Author(s)

Noël Watha-Ndoudy^1,2, Prince Espoire Wamene Okoumel¹, Timothée Miyouna¹, Renaud Hermann Assouka Mpika³, Eddy Guembou Massala³, Guichel Souaty Mibantsa³, Kester Mayenga³, Joseph Victor Hell⁴, Boniface Kankeu⁴, Florent Boudzoumou¹

¹Laboratory of Geosciences, Faculty of Science and Technology, Marien Ngouabi University, Brazzaville, Congo.
²National Institute of Forestry Research (IRF), Brazzaville, Congo.
³Gold Mines and Quarries of Congo, MAC-CONGO, Brazzaville, Congo.
⁴Institute of Geological and Mining Research (IRGM), Yaoundé, Cameroun.

The Elogo region has been subjected to craft industry and semi-industrial mining for gold-bearing placers, since the colonial times. It is actually undergoing an intensive exploration for a primary gold deposit. The goal of this study is to contribute to the exploration of the primary gold deposit in the Elogo Region (North-West of Congo Republic). The methodology consisted of characterization of placers deposits by their lithology, mineralogy and the gold grains shape, in order to constrain the source of gold with the respect to the local geology. The results obtained show that alluviums are polygenic and yields seventeen mineral species composed of zircon, olivine, magnetite, ilmenite, gold, garnet, rutile, coltan, cassiterite, monazite, apatite, amphibole, tourmaline, pyrite, limonite, chromite, and amphibole. The morphoscopy of gold grain shows single grains and grains with quartz inclusions that suggest their relationship with quartz veins. The gold grains are flattened, sub-flattened, and rounded. The northern region of Elogo characterized by a dominance of coarser quartz-included gold grains indicates a proximal proparte origin (less than 50 m), while the southern region, showing less coarse and more evolved grains with choc marks, appears to be associated with a distal pro-parte origin (more than 300 m). The multivariate statistical analysis shows seven classes of samples corresponding to the mineralogical paragenesis suggesting various sources, consisting of high-grade metamorphic, granitoids, pegmatites, basic and ultrabasic rocks, and BIFs that provided minerals to the placers. Gold mainly comes from hydrothermal quartz veins and probably from the peptization of gold from the weathering of sulfides occurring in the BIF. In the Elogo region, gold exploration for primary deposits should look for and follow the hydrothermal system developed in this region. Chemical analysis for the gold grains and associated minerals is necessary to better guide the proposed geochemical prospecting.

Auriferous Placers, Associated Minerals, Correspondence Factor Analysis, Principal Component Analysis, Elogo, Gold Exploration

Watha-Ndoudy, N. , Okoumel, P. , Miyouna, T. , Mpika, R. , Massala, E. , Mibantsa, G. , Mayenga, K. , Hell, J. , Kankeu, B. and Boudzoumou, F. (2023) Characterization of Gold Bearing Placers and Associated Minerals in the Elogo Region (North-West Congo Republic). Open Journal of Geology, 13, 287-305. doi: 10.4236/ojg.2023.135014.