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A 14,000-Year Oxygen Isotope Record from Diatom Silica in Two Alpine Lakes on Mt. Kenya
P. A. Barker,1F. A. Street-Perrott,2M. J. Leng,3P. B. Greenwood,3D. L. Swain,2*R. A. Perrott,2R. J. Telford,1K.
J. Ficken2
Oxygen isotopes are sensitive tracers of climate change in tropical
regions. Abrupt shifts of up to 18 per mil in the oxygenisotope ratio
of diatom silica have been found in a 14,000-yearrecord from two
alpine lakes on Mt. Kenya. Interpretation of tropical-montaneisotope
records is controversial, especially concerning the relativeroles of
precipitation and temperature. Here, we argue that Holocenevariations
in 18O are better explained by lake moisture balance
than by temperature-inducedfractionation. Episodes of heavy convective
precipitation dated~11,100 to 8600, 6700 to 5600, 2900 to 1900, and
<1300 years beforethe present were linked to enhanced soil erosion,
neoglacial iceadvances, and forest expansion on Mt. Kenya.
1 Hysed, Department of Geography, Lancaster
University, Lancaster LA1 4YB, UK.
2 Tropical
Palaeoenvironments Research Group, Department of Geography, University
of Wales Swansea, Swansea SA2 8PP, UK.
3 Natural
Environment Research Council (NERC) Isotope Geoscience Laboratory,
Keyworth, Nottingham NG12 5GG, UK.
*
Present address: Scottish Agricultural College, Crichton Royal
Farm, Dumfries DG1 4SZ, UK.
Present address: Department of Geography, University
of Newcastle, Newcastle-upon-Tyne NE1 7RU, UK.
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[DOI: 10.1126/science.1061940] |Summary »|Full Text »
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18O are better explained by lake moisture balance
than by temperature-induced fractionation. Episodes of heavy convective
precipitation dated ~11,100 to 8600, 6700 to 5600, 2900 to 1900, and
<1300 years before the present were linked to enhanced soil erosion,
neoglacial ice advances, and forest expansion on Mt. Kenya.
