Pollen,Susceptibility And Grading Analysis Of Hutouliang Profile Respond To Environment Changes In Nihewan

This paper presents the results of pollen,grading and magnetic susceptibility analyses carried out on material from Hutouliang profile of Nihewan Basin and supported by optical stimulated luminescence dating.A reconstruction of the late middle Pleistocene shows that the tree pollen type mainly includes Abies,Picea,Pinus,Larix,Quercus,Betula,Ulmus,Acer,Carpinus;shrub pollen type mainly includes Juglans,Ephedraceae,Nitraria,Elaeagnaceae,Verbenaceae;common herb pollen type mainly includes Artemisia,Compositae,Chennopodiaceae,Gramineae,Ranunculaceae,Cyperaceae,Thalictrum,Typhaceae,Polygonaceae.Fern spores mainly have Pediastraceae,Monolete spore,Polypodiaceae,Trilete spore,Selaginella.According to the pollen percentages,the profile was divided into 4 pollen zones.Within the period of 176.4~176.3ka B.P.,pollen assemblages show that the study area’s vegetation landscape was occupied by wooded steppe composed of Pinus,Picea,Abies these dark coniferous.Within the period of 176.3~169.0ka B.P.,the landscape change to grassland drought,the herb vegetation dominated by Artemisia,Chenopodiaceae and Compositae,it suggests the climate was cold and dry.Within the period of 169.0~157.3ka B.P.,the forest steppe landscape was composed of broad-leaf species such as deciduous Larix,Betula,Quercus,Tilia,Acer and so on.It suggests,comparing to the last stage,there is warm and wet climate situation during this period.Within the period of 157.3 ~ 143.8ka B.P.,the landscape was similar with the first stage occupied by forest steppe composed of Picea,Abies and Pinus again.It suggests that the climate during this period was back to cold and wet.The result of grading and Magnetic susceptibility analyses show that between 143.8ka B.P.and 176.4ka B.P.,when the climate was dry,the lake’s water level dropped,then the diluvial deposit from piedmont flooded into the lake,it corresponded to the percentage of coarse particle increasing,the curve of magnetic susceptibility reach to the highest top;when the climate was wet,water level of the lake started to rise,lake expansion,corresponding to the percentage of fine particle increased,the curve of magnetic susceptibility reach to the lowest.The grading and Magnetic susceptibilityanalyses results of Hutouliang profile respond to environment and climate changes well in Nihewan.