Base metal-enriched gold-quartz veins in the eastern Cameroon goldfields, West-Central Africa

Abstract

The Colomine and Bétaré Oya gold districts are among the main gold-producing districts in the reworked Paleoproterozoic terrain of eastern Cameroon. The characteristics of the mineralized and barren veins from these areas were investigated with the aim of helping artisanal gold miners and Small and Medium Size Enterprises (SME) active in the region to identify new gold targets. This could help boost the country's annual gold production and also generate local revenue for the indigenous community. Gold mineralization occurs in gently dipping NNE-SSW to NE-SW-trending quartz veins hosted by hydrothermally altered granitic rocks in the Colomine gold district and weathered mica schist in the Bétaré Oya gold district. The hydrothermally altered granite wallrock hosts millimetric-sized quartz lamellae/veinlets characterised by a quartz-sericite-muscovite-biotite±chlorite±albite assemblage. The mineralized quartz veins in both districts are fractured, brecciated, sheared, and vuggy, characterised by a quartz±gold±sulphide±hematite±limonite±goethite ±carbonate assemblage. Hematite occurs in a botryoidal form, ind icating the strong influence of supergene processes. This alteration phase is associated with supergene gold enrichment in the veins and constitutes the most attractive part to be exploited by artisanal and SMEs. The barren veins trend NW-SW to N-S and are generally massive to foliated. Gold ranges between 5 and 32 ppb in the wall-rock and up to 2070 and 4600 ppb in hematite-bearing quartz veins. Bulk geochemistry reveals Au-Mo (±Ag) element association in Colomine and Au-Ag-Mo-Cu in Bétaré Oya indicative of a sulfide-bearing granitic source.

Heavy Metal Contamination and Ecological Risk Assessment in Soils of the Pawara Gold Mining Area, Eastern Cameroon

“…Refs. [69,70,[80][81][82][83], which were crosscut by D 4 brittle structures. Thus, splays of shear and fault zones [80] crosscut the host rocks, creating fluid paths for hydrothermal activities and subsequently mechanical and chemical weathering [27,84].…”

“…Galena is the main ore mineral for Pb, sphalerite for Zn and Cd and chalcopyrite for Cu and Fe. These mineral assemblages alongside quartz are often precipitated by hydrothermal fluids within faults, fracture and foliation planes to form veins, lodes and pegmatites during gold mineralization as observed in the Betaré-Oya and Batouri gold districts [27,81,83,85]. Weathering of these minerals eventually releases Zn, Cd, Cu, Fe, Mn and Pb into the environment especially when exposed to mine tailing, thereby accounting for their high levels in the soils.…”

Tourmaline occurrence and gold mineralization at a granitoid-metasediment contact in the Upper Lom Basin, east Cameroon

“…Orogenic primary gold mineralization is suggested in the southern goldfield of Cameroon [21,[37][38][39], based on placer gold studies. Hydrothermal quartz vein style of mineralization is common in the eastern and northern gold terrane as the possible primary source of gold [21,22,34,40]. In order to enhance the understanding of the style of primary gold mineralization in eastern Cameroon inferred from residual gold microchemistry, there is need to also evaluate wallrock mineralogy such as tourmaline in combination with associated gold composition.…”