Geology and Geochemistry of the Sub-Basalt Tin Mineralization in Wereng, Riyom, Part of the Naraguta SE Sheet 168

Abstract

The study area is situated within the Jos-Bukuru Younger Granite Complex and, and 
overlies the Basement Complex of North Central Nigeria. It is bounded between 
latitudes 8º 41’ 00’’N - 8º 50’ 00’’ and Longitudes 9º30’ 00’’ - 9º 40’ 00’’E which is 
part of the Naraguta SE Sheet 168. Detailed studies shows how the widespread 
Tertiary-Quaternary Basaltic Lava flow that earlier submerged concentrated Tin 
deposits along ancient river/stream channels have suffered great deal of chemical 
alteration (continuous oxidation an d leaching), thereby resulting into various 
grades of Basaltic saprolite bands/layers of varying thicknesses within the study 
area whose boundaries are geochemically controlled and not lithological, they 
include; the Iron Caps atop, the reddish-brown saprolite layer, the reddiSub
Basaltsh-brown+intercalations of Kaolin layer, the yellow saprolite layer, and finally 
the Kaolin layer which directly overlies the Tin bearing sediment layer along ancient 
river/stream beds. The saprolite laterite constitute an overburden thickness of 35
40m to the (2-2.5m thick) Tin deposit bearing sediments. Geochemical and 
petrographic investigation reveals that the mineralized greisens of Biotite (Tin) 
Granite and the Basement rock (Gneiss) are petrogenetic to the origin of the Tin 
deposits concentrated within the ancient river/stream beds. This studies also shows 
the prolificness of the Sub-Basalt Tin mineralization of (40,000-62,000ppm per 
every 1.5kg of sediments sampled) within the area, as well as Zircon, Kaolin and 
Niobium. Integrating information from concentration trend of Tin obtained from Pit 
samples, aeromagnetic data which shows the heavy metals concentration trend of 
the study area, and a careful studies of modern drainage patterns gives a NE-SW 
orientation pattern which suggests the paleo/ancient river/stream direction, 
serving as a very useful exploration tool of utmost importance. Occurrences of 
Nodular Basalts in dyke form which have remained stable and unaltered throughout 
the study area.