Abstract
The study was carried out to determine the rare metal mineralization potential of some pegmatites associated with metasediments in the Igangan 240 NW sheet. Geological mapping on a scale of 1:50,000 revealed the pegmatites intrude metasediments and geochemical analysis for major, trace and rare earth elements were carried out using ICP MS/AES. Petrographic studies reveal a mineral assemblage of quartz, microcline and tourmaline; SEM studies revealed garnet and tourmaline to be close to the spessartine end-member and schorl respectively with albite occurring as the dominant plagioclase feldspar in the pegmatites. Result of geochemical analysis revealed SiO2 with an average of 73.91% in the whole rock pegmatite Al2O3 with an average of 13.93%, and average concentration of 0.57%, 4.3% and 4.77% for CaO, Na2O and K2O respectively. It also revealed average concentration of 29 ppm, 153 ppm, 30 ppm, 118 ppm and 129 ppm for W, Li, Ta, Nb and Sn in the mica respectively which is above the average values in the whole rock, felspars and tourmaline extracts. REE abundance in the whole rock pegmatites is low to moderate with ∑REE varying between 8 - 220 ppm, 2 - 23 ppm in feldspars and 3 - 32 ppm in mica signifying no form of REE enrichment. Geochemical analysis results and trace elemental plots such as K/Rb vs. Rb, Ta vs. Ga, Ta vs. Cs were used to assess rare metal mineralization and it revealed the pegmatites have low level of rare metal and rare earth element mineralization with average k/Rb values of 177 indicative of low fractionation levels in the pegmatites.
Highlights
Pegmatites are economically important sources of ceramic materials and high technology metals such as Rb, Cs, Be and the high field strength elements [1]
The study was carried out to determine the rare metal mineralization potential of some pegmatites associated with metasediments in the Igangan 240 NW sheet
They are associated with Nb-Ta-Sn-W mineralisation and the petrogenesis of pegmatites can be studied from the feldspar, mica and tourmaline which are sensitive indicators of magmatic and post magmatic events responsible for pegmatite evolution [3]
Summary
Pegmatites are economically important sources of ceramic materials and high technology metals such as Rb, Cs, Be and the high field strength elements [1]. Granitic pegmatites are an important part of granitic intrusions in orogenic belts and are characterized by strong enrichment in incompatible elements such as Rb, Cs, Li, Be and Sn. Granitic pegmatites are an important part of granitic intrusions in orogenic belts and are characterized by strong enrichment in incompatible elements such as Rb, Cs, Li, Be and Sn They are associated with Nb-Ta-Sn-W mineralisation and the petrogenesis of pegmatites can be studied from the feldspar, mica and tourmaline which are sensitive indicators of magmatic and post magmatic events responsible for pegmatite evolution [3]. Various studies have been carried out on pegmatites in Nigeria by [4] [5] [6]. In the southwestern part of Nigeria, pegmatites are hosted within varieties of rocks of metamorphic and igneous origin where they intrude the older lithologies discordantly [7] [8] [9] [10] but there is paucity of information on pegmatites in Igangan sheet 240 NW
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