Late Quaternary glacial advances in the eastern Qilianshan, north-eastern Tibet, as inferred from luminescence dating of fluvioglacial sediments

ABSTRACT The Qilianshan [shan means ‘mountain(s)’ in Chinese] are important for understanding the Quaternary glaciations which occurred along the north‐eastern margins of the Tibetan Plateau (TP). Two sets of moraines identified in the Gangshika Valley on the southern slopes of the Qilianshan, and in the Jindonggou Valley on the northern slopes of the Lenglongling Ridge in the eastern Qilianshan, were dated using optically stimulated luminescence (OSL) dating. The De values of the sediments were determined using single aliquot regeneration (SAR) and ‘global standardized growth curve’ (gSGC) procedures. The gSGC method was first applied to glacial sediment and proved to be adaptable. Based on De distribution analysis, and a comparison between the ages of coarse‐grained (90–125 μm) quartz, we concluded that the minimum age model (MAM) OSL age obtained may be closer to the burial age of the sediments. The first set of moraines in the Gangshika Valley was formed at 18.1 ± 1.8 ka. The second set of moraines in both the Gangshika and the Jindonggou valleys was mainly formed at ∼12.5–10.7 ka, consistent with the Younger Drays chronozone, most probably covering the moraines produced at 14.3 ± 1.4 ka. These results indicate that the glaciers along the Lenglongling Ridge were sensitive to abrupt decreases in temperature.