Geochemical Characterization of a Stratigraphic Log Bearing Iron Ore in the Sanaga Prospect, Upper Nyong Unit of Ntem Complex, Cameroon

Abstract

The Sanaga prospect in the north of Edea is located in the upper Nyong unit of the Ntem complex in Cameroon. The objective of this study is to use geochemical data trends for major and some trace elements to constrain the origin and/or sources of various constituents in the iron-bearing units as well as assess their economic potentials. The rock samples were collected from a single drill core sampled at various depths. Major elements were analysed using X-ray fluorescence spectrometry after powder digestion following. All data were processed with the aid of XLSTAT. The stratigraphic log described revealed from top to bottom two lithological sequences composed of oxidized formations (oxidized cap and oxidized gneiss), and gneissic formations (magnetite gneiss, magnetite amphibolite gneiss and enriched magnetite amphibolite gneiss successions). Detailed examination showed that quartz and iron oxides are the main minerals present. Bulk geochemical analysis of the oxidized and gneissic formations showed that Fe2O3 and SiO2 are the main constituents (averaging 84.40 wt % and 92.54 wt %, respectively), confirming that quartz and iron oxides are the major mineral phases in both the oxidised and gneissic formations. Al2O3 averages 9.34 wt % and 3.06 wt %, Na2O averages 0.04 wt % and 0.59 wt %, K2O averages 0.26 and 0.53 wt %, and P2O5 0.07 and 0.05 wt %, respectively, in both oxidized and gneissic formations. Concentrations of trace elements in the various lithologies are generally very low (2O3 with LOI (r > 0.8), and Zr (r > 0.7); LOI with Zr (r > 0.8). From these data it appears that mineralisation at the Sanaga prospect is restricted to the magnetite gneiss. The high concentration of Al2O3 (average 9.34 wt %) in the oxidized iron formations is partially due to its introduction during recent chemical weathering. The Sanaga iron formations are metamorphosed chemical sediments formed by precipitation of iron and silica from a mixture of seawater and hydrothermal fluids with a significant terrigenous input.