U-Pb geochronological data from the northern and western extensions of the Oudalan-Gorouol volcano-sedimentary belt (OGB) on 3 samples of granodiorite gneiss (sample BF_1144), migmatitic gneiss (sample BF_1299), and granite clast from a metaconglomerate (sample BF_1147) gave the oldest U-Pb crystallisation ages for outcropping Palaeoproterozoic rocks yet identified in the West African Craton (WAC).The U-Ph concordant crystallisation ages of 2253 ± 9 Ma and 2253 ± 15 Ma for samples BF_1144 and BF_1299, respectively, likely represent the age of crystallisation of parent granodiorite gneiss and may constrain the age of a gneissic protolith on which the OGB hasin was deposited, or an early group of granitoids that was emplaced in the hinterland during formation of the OGB hasin.A concordant age of 2255 ± 26 Ma for sample BF_1147 is interpreted as the age of crystallisation of a granite pluton that was eroded from a site nearby before becoming part of the Dembam Member, and constrains the maximum age of the Birimian Supergroup in the OGB.The older Pb-Pb ages on zircons from the granodiorite gneiss, migmatitic gnei.ss and granite clast are in the range -2.34 tõ 2.21 Ga, and are interpreted as inherited from pre-existing zircon cores. They are similar to Pb-Pb ages reported as inherited zircon ages from the Dabakala tonalitic gneiss (in Cote d'Ivoire).
The southern part of the West African Craton includes the Baoulé-Mossi Domain, the world's premier Paleoproterozoic gold province (~10,000 metric ton gold endowment). Structural, metamorphic, and geochronological data suggest gold mineralisation occurred during three episodes that span much of the Eoeburnean and Eburnean orogenic cycles. Eoeburnean orogenic and rare skarn-hosted gold deposits formed between ca. 2200 and 2135 Ma during repeated episodes of volcanism, plutonism, and shortening, which thickened the Paleoproterozoic crust. Early Eburnean orogenic and placer gold deposits formed between ca. 2110 and 2095 Ma during inversion, metamorphism, and subsequent oblique shortening of intra-orogenic basins filled after ca. 2135 Ma. This episode of mineralisation terminated when the Baoulé-Mossi Domain docked with the Archean Kénéma-Man Domain at ca. 2095 Ma. Late Eburnean orogenic and less common intrusion-related gold deposits formed between ca. 2095 and 2060 Ma during strike-slip to oblique-slip tectonics, post-collisional high-K plutonism and crustal reworking across the western and southern Baoulé-Mossi Domain. Eoeburnean gold deposits include ca. 10 % of the gold endowment of the Baoulé-Mossi Domain, whereas the Early Eburnean and Late Eburnean deposits include ca. 50-70% and 20-40%, respectively. Here, we highlight the favourable confluence of accretion-collision tectonics, involving juvenile crust formation as well as protracted magmatic, metamorphic, and deformation histories that resulted in diachronous gold events spread over at least 100 myr throughout the Baoulé-Mossi Domain.
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