Objective   In order to explore the origin of Wushan loess and understand the genetic characteristics of soils derived from this kind of parent material,

  Method   the samples form typical Wushan loess profile were analyzed through field investigation and laboratory analysis for morphology characteristics, particle composition, characteristics of major elements, other physicochemical properties and weathering indexes such as silicon aluminum ratio (Sa), chemical indices of alteration (CIA), sodium potassium ratio ( Na/K) and iron free degrees.

  Result   The results showed that: (1) The main particle composition of Wushan loess was silt, with an average content of 53.29%, which was similar to typical aeolian loess. At the same time, the contents of main major elements (Si, Al, Fe) of Wushan loess were close to those of aeolian loess in other regions, and the upper continent crust normalized patterns of major elements were also similar among them. (2) There were higher contents of organic carbon and Se, lower contents of Calcium carbonate equivalent and δ¹³C values in 100 - 140 cm soil layers, speculating that the climate was warm-wet and plant growth might have occurred during the deposition process of Wushan loess profile at depths of 100 - 140 cm. (3) For the Wushan loess profile, Sa were 8.73 - 9.17; CIA were 65.96 - 69.10; Na/K were 0.74 - 0.89; and iron free degrees were 22.88% - 29.74%. Compared with aeolian loess in other regions, the chemical weathering degree of Wushan loess was stronger than that of Luochuan loess, weaker than Xiashu loess and Chengdu clay, and very close to Hanjiang loess and Ganzi loess.

  Conclusion   Wushan loess is of aeolian origin, in a moderate chemical weathering degree, mainly desalting base, and the degree of desilication and iron aluminum enrichment was weak. There may be the same source among Wushan loess, Hanjiang loess and Ganzi loess.