Field Features And Mode Of Emplacement Of Pegmatites Of Keffi Area, North Central Nigeria
Tanko, I.Y., Adam, M., Dambring, P.D
Keywords: Pegmatites, emplacement, petrogenesis, characterisation and classification
Abstract: The Keffi area of North Central Nigeria hosts numerous pegmatite bodies which are related to the surrounding granitic intrusions islocated about 45 km east of the Federal Capital Territory, Abuja Nigeria. Petrological investigation of the pegmatites and surrounding host rocks aimed at characterising and understanding field relations and mode of emplacement of the rocks with a view to assess their mineralisation potentials were carried out. From the field observations the pegmatites were characterised into: (1) Pelitic schist-amphibolite hosted pegmatites and (2) Granitoids (orthogneisses) hosted pegmatites, and the granites into (1) the Bakin Ayini (biotite) granites, (2) the Angwan Madugu (biotite-muscovite) granites and (3) the Sabongida (biotite-muscovite) granites. It is clear that those discordantly emplaced in pelitic schists varied in shape and size with length and width ranging from (400-2000m) and (2-20m) respectively, some are huge, isolated, sill-like and flat-lying, whilst those hosted in orthogneisses are narrow, ranging in length (40-1000m) and width (1-4m), crosscutting and vertically oriented along shear zones, which suggest passive emplacement
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