Tracing the sedimentary response to the rifting and opening of the Meso-Tethys Ocean

Knowledge of the rifting and opening process of the Meso-Tethys Ocean is important for understanding the evolution of the Tethys tectonic domain and for an in-depth understanding of Tethys dynamics. Sedimentary rocks are faithful recorders of surface expressions of tectonic events and are thus expected to have recorded the rifting and opening of the Meso-Tethys Ocean. This study presents petrography, sedimentology, zircon U-Pb geochronological data and Hf isotope data for the Carboniferous-Permian Shiquanhe stratigraphic succession in the Lhasa Terrane of the Tibetan Plateau. The data indicate that the 300 to 273 Ma Lagar and Angjie formations in the lower section of the Carboniferous-Permian Shiquanhe succession were deposited in the stable passive margin of northern Gondwana with sediment sources in Gondwanaland. However, the 273 to 252 Ma Xiala Formation in the upper section of the Carboniferous-Permian Shiquanhe succession was deposited in a tectonically active setting characterized by intense magmatic activity. Considering the transition from the Lagar and Angjie formations to the Xiala Formation, a significant change in depositional setting from tectonically stable to tectonically active occurred at ca 273 Ma. Similar Early-Middle Permian changes in depositional setting have also been identified in the South Qiangtang, Baoshan and Oman regions in the Tethyan tectonic domain. These widespread changes in depositional setting, together with Early-Middle Permian tectonic uplift and episodes of subsidence, as well as rift-related magmatism in the South Qiangtang, Baoshan, Himalayan, Zagros, Oman and Turkey regions once located in northern Gondwana, constitute a complete record of continental rifting-ocean opening associated with the diachronous opening of the Meso-Tethys Ocean during the Early-Middle Permian.