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We present here the initial results of a high‐resolution (sparker) reflection seismic survey in Northern Lake Tanganyika, East African Rift system. We have combined these results with data from earlier multichannel reflection seismic and 5‐kHz echosounding surveys. The combination of the three complementary seismic investigation methods has allowed us to propose a new scenario for the late Aliocene to Recent sedimentary evolution of the North Tanganyika Basin. Seismic sequences and regional tectonic information permit us to deduce the palaeotopography at the end of each stratigraphic sequence. The basin history comprises six phases interpreted to be responses to variations in regional tectonism and/or climate. Using the reflection seismic‐radiocarbon method (RSRM), the minimum ages for the start of each phase (above each sequence boundary) are estimated to be: ?7.4 Ma, ? 1.1 Ma, ?393–363 ka, ?295–262 ka, ? 193–169 ka, ?40–35 ka. Corresponding lowstand lake elevations below present lake level for the last five phases are estimated to have been: ?650–700 m, ?350 m, ?350 m, ?250 m and ? 160 m, respectively. The latest phase from ?40–35 ka until the present can be subdivided into three subphases separated by two lowstand periods, dated at ?23 ka and ? 18 ka. From the late Miocene until the mid Pleistocene, large‐scale patterns of sedimentation within the basin were primarily controlled by tectonism. In contrast, from the mid Pleistocene to the present, sedimentation in Lake Tanganyika seems to have responded dramatically to climatic changes as suggested by repeated patterns of lake level fluctuations. During this period, the basin infill history is characterized by the recurrent association of three types of deposits: ‘basin fill’ accumulations; lens‐shaped ‘deep lacustrine fans’; and ‘sheet drape’ deposits. The successive low‐lake‐level fluctuations decreased in intensity with time as a consequence of rapid sedimentary filling under conditions of declining tectonic subsidence. The climate signal has thus been more pronounced in recent sedimentary phases as tectonic effects have waned.

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Travertine forming at Lorusio Hot Springs in the northern Kenya Rift is constructed mainly by lilypads and ledges. The lilypads are flat, accretionary structures rooted to the substrate that are composed mostly of platy calcite crystals. They grow outward from a nucleus, subparallel to the water surface, at or just below the air-water interface. Precipitation results from rapid degassing of CO2. Ledges, which have a similar morphology and internal structure, are attached to the margin of a spring pool or outflow channel. As they grow laterally, lilypads and ledges may coalesce with their neighbours to produce thin (1-3 cm) beds of travertine, examples of which are exposed in subfossil deposits at the site. Once established, lilypads and ledges modify the outflow and can act as substrates for precipitation of other minerals and colonization by microbes on their cooler subaerial surfaces. Pore fluids are drawn upward through the lilypads by capillary evaporation. Amorphous silica then precipitates as surficial crusts upon microbial mats or forms spicular microstromatolites, some of which also contain calcite laminae. Efflorescent Na-CO3 salts commonly encrust the drier central platforms of the exposed lilypad. The unusual abundance of lilypads and ledges at Lorusio reflects (i) the low-relief setting and the hydrostatic head, which limit terrace development, and (ii) the high temperature (>75°C) of the waters, which inhibits colonization by microbial mats at crystal growth sites. Similar structures form in cave pools, evaporating brines, and freezing water at sites where precipitation is induced by several processes active at the air-water interface.

The Tanganyika continental rift basin is one of the most important structural features of the East African rift system and provides an opportunity to observe the early stages of rift basin development unobscured by postrift deformation and erosion. The geometry of half grabens and their zones of linkage have a great influence on rift development and depositional environments. Topographic features associated with zones of linkage between half grabens exert a direct control on drainage basin evolution, sediment supply, and synrift stratigraphy. Previous structural studies, based on widely spaced (ϳ15 km) seismic reflection profiles, focused mainly on large-scale geometrical fault descriptions and not on the spatial and temporal linkage of the individual border faults controlling each half graben. In this article, using newly available basin age estimates, multichannel seismic reflection data, high-resolution single-channel sparker seismic data, and onshore structural data (remote directioning and microstructural field observations), we have constructed a detailed late Miocene-Holocene kinematic model for the evolution of the northern part of the Lake Tanganyika rift basin. A classification of fault interaction geometry is proposed to describe the initiation and development through time of major depocenters. Fault correlation lessons are provided for exploration seismic interpreters in extensional settings. The development of the depocenters of northern Lake Tanganyika is complex, and this article clearly shows that antecedent structures control subbasin initiation and development. As the rift evolves, border faults become dominant, producing more