SHRIMP zircon U-Pb dating of the Gangou granitoids,Central Tianshan Mountains,Northwest China and tectonic significances

作     者：SHI YuRuo LIU DunYi ZHANG Qi JIAN Ping ZHANG FuQin MIAO LaiCheng 

作者机构：Beijing SHRIMP Center Institute of Geology Chinese Academy of Geological Sciences Beijing 100037 China Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China 

出 版 物：《Chinese Science Bulletin》 (CHINESE SCIENCE BULLETIN)

年 卷 期：2007年第52卷第11期

页      面：1507-1516页

核心收录：

学科分类：0710[理学-生物学] 07[理学] 071002[理学-动物学] 

基　　金：Supported by the National Natural Science Foundation of China (Grant Nos.40234045 and 40473030) 

主　　题：测定年龄 小虾 地域 天山 

摘      要：Two types of granitoids,highly deformed augen granitoids and undeformed fine-grained granitoids,are widely distributed in Gangou area,Central Tianshan Mountains,Northwest China. The augen granitoids are high-K calc-alkaline characterized by high K2O,Rb,Y and Th,and low Sr and Sr/Y. They also have high contents of large ion lithophile elements (LILE),such as Ba,Rb,K and Th,and relatively low con-tents of high field strength elements (HFSE),such as Zr,Y and Nb. The fine-grained granitoids are calc-alkaline characterized by high Sr,low Y and HREE,similar to adakitic rocks,and with Na2O/K2O2 (1.76―1.91),high ISr (0.70689―0.70981),and negative εNd(t ) (-2.4―-5.3). High-precision SHRIMP U-Pb zircon dating results indicate that the Gangou augen granitiods were formed at 428 ± 10 Ma,and the fine-grained granitoids were emplaced at 361―368 Ma. These geochemical and U-Pb zircon data have significant implications for the timing of closure of the Mishigou-Gangou Ocean and the evolution of the Central Tianshan orogenic belt.