Late Neoproterozoic to Early Paleozoic volcanism and iron-copper polyme-tallic mineralization of the Qilian Mountain

The most important period of tectonic evolution and mineralization in the Qilian orogenic belt is Late Neoproterozoic to Early Paleozoic. There are abundant iron-copper polymetallic ore deposits and they are closely related to the volcanism. According to the plate tectonic setting, the iron-copper polymetallic ore deposits can be grouped into four types:continental rift, island arc-is-land arc rift, continental margin rift and spreading ridge. The Jingtieshan-type iron-copper deposit was formed in the hot-water sedi-mentary mineralization of the volcanism in Late Neoproterozoic; the Donggou copper deposit was formed in an oceanic mid-ridge environment in Late Cambrian; the Baiyin orefield and the Qingshuigou-Bailiugou orefield were formed by the hot brine convec-tion and circulation related to the island arc-island arc rift volcanism during the Cambrian-Ordovician; the Shijuli copper deposit was formed in the back-arc spreading ridge in Late Ordovician; and the Honggou copper deposit was formed in a continental margin rift environment in Late Ordovician.