Petrology and Sr-Nd-Hf isotope geochemistry of gabbro xenoliths from the Hyblean Plateau

A MARID reservoir beneath SE Sicily?

Giovanna T. Sapienza*, William L. Griffin, Suzanne Y. O'Reilly, Lauro Morten

*Corresponding author for this work

    Research output: Contribution to journalArticle

    12 Citations (Scopus)

    Abstract

    In situ trace-element and isotopic (87Sr/86Sr) data and whole-rock Sr-Nd-Hf data on 12 gabbro xenoliths from the Hyblean Plateau (south-eastern Sicily) illustrate the complex petrogenetic evolution of this lithospheric segment. The gabbros formed by precipitation of plagioclase + clinopyroxene from a HIMU-type alkaline melt, then were cryptically metasomatized by a low-Rb, high-87Sr/86Sr fluid, and finally infiltrated by an exotic, late Fe-Ti-rich melt with 87Sr/86Sr ∼ 0.7055, carrying high concentrations of Sr, Rb and HFSE. The geochemical and isotopic features of both the metasomatizing fluid and the Fe-Ti-rich melt are compatible with their common derivation by the progressive melting of an amphibole-phlogopite-ilmenite metasomatic domain (MARID-type?) that probably resided within the subcontinental lithospheric mantle. Therefore, both the astenosphere and the lithosphere underneath the Hyblean Plateau contributed to the petrogenesis of the gabbros. Sm-Nd dating yields an age of 253 ± 60 Ma for the cumulitic pile, roughly coinciding with a hydrothermal event recorded by crustal zircons in the area. We suggest that the Hyblean Plateau suffered a thermal event - probably related to lithospheric thinning and upwelling and melting of the asthenosphere - in Permo-Triassic time (the opening of the Ionian Basin?). The induced perturbation in the lithosphere caused consequent melting of some previously metasomatised portions.

    Original languageEnglish
    Pages (from-to)1-22
    Number of pages22
    JournalContributions to Mineralogy and Petrology
    Volume157
    Issue number1
    DOIs
    Publication statusPublished - 2009

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