热液交代导致稀有金属铷在高分异花岗质岩石中富集OA北大核心CSTPCD

Fractional crystallization of granitic magmas and associated hydrothermal alteration are considered to control the enrichment of rubidium in granite-and pegmatite-type deposits.However,the role of hydrothermal alteration in enriching rubidium remains poorly understood.This study focuses on Xianglushan Rb deposit in northeastern Guangxi,where the Rb-bearing monzogranite,leucogranite,and greisen are well developed,to in-vestigate the role played by hydrothermal alteration in enrichment of rubidium.We performed major and trace elements analyses of Rb-bearing muscovite,potassium feldspar,plagioclase using an electron probe microana-lyzer and a laser ablation-inductively coupled plasma-mass spectrometer.The results indicate that the content of Rb in muscovite(3 826×10-6-9 100×10-6)is significantly higher than that in potassium feldspar(2 423×10-6-2 770×10-6)and plagioclase(0.61×10-6-57.80×10-6),and their contents are positively related to the con-tents of Li,B,and F.In addition,the incorporation of Rb into muscovite is facilitated by the substitution of K+and Na+.Relative to monzogranite,leucogranite and greisen formed from hydrothermal alteration of granitoids,greisen contains an elevated content of Rb2O(mean 0.193 2％).The results of this study support the model that hydrothermal replacement by Li-,B-,and F-rich fluids is a critical factor controlling the enrichment of Rb in granitic rocks in Xianglushan deposit.