川西可尔因矿田高壤伟晶岩型锂矿床成矿地质特征及成因机制研究OA

As one of the key rare-metal mineralization clusters within the Songpan-Garzê orogenic belt,the Ke'eryin ore field hosts numerous pegmatite-type lithium deposits.Gaorang is a newly discovered cluster of spodumene-bearing pegmatite veins located in the northern part of the Ke'eryin ore field;while it possesses significant re-source potential,it remains relatively understudied,particularly regarding its genetic relationship with associated granites,which has yet to be clearly established.Muscovite serves as a ubiquitous accessory and rock-forming mineral within the Ke'eryin two-mica monzogranites and pegmatites,effectively recording compositional varia-tions within the melt.Consequently,this study focuses on the various types of pegmatites found in the Gaorang deposit,conducting comprehensive investigations involving whole-rock geochemistry,in situ micro-area compo-sitional analysis of muscovite,and Rayleigh fractionation modeling.The objective is to elucidate their genetic evolution and geological significance,thereby providing a theoretical basis for the prediction and exploration of pegmatite-type lithium deposits in this region.The research results indicate that the pegmatites of the Gaorang de-posit exhibit high contents of SiO2(63.98％～82.82％)and Al2O3(10.36％～21.39％);furthermore,their total alkali content and K/Na ratios vary significantly,classifying them as strongly peraluminous rocks.The albite-spodu-mene type pegmatites are relatively enriched in Li,Be,Nb,Ta,Rb,and Cs,while being relatively depleted in ele-ments such as Ba,Th,U,Ce,Sr,Nd,Sm,Zr,and Hf.Furthermore,they show relative enrichment in light rare earth elements(LREEs:La,Ce,Pr,Nd,Sm,Eu),distinct fractionation between LREEs and heavy rare earth ele-ments(HREEs),and a pronounced negative europium anomaly.A progressive trend of decreasing K/Rb,K/Cs,and Nb/Ta ratios in muscovite is observed across the sequence ranging from the two-mica monzogranites to the microline-albite type pegmatites,and finally to the albite-spodumene type pegmatites.Muscovite Rayleigh frac-tionation modeling reveals a clear magmatic evolutionary trend extending from the two-mica monzogranites to the pegmatites,suggesting that the pegmatitic magma at the Gaorang deposit likely originated through the frac-tional crystallization of a granitic magma,thereby pointing to a genetic origin rooted in magmatic differentiation.The study indicates that the pegmatite veins within the Gaorang deposit area are of substantial scale and exhibit favorable mineralization,suggesting promising prospects for mineral exploration.