Eolian Deposits in the Middle Reaches of the Yangtze River During Late Interstadial of the Last Glacial (4022KaBP) and Its Environmental Significance

Key words: 
• The middle reaches of Yangtze River /
• the interstadial of the Last Glacial /
• the yellowgrey soilsilt deposits layer /
• regional dustfall /
• local dust storm events

Abstract: The bottom yellowgrey soilsilt deposits layer at Dingshan sand dune profile originated from the regional dustfall accumulation in the late interstadial of the Last Glacial( 4022 ka BP). Thus the yellowgrey soilsilt had the same origin but had different facis deposits, grain combination are the same and have not characteristic differences; All curves of frequency have character of two apices, the first apex is main and cell value is 832 μm, the second apex is subordinate and cell value is 250500 μm. Cell value of 9.75±0.25Φ~4.25±0.25Φ(1~62.5 μm) have the similar linear change at vertical and compose the first kurtosis, the content changes at different grain vertical is sensitive index on strong and weak changes of winter monsoon; 2.25±0.25Φ~-0.75±0.25Φ (180~2000 μm) have the similar linear change and compose the second kurtosis, the content changes at different grain profiles indicate dry and wet situation at the circumstance of the winter climate and regional dust storm events. At the weak stage of regional dustfall accumulation it had strongly regional dust storm events, indicating that it was dry at local places in the winter.