Thermal histry of the alteration zones around hot springs at Hongu area and Totsukawa area, Southern Kii Peninsula, Southwest Japan

Hanamuro, Takahiro  ; Umeda, Koji; Takashima, Isao*; Negishi, Yoshimitsu*

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.