Petrography and Petrochemical Characteristics of Rare Metal Pegmatites around Oro, Southwestern Nigeria

Abstract

Petrographic and geochemical evaluation of pegmatite bodies occurring as discontinuous dykes have been studied in Oro area of southwestern Nigeria, with a view to determine the compositional characteristics that may be related to Ta-Nb mineralization potentials. They are found intruding semi discordantly, the older assemblages of quartz mica schist and granite gneiss. A total of twenty-eight samples comprising whole rock pegmatites and eluvial soils were analyzed for major, trace and rare earth elements using (ICP-AES) geochemical method which show the pegmatite samples to be generally highly siliceous with SiO2 values ranging from (71.49-97.77%) with an average of 86.43% in the whole rock samples, and it also ranges from (41.88-57.99%) with an average of 48.43% in the eluvial soil samples, while Al2O3 content is as high as 25.87% in the eluvial soil samples and 6.86% in the whole rock samples depicting the complexity of the pegmatite rock. Variation plots of K/Rb versus Rb, Ta versus Rb, Ta versus Nb, Ta versus K/Cs, Ta versus Cs+Rb and Ta versus Cs discriminant plot indicate the potentials of rare metal mineralization.