Jebba area southwestern Nigeria forms part of the Nigerian basement complex which lies in the Neoproterozoic PanAfrican mobile belt. It is underlain by several lithological units among which is a polydeformed granitic gneiss. This rock has been dated by LA-ICP-MS yielding a concordant U-Pb zircon age of 2207 ± 20 Ma indicating the crystallization age of the granite protolith. This early Rhyacian age and its affinity with within-plate granites indicates emplacement during crustal extension and rifting preceding the main phase of the Eburnean orogeny. The strong, early, shear fabric, S 1 , in the rock is interpreted to be also of Paleoproterozoic age i.e. imprinted during the Eburnean orogeny. The Jebba granitic gneiss is thus correlatable with the widely abundant Paleoproterozoic granitic magmatism now represented by many orthogneisses and documented in other parts of southwestern Nigeria, the West African craton, the Borborema Province, the Gurupi Belt, Sao Luis craton and Sao Francisco craton in Brazil.

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Synopsis The metasedimentary rocks of the Loch Laggan-Upper Strathspey area form part of the Grampian Division of the Caledonides in the Grampian Highlands. They comprise two lithostratigraphic successions, the Glenshirra and the Corrieyairack successions, which are separated by a zone of high strain, the Gairbeinn slide. Both successions consist dominantly of non-calcareous clastic metasediments. They may be correlated with similar lithostratigraphic units in the Loch Killen and the Corrieyairack Pass areas. The two successions share a similar deformational history and were both subjected to amphibolite facies metamorphism. A sub-horizontal foliation associated with an early isoclinal folding which is intensely developed in the vicinity of the Gairbeinn slide has been refolded by tight, upright, NE-SW trending folds, which have in turn been refolded by open folds with generally NW-SE trending axial traces. The absence of the Gairbeinn Pebbly Semi-psammite described from the Corrieyairack Pass area by Haselock et al. (1982) may be attributed either to tectonic excision during the sliding or to lateral facies variations.

Aderan area, southwestern Nigeria is underlain by metaigneous and metasedimentary rocks which have been intruded by granitic rocks of probable Pan-African (ca. 600 Ma) age. Four types of granitic rocks have been identified in the area, including granitic gneisses, medium-grained granite, porphyritic granite and granodiorite. Geochemical analysis show that the rocks are largely calc-alkaline. The granodiorite is less siliceous and more calcic, and also contains less Ba, Nb and Rb, and more Sr, Ce and La than the granites. Tectonically, the rocks classify as volcanic arc and syn-collisional and possibly late-to- post-collisional granitic rocks with respect to the Pan-African orogeny. Chemical characteristics indicate that these rocks were derived from partial melting of mafic to semi-pelitic (metasedimentary) crustal rocks under conditions of intermediate oxygen fugacity and activities of H₂O.