Fate of the subducted Farallon plate inferred from eclogite xenoliths in the Colorado Plateau

Tomohiro Usui, Eizo Nakamura, Katsura Kobayashi, Shigenori Maruyama, Herwart Helmstaedt

    Research output: Contribution to journalArticlepeer-review

    109 Citations (Scopus)

    Abstract

    We present the first finding of the high-pressure mineral coesite in lawsonite-bearing eclogite xenoliths from the Colorado Plateau, United States. The presence of coesite in these xenoliths supports the hypothesis that the eclogite formed in a low-temperature-high-pressure environment such as envisaged inside subducted oceanic lithosphere. Ion-microprobe U-Pb dating of micrometer-scale zircons in the eclogites yields ages ranging from 81 Ma to 33 Ma, the two extremes in age likely indicating the age of crystallization during subduction-related metamorphism and the age of recrystallization by the host magmatic event, respectively. These observations conclusively demonstrate that certain eclogite xenoliths from the Colorado Plateau originated as fragments of the subducted Farallon plate, which had been residing in the upper mantle since the Late Cretaceous. This is the first conclusive evidence that any eclogite xenoliths can be directly linked to a known subducted plate.

    Original languageEnglish
    Pages (from-to)589-592
    Number of pages4
    JournalGeology
    Volume31
    Issue number7
    DOIs
    Publication statusPublished - Jul 1 2003

    Keywords

    • Coesite
    • Colorado Plateau
    • Eclogite xenolith
    • Farallon plate
    • U-Pb age
    • Zircon

    ASJC Scopus subject areas

    • Geology

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