Investigating Subantarctic 14C Ages of different peat components: site and sample selection for developing robust age models in dynamic landscapes
Investigating Subantarctic 14C Ages of different peat components: site and sample selection for developing robust age models in dynamic landscapes
Precise radiocarbon (14C) dating of sedimentary sequences is important for developing robust chronologies of environmental change, but sampling of suitable components can be challenging in highly dynamic landscapes. Here we investigate radiocarbon determinations of different peat size fractions from six peat sites, representing a range of geomorphological contexts on the South Atlantic subantarctic islands of the Falklands and South Georgia. To investigate the most suitable fraction for dating, 112 measurements were obtained from three components within selected horizons: a fine fraction <0.2 mm, a coarse fraction >0.2 mm, and bulk material. We find site selection is critical, with locations surrounded by high-ground and/or relatively slowly accumulating sites more susceptible to the translocation of older carbon. Importantly, in locations with reduced potential for redeposition of material, our results show that there is no significant or systematic difference between ages derived from bulk material, fine or coarse (plant macrofossil) material, providing confidence in the resulting age model. Crucially, in areas comprising complex terrain with extreme relief, we recommend dating macrofossils or bulk carbon rather than a fine fraction, or employing comprehensive dating of multiple sedimentary fractions to determine the most reliable fraction(s) for developing a robust chronological framework.
age modeling, climate change, reworking, Southern Ocean, terrestrial
1009-1027
Thomas, Zoë A.
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Turney, Chris S.M.
5149b57c-77c2-4375-97a2-a4f00aa74d97
Hogg, Alan
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Williams, Alan N.
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Fogwill, Chris J.
3bad6ae9-5a6d-467e-b523-9d5ed0147455
1 August 2019
Thomas, Zoë A.
4b512d3a-3478-4270-9fdd-61256aa640d3
Turney, Chris S.M.
5149b57c-77c2-4375-97a2-a4f00aa74d97
Hogg, Alan
11978083-6632-42e2-ac46-4e0f9cd709c9
Williams, Alan N.
1cb0b99a-5e2d-4f60-8c0f-7f672c48736d
Fogwill, Chris J.
3bad6ae9-5a6d-467e-b523-9d5ed0147455
Thomas, Zoë A., Turney, Chris S.M., Hogg, Alan, Williams, Alan N. and Fogwill, Chris J.
(2019)
Investigating Subantarctic 14C Ages of different peat components: site and sample selection for developing robust age models in dynamic landscapes.
Radiocarbon, 61 (4), .
(doi:10.1017/RDC.2019.54).
Abstract
Precise radiocarbon (14C) dating of sedimentary sequences is important for developing robust chronologies of environmental change, but sampling of suitable components can be challenging in highly dynamic landscapes. Here we investigate radiocarbon determinations of different peat size fractions from six peat sites, representing a range of geomorphological contexts on the South Atlantic subantarctic islands of the Falklands and South Georgia. To investigate the most suitable fraction for dating, 112 measurements were obtained from three components within selected horizons: a fine fraction <0.2 mm, a coarse fraction >0.2 mm, and bulk material. We find site selection is critical, with locations surrounded by high-ground and/or relatively slowly accumulating sites more susceptible to the translocation of older carbon. Importantly, in locations with reduced potential for redeposition of material, our results show that there is no significant or systematic difference between ages derived from bulk material, fine or coarse (plant macrofossil) material, providing confidence in the resulting age model. Crucially, in areas comprising complex terrain with extreme relief, we recommend dating macrofossils or bulk carbon rather than a fine fraction, or employing comprehensive dating of multiple sedimentary fractions to determine the most reliable fraction(s) for developing a robust chronological framework.
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More information
e-pub ahead of print date: 10 June 2019
Published date: 1 August 2019
Additional Information:
Funding Information:
CSMT and CF acknowledge the support of the Australian Research Council (FL100100195, FT120100004 and DP130104156). We thank the captain and crew of the Fishery Patrol Vessel The Pharos for travel to and from South Georgia, and the Government of South Georgia and the South Sandwich Islands, and the Falkland Islands Government for permission to undertake sampling on the island (permit numbers SGEP0110/11 and R07/2011, respectively). Darren Christie kindly assisted with the fieldwork on the Falkland Islands, and Charlotte Cook helped prepare the samples in the laboratory. We would like to thank two anonymous reviewers and Associate Editor Pieter Grootes for their thorough reviews and helpful comments, which helped to improve the manuscript.
Publisher Copyright:
© 2019 by the Arizona Board of Regents on behalf of the University of Arizona.
Keywords:
age modeling, climate change, reworking, Southern Ocean, terrestrial
Identifiers
Local EPrints ID: 476221
URI: http://eprints.soton.ac.uk/id/eprint/476221
ISSN: 0033-8222
PURE UUID: 8a04ead8-9d77-4eb3-891a-489488eb403e
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Date deposited: 14 Apr 2023 16:47
Last modified: 18 Mar 2024 04:10
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Contributors
Author:
Zoë A. Thomas
Author:
Chris S.M. Turney
Author:
Alan Hogg
Author:
Alan N. Williams
Author:
Chris J. Fogwill
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