Geochemical discrimination of Pegmatites around Tafawa Balewa

Abstract

Pegmatite exposures around Tafawa Balewa occur in swarms spamming several 
meters with individual veins limited to 2m width. Field characteristics include the 
absence of zonation and metasomatic aureole as in Magalam or a characteristic 
local zonation and more versatile mineralogy and metasomatic zone often lined 
with euhedral crystals of Schorl as in Gikil. The pegmatites also show variations in 
their chemistry notably in the composition of SiO2, Al2O2 and TiO2. Variation 
diagrams of Rb vs Ba Vs Sr, K/Rb vs Rb and K/Rb vs Cs of whole rock samples indicate 
that the pegmatite of Gikil is highly fractionated, bear strong rare metal affinity and 
variably enriched in Cs, Ta and Be and belong to the LCT- Tourmaline subtype class 
of rare metal pegmatites. They are significantly mineralized in LiO2 (up to 2.4%), Ta 
and Beryl. All pegmatites were granitic and probably share a similar melt source. 
The pegmatites around Gikil are post-orogenic, postdating the possible syn- 
orogenic pegmatites of Magalam.