S1: Earth materials science in igneous processes (Special Session)

[S1-05] Melt inclusions in a gabbro xenolith of the Izu-Oshima 1986 eruption

*Hidemi Ishibashi¹, Oida Ryoya¹, Atsushi Yasuda², Natsumi Hokanishi², Tatsuro Chiba³ (1. Shizuoka Univ., Sci, 2. Univ. Tokyo, ERI, 3. Asia Air Survey)

Keywords:Melt inclusions, Crystal mush, gabbro, Izu-Oshima, eruption

We investigated compositions of interstitial melt (IM) and melt inclusions (MI) in a gabbro xenolith of the Izu-Oshima 1986 eruption. The IM shows striped patterns of chemical heterogeneity with compositions similar to those found in the 1986 B magma indicating interstitial melt mixing in a crystal mush. MIs show constant K/Ti and Ca/Al ratios, which values are the same with those of magmas with SiO₂ <56 wt.% of Izu-Oshima volcano, indicating the original interstitial melt had SiO₂ < 56wt.%.