CHARACTERISTICS AND MECHANISMS OF AEOLIAN ACTIVITY IN THE DESERT BELT OF NORTHERN CHINA DURING THE LATE QUATERNARY WARM PERIODS BASED ON CLIMATE SIMULATION AND GEOLOGICAL RECORDS
The desert belt of northern China includes mainly four sandy lands(Maowusu,Hunshandake,Horqin,Hulunbeier)and eight sand seas(Taklamakan,Gurbantunggut,Kumtag,Chaidamu,Badain Jaran,Tengger,Wulanbuhe,Kubuqi),extending from 35°N to 50°N and from 75°E to 125°E.Therefore,studying the paleoenvironmental characteristics of the vast desert areas in northern China during warm periods(e.g.,MIS 5e and mid-Holocene)is essential for predicting and understanding the future scenarios of environments under global warming.However,due to the temporal discontinuity and spatial distribution gap of aeolian sand deposition,there are uncertainties in interpreting the paleoenvironmental characteristics of the desert belt in northern China during the MIS5e and the mid-Holocene.Here we used the paleoclimate models provided by the Coupled Model Intercomparison Project Phase 6(CMIP6)-the Paleoclimate Modeling Intercomparison Project Phase 4(PMIP4)to analyze the dune mobility index,aridity index and near-surface wind during the MIS5e and the mid-Holocene.Additionally,we combined probably robust age data from 125 published geological records(including lacustrine and alluvial sediments,aeolian-paleosol sequences)with paleoclimate simulations to reveal the characteristics and driving mechanisms of aeolian activity in the desert belt of northern China during the two warm periods studied herein.Our results show that:(1)As indicated by the decreased dune mobility index,aeolian activity weakened in the eastern and central portions of the desert belt in northern China during the MIS 5e and the mid-Holocene in contrast to the preindustrial period.However,a notable intensification of aeolian activity occurred in the western portion,especially during the MIS 5e.(2)The enhanced East Asian summer monsoon during warm periods resulted in increased precipitation in the eastern and central portion of the desert belt,improving surface moisture conditions,and thus suppressing aeolian activity.(3)Simultaneously,in the western portion,the westerly jet retreated northward leading to decreased precipitation,while rising temperatures caused increased meltwater to develop the fluvial-lacustrine deposits.Therefore,the increased dune mobility index occurred in the western portion,representing stronger aeolian activity during the warm periods compared with the preindustrial period.The deteriorated moisture conditions in the hinterland of western deserts and increased potential sand source from the fluvial-lacustrine sediments led to intensified aeolian activity in the western portion during warm periods.(4)During the MIS5e and the mid-Holocene,the near-surface wind decreased significantly in the desert belt compared with the piControl,which reduced the transport capacity and the probability of burying vegetation,providing important prerequisites for limiting aeolian processes.
arid and simi-arid zoneMIS5emid-HoloceneCMIP6-PMIP4 modelsdune mobility index
万方数据
维普
