Barker, Philip A. and Hurrell, Elizabeth R. and Leng, Melanie J. and Wolff, Christian and Cocquyt, Christine and Sloane, Hilary J. and Verschuren, Dirk (2011) Seasonality in equatorial climate over the past 25 k.y. revealed by oxygen isotope records from Mount Kilimanjaro. Geology, 39 (12). pp. 1111-1114. ISSN 1943-2682Full text not available from this repository.
Multiproxy analysis of a well-dated 25 ka lake sediment sequence from Lake Challa, on the eastern flank of Mount Kilimanjaro (East Africa), reveals the climatic controls that govern both the lake's paleohydrology and the climate-proxy record contained in the mountain's receding ice cap. The oxygen isotope record extracted from diatom silica (delta(18)O(diatom)) in Lake Challa sediments captured dry conditions during the last glacial period and a wet late-glacial transition to the Holocene interrupted by Younger Dryas drought. Further, it faithfully traced gradual weakening of the southeastern monsoon during the Holocene. Overall, delta(18)O(diatom) matches the branched isoprenoid tetraether (BIT) index of rainfall-induced soil runoff, except during 25-22 ka and the past 5 k.y. when insolation forcing due to orbital precession enhanced the northeastern monsoon. This pattern arises because during these two periods, a weakened southeastern monsoon reduced the amount of rainfall during the long rainy season and enhanced the opposing effect of evaporation intensity and/or length of the austral winter dry season. Importantly, our lake-based reconstruction of moisture-balance seasonality in equatorial East Africa also helps us understand the oxygen isotope record contained in Mount Kilimanjaro ice. Negative correlation between ice core delta(18)O and Lake Challa delta(18)O(diatom) implies that moisture balance is not the primary climate control on the long-term trend in ice core delta(18)O.
|Journal or Publication Title:||Geology|
|Additional Information:||Dec Seasonality in equatorial climate over the past 25 k.y. revealed by oxygen isotope records from Mount Kilimanjaro Times Cited: 0|
|Subjects:||G Geography. Anthropology. Recreation > GE Environmental Sciences|
|Departments:||Faculty of Science and Technology > Lancaster Environment Centre|
|Deposited On:||16 Mar 2012 15:40|
|Last Modified:||24 Jun 2016 01:40|
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