Evidence for palaeo-Tethyan oceanic subduction within central Qiangtang, northern Tibet

► Phase equilibria modeling of garnet blueschist within Rongma area, northern Tibet. ► Mineral phase transition taking place at high oxygen contents. ► Deep subduction of oceanic crust between southern and northern Qiangtang blocks. ► Blueschist belt defines location of palaeo-Tethyan suture zone at northern Tibet.