Geochemical Characteristics and Metallogenesis of Volcanic Rocks as Exemplified by Volcanic Rocks in Ertix,Xinjiang

Volcanic rocks in Ertix, Xinjiang, occurring in the collision zone between the Siberia Plate and the Junggar Plate, are distributed along the Ertix River Valley in northern Xinjiang. The volcanic rocks were dated at Late Paleozoic and can be divided into the spilite-keratophyre series and the basalt-andesite series. The spilite-keratophyre series volcanic rocks occur in the Altay orogenic belt at the southwest margin of the Siberia Plate. In addition to sodic volcanic rocks, there are also associated potassic-sodic volcanic rocks and potassic volcanic rocks. The potassic-sodic volcanic rocks occur at the bottom of the eruption cycle and control the distribution of Ph and Zn deposits. The potassic volcanic rocks occur at the top of the eruption cycle and are associated with An and Cu mineralizations. The sodic volcanic rocks occur in the middle stage of eruption cycle and control the occurrence of Cu(Zn) deposits. The basalt-andesite series volcanic rocks distributed in the North Junggar orogenic belt at the north margin of the Junggar-Kazakstan Plate belong to the potassicsodic volcanic rocks. The volcanic rocks distributed along the Ulungur fault are relatively rich in sodium and poor in potassium and are predominated by Cu mineralization and associated with An mineralization. Those volcanic rocks distributed alongthe Ertix fault are relatively rich in K and poor in Na, with An mineralization being dominant.