Geochemical Characterization and Rare-Metals (Ta-Nb) Mineralization Potentials of Pegmatites Around Lokoja, Central Nigeria
Pegmatite bodies intruding the basement complex as dykes and large veins around Lokoja were studied geochemically to characterise them and determine their rare metals mineralization potentials. Thin sections studies show they are predominantly made up of quartz, microcline, muscovite, opaque minerals, occasional biotite and some minor/accessory beryl, apatite and zircon. Composite whole-rock samples were analysed for major, trace and rare earth elements using X-Ray Fluorescence Spectrometer (XRF) and Inductively Coupled Plasma Mass Spectrometer (ICP-MS). The results reveal the pegmatites are considerably siliceous with SiO2 values of 69.00% to 74.60%. Al2O3 values are relatively moderate (14.80% to 19.60%). Na2O and K2O abundances are low with ranges of 2.32% – 5.93%, 1.22% – 11.00% respectively. MgO abundances are generally low (0.03 – 0.07%). Fe203 values are also low; ranging from 0.31% to 1.16%. Alumina Saturation Index (A/CNK) computation with values ranging from 1.40 to 3.06 indicates the pegmatites are peraluminous. Trace and rare-earth elements results show Bakunba location pegmatite is mineralised (Nb: 571.86ppm, Ta: 180ppm) and compare favourably with other mineralised pegmatites in Nigeria; while Ganaja-2 location (Nb: 100.37ppm, Ta: 26.6ppm) are moderately mineralised. Nb-Ta values of Shagari location (33.14ppm; 2.7ppm), Ganaja-1 location (12.6ppm; 3.6ppm) and Crusher location (0.91ppm; 0.2ppm) show they are barren. Various variation plot diagrams, such as Kb/Rb vs Cs, K/Rb vs Rb, also show mineralization status of these pegmatite bodies as compared with some local and foreign pegmatites. Plots of Zr vs SiO2, Rb vs Y+Nb and Rb vs Sr indicate the pegmatites are magmatic, from within plate granites and in crustal thickness of more than 30 km during the time of emplacement.
Ajibade, A.C., Woakes, M., Rahaman, M.A., 1987. Proterozoic crustal development in the Pan African regime of Nigeria, In: Proterozoic lithospheric evolution. American Geophysical Union, Special Publication (Edited by Kroner, A.), pp. 259- 271.
Alfonso, P., Melgarejo, J.C., 2003. Geochemistry of Feldspars and Muscovite in Granitic Pegmatite from the Cape de Creus Field, Catalonia, Spain. The Canadian Mineralogist 41, 103-116.
Black, R., Caby, R., Moussine-Pouchkine, A., Bayer, R., Betrand, J.M., Boullie,r M.M., Fabre, J., Resquer, A., 1979. Evidence for late Precambrian plate tectonics in West Africa. Nature 278, 5701: 223-227.
Condie, K.D., 1976. Trace element geochemistry of Archean granite rocks from the Baberton region, South Africa. Earth Planetary Science Letter 29, 389-410.
Dada, S.S., 1998. Crust-Forming ages and Proterozoic Crustal Evolution of Nigeria: A Reappraisal of Current Interpretations. Precambrian Research 87 (1-2), 65-74.
Dada, S.S., 2006. Proterozoic evolution of Nigeria. In: Oshi O (ed) The basement complex of Nigeria and its mineral resources (A Tribute to Prof. M.A.O. Rahaman), Akin Jinad & Co. Ibadan, pp 29-44.
Egbuniwe, I.G., 1982. Geotectonic evolution of the Maru Belt, NW Nigeria. Unpublished Ph.D. Thesis, University of Wales, Aberystwyth.
Ekwueme, B.N., 2004. Pan-African Schist of Southeastern Nigeria and their relationship with Schists of Cameroon. Book of Abstracts 40th Nigerian Mining and Geosciences Society. International Conference, Maiduguri, 18.
Elueze, A.A., Aromolaran, O.K., 2014. Compositional studies in relation to Ta/Nb enrichment in pegmatites around Ofiki, in Precambrian Basement Complex of southwestern Nigeria. Journal of Mining and Geology 50 (1), 19-29.
Falconer, J.D., 1911. The geology and geography of Northern Nigeria. Macmillan, London, 135pp.
Garba, I., 2003. Geochemical discrimination of newly discovered rare-metal bearing and barren pegmatites in the Pan-African (600 ± 150 Ma) basement of northern Nigeria. Applied Earth Science (Trans. Inst. Min. Metall. B) 112, B287.
Grant, N.K., 1978. Structural distinction between a metasediment-tary cover and an underlying basement in the 600 my old Pan-African domain of Northwestern Nigeria. Geological Society of America Bulletin 89, 50-58.
Grant, N.K., 1970. Geochronology of Precambrian basement rocks from Ibadan, South-Western Nigeria. Earth Planet Science Letters 10, 19-38.
Holt, R.W., 1982. The Geotectonic Evolution of the Anka Belt in the Precambrian Basement Complex of N.W. Nigeria. Unpublished Ph.D. Thesis, The Open University.
Jacobson, R.E.E., Webb, J.S., 1946. The pegmatites of central Nigeria. Geological Survey of Nigeria Bulletin 17, 1-73.
Kuster, D., 1990. Rare-metal pegmatites of Wamba, central Nigeria - their formation in Relationship to late Pan-Africa granites. Mineralium Deposita 25 (1), 25-33.
Matheis, G., 1987. Nigerian rare-metal pegmatites and their lithological framework. Geological Journal 22 (Thematic Issue), 271-291.
Matheis, G., Caen-Vachette, M., 1983. Rb-Sr isotopic study of rare metal bearing and barren pegmatites in the Pan-African reactivation zone of Nigeria. Journal of African Earth Sciences 1, 35-40.
Matheis, G., Emofurieta, W.O., Ohiwerei, S.F., 1982. Trace Element Distribution in Tin-bearing Pegmatites of southwestern Nigeria. In Metallization Associated with Acid Magmatism. A.M. Evans. (ed.) John Wiley & Sons Ltd London. pp. 205-220.
McDonough, W.F., Sun, S., 1995. The Composition of the Earth. Chemical Geology 120, 223-253.
Okunlola, O.A., 2005. Metallogeny of tantalum-niobium mineralization of Precambrian Pegmatites of Nigeria. Mineral Wealth 137, 38- 50.
Okunlola, O.A., Jimba, S., 2006. Compositional trends in relation to Ta-Nb mineralization in Precambrian pegmatites of Aramoko-Ara-Ijero area, southwestern Nigeria. Journal of Mining and Geology 42 (2), 113-126.
Okunlola, O.A., Akintola, A.I., 2008. Compositional features and rare metal (Ta-Nb) potentials of Precambrian pegmatites of Lema-Ndeji area, Central Nigeria. Mineral Wealth 149, 43-53.
Okunlola, O.A., Ocan, O.O., 2009. Rare metal (Ta-Sn-Li-Be) distribution in Precambrian Pegmatites of Keffi area, Central Nigeria. Nature and Science 7 (7), 90-99.
Okunlola, O.A., Somorin, E.B., 2006. Composition features of Precambrian Pegmatites of Itakpe Area, Central Nigeria. Global Journal of Geological Sciences 4 (2), 221-230.
Olayinka, A.I., 1992. Geophysical siting of boreholes in crystalline basement areas of Africa. Journal of African Earth Sciences 14, 197-207.
Olade, M.A., Elueze, A.A., 1979. Petrochemistry of the Ilesha amphibolites and Precambrian crustal evolution in the Pan-African domain of southwestern Nigeria. Precambrian Research, 8, 303-318.
Omada, J.I., Kolawole, M.S., Odoma, A.N., 2015. Field and petrochemical studies of pegmatites in parts of Lokoja, Central Nigeria. Journal of African Earth Sciences 101, 266-273.
Pearce, J.A., Harris, N.B., Tindale, A.G., 1984. Trace Element Discrimination Diagrams for the Tectonic Interpretations of Granitic Rocks. Journal of Petrology 25, 956-983.
Rahaman, M.A., 1981. Recent advances in the study of the basement complex of Nigeria. Abstract, 1st Symposium on the Precambrian Geology of Nigeria.
Rahaman M.A., 1988. Recent Advances in the study of the Basement Complex of Nigeria. In: Oluyide, P. O., Mbonu, W. C., Ogezi, A. E., Egbuniwe, I. G., Ajibade, A. C. and Umeji, A.C., (eds). Precambrian Geology of Nigeria. Geological Survey of Nigeria, 11-43.
Straurov, O.O., Stolyarov, I.S., Iocheva, E.I., 1966. Geochemistry and origin of Verkh – Isetgranitoid massif in central Ural. Geochemistry International 6, 1138-1146.
Trueman, D.L., Cerny, P., 1982. Exploration for rare-metal granitic pegmatites in Cerny, P., ed., Granitic Pegmatites in Science and Industry, Mineralogical Association of Canada, Short Course Handbook, 8, 463-493.
Turner, D.C., 1983. Upper Proterozoic schist belts in the Nigerian sector of the Pan African Province of West Africa. Precambrian Resources 21, pp. 5-79.
Copyright (c) 2021 Daniel Imariabe Omoruyi
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.
The authors keep the copyrights of the published materials with them, but the authors are aggee to give an exclusive license to the publisher that transfers all publishing and commercial exploitation rights to the publisher. The puslisher then shares the content published in this journal under CC BY-NC-ND license.