Abstract The West African Craton is defined by the presence of Archaean and Palaeoproterozoic (Birimian) rocks. Since 1990, researchers have published several papers proposing various regional scale accretionary models for the evolution of the Birimian series and the Eburnean orogeny. The Birimian lithostratigraphic succession starts with a major sequence of tholeiitic pillow basalts with intercalations of sediments, overlain by detrital and carbonate sediments, associated with calc-alkaline volcanics and plutons. A global scheme for the geodynamical evolution can be reasonably constrained using the characteristics of early tholeiitic plutono-volcanic and granitoid rocks. Geochemical, geochronological and structural characteristics of Palaeoproterozoic magmatic rocks of the Man-Leo Shield distinguish three tholeiitic (PTH1, PTH2, PTH3) and two granitic (PAG, PBG) series and date three principal events that have characterized the 2250–2000 Ma period: (1) Event I (2250–2200 Ma) characterized by tholeiitic volcanism with a widespread first tholeiite generation (PTH1), interpreted as the eruption of a mantle plume in an oceanic basin floor; (2) Event II (2200–2150 Ma) marked by second (PTH2) and third (PTH3) tholeiite generations and a calc-alkaline magma setting; high granitization and amphibole-bearing (PAG) granitoid emplacement with greenstone belt deformation. This event has been favoured by a crustal subsidence in a broad synclinorium mega-structure followed by vertical tectonics; (3) Event III (2150–2000 Ma) characterized by main biotite±muscovite (without amphibole) bearing (PBG) granitoid emplacement in a context of transcurrent deformation. There are many similarities between West African Palaeoproterozoic rocks and Archaean formations and their crustal evolution also may be similar.

Abstract Paleoproterozoic terranes of the Man-Leo Shield in the southern part of the West African craton host one of the world’s largest gold provinces with an overall endowment >10,000 metric tons (t). Although gold deposition commenced by ca. 2170 Ma, most deposits formed later, either during the inversion and metamorphism of intraorogenic sedimentary basins between ca. 2110 and 2095 Ma, or during later transcurrent deformation and associated widespread high K plutonism following docking of Archean and Paleoproterozoic domains within the craton at ca. 2095 Ma. Deposits formed between ca. 2110 and 2095 Ma include those with free gold in quartz veins and refractory gold in arsenopyrite and/or pyrite, and are associated with halos of carbonate, sericite, chlorite, and albite alteration. Most are located in bends and intersections between shear zones, minor faults, folds, and entrained blocks of relatively reactive igneous rock. Conglomerate-hosted gold deposits of the Tarkwa district formed early in the 15-m.y.-long period. Gold deposits that formed subsequently between ca. 2095 and 2060 Ma have a wider variety of styles, geologic settings, and metal assemblages. District-scale albite, carbonate, and tourmaline alteration, hydrothermal breccias, and a close relationship to high K granitoids characterize some of these deposits, whereas others are more typical orogenic gold deposits that are similar to those formed earlier during the craton evolution.