Lithium, Rare-Metal and Gemstone Potential of the Pegmatites in Arikpa, North-Central Nigeria

Abstract

Lithium-Caesium-Tantalum (LCT) pegmatites of the Nigerian Basement Complex are increasingly targeted for their rare-metal potential, yet the geochemical and petrogenetic characteristics of many occurrences, including the Arikpa pegmatites of Nasarawa State, remain undocumented. This study presents major-oxide, trace-element, and rare-earth-element (REE) geochemistry of pegmatites and associated host rocks from Arikpa, North-Central Nigeria, obtained by X-ray fluorescence (XRF) analysis of eleven pegmatite samples and nine host-rock samples, integrated with petrogenetic and tectonic discrimination diagrams. SiO₂ contents range from 51–74 wt%, with systematic negative correlations of MgO, Fe₂O₃, CaO, TiO₂, and P₂O₅ against SiO₂, indicating progressive fractional crystallisation. A/NK–A/CNK and A/CNK–SiO₂ plots classify the pegmatites as predominantly metaluminous to peraluminous I-type granitic melts, while R₁–R₂ tectonic discrimination places the suite within late- to post-orogenic fields consistent with emplacement during the waning stages of the Pan-African orogeny. Trace-element data show strong enrichment of large-ion lithophile elements (K, Rb, Ba) with pronounced negative Nb-Ta-Ti anomalies, and K/Rb–Rb and Zn/Sn–K/Rb relationships indicate a genetically related pegmatite suite showing progressive Sn enrichment with increasing fractionation. Li₂O concentrations range from 0.18–0.50 wt%, averaging below 1 wt%, indicating that the Arikpa pegmatites are only moderately fractionated with respect to lithium and are not currently prospective as a standalone lithium resource, although they show moderate potential for Sn-Li-Rb multi-metal mineralization. Comparison with the Wamba, Nasarawa, Keffi, and Janjala pegmatite fields places Arikpa within the regional LCT pegmatite province of Central Nigeria.