DISCUSSION ON THE METALLOGENETIC EPOCH AND ORE-FORMING MATTER SOURCE OF THE SILVER DEPOSITS IN YANSHAN AREA

The statistics and analysis on K-Ar ages and sulfur, lead and hydrogen-oxygen isotope data show that, the terrestrial volcanic-subvolcanic silver deposits in Yanshan area are obviously different from those in the eastern circum-Pacific belt. The metallogenetic epoch of the silver deposits in Yanshan area ranges from 195 to 100 Ma. The ore-forming matters are mainly deep-sourced, with addition of fundamental and cover material. The hydrothermal ore-forming solution is dominated by magmatic water mixed with meteoric water.