Study of Origin, Geology and Geochemical Classification of the Granitoids of Imori Area, North Central Nigeria
DOI:
https://doi.org/10.31695/IJERAT.2022.8.3.3Keywords:
Pan-Africa calc-alkaline granite, Mesozoic alkali granite, Ferromagnesian minerals, Sialic materials, Co-magmaticAbstract
Two distinct generations of granitiods in terms of space and time were identified in the Imori fields of north-central Nigeria. The first generation is the Older Pan-Africa calc-alkaline granite suites (OPACG) which comprise the migmatite-gneiss and the porphyritic hornblende-biotite granite. The second group is the Younger Mesozoic alkali granite suites (YMAG). This comprises rhyolite, biotite granite, and arfvedsonite granite. The OPACG suites are characterized by depletion in SiO2 ranging from 63.30 wt % - 68.38 wt % as compared to the YMAG suites which range from 70.41 wt % - 79.14 wt %. In addition, the OPACG suites are characterized by higher concentrations of MgO, fe2O3, Al2O3, TiO2, CaO, and Sr as compared to the YMAG suites. The YMAG suites are characterized by an excess of total alkaloids (Na2O +K2O), Cr, Nb, W, Ta, and lower concentrations of ferromagnesian minerals. These characteristic indicates that the OPACG suites are generated from deep-seated crustal levels rocks with the possibility of mantle materials. The YMAG suites were originated from partial melting of crustal sialic materials. Both the trace element patterns of the OPACG suites and the YMAG suites indicate that each suite is co-magmatic.
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