The Kaigas and Numees formations, Port Nolloth Group, in South Africa and Namibia
Hartwig E. Frimmel, 2011. "The Kaigas and Numees formations, Port Nolloth Group, in South Africa and Namibia", The Geological Record of Neoproterozoic Glaciations, Emmanuelle Arnaud, Galen P. Halverson, Graham Shields-Zhou
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The Port Nolloth Group makes up the eastern, external part of the Pan-African Gariep Belt (Port Nolloth Zone) in southern Namibia and western South Africa. It contains two glaciogenic diamictite units, the older Kaigas Formation and the younger Numees Formation, with intercalated and overlying carbonate-dominated units. Available chemostratigraphic information include O, C and Sr isotope data. Micropalaeontological and geochronological data point to an early Cryogenian age (c. 750 Ma) of the Kaigas Formation and possibly a middle Ediacaran age (c. 580 Ma) for the Numees Formation. The former was deposited in an evolving, but eventually failed, continental rift on the western flank of the Kalahari Craton, probably at low latitude. The Numees Formation is a laterally continuous, up to 600-m-thick glaciomarine deposit for which a passive continental margin setting has been suggested. Alternatively, based on more recent data, the depositional setting might have been a back-arc basin. The eroded remnants of the corresponding arc are present in the Dom Feliciano Belt.