基于沉积物粒度及其砾石盖度的沙砾质地表分类特征

Characterization of Sandy Gravelly Surface Classification Based on Sediment Grain Size and Its Gravel Cover

地表沉积物粒度与砾石盖度是影响戈壁地表风蚀沙尘释放的重要地表参数。本研究以苏宏图不同类型戈壁为研究区域,通过野外观测、室内粒度分析和数字图像解译,定量分析了戈壁的粒度及砾石盖度参数,结果表明:(1)平均粒径(M_(Z))、分选系数(σ_(0))、偏度系数(S_(K))、峰度系数(K_(G))与全粒径参数(C、μ)指示了沙砾质地表成因的一致性。(2)全粒径参数(μ、Dc)可表达地表的异质性;粗砾质地表(μ=0.004~0.087,μ=0.050;Dc=0.540~3.084,Dc=1.444),中砾质地表(μ=0.001~0.186,μ=0.078;Dc=0.630~2.740,Dc=1.388),细砾质地表(μ=0.002~0.117,μ=0.070;Dc=0.054~1.270,Dc=0.646);3种沙砾质地表其砾石盖度百分含量平均值分别为16.01%、4.53%和4.44%。(3)基于砾石盖度、沉积物粒度组分、MZ、Dc间的关联关系,可作为沙砾质戈壁地表进行分类的指标性参数。

Surface sediment grain size and gravel cover are important surface parameters affecting the release of wind eroded sand and dust from the Gobi surface.In this study,different types of Gobi in Suhuntu were used as the study area,and the grain size and gravel cover parameters were quantitatively analyzed by field observation,indoor grain size analysis and digital image interpretation.The results showed that(1)the average grain size(M_(Z)),sorting coefficient(σ_(0)),skewness coefficient(S_(K)),kurtosis coefficient(K_(G)),and full-grain size parameter(C,μ)indicated the consistency of sandy-gravelly surface genesis.(2)The full grain size parameters(μ,Dc)can express the heterogeneity of the surface:for coarse gravelly surface,the range ofμwas 0.004−0.087,with an average of 0.050,and the range of Dc was 0.540−3.084,with an average of 1.444.for medium gravelly surface,the range ofμwas 0.001−0.186,with an average of 0.078,and the range of Dc was 0.630−2.740,with an average of 1.388.While for fine gravelly surface,the range ofμwas 0.002−0.117,with an average of 0.070,and the range of Dc was 0.054−1.270,with an average of 0.646.The mean values of gravel cover for the coarse gravelly surface,medium gravelly surface,and fine gravelly surface were 16.01%,4.53%,and 4.44%,respectively.(3)Based on the correlation between gravel cover,sediment size fraction,MZ and Dc,it can be used as an index parameter for the classification of sandy gravelly Gobi surfaces.