Presentation Information
[R7P-01]Petrography of syenite from Hakata Island, Geiyo Islands, Ehime Prefecture, Japan.[Presentation award entry]
*Toko FUKUI1, Satoshi SAITO1 (1. Graduate School of Science and Engineering, Ehime University)
Keywords:
Syenite,Hakata Island,metasomatic alteration
In this study, we describe field occurrences, petrographic characteristics and whole-rock chemical compositions of syenite in Hakata Island, Geiyo Islands, Ehime Prefecture, Japan. Gradual lithological variation is observed at the boundary of the syenite and surrounding granites. Aggregates of fine-grained clinopyroxene and garnet are observed. The syenite have higher Na2O contents compared to granites in the island. These observations are suggestive of syenite formation through metasomatic reactions by Na-rich hydrothermal fluids.
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