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A magmatic age and four successive metamorphic events recorded in zircons from a single meta-anorthosite sample in the Central Zone of the Limpopo Belt, South Africa

posted on 21.06.2016 by H. Mouri, M.J. Whitehouse, G. Brandl, H.M. Rajesh

Ion microprobe U–Th–Pb analyses combined with cathodoluminescence imaging of zircons from a meta-anorthosite from the Central Zone of the Limpopo Belt record five distinct events. The most concordant ages of cores of zircon yielded a weighted mean 207Pb/206Pb age of 3344 ± 3.6 Ma, representing the protolith age. The unzoned overgrowths yielded four discrete groups with weighted mean 207Pb/206Pb ages of 3150 ± 15 Ma, 2614 ± 4 Ma, 2488 ± 22 Ma and 2009 ± 28 Ma, representing four possible metamorphic events in the Central Zone. This is the first time that a succession of several metamorphic events has been demonstrated in a single rock-type from the Limpopo Belt.