A 12 m piston core (LT 84-8P) taken in the northern basin of Lake Turkana has been dated by 6 AMS radiocarbon dates on large ostracods and analysed for its pollen content. During the past 2500 years, the pollen assemblages were dominated by Chenopodiaceae/Amaranthaceae (Cheno/Am) and Gramineae, representing the local pollen signal of the surrounding vegetation under arid conditions. Percentage fluctuations of Cheno/Am are interpreted as reflecting lake level variations in good correspondance with oxygen isotope from the same core. A rise in lake level is recorded at about 1600 yr B.P., preceded by a relative lowstand during much of the period from 2500 to 1600 yr B.P. The top of the core is estimated to be about 600 yr old, and shows a shift of unknown duration towards a more humid condition. The high lake level documented in this paper roughly coincides with that reconstructed from other cores in the lake based on diatom and carbonate analyses.
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We thank H. Hooghiemstraf or invaluable improvemenotf the manuscriptG, uy Riollet and Guillaume Buchet for assistancein processing samplesa nd pollen identificationN,i cole Page for helping.W e acknowledgJeo hn Halfmana nd Guy Lister for recoveringc ore LT84-89 from Lake Turkana in 1984 as part of Project PROBE of Duke University,f unded by' NSF Grant ATM 9104730a nd NOAA Grant NA 36 PF 0317 to T.C. Johnson, under permissionb y the Kenyan Governmenfto r access to Lake Turkana. This researchw asf undedb y FrenchM inistryo f Foreign Affairs (Grant to R. Bonnefille)w hich provided funds for MohammedU mer'sPhD program in France and by CNRS (PNEDC Palaeoclimate Program).
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