State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, Hubei, China;2. Faculty of Earth Sciences, China University of Geosciences (Wuhan) , Wuhan 430074, Hubei, China;3. Xi'an Center of Geological Survey, China Geological Survey, Xi`an 710054, Shaanxi, China;4. Wuhan Center of Geological Survey, China Geological Survey, Wuhan 430205, Hubei, China
Based on the data obtained from 1:250 000 geological mapping conducted by CGS during 1996-2008 and the previous studies of Oligocene strata, the authors investigated the evolution of the Oligocene tectonic lithofacies paleogeography in the Tibetan Plateau. The paleogeographic configuration remained high in elevation on the eastern side and low in the western side; depressed basins were distributed in Tarim, Qaidam, Qiangtang, Hoh Xil and Chengdu; uplifted and erosional areas lay in Gangdisê, Himalayan and Karakorum; and the paleo-Yarlung Zangbo River flowed from eastern Nang County to western Khalatse. The evolution characteristics of the Oligocene tectonic-lithofacies paleogeography responded to the tectonic uplift of the Tibetan Plateau, with two strong uplift stages existent during 34-30Ma (Stage A) and 25-23Ma (Stage B).