浙江缙云骨洞坑萤石稀土地球化学与阴极发光特征  

Rare earth element geochemistry and cathodoluminescence characteristics of fluorite in Gudongkeng,Jinyun County,Zhejiang Province

作　　者：唐晓源 方乙[1,2] 王硕 代君瑶 王孟旭 TANG Xiaoyuan;FANG Yi;WANG Shuo;DAI Junyao;WANG Mengxu(School of Geoscience and Technology,Southwest Petroleum University,Chengdu 610500,Sichuan,China;Key Laboratory of Tectonic Controls on Mineralization and Hydrocarbon Accumulation,Ministry of Natural Resources,Chengdu 610059,Sichuan,China)

机构地区：[1]西南石油大学地球科学与技术学院,四川成都610500 [2]自然资源部构造成矿成藏重点实验室,四川成都610059

出　　处：《地球化学》2024年第2期293-308,共16页Geochimica

基　　金：自然资源部构造成矿成藏重点实验室开放基金项目(gzck202004)资助。

摘　　要：骨洞坑大型萤石矿床位于华夏古板块北东端,产出于下白垩统馆头组与燕山晚期花岗岩的接触带中。本文在地质调查基础上,对浙江缙云骨洞坑萤石矿床中的萤石进行阴极发光(CL)及原位稀土元素(REE)地球化学研究,以探讨缙云骨洞坑萤石矿床REE演化过程以及成矿物质来源。结果表明,骨洞坑萤石REE配分模式包括3种类型:“V”字型、重稀土元素(HREE)富集型和轻稀土元素(LREE)富集型。扫描电镜阴极发光(SEM-CL)图像显示,骨洞坑萤石发育不同类型的条带,早期萤石被晚期萤石交代,表明骨洞坑萤石经历了复杂的演化。萤石光学显微镜阴极发光(OM-CL)图像主要呈蓝色与绿色,可能与Sm^(3+)和Dy^(3+)的激活作用有关。单颗粒萤石原位分析结果显示,从核心到边缘,骨洞坑萤石的REE地球化学特征存在3种情况:①完全相同的REE配分模式和∑REE;②REE配分模式相同,但∑REE递减;③REE配分模式和∑REE都不相同。通过对比萤石样品与围岩REE配分模式,推断萤石REE具有多种来源,其与矿区内各类围岩密切相关,成矿流体受REE稳定性及络合作用影响,表现出与围岩不同的HREE富集特征。The Gudongkeng fluorite deposit is located in the northeastern part of the Cathaysia block.The orebodies occur in the contact zone between the Lower Cretaceous Guantou Formation and the Late Yanshanian granite.To explore the characteristics of REE and the source of ore-forming materials,the cathodoluminescence characteristics and REE geochemistry of fluorite from the Gudongkeng fluorite deposit in Jinyun,Zhejiang province,were investigated.The results show that fluorite from the Gudongkeng deposit exhibits highly varied chondrite-normalized REE patterns,including“V”type,HREE-enriched,and LREE-enriched patterns.The scanning electron microscope cathodoluminescence images of fluorite mainly show different bands.The early fluorite was replaced by the late fluorite,indicating a complex evolutionary history.The fluorite optical microcathode luminescence images are mainly blue and green,which may be related to the activation of Sm^(3+)and Dy^(3+)ions.In situ analysis of single-grain fluorite shows that fluorite in the deposit has highly varied REE contents and patterns,including:(1)uniform REE patterns and∑REE contents;(2)a core to rim decrease of∑REE contents with parallel REE patterns;and(3)highly varied REE patterns and∑REE contents from the core to the rim.By comparing the REE patterns of the fluorite samples and the surrounding rocks,it is concluded that fluorite has multiple REE sources,including the surrounding rocks in the mining area.The HREE enrichment of the ore-forming fluid may be due to the influence of the stability of REE species in the aqueous solutions.

关 键 词：骨洞坑萤石矿床 稀土元素 阴极发光图像 成矿流体 

分 类 号：P574[天文地球—矿物学] P595[天文地球—地质学]