Response of dune mobility and pedogenesis to fluctuations in monsoon precipitation and human activity in the Hulunbuir dune field, northeastern China, since the last deglaciation

摘要

The Hulunbuir dune field is located at the northern margin of the temperate monsoon zone in East Asia, and changes in dune activity and pedogenesis in the dune field are highly sensitive to the advance and retreat of the East Asian summer monsoon (EASM) and to human activity. Thus, the stratigraphic sequences of paleosol and aeolian sand of the dune field have great potential for reconstructing the history of dune activity and pedogenesis and their response to past fluctuations in monsoon precipitation and the intensity of human activity. However, our knowledge of the evolution of the landscape and paleoclimate of the dune field is limited. Here, we present the results of analyses of quartz optically stimulated luminescence (OSL), grain size and magnetic susceptibility (MS) from 13 representative sections in the Hulunbuir dune field. The grain-size analysis indicates that the sand layers are composed of typical aeolian sand, and the MS variations of the aeolian sand and sandy paleosol sequences mainly reflect changes in the intensity of pedogenesis. We combine our new OSL dating results with previously published OSL ages to refine the chronology of sand dune development. An OSL age hiatus in both aeolian sand and paleosol during the 5-7 ka indicates that aeolian deposition in Hulunbuir ceased almost completely during this period, which corresponds to the peak in EASM strength. Thus, our study provides new evidence for a delayed response of the EASM maximum to peak insolation forcing (11-10 ka) in the mid-latitude monsoon margin. In addition, we speculate that peaks in probability density (PD) from 1.2-0.7 ka and from 0.25-0 ka of aeolian sand accumulation correspond to population increases and the development of cultivation and animal husbandry in the Hulunbuir dune field.