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Holocene glacier fluctuations and environmental changes in subantarctic South Georgia inferred from a sediment record from a coastal inlet

Published online by Cambridge University Press:  30 October 2018

Sonja Berg ,
Duanne A. White ,
Sandra Jivcov ,
Martin Melles ,
Melanie J. Leng ,
Janet Rethemeyer ,
Claire Allen ,
Bianca Perren ,
Ole Bennike  and
Finn Viehberg
Sonja Berg*
Affiliation:
Institute of Geology and Mineralogy, University of Cologne, 50674 Cologne, Germany
Duanne A. White
Affiliation:
Institute for Applied Ecology, University of Canberra, Canberra, Australian Capital Territory 2601, Australia
Sandra Jivcov
Affiliation:
Institute of Geology and Mineralogy, University of Cologne, 50674 Cologne, Germany
Martin Melles
Affiliation:
Institute of Geology and Mineralogy, University of Cologne, 50674 Cologne, Germany
Melanie J. Leng
Affiliation:
NERC Isotopes Geosciences Facilities, British Geological Survey, Keyworth, Nottingham NG12 5GG, United Kingdom School of Biosciences, Centre for Environmental Geochemistry, The University of Nottingham, Sutton Bonington Campus, Leicestershire LE12 5RD, United Kingdom
Janet Rethemeyer
Affiliation:
Institute of Geology and Mineralogy, University of Cologne, 50674 Cologne, Germany
Claire Allen
Affiliation:
British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 0ET, United Kingdom
Bianca Perren
Affiliation:
British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 0ET, United Kingdom
Ole Bennike
Affiliation:
Geological Survey of Denmark and Greenland, Øster Voldgade 10, 1350Copenhagen, Denmark
Finn Viehberg
Affiliation:
Institute of Geology and Mineralogy, University of Cologne, 50674 Cologne, Germany
*
*Corresponding author at: Institute of Geology and Mineralogy, University of Cologne, Zuelpicher Strasse 49a, 50674 Cologne, Germany. E-mail address: [email protected] (S. Berg).
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Abstract

The subantarctic island of South Georgia provides terrestrial and coastal marine records of climate variability, which are crucial for the understanding of the drivers of Holocene climate changes in the subantarctic region. Here we investigate a sediment core (Co1305) from a coastal inlet on South Georgia using elemental, lipid biomarker, diatom, and stable isotope data to infer changes in environmental conditions and to constrain the timing of late-glacial and Holocene glacier fluctuations. Because of the scarcity of terrestrial macrofossils and the presence of redeposited and relict organic matter in the sediments, age control for the record was obtained by compound-specific radiocarbon dating of mostly marine-derived n-C16 fatty acids. A basal till layer recovered in Little Jason Lagoon was likely deposited during an advance of local glaciers during the Antarctic cold reversal. After glacier retreat, an oligotrophic lake occupied the site, which transitioned to a marine inlet around 8.0±0.9 ka because of relative sea-level rise. From 7.0±0.6 to 4.0±0.4 ka, reduced vegetation coverage in the catchment, as well as high siliciclastic input and deposition of ice-rafted debris, indicates glacier advances in the terrestrial catchment and likely in the adjacent fjord. A second, less extensive period of glacier advances occurred in the late Holocene, after 1.8±0.3 ka.

Keywords

South GeorgiaHoloceneGlacier advanceCompound-specific radiocarbon analysisMarine sedimentsRelative sea level
Type
Research Article
Information
Quaternary Research , Volume 91 , Issue 1 , January 2019 , pp. 132 - 148
Copyright
Copyright © University of Washington. Published by Cambridge University Press, 2018. 

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