Petrography and Origin of Metasediments in the Odienné and Touba Area (NW Côte d’Ivoire)

The study area encompasses the Odienné and Touba sectors in northwestern Côte d’Ivoire. It is located in the Archean-Paleoproterozoic Transition Zone (APTZ), the major structure of which, the Sassandra Shear Zone (SSZ) trending NS then NW-SE, moulds the Archean core (or nucleus). The main lithologies occurring in this region include metasediments, gneisses (migmatites and mylonites), metabasites, and granitoids. This paper highlights new data on the petrographic characteristics and geochemical signature of the metasediments from northwestern Côte d’Ivoire. Field observations and petrographic studies reveal that the metasediments consist of mylonitic-textured quartzite, sillimanite paragneiss, and quartz-rich micaschists, along with garnets or amphibole. Geochemical data has enabled us to narrow down the origin of the metasediment rocks: one sample mainly consists of litharenite sandstone. They also show that their protoliths are basaltic, andesitic, granodioritic, and granitic rocks that are moderately to slightly altered (50 < AIC < 65) and that they were emplaced in a tectonic environment that could be of the island arc margin and/or continental margin type.