Abstract
Clay mineralogical characteristics of volcanic ash soils in Changbaishan and Sanjiaolongwan, Jilin Province and Wudalianchi, Heilongjiang Province, Northeast China, were investigated. The clay mineral fractions of 8 Changbai-shan pedons, 1 Sanjiaolongwan pedon, and 4 Wudalianchi pedons were characterized by the predominance of 2:1 layer silicates, kaolinite, fine-grained quartz, and opaline silica in the surface (O, OA, A, and AE) horizons. However, the C horizons of some pedons in Changbaishan were characterized by the presence of allophane and ferrihydrite, which are weathering products from Holocene tephra deposits. The Bw and BC horizons exhibited intermediate mineralogical properties between the surface horizons and the C horizon. We assumed that the predominance of 2:1 layer silicates, kaolinite, and fine-grained quartz in the surface horizons of pedons was due to the addition of tropospheric eolian dust transported from arid and semiarid regions in China and Mongolia. Oxygen isotope ratios of quartz samples substantiated this interpretation. Opaline silica identified in the surface horizons could be formed from the soil solution containing Si released from tephra by weathering. The possibility that the pedogenic process of volcanic ash soils was associated strong with the influence of tropospheric eolian dust under the cool or cold environment of Northeast China was demonstrated on the basis of clay mineralogical properties, quartz contents, and oxygen isotope ratios of fine-grained quartz.
Published Version
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