碱性花岗岩型稀有稀土矿床类型及成矿作用研究进展  

Research advances on mineralization and types of the alkaline granite-related rare metal and rare earth element deposits

作　　者：季浩 李艳军[1] 李一鸣 冷双梁 杨紫文 JI Hao;LI Yanjun;LI Yiming;LENG Shuangliang;YANG Ziwen(School of Earth Resources,China University of Geosciences(Wuhan),Wuhan 430074,China;Hubei Geological Survey,Wuhan 430034,China;Hubei Research Center of Geological Exploration and Engineering Technology,Wuhan 430034,China)

机构地区：[1]中国地质大学(武汉)资源学院,武汉430074 [2]湖北省地质调查院,武汉430034 [3]湖北省地质勘查工程技术研究中心,武汉430034

出　　处：《地质科技通报》2024年第1期23-38,共16页Bulletin of Geological Science and Technology

基　　金：中国地质大学(武汉)中央高校基本科研业务费项目(CUGCJ1817);国家自然科学基金项目(42172084);湖北省地质局项目(KCDZ-2022015;KJ2022-48)。

摘　　要：碱性花岗岩因富集稀有稀土元素而成为一种重要的成矿岩体。近年来碱性花岗岩型稀有稀土矿床在矿床类型分类、成矿流体和成矿物质来源及成矿机制等方面取得一些重要的研究进展。碱性花岗岩通常富集高场强元素(HFSEs)和稀土元素(REEs),根据暗色矿物与主矿种之间的关系该类型矿床可分为富Nb-Zr-REEs钠(铁)闪石碱性花岗岩型、富Nb-U-HREEs碱性杂岩型和富Nb-Sn黑云母碱性花岗岩型3种类型。碱性花岗岩型稀有稀土矿床成矿时代主要集中于古生代-新生代,与大陆、超大陆的裂解和聚合后期伸展构造背景有关。成矿流体经历了早期岩浆分异与晚期热液交代2个演化阶段。研究表明从岩浆中出溶的成矿流体具有低温、高盐度、富F等特征,可导致HFSEs和REEs等元素在碱性花岗岩中超常富集。母岩浆中不相容元素浓集到出溶流体中,并随着后期含F流体结晶或交代原岩而形成稀有稀土矿物。成矿物质通常来源于地幔岩浆或地幔与地壳的混合,但也可能来源于俯冲洋壳。岩浆结晶分异与热液交代为碱性花岗岩型稀有稀土矿床的2种主要成矿机制,但该类矿床大多为2种机制的复合形成。[Significance]Alkaline granites are one of the most important intrusions associated with rare metal and rare earth element mineralization.[Progress]Recently,alkaline granite-related rare metal and rare earth element deposits have achieved a number of important advances in classification,sources of ore-forming fluids and materials,and enrichment mechanisms.Alkaline granites are usually enriched in high field strength elements(HFSEs)and rare earth elements(REEs).These deposits can be divided into three types based on the relationships between mafic and oreminerals,i.e.,arfvedsonite alkaline granite-related Nb-REE deposits,biotite alkaline granite-related Nb-Sn-rich deposits,and nepheline/aegirine syenite-related Nb-U-REE-rich deposits.Mineralization ages of these deposits are concentrated in the Paleozoic-Cenozoic.The deposits are formed in an extensional setting associated with break-up and convergence of continents and supercontinents.Two stages of ore-forming fluids,early-stage magmatic differentiation and late-stage hydrothermal metasomatism,are recognized for the formation of these deposits.Previous studies indicate that ore-forming fluids exsolved from alkaline magmas are characterized by low temperatures,high salinities and rich fluorine,which can lead to the super high enrichment of HFSEs and REEs in alkaline granites.Incompatible elements in parental magmas can be enriched in exsolved fluids and can lead to the formation of rare metal and rare earth element ores due to F-rich fluid fractional crystallization or hydrothermal alteration in the late magmatic stage.The ore-forming materials were dominantly originated from mantle-derived magmas,crust-and mantle-derived magma mixing,or subducted oceanic crust.[Conclusions and Prospects]Hydrothermal metasomatism and magmatic fractional crystallization are two enrichment mechanisms commonly used to interpret the formation of these deposits.However,most of these deposits are formed by a combination of the two mechanisms.

关 键 词：碱性花岗岩 稀有稀土矿床 成矿流体 成矿物质 成矿机制 

分 类 号：P618.7[天文地球—矿床学] P588.15[天文地球—地质学]