The study of Birimian granitoids is of great importance because it allows us to understand the architecture of the West African crust and the processes that shaped it. In order to contribute to the improvement of know...The study of Birimian granitoids is of great importance because it allows us to understand the architecture of the West African crust and the processes that shaped it. In order to contribute to the improvement of knowledge on the geodynamic context of the emplacement of certain granitoids of the West African craton, this article addresses some essential problems of the Birimian, namely distinguishing the real nature of the magmas and the mechanisms that generated this Birimian crust. On the West African craton, there are intrusive granites in volcano-sedimentary furrows, in meta-sedimentary basins and granites that form batholiths separating these structures. To provide an answer to this scientific concern, we conducted a comparative study of the granitoids of the Comoé basin (Tiassalé region) and those of the large batholith of Ferkessédougou (Daloa region). From this study, it appears that these Birimian granitoids have been identified as granites, granodiorites and tonalites in the Tiassalé region while in Daloa, they are assimilated to anatexites and granites. They present very diverse aspects and contexts of emplacement: the granitoids of the Comoé basin have characteristics of type I granite, indicating direct crystallization of mantle magmas in a syntectonic emplacement, while in the Daloa region, some granitoids are magmatic, others migmatitic or metasomatic, reflecting a certain complexity relating to their genesis.展开更多
The southern Ferkessédougou batholith in the center-west of Côte d’Ivoire is the study area. The geology of this area includes granitoids (granodiorite, two-mica granite, biotite granite and muscovite g...The southern Ferkessédougou batholith in the center-west of Côte d’Ivoire is the study area. The geology of this area includes granitoids (granodiorite, two-mica granite, biotite granite and muscovite granite) and metasediment panels. Petrographic studies were coupled with geochemical analyzes on the whole rock in order to provide new elements in the structural evolution of this portion of the West African craton. Petrographic data show that the basement of the Bonon area is partly identical to that of the northern part of the batholith. The structural data reveal three major phases of deformation that structured the study area. As for the geochemical data carried essentially on samples of granitoids, they indicated a high-k affinity the I type granite characteristics. The spectra of the REE normalized to chondrites, have moderate slopes with a fractionation highlighted by the ratios (La/Sm)N = 1.93 - 4.56 and (La/Yb)N = 7.69 - 32.28. The multi-element diagrams revealed negative anomalies in Ta-Nb implying the partial melting of a crust of TTG composition. Studies for the geotectonic environment have shown that the granitoids of the Bouaflé and Bonon region were emplaced in an arc environment associated with a subduction zone.展开更多
文摘The study of Birimian granitoids is of great importance because it allows us to understand the architecture of the West African crust and the processes that shaped it. In order to contribute to the improvement of knowledge on the geodynamic context of the emplacement of certain granitoids of the West African craton, this article addresses some essential problems of the Birimian, namely distinguishing the real nature of the magmas and the mechanisms that generated this Birimian crust. On the West African craton, there are intrusive granites in volcano-sedimentary furrows, in meta-sedimentary basins and granites that form batholiths separating these structures. To provide an answer to this scientific concern, we conducted a comparative study of the granitoids of the Comoé basin (Tiassalé region) and those of the large batholith of Ferkessédougou (Daloa region). From this study, it appears that these Birimian granitoids have been identified as granites, granodiorites and tonalites in the Tiassalé region while in Daloa, they are assimilated to anatexites and granites. They present very diverse aspects and contexts of emplacement: the granitoids of the Comoé basin have characteristics of type I granite, indicating direct crystallization of mantle magmas in a syntectonic emplacement, while in the Daloa region, some granitoids are magmatic, others migmatitic or metasomatic, reflecting a certain complexity relating to their genesis.
文摘The southern Ferkessédougou batholith in the center-west of Côte d’Ivoire is the study area. The geology of this area includes granitoids (granodiorite, two-mica granite, biotite granite and muscovite granite) and metasediment panels. Petrographic studies were coupled with geochemical analyzes on the whole rock in order to provide new elements in the structural evolution of this portion of the West African craton. Petrographic data show that the basement of the Bonon area is partly identical to that of the northern part of the batholith. The structural data reveal three major phases of deformation that structured the study area. As for the geochemical data carried essentially on samples of granitoids, they indicated a high-k affinity the I type granite characteristics. The spectra of the REE normalized to chondrites, have moderate slopes with a fractionation highlighted by the ratios (La/Sm)N = 1.93 - 4.56 and (La/Yb)N = 7.69 - 32.28. The multi-element diagrams revealed negative anomalies in Ta-Nb implying the partial melting of a crust of TTG composition. Studies for the geotectonic environment have shown that the granitoids of the Bouaflé and Bonon region were emplaced in an arc environment associated with a subduction zone.
