Mineralogical studies on the soil genesis (3)

The clay minerals in the soil derived from limestone of the Ogoe district, Fukushima Prefecture

Abstract

1. From the mineralogical composition of the sand fractions, it is considred that the weathering products of limestone intercalating the thin layers of biotite schist were covered by dacitic volcanic ash, and further these materials were mixed by transportation. After then the mixed materials were covered by andestic volcanic ash.
2. It was confirmed that montmorillonite, hydrated halloysite, illite, gibbsite and kaolinite occur in the soil profile.
3. The weathering sequence of the parent materials seems to be as follows.
Volcanic ash influenced by the weathering of limestone→hydrated halloysite→montmorillorite (+gibbsite)