关键词: 花岗岩, 垂直分带, 稀有金属矿化, 岩浆-热液演化, A型花岗岩

Abstract:

       The Laiziling granite stock was emplaced in the Early Yanshanian period. Its zircon U-Pb age is dated at (154-155)
Ma. This granite pluton is characterized by enrichment in Li, Rb, Sn, W, Nb, Ta etc. rare metal elements, Pb, Zn etc. base metal elements and H2O, F etc. volatiles. A vertical zonation  is well developed within a vertical distance of  (450~500) m. From  the deeper  level upwards  to  the  top of  the Laiziling Mountain peak,  the  following zones are successively observed: protolithionite granite zone, leucogranite (two-mica granite and Li-muscovite granite) zone, albite granite zone, greisen zone, massive quartz and pegmatoid stockscheider. Along this direction, the major and trace elements concentrations of rocks are regularly changed. Well developed magmatic fractionation and magmatic-hydrothermal evolution are responsible for high-degree enrichment of rare-metal elements, base metal elements and volatiles in the rocks and further mineralization. 
    Although most samples of the Laiziling granite stock exhibit peraluminous feature, the protolithionite granite at deeper level has high contents of Zr, REE, Y, Nb, Th, U etc. high field strength elements. Furthermore, relatively higher ε Hf values (from -5.9 to -1.9, averaging -4.2) and relatively lower Hf model ages (  tDM values from 1.32 Ga to 1.58 Ga, averaging 1.47 Ga) indicate an evident involvement of mantle materials. We propose that the primary magma source of the Laiziling granite might be derived from the A-type Qitianling batholith, or a fractionated deeper magmatic chamber similar to the Qitianling granite.

Key words:  granite, vertical zonation, rare-metal mineralization, magmatic-hydrothermal evolution, A-type granite granite, vertical zonation, rare-metal mineralization, magmatic-hydrothermal evolution, A-type granite