SEDIMENTARY FEATURES OF THE CENOZOIC IN THE WESTERN QAIDAM BASIN:RESPONSE TO STRIKE-SLIPPING OF THE ALTUN FAULT
Liu Zuhan1, Wu Genyao2, Yang Mengda1, Guo Zeqing3, Wen Zhifeng3
1. Institute of Geology, Hunan University of Science and Technology, Xiangtan, Hunan 411201; 2. Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029; 3. College of Earth Resources and Information, University of Petroleum, Dongying, Shandong 257061
The development of the Qaidam Basin in Cenozoic was coupled with two orogenic processes:the Neotethyan orogenics (the Kumlun mountain chains) and the shear-orogenics of the Altun fault. In the western part of Qaidam, the Altun fault played a more important role in the basin development. Based on a systematic description of the Cenozoic strata, an analysis of the carbonate-argillaceous rocks in the Xiayoushashan Formation and a comparison with the neighboring North Xorkol Basin, the following knowledges could be drawn. 1)The Altun fault was a dextral strike-slip fault in Paleogene, and become a sinistral one from Miocene. Correspondingly, the related thrusting of early generation (the latest Cretaceous-Eocene) in the northern margin of the basin expanded towards the northeast, and the thrusting of later generation (Pliocene-Pleistocene) expanded towards the southwest. 2)The oblique-thrusting occurred in Eocene and Pliocene respectively, which resulted in a high sedimentary ratio of the Upper Member of Xiaganchaigou Formation and the Shizigou Formation, and the sedimentary centers immigrating eastwards obviously during that time. 3)The Miocene might be a relaxation period of the Altun fault owing to collapse of the Neotethysides. Co-operated with the NE-striking normal faults, a pull-apart basin might be occurred in western Qaidam where the sediments were dominated by the carbonate-argillaceous rocks, obviously different from the sediments in the neighboring North Xorkol Basin. 4)The Altun fault experienced an intracontinental cycle of extension-compression during Neogene in a background of sinistral strike-slipping.
Liu Zuhan,Wu Genyao,Yang Mengda et al. SEDIMENTARY FEATURES OF THE CENOZOIC IN THE WESTERN QAIDAM BASIN:RESPONSE TO STRIKE-SLIPPING OF THE ALTUN FAULT[J]. Chinese Journal of Geology, 2006, (2): 344-354.