関東および信州ローム中のチタン磁鉄鉱の化学組成と共存する有色鉱物との関係  [in Japanese] The relationship between chemical composition of titanomagnetite and colored minerals coexisting with it in Kanto and Shinshu loams  [in Japanese]

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Abstract

For the purpose of contributing to tephrochronology and clarifying the mechanism of their volcanic effusion, the relationship between chemical composition of titanomagnetite and coexisting colored minerals (olivine, pyroxene, hornblende, and biotite) in the volcanic ashes and fall pumices was studied for selected samples from many horizons widely distributed in Kanto and Shinshu districts in central Japan. In the case of fall pumices, the TiO<sub>2</sub> content of titanomagnetite gradually decreases from basic fall pumice (olivine-bearing) to acidic one (hornblende-bearing), and it seems to be pos- sible to deduce the properties of rocks at the time of eruption on the basis of the TiO<sub>2</sub> content of titanomagnetite even in the horizons which were significantly weathered and lost colored minerals. On the other hand, the TiO<sub>2</sub> content of titanomagnetite in volcanic ashes has little reference to the colored minerals, and it seems to be difficult to estimate the properties of fresh ashes just after eruption.

Journal

  • Chikyukagaku

    Chikyukagaku 4(1), 1-11, 1970

    The Geochemical Society of Japan

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