Petrogenetic characterization of banded iron formations of the Nyong Complex, Southern Cameroon: implications for the origin and depositional setting of Paleoproterozoic Iron Formations

Field mapping was carried out in the Bidjouka area and representative banded iron formation (BIF) samples analyzed using ICP-MS and INAA techniques. The objective of this work was to characterize the BIFs and constrain their petrogenesis, origin, evolution and depositional setting. BIFs display microband and mesoband texture, granoblastic microstructures, and are composed of biotite, quartz, and magnetite/hematite. They show 41.86-56.49 wt.% Fe2O3 and 39.81-49.51 wt.% SiO2 characterizing oxide facies BIFs. The deposit shows weakly negative Eu anomaly (Eu/Eu* = 0.66-0.87) implying the signature of hydrothermal fluids (< 0.1%). BIFs have a chemogenic nature, formed in the Precambrian under different oceanic chemical conditions, and less affected by continental crustal sediments. Fe was derived from hydrothermal fluids released into the deep-ocean and the depositional site was more distal. This is a low-grade siliceous BIF, acceptable for commercial iron ores. The Bidjouka BIF deposit is mostly similar with Paleoproterozoic global BIF of Superior-type. Keywords- Bidjouka, Microband and mesoband, Chemogenic, Low-grade, Low-T hydrothermal.