| dc.description.abstract | The Gladkop Suite (GS) granitic gneisses in the Bushmanland Domain (BD) represent one of
the oldest rock units in the Namaqua-Natal Metamorphic Province (NNMP), and are located adjacent to
the northern Richtersveld Magmatic Arc (RMA). This study represents results of a series of studies on
the granitic gneisses which make up the GS, aiming to characterize them, explain their petrogenesis and
understand their role in the development of the NNMP. The GS rocks preserved evidence of the 1.0 Ga
Namaqua Orogeny, with evidence of an older tectonic event preserved only in metasedimentary
xenoliths. The GS is made up of three distinct gneisses, namely: the Steinkopf (STK) Gneiss, the
Brandewynsbank (BWB) Gneiss and the Noenoemaasberg (NNM) Gneiss. Petrographically, these rocks
range from granites to granodiorites. Quartz, plagioclase and K-feldspar are the principal phases,
accompanied by minor amounts of biotite, hornblende, sericite, chlorite ± clinopyroxene and accessory
minerals. Geochemically, the granitoids are silica-rich, magnesian, metaluminous to weakly
peraluminous with a calcic to calc-alkalic characteristic and were generated in a high-K calc-alkaline
series. These rocks invariably show enrichment in light rare earth elements (LREE) and significant
negative Eu anomalies. All the granitic gneisses show characteristic negative anomalies in Ba, Ti, Nb, P,
Sr and Eu, and a positive anomaly in Pb in the multi-element trace element plot (spider-diagram). | en_US |
