2480 Ma OLD ZIRCONS FROM GRANULITE FACIES ROCKS FROM EAST HEBEI PROVINCE, NORTH CHINA

• 作 者: R.T.PIDGEON
• 出 处: 地质论评
• 发表日期: 1980年03期
• 关键词: zircon facies EAST populations isotopic slightly have 麻粒岩相 同位素年龄 abundant

U-Pb isotopic age determinations are reported for zircon fractions from a tonalite gneiss from Kuo Tsia Kou and a retrogressed two-pyroxene granulite from Taipingzhai in the East Hopei Province of North China. Although the zircon U-Pb systems are slightly discordant the linear distribution of Pb/U points on a concordia plot indicates that zircon populations from both rocks have an age of 2480±20 Ma.This is interpreted as the age of the granulite facies metamorphism which affected the Archaean rocks of East Hopei Province.

U-Pb isotopic age determinations are reported for zircon fractions from a tonalite gneiss from Kuo Tsia Kou and a retrogressed two-pyroxene granulite from Taipingzhai in the East Hopei Province of North China. Although the zircon U-Pb systems are slightly discordant the linear distribution of Pb / U points on a concordia plot indicates that zircon populations from both rocks have an age of 2480 ± 20 Ma. This is interpreted as the age of the granite facies metamorphism which affected the Archaean rocks of East Hopei Province.