Aeolian sediments evolution controlled by fluvial processes, climate change and human activities since LGM in the Qaidam Basin, Qinghai-Tibetan Plateau

摘要

Aeolian sediments are widely distributed in the eastern Qaidam Basin (QB), the main habitats for human in the hyper-arid basin during the Holocene, especially since 3 ka. The evolution of aeolian sediments is an important factor for the environmental change, and influence human activities and migration. However, many questions, e.g., when the aeolian sediments start to accumulate, what controls their initiation and how their evolution responds to climate change and human activities, still need further studies. In this study, we present a detailed Optically Stimulated Luminescence (OSL) chronology for both aeolian and underlying fluvial sediments from the Tiekui Desert in the eastern QB to discuss aeolian and fluvial processes, climatic changes, desert evolution, and human activities. Dating results show that: (1) underlying fluvial sediments were formed during similar to 23.9-12.1 ka, and the erosion caused by the fluvial process may provide an explanation for the absence of aeolian sediments during and before this period; (2) aeolian sediments accumulated from ca. 9-8 ka to modern times, with loess development from 9-8 ka to 1.6 ka and 1.4-0.7 ka, and dune sand accumulation at 1.6-1.4 ka and 0.7-0 ka. Through the comparison with the local and global palaeoclimatic records, we suggest that desert evolution in this region was sensitive to climatic changes induced by the Asian summer monsoon. Detailed local historical records of the past 2000 years suggest that desert evolution was also influenced by human activities. (C) 2014 Elsevier Ltd and INQUA. All rights reserved.