ABSTRACT
A first interpretation of a new grid of high-resolution reflection seismic profiles has revealed new insights in the sequence stratigraphic and structural framework of Livingstone Basin (northernmost Lake Malawi). Seven seismic sequences could be identified and were tentatively correlated with the Songwe and Mbamba Sequences of Pleistocene–Recent age. The acoustic substrate is interpreted to represent the top of the Nyasa/Baobab Sequence, correlative with the African Two Geomorphological Surface. The stacking pattern of the seven sequences represents a complete long-term lake level cycle, from a lake lowstand at appr. 320 m below the present level to the present-day lake highstand. Higher-frequency lake level oscillations controlled the succession of sedimentary facies within each of the sequences, which sometimes show classical passive-margin type sequence stratigraphic architectures. The observed structural features show evidence of a strongly variable tectonic behaviour. Some faults appear to be presently active and strongly influence the lake floor morphology, while the activity of others seems to have stopped a various stages throughout the Pleistocene. Large-scale tectonic movements, such as along the Livingstone Border Fault, have to a certain extent exerted an influence on the distribution of the sedimentary facies, as witnessed by the northward migration of the North-Kiwira delta lobes.
