A preliminary description of the Nigerian lead-zinc field

The lead-zinc deposits of Nigeria occur, with few exceptions, in the main belt of lower Cretaceous formations in the Benue and Niger river region. They constitute mineralized fracture fillings in folded and faulted Aptian to Turonian strata, are closely associated with and probably genetically related to dioritic intrusions emplaced prior to the end of the Turonian, and are classed as hydrothermal deposits formed under mesothermal conditions. Alteration in the zone of oxidation is extensive, resulting in destruction of the primary vein structure, removal of much of the sphalerite by leaching, and formation of lead carbonates and oxides. No evidence of supergene sulfide enrichment was seen.