Intrinsic conditions of magma genesis at the Lunar Crater Volcanic Field (Nevada), and implications for internal plumbing and magma ascent

Joaquin Cortes, Eugene Smith, Greg Valentine, Racheal Johnsen, Christine Rasoazanamparany, Elisabeth Widom, Mai Sas, Dawn Ruth

    Research output: Contribution to journalArticle (journal)peer-review

    16 Citations (Scopus)

    Abstract

    The northern part of the Lunar Crater Volcanic Field (central Nevada, U.S.A.) contains more than 100 Quaternary basaltic cones and maars and related eruptive products. We focused on four informal units of different ages and locations in the field to test the compositional variability and magma ascent processes within the time span of an individual eruption and the variability between very closely spaced volcanoes with different ages. Based in whole-rock chemistry, mineral chemistry and the calculation of intrinsic properties (pressure, temperature, and oxygen fugacity) we found that individual magma batches were generated in the asthenospheric mantle from a heterogeneous garnet lherzolite/olivine websterite source by ~3–5% partial melting. Each magma batch and temporary deep reservoir was a separate entity rather than part of a continuous long-lived reservoir. Magmas ascended relatively fast, stalled and crystallized in the uppermost several kilometers of the mantle near the base of the crust and some also stalled at mid-crustal levels with minor or no geochemical interaction with surrounding rocks. Our data also suggest that volcanoes erupting within certain time windows had similar source characteristics and ascent processes whether they were located within a few hundred meters of each other or were separated by many kilometers.
    Original languageEnglish
    Pages (from-to)396-413
    Number of pages18
    JournalAmerican Mineralogist
    Volume100
    Issue number2-3
    Early online date12 Feb 2015
    DOIs
    Publication statusE-pub ahead of print - 12 Feb 2015

    Keywords

    • Lunar Crater Volcanic Field
    • geothermobarometry
    • mineral chemistry
    • monogenetic volcanism
    • whole-rock chemistry

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