A comparison between the ∼1.08–1.13 ga volcano-sedimentary koras group and plutonic keimoes suite: Insights into the post-collisional tectono-magmatic evolution of the Eastern Namaqua Metamorphic province, South Africa

Abstract

Along the eastern margin of the Mesoproterozoic Namaqua metamorphic province (NMP) of southern Africa are a bimodal volcano-sedimentary succession, the 1.13–1.10 Ga Koras Group, composed of rhyolitic porphyries and basaltic andesites, and the 1.11–1.07 Ga late- to post-tectonic granitoids of the Keimoes Suite. This review examines existing whole-rock major- and trace-element data, along with isotope chemistry (with some new isotopic data), to investigate the role these two magmatic successions played in terms of post-collisional magmatism of the eastern NMP near the boundary with the Archean Kaapvaal Craton. The Keimoes Suite comprises variably porphyritic biotite monzogranites and granodiorites, with a charnockitic member. They are metaluminous to weakly peraluminous, ferroan, and calc-alkalic.