[ Etude pétrographique des roches basiques de la partie supérieure du super groupe de Mbuji-Mayi ]
Volume 46, Issue 2, January 2020, Pages 153–164
Ungu Ramazani Derick1 and Malu Wa Kasanda Gianny2
1 Faculté des Sciences, Département des Géosciences, Université de Kinshasa, Kinshasa, RD Congo
2 Department, Ministère des Hydrocarbures, Kinshasa, RD Congo
Original language: French
Copyright © 2020 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.
The Mbuji-Mayi super group, a large basin with a synclinal structure, extends around the Mbuji-Mayi and LUILU rivers in the center of the Democratic Republic of Congo with a more extensive extension to West Kasai Occidental and Eastern Katanga regions. It is about a mainly sedimentary unit divided into three groups (series) with knowing: the group BI, BII and the group of basalts. The group BI is composed of the sedimentary rocks constituted of sandstone, of limestones, of cherts or silexites and of intraformationnel conglomerate. In the lower part of this group are clastic rocks. Group BII, characterized on all its thickness by stromatolithic bases, comprises in the BIIc formation of associations of micro-organisms. And at the top of this group are capped volcanic demonstrations precede great casting dolerites rich in pyroxene, olivine and opaque minerals (goethite, chalcopyrite) and of amygdaloid and chloritized basalts with subophitic structure with microlitic porphyritic. The presence of lithographic limestone and the conglomerate intraformationnel testifies at the same time to the existence of the deposits of platform and instability of this basin where gravitating flows (slumping type and currents of turbidity) would have remobilized sediments siliceous old, hardened they redeposit the fragments in the same natural sediment gorged with water and soft. Geochemical and petrological studies are recommended according level of alteration of samples of dolerites and basalts. They have identified the origin of these volcanic sites.
Author Keywords: Super group of Mbuji-Mayi, synclinal structure, group BI and BII, Basalts, dolerites, conglomerate intraformationnel, limestone.
Volume 46, Issue 2, January 2020, Pages 153–164
Ungu Ramazani Derick1 and Malu Wa Kasanda Gianny2
1 Faculté des Sciences, Département des Géosciences, Université de Kinshasa, Kinshasa, RD Congo
2 Department, Ministère des Hydrocarbures, Kinshasa, RD Congo
Original language: French
Copyright © 2020 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
The Mbuji-Mayi super group, a large basin with a synclinal structure, extends around the Mbuji-Mayi and LUILU rivers in the center of the Democratic Republic of Congo with a more extensive extension to West Kasai Occidental and Eastern Katanga regions. It is about a mainly sedimentary unit divided into three groups (series) with knowing: the group BI, BII and the group of basalts. The group BI is composed of the sedimentary rocks constituted of sandstone, of limestones, of cherts or silexites and of intraformationnel conglomerate. In the lower part of this group are clastic rocks. Group BII, characterized on all its thickness by stromatolithic bases, comprises in the BIIc formation of associations of micro-organisms. And at the top of this group are capped volcanic demonstrations precede great casting dolerites rich in pyroxene, olivine and opaque minerals (goethite, chalcopyrite) and of amygdaloid and chloritized basalts with subophitic structure with microlitic porphyritic. The presence of lithographic limestone and the conglomerate intraformationnel testifies at the same time to the existence of the deposits of platform and instability of this basin where gravitating flows (slumping type and currents of turbidity) would have remobilized sediments siliceous old, hardened they redeposit the fragments in the same natural sediment gorged with water and soft. Geochemical and petrological studies are recommended according level of alteration of samples of dolerites and basalts. They have identified the origin of these volcanic sites.
Author Keywords: Super group of Mbuji-Mayi, synclinal structure, group BI and BII, Basalts, dolerites, conglomerate intraformationnel, limestone.
Abstract: (french)
Le super groupe de la Mbuji-Mayi, vaste cuvette à structure synclinale, s’étend dans les environs des rivières Mbuji-Mayi et LUILU au centre de la République Démocratique du Congo avec un prolongement plus considérable à l’Ouest du Kasaï occidental et à l’Est du Katanga. Il s’agit d’un ensemble principalement sédimentaire divisé en trois groupes (séries) à savoir : le groupe BI, BII et le groupe des basaltes. Le groupe BI est composé des roches sédimentaires constituées des grès ou arénite quartzeuse, des calcaires, des cherts ou silexites ainsi que de conglomérat intraformationnel. Dans la partie inférieure de ce groupe se trouve des sédiments détritiques. Le groupe BII, caractérisé sur toute son épaisseur par des assises stromatolithiques, comporte dans la formation BIIc des associations de micro-organismes. Et au sommet de ce groupe se coiffent des manifestations volcaniques qui précèdent la grande coulée de dolérites riches en pyroxène, olivines et minéraux opaques (goethite, chalcopyrite) et de basaltes amygdaloïdes et chloritisés à structure subophitique à microlitique porphyrique. La présence du calcaire lithographique et du conglomérat intraformationnel témoigne à la fois de l’existence des dépôts de plateforme et de l’instabilité de ce bassin où des écoulements gravitaires (type slumping et courants de turbidité) auraient remobilisé des sédiments siliceux anciens, durcis dont ils redéposaient les fragments dans un sédiment de même nature gorgé d’eau et tendre. Les études géochimique et pétrologique sont recommandées au vue du niveau d’altération très élevée des échantillons des dolérites et basaltes. Elles permettront de bien identifier l’origine de ces venues volcaniques.
Author Keywords: Super groupe de Mbuji-Mayi, structure synclinale, groupe BI et BII, Basaltes, dolérites, conglomérat intraformationnel, calcaire.
How to Cite this Article
Ungu Ramazani Derick and Malu Wa Kasanda Gianny, “Petrographic study of basic rocks of the Mbuji-Mayi supergroup’s upper part,” International Journal of Innovation and Scientific Research, vol. 46, no. 2, pp. 153–164, January 2020.
