Masao Ban

Abstract Volcanic rocks from the Z-To5 tephra layer of Zao volcano, NE Japan, preserve petrological information that reflects the magmatic processes under the volcano. The Z-To5 rocks were formed by the mixing of three magmas that differed in composition and phenocryst assemblage: basalt (1150–1200 °C), with high Mg (Fo c . 81 ) olivine; basaltic andesite (1020–1100 °C), with Mg-rich orthopyroxene (Mg#= c . 78) and clinopyroxene (Mg#= c . 78), lower Mg olivine (Mg#= c . 78), and calcic (An c . 85 ) plagioclase; and andesite (900–1000 °C) with Mg-poor orthopyroxene (Mg#=61–66) and clinopyroxene (Mg#=64–68), and An-poor plagioclase. The basaltic magma was formed through fractionation of Fo c . 85 olivine from a less differentiated basaltic magma during its fast ascent from the depths. The andesitic magma, which occupied a shallow magma chamber, was heated by underplating of the basaltic magma, resulting in dissolution of some minerals. Subsequently, the basaltic andesite magma was formed by mixing of the basaltic and andesitic magmas in the chamber. Petrological evidence for the rapid growth of phenocrysts in the basaltic andesite magma suggests that the magma residence time was short. The basaltic andesite magma, mixing with a small portion of the andesitic magma, was withdrawn upon eruption. The rates of these processes are inferred to be rapid based on petrological considerations.

Magma chamber

10.1144/sp304.8

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Petrologic characteristics of early part of the Okama-Goshikidake activity of the Zaovolcano.

Japan Geoscience Union (2015)

Yuki Nishi Masao Ban Teruki Oikawa Seiko Yamasaki

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Mixing-Induced Crystallization from the Mingling Magma of Saruana Lava, Chokai

日本鉱物科学会年会講演要旨集 (2012)

Takeshi Ohba H Oikawa Shigenari Hayashi Masao Ban

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Eruption history and temporal change of magmatic compositions of Kumanodake-sancho lava & pyroclastics, Zao Volcano

Naoto Ito Masao Ban

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Eruption Histories of Zao and Azuma Volcanoes and Their Magma Feeding Systems for Recent Activities

東京大學地震研究所彙報 = Bulletin of the Earthquake Research Institute, University of Tokyo (2016)

Masao Ban Yoshinori Takebe T. Adachi Ruriko Matsui Yuki Nishi

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Erratum : Records for high time-resolution volcanic eruptions:

The Journal of the Geological Society of Japan (2012)

Teruki Oikawa Yasuharu Hoshino Kazuyoshi Yamada Masao Ban Mitsuru Okuno

訂正地質学雑誌 Vol. 117，No.12の口絵（及川ほか, 2011）のFig. 4の説明文に誤りがありました．以下のようにご訂正下さい．誤） Fig. 4. Oblique aerial photograph of Zao volcano viewed from the west.正） Fig.4. Oblique aerial photograph of Zao volcano viewed from the southeast.著者一同

10.5575/geosoc.erratum_2012.03

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