P-T evolution of Glenelg eclogites, NW Scotland: Did they experience ultrahigh-pressure metamorphism?

Krishnan Sajeev, Takahiro Kawai, Soichi Omori, Brian F. Windley, Shigenori Maruyama

    Research output: Contribution to journalArticle

    10 Citations (Scopus)

    Abstract

    Eclogites and their retrogressed equivalents from the eastern unit of the Glenelg-Attadale Inlier in NW Scotland preserve much microstructural evidence that indicates that very high-pressure/temperature eclogite facies conditions were reached, and followed by decompression and hydration during exhumation. Rutile exsolution in garnet and quartz exsolution in omphacite and titanite formed through mineral reactions during high P-T peak metamorphism. Isochemical phase diagrams modeled for samples from three different locations indicate that the outer part of the eastern unit preserves a peak metamorphic condition of c. 850-1000 °C at 18-25 kbar, whereas the central part has a similar pressure (c. 23 kbar), but a lower temperature (c. 670 °C). Due to the limitations in the phase diagram calculations the estimated P-T conditions represent the minimum conditions attained by the peak metamorphic assemblage, and the pre-exsolved peak assemblage probably stabilized at a higher pressure. This observation is strongly supported by the presence of exsolution microstructures. The present results demonstrate that the eastern unit experienced very high P-T conditions during peak metamorphism and a tight clockwise P-T trajectory and provide the first indication of possible ultrahigh-pressure metamorphism in the Glenelg eclogites.

    Original languageEnglish
    Pages (from-to)473-489
    Number of pages17
    JournalLithos
    Volume114
    Issue number3-4
    DOIs
    Publication statusPublished - Feb 1 2010

    Keywords

    • Eclogites
    • Exsolution microstructure
    • Glenelg-Attadale Inlier
    • P-T condition
    • Phase diagram
    • Scotland

    ASJC Scopus subject areas

    • Geology
    • Geochemistry and Petrology

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