| Abstract:The Rushan gold deposit, one of the recently-proven large gold deposits in east Shandong, lies in the central part of the Muping-Rushan gold metallogenic belt. Based on research work in such aspects as regional geology, ore deposit geology, wall rock alterations, ore types, ore minerals, ore-forming stages, thermometry and gas-liquid composition of inclusions in quartz, and hydrogen-oxygen isotopic geochemistry, the author has reached the following conclusions: 1. The Rushan gold deposit is a postmagmatic mesothermal pyrite quartz-vein type gold deposit related to Mesozoic Kunyushan granite. 2. The ore-control structure is a compound structure formed by two sets of faults trending respectively N 15°E and N 65°E. 3. From potassic alteration to the formation of siderite quartz veins, the ore-forming process experienced four stages, in which the formation of pyrite quartz veins and phyllic rock seemed to be the major stage whose formation temperature, pressure and oxygen fugacity(logfO2)being 295～311℃, 7.58×104～7.77×104 KPa and -33.3～-35 respectively. 4. The ore-forming substances were derived from Jiaodong Group, and the weak acid ore-forming hydrothermal solutions rich in Fe2+, SO4-2, HCO3- and CO2 evolved from postmagmatic weak alkaline hydrothermal solutions rich in K+, Na+ and Cl. 5. Gold occurs in pyrite and its cracks as micrograined native gold, electrum and petzite, associated with altaite and tellurobismuthite. |
