Petrography and geochemistry of Paleoproterozoic metasediments of Bougouni Region, Southern Mali: Implication for provenance and tectonic setting

This study investigates the geochemical and petrographic characteristics of Paleoproterozoic metasedimentary rocks (greywackes, mica-schists and talc-schists) from the Bougouni region, southern Mali to assess their provenance, tectonic setting and paleo-weathering. These rocks are crucial for understanding the geodynamic evolution of the Birimian terrane in West Africa. Petrographic analysis, geochemical characterisation (including trace and major elements) and various weathering indices (chemical index of alteration, plagioclase index of alteration and ICV) were employed to evaluate their alteration and source area characteristics. Results show moderate alteration, with CIA values ranging from 54.39 to 77.19. The dominance of LILEs enrichment over HFSEs in the studied samples, the rare earth element patterns ((La/Yb)N = 14,76) and the negative europium anomalies (Eu/Eu* = 0.31) indicate a predominantly felsic to intermediate igneous provenance. The major and trace elements discriminating diagrams suggest that the Bougouni metasediments were deposited in a continental arc setting. This work extends prior research on the Birimian terrane by providing a detailed geochemical assessment of sediment provenance and tectonic setting, emphasising the role of Birimian granitoids as the probable primary source. The study contributes to understanding the Paleoproterozoic tectonic evolution in southern Mali.