A comparative assessment of Lepidolite-bearing pegmatites from Akpet and Betem areas, Southeastern Nigeria: insights from their geochemical signatures and economic potential

Abstract

Late Proterozoic (Pan-African) pegmatites in Nigeria play host to the mineralization of lepidolite-bearing minerals such as lithium, beryl, tantalum, tourmaline, and gemstones, making it an essential resource for positioning Nigeria as a significant global pointer in solid mineral and renewable energy. This research focuses on the comparative assessment of the geochemical, and mineralogical characterization of the Lepidolite-bearing pegmatites in Akpet and Betem areas, in Cross River State, Southeastern Nigeria. Twenty samples (ten from each location) were systematically collected and analyzed using inductively coupled plasma mass spectrometry. The data were further processed using different fractional indices and multivariate statistics. SiO₂ recorded the highest concentration across the two locations ranging from 48.14 to 99.79% with a mean of 80.66% and 70.1 to 98.3 with a mean of 82.080%wt for Akpet and Betem area respectively. SiO₂, Al₂O₃, K₂O, and Na₂O were high while CaO, MnO, MgO, and TiO₂ were low in pegmatites from both areas. Trace element and rare earth element analysis revealed high concentrations of Co (78%), Rb (4%), Cu (2%), Ni (2%), and Zn (2%) in Akpet pegmatites, while Betem pegmatites were highly enriched in Rb (23%), Ba (21%), Zn (21%), and Co (13%). Results from the protolith discriminant plots of SiO₂ vs. Na₂O+K₂O-CaO and SiO₂ vs. K₂O indicate that the Akpet pegmatites exhibit a more diverse origin, possibly involving input from igneous protoliths. The discrimination plots of K/Rb vs. Rb and Ta vs. K/Cs reveal that the pegmatites from both areas were highly mineralized concerning Tantalite and Rubidium but barren to beryllium.