A high‐resolution multi‐proxy stalagmite record from Mechara,Southeastern Ethiopia: palaeohydrological implications for speleothem palaeoclimate reconstruction |
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| Authors: | Asfawossen Asrat Andy Baker Mohammed Umer Mohammed Melanie J Leng Peter Van Calsteren Claire Smith |
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| Institution: | 1. Department of Earth Sciences, Addis Ababa University, Addis Ababa, Ethiopia;2. School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, UK;3. NERC Isotope Geosciences Laboratory, British Geological Survey, Keyworth, Nottingham, UK and School of Geography, University of Nottingham, Nottingham, UK;4. OUUSF, Earth Sciences, The Open University, Milton Keynes, UK |
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| Abstract: | An annually laminated stalagmite from Southeastern Ethiopia grew for 443±8 yr starting at 5023 yr BP (±160 yr) as determined by lamina‐tuned U‐Th dating. The speleothem shows three growth phases: (1) an initial phase where the stalagmite has a candlestick shape, deposited by relatively slow rate drip water; (2) a middle growth phase where laminae grow on the flanks, suggesting faster drip rates; and (3) a final growth phase where the speleothem becomes narrower owing to a decrease in drip water supply towards the end of deposition. Morphometry, annual growth rate, fluorescence index, and 234U/238U isotope ratio show marked differences between the growth phases, while δ13C and δ18O do not show significant variation, except within the third phase towards the top of the stalagmite, where they have higher values. The study indicates that the multiproxy approach is crucial as the different proxies respond to single climate forcing in different manners. Our results can be widely applied to speleothem studies distinguishing the relative importance of the various proxies in recording cave ‘external’ (climate, hydrology) and cave ‘internal’ (e.g. evaporation) processes. Copyright © 2006 John Wiley & Sons, Ltd. |
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| Keywords: | stalagmite palaeoclimate palaeohydrology Holocene Ethiopia |
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