Morphotectonic evolution of the central Kenya rift flanks: Implications for late Cenozoic environmental change in East Africa

Geology ◽  
2007 ◽  
Vol 35 (5) ◽  
pp. 427 ◽  
Author(s):  
Cornelia Spiegel ◽  
Barry P. Kohn ◽  
David X. Belton ◽  
Andrew J.W. Gleadow
Keyword(s):  
Environmental Change ◽  
East Africa ◽  
Late Cenozoic ◽  
Kenya Rift ◽  
Morphotectonic Evolution ◽  
Central Kenya

Tectonic and climatic control on evolution of rift lakes in the Central Kenya Rift, East Africa

2009 ◽  
Vol 28 (25-26) ◽  
pp. 2804-2816 ◽  
Author(s):  
A.G.N. Bergner ◽  
M.R. Strecker ◽  
M.H. Trauth ◽  
A. Deino ◽  
F. Gasse ◽  
...  
Keyword(s):  
East Africa ◽  
Kenya Rift ◽  
Climatic Control ◽  
Central Kenya

Middle–late Miocene palaeoenvironments, palynological data and a fossil fish Lagerstätte from the Central Kenya Rift (East Africa)

2015 ◽  
Vol 154 (1) ◽  
pp. 24-56 ◽  
Author(s):  
CORNELIA RASMUSSEN ◽  
BETTINA REICHENBACHER ◽  
OLAF LENZ ◽  
MELANIE ALTNER ◽  
STEFANIE B. R. PENK ◽  
...  
Keyword(s):  
East Africa ◽  
Late Miocene ◽  
Explosive Volcanism ◽  
Tectonic Activity ◽  
Rift System ◽  
East African Rift System ◽  
Kenya Rift ◽  
Alkaline Lakes ◽  
Palynological Data ◽  
Central Kenya

AbstractThe Miocene epoch was a time of major change in the East African Rift System (EARS) as forest habitats were transformed into grasslands and hominids appeared in the landscape. Here we provide new sedimentological and palynological data on the middle–upper Miocene Ngorora Formation (Tugen Hills, Central Kenya Rift, EARS), together with clay mineral characterizations, mammal finds and a description of the Ngorora fish Lagerstätte. Furthermore, we introduce a revised age ofc. 13.3 Ma for the onset of the Ngorora Formation. The older part of the Ngorora Formation (c. 13.3–12 Ma) records low-energy settings of lakes, floodplains and palaeosols, and evidence of analcime indicates that lakes were alkaline. The palynomorph spectrum consists of tree pollen (Juniperus, Podocarpus), Euphorbiaceae pollen (Acalypha, Croton) and herbaceous pollen of Poaceae and Asteraceae, suggestive of wooded grasslands or grassy woodlands. Alkaline lakes, floodplains and palaeosols continue upsection (c. 12–9 Ma), but environmental fluctuations become more dynamic. Paucity of palynomorphs and the presence of an equid may point to progressively drier conditions. A total of about 500 articulated fish fossils were recovered from distinctive layers of almost all sections studied and represent different lineages of the Haplotilapiines (Pseudocrenilabrinae, Cichlidae). Some of the fish kills may be attributable to rapid water acidification and/or asphyxiation by episodic ash falls. Repeated instances of abrupt change in water depth in many sections are more likely to be due to synsedimentary tectonic activity of the Central Kenya Rift than to climatic variation. Overall, the preservation of the Ngorora fish Lagerstätte resulted from the interplay of tectonics, formation of alkaline lakes and explosive volcanism. As records of grasslands that pre-date late Miocene time are rare, our finding of middle Miocene (12–13 Ma) grassy savannah in the Central Kenya Rift is also relevant to models of human evolution in East Africa.

The Potassium-Argon Dating of Late Cenozoic Rocks in East Africa and Italy [and Comments and Reply]

1965 ◽  
Vol 6 (4) ◽  
pp. 342-385 ◽  
Author(s):  
J. F. Evernden ◽  
G. H. Curtis ◽  
William Bishop ◽  
C. Loring Brace ◽  
J. Desmond Clark ◽  
...  
Keyword(s):  
East Africa ◽  
Late Cenozoic ◽  
Argon Dating

scholarly journals Expressions of climate perturbations in western Ugandan crater lake sediment records during the last 1000 yr

2013 ◽  
Vol 9 (5) ◽  
pp. 5183-5226 ◽  
Author(s):  
K. Mills ◽  
D. B. Ryves ◽  
N. J. Anderson ◽  
C. L. Bryant ◽  
J. J. Tyler
Keyword(s):  
Environmental Change ◽  
East Africa ◽  
Environmental Changes ◽  
Sediment Cores ◽  
Ice Age ◽  
Ecosystem Response ◽  
Large Lakes ◽  
Crater Lakes ◽  
Continental Scale ◽  
Western Uganda

Abstract. Equatorial East Africa has a complex, regional patchwork of climate regimes, with multiple interacting drivers. Recent studies have focussed on large lakes and reveal signals that are smoothed in both space and time, and, whilst useful at a continental scale, are of less relevance when understanding short-term, abrupt or immediate impacts of climate and environmental changes. Smaller-scale studies have highlighted spatial complexity and regional heterogeneity of tropical palaeoenvironments in terms of responses to climatic forcing (e.g. the Little Ice Age [LIA]) and questions remain over the spatial extent and synchroneity of climatic changes seen in East African records. Sediment cores from paired crater lakes in western Uganda were examined to assess ecosystem response to long-term climate and environmental change as well as testing responses to multiple drivers using redundancy analysis. These archives provide annual to sub-decadal records of environmental change. The records from the two lakes demonstrate an individualistic response to external (e.g. climatic) drivers, however, some of the broader patterns observed across East Africa suggest that the lakes are indeed sensitive to climatic perturbations such as a dry Mediaeval Climate Anomaly (MCA; 1000–1200 AD) and a relatively drier climate during the main phase of the LIA (1500–1800 AD); though lake levels in western Uganda do fluctuate. The relationship of Ugandan lakes to regional climate drivers breaks down c. 1800 AD, when major changes in the ecosystems appear to be a response to sediment and nutrient influxes as a result of increasing cultural impacts within the lake catchments. The data highlight the complexity of individual lake response to climate forcing, indicating shifting drivers through time. This research also highlights the importance of using multi-lake studies within a landscape to allow for rigorous testing of climate reconstructions, forcing and ecosystem response.

Geochemical evidence of hydrothermal recharge in Lake Baringo, central Kenya Rift Valley

2006 ◽  
Vol 20 (9) ◽  
pp. 2027-2055 ◽  
Author(s):  
Corinne Tarits ◽  
Robin W. Renaut ◽  
Jean-Jacques Tiercelin ◽  
Alain Le Hérissé ◽  
Jo Cotten ◽  
...  
Keyword(s):  
Rift Valley ◽  
Kenya Rift ◽  
Geochemical Evidence ◽  
Central Kenya ◽  
Kenya Rift Valley
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