Were the Larsemann Hills ice-free through the Last Glacial Maximum?
Lake sediments in the Larsemann Hills contain a great diversity of biological and physical markers from which past environments can be inferred. In order to determine the timing of environmental changes it is essential to have accurate dating of sediments. We used radiometric (Pb-210 and Cs-137), ra...
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Cambridge Univ Press
2001
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Online Access: | http://hdl.handle.net/2078.1/42387 |
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ftunistlouisbrus:oai:dial.uclouvain.be:boreal:42387 2024-05-12T07:56:17+00:00 Were the Larsemann Hills ice-free through the Last Glacial Maximum? Hodgson, DA Noon, PE Vyverman, W Bryant, CL Gore, DB Appleby, P Gilmour, M Verleyen, E Sabbe, K Jones, VJ Ellis-Evans, JC Wood, PB UCL 2001 http://hdl.handle.net/2078.1/42387 eng eng Cambridge Univ Press boreal:42387 http://hdl.handle.net/2078.1/42387 urn:ISSN:0954-1020 urn:EISSN:1365-2079 Antarctic Science, Vol. 13, no. 4, p. 440-454 (2001) Antarctic deglaciation Holocene lakes Larsemann Hills Pleistocene info:eu-repo/semantics/article 2001 ftunistlouisbrus 2024-04-18T18:14:34Z Lake sediments in the Larsemann Hills contain a great diversity of biological and physical markers from which past environments can be inferred. In order to determine the timing of environmental changes it is essential to have accurate dating of sediments. We used radiometric (Pb-210 and Cs-137), radiocarbon (AMS C-14) and uranium series (U-238) methods to date cores from eleven lakes. These were sampled on coastal to inland transects across the two main peninsulas, Broknes and Stornes, together with a single sample from the Bolingen Islands. Radiometric dating of recent sediments yielded Pb-210 levels below acceptable detection limits. However, a relatively well-defined peak in Cs-137 gave a date marker which corresponds to the fallout maximum from the atmospheric testing of atomic weapons in 1964/65. Radiocarbon (AMS 14C) measurements showed stratigraphical consistency in the age-depth sequences and undisturbed laminae in some cores provides evidence that the sediments have remained undisturbed by glacial action. In addition, freshwater surface sediments were found to be in near-equilibrium with modem C-14, and not influenced by radiocarbon contamination processes. This dating program, together with geomorphological records of ice flow directions and glacial sediments, indicates that parts of Broknes were ice-free throughout the Last Glacial Maximum and that some lakes have existed continuously since at least 44 ka BP. Attempts to date sediments older than 44 ka BP using U-238 dating were inconclusive. However, supporting evidence for Broknes being ice-free is provided by an Optically Stimulated Luminescence date from a glaciofluvial deposit. In contrast, Stornes only became ice-free in the mid to late Holocene. This contrasting glacial history results from the Dalk Glacier which diverts ice around Broknes. Lakes on Broknes and some offshore islands therefore contain the oldest known lacustrine sediment records from eastern Antarctica, with the area providing an ice-free oasis and refuge for plants and animals ... Article in Journal/Newspaper Antarc* Antarctic Antarctic Science Antarctica DIAL@USL-B (Université Saint-Louis, Bruxelles) Antarctic Larsemann Hills ENVELOPE(76.217,76.217,-69.400,-69.400) Broknes ENVELOPE(76.346,76.346,-69.391,-69.391) Stornes ENVELOPE(76.099,76.099,-69.429,-69.429) Bolingen Islands ENVELOPE(75.696,75.696,-69.532,-69.532) |
institution |
Open Polar |
collection |
DIAL@USL-B (Université Saint-Louis, Bruxelles) |
op_collection_id |
ftunistlouisbrus |
language |
English |
topic |
Antarctic deglaciation Holocene lakes Larsemann Hills Pleistocene |
spellingShingle |
Antarctic deglaciation Holocene lakes Larsemann Hills Pleistocene Hodgson, DA Noon, PE Vyverman, W Bryant, CL Gore, DB Appleby, P Gilmour, M Verleyen, E Sabbe, K Jones, VJ Ellis-Evans, JC Wood, PB Were the Larsemann Hills ice-free through the Last Glacial Maximum? |
topic_facet |
Antarctic deglaciation Holocene lakes Larsemann Hills Pleistocene |
description |
Lake sediments in the Larsemann Hills contain a great diversity of biological and physical markers from which past environments can be inferred. In order to determine the timing of environmental changes it is essential to have accurate dating of sediments. We used radiometric (Pb-210 and Cs-137), radiocarbon (AMS C-14) and uranium series (U-238) methods to date cores from eleven lakes. These were sampled on coastal to inland transects across the two main peninsulas, Broknes and Stornes, together with a single sample from the Bolingen Islands. Radiometric dating of recent sediments yielded Pb-210 levels below acceptable detection limits. However, a relatively well-defined peak in Cs-137 gave a date marker which corresponds to the fallout maximum from the atmospheric testing of atomic weapons in 1964/65. Radiocarbon (AMS 14C) measurements showed stratigraphical consistency in the age-depth sequences and undisturbed laminae in some cores provides evidence that the sediments have remained undisturbed by glacial action. In addition, freshwater surface sediments were found to be in near-equilibrium with modem C-14, and not influenced by radiocarbon contamination processes. This dating program, together with geomorphological records of ice flow directions and glacial sediments, indicates that parts of Broknes were ice-free throughout the Last Glacial Maximum and that some lakes have existed continuously since at least 44 ka BP. Attempts to date sediments older than 44 ka BP using U-238 dating were inconclusive. However, supporting evidence for Broknes being ice-free is provided by an Optically Stimulated Luminescence date from a glaciofluvial deposit. In contrast, Stornes only became ice-free in the mid to late Holocene. This contrasting glacial history results from the Dalk Glacier which diverts ice around Broknes. Lakes on Broknes and some offshore islands therefore contain the oldest known lacustrine sediment records from eastern Antarctica, with the area providing an ice-free oasis and refuge for plants and animals ... |
author2 |
UCL |
format |
Article in Journal/Newspaper |
author |
Hodgson, DA Noon, PE Vyverman, W Bryant, CL Gore, DB Appleby, P Gilmour, M Verleyen, E Sabbe, K Jones, VJ Ellis-Evans, JC Wood, PB |
author_facet |
Hodgson, DA Noon, PE Vyverman, W Bryant, CL Gore, DB Appleby, P Gilmour, M Verleyen, E Sabbe, K Jones, VJ Ellis-Evans, JC Wood, PB |
author_sort |
Hodgson, DA |
title |
Were the Larsemann Hills ice-free through the Last Glacial Maximum? |
title_short |
Were the Larsemann Hills ice-free through the Last Glacial Maximum? |
title_full |
Were the Larsemann Hills ice-free through the Last Glacial Maximum? |
title_fullStr |
Were the Larsemann Hills ice-free through the Last Glacial Maximum? |
title_full_unstemmed |
Were the Larsemann Hills ice-free through the Last Glacial Maximum? |
title_sort |
were the larsemann hills ice-free through the last glacial maximum? |
publisher |
Cambridge Univ Press |
publishDate |
2001 |
url |
http://hdl.handle.net/2078.1/42387 |
long_lat |
ENVELOPE(76.217,76.217,-69.400,-69.400) ENVELOPE(76.346,76.346,-69.391,-69.391) ENVELOPE(76.099,76.099,-69.429,-69.429) ENVELOPE(75.696,75.696,-69.532,-69.532) |
geographic |
Antarctic Larsemann Hills Broknes Stornes Bolingen Islands |
geographic_facet |
Antarctic Larsemann Hills Broknes Stornes Bolingen Islands |
genre |
Antarc* Antarctic Antarctic Science Antarctica |
genre_facet |
Antarc* Antarctic Antarctic Science Antarctica |
op_source |
Antarctic Science, Vol. 13, no. 4, p. 440-454 (2001) |
op_relation |
boreal:42387 http://hdl.handle.net/2078.1/42387 urn:ISSN:0954-1020 urn:EISSN:1365-2079 |
_version_ |
1798836279150903296 |