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Pleistocene glacial history of the New Zealand subantarctic islands

Pleistocene glacial history of the New Zealand subantarctic islands
Pleistocene glacial history of the New Zealand subantarctic islands
The New Zealand subantarctic islands of Auckland and Campbell, situated between the subtropical front and the Antarctic Convergence in the Pacific sector of the Southern Ocean, provide valuable terrestrial records from a globally important climatic region. Whilst the islands show clear evidence of past glaciation, the timing and mechanisms behind Pleistocene environmental and climate changes remain uncertain. Here we present a multidisciplinary study of the islands-including marine and terrestrial geomorphological surveys, extensive analyses of sedimentary sequences, a comprehensive dating programme, and glacier flow line modelling-to investigate multiple phases of glaciation across the islands. We find evidence that the Auckland Islands hosted a small ice cap 384 000±26 000 years ago (384±26 ka), most likely during Marine Isotope Stage 10, a period when the subtropical front was reportedly north of its present-day latitude by several degrees, and consistent with hemispheric-wide glacial expansion. Flow line modelling constrained by field evidence suggests a more restricted glacial period prior to the LGM that formed substantial valley glaciers on the Campbell and Auckland Islands around 72-62 ka. Despite previous interpretations that suggest the maximum glacial extent occurred in the form of valley glaciation at the Last Glacial Maximum (LGM; ∼ 21 ka), our combined approach suggests minimal LGM glaciation across the New Zealand subantarctic islands and that no glaciers were present during the Antarctic Cold Reversal (ACR; ∼ 15-13 ka). Instead, modelling implies that despite a regional mean annual air temperature depression of ∼ 5 °C during the LGM, a combination of high seasonality and low precipitation left the islands incapable of sustaining significant glaciation. We suggest that northwards expansion of winter sea ice during the LGM and subsequent ACR led to precipitation starvation across the middle to high latitudes of the Southern Ocean, resulting in restricted glaciation of the subantarctic islands.
1814-9324
423-448
Rainsley, Eleanor
4fe1e6f6-b8c2-46b3-8e94-1149b980a55a
Turney, Chris S.M.
5149b57c-77c2-4375-97a2-a4f00aa74d97
Golledge, Nicholas R.
6e5f88b4-366b-49f9-81fe-3354a1bd7d88
Wilmshurst, Janet M.
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McGlone, Matt S.
b84ad1a5-3a14-4f14-a70f-9ee3e386cb48
Hogg, Alan G.
11978083-6632-42e2-ac46-4e0f9cd709c9
Li, Bo
ff6006d5-9415-4ddd-b641-005ab8fc18d9
Thomas, Zoë A.
4b512d3a-3478-4270-9fdd-61256aa640d3
Roberts, Richard
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Jones, Richard T.
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Palmer, Jonathan G.
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Flett, Verity
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De Wet, Gregory
850275c7-2c9b-47bb-b3f1-d02f4e804510
Hutchinson, David K.
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Lipson, Mathew J.
f599592a-28ae-4ede-9c7b-e484e3f94c62
Fenwick, Pavla
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Hines, Ben
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Binetti, Umberto
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Fogwill, Christopher J.
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et al.
Rainsley, Eleanor
4fe1e6f6-b8c2-46b3-8e94-1149b980a55a
Turney, Chris S.M.
5149b57c-77c2-4375-97a2-a4f00aa74d97
Golledge, Nicholas R.
6e5f88b4-366b-49f9-81fe-3354a1bd7d88
Wilmshurst, Janet M.
3738ab11-0f7b-4550-b8d3-f63198b3394e
McGlone, Matt S.
b84ad1a5-3a14-4f14-a70f-9ee3e386cb48
Hogg, Alan G.
11978083-6632-42e2-ac46-4e0f9cd709c9
Li, Bo
ff6006d5-9415-4ddd-b641-005ab8fc18d9
Thomas, Zoë A.
4b512d3a-3478-4270-9fdd-61256aa640d3
Roberts, Richard
16aadf2d-cd4f-4cc9-97f5-cda729139d89
Jones, Richard T.
f8b5db51-10c7-4b4e-81e3-e5c3833eb2ce
Palmer, Jonathan G.
6b327a39-f234-4cdc-ae73-0c48340f05b3
Flett, Verity
6670c523-b114-4296-9513-fe05d1cdce60
De Wet, Gregory
850275c7-2c9b-47bb-b3f1-d02f4e804510
Hutchinson, David K.
9db108b8-88f0-4c3a-a61b-0af71ab97501
Lipson, Mathew J.
f599592a-28ae-4ede-9c7b-e484e3f94c62
Fenwick, Pavla
8ce718a6-f147-4eac-9878-f8b67c491a70
Hines, Ben
5deb353f-872a-4cfc-9205-417694820df7
Binetti, Umberto
b079bcd2-6718-47a5-b65b-2b2c4081e86a
Fogwill, Christopher J.
3bad6ae9-5a6d-467e-b523-9d5ed0147455

Rainsley, Eleanor, Turney, Chris S.M., Golledge, Nicholas R. and Thomas, Zoë A. , et al. (2019) Pleistocene glacial history of the New Zealand subantarctic islands. Climate of the Past, 15 (2), 423-448. (doi:10.5194/cp-15-423-2019).

Record type: Article

Abstract

The New Zealand subantarctic islands of Auckland and Campbell, situated between the subtropical front and the Antarctic Convergence in the Pacific sector of the Southern Ocean, provide valuable terrestrial records from a globally important climatic region. Whilst the islands show clear evidence of past glaciation, the timing and mechanisms behind Pleistocene environmental and climate changes remain uncertain. Here we present a multidisciplinary study of the islands-including marine and terrestrial geomorphological surveys, extensive analyses of sedimentary sequences, a comprehensive dating programme, and glacier flow line modelling-to investigate multiple phases of glaciation across the islands. We find evidence that the Auckland Islands hosted a small ice cap 384 000±26 000 years ago (384±26 ka), most likely during Marine Isotope Stage 10, a period when the subtropical front was reportedly north of its present-day latitude by several degrees, and consistent with hemispheric-wide glacial expansion. Flow line modelling constrained by field evidence suggests a more restricted glacial period prior to the LGM that formed substantial valley glaciers on the Campbell and Auckland Islands around 72-62 ka. Despite previous interpretations that suggest the maximum glacial extent occurred in the form of valley glaciation at the Last Glacial Maximum (LGM; ∼ 21 ka), our combined approach suggests minimal LGM glaciation across the New Zealand subantarctic islands and that no glaciers were present during the Antarctic Cold Reversal (ACR; ∼ 15-13 ka). Instead, modelling implies that despite a regional mean annual air temperature depression of ∼ 5 °C during the LGM, a combination of high seasonality and low precipitation left the islands incapable of sustaining significant glaciation. We suggest that northwards expansion of winter sea ice during the LGM and subsequent ACR led to precipitation starvation across the middle to high latitudes of the Southern Ocean, resulting in restricted glaciation of the subantarctic islands.

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More information

Accepted/In Press date: 17 December 2018
Published date: 14 March 2019
Additional Information: Funding Information: Acknowledgements. First and foremost, we must acknowledge the contribution of Richard Jones, who was integral to this work and is dearly missed. The work was supported by the Australasian Antarctic Expedition 2013–2014, the Australian Research Council (FL100100195, FT120100004, DE130101336, and DP130104156), and the University of New South Wales. Matt S. McGlone and Janet M. Wilmshurst were supported by Core Funding for Crown Research Institutes from the New Zealand Ministry of Business, Innovation and Employment’s Science and Innovation Group. Major thanks to the captain and crew of the MV Akademik Shokalskiy, James MacDiarmid and Ben Fink, and Henk Haazen and Kali Kahn on the Tiama for all their help in the field. Research on the New Zealand subantarctic Auckland and Campbell Islands was undertaken under the New Zealand Department of Conservation national authorisation numbers 37687-FAU and 39761-RES. Thanks to Jenny Dahl of the Rafter Radiocarbon Laboratory for advising on radiocarbon age NZA4509. Particle analysis was undertaken at the University of Exeter. We thank two anonymous reviewers for their helpful comments. Publisher Copyright: © 2019 Author(s).

Identifiers

Local EPrints ID: 476099
URI: http://eprints.soton.ac.uk/id/eprint/476099
ISSN: 1814-9324
PURE UUID: f8ed6322-7cbe-4b36-bb84-46095b97928f
ORCID for Zoë A. Thomas: ORCID iD orcid.org/0000-0002-2323-4366

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Date deposited: 12 Apr 2023 14:07
Last modified: 18 Mar 2024 04:10

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Contributors

Author: Eleanor Rainsley
Author: Chris S.M. Turney
Author: Nicholas R. Golledge
Author: Janet M. Wilmshurst
Author: Matt S. McGlone
Author: Alan G. Hogg
Author: Bo Li
Author: Zoë A. Thomas ORCID iD
Author: Richard Roberts
Author: Richard T. Jones
Author: Jonathan G. Palmer
Author: Verity Flett
Author: Gregory De Wet
Author: David K. Hutchinson
Author: Mathew J. Lipson
Author: Pavla Fenwick
Author: Ben Hines
Author: Umberto Binetti
Author: Christopher J. Fogwill
Corporate Author: et al.

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