抄録
The origins of the parent materials in the reddish and/or yellowish fine textured soils developed in the hilly area surrounding Fukui plain, Fukui Prefecture, Central Japan were examined mainly by the measurement of the ESR-signal intensities associated with the oxygen vacancies in the fine quartz in these soils. The results are summarized as follows:
The ESR-signal intensities were 11.0 to 14.0 (unit, 1.3×1018 spin kg-1) and were very high, in all the horizons of Ohshibayama soil. These values suggested that the parent materials in all the horizons of this soil were influenced by the eolian dust brought from the Precambrian sediments in the northern part of Asia continent as stated in the case of Jingaoka soil in the Ka-Etsu plateau which was reported previously. The parent materials in the surface soils of other two soils tested in the present study were also influenced by the eolian dust brought from the Precambrian sediments area in the northern part of the Asia continent with the NW-winter monsoon during MIS2 (24-11 thousands years ago, Last Glacial Maximum). On the other hand, the ESR-signal intensities in the fine quartz in the subsoils of the Daianzenji and the Kazatani-pass soils were very low, and suggested that the parent materials in these subsoil were derived from the autochthonous Miocene tuffereceous sediments, which was coincident to the results of the previous clay-mineralogical studies. The parent materials in the middle depth horizons of four soils tested in the present study were the mixture of the autochtonous sediments and the eolian dust brought from the Precambrian sediments in the northern part of the Asia continent, because the ESR-signal intensities in them were 6.3 to 8.7 unit, and were relatively low.
