【作者】 张辉；

【导师】 徐九华；

【作者基本信息】 北京科技大学 ， 采矿工程， 2017， 博士

【摘要】 阿尔泰地区早中泥盆世形成的VMS矿床在晚泥盆世以来的造山环境里经受了强烈的变形变质作用,目前对于该地区VMS矿床变形变质以及后期叠加成矿作用的研究还比较薄弱。因此本论文就这一方面做了重点研究,提出了成矿作用的新认识。本文在野外地质调查基础上,对阿尔泰克兰盆地内塔拉特铅锌矿床、铁木尔特铅锌矿床开展了详细的矿床地质、成矿流体以及矿床地球化学研究,获得了一系列最新成果,总结出该地区同类型矿床的成矿模式,并对该区找矿潜力做出评价。塔拉特铅锌矿床与铁木尔特铅锌矿床是克兰盆地内典型的海相火山沉积矿床,赋存于下泥盆统康布铁堡组变质岩系,具有明显的层控特征,后期脉状硫化物-石英脉叠加作用明显,可以识别出2个明显的成矿期：海相火山喷流沉积成矿期和变质热液叠加成矿期。这两个矿床在晚石炭世以来的阿尔泰造山运动中均遭受了强烈的变形变质作用,条带状、层纹状硫化物矿石与围岩一起在不同程度上被改造。塔拉特铅锌矿床富CO₂流体包裹体发育,早期变质石英脉Q1和晚期石英脉Q2中原生CO₂-H₂O包裹体均一温度分别为294～368℃、142～360℃,最小捕获压力为100～370 MPa。铁木尔特铅锌矿床与金矿化有关的热液流体主要由富CO₂流体组成,Th,tot为180～³⁴2℃,最小捕获压力为100～350 MPa,金矿化来源于变质流体体系。富CO₂流体的形成环境与造山带区域变质晚期或峰期后的P-T演化一致。铁木尔特铅锌矿及萨热阔布金矿的黄铜矿铜同位素组成分别为δ⁶⁵Cu=-0.14‰～-0.02‰ （3）、δ⁶⁵Cu=-0.28‰～0.12‰ （2）,该金矿化的成因类型与萨热阔布金矿同为造山型。克兰盆地内典型海相火山沉积矿床闪锌矿锌同位素组成为:δ66Zn=0.00～0.09‰（3）,其成因类型为VMS矿床。闪锌矿Rb-Sr同位素测试显示出克兰盆地海相火山沉积铅锌矿床的成矿时代为早泥盆世（392±92Ma）。而萨热阔布金矿的黄铁矿、黄铜矿Rb-Sr同位素测试反映出晚二叠世—三叠纪发生的造山-变质成矿作用（237±53Ma）。硫同位素和铅同位素分析显示,硫(δ³⁴S=-26.46‰～+4‰)主要来源于的海水硫酸盐的无机还原和细菌还原作用。矿石硫化物铅同位素较为均一(²⁰⁶Pb/²⁰⁴Pb=16.86～18.073,²⁰⁷Pb/²⁰⁴Pb=15.42～15.623,²⁰⁸Pb/²⁰⁴Pb =37.27～38.097),铅可能来自于地幔物质与围岩的均匀混合作用。本次工作建立了该地区同类型矿床的成矿模式,早泥盆世额尔齐斯古亚洲洋洋壳向西伯利亚板块的俯冲作用导致阿尔泰南缘形成弧后拉张盆地,由海底喷流沉积成矿作用形成了一系列海相火山沉积铅锌矿床。而在晚石炭世一早三叠世,阿尔泰地区发生强烈的弧陆碰撞造山运动,诱发了大规模的变形变质作用,富CO₂的变质流体不断萃取具有Au高背景值地区的火山岩地层中的Au,并在构造有利部位发生沉淀,形成萨热阔布金矿和铁木尔特上部金矿化。通过对该地区已有地质勘查资料的分析研究,认为铅锌矿体深部具有较大的延伸,具有一定的成矿潜力。此外在变形变质强烈的区域,特别是脉状硫化物发育地段具有形成金（铜）矿床化的潜力。更多还原

【Abstract】 The VMS deposits in Kelan volcanic-sedimentary basin of Southern Altay, formed in the Early-Middle Devonian, was subjected to intense deformation and metamorphism in the orogenic setting since Late Devonian. However, the studies about deformation, metamorphism and superimposed mineralization in relation to VMS deposits are less constrained. In this paper, based on new field and laboratory researches on deposit geology, ore-forming fluids and geochemical characteristics in the Talate and Tiemurte Pb-Zn deposits, we present new insights of the ore genesis. In addition, the metallogenic model and ore prospecting are constructed in the end.The Talate and Tiemurte are the representative marine volcanic-sedimentary Pb-Zn deposits in the Kelan Basin, hosted in the metamorphic rock series of the lower Devonian Kangbutiebao formation. The mineralization is divided into two periods i.e., the submarine volcanic sedimentary exhalation period and the metamorphic hydrothermal overprinting period. The intense metamorphism had occurred in the Talate and Tiemurte Pb-Zn deposits in the Altay orogeny since Late Devonian, resulting in various deformations of the banded and laminated ores and wall rocks.In the Talate Pb-Zn deposit, the primary CO₂-H₂O inclusions in early quartz （Q1） and late quartz veins （Q2） have Th,,ot of 294～368℃ and 142～360 ℃, respectively, with the minimum trapping pressures of 100-370 MPa. The CO₂-rich inclusions in the Tiemurte Pb-Zn deposit have Th,tot of 180～³⁴2 ℃,with trapping pressures of 100～350 MPa, which suggest that the gold mineralization was derived from metamorphic fluid. The P-T trapping conditions of CO₂-rich fluids are consistent with those of late or post regional metamorphism.The δ⁶⁵Cu of the gold-bearing chalcopyrite from Tiemurte Pb-Zn deposit and Sarekuobu gold deposit suggest that the gold mineralization in the Tiemurte Pb-Zn deposit has the similar origin with Sarekuobu orogenic gold deposit. The δ66Zn of the sphalerite from marine volcanic-sedimentary deposits in the Kelan Basin indicate that the Pb-Zn deposits belong to VMS deposit. The Rb-Sr dating of sphalerite implys that the marine volcanic-sedimentary Pb-Zn deposits in the Kelan Basin formed in Early Devonian （392±92 Ma）, while the Rb-Sr isotopic age of pyrite and chalcopyrite from Sarekuobu gold deposit suggest that orogenic metamorphism occurred in the Late Permian to Triassic.The sulfur (δ³⁴S=-26.46‰～+4‰) was mainly derived from inorganic reduction of sulfates and bacteria sulfate reduction in seawater. The Pb isotopic compositions (²⁰⁶Pb/²⁰⁴Pb=16.86～18.073,²⁰⁷Pb/²⁰⁴Pb= 15.42-15.623, ²⁰⁸pb/²⁰⁴pb=37.27～38.097) indicate that the homogeneous Pb isotopes from sulfide are possible from the mixing of mantle material and surrounding rocks.The systematical studies show that the extensional basins after island arc along the southern margin of Altay Mountains might result from the subduction of the Erqis ancient Asia oceanic crust in Early Devonian, and then a number of marine volcanic-sedimentary Pb-Zn deposits formed from submarine exhalative-sedimentation. The orogeny of arc-continental collision in the Altay induced extensive deformation and metamorphism from Early Devonian to late Early Triassic, resulting in intense metal reworking and enrichment of early-forming VMS Pb-Zn deposits. The metamorphic fluids continuously extracted the Au from the volcanic stratigraphy with high value of Au, and gold was precipitated in the favorable places, i.e., Sarekuobu and Tiemurte.Based on study, the Pb-Zn deposits in the Kelan basin have further prospecting potential both in the length and depth of ore bodies. Moreover, Au （Cu） mineralization might be found in the sulfide-quartz veins due to intensive deformation and metamorphism.更多还原