Petrological evolution in the roof of the high-grade metamorphic Central Zone of the Limpopo Belt, South Africa

Abstract

In this study we present new petrological results from the Endora Klippe in the Central Zone of the Limpopo Belt, which may result from horizontal tectonics during the Proterozoic at c. 2.0Ga. Microstructures, assemblages and garnet zonation patterns observed in metapelitic rocks provide evidence that the Endora Klippe rocks underwent a contemporaneous pressure–temperature increase from c. 600°C/5kbar to 650°C/6.5kbar. This is inferred by the use of conventional geothermobarometry and interpretations based on quantitative phase diagrams in the system MnO–(TiO2)–(CaO)–(Na2O)–K2O–MgO–Al2O3–SiO2–H2O. Thus, the petrological results indicate that this part of the Central Zone only underwent a medium-grade metamorphic overprint during a single orogenic event and was never affected by granulite-facies metamorphism, as reported from other parts of the Limpopo Belt. The inferred P–T path, in combination with previous structural and petrological results, leads to the conclusion that the area surrounding the Endora Klippe forms the roof zone of the c. 2.0Ga old granulite-facies rocks forming wide parts of the Limpopo Central Zone.