Geological mapping at a scale of 1:250000 coupled with related researches in recent years reveal well Early Cenozoic paleo-tectonic evolution of the Tibetan Plateau.Marine deposits and foraminifera assemblages indicate that the Tethys-Himalaya Ocean and the Southwest Tarim Sea existed in the south and north of the Tibetan Plateau,respectively,in Paleocene-Eocene.The paleo oceanic plate between the Indian continental plate and the Lhasa block had been as wide as 900km at beginning of the Cenozoic Era.Late Paleocene transgressions of the paleo-sea led to the formation of paleo-bays in the southern Lhasa block.Northward subduction of the Tethys-Himalaya Oceanic Plate caused magma emplacement and volcanic eruptions of the Linzizong Group in 64.5-44.3 Ma,which formed the Paleocene-Eocene Gangdise Magmatic Arc in the north of Yalung-Zangbu Suture(YZS),accompanied by intensive thrust in the Lhasa,Qiangtang,Hoh Xil and Kunlun blocks.The Paleocene Eocene depression of basins reached to a depth of 3500-4800 m along major thrust faults and 680-850 m along the boundary normal faults in central Tibetan Plateau,and the Paleocene-Eocene depression of the Tarim and Qaidam basins without evident contractions were only as deep as 300-580 m and 600-830 m,respectively,far away from central Tibetan Plateau.Low elevation plains formed in the southern continental margin of the Tethy-Himalaya Ocean,the central Tibet and the Tarim basin in Paleocene-Early Eocene.The Tibetan Plateau and Himalaya Mts.mainly uplifted after the Indian Eurasian continental collision in Early-Middle Eocene.