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Yamabuki Creek

Higashimachi-Naka, Shimo-Suwa city, Suwa county, Nagano pref., Japan

Occurrence

Greenschist facies metamorphic rocks

Small hematite deposit associated with tuff in the Late Jurassic (150 Ma) to Early Cretaceous (130 Ma) accretionary complex subjected to Greenschist facies metamorphism as a part of the high-P Sambagawa metamorphic belt in the Late Cretaceous (70 Ma). The Sambagawa metamorphic rocks is considered that it has been near the ground surface since early Paleocene (65 Ma). The metamorphic rocks has been subjected to the middle Miocene (15 Ma) granite. The granite is I-type (Magnetite-series), and approximately 200 m apart from this location. Metamorphic age was determined by K-Ar radiometric dating of muscovite.

Yamabuki Creek

An adit mined for hematite ore during World War II. Hematite is concentrated in greenschist. The adit wall is greenschist of Sambagawa Metamorphic Rocks.

Reported Minerals

  • Hematite

Mineral Assemblages

  • Green schist(Host) - Hematite

History

  • 1965: Hematite was mined as iron ore.
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