The Geology and Geochemistry of Kakafu Pegmatites: An Investigation for Lithium Ore Bearing Minerals (Lepidolite-Spodumene), Pategi North Central Nigeria

Abstract

The preliminary investigation of the Kakafu pegmatites was conducted, with the aim of carrying out detail geological mapping and geochemical analysis to reveal common field and geochemical features that will lead to understanding the nature of the Kakafu pegmatites, for the purposes of identifying its lithium minerals potential. Geological mapping reveals three lithological units in the area, which includes; muscovite schist, biotite granite and pegmatite veins. Mineral composition observed in the field and as hand specimen are quartz, plagioclase and orthoclase feldspars, muscovite, biotite and tourmaline. Also the two lithium minerals recognized by the investigation; lepidolite and spodumene (kunzite) grades vertically with depth and along the veins in areas where the veins swells. The main lineament features (fractures, joints and folds) observed trends in the NE-SW, NW-SE, N-S and E-W directions, these directions correspond with orientations of the pegmatites in the study area. Geochemical plots of K vs Rb; K/Rb vs Rb; Li2O vs SiO2 and Ca O vs SiO2 show linkages amongst the pegmatites of the study area. Also the plots of A/CNK vs SiO2 and TiO2 vs SiO2 show all the pegmatites samples fall in the fields of S-type and igneous protolith respectively. These linkages amongst the Kakafu pegmatites suggest they are genetically related to one another, and have same origin (igneous protolith). In terms of mineral potential assessment, the plots of A/CNK vs SiO2; Li2O vs SiO2 and REE show that the Kakafu pegmaites are strongly peraluminous and hence potential for lithium ore mineralization. Furthermore, the concentrations of Li2O of Kakafu pegmatites ranges between (0.82-2.27wt%) and averagely all are above 1wt%. This suggests the Kakafu pegmatites to be moderately potential for lithium ore mineralization.