长江中下游成矿带城门山斑岩-矽卡岩型铜金矿床碲元素赋存状态及沉淀机制初步研究  

Study of occurrence states and precipitation mechanism of tellurium in Chengmenshan porphyry-skarn deposit from the Middle-Lower Yangtze River Valley Metallogenic Belt

作　　者：国显正 周涛发[1,2] 汪方跃 叶少贞[3] 冯道水 GUO XianZheng;ZHOU TaoFa;WANG FangYue;YE ShaoZhen;FENG DaoShui(School of Resources and Environmental Engineering,Ore deposit and exploration Centre(ODEC),Hefei University of Technology,Hefei 230009,China;Anhui Province Engineering Research Center for Mineral Resources and Mine Environments,Hefei 230009,China;Northwest Geological Branch,Jiangxi Bureau of Geology and Mineral Resources,Jiujiang 332000,China)

机构地区：[1]合肥工业大学资源与环境工程学院,合肥工业大学矿床成因与勘查技术研究中心(ODEC),合肥230009 [2]安徽省矿产资源与矿山环境工程技术研究中心,合肥230009 [3]江西省地质矿产勘查开发局赣西北大队,九江332000

出　　处：《岩石学报》2021年第9期2723-2742,共20页Acta Petrologica Sinica

基　　金：国家自然科学基金项目(91962218);中央高校基本科研业务费专项(JZ2021HGQB0285、PA2019GDZC0093)联合资助.

摘　　要：碲是一种重要的战略性关键金属,主要以共伴生形式产出多个类型矿床中,斑岩-矽卡岩型矿床是碲资源重要的来源之一。城门山铜金矿床是长江中下游成矿带中一典型斑岩-矽卡岩型矿床,也是该区目前已报道的最大的共伴生碲矿床,然而碲在该矿床的赋存状态、碲的沉淀机制等尚不清楚。本文在详细划分成矿阶段基础上,对该矿床不同类型矿石中的矿物开展电子探针测试、LA-ICP-MS微量元素分析以及面扫描研究工作。测试结果表明碲元素主要以碲银矿、碲铋银矿等碲化物和辉碲铋矿、硫楚碲铋矿、碲黝铜矿等碲的硫化物形式存在,少量呈类质同象赋存在黄铁矿和黄铜矿中。黄铜矿中Te含量在矽卡岩型矿石中变化范围(0.15×10^(-6)~20.50×10^(-6))大于碳酸盐岩交代型矿石(0~3.44×10^(-6))。黄铁矿中Te含量在碳酸盐岩交代型矿石中最高,可达173×10^(-6);黄铁矿mapping显示在同一颗矿物中Te含量分布也不均匀。通过300℃logf_(Te2)-logf_(S2)相图分析,硫逸度介于-6.8~-11.4,碲逸度介于-7.8~-14.8;自花岗闪长斑岩向碳酸盐岩地层围岩,从成矿早阶段到晚阶段,硫逸度和温度逐渐降低,碲逸度升高,这是城门山矿床碲矿物沉淀的主要机制。城门山矿床中无论是单颗粒黄铁矿硫同位素还是原位硫同位素均显示岩浆来源特征,结合岩相学碲矿物与黄铁矿等硫化物密切共生,具有成因联系,表明碲的成矿物质来源也应为岩浆来源,与花岗闪长斑岩岩浆热液作用有关。Tellurium is an important critical metal,which mainly occurs in kinds of deposits in the form of byproduct.Porphyry and skarn deposit is one of the important sources of tellurium resources.Chengmenshan copper-gold deposit is a typical porphyry-skarn deposit in the Middle-Lower Yangtze River Valley Metallogenic Belt(MLYB),and it is also the largest reported byproduct tellurium deposit in MLYB.However,the occurrence state and precipitation mechanism of tellurium are not clear.In this study,we describe the detailed ore formation stages,and carry on the electron microprobe analyses,LA-ICP-MS trace element analysis and LA-ICP-MS mapping for minerals from different types of ores in the Chengmenshan deposit.The results show that the tellurium minerals are telluride and tellurium sulfide,such as hessite,volynskite,tetradymite,bismuth sulphurate,goldfieldite etc.,and a small amount tellurium element exists in pyrite and chalcopyrite in isomorphism.The chalcopyrite variation value of Te element in skarn is greater than that in carbonate metasomatic ores.The value of Te in pyrite is the highest in carbonate metasomatic ores,and up to 173×10^(-6);The distribution of Te content in the pyrite mineral is also inhomogeneous.Through 300℃logf_(Te2)-logf_(S2) phase diagram,the sulfur fugacity in the main metallogenic stage is between-6.8~-11.4 and the tellurium fugacity is between-7.8~-14.8.From the granite to the carbonate formation,the sulfur fugacity and temperature gradually decrease and the tellurium fugacity increases,which is the main mechanism of Telluride precipitation in Chengmenshan deposit.Both single grain pyrite sulfur isotope and in-situ sulfur isotope in Chengmenshan deposit show the characteristics of magmatic source.Combined with the tellurium minerals and pyrite and other sulfides,indicating that the metallogenic material source of tellurium should also be magmatic source,which is related to granodiorite porphyry magmatism.

关 键 词：碲 斑岩-矽卡岩型矿床 赋存状态 沉淀机制 城门山 

分 类 号：P618.83[天文地球—矿床学]