- 著者
-
山崎 誠子
梅田 浩司
- 出版者
- 一般社団法人 日本鉱物科学会
- 雑誌
- 岩石鉱物科学 (ISSN:1345630X)
- 巻号頁・発行日
- vol.41, no.2, pp.39-46, 2012 (Released:2012-05-04)
- 参考文献数
- 60
- 被引用文献数
-
6
15
6
The cooling history of the Crateceous Toki granite, exposed in the eastern Sanyo Belt, Central Japan, was constructed from various geochronological data. The granite yields K-Ar biotite ages of 74±2 to 72±2 Ma (±1σ) and K-Ar hornblende ages of 75±4 to 74±4 Ma, which are concordant with a previously reported Rb-Sr whole-rock isochron age. Fission-track ages of zircon and apatite in the granite give ages 73±3 to 64±3 Ma and 40±4 to 37±4 Ma, respectively. These above thermochronological data suggests two distinctive cooling stages for the Toki granite; 1) a first rapid cooling stage in which the granitic magma was cooled to the temperature of host rock soon after intrusion at depths of 5-7 km in the upper crust, and 2) second slow cooling stage (7-9 °C/m.y.) associated with the uplift and subsequent erosion of the granite intrusion after ∼ 70 Ma.