LYU Jing-yi1,2, WANG Jin-hui1*, MAO Mei-qiao1, ZHANG Wen1, WANG Ying-peng1, YU Xiao-wei1, WANG Li-gong1, ZHANG Gui-li1

(1. Shandong Institute of Geological Survey, Jinan 250014, China;
2. China Communications Information Technology Group Co., Ltd, Beijing 100088, China)

Abstract: The Jiaodong gold deposit concentration area is the most important gold production base in China. The Haiyu gold deposit, located in the northern section of the Sanshandao gold metallogenic belt, is a newly discovered world-class gold deposit in the Jiaodong area in recent years. The source, nature and evolution process of the ore-forming fluid in this deposit are still unclear. Through petrographic observation, three metallogenic stages inclding the early metallogenic stage, the main metallogenic stage and the late metallogenic stage have been classified. Gold mineralization mainly occurred in the main metallogenic stage, and a small amount of gold mineralization occurred in the early metallogenic stage. Three types of fluid inclusions including the H2O-CO2 inclusion, CO2-rich inclusion and aqueous solution inclusion have been identified. Three types of fluid inclusions are observed in host minerals of both the early and the main metallogenic stages, while only the H2O-CO2 inclusion has been observed in host minerals of the late metallogenic stage. The fluid inclusions of the early, main and late metallogenic stages have homogenization temperatures of 310.9－360.5 ℃, 291.3－334.1 ℃ and 278.3－312.6 ℃, respectively, and salinities of 1.2%－18.0%, 0.8%－18.3% and 9.1%－18.0% (wt.% NaCl), respectively. Ore-forming fluids are characterized with medium-temperature, medium-low salinity, medium-acidic, and carbonaceous-rich properties. The fluid immiscibility generally occurred in the early and main stages. The gold precipitation was mainly resulted from the water-rock reaction and fluid immiscibility.

Keywords: Haiyu gold deposit; Ore-forming fluid; fluid inclusion; H-O isotopes

ACTA MINERALOGICA SINICA Vol. 43, No. 4, 2023, Page 521