Timing of the granulite facies metamorphism in the Sanggan area, North China craton: zircon U-Pb geochronology

Zircon U-Pb ages are reported for three samples of intrusive rocks in Khondalite series in the Sanggan area, North China craton. The age of meta-granite is dated as 2005 +/- 9 Ma, implying that the sedimentary sequences in Khondalites series formed before 2.0Ga. The age of 1921 +/- 1 Ma for the meta-diorite constrain the age of granulite facies metamorphism younger than this date. The age of 1892 +/- 10 Ma for garnet granite is obtained, but the granite crystallization age seems a little younger than the date considering the morphology of zircons. On the basis of these dates and of a concise review of previous age data, it is inferred that the Khondalite series was subjected to granulite facies metamorphism at about 1.87Ga together with tonalitic granulites and HP basic granulites in the Sanggan area.