Seasonality in equatorial climate over the past 25 k.y. revealed by oxygen isotope records from Mount Kilimanjaro
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. Th...
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Online Access: | https://eprints.lancs.ac.uk/id/eprint/53140/ https://doi.org/10.1130/G32419.1 |
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ftulancaster:oai:eprints.lancs.ac.uk:53140 2023-08-27T04:09:58+02:00 Seasonality in equatorial climate over the past 25 k.y. revealed by oxygen isotope records from Mount Kilimanjaro Barker, Philip A. Hurrell, Elizabeth R. Leng, Melanie J. Wolff, Christian Cocquyt, Christine Sloane, Hilary J. Verschuren, Dirk 2011-12 https://eprints.lancs.ac.uk/id/eprint/53140/ https://doi.org/10.1130/G32419.1 unknown 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 1943-2682 Journal Article PeerReviewed 2011 ftulancaster https://doi.org/10.1130/G32419.1 2023-08-03T22:21:54Z 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. Article in Journal/Newspaper Ice cap ice core Lancaster University: Lancaster Eprints Austral Geology 39 12 1111 1114 |
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Open Polar |
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Lancaster University: Lancaster Eprints |
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ftulancaster |
language |
unknown |
description |
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. |
format |
Article in Journal/Newspaper |
author |
Barker, Philip A. Hurrell, Elizabeth R. Leng, Melanie J. Wolff, Christian Cocquyt, Christine Sloane, Hilary J. Verschuren, Dirk |
spellingShingle |
Barker, Philip A. Hurrell, Elizabeth R. Leng, Melanie J. Wolff, Christian Cocquyt, Christine Sloane, Hilary J. Verschuren, Dirk Seasonality in equatorial climate over the past 25 k.y. revealed by oxygen isotope records from Mount Kilimanjaro |
author_facet |
Barker, Philip A. Hurrell, Elizabeth R. Leng, Melanie J. Wolff, Christian Cocquyt, Christine Sloane, Hilary J. Verschuren, Dirk |
author_sort |
Barker, Philip A. |
title |
Seasonality in equatorial climate over the past 25 k.y. revealed by oxygen isotope records from Mount Kilimanjaro |
title_short |
Seasonality in equatorial climate over the past 25 k.y. revealed by oxygen isotope records from Mount Kilimanjaro |
title_full |
Seasonality in equatorial climate over the past 25 k.y. revealed by oxygen isotope records from Mount Kilimanjaro |
title_fullStr |
Seasonality in equatorial climate over the past 25 k.y. revealed by oxygen isotope records from Mount Kilimanjaro |
title_full_unstemmed |
Seasonality in equatorial climate over the past 25 k.y. revealed by oxygen isotope records from Mount Kilimanjaro |
title_sort |
seasonality in equatorial climate over the past 25 k.y. revealed by oxygen isotope records from mount kilimanjaro |
publishDate |
2011 |
url |
https://eprints.lancs.ac.uk/id/eprint/53140/ https://doi.org/10.1130/G32419.1 |
geographic |
Austral |
geographic_facet |
Austral |
genre |
Ice cap ice core |
genre_facet |
Ice cap ice core |
op_relation |
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 1943-2682 |
op_doi |
https://doi.org/10.1130/G32419.1 |
container_title |
Geology |
container_volume |
39 |
container_issue |
12 |
container_start_page |
1111 |
op_container_end_page |
1114 |
_version_ |
1775351662510080000 |