Le prospect de Woulo-Woulo est situé au sud-est de la Côte d’Ivoire, précisément  dans la zone de Maféré, à environ 8 km à l’ouest du couloir de cisaillement d’Aféma. Les activités de terrain et de forage ont montré que certaines formations observées sur le prospect de Woulo-Woulo contiennent de la minéralisation aurifère. L’objectif général de cette étude est de déterminer les caractéristiques pétrographiques et structurales de ces roches et la minéralisation aurifère associée. Ainsi, l’acquisition des données a consisté au prélèvement d’échantillons de roches de terrain et de forage carotté, suivi de leur caractérisation macroscopique et microscopique. Le prospect de Woulo-Woulo est constitué de métasédiments (métagrauwackes et métaargilites), de métavolcanites (laves andésitiques et brèches), de filons acides (métarhyolite à porphyre de quartz) et d’intrusions de métagabbros, tousp affectées par une importante activité hydrothermale, filonienne, qui a induit une altération pervasive des encaissants. La minéralisation aurifère du prospect de Woulo-Woulo est de type filonien et hydrothermal épigénétique liée aux veines et veinules de quartz et carbonates, encaissée préférentiellement dans la métarhyolite porphyrique déformée et hydrothermalisée. Elle présente donc un contrôle structural. La paragenèse de cette minéralisation est constituée de pyrite (sulfure principal), sphalérite et or natif.   The Woulo-Woulo prospect is located in south-eastern Côte d'Ivoire, precisely in the Maféré zone, approximately 8 km west from the Aféma shear zone. Field and drilling activities have shown that certain formations observed at the Woulo-Woulo prospect contain gold mineralization. The overall objective of this study is to determine the petrographic and structural characteristics of these rocks and the associated gold mineralization. Thus, data acquisition consisted of field and core sampling followed by macroscopic and microscopic characterization. The Woulo-Woulo prospect consists of metasediments (metagrauwackes and metaargilites), metavolcanites (andesitic lavas and breccias), felsic veins (quartz porphyry metarhyolite) and metagabbro intrusions, all affected by significant hydrothermal and vein activity, which induced pervasive alteration of host rocks. The gold mineralization at the Woulo-Woulo prospect is vein-type and epigenetic hydrothermal type related to quartz and carbonate veins and veinlets, hosted preferentially in the deformed and hydrothermalized porphyry metarhyolite. It is therefore structurally controlled. The paragenesis of this mineralization consists of pyrite (main sulfide), sphalerite and native gold.

The gold mineralization of the Tondabo prospect, located in the northern part of the Oumé-Toumodi-Fettêkro greenstone belt, is mainly hosted in the rhyodacite and to a lesser extent in the mafic volcanics (volcanic lavas and volcanoclastites). These rocks were affected by a hydrothermal alteration marked by quartz veins and veinlets associated with crystals of carbonates, sericite, epidote and sulfides. This hydrothermal alteration induced a pervasive alteration of the surrounding bodies with silicification, chloritization, carbonation and sericitization of the feldspars. The metalliferous paragenesis contains an abundant pyrite, with rare pyrrhotite and chalcopyrite. This mineralization indicates that the Tondabo gold prospect exhibits lithological control. The mineralized deposits are generally affected by a S1 schistosity oriented mainly N000-010˚ and minority N040-050˚ with a general dip of 60˚-80˚ to the West; however with rare N-S orientations with a dip of 60˚-80˚ to the East. The drilling intervals show that the highest gold contents are linked to the quartz-carbonates veins and veinlets, which are located in the highly deformed zones, characterizing local shear zones.

The southern part of Toumodi-Fètêkro greenstone belt is located in the Center -Southeast of Ivory Coast. Petrographic study of volcanic and plutonic rocks shows three units. The first unit is composed of basaltic to rhyolitic lavas which imply effusive character. Then we have volcanosedimentary unit composed of pyroclastic formations (lapilli tuff, breccia, ash deposit and ignimbrites) and the pillow-lavas. Indeed, the presence of this last shows clearly that an explosive volcanism and a submarine effusive volcanism have occurred during during the setting of Toumodi-Fètêkro belt. Plutonic unit is constituted of gabbroic to granitic rocks. Sericite, chlorite, epidote observed in these rocks are consistent with the impacts of greenschist facies metamorphism. The rocks of the southern part of the Toumodi-Fètêkro greenstone belt are formed in a subduction context rather than in oceanic plateaus context because of the old inheritance, sometimes of Archean age, found somewhere in theBirimiandomain. The lithologies of the southern part of Toumodi-Fètêkro meet elsewhere in the other Birimian greenstone belts. Also, these lithologies are affected by a hydrothermal alteration due to the abundant veins of quartz, carbonates, sericite, chlorite, epidote, sulphides and oxides. However, volcanic show in some places amphibolit facies metamorphism. Keywords

La zone nord de Toumodi est située dans la partie sud du sillon de Toumodi-Fètêkro, au centre de la Côte d’Ivoire. Cette zone étant fortement latéritisée, une cartographie à partir du régolithe en vue de l’amélioration des connaissances de la géologie de la partie sud du sillon de Toumodi-Fètêkro a été initiée. Elle s’est faite grâce à la télédétection et aux données de sondage réalisés dans la zone. Ainsi, il ressort de cette étude que le régolithe de la zone d’étude provient de l’altération supergène des différentes formations géologiques observées et se caractérise par un profond profil d'altération d’épaisseur moyenne d’environ 18 m avec une distribution spatiale de régolithe relique, d'érosion, de dépôt ainsi que des surfaces affectées par une latéritisation généralisée.   The northern area of Toumodi is located in the southern part of the Toumodi-Fètêkro Trench in central Côte d'Ivoire. In order to improve knowledge of the regolith and geology of the southern part of the Toumodi-Fètêkro Trench, a regolith mapping study was initiated. This was done using remote sensing and borehole data from the area. Thus, it appears from this study that the regolith in the study area comes from the supergene alteration of the different geological units observed and is characterized by a deep alteration profile with an average thickness of about 18 m with a spatial distribution of relict regolith, erosion, deposition as well as surfaces affected by a generalized lateritization.

SAV'OR-CI's semi-industrial mine is located in Groudji, (Djékanou department), in the central-eastern part of Côte d'Ivoire, in the southern part of the Oumé-Fétékro birimian greenstone belt (West African craton). The Birimian terrains was affected by multiple deformation and mineralization events. This study is a contribution to resolve some issues in the Bririmian such as the improvement of petrography and knowledge. The methodology is on macroscopic to microscopic observations. The lithology of SAVO'R gold mine consists of four major units. The first unit, volcanic, made of volcanic lavas (metabasalt and rhyodacite) and volcaniclastics (mafic tuffs and felsic volcaniclastics). The second unit is a plutonic rocks which is summarized by metagranodiorites and granodiorites. The third unit which outcrops in the form of vein is represented by aplites and microgranites. The last unit is composed of metamorphic rock, precisely gneisses. The presence of lavas, and volcaniclastics reveal respectively that the effusive volcanism and the explosive volcanism have occurred during the setting of area rocks. All lithologies have been affected by hydrothermal alteration marked by quartz veins and veinlets, feldspars, carbonates, often associated with sericite, chlorite and sulphides. Gold is not visible to the eye in the observed lithologies. These rocks are affected by a metamorphism of greenschist facies marked by the presence of chlorite, sericite and epidote minerals.