[ Les sous-groupes Schisto-calcaire et de la Mpioka dans la chaine panafricaine West-Congo: Témoins de l’évolution paléoclimatique post-Cryogénien, Province du Kongo Central, R.D. Congo ]
Volume 35, Issue 2, January 2022, Pages 359–366
L. O. Tuema1, M. J. A. Makutu2, M. T. Kanika3, and C. M. E. Cibambula4
1 Université de Kinshasa, Faculté des Sciences, Département des Géosciences, Géologie, Post office Box 190, Kinshasa XI, RD Congo
2 Université de Kinshasa, Faculté des Sciences, Département des Géosciences, Géologie, Post office Box 190, Kinshasa XI, RD Congo
3 Université de Kinshasa, Faculté des Sciences, Département des Géosciences/Géologie, Post Office Box 190, Kinshasa XI, RD Congo
4 Université de Kinshasa, Faculté des Sciences, Département des Géosciences, Géologie, Post office Box 190, Kinshasa XI, RD Congo
Original language: French
Copyright © 2022 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.
Above the upper Diamictite of West Congolian Group, carbonate rocks of the Schisto-Calcaire Subgroup are superimposed, topped by the Bangu-Niari conglomerates and the Mpioka formations. Just as lithology varies from low to high, climates change regularly during sedimentation. By the presence of evaporites and bioherms of Collenia and Cryptozoon in the Kwilu and Lukunga formations, the Schisto-Calcaire Subgroup is characterized by a hot and arid climate developed in the Ediacaran after the glaciation of the Marinoen (635 Ma). The coarser-filled hollows than the grains of the substratum, the clast- to matrix-supported structures and the nature of its moderately misclassified clasts in large volumes of clays and silt indicate that the Bangu-Niari conglomerate has developed in a periglacial environment during the Terneuvien. The granular and repeated bedding of shales from the Lower and Upper Mpioka formations of Cambro-Ordovician age is reminiscent of the varval rhythms of periglacial lakes. These various previous elements show that after the non-longitudinal Marine Snowball, the Congo-Sao Francisco megacraton successively underwent a dry tropical climate and a temperate climate of proglacial regions.
Author Keywords: Upper Diamictite, Schisto-Calcaire, conglomerate, climate, hot, evaporites, bioherms, glaciation, Marinoen, palaeoenvironment, periglacial, granular and repeated bedding, varval rhythms, Congo-Sao Francisco megacraton.
Volume 35, Issue 2, January 2022, Pages 359–366
L. O. Tuema1, M. J. A. Makutu2, M. T. Kanika3, and C. M. E. Cibambula4
1 Université de Kinshasa, Faculté des Sciences, Département des Géosciences, Géologie, Post office Box 190, Kinshasa XI, RD Congo
2 Université de Kinshasa, Faculté des Sciences, Département des Géosciences, Géologie, Post office Box 190, Kinshasa XI, RD Congo
3 Université de Kinshasa, Faculté des Sciences, Département des Géosciences/Géologie, Post Office Box 190, Kinshasa XI, RD Congo
4 Université de Kinshasa, Faculté des Sciences, Département des Géosciences, Géologie, Post office Box 190, Kinshasa XI, RD Congo
Original language: French
Copyright © 2022 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
Above the upper Diamictite of West Congolian Group, carbonate rocks of the Schisto-Calcaire Subgroup are superimposed, topped by the Bangu-Niari conglomerates and the Mpioka formations. Just as lithology varies from low to high, climates change regularly during sedimentation. By the presence of evaporites and bioherms of Collenia and Cryptozoon in the Kwilu and Lukunga formations, the Schisto-Calcaire Subgroup is characterized by a hot and arid climate developed in the Ediacaran after the glaciation of the Marinoen (635 Ma). The coarser-filled hollows than the grains of the substratum, the clast- to matrix-supported structures and the nature of its moderately misclassified clasts in large volumes of clays and silt indicate that the Bangu-Niari conglomerate has developed in a periglacial environment during the Terneuvien. The granular and repeated bedding of shales from the Lower and Upper Mpioka formations of Cambro-Ordovician age is reminiscent of the varval rhythms of periglacial lakes. These various previous elements show that after the non-longitudinal Marine Snowball, the Congo-Sao Francisco megacraton successively underwent a dry tropical climate and a temperate climate of proglacial regions.
Author Keywords: Upper Diamictite, Schisto-Calcaire, conglomerate, climate, hot, evaporites, bioherms, glaciation, Marinoen, palaeoenvironment, periglacial, granular and repeated bedding, varval rhythms, Congo-Sao Francisco megacraton.
Abstract: (french)
Au-dessus de la Diamictite supérieure du Groupe Ouest-Congolien, se superposent les roches carbonatées du Sous-groupe Schisto-Calcaire surmontées par les conglomérats de Bangu-Niari et les formations de la Mpioka. Tout comme la lithologie varie de bas en haut, les climats changent régulièrement lors de la sédimentation. Par la présence des évaporites et des biohermes à Collenia et à Cryptozoon dans les formations de Kwilu et de Lukunga, le Sous-groupe Schisto-Calcaire est caractérisé par un climat chaud et aride développé à l’Ediacarien après la glaciation du Marinoen (635 Ma). Les creux à remplissage plus grossier que les grains du substratum, les structures clast- à matrix-supported et la nature de ses clastes modérément mal classés dans des grands volumes d’argiles et de silt indiquent que le conglomérat de Bangu-Niari s’est développé dans un paléomilieu périglaciaire au cours du Terreneuvien. Le litage granoclassé et répété de shales des formations de la Basse- et de la Haute-Mpioka d’âge Cambro-Ordovicien rappelle celui des rythmites varvaires des lacs d’environnement périglaciaire. Ces différents éléments précédents montrent qu’après le Snowball marinoen non latitudinal, le mégacraton du Congo-Sao Francisco a successivement subi un climat tropical sec et un climat tempéré de régions proglaciaires.
Author Keywords: Diamictite supérieure, Schisto-calcaire, conglomérat, climat, chaud, évaporites, biohermes, glaciation, Marinoen, paléomilieu, périglacaire, litage granoclassé, rythmites varvaires, mégacraton du Congo-Sao Francisco.
How to Cite this Article
L. O. Tuema, M. J. A. Makutu, M. T. Kanika, and C. M. E. Cibambula, “The Schisto-limestone and Mpioka subgroups in the Pan-African West-Congo chain: Witnesses of post-Cryogenic paleoclimatic evolution, Kongo Central Province, D.R. Congo,” International Journal of Innovation and Applied Studies, vol. 35, no. 2, pp. 359–366, January 2022.
