Study On The Restoration Of Cenozoic Prototypes Of Qaidam Basin

The Qaidam basin, with an average elevation of～2500m, is the largest petroliferous sedimentary basin in northeastern Tibetan Plateau, and surrounded by Altyn Tagh to the northwest, South Qilian Shan to the northeast and Eastern Kunlun Shan to the south. It's also an important place recording the formation and evolution of the Tibetan Plateau. Research on its Cenozoic Prototypes will provide a new constraint for study on the uplift of Tibetan Plateau.In this dissertation, we restored Cenozoic Prototypes of the Qaidam basin during various periods, based on analysis of the tectonic settings, original facies and thickness of sedimentary rocks, restoration of balanced cross-sections and related well data.The original sedimentary ranges of various periods are different from that of the present and much bigger in Qaidam basin, probably resulting from the compressive stress induced by Cenozoic India-Tibetan collision. The southern part of Qaidam basin experienced mainly two stages of tectonic deformations at the end of depositing period of Xiaganchaigou formation (late Eocene -Oligocene) and after the depositing period of Shizigou formation (since Middle Pliocene) respectively, due to the uplift of Altyn Tagh and northward compression of Eastern Kunlun Shan. However, tectonic deformation of the northern part of the basin mainly occurred during the depositing period of Shizigou formation and the Qarternary (since Late Miocene) owing to the uplift of South Qilian Shan.Qaidam Basin experienced two different evolutional processes during the Cenozoic: a depression during Paleocene-Eocene time (depositing period of Lulehe formation and Xiaganchaigou formation), and a compressional depression altered by strike-slip thrust since the Oligocene time. And the subsiding center of Qaidam basin transferred eastward over time. Finally, the dissertation also discussed the geodynamic model for the Cenozoic evolution.