Petrographic and Geochemical Characteristics of the Metabasites of the SASCA Domain (Yonaké, Mani- Béréby and Dehié Sectors), South-West Côte d'Ivoire

The petrographic and geochemical study of six (6) metabasites located in the Archean-Paleoproterozoic transition domain (SASCA domain, South- West Côte d'Ivoire) identified dolerites and gabbros. The thin sections revealed two textures: the doleritic texture (dolerite) and the granoblastic texture (gabbro). The dolerites are composed of plagioclase wands, pyroxene, and olivine. Gabbros have a composition of pyroxene (clinopyroxene), green hornblende, plagioclase, biotite, and rare quartz. Geochemical analysis, especially the major elements, corroborated the gabbroic character of the metabasites. Trace elements and rare earth helped to constrain the origin of the metabasites by showing: (i) their belonging to a tholeiitic series, (ii) a mantle source contaminated by the continental crust, and (iii) their emplacement in the field of intraplate or volcanic arc basalts

Mapping Sandy Titano-Uraniferous Deposits in Tabou Region, South-West Cote d’Ivoire: Contribution of Magnetometry and Gamma-Ray Spectrometry

The work of the Geological and Mining Research Office (BRGM) in Côte d'Ivoire, with Tagini and Papon, has revealed, in addition to substances such as gold and manganese, indications of nuclear substances in some areas of the country. Côte d'Ivoire's mining policy is to develop the riches of its subsoil. The lack of information on the reserves of nuclear substances does not currently allow the Ivorian state to exploit these nuclear resources. This work is part of the framework to deepen our knowledge on these substances.Carried out in the south-west of Côte d'Ivoire, along the coast, this study confirmed the reported uraniferous indications and helped to identify their origin. Uranium accumulations were found in beach sediments in significant quantities between Bliéron and Soublaké. Keywords: Uranium, Magnetometry, Gamma-ray spectrometry, Tabou, Côte d’Ivoire. DOI: 10.7176/JEES/12-11-02 Publication date: November 30th 2022

Petrography and Geochemistry for Proposal of Geodynamic Model For The Irbiben Granite in Tagragra d’Akka inlier, (western Anti-Atlas, Morocco)

This study aims to contribute to improve the knowledge on the setting of the Irbiben granites, located south of the gold deposit of this locality (Tagragra d'Akka buttonhole, Anti-Atlas, Morocco). The petrographic characterization showed leucocratic porphyry rocks, with a mineralogy dominated by quartz and phenocrysts of plagioclase, alkali feldspars of sometimes centimetric size as well as very small sulphides of metallic luster. Two generations of quartz have been identified: a QIquartz with undulating extinction phenocrysts testifying to an episode of deformation orchestrated in this inlier, and a QII quartz with more rounded and limpid minerals indicating an intense silicification. Plagioclase and alkali feldspars are deeply altered to sericite and epidote. Geochemical characterization classifies these rocks as calc-alkaline series granites, rich in potassium, with a peraluminous character indicating their crustal origin. Their arc geochemical signature, Ba enrichment, and negative Nb, Ti, and P anomalies are characteristic of a subduction zone. This subduction could be associated with an episode of convergence between an oceanic lithosphere located in the north and the West African craton in the south, as shown by the proposed geodynamic model

A tectonic model for the juxtaposition of granulite- and amphibolite-facies rocks in the Eburnean orogenic belt (Sassandra-Cavally domain, Côte d’Ivoire)

The Sassandra-Cavally (SASCA) domain (SW Côte d’Ivoire) marks the transition between the Archean Kenema-Man craton and the Paleoproterozoic (Rhyacian) Baoule-Mossi domain. It is characterized by the tectonic juxtaposition of granulite-facies and amphibolite-facies rocks. Migmatitic grey gneisses, garnet–cordierite–sillimanite migmatitic paragneisses and garnet–staurolite-bearing micaschists reached peak pressure conditions ranging from ∼ 6.6 kbar at 620 °C to ∼ 10 kbar at 820 °C. These conditions are associated with the first recorded deformation D1 and correspond to a Barrovian geothermal gradient of ∼ 25 °C/km. Subsequent exhumation, associated with a second deformation D2, was marked by decompression followed by cooling along apparent geothermal gradients of ∼ 40 °C/km. A D3 deformation phase is marked by folding and local transposition of the regional S1/S2 foliation into E-W trending shear zones. LA-ICP-MS U–Pb dating of monazite, which displays complex internal structures, reveals four age groups correlated to textural position of monazite grains and analytical points: (1) rare relictual zones yield dates at the Archean-Paleoproterozoic transition (ca. 2400–2600 Ma); (2) a cluster of dates centered at ca. 2037 Ma on grains aligned along the S2 foliation of the migmatitic grey gneiss, attributed to D2; (3) a cluster of dates centered at ca. 2000 Ma, and (4) dates spreading from ca. 1978 to 1913 Ma, documented for the first time in the West African Craton monazites. The ages of the latter two groups are similar to the ones identified in the Guiana Shield, and could be attributed to a disturbance by fluids, to a periodic opening of U–Pb system or to an episodic crystallization of monazite during slow cooling lasting several tens of Myrs. These data allow to propose a model for the tectonic evolution of the SASCA domain at the contact between the Rhyacian Baoule-Mossi domain and the Archean Kenema-Man nucleus whereby crustal thickening is achieved by crustal-scale folding and is followed by and concomitant with lateral flow of the thickened partially molten crust accommodated by regional transcurrent shear zones. This combination of crustal thickening controlled by tectonic forces and gravity-driven flow leads to the juxtaposition of granulite- and amphibolite-facies rocks

A tectonic model for the juxtaposition of granulite- and amphibolite-facies rocks in the Eburnean collision in the orogenic belt (Sassandra-Cavally domain, Côte d’Ivoire)

The Sassandra-Cavally (SASCA) domain (SW Côte d’Ivoire) marks the transition between the Archaean Kenema-Man craton and the Palaeoproterozoic (Rhyacian) Baoule-Mossi terranes. It is characterized by the tectonic juxtaposition of granulite-facies and amphibolite-facies rocks. Migmatitic grey gneisses, garnet-cordierite-sillimanite migmatitic paragneisses and garnet-staurolite-bearing micaschists reached peak pressure conditions ranging from ~6.6 kbar at 620°C to ~10 kbar at 820°C. These conditions are associated with the first recorded deformation D1 and correspond to a Barrovian geothermal gradient of ~25°C/km. Subsequent exhumation, associated with a second deformation D2, was marked by decompression followed by cooling along apparent geothermal gradients of ~40°C/km. A D3 deformation phase is marked by folding and local transposition of the regional S1/S2 foliation by E-W trending shear zones. LA-ICP-MS U-Pb dating of monazite, which displays complex internal structures, reveals four age groups as a function of their textural position: 1) Rare relictual zones yield dates at the Archaean-Palaeoproterozoic transition (c. 2400–2600 Ma); 2) a cluster of dates centered at c. 2037 Ma. This cluster includes dates from crystals located in the S2 foliation of the migmatitic grey gneiss, which suggests that this is the age for the D2 exhumation; 3) a cluster of dates centered at c. 2000 Ma, and 4) dates spreading from c. 1978 to 1913 Ma, documented for the first time in the West African Craton monazites. The ages of the latter two groups are similar to the ones identified in the Guiana Shield, and could be attributed to a disturbance by fluids, to a periodic opening of U-Pb system or to an episodic crystallization of monazite during slow cooling lasting several tens of Myrs. These data bring new petro-tectonic and geochronological constraints on the contact between the Rhyacian Baoule-Mossi terrains and the Archaean Kenema-Man nucleus, and confirm the collisional character of the polyphase tectono-metamorphic evolution of the SASCA domain during the Eburnean orogeny. They suggest a transitional regime between the predominance of gravitational instabilities and modern plate tectonics. The exhumation of the granulite- and amphibolite-facies rocks results from a combination of crustal-scale folding associated with lateral flow and regional transcurrent shear zones, which would explain the juxtaposition of rocks that reached significantly different P–T conditions

Abstracts of the 1st International Colloquium in Mine & Society

This book presents the abstracts of the selected contributions to the First International Colloquium on Mines and Society (CIMS) organized by The Higher Institute of Mining and Geology of Boke. The theme of this colloquium was "Mining and Sustainable Development, a major challenge for an Emerging Africa" which aims to bring together teachers, researchers, and Professionals from different backgrounds in order to exchange the results of their research work, share their points of view on the issue of mining and sustainable development. It also aims to define, in a collaborative and inclusive manner, research prospects or future projects between all the actors involved in this field. Colloquium Title: 1st International Colloquium in Mine & SocietyTheme: Mining and Sustainable Development, A Major Challenge for an Emerging AfricaColloquium Date: 20-22 May 2022Colloquium Location: A L’Hôtel Rio Nunez de BokeColloquium Organizer: The Higher Institute of Mining and Geology of Bok