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Comment on “Radiocarbon calibration curve spanning 0 to 50,000 years BP based on paired 230Th/234U/238U and 14C dates on pristine corals” by R.G. Fairbanks et al. (Quaternary Science Reviews 24 (2005) 1781–1796)☆☆doi of original article: 10.1016/j.quascirev.2005.04.007 and “Extending the radiocarbon calibration beyond 26,000 years before present using fossil corals” by T.-C. Chiu et al. (Quaternary Science Reviews 24 (2005) 1797–1808)☆☆☆☆doi of original article: 10.1016/j.quascirev.2005.04.002

2006; Elsevier BV; Volume: 25; Issue: 7-8 Linguagem: Inglês

10.1016/j.quascirev.2005.09.009

1873-457X

Paula Reimer, Mike Baillie, Édouard Bard, J Warren Beck, Paul G. Blackwell, Caitlin E. Buck, George S. Burr, R. Lawrence Edwards, Michael Friedrich, T. P. Guilderson, Alan Hogg, Konrad A Hughen, Bernd Kromer, Gerry McCormac, Sturt W. Manning, Ron Reimer, John Southon, Minze Stuiver, J. van der Plicht, Constanze E. Weyhenmeyer,

Archaeology and ancient environmental studies

Multi-proxy high-resolution records relating to climate and dominant vegetation cover have been obtained from a peat deposit retrieved from the Kapsabet swamp in western Kenya. The 4-m long peat sequence provided a continuous sedimentation record spanning ca. 3023 cal yr BP to the present and is representative of the late Holocene changes in the relatively high-altitude part of the Lake Victoria catchment. Paleoenvironmental factors influencing peat formation and organic matter (OM) source inputs in Kapsabet were reconstructed based on total organic carbon, carbon accumulation rate, δ13C, δ15N, C/N ratio, and specific biomarker-based n-alkane ratios. The Kapsabet peat sequence was divided into five stages based on different climatic conditions: Stage 1 (3023–1670 cal yr BP) represents a progression from cool dry to wet conditions. Stage 2 (1670–1187 cal yr BP) is a relatively warm and wet period with increased productivity and high OM input. Stage 3 (1187–625 cal yr BP) represents gradual warming coeval to the late Holocene Medieval Warm Period. Stage 4 (625–188 cal yr BP) is a cool and wet period with high variability in precipitation and hydrological conditions representing the Little Ice Age. Stage 5 (188 cal yr BP to present) represents a relatively cool and wet period that coincides with the expansion of agriculture, particularly in the lowlands. The proxies indicate a progressive change from a forested landscape to an open woodland coeval to a decline in terrigenous inputs and the advent of more wet conditions. The climate on the highlands was less variable than in the lowlands, which underwent several periods of drought and intermittent wet conditions. The changes in the catchment coincided with the expansion of agriculture and land clearance marking increased human activities in the lowlands. Overall, the Kapsabet peat sequence tracks the regional climatic changes in East Africa and marks a promising sedimentary archive for palaeoclimate reconstruction from a region with a paucity of palaeoenvironmental and palaeovegetation histories.