Abstract:There are multiperiodic magmation and W-Sn mineralization in Xitian region, Eastern Hunan province, The Indosinian granite mineralization was relatively weak, while the Yanshanian granite mineralization was pronounced. The critical factors controlling the difference in the potential of W-Sn mineralization between the two periods of granite are still unclear. In this paper, we report Zircon U-Pb chronology, Zircon Lu-Hf isotope data, whole rock geochemistry and mineral composition for Indosinian and Yanshanian granites in Xitian region. The zircon LA-ICP-MS U-Pb dating yielded magmatic crystallization ages of 240.0±1.3Ma and 152.9±1.0Ma, corresponding to the Indosinian and Yanshanian periods, respectively. Both periods of granite are characterized by high Al2O3 contents, low MgO contents, enriched in Rb, K, U, Th and depleted in Ti, P, Sr, Ba, Nb. The Zircon εHf(t) values (concentrated between -7.0 and -5.0) and melting temperature(>750℃) of the two periods of granite are similar, The Zircon TDM2 values of Indosinian granite and Yanshanian granite are concentrated at 1.65-1.70Ga, 1.55-1.60Ga, suggesting a magmatic source which was partial melting of ancient crust of the Paleoproterozoic era at high temperature, but the source rocks of the Yanshanian granites are younger than Indosinian granites. The whole-rock Zr/Hf ratios of Indosinian and Yanshanian granite are 26.1-36.3 and 7.0-22.7, and the Nb/Ta ratios are 3.9-7.6 and 1.2-3.9, suggesting that both of them have experienced high differentiation evolution. The magma oxygen fugacity of the Indosinian granite (ΔFMQ=-0.42~2.61) is higher than that of the Yanshanian granite (ΔFMQ=-2.33~-0.08). The Ⅳ(F) of biotite indicates that Indosinian granites have lower concentration of F (Ⅳ(F)=1.15~1.26) than Yanshanian granites (Ⅳ(F)=0.71~0.87). Consequently, more enriched magmatic source region, lower oxygen fugacity and higher F abundance may be the main reasons why Yanshanian granites have more pronounced mineralization than Indosinian granites.