Mapping, Petrostructural Analysis and Metallogeny of the Natiemboro Geological Formations in the Tortiya Area (North-Central Côte d’Ivoire)

Abstract

This study, which was conducted in the Natiemboro area of the Korhogo Department in north-central Côte d'Ivoire, aimed to improve our understanding of the region's petrography, structure and metallogenesis. To this end, a geological mapping campaign was carried out in combination with rock and soil sampling using satellite imagery. A total of 25 polished sections were prepared for petrographic, microstructural and metallogenic analysis. The mapping reveals four units: a metasedimentary unit consisting of sericite schists and quartzites ; a metaplutonic unit consisting of biotite metagranite, gneiss, and metamicrogranodiorite ; an intrusive unit consisting of fine- and coarse-grained granite ; and a unit consisting primarily of pegmatites. These units are primarily affected by green schist-facies metamorphism and also exhibit hydrothermal (pervasive and vein-type) and meteoric alteration. Pervasive hydrothermal alteration is exemplified by carbonation, sericitisation, chloritisation, epidotisation, silicification and sulphidation, while vein-type hydrothermal alteration is characterised by veins and dykes of quartz, carbonates and quartz-tourmaline. The metasedimentary complex exhibits S1 schistosity, which is oriented NNE-SSW or NE-SW with gentle dips of 40–46°. It is thought that regional NW-SE compression caused this schistosity. The metasedimentary and metaplutonic complexes are traversed by two main left-lateral shear zones oriented N-S and NE-SW, respectively. These shear zones are intersected by left- and right-lateral detachment faults and fractures oriented NW-SW, N-S to NNE-SSW and E-W. The NNE-SSW and N-S vein systems are associated with the shear zones and host gold mineralisation. These veins are mined by illegal gold panners.