The tectono-magmatic framework to gold mineralisation in the Sadiola-Yatela gold camp and implications for the paleotectonic setting of the Kédougou-Kénieba inlier, West Africa

Abstract The Kedougou-Kenieba inlier is the westernmost exposure of Birimian crust in the West African Craton. The inlier is host to several multi-million ounce gold deposits (e.g., Sadiola, Yatela, Loulo, Massawa, and Gounkoto) and a large iron ore resource (i.e. Faleme). Although the inlier has received increasing academic attention over the last decade, only limited data exists for its north-eastern part, which contains the world-class Sadiola-Yatela gold camp. New field data, U-Pb magmatic zircon ages, and whole rock geochemistry data from the north-eastern Kedougou-Kenieba inlier are presented and integrated with published data in order to generate a revised tectono-magmatic framework to gold mineralisation for the westernmost Birimian terranes. The granitoids from the Sadiola-Yatela region display a temporal evolution from ca. 2140 to 2080 Ma calc-alkaline metaluminous plutons (e.g., diorite, hornblende-biotite-granodiorite) to ca. 2080–2060 Ma high-K calc-alkaline, metaluminous to slightly peraluminous granites (e.g., biotite-monzogranite). The least-evolved rocks are associated with flat REE patterns and correspond to plutons of the ca. 2140 Ma Finman complex and the ca. 2115 Ma Sadiola quartz-feldspar porphyry. The vast majority of the Eburnean (ca. 2115–2060 Ma) granitoids in the Sadiola-Yatela region are characterised by negative Nb-Ta anomalies, marked Pb positive anomalies, and high LILE/HFSE ratios. These Eburnean granitoids share a close affinity with relatively hydrous, oxidised magmas and source regions. The polycyclic deformation recorded in sedimentary and magmatic rocks of the region includes a period of early convergence (D 1s ), followed by a period of fold-and-thrust tectonics (D 2s ), and later transcurrent tectonics (D 3s -D 4s ). The bulk of the gold mineralisation in the region occurred during D 3s , with sinistral displacement and hydrothermal fluid circulation along the Senegal-Mali Shear Zone and steep NNE-trending shear zones connected to structural traps in the Kofi basin. The results of this study, when integrated with published data, indicate an evolution from primitive island arc magmas to increasingly evolved high-K calc-alkaline granitic melts as a result of crustal thickening during the Eburnean orogeny combined with fractionated crystallisation and melting-assimilation-storage-homogenisation processes. The late Eburnean tectono-thermal event between ca. 2080 and 2060 Ma is proposed as the geodynamic engine that empowered gold mineralisation in the Kedougou-Kenieba inlier.