Geochemical Features And Rare - Metal (Ta-Nb) Potentials Of Precambrian Pegmatites Of Sepeteri Area, South Western Nigeria

Abstract

Geochemical analysis of twenty-five muscovites extracts sampled from pegmatites of Sepeteri area was carried out using Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-­AES) analytical method. Results indicate they are generally highly siliceous (SiO2, 54.05-77.64%) while Al2O3 content ranges from 14.18-31.37%., with an average of 66.17 and 25.51 respectively. Fe2O3, TiO2, P2O5 are generally low (less than 3.00 %). The samples are fairly enriched in Rb, Ba, Sr, Zr but comparatively poor in the rare metals Ta, Nb, W and Sn. Cs values are also usually less than 90 ppm. Be is also marginally low (6-49 ppm) while Na/K ratio are slightly less than 1.0 indicating some degree of albitization. The degree of albitization is further revealed by the Ti-Sn (Nb+ Ta) discriminant diagram with sample plotting in the zone of albitization. Plots of K/Rb against Rb; K/Rb against Cs; and Ta against Ga indicate marginal to low level of rare metal mineralisation.
Geochemical potentials of Ta - mineralization is also revealed by Ta against Cs discriminant plot with most of the pegmatites samples plotting in the central area of the data field, thus showing similarities to those of Noumas, Central claims, Silverleaf, and Odd west deposits which are known to contain fairly low level of Ta mineralization endowments.


IFE Journal of Science Vol. 9 (2) 2007 pp. 203-214