Assessment of Banded Iron Formations around Gouap Area as Potential High-Grade Iron Ore (Nyong Serie, Congo Craton - South Cameroon)

Abstract

The Gouap area is found in the southern part of Cameroon and belongs to the Nyong Series situated NW corner of the Ntem Complex. The assessment of banded iron formations (BIFs) in this area is carried out through rock sampling survey. Samples were analyzed by inductively coupled plasma mass spectrometry (ICP-MS) combined with instrumental neutron activation analysis (INAA) technologies to completely characterize the rocks. The studied banded iron formations show microband texture and granoblastic microstructure. The mineral assemblage indicates that they undergone the metamorphism of greenschist facies conditions. The chemical composition of the Gouap iron formations shows that the major components (99.43%) that are Fe 2 O 3 and SiO 2 indicate the purity of the chemical precipitates . The Gouap iron deposits fall into the group of oxide facies with magnetite as dominant mineral and the most diagnostic fingerprints of the source metals are Ni, Cr and Cu. The Gouap iron deposit displays some light terrigenous input in its geochemistry implying that it belongs to the Algoma- type and indicates that iron formations were deposited in an environment devoid of siliciclastic detrital input. The Gouap BIFs derived from Precambrian mature quartz arenite and Fe-sand that were deposited in an Oceanic Island-arc Margin (ARC) setting under oxic conditions with slow sedimentation accompanied with minor input of anoxic conditions with fast sedimentation. This constitutes a new result for de iron deposits in Cameroon. The overall data of Gouap iron deposits pointing to hydrothermal and Red Sea hydrothermal deposits (RS). They exhibit Low- temperature hydrothermal fluids (< 0.1%) and Seawater, indicating that mixing of seawater and less amount (< 0.1%) of low-temperature hydrothermal fluids (< 200°C) might have occurred during their deposition. Some samples have values that reflect between 1 to 5% of a high-temperature hydrothermal fluid input suggesting that the Gouap iron formations were deposited close to the distal position. The high concentration of Fe 2 O 3(T) in the Gouap iron deposit (average = 63.73 wt%) shows that it has a very interesting potential for exploitation and this iron contents can be classified as high- grade or medium- grade iron ores by global standards, and it fall within the acceptable levels for commercial ores. Gouap BIFs host high- grade siliceous ore with magnetite being the predominant mineral. This also constitutes a new result for the iron deposit in Cameroon.