A STUDY OF BASIN PROTOTYPE IN THE TERTIARY SYSTEM AND ITS DYNAMIC ANALYSIS IN THE NORTH MARGIN OF QAIDAM BASIN
XIE Jiubing1,3, ZHU Zhaoyu1,2, WANG Jincao1 and OUYANG Tingping1,2(1. CAS Key Laboratory of Marginal Sea Geology, Guangzhou Institute of Geochemistry, Chinese Academy of Science, Guangzhou, GD 510640, China; 2. State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Science, Xi′an, SX 710054, China; 3. Graduate School of the Chinese academy of sciences, Beijing 100049, China)
The Qaidam Basin, with its complicated evolution history, was regarded as a multiple basin in Tertiary by most researchers. In this paper, we have studied the basin evolution stages from the aspects of sedimentary tectonics and sedimentary phase. Our results indicate that the basin is comprised of three depressions with some sedimentary centers and is characterized by sinistral echelon during the Palaeogene. Thereafter the basin changes in general a wide trough with the strike NW-SE and is accompanied by some small depressions during the Neocene. Therefore, the authors consider that the basin was an asymmetrical strike-slip pull-apart basin in the Palaeogene but becomes a compressive depression basin in Neocene.