Grain Size and Geochemical Characteristics of Overlying Soil on Periglacial Landforms in Eastern Liaoning
The grain-size,major elements and microelements of the overlying soil in the typical periglacial landform in Mt.Laotudingzi have been analyzed.The results showed that most of the soil particles were fine,the mean grain size ranged from 5.41Φ to 6.95Φ with an average of 6.45Φ,and the soil particles were made up of clay (20.79％) and silt (69.54％) and sand (9.67％).The distribution of grain sizes varied in different soils,landforms and aspects.The geochemical composition of soil elements are mainly dominated by SiO2 (average value 45.60％),Al2O3(12.90％),Fe2O3(3.90％) and K2O (2.17％),and the total proportion of them may reach up to 73.36 ％,which indicates that the silicate and aluminosilicate can be found widely in the soil.Under the condition of long-term chemical weathering,the amount of water soluble Ca leaching significantly increased,and it is the same as Na,P,Sr.However,the elements for low chemical reactivity are enriched at the same phase,such as Mn,Ti,Cu and Zn,and the transference of other elements is not obvious.All of the elements have been standardized by UCC.In addition,the correlation between grain-size and a few elements was observed,which could be interpreted that elements such as K,Na,Sr and Ba distributed widely in sandy soil and gradually dropped off in silt soil,while the element Ti was just reverse.The chemical index of alteration (CIA) was widely used as the index ascertaining the degree of chemical weathering,the value here ranged from 57.41 to 70.44 with an average of 65.50.With the addition of value of Rb/Sr,which ranged from 0.35 to 1.54 with an average of 0.70,it was reflected that the soil was slightly weathered and suffered long-term dry and cold climate.The introduction of the diagrammatize of A-CN-K made the research on chemical weathering intensity more direct and intuitive,as was indicated in the graph,the weathering level of samples was at mid-late stage of lower chemical weathering which was characterized by leaching of Na,Ca and enriching of Al.
periglacial landformMt.Laotudingzielement geochemistrygrain sizechemical index of alteration
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