Abstract:The northern Dabie ultrahigh pressure (UHP) metamorphic belt is one of the key regions to investigate the evolution of the basements of the Qinling-Dabie-Sulu orogenic belt. Migmatites are widely distributed in the northern Dabie belt. They have long been regarded as being formed at Mesozoic based on previous geochronological studies. Here we report zircon U-Pb ages and Hf isotopic compositions for migmatites at the Tuanfeng area in the northern Dabie belt. CL images reveal the zircons can be divided into two groups. The first magmatic zircons yield an upper intercept age of 2850±86 Ma, dating magma emplacement of protolith. The remaining zircons are metamorphic zircons. They gave a weighted mean 207Pb/206Pb age of 2011±12 Ma, which is interpreted as the age of migmatization. Most magmatic zircons have negative eHf(t) values (-8.1~2.2), corresponding to two-stage Hf isotopic model ages (TDM2) of 3.6-3.0 Ga, indicating that the protoliths might be formed by remelting of Paleoarchean crustal rocks in the Dabie orogen, with involvement of minor mantle-derived melts. By contrast, metamorphic zircons have positive eHf(t) values (0.3~8.2), corresponding to TDM2 of 2.7-2.2 Ga, revealing an open of Lu-Hf isotopic system during the Paleoproterozoic migmatization. Our study suggest a record of Paleoproterozoic migmatization during the assembly of the Columbia supercontinent, except for the Mesozoic migmatization. The protoliths of the Tuanfeng migmatites were formed in Neoarchean, with their TDM2 ages up to 3.6 Ga. It is thus inferred that the Archean basement might be widely distributed in the Dabie orogen.