飛騨神岡周辺域に産する白亜紀中期の流紋岩類： K-Ar年代と主成分組成.

Mid-Cretaceous rhyolitic bodies occur in the Kamioka area in the Hida Belt, central Japan. K-Ar age of muscovite phenocryst from a rhyolitic sheet in the middle member of the Tedori group was determined, yielding ca. 105 Ma. The rhyolitic dikes which intruded into Jurassic granitoid plutons and were altered to pottery stones were also dated at ca. 90~80 Ma. These rhyolitic bodies are thought to be examples of the manifestation of mid-Cretaceous magmatism in the Hida Belt. The relatively young age of altered rhyolitic dykes may have been partly influenced by the hydrothermal system related to the mineralization of the Kamioka Pb-Zn skarn deposit at ca. 65 Ma. [ABSTRACT FROM AUTHOR]