滇西北卓玛铅锌矿床成矿闪锌矿原位微量元素及硫化物原位硫同位素特征与地质意义  

Characteristics and geological significance of in-situ trace elements of sphalerite and in-situ sulfur isotope of the sulfides in the Zhuoma Pb-Zn deposit in Northwest Yunnan

作　　者：王乾鑫 冷成彪 李凯旋 王大钊 张兴春[3] WANG Qian-xin;LENG Cheng-biao;LI Kai-xuan;WANG Da-zhao;ZHANG Xing-chun(State Key Laboratory of Nuclear Resources and Environment,East China University of Technology,Nanchang 330013,China;School of Earth Sciences,East China University of Technology,Nanchang 330013,China;State Key Laboratory of Ore Deposit Geochemistry,Institute of Geochemistry,Chinese Academy of Sciences,Guiyang 550018,China)

机构地区：[1]东华理工大学核资源与环境国家重点实验室,江西南昌330013 [2]东华理工大学地球科学学院,江西南昌330013 [3]中国科学院地球化学研究所矿床地球化学国家重点实验室,贵州贵阳550018

出　　处：《岩石矿物学杂志》2024年第6期1361-1379,共19页Acta Petrologica et Mineralogica

基　　金：第二次青藏高原综合科学考察研究(2021QZKK0301)。

摘　　要：滇西北卓玛铅锌矿床位于甘孜-理塘结合带西侧的中甸地区,矿体产于卓玛中酸性复式斑(玢)岩中,以往的研究仅针对复式岩体中与石英二长斑岩相关的矿体开展工作,但对于石英闪长玢岩中的矿体研究较少。本次在详细的矿相学观察的基础上,对闪锌矿开展了激光剥蚀电感耦合等离子体质谱(LA-ICP-MS)原位微量元素分析,结合黄铁矿、磁黄铁矿、闪锌矿的原位S同位素分析,以期对矿床成因类型和成矿温度加以限定。研究发现,卓玛矿床闪锌矿以相对富集Fe、Mn和亏损Cd、Ga、Ge、In、Sn等元素为特征,其中Fe、Mn、Cd以固溶体的形式进入到闪锌矿中,部分Cu、Pb以矿物显微包体的形式存在,In与Cd结合形成微矿物的形式存在;本矿床硫化物的δ^(34)S组成介于-1.83‰~+2.30‰之间,闪锌矿Zn/Cd值在200~322之间,表明成矿物质来源与岩浆关系密切;硫同位素平衡温度计的计算结果为271~517℃,闪锌矿微量元素的GGIMFis温度计、FAS温度计和FA6温度计的计算结果分别在257±17~366±31℃、234~296℃和245~311℃之间。结合闪锌矿微量元素比值特征,认为卓玛矿床铅锌成矿物质沉淀于中温环境。在闪锌矿微量元素三角图和t-SNE图中,大部分测点落入与岩浆热液有关类型矿床的区域内,认为卓玛矿床产于复式斑岩顶部的铅锌矿体类型为浅成热液脉型。本研究为认识中甸地区的铅锌矿成因和勘查方向提供了地质地球化学依据。Zhuoma Pb-Zn deposit is located at the Zhongdian area on the western side of the Ganzi-Litang conjunction zone in northwest Yunnan.The ore is hosted in Zhuoma medium-acidic complex porphyry(porphyrite).Previous studies only focused on the ore bodies related to quartz-monzonite porphyry within the complex rock mass,but there is relatively little research on the ore bodies in quartz-diorite porphyrite.Based on mineralogical observations,in-situ trace elements analysis of sphalerite by laser ablation inductively coupled plasma mass spectrometer(LA-ICP-MS)was carried out.Combined with in-situ sulfur isotope analysis of pyrite,pyrrhotite,and sphalerite,it aims to determine the genetic type and ore-forming temperature of the deposit.The study found that sphalerite in the Zhuoma deposit is characterized relatively enriched Fe,Mn and depleted Cd,Ga,Ge,In and Sn.Among them,Fe,Mn,and Cd enter sphalerite in the form of solid solutions.Copper and Pb exist in the form of microscopic mineral inclusions,and indium exists in the form of micro-minerals combined with cadmium.Theδ^(34)S values of sulfides in this deposit ranges between-1.83‰and+2.30‰.The Zn/Cd ratio of sphalerite ranges from 200 to 322,indicating a close relationship between the source of ore-forming materials and magmatism.The calculation results of the sulfur isotope equilibrium thermometer are from 271℃to 517℃.The calculation results of the GGIMFis thermometer,the FAS thermometer and the FA6 thermometer for trace elements of sphalerite are 257±17~366±31℃,234~296℃and 245~311℃respectively.Combined with the characteristics of trace elements ratios of sphalerite,it is considered that the precipitation of Pb-Zn ore-forming materials in the Zhuoma deposit occurs in a mesothermal environment.In the sphalerite trace elements ternary diagrams and t-SNE plot,most of the measured points fall within the area of the deposit type related to magmatic hydrothermal fluids.It is considered that the lead-zinc ore body produced on the top of the complex porphyry in

关 键 词：卓玛铅锌矿床 闪锌矿 LA-ICP-MS 微量元素 成矿温度 

分 类 号：P578.2[天文地球—矿物学]