碱性花岗岩结晶分异和岩浆不混溶过程与稀有稀土金属富集机制研究：以内蒙古巴尔哲超大型REE-Zr-Be-Nb-Ta矿床为例

与碱性花岗岩有关的稀有稀土矿床是关键金属产出的重要矿床类型之一，尽管国内外已对该类矿床开展大量研究，但有关结晶分异和岩浆不混溶过程对于金属富集机制的影响仍存有争议。本申请拟选取巴尔哲超大型稀有稀土矿床为研究对象，在野外地质、岩相学和矿物学研究基础上，开展矿区内成矿和未成矿岩体的熔体包裹体研究，重建两者P-T-X演化过程，查明成矿岩体强烈结晶分异和结晶相差异性饱和析出的主控因素，探讨成矿与未成矿的内在原因。开展熔体包裹体均一化实验，原位再现岩浆不混溶过程，获得与氟化物平衡的硅酸盐熔体实际组成和相应的P-T条件；以此为基础，开展实验岩石学模拟，查明岩浆不混溶发生机制；并分析氟化物和硅酸盐玻璃组成，确定成矿金属配分系数，定量分析岩浆不混溶对金属活动的制约。最终，从矿床地质、岩浆演化和实验模拟等多角度，揭示巴尔哲成矿与未成矿岩浆演化过程差异以及金属富集机制，为该类矿床成因和矿产勘查提供理论支撑。

The alkaline granite-related rare metal deposit is one of the important deposit types for critical metal production. Although much research has been carried out on this type of deposit, both domestically and internationally, there is still controversy about the controls of fractional crystallization and liquid immiscibility processes on metal enrichment mechanisms. The present application proposes to select the Baerzhe giant rare metal deposit as the study object. Based on the field geological, petrographic and mineralogical studies, a melt inclusion study of the mineralized and barren intrusions in the mine area will be carried out to reconstruct their P-T-X evolution processes, to identify the dominant controlling factors of extensive fractional crystallization and precipitation of different crystallizing facies, and to explore the intrinsic causes of the mineralized and barren intrusions. Then melt inclusion homogenization experiments will be conducted to reproduce in situ process of liquid immiscibility, and to obtain the actual composition of the silicate melt in equilibrium with fluoride and the corresponding P-T conditions. Based on these results, a synthetic experimental study will be conducted to identify the mechanism of fluoride-silicate melt immiscibility. And the compositions of fluoride and silicate glasses will be subsequently analyzed to determine the partition coefficients of ore-forming metals and quantify the constraints of liquid immiscibility on metal activity. Ultimately, the intrinsic differences in the process of magmatic evolution and the mechanism of metal enrichment between Baerzhe mineralized and barren magmas can be revealed from multiple perspectives, including the geology of the deposit, magma evolution and experimental simulation, providing theoretical support for the genesis and mineral exploration of this type of deposit.