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Beschrijving
Klerkx, J., Theunissen, K. & Delvaux, D. 1998. ‘Persistent fault controlled basin formation since the Proterozoic along the western branch of the East African Rift’. Delvaux, D. and Khan, A (eds), Journal of African Earth Sciences 26(3), special issue : Tectonics, sedimentation and volcanism in the East African Rift System : 347-361. Elsevier. I.F. 1.219.
Article in a scientific Journal / Article in a Journal
The western branch of the East African Rift system is outlined by elongate sedimentary basins, frequently occupied by Cenozoic rift lakes. The role of the inheritance of the leading rift faults from pre-existing basement structures often has been invoked. Recent studies in western Tanzania confirm to what extent the NW oriented Paleoproterozoic Ubende belt contributed to the Phanerozoic rift. Attention is drawn here on the occurrence of different Meso- and Neoproterozoic sedimentary basins that developed along the ductile shear belt as a result of its repeated sinistral wrench fault reactivation. These basins partly overlap each other and typically bear shallow level and weakly evolved sediments. North of the Ubende belt, the Mesoproterozoic Kibara belt is inferred to have originated as a basin controlled by the complex termination of the Ubende wrench fault.
Phanerozoic rift basins also develop along the NW oriented Ubende belt structure. They display the same elongate shape as the Proterozoic basins. In Late Paleozoic - Early Mesozoic (Karoo), they result from a dextral lateral shear reactivation of the inherited Proterozoic shear faults. During the first phase of its development the Tanganyika basin is believed to bear the same characteristics as all previous basins, which developed along the Ubende shear belt, mainly controlled by strike-slip movements along preexisting shear faults. The present Tanganyika basin issubdivided in two sub-basins, separated by the transverse Mahali shoal, which is an active structure located on the Ubende shear. The deep lake basin mainly developed outside the Ubende belt. The northern sub-basin appears to be structurally controlled by the reactivation of the Mesoproterozoic sinistral wrench fault termination of the Ubende shear faults. Structural control of the Paleoproterozoic basement is however unclear for the southern sub-basin of Lake Tanganyika: this part of the rift segment is flanked by Paleoproterozoic basement which has not been affected by the Ubende shear.