Abstract

The Dabie–Sulu Orogen hosts the largest area of ultrahigh-pressure (UHP) rocks in the world. There is still significant divergence regarding the exhumation process and mechanism of UHP rocks in the Dabie Orogen, which mainly resulted from the erosion of large volumes of rocks in the Orogen during the post-collisional stage. Based on detailed field investigations, this study discovered the occurrence of E–W-trending sinistral shear belts that developed on the northeastern Dabie Orogen. These shear belts formed under greenschist facies conditions and are characterized by steep foliation and gentle mineral lineation. E–W-trending shear belts developed in HP rocks with metamorphic ages ranging from 227 to 219 Ma and were cut by the older phase of ductile shear belts of the Tan-Lu Fault Zone, indicating that they were formed around 219–197 Ma. Based on a comprehensive analysis of existing data, it can be concluded that E–W-trending shear belts were formed during the exhumation process of HP–UHP rocks. When HP rocks returned to the shallow crust and the lower UHP rocks continued to move, stress concentration occurred in the HP rocks and further resulted in the formation of E–W-trending shear belts. The development of E–W-trending shear belts indicates that HP–UHP rocks had essentially returned to the shallow crust by the Late Triassic, marking the near completion of the exhumation process.