Quaternary glacial deposition and glacial advance and retreat in the Zanda basin and its surrounding mountains in Ngari, Tibet

Abstract：Quaternary glacial deposits of the Zanda basin and its surrounding mountains may be divided in space distribution into：① glacial deposits in U-shape valleys and foothills in the basin and its surrounding mountains, ② glacial deposits in deep-incised valleys around the basin, ③ glacial deposits on the basin surface, ④ glacial deposits on high terraces of river valleys and in gullies of the basin, and ⑤ glacial deposits in piedmont zones of mountains around the basin. Glacial deposits in different areas differ markedly with respect to the gravel composition, roundness, textures and structures, geomorphologic features. The Quaternary glacial development in the region may be divided from early to late times into the periglacial stage, glacial advance stage, biggest glacial stage and glacial retreat stage according to the features and distribution of glacial deposits. The glacial types corresponding to these stages are the valley, piedmont and ice-cap glacier development stage, ice field glacier development stage and ice-cap, valley glacier and piedmont glacier development stage. The existing data indicate that the Zanda basin and its surrounding mountains are areas where the most abundant, complete and continuously occurring and best-preserved Quaternary glacial deposits are found on the Qinghai-Tibet Plateau. This research provides valuable basic data for the study of Quaternary glaciers in this region and the Qinghai-Tibet Plateau, division and correlation of glacial epochs, establishment of climatostratigraphy and climatic and paleoenvironmental studies.