An Olivine-free mantle source of Hawaiian shield basalts

A.V. Sobolev, A.W. Hofmann, S.V. Sobolev, I. Nikogosian

    Research output: Contribution to JournalArticleAcademicpeer-review

    Abstract

    More than 50 per cent of the Earth's upper mantle consists of olivine and it is generally thought that mantle-derived melts are generated in equilibrium with this mineral. Here, however, we show that the unusually high nickel and silicon contents of most parental Hawaiian magmas are inconsistent with a deep olivine-bearing source, because this mineral together with pyroxene buffers both nickel and silicon at lower levels. This can be resolved if the olivine of the mantle peridotite is consumed by reaction with melts derived from recycled oceanic crust, to form a secondary pyroxenitic source. Our modelling shows that more than half of Hawaiian magmas formed during the past 1 Myr came from this source. In addition, we estimate that the proportion of recycled (oceanic) crust varies from 30 per cent near the plume centre to insignificant levels at the plume edge. These results are also consistent with volcano volumes, magma volume flux and seismological observations.
    Original languageEnglish
    Pages (from-to)591-597
    Number of pages6
    JournalNature
    Volume434
    Issue number31
    DOIs
    Publication statusPublished - 2005

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