TIMS U-Pb Isotopic Dating and Geochemical Characteristics of Paleozoic Granitic Rocks from the Middle-Western Section of Tianshan

The results of TIMS U-Pbisotopic dating for the Paleozoic granitic rocks from the middle-western section of Tianshan show that,the ages of four granitic rock bodies,plagiogranite,alkali feldspar granite,granodiorite and quartz diorite,intruded into Ordovician Kekenaike Group distributing between Tuokeshun and Kumishi,Central Tianshan,are 424.1±1.1 Ma,395.1±0.9 Ma,393.2±1.4 Ma and 327.3±0.9 Ma,respectively,which reveal three stages of structure-magma events in middle section of Central Tianshan,occurred in Early Silurian,Middle Devonian and Early Carbon iferous,respectively;the biotite granite from Hax legendaban,Central Tiang shan,formed in 286.8±0.8 Ma;the granodio rite from Guozigou,Huocheng County,granodiorite from Zhao shu coalmine,and bojite from Zheketai,Xinyuan County,all of which distribute in the Carbon iferous to Permian riftbelt of Yili,formed in 351.9±1.6Ma,348.4±0.8 Ma and 308.3±1.2 Ma,resp ectivel.The hornblende-plagiog ranite and biotite granitefrom the southern section of Du-ku Road,Kuergan,formed in 426.3±1.9 Ma and 425.1±1.8 Ma,respectively.