Geochemistry of the Carboniferous-Permian post-collisional granitic rocks from Tianshan

The geochemical study of Carboniferous-Permian post-collisional granitic rocks from different tectonic units in Tianshan reveals that they belong to high-Kcalc-alkalic or shohonitic series and are dominated by calc-alkalic granitic rocks.Compared to granitic rocks developed within or along the margin of paleo-microplate,the Carboniferous-Permian granitic rocks developing in rift setting are rich in MgO,TiO₂ and Na₂O and poor in K₂O,Nb,Th,indicating they are derived from different sources,maybe the former dominantly derived from the mantle and crust mixture sources and the latter mainly from the crust sources.The granitic rocks occurred on same tectonic units but in different sites also are different in geochemistry.For example,those from Temuer summit in the westernend of Yili microplate have higher Fe,Mg,K,Nb,Thand lower Zr,Ba than those from Kuluket age microplate in the middle-eastern stage of Tianshan mountains,which shows the difference of the basement in eastern and western Tianshan mountains.