Magneticsusceptibility characteristics and environmental significance of the last glacial sandstorm deposition in Houtian sandy land in Nanchang City
Objectives:A series of sand hills formed under specific climatic conditions are widely distributed around the Poyang Lake and the lower reaches of the Ganjiang River.Aeolian sand deposits are non-zonal deposits in the subtropical region of southern China.The authors carried out many investigations on the coast of Poyang Lake in the subtropical humid monsoon climate zone,and took the aeolian sand deposition profile of Houtian Sandy Land as the research object to explore the significance of magnetic susceptibility to paleoclimate and the climate change process of the last glacial period in Houtian Sandy Land.Methods:This study carried out Optically Stimulated Luminescence (OSL) dating method,magnetic susceptibility,grain size and heavy mineral analysis of paleoaeolian sand landforms in the Houtian section of southern Poyang Lake.Results:The results of magnetic susceptibility,grain size and heavy mineral characteristics indicate that the formation environment of different sedimentary facies is different.The dune sand layer in the profile has generally low magnetic susceptibility,coarser mean grain size (Mz),lower maturity index (ZTR),and higher weathering index (HW),suggesting low weathering degree under strong winter monsoon,dry,and cold climatic conditions.On the other hand,the sandy paleosol layer exhibits higher magnetic susceptibility,finer Mz,higher ZTR index,and lower HW index,indicating lower weathering degree formed in a warm and humid climate environment with weak winter monsoon and strong summer monsoon.Additionally,the Ⅰ (77.0～57.1 ka),Ⅲ (49.7～36.8 ka),and Ⅴ (29.7～14.9 ka) stages of the Houtian section correspond to the MIS4,MIS3 b,and MIS2 stages of deep-sea oxygen isotopes,respectively,signifying a cold period,strong winter monsoon,and low magnetic susceptibility.The Ⅱ (57.1～49.7 ka) and Ⅳ (36.8～29.7 ka) stages correspond to the MIS3c and MIS3a stages,respectively,indicating a warm period with strong summer monsoon and high magnetic susceptibility.Conclusions:The climate change features contrast sharply with the record of magnetic susceptibility and mean grain size of the Weinan section on the Loess Plateau,deep-sea oxygen isotope stage and δ18O records of Chinese subtropical cave stalagmites.It can be seen that magnetic susceptibility can also effectively reveal climate change in southern aeolian sand landforms.
万方数据
维普
