为稳定，且地虎铜多金属 矿床石英 Al 含量无论是各阶段还是整个 S1-S4 阶段，都略低于九星铜多金属矿 床，说明九星铜多金属矿床 pH 略高。据脉体形成温度和 Al 含量变化，表示地 虎-九星铜多金属矿床有和浅成低温热液矿床相似的地球化学特征。 （6）综上所述，地虎和九星铜多金属矿床的成矿流体具有中低温 （160℃260℃） ， 中低盐度 （均值＜10NaCleqv） 的特点， 成矿深度浅 （＜1000m） ， 且流体中的水主要来自变质水，矿床成因类型为浅成中低温变质热液矿床。 关键词关键词 流体包裹体； 石英地球化学； 成因指示； 地虎-九星铜多金属矿床； 黔东南 万方数据 III Geochemistry of hydrothermal quartz and its genetic indications of the Dihu-Jiuxing copper polymetallic deposits in southeast Guizhou province Abstract The Dihu-Jiuxing copper polymetallic deposits of Congjiang country, southeast Guizhou province, are located in the southwest Jiangnan orogenic belt, which are important ore-ing represents of Congjiang Cu-Au-Ag-Pb-Zn-Fe polymetallic ore- ing area. On the basis of field geological survey and sample collection, we carry out petrology and mineralography observation of the samples to classify the ore- ing stages. And then carry out microscopic temperature measurement of quartz fluid inclusions, analysis of the Laser Raman spectroscopy, H-O isotopic and quartz in- situ geochemistry. The research of fluid inclusions and in-situ element geochemistry provides a basis of ore deposit genesis, and the results are as follows 1 According to orebody, ore structure and mineral intergrowth association, the ore-ing process of both Dihu and Jiuxing copper polymetallic deposits can be divided into four ore-ing stages quartz magnetite and pyrite stage S1 stage, quartz copper sulfide stage S2 stage, quartz polymetallic sulfide stage S3 stage, quartz a few magnetite or pyrite stage S4 stage. 2 Petrographic characteristics show that fluid inclusions can be classified into four types pure liquid inclusions Ⅰ type, liquid rich inclusions Ⅱa type, gas rich inclusions Ⅱb type and pure gas inclusions Ⅲ type. The liquid rich inclusions Gd A type are the most developed in the two deposits and can account for more than 50 of the total in each stage. The temperature measurement results show that the average temperature of fluid inclusions from S1 to S4 stage of the Dihu copper polymetallic deposit decreases from 244℃, 229℃, 209℃ to 208℃, and the temperature of the whole stages is 126℃ 370℃, with an average of 225℃. The average temperature of fluid inclusions from S1 to S4 stage of the Jiuxing copper polymetallic deposit increases firstly and then 万方数据 IV decreases from 218℃, 230℃, 209℃ to 208℃, and the temperature of the whole stages is 113℃ 380℃, with an average of 217℃. Most of the fluid inclusions in the two deposits also fall in the temperature range of 160℃260℃, showing the ore-ing characteristics of medium-low temperature, and the ore-ing temperature of the Dihu copper polymetallic deposit 225℃ is slightly higher than that of the Jiuxing copper polymetallic deposit 217℃. The average salinity of fluid inclusions from S1 to S4 stage of the Dihu copper polymetallic deposit is 9.57NaCleqv, 9.61NaCleqv, 9.48NaCleqv and 8.02NaCleqv, respectively, and the salinity of the whole stages is 3.71 20.67NaCleqv, with an average of 9.23NaCleqv. The average salinity of fluid inclusions from S1 to S4 stage of the Jiuxing copper polymetallic deposit is 10.35NaCleqv, 9.33NaCleqv, 9.98NaCleqv and 8.45NaCleqv, respectively, and the salinity of the whole stages is 2.90 19.45NaCleqv, with an average of 9.55NaCleqv. Fluid inclusions of the two deposits are medium-low salinity, and the salinity of the Jiuxing copper polymetallic deposit is slightly higher. Meanwhile, the salinity of both deposits decreases in the S4 stage average value＜9NaCleqv. The average fluid density of the Dihu copper polymetallic deposit is 0.905g/cm3, the average pressure is 222bar, and the average ore-ing depth is 837m. The average fluid density of the Jiuxing copper polymetallic deposit is 0.913g/cm3, the average pressure is 217bar, and the average mineralization depth is 821m. It shows that the two deposits belong to shallow deposits with medium density fluid. 3The results of Laser Raman component analysis show that the fluid inclusions in the S1-S4 stage of the Dihu copper polymetallic deposit all contain H2O, CO2 and N2. And CH4 appears in the S1-S3 stage. The fluid inclusions in the S1-S4 stage of the Jiuxing copper polymetallic deposit all contain H2O, CO2 and N2. And CH4 is only found in the S1 stage, but the signal strength is extremely weak. Therefore, the ore- ing fluids system of both Dihu and Jiuxing copper polymetallic deposits is NaClH2OCO2N2CH4, and the fluid may have migrated and evolved from Dihu to Jiuxing mining area. 万方数据 V 4 The results of H-O isotopic analysis show that the water in the hydrothermal fluids of the two deposits mainly derive from the metamorphic water. In the H-O isotope discriminant diagram, the water in S3-S4 stage of the Dihu copper polymetallic deposit and S4 stage of the Jiuxing copper polymetallic deposit is slightly out of the metamorphic water range. It may be the metamorphic hydrothermal fluids react with the surrounding rock, which makes the δ18O value in the fluids slightly lower, and the water-rock reaction of the Dihu copper polymetallic deposit may be stronger than that of the Jiuxing copper polymetallic deposit. 5 The results of in-situ geochemical analysis show that the content of Ti in quartz is less than 10ppm, indicating that the ation temperature is less than 350℃. The content of Al varies in a small range 1.9ppm 24.9ppm, indicating that the pH value of the fluids is relatively stable during the ore-ing process, and the content of Al in the Dihu copper polymetallic deposit is slightly lower than that of the Jiuxing copper polymetallic deposit in each stage or the whole stages, indicating that the pH value of the Jiuxing copper po