Seminar

It is generally believed that extrusion of SE Tibet was bounded by the dextral Gaoligong and the sinistral Ailaoshan-Red River strike-slip shear zones from the Oligocene to early Miocene. This study integrates field mapping, structural analysis and geochronology in western Yunnan Province, where foliated Precambrian basement rocks and Late Cretaceous to early Eocene plutons are exposed to the west of the Gaoligong shear zone. We found that four late Eocene-early Miocene gneiss domes are bounded by coeval detachments and strike-slip shear zones. Detachments caused mid-crustal decoupling and fast SW-ward extrusion of deep rocks, whereas parallel dextral strike-slip shear zones controlled extrusion and clockwise rotation. We propose a lithospheric bending model around the Indian indenter since late Eocene.