Petrogenesis of ore-hosting magmatic rocks from the Jiudian gold deposit in Jiaodong area, and its geological implications

Jiaodong Peninsula is the most important and largest gold concentration area in China, and the Jiaodong gold resource is widely hosted by Linglong suites. Jiudian gold deposit is located at the junction of Jiaobei uplift and Jiaolai basin, which is an important part of Zhaoping fault, gneissic monzogranite is the main ore-hosting rocks, the study of petrogenesis can provide clues and constraints for exploring gold mineralization. In this paper, we carried out LA-ICP-MS zircon U-Pb dating and Lu-Hf isotopes of gneissic monzogranites around the Jiudian gold deposit. The analysis results show that the zircon Pb-206/U-238 ages are 160.1 +/- 1.1Ma, 160.37 +/- 0.7Ma, 161.04 +/- 0.4Ma and 162.2 +/- 0.9Ma, indicating that the Jiudian gold deposit contains strong magmatism in the Late Jurassic. The epsilon(Hf)(t) value in range of -31.9 similar to-20.8, and the two-stage Hf ages (t(DM)(2)) is 2996 similar to 2516Ma, indicating that the magma was sourced from partial melting of lower crust. The two-stage Hf age (t(DM)(2)) is corresponding to the magmatic activity caused by the addition of mantle materials and the juvenile crust. Therefore, the surrounding rock of the Jiudian gold deposit being derived from the partial melting of ancient mafic lower crust. The study shows that the formation of gneissic monzogranite may promote the activation of ore-forming materials in the Precambrian metamorphic basement, and the developing faults in the rock mass provide fit surrounding rock conditions for the formation of the deposit.