新疆西天山阿尔恰勒Pb-Zn-Cu矿床成因——来自流体包裹体和同位素的证据  

Genesis of the Arqiale Pb-Zn-Cu Deposit in the Western Tianshan,Xinjiang:Evidence from Fluid Inclusions and Isotopes

作　　者：苏静 顾雪祥[1,2,3] 彭义伟[1,2,3] 沈宇凡 舒志平 梁清栋 王春山 陈曦 SU Jing;GU Xuexiang;PENG Yiwei;SHEN Yufan;SHU Zhiping;LIANG Qingdong;WANG Chunshan;CHEN Xi(College of Earth Sciences,Chengdu University of Technology,Chengdu 610059,Sichuan,China;Key Laboratory of Tectonic Controls on Mineralization and Hydrocarbon Accumulation,MLR,Chengdu University of Technology,Chengdu 610059,Sichuan,China;School of Earth Sciences and Resources,China University of Geosciences,Beijing 100083,China;Geological Team 703 of the Xinjiang Bureau of Nonferrous Metals,Yili 835000,Xinjiang,China;School of Geoscience and Technology,Southwest Petroleum University,Chengdu 610500,Sichuan,China)

机构地区：[1]成都理工大学地球科学学院,四川成都610059 [2]成都理工大学自然资源部构造成矿成藏重点实验室,四川成都610059 [3]中国地质大学(北京)地球科学与资源学院,北京100083 [4]新疆维吾尔自治区有色地质勘查局七〇三队,新疆伊犁835000 [5]西南石油大学地球科学与技术学院,四川成都610500

出　　处：《西北地质》2023年第1期81-98,共18页Northwestern Geology

基　　金：国家自然科学基金项目“新疆西天山北缘晚古生代斑岩-矽卡岩型铜钼铁多金属成矿与岩浆-热液作用过程”(42130804);“斑岩成矿系统中次浅成低温热液型矿床成矿机制研究:以新疆加曼特和小于赞金矿床为例”(41702081);成都理工大学珠峰研究计划项目“青藏高原及周缘矿产资源成矿规律、勘探及开发利用”(2020ZF11407)联合资助。

摘　　要：阿尔恰勒Pb-Zn-Cu矿床位于新疆西天山乌孙山脉西南缘,矿体产于下石炭统阿克沙克组灰岩中,其产状整体与地层基本一致。由于矿体具有层控特征,矿区地表和深部未见侵入岩体,导致该矿床与岩浆作用的关系尚不清楚。成矿过程大致可分为4个阶段:石榴子石-辉石阶段(I)、阳起石-黑柱石阶段(II)、石英-方解石-多金属硫化物阶段(III)和碳酸盐阶段(IV)。阶段Ⅱ阳起石与阶段Ⅲ石英、方解石和闪锌矿主要发育气液两相水包裹体(L-V型)以及少量单相液相水包裹体(L型)。阶段Ⅱ中阳起石L-V型包裹体均一温度和盐度分别为278~425℃和2.1~13.0 wt.%NaCl eqv,阶段Ⅲ热液矿物中L-V型包裹体均一温度和盐度分别为162~342℃和0.5~9.0 wt.%NaCl eqv。流体包裹体和C-H-O同位素组成特征显示,初始成矿流体主要为岩浆水,后期大气降水逐渐混入,导致成矿温度和盐度的降低以及矿物质的沉淀。矿石中硫化物的δ34S值变化范围较大(−7.57‰~1.30‰),Pb同位素具有壳幔混合特征。综合矿床地质、流体包裹体和同位素特征,推断阿尔恰勒属于远端矽卡岩型Pb-Zn-Cu矿床,其成矿物质具有深部岩浆和地层的混源特征。矿区内矿体由南侧浅部的Pb-Zn矿化逐步过渡到北侧深部的Cu±Zn矿化,暗示矿区北部深部可能存在隐伏的含矿岩体及接触带铜矿体。The Arqiale Pb-Zn-Cu deposit is located in the southwestern margin of the Wusun Mountain in the Western Tianshan,Xinjiang Province.The orebodies occur in the limestone of Lower Carboniferous Akeshake Formation and are generally consistent with the strata in occurrence.Considering that the orebodies are stratabound and no magmatic rocks are identified in the orefield,whether the deposit is related to magmatism remains controversial.Ore-forming process can be divided into four stages,including garnet-pyroxene stage(I),actinolite-ilvaite stage(II),quartz-calcite-polymetallic sulfide stage(III)and carbonate stage(IV).Two types of inclusions have been identified in the actinolite from stageⅡand quartz,calcite and sphalerite from stageⅢ,including the two-phase aqueous inclusions(L-V type)and mono-phase liquid aqueous inclusions(L type).The L-V type inclusions in actinolite have homogenization temperatures and salinities ranging from 278℃to 425℃and 2.1 wt.%NaCl eqv to 13.0 wt.%NaCl eqv,respectively.By contrast,the L-V type inclusions in stage III hydrothermal minerals have homogenization temperatures and salinities ranging from 162℃to 342℃and 0.5 wt.%NaCl eqv to 9.0 wt.%NaCl eqv,respectively.Fluid inclusions and C-H-O isotopic compositions indicate that the initial ore-forming fluids were mainly source from magmatic water,with increasing input of meteoric water with time,leading to the decrease of temperatures and salinities,as well as the precipitation of ore-forming materials.Theδ34S rations of sulfides in the ores have a wide range(−7.57‰~1.30‰),and the Pb isotopic compositions have the characteristics of crust-mantle mixing.Combined evidence from geology,fluid inclusions and S-Pb-C-H-O isotopes indicate that the Arqiale Pb-Zn-Cu deposit belongs to the distal skarn type deposit,with the ore-forming materials sourcing partially from the magmatic rocks at depth and partially from the strata.The orebodies in the ore field gradually transit from Pb-Zn orebodies at shallow in the south to Cu±Zn orebodi

关 键 词：流体包裹体 同位素 远端型矽卡岩矿床 阿尔恰勒 西天山 

分 类 号：P611[天文地球—矿床学] P597[天文地球—地质学]