- © 2016 Geological Society of South Africa
The Garies Granite is a mesocratic to leucocratic, porphyritic post-tectonic member of the Spektakel Suite in the Mesoproterozoic Namaqua-Natal Belt of western Namaqualand. It is a composite unit, showing a continuum of rock types from mesocratic porphyritic biotite granite with characteristic slender phenocrysts (Rooiberg-type) to coarse-grained equigranular leucocratic granite (Karkams-type) with few or no phenocrysts at all. Metamict zircons prevented accurate dating, but field relationships suggest the Garies Granite is synchronous to slightly younger than the spatially associated Kliphoek Granite, which has recently been dated at 1078 ± 5 Ma and 1060 ± 9 Ma. The acidic, potassic and weakly peraluminous granite yielded ɛNd values of between −1.39 and 0.61 and TDM values of between 1579 and 1710 Ma indicating a significant contribution of older crustal material to the source magma.