Geomorphologic Structure, Characteristics and Processes in the Cangshan Mountains: Explanations for the Formation and Development of the Dali Glaciation

摘要

The area around Cangshan Mountain, located on the southeastern fringes of the Tibetan Plateau, is a key region in terms of revealing the processes involved in the uplifting of the Tibetan Plateau, plus its environmental effects. Based on systemic field and laboratory work, this study uncovers the step-like geomorphologic structure, characteristics and processes revealed in the Cangshan Mountain area, to argue for the formation and development of the Quaternary glaciation there. The results indicate that there were two paleo-glaciations in the area, which were the early and late Dali Glaciations, and that these occurred during the time periods 5.76 × 104 aBP and 1.6 × 104 aBP respectively, being the southernmost paleo-glaciations to have taken place in China. Two step-like paleo-planation surfaces were formed vertically at the mountain (that is, at the summit of Cangshan, which is 3800 to 4000 m above sea level (a.s.l) in height;and at the paleo-glacial and peri-glacial active zones: 3700 to 3900 m a.s.l. in height). Meanwhile three widespread erosion surfaces can be identified at about 2900 to 3500 m, 3000 to 3100 m and 2450 to 2550 m a.s.l. in height;three fluvial fans developed on the landform at about 2250 to 2200 m, 2200 to 2150 m and 2150 to 2100 m a.s.l. in height respectively, and lacustrine relief developed surrounding the Erhai Lake.