Petrogenesis and Geodynamic Setting of Paleoproterozoic Rocks from Zoukougbeu (Dalao, Central-Western Côte d’Ivoire): Insights from Petrography and Geochemistry

Abstract

The Paleoproterozoic basement of Zoukougbeu in central-western Côte d’Ivoire lies within the southern Baoulé-Mossi domain of the West African Craton, a key area for understanding the crustal evolution associated with the Eburnean orogeny. However, the petrogenesis and geodynamic context of the granitoid intrusions in this region remain poorly constrained, despite their potential significance for regional crustal growth and mineralization. This study integrates petrographic and whole-rock geochemical data from drill-core samples to clarify the origin and tectonic evolution of these rocks. The lithological assemblage includes granodiorite, granite, diorite, gneiss, and pegmatite, variably deformed and hydrothermally altered. Petrographic analysis reveals plagioclase-quartz-biotite-amphibole assemblages overprinted by chlorite-epidote alteration, indicating greenschist- to amphibolite-facies metamorphism. Geochemically, the rocks define a calc-alkaline, metaluminous to slightly peraluminous suite with tonalite-trondhjemite-granodiorite (TTG) affinity. Their enrichment in large-ion lithophile elements and depletion in Nb-Ta-Ti, coupled with LREE enrichment and negative Eu anomalies, are typical of subduction-related magmatism. These signatures indicate that the Zoukougbeu granitoids originated from partial melting of hydrated basaltic crust with minor mantle input in a continental volcanic-arc setting during the Eburnean orogeny (~2.1 - 2.0 Ga). This finding refines the current understanding of Paleoproterozoic crustal evolution in the southern West African Craton and highlights the role of arc magmatism in its stabilization.