关键词: 花岗岩, 垂直分带, 锂, 稀有金属成矿, 香花岭地区

Abstract: Lithium (Li), one of strategic key metals, is mainly concentrated and crystallized in granitic rocks during magmatic stage. Owing to its incompatibility and volatile properties, Li has an important restriction on the petrogenesis and mineralization of granite. In this paper, the petrography, major-trace elements and mineralogy of Laiziling and Jianfengling granites in Xianghualing area (Hunan province), were systematically studied by means of electron microprobe analysis and LA-ICP-MS analysis. The results show: (1) during the crystallization differentiation of granitic magmas, the Li content increases gradually, which greatly reduces melt viscosity and increases crystallization temperature range, and granitic rocks were thus fully differentiated, resulted in the vertical zonation of granite; (2) in the granites Li contents have positive relationships with rare-metals’contents, and Li has synergistic mineralization with Ta, Nb and Sn etc.; (3) mica group minerals evolved to Li-rich phase (mainly zinnwaldite), with the crystallization of zinnwaldite, Nb, Ta and Sn etc. are successively precipitated, leading to decreasing contents of Ta and Nb in late mica. Although H2O, F, etc. in the melt have great influence on the properties and crystallization differentiation of granitic magma, but they are not enough to cause granite to be vertical zonation.

Key words: granite, vertical zonation, lithium, rare-metal mineralization, Xianghualing district