College of Earth Sciences, Jilin University, Changchun 130061, China

Petrography,LA-ICP-MS zircon U-Pb dating and geochemical data of biotite granodiorite in Nancuo Cu-Au mining area related to mineralization have been studied.The results show that the diagenetic age of the biotite granodiorite is 153.40 ±0. 67 Ma,belonging to Late Jurassic.And the biotite granodiorites are calc-alkalineseries and quasi aluminum to peraluminous rocks. There is significant fractionation between LREE and HREE,with La_N/Yb_N=9.31~12.65,and there is positive anomaly for Eu,with ��Eu=1.21~1.66. For trace elements,the biotite granodiorite is enriched in LILE for K and HFSE for Sr, Zr. But depleted in HFSE for U, Nb, Ce, Nd and P.Characteristics of I type granite are presented in the rock mass. The Zr/Hf value of the sample is 42.23~45.82,with an average of 44.2,the ratio of Rb/Sr is 0.07~0.19,with an average value of 0.13,and the value of Nd/Th is 1.65~2.18,with an average of 1.99,indicating crust derived magma with mantle materials mixed. The Mg^# value of the sample is 49.80~57.22,the Sr value is 443.3~874.9,the Yb value is 0.80~1.39,the Y value is 8.96~16.60,and Na₂O/K₂O > 2(2.18~2.97),indicating oceanic crust adakites,with a small amount of mantle wedge material mixed during the rising process. Combined with previous research,it is suggested that the granodiorite formed in volcanic arc environment during northward subduction of Bangonghu-Nujiang oceanic basin,in Late Jurassic.