The gabbros from the Leiwuqi area, eastern Tibet: Records of the Late Paleozoic break-up of the northern Gondwana

The Tibetan Plateau, which is located in the transitional zone of the Gondwana and Laurasia, plays a key role in studying the supercontinental convergence and cracking of Gondwana. As a result of the opening of the Tethys Oceans, the northern Gondwana started to rift during Late Paleozoic. Continental intraplate basaltic magmatism is typically considered to have been linked with continental break-up. Permian continental intraplate basaltic rocks have been recognized in the Tibetan Plateau and are considered as recording the Late Paleozoic rift of the northern Gondwana. However, these rocks mainly occur in the Qiangtang and Panjal Traps of western Tibetan Plateau, but no coeval basaltic rocks have been reported in eastern Tibetan Plateau. In this paper the authors present the results of the study of the Early Permian gabbros in the Leiwuqi area of eastern Tibetan Plateau. LA-ICP-MS zircon U-Pb dating reveals that the gabbros formed at 280±2Ma. The geochemical features of these gabbros are comparable with those of continental intraplate basalts (WPB). They exhibit positive values of zircon ε_Hf(t) (5.1~11.5), suggesting a depleted mantle origin. Taking into account previous data, the authors hold that these gabbros were related to the Early Permian Qiangtang-Panjal mantle plume. There-fore, Early Permian continental intraplate basaltic rocks developed in both western and eastern Tibetan Plateau and they were linked with the continental break-up of northern Gondwana and the opening of the Bangong Co-Nujiang Tethys ocean.