A refractory mantle protolith in younger continental crust, east-central China: Age and composition of zircon in the Sulu ultrahigh-pressure peridotite

Jianping Zheng*, W. L. Griffin, Suzanne Y. O'Reilly, J. S. Yang, R. Y. Zhang

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    81 Citations (Scopus)

    Abstract

    Zircons have been extracted from garnet peridotite and its wall rock (gneiss), which was intersected by the pre-pilot hole of the Chinese Continental Scientific Drilling project (CCSD-PP1) in the Sulu ultrahigh-pressure (UHP) metamorphic belt. The peridotitic zircons record early Mesozoic UHP metamorphism (206Pb/238U age of 223.5 ± 7.5 Ma), but their Hf isotope compositions indicate that the protolith of the peridotite is at least Mesoproterozoic in age (minimum depleted-mantle ages [TDM] of 1.4 Ga). Zircons from the gneiss also reflect the Mesozoic metamorphism, with a cluster of 206Pb/238U ages at 224.5 ± 11.5 Ma; a trail of discordant grains indicates a protollith age older than 800 Ma, consistent with TDM model ages of younger than 1.2 Ga. The peridotitic zircons have trace-element patterns similar to kimberlitic and/or carbonatitic zircons, while those from the gneiss have affinities with zircons from syenites/monzonites. The differences suggest that the metasomatic agents that affected the peridotitic zircons were derived from the asthenospheric mantle rather than from subducted continental crust. The strong depletion of the CCSD-PP1 peridotite in basaltic components, and the relatively unradiogenic Hf isotopic compositions (e.g., - 16.3 to ∼ - 13.8 εHf) of the peridotitic zircons, indicate that the peridotitic body is a fragment of refractory Archean mantle that experienced Mesoproterozoic metasomatism and represents a tectonic intrusion into younger crust.

    Original languageEnglish
    Pages (from-to)705-708
    Number of pages4
    JournalGeology
    Volume34
    Issue number9
    DOIs
    Publication statusPublished - Sep 2006

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