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The Paleoproterozoic rocks in the Kedougou Kenieba Inlier (KKI) consist of volcanic and volcanosedimentary rocks intruded by granitoids with a wide compositional spectrum. Geochronological data based on single-grain zircon Pb-Pb evaporation, U-Pb single grain, Ar-Ar and K-Ar dating of several plutons point to a long lasting emplacement history in the KKI. The zircon data presented here yielded Paleoproterozoic ages for the emplacement/crystallization of the Badon granodiorite (2213 ± 3 to 2198 ± 2 Ma), tonalitic gneiss from Sandikounda (2194 ± 4 Ma), the Tinkoto pluton (2074 ± 9 Ma) as well as for the felsic host rocks of the Mamakono pluton (2067 ± 12Ma). The Badon granodiorite, formerly regarded to be relatively young and post-tectonic, is substantially older than all other known KKI intrusions. As a consequence, this new age may constrain the ongoing discussion on the existence of an Early Birimian cycle in the West African Craton (WAC). Ar-Ar and K-Ar ages on hornblende (2112 ± 12 and 2118 ± 31 Ma, respectively, in the tonalitic gneiss from Sandikounda) and biotite (2098 ± 26 and 2090 ± 21 Ma, respectively, in the Badon granodiorite) define an age of ca 2090 Ma, which is interpreted to mark the major tectonomagmatic episode in this part of the WAC. This is confirmed by the Paleoproterozoic ages of the Saraya, Tinkoto and Mamakono granite. A hydrothermal event at 2020 Ma followed the emplacement of the granitoids and caused the alteration of the Saraya granite. The new zircon ages, reflecting the magmatic and tectonothermal events in the study area correlate well with various magmatic and metamorphic events elsewhere in West Africa.

Birimian (Paleoproterozoic) granitoids and associated volcanic and sedimentary rocks from the Kedougou-Kenieba-Inlier (KKI) of Eastern Senegal have been analyzed for their major, trace, REE concentrations and their Sr-Nd isotopic compositions. The calc-alkaline I-type granitoids were previously divided into several structural groups. The new geochemical data, however, do not give evidence for this subdivision into pre-, syn- and post-deformational intrusions. The results demonstrate the juvenile character of the granitic igneous rock suite and its isotopic similarities to the adjacent volcanic Mako and sedimentary Diale-Dalema Supergroups. The Birimian rocks show uniform juvenile features such as low initial Sr isotopic composition (~0.700 to ~0.704), positive ∑Nd(t) values (2.1 to 4.3) and restricted Nd model ages (~2.0 to ~2.3 Ga). They preclude the contamination of the juvenile Birimian crust of the KKI by notable amounts of reworked Archean crustal material. Comparison with existing data helps to clarify the complex evolution of Birimian Supergroups of the WAC. It can be concluded that the Birimian rocks are the product of a large-scale crustal growth process with large amounts of juvenile crust formed from the depleted mantle in a geodynamic environment compared to modern volcanic arcs. These bimodal volcanic arcs were later accreted to the WAC.