Oshuku
Ashigawa village, Fuefuki city, Yamanashi pref., Japan
Occurrence
Albite-Epidote-hornfels facies contact metamorphic rocks
Dacitic tuff of the middle Miocene (14 Ma) Ashikawa Formation, the Nishi-Yatsushiro group, subjected to Albite-Epidote facies metamorphism by the Ashikawa quartz diorite in the middle Miocene (12 Ma). The Ashikawa quartz diorite is I-type (Magnetite-series). Approximately 500 m apart from the Ashikawa quartz diorite, the heat source. Ages of sedimentary rocks were determined by microfossils, quartz diorite by K-Ar radiometric dating of biotite and hornblende.
Outcrop of dacitic tuff of the Ashikawa Formation subjected to Albite-Epidote-hornfels facies contact metamorphism. Most parts are covered with green moss. Grayish-white parts are metamorphosed tuff composed of quartz and epidote. Epidote was formed by alteration of anorthite.
Reported Minerals
Mineral Assemblages
- Epidote - Quartz
Localities
- Oshuku (Epidote)
- Mount Kanyudo (Hematite)
Related Occurrences
- Albite-Epidote-hornfels facies
- Hornblende-hornfels facies
- Pyroxene-hornfels facies
- Sanidinite-hornfels facies