West African Craton
[1] Cratons themselves are tectonically inactive, but can occur near active margins,[2] with the WAC extending across 14 countries in Western Africa, coming together in the late Precambrian and early Palaeozoic eras to form the African continent.
It consists of two Archean centers juxtaposed against multiple Paleoproterozoic domains made of greenstone belts, sedimentary basins, regional granitoid-tonalite-trondhjemite-granodiorite (TTG) plutons, and large shear zones.
[4] The WAC stretches from the Little Atlas mountains of Morocco to the Gulf of Guinea, and is bounded by mobile belts of much younger rocks to the north, east and west.
A definitive evolution of the area has not been determined as a result of conflicting interpretation of the relationship between low-grade greenstone belts and high-grade gneissic terranes dominated by TTG suites.
The lithosphere is broken up into tectonic plates, which slowly move in relation to one another at speeds of 50–100 mm annually, colliding, combining into continents, splitting and drifting apart to form new continental configurations.
[19][20] South of the mountains, the West African Craton is relatively flat, mostly desert or dry savanna apart from the areas near the Atlantic or Gulf of Guinea.
Low temperature thermochronology data indicates that the western side of the shield has an igneous differentiation post-Triassic thermal history, largely controlled by vertical movements of the crust via burial and exhumation processes.
[7] The southern Man shield covers the countries Ivory Coast, Mali, Burkina Faso, Ghana, Sierra Leone, Liberia, and Guinea.
[6] Within the West African Craton, there is a large amount of mining activity covering resources such as gold, copper, cobalt, silver, tin, and zinc.
[24] Artisanal mining activity in the craton dates back to the early 1960s which used quartz vein debris as a gold indicator.
[6] In 1985 the State of Burkina Faso created an official structure, known as Le Projet Orpaillage, for the management of gold mining and buying in the region.
Metallurgical studies on the gold panning rejects were funded by the United Nations Development Programme (UNDP) and the Bureau de Recherches Géologiques et Minières (BUMIGEB).
The treatment of mine tailings collected from artisanal working gold was the principle operation conducted by the Compagnie d'Exploitation des Mines d'Or du Burkina (CEMOB), operating a heap leach plant which processed approximately 500 tonnes of gold panning rejects per day.
Quarrying and mining provides a livelihood for greater than 250 thousand people in Sierra Leone alone, employing approximately 15% of its population, producing a significant amount of material to qualify as a resource-rich country.
