TrekGEO > Mineral Trail > Kanto region > Kanagawa pref. > Yadoriki

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Yadoriki, Matsuda city, Ashigara-Kami county, Kanagawa pref., Japan


Prehnite-Pumpellyite facies metamorphic rocks

Basaltic to dacitic tuff of the early Miocene (17 Ma) Togatake Subgroup, the bottom member of Tanzawa Group, subjected to Prehnite-Pumpellyite facies metamorphism by the Tanzawa tonalite in the late Miocene (7 Ma). The Tanzawa Group is considered as the accreted Izu island arc. The Tanzawa tonalite is I-type (Magnetite-series). Approximately 6 km apart from tonalite, the heat source. Ages of sedimentary rocks were determined by microfossils, tonalite by radiometric dating.


Outcrop of dacitic tuff of the Togatake Subgroup subjected to Prehnite-Pumpellyite facies metamorphism. The grayish-green outcrop is composed of metamorphosed tuff. The grayish-green color is due to pumpellyite. Albite and quartz spots are also observed.

Reported Minerals

  • Scolecite
  • Pumpellyite

Mineral Assemblages

  • Scolecite - Albite - Epidote
  • Pumpellyite - Albite
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