Past environmental and climatic changes during the last 7200 cal yr BP in Adamawa plateau (Northern-Cameroun) based on fossil diatoms and sedimentary carbon isotopic records from Lake Mbalang

Nguetsop, Victor François; Bentaleb, I.; Favier, Charly; Martin, Céline; Bietrix, Sophie; Giresse, Pierre; Servant-Vildary, Simone; Servant, Michel

doi:10.5194/cp-7-1371-2011

Cited by 22 publications

(9 citation statements)

References 50 publications

(72 reference statements)

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“…2000 yr BP and ca. 1000 yr BP indicated by low percentages of planktonic diatoms in the EJ1 core and high δ 18 O in the Bosumtwi record have also been reported from Cameroonian volcanic crater lakes Barombi Mbo (Giresse et al, 1994; Lebamba et al, 2012), Mbalang, and Ossa (Nguetsop et al, 2010, 2011). We therefore consider it probable that hydroclimates at Ejagham were similar to those elsewhere in the West African summer monsoon region during the early Holocene as well.…”

Section: Discussionmentioning

confidence: 69%

On the Age and Origin of Lake Ejagham, Cameroon, and Its Endemic Fishes

et al. 2017

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Lake Ejagham is a small, shallow lake in Cameroon, West Africa, which supports five endemic species of cichlid fishes in two distinct lineages. Genetic evidence suggests a relatively young age for the species flocks, but supporting geologic evidence has thus far been unavailable. Here we present diatom, geochemical, mineralogical, and radiocarbon data from two sediment cores that provide new insights into the age and origin of Lake Ejagham and its endemic fishes. Radiocarbon ages at the base of the longer core indicate that the lake formed approximately 9 ka ago, and the diatom record of the shorter core suggests that hydroclimate variability during the last 3 millennia was similar to that of other lakes in Cameroon and Ghana. These findings establish a maximum age of ca. 9 cal ka BP for the lake and its endemic species and suggest that repeated cichlid speciation in two distinct lineages occurred rapidly within the lake. Local geology and West African paleoclimate records argue against a volcanic, chemical, or climatic origin for Lake Ejagham. Although not conclusive, the morphometry of the lake and possible signs of impact-induced effects on quartz grains are instead more suggestive of a bolide impact.

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Section: Discussionmentioning

confidence: 69%

On the Age and Origin of Lake Ejagham, Cameroon, and Its Endemic Fishes

et al. 2017

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“…event observed in compiled North African lake records (6), whereas the age cluster starting at 6.6 ka is consistent with the end of the 6.6-ka dry event (6). The cluster of ages between 6.6 and 5.0 ka include a shoreline at 308 m (CH46, 6.0 ± 0.3 ka), which may indicate a brief fall in lake level, consistent with evidence for aridity in nearby regions at this time (33,34).…”

Section: West African Monsoon Dynamicsmentioning

confidence: 67%

West African monsoon dynamics inferred from abrupt fluctuations of Lake Mega-Chad

Armitage

Bristow

Drake

2015

Proc. Natl. Acad. Sci. U.S.A.

129

116

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From the deglacial period to the mid-Holocene, North Africa was characterized by much wetter conditions than today. The broad timing of this period, termed the African Humid Period, is well known. However, the rapidity of the onset and termination of the African Humid Period are contested, with strong evidence for both abrupt and gradual change. We use optically stimulated luminescence dating of dunes, shorelines, and fluviolacustrine deposits to reconstruct the fluctuations of Lake Mega-Chad, which was the largest pluvial lake in Africa. Humid conditions first occur at ∼15 ka, and by 11.5 ka, Lake Mega-Chad had reached a highstand, which persisted until 5.0 ka. Lake levels fell rapidly at ∼5 ka, indicating abrupt aridification across the entire Lake Mega-Chad Basin. This record provides strong terrestrial evidence that the African Humid Period ended abruptly, supporting the hypothesis that the African monsoon responds to insolation forcing in a markedly nonlinear manner. In addition, Lake Mega-Chad exerts strong control on global biogeochemical cycles because the northern (Bodélé) basin is currently the world’s greatest single dust source and possibly an important source of limiting nutrients for both the Amazon Basin and equatorial Atlantic. However, we demonstrate that the final desiccation of the Bodélé Basin occurred around 1 ka. Consequently, the present-day mode and scale of dust production from the Bodélé Basin cannot have occurred before 1 ka, suggesting that its role in fertilizing marine and terrestrial ecosystems is either overstated or geologically recent.

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“…At nearby Lake Mbalang, a corresponding lowstand is centred on c. 550 CE (Nguetsop et al, 2011). The timing of these transitions is more or less synchronous with the drying inferred at Kajemarum Oasis.…”

mentioning

confidence: 72%

African hydroclimatic variability during the last 2000 years

Nash

Cort

Chase

et al. 2016

Quaternary Science Reviews

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The African continent is characterised by a wide range of hydroclimate regimes, ranging from humid equatorial West Africa to the arid deserts in the northern and southern subtropics. The livelihoods of much of its population are also vulnerable to future climate change, mainly through variability in rainfall affecting water resource availability. A growing number of data sources indicate that such hydroclimatic variability is an intrinsic component of Africa's natural environment. This paper, co-authored by members of the PAGES Africa 2k Working Group, presents an extensive assessment and discussion of proxy, historical and instrumental evidence for hydroclimatic variability across the African continent, spanning the last two millennia. While the African palaeoenvironmental record is characterised by spatially disjunctive datasets, with often less-than-optimal temporal resolution and chronological control, the available evidence allows the assessment of prominent spatial patterns of palaeomoisture variability through time. In this study, we focus sequentially on data for six major time windows: the first millennium AD, the Medieval Climate Anomaly (900-1250 CE), the Little Ice Age (1250-1750 CE), the end of the LIA (1750-1850 CE), the Early Modern Period , and the period of recent warming (1950 onwards). This results in a continentwide synthesis of regional moisture-balance trends through history, allowing consideration of possible driving mechanisms, and suggestions for future research.

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Past environmental and climatic changes during the last 7200 cal yr BP in Adamawa plateau (Northern-Cameroun) based on fossil diatoms and sedimentary carbon isotopic records from Lake Mbalang

Cited by 22 publications

References 50 publications

On the Age and Origin of Lake Ejagham, Cameroon, and Its Endemic Fishes

On the Age and Origin of Lake Ejagham, Cameroon, and Its Endemic Fishes

West African monsoon dynamics inferred from abrupt fluctuations of Lake Mega-Chad

African hydroclimatic variability during the last 2000 years

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