Hf. Zhang et al., U-Pb zircon age of the foliated garnet-bearing granites in western Dabie Mountains, Central China, CHIN SCI B, 46(19), 2001, pp. 1657-1660
U-Pb zircon dating on two foliated garnet-bearing granite samples in the we
stern Dabie ultrahigh-pressure (UHP) metamorphic unit yields concordant age
s of (234 +/- 4) Ma and (227 +/- 5) Ma, respectively. These ages, following
the UHP peak metamorphism, represent the magma emplacement ages for the fo
liated garnet-bearing granites. This, for the first time, shows that there
are the Triassic granites in the Dabie Mountains. The foliated garnet-beari
ng granites resemble A-type granite in geochemical characteristics, indicat
ing that they were formed in extensional geodynamic setting. The magma form
ation reflects a reheating event in the Dabie orogenic belt and it enhances
the transfer of tectonic regime from collision into extension and promotes
the rapid exhumation into lower crust for the UHP metamorphic rocks.