PETROGRAPHY, GEOCHEMISTRY AND MINERALISATION POTENTIAL OF THE PEGMATITES OF JANJALA AREA, NORTH CENTRAL NIGERIA

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Petrography-Geochemistry-and-Mineralisation-Potential-of-the-Pegmatites-of-Janjala-Area-North-Central-Nigeria.pdf (689.34 KB)

Date

2020-07-20

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Department of Geology and Mining, Nasarawa State University Keffi

Abstract

The petrographic, geochemical and mineralogical investigations of the pegmatites of Janjala area, North Central Nigeria was carried out with the aim of understanding its mineralization potential. Petrographic studies were conducted in the petrographic laboratory of the Department of Geology and Mining Nasarawa State University Keffi, while the geochemical analysis was carried out using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) techniques in the ACME laboratory limited, Vancouver Canada and NGSA laboratory Kaduna, Nigeria using XRF techniques. The seven (7) lithological units identified in the area consist of the biotite schist, muscovite schist, fine grained muscovite granite, medium grained biotite granite, medium grained granite, porphyritic granite and pegmatites. All the pegmatites are uncomformably emplaced and restricted to the biotite schist unit in the area around Janjala and Mahanga villages. Petrographic studies reveal the major mineral as quartz, K-feldspar, plagioclase, muscovite; while accessory minerals comprise of lepidolite, beryl, clevelandite, sericite, sphene, tourmaline and zircon. Major oxides and trace element contents indicate high fractionation and mineralization potential based on the variation plot of K2O vs Na2O, the relatively high values of Rb, Cs,Ta, Sn Nb, the K/Rb vs Rb and K/Rb vs Cs ratios which revealed that the pegmatites are relatively mineralized. Generally, the pegmatites in the Janjala area favourably compared well with other relatively mineralized rare-metal pegmatites of the North Central Nigeria, such as Wamba, Nasarawa and Keffi pegmatites.

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Pegmatite, granite, petrography, geochemistry and mineralization

Citation

Akintola, A. I. Omosanya, K. O., Ajibade, O. M., Okunlola, O. A. and Kehinde- Phillips, O. O. (2011), “Petrographic and Geochemical Evaluations of Rare Metal (Ta-Nb) Potentials of Precambrian Pegmatites of Awo Area Southwestern, Nigeria”, Baker, D. R. (1998), “The Escape of Pegmatite Dikes from Granitic Plutons: Constraints from New Models of Viscosity and Dike Propagation”, Can. Mineral., Vol. 36, pp. 255 – 263. Black, R. (1980), “Precambrian of West Africa”, Episodes, No. 4, pp. 3 – 8. Burke, K. C. and Dewey, J. F. (1972), “Orogeny in Africa.” In: Dessauvagie, T.F.J. and Whiteman, A. J. (Eds.), African Geology, University of Ibadan Press, Ibadan, pp. 583 – 608. Caby, R., Brand, J. M. L and Black, R. (1981), “Pan-African Ocean Closure and continental Collision in the HoggarIforas Segment, Central Sahara”, in Precambrian Tectonics”, Edited by a Kroner, Elsevier Amsterdam, pp 407 – 434. Cerny, P. (1982a), Petrogenesis of Granitic Pegmatites, In Granitic Pegmatites in Science and Industry, Mineralogical Association of Canada, Short Course Handbook, No. 8, pp. 405 – 461. Cerny, P. (1982b), The Tanco Pegmatite at Bernic Lake, SoutheasternManitoba,Mineralogical Association of Canada, Short Course Handbook No. 8, Granitic Pegmatites in Science and Industry, pp. 527 – 543. Cerny, P. (1991a), “Rare-Element Granitc Pegmatites, Part I: Anatomy and Internal Evolution of Pegmatite Deposits”, Geoscience Can., Vol. 18, pp. 49 – 67. Cox, K. G. Bell, G. D. and Pankhurst, R. J. (1979), ‘The Interpretation of Igneous Rocks, George, Allen and Unwen, London. Chappel,B.W. and White,A.J.R.(1974).Two contrasting granite types.Pacific Geology,8,173- 174.

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https://keffi.nsuk.edu.ng/handle/20.500.14448/5648

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