西藏定结地区不同类型沙丘表层沉积物粒度特征及其环境意义OA北大核心CSTPCD

To explore the environmental significance of grain size characteristics,modern dunes in the Dinggye area of Xizang,China were sampled to analyze the grain size characteristics of surface sediments from different types of dunes.The results are as follows:(1)The grain size composition was similar between mobile and climb-ing dunes,and the grain size composition differed significantly between nebkha and the two dune types.The sur-face sediments of mobile and climbing dunes were dominated by fine and medium sands,whereas those of neb-kha were dominated by very fine sand,fine sand,and powdery sands.(2)The grain size parameters of these dunes showed different trends,with the surface sediments of mobile and climbing dunes well sorted,nearly sym-metrical,and moderately sharp,and those of nebkha moderately sorted,positively skewed,and very sharp.(3)The frequency distribution curves of mobile and climbing dunes are nearly symmetrical and single-peaked,whereas those of nebkha are bimodal;the differences in the probability accumulation curves of the surface sedi-ments of these dunes are more obvious.(4)The deposition environment of the surface sediments of these dunes is mainly dominated by wind-formed deposition,with a few river deposits.(5)A comparison of particle size charac-teristics of the surface sediments of these dunes shows that the differences in particle size characteristics are main-ly because of the joint action of sand source,vegetation cover,and wind conditions.