Su Bei 4, Lake Sediment Granularity Characteristic

Subeinao Lake located in the Mao Wusu sands which was the ecological environment fragile area. On the basis of grain size and grain-size characteristics analysis of166sample from lake, meadow and sand in the Subeinao lakefront in vertical direction. Sediment particle size analysis is restore ancient climate, study ancient environment evolution of a key, according to the size and distribution characteristics can differentiate sedimentary types and geological process. It is helpful to confirm the lake, the meadow and the sand sedimentary environment, exploring sediment source and forming process of aeolian geomorphology by studying the grain-size characteristics of lakefront sediments in Mao Wusu sands. These conclusions are significant for predicting the effects of global climate change on sediments. The main conclusions are following:Sediment particles mainly includes extremely thick sand, thick sand, medium sand, fine sand, very fine powder sand silt and viscous grain. The grain size composition analysis shows that the sediments of different sedimentary bed is very close to and the sediments are mainly comprised of medium and fine sand. The medium and fine sand sediments content in the Subeinao Lake largest absolute advantage. Among different sediments of sample, the meadow sediments (70.78%) is the highest, followed by the sand sediments (70.67%) and the lake sediments (62.65%) lower part. The silt and viscous grain content of the lake sediments is the highest and the silt of the meadow sediments is the lowest. The silt content of the sand sediments is the lowest. The very fine powder sand content of the meadow sediments is the highest. The very fine powder sand content difference between the lake sediments and the sand sediments is small. The very fine powder sand content in the lake sediments is a little more than the sand sediments. The fine sand content is:the sand sediments> the meadow sediments> the lake sediments. The medium sand content is the highest in the different sample land:the meadow sediments> the sand sediments> the lake sediments. The thick sand content is: the sand sediments> the lake sediments> the meadow sediments. The extremely thick sand content is the lowest in the different sample land. The extremely thick sand content of the sand sediments is the highest and the silt of the lake sediments is the lowest. The grain size composition analysis shows that the sediments of different sedimentary bed has a certain rule. The lake sediments is divided into seven sections,the meadow and the sand sediments is divided into eight sections. It is according to the fine-grained material like viscous grain with the reduction and the thick material with the increase of their proportion. The proportion changing trend of the sediments is presentation like the spacing of the2sections. That is the first section and the third section similar, the second section and the fourth section similar.The grain size composition in the first section analysis of3different sample land shows that the meadow sediments (0～20cm) is different to the lake sediments (0～10cm) and the sand sediments.There is a contradictory trend. Sample collecting site all belong to the SuBeinao lakeside and the depth of the sediment all belong to the surface, according to the ideal of3sample land change trend should be similar.The paper analyzes reasons of the different may be because that the meadow sediments collecting site where is wetland edge in a wet into the lake of the formation of the lower reaches of rivers seasonal. The plants most of Gramineae in the meadow sample land.The Gramineae fibrous root systems is developed. The capability of soil formation is quite high that the fine-grained material like viscous grain is increase. The above reasons why in surface of the meadows sediments different to the lake sediments and the sand sediments.The grain size composition analysis shows that the sediments of different sedimentary bed is:the meadow sediments> the sand sediments> the lake sediments. The sorting parameters show that the sediments from the3sample land are poor in sorting.The sediments from the sand is slightly worse sorted than that of the lake. The meadow sediments is the bast sorted and it has a trend to medium sorted.The lake and sand sediments are extremely positive skew and extremely narrow peak normal distribution. The meadow sediments is very sharp slant and narrow peak normal distribution. The meadow sediments is has a trend to forward biased. The sand more on meadow sediments in extremely narrow distribution.