Zircon grains were analyzed by laser-ablation inductively coupled plasma–mass spectrometer at the China University of Geosciences (Wuhan) and at the Tianjin Institute of Geology and Mineral Resources, following the analytical procedures of each laboratory. All the zircon grains were measured using a laser spot diameter of 32 μm. The ages reported here are 206Pb/238U ages for zircons younger than 1000 Ma and 207Pb/206Pb ages for older grains. Individual zircon with <90% concordance was rejected.