Major constituents and texture of the Tongbai-Dabie collisional orogenic belt

The present constitution and architecture of the Tongbai-Dabie orogenic belt is the combined result of the Triassic subduction collision, the extension tectonics postdating the HP-and UHP metamorphism, and thermo-tectonic evolutions in the Mesozoic-Cenozoic time. In addition to Yanshanian and post-Yanshanian magmatic intrusions, volcanics, and basin deposits, the lithotectonic constituents of the Dabie orogenic belt mainly consist of a core complex (CC) unit, a UHP unit, a HP unit, an epidote blueschist (EBS) unit and a sedimentary cover (SC) unit. Minor mafic-ultramafic plutons or massifs were intruded into or preserved within them. The rock slices of UHP, HP, and EBS units are progressively sandwiched between the underlying core complex and the overlying sedimentary cover. The distribution of lithotectonic units is controlled by an extensional tectonic framework postdated the collisional event. The tectonic pattern of the Tongbai-Dabie orogenic belt as a whole is similar to that of the metamorphic core complex described from the western North America, which is characterized by a general doming morphology with the development of multi-layered detachment zones.