华北克拉通中部义兴寨金矿孙庄岩体的成因成矿作用:来自黑云母成分的约束OA

To elucidate the relationship between magmatic evolution and mineralization in the Yixingzhai gold deposit,western North China Craton,this study focuses on biotite from various lithologies of the Sunzhuang intrusion and conducts a detailed genetic mineralogical investigation.Petrographic observations and electron microprobe analyses were employed to systematically determine the major and halogen compositions of biotite,as well as to estimate its crystallization temperature,oxygen fugacity,and magma source characteristics.The results show that biotite from the Sunzhuang intrusion is characterized by high Mg and K but low Ti and Na contents,with MgO concentrations ranging from 13.4％to 17.8％,indicative of a crust-mantle mixed-source signature.Calculated crystallization temperatures range from 690 to 771℃,with logfO2 values between-17.1 and-14.9.In addition,the biotite is enriched in F,Cl and H2O.These geochemical characteristics suggest that the Sunzhuang intrusion was derived from a high-temperature,high-oxygen-fugacity,volatile-and halogen-rich magma formed by crust-mantle interaction.Such magmatic conditions favored the mobilization and enrichment of oxyphile metals such as Cu and Au,providing both the material source and thermal-fluid driving force for the formation of porphyry-type Cu-Au deposits.Consequently,the magmatism of the Sunzhuang intrusion is closely related to the metallogenesis of the Yixingzhai gold deposit.