A PRELIMINARY APPROACH TO THE ACTIVITY OF KUMUKOL ANTICLINE

Kumukol Basin,located at the north margin of the Tibetan plateau,is separated from the Qaidam Basin by the Qimantag Range geographically. It is the transitional region between the Tibetan plateau and Qaidam Basin,and also the leading edge of the growing main body of the plateau. Nowadays,East Kunlun Fault and Altyn Tagh Fault,two significant strike-slip faults of Tibetan plateau,as well as the compressional Qimantag folding thrust system,delimit the southern,western and northern borders of the basin,respectively. Therefore,the study on the tectonic deformation and tectonic evolution of the basin will play an important role in understanding the style and mechanism of the eastward expanding of Tibetan plateau.Although Kumukol Basin is delimited by strongly active strike-slip faults,a very large anticline is growing in the basin,with a similar strike of NWW-SEE to the Qimantag folding thrust system and the folds in Qaidam Basin,such as Youshashan fold,suggesting that the basin is compressional. In this study,the lateral growth of this anticline is revealed by the analysis on the topographic profiles and distribution of terraces. A conclusion,as well,is made that the large proluvial fan at the east segment of the anticline is a result of the glacier melt water based on the field survey and dating of terrace samples. According to the OSL and10Be exposure ages,the age of the fan is 87. 09±2. 31ka ~102. 4±3. 7ka,and accordingly,we can get a maximum uplift rate of(2. 78±0. 28)mm /a ~(3. 28±0. 28)mm /a for the anticline since late Pleistocene. Tectonically,Kumukol Basin is highly similar to Qaidam Basin on its north,both are strongly active and controlled by the regional NEE compression stress field of the Altyn Tagh Fault at its south.