A comment on ultrahigh-temperature metamorphism from an unusual corundum + orthopyroxene intergrowth bearing Al–Mg granulite from the Southern Marginal Zone, Limpopo Complex, South Africa, by Belyanin et al.
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Studies on the Southern Marginal Zone (SMZ) of the Limpopo Belt have generally concluded that this terrain was affected by a single granulite-facies metamorphic event at 2.67–2.66 Ga (Kröner et al. 2000; Kreissig et al. 2000; Zeh et al. 2005; Elington and Armstrong 2004; Stevens and Van Reenen 1992a, b; Barton and van Reenen 1992; Barton et al. 1992; Van den Berg and Huizenga 2001; Rigby et al. 2008), with peak metamorphic conditions of 7.5–9.5 kbar and 800–850 °C. In their recent paper, Belyanin et al. (2012) propose an ultrahigh-temperature (UHT) metamorphic event in the SMZ, with peak metamorphic conditions in excess of 1,000 °C at approximately 12 kbar. Similar conclusions were proposed by earlier work on the same rock (Belyanin et al. 2010). The proposed UHT conditions are based on Al-rich orthopyroxene and ternary feldspar thermometry using reintegrated feldspar compositions. This evidence is derived from a single outcrop containing unusual aluminous layers within...
KeywordsMetamorphic Event Gray Gneiss Peak Metamorphic Temperature Feldspar Composition Southern Marginal Zone
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