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

Type Article
Date 2015-08
Language English
Author(s) Van Der Putten Nathalie1, Verbruggen Cyriel2, Bjorck Svante1, Michel Elisabeth3, Disnar Jean-Robert4, Chapron Emmanuel4, Moine Bertrand N.5, de Beaulieu Jacques-Louis6
Affiliation(s) 1 : Lund Univ, Dept Geol, Quaternary Sci, S-22364 Lund, Sweden.
2 : Univ Ghent, Dept Geol & Soil Sci, B-9000 Ghent, Belgium.
3 : LSCE, Lab Mixte CNRS CEA UVSQ, F-91198 Gif Sur Yvette, France.
4 : Univ Orleans, CNRS, BRGM, Inst Sci Terre Orleans,ISTO,UMR 7327, F-45071 Orleans 2, France.
5 : Univ St Etienne, Univ Lyon, Lab Magmas & Volcans UMR CNRS 6524, F-42023 St Etienne, France.
6 : Aix Marseille Univ, IMBE UMR CNRS IRD 7263, F-13545 Aix En Provence 04, France.
Source Quaternary Science Reviews (0277-3791) (Pergamon-elsevier Science Ltd), 2015-08 , Vol. 122 , P. 142-157
DOI 10.1016/j.quascirev.2015.05.010
WOS© Times Cited 16
Keyword(s) Palaeoclimatology, Last Termination, Peat record, Kerguelen Islands, Southern Ocean, Indian Ocean, Oceanic Cold Reversal, Southern Hemisphere westerly belt
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.

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Appendix A. Supplementary data - SEM images at 413, 430, 440 cm depth showing that the samples are dominated by diatom frustules and fine grained minerogenic material. 172 KB Open access
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How to cite 

Van Der Putten Nathalie, Verbruggen Cyriel, Bjorck Svante, Michel Elisabeth, Disnar Jean-Robert, Chapron Emmanuel, Moine Bertrand N., de Beaulieu Jacques-Louis (2015). The Last Termination in the South Indian Ocean: A unique terrestrial record from Kerguelen Islands (49 ° S) situated within the Southern Hemisphere westerly belt. Quaternary Science Reviews, 122, 142-157. Publisher's official version : https://doi.org/10.1016/j.quascirev.2015.05.010 , Open Access version : https://archimer.ifremer.fr/doc/00497/60843/