Die jungpleistozäne Vergletscherung des Qinling Shan (Provinz Shaanxi).

Ein Beitrag zur Vergletscherungsproblematik ostchinesischer Gebirge

Abstract

Since the early investigations of LEE and v. WISSMANN, the question of Pleistocene glaciations in the mountains of East-China is strongly discussed. The central Qinling Shan (33°58 'N/107°45 'E) plays a key role by reconstructing the Pleistocene glaciations in the mountains of East-China. Recent geomorphological investigations prove the existence of late- Pleistocene glaciations in the Taibai Shan massif and lead to the hypothesis of a temporarily existing, small icecap with five minor outlet-glaciers around Ba Xian Tai (3767 m) and West-Po Ma Liang ridge (3450-3715 m). In the valleys around Ba Xian Tai several moraines exist above 2850 m a.s.l. Besides younger terminal moraines, representing stages of glacier retreat, the moraines were accumulated before 18,000 years B.P., as proved by two TL-datings. The lowest late-Pleistocene altitude of the glacier-snowline at 3250-3300 m a.s.l. is deduced from the lowest moraines. The resulting snowline depression was about 1000-1300 m, compared to the supposed present position. Remnants of older Pleistocene glaciations in other areas of Qinling Shan below 2600 m have not been observed. The morphological results from central Qinling Shan are compared with geomorphological findings in the neighbouring ranges Helan Shan (Inner Mongolia/Ningxia) and Minshan (Sichuan). The altitude of the late-Pleistocene snowline has increased from 3000-3100 m in the Helan Shan to 4000 m in the Minshan. Reports of Quaternary glaciations in mountain ranges below 2500 m a.s.l. in northeast China remain rather questionable.