Petrology and Mining Potential of the Niki-Niki Basic to Ultrabasic Massif in Togo, West Africa

The Niki-Niki massif, located in the central part of Togo, belongs to the suture zone of the Pan-African Dahomeyide belt. The aim of this study is to carry out a petrostructural and geochemical investigation of this massif to characterize its associated mining potential. The methodology implemented is based on a summary of previous works, geological mapping, petrographic study of 20 thin sections, geochemical study through discrimination diagrams of 5 rocks samples, and a soil study of a toposequence. The results show that the Niki-Niki massif is composed of garnet-free granulites, pyroxenites and talcschists. Granulites and pyroxenites generally contain plagioclase, clinopyroxene, orthopyroxene and hornblende. Talcschists contain talc, serpentine and chlorite. These parageneses reflect a metamorphic evolution from granulitization to retrograde metamorphism in the amphibolite to green schist facies. Geochemical data show that the rocks of the Niki-Niki massif are metaluminous. They are characterized by enrichment in LREE element relative to HREE elements and display tholeiitic affinity, with negative anomalies in Nb-Ta and Zr. These characteristics suggest a subduction zone magmatism origin. The features are consistent with protoliths of tholeiites, N-MORB and volcanic arc basalts affinities. The Niki-Niki massif rocks were emplaced in an oceanic environment and likely originated from a metasomatized mantle. They offer significant potential for Ni, Cr, Co, V, Cu, Mo and gold (Au) mineralization. These values present a promising target for exploration of these mineral deposits.