The post-collisional granites of late Paleozoic Era widely spread in west Junggar, and most of them were formed in 300Ma, the era of the late Carboniferous. A-type granite consists of high silicon, low aluminum, rich alkali, metaluminous-weakly peraluminous, poor calcium and low magnesium; 10000 Ga/Al ratio was fairly high; high field strength elements (HFSE) and Zr, Y, Ga, etc. are intensively concentrated; Sr and Ba are strongly depleted; REE assemblage patterns is a typical right oblique "seagull-type". Because Al-A2 type granite discrimination diagram shows the A2-type characteristics of typical aluminous A-type granites , it means that the A-type granites are likely to be products of tonalite-granodioritic magma through fractional crystallization, and the tonalite-granodioritic magma is formed by young earth crust (oceanic crust and island arc) through partly melting. The conditions of large-scale mineralization are mature.%西准噶尔地区广泛发育晚古生代后碰撞花岗岩,年龄多集中于300Ma左右,在时代上属于晚石炭世,A型花岗岩具有具有高硅、低铝、富碱、准铝质-弱过铝质、贫钙、低镁,10000×Ga/Al比值较大,强烈富集高场强元素(HFSE)及Zr、Y、Ga等元素,Sr、Ba强烈亏损,稀土配分模式图呈现典型的右倾“海鸥型”等,并且在A1—A2型花岗岩判别图解显示具有典型的铝质A型的A2型花岗岩特征,表明A型花岗岩可能是年轻地壳(洋壳和岛弧)部分熔融形成的美云闪长-花岗闪长岩质岩浆经进一步分离结晶作用的产物,具备规模成矿的条件.
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