河北张三营碱长花岗岩铌铁矿族矿物特征及其意义  

Characteristics of columbite group minerals of the Zhangsanying alkali feldspar granite,Hebei Province,and its geological implications

作　　者：李亮 魏浩 赵二丽 王鹏 吕欣萍 赵克强 Li Liang;Wei Hao;Zhao Erli;Wang Peng;LüXinping;Zhao Keqiang(Hebei Province Collaborative Innovation Center for Strategic Critical Mineral Research,Hebei GEO University,Shijiazhuang 050031;Innovation Base for Mineralization Theory and Prospecting Technology of Ophiolite,Hebei GEO University,Shijiazhuang 050031;College of Earth Sciences,Hebei GEO University,Shijiazhuang 050031;Hebei Huakan Resource Environmental Survey Co.,Ltd.,Chengde,Hebei 067000;514 Brigade of North China Geological Exploration Bureau,Chengde,Hebei 067000;Institute of Geophysical and Geochemical Exploration,Chinese Academy of Geological Sciences,Langfang,Hebei 065000;Key Laboratory for Geochemical Exploration,Ministry of Natural Resources,Langfang,Hebei 065000)

机构地区：[1]河北省战略性关键矿产研究协同创新中心,河北地质大学,石家庄050031 [2]蛇绿岩带成矿理论与找矿技术创新基地,河北地质大学,石家庄050031 [3]河北地质大学地球科学学院,石家庄050031 [4]河北华勘资环勘测有限公司,河北承德067000 [5]华北地质勘查局五一四地质大队,河北承德067000 [6]中国地质科学院地球物理地球化学勘查研究所,河北廊坊065000 [7]自然资源部地球化学探测重点实验室,河北廊坊065000

出　　处：《地质科学》2024年第5期1453-1465,共13页Chinese Journal of Geology(Scientia Geologica Sinica)

基　　金：河北省自然科学基金项目(编号:D2020403103);河北地质大学博士基金项目(编号:BQ2017017)资助。

摘　　要：张三营碱长花岗岩位于华北克拉通北缘,岩体具高分异特征,整体富铌,具有一定的成矿潜力。为查明其含铌矿物种类及岩浆演化过程,本文对岩体中铌铁矿族矿物开展了显微结构和矿物化学研究。结果表明:铌铁矿族矿物是碱长花岗岩中最主要的含铌矿物,化学成分富铌(Nb)、贫钽(Ta),以铌铁矿为主,少量为铌锰矿,按成因分为岩浆期和岩浆—热液期两类。岩浆期铌铁矿族矿物数量多,矿物多自形且具振荡环带结构,推测结晶于岩浆过程;背散射电子图像中少量岩浆期铌铁矿族矿物出现“亮边”结构和成分反环带,暗示矿物受熔体交代作用影响。岩浆—热液期铌铁矿族矿物含量较少,化学成分均匀,Mn^(#)和Ta^(#)值相对较高,是从熔体中快速沉淀形成的。张三营碱长花岗岩岩浆演化经历了岩浆冷凝期、岩浆—热液过渡期和热液期。岩浆冷凝期历时较长,是岩体富铌的关键,岩浆—热液过渡期熔体对铌、钽富集起到一定的作用,热液期流体交代作用较弱,影响有限。The Zhangsanying alkali granite is located in the northern margin of the North China Craton.The whole rock is Nb-enriched and has a highly fractionated feature,showing a great rare metal metallogenetic potential.In this paper,we aim at identifying the species of Nb-bearing minerals and understanding the magma evolution process.We carry out a whole range of research on microstructure and mineral chemistry of columbite group minerals.The results illustrate that the columbite group minerals are the main Nb-bearing minerals,which have high contents of Nb and low contents of Ta and most are columbites-(Fe)with a small amount of columbites-(Mn).Geneses of the minerals are divided into magmatic and magmatic-hydrothermal types.The magmatic type of the columbite group minerals,numerous in quantity,is euhedral and has oscillatory zonation structures,indicating that they crystallize during magmatic process.Their BSE images show bright rim and reverse oscillatory zonation structures,implying melt metasomatism.The magmatic-hydrothermal type is fewer.They have homogenous chemical compositions,with higher Mn^(#)and Ta^(#),and they rapidly deposit from melt.The magma evolution of the Zhangsanying alkali granite involves magma cooling,magmatic-hydrothermal transition,and hydrothermal periods.The magmatism is crucial for Nb enrichment.The melt partly contributes to Nb and Ta enrichment during magmatic-hydrothermal transition period.Fluid metasomatism is weak during hydrothermal period and has few impacts on rare metal enrichment.

关 键 词：铌铁矿族矿物 岩浆演化 张三营 华北克拉通北缘 稀有金属 

分 类 号：P571[天文地球—矿物学] P574[天文地球—地质学]