中国东部沙区表层沉积物粒度特征

通过分析中国东部沙区表层沉积物粒度特征及其与风力、植被覆盖的相关性,探讨了东部沙区现代风沙沉积环境及其区域差异性。结果显示:东部沙区各沙漠/沙地粒径级配相对一致,均以细沙、中沙为主,粒度分布整体呈单峰形态,中等分选,粒度分布和分选性均与西部沙区有较大不同。风力和植被覆盖状况的差异决定了各沙地所处的风沙环境性质和风沙活动强度不同,导致东部沙区表层沉积物粒度特征存在明显的区域差异性。其中,库布齐沙漠粒度特征与该区风蚀、搬运、堆积过程频繁交替的风沙活动方式密切关联;呼伦贝尔沙地粒度特征反映了风蚀主导的风沙环境;科尔沁沙地、浑善达克沙地,毛乌素沙地粒度特征和风沙活动方式相对复杂,与这3个沙地内部风蚀主导区和沙尘沉降主导区镶嵌分布的格局有关。东部沙区表层沉积物平均粒径和分选系数均与沙地年均风速和植被总盖度双因素之间具有显著的非线性相关性。

Grain-size Characteristics of Surface Sediments in the Eastern Desert Regions of China

By analyzing grain-size characteristics of surface sediments as related to wind force and vegetation cover in the eastern sand area of China, this paper discussed the modern aeolian sedimentary environment and the regional differences. The results show that with a unimodal distribution pattern the grain-size of the surface sediments of each desert and sandy land in the eastern desert regions is similar. All of the surface sediments are mainly composed of fine sand and medium sand and moderately sorted. Both grain-size composition and sorting differ from those of the western deserts. Controlled by the properties of the aeolian environment and the intensity of aeolian activities that were determined mainly by wind force and vegetation cover, grain-size characteristics of the surface sediments exhibit regional difference in the eastern desert regions. Specifically, grain-size in the Hobq Desert implies a typical desert environment that is characterized by frequent alternating processes of wind erosion, particle transportation and deposition; In the Hulunbeir Sandy Land, it is characterized by a wind erosion dominated aeolian environment; In the Otindag Sandy Land, Horqin Sandy Land and Mu Us Sandy Land, grain-size and aeolian activities are relatively complex, which is related to the mosaic distribution pattern of wind erosion dominated areas and aeolian deposition dominated areas. Statistics shows that both the mean grain-size and the sorting of the surface sediments significantly correlated to the annual average wind speed and the total vegetation coverage in the eastern desert regions.