CLAY MINERALOGY OF RED-YELLOWISH SOILS DISTRIBUTED IN HILLY MOUNTAIN AREA NEIGHBORING THE EASTERN PART OF FUKUI PLAIN, CENTRAL JAPAN

Abstract

The clay-mineralogical characteristics were examined in two Yellow Brown Forest soils distributed in the hilly mountain area neighboring the eastern area of Fukui plain, Central Japan. The subsoil in one of the two soils was the buried horizons considered to be the paleosol. The results were summarized as follows: In those two soils, chlorite-vermiculite intergrade was predominant in the clay fractions, and the chlorite contents were increased in the surface soils, which were characterized by the Yellow-Brown Forest soils. The presence of chlorite-vermiculite intergrade accompanied by small amounts of chlorite and mica minerals suggested that they were influenced by the eolian dust transported from the Asian continent. Halloysite was found in the clay fractions of those soils and was derived from the autochthonous material which is the weathered tuffaceous rock. Gibbsite derived from the autochthonous material was also present in the clay fractions, and its content was especially high in the KZP soil.