Vesicle layering in solidified intrusive magma bodies: A newly recognized type of igneous structure

A. Toramaru, A. Ishiwatari, M. Matsuzawa, N. Nakamura, S. Arai

    Research output: Contribution to journalArticlepeer-review

    14 Citations (Scopus)

    Abstract

    We report a novel type of layering structure in igneous rocks. The layering structure in the Ogi picrite sill in Sado Island, Japan, is spatially periodic, and appears to be caused by the variation in vesicle volume fraction. The gas phase forming the vesicles apparently exsolved from the interstitial melt at the final stage of solidification of the magma body. We call this type of layering caused by periodic vesiculation in the solidifying magma body "vesicle layering." The presence of vesicle layering in other basic igneous bodies (pillow lava at Ogi and dolerite sill at Atsumi, Japan) implies that it may be a fairly common igneous feature. The width of individual layers slightly, but regularly, increases with distance from the upper contact. The layering plane is perpendicular to the long axes of columnar joints, regardless of gravitational direction, suggesting that the formation of vesicles is mainly controlled by the temperature distribution in the cooling magma body. We propose a model of formation of vesicle layering which is basically the same as that for Liesegang rings. The interplay between the diffusion of heat and magmatic volatiles in melt, and the sudden vesiculation upon supersaturation, both play important roles.

    Original languageEnglish
    Pages (from-to)393-400
    Number of pages8
    JournalBulletin of Volcanology
    Volume58
    Issue number5
    DOIs
    Publication statusPublished - 1996 Dec

    Keywords

    • Bubble nucleation
    • Diffusion
    • Igneous layering
    • Liesegang ring
    • Vesicle layering

    ASJC Scopus subject areas

    • Geochemistry and Petrology

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