Abstract: Leucogranite is one of the mineral components of the Cuonadong dome core located in the eastern part of the Himalayan orogenic belt. LA-ICP-MS zircon U-Pb dating yielded crystallization ages of 20.6±0.3 Ma and 16.7±0.2 Ma for two-mica and garnet-bearing muscovite granites, respectively, in accordance with the Miocene Himalayan leucogranites. The characteristics of both leucogranites feature high SiO2 (71.6%74.6%), Al2O3 (14.5%16.1%), and K2O (4%4.7%) contents with A/CNK of 1.161.22, suggesting the leucogranites belong to high-K calc-alkaline and strongly peraluminous granites that are enriched in Rb, U, K, and Pb and relative depleted in Nb, Ta, Zr and Ti. Garnet-bearing muscovite granites have strong negative Eu anomalies (Eu/Eu* between 0.29 and 0.46), while relatively weak negative Eu anomalies (Eu/Eu* between 0.58 and 0.80) were found in two-mica granites. Two-mica granites have Rb/Sr ratios of 2.43.5, Ba contents of (200253)×10-6, and relatively low TiO2 contents, likely formed from muscovite dehydration melting of metapelites under the decompression condition caused by the movement of the STDS. Garnet-bearing muscovite granites, on the other hand, show non-chondritic anomalies in K/Rb, Zr/Hf, Nb/Ta and Y/Ho ratios, REE tetrad effects, and abnormally high Rb/Sr ratios (18.622.2)—all features of highly evolved granites favoring mineralization of rare metal elements such as W, Sn, Be, etc. Meanwhile, garnet-bearing muscovite granite pluton is adjacent to the W-Sn-Be ore deposits within the Cuonadong dome, raising the likelihood that the occurrence of the garnet-bearing muscovite granite might contribute to W-Sn-Be mineralization. Likewise, common spatiotemporal patterns are shared by two-mica granites and Zhaxikang Pb-Zn deposits, an indication that a genesis relationship may exist between the two.

Key words: Cuonadong leucogranite, petrogenesis, highly fractionated granite, muscovite dehydration melting, Zhaxikang Pb-Zn deposits