4.2 Ga zircon xenocryst in an Acasta gneiss from northwestern Canada: Evidence for early continental crust

Tsuyoshi Iizuka, Kenji Horie, Tsuyoshi Komiya, Shigenori Maruyama, Takafumi Hirata, Hiroshi Hidaka, Brian F. Windley

    Research output: Contribution to journalArticlepeer-review

    153 Citations (Scopus)

    Abstract

    Evidence for the existence of continental crust older than 4.06 Ga has so far been obtained only from zircons in the Yilgarn Craton of Western Australia. In this paper we report the first occurrence of a very old zircon with a U-Pb age of 4.2 Ga in the Acasta Gneiss Complex of northwestern Canada, based on a laser ablation-inductively coupled plasma-mass spectrometry and sensitive high-resolution ion microprobe study. The U-Pb data reveal that the 4.2 Ga zircon occurs as a xenocryst in a 3.9 Ga granitic rock. Trace element compositions of the xenocryst suggest that it crystallized from a granitic magma. Our results, suggesting the existence of granitic rocks outside the Yilgarn Craton at 4.2 Ga, imply that granitic continental crust was more widespread than previously thought, and that it was reworked into Early Archean continental crust.

    Original languageEnglish
    Pages (from-to)245-248
    Number of pages4
    JournalGeology
    Volume34
    Issue number4
    DOIs
    Publication statusPublished - Apr 1 2006

    Keywords

    • Acasta gneiss complex
    • Ancient zircon
    • Crustal reworking
    • Hadean
    • Laser ablation-inductively coupled plasma-mass spectrometry
    • Sensitive high-resolution ion microprobe
    • U-Pb dating

    ASJC Scopus subject areas

    • Geology

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