Temporal variation in primary magma compositions in the northeast Japan Arc

Shigeru Yamashita, Yoshiyuki Tatsumi, Susumu Nohda

    Research output: Contribution to journalArticlepeer-review

    6 Citations (Scopus)

    Abstract

    A remarkable temporal variation in primary magma compositions has been found in the Northeast Japan arc. The trench-side magmas have become more enriched in FeO* and the backarc-side magmas have become more depleted in FeO* while retaining almost constant SiO2 levels for the last ∼20 million years. In order to understand the origin of the temporal variation, FeO* and SiO2 contents in partial melts are modeled for an adiabatically-rising mantle as a function of potential temperature and original composition of the mantle material. The result demonstrates that the primary magmas that are more depleted in FeO* were derived from the mantle materials either at lower potential temperatures or with compositions more depleted in basaltic components. A possible mechanism for the inferred primary magma variability is the change in depth intervals with time of magma production in a compositionally-layered mantle wedge; greater degrees of depletion at a greater depth is reconciled with a probable thermal regime in the mantle wedge.

    Original languageEnglish
    Pages (from-to)276-288
    Number of pages13
    JournalIsland Arc
    Volume5
    Issue number3
    DOIs
    Publication statusPublished - Sep 1996

    Keywords

    • Northeast Japan arc
    • Primary magma
    • Temporal variation

    ASJC Scopus subject areas

    • Geology

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