Constraints on mantle source and interactions from He-Sr isotope variation in Italian Plio-Quaternary volcanism.

Pasquale Nuccio, Mauro Martelli, Stuart, Ellam, Nuccio

    Risultato della ricerca: Articlepeer review

    49 Citazioni (Scopus)

    Abstract

    [1] Helium isotope ratios of olivine and pyroxene phenocrysts from Plio-Quaternary volcanic rocks fromsouthern Italy (seven Aeolian Islands, Mt. Vulture, Etna, Ustica, and Pantelleria) range from 2.3 to 7.1 Ra.Importantly, the phenocryst 3He/4He correlate well with whole rock Sr isotopic composition (0.70309–0.70711), reflecting the mixing of two sources. A significant contribution of He from crustal contaminationis recorded only occasionally (e.g., pyroxenes from Vulcano). When merged with data from the RomanComagmatic Province, a remarkably strong near-linear He-Sr isotope correlation is apparent. The generalnorthward decrease in 3He/4He corresponds to an increase in 87Sr/86Sr (and a decrease in 143Nd/144Nd and206Pb/204Pb) that is due to increasing metasomatic enrichment of the mantle wedge via subduction of theIonian-Adriatic plate. Calculations based on the ingrowth of 4He in the wedge and on the 4He content ofthe subducting crust show that mechanisms of enrichment in radiogenic He are effective only if the wedgeis strongly depleted in He relative to best estimates of the depleted mantle. This can be accommodated ifthe process of metasomatism by the subduction fluids depletes the mantle wedge. The 3He/4He ofPantelleria, Etna, Iblei, Ustica, Alicudi, and Filicudi basalts (7.0 ± 0.6 Ra) define the mantle compositionleast affected by subduction-related metasomatism. Although these volcanoes are from a variety of tectonicregimes (subduction-related, intraplate, rifting), their similarities suggest a common origin of geochemicalfeatures. Their characteristics are consistent with a HIMU-type mantle that either is younger than the Cook-Austral island end-member or has a lower 238U/204Pb.Q02001, doi:10.1029/2007GC001730ISSN: 1525-2027ClickHereforFullArticleCopyright
    Lingua originaleEnglish
    pagine (da-a)1-16
    Numero di pagine16
    RivistaGeochemistry, Geophysics, Geosystems
    Volume9
    Stato di pubblicazionePublished - 2008

    All Science Journal Classification (ASJC) codes

    • Geophysics
    • Geochemistry and Petrology

    Fingerprint Entra nei temi di ricerca di 'Constraints on mantle source and interactions from He-Sr isotope variation in Italian Plio-Quaternary volcanism.'. Insieme formano una fingerprint unica.

    Cita questo