Petrographic and Geochemical Characteristics of the Séguéla Granitoids, Northwestern Côte d’Ivoire

Abstract

This paper focuses on the study of granitoids within the large transition zone of the seguela region in northwestern cote d’ivoire. This area is characterized, in its northern part, by the presence of a large porphyroid granitoid massif. Petrographic and geochemical analyses allow us to group the lithological units of the study area into three main facies: 1) granites, 2) granodiorite, and 3) migmatites. The granites have a calc-alkaline affinity and a slightly peraluminous chemistry, whereas the granodiorite and migmatites are generally metaluminous. The migmatites are moderately to strongly calc-alkaline. Similarities in the multi-element and rare-earth element spectra of the different lithologies suggest a common source of emplacement. However, the positive eu anomalies in the granites and the negative anomalies in the granodiorite and migmatites may indicate that the granites derived from the partial melting of a more or less differentiated crustal protolith with plagioclase remaining in the residue. We can therefore consider that the studied granitoids and migmatites were generated in subduction zones. This subduction is consequently responsible for the release of potassium-rich fluids, leading to the formation of pink granites rich in potassium feldspar.