我が国の土壌中に含まれる微細石英の風成塵起源について〔英文〕

概要

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The oxygen isotopic ratios of fine quartz from twenty Japanese soils developed in the last Glacial and Holocene ages are remarkably uniform (δ18O SMOW=14.1 to 16.9‰), suggesting their common origin in eolian dust; most Japanese soils have been influenced significantly by tropospheric eolian materials. The soils influenced by the eolian dust are enriched in the silt and clay fractions, especially in the top horizon of soils. Eolian silt and clay fractions have been gradually mixed with the weathered rock materials during the last Glacial age. The continuous addition of the eolian dust to the parent materials has also taken place during the Holocene age. The present findings of a widespread contribution of the eolian dust to the soil development also indicate that the Japanese Islands are situated on the fringe area of the semi-arid and arid Continent of Asia.Eolian dust also originates in river beds (TAKESAKO and KATO, 1983) and coastal sand sheets. Consequently, it seems probable that the fine quartz has the multiple origins: from Chinese Continent and the above mentioned areas.Further examination for the oxygen isotopic ratio of fine quartz should be carried out by comparing the value of the Chinese loess with those of the above mentioned two areas.
日本第四紀学会の論文