Terraces and Tectonic Uplifts at Yandantu and Changcaogou on the Northern Margin Fault of Altun

Terraces and Tectonic Uplifts at Yandantu and Changcaogou on the Northern Margin Fault of

Altun

Zheng Rongzhang;Xu Xiwei;Wang Feng;Li Jianping;Ji Fengju

【期刊名称】《中国地震研究（英文版）》 【年(卷),期】2004(018)004

【摘要】The formation of strath and strath terrace is closely related to tectonic uplift in the drainage basin. Based on the investigation of straths at Yandantu and Changcaogou on the eastern segment of the northern margin fault of Altun, and in combination with the paleoclimatic data,the tectonic uplift since late Epipleistocene as revealed by stream terraces at the two places is discussed.At Yandantu, three levels of stream terraces ( T1, T2 and T3 ) have developed since 16ka BP, where T1, T3 and T2 are fill terraces and the buried major straths are exposed. The ages of three treads are dated to be about 16. 1ka BP, 12.8ka BP and 6.2ka BP, respectively. The three terraces reflect three tectonic uplift events, while the ages of the treads represent the occurrence time of these events. The stream is still beveling the bedrock and widening the channel at present, and the modern strath is being generated. The uplift rate is 4.8 ～ 4.5mm/a since 16.1 ka BP in this area. From 12.8ka B.P to 6.2ka BP, The uplift rate was 6.4mm/a.The uplift rate is 3. 1mm/a since 6.2ka BP.At Changcaogou, four levels of stream