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Hanamuro, Takahiro; Umeda, Koji; Takashima, Isao*; Negishi, Yoshimitsu*
Ganseki Kobutsu Kagaku, 37(2), p.27 - 38, 2008/03
The high temperature hot springs such as in Yunomine and Tosenji and the hydrothermal alteration zones of the Hongu area are distributed in the southern part of Kii peninsula, though no Quaternary volcanoes exist. In this research, it has aimed to understand the heat history that the rocks received by the measurement technique of several dating methods for distributed Hongu area and Totsukawa area in the high temperature hot springs and the alteration zones. As a result of the TL, FT and K-Ar dating, after the activity of the high temperature alteration until tens of millions of years ago, the activity of the relatively low temperature alteration from at least hundreds of thousands of to tens of thousands of years ago in Hongu area and Totsukawa area. These thermal histories can be understood by combining the measurement techniques of several dating methods.
Umeda, Koji; Hanamuro, Takahiro; Yamada, Kunimi; Negishi, Yoshimitsu*; Iwano, Hideki*; Danhara, Toru*
Radiation Measurements, 42(10), p.1647 - 1654, 2007/11
Times Cited Count：3 Percentile：25.51(Nuclear Science & Technology)Fission track dating of zircon and apatite samples from the altered host rocks around three hot springs were carried out in order to elucidate the thermochronology of the hydrothermal system in this non-volcanic region. The apatite FT ages from the altered host rocks around the hot springs ranged from 2.7 to 5.6 Ma, which are significantly younger than the 12 Ma age of the non-altered host rocks far from the hot springs. In the southern Kii Peninsula, therefore, it is obvious that the non-volcanic hydrothermal activity already has been ongoing since around 6 Ma.
Tomiyama, Shingo*; Umeda, Koji; Hanamuro, Takahiro; Takashima, Isao*; Hayashi, Shintaro*; Negishi, Yoshimitsu*; Masudome, Yukiko*
Ganseki Kobutsu Kagaku, 36(4), p.111 - 121, 2007/07
To clarify a progress history of the alteration accompanied by Mutsu-Hiuchidake volcanic activities, the study on distribution and characteristics of alteration zones and alteration dating at the Mutsu-Hiuchidake Volcano. The results of alteration zoning and alteration dating suggest that alteration zones generated by hydrothermal activities accompanied by Mutsu-Hiuchidake volcanic activities are distributed along the fracture zones and enlarged by fractures or highly permeable zones in the body of volcano and basement. The result of measurement of homogeneous temperatures of fluid inclusion suggests that the highest temperature of these hydrothermal alterations is about 200 to 250
C.
