West African Goldfields

Abstract

The West African region has long been known for its gold endowment and gold production. Apart from the last 20 to 30 years, this production was largely derived from informal artisanal workings covering large areas of West Africa. For a period of over a thousand years until 1500 AD, West Africa was the world's most important supplier of gold, much of which formed part of the trans-Sahara trade with the Arab world, whose monetary system was based on gold. Artisanal gold mining is still widespread across West Africa and a significant number of modern gold mines in the region were founded on artisanal mining sites. Aided by regional mapping and geochemical programmes by geological surveys and the UNDP, as well as the dramatic rise in the gold price between 2001 and 2011, the West African region has seen a rapid expansion in gold exploration activity over the last two decades. This resulted in the establishment of new mines in Mali, Burkina Faso, Cote d'Ivoire, Ghana, Senegal and Guinea. The West African Craton is composed of Archaean and Palaeoproterozoic rocks which are generally poorly exposed due to deep weathering. While gold mineralisation is known in the Archaean, most gold deposits and occurrences in the region are hosted in a wide range of rock types, from volcanic to turbiditic metasedimentary sequences, which form part of the Palaeoproterozoic Birimian Supergroup. The majority of deposits are of orogenic-type, however gold also occurs in intrusion-related deposits, skarn deposits and as palaeoplacer deposits. Large parts of the West African region remain underexplored relative to similar gold provinces elsewhere. Apart from the Kibali deposit in the northeastern Democratic Republic of Congo (DRC), the West African region leads the continent in terms of recent gold exploration focus and discovery, and the region is still considered largely prospective and relatively immature from an exploration perspective.