| The surrounding area of Poyang Lake is located in the subtropical zone and north subtropical zone at the junction, the sensitive area special geographical position and unique terrain to make it become the Quaternary environmental changes. This paper selects Jiangxi Poyang Lake surrounding area as the study area, the area with different types of aeolian sediments as the research carrier, carry out field investigation in "Y" shape of area of annulus Poyang Lake West-South-East, choice of aeolian sand, aggradation Quaternary red earth, yellow brown soil and aeolian deposits of typical section22,226samples were collected, the collection of sediment samples and the grain size, magnetic susceptibility test, and combined with the area during the last glacial period, when the wind conditions and distribution characteristics of all kinds of sediments, and compare their similarities and differences in grain size parameters, particle size composition, from space on the different types of wind into law and the relationship between sediments. The main conclusions are as follows:(1) Poyang Lake surrounding areas of different types of eolian deposits in Quaternary sediments in the distribution characteristics and the section structure shows aeolian characteristics, there are differences in the size composition and grain size parameters. HGSC, XXZC, LJD, HG etc. Aeolian Sand profile size display, sand (>63μm) was the dominant grain size, mean content between39.71%～66.04%, silt (4～63μm) were the second, the mean content between25.81%～46.58%, clay (<4μm) minimum, average between8.15%～25.64%of near source material; accumulation during the strong storm conditions; SJL, LSDM, CJZ, HTG, yellow brown soil profile size that silt (4～63μm) advantage of grain size, the average content is between59.07%～74.05%, followed by clay (<4μm) grain size, content is between24.32%-34.75%, the sand content of at least, between1.64%-8.67%; XZX, SJP, JX1, YX, aeolian laterite profile size composition in silty sand (4～63μm) was the dominant grain size, average content is between42.55%-68.19%, followed by clay (<4μm) grain size, content is between26.54%～39.36%, the sand content of at least, between0.43%and4.03%. In contrast, the grain size composition more similar. Aeolian sand degree significantly thicker in the yellow brown soil and aeolian red clay. Further comparison, aeolian sand in <63μm part of the grain size composition and NNE wind direction wind Feng-cheng sediments (yellow brown soil, aeolian red clay) of similar composition, HGSC6section92aeolian sand sample sieve to the coarse-grained components (>63μm), silt (4～63μm) as main grain, modal particle size around5～6φ, coarse silt content is higher than that of fine sand, fine end frequency curve changes slowly, existence of inflection point8φ and10φ, sorting coefficient between1.40～1.57, kurtosis skewness is between2.41～3.40,0.52-0.94, on the whole, The surrounding area of Poyang Lake wind respectively sediments have far and near source in the elemental composition, but the grain size of particulate matter composition has a certain similarity.(2) Along the Poyang Lake area winter wind dominant wind direction--northeast wind channel, from north to South HGSC aeolian sand profile (select <63μ m part), LSDM yellow brown soil, yellow brown soil profile CJZ, SJP wind laterite profile, JX1wind a laterite profile5section size composition display spatial variation rule. Aeolian sand--yellow brown soil--eolian grain-size composition of thin sand, wind characteristics of yellow brown soil, peripheral distribution to the peripheral distribution of Aeolian red clay with. From the HGSC aeolian sand profile (<63μm) by LSDM, CJZ yellow brown soil profile to SJP, JX1aeolian sediment laterite profile, average grain diameter by6.22φ transition to7.16φ; fine silt fractions (4～10μm), aeolian entrainment fraction (10～15μm) content gradually increased; the standard deviation, skewness scatter diagram and the average particle size-skewness scatter three also showed a gradual transition from north to south. Combined with the dust dynamics theory and the surrounding area of Poyang Lake wind data, presumably during glacial debris in Yangtze River Valley and Poyang Lake District big bare area as Poyang Lake surrounding areas of aeolian sediments with dust, coarse-grained material accumulation in the adjacent to the Yangtze River and Lake area, periphery fine particle of matter are piling up in yellow brown soil and aeolian red clay, northern HGSC aeolian fine-grained material sand profile in May of wind direction and wind into yellow brown soil clay particle size have certain contribution. The force of the wind period, aeolian sand profile will be with fine sand (or paleosol layer), their size composition and its adjacent areas of yellow brown soil and aeolian red clay has a certain similarity. In addition, all kinds of Aeolian sediment clay fractions (<4μm) exists with the variation of latitude, secondary clay group <2μm content increased from north to south, is to reflect the weathering degree latitude effect in the region.(3) The area around Poyang Lake aeolian sediment dust particle group and secondary clay component changes reflect its by the dual role of aeolian deposits and weathering. In the glacial environment conditions, cold and dry climate, strong wind, wind sand and wind to yellow brown soil and aeolian red clay exists between the spatial variation of dust particle content on that path, the winter wind, the wind of the sediments under the direction of sediment composition contribute. In warm climates, the force of the wind, weathering, clay group sediments <2μm with the decrease of latitude from south to North showed a gradually increasing trend, Poyang Lake surrounding areas of Aeolian Sediments by weathering and pedogenesis with the decrease of latitude is gradually increasing, showed changes in weathering intensity with the latitude effect. (4) The special "narrow pipe Lake Road" terrain in northern Poyang Lake has a climate of the narrow pipe effect, caused the local climate is different, the Poyang Hunan and the northern grain size composition of sediments showed differences. The yellow brown soil of Poyang Lake surrounding areas after comparison, content of yellow brown soil between North and South in the secondary clay group<2μm points along the Yangtze River, north of the SJL and LSDM sections are less than15%, and is located in the southwest of Poyang Lake HTG section and ZSC section in18.6%-19.3%, this source of weathering intensity in latitudes under the influence of the different, weathering more southward sediment experience more intense; sand group in>63μm content, is located in the south of HTG, ZSC profile more, near source sand mixing may indicate a region of Southwest Poyang Lake there have been enough to carry sand strong wind power. Can be inferred, glacial climate conditions, the winter wind through the Jiujiang south into the Poyang Lake bottleneck in Hukou area, a sudden narrowing of the channel makes the wind suddenly increased, while dry conditions the southern lowland lake bed and the residual water friction coefficient is very small, as small on the winter wind barriers, resulting in the Hunan area of glaciation Poyang storm conditions, this storm conditions along the Ganjiang River Valley to the South and the influence to the southwest of yellow brown soil. |
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