滇东南板仑磁铁矿集区矽卡岩矿物学、地球化学特征及其形成机制  

Mineralogical, geochemical characteristics and formation mechanism of skarns in Banlun magnetite ore cluster area, southeastern Yunnan

作　　者：李睿昱 覃小锋[1,2] 王宗起 戴昱[5] 戴翔 毕婧怡 李东任 赵钰磊 LI RuiYu;QIN XiaoFeng;WANG ZongQi;DAI Yu;DAI Xiang;BI JingYi;LI DongRen;ZHAO YuLei(College of Earth Science,Guilin University of Technology,Guilin 541004,China;Guangxi Key Laboratory of Hidden Metallic Ore Deposits Exploration,Guilin University of Technology,Guilin 541004,China;Hydrogeology and Engineering Geology Brigade of Hubei Geological Bureau,Jingzhou 434020,China;Mineral Exploration Technical Guidance Center,Ministry of Natural Resources,Beijing 100083,China;Guangxi Institute of Regional Geological Survey,Guilin 541003,China)

机构地区：[1]桂林理工大学地球科学学院,桂林541004 [2]桂林理工大学广西隐伏金属矿产勘查重点实验室,桂林541004 [3]湖北省地质局水文地质工程地质大队,荆州434020 [4]自然资源部矿产勘查技术指导中心,北京100083 [5]广西区域地质调查研究院,桂林541003

出　　处：《岩石学报》2024年第4期1205-1230,共26页Acta Petrologica Sinica

基　　金：国家自然科学基金项目(42162007);中国地质调查局地质矿产调查评价项目(12120114039501);广西地质矿产勘查开发局地质勘查基金项目(桂地矿外任1号)联合资助。

摘　　要：位于华夏、扬子和印支板块交接部位的滇东南板仑磁铁矿集区属于个旧-文山-德保矽卡岩型锡钨多金属成矿带的重要组成部分。前人对该区矽卡岩型磁铁矿床的地质特征和矿床成因等进行了少量的研究工作,但对矽卡岩的成因尚缺乏系统的研究,这严重制约了对该矿集区内矽卡岩成因的认识及磁铁矿找矿潜力的准确评价。本文以矿集区内最为典型的坤洪和洞哈磁铁矿床的矽卡岩为主要研究对象,在对矽卡岩及相关岩石的野外地质特征和岩相学等方面进行详细研究的基础上,借助LA-ICP-MS和EPMA等方法手段,重点对矽卡岩及相关岩石的地球化学和矿物化学特征进行系统研究。结果表明,矽卡岩的成岩成矿演化过程可划分为早期进变质矽卡岩阶段、晚期退变质矽卡岩阶段和硫化物-碳酸盐阶段等3个阶段;(岩浆)热液成因的硅质岩条带与晚二叠世OIB型基性杂岩体(即“半瓦型”岩体)在原始地幔标准化微量元素蜘蛛网图和球粒陨石标准化稀土元素配分模式图上均存在显著的差异,而与中三叠世岛弧型中-基性杂岩体(即“安定型”岩体)的模式曲线较为相似,均显示出Nb、Ta、P和Ti等元素明显亏损的特征;矽卡岩的模式曲线与硅质岩条带的模式曲线也较为相似,且含矿矽卡岩比无矿矽卡岩无论在微量元素和稀土元素含量还是模式曲线上均更加接近于硅质岩条带。矿物化学的研究结果表明,第一世代石榴石属于钙铁-铁铝-钙铝榴石系列(And80-83Alm9-11Gro5-7),含较多的钙铝榴石(Gro);而第二世代石榴石属于钙铁-铁铝榴石系列(And86-93Alm6-12),基本上不含或仅含极少量的钙铝榴石(Gro);由早期辉石→晚期辉石,辉石端员组分中钙铁辉石所占的比例相对减少,而透辉石的含量则具显著增加趋势。综合分析认为,形成矽卡岩的热液流体主要来源于中三叠世岛弧型中-基性杂岩体;矽卡岩型磁铁�The Banlun magnetite ore cluster area in southeastern Yunnan, located at the junction of Cathaysian, Yangtze and Indosinian plates, is an important part of the Gejiu-Wenshan-Debao skarn type Sn-W polymetallic metallogenic belt. The predecessors have carried out a small amount of research work on the geological characteristics and genesis of the skarn type magnetite deposit in this area, but there is still no systematic study on the genesis of the skarn, which seriously restricts the further understanding of the genesis of skarns and the accurate evaluation of magnetite prospecting potential in this magnetite ore cluster area. This paper focus on the skarns and related rocks from the most typical Kunhong and Dongha magnetite deposits in Banlun magnetite ore cluster area. Based on the detailed study of the field geological characteristics and petrography of the skarns and related rocks, their geochemical and mineralogical characteristics are systematically studied by LA-ICP-MS and EPMA. The results show that the diagenetic and metallogenic evolution of skarns can be divided into three stages: early progressive metamorphic skarn stage, late degenerative metamorphic skarn stage and sulfide-carbonate stage;There are significant differences between siliceous rock bands of (magmatic-) hydrothermal origin and Late Permian OIB type basic complexs (namely "Banwa type" pluton) in primitive mantle-normalized spider diagrams and chondrite-normalized REE pattern diagrams;However, they are relatively similar to the model curves between siliceous rock bands of (magmatic-) hydrothermal origin and Middle Triassic island arc type intermediate-basic complexs (namely "Anding type" pluton), showing the characteristics of obvious depletion of Nb, Ta, P and Ti elements;The model curves of skarns are also similar to that of siliceous rock bands, and ore-bearing skarns are very close to siliceous rock bands than ore free skarns in terms of trace element contents and model curves. The research results of mineral chemistry show that the fir

关 键 词：矽卡岩 矿物学 地球化学 形成机制 板仑磁铁矿集区 滇东南 

分 类 号：P588.312[天文地球—岩石学] P618.31[天文地球—地质学]