Climatic Characteristics Changes Recorded By Eolian Deposition In The Houtian Desert Of Nanchang During The Last Glacial Period

The series of sedimentary sequences superimposed by dunes sand-paleosol is widely distributed in the southern part of Nanchang,Xinjian District.Based on the field investigation,we use optical stimulated luminescence dating,soil particle size and magnetic susceptibility which inverted the characteristics of the last glacial period and its relationship with the East Asian monsoon.Then we found the Houtian section mainly consists of the alternating deposition of 3 layers of dune sands and paleosol,and its top and bottom age is 14.9-77 ka BP,which is the product of the last glaciation.According to the analysis of the contents of grain size and OSL chronology,we got the conclusion as follows:1)The strata of the last glacial in the Houtian section can be divided into five stages,as HTS4(77-57.1ka BP),HTS3c(57.1-49.7ka BP),HTS3b(49.7-36.8ka BP),HTS3a(36.8-26.5ka BP),HTS2(26.5-14.9ka BP).2)The two results extracted by particle size-standard deviation method and principal component factor analysis showed that 12.619-20?m is positively correlated with Mean particle size and clay content,400-563.667?m is negatively correlated with Mean particle size and clay content,inspected that the indicator particle size of winter monsoon is400-563.667?m and the indicator particle size of summer monsoon is 12.619-20?m.3)The Mean particle size,clay content,susceptibility and sensitive particle size shows remarkable variations in alternation of peaks and valleys.The warm periods mainly correspond to strong summer monsoon indicated by stalagmite in Hulu Cave in China,as well as the peak of total amount of astronomical insolation at 65°N in July and susceptibility,which reveals that the sand-paleosol is developed in the warm period of HTS3 c,HTS3a and early HTS2.And cold periods mainly correspond to weak summer monsoon indicated by Guliya ice core in the West Kunlun Mountains,as well as the valley of total amount of astronomical insolation at 65°N in July,which reveals that the dunes sand is developed inthe cold period of HTS4,HTS3 b and late HTS2.The climate changes in the Houtian section during the Last Glacial period has a climate fluctuation of ten thousand years,which probably results from the mutual impact of total amount of insolation and East Asian monsoon.