Loessial soils of Priangaria, Transbaikalia, Mongolia, and northwestern China

Comparative analysis of loessial soils from Priangaria, Transbaikalia, western Mongolia, and northwestern China investigated the differences in genesis, microstructure, plasticity and swelling, and collapsibility. Priangarian loess-like deposits formed through a 'combined' model, where during sedimentation individual primary layers of aeolian origin were deposited in a general background of deluvial deposits. Successive strata with differing aeolian additions were the media for soil formation. Microstructure is aggregated skeletal in all areas. There is a similarity between the microstructure parameters and the structural model of the loessial soils of Priangaria and northwestern China, and between soils of Transbaikalia and Western Mongolia. The mineral composition, particularly smectite, and the coefficient of freedom of the fine-clay fraction are the factors controlling swelling. The loessial soils of Transbaikalia, Western Mongolia, and northwestern China exhibit collapsibility. In Priangaria, the manifestation of this property is different, resulting from the climatic zonation and the differences in genesis.