Analysis Of The Source Of Dune Sand In The Horqin Sandy Land

Sand material is the material basis of the occurrence and development of desert and sandy land,and its basic characteristics are determined by the initial properties of sand source material and the process of wind transport and transformation.Research and analysis the basic characteristics of sand material,it is of great significance to explore the sourch,the dynamic process of erosion,transportation and accumulation and the shaping of sand dunes.Taking sediments in the horqin sandy land as the research object,through field investigation and sampling system,make a comprehensive analysis of the grain size characteristic,particles morphology and surface structure characteristics of quartz,and then discusses the source of sand dunes.The results are as follows:(1)The horqin sandy land are mainly medium sand and fine sand,the grain size gradation of the sediments in the northern and southern regions is quite different,while the western area is similar to the eastern region,which shows that the sand source is related to the underlying material and the sedimentary dynamic environment is similar,so the combination of sand material plasmid is similar.Under fine particle fractions of sand dune,river sand is the most important contribution on sand dunes,above the medium sand particle size composition,formation sand contribution rate is large,it follows that the distribution of the surface loose river sand and the sand are likely to be the source of the sand dunes.(2)The sediments of the horqin sandy land from the west to the East,the average grain size becomes finer and the sorting becomes better.This is the result of natural sorting by sedimentary basins and is not the result of long-distance transport from the western part of the sand to the east.From north to south and from northwest to southeast,the average grain size of sediments does not change along the wind direction,but the sorting is getting better and better,shows that the sediment source of sand are different,belongs to the in situ sand,wind only reflected in the in situ sediment sorting and mixed material on the wind.(3)The average particle size and sorting coefficient of sand dune are between stratum sand and river sand,and they are very close to the mean value of the stratum sand and river sand.It is show that the sand dunes not only come from the river sand,but also come from the underlying stratum sand,which is the result of the action of the wind.Due to the long process of sand material circulation,sand dunes,river sand and stratum sand are mixed with each other,mutual conversion,and cause-and-effect relationship on both sides.(4)The sedimentary environment of sediments in the horqin sandy land is complex and diverse,which can be used to determine the source of sand dunes in the Horqin sandy land.The sediments in the western and southern areas are mostly from the alluvial-lake sediments of the surrounding rivers and lakes,the sediments in the northern area are mostly from river transport-accumulation and flood alluvialaccumulation of the surrounding mountains,the sediments in the eastern area are derived from alluvial-lacustrine sediments and the source of aeolian sediments is also obvious.(5)The surface of the quartz particles is given priority to wind action characteristics,water function features are relatively obvious,glaciation features are small,It represents the relationship of the various structures formed by wind,water and glaciers are between each other,mutual superposition.It reflects the sand dunes have experienced a variety of depositional environment and external agent combination,sand source has a diversity,both from the stream detrital material,and the underlying strata sediment.(6)From the similarity of sand dunes,river sand and strata sand,the similarity between the three is not significant,indicating that the sand dunes from the river sand and strata sand are almost equal.This is consistent with the results of sedimentary grain size,quartz particle morphology and surface structure characteristics,which shows that the source of sand dune in the Horqin sandy land is multi-source and complex.