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Yasue, Kenichi; Gozu, Chitaro*; Yanagida, Makoto*
no journal, ,
no abstracts in English
Sueoka, Shigeru; Yasue, Kenichi; Niwa, Masakazu; Hanamuro, Takahiro; Shimada, Koji; Ishimaru, Tsuneari; Umeda, Koji; Danhara, Toru*; Iwano, Hideki*; Gozu, Chitaro*
no journal, ,
Seven major granitic plutons are distributed around the Lake Biwa. On the basis of their lithofacies, chemical compositions, and radiometric ages, four of the seven plutons to the south of the Lake Biwa are thought to be related to a huge cauldron formed at ca 70 Ma, while the Otsukimiyama pluton to the east and Hiei pluton to the west are derived from volcanic front of ca 100 Ma. On the other hand, the geologic implications of the Kojaku pluton to the north have not been discussed due to luck of the radiometric ages. We are planning to report zircon fission-track age, biotite K-Ar age, and zircon U-Pb age of the Kojaku pluton, to estimate its formation age and cooling history, and to discuss their geological implications.
Sueoka, Shigeru; Yasue, Kenichi; Niwa, Masakazu; Shimada, Koji; Ishimaru, Tsuneari; Umeda, Koji; Yamada, Ryuji*; Danhara, Toru*; Iwano, Hideki*; Gozu, Chitaro*
no journal, ,
We introduce an attempt to date a fault distributed in the Kojyaku granite, Tsuruga area, by reconstructing its cooling history based on multi-system thermochronology. The U-Pb ages, zircon fission-track ages, and zircon fission-track length distributions of the fault gauge and host granitic rock indicate a common cooling history at higher temperature, whereas apatite fission-track may imply later reheating in the fault gauge. We are planning to provide more definitive discussions based on apatite fission-track length data.