Lake Baringo, Kenya Rift Valley, and its Pleistocene Precursors

• Autores: Robin Renaut, Jean-Jacques Tiercelin, R. Bernhart Owen
• Localización: Lake basins through space and time / coord. por Elizabeth H. Gierlowski-Kordesch, K. Kelts, 2000, ISBN 0891810528, págs. 561-568
• Idioma: inglés
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• Resumen

  • Lake Baringo is a shallow freshwater lake with predominantly siliciclastic sediments that is located in asemi-arid volcanic region of the central Kenya RiftValley (Figure lA, B) (Tiercelin and Vincens, 1987).The modern lake is the successor to a series of precursorlakes that have occupied the rift valley at this latitude(ION) since the middle Miocene (Bishop et aI.,1971; Chapman et aI., 1978; Tiercelin, 1981; Hill, 1995,1999; Renaut et aI., 1999). Lake Baringo lies in the northern part of a rhomb-shaped half-graben basin,approximately 21 km long by 13 km wide. The shape of the lake and the basin morphology are controlled mainly by two regional tectonic trends-the north-southtrend of the Tertiary to Holocene rift system, and a group of older northwest-southeast lineaments inherited from the Precambrian basement (Figure IC) (Dunkleyet aI., 1993; Le Turdu et aI., 1995, in press). The intersection of these two tectonic trends not only influences the patterns of drainage and sedimentation, but also has played a major role in controlling the recurrence of lake basins at this latitude. Rooney and Hutton (1977)showed from geophysical data that more than 1 km of sediments underlies the present lake basin. New geophysicalevidence indicates that modern Lake Baringo and the Loboi Plain (Figure 1C) are the surface expression of a deep (more than 5 km) fault-controlled basinthat was probably initiated during the Paleogene (Hautotet aI., 1998, personal communication).West of the lake, the land rises 1500 m above the riftfloor to form the Tugen Hills, a large intrarift faultblock composed of Neogene lavas and sedimentaryrocks