Geology of Senegal

The Archean greenschist Birimian rocks common throughout West Africa are the oldest in the country, intruded by Proterozoic granites.

With the rifting apart of the supercontinent Pangaea in the Mesozoic, the large Senegal Basin filled with thick sequences of marine and terrestrial sediments.

Two major north–south faults, formed in the Cretaceous through the late Miocene, break up the basin into horsts and grabens.

The sedimentary sequence begins with Triassic evaporite, gypsum, halite and anhydrite, which coincided with a tholeiitic magma series.

The Albian through the Turonian are represented by argillite and organic-rich sediments, followed by biochemical precipitation since the Paleocene epoch of the Cenozoic.

By the early Cenozoic, the ocean retreated, except in the Casamance Gulf and by the Eocene, the region was experiencing intense, terrestrial weathering.

The Cap-Vert experienced two peaks of volcanism, one in the Miocene and the other in the Quaternary, producing small occurrences of undersaturated, alkaline lavas.

This 250 meter thick aquifer is the main water supply for much of Senegal, and experiences comparable salinity and iron contamination issues.