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

Bergner, Andreas G.N.; Strecker, Manfred R.; Trauth, Martin H.; Deino, Alan L.; Gasse, Françoise; Blisniuk, Peter M.; Dühnforth, Miriam

doi:10.1016/j.quascirev.2009.07.008

Cited by 83 publications

(37 citation statements)

References 60 publications

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“…In Kenya, moisture transport and precipitation associated with the Intertropical Convergence Zone and the Congo Air Boundary are modulated by the East African Plateau, the rift shoulders, and high evapotranspiration (Nicholson, 1996;Bergner et al, 2009). The Suguta Valley is one of the driest regions of Kenya, with 300 to 500 mm yr −1 precipitation, ephemeral runoff (Ojany and Ogenoo, 1973), and sparse vegetation.…”

Section: Geology and Climate Of The Northern Kenya Riftmentioning

confidence: 99%

“…kyr BP: (1) pollen spectra and carbon and hydrogen isotopes measured in plant leaf-waxes document shifts in the dominance of forests/woodlands versus grasslands following shifts in rainfall (Kendall, 1969;Tierney et al, 2010); (2) lacustrine sediments record oscillating lakes with co-varying changes in water chemistry and biota, reflecting alternating wetter and drier periods (Richardson and Dussinger, 1986;Bergner et al, 2009; data. Also shown is a contour at ∼567 m indicating the maximum extent of the paleo-Lake Suguta (MHS, white line; after Garcin et al, 2009), quartz-bearing areas within the Baragoi Basin, which represent 42% of the total catchment area (transparent layer; after BEICIP, 1987), and areas prone to gullying derived from the analysis of high-resolution satellite images.…”

Section: Introductionmentioning

confidence: 99%

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Short-lived increase in erosion during the African Humid Period: Evidence from the northern Kenya Rift

Garcin

Schildgen

Acosta

et al. 2017

Earth and Planetary Science Letters

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The African Humid Period (AHP) between ∼15 and 5.5 cal. kyr BP caused major environmental change in East Africa, including filling of the Suguta Valley in the northern Kenya Rift with an extensive (∼2150 km 2 ), deep (∼300 m) lake. Interfingering fluvio-lacustrine deposits of the Baragoi paleo-delta provide insights into the lake-level history and how erosion rates changed during this time, as revealed by delta-volume estimates and the concentration of cosmogenic 10 Be in fluvial sand. Erosion rates derived from delta-volume estimates range from 0.019 to 0.03 mm yr −1 . 10 Be-derived paleo-erosion rates at ∼11.8 cal. kyr BP ranged from 0.035 to 0.086 mm yr −1 , and were 2.7 to 6.6 times faster than at present. In contrast, at ∼8.7 cal. kyr BP, erosion rates were only 1.8 times faster than at present. Because 10 Bederived erosion rates integrate over several millennia, we modeled the erosion-rate history that best explains the 10 Be data using established non-linear equations that describe in situ cosmogenic isotope production and decay. Two models with different temporal constraints (15-6.7 and 12-6.7 kyr) suggest erosion rates that were ∼25 to ∼300 times higher than the initial erosion rate (pre-delta formation). That pulse of high erosion rates was short (∼4 kyr or less) and must have been followed by a rapid decrease in rates while climate remained humid to reach the modern 10 Be-based erosion rate of ∼0.013 mm yr −1 .Our simulations also flag the two highest 10 Be-derived erosion rates at ∼11.8 kyr BP related to nonuniform catchment erosion. These changes in erosion rates and processes during the AHP may reflect a strong increase in precipitation, runoff, and erosivity at the arid-to-humid transition either at ∼15 or ∼12 cal. kyr BP, before the landscape stabilized again, possibly due to increased soil production and denser vegetation.

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Section: Geology and Climate Of The Northern Kenya Riftmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Short-lived increase in erosion during the African Humid Period: Evidence from the northern Kenya Rift

Garcin

Schildgen

Acosta

et al. 2017

Earth and Planetary Science Letters

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“…All radiocarbon ages corroborate other studies of lake level fluctuations along the EARS. For the Nakuru-Elmenteita and the Naivasha Basin high lake level stands were postulated for the periods 146,000 to 73,300 y BP and 15,200 to 9600 y BP [1,49]. Trauth et al [7] studied the nearby Ol Njorowa Gorge where they detected high level stands at 146,000 to 141,000 y BP and ca.…”

Section: Study Area and Paleolake Evidencementioning

confidence: 99%

“…Many authors have used lakes as indicators for climate and landscape changes in the Quaternary [1][2][3][4][5][6]. Lakes associated with the East African Rift System (EARS) respond in a quite sensitive way to tectonic and climatic changes [1].…”

Section: Introductionmentioning

confidence: 99%

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The Delineation of Paleo-Shorelines in the Lake Manyara Basin Using TerraSAR-X Data

2014

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Abstract:The purpose of this paper is to describe the delineation of paleo-shorelines using high resolution microwave images and digital image processing tools, and with that to contribute to the understanding of the complex landscape evolution of the Lake Manyara Basin. The surroundings of Lake Manyara are the focus of several paleo-archeological investigations, since the location is close to Olduvai Gorge, where paleo-anthropological findings can be traced back to homo habilis. In the catchment of Lake Manyara two hominin-bearing sites (0.78 to 0.63 Ma), lots of vertebrate fossils and hand axes from different periods were found. Understanding the development and extent of the lake is crucial for understanding the regional paleo-environment of the Quaternary. Morphological structures of shorelines and terraces east of Lake Manyara were identified from TerraSAR-X StripMap images. By applying a Canny edge detector, linear features were extracted and revised for different image acquisitions using a contextual approach. Those features match literature and field references. A digital elevation model of the region was used to map the most distinct paleo-shorelines according to their elevation.

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Climate Change, Lacustrine Zone

Wright¹

2021

The Encyclopedia of Ancient History

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Due to its position in the trough of the East African Rift Valley, the Great Lakes region has experienced significant effects from changes to earth's climate during the Holocene. Annually migrating atmospheric pressure systems bring oceanic moisture inland, causing precipitation mainly in the highlands that charges groundwater systems in the lowlands. Although the Holocene has been a relatively stable climatic epoch for most of the planet, the lacustrine region of eastern Africa has experienced significant hydrologic variability. The African Humid Period brought significantly higher rainfall to the northern two‐thirds of the continent, including most of the lacustrine zone, but had a minimal impact on lake levels in the southern aspect of the region. Lake records show that after 2000 bce the northern region experienced lower average precipitation while lake levels rose on balance across the southern region. However, high‐resolution records consistently demonstrate that there is significant variability in the tempo and spatial application of precipitation and vegetation in East African lakes. Additionally, since the advent of the Common Era, there are increasingly obvious impacts of human landscape disturbance on the region's ecology, affecting lake levels and biodiversity.

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

Cited by 83 publications

References 60 publications

Short-lived increase in erosion during the African Humid Period: Evidence from the northern Kenya Rift

Short-lived increase in erosion during the African Humid Period: Evidence from the northern Kenya Rift

The Delineation of Paleo-Shorelines in the Lake Manyara Basin Using TerraSAR-X Data

Climate Change, Lacustrine Zone

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