Geochronology of Archaean and Proterozoic events in the Ammassalik area, South-East Greenland, and comparisons with the Lewisian of Scotland and the Nagssugtoqidian of West Greenland

F. Kalsbeek, H. Austrheim, D. Bridgwater, B.T. Hansen, S. Pedersen, P. N. Taylor

    Publikation: Bidrag til tidsskriftArtikelForskningpeer review

    76 Citationer (Scopus)

    Abstrakt

    The Ammassalik area in South-East Greenland forms a link between the Precambrian terrains of West Greenland and northwest Scotland. It consists mainly of Archaean orthogneisses reworked during a Proterozoic tectonothermal event. Proterozoic ortho- and paragneisses, major leuconorite-charnockite complexes, suites of metadolerite dykes and posttectonic granites also occur. SmNd, RbSr, PbPb and zircon UPb isotope data yield ages of ∼ 3.0-2.8 Ga for Archaean basement gneisses, 2.2-2.1 (?) Ga for Proterozoic gneisses, 1.9-1.8 Ga for the Proterozoic reworking, 1.89 Ga for the leuconorite-charnockite complexes, and 1.7-1.6 Ga for the late granites. Proterozoic reworking has disturbed most Archaean isotope systems, and contamination with Archaean material makes dating of Proterozoic rocks difficult. In several cases discordant dates are obtained from different isotope systems. The chronologies of the Lewisian complex of Scotland and the West Greenland Nagssugtoqidian mobile belt compare closely with that of the Ammassalik area, and support the correlation between these areas suggested by earlier studies. There are, however, also major differences between the Nagssugtoqidian and the mobile belt in the Ammassalik area, and precise correlation across the Inland Ice of Greenland is still ambiguous.

    OriginalsprogEngelsk
    Sider (fra-til)239-270
    Antal sider32
    TidsskriftPrecambrian Research
    Vol/bind62
    Udgave nummer3
    DOI
    StatusUdgivet - jun. 1993

    Programområde

    • Programområde 5: Natur og klima

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