TY  - JOUR
A1  - Wichura, Henry
A1  - Bousquet, Romain
A1  - Oberhänsli, Roland
A1  - Strecker, Manfred
A1  - Trauth, Martin H.
T1  - Evidence for middleUocene uplift of the East African Plateau
N2  - Cenozoic uplift of the East African Plateau has been associated with fundamental climatic and environmental changes in East Africa and adjacent regions. While this influence is widely accepted, the timing and the magnitude of plateau uplift have remained unclear. This uncertainty stems from the lack of datable, geomorphically meaningful reference horizons that could record surface uplift. Here, we document the existence of significant relief along the East African Plateau prior to rifting, as inferred from modeling the emplacement history of one of the longest terrestrial lava flows, the similar to 300-km-long Yatta phonolite flow in Kenya. This 13.5 Ma lava flow originated on the present-day eastern Kenya Rift flank, and utilized a riverbed that once routed runoff from the eastern rim of the plateau. Combining an empirical viscosity model with subsequent cooling and using the Yatta lava flow geometry and underlying paleotopography (slope angle), we found that the prerift slope was at least 0.2 degrees, suggesting that the lava flow originated at a minimum elevation of 1400 m. Hence, high paleotopography in the Kenya Rift region must have existed by at least 13.5 Ma. We infer from this that middle Miocene uplift occurred, which coincides with the two-step expansion of grasslands, as well as important radiation and speciation events in tropical Africa.
Y1  - 2010
UR  - http://geology.gsapubs.org/
U6  - https://doi.org/10.1130/G31022.1
SN  - 0091-7613
ER  - 
TY  - JOUR
A1  - Trauth, Martin H.
A1  - Maslin, Mark A.
A1  - Deino, Alan L.
A1  - Junginger, Annett
A1  - Lesoloyia, Moses
A1  - Odada, Eric O.
A1  - Olago, Daniel O.
A1  - Olaka, Lydia A.
A1  - Strecker, Manfred
A1  - Tiedemann, Ralph
T1  - Human evolution in a variable environment : the amplifier lakes of Eastern Africa
N2  - The development of rise Cenozoic East African Rift System (EARS) profoundly re-shaped the landscape and significantly increased the amplitude of short-term environmental response to climate variation. In particular, the development of amplifier lakes in rift basins after three million years ago significantly contributed to this exceptional sensitivity of East Africa to climate change compared to elsewhere on the African continent. Amplifier lakes are characterized by tectonically-formed graben morphologies in combination with an extreme contrast between high precipitation in the elevated parts of the catchment and high evaporation in the lake area. Such amplifier lakes respond rapidly to moderate, precessional-forced climate shifts, and as they do so apply dramatic environmental pressure to the biosphere. Rift basins, when either extremely dry or lake-filled, form important barriers for migration, mixing and competition of different populations of animals and hominins. Amplifier lakes link long-term, high-amplitude tectonic processes and short-term environmental fluctuations. East Africa may have become the place where early humans evolved as a consequence of this strong link between different time scales. (C) 2010 Elsevier Ltd. All rights reserved.
Y1  - 2010
UR  - http://www.sciencedirect.com/science/journal/02773791
U6  - https://doi.org/10.1016/j.quascirev.2010.07.007
SN  - 0277-3791
ER  - 
TY  - JOUR
A1  - Epp, Laura Saskia
A1  - Stoof, Kathleen R.
A1  - Trauth, Martin H.
A1  - Tiedemann, Ralph
T1  - Historical genetics on a sediment core from a Kenyan lake : intraspecific genotype turnover in a tropical rotifer is related to past environmental changes
N2  - Using molecular genetic methods and an ancient DNA approach, we studied population and species succession of rotifers of the genus Brachionus in the Kenyan alkaline-saline crater lake Sonachi since the beginning of the 19th century as well as distribution of Brachionus haplotypes in recent and historic sediments of other lakes of the East African Rift System. The sediment core record of Lake Sonachi displays haplotypes of a distinct evolutionary lineage in all increments. Populations were dominated by a single mitochondrial haplotype for a period of 150 years, and two putatively intraspecific turnovers in dominance occurred. Both changes are concordant with major environmental perturbations documented by a profound visible change in sediment composition of the core. The first change was very abrupt and occurred after the deposition of volcanic ash at the beginning of the 19th century. The second change coincides with a major lake level lowstand during the 1940s. It was preceded by a period of successively declining lake level, in which two other haplotypes appeared in the lake. One of these putatively belongs to another species documented in historical and recent Kenyan lake sediments. The analysis of plankton population dynamics through historical time can reveal patterns of population persistence and turnover in relation to environmental changes.
Y1  - 2010
UR  - http://www.springerlink.com/content/100294
U6  - https://doi.org/10.1007/s10933-009-9379-7
SN  - 0921-2728
ER  -