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Li, Cs, Ta and Rb enrichment in metasedimentary intrusive body: a marker of rare metal potential mineralisation of pegmatite in origin, Musha-Ntunga area, Eastern Province, Rwanda

Author Affiliations

  • 1Institute of Life and Earth Sciences, Pan African University, Ibadan, Nigeria & Department of Geology, University of Ibadan, Ibadan, Nigeria & Department of Mining regulation and Inspection, Rwanda Mines, Petroleum and Gas Board, Kigali, Rwanda
  • 2Department of Geology, University of Ibadan, Ibadan, Nigeria
  • 3Department of Geology, University of Ibadan, Ibadan, Nigeria

Int. Res. J. Earth Sci., Volume 7, Issue (1), Pages 1-12, January,25 (2019)

Abstract

The study aims to geochemically characterize the pegmatite and elucidate the current processes occurred after the primary emplacement of ores in Musha-Ntunga area, Rwanda. The rare metal pegmatites intruded the metasedimentary rocks dominated by schists in Musha formation. The laboratory analyses of petrography and geochemistry were used. The petrographic analysis investigated mineral assemblages, and whole rock analysis for major elements by ICP AES and trace elements by ICP MS. Petrographic studies revealed the mineral assemblages include plagioclase, mica, tourmaline and muscovite. The results of geochemical analysis revealed medium to high silica content (in wt%) ranges from 67.08-70.66, the Al2O3 ranges 26.6-28.7 (in wt%), Na2O ~0.06 (in wt%) and CaO varies between (0.06-0.07) (in wt%) for the intrusive body of pegmatite in origin intruded metasedimentary rocks. These alterated intrusion of pegmatite in origin are enriched in trace elements of Rb(~715.18ppm ), Cs( ~34.43ppm), Li(~148.33ppm), W(~492.ppm), and the rare metals Nb(1154.16ppm~), Ta(>2500 ppm), and Sn(>10.000 ppm), the enrichment of those elements has commonly indicated a marker of a magmatic-hydrothermal alteration of pegmatite intrusion. The molar Na2O-Al2O3-K2O plot revealed that the pegmatites evolved from the peraluminous granite (or S-type). REE abundance in whole rock pegmatitic intrusive body was &

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