江西宜春雅山岩体位于钦杭成矿带东段萍乡-绍兴结合带西端,是华南地区最重要的铌钽矿化稀有金属花岗岩之一(杨泽黎等,2014)。矿区主要出露地层包括新元古界板溪群、震旦系和寒武系千枚岩和变质砂岩,岩体侵位于其中的震旦系变质砂岩中(Yin et al.,1995)。锆石U-Pb同位素定年表明,雅山岩体的形成年龄为约155 Ma,属于燕山早期岩浆活动的产物。雅山岩体为一经多阶段演化形成的复式花岗岩体,岩体从早到晚、从下而上至少可分为:(1)
Mesozoic granitic intrusions are widely distributed in the Nanling region, South China. Yanshanian granites are closely connected with the formation of tungsten deposits. The Xihuashan granite is a typical representative of tungsten-bearing granite. The Xihuashan granite consists mainly of medium-grained porphyritic biotite granite, medium-grained biotite granite and fine-grained twomica granite, which correspond to LA-ICP-MS zircon U-Pb ages of 555.5±0.4 Ma, 553.0±0.6 Ma and 552.8±0.9 Ma, respectively. Rocks from the Xihuashan mining area displays high SlOe （73.85% to 76.49%） and NaeO＋K20 contents （8.09% to 9.43%）, belonging to high-K calc-alkaline series. They are metaluminous to weakly peraluminous with A/CNK values ranging from 0.96 to 5.06. All granites in this study area are rich in Rb, Th, U and Pb, and depleted in Ba, Sr, P, Ti, Nb and Eu, especially depleted in medium-grained biotite granite and fine-grained two-mica granite. The medium-grained porphyritic biotite granites usually have high LREE concentrations, whereas medium-grained biotite granite and fine-grained two-mica granite displays high HREE contents. Our geochemical data reveal that the studied rocks are highly fractionated I-type granite. The magma underwent strong magma differentiation with decreasing temperature and increasing oxygen fugacity, which may explain the formation of three types of distinct granites. Variations of Rb, Sr and Ba concentrations in different type granites were controlled by fractional crystallization of biotite and feldspar. Fractional crystallization of monazite, allanite and apatite resulted in LREE changes in granite, and formation of garnet mainly caused HREE changes. Granites from the Xihuashan mining area have relatively high εd（t） values （-9.77 to -55.46）, indicating that they were probably generated by partial melting of underlying Proterozoic metasedimentary rocks with minor addition of juvenile crust or mantlederived magmas.
YANG JiehuaPENG JiantangZHAO JunhongFU YazhouYANG ChenHONG Yinglong
