Properties of chemical composition of ferromagnetic minerals in middle to late pleistocene tephra in southern Kyushu, Japan: Application of the tephrochronology to the study of age of paleosol
2001
Akagi, I. (Miyazaki Univ. (Japan). Faculty of Agriculture) | Inoue, Y. | Nagatomo, Y.
Many Quaternary tephra have been widely distributed in Southern Kyushu, Japan. It will be possible to estimate of chronological data on paleosol by stratigraphical correlation of tephras, which have studied owing to recent progress in tephrochronology. The major and minor elements (Fe, Ti, Mn, V and Zn) of ferromagnetic minerals in Aso-4, Kikai-Tozurahara, Ata, Aso-3, Ata-Torihama, Kakuto, Kobayashi-Kasamori and Hiwaki tephra which are representative middle to late Pleistocene tephra in southern Kyushu were analyzed. The results obtained as follows; 1) These tephra were characterized by the chemical composition of ferromagnetic minerals. The content of Ti, Mn, V and Zn in ferromagnetic minerals were very different from every other tephra; 2) Aso-4, Kikai-Tozurahara, Aso-3, Ata-Torihama, Kobayashi-Kasamori and Hiwaki tephra were clearly discriminated by the combination of the content ratios of Zn/tFe and V/Ti. On the other hand, Ata and Kakuto tephra were clearly distinguished by the combination of the content ratios of Zn/Ti and Mn/tFe; and 3) The analysis of the chemical composition of ferromagnetic mineral allowed to identify unknown two tephra which are middle to late Pleistocene tephra existed on and under the paleosol in Hitoyoshi basin. It was shown that the properties of chemical composition of ferromagnetic minerals in these tephra serves as a good indicator for the identification of these tephras.
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