粤北书楼丘矿床围岩蚀变特征与流体成矿作用  

Study on characteristics of wall rock alteration and fluid mineralization in Shulouqiu deposit,northern Guangdong

作　　者：孙国权 范洪海 高永宝 范堡程 薛春纪[3] 庞雅庆[2] 马承 SUN GuoQuan;FAN HongHai;GAO YongBao;FAN BaoCheng;XUE ChunJi;PANG YaQing;MA Cheng(Xi’an Center of Mineral Resources Survey of China Geological Survey,Xi’an 710100,Shaanxi,China;CNNC Key Laboratory of Uranium Resource Exploration and Evaluation Technology,Beijing Research Institute of Uranium Geology,Beijing 100029,China;School of Earth Sciences and Resources,China University of Geosciences,Beijing 100083,China)

机构地区：[1]中国地质调查局西安矿产资源调查中心,陕西西安710100 [2]核工业北京地质研究院铀资源勘查与评价技术重点实验室,北京100029 [3]中国地质大学地球科学与资源学院,北京100083

出　　处：《矿床地质》2022年第2期345-358,共14页Mineral Deposits

基　　金：中国地质调查局项目“全国金矿资源潜力评价(编号:030301)”;中核集团集中研发项目(编号:LTD1602)联合资助。

摘　　要：文章以粤北长江铀矿田书楼丘矿床矿体外围蚀变岩石为研究对象,系统地将流体水岩作用导致的蚀变划分为4期11种类型。以各类蚀变在水平方向的发育程度、组合变化等为依据,将蚀变岩划分为矿化中心带、矿旁强蚀变带、矿旁弱蚀变带、正常花岗岩4个分带。以各分带蚀变岩石岩相学、矿物学、岩石学以及元素地球化学特征变化为依据,探讨流体作用与铀成矿的关系。研究表明,矿化中心带以硅化+赤铁矿化+黄铁矿化+紫黑色萤石化+肉红色碳酸盐化蚀变组合、Li+Pb+W+Mo+Bi元素正异常组合和Sr+Ba+Th+Zr元素负异常组合为特征,对找矿具有很好的指示意义。成矿流体为富含Si、Ca、Fe、S、U、∑CO_(2)的壳幔混合流体,多期流体作用致使各蚀变带内轻稀土元素不同程度迁出,矿化中心带稀土元素之间出现“均一化”现象。岩体为成矿提供了铀源,区域上中基性岩脉的就位可能为成矿系统提供了还原环境。书楼丘矿床的成矿流体壳源成分占比高于棉花坑矿床,整体水-岩作用相对较弱,蚀变带发育程度不如后者,造成二者成矿能力的差异。This paper takes the altered rocks at the periphery of the Shulouqiu uranium deposit as the research object in the Changjiang uranium ore field,northern Guangdong Province,systematically dividing the alterations caused by fluid water-rock reaction into four periods and eleven types.Based on the alteration intensity and assemblage changes of alterations in a plan view,the altered rocks hosting the ore bodies are divided into four zones outwards:the central zone of mineralization,the strong alteration zone,the weak alteration zone,and the normal granite.Based on changes in the characteristics of petrography,mineralogy,petrology,and element geochemistry of the altered rocks within each alteration zone,the relationship between fluid interaction and uranium mineralization in each period is discussed.The study shows that the central zone is represented by a combination of silica+hematite+pyrite+purple dark fluorite+pale-red carbonate alteration,positive composite anomaly of Li+Pb+W+Mo+Bi,and negative composite anomaly of Sr+Ba+Th+Zr,all are good indications of mineralization.The oreforming fluid is rich in Si,Ca,Fe,S,U and∑CO_(2)with a crust-mantle mixed source.The multi-period fluid waterrock interaction causes that the LREE were migrated out from each alteration zone at different degrees,resulted in the phenomenon of"homogenization"among the rare earth elements in the central zone of mineralization.The intrusive rock provides a source of uranium for mineralization,and the existence of intermediate-basic dykes in the region may provide a reducing environment for the mineralization system.The Shulouqiu deposit has a higher proportion of crust-source ore-forming fluid components than the Mianhuakeng deposit,the overall water-rock interaction is relatively weak,and the development intensity of alteration zone is not as good as that of the Mianhuakeng deposit,which results in the difference of ore-forming ability between them.

关 键 词：地质学 水平蚀变分带 元素迁移规律 流体作用机制 书楼丘矿床 

分 类 号：P619.14[天文地球—矿床学]