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The Last Termination in the South Indian Ocean: A unique terrestrial record from Kerguelen Islands (49 degrees S) situated within the Southern Hemisphere westerly belt

Van der Putten, Nathalie LU ; Verbruggen, Cyriel; Björck, Svante LU ; Michel, Elisabeth; Disnar, Jean-Robert; Chapron, Emmanuel; Moine, Bertrand N. and de Beaulieu, Jacques-Louis (2015) In Quaternary Science Reviews 122. p.142-157
Abstract
The awareness of the significance of the Southern Ocean in the Earth's climate system has become increasingly obvious. The deglacial atmospheric CO2 rise during warming periods in Antarctica has been attributed to CO2 ventilation from the deep ocean caused by enhanced upwelling around the Antarctic Divergence. It has been hypothesized that, more intense Southern Hemisphere westerly winds aligned with the Antarctic Circumpolar Current due to a southward shift of the wind belt from its Last Glacial Maximum equator-ward position, are the main drivers. Reconstructions of past changes in atmospheric circulation in the Southern Hemisphere are still scarce and the overall picture is patchy with sometimes contradictory results. For obvious... (More)
The awareness of the significance of the Southern Ocean in the Earth's climate system has become increasingly obvious. The deglacial atmospheric CO2 rise during warming periods in Antarctica has been attributed to CO2 ventilation from the deep ocean caused by enhanced upwelling around the Antarctic Divergence. It has been hypothesized that, more intense Southern Hemisphere westerly winds aligned with the Antarctic Circumpolar Current due to a southward shift of the wind belt from its Last Glacial Maximum equator-ward position, are the main drivers. Reconstructions of past changes in atmospheric circulation in the Southern Hemisphere are still scarce and the overall picture is patchy with sometimes contradictory results. For obvious reasons, most terrestrial records originate from southern South America and New Zealand. Here we present a terrestrial record from the Indian sector of the Southern Ocean, from Kerguelen Islands located at 49 degrees S. A peat record is investigated using a multi-proxy approach (pollen and plant macrofossils, magnetic susceptibility, XRF analyses, biogenic silica content, Rock-Eval6 analysis and humification degree). Peat accumulation starts at about 16,000 cal yr BP with relatively warm and dry conditions. The most prominent change in our proxy data occurs at 13,600 cal yr BP, when peat ponds were established on the peat surface, resulting in lacustrine-type deposits, as a result of very high humidity, and with proxies implying very windy conditions. Within chronological uncertainties, this onset coincides with the onset of the so-called Oceanic Cold Reversal, based on the deuterium excess data in the EPICA Dome C ice core record. Kerguelen Islands are located in the moisture source area of Dome C and a change in atmospheric circulation at that time could explain both records. Around 12,900 cal yr BP, at the end of the Antarctic Cold Reversal, pond/lake sediments give way to more peaty deposits, with proxies suggesting slightly drier, less windy and probably warmer conditions. Kerguelen Islands became less influenced by the Southern Hemisphere westerly winds and these conditions were amplified during the early Holocene climate optimum as found in Antarctic ice core records. (C) 2015 Elsevier Ltd. All rights reserved. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Palaeoclimatology, Last Termination, Peat record, Kerguelen Islands, Southern Ocean, Indian Ocean, Oceanic Cold Reversal, Southern Hemisphere, westerly belt
in
Quaternary Science Reviews
volume
122
pages
142 - 157
publisher
Elsevier
external identifiers
  • wos:000358097300009
  • scopus:84934955812
ISSN
0277-3791
DOI
10.1016/j.quascirev.2015.05.010
language
English
LU publication?
yes
id
3dd81cd1-6440-4b21-bfc5-4a1d8e90b29e (old id 7773630)
date added to LUP
2015-09-18 15:47:38
date last changed
2017-04-09 03:18:38
@article{3dd81cd1-6440-4b21-bfc5-4a1d8e90b29e,
  abstract     = {The awareness of the significance of the Southern Ocean in the Earth's climate system has become increasingly obvious. The deglacial atmospheric CO2 rise during warming periods in Antarctica has been attributed to CO2 ventilation from the deep ocean caused by enhanced upwelling around the Antarctic Divergence. It has been hypothesized that, more intense Southern Hemisphere westerly winds aligned with the Antarctic Circumpolar Current due to a southward shift of the wind belt from its Last Glacial Maximum equator-ward position, are the main drivers. Reconstructions of past changes in atmospheric circulation in the Southern Hemisphere are still scarce and the overall picture is patchy with sometimes contradictory results. For obvious reasons, most terrestrial records originate from southern South America and New Zealand. Here we present a terrestrial record from the Indian sector of the Southern Ocean, from Kerguelen Islands located at 49 degrees S. A peat record is investigated using a multi-proxy approach (pollen and plant macrofossils, magnetic susceptibility, XRF analyses, biogenic silica content, Rock-Eval6 analysis and humification degree). Peat accumulation starts at about 16,000 cal yr BP with relatively warm and dry conditions. The most prominent change in our proxy data occurs at 13,600 cal yr BP, when peat ponds were established on the peat surface, resulting in lacustrine-type deposits, as a result of very high humidity, and with proxies implying very windy conditions. Within chronological uncertainties, this onset coincides with the onset of the so-called Oceanic Cold Reversal, based on the deuterium excess data in the EPICA Dome C ice core record. Kerguelen Islands are located in the moisture source area of Dome C and a change in atmospheric circulation at that time could explain both records. Around 12,900 cal yr BP, at the end of the Antarctic Cold Reversal, pond/lake sediments give way to more peaty deposits, with proxies suggesting slightly drier, less windy and probably warmer conditions. Kerguelen Islands became less influenced by the Southern Hemisphere westerly winds and these conditions were amplified during the early Holocene climate optimum as found in Antarctic ice core records. (C) 2015 Elsevier Ltd. All rights reserved.},
  author       = {Van der Putten, Nathalie and Verbruggen, Cyriel and Björck, Svante and Michel, Elisabeth and Disnar, Jean-Robert and Chapron, Emmanuel and Moine, Bertrand N. and de Beaulieu, Jacques-Louis},
  issn         = {0277-3791},
  keyword      = {Palaeoclimatology,Last Termination,Peat record,Kerguelen Islands,Southern Ocean,Indian Ocean,Oceanic Cold Reversal,Southern Hemisphere,westerly belt},
  language     = {eng},
  pages        = {142--157},
  publisher    = {Elsevier},
  series       = {Quaternary Science Reviews},
  title        = {The Last Termination in the South Indian Ocean: A unique terrestrial record from Kerguelen Islands (49 degrees S) situated within the Southern Hemisphere westerly belt},
  url          = {http://dx.doi.org/10.1016/j.quascirev.2015.05.010},
  volume       = {122},
  year         = {2015},
}