Geochemical characteristics and tectonic settings of carboniferous volcanic rocks from Yili Region, western Tianshan
西天山伊犁地区石炭纪火山岩地球化学特征及构造环境

Carboniferous volcanic rocks are widespread at Yili region.Geochemical data of volcanic rocks from Axi,Gongnaisi and Qiaxi of Yili region suggests that they belong to calc-alkalic series,and consist of basalt,basaltic andesite,basaltic trachy-andesite, trachy-andesite and trachyte,which is the continued rock series from basic-intermediate-acid volcanic rocks.They are enriched in LREE relative to HREE,rich in Rb,Ba,Th,U,K and have a low concentrations of Nb,Ta,Ti.It suggests that they have a blood relation with volcanic-arc rocks and may be created by the sudbuction of the Junggar Ocean toward south beneath the Yili plate.The volcanic rocks from the south margin of the Yili plate could also be related to the subduction of the South Tianshan Ocean towards north beneath the Yili-Central Tianshan plate.