摘要：The ortho- and paraderived metamorphic formations of the Yaoundé series belong to the southern domain of the North Equatorial Pan-African Fold Belt. Para-derived formations of granulitic facies, which, unlike the other granulitic domains in the world, still contain preserved sedimentary features. These include the lithological banding which constitutes intercalation of garnet and kyanite-rich gneisses and quartzites, sometimes bedded, this banding of sedimentary origin is accentuated by the D1 tangential deformation which transposes the S0 bedding into foliation; the P1 intrafolial folds with horizontal fold axis and parallel to the bedding; lenticular structures marked by horizontal quartzite veins or boudins parallel to S0/S1 or S0/S1/S2 foliations, intercalated between the garnet and kyanite-rich gneisses, and sometimes lenses of garnet and kyanite-rich gneisses intercalated between the quartzites. They are either syn-D1 (quartzite or banded quartzite) sometimes transposing S0 stratification, or syn-D2 (quartzite, garnet-rich quartzite, granitic leucosome) linked to the in-situ partial melting of the garnet and kyanite-rich gneisses. The post-metamorphic and recent rock splitting, in contact with banded quartzite, quartzitic gneiss and other gneiss types, reflects an original pile of sedimentary formations of varied composition. The brittle (competent) behaviour of quartzite compared to the garnet and kyanite-rich gneisses which is rather ductile suggests the original pelitic nature for the garnet and kyanite-rich gneisses and sandstone for quartzites.
