Volatile components in deep magma indicated by anorthite megacryst and its inclusions from Mt. Fubo, Miyagi Prefecture

Abstract

Anorthite megacrysts in basaltic andesite from Mt. Fubo, Miyagi Prefecture were examined by EPMA-WDS and SEM-EDS. These observations revealed that anorthite contents of the megacrysts are An92-94 and small Fe-Ni-sulfides (20-50µm) were included in the megacrysts. Our results indicate that these megacrysts have grown in volatile (e.g., H₂O and S) rich and low viscosity condition.