[ Histoire sédimentaire de la formation de couverture dans les plateaux Batéké (République du Congo) à partir de la morphoscopie et l’exoscopie des grains de quartz: Implications paléoclimatiques ]
Volume 43, Issue 2, August 2024, Pages 409–422
Otongo Judicaël1, Gatsé Ebotehouna Chesther2, and Elenga Hilaire3
1 Laboratoire des Géosciences, Département de la Formation Doctorale, Faculté des Sciences et Techniques, Université Marien Ngouabi, Brazzaville, Republic of the Congo
2 Laboratoire des Géosciences, Département de la Formation Doctorale, Faculté des Sciences et Techniques, Université Marien Ngouabi, Brazzaville, Republic of the Congo
3 Centre de Recherches Géologiques et Minières, Brazzaville, Republic of the Congo
Original language: French
Copyright © 2024 ISSR Journals. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
This study aims to determine the paleoenvironments and paleoclimates of the cover formation in the Batéké plateaus. The methodology adopted consists of carrying out the morphoscopic and exoscopic study of the quartz grains of the sands of this formation. After washing the samples, drying and dry sieving on a column of 6 sieves, the grains were selected for observations. The morphoscopic study reveals the presence of clean matte round quartz grains and shiny blunt grains. These results show that these sands have undergone double transport, aeolian and aqueous. The exoscopic study shows the existence of traces of mechanical and chemical actions on the surface of the two types of quartz grains. Mechanical traces of aeolian and fluvial types including certain aeolian traces have been polished in the fluvial environment. The superposition of these microstructures makes it possible to paleoenvironments and reconstruct to deduce paleoclimates. These sands experienced two phases of sedimentary deposition and two phases of immobilization in pedological environments. The first phase of deposition is aeolian, then immobilization in the soil environment undersaturated with silica marked by the dissolution figures. The second phase of deposition is the resumption of aeolian deposition in a low-energy fluvial environment, then the environment evolved into a podzolic soil environment supersaturated in silica. This study shows that the arid period of the Holocene, around 3,000 BP, to which the age of this formation is attributed, experienced variations, the climate experienced a humid phase marked by the fluvial evolution of the sediments.
Author Keywords: Grain surface, microstructures, paleoenvironments, paleoclimates, Batéké plateaus.
Volume 43, Issue 2, August 2024, Pages 409–422
Otongo Judicaël1, Gatsé Ebotehouna Chesther2, and Elenga Hilaire3
1 Laboratoire des Géosciences, Département de la Formation Doctorale, Faculté des Sciences et Techniques, Université Marien Ngouabi, Brazzaville, Republic of the Congo
2 Laboratoire des Géosciences, Département de la Formation Doctorale, Faculté des Sciences et Techniques, Université Marien Ngouabi, Brazzaville, Republic of the Congo
3 Centre de Recherches Géologiques et Minières, Brazzaville, Republic of the Congo
Original language: French
Copyright © 2024 ISSR Journals. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract
This study aims to determine the paleoenvironments and paleoclimates of the cover formation in the Batéké plateaus. The methodology adopted consists of carrying out the morphoscopic and exoscopic study of the quartz grains of the sands of this formation. After washing the samples, drying and dry sieving on a column of 6 sieves, the grains were selected for observations. The morphoscopic study reveals the presence of clean matte round quartz grains and shiny blunt grains. These results show that these sands have undergone double transport, aeolian and aqueous. The exoscopic study shows the existence of traces of mechanical and chemical actions on the surface of the two types of quartz grains. Mechanical traces of aeolian and fluvial types including certain aeolian traces have been polished in the fluvial environment. The superposition of these microstructures makes it possible to paleoenvironments and reconstruct to deduce paleoclimates. These sands experienced two phases of sedimentary deposition and two phases of immobilization in pedological environments. The first phase of deposition is aeolian, then immobilization in the soil environment undersaturated with silica marked by the dissolution figures. The second phase of deposition is the resumption of aeolian deposition in a low-energy fluvial environment, then the environment evolved into a podzolic soil environment supersaturated in silica. This study shows that the arid period of the Holocene, around 3,000 BP, to which the age of this formation is attributed, experienced variations, the climate experienced a humid phase marked by the fluvial evolution of the sediments.
Author Keywords: Grain surface, microstructures, paleoenvironments, paleoclimates, Batéké plateaus.
Abstract: (french)
Cette étude a pour but de déterminer les paléoenvironnements et les paléoclimats de la formation de couverture dans les plateaux Batéké. La méthodologie adoptée consiste à mener l’étude morphoscopique et exoscopique des grains de quartz des sables de cette formation. Après divers traitements, les grains ont été observés à la loupe binoculaire pour l’étude morphoscopique, parmi lesquels, les grains ronds mats propres et émoussés luisants ont été sélectionnés pour l’exoscopie L’étude morphoscopique révèle la présence des grains de quartz ronds mats propres et des grains émoussés luisants. Ces résultats montrent que ces sables ont subi un double transport, éolien et aqueux. L’étude exoscopique montre l’existence des traces d’actions mécaniques et chimiques sur la surface des deux types de grains de quartz. Les traces mécaniques de types éoliens et fluviatiles dont certaines traces éoliennes ont été polies dans le milieu fluviatile. La superposition de ces microstructures permet de reconstituer les paléoenvironnements et en déduire les paléoclimats. Ces sables ont connu deux phases de dépôt sédimentaire et deux phases d’immobilisation dans les milieux pédologiques. La première phase de dépôt est éolienne, puis immobilisation dans le milieu pédologique sous-saturé en silice marqué par les figures de dissolution. La deuxième phase de dépôt est la reprise dépôt éolien dans un milieu fluviatile à faible énergie, puis l’environnement a évolué en un milieu pédologique podzolique sursaturé en silice. Cette étude montre que la période aride de l’holocène, vers 3.000 BP, dont est attribué l’âge de cette formation, a connu des variations, le climat a connu une phase humide marquée l’évolution fluviatile des sédiments.
Author Keywords: Surface des grains, microstructures, paléoenvironnements, paléoclimats, plateaux Batéké.
How to Cite this Article
Otongo Judicaël, Gatsé Ebotehouna Chesther, and Elenga Hilaire, “Sedimentary history of the cover formation in the Batéké plateaus (Republic of Congo) based on morphoscopy and exoscopy of quartz grains: Paleoclimatic implications,” International Journal of Innovation and Applied Studies, vol. 43, no. 2, pp. 409–422, August 2024.
