SHRIMP zircon U-Pb dating in Jingshan "migmatitic granite", Bengbu and its geological significance

作     者：XU Wenliang, WANG Qinghai, YANG Debin, LIU Xiaochun & GUO Jinghui College of Earth Sciences, Jilin University, Changchun 130061, China Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081, China Institute of Geology & Geophysics, Chinese Academy of Sciences, Beijing 100029, China 

作者机构：College of Earth Sciences Jilin University Changchun China Institute of Geomechanics Chinese Academy of Geological Sciences Beijing China Institute of Geology & Geophysics Chinese Academy of Sciences Beijing China 

出 版 物：《Science China Earth Sciences》 (中国科学（地球科学英文版）)

年 卷 期：2005年第48卷第2期

页      面：185-191页

核心收录：

学科分类：070902[理学-地球化学] 0709[理学-地质学] 070901[理学-矿物学、岩石学、矿床学] 07[理学] 

基　　金：supported by MST(Grant No.TG1999075502) the National Natural Science Foundation of China(Grant No.40172030) Jilin University(Grant No.2002CX004) 

主　　题：zircon, U-Pb dating, migmatitic granite, geological significance, Bengbu. 

摘      要：The petrographic characteristics of Jingshan migmatitic granite and the occurrence of the magmatic zircons indicate that the granite was formed by normal crystallization of felsic melts. All zircons in the granite have inherited cores and fine-scale oscillatory zoning rims of magmatic origin. It is realized that the granite was formed at 160.2±1.3 Ma through dating magmatic zircons. The generation of the granitic magma could be related to the lithospheric mantle and/or lower crust delamination after the ultrahigh pressure metamorphism (UHPM) in Triassic. Most inherited zircons yield the ages of 217.1±6.6 Ma, which is consistent with the peak UHPM in the Dabie-Sulu orogenic belt. Some of the inherited zircons (433-722 Ma) constitute a discordia line with the upper intercept age of 850+85/-68 Ma and a lower intercept age of 261+100/-140 Ma. These ages imply that the granite could be derived from the partial melting of the crustal materials of the South China Block that was intensively superimposed by the UHPM. The UHPM could be the reason for the major Pb loss at ±220 Ma.