Petrography and Geochemical Studies of Eyingba Lead-zinc Mineralization, Lower Benue Trough

Abstract

The geochemical studies of the Enyingba lead-zinc mineralization in the Lower Benue Trough was carried out to unravel the elemental association of the mineralization along with the gangue minerals and to further define the provenance of the mineralization. The petrographic studies of galena, sphalerite, chalcopyrite, siderite was carried out with Carborundum grit of 90, 120, 400, 600, 800, 1000, 1200 and magnesium oxide (MgO) to ensure smoothening of samples on a polishing machine. The geochemical result obtained indicated the enrichments of Pb (400000ppm) in galena, Zn (200000ppm) in sphalerite, Cu (100000ppm) for chalcopyrite. Chondrite normalization for galena/barite/siderite plots reveals positive Eu and Tm anomalies in galena, with a gentle slope depletion from the LREEs to HREEs. Chalcopyrite/sphalerite normalization plots also indicated a positive spike for Eu and Tm which imply that they are co-genetic. The concentrations of these elements in their ores reveal their abundance, high grade and could be exploited in large scale. Exsolution blebs from polished section also emphasize paragenetic relationship. The positive anomalies observed on the chondrite plots are due to hydrothermal fluid inputs in the mineralization since REEs are believed to be the least soluble and relatively immobile during weathering and hydrothermal alterations.