Tectonic-Magmatic Evolution and Gold Mineralization in Yangshan Gold Belt,Gansu Province,China

Yangshan gold deposit is located in Wenxian County, Gansu Province.Geochronology study shows that three magmatic-hydrothermal events happened in the ore district respectively in Early Jurassic,Early Cretaceous and Early Tertiary.Stable isotope analysis shows that δD value of fluid inclusions in mineralized quartz veinlet ranges from-75‰ to-56‰,δ~(18)O_(H_2O)value ranges from 3.7‰ to 12.2‰,and δ~(34)S value of pyrite and stibnite ranges from-2.2‰ to-0.7‰,indicating that metallogenic materials and ore fluid are mainly from the magmatic events.Analysis of tectonic deformation indicates that ductile deformation occurred in Triassic Period,ductile-brittle deformation occurred in Early Jurassic,while brittle deformation occurred after Jurassic Period.The brittle deformation experienced early pression period and late tension period.By comparing the tectonic-magmatic events with the regional tectonic evolusion,we propose that the coupling of three magmatic-hydrothermal events affected by regional extension contributed to mineralization of Yangshan gold deposit.