METALLOGENIC PROCESS AND MODEL OF THE SUPER-LARGE YANGSHAN GOLD DEPOSIT IN GANSU PROVINCE

The Yangshan gold deposit is located in Wenxian, Gansu Province. Research on regional tectonic evolution and mineralizing chronology combined with field observation shows that there is a close spatial and temporal relationship between magmatic rocks and gold mineralization. The element content analysis of regional strata and gold ore confirms that the source bed of Yangshan gold deposit is Devonian Sanhekou formation. Further analysis on REE, stable isotope and fluid inclusion indicates that the sources of ore-forming substance of Yangshan gold deposit are complicated, with characters of both stratum and magmatite origin. The mineralizing fluid includes magmatic hydrothermal fluid, underground thermal brine, metamorphic hydrothermal fluid, atmospheric water and so on. Since Triassic period, several magmatic hydrothermal activities, which related to the regional tectonic evolution, have close relations with the gold mineralization of Yangshan gold deposit. It is concluded that Yangshan gold deposit underwent a complex mineralizing process of thermal brine mineralization and abyssal fluid mineralization. A mineralizing model of Yangshan gold deposit is therefore established on this basis.