Introduction to Côte d’Ivoire
The Republic of Ivory Coast is located in West Africa on the Gulf of Guinea and shares borders with Liberia and Guinea to the West, Mali and Burkina Faso to the north and Ghana to the East. Ivory Coast has a total land area of approximately 322,462 square kilometres which is equivalent to approximately 60% of the size of France. In 2009, the total population of the country was estimated at 20.7 million most of whom are French-speaking.
Ivory Coast gained its independence from France on the 7th of August 1960. Yamoussoukro was appointed the Administrative Capital of the country in 1983 and is located in the southern central portion of Ivory Coast. The city of Abidjan, located in the south east of the country, on the coast, is the economic capital and is still the centre of all political administration.
There are a number of factors that have combined to slow the pace of exploration in the country, including episodes of political unrest and delayed regulatory process, a historical agricultural-based economy and a deeply-weathered regolith profile with sometimes dense tropical vegetation. It is now apparent that the country may be entering a period of political and economic stability after 2010 presidential and 2011 parliamentary elections and there are proposed amendments to the Minerals regulatory system to expedite permitting. Côte d’Ivoire retains much of what was the historically considered to be the most advanced infrastructure in the region, with good road and power networks and active ports at Abidjan and San Pedro.
Introduction to Birimian Gold
The two decades has seen a marked increase in the level of gold exploration in West Africa, initially dominated by Ghana, but increasingly in Burkina Faso, Mali, the southwest corner of Niger, eastern Senegal, northern Guinea, and Côte d’Ivoire. The application of sensitive exploration techniques developed in similar geological and regolith conditions in Australia and eastern Africa, and more efficient drilling techniques has resulted in the discovery of a number of new multi million ounce gold deposits.
The Birimian is a term to describe a collection of Paleoproterozoic metasedimentary and metavolcanic units and associated intrusive complexes that are the dominant hosts of gold deposits in West Africa. The larger gold deposits are located within structural corridors that may extend for up to 100km along strike. Birimian gold mineralisation is often concentrated along the margins of volcanic belts, with mesothermal gold deposits localised along faults and shears that cut through the greenstone sequences, and are defined by zones of alteration and quartz +/- carbonate veining. Commercial mineralisation is dominantly quartz vein-controlled and may be found in a variety of rocks and structural settings with metasediments being the most common host rock, particularly where intruded by felsic dykes and sills. Important mineralisation is also found in intermediate to mafic intrusive volcanic rocks and, volcanoclastic units. Quartz veins may contain both free gold and mineralisation associated with sulphides.
Geological exposures in the region are commonly deeply-oxidised to clays as a result of a tropical weathering environment, and may be capped or overlain by a cemented ferruginous laterite layer that may be either in-situ (and suitable for surface geochemical exploration), or transported (where surface geochemistry may be unsuitable). A generally subdued topography and widespread alluvial channels also adds to the exploration challenge. The combination of the regolith conditions described above means early-stage exploration is reliant on accurate mapping, geochemical sampling, geophysical interpretation, and the use of geochemical drilling tools such as auger, RAB and aircore.
Ancient gold production was initially sourced from Mali and Guinea and then later discoveries in Ghana and Côte d’Ivoire. It is thought that historical production in Ghana alone to the year 2000 may have been as much as 80Moz of gold (Minerals Commission, 2002). Modern gold exploration and mining has been led by Ghana, with more recent development in Mali, Burkina Faso, Guinea, Niger, Senegal and Côte d’Ivoire.
Larger deposits in Ghana include Obuasi, Bogoso, Prestea, Aykem (the Ashanti Belt), and the Bibiani, Chirano, Ahafo Yamfo, Sefwi deposits (Sefwi-Bibiani Belt). In Mali larger deposits include Loulo, Sadiola, Morilla and Syama, in Guinea – the Siguiri and Lero deposits, and in Côte d’Ivoire the Tongon, Sissingue, Bonikro, and Agbaou mines. In the context of global gold producers these are large gold deposits and together they demonstrate the significant potential of West Africa despite the relatively early exploration maturity. This is particularly the case in Côte d’Ivoire which shares borders with producing goldfields in Ghana, Mali, Burkina Faso and northeast Guinea.