云南个旧锡多金属矿集区电气石地球化学组成和硼同位素特征——对成矿流体性质和演化的约束  

Geochemical Composition and Boron Isotope Characteristics of Tourmalines in the Gejiu Tin Polymetallic Mining Area,Yunnan Province:Constraints on the Properties and Evolution of Ore-forming Fluids

作　　者：任竑宇 李超[3,4] 江小均 杨富成[1,2] 韩嶂 芦磊 陈耀坤 REN Hongyu;LI Chao;JIANG Xiaojun;YANG Fucheng;HAN Zhang;LU Lei;CHEN Yaokun(Department of Earth Sciences,Faculty of Land Resources Engineering,Kunming University of Science and Technology,Kunming,Yunnan 650093;Key Laboratory of Sanjiang Metallogeny and Resources Exploration and Utilization,Ministry of Natural Resources,Kunming,Yunnan 650051;National Research Center for Geoanalysis,Beijing 100037;Key Laboratory of Re-Os Isotope Geochemistry,China Geological Survey,Beijing 100037;Datun Tin Mine of Yunnan Tin Company Limited,Gejiu,Yunnan 661000;Laochang Branch of Yunnan Tin Company Limited,Gejiu,Yunnan 661400)

机构地区：[1]昆明理工大学国土资源工程学院地球科学系,云南昆明650093 [2]自然资源部三江成矿作用及资源勘查利用重点实验室,云南昆明650051 [3]国家地质实验测试中心,北京100037 [4]中国地质调查局Re-Os同位素地球化学重点实验室,北京100037 [5]云南锡业股份有限公司大屯锡矿,云南个旧661000 [6]云南锡业股份有限公司老厂分公司,云南个旧661400

出　　处：《地球学报》2024年第4期575-590,共16页Acta Geoscientica Sinica

基　　金：云南省科技计划项目(编号:202202AG050006);云南省科技计划项目高层次科技人才及创新团队选拔专项(编号:202305AT350004)联合资助。

摘　　要：个旧锡矿集区发育与晚白垩世高分异花岗岩有关的世界级Sn-Cu多金属矿床,其成矿物质的来源及流体演化过程一直是研究的热点和难点。个旧地区电气石广泛发育于碳酸盐岩、花岗岩及矽卡岩中,但对电气石尚未进行系统研究,电气石与成矿之间的关系尚未明确。本文对不同类型电气石开展了系统的岩相学观察和电子探针(EPMA)、LA-ICP-MS微量元素和硼同位素分析。结果表明,所有电气石都属于碱性电气石,TurⅠ、TurⅡ、TurⅣ为热液成因,TurⅢ为岩浆成因。岩浆电气石相比于热液电气石具有更低的Mg、Ca等元素,TurⅠ电气石高含量的Sr表明受到了围岩的混染。电气石的微量元素变化表明,从似斑状花岗岩到等粒花岗岩,随着岩浆分异程度逐渐增加,Sn在岩浆中逐渐富集,在似斑状花岗岩和接触带矽卡岩中沉淀卸载。个旧不同类型电气石具有均一的δ11B值(−15.2‰~−12.8‰),与花岗岩的组成范围一致,表明成矿物质来源均来源于花岗质岩浆。The Gejiu tin deposit is a world-class Sn-Cu polymetallic deposit related to highly differentiated granite in the Late Cretaceous.Its mineral origin and fluid evolution process have always been the focus of research.Tourmaline is widely developed in carbonate rock,granite,and skarn in the Gejiu area;however,the relationship between tourmaline and mineralization is unclear.In this study,systematic petrographic observation and electron Microanalysis(EPMA),and LA-ICP-MS analysis of trace elements and boron isotopes from different types of tourmaline were carried out.The results show that all tourmalines belong to basic tourmaline;TurⅠ,TurⅡ,and TurⅣare of hydrothermal origin,whereas TurⅢis of magmatic origin.Compared with hydrothermal tourmaline,magmatic tourmaline has lower Mg,Ca,and other elements and the high Sr content of TurⅠtourmaline indicates that it was contaminated by the surrounding rock.The variation in trace elements in the tourmaline reveals that Sn was gradually enriched in the magma and precipitated in the porphyritic granite and contact skarn,with an increasing degree of magmatic differentiation from porphyritic granite to equite-grained granite.The different types of tourmalines had uniformδ11B values(−15.2‰–−12.8‰),which are consistent with the composition range of granite,indicating that the ore-forming materials were derived from granitic magma.

关 键 词：电气石 硼同位素 岩浆-热液型锡多金属矿床 个旧锡矿矿集区 

分 类 号：P595[天文地球—地球化学]