SHRIMP Dating and Recrystallization of Metamorphic Zircons from a Granitic Gneiss in the Sulu UHP Terrane

作     者：LI HongyanInstitute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037 Geosciences Rennes, Universite de Rennes 1, 35042 Rennes Cedex, France 

作者机构：Chinese Acad Geol Sci Inst Mineral Resources Beijing 100037 Peoples R China Univ Rennes 1 Geosci Rennes F-35042 Rennes France 

出 版 物：《Acta Geologica Sinica(English Edition)》 (地质学报（英文版）)

年 卷 期：2004年第78卷第1期

页      面：146-154页

核心收录：

学科分类：070902[理学-地球化学] 0709[理学-地质学] 07[理学] 0708[理学-地球物理学] 

基　　金：the National Natural Science Foundation of China(No.40399142 , No.40372037) Centre National de la Recherche Scientifique(CNRS)of France 

主　　题：recrystallization of zkcon metamorphic fluid SHRIMP dating granitic gneiss Qinglongshan Sulu China 

摘      要：An unusual zircon SHRIMP dating result of a granitic gneiss from the Qinglongshan eclogite-gneiss roadcut section is presented in this paper. The very peculiar and complicated internal structures, as well as the very low Th/U ratios (0.01-0.08) of the zircons indicate that they were formed by metamorphic recrystallization. Strongly in contrast with previously published zircon U-Pb ages of the Dabie-Sulu UHP metamorphic rocks where protolith ages of 600-800 Ma are commonly recorded, only metamorphic age of 218±5 Ma, defined by 18 analytical spots either in rim or in core of zircons, are recorded in this granitic gneiss. This age represents the time of the complete metamorphic recrystallization overprint on primary magmatic zircons. The recrystallization was derived by the UHP metamorphism, and was strengthened by the early stage of retrograde metamorphic fluid activity.