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Lithostratigraphic evolution of the Bandamian Volcanic Cycle in central Côte d'Ivoire: Insights into the late Eburnean magmatic resurgence and its geodynamic implications

Peter M. Scott, Christopher M. Fisher, Noreen J. Evans, Anthony Kemp, Mark Jessell, Patrick Hayman, Quentin Masurel, Nicolas Thébaud, Nicolas Mériaud

Late- to post-collisional volcanism in the southern portion of the West African Craton (sWAC) has been described along the paleo-craton margin between the Paleoproterozoic Baoulé-Mossi domain and Archean Kénéma-Man nucleus. New lithostratigraphic and isotopic data for central Côte d'Ivoire, as well as revised regional stratigraphic correlations across the western sWAC, indicate that this volcanic resurgence is not only restricted to the paleo-craton margin, but extends to most greenstone belts of the western half of the sWAC. This late volcanic event, historically referred to as the ca. 2117–2080 Ma Bandamian Volcanic Cycle, has received little attention since its identification in 1996. Detailed geological investigation of the Bouaflé granite-greenstone belt in Côte d'Ivoire, located 150 km east of paleo-craton margin, along with newly acquired U-Pb geochronological data indicate a peak in igneous activity showing evidence for bimodal magmatism affiliated to the Bandamian Volcanic Cycle in central Côte d'Ivoire between 2108 ± 5 Ma and 2105 ± 4 Ma. Whole-rock geochemistry and Lu-Hf isotopic measurements on magmatic zircons from the Bouaflé region show that these Bandamian rocks are marked by a juvenile signature with little degree of crustal contamination. Collectively, the data collected in this study show that the Bandamian Volcanic Cycle represents an important thermal event that affected the sWAC during the late stages of the Eburnean orogeny, spanning the incremental change from folding and thrusting to dominantly transcurrent tectonics along major faults and shear zones. This paper discusses the possible geodynamic settings that may account for such a peak in thermal activity during the late stages of the Eburnean orogeny.