Geology of Ghana

The geology of Ghana is primarily very ancient crystalline basement rock, volcanic belts and sedimentary basins, affected by periods of igneous activity and two major orogeny mountain building events.

Main Precambrian rock units include the metamorphosed and folded Dahomeyan, Birimian, Tarkwaian System, Togo Series, and the Buem Formation.

[1] Paleoproterozoic rock units belonging to Birimian Supergroup, common across West Africa, dominate northwest and southwest Ghana.

The Birimian Supergroup has two units, one a succession of sedimentary rocks including phyllite, tuff and greywacke overlain by conglomerate, sandstone and shale and the other a volcanic tholeiitic magma series.

The Dahomeyan System comprises both mafic and felsic gneiss while the Togo Series includes quartzite, shale and small amounts of serpentinite.

The Volta Basin formed during the Neoproterozoic and includes the one kilometer thick sandstones and claystones of the Bambouaka Supergroup, which emplaced between 1.1 billion and 700 million years ago.

The 2.5 kilometer thick, 600 to 700 million year old Pendjari Supergroup has tillite and dolomitic limestone, rich in barite and silixite at its base and siltstone and argillite in its upper layers.

The third major unit in the Volta Basin is the Tamale Supergroup, with a thickness of 500 meters, claystone and siltstone at its base, giving way to coarse sandstone.

The past 66 million years of the Cenozoic are mainly recorded with marine, lagoonal and riverine sedimentary rocks as well as with unconsolidated sediments that cover most of the country and form soils.

The country also has small, poorly researched deposits of asbestos, chromite, andalusite, mica, barite, cassiterite, columbite, monazite, beryl, spodumene and molybdenite.

[9] Ghana has widespread quarrying of sand, gravel, kaolin and other clay deposits for road and building construction as well as brick production.