Section 2 Proterozoic orogenies, mag matism, and related metallogeny
The only Proterozoic orogeny which was widespread throughout Africa was the Pan-African Orogeny. This orogeny is believed to represent the accretion of various terranes to form Gondwanaland.
Later Phanerozoic magmatism discussed in Section 3, and the controls on thedirections of continental rifting (section 4) are very much dependent on the structures created in late Precambrian times. It is not surprising therefore that earlier Proterozoic orogenies are often restricted to more localized regions of Africa confined to particular terranes. Nevertheless there is still considerable debate concerning the age relationships of old orogenic events.
The Kibaran cycle (approximately 1400 to 950 Ma ago) is yet another orogeny localized to central and south Africa, but which is responsible for the development of major structures, the evolution of characteristic magma types, and specific suites of ore minerals. There is also substantial evidence accumulating that just after the close of the Kibaran there was a period of alkaline magmatism developed along rift-like lineaments. These same lineaments were later exploited by Phanerozoic activity.
In this Section DeCarvahlo provides good evidence for Kibaran structures and magmatism in Angola. The evolution of the intracontinental Kibara belt is considered from the metallogenic point of view by Pohl. Its earlier history comprised of the deposition of a very thick psammo-pelitic sedimentary pile with some intercalated volcanics about 1200 Ma. This deformation created essentially upright structures, which appear to be strongly controlled by rigid basement blocks. Metamorphism and the intrusions of granites were more intense in anticlinal structures. From about 1000-950 Ma a renewed compressive phase was associated with the intrusion of LIL enriched 'fin' granites with pegmatites and quartz veins containing Sn,W,Nb/Ta,Be, and Li. This mineralization shows a pronounced structural control with a clear symmetry relation to N-S trending 0 1987 by John Wiley & Sons, Ltd