シラス台地上のレス質土壌とその堆積環境

概要

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Two layers of paleosol are recognized on the Shirasui plateau plateau in southern Kyushu. ^<14>C ages of the Lower paleosol A horizon are between 16, 900 and 18,000 yr. B. P.: the age immediately after the maximum of the Last Glacial Stage. The age of the Upper paleosol A horizon is considered to be between 11,000 and 13,000 yr. B. P., judging from the overlying tephra with the ^<14>C age of 10, 500 yr. B. P. The paleosols contain quartz as main mineral, Shirasu-derived minerals (kaolinite, plagioclase, cristobalite), and non-Shirasu-derived minerals (mica and illite, 14Å minerals). High concentration of quartz and the presence of non-Shirasu-derived minerals in the paleosols indicate that the main components of fine material in the paleosols are eolian dust from the Asian continent and the emerged continental shelf of the East China Sea. The accumulation amount of the dust (<20μm particle) for the Lower and the Upper paleosol A horizons attain to 10.5 (g/10cm^3) and 6.6 (g/10cm^3) respectively, representing the maximum and the second-maximum amount in the end of the Plei stocene in southern Kyushu.
地理科学学会の論文