GEOLOGY OF NIGERIA

Geology of Nigeria consists three major litho-petrological components namely; the basement complex, younger granites and the sedimentary basins.

The basement as well as the younger granites are hard rocks while the sedimentary basins comprises of soft rocks. Basement complex differs from younger granites in age, gneiss, petrologically and structurally. Basement; pan-African of about 600 million years and older precambriam beyond 600million years; produced by orogenically by a series of tectonic episodes i.e the pan- African, kibaran, eburnean, and Liberian. Petrologically, basement complex comprises of migmatite-gneiss complex, schist belts such as the Kusheriki, Karaukarau, Kazaure, Maru, Anka, Zuru, Iseyin-oyan river schist, Ilesa, Igarra schist belts, Pan-African granitoids and Undeformed acid and basic dykes.

Kibaran named after Kibara Mountains of eastern Zaire now Democratic Republic of Congo of 1300-900 million years. Pan-African of about 600 million year probably represented in northern Nigeria schist belts only.

Younger granites as was introduced by falconer (1911) to distinguish high level, discordant tin-bearing granites of northern Nigeria (younger granites) from deep seated, often concordant or semi-concordant granites the basement complex.

Younger granites are of the Jurassic age, anorogenic in origin, and petrologically comprises of ring complexes of;

Peralkaline granites and ferrorichterite- arfvedsonite granites, ferrodenite to ferroactinolite syenite.

Peraluminous biotite alkali feldspar granites and biotite syenogranites.

Metaluminous fayalite and hornblende- bearing granites and porphyries.

The ring complexes include; Birnin kudu, Zaranda, Mada, Sara-fier, Jos bukuru, Afu, Nok, Kagoro, Kigon, Rishua, Kudara, Amo and so on.

Basement Complex outcrops: 30 km north of Bauchi on the Bauchi – kari road. Basement

Complex rocks are generally low lying and concordant in contrast to the cross-cutting, discordant, and steeply occurring hilly outcrops in the form of ring dykes and cone sheets in the Younger Granites

To be contd.