GEOMORPHOLOGICAL STUDIES ON THE LATE PLEISTOCENE GLACIATION IN THE HIGH MOUNTAINS OF TAIWAN

The high mountain ranges of Taiwan are unglaciated at present, but investigations based on field work and air photo study in Nanhuta Shan (3742 m), Hsueh Shan (3884 m) and Yu Shan (3995 m) show a remarkably extensive Late Pleistocene glaciation and a deeper ELA depression in these areas than reported before [1]. Various glacial landforms and deposits have been mapped, e.g. U-shaped valleys, glacial trimlines, roches moutonnées, moraines and erratic boulders. Landforms were analysed by size, geometry, location and composition. Sediment analyses include lithology, grain size, grain morphology and sediment fabric. A small icecap with valley outlet glaciers and a thickness of about 150 m during the maximum stage was reconstructed for the Nanhuta Shan massif [2]. Glacial deposits were found down to 2200 m in the Nanhu Valley. Glacial deposits have been sampled for OSL and rock surface exposure dating, which were applied in the Taiwanese mountains for the first time. The data show a maximum extent of the glaciation during the MIS 4. The ELA depression was 1100 m. Further data were obtained for the Late Glacial/ Early Holocene period, when the ELA was depressed by about 500 m. All ages are consistent with each other and with the geomorphological data in the study areas. The dose rates of the sediments and the bleaching of the grains in glacial environments seem to be sufficient for dating by OSL.

1. Cui, Z., Yang, Ch., Liu, G., Zhang, W., Wang, S. & Sung, Qu., 2002. The Quaternary glaciation of Shesan Mountain in Taiwan and glacial classification in monsoon areas. Quaternary International, 97-98: pp. 147-153. 2. Hebenstreit, R. & Boese, M., 2003. Geomorphological evidence for a Late Pleistocene glaciation in the high mountains of Taiwan dated with age estimates by optically stimulated luminescence (OSL). Zeitschrift für Geomorphologie, N. F., Suppl.-Bd.130: pp. 31-49.