摘要
In order to understand the pedogenisis process of alpine meadow soil in Amdo area,northern Tibetan Plateau,we investigated the granulometric composition and physico-chemical properties of alpine meadow soils from eight soil profiles.The results indicate that alpine meadow soils show bimodal distribution patterns with dividing point as about 20 μm.The main peak values are 90 μm,while the second peaks exhibit broad tail with the peak values 3-6 μm.The compositions of various grain size fractions(<2 μm、2-20 μm、20-300 μm、300-2 000 μm) change a little with depth at the soil profiles.The alpine meadow soils mainly consist of very fine sand with mean grain size 60-90 μm.Compared to the loess from Chinese Loess Plateau and eastern Tibetan Plateau,and the Chengdu Clay in the Sichuan Basin,the alpine meadow soils are coarser.Generally,alpine meadow soils in the present study presented a thick layer,homogeneous structure,without gravels,a complete lack of visible bedding,and a clear transition with underlying relics of paleo-weathering crust.Therefore,we propose that the parent materials of alpine meadow soils in Amdo region are aeolian deposits.The aeolian dust aggradation plays an important role in the pedogenesis process of the alpine meadow soils.