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

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Oisawa

Miyagase, Kiyokawa city, Aiko county, Kanagawa pref., Japan

Occurrence

Low-temperature zeolite facies metamorphic rocks

Andesitic to Dacitic tuff of the late Miocene to early Pliocene (7.5-4 Ma) Hayato Subgroup, the upper Tanzawa Group, subjected to Zeolite facies metamorphism by quartz diorite in the late Miocene to early Pliocene (10-5 Ma). The Tanzawa Group is considered as the accreted Izu island arc. Approximately 10 km apart from quartz diorite, the heat source. Ages of sedimentary rocks were determined by microfossils, quartz diorite by radiometric dating.

Oisawa

Outcrop of andesitic to dacitic tuff breccia of the Hayato Group subjected to Zeolite faices metamorphism. The green parts are tuff pebbles altered to celadonite. There are tuff beds near this outcrop, and those tuff beds turn homogeneous green by formation of celadonite. This celadonite was used as semi-precious stone in ancient time, and is often found as necklaces in old burial mounds.

Reported Minerals
  • Celadonite

Mineral Assemblages

  • Celadonite
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