新疆西天山查汗查哈花岗岩锆石U-Pb定年、岩石地球化学特征及其大地构造意义

查汗查哈岩体出露于新疆西天山东南段，位于中天山南缘断裂北缘的那拉提-中天山侵入岩带，岩性主要为片麻状花岗闪长岩和二长花岗岩。锆石U-Pb定年结果显示，查汗查哈岩体花岗质岩石形成于421.9±6.2 Ma。岩石地球化学特征表明其属于准铝质钙碱性Ⅰ型花岗岩，并具有较典型的大陆边缘弧侵入岩的特征。这一研究结果显示，南天山洋在晚志留世已经开始向北俯冲，并在中天山南缘形成大陆边缘弧环境。 

ZIRCON U-PB DATING AND GEOCHEMICAL FEATURES OF CHAHANCHAHA GRANITE FROM WESTERN TIANSHAN, XINJIANG: IMPLICATIONS FOR TECTONIC EVOLUTION

The Chahanchaha granitic body outcrops in the southeast part of the western Tianshan Mountains, Xinjiang, and it is located in the Nalati-Central Tianshan intrusive rock belt at the northern edge of the fault, south margin of the Central Tianshan. The rock type is dominated by granodiorite and monzonitic granite with weak gneissic foliation. The zircon U-Pb dating results indicate that the Chahanchaha granitic rocks formed at 421±6.2 Ma. The geochemical characteristics suggest that the granitic rocks are grouped in metaluminouscalc-alkaline I-type granite, which exhibits typical characteristics of intrusive rocks in the continental arc. These data demonstrate that the paleo-south Tianshan ocean crust has started northward subduction at late Silurian, resulting in a continental arc upon the overriding plate.