[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 materi-als,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 depos-its.Previous studies indicate that ore-forming fluids exsolved from alkaline magmas are characterized by low tem-peratures,high salinities and rich fluorine,which can lead to the super high enrichment of HFSEs and REEs in al-kaline 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 alter-ation in the late magmatic stage.The ore-forming materials were dominantly originated from mantle-derived mag-mas,crust-and mantle-derived magma mixing,or subducted oceanic crust.[Conclusions and Prospects]Hydro-thermal metasomatism and magmatic fractional crystallization are two enrichment mechanisms commonly used to in-terpret 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
Key words
alkaline granite/rare metal and rare earth element deposit/ore-forming fluid/ore-forming material/mineralization mechanism
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