Water content of melt inclusions in phenocrysts using secondary ion mass spectrometer

Isoji Miyagi and Hisayoshi Yurimoto
Bull. Volcanol. Soc. Japan Ser. II

Vol. 40, 349-355 (1995)

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Abstract:

  Analytical method by secondary ion mass spectrometry, SIMS, is
developed for water micro analysis of hydrous silicate
glasses. Standard hydrous glasses are synthesized and carefully
examined their homogeneities. "Matrix effect" for the determination of
hydrogen analysis by the SIMS method is corrected using their SiO2
content (wt. %). Using the SIMS, water contents of andesitic to
rhyolitic glasses can be estimated precisely (0.5 wt. % H2O). As an
application of the SIMS analysis, water contents of melt inclusions
and matrix glasses from the Aira eruptive products are examined. The
water contents of the melt inclusions are 5 ~ 7 wt. % H2O. This is
consistent with the water contents calculated by the relationship
between water solubility and water pressure from the data of Aramaki
(1971).