The discovery of ~2.0 Ga metamorphosed granite in western Dabie Mountains and its Hf isotopic characteristics

Geochronological data of 2.10-1.90 Ga tectonic thermal events in the Yangtze block are widely documented, but the magmatic rocks of this period in the Dabie area have not been reported. On the basis of field geological survey, the geochronological and zircon Hf isotopes of the metamorphic granite from the Jinpan pluton in western Dabie Mountains were analyzed. U-Pb dating of magmatic zircons from the metamorphic granite yielded age of (2022±17)Ma (MSWD=2.3), which represents Paleoproterozoic magmatic event in the Dabie orogenic belt. The negative ε_Hf(t) values (-10.6--7.6) and T_DM2 ages (2.95-3.12 Ga) of zircons indicate that the Jinpan granite might be derived from the reconstruction of ancient continental crust. The previous Hf isotope results also indicate that the widely-distributed Archean continental crust (2.95-3.18 Ga) in the Yangtze Block provided material source for the magmatic evolution of the Jinpan metamorphic granite. The Jinpan pluton was formed in the period of Paleoproterozoic collisional orogeny (2.03-1.93 Ga), and it might be the response to the convergent of Columbia supercontinent. The identification of the~2.0 Ga granite provides a new evidence for the evolution of Precambrian tectonic-magmatic events in the Dabie orogenic belt.