ZENG Qing-wen1,2, MA Xing-hua1,2*, ZHANG Xin-yue3, SHU Qi-hai2
(1. MNR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China;
2. State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 10083, China;
3. College of Earth Sciences, Chengdu University of Technology, Chengdu 610059, China)
Abstract: The Qilishan gold deposit is located in the southwestern section of the Lingbei fault zone in the Jiaodong Peninsula, Shandong Province. It has relatively high Au grade of ores and relatively good potential for further gold prospecting in depth. Based on the detailed microscopic observation of micrstextures, electron probe micro analysis (EPMA) and mapping, we have carried out this study on the mineralogical assemblage and composition of gold-bearing minerals and occurrence state of gold of the deposit. The Qilishan gold deposit has mainly altered-rock type of ores, with minor quartz-vein type of ores locally. Four stages of its mineralization have been identified. Main metallic minerals in this deposit are native gold, electrum, pyrite, chalcopyrite, and galena, etc. Gangue minerals are mainly quartz, sericite, and calcite. The mineralization of gold mainly occurred in the quartz-pyrite stage and quartz-polymetallic sulfide stage. Gold mainly occurred as inclusion and intergranular particle in or near the pyrite and chalcopyrite grains. EPMA analyses show that Au contents of the native gold particles formed in the quartz-polymetallic sulfide stage (w(Au) > 90.0%) are apparently higher than those of gold particles formed in the quartz-pyrite stage (w(Au) = 77.9%－78.9%), implying that the ore-forming fluid of the intermediate stage was more enriched in Au concentration than that of the early stage with the hydrothermal evolution.
Keywords: Occurrence state of gold; EPMA; Qilishan gold deposit; Jiaodong Peninsula
ACTA MINERALOGICA SINICA Vol. 40, No.6, 2020, page 714-722
