Characterization of heavy minerals and stream sediment from Bidjouka area, Nyong Complex south Cameroon: implications for gold mineralization

Abstract

The stream sediment geochemistry has a wide application in mineral exploration. In this study, we applied the stream sediment geochemistry to decipher the primary source of gold mineralization, determine the mineralogy of heavy mineral concentrate and also to ascertain the provenance, depositional environment, intensity of weathering as well as determine the tectonic setting. To investigate heavy mineral in stream channel, 20 placer materials from Bidjouka area were assessed by thin plate using polarized microscope. The powder was further characterized by ICP-MS using aqua regia. Results show that placers displayed minerals such as magnetite, zircon and gold. Majors geochemical base metal point out low grade of iron (< 5 wt.%), titanium (< 1.05 wt.%) and alumina (< 0.60 wt.%). The following metallic trace elements used for industrial technology are identified in the samples. It mainly concerns manganese and thorium with content less than 328 and 200 ppm respectively as well as mercury (< 550 ppb). Precious metals are also present in the chemical composition of Bidjouka sediments. The main substances identified is gold with the grade above 2 g/tone, which is an important target in mining exploration. Also the mean value of rare earth elements varying between 1256.6 and 3626.8 ppm are so speculative, with negative and positive Eu and Ce anomaly respectively. Gold is bound with sulfide mineral (Au-Bi), suggesting a sulfidation event during sediments deposition. Factor 4 (Co, Mn, Sc, Au, Bi) refers to the mineralization factor and Co, Mn, Sc, Bi serve as pathfinder of gold. Sediments were deposited under humid, oxic and oxidizing conditions; intermediate intensity of weathering processes of the source rocks had prevailed during deposition, and sediments were rich in plagioclase. These continental sediments have quartzose sedimentary provenance, they were originated from metamorphic sources and were deposited in an active continental margin. The results of this study serve as guide for gold exploration and exploitation in the Bidjouka area.