摘要
///The Tongbai orogen is situated at the junction between the Qinling and Dabie-Sulu orogenes. The Tongbai high-pressure (HP) metamorphic terrane comprises two HP slices (I and II) and a tectonic mélange zone in the north and a blueschist-greenschist zone in the south. U-Pb, Lu-Hf, Rb-Sr and Ar-Ar multichronometric data indicate the peak metamorphism of the HP slice I taking place at 255 Ma, whereas cooling to the closure temperature of muscovite at 238 Ma. By contrast, the metamorphic ages of the HP slice II are as young as 232~220 Ma, whereas gneissic granites dominating the Tongbai complex were emplaced at 140 Ma. Based on the similarity between the Tongbai and North Dabie complexes, the authors consider that a lower P-T environment and the absence of UHP rocks in the Tongbai HP metamorphic terrane might be resulted from the shallower subduction of the South China block towards the west. The final west-narrowing architecture of the Tongbai-Dabie HP/UHP metamorphic belt is related to the Early Cretaceous extrusion towards the east.