Lithostratigraphic and sedimentological study of the Kimbungu massive in the Kongo- Central province.

The lithostratigraphic and sedimentological survey of rocks belonging to the summit of Sansikwa sub- group at Kongo- Central allows to describe the true facies of these rocks, the sedimentary model, the intrusions found and the cartographic consequences of all observations made in the region. The sedimentary rocks of Kimbungu massive have not been an object of a thorough survey or detailed. They have been mapped on the geological map of the region as being the low diamictit. The field work shows that it is not Diamictite but rather a shale. In fact, analyzes of this rock shows that it has a fine granulometry, a dark grey color and contain a high proportion in total carbon [> 5%]. It is almost composed of quartz angular to subangular forms swimming in clay or clay-micritic matrices and enclosed by pyrite. In the outcrop, some sedimentary structures of erosion and deposits are observed. This description corresponds to the one of shale. The characteristics described above and the extension of this shale suggest that it could have been deposited in a marine environment close to the coast with a possibility of enriching in carbonate and organic matter by the phenomenon of marine transgression. Doleritic intrusions were set up by tectonic activity [rifting] during the Middle Neoproterozoïc causing the sea transgression as well as the cleft volcanism. The Kimbungu massive is only occupied by the rocks with pelitic facies that we have described as the “shale”. This has led us to propose the modification of the geological map of Kimbungu region and its legend. Télécharger l'article