Climate and environmental changes recorded by aeolian sediment during the last glaciation in the western Qaidam Basin

Abstract

Aeolian sediments are widely distributed in the Qaidam Basin (QB) on the northeastern Qinghai-Tibet Plateau (QTP) and are ideal carriers of information for studying the environmental evolution of the basin. However, due to factors such as dry denudation and glacier erosion, there is a lack of palaeo-aeolian sediment records in the late glacial period. This study applied quartz optically stimulated luminescence (OSL) dating to fluvial-aeolian sequences in the TLH profile, which were exposed by river downcutting in the Tora River. In addition, OSL ages were combined with grain size and chemical elements to explore the sedimentary and environmental changes in the late glacial period recorded by palaeo-aeolian sediments in the QB. The results show that aeolian sediment accumulated earlier than the last glacial period in the QB and that the QB experienced multiple alternations of drying and wetting during this period. From approximately 70.45 ka BP to 60.87 ka BP, thick aeolian sediment with noticeable cross-bedding developed in this location, suggesting relatively dry environmental conditions and intense sand activities. From 60.87 ka BP to 58.56 ka BP, the environmental proxies revealed two distinct layers of fluvial deposits, with relatively coarse average grain sizes and weak chemical weathering, indicating wetter conditions. This region experienced alternations of drying and wetting between 58.56 ka BP and 41.09 ka BP, resulting in an aeolian sand layer and a freeze-thaw folded layer. This research is a good supporter of climate and environmental changes in the last glaciation.