GEOLOGY OF KENYA

Dr. Cedric Simonet

Kenya has an an ancient and fascinating geology which suggests enormous potential for the mining industry

The oldest recorded rocks in Kenya are those of the Nyanzan greenstone belts and granites of Western Kenya. These low metamorphic grade formations (mostly metavolcanites, but also metasediments and banded iron formations) are the host of gold and copper mineralization, including the historical Macalder Mine near Migori. Kavirondianmetasediments, also Archean in age, also host to gold mineralization, including the Kakamega goldfields which were the site of a goldrush in the 1920s.

Much of Kenya is underlain by Neoproterozoic high metamorphic grade rocks of the Mozambique Belt. These include a variety of metasediments, metalimestones (marbles), amphibolites, orthogneisses and locally ophiolite remnants. Graphite gneisses are relatively common. They are host to a variety of mineral deposits including industrial minerals, gold, copper, iron ore, manganese, and most of the Country’s colored gemstone deposits.

Copper Ore Mined in Kishushe
© Cedric Simonet

The non-metamorphic Bukoban series in Western Kenya are overlying the Archean basement and are considered to be Neoproterozoic in age. Beside the production of soap-stone which is used for the crafting of souvenirs for tourists, the mineral potential of this rock formation (discordance-hosted ore body models) has not been fully appraised yet.

Clastic sediments of the Permo-Triassic Karoo formations are present in rift structures across the country, as well as in coastal basins, where they are best exposed. Their potential for coal deposits has not been fully assessed yet. Leaching and remobilization of trace elements from the feldspar component of arkoses has led to the formation of barite, lead, silver and zinc deposits, some of which have seen some mining activity.

Marine Mesozoic sediments outcrop mostly in the Eastern part of the Country, including along the Coast. The Jurassic age Kambe limestone hosts significant resources for cement, dimension stone as well as aggregates production.

Artisanal Mining Gold Nuggets Turkana

© Cedric Simonet

Manganese Ore, Kilifi

 © Cedric Simonet

Cenozoic and Quaternary sediments are found in the Eastern part of the Country, as well as within the Rift Valley, which traverses Kenya from North to South, following the structural directions of the Mozambique Belt. The Rift Valley is associated to intense volcanic activity from the lower Miocene, and much of Kenya is underlain by volcanic rocks. Of these, carbonatites have the most potential for mineral production.