摘要
杨山萤石矿床是豫西栾川地区一处大型花岗岩容矿型矿床,其成矿期次和成矿流体特征研究的不足长期制约着对萤石淀积机理和区域成矿规律的深化认识。本文基于杨山矿床萤石的稀土元素及流体包裹体研究,阐释了成矿物质来源、成矿流体属性及矿床成因。第Ⅱ阶段萤石的ΣREE含量为22.61×10^(-6)~287.94×10^(-6),LREE/HREE比值为0.64~5.24,具Eu负异常(δEu=0.50~0.92)和Ce负异常(δCe=0.88~1.06)。随成矿深度的增大,萤石ΣREE减小,LREE/HREE和La_(N)/Yb_(N)增大,δEu和δCe无明显变化,指示总体成矿先后顺序为地下深部至地表浅部,且垂向上氧逸度较稳定。从紫色萤石到绿色萤石,ΣREE增大,LREE/HREE和La_(N)/Yb_(N)减小,δEu和δCe增大,表明萤石具有重新活化和重结晶的趋势。萤石的流体包裹体以气液两相为主,均一温度集中于80~155℃,盐度(NaCl_(eqv.))集中于0.3%~6.3%。综合分析认为,杨山萤石矿床成矿流体以岩浆水和大气降水混合型为主,属低温、低盐度和低密度的NaCl-H_(2)O流体体系;矿床可归属于中低温、低盐度热液型矿床。萤石的稀土元素和流体包裹体特征综合分析表明,萤石的沉淀可能受水-岩反应控制。
The Yangshan fluorite deposit is located in Luanchuan County,Western Henan Province.The orebody is developed in the bottom of the Heyu granite,and is mainly controlled by NW-and NE-trending faults.Based on the study of rare earth elements and fluid inclusions of fluorite,the source of ore-forming materials,the ore-fluid properties and the ore genesis at Yangshan are discussed.TheΣREE content of stageⅡfluorite ranges from 22.61×10^(-6)to 287.94×10^(-6),LREE/HREE is of 0.64 to 5.24,and there are negative Eu anomalies(δEu=0.50-0.92)and Ce anomalies(δCe=0.88-1.06).With depth increases,ΣREE decreases,whereas LREE/HREE and La_(N)/Yb_(N)increase,andδEu andδCe do not change significantly.This indicates that the overall metallogenic time sequence is from deep to shallow,and the vertical oxygen fugacity is relatively stable.From the purple fluorite to green fluorite,ΣREE increases,LREE/HREE and La_(N)/Yb_(N)decrease,andδEu andδCe increase,indicating that recrystallization evolves from purple fluorite to green fluorite.The fluid inclusions of fluorite are mainly gas-liquid two phases.The homogenization temperature and salinity of these inclusions are concentrated in the range of 80-155℃and 0.3%-6.3%(NaCl_(eqv.)).Comprehensive analysis shows that the ore-forming fluid is mainly mixed with magmatic water and meteoric water,belonging to a low-temperature,low-salinity and low-density NaCl-H_(2)O system.Thus,Yangshan deposit is a low-temperature and low-salinity hydrothermal deposit.Comprehensive analysis of REEs and fluid inclusion characteristics of fluorite shows that the fluorite precipitation may have been controlled by water-rock reaction.
作者
王启博
张寿庭
唐利
李军军
盛渊明
WANG Qibo;ZHANG Shouting;TANG Li;LI Junjun;SHENG Yuanming(School of Earth Sciences and Resources,China University of Geosciences(Beijing),Beijing 100083,China;Luanchuan Natural Resources Bureau of Henan Province,Luoyang,Henan 471500,China)
出处
《现代地质》
CAS
CSCD
北大核心
2023年第6期1524-1537,共14页
Geoscience
基金
国家自然科学基金项目(41902193)
中央高校基本科研业务费项目(2652019191)
中央高校基本科研业务费项目(2652019047)。
关键词
萤石
成矿地质特征
稀土元素
流体包裹体
杨山矿床
fluorite
metallogenic-geological characteristic
rare earth element
fluid inclusion
Yangshandeposit
